ArticlePDF Available

Forest Bathing Enhances Human Natural Killer Activity and Expression of Anti-Cancer Proteins

Authors:
  • RIKEN, Center for integrative Medical Science

Abstract

In order to explore the effect of forest bathing on human immune function, we investigated natural killer (NK) activity; the number of NK cells, and perforin, granzymes and granulysin-expression in peripheral blood lymphocytes (PBL) during a visit to forest fields. Twelve healthy male subjects, age 37-55 years, were selected with informed consent from three large companies in Tokyo, Japan. The subjects experienced a three-day/two-night trip in three different forest fields. On the first day, subjects walked for two hours in the afternoon in a forest field; and on the second day, they walked for two hours in the morning and afternoon, respectively, in two different forest fields. Blood was sampled on the second and third days, and NK activity; proportions of NK, T cells, granulysin, perforin, and granzymes A/B-expressing cells in PBL were measured. Similar measurements were made before the trip on a normal working day as the control. Almost all of the subjects (11/12) showed higher NK activity after the trip (about 50 percent increased) compared with before. There are significant differences both before and after the trip and between days 1 and 2 in NK activity. The forest bathing trip also significantly increased the numbers of NK, perforin, granulysin, and granzymes A/B-expressing cells. Taken together, these findings indicate that a forest bathing trip can increase NK activity, and that this effect at least partially mediated by increasing the number of NK cells and by the induction of intracellular anti-cancer proteins.
A forest bathing trip increases human natural killer activity and expression of anti-cancer
proteins: a comparison with a trip to a place without forest
Qing Li1*, Kanehisa Morimoto2, Maiko Kobayashi1, Hirofumi Inagaki1, Masao Katsumata1,
Yukiyo Hirata1, Kimiko Hirata1, Hiroko Suzuki1, Yingji Li1, Yoko Wakayama1, Tomoyuki
Kawada1, Yoshifumi Miyazaki3, Takahide Kagawa3, Tatsuro Ohira3, Norimasa Takayama3,
Alan M. Krensky4
1 Department of Hygiene and Public Health, Nippon Medical School, Tokyo, Japan
2 Department of Social and Environmental Medicine, Osaka University Graduate School of
Medicine, Osaka, Japan
3 Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan
4 Stanford University School of Medicine, Palo Alto, CA, USA
*Corresponding author
Qing Li, MD, Ph.D
Department of Hygiene and Public Health, Nippon Medical School,
1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan
e-mail: qing-li@nms.ac.jp
Tel: +81-3-3822-2131
Fax: +81-3-5685-3065
1
Abstract
We previously have reported that a forest bathing trip (Shinlinyoku) enhanced human natural
killer (NK) activity; number of NK cells, and perforin, granzymes and granulysin-expression
in peripheral blood lymphocytes (PBL). In the present study, we investigated how long the
increased NK activity will be lasted and also compared the effect of a forest bathing trip on
NK activity with a trip to a place without forest (general trip). 12 healthy male subjects, age
35-56 years, were selected with informed consent from four large companies in Tokyo, Japan.
The subjects experienced a three-day/two-night trip at forest fields and a place without forest.
On the first day, subjects walked for two hours in the afternoon in a forest field; and on the
second day, they walked for two hours in the morning and afternoon, respectively, at two
different forest fields. Blood was sampled on the second and third days during the trip, and on
days 7 and 30 after the trip, and NK activity; numbers of NK, T cells, granulysin, perforin,
and granzymes A/B-expressing cells in PBL were measured. Similar measurements were
made before the trip on a normal working day as the control. The forest bathing trip
significantly increased NK activity, the numbers of NK, perforin, granulysin, and granzymes
A/B-expressing cells. The increased NK activity was lasted for more than 7 days after the trip.
On the other hand, a general trip did not increase NK activity, the numbers of NK, and
intracellular anti-cancer proteins. Taken together, these findings indicate that a forest bathing
trip can increase NK activity, the number of NK cells and intracellular anti-cancer proteins,
and that this effect at least lasts more than 7 days after the trip.
Key words: anti-cancer proteins, forest bathing, NK activity, granulysin, granzyme, perforin
2
Introduction
A forest bathing trip, called “Shinrinyoku” in Japanese, involves a visit to a forest field for
the purpose of relaxation and recreation by breathing in the volatile substances, called
phytocide released from tree, (Li et al., 2007). It was first proposed in the 1980s and has
become a recognized relaxation activity in Japan (Ohtsuka et al., 1998; Yamaguchi et al.
2006; Morita et al., 2007; Li et al., 2007). Since forests occupy 67% of the land in Japan
(Forestry Agency of Japan, 2002), participation in forest bathing trip is easily accessible.
According to a public opinion poll conducted in Japan in 2003, 25.6% of respondents had
participated in forest bathing trip, indicating the popularity of forest bathing trip in Japan
(Morita et al., 2007). Moreover, forest bathing trip is possible in forest environments in the
world. We previously have reported that phytoncytes enhanced human natural killer (NK)
activity and intracellular levels of perforin, granulysin and granzyme A in NK cells in vitro (Li
et al. 2006a). Komori et al. (1995) also reported that citrus fragrance found in the forest
affects the human endocrine and immune systems as analyzed by measurement of urinary
cortisol and dopamine levels, NK activity and CD4/8 ratios. These findings strongly suggest
that forest bathing trip may have beneficial effects on human immune function, thus, we
previously have investigated the effect of forest bathing trip on human NK activity, and found
that a forest bathing trip increased human NK activity, number of NK cell, and intracellular
levels of perforin, granulysin and granzymes A/B in peripheral blood lymphocytes (PBL) (Li
et al., 2007). However, there are two questions remained to be resolved: one is that whether a
trip to a place without forest (a general trip) also can increase NK activity? Another is that
3
how long the increased NK activity will be lasted after a forest bathing trip? In the present
study, we conducted two investigations to resolve the above-mentioned two questions.
Subjects and methods
Subjects
Twelve healthy male subjects, aged 35-56 years (45.1±6.7), were selected from four large
companies in Tokyo, Japan in the present study. The information gathered from a self-
administered questionnaire including age, and lifestyle habits that asked about cigarette
smoking, alcohol drinking habits, eating breakfast, sleeping hours, working hours, physical
exercise, nutritional balance and mental stress, which have been reported previously (Li et al.,
2006b; 2007). Written informed consent was obtained from all subjects after a full
explanation of the study procedures. None of the subjects had any signs or symptoms of
infectious disease, used drugs that might affect immunological analysis, or were taking any
medications at the time of the study. The ethics committee of the Nippon Medical School
approved this study (approval No. 16-1).
Forest bathing trip and a trip to a place without forest (general trip)
In the forest bathing trip, the subjects experienced a three-day/two-night trip at three different
forest fields in early September, 2006. On the first day, subjects walked for two hours in the
afternoon in a forest field, and then stayed at a nearby hotel within the forest. On the second
day, subjects walked for 2 hours in the morning and afternoon, respectively, at two different
forest fields. Whereas, in the general trip, the subjects experienced a three-day/two-night trip
4
at a city in middle May, 2006. On the first day, subjects walked for two hours in the afternoon
in a tourist rout in a city, and then stayed at a hotel in the city. On the second day, subjects
walked for 2 hours in the morning and afternoon, respectively, at two different tourist routs in
the same city. Each course in the both trips was 2.5 km, closely resembling normal physical
activity for the subjects on normal working days. Daily physical activity of the subjects was
monitored with a pedometer and the duration of sleep was measured with a piezo-electric
accelerometer, Actiwatch(R) (Mini Mitter Co. Inc., Sunriver), worn on the wrist of the non-
dominant arm. The validation study was previously reported (Kawada et al. 2001). Blood was
sampled on the second and third days during the trips, and days 7 and 30 after the forest
bathing trip and three days prior to the trips as a control. Since it has been reported that
human NK cell activity shows circadian rhythms (Angeli 1992), all samples were obtained at
8:00 am. All blood samples were placed in an ice/water box at 4°C and assays performed
within four hours of the blood draw. NK activity; proportions of NK, T cells, granulysin,
perforin, and granzymes A/B-expressing cells in peripheral blood lymphocytes (PBL), counts
of white blood cells were measured. Adrenaline concentration in urine also was determined.
Reagents
RPMI 1640 was purchased from Nissui Pharmaceutical (Tokyo, Japan). Fetal bovine
serum (FBS) was purchased from JRH Biosciences (Lenexa, KS), and heat-inactivated at
56°C for 30 min prior to use. Sodium 51Cr-chromate was obtained from PerkinElmer (Boston,
MA). Fluorescein isothiocynate (FITC)-mouse anti-human perforin, granzyme A (GrA),
granzyme B (GrB) and FITC/phycoerythrin (PE)-CD16, PerCP-Cy5.5-CD3, FITC/PE-
5
negative isotypic control antibodies, and Cytofix/cytoperm solution were purchased from BD
Pharmingen (San Diego, CA). Rabbit anti-human granulysin (GRN) polyclonal antibody was
described previously (Hanson et al. 1999). PE-goat-anti rabbit IgG were purchased from
Vector Laboratories Inc. (Burlingame, CA).
NK activity
Human peripheral blood lymphocytes (PBL) were separated from peripheral blood with
BD Vacutainer CPT (Becton Dickinson, Franklin Lakes, NJ), and then adjusted to 4x106
cells/ml for the assay of NK activity. The viability of the cells as determined by trypan blue
dye exclusion was more than 95%. Human NK activity was assayed according to the
traditional method (Li et al., 2007). Briefly, K-562 target cells were labeled with a sodium
51Cr-chromate solution for 60 min at 37°C in 5% CO2 and washed 4 times in RPMI 1640
containing 10% FBS. The target cells were plated into round-bottomed 96-well microplates,
then the effector cells (PBL) at 4x106, 2x106 and 1x106 cells/ml in 100 µl were added to the
wells in triplicate at E:T ratios of 40:1, 20:1 and 10:1. Following a 4-hr incubation at 37°C in
5% CO2, the microplates were centrifuged and 100 µl of supernatant from each well was
collected and measured in a gamma counter. Then, the NK activity was calculated as
described previously (Li et al., 2007).
Cell staining and flow cytometric analysis
The surface markers of PBL were stained with PE/FITC-CD16 for NK cells and PerCP-
Cy5.5-CD3 for T cells for 30 min in the dark. Then, the cells were fixed/permeablized with
Cytofix/cytoperm solution for 20 min at 4°C, and then the intracellular perforin and GrA/B
6
were stained with FITC- anti-human perforin and GrA/B, respectively, for 30 min at 4°C
according to the manufacturer’s instructions (BD PharMingen, San Diego, CA). Intracellular
GRN was stained with rabbit anti-human GRN polyclonal Ab after fixation/permeablization
with Cytofix/cytoperm solution, and then stained with PE-goat anti-rabbit IgG for 30 minutes
at 4°C in the dark. After staining, the cells were washed twice with the fixative solution and
once with PBS containing 1% FBS. Flow cytometric analysis was performed with a FACScan
flow cytometer (Becton Dickinson, San Jose, CA) as described previously (Li et al. 2005;
2006b; 2007). Lymphocytes were identified by their characteristic appearance on a dot plot of
FSC versus SSC and electronically gated to exclude dead cells and granulocytes.
Measurements for adrenaline in urine
The levels of adrenalin in urine were measured by HPLC method using an analyzer HLC-
725CAII. The instrument features a column-switching system composed of two pretreatment
columns and one separation column and a high-sensitive detection unit based on a post-
column reaction using a fluorogenic reagent, 1,2-diphenylethyleneamine. The detection limit
of adrenaline in urine was 8 fmol/ml (Hirowatari et al., 1999).
White blood cell (WBC) count
WBC, RBC and platelet counts, the percentages of granulocyte, lymphocyte and
macrophage, concentration of Hb, Hct, MCV, MCH and MHCH were determined by an
automatic cell counter (LC-550, Horiba Co., LTD. Kyoto, Japan) as described previously (Li
et al. 2007).
Measurements of phytoncide, and environmental temperature/ humidity in the forest fields
7
during the investigation
The volatile organic compounds (phytoncide) in forest air, and temperature and humidity in the
forest fields were measured as previously reported (Li et al., 2007).
Statistical analysis
Multiple comparisons were made with the paired t-test if the analysis of variance was
significant. The analysis was performed with the SPSS 11.5J software package for Windows.
The significance level for p values was set at < 0.05.
Results
Effect of a forest bathing trip and the general trip on NK activity
Because the difference among individuals in NK activity is very big, we do not compare the
difference in NK activity between the forest bathing trip and general trip, but compared the
difference in NK activity between before and after the trips in the present study.
As shown in Fig. 1A, forest bathing trip significantly increased human NK activity, and this
increase lasted more than 7 days after the trip. On the other hand, the general trip did not
increase human NK activity (Fig. 1B).
Effect of a forest bathing trip and the general trip on CD16+ NK cells
As shown in Fig. 2A, forest bathing trip significantly increased the number of CD16+ NK
cells, and this increase lasted more than 7days after the trip. On the other hand, although the
general trip also slightly increased CD16+ NK cells, this increase was not significant (Fig.
2B).
8
The forest bathing trip did not affect lymphocytes and WBC counts.
Effect of forest bathing trip on the percentage of cells expressing cytolytic molecules
The forest bathing trip significantly increased the percentages of GRN, perforin, and GrA/B-
expressing cells in PBL (Fig 3A). Whereas, although the general trip also slightly increased
the percentages of GRN, perforin, and GrA/B-expressing cells in PBL, these increases were
not significant (Fig. 3B).
Effect of forest bathing trip on T (CD3+) cells
Both forest bathing trip (Fig. 4A) and general trip (Fig. 4B) did not affect the number of T
cells.
Effect of forest bathing trip on adrenalin concentration in urine
The forest bathing trip significantly decreased the concentration of adrenaline in urine,
whereas, a general trip did not affect the level of adrenaline in urine, indicating that forest
bathing trip has a relaxation effect (Fig. 5A, 5B).
There were no significant differences in daily physical activity before and during the trips
(Fig. 6A, 6B). The hours of sleep were, increased during the trips compared with the control
days (Table 2), however, the difference was not significant.
Lastly, phytoncides, such as alpha-pinene, beta-pinene and limonene were detected in the
forest fields during the investigation (Table 1), and not detected in the urban area of Tokyo,
and in the city for general trip. Weather during the forest bathing trip was excellent with
9
average temperatures and humidity in the forest fields during the walking of 16.31± 0.23°C,
99.77±0.44% on day 1 in the afternoon; 19.55± 0.61°C, 78.62±3.24% on day 2 in the
morning; and 20.78± 0.42°C, 74.16±61.94% on day 2 in the afternoon, The average
temperature and humidity in urban area of Tokyo on the control day was 28.5°C, 62%,
respectively.
Discussion
We previously have found that a forest bathing trip increased human NK activity, number
of NK cells, and intracellular levels of perforin, granulysin and granzymes A/B in PBL (Li et
al., 2007). However, there are two questions remained to be resolved: one is that whether a
trip to a place without forest (general trip) also can increase NK activity? Another is that how
long the increased NK activity will be lasted after a forest bathing trip? The present study
reconfirmed that a forest bathing trip can enhance the immune response as measured by
human NK activity, and the numbers of NK cells, which is similar to our previous report (Li
et al., 2007), whereas, a trip to a place without forest (general trip) has no effect on NK
activity, indicating that forest bathing trip indeed can enhance human NK activity. Moreover,
we also found that the increased NK activity and NK cells induced by forest bathing trip
lasted more than 7 days, even 30 days after the trip. This suggests that if people go to a forest
bathing trip once a month, they can always keep NK activity in a higher level. This has a very
important significance in the health promotion from the viewpoint of preventive medicine.
NK cells kill tumor or virus infected cells by release of perforin, granzymes (Gr) (Shinkai
10
et al. 1988; Smyth et al. 2001; Beresford et al. 1997; Li et al. 2002), and granulysin (GRN)
(Okada et al. 2003; Hanson et al. 1999; Stenger et al. 1998) via the granule exocytosis
pathway. Cytotoxicity mediated by NK cells is greatly impaired in perforin-deficient mice
(Kagi et al. 1994b; Li et al. 2004). GrA plays a critical role in triggering apoptosis in target
cells either directly or via the activation of cellular caspases, and also cleaves IL-1 , theβ
nucleosome assembly protein called putative HLA-associated protein II, TAF-I , histones andβ
lamins (Smyth et al. 2001; Zhang et al. 2001ab). GrB directly cleaves the downstream caspase
substrates, nuclear matrix antigen, catalytic subunit of DNA-associated DNase inhibitor and
lamins (Smyth et al. 2001; Zhang et al. 2001a). GRN, a lytic molecule expressed by human
CTL and NK cells, is active against tumor cells and a variety of microbes. GRN can enter
target cells in the absence of perforin and induce apoptosis, although GRN and perforin
together are required to kill intracellular microbes like Mycobacteria tuberculosis (Okada et
al. 2003; Hanson et al. 1999; Stenger et al. 1998). GRN is associated with diverse activities of
NK cells and CTL in physiological and pathological settings and may be a useful marker to
evaluate the status of host cellular immunity (Ogawa et al. 2003).
In order to explore the mechanism of enhancement of NK activity by forest bathing, we
investigated the effect of forest bathing on the intracellular levels of perforin, GRN, and
GrA/B in PBL. We found that the forest bathing trip significantly increased the proportion of
perforin, GRN, GrA/B-expressing cells in PBL, which are similar to our previous report (Li et
al., 2007), whereas, general trip had no effect on perforin, GRN, GrA/B-expressing cells,
indicating that forest bathing trip indeed can increase perforin, GRN, GrA/B-expressing cells.
11
Moreover, we also found that increased perforin, GRN, GrA/B-expressing cells induced by
forest bathing trip lasted more than 7 days, even 30 days after the trip. These cytolytic
molecules contribute to NK and anti-tumor activity.
Activity of sympathetic nervous system causes adrenaline to be released into the
circulation from the adrenal cortex. Therefore, concentration of adrenaline in urine has also
been used as measures of autonomic nervous activity in response to mental demands
(Hjemdahl et al. 1984). We found that forest bathing trip significantly decreased the
adrenaline concentration in urine, however, the general trip had no effect on the adrenaline
concentration in urine, suggesting that the parasympathetic nervous system of subjects was
dominant, associated with relaxation and decreased stress (Mori et al., 2002). It has been
reported that adrenaline inhibits human NK activity (Garland et al. 2003). The increased NK
activity in forest bathing trip may be related to an attenuated stress hormone response
(adrenaline) associated with forest bathing trip. Previous studies have reported that forest
bathing reduces the concentration of cortisol in saliva, reduces prefrontal cerebral activity,
reduces blood pressure and stabilize autonomic nervous activity in humans (Miyazaki and
Motohashi 1996; Park et al., 2005, Yamaguchi et al. 2006).
Many factors, including circadian variation (Angeli 1992), physical exercise (Nieman
2000; Miles et al. 2002, Li et al., 2006b) and alcohol consumption (Ochshorn-Adelson et al.
1994, Li et al., 2006b) can affect human NK activity. In order to control the effect of circadian
rhythms on NK activity, we sampled blood at 8 am on all days. To control for the effect of
physical exercise on NK activity, we limited the walking steps during the trip to the normal
12
workday distances as monitored by a pedometer. To control the effect of alcohol on NK
activity, the subjects did not consume alcohol during the study. The sleeping hours during the
trips were a little longer than the average working days (Table 2), however, the difference was
not significant in both forest bathing trip and general trip. There are several reports addressing
the effect of sleeping hours on NK cell activity. Many reports suggest that sleep deprivation
increases human NK activity (Dinges et al. 1994; Matsumoto et al. 2001), while others
suggest that sleep deprivation decreased human NK activity (Moldofsky et al. 1989; Irwin et
al. 1994); still other studies by Kusaka et al. (1992) and Inoue et al. (1996) reported that
sleeping hours did not affect NK or LAK activity, or NK cell numbers under physiologic
conditions. In fact, we also found that there was no difference in the numbers of NK cells, nor
perforin, GRN, GrA/B-expressing cells in PBL among the subjects who slept 5, 6 or 7 hours,
respectively (Li et al. 2006b). In addition, although the sleeping hours during the general trip
were a little longer than the average working day (Table 2), however, the NK activities during
trip were almost the same with the working day, indicating that the longer sleeping hours did
not contribute to NK activity in the general trip. Taken together, although the sleeping hours
during the trips were a little longer than that on the average working day, this difference did
not affect either NK activity or numbers in the present study.
As detailed in Table 1, we detected several phytoncides such as alpha-pinene, beta-pinene
and limonene in the forest fields during the trip. We previously found that phytoncides, such
as alpha-pinene, d-limonere significantly enhanced human NK activity and increased
expression of intracellular cytolytic molecules, perforin, GrA and GRN in vitro (Li et al.
13
2006a), suggesting that phytoncide may partially contribute to the enhanced NK activity
during the forest bathing trip.
Taken together, these findings indicate that forest bathing trip can increase human NK
activity, the number of NK cells and intracellular perforin, GrA/B and GRN, and that
increased NK activity, number of NK cells and intracellular perforin, GrA/B and GRN at least
can last more than 7 days after a trip.
Acknowledgements: This work was supported partly by a research project for utilizing
advanced technologies in agriculture, forestry and fisheries of Japan (2006).
14
References
Angeli A (1992) Circadian rhythms of human NK cell activity. Chronobiologia 19:195-8.
Beresford PJ, Kam CM, Powers JC, Lieberman J (1997) Recombinant human granzyme A
binds to two putative HLA-associated proteins and cleaves one of them. Proc Natl Acad
Sci USA 94: 9285-9290.
Dinges DF, Douglas SD, Zaugg L, Campbell DE, McMann JM, Whitehouse WG., Orne EC,
Kapoor SC, Icaza E, Orne MT (1994) Leukocytosis and natural killer cell function parallel
neurobehavioral fatigue induced by 64 hours of sleep deprivation. J Clin Invest 93: 1930-
1939.
Forestry Agency of Japan (2002) http://www.rinya.maff.go.jp/toukei/genkyou/shinrin-
jinkou.htm
Garland M, Doherty D, Golden-Mason L, Fitzpatrick P, Walsh N, O'Farrelly C ( 2003) . Stress-
related hormonal suppression of natural killer activity does not show menstrual cycle
variations: implications for timing of surgery for breast cancer. Anticancer Res.
23(3B):2531-5.
Hanson DA, Kaspar AA, Poulain FR, Krensky AM (1999) Biosynthesis of granulysin, a novel
cytolytic molecule. Mol Immunol 36: 413-422.
Hirowatari Y, Ito Y, Kasai M, Takahashi H, Hayashi H (1999) Development of the automatic
catecholamine analyzer HLC-725CAII. Journal of TOSOH Research 43: 3-12 (in
Japanese with English abstract).
15
Hjemdahl P, Freyschuss U, Juhlin-Dannfelt A, Linde B (1984) Differentiated sympathetic
activation during mental stress evoked by the Stroop test. Acta Physiol Scand Suppl 527:
25-29.
Inoue C, Takeshita T, Kondo H, Morimoto K (1996) Healthy lifestyles are associated with
higher lymphokine-activated killer cell activity. Prev Med 25: 717-724.
Irwin M, Mascovich A, Gillin JC, Willoughby R, Pike J, Smith TL (1994) Partial sleep
deprivation reduces natural killer cell activity in humans. Psychosom Med 56: 493-498.
Kagi D, Vignaux F, Ledermann B, Burki K, Depraetere V, Nagata S, Hengartner H., Golstein
P (1994a) Fas and perforin pathways as major mechanisms of T cell-mediated
cytotoxicity. Science 265: 528-530.
Kagi D, Ledermann B, Burki K, Seiler P, Odermatt B, Olsen KJ, Podack ER, Zinkernagel
RM, Hengartner H (1994b) Cytotoxicity mediated by T cells and natural killer cells is
greatly impaired in perforin-deficient mice. Nature 369: 31-37.
Kawada T, Xin P, Kuroiwa M, Sasazwa Y, Suzuki S, Tamura Y (2001) Habituation of sleep to
road traffic noise as determined by polysomnography and accelerometer. J Sound Vib
242: 169-178.
Komori T, Fujiwara R, Tanida M, Nomura J, Yokoyama MM (1995) Effects of citrus
fragrance on immune function and depressive states. Neuroimmunomodulation 2: 174-
180.
Kusaka Y, Kondou H, Morimoro K (1992) Healthy lifestyles are associated with higher natural
killer cell activity. Prev Med 21: 602-615.
Li Q, Nagahara N, Takahashi H, Takeda K, Okumura K, Minami M (2002)
16
Organophosphorus pesticides markedly inhibit the activities of natural killer, cytotoxic T
lymphocyte and lymphokine-activated killer: a proposed inhibiting mechanism via
granzyme inhibition. Toxicology 172: 181-190.
Li Q, Nakadai A, Takeda K, Kawada T (2004) Dimethyl 2,2-dichlorovinyl phosphate (DDVP)
markedly inhibits activities of natural killer cells, cytotoxic T lymphocytes and
lymphokine-activated killer cells via the Fas-ligand/Fas pathway in perforin-knockout
(PKO) mice. Toxicology 204:41-50.
Li Q, Nakadai A, Matsushima H, Miyazaki Y, Krensky AM, Kawada T, Morimoto K (2006a)
Phytoncides (wood essential oils) induce human natural killer cell activity.
Immunopharmacol Immunotoxicol 28: 319-33.
Li Q, Nakadai A, Ishizaki M, Morimoto K, Ueda A, Krensky AM, Kawada T (2005) Dimethyl
2,2-dichlorovinyl phosphate (DDVP) markedly decreases the expression of perforin,
granzyme A and granulysin in human NK-92CI cell line. Toxicology 213: 107-116.
Li Q, Morimoto K, Nakadai A, Inagaki H, Katsumata M, Shimizu T, Hirata Y, Hirata K,
Suzuki H, Miyazaki Y, Kagawa T, Koyama Y, Ohira T, Takayama N, Krensky AM,
Kawada T. Forest bathing enhances human natural killer activity and expression of anti-
cancer proteins. Int J Immunopathol Pharmacol. 2007 (in press).
Li Q, Morimoto K, Nakadai, A, Qu Tianli, Matsushima H, Katsumata M, Shimizu T, Inagaki
H, Hirata Y, Hirata K, Kawada T, Lu Y, Nakayama K, Krensky AM (2006b). Healthy
lifestyles are associated with higher levels of perforin, granulysin and granzymes A/B
-expressing cells in peripheral blood lymphocytes. Prev Med., 2006 Oct 6; [Epub ahead
17
of print].
Matsumoto Y, Mishima K, Satoh K, Tozawa T, Mishima Y, Shimizu T, Hishikawa Y (2001)
Total sleep deprivation induces an acute and transient increase in NK cell activity in
healthy young volunteers. Sleep 24: 804-809.
Miles MP, Mackinnon LT, Grove DS, Williams NI, Bush JA, Marx JO, Kraemer WJ, Mastro
AM (2002) The relationship of natural killer cell counts, perforin mRNA and CD2
expression to post-exercise natural killer cell activity in humans. Acta Physiol Scand 174:
317-325.
Miyazaki Y, Motohashi Y (1996) Forest environment and physiological response. In: Agishi
Y, Ohtsuka Y (eds) New frontiers in health resort medicine. Kokoku, Sapporo, p67-77.
Moldofsky H, Lue FA, Davidson JR, Gorczynski R (1989) Effects of sleep deprivation on
human immune functions. FASEB J 3: 1972-1977.
Mori H, Nishijo K, Kawamura H, Abo T (2002) Unique immunomodulation by electro-
acupuncture in humans possibly via stimulation of the autonomic nervous system.
Neurosci Lett 320: 21-24.
Morita E, Fukuda S, Nagano J, Hamajima N, Yamamoto H, Iwai Y, Nakashima T, Ohira H,
Shirakawa T ( 2007) . Psychological effects of forest environments on healthy adults:
Shinrin-yoku (forest-air bathing, walking) as a possible method of stress reduction. Public
Health 121:54-63.
Nieman DC (2000) Special feature for the Olympics: effects of exercise on the immune
system: exercise effects on systemic immunity. Immunol Cell Biol 78: 496-501.
Ochshorn-Adelson M, Bodner G, Toraker P, Albeck H, Ho A, Kreek MJ (1994) Effects of
18
ethanol on human natural killer cell activity: in vitro and acute, low-dose in vivo studies.
Alcohol Clin Exp Res 18: 1361-1367.
Ogawa K, Takamori Y, Suzuki K, Nagasawa M, Takano S, Kasahara Y, Nakamura Y. Kondo,
S, Sugamura K, Nakamura, M, Nagata K (2003) Granulysin in human serum as a marker
of cell-mediated immunity. Eur J Immunol 33: 1925-1933.
Ohtsuka Y, Yabunaka N, Takayama S (1998) Shinrin-yoku (forest-air bathing and walking)
effectively decreases blood glucose levels in diabetic patients. Int J Biometeorol 41: 125-
127.
Okada S, Li Q, Whitin JC, Clayberger C, Krensky AM (2003) Intracellular mediators of
granulysin-induced cell death. J Immunol 171: 2556-2562.
Park BJ, Tsunetsugu Y, Kasetani T, Ohira T, Matsui N, Takayama N, Murata H, Yamaguchi
M, Yasukouchi A, Hirano H, Kagawa T, Miyazaki Y (2005) Physiological effects of
bathing in the forest atmosphere (I)—Using salivary cortisol and cerebral activity (TRS)
as an indicator—. J Physiol Anthropol Appl Human Sci 24: 188
ShinkaiY, Takio K, Okumura K (1988) Homology of perforin to the ninth component of
complement (C9). Nature 334: 525-527.
Smyth MJ, Kelly JM, Sutton VR, Davis JE, Browne KA, Sayers TJ, Trapani JA (2001)
Unlocking the secrets of cytotoxic granule proteins. J Leukoc Biol 70: 18-29.
Stenger S, Hanson DA, Teitelbaum R, Dewan P, Niazi KR, Froelich CJ, Ganz T, Thoma-
Uszynski S, Melian A, BogdanC, Porcelli SA, Bloom BR, Krensky AM, Modlin RL
(1998) An antimicrobial activity of cytolytic T cells mediated by granulysin. Science
282: 121-125.
19
Yamaguchi M, Deguchi M, Miyazaki Y ( 2006) . The effects of exercise in forest and urban
environments on sympathetic nervous activity of normal young adults. J Int Med Res.
34(2):152-9.
Zhang D, Beresford PJ, Greenberg AH, Lieberman J (2001a) Granzymes A and B directly
cleave lamins and disrupt the nuclear lamina during granule-mediated cytolysis. Proc
Natl Acad Sci USA 98: 5746-5751.
Zhang D, Pasternack MS, Beresford PJ, Wagner L, Greenberg AH, Lieberman J (2001b)
Induction of rapid histone degradation by the cytotoxic T lymphocyte protease
Granzyme A. J Biol Chem 276: 3683-3690.
20
Figure legends
Figure 1. Effect of the forest bathing trip (A) and a general trip (B) on NK activity. Data are
presented as the mean+SE ((n=12 in A and n=11 in B). ANOVA indicated that the forest
bathing trip significantly affected the NK activity (p<0.01). *: p<0.05, **: p<0.01,
significantly different from before the trip by the paired t-test. The activity values for an E/T
ratio of 20/1 are shown, and the similar results were also obtained with E/T ratios of 40/1 and
10/1.
Figure 2. Effect of the forest bathing trip (A) and a general trip (B) on the number of NK cells.
Data are presented as the mean+SE (n=12 in A and n=11 in B). ANOVA indicated that the
forest bathing trip significantly affected the percentage and number of NK cells (all p<0.01). *:
p<0.05, **: p<0.01, #: p=0.054 significantly different from before the trip by the paired t-test.
Figure 3. Effect of the forest bathing trip (A) and a general trip (B) on GRN, perforin,
GrA/B-expressing cells in PBL. Data are presented as the mean+SE (n=12 in A and n=11 in
B). ANOVA indicated that the forest bathing trip significantly affected the GRN, perforin,
GrA/B-expressing cells in PBL (all p<0.01). *: p<0.05, **: p<0.01, significantly different
from before the trip by the paired t-test.
Figure 4. Effect of the forest bathing trip (A) and a general trip (B) on the total number of T
cells. A: Data are presented as the mean+SE (n=12 in A and n=11 in B). ANOVA indicated that
21
both the forest bathing trip and general trip did not affect the number of T cells.
Figure 5. Effect of the forest bathing trip (A) and a general trip (B) on adrenaline
concentration in urine. Data are presented as the mean+SE (n=12 in A and n=11 in B).
ANOVA indicated that the forest bathing trip significantly affected the adrenaline
concentration in urine (p<0.05). *: p<0.05, significantly different from before the trip by the
paired t-test.
Figure 6. Consumption of energy of the subjects before and during the forest bathing trip (A)
and general trip (B). Data are presented as the mean+SE (n=12 in A and n=11 in B). ANOVA
indicated that there was no significant difference before and during the trips in the
consumption of energy of the subjects.
22
Table 1. Concentration of volatile substances in the air of forest fields calculated as alpha-
pinene (ng/m3)
Measuring points Field 1
Day 1 pm Field 2
Day 2
Kind of Trees Chamaecyparis Chamaecyparis
White cedar
Tricyclene 299.7 805.5
-Pineneα2,886.7 1,281.7
Camphene 375.6 486.8
-Pineneβ137.5 66.9
Myrcene 109.4 71.8
-3-Careneδ66.6 25.3
-Terpineneα43.8 26.9
p-Cymene 109.4 67.3
Limonene 111.1 48.4
-Terpineneγn.d 33.2
Terpinolene 87.5 13.4
Camphor 32.8 14.8
Bornyl acetate 54.7 43.4
n.d: not detected.
23
Table 2. Sleeping hours of the subjects before and during the forest bathing trip and general
trip (Mean±SD)
Control day
(Before trip)
Day 1
(During trip)
Day 2
(During trip)
1 Week
(After trip)
1 Month
(After trip)
Forest bathing trip 6.18±1.63 7.29±1.69 7.03±1.44 5.38±0.88 5.63±0.96
General trip 5.98±1.79 7.22±1.52 6.59±1.41
24
... Forest bathing (FB) as a medicine have become a topic of increasing importance of scientific and professional discussions across the globe in most recent times (Bach et al., 2021;Clarke et al., 2021;Farkic et al., 2021;Mathias et al., 2020;Mcewan et al., 2021;Roviello et al., 2021;Seo et al., 2021;Wen et al., 2019). When Japanese Forestry Agency coined the term "FB or Shinrin-yoku" (absorbing the forest atmosphere) in 1982, the health-improving concept was established as a broad interdisciplinary field between medicine, forestry, and sport tourism (Farkic et al., 2021;Li et al., 2007). Its recommendation to patients is often being considered as more effective for overall healing and wellbeing (Hansen et al., 2017;Li et al., 2007). ...
... When Japanese Forestry Agency coined the term "FB or Shinrin-yoku" (absorbing the forest atmosphere) in 1982, the health-improving concept was established as a broad interdisciplinary field between medicine, forestry, and sport tourism (Farkic et al., 2021;Li et al., 2007). Its recommendation to patients is often being considered as more effective for overall healing and wellbeing (Hansen et al., 2017;Li et al., 2007). Those health-improving effects of forests have been suggested to be attributed essentially among other factors to inhalation of biogenic volatile organic compounds (BVOCs) including phytoncides emitted by trees (Li et al., 2007;Roviello et al., 2021). ...
... Its recommendation to patients is often being considered as more effective for overall healing and wellbeing (Hansen et al., 2017;Li et al., 2007). Those health-improving effects of forests have been suggested to be attributed essentially among other factors to inhalation of biogenic volatile organic compounds (BVOCs) including phytoncides emitted by trees (Li et al., 2007;Roviello et al., 2021). Scientifically proven evidences have shown that exposure to forests can exert specific preventive and therapeutic health benefits such as lowering heart rate and blood pressure, reducing stress hormone production, boosting immunity, improving overall feelings, causing deep sleep and increasing expression of anti-cancer proteins, improving mental wellness and birth delivery, enhancing surgery wound healing, preventing obesity, cardiovascular disease, gallbladder disease, diabetics, and osteoporosis (Frumkin et al., 2017;Han et al., 2016;Kuo, 2015;Lee et al., 2019;Li, 2019;Li et al., 2007;Wen et al., 2019). ...
Article
Full-text available
Forest bathing (FB) as a medicine is gaining popularity across the globe but little is known about this medicine in Nigeria. Health professionals (HPs) are central to the usage of this medicine through their communications and prescriptions. Therefore, we investigated HPs willingness to acquire, share knowledge and prescribe FB in Nigeria. Cross-sectional data from the 371 HPs (Doctors, n = 215; Nurses, n = 103; Pharmacists, n = 53) from teaching and military hospitals in Port Harcourt were analyzed. About half (49.9%) of HPs were aware of the importance of forest, mostly as a source of drugs/herbs. However, only 16.4% of HPs were aware of FB of which just 4.6% had prescribed it to patients. Online internet search and seminars/conferences were dominant approaches for the acquisition and sharing of knowledge, respectively. While multinomial logistic regression results indicated age as a significant factor influencing the willingness of HPs to acquire knowledge about FB, years of experience were found as a significant factor predicting the willingness of HPs to share knowledge about FB. Gender specificity analyses indicated female HPs more willing to prescribe FB than male counterparts. The results of this study may significantly improve HPs awareness and their willingness for health communication research/practices of FB as medicine in Nigeria.
... Several studies focused on college students [1,4] and various age groups [5] are being published to verify the effectiveness of physical activity or exercise for promoting health in the current generation, and they report that participation in exercise positively affects physical and mental health while relieving stress. Additionally, scientific evidence, suggesting that exposure to the natural environment positively affects current generation's health, has recently gained significant attention in the relevant fields [6][7][8][9][10][11]. ...
... Existing studies on the positive effect of exposure to the natural environment report that patients in the hospital room, who can see plants and other natural views outside through the window, exhibit positive results for headaches, pain, complaints, and recovery period, with reduced physical pain and mental stress than those who do not see these views [1,4,6,7]. Moreover, participants reported lowered pulse rate and blood pressure and improved stability of the autonomic nervous system while observing the natural environment with plants than in the urban jungle [12]. ...
Article
Full-text available
This study aimed to investigate the effects of short-term exercise, within the natural environment or by applying similar visual stimulation, on concentration and positive psychological capital among Korean college students. Participants were 175 male college students—selected by non-probabilistic sampling—from the Korean National Police University in Asan-si, Republic of Korea, in March 2021. Participants were divided into three condition groups: the natural environmental exposure with outdoor exercise (n = 57), visual stimulation with indoor exercise (n = 58), and indoor exercise (control group; n = 60). The variables measured were concentration and positive psychological capital. Pre- and post-exercise data differences were analyzed using two-way (3 × 2) analysis of variance and Pearson’s correlation analysis, and statistical significance was set at 0.05. The results revealed a significant main effect on concentration, with lower scores post-intervention indicating positive changes in all three groups. In addition, the scores for positive psychological capital sub-factors (self-efficacy, optimism, and hope), in the groups with the natural environmental exposure with outdoor exercise and visual stimulation with indoor exercise conditions, reflected higher positive change than the indoor exercise group (p < 0.05). Furthermore, the Bonferroni post hoc test on this interaction effect revealed that the participant scores for the natural environmental exposure with outdoor exercise and visual stimulation with indoor exercise groups were positive after the exercise (p < 0.05). However, there was no interaction effect for the ego-resilience subscale (p > 0.05). Therefore, participating in short-term exercise while being exposed to a natural environment with healing characteristics or providing visual stimulation of a similar natural environment was found to positively impact the Korean college students’ concentration and positive psychological capital’s self-efficacy, optimism, and hope. Moreover, this particular intervention only affects subjective measures of well-being while not particularly influencing objective measures, such as cognitive functioning. We recommend implementing similar visual stimulation with indoor exercise for the current generation during the COVID-19 pandemic.
... A handful of studies evaluated the effect of phytoncides on improving immune function [131][132][133]. The biogenic VOCs were profoundly found to regulate blood pressure and endocrine activity, reduce blood glucose, maintain mental health by relieving stress, boost immunity, treat respiratory diseases, and fight cancer [73,93,[134][135][136][137][138][139][140][141]. Additionally, forest bathing aids patients with hypertension [142], chronic obstructive pulmonary disease [143], chronic heart failure [144,145], and chronic stroke [146]. ...
Article
Full-text available
Chemical compounds from plants have been used as a medicinal source for various diseases. Aromachology is a unique field that studies the olfactory effects after inhaling aromatic compounds. Aromatherapy is a complementary treatment methodology involving the use of essential oils containing phytoncides and other volatile organic compounds for various physical and mental illnesses. Phytoncides possess an inherent medicinal property. Their health benefits range from treating stress, immunosuppression, blood pressure, respiratory diseases, anxiety, and pain to anti-microbial, anti-larvicidal, antiseptic , anti-cancer effects, etc. Recent advancements in aromatherapy include forest bathing or forest therapy. The inhalation of phytoncide-rich forest air has been proven to reduce stress-induced immunosuppression, normalize immune function and neuroendocrine hormone levels, and, thus, restore physiological and psychological health. The intricate mechanisms related to how aroma converts into olfactory signals and how the olfactory signals relieve physical and mental illness still pose enormous questions and are the subject of ongoing research. Aroma-therapy using the aroma of essential oils/phytoncides could be more innovative and attractive to patients. Moreover, with fewer side effects, this field might be recognized as a new field of complementary medicine in alleviating some forms of physical and mental distress. Essential oils are important assets in aromatherapy, cosmetics, and food preservatives. The use of essential oils as an aromatherapeutic agent is widespread. Detailed reports on the effects of EOs in aromatherapy and their pharmacological effects are required to uncover its complete biological mechanism. This review is about the evolution of research related to phytoncides containing EOs in treating various ailments and provides comprehensive details from complementary medicine.
... Forest therapy is also understood as a method of NBI, most notably in the form of "forest bathing" or Shinrin Yoku (reflecting its origins). This involves experiencing the calm and quiet of trees for relaxation with significant benefits for both physical and mental health [19] and human immune function [20], an effect not replicated in an urban comparison [21], as well as improved self-efficacy, life satisfaction and physical activity and reduced unhealthy eating in young people [22]. The beneficial effects of NBIs appear not just attributable to increased physical activity since even short-term visits to urban greenspaces can reduce blood pressure and heart rate variability in comparison to visiting urban streets [23]. ...
Background: With the global burden of disease increasing, particularly in relation to often preventable chronic diseases, researchers and clinicians are keen to identify interventions that can mitigate ill health and enhance the psychological wellbeing of people living with long-term conditions (LTCs). It is long established that engagement with nature can support human health and wellbeing, and in recent years, nature-based interventions (NBIs) have been advanced as of potential benefit. This review thus sought to systematically appraise published evidence of the application of NBIs to address psychological wellbeing for those living with LTCs. Methods: A systematic search of three databases, PsycINFO, MEDLINE and SCOPUS, was undertaken, and the BestBETs quality assessment checklist was used to appraise methodological quality of elicited studies. Results: Of 913 studies identified, 13 studies (12 using quantitative methods, one qualitative) were used. Included papers reported use of a variety of psychological outcomes alongside more circumscribed physiological outcomes. Quality appraisal showed modest robustness, some methodological weaknesses and a dominance of application in developed countries, yet synthesis of studies suggested that reported psychological and physiological outcomes present a strong argument for NBIs having a promising and positive impact on psychological wellbeing. Conclusions: NBIs have positive psychological and physiological impacts on people with LTCs, suggesting they may be a suitable addition to current maintenance treatment. Future research should focus on minimising study bias and increasing the potential for cross-cultural applications.
Thesis
Full-text available
The aim of this thesis study is to propose a method that will set an example for all cities, and that will enable the multi-storey mass housing structures in the city of Ankara to be produced with living spaces more related to nature and to contribute positively to the existing urban environment. In order to achieve this aim, the historical process of the production of "housing" and "open and green spaces in buildings" in cities around the world and in Ankara has been examined in detail from technical and theoretical perspectives. Following this examination, the open and green spaces system in low-density city settlements was used as an example model, and a theoretical idea was developed to produce an open and green spaces system that could be included in the multi-storey mass housing buildings in the city of Ankara. The theoretical idea developed was applied on three multi-storey mass housing examples in Ankara, and the open and green spaces system proposal for multi-storey mass housing structures in the city of Ankara was revealed as a finding. Then, the system that emerged as a finding was examined and compared with the components that make up the open and green spaces system in low-density city settlements and selected examples in cities around the world. Subsequently, the changes that need to be made in the design method while the system in question was put into practice were revealed. As a final step, changes that need to be made in the field of legislation and policy proposals that need to be developed in order to put all these studies into practice were put forward. As a result, the effects of the emerged open and green spaces system on nature and people were evaluated. As a result of the evaluation, it has been observed that the system in question has revealed the potential to create positive effects on nature and people, which can be a turning point.
Chapter
Full-text available
This study aims to determine the role of stakeholder orientation, strategic capability, and joint value creation on the competitiveness of Banten’s cultural tourism destinations. This research is located in Banten Province, Indonesia. This research was conducted by distributing electronic questionnaires to 321 respondents. Furthermore, focus group discussions among stakeholders were conducted to balance and strengthen the data collected. The findings of the test results indicate that Stakeholder Orientation (OS), Strategic Capabilities (KS), and Shared Value Creation (PNB) have a significant role in the competitiveness variable of cultural tourism destinations. The results of the partial test found that the diversity of OS and KS was not significant for the competitiveness variable of cultural tourism destinations (DS). This means that in the future the OS, KS, and GNP indicators must be improved, especially the shared value creation (PNB) variable which has the biggest role.
Thesis
Die Wahrnehmung des Waldes als Raum für Muße ist im deutschsprachigen Raum eine außerordentlich populäre, die dennoch wissenschaftlich kaum erforscht ist. Die Dissertation interessiert sich für diese Wahrnehmung des Waldes, für deren Geschichte und mediale Repräsentation. Indem ihr die Annahme zugrundeliegt, dass menschliche Wahrnehmung durch medial vermittelte Muster und kollektive Imaginationen geprägt ist, fragt sie makroperspektivisch nach der inneren Logik und den Mechanismen jener kollektiv geteilten und medial vermittelten Wahrnehmungsformen in historischer Perspektive. Dafür legt die Studie zunächst die kulturhistorischen Zusammenhänge frei, in denen diese Waldwahrnehmung im Nachgang von Aufklärung und Romantik ablaufen kann. Daneben arbeitet sie soziokulturelle Kontexte und Rahmenbedingungen heraus, die sich sowohl auf den Untersuchungszeitraum beziehen, gleichzeitig aber darüber hinausweisende Erklärungen für diese spezifische Waldwahrnehmung generieren. "Muße" wird dabei begrifflich geschärft und als eng umrissene Heuristik eingesetzt, die die spezifische Waldwahrnehmung in (historischen) Quellen sichtbar werden lässt. Die Arbeit verfolgt die These, dass es sich bei der Wahrnehmung des Waldes als Raum für Muße um die Synthese einer Gegenwelt handelt, die in Dichotomie zur eigentlichen Alltagswelt steht und mit dieser eng verbunden ist. Diesem heterotopischen Potenzial des Waldes folgt die Arbeit narrativartig und zeichnet nach, dass und wie diese Perspektive in der westlichen Zivilisationsgeschichte seit Jahrtausenden dominiert und sich auch in der hier untersuchten Waldwahrnehmung niederschlägt. Der Wald ist ausdrücklich kein speziell eingerichteter Mußeraum, wie bspw. ein Park oder ein Andachtsraum, sondern ein unter ökologischen und ökonomischen Gesichtspunkten gestaltetes materiales Substrat. Um diesem Spannungsfeld von forstlicher Gestaltung und nicht-forstlicher Waldwahrnehmung Rechnung zu tragen, wird der Wald raumtheoretisch als sozialer Raum verstanden. Dazu wird ein Modell entwickelt, dass diese neue und innovative Sichtweise ermöglicht. Mit dem Schwerpunkt auf der zweiten Hälfte des 19. Jahrhunderts und dem Fokus auf eine bildungsbürgerliche Perspektive wird anhand des enorm populären Massenblattes "Die Gartenlaube" aufgezeigt, wie der Wald im Zusammenhang mit der Wahrnehmung als Mußeraum auf verschiedenen Ebenen idyllisiert wird. Der Zusammenhang zwischen dieser spezifischen Naturvorstellung und der Muße wird herausgearbeitet und das analytische Potenzial dieser Feststellung abschließend fruchtbar gemacht, um die Fortschritts- und Zivilisationskritik zu belegen, die mit dieser Sicht auf den Wald eng verbunden ist.
Chapter
This chapter presents the relevant studies on the short- and long-term health effects of forest bathing and forest therapy. They are scientifically prepared and evaluated. A distinction is made between the relaxing and restorative effects as well as the psychological and physical effects, also on various disease patterns.
Article
Full-text available
The influence of "shinrin-yoku" (forest-air bathing and walking) on blood glucose levels in diabetic patients was examined. Eighty-seven (29 male and 58 female) non-insulin-dependent diabetic patients [61 (SEM 1) years old] participated in the present study. Shinrin-yoku was performed nine times over a period of 6 years. The patients were divided into two parties. They then walked in the forest for 3 km or 6 km according to their physical ability and/or the existence of diabetic complications. The mean blood glucose level after forest walking changed from 179 (SEM 4) mg.100 ml-1 to 108 (SEM 2) mg.100 ml-1 (P < 0.0001). The level of glycated haemoglobin A1c also decreased from 6.9 (SEM 0.2)% (before the first shinrin-yoku) to 6.5 (SEM 0.1)% (after the last shinrin-yoku; P < 0.05). Blood glucose values declined by 74 (SEM 9) mg.100 ml-1 and 70 (SEM 4) mg.100 ml-1 after short- and long-distance walking respectively. There was no significant difference between these values. Since the forest environment causes changes in hormonal secretion and autonomic nervous functions, it is presumed that, in addition to the increased calorie consumption and improved insulin sensitivity, walking in a forest environment has other beneficial effects in decreasing blood glucose levels.
Article
Full-text available
The effect of 40 h of wakefulness on a variety of immunological parameters in the peripheral blood from 10 normal male subjects was studied. Sleep deprivation led to enhanced nocturnal plasma interleukin 1-like and interleukin 2-like activities. The rise in nocturnal response of lymphocytes to pokeweed mitogen stimulation during a normal 24 h sleep-wake cycle was delayed by sleep deprivation, but the response to the phytohemagglutinin mitogen was unaffected. With resumed nocturnal sleep, there was a prolonged decline in natural killer cell activity (measured as spontaneous cytolytic activity for human tumor cells) and return of an increased response to pokeweed mitogen. The altered patterns in immune functions occurred independently of the cortisol circadian rhythm, which remained unchanged.
Article
Full-text available
Two molecular mechanisms of T cell-mediated cytotoxicity, one perforin-based, the other Fas-based, have been demonstrated. To determine the extent of their contribution to T cell-mediated cytotoxicity, a range of effector cells from normal control or perforin-deficient mice were tested against a panel of target cells with various levels of Fas expression. All cytotoxicity observed was due to either of these mechanisms, and no third mechanism was detected. Thus, the perforin- and Fas-based mechanisms may account for all T cell-mediated cytotoxicity in short-term in vitro assays.
Article
A gas chromatographic—mass spectrometric technique for the analysis of trace concentrations (sub-ppb*) of monoterpenes in the air is descrbed. Samples wre collected on Tenax GC adsorbent and thermally desorded onto the analytical column for separation and detection by selected ion monitoring. Experimental results are given for different kinds of forests in the Tsukuba district of Japan. The diurnal variation of the monoterpene concentration in the atmosphere was also measured in a pine forest.
Article
Chronic use of ethanol may cause a variety of immunological abnormalities in humans. In this study, we have determined the effects of an acute, low dose of ethanol (0.5 g/kg), administered either intravenously or orally, to normal, nonalcoholic male volunteers, on natural killer cell (NK) activity. We have also examined the effects of a 4-hr incubation with ethanol, in concentrations ranging from 0 to 320 mg/dl, on human NK activity in vitro. NK activity was measured by the 51Cr release assay technique in all of these studies, using peripheral blood mononuclear cells prepared from blood obtained from healthy, nonalcoholic volunteers. Eight subjects received ethanol in vivo; cells from nine subjects were used for the in vitro studies. Blood ethanol concentrations were determined at multiple time points before and after ethanol administration for the in vivo studies; for the in vitro studies, ethanol concentrations were measured from each assay sample both before and after the incubation period. Gas chromatography was used for determinations of both blood alcohol and medium ethanol concentrations. Results of the in vivo studies showed that a single dose of ethanol (0.5 g/kg), administered either intravenously (with resultant peak blood levels transiently up to 89 mg/dl) or orally (with resultant peak blood levels transiently up to 40 mg/dl at the time of the NK assay), did not alter NK activity. However, results of the in vitro studies showed a significant dose-dependent decrease (p < 0.001) in NK activity when ethanol exposure was sustained for 4 hr at concentrations of 80 mg/ dl and above. We conclude that one of the possible causes for a higher incidence of certain viral infections and malignant tumors among chronic alcoholics may be due, in part, to this observed direct effect of ethanol on NK cytotoxicity.
Article
The habituation of human sleep to a noisy environment was investigated by polysomnography (PSG), a wrist activity device (Actiwatch®), subjective evaluation and a performance test on the following morning. Eleven young male students slept for 17 nights in a sleep laboratory. PSG on the first, fourth, fifth, ninth, 14th, and 17th nights was judged visually. Four of the subjects were continuously monitored by the wrist activity device. From the fifth to 14th nights, there was exposure to road traffic noise all-night long, and consecutive experiments were conducted from the fifth to 17th nights. Agreement of sleep/wake assessment for Actiwatch®and PSG was 88·4%, on average, based on the data for 24 nights. Pearson's correlation coefficient of TST for Actiwatch®and sleep PSG was 0·848. Habituation to noise by wrist movement, sleep latency by PSG, and activity of mental muscles was not recognized. The association between wrist activity and mental muscle activity was significant for three subjects out of four (r=0·56, 0·81, 0·71, respectively). Percentages of positive wrist movement in each sleep stage, such as the 3+4 stages, REM stage and stage MT, were compared with those in other stages. Wrist activity in Stage REM was significantly more frequent than that in other stages for the three subjects. Wrist movement in Stage MT was significantly more frequent than in other stages for the three subjects. REM latency, REM cycle, and five factors of subjective sleep, from the Oguri–Shirakawa–Azumi questionnaire (SQ), showed significant differences by analysis of variance for repeated measurements. When change from the 4th night was checked, sleepiness, worry, integrated sleep feeling and sleep initiation by SQ showed habituation of sleep to noise. Namely, sleep quality recovered to the level on a silent night by the fifth noisy night during the experiment. There is thus a habituation of sleep to noise when a subjective evaluation of sleep, such as the SQ, is used.
Article
To investigate the association of individual lifestyle with immune response against tumors, we assayed peripheral blood lymphocytes of 62 healthy males ranging in age from 30 to 60 years for natural killer (NK) cell activity, which is the first line of defense against tumors, and for frequencies of NK cell subsets. The NK cell activity was determined by 51Cr release assay, and NK cell subsets were counted using surface antigens (CD16, CD57) which recognize NK cell subgroups with different cytolytic potentials. Subjects were classified into groups reporting good, moderate, and poor lifestyles according to their responses on a questionnaire regarding eight health practices (tobacco smoking, alcohol consumption, hours of sleep, physical exercise, eating breakfast, balanced nutrition, hours of work habits, and mental stress). Individuals reporting good lifestyle habits were found to have the highest NK cell activity and it was significantly higher than the NK cell activity in those reporting poor lifestyle habits. Those reporting good health practices regarding smoking and physical exercise showed significantly higher NK cell activity at an effector-to-target-cell ratio of 40:1. The higher NK cell activity among individuals reporting good lifestyle practices may reflect an increase in the cytolytic potential of NK cell activity within the CD16+, CD57- subset.
Article
Perforin-deficient mice have been generated by homologous recombination to determine whether the effects of CD8+ cytolytic T cells and natural killer cells are mediated by pore formation involving perforin. These mice are viable and fertile and have normal numbers of CD8+ T cells and natural killer cells which do not lyse virus-infected or allogeneic fibroblasts or natural killer target cells in vitro. The mice fail to clear lymphocytic choriomeningitis virus and they eliminate fibrosarcoma tumour cells with reduced efficiency. Perforin is therefore a key effector molecule for T-cell- and natural killer-cell-mediated cytolysis.
Article
In our previous experiments on animals evidence was found that citrus fragrance can restore the stress-induced immunosuppression, suggesting that citrus fragrance may have an effect on restoring the homeostatic balance. Since a dysregulation of the neuroendocrine and immune function is thought to be associated with psychosomatic or psychiatric disorders an attempt was made to restore their mental health by stimulation of one of the sensory systems. Fragrance (citrus was our choice) which comforts through stimulation of the olfactory system was applied to depressive patients. It was given to 12 depressive subjects and the results indicated that the doses of antidepressants necessary for the treatment of depression could be markedly reduced. The treatment with citrus fragrance normalized neuroendocrine hormone levels and immune function and was rather more effective than antidepressants.
Article
To investigate the association between lifestyle factors and immune responses to tumors, we determined lymphokine-activated killer (LAK) cell activity and proportions of lymphocyte subsets in 54 healthy males. LAK cell activity was determined by 51Cr release assay. The proportions of natural killer cells (CD3-16+56-, CD3-16-56+ or CD3-16+56+ cells), helper/ inducer T cells (CD4+8-), and cytotoxic/suppressor T cells (CD4-8+) in lymphocytes were also determined by flow cytometry. Subjects were classified into two groups, good or poor overall lifestyle, according to their answers on a questionnaire regarding eight health practices (cigarette smoking, alcohol consumption, physical exercise, mental stress, sleeping pattern, nutritional balance, eating breakfast, working pattern). Subjects with good health practices regarding smoking showed significantly higher LAK cell activity. They also showed a significantly higher proportion of natural killer cells and a lower proportion of helper/inducer T cells. LAK cells activity was significantly higher in subjects with a good overall lifestyle than in those with a poor overall lifestyle after controlling for the effects of smoking. There were no significant differences in the proportions of lymphocyte subsets between the two lifestyle groups. Lifestyle factors are associated with LAK cell activity and the proportion of lymphocyte subsets.