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Biomedical subjects

J M Jackson

Publications and source records attributed to J M Jackson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Melatonin shifts human circadian rhythms according to a phase-response curve.

A physiological dose of orally administered melatonin shifts circadian rhythms in humans according to a phase-response curve (PRC) that is nearly opposite in phase with the PRCs for light exposure: melatonin delays circadian rhythms when administered in the morning and advances them when administered in the afternoon or early evening. The human melatonin PRC provides critical information for using melatonin to treat circadian phase sleep and mood disorders, as well as maladaptation to shift work and transmeridional air travel. The human melatonin PRC also provides the strongest evidence to date for a function of endogenous melatonin and its suppression by light in augmenting entrainment of circadian rhythms by the light-dark cycle.

Adult↗
PubMed1992

Management of segmental defects by the Ilizarov intercalary bone transport method.

Seventeen patients with segmental skeletal defects were managed with the Ilizarov intercalary bone transport method, whereby an osseous defect is eliminated by elongating one fragment. On average, the regenerate new bone length measured 5.14 cm, corresponding to the creation of new osseous tissue equaling 13.7% of the bone's original length (range, 4.2%-35%). The average time in fixation was 9.6 months, including 4.8 months to transport the bone fragment throughout the limb. Numerous complications were encountered, most commonly wire-site sepsis and fixator instability. No serous nerve or vessel complications occurred. All but one patient eventually healed, although six patients required bone grafts, five at the target site and one at the level of the regenerate. Most of the difficulties encountered were due to a lack of technical knowledge with the method.

Adolescent↗
PubMed1991

Activation and inhibition of bovine carbonic anhydrase III by dianions.

We have found that many dianionic species, at millimolar concentrations, significantly activate or inhibit the bovine carbonic anhydrase III-catalyzed hydration of CO2. Dianionic species such as HPO2-4 and SO2-3, with pKb values near 7, are activators, whereas weakly basis species such as SO2-4 act as inhibitors. Both activation and inhibition are partial hyperbolic in nature and do not appear to compete with monoanionic linear inhibitors like N-3. Our kinetic data are consistent with a formal mechanism of action for carbonic anhydrase III that is directly analogous to that of carbonic anhydrase II, in which Lys-64 of carbonic anhydrase III can act as an intramolecular H+ transfer group during CO2 hydration. Our data suggest that dianionic inhibitors depress the rate of H+ transfer during turnover by stabilizing the protonated form of Lys-64. We postulate that dianionic activators enhance the rate of a rate-limiting H+ transfer step in the mechanism, probably by acting directly as H+ acceptors.

Animals↗
PubMed1991

ICI D7114 a novel selective beta-adrenoceptor agonist selectively stimulates brown fat and increases whole-body oxygen consumption.

1. ICI D7114 is a novel, beta-adrenoceptor agonist which stimulates whole body oxygen consumption in conscious rats, cats and dogs and brown adipose tissue (BAT) activity in conscious rats. Treatment of rats with ICI D7114 stimulated oxygen consumption (ED50, 0.04 mg kg-1, p.o.) and BAT mitochondrial guanosine diphosphate (GDP)-binding (ED50, 0.15 mg kg-1, p.o.) with no chronotropic effects on the heart at these doses. 2. Reference beta-adrenoceptor agonists, isoprenaline and clenbuterol, also stimulated oxygen consumption and BAT activity but were less selective because they also produced effects on heart rate at these doses. 3. Treatment of conscious rats with ICI D7114 did not attenuate the chronotropic effects on the heart of a subsequent isoprenaline challenge. 4. Administration of ICI D7114 or of its acid metabolite had no effect in a cat soleus muscle model of tremor or on blood potassium levels in the conscious dog, indicating lack of effects at beta 2-adrenoceptors. 5. The results indicate that ICI D7114 may have activity at atypical beta-adrenoceptors in brown adipose tissue leading to increased whole body oxygen consumption.

Adipose Tissue, Brown↗
PubMed1990

The effect of surgery and nutritional regimen on plasma lipoproteins and fat metabolites in man.

Plasma lipoproteins and fat metabolites were measured before and during the first five post-operative days in patients undergoing elective abdominal surgery of moderate severity. They received nutrition as total parenteral nutrition (TPN) or 4% dextrose saline (D S ) or isotonic aminoacids (IAA). Surgery caused an immediate fall in total and very low density lipoprotein triglyceride and total high density lipoprotein cholesterol but a rise in the high density lipoprotein subfraction 2 cholesterol. The increase in total triglyceride after 5 post-operative days was due principally to changes in triglyceride not carried by very low density lipoprotein and was related to the type of nutrition provided. There was no evidence of impaired intra-vascular lipolysis.

Journal Article↗
PubMed1990

Unilateral duplication of the cerebellar hemisphere and internal, middle, and external ear: a clinical case study.

This article presents the unique congenital anomaly complex of ipsilateral cerebellar hemisphere duplication and internal, middle, and external ear duplication. Diagnostic techniques included a head CT scan, a three-dimensional head CT scan, and a head MRI. An aberrant notochordal split was proposed as the embryologic mechanism leading to the development of such anomalies.

Abnormalities, Multiple↗
PubMed1990

The accuracy of predictions about progress of patients on a stroke unit.

The aim of the study was to check the accuracy of predictions about the factors which affect the progress, in physical abilities and activities of daily living, of patients admitted to a stroke unit. A series of 60 patients admitted consecutively to a stroke unit were assessed on tests of motor, functional and cognitive abilities at admission. On the basis of these assessments predictions were made about the abilities of the patients at discharge. Patients were assessed for level of motor abilities and activities of daily living at discharge and the accuracy of the predictions checked. Predictions were found to be significantly correlated with outcome but the relationships were not so close as to be useful for the clinical management of individual patients.

Activities of Daily Living↗
PubMed1988

The timing of menarche in juvenile rheumatoid arthritis.

A study of the age of menarche in juvenile rheumatoid arthritis (JRA) patients was undertaken to determine what factors affect the timing of menarche. There was a significant difference between the mean age of menarche for the 68 JRA patients and 46 controls (p = 0.015). No clear etiology for this difference was elucidated. Polyarticular-onset JRA patients had the oldest age of menarche, but this finding was of marginal statistical significance (p less than 0.05,pcorr less than 0.25). The multivariate model that included onset type, steroid use, and duration of disease weakly predicted age of menarche in the JRA group. This model suggests that, exclusive of height and weight parameters, duration of disease was the most important predictor of menarche in JRA.

Adrenal Cortex Hormones↗
PubMed1985

Sex ratio and sibship size in juvenile rheumatoid arthritis kindreds.

In a study of sibship size and sex ratio in juvenile rheumatoid arthritis, the anticipated sex ratios, including a marked female predominance in early onset pauciarticular disease and in polyarticular disease, were found. The size of the sibship showed a progressive increase with increasing age of the proband at onset of disease. In addition, the sex ratios of the sibs deviated from expected, among families where the proband's disease was characterized as either early onset pauciarticular or polyarticular in its presentation.

Adolescent↗
PubMed1985

External quality assurance in hematology. The programme of the Royal College of Pathologists of Australasia.

The Royal College of Pathologists of Australasia introduced a comprehensive national external quality assurance programme (QAP) in hematology in 1979. This now provides regular monthly trials of full blood counting, supplemented by 3-monthly sets of samples for a large variety of other tests for "state of the art" studies, together with case slides for diagnosis for 294 participants. In addition educational supplements are provided, based on one or other aspect of each major quarterly trial. The frequency and variety of tests and analysis of participants' results conform to suggested standards for similar national schemes elsewhere in the world. There is evidence that the programme has helped raise the standards of hematopathology in Australasia and has identified areas which require improvement. It is envisaged that the scheme will satisfy the requirements of state legislation designed to accredit pathology laboratories. Future development should include a refinement of objective methods of scoring performance, especially in areas such as morphology where participants' results cannot readily be expressed numerically.

Asia↗
PubMed1985

A reappraisal of pre-transfusion testing procedures in a hospital blood bank.

In recent years, experience with screening protocols for the detection of red cell antibodies has led to a reappraisal of pre-transfusion testing procedures. In the U.S.A. in particular, it has become accepted practice to perform only an antiglobulin crossmatch when an antibody screen has been negative. There is now debate in that country regarding the necessity of retaining even the antiglobulin crossmatch. In this laboratory, as is usual in Australia, room temperature, enzyme and antiglobulin tests are used for both antibody screening and crossmatching. A review was therefore conducted of the results of screening 58,227 samples from approximately 40,000 patients, involving 126,771 crossmatched blood units over a 53 mth period. Eight hundred and seventy-two red cell antibodies were detected in 718 patients. Forty-four of these antibodies were detected only in the crossmatch, and of these 23 were of potential clinical significance. Fourteen of the 23 were detected by the antiglobulin test, 8 by an enzyme test and only 1 by the saline method. Of 107 antibodies detected only in the room temperature phase, none were of clinical significance. The results indicate that exclusion of room temperature tests from all pre-transfusion testing, and deletion of enzyme tests from the crossmatch will not compromise patient safety.

Blood Grouping and Crossmatching↗
PubMed1985

Complementation with HLA-A and HLA-D locus alleles in ankylosing spondylitis with peripheral arthritis.

Fifty-nine patients with HLA-B27 positive ankylosing spondylitis were HLA genotyped to look for immunogenetic differences between patients with associated peripheral arthritis and those with disease limited to the axial skeleton. An association was found between the peripheral arthropathy and 2 antigens, HLA-A11 and HLA-DR7 at the p less than 0.05 level. Complementation between these 2 alleles and HLA-B27 occurred in both the cis and trans positions. Four patients with peripheral arthritis had a rare HLA-B27 haplotype (HLA-B27, HLA-DR7) which was not found in the group with axial disease alone.

Adolescent↗
PubMed1984

Naftidrofuryl and the nitrogen, carbohydrate, and lipid responses to moderate surgery.

The effect of twice daily infusions of 200 mg naftidrofuryl on the six day cumulative losses of urinary nitrogen after moderate surgery was studied in 32 patients maintained on an intravenous infusion of 4% dextrose and saline. A previous report of the ability of naftidrofuryl to reduce loss of nitrogen was not substantiated, although changes in metabolism in the immediate postoperative period suggested that the drug might exert some advantageous metabolic effect. Further investigations with other nutritional regimens are warranted.

Adult↗