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Biomedical subjects

S Ahmed

Publications and source records attributed to S Ahmed.

At least 325 records · Page 18Linked to original sources
PubMed1997

Prediction of renal function recovery in obstructive renal failure due to stones.

Two hundred and thirty-nine patients with renal and ureteric calculi associated with renal failure were evaluated for recovery potential before definitive surgery. Ultrasonography was carried out pre-operatively in all, followed by percutaneous nephrostomy (PCN) as an initial management before definitive surgery. Diethylene triamine penta acetic acid (DTPA) scan was done in 125 patients after percutaneous nephrostomy, findings of pre- operative DTPA scan were correlated with post-operative drop in serum creatinine. Urine pH, urine Na+, initial diuresis, creatinine clearance and serum creatinine were measured serially after 24 hours and then every week for 6 weeks. Patients were re-evaluated with serum creatinine after 3 months of surgery. Ultrasonography was found to be reliable in predicting future recovery of renal functions in 76.5% cases and true obstruction of shorter duration (F4-group) on DTPA scan in 81.9% cases. Urine pH of 6 or less, post-PCN diuresis and natriuresis were good prognostic indicators. PCN was found to be most reliable method of predicting future recovery of renal function after relief of obstruction with 97.8% accuracy.

Adult↗
PubMed1997

IgA nephropathy in teaching hospitals of Dhaka.

A light and immunofluorescence microscopic study on renal biopsies were performed on 42 patients. Nephrotic syndrome with accompanying microhematuria and recurrent hematuria (Macroscopic/microscopic) with or without renal failure were the commonest indications for renal biopsy. Primary IgA nephropathy was diagnosed in five cases. Among the IgA nephropathy patients, the commonest light microscopic finding was mesangial proliferative glomerulonephritis. Macroscopic hematuria with proteinuria was the commonest feature. Three of the patients had hypertension at the time of renal biopsy. The age of the patients ranged from 19-38 years with a mean of 26 years. The high frequency of hypertension, degree of proteinuria and associated renal failure in one patient that it is a progressive disease. This preliminary study revealed that IgA nephropathy exists in Bangladesh. Larger samples need to be studied with a view to find out its prevalence and its peculiarities in this part of the world.

Adult↗
PubMed1997

Stereoselectivity in cutaneous hydrolysis and transdermal transport of propranolol prodrug.

This review is written to evaluate the stereoselectivity in cutaneous hydrolysis and transdermal transport of propranolol prodrug. This discussion will be useful in the development of knowledge about stereoselective cutaneous hydrolysis and its influence on stereoselective transdermal transport of many other chiral prodrugs and drugs. Propranolol prodrugs undergo stereoselective hydrolysis in hairless mouse skin homogenate and in excised skin samples during permeation; the stereoselectivity is markedly biased towards hydrolysis of the (R) isomer. Unlike the liver, the esterase activity of the skin is high in its cytosolic fraction. Most of the lipophilic propranolol prodrugs cause stereoselective permeation across hairless mouse skin. A mechanism of stereoselective permeation of propranolol prodrug across the skin has been proposed, which indicates that the stereoselectivity in permeation is resulted from the stereoselective hydrolysis of lipophilic prodrug during permeation.

Animals↗
PubMed1996

The Ras-related GTPase Rac1 binds tubulin.

The Ras-related Rho family are involved in controlling actin-based changes in cell morphology. Microinjection of Rac1, RhoA, and Cdc42Hs into Swiss 3T3 cells induces pinocytosis and membrane ruffling, stress fiber formation, and filopodia formation, respectively. To identify target proteins involved in these signaling pathways cell extracts immobilized on nitrocellulose have been probed with [gamma-32P]GTP-labeled Rac1, RhoA, and Cdc42Hs. We have identified two 55-kDa brain proteins which bind Rac1 but not RhoA or Cdc42Hs. These 55-kDa proteins were abundant, had pI values of around 5.5, and could be purified by Q-Sepharose chromatography. The characteristics on two-dimensional gel analysis suggested the proteins comprised alpha- and beta-tubulin. Indeed, beta-tubulin specific antibodies detected one of the purified 55-kDa proteins. Rac1 bound pure tubulin (purified by cycles of polymerization and depolymerization) only in the GTP-bound state. The GTPase negative Rac1 point mutants, G12V and Q61L, did not significantly affect the ability of Rac1 to interact with tubulin while the "effector-site" mutant D38A prevented interaction. These results suggest that the Rac1-tubulin interaction may play a role in Rac1 function.

3T3 Cells↗
PubMed1996

Randomized trial of blunt-tipped versus cutting needles to reduce glove puncture during mass closure of the abdomen.

Eighty-five consecutive patients were randomized to undergo mass closure of the abdomen with no. 1 polydioxanone mounted on either a blunt-tipped (n = 46) or cutting (n = 39) needle. Gloves were changed before closure and tested for perforation afterwards using standard air or water techniques. Fourteen pairs of gloves were punctured when using a cutting needle, and three pairs when a blunt-tipped needle was used. The majority of punctures were to the non-dominant glove. The surgeon was aware of the puncture in eight of the 14 instances involving a sharp needle and in one of the three involving a blunt-tipped needle. Blunt-tipped needles, while not eliminating the risk, significantly reduced the incidence of surgical glove puncture (P < 0.001, Fisher's exact test). The use of cutting needles for abdominal closure should be abandoned.

Abdomen↗
PubMed1996

Electrogastrography in chronic intestinal pseudoobstruction.

This study aimed to characterize the disturbance of gastric electrical control activity in chronic intestinal pseudoobstruction (CIP) and to determine whether surface electrogastrography (EGG) could be used to diagnose the presence and type of CIP. Gastric electrical control activity was recorded for 30 min in each of the fasting and fed states by EGG in 14 adults with CIP proven on clinical, radiological, and histological grounds, and in 14 age- and sex-matched controls. Electrical activity was recorded from four pairs of Ag-AgCl bipolar skin electrodes, the captured signal amplified and digitalized, and running spectral analysis performed. The dominant frequency and power of spectrum were calculated using a sequence of computerized algorithms. Results were correlated with the known pathological diagnoses [visceral myopathy (M), N = 7; visceral neuropathy (N), N = 4; undifferentiated (U), N = 3]. Dysrhythmias were present in 13 of 14 patients. Tachygastria (electrical control activity frequency >5 cycles/minute) and a normal amplitude response to food, was seen in five patients (N = 4, U = 1). Irregular continuous activity without a dominant frequency or bradyarrhythmia, together with a diminished electrical response activity (ERA) to food, were found in six patients (M = 5, U = 1). Mixed abnormalities were seen in two patients (M = 1, U = 1), and normal activity with a clear dominant frequency of 3 cycles/minute was present in only one patient (M = 1). This noninvasive technique is both sensitive and specific in providing evidence of a dysrhythmia in patients with CIP and discriminates between primary pathologies. EGG may prove diagnostically useful in these disorders and may provide insight into the disturbance of electrical control activity.

Action Potentials↗
PubMed1996

Efficacy and toxicity of radiation in preparative regimens for pediatric stem cell transplantation. II: Deleterious consequences.

There has been a dramatic improvement in the treatment of both allogeneic and autologous stem cell transplants, especially in children and young adults. However, attempts to apply more intensive conditioning treatments to the more refractory pediatric malignancies have also increased the risks of deleterious consequences. This review examines the risks, and reports important variations in the toxic effects of using different conditioning techniques.

Child↗
PubMed1996

Surgical treatment alternatives in stress incontinence.

OBJECTIVES: This study was performed to evaluate the different surgical treatment alternatives for urinary stress incontinence and their clinical results. METHODS: Of the patients who visited our clinic between January 1989 and June 1994 complaining of urinary stress incontinence, 408 were found to have genuine stress incontinence (GSI) after undergoing clinical and laboratory investigations. These 408 patients were treated with different surgical techniques. Their postoperative results are discussed. RESULTS: After postoperative follow-up, the success rates of the different surgical techniques were as follows: anterior colporrhaphy (Kelly plication) 66.2%, Marshall-Marchetti-Krantz 88.7%, Burch procedure 94.1%, and sling urethropexy 97.5%. CONCLUSIONS: Patients with a clear-cut diagnosis of GSI must be surgically treated. There are several different techniques, all of which have advantages and disadvantages. If the right technique is used for the right patient then the success rate is high.

Adult↗
PubMed1996

Phase shifting the human circadian clock using melatonin.

Melatonin is produced only during nighttime darkness. Its onset during the evening is a useful marker for circadian phase position, when melatonin levels are sampled frequently and under conditions of dim light or darkness. This marker is termed the dim light melatonin onset (DLMO). Recently, we have described a phase response curve (PRC) to melatonin in humans that is about 12 h out of phase with the PRC to light. Exogenous melatonin administration and bright light exposure can be used to shift circadian rhythms according to their respective PRCs. These phase-resetting agents can be used alone or together to treat circadian phase disorders, which include advanced and delayed sleep phase syndrome, shift work maladaptation, jet lag and winter depression. Endogenous melatonin may function to augment entrainment of circadian rhythms by the light-dark cycle.

Biomarkers↗
PubMed1996

Effect of postoperative mydriatics on the iris.

PURPOSE: To assess the role postoperative mydriatics play after extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (IOL) implantation in causing iris modifications and in controlling inflammation. SETTING: Outpatients Department, Ninewells Hospital, Dundee, Scotland. METHODS: The prospective study comprised 136 patients who had standardized ECCE. Half the patients used a mydriatic for 2 weeks postoperatively. Anterior chamber activity, pain, and eye redness were evaluated at 2 weeks postoperatively; pupil shape, peripheral anterior synechias, IOL position, and iris adhesions, at 6 weeks. RESULTS: Iris-lens adhesions were significantly more common in the group using a mydriatic. There was no difference between the two groups in postoperative inflammation. CONCLUSION: Mydriatics should not be used routinely after ECCE with posterior chamber IOL implantation.

Aged↗
PubMed1996

Evaluation of stereoselective transdermal transport and concurrent cutaneous hydrolysis of several ester prodrugs of propranolol: mechanism of stereoselective permeation.

PURPOSE: The purpose of this study was to evaluate the stereoselective permeation and concurrent cutaneous hydrolysis of a series of ester prodrugs of propranolol (PL). METHODS: In vitro studies were performed across full-thickness, stripped and diisopropylfluorophosphate (DFP) treated skins of hairless mouse with flow-through diffusion cells at 37 degrees C. RESULTS: The permeability coefficients (Kp), which were dependent on partition coefficients (PC), of all the prodrugs were markedly increased compared to the parent drug. In full-thickness skin, the (R) caproyl-PL (CR-PL) showed the highest Kp, which was about 52-fold greater than that of PL. Most of the more lipophilic prodrugs showed stereoselectivity in Kp (R > S). All the prodrugs underwent stereoselective hydrolysis (R > S) during penetration. The prodrugs which showed stereoselectivity in permeation were comparatively lipophilic and showed great differences in hydrolysis percentages between the enantiomers. Permeation studies with stripped skin revealed that prodrugs were more permeable across stratum corneum compared to PL, whereas reverse was happened across viable skin. Although CR-PL showed high stereoselectivity in permeation across full-thickness skin and underwent higher percent of concurrent stereoselective cutaneous hydrolysis, the prodrug showed no stereoselectivity in permeation across DFP, an esterase inhibitor, treated skin and the concurrent cutaneous hydrolysis was also stopped. CONCLUSIONS: Lipophilic prodrugs may readily pass the stratum corneum but may not be able to penetrate so easily through the deeper tissues. Unlike the (S) isomers, the (R) isomers of lipophilic prodrugs almost completely converted to propranolol in epidermis and can easily pass through the dermis layer, resulting in stereoselective penetration.

Administration, Cutaneous↗
PubMed1996

Urethral injury in girls with fractured pelvis following blunt abdominal trauma.

OBJECTIVE: To review the management of major urethral injury in three girls with fractured pelvis following blunt abdominal trauma. PATIENTS AND METHODS: Three girls aged 5 years, 1 year and 3 years sustained major urethral injury in association with fractured pelvis following blunt abdominal trauma. Initial management was undertaken elsewhere. Two girls, with complete loss of the urethra and a closed bladder base, were managed by construction of a neourethra using a flipped anterior bladder-wall tube. The third patient with extensive perineal soft-tissue loss and rupture of the bladder neck and urethra had a modified Young-Dees-Leadbetter bladder neck reconstruction. All three had an associated vaginal injury which did not require a specific surgical procedure. RESULTS: The two girls who underwent construction of a neourethra using a flipped anterior bladder-wall tube are continent. The first voids normally and the second is managed by clean intermittent catheterization. The patient who underwent bladder neck reconstruction is incontinent and further surgery, possibly a continent diversion, may be necessary. CONCLUSION: Pelvic fracture following blunt abdominal trauma in girls may be associated with major urethral injury, usually with an associated vaginal injury. Surgical ingenuity is required to repair such injuries successfully. In those with complete loss of the urethra, a flipped anterior bladder-wall tube neourethra is suitable.

Abdominal Injuries↗
PubMed1996

Continence after bladder-neck reconstruction in patients with bladder exstrophy and pubic diastasis.

OBJECTIVE: To review the results of bladder-neck reconstruction in patients with repaired bladder exstrophy and pubic diastasis. PATIENTS AND METHODS: Nine girls (mean age 7 years, range 4-17) and four boys (mean age 9 years, range 5-15) underwent a modified Young-Dees-Leadbetter bladder-neck reconstruction with augmentation cystoplasty (YDL-C). The patients were reviewed retrospectively (follow-up, 1-6 years) to assess continence, particularly in relation to the degree of pubic diastasis measured on an appropriate abdominal radiograph. RESULTS: Ten patients were continent; seven girls and one boy are managed by clean intermittent catheterization (CIC) and one girl and one boy void normally. One girl who would not allow CIC and one boy in whom CIC was not possible are incontinent and are scheduled for construction of a continent diversion. One incontinent boy who also would not allow CIC was lost to follow-up. Public diastasis had no bearing on the surgical results, the 10 continent patients having diastasis ranging from 4 to 9 cm (mean 5.5 cm) and the incontinent patients a diastasis of 3.4 and 6.5 cm (mean 4.5 cm). CONCLUSION: Young-Dees-Leadbetter bladder-neck reconstruction with augmentation cystoplasty is a satisfactory operation in patients with bladder exstrophy. We believe that the rate of continence reflected a competent tubularization with an adequate bladder capacity and assured bladder emptying. A closed pelvis with approximated public bones is not necessary to achieve this objective.

Adolescent↗
PubMed1996

Is prolonged breastfeeding associated with malnutrition? Evidence from nineteen demographic and health surveys.

BACKGROUND: A growing body of literature suggests that prolonged breastfeeding (typically defined as beyond the first year of life) may be a risk factor for malnutrition. METHODS: To examine the extent to which continued breastfeeding is a risk factor for malnutrition, we used multiple regression techniques to relate current breastfeeding status to weight and stature in children < 36 months old whose mothers participated in one of 19 Demographic and Health Surveys (DHS) conducted between 1987 and 1989. RESULTS: The data from 9 of 11 countries outside sub-Saharan Africa (SSA) indicated that among older children, those still breastfed are shorter and lighter than those no longer breastfed. These differences, which reached statistical significance in five countries, become apparent at 12-18 months of age. In contrast, in five of eight SSA countries, younger still breastfed children are significantly shorter and lighter than those no longer breastfed, but, the differences are largely diminished among older children. These basic patterns were not altered by adjustment for family sociodemographic characteristics, health care utilization, and recent child illness. CONCLUSIONS: Important differences in nutritional status associated with continued breastfeeding are observed throughout the developing world, and are not likely due to confounding by family sociodemographic characteristics, health care utilization or recent child illness. A unifying interpretation of the observed relationships is that child size is somehow related to the decision to wean, and that whereas in SSA, the biggest children are weaned first, in non-SSA countries, the smallest children are weaned last.

Age Factors↗
PubMed1996

Lipopolysaccharide-specific antibodies in plasma and stools of children with Shigella-associated leukemoid reaction and hemolytic-uremic syndrome.

Antibody responses to the lipopolysaccharide (LPS) of shigellae were compared between children with uncomplicated and complicated Shigella dysenteriae 1 infection. One hundred fifteen children between 12 and 60 months of age with S. dysenteriae 1 infection were studied. Of these children, 42 had complications (leukemoid reaction and/or hemolytic-uremic syndrome [complicated shigellosis] and 73 had no complications (uncomplicated shigellosis). Antibodies to the LPS of S. dysenteriae 1 and Shigella flexneri Y were measured in plasma and stools, as were total immunoglobulin A (IgA) and IgG concentrations in plasma and the total IgA concentration in stool, on enrollment and 3 to 5 days later. In the plasma, the concentrations of homologous (IgG) and heterologous (IgA) LPS antibodies on enrollment were higher in children with complicated shigellosis than in those with uncomplicated shigellosis. In stool, the concentrations on enrollment were similar between the two groups of children. There was a rise in antibody concentrations in the plasma (homologous and heterologous) and stool (homologous) between the day of enrollment and 3 to 5 days later in children with uncomplicated shigellosis but not in those with complicated shigellosis. These findings suggest that systemic stimulation is more marked in children with complications, so that a subsequent rise in plasma antibody concentrations does not occur in these children. In contrast, the lack of a rise in stool antibody concentrations in children with complicated shigellosis is suggestive of a lower-level mucosal response. Because the duration of diarrhea before enrollment influenced the homologous antibody concentrations, children were further divided into three subgroups (short [3 to 5 days], medium [6 to 9 days], and long [> 9 days] diarrhea durations before enrollment). Comparisons of homologous antibody concentrations between the two groups of children following such subdivisions showed that in children with complicated shigellosis, antibody concentrations were higher in the plasma of children in the short diarrhea duration subgroup but lower in the stool children in the medium diarrhea duration subgroup. No differences in antibody concentrations were observed in children in the other diarrhea duration subgroups. Thus, complications in shigellosis are associated with an early and strong systemic stimulation without a concomitant stimulation of the mucosal antibody response.

Antibodies, Bacterial↗
PubMed1996

The GTPase-activating protein n-chimaerin cooperates with Rac1 and Cdc42Hs to induce the formation of lamellipodia and filopodia.

n-Chimaerin is a GTPase-activating protein (GAP) mainly for Rac1 and less so for Cdc42Hs in vitro. The GAP activity of n-chimaerin is regulated by phospholipids and phorbol esters. Microinjection of Rac1 and Cdc42Hs into mammalian cells induces formation of the actin-based structures lamellipodia and filopodia, respectively, with the former being prevented by coinjection of the chimaerin GAP domain. Strikingly, microinjection of the full-length n-chimaerin into fibroblasts and neuroblastoma cells induces the simultaneous formation of lamellipodia and filopodia. These structures undergo cycles of dissolution and formation, resembling natural morphological events occurring at the leading edge of fibroblasts and neuronal growth cones. The effects of n-chimaerin on formation of lamellipodia and filopodia were inhibited by dominant negative Rac1(T17N) and Cdc42Hs(T17N), respectively. n-Chimaerin's effects were also inhibited by coinjection with Rho GDP dissociation inhibitor or by treatment with phorbol ester. A mutant n-chimaerin with no GAP activity and impaired p21 binding was ineffective in inducing morphological changes, while a mutant lacking GAP activity alone was effective. Microinjected n-chimaerin colocalized in situ with F-actin. Taken together, these results suggest that n-chimaerin acts synergistically with Rac1 and Cdc42Hs to induce actin-based morphological changes and that this action involves Rac1 and Cdc42Hs binding but not GAP activity. Thus, GAPs may have morphological functions in addition to downregulation of GTPases.

3T3 Cells↗
PubMed1996

The prognostic significance of previous benign breast disease for women with carcinoma of the breast.

BACKGROUND: Risk factors for carcinoma of the breast may also have prognostic influence. Because benign breast disease is a risk factor for carcinoma of the breast, we compared the outcomes of patients with carcinoma of the breast with a history of benign breast disease to patients with carcinoma of the breast without a history of benign breast disease. STUDY DESIGN: Patients with benign breast disease and subsequent carcinoma of the breast were matched by age and ethnicity to patients with carcinoma of the breast with no prior history of benign breast disease. Risk factors, pathologic findings, and disease-free survival rates were compared. RESULTS: Patients with previous benign breast disease had a significantly greater family history of carcinoma of the breast (35 percent compared with 22 percent, p = 0.015) and used postmenopausal hormones significantly more frequently (16 percent compared with 5 percent; p < 0.001) than women without benign breast disease. In patients with benign breast disease, their subsequent carcinomas were smaller (T1, 53 percent compared with 43 percent), with significantly fewer nodes involved (1.8 compared with 2.7, p = 0.031), and were significantly more likely to contain an infiltrating lobular component (9 percent compared with 3 percent, p = 0.023). Significantly fewer patients with previous benign breast disease had metastatic disease (18 percent compared with 31 percent; p = 0.001). The ten-year cumulative disease-free survival rate for patients with benign breast disease was 68 percent compared with 59 percent for women without a history of benign breast disease. CONCLUSIONS: This study indicates that women with benign breast disease who have carcinoma of the breast develop may have a better outcome than women without a history of benign breast disease.

Adult↗