Modeling tardive dyskinesia: Predictive 5-HT2C receptor antagonist treatment

Tardive dyskinesia (TD), a movement disorder produced by long-term treatment with a classical antipsychotic drug, is generally considered to be a disorder of dopamine (DA) systems, since classical antipsychotics are potent DA D(2) receptor blockers. Also, acute DA D(1) agonist treatment of rats is known to produce vacuous chewing movements (VCMs), a behavioral feature resembling the oral dyskinesia that is so prominent in most instances of TD. In this paper we outline a series of studies in a new animal model of TD in which DA D(1) receptor supersensitivity was produced by neonatal 6-hydroxydopamine (6-OHDA) -induced destruction of nigrostriatal DA fibers. In rats so-lesioned 5-HT receptor supersensitivity is additionally produced, and in fact 5-HT receptor antagonists attenuate enhanced DA D(1) induction of VCMs. Moreover, in 6-OHDA-lesioned rats treated with haloperidol for one year, there a 2-fold increase in numbers of VCMs (vs intact rats treated with haloperidol); and this high frequency of VCMs persists for more than 6 months after discontinuing haloperidol treatment. During this stage, 5-HT(2) receptor antagonists, but not DA D(1) receptor antagonists, attenuate the incidence of VCMs. This series of findings implicates the 5-HT neuronal phenotype in TD, and promotes 5-HT(2) receptor antagonists, more specifically 5-HT(2C) receptor antagonists, as a rational treatment approach for TD in humans.     

Histamine H3 receptor ligands modulate L-dopa-evoked behavioral responses and L-dopa-derived extracellular dopamine in dopamine-denervated rat striatum

To explore a recently established association between histaminergic and dopaminergic neuronal phenotypic systems in brain, we determined the effect of the respective histaminergic H(3) receptor agonist and antagonist/inverse agonist, imetit and thioperamide, on L-DOPA - derived tissue and extracellular DA and metabolite levels in the striatum of 6-hydroxydopamine (6-OHDA) - lesioned rats (i.e., parkinsonian rats). We also examined the influence of histamine H(3) ligands on L-DOPA evoked behavioral responses (locomotor activity, number of rearings, stereotyped behavior and motor coordination). Using HPLC/ED and in vivo microdialysis technique imetit (5 mg/kg, i.p.) but not thioperamide (5 mg/kg, i.p.) was shown to attenuate an L-DOPA-evoked (15 mg/kg, i.p.; carbidopa, 30 min pretreatment) increase in extracellular DA in the neostriatum of 6-OHDA-lesioned rats. However, both imetit and thioperamide increased microdialysate levels of DOPAC and HVA, probably by enhancing intraneuronal DA utilization. As indicated by neurochemical analysis of the striatum imetit produced a decrease in tissue DA content. These findings support the hypothesis that central H(3) histaminergic receptors have a modulatory role in the storage, metabolism and release of DA derived from exogenous L-DOPA challenge. Furthermore, evidence from behavioral studies indicate that histamine H3 receptor blockade markedly improved motor coordination. Conversely, histamine H(3) receptor stimulation, being without effect on motor coordination, enhanced vertical activity in rats. From the above we conclude that the histamine H(3) agonism may augment motor dyskinesia in Parkinson's disease (PD) patients and presumably worsen L-DOPA therapy. Consequently, the histaminergic system represents a viable target for modulating the effectiveness of L-DOPA therapy in Parkinson's disease.     

Genetics of Lesch's typology of alcoholism

It is widely accepted that dopamine and serotonin (5-HT) neurotransmission can be critically involved in the development of alcohol abuse and alcohol dependence. Lesch's typology of alcoholism has been gaining increasing popularity as it qualitatively differentiates patients into different treatment response subgroups. The aim of the present study was to evaluate a possible genetic background of Lesch's typology with special emphasis placed on dopamine- and serotonin-related genes. 122 alcoholics (the mean age: 35+/-9 years) were investigated. According to Lesch's typology, 58 patients were of type I, 36 patients of type II, 11 patients of type III, and 17 patients of type IV. Alcohol drinking and family history was assessed by means of a structured interview, based on the Semi-Structured Assessment for the Genetics of Alcoholism. 150 control subjects without psychiatric disorders were also recruited. The control group was ethnically-, age- and gender-matched to the patients. The DRD2 TaqIA, exon 8, and promoter -141C ins/del polymorphisms as well as COMT Val158Met, 5HTT 44 bp del in promoter, and DAT 40 bp VNTR polymorphisms were detected by means of PCR. No significant differences were observed when the whole group of alcoholics and the controls were compared. Similarly, there were no differences between either the Lesch type I or type II alcoholics and the control subjects. No significant differences were observed between type I and type II alcoholics. Alleles frequencies were not calculated for the Lesch type III and type IV alcoholics since the number of patients was too small. The present results argue against any major role of the investigated polymorphisms in either Lesch type I or type II alcoholism. More comprehensive studies are needed to define the role of the investigated polymorphisms in Lesch type III and type IV alcoholism.     

Analysis of management of patients with multiple injuries of the locomotor system

Body injuries are very serious problems in industrialised countries and they are frequent causes of fatalities in our times. The variety and multiple combinations of body injuries are a challenge for the trauma team. On the basis of clinical and radiological documentation 315 patients with multiple injuries of the locomotor system (MILS) were included in the study. The criterion for inclusion of the patients into the study group was identification of MILS. The study showed that these injuries often involve young people (53%) (predominantly men) aged between 16 and 45 years. Road accidents were the most frequent cause of injuries —80.6%. MILS affected the lower limb in 49.,4%, upper limb in 33.2% and pelvis in 14.1%; 75% of the patients studied also suffered from concomitant injuries. The head and brain were involved in 92.9%, chest in 31.5% and abdomen in 21.3%. The mortality index for the population studied was 14%. An increasing value of the Injury Severity Score (ISS) or New Injury Severity Score (NISS) caused delay in surgical management of bone injuries and correlated with prolonged hospitalisation. Analysis emphasised the usefulness of the NISS as a valuable prognostic instrument in assessment of severity of injuries in patients with multiple injuries of the locomotor system.

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Résumé  Les traumatismes corporels sont un problème important dans les pays industrialisés et sont de nos jours une cause fréquente de mortalité. La variété et la multiplicité des combinaisons de traumatismes représentent une véritable difficulté pour les équipes trauma. 315 patients présentant un poly-traumatisme de l’appareil locomoteur (MILS) ont été inclus dans cette étude, le critère d’inclusion dans cette étude étant l’identification du poly-traumatisme. Cette étude a montré que ce type de traumatismes survient fréquemment chez une population relativement jeune (53%) avec une prédominance masculine entre 16 et 45 ans. La cause la plus fréquente de ces traumatismes est l’accident de circulation (80.6%). Les poly-traumatismes affectent les membres inférieurs dans 49.4% des cas, les membres supérieurs dans 33.2% des cas et le bassin dans 14.1% des cas. 75% des patients ont présenté par ailleurs des traumatismes combinés, têtes et encéphales dans 92.9% des cas, thorax 31.9% et abdomen dans 21.3% des cas. Le taux de mortalité pour cette population a été de 14% des cas. L’importance de la valeur des coefficients ISS ou NISS ont été une cause importante du retard à la prise en charge chirurgicale et ont également été un facteur de prolongation de l’hospitalisation. Cette analyse permet de mettre en évidence l’importance du coefficient NISS comme un instrument pronostic de la sévérité de tous les traumatismes survenant chez ces patients.

     

Amphetamine and mCPP Effects on Dopamine and Serotonin Striatalin vivo Microdialysates in an Animal Model of Hyperactivity

In the neonatally 6-hydroxydopamine (6-OHDA)-lesioned rat hyperlocomotor activity, first described in the 1970s, was subsequently found to be increased by an additional lesion with 5,7-dihydroxytryptamine (5,7-DHT) (i.c.v.) in adulthood. The latter animal model (i.e., 134 microg 6-OHDA at 3 d postbirth plus 71 microg 5,7-DHT at 10 weeks; desipramine pretreatments) was used in this study, in an attempt to attribute hyperlocomotor attenuation by D,L-amphetamine sulfate (AMPH) and m-chlorophenylpiperazine di HCl (mCPP), to specific changes in extraneuronal (i.e., in vivo microdialysate) levels of dopamine (DA) and/or serotonin (5-HT). Despite the 98-99% reduction in striatal tissue content of DA, the baseline striatal microdialysate level of DA was reduced by 50% or less at 14 weeks, versus the intact control group. When challenged with AMPH (0.5 mg/kg), the microdialysate level of DA went either unchanged or was slightly reduced over the next 180 min (i.e., 20 min sampling), while in the vehicle group and 5,7-DHT (alone) lesioned group, the microdialysate level was maximally elevated by approximately 225% and approximately 450%, respectively--and over a span of nearly 2 h. Acute challenge with mCPP (1 mg/kg salt form) had little effect on microdialysate levels of DA, DOPAC and 5-HT. Moreover, there was no consistent change in the microdialysate levels of DA, DOPAC, and 5-HT between intact, 5-HT-lesioned rats, and DA-lesioned rats which might reasonably account for an attenuation of hyperlocomotor activity. These findings indicate that there are other important neurochemical changes produced by AMPH- and mCPP-attenuated hyperlocomotor activity, or perhaps a different brain region or multiple brain regional effects are involved in AMPH and mCPP behavioral actions.     

Synthesis and cytotoxicity testing of novel 2-(3-substituted-6-chloro-1,1-dioxo-1,4,2-benzodithiazin-7-yl)-3-phenyl-4(3H)-quinazolinones

A new series of thirteen 2-[3-(substituted amino)-6-chloro-1,1-dioxo-1,4,2-benzodithiazin-7-yl]-3-phenyl-4(3H)-quinazolinones 4-16 were prepared in order to evaluate their cytotoxic activity against 12 human cancer cell lines. The bioassay indicated that the quinazolinone derivatives 5, 8-12, 15, and 16 possess cancer-cell growth-inhibitory properties. Compounds 5 and 12 showed a high level of selectivity for certain cell lines. The most active compounds 9, 10, 15, and 16 showed moderate antiproliferative activity and were approximately 4-fold less potent than cisplatin.     

No contribution of multipotent mesenchymal stromal cells to liver regeneration in a rat model of prolonged hepatic injury

Multipotent mesenchymal stromal (MS) cells from adult bone marrow are a cell population that can be expanded to large numbers in culture. MS cells might be differentiated toward hepatocytes in vitro and thus are promising candidates for therapeutic applications in vivo. The efficacy of bone marrow-derived MS cells versus hepatocytes to contribute to liver regeneration was compared in a rat model of prolonged toxic hepatic injury. Liver damage was induced by injection of carbon tetrachloride (CCl(4)) or allyl alcohol (AA) with and without retrorsine (R) pretreatment. MS cells or hepatocytes of wild-type F344 rats were injected into dipeptidyl peptidase IV (DPPIV)-deficient syngeneic rats. Hepatocyte chimerism was higher after intraportal hepatocyte transplantation in the R/AA group (mean maximal cluster size [MCS] = 21 cells) compared with the R/CCl(4) treatment group (MCS = 18). No hepatocyte engraftment was outlined following post-transplant CCl(4) injection only, whereas mere AA injection resulted in small clusters of donor-derived hepatocytes (MCS = 2). Intraparenchymal injection of hepatocytes was associated with a MCS = 11 after R/AA treatment and a MCS = 6 after AA administration alone. Redistribution of MS cells to the liver was shown after intraportal and intraparenchymal injection. In contrast to hepatocyte transplantation, however, donor-derived DPPIV-positive cells could not be demonstrated in any recipient after MS cell transplantation. Data from the present study indicate that a well-defined population of MS cells obtained according to established standard protocols does not differentiate into hepatocytes in vivo when transplanted under regenerative conditions, in which the application of hepatocytes results in stable hepatic engraftment.     

X-ray crystallography: Assessment and validation of protein-small molecule complexes for drug discovery

INTRODUCTION: Crystallography is the key initial component for structure-based and fragment-based drug design and can often generate leads that can be developed into high potency drugs. Therefore, huge sums of money are committed based on the outcome of crystallography experiments and their interpretation. AREAS COVERED: This review discusses how to evaluate the correctness of an X-ray structure, focusing on the validation of small molecule-protein complexes. Various types of inaccuracies found within the PDB are identified and the ramifications of these errors are discussed. The reader will gain an understanding of the key parameters that need to be inspected before a structure can be used in drug discovery efforts, as well as an appreciation of the difficulties of correctly interpreting electron density for small molecules. The reader will also be introduced to methods for validating small molecules within the context of a macromolecular structure. EXPERT OPINION: One of the reasons that ligand identification and positioning, within a macromolecular crystal structure, is so difficult is that the quality of small molecules widely varies in the PDB. For this reason, the PDB can not always be considered a reliable repository of structural information pertaining to small molecules, and this makes the derivation of general principles that govern small molecule-protein interactions more difficult.     

Short-term effects of angiotensin II receptor blockade in patients with primary glomerulonephritis: pilot study.

OBJECTIVE: There is evidence that angiotensin II, the main effector of renin-angiotensin system, plays a crucial role in the pathogenesis of chronic renal injury. Angiotensin II type 1 (AT-1) receptor blockers reduce renin-angiotensin system activity by blocking the receptor, the activation of which is responsible for the majority of deleterious angiotensin II effects. The aim of the present study was to investigate renal and metabolic effects of specific AT-1 receptor blocker-losartan in patients with primary glomerulonephritis. DESIGN: Pilot clinical study. SETTING: Department of Nephrology, Transplantology and Internal Medicine, Medical University of Gdańsk, Poland. PARTICIPANTS: Fifteen patients aged 43.3 +/- 11.3 years with primary glomerulonephritis confirmed by renal biopsy were studied. INTERVENTION: Creatinine clearance, urinary excretion of protein and uric acid, urinary activity of N-acetyl-beta-D-glucosaminidase, and serum concentrations of lipids, protein, and uric acid were evaluated before and after 3 months of losartan (Cozaar; Merck Sharp & Dohme, Harlow, Essex, United Kingdom) treatment at a dose of 25 mg daily. RESULTS: We found a significant reduction of urinary excretion of protein (P <.008; average, 32%). Results also revealed a decrease of serum uric acid level (P <.01), probably as a consequence of elevated uric acid urinary excretion (P <.09). No significant changes in creatinine clearance, N-acetyl-beta-D-glucosaminidase activity, protein, or lipid levels were observed. CONCLUSION: We concluded that losartan treatment at a small dose of 25 mg daily produces antiproteinuric effect without adverse effects, notably with no decrease of glomerular filtration, and simultaneously induces beneficial changes in purine metabolism.