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Biomedical subjects

S Prasad

Publications and source records attributed to S Prasad.

At least 145 records · Page 8Linked to original sources
PubMed1998

Optimisation of outpatient resource utilisation in cataract management.

PURPOSE: We assessed whether patients referred with a diagnosis of cataract require outpatient assessment before listing for surgery or whether the general practitioner could have direct access to the waiting list. We also studied whether pre-assessment clinics made a significant difference to management even when waiting times were long. METHODS: Data about patients referred with a diagnosis of cataract to the Oxford Eye Hospital and associated hospitals were collected. Seventy-five patients were prospectively studied and 100 patient records were retrospectively analysed. RESULTS: Twenty-six per cent of patients had a misdiagnosis or additional problems affecting management. Optometrists provided more information than general practitioners, but their diagnostic accuracy was equal (73% optometrists, 75% general practitioners). At the pre-assessment clinic pupil dilatation changed management in only 4% of patients. CONCLUSION: Listing patients on the basis of referral letters would be inappropriate in 1 in 4 patients. Pre-assessment clinics rarely picked up a clinically relevant change. Thus if outpatient consultation included a decision on the exact surgical plan including implant power, then pre-assessment clinics may not be necessary.

Cataract↗
PubMed1998

Sodium butyrate induces apoptosis and accumulation of ubiquitinated proteins in human breast carcinoma cells.

To investigate the possible relationship between apoptosis and the ubiquitin pathway we examined the patterns of ubiquitinated proteins in the human breast carcinoma MCF-7 cell line following induction of apoptotic death by sodium butyrate. Apoptosis in these cells was associated with internucleosomal DNA fragmentation and proteolytic cleavage of poly(ADP-ribose) polymerase. By dual in situ antiubiquitin immunofluorescence and chromatin DNA staining, we demonstrated that ubiquitin fluorescence was increased specifically in cells that underwent sodium butyrate-mediated apoptosis. The extent of ubiquitin incorporation into protein conjugates was examined in both adherent (not yet apoptotic) and floating (apoptotic) cell populations. We found that apoptotic cells exhibited enhanced intensity of ubiquitin-immunoreactive conjugates, whereas adherent cells did not. In addition, two-dimensional immunoblot analysis of proteins from apoptotic cells identified a set of isomeric ubiquitinated conjugates located at a pI range of 4. 2 - 4.6 and a Mr approximately of 30 kDa. These data indicate that the ubiquitin pathway may play a role in the sodium butyrate-induced apoptotic program in breast carcinoma cells.

Apoptosis↗
PubMed1998

Isolated Tessier no. 1 cleft of the nose.

We report 3 patients with isolated cleft or coloboma of the nose--an extremely rare occurrence. This entity belongs to no. 1 of Tessier's classification of craniofacial clefts. Excessive separation of the medial and lateral nasal processes of the frontonasal process may be the genesis of this condition. Management should address two points: the cleft and the associated malformations of the cartilaginous nasal framework.

Adult↗
PubMed1998

Mobilization of lead by calcium versenate and dimercaptosuccinate in the rat.

1. Calcium disodium ethylenediaminetetraacetate (CaNa2 EDTA) and meso-2,3-dimercaptosuccinic acid (DMSA) individually and in permutation-combination in various doses (0.1, 0.2 and 0.4 mmol/kg bodyweight) were investigated for their efficacy to mobilize lead from vital tissues into urine and faeces and to restore the lead-sensitive biochemical parameters in lead pre-exposed rats with a view to develop the most acceptable treatment regimen for lead poisoning with a minimal loss of endogenous essential elements. 2. The combined therapy was more effective than a single chelator treatment. 3. The combination of 0.2 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA caused a lower depletion of zinc, calcium and iron but possessed almost equal capability to that of 0.4 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA to produce urinary as well as faecal excretion of lead, to reduce the tissue burden of lead, including that of the brain, and to reverse lead-induced biochemical alterations. 4. The combination of 0.2 mmol/kg CaNa2EDTA + 0.4 mmol/kg DMSA has shown a definite improvement over previously reported combinations in terms of removal of lead from tissues, particularly the brain, restoration of urinary delta-aminolevulinic acid levels and a decrease in the loss of body zinc and is, therefore, recommended for the treatment of lead intoxication.

Animals↗
PubMed1998

Identification of keratins 18, 19 and heat-shock protein 90 beta as candidate substrates of proteolysis during ionizing radiation-induced apoptosis of estrogen-receptor negative breast tumor cells.

Induction of apoptosis in the estrogen-receptor negative MDA-MB-468 breast tumor cells has been demonstrated by treatments with cytotoxic agents and growth factors. Using these breast tumor cells, we studied ionizing radiation-induced apoptosis. 2D-PAGE of apoptotic cells indicated keratins 18, 19 and heat-shock protein 90 as candidate substrates of apoptosis-associated proteolysis. At the same time, a motif search revealed possible cleavage-sites in keratins 18, 19 (VEVD) and hsp-90 (DEED) that would yield polypeptides of molecular sizes observed experimentally by immunoblotting with specific antisera. This study provides evidence that the insoluble network of intermediate filament proteins of epithelial cells (keratins), and the associated proteins (heat-shock protein 90) constitute targets of caspase-mediated proteolysis during apoptosis triggered by ionizing radiation.

Amino Acid Sequence↗
PubMed1998

Experience in adult population in dengue outbreak in Delhi.

A dengue outbreak has recently hit the Indian capital. We studied the clinical profile of adult patients. Five hundred and sixty patients of dengue infection were admitted in a specially created ward according to the criteria laid down by WHO. Haematemesis (28.28%), epistaxis (26.78%) and malena (14.28%) were some of the common presentations. Similarly lymphadenopathy, especially cervical (30.89%), palatal rashes (26.96%) and hepatomegaly (23.75%) were the most commonly encountered findings on physical examination. Most of the cases were of dengue fever with haemorrhage and only 2.5% cases were classified under dengue haemorrhagic fever or dengue shock syndrome. The average hospital stay was 3.4 days but only 9.8 hours in the eleven patients who died, suggesting their late arrival in preterminal situation giving little time for resuscitation. Thrombocytopenia was not a feature and only 12.85% patients had platelet count less than 70,000/cmm. Most of the patients who were admitted with thrombocytopenia, showed normalization in their platelet counts in next few days. Serological examination demonstrated evidence of recent dengue infection in 41.17% patients. Few patients required blood or platelet concentrate transfusion. Eleven patients died, three due to DIC, one of intracranial haemorrhage and seven due to massive gastric haemorrhage. Rest of the patients recovered completely. Thus we can conclude that recent outbreak in Delhi was of dengue fever with haemorrhage and mortality was very low in patients who came early to the hospital.

Adolescent↗
PubMed1997

Influence of L-lysine and zinc administration during exposure to lead or lead and ethanol in rats.

Influence of lysine and zinc administration on the lead-sensitive biochemical parameters and the accumulation of lead during exposure to lead or lead and ethanol was investigated in rats. The lead exposure inhibited blood delta-aminolevulinic acid dehydratase (ALAD) activity, increased blood zinc protoporphyrin (ZPP), urinary delta-aminolevulinic acid (ALA), serum glutamic oxalacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), blood and tissue lead levels, and decreased blood and hepatic glutathione (GSH) contents. Some of these effects were enhanced on coexposure to ethanol. The simultaneous administration of lysine and zinc reduced tissue accumulation of lead and most of the lead-induced biochemical alterations irrespective of exposure to lead alone or lead and ethanol. The depletion of endogenous calcium and magnesium owing to lead or ethanol exposure was also prevented by co-administration of lysine and zinc.

Alanine Transaminase↗
PubMed1997

Cell death in the gastrulating chick embryo: potential roles for tumor necrosis factor-alpha (TNF-alpha).

We have examined the expression of TNF-alpha and its receptors, TNFR1 and TNFR2, during gastrulation in the chick embryo, and have investigated the possible role of this factor in the control of cell death at this early stage of development. TNF-alpha, immunoreactive at approximately 17 kD, was found both in vivo and in vitro, most intensely associated with the cell surface and cytoskeleton of endoderm cells. TNFR2 was especially immunoreactive in endoderm cells of the marginal zone. TNFR1 was found in nuclei throughout the embryo. Embryos also showed widespread expression of both the bcl-2 and Bax gene products, which are both associated with cell death pathways. Intact embryos in culture were sensitive to the addition of TNF-alpha (approx. 110 ng/ml), responding by significantly increasing the incidence of DNA fragmentation in cells from all tissues of the embryo. This effect was abrogated by immunological pre-absorption of the cytokine. Cultured cells from these embryos also responded to the addition of agonistic antibodies to TNF-alpha receptors by increasing DNA fragmentation. A similar response to TNF-alpha antiserum by cultured cells appeared to be related to a concomitant decrease in cell-substratum adhesion caused by the antibody. Decreased cell adhesion, induced non-specifically with anti-integrin antiserum, also resulted in increased DNA fragmentation. TNF-alpha, synthesized and secreted by the embryo itself, may be able to exert a paracrine effect on the incidence of cell death in tissues of the embryo, and the cell death process may be related to the expression of bcl-2 and Bax gene products. The influence of TNF-alpha may be exerted by the activation of cell death signalling pathways directly, or indirectly through perturbation of the cytoskeleton or of integrin-mediated cell adhesion.

Journal Article↗
PubMed1997

The effect of viral regulatory protein expression on gene delivery by human immunodeficiency virus type 1 vectors produced in stable packaging cell lines.

We describe the generation of stable human immunodeficiency virus type 1 (HIV-1)-packaging lines that constitutively express high levels of HIV-1 structural proteins in either a Rev-dependent or a Rev-independent fashion. These cell lines were used to assess gene transfer by using an HIV-1 vector expressing the hygromycin B resistance gene and to study the effects of Rev, Tat, and Nef on the vector titer. The Rev-independent cell lines were created by using gag-pol and env expression vectors that contain the Mason-Pfizer monkey virus (MPMV) constitutive transport element (CTE). Vector titers approaching 10(4) CFU/ml were routinely obtained with these cell lines, as well as with the Rev-dependent cell lines, with HeLa-CD4 cells as targets. The presence of Nef and Tat in the producer cell each increased the vector titer 5- to 10-fold. Rev, on the other hand, was absolutely essential for gene transfer, unless the MPMV CTE was present in the vector. In that case, by using the Rev-independent cell lines for packaging, Rev could be completely eliminated from the system without a reduction in vector titer.

Base Sequence↗
PubMed1997

Management options for solitary thyroid nodules in an endemic goitrous area.

An analysis of management of 546 cases of solitary thyroid nodules in an endemic area is presented. None of the evaluating procedures could effectively isolate benign from malignant disease. Of 508 cases considered clinically to be benign, 42 harboured malignancy on histological examination whereas of the 38 cases suspected clinically to be malignant, 21 were histologically benign. 131I-Thyroid scanning also lacked sensitivity in identifying malignant nodules since the prevalence of malignancy in cases which were 'cold' (44/316) was not significantly different from that amongst the 'uniform' cases (15/142). Fine-needle aspiration cytology, although the most sensitive and specific evaluating modality, did not decrease the number of operations for solitary thyroid nodules nor did it increase the incidence of malignancy amongst the operated cases, because of its limitations in differentiating benign from malignant follicular neoplasms. The conditions under which surgery was advocated are described.

Adenoma↗
PubMed1997

Chelation in metal intoxication LI: efficacy of amphipathic dithiocarbamates in mobilization of lead in the rat.

N-benzyl-D-glucamine dithiocarbamate (BG.DTC) and its analog, N-(4-methoxybenzyl)-D-glucamine dithiocarbamate (MeO-BG.DTC) which are effective chelators of cadmium were investigated for their efficacy to induce excretion of lead, to reduce tissue burden of lead and to reverse certain lead sensitive biochemical alterations in lead pre-exposed rats. These were quite effective in reducing hepatic and renal but not brain lead levels as reflected by the enhanced urinary and fecal excretion of lead and in partially restoring lead inhibited blood delta-aminolevulinic acid dehydratase activity. The introduction of a methoxy group at para-position of benzyl ring, unlike in case of cadmium, did not improve the lead chelating ability of the compound. The treatment with BG.DTC and MeO-BG.DTC caused depletion of endogenous essential elements such as zinc, copper and calcium as evidenced by their enhanced excretion and decreased tissue contents which were more marked in animals treated with the latter.

Animals↗
PubMed1997

Ophthalmology on the information superhighway: an introduction to the Internet.

Internet, e-mail, world wide web and the information superhighway have fast become part of the modern human vocabulary. How are we as ophthalmologists affected by this revolution and how can we utilise the enormous potential of this revolution? This article provides an overview of the practicalities and possibilities of this new medium.

Computer Communication Networks↗
PubMed1996

Role of transiently altered sarcolemmal membrane permeability and basic fibroblast growth factor release in the hypertrophic response of adult rat ventricular myocytes to increased mechanical activity in vitro.

One of the trophic factors that has been implicated in initiating or facilitating growth in response to increased mechanical stress in several tissues and cell types is basic fibroblast growth factor (bFGF; FGF-2). Although mammalian cardiac muscle cells express bFGF, it is not known whether it plays a role in mediating cardiac adaptation to increased load, nor how release of the cytosolic 18-kD isoform of bFGF would be regulated in response to increased mechanical stress. To test the hypothesis that increased mechanical activity induces transient alterations in sarcolemmal permeability that allow cytosolic bFGF to be released and subsequently to act as an autocrine and paracrine growth stimulus, we examined primary isolates of adult rat ventricular myocytes maintained in serum-free, defined medium that were continually paced at 3 Hz for up to 5 d. Paced myocytes, but not nonpaced control cells, exhibited a "hypertrophic" response, which was characterized by increases in the rate of phenylalanine incorporation, total cellular protein content, and cell size. These changes could be mimicked in control cells by exogenous recombinant bFGF and could be blocked in continually paced cells by a specific neutralizing anti-bFGF antibody. In addition, medium conditioned by continually paced myocytes contained significantly more bFGF measured by ELISA and more mitogenic activity for 3T3 cells, activity that could be reduced by a neutralizing anti-bFGF antibody. The hypothesis that transient membrane disruptions sufficient to allow release of cytosolic bFGF occur in paced myocytes was examined by monitoring the rate of uptake into myocytes from the medium of 10-kD dextran linked to fluorescein. Paced myocytes exhibited a significantly higher rate of fluoresceinlabeled dextran uptake. These data are consistent with the hypothesis that nonlethal, transient alterations in sarcolemmal membrane permeability with release of cytosolic bFGF is one mechanism by which increased mechanical activity could lead to a hypertrophic response in cardiac myocytes.

Animals↗