Effects of environmental enrichment on sensitivity to mu, kappa, and mixed-action opioids in female rats

Several studies report that environmental enrichment enhances sensitivity to opioid receptor agonists in male rats. Very few studies have examined the effects of enrichment in female rats, and thus it is not clear whether females are similarly sensitive to these effects. Consequently, the purpose of the present study was to examine the effects of environmental enrichment on sensitivity to representative mu, kappa, and mixed-action opioids in female rats. Following a protocol established in males, females were obtained at weaning and randomly assigned to two groups immediately upon arrival: isolated rats were housed individually with no visual or tactile contact with other rats; enriched rats were housed in groups of four in large cages and given various novel objects on a regular basis. After 6 weeks under these conditions, the antinociceptive effects of mu (morphine, levorphanol), kappa (spiradoline, U69,593), and mixed-action (buprenorphine, butorphanol) opioids were examined in a warm-water, tail-withdrawal procedure. All the opioids examined produced dose-dependent increases in antinociception; however, no differences in opioid sensitivity were observed between the two groups. To determine whether these findings were consistent across behavioral endpoints, the antidiuretic effects of representative mu opioids, and the diuretic effects of representative kappa opioids, were examined in female rats reared under isolated or enriched conditions for 10 weeks. Similar to that seen in the antinociceptive experiment, no significant differences in opioid sensitivity were observed between groups. These data indicate that environmental enrichment does not alter sensitivity to the effects of opioid receptor agonists in female rats, and suggest that females may respond differently to environmental enrichment than males.     

Wear evaluation of cobalt-chromium alloy for use in a metal-on-metal hip prosthesis

Wear of the polyethylene in total joint prostheses has been a source of morbidity and early device failure, which has been extensively reported in the last 20 years. Although research continues to attempt to reduce the wear of polyethylene joint-bearing surfaces by modifications in polymer processing, there is a renewed interest in the use of metal-on-metal bearing couples for hip prostheses. Wear testing of total hip replacement systems involving the couple of metal or ceramic heads on polymeric acetabular components has been performed and reported, but, until recently, there has been little data published for pin-on-disk or hip-simulator wear studies involving the combination of a metallic femoral head component with an acetabular cup composed of the same or a dissimilar metal. This study investigated the in vitro wear resistance of two cobalt/chromium/molybdenum alloys, which differed primarily in the carbon content, as potential alloys for use in a metal-on-metal hip-bearing couple. The results of pin-on-disk testing showed that the alloy with the higher (0.25%) carbon content was more wear resistant, and this alloy was therefore chosen for testing in a hip-simulator system, which modeled the loads and motions that might be exerted clinically. Comparison of the results of metal-on-polyethylene samples to metal-on-metal samples showed that the volumetric wear of the metal-on-polyethylene bearing couple after 5,000,000 cycles was 110-180 times that for the metal-bearing couple. Polyethylene and metal particles retrieved from either the lubricant for pin-on-disk testing or hip simulator testing were characterized and compared with particles retrieved from periprosthetic tissues by other researchers, and found to be similar. Based upon the results of this study, metal-on-metal hip prostheses manufactured from the high carbon cobalt/chromium alloy that was investigated hold sufficient promise to justify human clinical trials.     

Evaluation of a Diagnostic Algorithm Using Immunoglobulin M Enzyme-Linked Immunosorbent Assay To Differentiate Human West Nile Virus and St. Louis Encephalitis Virus Infections during the 2002 West Nile Virus Epidemic in the United States

A diagnostic algorithm was developed to differentiate between human infections of West Nile virus (WNV) and St. Louis encephalitis virus (SLEV) using positive-to-negative (P/N) ratios derived from the immunoglobulin M capture enzyme-linked immunosorbent assay (MAC-ELISA). To validate this algorithm, we tested 1,418 serum and cerebrospinal fluid (CSF) samples from confirmed WNV and SLEV infections collected during the WNV epidemic of 2002 in the United States. WNV P/N-to-SLEV P/N ratios (W/S ratios) were calculated and used to identify the infecting virus. These results were compared to results from the plaque reduction neutralization test (PRNT), which is currently the standard assay used to discriminate between closely related flavivirus infections. If the W/S ratio was ≥1, the predictive value positive (PNP) for WNV was 97.8%, where 95% of flavivirus cases were due to WNV infection and only 3.7% of specimens would require PRNT to differentiate WNV from SLEV infection. Use of the W/S ratio as part of the testing algorithm to interpret MAC-ELISA results generates reportable probable cases quickly, alleviating the need for PRNT in most instances.     

Slow-cycling therapy-resistant cancer cells

Tumor recurrence after chemotherapy is a major cause of patient morbidity and mortality. Recurrences are thought to be secondary to small subsets of cancer cells that are better able to survive traditional forms of chemotherapy and thus drive tumor regrowth. The ability to isolate and better characterize these therapy-resistant cells is critical for the future development of targeted therapies aimed at achieving more robust and long-lasting responses. Using a novel application for the proliferation marker carboxyfluorescein diacetate, succinimidyl ester (CFSE), we have identified a population of slow-cycling, label-retaining tumor cells in both in vitro sphere cultures and in vivo xenograft models. Strikingly, label-retaining cells exhibit a multifold increase in ability to survive traditional forms of chemotherapy and reenter the cell cycle. Further, we demonstrate the innovative application of CFSE to live sort slow-cycling tumor cells and validate their chemoresistance and tumorigenic potential.     

Genetic variants, immune function, and risk of pre-eclampsia among American Indians

Citation Best LG, Nadeau M, Davis K, Lamb F, Bercier S, Anderson CM. Genetic variants, immune function, and risk of pre‐eclampsia among American Indians. Am J Reprod Immunol 2012; 67: 152–159 Problem To determine the prevalence in an American Indian population of genetic variants with putative effects on immune function and determine if they are associated with pre‐eclampsia (PE). Method of study In a study of 66 cases and 130 matched controls, six single nucleotide polymorphisms (SNP) with either previously demonstrated or postulated modulating effects on the immune system were genotyped. Allele frequencies and various genetic models were evaluated by conditional logistic regression in both univariate and multiply adjusted models. Results Although most genetic variants lacked evidence of association with PE, the minor allele of the CRP related, rs1205 SNP in a dominant model with adjustment for age at delivery, nulliparity, and body mass index, exhibited an odds ratio of 0.259 (95% CI of 0.08–0.81, P = 0.020) in relation to severe PE (48 cases). The allelic prevalence of this variant was 46.1% in this population. Conclusion Of the six SNPs related to immune function in this study, a functional variant in the 3′UTR of the CRP gene was shown to be associated with severe PE in an American Indian population.     

Downregulation of multiple stress defense mechanisms during differentiation of human embryonic stem cells

Evolutionary theory predicts that cellular maintenance, stress defense, and DNA repair mechanisms should be most active in germ line cells, including embryonic stem cells that can differentiate into germ line cells, whereas it would be energetically unfavorable to keep these up in mortal somatic cells. We tested this hypothesis by examining telomere maintenance, oxidative stress generation, and genes involved in antioxidant defense and DNA repair during spontaneous differentiation of two human embryonic stem cell lines. Telomerase activity was quickly downregulated during differentiation, probably due to deacetylation of histones H3 and H4 at the hTERT promoter and deacetylation of histone H3 at hTR promoter. Telomere length decreased accordingly. Mitochondrial superoxide production and cellular levels of reactive oxygen species increased as result of increased mitochondrial biogenesis. The expression of major antioxidant genes was downregulated despite this increased oxidative stress. DNA damage levels increased during differentiation, whereas expression of genes involved in different types of DNA repair decreased. These results confirm earlier data obtained during mouse embryonic stem cell differentiation and are in accordance with evolutionary predictions.     

Substantial intrapatient differences in the breadth and specificity of HIV-specific CD8+ T-cell interferon-gamma and proliferation responses

HIV vaccine design and evaluation require a better understanding of protective immune responses. HIV-specific CD8+ T-cell responses have been characterized extensively using interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot (ELISPOT) assays, which do not always correlate with control of viral replication or disease progression. Alternative aspects of CD8+ T-cell responses, in particular those associated with a central memory (Tcm) phenotype, may be more protective against disease progression. To determine the extent that the breadth and specificity of HIV-specific CD8+ T-cell responses differ based on immunological readout, we screened in HIV-infected Kenyan sex workers for responses to HIV Env using IFN-gamma ELISPOT and 6-day carboxyfluorescein succinimidyl ester-based proliferation assays. This comparison revealed substantial differences in the epitopes recognized when the assay readout was IFN-gamma versus proliferation. Although 24 and 41 IFN-gamma and proliferative responses were identified, overlapping specificity was observed for only 5 responses. Breadth also differed between assays in several patients. Env-specific IFN-gamma breadth was found to correlate inversely with CD4 count (r = -0.66, P = 0.005), although this was not the case for proliferation. These data suggest that efforts to define HIV-specific CD8+ T-cell responses may need to be revisited using additional immunological readouts.     

Isolation of primordial germ cells from differentiating human embryonic stem cells

Of all the cell types that can be obtained from the differentiation of embryonic stem cells, primordial germ cells are arguably the most fascinating, as they represent the in vitro completion of the reproductive cycle of the organism from which the embryonic stem cell line was derived. It is also possible to obtain these cells from embryos at an appropriate stage of development, but this process yields only small numbers that are not applicable to investigations of their epigenetic architecture. A considerable body of data has been generated from the differentiation of mouse embryonic stem cells to this cell type, but despite the demonstration of their presence in human embryoid bodies, there has been little progress toward methods of producing human primordial germ cells in useful numbers. We present here a robust protocol to differentiate two human embryonic stem cell lines (H9 and hES-NCL1) that maximizes the numbers of primordial germ cells that may be obtained using a simple fluorescence-activated cell sorting strategy for their isolation. These primordial germ cells demonstrate high-level expression of the germ cell-specific VASA gene and show removal of parental imprints and chromatin modification changes that support their primordial germ cell identity.