Search PubMed⌕ Search

Biomedical subjects

A A Mahmoud

Publications and source records attributed to A A Mahmoud.

At least 19 recordsLinked to original sources
PubMed1999

Increased levels of soluble interleukin-4 receptor in the sera of patients with visceral leishmaniasis.

Kenyan subjects with visceral leishmaniasis were examined for evidence of increased production of soluble interleukin-4 receptor (sIL-4R). Soluble IL-4R regulates the bioactivity of IL-4, a cytokine important in mediating progressive forms of leishmaniasis. Persons with visceral leishmaniasis sustained 8- to 10-fold more circulating sIL-4R compared with Papua New Guinea residents with documented filariasis or uninfected Kenyan and North American subjects. Soluble IL-2R concentrations were elevated nonspecifically in both visceral leishmaniasis and filariasis patients. These findings are significant given that IL-4 induces sIL-4R in mice, and treatment with recombinant sIL-4R cures progressive murine leishmaniasis dependent on IL-4 bioactivity. Further studies are indicated to determine whether the immunologic detection of IL-4 produced in human visceral leishmaniasis is obscured because of sequestration by soluble receptor and whether the production of sIL-4R is relevant to the pathogenesis of visceral leishmaniasis.

Animals↗
PubMed1997

Mice with a targeted deletion of the IgE gene have increased worm burdens and reduced granulomatous inflammation following primary infection with Schistosoma mansoni.

Although IgE has been considered to play an essential role in host defense against parasitic helminth infections such as Schistosoma mansoni, in vivo evidence of a protective function of IgE in infected mice is lacking. In the present study, mice with a null mutation of the C epsilon gene, and thus incapable of making IgE (IgE deficient), were infected by S. mansoni cercariae percutaneously. In two independent experiments, IgE-deficient mice were significantly more susceptible to primary infection, developing worm burdens twofold greater than those of wild-type mice (p < 0.001). In contrast, resistance to challenge infection following three immunizations with irradiated cercariae was similar in the two groups. The percentage of reduction in worm burdens in immunized IgE-deficient animals compared with unimmunized mice was 50%; immunized wild-type mice had a reduction of 55% compared with the baseline parasite count. Levels of parasite-specific IgG1 were more than twofold lower in IgE-deficient mice after primary infection (p = 0.005), whereas no significant difference was observed in the IgG1 response of animals previously immunized with irradiated cercariae. IgE-deficient animals also developed significantly smaller granulomas (by 37-40%) around schistosome eggs deposited in their livers compared with wild-type animals (p < 0.001). The spleens of IgE-deficient mice contained significantly more Ag-specific IL-4-secreting cells following primary infection. These data show that IgE participates in parasite elimination in primary infection with S. mansoni and in the generation of humoral immunity and cytokine responses to the parasite.

Animals↗
PubMed1997

Expression of glutathione S-transferase activity and glutathione content in squamous cell carcinoma of bladder associated with schistosomiasis in a population in Egypt.

The present study was designed to describe the expression of the glutathione S-transferase/glutathione system in squamous cell carcinoma of the bladder in a population in Egypt. The glutathione-S transferase activity was significantly higher in bladder cancer specimens (n = 40) in comparison with schistosomiasis cystitis tissue (n = 42) (4-fold, p = 1 x 10(-12)) and with healthy control samples (n = 9) (10-fold, p = 1 x 10(-6)). The glutathione content was also significantly higher in bladder cancer than in cystitis tissue (2-fold, p = 8 x 10(-6)) and in control samples (6-fold, 8 x 10(-6)). When control mucosa and cystitis samples were compared, 2-fold increased values were obtained for glutathione-S transferase (p = 4 x 10(-3)) and glutathione (p = 1 x 10(-3)) in schistosomiasis bladder tissue. Results describe an over-expression of glutathione-S transferase and glutathione levels in squamous cell carcinoma of the bladder, and indicate a possible role in chemoresistance to pharmacological therapy.

Adult↗
PubMed1995

Tropical medicine. Current problems and possible solutions.

The health of the people in tropical and subtropical countries is compromised because of multiple factors including demography, economics, and particularly an ever-increasing burden of illness from infections and parasitic diseases. At the turn of the century, malaria, schistosomiasis, and tuberculosis are three major challenges that the majority of the world population is facing with few effective chemotherapeutic or immunologic tools. Furthermore, the ever-increasing threat of emerging infections is taxing our surveillance and detection procedures. The modern biomedical revolution promises a better outcome if a global effort in investing in health is effectively launched.

Age Factors↗
PubMed1993

New sesquiterpene alpha-methylene lactones from the Egyptian plant Jasonia candicans.

Extracts of the plant Jasonia candicans possess antimicrobial activity. ET2O/MeOH extracts were subjected to liquid chromatography, and several sesquiterpenes were isolated and identified including the known compounds confertin [1], 4,11(13)-eudesmadien-12-oic acid [2], and 11-eudesmen-4-ol [3]. Two new diol alpha-methylene lactone antimicrobial agents were identified from nmr and mass spectral data and X-ray crystallography as (4 alpha, 5 alpha, 8 beta, 10 beta)-4,10-dihydroxy-1,11(13)-guaidien-12,8-olide [4] and (4 alpha, 5 alpha, 8 beta, 10 alpha)-4,10-dihydroxyl-1,11 (13)-guaidien-12,8-olide[5], which differ in stereochemistry at the C-10 tertiary alcohol center.

Lactones↗
PubMed1993

Knowledge and practices of pregnant women in relation to the intake of drugs during pregnancy.

The present study was done to assess Knowledge and practices of expectant women regarding drug intake during pregnancy. To achieve this aim, a simple random sample of 400 pregnant women during their last trimester of pregnancy were selected. A specially designed interview schedule was developed and used to collect the necessary data about the study subjects. The interview schedule consisted of four main parts to cover the following: 1. General characteristics of the sample. 2. Obstetrical characteristics of the sample 3. Knowledge about drug intake during pregnancy. 4. Practices of the study subjects in relation to drug intake during pregnancy. 5. Factors affecting their knowledge regarding drug intake during pregnancy. The main findings of the study were: 1. In general, the study sample lacked the essential knowledge regarding drug intake during pregnancy especially in relation to the risk time for taking drugs in which nearly one-fifth of the sample (19.5%) did not know that it is risky to take drugs during pregnancy without doctor's order. 2. Regarding the practices of the study subjects in relation to drug intake during pregnancy, it was observed that the majority of the sample (86%) took drugs without prescription such as vitamins and general tonics, antacids, analgesics, anti-emetics, sedatives and antibiotics to treat their minor or major complaints during pregnancy. 3. In this study, it was also found that certain factors seemed to affect women's knowledge regarding drug intake during pregnancy. It was more obvious to observe that nearly two-thirds (60.8%) of women whose age was less than 30 years were more likely to have inadequate and poor knowledge in this respect. It was observed that the majority (81.9%) of illiterate women were more likely to have inadequate and poor knowledge about drug intake during pregnancy. It was also found that nearly three-quarters (72.3%) of housewives were more likely to have poor and inadequate knowledge. It was also noticed that the majority (81.5%) of the primigravidae women were more likely to have poor and inadequate knowledge. It was also noted that the majority of women (87.1%) who had previous abortions were more likely to have poor and inadequate knowledge.

Abnormalities, Drug-Induced↗
PubMed1991

Glycocalyx of bodies versus tails of Schistosoma mansoni cercariae. Lectin-binding, size, charge, and electron microscopic characterization.

Infection with Schistosoma mansoni is initiated by penetration of the intact skin of the mammalian host with the head but not the tail of the parasite cercariae. The surface of cercariae is covered by a 1-2-micron thick carbohydrate-rich glycocalyx (gx). Furthermore, the transformation of cercariae to schistosomula (the next parasitic stage in the mammalian host) is associated with loss of gx from the bodies. To understand the role of gx in the host-parasite relationship, we have characterized the gx of both bodies and tails of S. mansoni cercariae. A fluorescent fucose-specific lectin-stained bodies and not tails of the organism. Moreover, when an enriched preparation of gx obtained by extraction with 40% aqueous phenol and exclusion from Sepharose CL-6B was subjected to affinity chromatography on insolubilized Lotus lectin, which binds fucose-containing glycans, only body gx was retained. Body gx is smaller and less negatively charged than tail gx. Electron microscopy showed that gx from bodies and tails is composed of 25-40-nm particles and fibrillar material. Carbohydrate composition of gx of bodies and tails indicate that fucose and glucose are major components, respectively. beta-Elimination experiments indicate that the linkage sugar is N-acetylgalactosamine in both cases. Upon treatment with alkaline borohydride, nearly 90% of gx of both bodies and tails was recovered as two glycan chains: I and II (Mr approximately 10,500 and 5,600, respectively). Glycan I was in both cases more negatively charged than glycan II. Fucose is the predominant sugar in glycan I of the bodies while glycan I of tails is mainly composed of glucose. The gx was resistant to several proteases. This resistance and the abundance of carbohydrate in gx may be of biological importance for survival of cercariae. The substantial differences observed between the gx of bodies and tails may provide the basis for understanding the mechanism of selective release of body gx during transformation.

Animals↗
PubMed1991

Ultrastructural localization of a protective 68,000 molecular weight antigen in Schistosoma mansoni.

Vaccination with SMW 68, an Mr 68,000 glycoprotein of Schistosoma mansoni, induces significant protection in mice against challenge schistosome infection. This resistance occurs without the use of adjuvants and without sensitizing animals to granuloma formation. Likewise, passive transfer of monoclonal antibody (MAb) 31-3B6 against SMW 68 confers partial protection against challenge infection. As a first step in understanding how the immune response to this molecule leads to resistance, SMW 68 was localized in three developmental stages of the parasite by immunoelectron microscopy using MAb 31-3B6 and polyclonal antisera raised against purified SMW 68. In cercariae and schistosomula, MAb 31-3B6 bound electron-dense granules within the head gland and similar granules in the preacetabular glands. In adult worms, SMW 68 or related antigens were found to be widely distributed in tissues. Binding of specific antisera was most pronounced in the gut and tegument of male worms, but less so in subtegumental muscles. We conclude that SMW 68 is presented to the immune system in various ways during parasite development. The protective protein or epitope is excreted, and presented on the surface and in the cytoplasm at various stages of the life cycle. The relationship of the location of this protein to its role in protective immunity is discussed.

Animals↗
PubMed1990

Direct inhibitory action of EGTA-Ca complex on reverse-mode Na/Ca exchange in Myxicola giant axons.

Giant axons from the marine annelid Myxicola infundibulum were internally dialyzed with solutions containing 22Na ions as tracers of Na efflux. In experiments performed in Li-substituted seawater, Na efflux that is dependent on external Ca ion concentration, [Ca2+]o, was measured using dialysis to maintain [Na+]i at 100 mM, which enhances the [Ca2+]o-dependent Na efflux component, (i.e., reverse-mode Na/Ca exchange). When dialysis fluid contained EGTA (1 mM) to buffer the internal Ca concentration, [Ca2+]i, to desired levels, Na efflux lost its normal sensitivity to external calcium. The inhibition was not simply due to the Ca-chelating action of EGTA to produce insufficient [Ca2+]i to activate Na/Ca exchange. The addition of EGTA inhibited Cao-dependent Na efflux even when a large enough excess of [Ca2+]i was present to saturate the EGTA and still produce elevated values of [Ca2+]i. Control experiments showed that these high values of [Ca2+]i resulted in normal Na/Ca exchange in the absence of EGTA. It is concluded that the presence of EGTA itself interferes with the manifestation of reverse-mode Na/Ca exchange in Myxicola giant axons.

Animals↗
PubMed1990

Effect of Leishmania major on human polymorphonuclear leucocyte function in vitro.

The effect of various antigens of Leishmania major promastigotes on the function of human polymorphonuclear leucocytes (PMNLs) was examined. Different concentrations of L. major antigens were incubated with isolated PMNLs for various periods and the respiratory burst was assessed by Luminol-dependent chemiluminescence. All the Leishmania antigens employed inhibited the PMNL respiratory burst by 35-64%. PMNL viability was not affected either by the concentrations or type of the parasite antigen. Oxygen free radical scavengers enhanced the action of the antigens on the PMNL respiratory burst.

Allopurinol↗
PubMed1990

Association of reduced antibody response to "SMW68" (an affinity purified schistosomal antigen) with hepatosplenomegaly in Egyptian schoolchildren infected with Schistosoma mansoni.

Studies of the pathogenesis of schistosomal infections have revealed that the occurrence of disease is so strongly related to host responses to parasite products, that schistosomiasis can be considered as an immunological disease. Further, numerous genetic and environmental factors may modify the host resistance or susceptibility to disease. To test whether hepatosplenic patients manifest different immune capabilities, and the effects of intensity of infection on immune responses; we evaluated anti-SMW68 and anti-crude antigens (SWAP & SEA) antibody levels in 100 children aged 9-15, having light and moderate S. mansoni infection (80-360 eggs/gm of stool). In this group, anti-SMW67 antibody levels (determined by ELISA) were significantly higher in those with lower levels of infection (P less than 0.001). Furthermore, the hepatosplenic patients showed a lower anti-SMW68 antibody levels than those with intestinal schistosomiasis. (P less than 0.05). We conclude that the worm burden and so the resultant morbidity may be influenced by the immune capabilities of the host. Whether enhanced antibody response to SMW68 represents acquired protective humoral immunity remains to be determined.

Adolescent↗