A comparison of 24 chemicals in the six-well bacterial reverse mutation assay to the standard 100-mm Petri plate bacterial reverse mutation assay in two laboratories.

The bacterial reverse mutation assay (Ames) is a fundamental genetic toxicology test, and efforts to miniaturize the regulatory GLP version are essential in assessing genotoxic liabilities earlier in the drug development pipeline. Two versions of the Ames were compared: the six-well (miniaturized) plate and the standard 100-mm plate test at two different laboratories. Of twenty-four chemicals tested, a subset of six chemicals was tested in the six-well test only and the remaining eighteen were evaluated in both versions of the test. The plate incorporation procedure was used with one Escherichia coli and four different Salmonella strains. The six-well test uses the same plating procedure and evaluation methods as the standard Ames assay in 100-mm plates, but the smaller format requires 20% of the test chemical. Additionally, the six-well test uses a limit concentration of 1000 µg/well versus the standard Petri plate test limit concentration of 5000 µg/plate. Testing across the two formats resulted in 100% concordance in overall mutagenicity judgement and 94% concordance across all tester strains and conditions. Known mutagenic positive control chemicals were correctly detected as positive in both formats. The overall conclusion is that the six-well assay results are concordant with the standard assay format in this evaluation and could be a reliable alternative.

Colectomy without mechanical bowel preparation in the private practice setting.

BACKGROUND: Despite randomized trials and meta-analyses demonstrating the safety of omitting mechanical bowel preparation (MBP) before colorectal surgery, private practice surgeons may hesitate to eliminate MBP for fear of being outside community standards. This study evaluated the safety of eliminating MBP before colectomy in a private practice setting. METHODS: This prospective observational study included elective abdominal colorectal operations from one surgeon's practice from October 2008 to June 2011. MBP was not routinely utilized after November 2009. Postoperative 30-day complication rates and length of hospital stay were compared in patients with and without MBP. Multivariable regression models were developed to compare outcomes among study groups, adjusting for demographics, diagnoses, procedures, and year. RESULTS: A total of 165 patients were analyzed. Demographics were similar between groups. Laparoscopic procedures were more common in patients without MBP due to increased laparoscopy over time (43 vs. 61 %, p = 0.03). As regards complications, infection rates were similar between groups (MBP 10.5 % vs. no MBP(NMBP) 11.4 %, adj p = 0.57). Patients without MBP had a shorter length of hospital stay (median: 6 vs. 5 days, p = 0.01), but those differences were not statistically significant after adjustment (p = 0.14). CONCLUSIONS: Private practice surgeons should embrace evidence-based practice changes and make efforts to quantitatively evaluate the safety of those changes. Omission of MBP for most elective colectomy procedures appears to be safe with no significant increase in complications or length of hospital stay. Because MBP has substantial drawbacks, there is little justification for its routine use in the majority of elective abdominal colorectal procedures.

Effect of feed type and sex on digestibility and feed efficiency utilization in black spiny-tailed iguana (Ctenosaura pectinata).

Digestibility, feed efficiency, and the effect of sex were evaluated in black iguanas (Ctenosaura pectinata) using two commercial pellets (rabbit and chicken). The experiment was performed in 80 iguanas in a completely randomized design with a factorial arrangement 2×2 over 105 days. No differences were detected by food type in weight gain (chicken vs. rabbit: 121 vs. 154 mg/d) and daily intake (chicken vs. rabbit: 524 vs. 551 mg/d), but differences were detected (P<0.05) in feed conversion (chicken vs. rabbit: 6.45 vs. 4.47). Rabbit pellets showed higher digestibility than chicken food (P<0.01) in dry matter (59.8 vs. 41.4%) and NDF (55.4 vs. 43.6%), respectively. Sex had no effect in any of the variable responses. Black iguanas can be raised since 6 months old in captivity with commercial food designed for rabbit or broiler. No special physiological adaptations occur in black iguanas correlated with change in feeding habits during ontogeny.

Genome sequence of the radioresistant bacterium Deinococcus radiodurans R1.

The complete genome sequence of the radiation-resistant bacterium Deinococcus radiodurans R1 is composed of two chromosomes (2,648,638 and 412,348 base pairs), a megaplasmid (177,466 base pairs), and a small plasmid (45,704 base pairs), yielding a total genome of 3,284, 156 base pairs. Multiple components distributed on the chromosomes and megaplasmid that contribute to the ability of D. radiodurans to survive under conditions of starvation, oxidative stress, and high amounts of DNA damage were identified. Deinococcus radiodurans represents an organism in which all systems for DNA repair, DNA damage export, desiccation and starvation recovery, and genetic redundancy are present in one cell.

E2F4 regulates a stable G2 arrest response to genotoxic stress in prostate carcinoma.

The retinoblastoma (pRB) family proteins regulate the E2F transcription factors; their complexes regulate critical transitions through the cell cycle. The function of these pRB family/E2F complexes, which includes p130/E2F4, in response to genotoxic agents, is not well understood. We investigated the role of E2F4 in the genotoxic stress response. Following radiation treatment, E2F4 colocalized with p130 in the nucleus during a radiation-induced stable G(2)-phase arrest. Arrested cells had significantly decreased expression of Cyclins A2 and B1 and decreased phosphorylation of mitotic protein monoclonal-2 (MPM-2) mitotic proteins. Small interference RNA (siRNA)-mediated knockdown of E2F4 sensitized cells to subsequent irradiation, resulting in enhanced cellular DNA damage and cell death, as determined by caspase activation and decreased clonogenic cell survival. Downstream E2F4 targets potentially involved in the progression from G(2) into M phase were identified by oligonucleotide microarray expression profiling. Chromatin immunoprecipitation localized E2F4 at promoter regions of the Bub3 and Pttg1 mitotic genes following irradiation, which were among the downregulated genes identified by the microarray. These data suggest that in response to radiation, E2F4 becomes active in the nucleus, enforces a stable G(2) arrest by target gene repression, and thus provides increased cell survival ability by minimizing propagation of cells that have irreparable DNA damage.

Three new species of philometrids (Nematoda: Philometridae) from centrarchid fishes in the USA.

The following 3 new species of the Philometridae (Nematoda: Dracunculoidea) are described from freshwater centrarchid fishes (Centrarchidae: Perciformes) from eastern North America on the basis of museum and newly collected specimens: Philometra orbitalensis n. sp. and Philometroides aphanonaris n. sp. from the oculo-orbits and subcutaneous tissues of the head, respectively, of the largemouth bass Micropterus salmoides, and Philometroides wellborni n. sp. from the oculo-orbits of the bluegill Lepomis macrochirus (type host) and the redbreast sunfish Lepomis auritus. Whereas P. wellborni is described from both males and gravid females, the males of P. aphanonaris and P. orbitalensis remain unknown. The type locality of all 3 species is the West Point Reservoir, Alabama-Georgia; P. aphanonaris and P. wellborni have also been recorded from the Santee River in South Carolina. In contrast to other Philometra spp. parasitizing North American freshwater fishes, the gravid females of P. orbitalensis are characterized by large cephalic papillae of the external circle, yellowish body color, location (oculo-orbits) in the host, and by the host type (Centrarchidae). Philometroides aphanonaris and P. wellborni differ from North American congeners from freshwater fishes in the absence of esophageal teeth or a different embossment of the caudal end in gravid females; P. wellborni differs from P. aphanonaris in the absence of cuticular bosses from the caudal end of gravid females and in some other features (extent of embossment, body color, location, and host type).

The trithorax group gene moira encodes a brahma-associated putative chromatin-remodeling factor in Drosophila melanogaster.

The genes of the trithorax group (trxG) in Drosophila melanogaster are required to maintain the pattern of homeotic gene expression that is established early in embryogenesis by the transient expression of the segmentation genes. The precise role of each of the diverse trxG members and the functional relationships among them are not well understood. Here, we report on the isolation of the trxG gene moira (mor) and its molecular characterization. mor encodes a fruit fly homolog of the human and yeast chromatin-remodeling factors BAF170, BAF155, and SWI3. mor is widely expressed throughout development, and its 170-kDa protein product is present in many embryonic tissues. In vitro, MOR can bind to itself and it interacts with Brahma (BRM), an SWI2-SNF2 homolog, with which it is associated in embryonic nuclear extracts. The leucine zipper motif of MOR is likely to participate in self-oligomerization; the equally conserved SANT domain, for which no function is known, may be required for optimal binding to BRM. MOR thus joins BRM and Snf5-related 1 (SNR1), two known Drosophila SWI-SNF subunits that act as positive regulators of the homeotic genes. These observations provide a molecular explanation for the phenotypic and genetic relationships among several of the trxG genes by suggesting that they encode evolutionarily conserved components of a chromatin-remodeling complex.

Lethal mutations flanking the 68C glue gene cluster on chromosome 3 of Drosophila melanogaster.

We have conducted a genetic analysis of the region flanking the 68C glue gene cluster in Drosophila melanogaster by isolating lethal and semilethal mutations uncovered by deficiencies which span this region. Three different mutagens were used: ethyl methanesulfonate (EMS), ethyl nitrosourea (ENU) and diepoxybutane (DEB). In the region from 68A3 to 68C11, 64 lethal, semilethal, and visible mutations were recovered. These include alleles of 13 new lethal complementation groups, as well as new alleles of rotated, low xanthine dehydrogenase, lethal(3)517 and lethal(3)B76. Six new visible mutations from within this region were recovered on the basis of their reduced viability; all proved to be semiviable alleles of lethal complementation groups. No significant differences were observed in the distributions of lethals recovered using the three different mutagens. Each lethal was mapped on the basis of complementation with overlapping deficiencies; mutations that mapped within the same interval were tested for complementation, and the relative order of the lethal groups within each interval was determined by recombination. The cytological distribution of genes within the 68A3-68C11 region is not uniform: the region from 68A2,3 to 68B1,3 (seven to ten polytene chromosome bands) contains at least 13 lethal complementation groups and the mutation low xanthine dehydrogenase; the adjoining region from 68B1,3 to 68C5,6 (six to nine bands) includes the 68C glue gene cluster, but no known lethal or visible complementation groups; and the interval from 68C5,6 to 68C10,11 (three to five bands) contains at least three lethal complementation groups and the visible mutation rotated. The developmental stage at which lethality is observed was determined for a representative allele from each lethal complementation group.

The 3' regulatory region of the Abdominal-B gene: genetic analysis supports a model of reiterated and interchangeable regulatory elements.

The Abdominal-B (Abd-B) gene is one of three genes in the bithorax complex, a cluster of homeotic genes in Drosophila. During embryogenesis Abd-B is expressed in a complex pattern, producing four different transcript classes, each of which exhibits a unique spatial pattern of expression. Proper regulation of the class A transcripts is required for appropriate development of the fifth through eighth abdominal segments and is mediated, in part, by a 60-kb regulatory region located 3' of the gene. We have isolated a new mutation, designated Abd-BCorset, which is caused by a deletion that leaves 15 kb of the 3' regulatory sequences immediately adjacent to the gene, but removes 45 kb of the more distant 3' regulatory elements. This mutation produces an unexpected homeotic segmental transformation of the fourth through seventh abdominal segments, and has been analyzed by genetic and molecular techniques. In situ hybridization to Abd-BCorset embryos shows a uniform and moderate level of the Abd-B class A transcript in the posterior abdomen, rather than the normal graded pattern of expression. Our analysis of the Abd-BCorset mutation has prompted a model of the 3' regulatory region of Abd-B based on reiterated cell type-specific elements controlled by adjacent position-sensitive activating elements. The gradient of Abd-B expression normally observed in the posterior abdomen appears to be achieved by varying the number of reiterated elements that are active in each segment.

Topical tretinoin enhances corticosteroid-induced inhibition of tumorigenesis in hairless mice previously exposed to solar simulating radiation.

The role of retinoids in hairless mouse photocarcinogenesis has been studied extensively but remains controversial. By contrast, the role of corticosteroids has hardly been investigated. Many findings indicate an antagonism between the action of these two drugs. To examine these issues, we irradiated hairless mice thrice weekly for 10 weeks with 1.5 minimal erythema doses of solar simulating radiation (UVB + UVA). In the post-UV period, groups of mice were treated topically for 30 weeks with tretinoin, corticosteroid or emollient vehicle alone or with a sequential combination of corticosteroid and tretinoin. A control group remained topically untreated. All three agents, when used alone, significantly inhibited tumorigenesis. The sequential combination produced the greatest inhibition.

Genetics of ethylene biosynthesis and restriction fragment length polymorphisms (RFLPs) of ACC oxidase and synthase genes in melon ( Cucumis melo L.).

We investigated the genetics of ethylene biosynthesis and its linkage to the RFLPs of the ACC oxidase and synthase genes in melon ( Cucumis melo L.). The results suggested that the A(0) and B(0) fragments of RFLP-MEL1 of the ACC oxidase gene were two alleles from a single locus, as were the B and C fragments of RFLP-MEACS1 of the ACC synthase gene. The B(0) allele seemed to be partially dominant over the A(0) allele, whereas B and C alleles appeared to map to quantitative trait loci (QTLs), which most likely contributed to ethylene production. Both RFLPs were linked to ethylene production rates, but they were not linked to each other. The interaction effects of the ACC oxidase and synthase genes on ethylene production were revealed by segregation of RFLP-MEL1 and RFLP-MEACS1. The results of single-copy-reconstruction assays suggested that the ACC oxidase gene is a single copy, whereas the ACC synthase gene is a component of a multigene family in the melon genome. The abscission phenotype appeared to be controlled by an independent locus, with the abscission (full-slip) allele dominant over the non-abscission (not full-slip) allele. These results may facilitate efforts toward mapping the quantitative trait loci (QTLs) of ethylene production. The RFLPs may be used in marker-assisted selection in developing melons with a more-desirable low ethylene production rate for enhancing postharvest storage life.

Mandatory parental involvement/judicial bypass laws: do they promote adolescents' health?

Laws mandating parental involvement in the abortion decisions of pregnant adolescents exist in contrast to "medical emancipation" laws permitting competent minors to consent to their own care. Mandatory parental involvement laws have been the subject of extensive litigation. The Constitution of the United States requires states mandating parental consent or notification to offer the option of a "judicial bypass." In court proceedings, mature minors must be permitted to make their own decisions. Parental involvement/judicial bypass laws, when implemented, have failed to promote family consultation and have had adverse consequences for the pregnant adolescents they affect. States are permitted but not required by the federal Constitution to enact parental involvement/judicial bypass laws. Courts have prevented some of these laws from taking effect based on privacy guarantees in state constitutions. A few states have enacted alternative laws to ensure careful decision making and appropriate family or adult guidance and support.

Fish mortality in the Mississippi catfish farming industry in 1988: causes and treatments.

The 1988 fish mortality summary for the catfish (Ictalurus punctatus) industry in Mississippi is presented. In 1988, 2,456 cases were submitted to Mississippi Cooperative Extension Service fish disease laboratories at Belzoni and Stoneville. Bacterial infection caused by Edwardsiella ictaluri was the leading cause of catfish mortality. Descriptions and treatments are presented for bacterial, parasitic, viral and other diseases affecting Mississippi farm-raised catfish in 1988.

Relationships between the shedding of Coxiella burnetii, clinical signs and serological responses of 34 sheep.

Two abortions associated with Coxiella burnetii occurred in a group of 34 pregnant ewes. The seroprevalence of C. burnetii infection was studied by using an ELISA and the immunofluorescence (IF) assay was applied to the contents of vaginal swabs. In addition, a PCR assay, with primers based on a transposon-like repetitive region of the C. burnetii genome (trans-PcR), was used for the highly sensitive and specific detection of C. burnetii in vaginal swabs, milk and faeces. Of the 34 animals tested at parturition, eight (24 per cent) were positive by ELISA, 11 (32 per cent) were positive by IF, and 15 (44 per cent) were positive when the vaginal swab extract was subjected to the trans-PCR assay. C. burnetii was therefore detected by PCR in the vaginal swabs of seven seronegative ewes. However, five weeks after lambing, 16 (47 per cent) of the animals tested were ELISA positive but only two animals (6 per cent) were positive by PCR. Among the ELISA- and PCR-positive animals, eight (25 per cent) shed coxiella in their milk and six (18 per cent) did so in their faeces.

Human temporomandibular joint eminence shape and load minimization.

Analysis of previous data suggested the hypothesis that temporomandibular joint (TMJ) eminence shapes develop ideally to minimize joint loads. Hence, we tested this hypothesis in nine females and eight males in each of two groups, with and without TMJ disc displacement. Participants provided anatomical data used in a joint load minimization numerical model to predict, and jaw-tracking data used to measure, eminence shapes. Coordinate data (x,y) of shapes were fit to third-order polynomials for two sessions, sides, and methods (predicted, measured) for each participant. Inter-session data were reliable and averaged. Those with, compared with those without, disc displacement had higher measured shape range (5:1) and left-right asymmetry prevalence (4:1). In 29 symmetrical individuals, ANCOVA and Bonferroni tests compared vertical dimensions (y) at 11 postero-anterior points (x), 0.5 mm apart. Model-predicted and measured shapes were significantly different (P < or = 0.01) near the eminence crest, but joint load minimization was consistent with eminence shape for x < 3.0 mm.