Chitosan-Based Membranes for Skin Wound Repair in a Dorsal Fold Chamber Rat Model

Frequently, deep partial and full-thickness skin wounds do not spontaneously regenerate. To restore the normal function of skin, epidermal and dermal components have to be supplied to the wound bed by grafting various substrates. Available options are limited and frequently costly. Herein, authors present a possible approach using 3D skin scaffolds capable of mimicking structure and biological functions of the extracellular matrix, providing, in parallel, a good environment for cell attachment, proliferation and differentiation. Low-molecular weight chitosan-based membranes were prepared by freeze-drying and ionizing radiation techniques to be used as skin scaffolds. Poly (vinyl alcohol), PVA, vinyl pyrrolidone, VP, and gelatin from cold water fish were incorporated. Information regarding membranes’ physical-chemical properties from SEM analysis, swelling and weight loss, together with biological response through in vitro assays (using Human Caucasian Fetal Foreskin Fibroblast) allowed the selection of an optimized batch of membranes that was used as skin scaffold in a dorsal rat model wound. The in vivo implantation assays (in Wistar rats) resulted in very promising results: (i) healing process faster than control; (ii) good vascularization; (iii) viable new tissues morphologically functional.info:eu-repo/semantics/publishedVersio

Magnetic Precipitation: A New Platform for Protein Purification

PD/BD/105753/2014 UIDB/ 04378/2020 POCI-01-0145-FEDER-007728 PTDC/BII-BIO/28878/2017One of the trends in downstream processing comprises the use of “anything-but-chromatography” methods to overcome the current downfalls of standard packed-bed chromatography. Precipitation and magnetic separation are two techniques already proven to accomplish protein purification from complex media, yet never used in synergy. With the aim to capture antibodies directly from crude extracts, a new approach combining precipitation and magnetic separation is developed and named as affinity magnetic precipitation. A precipitation screening, based on the Hofmeister series, and a commercial precipitation kit are tested with affinity magnetic particles to assess the best condition for antibody capture from human serum plasma and clarified cell supernatant. The best conditions are obtained when using PEG3350 as precipitant at 4 °C for 1 h, reaching 80% purity and 50% recovery of polyclonal antibodies from plasma, and 99% purity with 97% recovery yield of anti-TNFα mAb from cell supernatants. These results show that the synergetic use of precipitation and magnetic separation can represent an alternative for the efficient capture of antibodies.authorsversionpublishe

Serum brain-derived neurotrophic factor and clozapine daily dose in patients with schizophrenia: A positive correlation

AbstractBrain-derived neurotrophic factor (BDNF) plays a critical role in neurodevelopment and neuroplasticity. Altered BDNF signaling is thought to contribute to the pathogenesis of schizophrenia (SZ) especially in relation to cognitive deficits. Clozapine (CLZ) has been shown a beneficial effect on cognition in SZ in some studies and a detrimental effect in others. To examine serum BDNF, two groups of chronically medicated DSM-IV SZ patients (n=44), on treatment with clozapine (n=31) and typical antipsychotics (n=13) had 5ml blood samples collected by venipuncture. Serum BDNF levels were significantly correlated with CLZ daily dose (r=0.394, p=0.028), but not with typical antipsychotic daily dose (r=0.208, p=0.496). This study suggests that serum BDNF levels are correlated with CLZ daily dose, and this may lead to the cognitive enhancement as seen in patients with SZ under CLZ. Despite the strong evidence that chronic administration of CLZ is effective for patients with SZ, it is still unknown whether atypical antipsychotic drugs regulate BDNF expression. Serum BDNF levels concentration in SZ merits further investigations with regard to the role of neurotrophins in the cognitive response to treatment with CLZ and other atypical antipsychotics

Reconstruction of a 10-mm-long median nerve gap in an ischemic environment using autologous conduits with different patterns of blood supply: A comparative study in the rat

The aim of this study was to evaluate in the Wistar rat the efficacy of various autologous nerve conduits with various forms of blood supply in reconstructing a 10-mm-long gap in the median nerve (MN) under conditions of local ischemia. A 10-mm-long median nerve defect was created in the right arm. A loose silicone tube was placed around the nerve gap zone, in order to simulate a local ischemic environment. Rats were divided in the following experimental groups (each with 20 rats): the nerve Graft (NG) group, in which the excised MN segment was reattached; the conventional nerve flap (CNF) and the arterialized neurovenous flap (ANVF) groups in which the gap was bridged with homonymous median nerve flaps; the prefabricated nerve flap (PNF) group in which the gap was reconstructed with a fabricated flap created by leaving an arteriovenous fistula in contact with the sciatic nerve for 5 weeks; and the two control groups, Sham and Excision groups. In the latter group, the proximal stump of the MN nerve was ligated and no repair was performed. The rats were followed for 100 days. During this time, they did physiotherapy. Functional, electroneuromyographic and histological studies were performed. The CNF and ANVF groups presented better results than the NG group in the following assessments: grasping test, nociception, motor stimulation threshold, muscle weight, and histomorphometric evaluation. Radial deviation of the operated forepaw was more common in rats that presented worse results in the other outcome variables. Overall, CNFs and ANVFs produced a faster and more complete recovery than NGs in the reconstruction of a 10-mm-long median nerve gap in an ischemic environment in the Wistar rat. Although, results obtained with CNFs were in most cases were better than ANVFs, these differences were not statistically significant for most of the outcome variables.publishersversionpublishe

BD-2 and BD-3 increase skin flap survival in a model of ischemia and Pseudomonas aeruginosa infection

The main aim of this work was to study the usefulness of human β-defensins 2 (BD-2) and 3 (BD-3), which are part of the innate immune system, in the treatment of infected ischemic skin flaps. We investigated the effect of transducing rat ischemic skin flaps with lentiviral vectors encoding human BD-2, BD-3, or both BD-2 and BD-3, to increase flap survival in the context of a P. aeruginosa infection associated with a foreign body. The secondary endpoints assessed were: bacterial counts, and biofilm formation on the surface of the foreign body. A local ischemic environment was created by producing arterialized venous flaps in the left epigastric region of rats. Flaps were intentionally infected by placing underneath them two catheters with 105 CFU of P. aeruginosa before the surgical wounds were hermetically closed. Flap biopsies were performed 3 and 7 days post-operatively, and the specimens submitted to immunohistochemical analysis for BD-2 and BD-3, as well as to bacterial quantification. Subsequently, the catheter segments were analyzed with scanning electron microscopy (SEM). Flaps transduced with BD-2 and BD-3 showed expression of these defensins and presented increased flap survival. Rats transduced with BD-3 presented a net reduction in the number of P. aeruginosa on the surface of the foreign body and lesser biofilm formation.publishersversionpublishe

Blood Supply to the Integument of the Abdomen of the Rat: A Surgical Perspective

Background:. Many fundamental questions regarding the blood supply to the integument of the rat remain to be clarified, namely the degree of homology between rat and humans. The aim of this work was to characterize in detail the macro and microvascular blood supply to the integument covering the ventrolateral aspect of the abdominal wall of the rat. Methods:. Two hundred five Wistar male rats weighing 250–350 g were used. They were submitted to gross anatomical dissection after intravascular colored latex injection (n = 30); conversion in modified Spalteholz cleared specimens (n=10); intravascular injection of a Perspex solution, and then corroded, in order to produce vascular corrosion casts of the vessels in the region (n = 5); histological studies (n = 20); scanning electron microscopy of vascular corrosion casts (n = 10); surgical dissection of the superficial caudal epigastric vessels (n = 100); and to thermographic evaluation (n = 30). Results:. The ventrolateral abdominal wall presented a dominant superficial vascular system, which was composed mainly of branches from the superficial caudal epigastric artery and vein in the caudal half. The cranial half still received significant arterial contributions from the lateral thoracic artery in all cases and from large perforators coming from the intercostal arteries and from the deep cranial epigastric artery. Conclusions:. These data show that rats and humans present a great deal of homology regarding the blood supply to the ventrolateral aspect of the abdominal integument. However, there are also significant differences that must be taken into consideration when performing and interpreting experimental procedures in rats

Pharmacological treatment and staging in bipolar disorder : evidence from clinical practice

Objective: Staging models for medical diseases are widely used to guide treatment and prognosis. Bipolar disorder (BD) is a chronic condition and it is among the most disabling disorders in medicine. The staging model proposed by Kapczinski in 2009 presents four progressive clinical stages of BD. Our aim was to evaluate pharmacological maintenance treatment across these stages in patients with BD. Methods: One hundred and twenty-nine subjects who met DSM-IV criteria for BD were recruited from the Bipolar Disorders Program at Hospital de Clı´nicas de Porto Alegre, Brazil. All patients were in remission. The subjects were classified according to the staging model: 31 subjects were classified as stage I, 44 as stage II, 31 as stage III, and 23 as stage IV. Results: Patterns of pharmacological treatment differed among the four stages (p = 0.001). Monotherapy was more frequent in stage I, and two-drug combinations in stage II. Patients at stages III and IV needed three or more medications or clozapine. Impairment in functional status (Functioning Assessment Short Test [FAST] scale scores) correlated positively with the number of medications prescribed. Conclusions: This study demonstrated differences in pharmacological treatment in patients with stable BD depending on disease stage. Treatment response can change with progression of BD. Clinical guidelines could consider the staging model to guide treatment effectiveness