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Biomedical subjects

Z Mehta

Publications and source records attributed to Z Mehta.

13 recordsLinked to original sources
PubMed1999

Sequence variants of the sarco(endo)plasmic reticulum Ca(2+)-transport ATPase 3 gene (SERCA3) in Caucasian type II diabetic patients (UK Prospective Diabetes Study 48).

AIMS/HYPOTHESIS: Type II (non-insulin-dependent) diabetes mellitus is a common heterogeneous metabolic disorder of largely unknown genetic aetiology. The sarco(endo)plasmic reticulum Ca(2+)-transport ATPase (SERCA) plays an important part in the glucose-activated beta-cell Ca(2+) signalling that regulates insulin secretion. Impaired function and expression of SERCA have been shown in islets of Langerhans from diabetic animal models and have also been associated with beta-cell apoptosis. Thus, the SERCA3 encoding gene is a plausible candidate for a primary pancreatic beta-cell defect. METHODS: In this study, the entire coding and the promoter regions of SERCA3 gene were screened by single-strand conformation polymorphism analysis in white Caucasian Type II diabetic patients. RESULTS: We found four rare missense mutations [Exon 4: Gln(108)-->His (CAG-->CAT), Exon 14: Val(648) -->Met (GTG-->ATG) and Arg(674)-->Cys (CGC--> TGC), and Exon 15: Ile(753)-->Leu (ATC-->CTC)]. The patients with Gln(108)-->His, Val(648)-->Met and Arg(674)-->Cys mutations, which may affect the E1P-E2P transition of SERCA3 during its enzyme cycle, had normal body weight with marked hyperglycaemia and beta-cell dysfunction. That is an unusual phenotype only found in 6 % of the Type II diabetic patients recruited for the UK Prospective Diabetes Study. In addition, five silent polymorphisms, six intron variants and two polymorphisms in the 3' untranslated region of exon 22 were found with similar frequency in diabetic and control subjects. CONCLUSION/INTERPRETATION: Our result suggests that in white Caucasians, the SERCA3 locus possibly contributes to the genetic susceptibility to Type II diabetes [Diabetologia (1999) 42: 1240-1243].

Calcium-Transporting ATPases↗
PubMed1996

Selective loss of verbal imagery.

This single case study of the ability to generate verbal and non-verbal imagery in a woman who sustained a gunshot wound to the brain reports a significant difficulty in generating images of word shapes but not a significant problem in generating object images. Further dissociation, however, was observed in her ability to generate images of living vs non-living material. She made more errors in imagery and factual information tasks for non-living items than for living items. This pattern contrasts with our previous report of the agnosic patient, M.S., who had severe difficulty in generating images of living material, whereas his ability to image the shape of words was comparable to that of normal control subjects. Furthermore, with regard to the generation of images of living compared with non-living material, M.S. shows more errors with living than nonliving items. In contrast, the present patient, S.M., made significantly more errors with non-living relative to living items. There appear to be two types of double dissociation which reinforce the growing evidence of dissociable impairments in the ability to generate images for different types of verbal and non-verbal material. Such dissociations, presumably related to sensory and cognitive processing demands, address the problem of the neural basis of imagery.

Adult↗
PubMed1996

Dissociable contributions of the two cerebral hemispheres to judgments of line orientation.

A previous study of the performance of men with chronic unilateral focal brain lesions (due to wartime missile injury) on a standard test of line orientation suggested a left hemisphere (LH) as well as a right hemisphere (RH) contribution to visuospatial processing. The present study was designed to fractionate the variables that could underlie this unexpected finding and thereby to tease out the mechanisms involved in LH as compared with RH processing. A simpler ("purer") version of the standard line orientation task was used, as were two other versions in which matching in an array and matching with distractors were measured. The findings confirmed the hypothesis of RH involvement in the purer task of metric measurement and suggested that the LH has an important role in keeping track decisions and updating decisions in more complex aspects of line orientation judgment.

Aged↗
PubMed1993

Patient history as a simple predictor of pelvic pathology in subfertile women.

The objective of this study is to determine in a group of subfertile women whether patient history can differentiate women with a healthy pelvis from those with endometriosis or adnexal adhesions. In this prospective study, consecutive subfertile women undergoing laparoscopy and tubal hydrotubation for the sole indication of subfertility were evaluated at the teaching hospital fertility unit. They had a minimum of 2 years subfertility. The main outcome measures were: patients' response to a 7-point physical symptom and medical history questionnaire, laparoscopic findings of endometriosis and adnexal adhesions quantified according to the American Fertility Society classification. Of 104 patients, 99 patients were retained in the analysis. Forty per-cent had endometriosis, 19% pelvic adhesions and 40% a normal pelvis. Severe dysmenorrhoea was the only symptom predictive for endometriosis (relative risk 1.7). Severe dysmenorrhoea, a vaginal discharge, past use of a coil and previous laparotomies were all predictive for pelvic adhesions (relative risks 2.1, 3.3, 2.1, 1.9, respectively). The relative risk increased with severity of the disease. Patients with moderate and severe adhesions were 4.2 and 5.3 times more likely to have severe dysmenorrhoea and a vaginal discharge than patients with a normal pelvis. Subfertile women giving a positive response to selected questions about their medical history are at increased risk of endometriosis and pelvic adhesions. Where resources are limited, such a system could be used to plan effective use of available diagnostic facilities.

Adnexal Diseases↗
PubMed1992

Selective loss of imagery in a case of visual agnosia.

Experiments were designed to examine the imagery abilities of an agnosic patient, M.S., who has consistently shown more severe deficits in recognizing visually, and in retrieving knowledge of living as compared with non-living items. Judgements of visual similarity were required for named objects and for object-pictures, as well as for the factual properties of these stimuli. The same disproportionate difficulty in processing living ('natural') objects was found in these tasks as well as in forced-choice recognition. In contrast, no deficit was found on analogous tasks concerned with word-shape similarities. These findings have a bearing on concepts of semantic memory.

Adult↗
PubMed1991

A role for the left hemisphere in spatial processing.

This study extended our recently reported evidence of a left hemisphere (LH) contribution to spatial processing on standard visuospatial tasks. The present investigation compared performance on these standard tasks with that on 'purer' experimental tasks. Two tasks of line orientation, two of shape rotation and a shape matching task were administered to 50 men with stable unilateral post-Rolandic missile injuries and 32 control subjects. A LH deficit was found on the standard task of line orientation but not the 'purer' task, suggesting that the LH plays a role in eliminating extraneous information, presented only in the standard test. As for shape rotation, the LH group was impaired on both tasks. On the shape matching task, both experimental groups were significantly slower than control subjects. It is proposed the LH makes an important contribution to mental rotation and the understanding of Euclidean geometrical shapes.

Aged↗
PubMed1989

Category-specificity and modality-specificity in semantic memory.

Studies of agnosia have revealed two apparently orthogonal dimensions along which knowledge may break down. In some cases, knowledge of specific categories (such as living things) seems lost, regardless of the modality being tested. In other cases, knowledge in specific modalities (such as vision) seems lost, regardless of the category of stimuli being tested. These different sets of phenomena suggest different organizations for knowledge in the brain, the first by category and the second by modality. Unfortunately, possible confoundings between category, modality, and difficulty level in the previous studies prevent us from drawing strong conclusions from these data. The present study was aimed at assessing the nature of the breakdown in the semantic memory of a prosopagnosic patient, by orthogonally varying category and modality, while assessing difficulty level. The findings do not implicate a simple categorical or modality-dependent organization of his knowledge, but rather an organization in which both category and modality play a role.

Adult↗
PubMed1989

Brown-Séquard syndrome associated with posttraumatic cervical epidural hematoma: case report and review of the literature.

Post-traumatic cervical epidural hematoma is an uncommon entity. A case is presented in which such a lesion developed after chiropractic manipulation of the neck. The patient presented with a Brown-Séquard syndrome, which has only rarely been reported in association with cervical epidural hematoma. The correct diagnosis was obtained by computed tomographic scanning. Surgical evacuation of the hematoma was followed by full recovery.

Accidents, Traffic↗
PubMed1987

A left hemisphere contribution to visuospatial processing.

Men with chronic, focal, unilateral missile injures of the brain--twenty-five with left hemisphere lesions (LH group) and twenty with right hemisphere lesions (RH groups)--and twenty-two control subjects were given two visuoperceptual and two visuospatial tests. The LH group was significantly impaired in relation to the control group on both the spatial tasks. A different pattern of dissociable perceptual and spatial deficits was found in the experimental groups: better preserved perceptual than spatial performance was observed more frequently in the LH group whereas the converse--relatively better spatial than perceptual performance--was more evident in the RH group. Double dissociations in performance on the two spatial tasks were found predominantly in the LH group. These findings suggest an important left hemisphere contribution to visuospatial processing and the possibility of a more focal representation of spatial abilities in the left hemisphere than in the right.

Aged↗