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Biomedical subjects

M Ahmad

Publications and source records attributed to M Ahmad.

At least 37 records · Page 2Linked to original sources
PubMed2004

Is there a correlation between degree of viremia and liver histology in chronic hepatitis C?

OBJECTIVE: To determine the correlation between degree of histological liver damage and serum HCV RNA level in patients of chronic hepatitis C, in order to evaluate the usefulness of HCV RNA estimation as an alternate to liver biopsy. METHODS: This non-interventional descriptive study, was carried out at the department of Pathology, Army Medical College, Rawalpindi, Pakistan between April and September 2002. Core needle liver biopsies of fifty five patients of chronic hepatitis C were evaluated according to Knodell's histological activity index system. The patients were categorized into four subgroups depending upon the grade and stage of disease according to Desmet's classification, and into three groups according to degree of viremia. RESULTS: Five patients had mild viremia, 43 moderate and 7 had severe viremia. Seven patients had minimal disease, 9 mild, 22 moderate and 17 had severe chronic hepatitis. Eight patients had no fibrosis, 20 had fibrous portal expansion, 19 bridging fibrosis, and 8 patients had cirrhosis. No significant correlation was found between serum HCV RNA levels and grade or stage of the disease, with correlation coefficients of rs = -.054 and rs = .034 respectively. Moreover, no individual component of the HAI correlated with serum HCV RNA levels. CONCLUSION: Serum HCV RNA level does not determine the degree of hepatic injury precisely and liver biopsy is necessary to accurately evaluate the extent of liver damage.

Adolescent↗
PubMed2004

Emphysematous renal tract disease due to Aspergillus fumigatus.

Emphysematous renal tract disease (ERTD) is a rare necrotizing infection of renal parenchyma and/or urinary tract caused by gas producing organisms. A case of acute emphysematous renal tract disease (ERTD) (emphysematous pyelonephritis along with emphysematous cystitis) caused by Aspergillus fumigatus in a non-diabetic patient, who did not apparently have any risk factor for fungal infection, is presented. Patient had refused for any surgical intervention. He was treated successfully with liposomal amphotericin B and 5-flucytosin and achieved complete recovery. Various causes of ERTD and available therapeutic options are discussed.

Adult↗
PubMed2003

Experimental determination of the lifetime for the 2p3d(1P0) helium doubly excited state.

Two recent theoretical studies [C. Liu, Phys. Rev. A 64, 010501 (2001)]; M. Zitnik, ibid. 65, 032520 (2002)]] predict that the fluorescence lifetimes of helium doubly excited states converging to He+ N=2 should be longer than that of the He+ 2p ion state. This effect is caused by the electric field of the outer electron which, through Stark mixing, gives the inner fluorescing electron some series specific, stabilizing 2s character. We have obtained the first experimental evidence that confirms this effect by measuring the lifetime of the 2p3d(1P0) doubly excited state. This was determined to be 190+/-30 ps compared to 100 ps for the He+ 2p ion state. The measurements were performed using short pulses of synchrotron radiation to form doubly excited states and recording the arrival time of photons from fluorescence.

Journal Article↗
PubMed2003

Acute left ventricular failure after large volume pericardiocentesis.

This paper reports on two cases of large volume pericardiocentesis followed by transient severe acute left ventricular (LV) systolic failure in the absence of any prior history of LV dysfunction. Acute LV volume overload due to interventricular volume mismatch is believed by most authors to be the cause for this phenomenon. Another plausible physiopathologic explanation is the acute increase in "wall stress" (Laplace's law) due to acute distention of the cardiac chambers secondary to a sudden increase in venous return at high filling pressures, combined with a "vacuum" effect of the evacuated pericardial space.

Adult↗
PubMed2003

Molecular mechanisms of N-acetylcysteine actions.

Oxidative stress generated by an imbalance between reactive oxygen species (ROS) and antioxidants contributes to the pathogenesis of arthritis, cancer, cardiovascular, liver and respiratory diseases. Proinflammatory cytokines and growth factors stimulate ROS production as signaling mediators. Antioxidants such as N-acetylcysteine (NAC) have been used as tools for investigating the role of ROS in numerous biological and pathological processes. NAC inhibits activation of c-Jun N-terminal kinase, p38 MAP kinase and redox-sensitive activating protein-1 and nuclear factor kappa B transcription factor activities regulating expression of numerous genes. NAC can also prevent apoptosis and promote cell survival by activating extracellular signal-regulated kinase pathway, a concept useful for treating certain degenerative diseases. NAC directly modifies the activity of several proteins by its reducing activity. Despite its nonspecificity, ability to modify DNA and multiple molecular modes of action, NAC has therapeutic value for reducing endothelial dysfunction, inflammation, fibrosis, invasion, cartilage erosion, acetaminophen detoxification and transplant prolongation.

Acetylcysteine↗
PubMed2003

Interwell tracing by environmental isotopes at Fimkassar Oilfield, Pakistan.

Water flooding is an important operation to enhance oil recovery. Movement of injected water is traced to test the performance of the water flood and verify suspected geological barriers or flow channels, etc. This paper describes the application of environmental isotopes as interwell tracers at Fimkassar Oilfield in Chakwal District, Pakistan. Water flooding was started in March 1996 in the Sakessar formation (Eocene). When water appeared in the production well in June 1998, isotopes (18O, 2H and 3H) were used to determine the breakthrough/transit time of the water flood and the contribution of fresh injected water. Water samples were collected during June 1998-August 1999 from the injection well, the production well, and some other fields for reference indices of the Sakessar formation and analyzed for the 18O, 2H and 3H, and chloride contents. The isotopic results confirmed the breakthrough of injected water and indicated that the water in the production well was a mixture of the injected water and the formation water. The initial breakthrough time was 27 months. The contribution of injected water varied from 67% to 80%. This percentage did not change significantly from the time of breakthrough until the last sampling indicating good mixing in the reservoir and the absence of any high permeability channel. Chloride content did not give any information about the hydraulic connection between the injection well and the production well. The study proved the potential of environmental isotopes for interwell tracing.

Journal Article↗
PubMed2003

Predictors of gastrointestinal complications after conventional and beating heart coronary surgery.

BACKGROUND: Gastrointestinal complications after cardiac surgery remain a significant problem despite improvements in pre-operative, operative and post-operative care. The pathophysiology is uncertain, and their prevention remains suboptimal. This prospective, randomised study was designed to define the role of cardiopulmonary bypass (CPB) and cardioplegic arrest in the pathogenesis of gastrointestinal complications following coronary artery surgery. METHODS AND RESULTS: Three hundred patients were prospectively randomised to (1) on-pump conventional coronary artery surgery [150 patients, 114 men, mean age 64 (45-75 years)] with mild hypothermic (32c) CPB and cardioplegic arrest of the heart or (2) off-pump surgery [150 patients, 113 men, mean age 64 (38-66) years] on the beating heart. The association of perioperative factors with gastrointestinal complications was investigated by univariate analysis. Significant variables were then included into a stepwise logistic regression model to ascertain their independent influence on the occurrence of gastrointestinal complications. There were no significant baseline differences between the groups. Eleven patients in the on-pump group and one patient in the off-pump group had post-operative gastrointestinal complications. Univariate analysis showed that CPB inclusive of cardioplegic arrest, left ventricular ejection fraction <50%, emergency surgery, prolonged aortic cross clamp and CPB time, post-operative low cardiac output syndrome, post-operative inotropic requirement, new onset atrial fibrillation (AF), excessive post-operative blood loss and redo thoracotomy <24 hours were predictors of gastrointestinal complications after coronary artery surgery (all p<0.05). However, stepwise multivariate regression analysis identified CPB inclusive of cardioplegic arrest as the only predictor of post-operative gastrointestinal complications (OR7.4; CI 3.4-17.9). CONCLUSIONS: Cardiopulmonary bypass, inclusive of cardioplegic arrest, is the main independent predictor of post-operative gastrointestinal complications in patients undergoing coronary revascularisation.

Aged↗
PubMed2003

A comparison of hepatoprotective activities of aminoguanidine and N-acetylcysteine in rat against the toxic damage induced by azathioprine.

Azathioprine (AZA) is an important drug used in the therapy of autoimmune system disorders. It induces hepatotoxicity that restricts its use. The rationale behind this study was the proven efficacy of N-acetylcysteine (NAC; a replenisher of sulfhydryls) and reports on the antioxidant potential of aminoguanidine (AG; an iNOS inhibitor), that might be useful to protect against the toxic implications of AZA. AG (100 mg/kg; i.p.) or NAC (100 mg/kg; i.p.) were administered to the Wistar male rats for 7 days and after that AZA (15 mg/kg, i.p.) was given as a single dose. This caused an increase in the activity of hepatic aminotransferases (AST and ALT) in the serum 24 h after AZA treatment. AZA (7.5 or 15 mg/kg, i.p.) also caused an increase in rat liver lipid peroxides and a lowering of reduced glutathione (GSH) contents. In the other part of experiment, protective effects of AG and NAC were observed on AZA induced hepatotoxicity. NAC significantly protected against the toxic effects produced by AZA. Pretreatment with NAC prevented any change in the activities of both the aminotransferases after AZA. This pretreatment also resulted in a significant decline in the contents of lipid peroxides and a significant elevation in GSH level was evident after AZA treatment. In the group with AG pretreatment the activities of AST and ALT did not increase significantly after AZA when compared to control. However, the lipid peroxides and GSH levels did not have any significant difference when compared to AZA group. These observations also indicate that the improvement in the GSH levels by NAC is the most significant protective mechanism rather than any other mechanistic profile. The protective effect of AG against the enzyme leakage seems to be through the liver cell membrane permeability restoration and is independent of any effects on liver GSH contents.

Acetylcysteine↗
PubMed2003

Validation of two air quality models for Indian mining conditions.

All major mining activity particularly opencast mining contributes to the problem of suspended particulate matter (SPM) directly or indirectly. Therefore, assessment and prediction are required to prevent and minimize the deterioration of SPM due to various opencast mining operations. Determination of emission rate of SPM for these activities and validation of air quality models are the first and foremost concern. In view of the above, the study was taken up for determination of emission rate for SPM to calculate emission rate of various opencast mining activities and validation of commonly used two air quality models for Indian mining conditions. To achieve the objectives, eight coal and three iron ore mining sites were selected to generate site specific emission data by considering type of mining, method of working, geographical location, accessibility and above all resource availability. The study covers various mining activities and locations including drilling, overburden loading and unloading, coal/mineral loading and unloading, coal handling or screening plant, exposed overburden dump, stock yard, workshop, exposed pit surface, transport road and haul road. Validation of the study was carried out through Fugitive Dust Model (FDM) and Point, Area and Line sources model (PAL2) by assigning the measured emission rate for each mining activity, meteorological data and other details of the respective mine as an input to the models. Both the models were run separately for the same set of input data for each mine to get the predicted SPM concentration at three receptor locations for each mine. The receptor locations were selected such a way that at the same places the actual filed measurement were carried out for SPM concentration. Statistical analysis was carried out to assess the performance of the models based on a set measured and predicted SPM concentration data. The value of coefficient of correlation for PAL2 and FDM was calculated to be 0.990-0.994 and 0.966-0.997, respectively, which shows a fairly good agreement between measured and predicted values of SPM concentration. The average index of agreement values for PAL2 and FDM was found to be 0.665 and 0.752, respectively, which represents that the prediction by PAL2 and FDM models are accurate by 66.5 and 75.2%, respectively. These indicate that FDM model is more suited for Indian mining conditions.

Air Pollution, Indoor↗
PubMed2003

HLA-DPB1*0401 is associated with dominant protection against type 1 diabetes in the general Saudi population and in subjects with a high-risk DR/DQ haplotype.

The human leukocyte antigen (HLA) class II DQB1*0201/0202-DRB1*04 genotype has been identified as predisposing to type 1 diabetes [insulin-dependent diabetes mellitus (IDDM)] in the Saudi Arabian population (P = 0.0002; odds ratio = 0.67; 95% confidence interval = 0.009-0.381). In this study, we searched for a factor at the DPB1 locus by analysing DPB1 polymorphism using sequence-based typing in 86 Saudi IDDM patients and control subjects, all carrying the HLA-DRB1*04/DQB1*02 haplotype or the known susceptibility allele DQB1*0201/0202. Significant protection was conferred by DPB1*0401, which was observed in 17 of 50 control subjects (55%) and 2 of 36 IDDM patients (5%) with the DQB1*0201/0202 allele (P = 0.0012; odds ratio = 8.75; confidence interval = 1.72-59.70). Our data showing a high frequency of the DPB1*0401 allele even in the presence of the predisposing DQB1*02 allele in healthy subjects may indicate a protective effect of this combination of HLA alleles against type 1 diabetes. This finding supports the hypothesis that protective HLA class II genes can override the risk conferred by HLA-DQ susceptibility alleles. Further studies using larger cohorts of control subjects and patients should be undertaken to confirm this observation.

Diabetes Mellitus, Type 1↗
PubMed2003

An analysis of consanguinity and social structure within the UK Asian population using microsatellite data.

We analysed microsatellite genotypes sampled from the Pakistani and Indian communities in Nottingham, UK, to investigate the genetic consequences of substructuring mediated by traditional marriage customs. The application of a recently developed likelihood approach identified significant levels of population substructure within the Pakistani community as a whole, as well as within the finer divisions of castes and biradheri. In addition, high levels of cryptic or unacknowledged consanguinity were detected within subgroups of this community, including biradheri. The Indian sample showed no significant evidence of either substructure or consanguinity. We demonstrate that estimates of disease gene frequencies can be inaccurate unless they are made jointly with estimates of population substructure and consanguinity ((theta congruent to FST) and C). The magnitude of these estimates also highlights the importance of accounting for the finer scale of social structuring when making decisions regarding the risk of recessive disorders in offspring.

Analysis of Variance↗
PubMed2003

Outcome of pregnancies in renal allograft recipients.

Despite documented success and long term safety of thousands of pregnancies in female renal allograft recipients in Western countries, pregnancy is still a rare event, and considered risky in India in these patients. Four initial cases with their adverse outcome in the Indian context are presented.

Adult↗
PubMed2003

Real-time 3-dimensional echocardiography. Technique and clinical applications.

This article will provide an overview of real time 3-dimensional (3D) echocardiography (RT-3D) in evaluation of patients with heart disease. We will briefly describe the technique and our experience in its clinical applications in patients with coronary artery disease, left ventricular apical thrombi, mitral stenosis and its role in guiding intracardiac catheter placement. Our extensive experience with application of RT-3D during dobutamine stress and during supine bicycle exercise indicates the technique is sensitive in detection of ischemia. RT-3D has been valuable in clearly identifying left ventricular apical thrombi in patients in whom 2-dimensional (2D) echo cannot firmly establish their presence or absence. We have utilized RT-3D in guiding myocardial biopsy in heart transplant patients and in precisely measuring mitral valve area before and after balloon valvuloplasty. RT-3D technique continues to evolve and should play an important role in assessment of patients with heart disease.

Computer Systems↗
PubMed2003

An autopsy study of hypertrophic cardiomyopathy.

OBJECTIVE: To see the pathological features of this disease in our set up and to emphasise the importance of morphological examination in making the diagnosis of hypertrophic cardiomyopathy (HCM) especially in cases of sudden cardiac death. METHODS: A retrospective, descriptive study of 15 autopsies of this particular disease was carried out at the Armed Forces Institute of Pathology (AFI) Rawalpindi during the period from 1990 to 1995. The hearts along with blood vessels were fixed in 10% formalin and were dissected according to the modified Virchow's method for eliciting the gross appearance of cardiac chambers and valves. Representative sections were taken for histological examination. RESULTS: All the cases were young adult males. The age range was from 17-34 years (mean, 26-6 years). Ten cases died suddenly and five cases had an evidence of moderate to severe exertion preceding their death. Symmetrical as well as asymmetrical hypertrophy was noted in this study. The thickness of inter ventricular septum (mean 20 mm) and left ventricular wall (mean 22.5 mm) was increased. All the specimens revealed disarray of hypertrophic myocardial fibres and patchy interstitial fibroses. CONCLUSION: Sudden death is usually the first manifestation of disease. The hearts showed asymmetric as well as concentric hypertrophy. Myofibre hypertrophy and disarray was an important pathological findings in our cases. While carrying out post-mortem examination of a case of sudden cardiac death one should also keep in mind the possibility of this disease.

Adolescent↗
PubMed2002

Mutation in the cartilage-derived morphogenetic protein-1 (CDMP1) gene in a kindred affected with fibular hypoplasia and complex brachydactyly (DuPan syndrome).

The present authors have previously described a consanguineous Pakistani family with fibular hypoplasia and complex brachydactyly (DuPan syndrome) inherited as an autosomal recessive trait. All affected individuals showed either reductions or absence of bones in the limbs, and appendicular bone dysmorphogenesis with unaffected axial bones. Obligate heterozygote parents were phenotypically normal. Mutations in the cartilage-derived morphogenetic protein 1 (CDMP1) gene have been reported in two acromesomelic chondrodysplasias (i.e. Hunter-Thompson type and Grebe type) which are phenotypically related to DuPan syndrome. CDMP1, a member of the transforming growth factor beta super-family of secreted signalling molecules, has been reported to regulate limb patterning and distal bone growth. Therefore, the present authors examined genomic DNA from the family with DuPan syndrome for mutations in the CDMP1 gene. Affected individuals were homozygous for a missense mutation, T1322C, in the coding region of the CDMP1 gene. This mutation was not found in 44 control subjects of Pakistani origin. The T1322C change predicts a leu441pro substitution in the mature domain of the CDMP1 protein. This is likely to cause a conformational change in the CDMP1 protein that influences the expression of genes which are required for normal bone development. This finding extends the spectrum of phenotypes produced by defects in the CDMP1 gene.

Bone Morphogenetic Proteins↗
PubMed2002

The effect of reproductive compensation on recessive disorders within consanguineous human populations.

We investigate the effects of consanguinity and population substructure on genetic health using the UK Asian population as an example. We review and expand upon previous treatments dealing with the deleterious effects of consanguinity on recessive disorders and consider how other factors, such as population substructure, may be of equal importance. For illustration, we quantify the relative risks of recessive lethal disorders by presenting some simple calculations that demonstrate the effect 'reproductive compensation' has on the maintenance of recessive alleles. The results show how reproductive compensation can effectively counteract the purging of deleterious alleles within consanguineous populations. Whereas inbreeding does not elevate the equilibrium frequency of affected individuals, reproductive compensation does. We suggest this effect must be built into interpretations of the incidence of genetic disease within populations such as the UK Asians. Information of this nature will benefit health care workers who inform such communities.

Alleles↗