Dimethyl 3,3'-dithiobispropionimidate: a novel crosslinking reagent for collagen

Crosslinking agents are used for improving the physical properties and durability of collagenous implants, glutaraldehyde (GTA) being the most widely used. Many of these reagents, including GTA, are known to be cytotoxic and to induce calcification. Hence, it is desirable to develop new crosslinking methods for collagen, so that biocompatibility and physical properties are improved. In the present study, dimethyl 3,3' -dithiobispropionimidate (DTBP) has been tried as a novel crosslinking reagent for collagen. Collagen purified from rat tail tendon has been crosslinked with DTBP and GTA. An increase of 22 degrees C in shrinkage temperature is observed for collagen treated with DTBP under optimal conditions. Crosslinking density determination shows that DTBP induces 10 crosslinks per mole, compared to 13 by GTA. While the tensile strength of GTA-treated samples is greater than those treated with DTBP, the latter shows more extensibility. In vitro degradation studies show that both GTA- and DTBP-treated samples are resistant to degradation by collagenase. The biocompatibility of crosslinked collagen samples studied by subcutaneous implantation in rats show that while both GTA- and DTBP-treated collagen do not degrade for up to 4 weeks, ultrastructural and histological studies indicate that DTBP collagen is far more biocompatible than GTA-treated matrices.     

Review and Meta-analysis of Emerging Risk Factors for Agricultural Injury

Agricultural injury is a significant public health problem globally. Extensive research has addressed this problem, and a growing number of risk factors have been reported. The authors evaluated the evidence for frequently reported risk factors earlier. The objective in the current study was to identify emerging risk factors for agricultural injury and calculate pooled estimates for factors that were assessed in two or more studies. A total of 441 (PubMed) and 285 (Google Scholar) studies were identified focusing on occupational injuries in agriculture. From these, 39 studies reported point estimates of risk factors for injury; 38 of them passed the Newcastle-Ottawa criteria for quality and were selected for the systematic review and meta-analysis. Several risk factors were significantly associated with injury in the meta-analysis. These included older age (vs. younger), education up to high school or higher (vs. lower), non-Caucasian race (vs. Caucasian), Finnish language (vs. Swedish), residence on-farm (vs. off-farm), sleeping less than 7–7.5 hours (vs. more), high perceived injury risk (vs. low), challenging social conditions (vs. normal), greater farm sales, size, income, and number of employees on the farm (vs. smaller), animal production (vs. other production), unsafe practices conducted (vs. not), computer use (vs. not), dermal exposure to pesticides and/or chemicals (vs. not), high cooperation between farms (vs. not), and machinery condition fair/poor (vs. excellent/good). Eighteen of the 25 risk factors were significant in the meta-analysis. The identified risk factors should be considered when designing interventions and selecting populations at high risk of injury.     

An Unusual Cause of Cardioembolic Stroke: Paradoxical Embolism Due to Thrombus Formation on the Eustachian Valve

Cardioembolism is an important cause of ischemic stroke, with several studies showing worse outcome than following other stroke subtypes. Paradoxical embolism is a rare cause of cardioembolic stroke. We report a case of a patient with presumed paradoxical cardioembolic stroke secondary to thrombus formation on the eustachian valve remnant in the right atrium. The patient was anticoagulated with resolution of the mass upon follow‐up assessment. The diagnostic, investigative and management strategies are discussed for patients with suspected paradoxical embolism causing stroke. Physicians are reminded of the utility of echocardiography for identifying potential cardioembolic etiologies, including both transthoracic and transesophageal echocardiography.     

Heat transport in bubbling turbulent convection

Boiling is an extremely effective way to promote heat transfer from a hot surface to a liquid due to numerous mechanisms, many of which are not understood in quantitative detail. An important component of the overall process is that the buoyancy of the bubble compounds with that of the liquid to give rise to a much-enhanced natural convection. In this article, we focus specifically on this enhancement and present a numerical study of the resulting two-phase Rayleigh–Bénard convection process in a cylindrical cell with a diameter equal to its height. We make no attempt to model other aspects of the boiling process such as bubble nucleation and detachment. The cell base and top are held at temperatures above and below the boiling point of the liquid, respectively. By keeping this difference constant, we study the effect of the liquid superheat in a Rayleigh number range that, in the absence of boiling, would be between 2 × 10⁶ and 5 × 10⁹. We find a considerable enhancement of the heat transfer and study its dependence on the number of bubbles, the degree of superheat of the hot cell bottom, and the Rayleigh number. The increased buoyancy provided by the bubbles leads to more energetic hot plumes detaching from the cell bottom, and the strength of the circulation in the cell is significantly increased. Our results are in general agreement with recent experiments on boiling Rayleigh–Bénard convection.     

Eri1 regulates microRNA homeostasis and mouse lymphocyte development and antiviral function

Natural killer (NK) cells play a critical role in early host defense to infected and transformed cells. Here, we show that mice deficient in Eri1, a conserved 3'-to-5' exoribonuclease that represses RNA interference, have a cell-intrinsic defect in NK-cell development and maturation. Eri1(-/-) NK cells displayed delayed acquisition of Ly49 receptors in the bone marrow (BM) and a selective reduction in Ly49D and Ly49H activating receptors in the periphery. Eri1 was required for immune-mediated control of mouse CMV (MCMV) infection. Ly49H(+) NK cells deficient in Eri1 failed to expand efficiently during MCMV infection, and virus-specific responses were also diminished among Eri1(-/-) T cells. We identified miRNAs as the major endogenous small RNA target of Eri1 in mouse lymphocytes. Both NK and T cells deficient in Eri1 displayed a global, sequence-independent increase in miRNA abundance. Ectopic Eri1 expression rescued defective miRNA expression in mature Eri1(-/-) T cells. Thus, mouse Eri1 regulates miRNA homeostasis in lymphocytes and is required for normal NK-cell development and antiviral immunity.     

Preliminary study on the antimicrobial activity of Enicostemma littorale using different solvents

ObjectiveTo study the antimicrobial activity of Enicostemma littorale (E. littorale) using different solvents.MethodsChloroform, methanol and acetone extracts of different parts of E. littorale (leaf, stem and root) were evaluated for antimicrobial activity using disc diffusion method against some gram-negative species such as Escherichia coli, Klebsiella pnemoniae, Pseudomonas aeruginosa, Salmonella typhi and gram-positive species Staphylococcus aureus, Bacillus cereus, Bacillus subtilis and two fugal species viz., Aspergillus fumigates and Aspergillus flavus.ResultsThe chloroform extracts showed the highest antibacterial activity. Among leaf, stem and root extracts, the stem extracts showed maximum antibacterial activity. All of the used extracts had no significant antifungal activity against Aspergillus fumigates and Aspergillus flavus. The chloroform stem extract showed highest activity (about 20 mm inhibition zone) against Bacillus subtilis (at 500 mg/mL) followed by the methanolic stem extract which showed highest activity against the same organism. The lowest antibacterial activity was observed by the acetone leaf extract (about 8 mm inhibition zone) against Escherichia coli.ConclusionThe findings of the study indicate littorale could also be a new source for antibiotics discovery.