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Biomedical subjects

A Evans

Publications and source records attributed to A Evans.

At least 325 records · Page 18Linked to original sources
PubMed1992

An import-competent precursor of small subunit of ribulose-1,5-bisphosphate carboxylase generated by factor Xa cleavage from a beta-galactosidase fusion expressed in Escherichia coli.

A plasmid-encoding fusion protein interlinked by factor Xa recognition sequence between beta-galactosidase and a precursor of the small subunit of wheat ribulose-1,5-bisphosphate carboxylase has been constructed. The plasmid directed abundant synthesis of the fusion protein in Escherichia coli. The recombinant protein was accumulated in an aggregated form that was associated with the bacterial membranes. A procedure was developed to isolate the fusion protein in a relatively pure and soluble form. Bovine factor Xa cleaved the isolated chimera to generate the complete chloroplast precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase from the fused beta-galactosidase. The cleaved precursor protein was imported into the isolated chloroplasts and processed to yield its mature counterpart.

Amino Acid Sequence↗
PubMed1992

Anatomic basis of amygdaloid and hippocampal volume measurement by magnetic resonance imaging.

Both the amygdala and the hippocampus are involved in the pathogenesis of a number of neurologic conditions, including temporal lobe epilepsy, postanoxic amnesia, and Alzheimer's disease. To enhance the investigation and management of patients with these disorders, we developed a protocol to measure the volumes of the amygdala and as much of the hippocampus as possible (approximately 90 to 95%) using high-resolution MRI. We present the anatomic basis of these two protocols and our results in normal control subjects. These volumetric studies of the amygdala may clarify the role of this structure in the pathogenesis of temporal lobe epilepsy.

Adult↗
PubMed1992

The successful development of decentralised health service management: an evaluation of area health services in New South Wales.

Decentralised provision and management of health services has been regarded by many governments as a means of improving the management of hospitals and health services that have become increasingly expensive, complex and fragmented. There has been no known formal evaluation in Australia of the success or otherwise of health services where such decentralised structures have been put in place. Known as 'area health services', decentralised administration of public hospital and health services were first introduced in Sydney, Australia in 1974. The experience has been evaluated. The outcome appears to be successful in terms of rationalisation, co-ordination and equity, but also because the decentralised health authority embraces responsibility for the health of all members of their community and is not confined to patients who attend hospitals and clinics.

Catchment Area, Health↗
PubMed1992

Color-vision deficiency--what does it mean?

Color-vision deficiency is a disorder affecting a significant proportion of the population, yet it remains poorly understood by school personnel as well as the general public. This article examines the many ways abnormal color perception affects peoples' lives. The role of the school nurse in detection of the problem, plus education and counseling of the affected student, parents, and teachers is discussed.

Adult↗
PubMed1991

Epstein-Barr virus antibody patterns preceding the diagnosis of non-Hodgkin's lymphoma.

Immunosuppressed patients who develop non-Hodgkin's lymphoma (NHL) have abnormal antibody responses against the Epstein-Barr virus (EBV) prior to the diagnosis of malignancy. To see if this is also true of "spontaneous" cases in the general population, we undertook a collaborative serologic case-control study. From 4 serum banks containing specimens from over 240,000 persons, 104 subjects were identified for whom a blood specimen had been stored an average of 63 months before diagnosis of NHL, and 259 controls matched for age, sex, ethnic group and date of serum collection. The relative risks (RR) for subsequent development of NHL associated with elevated levels of IgG and IgM antibodies against viral capsid antigen were 2.5 (95% confidence interval = 1.1-5.7) and 3.2 (1.3-7.5), respectively; these associations increased with age at diagnosis. For the nuclear antigen, the distribution of titers for cases was more restricted than that of controls, with fewer cases having either elevated or low titers, RR = 0.5 (0.2-1.4) and 0.5 (0.2-1.2), respectively. Cases had significantly lower antibody titers against the cytomegalovirus, RR = 0.4 (0.2-0.9). These findings suggest that, at least for some patients, NHL is preceded by an enhanced level of endogenous immunosuppression with resultant EBV activation. This observation supports the role of EBV either directly in the development of NHL or as a primary marker of immune dysfunction.

Adult↗
PubMed1991

Admission to child health surveillance lists: the views of FHSA general managers and general practitioners.

OBJECTIVES: To find out the sources of advice that were helpful to managers of family health services authorities in drawing up the criteria for admission of general practitioners to the child health surveillance lists; to determine the criteria used for admission of general practitioners to the family health services authorities' child health surveillance lists; to find out the changes general practitioners have made in child health surveillance in their practices; to determine the experiences of general practitioners relating to admission to the child health surveillance lists and to training in child health surveillance. DESIGN: Survey by postal questionnaire. SUBJECTS: General managers of all family health services authorities in England and Wales; all general practitioners in Yorkshire and Humberside. RESULTS: Managers of 80 of 93 family health services authorities replied (86%). A total of 62 (78%) found local community paediatricians helpful in compiling criteria for admission to child health surveillance lists, and 46 (57%) found national guidelines helpful. Fifty seven (71%) accepted general practitioners who had completed an approved course, and 45 (56%) accepted those with three or more years' experience of child health surveillance. Of the 1966 questionnaires sent to general practitioners, 1233 were satisfactorily completed (63%). Of the 919 respondents who had applied to be put on child health surveillance lists, 673 (73%) had been permanently accepted; of these, 441 (65%) had done an approved course and 375 (56%) had had three or more years' experience of child health surveillance. Of the 145 (16%) not accepted, 57 (39%) had done an approved course and 71 (49%) had three or more years' experience. Respondents reported variable quality and availability of courses in child health. CONCLUSIONS: Acceptance of general practitioners on to child surveillance lists has not been carried out consistently despite national guidelines setting out criteria for acceptance.

Child Health Services↗
PubMed1991

Dopa decarboxylase activity of the living human brain.

Monoaminergic neurons use dopa decarboxylase (DDC; aromatic-L-amino-acid carboxy-lyase, EC 4.1.1.28) to form dopamine from L-3,4-dihydroxyphenylalanine (L-dopa). We measured regional dopa decarboxylase activity in brains of six healthy volunteers with 6-[18F]fluoro-L-dopa and positron emission tomography. We calculated the enzyme activity, relative to its Km, with a kinetic model that yielded the relative rate of conversion of 6-[18F]fluoro-L-dopa to [18F]fluorodopamine. Regional values of relative dopa decarboxylase activity ranged from nil in occipital cortex to 1.9 h-1 in caudate nucleus and putamen, in agreement with values obtained in vitro.

Brain↗
PubMed1991

Epstein-Barr virus antibody patterns preceding the diagnosis of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) patients have elevated IgG and IgA antibody titers against the Epstein-Barr viral capsid antigen (VCA) and the diffuse component of the early antigen complex (EA-D) at diagnosis. Several studies have implied that the presence of anti-VCA-IgA can be used as a screening marker for early NPC. To evaluate this further, we undertook a serologic case-control study based on four serum banks which together had specimens from over 240,000 persons. Seven cases of undifferentiated or poorly differentiated NPC were diagnosed in the period after serum collection ranging from 26 months to 154 months. Two controls per case matched on serum bank, age, sex, race, and date of serum collection were selected by a predetermined random process. For anti-VCA-IgG, the geometric mean titer for cases (88.3) was significantly higher than that for controls (75.5, P less than 0.05). The difference was greatest among the Asian patients. No significant differences were found for anti-VCA-IgA, anti-EA-D, and anti-EA-R or anti-EBNA. No time effects were evident when titers were plotted against time of blood collection preceding diagnosis. Our results do not suggest EBV activation in the period preceding NPC diagnosis, nor that detectable IgA antibody against VCA is a marker for early disease.

Adult↗
PubMed1991

The diphosphonate space: a useful quantitative index of disease activity in patients undergoing hydroxy methylene diphosphonate (HMDP) bone imaging for Paget's disease [corrected].

Comparison between the plasma levels of intravenously injected technetium 99m hydroxy methylene [corrected] diphosphonate (99mTc-HMDP) and chromium 51 ethylene diamine tetra-acetic acid (51Cr-EDTA) reflects the uptake of diphosphonate into bone (the diphosphonate space). This can be used as an index of skeletal function in metabolic bone disease. In a series of 49 patients with Paget's disease the diphosphonate space (DPS) correlated well with other indicators of disease activity such as alkaline phosphatase and urinary hydroxyproline levels. The DPS is a good predictor of the volume of skeletal involvement as estimated from bone images. The DPS also provides a sensitive indicator of response to treatment with intravenously administered bisphosphonate. The DPS is simple to perform and is a useful adjunct to routine bone imaging.

Alkaline Phosphatase↗
PubMed1991

An analysis of the accuracy of prediction of intraocular implant power in the myopic patient.

A series of 90 eyes of 88 myopic patients who underwent extracapsular cataract surgery with intraocular lens implants (IOLs) between 1984 and 1989 were analysed in a retrospective study. The axial length as obtained by ultrasonic A scan and keratometry readings were applied to the SRK1 and modified SRK (SRK2) formulae and the result compared with the actual post-operative state achieved.

Cataract Extraction↗
PubMed1990

Endothelial cell expression of the intercellular adhesion molecule-1 (ICAM-1) in the central nervous system of guinea pigs during acute and chronic relapsing experimental allergic encephalomyelitis.

This study investigated the expression of intercellular adhesion molecule-1 (ICAM-1; CD54) by cells of the central nervous system (CNS) during acute experimental allergic encephalomyelitis (EAE) and chronic relapsing EAE (CREAE). In the CNS of normal guinea pigs, only a few endothelial cells expressed detectable levels of ICAM-1, whereas during the active phases of the disease ICAM-1 was present on cells of the perivascular infiltrate and the endothelia of both lesion- and non-lesion-associated blood vessels. In addition, cultured cerebrovascular endothelia maintained in 'standard' culture medium did not express ICAM-1, but they could be induced to express this antigen on incubation in a lymphocyte-conditioned medium. These findings suggest that the induction of ICAM-1 on CNS endothelia may be important in antigen presentation or in promoting lymphocyte extravasation across the blood-brain barrier in inflammatory disorders of the CNS.

Animals↗
PubMed1990

Peer interaction in infant chimpanzees.

The peer interactions of 6 infant chimpanzees (Pan troglodytes) ranging in age from 18 to 50 months were observed in a seminatural context. The infants and their mothers lived as members of a captive social group at the Yerkes Regional Primate Research Center. An analysis of contact initiations between infants indicated that the most preferred peer interactant was the youngest and the least preferred was the oldest infant. Infants also initiated more interactions with the offspring of adults that had the closest relationships with both themselves and their mothers. These results indicate that a number of factors may influence the peer affiliations of infant chimpanzees, including the age of the infant and the mother's social relationships.

Age Factors↗
PubMed1990

Sodium, potassium, body mass, alcohol and blood pressure in three United Kingdom centres (the INTERSALT study).

Standardised data on blood pressure, 24 h urinary electrolyte excretion, body mass index (BMI) and alcohol intake were collected as part of the INTERSALT study in 598 men and women aged 20-59 years, selected randomly from three population groups in the United Kingdom. For the three centres combined, mean systolic blood pressure was 121.4 mm Hg and diastolic pressure 72.1 mm Hg, urinary sodium excretion 152.1 mmol/24 h, urinary potassium excretion 61.0 mmol/24 h, urinary sodium/potassium ratio 2.64 and BMI 25.2 kg/m2. Prevalence of heavy alcohol drinking in men (greater than or equal to 300 ml/week) was 27.5 per cent. Applying overall INTERSALT regression coefficients to the United Kingdom data suggested that modest changes in average sodium and potassium intakes, together with reductions in the prevalence of obesity and (in men) of heavy alcohol drinking could lead to important reductions in average population blood pressures and the prevalence of hypertension. The potential of this multifactorial approach to blood pressure control was illustrated by stratifying individuals within each of the United Kingdom centres by sodium and potassium excretion, BMI and alcohol intake. The 20 (out of 299) men considered at 'lower risk' for high blood pressure with respect to the above variables had systolic pressure lower by 11 mm Hg (P less than 0.01); for the 27 (out of 299) 'lower risk' women, systolic pressure was lower by 5 mm Hg (P = 0.06). These non-pharmacological approaches towards more favourable blood pressure levels could be accompanied by reductions in mortality from stroke and coronary heart disease.

Adult↗