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Biomedical subjects

J Mayer

Publications and source records attributed to J Mayer.

At least 217 records · Page 12Linked to original sources
PubMed1993

[Hemodynamics and sleep structure in attempted weaning after nCPAP ventilation therapy of obstructive sleep apnea syndrome].

nCPAP (continuous positive airway pressure) treatment is presently the standard therapy in marked obstructive sleep apnoea syndrome. Fundamentally, this is a long-term treatment. Various authors have been making different recommendations in respect of the frequency of application, based partly only on the patient's individual pattern of complaints and symptoms. Our study aimed at examining the short-term nocturnal effects of discontinuing the treatment course in 12 patients, using polysomnography as a diagnostic tool. Results showed that directly after discontinuation of therapy the sleep structure, respiration during sleep and the nocturnal blood pressure pattern returned to baseline findings. It is concluded from this that nCPAP treatment should be strictly adhered to every night to minimise the risk of cardiovascular complications in the patients concerned.

Adult↗
PubMed1993

[Hypertension at awakening in sleep apnea].

There is an increased mortality among patients with sleep related breathing disorders. This fact is largely ascribed to arterial hypertension and its associated cardiovascular risk with which sleep apnoea is interlinked, as is known from epidemiological and clinical studies. The present study was based on 20 males suffering from arterial hypertension and sleep apnoea, measuring the blood pressure changes 4 hours before and 4 hours after waking up, in each case without therapy and after 8 weeks' treatment with a combination preparation made up from verapamil and a potassium-saving diuretic. Besides the usual polysomnographic measurements in the sleep laboratory blood pressure was measured intra-arterially and continually, each time on two consecutive days. The average age was 53 (39-70) years, and the average of Broca's index was 129 (109-158). It was found that blood pressure values rise already 2-3 hours before waking up and maximum is attained subsequent to waking. Under therapy the minimal systolic values before waking dropped from 132.8 mmHg (+/- 22.8) to 119.4 mmHg (+/- 11.9) (p < 0.01) and the maximal values after awakening were reduced with 149.8 mmHg (+/- 27.7) vs 132.7 mmHg (+/- 25.4) (p < 0.01) without dropping to hypotensive levels. Under therapy there was a less marked and also slower rise in blood pressure with time. Besides pointing to the fact that endogenous mechanisms also influence blood pressure patterns in addition to the well-known exogenous influences, the study proved the favourable therapeutic action of treatment with an antihypertensive drug that is effective for a period of 24 hours.

Adult↗
PubMed1992

Significance and quantitative analysis of von Willebrand factor in human platelets.

The von Willebrand factor (vWF) is found in plasma and in platelets. The concentration and multimeric composition of the vWF in platelets of 160 patients with bleeding tendency were examined since very little is known about the platelet vWF. For quantitative analysis of the platelet vWF, a modified ELISA was established. A reference range from 70%-130% of platelet vWF concentration considered normal was established by examining 80 healthy blood donors. 16.9% of the 160 patients showed a decreased vWF concentration in platelets only, while all the other coagulation parameters were normal. 3 of our patients belong to the same family and suggesting an autosomal dominant genetic transmission for the von Willebrand disease type 1-3. The data also suggests, that a quantitative and qualitative analysis of the vWF in plasma and platelets is required for an exact diagnosis of the von Willebrand disease.

Blood Donors↗
PubMed1992

Effects of long-term treatment with lovastatin on the clotting system and blood platelets.

In a study of 20 patients with hypercholesterolemia (type IIa) the effects of lovastatin (20-80 mg/day) on various clotting and thrombosis parameters were monitored for 12 months. On 11 occasions various cholesterol fractions and clotting parameters were determined in each patient. In addition, the clotting inhibitors AT III, protein C, protein S, and C1-esterase inhibitor and the fibrinolysis parameters plasminogen and alpha 2-antiplasmin were examined. Platelet function was monitored on the basis of spontaneous and induced (collagen, ADP, epinephrine, ristocetin) aggregation. Lovastatin in the above dosage brought about a 66 mg/dl (from 320 +/- 12.6 to 254 +/- 12.0 mg/dl) reduction in the total cholesterol level and a 56 mg/dl (from 244 +/- 11.4 to 188 +/- 12.1 mg/dl) reduction in LDL cholesterol at the end of the study. Fibrinogen showed a significance decrease during the study period, whereas PT and aPTT remained unaffected. The initial slopes of the ADP-induced platelet aggregation revealed a significant decrease. C-reactive protein and platelet count remained within the normal range, indicating no significant change. Thrombin clotting time, AT III, C1-esterase inhibitor, plasminogen, and alpha 2-antiplasmin were not modified. Protein C and S behaved in a contradictory way, but remained within the normal range. Long-term treatment with lovastatin was associated with a significant reduction of fibrinogen levels and platelet aggregation induced by ADP in type-IIa hypercholesterolemic patients. These alterations, as well as their role in cardiovascular disease, should be the subject of further investigations.

Adolescent↗
PubMed1992

Small area analysis of surgery for low-back pain.

Rates of spine surgery (discectomy, laminectomy, fusion) vary several-fold among "small areas" such as counties or hospital market areas. To ascertain why this is so, an analysis was conducted of variability in rates among counties in the State of Washington (N = 39). Since, unlike previous published reports, this study excluded patients with cancer, major trauma, and infection, as well as those with cervical and thoracic procedures, rates in this study pertain specifically to the problem of low-back pain. Six classes of variables to explain variability among county rates were defined: I) percentage of the labor force in heavy labor and transportation occupations; II) socioeconomic conditions; III) neurologic and orthopedic surgeon density; IV) occupancy rate of back surgery hospitals; V) primary payer and VI) health care availability. In all, the effect of 28 explanatory variables was tested. In doing so, the authors took into account the possibility of spurious correlation. The rate of surgery for low-back pain varied nearly 15-fold among counties. The explanatory variables that were tested, however, accounted for only a minor part of the variability. The hypothesis that "physician practice style factor" accounts for the major part is explored; potential properties of practice style factor are specified for further testing.

Back Pain↗
PubMed1992

DNA adducts and related biomarkers in populations exposed to environmental carcinogens.

Prevention of environmentally related cancer will be enhanced by the availability of sensitive early warning systems and by improvements in quantitative assessment of human risks. Accordingly, we have carried out a series of molecular epidemiologic studies aimed at validating a panel of biologic markers, including carcinogen-DNA and -protein adducts, sister chromatid exchange, micronucleus formation, DNA strand breaks, and DNA repair capacity. Results from three such studies illustrate the usefulness of these biomarkers in elucidating low-dose-response relationships, correlations between biomarkers, and the range of variation in biomarkers between individuals exposed to similar concentrations of carcinogens. Low-level workplace or ambient exposures to styrene, ethylene oxide, and polycyclic aromatic hydrocarbons (PAH) were associated with significant increases in both molecular dose of carcinogens (adducts) and various markers of preclinical effects. Correlations between biomarkers varied by exposure. For example, in the styrene study, sister chromatid exchange frequency was not correlated with any of the markers, in contrast to the studies of ethylene oxide and PAH. Significant molecular effects were observed not only in occupationally exposed people but also in residents of an area in Poland characterized by high levels of air pollution. For example, the mean PAH-DNA level in exposed residents (winter sample) was 30.4 adducts per 10(8) nucleotides. This level was significantly higher than that of adducts seen in summer samples from the same area (4.2/10(8), or in winter samples from residents of a rural area (11.01/10(8). Significant seasonal variation in PAH-DNA adduct formation in this group was consistent with recorded fluctuations in air pollution levels. Striking interindividual variation was observed in all three exposed populations.

Biomarkers↗
PubMed1992

[Diagnostic strategies for detection of the von Willebrand syndrome].

The von Willebrand disease (vWD) is the most severe coagulopathy. Because of the complex biochemical structure of the von Willebrand factor (vWF), a great number of types and subtypes of the vWD were found. A screening of vWD can only be done by examining the bleeding time, the ristocetin cofactor activity (risto) and by an immunological determination of the vWF concentration. Examinations of 200 patients with a bleeding tendency showed that the ratio vWF/risto < 0.7 indicates a high probability for an abnormal multimeric structure of vWF. The exact determination of the vWD subtype then has to be done by a SDS-agarose gel electrophoresis. In 16.8% of our patients we found a decreased vWF concentration in the platelets. These patients showed normal plasmatic coagulation factors, but a bleeding tendency and a prolonged bleeding time. For diagnosis of vWD the bleeding time, immunological determination of the vWF and the risto should be done first. If a ratio vWF/risto < 0.7 or a prolonged bleeding time with a bleeding tendency is found, the separation of the vWF multimers into plasma and platelets and the determination of the vWF concentration in platelets should be carried out for an exact diagnosis of vWD.

Blood Coagulation Tests↗
PubMed1992

[Analysis of long-term blood pressure measurements during sleep].

Fifty patients with sleep-related breathing disorders and arterial hypertension underwent diagnostic polysomnography for two nights; EEG, EOG, EMG, and respiratory signals were recorded in parallel with invasive blood pressure. Computerized evaluation was performed to calculate systolic and diastolic blood pressure values, as well as heart rate beat-to-beat. All signals were stored once per second for further evaluation. These time series were analyzed in respect of underlying periodicities by means of spectral analysis. It was possible to distinguish four different groups of patients according to the compressed spectral arrays. Pronounced peaks of different extents were found that reflected both periodicities of respiration (3-5 s) and periodicities of sleep apnea (30-60 s). A comparison of spectral analysis of blood pressure and heart rate showed that systolic blood pressure is suited best to recognize periodicities related to respiration and apneas.

Adult↗
PubMed1992

Continuous non-invasive blood pressure monitoring in patients with sleep disorders.

Sleep related breathing disorders are of high prevalence and are often associated with essential hypertension. It is therefore necessary to study blood pressure continuously in all patients with sleep related breathing disorders and arterial hypertension as well as in all patients with essential hypertension and suspected sleep apnoea. To investigate the usefulness of a non-invasive continuous volume-clamp method during sleep we used this technique in parallel with 130 sleep recordings and performed a validation study of the Finapres instrument on a subgroup where continuous invasive blood pressure recordings were available. Absolute pressure values of Finapres are valid when the position and the movement of the sensor were carefully observed and only appropriate segments of the recordings were taken for further evaluation. The high beat to beat resolution of the systolic and diastolic pressure is the main advantage of this non-invasive technique because it reflects rapid blood pressure variations as they occur in sleep related breathing disorders. This could be investigated only invasively until now.

Blood Pressure Determination↗
PubMed1992

[Plasma viscosity. The effect of plasma proteins].

The authors assessed the plasma viscosity by means of a capillary viscosimeter of their own design and assessed at the same time the concentration of 22 plasma proteins or lipids. Based on the results of these examinations it proved possible to elaborate an original equation which describes the plasma viscosity as a function of the concentration of fibrinogen, alpha-2-globulins (and among them most probably haptoglobin), gammaglobulins, IgA and IgM. The authors discuss in detail the importance of this finding for clinical haemorheology.

Blood Proteins↗
PubMed1991

Biologic markers in ethylene oxide-exposed workers and controls.

Ethylene oxide (EtO) is an alkylating agent and a model direct-acting mutagen and carcinogen. This study has evaluated a panel of biologic markers including EtO-hemoglobin adducts (EtO-Hb), sister-chromatid exchanges (SCEs), micronuclei, chromosomal aberrations (CAs), DNA single-strand breaks (SSB) and an index of DNA repair (ratio of UDS to NA-AAF-DNA binding) in the peripheral blood cells of 34 workers at a sterilization unit of a large university hospital and 23 controls working in the university library. Comprehensive environmental histories were obtained on each subject including detailed occupational and smoking histories. Industrial hygiene data obtained prior to the study and personal monitoring during the 8 years preceding the study showed that workers were subject to low-level exposure near or below the current Occupational Safety and Health Administration (OSHA) standard of 1 ppm (TWA). Personal monitoring data obtained during 2 weeks prior to blood sampling were uniformly less than 0.3 ppm (TWA). After adjusting for smoking, EtO workplace exposure was significantly (p less than 0.001) associated with EtO-Hb (a carcinogen-protein adduct) and 2 measures of SCEs [the average number of SCEs/cell (SCE50) and the number of high frequency cells (SCEHFC)]. There was an apparent suppression of DNA repair capacity in EtO-exposed individuals as measured by the DNA repair index; i.e., the ratio of unscheduled DNA synthesis (UDS) and NA-AAF-DNA binding (p less than 0.01). No association of DNA repair index with smoking was found. Another important finding of this study is the highly significant correlation between EtO-Hb adduct levels and SCEHFC (p less than 0.01) and SCEs (p less than 0.02) which provides evidence of a direct link between a marker of biologically effective dose and markers of genotoxic response. In contrast, micronuclei, CAs and SSBs were not significantly elevated in the workers. The activity of the u-isoenzyme of glutathione-S-transferase (GT) was measured as a possible genetic marker of susceptibility and a modulator of biomarker formation. However, possibly because of confounding by age, no significant relationships were found between GT and any of the exposure-related markers by ANOVA or among other independent variables by regression. This study demonstrates significant effects of low-level EtO exposure, independent of smoking history, near or below 1 ppm on multiple biomarkers and suggests that the current OSHA standard may not be adequately protective. Previously described effects of smoking on EtO-Hb adducts, SCEs and SCEHFC were also seen in this study.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

Differences in cancer-risk-related behaviors in Latino and Anglo adults.

METHODS. Latino (n = 358) and Anglo (n = 113) adults living in the San Diego area were surveyed on nutrition, smoking, and cancer screening behaviors. The Latino respondents were dichotomized into a low (L-Latino) or high (H-Latino) acculturation group according to a median split of an acculturation index. RESULTS. After controlling for age, years of education, gender, marital status, and income, significant cross-cultural differences were found in saturated fat/cholesterol avoidance, and fiber and high calorie food consumption. L-Latino respondents had the lowest degree of saturated fat/cholesterol avoidance, followed by H-Latinos and Anglos. A pattern of decreasing consumption with increasing acculturation was observed for fiber and high calorie foods. Significant differences were found among women in the prevalence of Pap smear exams, with L-Latinas having the lowest prevalence of ever and in the past year having had a Pap smear, followed by H-Latinas and Anglos. A similar significant pattern was observed among women 50 years of age or older with respect to the prevalence of ever having had a mammogram.

Adult↗
PubMed1991

Fluconazole failure in the treatment of invasive mycoses.

Fluconazole is a recently licensed antifungal agent that has gained widespread use in the medical community. Despite a lack of controlled trials in invasive fungal infections, this agent is often prescribed because of ease of administration and concern over amphotericin B toxicity. Three cases of systemic fungal infections in which fluconazole use resulted in unambiguous microbiologic and clinical failure are reported.

Amphotericin B↗
PubMed1991

Influence of antihypertensive drug therapy on sleep pattern and sleep apnea activity.

Sleep apnea, which affects 10% of men in the mean age group, is a common illness, and arterial hypertension one of its early symptoms. For the large group of, mainly young, patients with mild to moderate sleep apnea and arterial hypertension it is important to have a drug treatment available which will effectively control blood pressure without exacerbating symptoms of sleep apnea. We studied the effects of antihypertensive agents on blood pressure, sleep and sleep apnea in a randomized double-blind study of 24 patients with a sleep apnea activity of more than 10 apnea phases per hour of sleep and arterial hypertension with diastolic blood pressure values in the sitting position greater than or equal to 95 mm Hg. Mean age was 51 (range: 33-69) years, mean body mass index 31.4 (24.9-40.6) kg/m2. The study protocol envisaged two baseline measurements in the sleep laboratory, after which the medication was administered for 8 days. On the last 2 days of the treatment, polysomnographic leads were once again recorded in the sleep laboratory. The patients received either the beta-blocker metoprolol (1 x 100 mg/day) or the angiotensin-converting enzyme inhibitor cilazapril (1 x 2.5 mg/day). Systolic and diastolic blood pressure were decreased by both substances as expected. Total sleep time was 358 (233-425) min vs. 332 (255-383) min in the metoprolol group and 368 (295-424) min vs. 341 (265-434) min in the cilazapril group which is statistically not different between the two groups nor between the proportions of non-REM and REM sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗