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Biomedical subjects

D Shah

Publications and source records attributed to D Shah.

At least 19 recordsLinked to original sources
PubMed2005

Structure and dynamics of polymer-grafted clay suspensions.

The structure and dynamics of polymer-grafted two-dimensional silicate layers in solution were investigated. The geometry of the individual silicate layers was examined by looking at both polarized and depolarized light scattering from dilute solutions, while higher-concentration systems were used to study the interaction and dynamics of polymer-grafted silicate layers in suspension. The form factor for an oblate ellipsoid was used to fit the polarized intensity profile, and values of a approximately 80 nm and b approximately 380 nm for the semi-axes were obtained. The 80 nm value compares reasonably with the dimensions of the polymer brushes grafted on the surface of the silicate layers. The modulus of the grafted silicate in solution, as determined by Brillouin scattering, is of the order of 10 GPa. The cooperative diffusion mechanism, typical of interacting polymer chains, is suppressed due to the high polymer osmotic pressure. The osmotic pressure is also responsible for the weak interpenetration of the densely grafted polymer chains on the surface of the silicate layers. The scattering data indicates that the polymer-grafted nanoparticles move via collective diffusion and experience significant decrease in mobility above their overlap concentration.

Journal Article↗
PubMed2004

No panacea for drainage after percutaneous nephrolithotomy.

BACKGROUND AND PURPOSE: The optimal postoperative drainage system for patients undergoing percutaneous nephrolithotomy (PCNL) has not yet been determined. Each of the different tubes available has theoretical advantages and disadvantages. The objective of this study was to determine if any one system of post-PCNL drainage has any significant advantage over the others. PATIENTS AND METHODS: Sixty patients were randomized to either a 24F Re-entry tube (Group 1), an 8F pigtail catheter (Group 2), or a double-J stent (Group 3) (N = 20 for all groups). The double-J stent patients also had an 18F Councill catheter as a nephrostomy tube, which was removed on the morning of postoperative day 1. The three groups were well-matched for age, stone size, operative time, and mean number of percutaneous tracts (P > 0.05 for all). Data collected included intraoperative findings, postoperative analog pain scores and narcotic usage, presence of extravasation on postoperative nephrostogram, presence of perinephric fluid on postoperative ultrasound scans, length of stay, and whether leakage from the nephrostomy site persisted more than 48 hours after tube removal. RESULTS: There were no statistically significant differences among the three groups in terms of change in hematocrit or number of patients requiring blood transfusion; in the incidence of tube blockage, extravasation, or presence of perinephritic fluid; or in complication rates, length of hospital stay, or persistent leakage after tube removal. There was a strong trend to less postoperative leakage with the 8F pigtail than the Reentry tube (P = 0.05). Postoperative analog pain scores and narcotic usage were equivalent for all three groups. Patients Groups 1 and 2 were free of all tubes sooner than patients in Group 3 (P < 0.001). CONCLUSIONS: This study did not demonstrate an overwhelming advantage of any one drainage system over the others. All three systems were equally tolerated by patients. There may be less chance of prolonged nephrostomy-site leakage with an 8F pigtail catheter.

Catheterization↗
PubMed2003

Severity of systemic lupus erythematosus with diffuse proliferative glomerulonephritis and the ineffectiveness of standard pulse intravenous cyclophosphamide therapy in Jamaican patients.

The majority of patients seen at the renal clinic of the University Hospital of the West Indies (UHWI) are of African descent. The case notes of patients with systemic lupus erythematosus (SLE) with class 4 nephritis and who were given standard pulse intravenous cyclophosphamide therapy during the period 1990-2000 were retrospectively reviewed. Primary outcomes were doubling of serum creatinine and development of end stage renal disease (ESRD). Secondary outcomes were return of proteinuria to normal and renal remission. A total of 117 patients had a renal biopsy for SLE nephritis at the UHWI between 1990 and 2000. Of the patients, 34 (29%) had diffuse proliferative glomerulonephritis (WHO class 4), of which 29 were reviewed. Twenty-two patients of 24 in whom it was measured (92%) had significant proteinuria at presentation. The 24-hour proteinuria was measured at final review in 16 patients and in 10 patients it went into complete remission. At the beginning of therapy, 24 patients (83%) had renal impairment. Of the 18 who had final creatinine values, the renal function returned to normal in eight patients (44%) and an additional six patients showed a significant improvement in renal function at final review. Six patients developed end stage renal disease (ESRD). The risk (95% confidence interval) of developing ESRD at one year was 16.2% (CI, 6.4-37.6) and at two years was 23.2% (CI, 10.0-48.5). There were three deaths, two from sepsis and one from heart failure. The one-year mortality (95% CI) was 8% (CI, 2.0-28.5), the two-year mortality was 15.6% (CI, 4.9-43.5) and the five-year mortality was also 15.6% (CI, 4.9-43.5). Intravenous pulse cyclophosphamide for Jamaican patients with SLE and diffuse proliferative glomerulonephritis is an ineffective form of treatment.

Adolescent↗
PubMed2003

A case of pulmonary lymphangioleiomyomatosis.

A case of pulmonary lymphangioleiomyomatosis (PLAM) occurring in a 48-year-old Jamaican female is presented. The clinical, radiological, and pathological findings are typical of this rare condition, and serve to emphasize the need for a high index of suspicion in order to make the diagnosis and commence therapy early in the course of the disease. The outlook for patients with PLAM continues to be poor.

Diagnosis, Differential↗
PubMed2003

Bilateral epididymal metastases from primary adenocarcinoma of the prostate.

A 65-year-old man diagnosed with adenocarcinoma of the prostate gland opted for hormonal manipulation and had bilateral orchiectomy. Histological evaluation showed tumour deposits in both epididymides. Despite the relatively common occurrence of adenocarcinoma of the prostate, epididymal metastasis is a rare occurrence. This case highlights the need for proper evaluation of the testes and para-testicular structures so that accurate staging of these tumours can be made.

Adenocarcinoma↗
PubMed2002

Penile involvement in Henoch-Schonlein purpura.

The authors report the case of a four-year-old boy who, having been diagnosed as having uncomplicated Henoch-Schonlein purpura, returned five days later with a new crop of lesions and sudden onset of engorgement and oedema of the penis. Testicular and scrotal involvement has been well documented in Henoch-Schonlein purpura but involvement of the penis alone has not been widely reported.

Acute Disease↗
PubMed2002

Action of MDMA (ecstasy) and its metabolites on arginine vasopressin release.

3,4-Methylenedioxymethamphetamine (MDMA) has been reported to cause hyponatraemia, which appears to result from inappropriate secretion of the antidiuretic hormone arginine vasopressin (AVP). After administration of a low dose of (R,S)-MDMA (40 mg) to eight healthy drug-free male volunteers, concentrations of AVP in plasma increased significantly at 1, 2, and 4 hours. Although no relation between plasma MDMA and AVP was found on an examination of the entire data set over the 24-hour study period, a statistically significant negative correlation was observed at 1 hour. As this occurred at a time when both AVP and MDMA concentrations were rising, it was postulated that a metabolite, or metabolites, could primarily be responsible for the increase in AVP. To test this hypothesis we examined the effect of MDMA and five of its metabolites, in the dose range 0.1-1,000 nM, on AVP release from the isolated rat hypothalamus. All compounds tested were found to increase AVP release (using 10 nM and 1,000 nM concentrations), with 4-hydroxy-3-methoxymethamphetamine (HMMA), the major metabolite of MDMA, being the most potent, and 3,4-dihydroxymethamphetamine (DHMA) the least potent. Each compound (1,000 nM), with the exception of DHMA, also enhanced the response to 40-mM potassium stimulation. Our findings confirm that metabolites of MDMA, in addition to the parent drug, contribute to AVP secretion in vitro. Further work will demonstrate whether this is also true in vivo.

Animals↗
PubMed2002

Type 2 diabetes mellitus and thyrotoxicosis presenting concurrently.

The symptoms of thyrotoxicosis and diabetes mellitus can be quite similar, and in patients presenting with diabetes, thyrotoxicosis could be missed unless specifically tested for. There are few reports of the two conditions presenting at the same time. We report on two such cases. In a patient who is diagnosed as having both conditions concurrently, an oral glucose tolerance test should be repeated after successful treatment of thyrotoxicosis before a diagnosis of diabetes mellitus is made.

Aged↗
PubMed2001

Association of surgical specialty and processes of care with patient outcomes for carotid endarterectomy.

BACKGROUND AND PURPOSE: Because there is considerable variation in practice patterns and outcomes for carotid endarterectomy (CE), there is a need to study the processes of care that are associated with adverse outcomes. The purpose of this study was to examine the impact of processes of care and surgical specialty on adverse outcomes for CE. METHODS: A retrospective cohort study based on a voluntary CE registry containing 3644 patients undergoing CE between April 1, 1997, and March 31, 1999, in New York hospitals was used in the study. A multivariable statistical model was used to identify significant independent patient risk factors and to examine the association of processes of care and surgical specialty with outcomes after adjustment for differences in patient risk factors. RESULTS: The overall adverse outcome (in-hospital death or stroke) rate was 1.84%. After adjustment for differences in 7 patient risk factors that were significantly related to adverse outcomes, the use of >/=1 specific processes of care (eversion endarterectomy, protamine, or shunts) was found to be associated with lower odds of an adverse outcome relative to patients undergoing CE without the processes (OR=0.42, P=0.006). Similarly, patients undergoing surgery performed by vascular surgeons had lower odds of experiencing an adverse outcome (OR=0.36, P=0.009). Processes of care and surgical specialty were highly correlated with one another. CONCLUSIONS: Processes of care and surgical specialty are significant interrelated determinants of adverse outcome for CE.

Aged↗
PubMed2001

Evidence in Escherichia coli that N3-methyladenine lesions induced by a minor groove binding methyl sulfonate ester can be processed by both base and nucleotide excision repair.

It has been previously reported that a neutral DNA equilibrium binding agent based on an N-methylpyrrolecarboxamide dipeptide (lex) and modified with an O-methyl sulfonate ester functionality (MeOSO(2)-lex) selectively affords N3-methyladenine lesions. To study the interaction of the neutral lex dipeptide with calf thymus DNA, we have prepared stable, nonmethylating sulfone analogues of MeOSO(2)-lex that are neutral and cationic. Thermodynamic studies show that both the neutral and monocationic sulfone compounds bind to DNA with K(b)'s of 10(5) in primarily entropy-driven reactions. To determine how the cytotoxic N3-methyladenine adduct generated from MeOSO(2)-lex is repaired in E. coli, MeOSO(2)-lex was tested for toxicity in wild-type E. coli and in mutant strains defective in base excision repair (tag and/or alkA glycosylases or apn endonuclease), nucleotide excision repair (uvrA), and both base and nucleotide excision repair (tag/alkA/uvrA). The results clearly demonstrate the cellular toxicity of the N3-methyladenine lesion, and the protective role of base excision glycosylase proteins. A novel finding is that in the absence of functional base excision glycosylases, nucleotide excision repair can also protect cells from this cytotoxic minor groove lesion. Interaction between base and nucleotide excision repair systems is also seen in the protection of cells treated with cis-diamminedichloroplatinum(II) but not with anti-(+/-)-r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2001

Perinatal correlates and neonatal outcomes of small for gestational age infants born at term gestation.

OBJECTIVE: We sought to examine the current perinatal correlates and neonatal morbidity associated with intrauterine growth failure among neonates born at term gestation. STUDY DESIGN: We compared 372 small for gestational age (SGA, birth weight <10th percentile) infants born at term gestation to 372 appropriate for gestational age controls (AGA, birth weight 10th to 90th percentile) matched by sex, race, and gestational age within 2 weeks. RESULTS: Compared with AGA controls, significant (P < .05) maternal risk factors for SGA status included single marital status (59% versus 53%), lower prepregnancy weight (144 +/- 41 lbs versus 153 +/- 40 lbs), lower weight gain during pregnancy (29 +/- 15 lbs versus 33 +/- 15 lbs), smoking (25% versus 17%), hypertension (14% versus 7%), and multiple gestation (9% versus 2%). Mothers of SGA infants were more likely to undergo multiple (>or=3) antenatal ultrasound evaluations (19% versus 7%), biophysical profile monitoring (11% versus 4%), and oxytocin delivery induction (28% versus 16%) (P < .05). Pediatrician attendance was more common among SGA deliveries (50% versus 37%, P < .05). SGA infants had significantly higher rates of hypothermia (18% versus 6%) and symptomatic hypoglycemia (5% versus 1%). These neonatal problems remained significant even when medical or pathologic causes of intrauterine growth failure, including pregnancy hypertension, multiple gestation, and congenital malformations, were excluded. CONCLUSION: Despite higher rates of pregnancy complications among mothers of SGA infants, the rates of neonatal adverse outcomes are low. However, SGA infants remain at risk for hypothermia and hypoglycemia and require careful neonatal surveillance.

Birth Weight↗
PubMed2001

Effect of gestational zinc deficiency on pregnancy outcomes: summary of observation studies and zinc supplementation trials.

The lack of a valid indicator precludes a true estimate of zinc deficiency in pregnancy in various populations. However, it is possible that mild to moderate deficiency (as assessed by available indicators) may be common in the developing world. Animal experiments indicate that zinc deficiency can result in adverse maternal and fetal consequences. Human data, particularly from prenatal zinc supplementation trials, has failed to document a consistent maternal or infant benefit on evaluated outcome measures including pregnancy induced hypertension, preterm/post-term labour, premature rupture of membranes, maternal infection, postpartum haemorrhage, perinatal mortality, congenital malformations and fetal growth and gestation. Preliminary data suggest a beneficial effect of prenatal zinc supplementation on infants' neurobehavioural development and immune function (evaluated by diarrhoeal and ARI morbidity incidence in the first year of life). Future research should focus on these functional consequences and congenital malformations (with adequate sample sizes), and simultaneously address the safety issue, particularly in relation to micronutrient interactions. In the light of the currently available information, routine zinc supplementation can not be advocated to improve pregnancy outcome.

Animals↗
PubMed2001

Cholelithiasis in a child--an unusual presentation of Wilson's disease.

A nine year old mentally retarded girl with moderate splenomegaly and ascites presented with chronic cholelithiasis. The presence of Kayser-Fleischer rings and low serum ceruloplasmin level confirmed the diagnosis of Wilson's disease. Cirrhosis of liver and recurrent episodes of hemolysis--these two common complications of Wilson's disease make an ideal setting for gall stone formation. Only three such cases have been reported worldwide and ours is the first case report from India. We suggest that cholelithiasis and splenomegaly in a child without evidence of congenital hemolytic disease should be taken as a suspect of Wilson's disease.

Child↗
PubMed2000

Differential pacing for distinguishing block from persistent conduction through an ablation line.

BACKGROUND: Because complete linear conduction block is necessary to minimize the recurrence of reentrant tachycardias such as typical atrial flutter, we investigated a simple technique to recognize a persistent gap or complete linear block. METHODS AND RESULTS: We prospectively evaluated cavotricuspid isthmus conduction in 50 patients (age 63+/-8 years, 43 men) after radiofrequency ablation. The distal and proximal bipoles of a quadripolar catheter placed close to the ablation line were successively stimulated during recording from the ablation line. We hypothesized that because the initial and terminal components of local potentials reflected activation at the ipsilateral and contralateral borders of the ablation lesion, a change to a more proximal pacing site without moving the catheter would prolong the stimulus to the initial component timing, whereas the response of the terminal component would depend on the presence of block or persistent conduction. A shortening or no change in timing of the terminal component would indicate block, whereas lengthening would indicate persistent gap conduction. The results were compared with previously described criteria for isthmus block. Ninety-two sites were assessed: 17 before and 75 after the achievement of complete isthmus block. The timing of the initial component was delayed by 19+/-9 ms, and the terminal component was advanced by 13+/-8 ms after block and delayed by 12+/-9 ms in case of persisting conduction. The sensitivity, specificity, and positive and negative predictive values for linear block were 100%, 75%, 94%, and 100%, respectively. CONCLUSIONS: An accurate assessment of isthmus block or persistent isthmus conduction is possible with this technique of differential pacing.

Aged↗