The extra domain A of fibronectin activates Toll-like receptor 4

Cellular fibronectin, which contains an alternatively spliced exon encoding type III repeat extra domain A (EDA), is produced in response to tissue injury. Fragments of fibronectin have been implicated in physiological and pathological processes, especially tissue remodeling associated with inflammation. Because EDA-containing fibronectin fragments produce cellular responses similar to those provoked by bacterial lipopolysaccharide (LPS), we examined the ability of recombinant EDA to activate Toll-like receptor 4 (TLR4), the signaling receptor stimulated by LPS. We found that recombinant EDA, but not other recombinant fibronectin domains, activates human TLR4 expressed in a cell type (HEK 293 cells) that normally lacks this Toll-like receptor. EDA stimulation of TLR4 was dependent upon co-expression of MD-2, a TLR4 accessory protein. Unlike LPS, the activity of EDA was heat-sensitive and persisted in the presence of the LPS-binding antibiotic polymyxin B and a potent LPS antagonist, E5564, which completely suppressed LPS activation of TLR4. These observations provided a mechanism by which EDA-containing fibronectin fragments promote expression of genes involved in the inflammatory response.

Psychological Outcomes Associated with Stay-at-Home Orders and the Perceived Impact of COVID-19 on Daily Life

The COVID-19 pandemic has resulted in the widespread implementation of extraordinary physical distancing interventions (e.g., stay-at-home orders) to slow the spread of the virus. Although vital, these interventions may be socially and economically disruptive, contributing to adverse psychological outcomes. This study examined relations of both stay-at-home orders and the perceived impact of COVID-19 on daily life to psychological outcomes (depression, health anxiety, financial worry, social support, and loneliness) in a nationwide U.S. community adult sample (N = 500; 47% women, mean age = 40). Participants completed questionnaires assessing psychological outcomes, stay-at-home order status, and COVID-19's impact on their daily life. Being under a stay-at-home order was associated with greater health anxiety, financial worry, and loneliness. Moreover, the perceived impact of COVID-19 on daily life was positively associated with health anxiety, financial worry, and social support, but negatively associated with loneliness. Findings highlight the importance of social connection to mitigate negative psychological consequences of the COVID-19 pandemic.

Human immunodeficiency virus type 1 mutants resistant to nonnucleoside inhibitors of reverse transcriptase arise in tissue culture

We have recently described a nonnucleoside compound that specifically inhibits the reverse transcriptase of human immunodeficiency virus type 1 (HIV-1), the causative agent of AIDS. This compound, nevirapine (BI-RG-587), interacts with highly conserved tyrosine residues at positions 181 and 188 in the reverse transcriptase to inhibit the recombinant enzyme and virus replication in cell culture with 50% inhibitory concentrations in the 40 nM range. HIV-1 variants resistant to nevirapine emerged with passage in cell culture in the presence of drug. This resistant phenotype was stable with continued passage in the absence of drug. These mutants had a substitution of cysteine for the tyrosine at position 181. Introduction of this mutation into the recombinant enzyme increased the inhibitory concentration of nevirapine 100-fold. Substitution of cysteine for tyrosine at residue 181 into the wild-type viral genome conferred a similar reduction in susceptibility to nevirapine. Mutants were also resistant to a tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-one and -thione derivative and two 6-phenylthiouracil derivatives but retained their sensitivity to the other reverse transcriptase inhibitors, 3'-azido-3'-deoxythymidine and foscarnet.

Social and emotional loneliness: an examination of Weiss's typology of loneliness

This study examined Weiss' conceptualization of social and emotional loneliness. Using data from an extensive survey of undergraduate and graduate students at the University of Iowa, we measured social and emotional loneliness, students' affective and behavioral reactions to loneliness, students' social relationships, and their judgments of the degree to which their relationships supply the six social provisions described by Weiss. As expected, we found differences in the subjective experiences of social and emotional loneliness, although both forms of loneliness were also characterized by a common core of experiences. The results generally supported Weiss's ideas concerning the determinants of social and emotional loneliness. Predictions concerning the affective and behavioral consequences associated with each type of loneliness, however, were only partly supported, although the two forms of loneliness were associated with different affective reactions and coping behaviors. The implications of these findings for Weiss's typology of loneliness are discussed.

Crystal structure of bacteriophage T7 RNA polymerase at 3.3 A resolution

The crystal structure of T7 RNA polymerase reveals a molecule organized around a cleft that can accommodate a double-stranded DNA template. A portion (approximately 45%) of the molecule displays extensive structural homology to the polymerase domain of Klenow fragment and more limited homology to the human immunodeficiency virus HIV-1 reverse transcriptase. A comparison of the structures and sequences of these polymerases identifies structural elements that may be responsible for discriminating between ribonucleotide and deoxyribonucleotide substrates, and RNA and DNA templates. The relative locations of the catalytic site and a specific promoter recognition residue allow the orientation of the polymerase on the template to be defined.

The first structure of an aldehyde dehydrogenase reveals novel interactions between NAD and the Rossmann fold

The first structure of an aldehyde dehydrogenase (ALDH) is described at 2.6 A resolution. Each subunit of the dimeric enzyme contains an NAD-binding domain, a catalytic domain and a bridging domain. At the interface of these domains is a 15 A long funnel-shaped passage with a 6 x 12 A opening leading to a putative catalytic pocket. A new mode of NAD binding, which differs substantially from the classic beta-alpha-beta binding mode associated with the 'Rossmann fold', is observed which we term the beta-alpha,beta mode. Sequence comparisons of the class 3 ALDH with other ALDHs indicate a similar polypeptide fold, novel NAD-binding mode and catalytic site for this family. A mechanism for enzymatic specificity and activity is postulated.

Parenting stress in mothers of children with an intellectual disability: the effects of parental cognitions in relation to child characteristics and family support

BACKGROUND

Recent theories of stress and coping in parents of children with intellectual disabilities (ID) emphasize the importance of cognitive appraisals in influencing parents' levels of stress and their adaptations to difficulties presented by the children. This study investigated the relationships between parental cognitions, child characteristics, family support and parenting stress. The aspects of cognitions studied were: parenting self-esteem (including efficacy and satisfaction) and parental locus of control.

METHODS

The group studied consisted of 46 mothers of children with ID. The Vineland Adaptive Behavior Scales and Maladaptive Behavior Domain were administered by interview. Mothers also completed four questionnaires: the Family Support Scale, the Parenting Sense of Competence Scale, a shortened form of the Parental Locus of Control Scale and the Parenting Stress Index (Short Form).

RESULTS

Data were analysed using Pearson's correlation coefficients, partial correlations and a regression analysis. The results indicated that most of the variance in parenting stress was explained by parental locus of control, parenting satisfaction and child behaviour difficulties. Whilst there was also a strong correlation between family support and parenting stress, this was mediated by parental locus of control.

CONCLUSIONS

The results demonstrate the potential importance of parental cognitions in influencing parental stress levels. It is argued that these results have implications for clinical interventions for promoting parents' coping strategies in managing children with ID and behavioural difficulties.

Avoidable factors contributing to death after head injury

We reviewed 116 patients, known to have talked before dying after head injury, to discover factors which had contributed to death but which might have been avoided. All the patients were admitted to a neurosurgical unit and had a neuropathological post-mortem examination. One or more avoidable factors were identified in 86 patients (74%); an avoidable factor was judged certainly to have contributed to death in 63 patients (54%). The most common avoidable factor was delay in the treatment of an intracranial haematoma; others included poorly controlled epilepsy, meningitis, hypoxia, and hypotension. Changes in the management of patients with head injuries which reduce the incidence of avoidable factors should decrease mortality from this condition.

Development of short-term myocardial hibernation. Its limitation by the severity of ischemia and inotropic stimulation

BACKGROUND

Short-term hibernating myocardium is characterized by a decrease in contractile function in proportion to the reduced myocardial blood flow. Myocardial creatine phosphate content, initially decreased during the first minutes of ischemia, returns to near-control values, the ischemia-induced net lactate production is attenuated, and the myocardium remains viable despite ongoing hypoperfusion and contractile dysfunction. Hibernating myocardium after 85 minutes of ischemia maintains an inotropic reserve and responds to short-term intracoronary dobutamine infusion with increased work; however, this inotropic response is at the expense of metabolic recovery. We therefore hypothesized that the development of myocardial hibernation is a delicate process that is easily disturbed by unfavorable alterations in the oxygen-supply demand balance.

METHODS AND RESULTS

To study the impact of prolonged inotropic stimulation on the development of myocardial hibernation, the left anterior descending coronary artery was cannulated and hypoperfused at constant flow in 12 enflurane-anesthetized swine. The reduction of coronary inflow was followed by a reduction of regional myocardial work (sonomicrometry) from 248 +/- 59 mm Hg.mm to 73 +/- 35 mm Hg.mm (P < .05) at 5 minutes of ischemia. Dobutamine (2.5 +/- 1 micrograms/min) was then infused for an additional 85 minutes. Work was increased at 5 minutes of dobutamine to 139 +/- 34 mm Hg.mm (P < .05 versus 5 minutes of ischemia). However, this increase was only transient, and after 85 minutes of dobutamine, work was decreased below the initial ischemic value (42 +/- 34 mm Hg.mm). At 5 minutes of ischemia, creatine phosphate content was reduced from 8.80 +/- 1.97 to 6.21 +/- 3.87 mumol/g wet wt, and myocardial ATP content was decreased slightly from 4.75 +/- 0.92 to 4.12 +/- 1.29 mumol/g wet wt (both, P = NS). After 5 minutes of dobutamine, further reductions in creatine phosphate content to 3.11 +/- 0.76 mumol/g wet wt and in ATP to 3.14 +/- 0.81 mumol/g wet wt were observed (both, P < .05 versus control). During the remainder of the continuous dobutamine infusion, creatine phosphate content remained unchanged, whereas ATP further decreased significantly to 1.68 +/- 0.96 mumol/g wet wt. The beta-adrenoceptor density of the left anterior descending coronary artery-perfused myocardium was 36.5 +/- 5.8 fmol (-)-[125I]iodocyanopindolol/mg protein under control conditions, and this was unchanged during ischemia and the subsequent dobutamine infusion. Following 90 minutes of ischemia with 85 minutes of dobutamine and 2 hours of reperfusion, infarct size (triphenyl tetrazolium chloride staining) was 26.3 +/- 7.5% of the area at risk. With constant hypoperfusion, dobutamine redistributed blood flow away from the subendocardium (0.20 +/- 0.08 versus 0.11 +/- 0.04 mL.min-1.g-1) toward the subepicardium (0.45 +/- 0.13 versus 0.51 +/- 0.21 mL.min-1.g-1) as well as to the right ventricle (0.26 +/- 0.08 versus 0.32 +/- 0.09 mL.min-1.g-1). Therefore, in two other groups of six and five swine, the severity of ischemia was increased to achieve an 80% or a 90% reduction in regional function, respectively, and the importance of the severity of blood flow reduction per se for the development of myocardial infarction was studied. The infarct size in the animals undergoing 85 minutes of dobutamine (26.3 +/- 7.5%) was increased above the level expected from the blood flow reduction alone (6.3 +/- 6.4%, P < .01).

CONCLUSIONS

Both the increased severity of ischemia and the enhanced energy expenditure induced by dobutamine impair the development of myocardial short-term hibernation and precipitate myocardial infarction.

Long-term prognosis of mitral-valve prolapse

We examined the natural history of mitral-valve prolapse in 53 patients who had had a midsystolic click or late systolic murmur (or both) documented phonocardiographically a mean of 13.7 years earlier. Thirty-eight patients were alive without serious complications, and seven had died of unrelated causes. In two patients prolapse was implicated in the cause of death. Other complications were ventricular fibrillation in one patient and bacterial endocarditis in three. Progressive mitral regurgitation developed in five patients, requiring valve replacement in two. These complications occurred in a total of eight patients (15 per cent), and were significantly (P = 0.15) associated with a late systolic murmur rather than an isolated midsystolic click. Thus it appears that the diagnosis of mitral-valve prolapse should not be regarded as ominous; however, patients in whom this diagnosis is associated with a late systolic murmur should be followed carefully.

The 2.0 A structure of human ferrochelatase, the terminal enzyme of heme biosynthesis

Human ferrochelatase (E.C. 4.99.1.1) is a homodimeric (86 kDa) mitochondrial membrane-associated enzyme that catalyzes the insertion of ferrous iron into protoporphyrin to form heme. We have determined the 2.0 A structure from the single wavelength iron anomalous scattering signal. The enzyme contains two NO-sensitive and uniquely coordinated [2Fe-2S] clusters. Its membrane association is mediated in part by a 12-residue hydrophobic lip that also forms the entrance to the active site pocket. The positioning of highly conserved residues in the active site in conjunction with previous biochemical studies support a catalytic model that may have significance in explaining the enzymatic defects that lead to the human inherited disease erythropoietic protoporphyria.

Continuous long-term immunomodulatory therapy in relapsing multiple sclerosis: results from the 15-year analysis of the US prospective open-label study of glatiramer acetate

The ongoing US Glatiramer Acetate (GA) Trial is the longest evaluation of continuous immunomodulatory therapy in relapsing-remitting multiple sclerosis (RRMS). The objective of this study was to evaluate up to 15 years of GA as a sole disease-modifying therapy. Two hundred and thirty-two patients received at least one GA dose since study initiation in 1991 (mITT cohort), and 100 (43%, Ongoing cohort) continued as of February 2008. Patients were evaluated every 6 months using the Expanded Disability Status Scale (EDSS). Mean GA exposures were 8.6 +/- 5.2, 4.81 +/- 3.69, and 13.6 +/- 1.3 years and mean disease durations were 17, 13, and 22 years for mITT, Withdrawn and Ongoing cohorts, respectively. For Ongoing patients, annual relapse rates (ARRs) maintained a decline from 1.12 +/- 0.82 at baseline to 0.25 +/- 0.34 per year; 57% had stable/improved EDSS scores (change < or = 0.5 points); 65% had not transitioned to secondary progressive multiple sclerosis (SPMS); 38%, 18%, and 3% reached EDSS 4, 6, and 8. For all patients on GA therapy (the mITT cohort), ARRs declined from 1.18 +/- 0.82 to 0.43 +/- 0.58 per year; 54% had stable/improved EDSS scores; 75% had not transitioned to SPMS; 39%, 23%, and 5% reached EDSS 4, 6, and 8. In conclusion, multiple sclerosis patients with mean disease duration of 22 years administering GA for up to 15 years had reduced relapse rates, and decreased disability progression and transition to SPMS. There were no long-term safety issues.

Social support and adaptation to stress by the elderly

The first of a two-phase project is reported that examined the prospective effects of stress and social support on the physical and mental health of the elderly. A sample of 50 elderly subjects was assessed at two points in time over a 6-month period. Results indicated that social support was a significant predictor of physical health status, whereas mental health was related to the Stress X Social Support interaction term. These latter results were consistent with the buffering hypothesis, in that high levels of social support served to reduce the negative impact of stress on mental health. Individuals who were in better mental health at the initial assessment experienced fewer stressful events and higher levels of social support over the subsequent 6-month period. The implications of these findings for research and theory regarding the relation between stress and social support are discussed.

Energy expenditure index of walking for normal children and for children with cerebral palsy

Energy expenditure indices (EEI) based on oxygen uptake and heart rate were used to compare the economy of walking at various speeds by normal and cerebral-palsied children. At low walking speeds, EEI values were high, indicating poor economy. At higher speeds the EEI values decreased until a range of maximum economy was reached. For normal children who were capable of walking beyond this range at higher speeds, the EEI increased again. This pattern was noted for both oxygen-uptake and heart-rate indices. Mean EEI values based on oxygen uptake and heart rate for normal children were significantly lower and occurred at faster walking speeds than values for children with cerebral palsy. EEI based on either oxygen uptake or heart rate can be used clinically to provide objective information to help evaluate the influence on gait function of surgical intervention, ambulatory aids or orthotics.

Prevalence of depression in family caregivers

Family caregivers who sought help to increase their coping skills (N = 158) and caregivers who volunteered for a longitudinal study of Alzheimer's disease (N = 58) were screened for depression. Among help-seekers, 46% had depression according to Research Diagnostic Criteria (RDC), but among non-help-seekers, only 18% met this criterion. In general, women were more depressed than men, but no major differences in the extent of depression were found in those who cared for more impaired persons.

The structure of glutamine-binding protein complexed with glutamine at 1.94 A resolution: comparisons with other amino acid binding proteins

The crystal structure of the glutamine-binding protein (GlnBP) complexed with its ligand (Gln) was determined and refined to 1.94 A resolution. This ellipsoidal protein has two globular domains and is approximately 52 Ax40 Ax35 A in size. The glutamine ligand is located in the cleft between the two domains and stablized by hydrogen bondings and ionic interactions with Asp10, Gly68, Thr70, Ala67, Asp157, Arg75, Lys115, Gly119 and His156. The aliphatic portion of the glutamine ligand is sandwiched in a hydrophobic pocket formed between Phe13 and Phe50 and has 21 van der Waals contacts with GlnBP. Lys115 and His156, that are unique to GlnBP among amino acid binding proteins, apparently contribute to the ligand binding specificity of GlnBP. Asp10 is within 3 A of Lys115. These two residues are over 10 A apart in the ligand-free form of the GlnBP. In addition, GlnBP-Gln exhibits a large-scale movement of the two hinges connecting the two globular domains upon ligand binding. The most significant changes are 41.1 degrees in the phi angle of Gly89 and 34.3 degrees in the psi angle of Glu181 from the first and the second hinge of the protein, respectively. Besides the original six hydrogen bonds, three extra hydrogen bonds can be observed between the two hinge strands upon ligand binding. A hydrogen bond network connects the large domain to the second hinge and a second hydrogen bond network coalesces the small domain to the same strand, both via interaction with the glutamine ligand. Although the two strands of the hinge connecting the domains do not directly participate in the ligand binding, Gln183 and Tyr185 from the second hinge may be involved in the cascade of the conformational change that is induced by ligand binding.

The crystal structure of glutamine-binding protein from Escherichia coli

The crystal structure of the glutamine-binding protein (GlnBP) from Escherichia coli in a ligand-free "open" conformational state has been determined by isomorphous replacement methods and refined to an R-value of 21.4% at 2.3 A resolution. There are two molecules in the asymmetric unit, related by pseudo 4-fold screw symmetry. The refined model consists of 3587 non-hydrogen atoms from 440 residues (two monomers), and 159 water molecules. The structure has root-mean-square deviations of 0.013 A from "ideal" bond lengths and 1.5 degrees from "ideal" bond angles. The GlnBP molecule has overall dimensions of approximately 60 A x 40 A x 35 A and is made up of two domains (termed large and small), which exhibit a similar supersecondary structure, linked by two antiparallel beta-strands. The small domain contains three alpha-helices and four parallel and one antiparallel beta-strands. The large domain is similar to the small domain but contains two additional alpha-helices and three more short antiparallel beta-strands. A comparison of the secondary structural motifs of GlnBP with those of other periplasmic binding proteins is discussed. A model of the "closed form" GlnBP-Gln complex has been proposed based on the crystal structures of the histidine-binding protein-His complex and "open form" GlnBP. This model has been successfully used as a search model in the crystal structure determination of the "closed form" GlnBP-Gln complex by molecular replacement methods. The model agrees remarkably well with the crystal structure of the Gln-GlnBP complex with root-mean-square deviation of 1.29 A. Our study shows that, at least in our case, it is possible to predict one conformational state of a periplasmic binding protein from another conformational state of the protein. The glutamine-binding pockets of the model and the crystal structure are compared and the modeling technique is described.

Structure of the Ca2+-regulated photoprotein obelin at 1.7 A resolution determined directly from its sulfur substructure

The crystal structure of the photoprotein obelin (22.2 kDa) from Obelia longissima has been determined and refined to 1.7 A resolution. Contrary to the prediction of a peroxide, the noncovalently bound substrate, coelenterazine, has only a single oxygen atom bound at the C2-position. The protein-coelenterazine 2-oxy complex observed in the crystals is photo-active because, in the presence of calcium ion, bioluminescence emission within the crystal is observed. This structure represents only the second de novo protein structure determined using the anomalous scattering signal of the sulfur substructure in the crystal. The method used here is theoretically different from that used for crambin in 1981 (4.72 kDa) and represents a significant advancement in protein crystal structure determination.

Complex regional pain syndrome: a narrative review for the practising clinician

Complex regional pain syndrome (CRPS) is a life-altering condition that usually affects the extremities after a trauma or nerve injury. The physiologic changes that occur as a result of the inciting injury are complex, as the name of the syndrome implies. The pain and disability associated with CRPS often lead to psychological co-morbidities that create a vicious cycle of pain, isolation, and depression. We review recent developments in the understanding of CRPS and advancements in management of this syndrome. Further research in targeting specific mechanisms involved in the pathophysiology of CRPS should lead to prevention of this condition.

Sorption of arsenite, arsenate, and thioarsenates to iron oxides and iron sulfides: a kinetic and spectroscopic investigation

Sorption to iron (Fe) minerals determines the fate of the toxic metalloid arsenic (As) in many subsurface environments. Recently, thiolated As species have been shown to dominate aqueous As speciation under a range of environmentally relevant conditions, thus highlighting the need for a quantitative understanding of their sorption behavior. We conducted batch experiments to measure the time-dependent sorption of two S-substituted arsenate species, mono- and tetrathioarsenate, and compared it to the sorption of arsenite and arsenate, in suspensions containing 2-line ferrihydrite, goethite, mackinawite, or pyrite. All four As species strongly sorbed to ferrihydrite. For the other sorbents, binding of the thiolated As species was generally lower compared to arsenate and arsenite, with the exception of the near instantaneous and complete sorption of monothioarsenate to pyrite. Analysis of the X-ray absorption spectroscopy (XAS) spectra of sorbed complexes implied that monothioarsenate binds to Fe oxides as a monodentate, inner-sphere complex. In the presence of Fe sulfides, mono- and tetrathioarsenate were both unstable and partially reduced to arsenite. Adsorption of the thiolated As species to the Fe sulfide minerals also caused the substitution of surface sulfur (S) atoms by As and the formation of As-Fe bonds.