Brain ischemia alters platelet ATP diphosphohydrolase and 5'-nucleotidase activities in naive and preconditioned rats

The effects of transient forebrain ischemia, reperfusion and ischemic preconditioning on rat blood platelet ATP diphosphohydrolase and 5'-nucleotidase activities were evaluated. Adult Wistar rats were submitted to 2 or 10 min of single ischemic episodes, or to 10 min of ischemia 1 day after a 2-min ischemic episode (ischemic preconditioning) by the four-vessel occlusion method. Rats submitted to single ischemic insults were reperfused for 60 min and for 1, 2, 5, 10 and 30 days after ischemia; preconditioned rats were reperfused for 60 min 1 and 2 days after the long ischemic episode. Brain ischemia (2 or 10 min) inhibited ATP and ADP hydrolysis by platelet ATP diphosphohydrolase. On the other hand, AMP hydrolysis by 5'-nucleotidase was increased after 2, but not 10, min of ischemia. Ischemic preconditioning followed by 10 min of ischemia caused activation of both enzymes. Variable periods of reperfusion distinctly affected each experimental group. Enzyme activities returned to control levels in the 2-min group. However, the decrease in ATP diphosphohydrolase activity was maintained up to 30 days of reperfusion after 10-min ischemia. 5'-Nucleotidase activity was decreased 60 min and 1 day following 10-min ischemia; interestingly, enzymatic activity was increased after 2 and 5 days of reperfusion, and returned to control levels after 10 days. Ischemic preconditioning cancelled the effects of 10-min ischemia on the enzymatic activities. These results indicate that brain ischemia and ischemic preconditioning induce peripheral effects on ecto-enzymes from rat platelets involved in nucleotide metabolism. Thus, ATP, ADP and AMP degradation and probably the generation of adenosine in the circulation may be altered, leading to regulation of microthrombus formation since ADP aggregates platelets and adenosine is an inhibitor of platelet aggregation.

Angiotensin and baroreflex control of the circulation

There is a close association between the location of angiotensin (Ang) receptors and many important brain nuclei involved in the regulation of the cardiovascular system. The present review encompasses the physiological role of Ang II in the brainstem, particularly in relation to its influence on baroreflex control of the heart and kidney. Activation of AT1 receptors in the brainstem by fourth ventricle (4V) administration to conscious rabbits or local administration of Ang II into the rostral ventrolateral medulla (RVLM) of anesthetized rabbits acutely increases renal sympathetic nerve activity (RSNA) and RSNA baroreflex responses. Administration of the Ang antagonist Sarile into the RVLM of anesthetized rabbits blocked the effects of Ang II on the RSNA baroreflex, indicating that the RVLM is the major site of sympathoexcitatory action of Ang II given into the cerebrospinal fluid surrounding the brainstem. However, in conscious animals, blockade of endogenous Ang receptors in the brainstem by the 4V AT1 receptor antagonist losartan resulted in sympathoexcitation, suggesting an overall greater activity of endogenous Ang II within the sympathoinhibitory pathways. However, the RSNA response to airjet stress in conscious rabbits was markedly attenuated. While we found no effect of acute central Ang on heart rate baroreflexes, chronic 4V infusion inhibited the baroreflex and chronic losartan increased baroreflex gain. Thus, brainstem Ang II acutely alters sympathetic responses to specific afferent inputs thus forming part of a potentially important mechanism for the integration of autonomic response patterns. The sympathoexcitatory AT1 receptors appear to be activated during stress, surgery and anesthesia.

Serological analysis reveals circulation of influenza C viruses, Brazil

The circulation of influenza C viruses in Rio de Janeiro, Brazil, was studied when significant levels of antibodies were detected (56.7%) with hemagglutination inhibition test, used as a standard methodology for influenza virus studies.

Circulation of Eastern equine encephalitis, Western equine encephalitis, Ilhéus, Maguari and Tacaiuma viruses in equines of the Brazilian Pantanal, South America

Neutralizing antibodies to EEE (6.7%), WEE (1.2%), ILH (26.6%), MAG (28.2%) and TCM (15.7%) viruses were found in sera of 432 equines of the Brazilian Pantanal, area where undiagnosed horse deaths are frequently observed. A 4-fold rise in CF titer to EEE virus was detected in acute and convalescent sera of an encephalitis horse sacrified in 1992. Antibodies to EEE, ILH, MAG and TCM viruses were detected in horses less than 2 years old indicating recent circulation of these viruses in the Pantanal. The evidence of recent equine encephalitis associated with rising CF titer to EEE warrants a more intensive study with attempts to isolate virus from horses with clinical manifestations of encephalitis.

Studies on human anti-rabies immunization in Brazil: II - Preliminary evaluation of the 2-1-1 schedule for human pre-exposure anti-rabies immunization, employing suckling mouse brain vaccine

This study reports preliminary results of virus neutralizing antibody (VNA) titers obtained on different days in the course of human anti-rabies immunization with the 2-1-1 schedule (one dose is given in the right arm and one dose in the left arm at day 0, and one dose is apllied on days 7 and 21), recommended by WHO for post-exposure treatment with cell culture vaccines. A variant schedule (double dose on day zero and another on day 14) was also tested, both employing suckling mouse brain vaccine. A complete seroconversion rate was obtained after only 3 vaccine doses, and almost all patients (11 of 12) presented titers higher than 1.0 IU/ml. Both neutralizing response and seroconversion rates were lower in the group receiving only 3 doses, regardless of the sample collecting day. Although our results are lower than those found with cell culture vaccines, the geometry mean of VNA is fully satisfactory, overcoming the lower limit recommended by WHO of 0.5 IU/ml. The 2-1-1 schedule could be an alternative one for pre exposure immunization, shorter than the classical 3+1 regimen (one dose on days 0, 2, 4 and 30) with only three visits to the doctor, instead of four.

AN ELISA SUITABLE FOR THE DETECTION OF RABIES VIRUS ANTIBODIES IN SERUM SAMPLES FROM HUMAN VACCINATED WITH EITHER CELL-CULTURE VACCINE OR SUCKLING-MOUSE-BRAIN VACCINE

An indirect ELISA for determination of post-vaccination rabies antibody was applied. Purified rabies virus was used as antigen to coat plates, and staphylococcal protein A linked with horseradish peroxidase was used for detecting IgG antibody in human sera. Sera from humans, vaccinated with cell-culture vaccine or suckling-mouse-brain vaccine, were examined. ELISA results were compared to those obtained from the virus neutralization test. The mean and standard deviation of OD were determined for 126 negative sera (pre-vaccination) and for 73 sera from vaccinated persons showing antibody titers lower than 0.5 IU/ml. Results were defined as ELISA -positive, -negative or -doubtful. Establishment of a doubtful region reduced the number of sera otherwise classified as positive (false-positive sera). In this way, the sensitivity, specificity and agreement values were respectively 87.5%, 92.4% and 88.5%. No significant differences were observed in these values when the group vaccinated with cell-culture vaccine and the group vaccinated with suckling-mouse-brain vaccine were compared. It was shown that much of the disagreement between the values obtained by neutralization test and ELISA occurred in sera obtained at the beginning of the immunization process, and was probably due to the presence of IgM in the serum samples, detected only by the former test. This ELISA method can be used as a screening test in rabies laboratories regardless of the kind of vaccine used for immunization.

Tuberculous brain abscess in a patient with AIDS: case report and literature review

Tuberculous brain abscesses in AIDS patients are considered rare with only eight cases reported in the literature. We describe the case of a 34-year-old woman with AIDS and previous toxoplasmic encephalitis who was admitted due to headache and seizures. A brain computed tomography scan disclosed a frontal hypodense lesion with a contrast ring enhancement. Brain abscess was suspected and she underwent a lesion puncture through a trepanation. The material extracted was purulent and the acid-fast smear was markedly positive. Timely medical and surgical approaches allowed a good outcome. Tuberculous abscesses should be considered in the differential diagnosis of focal brain lesions in AIDS patients. Surgical excision or stereotactic aspiration, and antituberculous treatment are the mainstay in the management of these uncommon lesions.

Multiple brain abscesses due to Penicillium spp infection

We present a case of central nervous system (CNS) infection by a member of the Penicillium genera in a HIV-negative man in Brazil. The patient was admitted complaining of loss of visual fields and speech disturbances. CT scan revealed multiple brain abscesses. Stereothacic biopsies revealed fungal infection and amphotericin B treatment begun with initial improvement. The patient died few days later as a consequence of massive gastrointestinal bleeding due to ruptured esophageal varices. The necropsy and final microbiologic analyses disclosed infection by Penicillium sp. There are thousands of fungal species of the Penicillium genera. Systemic penicilliosis is caused by the P. marneffei and was formerly a rare disease, but now is one of the most common opportunistic infection of AIDS patients in Southeast Asia. The clinical presentation usually involves the respiratory system and the skin, besides general symptoms like fever and weight loss. Penicillium spp infection caused by species other than P. marneffei normally cause only superficial or allergic disease but rare cases of invasive disease do occur. We report the fourth case of Penicillium spp CNS infection.

Brain abscess secondary to frontal osteomyelitis

Frontal osteomyelitis is a rare complication of sinusitis. Common intracranial complications of the frontal osteomyelitis are meningitis, epidural empyema, subdural empyema and brain abscess. We described a case of frontal osteomyelitis with brain abscess caused by Staphylococcus aureus with improve after needle aspiration and antibiotics to brain abscess for eight weeks and for chronic osteomyelitis for four months.

Cryptococcus gattii fungemia: report of a case with lung and brain lesions mimicking radiological features of malignancy

A 64-year-old apparently immunocompetent white man developed lung and brain lesions of disseminated cryptococcosis. The radiologic features mimicked those of lung cancer metastatic to the central nervous system. C. gattii was recovered from cultures of bronchoalveolar lavage fluid, brain biopsy, and blood. The same fungus was recovered from pulmonary and brain specimens at autopsy. Serum and cerebrospinal fluid cryptococcal antigen tests were diagnostic in our case and should be included in the diagnostic evaluation of unexplained pulmonary and cerebral lesions. A literature search showed few reports of fungemia by this species of Cryptococcus, contrasting to C. neoformans.

Astrocytic and microglial response and histopathological changes in the brain of horses with experimental chronic Trypanosoma evansi infection

This study aimed to characterize astrocytic and microglial response in the central nervous system (CNS) of equines experimentally infected with T. evansi. The experimental group comprised males and females with various degrees of crossbreeding, ages between four and seven years. The animals were inoculated intravenously with 10(6) trypomastigotes of T. evansi originally isolated from a naturally infected dog. All equines inoculated with T. evansi were observed until they presented symptoms of CNS disturbance, characterized by motor incoordination of the pelvic limbs, which occurred 67 days after inoculation (DAI) and 124 DAI. The animals in the control group did not present any clinical symptom and were observed up to the 125th DAI. For this purpose the HE histochemical stain and the avidin biotin peroxidase method was used. Lesions in the CNS of experimentally infected horses were those of a wide spread non suppurative meningoencephalomyelitis.The severity of lesions varied in different parts of the nervous system, reflecting an irregular distribution of inflammatory vascular changes. The infiltration of mononuclear cells was associated with anisomorphic gliosis and reactive microglia was identified. The intensity of the astrocytic response in the CNS of the equines infected by T. evansi characterizes the importance of the performance of these cells in this trypanosomiasis. The characteristic gliosis observed in the animals in this experiment suggests the ability of these cells as mediators of immune response. The parasite, T. evansi, was not identified in the nervous tissues.

Circulation of antibodies against yellow fever virus in a simian population in the area of Porto Primavera Hydroelectric Plant, São Paulo, Brazil

Yellow fever (YF) is an acute viral infectious disease transmitted by mosquitoes which occurs in two distinct epidemiological cycles: sylvatic and urban. In the sylvatic cycle, the virus is maintained by monkey's infection and transovarian transmission in vectors. Surveillance of non-human primates is required for the detection of viral circulation during epizootics, and for the identification of unaffected or transition areas. An ELISA (enzyme-linked immunosorbent assay) was standardized for estimation of the prevalence of IgG antibodies against yellow fever virus in monkey sera (Alouatta caraya) from the reservoir area of Porto Primavera Hydroelectric Plant, in the state of São Paulo, Brazil. A total of 570 monkey sera samples were tested and none was reactive to antibodies against yellow fever virus. The results corroborate the epidemiology of yellow fever in the area. Even though it is considered a transition area, there were no reports to date of epizootics or yellow fever outbreaks in humans. Also, entomological investigations did not detect the presence of vectors of this arbovirus infection. ELISA proved to be fast, sensitive, an adequate assay, and an instrument for active search in the epidemiological surveillance of yellow fever allowing the implementation of prevention actions, even before the occurrence of epizootics.

Circulation of human papillomavirus (HPV) genotypes in women from Córdoba, Argentina, with squamous intraepithelial lesions

Human papillomavirus (HPV) can induce a wide spectrum of squamous intraepithelial lesions (SIL) of varying severity. The aim of the present study was to establish the frequency of HPV infection and identify the genotypes circulating in women from Córdoba, Argentina, in relation to age and cytology. A total of 186 women, between 18 and 65 years old, with antecedents of SIL, underwent a pelvic examination and had cervical cells collected for cytology and HPV DNA detection. Ninety-six samples (51.6%) were positive for HPV detection, and sixty-three (65.6%) of them showed the presence of at least one HR-HPV. Low- and high-grade SIL showed significant association in patients younger than 35 years of age. We found 18 different genotypes, with a greater presence of HR-HPV. Genotypes 16 and 6 were the most frequent. Seven (7.3%) multiple infections, 85.7% of which had at least one HR-HPV, were detected. The detection of a large number of different HPV genotypes is a warning sign. It is thus necessary to strengthen the monitoring of the circulation of high-risk genotypes, currently less prevalent in intraepithelial lesions, as a control measure for the possible impact of the implementation of vaccines against genotypes 16 and 18.

VIROLOGICAL AND SEROLOGICAL DIAGNOSIS OF RABIES IN BATS FROM AN URBAN AREA IN THE BRAZILIAN AMAZON

The outbreaks of rabies in humans transmitted by Desmodus rotundus in 2004 and 2005, in the northeast of the Brazilian State of Para, eastern Amazon basin, made this a priority area for studies on this zoonosis. Given this, the present study provides data on this phenomenon in an urban context, in order to assess the possible circulation of the classic rabies virus (RABV) among bat species in Capanema, a town in the Amazon basin. Bats were collected, in 2011, with mist nets during the wet and dry seasons. Samples of brain tissue and blood were collected for virological and serological survey, respectively. None of the 153 brain tissue samples analyzed tested positive for RABV infection, but 50.34% (95% CI: 45.67-55.01%) of the serum samples analyzed were seropositive. Artibeus planirostris was the most common species, with a high percentage of seropositive individuals (52.46%, 95% CI: 52.31 52.60%). Statistically, equal proportions of seropositive results were obtained in the rainy and dry seasons (c2 = 0.057, d.f. = 1, p = 0.88). Significantly higher proportions of males (55.96%, 95% CI: 48.96-62.96%) and adults (52.37%, 95% CI: 47.35-57.39%) were seropositive. While none of the brain tissue samples tested positive for infection, the high proportion of seropositive specimens indicates that RABV may be widespread in this urban area.