Different brain oxidative and neuroinflammation status in rats during prolonged abstinence depending on their ethanol relapse-like drinking behavior: Effects of ethanol reintroduction.

RATIONALE: Accumulating evidence suggests that chronic alcohol consumption is associated with excessive oxidative damage and neuroinflammatory processes and these events have been associated to early alcohol withdrawal. In the present research we wonder if brain oxidative stress and neuroinflammation remains altered during prolonged withdrawal situations and whether these alterations can be correlated with relapse behavior in alcohol consumption. The effects of alcohol reintroduction were also evaluated METHODS: We have used a model based on the alcohol deprivation effect (ADE) within a cohort of wild-type male Wistar rats. Two subpopulations were identified according to the alcohol relapse-like drinking behavior displayed (ADE and NO-ADE subpopulations). Oxidized and reduced glutathione content was determined within the hippocampus and the amygdala using a mass spectrometry method. The levels of mRNA of seven different inflammatory mediators in the prefrontal cortex of rats were quantified. All the analyses were performed in two different conditions: after 21-day alcohol deprivation (prolonged abstinence) and after 24 h of ethanol reintroduction in both subpopulations. RESULTS: ADE and NO-ADE rats showed different endophenotypes. ADE rats always displayed a significant lower alcohol intake rate and ethanol preference than NO-ADE rats. The results also demonstrated the existence of altered brain redox and neuroinflammation status after prolonged abstinence exclusively in ADE rats. Moreover, when ethanol was reintroduced in the ADE subpopulation, altered oxidative stress and neuroinflammatory markers were restored. CONCLUSIONS: Present findings provide new mechanisms underlying the neurobiology of relapse behavior and suggest the development of new pharmacological approaches to treat alcohol-induced relapse.

Brain metabolism of ethanol and alcoholism: an update.

It has long been suggested that some of the neuropharmacological, neurochemical and behavioural effects of ethanol are mediated by its first metabolite, acetaldehyde. In spite of the well documented psychoactivity of acetaldehyde, the precise role of this compound in alcohol abuse remains a matter of intense debate among scientists devoted to the study of alcoholism. Very frequently, the main drawback has been related to the presence of adequate levels of acetaldehyde or its derivatives inside the brain after ethanol ingestion. Since penetration into the central nervous system from blood of peripherically derived acetaldehyde is very low due to the high aldehyde dehydrogenase activity at the blood-brain barrier, several authors called into question the acetaldehyde implication in the toxicity and neurobehavioral effects of ethanol. The confirmation in several laboratories of the existence of enzymatic mechanisms of ethanol oxidation in the brain has revitalized the old theories supporting the acetaldehyde contribution to alcohol abuse and alcoholism. In this paper, we review current data on the brain metabolism of ethanol. We focused on the description of the enzymatic mechanisms involved in this metabolic process, reviewing the constitutive expression, catalytic activity and inhibition and inducibility of the enzymes involved in brain ethanol metabolism. We also analyze old and recent data on their regional distribution and cellular localization in the central nervous system, with special reference to the mesocorticolimbic system, a dopaminergic brain pathway that plays an important role in drug and ethanol reinforcement.

Regional differences in mu-opioid receptor-dependent modulation of basal dopamine transmission in rat striatum.

The nigrostriatal dopamine system is implicated in the regulation of reward and motor activity. Dopamine (DA) release in dorsal striatum (DS) is controlled by the firing rate of DA neurons in substantia nigra pars compacta. However, influences at terminal level, such as those involving activation of mu opioid receptors (MORs), can play a key role in determining DA levels in striatum. Nonetheless, published data also suggest that the effect of opioid drugs on DA levels may differ depending on the DS subregion analyzed. In this study, in vivo microdialysis in rats was used to explore this regional dependence. Changes in basal DA levels induced by local retrodialysis application of DAMGO (selective MORs agonist) in three different subregions of DS along the rostro-caudal axis were studied. Our results indicate that whereas administration of 10µM DAMGO into the rostral and caudal DS significantly reduced DA levels, in medial DS an increase in DA levels was observed. These data reveal a regional-dependent MOR modulation of DA release in DS, similar to that described in the ventral striatum. Our findings may lead to a better understanding of the nigrostriatal DA system regulation.

Quantitative in vivo microdialysis in pharmacokinetic studies: some reminders.

This paper reviews the empirical methods of quantitative microdialysis that have been used to interpret the results obtained from pharmacokinetic studies. The concept of extraction efficiency or recovery and the properties of recovery in vivo (variation with flow rate, time dependency and influence of the mode of administration) are considered. The most frequently used methods for determining recovery in vivo are described and evaluated in the light of recent theoretical studies. Specifically, we review the variation of flow rate method, the very slow flow method, the no net flux method and the delivery and retrodialysis methods. Special emphasis is placed on the description of each method, demonstrating its applicability to pharmacokinetic studies conducted under steady-state or transient conditions, and also its limitations. Finally, the more relevant studies that have compared the suitability of these methods are reviewed.

Neurotoxic relationship between dopamine and iron in the striatal dopaminergic nerve terminals.

The neurotoxic effect of dopamine (DA) and iron(III) on DAergic terminals in striatum has been studied by intracerebral microdialysis technique. Twenty-four hours after surgery (day 1), DA and/or iron(III) with and without DA reuptake inhibitor, nomifensine, were perfused for 1 h. Forty-eight hours after surgery (day 2), MPP(+) 1 mM was perfused for 15 min and the output of DA was measured, its amount being directly proportional to the remaining striatal DAergic terminals, supported by tyrosine hydroxylase immunohistochemistry technique. Perfusion of exogenous DA, as well as iron(III) 10 and 100 microM, did not produce any neurotoxic effect. However, perfusion of iron(III) (333 and 1000 microM) produced a concentration-dependent toxic effect. Co-perfusion of iron(III) at non-toxic concentration (100 microM) with DA (15 microM) produced a toxic effect. Elevation of the endogenous extracellular levels of DA by inhibiting its uptake with nomifensine increased the neurotoxic effect of iron(III) in a dose-dependent manner. The use of tetrodotoxin after elevation of DA with nomifensine partially prevented the neurotoxic effect of its co-perfusion with iron(III) (100 microM). These results suggest that DAergic system could be synergistically damaged by DA and iron(III). Thus, alterations in the clearance of DA from extracellular space along with an increase of iron may have significant consequences for DAergic system toxicity.

Complex I inhibitor effect on the nigral and striatal release of dopamine in the presence and absence of nomifensine.

The effect of inhibitors of complex I respiratory chain--1-methyl-4-phenylpyridinium ion (MPP+, 10 microM) and rotenone (100 microM)--on the release and metabolism of dopamine was studied by in vivo microdialysis in the striatum and substantia nigra. Both compounds produced a marked increase in the release of dopamine in the striatum and substantia nigra, which was diminished when nomifensine (20 microM) was included in the perfusion fluid. The 3,4-dihydroxyphenylacetic acid (DOPAC) extracellular output was decreased under MPP+ (10 microM) perfusion in the striatum and substantia nigra, in the presence and in the absence of nomifensine (20 microM). However, perfusion of rotenone (100 microM) increased or had no effect on DOPAC outflow. Homovanillic acid levels were affected in the same way as DOPAC levels, but the changes were always much less pronounced. These results suggest that the neurotoxic action of MPP+ or rotenone is similar in the striatum and substantia nigra, indicating the importance of the dopamine uptake system in this neurotoxic action of MPP+ or rotenone, also suggesting that the dopamine uptake system could have low selectivity and also transports other substances such as rotenone.

Acamprosate blocks the increase in dopamine extracellular levels in nucleus accumbens evoked by chemical stimulation of the ventral hippocampus.

Recently, we have shown that acamprosate is able to modulate extracellular dopamine (DA) levels in the nucleus accumbens (NAc) and may act as an antagonist of N-methyl-D-aspartate (NMDA) receptors. Neurochemical studies show that chemical stimulation (using NMDA) of the ventral subiculum (vSub) of the hippocampus produces robust and sustained increases in extracellular DA levels in the NAc, an effect mediated through ionotropic glutamate (iGlu) receptors. The present study examines whether acamprosate locally infused in the NAc of rats could block or attenuate the increase in NAc extracellular DA elicited by chemical stimulation (with 5 mM NMDA) of the ventral subiculum of the hippocampus. The stimulation of the vSub during perfusion of artificial cerebrospinal fluid in NAc induced a significant and persistent increase in NAc DA levels. Reverse dialysis of 0.05 mM acamprosate in NAc blocked the increase in DA evoked by the chemical stimulation of the vSub. These data support the possibility that the antagonism at the NMDA receptors in NAc can explain, at least in part, the mechanism of action of this drug.

Local acamprosate modulates dopamine release in the rat nucleus accumbens through NMDA receptors: an in vivo microdialysis study.

The effects of acamprosate on the in vivo dopamine extracellular levels in the nucleus accumbens and the involvement of N-methyl-D-aspartate (NMDA) receptors in these effects were investigated. Microdialysis in freely moving rats was used to assess dopamine levels before and during simultaneous perfusion of acamprosate and/or different agonists or antagonists of NMDA receptors. Perfusion with acamprosate at concentrations of 0.5 and 5 mM provoked a concentration-dependent increase in extracellular dopamine in nucleus accumbens. The lowest concentration of acamprosate assayed (0.05 mM) had no effect on dopamine levels. Infusion of NMDA (25 and 500 microM) and the glutamate uptake blocker, L-trans-pyrrolidine-2,4-dicarboxilic acid (PDC) (0.5 mM) into the NAc caused a significant increase in DA, whereas acamprosate (0.05 mM) co-infusion with these compounds blocked or attenuated the NMDA and PDC-induced increases in DA levels. Co-infusion of the selective antagonist of NMDA receptors, DL-2-amino-5-phosphonopentanoic acid (AP5) (400 microM) with acamprosate (0.5 mM), did not reduce the increase of DA levels induced by acamprosate. These results demonstrate that acamprosate is able to modulate DA extracellular levels in NAc via NMDA receptors and suggest that acamprosate acts as an antagonist of NMDA receptors.

Surgical management of retroperitoneal sarcomas associated with external and intraoperative electron beam radiotherapy.

AIMS: To report outcomes of adults with retroperitoneal sarcoma (RS) treated by surgery, external beam radiotherapy (EBRT) and intraoperative electron beam radiotherapy (IORT). METHODS: From July 1988 to February 2001; 24 patients with primary and recurrent RS were diagnosed and treated. The median dose and energy of IORT delivered was 15 Gy/9meV. EBRT dose varies between 45-50 Gy. RESULTS: There were five primary and 19 recurrent tumours. One primary and five recurrent tumours underwent R0 resection. There were 12 liposarcomas and 19 grade I tumours; 13 patients developed local recurrence and three developed distant metastases.Twenty-two patients received IORT associated with EBRT: 11 developed recurrences. Six patients developed Neurotoxicity (4 grade II and 2 grade III). Disease free survival and overall survival at 5 years was 28 and 56% respectively. CONCLUSIONS: EBRT with IORT treatment is a promising technique for local control. Lower recurrence rates are associated with radical (R0) surgical procedures.

A prospective and randomized study using ribavirin as monotherapy for the treatment of naïve patients with chronic hepatitis C.

In order to evaluate the response to ribavirin in previously untreated patients with chronic hepatitic C, 39 patients were selected for a double-blind prospective and randomized trial, and divided into two groups: ribavirin-group (19 patients) and placebo-group (20 patients). Ribavirin was administered orally for 24 weeks (600 mg/day, followed by 1,000 mg/day and 1,200 mg/day each one for 8 weeks). After 3 months of drug administration, the patients were evaluated by measuring biochemical, virologic and histologic responses. After this phase, ribavirin was offered to the patients who had received placebo (second phase). The results showed that the patients who received ribavirin showed a higher reduction in serum alanine aminotransferase (ALT) activity than patients in the placebo group. Among the patients in the ribavirin-group, a complete biochemical response (ALT levels normalized) was observed in 3 patients (16%), and a partial response (reduction greater than 50% of the initial value of ALT activity) in 4 (21%). In the 20 patients in the placebo group, only 1 showed a partial response (5%). In the second phase of the study, among 16 patients who received ribavirin, 4 (25%) showed a complete and 5 (31%) a partial biochemical response. HCV-RNA did not become negative in any patient during the two phases. A reduction in the score of portal and lobular activity was observed in patients who received ribavirin, but statistical analysis did not identify differences. This study showed that ribavirin alone induces a biochemical response (ALT reduction) in some patients with chronic hepatitis C, which may be associated with a reduction in hepatic inflammatory activity reduction, but the changes are not sufficient to recommend initial monotherapy with ribavirin.

[The tobacco industry's internal documents and smoking prevention in Spain]. / Los documentos internos de la industria tabaquera y la prevención del tabaquismo en España.

A 1998 agreement between several states in the USA and the tobacco industry made millions of pages of internal documents available to the public. Many of these documents contain information that the industry would have preferred to keep confidential. Systematic review of these internal documents constitutes a valuable resource for international tobacco control, since they are available on the Internet and can be accessed from anywhere in the world. These documents provide relevant and useful information to antismoking activists and researchers. To facilitate their use, the present article presents the electronic archives of the tobacco industry's documents, describes methods for conducting searches, and identifies the documents with information on the industry's tactics for manipulating Spanish politics and society for its own commercial interests during the 1970s, 1980s, and 1990s.

[Differences in the release of omeprazole in 4 commercial preparations: influence of pH and ionic concentration]. / Diferencias en la liberación de omeprazol en cuatro preparados comerciales: influencia del pH y la concentración iónica.

The influence of exposition to different ionic concentrations and pH values on the subsequent in vitro dissolution of omeprazole at pH 6.8 was studied in four enteric-coated commercial formulations. Assays were done using an experimental protocol similar to that recommended in Delayed-Release (Enteric Coated) Articles-General Drug Release Standards (USP 23) slightly modified to achieve similar pH values to commonly observed in patients under omeprazole treatment. Omeprazole capsules were exposed during 1 or 2 hours to four different pH values: 4.8, 5.0, 5.2, and 5.4 and two NaCl concentrations: 75 and 225 mM. After that, dissolution tests at pH 6.8 were performed. Three formulations (Emeprotón, Pepticum and Ulceral) released different percents of the encapsulated dose at the above acidic mediums and, consequently, the omeprazole dissolved underwent a remarkable degradation. The drug contained in the enteric-coated granules of Losec was not released and therefore the amount of omeprazole dissolved at pH 6.8 from Losec capsules was higher than the obtained with the other three preparations tested.

Computed tomography-guided fine-needle aspiration biopsy.

The therapeutic and prognostic evaluation of malignant neoplasias depends largely upon a precise morphologic diagnosis. Several papers have focused on the importance of fine-needle aspiration under computed tomography guidance in the diagnosis of unresectable neoplasms and in the investigation of metastases. The objective of this study is to evaluate the diagnostic accuracy, the sensitivity, and the negative predictive value obtained with the technique. Fine-needle aspiration cytology (FNAC) was performed on 207 patients, with a total of 210 cases, from 1991 to 1994, under computed tomography (CT) guidance. There were 128 (61.8 percent) males and 79 (38.2 percent) females with a mean age of 41 years (range 1 to 91 years). Lung and liver were the most frequent anatomic sites. The analysis of this material disclosed 41 cases with cytological diagnosis of negative for malignancy (19.52 percent), and in 131 (62.38 percent), the diagnosis was positive. It was possible to define the cytologic lineage in 54 percent of the cases. The diagnosis in 14 (6.67 percent) cases was suspicious for malignancy, and in 24 (11.43 percent) cases the material was insufficient for the cytologic diagnosis. Of the 210 cases, 106 showed histological diagnosis and/or clinical follow-up. Forty-seven (44.3 percent) had histological diagnosis before the FNAC and 50 cases (56.7 percent) histological diagnosis after the procedure. The comparison between cytological and histological diagnosis showed a sensibility of 80.4 percent, specificity of 100 percent, positive predictive value of 100 percent and negative of 16.7 percent. The efficiency of the test was 81.1 percent. This study showed that FNAC, under computed tomography guidance, is a sensitive and specific technique for the diagnosis of deep-seated lesions.

[Solid cystic tumor of the pancreas. Case report]. / Tumor sólido-cístico de pâncreas. Relato de caso.

The solid and cystic tumour of the pancreas is a rare entity that occurs in young women. Clinically the patients are often asymptomatic, the tumor of variable size (2-10 cm) and show a fibrous encapsulation. In contrast to adenocarcinoma of pancreatic ductal cells, which is the most frequent tumor of the pancreas, this tumour have a slow growth, usually do not have metastases and have a favourable prognosis. The authors related the case and have done a revision of the illness.

[Study of preoperative risk factors for bacteriobilia in patients with acute calculosis cholecystitis]. / Estudos dos fatores de risco pré-operatórios para bacteriobilia em doentes portadores de colecistite aguda calculosa.

OBJECTIVE: to determine an association between the preoperative clinical status and the result of bile and gallbladder wall cultures. MATERIAL AND METHODS: 28 variables regarding history, physical examination and labatorial assessment in 38 patients with acute calculosis cholecystitis submitted to urgency surgery were prospectively studied during a 19-month period, between November 1995 and May 1997. Cultures for aerobic and anaerobic agents from both the gallbladder wall and the bile were performed, in three different culture media (BACTEC 9240, BHI and HEMOBAC). RESULTS: bacteria were isolated in at least one culture medium, in 68.2% of the patients. At univariate analysis, five preoperative factors were identified as predictors of bactibilia: over 55 years of age, a greater than 0.4 degrees C difference in the axillary-rectal temperature, a greater than 12.000 cels/m3 blood leukocyte count, a greater than 75% neutrophil percentage and a greater than 4% rod neutrophil percentage. Owing to the small sample size, statistical significance of the series could not be noted by logistic regression, although a trend to preoperative determination could be observed in 98% of the subjects with positive culture, by means of the model based on age and percentage of rod neutrophil. By analyzing predictive factors jointly, it was noted that patients with more than one predictive factor have a significantly greater possibility to yielding positive culture when compared to those with up to one predictive factor for bactibilia. CONCLUSIONS: We concluded that, in patients with acute calculosis cholecystitis, bactibilia may be predicted yet at the preoperative period, by using simple and easily obtained data.

Evidence of a flip-flop phenomenon in acamprosate pharmacokinetics: an in vivo study in rats.

The pharmacokinetics of acamprosate were examined in the rat after oral and intravenous administration in order to detect the possible presence of a flip-flop phenomenon. Rats received 9.3 or 73.3 mg/kg of the drug as an intravenous bolus. The same doses were orally administered via gastric intubation. Plasma samples were taken from the jugular vein for determination of acamprosate concentration by liquid scintillation counting. The drug content was also quantified in urine and faeces. The acamprosate bioavailability was close to 20%, the amount recovered in the faeces being around 80% of the administered dose. The terminal slope of the oral plasma curve was significantly lower than that obtained after intravenous administration of the drug at both doses tested (p<2 x 10(-6) in both cases). Moreover, the downward slope after oral administration (lambda2=0.006 +/- 0.001 min(-1)) practically coincided with the first-order absorption rate constant, previously reported by us, obtained using an in situ rat gut technique. It is concluded that the acamprosate absorption rate is considerably slower than its elimination rate so that the drug exhibits flip-flop pharmacokinetics after oral administration. The lower intrinsic first-order absorption rate constant, ka, is responsible for this phenomenon.

Tomographic evaluation of size and X-ray density of normal and denervated human muscles.

Neuromuscular disease will lead to size changes, degeneration or destruction of muscle fibres. However, fat or connective tissue infiltration occurs and this prevents the use of simple measures to assess wasting. Computerized tomography will allow accurate assessment of this wasting. Five normal subjects and five patients with total traumatic denervation of radial or peroneal origin were examined. Denervated muscle was shown to have lower than normal cross-section and X-ray density. These reductions were not paralleled in circumference or limb volume. Recovery could be followed by tomography.

Low bioavailability of amoxicillin in rats as a consequence of presystemic degradation in the intestine.

Several studies have been carried out to elucidate the causes of the low oral bioavailability of amoxicillin in rats. The hepatic first-pass effect of the antibiotic was estimated by comparing the area under the plasma drug concentration-versus-time curve from time zero to infinity (AUC0-infinity) obtained after injecting the drug into a mesenteric vein with the AUC0-infinity value obtained after injecting the drug into the jugular vein of conscious rats. No hepatic first-pass effect was detected. The bioavailability of amoxicillin after intraduodenal administration was only 51%, and the fraction of the dose remaining in the intestine at the end of the experiment was 4.5%. This was far less than the fraction that did not reach systemic circulation, which indicates a presystemic loss of drug, probably at the intestine. In vitro studies corroborated the fact that amoxicillin is subjected to presystemic degradation by intestinal juices and intestinal tissues. The greatest loss of drug occurred in the complete intestine (45% of the initial amount), and it was mainly due to the action of intestinal tissues (28% of the initial amount) but was also due to the action of intestinal juices (15% of the initial amount). The absorption of amoxicillin in three parts of the intestine (upper, middle, and lower) was also evaluated. The largest AUC0-infinity value and the highest plasma drug levels were obtained when amoxicillin absorption took place in the middle intestine. The smallest AUC0-infinity value and the lowest plasma drug levels corresponded to absorption from the upper intestine.

Studies on the renal excretion mechanisms of cefadroxil.

The mechanisms of renal excretion of cefadroxil were investigated in conscious rats. The drug was intravenously infused at several infusion rates (0.27, 1.08, 5.40, 12.00, and 31.35 mg/hr), and the total and renal clearances were determined after the steady-state was reached. Renal clearance accounted for approximately 91% of total clearance. Renal clearance of cefadroxil increased from 2.51 +/- 0.39 to 3.57 +/- 0.43 ml/min as the steady-state cefadroxil plasma concentration increased from 1.7 +/- 0.3 to 24.4 +/- 3.8 micrograms/ml, and this has been attributed to a saturable renal tubular reabsorption of the antibiotic. The ratio of unbound cefadroxil renal clearance to glomerular filtration rate was larger than unity, which indicates that the antibiotic also undergoes active renal tubular secretion. When cefadroxil was administered together with cephalexin, an increase in the renal clearance of cefadroxil was observed, which has been attributed to a competitive inhibition of the tubular reabsorption of cefadroxil by cephalexin. A pharmacokinetic model for the renal excretion of cefadroxil was developed, and mathematical expressions showing the relationship between renal clearance and steady-state plasma concentration were deduced.