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Biomedical subjects

N C Smith

Publications and source records attributed to N C Smith.

At least 91 records · Page 5Linked to original sources
PubMed1989

The role of free oxygen radicals in the expulsion of primary infections of Nippostrongylus brasiliensis.

The many and varied pathological, immunological and physiological manifestations of infection with Nippostrongylus brasiliensis may be unified by considering the role of leukocyte-generated free oxygen radicals in worm expulsion. Aside from directly damaging the adult stage of N.brasiliensis and possibly leading to its elimination from the small intestine, free radicals may also damage intestinal cells, thereby contributing to the gut pathology characteristic of infection. gamma-Interferon (and possibly tumour necrosis factor) may be involved in the initiation of free radical generation in response to N. brasiliensis and may also contribute to various side effects of infection such as hypertriglyceridaemia and cachexia. gamma-Interferon may initiate free radical generation via the agency of protein kinase C, an enzyme that can induce various additional responses including lysosomal enzyme and amine secretion and arachidonic acid metabolism. The possible interactions between these mediators and free radicals are subtle and diverse and may profoundly affect the course of infection.

Animals↗
PubMed1989

Free radical generation during primary infections with Nippostrongylus brasiliensis.

The production of free radicals during infection of the rat with Nippostrongylus brasiliensis was investigated. Lipid peroxidation, which is the best documented effect of free radicals, was monitored in the small intestines of infected rats by measurement of malonyldialdehyde and was found to be increased at the time of worm rejection. The capacity of peritoneal leucocytes to produce free radicals, as measured by chemiluminescence, was monitored in rats infected with different doses of N. brasiliensis. Rejection of N. brasiliensis from rats infected with 6000 third-stage larvae (L3) began 2 days earlier than in rats infected with only 600 L3. Maximal free radical generation also occurred 2 days earlier and was quantitatively greater in rats infected with 6000 L3. Free radical generation by leucocytes in response to live adult N. brasiliensis was enhanced by plasma from infected rats indicating the existence of a plasma-borne factor responsible for the initiation of free radical generation in response to N. brasiliensis.

Animals↗
PubMed1989

The effect of antioxidants on the rejection of Nippostrongylus brasiliensis.

The effect of the antioxidants, butylated hydroxy anisole (BHA) and vitamin E, on the rejection of Nippostrongylus brasiliensis from the small intestine of the rat was investigated. Worm expulsion was inhibited by BHA. Malonyldialdehyde production in the small intestines and free radical generation by peritoneal leucocytes from infected rats were also inhibited by BHA. Vitamin E, although inhibiting malonyldialdehyde production, did not prevent worm expulsion. Significantly, vitamin E was much less effective than BHA at reducing free radical generation by rat leucocytes in response to N. brasiliensis.

Animals↗
PubMed1988

Precompetitive anxiety and motor performance: a psychophysiological examination.

Male volunteer subjects (27) completed a 5-week habituation period during which practise was undertaken on three motor performance tests. Tests were of serial reaction time, visuomotor ability and muscular power. Following stabilization of performance subjects entered an experimental period where they performed the tests before an evaluative audience on one occasion, and against a matched opponent, also before an evaluative audience on the final occasion. Preperformance measures were obtained of neuroendocrine activity, anticipatory heart rate and state anxiety. Significant precompetition elevations in state anxiety, heart rate and adrenaline levels were observed, supporting the notion that the exposure was perceived as stressful by subjects. Significant correlations were obtained between adrenaline levels and both state and trait anxiety scores. Results showed a significant increase in performance compared to habituation levels for all three tests in the audience condition. In the competitive situation against a matched opponent, performance level for the visuomotor and power tests declined significantly compared to the previous session performed before an audience. Serial reaction time performance showed a continuing upward trend, although failing to achieve significance. Changes in performance are discussed with reference to cue-utilization explanations and broader cognitive resource limitations.

Adolescent↗
PubMed1987

Preliminary report on a prepregnancy counselling clinic.

Although prepregnancy counselling is given within the health service at various clinics there remains a need for patients with specific medical and obstetric problems to receive specialist advice. An analysis of the first 200 patients referred to a prepregnancy counselling clinic is given here to outline the function of such a service.

Abortion, Spontaneous↗
PubMed1986

Perinatally related wastage--a proposed classification of primary obstetric factors.

Adapting Sir Dugald Baird's concept of primary obstetric causes of perinatal mortality, a revised clinico-pathological classification has been evolved to take account of new knowledge and developments, and to direct attention to potentially avoidable deaths and to where intensified efforts and investigation are needed. Categories highlighting the importance of intrauterine growth retardation, unexplained intrauterine death and spontaneous premature labour have been introduced, intrapartum hypoxia is separated from birth trauma, and infection again has its own category. Regular perinatal audit at one obstetric hospital, since 1979, has shown that the new system provides a workable and useful means for classifying not only perinatal deaths, but also late abortions, late neonatal deaths and perinatally related infant deaths. The rate of total perinatally related wastage, defined in this way, was almost twice that for perinatal mortality (22.8 compared with 11.9 per 1000 births). The former is advocated as a more realistic index for the audit of perinatal care. The revised and extended system is put forward as a contribution to the current debate on classifying and reporting such wastage, in the hope that it may be tested as a model for regional as well as hospital surveys.

Birth Injuries↗
PubMed1983

Coital injuries of the vagina in non-virginal patients.

A series of 19 non-virginal patients who sustained vaginal injuries during normal coitus is presented. Twelve were between 16 and 25 years of age and 5 were older than 45 years. All presented with profuse or prolonged vaginal bleeding. The initial diagnosis was frequently wrong because a history of injury was not forthcoming and visualization of the lesion was obscured by the bleeding. The possibility of such trauma should be kept in mind; digital examination confirms the diagnosis. Prompt surgical suturing under general anaesthesia is required to control the haemorrhage.

Adolescent↗
PubMed1983

Fetal scalp blood lactate as an indicator of intrapartum hypoxia.

Fetal scalp blood lactate was measured during labour by a simple, rapid method and its value as an indicator of fetal intrauterine hypoxia was assessed and compared with that of pH measurement. The normal ranges of lactate concentration and of pH values were calculated. Significantly higher concentrations of lactate and lower pH values were found in samples of scalp blood taken close to delivery from babies with Apgar scores of less than or equal to 6 at 1 min compared with those from healthy babies with Apgar scores of greater than or equal to 7 at 1 min. A similarly significant difference was observed between the cord blood lactate and pH values of these two groups of babies. Ominous fetal heart rate patterns were associated with higher lactate concentrations and lower pH values in fetal scalp blood than were normal fetal heart rate patterns. The measurement of fetal scalp blood lactate or pH, or continuous electronic fetal heart rate monitoring were equally good at predicting the condition of the infant at birth.

Apgar Score↗
PubMed1983

The role of microsomal enzyme inducers in the reduction of misonidazole neurotoxicity.

In a series of studies, we have shown that phenytoin, 300 mg daily for one week, produces consistent hepatic microsomal enzyme induction, resulting in a decrease of 25% in misonidazole half-life, without causing any toxicity per se. A longer period of administration gives only a slightly greater induction. Phenobarbitone in a daily dose of 90 mg causes a reduction of 18% and 23% in misonidazole half-life after 1 and 2 weeks' pre-treatment respectively, but is less suitable clinically because of its sedative effect. A further series of studies using phenytoin as the inducing agent has shown that, despite adequate enzyme induction and increased misonidazole metabolism, it is impossible to increase the total dose of misonidazole beyond the usually accepted value of 12 g/m2 because of unacceptable neuropathy (a rate of 50% at a dose of 14 g/m2 over three weeks). In single doses of above 3.0-4.0 g of misonidazole, severe nausea and vomiting are prominent, so that this side effect is a determining factor in the treatment fractionation. Audiometric studies show no correlation between the incidence of peripheral neuropathy and abnormal audiograms, and have no value in the early prediction of neurotoxicity. It seems that despite causing increased metabolism, enzyme induction does not protect against neurotoxicity and thus will not permit the use of higher doses of misonidazole for increased radiosensitisation.

Adult↗
PubMed1979

Rapid whole blood lactate measurement in the fetus and mother during labour.

Using a new rapid method, fetal and maternal whole blood lactate was measured before the onset of labour at elective Caesarean section in 8 patients, during labour in 34 normal patients, and in a further 28 patients whose babies showed varying degrees of clinical depression and/or acid base abnormality at birth. The mean (+/- SEM) umbilical venous and arterial and maternal venous lactate values in the 8 cases delivered by elective Caesarean section were 1.20 (+/- 0.16), 1.46 (+/- 0.22) and 1.14 (+/- 0.46) mmol/l, respectively. For the normal group the mean fetal lactates (+/- SEM) in the latent and active phases of labour, and in the umbilical vein and artery, were 1.91 (+/- 0.25), 2.42 (+/- 0.46), 2.71 (+/- 0.19) and 3.09 (+/- 0.20) mmol/l, respectively. The mean maternal venous lactate (+/- SEM) in the latent and active phases of labour and at delivery were 1.07 (+/- 0.09), 1.45 (+/- 0.12) and 2.69 (+/- 0.24) mmol/l. the rise in fetal lactate throughout labour was due in part to the rise in maternal lactate. Increasing neonatal depression was associated with increasing fetal lacticacidaemia. This associationachieved statistical significance at delivery.

Cesarean Section↗
PubMed1978

Preparation and characterization of human syncytiotrophoblast plasma membrane.

On the basis of electron microscopic evidence, a preparation of microvilli obtained from the surfaces of placental villi was previously considered by us to represent syncytiotrophoplast plasma membrane. The present investigation was undertaken to obtain independent biochemical evidence on the nature of the preparation. Protein, lipid, carbohydrate, sialic acid, phospholipid and cholesterol concentration were determined and found to be consistent with analyses of membranes obtained from other sources. Enzyme membrane markers (5'-nucleotidase, (Na+ + K+)-ATPase and alkaline phosphatase) were also assayed, and found to be considerably enriched in the microvillous preparation compared to the whole placental homogenate. These findings, together with other evidence, support the contention that the preparation is indeed syncytiotrophoblast plasma membrane.

Adenosine Triphosphatases↗
PubMed1976

The radiological demonstraction of colorectal polyps undetected by endoscopy.

In a consecutive series of 800 routine double contrast studies of the colon, 119 polyps were diagnosed radiologically in 78 patients. Follow-up studies were available in 46 patients with 72 polyps. Ultimately, 56 of these polyps were confirmed (55 by endoscopy and 1 by repeat radiology). Six of these polyps had been missed on the initial endoscopic examination. The missed polyps are usually located in the rectum behind a valve of Houston or in any area of the colon where there is sharp angulation. Radiologists and endoscopists should be aware of these as potential endoscopic blind spots. These cases illustrate the importance of higg quality radiological study of the colon and the complementary nature of radiology and endoscopy in the detection of colorectal polyps.

Adult↗