Biomedical subjects

S Patel

Publications and source records attributed to S Patel.

At least 577 records · Page 32Linked to original sources

PubMed1991

Effect of visual display unit use on blink rate and tear stability.

In the literature, there is evidence supporting the notion that visual display unit (VDU) use decreases the blink rate and possibly reduces the stability of the precorneal tear film. In this investigation the blink rate and tear stability were measured using noninvasive techniques, in relation to VDU use. In normal healthy subjects, the results show an average 5-fold drop in blink rate during VDU use but tear stability appears to be unaffected. During VDU use a significant relation was found to exist between the interval between blinks and the stability of the precorneal tear film.

Adolescent↗

PubMed1991

Early clinical experience with a minute ventilation sensor DDDR pacemaker.

UNLABELLED: The new DDDR pacemaker META DDDR utilizes a minute ventilation sensor based on transthoracic impedance measurements. The sensor determines the metabolic indicated interval, the atrioventricular (AV) delay and the postventricular atrial refractory period (PVARP). The baseline PVARP must be carefully selected to define nonphysiological tachycardias. If a P wave falls within the PVARP the pacemaker will automatically switch to the VVIR mode. This behavior prevents tracking of paroxysmal atrial tachyarrhythmias (PAT). Twenty-eight patients with sinus node dysfunction (n = 20), AV junction ablation (n = 5), complete or intermittent AV block (n = 3); who received a META DDDR pacemaker were studied. The mean age was 65 +/- 13 years. RESULTS: mode switching (reversion) to VVIR was observed in 57% of the patients. Forty-two percent had episodes of mode switching to VVIR during a stress test, four related to PAT, and seven to sinus tachycardia. Fifty percent had episodes of mode switching to VVIR during a 24-hour Holter, four related to PAT, three to retrograde P wave sensing, and two to sinus tachycardia. At the last follow-up, 20 of the 26 patients initially programmed to the DDDR mode remained in the DDDR mode, while five were reprogrammed to the DDD and one to the VVIR mode. Mode switching has a high sensitivity but a low specificity for PAT. It appears to be a useful approach to prevent rapid tracking of atrial tachyarrhythmias. Careful PVARP programming is critical to appropriate reversion behavior, but further modifications of the algorithm are needed to improve its performance.

Aged↗

PubMed1991

Iris colour and the influence of local anaesthetics on pre-corneal tear film stability.

Using non-invasive methods we report here that the stability of the pre-corneal tear film is lower in the brown eye than in the blue eye. The average stability in the blue eye is 15.8 sec (SD +/- 5.8) and in the brown eye it is 12.3 sec (SD +/- 2.9). On average, instillation of topical anaesthetics, benoxinate hydrochloride (0.4%) or amethacaine hydrochloride (0.5%), depress the stability of the pre-corneal tear film in blue eyes but not in brown eyes.

Administration, Topical↗

PubMed1991

Rapid culture confirmation of herpes simplex virus by a monoclonal antibody-based enzyme immunoassay.

Rapid confirmation of herpes simplex virus (HSV) is essential in many clinical settings. Viral isolation in cell culture is the standard method for diagnosing HSV infection, with confirmation by specific immunological staining. The performance of the Rapid Absorbent Matrix Pad (RAMP) HSV culture confirmation test was evaluated with specimens obtained from 71 patients with suspected HSV infection and inoculated into African green monkey kidney cell lines. Forty-one culture-positive specimens were confirmed to be HSV by both the RAMP HSV test and the Bartels HSV immunoperoxidase test. Thirty immunoperoxidase-negative specimens were also negative in the RAMP HSV test. The sensitivity and specificity of the RAMP HSV test were 100%. Twelve specimens positive for cytomegalovirus, adenovirus, or enterovirus tested negative by the RAMP HSV test. Thus, the RAMP HSV test was faster than, easier to perform than, as sensitive as, and as specific as other well-documented confirmation methods.

Antibodies, Monoclonal↗

PubMed1991

The Golgi sorting domain of coronavirus E1 protein.

The coronavirus E1 membrane protein is confined to the Golgi after it is expressed in cells either by viral infection or via injection of synthetic RNA. We have investigated the features of the protein responsible for intracellular sorting and found that a C-terminal deletion of only 18 amino acids results in its transport to the plasma membrane. However, we have previously shown that this C-terminal region alone is not sufficient for Golgi retention. When E1 was fused to a cell-surface protein, Thy-1, the resulting molecule was retained in the Golgi. Various mutated forms of E1 whose destinations were the ER, cell surface or lysosomes were also fused to Thy-1, and in each case the fusion was sorted according to its E1 component alone. We argue that, in contrast to sorting signals for other membrane compartments, Golgi retention of E1 is not due to a single short peptide sequence. Instead, the Golgi 'signal' of E1 appears to require for its expression a domain comprising most of the sequence of the protein.

Amino Acid Sequence↗

PubMed1991

Amniotic fluid embolism during epidural anesthesia for cesarean section.

A survivor of a clinically severe presentation of amniotic fluid embolism during cesarean section performed under epidural anesthesia is presented. Some general pathophysiologic features of amniotic fluid embolism are discussed in the context of presented case: seizures as a first sign of amniotic fluid embolism, heart failure and coagulopathy. In addition we discuss the management of the epidural catheter in coagulopathy in the presented case.

Adult↗

PubMed1991

Determination of the rate of DNA synthesis of human tumor cells obtained by fine needle aspiration. Comparison of flow cytometry and an immunoperoxidase method for the detection of thymidine analogue incorporation.

Two methods of detecting thymidine analogue incorporation by lymphoma, leukemia and myeloma cells obtained by fine needle aspiration (FNA) are described. In one method, cells which have been incubated with the thymidine analogue iododeoxyuridine (IDURD) were exposed to primary monoclonal anti-IDURD antibody and a fluorescein-labeled linking antibody. The fluorescence of the antibody-labeled cells, which had synthesized DNA and incorporated the analogue, was detected by flow cytometry (FCM). In a second method, the cells that incorporated the analogue were detected on glass slide Cytospin preparations by an immunoperoxidase (IP) technique. The IDURD labeling index (LI), as determined by both FCM and IP staining, was compared to the percentage of cycling (S + G2/M) cells as determined by acridine-orange FCM. The data indicate that the IP method is reliable and correlated strongly with FCM determination of LI, percentage S-phase and lymphoma grade. Given the low cost and wide availability of IP technology, the IP method may be desirable for laboratories wishing to supplement cytology reports with cell cycle data.

Biopsy, Needle↗

PubMed1991

A pre-eclamptic-like syndrome associated with hypothyroidism during pregnancy.

Hypothyroidism presenting during pregnancy is rare, probably due to the lower incidence of hypothyroidism during the reproductive years, and because myxoedema causes anovulatory cycles. We report an unusual case of hypothyroidism during a 34-year-old woman's fifth pregnancy, complicated by hypertension, oedema, pericardial effusion and severe nephrotic syndrome. This is the first report of renal biopsy abnormalities under these circumstances. Review of the literature regarding hypothyroidism presenting during pregnancy leads us to suggest that hypothyroidism during pregnancy may mimic pre-eclampsia.

Adult↗

PubMed1991

Cytotoxic and proliferative functions of T lymphocyte clones derived very shortly after allogeneic bone marrow transplantation.

In a search for mechanisms of potential graft-versus-leukaemia (GVL) activity after allogeneic bone marrow transplantation (BMT), peripheral lymphocytes from five patients (four chronic myeloid leukaemia, one acute lymphoblastic leukaemia) 24-39 days post-transplant were precultured with pretransplant host leukaemia cells and then cloned by limiting dilution with interleukin-2 (IL-2). Clones obtained were exclusively CD3+ CD56-, carried the alpha/beta form of the T cell receptor for antigen, and were mostly (88% of 138) CD4+. None of 143 clones, including CD8+ clones, convincingly lysed host pretransplant cells, although 35 (24.5%) manifested lytic potential in lectin-mediated cytotoxicity assays. Measuring the proliferative responses of 118 of these clones in the presence of exogenous IL-2 revealed that a small number of clones reacted more strongly to host leukaemia than to unrelated leukaemias or B lymphoblastoid cell lines. In the two cases tested, the donor's untransplanted lymphocytes cloned under the same conditions as post-transplant cells did not generate any clones reacting preferentially with host leukaemia cells. These results may suggest that some T cells appearing shortly after allogeneic BMT could potentially mediate anti-leukaemia activity not associated with cytolysis of target cells.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1991

Sonographic gallstone patterns are of value in predicting the outcome of biliary lithotripsy.

The purpose of our study was to determine whether the qualitative features of gallstones, as expressed by their sonographic image, are related to the degree of fragmentation by shock-wave lithotripsy and the rate of stone clearance. The sonographic stone images of 73 patients with 1-3 uncalcified gallstones, followed for at least 1 yr after extracorporeal shock-wave lithotripsy, were analyzed and categorized by three independent observers into two distinct groups: type I--crescent to disc shape with gradual attenuation of echoes, and type II--rim-shape with abrupt shadowing. The degree of fragmentation and rate of stone clearance were significantly greater for type I stones than for type II stones. For all subjects, 1 yr after lithotripsy, 56% (27/48) of type I stones and 12% (3/25) of type II stones had cleared completely (p less than 0.0005). The clearance rate for solitary type I stones was 63% (20/32) versus 14% (2/14) for type II stones (p less than 0.005). Our observations suggest that sonographic analysis of stone patterns might help in predicting success, and contribute to greater cost-effectiveness of biliary extracorporeal shock-wave lithotripsy.

Bile Duct Diseases↗

PubMed1991

Congenital cyst of common bile duct: an unusual cause of obstructive jaundice.

Congenital cysts, sometimes referred to as nonparasitic biliary cysts, are not unusual findings in the liver parenchyma, but they have not been previously described in the common bile duct. This clinical report describes a 41-year-old woman with obstructive jaundice that was caused by congenital cysts. The patient had obstruction of the middle portion of the common bile duct; therefore the major differential diagnostic considerations were cholangiocarcinoma, cancer of the pancreas, or true biliary cysts. Congenital cysts, retention cysts, and neoplastic cysts cannot be differentiated from other true cysts preoperatively. Diagnosis can only be established by microscopic examination after surgical excision.

Adult↗

PubMed1991

Pharmacologic models of Alzheimer's disease.

The disruption of multiple neurotransmitter systems in Alzheimer's disease plays an important role in the pathophysiology of cognitive and behavioral disturbances associated with the illness. The central cholinergic system is significantly disrupted in a fashion that correlates with cognitive impairment. This article describes drugs, such as scopolamine, that selectively affect the cholinergic system and model aspects of Alzheimer's disease phenomenology in both animals and humans. Drugs that induce cognitive changes but whose chemical mechanisms are not well understood are presented as alternative pharmacologic models of Alzheimer's disease.

Acetylcholine↗

PubMed1990

Dental caries and periodontal disease in Papua New Guinea.

Last year I spent my elective in Papua New Guinea. I surveyed the prevalence of dental caries and periodontal disease among the Papua New Guineans and found that rates of disease were higher than those found in earlier studies. Changing diet, poor oral hygiene and a chronic shortage of trained dental staff are the main culprits.

DMF Index↗

PubMed1990

In vivo characterisation of novel efficacious muscarinic receptor agonists.

Although a number of muscarinic agonists have been used in clinical trials for Alzheimer's Disease, many of these compounds are low in potency and have only limited intrinsic efficacy. The present study describes four non-quaternary oxadiazole based muscarinic agonists from a quinuclidine and a 1-azanorbornane series. These displayed up to 1000 fold higher affinity than arecoline and were efficacious muscarinic agonists at cortical receptors. All four compounds produced peripherally mediated salivation and centrally mediated hypothermia at doses 50-50,000 fold lower than arecoline. The most potent was L-670,548, the methyl oxadiazole in the 1-azanorbornane series, which had an ED50 of 0.0016 mg/kg on the hypothermia model. This derivative was also the most potent compound in ex vivo binding studies (ED50 0.0069 mg/kg) and showed excellent brain penetration (3.8% of the administered dose). These derivatives are the first non quaternary efficacious agonists which show good penetration into the CNS (central nervous system), and will prove useful tools in understanding the role of muscarinic receptors in CNS function.

Animals↗

PubMed1990

Structural, functional, and antigenic differences between bovine heart endothelial CD36 and human platelet CD36.

Endothelial cell CD36 (glycoprotein IV) has been purified from bovine heart tissue by detergent partitioning and immunoaffinity chromatography. Bovine CD36 differs from human CD36 in its apparent mass (85 versus 88 kDa), primary structure, and immunological cross-reactivity. Of the 18 N-terminal residues identified, 17 conformed to the human CD36 sequence. Mouse monoclonal antibodies E-1 and 8A6 defined bovine- and human-specific epitopes, respectively. Because human CD36 has been identified as a receptor for erythrocytes infected with the malaria parasite Plasmodium falciparum, we examined the ability of bovine CD36 to bind infected erythrocytes. Bovine CD36, unlike human CD36, did not bind infected erythrocytes, suggesting that human CD36-specific structural features are responsible for recognition of the infected erythrocyte ligand.

Amino Acid Sequence↗

PubMed1990

Relative tumor initiating activity of benzo[a]fluoranthene, benzo[b]fluoranthene, naphtho[1,2-b]fluoranthene and naphtho[2,1-a]fluoranthene on mouse skin.

The tumor-initiating activities of benzo[a]fluoranthene (BaF), benzo[b]fluoranthene (BbF), naphtho[1,2-b]fluoranthene (NbF) and naphtho[2,1-a]fluoranthene (NaF) were evaluated on the skin of female CD-1 mice. Each of these polycyclic aromatic hydrocarbons was assayed at total initiation doses of 1.0 and 4.0 mumol/mouse. These hydrocarbons were applied in 10 subdoses administered every other day. Promotion commenced 10 days after the last initiator dose and consisted of thrice weekly application of 2.5 micrograms of tetradecanoylphorbol acetate for 20 weeks. BbF was the most potent tumor initiator inducing a 100% incidence of tumor-bearing mice with an average of 8.5 tumors per mouse at a total initiator dose of 1.0 mumol. NaF was slightly more active as a tumor initiator than either NbF or BaF. NaF induced a 90% incidence of tumor-bearing mice with an average of 5.9 tumors per mouse at a total initiator dose of 1.0 mumol. BaF and NbF at a total initiator dose of 4.0 mumol exhibited similar tumor-initiating activity with both inducing a 90% incidence of tumor-bearing mice with an average of 4.3 and 6.6 tumors per mouse, respectively. However, at a total initiator dose of 1.0 mumol, BaF and NbF induced a 95% and 65% incidence of tumor-bearing mice with an average of 3.3 and 2.5 tumors per mouse, respectively.

Animals↗

PubMed1990

Comparison of immunocytochemical and biochemical assays for estrogen receptor in fine needle aspirates and histologic sections from breast carcinomas.

An immunocytochemical assay using a monoclonal antibody specific for estrogen receptor (ER-ICA) was performed on needle aspirates and on histologic sections (mastectomy and biopsy specimens) from 55 patients with breast cancer. A total of 82 ER-ICAs were performed, with matched cytologic and histologic specimens in 27 patients, cytology alone in 15, and histology alone in 13. ER-ICA results were described by a histochemical score (H score) based on intensity-weighted percentages of staining cells. The H scores were compared with results of sucrose density gradient (SDG) analysis of histologic specimens (mastectomy, resection, or biopsy). An H score greater than or equal to 10 and an SDG value greater than or equal to 10 fmol/mg protein were considered positive. The sensitivity of cytologic ER-ICA was 94%, the specificity 100%. The sensitivity of histologic ER-ICA was 67%, the specificity 90%. Correlating cytologic H score with Black's nuclear grade showed that grade 1 (the most anaplastic) carcinomas demonstrated the lowest H scores (mean, 7.3 +/- 29.8), whereas the highest H scores were noted in grade 3 tumors (mean, 150.0 +/- 88.1). Both SDG and ER-ICA showed ER values to be lower in premenopausal than postmenopausal women. There was no correlation between H score and presence of axillary nodal metastases or tumor size. An overall good correlation was demonstrated between immunohistochemical methods and biochemical analysis.

Biopsy, Needle↗

PubMed1990

Modulation of experimentally induced epilepsy by intracerebral grafts of fetal GABAergic neurons.

Systemic administration of pilocarpine to rats induces seizures that resemble complex partial epilepsy in humans. Susceptibility to these seizures is increased by lesion of the GABAergic striatonigral projection. Transplantation of fetal GABAergic neurons, but also of control non-GABAergic tissue, to the deafferent substantia nigra can reduce such lesion-increased seizure susceptibility. These observations are consistent with prior evidence that GABAergic basal ganglia outflow plays an important role in controlling the spread of seizures, and raise the possibility that intracerebral grafts may be of use for therapy of medically-unresponsive epilepsies.

Animals↗