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Biomedical subjects

S I Ahmed

Publications and source records attributed to S I Ahmed.

At least 19 recordsLinked to original sources
PubMed2005

Mobile in vivo camera robots provide sole visual feedback for abdominal exploration and cholecystectomy.

The use of small incisions in laparoscopy reduces patient trauma, but also limits the surgeon's ability to view and touch the surgical environment directly. These limitations generally restrict the application of laparoscopy to procedures less complex than those performed during open surgery. Although current robot-assisted laparoscopy improves the surgeon's ability to manipulate and visualize the target organs, the instruments and cameras remain fundamentally constrained by the entry incisions. This limits tool tip orientation and optimal camera placement. The current work focuses on developing a new miniature mobile in vivo adjustable-focus camera robot to provide sole visual feedback to surgeons during laparoscopic surgery. A miniature mobile camera robot was inserted through a trocar into the insufflated abdominal cavity of an anesthetized pig. The mobile robot allowed the surgeon to explore the abdominal cavity remotely and view trocar and tool insertion and placement without entry incision constraints. The surgeon then performed a cholecystectomy using the robot camera alone for visual feedback. This successful trial has demonstrated that miniature in vivo mobile robots can provide surgeons with sufficient visual feedback to perform common procedures while reducing patient trauma.

Abdomen↗
PubMed2005

Homocysteine level in patients with established transmural myocardial infarction.

OBJECTIVE: To evaluate the levels of serum total homocysteine in patients suffering from established transmural myocardial infarction and normal healthy subjects of local population. DESIGN: A case control study. PLACE AND DURATION OF STUDY: The present study was carried out at Dr. Hafiz Muhammad Ilyas (HMI) Institute of Pharmacology and Herbal Sciences in collaboration with National Institute of Cardiovascular Diseases, Karachi, from June 2001 to December 2001. PATIENTS AND METHODS: Eighty-four persons were included in a case control study. Sixty-three patients were cases suffering from transmural myocardial infarction of anterior wall and 21 normal healthy subjects were controls having no history of IHD ever before. Fasting venous serum was analyzed for total homocysteine using fluorescence polarization immunoassay (FPIA) while lipid parameters and plasma glucose were estimated by enzymatic colorimetric method. RESULTS: Mean serum total homocysteine and low density lipoprotein cholesterol (LDL-C) levels [19.43+/-2.46 umol/L, 124.97+/-45.31 mg/dl respectively] were found to be significantly higher in cases as compared to controls. The mean serum High density lipoprotein cholesterol (HDL-C) [27.57+/-15.31 mg/dl] was found to be significantly lower as compared to control. Mean serum glucose, total cholesterol and serum triacylglycerol [84.32+/-2.46 mg/dl, 174.35+/-27.08 mg/dl and 148.49+/-43.12 mg/dl respectively] were higher in patients as compared to control but difference was insignificant statistically. CONCLUSION: Significantly high levels of total homocysteine along with high levels of LDL-C and low levels of HDL-C appear to be the factors responsible for the increase risk of coronary artery disease in our local population.

Adult↗
PubMed2004

Vascular endothelial growth factor (VEGF) inhibition by small molecules.

Angiogenesis is essential for primary tumours to grow and metastasise, and is driven by the production of positive angiogenic factors. The Vascular Endothelial Growth Factor (VEGF) family is central to the process of angiogenesis and comprises 5 molecules designated A, B, C, D and E. VEGF is overexpressed in several solid malignancies. The actions of VEGF are mediated through receptors possessing tyrosine kinase activity: VEGFR-1 (Flt-1), VEGFR-2 (Kdr/Flk-1) and VEGFR-3 (Flt-4). Anti-VEGF strategies include the use of antibodies to VEGF or its receptors, the use of ribozymes to decrease receptor expression, and the use of inhibitors of tyrosine kinase to reduce receptor activation and downstream signalling. The focus of this review is small molecule inhibitors of VEGF receptors which target their intrinsic tyrosine kinase activity. The clinical development of the following agents is discussed: SU5416, SU11248, SU6668, PTK/ZK, ZD6474.

Angiogenesis Inhibitors↗
PubMed2001

Use of RT-PCR to detect co-expression of neuropeptides and their receptors in lung cancer.

Small-cell lung cancer (SCLC) synthesises a wide range of neuropeptides and their corresponding receptors. Together, these can form autocrine growth loops. Non-small-cell lung cancer (NSCLC) does not generally share this neuroendocrine phenotype. In this study, we tested the hypothesis that multiple neuropeptides and their receptors are co-expressed in SCLC, constituting potential autocrine loops. Expression of mRNA for arginine vasopressin, gastrin, cholecystokinin, gastrin-releasing peptide, endothelin and neurotensin, together with their cognate receptors, was evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) in a panel of human lung cancer cell lines. We have assessed those neuropeptides and neuropeptide receptors that could be used as potential early markers to detect lung cancer cells both as micrometastases in blood and within dysplasia in bronchial biopsies. We establish that although no cell line expressed all neuropeptides, co-expression of neuropeptides and their receptors is common in SCLC but not in NSCLC. We conclude that mRNA for the neuropeptides gastrin-releasing peptide and arginine vasopressin and the cholecystokinin receptor B were most SCLC-specific and RT-PCR for these markers could be used to distinguish between SCLC and NSCLC.

Carcinoma, Non-Small-Cell Lung↗
PubMed2001

Modified insitu vaginal wall sling in stress incontinence.

To assess the efficacy of a modified technique in stress incontinence, that is vaginal wall sling reinforced with two layers of vaginal wall sutured inferiorly. 27 patients with Type II incontinence, 4 with Type III and 14 with mixed type who completed two years follow up were included into the study. Cure, improvement and failure rates were 84.4%, 8.9% and 6.7% respectively. Temporary retention is observed in 30 of the patients, vaginal stenosis and pelvic pain in 1 and suture granuloma in 5 of the patients. Reinforced insitu vaginal wall sling which gives additional support to urethral hammock inferiorly offers a better solution to both types of stress incontinence.

Adult↗
PubMed2001

Importance of the C-terminal phenylalanine of gastrin for binding to the human CCK(2) receptor.

The importance of the C-terminal Phe of gastrin and structural requirements at position 17 for binding to the human CCK2 receptor were assessed using analogs of [Leu15]G(11-17). The following peptides were synthesized, Ac[Leu15]G(11-17), Ac[Leu15]G(11-16)NH2, [Leu15]G(11-17), [Leu15,Ala17]G(11-17), [Leu15,Abu17]G(11-17), [Leu15,Val17]G(11-17), [Leu15,Leu17]G(11-17), [Leu15,Cha17]G(11-17), [Leu15,Trp17]G(11-17), [Leu15,Tic17]G(11-17), [Leu15, d-Phe17]G(11-17) and [Leu15,p-X-Phe17]G(11-17), where X = F, Cl, Br, I, OH, CH3, NH2 and NO2. Competition binding experiments with [3H]CCK-8 were performed using human CCK2 receptors stably expressed in CHO cells. Phe17 was shown to be important for binding. A hydrophobic side-chain larger than Leu is required at position 17 but aromaticity does not appear to be essential. Constraint of the aromatic side-chain either in the g+ or g- conformation, as in the case of Tic, results in a significant decrease in affinity. In addition, the peptide conformation induced by incorporation of d-Phe decreases binding. The size and electron withdrawing/donating properties of the para substituent are not important for interaction with the receptor. The current study shows that the use of des-Phe analogs of gastrin is not a viable strategy for development of antagonists for the human CCK2 receptor.

Amino Acid Motifs↗
PubMed2001

Knowledge, attitudes and practices of general practitioners in Karachi District Central about tetanus immunization in adults.

OBJECTIVE: To assess the knowledge, attitude and practices of general practitioners regarding tetanus immunization in adults. SETTING: The study was conducted in District Central, Karachi. STUDY DESIGN: This was a Knowledge, Attitude and practices (KAP) survey. METHODS: From a list of 1050 general practitioners (GPs), 100 were selected through simple random sampling and interviewed through a written questionnaire. RESULTS: Only 25% general practitioners had adequate knowledge about pre-exposure and 13% both pre- and post-exposure tetanus immunization. All were ready to participate in any program to update their knowledge. Ninety seven percent were practicing only post-exposure immunization. In unimmunized patients with history of road side/street injury, 55% started tetanus immunization with tetanus toxoid (TT) only, 43% with Anti Tetanus Serum/Tetanus Immunoglobin (ATS/TIG) and only 2% with both TT and ATS/TIG. Only 13% GPs advised their patients to complete three doses of tetanus toxoid after initial contact. CONCLUSION: As majority of GPs had poor knowledge and incorrect practices so interventions like seminars and display of immunization protocols in the clinics are recommended.

Female↗
PubMed2000

The rate of urgency symptoms in women with stress urinary incontinence and nomogram based bladder outlet obstruction.

We reviewed the charts of 132 women 30 of whom were chosen as obstructed, 30 equivocal and 72 as unobstructed by automatically given nomograms in the urodynamic evaluation for stress incontinence. The rates of urgency symptoms in nomogram based obstructed, equivocal and unobstructed cases of stress incontinence were found in 30%, 23.3% and 12.5% respectively. More urgency symptoms were observed in women with stress incontinence and nomogram based bladder outlet obstruction than in equivocal and unobstructed cases.

Adult↗
PubMed2000

Deep dorsal vein arterialization in pure cavernoocclusive dysfunction.

PURPOSE: We report our 4-year experience with deep dorsal vein arterialization at 3 years' follow-up in young patients with pure cavernoocclusive dysfunction as an alternative to penile prosthesis implantation. MATERIALS AND METHODS: We performed a modified Furlow-Fisher operation (circumflex collaterals are preserved and the deep dorsal venous valves are not disrupted by a stipper) in 25 patients who did not have risk factors such as general arteriosclerosis, coronary heart disease, hypertension, hyperlipidemia and age (over 40 years). Patients with arterial disease diagnosed by Doppler examination were excluded from the study. Also, patients with abnormal penile biothesiometric and electromyographic findings were not included in the study. Beside the subjective and objective evaluation the efficacy of the operation was also assessed retrospectively in 18 patients by telephone according to items 3 (ability to achieve an erection) and 4 (ability to maintain an erection) of the 15-item International Index of Erectile Function (IIEF). RESULTS: With a mean follow-up of 28 months (range 4-42) subjective and objective success rates were 80 and 72% at 1 year's 75 and 62.5% at 2 years', and 70 and 60% at 3 years' follow-up. According to items 3 and 4 of the 15 item IIEF questionnaire the mean postoperative scores reached 1.55-3.44 and 1. 33-3.27 for items 3 and 4, respectively (p<0.01). Two patients (8%) showed signs of glans hypervascularization as a major complication and minor complications such as penile skin edema, subdermal hematoma, loss of penile skin sensation and early thrombosis of the anastomosis were found in a total of 8 patients (32%). CONCLUSIONS: Deep dorsal vein arterialization is a preferable choice in highly selected young patients as an alternative to penile prosthesis.

Adult↗
PubMed2000

Studies on the expression of endothelin, its receptor subtypes, and converting enzymes in lung cancer and in human bronchial epithelium.

Lung cancer, particularly small cell lung cancer (SCLC), is characterized by production of numerous peptides and their resulting clinical syndromes. Such peptides can act as autocrine growth factors for these tumors. In this study, we investigated the role of endothelin (ET)-1 in lung cancer. Using reverse transcription/polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay, and immunocytochemistry, we screened a panel of lung cancer cell lines for ET-1, its receptors, and endothelin converting enzyme-1 (ECE-1), which generates the active form of ET-1. ET-1 messenger RNA was expressed in five of seven SCLC, four of four non-small cell lung cancer (NSCLC), and human bronchial epithelial (HBE) cells. The intracellular isoform of ECE-1, important in processing ET-1 if an autocrine growth loop is to function, was downregulated in the lung cancer cell lines as compared with expression of the extracellular isoform. Endothelin A receptor (ETAR), which mediates the mitogenic effects of ET-1 in prostate and ovarian cancer, was upregulated in HBE cells compared with expression in three of seven SCLC and two of four NSCLC cell lines. Endothelin B receptor (ETBR) was more widespread, being expressed in seven of seven SCLC, four of four NSCLC, and the HBE cells. We used flow cytometry to measure mobilization of intracellular calcium as a functional assay for the ETAR. These data concurred with the RT-PCR results, indicating that the ETAR was downregulated or was involved in an alternative signal transduction pathway in lung cancer, and no evidence of functional receptor mediating an autocrine growth loop was found. From our study, the data do not support the putative functional autocrine growth role of ET-1 in lung cancer. We propose instead that ET-1 may act as a paracrine growth factor for surrounding epithelial and endothelial cells via alternative pathways, promoting angiogenesis and stromal growth.

Aspartic Acid Endopeptidases↗
PubMed1995

Effect of some psychoactive drugs on stress induced alteration in plasma corticosterone level.

Psychoactive drugs such as chlorpromazine, fluphenazine, haloperidol, propranolol and diazepam were evaluated for their ability to block stress induced changes in Wistar albino rats. The stress induced changes were monitored as the difference in plasma corticosterone (PCS) levels, before and after the administration of minimum effective doses of psychoactive drugs. Significant results were obtained with diazepam at the dose of 5-10 mg/kg and to a lesser extent with propranolol 20 mg/kg. Other drugs, at their minimum effective doses showed no significant change in plasma corticosterone levels.

Animals↗
PubMed1994

Emergence of multi-drug resistance among beta-lactamase producing Salmonella.

Multi-drug resistant strains of Salmonella isolated from blood and bone marrow cultures of pyrexial patients received from physicians, hospitals and different clinics were studied from May to November, 1993. Of 2143 samples collected, 424(20%) cases yielded the growth of different organisms. Out of these 266(63%) were positive for Salmonella strains. The strains isolated were Salmonella typhi 239(90%) and Salmonella paratyphi A 27(10%). Two hundred twenty (82%) strains of Salmonella showed increased beta-lactamase activity and an alarming increase in resistance against commonly used antibiotics for enteric fever.

4-Quinolones↗
PubMed1978

Effects of essential amino acid deficiencies on syngeneic tumor immunity and carcinogenesis in mice.

The present study was designed to evaluate in a syngeneic system the longterm effect of dietary reduction of each of three essential amino acids on carcinogenesis with methylcholanthrene (MCA) and immunity to a transplanted MCA tumor. Inbred mice were provided a standard amino acid diet or a diet deficient in isoleucine, leucine, or phenylalanine-tyrosine. In the carcinogenesis experiment, MCA pellets were implanted in each mouse and weekly records were maintained of body weight, tumor incidence, tumor size, and death rate. Mice in the immunity study were inoculated with syngeneic tumor cells; tumors were excised when the largest tumor in the control group reached 12 mm and each animal then received a second challenge of tumor cells. The available data suggest that (1) restriction of the selected amino acids does not inhibit chemical carcinogenesis with MCA, (2) phenylalanine-tyrosine deficiency may actually enhance chemical carcinogenesis with MCA, and (3) selected essential amino acid deficiencies do not enhance immunity to a transplanted MCA tumor.

Amino Acids, Essential↗
PubMed1976

Purification and properties of threonine deaminase from Saccharomyces cerevisiae.

Threonine deaminase (L-theonine hydro-lyase (deaminating), E.C. 4.2.1.16) has been purified to homogeneity from extracts of Saccharomyces cerevisiae. When purified 1200-fold, the enzyme is homogeneous by the criterion of sodium dodecyl sulfate-polyacrylamide electrophoresis. The reduced and alkylated protein has a molecular weight of approximately 50,000 daltons, one-fourth the value determined previously for the intact enzyme. The purified enzyme exhibits homotropic effects with the substrate; these effects are descresed in the presence of DL-allothreonine, a competitive inhibitor. Half-maximal velocity is achieved at 34 mM L-threonine in the absence of other effectors. L-isoleucine both stimulates at low (0.01-0.05 mM) concentrations and inhibits at high (0.1-1.0 mM) concentrations. Valine activates the enzyme in the absence of isoleucine ; in the presence of isoleucine it reverses inhibition.

Hydro-Lyases↗
PubMed1976

Recurrent urinary tract infection due to Shigella flexneri--case report.

A case of urinary tract infection due to Shigella Flexneri is reported. The case presented suggests that in persistent and recurrent urinary tract infection in topical countries, investigations for organisms such as Shigella Flexneri should be considered. Urinary tract infection due to Shigella Flexneri is unknown and as far as we known has not been reported in the literature. A case report is presented in whom recurrent urinary tract infection was due to Shigella Flexneri and was treated effectively with antibiotics.

Ampicillin↗