Structural complexes of human adenine phosphoribosyltransferase reveal novel features of the APRT catalytic mechanism

Adenine phosphoribosyltransferase (APRT) is an important enzyme component of the purine recycling pathway. Parasitic protozoa of the order Kinetoplastida are unable to synthesize purines de novo and use the salvage pathway for the synthesis of purine bases rendering this biosynthetic pathway an attractive target for antiparasitic drug design. The recombinant human adenine phosphoribosyltransferase (hAPRT) structure was resolved in the presence of AMP in the active site to 1.76 angstrom resolution and with the substrates PRPP and adenine simultaneously bound to the catalytic site to 1.83 angstrom resolution. An additional structure was solved containing one subunit of the dimer in the apo-form to 2.10 angstrom resolution. Comparisons of these three hAPRT structures with other `type I` PRTases revealed several important features of this class of enzymes. Our data indicate that the flexible loop structure adopts an open conformation before and after binding of both substrates adenine and PRPR Comparative analyses presented here provide structural evidence to propose the role of Glu 104 as the residue that abstracts the proton of adenine N9 atom before its nucleophilic attack on the PRPP anomeric carbon. This work leads to new insights to the understanding of the APRT catalytic mechanism.

Fight versus flight: the interaction of temperature and body size determines antipredator behaviour in tegu lizards

Ectotherm antipredator behaviour might be strongly affected both by body temperature and size: when environmental temperatures do not favour maximal locomotor performance, large individuals may confront predators, whereas small animals may flee, simply because they have no other option. However, integration of body size and temperature effects is rarely approached in the study of antipredator behaviour in vertebrate ectotherms. In the present study we investigated whether temperature affects antipredator responses of tegu lizards, Tupinambis merianae, with distinct body sizes, testing the hypothesis that small tegus (juveniles) run away from predators regardless of the environmental temperature, because defensive aggression may not be an effective predator deterrent, whereas adults, which are larger, use aggressive defence at low temperatures, when running performance might be suboptimal. We recorded responses of juvenile (small) and adult (large) tegu lizards to a simulated predatory attack at five environmental temperatures in the laboratory. Most differences between the two size classes were observed at low temperatures: large tegus were more aggressive overall than were small tegus at all temperatures tested, but at lower temperatures, the small lizards often used escape responses whereas the large ones either adopted a defensive posture or remained inactive. These results provide strong evidence that body size and temperature affect the antipredator responses of vertebrate ectotherms. We discuss the complex and intricate network of evolutionary and ecological parameters that are likely to be involved in the evolution of such interactions. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

L-Allylglycine dissociates the neural substrates of fear in the periaqueductal gray of rats

The dorsal (dPAG) and ventral (vPAG) regions of the periaqueductal gray are well known to contain the neural substrates of fear and anxiety. Chemical or electrical stimulation of the dPAG induces freezing, followed by a robust behavioral reaction that has been considered an animal model of panic attack. In contrast, the vPAG is part of a neural system, in which immobility is the usual response to its stimulation. The defense reaction induced by the stimulation of either region is accompanied by anti nociception. Although GABAergic mechanisms are known to exert tonic inhibitory control on the neural substrates of fear in the dPAG, the role of these mechanisms in the vPAG is still unclear. The present study examined defensive behaviors and antinociception induced by microinjections of an inhibitor of gamma-aminobutyric acid synthesis, L-allylglycine (L-AG; 1, 3, and 5 mu g/0.2 mu l), into either the dPAG or vPAG of rats subjected to the open field and tail-flick tests. Passive or tense immobility was the predominant behavior after L-AG (1 or 3 mu g) microinjection into the vPAG and dPAG, respectively, which was replaced with intense hyperactivity, including jumps or rearings, after injections of a higher dose (5 mu g/0.2 mu l) into the dPAG or vPAG. Moreover, whereas intra-dPAG injection of 3 mu g L-AG produced intense antinociception, only weak antinociception was induced by intra-vPAG injections of 5 mu g L-AG. These findings suggest that GABA mechanisms are involved in the mediation of antinociception and behavioral inhibition to aversive stimulation of the vPAG and exert powerful control over the neural substrates of fear in the dPAG to prevent a full-blown defense reaction possibly associated with panic disorder. (C) 2009 Elsevier Inc. All rights reserved.

Mannose-binding lectin gene polymorphism and resistance to therapy in women with recurrent vulvovaginal candidiasis

Precis Women with recurrent vulvovaginal candidiasis (RVC) due to a polymorphism in codon 54 of the MBL2 gene respond better to fluconazole maintenance therapy than do women with other underlying causes. Objective To explain differences in response rates to maintenance therapy with fluconazole in women suffering from RVC by evaluating associations with a polymorphism in the gene coding for mannose-binding lectin (MBL). Design Follow-up study, neted case-control group. Setting Women attending vulvoginitis clinic for RVC. Population Women participating in a multicentric study in Belgium with a degressive dose of fluconazole for RVC (the ReCiDiF trial) were divided into good responders, intermediate responders and nonresponders according to the number of relapses they experienced during therapy. From 109 of these women with adequate follow-up data, vaginal lavage with 2 ml of saline were performed at the moment of a proven acute attack at inclusion in the study, before maintenance treatment was started. A buccal swab was obtained from 55 age-matched women without a history of Candida infections, serving as a control group. Methods Extracted DNA from buccal or vaginal cells was tested for codon 54 MBL2 gene polymorphism by polymerase chain reaction and endonuclease digestion. Main outcome measures Frequency of MBL2 condon 54 allele B in women with optimal or poor response to maintenance therapy in composition with controls. Results Women (n = 109) suffering from RVC were more likely to carry the variant MBL2 codon 54 allele B than control women (20 versus 6.6%, OR 3.4 [95% CI 1.3-8.2], P = 0.01). B alleles were present in 25% of the 36 women not suffering from any recurrence during the maintenance therapy with decreasing doses of fluconazole (OR 4.9 [95% CI 1.9-12.5], P = 0.0007 versus controls), in 20% of the 43 women with sporadic recurrences (OR 3.6 [95% CI 1.4-9.2], P = 0.007 versus controls) and in 15% of the 30 women who had to interrupt the treatment regimen due to frequent relapses (P = 0.097 versus controls). Conclusions The MBL2 codon 54 gene polymorphism is more frequent in Belgian women suffering from RVC than in controls. The presence of the B allele is associated with a superior response to fluconazole maintenance therapy as compared with RVC patients without this polymorphism. We conclude that RVC due to deficient MBL production is more easily helped with antifungal medication than is RVC due to some other mechanism.

Status epilepticus and lymphocytic pneumonitis following hepatitis B vaccination

The case reported refers to a patient who developed status epilepticus in the day of her third dose of hepatitis B vaccination and we review the literature on this subject. A 12 year-old girl, without a relevant previous history, taking no drugs, developed a seizure attack followed by unconsciousness, and eventually died after three days of her third dose of hepatitis B (HB) vaccination. Autopsy study revealed cerebral edema with congestion and herniation and diffuse interstitial type pneumonitis. There seem to be a straight forward time relationship between the third HB vaccine, the event of convulsion and the sudden death of the patient. We suggest that, in some cases, vaccination may be the triggering factor for autoimmune and neurological disturbances in genetically predisposed individuals and physicians should be aware of this possible association. (c) 2007 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

MHC class I and II expression in juvenile dermatomyositis skeletal muscle

Objective To assess MHC I and II expressions in muscle fibres of juvenile dermatomyositis (JDM) and compare with the expression in polymyositis (PM), dermatomyositis (DM) and dystrophy. Patients and methods Forty-eight JDM patients and 17 controls (8 PM, 5 DM and 4 dystrophy) were studied. The mean age at disease onset was 7.1 +/- 3.0 years and the mean duration of weakness before biopsy was 9.4 +/- 12.9 months. Routine histochemistry and immunohistochemistry (StreptABComplex/HRP) for MHC I and II (Dakopatts) were performed on serial frozen muscle sections in all patients. Mann-Whitney, Kruskal Wallis, chi-square and Fisher`s exact statistical methods were used. Results MHC I expression was positive in 47 (97.9%) JDM cases. This expression was observed independent of time of disease corticotherapy previous to muscle biopsy and to the grading of inflammation observed in clinical, laboratorial and histological parameters. The expression of MHC I was similar on JDM, PM and DM, and lower in dystrophy. On the other hand, MHC II expression was positive in just 28.2% of JDM cases was correlated to histological features as inflammatory infiltrate, increased connective tissue and VAS for global degree of abnormality (p < 0.05). MCH II expression was similar in DM/PM and lower in JDM and dystrophy, and it was based on the frequency of positive staining rather than to the degree of the MCH II expression. Conclusions MHC I expression in muscle fibres is a premature and late marker of JDM patient independent to corticotherapy, and MHC II expression was lower in JDM than in PM and DM.

PENILE AND SCROTUM SWELLING IN JUVENILE DERMATOMYOSITIS

Edema is a well-known feature of juvenile dermatomyositis (JDM). However, to our knowledge localized penile and scrotum swelling was not previously reported. During a 27-year period, 5,506 patients were followed up at the Pediatric Rheumatology Unit of our University Hospital and 157 patients (2.9%) had JDM. One of them (0.6%) had concomitant localized penile and scrotum swelling. He had severe disease activity since he was 7-year-old, manifested by diffuse cutaneous vasculitis, recurrent localized edema (limbs or face) and only one episode of generalized edema. At the age of 10, he presented edema of the genitalia associated with mild skin erythema. Penis, scrotum and testicular ultrasound as well as magnetic resonance imaging showed skin edema without testicular involvement. He was taking prednisone, methotrexate, cyclosporin, hydroxychloroquine and thalidomide. Improvement of skin rash, penile and scrotum swelling was noticed only with rituximab therapy. No adverse event was observed during anti-CD20 infusions and after six months of follow up. Penile and scrotum edema was a rare manifestation of JDM which improved with anti-CD20 monoclonal antibody treatment.

Recurrent neuromyelitis optica in Brazilian patients: clinical, immunological, and neuroimaging characteristics

Neuromyelitis optica has not been thoroughly studied in Brazilian patients following the discovery of NMO-IgG and its specific antigen aquaporin-4. In this study we aimed to describe the clinical NMO-IgG immunological status and neuroimaging characteristics of recurrent neuromyelitis optica in a series Brazilian patients. We undertook a retrospective study of 28 patients with recurrent neuromyelitis optica, according to 1999 Wingerchuk`s diagnostic criteria. Data on NMO-IgG status, clinical features, and MRI findings were analyzed. Three men and 25 women were evaluated. Median age at onset of disease was 26 years (range 7-55); median time of follow-up was 7 years (range 2-14). The mean time elapsed between the first and the second attack was 17 months (median 8.5; range 2-88). NMO-IgG was detected in 18 patients (64.3%). Four patients died due to respiratory failure. Most patients presented with cervical (36%) and cervical-thoracic myelitis (46.4%). Holocord lesion was the most common pattern of involvement (50%) on the axial plane. We did not find a statistical association between myelitis extension and NMO-IgG result. Our series of Brazilian patients showed a younger age of onset than previously reported. In our series, in contrast to previous reports, there was no correlation between the extension of myelitis and NMO-IgG positivity.

Role of olfaction and vision cues in feeding behavior and alarm reaction in the catfish pintado, Pseudoplatystoma corruscans

Experiments were performed to investigate senses that are essential for mediating fright reaction and food behavior in Pseudoplatystoma corruscans, pintado. The dilemma ""to feed or to flee"" was also analyzed in fishes with intact and sectioned olfactory tracts, stimulated by alarm substance extracts and food. Fishes were arranged into five groups: fish with intact lateral olfactory tracts (LOT), fish with intact medial olfactory tract (MOT), fish with tracts totally sectioned (TOTAL, both LOT and MOT), sham operated, and nonoperated fish. The five groups were submitted to either alarm substance extract and food stimulus or to distilled water (control) and food stimulus. Fish reacted to food independently of which tract (LOT, MOT or TOTAL) was sectioned; vision seems necessary and elemental to detect and deflagrate food response. Latency of the responses to each reaction was different between groups. None of the fish with sectioned tracts reacted to alarm substance extract, while sham- and nonoperated fish showed the typical alarm behavior response, leading to the conclusion that olfaction is essential for mediating alarm response. These results indicate that others sense systems (e.g., vision) are sufficient to trigger and elicit feeding behavior and that olfaction is not necessary to fully maintain food detection to qualitative and quantitative extent. However, olfactory tract integrity seems to be required for mediation of alarm reaction in P. corruscans.

Depersonalization and personality in panic disorder

Background: Prevalence and clinical correlates of depersonalization symptoms have been associated with panic disorder. Personality traits might increase the likelihood of experiencing depersonalization symptoms or depersonalization disorder in panic patients. Aims: The objectives of this study are to establish the prevalence of depersonalization symptoms during the panic attack and in depersonalization disorder and to examine the personality factors associated with the presence of depersonalization in patients with panic disorder. Methods: The sample comprised 104 consecutive adult outpatients with panic disorder, diagnosed according to the Semistructured Clinical Interview for DSM-IV (Axis I/II disorders). Participants were assessed with the Cambridge Depersonalization Scales, the Temperament and Character Inventory, and the Panic and Agoraphobia Scale. Results: Forty-eight percent of the sample had depersonalization symptoms during the panic attack, whereas 20% of patients had a depersonalization disorder. Women presented more depersonalization disorders than did men (P = .036). Patients with panic disorder with depersonalization disorder had a more severe panic disorder (P = .002). Logistic regression analysis showed that self-transcendence trait (odds ratio, 1.089; 95% confidence interval, 1.021-1.162; P = .010) and severity of panic (odds ratio, 1.056; 95% confidence interval, 1.005-1.110; P = .032) were independently associated with depersonalization disorder. Conclusions: A high prevalence of depersonalization symptoms and depersonalization disorder was confirmed in patients with panic disorder, supporting a dosage effect model for understanding depersonalization pathology. Self-transcendence trait and severity of panic disorder were reported as risk factors for depersonalization disorder. (C) 2011 Elsevier Inc. All rights reserved.

Neurobiology of panic disorder: From animal models to brain neuroimaging

Evidence from animal models of anxiety has led to the hypothesis that serotonin enhances inhibitory avoidance (related to anxiety) in the forebrain, but inhibits one-way escape (panic) in the midbrain periaqueductal gray (PAG). Stressing the difference between these emotions, neuroendocrinological results indicate that the hypothalamic-pituitary-adrenal axis is activated by anticipatory anxiety, but not by panic attack nor by electrical stimulation of the rat PAG. Functional neuroimaging has shown activation of the insula and upper brain stem (including PAG), as well as deactivation of the anterior cingulated cortex (ACC) during experimental panic attacks. Voxel-based morphometric analysis of brain magnetic resonance images has shown a grey matter volume increase in the insula and upper brain stem, and a decrease in the ACC of panic patients at rest, as compared to healthy controls. The insula and the ACC detect interoceptive stimuli, which are overestimated by panic patients. It is suggested that these brain areas and the PAG are involved in the pathophysiology of panic disorder. (C) 2008 Elsevier Ltd. All rights reserved.

Characterization of a chromium-rich tannery waste and its potential use in ceramics

Leather industries which promote hide stabilization by the conventional chrome-tanning process are a major source of pollution because of the resultant chromium-rich wastes. In this work, an extensive characterization of such a chromium-rich waste sludge is presented, regarding its chemical composition (XRF), crystalline phase contents (XRD), organic carbon content (TOC), thermal behavior by thermogravimetry (TG) and differential scanning calorimetry (DSC), as well as its stability under chemical attack (the concentration of important ions in the leachates being determined by capillary electrophoresis) and when submitted to temperatures as high as 1100 degrees C, in air. The material showed the tendency to produce some undesirable, and previously non-detected hexavalent chromium when exposed to high temperatures, but after washing off the soluble salts and the elimination of the organic matter by firing, the resultant material was succesfully tested as a ceramic pigment in a conventional glaze composition usually employed in the ceramic the industry. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

In vitro evidence for immune evasion activity by human plasmin associated to pathogenic Leptospira interrogans

Leptospirosis is a widespread re-emerging zoonosis of human and veterinary concern. It has been shown that virulent leptospires protect themselves against the host`s innate immune system, a strategy that allows the bacteria to reach immunologically safe environments. Although extensive studies on host pathogen interactions have been performed, little is known on how leptospires deal with host immune attack. In a previous work, we demonstrated the ability of leptospires to bind human plasminogen (PLC), that after treatment with activators, conferred plasmin (PLA) activity on the bacteria surface. In this study, we show that the PLA activity associated to the outer surface of Leptospira could interfere with the host immune attack by conferring some evasion advantage during infection. We demonstrate that PLA-coated leptospires interfere with complement Ob and IgG depositions on the bacterial surface, probably through the degradation of these components, thus diminishing opsonization process. Similar decrease on the deposition was observed when normal and immune sera from patients diagnosed with leptospirosis were employed as a source of IgG. We believe that decreasing opsonization by PLA generation might be an important aspect of the leptospiral immune escape strategy and survival. To our knowledge, this is the first proteolytic activity of plasmin associated-Leptospira related to anti-opsonic properties reported to date. (C) 2011 Elsevier Ltd. All rights reserved.

Effects of Erosive, Cariogenic or Combined Erosive/Cariogenic Challenges on Human Enamel An in situ/ex vivo Study

Individuals with cariogenic diet can also consume erosive beverages. Thus, it seems necessary to investigate a possible caries/erosion interaction. To test in situ/ex vivo a combination of these challenges, 11 subjects wore intraoral appliances containing four enamel blocks randomly assigned. In the first 2-week phase, the appliances were immersed in a cola drink 3 times/day. Two blocks were free of plaque (erosion only: EO) and two blocks were covered with plaque (erosion + plaque: EP). In the second 2-week phase, four new blocks were all covered with plaque and subjected to a sucrose solution 8 times/day. Among the four new blocks, two were also subjected to the cola drink 3 times/day (erosion + caries: EC) while the other two were not (caries only: CO). Thus, in EO, the specimens were fixed at the intraoral appliance level. In EP, EC and CO they were fixed 1.0 mm under the appliance level and covered with plastic meshes for dental plaque accumulation. Changes in wear and hardness were measured. Data were tested using ANOVA and Tukey`s test (p < 0.05). Mean values of wear (mu m) and change in hardness (kp/mm(2)) were: EO 4.82/310; EP 0.14/48; EC 0.34/245; CO 0.42/309. With respect to surface softening, EP and EC differed significantly from each other and from EO and CO, which did not differ significantly. EO presented significantly higher wear than the other groups. The data suggest that the presence of dental plaque can decrease the acid attack of an erosive drink and the association of erosive and cariogenic challenges showed less enamel alterations when compared to erosive or cariogenic challenges only. Copyright (C) 2008 S. Karger AG, Basel

Different circulating metalloproteinases profiles in women with migraine with and without aura

Background: We compared the circulating levels of matrix metalloproteinase (MMP)-2. MMP-9, tissue inhibitors of metal loproteinase (TIMP)-1, TIMP-2, and MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios in migraine patients without aura (MWA) and in migraine patients with aura (MA) with those found in healthy subjects (controls). Methods: We studied 80 migraine (40 MWA and 40 MA) women and 40 controls. Pro-MMP-2 levels were determined by zymography and MMP-9, TIMP-1, and TIMP-2 levels were determined by ELISA. Results: While we found similar TIMP-2 levels, higher plasma pro-MMP-2 and pro-MMP-2/TIMP-2 ratios were found in MWA and MA patients compared with controls (P<0.05). Higher TIMP-1 levels and lower MMP-9/TIMP-1 ratio were found in MA, but not in MWA, patients compared with controls (P<0.05). We found no significant differences when patients without headache attack were compared with patients having a headache attack (all P<0.05). Conclusions: We showed an increased net MMP-2 activity in MWA and MA. The increased MMP-9/TIMP-1 ratios in MWA patients contrast with the lower MMP-9/TIMP-1 ratios in MA patients and may reflect pathophysiological differences between these conditions. (C) 2009 Elsevier B.V. All rights reserved.