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Biomedical subjects

B W Allen

Publications and source records attributed to B W Allen.

54 records · Page 3Linked to original sources
PubMed1980

Quality control in tuberculosis bacteriology. 1. Laboratory studies on isolated positive cultures and the efficiency of direct smear examination.

Sputum specimens unlikely to contain M. tuberculosis or specimens artificially created as methylcellulose/egg solution were autoclaved and distributed in batches together with sputum specimens containing viable M. tuberculosis marked with an unusual drug-sensitivity pattern. These specimens were prepared in 1 East African laboratory, divided into aliquots and examined by direct smear and culture in 3 East African laboratories. Independent batches were also prepared and cultured in London. Scanty colonies of M. tuberculosis, always with the characteristic marker sensitivity pattern, were obtained from a proportion of the autoclaved specimens, ranging from 0% of 825 specimens in London to 1.3% of 2165 specimens in Kampala. Transfer of bacilli from positive to negative specimens could therefore account for some of the isolated positive cultures that occur in clinical trials. The occurrence of transfer seemed to be related more to the quality of the technician than to the detail of the technical methods. The African laboratories could be graded in their overall efficiency in smear and culture examination.

Africa, Eastern↗
PubMed1980

Inhibitory effect of rubber on the growth of M. tuberculosis.

Rubber liners used in screw-cap bottles in Hong Kong were found to inhibit the growth of M. tuberculosis in culture media but not to exert any inhibitory effect on the bacilli in sputum. The British Standard for testing rubber used in transfusion equipment (BS: 2463) does not detect the inhibitory effect. It is recommended that rubber liners in the caps of bottles used for growing M. tuberculosis should be tested for cytotoxicity by a modification of the method described in British Standard 5213 or by the simple bacteriological tests described in this report.

Culture Media↗
PubMed1978

The correlation of bacteriophage types of Mycobacterium tuberculosis with guinea-pig virulence and in vitro-indicators of virulence.

Among 58 isoniazid-sensitive strains of Mycobacterium tuberculosis from India, Burma and East Africa, 23 were of phage type A, 31 of type I (intermediate), 4 of type B and none of type C. Type I strains differed from type A strains in being attenuated in the guinea-pig, susceptible to H2O2, sensitive to thiophen-2-carboxylic acid hydrazide and resistant to thiacetazone and p-aminosalicylic acid; the content of strongly acidic lipids and of sulphatide lipids was low and the attenuation indicator lipid was present. The pattern of results with the type B strains did not correspond to the patterns for types A or I. Strains of type I appear to be a distinct group within the species M. tuberculosis.

Aminosalicylic Acid↗
PubMed1977

Evaluation of a serological test for tuberculosis.

The agglutination test of Nicholls was found to be ineffective in diagnosing active tuberculosis. A positive result (titre of 1/125 or more) was found in the serum of 74 (70%) out of 105 patients with newly diagnosed, smear-positive pulmonary tuberculosis; 61 (62%) out of 98 healthy family contacts; and 19 (63%) out of 30 patients with non-tuberculous conditions. These findings were not due to faulty technique since the results obtained at Hammersmith were similar to those obtained by Nicholls's laboratory in the same serum samples. Twenty-seven of the tuberculous patients who had a negative result before treatment were retested two months after the start of chemotherapy but showed no evidence of a rising titre.

Agglutination Tests↗
PubMed1977

Comparison of strains of Mycobacterium tuberculosis from British, Ugandan and Asian immigrant patients: a study in bacteriophage typing, susceptibility to hydrogen peroxide and sensitivity to thiophen-2-carbonic acid hydrazide.

Strains of Mycobacterium tuberculosis were obtained from 65 patients with pulmonary tuberculosis resident in Uganda, and from pulmonary and extrapulmonary tuberculosis in 42 British patients of European ethnic stock and in 67 Asian immigrants, often from Uganda, resident in Britain. The bacteriophage-type patterns of the African, British and Asian strains were different. The pattern for the Asian strains resembled that found previously in patients from South India, suggesting that there has been little interchange of organisms between the Asian community and the African and British communities alongside whom they have lived. The patterns for pulmonary and extra-pulmonary tuberculosis were similar. Strains of bacteriophage type 1, mainly obtained from Asians, were characterized by a greater susceptibility to the bactericidal activity of hydrogen-peroxide and/or a greater sensitivity to thiophen-2-carbonic acid hydrazide than strains of other types.

Asia↗
PubMed1976

Comparison of machine and manual staining of direct smears for acid-fast bacilli by fluorescence microscopy.

Comparisons were made in Lusaka and in London between manual staining and staining in an automatic machine with auramine-phenol of direct smears of sputum and other types of specimen for acid-fast bacilli. No evidence was obtained of carry-over of acid-fast bacilli from positive to negative smears during machine staining. There was improved contrast between bacilli and the background in smears prepared with the machine.

Benzophenoneidum↗
PubMed1975

The penetration of dapsone, rifampicin, isoniazid and pyrazinamide into peripheral nerves.

1 Dapsone, rifampicin, isoniazid and pyrazinamide were shown to penetrate readily into the sciatic nerves of the dog and sheep. 2 These findings suggest that the continued persistence of viable drug-sensitive leprosy bacilli in the peripheral nerves of patients treated for long periods with either dapsone or rifampicin is not due to inadequate intraneural drug penetration.

Animals↗
PubMed1974

Assay of rifampicin in serum.

Two methods for the assay of rifampicin in serum are described. The first is a conventional plate diffusion method, measuring concentrations down to 0.02 mug/ml, and the second a chemical extraction followed by measurement of the inhibition of uptake of (14)C-uridine by Staphylococcus aureus, which estimates in the range of 0.02 to 0.001 mug/ml. The methods were used to measure serum concentrations in man following doses of about 1050 mg and 75 mg rifampicin.

Agar↗
PubMed1973

Selective media in the isolation of tubercle bacilli from tissues.

Direct culture on Lowenstein-Jensen slopes and on three media made selective for tubercle bacilli by the addition of four antibacterial agents was compared with guinea-pig inoculation on 490 tissue specimens. Tubercle bacilli were obtained from 15 specimens by culture and 14 by guinea-pig inoculation; only one specimen was positive by guinea-pig and not by culture. The most efficient culture medium was a selective 7H11 slope. Routine guinea-pig inoculation has been replaced by a wider range of culture procedures.

Amphotericin B↗