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Biomedical subjects

S Behr

Publications and source records attributed to S Behr.

12 recordsLinked to original sources
PubMed2003

Assessment of a pyrogallol red technique for total protein measurement in the cerebrospinal fluid of dogs.

The measurement of protein concentration in the cerebrospinal fluid is a basic analytical method in neurology. In this study, a pyrogallol red technique using a human albumin calibrator previously validated in human medicine was tested for canine samples, and the results were compared with those obtained using urine test strips. Pyrogallol red significantly (P<0.05) but moderately underestimated purified dog albumin and globulins. The imprecision of the technique was low: intra- and between-series coefficients of variation were 1.6 and 4.3 per cent at protein concentrations of about 0.3 g/litre. Over 49 samples, there was good agreement between the pyrogallol red and test strip results (r=0.63), especially for low and high protein concentrations, but misclassifications were observed with '+' test strip readings.

Animals↗
PubMed2000

Low levels of viscous hydrocolloids lower plasma cholesterol in rats primarily by impairing cholesterol absorption.

Hydrocolloids have been proposed as cholesterol-lowering agents, but their viscosity limits their use in human nutrition. A low level (1 %) of hydrocolloids (guar gum, (GG); xanthan gum, (XG); and konjac mannan) was investigated in rats fed 0.2 g/100 g cholesterol diets. Food intake and body weight gain were not altered by the diets. Bile flow and cholesterol bile flux were not modified by diet, whereas the bile acid flux was greater in rats fed hydrocolloid diets. The cecal pool of bile acids was greater than control rats only in rats fed the XG diet (+71%, P<0.001). The fecal excretion of neutral sterols was stimulated in rats fed the hydrocolloid diets; cholesterol apparent digestibility (60% in controls) was reduced to 30-36% in rats fed hydrocolloids. Bile acid fecal excretion was not altered by diet treatment. As a result, apparent steroid balance was about +40 micromol/d in controls and only +10 to +20 micromol/d in rats fed hydrocolloids. Both plasma cholesterol and triglycerides were significantly lower than controls in rats fed XG, but only cholesterol was lower in rats fed the GG diet. These effects were essentially found in the d <1.040 kg/L fraction. Liver cholesterol content was significantly lower than in controls in rats fed the GG or XG diets. Liver HMG CoA reductase was not affected by the hydrocolloid diets. In conclusion, a low percentage of viscous hydrocolloids lowers plasma cholesterol in cholesterol-fed rats. Inhibition of intestinal cholesterol absorption may be the primary mechanism.

Animals↗
PubMed1999

A fully automated multicapillary electrophoresis device for DNA analysis.

We describe the construction and performance of a fully automated multicapillary electrophoresis system for the analysis of fluorescently labeled biomolecules. A special detection system allows the simultaneous spectral analysis of all 96 capillaries. The main features are true parallel detection without any moving parts, high robustness, and full compatibility to existing protocols. The device can process up to 40 microtiter plates (96 and 384 well) without human interference, which means up to 15,000 samples before it has to be reloaded.

Automation↗
PubMed1997

Fermentable carbohydrate exerts a urea-lowering effect in normal and nephrectomized rats.

The influence of nondigestible carbohydrate on intestinal fermentations and on the route of nitrogen excretion has been investigated in normal rats and in unilaterally nephrectomized rats. Rats were adapted to 10% casein diets, either fiber free or containing different levels of two fermentable carbohydrates, inulin or crude potato starch. Ingestion of fermentable carbohydrate led to a considerable enlargement of the cecum because of hypertrophy of the cecal wall and an increase in cecal contents. Cecal digesta contained elevated concentrations of short-chain fatty acids, resulting in acidic pH. Diets containing fermentable carbohydrate enhanced fecal nitrogen excretion, which was more than doubled at the highest level of inulin or potato starch. In parallel, urinary nitrogen excretion was significantly decreased by fermentable carbohydrate. Although these changes were similar in all animals, there were quantitative differences in the response of nephrectomized animals to fermentable carbohydrate. In nephrectomized rats, plasma urea concentrations were more than 2.5 times higher than in normal rats (5.8 mM compared with 2.2 mM). Plasma urea concentrations were reduced by approximately 50% when normal rats were fed diets containing 7.5-15% inulin or 10-20% resistant starch. In nephrectomized animals fed the highest level of fermentable carbohydrate, plasma urea concentrations were also significantly decreased, but only by 30%. In nephrectomized rats, the concentration of nitrogen cycling in the cecum was greater (urea nitrogen transfer into the cecum was 50-60% greater and ammonia flux from the cecal lumen to the blood was two times higher than in normal rats), but fecal nitrogen excretion was equivalent in normal and nephrectomized animals. When expressed as a percentage of total nitrogen excretion, fecal nitrogen excretion was <20% in animals fed fiber-free diets, compared with 45-50% in normal animals and 40% in nephrectomized animals fed fermentable carbohydrate.

Ammonia↗
PubMed1995

Engaging CD19 or target of an antiproliferative antibody 1 on human B lymphocytes induces binding of B cells to the interfollicular stroma of human tonsils via integrin alpha 4/beta 1 and fibronectin.

Adhesion of B lymphocytes within the different compartments of secondary lymphoid organs is essential for the function of the humoral immune response. It is not currently known how the temporary immobilization of B cells in distinct areas of this complex microenvironment is regulated. The present study aimed at defining B cell antigens that initiate binding of B cells to human tonsil sections in situ. Engaging the B cell antigens CD19 and target of an antiproliferative antibody 1 (TAPA-1) with monoclonal antibodies induced adhesion of these B cells to the interfollicular stroma. This binding occurred through the integrin alpha 4 beta 1 on the B cell surface and via the extracellular matrix protein fibronectin expressed in the interfollicular compartment of the tonsil. Signaling through either antigen, CD19 or TAPA-1, depended on tyrosine kinases. Binding induced by engaging CD19 required an intact cytoskeleton, whereas TAPA-1-transmitted adhesion did not. We suggest that CD19 and TAPA-1 have a novel and unique function by regulating an alpha 4 beta 1/fibronectin-mediated binding of B cells to the interfollicular stroma of lymphoid tissues.

Antibodies, Monoclonal↗
PubMed1995

Symptomatic mumps virus reinfections.

Although natural mumps virus infection is believed to induce lifelong immunity, our laboratory was confronted with 82 patients who developed mumps-evoking lesions but exhibited serological evidence of a booster immune response, namely a rise or a high titer of virus-specific IgG, without IgM. In order to provide arguments favoring the existence of recurrent mumps attacks, the age, symptomatology, and humoral response of these patients (group 1) were compared to that of 82 randomly selected true primary infected patients (group 2), 10 parainfluenza virus-infected patients (group 3), and 20 noninfected mumps-immune subjects (group 4). Enzyme-linked immunosorbent assay (ELISA) procedures with different viral antigenic preparations were used for determination of specific IgM, IgA, IgG, IgG subclasses, and IgG avidity. The patients of group 1, older than those of group 2 (28 vs. 10 years, P < 0.0001), presented a significantly less severe and less typical symptomatology. Against the whole virus they exhibited IgG of higher avidity (P < 0.001), a lower prevalence and titer of IgA (10 vs. 68%, P < 0.0001 and 278 vs. 5,009, P < 0.001, respectively). Values obtained for IgG 1, 2, and 3 were significantly different between the two groups. Prevalence and absorbance of nucleocapsid-directed IgG 3 were significantly lower in group 1 (27 vs. 46%, P < 0.01 and 0.444 vs. 0.869, P < 0.01, respectively). A significant discrepancy also allowed patients from group 1 to be distinguished from those of groups 3 and 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Fermentable fibers or oligosaccharides reduce urinary nitrogen excretion by increasing urea disposal in the rat cecum.

The availability of fermentable carbohydrates could influence the digestive degradation and disposal of blood urea. The effects of a poorly fermented cellulosic oat fiber, a soluble fermentable fiber (gum arabic) or one of two oligosaccharides (fructooligosaccharide or xylooligosaccharide) on nitrogen excretion were compared with a wheat starch-based control diet in male Wistar rats. The fibers and oligosaccharides were added to the semipurified diets at 7.5 g/100 g in place of wheat starch. The diets contained 13 g casein/100 g. Oat fiber did not cause an enlargement of the cecum. In contrast, gum arabic and the oligosaccharides elicited a 35-60% enlargement of the cecal wall and a 2 to 2.6-fold mean increase in the cecal pool of short chain fatty acids. Compared with rats fed the oat fiber-based diet, urea flux from blood to cecum was nearly 50% greater and more than 120% greater in those fed the gum arabic and oligosaccharide diets, respectively. In those groups, net nitrogen retention in the cecum more than doubled (nitrogen retention was calculated as the difference between net urea nitrogen flux into the cecum and ammonia nitrogen reabsorption). As a percentage of total excreted nitrogen, fecal nitrogen was 20% in the oat fiber group and 27-29% in the gum arabic and oligosaccharide groups, compared with only 10% in fiber-free controls. Results indicate that under these dietary conditions, the addition of oligosaccharides to the diet induced a 20 to 30% decrease in blood urea and renal and renal nitrogen excretion relative to the control, indicating a potential for oligosaccharide diet therapy in chronic renal disease.

Animals↗
PubMed1995

The effect of esmolol given during cardiopulmonary bypass.

beta-Adrenergic antagonism decreases the size of myocardial infarction and provides myocardial protection during hypothermic arrest for cardiac surgery. However, concern regarding the negative inotropic and chronotropic effects of beta-adrenergic antagonism persisting after cardiopulmonary bypass (CPB) has impeded the use of esmolol for this purpose during cardiac surgery. This is a randomized, double-blind prospective study of the effects of esmolol infused during CPB and the effects of hypothermic CPB on esmolol. Patients scheduled for CPB were randomized to receive intravenous esmolol (300.micrograms.kg-1.min-1 during CPB after a bolus of 2 mg/kg prior to CPB) or placebo. Infusion was stopped at 10 min after release of aortic cross-clamp. Hemodynamics were measured, as well as serum esmolol, catecholamines, lactate, and potassium. Postoperative variables measured included electrocardiographic changes, creatine kinase (CK)-MB fractions, post-CPB dysrhythmias and drugs, hospitalization time and cost, and mortality. Esmolol was administered to 16 patients and placebo to 14. Esmolol levels reached a high of 10.5 +/- 0.9 micrograms/mL during CPB, but decreased to 0.1 +/- 0.02 microgram/mL within 30 min after stopping infusion. Cardiac indices (cardiac index, stroke volume index, left cardiac work index, left ventricular stroke work index, right cardiac work index, and right ventricular stroke work index) were higher in the esmolol group for the first hour post-CPB (P < 0.05). Systemic arterial lactate and coronary sinus lactate were lower in the esmolol group after CPB (P < 0.05), but myocardial lactate extraction was not significantly different between groups. After CPB, hemoglobin was lower in the esmolol group (P < 0.05) due to longer CPB and aortic cross-clamp time (P < 0.05), but oxygen consumption was less than in the control group (P < 0.05). Post-CPB serum potassium was higher in the esmolol group (P < 0.05). Results are confounded by more chronically beta-adrenergically blocked patients randomized to the esmolol group (P < 0.05). Esmolol infused during CPB in this series of patients was associated with high concentrations during CPB but did not result in any adverse clinical effects after CPB.

Adrenergic beta-Antagonists↗
PubMed1991

Adsorption/desorption of human serum albumin on hydroxyapatite: a critical analysis of the Langmuir model.

We studied the adsorption of human albumin onto synthetic hydroxyapatite, using a radiotracer technique and a special flow cell. Adsorption was studied under various conditions corresponding to different thermodynamic paths. It appears that (i) as is the usual case, the isotherms obtained within a short time range (a few hours) do not correspond to a true equilibrium situation; (ii) when the adsorption process is followed for longer times, which is necessary at low bulk concentrations, one always reaches the plateau surface adsorption; (iii) this plateau value is independent of the "history" of the adsorption process and corresponds well to the jamming limit predicted by the random sequential adsorption model; and (iv) surface denaturation, leading to enhanced surface binding and thus decreasing desorption constants, is the important phenomenon that can partly and qualitatively explain our observations. Its time dependence, however, remains to be clarified.

Adsorption↗
PubMed1989

Desorption and exchange properties of adsorbed albumin on apatite. Influence of long-term interfacial residence times.

A technique using 125I-labeled proteins was employed to study static adsorption properties and slow exchange and desorption processes of human albumin in contact with synthetic hydroxyapatite beads. With the aid of a thermostated "minicolumn," the adsorption isotherm was obtained during a so-called multiadsorption process, and could be described by a Langmuir adsorption model (K = 1.10 x 10(10) cm3.mol-1). All kinetic desorption and exchange experiments could be fitted by a simple exponential function of time. No influence of long-term interfacial residence times on characteristic relaxation times or percentage of desorbed or exchanged proteins could be detected in the present system. On the other hand, as compared to the low surface coverage domain, the small percentage of desorbable and high percentage of exchangeable molecules in the adsorption plateau domain was attributed to a bimolecular exchange process.

Adsorption↗
PubMed1989

A modified Limulus amebocyte lysate test with increased sensitivity for detection of bacterial endotoxin.

We have developed a simple modification of the chromogenic Limulus amebocyte lysate test that increases the sensitivity for the detection of bacterial endotoxins. In this assay, free paranitroaniline, cleaved from synthetic chromogenic substrates by proteases that were generated by Limulus lysate after incubation with endotoxin, was then derived. Derivation was with p-dimethylaminocinnamaldehyde in the presence of strong acid, forming a stable Schiff base end product with much greater molar absorbancy than the parent chromogen. Conditions (times and temperatures of incubations, concentrations of reagents) for the augmented chromogenic procedure were optimized. A ten-fold or greater increase in sensitivity for bacterial endotoxin was obtained with the modified assay as compared with the standard chromogenic Limulus test, with unequivocal detection of endotoxin concentrations of less than 100 pg/ml. The greater sensitivity of this modified Limulus test increases its usefulness for a wide range of research applications and clinical investigations.

Colorimetry↗