Regulation of renal hemodynamics after protein feeding: effects of loop diuretics.

These studies were designed to test the hypothesis that the renal vasodilation and increased glomerular filtration rate (GFR) after a high-protein meal are mediated by the tubuloglomerular feedback (TGF) mechanism. In eight chronically instrumented conscious dogs, a meal of raw beef (10 g/kg) caused GFR to increase from 66 +/- 5 to 90 +/- 7 ml/min and effective renal plasma flow (ERPF) to increase from 191 +/- 25 to 281 +/- 24 ml/min, while plasma alpha-amino N levels rose from 4.0 +/- 0.1 to 7.3 +/- 0.6 mg/dl. On another day the dogs were given an infusion of furosemide to block TGF, and fluid and salt losses were continuously replaced. Furosemide alone caused GFR to increase in most animals, although the average change did not reach statistical significance, and ERPF increased by 31%. Sodium excretion rose from 15 +/- 5 to 2,390 +/- 280 mueq/min, and urine flow rose from 1.17 +/- 0.22 to 20.5 +/- 2.4 ml/min. Autoregulatory capability was also abolished (autoregulatory index = 0.87 +/- 0.09 compared with 0.19 +/- 0.05 before furosemide). However, there was no significant change in GFR and ERPF after a subsequent meat meal in dogs receiving furosemide. On another day, some of the dogs were given another loop diuretic, ethacrynic acid, which caused no change in GFR, whereas its effects on ERPF, sodium excretion, and urine output were similar to those of furosemide. There were also no changes in GFR or ERPF after a meat meal during ethacrynic acid administration, despite normal increases in plasma alpha-amino N.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro activities of norfloxacin and ciprofloxacin against Mycobacterium tuberculosis, M. avium complex, M. chelonei, M. fortuitum, and M. kansasii.

The activities of ciprofloxacin and norfloxacin against 100 mycobacteria isolates were studied in vitro by the 1% standard proportion method. Ciprofloxacin was more active against M. tuberculosis and M. fortuitum with MICs of 1.0 and 0.25 microgram/ml, respectively, against 90% of isolates; norfloxacin had MICs of 8.0 and 2.0 micrograms/ml, respectively, against 90% of isolates.

Mycobacteremia and the new blood culture systems.

Clinical and microbiologic aspects of mycobacteremia occurring in 11 patients are presented. Ten of the 11 patients were immunosuppressed. Disseminated disease was shown in 7 patients, transient bacteremia in 2, and endocarditis in 1. Blood cultures were positive in 11 blood culture systems. Newer blood culture systems appear to provide more rapid detection of mycobacteremia.

Comparison of a radiometric method (BACTEC) and conventional culture media for recovery of mycobacteria from smear-negative specimens.

The BACTEC system and three conventional media (Middlebrook 7H10, selective Middlebrook 7H11 [S7H11], and Lowenstein-Jensen [LJ] were compared for their mean recovery times and recovery rates of mycobacteria from acid-fast, smear-negative clinical specimens. Of the 71 smear-negative, culture-positive specimens recovered from 2,165 submitted smear-negative cultures, the BACTEC system detected 71.8%, compared with 88.7% for the conventional three-medium system. When media were individually compared, BACTEC medium (Middlebrook 7H12) was more successful in recovering mycobacteria (71.8%) than was LJ (62%), Middlebrook medium 7H10 (55.9%), or Middlebrook S7H11 medium (52.1%). Middlebrook 7H11 medium containing sodium selenate was also evaluated and did not increase the recovery rate or decrease the recovery time of mycobacterial species when compared with LJ, Middlebrook 7H10, S7H11, and 7H12 media. The mean detection time for the BACTEC system was less than that by conventional methods for the seven species of mycobacteria recovered. Detection times for Mycobacterium tuberculosis on the BACTEC system and conventional cultural systems were 13.7 and 26.3 days, respectively.

Identification of clinical isolates of mycobacteria with gas-liquid chromatography: a 10-month follow-up study.

Identification of routine mycobacterial isolates by gas-liquid chromatography profile analysis was performed on 335 strains received at the Mayo Clinic over a 10-month period. Comparison of identification by gas-liquid chromatography versus conventional biochemical profiles was made. The two methods agreed on the identification of 320 isolates, with gas-liquid chromatography profiling making eight errors and biochemical profiling making four errors. In three cases, discrepancies could not be resolved.

In vitro synergistic activity of ethambutol, isoniazid, kanamycin, rifampin, and streptomycin against Mycobacterium avium-intracellulare complex.

Strains of Mycobacterium avium-intracellulare complex often exhibit in vitro resistance to common antimycobacterial agents. Combinations of etambutol, isoniazid, kanamycin, rifampin, and streptomycin were tested to determine if synergism occurred. Ninety-six percent of the strains were susceptible to a combination of ethambutol and rifampin at concentrations attainable clinically. Other combinations of antimycobacterial agents inhibited 4 to 82% of the isolates tested.

Recovery of pathogenic fungi from clinical specimens submitted for mycobacteriological culture.

A total of 332 major pathogenic fungi were isolated from specimens cultured onto both fungal culture media and media used for culturing mycobacteria from January 1968 to June 1975. Only 72 (21.7%) fungi were recovered on media used for culturing mycobacteria. The effect of sodium hydroxide treatment was evaluated and shown to be detrimental to the recovery of fungi. It is recommended that clinical laboratories not rely on mycobacteriological cultures to recover fungal pathogens.