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Biomedical subjects

W Vetter

Publications and source records attributed to W Vetter.

At least 19 recordsLinked to original sources
PubMed1997

Enantioselective determination of chiral organochlorine compounds in biota by gas chromatography on modified cyclodextrins.

Approaches to the gas chromatographic enantiomer separation of chiral organchlorines (alpha-hexachlorocyclohexane, cis- and trans-chlordane, heptachlor, heptachlorepoxide, oxychlordane, o,p'-DDT, compounds of technical toxaphene and stable atropisomeric polychlorinated biphenyls) are reviewed. Chiral stationary phases based on cyclodextrin derivatives and used for the gas chromatographic enantiomer separation of the chiral organochlorines are described. Enantiomeric ratios of chiral organochlorines in technical mixtures and biological samples are reported and discussed.

Animals↗
PubMed1997

[The effect of short-term hyperventilation on the concentration of ionized serum calcium].

BACKGROUND AND OBJECTIVE: Paraesthesias and carpopedal spasms on hyperventilation are explained by a reduction in ionised serum calcium (ISC). We tested whether 5-minute hyperventilation changes the concentration of ISC. SUBJECTS AND METHOD: Arterial blood samples were obtained via a small plastic catheter introduced into the femoral artery of ten healthy male volunteers (mean age 33 years) before, during and after 5 minutes of hyperventilation, which was achieved by deep and rapid breathing and considered adequate when the end-expiratory pCO2 had fallen to 2.5 kPA within the first minute and remained below this level during the remaining 4 minutes. These criteria were met in nine of the ten patients. The ISC concentration was measured with an ion-selective electrode, the pH, paCO2 and bicarbonate levels with an autoanalyser. RESULTS: Paraesthesias of the fingers and hand occurred in nine of the volunteers, carpopedal spasms in seven. Despite a definite rise in pH from 7.39 +/- 0.02 to 7.75 +/- 0.045, the concentration of ISC did not change significantly during the hyperventilation. CONCLUSION: Paraesthesias and carpopedal spasms which occur during hyperventilation are not caused by a fall in ionised serum calcium in arterial blood.

Adult↗
PubMed1997

[Significance of diuretics in the treatment of hypertension].

Due to new therapeutic substances the use of diuretics in the treatment of hypertension is decreasing slowly over the last few years. Nevertheless diuretics still represent one important cornerstone in the therapy of most forms of high blood pressure. Metabolic side effects of diuretics are often used as an argument against their clinical use. Indeed the diuretic therapy may lead as a function of the dosage and the duration of the therapy to an increase of total cholesterol and an impairment of the glucose tolerance. Spironolactone and other potassium sparing diuretics are "lipid-neutral". These metabolic side effects of the diuretics can be counterbalanced by the implementation of non-pharmacological means of blood pressure therapy. Body weight control seems to be of central importance. Therapy resistant forms of hypertension may be caused by many different pathogenetic mechanisms. Besides other reasons (such as secondary hypertension, non compliance ect) volume overload may represent one of the most important reasons of resistant forms of hypertension. Diuretics, especially also the aldosterone antagonists, play a central role in the control of most situations associated with volume overload in the setting of essential hypertension.

Antihypertensive Agents↗
PubMed1997

Relationship between self-perceived stress and blood pressure.

OBJECTIVE: The importance of stress in the pathogenesis of essential hypertension is controversial. In this study we wanted to evaluate the relation between self-perceived stress and the blood pressure (BP) in a asymptomatic healthy population. SUBJECTS AND METHODS: A total of 1666 guests (mean +/- s.d. age 50 +/- 16 years) attending the air show AIR94 in Buochs, Switzerland volunteered to participate in a cross-sectional study. Using a self-administered questionnaire and visual analogue scales the individual stress perception and other cardiovascular risk behaviours/factors were assessed. BP, body weight, height, and the waist:hip ratio were measured. RESULTS: Individual stress perception was inversely related with the systolic BP (SBP) (r = -0.12, P < 0.001). The relationship was found in both men and women and was independent of age and/or body weight. No relation was found between the diastolic BP (DBP) and stress perception. Subjects with high normal BP according the JNC V classification showed a lower stress perception than did subjects with normal BP. In a multiple regression model the stress score was fourth most predictive of the SBP after body mass index, waist:hip ratio, and age followed by alcohol and fat intake. CONCLUSION: In this study we found an inverse association between the self-perceived stress and SBP. We suggest that the inverse association between BP and the self-perceived stress reflects a neuroendocrine and biochemical setting characterized by inadequate stress handling associated with a higher fat and alcohol intake and more abdominal fat tissue leading to a higher BP. Our data suggest that stress denial in combination with abdominal obesity, alcohol consumption, and smoking may be proxy for a high stress level.

Adult↗
PubMed1997

Low-density lipoprotein-induced formation of nitric oxide by cultured vascular smooth muscle cells of the rat.

There is evidence that low-density lipoprotein (LDL) plays a crucial role in atherogenesis. On the cellular level, LDL has been shown to activate a number of mechanisms involved in atherogenesis and vasoconstriction. Local immoderate vasoconstriction is physiologically antagonized by nitric oxide, which is released from the endothelium. To find out whether LDL also influences the synthesis of nitric oxide in vascular smooth muscle cells, both the conversion of arginine to citrulline and the production of nitrite were determined as a measure of nitric oxide formation. After incubation of rat vascular smooth muscle cells with native LDL (25 micrograms mL-1) for 24 h, the production of both L-[14C]-citrulline [39600 (3600) cpm mg-1 cell protein] and nitric oxide [2.95 (0.56) mumol L-1] were about twice and 1.5-fold the amount of the corresponding values in untreated cells (mean +/- SD, P < 0.05, n = 4). Oxidized LDL was less effective than the native form. The presence of the arginine analogue NG-methyl-L-arginine reduced citrulline production dose-dependently but augmented DNA synthesis, both induced by LDL. In addition, the lipoprotein caused a 1.6-fold increase in cyclic GMP production following a 24-h incubation [control = 10.9 (3.8) pmol mg-1 cell protein, P = 0.016]. The results suggest that native LDL might partly impair its atherogenic potential on the vasculature by stimulating the production by smooth muscle cells of both nitric oxide and cyclic GMP.

Animals↗
PubMed1997

Effects of alcohol on energy metabolism and body weight regulation: is alcohol a risk factor for obesity?

Some studies have suggested that drinking in moderation may be beneficial for health, but many of these studies do not address body weight. Evidence suggests that consuming moderate amounts of alcohol is a risk factor for obesity, which is a risk factor for several adverse health outcomes. Recommendations regarding alcohol intake thus should take into account a variety of factors, including baseline body weight, location of body fat, and overall diet.

Alcoholic Beverages↗
PubMed1997

Changes in arterial and transcutaneous oxygen and carbon dioxide tensions during and after voluntary hyperventilation.

The purposes of our study were (1) to investigate whether a 3-min short-term hyperventilation leads to posthyperventilatory hypoxemia and (2) to assess the role of transcutaneous blood gas measurements for monitoring oxygen and carbon dioxide changes during the after the test. In 10 male volunteers arterial and transcutaneous blood gases were measured simultaneously before, during and after a 3-min voluntary hyperventilation maneuver. Baseline arterial PO2 increased from 13.7 +/- 0.4 kPa (103 +/- 3 mm Hg) to 18.6 +/- 0.3 kPa (139 +/- 2.3 mm Hg; p < 0.005 compared to baseline) during hyperventilation. After the provocation test posthyperventilatory hypoxemia occurred with a minimal mean value of 7.8 +/- 1.3 kPa (58.5 +/- 9.8 mm Hg; p < 0.05 compared to baseline). Whereas close agreement between arterial and transcutaneous measurements was obtained for carbon dioxide values before hyperventilation, transcutaneous O2 consistently underestimated arterial O2. A short-term over-breathing of 3 min causes a significant posthyperventilatory hypoxemia. We hypothesize that posthyperventilatory hypoxemia is caused by hypopnea as a result of depleted CO2 body stores. Noninvasive transcutaneous blood gas measurements are not reliable for monitoring blood gas changes during and after hyperventilation, most probably because of the slow response time of the electrodes and the reflex vasoconstriction of the skin vessels.

Adult↗
PubMed1996

[Analysis of various continuing medical education courses].

Two types of postgraduate medical education were analyzed by questionnaires: 'afternoons for practitioners' taking place at the university clinics in Zurich and 'seminars in internal medicine' held for 2 1/2 days in the seminar facilities of a pharmaceutical firm in Freiburg (Germany). For both cases, the demand for and the interest in the event was confirmed. Overall, those presentations were favoured which offered more time for an interaction with the speaker. Since the interest of the participants focussed on practical aspects, those presentations received better marks that addressed medical practice directly. Furthermore, teaching methods encouraging active collaboration by the participants were favoured. Speakers at the 'seminars in internal medicine' were informed about acceptance of their performance, thus leading to an improvement of subsequent seminars. Our findings encourage to analyze in depth continuing postgraduate education events in the future. The feedback of the assessment by participants to the speakers leads to significant improvements.

Consumer Behavior↗
PubMed1996

[Fever and headache].

A 30-year-old male patient was admitted to our outpatient clinic because of fever, headache and cerebellar symptoms. Clinically he presented with a slight meningism. After exclusion of a focal intracerebral process by head scanning, a first diagnosis of an aseptic meningitis was made by the analysis of the cerebrospinal fluid. With the hint of repeated tick bites, the diagnosis of an early-summer meningoencephalitis was confirmed. The patient recovered without neurological residua within two months. The clinical course, dates of new epidemiologic studies and problems of vaccination are discussed.

Adult↗
PubMed1996

[Detection of RET-proto-oncogene mutations in the diagnosis of Type 2 endocrine neoplasia (MEN 2)].

We have analyzed 95 blood- and 25 paraffin-derived DNA samples of 120 individuals from Switzerland (MEN 2 family members and patients with medullary thyroid carcinoma or pheochromocytoma) for the presence of RET protooncogene mutations in exons 10, 11, 13, 14 and 16, where recently germline point mutations have been identified in more than 95% of patients with MEN 2A, familial medullary thyroid carcinoma (FMTC) and MEN 2B. Molecular DNA screening of samples was performed by non-radioactive single strand conformation polymorphism (SSCP) and heteroduplex gel electrophoresis method followed by mutation analysis of PCR products by direct cycle sequencing using an automated DNA sequencer. We identified 12 MEN 2A/FMSC and 6 MEN 2B families with 29 gene carriers. Ten different types of mutations were identified in the MEN 2A/FMTC families (620 Cys-->Arg, 618 Cys-->Ser, Gly, 611 Cys-->Tyr; 634 Cys-->Arg, Tyr, Trp, Phe, Ser, Gly) and all 6 MEN 2B families had a 918 Met-->Thr point mutation. Our results indicate that PCR-based DNA testing for RET point mutations is a rapid, accurate and reproducible method of identifying MEN 2 gene carriers using blood or tissue DNA. Early detection of gene carriers allows preventive thyroidectomy without neck dissection or parathyroid transplantation, and non-gene carriers can be released from biochemical testing. Furthermore, it is shown that the distribution and localization of RET mutations in MEN 2 families from Switzerland concur with combined results of larger series and that a "founder effect" of MEN 2 can be excluded for this country.

Adrenal Gland Neoplasms↗
PubMed1996

Organochlorine residues in marine mammals from the northern hemisphere--a consideration of the composition of organochlorine residues in the blubber of marine mammals.

Levels of organochlorines (PCBs, sigma DDT, lindane and its isomers, HCB, chlordane, and toxaphene) were determined in blubber of marine mammals from the northern hemisphere. Differences in both levels and ratios of organochlorine compounds were detected in different species of marine mammals living in the same region, e.g. blubber of harbour seals (Phoca vitulina) accumulated significantly lower levels of lindane, HCB, toxaphene, and DDT and its metabolites than harbour porpoises (Phocoena phocoena). Compared to such elementary differences in the organochlorine pattern in different marine mammals, the influence of age and sex on the results was only minimal. Varying ratios of contaminants in individual harbour porpoises were explained by migration. Constant PCB/DDT ratios were measured in harbour seals. Due to the sedentariness of harbour seals, even local sources of contaminants could be recognized. Careful evaluation of the organochlorine levels and ratios in marine mammals made it possible to monitor the transport of PCBs from the European continent to European Arctic regions.

Adipose Tissue↗
PubMed1996

[Hypertension and coronary heart disease. Global risk moderation through control of body weight].

The moderation control of blood pressure is one key strategy to control the progression of coronary artery disease. In the pathogenesis of coronary artery disease, hypertension should not be viewed on its own; however, other risk factors, which may influence hypertension and atherogenesis at the same time, should be evaluated carefully. In primary and also secondary prevention of coronary artery disease, overweight and obesity play an important modulating role. Especially the abdominal (visceral) form of obesity should be controlled. The reduction of dietary fat intake seems to be the major strategy to control body fat accumulation and weight gain, since the intake of excess fat does not lead to an increased oxidation of fat. The reduction of fat intake is also the major nonpharmacological strategy to promote regression of atherosclerosis and to control body weight.

Body Weight↗
PubMed1996

24-hour blood pressure monitoring in patients with anterior ischemic optic neuropathy.

OBJECTIVE: To define parameters of ambulatory diurnal blood pressure in patients who had experienced anterior ischemic optic neuropathy (AION) in a case-controlled study. PARTICIPANTS AND METHODS: Twenty-four patients with AION and 24 control subjects who were matched for age, gender, medical diagnoses, and medications underwent ambulatory automated blood pressure monitoring for 24 hours. RESULTS: The overall diurnal pattern of blood pressure appeared to be normal in all subjects, showing lower blood pressures at night than during the day, an overnight nadir, and an ascending blood pressure curve in the morning to reach daytime levels. Also, patients with AION did not differ from control subjects with respect to the nighttime diastolic nadir or daytime peak systolic blood pressure. However, during the daytime, patients with AION had lower mean systolic and diastolic blood pressures than did matched control subjects. The widest difference between their blood pressure curves occurred after awakening in the morning, when patients with AION had a less steep and more irregular rise of blood pressure. Patients who had signs of vertebrobasilar insufficiency in addition to AION had lower mean diastolic blood pressure during both daytime and nighttime and a lower minimum daytime diastolic blood pressure. CONCLUSIONS: On ambulatory measurements of diurnal blood pressure, patients with AION consistently had a lower mean blood pressure than did control subjects and a lag in the usual rise in blood pressure in the morning to meet increasing daytime demands for perfusion. Chronic hypoperfusion of small end-arterial vessels that supply the optic nerve head may predispose to AION, and may be caused by relative hypotension owing to overtreated hypertension or to abnormal vascular autoregulation. Internists should be asked to monitor blood pressure carefully when treating hypertensive patients who are at risk for AION, to avoid hypotension, especially on awakening in the morning.

Aged↗
PubMed1995

[Circadian profile of blood pressure and heart rate in geriatric patients with and without dementia].

In this report, investigations on circadian blood pressure fluctuations in geriatric patients with or without senile dementia are reported. 24 patients of a nursing home in Zurich have been included in the study. In senile patients without dementia, persistence of circadian blood pressure rhythm, including a nocturnal decrease of blood pressure, could be demonstrated. In very old patients, however, reduced day-night amplitudes or loss of day-night rhythm, respectively, were observed. In the group of demented patients and in a subgroup including only patients with Alzheimer's disease, loss of circadian blood pressure rhythm and a lacking drop of nocturnal blood pressure values were found, while diurnal rhythmicity of the heart rate remained unchanged. Furthermore, our results demonstrate that there was no circadian blood pressure rhythm detectable in the five patients with Parkinson's syndrome (with or without dementia). The results of this study suggest that degenerative processes of the central nervous system interfere with circadian blood pressure rhythm.

Age Factors↗
PubMed1995

[Hypertension in the elderly: definition, indications for treatment and clarification].

Hypertension is the single most potent common and remediable risk factor for cardiovascular morbidity and mortality in the population over age 65. Data from newer intervention studies show that it is clearly beneficial to treat elderly patients with either both systolic and diastolic hypertension or with isolated systolic hypertension. The indication to start treatment in a given patient depends on blood pressure values, age and eventual concomitant disease. In the evaluation of the elderly hypertensive patient, multiple blood pressure measurements in the standing and lying patient should be taken. In the case of suspected carotid artery stenosis, a Doppler ultrasound is indicated before starting antihypertensive therapy. Finally, if refractory hypertension or kidney failure develop in an elderly patient, renal artery stenosis should be considered.

Aged↗
PubMed1995

[Treatment of hypertension in elderly patients].

Today indications for treatment of hypertension in older age are no longer contested, even if only systolic pressure is raised. The choice of the antihypertensive drug for elderly patients, however, depends on concomitant diseases. The diversity of the latter demands a judicious, individualized use of the available substances (diuretics, beta-blockers, calcium antagonists and ACE-inhibitors). In elderly patients as well, a marked reduction of the cardiovascular risk is achievable by pharmacotherapy. So far, however, such results have only been reported for the use of diuretics and beta-blockers, in purely systolic hypertension by diuretics exclusively; however smaller studies, suggest that comparably favorable results may be obtained with calcium antagonists.

Adrenergic Antagonists↗
PubMed1995

Organochlorine residues in two seal species from western Iceland.

Harbour seals and grey seals from Faxaflói (Western Iceland) were analyzed for contamination with organochlorines (HCB, PCBs, p,p'-DDT,p,p'-DDE, chlordanes and the enantiomers of alpha-HCH). Although the values strongly varied, both harbour seals and grey seals on averaged showed comparable levels of PCBs, p,p'-DDT, p,p'-DDE and alpha-HCH, as well as chlordanes (sigma CD). Differences were measured in the HCB content of the seal species. The HCB/alpha-HCH ratio in harbour seals was < 1 and in grey seals > 1. The results from seals on Iceland were compared with data derived from seal samples of the Antarctic, the Arctic (Spitzbergen) and the North Sea (Germany) in order to give an insight into the global distribution of pollution with chlorinated organics.

Animals↗