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Biomedical subjects

G Mackenzie

Publications and source records attributed to G Mackenzie.

At least 37 records · Page 2Linked to original sources

Prognostic indices in stroke.

Two hundred and six patients with acute stroke admitted consecutively to District General Hospitals, were studied for a period of six months. Significance tests conducted singly detected 21 factors present during the first 48 h of stroke, which were related to outcome six months later in terms of both mortality and functional recovery. Among these significant factors were various measures of perceptual dysfunction, including Albert's Test. Multivariate statistical analysis which included discriminant analysis and linear logistic modelling, revealed six factors (Albert's Test Score, leg function, level of consciousness, arm power, weighted mental score and ECG changes) which were significantly and independently related to outcome. A statistical model based on these factors predicted functional outcome with an overall accuracy of 67 per cent and mortality with an accuracy of 83 per cent. This model provides a useful basis for stratification in future randomized controlled trial in stroke, and may have a role in the management of the individual stroke patient.

Acute Disease↗

Does a booklet on breast self-examination improve subsequent detection rates?

Of 28 788 women aged 40 to 74 registered at 28 university teaching practices in greater Belfast, half were randomly selected to receive a booklet on breast self-examination from their general practitioner at the start of the study and 1 year later. The frequency of breast abnormalities was identical in both groups (0.83%) during the 2-year follow-up. Early malignant breast cancers (stages TX, TO, Tla) were significantly more frequent in the intervention group (53.6%) than in the control group (24.3%). Among women in the intervention group with malignant lesions, 2 sites, left nipple and left inner/upper quadrant, were significantly less frequently involved. These findings in relation to staging and site were confirmed by multivariate comparisons. The intervention group also had a smaller average tumour size (24.0 mm compared with 32.6 mm) due to significantly smaller benign tumours and the absence of the relationship between delay and tumour size evident in the control group.

Adult↗

Comparison of infrared coagulation and rubber band ligation for first and second degree haemorrhoids: a randomised prospective clinical trial.

One hundred and thirty seven previously untreated out-patients with first and second degree haemorrhoids were allocated at random to treatment by infrared coagulation (n=66) or rubber band ligation (n=71). Complete follow up was obtained in 122 patients (60 who had undergone infrared coagulation (group 1), and 62 rubber band ligation (group 2)) at periods from three months to one year after completion of treatment. Infrared coagulation produced a satisfactory outcome in 51 patients (85%): 34 were rendered asymptomatic and 17 improved. Rubber band ligation produced a satisfactory outcome in 57 patients (92%): 33 were rendered asymptomatic and 24 improved. Both methods were equally effective in first and second degree haemorrhoids. The incidence of side effects, particularly discomfort, during and after treatment was significantly higher in those treated by rubber band ligation (p less than 0.001). This appeared to be an appreciable deterrent to future patient compliance. The number of patients losing more than 24 hours from work was higher after rubber band ligation than after infrared coagulation. The number of treatments necessary to cure symptoms did not differ significantly between the two methods. Infrared coagulation was significantly faster than rubber band ligation (p less than 0.001). Infrared coagulation is a simple, fast, and effective outpatient method for the treatment of first and second degree haemorrhoids with fewer troublesome side effects and higher patient acceptability than rubber band ligation.

Adult↗

Isolation of nonsense mutants of lipid-containing bacteriophage PRD1.

We isolated nonsense mutants of bacteriophage PRD1, a lipid-containing polyhedral virus capable of infecting many genera of gram-negative bacteria. These mutants were grouped into 19 classes on the basis of genetic complementation and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis. PRD1 infection led to the synthesis of at least 25 viral proteins, 17 of which were components of mature virions. The synthesis of proteins fell into the following three classes: very early, middle early, and late. Two of the very early proteins, P1 and P8, had an effect on DNA synthesis, host protein synthesis shutoff, and the turning on of middle and late protein synthesis. Another very early protein, P12, was involved in the shutoff of early protein synthesis. Two genes were identified as affecting lysis of the host. One appeared to be a lysin, whereas the other was an accessory lytic factor.

Genetic Complementation Test↗

Assembly of bacteriophage PRD1: particle formation with wild-type and mutant viruses.

Bacteriophage PRD1 contains DNA, 17 proteins, and lipid. The assembly pathway involves the formation of empty particles that contain lipid and all of the proteins of mature virions, with the possible exception of one. The major and minor capsid proteins, P3 and P5, occur as soluble multimers before they appear in the empty particles. Nonsense mutants of PRD1 that involve structural proteins of the virion other than P3 form particles that are missing only the defective protein. Those mutants that are unable to form P3 do not form particles. Mutations in two other genes that code for nonstructural proteins (P10, which is membrane bound, and P17, which is soluble) result in the absence of particles. Protein P2 is necessary for adsorption to host cells. Protein P9 is necessary for particle filling with DNA, whereas P20 and P22 are necessary for stable DNA packaging. Electron micrographs of infected cells confirmed the gradient analysis of particle formation. No free vesicles were observed in mutants that could not form complete empty particles, indicating that there are no free intermediate particles before the empty virions.

Bacteriophages↗

The prevalence of problem drinking in Northern Ireland: a population study.

A total of 3 755 individuals constituting 85.5% of a stratified random sample of all Northern Ireland electors were interviewed about their drinking patterns as the major element in a community health study. It was found that, according to pre-determined criteria, 11.2 per 1 000 were alcoholics and another 28.5 per 1 000 were substantially preoccupied with alcohol, giving an estimated provincial total of 40 000 (+/- 3 300) abnormal drinkers. Using appropriate multivariate statistical methods the prevalence of problem drinking was found to depend (in rank order of importance) on sex, age, religious denomination and area of residence.

Adolescent↗

Sporopollenin. A novel, naturally occurring support for solid phase peptide synthesis.

Sporopollenin from Lycopodium clavatum has been found to be capable of acting as a solid support for peptide synthesis. It is stable to chloromethylation and to the standard deblocking procedures and its constant mesh size, ready commercial availability, and constant molecular structure give it potential important practical advantages over synthetic resins.

Biopolymers↗

Some metabolic effects of maximal exercise in the horse and adaptations with training.

The effects of intermittent maximal exercise (galloping) before and after a 10 week training programme were studied in 6 horses. Determinations were carried out on venous blood for packed cell volume, total plasma protein, glucose, glycerol, free fatty acids, lactate, 11-hydroxycorticosteroids, blood gases and pH. There were marked changes associated with galloping and some of these could be modified with training. The major findings included (i) an elevated blood glucose, (ii) a large increase in glycerol, which was greatest at 30 min post-exercise and was higher following training, (iii) smaller increases in free fatty acids following training, (iv) higher levels of lactate after training, (v) a marked fall in pH which was less after training, (vi) an increase in 11-hydroxycorticosteroids with possibly a more rapid return to resting levels following training. It was concluded that with maximal exercise in the horse both glycogen and free fatty acids served as important substrates for working muscle, and following training greater utilisation of both these substrates occurred.

Animals↗

Effect of training on some metabolic changes associated with submaximal endurance exercise in the horse.

The effects of prolonged cantering before and after a 10 week training programme were studied in 6 horses. Determinations were carried on on venous blood for packed cell volume, glucose, glycerol, free fatty acids, beta-hydroxybutyrate, 11-hydroxycorticosteroids, pH and pCO2. Exercise caused a slight increase in glucose, lactate and pH, a moderate rise in PCV, glycerol and free fatty acids, and a marked rise in 11-hydroxycorticosteroids. A decrease in venous pCO2 occurred and a slight but not significant decrease in beta-hydroxybutyrate. Training was found to cause no significant difference in the changes seen. However, there was a tendency for exercise to result in higher 11-hydroxycorticosteroid levels after training.

11-Hydroxycorticosteroids↗