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Biomedical subjects

D Weber

Publications and source records attributed to D Weber.

At least 19 recordsLinked to original sources
PubMed1992

Liver and brain glucocorticoid receptor in rainbow trout, Oncorhynchus mykiss: down-regulation by dexamethasone.

Total glucocorticoid binding sites were identified and quantitated in liver and brain of rainbow trout using an exchange method and [3H]dexamethasone as the ligand. Both tissues contained a predominantly cytosolic moiety that bound dexamethasone with high specificity. Binding was saturable, time dependent, and completely reversible. Scatchard analysis showed a linear relationship suggesting that receptors belong to a single class. Dexamethasone down-regulated both liver and brain receptors. Down-regulation was rapid (within hours) and dose dependent (ED50 = 1.5 mg/kg body weight). Dexamethasone-induced down-regulation was not a result of cytoplasm to nuclei translocation or due to increases in tissue concentrations of steroid. Dexamethasone administration resulted in a lowering of Bmax (82.3 +/- 2.5 to 20.6 +/- 10.5 fmol/mg protein) and an increase in Kd (15.6 +/- 0.2 to 44.3 +/- 5.0 nM) suggesting a conformational change in the receptor molecule as part of the mechanism. The brain and liver of the rainbow trout thus have glucocorticoid receptors similar to those described in the mammalian system. Further, these receptors are subjected to autologous regulation similar to their counterparts in other systems.

Analysis of Variance↗
PubMed1992

Psychophysiological reactions of patients with atopic dermatitis.

In a laboratory experiment, 20 female patients with atopic dermatitis (AD) and 20 female controls were exposed to two stress situations (watching a film about scarifications and tatooing, mental arithmetic). Recordings were made of systolic blood pressure, diastolic blood pressure, heart rate, skin conductance level (SCL), number of spontaneous (non-specific) electrodermal fluctuations (SF) and the PSI, the number of active palmar sweat glands in an area of the finger pad. Neither in the cardiovascular variables nor the PSI were any significant group differences found, neither for baseline nor stress values, nor for the response reactions. Atopic dermatitis persons had significantly lower values for SCL and SF throughout the whole experiment, although response reactions did not differ between groups. This study lends no support to the assumption of a general psychophysiological overreactivity or individual specific reactions of the skin system in patients with AD.

Adolescent↗
PubMed1992

Right ventricular conductance to establish closed-loop pacing.

Innovations in pacing technology, which include the addition of rate-responsive features to programmable pacemakers, can improve the quality of life of patients suffering from sick sinus syndrome. Among the strategies providing rate-adaptive cardiac pacing, the most attractive is the physiological restoration of closed-loop chronotropic control. This paper describes how autonomic nervous system (ANS) control information is extracted from dynamic measures of myocardial contractile performance obtained from unipolar conductance measurements using the stimulation electrode in the right ventricular cavity. The pacemaker uses the ANS information to modulate pacing rate and restore normal physiological control of heart rate. A new algorithm, regional effective slope quantity (RQ), for isolating the ANS signal was developed. The resulting signal, ventricular inotropic parameter (VIP), is a normalized parameter proportional to the strength of the ANS inotropic signals to the myocardium. The efficacy of the ANS control concept was evaluated in multi-centre studies. Patients with AV block and VIP-controlled pulse generators performed defined exercise protocols. The ANS-controlled pacing rate and the spontaneous sinus rate were closely correlated. Blood pressure and subjective patient reports further indicated that good control of the cardiovascular circulation was achieved.

Autonomic Nervous System↗
PubMed1992

Autonomic nervous system controlled closed loop cardiac pacing.

A multicenter clinical study is presented, which focuses on the reestablishment of closed loop cardiac control in patients with chronotropic insufficiency. Using the information about sympathetic tone contained in the myocardial contractility, it is possible to reconnect the heart rate to the physiological control mechanisms. Intracardiac impedance is measured with the ventricular electrode and the ventricular inotropic parameter (VIP) is derived from that. The VIP serves directly as input to the control of heart rate by the pacemaker. Over 200 patients have received autonomic nervous system (ANS) controlled pacemakers. The patient-pacemaker system was investigated in different ways. This included standard exercise tests, long-term studies of every day activities over 24 hours, psychological, and pharmacological challenges. To prove the validity of the approach we specifically looked at (1) the appropriateness of changes in paced heart rate with sympathetic tone during exercise, (2) the correlation between heart rate and sinus rate, if detectable, and (3) the correlation between the echocardiographically determined preejection period (PEP) and the VIP controlled heart rate.

Autonomic Nervous System↗
PubMed1991

Immunologic correlates of spontaneous lymphocyte proliferation in human T-lymphotropic virus infection.

Previously we showed that mononuclear cells from about half of human T-lymphotropic virus (HTLV)-seropositive persons exhibit spontaneous proliferation in vitro. We sought to determine if proliferation was associated with other immunologic changes characteristic of HTLV infection. The parameters assessed were (1) percentages of lymphocytes expressing CD4 and/or CD25 (interleukin-2 receptor), (2) serum levels of soluble CD25, (3) serostatus for other viruses, (4) anti-HTLV antibody levels, and (5) HTLV type determined by polymerase chain reaction or serologic reactivity with type-specific peptides. The proliferation+ HTLV (PROL+) group, proliferation HTLV (PROL-) group, and control group showed similar percentages of CD4+, CD25+, and CD4+CD25+ lymphocytes; serum levels of soluble CD25 were also similar. Antibodies to cytomegalovirus, hepatitis B core, and hepatitis C were present in similar proportions of PROL+ and PROL+ groups. However, a significant association was found between spontaneous proliferation and anti-HTLV antibody levels; sera from 67% of PROL+ persons, but only 18% of PROL- persons, required dilution to yield absorbance values within the linear range of the anti-HTLV antibody assay. In the PROL+ group, persons whose sera required the most dilution had proliferative responses significantly higher than those whose sera required no dilution. The PROL+ and PROL groups were similar with regard to the relative distribution of HTLV-I and HTLV-II infection. These findings indicate that HTLV-related spontaneous lymphocyte proliferation is related to levels of circulating anti-HTLV antibodies, and characterizes both HTLV-I and HTLV-II infection.

Antibodies, Viral↗
PubMed1991

Histamine and the stomach: chemical histamine assays.

Histamine assays in gastroduodenal tissues and body fluids are not an absolute objective of scientific interest but are related to the role of histamine in health and disease. Hence, the reliability of histamine assays has to be assessed in relation to this aim. Sensitivity and specificity of the chemical histamine assays are similar in tissues and body fluids. The modern developments in a fluorometric-fluoroenzymatic assay guarantee the highest sensitivity and specificity, especially by tests that monitor specificity in each single run of histamine determinations. Precision and accuracy of histamine measurement were especially investigated for the fluorometric assay. They included tests on the coefficient of variation over the whole concentration range, long-term precision with double-sample standard control charts, comparison of several methods for histamine assay including bioassay, and long-term accuracy with the use of Cusum charts. Finally, appropriate sample preparation, sample-taking, relevant body fluids and tissues, and the right time for sample-taking were evaluated in extended methodologic studies. Histamine assays are not just methods for a normal routine laboratory. Extended knowledge about histamine release and metabolism will be necessary to analyse data in this particular field with reasonable validity.

Animals↗
PubMed1991

Orthodontic anomalies and differences in gnathometric variables in twins.

Actuality of gnathometric measurements by means of plaster casts persisting to the present days is stressed and the major research of the kind in twins mentioned. The study included 96 pairs of twins of both sexes (36 monozygotic and 60 dizygotic). Both qualitative and quantitative variables were evaluated and the results computer-processed. For most parameters evaluated, statistical processing revealed a markedly higher compatibility in monozygotes than in dizygotes. This held particularly true for types and severity of anomalies as well as for all qualitative variables, with the exception of over bite, overjet, class and class severity. The maxilla-related variables were shown to be highly genetically determined, which might be explained by the dynamics of mandibular movements and, possibly, a stronger effect of external factors on its growth and development.

Adolescent↗
PubMed1991

Interpretive criteria of the Western blot assay for serodiagnosis of human immunodeficiency virus type 1 infection.

This project was designed to evaluate different criteria used in the interpretation of the human immunodeficiency virus type 1 (HIV-1) Western blot assay on a group of serum samples blinded to the examiner that were collected from individuals attending three different public health departments in central North Carolina. Each individual also completed an anonymous linked questionnaire regarding sociodemographics and risk factors for blood-borne infections. All of the Western blot assays for human immunodeficiency virus type 1 were interpreted according to the criteria established at the University of North Carolina Hospitals, Chapel Hill, the Centers for Disease Control, Atlanta, Ga, in association with the Association of State, Territorial, and Public Health Laboratory Directors, Iowa City, Iowa, the American Red Cross, Washington, DC, the Consortium for Retrovirus Serology Standardization, Davis, Calif, and the Food and Drug Administration, Washington, DC. The results obtained were grouped as positive, negative, and indeterminate according to each organization's criteria and analyzed in the context of the associated risk factors. The results indicate that institutions performing human immunodeficiency virus type 1 Western blot confirmatory testing should adopt the criteria of the Centers for Disease Control and the State, Territorial, and Public Health Laboratory Directors.

AIDS Serodiagnosis↗
PubMed1990

Effects of trihexyphenidyl on plasma chlorpromazine in young schizophrenics.

This study investigated the effects of trihexyphenidyl on chlorpromazine (CPZ) plasma levels and clinical state in 20 relatively young schizophrenic patients diagnosed using the DSM-III. Spontaneous changes in CPZ plasma levels over time were also examined. Trihexyphenidyl significantly increased CPZ plasma levels (average 41%) but did not produce clinical change. The trihexphenidyl-induced increase in CPZ plasma levels was independent of CPZ oral dosage and of CPZ plasma levels. Chlorpromazine plasma levels decreased non significantly (about 13%) over the four weeks following steady state, but there was marked inter-subject variability, and CPZ levels rose in some subjects. Although identical CPZ doses produced widely variable plasma levels, CPZ plasma levels correlated significantly with oral dose. The views that antiparkinsonian drugs interfere with neuroleptic efficacy, and do so by lowering neuroleptic plasma levels, are questioned.

Adolescent↗
PubMed1990

[Sequelae and long-term results following portasystemic anastomoses and significance of ambulatory after care].

After portocaval anastomosis 149 cirrhotic patients were treated on an outpatient basis. Liver insufficiency was observed in 24%. Encephalopathy was chronic in 14% and episodic in 11%. The most common postoperative complication was edema of the ankle (48%). Further operations bore a minimal risk (mortality 3/22). Sixty-eight percent of the patients agreed to abstain from alcohol; 85% took vacation trips and 95% were satisfied with the operation.

Aftercare↗
PubMed1990

[Monitoring respiratory and circulatory parameters in comparing various jet ventilation procedures].

Reported is a system of apparatures to control characteristic changes of cardiorespiratory function during different methods of endoscopic ventilation. The aim of the study is to measure and record simultaneously and continuously ECG, thoracic movement, tracheal pressure, pulmonary artery pressure and arterial oxygen pressure using transcutaneous technique. Measurements of arterial blood pressure and blood gas analysis (PaO2, PaCO2, BE, HCO3-, pH) are carried out in intervals. Four different methods of injector-ventilation are compared with the conventional laryngoscopic ventilation on the basis of a test program. Laryngoscopic ventilation as well as injectorventilation by CARDEN-Tubus make it possible to achieve a hyperoxaemic situation by normofrequent ventilation. Despite of hyperventilation it is not possible in every case to achieve an increased capillary oxygen pressure of 200 to 300 mm Hg by injector-ventilation with Venturi effect because of a smaller oxygen proportion. In jet-ventilation with N2O/O2-mixture (3:1) there is no appreciable hyperoxia, but a small reduction of systemic arterial blood pressure. With all techniques of mechanical respiration usual middle intratracheal pressure of respiration was not exceeded. Traumatic pressure of jets was only indirectly shown in steep rises of pressure by the applied technique of measurement.

Adult↗
PubMed1989

Reliability of a urine dipstick in emergency department patients.

We conducted a study to examine whether a negative Chemstrip 9 result for leukocyte esterase and nitrite would reliably exclude an abnormal microscopic examination of the urine of emergency department patients. Three hundred urine specimens were subjected to Chemstrip 9 evaluations and full microscopic examinations in the microscopy laboratory. As the microscopy laboratory examination identified lower WBC and bacteria counts, increasing numbers of false-negative urine dipsticks results occurred. The results of our study reveal that the nitrite and leukocyte esterase assays miss significant microscopic findings with corresponding clinical pathology, with the nitrite examination being the less sensitive of the two tests. Based on our results, we believe it would not be prudent to use the Chemstrip 9 dipstick in the ED to exclude the presence of WBC and bacteria in the urine.

Bacteriuria↗
PubMed1989

Mapping RFLP loci in maize using B-A translocations.

Plants hypoploid for specific segments of each of the maize (Zea mays L.) chromosomes were generated using 24 different B-A translocations. Plants carrying each of the B-A translocations were crossed as male parents to inbreds, and sibling progeny hypoploid or not hypoploid for specific chromosomal segments were recovered. Genomic DNAs from the parents, hypoploid progeny, and nonhypoploid (euploid or hyperploid) progeny for each of these B-A translocations were digested with restriction enzymes, electrophoresed in agarose gels, blotted onto reusable nylon membranes, and probed with nick-translated, cloned DNA fragments which had been mapped previously by restriction fragment length polymorphism (RFLP) analysis to the chromosome involved in the B-A translocation. The chromosomal segment on our RFLP map which was uncovered by each of the B-A translocations was determined. This work unequivocally identified the short and long arms of each chromosome on this map, and it also identified the region on each chromosome which contains the centromere. Because the breakpoints of the B-a translocations were previously known on the cytological and the conventional genetic maps, this study also allowed this RFLP map to be more highly correlated with these maps.

Centromere↗
PubMed1989

[Measurement of handicap in the community: a micro survey in a French village].

Handicap is the result of a process initiated by an underlying disease, an accident or an abnormality, which leads to a functional deficit in various situations of everyday life. This definition, derived from the International Classification of Impairments, Disabilities, and Handicaps (ICIDH), reflects the desire of the elderly and the handicapped for social integration. It may also form the conceptual basis for analysis of the capacities of individuals and populations. To this end, a micro-survey was conducted in a homogeneous village community of 532 people aged 1-92 years. This study was of the ergonomic type, accompanied by a questionnaire on perceived restrictions and handicaps, and carried out transversely over a period of one month (94.7% participation). The specific objectives of the study were to obtain a reliable functional representation of the population of the village, comparing self-assessment of functional capacity with observed performance, and analysing the effects of age on capacity. The copious data collected in the areas of locomotion, prehension and communication have provided a detailed functional profile of the population studied. These data may be transposed to particular environments, such as transport, housing, school or work, and may serve as a basis for comparisons. The difficulties encountered by subjects in the tests were closely correlated with the situations simulated by the tests. Subjective estimation of handicap proved to be reliable in comparison with actual performance, especially for tests of mobility and highly demanding situations. Estimation of the presence of a handicap increased with age. The deterioration in performance observed was proportional to age, but can be perceived to begin early, at about 30-40 years. Disability-free life expectancy (DFLE) could be an interesting indicator in so far as it appears to be sensitive to the confrontation of individual functional capacities with the environment. However, it is important that any disability used as a basis for calculation should be measured with maximum precision. A community survey of this kind is thus particularly useful for ergonomic purposes, but is also valuable for the planning of medical and social assistance at the local level in the areas of disability and handicap. The combination of observation and listening to people, with an interview, appears to be fruitful and reliable. Single studies of well-targeted samples of the population, or, alternatively, of larger and more significant populations, would be desirable in public health, since the epidemiological approach to handicap has hitherto been essentially focused on diagnosis and medical evaluation.

Activities of Daily Living↗