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Biomedical subjects

D Young

Publications and source records attributed to D Young.

At least 577 records · Page 32Linked to original sources
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Tibetan protection from intrauterine growth restriction (IUGR) and reproductive loss at high altitude.

Chronic hypoxia at high altitude restricts fetal growth, reducing birth weight and increasing infant mortality. We asked whether Tibetans, a long-resident high-altitude population, exhibit less altitude-associated intrauterine growth restriction (IUGR) and prenatal or postnatal reproductive loss than Han (ethnic Chinese), a group that has lived there for a shorter period of time. A population sample was obtained, comprising 485 deliveries to Tibetan or Han women over an 18-month period at 8 general hospitals or clinics located at 2,700-4,700 m in the Tibet Autonomous Region, China. Birth weight, gestational age, and other information were recorded for each delivery. Prenatal and postnatal mortality were calculated using information obtained from all pregnancies or babies born to study participants. Tibetan babies weighed more than the Han, averaging 310 g heavier at altitudes 2,700-3,000 m (95% CI = 126, 494 g; P < 0.01) and 530 g heavier at 3,000-3,800 m (210, 750 g; P < 0.01). More Han than Tibetan babies were born prematurely. Prenatal and postnatal mortality rose with increasing elevation and were 3-fold higher across all altitudes in the Han than the Tibetans (P < 0.05). Tibetans experience less altitude-associated IUGR than Han and have lower levels of prenatal and postnatal mortality. When the relationships between birth weight and altitude are compared among these and other high-altitude populations, those living at high altitude the longest have the least altitude-associated IUGR. This may suggest the occurrence of an evolutionary adaptation.

Adult↗
PubMedDate not supplied

Effects of naproxen and nabumetone on serum cholesterol levels in patients with osteoarthritis.

In a 12-week controlled clinical study of the effects of two nonsteroidal anti-inflammatory drug regimens on serum lipoproteins in patients with osteoarthritis, 54 patients were treated with naproxen, 500 mg twice daily, and 45 patients were treated with nabumetone, 1,000 mg once daily. In patients who received naproxen, the mean levels of total serum cholesterol decreased by 18.3 mg/dL (7.0%) from baseline to 12 weeks, high-density lipoprotein (HDL) cholesterol remained unchanged, and low-density lipoprotein (LDL) cholesterol decreased by 15.4 mg/dL (8.7%). In patients who received nabumetone, mean levels of total serum cholesterol increased 10.4 mg/dL (4.0%), HDL cholesterol remained unchanged, and LDL cholesterol increased 7.2 mg/dL (4.1%). Furthermore, serum triglyceride levels tended to increase in nabumetone-treated patients and decrease in naproxen-treated patients, with a statistically significant (P < 0.05) difference between treatments. The decreases in total cholesterol and LDL cholesterol levels in patients receiving naproxen were statistically significant (P < 0.01). These results confirm previous findings on naproxen's cholesterol-lowering effect.

Adult↗
PubMedDate not supplied

Increased responsiveness of hippocampal pyramidal neurons to nicotine in aged, learning-impaired rats.

The effect of aging upon the responsiveness of hippocampal CA1 pyramidal neurons to nicotine was investigated using electrophysiological techniques in male Fischer 344 rats. Prior to electrophysiological recording, animals were behaviorally tested using the Morris water maze. All 3-6 and 18-21 month rats displayed rapid place learning in this task, while none of the 27-30 month animals learned within the 5-day test period. By contrast, rats of all age groups were able to learn a cue version of the water maze task. Following behavioral testing, the animals were anesthetized with sodium pentobarbital for acute recording. Nicotine was locally applied to electrophysiologically identified CA1 pyramidal neurons using pressure microejection from two-barreled glass microelectrodes. For each neuron, a dose of nicotine was found which elicited a 300-400% increase in basal firing rate. These data were used to construct cumulative dose response curves for populations of neurons tested in 3-6-, 18-21-, and 27-30-month-old animals. An age-related increase in the responsiveness of CA1 pyramidal neurons to locally applied nicotine was observed. The results of this study suggest that an increase in hippocampal CA1 pyramidal cell responsiveness to nicotine could be related to the impaired place learning ability seen with aging.

Action Potentials↗
PubMedDate not supplied

Improving caretakers' knowledge of fever management in preschool children: is it possible?

INTRODUCTION: The purpose of this study was to investigate caretakers' knowledge of the implications of fever, the appropriate method of fever management, and the effectiveness of an educational intervention directed toward improving caretakers' ability to manage their child's fever. METHOD: A descriptive, comparative study was conducted with a convenience sample of 86 caretakers. Follow-up data were obtained for 50 caretakers. Data were collected with an investigator-developed open-ended questionnaire. RESULTS: A fever of 104 degrees F was considered to be harmful by 31 subjects. However, fever as low as 100 degrees F was perceived to be harmful by eight subjects. Administration of acetaminophen was the most frequent method of treatment (84 [98%] of 86). No significant improvement in caretaker knowledge in terms of the level of fever at which to administer medication was demonstrated (chi-squared analysis, .012; df, 1; p = 0.91). Accuracy of antipyretic medication dosage was improved (chi-squared analysis, 13.13; df, 6; p = 0.04). DISCUSSION: Caretakers continue to perceive even marginal fevers can cause harm. Improvement was noted in dose accuracy after the intervention. The lack of significant improvement in caretaker knowledge regarding some aspects of fever management after the educational intervention suggests that more than a one-time educational intervention is required.

Acetaminophen↗
PubMedDate not supplied

Biological activity and in vivo clearance of antitumor antibody/cytokine fusion proteins.

Several human cytokines including IL-2, GM-CSF, and tumor necrosis factors alpha and beta were engineered as fusion proteins to the carboxyl terminus of a chimeric anti-ganglioside antibody, ch14.18, and expressed in transfected hybridoma cells. All of the fusion proteins were expressed at high levels and were easily purified by affinity or ion-exchange chromatography from culture supernatants. The effect of fusion on antigen binding activity was tested and found to vary with the particular cytokine. No significant decreases in antigen binding were observed, and fusion of IL-2 had the greatest positive effect in a direct antigen binding assay. All fusion proteins maintained normal levels of biological activity except for GM-CSF, which was approximately 20% active, compared to recombinant GM-CSF produced in bacteria. The clearance of the fusion proteins was examined in normal Balb/c mice after intraperitoneal injection or in athymic (nu/nu) mice after intravenous injection and was generally quite rapid, relative to ch14.18. This was mainly due to a very rapid initial clearance rate (alpha phase) since the half-lives of the beta phase of the fusion proteins (about 30 h) were comparable to that of the free antibody (about 58 h). These results demonstrate that biologically active antibody/cytokine fusion proteins can be constructed by genetic engineering. Their relatively rapid clearance may require constant infusion rather than bolus injection in order to achieve clinical efficacy.

Animals↗