Sensitivity to tumor promotion of SENCAR and C57BL/6J mice correlates with oxidative events and DNA damage

Significant differences in sensitivity to multistage carcinogenesis have been noted between mice that are sensitive (SENCAR) and resistant (C57BL/6J) to 12-O-tetradecanoylphorbol-13-acetate (TPA). However, the mechanism of this sensitivity has not yet been established. Recent studies from this laboratory have shown that TPA significantly enhances formation of hydrogen peroxide (H2O2) and oxidized DNA bases in SENCAR mouse skin, as it increases the infiltration of polymorphonuclear leukocytes (PMNs), as quantitated by myeloperoxidase (MPO). In the studies reported here, we compared SENCAR and C57BL/6J mice with respect to TPA-mediated edema, hyperplasia, PMN infiltration, oxidant formation and oxidative DNA damage in mouse skin. Topical application of two TPA doses (2x2-40 micrograms, 20 h apart) dose-dependently increased PMN infiltration and oxidant formation in both mouse strains, which was consistent with TPA-induced morphological alterations (edema and hyperplasia). However, at low TPA doses (2-4 micrograms), the increases over controls in the SENCAR mice were significantly greater (P < 0.01) than those in C57BL/6J mice. Comparison of the net values indicated that 4 micrograms TPA enhanced PMN infiltration (MPO units/cm2) and oxidant formation (nmol H2O2/cm2) in SENCAR mice by 7.7- and 11-fold respectively over those present in TPA-treated C57BL/6J mouse skin. At the same dose, TPA also significantly increased formation of thymidine glycol (dTG; 5.5-fold), 5-hydroxymethyl-2'-deoxyuridine (HMdU; 4.9-fold) and 8-hydroxyl-2-deoxyguanosine (8-OHdG; 11.4-fold) in SENCAR mouse epidermis. Then, the levels of all three declined. In C57BL/6J mice, there were virtually no increases at 4 micrograms TPA, but their levels gradually increased with higher TPA doses and reached maxima at 10 micrograms TPA for dTG (1.9-fold increase), at 20 micrograms TPA for 8-OHdG (6.0-fold), and at 30 micrograms TPA for HMdU (1.8-fold). We conclude that the TPA-mediated oxidative events and oxidative DNA modification by different doses of TPA correlate with the promoting potencies of those doses in both mouse strains. Therefore, they could be, at least in part, responsible for the strain-dependent sensitivity to tumor promotion.     

The convergent flow of polymeric liquids

Summary An analysis is performed of the changes of the hydrodinamic field which express theirself in a formation of a birefringent inlet stream on flowing of the elastic liquid in an orifice. It is shown that the deformation of pure shear (longitudinal flow) is enfeebled and the deformation of simple shear (the flow with a transverse velocity gradient) is increased. Since for an elastic fluid the dissipation of energy in a longitudinal field is higher than in a transverse field, this conclusion must be considered as a corollary of Heimholtz's theorem on the minimum of dissipation of energy on flow.     

Influence of pulsed arc parameters on powder production in ethanol

Powder consisting nickel and carbon particles were synthesized using a pulsed arc between Ni electrodes submerged in pure ethanol. The ethanol was arc treated for 5 min with 20 and 40 μs duration pulses, at a repetition rate of 100 Hz. The pulse energy was varied in a range of 7.7-192 mJ. Powder samples were obtained by extracting liquid from the treatment vessel after a pre-determined sedimentation time, or by allowing the liquid to evaporate from the vessel, and collecting the residue. The samples were examined by HRSEM, EDX and XRD. Dependencies of the particle structure and size distribution, and the powder production rate and composition, on the pulse energy and duration were studied.The powder samples consisted of nickel and carbon particles. The surface of the nickel particle had a carbon coating. The Ni concentration increased from 32% to 46%, and the C concentration decreased from 68% to 54%, when the pulse energy was increased from 7.7 to 100 mJ with 20 μs pulses. For 40 μs pulses the same changes of Ni and C concentrations were obtained when the pulse energy increased from 60 to 100 mJ. The production rate of the Ni and C particles linearly increased with pulse energy.The particle quantity and size distribution width increased with pulse energy. The maximum particle diameter increased from 70 to 550 nm while its minimum diameter remained ∼ 50 nm when the pulse energy increased from 7.7 to 48 mJ with pulse duration of 20 μs.     

On entire-domain basis functions with square-root edge singularity[EM scattering]

The surface current density generated on thin conducting scatterers or radiations has a well-known singular edge behaviour. Using an explicit transformation between certain regular and singular basis functions, the author compares the convergences of the current expansions of both sets. Also studied are the complementary expansions of the scattered field which result from integrating the current. The discussion is extended to periodic strip structures where the phenomenon of relative convergence is demonstrated     

Characterization of the mRNA encoding a proline-rich 37-kilodalton glycoprotein from the excretory-secretory products of Trichostrongylus colubriformis

A glycoprotein, with apparent molecular weight in SDS-polyacrylamide gels of 37 kDa, has been isolated from the excretory-secretory (ES) products of the adult stage of Trichostrongylus colubriformis, a parasitic nematode. This protein is the major ES product recognized in immunoblots by lymph from a naturally infected sheep. A synthetic oligonucleotide, based on peptide sequence data from a digest of the purified protein was used to successfully screen a cDNA library. A cDNA clone was isolated which encoded a presumptive protein precursor of 220 amino acids that contained a 63 amino acid region of which more than 35% of the residues were proline, three peptide sequences determined from the natural component, and three potential N-glycosylation sites, consistent with the protein being isolated from the lectin-bound fraction of the adult ES products. The presumptive, processed, amino terminus encoded by the cDNA clone was preceded by a signal-like, hydrophobic-rich region of 16 amino acids.     

Performance of four computer-based diagnostic systems

BACKGROUND: Computer-based diagnostic systems are available commercially, but there has been limited evaluation of their performance. We assessed the diagnostic capabilities of four internal medicine diagnostic systems: Dxplain, Iliad, Meditel, and QMR. METHODS: Ten expert clinicians created a set of 105 diagnostically challenging clinical case summaries involving actual patients. Clinical data were entered into each program with the vocabulary provided by the program's developer. Each of the systems produced a ranked list of possible diagnoses for each patient, as did the group of experts. We calculated scores on several performance measures for each computer program. RESULTS: No single computer program scored better than the others on all performance measures. Among all cases and all programs, the proportion of correct diagnoses ranged from 0.52 to 0.71, and the mean proportion of relevant diagnoses ranged from 0.19 to 0.37. On average, less than half the diagnoses on the experts' original list of reasonable diagnoses were suggested by any of the programs. However, each program suggested an average of approximately two additional diagnoses per case that the experts found relevant but had not originally considered. CONCLUSIONS: The results provide a profile of the strengths and limitations of these computer programs. The programs should be used by physicians who can identify and use the relevant information and ignore the irrelevant information that can be produced.     

Maternal viral genotypic zidovudine resistance and infrequent failure of zidovudine therapy to prevent perinatal transmission of human immunodeficiency virus type 1 in pediatric AIDS Clinical Trials Group Protocol 076

Maternal samples were assessed from 96 women enrolled in Pediatric AIDS Clinical Trials Group protocol 076 to determine the prevalence of human immunodeficiency virus type 1 (HIV-1) genotypic zidovudine resistance at entry, if zidovudine resistance developed on study, and the role of zidovudine resistance in vertical transmission of HIV-1 despite zidovudine therapy. Low and high levels of genotypic resistance were assessed by differential hybridization, oligoligation, or direct sequencing of plasma HIV-1 RNA for codons K70R and T215Y/F. None of the women had high-level genotypic resistance to zidovudine at study entry or delivery. For low-level zidovudine resistance, the 95% confidence intervals were 0.3%-6.8% for baseline prevalence and 0.3%-14% for delivery incidence. Low-level zidovudine resistance, adjusted for plasma viral RNA level at delivery, was not strongly associated with an increase in vertical transmission risk (odds ratio, 4.8; 95% confidence interval, 0.2-131; P = .35).     

Sperm motility is a major determinant of pregnancy outcome following intrauterine insemination

The presence and the distribution of neuroendocrine cells in the gastrointestinal tract of adult wild boar were investigated. The endocrine cells have been identified by means of immunocytochemical techniques using antibodies against serotonin, gastrin, somatostatin, cholecystokinin (CCK), met-enkephalin (MET-ENK), gastric-inhibitory peptide (GIP) and glucagon. The number of positive cells for each antiserum in each region was evaluated. Results were compared with data present in the literature and obtained previously by us and other authors in swine and domestic mammals (Ceccarelli et al., 1985, 1987, 1990, 1991, 1995; Capella and Solcia, 1972; Domeneghini and Castaldo, 1981; Peranzi and Lehy, 1984; Krause et al., 1985).