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Biomedical subjects

P Chalmers

Publications and source records attributed to P Chalmers.

13 recordsLinked to original sources
PubMed2002

Performance on tests of frontal lobe function reflect general intellectual ability.

Recent studies have indicated that performance on tests of frontal lobe function are highly associated with general intellectual ability (g). Some authors have even claimed that the available evidence does not support a more specific account of frontal lobe function than to provide a general intellectual function for the performance of goal directed tasks. We examined the relationship between performance on the WAIS-R (as a measure of g) and performance on standard tests of frontal lobe function in 123 healthy individuals. Our results demonstrate that in healthy individuals (i) performance on the most popular tests of frontal lobe function shares significant variance, and (ii) a large proportion of that shared variance is highly associated with performance on the Wechsler Adult Intelligence Scales-Revised (WAIS-R), so that the tests are similar to the extent that they measure g. Performance on the Modified Card Sorting Test (MCST), however, is not related to g. The results support the claim that many tests of frontal lobe function measure primarily a non-specific intellectual function but also indicate that some tests, like the MCST, may be assessing more specific cognitive operations.

Adolescent↗
PubMed2000

Hypoxia depresses nitric oxide output in the human nasal airways.

OBJECTIVES: The role of oxygen in the nasal air on nasal nitric oxide (NO) output was studied in 13 adult volunteers. METHODS: Nasal NO was measured while air containing oxygen (0%-100% in nitrogen) was aspirated through the nasal airway before and after the topical application of xylometazoline. RESULTS: The mean nasal NO output of the untreated nose was 507.8 +/- 161.9 nL/min (mean +/- SD) when 21% oxygen was aspirated through the nasal cavities in series and remained unaltered by 100% O2 (P = .79). Below 10% oxygen the reduction in nasal NO output correlated positively and significantly with the decrease in oxygen concentration (r2 = 0.14). NO output was 245.2 +/- 153.4 nL/min at 0% oxygen, a significant decline from 21% oxygen (P < .0001). Nasal vasoconstriction induced by xylometazoline and alterations in the blood oxygen content by a maximal breath-holding or breathing 100% oxygen did not alter nasal NO in hypoxia (P = .41). CONCLUSIONS: Nasal NO output is markedly depressed in hypoxia and is oxygen dependent at concentrations of less than 10%. Approximately 50% of nasally generated NO is produced from oxygen in nasal air or regulated by it.

Administration, Topical↗
PubMed1999

Performance on the Modified Card Sorting Test by normal, healthy individuals: relationship to general intellectual ability and demographic variables.

OBJECTIVES: The aim of this study was to obtain normative data for the Modified Card Sorting Test (MCST), and to examine the relationship between performance on this task, general intellectual ability and demographic variables. DESIGN: A sample of 146 healthy individuals was tested with a demographic distribution (age, sex, socioeconomic class) similar to that of the British population. METHODS: The MCST and the Wechsler Adult Intelligence Scales--Revised were administered to 146 people aged between 16 and 75 years. RESULTS: Most people (56.6%) completed six categories, and many people made perseverative errors. Approximately 8% of the participants made over 50% perseverative errors. Performance on the MCST varied with age, years of education and general intellectual ability. Individuals with a Full Scale Intelligence Quotient (FSIQ) below 100 showed much more variability in performance than individuals with an FSIQ over 100. Detailed percentile norms for the performance on different indices of the test are presented. CONCLUSIONS: The performance of individuals on the MCST is more closely associated with general intellectual ability than with demographic variables.

Adolescent↗
PubMed1996

Group aggregates and individual reliability: the case of verbal short-term memory.

Two experiments examined the generalizability of the effects of word length and phonological similarity with visual and auditory presentation in immediate verbal serial ordered recall. In Experiment 1, data were collected from 251 adult volunteers drawn from a broad cross-section of the normal population. Word length and phonological similarity in both presentation modes significantly influenced the group means. However, 43% of the subjects failed to show at least one of the effects, and the likelihood that effects appeared was highly correlated with verbal memory span. In Experiment 2, 40 subjects of the original sample were retested, 20 of whom had failed to show one or more effects in Experiment 1. Whether or not an effect had appeared for individual subjects on the first test session was a poor predictor of whether the effect would appear on retest. Finally, an analysis of subject reports demonstrated that the patterns of experimental data could be accounted for in part by the strategies that subjects reported using, and the effect of strategy was independent of the effect of span. The implications of these findings for theories of verbal short-term memory are discussed.

Acoustic Stimulation↗
PubMed1986

Comparison of sonotubometry with tympanometry to assess eustachian tube function in adults.

Eustachian tube dysfunction is thought to be one of the most important factors in the development of middle ear effusions. Direct measurement of Eustachian tube opening is not widespread in clinical practice. Evaluation of a new, small and cheap sonotubometer was carried out on 50 volunteers. The results were compared with the measurement of Eustachian tube function by tympanometry and show a high degree of correlation (P less than 0.001).

Acoustic Impedance Tests↗
PubMed1984

Oral bromazepam in premedication. A comparison with diazepam.

Bromazepam, a relatively newly benzodiazepine with marked anxiolytic effects, was compared in a randomised, double-blind manner with diazepam for its effectiveness as an oral premedicant drug. A scoring system was used to assess sedation, relief of anxiety, nausea, and cardiovascular effects in two groups of women having gynaecological operations. No difference was demonstrated between the effectiveness of the two drugs.

Administration, Oral↗
PubMed1980

Field outbreaks of hyperoestrogenism (vulvo-vaginitis) in pigs consuming maize infected by Fusarium graminearum and contaminated with zearalenone.

During the spring and summer of 1979 field outbreaks of porcine hyperoestrogenism characterized by swelling and reddening of the vulva and teats in prepubertal gilts and enlargement of the mammae in young males occurred in the mistbelt of the Natal Midlands. On a farm in the Ixopo district, pigs were fed a mixed ratio containing home-grown yellow maize stored on the cob in a crib and all the young pigs with a mass of 25-85 kg (=a total of 350) were affected. Maize ears from the crib had a high percentage (91%) of kernels infected by Fusarium graminearum and contained 10 mg/kg of zearalenone. The mixed ration contained 0,95 mg/kg zearalenone. After dilution of the contaminated maize with good quality white maize, a dramatic decrease in both the incidence and severity of clinical signs occurred within 3-4 days. On a farm in the Winterton district, approximately 80% of the growing pigs with a mass of more than 40 kg fed a mixed ration containing shelled yellow maize from the silo of the local Agricultural Co-operative were affected. The incidence as well as the severity of the swelling of the vulvas and/or treats were lower than on the farm at Ixopo, thus indicating a lower level of oestrogen intake. A sample of maize from the silo delivered to this farm contained only 0,06 mg/kg zearalenone while the mixed ration did not contain chemically detectable levels of zearalenone. This is the first published record of field outbreaks of porcine hyperoestrogenism associated with the ingestion of F. graminearum infected maize contaminated with zearalenone in the Republic of South Africa.

Animal Feed↗
PubMed1976

Less common "doping" agents and substances encountered during routine screening for drugs.

The chromatographic and spectroscopic properties of several unusual substances which have been detected in the "alkaloidal" chloroform extract from racehorse urine and saliva samples are reported. Some of these substances have been identified by combined gas chromatography-mass spectrometry and the source of the substance is stated where this is known. Other substances whose identity is not known have been detected and their mass spectra show characteristic amine fragments. The occurrence of these unidentified substances is more frequent in aged urine samples and it would therefore appear that they are associated with putrefaction.

Animals↗