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Biomedical subjects

M Zoli

Publications and source records attributed to M Zoli.

At least 19 recordsLinked to original sources

Metformin in non-alcoholic steatohepatitis.

There is no established treatment for steatohepatitis in patients who are not alcoholics. This disease is a potentially progressive liver disease associated with hepatic insulin resistance. Only a weight-reducing diet in overweight patients has proved effective. We treated 20 patients who had steatohepatitis but were not alcoholics with metformin (500 mg three times a day for 4 months), an agent that improves hepatic insulin sensitivity. When compared with the six individuals not complying with treatment, long-term metformin significantly reduced mean transaminase concentrations, which returned to normal in 50% of actively-treated patients. Also, insulin sensitivity improved significantly and liver volume decreased by 20%. Similar data have been reported in insulin-resistant ob/ob mice with fatty liver. A randomised-controlled study is needed.

Adult↗

Adenosine A2A agonist CGS 21680 decreases the affinity of dopamine D2 receptors for dopamine in human striatum.

Adenosine A2A receptors (A2AR) and dopamine D2 receptors (D2R) are highly concentrated in the striatum, where they are co-localized and exert reciprocal antagonistic interactions. It has been suggested that the A2R/D2R interactions might provide a therapeutic approach for basal ganglia disorders, such as Parkinson's disease, and schizophrenia. In the present work evidence is presented for the existence of an A2AR/D2R interaction in human brain by using quantitative autoradi- ography. The areas analyzed were the dorsal caudate nucleus and putamen. Parallel studies were performed in rat striatal sections. The A2AR agonist CGS 21680 was found to significantly increase IC50 values of competitive inhibition curves of the D2R/D3R antagonist [125I]iodosulpiride vs dopamine both in rat striatal and human striatal brain sections.

Adenosine↗

Molecular and physiological diversity of nicotinic acetylcholine receptors in the midbrain dopaminergic nuclei.

Nicotinic acetylcholine receptors (nAChRs) on dopaminergic (DA) and GABAergic (Gaba) projection neurons of the substantia nigra (SN) and ventral tegmental area (VTA) are characterized by single-cell RT-PCR and patch-clamp recordings in slices of rat and wild-type, beta2-/-, alpha4-/-, and alpha7-/- mice. The eight nAChR subunits expressed in these nuclei, alpha3-7 and beta2-4, contribute to four different types of nAChR-mediated currents. Most DA neurons in the SN and VTA express two nAChR subtypes. One is inhibited by dihydro-beta-erythroidine (2 microm), alpha-conotoxin MII (10 nm), and methyllycaconitine (1 nm) but does not contain the alpha7 subunit; it possesses a putative alpha4alpha6alpha5(beta2)(2) composition. The other subtype is inhibited by dihydro-beta-erythroidine (2 microm) and has a putative alpha4alpha5(beta2)(2) composition. Gaba neurons in the VTA exhibit a third subtype with a putative (alpha4)(2)(beta2)(3) composition, whereas Gaba neurons in the SN have either the putative (alpha4)(2)(beta2)(3) oligomer or the putative alpha4alpha6alpha5(beta2)(2) oligomer. The fourth subtype, a putative (alpha7)(5) homomer, is encountered in less than half of DA and Gaba neurons, in the SN as well as in the VTA. Neurons in the DA nuclei thus exhibit a diversity of nAChRs that might differentially modulate reinforcement and motor behavior.

Animals↗

Functional striatal hypodopaminergic activity in mice lacking adenosine A(2A) receptors.

Adenosine and caffeine modulate locomotor activity and striatal gene expression, partially through the activation and blockade of striatal A(2A) receptors, respectively. The elucidation of the roles of these receptors benefits from the construction of A(2A) receptor-deficient mice (A(2A)-R(-/-)). These mice presented alterations in locomotor behaviour and striatal expression of genes studied so far, which are unexpected regarding the specific expression of A(2A) receptor by striatopallidal neurones. To clarify the functions of A(2A) receptors in the striatum and to identify the mechanisms leading to these unexpected modifications, we studied the basal expression of immediate early and constitutive genes as well as dopamine and glutamate neurotransmission in the striatum. Basal zif268 and arc mRNAs expression was reduced in mutant mice by 60-80%, not only in the striatum but also widespread in the cerebral cortex and hippocampus. Striatal expression of substance P and enkephalin mRNAs was reduced by about 50% and 30%, respectively, whereas the expression of GAD67 and GAD65 mRNAs was slightly increased and unaltered, respectively. In vivo microdialysis in the striatum revealed a 45% decrease in the extracellular dopamine concentration and three-fold increase in extracellular glutamate concentration. This was associated with an up-regulation of D(1) and D(2) dopamine receptors expression but not with changes in ionotropic glutamate receptors. The levels of tyrosine hydroxylase and of striatal and cortical glial glutamate transporters as well as adenosine A(1) receptors expression were indistinguishable between A(2A)-R(-/-) and wild-type mice. Altogether these results pointed out that the lack of A(2A) receptors leads to a functional hypodopaminergic state and demonstrated that A(2A) receptors are necessary to maintain a basal level in immediate early and constitutive genes expression in the striatum and cerebral cortex, possibly via their control of dopamine pathways.

ATP-Binding Cassette Transporters↗

Impact of interferon therapy on the natural history of hepatitis C virus related cirrhosis.

BACKGROUND: The role of interferon treatment on the natural history of hepatitis C virus related cirrhosis is under debate. AIM: To evaluate the effect of interferon on the clinical course of compensated hepatitis C virus related cirrhosis. PATIENTS AND METHODS: Seventy two cirrhotic patients treated with interferon and 72 untreated controls matched treated patients with for quinquennia of age, sex, and Child-Pugh's score were enrolled in a prospective non-randomised controlled trial. Treated patients received leucocytic interferon alfa, with an escalating schedule for 12 months. The incidence and risk (Cox regression analysis) of clinical complications (hepatocellular carcinoma, ascites, jaundice, variceal bleeding, and encephalopathy) and death were calculated. RESULTS: Over median follow up periods of 55 months for treated and 58 for untreated subjects, seven and nine patients, respectively, died, and 20 and 32, respectively, developed at least one clinical complication (ns). Hepatocellular carcinoma developed in six treated and 19 untreated patients (p=0.018). Seven treated patients showed sustained aminotranferase normalisation and none died or developed complications. Clinical complications were significantly associated with low albumin, bilirubin, and prothrombin activity while hepatocellular carcinoma was significantly related to no treatment with interferon, oesophageal varices, and high alpha fetoprotein levels. By stratified analysis, the beneficial effect of interferon was statistically evident only in patients with baseline alpha fetoprotein levels > or =20 ng/ml. CONCLUSIONS: Interferon does not seem to affect overall or event free survival of patients with hepatitis C virus related cirrhosis while it seems to prevent the development of hepatocellular carcinoma. Patients who achieved sustained aminotransferase normalisation survived and did not develop any complications during follow up.

Antiviral Agents↗

Coeliac disease in patients with autoimmune thyroiditis.

BACKGROUND AND AIMS: The close association between coeliac disease and autoimmunity prompted us to perform an antibody screening for gluten-sensitive enteropathy in patients with autoimmune thyroid dysfunction. METHODS: Sera from 220 patients with autoimmune thyroiditis, 50 euthyroid subjects with thyroid nodules and 250 blood donors were tested for IgA anti-tissue transglutaminase (anti-tTG) and antiendomysial antibodies (EmA). RESULTS: IgA anti-tTG was positive in 7 patients with autoimmune thyroiditis, whereas IgA EmA was found only in 6 of them. Duodenal biopsy confirmed coeliac disease diagnosis disclosing marked and mild villous atrophy in 6 and 1 of them, respectively. All but 2 of the 7 coeliacs did not show any sign of malabsorption. All euthyroid controls were negative for IgA antibodies, whereas 1 blood donor, positive for both IgA anti-tTG and EmA, was found to be coeliac. The prevalence of coeliac disease in patients with autoimmune thyroiditis (3.2%) was significantly higher than that found in blood donors (0.4%) (p = 0.022, Fisher's exact test). CONCLUSIONS: Antibody screening for coeliac disease should be included in the work-up of patients with autoimmune thyroiditis. Either IgA anti-tTG or EmA may be used, even though the former seems to be slightly more sensitive than the latter.

Adolescent↗

Dopamine D1 and adenosine A1 receptors form functionally interacting heteromeric complexes.

The possible molecular basis for the previously described antagonistic interactions between adenosine A(1) receptors (A(1)R) and dopamine D(1) receptors (D(1)R) in the brain have been studied in mouse fibroblast Ltk(-) cells cotransfected with human A(1)R and D(1)R cDNAs or with human A(1)R and dopamine D(2) receptor (long-form) (D(2)R) cDNAs and in cortical neurons in culture. A(1)R and D(1)R, but not A(1)R and D(2)R, were found to coimmunoprecipitate in cotransfected fibroblasts. This selective A(1)R/D(1)R heteromerization disappeared after pretreatment with the D(1)R agonist, but not after combined pretreatment with D(1)R and A(1)R agonists. A high degree of A(1)R and D(1)R colocalization, demonstrated in double immunofluorescence experiments with confocal laser microscopy, was found in both cotransfected fibroblast cells and cortical neurons in culture. On the other hand, a low degree of A(1)R and D(2)R colocalization was observed in cotransfected fibroblasts. Pretreatment with the A(1)R agonist caused coclustering (coaggregation) of A(1)R and D(1)R, which was blocked by combined pretreatment with the D(1)R and A(1)R agonists in both fibroblast cells and in cortical neurons in culture. Combined pretreatment with D(1)R and A(1)R agonists, but not with either one alone, substantially reduced the D(1)R agonist-induced accumulation of cAMP. The A(1)R/D(1)R heteromerization may be one molecular basis for the demonstrated antagonistic modulation of A(1)R of D(1)R receptor signaling in the brain. The persistence of A(1)R/D(1)R heteromerization seems to be essential for the blockade of A(1)R agonist-induced A(1)R/D(1)R coclustering and for the desensitization of the D(1)R agonist-induced cAMP accumulation seen on combined pretreatment with D(1)R and A(1)R agonists, which indicates a potential role of A(1)R/D(1)R heteromers also in desensitization mechanisms and receptor trafficking.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

Evidence for adenosine/dopamine receptor interactions: indications for heteromerization.

Evidence has been obtained for adenosine/dopamine interactions in the central nervous system. There exists an anatomical basis for the existence of functional interactions between adenosine A(1)R and dopamine D(1)R and between adenosine A(2A) and dopamine D(2) receptors in the same neurons. Selective A(1)R agonists affect negatively the high affinity binding of D(1) receptors. Activation of A(2A) receptors leads to a decrease in receptor affinity for dopamine agonists acting on D(2) receptors, specially of the high-affinity state. These interactions have been reproduced in cell lines and found to be of functional significance. Adenosine/dopamine interactions at the behavioral level probably reflect those found at the level of dopamine receptor binding and transduction. All these findings suggest receptor subtype-specific interactions between adenosine and dopamine receptors that may be achieved by molecular interactions (e.g., receptor heterodimerization). At the molecular level adenosine receptors can serve as a model for homomeric and heteromeric protein-protein interactions. A1R forms homodimers in membranes and also form high-order molecular structures containing also heterotrimeric G-proteins and adenosine deaminase. The occurrence of clustering also clearly suggests that G-protein- coupled receptors form high-order molecular structures, in which multimers of the receptors and probably other interacting proteins form functional complexes. In view of the occurrence of homodimers of adenosine and of dopamine receptors it is speculated that heterodimers between these receptors belonging to two different families of G-protein-coupled receptors can be formed. Evidence that A1/D1 can form heterodimers in cotransfected cells and in primary cultures of neurons has in fact been obtained. In the central nervous system direct and indirect receptor-receptor interactions via adaptor proteins participate in neurotransmission and neuromodulation and, for example, in the establishment of high neural functions such as learning and memory.

Animals↗

Localization of nAChR subunit mRNAs in the brain of Macaca mulatta.

We present here a systematic mapping of nAChR subunit mRNAs in Macaca mulatta brain. A fragment, from the transmembrane segments MIII to MIV of Macaca neuronal nAChR subunits was cloned, and shown to exhibit high identity (around 95%) to the corresponding human subunits. Then, specific oligodeoxynucleotides were synthesized for in situ hybridization experiments. Both alpha4 and beta2 mRNA signals were widely distributed in the brain, being stronger in the thalamus and in the dopaminergic cells of the mesencephalon. Most brain nuclei displayed both alpha4 and beta2 signals with the exception of some basal ganglia regions and the reticular thalamic nucleus which were devoid of alpha4 signal. alpha6 and beta3 mRNA signals were selectively concentrated in the substantia nigra and the medial habenula. The strongest signals for alpha3 or beta4 mRNAs were found in the epithalamus (medial habenula and pineal gland), whereas there were no specific alpha3 or beta4 signals in mesencephalic dopaminergic nuclei. alpha5 and alpha7 mRNA signals were found in several brain areas, including cerebral cortex, thalamus and substantia nigra, although at a lower level than alpha4 and beta2. The distribution of alpha3, alpha4, alpha5, alpha6, alpha7, beta2, beta3 and beta4 subunit mRNAs in the monkey is substantially similar to that observed in rodent brain. Surprisingly, alpha2 mRNA signal was largely distributed in the Macaca brain, at levels comparable with those of alpha4 and beta2. This observation represents the main difference between rodent and Macaca subunit mRNA distribution and suggests that, besides alpha4beta2*, alpha2beta2* nAChRs constitute a main nAChR isoform in primate brain.

Animals↗

Protective effects of delapril combined with indapamide or hydrochlorothiazide in spontaneously hypertensive stroke-prone rats: a comparative dose-response analysis.

In previous articles, we have shown that the combination of the angiotensin-converting enzyme (ACE) inhibitor delapril (12 mg/kg/day) and the diuretic indapamide (1 mg/kg/ day) was able to prolong the life span significantly in salt-loaded stroke-prone spontaneously hypertensive rats (SHRsp). Because this finding was partly dependent on the antagonism of salt-loading effects by pharmacologic induction of diuresis, which prevented any increase in blood pressure values, we decided to evaluate whether lower doses of the combination could be equally protective without changing the progression of hypertension. Thus, we studied several treatments with progressively lower doses of delapril (6, 3, or 1.5 mg/kg/day) combined with indapamide (0.5, 0.25, or 0.125 mg/kg/day) or hydrochlorothiazide (2.5, 1.25, or 0.625 mg/kg/day) in salt-loaded SHRsp. Salt-loaded untreated animals were considered to be the control group. In agreement with previous experiments, control rats reached 50% mortality approximately 7 weeks after the beginning of salt loading. The combination of delapril and hydrochlorothiazide at the two lowest doses was not able to delay animal death significantly, whereas treatment with delapril and indapamide at the lowest dose was effective (50% survival rate, 15 weeks). The groups treated with the highest dose of delapril and hydrochlorothiazide or with the intermediate or highest dose of delapril and indapamide did not reach 50% mortality by the end of the experiment, at 44 weeks of treatment (i.e., when animals reached age 1 year). Only the highest delapril and indapamide doses were able to increase diuresis, but for a relatively short period. None of the treatments was able to lower or control blood pressure levels adequately. Therefore, blood pressure levels by themselves were not predictive of rat mortality. In contrast, the maximal value of proteinuria in the weeks preceding death was inversely correlated with the survival time. In conclusion, this study shows that low doses of an ACE inhibitor in combination with a diuretic can be effectively protective in a model of severe hypertension, independent of any change in blood pressure levels.

Angiotensin-Converting Enzyme Inhibitors↗

Natural history of cirrhotic patients with small esophageal varices: a prospective study.

OBJECTIVE: Contrasting data are available on the natural history and bleeding risk of small esophageal varices. The aim of this prospective study was to evaluate a large series of consecutive cirrhotics with a first endoscopic diagnosis of small varices. METHODS: Between 1987 and 1992, 258 patients with small varices and no previous bleeding were enrolled. Patients were clinically examined every 6 months and were followed until a first episode of bleeding and/or death, or until June 1998. None received any treatment to prevent bleeding. Endoscopies were planned at 18-month intervals. RESULTS: The cumulative risk of bleeding was low (3% at 2 yr and 8% at 4 yr) and remained low in patients in whom varices remained small at 2nd endoscopy, whereas it increased significantly when varices enlarged. The increase of varices appeared to be rather linear in time: at the 2nd endoscopy varices remained small in 79% of patients and increased in 21%; at the 3rd endoscopy varices remained small in 55%, whereas at the 4th 33% of patients still had small varices. Clinical and biochemical data at the 1st and 2nd endoscopy were included in a multiple logistic regression analysis. Only the increase in Child-Pugh score appeared to be a significant predictor of enlarged varices; the risk of aggravation increased by 37.5% for every unit of impairment of the score. CONCLUSIONS: The present study shows that patients with small varices have a low bleeding risk. An increase in Child-Pugh score during follow-up suggests enlargement of varices, thus an increase in bleeding risk. In these patients closer endoscopic surveillance is recommended.

Chi-Square Distribution↗

Prognostic indicators of risk for first variceal bleeding in cirrhosis: a multicenter study in 711 patients to validate and improve the North Italian Endoscopic Club (NIEC) index.

OBJECTIVE: The best known indicator of risk for first bleeding in patients with cirrhosis without previous bleeding is the index devised by the North Italian Endoscopic Club for the Study and Treatment of Esophageal Varices (NIEC index), which results from the combination of size of esophageal varices, severity of red wale marks, and Child-Pugh class. Its efficiency is far from optimal, and validation studies have reported sensitivities and specificities markedly lower than those reported in the original study. In the present study we analyzed the efficiency of NIEC index in a large series of cirrhotic patients with varices without previous bleeding. In addition, we tried to improve the effectiveness of the index by modifying it, and to validate the modifications in an independent group of patients. METHODS: A total of 627 patients were enrolled and followed until either a variceal bleeding or for a maximum of 2 yr. During this time, 117 experienced a first variceal RESULTS: Using Cox's regression analysis, size of varices, severity of red wale marks, and Child-Pugh score were significant and independent predictors of first bleeding, as already noted in the original report of the NIEC group. However, coefficients and standard errors were markedly different, and the importance of size of esophageal varices in the regression was much larger, whereas that of Child-Pugh score was much lower. According to these data, a revised index was developed (Rev-NIEC). Using receiver operating characteristic (ROC) curve analysis, the revised index showed a larger efficiency, and the area under the curve was significantly larger (0.80 +/- 0.02 vs 0.74 +/- 0.02; p < 0.01). In particular, the curve showed that for a specificity of 75%, the new index had a sensitivity of 72% compared to that of 55% of the NIEC index. Validation in an independent sample of 84 patients showed good agreement between predicted and observed risk for bleeding. Validation with the bootstrap technique also showed adequate stability of the results. CONCLUSIONS: The revised index seems to be superior to the traditional index, and may turn out to be more useful in the selection of patients for different therapeutic procedures and in the stratification of patients in clinical trials.

Aged↗

Changes in nicotinic acetylcholine receptor subunit mRNAs and nicotinic binding in spontaneously hypertensive stroke prone rats.

We have studied nicotinic acetylcholine receptors in spontaneously hypertensive 'stroke prone' (SHsp) rats. We found a significant decrease in 125I-alpha-bungarotoxin binding and alpha7 subunit mRNA levels in cortical areas of the SHsp rats with respect to Wistar Kyoto (WKy) normotensive rats. Antihypertensive drug treatment counteracted these changes in cerebral cortex but not in hippocampus. No significant change was instead found in [3H]-epibatidine binding and alpha4 and beta2 subunit mRNA levels. SHsp rats showed decreased latency at the active avoidance test and transiently increased threshold at both hot-plate and tail-flick tests in comparison with WKy rats. None of these behavioral parameters was correlated with 125I-alpha-bungarotoxin binding in cortical areas. In conclusion, present data show a preferential impairment of alpha-bungarotoxin sensitive nAChRs in SHsp rats.

Animals↗

Involvement of alpha6 nicotinic receptor subunit in nicotine-elicited locomotion, demonstrated by in vivo antisense oligonucleotide infusion.

Enhanced locomotion in a habituated environment is a well documented effect of nicotine mediated by the mesotelencephalic dopaminergic system. The nicotinic receptor subunit alpha6 is, among other subunits, strongly expressed in the dopaminergic neurons of the mesencephalon. To examine the functional role of this subunit, we inhibited its expression in vivo using antisense oligonucleotides. In vitro treatments of embryonic mesencephalic neuron cultures demonstrated that the alpha6 antisense oligonucleotides caused a marked decrease in the level of alpha6 subunit protein. In vivo, 1 week infusion of alpha6 antisense oligonucleotides by osmotic mini-pump reduced the effect of nicotine on locomotor activity in habituated environment by 70%. These data support the notion that the effects of nicotine on the dopaminergic system involve alpha6 subunit containing nAChRs.

Amino Acid Sequence↗

Increased neurodegeneration during ageing in mice lacking high-affinity nicotine receptors.

We have examined neuroanatomical, biochemical and endocrine parameters and spatial learning in mice lacking the beta2 subunit of the nicotinic acetylcholine receptor (nAChR) during ageing. Aged beta2(-/-) mutant mice showed region-specific alterations in cortical regions, including neocortical hypotrophy, loss of hippocampal pyramidal neurons, astro- and microgliosis and elevation of serum corticosterone levels. Whereas adult mutant and control animals performed well in the Morris maze, 22- to 24-month-old beta2(-/-) mice were significantly impaired in spatial learning. These data show that beta2 subunit-containing nAChRs can contribute to both neuronal survival and maintenance of cognitive performance during ageing. beta2(-/-) mice may thus serve as one possible animal model for some of the cognitive deficits and degenerative processes which take place during physiological ageing and in Alzheimer's disease, particularly those associated with dysfunction of the cholinergic system.

Aging↗

Volume transmission in the CNS and its relevance for neuropsychopharmacology.

The terms 'wiring' and 'volume' transmission (WT and VT) have been introduced to provide a systematic categorization of intercellular communication in the brain. WT is one-to-one transmission and includes classical synapses, gap junctions and membrane juxtapositions, whereas VT is a one-to-many transmission and includes paracrine and endocrine-like transmissions in the brain extracellular space and cerebrospinal fluids. Any brain cell can participate in WT and VT and any kind of substance (e.g. ions, classical transmitters, peptides, neurosteroids) can be a signal in WT and VT. These concepts are relevant for the pharmacokinetics and actions of neuropsychoactive drugs. These drugs can be regarded as exogenous VT signals in that they diffuse in the cerebral extracellular space and are constrained there by the same factors that influence migration of endogenous VT signals. In addition, neuropsychoactive drugs can better mimic and more effectively interact with the relatively unconstrained VT-type transmissions than with the rigidly constrained WT mechanisms, such as synaptic transmission.

Animals↗

On the distribution patterns of D1, D2, tyrosine hydroxylase and dopamine transporter immunoreactivities in the ventral striatum of the rat.

The distribution of dopamine D1 and D2 receptor immunoreactivities in the nucleus accumbens and the olfactory tubercle of adult and postnatal male rats were compared with the distribution of tyrosine hydroxylase and dopamine transporter immunoreactivities. An overall co-distribution of D1 and D2 receptor immunoreactivities with tyrosine hydroxylase immunoreactivity was found in the nucleus accumbens and the olfactory tubercle. However, the major finding in this study was, following a more detailed analysis in coronal sections of the shell part of the nucleus accumbens, the existence of nerve cell patches of strong D1 receptor immunoreactivity associated with low D2 receptor, dopamine transporter and tyrosine hydroxylase immunoreactivities. These patches were mainly surrounded by areas of strong D2 receptor, tyrosine hydroxylase and dopamine transporter immunoreactivities and could be found also in the olfactory tubercle. Similar observations were made in postnatal rats. Serial reconstructions of the patches of strong D1 receptor immunoreactivity in the rostrocaudal direction were made. The patches formed a continuous tubular nerve cell system in the shell part of the nucleus accumbens. Since this nerve cell system was found to be surrounded by a high density of dopamine terminals, it may represent a compartment where dopamine transmission mainly acts on D1 receptors via local diffusion (i.e. via volume transmission). However, it must be noted that the D1 receptor rich patches constitute only a small fraction of the nucleus accumbens and the overall density of tyrosine hydroxylase immunoreactive terminals correlates with the density of both D1 and D2 receptors in the nucleus accumbens. In conclusion, the present paper gives new aspects on the chemical microarchitecture of the nucleus accumbens.

Aging↗