Effects of intranasal guanosine administration on brain function in a rat model of ischemic stroke.

Ischemic stroke is a major cause of morbidity and mortality worldwide and only few affected patients are able to receive treatment, especially in developing countries. Detailed pathophysiology of brain ischemia has been extensively studied in order to discover new treatments with a broad therapeutic window and that are accessible to patients worldwide. The nucleoside guanosine (Guo) has been shown to have neuroprotective effects in animal models of brain diseases, including ischemic stroke. In a rat model of focal permanent ischemia, systemic administration of Guo was effective only when administered immediately after stroke induction. In contrast, intranasal administration of Guo (In-Guo) was effective even when the first administration was 3 h after stroke induction. In order to validate the neuroprotective effect in this larger time window and to investigate In-Guo neuroprotection under global brain dysfunction induced by ischemia, we used the model of thermocoagulation of pial vessels in Wistar rats. In our study, we have found that In-Guo administered 3 h after stroke was capable of preventing ischemia-induced dysfunction, such as bilateral suppression and synchronicity of brain oscillations and ipsilateral cell death signaling, and increased permeability of the blood-brain barrier. In addition, In-Guo had a long-lasting effect on preventing ischemia-induced motor impairment. Our data reinforce In-Guo administration as a potential new treatment for brain ischemia with a more suitable therapeutic window.

Experimental use of new absorbable tracheal stent.

BACKGROUND/PURPOSE: Silicone and metallic stents are not effective in children with tracheobronchial stenosis or tracheomalacia. Herein, we aimed to evaluate the clinical manifestations and histological reaction of rabbit trachea to the presence of a new poly(lactic-co-glycolic acid) with polyisoprene (PLGA/PI) polymer absorbable stent. METHODS: Fourteen adult white rabbits (weight, 3.0-3.5kg) were randomly assigned to three groups: Group I (n=6): PLGA/PI spiral stent; Group II (n=6): PLGA/PI fragment; and Group III (n=2): controls. After a longitudinal incision on three cervical tracheal rings, the stents and fragments were inserted into the trachea and fixed onto the lateral wall with nonabsorbable sutures. RESULTS: The stented group showed significantly more stridor at rest (p=0.0041), agitation (p=0.014), and use of accessory muscles (p=0.0002) and required more emergency endoscopies than the fragment group. Further, it showed significantly more remarkable histological inflammatory damage than the fragment and control groups (p=0.002). CONCLUSIONS: The new PLGA/PI polymeric stent implanted into the trachea of rabbits caused more clinical manifestations and histologically verified inflammatory reaction than the PLGA/PI polymeric fragment. Future studies should be aimed at reducing the stent-wall thickness.

Enzyme replacement therapy started at birth improves outcome in difficult-to-treat organs in mucopolysaccharidosis I mice.

Since we previously observed that in patients with mucopolysaccharidosis (MPS) the storage of undegraded glycosaminoglycans (GAG) occurs from birth, in the present study we aimed to compare normal, untreated MPS I mice (knockout for alpha-l-iduronidase-IDUA), and MPS I mice treated with enzyme replacement therapy (ERT, Laronidase, 1.2mg/kg every 2 weeks) started from birth (ERT-neo) or from 2 months of age (ERT-ad). All mice were sacrificed at 6 months. Both treatments were equally effective in normalizing GAG levels in the viscera but had no detectable effect on the joint. Heart function was also improved with both treatments. On the other hand, mice treated from birth presented better outcomes in the difficult-to-treat aortas and heart valves. Surprisingly, both groups had improvements in behavior tests, and normalization of GAG levels in the brain and IDUA injection resulted in detectable levels of enzyme in the brain tissue 1h after administration. ERT-ad mice developed significantly more anti-IDUA-IgG antibodies, and mice that didn't develop antibodies had better performances in behavior tests, indicating that development of antibodies may reduce enzyme bioavailability. Our results suggest that ERT started from birth leads to better outcomes in the aorta and heart valves, as well as a reduction in antibody levels. Some poor vascularized organs, such as the joints, had partial or no benefit and ancillary therapies might be needed for patients. The results presented here support the idea that ERT started from birth leads to better treatment outcomes and should be considered whenever possible, a observation that gains relevance as newborn screening programs are being considered for MPS and other treatable lysosomal storage disorders.

Impairment of short term memory in rats with hepatic encephalopathy due to bile duct ligation.

Hepatic encephalopathy (HE) arises from acute or chronic liver diseases and leads to cognitive deficits. Different animal models for the study of HE have demonstrated learning and memory impairment and a number of neurotransmitter systems have been proposed to be involved in this. Recently, it was described that bile duct-ligated (BDL) rats exhibited altered spatio-temporal locomotor and exploratory activities and biosynthesis of neurotransmitter GABA in brain cortices. Therefore, the aim of this study was to evaluate cognition in the same animal model. Male adult Wistar rats underwent common bile duct ligation (BDL rats) or manipulation of common bile duct without ligation (control rats). Six weeks after surgery, control and BDL rats underwent object recognition behavioral task. The BDL rats developed chronic liver failure and exhibited a decreased discrimination index for short term memory (STM) when compared to the control group. There was no difference in long term memory (LTM) as well as in total time of exploration in the training, STM and LTM sessions between the BDL and control rats. Therefore, the BDL rats demonstrated impaired STM for recognition memory, which was not due to decreased exploration.

Barrier methods used to prevent pelvic adhesions in videolaparoscopy: experimental study in female rabbits.

BACKGROUND: This study was designed to evaluate the effectiveness of barrier methods to prevent adhesions in videolaparoscopy, comparing the use of Surgicel(®) and Interceed(®) with the control group. METHODS: We performed a controlled, randomized study in healthy adult female rabbits Oryctolagus cuniculu, inducing adhesions in the abdominal wall by resection of a peritoneal fragment and cauterization. In the control group, surgery was performed, and the other group was randomized to the use of the barrier method. After 21 days, videolaparoscopy was repeated, and the presence or absence of adhesions and their score were verified by performing biopsies of the surgical site in all groups. RESULTS: No statistical differences were found in the results on adhesion formation and adhesions score among the three groups. In the control group, there were 54.5% cases of adhesion formation; the median score of adhesions was 6 (range, 3-10). In the Surgicel(®) group, there were 45.5% cases of adhesion formation; median score of adhesions was 6 (range, 4-10). In the Interceed(®) group, there were 45.5% cases of adhesion formation; median score of adhesions was 5 (range, 3-11). CONCLUSIONS: No difference was found using barrier methods, Surgicel(®), and Interceed(®) for preventing adhesion formation in videolaparoscopy.