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Biomedical subjects

H Patel

Publications and source records attributed to H Patel.

At least 145 records · Page 8Linked to original sources

Where do children go? Comparing the after-hours availability of family physicians and primary care pediatricians in four Canadian cities.

OBJECTIVE: To describe and compare family physicians' and pediatricians' after-hours availability for pediatric care in four Canadian cities. DESIGN: Cross-sectional telephone survey. SETTING: Winnipeg, Toronto, Ottawa, and Montreal pediatric and family practices. PARTICIPANTS: All primary care pediatricians and an equal number of family physicians randomly selected from the membership list of the College of Family Physicians of Canada were matched by postal code. Sixty-four (10%) of 282 family physicians and 296 primary care pediatricians were excluded, most because no office telephone number was found. MAIN OUTCOME MEASURES: "After hours" was defined as between 1800 and 0700 hours on weekdays and 0900 to 2400 hours on weekend days. Outcomes included demographics, year of graduation, day of call, time of call, and availability of physician. RESULTS: Availability varied markedly by city rather than by physicians were available after hours: 92.4% in Winnipeg, 56.0% in Toronto, 65.5% in Ottawa, and 26.9% in Montreal. Winnipeg, Toronto, and Montreal showed no significant differences between specialties in availability. Only Ottawa pediatricians were significantly more available than family physicians when age was taken into account (adjusted relative risk = 2.17, 95% confidence interval = 1.51 to 3.12). Stratified analysis showed no differences by day of call, time of call, or physicians' sex. Physicians graduating before 1975 in both groups tended to be more available in all cities than younger physicians. CONCLUSIONS: Regional differences appear to influence after-hours availability more than specialty. Older physicians from both groups were more available than younger physicians.

Child↗

Warfarin and epistaxis: should warfarin always be discontinued?

The object of this study was to determine whether warfarin could be safely continued in patients with epistaxis if the International Normalized Ratio (INR) was within the suggested therapeutic range. Twenty patients on warfarin treatment were compared with controls, matched for age and sex. Local measures for the control of epistaxis were undertaken appropriately in all the patients. In the warfarin group 17 patients (85%) did not discontinue warfarin as the INR was within the suggested range. There were no additional bleeding complications or failure of epistaxis control due to continuation of warfarin. There was no significant difference in the mean hospital stay between the warfarin and non-warfarin groups. It is concluded that warfarin can be continued safely in patients with epistaxis, in appropriate circumstances, and that the policy of stopping warfarin routinely in all patients with epistaxis should be reconsidered.

Aged↗

Expression of recombinant human serum amyloid A in mammalian cells and demonstration of the region necessary for high-density lipoprotein binding and amyloid fibril formation by site-directed mutagenesis.

Site-directed mutagenesis of the acute-phase human serum amyloid A (SAA1 alpha) protein was used to evaluate the importance of the N-terminal amino acid residues, namely RSFFSFLGEAF The full-length cDNA clone of SAA1 alpha (pA1.mod.) was used to create two mutations, namely Gly-8 to Asp-8 and an 11 amino acid truncation between Arg-1 and Phe-11 respectively. Wild-type and mutant cDNAs were expressed in Chinese hamster ovary (CHO) cells under the control of the human cytomegalovirus promoter, which resulted in the secretion of the processed proteins into the culture media. Wild-type recombinant human SAA (rSAA) protein was shown to have pI values of 6.0 and 6.4, similar to the human SAA isoform SAA1 alpha and SAA1 alpha desArg found in acute-phase plasma. N-terminal sequencing of 56 residues confirmed its identity with human SAA1 alpha. The total yield of wild-type rSAA measured by ELISA was between 3.5 and 30 mg/l. The two mutations resulted in reduced expression levels of the mutant SAA proteins (3-10 mg/l). Further measurements of rSAA concentration in lipid fractions of culture medium collected at a density of 1.21 g/ml (high-density liporotein; HDL) and 1.063-1.18 g/ml (very-low-density lipoprotein/low-density lipoprotein; VLDL/LDL) showed that 76% of the wild-type protein was found in the HDL fraction and the remaining 24% in the infranatant non-lipid fraction. In contrast the relative concentration of mutant rSAA in HDL and infranatant fractions was reversed. This is consistent with the previously proposed involvement of the 11 amino acid peptide in anchoring. SAA protein on to HDL3 [Turnell, Sarra, Glover, Baum, Caspi, Baltz and Pepys (1986) Mol. Biol. Med. 3, 387-407]. Wild-type rSAA protein was shown to from amyloid fibrils in vitro under acidic conditions as shown by electron microscopy, and stained positive with Congo Red and exhibited apple-green birefringence when viewed under polarized light. Under the same conditions mutSAA(G8D) and mutSAA delta 1-11 did not form amyloid fibrils. In conclusion, replacement of Gly-8 by Asp-8 or deletion of the first 11 amino acid residues at the N-terminus of rSAA diminishes its capacity to bind to HDL and decreases amyloid fibril formation.

Amyloid↗

Characterization of the electrostatic perturbation of a catalytic site (Cys)-S-/(His)-Im+H ion-pair in one type of serine proteinase architecture by kinetic and computational studies on chemically mutated subtilisin variants.

We have used two structurally well-characterized serine proteinase variants, subtilisins Carlsberg and BPN', to produce (Cys)-S-/(His)-Im+H ion-pairs by chemical mutation in well defined, different, electrostatic microenvironments. These ion-pairs have been characterized by pH-dependent rapid reaction kinetics using, as reactivity probes, thiol-specific time dependent inhibitors, 2,2'-dipyridyl disulfide and 4,4'-dipyrimidyl disulfide, that differ in the protonation states of their leaving groups in acidic media, computer modelling and electrostatic potential calculations. Both ion-pairs possess nucleophilic character, identified by the striking rate maxima in their reactions with 2,2'-dipyridyl disulfide in acid media. In the Carlsberg enzyme, the (Cys220)-S-/(His63)-Im+H ion-pair is produced by protonic dissociation with pKa 4.1 and its reactivity is not perturbed by any detectable electrostatic influence other than the deprotonation of His63 (pKa 10.2). In the BPN' enzyme, the analogous, (Cys221)-S-/(His64)-Im+H ion-pair is produced by protonic dissociation with pKa 5.1 and its reactivity is affected by an ionization with pKa 3.5 in addition to the deprotonation of His64 (pKa > or = 10.35). It is a striking result that calculations using finite difference solutions of the Poisson-Boltzmann equation provide a value of the pKa difference between the two enzyme catalytic sites (0.97) in close agreement with the value (1.0) determined by reactivity probe kinetics when a protein dielectric constant of 2 is assumed and water molecules within 5 A of the catalytic site His residue are included. The pKa difference is calculated to be 0.84 when the water molecules are not included and a protein dielectric constant of 20 is assumed. The calculations also identify Glu156 in the BPN' enzyme (which is Ser in the Carlsberg enzyme) as the main individual source of the pKa shift. The additional kinetically influential pKa of 3.5 is assigned to Glu156 by examining the non-covalent interactions between the 2-pyridyl disulfide reactivity probe and the enzyme active centre region.

2,2'-Dipyridyl↗

Failure of implementation of the National Heart Foundation of New Zealand guidelines for the management of dyslipidaemia.

AIMS: We examined the outcome of patients at high absolute risk of coronary events who had been discharged from the Green Lane Hospital risk factor clinic before publication of the 1993 National Heart Foundation of New Zealand (NHF) guidelines for management of dyslipidaemia. METHODS: Consecutive patients who had been discharged >12 months previously were followed up by general practitioner and patient questionnaires. Patients were categorised according to risk of a coronary event over 10 years. Ideal lipid levels (cholesterol <5.2 mmol/L, high-density lipoprotein (HDL) cholesterol >1 mmol/L, total:HDL cholesterol ratio <5) and 'acceptable' lipid levels (cholesterol <6.5 mmol/L for high risk, <7.5 for moderate risk, <8 in men and <8.5 in women at mild or low risk) were defined according to the NHF guidelines. RESULTS: Of the 270 patients, 55.6% were at very high risk, 25.5% at high risk, 10.4% at moderate risk, 3.8% at mild risk and 0.7% at low risk. Twenty-four percent of patients were managed on diet alone at clinic discharge and 18% at follow up of 32+/-12 months. Total cholesterol (6.39 mmol/L), HDL cholesterol (1.22 mmol/L) and the total:HDL cholesterol ratio (5.71) were unchanged from discharge. In the very high risk group ideal lipid levels were achieved in only 12% at discharge and 7% at follow up. The corresponding figures for achievement of acceptable lipids at discharge compared with follow up were 48% and 39% for the high risk group, 88% and 79% for the moderate risk group and 93% and 93% for the mild risk group. The corresponding figures for achievement of ideal lipids were 4% and 8% for the high risk group, 0% and 5% for the moderate risk group and 7% and 7% for the mild risk group. CONCLUSIONS: Lipid levels achieved during clinic visits were maintained long term, but there were no improvements following publication of the NHF guidelines. Continued efforts are needed to increase awareness and implementation of the guidelines, particularly in patients at high risk. Removal of the restrictions on prescription of lipid modifying agents by general practitioners and improved interchange between general practitioners and specialists should greatly improve these outcomes.

Family Practice↗

Recent corticosteroid use and the risk of complicated varicella in otherwise immunocompetent children.

OBJECTIVE: To determine whether recent corticosteroid use was associated with an increased risk of complicated varicella-zoster virus infection in otherwise immunocompetent children. STUDY DESIGN: A case-control study design was used because the outcome of interest, complicated varicella-zoster virus infection, is rare. SETTING: Cases and controls were selected from the population of children aged 2 months to 18 years admitted to two hospitals, between January 1979 and July 1994 in one and between January 1974 and July 1994 in the other, with diagnosis codes that indicated chickenpox. POPULATION: Cases were defined as children with invasive varicella-zoster virus infection or associated invasive bacterial infection. Controls were defined as children with uncomplicated varicella admitted for elective surgery, fracture or burn management, psychiatric or social evaluation, treatment of simple dehydration, or evaluation of fever or rash not yet diagnosed. Exclusions included varicella-zoster virus infection in neonates and immunocompromised children. METHODS: A priori criteria were formulated on the basis of a comprehensive literature review to define complicated varicella-zoster virus infection. Recent corticosteroid exposure was defined as corticosteroid use of any sort within 30 days of onset of the chickenpox rash. Data were abstracted by medical chart review. RESULTS: In total, 167 cases and 134 controls were identified. Only three children (two cases and one control) had a history of recent corticosteroid therapy. Recent corticosteroid exposure was therefore not statistically associated with an increased risk of complicated varicella-zoster virus infection (odds ratio, 1.6; 95% confidence interval, 0.2 to 16.9). No differences between cases and controls were found in sex, history of asthma, or length of hospital stay. The mean age of cases was greater than that of controls (6.0 vs 4.7 years; P<.01). CONCLUSIONS: Recent corticosteroid therapy in otherwise immunocompetent children does not appear to be associated with a statistically increased risk of complicated varicella. A conservative estimate of risk, using the upper limit of the 95% confidence interval, is markedly lower than previously published risk estimates.

Adolescent↗

Increasing irritability with sudden onset of flaccid weakness.

Spontaneous spinal epidural hematoma (SSEH), is a rare and potentially fatal condition that responds favorably to early surgical intervention and should be considered in the differential diagnosis of spinal cord compression. There are few reported cases in children. We present a case of spontaneous spinal epidural hematoma in an 18-month-old child and review the literature.

Hematoma↗

MHC class II alleles and haplotypes in patients with pemphigus vulgaris from India.

Pemphigus vulgaris (PV) is a blistering disease of the skin and mucous membranes characterized by an autoantibody response against a keratinocyte adhesion molecule, desmoglein 3, causing acantholysis and blister formation. We compared high resolution MHC class II alleles and haplotype frequencies (HLA-DRB, DQA1 and DQB1) in 37 patients with PV to 89 haplotypes of normal relatives from New Delhi and Ahmedabad. We found that PV patients had significantly increased frequencies of DRB1*1404 (P < 0.0001), DQA1*0101 (P = 0.001), and DQB1*0503 (P < 0.0001). These associations were due to the increased frequencies of the haplotype HLA-DRB1*1404, DRB3*0202, DQA1*0101, DQB1*0503 in patients compared to control haplotypes (p < 0.0001). Also, patients from Ahmedabad had a significant increase in HLA-DQB1*0302 (p = 0.03). An identical amino acid sequence (Leu-Leu-Glu-Arg-Arg-Arg-Ala-Glu), in positions 67-74 of the beta domain of DRB alleles is restricted to some DR14 alleles. Therefore, there are three possible explanations for class II allele involvement in autoantibody in PV patients with class II haplotypes marked by HLA-DR14. First, the class II alleles could be markers for an unidentified susceptibility gene in linkage disequilibrium with them. Second, the primary association could be with DQB1*0503 and the association with HLA-DR14 alleles would be the result of linkage disequilibrium. Third, the HLA-DRB1 locus susceptibility could involve a specific amino acid sequence in the third hypervariable region shared by several HLA-DR14 alleles.

Alleles↗

Susceptibility of biofilms of Streptococcus sanguis to chlorhexidine gluconate and cetylpyridinium chloride.

Biofilms of Streptococcus sanguis and planktonic cells of the organism were exposed to chlorhexidine gluconate and cetylpyridinium chloride, at concentrations used clinically, and survivors enumerated. S. sanguis exhibited a lower susceptibility to both antiseptics when it comprised a biofilm than when the organism was in the planktonic form. No viable bacteria were detectable after 5 min of exposure of planktonic cells to 0.2% (w/v) chlorhexidine gluconate or 0.05% (w/v) cetylpyridinium chloride, whereas viable bacterial survived in biofilms of S. sanguis even after exposure to these agents for 4 h. Older biofilms (7 days old) had similar susceptibilities to the antiseptics as younger biofilms (4 days old). Chlorhexidine achieved kills corresponding to approximately a 2 log10 reduction in the viable count of biofilms, containing approximately 10(7) colony-forming units after 5 min of incubation, whereas the corresponding kills achieved by cetylpyridinium chloride amounted to approximately a 1 log10 reduction. However, on a molar basis, cetylpyridinium chloride was the more effective of the two antiseptics. Minimum inhibitory concentration determinations showed chlorhexidine gluconate to be more effective against S. sanguis than cetylpyridinium chloride. The results of this study have revealed that the minimum inhibitory concentration is not a reliable predictor of the relative effectiveness of antimicrobial agents against S. sanguis biofilms.

Anti-Infective Agents, Local↗

Procarbazine, lomustine, and vincristine (PCV) chemotherapy for grade III and grade IV oligoastrocytomas.

The authors provided procarbazine, lomustine (CCNU), and vincristine (PCV) chemotherapy to 32 patients whose tumors contained varying mixtures of oligodendroglial and astrocytic cells. Twenty-five patients had oligodendroglioma-astrocytoma (oligoastrocytoma) with a histological Grade of III (19 patients) or IV (six patients); seven had anaplastic oligodendroglioma. The PCV therapy was administered every 6 weeks for a total of at least 124 cycles. The median duration of follow-up review from the start of chemotherapy was 19.3 months. Nineteen patients were treated before receiving radiation therapy and 12 after receiving it (one patient received concurrent radiotherapy and chemotherapy). Grade 3 or 4 hematological toxicity was experienced by nine (31%) of 29 patients. Ten patients had delayed treatment due to treatment-related toxicities (34.5%). Ninety-one percent of the 32 patients responded to the therapy. These included 10 patients with a complete response and 19 with a partial response. The median time to progression was 15.4 months for all patients and 23.2 months for those with Grade III tumors. The median time to progression for patients with Grade III oligoastrocytomas was 13.8 months; for those with Grade IV oligoastrocytoma it was 12.4 months and for those with anaplastic oligodendrogliomas it was 63.4 months (p = 0.0348). These patients survived a median of 49.8 months, 16 months, and 76 or more months, respectively, from the start of chemotherapy (p = 0.0154). The PCV therapy provides durable responses in patients with Grade III or IV oligoastrocytomas.

Adult↗

Diabetes insipidus, acute myelogenous leukemia, and monosomy 7.

Diabetes insipidus together with acute myelogenous leukemia has rarely been seen. Still rarer is the occurrence of monosomy 7 with the two diseases (only six cases reported). A patient who had diabetes insipidus develop before the diagnosis of acute myelogenous leukemia was found at karyotyping to have monosomy 7. Although a specific mechanism whereby monosomy 7 would cause diabetes insipidus has been proposed, some have suggested that monosomy 7 may have its effect by altering cell wall membranes. Others have suggested that acute myelogenous leukemia causes diabetes insipidus by causing infiltrates in the hypothalamus or posterior lobe of the pituitary gland. Magnetic resonance imaging of the patient's brain showed no abnormalities of the hypothalamus or pituitary gland. Lumbar puncture revealed no leukocytes in the cerebrospinal fluid. The authors believe that the cause of diabetes insipidus can be explained in patients with acute myelogenous leukemia by checking for monosomy 7 during karyotyping. Because karyotyping is now more frequently performed in evaluation of patients for chemotherapy or bone marrow transplantation, genetic abnormalities such as monosomy 7 will become increasingly apparent.

Anti-Bacterial Agents↗

Physiologic definitions of obliterative bronchiolitis in heart-lung and double lung transplantation: a comparison of the forced expiratory flow between 25% and 75% of the forced vital capacity and forced expiratory volume in one second.

BACKGROUND AND METHODS: A comparison of the forced expiratory flow between 25% and 75% of the forced vital capacity (FEF25-75) and forced expiratory volume in 1 second (FEV1) was conducted for the detection of obstructive airway disease as an early manifestation of obliterative bronchiolitis. Pulmonary function tests performed on heart-lung and double lung transplant recipients between March 1981 and March 1983 were reviewed. Thirty patients were identified who showed progressive deterioration in pulmonary function after transplantation. Ratios determining proportionate decreases were calculated from measurements of absolute values for the FEF25-75 and FEV1 at the point when the FEF25-75 reached < 70% and < or = 30% of predicted, divided by baseline values obtained before the decline in function. Similar ratios were obtained for FEV1 and FEF25-75 at the point the FEV1 declined > or = 20% from its baseline value. RESULTS: Comparison of the ratios for the FEF25-75 and FEV1 at FEF25-75 values < 70% and < or = 30% of predicted and a similar comparison when the FEV1 declined > or = 20% from baseline showed a greater proportional decrease in FEF25-75 than FEV1 (p < 0.01). With the use of the FEF25-75, declines in airway function were detected earlier. After transplantation a decline in FEF25-75 to < 70% of predicted occurred approximately 112 days before a 20% decline a FEV1. CONCLUSION: The FEF25-75 is more sensitive than the FEV1 for the early detection of obliterative bronchiolitis. A presumptive diagnosis of obliterative bronchiolitis can be made with physiologic criteria, providing infection or acute rejection has been ruled out. When conducting epidemiologic studies or for vital statistics we propose that a decline in FEF25-75 to < 70% be used to define the onset of obliterative bronchiolitis.

Adult↗

Efficacy of combination therapy with insulin and oral hypoglycemic agents in patients with type II diabetes during a 1-year period.

In this retrospective study, the authors assess the efficacy of combined insulin and oral hypoglycemic agents (OHAs) in controlling glycemic levels, as well as lipid levels and insulin requirements, in 48 patients with type II diabetes mellitus during a 1-year period. Thirty-two of these patients had secondary failure to an OHA (group 1). Sixteen patients (group 2) were taking high doses of insulin alone. Overall, 64.6% of all the patients responded to the combination therapy and insulin at 6 months. Response was defined as a decrease in hemoglobin A1c of more than 0.5%. At 12 months, 50% of these patients continued to respond to this regimen. No significant differences were seen in the patients' total cholesterol and triglyceride levels between responders and nonresponders in each group. After 1 year of combination OHA and insulin therapy, 50% of the patients showed a 21.4% reduction in their daily insulin dose.

Administration, Oral↗

Unusual cause of seizure.

INTRODUCTION: This case report of camphor ingestion in a 15-month-old child illustrates the potential toxicity of a common household product. Details of the patient presentation are reported along with a review of the literature. METHODS: Patient information was collected using the records of Poison Control, the Emergency Department, and the Health Records at the Hospital for Sick Children in Toronto, Ontario, Canada. A comprehensive review of the literature was conducted using the MEDLINE database for the time period 1966 to April 1995. DISCUSSION: Oral ingestion of camphor is unusual, given that these products have both unpleasant taste and texture. This patient ingested 70 ml of an over-the-counter medicated ointment containing 4.73% camphor, 2.6% menthol, and 1.2% eucalyptus oil. While the concentration of camphor in this product is low, an estimated 280 mg/kg of camphor was consumed. With significant ingestion of camphor (> 50 mg/kg), neurologic toxicity is common. In this patient, prolonged generalized tonic-clonic seizure activity was noted approximately two hours post single acute ingestion of camphor. This delay in onset of seizure activity is atypical, as seizures have previously been noted to occur in the 90 minutes following ingestion. CONCLUSION: Readily available medicated ointments containing camphor have potential for serious or fatal consequences when ingested by children.

Anti-Infective Agents, Local↗

Hyperinsulinemia and coronary artery disease risk factors in patients with non-insulin-dependent diabetes mellitus and nondiabetics.

A study was undertaken to demonstrate the relationship between known risk factors for coronary artery disease and hyperinsulinemia in both patients without diabetes and patients with non-insulin-dependent diabetes mellitus. Both groups of patients were categorized based on insulin levels in the fasting and 2-hour post glucose challenge state, in relation to the median insulin level for that group. Patients with an insulin level higher than the median value were compared with those with lower insulin levels. Differences in weight; levels of fasting glucose, insulin at 2 hours post glucose challenge, total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very-low-density lipoprotein cholesterol; presence of hypertension; and history of smoking cigarettes-known risk factors for atherosclerosis-were analyzed. An elevated fasting insulin level was found to be strongly associated with a number of atherogenic risk factors in both sets of patients. Weight was the only factor with a consistently positive association with the insulin level in all subgroups. In both groups, the fasting insulin level was associated with more risk factors than the insulin level at 2 hours after administration of 75 g of oral glucose.

Adult↗

[Hepatic encephalopathy induced by flutamide administered for the treatment of prostatic cancer].

A 72-year-old male treated with flutamide for metastatic prostate cancer developed lethargy and confusion. He was noted to be icteric and his liver enzymes were elevated. Within a week of discontinuing the medication, the patient's mental status and liver function returned to normal. Although flutamide-induced near fatal liver dysfunction has been described, progression to encephalopathy is a rare occurrence. Based on a review of the literature, management guidelines for the use of flutamide are suggested.

Adenocarcinoma↗

Squamous cell carcinoma of the head and neck in the elderly.

OBJECTIVE: While squamous cell carcinoma of the head and neck (HNSCC) most commonly affects individuals in the fifth to seventh decades of life, it occasionally arises in older patients. Biologic and epidemiologic factors of HNSCC in elderly patients have been investigated to shed light on the process of neoplastic transformation in that population. DESIGN: The medical records of patients with new onset of HNSCC presenting between 1988 and 1993 were reviewed retrospectively. SETTING: Tertiary-care hospital-based clinic. PATIENTS: Eighty-one individuals who developed HNSCC of the upper aerodigestive tract after their 75th birthday constituted the study group. A control group consisting of 102 patients who developed HNSCC between the ages of 40 and 70 years was also analyzed. MAIN OUTCOME MEASURE: Information about each individual's tobacco and ethanol exposure, family history of cancer, history of second primary cancer, treatment provided, and current disease status were derived from the medical record. The presence or absence of p53 gene mutation was tabulated for a subset of individuals in both the elderly and the middle-aged groups. RESULTS: The elderly patients had a significantly lower degree of alcohol and tobacco exposure, but a significantly higher rate of second primary cancers, especially in sites outside the upper aerodigestive tract. There was no difference in the incidence of cancer in first-degree relatives in the two groups. These findings were interpreted in light of results from our laboratory examining the incidence of p53 gene mutation in a large number of patients with HNSCC. A significantly higher percentage of tumors from the younger group contained a p53 gene mutation. Major surgery was an integral part of the treatment plan for most of the older patient group despite their advanced age. CONCLUSIONS: These findings suggest that HNSCC arising after the seventh decade of life less frequently involves a genetic change commonly found in younger patients. Heavy carcinogen exposure and p53 gene mutations are present less often in elderly individuals, whereas this group appears to be more susceptible to multiple cancers. The precise biologic factors involved in neoplastic transformation in this older population await discovery. Since aggressive therapy can be successfully tolerated by many elderly patients, an individualized approach to treatment is advocated.

Adult↗