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Biomedical subjects

M Darwish

Publications and source records attributed to M Darwish.

At least 19 recordsLinked to original sources
PubMed1996

The influence of alloy composition and casting procedure upon the corrosion behaviour of dental alloys: an in vitro study.

The influence of the composition and the casting process upon the electrochemical corrosion of a selection of palladium-based alloys and non-precious metal alloys has been investigated in vitro using an electrochemical method. No influence of the casting process upon the corrosion resistance was observed with palladium-based alloys. Changes in the crystallographic structure effected by the different composition of the alloys were found, the casting process did not cause significant effects. With nickel-chromium alloys rather low corrosion stabilities were observed.

Chemical Phenomena↗
PubMed1995

A comparative electrochemical in vitro evaluation of the corrosion behaviour of dental amalgams.

The electrochemical corrosion behaviour of 16 currently marketed amalgams for dental fillings was studied in vitro. Depending upon the type of amalgam and the treatment of the filling the electrochemical corrosion currents derived from cyclic voltammograms varied over several orders of magnitude. Their change as a function of time was also very different. Suggestions are made for a stability rating of the products based on the results obtained.

Corrosion↗
PubMed1995

Coxiella burnetii antibody prevalences among human populations in north-east Africa determined by enzyme immunoassay.

Retrospective serosurveys were conducted to determine the prevalence of antibody to phase-I Coxiella burnetii among humans in various locations of north-east Africa. Sera were tested by the enzyme immunoassay (EIA). Initially the EIA was compared with the standard indirect fluorescent antibody (IFA) method for the detection of antibody to C. burnetii. Results indicated that the EIA was slightly less sensitive (88%), but highly specific (94%) and less subjective than the IFA technique. EIA was subsequently adopted for estimating prevalences in the studied human populations. Data obtained by EIA indicated that the prevalence of C. burnetii antibody among adult Egyptian blood donors was 20% (n = 358) in the Suez Canal area, 16% (n = 501) in the Nile Valley and 10% (n = 427) in the Nile Delta. Among adult patients with acute, undifferentiated fever in Egypt, the prevalence was 28% (n = 50) of acute sera, with seroconversion in 12% of convalescent sera. Antibody to C. burnetii was detected by EIA in the sera of 25% (n = 71) of cattle workers in Egypt, 10% (n = 100) of housewives in Sudan, and 37% (n = 104) of adults in north-west Somalia. Following a fever outbreak affecting all ages in northern Sudan, IgG antibody to C. burnetii was present in 54% of the febrile persons (n = 185) and in 53% of afebrile persons (n = 186). IgM antibody to C. burnetii was demonstrated in 29% of the febrile persons and 15% of the afebrile persons. These results implicate C. burnetii as a possibly important and under-reported cause of human disease and undiagnosed fevers in north-east Africa.

Adult↗
PubMed1993

Community-based prevalence profile of arboviral, rickettsial, and Hantaan-like viral antibody in the Nile River Delta of Egypt.

To determine the current prevalence of antibody to arboviruses, rickettsiae, and hantaan-like viruses, a survey was carried out in the Nile River Valley of Egypt, one of the principal foci of the 1977-1978 Rift Valley fever (RVF) outbreak. Blood specimens were obtained from 915 persons representing 190 study households. Enzyme immunoassay testing showed that the overall prevalence of IgG antibody was 4% to sand fly fever Sicilian (SFS), 2% to sandfly fever Naples (SFN), 15% to RVF, 20% to West Nile, and 4% to Hantaan (HTN) viruses. Antibody was demonstrated among 32% of the same study subjects to Coxiella burnetii, 58% to Rickettsia typhi, and 32% to R. conorii. The prevalence of agent-specific antibody tended to increase with age. Particularly notable was the low prevalence of RVF infection in children born after the height of the RVF outbreak. No detectable antibodies were found in the population less than seven years of age and in only 3% of those 7-12 years old. In contrast, 26% of the study population 13-19 years old, who were young children and infants at the time of the outbreak, were found to have RVF antibodies, suggesting that the level of intensity associated with transmission decreased considerably following the documented 1977-1978 outbreak. Geometric mean titers (GMT) ranged from 139 for C. burnetii to 1,305 for RVF, and did not vary significantly by age, except for high titers for RVF in the 20-49-year-old age group. A significant upward trend in GMT was also noted when antibody was detected in the specimen for more than one phlebovirus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Prediction of netilmicin disposition in neonates.

Multiple regression analyses of data from 33 neonates who received netilmicin therapy showed that concurrent treatment with other drugs (Drg), creatinine clearance (CLcr), gestational age (GA), and an apgar score of less than 6 at 1 min (Agl') were significant determinants of netilmicin clearance. Apparent volume of distribution was significantly affected by postnatal age (PNA), gender, the presence of ascites and/or oedema (A/O), and whether or not the neonate was small for gestational age (SGA). The following formulae were obtained: [formula: see text] The regression formulae were shown to predict netilmicin plasma concentrations with good precision and a non-significant bias in a further 15 neonates studied prospectively.

Apgar Score↗
PubMed1992

Reliability and validity of self and proxy reporting of morbidity data: a case study from Beirut, Lebanon.

We compared the self-reported illnesses (heart disease, back pain, rheumatoid arthritis, hypertension, and pulmonary disease) and smoking histories of 100 cases and 100 controls matched for age and sex with reports of this information from proxy informants from the same household in two areas in the city of Beirut. In addition, both cases and controls were given physical examinations to evaluate the accuracy of the responses. The level of agreement between the responses of subjects and of their informants varied from one condition to the other. Heart disease had the highest level of agreement, with the proportion of agreement greater than 93% for the cases and the controls and having chi values of 0.79 and 1.0, respectively. The report of back pain exhibited the lowest level of agreement, with responses showing a proportion of agreement of 74% for the cases and 90% for the controls, with chi values of 0.49 and 0.50, respectively. In comparing the responses of subjects and proxy informants with the results of physical examinations, heart disease had the highest level of agreement (J index ranged from 0.69 to 0.84), and back pain had the lowest level of agreement (J index ranged 0.42 to 0.48). These results show that proxy informants are good respondents for members of the same household and that health interview surveys are accurate for data collection of well defined chronic conditions.

Adult↗
PubMed1990

Hepatitis B virus infection among immunocompromised patients in Egypt.

Several workers reported an increased susceptibility to hepatitis B virus (HBV) in immunosuppressed patients. A study was carried out on 4 groups of supposedly immunocompromised patients for hepatitis B surface antigen (HBsAg), and anti-HBs. The 4 groups of patients were suffering from: Leprosy, Bronchial asthma, Diabetes and hepatosplenic Schistosomiasis. Serum specimens were obtained from 137 patients representing the 4 groups and from a control group of 25 healthy individuals. All sera were tested by ELISA technique for HBsAg and anti-HBs. Results indicated that HBsAg carrier rate was 4% for the control healthy group, 7% for Bronchial asthma, 10% for Diabetes, 24% for Leprosy and 28% for hepatosplenic Schistosomiasis. On the other hand, the anti-HBs was 21% for the control group, 29% for Schistosomiasis, 55% and 58% for Diabetes and Bronchial asthma respectively and 74% for Leprosy. This study shows that immunosuppressed patients particularly those suffering from leprosy and hepatosplenic Schistosomiasis experience higher HBsAg carrier rate than the control group for the endemic hepatitis B (6-7 times higher for leprosy and Schistosomiasis). An important observation was the diminished anti-HBs rate in hepatosplenic Schistosomiasis patients, despite the highest HBsAg carrier rate they exhibited. This may be due to an immunological defect, resulting in an unsatisfactory antibody response and chronic hepatitis B antigenemia. In Egypt, where Schistosomiasis is prevalent (40-50%), the problems caused by hepatitis B infection are increased.

Asthma↗
PubMed1990

Rheumatic fever and rubella immunity.

Anti-rubella IgG titer was estimated in 106 children: sixty five had acute rheumatic fever and 41 had either a history of rheumatic fever or a definite rheumatic heart disease. Their ages ranged from 6 to 16 years old (11.4 +/- 2.7 years). Sixty two were females and 44 were males. They were compared with 35 control normal subjects of both sexes with no history of rheumatic affection, aged 5 to 14 years (10.2 +/- 3.6 years). The results obtained showed a significantly (p less than 0.001) higher rubella IgG titer level in the controls (1066.5 +/- 8.3) as compared to the rheumatic cases (521.2 +/- 3.0). No differences were found in the rubella antibody titer between cases of acute rheumatic fever and those with history of rheumatic fever or rheumatic heart disease, nor between males and females in either cases or controls. We suggested that the low rubella IgG levels encountered in the rheumatic cases, make them more susceptible to rheumatic fever affection. In other words, a high immunity level against rubella might also produce an immunity against an agent, possibly related to rubella virus, with a specific role in the development of rheumatic fever. Vaccination against rubella could be worth a trial, for prevention of rheumatic fever.

Adolescent↗
PubMed1989

Seroprevalence of murine typhus and fièvre boutonneuse in certain human populations in Egypt.

A study was conducted between 1984 and 1987 to determine the prevalence of Rickettsia typhi and Rickettsia conorii infections among humans residing in the Nile Delta, Suez Canal area and Nile Valley of Egypt. Serum specimens were obtained from garbage and rodent control workers, other unclassified occupational workers, and from patients with fever of undetermined aetiology. All sera were assayed for IgA + IgM + IgG (IgAMG) antibody mixture and if positive, reassayed for specific IgM antibody to rickettsia by the indirect fluorescent antibody technique. R. typhi antibody was found in 19% (33/178) of the garbage collectors, whereas only 1% (2/178) had demonstrable antibody to R. conorii. Among those with other occupations, R. typhi antibody was detected in 0.7% (2/295) and none had R. conorii antibody. The antibody prevalence rate for R. typhi among patients with febrile illness ranged from 25 to 41%, and from 2 to 15% for R. conorii, at three different locations in Egypt. In addition, IgM antibody to R. typhi was demonstrated in some patients showing symptoms compatible with rickettsial disease and in some patients who seroconverted, indicating that R. typhi was the cause of illness among some of these patients. These findings support previous observations that R. typhi and R. conorii are the causes of human rickettsial disease in Egypt, and that humans are commonly infected with R. typhi.

Adult↗
PubMed1987

Alterations in catecholamine levels and turnover in discrete brain areas after food deprivation.

The present study determined the levels and turnover of norepinephrine (NE), epinephrine (EPI) and dopamine (DA) in discrete brain areas of rats after 48 hr food deprivation. The steady-state levels of NE, EPI and DA in saline-treated food-deprived rats, relative to satiated rats, remained basically unchanged. However, 48 hr deprivation caused a site-selective potentiation, specifically in the hypothalamic paraventricular nucleus, in the depletion of NE after alpha-methyl-p-tyrosine injection (IP, 200 mg/kg), indicating an increase in NE turnover. While changes in EPI turnover could not be demonstrated, an apparent increase in DA turnover was detected in the perifornical lateral hypothalamus and anterior hypothalamic nucleus after deprivation, while decreased DA turnover was seen in the hypothalamic dorsomedial nucleus and caudate nucleus. These results may reflect specific functions of hypothalamic catecholamines in control of food intake.

Animals↗
PubMed1982

Synthesis and biological investigations of some 5H-1,3,4-oxadiazolo[3,2-a]pyrimidin-5-ones.

The synthesis of some substituted 7-hydroxy-5H-1,3,4-oxadiazolo [3,2-a]pyrimidin-5-ones, a class of bicyclics with unexplored pharmacotoxicological properties, is described. Reacting the 2-phenyl derivative with bis(2,4,5-trichlorophenyl)benzylmalonate afforded a linear pyrano-oxadiazolopyrimidinedione. The assigned structures were verified by IR, 1H-NMR, and mass spectral studies. Six compounds of the series were screened for in vitro antibacterial and antifungal activities. The effect of four compounds on alkaline phosphatase enzyme was also examined.

Alkaline Phosphatase↗