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Biomedical subjects

S Malik

Publications and source records attributed to S Malik.

At least 19 recordsLinked to original sources
PubMed2006

Transport properties of CdS nanowire embedded poly(3-hexyl thiophene) nanocomposite.

Electrical transport properties of CdS nanowire embedded regioregular poly(3-hexyl thiophene) (P3HT) nanocomposite are investigated and the results are compared with those of the pure P3HT polymer. Both dc and ac conductivities of P3HT and CdS-P3HT nanocomposites show semiconducting nature and conductivity of CdS-P3HT is much less than that of the pure P3HT conducting polymer. The difference in the electrical behavior is attributed to the formation of nanowires in the CdS-P3HT nanocomposite. The dc conductivity data at high and low temperatures are qualitatively consistent with the optical-photon-assisted hopping and variable-range hopping models, respectively. However, the multiphonon-assisted hopping models of small polarons in nonadiabatic regime, which consider strong interactions with electrons with the optical as well as acoustical phonons, are the best to interpret quantitatively the experimental data in the entire temperature range for both P3HT and CdS-P3HT nanocomposites. We observe that the quantum tunneling model of small polarons is consistent with almost every respect of the loss data of P3HT conducting polymer, while for CdS-P3HT nanocomposite the ac conductivity varies with temperature in a different manner, which is explained in terms of simple quantum tunneling model of electrons in contrast to that of pure P3HT conducting polymer.

Journal Article↗
PubMed2006

Genetic heterogeneity of synpolydactyly: a novel locus SPD3 maps to chromosome 14q11.2-q12.

Syndactyly type II or synpolydactyly (SPD) is the second most frequent syndactyly type and is inherited in an autosomal dominant fashion. The cardinal features of this malformation are the cutaneous or bony fusion of third and fourth fingers, and fourth and fifth toes associated with additional digital elements within the web. It shows incomplete penetrance and high inter- and intrafamilial phenotypic variability. Two loci are known for SPD (MIM 186000, MIM 608180) associated with mutations in HOXD13 and FBLN1, respectively. Here, we report further genetic heterogeneity for SDP. Employing a whole genomic screen, we demonstrate, in a large Pakistani kindred, that the classical phenotype of SPD maps on a new locus at chromosome 14q11.2-q12. The highest LOD score (Z(max) = 4.06) was obtained with microsatellite marker D14S264, and the multipoint LOD score reached a maximum of 5.01. Haplotype analysis revealed that the disease interval is flanked by microsatellite markers D14S283 and D14S1060, encompassing a physical distance of 10.72 Mb. We propose to allocate to this locus the symbol SPD3 (synpolydactyly 3), and to name the loci associated with HOXD13 or FBLN1 mutations SPD1 and SPD2, respectively.

Chromosome Mapping↗
PubMed2005

Variants of the SFTPA1 and SFTPA2 genes and susceptibility to tuberculosis in Ethiopia.

Lungs are the central organ affected and targeted by Mycobacterium tuberculosis and immune processes in the lung are of critical importance in the pathogenesis of tuberculosis. A major lung defense against invading pathogens is provided by surfactant protein A, a multi-chain protein encoded by the SFTPA1 and SFTPA2 genes. Here, we investigated polymorphisms in the SFTPA1 and SFTPA2 genes for association with tuberculosis in 181 Ethiopian families comprising 226 tuberculosis cases. Four polymorphisms, SFTPA1 307A, SFTPA1 776T, SFTPA2 355C, and SFTPA2 751C, were associated with tuberculosis (P=0.00008; P=0.019, P=0.029 and P=0.042, respectively). Additional subgroup analysis in male, female and more severely affected patients provided evidence for SFTPA1/2-covariate interaction. Finally, out of five intragenic haplotypes identified in the SFTPA1 gene and nine identified in the SFTPA2 gene, 1A(3) was most significantly associated with tuberculosis susceptibility (P=0.026). These findings suggest that SFTPA1 and SFTPA2 modify the risk of tuberculosis susceptibility and that this risk is influenced by additional covariates.

Adolescent↗
PubMed2005

A simple method for characterising syndactyly in clinical practice.

Non-syndromic syndactyly is a heterogeneous group of limb malformations involving webbing of fingers and/or toes. There are at least nine non-syndromic types described in the literature. For the clinician and the genetic counsellor not having gathered experience with this malformation, it is rather tedious to identify the correct subtype for the patient's phenotype. We therefore present a protocol for clinical use, which visualises the malformation in a graphical way and thereby simplifies typing. In addition, this protocol provides a simple documentation system for reporting clinical data for new syndactyly families. It might encourage clinicians to report families that are still unclassifed and thus, helping to extend and improve the existing classification system.

Calcium-Binding Proteins↗
PubMed2004

Ultrasonographic evaluation of lower uterine segment thickness in patients of previous cesarean section.

OBJECTIVE: To evaluate by ultrasonography, the lower uterine segment thickness of women with a previous cesarean delivery and determine a critical thickness above which safe vaginal delivery is predictable. METHODS: A prospective observational study of 71 antenatal women with previous cesarean delivery and 50 controls was carried out. Transabdominal and transvaginal ultrasonography were used in both groups to evaluate lower uterine segment thickness. The obstetric outcome in patients with successful vaginal birth and intraoperative findings in women undergoing cesarean delivery were correlated with lower segment thickness. RESULTS: The overall vaginal birth after cesarean section (VBAC) was 46.5% and VBAC success rate was 63.5%, the incidence of dehiscence was 2.82%, and there were no uterine ruptures. There was a 96% correlation between transabdominal ultrasonography with magnification and transvaginal ultrasonography. The critical cutoff value for safe lower segment thickness, derived from the receiver operator characteristic curve, was 2.5 mm. CONCLUSION: Ultrasonographic evaluation permits better assessment of the risk of scar complication intrapartum, and could allow for safer management of delivery.

Adult↗
PubMed2004

Marital status and risk of HIV infection in South Africa.

OBJECTIVE: Available evidence on the relationship between marital status and HIV is contradictory. The objective of this study was to determine HIV prevalence among married people and to identify potential risk factors for HIV infection related to marital status in South Africa. METHODS: A multistage probability sample involving 6 090 male and female respondents, aged 15 years or older was selected. The sample was representative of the South African population by age, race, province and type of living area, e.g. urban formal, urban informal, etc. Oral fluid specimens were collected to determine HIV status. A detailed questionnaire eliciting information on socio-demographic, sex behaviour and biomedical factors was administered through face-to-face interviews from May to September 2002. RESULTS: HIV prevalence among married people was 10.5% compared with 15.7% among unmarried people (p-value < 0.001). The risk of HIV infection did not differ significantly between married and unmarried people (odds ratio (OR) = 0.85, 95% confidence interval (CI): 0.71 - 1.02) when age, sex, socio-economic status, race, type of locality, and diagnosis of a sexually transmitted infection (STI) were included in the logistical regression model. However, the risk of HIV infection remained significantly high among unmarried compared with married people when only sex behaviour factors were controlled for in the model (OR 0.55; 95% CI: 0.47 - 0.66). CONCLUSIONS: The relationship between marital status and HIV is complex. The risk depends on various demographic factors and sex behaviour practices. Increased prevention strategies that take socio-cultural context into account are needed for married people.

Adolescent↗
PubMed2004

Diffusion MR imaging for cerebral abscess.

We report a case of cerebral abscess, which ruptured into the lateral ventricle. The radiological features on conventional MRI, appearance on both diffusion weighted images (DWI) and apparent diffusion coefficient (ADC) maps are described.

Anti-Bacterial Agents↗
PubMed2003

Respiratory disease due to parainfluenza virus in adult leukemia patients.

Reports of human parainfluenza viruses (HPIV) in patients with leukemia have been limited to a few cases or as a portion of general surveys. In order to expand the knowledge of these infections in this patient group, the frequency and clinical course of HPIV infections was determined among 1,787 patients with leukemia treated at The University of Texas M.D. Anderson Cancer Center between July 1994 and December 1997. HPIV was isolated from 47 (6.2%) of the 770 patients who were cultured for respiratory viruses. HPIV type 3 accounted for 39 of the 47 HPIV infections. Twenty-six patients developed pneumonia, and the associated mortality was 27%. Multivariate analysis revealed that a low absolute lymphocyte count and pneumonia were associated with increased mortality. Concurrent respiratory and other infections were associated with an increased frequency of pneumonia. Only five patients with pneumonia received antiviral therapy and four of them survived the infection. HPIV infection in leukemic patients is frequently associated with pneumonia and the mortality rate from pneumonia is substantial among lymphopenic patients.

Adolescent↗
PubMed2003

An evaluation of topical and local anesthesia in phacoemulsification.

OBJECTIVE: To assess the comparative efficacy of topical and local anesthesia in phacoemulsification. MATERIAL AND METHODS: The medical records of 186 men and women between the ages of 45-85 years, who underwent elective cataract surgery by phacoemulsification technique, under the care of one surgeon, over a period of one year, from March 1999-March 2000 were reviewed. RESULTS: Of 186 patients who underwent small incision, self-healing phacoemulsification cataract surgery, 124 received topical and 62 local anesthesia. The most common cataract types were nuclear sclerosis. The duration of surgery with topical anesthesia was shorter. Sutures and eye padding were more frequently applied for procedures done under local anesthesia. Uncorrected visual acuity in the first post-op week was between 20/20-20/50 for 53.6% of the cases done under topical compared to 30.9% in local anesthesia. A similar trend was noted in the visual acuity one month post operatively. CONCLUSION: The uncorrected visual acuity improves faster and the duration of surgery is shorter when topical anesthesia is used.

Administration, Topical↗
PubMed2002

Adult onset pigmentary orthochromatic leukodystrophy with ovarian dysgenesis.

Pigmentary type of orthochromatic leukodystrophy (POLD) is an adult-onset leukodystrophy, characterized pathologically by the presence of glial and microglial cytoplasmic pigment inclusions. The complete phenotype, genotype and pathogenetic mechanisms in POLD have not been elucidated. We followed for 18 years a woman with autopsy-proven POLD, who presented with 'frontal' dementia and spasticity. Her further course was marked by progressive mutism, apraxia and seizures. Her sister had died of the same disease after a much more rapidly progressing course. These sisters had primary infertility with pathologic evidence of streak ovaries. Diagnosis was confirmed in both cases by post-mortem examination. POLD is a rare cause of adult-onset leukodystrophy presenting with dementia. Ovarian dysgenesis is extremely rare in the absence of demonstrable chromosomal abnormalities and extends the clinical spectrum of POLD.

Adult↗
PubMed2002

Lung deposition of salbutamol in healthy human subjects from the MAGhaler dry powder inhaler.

The MAGhaler (Mundipharma GmbH) is a multidose dry powder inhaler (DPI) containing a novel formulation of drug and lactose compacted by an isostatic pressing technique (GGU GmbH). On actuation, a precise dose is metered from a compacted ring-shaped drug tablet. In this study, the lung deposition of salbutamol from this device has been assessed. Ten healthy non-smoking subjects completed a two-way cross-over study assessing the pulmonary deposition of salbutamol (200 microg) from the MAGhaler at high (60 l/min) and low (30 l/min) peak inhaled flow rates (PIFRs), representing maximal and sub-maximal inspiratory efforts. The formulation was radiolabelled with 99mTc, and lung and oropharyngeal depositions were quantified by gamma scintigraphyThe mean (SD)% ofthe delivered dose deposited in the lungs was 26.4 (4.3)% at 60 l/min and 21.1 (5.1)% at 30 l/min (P < 0.05), corresponding to mean lung depositions of 52.8 and 42.2 microg salbutamol, respectively. The distribution of drug within different lung regions did not vary significantly with inhaled flow rate. The data provided proof of concept for the novel inhaler device and the innovative drug formulation. In comparison with previous deposition data obtained with other DPIs, the lung deposition was relatively high, relatively reproducible (coefficient of variation 16% at 60 l/min) and relatively insensitive to the change in peak inhaled flow rate.

Adult↗
PubMed2002

Comparative analysis of knowledge, attitudes and perceptions about induced abortions among medical and non-medical students of Karachi.

OBJECTIVE: To determine the knowledge, attitudes and perceptions regarding induced abortions among university students of Karachi and compare these aspects among medical and non-medical students. STUDY DESIGN: Cross sectional opinion survey. METHODS: The study is a cross sectional opinion survey of medical and non-medical students from four educational institutions of Karachi using a pretested questionnaire. RESULTS: Of the 381 students interviewed, 201 were medical and 180 were non-medical. More medical students were aware of the correct definition of induced abortion. An encouraging finding was the awareness of our study population about the only legally acceptable circumstance for induced abortion in Pakistan, that is, if conceptus is a risk to maternal health (p<0.001). More medical students cited complications that were technical like uterine perforation (p<0.001), cervical trauma (p<0.001), DIC (p<0.001), and sepsis (p<0.001). More medical students thought induced abortion to be a health issue (p=0.001) as compared to non-medical students. Most of the medical students felt the need to modify Pakistan's law regarding abortion (p=0.008) especially for fetal anomalies (13.9%) and rape (7%). CONCLUSION: Though medical students were more knowledgeable about induced abortions as compared to the non-medical population, there is a need to improve awareness regarding induced and unsafe abortions and their consequences.

Abortion, Induced↗
PubMed2001

Dysregulation of integrin-linked kinase (ILK) signaling in colonic polyposis.

Mutation of the adenomatous polyposis coli (APC) gene and the subsequent dysregulation of beta-catenin are well-documented abnormalities in familial adenomatous polyposis (FAP), as well as sporadic polyposis. Intriguingly, overexpression of the integrin-linked kinase (ILK) has been shown to modulate beta-catenin subcellular localization and function. However, the significance of this finding for human carcinogenesis remains unclear. Here, we report the increased biochemical activity and expression of ILK protein in polyps from FAP patients. Furthermore, dramatic increases in ILK immunoreactivity were observed in all abnormal crypts from sporadic polyps, when compared with the normal appearing crypts within the same resected specimens. As sulindac and aspirin are the two most important therapeutic/chemopreventative agents demonstrated in colorectal carcinogenesis, in both humans and animals, further investigation revealed that these non-steroidal anti-inflammatory drugs (NSAIDs) target ILK and ILK-mediated events in vivo. These include inhibition of, both the biochemical activation of ILK, inhibition of serine 9 GSK3beta phosphorylation and the enhancement of TCF-4 transcriptional activity. In conclusion, ILK protein hyperexpression appears to be an early event in colonic polyposis. Additionally, ILK signaling is shown to undergo modulation by sulindac (and aspirin) for the first time, indicating that it is likely to be one of the targets affected by these agents in vivo.

Adenomatous Polyposis Coli↗
PubMed2001

Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study.

Researchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras in-colorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes' C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes' B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer.

Adolescent↗
PubMed2001

Narcolepsy associated with other central nervous system disorders.

The authors identified patients with the coexistence of narcolepsy and another CNS disorder seen between 1975 and 1998 at their institution. Eighteen patients were identified, nine with narcolepsy commencing within 1 year before or after the other disorder. Seven patients (39%) had hypothalamic-pituitary syndromes. When they occur together, narcolepsy and other CNS disorders frequently emerge at about the same time, suggesting a causative relationship. Hypothalamic-pituitary pathology was the most common association.

Brain↗