Mouse MOV10L1 associates with Piwi proteins and is an essential component of the Piwi-interacting RNA (piRNA) pathway

Piwi-interacting RNAs (piRNAs) are essential for silencing of transposable elements in the germline, but their biogenesis is poorly understood. Here we demonstrate that MOV10L1, a germ cell–specific putative RNA helicase, is associated with Piwi proteins. Genetic disruption of the MOV10L1 RNA helicase domain in mice renders both MILI and MIWI2 devoid of piRNAs. Absence of a functional piRNA pathway in Mov10l1 mutant testes causes loss of DNA methylation and subsequent derepression of retrotransposons in germ cells. The Mov10l1 mutant males are sterile owing to complete meiotic arrest. This mouse mutant expresses Piwi proteins but lacks piRNAs, suggesting that MOV10L1 is required for piRNA biogenesis and/or loading to Piwi proteins.     

Pioglitazone administration decreases cardiovascular disease risk factors in insulin-resistant smokers

Insulin sensitivity varies in cigarette smokers, and there is evidence that cardiovascular disease (CVD) risk is greatest in those smokers who are also insulin resistant. To extend these observations, we sought to (1) compare CVD risk factors in smokers who do not plan to stop smoking, divided into insulin-resistant (IR) and insulin-sensitive (IS) subgroups, and (2) evaluate the ability of drug-induced changes in insulin sensitivity to decrease CVD risk. Thirty-six cigarette smokers were divided into IR (n = 19) and IS (n = 17) subgroups by determining their steady-state plasma glucose (SSPG) concentrations during the insulin suppression test (the higher the SSPG, the more insulin resistant the individual). In addition, baseline measurements were made of fasting lipid and lipoprotein concentrations; inflammatory markers; and daylong glucose, insulin, and free fatty acid responses to test meals. All subjects were treated with pioglitazone for 12 weeks, after which all baseline measurements were repeated. Baseline triglyceride and high-density lipoprotein cholesterol concentrations were significantly different in IR as compared with IS smokers (P < .05) both before and after adjustment for differences in sex and body mass index. After pioglitazone treatment, SSPG concentration significantly fell in the IR smokers (P < .001), associated with a significant improvement in the atherogenic lipoprotein profile seen at baseline (P ≤ .03) and a decrease in soluble intercellular adhesion molecule 1 and C-reactive protein concentrations (P = .01 and .02, respectively), whereas the IS smokers only had a significant increase in high-density lipoprotein cholesterol (P = .004) and a decrease in soluble intercellular adhesion molecule 1 (P = .02) and CRP (P = .07) levels. In conclusion, cigarette smokers have profound differences in CVD risk factors related to their degree of insulin sensitivity. It is suggested that, in addition to smoking cessation efforts, attention should be given to identifying the subgroup of smokers most at risk for CVD, but unwilling or unable to stop smoking, and to initiating appropriate therapeutic interventions to decrease CVD in this high-risk group.     

Safety of subcutaneous versus intravenous tocilizumab in combination with traditional disease-modifying antirheumatic drugs in patients with rheumatoid arthritis

Introduction: Tocilizumab (TCZ), a humanized anti-IL-6 receptor (IL-6R) monoclonal antibody, has demonstrated efficacy and tolerability in several large randomized, controlled trials for the treatment of rheumatoid arthritis (RA).

Areas covered: This article compares the safety profile of the newer, subcutaneous (SC) formulation of TCZ with the original intravenous (IV) formulation, in combination with traditional disease-modifying antirheumatic drugs (DMARDs) in patients with RA. Several pivotal clinical trials are included, highlighting data from: i) trials of TCZ-IV; ii) trials of TCZ-SC; and iii) trials comparing IV to SC TCZ. TCZ use in pediatric populations is beyond the scope of this review.

Expert opinion: The efficacy and safety of TCZ-IV in the treatment of RA has been demonstrated in multiple clinical trials, both as monotherapy and in combination with traditional DMARDs. The data for TCZ-SC is similar, albeit with a higher frequency of injection site reactions (ISRs). With careful patient selection, the benefit: risk ratio is favorable, offering patients a rapid and sustained reduction in disease activity, improved function and reduced structural damage. Given that most patients prefer SC to IV medication, TCZ-SC will likely become a mainstay, along with other biologic agents, for the treatment of RA patients who have failed traditional non-biologic DMARDs.     

High carbohydrate diets, triglyceride-rich lipoproteins, and coronary heart disease risk

In this study we compared the effects of variations in dietary fat and carbohydrate (CHO) content on concentrations of triglyceride-rich lipoproteins in 8, healthy, nondiabetic volunteers. The diets contained, as a percentage of total calories, either 60% CHO, 25% fat, and 15% protein, or 40% CHO, 45% fat, and 15% protein. They were consumed in random order for 2 weeks, with a 2-week washout period in between. Measurements were obtained at the end of each dietary period of plasma triglyceride, cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, remnant lipoprotein (RLP) cholesterol, and RLP triglyceride concentrations, both after an overnight fast and throughout an 8-hour period (8 A.M. to 4 P.M.) in response to breakfast and lunch. The 60% CHO diet resulted in higher (mean +/- SEM) fasting plasma triglycerides (206 +/- 50 vs 113 +/- 19 mg/dl, p = 0.03), RLP cholesterol (15 +/- 6 vs 6 +/- 1 mg/dl, p = 0.005), RLP triglyceride (56 +/- 25 vs 16 +/- 3 mg/dl, p = 0.003), and lower HDL cholesterol (39 +/- 3 vs 44 +/- 3 mg/dl, p = 0.003) concentrations, without any change in LDL cholesterol concentration. Furthermore, the changes in plasma triglyceride, RLP cholesterol, and RLP triglyceride persisted throughout the day in response to breakfast and lunch. These results indicate that the effects of lowfat diets on lipoprotein metabolism are not limited to higher fasting plasma triglyceride and lower HDL cholesterol concentrations, but also include a persistent elevation in RLPs. Given the atherogenic potential of these changes in lipoprotein metabolism, it seems appropriate to question the wisdom of recommending that all Americans should replace dietary saturated fat with CHO.     

Amidolytic assay of human factor XI in plasma: comparison with a coagulant assay and a new rapid radioimmunoassay

The traditional coagulant assay for plasma factor XI suffers from a relatively high coefficient of variation, the need for rare congenitally deficient plasma, and a poor correlation between precision and sensitivity. We have developed a simple functional amidolytic assay for factor XI in plasma using the chromogenic substrate PyrGlu-Pro-Arg- p-nitroanilide (S-2366). After inactivation of alpha 1-antitrypsin, CI inhibitor, and other plasma protease inhibitors with CHCI3, plasma was incubated with kaolin, in the absence of added calcium, which limited the enzymes formed to those dependent on contact activation. Soybean trypsin inhibitor was used to minimize the action of kallikrein on the substrate. Once the reaction was complete, corn trypsin inhibitor was used to inactive factor XIIa, the enzyme generated by exposure of plasma to negatively charged surfaces, which had activated the factor XI. The assay is highly specific for factor XI, since plasma totally deficient in that zymogen yielded only 1%-3% of the enzymatic activity in normal plasma under identical conditions. The requirements for complete conversion of factor XI to XIa in plasma within 60 min were, respectively, factor XII, 0.6 U/ml, and high molecular weight kininogen, 0.2 U/ml. Prekallikrein was not an absolute requirement for complete activation but did accelerate the reaction. The intraassay coefficient of variation was 3.4%, and the mean of 35 normal plasmas was 1.00 U +/- 0.24 SD. In addition, a new rapid radioimmunoassay was devised using staphylococcal protein A as the precipitating agent for a complex of factor XI antigen with monospecific rabbit antibody. The mean was 1.01 U +/- 0.30 SD. The correlation coefficients for amidolytic versus coagulant and amidolytic versus radioimmunoassay were r = 0.95 for the former and 0.96 for the latter. Thus, a simple, accurate amidolytic assay and a radioimmunoassay have been devised for measuring factor XI in plasma that correlate well with the coagulant activity of factor XI, as determined in our laboratory.     

Positive allosteric modulation of the mu-opioid receptor produces analgesia with reduced side effects

Positive allosteric modulators (PAMs) of the mu-opioid receptor (MOR) have been hypothesized as potentially safer analgesics than traditional opioid drugs. This is based on the idea that PAMs will promote the action of endogenous opioid peptides while preserving their temporal and spatial release patterns and so have an improved therapeutic index. However, this hypothesis has never been tested. Here, we show that a mu-PAM, BMS-986122, enhances the ability of the endogenous opioid Methionine-enkephalin (Met-Enk) to stimulate G protein activity in mouse brain homogenates without activity on its own and to enhance G protein activation to a greater extent than β-arrestin recruitment in Chinese hamster ovary (CHO) cells expressing human mu-opioid receptors. Moreover, BMS-986122 increases the potency of Met-Enk to inhibit GABA release in the periaqueductal gray, an important site for antinociception. We describe in vivo experiments demonstrating that the mu-PAM produces antinociception in mouse models of acute noxious heat pain as well as inflammatory pain. These effects are blocked by MOR antagonists and are consistent with the hypothesis that in vivo mu-PAMs enhance the activity of endogenous opioid peptides. Because BMS-986122 does not bind to the orthosteric site and has no inherent agonist action at endogenously expressed levels of MOR, it produces a reduced level of morphine-like side effects of constipation, reward as measured by conditioned place preference, and respiratory depression. These data provide a rationale for the further exploration of the action and safety of mu-PAMs as an innovative approach to pain management.

Mu-opioid receptor (MOR) agonists are the most effective treatments for moderate to severe acute and chronic pain, yet their use is limited by serious side effects, including constipation, respiratory depression, and physical and psychological dependence. These side effects are on-target effects (MOR-mediated) and result from the wide distribution of MORs across the central nervous system (CNS) (1, 2). Safer pain therapies are desperately needed. However, because of the efficacy of MOR agonists in blocking pain, this receptor continues to be a primary target for the discovery of novel pain therapies. Unfortunately, most drug discovery programs involve designing compounds that bind to the orthosteric site on MOR—the site that binds endogenous opioid peptides as well as exogenous opioids. Not surprisingly, these newer drugs tend to exhibit qualitatively similar side effect profiles to traditional opioid analgesics.As an alternative, we have discovered small molecule, positive allosteric modulators of MOR [mu-PAMs (3)], including BMS-986122 (SI Appendix, Fig. S1). Such compounds interact with a site on MOR that is spatially distinct from the orthosteric site (3–7). Across a variety of in vitro assays, mu-PAMs increase the affinity and/or potency of orthosteric agonists at MOR, including exogenous MOR agonists as well as the endogenous opioid peptides Leucine- and Methionine-enkephalin, endomorphin-1, and β-endorphin (3, 8).These in vitro studies have led to development of a so-far untested hypothesis that in vivo, mu-PAMs will promote the activity of endogenous opioid peptides released during pain (9–11). If this hypothesis is correct, mu-PAMs could replace traditional opioids by boosting the body’s own natural response to pain to provide clinically meaningful analgesia. In support of this concept, so called “enkephalinase inhibitors” that prolong the lifetime of endogenous opioid peptides are effective in the management of pain in preclinical and clinical studies (12–14), although such compounds are not selective for opioid peptides. Since mu-PAMs do not alter peptide release or metabolism, they should be more selective than enkephalinase inhibitors and also preserve the natural spatial and temporal release of the peptides in vivo following injury and/or during pain. To test this hypothesis, we examined the antinociceptive effects of BMS-986122 in mouse models of acute and inflammatory pain using measures of pain-evoked and pain-depressed behaviors as well as opioid side effects and the potential role of endogenous opioid peptides in these responses.     

Relationship between pain and opioid analgesics on the development of delirium following hip fracture

BACKGROUND: Delirium and pain are common following hip fracture. Untreated pain has been shown to increase the risk of delirium in older adults undergoing elective surgery. This study was performed to examine the relationship among pain, analgesics, and other factors on delirium in hip fracture patients. METHODS: We conducted a prospective cohort study at four New York hospitals that enrolled 541 patients with hip fracture and without delirium. Delirium was identified prospectively by patient interview supplemented by medical record review. Multiple logistic regression was used to identify risk factors. RESULTS: Eighty-seven of 541 patients (16%) became delirious. Among all subjects, risk factors for delirium were cognitive impairment (relative risk, or RR, 3.6; 95% confidence interval, or CI, 1.8-7.2), abnormal blood pressure (RR 2.3, 95% CI 1.2-4.7), and heart failure (RR 2.9, 95% CI 1.6-5.3). Patients who received less than 10 mg of parenteral morphine sulfate equivalents per day were more likely to develop delirium than patients who received more analgesia (RR 5.4, 95% CI 2.4-12.3). Patients who received meperidine were at increased risk of developing delirium as compared with patients who received other opioid analgesics (RR 2.4, 95% CI 1.3-4.5). In cognitively intact patients, severe pain significantly increased the risk of delirium (RR 9.0, 95% CI 1.8-45.2). CONCLUSIONS: Using admission data, clinicians can identify patients at high risk for delirium following hip fracture. Avoiding opioids or using very low doses of opioids increased the risk of delirium. Cognitively intact patients with undertreated pain were nine times more likely to develop delirium than patients whose pain was adequately treated. Undertreated pain and inadequate analgesia appear to be risk factors for delirium in frail older adults.     

Impact of ST-segment resolution after primary angioplasty on outcomes after myocardial infarction in elderly patients: an analysis from the CADILLAC trial

Background

Age is a strong independent predictor of outcomes after primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI). Whether lower rates of reperfusion success contribute to the poor prognosis in elderly patients is unknown.

Methods

A formal ST-segment analysis substudy was performed in 695 patients undergoing primary PCI for AMI in the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial. Reperfusion success (determined by the magnitude of ST-segment elevation resolution [STR] after PCI) was evaluated in 4 age groups: <50 years (n = 163), ≥50 to <60 years (n = 187), ≥60 to <70 years (n = 194), and ≥70 years (n = 151).

Results

There were no differences in the age groups for angiographic procedural success >91% in all, P = .6), postprocedural Thrombolysis in Myocardial Infarction grade 3 flow >94%, P = .8), and the proportions of patients with complete, partial, or absent STR (P >.8). However, rates of 30-day mortality (0.6%, 1.1%, 3.6%, 6.0%, respectively) and major adverse cardiac events (MACE; 2.5%, 4.8%, 6.2% 9.3%, respectively) increased with age. Rates of mortality and MACE were also inversely related to the magnitude of STR. Absent STR (hazard ratio, 3.00; 95% CI, 1.37-6.58; P = .006) and age (hazard ratio, 1.34; 95% CI, 1.01-1.77; P = .04) were independent predictors of 30-day MACE by using multivariable modeling.

Conclusions

Lack of effective myocardial reperfusion is not a contributory mechanism responsible for the high morbidity and mortality rates observed in elderly patients. Nevertheless, advanced age and absent STR are both independent predictors of adverse outcomes after primary PCI, emphasizing the importance of successful reperfusion in the elderly population.