Hitoshi Mukohyama

Mito Red Cross Hospital, Mito-shi, Ibaraki, Japan

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Publications (27)46.34 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Chondrogenesis and osteogenesis during fetal development and postnatal growth constitute one of the most interesting and complicated subjects in biology. In this study, bone marrow mesenchymal stem cells (MSCs) were embedded in collagen gel, cultured in chondrogenic or osteogenic medium, and compared morphologically during chondrogenic and osteogenic differentiation sequentially by light and electron microscopy and immunohistochemical examination. Before induction, the MSCs were dispersed and round in the collagen gel. At day 1, MSCs with a large number of short processes produced extracellular fibers whose immunoreactivity was positive for collagen type I. At day 3, the shape of MSCs changed from round to elongated. Gap junctions positive for connexin 43 were also observed. At day 7, remarkable morphological differences were first observed during chondrogenesis and osteogenesis. The shape of MSCs changed to polygonal without cell processes during chondrogenesis, while MSCs remained spindle shaped with long processes during osteogenesis. Concurrently, collagen type II during chondrogenesis and osteocalcin during osteogenesis were first detected. At day 21, chondrogenesis and osteogenesis of the MSC/collagen composite further progressed, respectively. In vitro chondrogenesis and osteogenesis using an MSC/collagen composite clarified the morphological differences.
    Medical Molecular Morphology 01/2013; · 1.17 Impact Factor
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    ABSTRACT: Many papers have been published on surgical mandibulectomy and reconstruction. However, only a few reports refer to masticatory function after prosthodontic treatment in mandibulectomy patients. The aim of this study was to investigate the masticatory function of mandibulectomy patients. Twenty-three subjects (10 males and 13 females, with an average age of 63 years) participated in this study: 11 subjects who had undergone unilateral marginal mandibulectomy, six subjects with unilateral segmental mandibulectomy with reconstruction and six subjects with hemimandibulectomy without reconstruction. Mixing Ability Index (MAI) was used to measure masticatory function on the non-defect side and on the defect side with a prosthesis installed. Comparisons were carried out among the marginal, segmental and hemimandibular groups and between the non-defect side and the defect side. Consequently, our study indicates these results. On the non-defect side, a significant difference was found between the marginal and the segmental groups, and between the marginal and the hemimandibular groups. In the marginal and the segmental groups, a significant difference was found between the non-defect and the defect sides. In conclusion, our study suggests that MAI is an adequate tool to study the masticatory function in mandibulectomy patients, the masticatory function of the mandibulectomy patients is more impaired than that of the ordinary removable partial denture patients, and that surgical intervention affects the masticatory function on not only the defect side but also the non-defect side in mandibulectomy patients.
    Journal of Oral Rehabilitation 07/2008; 35(6):408-14. · 2.34 Impact Factor
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    Mihoko Haraguchi, Hitoshi Mukohyama, Hisashi Taniguchi
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    ABSTRACT: An interim obturator prosthesis is required for the restoration of speech, deglutition, and improvement of esthetics after maxillectomy. This article describes a simple method for fabricating the interim obturator prosthesis by duplicating the patient's teeth and palate. The interim obturator prosthesis fabricated by duplication of the presurgical appearance and contour may be more acceptable to the patient.
    Journal of Prosthetic Dentistry 07/2006; 95(6):469-72. · 1.72 Impact Factor
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    ABSTRACT: The aim of the present study was to investigate whether the vibratory characteristics of obturator prostheses are affected by bulb design, i.e.: the hollow or buccal flange type, and different lateral and medial bulb heights. Buccal flange and hollow bulb obturator prostheses were fabricated with two different lateral bulb wall heights and two different medial bulb wall heights. Ultimately, eight obturator prostheses were prepared for evaluation of their vibratory characteristics. The frequency-response functions were recorded on an FFT analyzer to identify their vibratory characteristics. A transient response simulation was carried out in which an impact was applied to the non-defect side. The decay rate, damping time and maximum amplitude of the retainers were statistically analysed by anova with Scheffé's test (P < 0.05). The decay rate of every buccal flange type was higher and damping time was shorter than those of every hollow type, except between a pair with low lateral and low medial bulb walls. The maximum amplitude values of four obturators with low medial bulb walls were significantly lower than those of four obturators with high medial walls. The buccal flange obturator prosthesis with high lateral and low medial walls showed the maximum decay rate and the minimum amplitude of the retainers on molars. Vibration analysis suggests that a buccal flange obturator prosthesis with high lateral and low medial walls is preferable.
    Journal of Oral Rehabilitation 02/2006; 33(1):43-51. · 2.34 Impact Factor
  • Prosthodontic Research & Practice 01/2006; 5(1):21-25.
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    ABSTRACT: Rehabilitation of patients who have undergone bilateral maxillectomy is difficult because of extensive loss of bone and soft tissue. In this clinical report, prosthodontic rehabilitation of oral function in a bilateral maxillecitomy patient combined with a new fibular osteocutaneous flap, which was designed to have two oronasal slits for the retention of an obturator prosthesis, was described. A 58-year-old man with a maxillary alveolar carcinoma underwent bilateral maxillectomy. The defect was reconstructed using a vascularized fibular bone wrapped circumferentially with a peroneal flap, which was fixed with miniplates between the right malar prominence and cut edge of the left zygoma remaining two slits anterior and posterior to the graft. Two and half weeks after the surgery, a delayed surgical obturator was delivered and an obturator prosthesis was delivered 6 weeks after the surgery. This obturator prosthesis could be extended into the slits to engage the tissue undercuts, and was stable during use. Mastication, deglutition, articulation and the mid-facial profile of the patient were rehabilitated. After installation of the obturator prosthesis, relining of the prosthesis base was carried out alongside the healing process of the graft, and adjustment of occlusions and high-pressure spots was carried out. No clinical disorders were observed either in the grafted tissue or the obturator prosthesis with a 3-year prognosis. Newly designing a fibular osteocutaneous flap combined with tissue-borne obturator prosthesis is one successful approach to the restoration of oral function, and increases the patient's quality of life after bilateral maxillectomy.
    Journal of Oral Rehabilitation 08/2005; 32(7):541-4. · 2.34 Impact Factor
  • Maxillofacial Prosthetics. 01/2005; 28(2):46-58.
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    ABSTRACT: An intraoral prosthesis was fabricated to restore more normal contour to a patient's lower lip that was compromised following a marginal mandibulectomy performed to eradicate a malignant neoplasm. The surgical resection compromised the lower lip on the affected side because the marginal mandibular branch of the facial nerve was damaged during the surgical resection. The prosthesis successfully restored the lost lip support, reduced the incidence of lip biting, and improved the patient's oral competency. This clinical report describes the procedure for making an intraoral lip plumper prosthesis to improve patient esthetics and oral function.
    Journal of Prosthetic Dentistry 08/2004; 92(1):23-6. · 1.72 Impact Factor
  • Hitoshi Mukohyama, Mariko Sasaki, Hisashi Taniguchi
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    ABSTRACT: Functional rehabilitation of maxillectomy patients is important in reestablishing the patients' quality of life. This article describes a prosthodontic technique that allows for modification of a surgical obturator clinically, allowing rapid restoration of speech and deglutition.
    Journal of Prosthetic Dentistry 07/2004; 91(6):518-20. · 1.72 Impact Factor
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    ABSTRACT: The purpose of the present study was to measure tongue pressure with the aim of characterizing the pattern of linguopalatal contact during articulating glossal sounds in normal subjects and glossectomy patients. Tongue pressures against the palate were evaluated in 13 normal subjects and 5 glossectomy patients by using three parameters: the duration from the onset of linguopalatal contact to the time of maximum pressure, the maximum pressure, and anterior posterior ratio of the maximum pressure. Three glossal sounds, [ti], [t [symbol: see text] i], and [[symbol: see text] i], which have tendency of mishearing in glossectomy patients, were selected for test sounds. A unique characteristic was demonstrated in normal subjects. The score of the maximum pressure showed an apparent order among the three sounds, while the durations revealed the opposite order. Anterior posterior ratio of the maximum pressure also showed some relationship among three sounds. In glossectomy patients, these characters were not found. The loss of tongue volume or deterioration of tongue mobility causes these results.
    Journal of medical and dental sciences 04/2004; 51(1):19-25.
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    ABSTRACT: The purpose of this study is to evaluate the masticatory muscle activity and mandibular movement during function in marginal mandibulectomy patients. Three marginal mandibulectomy patients and three healthy subjects participated in this study. The activities of the temporalis (TA) and masseter muscles (MM) on the normal and resected sides during maximum voluntary clenching (MVC) and gum chewing (Gch), and mandibular movement during Gch were analyzed. Paired t-test, Student's t-test and one-way ANOVA were performed at P < 0.05. For MVC, integrated EMG (iEMG) in patients was lower than in healthy subjects. When iEMG of each muscle activity in patients was compared, TA activity on the resected side was greater than that of MM. There were no differences between the normal and resected sides in TA or MM. For Gch, no differences in iEMG, burst or chewing time were found between patients and healthy subjects. MVC was greater than Gch in healthy subjects, but no difference was found in patients. The range of mandibular movement along the X axis in patients was greater than in healthy subjects. Within the limitations of this study, EMG activity in patients during MVC was remarkably lower than that in healthy subjects, and altered mandibular movement was observed.
    Journal of medical and dental sciences 12/2003; 50(4):257-64.
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    ABSTRACT: Although previous studies have shown that maxillary molar extraction in ovariectomized (OVX) animals causes mandibular loss of bone, it is still questionable as to whether estrogen deficiency affects mandibles with functional occlusion. To answer this question, 13-week-old female Sprague-Dawley rats were bilaterally OVX or sham-operated. After 109 days, the bone mineral density (BMD) of the femurs and mandibles was measured using dual-energy X-ray absorptiometry (DEXA) and peripheral quantitative computed tomography (pQCT). In DEXA analysis, although the BMD of the total mandible of the OVX rats was similar to that of the sham-operated rats, the BMD of the condylar region in the OVX rats had decreased by 12.5%. In pQCT analysis, decrease in trabecular BMD of the mandibular bone was detectable but low in the molar region (maximal 13%), whereas no difference was seen in cortical BMD. In the femurs, the trabecular bone prominently decreased in OVX rats (30% decrease in pQCT analysis) as previously reported. This study revealed regional differences in the mandibular bone decrease in OVX rats. Although the mechanism of low susceptibility of the mandible to estrogen-deficient conditions remains unknown, it is likely that mechanical stress derived from functional occlusion is preventing bone loss in this pathological condition. Furthermore, this study demonstrated the advantage of pQCT in analyzing rat mandibular bone.
    Oral Diseases 02/2003; 9(1):24-8. · 2.38 Impact Factor
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    ABSTRACT: The effects of high extracellular calcium (high Ca) in the local microenvironment on osteoclasts, osteoclast progenitors and stromal cells are not fully understood. We examined high Ca effect on osteoclastogenesis in mouse bone marrow cell culture. Mouse bone marrow cells were cultured for up to 6 days in the medium supplemented with 1, 25(OH)2 vitamin D3 (D3). High Ca treatment at the early stage of culture (the initial 24 hours) reduced the number of tartrate resistant acid phosphatase-positive multinuclear cells (TRAP(+)MNCs). This treatment slightly up-regulated the mRNA expressions of receptor activator of NF-(B ligand (RANKL), RANK and osteoprotegerin (OPG). This inhibitory effect on the formation of TRAP(+)MNCs was recovered by RANKL. In contrast, high Ca treatment at the later stage of osteoclastogenesis (the last 2 days of culture) stimulated the formation of TRAP(+)MNCs, increased RANKL and RANK mRNA expressions and decreased OPG mRNA. High Ca at neither the early nor the later stage of culture affected the total number of adherent cells and the mRNA expression of alkaline phosphatase and osteopontin. In conclusion, high Ca affects osteoclastogenesis in a manner depending on the stage of osteoclastogenesis, which is partly mediated via the RANKL-RANK-OPG regulatory system.
    Journal of medical and dental sciences 01/2003; 49(4):109-20.
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    ABSTRACT: The purpose of this study was to investigate the effect on the vibratory characteristics of a cast hollow obturator prosthesis retainer when varying its bulb height. Bulb parts with high (H), middle (M), and low (L) lateral walls were prepared. A Vibration Generator was used to excite the three obturators, while a Laser-Doppler Vibrometer was employed to detect the vibrations at specified measurement points. The frequency response functions of each obturator were recorded on an FFT analyzer to enable their modal shapes to be identified. In addition, transient response simulations were carried out and the decay rate (DR) and the maximum amplitude (MA) of the rest and clasp parts of each obturator were obtained. These were statistically analyzed by ANOVA and Fisher's PLSD test (p < 0.01). The modal shapes were almost the same in all obturators. Significant differences were found in DR in all pairs among the three obturator prostheses, with the DR of the L type being the highest. On the other hand, there were no significant differences in MA. We conclude that the L type is preferable from the standpoint of its vibratory characteristics.
    Journal of medical and dental sciences 12/2002; 49(4):121-8.
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    ABSTRACT: Interleukin-11 (IL-11) is a stromal cell-derived cytokine that can enhance osteoclast formation and stimulate bone resorption. In the present study, the characteristics of the resorptive effect of IL-11 in mouse calvarial bones were investigated. Both recombinant mouse IL-11 and human IL-11 caused concentration- and time-dependent stimulations of (45)Ca release from prelabeled mouse calvariae. Half-maximal responses were obtained at 0.7 ng/mL (approximately 40 pmol/L). Mouse and human IL-11 also stimulated release of (3)H from [(3)H]-proline-labeled bones. The magnitude of the (45)Ca and (3)H release (1.4-1.6-fold) caused by a maximally effective concentration of IL-11 was less than the stimulation (2.5-4.0-fold) elicited by a maximum concentration of parathyroid hormone (PTH). Release of (45)Ca by IL-11 was unaffected by the mitotic inhibitors, hydroxyurea and aphidicolin. In addition to resorption of bone, IL-11 caused a small (1.5-2.0-fold) enhancement of prostaglandin E(2) (PGE(2)) biosynthesis in calvariae, but had no effect on the mRNA expression of cyclooxygenase-1 and -2, or cytosolic phospholipase A(2). Indomethacin and flurbiprofen abolished the formation of PGE(2) and partially reduced (45)Ca release stimulated by IL-11. When either mouse interleukin-4 (IL-4) or interleukin-13 (IL-13) was added to calvariae treated with IL-11, (45)Ca release was inhibited. Resorption caused by IL-11 was also inhibited by both anti-mouse glycoprotein 130 (gp130) and an antibody neutralizing IL-11, but these agents had no effect on (45)Ca release caused by PTH or 1,25(OH)(2)vitamin D(3) (D(3)). Real-time, quantitative polymerase chain reaction (PCR) analysis (TaqMan PCR) and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) demonstrated that IL-11 caused concentration-dependent enhancements of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) mRNA, without affecting the mRNA expression of RANK. Mouse RANKL stimulated (45)Ca release in the calvarial bones. The stimulatory effects of RANKL and IL-11 were inhibited by mouse OPG. These data demonstrate that IL-11 stimulates osteoclastic resorption in mouse calvariae by mechanisms that are independent of cell proliferation; partially dependent on prostaglandin biosynthesis; sensitive to inhibition by IL-4, IL-13, and OPG; and associated with enhanced expression of RANKL and OPG. In addition, IL-11 was not found to play an essential role in resorption stimulated by other calciotropic agents in calvariae.
    Bone 08/2002; 31(1):242-51. · 4.46 Impact Factor
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    ABSTRACT: The aim of the study was to characterize the acoustics of vowel articulation in maxillectomy patients. Digital acoustic analysis of five vowels, /a/, /e/, /i/, /o/ and /u/, was performed on 12 male maxillectomy patients and 12 normal male individuals. A simple set of acoustic descriptions called the first and second formant frequencies, F1 and F2, were employed and calculated based on linear predictive coding. The maxillectomy patients had a significantly lower F2 for all five vowels and a significantly higher F1 for only /i/ vowel. From the data plotted on an F1-F2 plane in each subject, we determined the F1 range and the F2 range, which are the differences between the minimum and the maximum frequencies among the five vowels. The maxillectomy patients had a significantly narrower F2 range than the normal controls. In contrast, there was no significant difference in the F1 range. These results suggest that the maxillectomy patients had difficulty in controlling F2 properly. In addition, the speech intelligibility (SI) test was performed to verify the results of this new frequency range method. A high correlation between the F2 range and the score of SI test was demonstrated, suggesting that the F2 range is effective in evaluating the speech ability of maxillectomy patients.
    Journal of Oral Rehabilitation 08/2002; 29(7):649-56. · 2.34 Impact Factor
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    ABSTRACT: The presence of cholesterol crystals, macrophages, and foreign giant cells has been associated with impaired bone healing of periapical lesions. Therefore, we investigated whether macrophages exposed to cholesterol crystals can release factors changing the activity of bone-resorbing osteoclasts. Mouse peritoneal macrophages treated with cholesterol crystals in vitro produced factor(s) that stimulated the release of 45Ca and 3H from mouse calvariae pre-labeled with 45Ca(CaCl2) or [3H]-proline, respectively. No bone-resorbing activity was released by epithelial cells, fibroblasts, or osteoblasts exposed to cholesterol crystals. Interleukin-1 receptor antagonist protein and antiserum neutralizing mouse interleukin-1alpha (IL-1alpha) inhibited 45Ca release induced by cholesterol-activated macrophages. The addition of cholesterol to the macrophages augmented the release of IL-1alpha protein and the expression of IL-1alpha mRNA. These findings indicate that frustrated phagocytosis by macrophages exposed to cholesterol crystals results in release of factors stimulating osteoclastic bone resorption, primarily due to increased transcription of the IL-1alpha gene.
    Journal of Dental Research 02/2002; 81(1):11-6. · 3.83 Impact Factor
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    ABSTRACT: The aim of this study was to analyze the vibratory characteristics in the maxillary dentition of 4 cleft lip and palate (CLP) patients before and after bone grafting. First, the central incisor on the noncleft side was impacted with an impact hammer, and the responses were received using an acceleration sensor from the teeth between the upper first molars on both sides. The transfer functions were then obtained from each measurement point using a fast Fourier transform analyzer. Finally, a computer analysis and simulation were performed based on the measured transfer functions to obtain the natural frequency, modal shape, decay rate (DR) and maximum displacement (MDP). Before bone grafting, distinct phase differences between the major and minor dental arches (MDA and mDA) were observed in the modal shapes. After surgery, however, both the MDA and mDA vibrated in phase. These results were identical in all subjects. The MDPs of the central incisors conspicuously decreased after bone grafting in 3 subjects. From the standpoint of vibratory characteristics, this study indicated that bone grafting had a favorable effect on prosthodontic treatment using a fixed prosthesis across the cleft in CLP patients.
    Journal of medical and dental sciences 10/2001; 48(3):87-94.
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    ABSTRACT: Three distinct complementary DNAs for vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) re- ceptors have been cloned and designated VIP-1 receptor (VIP-1R), VIP-2 receptor (VIP-2R), and PACAP receptor (PACAP-R). In the present study, we have characterized the binding sites on primary mouse cal- varial osteoblasts for VIP and related peptides. By analyzing the cAMP response, the rank order of response observed was PACAP 38 . PACAP 27 . helodermin . VIP . helospectin . glucagon . PHI ... secretin. The VIP-2R/PACAP-R antagonist, PACAP 6-38, inhibited both VIP- and PACAP-stimulated cAMP formation. Binding studies using an atomic force microscopy (AFM) technique showed high affinity binding for VIP and PACAP 38, but not for secretin. Radioligand binding studies using 125I-VIP and 125I-PACAP 38 demonstrated a more specific and higher affinity binding for PACAP 38 than for VIP. Secretin failed to inhibit both 125I-VIP and 125I-PACAP 38 binding. RT-PCR demonstrated that undifferentiated mouse calvarial osteoblasts express messenger RNA for VIP-2R, but not for VIP-1R or PACAP-R. When the osteoblasts were cultured for 20 days to induce bone noduli formation, VIP-1R, in addition to VIP-2R, were expressed when the nodules started to min- eralize at 12 days. Taken together, these data demonstrate that mouse calvarial osteoblasts express functional VIP-2R with higher affinity binding for PACAP than for VIP and that the VIP-1R expression is induced during osteoblastic differentiation. (Endocrinology 142: 339- 347, 2001)
    Endocrinology 01/2001; 142(1):339-347. · 4.72 Impact Factor
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    ABSTRACT: Three distinct complementary DNAs for vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) receptors have been cloned and designated VIP-1 receptor (VIP-1R), VIP-2 receptor (VIP-2R), and PACAP receptor (PACAP-R). In the present study, we have characterized the binding sites on primary mouse calvarial osteoblasts for VIP and related peptides. By analyzing the cAMP response, the rank order of response observed was PACAP 38 > PACAP 27 > helodermin > VIP > helospectin > glucagon > PHI > secretin. The VIP-2R/PACAP-R antagonist, PACAP 6-38, inhibited both VIP- and PACAP-stimulated cAMP formation. Binding studies using an atomic force microscopy (AFM) technique showed high affinity binding for VIP and PACAP 38, but not for secretin. Radioligand binding studies using (125)I-VIP and (125)I-PACAP 38 demonstrated a more specific and higher affinity binding for PACAP 38 than for VIP. Secretin failed to inhibit both (125)I-VIP and (125)I-PACAP 38 binding. RT-PCR demonstrated that undifferentiated mouse calvarial osteoblasts express messenger RNA for VIP-2R, but not for VIP-1R or PACAP-R. When the osteoblasts were cultured for 20 days to induce bone noduli formation, VIP-1R, in addition to VIP-2R, were expressed when the nodules started to mineralize at 12 days. Taken together, these data demonstrate that mouse calvarial osteoblasts express functional VIP-2R with higher affinity binding for PACAP than for VIP and that the VIP-1R expression is induced during osteoblastic differentiation.
    Endocrinology 01/2001; 142(1):339-47. · 4.72 Impact Factor

Publication Stats

311 Citations
46.34 Total Impact Points

Institutions

  • 2013
    • Mito Red Cross Hospital
      Mito-shi, Ibaraki, Japan
  • 2001–2008
    • Tokyo Medical and Dental University
      • Department of Maxillofacial Prosthetics
      Edo, Tōkyō, Japan
  • 2006
    • The University of Tokyo
      • Center for Health Service
      Tokyo, Tokyo-to, Japan
  • 1999–2002
    • Umeå University
      • Department of Odontology
      Umeå, Västerbotten, Sweden