Enterococcus faecalis V583 contains a cytochrome bd-type respiratory oxidase.

We have cloned an Enterococcus faecalis gene cluster, cydABCD, which when expressed in Bacillus subtilis results in a functional cytochrome bd terminal oxidase. Our results indicate that E. faecalis V583 cells have the capacity of aerobic respiration when grown in the presence of heme.

Studies on the mechanism of urotoxic effects of N,N'-dimethylaminopropionitrile in rats and mice. 1. Biochemical and morphologic characterization of the injury and its relationship to metabolism.

N,N'-Dimethylaminopropionitrile (DMAPN), a major component of the NIAX catalyst ESN, is known to cause urinary bladder dysfunction in exposed workers. In order to investigate the mechanism of DMAPN toxicity, we carried out time-course (0-72 h) and dose-response (175-700 mg/kg) studies on the effects of DMAPN in rats and mice. Treated animals exhibited several signs of toxicity including loss of body weight, reduced water consumption, and bladder urine retention, as well as bladder injury. DMAPN-induced bladder injury was characterized by distended bladders with marked diffuse submucosal and subserosal edema, petechial hemorrhage, and multifocal perivascular inflammatory infiltrates. The qualitative and quantitative analysis of urine indicated hypoosmolality, aciduria, hematuria, proteinuria, and oliguria. Elevated levels of creatinine and urea levels in plasma were indicative of renal dysfunction. Within hours following DMAPN administration, the animals exhibited a significant increase in urinary retention that resolved between 60 and 72 h. Rats excreted about 44% of the administered DMAPN dose unchanged in the urine, while mice excreted only about 6% of the dose. Commercially available DMAPN metabolites, administered by gavage, produced toxic effects less adverse than DMAPN. The biochemical effects of DMAPN included depletion of glutathione and increased lipid peroxidation in target organs, including urinary bladder and kidney. These studies indicate that there are species differences in DMAPN toxicity. The differences may be due to differences in the formation of reactive metabolic intermediates of DMAPN.

Comparative double-tracer whole-body autoradiography: uptake of 11C-, 18F- and 3H-labeled compounds in rat tumors.

The uptake of various labeled compounds by tumors was studied by double-tracer whole-body autoradiography (DTWBA) in rats. Each animal carried two types of tumors: mammary carcinomas and the Walker 256 carcinosarcomas. The markers used were [18F]- and [3H]fluorodeoxyglucose (glucose utilization), [3H]thymidine (cell proliferation), [11C]methionine (amino acid metabolism) and [11C]- and [3H]toremifene (estrogen-receptor-avid agents). In each experiment, the distribution of a substance labeled with short-lived radionuclide (11C or 18F) was compared with that of another substance labeled with a long-lived nuclide (3H). Quantification was done by combining computerized image analysis of the autoradiograms with liquid scintillation counting of punched tissue pieces obtained from the cryosections. The relationships between the uptakes of the various radiopharmaceuticals were recorded in tumors and normal tissues. The dynamics of [18F]fluorodeoxyglucose and [11C]methionine were determined in tumors and some selected tissues by positron emission tomography (PET). The uptake rate between fluorodeoxyglucose and thymidine in the mammary tumor was five times higher than the ratio in the Walker tumor. The corresponding figure for FDG/methionine was four times. Thymidine, compared with methionine, was twice as efficient. Thus, the mammary tumors were best imaged with FDG or thymidine. The non-steroid antiestrogen toremifene was taken up in very low amounts by these tumors. By DTWBA, experimental tumors may serve as their own control.

Cardiac puncture in the mouse through the anterior thoracic aperture.

The puncture is performed during ether anaesthesia and will usually give 0.6-0.8 ml within 10-15 s. Blood volumes up to 1 ml have frequently been obtained from adult mice with this method.

Effect of cyanide antidotes on the metabolic conversion of cyanide to thiocyanate.

The excretion of thiocyanate following the administration of equitoxic doses of cyanide to unprotected mice and to animals pretreated with various cyanide antidotes has been studied. The results demonstrate that cyanide given alone or to animals pretreated with thiosulfate is extensively converted to thiocyanate. Animals pretreated with sodium nitrite or a combination of nitrite and sodium thiosulfate excreted even higher amounts of thiocyanate. This demonstrates that cyanide originally detoxified by combination with methemoglobin is ultimately converted to thiocyanate in the animal body. Pretreatment of animals with cobalt compounds (cobaltous chloride or dicobalt-EDTA) or a combination of cobalt compounds and thiosulfate resulted, on the other hand, in a less efficient conversion of cyanide to thiocyanate. The cyanide detoxified by trapping as highly undissociated cobalt-cyanide complexes is instead excreted in the urine, as demonstrated by detection of high amounts of cobalt ions and strongly complex-bound cyanide in the urine from animals treated with cobalt compounds and cyanide. A method for the determination of cyanide present as cobalt-cyanide complexes is described and its forensic application is proposed.