Second‐look endoscopy with thermal coagulation or injections for peptic ulcer bleeding: A meta‐analysis

Background and Aims: In the management of peptic ulcer bleeding, the benefits of second‐look endoscopic treatment with thermal coagulation or injections in controlling recurrent bleeding is unsure. This study set out to compare efficacy of routine second‐look endoscopy with treatment using either thermal coagulation or injections versus single endoscopy by pooling data from published work. Methods: Full publications in the English‐language published work as well as abstracts in major international conferences were searched over the past 10 years, and six trials fulfilling the search criteria were found. Outcome measurements included: (i) recurrent bleeding; (ii) requirement of surgical intervention; and (iii) mortality. We examined heterogeneity of trials and pooled the effects by meta‐analysis. The quality of studies was graded according to the prospective randomization, methods of patient allocation, the list of exclusion criteria, outcome definitions and the predefined salvage procedures for uncontrolled bleeding. Results: Among 998 patients recruited in these five randomized trials, 119 received routine second‐look endoscopy with thermal coagulation, and 374 received second‐look with endoscopic injection and 505 had single endoscopic therapy. Less recurrent bleeding was reported after thermal coagulation (4.2%) than single endoscopy (15.7%) (relative risk [RR] = 0.29; 95% confidence interval [CI] = 0.11–0.73), but no reduction was reported for the requirement of surgical intervention and all‐cause mortality. Injection therapy did not reduce re‐bleeding (17.6%) when compared to single endoscopy (20.8%; RR = 0.85; 95% CI = 0.63–1.14), requirement for surgery and mortality. Conclusion: Routine second‐look endoscopy with thermal coagulation, but not injection therapy, reduced recurrent peptic ulcer bleeding. There is no proven benefit in reducing surgical intervention and overall mortality.     

The use of yeast to understand TRP-channel mechanosensitivity

Mechanosensitive (MS) ion channels likely underlie myriad force-sensing processes, from basic osmotic regulation to specified sensations of animal hearing and touch. Albeit important, the molecular identities of many eukaryotic MS channels remain elusive, let alone their working mechanisms. This is in stark contrast to our advanced knowledge on voltage- or ligand-sensitive channels. Several members of transient receptor potential (TRP) ion channel family have been implicated to function in mechanosensation and are recognized as promising candidate MS channels. The yeast TRP homolog, TRPY1, is clearly a first-line force transducer. It can be activated by hypertonic shock in vivo and by membrane stretch force in excised patches under patch clamp, making it a useful model for understanding TRP channel mechanosensitivity in general. TRPY1 offers two additional research advantages: (1) It has a large (∼300 pS) unitary conductance and therefore a favorable S/N ratio. (2) Budding yeast allows convenient and efficient genetic and molecular manipulations. In this review, we focus on the current research of TRPY1 and discuss its prospect. We also describe the use of yeast as a system to express and characterize animal TRP channels.     

Bone mineral density enhances use of clinical risk factors in predicting ten-year risk of osteoporotic fractures in Chinese men: the Hong Kong Osteoporosis Study

Summary  

This prospective study aimed to determine the risk factors and the 10-year probability of osteoporotic fracture in Southern Chinese men. The findings show substantial population differences in fracture incidence and risk prediction compared to the FRAX^TM model, and the addition of BMD information to clinical risk factor assessment improved fracture risk prediction in Chinese men.     

Identification and characterization of the tungsten-containing class of benzoyl-coenzyme A reductases

Aromatic compounds are widely distributed in nature and can only be biomineralized by microorganisms. In anaerobic bacteria, benzoyl-CoA (BCoA) is a central intermediate of aromatic degradation, and serves as substrate for dearomatizing BCoA reductases (BCRs). In facultative anaerobes, the mechanistically difficult reduction of BCoA to cyclohexa-1,5-dienoyl-1-carboxyl-CoA (dienoyl-CoA) is driven by a stoichiometric ATP hydrolysis, catalyzed by a soluble, three [4Fe-4S] cluster-containing BCR. In this work, an in vitro assay for BCR from the obligately anaerobic Geobacter metallireducens was established. It followed the reverse reaction, the formation of BCoA from dienoyl-CoA in the presence of various electron acceptors. The benzoate-induced activity was highly specific for dienoyl-CoA (K_m = 24 ± 4 μM). The corresponding oxygen-sensitive enzyme was purified by several chromatographic steps with a 115-fold enrichment and a yield of 18%. The 185-kDa enzyme comprised 73- and 20-kDa subunits, suggesting an α₂β₂-composition. MS analysis revealed the subunits as products of the benzoate-induced bamBC genes. The αβ unit contained 0.9 W, 15 Fe, and 12.5 acid-labile sulfur. Results from EPR spectroscopy suggest the presence of one [3Fe-4S]^0/+1 and three [4Fe-4S]^+1/+2 clusters per αβ unit; oxidized BamBC exhibited an EPR signal typical for a W(V) species. The FeS clusters and the W- cofactor could only be fully reduced by dienoyl-CoA. BamBC represents the prototype of a previously undescribed class of dearomatizing BCRs that differ completely from the ATP-dependent enzymes from facultative anaerobes.     

Recent developments in CD8+ T-lymphocyte memory research.

Appropriately activated CD8+ T cells differentiate into cytotoxic effectors capable of eliminating cancer cells and virally infected cells. Successful generation and maintenance of effective CD8+ T-cell memory, through either natural infection or through vaccination, establishes long-term protection against various pathogenic agents and, therefore, contributes significantly to our health. This report is a review of recent advances in CD8+ T-cell memory research. The pool of memory CD8+ T cells is maintained through a mechanism of rapid turnover that is antigen-independent, class I major histocompatibility complex (MHC I) antigen-dependent, and, potentially, IL-15-dependent. Memory CD8+ T cells, in marked contrast to naive CD8+ T cells, constitutively express cytotoxic effector function in the absence of antigen stimulation. Furthermore, the vast majority of activated CD8+ T cells in mice infected with lymphocytic choriomeningitis virus are antigen-specific, prompting revision of the commonly held view that many antigen-nonspecific CD8+ T cells are activated in response to viral infection. These newly published results not only provide exciting insights into the inner workings of CD8+ memory maintenance, but they also establish a sound foundation for future investigation. As more detailed molecular and cellular mechanisms of the regulation of memory CD8+ T-cell survival emerge, the most exciting challenge will be to apply this understanding toward the rational design of vaccines and immunotherapies. These potentials are even more relevant in view of the critical nature of CD8+ T cells in combating viral infection and cancer, and the relative paucity of effective drugs against these diseases.     

Case Report of a 2-Year-Old Boy With Takayasu’s Arteritis: An Atypical, Severe Presentation of a Rare Disease

Takayasu’s arteritis is a granulomatous giant-cell arteritis of the aorta and its major branches. It primarily affects East Asian women in their second or third decade of life but is well known to affect all ethnicities across the world. Given its systemic nature, Takayasu’s arteritis has multiorgan involvement, with the majority of disease morbidity related to the cardiovascular, central nervous, and renal systems. This report describes an unusual presentation of Takayasu’s arteritis in a 2?-year-old boy. This is the first report in the literature describing the presence of both severe aortic regurgitation and diffuse coronary artery involvement in a patient so young.     

INAUGURAL ARTICLE by a Recently Elected Academy Member:Stiffened lipid platforms at molecular force foci

How mechanical forces are sensed remains largely mysterious. The forces that gate prokaryotic and several eukaryotic channels were found to come from the lipid membrane. Our survey of animal cells found that membrane force foci all have cholesterol-gathering proteins and are reinforced with cholesterol. This result is evident in overt force sensors at the tips of stereocilia for vertebrate hearing and the touch receptor of Caenorhabditis elegans and mammalian neurons. For less specialized cells, cadherins sustain the force between neighboring cells and integrins between cells and matrix. These tension bearers also pass through and bind to a cholesterol-enriched platform before anchoring to cytoskeleton through other proteins. Cholesterol, in alliance with sphingomyelin and specialized proteins, enforces a more ordered structure in the bilayer. Such a stiffened platform can suppress mechanical noise, redirect, rescale, and confine force. We speculate that such platforms may be dynamic. The applied force may allow disordered-phase lipids to enter the platform-staging channel opening in the thinner mobile neighborhood. The platform may also contain specialized protein/lipid subdomains enclosing mechanosensitive channels to open with localized tension. Such a dynamic stage can mechanically operate structurally disparate channels or enzymes without having to tie them directly to cadherin, integrin, or other protein tethers.