Potentiation of dimethylnitrosamine genotoxicity in rat hepatocytes isolated following ethanol treatment in vivo

Unscheduled DNA synthesis (UDS), following exposure to dimethylnitrosamine (DMN), was potentiated in cultured hepatocytes isolated following treatment of rats for 14 or 28 days with 20% ethanol/5% sucrose solution. Ethanol treatment was associated with increased UDS, a concomitant increase in hepatic microsomal protein concentration and DMN N-demethylase activity. Increased aniline hydroxylase activity of hepatic microsomes from ethanol-treated rats preceded the measured increase in microsomal protein content or DMN metabolism. The increase in metabolism of DMN in vitro and potentiation of DMN-induced UDS associated with ethanol treatment may contribute to a synergistic effect of ethanol on DMN hepatotoxicity and carcinogenicity. In contrast, ethanol pretreatment did not increase the cytotoxicity of DMN as characterized by enzyme release.     

Plant biomass and nutrient levels of a tropical macrophyte (Cyperus papyrus L.) receiving domestic wastewater

The aboveground biomass and nutrient content ofCyperus papyrus were determined in a small tropical swamp receiving domestic wastewater. It was found that the biomass (4,955 g.m^–2 dry weight) was the highest ever reported for papyrus. The levels of both nitrogen and phosphorus in the plant organs were very high. The nitrogen concentrations of the various plant organs were 4.8% roots, 8.4% rhizomes, 4.5% scales, 4.8% culms, and 6.2% umbels on dry weight basis. As to phosphorus the concentrations were 0.09% roots, 0.11% rhizomes, 0.09% scales, 0.10% culms, and 0.13% umbels. The high biomass and nutrient contents of the plants may have been caused by the high nutrient levels in the surrounding water. Comparison of the nitrogen to phosphorus ratios in the plants to those in the surrounding water showed that the plants stored very high amounts of nitrogen.     

A possible phagocytic role for folliculo-stellate cells of anterior pituitary following estrogen withdrawal from primed male rats

Summary Ultrastructural changes suggesting a phagocytic role for the nongranular folliculo-stellate cells of the anterior pituitary are investigated in estrogen-primed male rats after withdrawal of estrogen. Morphological changes in mammotropes following the removal of a subcutaneous estradiol-containing Silastic implant include the formation of intracellular lipid bodies. These lipid bodies appear to be associated with enhanced estrogen-dependent prolactin secretion in mammotropes. Seven and 24 h after estrogen withdrawal intracellular lipid within mammotropes seems to be released into the intercellular space. Seventy-two h after estrogen withdrawal, lipid droplets are almost entirely cleared from mammotropes while folliculo-stellate cells become packed with lipid globules. Folliculo-stellate cells also undergo dramatic hypertrophy 7 and 24 h after the removal of E2-containing implants. Extensive intercellular junctions including zonulae adhaerentes, desmosomes, and putative gap junctions are formed. Intercellular junctions delineate extravascular channels into which numerous microvilli project. Folliculo-stellate cells appear capable of accumulating many lipid droplets, presumably related to mammotrope metabolism. What appear to be large secondary lysosomes as well as the lipid droplets are observed within folliculostellate cells; lipid, therefore, may be degraded through a lysosomal pathway in folliculo-stellate cells.     

Synthesis of RNA by Rhodomicrobium vannielii swarmer cells

Abstract Protein synthesis in Rhodomicrobium vannielii swarmer cells, incubated anaerobically in the dark, is dependent upon a rifampicin-sensitive step, indicating a dependence upon de novo RNA synthesis. In addition, toluene treatment has shown that the motile, non-differentiating swarmer cells have the capacity to initiate and sustain RNA synthesis. The major form of the DNA-dependent RNA polymerase responsible for this RNA synthesis has been identified.     

Number of somatic and germ cells during early stages of gonadal development in frog larvae treated with zinc sulphate

Summary ZnSO₄ treatment of early frog tadpoles resulted, initially, in a mitotic stimulation of primordial germ cells. In later larval stages, ZnSO₄ was responsible for the atresy of gonads in which germ cell and medullary cell numbers sharply decreased. At the same time, very few germ cells entered the meiotic prophase, while the degeneration of some of them was observed. Our results are discussed in connection with previous findings about the influence of Zn on cellular proliferation.     

Statistical treatment of VAM infection data

Summary The amount of vesicular-arbuscular mycorrhizal (VAM) infection, when expressed as length of infected roots, is commonly quite variable among replicate pots within an experimental treatment. In this paper we show that frequency distributions of VAM infection parameters are often non-normal in form and may follow the negative binomial, a distribution commonly associated with aggregated organisms in nature. The lack of normality means that statistical procedures should either be non-parametric or should include data transformations.     

The action of lipase on chloroplast membranes: II. Polypeptide patterns of bean galactolipase- and phospholipase A2-treated thylakoid membranes

Thylakoid membranes obtained from bean chloroplasts treated with bean galactolipase or phospholipase A₂ (from Crotalus terr. terr.) showed marked changes in their polypeptide patterns when separated on SDS-PAGE. The obtained results have been discussed with regard to the relationship between chloroplast lipids and polypeptides originating from chlorophyll-protein complexes of bean thylakoids. A coexistence between galactolipids and the peripheral antennae in PS I complex and LHCP³ as well as a conspicuous role of phospholipids in PSI and PSII centre chlorophyll-protein complexes has to be underlined.Abbreviations CP1 chlorophyll a-protein complex of PSI - CPa chlorophyll a-protein complex of PSII - D₁₀ digitonin subchloroplast particles enriched in PSII - D₁₄₄ digitonin subchloroplast particles enriched in PSI - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - LHCP^1–3 light harvesting chlorophyll a/b protein complexes - PAGE polyacrylamide gel electrophoresis - PSI photosystem I - PSII photosystem II - SDS sodium dodecyl sulphate - TCA trichloroacetic acid - Tricine N-Tris-(hydroxymethyl)-methylglycine - Tris Tris-(hydroxymethyl)-aminomethan     

The use and utility of EMG biofeedback with chronic schizophrenic patients

This study examined the efficacy of muscle relaxation training via electromyographic (EMG) biofeedback from the frontalis and forearm extensor muscles of schizophrenic inpatients. Thirty chronically hospitalized patients were randomly assigned to one of three conditions: EMG biofeedback from the forearm extensor and frontalis muscles, progressive relaxation, and a control group. Treatment consisted of one session of orientation and baseline, and six sessions of training. The results indicated that the schizophrenic patients receiving EMG training had significantly lower EMG recordings than the progressive relaxation group, which, in turn, was significantly lower than the control group. Analyses of covariance on the Tension-Anxiety scale from the Profile of Mood States revealed no significant effects, while finger-tapping rates were significantly improved only for the arm receiving feedback training in the EMG group. On the Nurses Observation Scale for Inpatient Evaluation the biofeedback group significantly improved on the Social Competence and Social Interest factors.We would like to express our appreciation for the contributions the following people made to this project: Drs. Barry Smith, Robert Steele, Agnes Hartfield, Jeffrey Barth, Althea Wagman, and the late Harold Weiner; Earl Downs and the participating staff at Springfield State Hospital Center; and Robert Kline and Michael Kelley, who performed the data analyses. This research was supported in part by a grant from the Computer Science Center at the University of Maryland.     

Response of pondcypress growth rates to sewage effluent application

Cores were collected from dominant pondcypress trees growing in a swamp that had received sewage effluent for 7 yr and a nearby control swamp to determine the combined effects of changes in nutrient supply and hydrologic regime on tree growth. The cores were used to measure two indices of tree growth: basal area increment (BAI) and relative basal area increment (RBAI, which accounts for differences in growth due to the size of teh tree) between 1970–1983 while one swamp remained untreated and the other received weekly additions of sewage effluent from 1974–1981. Throughout the whole period, the mean BAI and RBAI of pond-cypress trees in the untreated swamp remained unchanged, ranging between 5.55–6.38 cm² yr^–1 and 1.09–1.27% yr^–1, respectively. In contrast, trees in the treated swamp increased their BAI approximately two-fold from 7.40 cm² yr^–1 prior to treatment to 14.83 cm² yr^–1 after the onset of treatment and maintained this rate of growth in the 2 yr period after cessation of treatment. Relative basal area increment showed a similar response, but the proportional increase due to treatment was less (1.5-fold factor) than for BAI. The response of pondcypress trees to the sewage effluent differed depending upon whether the trees were located in the deep or shallow water zones. Trees in the deep zone of the treated swamp had lower BAIs and RBAIs than those in the shallow zone during the treatment period, whereas in pre- and post-treatment periods growth indices were equal in both zones. No significant differences in growth between deep and shallow zones were observed during all three time periods in the control swamp.     

Decrease in the Function of the γ-Aminobutyric Acid-Coupled Chloride Channel Produced by the Repeated Administration of Pentylenetetrazol to Rats

The acute administration of pentylenetetrazol (PTZ; 25-75 mg/kg i.p.) failed to modify the specific binding of t-[35S]butylbicyclophosphorothionate ([35S]TBPS) to membrane preparations from the cerebral cortex of the rat. In contrast, the repeated administration of PTZ (30 mg/kg i.p., three times a week for 12 weeks) reduced by 26% the density of [35S]TBPS binding sites without modifying the dissociation constant. This effect was observed 3 days after the last PTZ administration. A parallel reduction of gamma-aminobutyric acid (GABA)-stimulated 36Cl- uptake was measured in the cerebral cortex of PTZ-treated rats 3 days after the last injection. The repeated administration of PTZ produced sensitization to the drug, or chemical kindling. In fact, no convulsions were observed in the first week of treatment, but all the animals became sensitized to PTZ by the 12th week. The results are consistent with the hypothesis that chronic treatment with PTZ at a subconvulsant dose causes a decrease in GABA-coupled chloride channel activity that may be related to the chemical kindling produced by this compound.