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Biomedical subjects

G Albrecht

Publications and source records attributed to G Albrecht.

At least 55 records · Page 3Linked to original sources
PubMed1992

CD36 peptides enhance or inhibit CD36-thrombospondin binding. A two-step process of ligand-receptor interaction.

CD36 (glycoprotein IV or IIIB) is an integral plasma membrane protein of wide cellular distribution and functions as a receptor site for thrombospondin (TSP), an adhesive protein important in cell-cell and cell-matrix interactions. OKM5, a monoclonal anti-CD36 antibody, has been reported to block CD36 cell adhesive functions suggesting that the OKM5 epitope on CD36 is functionally important. A panel of 10 synthetic CD36 peptides was made. One peptide, P139-155, specifically inhibited the immunoadsorption of CD36 by OKM5, and P139-155 was directly immunoadsorbed by OKM5, indicating that CD36 sequence 139-155 represents part of the OKM5 epitope. TSP bound to immobilized P139-155 in a dose-dependent and saturable manner. Surprisingly, P139-155 significantly augmented, instead of inhibited, binding of CD36 to TSP. This peptide did not induce platelet aggregation but augmented ADP- and collagen-induced aggregation in platelet-rich plasma. Another CD36 peptide, P93-110, which had no effect on OKM5 immunoadsorption, blocked binding of CD36 to immobilized TSP and partially inhibited collagen-induced platelet aggregation. P93-110 by itself did not bind to TSP; however, in the presence of P139-155, there was a marked enhancement of P93-110 binding to TSP, with a stoichiometry consistent with the trimeric nature of TSP. The data suggest that CD36-TSP interaction is a two-step process; the sequence 139-155 region of CD36 binds first to TSP, triggering a change in TSP to reveal a second site, which binds the 93-110 region of CD36 with high affinity. CD36 peptides can be used as stimulators or inhibitors in cellular adhesive events involving TSP-CD36 interaction. Conformational changes leading to the exposure or activation of high affinity binding sites may occur in both the receptor and the ligand upon cell-cell and cell-matrix adhesion.

Amino Acid Sequence↗
PubMed1992

[Stabilization and function of liposomes].

Liposomes stability can be improved by covering them with polysaccharide derivatives. The anchoring mechanism of these derivatives into the lipid membrane has been studied and explained. In order to improve liposome specificity, protein transfer from erythrocytes and platelets into liposome membrane has been carried out. The effect of a newly developed phospholipid, DDPC, on the efficiency and the selectivity of protein transfer is reported.

Blood Platelets↗
PubMed1991

Concern about AIDS among hospital physicians, nurses and social workers.

In this study, the authors examine the worry and discomfort experienced by direct care health professionals in treating AIDS patients and how their profession, attitudes, knowledge, experience and demographic characteristics influence their emotional reaction to those patients. The research focuses on experienced emotion as distinct from expressed emotion, as an important factor in explaining health behaviors among professionals. To address these issues 536 health care professionals comprising 132 physicians, 378 nurses and 26 social workers employed at a University teaching hospital in Chicago were surveyed. The findings suggest that health care workers' emotional reactions to HIV depend on the type of patient interaction. We found for all three professions, as the invasiveness of contact increased, the level of worry and amount of discomfort also increased. Nurses however, on the whole were the most adversely affected by their patient contacts. We conclude that emotional reactions in the workplace cannot be explained by cognitions, beliefs and attitudes alone. This study suggests that work roles, work assignments, and professional authority contribute to emotional reactions to patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Incidence and mortality of malignant melanoma in Berlin (West) from 1980 to 1986.

Newly diagnosed melanomas were investigated utilizing the histological reports from the 4 Departments of dermatology as well as from 3 Departments of pathology in Berlin (West) during the years 1980-86. The study included 960 melanomas and documented the histological features, age, gender and nationality of the patients involved. 936 patients were Germans (379 males, 557 females), and the mean age-adjusted incidence rate (for the European standard population) was 7.1 cases per 100,000 inhabitants and year for both genders with an increase between 1980-81 and 1985-86 in men from 6.0 to 9.8 and in women from 5.8 to 7.8/100,000 and year. Thus a 49% increase in incidence was observed for both genders combined during a 5-year period. In this study, a preponderance of male incidence rates was observed for the first time in Germany. Interestingly, the age-adjusted incidence rate for the Turkish population, which is the largest foreign population with more than 100,000 inhabitants in Berlin, was only 1.3/100,000 and year. 162 men and 145 women died of melanoma in the time period examined. From 1980-81 to 1985-86, the age-adjusted mortality rate changed from 3.5 to 2.6 for men and from 1.2 to 1.6 for women per 100,000 and year, thus revealing a slight decrease in mortality for both genders combined.

Adult↗
PubMed1991

[Quantitative histologic studies of the gonads of sand rats (Psammomys obesus) during the development of diabetes mellitus].

Quantitative-histological investigations (point counting method) are pointed out in 27 male and 15 female sand rats. The animals are divided in the IGT (impaired glucose tolerance), the diabetic and the control group. The LEYDIG cells are in the IGT-group increased, and in the diabetic group decreased. The female sand rats are characterized by the tendency of increase of size and number of follicles in the IGT-group. Corpora lutea are reduced but atretic follicles are increased in the diabetic group. The ovaries are greater in diabetic sand rats.

Animals↗
PubMed1990

KADIS--a computer-aided decision support system for improving the management of type-I diabetes.

Despite the introduction of new therapeutic aids such as insulin pumps and injectors, blood glucose test tapes, particular insulin formulations, and the physiological basis-bolus principle of insulin dosage regimes, the metabolic care of most insulin-dependent patients is still insufficient. One potential tool of further improving the results in diabetes treatment consists in the application of computer-aided procedures to estimate individually optimal regimes. Employing a validated mathematical model of the glucose/insulin metabolic control system and individual sets of data from patients' self-monitoring, a software package was developed on a micro-computer which allowed both the retrospective analysis of data resulting from the therapeutic process, and the prospective simulation of the outcome of alterations in the regime in terms of glycaemia and insulinaemia. The two parts of the programme provide either for the patient or for the physician an interactive mode of working with the computer. The system is now being validated by means of a long-term follow-up study in type-I diabetic patients. It may be used mainly in diabetic outpatient centers and as a tool of educating, training, and motivating patients.

Computer Simulation↗
PubMed1990

Determinants of self-perceived risk for AIDS.

This paper examines self-perceptions of risk for AIDS and factors that contribute to estimations of risk. On the basis of a telephone survey of 1,540 adults age 18 to 60, we address the question: What heuristic factors predict perception of risk for AIDS? Results show that five heuristic categories determine self-perceptions of risk: sexual practices, moral evaluations of people with AIDS, emotional response to AIDS, protective actions in response to AIDS, and demographic characteristics. Number of sexual partners over the past five years and knowledge of sexual partners' past sexual behavior are associated significantly with increased perceptions of risk. Fear of AIDS and worry about one's health also contribute significantly to self-perception of risk, as does shame associated with having AIDS. Asian-Americans and persons with no particular religious affiliation report greater perceptions of risk. These findings call attention to heuristic factors in considering theories of risk and in designing interventions to change preventive actions associated with high risk for AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1990

[A low-cost localization technique for high-dose-rate afterloading applicators].

For radiation safety control radiotherapy today needs a method to check the correct position of a HDR-gynecological applicator before afterloading treatment. At the university clinic in Essen, West Germany, a surgical c-X-ray plant was used for the construction of an orthogonal X-ray-photograph plant, which combines illumination and photographs as localisation technique.

Brachytherapy↗
PubMed1990

A model-based system for the individual prediction of metabolic responses to improve therapy in type I diabetes.

Despite recent achievements such as home glucose monitoring and intensified injection regimens or insulin pumps, the metabolic care in diabetic patients is still mostly insufficient. One approach of further improving the management is the application of computer-aided procedures to estimate individually the optimal regimes. To accomplish this, a model-based strategy was developed which permits the prospective assessment of the metabolic outcome. This strategy comprises the following components: (1) a validated model of the physiological glucose-insulin regulatory system; (2) a procedure for identifying the metabolic situation of a given patient in terms of the model parameters; (3) methods of estimating the pharmacokinetics of insulin and its effect on glycemia, the absorption profiles of ingested glucose equivalents, and the effect of exercise as expressed in equivalents of insulin action; (4) computer procedures of prospective simulation of glycemic profiles around the day under the influence of selected or proposed therapeutic regimes. The entire method has been validated in C-peptide negative type I diabetic patients by comparing experimental results with theoretical predictions from model-based simulations over up to one year. This model-based simulation may be applied by ambulatory patients together with their physicians as a decision-support system in selecting appropriate individually suited regimes.

Blood Glucose↗
PubMed1989

In situ calibration of implanted electrochemical glucose sensors.

A feasible and reliable method of in situ checking and calibration of implanted glucose sensors is required to compensate for alterations in the overall sensitivity of the "sensor plus subcutaneous fluid glucose compartment" system. In a study on nondiabetic dogs, the linear regression analysis of paired plasma glucose/sensor current data is validated as a potential basis of recalibration of intracorporal glucose sensors. These sensors were amperometric glucose oxidase/hydrogen peroxide electrodes of which the in vitro response time to square alterations in the ambient glucose concentration T95 was less than 5 min. The method presented may be incorporated into the data handling system of portable glucose monitors or of miniaturized artificial beta-cells. For its performance, no steady state glycaemia but a minimum alteration in the intracorporal glucose concentration is needed. The latter can be provided both by tests or by fluctuations as they occur spontaneously during the course of the day.

Animals↗
PubMed1988

Genomic footprinting detects factors bound to major late and IVa2 promoters in adenovirus-infected HeLa cells.

We used DNase I footprinting assays on nuclei isolated from adenovirus-infected cells to examine the nucleoprotein configuration of a 250-base-pair segment which encompasses the adenovirus type 5 major late (ML) and IVa2 promoters. At 12 and 20 h postinfection (p.i.), fine DNase I digestion mapping of wild-type adenovirus-infected cells revealed specific sequences protected from digestion which corresponded to promoter elements required for expression of the ML gene in vivo. At 12 h p.i., a G+C-rich region which lies upstream of the IVa2 cap site and is important for maximal IVa2 activity was also found masked to nuclease activity. At 20 h p.i., however, this element became more sensitive to nuclease attack, while the ML promoter elements stayed protected. No major changes in DNA-protein interactions were detected in the region spanning the ML and IVa2 cap sites upon promoter activation, suggesting that the binding properties of the cognate factors for this region are not modified during the process.

Adenoviruses, Human↗