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Biomedical subjects

R Bloch

Publications and source records attributed to R Bloch.

At least 91 records · Page 5Linked to original sources
PubMed1977

Sugar-specific antibodies reactive towards cell-surface carbohydrates.

Antibodies generated against sugar-azoproteins have been purified by affinity chromatography using elution with monosaccharide. They have high specificity for monosaccharide and they react with terminal, non-reducing sugars on the surfaces of human erythrocytes. Some of them, either native or as Fab fragments, inhibit mitogenic stimulation of lymphocytes by concanavalin A.

Animals↗
PubMed1977

Relationship between the ventromedullary clonidine-sensitive area and the posterior hypothalamus.

The connections between the areas 'S' which have been previously described as the ventromedullary sites of the action of clonidine and the posterior hypothalamus have been investigated. Superficial electrocoagulation of the left area 'S' suppresses the pressor response to electrical stimulation of the homolateral part of the posterior hypothalamus. Although such medullary lesions cause a significant reduction of the mean arterial pressure, the contralateral hypothalamic stimulation can still increase blood pressure. Clonidine it self applied topically (8 micrograms/kg) to the ventral face of the brain stem decreases the blood pressure response to liminal hypothalamic stimulation. It is concluded that efferent pathways, which are involved in vasomotor regulation, originate in the posterior hypothalamus and run through the ventrolateral part of the brain stem. The mechanism of the blocking effect of clonidine on these pathways is discussed.

Animals↗
PubMed1977

[Clinical and biological manifestations following the interruption of prolonged treatment with clonidine].

In 7 out of 14 patients there were marked subjective symptoms following the interruption of prolonged treatment with clonidine. A significant increase in blood pressure, systolic and diastolic, heart rate and urinary catecholamine excretion was seen in the majority of cases. The clinical and biological manifestations would appear to reflect a phenomenon of derepression of sympathetic activity: the increase in urinary catecholamines is the biological result. The findings are of practical importance since they indicate that the interruption of anti-hypertensive therapy with clonidine must be under taken with caution, i.e. progressively.

Adult↗
PubMed1977

[A modified guaiac test for the early detection of tumors of the intestinal tract (author's transl)].

Of 1400 patients who were submitted to the Haemoccult test, 46 showed a postive result. Among other things there were 29 polyps, of which 3 already showed a focal carcinoma, and 5 carcinomata of the large intestine and 3 gastric carcinomata were also diagnosed. Over 70% of the tumor hosts had observed bleeding per anum at some time. In order to detect the number of false nagative results, patients were investigated in the same way even when the Haemoccult test had been negative three times. In this way 55 polyps were found as well as 7 partly advanced carcinomata of the large intestine. 35% of the Haemoccult-negative patients stated bleeding per anum in their history. The number of false negative findings must be considerably higher than previously estimated.

Colonic Neoplasms↗
PubMed1977

Pharmacokinetics of cefaclor in normal subjects and patients with chronic renal failure.

We studied the pharmacokinetics of cefaclor, a new cephalosporin antibiotic, in normal subjects and subjects with chronic renal failure. Cefaclor was largely, but not entirely, eliminated by the kidneys. The cefaclor half-life in normal subjects was 40 to 60 min; in subjects with essentially no renal function, it increased to 3 h. In normal subjects, 50 to 70% of a 250-mg dose was excreted in the urine within 8 h. The linear relationship between the elimination constant and creatinine clearance allowed the construction of a useful dosage modification nomogram.

Animals↗
PubMed1977

[Variations in the effect of clonidine on arterial pressure in rats in the presence of various anesthetics].

The central hypotensive agent, clonidine (30 microgram/kg i.v.) has been injected in normotensive rats anesthetized with various agents. This dose of clonidine elicits usually a biphasic blood pressure response, i.e. a transient increase due to peripheral vasoconstriction, followed by a long lasting decrease. This has been observed in the animals anesthetized with pentobarbitone as well as with urethane. The hypotensive effect is abolished during chloralose, ketamine or Alfatésine anesthesia. These data emphasize that some anesthetics mays particularly modify the effects of centrally acting cardiovascular drugs.

Alfaxalone Alfadolone Mixture↗
PubMed1977

[Normal nutrition--malnutrition during malassimilation?].

Intestinal resorption can be disturbed in its intraluminal, intracellular or postcellular phase. Any such dysfunction may lead to an isolated or global malabsorption syndrome. An exact elucidation of the underlying pathophysiology is a prerequisite for a rational diet prescription. Only when this is completed, the diet can be adapted in a quantitative and qualitative sense to the residual intact function of the diseased digestion or absorption organ. The dietetic measures in an isolated or global malabsorption syndrome have been discussed.

Amino Acids↗
PubMed1976

Purification and characterization of two lectins from Caragana arborescens seeds.

A glycoprotein fraction with hemagglutinating activity was purified by affinity chromatography from seeds of the pea tree, Caragana arborescens. Subsequent fractionation resolved two components, which could be separated on a preparative scale using different affinity matrices. The major component binds to N-acetylgalactosamine coupled to Sepharose 4B. It is a glycoprotein with high hemagglutinating activity. It is composed of two types of polypeptides, present in nonstoichiometric amounts, with apparent molecular weights near 30,000. In the native molecule, the subunits are cross-linked by disulfide bonds to form dimers, which in turn appear to be in rapid equilibrium with tetramers. The minor component binds to underivatized Sepharose 4B. It too, is a glycoprotein but has low hemagglutinating activity. It is composed of three types of polypeptides which, although they have apparent molecular weights near 30,000 are distinguished from the subunits of the major hemagglutinin by a number of physical and chemical properties. The native molecule is dimeric, with a mass of 60,000 daltons. The major component has high affinity (K = 0.1 mM) for the haptenic sugar, N-acetylgalactosamine, but will also bind D-galactose. Neither lectin has ABO blood group specificity, nor are they transformed mouse fibroblasts to the same extent.

Acetylgalactosamine↗
PubMed1976

A mathematical model of cerebrospinal fluid dynamics.

The ability to solve systems of simultaneous non-linear differential equations by a combination of analytical and computational techniques has encouraged the development of valid mathematical models of biological phenomena. The dynamics of the cerebrospinal fluid (CSF) system has been the subject of closer scrutiny in recent years since the recognition of symptomatic low-pressure hydrocephalic states in man. A mathematical model has been derived from 7 assumptions: (1) That the brain is a spherical shell. (2) That CSF is secreted at a constant rate. (3) That CSF absorption is linearly dependent on pressure. (4) That flow between the CSF compartments is proportional to the pressure difference. (5) That Laplace's Law holds for the visco-elastic properties of the brain. (6) That there is compliance in the spinal compartment of the CSF system. (7) That vascular pulsations in the cranial and spinal compartments are capacitatively coupled. Using known data (and estimates of as yet unknown values) for the several parameters, the validity of the model has been successfully tested against 3 clinical conditions. This model extends our understanding of derangements of CSF dynamics and suggest where further research may yield data at present lacking.

Cerebrospinal Fluid↗
PubMed1975

Functional, biochemical and morphological alterations in the intestines of rats with an experimental blind-loop syndrome.

In rat self-filling blind loops and in the contiguous regions of the intestinal tract, considerable functional impairment, accompanied by pronounced morphological transformations of the mucosa, has been observed. The histological alterations consist of mucosal hypertrophy and a reduction in the villus height: crypt length ratio, which is indicative of a hyper-regenerative change. Various enzyme activities of the epithelial cells are reduced and the absorption otinal juices is greatly altered in favour of the free acids. Two mec,anisms have 0een dicids, or meta0olites from bacterial degradation, on the absorptive epithelium; 2. Reduced cellular maturity in response to the effect of bile acids and/or bacteria on the lifespan of the cells.

Animals↗