Mapping of polyomavirus DNA replicative intermediates by two-dimensional gel analysis using chemiluminescent detection

Py DNA replicative intermediates (RIs) were mapped using a neutral/neutral two-dimensional (N/N 2D) technique by both chemiluminescent and radioactive detection. The nonradioactive method provides similar sensitivity to radioactive methods while possessing the advantages of stability of labeled probes, faster processing, multiple exposures, easy disposal and safety associated with nonradioactive detection. Application of this method to 2D gel analysis requires some technical modification to reduce background and save the substrate. The patterns of Py RIs with Afl II digestion suggest that bidirectional replication occurs during Py DNA synthesis in cell culture, but other unexpected structures of DNA replication are also seen.

[Influences of early enteral feeding enriched with glutamine on the gut blood flow and oxygen consumption in severely burned mini-swines]

In order to investigate the effects of L-glutamine on the gut blood flow and oxygen consumption after burn, 14 mini-swines were randomly and equally divided into Non-Gln group and Gln group (which was supplied with L-glutamine, 0.64 g/kg day). Gut blood flow and oxygen consumption were continuously determined from preburn to PBD 10. The results showed that portal venous blood flow (Fpv) and oxygen consumption decreased markedly in all animals, especially the Non-Gln group (P < 0.01), on PBD 4 to PBD 10, when Fpv and oxygen consumption returned to preburn level in Gln group and remained low in Non-Gln group. The portal venous MDA concentration was significantly higher in Non-Gln group than that of Gln group. The results suggest that early enteral feeding enriched with glutamine increases the intestinal blood flow, and decreases the intestinal hypoxemia and reperfusion injury.

[Enhancement of gut absorptive function by early enteral feeding enriched with L-glutamine in severe burned miniswines]

14 miniswines (with multiple catheterization and 30% TBSA full thickness burns) were randomly and equally divided into N-Gln group and GLN group. Animals of GLN group were supplied with L-glutamine by 0.64%/kg.d and N-GLN group received equal amount of non-glutamine amino acids. Portal venous blood flow and gut absorptions of glucose, amino acids as well as fat were determined on PBD (post burn day) 1, 4, 7 and 10. The results indicated that the gut absorption obviously decreased in both group on PBD1, but the absorption of glucose and amino acids were much higher in Gln group than that of N-Gln group (P < 0.01). The absorptions of glucose, fat amino acids quickly increased in Gln group from PBD4, and tended to reach the preburn level on PBD7 and PBD10, meanwhile N-Gln group exhibited a slow increase of gut absorption. The absorptions of glucose, fat and amino acids were obviously lower than those of preburn on PBD7 and PBD10 (P < 0.01). This result suggests that oral feeding of glutamine improves efficiently the gut absorptive function after severe burns.

[Chemotherapy against lymphatic metastases of gynecologic cancer via pelvic retroperitoneal cannulation: a preliminary report]

Lymphatic metastasis is one of the most important problems in the treatment of gynecologic malignancy. We conducted a preliminary investigation on the feasibility and practicality of chemotherapy against lymphatic metastases of gynecologic cancer via pelvic retroperitoneal cannulation. 5-FU mixed with Isovist-300 was injected into the pelvic retroperitoneal space. X-ray films revealed that the external iliac, hypogastric, obturator, deep inguinal and most of the common iliac lymph nodes were submerged in the 5-FU solution. 5-FU concentrations in the lymph nodes were measured by high pressure liquid chromatography, which showed that 5-FU concentration of the study group was 2 to 10 times that of the control group. Pathologic findings revealed that most of the metastatic cancer cells in the study group showed obvious degeneration and necrosis while no changes were observed in the control group. No major complications or adverse effects were observed. Our results suggest that this method may be used to treat the lymphatic metastases of gynecologic cancer.

Substituent effects on the genotoxicity of 4-nitrostilbene derivatives

4-Nitrostilbene and twelve of its derivatives (eleven E-stilbenes and two Z-stilbenes) were examined for possible quantitative structure-activity relationships of their in vitro and in vivo genotoxicity. Relative mutagenicity was studied with and without S9 activation in Salmonella strains TA98 and TA100, as well as in the nitroreductase deficient strains TA98/NR and TA100/NR. Chromosomal aberrations in the bone-marrow cells of mice following intraperitoneal administration of the nitrostilbenes were observed as an indicator of in vivo genotoxicity. All of the compounds were active in TA98 and TA100 without S9 activation, with the exception of 4-amino-4'-nitrostilbene in TA100. Mutagenic activity was greatly reduced or eliminated in the NR strains, which is consistent with metabolic activation of the compounds by bacterial reductase. The presence of S9 lowered the activity of most of the nitrostilbenes presumedly by enzymatic detoxication. Hammet values of substituents, partition coefficients and frontier orbital energies (ELUMO and EHOMO) were studied for correlations with mutagenicity of the eleven E-stilbenes. Correlations could be established between mutagenicity in TA98 without S9 activation and the Hammet values. The same mutagenicity could also be correlated to ELUMO. Rationales for these correlations include the concept that electron-withdrawing groups which lower ELUMO should facilitate the reduction of the nitro group, leading to the proximate mutagen hydroxylamine. The correlations are also explained by the concept that electron-withdrawing groups should help stabilize the hydroxylamine intermediate and make the ultimate mutagenic species, the nitrenium ions, more reactive toward DNA. The relationship between mutagenicity and electronic effects of substituent groups found in vitro could not be extended to the in vivo results. However, except for the dinitrostilbenes, where insolubility prevented their testing, all the nitrostilbenes produced a statistically significant increase in chromosomal aberrations compared to the negative solvent control.

Intracellular receptor-type transcription factor, LasR, contains a highly conserved amphipathic region which precedes the putative helix-turn-helix DNA binding motif

We have cloned and sequenced the lasR gene, which is involved in the transcriptional activation of several pathogenic factors, from Pseudomonas aeruginosa IFO3455 and PA103. These clones were predicted to be an open reading frame of 239 amino acids as reported for the PAO1 strain. There is only a single base change resulting in an amino acid exchange from M145 (PAO1) to I (IFO3455). PA103 DNA differs with PAO1 DNA in two bases resulting in only a single amino acid substitution from R179 to W. When the IFO3455 LasR was expressed in a PA103 strain which is known to be LasR defective, proteinase gene activation was detected, however, when PA103 LasR was expressed, no enhancement was measurable. From these results, it appears that the amino acid substitution of R179 to W inactivated LasR activity. This substitution is located in the highly conserved sequence found in many transcription factors, including sigma factors, and may disrupt amphipathic alpha-helix, predicted for the 176 to 189 region, which precedes the putative helix-turn-helix DNA binding motif. We presumed that these three helices may contribute to specific DNA binding.

[Changes in fat absorption and effect of early enteral feeding following burn injury]

In order to approach this problem, a new animal model was developed in this study. Results indicated that the intestinal ability of absorbing nutrients was not markedly attenuated, and the reduction of portal blood flow was the primary cause of decrement of absorption of nutrients after burn injury. Therefore it is proposed that a timely and effective restoration of the portal circulation might improve the absorption ability. From the results of our present study, it seems probable that early enteral feeding can significantly increase the portal blood flow.

Substituent effects on the in vitro and in vivo genotoxicity of 4-aminobiphenyl and 4-aminostilbene derivatives

4-Amino-4'-substituted biphenyls and 4-aminostilbenes substituted in the 3' or 4' position were studied for their in vitro and in vivo genotoxicity. The in vitro mutagenicity of the biphenyls with and without S9 activation was established with Salmonella strains TA98 and TA100 and that of the stilbenes with the same strains plus TA98/1,8-DNP6. The in vivo genotoxicity assay with both series of compounds was for chromosomal aberrations in the bone-marrow cells of mice following intraperitoneal administration of the chemicals. Hammett values of substituents, partition coefficients and frontier orbital energies (ELUMO and EHOMO) of the compounds were used for correlations with mutagenicity. The Salmonella mutagenicity in TA98 and TA98/1,8-DNP6 with S9 was correlated to Hammett sigma + values for the 4-aminostilbene substituents, showing a strong trend of increasing mutagenicity with an increase in the electron-withdrawing capability of the substituent. Hydrophobicity of the stilbenes, however, had little effect on their relative mutagenicity. The 4-aminobiphenyls showed a correlation between their mutagenicity and Hammett sigma + values of their 4'-substituents in stain TA98 with S9, although the trend was not as strong as for the stilbenes. But unlike the stilbenes, TA98 mutagenicity of the biphenyls could also be correlated to hydrophobicity, and structure-activity correlations for the biphenyls was substantially improved when both sigma + and hydrophobicity data were included. For strain TA100 with S9, little correlation was found between mutagenicity of the stilbenes and any of the parameters. However, a limited correlation did exist between the mutagenicity of the biphenyls and their hydrophobicity. There was also limited correlations of the mutagenicity for the stilbenes in TA98 and TA98/1,8-DNP6 with S9 to ELUMO or EHOMO. The in vivo genotoxicity results for the biphenyls and stilbenes could not be correlated to electronic effects as for the in vitro results, nor could they be explained by hydrophobicity. However, it is interesting to note that 3'-substituted 4-aminostilbenes were all substantially more genotoxic in vivo than their corresponding 4'-substituted counterparts. The most genotoxic compound in vivo in either series was 4-aminostilbene which would not have been predicted from the in vitro results.

ortho-Substituent effects on the in vitro and in vivo genotoxicity of benzidine derivatives

Benzidine and its 3,3'-diamino, 3,3'-dimethyl, 3,3'-dimethoxy, 3,3'-difluoro, 3,3'-dichloro, 3,3'-dibromo, 3,3'-dicarbomethoxy and 3,3'-dinitro derivatives together with 2-nitrobenzidine and 3-nitrobenzidine were compared for their in vitro and in vivo genotoxicity. Relative mutagenicity was established with Salmonella strains TA98, TA98/1,8-DNP6 and TA100 with and without S9 activation. All the derivatives in the presence of S9 were more mutagenic than benzidine with 3,3'-dinitro- and 3-nitro-benzidine having the greatest mutagenicity. Mutagenicity in all 3 strains with S9 activation could be correlated to electron-withdrawing ability of substituent groups, as measured by the basicity of the amines. This correlation was explained on the basis that electron-withdrawing groups could favor the stability of the mutagenic intermediate N-hydroxylamine and also enhance the reactivity of the ultimate mutagenic species, the nitrenium ion. Mutagenicity was also correlated to the energy of the lowest unoccupied molecular orbitals (ELUMO). Hydrophobicity was found to have very limited effect on the relative mutagenicity of our benzidine derivatives. The in vivo endpoint was chromosomal aberrations in the bone-marrow cells of mice following intraperitoneal administration of benzidine and its derivatives. In contrast to the in vitro results, while all the amines were genotoxic in vivo, only the 3-nitro derivative had a significant increase in toxicity over benzidine.

Predictions of the Gauss-Hermite beam model and finite element methodf or ultrasonic propagation through anisotropic stainless steel

The predictions of the Gauss-Hermite beam model are compared to those obtained by the finite-element method for a model problem. This is motivated by the desire to examine the trade-offs between computational speed and accuracy in the Gauss-Hermite model. In the model problem, a contact strip transducer radiates through an isotropic layer of ferritic steel into an anisotropic layer of austenitic stainless steel with various directions of the preferred axis of columnar grain alignment. Comparisons are made of time-domain waveforms in a common observation axis in the austenitic material. The predictions of the two models are found to be in good agreement near the center of the beam, with deviations developing as one moves away from the central ray. These are interpreted to be a consequence of the Fresnel approximation made in the Gauss-Hermite model. However, the region that contains most the energy is in the vicinity of the central ray, where there is excellent agreement between the two models. This loss in accuracy is accompanied by a several orders of magnitude increase in computation time.

The genotoxicity of enantiomeric aliphatic epoxides

The (R)- and (S)-optical isomers of 9 epoxides, benzyloxymethyloxirane, epichlorohydrin, glycidol, glycidyl 3-nitrobenzenesulfonate, glycidyl 4-nitrobenzoate, glycidyl tosylate, styrene oxide, glycidyl 1-naphthyl ether and glycidyl 4-nitrophenyl ether, have been compared for their in vivo and in vitro genotoxicity. The in vitro short-term test employed was the Ames mutagenicity assay with Salmonella strain TA100. The in vivo tests were chromosomal aberrations (CA) as well as sister-chromatid exchange (SCE) in bone-marrow cells of mice following intraperitoneal administration of these epoxides. Differences in mutagenicity between isomers were established with TA100 for all the compounds. While 13 of the isomers were genotoxic compared to a negative control by CA measurements, only in the case of glycidyl 4-nitrobenzoate could a significant difference be found between isomers by this test. However, with SCE evaluations, differences were detected between the (R)- and (S)-isomers for all the pairs of compounds with the exception of those for benzyloxymethyloxirane and glycidyl 4-nitrophenyl ether. At least in part, differences in the patterns of genotoxicity among compounds can be related to their differences in reaction pathways.

Enantioselective detoxication of optical isomers of glycidyl ethers

The detoxication of the enantiomers of glycidyl 4-nitrophenyl ether (GNPE), (-)-(R)- and (+)-(S)-GNPE, and glycidyl 1-naphthyl ether (GNE), (-)-(R)- and (+)-(S)-GNE, by rat liver glutathione transferase and epoxide hydrolase was studied. Enantioselectivity was observed with both enzymes favoring the (R)-isomers as determined by the formation of conjugate, diol, and remaining substrate measured by HPLC. Enantiomers of GNE were detoxified by cytosolic epoxide hydrolase but those of GNPE were not. Substantial nonenzymatically formed conjugates of enantiomers of GNPE were detected showing (S)-GNPE the more reactive of the pair.

Numerical simulation of ultrasonic wave propagation in anisotropic and attenuative solid materials

The axisymmetric elastodynamic finite element code developed is capable of predicting quantitatively accurate displacement fields for elastic wave propagation in isotropic and transversely isotropic materials. The numerical algorithm incorporates viscous damping by adding a time-dependent tensor to Hooke's law. Amplitude comparisons are made between the geometric attenuation in the far field and the corresponding finite element predictions to investigate the quality and validity of the code. Through-transmission experimental measurements made with a 1 MHz L-wave transducer attached to an aluminum sample support the code predictions. The algorithm successfully models geometric beam spreading dispersion and energy absorption due to viscous damping. This numerical model is a viable tool for the study of elastic wave propagation in nondestructive testing applications.