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Biomedical subjects

J L Robinson

Publications and source records attributed to J L Robinson.

At least 73 records · Page 4Linked to original sources
PubMed1989

Amblyomma variegatum ticks and the occurrence of bovine streptothricosis in Antigua.

The association between the occurrence of Amblyomma variegatum ticks and streptothricosis was studied on the Caribbean island of Antigua. The prevalence of streptothricosis was higher on animals having A. variegatum ticks compared to that of animals not infested with A. variegatum ticks. There was a steady increase in the prevalence of severe lesions as the level of infestation with adult A. variegatum ticks increased. However the distribution of skin lesions could not be related to the predilection feeding sites of adult A. variegatum ticks.

Abattoirs↗
PubMed1989

Embryonic mortality attributed to inherited deficiency of uridine monophosphate synthase.

The deficiency of uridine-5'-monophosphate synthase is inherited as an autosomal recessive trait in Holstein-Friesian cattle. Heterozygotes are characterized by half normal activity of uridine monophosphate synthase, as measured in erythrocytes. Matings between heterozygotes for the deficiency have produced 31 pregnancies lasting at least one month, but only 23 full-term calves, including 9 homozygous normal and 14 heterozygotes. That the eight embryos were not carried to term is consistent with the probability of a homozygous-deficient genotype and are lost around 40 d of gestation. Although the homozygous deficiency of uridine monophosphate synthase is lethal embryonically in cattle, homozygotes for the analogous human condition have been born alive.

Animals↗
PubMed1989

Effects of home-based, informal social support on child health.

To enhance mother-infant interaction, paraprofessional home visitors provided parents with emotional support, information, and help in using community resources during pregnancy and throughout the infants' first 14 months. This study reports effects on child health. Both home-visited women and controls made good use of well-child care. Home-visited women made greater use of sick-child care (p = 0.002), most of which was appropriate. The greater use of sick-child care was concentrated among mothers with moderate or high family stress, with whom home visitors had closer relationships. Case histories showed a variety of individual effects on parents.

Child Health Services↗
PubMed1989

Evaluation of histopathologic and physiologic changes in cows having premature births after consuming Ponderosa pine needles.

Premature calving, typified by early expulsion (17 to 43 days) of weak or dead calves and accompanied by retained placentas, was induced in 8 of 9 pregnant cows fed a mixture of Ponderosa pine needles and alfalfa hay. Five control cows of comparable gestation age fed only alfalfa hay maintained normal pregnancies until they were euthanatized at the time the pine needle-treated cows were producing premature calves. Serum specimens from all cows were assayed for progesterone concentration and ovaries and placentomes were examined for histopathologic changes. There were no bacterial, fungal, chlamydial, or viral agents determined to be associated with the premature births. Serum progesterone concentration in the treated cows decreased progressively and were 0.4 to 1.5 ng/ml at the time of premature calving. Histopathologic changes were evident in the placenta and corpora lutea of treated cows only. The number of binucleate trophoblastic giant cells in placentomes was less than normal and the number of necrotic luteal cells in corpora lutea was greater than normal.

Animals↗
PubMed1989

Clinical chemistry outside laboratories: report of a second survey.

The growth in the use of small portable analysers outside hospital laboratories has been a cause of concern to laboratory practitioners. This has been partly because of a perceived threat to laboratory careers and partly because of fears that the quality of testing would be poor, with a consequent danger of patients being placed at risk. The evidence in this paper indicates that the use of equipment outside laboratories is still increasing in many areas. Despite the fears which have been expressed, little attention is being given to operator training, service costs, safety and many other aspects; only rarely has responsibility for the quality of results been accepted.

Chemistry, Clinical↗
PubMed1988

MAC of I-653 in beagle dogs and New Zealand white rabbits.

The minimum alveolar concentration (MAC) of I-653 was determined in six beagle dogs and four New Zealand white rabbits. The MAC values (+/- SD) were 7.2 +/- 1.0 atm % for dogs and 8.9 +/- 0.3 atm % for rabbits. Comparison of these results with published MAC values for other anesthetics indicate that I-653 is one-third to one-eighth as potent as currently available volatile anesthetics (enflurane, isoflurane, and halothane). From these data and previous reports, human MAC was projected to be approximately 5.1 atm %.

Anesthesia, Inhalation↗
PubMed1987

Fasting and L-364,718 prevent cholecystokinin-induced elevations of plasma insulin levels.

Sulfated CCK-8 but not non-sulfated CCK-8 induced a dose-dependent increase in plasma insulin levels in fed mice. In fasted mice, however, the CCK peptides caused a non-significant to minimal elevation of plasma insulin. Refeeding fasted mice for 1 h prior to CCK-8-S administration was sufficient to cause a significant elevation of plasma insulin levels. The peripheral CCK antagonist, L-364,718, prevented the CCK-8-S-induced elevation of plasma insulin observed in fed mice. In conclusion, CCK produces a nutrition-dependent increase in plasma insulin levels in vivo via an action upon peripheral CCK receptors.

Animals↗
PubMed1987

Evaluation of disposable cartridges for trace enrichment from aqueous solutions.

Selected aromatic hydrocarbons, phthalate esters, and food, drug and cosmetic (FD&C) dyes are isolated from aqueous solutions with Chrom-Prep PRP-1 and Sep-Pak C18 cartridges. The Chrom-Prep cartridges demonstrate greater adsorption capacity for model aromatic hydrocarbons and phthalate esters than Sep-Pak C18 cartridges; however, the latter exhibits greater capacity for the FD&C dyes, which have breakthrough volumes that are a function of pH. Both cartridge types show a small amount of analyte leakage during the trace enrichment step, which is measured by monitoring the cartridge effluents for the presence of 14C-labeled solute. Two PRP-1 cartridges connected in tandem reduce the amount of activity in the effluent by approximately one half.

Benzo(a)pyrene↗
PubMed1987

Characterization of UMP synthase in dairy cattle heterozygous for a lethal recessive trait.

UMP synthase was characterized biochemically in dairy cattle heterozygous for a deficiency of this enzyme. Both activities comprising this bifunctional enzyme are decreased, with OMP decarboxylase more affected than orotate phosphoribosyltransferase. Immunotitration of UMP synthase activity revealed the presence of the protein product of the mutant allele in the heterozygous animals. UMP synthases from normal and deficient cattle were not distinguished from one another by kinetic constants, responses to inhibitors, pH profiles, or thermal lability. It was concluded that the 50% reduction in enzyme activity in heterozygous cattle is the result of the presence of only half the normal level of catalytically active UMP synthase.

Animals↗
PubMed1987

Deficiency of UMP synthase in dairy cattle: a model for hereditary orotic aciduria.

Deficiency of uridine-5'-monophosphate (UMP) synthase in dairy cattle, a condition analogous to human hereditary orotic aciduria, is reviewed with consideration of similarities and differences between the enzyme deficiency in humans and cattle. New findings regarding the bovine condition are reported including presence of the enzyme deficiency in numerous tissues and absence of substantial effects on other aspects of nucleotide metabolism. Specifically, erythrocyte concentration of phosphoribosylpyrophosphate (PRPP) and activities of PRPP synthetase, adenine phosphoribosyltransferase, and hypoxanthine-guanine phosphoribosyltransferase appear to be normal in cattle heterozygous for UMP synthase deficiency.

Adenine Phosphoribosyltransferase↗
PubMed1987

Deficiency of uridine monophosphate synthase in Holstein cattle: inheritance and body measurements.

Blood samples and body measurements were obtained from daughters of seven Holstein bulls previously shown to have a partial deficiency of uridine monophosphate (UMP) synthase and presumed to be heterozygous for the condition. Erythrocyte UMP synthase for 85 daughters showed a bimodal distribution with 42 having half the normal activity of 43 others. Furthermore, each bull had 50% of his daughters represented in each group, a finding fully consistent with the heterozygous designation of these bulls. Because UMP synthase is needed for pyrimidine biosynthesis and hence DNA and RNA metabolism, it was hypothesized that a partial deficiency could result in slower growth and smaller size for affected animals. Body measurements, as estimates of growth and size, included body length, wither height, hip height, hip width, rump length, pin width and taped body weight. Although measurements varied by age, differences between normal and heterozygous females were not found. One-half the normal activity of UMP synthase in cattle was adequate for near normal growth. Additionally, herd life was not significantly affected in heterozygous females.

Animals↗
PubMed1987

Incidence and inheritance of deficiency for uridine monophosphate synthase in Holstein bulls.

A partial deficiency of uridine monophosphate synthase has been discovered among Holstein dairy cattle wherein affected animals have half the normal activity of this enzyme and are heterozygous for a condition presumed to be lethal in the homozygous recessive state. A random sample of 287 dairy bulls, active in artificial insemination organizations, were assayed for their activity of uridine monophosphate synthase. Four bulls displayed reduced enzyme activity (heterozygotes) corresponding to a 1.4% incidence and were closely related to a common ancestor, Bull-X. Testing a total of 75 male descendants of Bull-X has uncovered 22 heterozygotes. Heterozygotes include 5 sons, 15 grandsons, 1 a double grandson, and 2 great grandsons of Bull-X. Reproductive failure from this enzyme deficiency has been minimal because matings between close relatives have been infrequent. If the incidence of heterozygotes active in artificial insemination increases, avoidance of matings between close relatives will become an inadequate safety measure to maintain reproductive fitness. Random mating of male heterozygotes to a female population with 2% incidence of heterozygotes may imply an additional .5% embryonic loss relative to matings involving bulls that are normal for uridine monophosphate synthase.

Animals↗
PubMed1986

Influence of age, sex, lactational state and exogenous growth hormone on erythrocyte UMP synthase in dairy cattle.

UMP synthase activity was determined in erythrocytes of Holstein cattle to assess differences attributable to age, sex, lactational state, and exogenous growth hormone. Newborns had 80% more UMP synthase activity per ml erythrocytes than mature cattle. Males had 10% more UMP synthase activity than females of the same age. Lactating and non-lactating mature females did not differ in UMP synthase activity. Over the first six weeks of life, the decrease in UMP synthase activity was less pronounced in calves partially deficient for the enzyme. Ten daily injections of growth hormone altered neither UMP synthase activity in erythrocytes nor orotic acid concentrations in milk and urine.

Aging↗
PubMed1986

Effect of vasopressin and phenylephrine on arterial pressure and heart rate in conscious dogs.

The effect of arginine vasopressin (AVP) and phenylephrine (PE) infusions on mean arterial pressure (MAP) and heart rate (HR) were compared in conscious dogs with all autonomic receptors intact (I), during muscarinic blockade (MB) and during ganglionic blockade (GB). After either MB or GB, the dose-MAP response curve for AVP and PE was shifted to the left of the I response curve; a greater shift was observed with AVP than with PE. The MAP threshold after GB for AVP and PE occurred at 10 and 50% of the threshold dose observed during the I response, respectively. Not only did the MAP threshold occur at a lower dose after MB and GB, but also the slope of the response curve was steeper than that of the I response. Comparing the amount of drug necessary to increase MAP 25 mmHg above control for PE and AVP before and after GB, the intact PE response required 4.3 +/- 1.0 (P less than 0.01) times more drug than during GB versus the intact AVP required 16.8 +/- 2.8 (P less than 0.01) times more drug than during GB. The baroreflex control of HR when all receptors were intact was 3.4 +/- 0.4 (P = 0.001) times more sensitive during AVP compared with PE; no differences were observed after MB. There were no significant changes in HR to AVP or PE after GB, thus indicating a lack of a direct effect of these agents on the HR. Our results show that MB and GB equally potentiate the pressor effects of AVP and PE, and the augmentation was much greater for AVP than for PE. The difference in the potentiation of these two vasoconstrictors is consistent with the finding that the baroreflex sensitivity during AVP was enhanced compared with PE. We have postulated that, in the resting conscious dog, AVP increases the sensitivity of the baroreflex primarily by producing a greater level of parasympathetic tone to the heart in response to a given pressure stimulus.

Animals↗