Interindividual variability in the prevalence of OPRM1 and CYP2B6 gene variations may identify drug-susceptible populations

Methadone is used worldwide for the treatment of heroin addiction; however, fatal poisonings are increasingly reported. The prevalence of CYP2B6 and μ-opioid receptor (OPRM1) gene variations were examined between a postmortem population where the deaths were associated with methadone and a live nondrug-using control population using Taqman™ SNP Genotyping assays. The CYP2B6*6 allele was higher in the postmortem population, but the difference was not significant (P = 0.92). The CYP2B6 T750C promoter variation was similar in frequency for both populations. Linkage between T750C and CYP2B6*6 was identified for both populations (P < 0.01). The prevalence of the OPRM1 A118G variation was significantly higher in the control population (P = 0.0046), which might indicate a protective mechanism against opioid toxicity. Individual susceptibility to methadone may be determined by screening for CYP2B6*6.

OPRM1 and CYP2B6 gene variants as risk factors in methadone-related deaths

Methadone is a medication valued for its effectiveness in the treatment of heroin addiction; however, many fatal poisonings associated with its use have been reported over the years. We have examined the association between CYP2B6 and micro-opioid receptor (OPRM1) gene variations and apparent susceptibility to methadone poisoning. Genomic DNA was extracted from postmortem whole blood of 40 individuals whose deaths were attributed to methadone poisoning. The presence of CYP2B6*4,*9, and *6 alleles and the OPRM1 A118G variant was determined by SNP genotyping. CYP2B6 *4, *9, and *6 alleles were found to be associated with higher postmortem methadone concentrations in blood (P < or = 0.05). OPRM1 A118G was also associated with higher postmortem methadone concentrations in blood but not to a level of statistical significance (P = 0.39). In these methadone-related deaths, OPRM1 118GA was associated with higher postmortem benzodiazepine concentrations (P = 0.04), a finding not associated with morphine-related deaths. The risk of a methadone-related fatality during treatment may be evaluated in part by screening for CYP2B6*6 and A118G.

Cloning, expression and immunoassay detection of ferret IFN-gamma

Ferrets (Mustela putorius furo) develop symptoms upon influenza infection that resemble those of humans, including sneezing, body temperature variation and weight loss. Highly pathogenic strains of influenza A, such as H5N1, have the capacity to cause severe illness or death in ferrets. The use of ferrets as a model of influenza infection is currently limited by a lack of species-specific immunological reagents. Interferon gamma (IFN-gamma) plays a key role in the development of innate and adaptive immunity and the regulation of Th1-type immune responses. Here we describe the cloning of the full-length cDNA for ferret IFN-gamma. Multiple sequence alignment of the predicted amino acid sequence with those of other species indicates that the predicted ferret protein shares the highest identity with Eurasian badger IFN-gamma. We raised two hybridoma clones expressing monoclonal antibodies against recombinant ferret IFN-gamma capable of detecting IFN-gamma protein derived from mitogen-stimulated ferret PBMCs by immunoblotting, ELISA and ELISPOT assay. Finally, an ELISA utilizing the ferret-specific antibodies detected elevated levels of IFN-gamma in serum samples from H3N2 influenza A-infected ferrets.

Cloning, expression and characterization of ferret CXCL10

Chemokines and their receptors function in the recruitment and activation of cells of the immune system to sites of inflammation. As such, chemokines play an important role in mediating pathophysiological events during microbial infection. In particular, CXCL9, CXCL10 and CXCL11 and their cognate receptor CXCR3 have been associated with the clinical course of several infectious diseases, including severe acute respiratory syndrome (SARS) and influenza. While CXCL9, CXCL10 and CXCL11 share the same receptor and have overlapping functions, each can also have unique activity in host defense. The lack of a preferred characterized animal model for SARS has brought our attention to ferrets, which have been used for years in influenza studies. The lack of immunological reagents for ferrets prompted us to clone CXCL9, CXCL10, CXCL11 and CXCR3 and, in the case of CXCL10, to express the gene as a recombinant protein. In this study we demonstrate that endogenous ferret CXCL10 exhibits similar mRNA expression patterns in the lungs of deceased SARS patients and ferrets experimentally infected with SARS coronavirus. This study therefore represents an important step towards development of the ferret as a model for the role of CXCL9, CXCL10 and CXCL11:CXCR3 axis in severe viral infections.

Interferon-mediated immunopathological events are associated with atypical innate and adaptive immune responses in patients with severe acute respiratory syndrome

It is not understood how immune inflammation influences the pathogenesis of severe acute respiratory syndrome (SARS). One area of strong controversy is the role of interferon (IFN) responses in the natural history of SARS. The fact that the majority of SARS patients recover after relatively moderate illness suggests that the prevailing notion of deficient type I IFN-mediated immunity, with hypercytokinemia driving a poor clinical course, is oversimplified. We used proteomic and genomic technology to systematically analyze host innate and adaptive immune responses of 40 clinically well-described patients with SARS during discrete phases of illness from the onset of symptoms to discharge or a fatal outcome. A novel signature of high IFN-alpha, IFN-gamma, and IFN-stimulated chemokine levels, plus robust antiviral IFN-stimulated gene (ISG) expression, accompanied early SARS sequelae. As acute illness progressed, SARS patients entered a crisis phase linked to oxygen saturation profiles. The majority of SARS patients resolved IFN responses at crisis and expressed adaptive immune genes. In contrast, patients with poor outcomes showed deviated ISG and immunoglobulin gene expression levels, persistent chemokine levels, and deficient anti-SARS spike antibody production. We contend that unregulated IFN responses during acute-phase SARS may culminate in a malfunction of the switch from innate immunity to adaptive immunity. The potential for the use of the gene signatures we describe in this study to better assess the immunopathology and clinical management of severe viral infections, such as SARS and avian influenza (H5N1), is therefore worth careful examination.

Cell transplantation preserves cardiac function after infarction by infarct stabilization: augmentation by stem cell factor

OBJECTIVE

We hypothesized that implantation of adult mesenchymal stem cells after acute myocardial infarction mobilizes bone marrow precursor cells by activating the stem cell factor pathway, and that overdriving this pathway would enhance the beneficial effects of cell transplantation.

METHODS

After coronary ligation, medium, mesenchymal stem cells, or stem cell factor-overproducing mesenchymal stem cells were injected into the anterior left ventricle. Cells from beta-galactosidase transgenic mice enabled tracking of injected cells. The global and local impact of the cells was evaluated by measuring cytokine levels, endothelial progenitor cells, and myocardial angiogenesis, and by addressing cardiomyogenesis with confocal microscopy. The impact on cardiac function was evaluated by pressure-volume loops. Ventricular morphometrics were measured after in situ perfusion-fixation of the hearts at physiologic pressures.

RESULTS

Implantation of mesenchymal stem cells increased myocardial stem cell factor levels 2.0-fold, endothelial progenitor cell mobilization 2.7-fold, and myocardial angiogenesis 2.3-fold (P < .05), but did not induce mitogenesis in host cardiomyocytes or give rise to beta-galactosidase-expressing cardiomyocytes. Cell-transplanted groups had improved indices of cardiac function, including preload recruitable stroke work and end-systolic elastance (P < .001). Cell transplantation resulted in 2.0-fold smaller ventricular volumes (P = .001) and 2.0-fold reduced infarct scar area (P = .056), but had no effect on the volume of spared myocardium. Stem cell factor overproduction imparted greater functional benefit without inducing detectable histologic cardiomyocyte regeneration.

CONCLUSION

Mesenchymal stem cell implantation after myocardial infarction facilitates functional cardiac regeneration without myocyte regeneration through augmentation of endogenous infarct repair, which is enhanced by stem cell factor.

Therapeutic opportunities for cell cycle re-entry and cardiac regeneration

Over the last two decades, considerable effort has been made to better understand putative regulators and molecular switches that govern the cell cycle in attempts to reactivate cell cycle progression of cardiac muscle. Rapid advancements on the field of stem cycle biology including evidence of cardiac progenitors within the adult myocardium itself and reports of cardiomyocyte DNA synthesis, which each suggest that the adult myocardium may in fact have the capacity for de novo myocyte regeneration. Augmenting cardiomyocyte number by targeting specific cell cycle regulatory genes or by stimulating cardiac progenitor cells to differentiate into cardiac muscle may be of therapeutic value in repopulating the adult myocardium with functionally active cells in patients with end-stage heart failure. Advancements in the area of cardiomyocyte cell cycle control and regeneration and their therapeutic potential are discussed.

Influence of light energy density on effectiveness of composite cure

This study investigated the influence of light energy density (intensity x time) on the effectiveness of composite cure in view of the curing profiles of new light-polymerization units. This investigation used a digital microhardness tester to evaluate the hardness of the top/bottom surfaces and hardness ratio of 2 mm thick composite specimens after exposure to different light energy densities. Parameters included five light intensities (200, 300, 400, 500 and 600 mW/cm2) and nine irradiation times (10, 20, 30, 40, 60, 80, 100, 120 and 180 seconds). Six samples were evaluated for each light energy density. KHN values and the hardness ratio obtained with 40 seconds cure at 400 mW/cm2 was used as control. Results were analyzed with one-way ANOVA and Scheffe's post-hoc test at significance level (0.05). Correlation between curing time and hardness values and ratio was done using Pearson's correlation at significance level 0.01. Results showed that the adequate hardness for surface finishing could be obtained with 20 seconds irradiation at lower intensities of 200 or 300 mW/cm2. Optimal cure of the bottom surfaces could not be achieved with 200 mW/cm2, but was attained with 300 mW/cm2 only after 120 seconds of irradiation. Optimal cure of the bottom surfaces was possible with 30 and 20 seconds irradiation at 500 and 600 mW/cm2, respectively. Effective cure was not achieved with low light intensities (200 to 300 mW/cm2) but could be achieved with high intensities (500 and 600 mW/cm2) after 30 seconds of irradiation.

Chronic treatment with propranolol induces antioxidant changes and protects against ischemia-reperfusion injury

The goal of this study was to examine whether chronic administration of propranolol offers protection against ischemia-reperfusion injury and whether it induces any change in the myocardial endogenous antioxidant enzyme activities and their gene expression. Rats were treated with propranolol (10 mg/kg/day, i.p.) for either 6 or 18 days. Forty-eight h after the last propranolol injection, isolated hearts were subjected to 60 min of global ischemia and 40 min of reperfusion. Resting tension in the control and treated groups after ischemia was 385+/-30 and 150+/-15%; and upon reperfusion was 140+/-11 and 49+/-6%, respectively, as compared to the pre-ischemic values. Recovery of the contractile function in globally ischemic hearts upon reperfusion was about 35% in the treated group as compared to about 16% in the control group at 10 and 20 min. A positive response to catecholamine was observed in hearts from propranolol group (C, 3.41+/-0.36; epi, 6.03+/-0.47 g/g) and was comparable to control hearts (C, 3.55+/-0.31; epi, 6.48+/-0.42 g/g). Myocardial antioxidants, catalase and glutathione peroxidase enzyme activities, in the treated group, prior to ischemia-reperfusion were increased by 67+/-9 and 45+/-11%, respectively, over those in controls. Superoxide dismutase activity did not show any change. The mRNA expression for the three antioxidant enzymes did not change in the hearts of the treated group as compared to control. Lipid peroxidation, both before and after the ischemia-reperfusion episode, was significantly reduced in the propranolol-treated hearts compared to the control group. Hearts studied at the end of reperfusion showed no difference in enzyme activities between treated and control groups. These data show that propranolol treatment of the animals protects against ischemia-reperfusion injury in isolated hearts in the absence of beta-blockade. Increased endogenous antioxidant enzyme activities due to propranolol treatment may have a role in this protection.

Probucol treatment reverses antioxidant and functional deficit in diabetic cardiomyopathy

Earlier we reported that probucol treatment subsequent to the induction of diabetes can prevent diabetes-associated changes in myocardial antioxidants as well as function at 8 weeks. In this study, we examined the efficacy of probucol in the reversal of diabetes induced myocardial changes. Rats were made diabetic with a single injection of streptozotocin (65 mg/kg, i.v.). After 4 weeks of induction of diabetes, a group of animals was treated on alternate days with probucol (10 mg/kg i.p.), a known lipid lowering agent with antioxidant properties. At 8 weeks, there was a significant drop in the left ventricle (LVSP) and aortic systolic pressures (ASP) in the diabetic group. Hearts from these animals showed an increase in the thiobarbituric acid reacting substances (TBARS), indicating increased lipid peroxidation. This was accompanied by a decrease in the myocardial antioxidant enzymes activities, superoxide dismutase (SOD) and glutathione peroxidase (GSHPx). Myocardial catalase activity in the diabetic group was higher. In the diabetic + probucol group both LVSP and ASP showed significant recovery. This was also accompanied by an improvement in SOD and GSHPx activities and there was further increase in the catalase activity. Levels of the TBARS was decreased in this group. These data provide evidence that diabetic cardiomyopathy is associated with an antioxidant deficit which can be reversed with probucol treatment. Improved cardiac function with probucol may be due to the recovery of antioxidants in the heart.

Oxidative stress and heart failure

Various abnormalities have been implicated in the transition of hypertrophy to heart failure but the exact mechanism is still unknown. Thus heart failure subsequent to hypertrophy remains a major clinical problem. Recently, oxidative stress has been suggested to play a critical role in the pathogenesis of heart failure. Here we describe antioxidant changes as well as their significance during hypertrophy and heart failure stages. Heart hypertrophy in rats and guinea pigs, in response to pressure overload, is associated with an increase in 'antioxidant reserve' and a decrease in oxidative stress. Hypertrophied rat hearts show increased tolerance for different oxidative stress conditions such as those imposed by free radicals, hypoxia-reoxygenation and ischemia-reperfusion. On the other hand, heart failure under acute as well as chronic conditions is associated with reduced antioxidant reserve and increased oxidative stress. The latter may have a causal role as suggested by the protection seen with antioxidant treatment in acute as well as in chronic heart failure. It is becoming increasingly apparent that, anytime the available antioxidant reserve in the cell becomes inadequate, myocardial dysfunction is imminent.

Enhanced expression of insulin-like growth factor-binding protein-I in the fasted rat: the effects of insulin and growth hormone administration

The effect of fasting on insulin-like growth factor-binding protein-1 (IGFBP-1) expression was examined in the rat. Food deprivation for a period of 24 h resulted in a 9.5 +/- 2.0-fold increase in hepatic IGFBP-1 mRNA abundance (P less than 0.001). An increase in circulating IGFBP-1 in sera from fasted rats was demonstrated by immunoblotting, and an increased abundance of a 30-kDa IGFBP in sera from fasted rats was apparent when [125I]IGF-I was used in ligand blotting experiments. Refeeding resulted in a prompt decline in hepatic IGFBP-1 mRNA. Administration of insulin (0.5-4 U, ip) to fasted rats resulted in profound hypoglycemia, but either increased or had no significant effect on hepatic IGFBP-1 mRNA abundance. In contrast, administration of human GH (hGH; 100 micrograms, ip) resulted in a prompt decline in hepatic IGFBP-1 mRNA, followed by a late rebound in IGFBP-1 mRNA to levels greater than those in fasted controls. Furthermore, hepatic IGFBP-1 mRNA levels were significantly lower in hGH-treated (100 micrograms every 8 h) food-deprived rats than in saline-treated food-deprived rats (2.25 +/- 1.55- vs. 8.99 +/- 3.80-fold increase; P less than 0.005). Similar changes were observed when serum IGFBP-1 was quantitated by immunoblotting. The effects of GH could not be explained by secondary hyperinsulinism, since no significant increase in insulin levels was observed in GH-treated rats. From these observations we conclude the enhanced expression of IGFBP-1 in the food-deprived rat may be a consequence of GH deficiency rather than insulin deficiency.

Transcriptional regulation of rat insulin-like growth factor-binding protein-1 expression by growth hormone

The low mol wt insulin-like growth factor-binding protein (IGFBP-1) originally isolated from amniotic fluid has been considered to be GH independent. In this report we have examined the effect of GH on hepatic IGFBP-1 expression in the hypophysectomized rat. Using a rat IGFBP-1 cDNA probe we now demonstrated that hepatic IGFBP-1 expression is up-regulated in the GH-deficient rat. In addition, using ligand blotting, an increase in the abundance of a 30-kDa [125I]IGF-I-BP was detected in both hepatic extracts and serum from hypophysectomized rats. After a single ip injection of GH, the IGFBP-1 transcription rate was reduced within 30 min to the levels seen in the sham-operated control rats. Similarly, hepatic IGFBP-1 mRNA abundance was reduced after both acute GH injection and chronic GH treatment for 8 days. These data demonstrate that IGFBP-1 expression is inversely regulated by GH.

Identification and characterization of a rat decidual insulin-like growth factor-binding protein complementary DNA

A partial cDNA which encodes the rat homolog of human placental protein-12, the low mol wt insulin-like growth factor-binding protein (IGFBP-1), has been isolated from a rat decidual cDNA library using low stringency hybridization with a human IGFBP-1 cDNA probe. The incomplete cDNA obtained from this library was used to screen a rat liver cDNA library from which a full-length cDNA was obtained. The predicted amino acid sequence of rat IGFBP-1 showed 66%, 29%, and 34% sequence identity with the human IGFBP-1, the human GH-dependent binding protein IGFBP-3, and rat IGFBP-2, the BP secreted by buffalo rat liver cells, respectively. The rat IGFBP-1 cDNA hybridized with a 1.6-kilobase transcript which was easily detected in uterine RNA from the pseudopregnant rat and RNA from the liver and kidney of adult rats. A low level of expression was apparent in the brain and the diestrous uterus. Of the tissues examined the order of abundance of IGFBP-1 mRNA was deciduoma tissue greater than or equal to liver much greater than kidney much greater than uterus greater than brain. The 1.6-kb mRNA was more abundant in RNA from neonatal rat liver than in that from maternal liver, but was not detected in total RNA (50 micrograms) from other neonatal rat tissues (kidney, lung, brain, and heart). Under stringent conditions, rat IGFBP-1 did not hybridize with RNA from the BRL-3A rat liver cell line. In food-deprived rats, hepatic IGFBP-1 mRNA was increased 10.0 +/- 2.2-fold compared to that in control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Further characterization of drug-sensitivity and cross-resistance profiles of cloned cell lines of Adriamycin-sensitive and -resistant P388 leukemia

The drug-sensitivity and cross-resistance profiles of cloned cell lines of Adriamycin-sensitive and -resistant P388 murine leukemia have been further characterized. A range of drug sensitivity that was more than 50,000-fold was observed for Adriamycin-sensitive cells; the most potent cytotoxic agent was the Adriamycin analog, 3'-(3-cyano-4-morpholinyl)-3'-deamino adriamycin, and the least active compound was vinblastine. Adriamycin-resistant cells, which express the multidrug resistance phenotype, were cross-resistant to the DNA topoisomerase II interactive drugs: actinomycin D, daunorubicin, mitoxantrone, etoposide, and 4'-(9-acridinyl-amino)methanesulfon-m-anisidide, to the vinca alkaloids: vincristine and vinblastine, and to colchicine but not to the Adriamycin analog, 3'-(3-cyano-4-morpholinyl)-3'-deamino adriamycin or the alkylating agent, melphalan. These findings are consistent with other studies suggesting that 3'-(3-cyano-4-morpholinyl)-3'-deamino adriamycin acts as an alkylating agent. Studies with DNA topoisomerase II interactive agents, including mitoxantrone, the DNA intercalator, and etoposide, the epipodophyllotoxin, showed that, as with Adriamycin, cytotoxicity correlated closely with the formation of DNA double-strand breaks.

Multifactorial resistance to adriamycin: relationship of DNA repair, glutathione transferase activity, drug efflux, and P-glycoprotein in cloned cell lines of adriamycin-sensitive and -resistant P388 leukemia

Cloned lines of Adriamycin (ADR)-sensitive and -resistant P388 leukemia have been established, including P388/ADR/3 and P388/ADR/7 that are 5- and 10-fold more resistant than the cloned sensitive cell line P388/4 (Cancer Res., 46: 2978, 1986). A time course of ADR-induced DNA double-strand breaks revealed that in sensitive P388/4 cells, evidence of DNA repair was noted 4 h after removal of drug, whereas in resistant clone 3 and 7 cells repair was observed 1 h after drug removal. The earlier onset of DNA repair was statistically significant (p = 0.0154 for clone 3 cells, and p = 0.0009 for clone 7 cells). By contrast, once the repair process was initiated, the rate of repair was similar for all three cell lines. The level of glutathione transferase activity was determined in whole cell extracts. Enzyme activity (mean +/- SE) in sensitive cells was 9.49 +/- 1.00 nmol/min/mg protein, that in resistant clone 3 cells was 13.36 +/- 1.03 nmol/min/mg, and that in clone 7 cells was 13.96 +/- 1.44 nmol/min/mg; the 1.44-fold increase in enzyme activity in resistant cells was statistically significant (p = 0.01). Further evidence of induction of glutathione transferase was provided by Northern blot analysis using a 32P-labeled cDNA for an anionic glutathione transferase, which demonstrated approximately a twofold increase in mRNA in resistant clone 7 cells. Western blot analysis with a polyvalent antibody against anionic glutathione transferase also revealed a proportionate increase in gene product in resistant cells. Dose-survival studies showed that ADR-resistant cells were cross-resistant to actinomycin D, daunorubicin, mitoxantrone, colchicine, and etoposide, but not to the alkylating agent melphalan; this finding provided evidence that these cells are multidrug resistant. Using a cDNA probe for P-glycoprotein, a phenotypic marker for multidrug resistance, Northern blot analysis showed an increase in the steady state level of mRNA of approximately twofold in resistant clone 3 and 7 cells. Southern analysis with the same cDNA probe showed no evidence of gene amplification or rearrangement. Western blot analysis with monoclonal C219 antibody demonstrated a distinct increase in P-glycoprotein in resistant cells. Efflux of Adriamycin as measured by the efflux rate constant was identical in all three cell lines. Furthermore, the metabolic inhibitors azide and dinitrophenol did not augment drug uptake in either sensitive or resistant cells. These findings suggest that despite the increase in P-glycoprotein, an active extrusion pump was not operational in these cells.(ABSTRACT TRUNCATED AT 400 WORDS)