Measurement of atomic lifetimes with a mode-locked laser.

We present a new technique for measuring atomic lifetimes with a mode-locked laser. A single laser pulse excites the atoms and a subsequent frequency-doubled pulse ionizes the excited-state atoms. The ions are collected and counted. The measurement is repeated using excitation and detection pulses with different time separations, which determines the excited-state decay rate. We demonstrated this technique for the 6P(3/2) state of cesium. The measured lifetime was 30.5 ns and had a statistical uncertainty of 0.1 ns. Systematic effects limited the overall experimental uncertainty to approximately 0.6 ns in this initial experiment.

Short-course chemotherapy for pulmonary disease caused by Mycobacterium kansasii.

Forty patients with pulmonary disease caused by Mycobacterium kansasii were treated initially with rifampin, isoniazid, and ethambutol daily for 12 months, and with streptomycin twice weekly for the first 3 months. Postchemotherapy follow-up examinations have ranged from 6 to 68 months, with an average of 31 months. One of the 40 patients (2.5%) relapsed 6 months after completion of chemotherapy. In vitro susceptibility of the mycobacteria to the drugs used, extent of disease, and/or the coexistence of other diseases did not seem to influence the outcome. This 12-month chemotherapy regimen is considered to be sufficient for the initial treatment of pulmonary disease caused by M. kansasii.

Factors relating to recurrence of chronic pulmonary histoplasmosis following treatment with amphotericin B.

A retrospective analysis was made of cases of Chronic Pulmonary Histoplasmosis during the admission in which patients received amphotericin B to determine if there were features related to recurrence of the disease. There was significance at the p less than or equal to 0.05 level in that the nonrecurrent cases tended to have a lower initial complement fixation titers using mycelial antigen; had initial complement fixation tests which were likely to result in no reaction using either mycelial or yeast antigen; and had more rapid drops in the complement fixation values using the yeast antigen. Although the present evaluation does not suggest an absolute minimum effective dose of amphotericin B, it would seem plausible to administer a course of at least 2300 mg if the initial complement fixation test was nonreactive but if the drug was tolerated well by the patient and the initial complement fixation test was reactive, the goal should be at least 2500 mg.

Chemotherapy for pulmonary disease due to Mycobacterium kansasii: efficacies of some individual drugs.

An evaluation of chemotherapy was made for 256 patients with pulmonary infection due to Mycobacterium kansasii. Studies of in vitro resistance of M. kansasii and Mycobacterium tuberculosis to various drugs revealed important differences between the two species that should be considered when planning chemotherapy. Partial or no in vitro resistance to 1 microgram of isoniazid/ml did not adversely affect the time required for conversion of sputum from positive to negative, whereas complete resistance to isoniazid had a statistically significant (P less than 0.001) adverse effect. All of the 115 patients who received treatment that included rifampin (initial and retreatment) had sputum conversion within four months. However, for regimens that did not include rifampin, 127 (90%) of 141 patients had conversion within four months (P less than 0.01). After completion of chemotherapy that included rifampin, there were no relapses among 64 patients, but after therapy without rifampin, four (7%) of 59 patients relapsed. The greater efficacy of the regimens that included rifampin may be due at least partially to the fact that more drugs were administered than in regimens that did not include rifampin. The use of p-aminosalicylic acid seems unwarranted in the treatment of disease due to M. kansasii. Since rifampin may be the most potent drug for treatment of this disease, the recommended combinations for initial treatment are (l) rifampin, streptomycin, isoniazid, and ethambutol, or (2) rifampin and two other drugs to which the organism is sensitive.

Elimination of Mycobacterium intracellulare from sputum after bronchial hygiene.

Three cases are presented, each of which had more than 20 positive cultures of sputum for Mycobacterium intracellulare, infiltrations, and a history of bronchiectasis. Two had complete and the third nearly complete, sputum conversion during a program of bronchial hygiene without chemotherapy. It is probable that these cases were only noninvasive colonizations in previously diseases lungs. Recommendations are given for a therapeutic approach in such cases.

A demographic study of disease due to Mycobacterium kansasii or M intracellulare-avium in Texas.

The number of patients reported th have disease due to Mycobacterium kansasii or M intracellulare-avium has increased in Texas from January 1967 to December 1976, in contrast to a decrease in tuberculosis. Presented is an analysis of 1,409 patients infected with M kansasii and 706 patients infected with M intracellulare-avium. The former group clustered in urban areas with more than twice the incidence compared to nonurban areas (P less than 0.001). The latter group was more diffusely distributed with approximately twice the incidence in nonurban areas compared to urban areas (P less than 0.001). The average age of the group infected with M kansasii was 50 years and of the group infected with M intracellulare-avium 58 years. In patients infected with M kansasii only, the average age was significantly higher for men than women. There was a male predominance in both groups, ie, 3:1 in M kansasii and 2:1 in M intracellulare-avium. Persons with Spanish surnames had a low incidence of disease due to M kansasii. No other racial or ethnic association was noted. The various factors involved in determining the atypical mycobacterial diseases are discussed.

The value of the skin test and complement fixation test in the diagnosis of chronic pulmonary histoplasmosis.

Histoplasmin skin test results in patients with chronic pulmonary histoplasmosis from Missouri and Texas were compared to results in a previous study of U.S. Navy recruits. When consideration was given to geographic areas from which persons from each group were admitted to the study, it was found that the recruits were as likely to have a positive skin test as were those with the disease. In a similar manner, the Texas histoplasmosis patients were compared to groups of patients from that state with chronic obstructive pulmonary disease and with pulmonary tuberculosis. Again, no significant differences were found. It was concluded that the histoplasmin skin test is not of value in the diagnosis of chronic pulmonary histoplasmosis. Histoplasmosis complement fixation test data from the chronic pulmonary histoplasmosis group were compared to data from the chronic obstructive pulmonary disease and pulmonary tuberculosis groups. The usefulness of the complement fixation test in chronic pulmonary histoplasmosis is limited, as with any test, by false-positive and false-negative reactions. A decision theory method was used to define the limits of usefulness.