DNA binding study of isophorone in rats and mice

Following isophorone exposure, in a 2-year study with F344 rats and B6C3F1 mice performed under the National Toxicology Program (NTP), an elevated incidence of tumors was observed in male rats (kidney tumors) and male mice (liver tumors). Female rats and mice showed no elevation of tumor rates by isophorone (NTP 1986).

The effect of the histological properties of tumors on transfection efficiency of electrically assisted gene delivery to solid tumors in mice

Uniform DNA distribution in tumors is a prerequisite step for high transfection efficiency in solid tumors. To improve the transfection efficiency of electrically assisted gene delivery to solid tumors in vivo, we explored how tumor histological properties affected transfection efficiency. In four different tumor types (B16F1, EAT, SA-1 and LPB), proteoglycan and collagen content was morphometrically analyzed, and cell size and cell density were determined in paraffin-embedded tumor sections under a transmission microscope. To demonstrate the influence of the histological properties of solid tumors on electrically assisted gene delivery, the correlation between histological properties and transfection efficiency with regard to the time interval between DNA injection and electroporation was determined. Our data demonstrate that soft tumors with larger spherical cells, low proteoglycan and collagen content, and low cell density are more effectively transfected (B16F1 and EAT) than rigid tumors with high proteoglycan and collagen content, small spindle-shaped cells and high cell density (LPB and SA-1). Furthermore, an optimal time interval for increased transfection exists only in soft tumors, this being in the range of 5-15 min. Therefore, knowledge about the histology of tumors is important in planning electrogene therapy with respect to the time interval between DNA injection and electroporation.

Enhancement of the chemoprotective enzymes glucuronosyl transferase and glutathione transferase in specific organs of the rat by the coffee components kahweol and cafestol

The coffee components kahweol and cafestol (K/C) have been reported to protect the colon and other organs of the rat against the formation of DNA adducts by 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) and aflatoxin B1. PhIP is a cooked-food mutagen to which significant human exposure and a role in colon cancer etiology are attributed, and, interestingly, such cancers appear to develop at a lower rate in consumers of coffees with high amounts of K/C. Earlier studies in rodent liver have shown that a key role in the chemopreventive effect of K/C is likely to be due to the potential of these compounds to induce the detoxification of xenobiotics by glutathione transferase (GST) and to enhance the synthesis of the corresponding co-factor glutathione. However, mutagens like PhIP may also be detoxified by UDP-glucuronosyl transferase (UDPGT) for which data are lacking regarding a potential effect of K/C. Therefore, in the present study, we investigated the effect of K/C on UDPGT and, concomitantly, we studied overall GST and the pattern of individual GST classes, particularly GST-θ, which was not included in earlier experiments. In addition, we analyzed the organ-dependence of these potentially chemopreventive effects. K/C was fed to male F344 rats at 0.122% in the chow for 10 days. Enzyme activities in liver, kidney, lung, colon, salivary gland, pancreas, testis, heart and spleen were quantified using five characteristic substrates and the hepatic protein pattern of GST classes α, μ, and π was studied with affnity chromatography/HPLC. Our study showed that K/C is not only capable of increasing overall GST and GST classes α, μ, and π but also of enhancing UDGPT and GST-θ. All investigated K/C effects were strongest in liver and kidney, and some response was seen in lung and colon but none in the other organs. In summary, our results show that K/C treatment leads to a wide spectrum of increases in phase II detoxification enzymes. Notably, these effects occurred preferentially in the well perfused organs liver and kidney, which may thus not only contribute to local protection but also to anti-carcinogenesis in distant, less stimulated organs such as the colon.

Influence of cytochrome P-450 inhibitors on the inhalative uptake of methyl chloride and methylene chloride in male B6C3F1 mice

Dichloromethane (DCM) is thought to be metabolized in vivo by two independent pathways: a glutathione (GSH) dependent pathway that yields CO2 and a cytochrome P-450 mediated one that yields both CO and CO2 (Gargas et al 1986). With a physiologically based pharmacokinetic (PB-PK) model, Andersen et al (1987) calculate the quantitative parameters for both metabolic pathways. Using the kinetic parameters thus obtained and the results of two carcinogenicity studies with rodents (Serota et al 1986; NTP 1985), the authors then estimate the tumour risk for humans.

Determination of glutathione transferase (GSTT1-1) activities in different tissues based on formation of radioactive metabolites using 35S-glutathione

A new system has been developed to determine enzyme activities of glutathione transferase θ (GSTT1-1) based on radiometric product detection resulting from the enzymic reaction of methyl chloride with 35S-labelled glutathione. In principle, the method is universally applicable for determination of glutathione transferase activities towards a multiplicity of substrates. The method distinguishes between erythrocyte GSTT1-1 activities of human 'non-conjugators', 'low conjugators' and 'high conjugators'. Application to cytosol preparations of livers and kidneys of male and female Fischer 344 and B6C3F1 mice reveals differential GSTT1-1 activities in hepatic and renal tissues. These ought to be considered in species-specific modellings of organ toxicities of chlorinated hydrocarbons.

Fischer rats consume 20% ethanol in a long-term intermittent-access two-bottle-choice paradigm

The 20% ethanol intermittent-access (IAE) two-bottle-choice drinking procedure has been shown to produce high voluntary ethanol consumption in a number of rat strains. For this study, we applied this procedure to male Fischer (F344) rats, a strain previously reported to exhibit low levels of ethanol consumption. We also subjected these animals to a two-week ethanoldeprivation- period to see if they would exhibit an alcohol deprivation effect (ADE) signified by a transient increase in alcohol consumption following deprivation. Our data show a separation between high and low consuming animals within this strain, with high-consumers exhibiting an escalation in consumption. In contrast, Fischer rats did not show a significant separation between high and low consumers or any significant escalation in consumption, using the 20% ethanol continuous-access two-bottle-choice drinking protocol. Following the two-week deprivation period, animals in the high (but not the low) IAE group exhibited the transient increase in ethanol consumption and preference typically associated with an ADE. Together, the data suggest that the intermittent access protocol is a useful protocol for increasing ethanol consumption.

Strains as Mediators between Job Characteristics and Work-Related Outcomes in Police Officers

The relationship between job characteristics (e.g., job demands, social support) and work-related outcomes (e.g., turnover intentions, job performance) is assumed to be mediated by strains (e.g., work-related well-being, psychological strain). However, evidence suggests this association will be stronger for work-related strains than broader measures of overall psychological well-being. The primary aim of this study was to identify whether work and non-work related strains differ significantly in their ability to mediate between job characteristics and work-related outcomes. Perceptions of job characteristics, strain, turnover intentions and job performance were collected via a self-report survey from 2,588 Australian police officers. All job characteristics (job demands, job control, supervisor support and colleague support) were significant predictors of both job performance and turnover intentions, with the exception of job demands, which was not a significant predictor of turnover intentions. Both work and non-work related strains were significant predictors of turnover intentions and job performance. Strains were collectively significant in mediating between job characteristics and work-related outcomes, except in the case of job demands and job performance. The indirect effects of job characteristics on work-related outcomes were primarily through officers’ work-related enthusiasm. The relative importance of work-related enthusiasm in mediating between job characteristics and work-related outcomes offers some support for previous research suggesting stronger associations between work-related constructs. Future research should examine whether there are substantial differences in the explanatory power of work-related enthusiasm and a popular related construct, work engagement.

Prevalence of Staphylococcus aureus strains in an Australian cohort, 1989-2003 : evidence for the low prevalence of the toxic shock toxin and Panton-Valentine leukocidin genes

The purpose of this paper is to determine the prevalence of the toxic shock toxin gene (tst) and to enumerate the circulating strains of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in Australian isolates collected over two decades. The aim was to subtype these strains using the binary genes pvl, cna, sdrE, pUB110 and pT181. Isolates were assayed using real-time polymerase chain reaction (PCR) for mecA, nuc, 16 S rRNA, eight single-nucleotide polymorphisms (SNPs) and for five binary genes. Two realtime PCR assays were developed for tst. The 90 MRSA isolates belonged to CC239 (39 in 1989, 38 in 1996 and ten in 2003), CC1 (two in 2003) and CC22 (one in 2003). The majority of the 210 MSSA isolates belonged to CC1 (26), CC5 (24) and CC78 (23). Only 18 isolates were tst-positive and only 15 were pvl-positive. Nine MSSA isolates belonged to five binary types of ST93, including two pvlpositive types. The proportion of tst-positive and pvl-positive isolates was low and no significant increase was demonstrated. Dominant MSSA clonal complexes were similar to those seen elsewhere, with the exception of CC78. CC239 MRSA (AUS-2/3) was the predominant MRSA but decreased significantly in prevalence, while CC22 (EMRSA-15) and CC1 (WA-1) emerged. Genetically diverse ST93 MSSA predated the emergence of ST93- MRSA (the Queensland clone).

Nasal carriage of Staphylococcus aureus, including community-associated methicillin-resistant strains, in Queensland adults

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are emerging in southeast Queensland, Australia, but the incidence of carriage of CA-MRSA strains is unknown. The aim of this study was to assess the nasal carriage rate of S. aureus, including CA-MRSA strains, in the general adult population of southeast Queensland. 396 patients presenting to general practices in two Brisbane suburbs and 303 volunteers randomly selected from the electoral rolls in the same suburbs completed a medical questionnaire and had nasal swabs performed for S. aureus. All isolates of S. aureus underwent antibiotic susceptibility testing and single-nucleotide polymorphism (SNP) and binary typing, including determination of Panton–Valentine leukocidin (PVL). The nasal carriage rate of methicillin-susceptible S. aureus (MSSA) was 202/699 (28%), a rate similar to that found in other community-based nasal carriage studies. According to multivariate analysis, nasal carriage of S. aureus was associated with male sex, young adult age group and Caucasian ethnicity. Only two study isolates (one MSSA and one CA-MRSA) carried PVL. The nasal carriage rate of MRSA was low, at 5/699 (0.7%), and only two study participants (0.3%) had CA-MRSA strains. CA-MRSA is an emerging cause of infection in southeast Queensland, but as yet the incidence of carriage of CA-MRSA in the general community is low.

Structural and cellular features in metaphyseal and diaphyseal periosteum of osteoporotic rats

Despite the important physiological role of periosteum in the pathogenesis and treatment of osteoporosis, little is known about the structural and cellular characteristics of periosteum in osteoporosis. To study the structural and cellular differences in both diaphyseal and metaphyseal periosteum of osteoporotic rats, samples from the right femur of osteoporotic and normal female Lewis rats were collected and tissue sections were stained with hematoxylin and eosin, antibodies or staining kit against tartrate resistant acid phosphatase (TRAP), alkaline phosphatase (ALP), vascular endothelial growth factor (VEGF), von Willebrand (vWF), tyrosine hydroxylase (TH) and calcitonin gene-related peptide (CGRP). The results showed that the osteoporotic rats had much thicker and more cellular cambial layer of metaphyseal periosteum compared with other periosteal areas and normal rats (P\0.001). The number of TRAP? osteoclasts in bone resorption pits, VEGF? cells and the degree of vascularization were found to be greater in the cambial layer of metaphyseal periosteum of osteoporotic rats (P\0.05), while no significant difference was detected in the number of ALP? cells between the two groups. Sympathetic nerve fibers identified by TH staining were predominantly located in the cambial layer of metaphyseal periosteum of osteoporotic rats. No obvious difference in the expression of CGRP between the two groups was found. In conclusion, periosteum may play an important role in the cortical bone resorption in osteoporotic rats and this pathological process may be regulated by the sympathetic nervous system.

Effects of lead exposure on hippocampal metabotropic glutamate receptor subtype 3 and 7 in developmental rats

Background A complete explanation of the mechanisms by which Pb2+ exerts toxic effects on developmental central nervous system remains unknown. Glutamate is critical to the developing brain through various subtypes of ionotropic or metabotropic glutamate receptors (mGluRs). Ionotropic N-methyl-D-aspartate receptors have been considered as a principal target in lead-induced neurotoxicity. The relationship between mGluR3/mGluR7 and synaptic plasticity had been verified by many recent studies. The present study aimed to examine the role of mGluR3/mGluR7 in lead-induced neurotoxicity. Methods Twenty-four adult and female rats were randomly selected and placed on control or 0.2% lead acetate during gestation and lactation. Blood lead and hippocampal lead levels of pups were analyzed at weaning to evaluate the actual lead content at the end of the exposure. Impairments of short -term memory and long-term memory of pups were assessed by tests using Morris water maze and by detection of hippocampal ultrastructural alterations on electron microscopy. The impact of lead exposure on mGluR3 and mGluR7 mRNA expression in hippocampal tissue of pups were investigated by quantitative real-time polymerase chain reaction and its potential role in lead neurotoxicity were discussed. Results Lead levels of blood and hippocampi in the lead-exposed rats were significantly higher than those in the controls (P < 0.001). In tests using Morris Water Maze, the overall decrease in goal latency and swimming distance was taken to indicate that controls had shorter latencies and distance than lead-exposed rats (P = 0.001 and P < 0.001 by repeated-measures analysis of variance). On transmission electron microscopy neuronal ultrastructural alterations were observed and the results of real-time polymerase chain reaction showed that exposure to 0.2% lead acetate did not substantially change gene expression of mGluR3 and mGluR7 mRNA compared with controls. Conclusion Exposure to lead before and after birth can damage short-term and long-term memory ability of young rats and hippocampal ultrastructure. However, the current study does not provide evidence that the expression of rat hippocampal mGluR3 and mGluR7 can be altered by systemic administration of lead during gestation and lactation, which are informative for the field of lead-induced developmental neurotoxicity noting that it seems not to be worthwhile to include mGluR3 and mGluR7 in future studies. Background

Differentiation of Rice Tungro Bacilliform Virus Strains by Restriction Analysis and DNA Hybridization

Rice tungro bacilliform virus (RTBV) is one of the two viruses that cause tungro disease. Four RTBV strains maintained in the greenhouse for 4 years, G1, G2, Ic, and L, were differentiated by restriction fragment length polymorphism (RFLP) analysis of the native viral DNA. Although strains G1 and Ic had identical restriction patterns when cleaved with Pst1, BamHI, EcoRI, and EcoRV, they can be differentiated from strains G2 and L by EcoRI and EcoRV digestion. These same endonucleases also differentiate strain G2 from strain L. When total DNA extracts from infected plants were used instead of viral DNA, and digested with EcoRV, identical restriction patterns for each strain (G2 and L) were obtained from roots, leaves, and leaf sheaths of infected plants. The restriction patterns were consistent from plant to plant, in different varieties, and at different times after inoculation. This technique can be used to differentiate RTBV strains and determine the variability of a large number of field samples.

Improved design method for biosecurity surveillance and early detection of non-indigenous rats

A recent advance in biosecurity surveillance design aims to benefit island conservation through early and improved detection of incursions by non-indigenous species. The novel aspects of the design are that it achieves a specified power of detection in a cost-managed system, while acknowledging heterogeneity of risk in the study area and stratifying the area to target surveillance deployment. The design also utilises a variety of surveillance system components, such as formal scientific surveys, trapping methods, and incidental sightings by non-biologist observers. These advances in design were applied to black rats (Rattus rattus) representing the group of invasive rats including R. norvegicus, and R. exulans, which are potential threats to Barrow Island, Australia, a high value conservation nature reserve where a proposed liquefied natural gas development is a potential source of incursions. Rats are important to consider as they are prevalent invaders worldwide, difficult to detect early when present in low numbers, and able to spread and establish relatively quickly after arrival. The ‘exemplar’ design for the black rat is then applied in a manner that enables the detection of a range of non-indigenous species of rat that could potentially be introduced. Many of the design decisions were based on expert opinion as data gaps exist in empirical data. The surveillance system was able to take into account factors such as collateral effects on native species, the availability of limited resources on an offshore island, financial costs, demands on expertise and other logistical constraints. We demonstrate the flexibility and robustness of the surveillance system and discuss how it could be updated as empirical data are collected to supplement expert opinion and provide a basis for adaptive management. Overall, the surveillance system promotes an efficient use of resources while providing defined power to detect early rat incursions, translating to reduced environmental, resourcing and financial costs.