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Biomedical subjects

S Khan

Publications and source records attributed to S Khan.

At least 37 records · Page 2Linked to original sources
PubMed2006

Immunization of pigs against chicken gonadotropin-releasing hormone-II and lamprey gonadotropin-releasing hormone-III: effects on gonadotropin secretion and testicular function.

The objective of this experiment was to evaluate the effects of active immunization against 2 GnRH isoforms on gonadotropin secretion and testicular function in pigs. Synthetic chicken (c) GnRH-II and lamprey (l) GnRH-III peptides, with the common pGlu-His-Trp-Ser sequence at the N-terminal omitted, were conjugated to BSA. Forty-eight male piglets were randomly assigned to 1 of 4 treatments. Pigs on treatment 1 were actively immunized against cGnRH-II, whereas pigs on treatment 2 were actively immunized against lGnRH-III. Control pigs on treatment 3 were actively immunized against the carrier protein (BSA), and pigs on treatment 4 were castrated and actively immunized against BSA. The BSA conjugate was emulsified in Freund's Incomplete Adjuvant and diethylaminoethyldextran. Primary immunization was given at 13 wk of age (WOA) with booster immunizations given at 16 and 19 WOA. Body weight and plasma samples were collected weekly beginning at 11 WOA. Treatments did not affect BW during the experimental period. Antibody titers were increased in animals immunized against cGnRH-II and lGnRH-III (P < 0.001). Cross-reactivity of the antibodies to mammalian GnRH or between cGnRH-II and lGnRH-III was minimal. Concentrations of testosterone were maximal in control boars (treatment 3) and minimal in control barrows (treatment 4) and immunized pigs (treatment x week; P < 0.01). Immunized animals had concentrations of LH (P < 0.001) and FSH (treatment x week; P < 0.03) that were less than control barrows and similar to control boars. At the end of the experiment, intact (noncastrated) pigs were exsanguinated. Testes were removed immediately; Leydig cells were isolated and treated with 0, 1, or 10 ng/mL of LH. There was an LH x GnRH treatment effect on testosterone concentrations (P < 0.03), indicating that Leydig cells were sensitive to the immunization protocol and doses of LH. Taken together, these data suggest that immunization against GnRH isoforms decreased gonadotropin secretion compared with control barrows. Additionally, immunization against cGnRH-II and lGnRH-III reduced the ability of Leydig cells to respond to LH challenges.

Animals↗
PubMed2006

Detection of biofilm formation among the clinical isolates of Staphylococci: an evaluation of three different screening methods.

PURPOSE: The purpose of this study was to evaluate three methods for detection of biofilm formation in staphylococci. METHODS: For detection of biofilm formation, 152 clinical isolates of Staphylococcus spp. were screened by tissue culture plate (TCP), Tube method (TM) and Congo red agar (CRA) method. RESULTS: Of the 152 Staphylococcus spp. 88(57.8%) displayed a biofilm-positive phenotype under the optimized conditions in the TCP method and strains were further classified as high 22 (14.47 %) and moderate 60 (39.4 %) while in 70 (46.0 %) isolates weak or no biofilm was detected. Though TM correlated well with the TCP test for 18 (11.8 %) strongly biofilm producing strains, weak producers were difficult to discriminate from biofilm negative isolates. Screening on CRA does not correlate well with either of the two methods for detecting biofilm formation in staphylococci. CONCLUSION: The TCP method was found to be most sensitive, accurate and reproducible screening method for detection of biofilm formation by staphylococci and has the advantage of being a quantitative model to study the adherence of staphylococci on biomedical devices.

Agar↗
PubMed2006

Antifungal susceptibility testing method for resource constrained laboratories.

PURPOSE: In resource-constrained laboratories of developing countries determination of antifungal susceptibility testing by NCCLS/CLSI method is not always feasible. We describe herein a simple yet comparable method for antifungal susceptibility testing. METHODS: Reference MICs of 72 fungal isolates including two quality control strains were determined by NCCLS/CLSI methods against fluconazole, itraconazole, voriconazole, amphotericin B and cancidas. Dermatophytes were also tested against terbinafine. Subsequently, on selection of optimum conditions, MIC was determined for all the fungal isolates by semisolid antifungal agar susceptibility method in Brain heart infusion broth supplemented with 0.5% agar (BHIA) without oil overlay and results were compared with those obtained by reference NCCLS/CLSI methods. RESULTS: Comparable results were obtained by NCCLS/CLSI and semisolid agar susceptibility (SAAS) methods against quality control strains. MICs for 72 isolates did not differ by more than one dilution for all drugs by SAAS. CONCLUSIONS: SAAS using BHIA without oil overlay provides a simple and reproducible method for obtaining MICs against yeast, filamentous fungi and dermatophytes in resource-constrained laboratories.

Antifungal Agents↗
PubMed2005

A multi-objective optimisation approach to water management.

The management of river basins is complex especially when decisions about environmental flows are considered in addition to those concerning urban and agricultural water demand. The solution to these complex decision problems requires the use of mathematical techniques that are formulated to take into account conflicting objectives. Many optimization models exist for water management systems but there is a knowledge gap in linking bio-economic objectives with the optimum use of all water resources under conflicting demands. The efficient operation and management of a network of nodes comprising storages, canals, river reaches and irrigation districts under environmental flow constraints is challenging. Minimization of risks associated with agricultural production requires accounting for uncertainty involved with climate, environmental policy and markets. Markets and economic criteria determine what crops farmers would like to grow with subsequent effect on water resources and the environment. Due to conflicts between multiple goal requirements and the competing water demands of different sectors, a multi-criteria decision-making (MCDM) framework was developed to analyze production targets under physical, biological, economic and environmental constraints. This approach is described by analyzing the conflicts that may arise between profitability, variable costs of production and pumping of groundwater for a hypothetical irrigation area.

Agriculture↗
PubMed2005

Atomic force microscopy measurement of the elastic properties of the kidney epithelial cells.

Direct interaction force measurements using atomic force microscopy (AFM) were carried out between a silicon nitride tip and renal epithelial cells (Madin-Darby Canine Kidney-MDCK and proximal tubular epithelial cells derived from pig kidneys, LLC-PK1). The approaching (extending) portion of the force/distance curves is considered, and repulsive forces in the long range of 2-3 microm were seen in both MDCK as well as LLC-PK1 cells growing under normal conditions. The repulsive force in the shorter distance range of 50-200 nm was also observed, when cells were damaged exposing the underlying basal membrane. LLC-PK1 cells were more prone to damage than the MDCK cells, hence short-range forces were common in the former and long-range forces in the latter cells. The functional dependence of repulsive force on the indentation depth changes, at small indentation depth the force increases linearly, while at larger indentations the force is a quadratic function of the distance, which is attributed to the elasticity of the membrane and the solid-like response of cells, respectively. The oxalate treatment of cells for 2-4 h gives rise to an increase in the elastic modulus of the cells.

Animals↗
PubMed2005

Life-style modification in peripheral arterial disease.

OBJECTIVE: To review the published evidence supporting the use of life-style modification in peripheral arterial disease (PAD). DESIGN: A systematic search of the medical literature was performed for relevant studies. MATERIALS: The publications obtained were then searched for randomised clinical trials which reported end-points of mortality or major cardiovascular event rates with various life-style modifications. RESULTS: Only one randomised controlled trial was found reporting relevant end-points. Other trials were of other end-points such as walking distance or biochemical markers. CONCLUSIONS: There is a lack of randomised controlled data proving the benefit of life-style modification in improving mortality and reducing cardiovascular events in patients with PAD. Despite this there is sufficient evidence to recommend some life-style modification as part of the overall approach to risk reduction in these patients. There is compelling evidence to support smoking cessation, increased exercise and improved diet.

Arterial Occlusive Diseases↗
PubMed2005

Differential alteration of stem and other cell populations in ducts and lobules of TGFalpha and c-Myc transgenic mouse mammary epithelium.

Genes associated with proliferation are active in stem and progenitor cells, and their over-expression can promote cancer. Two such genes, c-Myc and TGFalpha, promote morphologically dissimilar mammary tumors in transgenic mice. We investigated whether their over-expression affects population size and cell cycle activity in stem and other cell populations in non-neoplastic mammary epithelia. Results indicated that both cell population and cell cycle regulation are cell type- and microenvironment-specific. To create a tool for identifying and categorizing the five cellular phenotypes by light microscopy, we adapted previously established ultrastructural criteria. Using nulliparous MMTV-c-myc or MT-tgfalpha mice, we determined and compared the relative sizes the putative stem, progenitor and differentiated cell populations. PCNA staining was used to compare the portion of each cell population in the cell cycle. Cell population sizes were analyzed relative to: (1) their location in ducts versus lobules (microenvironment), (2) genotype, and (3) cell type. Population sizes differed significantly by genotype, depending on microenvironment (p=0.0008), by genotype, depending on cell type (p<0.0001), and by microenvironment, depending on cell type (p=0.03). The number of cycling cells was also affected by all three factors, confirming that the interplay of cell type, gene expression and three-dimensional organization are very important in tissue morphogenesis and function. We describe a structure in mammary epithelium consistent with that of a stem cell niche, and show that it is altered in MMTV-c-myc and likely altered in MT TGFalpha transgenic epithelia.

Animals↗
PubMed2005

A comparative study of fine needle aspiration cytology versus non-aspiration technique in thyroid lesions.

The present study was done to explore the diagnostic yield by the non-aspiration technique as compared with fine needle aspiration cytology (FNAC) of lesions in the thyroid gland. This method of non-aspiration fine needle cytology, which utilizes no active suction or aspiration, was performed on 150 patients presenting with enlargement of the thyroid gland. Smears were then cytologically assessed as unsuitable, diagnostically adequate or diagnostically superior, without knowledge of the sampling method employed. Diagnostically superior specimens were obtained significantly more frequently by the non-aspiration technique in 136 benign lesions and 14 neoplasms. Thus, the non-aspiration technique combined with FNAC can result in obtaining good quality cellular material in thyroid lesions.

Biopsy, Fine-Needle↗
PubMed2005

Evaluation of methods for AmpC beta-lactamase in gram negative clinical isolates from tertiary care hospitals.

The purpose of this study was to simultaneously screen for Extended-spectrum beta-lactamases (ESBL) and AmpC beta-lactamases in gram negative clinical isolates from four tertiary care hospitals and further to compare two detection methods three-dimensional extraction method and AmpC disk test for AmpC beta-lactamases. A total of 272 isolates were screened for ESBL and AmpC beta-lactamase by modified double disk approximation method (MDDM). Synergy observed between disks of ceftazidime/cefotaxime and clavulanate were considered as ESBL producer. Isolates showing reduced susceptibility to either of the test drugs (ceftazidime or cefotaxime) and cefoxitin were considered as presumptive AmpC producers and further confirmed by three-dimensional extraction method and AmpC disk test. A total of 173 (64%) of the isolates were found to be ESBL positive and 61 (23%) showed resistant to cefoxitin. ESBL was detected in 80 (62%) isolates of E. coli and 71 (73%) of Klebsiella spp. The occurrence of AmpC beta-lactamases was found to be 8% (22) of the total isolates and the two detection methods for AmpC beta-lactamase showed concordant results. Screening for ESBL and AmpC can be simultaneously done by MDDM method and confirmation for AmpC beta-lactamase should be carried out routinely in tertiary care hospitals by AmpC disk test, as it is a simple and rapid procedure.

Anti-Bacterial Agents↗
PubMed2005

Tuberculosis education in an endemic setting: application of participatory methods to video development in The Gambia.

OBJECTIVE: To produce an educational video for tuberculosis (TB) awareness in The Gambia using participatory methods and integrated formative evaluation. METHODS: A steering group was formed of key people working in TB research, health education, the health service and the media. They developed a script and commissioned local production of the video in three local languages and English. A formative participatory evaluation of the project was conducted using document review, attendance at rehearsals and semi-structured interviews. A pilot version of the video was evaluated through focus groups in Banjul and remote villages. Data were analysed using a general inductive approach. RESULTS: Five major themes emerged from evaluation of the project participatory process: collaboration, knowledge sharing, networking, ownership and a common desire to sustain the project goals for video dissemination. The video was well received and described as informative, entertaining and professional. Audiences were able to identify the key messages, prevailing attitudes about TB were challenged, and many participants expressed a desire to act on their new knowledge. CONCLUSION: A participatory approach to the development of a video in The Gambia proved to be empowering to local participants and led to the production of a resource well received by Gambian people.

Community Participation↗
PubMed2004

Prevalence of right ventricular myocardial infarction in patients with acute inferior wall myocardial infarction.

The objective was to evaluate the prevalence of right ventricular myocardial infarction (RVMI) in patients with acute inferior wall myocardial infarction (IWMI) admitted to the National Institute of Cardiovascular Diseases, Karachi, Pakistan. Between August 2000 and May 2001, a total of 100 patients with acute IWMI were enrolled. History of all patients was taken, and thorough clinical examination was performed to asses the presence of signs of right ventricular infarction. Standard 12-lead electrocardiogram was recorded immediately on arrival of patients along with right precordial leads. All patients were considered for thrombolytic therapy in the absence of any contraindication and were managed with standard treatment strategies. Complications arising during the course of admission were recorded and compared between the two groups. There were 86 (86%) males and 14 (14%) females. Mean age was 56.3 +/- 13.13 years (range 33-83 years). The prevalence of RVMI in IWMI was 34%. Smoking and diabetes were more prevalent in RVMI group, while hypertension and family history of ischemic heart disease were more common in isolated IWMI. Ninety per cent of patients received thrombolytic therapy. In-hospital mortality (23.5%) was higher in RVMI group than isolated IWMI (18.1%). Other major complications were also higher in RVMI group than isolated IWMI. Right ventricular infarction was found in approximately one-third of IWMI. Right ventricular infarction was associated with considerable morbidity and mortality, and its presence defines a higher risk subgroup of patients with inferior wall left ventricular infarction.

Adult↗
PubMed2004

A systematic review of hand-assisted laparoscopic live donor nephrectomy.

We provide a systematic review of hand-assisted laparoscopic live donor nephrectomy (HALDN), a relatively new procedure. Medline search of HALDN between 1995 and 2002 was conducted. Published studies were scored by two independent assessors using a modified form of 11 generic questions. All questions required one of three responses: 0--criterion not reported, 1--criterion reported but inadequate, 2--criterion reported and adequate. The studies were placed according to their scores in category A (score 20-22), category B (17-19) and category C (16 or less). Higher scores indicate better quality of studies. Where possible, statistical analysis of comparative data was performed. Most reports of HALDN are expert series, some comparative and a few prospective. There was good correlation between the assessors (r = 0.91), and of the seven published series on HALDN, two fell into category B and five into category C. At present, there is only one published randomised-controlled trial of HALDN vs. open donor nephrectomy; this is the only such trial in laparoscopic urology. HALDN allows kidneys to be harvested with short operating and warm ischaemia times and fewer ureteric complications. HALDN is a relatively new and effective technique, designed to make kidney donation more attractive and minimally invasive without affecting recipient outcomes. More prospective data of this technique is needed, and wide variation in reported outcome parameters need to be standardised to allow meaningful comparison.

Humans↗
PubMed2004

Does amygdaloid corticotropin-releasing hormone (CRH) mediate anxiety-like behaviors? Dissociation of anxiogenic effects and CRH release.

The brain corticotropin-releasing hormone (CRH) circuits are activated by stressful stimuli, contributing to behavioral and emotional responses. The present study assessed anxiety-like responses and in vivo neurochemical alterations at the central nucleus of the amygdala (CeA) evoked by exposure to an unfamiliar (anxiogenic) environment. Also, the impact of anxiolytic treatments and those that affect CRH were assessed in this paradigm. Novel environment (new cage) markedly suppressed ingestion of a palatable snack. This effect was dose-dependently antagonized by diazepam and was utilized as an index of anxiety in the rodent. Although exposure to a novel environment also stimulated the in vivo release of CRH and glutamate at the CeA, various CRH antagonists (e.g. alphah-CRH, Calpha-MeCRH, CP-154,526, antisauvagine-30, preproTRH178-199) did not attenuate the stressor-elicited behavioral suppression, although Calpha-MeCRH was found to attenuate the freezing response elicited by contextual stimuli that were associated with previously administered footshock. Moreover, central infusion of CRH failed to suppress snack consumption in the home cage. Although diazepam had potent anxiolytic effects in this paradigm, this treatment did not prevent the stressor-associated release of CRH and glutamate at the CeA. Thus, while neural circuits involving CRH and/or glutamatergic receptors at the CeA may be activated by an unfamiliar environment, the data challenge the view that activation of these receptors is necessary for the expression of anxiety-like behavioral responses. Rather than provoking anxiety, these systems might serve to draw attention to events or cues of biological significance, including those posing a threat to survival.

Amygdala↗
PubMed2004

Communicating information on cardiopulmonary resuscitation to hospitalised patients.

AIM: The primary aim of the study was to evaluate two different methods of communicating information on cardiopulmonary resuscitation (CPR) to patients admitted to general medical and elderly care wards. The information was either in the form of a detailed information leaflet (appendix I) or a summary document (appendix II). The study examined the willingness of patients in seeking detailed information on cardiopulmonary issues. SETTING: The study was conducted over three months on a general medical ward and an acute elderly care ward in two district general hospitals. METHODS: A detailed information leaflet on CPR was provided to the nursing staff on the wards. An A4 summary document summarising the CPR decision making process and basic information on cardiopulmonary issues was placed in a folder at the foot of each bed on the elderly care ward. On the general medical ward it was displayed prominently over the head of all beds. RESULTS: Out of the 274 patients admitted to the general medical ward only two requests were received for the detailed information leaflet. On the elderly care ward there were 182 admissions but no patients or their relatives requested the leaflet. CONCLUSIONS: Availability of basic information on cardiopulmonary resuscitation to all patients is practical and does not lead to unnecessary distress or offence to patients or their carers. It makes the decision making process more transparent. Detailed information leaflets are of value for a minority of hospitalised patients.

Cardiopulmonary Resuscitation↗
PubMed2003

Determination by liquid chromatography with fluorescence detection of total 7-ethyl-10-hydroxy-camptothecin (SN-38) in beagle dog plasma after intravenous administration of liposome-based SN-38 (LE-SN38).

An HPLC- fluorescence method to quantitate total 7-ethyl-10-hydroxy-camptothecin (SN-38) in beagle dog plasma spiked with liposome based formulation of SN-38 (LE-SN38) and using camptothecin (CPT) as the internal standard (I.S.) was developed and validated to support pharmacokinetics/toxicokinetics studies. Sample preparation was done by protein precipitation using acetonitrile with 0.5% acetic acid. The supernatant was evaporated, and reconstituted in acetonitrile-20 mM ammonium acetate, pH 3.5 (20:80, v/v). When injected onto a Zorbax SB-C(18) HPLC column SN-38 as well as I.S. were detected by fluorescence using an excitation at 368 nm and emission at 515 nm. The SN-38 concentrations in samples were calculated from a standard curve of peak area ratios of SN-38 to the I.S. using weighted linear regression. The sensitivity limit for SN-38 was 1.00 ng/ml in beagle dog plasma with a precision (expressed as relative standard deviation) of 12.4% and an accuracy (expressed as analytical recovery) of 104%. The assay was linear within the standard curve range of 1-750 ng/ml. Acceptable precision and accuracy were also obtained for concentrations over the balance of the standard curve range from between-run and within-run calculations.

Animals↗