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Biomedical subjects

M Kamal

Publications and source records attributed to M Kamal.

At least 55 records · Page 3Linked to original sources
PubMed1994

An entomological investigation of the likely impact of cattle ownership on malaria in an Afghan refugee camp in the North West Frontier Province of Pakistan.

Field trials were undertaken to determine the effect of close proximity of humans to livestock on the human biting rates exhibited by various anophelines. The results indicate that proximity to cattle and to goats increases the subject's chances of being bitten by anophelines. Man-biting by Anopheles stephensi rose by 38% (8-68% CI) in the presence of a cow, and by 50% (16-84% CI) in the presence of two goats. Other species exhibited similar trends. These findings explain the results of an earlier trial which revealed that malaria prevalence was higher amongst families that kept cattle than those that did not. The findings are discussed in relation to existing information regarding the host preferences of local anophelines and classic theories regarding zooprophylaxis. Our findings suggest that animals are only likely to have a worthwhile prophylactic affect when the vector is zoophilic, and then only when the animals are deployed to form a barrier between that vector and man. In situations where deployment of livestock to form a zoobarrier is impractical, the livestock should be located as far from man as possible.

Afghanistan↗
PubMed1993

Stimulation of tyrosine phosphorylation without inositol lipid hydrolysis in human B lymphocytes on engaging CD72.

Occupancy of CD72 on resting tonsillar B cells by monoclonal antibodies (mAb) promotes entry into the G1 phase of the cell cycle with an accompanying increase in MHC Class II expression and provides a co-stimulus to immobilized anti-mu for driving DNA synthesis. We now report that engagement of CD72 by mAb stimulates tyrosine phosphorylation in B cells with a peak of activity seen at 5-10 min. Two major substrates of 29 and 57 kDa showed a basal level of phosphorylation which increased with time, while a 40 kDa protein and several other minor components were phosphorylated de novo on the addition of mAb to CD72. Inositol lipid hydrolysis was found to be unperturbed, although a shallow rise in the basal level of intracellular free Ca2+ was provoked on engaging CD72. Receptor cross-linking was not a requirement for signaling human B cells through CD72: simple occupancy by univalent antibody was sufficient both to trigger the rise in basal [Ca2+]i and to promote DNA synthesis.

Antigens, CD↗
PubMed1993

Prevalence of HIV infection and AIDS in Egypt over four years of surveillance (1986-1990).

Serosurveys were conducted from April 1986 to March 1990 to determine the prevalence of HIV-1 infections among Egyptians and foreigners. Sera from 29,261 high risk individuals and blood or blood product donors in Egypt, and from 10,326 foreigners were tested for HIV-1 antibodies by a recombinant HIV-1 and a recombinant combination HIV-1/HIV-2 enzyme immunoassay (EIA). Any serum found to be repeatedly reactive by EIA was tested by Western blot for confirmation of HIV-1 infection. The overall prevalence of HIV-1 infection among the Egyptians was 0.18% (54/29,261); of which 4.8% (28/582) were blood and factor VIII recipients, 0.15% (3/1961) drug addicts, 0.18% (3/1650) fever of unknown origin patients, 0.23% (6/2602) sexually transmitted disease patients, 1.9% (5/269) HIV-1 contacts, 0.07% (7/9778) international travellers, and 0.02% (2/12,070) blood/product donors. Evidence of HIV-1 infection was not demonstrated among 349 prostitutes. The prevalence of HIV-1 antibody among foreigners was 0.97% (100/10,326), who were mainly (94%) from other African countries. Among the total 54 HIV infected Egyptians, 20 developed AIDS, and at least 12 have died. Only one of the 100 infected foreigners was diagnosed with AIDS. While the number of AIDS cases has increased in Egypt over 18 months October 1988-March 1990, the overall prevalence of new HIV infections has decreased since 1988 and endemic transmission has not been documented in Egypt.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Occupancy of CD72 (the CD5 counterstructure) enhances interleukin-4-dependent CD23 expression in resting B lymphocytes.

CD72, the human homologue of murine Lyb-2, was recently identified as a counterstructure to CD5. An antibody to CD72 (BU40) has been found to mimic interleukin-4 (IL-4) both in its ability to activate resting B cells into the early G1 phase of cell cycle and to augment the expression of major histocompatibility complex (MHC) class II antigen; unlike IL-4, the CD72-clustered antibody fails to induce the expression of CD23. We now report that engagement of CD72 by the IgG monoclonal antibody BU40 potentiates the capacity of IL-4--when used at optimal concentrations--to promote CD23 production in human B cells. The degree of enhancement arising from occupancy of CD72 ranged from two- to fivefold. Importantly, antibody to CD72 was also found to diminish the concentration required for IL-4 to promote CD23 expression to a level equivalent to that maximally achieved when using IL-4 alone. Engagement of CD72 by BU40 not only increased the amount of cell-associated CD23 induced by IL-4 but also led to augmented release of soluble material into the culture medium. Monovalent Fab fragments of BU40 antibody were as efficient as intact antibodies at synergizing with IL-4 for enhanced expression and release of CD23: thus simple tethering without the need for receptor cross-linking was sufficient to invoke change through CD72. Enhancement of CD23 expression via CD72 appeared to be selective for IL-4-dependent induction: the turn on of CD23 by tumour-promoting phorbol ester was left unaltered on the addition of BU40 antibody. Engagement of CD72 had no effect on the IL-4-promoted hyperexpression of surface IgM. The findings are discussed within the context of the molecular and functional interactions occurring during T-B collaboration.

Antibodies, Monoclonal↗
PubMed1991

Caffeine-induced contractions in rabbit isolated renal artery are differentially inhibited by calcium antagonists.

Caffeine (1-60 mM) induced concentration-dependent, endothelium-independent phasic contractile responses in isolated rabbit renal artery ring preparations. For concentrations of caffeine over 2 mM, responses were mainly the result of intracellular calcium ion mobilization since they were relatively resistant to removal of calcium ions from the bathing medium. The L-type slow calcium channel blocker, nifedipine (10 microM), had no effect and high concentrations of verapamil and diltiazem (10-30 microM) only slight and inconsistent effects (not concentration-dependent) upon these caffeine responses. Likewise, the highly lipophilic calcium antagonists flunarizine and lidoflazine (3-30 microM) only slightly displaced caffeine concentration-response curves to the right and reduced the maximum response. These small inhibitory effects of flunarizine and lidoflazine were not augmented in a calcium-free medium. In contrast, the other lipophilic calcium antagonists, bepridil and fendiline (3-30 microM), produced marked, non-competitive type inhibition of caffeine responses, completely inhibiting responses to the alkaloid at the highest concentration. Furthermore, the inhibitory effects of bepridil and fendiline were markedly augmented in calcium-free medium. These results clearly differentiate bepridil and fendiline from the other calcium antagonists studied. In addition they provide further evidence for effects other than at the cell membrane which could theoretically contribute to the efficacy of bepridil and fendiline as anti-anginal agents.

Animals↗
PubMed1991

Stimulation of B lymphocytes via CD72 (human Lyb-2).

A monoclonal antibody to CD72, the 45-kDa human homolog of murine Lyb-2, was found to augment selective activation pathways in tonsillar B lymphocytes. By itself, CD72 antibody provided a weak direct stimulus to resting B cells as assessed by [3H]dThd incorporation; this was modestly enhanced on the addition of interleukin 4 (IL4) or following ligation of surface CD40. CD72-delivered signals were more evident in co-stimulation assays with phorbol ester and with a synergistic combination of IL4 and CD40 antibody, but not with calcium ionophore or a CD23 antibody; rapidly cycling B cells were refractory to signaling via CD72 whether or not other co-stimuli were present. A unique feature of the CD72-delivered signal was its ability to enhance synergistically stimulations triggered with immobilized antibody to IgM, while failing to augment responses initiated by soluble anti-mu. On direct culture of resting B lymphocytes with CD72 antibody, an approximately twofold increase in the expression of major histocompatibility complex class II DQ antigen was observed, an augmentation similar to that achieved with IL 4; CD72 antibody also mimicked IL 4 in its ability to drive G0 cells into the early G1 phase of cell cycle. In contrast to IL 4-promoted stimulation, CD72 antibody failed to up-regulate the surface expression of either IgM or the CD23 antigen. CD72 expression itself was found to be weak on resting B lymphocytes and was modestly enhanced following culture with IL 4. The findings are discussed with reference to observations made on the triggering of murine B lymphocytes through Lyb-2 and within the context of previously defined human B cell activation pathways.

Antigens, CD↗
PubMed1990

HIV infection in Egypt: a two and a half year surveillance.

From April 1986 to mid-October 1988, 19,767 blood samples from individuals of 27 Governorates in Egypt were screened for antibodies to HIV-1. Risk groups included: drug addicts, prostitutes, patients with sexually transmitted diseases or fever of unknown origin, blood or blood product recipients, patients with mental disorders, and contacts of HIV-infected persons. Sera from routine blood donors and foreigners were also tested. All samples which reacted repeatedly by commercial ELISAs were assessed by Western blot (DuPont) for confirmation. Results indicated that 139 (0.70%) of the sera produced repeatedly reactive results by ELISA. Sixty-nine of these were confirmed by Western blot as HIV seropositive. This constituted 0.35% of the total population tested. Only 26 (0.15%) of the Egyptians tested were positive and a total of seven sero-positive individuals were classified as having clinical AIDS. All Egyptian blood donors were negative. Data generated during this 2.5-year HIV serosurvey indicate that the prevalence of confirmed HIV infection in Egypt was exceptionally low, and suggest that HIV is not endemic in Egypt, since all 26 sero-positive Egyptians were linked to HIV exposure abroad.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Immune dysfunctions in psychiatric patients.

Alterations in the serum proteins and immunoglobulins have been investigated in the search for the possible etiological causes of schizophrenic patients. The results, so far, have been varied and inconclusive. We assayed serum immunoglobulins, and antinuclear antibody (ANA) titres in 94 randomly selected, recently hospitalized, psychotic patients. A complete physical, neurological, laboratory and electrophysiological examination was conducted on each patient. Systems survey and family, as well as past histories were obtained. Our results indicated that 12 patients had high titres of ANA and none of them had any other clinical evidence of autoimmune disease. This finding did not correlated with age, sex, diagnosis, or duration if illness, but an association with the medications that the patients were receiving, was noted. The elevation in ANA titres seems to be related to use of lithium as well as neuroleptics. Our data suggests that all neuroleptics can produce high ANA titres. Systematic study of this phenomenon and their long-term consequences warrant further exploration.

Adolescent↗