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Biomedical subjects

A M Ahmed

Publications and source records attributed to A M Ahmed.

At least 19 recordsLinked to original sources
PubMed1999

Assessment of liver function by the MEGX test in patients with schistosomiasis and cirrhosis.

OBJECTIVES: The aim of this study was to determine the effect of schistosomiasis infection on hepatic function in Egyptian patients with posthepatitic cirrhosis. DESIGN AND METHODS: Hepatic function, was assessed in 66 Egyptian patients, with (n = 30) and without (n = 36) schistosomal liver fibrosis due to Schistosoma mansoni and in 20 healthy controls, using the monoethylglycinexylidide (MEGX) test. Serum MEGX concentrations were measured before and 5, 15, 30, 60, 120, and 180 min after a lidocaine bolus. The sero-prevalence of antibodies to hepatitis C was also determined in the patients. RESULTS: MEGX test results were significantly lower in patients than in controls at all time points. MEGX test results declined with advancing Child Class. Receiver operating characteristic (ROC) curve analysis revealed the following areas under the ROC curves for discrimination of Child Class C from Child Classes A/B: 30 min, 0.762; 60 min, 0.743; 120 min, 0.731; 15 min, 0.728; 180 min, 0.728; 5 min, 0.602. Schistosomiasis infection had no influence on MEGX test results when cirrhotic patients with (Schisto+) and without (Schisto-) schistosomiasis were compared. While the prevalence of the hepatitis B surface antigen was only 16.7% (Schisto-) and 26.7% (Schisto+), there was an extremely high sero-prevalence of antibodies to hepatitis C (HCV) in both groups: 88.9% (Schisto-) and 73.3% (Schisto+). CONCLUSIONS: The association of schistosomal liver fibrosis with cirrhosis does not additionally influence MEGX formation. In addition, HCV rather than schistosomiasis infection must be considered as a major cause for the progressive liver disease in these patients.

Adult↗
PubMed1999

Activation of human neutrophils by mycobacterial phenolic glycolipids.

The interaction between mycobacterial phenolic glycolipids (PGLs) and phagocytes was studied. Human neutrophils were allowed to interact with each of four purified mycobacterial PGLs and the neutrophil production of reactive oxygen metabolites was followed kinetically by luminol-/isoluminol-amplified chemiluminescence. The PGLs from Mycobacterium tuberculosis and Mycobacterium kansasii, respectively, were shown to stimulate the production of oxygen metabolites, while PGLs from Mycobacterium marinum and Mycobacterium bovis BCG, respectively, were unable to induce an oxidative response. Periodate treatment of the M. tuberculosis PGL decreased the production of oxygen radicals, showing the importance of the PGL carbohydrate moiety for the interaction. The activation, however, could not be inhibited by rhamnose or fucose, indicating a complex interaction which probably involves more than one saccharide unit. This is in line with the fact that the activating PGLs from M. tuberculosis and M. kansasii contain tri- and tetrasaccharides, respectively, while the nonactivating PGLs from M. marinum and M. bovis BCG each contain a monosaccharide. The complement receptor 3 (CR3) has earlier been shown to be of importance for the phagocyte binding of mycobacteria, but did not appear to be involved in the activation of neutrophils by PGLs. The subcellular localization of the reactive oxygen metabolites formed was related to the way in which the glycolipids were presented to the cells.

Antigens, Bacterial↗
PubMed1999

In vitro measurement of the tracking pattern of the human patella.

This study sought to determine whether a general pattern describing the three-dimensional tracking characteristics of the human patella could be established, and if not, then to determine the extent and nature of interspecimen variations in the characteristics in a normal population. Using 32 fresh-frozen knees subjected to extensor moment magnitudes similar to those in "static-lifting" and "leg-raising against resistance" maneuvers, patellar displacements were measured in the knee extension range 120 to 0 deg. For static-lifting, a constant foot-floor reaction of 334 N was applied. For leg-raising, a constant net quadriceps tension of 668 N was used throughout the extension range. Measurements were taken with a calibrated six-degree-of-freedom electromechanical goniometer and a displacement coordinate system referenced to the geometry of individual specimens. The three patellar displacements in the plane of knee extension/flexion (extension rotation, and anterior and proximal translations) consistently demonstrated the same pattern in the entire knee extension range with an average coefficient of variation of 13 percent. For knee angles greater than 45 deg, the three other displacements (medial-lateral translation, and rotations about the anterior--posterior and proximal--distal axes) followed a general pattern. However, for knee angles less than 45 deg, these displacements differed considerably between specimens for each loading condition, both in terms of magnitude (average coefficient of variation: 70 percent), and direction.

Adult↗
PubMed1996

Calculated stress-shielding in the distal femur after total knee replacement corresponds to the reported location of bone loss.

This study sought to determine the similarities between features of calculated stress-shielding and observed bone loss in the distal femur after total knee replacement. Stress-shielding was determined by comparing the magnitudes and distributions of strain energy density, calculated using three-dimensional finite element models of the intact bone, the bone after total knee replacement with bonding assumed at all prosthesis-bone interfaces, and the bone after total knee replacement with bonding assumed only at the distal interface. The loading condition simulated static lifting with the knee flexed at 45 degrees, producing tibiofemoral and patellofemoral joint reactions of 900 and 450 N, respectively. The maximum magnitudes of strain energy density calculated using the total knee replacement models were less than 15% of the corresponding magnitudes from the intact bone model. The greatest difference was found to occur at the anterior distal corner of the femur, suggesting this location as the one most vulnerable to stress-shielding. Clinically observed bone loss after total knee replacement frequently occurs at this location. At the anterior distal corner, the calculated magnitudes for the two total knee replacement models were similar, suggesting that stress-shielding at this location was not reduced by limiting fixation only to the distal interface. Although the study corresponded to one loading condition and one geometry of the total knee replacement femoral component with the inherent limitations of model calculations, the results suggest a possible scenario for stress-shielding.

Bone Resorption↗
PubMed1996

Patients' perception of public, voluntary and private dispensaries in rural areas of Tanzania.

Eighty percent of rural dispensaries are run by the government and 19% by voluntary organisations that charge for some services. After the re-legalisation of the private health sector in 1991, private dispensaries are also emerging in villages. Privatisation is among the health reform policies of the country. Moreover, cost-sharing will be introduced at public dispensaries soon. Perception of 320 patients in the Coast Region of Tanzania on services delivered by the three health sectors has been investigated. Results show that patients are generally satisfied with the services and they would go back to the same dispensaries for treatment. Polydrug prescription was common in all sectors, while lack of prescribed drugs was a main complaint among public dispensaries patients. Voluntary dispensaries patients were less satisfied with long waiting time and with staff that did not give them enough information about the treatment. Currently, health service in public dispensaries is free but cost-sharing will be introduced soon. Most of voluntary and private dispensaries patients stated that the fees for service were moderate. The paper discusses the need for monitoring the implementation of cost sharing in public dispensaries to ensure equity in access to services by rural patients.

Adult↗
PubMed1995

Tensile stress-strain characteristics of the human meniscal material.

The nonlinear stress-strain characteristics of the human menisci were determined by uniaxial elongation tests performed on circumferential and radial specimens prepared from different regions, layers, and locations. The properties of the collagen fibers and the matrix were calculated using the test results along with the values of the volume fractions of the meniscal components. Regression analysis showed that only three parameters, the elastic modulus, the maximum strain, and the strain intersect, are sufficient to define the nonlinear stress-strain relation up to failure. For radial specimens, the layer had a significant effect (p < 0.01) on the elastic modulus and the maximum strain, but had no effect on the strain intersect and the maximum stress. For the same specimens, the region had a significant effect (p < 0.01) only on the strain intersect and the maximum stress. For circumferential specimens, analysis indicated no significant effect of either the region, the layer, or the location of the specimens on the material parameters defining the stress-strain relation.

Adult↗
PubMed1995

Protean manifestation of gastrointestinal tuberculosis: report on 130 patients.

Over the past 8 years, 820 patients with tuberculosis were seen at the Armed Forces Hospital, Riyadh, Kingdom of Saudi Arabia. A total of 292 of these patients (35.6%) had pulmonary tuberculosis, and 130 patients (15.8%) had alimentary tract tuberculosis, making this the second commonest site of involvement. In these 130 patients, the disease was located in the upper gastrointestinal tract in 11 patients (8.5%), small bowel 44 patients (33.8%), large bowel 29 patients (22.3%), peritoneum 40 patients (30.7%), and liver 19 patients (14.6%). The diagnosis in most patients was made by specimens from endoscopy or laparoscopy, or liver or surgical specimens. Gastrointestinal tuberculosis is not uncommon in developing countries, and its incidence is increasing in developed countries due to immigration and in patients with AIDS or those receiving immunosuppressive therapy. It can mimic any diseases affecting the gastrointestinal tract and may present with very different symptoms, so a high index of suspicion is required.

Adult↗
PubMed1995

Does health information alone help in equitable distribution of essential drug kits between health units at district level?

In Tanzania, the essential drugs programme (EDP) faces acute shortage of drugs brought about by a deteriorating economy and an expanding primary health care system. Many health units complain of shortages of drugs but no increase in the district allocation of EDP kits is foreseen. In the light of the aforementioned problem, a study was carried out in the Kisarawe district of Tanzania to discover, on behalf of the District Health Management Team (DHMT), the extent of the maldistribution with a view to reallocate the EDP kits among the health units on the basis of workload and catchment population. The relative workload of each health unit was estimated from the number of outpatient attendants and the catchment population estimates are based on a 1988 national census. An equitable distribution of EDP kits for each indicator was then developed by ranking the health units in order of workload and catchment population and dividing up the available number of EDP kits proportionately. Health units were categorised as either 'over-allocated', 'appropriately-allocated' or 'under-allocated' with EDP kits by comparing their actual drug supply with the equitable supply. The findings were presented to a meeting of the DHMT attended by the Regional Medical Officer and Ministry of Health officials. Despite being presented evidence of astounding inequity in drug distribution, there was a marked reluctance on the part of the DHMT to decide upon actions to redress some of the imbalance. In this study, we demonstrated that although data from the routine information system on essential drugs at peripheral health units provided sufficient information for managerial purposes, decision-making was delayed and limited. Several possible reasons for this are discussed.

Administrative Personnel↗
PubMed1994

Helicobacter pylori: incidence and comparison of three diagnostic methods in 196 Saudi patients with dyspepsia.

One hundred and ninety-six symptomatic Saudi patients with dyspepsia underwent gastroscopy, and multiple biopsies were taken from the antrum of the stomach for identification of Helicobacter pylori. Three methods were studied for diagnosis of Helicobacter pylori, including urease test, culture and histopathology. The commonest gastroscopic findings were gastritis in 82 patients (41.84%) and duodenal ulcer in 40 patients (20.41%). Among the 196 patients, Helicobacter pylori was identified by histopathology in 145 patients (73.98%), the urease test was positive in 126 patients (64.29%), and a positive culture was obtained in 102 patients (52.04%). These results show that there is a high incidence of Helicobacter infection among Saudi patients with peptic ulcer disease or non-ulcer dyspepsia. Helicobacter pylori identification was more successful by histopathology than by the urease test or culture.

Biopsy, Needle↗
PubMed1993

The return of life-threatening puerperal sepsis caused by group A streptococci.

A dramatic decline in the prevalence of serious puerperal infection caused by group A beta-hemolytic streptococci has been observed throughout most of the twentieth century, and it is currently a very uncommon cause of maternal morbidity and mortality. We report on two term pregnancies complicated by profound multisystem organ failure caused by group A streptococcal puerperal sepsis. This report serves to highlight the apparent return of serious group A streptococcal puerperal sepsis and to emphasize the clinical implications and sequelae attributable to an old yet virulent enemy.

Adult↗
PubMed1993

Design and development of an unconstrained dynamic knee simulator.

A dynamic knee simulator has been developed to allow in-vitro investigation of the mechanical response of the joint corresponding to dynamic functional activities, e.g., walking. In the simulator, the controlled inputs are the time-histories of three parameters of a given dynamic activity: the flexion angle, and the flexion/extension moment and tibial axial force components of the foot-to-floor reaction. A combination of stepping motors and electro-hydraulic actuators is used to apply to a knee specimen, simultaneously and independently, the specified load and/or displacement inputs while allowing unconstrained relative motion between the joint members. Satisfactory performance of the simulator has been established for walking gait conditions based on measurements on three fresh-frozen specimens.

Biomechanical Phenomena↗
PubMed1993

Pursuing better health care delivery at district level.

In the urban and rural districts of Tanzania's Dodoma Region a process was adopted for identifying and solving problems of health care delivery. In a single year, considerable improvements were secured in both teamwork and attitudes towards coping with managerial obstacles.

Adult↗
PubMed1993

Frequency of gastroesophageal reflux in patients with liver cirrhosis.

Twenty-five adult patients with liver cirrhosis, and another 30 patients with no liver disease but referred with symptoms suggestive of gastroesophageal reflux disease were selected at random. Twenty-four hour ambulatory intra-esophageal pH measurement and upper gastrointestinal endoscopy were carried out on all patients recruited. Applying the former test, 16 (64%) of the patients with liver cirrhosis have gastroesophageal reflux disease. This figure is comparable with the 70% (21/30) rate recorded in the group of dyspeptic patients clinically thought to have the disorder. A positive endoscopic diagnosis was much lower at 12% and 23%, respectively. No significant differences were observed among liver disease patients when they were subdivided in accordance with the etiology of liver cirrhosis and the grade of esophageal varices. We conclude that gastroesophageal reflux disease occurs at a high frequency (64%) in patients with liver cirrhosis and portal hypertension, irrespective of the etiology of cirrhosis and the grade of esophageal varices. It is therefore considered to be the main cause of esophagitis in these patients, and that it might play a role in initiating a variceal bleeding episode. The latter hypothesis needs further evaluation.

Adult↗
PubMed1992

Ligament tension pattern in the flexed knee in combined passive anterior translation and axial rotation.

Twenty-two fresh-frozen specimens were used to measure tensions generated in selected bands of the major ligaments of the flexed knee (40-90 degrees) when an axially prerotated tibia is subjected to passive anterior shear and when an anteriorly pretranslated tibia is subjected to passive axial torque. The tensions were measured using the buckle transducer attached to the anteromedial band of the anterior cruciate ligament [ACL (am)], the posterior fibers of the posterior cruciate ligament [PCL (pf)], the long fibers of the medial collateral ligament [MCL (lf)], and in the total lateral collateral ligament [LCL]. The knee specimens were subjected to the combined motions in a 6-df passive loading apparatus. The results indicated that the joint resistance to anterior translation increased markedly with internal prerotation and only marginally with external prerotation. This increase in joint resistance, however, was associated with a decrease in ACL function. It has been inferred that the posterior structures, capsular and meniscal, contribute significantly to joint resistance when the tibia is prerotated in either sense. For internal prerotation, the interference between the medial femoral condyle and the central tibial eminence was found to be an additional mechanism of resistance to anterior translation. Also, it has been found that although the ACL (am) tension increased with internal rotation in the normal case, it decreased with internal rotation in the presence of an anterior pretranslation. It is concluded that ACL response to combined joint motion cannot be ascertained by a simple summation of its responses to individual motions.

Adult↗