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Biomedical subjects

H Kramer

Publications and source records attributed to H Kramer.

At least 19 recordsLinked to original sources
PubMed1992

Subtilisin removes the surface layer of the phage fd coat.

The major coat protein of native filamentous phage fd is vulnerable to digestion by subtilisin, but not by any of a number of other proteolytic enzymes. Degradation by the non-specific protease subtilisin occurs at specific sites in the N-terminal portion of g8p. The N-terminal part of the protein is considered to be the outer layer of a two-layered coat. Thus, subtilisin treatment results in a monolayered phage particle. These particles possess the morphology and stability of native phage fd. Furthermore, subtilisin proteolysis proved to be an efficient instrument in detecting variations in the topology of the g8p of related filamentous phages.

Amino Acid Sequence↗
PubMed1992

Fatigue during sustained maximal voluntary contraction of different muscles in humans: dependence on fibre type and body posture.

Nine healthy men, aged between 25 and 35 years, performed sustained maximal voluntary contractions (MVC) of foot plantar, foot dorsal, and finger flexor muscles. Contractions lasted 10 min and were followed by short test contractions at 30% MVC during recovery. Two positions of the working extremity high or low were established by different body postures (supine or sitting). Under these conditions, studies of force, integrated electromyogram (iEMG), blood pressure, and heart rate showed firstly that force decreased throughout the first few minutes of maximal contraction but reached a near steady-state value after 5 to 6 min. Secondly, force decay and steady-state level depended on muscle group and body position. When sitting (low leg), muscles with a high incidence of slow twitch fibres (plantar flexors) showed a slower force decay and a higher relative steady-state force than fast dorsal flexor muscles. When supine (high leg), plantar and dorsal flexor muscles reached about the same low level of relative steady-state force. Changes in iEMG, blood pressure, and heart rate did not differ in the two positions. Thirdly, during recovery, plantar flexor muscles showed higher iEMG values as well as higher values of blood pressure and heart rate when supine than when sitting. Recovery of dorsal flexor muscles was little affected by body posture. Fourthly, force development and recovery of predominantly fast finger flexor muscles were almost independent of arm position. It was concluded that muscle fibre composition was the main factor in determining endurance capacity. However, endurance was influenced by changes in the hydrostatic blood pressure component.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Myopathy in Williams-Beuren syndrome.

Williams-Beuren syndrome (WBS) is a disorder of unknown aetiology. The classical features of the syndrome include a typical ('elfin') facies, mental retardation and heart defects. Myopathy has not so far been part of the spectrum of WBS. We studied six patients with WBS aged 3-25 years, five of whom showed clinical and morphological evidence of myopathy. The clinical manifestations of myopathy included hypotonia in infancy, walking delay, joint contractures, scoliosis, and increased exhaustion on exertion. These symptoms were present in variable expression but part of a typical postural pattern. Examination of muscle biopsies showed lipid storage in four patients and increased variability of fibre size in three. In one patient a muscle biopsy gave normal results. Biochemical investigation in four patients with morphological evidence of lipid storage in muscle revealed muscle carnitine deficiency in three. In addition, enzyme activities of fatty acid beta-oxidation were low in one of two specimens tested. It is concluded that a clinically relevant myopathy is part of the multi-system manifestation of WBS and a clinical trial of carnitine supplementation is justified.

Adult↗
PubMed1989

Force, endurance time, and cardiovascular responses in voluntary isometric contractions of different muscle groups.

A study was made to reinvestigate the general validity of the force/endurance relation of isometric contractions. Relative force development, mean bioelectrical muscle activity and circulatory responses (blood pressure, interbeat interval) during isometric contractions of different muscle groups were compared. 6 men performed maximum isometric contractions of foot plantar- and dorsalflexors and hand flexors lasting 10 minutes. The hydrostatic blood pressure was varied by placing subject's arms and legs in two different positions, high and low. 9 Women performed plantarflexion and dorsalflexion with maximum strength and at constant load of 60% MVC to exhaustion. The results confirm that the force/endurance relationship during isometric exercise is not a biological constant, applicable for all muscles. The fibre composition of the muscle and the blood pressure varied by different hydrostatic components are discussed as factors causing differences in force/endurance relationship.

Adult↗
PubMed1987

Neurological manifestations in three German children with AIDS.

We report the neurological findings in two children with AIDS and one child with lesser AIDS. The first patient developed acute encephalopathy 37 months after having received a blood transfusion from a HTLV-III positive donor. CCT showed ring-enhancement and hypodense lesions with homogenous enhancement. Autopsy revealed CNS toxoplasmosis. The second child with AIDS, born to an iv drug-addicted mother, had one seizure at four months of age, but other neurologic signs were absent. She died of pneumonia due to Pneumocystis carinii at seven months of age. Postmortem examination of the brain revealed extensive nerve cell damage in the cerebral cortex and cerebellum, probably due to terminal hypoxemia and not AIDS-related. In both children clinical features of childhood AIDS like failure to thrive, lymphadenopathy, oral thrush and chronic pulmonary infiltrates were absent. The hallmark of the third child's clinical course was a progressive loss of psychomotor abilities with onset of the neurological symptoms nine months before other signs of AIDS occurred. AIDS should be suspected or excluded in children at increased risk for AIDS presenting with either acquired atypical CNS infection or unexplained developmental regression, even in the absence of other clinical symptoms of pediatric AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Complex arrhythmias in mitral regurgitation with and without mitral valve prolapse: contrast to arrhythmias in mitral valve prolapse without mitral regurgitation.

Atrial and ventricular arrhythmias were characterized by ambulatory electrocardiography in 31 patients with nonischemic mitral regurgitation (MR), 17 of whom had echocardiographic evidence of mitral valve prolapse (MVP) and 14 of whom had other causes of MR. Frequent and complex arrhythmias were common and equally prevalent in each MR subgroup, whether or not MVP was present. Multiform ventricular ectopy was found in 77% (24 of 31), ventricular couplets in 61% (19 of 31), and ventricular salvos or ventricular tachycardia in 35% (11 of 31) of patients with MR. Arrhythmias in patients with MR were significantly more prevalent than in 63 patients with MVP who had no evidence of MR. Among patients with MVP, excess arrhythmias associated with MR were most striking with respect to frequent ventricular premature complexes (41% with MR vs 3% without MR), multiform ventricular ectopic activity (88% vs 43%), ventricular couplets (65% vs 6%), and ventricular salvos or ventricular tachycardia (35% vs 5%) (p less than 0.005 for each comparison). These data demonstrate that complex arrhythmias are common in patients with nonischemic MR irrespective of etiology, and that these arrhythmias are more strongly associated with hemodynamically important MR than with MVP alone.

Adult↗
PubMed1979

[Immunologic diagnosis].

The development of the immunologic basic research and a deeper insight into the pathogenesis of diseases with changed immune reactivity led to an intensivation of the clinic-immunologic in-vivo- and in-vitro-diagnostics. At the instance of the pulmonary diseases according to the classification of Gell and Coombs the immunologic-diagnostic possibilities and problems are shown. Here is referred to the importance of the use of standardized tests and of the wide replaceability of in-vivo-techniques by in-vitro-methods.

Anti-Glomerular Basement Membrane Disease↗