Tegumental Ca-stimulated adenosine triphosphatase activity in adult Schistosoma mansoni worms

A Ca-stimulated ATPase activity (pH 9.5) associated with the tegumental membrane enriched (TME) fraction of Schistosoma mansoni adults was partially inhibited by NAP-taurine or by increasing concentrations of chlorpromazine; endogenous calmodulin was found associated with the TME fraction. A similar activity (pH 8.6) was histochemically visualized whithin the tegument of fixed worms on the cytoplasmic leaflet of both the doubel surface membrane and the basement membrane; this reaction was inhibited by 1 µM chloropromazine and it was also observed on the inner side of double membrane vesicles present in the TME fraction. No ATPase activity could be seen at alkaline pH with added Mg or Na/K ions. Without ATP, the addition of external Ca to the fixed worms induced the appearance of lead precipitates on the tegumental discoid bodies; this reaction was inhibited by molybdate and not by chlorpromazine. The intrategumentary regulation of calcium by the systems described and the possible use of phenothiazines against schistosimes are discussed.

The value of adenosine deaminase (ADA) determination in the diagnosis of tuberculous ascites

In order to evaluate the role of the determination of adenosine deaminase activity (ADA) in ascitic fluid for the diagnosis of tuberculosis, 44 patients were studied. Based on biochemical, cytological, histopathological and microbiological tests, the patients were divided into 5 groups: G1 - tuberculous ascites (n = 8); G2 - malignant ascites (n = 13); G3 - spontaneous bacterial peritonitis (n = 6); G4 - pancreatic ascites (n = 2); G5 - miscelaneous ascites (n = 15). ADA concentration were significantly higher in G1 (133.50 ± 24.74 U/l) compared to the other groups (G2 = 41.85 ± 52.07 U/l; G3 = 10.63 ± 5.87 U/l; G4 = 18.00 ± 7.07 U/l; G5 = 11.23 ± 7.66 U/l). At a cut-off value of >31 U/l, the sensitivity, specificity and positive and negative preditive values were 100%, 92%, 72% and 100%, respectively. ADA concentrations as high as in tuberculous ascites were only found in two malignant ascites caused by lymphoma. We conclude that ADA determination in ascitic fluid is a useful and reliable screening test for diagnosing tuberculous ascites. Values of ADA higher than 31 U/l indicate more invasive methods to confirm the diagnosis of tuberculosis.

The usefulness of adenosine deaminase in the diagnosis of tuberculous pericarditis

The objective of this study was to evaluate the adenosine deaminase (ADA) activity usefulness in the diagnosis of tuberculous pericarditis (TP), comparing its value with pericardial effusions (PE) caused by other pericardial diseases. A retrospective case-control study was conducted with nine cases of TP and 39 other than TP diseases (12 neoplastic, 11 septic and 16 unknown origin). Every patient included in this study had PE samples submitted to ADA activity measures and microbiological analysis, and then had pericardial tissue samples submitted to microbiological and histopathological examination. Considering the value of 40 U/L as the cut-off for the diagnosis of TP, the specificity and sensitivity were respectively of 72% and 89%. The specificity of ADA activity for the TP was best applied in the differential diagnosis from PE of unknown origin. The present study demonstrates the clinical value of the measurement of ADA activity in PE in the diagnosis of TP.

ADENOSINE DEAMINASE ACTIVITY AND SERUM C-REACTIVE PROTEIN AS PROGNOSTIC MARKERS OF CHAGAS DISEASE SEVERITY

SUMMARY Chagas disease is a public health problem worldwide. The availability of diagnostic tools to predict the development of chronic Chagas cardiomyopathy is crucial to reduce morbidity and mortality. Here we analyze the prognostic value of adenosine deaminase serum activity (ADA) and C-reactive protein serum levels (CRP) in chagasic individuals. One hundred and ten individuals, 28 healthy and 82 chagasic patients were divided according to disease severity in phase I (n = 35), II (n = 29), and III (n = 18). A complete medical history, 12-lead electrocardiogram, chest X-ray, and M-mode echocardiogram were performed on each individual. Diagnosis of Chagas disease was confirmed by ELISA and MABA using recombinant antigens; ADA was determined spectrophotometrically and CRP by ELISA. The results have shown that CRP and ADA increased linearly in relation to disease phase, CRP being significantly higher in phase III and ADA at all phases. Also, CRP and ADA were positively correlated with echocardiographic parameters of cardiac remodeling and with electrocardiographic abnormalities, and negatively with ejection fraction. CRP and ADA were higher in patients with cardiothoracic index ≥ 50%, while ADA was higher in patients with ventricular repolarization disturbances. Finally, CRP was positively correlated with ADA. In conclusion, ADA and CRP are prognostic markers of cardiac dysfunction and remodeling in Chagas disease.

Factors affecting Helicobacter pylori eradication using a seven-day triple therapy with a proton pump inhibitor, tinidazole and clarithromycin, in brazilian patients with peptic ulcer

Triple therapy is accepted as the treatment of choice for H. pylori eradication. In industrialized countries, a proton pump inhibitor plus clarithromycin and amoxicillin or nitroimidazole have shown the best results. Our aims were: 1. To study the eradication rate of the association of a proton pump inhibitor plus tinidazole and clarithromycin on H. pylori infection in our population. 2. To determine if previous treatments, gender, age, tobacco, alcohol use, and non-steroidal anti-inflammatory drugs (NSAIDs) change the response to therapy. METHODS: Two hundred patients with peptic ulcer (upper endoscopy) and H. pylori infection (histology and rapid urease test - RUT) were included. A proton pump inhibitor (lansoprazole 30 mg or omeprazole 20 mg), tinidazole 500 mg, and clarithromycin 250 mg were dispensed twice a day for a seven-day period. Eradication was assessed after 10 to 12 weeks of treatment through histology and RUT. RESULTS: The eradication rate of H. pylori per protocol was 65% (128/196 patients). This rate was 53% for previously treated patients, rising to 76% for not previously treated patients, with a statistical difference p<0.01. No significant difference was observed regarding sex, tobacco use, alcohol consumption, and NSAID use, but for elderly patients the difference was p = 0.05. Adherence to treatment was good, and side effects were mild. CONCLUSIONS: A proton pump inhibitor, tinidazole, and clarithromycin bid for seven days resulted in H. pylori eradication in 65% of the patients. Previous treatments were the main cause of treatment failure.

Proton magnetic resonance spectroscopy of the frontal lobe in schizophrenics: a critical review of the methodology

Schizophrenic patients undergoing proton magnetic resonance spectroscopy show alterations in N-acetyl aspartate levels in several brain regions, indicating neuronal dysfunction. The present review focuses on the main proton magnetic resonance spectroscopy studies in the frontal lobe of schizophrenics. A MEDLINE search, from 1991 to March 2004, was carried out using the key-words spectroscopy and schizophrenia and proton and frontal. In addition, articles cited in the reference list of the studies obtained through MEDLINE were included. As a result, 27 articles were selected. The results were inconsistent, 19 papers reporting changes in the N-acetyl aspartate levels, while 8 reported no change. Methodological analysis led to the conclusion that the discrepancy may be due the following factors: (i) number of participants; (ii) variation in the clinical and demographic characteristics of the groups; (iii) little standardization of the acquisition parameters of spectroscopy. Overall, studies that fulfill strict methodological criteria show N-acetyl aspartate decrease in the frontal lobe of male schizophrenics.

Fetal tachyarrhythmia with 1:1 atrioventricular conduction. Adenosine infusion in the umbilical vein as a diagnostic test

This is the report of a case of fetal tachyarrhythmia with 1:1 atrioventricular conduction detected by pre-natal echocardiography in a fetus at 25-weeks gestation. Adenosine infusion via cordocentesis was performed as a diagnostic test to differentiate between atrioventricular nodal reentrant supraventricular tachyarrhythmia and atrial flutter. After infusion, transient 2:1 atrioventricular dissociation was obtained and the diagnosis of atrial flutter was made. Transplacental therapy with digoxin and amiodarone was then successfully used.

Study of Coronary Flow Reserve with Intravenous Use of Microbubbles (Contrast Echocardiography) and Adenosine: Protocol for Clinical Application in Patients Suspected of Having Coronary Heart Disease

OBJECTIVE: To test the feasibility, safety and accuracy of the adenosine protocol in the study of myocardial perfusion with microbubbles contrast echocardiography. METHODS: 81 pts (64 male, 60+11 years) were submitted to contrast echocardiography with PESDA (sonicated solution of albumin 20%-1ml, dextrose 5%-12ml and deca-fluorobutane gas-8ml) to study the myocardial perfusion at rest and after bolus injection of adenosine (6 to 18mg) and to coronary angiography within 1 month each other. For each patient 3 left ventricle perfusion beds were considered (total of 243 territories). 208 territories were analyzed and 35 territories were excluded. PESDA was continuously infused (1-2ml/min), titrated for best myocardial contrast. Triggered (1:1) second harmonic imaging was used. RESULTS: Coronary angiography showed 70 flow limiting (> 75%) lesions and 138 no flow limiting lesions. At rest an obvious myocardium contrast enhancement was seen in at least 1 segment of a territory in all patients. After adenosine injection an unquestionable further increase in myocardial contrast was observed in 136 territories (99%) related to no flow limiting lesions, lasting < 10 s, and a myocardial perfusion defect was detected in 68 territories (97%) related to flow limiting lesions. It was observed only 4 false results. There were no serious complications. CONCLUSION: Myocardial perfusion study with PESDA and adenosine protocol is a practical, safe and accurate method to analyze the coronary flow reserve.

Adenosine Deaminase Activities in Sera, Lymphocytes and Granulocytes in Patients with Cutaneous Leishmaniasis

Adenosine deaminase (ADA) activities in sera, lymphocytes and granulocytes in patients with cutaneous leishmaniasis were investigated and compared with control groups. Fifty patients and 50 healthy individuals were studied. The clinical diagnosis was parasitologically confirmed by culture and Giemsa stain. ADA activities were measured by colorimetric method. Serum ADA activities 37.80 ± 11.90, 18.28 ± 6.08 IU/L (p<0.0001), lymphocyte specific ADA activities 14.90 ± 7.42, 8.38 ± 7.42 U/mg protein (p = 0.04), granulocyte specific ADA activities 1.15 ± 0.73 , 1.09 ± 0.67 U/mg protein ( p>0.05) were found in patients and control groups, respectively. ADA activity increases in some infectious diseases were cell mediated immune mechanisms are dominant. In cutaneous leishmaniasis, lymphokine-mediated macrophage activity is the main effector mechanism. Increase in serum and lymphocyte ADA activities in patients with cutaneous leishmaniasis may be dependent on and reflects the increase in phagocytic activity of macrophages and maturation of T-lymphocytes.

Adenosine Deaminase and Guanosine Deaminase Activities in Sera of Patients with Viral Hepatitis

In order to investigate purin and primidin metabolism pathways in hepatitis, adenosine deaminase (ADA) and guanosine deaminase (GDA) activities in sera of patients with different types and manifestations of viral hepatitis disease (A, B, C, D, E, chronic, acute) were investigated and compared with the control group of healthy individuals. Hepatitis cases were classified with respect to their serological findings and clinics. When compared all the hepatitis cases with the controls, levels of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase enzymes, as well as ADA and GDA, were significantly higher than the control group (p<0.01). Levels of ADA and GDA in hepatitis cases were determined as 26.07±11.98 IU/l and 2.37±1.91 IU/l, respectively. When compared their ADA and GDA levels amongst the classified hepatitis groups, there was no difference in ADA levels amongst cases (p>0.05). However, GDA levels in hepatitis A group were closed to the controls. Increase in serum ADA activities in hepatitis forms may be dependent on and reflect the increase in phagocytic activity of macrophages and maturation of T-lymphocytes, and may be valuable in monitoring in viral hepatitis cases.

Evaluation of adenosine deaminase seric activity in the diagnosis of bovine tuberculosis

Determination of seric levels of adenosine deaminase (ADA), an enzyme produced by monocytes/macrophages and lymphocytes, has been used in the diagnosis of human tuberculosis (TB). In the present study, ADA seric activity was evaluated comparatively to the comparative tuberculin test in the diagnosis of bovine tuberculosis. Two hundred fifty-six cattle were classified by origin and by the comparative tuberculin test as TB-positive animals (n = 52, from herds where the Mycobacterium bovis had previously been isolated), and TB-negative animals (n = 204, TB-free herds). The mean ADA seric value from the TB-positive group (4.45 ± 2.33 U/L) was significantly lower (p = 0.008) than that observed in sera from the TB-negative group (6.12 ± 4.47 U/L). When animals from a herd with clinical cases of enzootic bovine leukosis of TB-negative group were withdrawn from analysis, the mean ADA seric values of TB-negative group (5.12 ± 3.75 U/L) was not significantly different anymore from that of the TB-positive group (p = 0.28). There was no agreement in the diagnosis of bovine TB between comparative tuberculin test and determination of ADA seric values, using two different cutoff points, being 6.12 U/L and 15.0 U/L, (kappa = -0.086 and kappa = -0.082, respectively). In conclusion, the determination of ADA seric activity was not a good auxiliary test for bovine TB, because it was not able to distinguish between TB-positive and TB-negative animals.

Modulatory effect of iron chelators on adenosine deaminase activity and gene expression in Trichomonas vaginalis

Trichomonas vaginalis is a flagellate protozoan that parasitises the urogenital human tract and causes trichomoniasis. During the infection, the acquisition of nutrients, such as iron and purine and pyrimidine nucleosides, is essential for the survival of the parasite. The enzymes for purinergic signalling, including adenosine deaminase (ADA), which degrades adenosine to inosine, have been characterised in T. vaginalis. In the evaluation of the ADA profile in different T. vaginalisisolates treated with different iron sources or with limited iron availability, a decrease in activity and an increase in ADA gene expression after iron limitation by 2,2-bipyridyl and ferrozine chelators were observed. This supported the hypothesis that iron can modulate the activity of the enzymes involved in purinergic signalling. Under bovine serum limitation conditions, no significant differences were observed. The results obtained in this study allow for the assessment of important aspects of ADA and contribute to a better understanding of the purinergic system in T. vaginalis and the role of iron in establishing infection and parasite survival.

Possible involvement of A1 receptors in the inhibition of gonadotropin secretion induced by adenosine in rat hemipituitaries in vitro

We investigated the participation of A1 or A2 receptors in the gonadotrope and their role in the regulation of LH and FSH secretion in adult rat hemipituitary preparations, using adenosine analogues. A dose-dependent inhibition of LH and FSH secretion was observed after the administration of graded doses of the R-isomer of phenylisopropyladenosine (R-PIA; 1 nM, 10 nM, 100 nM, 1 µM and 10 µM). The effect of R-PIA (10 nM) was blocked by the addition of 8-cyclopentyltheophylline (CPT), a selective A1 adenosine receptor antagonist, at the dose of 1 µM. The addition of an A2 receptor-specific agonist, 5-N-methylcarboxamidoadenosine (MECA), at the doses of 1 nM to 1 µM had no significant effect on LH or FSH secretion, suggesting the absence of this receptor subtype in the gonadotrope. However, a sharp inhibition of the basal secretion of these gonadotropins was observed after the administration of 10 µM MECA. This effect mimicked the inhibition induced by R-PIA, supporting the hypothesis of the presence of A1 receptors in the gonadotrope. R-PIA (1 nM to 1 µM) also inhibited the secretion of LH and FSH induced by phospholipase C (0.5 IU/ml) in a dose-dependent manner. These results suggest the presence of A1 receptors and the absence of A2 receptors in the gonadotrope. It is possible that the inhibition of LH and FSH secretion resulting from the activation of A1 receptors may have occurred independently of the increase in membrane phosphoinositide synthesis.

Uptake of NO-releasing drugs by the P2 nucleoside transporter in trypanosomes

Nitric oxide (NO·) has been identified as a principal regulatory molecule of the immune system and the major cytotoxic mediator of activated immune cells. NO· can also react rapidly with a variety of biological species, particularly with the superoxide radical anion O2·- at almost diffusion-limited rates to form peroxynitrite anion (ONOO-). ONOO- and its proton-catalyzed decomposition products are capable of oxidizing a great diversity of biomolecules and can act as a source of toxic hydroxyl radicals. As a consequence, a strategy for the development of molecules with potential trypanocidal activities could be developed to increase the concentration of nitric oxide in the parasites through NO·-releasing compounds. In this way, the rate of formation of peroxynitrite from NO· and O2·- would be faster than the rate of dismutation of superoxide radicals by superoxide dismutases which constitute the primary antioxidant enzymatic defense system in trypanosomes. The adenosine transport systems of parasitic protozoa, which are also in certain cases implicated in the selective uptake of active drugs such as melarsoprol or pentamidine, could be exploited to specifically target these NO·-releasing compounds inside the parasites. In this work, we present the synthesis, characterization and biological evaluation of a series of molecules that contain both a group which would specifically target these drugs inside the parasites via the purine transporter, and an NO·-donor group that would exert a specific pharmacological effect by increasing NO level, and thus the peroxynitrite concentration inside the parasite.