Neuroprotective effects of guanosine administration on behavioral, brain activity, neurochemical and redox parameters in a rat model of chronic hepatic encephalopathy.

It is well known that glutamatergic excitotoxicity and oxidative stress are implicated in the pathogenesis of hepatic encephalopathy (HE). The nucleoside guanosine exerts neuroprotective effects through the antagonism against glutamate neurotoxicity and antioxidant properties. In this study, we evaluated the neuroprotective effect of guanosine in an animal model of chronic HE. Rats underwent bile duct ligation (BDL) and 2 weeks later they were treated with i.p. injection of guanosine 7.5 mg/kg once a day for 1-week. We evaluated the effects of guanosine in HE studying several aspects: a) animal behavior using open field and Y-maze tasks; b) brain rhythm changes in electroencephalogram (EEG) recordings; c) purines and glutamate levels in the cerebral spinal fluid (CSF); and d) oxidative stress parameters in the brain. BDL rats presented increased levels of glutamate, purines and metabolites in the CSF, as well as increased oxidative damage. Guanosine was able not only to prevent these effects but also to attenuate the behavioral and EEG impairment induced by BDL. Our study shows the neuroprotective effects of systemic administration of guanosine in a rat model of HE and highlights the involvement of purinergic system in the physiopathology of this disease.

Evaluation of a commercial ligase chain reaction assay for the diagnosis of pulmonary and extra-pulmonary tuberculosis.

SETTING: Egas Moniz Hospital, Lisbon, Portugal. OBJECTIVE: To evaluate the Ligase Chain Reaction (LCx) Mycobacterium tuberculosis Assay for the direct detection of M. tuberculosis complex in respiratory specimens after smear observation, and its suitability for non-respiratory clinical specimens. DESIGN: Analysis of 156 specimens collected from 123 patients with pulmonary tuberculosis and/or extrapulmonary involvement. RESULTS: Among 93 pulmonary secretions and 63 extra-pulmonary samples and after resolution of discrepancies based on clinical and laboratory findings, two pulmonary samples from a patient with a diagnosis of sarcoidosis, four samples of cerebrospinal and one of seminal fluid were considered as false positives. Two tissue biopsy samples, one pericardial effusion and one pulmonary secretion from patients strongly suspected of having tuberculosis were considered as false negatives for the assay, without inhibition of amplification. All specimens yielding M. avium on culture were LCx negative. CONCLUSION: The LCx Mycobacterium tuberculosis Assay was found to be useful for the rapid identification of M. tuberculosis complex in all types of specimens. It revealed a high specificity both in pulmonary and extrapulmonary products, and a sensitivity of 97% for the pulmonary secretions and of 75% for the extra-pulmonary specimens, independently of the bacilloscopy results.

Outbreak of multiple drug-resistant tuberculosis in Lisbon: detection by restriction fragment length polymorphism analysis.

SETTING: Multidrug-resistant tuberculosis (MDR-TB) mainly among human immunodeficiency virus (HIV) seropositive patients in Lisbon hospitals in 1996-1997. OBJECTIVE: Detection of transmission of MDR-TB strains and epidemic outbreaks in several hospital units in the city of Lisbon, including a prison hospital. DESIGN: Use of restriction fragment length polymorphism (RFLP) to fingerprint isolates of Mycobacterium tuberculosis resistant to isoniazid, rifampicin, and one other drug. RESULTS: A total of 43 MDR-TB strains were typed. Sixty-seven per cent of the patients were HIV positive, 12% were HIV negative, and the remainder had unknown HIV status. About 88% of the isolates were grouped in three genetically similar clusters, suggesting possible recent transmission. A predominant cluster (cluster A), corresponding to 72% of the cases, was found, 45% of which came from the prison hospital. Strains from this cluster were resistant to isoniazid, rifampicin, streptomycin, and sometimes ethambutol. A retrospective epidemiological investigation was conducted with respect to all patients in cluster A, and epidemiological links were established between them. CONCLUSION: Our results suggest recent transmission of MDR-TB, mainly in HIV-positive patients, in Lisbon hospitals. Moreover, the predominant MDR-TB clustered strains were not confined to HIV-infected individuals, as they were also isolated in some immunocompetent patients.

Antiepileptogenic properties of phenobarbital: behavior and neurochemical analysis.

Chronic in vivo models of epilepsy provide a suitable strategy for quantifying epileptogenesis, as well as investigating neurochemical changes associated with neuronal plasticity that leads to seizuring conditions. The aim of this paper was to investigate antiepileptogenic properties of phenobarbital, focusing on the neurochemical changes associated with repeated seizures induced by low convulsive dose of pentylenetetrazol (PTZ) (60 mg/kg, sc) in mice. Phenobarbital (10 and 30 mg/kg, ip) significantly diminished the severity of seizures induced by PTZ. Repeated PTZ administration was associated with an increase in [3H]glutamate binding (B(max) 196.6+/-10.2 pmol/mgxcontrol B(max) 137.7+/-17.0 pmol/mg). Regarding NMDA receptors, repeated PTZ administration was likewise associated with an increase in [3H]MK-801 binding (0.55+/-0.02 pmol/mgxcontrol 0.32+/-0.01 pmol/mg). In addition, phenobarbital (10 mg/kg) prevented the increase in [3H]glutamate binding (B(max) 133.7+/-11.4 pmol/mg), as well as in [3H]MK-801 binding (phenobarbital 10 and 30 mg/kg, 0.33+/-0.01 and 0.34+/-0.01 pmol/mg, respectively). This study reveals an interesting capability of phenobarbital in interfering with the establishment of both the behavioral expression and associated neurochemical changes induced by the repeated administration of low convulsive dose of PTZ, which may be important in the context of preventing epileptogenesis.

A ten-year survey of Tinea pedis in the central region of the Rio Grande do Sul, Brazil.

Tinea pedis in the most common type of dermatophytosis, but can mimic many cutaneous diseases and tend to be chronic. We present a study of the frequency, epidemiology and clinical aspects of tinea pedis in the central region of Rio Grande do Sul during the period 1988-1997.

[Epidemiology of sporotrichosis in the central region of Rio Grande do Sul]. / Epidemiologia da esporotricose na região central do Rio Grande do Sul.

Thirty-one cases of sporotrichosis diagnosed in the central region of Rio Grande do Sul from 1988 to 1997 were studied. Clinical data were compared with a study concerning three past decades, clearly showing a decrease in the incidence of the mycosis, and an alteration in the profile of the infection, with a decrease of sporotrichosis in rural patients, children, women and farmers. In the past decade the mycosis was most frequent among urban adults with different professions, with the onset of the disease being associated with rural leisure activities such as fishing and hunting.

Chronic sulforaphane oral treatment accentuates blood glucose impairment and may affect GLUT3 expression in the cerebral cortex and hypothalamus of rats fed with a highly palatable diet.

Obesity and insulin resistance are the key factors underlying the etiology of major health problems such as hypertension, diabetes and stroke. These important health issues lead researchers to investigate new approaches to prevent and treat obesity and insulin resistance. Good candidates are the phytochemical compounds that have been extensively studied in the field. Therefore, the aim of this study was to test whether sulforaphane (SFN, 1 mg kg⁻¹, 4 months treatment), a potent inducer of antioxidant enzymes present in cruciferous vegetables, had some beneficial effects on obesity and insulin resistance induced by a highly palatable (HP) diet in male Wistar rats. Glucose tolerance, serum and hepatic lipid levels, lipid profile, ALT, AST, urea and creatinine, GLUT1 and GLUT3 levels in the cerebral cortex, hippocampus and hypothalamus were analyzed. Glucose tolerance was lower in the HP diet groups, especially in the HP group treated with SFN. Except for the liver triacylglycerols, no differences were found in serum lipids, hepatic and kidney markers of the HP diet groups. Although expression of GLUT1 was similar between groups for all three brain structures analyzed, expression of GLUT3 in the cortex and hypothalamus had a tendency to decrease in the HP diet group treated with SFN. In conclusion, SFN at the specific dose was able to accentuate glucose intolerance and may affect GLUT3 expression in the cerebral cortex and hypothalamus.

Tuberculosis drug-resistance in Lisbon, Portugal: a 6-year overview.

Multidrug-resistance and extensive drug-resistance pose a serious threat to tuberculosis management in Portugal. The country has high TB incidence rates in comparison with other European Union countries, with the Lisbon Health Region being one of the most affected. In the present study we have analysed a convenience sample of 3025 Mycobacterium tuberculosis clinical isolates, recovered over a 6-year period (2001-2006) in the Lisbon Health Region, regarding drug-resistance both to first-line and second-line drugs. Moreover, 100 of these isolates were also genotyped by 12-loci Mycobacterial Interspersed Repetitive Unit - Variable Number of Tandem Repeats (MIRU-VNTR) analysis. We have compared each year and observed the existence of 22 different resistance profiles, with MDR-TB rates ranging between 9.9% and 15.2% and XDR-TB rates, relative to the number of MDR-TB isolates, between 44.3% and 66.1% (excluding 1 year here considered as an outlier). A steady increase in the fraction of MDR-TB isolates resistant to all first-line drugs was also noticed. The genotyping analysis of MDR-TB isolates revealed six clusters, of which three (Lisboa3, Lisboa4 and Q1) were related to XDR-TB. Our results show that active transmission of MDR- and XDR-TB is taking place and that the high prevalence of observed XDR-TB is due to the continued transmission of particular genetic clusters. Enforcement of the implementation of genotyping in diagnostic routines would lead to early detection of resistant cases.

(-)-Linalool, a naturally occurring monoterpene compound, impairs memory acquisition in the object recognition task, inhibitory avoidance test and habituation to a novel environment in rats.

It is known that (-)-linalool is a competitive antagonist of NMDA receptors, which play a key role in the learning and memory processes; however, only a few studies have reported a possible interference of (-)-linalool in memory. The purpose of this study was to investigate the (-)-linalool effects on acquisition of short- and long-term memories through the objects recognition task, inhibitory avoidance test and habituation to a novel environment. Furthermore, the open field test was used to investigate the interference of (-)-linalool in motivation, locomotion and exploration by animals. Wistar male adult rats received an intraperitoneal injection (i.p.) of saline (NaCl 0.9%), tween 5% or (-)-linalool (50 or 100 mg/kg) before training in the tasks; MK-801 (0.1 mg/kg), a glutamate antagonist, was used as positive control. Short-term (STM) and long-term (LTM) memories were tested 1.5 and 24 h after training, respectively, in the inhibitory avoidance and recognition objects. The results suggested that (-)-linalool (as 50- and 100-mg/kg doses) impaired LTM acquisition, but not STM acquisition, in the object recognition task. In the inhibitory avoidance test, animals receiving linalool (both doses) showed impairment in acquisition of both memories measured. In the open field test, the animals that received (-)-linalool showed no significant difference in the crossings and latency to start the locomotion in any of the doses tested, although (-)-linalool 100 mg/kg reduced rearing behavior. When re-exposed to open field 24 h after training, the rats that received (-)-linalool 100mg/kg showed no habituation. Taken together, these data suggested that (-)-linalool was able to impair the acquisition of memory in rats, which can be associated to (-)-linalool antagonist capacity as regards NMDA glutamatergic receptors, since other glutamate antagonists also seem to affect memory.

Molecular surveillance of Neisseria meningitidis capsular switching in Portugal, 2002-2006.

Neisseria meningitidis capsular switching has been reported in several countries. In order to establish the genetic relationship within group B and C strains expressing subtypes 2a or 2b, and to evaluate whether C to B capsular switching occurred in Portugal, 64 meningococci (56 serogroup C and 8 serogroup B) isolated from invasive meningococcal disease were typed using molecular methods. The studied phenotypes, 2b:P1.5,2 and 2a:P1.5-1,10-8, were the most frequent among serogroup C, but were uncommon among serogroup B strains. The multi-locus sequence typing (MLST) allelic profile and the pulsed-field gel electrophoresis (PFGE) fingerprints showed that seven serogroup B strains were genotypically identical to C strains, suggesting that capsular switching occurred. Active laboratory surveillance to find evidence of capsule switching is a now priority as MenC was introduced in the Portuguese vaccination schedule in January 2006.

Streptococcus agalactiae serotype Ib as an agent of meningitis in two adult nonpregnant women.

Two temporally and geographically clustered cases of meningitis caused by Streptococcus agalactiae expressing the infrequent Ib serotype are reported. Characterization by pulsed-field gel electrophoresis and multilocus sequence typing revealed that the isolates were identical and represented the widely distributed ST10/ST8 lineage associated with serotype Ib.

Anticonvulsant properties of linalool in glutamate-related seizure models.

In order to investigate the pharmacodynamic basis of the previously-established anticonvulsant properties of linalool, we examined the effects of this compound on behavioral and neurochemical aspects of glutamate expression in experimental seizure models. Specifically, linalool effects were investigated to determine its inhibition of (i) L-[3H]glutamate binding at CNS (central nervous system membranes), (ii) N-methyl-D-aspartate (NMDA)-induced convulsions, (iii) quinolinic acid (QUIN)-induced convulsions, and the behavioral and neurochemical correlates of PTZ-kindling. The data indicate that linalool modulates glutamate activation expression in vitro (competitive antagonism of L-[3H]glutamate binding) and in vivo (delayed NMDA convulsions and blockage of QUIN convulsions). Linalool partially inhibited and significantly delayed the behavioral expression of PTZ-kindling, but did not modify the PTZ-kindling-induced increase in L-[3H]glutamate binding.

Effects of linalool on [(3)H]MK801 and [(3)H] muscimol binding in mouse cortical membranes.

Linalool is a monoterpene compound reported to be a major component of essential oils of several aromatic species. Several linalool-producing species are used in traditional medical systems for sedative purposes, including the interruption and prevention of seizures. Previous studies in mice revealed that linalool modulates glutamatergic (competitive antagonism of L-[(3)H]glutamate binding, delayed intraperitoneal NMDA-induced convulsions and blockade of intracerebroventricular Quin-induced convulsions) and GABAergic transmission (protection against pentylenetetrazol and picrotoxin-induced convulsions). To further clarify the anticonvulsive mechanisms of linalool, we studied the effects of linalool on binding of [(3)H]MK801 (NMDA antagonist) and [(3)H]muscimol (GABA(A) agonist) to mouse cortical membranes. Linalool showed a dose dependent non-competitive inhibition of [(3)H]MK801 binding (IC(50) = 2.97 mM) but no effect on [(3)H]muscimol binding. The data suggest that the anticonvulsant mode of action of linalool includes a direct interaction with the NMDA receptor complex. The data do not, however, support a direct interaction of linalool with GABA(A) receptors, although changes in GABA-mediated neuronal inhibition or effects on GABA release and uptake cannot be ruled out.

Effects of linalool on glutamate release and uptake in mouse cortical synaptosomes.

Linalool, a monoterpene compound prevalent in essential oil of plant species traditionally used as sedatives, has been characterized as anticonvulsant in several experimental models. Linalool inhibits the binding of [3H]glutamate and [3H]dizocilpine to brain cortical membranes, indicating a participation of the glutamatergic transmission its mechanism of action. In this study, we investigated the effects of linalool on [3H]glutamate release (basal and potassium-stimulated) and [3H]glutamate uptake in mice cortical synaptosomes. Linalool significantly reduced potassium-stimulated glutamate release as well as glutamate uptake, not interfering with basal glutamate release. The data indicates that linalool may interfere with several relevant elements of the glutamatergic transmission, including detriment of the K+-stimulated glutamate release.

IgG subclass distribution of antibody responses to protein and polysaccharide mycobacterial antigens in leprosy and tuberculosis patients.

Immunoenzymatic assays were developed for the measurement of antibodies against mycobacterial lipoarabinomannan (LAM), a cell-free proteic extract (CFX) of Mycobacterium leprae, and the 38-kD protein antigen of M. tuberculosis. Sera from 108 leprosy patients, belonging to all clinical-immunological forms of the spectrum, and 81 patients with localized or disseminated tuberculosis (TB) were tested for antibodies of the four IgG subclasses. Standard calibration curves were used to allow comparisons between results of different isotypes and specificities. Mean concentrations of total IgG antibodies were higher in the overall leprosy population than in TB patients. In leprosy, levels of anti-CFX increased from tuberculoid toward lepromatous forms, with a clear switch from IgG1 to IgG2 subclass predominance. A similar IgG1 to IgG2 conversion was observed in anti-LAM antibodies, although total levels of anti-LAM were similar in patients with tuberculoid and lepromatous forms. In TB, antibodies against polysaccharide and protein antigens were both predominantly of IgG1 subclass, whatever the patient's clinical status, although lower in disseminated forms, probably due to concomitant HIV infection. A hypergammaglobulinaemia was also found in most leprosy and TB patients. In TB this was due to increased IgG1 and IgG3, especially in HIV co-infected patients. Based on the current knowledge of the influence of T cell-secreted cytokines on human immunoglobulin isotype expression, these results do not fit with a putative role of Th1 (such as found in TB and tuberculoid leprosy (TT)) and Th2 (such as found in leprosy lepromatous (LL) leprosy) environment in the isotypy of antibody responses in mycobacterial infections. Nor do variations of isotypy according to pathological conditions seem to be related to the biochemical nature of antigens, since antibodies to LAM and protein antigens had comparable evolutions of their subclass distribution. Other factors are to be investigated in order to understand better the significance and possible roles of antibodies in mycobacterial diseases.