Biomedical subjects

S A Ibrahim

Publications and source records attributed to S A Ibrahim.

At least 37 records · Page 2Linked to original sources

PubMed2000

AAS and spectrophotometric determination of propranolol HCl and metoprolol tartrate.

Two simple and accurate spectrophotometric methods are described for the determination of propranolol hydrochloride (I) and metoprolol tartrate (II). The methods are based on the reaction of each drug as a secondary amine: (a) with carbon disulphide, the formed complex extracted into iso-butyl methyl ketone (IBMK) after chelation with Cu(II) ions at pH 7.5, followed by measuring the absorbance at 435.4 nm or indirectly for the drug by flame atomic absorption spectrophotometry (AAS). The calibration graph is linear up to 40 and 60 microg ml(-1) with apparent molar absorptivities of 6.89 x 10(3) and 1.08 x 104 l mol(-1) cm(-1) and correlation coefficients of 0.9994 and 0.9995 for propranolol and metoprolol, respectively; (b) with pi-acceptors, tetracyanoethylene (TCNE), or chloranilic acid (CLA) to give highly coloured complex species. The coloured products are quantitated spectrophotometrically at 415 or 510 nm for the two drugs with TCNE and CLA, respectively, and obey Beer's Law with RSD less than 2.0. The methods were applied to the determination of these drugs in pharmaceutical preparation without interferences.

Adrenergic beta-Antagonists↗

PubMed2000

Synthesis, X-ray powder structure, and magnetic properties of the new, weak ferromagnet iron(II) phenylphosphonate.

A new molecule-based weak ferromagnet of formula Fe[C6H5PO3].H2O was synthesized. It was characterized by thermogravimetric analysis and UV-visible and infrared spectroscopy, and the magnetic properties were studied using a superconducting quantum interference device magnetometer. The crystal structure of the compound was determined "ab initio" from X-ray powder diffraction data and refined by the Rietveld method. The crystals of Fe[C6H5PO3].H2O are orthorhombic, space group Pmn2(1), with a = 5.668(8) A, b = 14.453(2) A, c = 4.893(7) A, and Z = 2. The title compound is isostructural with the previously reported lamellar M[C6H5PO3].H2O, M = Mn(II), Zn(II), and Cd(II). The inorganic layers are made of Fe(II) ions octahedrally coordinated by five phosphonate oxygen atoms and one from oxygen of the water molecule. These layers are then separated by bilayers of the phenyl groups, and van der Waals contacts are established between them. The refinement has shown that the phenyl rings are disordered in the lattice. The oxidation state of the metal ion is +2, and the electronic configuration is d6 (S = 2) high-spin, as determined from dc magnetic susceptibility measurements from 150 K to room temperature. Below 100 K, the magnetic moment of Fe[C6H5PO3].H2O rises rapidly to a maximum at TN = 21.5 K, and then it decreases again. The peak at TN is associated with the 3D antiferromagnetic long-range ordering. Below the critical temperature, the title compound behaves as a "weak" ferromagnet, which represents the third type of magnetic materials characterized by having a finite zero-field magnetization, ferromagnets and ferrimagnets being the other two types. The large coercive field (i.e., 6400 G) observed in the hysteresis loop at T = 10 K is rare in molecule-based materials; it can be ascribed to a pronounced spin-orbit coupling for the 5T2g ground state of the Fe(II) ion in the octahedral environment.

Journal Article↗

PubMed2000

Racial differences in the utilization of oral anticoagulant therapy in heart failure: a study of elderly hospitalized patients.

To assess racial differences in the use of oral anticoagulant therapy for patients with heart failure, we conducted a cohort study of 30 hospitals in northeast Ohio. For 12,911 Medicare enrollees consecutively admitted in 1992 through 1994 with heart failure, crude and adjusted odds of being on oral anticoagulation were determined. The crude and adjusted odds of being African Americans on oral anticoagulant therapy relative to whites were 0.57 (95% confidence interval 0.47-0.69) and 0.55 (95% confidence interval 0. 45-0.67), respectively. African-Americans with heart failure were much less likely than whites to receive oral anticoagulant therapy, even after adjusting for other variables associated with anticoagulant use.

Administration, Oral↗

PubMed2000

Underutilization of oral anticoagulant therapy for stroke prevention in elderly patients with heart failure.

BACKGROUND: Oral anticoagulant therapy is the most effective prophylaxis against stroke in atrial fibrillation. Relatively few studies have examined the use of oral anticoagulant therapy for stroke prevention in a large cohort of elderly patients with heart failure. To examine the use of stroke prevention therapy, we studied elderly patients with heart failure admitted to 30 hospitals in northeast Ohio between 1992 and 1994. METHODS AND RESULTS: The sample consisted of 12,911 Medicare-insured patients > or =65 years of age who were consecutively admitted with a principal diagnosis of heart failure between 1992 and 1994. Baseline demographic and clinical characteristics for patients with the diagnosis of atrial fibrillation were calculated. Bivariate associations between receiving anticoagulant therapy and select demographic and clinical variables were calculated. In our cohort of patients with heart failure, 2093 had atrial fibrillation (16%). Only 414 (20%) of the patients with atrial fibrillation received oral anticoagulant therapy. Older age and history of gastrointestinal bleeding were significantly negatively associated with receiving oral anticoagulant therapy. History of stroke or transient ischemic attack was positively associated with receiving oral anticoagulant therapy. CONCLUSIONS: Atrial fibrillation is common in older patients with heart failure; oral anticoagulant therapy for stroke prevention, which has been shown to be effective, is underutilized in this patient population.

Administration, Oral↗

PubMed2000

Serological and virological characterization of clinically diagnosed cases of measles in suburban Khartoum.

Measles continues to be a major childhood disease in terms of global morbidity and mortality. In the main areas of its endemicity the only available means of diagnosis are based on clinical criteria: the presence of a maculopapular rash and fever accompanied by cough, coryza, and/or conjunctivitis. We have studied 38 clinically diagnosed cases of measles in Khartoum, Sudan, by means of serology, reverse transcriptase PCR (RT-PCR) on throat swabs and virus isolation from lymphocytes. On the basis of serology, 28 patients were diagnosed as having an acute measles virus (MV) infection, while in 10 cases the clinical symptoms proved to have other causes. It was shown that in cases with low serum immunoglobulin M (IgM) levels, an additional measurement of IgG or virus-neutralizing antibodies was necessary to discriminate between patients with an acute MV infection sampled during an early stage of the disease and patients who had experienced an MV infection in the more distant past. The serological laboratory diagnosis was validated by an MV-specific RT-PCR: for all confirmed measles cases tested a fragment of the correct size which hybridized with a third MV-specific primer could be amplified, while all serologically negative cases were also RT-PCR negative. MV could be isolated from 17 out of 23 of the serologically confirmed cases, demonstrating that virus isolation is less reliable as a diagnostic tool than serology or RT-PCR. This study stresses the urgent need for a rapid diagnostic field test for measles.

Adolescent↗

PubMed2000

Use of chemical mutagenesis for the isolation of food grade beta-galactosidase overproducing mutants of bifidobacteria, lactobacilli and Streptococcus thermophilus.

A classical chemical mutagenesis protocol was evaluated for increasing beta-galactosidase production by probiotic bacteria to improve their potential to treat symptoms of lactose malabsorption in humans. Two Bifidobacterium species (B. breve and B. longum) and one strain each of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus were tested by a single exposure to two chemical mutagens, ethyl methanesulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). To screen for beta-galactosidase (beta-gal) overproducing mutants, optimized EMS and MNNG mutant pots for each strain were plated on BHI agar containing 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal). Colonies that exhibited a blue color were selected for quantitative beta-gal activities using the o-nitrophenyl-beta-galactoside (ONPG) assay. Seventy-five mutants were obtained out of more than 2 million colonies screened and showed increased beta-galactosidase activities compared with the wild-type strains. EMS gave a higher frequency of beta-gal overproducing mutants than MNNG for three of the four strains, S. thermophilus, B. breve, and B. longum, whereas the frequency of L. delbrueckii ssp. bulgaricus beta-gal mutants was similar with both mutagens. The highest beta-gal increases, when induced during growth in lactose, for mutants of each culture were 137% for L. delbrueckii ssp. bulgaricus; 104% for S. thermophilus; 70% for B. breve; and 222% for B. longum mutants. This food-grade classical approach has the ability to moderately increase beta-gal concentrations in probiotic cultures to improve their potential for treating the symptoms of lactose malabsorption in humans.

Bifidobacterium↗

PubMed1999

Racial variation in the use of do-not-resuscitate orders.

OBJECTIVE: To compare the use of do-not-resuscitate (DNR) orders in African-American and white patients using a large, multisite, community-based sample. MEASUREMENTS: Our sample included 90,821 consecutive admissions to 30 hospitals in a large metropolitan region with six nonsurgical conditions from 1993 through 1995. Demographic and clinical data were abstracted from medical records. Admission severity of illness was measured using multivariate risk-adjustment models with excellent discrimination (receiver-operating characteristic curve areas, 0.82-0.88). Multiple logistic regression analysis was used to determine the independent association between race and use of DNR orders, adjusting for age, admission severity, and other covariates. MAIN RESULTS: In all patients, the rate of DNR orders was lower in African Americans than whites (9% vs 18%; p <.001). Rates of orders were also lower ( p <. 001) among African Americans in analyses stratified by age, gender, diagnosis, severity of illness, and in-hospital death. After adjusting for severity and other important covariates, the odds of a DNR order remained lower ( p <.001) for African-Americans relative to whites for all diagnoses, ranging from 0.38 for obstructive airway disease to 0.71 for gastrointestinal hemorrhage. Results were similar in analyses limited to orders written by the first, second, or seventh hospital day. Finally, among patients with DNR orders, African Americans were less likely to have orders written on the first hospital day and more likely to have orders written on subsequent days. CONCLUSIONS: The use of DNR orders was substantially lower in African Americans than in whites, even after adjusting for severity of illness and other covariates. Identification of factors underlying such differences will improve our understanding of the degree to which expectations for care differ in African American and white patients.

Adult↗

PubMed1999

Comparison of 241Am, (239,240)Pu and 137Cs concentrations in soil around rocky flats.

Gamma spectroscopy measurements were used to estimate concentrations of 241Am and 137Cs in soil profiles to depths of 21 cm at on-site and off-site locations around the Rocky Flats Environmental Technology Site and at regional background locations east of the Front Range between Colorado's borders with New Mexico and Wyoming. Concentrations of these radionuclides were compared with concentrations of (239,240)Pu in the same samples. Concentrations of 241Am in soil from depths of 0 to 3 cm decreased in an easterly direction from more than 5.3 kBq kg(-1) near the 903 pad to background levels of 1.3 Bq kg(-1) 5 to 7 km away at a rate that was nearly proportional to the inverse square of distance. Deposits of 137Cs were ubiquitous, averaging 0.12 kBq kg(-1) in soil from depths of 0 to 3 cm, but were unevenly distributed around Rocky Flats and the regional background locations. Deviations from the uniform exponential rate at which soil concentrations of 137Cs typically decreased with depth, -0.25 cm(-1) at undisturbed sites, enabled us to determine that about 10% of our sampling sites had been disturbed by erosion, tillage, or other factors. The mean rate at which (239,240)Pu decreased with depth was about the same, -0.23 cm(-1), throughout the study area. Soil concentrations of 241Am decreased with depth at a similar mean rate of -0.22 cm(-1) at locations close to the 903 pad where measurements were robust. Ratios between 241Am or (239,240)Pu and 137Cs proved more useful for delineating the extent and pattern of contamination from Rocky Flats than did activity concentrations in soil.

Americium↗

PubMed1999

Plutonium excretion in urine of residents living near the Rocky Flats Environmental Technology Site.

An assessment of current levels of 239Pu in individuals living near the Rocky Flats Environmental Technology Site was conducted. Long-term residents of areas adjacent to the Site, as well as people living well beyond any expected influence of the site, provided urine samples, which were analyzed by fission track analysis for the levels of 239Pu. The Rocky Flats Environmental Technology Site vicinity participants were selected for maximum possible exposure to environmental plutonium by virtue of residence location, length of residence, age, and outdoor lifestyle. The mean 239Pu excretion rate in urine estimated for the entire Rocky Flats group was 1.1 microBq d(-1), in contrast to that estimated for the background group (0.85 microBq d(-1)). The estimated median 239Pu excretion rate for the Rocky Flats group was 1.1 microBq d(-1), compared to 0.54 microBq d(-1) for the background group. Both parametric and non-parametric tests indicated that these differences were not statistically significant (alpha = 0.05). Measured levels of 239Pu in urine from the Rocky Flats group were low and well within the range of reported "background" values, indicating small doses and low health risks. The fission track analysis technique may not be sufficiently accurate or precise to allow definitive comparisons between two groups of subjects with near-background levels of 239Pu in urine.

Adult↗

PubMed1999

Spatial variations in natural background radiation: absorbed dose rates in air in Colorado.

Large and small-scale spatial variations in natural ambient background radiation dose rates in Colorado were investigated at 1,150 specific locations with particular attention to 40 of the more populated areas along the Front Range of the Rocky Mountains. Total dose rates (including cosmic and terrestrial components) in Front Range communities below 2,000 m elevation averaged 135 nGy h(-1). Terrestrial dose rates had a coefficient of variation of 17%. Communities above 2,000 m had a mean total dose rate of 196 nGy h(-1), and a terrestrial dose rate coefficient of variation of 17%. Across all Front Range communities, the coefficient of variation for terrestrial dose rates was 22%. Within individual communities, coefficient of variation values for terrestrial dose rates ranged from 3 to 21%. Smaller-scale spatial variability (to within a few meters) was relatively small (coefficient of variation values generally ranged from 3 to 7%). A significant linear relationship (r2 = 0.83) between the size of area surveyed (km2) and coefficient of variation value for terrestrial dose rates was found. West of the Continental Divide, the terrestrial component accounted for roughly 60% of total measured dose rates, while east of the Continental Divide, where enriched granitic source rocks and associated soils are prevalent, the terrestrial component generally accounted for two-thirds or more of total dose rates.

Air Pollutants, Radioactive↗

PubMed1999

Primary repair of the cruciate and collateral ligaments after traumatic dislocation of the knee.

The management of traumatic dislocation of the knee in 40 patients (41 knees) with a mean age of 26.3 years is described. They were treated by primary repair and reconstruction with autologous grafting of the anterior (ACL) and posterior cruciate ligaments (PCL) and repair injuries to the collateral ligament and soft-tissue. The ACL and PCL were reconstructed using the patellar tendon and the gracilis and semitendinosus tendons, respectively. Early mobilisation using a continuous-passive-movement machine and active exercises was started on the second day after operation. At a mean follow-up of 39 months no patient reported 'giving way' and all except one had good range of movement. Of the 41 knees, 21 were rated as excellent, 15 good, four fair and one poor. Early reconstruction of the cruciate ligaments and primary repair of the collateral ligaments followed by an aggressive rehabilitation programme are recommended for these young, active patients.

Adolescent↗

PubMed1998

Epstein-Barr virus, human papillomavirus, and flow cytometric cell cycle kinetics in nasopharyngeal carcinoma and inverted papilloma among Egyptian patients.

It is widely accepted that the Epstein-Barr virus is etiologically associated with the development of nasopharyngeal carcinoma. The human papillomavirus is also associated with inverted papilloma. We used the polymerase chain reaction technique to detect both viruses in both types of tumors. Flow cytometry was also used to study the DNA pattern and proliferative behavior of the tumors in relation to the viruses. EBV was detected in 13/20 (65%) of NPC specimens, and in none of IP (n = 10) or control specimens (n = 10). This indicates the contribution of EBV as an etiologic factor in NPC. Five cases of NPC (25%) were positive for HPV 16, two of them were EBV positive. Four HPV 16 positive cases were found among cases with inverted papilloma, but none among the control cases. Flow cytometry revealed that all NPC, IP, and control samples were diploid except one aneuploid NPC sample. Proliferative capacity (PC) of primary tumors was predictive of tumor recurrence in NPC. Using 13.6% as a cut-off point for PC, we were able to discriminate between high risk and low risk groups with 100% sensitivity and 86% specificity. PC can be used as a baseline prognostic parameter in NPC, making it possible to modify courses of treatment in an attempt to inhibit tumor recurrence.

Adolescent↗

PubMed1998

Agglutination behavior of mesophilic starter cultures as a function of proteolysis.

Seven mesophilic starter cultures were grown separately in sterilized skim milk for 8 h at 25 degrees C. At the end of the incubation period, samples were analyzed for agglutination behavior by using microscopic examination. Samples were also assayed for proteolytic activity by the spectrophotometric o-phthaldialdehyde (OPA) and trinitrobenzenesulfonic acid (TNBS) methods. This experiment was replicated three times in a randomized block design. Microscopic examination showed that some cultures existed as single cells, diplococci, or short chains; other cultures tended to form long chains. Short-chain-forming cultures had high proteolytic activities, whereas long-chain-forming cultures had low proteolytic activities as measured by the TNBS and OPA methods. Proteolysis measured by both methods ranked starter cultures in the same order (R2 = 0.82). Low detectability values (obtained by dividing the standard error of the sample estimate for each method by its slope ratio) for OPA and TNBS methods indicated that the two assays do not differ significantly (P > 0.05).

Agglutination↗

PubMed1997

Seasonal variations in semen quality of local and crossbred rams raised in the United Arab Emirates.

A total number of 900 semen ejaculates were collected by means of artificial vagina from 10 rams (five local and five crossbreed 'local x chios'). Each ram was scheduled for semen collection three times per week at equal intervals for approximately two months in each season. At each collection, two separate successive ejaculates were obtained. Semen ejaculates were tested for volume, pH, mass motility, methylene blue reduction time (MBRT) and sperm-cell concentration per milliliter. Sex drive of rams was estimated by measuring the reaction time (RT). The time from the first to the second ejaculate was also recorded (TBE). Data of the two breeds show that the overall means for seminal attributes were 0.75 ml, 6.82, 4.2, 216.1 s and 5102.26 x 10(6) sperm/ml, respectively. In both breeds the overall means for RT and TBE were 43.7 and 152.3 s, respectively. Excluding ejaculate volume and MBRT, breed of ram was without significant effect on the investigated seminal characters, and sex drive parameters. Semen of the second ejaculate was significantly (P < 0.01) less in volume, greater in motility, closer to neutrality, less in sperm-cell concentration. MBRT of the two ejaculates differed nonsignificantly. However, characteristics of the second ejaculate fell within the normal range of high quality semen. Although the tested rams are continuous breeding animals, yet seasonal variations in semen characteristics were observed. The best-quality semen occurred in winter (volume, 0.77 ml; pH, 6.95; motility, 4.53; MBRT, 3.24 min. and sperm concentration, 4932.72 x 10(6)/ml). According to the known indices of semen quality of the ram, semen of the other seasons is judged to be of good quality. The mean RT for both breeds was less than one minute. Breed effect on RT and BET was insignificant. Season of the year exerted a significant (P < 0.01) effect on RT. The shortest time was recorded in summer, whereas the longest one was that of autumn. This indicates that the high ambient temperature of summer, prevailing in this locality, did not decrease the sexual activity of the tested rams.

Animals↗

PubMed1997

Phospholipase D activity in the intestinal mitochondria: activation by oxygen free radicals.

A prominent feature of cell damage caused by oxidative stress is morphological and functional changes in the mitochondria. The present study looked at the effect of free radical exposure on intestinal mitochondrial lipids. Free radical exposure did not alter neutral lipids, but among the phospholipids, phosphatidylethanolamine (PE) content was decreased on exposure to superoxide anion, generated by xanthine-xanthine oxidase or menadione with a concomitant increase in the level of phosphatidic acid (PA), suggesting activation of phospholipase D (PLD). This enzyme did not show transphosphatidylation activity in the presence of ethanol or butanol, and the product formed was phosphatidic acid (PA). This was confirmed by separation of reaction products by HPLC. This alteration in mitochondrial phospholipid was abolished by the presence of superoxide dismutase. Exposure to H2O2 did not have any significant effect. Activation of PLD by free radicals was further confirmed by quantitation of ethanolamine released from PE. Absence of any change in the content of lysophospholipid or diglyceride following exposure of mitochondria to superoxide ruled out the involvement of phospholipase A2 or C in the altered lipid composition. Moreover, inclusion of phospholipase A2 inhibitors, chlorpromazine, or p-bromophenacyl bromide did not prevent the generation of PA on exposure to free radicals. These findings suggest that superoxide anion stimulates intestinal mitochondrial PLD resulting in PE degradation and PA formation. These alterations in mitochondrial lipids may play a role in causing the functional alteration seen in oxidative stress.

Animals↗

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↗

PubMed1997

A three-dimensional spatial model of plutonium in soil near Rocky Flats, Colorado.

The horizontal and depth distribution of plutonium was measured in soil east of the Rocky Flats Environmental Technology Site (formerly the Rocky Flats Plant) near Denver, Colorado, during 1992-1994. The study area was centered on the eastern plume of plutonium contamination and included transects extending from 0.2 km east of the primary origin of the contamination (the 903 Pad) to distances of up to 19 km northeast, east, southeast and south-southeast of the 903 Pad. Soil was collected in 3 cm layers down to 21 cm at exponentially increasing distances along the four transects. Plutonium concentrations decreased rapidly with depth, distance from the 903 Pad, and angle from due east. Depth distributions were independent of distance and angle from the 903 Pad, and our profile model can be used to adjust to a common basis, historical measurements made from sampling to different depths. Based on a total of approximately 1,400 independent measurements, mathematical functions were developed to describe the distance, directional, and depth relationships. These equations, combined with soil density and rock measurements, provided a new method to estimate the plutonium concentration or total deposition per unit area anywhere within the study area. Total deposition per unit area measurements at 50 sites provided an independent test of the model's predictive accuracy. Sampling coefficients of variation based on replicate samples at the main sampling locations averaged 33%, but ranged from 12 to 98%. The analytical measurement coefficient of variation averaged 8%. Mean 0-3 cm soil concentrations of (239,240)Pu among 10 Front Range "background" and 11 community locations near Rocky Flats were 2.1 and 2.3 Bq kg(-1), respectively.

Plutonium↗

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↗