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A A Mahmoud

Publications and source records attributed to A A Mahmoud.

At least 73 records · Page 4Linked to original sources
PubMed1986

Discrepancies in outcome of a control program for schistosomiasis haematobia in Fayoum governorate, Egypt.

A large scale mollusciciding and chemotherapy program in the Fayoum area of Egypt was reported to have decreased prevalence of schistosomiasis haematobia from 46% to 7% in approximately 12 years. In order to assess the uniformity of results reported, we have studied the prevalence and intensity of urinary tract disease in a random sample of children aged 6 months-12 years in 3 areas selected on the basis of distance from the main canal supplying Fayoum and where mollusciciding was applied. Only 1 location near the main canal showed low prevalence (2.2%), while in the other 2 areas prevalence was 75.3% and 61.3%. Intensity of infection and disease were significantly more in the latter 2 locations. Following chemotherapy, a marked reduction in prevalence and intensity of infection and reversal of pathology was seen. Since the reported favorable results of the Fayoum project were used to implement a wider control program in southern Egypt, an independent assessment must be included in future plans.

Child↗
PubMed1986

Modulation of human neutrophil effector functions by monoclonal antibodies against surface membrane molecules of 94,000 and 180,000 molecular weight.

Function-related antigens on the neutrophil (PMN) surface were identified using two newly developed PMN-specific mouse monoclonal antibodies. These IgG antibodies, designated Ab 1-14 and Ab 1-15, were selected for detailed study after initial testing revealed their significant inhibition of PMN superoxide generation in response to N-formyl-Met-Leu-Phe (FMLP) (64% for 1-14 and 64% for 1-15; P less than .05). In further experiments, Ab 1-14 augmented PMN adhesion (by 111%; P less than .01) and degranulation (by 52%; P less than .05) in response to FMLP, while Ab 1-15 inhibited these responses by 42% and 29%, respectively (P less than .05). Ab 1-14 reduced PMN chemotaxis in response to FMLP by 37% (P less than .02), and unlike Ab 1-15, Ab 1-14 significantly reduced unstimulated PMN binding of complement-coated sheep red blood cells. Ab 1-14 and Ab 1-15 significantly reduced PMN superoxide production in response to phorbol myristate acetate (PMA) (14% and 23%, respectively; P less than .05). Whereas 1-14 was found to increase PMA-induced cell degranulation significantly (175%), Ab 1-15 did not alter degranulation response to PMA. Immunoprecipitation showed that Ab 1-14 and Ab 1-15 recognized respective surface antigens of 94,000 mol wt and 130,000 to 180,000 mol wt. Our findings suggest that the surface molecules identified by these two monoclonal antibodies play a significant role in neutrophil activation by both FMLP and PMA.

Animals↗
PubMed1986

Stage and species specificity of antigens encoded by two geographic strains of Schistosoma mansoni mRNA.

Proteins translated in vitro from Schistosoma mansoni adult worm mRNA were assessed for their antigenic specificities compared to different stages, strains and species of the parasite. RNA was extracted from both Puerto Rican and Brazilian parasites and directed the synthesis of high molecular weight proteins. Preabsorption of immune human serum with schistosomula was used to determine whether the in vitro translated proteins contained antigens shared between the adult and this immature stage. Three antigens (Mr 36,000, 29,000, 18,000) were observed to be present in both stages. When adult worm mRNA from 2 different geographic strains of S. mansoni (Puerto Rican and Brazilian) were compared, certain antigenic differences were found in their in vitro translation products (proteins at Mr 78,000, 26,000, 24,000, 22,000, 15,500), suggesting that different antigenic pools may exist in nature. The species specificity of the in vitro proteins was assessed using individual sera from humans whose species of schistosome infection and egg counts were known. Immunoprecipitation with these sera demonstrated that a large number of immunologically cross-reactive proteins were shared between S. mansoni and Schistosoma haematobium but not Schistosoma japonicum. Antigens or antigen complexes at Mr 47,000 and 37,000 were detected only in the immunoprecipitations using anti-S. mansoni sera, whereas an antigen of Mr 39,000 was precipitated only by anti-S. haematobium sera. The recognition of any 1 antigen or group of antigens, however, did not distinguish between intensities of infection.

Animals↗
PubMed1985

Attempts to induce resistance to Schistosoma mansoni and S. haematobium in Kenyan baboons (Papio anubis) using non-specific immunostimulants.

Non-specific immunostimulants were used in an attempt to protect baboons from infection by schistosomes. Subcutaneous vaccination with cord factor (4.50 mg) and muramyl dipeptide (4.56 mg) 6 days before percutaneous exposure to 3000 Schistosoma haematobium cercariae/baboon (c.p.b.) failed to protect naive baboons: baboons with a 7-month-old, 5000 c.p.b. S. haematobium primary infection had developed too strong a natural immunity to detect any protection attributable to vaccination. Subcutaneous vaccination with 0.4 ml of Bacillus Calmette-Guerin (BCG, 1-8 X 10(8) colony forming units/ml) 4 days before exposure to 1000 c.p.b. S. mansoni gave a significant (38%) reduction in worm load compared with controls. However, vaccination with 0.8 (intramuscular) and 0.2 (intradermal) ml of BCG 11 days before exposure to S. mansoni 800 c.p.b. did not protect naive baboons, nor did it significantly reduce challenge worm recovery from baboons with a 13-week-old, 500 c.p.b. S. mansoni primary infection. Obvious pathology was seen at the site of vaccination in the first but not the second BCG experiment. These results partly support the findings in mice that non-specific macrophage and monocyte activators give partial protection against schistosome infections but they also illustrate that rodents and primates do not necessarily react identically. Hence, findings from rodent models should be extrapolated to man with some caution.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1985

Evaluation of a purified Schistosoma japonicum glycoprotein egg antigen for the immunodiagnosis of infection in man.

A purified glycoprotein, glycoprotein-2, which was isolated from Schistosoma japonicum soluble egg antigen, was tested in an enzyme-linked immunoadsorbent assay for its potential as an immunodiagnostic reagent. Using empirically-derived criteria of endpoint titer, 39/40 sera from S. japonicum-infected individuals were scored correctly as positive in a blind test. Of these, 26/40 were from individuals who excreted fewer than 100 eggs per gram of stool. No cross reactions were observed with sera from uninfected individuals (0/20) or from individuals infected with S. mansoni (0/22), Trichinella spiralis (0/6) or Brugia malayi (0/4). Cross reactions were observed with 3/24 individuals infected with S. haematobium who excreted greater than 2,000 eggs per 10 ml urine. Glycoprotein-2 appears to satisfy the requisite criteria of specificity and sensitivity to warrant further evaluation.

Animals↗
PubMed1985

Glycopeptides in soluble egg antigen of Schistosoma mansoni: isolation, characterization, and elucidation of their immunochemical and immunopathological relation to the major egg glycoprotein (MEG).

The major egg glycoprotein (MEG) of Schistosoma mansoni was purified by ion-exchange chromatography of glycoprotein fraction obtained from soluble egg antigen (SEA) by lectin affinity chromatography. Small carbohydrate-rich fragments (CRF) contained in the glycoprotein fraction of SEA were isolated by ultrafiltration followed by dialysis (10 to 13 kd). Comparison of MEG and CRF yielded the following results: purified MEG (70 kd) contains about 77% carbohydrate, and CRF contains 92.5% carbohydrate. When radioiodinated and run by SDS-PAGE, each yielded a single band with respective Rf values of around 0.33 and 1.0 CRF is capable of inhibiting, in a Farr-type RIA, the binding of 125I-MEG to serum from chronically infected mice. Furthermore, CRF and MEG exhibit a single and continuous line of radioimmunodiffusion. CRF, unlike SEA, SEA glycoproteins, or purified MEG, is incapable of eliciting delayed footpad swelling in egg-sensitized mice or of inducing granulomatous hypersensitivity, when given at amounts equivalent to or higher than MEG by protein or carbohydrate content. Thus, whereas SEA, SEA glycoproteins, or MEG elicited in a representative test net swelling of 0.28 mm, 0.34 mm, and 0.29 mm, respectively, CRF gave net swellings of 0.06 mm, similar to the control value (0.07 mm) in unsensitized mice. Also, mice sensitized to viable eggs, SEA, or purified MEG exhibited, after i.v. challenge with viable eggs, a mean area of granulomas in the lungs of 12,389 micron2, 16,412 micron2, and 12,354 micron2, respectively, as compared with 7940 micron2 in CRF-sensitized mice and 8428 micron2 in unsensitized control mice. Thus, CRF appears to contain fragments of MEG that are serologically active but immunopathologically inactive at the concentrations used.

Animals↗
PubMed1985

Effector mechanism of host resistance in murine giardiasis: specific IgG and IgA cell-mediated toxicity.

The role of specific serum and milk anti-Giardia muris antibodies in mediation of host-effector responses to this enteric pathogen is unknown. We have investigated antibody-dependent cell-parasite interactions, potentially important as mediators of protection against infection at the mucosal surface. Elicited mouse peritoneal neutrophils and macrophages were incubated with G. muris trophozoites in the presence of either serum or milk antibodies, and their adherence and phagocytosis of the parasites were assessed. The percentage of trophozoites with adherent neutrophils increased significantly in the presence of heat-inactivated immune rabbit serum (93.5% +/- 6.5) and immune mouse milk (54.4% +/- 11.3) and their purified IgG (35.2% +/- 9.7) and secretory IgA fractions (48.0% +/- 12.3) when compared with incubation in RPMI-10% FCS (21.7% +/- 13.9). Similarly, macrophage adherence to trophozoites increased from 49.7% +/- 14.3 in medium alone to respective values of 92.8% +/- 7.1 in immune rabbit serum and 77.3% +/- 11.0 in immune milk. Phagocytosis of parasites by macrophages also was enhanced after incubation in immune rabbit serum (48.0% +/- 4.0) and immune mouse milk (35.0% +/- 5.0) when compared with the percentage of trophozoites ingested when cells and parasites were incubated in RPMI-10% FCS (3.3% +/- 3.0). Transmission electron microscopy showed ingestion of parasites by neutrophils or macrophages after 15 min of incubation. Morphologic evidence of intracellular parasite injury was observed at 6 hr. A decrease in parasite infectivity also resulted when trophozoites were incubated with neutrophils or macrophages and a source of antibodies, and intragastrically fed to weanling mice. These observations show that both antitrophozoite IgG, secretory IgA, and mouse phagocytic cells interact in vitro to promote parasite clearance. Because both the humoral and cellular components of this system are found intraluminally in the small intestine and in milk, they may represent a biologically relevant protective response against giardiasis.

Animals↗
PubMed1984

Some aspects of the epidemiology of cutaneous leishmaniasis in the Al-Kharaj area of Saudi Arabia.

Four hundred and thirteen patients with skin ulcers were clinically diagnosed as suffering from cutaneous leishmaniasis; 82 (approximately 20%) of these cases were confirmed microscopically. Ulceration occurred mainly on the exposed parts of the body. Of the total cases 69% were Egyptian labourers, 14% Saudis and the remaining 17% Syrian, Pakistani, Yemeni or Filippino. Most of the Saudi patients were children aged up to ten years. Two Rattus rattus collected during the study had skin ulcerations on the face, indicating possible infection with leishmaniasis. Poor living conditions on the farms seem partly responsible for the high rate of incidence of cutaneous leishmaniasis among the labourers.

Adolescent↗
PubMed1984

Host granulomatous response in schistosomiasis mansoni. Antibody and cell-mediated damage of parasite eggs in vitro.

In chronic schistosomiasis mansoni the major pathologic lesions are granulomas surrounding eggs deposited in host tissues. Parasite ova release antigenic material that sensitize the host, resulting in the development of delayed-type hypersensitivity granulomas. The objectives of the present study were to assess the ability of components of the host granulomatous response to induce biochemical and biologic alterations in eggs in vitro, and to correlate these with the capacity of ova to induce granulomas in vivo. An assay of egg tricarboxylic acid cycle activity was developed by use of 2-[14C]acetate as substrate and measurement of accumulation of released 14CO2. Addition of human granulocytes (96% neutrophils, 4% eosinophils) to eggs (cell/egg ratio 1,000:1) and heat-inactivated normal human serum reduced predicted egg 14CO2 generation by 15.6 +/- 3.0%. This effect was greater in the presence of sera of subjects with schistosomiasis (25.6 +/- 2.8% reduction) or when complement was present (24.4 +/- 4.0%). Autologous eosinophils and neutrophils were equally effective in decreasing egg 2-[14C]acetate metabolism (25.6 and 21.4% reductions, respectively). Since the biological role of schistosome eggs relates to their ability to hatch and produce miracidia, we evaluated the effect of granulocytes and sera on this function. The hatching rate of eggs incubated with normal serum was 52.8 +/- 3.3 miracidia/100 eggs; this value decreased to 37.0 +/- 2.6 when granulocytes were added (P less than 0.01). Granulocytes plus antibody- or complement-containing sera led to hatching rates of 23 and 20 miracidia/100 eggs. When ova were pre-incubated with granulocytes and various sera and injected into mice, the areas of egg-induced pulmonary granulomas measured 8 d later were reduced 32 to 45% as compared with lesions elicited by parasite eggs not exposed to granulocytes. Exposure of antigen-coated Sepharose beads to granulocytes and immune serum before injection into mice also led to a reduction in granuloma formation as compared with beads pre-incubated with serum alone. These data indicate that granulocytes in conjunction with antibodies and complement inflict biologically relevant toxic effects on eggs that are manifest in vivo by a decreased ability to elicit granulomas.

Acetyl Coenzyme A↗
PubMed1984

The effect of a single dose of metrifonate on Schistosoma haematobium infection in Egyptian school children.

Egyptian school children infected with Schistosoma haematobium and treated with a single dose of metrifonate, 10 mg/kg body weight, had a marked reduction in urine egg counts reaching 90% during a 30-week follow-up. While cure rate was higher among lightly infected persons, percentage reduction in egg counts was greater among the heavily infected. After a summer period of probable high risk exposure reinfection rate in those children who were treated and cured was 4.7% as compared to 6% in previously uninfected children.

Child↗
PubMed1983

Effect of targeted mass treatment on intensity of infection and morbidity in schistosomiasis mansoni. 3-year follow-up of a community in Machakos, Kenya.

The effect of targeted mass treatment, a new strategy for cost-effective control of schistosomiasis mansoni based on administering single-dose chemotherapeutic agents to individuals with disease manifestations (hepatosplenomegaly) or heavy infections, was evaluated in an endemic area in Kenya. Two years after treatment of subjects with hepatosplenomegaly, the mean liver midsternal-line measurement decreased from 6 x 5 +/- 0 x 6 to 2 x 9 +/- 0 x 5 cm and the mean faecal egg count dropped significantly from its pretreatment level of 1090 +/- 290/g to 88 +/- 31/g. Targeted chemotherapy was then administered to a group of 122 subjects with faecal egg counts greater than or equal to 400/g. A similar maintained decrease in egg counts after chemotherapy was demonstrated in this group; mean egg count after one year was 115 +/- 17/g compared with 1250 +/- 232/g before treatment. The yearly rate of acquisition of heavy infection in this community was low (7%) and did not differ significantly in the uninfected, lightly infected, or heavily infected (and treated) groups.

Adolescent↗
PubMed1983

Species-related innate resistance to Schistosoma mansoni. Role of mononuclear phagocytes in schistosomula killing in vitro.

Resistance to infection with the multicellular parasite Schistosoma mansoni has been previously demonstrated to vary among several host species. The current investigation was designed to examine the basis for this species-related resistance in vitro. Adherent peritoneal macrophages or peripheral blood mononuclear cells from several species of host animals were incubated with S. mansoni schistosomula for 18-24 h; parasite viability was then assayed by methylene blue exclusion. Peritoneal exudate macrophages from susceptible species, such as mice (C57Bl/6) and hamsters killed, respectively, 6.6 +/- 2 and 8.0 +/- 2% of incubated schistosomula. In contrast, cells from resistant species: rats, guinea pigs, and rabbits, killed 21 +/- 2.3, 15 +/- 4.6, and 17 +/- 5.5%, respectively. Furthermore, blood monocytes from rabbits resulted in a mean of 25.9 +/- 2.8% dead organisms. Schistosomula killing by mononuclear phagocytes obtained from resistant species (rats or rabbits) was dependent on the cell/parasite ratio. Significant schistosomula mortality resulted from culture supernatants of rat macrophages or rabbit monocytes. Killing by cells from both species was significantly reduced upon addition of L-arginine, while catalase reduced killing only by rat macrophages. We conclude that mononuclear phagocytes may play a key role in species-related innate resistance to schistosomiasis; their in vitro schistosomulicidal activity parallels the known in vivo susceptibility of the donor species. Killing is mediated by lysosomal enzymes (arginase) and by products of oxidative metabolism, the predominant mechanism depends on the specific animal species.

Animals↗
PubMed1982

The ecology of eosinophils in schistosomiasis.

Schistosomiasis is characterized clinically by an increase in eosinophil counts in bone marrow and peripheral blood. This eosinophil response is also manifest pathologically by cell accumulation around the invading schistosomula and the parasite ova retained in host tissues. The parasites undergo a series of antigenic and maturational changes within the host that result in two distinct peaks of eosinophilia. Furthermore, products of parasite interaction with complement, antibodies, and sensitized T lymphocytes have been shown to enhance eosinophil migration and chemotaxis. Eosinophils, which constitute a prominent cellular component in the host response to the schistosomes, may be activated biochemically. Both in vivo and in vitro studies have delineated a protective role for the eosinophils against schistosomula and eggs. The ability of these cells to destroy multicellular parasites has been shown to be due to highly reactive oxygen reduction products or to release of cationic or major basic proteins from the granules.

Animals↗