Search PubMed⌕ Search

Biomedical subjects

J A Merchant

Publications and source records attributed to J A Merchant.

At least 73 records · Page 4Linked to original sources
PubMed1980

Enhanced viral interferon induction by the mineral wollastonite.

The in vitro activity of the fibrous mineral wollastonite (CaSiO3) on the interferon system was investigated. Wollastonite enhanced the induction of interferon by influenza virus in mammalian (LLC-MK2) cell monolayers but the mineral per se did not induce interferon. The magnitude of enhanced interferon induction was dependent on mineral concentration, particle size, and its time and sequence of addition onto cell monolayers. A "synergistic effect" on viral induction of interferon was noted when cell cultures were interferon-primed and then treated with wollastonite. Interferon yields were significantly higher than those obtained by the use of either the primer or wollastonite alone. That influenza virus multiplied in wollastonite-treated cells to a level that was sevenfold less than that in normal cells was associated with increased interferon production. The ability of interferon to confer antiviral cellular resistance was not impaired by wollastonite. The findings of this study suggest that the incorporation of wollastonite in appropriate interferon inducer-host cell systems may be useful for augmenting interferon production.

Animals↗
PubMed1978

The effect of sodium cromoglycate, beclomethasone diproprionate and salbutamol on the ventilatory response to cotton dust in mill workers.

A double-blind placebo controlled study of sodium cromoglycate, beclomethasone dipropionate and salbutamol by inhalation was designed to test their effect on respiratory symptoms and changes in ventilatory capacity in cotton mill workers. All three drugs showed some beneficial effect. Salbutamol was the most effective drug studied, in all groups of workers. Beclomethasone dipropionate was also significantly effective particularly in workers with byssinosis or exertional dyspnoea. Sodium cromoglycate was the least effective of the three. Possible mechanisms of action of these drugs are described.

Adult↗
PubMed1978

Lymphocyte responses to phytohaemagglutinin in patients with asbestosis and pleural mesothelioma.

Quantitative impairment of lymphocyte responses to phytohaemagglutinin (PHA) has been demonstrated in six (21%) out of twenty-eight patients with asbestos-associated pulmonary fibrosis, in comparison with a group of unexposed normal controls. The impairment tended to occur in patients with fairly severe fibrosis, comparatively short duration of exposure to asbestos dust and with increases in serum immunoglobulin levels. One patient with asbestosis and an associated bronchial carcinoma also had depressed lymphocyte responses to PHA. These findings suggest a relationship between defective T-lymphocyte function and the fibrotic response in asbestosis. Whether it is also linked with the development of lung cancer, occurring either before or at a pre-clinical stage of tumour growth, and is of value in identifying patients especially at risk should now be explored in longitudinal studies. However, eight out of ten patients with asbestos-associated pleural mesothelioma and without lung fibrosis showed no evidence of impaired cellular immunity, either by in vitro testing with PHA or by vivo delayed hypersensitivity skin testing, indicating that impaired T-lymphocyte function is unlikely to be a common finding in all types of asbestos-associated malignancy.

Adult↗
PubMed1975

The HL-A system in asbestos workers.

In a study of the HL-A system in 56 selected asbestos workers referred to the Pneumoconiosis Medical Panel with definite or suspected asbestosis, the W 27 antigen was found more often than among a control population. Six of the 10 asbestos workers with the W 27 antigen had definite radiographic evidence of asbestosis compared to 13 out of 46 without the W 27 antigen. These observations, if confirmed, suggest that the W 27 antigen may provide a useful marker of an enhanced susceptibility to the tissue-damaging effects of asbestos dust.

Adult↗
PubMed1975

Responses to cotton dust.

Twelve cotton textile workers were studied: (1) to compare standard measures of volume and expiratory flow, maximal expiratory flow volume (MEFV) curves, closing volume (CV), and closing capacity (CC) in detection of airway narrowing with cotton dust exposure; (2) to evaluate the response of arterial blood gases to exposure; (3) to measure changes in leukocytes in peripheral blood and airway secretions; and (4) to assess the temporal relationships and correlations between measures. Change in expiratory flow (FEV) most consistently and significantly discriminated between the control and cotton dust exposures. Vmax50%FVC was a more sensitive indicator, but variance was increased proportionately. CV and CC changed inconsistently with relatively large variances. The PaO-2 decreased overall and two subjects had large decrements. Peripheral blood and polymorphonuclear cell counts increased with exposure to cotton dust and polymorphonuclear leukocytes were recruited to the nasal mucosa. Chest tightness and decreased flow were temporally correlated with leukocyte recruitment that may be important in respiratory disease among cotton textile workers and therefore deserves further investigation.

Adult↗