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Biomedical subjects

V Weiss

Publications and source records attributed to V Weiss.

At least 37 records · Page 2Linked to original sources
PubMed1990

Bivalent effects of human growth hormone in experimental myocardial infarcts. Protective when administered alone and aggravating when combined with beta blockers.

Human growth hormone (hGH) administered alone revealed itself as a useful drug to prevent ventricular aneurysm formation in experimental myocardial infarctions in rats and is also able to diminish and change the usually expected pattern of wall necrosis. A protective action on the collagen framework of myocytes has been confirmed as one of the main causes responsible for the above mentioned findings. There are other positive metabolic actions on the myocardial cell although not completely known yet. These actions are revealed by an atypical picture of infarction which appears regionally reduced and with a patchy intracellular distribution. In an opposite fashion, when hGH was administered together with beta blockers, a rapid and extensive deleterious action occurred at the ventricular wall, a very high incidence of ventricular aneurysms and an increased extension of myocardial infarcts were the most outstanding features. The histologic picture in this series resembles that of a rapidly evolving diabetic cardiomyopathy.

Adrenergic beta-Antagonists↗
PubMed1990

The spatial metric of brain underlying the temporal metric of EEG and thought.

Multiplying memory span by mental speed, we obtain the information entropy of short-term memory capacity, which is rate-limiting for cognitive functions and corresponds with EEG power spectral density. From psychometric and EEG data follows a fundamental of about 3.14 Hz. The number of harmonics (n = 1, 2,...,9) is identical with memory span, and the eigenvalues of the EEG impulse response are represented by the zero-crossings up to the convolved fundamental, the P300. The difference T of 4.42 ms between the 8th and the 9th harmonic is the smallest time window of conscious information processing. Shannon's sampling theorem allows the replacement of any band-limited signal by m discrete sequences of T without loss of any information. Brain architecture can be understood in terms of sequences of delaying chains. Acting as a wavefront tracking array, scaled in relation of mT and in such a way also expressing the metric of eigenvalues, widths of orientation columns match with phase reversal after a zero-crossing and lengths of dendritic trees with run-length of travelling harmonics.

Brain↗
PubMed1988

Plasma serine proteinase inhibitors (serpins) exhibit major conformational changes and a large increase in conformational stability upon cleavage at their reactive sites.

Intact and proteolytically modified human serpins, alpha 1-proteinase inhibitor, antithrombin III, alpha 1-antichymotrypsin, and C1 inhibitor, were compared by circular dichroism, fluorescence spectroscopy, and resistance against unfolding by guanidine HCl. The modified proteins were prepared from the intact and active inhibitors by selective proteolytic cleavage in their reactive site loops and tested for complete loss of activity. Significant differences in the spectral properties between intact and modified inhibitors indicate that a major conformational rearrangement is triggered by the cleavage. This leads to a large increase in conformational stability as demonstrated by large shifts of the transition profiles recorded as a function of guanidine HCl concentration at 20 degrees C by circular dichroism at 220 nm. Intact inhibitors were unfolded in two steps of about equal size centered at 0.8-1.7 and 2.5-3.5 M concentrations of the denaturant, respectively. Under identical conditions modified inhibitors are completely stable, and their denaturation occurs only well above 4 M guanidine HCl in one or two steep transition steps. From the similarity of the spectral changes and shifts in transition profiles for all four serpins studied it is concluded that the conformational changes and stabilization triggered by the modification hit is an important common mechanistic feature of this class of inhibitors. This is supported by the observation that ovalbumin, which is homologous with the serpins but apparently lacks inhibitory activity, exhibits neither spectral changes nor a significant change in stability upon proteolytic modification.

Algorithms↗
PubMed1988

Phosphorylation of nitrogen regulator I (NRI) of Escherichia coli.

It has previously been shown that phosphorylated nitrogen regulator I (NRI-phosphate) is the activator responsible for increasing the transcription of glnA, the structural gene for glutamine synthetase, and that NRII catalyzes the transfer of the gamma-phosphate of ATP to NRI. We have now shown that the reaction of ATP with NRII results in the reversible transfer of the gamma-phosphate of ATP to a histidine residue of NRII. In turn, NRII-phosphate transfers its phosphate reversibly to an aspartic residue of NRI. NRI-phosphate is hydrolyzed to NRI and inorganic phosphate in a divalent cation-requiring autocatalytic reaction.

Adenosine Diphosphate↗
PubMed1987

[Immunologic aspects in disorders of male fertility].

The spermatozoa may in some circumstances induce immunological response mechanisms and evoke sperm autoimmunization. Different types of sperm antigens can be found in the seminal fluid and on the spermatozoa. New techniques: the radio-immunoassay (RIA) and the enzyme linked immunosorbent assay (ELISA) become more and more significant in the detecting of spermaantibodies. In some cases genital infections presented at the same time can be treated. Common use is the empirical therapy with steroids, successful in about 30%. May be in future a specific immunotherapy with allergenic extracts is possible.

Antigens↗
PubMed1986

Functional model of subcomponent C1 of human complement.

The domain organization of the zymogen subunits of the first component of human complement C1s, C1r2 and the complex C1s-C1r2-C1s was studied by electron microscopy. In the absence of Ca2+, monomeric C1s was visualized as a dumb-bell-shaped molecule consisting of two globular domains (center-to-center distance 11 nm) connected by a rod. One of the globular domains is assigned to the light chain (B-chain) of the activated molecule, which is homologous to trypsin and other serine proteases. The second globular domain and the rod are assigned to the heavy chain (A-chain) of CIs. The subunit C1r is a stable dimer in the presence or absence of Ca2+. This dimer C1r2 was visualized as composed of two dumb-bells of dimensions similar to those observed for C1s. These are connected near the junctions between the rod and one of the globular domains. This leads to the structure of an asymmetrical X with two inner closely spaced globules (center-to-center distance 7 nm) and two outer globules at a larger distance (14 nm). By comparison with fragment C1rII2, in which part of the A-chain is removed, the inner globular domains were assigned to the catalytic B-chains. This characteristic structure of C1r2 is readily recognized in the central portion of the thread-like 54 nm long C1s-C1r2-C1s complex formed in the presence of Ca2+. By affinity-labeling of C1s with biotin and visualization of avidin-ferritin conjugates in the reconstituted complex, it was demonstrated that C1s forms the outer portion of the complex. A detailed model of C1s-C1r2-C1s is proposed, according to which two C1s monomers bind to the outer globes of C1r2 by contacts between their heavy chains and those of C1r. According to this model the catalytic domains of C1r are located in the center and those of C1s at the very tips of the C1s-C1r2-C1s complex. On the basis of the structure of C1s-C1r2-C1s, we derived a detailed model of the C1 complex (composed of C1q and the tetrameric complex) and we discuss this model with a view to finding a possible activation mechanism of C1.(ABSTRACT TRUNCATED AT 400 WORDS)

Complement Activating Enzymes↗
PubMed1986

[Retrospective evaluation of the findings in male fertility disorders with special reference to spermiograms and hormone analyses].

736 ejaculates from 384 patients in the andrological outpatient clinic in Giessen were classified in fertile, subfertile and infertile Groups. Regarding volume, pH-value and fructose content of the ejaculate no differences were found among the three groups. Important for the classification is sperm count/ml and the progressive motility. Additional Hormone analyses showed a negative correlation between sperm count and FSH-Values. Disturbances in spermiogenesis are often connected with high LH-Values.

Follicle Stimulating Hormone↗
PubMed1984

[Characteristics of middle-latency auditory evoked potentials in awake and anesthetized patients].

Late auditory evoked potentials (50-500 msec latency) can be evoked by tonal stimuli but their instability prevents their use in many clinical situations. In contrast, the early responses (up to 10 msec) are stable, regardless of sleep or sedation, but they can only be evoked by transient, non-tonal stimuli. Therefore neither type may be used for an evaluation of frequency thresholds. The middle latency responses represent a compromise: first, they can be evoked by tonal stimuli of the tone-pip type and, second, they are relatively stable. For these reasons the authors have carried out a general study on the middle latency responses in subjects with normal hearing, in patients with impaired hearing and in patients under a variety of surgical anesthesia. The middle latency response evoked by clicks and tone-pips (4 sines of 500, 1000, 2000 and 4000 Hz) have a series of characteristic waves named, according to their latency, A(V), B(No), C(Po), D(Na), E(Pa). The threshold of visual detection for these potentials is situated near that of the psycho-acoustic threshold (0-20 dB). The authors point out the clinical utilization of the middle latency response especially in cases in which one desires an objective evaluation of the auditory threshold in the lower frequency range. It is important to know that the middle latency response remains present using some types of anesthesia (Ketalar, ataralgesy), disappears partially with neuroleptanesthesia and completely with inhalation anesthesia (fluothane, halothane).

Adult↗
PubMed1984

Psychometric intelligence correlates with interindividual different rates of lipid peroxidation.

The review outlines a theory concerning the neurochemical basis of interindividual differences in human intelligence. From the work of Lehrl and Frank it can be concluded that Spearman's general factor of intelligence is a phenomenon of short-term memory capacity, i.e. a phenomenon of reversible short-term changes in synaptic membrane permeability. The empirical correlations between glutathione peroxidase activity, a genetically polymorphous enzyme, and IQ, and between the relative lipofuscin content of the brain and the ontogenetic development of fluid intelligence, have the background that peroxidation of phospholipids and its cleavage products are the regulating factors of membrane permeability. Furthermore, the glutathione status plays via lipid peroxidation, activating adenylate cyclase and inhibiting the sodium pump and acetylcholinesterase, an essential role in the regulation of energy supply and reducing power of cortical cells. In inbred strains of mice inherited learning speed, serum peroxide levels, and the parameters of the acetylcholine system are closely correlated.

Animals↗
PubMed1983

Chronic infection with cutaneous herpes simplex in a patient with systemic lupus erythematosus.

A 68-year-old black woman with systemic lupus erythematosus being managed by systemic corticosteroids developed large ulcerated lesions in a dermatomal distribution on the flank and abdomen. Subsequently, large ulcers developed progressively in the perianal region, the buttocks, the perivaginal region, and the thighs. The clinical diagnosis was vasculitis of systemic lupus erythematosus. Biopsy from the margin of an ulcer showed changes in the epidermis that are specific for infections by herpesvirus. Electron microscopy revealed viral particles of herpesvirus. Cultures from the perianal lesions grew Herpesvirus hominis. This is the first report to our knowledge of "chronic cutaneous herpes infection" in a patient with systemic lupus erythematosus.

Aged↗
PubMed1983

Heparin-stimulated modification of C1-inhibitor by subcomponent C1s of human complement.

C1-inhibitor and C1s form a very stable complex which migrates with an apparent molecular mass of 180 kDa in dodecyl sulfate gel electrophoresis. A small fraction of the inhibitor (100 kDa) was found to be converted to a large (95 kDa) and a small (2 to 5 kDa) fragment during this reaction. It is concluded that C1-inhibitor is modified by C1s in a similar way as are the related plasma inhibitors alpha 1-proteinase inhibitor, antithrombin III and antiplasmin by their specific proteinases. The fraction of modified C1-inhibitor increased when heparin was present during complex formation. This reaction was complete after 15 s and is comparable with the fast heparin induced formation of modified antithrombin III. Treatment with hydroxylamine led to a complete dissociation of the inhibitor-enzyme complex by dodecyl sulfate. The large inhibitor fragment (and not unmodified inhibitor as reported by other authors) was released.

Complement Activating Enzymes↗