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Biomedical subjects

L Vogt

Publications and source records attributed to L Vogt.

At least 73 records · Page 4Linked to original sources
PubMed1991

BB/O(ttawa)K(arlsburg) rats: features of a subline of diabetes-prone BB rats.

The development of incidence and age at onset of diabetes as well as the breeding performance and other phenotypic traits of the BB/O(ttawa)K(arlsburg) rat subline are assessed in relation to degree of inbreeding and mating system. With increasing inbreeding body weight decreased and striking changes were observed in incidence and age at onset of diabetes, whereas breeding performance remained largely unchanged. Because the rats were free of most of the relevant pathogens and the transfer of BB rats into a germ-poor environment with the aid of wet hysterectomy had no effect on incidence and age at onset of diabetes, a segregation of diabetogenic genes rather than an influence of environmental factors is supposed to be responsible for both the varying traits.

Aging↗
PubMed1990

Nitrogen partial pressures in man after decompression from simulated scuba dives.

In five subjects arterial and central venous nitrogen partial pressures (PN2) were measured after decompression from a chamber dive following a decompression schedule for scuba diving. The simulated dives consisted of exposure at rest to air at 6 bar for 30 min. corresponding to a depth of 50 m. Afterwards the subjects were decompressed with decompression stops at 2.5, 2.2, 1.9, 1.6 and 1.3 bar with a total decompression time of 73 min. Immediately after decompression and every 40 min. until the 240th min. arterial and central venous blood samples were analyzed for PN2 using a manometric Van Slyke apparatus. Venous PN2 remained elevated until 160 min. after decompression indicating still incomplete nitrogen wash-out at least two hours after decompression had been accomplished. Bubble formation is discussed as a cause for prolonged nitrogen elimination. Our data confirm that nitrogen elimination is prolonged after decompression from simulated dives at rest.

Arteries↗
PubMed1990

New congenic rat strains for the separate study of MHC and non-MHC genetic effects in the development of diabetes in BB rats.

Diabetes in BB rats is genetically determined by at least two genes, the one gene mapping to the MHC, the other residing in the genetic background. In order to be able to study the role of MHC and non-MHC genes in diabetogenesis we have established rat strains which combine the diabetes-resistant LEW genetic background with the RT1u haplotype of diabetic BB rats (LEW.1BB) or carry the diabetes-resistant RT1 haplotype of LEW.1A rats on the diabetic BB genetic background (BB.1A). BB rats of two different sublines (BB/OK and BB/PhiK) were used for this purpose. In these rat strains diabetes relevant traits were studied longitudinally, the RT1 haplotypes were analyzed at DNA level and 18 non-MHC linked immunogenetic and enzyme loci were monitored. The results demonstrate the successful transfer of genes with potential relevance for diabetes development in BB rats.

Animals↗
PubMed1990

[Quantitative two-dimensional echocardiography. Study results in patients with cystic fibrosis].

15 patients with cystic fibrosis aged 8-19 years were graduated into 3 stages of the cor pulmonale dependent on results of an examination with the microcatheter: stage 0:6, stage I: 4 and stage II: 5 patients. These patients were studied in the period from April 1987 to January 1988 echocardiographically. With this size and contractility of the right ventricle were especially considered. The end-diastolic and end-systolic area of the right ventricle could be measured in the apical 4-chamber-view in 14 of the altogether 15 patients and out of this the fractional area-shortening could be calculated. The end-diastolic area of the right ventricle in the patients with stage 0 was on an average 11.4 cm2/m2 body surface bs (8.7-13.5), in stage I 11.2 cm2/m2 bs (9.2-13.5), and in stage II 9.7 cm2/m2 bs (9.0-10.8). The end-systolic area of the right ventricle in stage 0: 7.2 cm2/m2 bs (6.8-8.4), stage I: 7.1 cm2/m2 bs (6.0-8.5), and stage II: 8.02 cm2/m2 bs (6.4-10.1). The results we found don't differ significantly in the 3 groups. Contrary to this fractional area-shortening of the right ventricle shows a falling tendency: stage 0.35.2% (22-49), stage I 32% (7-56), stage II 17.2% (4-38) with an increasing part of patients with a value under 28% (stage 0:1 patients, stage I 2 patients, stage II 3 patients). Contractility and pump-efficiency of the left ventricle were calculated in the apical 4-chamber-view according of the area-length-method. The findings don't show an increasing size of the right ventricle in the sense of a cor pulmonale but a decreasing contractility and pump-efficiency of the right ventricle as expressions of a cardial manifestation of the basic illness in the sense fo a symptomatic cardiomyopathy. A disturbance of the contractility of the left ventricle could be seen in 7 of the 15 patients (47%).

Adolescent↗
PubMed1990

Coat colour phenotype, leucopenia, and insulin-dependent diabetes mellitus (IDDM) in BB rats.

Susceptibility to IDDM in BB rats is linked to the MHC and to one or two non-MHC genes. It is postulated that one of the non-MHC genes is leucopenia inherited as autosomal recessive trait which is, at least in part, due to the absence of RT6.1 T lymphocyte subsets. Because the RT6 alloantigenic system is located near the coat colour gene c, we analyzed the coat colour genes of BB rats by production of F1 and F2 hybrids by crossing of three diabetic and leucopenic BB/OK females (RT1u) with one diabetes-resistant and non-leucopenia DA male (RT1av1) genetically defined by the coat colour genotype AABBCCHH. The coat colour phenotype and the RT1.A haplotype were determined in all 144 F2 hybrids. Furthermore, PMNL, body weight gain and plasma glucose were monitored up to an age of 30 weeks of life. At an age of 30 weeks the pancreatic insulin content was determined. The results let us assume that, (a) the coat colour genotype of BB/OK rats is defined as aaBBcchh, (b) the RT6 locus is not responsible for the leucopenia in BB/OK rats and (c) there is a third gene in the diabetes development of BB/OK rats which is probably not linked to one of the coat colour genes.

Animals↗
PubMed1990

Effects of randomization masking diabetes relevant traits in animal experiments.

Several randomization procedures were tested to verify effects on diabetes-relevant traits (pancreatic insulin content (PIC), glucose tolerance (GT), incidence and age at onset of diabetes), which were calculated as mean +/- SD for each group. Estimation of PIC and GT were performed in LEW.1W/MaxK and BB/OK rats of our own inbred colonies. Furthermore, BB/OK rats were monitored for onset of diabetes. Significant differences between four (LEW.1W/MaxK and BB/OK for PIC) and 12 (BB/OK) litters and between groups arranged by several randomization procedures could be observed. Comparisons of first and second litters of the same parents in BB/OK rats suggest that, using these litters, significant differences between arranged groups can be excluded. Effects of randomization have to be considered in planning and performing experiments as well as in the interpretation of experimental results.

Aging↗
PubMed1990

Nitrogen partial pressures in man after decompression from simulated scuba dives at rest and during exercise.

In 5 subjects arterial and central venous nitrogen partial pressures (PN2) were measured after decompression from a chamber dive following a decompression schedule for scuba diving. The simulated dives consisted of exposure to air at 6 bar for 30 min corresponding to a depth of 50 m. Afterward the subjects were decompressed with decompression stops at 2.5, 2.2, 1.9, 1.6, and 1.3 bar with a total decompression time of 67 min. In 3 of the subjects the measurements were repeated after they had exercised (workload 75 W) during bottom time. Immediately after decompression and every 40 min until Minute 240 arterial and central venous blood samples were analyzed for PN2 using a manometric Van Slyke apparatus. Venous PN2 remained elevated until 160 min after decompression, indicating still incomplete nitrogen washout for at least 2 h after decompression had been accomplished. We did not find any difference in PN2 values after decompression from dives at rest and after exercise. Applying a computer program based on a wide range of theoretical tissue half-times nitrogen elimination proved to be consistent with Haldanian theories when using our decompression profile. Our data confirm that nitrogen elimination is prolonged after decompression from simulated dives at rest and after exercise.

Adult↗
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↗
PubMed1987

Genetic heterogeneity in different BB rat subpopulations.

Two different BB-rat subpopulations were followed over 7 inbred generations under identical environmental conditions: BB/OK as derived in 1983 from the original stock in Ottawa, BB/PhiK as derived in 1983 from a stock at the University of Pennsylvania, Philadelphia. They showed significant differences in incidence, age at onset, untreated survival time of diabetes, leucopenia and body weight gain. By crossing experiments these phenotypical differences could be attributed to a genetic diversity between the 2 subpopulations. It is concluded that this genetic diversity is based on the heterogeneity of the parental BB Wistar rat stock and that the genetic differentiation between subpopulations of a different history is favoured by the "bottle neck effect", selection, mutation and genetic drift. The study of defined subpopulations and of their genetic interaction will provide deeper insight into the mechanisms of inheritance of diabetes in different species.

Animals↗
PubMed1980

[Investigations on the tolerance and reliability of contact lenses in air and space travel (author's transl)].

It is still forbidden by German law for cockpit aircrew to wear contact lenses. This is due in particular to experience gathered in the past with older types of contact lenses, especially those made of glass or PMMA. Meanwhile, technological progress has brought improvements in respect of material, size, tolerance and particularly the optical result. Investigations were carried out with regard to the tolerance of contact lenses in condition of low humidity, high g and sudden compression. The results are given and the consequences for cockpit aircrew and passengers are discussed.

Adult↗