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Biomedical subjects

I Ahmed

Publications and source records attributed to I Ahmed.

At least 19 recordsLinked to original sources
PubMed2006

Antimicrobial effect of silver-doped phosphate-based glasses.

In this study a range of phosphate-based glasses (PBG) doped with silver have been investigated for their antimicrobial activities. In disk diffusion assays, these compositions demonstrated microbistatic effects against a range of organisms including Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and Candida albicans. The data obtained from the above studies allowed for an additional range of PBG containing lower amounts of silver to be studied for their effects on the growth and viability of S. aureus, E. coli, and C. albicans. PBG containing 3 and 5 mol % Ag were bactericidal for S. aureus and E. coli and significantly decreased the growth rate of C. albicans. A decrease in the dissolution rates of the glasses was seen with increasing Ag content over the range of concentrations investigated. Overall, 3 mol % Ag incorporated into the PBG investigated was sufficient to mount a potent antibacterial effect against the test organisms, and these compositions also gave excellent long-term release of Ag ions into the medium.

Anti-Bacterial Agents↗
PubMed2006

Role of completion pancreatectomy as a damage control option for post-pancreatic surgical complications.

INTRODUCTION: Management of pancreatic leak and haemorrhage is complex with high mortality rates. In this study, the results of completion pancreatectomy which was performed as a last resort option were analysed. PATIENTS AND METHODS: 25 patients who had completion pancreatectomy from among 677 patients who had pancreatoduodenectomy or distal pancreatectomy over a period of 18 years were analysed in terms of the indications for completion pancreatectomy, outcome and survival data. RESULTS: Indications for completion pancreatectomy include pancreatic leak in 12 patients (48%), both bleeding and pancreatic leak in 8 (32%), and haemorrhage alone in 5 (20%) patients. 18 (72%) patients also had splenectomy. Median ITU stay was 4 and 8 days for those who survived and died post-completion pancreatectomy, respectively. 36% patients had septicaemia and 32% patients had multiple organ failure. 12 patients survived the operation with a median survival of 52 months. CONCLUSION: 25 (3.6%) patients required surgical intervention for pancreatic complications. The incidence of splenectomy was 84.6% in those who died after completion pancreatectomy compared to 58.3% of those who survived (Fisher's exact test two-sided 0.20). Despite significant morbidity and mortality, completion pancreatectomy has a role in the management of post-pancreatic surgical complications.

Adult↗
PubMed2006

Incidence of clinically significant bacteraemia in children who present to hospital in Kenya: community-based observational study.

BACKGROUND: Estimates of the burden of invasive bacterial disease in sub-Saharan Africa have previously relied on selected groups of patients, such as inpatients; they are, therefore, probably underestimated, potentially hampering vaccine implementation. Our aim was to assess the incidence of bacteraemia in all children presenting to a hospital in Kenya, irrespective of clinical presentation or decision to admit. METHODS: We did a community-based observational study for which we cultured blood from 1093 children who visited a Kenyan hospital outpatient department. We estimated bacteraemia incidence with a Demographic Surveillance System, and investigated the clinical significance of bacteraemia and the capacity of clinical signs to identify cases. RESULTS: The yearly incidence of bacteraemia per 100,000 children aged younger than 2 years and younger than 5 years was 2440 (95% CI 1307-3573) and 1192 (692-1693), respectively. Incidence of pneumococcal bacteraemia was 597 (416-778) per 100,000 person-years of observation in children younger than age 5 years. Three-quarters of episodes had a clinical focus or required admission, or both; one in six was fatal. After exclusion of children with occult bacteraemia, the incidence of clinically significant bacteraemia per 100,000 children younger than age 2 years or 5 years fell to 1741 (790-2692) and 909 (475-1343), respectively, and the yearly incidence of clinically significant pneumococcal bacteraemia was 436 (132-739) per 100,000 children younger than 5 years old. Clinical signs identified bacteraemia poorly. INTERPRETATION: Clinically significant bacteraemia in children in Kilifi is twice as common, and pneumococcal bacteraemia four times as common, as previously estimated. Our data support the introduction of pneumococcal vaccine in sub-Saharan Africa.

Anti-Bacterial Agents↗
PubMed2006

Effect of a novel pancreatic stent design on short-term pancreatic injury in a canine model.

BACKGROUND AND STUDY AIMS: Attempts to address the problem of injury to the pancreas by indwelling pancreatic stents are limited by our lack of knowledge of the pathogenesis of stent-induced injury and its relationship to stent morphology and the duration of stenting. The aim of our study was to evaluate pancreatic injury induced by 1 week of stenting with a 5F indwelling pancreatic stent of novel design, the "wing stent." METHODS: Pancreatic stents (5F) were placed surgically in eight dogs; wing stents (WS-5F) were used in four dogs and conventional stents (CS-5F) in another four. Two dogs underwent duodenotomy without stent placement (controls). The pancreas was harvested for microscopy at 1 week. A pathologist who was unaware of the source of the specimens graded the pancreatic injury. RESULTS: Although pancreatic injury was observed in both the CS-5F and WS-5F groups after 1 week of indwelling pancreatic stenting, it was considerably less severe in the WS-5F group compared with the CS-5F group (1.01 +/- 0.10 vs. 1.63 +/- 0.14, P < 0.01). All components of pancreatic injury were affected, with the most dramatic differences noted in inflammation, fibrosis, and edema. The differences were most marked in the stented segment ( P < 0.001) and in the upstream segment of the pancreas ( P < 0.05). CONCLUSIONS: Indwelling conventional pancreatic stents can cause significant pancreatic injury even when left in place for only 1 week. A wing design can significantly ameliorate stent-induced changes.

Animals↗
PubMed2006

Prevalence study to elucidate the transmission pathways of Helicobacter pylori at oral and gastroduodenal sites of a South Indian population.

INTRODUCTION: Since the discovery of Helicobacter pylori (H. pylori), much progress has been made worldwide in the field of its epidemiology. In spite of these advancements, many aspects of epidemiology still remain unclear, particularly among populations with low socio-economic status. The present study was designed to elucidate the different routes of transmission of H. pylori in the Hyderabad (South India) population and to investigate the impact of certain factors, such as age, gender, and lifestyle. METHODS: Samples used for the study included saliva and biopsy samples of 400 symptomatic subjects from Hyderabad, India. The patients were retrospectively grouped, based on histopathology of the biopsy and 16S rRNA amplification of both saliva and biopsy as H. pylori positive and negative. RESULTS: This study showed that the prevalence of H. pylori in both saliva and biopsy samples increased with age. In addition, the H. pylori infection was found more commonly in the saliva and biopsy samples among males (64 percent and 60 percent, respectively) than females (53.3 percent and 64 percent, respectively). Similarly, 71.6 percent and 73.5 percent of those who consumed municipal water acquired H. pylori (which were respectively found in their saliva and biopsy samples) compared to a lesser proportion (12.6 percent and 12.6 percent, respectively) of those who consumed boiled or filtered water. The study also found that subjects who preferred home-cooked food (57.1 percent and 57.7 percent) showed a lower prevalence of H. pylori in saliva and biopsy samples, respectively, compared to those (80 percent and 88 percent) who frequently ate out. CONCLUSION: The results of the present study suggest that besides the oral-oral route, the transmission of H. pylori also takes place through the consumption of food prepared under unhygienic conditions. Consumption of municipal tap water also has a high impact in the transmission of H. pylori.

Adolescent↗
PubMed2005

Ultrasound-guided core biopsy for the diagnosis of lumps in the neck: results in 82 patients.

Ultrasound-guided core biopsy of nodes (n = 78) and other lumps (n = 4) in the neck allowed a firm histological diagnosis in 76 of 82 patients (93%). Of the remaining six patients, histological examination was equivocal in four and valueless in two. Of 18 patients with a diagnosis of lymphoma only 3 required excision of the node to provide additional information for the planning of treatment.

Adult↗
PubMed2005

Streptozotocin-induced diabetic nephropathy in rats: the role of inflammatory cytokines.

The role of inflammatory cytokines in the pathogenesis of diabetic nephropathy has been studied in streptozotocin-induced diabetic rats. Rat kidneys were examined by light and electron microscopy and kidney homogenates were also analyzed by Western blot and flow cytometry for the expression of markers of inflammation namely, CD4+ and CD8+ T cells, macrophages, MHC classes I and II, the proinflammatory cytokines tumor necrosis factor-alpha, interferon-gamma and nitric oxide (NO). Light and electron microscope examination revealed infiltration of mononuclear cells throughout the renal parenchyma, with the glomeruli being more severely affected especially at 8 months after disease induction. Western blot and flow cytometric analyses revealed the infiltrating cells to be CD4+ T cells, CD8+ T cells and macrophages. Western blot analyses also revealed increased expression of the proinflammatory and Th1 cytokines tumor necrosis factor-alpha, interferon-gamma as well as nitric oxide. Using flow cytometry, we have shown that the difference in expression of CD4+ T cells in control and diabetic kidneys is more significant at 1 month than at 8 months, while expression of CD8+ T cells is more significant at 8 months. We speculate therefore that diabetic nephropathy is probably initiated and driven by a Th1 process. CD8+ T cells, however, become more significant at later stages of the disease when tissue loss is evident. Since NO induction also occurs only after 8 months, we hypothesize that NO might be significant for the later stages of the disease. Our data implicate inflammation in the pathogenesis of diabetic nephropathy in view of the overexpression of the proinflammatory cytokines TNF-alpha and IFN-gamma and the cells that secrete them in the early and late phases of the disease.

Animals↗
PubMed2005

Effect of iron on the surface, degradation and ion release properties of phosphate-based glass fibres.

Phosphate-based glass fibres (PGF) have the unique characteristic of being completely soluble in an aqueous environment, releasing bioactive and biocompatible ions. They have been proposed as tissue engineering scaffolds for craniofacial skeletal muscle regeneration, where myoblasts are seeded directly onto the fibres. Studies have shown that these cells have a preference in their initial attachment to fibres of certain composition and size, which in turn control the rate of degradation. This study investigated the relationship between the surface properties, degradation properties and ion release (cationic and anionic species) by altering the chemical composition of the PGF. Iron oxide (Fe2O3) was incorporated into glasses containing P2O5 (50 mol%), CaO (30 mol%) and Na2O (20 mol%). Six glass compositions with Fe2O3 ranging from 0 to 5 mol% by replacing the equivalent Na2O mol% were investigated. Contact angle measurements showed that polar interactions occurring on the glass surfaces diminished with increasing Fe2O3 content. This behaviour was reflected in the estimated surface energies of the glasses, where the overall surface energy decreased with increasing Fe2O3 content due to the decrease in polar or acid/base component. The incorporation of up to 5 mol% Fe2O3 into PGF resulted in a significant reduction in the degradation rate (by two orders of magnitude), which can be related to the formation of more hydration resistant P-O-Fe bonds. However, the degradation rate increased with decreasing fibre diameter (comparing average diameters of 31.6 +/- 6.5 microm versus 13.1 +/- 1.3 microm) for a given mass of fibre, and this is related to the surface area to volume ratio. Taken together the results suggest that fibres with the larger diameters and containing 3-5 mol% Fe2O3 could initially be a more durable scaffold than ones with 1 or 2 mol% Fe2O3 for initial cell attachment.

Absorbable Implants↗
PubMed2005

Index for predicting mortality in elderly surgical patients.

BACKGROUND: The aim of the study was to validate a mortality index for use in patients over 65 years of age undergoing operative treatment or conservative management. METHODS: From a study conducted more than 20 years ago of elderly patients admitted with a surgical condition, 11 variables were identified as being significant in predicting mortality: age, white cell count, serum urea concentration, pulse rate, mean blood pressure, type of admission, urgency of operation, complexity of surgery, conservative management, and diagnostic categories of vascular disease and malignancy. Using multivariate logistic regression analysis, a mortality index was devised. This index was validated in a separate study of comparable patients treated in 1999-2001. RESULTS: Comparison of the derivation and validation data sets showed similarity in the distribution of variables with no significant difference in mortality (overall mortality rate 9.3 per cent for the derivation set versus 9.6 per cent for the validation set; chi(2) = 0.084, 1 d.f., P = 0.771). Tests of calibration and discrimination showed no significant difference in predicted to actual deaths, and the receiver-operator characteristic plots of the two data sets showed good discrimination. CONCLUSION: This mortality index was derived specifically for patients over 65 years of age receiving either operative or conservative treatment. It could be of use when counselling patients and their relatives about the possible outcome of treatment.

Aged↗
PubMed2005

Characterisation of antibacterial copper releasing degradable phosphate glass fibres.

Phosphate-based glass fibres (PGF) of the general formula Na(2)O-CaO-P(2)O(5) are degradable in an aqueous environment, and therefore can function as antibacterial delivery systems through the inclusion of ions such as copper. In this study, PGF with varying amounts of copper oxide (CuO) were developed for potential uses in wound healing applications. PGF with 0, 1, 5 and 10 mol% CuO were produced with different diameters and characterised in terms of structural and antibacterial properties. The effect of CuO and fibre pulling speed on the glass properties were investigated using rapid differential scanning calorimetry, differential thermal analysis and X-ray diffraction. The effect of two fibre diameters on short-term (3 h) attachment and killing against Staphylococcus epidermidis were investigated and were related to their rate of degradation in deionised water, as well as copper ion release measured using ion chromatography. Thermal analysis showed that there was a significant increase in the PGF glass transition temperature as the CuO content increased. There was a significant decrease in the rate of degradation with increasing CuO content and an increase in fibre diameter. Over 6 h, both the amount and rate of copper ions released increased with CuO content, as well as a reduction in fibre diameter thus increasing the surface area to volume ratio. There was a decrease in the number of viable staphylococci both attached to the CuO-containing fibres and in the surrounding environment.

Absorbable Implants↗
PubMed2005

Graded esophageal mucosal ablation with cryotherapy, and the protective effects of submucosal saline.

BACKGROUND AND STUDY AIMS: Knowledge about the extent of damage with endoscopic cryotherapy is of critical importance before its potential as an ablative therapy is explored. The aims of this study were to evaluate the extent of transmural esophageal necrosis at 48 hours after cryospraying for varying durations, using a novel device based on the Joule-Thomson effect and with carbon dioxide as the refrigerant gas, and to examine the role of submucosal injection of saline in preventing deeper injury. METHODS: Cryospray was applied to several different segments of the esophagus for various lengths of time (15, 30, 45, 60, and 120 seconds) in a pig model. In another set of experiments performed subsequently, 2 ml of saline was injected into the submucosa and cryospray was applied for 60 seconds. RESULTS: Esophageal cryotherapy resulted in a dose-dependent injury to the esophagus: esophageal necrosis was minimal or limited to the mucosa after 15 seconds of cryospraying, extended to involve the submucosa after 30 seconds of cryospraying, and involved the muscularis propria also after 45 seconds, with frank transmural necrosis found after 120 seconds of cryotherapy. Prior submucosal saline injection protected against muscular necrosis from prolonged cryotherapy. CONCLUSIONS: We have shown a dose-dependent effect of cryotherapy on esophageal mucosal ablation. When more extensive lesions are encountered, it may be advisable to consider using submucosal saline injections as an additional safeguard against deeper injury.

Animals↗
PubMed2005

Histological, histochemical and electron microscopic changes of the placenta induced by maternal exposure to hyperthermia in the rat.

Both clinical and experimental investigations have shown that maternal hyperthermia during critical stages of embryo development can induce malformations in the offspring. Studies of the effect of heat stress on the placental functions are limited to the ewes, but that on microscopic structure is unknown. In the present study, rats were exposed to 41 or 42 degrees C for 1 h on gestation day (GD) 9. The controls were sham treated. Fetuses and placentas were collected on GD 20. Intrauterine growth retardation (IUGR) and several craniofacial malformations were observed in the fetuses of the heat-treated group. The placentas of the 42 degrees C group were significantly lighter in weight than those of the control. Light microscopy (LM) revealed thickening, hyalinization and occasional lymphocytic infiltration of the decidua basalis. Giant cells were prominent and glycogen cells had degenerated, leaving behind large cysts in the basal (spongy) zone. Best's carmine stain with or without diastase indicated the reduction in number and degeneration of glycogen cells and cyst formation. The labyrinthine zone was relatively thin in comparison to that of the controls. Perivascular fibrosis and paucity of vascularization were other features of the placentas of the hyperthermia group. Electron microscopy (EM) revealed lipid droplet accumulation in the trophoblast, the presence of myelin bodies and an increased production of collagen in the basal zone. Perivascular fibrosis appeared to have contributed to placental barrier thickening. EM also revealed accumulation of glycogen and lipid droplets in the trophoblasts and fibrin secretion into the extracellular space of the labyrinthine zone. These data suggest that placental pathology possibly contributes to fetal growth retardation in maternally heat-stressed rat fetuses.

Animals↗
PubMed2005

Intratesticular varicocele.

Extratesticular varicocele is a common clinical condition, occurring in up to 20% of the normal adult male population. It is characterized by dilatation of the veins of the spermatic cord and has well-described sonographic appearances. Intratesticular varicocele is characterized by dilated intratesticular veins and is extremely rare. It usually, but not always, occurs in association with an ipsilateral extratesticular varicocele. We describe the sonographic and colour Doppler appearances of this poorly described entity in a middle-aged man referred for evaluation of a painful left testicular swelling.

Adult↗
PubMed2005

Accuracy of intraoperative retinoscopy in corneal power and axial length estimation using a high plus soft contact lens.

AIM: To assess the accuracy of intraoperative retinoscopy with high plus soft contact lens (CL) in estimating corneal power and the axial length compared with standard keratometry and biometry measurement. METHODS: Intraoperative retinoscopy was performed in 30 eyes prior to the implantation of an intraocular lens (IOL). A +10 D disposable soft contact lens was applied on the cornea to minimize retinoscopic error. Corneal power was derived from refraction using biometric axial length while the axial length was derived using keratometric measurement. Refraction derived corneal powers and axial lengths from 26 eyes within +/-1.00 D of the target postoperative refraction were compared with preoperative standard keratometry and biometry measurements. RESULTS: In the 26 eyes, the mean difference between the corneal powers derived from refraction and keratometry was 0.35 D (S.D.=1.678). The 95% limits of agreement were -3.006 to +3.706. The mean difference between the axial lengths derived from refraction and biometry was 0.15 mm (S.D.=0.721). The 95% limits of agreement were -1.292 to 1.542. CONCLUSION: Intraoperative retinoscopy with a high plus soft contact lens after phacoemulsification is useful but not accurate in estimating corneal power or axial length of the eye. It should be used cautiously in IOL power calculation as a substitute for standard keratometry or biometry machines when either of these is not available or in error.

Aged↗
PubMed2005

Quantification of anion and cation release from a range of ternary phosphate-based glasses with fixed 45 mol% P2O5.

This article reports on the use of ion chromatography (IC) to investigate extensively the release profiles of both cations and anions and characterize the relationship between composition and degradation for a ternary-based Na(2)O-CaO-P(2)O(5) glass system developed as biomaterials. Studies are carried out on glasses with the formula 45P(2)O(5)-55(xCaO-Na(2)O) in deionized water, where x = 30, 35, and 40 mol%, using a cumulative release method, where the solution is changed at regular intervals. Degradation behavior is linear with time where the degradation rate shows an initial decrease with increasing CaO content. This rate then increases with a further addition of CaO. Cation release profiles follow similar trends to the degradation rates. Anion release profiles show a decrease for the PO(4) and linear polyphosphate (P(2)O(7) and P(3)O(10)) species with increasing CaO content. This decrease is attributed to the cross-linking of the Ca(2+) ions. In contrast, the cyclic P(3)O(9) anion exhibits the highest amount of anionic release, which demonstrates similar trends to the cations. These release patterns suggest that the cyclic P(3)O(9) species dominate the degradation rates. The proposed mode of degradation is a hydrolysis reaction, with the cyclic metaphosphate undergoing acid/base catalysis. The pH remains constant for the 30 and 35 mol% CaO glasses, and drops to about 5.5 for the 40 mol% composition. By using a response factor, it is possible to semiquantitatively analyze the additional peaks observed in the chromatograms. Suggestions are also put forward as to the identity of some of these unidentified peaks.

Absorbable Implants↗
PubMed2005

A review of ENT consultant postal questionnaires.

In recent years, there appears to have been an increase in the number of postal questionnaires being received by ENT consultants. Questionnaires with unsound methodology waste the time of those who send and receive them, as inferences cannot be made from their results. In this study,a review was performed on a sample of 19 questionnaire studies published in two ENT journals between January 1998 and December 2002. Each study was given a 30-point score, based on the quality of its methodology. The average score assigned to each study was 32 percent, suggesting that the quality of methodology was generally poor. These results should serve as a warning to those embarking on and those interpreting research of this kind.

Consultants↗