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Biomedical subjects

M Patel

Publications and source records attributed to M Patel.

At least 379 records · Page 21Linked to original sources
PubMed1992

Comparative effects of enalapril and nifedipine on renal hemodynamics in hypertensive renal allograft recipients.

The comparative effects of enalapril (E) and nifedipine (N) on renal hemodynamics were assessed in twenty-two moderately hypertensive, cadaveric renal transplant patients who were maintaining stable renal function. Fourteen patients were on cyclosporin (CSA) and eight were receiving azathioprine with prednisolone (AZA). In each patient effective renal plasma flow (ERPF) was determined four times, first baseline, second with E, third as another baseline after a washout period, and fourth with N; and renal vascular resistance (RVR) was derived in each. ERPF and RVR were significantly compromised in the CSA group (202 +/- 55 ml/min and 65 +/- 18 mmHg/ml/min) compared to the AZA group (302 +/- 99 and 43 +/- 15 respectively). During E therapy, RVR further increased in the CSA group to 82 +/- 37 while it decreased in the AZA group to 31 +/- 7 (both changes were significant when compared to their respective baseline values). N, on the other hand, only significantly lowered RVR in the AZA group. Furthermore, two patients, one from each group, developed acute reversible renal failure shortly after E therapy. However, both agents were effective in lowering blood pressure to a comparable degree in both groups. In conclusion, our data showed a somewhat less favourable renal hemodynamic response to short-term enalapril therapy in hypertensive renal transplant patients maintained on CSA. However, the significance of such hemodynamic changes for long-term renal function remains uncertain.

Adult↗
PubMed1992

An outbreak of hepatitis A: school toilets as a source of transmission.

An outbreak of hepatitis A associated with a Middle school involved 23 cases; 17 were pupils attending the Middle school, one was a teacher, one was a relative of a case, and four were from the associated First school, of whom three had siblings in the Middle school. The probable source case was a male pupil infected by a sibling who had contracted hepatitis A while abroad on holiday. A questionnaire survey and salivary IgG and IgM anti-HAV testing of the pupils demonstrated a statistically significant association between infection and the use of a changing room toilet for defecation. An inspection of the school showed that toilets lacked toilet paper, soap and hand towels. Advice was given to pupils, parents and staff on hygiene. Human normal immunoglobulin was administered to susceptible family contacts, pupils and staff at the school. The school outbreak might have been prevented if the source case for the school had been given immunoglobulin when his sibling developed hepatitis A.

Child↗
PubMed1992

Hematologic changes during and after cardiopulmonary bypass and their relationship to the bleeding time and nonsurgical blood loss.

The hemostatic dysfunction induced by cardiopulmonary bypass is due, in part, to a platelet dysfunction evidenced by a postoperative extension of the bleeding time; it leads to increased postoperative blood loss and morbidity. This study, which was conducted in 85 patients undergoing cardiopulmonary bypass, was designed to characterize the hematologic changes during and after cardiopulmonary bypass and to elucidate the relationships between these changes, the extension of the bleeding time, and the magnitude of the postoperative nonsurgical blood loss. Variables were measured before, during, and 2, 24, 48, and 72 hours after cardiopulmonary bypass. Univariate and multivariate analyses were performed with either the 2-hour postbypass bleeding time or the 4-hour postbypass blood loss as the dependent variables. The reversal of the extension of the bleeding time in the postoperative period was accompanied by a significant increase in the mean platelet volume and by a significant increase in the level of thromboxane B2 measured in the blood shed from the site of the bleeding time determination. The postoperative bleeding time correlated with the postoperative blood loss, and both parameters were dependent on the duration of cardiopulmonary bypass. In addition, the postoperative bleeding time correlated with the skin temperature and the plasma level of D-dimer, while the postoperative blood loss also correlated with temperature and the plasma levels of C3. These data establish a direct relationship between the postoperative bleeding time, the postoperative blood loss, and temperature. They indicate that the reversal of the postoperative extension of the bleeding time is due in part to rewarming and to the release of larger platelets into the circulation, and they suggest that hyperfibrinolysis and complement activation may play an important role in the cardiopulmonary bypass-induced platelet dysfunction.

Bleeding Time↗
PubMed1992

Regulation of c-fgr messenger RNA levels in U937 cells treated with different modulating agents.

The U937 cell line was used to investigate the induction of messenger RNA (mRNA) for the c-fgr mRNA tyrosine kinase proto-oncogene in cells of the monocyte-macrophage lineage. U937 cells were exposed to tumour necrosis factor-alpha (TNF-alpha), TNF-beta and transforming growth factor-alpha (TGF-alpha), alone and in combination with PMA and 1,25-dihydroxycholecalciferol (1,25-DHCC). TNF-alpha and TNF-beta, but not TGF-alpha, decreased the proliferation of U937 cells in a time- and dose-dependent manner, and both TNF-alpha and TNF-beta enhanced the response of U937 cells to PMA during the first 24 hr of treatment and to 1,25-DHCC over 72 hr. TNF-alpha induced a rapid increase in c-fgr mRNA levels within 4 hr, in contrast to slower induction by PMA and 1,25-DHCC. TNF-alpha and 1,25-DHCC together had an additive effect on c-fgr mRNA levels. In U937 cells exposed to PMA, c-fgr mRNA levels continued to increase over 72 hr. Levels of c-fgr mRNA induced by the various modulating agents did not correlate clearly with the changes in proliferation. Therefore, we suggest that although the c-fgr gene product may have a role in differentiation, the more significant role is likely to be in the fully differentiated macrophage.

Animals↗
PubMed1991

Structure-function relationships in the cysteine proteinases actinidin, papain and papaya proteinase omega. Three-dimensional structure of papaya proteinase omega deduced by knowledge-based modelling and active-centre characteristics determined by two-hydronic-state reactivity probe kinetics and kinetics of catalysis.

1. A model of the three-dimensional structure of papaya proteinase omega, the most basic cysteine proteinase component of the latex of papaya (Carica papaya), was built from its amino acid sequence and the two currently known high-resolution crystal structures of the homologous enzymes papain (EC 3.4.22.2) and actinidin (EC 3.4.22.14). The method used a knowledge-based approach incorporated in the COMPOSER suite of programs and refinement by using the interactive graphics program FRODO on an Evans and Sutherland PS 390 and by energy minimization using the GROMOS program library. 2. Functional similarities and differences between the three cysteine proteinases revealed by analysis of pH-dependent kinetics of the acylation process of the catalytic act and of the reactions of the enzyme catalytic sites with substrate-derived 2-pyridyl disulphides as two-hydronic-state reactivity probes are reported and discussed in terms of the knowledge-based model. 3. To facilitate analysis of complex pH-dependent kinetic data, a multitasking application program (SKETCHER) for parameter estimation by interactive manipulation of calculated curves and a simple method of writing down pH-dependent kinetic equations for reactions involving any number of reactive hydronic states by using information matrices were developed. 4. Papaya proteinase omega differs from the other two enzymes in the ionization characteristics of the common (Cys)-SH/(His)-Im+H catalytic-site system and of the other acid/base groups that modulate thiol reactivity towards substrate-derived inhibitors and the acylation process of the catalytic act. The most marked difference in the Cys/His system is that the pKa for the loss of the ion-pair state to form -S-/-Im is 8.1-8.3 for papaya proteinase omega, whereas it is 9.5 for both actinidin and papain. Papaya proteinase omega is similar to actinidin in that it lacks the second catalytically influential group with pKa approx. 4 present in papain and possesses a catalytically influential group with pKa 5.5-6.0. 5. Papaya proteinase omega occupies an intermediate position between actinidin and papain in the sensitivity with which hydrophobic interaction in the S2 subsite is transmitted to produce changes in transition-state geometry in the catalytic site, a fact that may be linked with differences in specificity in P2-S2 interaction exhibited by the three enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1991

Direct correlation of cytogenetic findings with cell morphology using in situ hybridization: an analysis of suspicious cells in bone marrow specimens of two patients completing therapy for acute lymphoblastic leukemia.

Bone marrow cells from two pediatric patients completing therapy for acute lymphoblastic leukemia were studied using in situ hybridization with an alpha-satellite DNA probe specific for chromosome 17. Morphologic analysis of the end-therapy specimens from each patient had shown small numbers (7.5%, 8.5%) of cells that were suspicious for residual or recurrent disease. These cells could not be morphologically or immunophenotypically distinguished with certainty from immature lymphoid cells (hematogones), which may be present normally, sometimes in increased numbers, in the bone marrow specimens of children. In situ hybridization with a probe to chromosome 17 was used because the leukemic cells from each patient had originally been shown to have an extra copy of this chromosome. In one patient, in situ studies showed a population of cells (106 of 1,000 cells) with three hybridization signals indicating trisomy 17, and thus residual/recurrent leukemia. In the other patient trisomy 17 could not be detected. Additional hybridizations to previously stained bone marrow aspirate smears permitted a direct correlation of the cytogenetic findings with the suspicious cells on a cell-to-cell basis. The questionable cells were identified, photographed, and then re-examined after hybridization. In one patient, 13 of 18 (72%) of the suspicious cells were found to have trisomy 17, whereas in the other patient 0 of 24 (0%) demonstrated an extra copy of this chromosome. These cases illustrate a clinical application of interphase cytogenetic analysis and demonstrate how this technology can be used for direct correlation of cytogenetic findings with cell morphology. This technique should prove useful for the detection of minimal residual disease and for lineage studies in leukemia and myelodysplasia.

Antigens, CD↗
PubMed1991

Use of hydroxyurea in chronic myeloid leukemia during pregnancy: a case report.

The concomitant occurrence of pregnancy and chronic myeloid leukemia is uncommon. The use of hydroxyurea in chronic myeloid leukemia during pregnancy is unknown. We report on a patient with chronic myeloid leukemia in whom hydroxyurea was used during pregnancy with a successful outcome for both mother and fetus.

Adult↗
PubMed1991

Evaluation of two assumptions: single straight line, and single normal distribution.

Using graphical and statistical approaches, Laszlo Endrenyi and Mayank Patel describe methods that answer two frequently asked questions: 'Can the data be characterized by a single straight line, or should a more complex model be invoked?' and 'Do the observations follow a single normal distribution, or is there evidence for deviations from this assumption, including the possibility of bimodality?" These methods complement those addressed in a recent Principles article by Dick Barlow.

Research Design↗
PubMed1991

Paravertebral muscle metastases from primary tongue and nasopharyngeal carcinomas.

Skeletal muscle metastases most commonly originate from primary lung, breast, genito-urinary and gastro-intestinal tract malignancies. They have been seen to arise from head and neck tumours. However, the only primary tumours reported to metastasize to muscle from this region have been oesophageal and thyroid neoplasms. We present two cases with paravertebral muscle metastases from primary tongue and nasopharyngeal carcinomas.

Carcinoma↗
PubMed1991

113Cd nuclear magnetic resonance (NMR) study of the inhibitory effect of methylvinylether/maleic acid (PVM/MA) copolymer on the alkaline phosphatase of Escherichia coli.

The inhibitory effect of PVM/MA copolymer on the alkaline phosphatase (AP) of E. coli was investigated. Kinetic studies indicated that enzyme inhibition was characterized by a reduction in both the Vmax and the Km. Addition of 1 mM zinc or magnesium ions to the reaction prevented inhibition of the enzyme by the copolymer. The inhibitory effect of the copolymer on alkaline phosphatase was also investigated using 113Cd NMR after exchange of the active center metal ions with 113Cd. The resulting Cd(II)6AP exhibited characteristic 113Cd resonances reflecting the environment of the A, B, and C metal binding sites of the enzyme's active center. Addition of copolymer resulted in a 113Cd NMR spectrum which indicated removal of 113Cd from the C site and formation of two distinct forms of the enzyme. Possible explanations for the 113Cd NMR results are discussed.

Alkaline Phosphatase↗
PubMed1991

Percutaneous iliac bone grafting of secondary alveolar clefts.

Secondary bone grafting of residual alveolar clefts has become an integral part of the comprehensive care of children born with facial clefting. Although indications and timing may remain somewhat controversial, bone grafting during the period of mixed dentition has gained widespread acceptance. A number of bone graft sites have been proposed; each has its enthusiastic proponents. We believe that cancellous bone harvested from the ilium provides optimal material to achieve successful alveolar bone grafting. Unfortunately, this site has been associated with significant morbidity, primarily pain, which can prolong a patient's hospitalization. We relate our experience from two centers encompassing 24 patients who underwent percutaneous harvesting of corticocancellous bone grafts from the ilium. With this method we were successful in obtaining adequate quantities of corticocancellous bone with the Craig bone biopsy needle regardless of the cleft size. Each patient was able to ambulate without difficulty within hours of surgery. We are currently performing alveolar bone grafting as an outpatient procedure employing this technique. In addition, we believe this method has particular usefulness in Third World countries.

Adolescent↗
PubMed1991

A new, sensitive graphical method for detecting deviations from the normal distribution of drug responses: the NTV plot.

1. A new graphical method was developed for the detection of deviations from the normal distribution. The approach took advantage of the similarity of graphical features of a graded dose-response relationship and a cumulative normal distribution. 2. The behaviour of the new normal test variable (NTV) plot was evaluated, in comparison with that of the probit plot and probability density functions (the generalization of histograms), for various assumed distributions. These included skewed distributions and composites of normal distributions with a variety of separations, ratios of peak sizes and widths. 3. The NTV approach generally detected deviations from the normal distribution more sensitively than the probit plot. 4. The NTV and probit plots may be able to identify biomadality by complementary approaches. 5. The characteristics of the three graphical representations were illustrated by a simulated sample from a composite of normal distributions and by an example of sparteine metabolism in 142 Cuna Amerindians.

Dose-Response Relationship, Drug↗
PubMed1991

Comparison of the new MicroScan Pos MIC Type 6 panel and AMS-Vitek Gram Positive Susceptibility Card (GPS-TA) for detection of high-level aminoglycoside resistance in Enterococcus species.

We compared the MicroScan Pos MIC Type 6 panel and AMS-Vitek Gram Positive Susceptibility Card (GPS-TA) to agar dilution screen plates for the detection of high-level aminoglycoside resistance in 182 enterococcal isolates. The specificity of the two commercial systems was 100%, with the exception of one susceptible isolate found to be streptomycin resistant by the Vitek system. The MicroScan and Vitek systems had comparable sensitivities for the detection of gentamicin resistance (90 and 95% respectively) and streptomycin resistance (85 and 78%, respectively). These results suggest that screening tests such as agar dilution screen plates, broth dilution, or disk diffusion should continue to be used to detect high-level gentamicin and streptomycin resistance.

Anti-Bacterial Agents↗
PubMed1991

The c-fgr proto-oncogene: expression in Epstein-Barr-virus-infected B lymphocytes and in cells of the myelomonocytic and granulocytic lineages.

The c-fgr proto-oncogene, which is a member of the c-src gene family, encodes the cytoplasmic tyrosine kinase p55c-fgr. Expression of the c-fgr gene is activated in human B lymphocytes following infection with Epstein-Barr virus, and the viral protein EBNA-2 is involved in mediating this effect. The only normal cells in which the c-fgr gene is known to be expressed are peripheral-blood granulocytes and monocytes, and tissue macrophages. In accordance with this, levels of c-fgr mRNA increase when the human promonocytic cell line U937 and the human myelomonocytic cell line HL60 are induced to differentiate. The enzyme activity and the expression pattern of p55c-fgr suggest that it is involved in regulating the responses of terminally differentiated granulocytes and monocytes to external stimuli, perhaps by controlling changes in cytoskeletal structure.

B-Lymphocytes↗
PubMed1991

Computed tomographic-angiographic findings within the first five hours of cerebral infarction.

BACKGROUND AND PURPOSE: Modern management of acute stroke necessitates early diagnosis. To this end, we sought to delineate the radiographic features of focal hemispheric infarction within 5 hours of ictus. METHODS: Fifty patients, ages 54-79, with ischemic strokes productive of at least hemiparesis underwent computed tomographic scanning and cerebral angiography (n = 38) or carotid ultrasound (n = 12). Radiographic lesions were characterized for location, size, and pathophysiology. RESULTS: Acute abnormalities, hypodensity, and mass effect were seen in 56% of scans and confirmed on a second scan 5-7 days later. Intracranial angiographic abnormalities occurred in 61% of patients: arterial occlusions in 45% and delayed arterial filling in 16%. Hemorrhagic infarctions occurred in 26% of second scans and were associated with mass effect (100%) and arterial occlusions (89%). Infarcts with hemorrhagic transformation were larger on both scans than those without (p = 0.001). Of four patients with infarctions in watershed territories on the scans, two had middle cerebral artery occlusions on angiography, thereby questioning the specificity of such scan lesions to low-flow states. CONCLUSIONS: We conclude that cerebral infarctions are often visible on early scans, but their locations may not be etiologically determinative. The infarcts associated with intracranial arterial occlusions (45%) were of thromboembolic origin, but, given current controversies as to the pathophysiology of lacunar and watershed infarctions, we cannot ascertain the etiology in the remainder. These findings are relevant to the new stroke therapies that require administration in the first hours after infarction.

Aged↗
PubMed1991

Characterization of a diuretic peptide from Locusta migratoria.

A diuretic peptide Locusta-DP, identified by its ability to increase cyclic AMP production in locust Malpighian tubules in vitro, has been isolated and characterized from whole heads of Locusta migratoria. The purified peptide stimulates fluid secretion by Malpighian tubules maximally in vitro. The primary structure of Locusta-DP was established as a 46 residue amidated peptide: MGMGPSLSIVNPMDVLRQRLLLEIARRRLRDAEEQIKANKDFLQQI-NH2. Locusta-DP has 48% sequence identity with Acheta-DP and 49% identity with Manduca-DH, and provides further evidence for the presence of a family of diuretic peptides in insects.

Amino Acid Sequence↗
PubMed1991

Cervical cytology in central Australian Aboriginal women.

Cervical smears were taken from 113 Aboriginal women who attended an Aboriginal community controlled health service in Alice Springs for gynaecological, obstetric or other unrelated conditions over a 6 month period. Nine women (8%) had cervical atypia and two (1.8%) had cervical intraepithelial neoplasia. These rates are similar to those observed among other population groups in larger Australian and overseas studies, as was the high prevalence of abnormal smears in women under 25 years of age (11% of this age group). Urban dwellers had a higher prevalence of abnormal smears (15%) compared with town camp and rural women (2%). This pilot study emphasises the importance of routine screening for central Australian Aboriginal women and identifies possible risk groups for further research.

Adolescent↗