The effects of different ventilator modes on cerebral tissue oxygen saturation in patients with bidirectional superior cavopulmonary connection.

Aims and Objectives: We used near‑infrared spectroscopy to document changes in cerebral tissue oxygen saturation (SctO2) in response to ventilation mode alterations after bidirectional Glenn (BDG; superior cavopulmonary connection) procedure. We also determined whether spontaneous ventilation have a beneficial effect on hemodynamic status, lactate and SctO2 when compared with other ventilation modes. Materials and Methods: 20 consecutive patients undergoing BDG were included. We measured SctO2 during three ventilator modes (intermittent positive‑pressure ventilation [IPPV]; synchronized intermittent mandatory ventilation [SIMV]; and continuous positive airway pressure + pressure support ventilation [CPAP + PSV]). We, also, measured mean airway pressure (AWP), arterial blood gases, lactate and systolic arterial pressures (SAP). Results: There was no change in SctO2 in IPPV and SIMV modes; the SctO2 measured during CPAP + PSV and after extubation increased significantly (60.5 ± 11, 61 ± 10, 65 ± 10, 66 ± 11 respectively) (P < 0.05). The differences in the SAP measured during IPPV and SIMV modes was insignificant; the SAP increased significantly during CPAP + PSV mode and after extubation compared with IPPV and SIMV (109 ± 11, 110 ± 12, 95 ± 17, 99 ± 13 mmHg, respectively) (P < 0.05). Mean AWP did not change during IPPV and SIMV modes, mean AWP decreased significantly during CPAP + PSV mode (14 ± 4, 14 ± 3, 10 ± 1 mmHg, respectively) (P < 0.01). Conclusions: The SctO2 was higher during CPAP + PSV ventilation and after extubation compared to IPPV and SIMV modes of ventilation. The mean AWP was lower during CPAP + PSV ventilation compared to IPPV and SIMV modes of ventilation.

Paradoxical sleep deprivation: neurochemical, hormonal and behavioral alterations: evidence from 30 years of research

Sleep comprises approximately one-third of a person's lifetime, but its impact on health and medical conditions remains partially unrecognized. The prevalence of sleep disorders is increasing in modern societies, with significant repercussions on people's well-being. This article reviews past and current literature on the paradoxical sleep deprivation method as well as data on its consequences to animals, ranging from behavioral changes to alterations in the gene expression. More specifically, we highlight relevant experimental studies and our group's contribution over the last three decades.

O sono ocupa cerca de um terço de nossas vidas, entretanto seu impacto na saúde e sua influência nas condições patológicas ainda não foi completamente elucidado. A prevalência dos distúrbios de sono é cada vez maior, sobretudo nas regiões mais industrializadas, repercutindo diretamente no bem-estar da população. Este artigo tem como objetivo sintetizar e atualizar a literatura a respeito do método de privação de sono paradoxal e seu panorama de conseqüências desde comportamentais até genéticas em animais. Ainda, destacamos a contribuição e relevância dos estudos experimentais realizados por nosso grupo nas ultimas três décadas.

Advanced cerebral monitoring in neurocritical care.

New cerebral monitoring techniques allow direct measurement of brain oxygenation and metabolism. Investigation using these new tools has provided additional insight into the understanding of the pathophysiology of acute brain injury and suggested new ways to guide management of secondary brain injury. Studies of focal brain tissue oxygen monitoring have suggested ischemic thresholds in focal regions of brain injury and demonstrated the interrelationship between brain tissue oxygen tension (P bt O 2 ) and other cerebral physiologic and metabolic parameters. Jugular venous oxygen saturation (SjVO 2 ) monitoring may evaluate global brain oxygen delivery and consumption, providing thresholds for detecting brain hypoperfusion and hyperperfusion. Furthermore, critically low values of P bt O 2 and SjVO 2 have also been predictive of mortality and worsened functional outcome, especially after head trauma. Cerebral microdialysis measures the concentrations of extracellular metabolites which may be relevant to cerebral metabolism or ischemia in focal areas of injury. Cerebral blood flow may be measured in the neurointensive care unit using continuous methods such as thermal diffusion and laser Doppler flowmetry. Initial studies have also attempted to correlate findings from advanced neuromonitoring with neuroimaging using dynamic perfusion computed tomography, positron emission tomography, and Xenon computed tomography. Additionally, new methods of data acquisition, storage, and analysis are being developed to address the increasing burden of patient data from neuromonitoring. Advanced informatics techniques such as hierarchical data clustering, generalized linear models, and heat map dendrograms are now being applied to multivariable patient data in order to better develop physiologic patient profiles to improve diagnosis and treatment.

Prehospital care of head injured patients.

Resuscitation of head injured patients at the accident site is paramount in minimizing morbidity and mortality. This can be achieved through prehospital care which is nonexistent in our country. This review is a step forward, so that we can formulate guidelines in this regard.

Physiologic effects of maternal separation on rat brain neurochemistry: comparative study

Exposure to maternal separation in early life is associated with alteration in the neuroendocrine and neurotransmitter system which may be associated with risk of psychiatric disorders development at adulthood. The aim of this study was to [i] assess levels of monoamines [dopamine, nor-epinephrine, epinephrine and serotonin] in rat pup's brain following repeated maternal separation [RMS] and maternal deprivation [MD]. [ii] Assess brain corticosterone and oxytocin level following both RMS and MD. This study was carried out on 50 male rat pups divided into 3 experimental groups; Group I: 20 rats subjected to 3 h of repeated maternal separation for 14 days; Group II: 20 rats subjected to 24 h of maternal deprivation; Group III: 10 rats served as control group. At the end of the experimental period, all rats were sacrificed and their brains were rapidly removed and dissected for estimation of monoamines, corticosterone and oxytocin. Brain corticosterone level showed marked increase after both separation procedures, however, MD was associated with marked increase. RMS was associated with higher level of epinephrine, norepinephrine, dopamine and serotonin. Dopamine and serotonin levels however, were reduced after MD. Oxytocin level showed marked reduction after MD and RMS. The current work provided some neurobiological evidence supporting the determinant role of mother-infant relationship in the development of psychopathology. Maternal separation leads to profound alterations in the central neurotransmitter system and therefore is associated with increased risk of psychiatric disorders as depression and anxiety. Moreover, maternal separation has impact on the corticosterone and oxytocin release in the brain. Different separation procedures however, can influence the consequences of MS

Da herança à localização cerebral: sobre o determinismo biológico de condutas indesejadas / From heritage to cerebral localization: on the biological determinism of undesired conducts

Analisamos os argumentos utilizados, em dois momentos diferentes do século XX, para justificar o recurso a explicações biológicas de condutas consideradas como socialmente indesejadas. Referimo-nos, inicialmente, aos estudos realizados pelos higienistas de início do século, cujas explicações estavam centradas no caráter orgânico e inato dos desvios, para continuar logo com os recentes estudos da neurociência que se propõem a localizar as condutas nas sinapses inadequadas e nas explicações referidas a deficiências químicas do cérebro.

The article analyzes the arguments used in two distinct moments of the 20th century, to justify the use of biological explanations for conducts considered as socially undesirable. Firstly we refer to studies of hygienists in the early century, whose explanation were centered on the organic and innate character of deviations, then we analyze the recent studies in the neurosciences which try to locate these conducts in inadequate synapses and in explanations related to chemical cerebral deficiencies.

Brain tumor and role of beta-carotene, a-tocopherol, superoxide dismutase and glutathione peroxidase.

The erythrocyte levels of the antioxidant enzymes SOD and GPx, and serum levels of antioxidants vitamins beta-carotene and beta-tocopherol were estimated in various types of brain tumors, and were compared with the levels in controls. Statistically significant (P<.001) diminished levels of beta-carotene, beta-tocopherol, SOD and GPx, were observed in all the brain tumor patients as compared to controls. Malignant tumor also showed a relative decrease in antioxidant levels as compared to benign tumors. Comparison of histopathological sections of brain tumors also suggested a inverse relationship between antioxidant level and grades of malignancy. Marked decrease in antioxidant levels may have a role in genesis of considerable oxidative stress in brain tumors. Furthermore, the degree of decline in antioxidant levels may indicate severity of malignancy in brain tumors.

Change in tissue thromboplastin content of brain following trauma.

BACKGROUND: Tissue thromboplastin (TTP) is an integral membrane protein contributing to coagulopathy after trauma of brain, which is a rich source of TTP. AIMS: A study was undertaken to establish the TTP content of various areas of normal brain and estimate the changes in TTP activity of brain in response to varying degrees of trauma. MATERIALS AND METHODS: Samples from different areas of brain of ten cadavers were used as controls and they were compared with contused brain tissue obtained after surgery in 25 head injury (HI) patients of varying severity. RESULTS: In the study group, the TTP activity of the frontal, parietal, and temporal lobes after HI was significantly raised in contrast to that of the control group. The TTP activity was also significantly higher in the severe HI patients than those having moderate HI. The mode of injury and the time lapse after HI had no significant bearing on the TTP activity. Subjects above 40 years of age demonstrated a higher mean TTP activity after HI, though it was not statistically significant. CONCLUSION: The study provides quantitative data on TTP activity of normal brain and highlights the role of TTP in coagulopathy following HI through its increased activity after HI, more so in the severe HI group.

O eixo hipotálamo-pituitária-adrenal, a função dos receptores de glicocorticóides e sua importância na depressão / The Hypothalamic Pituitary Adrenal axis, Glucocorticoid receptor function and relevance to depression

OBJETIVO: As mudanças no eixo hipotálamo-pituitária-adrenal (HPA) são características da depressão. Devido aos efeitos dos glicocorticóides serem mediados por receptores intracelulares, como os receptores de glicocorticóides (RGs), inúmeros estudos examinaram o número e/ou função dos RGs em pacientes com depressão. MÉTODOS: Os autores fazem uma revisão das evidências científicas dos estudos que têm consistentemente demonstrado que a função dos RGs está prejudicada na depressão maior, em conseqüência da redução da resposta do eixo HPA ao feedback negativo mediado pelos RGs e a um aumento na produção e secreção de HLC em várias regiões cerebrais, sugerindo que esses mecanismos estão envolvidos na etiologia da depressão e no tratamento antidepressivo. RESULTADOS: Esta revisão faz um resumo da literatura atual sobre RG na depressão e sobre o impacto dos antidepressivos nos RGs em estudos clínicos e pré-clínicos, e dá suporte ao conceito de que a sinalização deficiente dos RGs é parte fundamental na fisiopatogenia da depressão, na ausência de evidências claras de redução na expressão dos RGs. Embora os efeitos dos antidepressivos nos hormônios glicocorticóides e seus receptores sejam relevantes para a ação terapêutica dessas drogas, os mecanismos moleculares subjacentes a esses efeitos ainda não estão esclarecidos. Estudos indicam que os antidepressivos têm efeitos diretos nos RGs, levando a uma melhora da função e a um aumento da expressão dos RGs. Nós propomos que, em humanos, os antidepressivos podem inibir os transportadores de esteróides localizados na barreira hemato-liquórica e nos neurônios, como o complexo de resistência a múltiplas drogas glicoproteína-p ("multidrug resistance p-glycoprotein"), e podem aumentar o acesso do cortisol ao cérebro e o feedback negativo mediado por glicocorticoides no eixo HPA. CONCLUSÃO: O aumento da ação do cortisol no cérebro pode ser uma abordagem eficaz para maximizar os efeitos terapêuticos dos antidepressivos. Hipóteses referentes aos mecanismos destes receptores envolvem compostos não esteróides que regulam a função dos RGs via segundos mensageiros. A pesquisa nesta área trará novos entendimentos à fisiopatologia e ao tratamento dos transtornos afetivos, em especial na depressão.

Human brain: biochemical lateralization in normal subjects.

Chemical asymmetries in normal human brain were studied using the non-invasive technique of volume localized proton magnetic resonance spectroscopy (MRS). The technique of STEAM was used to acquire water-suppressed proton spectra from 8 ml voxels placed in bilaterally symmetrical positions in the two hemispheres of the brain. One hundred and sixty eight right-handed male volunteers were studied for six different regions in the brain (n=28, for each region). Parietal, occipital, temporal, frontal, thalamus and cerebellum regions were studied. The focus was on metabolites such as N-acetyl aspartate (NAA), creatine/phosphocreatine (Cr/PCr) and choline (Cho) containing compounds. Ratios of the peak areas were calculated for them. Quantitation of the metabolites were carried for data on 18 volunteers. Significant interhemispheric differences in the distribution of metabolites were observed for all the regions studied. There were statistically significant differences on right and left side for the metabolite ratios in all the regions studied. The study has shown the existence of significant lateralization in the distribution of proton MR visible metabolites for all the regions studied.

Hipóteses fisiopatológicas e considerações terapêuticas da acatisia induzida por antipsicóticos / Pathophysiological hypothesis and therapeutic considerations of neurolepticðinduced akathisia

A fisiopatologia da acatisia induzida por antipsicóticos não está totalmente compreendida. Muitas hipóteses propostas têm demonstrado o possível envolvimento de diversas vias neuronais do sistema nervoso central, incluindo os sistemas noradrenérgico, dopaminérgico, serotoninérgico, colinérgico e gabaérgico. Os autores apresentam hipóteses fisiopatológicas e considerações terapêuticas da acatisia induzida por antipsicóticos

Identification and estimation of endogenous digoxin in biological fluids and tissues by TLC and HPLC.

A procedure for estimation of digoxin in biological samples after adding a known quantity of digoxin followed by extraction, separation by TLC and HPLC is described. The identity of digoxin thus extracted from rat brain has been established by reaction with digoxin antibody and by its inhibition of Na(+)-K+ ATPase activity. The method could be a better substitute to the routine radioimmunoassay as interfering substances are removed by TLC and HPLC.

Background and paroxystic activities on AIDS patients' EEG

The HIV is responsible for important metabolic and structural alterations of the brain. This affected brain must react to continuous systemic metabolic fluctuations. We search for possibly resulting cerebral electric disturbance that could be found by EEG exploration. Sixty-three AIDS patients ranked as CDC group IV had their EEG background rhythm measured, and were appointed to mutually exclusiding groups delimited by medians'values of urea (24 mg/dl) and creatinine (0.9 mg/dl) seric concentrations. These groups were independently formed for each of the parameters utilized, and each data pair generated therefrom were compared between themselves to verify whether there were differences in background rhythm and the occurrence of paroxysmal activity. Background rhythm and paroxysmal activities have not statistically differed between the group whose creatinine values were lower than 0.9 mg/dl and the group whose creatinine values were equal or higher than 0.9 mg/dl. Background rhythm has not statistically differed between the group whose ures values were <24 mg/dl and the group whose urea values were =24 mg/dl; contrariwise, the occurrence of paroxysmal activities in these groups has significatively differed, being higher in the patient group whose otherwise normal urea values exceeded 24 mg/dl (0=0.02).

Immunohistochemical study of the expression of human groEL-stress protein in human nervous tissue.

Monoclonal antibody (ML-30) directed against 65 kDa stress protein of mycobacteria, is shown to identify human cellular protein homologous with the groEL heat shock protein in many prokaryotes. Immunohistochemical survey of nervous tissue, both central and peripheral, from patients dying of various inflammatory, degenerative and neoplastic conditions and from experimental animals, using this antibody showed punctate granular staining of the cells to a variable degree. The astrocytes showed strong immunolabelling. The normal neurons and oligodendroglia stained variably, while abnormal neurons were darkly labelled. Ependymal cells showed apical granular positivity. The ubiquitinated inclusion bodies in amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease were not recognised by the ML-30 antibody. In diseased and stressed nervous tissue from experimental animals, the expression of the ML-30 recognisable stress protein was variable. The epitope recognised by ML-30 was found stable in postmortem tissues collected up to 36 h after death and processed for paraffin sectioning, after fixation in formalin for many years. Enhanced expression of the human groEL stress protein homologue in mammalian nervous tissue following various forms of stress may play a role in modulating the extent of tissue damage by autoimmune mechanism because of its high immunogenic nature and constitutive presence in the cells.

Spectrophotometric titration of phenoxyl groups of sheep brain tubulin.

Spectrophotometric titration of phenoxyl group of sheep brain tubulin carried out in 6M guanidine hydrochloride indicated 36 tyrosine residues per dimer of tubulin. A plot of log alpha/(1-alpha) versus pH showed that 26 residues titrated with apparent pK of 10.4 and 10 residues titrated with apparent pK of 11.0. The high pK value of tyrosine could be attributed to the possibility that the molecules containing tyrosine residues were not completely utilised as these residues could have been partially shielded from the solvent. Alternatively, they could have proximal negative charges.

A molecular weight study of the rat brain delta opioid receptor.

The molecular weight of the rat brain delta opioid receptor, studied with antiidiotypic antibodies to anti-leucine enkephalin that mimic leucine enkephalin in binding to the receptor, was examined by molecular sieving and Western Blots under nondenaturing, denaturing and reducing conditions. The receptor appeared to be 55-65 kDa, which on solubilization may exist in equilibrium with receptor oligomers of 130-150 kDa and aggregates of > 200 kDa. These forms may also represent aggregation due to solubilization. A 38-43 kDa molecule was considered a minor form of the receptor in the brain.