Investigation of the influence of the interaction between anionic detergents and a copolymer of n-vinyl-2-pyrrolidone with vinylamine on the biological activity of these detergents

The interactions between sodium dodecyl- and tetradecylsulfater or sodium alkylbenzenesulfonate and a copolymer of N-vinylpyrrolidone with vinylamine (9 : 1 by mole) in aqueous solution were investigated by polarized luminescene. Polymer complexes of these anionic detergents with the copolymer were obtained and their antimicrobial and toxic properties as well as their effect on a bacterial enzyme, penicillinase, were investigated, It was found that these polymer complexes do not disintegrate on passing from aqueous to salt solutions, are 4 to 5 times less toxic than the initial anionic detergents and are comparable to the latter in both their antimicrobial activity and the ability for inhibiting penicillinase.     

Platelet-rich plasma in tendon-related disorders: results and indications

Purpose

Platelet-rich plasma (PRP) is currently the most exploited strategy in the clinical practice to provide a regenerative stimulus for tendon healing. The aim of the present study was to systematically review the available evidence on the treatment of the main tendon disorders where PRP is currently applied.

Methods

A systematic review of the literature was performed on the use of PRP as a treatment for tendinopathies focusing on the following sites: Achilles tendon, patellar tendon, rotator cuff tendons, and lateral elbow tendons. The following inclusion criteria for relevant articles were used: clinical trials written in English language up to 21 June 2016 on the use of PRP in the conservative or surgical treatment of the aforementioned tendinopathies.

Results

The research identified the following clinical trials dealing with the application of PRP in the selected tendons: 19 papers on patellar tendon (6 being RCTs: 4 dealing with PRP conservative application and 2 surgical), 24 papers on Achilles tendon (4 RCTs: 3 conservative and 1 surgical), 29 on lateral elbow tendons (17 RCTs, all conservative), and 32 on rotator cuff (22 RCTs: 18 surgical and 3 conservative).

Conclusion

Patellar tendons seem to benefit from PRP injections, whereas in the Achilles tendon, PRP application is not indicated neither as a conservative approach nor as a surgical augmentation. Lateral elbow tendinopathy showed an improvement in most of the high-level studies, but the lack of proven superiority with respect to the more simple whole-blood injections still questions its use in the clinical practice. With regard to rotator cuff pathology, the vast majority of surgical RCTs documented a lack of beneficial effects, whereas there is still inconclusive evidence concerning its conservative application in rotator cuff disorders.

Level of evidence

Systematic review of level I–IV trials, Level IV.

     

Platelet-rich plasma (PRP) to treat sports injuries: evidence to support its use

Tissue repair in musculoskeletal lesions is often a slow and sometimes incomplete process. In sports patients or professional athletes, the impact of musculoskeletal lesions on life and work is great, and the fast recovery of full efficiency and return to competition is of primary importance. The clinical improvement offered by available treatments is not always sufficient for highly demanding patients to return to their previous level of activity. The search for a minimally invasive solution to improve the status of the chondral surface of the injured joint is therefore highly desirable, especially in these patients. Platelet-rich plasma (PRP) is a procedure that allows to obtain a natural concentration of autologous growth factors. The attractive possibility to use the patients’ own growth factors to enhance reparative process in tissues with low healing potential, the promising preliminary clinical findings and the safety of these methods, explain the wide application of this biological approach. The aim of this review is to analyse the existing published studies to look for scientific evidence in preclinical studies or in the results obtained through PRP application in humans that supports the efficacy of PRP and its use for the treatment of tendinous, ligamentous, cartilaginous and muscular injuries. The analysis of the literature shows promising preclinical results but contradictory clinical findings for the treatment of sport injuries. High-quality studies are required to confirm these preliminary results and provide scientific evidence to support its use.     

Direct activation of full-length proapoptotic BAK

Proapoptotic B-cell lymphoma 2 (BCL-2) antagonist/killer (BAK) and BCL-2–associated X (BAX) form toxic mitochondrial pores in response to cellular stress. Whereas BAX resides predominantly in the cytosol, BAK is constitutively localized to the outer mitochondrial membrane. Select BCL-2 homology domain 3 (BH3) helices activate BAX directly by engaging an α1/α6 trigger site. The inability to express full-length BAK has hampered full dissection of its activation mechanism. Here, we report the production of full-length, monomeric BAK by mutagenesis-based solubilization of its C-terminal α-helical surface. Recombinant BAK autotranslocates to mitochondria but only releases cytochrome c upon BH3 triggering. A direct activation mechanism was explicitly demonstrated using a liposomal system that recapitulates BAK-mediated release upon addition of BH3 ligands. Photoreactive BH3 helices mapped both triggering and autointeractions to the canonical BH3-binding pocket of BAK, whereas the same ligands crosslinked to the α1/α6 site of BAX. Thus, activation of both BAK and BAX is initiated by direct BH3–interaction but at distinct trigger sites. These structural and biochemical insights provide opportunities for developing proapoptotic agents that activate the death pathway through direct but differential engagement of BAK and BAX.