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Biomedical subjects

A C McDougall

Publications and source records attributed to A C McDougall.

At least 19 recordsLinked to original sources
PubMed1992

The allocation of leprosy patients into paucibacillary and multibacillary groups for multidrug therapy, taking into account the number of body areas affected by skin, or skin and nerve lesions.

In Nepal, the setting up and maintaining of reliable services for slit-skin smears has proven difficult. A clinical classification system for leprosy has therefore been developed to assist in the allocation of patients to either paucibacillary or multibacillary groups for the purpose of multiple drug therapy (MDT), using 9 body areas: head (1), arms (2), legs (2), trunk (4). Patients with more than two areas of the body affected are grouped as multibacillary (MB) and those with only one or two areas affected are paucibacillary (PB). Using a computer simulation model and the data of 53 patients registered at Green Pastures Hospital (GPH) in Pokhara and 703 field patients from the Western Region, different clinical classification systems were evaluated with regard to their sensitivity, specificity, and predictive value for MB or PB classification, as compared with the histological classification for the GPH cases and the bacteriological classification for the field patients. The sensitivity and specificity of the body area system in present use were 93% and 39%, respectively. The low specificity is due to MB overclassification. The sensitivity of the WHO classification system without skin smear facilities is 73% (the difference with the body area system is significant: p < 0.05, McNemar's test). Our histology findings confirm previous publications indicating that, while some borderline-tuberculoid (BT) patients may outwardly have a 'PB appearance' and be skin-smear negative, their nerve biopsy and sometimes skin biopsy may show a 'MB' picture. This is the first publication discussing a 'body area system' for the purpose described, including diagrams of the areas used. In Nepal it has proved easy to use and teach and its use may be justified in other control programmes which implement MDT, particularly if slit-skin smear services are unreliable or nonexistent.

Adolescent↗
PubMed1979

Dapsone.

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Dapsone↗
PubMed1979

The paranasal sinuses in lepromatous leprosy.

During the course of a larger study of patients with treated lepromatous leprosy attending a hospital in South India, sixteen patients with untreated disease presented with symptoms suggesting both intranasal and sinus involvement. Radiological abnormalities of the sinus were recorded in all sixteen patients and the results have been published separately. This paper describes the clinical and bacteriological findings, together with the results of histopathological examination of biopsies of sinus mucosa in two patients, in both of whom there was a histiocytic infiltrate, with acid-fast bacilli. In one of these biopsies, bacilli in the lamina propria were numerous; globi were common, and 20% of free-standing organisms were solid-staining. The significance of these findings is discussed with emphasis on the value of a full ear, nose and throat examination in all cases of leprosy, especially those with the lepromatous form. In this type of leprosy the upper respiratory tract tissues are clearly of importance for the lodgement and of multiplication of bacilli; it is possible that the paranasal air sinuses, with their large surface area, may contribute to the numbers of bacilli which are disseminated from the nose into the environment.

Body Temperature↗
PubMed1979

Untreated lepromatous leprosy: histopathological findings in cutaneous blood vessels.

Skin biopsies from 100 patients with untreated lepromatous leprosy from Malaysia, India, Africa, and South America were examined with particular regard to pathological changes in intima, media, or adventitia of blood vessels and to the presence of leprosy bacilli in these layers. Bacilli were found in capillaries, venules, or arterioles in all cases, and in many instances they were present in endothelial lining cells or smooth muscle in large masses (globi). In several cases, solid-staining bacilli in endothelial lining cells were especially prominent. The findings are discussed in relation to a) the continuous bacteremia of lepromatous leprosy, b) the role of endothelial cells in phagocytosis, c) smooth muscle cells of the media as a site in which bacilli may persist, and d) the transmission of human leprosy by biting arthropods.

Blood Vessels↗
PubMed1978

Ocular histopathology in animals experimentally infected with Mycobacterium leprae and M. lepraemurium. 1. Mycobacterium leprae and M. lepraemurium infections in the mouse. 2. Mycobacterium leprae infections in the 9-banded armadillo (Dasypus novemcinctus L.).

At varying periods of time following the successful establishment of systemic infections with Mycobacterium leprae or M. lepraemurium in the mouse and the nine-banded armadillo eyes were examined by light microscopy. Inoculation of bacilli was by the intravenous or intraperitoneal route or directly into the hind footpads; eyes were not directly inoculated in this study. During periods of up to 3 years under laboratory conditions no animal showed evidence of impaired vision or blindness, and the external appearance of both eyes was normal. The ocular histopathology and the sites of accumulation of bacilli are described. In immunologically normal mice infected with M. lepraemurium bacilli were much commoner in extraorbital tissues, but they were, nevertheless, found in various tissues within the orbit, including the ciliary body and sclera. In immunologically normal mice (and one rat) injected with M. leprae of human origin no bacilli were found in the eye, but in mice immunologically depressed by thymectomy and total body irradiation considerable numbers of bacilli were present in the iris and ciliary body and also in the limbal cornea. In the armadillo bacilli were found in large numbers in virtually all tissues except the lens, retina, optic nerve, and aqueous and vitreous humours, but the uveal tract was heavily involved. Findings are discussed in relation to the great frequency of ocular involvement and the importance of immune-complex disease in patients with lepromatous leprosy, and to factors wihch may favour the localisation and multiplication of Mycobacterium leprae in the eye.

Animals↗
PubMed1978

Peripheral nerve biopsies in the diagnosis of leprosy in Aboriginal patients from the Northern Territory of Australia.

In the 12 years from 1964 to 1976, 171 peripheral nerve biopsies were taken from 81 Aboriginal patients in the Northern Territory of Australia, in whom a diagnosis of leprosy was either known or strongly suspected. Sixty-eight biopsy samples were from 19 patients known to have leprosy, and who were under assessment for nerve grafting, results of which have already been published. We describe here the histopathological findings in the remaining 62 patients, in whom a diagnosis of leprosy was suspected on clinical grounds, backed in many cases by abnormalities of nerve conduction. Forty-one patients (66%) had abnormal histopathological findings in the nerve biopsy sample, 19 (31%) showing definite evidence of leprosy. Several patients with enlarged peripheral nerves, in whom the biopsy findings did not confine leprosy, remain under observation; their future investigation will include lymphocyte transformation tests and testing with refined lepromin, together with repeat nerve biopsy, where ethical and feasible. The clinical and epidemiological data suggest that a previous, and perhaps self-healing, form of leprosy may account for the neurological findings.

Abscess↗
PubMed1978

Experimental lepromatous leprosy in the white-handed gibbon (Hylobatus lar): successful inoculation with leprosy bacilli of human origin.

Leprosy bacilli of human origin were inoculated into a white-handed gibbon by the i.v. and i.p. routes, and also locally into ears, testis and around an ulnar nerve. The animal was observed closely during a period of nearly 15 years and did not exhibit any clinical evidence of cutaneous or neurological disease. At death, a wide range of tissues was taken for bacterial counts and histological examination, and a disseminated and progressive infection was demonstrated. Acid-fast bacilli were found in many sites; their morphological appearance distribution in nerves, and pattern of multiplication in mouse foot-pads, and also the presence of anti-mycobacterial antibody in the serum and the absence of specific lymphocyte transformation were all in keeping with an infection by Mycobacterium leprae, at an early lepromatous stage. This is probably the first fully documented report of experimental lepromatous infection in a primate. The findings are discussed in relation to the long incubation period of le promatous leprosy and the difficulties of diagnosing the disease at an early stage in man.

Animals↗
PubMed1978

Integrated leprosy control in Guyana.

Guyana instituted a "find and treat" leprosy program in 1971 that made use of existing out-patient facilities and staff. The program, based on an integrated domiciliary approach to diagnosis, treatment, and examination of contacts, has proved successful. This article describes development of the program and discusses the prospects for control and eventual eradication of leprosy in Guyana.

Delivery of Health Care↗