Nitrite biotransformation by mitochondria from the earthworm Eisenia foetida (Savigny).

1. Nitrite oxidase and cytochrome-c oxidase activity catalysed by cytochrome-aa3 were assayed in earthworms and rats. 2. Cytochrome-aa3 and intact mitochondria from the two species were anaerobically incubated in the presence of nitrite; the occurrence of mitochondria-induced nitrite biotransformations was evaluated by monitoring nitrite recovery in incubation medium. Possible nitric oxide production was also tested. 3. The ratio nitrite oxidase/cytochrome-c oxidase activity was much higher in earthworms than in rats. 4. Under anaerobic conditions and in the presence of respiratory substrates, earthworm mitochondria produced a time-dependent loss of nitrite in the incubation medium. On the contrary, rat mitochondria are unable to decrease environmental nitrite concentration. 5. Results support the notion that metabolic properties of earthworm mitochondria can be considered as an adaptation to chronic nitrite exposure, this toxicant being typically present in natural habitats of these worms.

Flow cytometric DNA index in the prognosis of colorectal cancer.

The authors investigated the relationship between flow cytometric DNA index (DI, defined as the ratio of the DNA content of malignant cells to that of normal cells) and other prognostic factors (grade and stage, anatomical site, age and sex) with the survival of 115 patients with colorectal cancer. Multiple biopsy specimens from 62 patients were taken during colonoscopy before surgery. Additional samples from 53 patients were obtained from paraffin-embedded material. All patients were treated with surgery only. Fresh-frozen material gave higher incidence of DNA aneuploidy than paraffin-embedded material (79% versus 41%). The patients with DNA diploid tumors (DI = 1) had a better overall survival than those with DNA aneuploid tumors (DI = 1). Among DNA aneuploid tumors, those with DI greater than 1.2 (excluding DI = 2) were worse than those with DI = 1.2 (excluding DI = 1) and DI = 2. Cox's regression analysis showed that pathologic stage was more important for prognosis than DNA index, whereas age, sex, histologic grade, and anatomic site were removed from the analysis as not relevant for prognosis. Relative risk of death (RR), in reference to patients with DI = 1 and Stages A + B (RR = 1), were RR = 1.8 for patients with carcinomas with Stage C. RR = 2.7 for patients with carcinomas with DNA near-diploid and DNA tetraploid tumors. RR = 3.5 for those with DI greater than 1.2 (excluding DI = 2), and RR = 8.0 for those with Stage D. These data indicate that flow cytometrically evaluated DI values have a relevant independent power for predicting the clinical outcome of colorectal cancer patients.

Measurement of c-myc protein content and cell cycle kinetics of normal and spontaneously transformed murine mastocytes by bivariate flow cytometry.

Progressive in vitro culturing of interleukin-3 (IL-3) dependent normal murine mastocytes (PB-3) resulted in a variant cell line (PB-1) able to grow without exogenous IL-3 and which was tumorogenic in syngenic mice. Bivariate flow cytometry was used to evaluate the c-myc protein and DNA content of PB-3 and PB-1 cells. The c-myc protein was detected by specific monoclonal antibodies. Kinetic characteristics of PB-3 and PB-1 cell lines, namely, the duration of the G1, S and G2 + M cell cycle phases were also evaluated using the bromodeoxyuridine (BrdU) pulse-chase method and BrdU/DNA flow cytometry. Levels of c-myc protein in PB-1 cells were about two-fold higher than those of PB-3 cells in all cell cycle phases. Mean duration of the cell cycle (Tc) was 15.3 h for PB-3 cells and 12.4 h for PB-1 cells. Shortening in Tc for the transformed cells was due to a decrease of nearly 30% in mean duration of the G1 phase (from 8 h to 5.7 h). No significant differences were found in the duration of the S and G2 + M phases. These results indicate that acquired IL-3 independency in vitro and tumorogenicity of PB-1 cells were accompanied by a doubling of c-myc protein level and by a parallel shortening, or bypass, of the regulatory events within the G1 phase of the cell cycle.

Neurite outgrowth and cell cycle kinetic changes induced by cis-diamminedichloroplatinum II and retinoic acid in a human neuroblastoma cell line.

The aim of this study was to analyze by flow cytometry the effect of cis-diamminedichloroplatinum II (CDDP) and retinoic acid (RA) on the cell cycle of a neuroblastoma cell line (SK-N-BE (2)C NB) and to correlate the kinetic data with cell morphology. CDDP at 1 microgram/ml induced a dramatic G2 + M cell cycle phases block (nearly 200% increase with respect to control) 2 days after treatment. The G2 + M block was spontaneously reversed starting from the 4th day. The cells treated with 10 microM RA were, instead, induced to irreversibly enter the G0 + G1 phase of the cell cycle (nearly 20% increase with respect to control) 48 h after treatment. Neurite-like structures were observed for both CDDP and RA treated cells. These data suggest different cell cycle dependent molecular mechanisms and different degrees of differentiation during CDDP or RA treatment of NB cells.