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Biomedical subjects

D R Nelson

Publications and source records attributed to D R Nelson.

At least 235 records · Page 13Linked to original sources
PubMed1980

Peripheral serum progesterone and luteinizing hormone concentrations of goats during synchronization of estrus and ovulation with prostaglandin F2 alpha.

Prostaglandin F2 alpha (PGF2 alpha) (2 doses, 11 days apart) was given to 20 mixed-breed dairy does to synchronize estrus and ovulation. The dose of PGF2 alpha used was the free-acid equivalent of 8 mg which was divided between 2 injections at 0800 and 1200 hours. At the initiation of treatments, does were from day 0 (estrus) to day 18 of the estrous cycle. Seventeen of the doses exhibited estrus within a mean (+/- SE) interval of 53 +/- 2 hours after the first 0800-hour injection. Peripheral progesterone concentrations determined at daily intervals indicated that PGF2 alpha was luteolytic as early as day 4 of the cycle. Does were in the 8th to 12th days of the cycle at the time of the 2nd treatments with PGF2 alpha. Estrus was observed in all 20 does at 50 +/- 1 hour after the 0800-hour injections. Serum progesterone concentrations confirmed that luteolysis occurred in all of the does. In 19 does, concentrations of luteinizing hormone characteristic of a preovulatory peak were observed 55 +/- 2 hours after the 2nd 0800-hour injection. One doe did not demonstrate a luteinizing hormone peak within the 72-hour period. Laparotomies were performed 6 days after estrus, and ovaries were examined for corpora lutea. The mean number of corpora lutea was 2.0 +/- 1.0.

Animals↗
PubMed1979

Spinal analgesia and sedation of goats with lignocaine and xylazine.

Spinal anaesthesia of 20 does undergoing laparotomies was accomplished with epidural injections of 2 per cent lignocaine at a dosage of 1 ml per 4.55 kg in 16 goats. Epidural injection resulted in paralysis lasting 198.5 minutes +/- 36.6 minutes. Subarachnlid injection resulted in paralysis lasting 180.8 minutes +/- 44.9 minutes. Xylazine was given intramuscularly at the dosage of 0.11 mg per kg after posterior paralysis was complete. These treatments resulted in effective analgesia for surgical intervention. Recovery was complete and uneventful in all goats. An additional 26 operations were performed using this treatment and results were equally satisfactory.

Analgesia↗
PubMed1978

Effects of xylazine hydrochloride on urine in cattle.

Urine volume, urine pH, and urine glucose concentration were monitored for up to 24 hours after physiological saline or one of two dosage levels (0.22 mg/kg or 0.44 mg/kg) of xylazine was administered to cows. During the first 2 hours after xylazine was given, urine output was greatly increased (relative to the control animals), with the high dosage group having more output than the low dosage group. The influence of the drug on urine volume had ended by 5 hours after injection when urine output in both dosage groups had returned to that of the control group. Glucose was detected in the urine of xylazine treated animals, beginning at 15 to 30 minutes after injection, reached a maximum at 2 hours, and was undetectable at 5 to 6 hours. Urine pH decreased in control and treated animals, but in treated animals the pH began to increase 2 hr after treatment.

Animals↗
PubMed1977

Kinetic analysis of the binding of immunoglobulins IgG1 and IgG2 to bovine mammary cells.

Previous reports were confirmed that specific binding sites exist on bovine mammary cells near parturition presumably involved in the transfer of immunoglobulins IgG1 and IgG2 across the mammary gland at the time of colostrum formation. Determination of the kinetic parameters of these binding sites using 125I-labeled IgG1 and IgG2 immunoglobulins indicated the presence of sites with association constants (Ka) of about 5 - 10(8)--10 - 10(8)M-1 for both subclasses during normal lactation with about 9000 and 3000 sites per cell for each, respectively. The number of IgG1 sites tended to increase as the time of parturition approached. In addition, a new group of sites numbering about 5000 per cell with very strong binding for IgG1 (Ka about 45 - 10(8)M-1) appeared on the cells about a week before parturition. The numbers and affinity of the IgG1 and IgG2 binding sites bear a relationship to the approximate 7 : 1 ratio of these immunglobulin subclasses found in colostrum and normal milk and to the time of maximum colostrum formation. The results support the premise that a highly selective transport mechanism exists in the bovine mammary epithelial cell for the transfer of IgG1 and IgG2 immunoglobulins from blood to the lacteal secretions.

Animals↗
PubMed1977

Association of hydrogen metabolism with methanogenesis in Lake Mendota sediments.

Lake Mendota sediments were studied to determine the role of H2 in sediment methanogenesis. H2 was generally not detectable in sediment. The addition of H2 to sediment significantly increased methanogenensis. The amount of methane produced was proportional to the concentration of hydrogen added. H2 addition stimulated the reduction of CO2 to methane, but did not significantly stimulate the conversion of methanol or the methyl position of acetate to methane. Various organic compounds also stimulated sediment methanogenesis. Formate, ethanol, and glucose were shown to serve as electron donors for CO2 reduction to methane. The addition of formate to sediment resulted in H2 evolution. H2 was not deith the phenomenon of interspecies hydrogen transfer. The results indicate that hydrogen is an important intermediate and a rate-limiting factor in sediment methanogenesis.

Acetates↗
PubMed1976

The effect of oxygen on the enzymes concerned in the metabolism of 5-hydroxytryptamine by rat brain and liver preparations.

1. The effect of oxygen concentration at 1 atm on rat enzyme systems concerned in the synthesis and degradation of 5-hydroxytryptamine was studied in vitro. 2. Oxygen activated tryptophan hydroxylase and the deamination of both 5-hydroxytryptamine and tyramine by monoamine oxidase. 3. Oxygen did not affect the activities of 5-hydroxytryptophan decarboxylase or peroxidase.

Air↗
PubMed1976

Cellular studies of mammary tissue from cows hormonally induced into lactation: lactose and fatty acid synthesis.

Temporal changes in ability of mammary gland to synthesize lactose and fatty acids were identified during the treatment of cows hormonally induced to lactate, and animal differences were compared to subsequent milk production. Hormonal treatment involved 17 beta-estradiol + progesterone on days 1 to 7 and dexamethasone on days 17 to 19. Mammary tissue obtained by biopsy on days 0, 8, 16, and 26 of treatment was examined for biosynthetic capacity by tissue slice incubations. In terms of peak daily milk yield, one cow was very successful (greater than 30 kg), two were intermediate (9 to 10 kg), and one cow was unsuccessful (less than 3 kg). Differences between cows in the capability to synthesize lactose and fatty acids were evident as early as day 8 and were further magnified by day 16. In particular, the tissue from the successful cow was undergoing lactogenesis by day 8 while this was not evident until the day 16 biopsy sample in the less successful cows. In contrast to the other cows, tissues from the unsuccessful animal regressed in its ability to synthesize lactose and fatty acids between day 16 and 26. Relative differences between animals in measurements of metabolic capacity were consistent with subsequent milk production.

Acetates↗
PubMed1975

Citrate cleavage enzymes from developing soybean cotyledons: incorporation of citrate carbon into Fatty acids.

Data are presented which demonstrate a citrate cleavage enzyme in the supernatant of a developing soybean (Glycine max L. Merr., var. Harosoy 63) cotyledon homogenate following a 126,000g spin for 2 hours. Activity of the enzyme was observed directly in the supernatant enzyme preparation and in a desalted supernatant preparation by measuring the formation of acetylhydroxamate. Acetylhydroxamate production was dependent on citrate and coenzyme A. The reaction increased with time, citrate, and coenzyme A concentrations.Involvement of the enzyme in lipid synthesis was investigated by the incorporation of carbon from citrate-1,5-(14)C into fatty acids. Incorporation shows a pH optimum at 8.5, a temperature optimum at 30 C, and a dependence on ATP and coenzyme A. The reaction is linear throughout the range of extract concentrations tested and is linear as a function of time for 1 hour. Isotope was distributed primarily in unsaturated fatty acids.

Journal Article↗
PubMed1975

Normal and branched alkanes from cast skins of the grasshopper Schistocerca vaga (Scudder).

Gas-liquid chromatographic and mass spectral analyses of the hydrocarbons from cast skins of the grasshopper Schistocerca vaga (Scudder) demonstrated the presence of four homologous series of alkanes: n-alkanes (35%), monomethylalkanes (24%), dimethylalkanes (35%), and trimethylalkanes (3%). The methyl branches were located towards the center of the molecule, and no 2- or 3-methylalkanes were detected by mass spectrometry. The branched alkanes occurred as isomeric mixtures with the methyl group(s) usually located on carbon atom 11, 13, 15, or 17. In the di- and trimethylalkanes, the branch points had isoprenoid spacing. Of the total hydrocarbons, the major component of the n-alkane series was nonacosane, 23%; of the monomethylalkanes, it was 11-, 13-, 15-, and 17-methylpentatriacontanes, 13%; of the dimethylalkanes, 9,13-, 11,15-, 13,17-, and 15,19-dimethylpentatriacontanes, 20%; and of the trimethylalkanes, 11,15,19- and 13,17,21-trimethylpentatriacontanes, 1%.

Alkanes↗