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Biomedical subjects

N Bolton

Publications and source records attributed to N Bolton.

At least 19 recordsLinked to original sources
PubMed2000

Measurement of peripapillary retinal nerve fiber layer volume in glaucoma.

PURPOSE: To measure peripapillary retinal nerve fiber layer volume in normal subjects and patients with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma. METHODS: Sixty-five subjects were classified into four groups of normal subjects and subjects with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma on the basis of intraocular pressure measurements, visual field loss, and optic disk appearance. Groups were matched for sex, age, and optic disk area. Peripapillary retinal nerve fiber layer volume measurements were made with a modification of software version 1.11 of the Heidelberg Retina Tomograph confocal scanning laser ophthalmoscope. Retinal nerve fiber layer volume measurements were taken at 0.1-mm increments from the disk margin for a global 360-degree assessment and at four predefined segments using two different reference planes. Statistical analysis was carried out using analysis of variance with Bonferroni correction. RESULTS: Retinal nerve fiber layer volume measurements showed a gradation from normal to ocular hypertension and from ocular hypertension to glaucoma groups. Mean group measurements showed statistically significant differences (P <.05) in peripapillary retinal nerve fiber layer volume for most segmental measures between the groups. Measurements with the default reference plane in the 0.0-mm to 0.1-mm and 0.1-mm to 0.2-mm increments for the superotemporal segment showed the greatest differences between groups (P <.00005). CONCLUSION: Peripapillary retinal nerve fiber layer volume measurements differ between groups of normal subjects and patients with ocular hypertension, primary open-angle glaucoma, and low-tension glaucoma. This measure offers a further method of assessment of retinal nerve fiber layer in patients with glaucoma and glaucoma suspects.

Aged↗
PubMed1990

The rural population turnaround: a case-study of North Devon.

The change from depopulation to population increase in the more remote rural areas of England is analyzed using data from a survey of 300 households in North Devon. The heterogeneous nature of the migrants and their reasons for migration are stressed. "The reasons for leaving the former area of residence tended to relate to lifestyle, personal or environmental factors whereas the reasons for choosing North Devon were more often about jobs and house prices. This complexity and diversity clearly makes difficult the quest for a single theory of the repopulation process."

Behavior↗
PubMed1985

Response of serum testosterone and its precursor steroids, SHBG and CBG to anabolic steroid and testosterone self-administration in man.

The influence of high doses of testosterone and anabolic steroids on testicular endocrine function and on circulating steroid binding proteins, sex hormone binding globulin (SHBG) and cortisol binding globulin (CBG), were investigated in power athletes for 26 weeks of steroid self-administration and for the following 16 weeks after drug withdrawal. Serum testosterone and androstenedione concentrations increased (P less than 0.05) but pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone, 5-androstene-3 beta, 17 beta-diol, progesterone and 17-hydroxyprogesterone concentrations strongly decreased (P less than 0.001) during steroid administration. Serum pregnenolone, 17-hydroxypregnenolone and dehydroepiandrosterone sulphate concentrations followed the changes of the corresponding unconjugated steroids but 5-androstene-3 beta, 17 beta-diol and testosterone sulphate concentrations remained unchanged during the follow-up time. During drug administration SHBG concentrations decreased by about 80 to 90% and remained low even for the 16 weeks following steroid withdrawal. Steroid administration had no influence on serum CBG concentrations. In conclusion, self-administration of testosterone and anabolic steroids soon led to impairment of testicular endocrine function which was characterized by low concentrations of testosterone precursors, high ratios of testosterone to its precursor steroids and low SHBG concentrations. Decreased concentrations of SHBG and testicular steroids were still partly evident during the 16 weeks after drug withdrawal. The depressed circulating levels of dehydroepiandrosterone and its sulphate may indicate that the androgenic-anabolic steroids also suppress adrenal androgen production.

17-alpha-Hydroxypregnenolone↗
PubMed1982

Human testicular LH receptors: correlations with circulating gonadotrophins and testicular steroid secretion.

Testicular androgen production is regulated by circulating LH, the effect of which is mediated by its testicular membrane receptors. In the present study, testicular [125I]hCG binding in man was investigated and found to be characterized by saturability and high affinity (mean KD in testes of 21 patients with prostatic carcinoma = 1.64 X 10(-10) M), and stimulated testosterone production in dispersed interstitial cells in vitro. The concentrations of the LH receptors correlated with serum FSH concentrations (r = 0.52, P less than 0.05) but not with circulating LH levels. Neither had they any correlation with intratesticular testosterone, 5 alpha-dihydrotestosterone, androstenedione, progesterone, 17-hydroxyprogesterone or pregnenolone concentrations, which may be due to the fact that LH receptors are confined to Leydig cells, whereas steroids may be unevenly distributed in the different cells of the testis. In contrast, the concentrations of the LH receptor displayed positive correlations with the concentrations of testosterone (r = 0.81, P less than 0.001), androstenedione (r = 0.54, P less than 0.05), 17-hydroxyprogesterone (r = 0.76, P less than 0.001) and progesterone (r = 0.60, P less than 0.05) in the spermatic vein serum of the patients. Our data suggest that the Leydig cells mainly responsible for steroid secretion into the blood are under gonadotrophic control exerted via their receptors, whereas Leydig cell function is not rapidly reflected in steroid concentrations within the testis itself.

Aged↗
PubMed1982

Versatile semiautomated sample processor and gamma counter to increase radioimmunoassay efficiency.

We describe a semiautomated batch-assay system designed to increase the speed and ease of performing radioimmunoassays while maintaining good accuracy and precision. The main components are a programmable pipetting unit (sample processor) and a gamma counter capable of simultaneously counting radioactivity in 12 samples. The processor uses prearranged sets of as many as 24 disposable pipette tips, which eliminates carryover between samples, and features a horizontal shaker and magnetic stirrer; 50 different assay protocols can be selected. Batches of tubes are easily transferred from the sample processor to the incubator and centrifuge. The gamma counter is controlled by a microprocessor, which is also used for data processing. Because the system is based on discrete rather than continuous-flow analysis and because of the ease with which consecutive samples can be processed, more than one operation and several different assays can be accommodated simultaneously, which saves time considerably.

Estriol↗
PubMed1981

A comparison of the Eysenck Personality Questionnaire and the Psychological Screening Inventory in a delinquent sample and a comparison group.

Administered the Eysenck Personality Questionnaire (EPQ) and Psychological Screening Inventory (PSI) to a group of technical college students (N = 100) who were taking trade training courses. The groups were similar in terms of age and socioeconomic status. A factorial analysis was performed on both of the resulting sets of intercorrelations, and two factors were found to account for over 85% of the variance in each group. The first factor was common to both groups and was labelled neuroticism. While the second factor in the delinquent group clearly could be seen to be extraversion, the second factor in the student group was not interpreted easily, but appeared to be a dimension that represented psychiatric and antisocial problems.

Adolescent↗
PubMed1978

Some psychological, educational and criminological variables related to recidivism in delinquent boys.

The HDHQ, 16 PF and PSI were administered to 315 detainees at Medomsley Detention Centre, Durham, along with tests of intelligence and attainment, and measures of previous criminal history. One hundred and ninety-one boys were subsequently reconvicted within two years of their release. They were found to have lower scores on reading and arithmetic tests, to show a greater degree of extrapunitive hostility and to score more highly on tests of social non-conformity. Recidivists had also begun their criminal careers at an earlier age than non-recidivists and had committed significantly more previous offences.

Achievement↗
PubMed1977

Prisoners' personality: a factor analytically derived structure.

A factor analytic study of personality questionnaire data obtained from a group of 175 long-term prisoners revealed a factor structure which appears to be peculiar to prisoners. In particular, hostility and anxiety obtain prominence in the structure, while the theoretically significant dimension of extraversion is relegated in importance.

Anxiety↗