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Publications
Publications (89)
Objective: The performance of the Sudoscan technology for diagnosing diabetic polyneuropathy (DPN) was evaluated against the quantitative sudomotor axon reflex test (QSART). Furthermore, the association of Sudoscan with two clinical neuropathy scoring systems was evaluated.
Methods: Forty-seven patients with type 2 diabetes (20 without DPN, 27 with...
We aimed to explore the effects of bilateral subthalamic nucleus stimulation and levodopa on cardiovascular autonomic function in Parkinson’s disease. Twenty-six Parkinson’s disease patients with bilateral subthalamic nucleus stimulation in a stable state were tested under stimulation off and dopaminergic medication off (OFF-OFF), stimulation on an...
Objective: It is well-known that initiation of fingolimod induces a transient decrease of heart rate. However, the underlying cardiac autonomic regulation is poorly understood. We aimed to investigate the changes of autonomic activity caused by the first dose of fingolimod using a long-term multiple trigonometric spectral analysis for the first tim...
Background and objective:
While there is strong evidence linking obesity with increased sympathoneural activity, involvement of the adrenal medulla is less clear. We therefore investigated adrenal medullary function under fasting and feeding conditions in normal weight (NW, n=33), overweight (OW, n=28) and obese (OB, n=36) adults (59% women).
Sub...
Sympathetic system hyperactivity and depression are related to cardiac remodelling in Black men. We investigated whether sympathetic system hyperactivity and depressive symptoms are related to retinal vascular dysregulation. A total of 76 Black and 83 White men (23–68 years of age) from the SABPA study were included. Depressive symptoms, 24h pulse...
Spontaneous BRS estimates may considerable vary according to the technique of blood pressure and heart rate assessment. To optimise and standardise BRS estimation for clinical use we evaluated possible differences between spontaneous BRS indices estimated from either finger plethysmography or radial tonometry. Forty-five healthy volunteers underwen...
Background:
Depression has been associated with impaired nitric oxide (NO)-mediated vasodilation and vascular dysregulation (VD). Whether depression and NO levels will disturb retinal hemodynamics is not clear.
Objectives and methods:
Associations between the retinal vasculature, diastolic ocular perfusion pressure (DOPP) as measure of hypoperfu...
A hypercoagulable state might be one important mechanism linking obstructive sleep apnea (OSA) with incident myocardial infarction and stroke. However, previous studies on prothrombotic factors in OSA are not uniform and cross-sectional. We longitudinally studied prothrombotic factors in relation to OSA risk, adjusting for baseline levels of prothr...
The purpose of this study was to evaluate two alternative non-invasive techniques for assessment of endothelial function in adults with special focus on their ability to monitor acute changes.
Twenty-five clinically healthy men (mean age 24 ± 2 years) underwent endothelial function measurements twice in fasting state and twice after experimental in...
Objective: Autonomic system dysfunction is associated with various changes in the retinal vasculature. Depression has recently been acknowledged as a risk factor for poor prognosis in patients with acute coronary syndrome and was associated with cardiac remodelling in Black Africans. In this study we investigated the possible association between de...
Objective: Depression is associated with risk of hypertension and acute coronary syndromes. High blood pressure exerts sheer stress on vessel walls and may impair carotid and retinal perfusion, contributing to early structural wall changes. We therefore aimed to assess the association between depressive symptoms, reduced perfusion pressure and remo...
This study evaluated the responses of the retinal and cutaneous microcirculation to acute hyperlipidemia and hyperhomocysteinemia.
Twenty-five clinically healthy men (mean age 24 ± 2 years) were studied four times in a randomized order, with intervals of at least one week between the two dietary interventions always preceded by a day for baseline a...
Elevated circulating lipids and homocysteine may affect autonomic cardiovascular function by decreasing baroreflex sensitivity (BRS) and cardiovagal outflow and by increasing sympathetic drive.
To test this hypothesis 25 clinically healthy men (mean age 24 ± 2 years) received 500 ml whipping cream (30% fat) and 0.1 g/kg l-methionine, respectively,...
Insulin may link metabolic disorders to retinal microvascular pathology. The aim of the present study was to investigate the impact of early insulin resistance on retinal microcirculation.
Retinal diameter responses to flicker-light stimulation were investigated in 81 clinically healthy participants (32 ± 6 years [mean ± SD], 59% women) who were re...
A defensive pathway disturbed vascular function showing dissociation between behavioural and physiological beta adrenergic active coping responses in Africans. Vascular responses facilitated silent ischaemic events and structural LVH changes which potentially the increased risk for incident ischaemic stroke in black Africans.
Recent work identified a high prevalence of modifiable risk factors for cardiovascular disease (CVD) among urban black South Africans. The aim was to track the progression of CVD risk factors in a multi-ethnic sample of South Africans. Participants were 173 black (aged 47.5 ± 7.8 yrs) and 186 white teachers (aged 49.6 ± 9.9 yrs) that were examined...
Higher plasma concentrations of catecholamines in winter than in summer have been established, but whether this impacts the plasma concentrations of metanephrines used for the diagnosis of pheochromocytoma is unknown.
In this study, we examined seasonal variations in the plasma concentrations of metanephrines, the impact of this on diagnostic test...
Background: Higher concentrations of plasma catecholamines in winter than summer are established, but whether this impacts plasma concentrations of metanephrines used for diagnosis of pheochromocytoma is unknown.
Objective: We examined seasonal variations in plasma concentrations of metanephrines, the impact of this on diagnostic test performance...
Chronically elevated blood pressure has been associated with impaired NO-mediated vasodilation and structural vascular disease risk. This study aimed to determine whether significant associations exist regarding NO metabolite (NOx) responses, cardiovascular function and structural vascular disease in a cohort of African and Caucasian men. The study...
Bis zu ihrer klinischen Definition im Jahre 2005 fand die Stress-Kardiomyopathie aufgrund der schwierigen diagnostischen Abgrenzung zum ST-Hebungsinfarkt wenig Beachtung. Obwohl seitdem die Anzahl der Publikationen rasant gestiegen ist, wird die Ätiologie dieser reversiblen Herzerkrankung weiterhin kontrovers diskutiert. Verschiedene Hypothesen wur...
Objective
This study investigated the impact of stress on effectors of the L-arginine/nitric oxide (NO) system including the endogenous inhibitor asymmetric dimethylarginine (ADMA).Methods
Black (n = 168) and white (n = 206) South African teachers were exposed to a mental and a physical stressor for 1 minute, respectively. Serum samples for determi...
Biological rhythms, describing the temporal variation of biological processes, are a characteristic feature of complex systems. The analysis of biological rhythms can provide important insights into the pathophysiology of different diseases, especially, in cardiovascular medicine. In the field of the autonomic nervous system, heart rate variability...
To assess acute effects of bevacizumab (anti-VEGF therapy) on cerebral microvessels and systemic cardiovascular regulation.
Design and subjects
20 consecutive patients with colorectal cancer (median age: 60.4 years, range 45.5-73.9 years) received bevacizumab intravenously (5 mg/kg) uncoupled of chemotherapy. Prior to and within the first 24 hours...
Hypercholesterolemia is an important risk factor of cardiovascular diseases. Lipoprotein apheresis is an efficient strategy to reduce the serum low-density lipoprotein (LDL)-cholesterol and lipoprotein(a) levels and cardiovascular complications in patients with severe hypercholesterolemia. The underlying molecular mechanisms are not well-understood...
To determine whether previously demonstrated beneficial short-term effects on cardiovascular function in regular users of lipoprotein apheresis would be sustainable over time.
Regular users of lipoprotein apheresis (n = 17) were studied between February 2009 and July 2010. All patients were examined for endothelial and autonomic function at baselin...
The study of small-molecule metabolites may assist in cardiovascular risk monitoring during therapy. We assessed whether acute changes in the metabolome by lipoprotein apheresis are able to predict changes in microvascular function.
We performed mass-spectrometry-based profiling of 186 metabolites in peripheral plasma of 21 hyperlipidemic patients...
Background:
Research demonstrated a significant relationship between elevated nocturnal blood pressure and sympathetic hyperactivity. The study aimed to investigate possible associations between norepinephrine metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG), nocturnal BP and carotid intima-media thickness (CIMT) in urban African and Caucasian m...
Objectives:
Defensive coping (AC) responses in urban African males have been associated with vascular responsiveness, partly explaining autonomic nervous system dysfunction. We therefore aimed to assess whether AC responses facilitate higher blood pressure and early sub-clinical structural vascular disease via alterations in frequency- and time-do...
Background:
Dissociation between behavioural defensive active coping (AC) control albeit physiological "loss of control" responses was associated with silent ischaemia and structural wall abnormalities in African men. Whether it applies to structural alterations and endothelial dysfunction is uncertain. We therefore aimed to determine AC ethnic-ge...
Objective:
To evaluate the role of pain perception and pain stimulus components for blood pressure responses to stress in the black and the white African population with hypertension.
Basic methods:
Cardiovascular regulation in response to a cold pressor stimulus was studied in hypertensive black (n = 110) and white (n = 95) Africans. Perception...
Background and Objectives: Defensive active coping (AC) responses have been associated with disturbed vascular function but whether it applies to early structural vascular changes, is uncertain. We therefore aimed to determine receiver operating characteristic (ROC) carotid intima media far wall (CIMTf) cut offs best associated with risk markers na...
Objectives: To evaluate the role of pain perception and pain stimulus components for blood pressure responses to stress in the Black and Caucasian African population with hypertension. Design and Methods: Cardiovascular regulation in response to a cold pressor stimulus was studied in hypertensive Black (n = 110) and Caucasian (n = 95) Africans. Per...
Dissociation between b-adrenergic behavioral and physiological defensive active coping (AC) responses was associated with cardiometabolic risk in urban but not rural African males. Whether this is partly driven by underlying neuroendo-crine dysfunction is not certain. We aimed to assess the association between coping style, urbanization, and neuroe...
Defensive active coping responses (being-in-control, acceptance of the stressor as reality) have been associated with vascular hyper-responsiveness in urban Africans. However, the association between active coping responses, blood pressure (BP), and ECG-derived left-ventricular hypertrophy (LVH) responses is unknown.
Associations between BP, silent...
Underlying mechanisms of increased pressor responses to stress in Blacks are poorly understood. Cardiovascular regulation of normotensive Black (n=43) and Caucasian (n=90) Africans was studied during a cold pressor and color-word conflict test. Autonomic evaluation was performed by spectral analysis. Higher diastolic pressor and heart rate response...
In Africans, arterial stiffness progression seems more pronounced compared to Caucasians. We compared the arterial stiffness profiles of different age groups and focused on muscular arteries and two more central arterial segments in African and Caucasian people from South Africa. In African (N = 374) and Caucasian (N = 376) participants (20-70 year...
AIM. Research has shown a significant relationship between hypertension and attenuated baroreceptor sensitivity (BRS), which in turn reflects alterations of autonomic control of the cardiovascular system. The objective of this study was to compare the BRS of African and Caucasian men and determine possible associations with blood pressure and left...
Differences in spontaneous and drug-induced baroreflex sensitivity (BRS) have been attributed to its different operating ranges. The current study attempted to compare BRS estimates during cardiovascular steady-state and pharmacologically stimulation using an innovative algorithm for dynamic determination of baroreflex gain.
Forty-five volunteers u...
Evidence from family, twin, and adoption studies indicates that there is a significant genetic contribution to major depressive disorder. However, the majority of individuals with a positive family history of depression do not develop depression. Thus, current hypotheses about the role of genes for the development of depression collectively favor t...
Hypotensive episodes are relatively frequent adverse effects during LDL apheresis. To evaluate the impact of LDL apheresis on autonomic cardiovascular control we investigated hypercholesterolemic patients before and after a single LDL apheresis in comparison to an age-matched control group.
We continuously recorded systemic arterial blood pressure,...
Carotid endarterectomy (CEA) is the first-line treatment in severe carotid stenosis to prevent stroke. Because of methodological limitations, the acute impact of CEA on baroreflex function and cerebral autoregulation is not well defined and was therefore investigated by applying a novel algorithm.
Systemic arterial blood pressure, ECG and respirati...
The assessment of baroreflex sensitivity (BRS) has emerged as prognostic tool in cardiology. Although available computer-assisted methods, measuring spontaneous fluctuations of heart rate and blood pressure in the time and frequency domain are easily applicable, they do not allow for quantification of BRS during cardiovascular adaption processes. T...
3575 Background: The VEGF antibody bevacizumab has been shown to increase efficacy of palliative treatment in several malignancies. Validated biomarkers are still warranted. Inhibition of VEGF-mediated release of NO by bevacizumab has been shown in vitro. By dynamic retinal vessel analysis, we wanted to address the flicker light-induced arterial va...
The cold hand sign (CHS) is a distinct feature of multiple system atrophy (MSA), but its pathophysiology is poorly understood. We, therefore, conducted a study to examine the skin temperature and the skin blood flow at rest and after local heating in 6 age-matched MSA patients with CHS (MSA + CHS), 18 MSA patients without CHS (MSA - CHS) and 13 pat...
Changes in the microcirculation per se may precede macrovascular changes, hence, may present a good surrogate for monitoring vascular changes during treatment. Using retinal vascular imaging techniques, we attempted to investigate the microvascular benefit of a single LDL apheresis in hypercholesterolemia.
Twenty-one hypercholesterolemic patients (...
To test the hypotheses that sleep deprivation in neurology residents is associated with performance deficits and that vigilance and cognitive performance is more compromised after overnight on-call duty compared to night shift.
Thirty-eight neurology residents of a university teaching hospital participated in a prospective single-blind comparison s...
Differential diagnosis of parkinsonian syndromes is a major challenge in movement disorders. Dysautonomia is a common feature but may vary in clinical severity and onset. The study attempted to find a pattern of autonomic abnormalities discriminative for patients with different parkinsonian syndromes. The cross-sectional study included 38 patients...
Sub-Saharan Africa is afflicted by high hypertension prevalence that is expected to rise even further along with increasing obesity rates. The present study aimed to investigate the role of visfatin in obesity and to explore associations of visfatin with markers of endothelial function and hemodynamics in African women compared to a well-matched wh...
Type 1A (immune-mediated) and type 2 diabetes mellitus are two of the most common severe chronic illnesses, affecting over 230 million people worldwide with an estimated global prevalence of 5.1%. Although type 1 and type 2 diabetes differ greatly in modes of pathogenesis, these illnesses share a common pathology and consequences characterized by l...
The Finnish Diabetes Risk Score (FINDRISC) questionnaire is a practical screening tool to estimate the diabetes risk and the probability of asymptomatic type 2 diabetes. In this study we evaluated the usefulness of the FINDRISC to predict insulin resistance in a population at increased diabetes risk.
Data of 771 and 526 participants in a cross-sect...
The aim of the present study was to evaluate the performance of the Finnish diabetes risk score (FINDRISC) for identifying undiagnosed type 2 diabetes in a German population and to develop a more simplified alternative model. We invited 921 individuals with a family history of the metabolic syndrome in a cross-sectional survey. Of these, 771 subjec...
The increasing prevalence of hypertension and vascular-related morbidity and mortality among Africans emphasizes the need to identify markers for the early detection of vascular disease. Caucasian-based studies demonstrate that the von Willebrand factor (vWf) is a useful marker of vascular dysfunction. We investigated whether associations between t...
The high prevalence of human immunodeficiency virus infection and the emergence of HIV-related metabolic syndrome from its successful treatment in African countries are discussed. The classical factors fuelling metabolic syndrome as well as the role of urbanization are considered in this review. The future impact of ongoing conflicts and famine in...
Mutations in the hepatic nuclear factor-1-alpha ( HNF-1alpha) gene is considered as a candidate for the aetiology of type 2 diabetes. The aims of the study was to determine whether two single nucleotide polymorphisms (SNPs) ile27-to-leu and ala98-to-val in the HNF-1alpha gene associate with diabetes, insulin sensitivity as well as beta-cell functio...
Perilipins are hormonally regulated phosphorylated proteins that coat the intracellular lipid storage droplet . They are essential for the regulation of triglyceride deposition and mobilization . The human perilipin gene (PLIN) is located to 15q26.1, near the susceptibility loci for obesity, and insulin-dependent diabetes mellitus, and hypertriglyc...
Peripheral arterial disease is more aggressive in concomitant diabetes posing an increased risk for critical limb ischemia and subsequent limb loss. The majority of therapies available are not effective to prevent amputation in patients with severe disease. The current observational study reports the effect of the heparin-induced extracorporal LDL-...
Hypertension is highly prevalent in South Africa, resulting in high stroke mortality rates. Since obesity is very common among South African women, it is likely that obesity contributes to the hypertension prevalence. The aims were to determine whether black African women have higher blood pressures (BPs) than Caucasian women, and whether obesity i...
To assess the risk factor pattern of the metabolic syndrome and its association with insulin resistance and hyperuricaemia in a sub-Saharan African population with different levels of urbanisation.
Four hundred forty-eight black South African volunteers, men and women aged 15 years and older were investigated in a cross-sectional, comparative, popu...
Transcription factor Neurogenin 3 (NGN3) is considered as a candidate gene for the development of type 2 diabetes. The aim of the current study was to investigate the relevance of NGN3 variants for the clinical spectrum of diabetes development and disease progressions.
A total of 552 subjects with increased risk of type 2 diabetes were investigated...
Objective: The Finnish Diabetes Risk Score (FINDRISC) questionnaire is a practical screening tool to estimate the risk of type 2 diabetes and the probability of asymptomatic type 2 diabetes. In this study we evaluated the usefulness of the FINDRISC as preventive screening tool by analyzing the FINDRISC and insulin resistance relationship as well as...
The risk for insulin resistance and subsequent type 2 diabetes varies between different ethnic populations due to differences in the genetic and environmental background. However, obesity and unhealthy lifestyle, crucial determinants of insulin resistance, are on the rise throughout all population groups though the susceptibility towards those fact...
Germany developed today into a country of immigration, which creates an additional burden for the social security system and results in a new challenge for the healthcare. In the last 17 years more than two million "Russia Germans" have been repatriated and about two hundred thousand Jewish refugees have resettled in Germany from the former Soviet...
In the last years we have learned a lot about the pathopysiology of a cluster of the diseases called Metabolic Syndrome but currently an exciting discussion debates the Metabolic Syndrome in a light of a mystery of medicine or a clinical paradigm with a controversary about diagnostic, treatment or preventive procedure. There is now convincing evide...
Ethnic differences in obesity and obesity related disorders prompted us to search for possible contributors. The impact of the novel cardiovascular risk factor asymmetric dimethylarginine (ADMA) has been never determined in the African population. The present observational study aimed to compare ADMA levels between healthy African (102) and Caucasi...
The influence of obesity indices and adipokines on aortic input impedance (Z(c)) was determined in 102 African and 115 Caucasian women from South Africa aged 20-55 years after stratification into lean, overweight and obese groups. Zc decreased significantly with increasing weight in both populations, but overweight and obese African women exhibited...
The present study aimed to reveal racial differences in the metabolic pattern of C-peptide and non-esterified fatty acids (NEFA), and in their associations with cardiovascular measures in healthy urban African (102) and Caucasian women (115) from South Africa. An oral glucose tolerance test was performed with measurements before and at 30, 60, 90 a...
Soya isoflavones are thought to be cardioprotective due to their structural similarity to oestrogen. In order to investigate the effect of soya isoflavones on markers of endothelial function we conducted a randomised, double-blind, placebo-controlled, cross-over study with thirty healthy postmenopausal women. The women consumed cereal bars, with or...
Homocysteine and asymmetric dimethylarginine (ADMA) affect nitric oxide (NO) concentration, thereby contributing to cardiovascular disease (CVD). Both amino acids can be reduced in vivo by estrogen. Variation in the estrogen receptor (ER) may influence homocysteine and ADMA, yet no information is available on associations with single nucleotide pol...
The hypocholesterolemic effects of soy foods are well established, and it has been suggested that isoflavones are responsible for this effect. However, beneficial effects of isolated isoflavones on lipid biomarkers of cardiovascular disease risk have not yet been shown.
The objective was to investigate the effects of isolated soy isoflavones on met...
Soy isoflavones show structural and functional similarities to estradiol. Available data indicate that estradiol and estradiol-like components may interact with gut "satiety hormones" such as peptide YY (PYY) and ghrelin, and thus influence body weight. In a randomized, double-blind, placebo-controlled, cross-over trial with 34 healthy postmenopaus...
Postmenopausal women are at increased risk for cardiovascular disease because many risk factors are aggravated by menopause. Phytoestrogens may modulate risk factors favorably, involving mechanisms similar to estrogen. The effect of phytoestrogens on the atherogenic amino acids homocysteine and asymmetric dimethylarginine (ADMA) was investigated in...
Homocystein (tHcy) gilt als unabhängiger kardiovaskulärer Risikofaktor und korreliert eng mit einer endothelialen Dysfunktion, welche nichtinvasiv mittels der flussinduzierten Vasodilatation (FMD) messbar ist. Experimentelle Hyperhomocysteinämie ist mit einer reduzierten Bioverfügbarkeit von endothelialen Stickstoffmonoxid (NO) bei gleichzeitig erh...
Dietary isoflavones are thought to be cardioprotective because of their structural similarity to estrogen. The reduction of concentrations of circulating inflammatory markers by estrogen may be one of the mechanisms by which premenopausal women are protected against cardiovascular disease.
Our aim was to investigate the effects of isolated soy isof...