Changes in natural killer cell activity and prostaglandin E2 levels during the progression of diethylnitrosamine-induced hepatocarcinogenesis in Fischer 344 rats

The sequential changes of natural killer cell (NK) activity and prostaglandin E2 (PGE2) during hepatocarcinogenesis induced by diethylnitrosamine (DEN) in male Fischer 344 rats were investigated. DEN at a concentration of 40 ppm was administered in drinking water for 10 weeks. At weeks 5, 10, 20 and 30, rats were autopsied and the development of glutathione S-transferase placental form positive foci (GST-P+ foci) at weeks 5 and 10 and hepatocellular tumors at weeks 20 and 30 were examined. The labeling index of bromodeoxyuridine (BrdU) an indicator of DNA synthesis, was also sequentially checked. GST-P+ foci were found to increase with age. Hepatocellular nodules increased until week 20, but by week 30 when the incidence of hepatocellular carcinoma was 100%, the incidence of nodules had decreased. BrdU positive cells also increased with age, and by week 30 when the incidence of hepatocellular carcinoma was 100%, the number of BrdU-positive cells had decreased. NK cell activity increased until week 10, but at week 20, was less than in the untreated control group. The level of PGE2 increased until week 5, but at week 10, levels were not significantly different from those seen in the untreated control group. On the basis of these results, we concluded that NK activity is closely related to the progression of hepatocarcinogenesis, but PGE2 levels show no significant change.     

Cell surface localization and processing of the ComG proteins, required for DNA binding during transformation of Bacillus subtilis

The comG operon of Bacillus subtilis encodes seven proteins essential for the binding of transforming DNA to the competent cell surface. We have explored the processing of the ComG proteins and the cellular localization of six of them. All of the proteins were found to be membrane associated. The four proteins with N-terminal sequence motifs typical of type 4 pre-pilins (ComGC, GD, GE and GG) are processed by a pathway that requires the product of comC, also an essential competence gene. The unprocessed forms of ComGC and GD behave like integral membrane proteins. Pre-ComGG differs from pre-ComGC and pre-ComGD, in that it is accessible to proteolysis only from the cytoplasmic face of the membrane and at least a portion of it behaves like a peripheral membrane protein. The mature forms of these proteins are translocated to the outer face of the membrane and are liberated when peptidoglycan is hydrolysed by lysozyme or mutanolysin. ComGG exists in part as a disulphide-cross-linked homodimer in vivo. ComGC was found to possess an intramolecular disulphide bond. The previously identified homodimer form of this protein is not stabilized by disulphide bond formation. ComGF behaves as an integral membrane protein, while ComGA, a putative ATPase, is located on the inner face of the membrane as a peripheral membrane protein. Possible roles of the ComG proteins in DNA binding to the competent cell surface are discussed in the light of these and other results.     

MUC6 expression in breast tissues and cultured cells: abnormal expression in tumors and regulation by steroid hormones

DIG-labelled sense and antisense cRNA probes were synthesized from cDNA clones of CymMV and ORSV for virus detection in infected plants. A slot-blot hybridization assay was developed using either crude leaf extracts or total RNA from infected leaves. The assay could detect 50 and 250 pg of purified CymMV and ORSV RNA, respectively. As little as 30 mg of Nicotiana benthamiana infected leaves was sufficient to provide positive detection. CymMV and ORSV were detected at 3125 and 625 times dilution of leaf extracts, respectively. The DIG-labelled cRNA probes are stable for more than a year. This method is sensitive, reliable and suitable for large-scale routine testing of plant viruses. By using the two DIG-labelled cRNA probes in situ, CymMV and ORSV were localized in systemically infected leaves and stems of N. benthamiana and orchids.     

Cellular glutathione peroxidase is the mediator of body selenium to protect against paraquat lethality in transgenic mice

A case-control study was conducted between 1992 and 1996 in six Italian areas. It included 537 women with colon cancer, 291 women with rectal cancer and 2081 control women in hospital for acute conditions, unrelated to hormonal or gynaecological diseases. A higher age at menopause was associated with increased colon cancer risk (odds ratio (OR) for > or = 53 years compared with < 50 years = 1.39, 95% confidence interval (CI) 1.04-1.87). Among parous women, a significant trend of decreasing colon cancer risk with increasing number of births was seen for colon (OR for > or = 4 births compared with 1 birth = 0.62, 95% CI 0.42-0.90), but not for rectal cancer. Nulliparous women, however, were at lower risk than women with a single birth, and age at first birth was directly associated with risk. While oral contraceptive use showed no significant influence, ever users of hormone replacement therapy had a reduced risk of rectal cancer (OR = 0.56, 95% CI 0.31-1.01). Thus, the association of colorectal cancer with reproductive and menstrual factors is neither strong nor consistent.     

Physiological transport properties of cultured retinal microvascular endothelial cell monolayers

PURPOSE: To characterize baseline transport properties: hydraulic conductivity (Lp), albumin permeability (Pe), and transendothelial electrical resistance (TER) of bovine retinal microvascular endothelial cells (RMEC) in the development of an in vitro model of the blood-retinal barrier (BRB). METHODS: RMEC were grown on porous, polycarbonate filters for determination of the number of days required to achieve minimal transport rates. Lp, Pe, and TER were measured by utilizing a bubble tracking spectrophotometer, by quantifying the diffusional movement of fluorescein isothiocyanate-labeled albumin, and by utilizing a Millipore electrical resistance meter, respectively. RESULTS: Lp decreased significantly from 7.82 +/- 0.85 x 10(-7) (mean +/- SEM) cm/sec/cm H2O at post-plating Day 5 to 1.44 +/- 0.26 x 10(-7) cm/sec/cm H2O at Day 9. Pe of the monolayer also decreased progressively with days post-plating from 3.44 +/- 0.53 x 10(-6) cm/sec at Day 7 to a minimum of 1.95 +/- 0.29 x 10(-6) cm/sec at Day II. Peak TER fluctuated until Day 7, when it began to steadily increase from 17.14 ohm-cm2 to a peak value of 25.42 ohm-cm2 at Day 10, decreasing from then on to 22.24 ohm.cm2 on Day 12. Known disrupters of the BRB, NECA and VEGF, elicited significant increase in RMEC Lp showing the sensitivity of this model to pharmacological alterations. CONCLUSIONS: Our data indicate that RMEC grown on polycarbonate filters form a restrictive monolayer of cells, which exhibit dynamic alterations in response to pharmacological agents, thus demonstrating an in vitro model of the BRB. Future studies with the model may offer insights into the pathogenesis of retinal vascular diseases and allow convenient testing of pharmacological interventions.     

Structure-based design of inhibitors of purine nucleoside phosphorylase. 3. 9-Arylmethyl derivatives of 9-deazaguanine substituted on the methylene group

X-ray crystallography and computer-assisted molecular modeling (CAMM) studies aided in the design of a potent series of mammalian purine nucleoside phosphorylase (PNP) inhibitors. Enhanced potency was achieved by designing substituted 9-(arylmethyl)-9-deazaguanine analogs that interact favorably with all three of the binding subsites of the PNP active site, namely the purine binding site, the hydrophobic pocket, and the phosphate binding site. The most potent PNP inhibitor prepared during our investigation, (S)-9-[1-(3-chlorophenyl)-2-carboxyethyl]-9-deazaguanine (18b), was shown to have an IC50 of 6 nM, whereas the corresponding (R)-isomer was 30-fold less potent.     

Electroconvulsive shock does not induce c-fos and junB, but TIS1 and TIS8/zif-268, in neonatal rat hippocampus

Insular neurons responsive to baroreceptor challenge have been identified in the rat, but not previously in primates. Characterization of baroreceptor-related neurons was performed in 15 anesthetized monkeys (Macaca fascicularis) using extracellular single-unit recording techniques. 131 units were investigated within the insula and surrounding regions. Based on their responses to phenylephrine hydrochloride (PE) and sodium nitroprusside (SNP), three types of units were distinguished: 35/131 (27%) sympathoexcitatory (SE), 12/131 (9%) sympathoinhibitory (SI) and 84 (64%) null units. More baroreceptive units were found within the insula (38/73, 52%) than in surrounding areas (9/58, 16%) (p < 0.001). Lateralization was indicated with more baroreceptive units being encountered within the right insula (28/44, 64%) than the left (10/29, 34%) (p = 0.02). The majority of the responsive units were located within the dysgranular and granular insula in layers II, III and V/VI. These data suggest that cardiovascular representation may occur in the primate insula as has been shown in other species.