Role of lysine dimethylation in Bcl-2 function and T cell activation (LYM4P.744)

Bcl-2 is an anti-apoptotic protein that can protect developing and mature T cells from apoptosis. Interaction between anti-apoptotic and pro-apoptotic members of Bcl-2 family proteins is a key event in the regulation of apoptosis. Using mass spectroscopy to analyze a murine T cell line, we identified dimethylation of two lysine residues, K17 and K22, in the BH4 domain of Bcl-2, a domain critical for its anti-apoptotic function. Mutation of K22 (but not K17) to alanine abrogated Bcl-2 binding to pro-apoptotic proteins and greatly reduced Bcl-2 anti-apoptotic function in cytokine withdrawal. This assigns functional importance to K22, which is conserved across species and other anti-apoptotic members, and suggests that dimethylation could affect its function. Structure model of Bcl-2 was generated using computer simulation. The Bcl-2 model showed that the K22 appears to be involved in stabilizing peptide secondary structure, rather than directly interacting with pro-apoptotic proteins. With our newly developed monoclonal antibody to detect the K22 dimethylation of Bcl-2, dimethylated Bcl-2 was found in murine T and B cells, but not in thymocytes. There is no evidence that the dimethylation of Bcl-2 is regulated by IL-7, a growth factor required for T cell development and homeostasis. Anti-CD3 stimulation abolished Bcl-2 dimethylation in CD4 or CD8 cells. This suggests that Bcl-2 dimethylation may regulate activated T cell apoptosis but not be involved in thymic development.

Intestinal microbiota influence the early postnatal development of the enteric nervous system

BACKGROUND

Normal gastrointestinal function depends on an intact and coordinated enteric nervous system (ENS). While the ENS is formed during fetal life, plasticity persists in the postnatal period during which the gastrointestinal tract is colonized by bacteria. We tested the hypothesis that colonization of the bowel by intestinal microbiota influences the postnatal development of the ENS.

METHODS

The development of the ENS was studied in whole mount preparations of duodenum, jejunum, and ileum of specific pathogen-free (SPF), germ-free (GF), and altered Schaedler flora (ASF) NIH Swiss mice at postnatal day 3 (P3). The frequency and amplitude of circular muscle contractions were measured in intestinal segments using spatiotemporal mapping of video recorded spontaneous contractile activity with and without exposure to lidocaine and N-nitro-L-arginine (NOLA).

KEY RESULTS

Immunolabeling with antibodies to PGP9.5 revealed significant abnormalities in the myenteric plexi of GF jejunum and ileum, but not duodenum, characterized by a decrease in nerve density, a decrease in the number of neurons per ganglion, and an increase in the proportion of myenteric nitrergic neurons. Frequency of amplitude of muscle contractions were significantly decreased in the jejunum and ileum of GF mice and were unaffected by exposure to lidocaine, while NOLA enhanced contractile frequency in the GF jejunum and ileum.

CONCLUSIONS & INFERENCES

These findings suggest that early exposure to intestinal bacteria is essential for the postnatal development of the ENS in the mid to distal small intestine. Future studies are needed to investigate the mechanisms by which enteric microbiota interact with the developing ENS.

Patient satisfaction after primary total and unicompartmental knee arthroplasty: an age-dependent analysis

BACKGROUND

Patient-related outcomes have become the focus of increased attention when assessing knee arthroplasty.

METHODS

We retrieved questionnaires from 485 (584 knees) patients at a minimum of 3years after undergoing primary knee arthroplasty. We excluded bilateral knee arthroplasty, leaving 141 UKA and 245 TKA who rated their satisfaction and expectation regarding pain, range of motion (ROM), daily living function (DLF), return to recreational activity (RRA) and ability to kneel (ATK) on a scale of 0 (worst) to 10 (best). We further collected data on pain level and the modified Cincinnati rating scale. Range of motion was documented pre- and postoperatively at a minimum of six months. The cohort was subdivided into three age groups and compared with each other (Group 1: <55, n=113; Group 2: 55-64, n=117; Group 3: 65+, n=155).

RESULTS

Average satisfaction with pain, ROM and ATK for patients under 55 was higher for UKA than for TKA. Patients>65 with TKA were on average more satisfied than patients with UKA in these three items. However, patients under 55 with UKA were up to 2.9 times more likely to have their expectations met when compared to patients receiving TKA. Patients with UKA under 55 rated their joint as good/excellent in 96.0% versus patients in the same age group with TKA in 81.0%.

CONCLUSIONS

We found that overall, younger patients who were treated with UKA demonstrated higher satisfaction scores in most subsets when compared with the patients of the same age group who received TKA.

A cascade classifier for diagnosis of melanoma in clinical images

Computer aided diagnosis of medical images can help physicians in better detecting and early diagnosis of many symptoms and therefore reducing the mortality rate. Realization of an efficient mobile device for semi-automatic diagnosis of melanoma would greatly enhance the applicability of medical image classification scheme and make it useful in clinical contexts. In this paper, interactive object recognition methodology is adopted for border segmentation of clinical skin lesion images. In addition, performance of five classifiers, KNN, Naïve Bayes, multi-layer perceptron, random forest and SVM are compared based on color and texture features for discriminating melanoma from benign nevus. The results show that a sensitivity of 82.6% and specificity of 83% can be achieved using a single SVM classifier. However, a better classification performance was achieved using a proposed cascade classifier with the sensitivity of 83.06% and specificity of 90.05% when performing ten-fold cross validation.

The intensity of QuantiFERON TB-gold response does not differentiate active from latent tuberculosis

We analyzed positive QuantiFERON (QFT) assays, performed between July 2009 and April 2011 in the Mercy University Hospital, Cork, Ireland, which included, 94 patients with latent tuberculosis (LTBI) and 35 patients with active tuberculosis. There was no difference in the intensity of response between patients with LTBI and active tuberculosis (p = 0.1589). In patients with LTBI, there were no correlations between age (p = 0.353), sex (p = 0.476), smoking (p = 0.323), contact (p = 0.612), Mantoux response (p = 0.055), Irish nationality (p=0.768), previous BCG vaccination (p = 0.504), WCC (p = 0.187), lymphocyte count (p = 0.786), neutrophil count (p = 0.157) and the intensity of QFT response. Similarly in patients with active TB, there were no correlations between these variables and QFT response. The intensity of QFT response does not help to differentiate active from LTBI. The intensity of QFT response is not influenced by age, sex, smoking, remoteness of contact history, Mantoux response, nationality, CXR abnormalities, BCG vaccination and peripheral lymphocyte count.

Altered colonic function and microbiota profile in a mouse model of chronic depression

BACKGROUND

Depression often coexists with the irritable bowel syndrome (IBS) which is characterized by alterations in gut function. There is emerging evidence that the microbial composition (microbiota) of the gut is altered in IBS, but the basis for this is poorly understood. The aim of this study was to determine whether the induction of chronic depression results in changes in the colonic function and in its microbial community, and to explore underlying mechanisms.

METHODS

Bilateral olfactory bulbectomy (OBx) was used to induce depression-like behavior in mice. Colonic function was assessed by measuring muscle contractility, pellet excretion, c-fos activity, and serotonin levels. Microbiota profiles were obtained using denaturing gradient gel electrophoresis (DGGE). The hypothalamic-pituitary axis (HPA) was assessed by the hypothalamic expression of corticotropin-releasing hormone (CRH). In separate studies, mice without OBx received CRH via intracerebroventricular (ICV) infusion for 4 weeks prior to assessing colonic function and microbiota profiles.

KEY RESULTS

Olfactory bulbectomy mice demonstrated chronic depression- and anxiety-like behaviors associated with elevated central CRH expression and increases in c-Fos activity, serotonin levels, and motility in the colon. These changes were accompanied by an altered intestinal microbial profile. Central CRH administration produced similar changes in behavior and motility and altered the microbiota profile in the colon.

CONCLUSIONS & INFERENCES

The induction of chronic depression alters motor activity and the microbial profile in the colon likely via activation of the HPA. These findings provide a basis for linking the behavioral and gastrointestinal manifestations of IBS.

Head circumferences in twins with and without Autism Spectrum Disorders

To determine the genetic relationship between head circumference (HC) and Autism Spectrum Disorders (ASDs). Twin pairs with at least one twin with an ASD were assessed. HCs in affected and unaffected individuals were compared, as were HC correlations in monozygotic and dizygotic pairs. 404 subjects, ages 4-18, were included. 20 % of males and 27 % of females with an ASD had macrocephaly. Unaffected co-twins showed similar rates (16 % of males and 22 % of females). Statistical analysis revealed no significant difference in HCs between affected and unaffected twins. Twins with ASDs and unaffected co-twins have similar HCs and increased rates of macrocephaly. Correlations demonstrated partial inheritance of HCs. Thus, macrocephaly may represent an endophenotype in ASDs.

Decoding nitric oxide release rates of amine-based diazeniumdiolates

Amine-based diazeniumdiolates (NONOates) have garnered widespread use as nitric oxide (NO) donors, and their potential for nitroxyl (HNO) release has more recently been realized. While NO release rates can vary significantly with the type of amine, half-lives of seconds to days under physiological conditions, there is as yet no way to determine a priori the NO or HNO production rates of a given species, and no discernible trends have manifested other than that secondary amines produce only NO (i.e., no HNO). As a step to understanding these complex systems, here we describe a procedure for modeling amine-based NONOates in water solvent that provides an excellent correlation (R(2) = 0.94) between experimentally measured dissociation rates of seven secondary amine species and their computed NO release activation energies. The significant difference in behavior of NONOates in the gas and solvent phases is also rigorously demonstrated via explicit additions of quantum mechanical water molecules. The presented results suggest that the as-yet unsynthesized simplest amine-based NONOate, the diazeniumdiolated ammonia anion [H2N-N(O)═NO(-)], could serve as an unperturbed HNO donor. These results provide a step forward toward the accurate modeling of general NO and/or HNO donors as well as for the identification of tailored prodrug candidates.

Global epidemiology of amyotrophic lateral sclerosis: a systematic review of the published literature

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is relatively rare, yet the economic and social burden is substantial. Having accurate incidence and prevalence estimates would facilitate efficient allocation of healthcare resources.

OBJECTIVE

To provide a comprehensive and critical review of the epidemiological literature on ALS.

METHODS

MEDLINE and EMBASE (1995-2011) databases of population-based studies on ALS incidence and prevalence reporting quantitative data were analyzed. Data extracted included study location and time, design and data sources, case ascertainment methods and incidence and/or prevalence rates. Medians and interquartile ranges (IQRs) were calculated, and ALS case estimates were derived using 2010 population estimates.

RESULTS

In all, 37 articles met the inclusion criteria. In Europe, the median incidence rate (/100,000 population) was 2.08 (IQR 1.47-2.43), corresponding to an estimated 15,355 (10,852-17,938) cases. Median prevalence (/100,000 population) was 5.40 (IQR 4.06-7.89), or 39,863 (29,971-58,244) prevalent cases.

CONCLUSIONS

Disparity in rates among ALS incidence and prevalence studies may be due to differences in study design or true variations in population demographics such as age and geography, including environmental factors and genetic predisposition. Additional large-scale studies that use standardized case ascertainment methods are needed to more accurately assess the true global burden of ALS.

Effect of ribotype on all-cause mortality following Clostridium difficile infection

BACKGROUND

Clostridium difficile infection (CDI) is significantly associated with subsequent all-cause mortality. Although a number of studies have investigated mortality associated with CDI, few have compared all-cause mortality between ribotypes.

AIM

We aimed to estimate all-cause mortality following CDI and to investigate the relationship between mortality, ribotype and other available variables.

METHODS

We undertook a retrospective cohort study. All patients with toxin-positive CDI in North East England between July 2009 and June 2011 were matched to death registration data. Differences in all-cause 30-day case fatality were explored using Poisson regression with robust error variances. For survival analysis, an accelerated failure time model with generalized gamma distribution was chosen.

FINDINGS

In total, 1426 patients were included. All-cause case fatality was 10.2%, 16.4%, 25.7% and 38.1% at 7, 14, 30 and 90 days respectively. In multivariate analysis, ribotype 027 (risk ratio: 1.34; 95% confidence interval: 1.02-1.75) and ribotype 015 (0.46; 0.26-0.82) were significantly associated with higher and lower all-cause 30-day case fatality rates, respectively. In survival analysis, only ribotype 015 had significantly lower predicted mortality (P = 0.008). Patients whose infection was hospital-acquired had significantly higher predicted mortality (P < 0.001).

CONCLUSION

This is the first population-based study of comparative mortality between multiple ribotypes. Our study identified a high rate of all-cause mortality following CDI. We found evidence of variability in mortality between ribotypes in this cohort with mortality significantly higher for ribotype 027 at 30 days following diagnosis and significantly lower for ribotype 015.

A rapid, novel method of volumetric assessment of MRI-detected subchondral bone marrow lesions in knee osteoarthritis

PURPOSE

To assess reliability and validity of a semi-automated quantitative method for osteoarthritis (OA)-related bone marrow lesion (BML) assessment in the femur and tibia.

METHODS

In a cross-sectional study of subjects with knee OA, we examined concurrent criterion and clinical validation of a novel method of semi-automated quantitative BML measurement. The primary outcome was total segmented BML volume in femoral and tibial medial and lateral knee compartments. Criterion validation was examined through comparison of BML volumes with Whole-Organ Magnetic Resonance Imaging Score (WORMS) scoring. Clinical validation was examined via associations of tibial and femoral BML volume with the Western Ontario and McMaster University OA Index weight-bearing pain questions.

RESULTS

Among the 115 subjects, mean age was 62 years, mean BMI 30.4 (kg/m(2)), 84% were white and 52% male. The intra-class correlation coefficients (ICC) for intra-reader reliability was 0.96 and 0.97 for inter-reader reliability. Significant Spearman's correlations were found between segmented BML volume and WORMS BML scoring for tibial medial (0.75) and lateral (0.73) compartments, and for femoral medial (0.72) and lateral (0.88) compartments. Significant positive associations were found between weight-bearing pain and total femoral BML volume (P < 0.003), but not total tibial BML (P < 0.101).

CONCLUSION

We have documented a moderately strong correlation between a novel measurement method of femoral and tibial BML volume and semi-quantitative WORMS scores, providing evidence of criterion validity. The hypothesis that weight-bearing pain was associated with BML volume was confirmed for total femoral BML volume but not total tibial BML volume. The lack of association between tibial BML volume and pain requires further investigation.

Lysine dimethylation in the BH4 domain of Bcl-2 and functional significance (P1306)

Bcl-2 is an anti-apoptotic protein that can protect developing and mature T cells against a variety of apoptotic signals. The Bcl-2 family of proteins, compromised of anti-apoptotic as well as pro-apoptotic members, plays key roles in apoptosis; the balance of these members determines cell survival. Anti-apoptotic Bcl-2 contains four conserved Bcl-2 homology (BH) domains and the BH4 domain is indispensable for its ability to suppress cell death. Using mass spectroscopy to analyze a murine T cell line, we identified dimethylation of two lysine residues in the BH4 domain: K17 and K22. Mutation of K22 (but not K17) to alanine abrogated Bcl-2 binding to pro-apoptotic proteins Bax, Bak, Bad, Bim and Puma and greatly reduced Bcl-2 anti-apoptotic function in cytokine withdrawal. This assigns functional importance to K22 (which is conserved across species and other anti-apoptotic members) and suggests that dimethylation could affect its function. K22, based on structural models, appears to be involved in stabilizing peptide secondary structure, rather than directly interacting with pro-apoptotic proteins. We developed a monoclonal antibody that recognizes dimethylated K22 in the Bcl-2 sequence and detected expression in murine B cells (but not thymocytes). This suggests that Bcl-2 dimethylation may regulate B cell survival.