Disposition of [3H]flobufen and its active metabolite in rats

The present authors investigated the excretion, distribution and pharmacokinetics of the novel potential antirheumatic agent flobufen and its active metabolite after p.o. and i.v. doses of 2, 10 and 50 mg/kg administered to rats. The drug is resorbed well from the digestive tract and mostly it is metabolized to the principal metabolite M, which is only slowly excreted from the organism mainly by renal clearance. Within the whole dose range the kinetics of the drug is linear. Binding of flobufen and M to proteins is high (95-99%). The highest concentrations of radioactive metabolites (mostly M) were found in the plasma, liver, lungs, kidneys, connective tissue and inflammatory foci. The penetration of metabolites through the placenta and excretion in human milk are relatively important.     

Contribution of hypoxia-measuring molecular imaging techniques to radiotherapy planning and treatment

Hypoxia is related to poor prognosis because it is associated to chemo-and radioresistance. During recent years the evolution of imaging methods like PET/CT and MRI has meant the appearance of new perspectives with direct implications in radiation therapy. We discuss previous experiences in staging, planning and in the follow-up process with these techniques for measuring tumour hypoxia.     

Lindane inhibition of [35S]TBPS binding to the GABAA receptor in rat brain.

The inhibition of [³⁵S]t-butylbicyclophosphorothionate ([³⁵S]TBPS) binding to the GABA_A receptor by the insecticide γ-hexachlorocyclohexane, lindane, was studied in several brain regions and using different membrane preparation methods, both in vitro and after dosing the animals with the chemical. In the latter studies, the amount of lindane remaining in the membrane suspensions used for binding assays was determined. In vitro data showed values of IC₅₀ from 150 to 1675 nM, varying in function of the membrane preparation method used. This may account for the discrepancies in IC₅₀ values found in the literature. IC₅₀ values within the range of 150–250 nM were determined using extensively washed membranes from several brain regions, so no evidence arose for brain regional differences in the affinity of lindane for the TBPS binding site. After different schedules of acute treatment with lindane, we found a manifest relationship between the extent of the observable inhibition of [³⁵S]TBPS binding and the lindane amount remaining in the membrane suspensions used for binding assays. This relationship was in good agreement with the in vitro data, so no support for an in vivo acute regulation of the binding site was obtained.     

Enhanced neurotoxicity of 3,3'-iminodipropionitrile following carbon tetrachloride pretreatment in the rat.

The consequences of 3,3'-iminodipropionitrile (IDPN) exposure in animals merits attention both because of its unique neurotoxic effects and as a potential model compound of human dyskinetic disorders. An important question that remains to be determined is whether IDPN itself or a putative active metabolite is responsible for the neurotoxic actions of the chemical in vivo. The present work tested the hypothesis that IDPN must be metabolized by the liver to an active metabolite to become neurotoxic. Thus a reduction in IDPN neurotoxicity would be expected when liver function is compromised. Male Long-Evans rats were given ip injections of saline, 100 (IDPN1) or 200 (IDPN2) mg/kg of IDPN for three days. Half of the animals in each IDPN dose group received corn oil po and the other half 1 g/kg of the hepatotoxicant carbon tetrachloride (CCl4) for three days, starting one day before IDPN administration. Body weights were obtained regularly after exposure. Horizontal and vertical motor activity, and acoustic startle response were monitored prior to, and 1,3,9 and 16 weeks after IDPN exposure. An observational rating score was obtained at 1, 3 and 9 weeks. Auditory thresholds for 5- and 40-kHz tones were estimated by reflex modification procedures at 10 weeks. Animals receiving IDPN2 alone displayed the overt behavioral signs characteristic of IDPN intoxication (postural disturbances, head dyskinesias, backward walking, circling, increased motor activity, and decreased startle response). They also showed weight loss, hyperactivity, a transient rearing deficit, decreased startle amplitudes and elevated auditory thresholds for low- and high-frequency tones. None of these symptoms were observed in the animals treated with CCl4 alone, and only a mild transient effect on the observational rating score was shown by the IDPN1 alone animals. In contrast, IDPN1/CCl4 resulted in the same or higher toxicity than the IDPN2 treatment. IDPN2/CCl4 resulted in severe toxicity (38% mortality over a two-week period) and enhanced body weight and behavioral effects compared to IDPN2 alone group. Impairment of xenobiotic biotransformation was confirmed by elevated pentobarbital sleeping time in animals under the same CCl4 dosing regimen. In conclusion, pretreatment with hepatotoxic dosages of CCl4 leads to increased toxicity of IDPN. This suggests that hepatic transformation of the chemical is not required for the manifestation of IDPN-induced neurotoxicity, but instead may be involved in the detoxification of this compound.     

Increase in the isolation-induced social behavioural deficit by agonists at 5-HT1A receptors

The effect of 5-HT1A agonists was studied in the isolation-induced social behavioural deficit test. The drugs 8-OH-DPAT (0.125 mg/kg), buspirone (16 mg/kg) and ipsapirone (8 mg/kg) further increased the deficit. Unlike 8-OH-DPAT, the other two drugs may act non-specifically since they reduced spontaneous motor activity at 16 mg/kg, as measured in an activity meter. In addition, 8-OH-DPAT (0.25 mg/kg), buspirone (8 mg/kg) and ipsapirone (8 mg/kg) decreased exploratory activity in the open-field test. Since the smallest active doses were very close in the behavioural deficit and in the open-field tests, it is suggested that a common phenomenon, increased emotionality or reactivity, sustained both these reductions in activity. The increase in the behavioural deficit induced by 8-OH-DPAT, was likely to have resulted from stimulation of 5-HT1A receptors, since it was impaired by pretreatment with penbutolol, a beta-adrenergic-blocking drug, also known to bind to 5-HT1 receptors. Since it was previously shown that the behavioural deficit was reduced by agonists at 5-HT1B receptors, it is proposed that the behavioural inhibition, resulting from an isolation-induced increase in reactivity is bi-directionally modulated by serotonergic drugs, where 5-HT1A agonists increase and 5-HT1B agonists decrease this inhibition.     

Changes in diastolic function in heart rejection: role of Doppler echocardiography]

In acute cardiac rejection, left ventricular diastolic function is altered. To study these abnormalities and their utility in cardiac allograft rejection, we studied 56 cardiac transplant recipients. All patients were assessed with endomyocardial biopsy and Doppler echocardiography done in the same day. A total of 163 Doppler studies were recollected. Cardiac transplant recipients were excluded during the early 6 weeks postoperative period. Totally, 100 biopsies were normal, 48 positive for mild rejection (Billingham Gde I-II) and 15 positive for moderate or severe rejection (Billingham Gde III-IV). Compared to negative biopsies, during acute rejection left ventricular wald thickness significantly increased (p < 0.05); isovolumic relaxation period and pressure half-time significantly decreased (p < 0.05, p < 0.001 respectively). Nevertheless, increase in peak early mitral flow velocity was only significantly associated with severe rejection (p < 0.001). Correlating only progressive shortening of isovolumic relaxation period parameter in the diagnosis of graft rejection, we forward a high sensibility (85%) and low specificity (57%). Thus, Doppler echocardiographic evaluation of left ventricular diastolic function provides a non-invasive tool for early detection of acute rejection monitoring after the early postoperative period.     

Bacterial DNA in patients with cirrhosis and sterile ascites. Its role as a marker of bacterial translocation and prognostic tool]

During the last decade, we have witnessed an increase in the amount of data related with the presence of bacterial translocation in experimental models of cirrhosis. However, clinical studies have been limited by the lack of non-invasive methods to study this phenomenon. Over the past years, the research developed in our laboratory has been focused on the detection of bacterial DNA in serum and ascitic fluid of patients with cirrhosis and sterile ascites, the clinical and immunological implications of such finding. Initially, by means of a polymerase chain reaction (PCR)-based method and automated nucleotide sequencing, we were able to detect and identify the presence of fragments of bacterial DNA in the mentioned patients with culture-negative, non-neutrocytic ascites. Since then, we have accumulated a core of data suggesting that the presence of bacterial DNA may have an important role not only as a marker of bacterial translocation, but also as a short-term prognostic factor. Here, we discuss the past, present and future of this line of investigation.     

Prognostic and immunohistochemical validation of the capella classification of pancreatic neuroendocrine tumours: an analysis of 82 sporadic cases

AIMS: To study the clinical outcome of 82 cases of pancreatic neuroendocrine tumours classified according to the recent histological and prognostic classification of Capella. METHODS AND RESULTS: Eighty-two surgical cases of pancreatic neuroendocrine tumours were examined histologically with immunohistochemical staining of paraffin sections using streptavidin-biotin complex and application of antibodies against chromogranin A and 10 hormonal peptides. Classification in four groups correlated with long follow-up and outcome of these cases. Histological examination showed 30 group I, four group II, 41 group III and seven group IV tumours. Twenty-one (70%) of group I tumours were insulinomas, whereas 25% of group III tumours were glucagonomas and 25% were unclassified. Most group IV tumours were unclassified, showing no immunohistochemical staining with any of the 10 hormonal peptides tested. Outcome was clearly correlated with tumour group. Among the 14 patients who died of the disease, four had group IV and 10 group III tumours. Thus, unclassified asymptomatic tumours without immunohistochemical staining had a poorer prognosis than asymptomatic tumours with staining. CONCLUSION: This study validates the Capella classification as easy to apply and useful in predicting clinical outcome.     

Regional distribution of a high-affinity enkephalin-degrading peptidase ('enkephalinase') and effects of lesions suggest localization in the vicinity of opiate receptors in brain.

The distribution of a high affinity enkephalin-dipeptidylcarboxypeptidase between regions of mouse brain is markedly heterogenous and parallels that of opiate receptors. Furthermore intrastriatal administration of kainic acid as well as interruption of the nigrostriatal dopaminergic pathway by 6-hydroxydopamine (6-OHDA) lead to similar decreases in this peptidase activity and in the number of opiate receptors. On the contrary, no correlation was found between low affinity enkephalin degrading enzymes and opiate receptors.