PubMed Health⌕ Search

Biomedical subjects

J M Jackson

Publications and source records attributed to J M Jackson.

At least 19 recordsLinked to original sources
PubMed1995

Plasma non-esterified fatty acid response to dialysate acetate concentration during haemodialysis in humans.

We have inhibited the in vitro generation of non-esterified fatty acids in plasma samples taken during haemodialysis by cooling the samples rapidly, centrifuging and freezing within 5 min of sampling and completing the assay on the same day. The relationship of non-esterified fatty acid concentrations during haemodialysis to the acetate concentration of the dialysate and the profile of circulating lipase activities was studied. With this sample-handling protocol we found lower non-esterified fatty acid concentrations than reported in many other studies and the results suggest that, under normal conditions of haemodialysis, the circulating non-esterified fatty acid concentrations and the associated risk of unwanted side-effects may have been previously over-estimated due to artefactual in vitro sample lipolysis. We also showed that, at the end of dialysis, when circulating lipase activities were least, the non-esterified fatty acid concentrations were lower (P < 0.05) with an acetate dialysate containing 37 mmol/l acetate than with a bicarbonate dialysate containing 3 mmol/l acetate.

Acetates↗
PubMed1995

Distance and pairing effects on the brownDominant heterochromatic element in Drosophila.

We examined the behavior of the brownDominant (bwD) heterochromatic insertion moved to different locations relative to centric heterochromatin. Effects were measured as the degree of silencing of a wild-type brown eye pigment gene by bwD across a tandem duplication. A series of X-ray-induced effects were recovered at high frequency. Cis-acting enhancers were obtained by relocation of the duplication closer to autosomal heterochromatin. Enhancers were also recovered on the homologous chromosome when it was similarly rearranged, revealing a novel interhomologue effect whereby interactions occur between genetic elements near opposite ends of a chromosome arm rather than between paired alleles. Cis-acting suppressors were obtained as secondary rearrangements in which the duplication was moved farther away from heterochromatin. Suppression was correlated with loss of cytological association between bwD and the polytene chromocenter. Surprisingly, the distance from bwD to the chromocenter was not correlated with the strength of enhancement or suppression. We propose that bwD fails to coalesce with the chromocenter when its position along the chromosome places it beyond a threshold distance from heterochromatin, and this threshold depends upon the configuration of both the chromosome carrying bwD and its paired homologue.

Alleles↗
PubMed1994

Immunophenotyping of childhood acute lymphoblastic leukemia in Saudi Arabia: second look.

Geographical variations in the incidence of disease are of considerable theoretical and practical importance. It has been claimed that the distribution of acute lymphoblastic leukemia (ALL) phenotypes in Saudi Arabia is different from that recorded in the Western literature. One hundred and twelve (112) patients under 15 years of age, diagnosed as ALL between January 1992 and May 1994 had immunophenotypes performed on their blast cells. Common ALL (cALL) together with pre-B-ALL, formed 86.5% of the total; B-cell 3%, T-cell 6% and null cell 4.5%. These figures are not significantly different from the Western literature. A previous claim from this institution in 1990, that both null and B-cell ALL were significantly increased compared with elsewhere, is not supported by the present figures. Age and sex distribution, and FAB classification, L1 77%, L2 20% and L3 3%, were also of the same order as described elsewhere and, in particular, there was no increase in the frequency of L3 subtype.

Adolescent↗
PubMed1993

CEO address.

Explore the source record for details and available documents.

Costs and Cost Analysis↗
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

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↗