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Biomedical subjects

M Weiss

Publications and source records attributed to M Weiss.

At least 595 records · Page 33Linked to original sources
PubMed1986

Products of two common alleles at the locus for human placental alkaline phosphatase differ by seven amino acids.

Amino-terminal amino acid sequences (42 residues) were determined for the products of the three common alleles at the human placental alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] gene locus. The sequences differ at position 3, which is proline in types 1 and 2 but is leucine in type 3. cDNA libraries were constructed in phage lambda gt11 and used to isolate clones covering the coding regions of types 1 and 3 cDNAs. Comparison of the deduced amino acid sequences of the types 1 and 3 proteins showed 7 differences out of 513 amino acids, each due to a single base substitution. cDNA sequence comparisons showed three silent substitutions in the coding regions and three base differences in the greater than 1 kilobase pairs of 3' untranslated sequences.

Alkaline Phosphatase↗
PubMed1986

The peplomers of Berne virus.

Using [3H]glucosamine and [3H]mannose labels, two virus-specific glycosylated polypeptide species with Mr values of about 200,000 (200K) and in the 75K to 100K range, respectively, were recognized in Berne virus-infected embryonic mule skin cells. In purified virions only the latter glycoprotein occurred. Concanavalin A was bound to the virion as evidenced by reduction in infectivity. Analyses using SDS-PAGE, blotting and glycoprotein identification with concanavalin A and horseradish peroxidase showed coincidence of the virion glycoprotein signals with the maximum infectivity and haemagglutinating activity in an isokinetic sucrose gradient. Polyclonal rabbit immune serum and a neutralizing and haemagglutination-inhibiting monoclonal antibody raised against Berne virus recognized both the 75K to 100K and the '200K' glycoproteins. Using tunicamycin, a concentration-dependent inhibition of infectivity was noted; however, non-infectious particles containing the two major polypeptides (20K and 22K) were released from the cells in small quantities. The glycoproteins were absent from cytoplasmic extracts and a novel polypeptide of about 150K was identified instead. Translation of poly(A)-selected intracellular RNA from infected cells in a rabbit reticulocyte cell-free system also resulted in the appearance of a new high Mr polypeptide (about 170K). Using pulse-chase labelling and radioimmunoprecipitation, suggestive evidence for a precursor-product relationship between the intracellular '200K' and the virion glycoproteins has been obtained. These experiments identify the N-glycosylated proteins in the 75K to 100K range as constituents of the peplomeric envelope projection of Berne virus; they probably arise by post-translational processing of a 150K to 170K precursor molecule involving glycosylation and subsequent cleavage.

Antibodies, Viral↗
PubMed1986

The haemagglutinating activity of Berne virus.

Berne virus possesses haemagglutinating activity which is inhibited by antisera that neutralize the infectivity of the virus. In decreasing order, human, rabbit and guinea-pig erythrocytes were agglutinated whereas agglutination was not observed with rat, goose, chicken or horse red blood cells. This pattern is different from that seen with the closely related Breda virus of cattle. Haemagglutinin was found to co-sediment with viral infectivity in sucrose density gradients. Transmission electron microscopy showed that intact virus particles form bridges between adjacent erythrocytes. The viral envelope was seen at a distance from the erythrocyte surface suggesting that the peplomers possess haemagglutinating activity. Haemagglutination was decreased in the presence of fetuin and gangliosides and also by pretreatment of the erythrocytes with periodate, suggesting that the virus binds to glycoproteins and/or glycolipids on the erythrocyte surface.

Animals↗
PubMed1986

Morphogenesis of Berne virus (proposed family Toroviridae).

In equine dermis cells infected with Berne virus particles were first detected 10 h after infection. Virions were encountered in all parts of the Golgi system and, infrequently, in the rough endoplasmic reticulum. A unique form of budding of preassembled rigid tubular nucleocapsids was demonstrated. Masses of tubular nucleocapsids of a lesser diameter and electron density were prominent in the cytoplasm and the nucleus of infected cells. Within the Golgi system and cytoplasmic cisternae virions appeared as straight or slightly curved rods. Extremely long, aberrant virions (250 nm) were occasionally seen. The proper torovirion morphology was observed in extracellular particles and in vacuoles near the cell surface.

Animals↗
PubMed1986

Insulin-like growth factor I regulates growth hormone secretion and messenger ribonucleic acid levels in human pituitary tumor cells.

GH secretion and mRNA levels were measured in cultured human GH adenoma cells incubated in serum-free medium for up to 48 h. A human recombinant insulin-like growth factor I (IGF-I) analog, Thr-59-IGF-I (6.5 nM), inhibited basal GH secretion by up to 60% in tumor cell cultures. The 30-50% stimulation of GH secretion by GH-releasing hormone (GHRH) was prevented by simultaneous exposure of the cells to IGF-I (6.5 nM). Gel electrophoresis of total RNA derived from GH cell adenoma tissue, followed by transfer and hybridization with 32P-labeled human GH cDNA, revealed a distinct mRNA species of about 1.0 kilobases. Using cytoplasmic dot blot hybridization, IGF-I inhibited the levels of human GH mRNA sequences in these cells and also prevented the GHRH-induced stimulation of GH mRNA. A monoclonal antibody to the type I IGF-I receptor (alpha IR3) prevented the inhibitory effects of IGF-I on basal and GHRH-stimulated GH secretion. This antibody also prevented the IGF-I-induced suppression of GH mRNA sequences. PRL secretion in these cells was not altered by IGF-I. Furthermore, relative levels of beta-actin mRNA were unaltered by IGF-I. Thus, IGF-I suppresses basal and GHRH-stimulated GH secretion and GH mRNA levels in pituitary adenoma cells, indicating that IGF-I acts selectively on the somatotroph to directly regulate GH gene expression.

Adenoma↗
PubMed1986

[Diagnosis of cellular respiratory arrest by NADH laser fluorimetry. Applications in heart surgery and in experimental pharmacology].

The continuous measurement of intratissular NADH concentration allows early detection of cellular respiration arrest during clinical situations, i.e. allows a non-destructive, in situ, continuous measurement of ATP formation. This detection enables the physician or surgeon to intervene during a phase of cellular respiration arrest, before structural cellular alterations occur, thereby preventing potential tissular necrosis. The method has now been validated in experimental cardiac surgery for the monitoring of myocardial preservation techniques during cardiopulmonary by-pass, and in cardiac pharmacology, for analysis of drugs' effects on myocardial energetic metabolism. Its industrial development is currently under way. Preliminary investigation strongly suggests the vast potential of this diagnostic method in both clinical and experimental fields.

Adenosine Triphosphate↗
PubMed1986

Are serum levels and cardiac effects of digoxin influenced by indometacin?

Intraindividually compared to placebo, the possible influence of an oral pretreatment with the cyclooxygenase inhibitor indometacin on serum concentrations and cardiac effects of digoxin, administered by a controlled intravenous infusion, was evaluated in 6 healthy male humans. A significant pharmacokinetic or pharmacodynamic interaction between both drugs could not be found. Indometacin only tended to elevate serum digoxin levels, to strengthen the digoxin induced decrease in the electrocardiogram parameters heart rate and QTc time as well as to reduce the positive inotropic action of digoxin measured by systolic time intervals and PTQ index.

Adult↗
PubMed1985

Digital quantification eliminates intraobserver and interobserver variability in the evaluation of coronary artery stenosis.

A leading problem with subjective interpretation of coronary angiography is high intraobserver and interobserver variability. Four experienced angiographers independently determined percent diameter narrowing of 36 stenoses using 3 methods: by subjective analysis of single-frame cine film images (film), by subjective analysis of digitized nonenhanced single-frame images (digital), and by using a semiautomated digital caliper quantification system (Corona). The reproducibility of interpretations was assessed by comparison of estimated intraclass correlation coefficients. Digital and Corona readings correlated well with subjective interpretation of film (r greater than 0.85 for both). In contrast to Corona, the angiographers systematically overestimated the magnitude of stenoses in the intermediate (50 to 75%) range. Corona markedly improved intraobserver (p less than 0.005) and interobserver (p less than 0.001) reproducibility. Corona less frequently misclassified individual observations than did film when categories of less than 50%, 50 to 75% and more than 75% diameter stenosis were used (3.7% vs 31.5%, p less than 0.001). Our results suggest that digitization of a coronary angiogram in a 512 X 512 matrix has no significant adverse effects on the perception and quantification of stenosis by angiographers. Additionally, automatic measurement of coronary stenosis has 2 major advantages: It is accurate compared with a group of experienced angiographers and for the practical purpose of clinical decision-making, it eliminates intraobserver and interobserver variability.

Angiography↗
PubMed1985

Theorems on log-convex disposition curves in drug and tracer kinetics.

Conventionally, analysis of the dynamic behaviour of substances in the whole organism is based on the multiexponential paradigm (compartmental model). Alternatively the use of power functions has been proposed. In this paper a unified view is developed investigating the implications of observed log-convexity of disposition (clearance) curves. Using a non-compartmental approach it is proved that the disposition residence time distribution corresponding to a log-convex impulse response (blood concentration-time curve) belongs to the DFR (decreasing failure rate) class, implying that (1) the disposition curve has an exponential tail and (2) the relative dispersion of residence times is greater than or equal to one. This class of disposition curves includes multiexponential and power functions as special cases. In terms of the underlying biophysical principles the DFR property is discussed as a consequence of a dominant role of passive distribution processes of particles in the organism. The paper also deals with the corresponding properties of a recirculatory model using renewal theoretic concepts.

Diagnostic Uses of Chemicals↗
PubMed1985

Spectral and catalytical properties of the sarcoplasmic reticulum Ca-ATPase labeled with N-cyclohexyl-N'-(4-dimethylamino-1-naphthyl)-carbodiimide.

N-Cyclohexyl-N'-(dimethylamino)-carbodiimide (NCD-4) labels three sites in the sarcoplasmic reticulum Ca-ATPase which can be resolved by their spectral properties and by their effects on the catalytical activity of the enzyme. One site is not protectable by Ca2+ ions or by dicyclohexylcarbodiimide and is not essential for catalytical activity. Two Ca2+-protectable sites, whose modification leads to a biphasic inhibition of Ca-ATPase activity, have fluorescence emission maxima at 407 nm and 425 nm. The Ca-ATPase modified by NCD-4 hydrolyses ATP but does not translocate Ca2+ nor does it undergo the conformational changes associated with Ca2+ binding in the native enzyme. High concentrations of Ca2+ induce slow biphasic fluorescence quenching in the Ca-ATPase labeled selectively at the 407-nm site but the signals are largely abolished by modification of the 425-nm site. Both vanadate ions and ATP reverse this Ca2+-induced fluorescence quenching. It is proposed that NCD-4 labels the two high-affinity Ca2+-binding sites of the Sarcoplasmic reticulum Ca-ATPase and that the conformational changes in the modified enzyme may reflect interactions between the two sites.

Animals↗