Remodelaçäo cirúrgica da valva aórtica / Surgical remodeling of the aortic valve

OBJETIVO: Os autores analisam os resultados por eles obtidos com a utilizaçäo de técnica específica para a preservaçäo da valva aórtica. CASUíSTICA E MÉTODOS: Esse método consiste no emprego habitual da circulaçäo extracorpórea com uso de hipotermia moderada e infusäo de soluçäo cardioplégica nos óstios coronários. Realiza-se ressecçäo da válvula näo coronariana e une-se as comissuras correspondentes utilizando-se fio de Mersilene 2-0 ancorado em feltro de teflon, tornando a valva "bivalvulada". Procede-se por fim à aortorrafia convencional. Foram operados 15 pacientes, 9 do sexo masculino. A idade variou entre 12 e 78 anos. Quatro pacientes tinham diagnóstico de insuficiência aórtica isolada, 2 com dupla disfunçäo aórtica associada à insuficiência coronária, 2 com doença da aorta ascendente, 4 com insuficiência aórtica e mitral, 1 com dupla disfunçäo aórtica e mitral, e 2 com insuficiência aórtica e insuficiência coronária. RESULTADOS: Em 12 pacientes näo houve insuficiência aórtica residual pós-operatória, e em 3 identificou-se insuficiência aórtica leve ou moderada. Três pacientes foram reoperados no pós-operatório tardio devido a insuficiência aórtica, tendo sido substituída a valva aórtica em 2. Quatro pacientes foram submetidos a estudo hemodinâmico e em 1 deles havia gradiente supravalvar de 20 mmHg. Nos outros 3 pacientes, o gradiente sistólico transvalvar foi de 0, 9 e 12 mmHg, respectivamente. Os 11 pacientes restantes foram avaliados somente através de ecocardiografia, a qual näo demonstrou estenose. Näo houve óbito imediato e houve 1 óbito tardio, após reoperaçäo. Quatorze pacientes tiveram melhora da classe funcional, tanto imediata quanto tardiamente, e foram acompanhados durante período entre 30 dias e 24 meses, encontrando-se em classe funcional I ou II (NYHA). CONCLUSÄO: Os autores acreditam que o método seja uma alternativa para o tratamento cirúrgico conservador da doença valvar aórtica

Evaluation of the BACTEC radiometric method in the early diagnosis of tuberculosis.

A comparison of the BACTEC radiometric method with the conventional culture and drug susceptibility testing methods on isolates from clinical specimens in pulmonary and extrapulmonary tuberculosis, childhood TB and TB in HIV-infected individuals was undertaken. In the case of pulmonary TB, the rate of isolation of positive cultures was significantly faster with the BACTEC method, with 87 per cent of the positives being obtained by 7 days, and 96 per cent by 14 days. However, while there was no difference in the total number of positive cultures by the two methods in smear positive pulmonary tuberculosis, in smear negative pulmonary TB, the BACTEC method yielded more number of positive cultures. In extrapulmonary TB, HIV-TB and childhood TB, although the BACTEC method did not yield additional positives, the detection of positives was considerably faster than by the conventional methods, in which the degree of growth was also scanty. The agreement in drug susceptibility tests was 94 per cent for streptomycin and isoniazid, 99 per cent for rifampicin and 91 per cent for ethambutol. Further, most of the drug susceptibility test results became available within 8 days by the BACTEC method. By facilitating early diagnosis, the BACTEC method may prove to be cost effective in a population with a high prevalence of tuberculosis, particularly in the extrapulmonary and paucibacillary forms of the disease.

Action of metronidazole in combination with isoniazid & rifampicin on persisting organisms in experimental murine tuberculosis.

To study the activity of metronidazole on persisting tubercle bacilli, BALB/c mice were infected with Mycobacterium tuberculosis and, after 14 days, treated with isoniazid (H) or rifampicin (R) or isoniazid + rifampicin (HR) for 2 months. An untreated group and a group treated with metronidazole (M) alone served as controls. At the end of 2 months, M was added to the H, R, and HR regimen in half the mice, and the treatment was continued for 1 more month in all mice. At the end of treatment, no viable organisms were detected in the lung or spleen of mice treated with HR or HRM regimens. In contrast, compared to the mice treated with R alone, the log10 colony forming units (cfu) of mice treated with RM were lower by 1.84 and 0.52 in the lung and spleen, respectively. Similarly, compared to the H group, the log10 cfu were lower by 0.67 in the spleen of mice treated with HM, and no additional effect due to M was seen in the lung. Three months after stopping treatment, viable organisms were isolated from both the organs of all the groups. However, the log10 cfu in the lung and spleen for the groups with metronidazole were below the log10 cfu for the respective single or 2 drug groups, except the log10 cfu in the lung for the RM group. These findings suggest that metronidazole, given with bactericidal drugs such as rifampicin and isoniazid may be of value in eliminating persisting tubercle bacilli, but further studies are warranted.

Immune response & modulation of immune response induced in the guinea-pigs by Mycobacterium avium complex (MAC) & M. fortuitum complex isolates from different sources in the south Indian BCG trial area.

A total of 139 guineapigs were used to study the immune response and its modulation induced by Mycobacterium avium complex (MAC) and M. fortuitum complex strains obtained from different sources in the south Indian BCG trial area. The guineapigs were divided into groups and some were directly sensitised/immunised with different MAC strains. M. fortuitum complex strain or BCG and others were sensitised with MAC or M. fortuitum complex and then immunised with BCG. The resulting delayed type hypersensitivity (DTH) response in the different groups of guineapigs was studied by skin tests using PPD-RT23 and PPD-B, and protective response was studied by challenging the guineapigs with a south Indian low virulent strain of M. tuberculosis and enumerating the bacilli in spleen at different points of time. The 3 strains of MAC induced similar low levels of DTH to PPD-RT23 but much higher and varying levels of DTH to PPD-B. MAC strains from soil and sputum induced different levels of immune modulation during subsequent immunisation with BCG on the DTH response to PPD-RT23 and PPD-B. At 2 wk after challenge, 23.8, 81 and 90.5 per cent protection was induced by the standard strain, soil isolate and sputum isolate of MAC, respectively, while 33.3 per cent protection was induced by the M. fortuitum complex strain compared to the protection induced by BCG alone. Prior exposure to MAC or M. fortuitum complex did not have any modulatory effect on the protective immunity due to BCG at this time point. However, at 6 wk after challenge, while the guineapigs immunised with BCG were protected, modulation of the protective response resulting from BCG was observed in the guineapigs sensitised with MAC and M. fortuitum from soil.

Early bactericidal action of pulsed exposure to rifampicin, ethambutol, isoniazid & pyrazinamide in pulmonary tuberculosis patients.

The bactericidal action of two therapeutic regimens on Mycobacterium tuberculosis was assessed by viable counts in serial sputum samples in 49 pulmonary tuberculosis patients being treated with rifampicin (R), ethambutol (Emb), isoniazid (I) and pyrazinamide (Z) together in a single dose thrice weekly (REmbIZ3) or with REmb and IZ on alternate days (REmb3IZ3alt). In both groups of patients, there was a significant reduction (P < or = 0.02) in the colony forming units (cfu) of M. tuberculosis per ml of sputum during the first two days of treatment itself. This early bactericidal action (EBA) as well as the reduction in counts during the subsequent days of treatment were similar (P > 0.2) for both REmbIZ3 and REmb3IZ3alt regimens indicating that splitting up REmbIZ into REmb on one day and IZ on the next day in short course chemotherapy (SCC) regimens may not affect the bactericidal action of the regimens.

Protective response in guinea pigs exposed to Mycobacterium aviumintracellulare/M. scrofulaceum, BCG & south Indian isolates of M. tuberculosis.

The protective immunity resulting from exposure to nontuberculous mycobacteria (NTM), BCG and virulent mycobacteria in different sequences was studied in the guinea pig model employing strains prevalent in the south Indian BCG trial area and time kinetics to observe the immuno-modulation. The findings suggest that during the early course of challenge infection in guinea pigs there was no interference with the immunity due to BCG, by prior exposure to NTM. In the animals sensitised with M. avium intracellulare before immunisation, the challenge infection was localised and confined to the site of inoculation, and only a few organisms reached the spleen. However, at the later stages of the infection, as seen by the spleen viable counts at 12 wk, it appeared that the barrier at the localised site of infection may not be intact in the animals with prior exposure to NTM, and a few organisms disseminate to the spleen.

In vitro experiments with Centella asiatica: investigation to elucidate the effect of an indigenously prepared powder of this plant on the acid-fastness and viability of M. tuberculosis.

The herb Centella asiatica (Linn.), found throughout India, is acclaimed to have medicinal properties and has been used in leprosy patients from very early times. It is considered that the active compound of this herb, called asiaticoside, probably acts on the waxy covering of M. leprae. The in vitro effect of an indigenously produced dry powder of Centella asiatica (CA) on the acid-fastness and viability of M. tuberculosis was investigated in the present study. The results indicate that CA may not have any direct action on the acid-fastness or viability of M.tuberculosis H37Rv in vitro. Further studies using purified asiaticoside of the plant or in vivo studies are required.

Bactericidal action of pulsed exposure to rifampicin, ethambutol, isoniazid & pyrazinamide on Mycobacterium tuberculosis in vitro.

The bactericidal action of pulsed exposure to rifampicin (R), ethambutol (Emb), isoniazid (I) and pyrazinamide (Z) together on alternate days (REmbIZ) and as REmb and IZ separately on alternate days (REmb/IZ) on M.tuberculosis H37Rv, two isolates of M.tuberculosis sensitive to these drugs, as well as four isolates resistant to one or more drugs, was studied using an in vitro method. The experimental duration was 6 days. REmbIZ and REmb/IZ appeared to have equally good bactericidal action on M.tuberculosis strains in the in vitro system. The results suggest that splitting REmbIZ into REmb and IZ on alternate days in short course chemotherapy regimens for tuberculosis may not affect the bactericidal action of the regimens.

Observations on the cultivation of M. leprae and M. tuberculosis in medium 'V' and 'V 1'.

Skin scrapings from five different active sites were collected from 14 leprosy patients and inoculated into medium V. Skin scrapings from three leprosy patients were inoculated into medium V 1. All the cultures were incubated at 8-10 degrees C. M. tuberculosis H37Rv, pretreatment isolates and streptomycin resistant strains were inoculated into medium V, with and without antibiotics, and incubated at 8-10 degrees C as well as 37 degrees C. Smears were made from the M. leprae and M. tuberculosis cultures at 0 hours and at different time points. The number of bacilli in the smears were counted. There was no increase in the number of M. leprae or M. tuberculosis in any of the cultures.