Surgeons guideline recommends tramadol for patients with knee osteoarthritis, and an American College of Rheumatology guideline conditionally recommends tramadol as first-line therapy for patients with knee osteoarthritis, along with nonsteroidal anti-inflammatory drugs.OBJECTIVE To examine the association of tramadol prescription with all-cause mortality among patients with osteoarthritis. DESIGN, SETTING, AND PARTICIPANTS Sequential, propensity score-matched cohort study at a general practice in the United Kingdom. Individuals aged at least 50 years with a diagnosis of osteoarthritis in the Health Improvement Network database from January 2000 to December 2015, with follow-up to December 2016. EXPOSURES Initial prescription of tramadol (n = 44 451), naproxen (n = 12 397), diclofenac (n = 6512), celecoxib (n = 5674), etoricoxib (n = 2946), or codeine (n = 16 922). MAIN OUTCOMES AND MEASURES All-cause mortality within 1 year after initial tramadol prescription, compared with 5 other pain relief medications. RESULTS After propensity score matching, 88 902 patients were included (mean [SD] age, 70.1 [9.5] years; 61.2% were women). During the 1-year follow-up, 278 deaths (23.5/1000 person-years) occurred in the tramadol cohort and 164 (13.8/1000 person-years) occurred in the naproxen cohort (rate difference, 9.7 deaths/1000 person-years [95% CI, 6.3-13.2]; hazard ratio [HR], 1.71 [95% CI, 1.41-2.07]), and mortality was higher for tramadol compared with diclofenac (36.2/1000 vs 19.2/1000 person-years; HR, 1.88 [95% CI, 1.51-2.35]).Tramadol was also associated with a higher all-cause mortality rate compared with celecoxib (31.2/1000 vs 18.4/1000 person-years; HR, 1.70 [95% CI, 1.33-2.17]) and etoricoxib (25.7/1000 vs 12.8/1000 person-years; HR, 2.04 [95% CI, 1.37-3.03]). No statistically significant difference in all-cause mortality was observed between tramadol and codeine (32.2/1000 vs 34.6/1000 person-years; HR, 0.94 [95% CI, 0.83-1.05]).CONCLUSIONS AND RELEVANCE Among patients aged 50 years and older with osteoarthritis, initial prescription of tramadol was associated with a significantly higher rate of mortality over 1 year of follow-up compared with commonly prescribed nonsteroidal anti-inflammatory drugs, but not compared with codeine. However, these findings may be susceptible to confounding by indication, and further research is needed to determine if this association is causal.

In the present study, we produced single point mutations in the ATP binding site of hamster BiP, isolated recombinant proteins, and characterized them in terms of their affinity for ATP and ADP, their ability to undergo a conformational change upon nucleotide binding, and their rate of ATP hydrolysis. These analyses allowed us to classify the mutants into three groups: ATP hydrolysis (T229G), ATP binding (G226D, G227D), and ATP-induced conformation (T37G) mutants, and to test the role of these activities in the in vitro ATP-mediated release of proteins from BiP. All three classes of mutants were still able to bind peptide demonstrating that nucleotide is not involved in this function. Addition of ATP to either wild-type BiP or the T229G mutant caused the in vitro release of bound peptide, confirming that ATP hydrolysis is not required for protein release. ATP did not dissociate G226D, G227D, or T37G mutant BiP-peptide complexes, suggesting that ATP binding to BiP is not sufficient for the release of bound peptides, but that an ATP-induced conformational change in BiP is necessary. The identification of BiP mutants that are defective in each of these steps of ATP hydrolysis will allow the in vivo dissection of the role of nucleotide in BiP's activity.The heat shock protein 70 (HSP70) 1 family of chaperones are components of the cellular machinery for folding, assembly, and degradation of proteins (1). These proteins are thought to undergo cycles of nucleotide-mediated binding and release to unfolded polypeptides. The binding of peptides to HSP70 proteins stimulates their ATPase activity (2), and bound peptides or proteins are released with ATP but not with non-hydrolyzable analogues (2-5). These observations have led to the conclusion that ATP hydrolysis is required for HSP70 activity and that there are functional interactions between the ATP binding and protein binding domains. All HSP70 proteins bind ATP tightly but the ATP hydrolysis rates of purified proteins are so low under physiological conditions, that other co-factors may be required to enhance the rate of ATP hydrolysis. In bacteria two co-factors, dnaJ and grpE, have been identified that together increase the ATPase activity of dnaK (bacterial HSP70 homologue) up to 50-fold (6). Although dnaJ homologues have been identified in several organelles in various organisms (7), the only eukaryotic grpE homologues found thus far are mitrochondrial (8, 9). Alternatively, it is possible that ATP binding rather than ATP hydrolysis is essential for HSP70 function. In support of this hypothesis, investigators have recently demonstrated that peptides are released from both dnaK and hsc70 (mammalian cytosolic homologue) after ATP binding but before ATP hydrolysis occurs (10). Thus, it is presently unclear whether ATP binding, ATP hydrolysis, or both are important for HSP70 function in vivo.The ATP binding domain of all HSP70 members resides within a highly conserved NH 2 -terminal 44-kDa fragment that can be generated by proteolysis (11,12). The structure of the ATP ...

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Objective: A recent randomized clinical trial reported that repeated intra-articular corticosteroids (IACs) were associated with a greater cartilage loss. This study aimed to examine the relation of IACs to knee radiographic osteoarthritis (ROA) progression in a real-world setting. Design: A cohort that initiated IACs and a comparison cohort without IACs from participants with mild to moderate knee ROA in the Osteoarthritis Initiative (OAI) were assembled (from 0-month to 48-month). Two measures of knee ROA progression were assessed during the follow-up period: (1) an increase in Kellgren and Lawrence (KL) grade by 1 grade or having a knee replacement (i.e., KL grade worsening); and (2) a decrease in joint space width (JSW) by 0.7 mm or having a knee replacement (i.e., JSW worsening). The associations of IACs initiation using a propensity-score matched cohort study and continuous IACs using marginal structural models with the risk of knee ROA progression were examined. Results: Among 684 propensity-score matched participants at baseline (148 IACs initiators, 536 comparators), 65 knees (21.7/100 person-years) in the IACs initiation cohort and 90 knees (7.1/100 personyears) in the comparison cohort experienced KL worsening. The hazard ratios (HRs) of KL worsening from IACs initiation and continuous IACs were 3.02 (95% confidence interval [CI], 2.19e4.16) and 4.67 (95% CI, 2.92e7.47), respectively. The corresponding HRs of JSW worsening were 2.93 (95% CI, 2.13e4.02) and 3.26 (95% CI, 1.78e5.96), respectively. All HRs for continuous use of IACs were further away from the null. Conclusions: IACs, especially continuous IACs, may be associated with an increased risk of knee ROA progression.

BiP possesses ATP binding/hydrolysis activities that are thought to be essential for its ability to chaperone protein folding and assembly in the endoplasmic reticulum (ER). We have produced a series of point mutations in a hamster BiP clone that inhibit ATPase activity and have generated a species-specific anti-BiP antibody to monitor the effects of mutant hamster BiP expression in COS monkey cells. The enzymatic inactivation of BiP did not interfere with its ability to bind to Ig heavy chains in vivo but did inhibit ATP-mediated release of heavy chains in vitro. Immunofluorescence staining and electron microscopy revealed vesiculation of the ER membranes in COS cells expressing BiP ATPase mutants. ER disruption was not observed when a "44K" fragment of BiP that did not include the protein binding domain was similarly mutated but was observed when the protein binding region of BiP was expressed without an ATP binding domain. This suggests that BiP binding to target proteins as an inactive chaperone is responsible for the ER disruption. This is the first report on the in vivo expression of mammalian BiP mutants and is demonstration that in vitro-identified ATPase mutants behave as dominant negative mutants when expressed in vivo.

BackgroundThe association between serum selenium levels and type 2 diabetes mellitus (T2DM) is controversial. We performed a systematic review and non-linear dose–response meta-analysis of observational studies to investigate the association in the present study.MethodsA comprehensive literature search was conducted using MEDLINE and EMBASE databases. A pooled odds ratio (OR) and related 95 % confidence interval (95 % CI) for T2DM between the highest and lowest serum selenium categories, and a non-linear dose–response relationship between selenium and T2DM were estimated.ResultsA total of five studies (of 13,460 participants) were identified as meeting the inclusion criteria. The pooled OR indicated that there was a significantly higher prevalence of T2DM in the highest category of blood selenium compared with the lowest (OR = 1.63, 95 % CI: 1.04–2.56, P = 0.033). Moreover, a significant non-linear dose–response relationship was observed between serum selenium levels and T2DM (P < 0.001). Serum selenium levels were positively associated with T2DM in populations with relatively low serum selenium levels (<97.5 μg/l) and those with high serum selenium levels (>132.5 μg/l).ConclusionsThe positive association between serum selenium levels and T2DM existed in populations with relatively low levels and high levels of serum selenium, indicating a likely U-shaped non-linear dose–response relationship between serum selenium and T2DM.Electronic supplementary materialThe online version of this article (doi:10.1186/s12937-016-0169-6) contains supplementary material, which is available to authorized users.

BackgroundSelenium is an important trace element for human health. Although numerous epidemiological and interventional studies have examined the association between selenium and diabetes, their findings have been inconclusive. Moreover, no research has specifically focused on the association between dietary selenium and diabetes in the Asian population. The objective of this study was to evaluate the relationship between dietary selenium and diabetes in middle-aged and elderly Chinese adults.MethodsA cross-sectional study including 5,423 subjects was carried out. The basic characteristics, biochemical test results, and dietary intake were collected from each subject for analysis. The adjusted odds ratio (OR) and the corresponding 95% confidence interval (CI) were used to determine the relationship between dietary selenium intake and diabetes through logistic regression.ResultsThe prevalence of diabetes in the study population was 9.7%, and the average level of dietary selenium intake was 43.51 μg/day. The multivariate adjusted OR was 1.52 (95% CI: 1.01 to 2.28, P = 0.04) for the highest quartile of dietary selenium intake in comparison with the lowest quartile. There was a significant positive association between dietary selenium intake and diabetes (P for trend = 0.03).ConclusionThere was a significant positive correlation between dietary selenium intake and the prevalence of diabetes.

HSP70 family proteins bind ATP and hydrolyze it, but the precise role of these activities in their in vivo chaperoning function has not been determined. In this report, we characterized wild-type hamster BiP isolated from bacteria in terms of its ATP binding and ATPase activities. Recombinant BiP behaved essentially the same as endogenous BiP in terms of oligomeric status, protease digestion patterns, and ATPase properties. By engineering a Factor Xa cleavable site following the His tag which was used for affinity purification, we demonstrated that the six histidines had no effect on either the structural or ATPase properties of recombinant BiP. We also found that bacteria-synthesized BiP had a tightly bound ADP that was resistant to dialysis. Removal of the bound nucleotide allowed us to directly measure the binding affinity of ATP and ADP to BiP (K d of 0.2 M for ATP and 0.29 M for ADP) by equilibrium dialysis. Careful characterization of wild-type BiP will allow us to use this system to characterize BiP ATP binding site mutants that can be used to probe the role of ATP binding and ATPase activity in BiP functions.The heat shock protein 70 (HSP70) 1 family is comprised of a highly conserved class of molecular chaperones. Members of this family exist in all species from Escherichia coli to human and in all the organelles of eukaryotic cells (1, 2). Most of these proteins are constitutively expressed and are further induced under conditions of stress like heat shock or other physiological insults to the cells (1). Immunoglobulin heavy chain binding protein (BiP) is the eukaryotic endoplasmic reticulum (ER) member of the HSP70 family, and is one of the major resident ER proteins. BiP is proposed to play a role in protein folding, subunit assembly, and subsequent transport of proteins from the ER (2). BiP associates transiently with a variety of nascent secretory proteins (3-7) and more stably with malfolded or unassembled proteins whose transport from the ER is blocked (3-5, 8, 9). However, the extent of BiP's involvement in these processes is not clearly understood.All HSP70 family members possess a highly conserved NH 2 -terminal ATP binding domain and a more variable COOHterminal protein binding domain (10, 11). The three-dimensional structure of the NH 2 -terminal 44-kDa proteolytic fragment of bovine brain hsc70, a cytoplasmic HSP70, has been determined. This fragment contains the ATP binding site, and its structure is very similar to that of two other adenine nucleotide binding proteins: actin and hexokinase, even though their amino acid sequence homology is not high (12, 13). Studies on both recombinant and purified bovine hsc70 revealed that hsc70 binds ATP and ADP with K d values in the order of 10 Ϫ5-10 Ϫ8 M (14 -18). Although all family members presumably have a similar nucleotide binding structure, direct binding studies have not been done on BiP or other HSP70 members. The HSP70s also have a rather weak intrinsic ATPase activity. For BiP, the reported turnover numbers for ATPase activity range from 0...