Virulence of tubercle bacilli isolated from patients with tuberculosis in Bangalore, India.

This is a study of the virulence of cultures of Mycobacterium tuberculosis isolated from pulmonary and extrapulmonary forms of tuberculosis in patients living in or near Bangalore, India. The findings are as follows: 1. The percentage of cultures recovered from cases of pulmonary tuberculosis in Bangalore classified as being of low, moderate, and high virulence, was the same as that reported by Mitchison et al., in 1960 for isolates obtained from patients in Madras, India. 2. The distribution of the root index of virulence (RIV) of isolates from patients living in the city of Bangalore was significantly different (p less than 0.05) from that of isolates from patients living in rural Bangalore. 3. Even though the number of cultures classified as high virulent was significantly greater in isolates from patients with tuberculosis meningitis compared with those from patients with pulmonary tuberculosis, the data show that 36% of the isolates from the meningitis group were classified as low virulent.

Neuromuscular transmission in thyrotoxicosis.

The occurrence of thyrotoxicosis in myasthenia gravis is estimated as 5.3% (Osserman et al. 1967) but the incidence of myasthenia in the course of thyrotoxicosis is only 0.2% (Simpson 1968). The association between these two diseases is not a chance one and there are two possible basic mechanisms viz. the action of thyroid hormone on the neuromuscular junction or the existence of a cause common to both. The fatigability seen clinically in thyrotoxic myopathy could be partly attributed to myasthenia. With these possibilities in mind, a search for electromyographic stigmata of latent myasthenia was done on 48 consecutive cases of hyperthyroidism who also had chronic myopathy by performing repeated nerve stimulation. Eight cases had abnormal neuromuscular transmission as in myasthenia gravis and one of these cases later developed clinical myasthenia involving the ocular muscles. Three other cases showed abnormal facilitation as in the Eaton-Lambert syndrome.

Thyrotoxic myopathy: a clinical and quantitative analytic electromyographic study.

The clinical entity of chronic thyrotoxic myopathy was considered rare by Waldenström in 1945. Forty eight consecutive patients with thyrotoxicosis were studied clinically and by electromyography for muscle involvement. Quantitative electromyographic techniques were used to analyse both the electromyographic activity of the muscle at a standard tension and also the single motor potential obtained in isolation at minimal effort. The interference pattern was described in simple numerical terms such as the number of potential changes/s and the mean amplitude. All cases that were thyrotoxic (both clinically and on thyroid function tests) showed the changes of myopathy on electromyography, though only 68% of the cases showed clinical myopathy consisting of muscle weakness and/or atrophy.

A case of myasthenia gravis with thyrotoxicosis treated by combined subtotal thyroidectomy and total thymectomy.

Thyrotoxicosis occurring in conjunction with myasthenia gravis is rare. The usual treatment consists of medical control of the thyrotoxicosis, then thymectomy and later subtotal thyroidectomy. The case reported here concerns a 19-year-old girl who had surgical treatment for both lesions on the same occasion. With proper medical preparation, modern anaesthesia and respiratory care, the surgical treatment of both lesions can be accomplished in one stage.

Some operational factors influencing the utility of culture examination in the diagnosis of pulmonary tuberculosis.

Culture examination is technically superior to direct microscopy in the diagnosis of pulmonary tuberculosis, but its practicability and relative importance in various phases of national tuberculosis control programmes in developing countries must be studied before culture facilities are provided on a large scale.Some operational factors affecting the efficacy of the culture method have been analysed in four studies conducted by the National Tuberculosis Institute, Bangalore. The results showed that an interval of up to 7 days between collection of specimens in the field and culture in the laboratory did not affect the yield of positive cultures, even though the specimens were stored and transported under field conditions. A higher proportion of positive cases was detected by culture than by direct microscopy, but the magnitude of the additional yield was dependent upon the procedure for selecting persons for sputum examination. In service programmes restricted to persons with symptoms who voluntarily attend diagnostic centres, the increased yield is too small to justify the introduction of culture examination. The method is substantially rewarding, however, in the evaluation of national control programmes, in changes of drug regimen consequent on altered bacteriological status, and in mass programmes for the early detection of infectious cases.