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Biomedical subjects

I Smith

Publications and source records attributed to I Smith.

At least 361 records · Page 20Linked to original sources

Cancrum oris.

Cancrum oris is a gangrenous infection of the oral cavity. Debilitating diseases predispose to the condition. The exact bacteriology is uncertain although Vincent's Spirochaete and the fusiform bacillus in symbiosis have been considered to be the actual cause of the condition. The presentation of the disease is variable, for the condition may affect the soft tissues of the face or the bones of the facial skeleton or both concurrently. This disease has a high mortality rate. If recovery from toxaemia ensues, subsequent healing becomes a lengthy affair because of the destructive nature of the condition. Since the introduction of antibiotics as a form of therapy, a higher survival rate has been achieved. Because of the nature of the condition the morbidity rate is exceptionally high with functional disturbances and disfigurement being a legacy of the disease. Reconstructive procedures are generally required at some subsequent stage.

Humans↗

Behavioural deviance in children with early treated phenylketonuria.

A sample of 99 early treated phenylketonuric children showed higher levels of behavioural deviance than 197 matched controls. For boys this excess of behavioural deviance persisted when IQ was taken into account. For phenylketonuric girls however it was restricted to those with IQs less than 70. The type of behavioural deviance shown by the boys over the whole IQ range was predominantly neurotic. The levels of behavioural deviance found in phenylketonuric children were among the highest that have been reported for children with various handicapping conditions.

Adolescent↗

A sensitive and specific assay for 5-methoxytryptophol in plasma.

5-Methoxytryptophol (ML) is found in the pineal gland and is known to have biological activity especially as an antigonadotrophic agent, but methods have been lacking for its measurement in the circulation. A gas chromatography-mass spectrometry assay using a trimethylsilyl derivative has been developed for the routine measurement of ML in plasma. The assay is of great specificity and has a sensitivity of 20 pmol/l. Studies on the levels of pineal indoles in the circulation, however, have been hampered by the possibility that extraneous compounds are being cross-measured. Thus the specificity of the routine assay has been further validated by comparing it with an alternative assay system where all the major parameters were changed, i.e. derivatizing reagent, internal standard and mass number. Results that were obtained using both assay systems were closely comparable.

Chromatography, Gas↗

Changes in the concentration of 5-methoxytryptophol in the circulation at different phases of the human menstrual cycle.

The pineal indole 5-methoxytryptophol (ML) has been shown to have an antigonadal activity when administered to experimental animals, but data on its normal pattern of secretion have been lacking. Using a new gas chromatography-mass spectrometry assay, the concentration of ML at various phases of the human menstrual cycle has been studied. Daily samples were obtained throughout the month from five women with a normal cycle and two women taking an oral contraceptive. In women with a normal cycle levels of ML were found to be significantly lower in the last third of their cycle; this change was not seen in women taking an oral contraceptive who had low levels throughout the month. The changes in concentration of ML did not correlate with the changes in concentration of gonadotrophins.

Adult↗

Immediate response of 5-methoxytryptophol in the circulation to hypoglycaemic stress induced by insulin.

Pineal indoles have been shown to affect the release of anterior pituitary hormones but details of the interrelationships are lacking. Using a new gas chromatography-mass spectrometry (g.c.-m.s.) assay the concentration of 5-methoxytryptophol (ML) was measured in plasma samples obtained from 16 children undergoing investigation of pituitary function for delayed growth. All the children received an insulin tolerance test (ITT) to study their endocrine response to stress. Some children received luteinizing hormone releasing hormone (LH-RH) and/or thyrotrophin releasing hormone (TRH). The change in concentration of ML during an ITT was similar to the change in concentration of blood sugar; a drop at 20 min followed by a rise at 30 min. This was not significantly altered by the administration of LH-RH or TRH, nor was there a different pattern of response in children who were deficient in growth hormone as opposed to those with idiopathic delayed growth. The fall in concentration of ML with stress may mediate the increased secretion of pituitary hormones. Alternatively, the pineal gland may respond directly to insulin.

Adolescent↗

Concentration of 5-methoxytryptophol in pineal gland and plasma of the rat.

5-Methoxytryptophol, a serotonin metabolite, was measured by gas chromatography-mass spectrometry in pineal glands, plasma and control tissues (cerebral cortex and salivary glands) from male rats kept in a controlled lighting environment. In the pineal gland the level of 5-methoxytryptophol was significantly higher during the dark period than during the light, the absolute levels being an order of magnitude less than those of melatonin. In the plasma, the levels showed a reverse situation with respect to lighting conditions. No correlation was found between the 5-methoxytryptophol levels in plasma and the pineal gland in individual animals. These results suggest that there is no obvious correlation between pineal content and pineal activity. This may be due to a combination of rapid turnover, secretion and/or peripheral conversion of another 5-methoxyindole to 5-methoxytryptophol.

Animals↗

Effect of stopping low-phenylalanine diet on intellectual progress of children with phenylketonuria.

Forty-seven patients at the Hospital for Sick Children, London, who had phenylketonuria and were on a low-phenylalanine diet (21 early-treated--that is, treatment started before the age of 4 months--and 26 late-treated) were placed on a normal diet between the ages of 5 and 15 years. They showed significant falls in mean IQ of about six points after the diet was withdrawn. Twenty-two similar patients (five early-treated and 17 late-treated) at the Universitäts-Kinderklinik, Heidelberg, who were placed on a relaxed low-phenylalanine rather than a normal diet, showed smaller and non-significant falls in mean IQ. During the period of strict diet none of the patients in London or Heidelberg showed any consistent falls in IQ. These results suggest that complete withdrawal of the low-phenylalanine diet during childhood leads to a fall in intellectual progress in many patients.

Adolescent↗