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Biomedical subjects

S A Ibrahim

Publications and source records attributed to S A Ibrahim.

At least 19 recordsLinked to original sources
PubMed1997

Contributions of Rocky Flats releases to the total plutonium in regional soils.

Total 239,240Pu and the 240Pu:239Pu atom ratio were measured in soil samples from around the Rocky Flats Environmental Technology Site (RFETS) during 1992-1994. Mass isotopic data provided a sensitive technique to resolve low levels of RFETS 239,240Pu superimposed on plutonium from global fallout. Concentrations of 239,240Pu within this sample set ranged from 1.1 Bq kg(-1) offsite to 57 Bq kg(-1) onsite, and the 240Pu:239Pu atom ratio increased from 0.055 onsite to 0.123 at approximately 19 km east of the RFETS boundary. The relationship between 24OPu:239Pu atom ratios and distance indicated that a measurable RFETS contribution may have extended to > or = 19 km offsite in the easterly direction. Although the RFETS contribution to total plutonium at the offsite locations ranged from 24-90%, the overall inventory was relatively small. Total inventory estimates, for one transect, based on 239,240Pu and from 240Pu:239Pu atom ratio measurements were not significantly different.

Colorado↗
PubMed1996

Comparative distribution of 241 Am and 239,240 Pu in soils around the Rocky Flats Environmental Technology Site.

The distribution and behavior of 241 Am and 239,240 Pu in soils from the buffer zone of the Rocky Flats Environmental Technology Site have been investigated. Concentrations of both radionuclides decreased at similar rates with soil depth. More than 80% of the total inventory of both contaminants was found in the upper 9 cm of the soils with over 50% of the inventory residing in the top 3 cm. Comparison with earlier studies indicate that the plutonium depth profile has not changed significantly over the last 25 y. The inventories of 241 Am and 239,240 Pu decreased with distance from the 903 Pad (a former waste storage site) according to a power function, and the plume extended mainly toward the east. The lateral movement of the two contaminants away from the 903 Pad was not significantly different. The median activity ratio of 241 Am: 239,240 Pu ranged from 17 to 19% and was independent of sampling location and soil depth. This observation provided further evidence that the movement of both contaminants is indistinguishable in the study area. Because of the strong correlation between the two radionuclides, 241 Am concentrations can then be used to infer 239,240 Pu by counting the 241 Am via gamma spectroscopy.

Americium↗
PubMed1995

Comparative study on brush border membranes prepared from rat and monkey small intestine by Ca2+ and Mg2+ precipitation.

Brush border membranes, prepared by Ca2+ or Mg2+ precipitation, from monkey or rat small intestine were compared for marker enzyme enrichment and lipid composition. Membranes prepared from rat intestine by Mg2+ precipitation were less pure in terms of their marker enzyme enrichment than Ca2+ precipitated membranes. Moreover, Mg2+ precipitated membranes were contaminated by basolateral membranes as evidenced by the enrichment of Na(+)-K+ ATPase. The content and composition of phospholipids were different in Mg2+ and Ca2+ precipitated membranes. The membranes prepared by the two methods from monkeys were identical in their marker enzyme enrichment and lipid composition and unlike those obtained from the rat, there was no basolateral membrane contamination.

Alkaline Phosphatase↗
PubMed1995

Plutonium concentrations in lichens of Rocky Flats environs.

Xanthoparmelia spp. lichens were used to study the spatial distribution of plutonium concentrations in nonvascular plants surrounding the Rocky Flats nuclear weapons facility with respect to distance, direction, age, and washing. Plutonium concentrations in lichens were inversely related to distance from the initial contamination site with a directional component which corroborated wind-borne transport as the primary means of dispersion. Ultrasonic washing and the relative age of the lichen proved to be significant only at p = 0.21 and p = 0.96, respectively. Isotopic ratios of 239,240Pu to 238Pu were highly variable at low activities but remained consistent at 62.6 for samples with high total plutonium activity. Correlation of Xanthoparmelia spp. lichen 239,240Pu concentrations to surface soil concentrations showed a direct relationship (r = 0.767; p < 0.001). The correlation was supported by soil retention studies which revealed a lichen soil content ranging from 11 to 18% on a dry mass basis with a possible particle size selectivity in the different concentration ratios adjacent to and away from the initial contamination site. Results suggest that further study into the in situ biomonitoring of surface soil by Xanthoparmelia spp. lichens is promising.

Colorado↗
PubMed1995

Normal values for lung function tests in Sudanese children.

Forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and peak expiratory flow rates (PEFR) were determined in 400 healthy Sudanese school children aged between seven and 12 years aiming to establish normal values of lung indices. Both Wright's and Mini Wright's Peak Flow Metres (PFM) were used to measure the PEFR. The results were analysed with respect to age, weight, standing and sitting heights and the correlation coefficients (r) were calculated. Among the variable used, standing height (H) showed the best correlation with PEFR (r = 0.97) and with FEV1 (r = 0.90). The scatter diagrams produced by plotting the values of each of the lung function indices against age, weight, or height were comparable. Readings obtained using Mini Wright's PFM were higher than those of the wright's by a mean of 18.0 and 16.0 litres for boys and girls, respectively, Prediction formulae for mean points have been produced with age and standing heights as independent variables. The indices of Sudanese children are similar to those of the Libyan, higher than those of the Nigerian and Indian and lower than of the European and American children.

Age Factors↗
PubMed1995

Lipid composition and membrane fluidity of monkey small intestinal brush border membrane: regional differences.

Brush border membrane vesicles (BBMV) isolated from various regions of monkey small intestine were compared for lipid composition, membrane fluidity and sodium-dependent D-glucose transport. Total phospholipid content was same in all regions whereas cholesterol content was high in duodenum and jejunum as compared to ileum resulting in higher cholesterol/phospholipid molar ratios. Regional differences in individual phospholipid subclasses and fatty acids in total lipids were also observed. Fluidity measurements showed that the membranes of duodenum and jejunum were less fluid than ileum. The change in BBMV fluidity appears to be due to alteration in cholesterol/phospholipid ratio and phospholipid composition. The sodium dependent D-glucose uptake was more in duodenum and jejunum as compared to ileum. These results suggest that there is a regional difference in the lipid composition and fluidity of BBMV in monkey small intestine which may influence their function.

Animals↗
PubMed1994

Factors associated with high risk of perinatal and neonatal mortality: an interim report on a prospective community-based study in rural Sudan.

In a community-based prospective study, 6275 deliveries resulting in 6084 livebirths, 150 stillbirths (SB) and 167 neonatal deaths (NND) were monitored over a period of 3 years. The risk of an unfavourable outcome (SB or NND) in multiple pregnancies was more than ninefold that of singletons. Teenage mothers and those over 34 years of age ran nearly twice the risk of having an unfavourable outcome of pregnancy compared with mothers aged 20-29 years. First pregnancy and grand-multiparity (greater than eight previous pregnancies) carried a similar risk of an unfavourable outcome compared with mothers with 1-4 previous pregnancies. The most serious risk factor was the adverse outcome of the previous pregnancy. Compared with mothers whose last outcome had resulted in a livebirth surviving at least 30 days, mothers with a previous SB had seven times the risk (adjusted for age and parity) of SB and more than twice the risk of NND in the current pregnancy. Maternal illiteracy was associated with significantly higher risk of NND, and this rate decreased with increasing years of education. Frequency of antenatal visits had a marginally significant effect on the SB rate. Socioeconomic factors, diet and iron supplementation during pregnancy did not seem to affect the outcome.

Educational Status↗
PubMed1994

Correlation of some biochemical parameters with clinical features of protein energy malnutrition.

The authors report on a study correlating the laboratory findings of children with protein energy malnutrition (PEM) with their clinical presentations. Forty-nine cases of marasmus, 17 of kwashiorkor and 28 of marasmic-kwashiorkor, as well as 20 controls, were studied and monitored in hospital. Fasting plasma samples obtained on days 2, 14 and 21 were analyzed for total proteins, albumin, triglycerides and cholesterol. Blood glucose and haemoglobin were also determined. The total plasma proteins and albumin were significantly lower in all the malnourished cases compared to the controls, with marked hypoproteinaemia among those cases with kwashiorkor. Plasma triglycerides were significantly lower in the malnourished group, when compared to controls. With dietary treatment, plasma triglycerides rose significantly accompanied with regression in liver size. Four out of the 17 children with kwashiorkor, had died; they had the lowest serum albumin concentrations of all the cases studied. The mean haemoglobin concentration of those who died was also significantly lower than that of the survivors.

Blood Glucose↗
PubMed1993

Effect of oxidant exposure on monkey intestinal brush-border membrane.

This study looks at the effect of oxidant exposure on changes in structural components and functional properties of monkey intestinal brush-border membrane vesicles (BBMV). These membranes were found resistant to iron-dependent lipid peroxidation as judged by measurement of various parameters such as formation of malonaldehyde (MDA) and conjugated diene and depletion of total arachidonic acid, tocopherol and membrane-associated protein thiol groups. Free radicals generated by thermal decomposition of 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP) which does not require iron, were capable of inducing lipid peroxidation in this membrane. Fluorescence polarisation studies used to assess the physical state of the membrane lipids after exposure to various free radical generating systems showed that ABAP could decrease the fluidity of BBMV whereas other systems had no effect. Exposure of BBMV to ABAP or cumene hydroperoxide decreased the glucose and amino acid transport. BBMV had a high content of nonesterified fatty acids as part of the total lipids and removal of these free fatty acids by treatment with fatty acid free albumin made the membranes susceptible to iron-dependent peroxidation. These studies suggest that intestinal epithelial cell membranes are resistant to iron-dependent lipid peroxidation due to the presence of membrane-associated free fatty acids. Possibly lipid peroxidation may play a less significant role in damage to these cells.

Amino Acids↗
PubMed1993

Treatment of dextran sulfate sodium-induced murine colitis by intracolonic cyclosporin.

The use of oral and intravenous cyclosporin represents a significant advance in the therapy of refractory inflammatory bowel diseases (IBD). However, oral administration of cyclosporin is fraught with improper delivery of cyclosporin to the colon for its topical action. Because of unpredictable metabolism by cytochrome P-450 IIIA, the targeted blood level for systemic effect is not reached at low doses. Furthermore, the doses that have been used for therapy of IBD have been shown to induce several adverse side effects. Thus, an alternate method of delivering cyclosporin to the colon is desirable. In this study, the effect of intracolonically administered cyclosporin was tested for its efficacy to heal mucosal erosions in dextran sulfate sodium (DSS)-induced colitis in mice. Both acute and chronic colitis was induced by feeding female Swiss-Webster mice with 5% DSS (30,000-40,000 mol wt) for five or seven days, respectively. Therapy was advocated prophylactically, prophylaxis plus therapy and therapeutically during the acute and chronic phase of the disease and therapeutically during the chronic phase of the disease. Intracolonic cyclosporin given prophylactically showed adverse effects by increasing the damage to the colonic mucosa. However, intracolonic cyclosporin given therapeutically in 2.5, 5, and 10 mg/kg after the induction of colitis resulted in dramatic responses in terms of reducing the disease activity and histologic scores, corroborated by complete histological resolution compared to oral cyclosporin given at identical doses. Intracolonic cyclosporin (5 mg/kg) was also very effective in reducing the chronic inflammation. The results of this study highlight the application of this animal model for therapeutic research. Furthermore, cyclosporin administered as an enema provides a new stratagem for the therapy of IBD because of its rapid onset of action at very low doses without the risk inherent in oral or systemic administration.

Acute Disease↗
PubMed1993

Studies on nonesterified fatty acids in rat intestinal cell membranes.

Lipid composition of total membrane fractions prepared from scraped rat intestinal mucosa and isolated epithelial cells were compared. Membranes prepared from mucosa had four times higher nonesterified fatty acids (NEFA) as compared to the epithelial cell membranes. Cholesterol and phospholipid contents were similar in both the membrane preparations but triglyceride content was high and di- and monoglyceride were low in epithelial cell membranes as compared to the mucosal membranes. Inclusion of p-bromophenacyl bromide, a phospholipase inhibitor, in the intestinal lumen wash solution and homogenizing buffer did not reduce the NEFA content of the scraped mucosal membranes whereas inclusion of diethyl p-nitrophenyl phosphate, a lipase inhibitor reduced it by 40%. These results suggest that NEFA are normal constituent of intestinal cell membranes.

Animals↗
PubMed1993

Modulation of monkey small intestinal brush border membrane D-glucose transport by nonesterified fatty acids.

Brush border membranes isolated from monkey intestinal mucosa was found to contain considerable amount of nonesterified fatty acids. Incubation of brush border membranes with fatty acid free albumin selectively removed the free fatty acids more than 80% without altering the level of phospholipids or cholesterol. The sodium dependent D-glucose transport was stimulated by the albumin treatment. Kinetic study showed that albumin treatment did not alter the apparent affinity (Km) of the transporter for glucose whereas the maximal velocity (Vmax) was increased significantly. The sodium dependent D-glucose transport was inhibited by the exogenously added unsaturated fatty acids. Saturated fatty acids and methyl esters of unsaturated fatty acids showed no inhibition. Based on these results, it may be concluded that free fatty acids inhibit the sodium dependent intestinal D-glucose transport either by directly interacting with the transport protein or by abolishing the sodium gradient.

Animals↗
PubMed1992

The role of the village midwife in detection of high risk pregnancies and newborns.

The preliminary findings of a prospective study of perinatal, neonatal and maternal mortality carried out in a rural community of Sudan are reported. Out of 6275 deliveries monitored over a period of 3 years, 150 stillbirths, 167 neonatal deaths and 27 maternal deaths were observed. An intervention program to upgrade the skills of the village midwives started in the middle of the second year. There was a 25% reduction in the risk of unfavorable outcome of pregnancy (i.e. stillbirth and neonatal death) in the third year relative to the first 2 years. Peer review of the 40 village midwives who took part in the study revealed their tremendous potentials in mobilization of mothers as well as participation in primary health care. Their role in detection of high risk pregnancies and newborns cannot be overemphasized.

Adolescent↗
PubMed1992

Maillard reaction-mediated molecular damage to extracellular matrix and other tissue proteins in diabetes, aging, and uremia.

Recent progress in structure elucidation of products of the advanced Maillard reaction now allows probing specifically for the role of this reaction in the pathogenesis of age- and diabetes-related complications. Pyrraline is a glucose-derived advanced glycation end product against which polyclonal and monoclonal antibodies have been raised. Immunohistochemical localization studies revealed that pyrraline is found predominantly in the sclerosed extracellular matrix of glomerular and arteriolar renal tissues from both diabetic and aged nondiabetic individuals. Pentosidine and carboxymethyllysine are Maillard end products derived from both glucose and ascorbate. In addition, pentosidine can be formed from several other sugars under oxidative conditions, and in vitro studies suggest that a common intermediate involving a pentose is a necessary precursor molecule. The highest levels of these advanced Maillard products are generally found in the extracellular matrix, but these products are also present in lens proteins and in proteins with a fast turnover such as plasma proteins. Diabetes, and especially uremia, greatly catalyzes pentosidine formation. Both conditions are characterized by accelerated cataractogenesis, atherosclerosis, and neuropathy, suggesting that molecular damage by advanced Maillard reaction products may be a common mechanism in their development.

Aging↗
PubMed1991

Structure and antimicrobial activity of some new azopyrazolone chelates of Ni(II) and Cu(II) acetates, sulfates, and nitrates.

Four coordinate Ni(II) and Cu(II) chelates formed by reaction of two azopyrazolone derivatives with metal sulfate, acetate, or nitrate are described. It is concluded that the ligands possess tautomeric equilibria and can coordinate to the metal ion as neutral or monobasic bidentates. The so-obtained complexes are characterized by elemental and thermal analyses, IR and electronic spectra, as well as conductivity measurements. A pseudo-tetrahedral polymeric structure is proposed for all the complexes in which the acetate, nitrate, or sulfate is attached to the metal ion in the bridging bidentate mode. It is observed that the chelates formed are more potent as antimicrobial agents than the free ligands.

Anti-Infective Agents↗
PubMed1991

Transfer of Eimeria apionodes from wood mice (Apodemus sylvaticus) to laboratory mice (Mus musculus).

Transfer of Eimeria apionodes from wood mice directly into untreated laboratory mice was unsuccessful but transfer into corticosteroid-treated animals produced an oocyst output, about 1000 times less than that observed from wood mice after a similar inoculum. Repeated passage through corticosteroid-treated laboratory mice resulted in a line adapted to survival in untreated animals. This line was compared with the parent strain maintained in wood mice and some features of the oocyst output patterns, notably the pre-patent period, appeared to be controlled by the host species. The oocyst production of each population was higher in the host species to which it was adapted than in the other host species (P less than 0.001). Once adapted to laboratory mice, the line produced insignificantly different levels of oocysts in corticosteroid-treated and untreated animals (P greater than 0.05).

Animals↗