Coupled plasma filtration-adsorption in Weil's syndrome: case report.

Weil's syndrome is a form of leptospirosis characterized by jaundice, renal failure and hemorrhagic diathesis. Its pathogenesis is related with the invasiveness of leptospires and with the subsequent systemic inflammatory response. Coupled plasma filtration-adsorption (CPFA) is a modality of extracorporeal blood purification in which plasma is separated from the whole blood and directed into a sorbent cartridge. Due to the ability of the sorbent agent to remove cytokines, CPFA has been proposed as an adjuvant treatment in septic shock. We report the case of a 27-year-old man with Weil's syndrome who was admitted to ICU with hypotension and anuria refractory to fluid therapy, ARDS, and hepatic involvement. The man needed intubation, mechanical ventilation and vasopressor infusion. CPFA was started early after the onset of shock. Five courses of CPFA were performed. Each course lasted for 10 h with 14 h interval. Weaning from vasopressors was achieved during the second course of CPFA (day 2 after admission). Weaning from ventilation was achieved on day 6. Interestingly, diuresis started during the first course of CPFA, with a creatinine clearance of 63 ml/min on day 8 and a normalization of the ratio urinary to plasma osmolality on day 28. The patient was discharged on day 11 and 28 from the Intensive Care Unit and hospital respectively.

Binding of paroxetine to the serotonin transporter in membranes from different cells, subcellular fractions and species.

The binding of [(3)H]-paroxetine to membrane serotonin transporter (SERT) has been studied in membranes from different sources and subcellular fractions. From rat were membranes from venous blood platelets, brain total cortex, brain microsomes, brain crude and purified synaptosomes. Membranes were obtained from venous blood platelets from human volunteers and from brain cortex tissue from neurosurgery (cerebral lobectomies following craniocerebral injuries). The main finding was that the K (D) of paroxetine binding to the SERT was the same for platelet and nerve ending (synaptosomal) membranes. That parameter was significantly lower in membranes from brain microsomes and cortex total tissue. No species related difference was found, where comparison was possible, between human and rat tissue. The equality of K (D) of paroxetine binding to blood platelet membranes and to membranes from nerve endings appears to encourage the use of such membranes as a model for brain SERT. Binding at two different temperatures for several of the fractions suggests that paroxetine-SERT interaction is entropy-driven.

Sex differences in human lymphocyte Na,K-ATPase as studied by labeled ouabain binding.

Lymphocytes Na,K-ATPase is a plasma membrane enzyme that is up-regulated under lymphocytes activation. It is also studied as a model of brain cells Na,K-ATPase. Data about sex-related specificities of the enzyme are not available. The binding of tritium-labelled ouabain to lymphocyte plasma membrane Na,K-ATPase was studied in healthy volunteers of both sexes. The binding interactions were expressed in terms of K(D) and B(Max). The first parameter is related to the affinity of ouabain for the enzyme whereas the second one is related to its density on the cell membrane. Distinct sex-related differences were found. Whereas in males there is a significant direct correlation between the parameters K(D) and B(Max), in females this is not present. However, in females there is a significantly lower K(D) in the 25-37 age range. The latter result probably reflects the expression of subunit variants giving a greater affinity for ouabain. This circumstance may be relevant both to lymphocytes' ability to be activated and to brain function, if one admits that lymphocyte Na,K-ATPase faithfully represents the brain-borne one.

Abnormalities of Na/K ATPase in migraine with aura.

It has been previously shown from our laboratory that abnormal functioning of Na/K ATPase can cause spreading depression, the likely mechanism of migraine aura. We used lymphocytes to investigate whether or not membrane Na/K ATPase is altered in migraine with aura patients. Lymphocytes were prepared from such patients, aged 20-45 years, and from age-matched healthy volunteers (controls). The binding of 3H- ouabain was studied using increasing concentrations (0.5-25 nm) of this radioligand, specific for Na/K-ATPase. We studied 19 migraine with aura patients and 22 healthy volunteers, matched for age and sex. B(max) (fmol/mg protein) and K(D) (nM) were not different between patients and controls. However, their ratio (B(max)/K(D)) was higher in patients than in controls. B(max) was (mean +/- SD) 270 +/- 110 fmol/mg protein in controls, and 360 +/- 230 in migraine with aura patients (P = 0.10, t-test). K(D) was (mean +/- SD) 2.8 +/- 1.5 nm in controls, and 2.9 +/- 3.2 nm in migraine with aura patients (P = 0.88, t-test). B(max)/K(D) was (mean +/- SD) 120 +/- 78 in controls, and 210 +/- 190 in migraine patients (P = 0.046, t-test). Moreover, no control patient had a B(max)/K(D) ratio greater than 398, while three migraine patients had ratios of 417, 572 and 722, respectively. Ouabain binding is affected by Na/K ATPase structure (K(D)) and expression (B(max)). While these parameters were not altered in migraine with aura patients, the difference in their ratio suggests an imbalance between the enzyme's ouabain affinity and its expression, with higher-affinity subtypes being more expressed than normal. Moreover, single patients had values quite different from the control population. Our data suggest that (i) ouabain binding to lymphocyte membranes may be a useful tool in the diagnosis of migraine with aura and (ii) Na/K ATPase abnormalities may be involved in migraine aura.

The creatine transporter mediates the uptake of creatine by brain tissue, but not the uptake of two creatine-derived compounds.

Hereditary creatine transporter deficiency causes brain damage, despite the brain having the enzymes to synthesize creatine. Such damage occurring despite an endogenous synthesis is not easily explained. This condition is incurable, because creatine may not be delivered to the brain without its transporter. Creatine-derived compounds that crossed the blood-brain barrier in a transporter-independent fashion would be useful in the therapy of hereditary creatine transporter deficiency, and possibly also in neuroprotection against brain anoxia or ischemia. We tested the double hypothesis that: (1) the creatine carrier is needed to make creatine cross the plasma membrane of brain cells and (2) creatine-derived molecules may cross this plasma membrane independently of the creatine carrier. In in vitro mouse hippocampal slices, incubation with creatine increased creatine and phosphocreatine content of the tissue. Inhibition of the creatine transporter with 3-guanidinopropionic acid (GPA) dose-dependently prevented this increase. Incubation with creatine benzyl ester (CrOBzl) or phosphocreatine-Mg-complex acetate (PCr-Mg-CPLX) increased tissue creatine content, not phosphocreatine. This increase was not prevented by GPA. Thus, the creatine transporter is required for creatine uptake through the plasma membrane. Since there is a strong indication that creatine in the brain is mainly synthesized by glial cells and transferred to neurons, this might explain why hereditary transporter deficiency is attended by severe brain damage despite the possibility of an endogenous synthesis. CrOBzl and PCr-Mg-CPLX cross the plasma membrane in a transporter-independent way, and might be useful in the therapy of hereditary creatine transporter deficiency. They may also prove useful in the therapy of brain anoxia or ischemia.

Successful treatment of epilepsy with serotonin reuptake inhibitors: proposed mechanism.

The widely used antidepressants Specific Serotonin Reuptake Inhibitors (SSRI) have been tried with success as anticonvulsants in cases of nonsymptomatic epilepsy. This attempt was performed on the basis of experimental data suggesting the involvement of impairments of the serotonin system in the genesis of epilepsy. This overview summarizes the clinical data and presents biochemical and neurochemical evidences suggesting the mechanism of the therapeutic effects of SSRI in nonsymptomatic epilepsy. In particular, studies on blood-borne neutral amino acids and platelet serotonin transporter (SERT) in epileptics suggest: (a) That a decreased brain availability of tryptophan may be related to some types of epilepsy. (b) That reduction of the density of SERT may be a homeostatic reaction in the brain following epileptic seizures.

Ethanol inhibits the binding of substance P to rat brain cortex NK1 receptors.

The binding of 125I-labeled substance P (SP) to rat brain cortex membranes has been studied under control conditions and in the presence of ethanol. The binding of SP at low concentrations (20-1000 pM) gave two components, one with a KD value of 80 pM and another one with a KD of 500 pM. The higher-affinity component is due to NK1 receptors, as confirmed by the inhibition of the SP binding by the rodent NK1 specific agonist [Sar9 Met(O2)11]SP. Ethanol (1.7 mM) added to the binding assays inhibited by more than 50% the specific binding at a very low SP concentration (20 pM); however, it had no effect at SP concentrations ranging from 50 to 120 pM. This suggests a decrease by ethanol of the affinity of SP to the NK1 receptors involved in this binding component. The ethanol effect disappeared at [EtOH] < or = 0.17 mM.

Subfractionation of ficoll gradient purified synaptosomes: GABA uptake by the subfractions.

The classical synaptosomes preparation purified on discontinuous Ficoll gradient has been sufractionated into three further subfractions by introducing more Ficoll density layers. Among the three subfractions, the lightest one was the one which was more difficult to obtain in reproducible amounts and was only partially characterized in terms of labelled GABA uptake. The heaviest one most probably is largely made up of partially damaged nerve endings. The central one was the most reproducible in terms of yield and labelled GABA uptake and actually was the one we studied more thoroughly in terms of morphology, labelled GABA uptake and its pharmacology. A comparison has been made with the classical "total" purified synaptosomes fraction. An interesting result of these experiments is a paradoxical effect of the glial uptake inhibitor beta-alanine. This substance appears to favor, in both "total" and "central" fraction synaptosomes, a redistribution of taken up GABA from contaminating glia to actual nerve endings.

GABA uptake by rabbit restiform body homogenates.

Restiform body (inferior cerebellar peduncle) preparations were obtained from rabbit brain stem slices and homogenized. When challenged with labelled GABA, these homogenates took it up briskly. We have characterized pharmacologically this uptake which resulted almost equally neuronal and glial. The neuronal component of the GABA uptake might be due to the adjacent cochlear nuclei coming along in the preparations, whereas the glial component probably belongs to the restiform body proper. Another possibility is that actually both components are due to the myelinated fibers and glia which make up the restiform body.

Pretreatment of rat brain synaptosomes with GABA increases subsequent GABA uptake via GABA(B) receptor activation.

Pretreatment with 100 microM GABA of synaptosomes purified from rat brain results in an increased uptake of the labelled neurotransmitter in subsequent incubations. The effect is blocked by a GABA(B) receptor antagonist, 2-hydroxy-saclofen. The effect is mimicked by baclofen and the baclofen effect is blocked by saclofen too. Lower GABA concentrations (up to 50 microM) do not result in an increase of subsequent GABA uptake. Treatment of synaptosomes with 8-Br-cAMP results in a decreased GABA uptake. Since the uptake incubations were run with saturating concentrations of labelled GABA, the data indicates that GABA(B) receptor activation in brain synaptosomes up-regulates their GABA uptake capacity by an increase in Vmax. This mechanism appears of physiological relevance under conditions of sustained GABA release and substantial increase of its extracellular concentration.

A subtype of the gamma-aminobutyric acid(B) receptor regulates cholinergic twitch response in the guinea pig ileum.

The pharmacological profile of the gamma-aminobutyric acid (GABA)(B) receptor regulating cholinergic twitch contraction in the guinea pig ileum myenteric plexus-longitudinal muscle preparation was investigated. GABA and (-)-baclofen inhibited the contraction, exhibiting quite close potencies (pD(2) for GABA = 5.70; pD(2) for (-)-baclofen = 5.33). The compound CGP 47656 also reduced the cholinergic twitch concentration (pD(2) = 5.42), but its efficacy was significantly lower than that of (-)-baclofen or GABA. Added at varying concentrations, CGP 47656 modified the concentration-response curve of (-)-baclofen as expected for a partial agonist. Phaclofen, CGP 36742, CGP 35348, and CGP 52432 behaved as competitive antagonists of (-)-baclofen, exhibiting the following pA(2) values: 3.90, 4.88, 5.02, and 7.82, respectively. The compound CGP 56999 behaved as a potent noncompetitive GABA(B) receptor antagonist. In comparing the pharmacological profile of the ileal receptor with those of the previously characterized pharmacological subtypes of the GABA(B) receptor present in the central nervous system, it can be seen that the GABA(B) receptor inhibiting cholinergic twitch contraction in guinea pig ileum myenteric plexus-longitudinal muscle mostly resembles the receptor located on somatostatin human neocortex nerve terminals.

[A propofol-ketamine combination in short-term anesthesia]. / Associazione propofol-ketamina nelle anestesie di breve durata.

The authors report the results of a study in 43 patients anesthetized using Propofol + Ketamina. The results seem to stage that the two drugs have complementary effects. Propofol and Ketamina used together and infused inravenously have given better results, and less kinds of complementary effects than usual techniques.