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Biomedical subjects

I Melamed

Publications and source records attributed to I Melamed.

At least 37 records · Page 2Linked to original sources
PubMed1991

Tyrosine phosphorylation is essential for microfilament assembly in B lymphocytes.

The B cell antigen receptor regulates the tyrosine kinase signal transduction pathway and it mediates a variety of morphological changes such as capping and membrane ruffling. The relationship between these two events is unclear. We show here that cross-linking the antigen receptor on human B lymphocytes, in addition to increasing tyrosine phosphorylation of specific substrates, induces the conversion of G-actin to F-actin. Preincubation of B lymphocytes with two different tyrphostins blocked anti-IgM-induced tyrosine phosphorylation and actin polymerization. The ability of the tyrphostins to block anti-IgM induced conversion of G-actin to F-actin indicates that a tyrosine kinase acts as an essential link between the B cell antigen receptor the early changes in cytoskeletal reorganization.

Actin Cytoskeleton↗
PubMed1991

Benefit of ketotifen in patients with eosinophilic gastroenteritis.

PURPOSE: Eosinophilic gastroenteritis (EG) is a rare condition of unknown etiology characterized by vomiting, diarrhea, protein-losing enteropathy, and eosinophilic infiltration of the gastrointestinal mucosa. The potential association of EG with allergy and related mast-cell release of mediators led us to evaluate the ability of an antihistamine drug to modify the course of the disease. PATIENTS AND METHODS: Six patients with protracted gastrointestinal symptoms were diagnosed with EG because of histologic evidence of predominantly eosinophilic infiltrates in the gastrointestinal mucosa. Each patient was treated in an open trial for 12 months with ketotifen (Zaditen), an antihistamine of the H1 class that is known to stabilize mast cells. RESULTS: All six patients improved clinically; four also gained weight. Total serum IgE levels decreased after 4 to 6 months of therapy. Clearing of eosinophilic infiltrates was documented in the four patients who underwent follow-up mucosal biopsies. CONCLUSION: We conclude that ketotifen treatment represents a safe and effective alternative to traditional systemic corticosteroid therapy for treatment of EG.

Adolescent↗
PubMed1990

Coffee and the immune system.

The effect of coffee consumption on the immune system, studied in 15 men and women, showed that the responses to PHA and Con A were about one-third lower during coffee drinking compared to a period of abstinence from coffee (117335, 99856 and 181236, 153315, P less than 0.004, 0.009 respectively). There was no effect on total T- or B-cells. There was no statistically significant change in the number of suppressor T-cells (20, 26; P = 0.1) or NK cells (20, 26; P = 0.014). Chemotaxis was higher in the coffee period at all concentrations. This exploratory study suggests that coffee intake modifies various measures of the immune function. The clinical relevance of the findings is not clear, and further studies aimed at delineating the constituents responsible for the effects observed are recommended.

Adult↗
PubMed1990

ELISA for Campylobacter jejuni antibodies in Israeli children with diarrhea and in healthy soldiers.

An ELISA test was employed to detect Campylobacter jejuni antibodies, using as antigen the glycine-HCl buffer extract of a local isolate. The antibody response (IgG, IgA and IgM) was examined in a group of 32 children (age 0-12 years) with C. jejuni enteritis diagnosed by the isolation of the agent. Controls were represented by two groups of children matched according to their age and sex: a) children with enteritis of unknown etiology, and b) healthy children. In addition, 66 healthy soldiers (aged 18-19), from whom serum specimens were collected during the first year of military service, were tested. The results indicated that the serodiagnosis of C. jejuni infection by ELISA is specific and sensitive regarding each Ig tested. The test for IgG was the most sensitive (72%) and that for IgM the most specific (100%). The healthy young adult soldiers showed significantly higher mean levels of IgG and IgA antibodies than the healthy children, suggesting that in Israel exposure to C. jejuni commonly occurs during early childhood. The ELISA for C. jejuni can improve the diagnosis of campylobacteriosis for clinical and epidemiological purposes.

Adult↗
PubMed1989

Tuftsin stimulates IL-1 production by human mononuclear cells, human spleen cells and mouse spleen cells in vitro.

Human peripheral adherent cells from splenectomized subjects, human spleen cells and mouse spleen cells were tested for IL-1 production in vitro in presence or absence of synthetic tuftsin (Thr-Lys-Pro-Arg). Application of synthetic tuftsin to peripheral blood adherent cells from normal donors as well as from splenectomized subjects induces IL-1 production. In splenectomized subjects the extent of induction was more evident than in controls. In human splenic cells tuftsin stimulates IL-1 production without KLH or LPS. In mouse spleen cells tuftsin alone did not stimulate the IL-1 secretion. However, addition of tuftsin to mouse spleen cells incubated with KLH augmented significantly the IL-1 secretion. As removal of the spleen leads to tuftsin deficiency, our present findings may perhaps explain the fulminant nature of the postplenectomy sepsis and some immune disturbances described in the postplenectomy state.

Animals↗
PubMed1987

Serum immunoglobulin A levels and ethnicity in an Israeli population sample.

Serum IgA concentrations were measured in 1799 healthy Israeli military recruits (698 women and 1101 men) using an automated nephelometric system. The overall prevalence of IgA deficiency defined at a level of less than 50 mg/liter was 1.0 +/- 0.46% (95% confidence limits). No significant difference was found between the sexes in the mean values of serum IgA. Statistically significant ethnic differences were evident. Recruits of European origin had lower serum IgA concentrations than the North African, Israeli, or Asian origin groups. Whether the apparently high prevalence of IgA deficiency in this young population in Israel has clinical significance is at present unknown.

Africa, Northern↗
PubMed1987

Age distribution of anginose mononucleosis.

The age distribution of anginose infectious mononucleosis in children was analysed retrospectively for the years 1966-85. During that period the disease became significantly more common in children of a young age and less common in older children. This shift could not be attributed either to socioeconomic conditions or to the diagnostic methods used.

Adolescent↗
PubMed1985

Inhibition of lymphocyte response to mitogens by dipyridamole: preliminary findings.

It has been recently noted that dipyridamole (DP) may be involved in certain immunological reactions, in addition to its antiplatelet action. In the present investigation the mitogenic response of human lymphocytes from three groups of subjects to 3 different lectins was examined. In both the experimental group treated over a short period and in the controls a highly significant decrease in the mean lymphocyte response to all 3 mitogens was noted following 3 days of DP administration. The response remained low after an additional 3 days of treatment. Discontinuation of drug administration was followed by a significant increase in response to two mitogens, concanavalin A (Con A) and pokeweed mitogen (PWM). The response to phytohaemagglutinin (PHA) extent only increased to a small, non-significant. No change in the mean mitogenic response was detected in the group undergoing long-term treatment. The mechanism by which DP alters lymphocyte activity is as yet unknown.

Adult↗
PubMed1985

The immune system in isolated IgA deficiency.

The immune systems were compared in 23 subjects with isolated IgA deficiency and 15 controls with normal levels of IgA. The IgA deficient group had higher levels of serum IgM, and lower stimulation indices for the mitogens Con A, PWM and PHA; only the index for PHA was statistically significant. Their suppressor T-cell activity was decreased and chemotactic activity significantly decreased. They also exhibited a decrease in Leu 3, and a significantly lower ratio of Leu 3 to Leu 2. The mean percent of positive NBT neutrophils was decreased. An imbalance in the immunoregulatory mechanism is suggested as a possible explanation for IgA deficiency.

Adult↗
PubMed1984

Association of the hemophilia A carrier state and hemorrhagic thrombocytopathy with dilatation of the platelet membrane complex.

Associations of hereditary abnormalities of the factor VIII complex and hereditary platelet disorders have previously been reported in 12 families. Another family is reported in which 6 members had a bleeding tendency and thrombocytopathy characterized by impaired platelet aggregation and dilatation of the platelet membrane complex. Apart from the platelet function abnormalities the proband had diminished levels of factor VIII clotting activity (36 U/dl) and factor VIII clotting antigen (31%) while factor VIII-related antigen and ristocetin cofactor were normal. The other affected family members had normal levels of factor VIII:C. Consequently, the proband was defined as a hemophilia A carrier manifesting also hereditary thrombocytopathy.

Adult↗
PubMed1983

Campylobacter enteritis in normal and immunodeficient children.

Campylobacter fetus subspecies jejuni (CBJ) has been recently recognized as a common pathogen in bacterial gastroenteritis in children. During a period of 16 months, 51 cases of C fetus subspecies jejuni gastroenteritis were diagnosed. Five of the children in whom the cases were diagnosed were previously known to be immunodeficient: two had X-linked agammaglobulinemia, one had agammaglobulinemia, one had combined immunodeficiency, and one had transient hypogammaglobulinemia. Average duration of fever and diarrhea was longer in the five immunodeficient children (15 and 23 days, respectively) compared with the normal children (four and five days, respectively). Excretion of C fetus subspecies jejuni in stool persisted for 20 to 27 days in four of the immunodeficient children and for one year in the fifth, whereas normal children excreted C fetus subspecies jejuni for only four to 16 days. Campylobacter fetus subspecies jejuni may be added to the list of bacterial pathogens most likely to infect immunodeficient children, especially those with a defect of the humoral system.

Campylobacter Infections↗
PubMed1983

Overdose of booster tetanus toxoid given in error: a clinical study.

16 reserve soldiers received an overdose of tetanus toxoid vaccine (5 ml instead of 0.5 ml) in error. We assessed the incidence and severity of adverse reactions and determined tetanus antibody titer immediately and after 5 days, 1 month and 1 year, and compared it with the titers in a control group of 20 soldiers. The incidence and severity of reactions was significantly higher in the overdose group. The mean tetanus antibody titer rose to similar levels in both groups after 1 month (153.75 +/- 82.5 IU/ml and 62.02 +/- 42.15 IU/ml respectively) but decreased sharply after 1 year in the overdose group.

Adult↗
PubMed1983

The immune system in familial Mediterranean fever.

Familial Mediterranean fever (FMF) is a genetic disorder with an obscure aetiology. In attempts to investigate a possible immunoregulatory imbalance involved in this disease we tested 24 FMF patients for suppressor T cell activity and for chemotaxis of mononuclear cells. The suppressor T cell activity and chemotaxis were decreased in untreated FMF patients as compared to colchicine treated patients or normal controls. Amyloid FMF patients manifested significantly increased chemotactic activity, while the suppressor T cell activity was normal. This finding may extend our knowledge concerning the immune mechanism involved in FMF.

Adolescent↗