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Biomedical subjects

D B Wilson

Publications and source records attributed to D B Wilson.

At least 307 records · Page 17Linked to original sources
PubMed1980

Premilking stimulation effects on milking performance and oxytocin and prolactin release in cows.

For effects on milking performance, 12 Holstein cows were subjected to four stimulation routines: a) no stimulation, b) manual stimulation, c) manual stimulation with delayed milking, and d) intravenous infusion of .75 IU of oxytocin. In an added experiment, effects of the first two treatments on milking performance and release of oxytocin and prolactin were measured. Milk yield, fat, and protein content were not affected by any treatment. Machine-on times were shorter and peak and average milk flow rates higher for manually stimulated and oxytocin and prolactin in sera at resting were 5.25 microU/ml and 16.5 ng/ml. Differences between mean peak concentrations of oxytocin (16.6 and 16.0 microU/ml) and prolactin (28.1 and 27.5 ng/ml) for stimulated and unstimulated cows were small. Mean oxytocin concentration in stimulated cows peaked at 2 min compared with 5 min for unstimulated cows. No difference in time of prolactin release was detected. The timing of oxytocin release, rather than maximal concentration, could be the most important factor affecting milking.

Animals↗
PubMed1980

Role of exogenous oxytocin in eliciting milk ejection in dairy cows.

The efficacy of small doses of exogenous oxytocin in eliciting milk ejection was measured in eight lactating Holstein cows. Treatments comprised intravenous administration of .02, .05, .10, and .30 IU of oxytocin. The smallest dose of oxytocin that induced milk ejection in all cows was .10 IU. Administration of .10 and .30 IU produced greater peak rates of milk flow and shorter milking times. Ranges for these two variables were 2.9 to 3.9 kg/min and 4.8 to 5.6 min. Variations in mild yield (8.2 to 9.1 kg/milking) were not significant, but more fat was harvested after administration of the two higher doses. Differences in peak concentrations of serum oxytocin were 17.7 to 21.2 microunits/ml. Differences in latent time before peak concentration was reached were 1.3 to 4.0 min.

Animals↗
PubMed1980

T cell lines with dual specificity for strong Mls and H-2 determinants.

To examine the relationship of T cell specificity for Mls vs H-2 determinants, BALB/c (H-2d,Mlsb)(d,b) T cells were stimulated repeatedly in vitro with H-2-compatible, Mls-incompatible DBA/2(d,a) stimulators. This line of T cells gave strong mixed-lymphocyte reactions to the priming Mlsa determinants but, in addition, gave appreciable responses to various foreign H-2 determinants. When this T cell line was subsequently stimulated over a period of 2 mo with Mlsa-negative cells of a particular foreign H-2 haplotype, e.g., H-2k, the cells gave high responses to H-2k determinants but only very low responses to third-party H-2 determinants. Significantly, the cells retained high reactivity for Mlsa determinants. In other experiments, BALB/c T cells positively selected to Mlsa,d-negative H-2-incompatible stimulator cells retained high reactivity for Mlsa determinants. The implications of these findings are discussed.

Animals↗
PubMed1980

Histochemistry of the developing notochord, perichordal sheath and vertebrae in Danforth's short-tail (sd) and normal C57BL/6 mice.

The development of the notochord, perichordal sheath and vertebrae was studied in C57BL/6 and Danforth's short-tail (Sd) mutant mice on days 9-14 of gestation, using histochemical stains to detect possible extracellular matrix (ECM) components or precursors. Stains used were periodic-acid Schiff (PAS) after diastase treatment (glycoproteins, neutral polysaccharides) and alcian blue (glycosaminoglycans). Embryos from C57BL/6Sfd mice were analyzed to establish a normal baseline. In 9-day normal (C57BL/6Sfd; +/+) embryos the notochord is an uninterrupted structure and contains PAS-positive, diastase-resistant granules, whereas in abnormals (Sd/+; Sd/Sd) the notochord is discontinuous and exhibits few, if any, granules. A notochordal sheath is present in normal and abnormal embryos on day 10 and stains with PAS, alcian blue and aniline blue; subsequently, it increases in thickness in normal, but not defective, embryos. In normal embryos, the notochord shows dilatations, and notochordal cells become vacuolated from 13 to 14 days. In contrast, the notochordal fragments of abnormals never develop dilatations, nor do the cells vacuolate. Organization of mesenchymal cells into specific patterns is observed initially in 11-day normal embryos; further mesenchymal organization into vertebral and intervertebral disc analgen occurs during days 13-14. In abnormal embryos, disturbance of mesenchymal cell organization is evident as early as day 11, and by day 12 aberrant patterns of organization have emerged. Mesenchymal cells of abnormal embryos also lack the typical distribution of PAS-positive, diastase-resistant granules that occurs in normal speciments. The possible relationship of these granules in notochordal and mesenchymal cells to ECM materials is discussed.

Animals↗
PubMed1980

Fine structure of the lumbosacral neural folds in the mouse embryo.

The neural folds in the lumbosacral region of the normal 8-day and 9-day mouse embryo were studied by means of transmission electron microscopy with and without lanthanum treatment. The cells showed an abundance of ribosomes, microtubules arranged parallel to the long axes of the cells, and microfilaments extending across the apices. At the luminal border junctional complexes were common, and an occasional midbody was seen stretching between adjacent cells nearing the end of telophase. In the 8-day embryos, gap junctional vesicles (annular nexuses) bounded by layered membranes and containing cytoplasm with ribosome-like material were commonly observed; at 9 days the vesicles were relatively rare. The lanthanum-treated material demonstrated that the tracer was able to pass through the subluminal junctional complexes and throughout the intercellular spaces. However, the space between the membranes of the gap junctional vesicles lacked lanthanum and thus apparently did not communicate with the intercellular space.

Animals↗
PubMed1979

The fine structure of cerebral capillaries in "overgrown" neural tissue.

Cerebral capillaries in "overgrown" neural tissue of chick embryo brains ranging in age from 5-18 days of incubation were studied by means of electron microscopy. The vessels in the abnormal tissue showed more extensive and prolonged interdigitations and overlapping of adjacent endothelial cells than did those in normal control brains. In the abnormal neural tissue the appearance and distribution of endothelial cell organelles was similar to that in normal tissue; however, the Golgi complex was less highly developed, and there was an increased amount of coated vesicles in the capillaries of the abnormal brains.

Animals↗
PubMed1979

E. coli galactose-1-phosphate uridyl transferase: N-terminal and C-terminal sequences.

A modified procedure for the purification of E. coli galactose-1-phosphate uridyl transferase (E.C. 2.7.6.12) was developed which reproducibly gives pure enzyme. The purified enzyme was shown to be a dimeric protein with a subunit molecular weight of 41,000 and its amino acid composition and content of free sulfhydryl groups were determined. The N-terminal and C-terminal amino acid sequences were found to be NH2-thr-gln-phe-asn-pro-val-asp and -ser(val leu)-ala-COOH respectively. This N-terminal sequence allowed the identification of the start of the transferase gene in the DNA sequence determined by GRINDLEY. Furthermore it appears to define a nine base intercistronic region between the epimerase and transferase genes.

Amino Acid Sequence↗
PubMed1979

Immunological studies of T-cell receptors. II. Limited polymorphism of idiotypic determinants on T-cell receptors specific for major histocompatibility complex alloantigens.

These studies explore the extent of genetic polymorphism in the expression of anti-MHC receptors by T cells in different strains of rats. This question was approached with the use of the model of specifically induced GVH resistance in F1 rats which has been shown to reflect a specific T-cell mediated immune response against parental strain T cell anti-MHC receptors specific for host alloantigens. When A/B F1 rats derived from MHC incompatibile matings are immunized with lymphocytes from one parental strain (A they display a specific resistance to anti-B GVH reactivity caused by T cells from that parental strain, but not anti-AGVH reactions from the other. In addition, they resist anti-B GHV reactivity by T cells from third-party donors (C, D, E,...), a finding taken to indicate that the idiotypes of anti-MHC receptors on T cells, recognized by other T cells, show little or no polymorphism. This conclusion suggests that anti-MHC receptors are shared in the species and may be encoded, at least partially, by germ-line genes.

Animals↗
PubMed1979

Gap junctional vesicles in the neural tube of the splotch (Sp) mutant mouse.

The lumbosacral region of the neural tube was studied by means of transmission electron microscopy in retrospectively confirmed normal (+/+; Sp/+) and abnormal (Sp/Sp) embryos of the splotch mutant mouse early on the ninth day of gestation when the caudal neural groove is normally in the process of closing to form the neural tube. In abnormal embryos, a consistent feature is the presence of gap junctional vesicles, particularly in the region of the neural groove which subsequently fails to close, whereas these structures are rarely observed in similar areas of normal embryos. The possible significance of gap junctional vesicles is discussed in terms of cellular adhesion during early neurogenesis.

Animals↗
PubMed1979

Cloning and expression of the yeast galactokinase gene in an Escherichia coli plasmid.

This report describes the construction and isolation of a plasmid, derived from pBR322, which carries a BglII restriction fragment of DNA containing the galactokinase gene from Saccharomyces cerevisiae. This was accomplished by the following procedure: (1) Purified galactokinase mRNA, labelled with 125I, was hybridized to BglII digests of yeast DNA employing Southern's filter transfer technique to identify a restriction fragment containing the galactokinase gene. (2) This fragment was partially purified by agarose gel electrophoresis, ligated into the BamHI site of pBR322 and transformed into Escherichia coli to generate a clone bank containing the galactokinase gene. (3) This bank was screened by in situ colony hybridization with galactokinase mRNA resulting in the identification of a plasmid carrying this gene. This plasmid DNA hybridized with the galactokinase mRNA to the same extent in the presence of absence of a large excess of unlabelled mRNA from cells that were not induced for galactokinase synthesis, while the same amount of unlabelled galactose-induced mRNA reduced the hybridization by 95%. When this plasmid was introduced into an E. coli strain deleted for the galactose operon it caused the synthesis of low levels of yeast galactokinase activity.

DNA, Recombinant↗
PubMed1979

Evaluation of the anti-emetic action of domperidone.

The findings of a study into the anti-emetic properties of domperidone are reported. When the drug was given prophylactically with either morphine or pethidine the study revealed that any anti-emetic property of domperidone was of short duration and that it would not be suitable as a prophylaxis against opiate-induced emesis. Domperidone is not being introduced into clinical practice in the United Kingdom on the basis of current study.

Adolescent↗
PubMed1978

Sequence of neuron origin in experimentally distorted brains of chick embryos.

The effects of proliferative disorders on the time and sequence of neuron origin in the optic tectum were studied in chick embryos in which "overgrowth" had been experimentally induced, Sixteen normal and fourteen abnormal embryos ranging in age from four through ten days of incubation were each given a single dose of thymidine[3H]. Comparisons were then made between 16-day normal and abnormal chick embryos with respect to the distribution tectum midway between its rostral and caudal boundaries. In the normal and abnormal tecta layers I-IV were generated on days 3-6. Differences occurred in the generation of the remaining layers. In the normal embryos layers V-VII arose on days 5-8 and layers VIII-XV on days 4-7; in the abnormal embryos layers V-VII originated on days 6-8 and layers VIII-XV on days 5-8. In addition to the delay in onset of neuron origin, the abnormal tectum also showed distorted lamination, particularly in layers VIII-XV which constitute the superficial regions of the stratum griseum and fibrosum superficiale. Despite the defect in time and sequence of neuron origin, the rostroventrolateral to caudodorsomedial gradient of maturity characteristic of the normal tecta was not disturbed in the abnormal tecta.

Age Factors↗
PubMed1978

Immunological studies of T-cell receptors. I. Specifically induced resistance to graft-versus-host disease in rats mediated by host T-cell immunity to alloreactive parental T cells.

The present studies extend our previous efforts to understand the immunological basis of specifically induced graft-versus-host (GVH) resistance in F1 hybrid rats. Immunization of F1 rats with alloreactive T-cell populations of parental strain origin induces a host-mediated T-cell response which is specific for anti-major hostocompatibility complex receptors on parental T cells. This protective immunity is rapid in onset and once induced, it provides a highly effective, specific resistance to lethal GVH disease which is radioresistant and can be adoptively transferred to syngeneic recipients.

Animals↗
PubMed1978

The fine structure of ventricular cells in the brains of mouse embryos homozygous for the loop-tail gene.

The neural tube in normal (+/+), heterozygous (Lp/+), and abnormal (Lp/Lp) mutant mouse embryos ranging in age from 10 to 12 days of gestation was studied by means of transmission electron microscopy. In the abnormal embryos, ventricular cells in defective regions of the brain show distortions and crowding together of internal cellular processes and a decrease in blebs and bulbous projections, as compared with their normal counterparts. At 12 days' gestation the abnormal brains show a scarcity of the T-shaped internal cellular processes characteristic of normal brains. The abnormal brains also show increased amounts of intercellular space and extensive gaps between the cells, particularly in basal regions. There are no striking differences between the normal and abnormal brains at 10 to 12 days' gestation with respect to the appearance and distribution of cilia, microfilaments, microtubules, tight junctions, and ribosomes.

Animals↗