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Biomedical subjects

B Horowitz

Publications and source records attributed to B Horowitz.

At least 163 records · Page 9Linked to original sources
PubMed1978

Arthrographic demonstration of pigmented villonodular synovitis of the knee.

Arthrography of the knee is most frequently used for diagnosis of conditions affecting the cartilage and menisci. In a 40-year-old man with pigmented villonodular synovitis, arthrography demonstrated a characteristic pattern of multiple filling defects. Arthrography may prove to be as useful for diagnosis of synovial lesions as for other intraarticular lesions.

Adult↗
PubMed1977

Development of hemagglutination assays I. Attachment of anti-HBs antibody to stabilized erythrocytes.

Conditions favoring the coupling of antibody to human erythrocytes stabilized by a variety of reagents were studied with the use of antibody to hepatitis B surface antigen. Functional anti-HBs bound to erythrocytes was measured by radioimmune assay using 125 I-HBsAg. The attachment of anti-HBs to aldehyde-stabilized cells is favored by low pH and low ionic strength. The extent of antibody binding is both concentration and time dependent. Development of spontaneous agglutination of the coated erythrocytes occurs with the attachment of increasing quantities of anti-HBs. Although antibody was rapidly taken up by aldehyde-stabilized erythrocytes, it was initially readily dissociable, but after longer exposure became firmly bound. Experiments pertaining to the chemical nature of the more stable antibody-erythrocyte complex gave results consistent with covalent bond formation, though rigorous proof was not developed.

Antibodies, Viral↗
PubMed1977

Development of hemagglutination assays II. Enhancement in the sensitivity of an RPHA test for HBsAg.

Studies were undertaken to enhance the sensitivity of a previously developed RPHA test for HBsAg. A net increase in sensitivity of approximately 3-fold was achieved by modifying the elution procedure used to purify chimpanzee anti-HBs by affinity chromatography. A further 3- or 4-fold sensitivity increase was achieved by increasing the volume of specimen tested. A concomitant increase in nonspecific agglutination usually observed with increased specimen size was avoided by incubating the reaction mixture at 37 or 45 degrees C. Evaluation of the test in detection of HBsAg in blood obtained from volunteer donors indicates that the materials produced at the New York Blood Center using the modified test protocol compare favorably with a commercial RPHA test. Modifications which did not contribute toward enhancing sensitivity are also reported.

Hemagglutination Tests↗
PubMed1976

Congenital annular constrictions due to amniotic bands.

Amniotic bands which become involved with fetal parts, especially the extremities, are produced by rupture of the amnion during pregnancy with the consequent union of the extra-embryonic mesoderm in fibrous strings. An infant with the amniotic band syndrome, in whom an annular constriction of the left leg and right hand was found, is described. He was treated successfully by multiple Z-plasties and a plaster cast to correct the clubfoot. The oedema of the leg persisted for 5 weeks and then subsided completely. The role of amniotic abnormalities in the production of congenital malformations is reappraised. The microscopic and histological investigation of the placenta and membranes should accompany every case of fetal malformation in abortuses, stillbirths, and affected newborn.

Abnormalities, Multiple↗
PubMed1975

A new method for mutant selection in Saccharomyces cerevisiae.

A new method for the selection of auxotrophic, antibiotic- and temperature=sensitivemutants in Saccharomyces cerevisiae is reported. The technique is based upon the observation that certain fatty acid auxotrophs of yeast die when deprived of fatty acid only under conditions supporting growth. When macromolecular synthesis is blocked, the fattyacid-starved cells survive. By appropriate manipulation of a fatty acid-requiring strain enrichment as great as 75-fold was achieved for certain classes of auxotrophic mutants. An enrichment of approximately 100-fold is possible for some antibiotic-sensitive mutants. Selection for temperature-sensitive mutants, however, resulted in less than a 2-fold increase in the frequency of such mutants, probably because of the heterogeneity ofthis mutant category. It is likely that only that fraction of temperature-sensitivemutations which rapidly and reversibly blocks macromolecular synthesis is selected by this technique.

Anti-Bacterial Agents↗
PubMed1968

Asparagine synthetase activity of mouse leukemias.

Various transplanted leukemias and normal tissues of the mouse were tested for asparagine synthetase activity. Leukemias susceptible to suppression by asparaginase have little or no synthetase activity. In contrast, leukemias insensitive to asparaginase exhibit substantial and often very high asparagine synthetase activity. Asparaginase-resistant variants of sensitive leukemias also have considerable synthetase activity. Thus the requirement by certain malignant cells of exogenous asparagine, which entails sensitivity to asparaginase, may be ascribed to lack of asparagine synthetase. Development of asparaginase-resistant variants from asparaginase-sensitive lines is consistently associated with acquisition of asparagine synthetase activity.

Animals↗
PubMedDate not supplied

Preparation of antihemophilic factor and fibronectin from human plasma cryoprecipitate.

Starting with human plasma cryoprecipitate, fibronectin was separated from antihemophilic factor (AHF) by fractional precipitation under mild conditions resulting in excellent recovery of AHF in the supernatant solution of the cryoprecipitate. Separation of fibronectin enabled accelerated sterile filtration of the supernatant solution containing AHF even after three- to fourfold concentration (by ultrafiltration) to desired potency. The sterile AHF concentrate, dispensed at 1000 u per vial and lyophilized, was completely dissolved within 3 minutes upon addition of 30 ml of pure water. The expected increment in circulating factor VIII and its hemostatic effects were found following intravenous infusion into factor VIII-deficient patients. Yield of AHF of five successive batches, each starting with the cryoprecipitate from some 12,000 units of fresh-frozen plasma, averaged 51 percent. The fibronectin precipitate was purified by affinity on insolubilized gelatin with chaotropic elution at pH 5.5 followed by removal of the chaotrope by diafiltration. Thermal denaturation of adventitious fibrinogen resulted in electrophoretically pure fibronectin which, following lyophilization and reconstitution with pure water, retained biological properties in an in vitro assay designed to reflect opsonic activity. The yield of fibronectin for seven successive batches, each starting with the cryoprecipitate from some 900 units of fresh-frozen plasma, averaged 10 percent.

Blood Transfusion↗
PubMedDate not supplied

Inactivation of viruses in labile blood derivatives. I. Disruption of lipid-enveloped viruses by tri(n-butyl)phosphate detergent combinations.

Use of the organic solvent, tri(n-butyl)phosphate (TNBP), and detergents for the inactivation of viruses in labile blood derivatives was evaluated by addition of marker viruses (VSV, Sindbis, Sendai, EMC) to anti-hemophilic factor (AHF) concentrates. The rate of virus inactivation obtained with TNBP plus Tween 80 was superior to that observed with ethyl ether plus Tween 80, a condition previously shown to inactivate greater than or equal to 10(6.9) CID50 of hepatitis B and greater than or equal to 10(4) CID50 of Hutchinson strain non-A, non-B hepatitis. The AHF recovery after TNBP/Tween treatment was greater than or equal to 90 percent. Following the reaction, TNBP could be removed from the protein by gel exclusion chromatography on Sephadex G25; however, because of its large micelle size, Tween 80 could not be removed from protein by this method. Attempts to remove Tween 80 by differential precipitation of protein were only partially successful. An alternate detergent, sodium cholate, when combined with TNBP, resulted in almost as efficient virus inactivation and an 80 percent recovery of AHF. Because sodium cholate forms small micelles, it could be removed by Sephadex G25 chromatography. Electrophoretic examination of TNBP/cholate-treated AHF concentrates revealed few, if any, changes in protein mobility, except for plasma lipoprotein(s).

Blood Proteins↗
PubMedDate not supplied

Inactivation of viruses in labile blood derivatives. II. Physical methods.

The thermal inactivation of viruses in labile blood derivatives was evaluated by addition of marker viruses (VSV, Sindbis, Sendai, EMC) to anti-hemophilic factor (AHF) concentrates. The rate of virus inactivation at 60 degrees C was decreased by at least 100- to 700-fold by inclusion of 2.75 M glycine and 50 percent sucrose, or 3.0 M potassium citrate, additives which contribute to retention of protein biologic activity. Nonetheless, at least 10(4) infectious units of each virus was inactivated within 10 hours. Increasing the temperature from 60 to 70 or 80 degrees C caused a 90 percent or greater loss in AHF activity. An even greater decline in the rate of virus inactivation was observed on heating AHF in the lyophilized state, although no loss in AHF activity was observed after 72 hours of heating at 60 degrees C. Several of the proteins present in lyophilized AHF concentrates displayed an altered electrophoretic mobility as a result of exposure to 60 degrees C for 24 hours. Exposure to lyophilized AHF to irradiation from a cobalt 60 source resulted in an acceptable yield of AHF at 1.0, but not at 2.0, megarads. At 1 megarad, greater than or equal to 6.0 logs of VSV and 3.3 logs of Sindbis virus were inactivated.

Citrates↗
PubMedDate not supplied

Virus sterilization in platelet concentrates with psoralen and ultraviolet A light in the presence of quenchers.

The virucidal and functional effect of the treatment of platelet concentrates (PCs) with long-wave ultraviolet light (UVA) and the psoralen derivative 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT) was studied. Cell-free vesicular stomatitis virus (VSV) was completely inactivated (greater than or equal to 6.5 log10) on treatment of PCs with 25 micrograms per mL (85 microM) of AMT and with 20.7 J per cm2 (30 min) of UVA in the presence of air, or with 82.8 J per cm2 (2 hours) of UVA under conditions of reduced oxygen tension. When treatment was in air, the extent and rate of platelet aggregation in response to collagen measured after overnight storage were reduced to about 70 and 50 percent of control values, respectively; however, aggregation responses were similar to those of controls when PCs were treated under reduced oxygen tension. As a means of eliminating the necessity of oxygen depletion during AMT and UVA treatment, we examined the effects of the addition of quenchers of reactive oxygen species. The presence of 2 mM (2 mmol/L) mannitol during treatment of PCs with 25 micrograms per mL of AMT and 20.7 J per cm2 of UVA in air significantly improved the aggregation response and other in vitro indicators of platelet function and had little or no effect on VSV inactivation. Less benefit was observed with the other quenchers examined. Thus, the nucleic acid specificity of psoralen photoinactivation under reduced oxygen conditions may also be attainable when selected free radical scavengers such as mannitol are present during treatment in air.

Blood Platelets↗
PubMedDate not supplied

Functional role of amino terminus in ClC-3 chloride channel regulation by phosphorylation and cell volume.

AIM: This study investigated the functional role of the ClC-3 amino-terminus in channel regulation in response to changes in cell volume. METHODS: Wild-type sClC-3 tagged with a green fluorescence protein (GFP) at the C-terminus was used as a template to construct a number of deletion mutants which were functionally expressed in NIH-3T3 cells. Whole cell and single channel patch-clamp electrophysiology was used to determine the functional properties of heterologously expressed channels. RESULTS: The first 100 amino acids of the ClC-3 N-terminus were removed and the truncated channel (sClC-3DeltaNT) was functionally expressed. Immunocytochemistry confirmed membrane expression of both wtsClC-3 and sClC-3DeltaNT channels in NIH/3T3 cells. sClC-3DeltaNT yielded constitutively active functional channels, which showed no response to protein kinase C or changes in cell volume. Deletion of a cluster of negatively charged amino acids 16-21 (sClC-3Delta16-21) within the N-terminus also yielded a constitutively active open channel phenotype, indicating these amino acids are involved in the N-type regulation. Intracellular delivery of a thiol-phosphorylated peptide corresponding to N-terminal residues 12-61 (NT peptide) markedly inhibited sClC-3DeltaNT whole-cell and single-channel currents, further confirming the essential role of the N-terminus in volume regulation of channel activity. CONCLUSIONS: These data strongly suggest the N-terminus of sClC-3 channels acts as a blocking particle inhibiting the flow of anions through the channel pore. This 'N-type' regulation of sClC-3 channels may be an important transducing mechanism linking changes in cell volume and channel protein phosphorylation to channel gating.

3T3 Cells↗