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Biomedical subjects

N Morton

Publications and source records attributed to N Morton.

10 recordsLinked to original sources
PubMed1992

Transmission of breast cancer--a controversy resolved.

The Danish breast cancer data collected by Jacobsen (1946) have been reanalysed using morbid risks which incorporate mortality due to breast cancer. A dominant gene is favoured for familial breast cancer, supporting the conclusions of Williams & Anderson (1984) and later authors. Neglect of specific mortality does not greatly alter estimates of gene frequency and displacement, but the evidence for a major gene is inflated. No evidence for heterogeneity was found. Earlier claims of non-Mendelian transmission are in error since we have discovered that transmission probabilities are not correctly implemented in the computer program POINTER. Cases with bilateral breast cancer and males with breast cancer all belonged to families favouring a major gene. Of the cancer sites frequently reported to be associated with familial breast cancer, only ovarian cancer is significant in this material.

Breast Neoplasms↗
PubMed1991

Pharmacokinetic model driven infusion of propofol in children.

A computer controlled infusion device for propofol was used to induce and maintain general anaesthesia in 20 children undergoing minor surgical procedures. The device was programmed with an adult pharmacokinetic model for propofol. During and after anaesthesia, blood samples were taken for measurement of propofol concentrations and it was found that the values obtained were systematically overpredicted by the delivery system algorithm. New pharmacokinetic microconstants were derived from our data which reflected more accurately the elimination and distribution of propofol in a prospective study involving another 10 children.

Adult↗
PubMed1991

Von Hippel-Lindau disease: a genetic study.

Genetic aspects of von Hippel-Lindau (VHL) disease were studied in familial and isolated cases. Complex segregation analysis with pointers was performed in 38 kindreds with two or more affected members. Dominant inheritance with almost complete penetrance in the highest age classes (0.96 at 51 to 60 and 0.99 at 61 to 70 years) was confirmed and there was no evidence of heterogeneity between families ascertained through complete and incomplete selection. The point prevalence of heterozygotes in East Anglia was 1.89/100,000 (1/53,000) persons with an estimated birth incidence of 2.73/100,000 (1/36,000) live births. Reproductive fitness was 0.83. Direct and indirect estimates of the mutation rate were 4.4 (95% CI 0.9 to 7.9) x 10(-6)/gene/generation and 2.32 x 10(-6)/gene/generation respectively. There was no significant association between parental age or birth order and new mutations for VHL disease.

Adult↗
PubMed1990

Leukaemia and transient leukaemia in Down syndrome.

We have reviewed 215 published cases of leukaemia and transient leukaemia in Down syndrome. There is an over-representation of mosaic trisomy 21, possibly the result, at least in part, of a survival effect. The most intriguing observation is a bimodal distribution of maternal age, produced largely because cases with true leukaemia have a significantly higher maternal age than cases with transient leukaemia (33.5 versus 29.5 years). In conjunction with evidence that meiosis I nondisjunction is infrequent in transient leukaemia, this suggests different mechanisms for the etiology of leukaemia and transient leukaemia, and favours a locus predisposing to transient leukaemia proximal to the centromere on the long arm of chromosome 21.

Adolescent↗
PubMed1989

Mode of processing and hemisphere differences in the judgement of musical stimuli.

The relationship between processing strategy and ear asymmetry was examined in two experiments in which subjects were required to make judgements about monoaurally presented musical chords. In the first experiment, subjects without musical training showed a significant left ear advantage while in those with musical training a significant shift towards a right ear advantage was observed. Performance on the Embedded Figures Test (EFT) suggested a strong relationship between analytic processing style and right ear advantage which was significant in the musician groups. The effect of musical training status on ear asymmetry continued to be significant when the scores were adjusted for analytic processing. There was also a clear relationship between self-reported listening strategies and direction of ear asymmetry, with musicians generally reporting a much greater use of analytic strategies. The second experiment failed to demonstrate a significant influence of explicit instructions in how to carry out a chords task on the direction of ear advantages in musically untrained subjects. The results partially confirm earlier studies comparing subjects with and without musical training, and extend them by demonstrating a clear relationship between ear advantage and a separate measure of processing strategy. The findings of the second experiment, however, do not support clearly the hypothesis that differences in ear asymmetry are produced through the use of different processing strategies.

Adolescent↗
PubMed1987

Rebound hypertension after discontinuation of transdermal clonidine therapy.

Three (and possibly all four) elderly hypertensive patients who were followed sequentially after discontinuation of transdermal clonidine monotherapy manifested a rapid rise in blood pressure to levels above control (pre- and post-therapy) readings. No signs of an "overshoot" in plasma norepinephrine levels or symptoms of beta-adrenergic overactivity were seen. Such rebound hypertension suggests hypersensitivity to alpha-adrenergic receptor stimulation and could pose a heretofore unreported potential hazard to elderly or otherwise compromised patients who discontinue transdermal clonidine therapy.

Administration, Cutaneous↗
PubMed1986

Recovery of blood and bone marrow stem cells following intense chemotherapy and autologous bone marrow transplantation.

Sixteen patients with advanced (stage III) malignant melanoma were treated with escalating doses of intravenous BCNU and melphalan starting at 400 and 35 mg/m2, respectively, and escalating to 1,000 and 110 mg/m2, respectively, combined with autologous marrow transplantation. The duration of granulocytopenia and time to granulocyte recovery was similar in all groups regardless of chemotherapy dose. Platelet recovery was delayed in patients receiving the highest doses of chemotherapy. This study showed that bone marrow colony-forming units in culture took as long as 6 months to recover. This was adequate to bring peripheral blood counts to normal but not to pretreatment levels. These studies indicate that autologous bone marrow transplantation is beneficial in enhancing short-term recovery, but may not be beneficial in the long-term hematopoietic recovery.

Agranulocytosis↗
PubMed1985

Transdermal clonidine therapy in elderly mild hypertensives: effects on blood pressure, plasma norepinephrine and fasting plasma glucose.

Twenty patients aged 60-74 years entered a study on the effect of transdermal clonidine (Catapres-TTS) as monotherapy for mild hypertension [diastolic blood pressure (DBP) 90-104 mmHg]. Seventeen patients (85%) had a positive therapeutic response (DBP reduced to less than 90 mmHg or by greater than or equal to 5 mmHg). Patient acceptance was high and side effects mild; however, one-quarter of the patients experienced localized skin reactions. A slight increase in fasting plasma glucose level (mean delta = 20 mg/dl) was consistently observed. Transdermal clonidine led to a sustained decline in plasma catecholamine levels although this effect did not seem to be closely related to the observed decreases in blood pressure. Three out of four evaluable patients had a blood pressure 'overshoot' upon discontinuation of therapy to levels above pretreatment values. Transdermal clonidine appears to be effective and generally well tolerated in the treatment of mild hypertension in the elderly; however, more studies designed to investigate effects on glucose tolerance and the possible existence of a rebound syndrome are needed.

Administration, Topical↗
PubMed1976

Significance of genetic factors for the plasma insulin response to glucose in healthy subjects.

The intravenous glucose tolerance and plasma insulin response to glucose infusion were analysed in a twin and family material, comprising 279 healthy subjects. The relation between the blood glucose and plasma insulin values was studied by an analysis of the principal eigenvalues. The variables obtained were corrected for sex, age and weight, and standardized with regard to mean and variance. The results showed that at least four of the variables have appreciable familial correlations, corresponding to a heritability (h2) varying between 0.38 and 0.72. These correlations could not be accounted for by common environment alone. Thus, the beta cell function in normal man, as measured by a glucose challenge test, appears to be genetically regulated.

Adolescent↗