Chromosomal evolution of Arvicolinae (Cricetidae, Rodentia). II. The genome homology of two mole voles (genus Ellobius), the field vole and golden hamster revealed by comparative chromosome painting

Using cross-species chromosome painting, we have carried out a comprehensive comparison of the karyotypes of two Ellobius species with unusual sex determination systems: the Transcaucasian mole vole, Ellobius lutescens (2n = 17, X in both sexes), and the northern mole vole, Ellobius talpinus (2n = 54, XX in both sexes). Both Ellobius species have highly rearranged karyotypes. The chromosomal paints from the field vole (Microtus agrestis) detected, in total, 34 and 32 homologous autosomal regions in E. lutescens and E. talpinus karyotypes, respectively. No difference in hybridization pattern of the X paint (as well as Y paint) probes on male and female chromosomes was discovered. The set of golden hamster (Mesocricetus auratus) chromosomal painting probes revealed 44 and 43 homologous autosomal regions in E. lutescens and E. talpinus karyotypes, respectively. A comparative chromosome map was established based on the results of cross-species chromosome painting and a hypothetical ancestral Ellobius karyotype was reconstructed. A considerable number of rearrangements were detected; 31 and 7 fusion/fission rearrangements differentiated the karyotypes of E. lutescens and E. talpinus from the ancestral Ellobius karyotype. It seems that inversions have played a minor role in the genome evolution of these Ellobius species.     

Enhancement of peroxisomal enzymes, cytochrome P-452 and DNA synthesis in putative preneoplastic foci of rat liver treated with the peroxisome proliferator nafenopin

The peroxisome proliferator (PP) nafenopin (NAF) enhanced tumordevelopment in rat liver through promotion of a subtype of putativepreneoplastic cell foci, characterized by weak cytoplasmic basophilia(1,2). In order to elucidate the selective growth advantageof these weakly basophilic foci (WBF) we investigated the effectsof NAF on their metabolic phenotype and DNA synthesis. In WBF,as well as in other foci subpopulations and in hepatocellularcarcinomas the occurrence of five NAF-inducible enzymes, i.e.of peroxisomal ß-oxidation (acyl-CoA oxidase, bifunctionalprotein and thiolase), catalase and cytochrome P-452 was studiedby immunohistochemical methods. In untreated livers almost allfoci were stained with the same intensity as the surroundingtissue. When NAF was applied, most of the liver foci showedconsiderably less staining than the non-focal parenchyma inwhich pronounced enzyme induction had occurred. However, thesubpopulation of WBF showed a more heterogeneous pattern ofenzyme expression varying from less to even more than in theadjacent tissue. A similarly broad range of expression of peroxisomalenzymes was found in hepatocellular carcinomas. On average,however, the tumors exhibited less staining and lower activityof peroxisomal ß-oxidation than the surrounding parenchyma.WBF always showed higher rates of DNA synthesis than other focisubtypes and unaltered liver. In     

Continuous in vitro cultivation of erythrocytic stages ofBabesia equi

The protozoan parasiteBabesia equi, a causative agent of equine piroplasmosis, was continuously cultivated in horse erythrocytes. The parasites were isolated from a carrier horse at a time when no parasite was detected in a thin blood smear. The culture medium consisted of modified medium 199 supplemented with 40% non-heat-inactivated horse serum in a humidified atmosphere containing 5% CO₂, 2% O₂, and 93% N₂ at 37° C. Parasites were detected after 2 days in culture. When the percentage of parasitized erytrrocytes (PPE) reached 1%, the cultures were transferred into a humidified atmosphere of 5% CO₂ in air. After 7 days the cultures were split at a ratio of 12, and after another 5 days they were split at a ratio of 14. From them on, cultures were split at a ratio of 14 routinely at 2-day intervals. The PPE ranged between 10% and 25%. Supplementation with hypoxanthine was essential for the initiation and propagation of cultures. In established cultures, hypoxanthine could be replaced by equimolar concentrations of adenosine or guanosine. Parasites from cultures could be cryopreserved and resuscitated. Cultures were maintained for more than 300 days.     

Galanin influences the mechanosensitivity of sensory endings in the rat knee joint

The aim of the present study was to examine the effect of galanin on group III and IV afferent nerve fibres (n = 53) innervating normal and acutely inflamed knee joints in rats. They responded to local mechanical stimulation, movements of the joint and i.a. injections of KCl close to the joint. Single i.a. bolus injections of galanin (0.1 mM, 0.2 mL) caused no direct responses of the units. In normal and acutely inflamed joints, about half of the units did not change the responses to knee joint rotation. A significant reduction of the responses to noxious movements was found in approximately 40% of the units reaching a mean value of 57% in normal joints and 70% in inflamed joints compared with control movements. In approximately 10% the responses increased to 143% in normal joints and 120% in inflamed joints. Injection of a galanin receptor antagonist (M35) doubled the responses to noxious movements in 36% of the units in normal joints and reduced it in 18% to 86% of the control movements, indicating a tonic release and influence on the mechanosensitivity of a proportion of primary afferents by galanin. In conclusion, these data further support the hypothesis that the mechanosensitivity of fine afferent nerve fibres is regulated by a mixture of different substances being released into the innervated tissue. Besides the action of several pro-inflammatory peptides there seems to exist a tonic inhibitory system.     

Respiratory exposure to diesel exhaust particles decreases the spleen IgM response to a T cell-dependent antigen in female B6C3F1 mice.

We investigated the systemic immunotoxic potential of respiratory exposure to diesel exhaust particles (DEP) in this study. Female B6C3F1 mice (approximately 8 weeks old) were exposed to increasing concentrations of DEP intratracheally, 3 times every two weeks, and sacrificed 2 or 4 weeks after the first exposure. The systemic toxicity and immune status in mice were evaluated. Mice exposed to DEP (1 to 15 mg/kg) showed no significant changes in body, spleen, or liver weights. Lung weights were increased in the mice exposed to 15 mg/kg DEP for 2 or 4 weeks. Except for a decreased platelet count, no significant alterations occurred in hematological parameters following DEP exposure. The number of splenic anti-sheep red blood cell (sRBC) IgM antibody-forming cells (AFC) decreased following DEP exposure for 2 weeks. This effect was less severe following 4 weeks of exposure and was only evident in the high dose group. Exposure to DEP also resulted in a significant decrease in the absolute numbers and the percentages of total spleen cells for total, CD4(+), and CD8(+) T cells, while the numbers of B cells and total nucleated cells in spleen were not significantly changed. The proliferative response of splenocytes to the T-cell mitogen, concanavalin A (ConA), as well as their production of IL-2 and IFN-gamma, was decreased dose-dependently following exposure of mice to DEP for 2 weeks, whereas proliferation was not changed in response to anti-CD3 monoclonal antibody. In summary, short-term respiratory exposure of mice to DEP resulted in systemic immunosuppression with evidence of T cell-mediated and possibly macrophage-mediated mechanisms.     

Responses of fine primary afferent nerve fibres innervating the rat knee joint to defined torque

In total 23 rat knee joint afferent units with conduction velocities of 1.2-17 m/s were recorded extracellularly during inward and outward joint rotations of defined torque using a newly developed torque-meter. There was not a linear relation between the torque and the obtained angle of the joint. The mechanical thresholds of the units ranged from 10 to 60 mNm. During 10 s of stimulation with 60 mNm they responded with 12-300 action potentials. Two mechanosensitive nerve fibres could not be activated via knee joint rotation at any torque at all. The units could be classified according to their response pattern during stimulation: (1) phasic-tonic response behaviour; (2) constant discharge rate; (3) delayed onset of activity. In conclusion, the novel torque-meter allows a precise characterisation of the mechanical threshold and the corresponding response of fine afferent joint units during knee joint rotation.     

Retention and HIV seroconversion among drug users on methadone maintenance treatment in Yunnan,China

Setting: Thirteen methadone maintenance treatment (MMT) clinics across Yunnan, the province with the highest human immunodeficiency virus (HIV) burden in China.Objectives: To determine, among HIV-negative participants on MMT, the proportion lost to follow-up (defined as those who missed the 6-monthly follow-up examination), factors associated with loss to follow-up (LFU), HIV seroconversion rate and factors associated with seroconversion.Design: Prospective cohort study from October 2008 to April 2011. All participants were administered a pre-tested structured questionnaire to capture associated factors and offered HIV testing every 6 months. χ² test and log-binomial regression were used for data analysis.Results: Of 1146 participants, 541 (47%) were lost to follow-up in 2.5 years. Factors associated with higher LFU proportion include <6 months of previous MMT, inconvenient location of the MMT clinic and average methadone dose ⩽60 mg/day, with adjusted relative risks (RRs) of respectively 1.4 (95%CI 1.2–1.5), 1.2 (95%CI 1.0–1.4) and 1.1 (95%CI 1.0–1.3). The overall HIV seroconversion rate was 6.6 (95%CI 3.7–11.0) per 1000 person-years. Not living with a partner contributed to higher HIV rates, with an adjusted RR of 3.6 (95%CI 1.0–12.8).Conclusion: The retention rate of MMT participants in Yunnan was not satisfactory. Decentralising service delivery in the community and making directly observed treatment more convenient has the potential to improve retention.