Factors influencing regeneration of retinal ganglion cell axons in adult mammals

Adult retina ganglion cells regrow vigorously their lesioned axons in sciatic nerve segments transplanted at the site of optic nerve transection. In order to determine whether the transplanted peripheral nerve produces secretable substances involved in regeneration, a nerve exudate was collected from the adult sciatic nerve. Transection of the sciatic nervein situ, implantation of silicone tubes around its proximal stump, and additional crush of the nerve further proximal permitted the reinnervation of the nerve stump inside the tube and the release of regeneration-induced substances. Biochemical analysis revealed that several proteins are secreted into the tubes. The fluid contents of the implanted tubes were removed 1 week after implantation and tested for neurotrophic activity in cultures of adult retinae. Massive regrowth of ganglion cell axons has been found in the presence of the nerve exudate. The numbers of axons were significantly higher than these obtained in the presence of nerve and fibroblast growth factors. The results suggest that the lesioned peripheral nerves deliberate during the period of reinnervation substances which also support axonal regrowth of injured central neurons.     

Laparoscopic revision of failed antireflux surgery: a systematic review

Background

Laparoscopic antireflux surgery is an accepted treatment for persistent gastroesophageal reflux but about 4% of patients will eventually require revision surgery.

Methods

We searched The Cochrane Collaboration, Medline, and EMBASE databases, augmented by Google Scholar and PubMed related articles from January 1, 1990, to November 22, 2010. Twenty studies met the inclusion criteria, reporting on 930 surgeries.

Results

The mean surgical duration was 166 minutes and conversion to open revision fundoplication was required in 7% of cases. Complications were reported in 14% of cases and the mean length of stay varied between 1.2 and 6 days. A good to excellent result was reported for 84% of surgeries and 5% of patients required a further revisional procedure.

Conclusions

Laparoscopic revision antireflux surgery appears to be feasible and safe, but subject to somewhat greater risk of conversion, higher morbidity, longer hospital stay, and poorer outcomes than primary laparoscopic fundoplication.     

Conversion and safety in off-pump coronary artery bypass: a system failure that needs re-emphasis

Institution of cardiopulmonary bypass after commencement of "off-pump" coronary artery bypass surgery is known as conversion. This may be an emergency or elective process. The phenomenon of conversion, although widely reported, remains under-emphasized. Emergency conversion may lead to poorer patient outcomes and therefore warrants serious consideration. The rate of conversion may influence the results of randomized controlled trials, and be considered a surrogate performance indicator of surgical competence in off-pump coronary artery bypass. Several causes and predictors of conversion are reported in published literature. This article aims to examine the phenomenon of conversion in off-pump coronary artery bypass and proposes a framework for its prevention.     

Evolution and current applications of the Cabrol procedure and its modifications

Operations on the proximal aorta for aneurysms and dissections almost invariably involve the use of an aortic conduit. The optimal method for safe and effective conduit to the coronary anastomosis has been a matter for debate. Although the modified Bentall procedure with use of ostial aortic "buttons" may provide superior results and currently constitutes the standard of care for aortic root reconstruction, anatomic difficulties such as the closeness of the ostia to the aortic annulus, extreme aortic dilatation/calcification, and reoperations, may hinder the safe and tension-free conduit to the coronary anastomosis. In this technical review we examine the evolution of the Cabrol technique and its modifications, as well as its current indications and related outcomes.     

VEGF, Ang-2 and SRIF associated abnormal postnatal development of the retinal capillary network in the Royal College of Surgeons rat

To examine retinal angiogenesis in the Royal College of Surgeons rat (RCS) serving as a model for ischemic proliferative retinopathies at morphological, proteomic and mRNA levels in order to evaluate the interplay of morphological and molecular changes in the course of the disease.Photoreceptor degeneration was confirmed by histological cross-sections and optical coherence tomography. The capillary retinal network was visualized in RCS rats aged between 14 and 45 days (P14–P45) by perfusion with high molecular weight fluorescein isothiocyanate-labeled dextran and compared with corresponding Sprague-Dawley rats. Vascular crosstalks within central areas to peripheral retinal eccentricities were analyzed. The expression of vascular growth-associated factors and their receptors in the course of the abnormal vascular development, namely vascular endothelial growth factor (VEGF), VEGF receptor subtype 1 (VEGF-R1) and -2 (VEGF-R2), somatostatin (SRIF), somatostatin receptor subtype 2 (Sstr-2), angiopoietin-2 (Ang-2) and tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie-2), was analyzed by immunohistochemistry, western blotting and quantitative real-time polymerase chain reaction.Underperfused areas without capillarization were found in the middle and peripheral retinal eccentricities of RCS rats until P29. Through the course of vascularization previously low perfused areas became completely perfused, but were characterized by significantly increased neovascularizations. Western blotting revealed specific expression of growth-associated factors and their receptors in the course of capillary development. VEGF was significantly increased until P29 in RCS rats, while SRIF was significantly upregulated at P21 and P29 at proteomic level in SD rats. At mRNA level Ang-2 was significantly upregulated in RCS rats at P29, VEGF-R1 and VEGF-R2 at P36 and SRIF at P36.Initial incomplete perfusion is followed by aberrant vessel formation. VEGF, SRIF, Ang-2 and their receptors are regulated at protein and mRNA levels, providing therapeutic possibilities for treating ischemic proliferative retinopathies in the course of the disease.