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Biomedical subjects

P Thompson

Publications and source records attributed to P Thompson.

At least 217 records · Page 12Linked to original sources
PubMed1987

Titanium implants in the otic capsule: development of a new multichannel extracochlear implant.

Preliminary data are presented on the development of a new approach for multi-channel stimulation of the cochlea. The approach is based upon the use of small titanium implants in the lateral wall of the inner ear which act as anchor points for platinum-iridium stimulating electrodes. These holders allow contact of the stimulating electrode with the lateral surface of the membranous labyrinth. Observations in monkeys indicate that some degree of anchoring of the titanium implant in the otic capsule is achievable, including the formation of a close bone-metal interface. We propose that this approach may yield an alternative strategy for the development of a multichannel extracochlear prosthesis.

Animals↗
PubMed1986

An assessment of reproductive wastage in sheep.

Reproductive wastage was evaluated by relating ovulation rate to lambs born or raised in range finewool ewes over a ten-year period. The results indicate that reproductive losses are of large magnitude and that these losses are concentrated in the period of ovulation to implantation and in death losses of lambs born. In this study, 33.5% of the potential lamb crop was lost in the early period. Multiple ovulating ewes showed the greatest embryonic loss. The data do not deviate from the binomial distribution, thus suggesting that these losses are largely due to chance. Further work is indicated in the first seventeen days after ovulation to examine losses due to fertilization failure, chromosomal abnormalities, and implantation failure. Abortion or absorption of the fetus was indicated in only 4% of the ewes sampled. An average of 16% of the potential lamb crop was lost from birth to weaning, with 73% of these losses occurring in the first few weeks. Management practices need to be developed to reduce these losses, and these would be expected to vary from one producer to the next depending on conditions. Increasing ovulation rate is one possible method of improving reproductive efficiency, as results of this study indicate that for each unit increase in ovulation rate, there is an increase of 0.52, 0.46, 0.33, and 0.23 in the average number of embryos surviving, lambs born, lambs marked and lambs weaned, respectively.

Journal Article↗
PubMed1986

Surface alterations in dialysis roller pump inserts: a scanning electron microscopy study.

Scanning electron microscopy has been used in a study of particle spalling from silicone and PVC elastomer inserts of dialysis roller pumps. In an experimental circuit using Isoton II, pump occlusion, pressure, pump revolutions and temperature were monitored. Scanning electron microscopy was performed on inserts exposed to 1-10 h of pumping using Silastic (medical grade) and a Watson-Marlow MHRE pump, with PVC and Pivipol, a polyurethane coated PVC (Bellco) using a Bellco BL705N pump. Changes included longitudinal splits (single and multiple), superficial cracks (random and orientated), deformations of normal surface pattern, holes, craters and detaching particles. There was an increase in these abnormalities with time for all types of pump insert, the changes being most marked for the Silastic/Watson-Marlow pump combination and least prevalent with the PVC/Bellco pump combination.

Humans↗
PubMed1986

Zinc status and sexual development in adolescent girls.

Forty-eight black adolescent girls, aged 8 to 16, from the inner city of Baltimore were divided into five groups according to breast and pubic hair development. Blood and hair zinc concentrations as analyzed by atomic absorption spectrophotometry were within ranges reported by other investigators. Hair zinc levels significantly increased (p less than .05) from the second to the last stage of puberty and were significantly correlated (p less than .05) with erythrocyte zinc levels, height, and weight. Mean dietary intakes of calories and protein, as measured from a 24-hour recall, were adequate and increased with stage of breast and pubic hair development. Mean zinc intakes reported in the 24-hour recall averaged 66% of the RDA in the latter half of puberty. It appeared that zinc nutriture was generally adequate in this population, even though the dietary intake of zinc was below the recommended level.

Adolescent↗
PubMed1986

Photosensitization of leukemia L1210 cells with diaziquone.

Exposure of leukemia L1210 cells in culture to the drug diaziquone resulted in inhibition of incorporation of labeled thymidine into nucleic acid and loss of cell viability. These effects were markedly potentiated by irradiation of cells previously exposed to diaziquone in culture. This result shows that diaziquone can catalyze phototoxicity; the action spectrum of the drug may limit clinical applications of this phenomenon.

Animals↗
PubMed1986

The use of seclusion in psychiatric hospitals in the Newcastle area.

Between 1981 and 1984, the frequency with which seclusion was used decreased in Newcastle. Secluded patients were younger, more often male, unmarried, unemployed, and admitted formally, and there was an association with certain diagnoses. Most seclusions occurred early in the hospital stay, mainly in the daytime, especially at mealtimes, and first seclusions were the longest. Violent incidents were usually associated with non-psychotic patients, and staff were the commonest victims. Medication used was major tranquillisers or paraldehyde.

Adult↗
PubMed1985

The effect of vitamin A supplementation on serum retinol and retinol binding protein levels.

A randomised double blind controlled trial was conducted to see whether vitamin A supplementation in the form of retinyl palmitate would increase the concentrations of serum retinol and retinol binding protein. A total of 376 people were studied and were allocated to one of 7 regimens covering doses of vitamin A from O (placebo) to 36,000 IU daily. Supplementation continued for 6 months and blood samples were collected immediately before the start of supplementation, after 3 months and after 6 months. There was a small but statistically significant increase in serum retinol levels associated with supplementation, but no significant increase in serum retinol binding protein. The extent of the increase in serum retinol was related to the extent of the supplementation. On average, for every 10,000 IU of retinyl palmitate per day, the serum retinol concentration increased by 13 micrograms/l after 3 months (an increase of 2%) and 12 micrograms/l after 6 months of supplementation (2% increase). All the regimens used showed no evidence of toxicity other than minor symptomatic and physical changes affecting the skin and mucous membranes.

Adult↗
PubMed1985

Setting and counselor type as related to program retention.

Study was made of the relationship between successful treatment outcome and staff:client ratios in two types of treatment settings. Successful treatment was defined as retention in treatment for at least 6 months and program completion. Using a total sample of 5,405 discharged clients, it was found that there were no differences in outcome between community mental health centers and dedicated drug abuse treatment programs for clients whose primary drug of abuse was either an opiate or a nonopiate exclusive of marijuana. Community mental health centers were significantly more likely to retain minority group marijuana clients 6 months or more to treatment completion while dedicated drug abuse programs were significantly more likely to retain White marijuana clients 6 months or more to treatment completion. No differences in outcome were found for any of the three client groups in relation to program emphasis on advanced-degreed professionals as compared to paraprofessionals.

Community Mental Health Centers↗
PubMed1985

Minority group status and treatment retention.

Study was made of the extent to which majority/minority status within program was associated with treatment outcome. Examining situations in which Blacks, Mexican-Americans, and Whites constituted significant majorities or minorities within each of three treatment modalities, it was found that minority status had particular relevance for treatment retention and for type of discharge in drug-free outpatient programs. Minority status was less significant to treatment outcome in methadone maintenance and residential programming. Several hypotheses are offered to explain the greater significance of race/ethnic issues for outpatient drug-free programming.

Black or African American↗
PubMed1984

Phosphorylation of ovine rhodopsin. Identification of the phosphorylated sites.

Light-dependent phosphorylation of sheep opsin was obtained in purified discs to which was added a partially purified preparation of rhodopsin kinase. A maximum ratio of 1.8 mol of phosphate/mol of rhodopsin bleached was obtained. Perturbing the lipid bilayer did not alter the phosphorylation ratio. Dephosphorylation in both segments and discs was only achieved when the supernatant fraction from a retina homogenate was added. Complete dephosphorylation required the presence of the detergent dodecyltrimethylammonium bromide in the incubation medium. Treatment of phosphorylated disc membranes with Staphylococcal aureus V8 proteinase generated two membrane-bound fragments, only one of which (V8-S, Mr 12 000) was labelled, together with a soluble seven-residue peptide that contained [32P]phosphoserine. Peptide sequencing, together with subdigestion procedures, localized the phosphorylation sites to serine residues at positions 334, 338 and 343 in the whole sequence and threonine residues at positions 335 and 336.

Amino Acid Sequence↗
PubMed1984

Plasma beta-endorphin, pain thresholds and anxiety levels across the human menstrual cycle.

Nine normally cycling women and seven other women employing oral contraception were tested during five phases (menstrual, follicular, ovulatory, luteal and premenstrual) of their menstrual cycle. The procedure consisted of administration of an anxiety inventory and determination of pain detection and pain thresholds in response to electric shock and the cold pressor task. Venipunctures were also performed and the plasma of normally menstruating women later assayed for beta-endorphin. Analyses revealed that the variance but not the mean levels in peripheral beta-endorphin levels significantly differed (p less than 0.01) across the menstrual cycle with the greatest amount of variance found during the ovulatory phase and the least during the luteal phase. The high variance during the period around ovulation was due to several subjects having extremely elevated beta-endorphin levels which possibly may have resulted from the occurrence of ovulation. Furthermore, a significant positive correlation between anxiety levels and beta-endorphin levels was found only during the menstrual phase. The absence of findings concerning cyclic variation in pain thresholds is contrary to earlier reports and indicates that such a phenomenon may be dependent upon the paradigm employed.

Adult↗