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Biomedical subjects

A Theron

Publications and source records attributed to A Theron.

At least 19 recordsLinked to original sources
PubMed1989

Investigation of the relationships between plasma levels of ascorbate, vitamin E and beta-carotene and the frequency of sister-chromatid exchanges and release of reactive oxidants by blood leucocytes from cigarette smokers.

In this study the frequencies of sister-chromatid exchanges (SCEs) were correlated with measurements of the release of reactive oxidants by phagocytes, as determined by luminol-enhanced chemiluminescence (LECL), and levels of the anti-oxidants ascorbate, beta-carotene and vitamin E in blood specimens taken from 65 young asymptomatic cigarette smokers. Increased SCE frequencies correlated with LECL responses (p less than 0.0075) of activated blood phagocytes. Anti-oxidant levels did not correlate with either LECL or SCEs. These findings indicate that increased generation of reactive oxidants by circulating phagocytes from cigarette smokers are associated with cytogenetic changes.

Adult↗
PubMed1985

[Factors responsible for preventing the carrying out of the Schistosoma mansoni cycle in the waters of Grande Terre of Guadeloupe (French Antilles)].

Different surveys which have been conducted in ponds and pools in the Grande Terre of Guadalupe, have demonstrated the absence of Schistosoma mansoni transmission in spite of apparent favourable ecological conditions. Four hypothesises can explain this absence of transmission: 1 - the presence of Biomphalaria glabrata populations non-susceptible to the infestation by S. mansoni. 2 - Ecological conditions unfavourable to the survival of parasitized snails. 3 - Ecological conditions unfavourable to the production, survival and infectivity of the S. mansoni cercariae. 4 - Factors causing the non-contamination of the snails. The results show that the transmission of schistosomiasis mansoni is possible in the ponds and pools of Grande Terre. Only human behaviour is responsible for the absence of actual transmission in the waterbodies of this area. Man breaks the life-cycle of the parasite by avoiding all fecal pollution and therefore all snail contamination.

Animals↗
PubMed1985

Investigation of the protective effects of the antioxidants ascorbate, cysteine, and dapsone on the phagocyte-mediated oxidative inactivation of human alpha-1-protease inhibitor in vitro.

Oxidants derived from the atmosphere or from activated pulmonary phagocytes mediate functional inactivation of alpha-1-protease inhibitor (alpha-1-PI). Chronic exposure to these oxidants may cause emphysema. In this study we have investigated the effects of the antioxidants ascorbate, cysteine (10(-4) M to 10(-1) M), and dapsone (10(-6) M to 10(-3) M) on the oxidative inactivation of human alpha-1-PI by leukoattractant-activated polymorphonuclear leukocytes (PMNL) in vitro. During exposure of alpha-1-PI to stimulated PMNL in the presence of ascorbate and cysteine at concentrations of greater than 10(-4) M and dapsone at greater than 10(-6) M, the elastase inhibitory activity of alpha-1-PI was preserved. However, exposure of the alpha-1-PI to the antioxidants subsequent to PMNL-mediated oxidative inactivation was not associated with reactivation of elastase inhibitory capacity. Ascorbate, cysteine, and dapsone at concentrations that caused 50% protection of alpha-1-PI did not affect degranulation or the binding of radiolabeled leukoattractant to PMNL. It is suggested that the protective effects of the antioxidants are related to their ability to scavenge superoxide and oxidants generated by the PMNL-myeloperoxidase/H2O2/halide system. Because the effects of ascorbate and especially those of dapsone were observed at concentrations of these agents that are attainable in vivo, our results may have clinical significance.

Antioxidants↗
PubMed1984

[Physiological dangers of the use of Cannabis sativa].

The increasing use of Cannabis sativa (dagga) raises the question whether it could cause physical harm to the user. The earlier belief that cannabis could be used effectively in the treatment of various illnesses contributes to the tendency of cannabis users to reject the possibility that it may be harmful to their health. Scientific research, however, indicates that cannabis has no medicinal value. On the contrary, it may cause serious physical damage.

Animals↗
PubMed1984

[Activities of a Schistosoma mansoni focus of transmission in Martinique (French Antilles)].

A focus of intestinal schistosomiasis was discovered in november 1981 in Martinique in the Saint-Pierre area. An analysis of its structure and of the mecanisms of the transmission of the parasite was carried out between 1981 and 1983. This focus presents the following particularities: a transmission site very small constituted by water cress beds; a small human population infected with a prevalence of 13% (positive stools) to 41,3% (positive serologies); a weak fecal contamination of the water; a non functioning sewage stabilization tank is responsible for this contamination; a rich population of the snail host Biomphalaria glabrata (40,5 to 256,3 Bg/m2) with a low prevalence of infestation (0,13 to 0,59%); low cercarial densities in the water cress bed waters; a very low contamination of the Roxelane river water in to which the water from the water cress beds flows. The epidemiological importance of this contamination has proved very low but not altogether absent. This focus appears as a particular case in Martinique because all the surveys which have been conducted in the island to date has not uncovered a similar example.

Animals↗
PubMed1983

The effects of benoxaprofen on mononuclear and polymorphonuclear leucocyte motility. An in vitro and in vivo study.

Benoxaprofen at concentrations well within the normal therapeutic range was found to cause significant inhibition of both mononuclear leucocyte (MNL) and polymorphonuclear leucocyte (PMNL) motility in vitro. The ingestion of benoxaprofen 600 mg also resulted in a significant reduction of MNL migration, while co-incubation of control PMNLs with 25% heat-inactivated serum from healthy subjects resulted in a very significant inhibition of PMNL motility. Serum IgG levels also dropped significantly after benoxaprofen ingestion. These results show that human PMNL and MNL migration is significantly suppressed by benoxaprofen both in vitro and in vivo and that the anti-inflammatory activity of the drug is mediated at least partly by inhibition of the migration of both the cell types and suppression of immunoglobulin production, possibly by induction of suppressor MNL activity.

Adult↗
PubMed1983

Ascorbic acid in bronchial asthma.

Sixteen White children with bronchial asthma were divided into two groups; one received standard anti-asthma chemoprophylaxis (SAC) and the other SAC supplemented with 1 g ascorbic acid (Redoxon) given as a single daily dose for a 6-month period. In 10 patients the effects of ascorbic acid on exercise-induced bronchoconstriction (EIB) were assessed by comparing the pre-ascorbic acid results with those obtained 2 1/2 hours after the intravenous injection of 1 g ascorbic acid. Immunological investigations performed on the two groups were assessment of polymorphonuclear leucocyte (PMNL) motility, phagocytosis and nitroblue tetrazolium reduction and measurement of secretory IgA, serum immunoglobulin and total haemolytic complement levels and levels of the components C3 and C4, alpha 1-antitrypsin, antistreptolysin O (ASO), C-reactive protein and antibodies to certain respiratory viruses. These investigations were performed before and 1, 3 and 6 months after the commencement of therapy. Radio-allergosorbent testing for sensitivity to four common allergens was carried out at the outset and after 6 months of therapy. Injection of ascorbic acid had no detectable effects on the degree of EIB. Slight but not significant immunological changes were observed in the SAC group over the 6-month study period. However, in the SAC plus ascorbic acid group significantly improved PMNL motility and decreased ASO levels and reduced (although not to a significant extent) IgE levels and titres of antibodies to the respiratory viruses were observed.

Adolescent↗
PubMed1981

Immunological assessment of patients with rheumatoid arthritis--evaluation of the effects of propranolol.

Some humoral and cellular immune functions were evaluated in a group of 10 patients with rheumatoid arthritis before and after 3 months of treatment with the beta-blocking agent propranolol. Humoral parameters measured were serum immunoglobulins including IgE, auto-antibodies, C-reactive protein, total haemolytic complement activity and the complement components C3 and C4. Cellular functions assessed were polymorphonuclear leucocyte chemotaxis, phagocytosis and postphagocytic nitroblue tetrazolium reduction, hexose monophosphate shunt activity and myeloperoxidase-mediated iodination of ingested protein; lymphocyte transformation to the mitogens phytohaemagglutinin and concanavalin A was also investigated. No alteration of humoral factors and neutrophil functions was observed following propranolol administration (40 mg 3 times a day), but lymphocyte transformation was significantly increased. Improved lymphocyte function did not correlate with clinical improvement.

Adult↗
PubMed1981

In vitro and in vivo stimulation of neutrophil migration and lymphocyte transformation by thiamine related to inhibition of the peroxidase/H2O2/halide system.

The effects of thiamine on neutrophil functions and mitogen-induced lymphocyte transformation were investigated in vitro and in vivo in adult volunteers following the injection of 50 mg thiamine intramuscularly. Thiamine caused stimulation of neutrophil motility in vitro and in vivo and increased lymphocyte transformation in vivo. Enhancement of these functions was related to inhibition of neutrophil post-phagocytic iodination of Candida albicans by the MPO/H2O2/halide system. The horseradish peroxidase/-H2O2/125 I-mediated iodination of bovine serum albumin was also inhibited by thiamine concentrations which caused increased neutrophil motility. It was found that preincubation of neutrophils and lymphocytes with the horseradish peroxidase/H2O2/halide system caused considerable inhibition of the migratory and proliferative responses respectively. Inclusion of thiamine at concentrations which were found to inhibit the peroxidase/-H2O2/halide system protected the neutrophil migratory and lymphocyte proliferative responses from inactivation by this system. It is suggested that thiamine may cause increased neutrophil migration and lymphocyte transformation by protecting these cells from toxic oxidative products generated by the peroxidase/H2O2/halide system.

Adult↗
PubMed1980

The effect of ascorbate on cellular humoral immunity in asthmatic children.

Ten White children with bronchial asthma and exercise-induced bronchoconstriction were assessed immunologically before and 1, 3 and 6 months after the commencement of standard therapy supplemented with ascorbate 1 g/d. The tests of cellular immune function were neutrophil chemotaxis, phagocytosis and resting and stimulated nitroblue tetrazolium reduction, and lymphocyte mitogen-induced transformation. Humoral functions measured were secretory IgA, serum immunoglobulins, alpha 1-antitrypsin, C3, C4 and total haemolytic complement, antistreptolysin O (ASO) and C-reactive protein. Radio-allergosorbent testing to the common allergens Cynodon dactylon (grass), Dermatophagoides pteronyssinus (mite), house dust and cat epithelium was performed on each child before and 3 and 6 months after treatment. Two children had depressed neutrophil motility, 4 had depressed lymphocyte transformation, and 7 had elevated levels of ASO. These functions normalized after 6 months of ascorbate-supplemented therapy. Serum total IgE levels but not specific IgE levels were likewise reduced after 6 months of therapy. Reduced levels of serum alpha 1-antitrypsin were observed in 2 children, and remained unchanged throughout the study.

Antibody Formation↗
PubMed1980

[Evaluation of the drift of cercariae by a single daily sampling in the site of schistosomiasis transmission. Example of Guadeloupean sites of Schistosoma mansoni transmission (author's transl)].

Research on cercarian density in running water transmission sites of intestinal schistosomiasis in Guadeloupe has allowed the construction of a representative model of the rhythm of presence of Schistosoma mansoni cercariae. This model allows, with a single daily sampling between 11 a.m. and 2 p.m., the evaluation of the daily sum of hourly densities. We propose to measure the parasite component of the risk of contamination in a bilharzial site by the drift of cercariae expressed in cercariae/day. The drift of cercariae takes account of variations in cercarian density and of the flow of the channel. It expresses the daily quantity of cercariae available for human contamination.

Animals↗