The neurovascular unit - concept review.

The cerebral hyperaemia is one of the fundamental mechanisms for the central nervous system homeostasis. Due also to this mechanism, oxygen and nutrients are maintained in satisfactory levels, through vasodilation and vasoconstriction. The brain hyperaemia, or coupling, is accomplished by a group of cells, closely related to each other; called neurovascular unit (NVU). The neurovascular unit is composed by neurones, astrocytes, endothelial cells of blood-brain barrier (BBB), myocytes, pericytes and extracellular matrix components. These cells, through their intimate anatomical and chemical relationship, detect the needs of neuronal supply and trigger necessary responses (vasodilation or vasoconstriction) for such demands. Here, we review the concepts of NVU, the coupling mechanisms and research strategies.

Elevated human chorionic gonadotropin levels in patients with chronic kidney disease: Case series and review of literature.

Women are often subjected to serum human chorionic gonadotropin (HCG) testing prior to diagnostic and therapeutic interventions. A positive result leads to further testing to rule out pregnancy and avoid possible fetal teratogenicity. The impact of chronic kidney disease (CKD) on HCG testing has not been studied. We report a series of 5 women out of 62 with CKD, who had a positive HCG test on routine pre-transplant screening at a single transplant center. We analyzed their case records retrospectively. Despite aggressive investigation, their elevated HCG levels remained unexplained. The positive test contributed to delays in transplantation and increased overall cost of treatment.

Extraneural metastases in medulloblastoma / Mestástases extraneurais em moduloblastoma

Medulloblastoma is the most common childhood malignant tumor of central nervous system, but it may also occur in adults. It presents high invasive growth with spreading of tumor cells into the leptomeningeal space along the neuroaxis early in the course of the disease. Extraneural metastases are rare but frequently lethal, occurring only in 1 to 5 percent of patients, and are related, in the most of cases, to the presence of ventriculoperitoneal shunt. Here we characterize the clinical profile of five cases of medulloblastoma with systemic spreading of tumor cells, also comparing them to cases already described in the literature.

O meduloblastoma é o tumor maligno mais frequente do sistema nervoso central na infância, mas também pode ocorrer em adultos. Ele apresenta crescimento altamente invasivo com disseminação de células tumorais ao longo do neuroeixo precocemente no curso da doença. Metástases extraneurais são raras mas frequentemente letais, ocorrendo apenas em 1 a 5 por cento dos pacientes, e estão relacionadas, na maioria dos casos, a presença de derivação ventriculperitoneal. Neste artigo ,apresentamos o perfil de cinco casos de meduloblastoma com disseminção sistêmica das células tumorais, comparando-os com os casos já descritos na literatura.

Effects of circular myotomy on the healing of esophageal suture anastomosis: an experimental study.

For esophageal reconstruction in newborns with esophageal atresia, esophageal reunion with an end-to-end anastomosis is the ideal procedure, although it may result in leaks and strictures due to tension on the suture line, mainly in cases with a wide gap between the ends. Circular myotomy (Livaditis' procedure) is the best method to elongate the proximal esophageal pouch and reduce anastomotic tension. This experimental investigation in dogs was undertaken to attempt to verify that circular myotomy decreases the anastomotic leak rate in newborns with wide gap esophageal atresia, and to analyze whether the technique promotes morphologic changes in the anastomotic scar. A pilot study demonstrated that it is necessary to resect more than 8 cm (40% of the total esophageal length) in order to obtain high leak rates. In the experimental project, such resection was performed in dogs divided into two groups (control group, anastomosis only, and experimental group, anastomosis plus circular myotomy in the proximal esophageal segment). The animals were killed in the 14th postoperative day, submitted to autopsy, and were evaluated as to the presence of leaks and strictures, as well as to the features (macroscopic and microscopic aspects) of the anastomosis. Leak rates were the same in both groups. Morphometric analysis revealed that in animals in the experimental group, the anastomotic scar was thinner than the control animals, and the isolated muscular manchette distal to the site of myotomy was replaced by fibrous tissue. Correspondingly, a decreased number of newly formed small vessels were noted in the experimental animals, compared to control animals. We concluded that circular myotomy does not decrease the incidence of anastomotic leaks, and it also promotes deleterious changes in anastomotic healing.