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Biomedical subjects

M James

Publications and source records attributed to M James.

At least 19 recordsLinked to original sources
PubMed1992

L-dopa withdrawal in Parkinson's disease selectively impairs cognitive performance in tests sensitive to frontal lobe dysfunction.

A group of ten patients with idiopathic Parkinson's disease (PD) was tested on a series of automated tests of learning, memory, planning and attention whilst either on or off L-dopa medication. Controlled withdrawal of L-dopa interfered with aspects of performance on three of the tests that had previously been shown to be sensitive to frontal lobe dysfunction; a spatial working memory task, the Tower of London planning test, and a visual discrimination paradigm that also included intra- and extra-dimensional shift tests of selective attention. More specifically, errors were increased in the spatial working memory test, and both the accuracy and latency of thinking were impaired. Thinking time was significantly slowed following L-dopa withdrawal, even though the possible contaminating effects on motor slowing were fully controlled by a yoked control procedure. Nine out of ten patients reached a further stage of the visual discrimination, set-shifting paradigm when on, rather than off, L-dopa medication. Spatial span was also impaired off medication, but there were no effects of L-dopa withdrawal on tests of pattern and spatial recognition memory, simultaneous and delayed matching to sample or visuospatial conditional associative learning. Comparisons with a large control group confirmed previous findings that PD is associated with deficits on the majority of these tests. The results are discussed in terms of the fronto-striatal, dopamine dependent nature of some of the cognitive deficits found in PD, but the apparent dopamine-independent nature of deficits in other aspects of cognitive functioning, notably in tests of visual recognition memory and associative learning.

Brain Diseases↗
PubMed1992

Amniotic fluid and umbilical artery levels of sex hormones and prostaglandins in human cocaine users.

Biochemical evaluation of amniotic fluid contents is often used to monitor fetal secretory and excretory functions. To determine whether cocaine use during pregnancy affects fetal endocrine secretions, amniotic fluid and umbilical artery samples were collected at term, and selected gonadal hormones and prostaglandins were assayed. Gestational age, birth weights, and placental weights were recorded. The data showed that birth weights were significantly decreased (P less than 0.001) in cocaine users, but gestational age and placental weights were unaffected. Amniotic fluid levels of androstenedione and testosterone were decreased (P less than 0.05) in males born to cocaine users; females were not affected. Prostaglandins (PGF2 alpha and PGE2) were significantly increased (P less than 0.01) in cocaine users. In the umbilical artery, follicle-stimulating hormone was increased (P less than 0.01) in males and females, while luteinizing hormone was increased (P less than 0.01) only in males. We conclude that cocaine passes through the placenta and affects the fetal testes-hypophyseal endocrine system.

Adult↗
PubMed1992

Endothelial cell seeding of damaged native vascular surfaces: prostacyclin production.

Endothelial cell seeding has been successful in reducing the thrombogenicity of prosthetic vascular grafts in animal and clinical studies. The reduction in thrombogenicity may be attributed to the intrinsic properties of endothelial cells themselves, and their ability to produce anti-thrombogenic mediators such as prostacyclin, and endothelium-derived relaxing factor. Endothelial seeding of damaged vascular surfaces produced during percutaneous transluminal angioplasty and endarterectomy is an attractive possibility due to the excellent attachment characteristics of the sub-endothelial tissue exposed during these procedures. The ability of endothelial seeded damaged vascular surfaces to produce prostacyclin was measured in an in vitro model of vascular injury. Endothelial-seeded damaged surfaces produced significantly higher prostacyclin release than did vessels damaged by balloon dilatation (265.5 pg cm-2 min-1 and 87.5 pg cm-2 min-1 respectively). This study provides evidence that endothelial seeding of damaged native vascular surfaces is technically feasible and that seeding may reduce the thrombogenicity of vascular surfaces following balloon dilatation.

Angioplasty, Balloon↗
PubMed1992

Cognitive performance in multiple system atrophy.

The cognitive performance of a group of patients with multiple system atrophy (MSA) of striato-nigral predominance was compared with that of age and IQ matched control subjects, using three tests sensitive to frontal lobe dysfunction and a battery sensitive to memory and learning deficits in Parkinson's disease and dementia of the Alzheimer type. The MSA group showed significant deficits in all three of the tests previously shown to be sensitive to frontal lobe dysfunction. Thus, a significant proportion of patients from the MSA group failed an attentional set-shifting test, specifically at the stage when an extra-dimensional shift was required. They were also impaired in a subject-ordered test of spatial working memory. The MSA group showed deficits mostly confined to measures of speed of thinking, rather than accuracy, on the Tower of London task. These deficits were seen in the absence of consistent impairments in language or visual perception. Moreover, the MSA group showed no significant deficits in tests of spatial and pattern recognition previously shown to be sensitive to patients early in the course of probable Alzheimer's disease and only a few patients exhibited impairment on the Warrington Recognition Memory Test. There were impairments on other tests of visual memory and learning relative to matched controls, but these could not easily be related to fundamental deficits of memory or learning. Thus, on a matching-to-sample task the patients were impaired at simultaneous but not delayed matching to sample, whereas difficulties in a pattern-location learning task were more evident at its initial, easier stages. The MSA group showed no consistent evidence of intellectual deterioration as assessed from their performance on subtests of the Wechsler Adult Intelligence Scale (WAIS) and the National Adult Reading Test (NART). Consideration of individual cases showed that there was some heterogeneity in the pattern of deficits in the MSA group, with one patient showing no impairment, even in the face of considerable physical disability. The results show a distinctive pattern of cognitive deficits, unlike those previously seen using the same tests in patients with Parkinson's and Alzheimer's diseases, and suggesting a prominent frontal-lobe-like component. The implications for concepts of 'subcortical' dementia and 'fronto-striatal' cognitive dysfunction are considered.

Adult↗
PubMed1992

Fronto-striatal cognitive deficits at different stages of Parkinson's disease.

Groups of patients with idiopathic Parkinson's disease, either medicated or unmedicated, were compared with matched groups of normal controls on a computerized battery previously shown to be sensitive to frontal lobe dysfunction, including tests of planning, spatial working memory and attentional set-shifting. In a series of problems based on the 'Tower of London' test, medicated patients with Parkinson's disease were shown to be impaired in the amount of time spent thinking about (planning) the solution to each problem. Additionally, an impairment in terms of the accuracy of the solution produced on this test was only evident in those patients with more severe clinical symptoms and was accompanied by deficits in an associated test of spatial short-term memory. Medicated patients with both mild and severe clinical symptoms were also impaired on a related test of spatial working memory. In contrast, a group of patients who were unmedicated and 'early in the course' of the disease were unimpaired in all three of these tests. However, all three Parkinson's disease groups were impaired in the test of attentional set-shifting ability, although unimpaired in a test of pattern recognition which is insensitive to frontal lobe damage. These data are compared with those previously published from a group of young neurosurgical patients with localized excisions of the frontal lobes and are discussed in terms of the specific nature of the cognitive deficit at different stages of Parkinson's disease.

Aged↗
PubMed1992

A novel G protein-coupled receptor kinase gene cloned from 4p16.3.

Within the Huntington's disease (HD) candidate region of 4p16.3, the D4S127 locus displays strong linkage disequilibrium with the defect and anchors a conserved haplotype found on many HD chromosomes. To isolate genes from this region we have applied the exon amplification technique to overlapping cosmids spanning D4S127. Here, we report the discovery of a new gene encoding a novel member of a family of protein kinases that specifically phosphorylate the activated forms of G protein-coupled receptors. Such kinases are thought to participate in desensitization of specific receptors, thereby blocking further signal transduction. This gene must now be carefully scrutinized to determine whether it might be involved in HD.

Amino Acid Sequence↗
PubMed1992

Potential use of tissue adhesive in urinary tract surgery.

The search for a tissue adhesive which obviates the need for suture materials in the apposition of wound edges is not new. The early adhesive products lacked the required safety and efficacy. Experimental use of a new fibrin adhesive has shown that it may have potential use where inflammatory reaction to the suture material is undesirable or water-tight sealing of the anastomosis is required.

Animals↗
PubMed1991

Multiparameter flow-cytometric quantitation of epidermal growth factor receptor and c-erbB-2 oncoprotein in normal and neoplastic tissues of the female genital tract.

A novel multiparameter flow-cytometric method was used to quantify the expression of epidermal growth factor receptor (EGFR) and c-erbB-2 oncoprotein on 85 cryopreserved normal tissues (30 ovary, 29 endometrium, 16 cervix) and 67 carcinomas (31 ovarian, 18 cervical, 15 endometrial, 3 vulvar). Overexpression of the EGFR and c-erbB-2 oncoproteins was found in respectively 3/31 (9%) and 10/31 (32%) ovarian carcinomas, 13/18 (72%) and 7/18 (38%) cervical carcinomas, and 2/15 (13%) and 2/15 (13%) endometrial carcinomas. Oncoprotein expression was significantly higher in the malignant tumors (for all tumor sites) than in the corresponding normal tissues (P less than 0.034 for all combinations). Aneuploid tumors expressed levels of EGFR and c-erbB-2 oncoprotein significantly higher than those of DNA diploid tumors (P = 0.042 and P = 0.048, respectively). Oncoprotein could be detected in nearly all normal tissues: expression was higher in premenopausal than in postmenopausal patients (EGFR, P = 0.07; c-erbB-2, P less than 0.001). The present study supports the idea that EGFR and c-erbB-2 may play an important role in the autocrine, paracrine, and/or endocrine growth control and differentiation of normal tissues. Alteration in the expression of these oncoproteins is probably involved in malignant transformation and tumorigenesis.

Carcinoma↗
PubMed1991

Outbreak of human calicivirus gastroenteritis in a day-care center in Sydney, Australia.

Between January and March 1988, an outbreak of gastroenteritis occurred among children and staff at a day-care center in Sydney, New South Wales, Australia. Over an 11-week period, 53 persons had 101 episodes of gastroenteritis; some patients had 5 separate episodes. The principal etiologic agent in the outbreak, human calicivirus (HCV), was detected by electron microscopy in 32% of fecal specimens from children and staff members with symptoms but in only 8% of asymptomatic individuals (P less than 0.01). HCV was confirmed by both an enzyme immunoassay and solid-phase immune electron microscopy. HCV infection was a particular problem in infants, who had the highest age-specific attack rates, had the greatest symptomatic/asymptomatic infection ratio, and were most likely to have a second symptomatic episode. The mode of transmission of this virus was not identified, and extensive efforts to control the 11-week outbreak had little effect. Prolonged excretion of HCV by some symptomatic patients and high rates of asymptomatic infection may have contributed to the extended duration of the outbreak. HCV may be a common cause of gastroenteritis in children that is under-recognized because of insensitive methods of detection.

Australia↗
PubMed1991

Airline pilot incapacitation survey.

A survey, replicating one originally conducted by the International Federation of Airline Pilots' Associations (IFALPA) in 1967, was carried out to investigate the aetiology of inflight incapacitation on commercial flight decks. The questionnaire was constructed by IFALPA and distributed worldwide by its member associations. Since response to the questionnaire was voluntary, no control of the sample population was possible. The results indicate that 29% of the 4,345 respondents had been incapacitated at least once. As in 1967, gastro-intestinal symptoms accounted for the majority (58%) of incidents, other main causes being symptoms of nasal and sinus congestion ('blocked' ear and sinus pain), headaches, and faintness or general weakness. Of those who had experienced an incident of incapacitation, 48% claimed that safety was actually, or potentially, affected. However, when all respondents were asked whether they were concerned about safety in the event of incapacitation inflight (excluding take-off and landing), only 25% expressed concern. Slightly more pilots operating in three-man crews (50.5%) thought incapacitation affected the safety of the flight than those operating in two-man crews (45.3%).

Adult↗
PubMed1991

A new test of object decision: 2D silhouettes featuring a minimal view.

A new test of object decision in which a minimal view 2D silhouette of an object is presented together with 3 nonsense shapes has been administered to a consecutive series of patients with right and left hemisphere lesions. There was a significant deficit in the right hemisphere lesion group as compared with the left hemisphere group. It is concluded that this object decision test provides a measure of the integrity of pre-semantic perceptual processing systems.

Attention↗