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Biomedical subjects

K E Halnan

Publications and source records attributed to K E Halnan.

At least 19 recordsLinked to original sources
PubMed1992

The Hong Kong Academy of Medicine.

The Hong Kong Academy of Medicine is being founded this year. This brief article gives something of the background, structure and function of the Academy.

Academies and Institutes↗
PubMed1985

Radio-iodine treatment of hyperthyroidism--a more liberal policy?

The main and most valid evidence we have is that on direct follow-up of treated patients. This has been well done in thousands of patients in two countries with very good medical care and over long periods--10 to 15 years or more. On the other hand there is no doubt about radiation carcinogenesis, and thyroid cancer has been caused in children by low-dose x-ray therapy. The possibility of other cancer and of leukaemogenesis is also real. The evidence for this is reviewed and risk estimates given. Experimental work and radiation biology is reviewed and it is suggested that the risk of thyroid cancer from the usual radio-iodine doses given for treatment is low because of cell killing or sterilization, and animal evidence is discussed that supports this. The final position appears to be that no risk has yet been demonstrated in man and evidence in general suggests that if there is indeed a cancer risk it will be less than about 0.1%. It is suggested that this is not dissimilar to surgical risks, except that these are more immediate as compared with the long latent period for development of radiation-induced cancer. Genetic risks are also discussed and again have not been demonstrated in man from this treatment and should in any case be low. The risk to children is also considered; there is no direct evidence of risk but only small numbers have been treated--nevertheless the hypothetical risk may be counterbalanced by the benefits. Administration of radio-iodine therapy to pregnant or lactating women must be scrupulously avoided; both cause significant risks. Finally, if a more liberal policy be accepted it is worth while giving optimum treatment, and evidence is given suggesting low-dose treatment similar in effect to surgical thyroidectomy and followed temporarily if need be by anti-thyroid drug treatment.

Abnormalities, Radiation-Induced↗
PubMed1985

Blood flow and oxygen utilisation in the contralateral cerebral cortex of patients with untreated intracranial tumours as studied by positron emission tomography, with observations on the effect of decompressive surgery.

Using positron emission tomography, regional cerebral blood flow and oxygen utilisation were measured in the contralateral cortex of 14 patients with a variety of intracranial tumours. A comparison was made with cortical values derived from 14 normal controls. Compared with normal subjects, patients with brain tumours had a significant reduction in oxygen utilisation and blood flow in their contralateral cortex. Decompression resulting from craniotomy and biopsy, led to a partial reversal of this cerebral hypofunction.

Adult↗
PubMed1984

Positron emission tomography for in-vivo measurement of regional blood flow, oxygen utilisation, and blood volume in patients with breast carcinoma.

Regional blood flow, oxygen extraction ratio, and oxygen utilisation were measured in nine patients with breast carcinoma by means of the oxygen-15 steady-state inhalation technique and positron emission tomography. Regional blood volume was measured by means of tracer amounts of carbon-11-labelled carbon monoxide. The regional blood flow was consistently higher in non-necrotic tumour tissue than in surrounding normal breast tissue or contralateral normal breast. Oxygen utilisation was slightly higher in the tumour. The regional oxygen extraction ratio (ie, the fraction of oxygen extracted from the nutritional blood supply) was appreciably lower in the tumour than in normal breast tissue. These findings suggest that there is, at least on a macroscopic level, no supply-limited impairment of respiration in human breast cancer.

Aged↗