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Biomedical subjects

K Connor

Publications and source records attributed to K Connor.

50 records · Page 3Linked to original sources

Effects of age and diet on the lipid content and composition of gallbladder bile, liver and serum in laying strains of hen.

1. Changes in lipid content and composition of liver and bile during pre- and post-laying periods were investigated in hens of a laying strain. 2. The large increase in liver lipid concentration, particularly triacylglycerols, at the onset of laying was accompanied by the appearance of triacylglycerols in the bile. 3. Accumulation of triacylglycerol in the liver was increased by a diet containing maize and soyabean meal. This was associated with increases in the triacylglycerol concentration in both serum and bile. 4. Liver microsomal phosphatidate phosphohydrolase activity was positively correlated with liver triacylglycerol content in birds given the maize/soyabean meal diet. 5. The time course of triacylglycerol accumulation in the liver and associated changes in the bile triacylglycerol concentration in laying strain hens were different to those previously observed in broiler hens. 6. Over the lifetime of the bird, secretion of triacylglycerols into bile may play an important role in the prevention of fatty liver syndromes.

Aging↗

Changes in the lipid metabolism of the chick embryo with parental age.

A study has been made on the distribution and composition of the lipids associated with the yolk contents, yolk sac membrane, liver, and extrahepatic tissues of chick embryos at Days 15 and 19 of incubation from 25- and 41-week-old broiler-breeder stock. The higher embryo mortality displayed by the eggs from the young breeders was associated with an abnormal distribution of lipid between the tissue pools. The amount of lipid associated with the total yolk, i.e., yolk contents plus yolk sac membrane, of the embryos from the 25-week-old parents at Day 19 of incubation was greater than that of the embryos from the 41-week-old parents, and there was a much higher proportion of lipid still remaining in association with the yolk contents. In the embryos from the young parents, a smaller proportion of embryonic lipid was associated with the extra-hepatic tissues at Day 19 of incubation. Differences were observed in the relative proportions of the major lipid fractions within the yolk and embryonic tissues between the eggs from the two sets of parents. The higher mortality of the embryos from the young parents was associated with a malfunction of yolk lipid assimilation and mobilization from the yolk contents thereby denying access to the major nutrient associated with development during the last week of incubation.

Age Factors↗

The role of defensiveness in cognitive impulsivity.

The role of anxiety in reflection-impulsivity has been a source of controversy, with impulsives portrayed as unanxious by some researchers and as extremely anxious by others. Defensiveness may account for these seemingly contradictory results. Impulsives may present a facade of unconcern to mask underlying anxiety. The impulsive response itself may occur in part because impulsives are defensive about appearing incompetent. Equating rapidity of response with competence, they respond quickly to appear competent. 120 children, with a mean age of 9 years, 7 months, served as subjects. Measurements of defensiveness and impulsivity were examined. Correlations were examined separately by sex since previous research showed that defensiveness correlated negatively with problem-solving success for boys only. Defensiveness and impulsivity were positively correlated for boys only. Unlike previous studies, test anxiety correlated positively with impulsivity for girls.

Anxiety↗

A unique lipid pattern associated with the gall bladder bile of the chick embryo.

A study has been made of the lipid and fatty acid composition of the gall bladder bile of the chick embryo during the last week of incubation. The lipids and their fatty acid composition showed a unique pattern when compared to other animal species. Of the total lipid present, phospholipid accounted for less than half, and there were substantial proportions of both cholesteryl ester and triglyceride. In the cholesteryl ester, the proportion of which increased significantly over the last week of incubation, there was a very high level of oleic acid. The phospholipid contained a high level of arachidonic acid. The results are discussed in relation to observations on the biliary lipids of other animal species and the major features of the lipid metabolism of the chick embryo during the last week of incubation.

Animals↗

The synthesis and accumulation of cholesteryl esters by the developing embryo of the domestic fowl.

A comparative study has been made of the accumulation and synthesis of cholesteryl esters in the liver, yolk sac membrane, and yolk contents of the chick embryo during the last week of development. This involved a comparison of the cholesteryl esters synthesized during incubation in vitro with 14C-cholesterol with those accumulated during incubation in vivo. Results indicated that the considerable accumulation of cholesteryl esters, mainly cholesteryl oleate, that occurred within the liver during embryo development arose from synthesis in the yolk sac membrane. This suggested a specific role in the transport of yolk lipid into the embryo. With the approach of hatching the ability of the liver to synthesize its own cholesteryl esters increased while that of the yolk sac membrane decreased.

Animals↗

Mode of action of phosphonoformate as an anti-herpes simplex virus agent.

Phosphonoformate inhibited the replication of Herpes simplex virus (HSV) type 1 and type 2 in culture. The concentration required to inhibit the replication of both types of virus by 2 logs at 28 h post-infection was approximately 150 microM. It was more potent than phosphonoacetate against the growth of both virus types. A virus mutant which is resistant to phosphonoacetate was cross-resistant to phosphonoformate. Arsonoacetate, at 300 microM, had no antivirus activity. Phosphonoformate also inhibited HeLa and KB cell growth; at a concentration of about 500 microM, cell growth was inhibited by 50%. The anti-cell growth effects of the drug were completely reversible. The antivirus effect of phosphonoformate was partially reversible, depending on the time and duration of exposure of infected cultures to the drug. To obtain the maximum antivirus effect, phosphonoformate had to be added within the first 3 h post-virus-infection and be continuously present for at least 18 h. Phosphonoformate, added at 0 h post-infection, suppressed the induction of virus-specific DNA polymerase and DNAase activities. dTMP incorporation into DNA was preferentially inhibited in nuclei isolated from infected cells compared to uninfected cells, and the degree of inhibition varied with the ionic strength of the assay. Phosphonoformate was a potent inhibitor of the purified HSV-1 and HSV-2 DNA polymerases, inhibiting DNA polymerase activity by 50% at a concentration of 3 microM and ionic strength of 0.2.

Antiviral Agents↗

Understanding visual metaphor: developmental and individual differences.

The development of an instrument--the Metaphoric Triads Task (MTT)--for the assessment of metaphoric comprehension is described. In the tradition of earlier cognitive-style research, a visual triad format was adopted that offered three possible pairings of pictorial stimuli, one of which was metaphorical in character. A subject's score reflects the number of metaphoric pairings formed (with appropriate metaphoric explanations) across all of the triads of the task. Data are reported for 12 samples of subjects (ranging from 7 1/2 to 28 years of age) who responded to the MTT in a diverse array of studies. Internal analyses of the MTT yielded satisfactory reliabilities (interjudge and internal consistency) and item-sum correlations. Sex differences were negligible, but progressive improvement in MTT score with age was noted. At the same time, a slight modification of the MTT triad format generated performance levels from younger children that approximated those of children 1--3 years older who had taken the MTT in its standard form. Higher MTT scores were generally obtained by those subjects who attempted more pairings, spent more time at the task, and chose the metaphoric pair as "best" among the alternative pairing possibilities. Correlations of MTT performance with standardized tests of intellective aptitudes and achievements were inconsistent across samples and between the sexes within samples. In contrast, MTT scores were quite consistently related to solving difficult analogies, generating high-quality responses to divergent-thinking tasks, and manifesting broad categorizing and physiognomic sensitivity. Significant correlations between the MTT and a set of verbal metaphoric triads offered convergent validational evidence suggestive of a general metaphoric style. Some relation was found between MTT performance and teacher ratings of figurative language appreciation and esthetic sensitivity, though it appeared that these might be mediated by the teachers' estimate of the child's overall capability. Finally, three experimental training studies were carried out. A requirement of exhaustive pairing and informative feedback on pretest items significantly enhanced the MTT performance of the younger children. The provision of appropriate verbal labels for each picture in a triad also significantly enhanced performance by insuring that children's encoding of the pictures was consistent with the metaphoric linkage in each item.

Adolescent↗

A beta peptide vaccination prevents memory loss in an animal model of Alzheimer's disease.

Vaccinations with amyloid-beta peptide (A beta) can dramatically reduce amyloid deposition in a transgenic mouse model of Alzheimer's disease. To determine if the vaccinations had deleterious or beneficial functional consequences, we tested eight months of A beta vaccination in a different transgenic model for Alzheimer's disease in which mice develop learning deficits as amyloid accumulates. Here we show that vaccination with A beta protects transgenic mice from the learning and age-related memory deficits that normally occur in this mouse model for Alzheimer's disease. During testing for potential deleterious effects of the vaccine, all mice performed superbly on the radial-arm water-maze test of working memory. Later, at an age when untreated transgenic mice show memory deficits, the A beta-vaccinated transgenic mice showed cognitive performance superior to that of the control transgenic mice and, ultimately, performed as well as nontransgenic mice. The A beta-vaccinated mice also had a partial reduction in amyloid burden at the end of the study. This therapeutic approach may thus prevent and, possibly, treat Alzheimer's dementia.

Aging↗

Animal-assisted therapy: an in-depth look.

Animal-assisted therapy has gained widespread support and application over the past few decades. This article reviews the history of animal-assisted therapy; discusses its present goals and applications, including those pertinent to critical care; and notes questions requiring further research.

Animals↗

Pharmacologic treatment of catheter-related thrombus in pediatrics.

Venous and arterial catheters are being used with increasing frequency in pediatric populations. As part of the comprehensive management of these catheters, nurses need to be aware of the more common catheter-related thrombus problems. An understanding of pharmacologic treatment using Streptokinase and Urokinase for thrombus in central lines, hemodialysis grafts, and umbilical artery catheters can help nurses develop protocols to care for patients with these devices. The appropriate use of thrombolytic therapy can restore function to many catheters thereby saving the patient the cost and morbidity associated with removal and replacement of a dysfunctional catheter.

Catheters, Indwelling↗