Inhibition by acetohydroxamic acid of human mucosal and faecal urease-specific activity

Inhibition of proliferation and differentiation of mouse erythroleukemia cells by hydroxamic acids

The effect of several hydroxamic acids on cell growth and differentiation was studied in vitro in cultures of Friend erythroleukemia cells, line F4-6. Terminal differentiation in F4-6 cells can be induced by exposure to a variety of structurally unrelated compounds or to conditions which inhibit cell growth. Hydroxamic acids do not induce erythroid differentiation but interfere with both cell growth of F4-6 cells and the induction of differentiation by DMSO in these cells. DMSO-induced terminal differentiation is inhibited even when F4-6 cells are pretreated for 24 h with hydroxamates followed by removal of the hydroxamates and transfer to fresh medium containing 1% DMSO. Reduction of cell growth by hydroxamates is completely and immediately reversible upon removal. In contrast, the inhibition of DMSO inducibility is not reversible within 24 h. Cell pretreated with hydroxamates for 24 h prior to a 96 h-exposure to DMSO show the same reduction in synthesis of hemoglobin as cells simultaneously exposed to DMSO and hydroxamates.

Alteration of fecal bacterial flora following oral administration of bifidobacterial preparation

The fecal bacterial flora was examined in multiple stool specimens from 14 subjects with gastrointestinal disorders before, during and after the oral administration of bifidobacterial preparation (BBG, viable B. breve and B. bifidum, 3 X 10(9) or 6 X 10(9) per day) for 2 or 3 weeks. Enumerations of fecal bacterial flora showed no conspicuous alterations in total anaerobic bacterial counts during the BBG therapy, however the total number of bifidobacteria in feces increased significantly, and of E. coli and other aerobacteria showed a tendency to decline. The administered B. breve and B. bifidum were recovered in the feces at a concentration of 10(8)/g and of 10(7) to 10(8)/g, respectively. Both species continued to be excreted over 2 weeks after completion of the medication in the feces at concentrations of 10(6) to 10(7)/g and of 10(5) to 10(6)/g respectively, and diminished rapidly in 5 patients and continued at essentially the same level as during the medication in 6 patients. During the treatment the pH, urease activity and ammonia content in feces became lowered and showed a rerise after therapy. Symptomatic discomforts including abdominal distension and pain, anorexia, edema and fever of undetermined origin were reduced during the therapy. Urinalysis, hematological examinations and blood biochemical tests including blood ammonia level, however revealed no significant change.

Urea metabolism in isolated perfused lungs of the laboratory rat and of a desert rodent, Notomys alexis

1. Using the isolated perfused lung preparation we have demonstrated a low-activity ureolytic enzyme present in rodent lung tissue. The enzyme shares four characteristic features with jack bean urease (EC 3.5.1.5). 2. Ureolytic activity was inhibited by fluoride ions and methionine hydroxamic acid; using the latter inhibitor, the I50 value and maximum inhibition were similar to those reported for jack bean urease. The apparent Km for rat lung urease was similar to the plasma urea level. 3. The low level of urease activity in the rat lung and in that of Notomys alexis, a desert rodent, suggests that the enzyme is not involved in urea excretion, rather that pulmonary ammonia production may influence fluid balance at the alveolus.

Regulation of blood ammonia

Disturbance of ammonia metabolism is an important but not the only factor in the genesis of hepatic coma. In this review mechanisms controlling the concentration of ammonia in the blood other than disturbed liver function have been discussed. The key function of ammonia in the pyridine nucleotide cyde has been outlined and it is suggested that the function of this cycle in patients with liver disease would repay further study.