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Biomedical subjects

C A White

Publications and source records attributed to C A White.

At least 91 records · Page 5Linked to original sources
PubMed1989

Response properties in the dorsal lateral geniculate nucleus of the adult cat after interruption of prenatal binocular interactions.

1. Single-cell recordings were made in the magnocellular layer of the dorsal lateral genicule nucleus (dLGN) of five adult cats in which prenatal binocular interactions were interrupted by monocular enucleation at known gestational ages. Three cats (early enucleates) had one eye removed on either embryonic day 44.48, or 49, before retinogeniculate inputs are segregated into uniocular layers. Two other (late enucleates) underwent this procedure on embryonic days 55 and 58, when segregation is well advanced. Responses were compared with those obtained from recordings in the A and A1 layers of the dLGN of seven normal adult cats. 2. Cells were classified as ON or OFF by the use of spots of light and as X or Y based on a test of linearity of spatial summation with the use of counterphased sinusoidal gratings. Receptive-field size and spatial resolution were also obtained. 3. The dLGN of prenatally enucleated cats contains a dorsal magnocellular layer and a ventral parvocellular layer. In early enucleates, only an occasional hint of a cell-sparse interlaminar zone was apparent, located between the magnocellular and parvocellular layers. In late enucleates, a prominent cell-sparse band was observed contralateral to the remaining eye, in a region that would most likely correspond to layer A1 in the normal dLGN. No such cell-sparse band was seen ipsilateral to the remaining eye in late enucleates. 4. Eighty-six X cells and 22 Y cells were studied in the enucleates. Both cell types were found at all depths of the magnocellular layer. All but a few neurons had concentric ON-center or OFF-center receptive fields that were normal in size. The topography of receptive fields also appeared normal. In addition, spatial resolution of X and Y cells was similar in experimental and control animals. 5. In early enucleates there was a higher percentage of X cells and a lower percentage of Y cells than normal. The change in X-to-Y ratio was shown to be because of both a gain in cells with X properties and a loss of cells with Y properties. The distribution of dLGN somal sizes in the early enucleates was comparable with controls, so the change in X-to-Y ratio most likely did not result from an electrode sampling bias. It was suggested that the X-to-Y ratio difference could stem from the abnormalities in retinogeniculate terminal arbors that have been shown to follow early eye removal.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

A Ca2(+)-sensitive glycoprotein, GP90, associated with the cytoskeleton from brain and gizzard.

We describe here the expression during development, tissue distribution and molecular properties of GP90: a major concanavalin A (ConA)-binding glycoprotein present in the neuronal membrane skeleton from chicken brain. GP90 is co-isolated with, and has a similar developmental profile to contactin (previously called GP130). In whole brain, GP90 undergoes rapid synthesis between embryonic days 10 and 12. Unlike contactin, it is not restricted to nervous tissue and is quite abundant in gizzard, where there are two antigenically related proteins of 100K and 90K (K = 10(3) Mr). In both brain and gizzard GP90 and (GP100) are enriched in the membrane skeleton fraction. Trypsinization of live cells suggest that GP90 from gizzard is related to GP100 by the removal of a polypeptide chain. GP90 from both neurones and gizzard cells is protected from proteolysis by the presence of extracellular Ca2+. In the absence of Ca2+ a soluble fragment of approximately 70K can be released from the surface of cells indicating that a large fraction of GP90 is extracellular. Deglycosylation of GP90 from brain using endoglycosidase F demonstrates the presence of at least five carbohydrate chains and a polypeptide chain of approximately 80K. Immunofluorescence studies show that GP90 is exposed on the surface of cultured neurones, gizzard cells and most glial cells with the exception of Schwann cells. It is observed in clusters or patches even when cells are prefixed, suggesting this may be the normal distribution of GP90.

Animals↗
PubMed1988

The isolation, purification and some properties of pheromaxein, the pheromonal steroid-binding protein, in porcine submaxillary glands and saliva.

Pheromaxein, the 16-androstene steroid-binding protein with a relative molecular mass of 15,000 was isolated in sub-milligram quantities from the submaxillary gland and saliva of the Gottingen miniature boar, after a fourfold purification involving the following methods: ultrafiltration for submaxillary gland cytosols and ethanol precipitation for saliva, Concanavalin-A-Sepharose affinity chromatography, sodium dodecyl sulphate polyacrylamide gel electrophoresis, 'Extractigel-D' affinity chromatography (to remove sodium dodecyl sulphate) and fast protein-liquid chromatography. Yields of purified pheromaxein obtained after fast protein-liquid chromatography represented 10-20% of total protein present in an ultrafiltrate of a submaxillary gland cytosol. Fast protein-liquid chromatography separated the alpha- and beta-charge isomers of pheromaxein which were shown to have isoelectric points of 4.78 and 5.35 respectively on flat-bed isoelectric focusing. Some data are provided for the variable occurrence of the isomeric forms of pheromaxein in relation to different breeds of pig. Five 16-unsaturated steroids showed the highest binding to pheromaxein. Other steroids of the 5 alpha- and 5 beta-androstane series also showed some binding to pheromaxein, i.e. 17 beta-hydroxy-5 alpha-androstan-3-one (19.2%), with 5 alpha-androstan-3-one, which has a similar urinous odour to 5 alpha-androst-16-en-3-one, showing the greatest binding (42.6%) relative to 5 alpha-androst-16-en-3-one (100%).

Animals↗
PubMed1988

Surgical sterilization at the time of cesarean delivery.

The cesarean section operation has been recognized for more than a century as an ideal time for the obstetrician to effect sterilization, usually with minimal morbidity, by way of one of the methods of tubal ligation. The physician must choose between simple, quick methods such as the Pomeroy or Parkland, with their slightly higher but acceptable failure rates, or the more elaborate and foolproof methods that involve burial of the tubal ends, such as the Irving or Uchida, which are technically more difficult and time consuming. The authors stress that whichever procedure is utilized, the surgeon must resist the desire to elaborate on proven techniques; otherwise, higher than published failure rates may result. It is important for the patient to understand the risks, both of immediate morbidity and remote failure, and to give her informed consent. Attentive presterilization counseling may identify the patient who will regret the loss of her fertility.

Cesarean Section↗
PubMed1987

Correction for bacterial loss in in vitro dilution models.

A new method to correct for bacteria lost to dilution in in vitro kinetic models is presented which includes the influence of the stationary bacterial growth phase. The method imposes an upper limit on bacterial density, in contrast to previous methods.

Bacteria↗
PubMed1986

Use of the erythrocyte rosette test to screen for excessive fetomaternal hemorrhage in Rh-negative women.

The possibility of Rh immune globulin failure exists when a fetomaternal hemorrhage exceeds 25 to 30 ml of whole blood and only one 300 micrograms vial of Rh immune globulin is administered. In this prospective study of 1000 consecutive Rh-negative women who were delivered of Rh-positive newborn infants, the presence of fetal erythrocytes in maternal blood was identified with use of both the Du test read microscopically and the erythrocyte rosette test. All positive tests prompted fetomaternal hemorrhage quantification with use of a modified Kleihauer-Betke acid elution test. Nineteen patients demonstrated a positive rosette test, and the only positive Du tests were in five of these 19. Six of the nineteen had levels of greater than 30 ml of whole blood for an incidence of 0.6% for fetomaternal hemorrhage exceeding the protective capabilities of the standard Rh immune globulin dosage. In experiments with simulated fetomaternal hemorrhage, all 79 samples, containing from 2.5 to 70 ml of fetal whole blood, were positive according to the erythrocyte rosette test. Applying the Du test to the same samples resulted in a 30% false negative rate at the level of a 30 ml simulated hemorrhage. Based on sufficient sensitivity, ease of interpretation, and reasonable cost, the rosette test appears to be a superior screening test for excessive fetomaternal hemorrhage in Rh immune globulin candidates.

Blood Volume Determination↗
PubMed1985

Influence of ampicillin elimination half-life on in-vitro bactericidal effect.

Escherichia coli ATCC 12407 was exposed in an in-vitro kinetic model to multiple dose ampicillin regimens differing in simulated drug elimination half-life but with equal dosage intervals and similar dose levels. Bacterial sensitivity was monitored during drug exposure. Greater bactericidal effect was observed with long half-life regimens. The development of rapid low-level resistance was not influenced by the half-life. Results suggest that in-vivo drug activity may be improved by increasing the drug elimination half-life.

Ampicillin↗
PubMed1985

Two monoclonal antibodies selective for human mammary carcinoma.

Mouse myeloma cells were fused with spleen cells from BALB/c mice immunized with the MCF-7 human mammary carcinoma cell line. Among hybridomas, two (3B18 and 15A8) were selected and cloned. Hybridoma 3B18 produces kappa-IgG1 antibodies that react with a cytoplasmic component of MCF-7 cells. In immunoperoxidase assays, 3B18 reacts with 27 of 31 specimens of human mammary carcinoma. It reacts most consistently with poorly differentiated and infiltrating ductal breast cancers, but it also reacts with isolated cells in 3 of 5 benign mammary pathological lesions with a variable distribution. The antibody does not react with normal mammary epithelium. It does not react with any normal human tissues, and it reacts with only one of 19 other cancers tested. Hybridoma 15A8 produces kappa-IgG1 antibodies that react with the surface membranes of the cells of two human breast cancer cell lines but not with a human fibroblast cell line. In immunoperoxidase assays, the antibody reacted with 28 out of 31 human mammary carcinomas. The antibody also reacts more weakly with normal human epithelial cells of breast, renal proximal tubule, skin, esophagus, and salivary gland, but no other normal tissue. The antibody was unreactive with 14 of 18 other malignant tissues tested. Since 3B18 and 15A8 detect antigens found predominantly in human mammary carcinomas and, possibly, distinguish overlapping categories of human mammary carcinomas, they may prove useful in determining the cellular lineage from which human mammary carcinomas arise, or they may have other clinical applications in breast cancer.

Antibodies, Monoclonal↗
PubMed1983

Membranous nephropathy associated with an unusual phenotype of chronic lymphocytic leukemia.

The nephrotic syndrome is uncommon in patients with chronic lymphocytic leukemia. When present, the most frequently documented cause is membranous nephropathy, although several other glomerular lesions have also been described. This report describes a patient with chronic lymphocytic leukemia of an unusual surface marker phenotype recently suggested to be associated with an increased incidence of proteinuria. Renal biopsy specimens demonstrated membranous glomerulonephritis. Immunofluorescence staining demonstrated glomerular deposition of IgG and C3, but not the human T-lymphocyte antigen, T65, which had been found on circulating leukemia cells.

Complement C3↗
PubMed1983

Anti-D antibodies in D- and Du-positive women: a cause of hemolytic disease of the newborn.

Regardless of the decrease in Rh sensitization as a cause of hemolytic disease of the newborn, antenatal antibody screening must be performed in all patients to detect not only anti-D sensitization, but other less common antibodies capable of provoking hemolytic disease of the newborn. The relative incidence of hemolytic disease of the newborn due to sensitization to such irregular antibodies as Kell, Kidd, and Duffy is increasing. We report here five patients who had D- or Du-positive blood with antenatal anti-D sensitization, and whose neonates had hemolytic disease of the newborn of varying severity. Blood that is D- and Du-positive with anti-D has been classified by Tippett; such blood types lack part of the D mosaic and are considered to be "D variants" yet are typed routinely as Rh positive. Anti-D antibody produced by D- and Du-positive blood is indistinguishable from the ordinary variety of anti-D.

Black People↗
PubMed1983

An automated Elson-Morgan assay for 2-amino-2-deoxy-hexoses, with increased sensitivity.

The Elson-Morgan assay for 2-amino-2-deoxyhexoses, despite its many modifications, can still give variable results because of slight variations in reaction conditions. An automated method is reported which uses microgram samples and provides greater sensitivity than hitherto possible. The use of sodium orthophosphate and optimisation of the concentrations of the reagents provide conditions that are more stable, and results that are more reliable, than any previously reported.

Autoanalysis↗
PubMed1983

The microflora of stored coleslaw and factors affecting the growth of spoilage yeasts in coleslaw.

Saccharomyces dairensis and Sacch. exiguus were isolated as the spoilage flora of coleslaw stored at 5 degrees and 10 degrees C. The growth of these yeasts in mixtures of mayonnaise with vegetable was inhibited by onion. Mayonnaise alone killed the yeasts, primarily because of its content of acetic acid and this effect increased as the temperature was increased and as the pH was decreased. Addition of cabbage or carrot tissue removed the lethal effect of mayonnaise and allowed spoilage, by absorbing acetic acid and increasing the pH.

Bacteria↗
PubMed1982

Ulcerating enteritis associated with flucytosine therapy.

Flucytosine-associated diarrhea has been previously described in 6%-10% of patients receiving the drug. A potentially fatal ulcerating enterocolitis has been reported in 4 patients. In none of these reports has radiologic or pathologic data been presented. This report describes a case of flucytosine-associated ulcerating enteritis in which the small bowel x-ray demonstrated severe luminal narrowing, ulceration, and marked separation of loops of bowel. Ileal biopsy revealed an erosive enteritis with mucosal inflammatory infiltrate and disruption of the surface epithelium. Discontinuation of the drug resulted in total resolution of the clinical and radiologic abnormalities.

Aged↗