Association between human polymorphic DNA markers and hypoxia adaptation in Sherpa detected by a preliminary genome scan.

Genetic determinants of resistance to hypobaric hypoxia in the Sherpa are still unknown. Since adaptive gene variants must still be subjected to positive selection, linkage disequilibrium between such variants and specific alleles of flanking DNA markers is expected. Following this line of reasoning, we performed a human genome scan using 998 polymorphic DNA markers in 7 unrelated Sherpa porters living in the Solu-Khumbu area. This minimalist approach succeeded in detecting 8 DNA markers showing homozygosity for the same shared allele. Analysis of additional DNA samples from 2 more Sherpa porters focused our attention on three polymorphic DNA markers (D6S1697, D14S274, D17S1795) showing homozygosity for the same shared allele in 8 out 9 tested individuals. Analysis of DNA samples from Sherpa and non-Sherpa populations of Nepal proved HW equilibrium in both populations for markers D14S274 and D17S1795, while an excess of heterozygotes was observed in the Sherpa population for marker D6S1697. A significant difference in allele frequencies for D14S274 and D17S1795 between the two populations was observed. These findings exclude the possibility that homozygosity for 3 specific loci in 8 unrelated individuals might be ascribed to inbreeding or recent genetic drift. We therefore conclude that the chromosomal segments detected by such DNA markers may include genes involved in adaptation to hypobaric hypoxia.

Modeling, analysis, and validation of a pneumatically driven left ventricle for use in mock circulatory systems.

In this work a pneumatically driven mock left ventricle and a native left ventricle are modeled and alternatively connected to the numerical model of a closed circulatory system comprising the systemic circulation, the left atrium, and inlet and outlet ventricular valves. By simulating physiological changes of the system working conditions, behavior and preload sensitivity of the pneumatic ventricle have been compared to those of a native ventricle. Results show that a pneumatic ventricle, when used as a fluid actuator in mock circulations, has low flexibility in reproducing different scenarios, its interaction with peripheral circulatory districts is characterized by non-physiological values, and its preload sensitivity is in poor agreement with physiological data. Results' analysis also shows that present mock circulatory systems for testing cardiovascular prostheses are inadequate, if a careful attention is not paid to the pumping action of the pneumatic ventricle. The presented computer model, validated by comparing numerical results with in vitro measurements available in the literature, can be used for designing in vitro experiments, while choosing the best control strategy for pneumatic systems.

Hybrid test bench for evaluation of any device related to mechanical cardiac assistance.

Hydraulic mock circulatory systems have low flexibility to allow tests of different cardiovascular devices and low precision when a reference model must be reproduced. In this paper a new bench is described. It combines the computer model of the environment in which the device will operate and the electro-hydraulic interfaces by which device and computer are connected. A models library provided with basic functions allows implementing many layouts of the bench, which in turn depend both on the device properties and the desired experiment. In case of an apical LVAD evaluation, the bench can reproduce right and left ventricles, pulmonary and systemic circulations, inlet and outlet LVAD cannulas. An interface forces the instantaneous calculated flow at the VAD input and feeds back the measured pressure to the computer; another interface works in a similar -but complementary- way at the VAD output. The paper focuses on the operating principle of the electro hydraulic interfaces which represent a relevant component of the bench, on the RT-Linux-based software architecture, on the models of the basic elements of the bench. A patent is under preparation. At the moment, only a portion of the bench has been developed. It consists of a piston-cylinder mechanism, which mimics the elastance-based mechanism of a natural ventricle, and a hydraulic circuit representing the arterial load according to a modified windkessel model and the venous return according to the Guyton's model. The pump is driven by a real-time simulation of the cardiovascular system. This preliminary layout allowed testing the piston-cylinder mechanism, its control, and the software. This electro-hydraulic interface has been used to reproduce a pulsatile pump working in different modes. The hybrid model approach can support the development of new cardiac assist devices from their computer model to their manufacture.

Long term effectiveness of intravenous immunoglobulin in Churg-Strauss syndrome.

OBJECTIVE: To study the long term effectiveness of intravenous immunoglobulin and plasmapheresis associated with prednisone and cyclophosphamide in Churg-Strauss syndrome. SUBJECTS: and methods: We studied 18 subjects with new onset Churg-Strauss syndrome. All received the "standard" treatment based on prednisone (1 mg/kg/day for 1 month and then slowly tapered) and cyclophosphamide (2 mg/kg/day for 6 months in severe cases). In nine patients, synchronised cycles with plasmapheresis and intravenous immunoglobulin (2 g/kg) were repeated monthly for 6 months and every other month for a further three cycles. Clinical (disease activity monitored by Birmingham vasculitis activity score (BVAS) and damage index (modified Rankin score)) and functional (C reactive protein, blood eosinophil count, and electromyogram-electoneurogram) parameters were collected during treatment and the 3 year follow up period. RESULTS: After 12 months, all patients in the treatment group and four (44%) in the control group were in remission. At the end of the 3 year follow up period, we documented significant differences in BVAS (p<0.01), global damage (p<0.02), modified Rankin score (p<0.04), and the daily maintenance prednisone dose (p<0.002) between the two groups. We found a tendency towards lower frequency of relapse and incidence of osteoporosis in the treatment group. CONCLUSION: Complete clinical and functional recovery with a long term stable remission and a low incidence of side effects can be achieved by intravenous immunoglobulin associated with plasmapheresis in patients with Churg-Strauss syndrome.

Disease genes and intracellular protein networks.

By a computational approach we reconstructed genomic transcriptional profiles of 19 different adult human tissues, based on information on activity of 27,924 genes obtained from unbiased UniGene cDNA libraries. In each considered tissue, a small number of genes resulted highly expressed or "tissue specific." Distribution of gene expression levels in a tissue appears to follow a power law, thus suggesting a correspondence between transcriptional profile and "scale-free" topology of protein networks. The expression of 737 genes involved in Mendelian diseases was analyzed, compared with a large reference set of known human genes. Disease genes resulted significantly more expressed than expected. The possible correspondence of their products to important nodes of intracellular protein network is suggested. Auto-organization of the protein network, its stability in time in the differentiated state, and relationships with the degree of genetic variability at genome level are discussed.

Are behaviour and motor performances of rheumatoid arthritis patients influenced by subclinical cognitive impairments? A clinical and neuroimaging study.

OBJECTIVE: To determine whether some behavioural manifestations and poor motor performances in patients affected by rheumatoid arthritis (RA) are due to subclinical cognitive defects. METHODS: We performed a psychometric assessment of 30 patients affected by RA exploring several cognitive domains such as memory, visual-spatial integration, motor planning, mental flexibility, relating performances with morphological and functional neuroimaging (MRI and SPECT). We also related the cognitive data with the Ritchie and Lee indexes and other clinical parameters. RESULTS: We found an impairment in visual-spatial tasks in 71% of patients with a high correlation to activity and disease severity as expressed by the Ritchie and Lee indexes (p < 0.005; p < 0.01). Furthermore, we detected in 38% of patients some difficulties in mental flexibility related to the Lee Index (p < 0.05). These poor performances are related to hypoperfusion of the frontal and parietal lobes as detected by brain SPECT; this finding is more evident in patients with brain white matter alterations on MRI. CONCLUSIONS: Our data allow us to hypothesize that manual dexterity could be due to a disconnection between subcortical white matter and parietal-frontal lobes because of microangiopathy; furthermore, a chronic reduction in sensorial stimuli by impaired joints could lead to produce an alteration in motor planning cognitive processes.

Cyclosporin A and intravenous immunoglobulin treatment in polymyositis/dermatomyositis.

OBJECTIVE: To describe the treatment of polymyositis (PM) and dermatomyositis (DM) with prednisone (PRED) and cyclosporin A (CSA) alone or associated with intravenous immunoglobulin (IVIg) and plasmapheresis (PEX). METHODS: Between 1992 and 1999 CSA and PRED were used to treat 20 patients with idiopathic myositis (12 with DM, eight with PM), diagnosed according to the Bohan and Peter criteria. In patients with refractory or relapsed disease, IVIg was added alone (seven cases) or synchronised with PEX (six cases). A standardised protocol was used to evaluate the patients, and assess disease activity and treatment response. RESULTS: Despite a transient response to PRED and CSA in 16/20 cases, this combination did not induce full remission in 13/20 cases, which led to the IVIg trial with or without PEX. Patients receiving PRED and CSA plus IVIg had a significantly higher probability of maintaining complete remission at the end of the four year follow up period than those treated with PRED and CSA alone (p<0.001). No further benefit was added by the PEX. The presence of arthritis significantly correlated with a poorer response to treatment (p<0.05). Adverse effects were gingival hyperplasia (one patient) and transient renal dysfunction (one). CONCLUSIONS: This open study suggests that combined treatment with PRED, CSA, and IVIg is useful in patients with myositis, even those with refractory or relapsed disease; no increase in the number or type of side effects is seen.

Italian population data for D1S1656, D3S1358, D8S1132, D10S2325, VWA, FES/FPS, and F13A01.

Allele frequencies for seven STRs loci were obtained from a sample of 215 unrelated healthy Italian individuals.

Differential expression of genes coding for ribosomal proteins in different human tissues.

MOTIVATION: To perform a computational and statistical study on a large set of gene expression data pertaining six adult human tissues (brain, liver, skeletal muscle, ovary, retina and uterus) for analyzing the expression of ribosomal protein genes. RESULTS: Unexpectedly, in each of the considered tissues large variations in the expression of ribosomal protein genes were observed. Moreover, when comparing the expression levels of 89 ribosomal protein genes in six different tissues, 13 genes appeared differentially expressed among tissues. AVAILABILITY: The expression data of the ribosomal protein genes together with supplementary material (complete transcriptional profiles of the considered human tissues) are freely available at the site GETProfiles (http://telethon.bio.unipd.it/GETProfiles/). CONTACT: danieli@bio.unipd.it

Coagulative modifications in patients with systemic sclerosis treated with iloprost or nifedipine.

This study compared iloprost and nifedipine to ascertain whether they could improve parameters of endothelial and platelet functions in the treatment of Raynaud's phenomenon secondary to systemic sclerosis. Thirteen patients affected by systemic sclerosis were treated with intravenous infusion of iloprost, and 7 patients were treated with oral nifedipine. Blood samples were taken at baseline and after 6 and 12 months of therapy to assess main serological indexes of endothelial damage, thrombin activation, fibrinolysis, as well as natural inhibitors of coagulation. After 12 months of therapy, the patients treated with iloprost had a significant decrease in thrombomodulin levels (p = 0.02) and a significant increase in tissue-plasminogen activator levels (p = 0.007), in comparison with the patients taking nifedipine (p = 0.007). Moreover, patients treated with nifedipine showed increased levels of thrombin-antithrombin complex after 12 months of therapy in comparison with baseline values (p = 0.03) and in comparison with the values of the patients treated with iloprost over the same period (p = 0.05). These preliminary results thus seem to indicate that iloprost plays an important, if at least partial, role in the protection and restoration of endothelial integrity in patients with systemic sclerosis.

Detecting differentially expressed genes in multiple tag sampling experiments: comparative evaluation of statistical tests.

The comparison of several statistical methods currently used for detection of differentially expressed genes was attempted both by a simulation approach and by the analysis of data sets of human expressed sequence tags, obtained from UniGene. In the simulated mixed case, mimicking a situation close to reality, the general chi(2) test was unexpectedly the most efficient in multiple tag sampling experiments, especially when dealing with variations affecting weakly expressed genes. On the other hand, Audic and Claverie's method proved the most efficient for detecting differences in gene expression when dealing with pairwise comparisons. By applying the above methods on UniGene-based data sets concerning two human kidney tumours compared with normal kidney tissue, three novel genes overexpressed in these tumours were identified. Software and additional information on statistical methodologies, simulation approach and data are available at http://telethon.bio.unipd.it/bioinfo/IDEG6/.

Identification of mutations in the cardiac ryanodine receptor gene in families affected with arrhythmogenic right ventricular cardiomyopathy type 2 (ARVD2).

Arrhythmogenic right ventricular dysplasia type 2 (ARVD2, OMIM 600996) is an autosomal dominant cardiomyopathy, characterized by partial degeneration of the myocardium of the right ventricle, electrical instability and sudden death. The disease locus was mapped to chromosome 1q42--q43. We report here on the physical mapping of the critical ARVD2 region, exclusion of two candidate genes (actinin 2 and nidogen), elucidation of the genomic structure of the cardiac ryanodine receptor gene (RYR2) and identification of RYR2 mutations in four independent families. In myocardial cells, the RyR2 protein, activated by Ca(2+), induces the release of calcium from the sarcoplasmic reticulum into the cytosol. RyR2 is the cardiac counterpart of RyR1, the skeletal muscle ryanodine receptor, involved in malignant hyperthermia (MH) susceptibility and in central core disease (CCD). The RyR2 mutations detected in the present study occurred in two highly conserved regions, strictly corresponding to those where mutations causing MH or CCD are clustered in the RYR1 gene. The detection of RyR2 mutations causing ARVD2, reported in this paper, opens the way to pre-symptomatic detection of carriers of the disease in childhood, thus enabling early monitoring and treatment.

Mutations in the cardiac ryanodine receptor gene (hRyR2) underlie catecholaminergic polymorphic ventricular tachycardia.

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia is a genetic arrhythmogenic disorder characterized by stress-induced, bidirectional ventricular tachycardia that may degenerate into cardiac arrest and cause sudden death. The electrocardiographic pattern of this ventricular tachycardia closely resembles the arrhythmias associated with calcium overload and the delayed afterdepolarizations observed during digitalis toxicity. We speculated that a genetically determined abnormality of intracellular calcium handling might be the substrate of the disease; therefore, we considered the human cardiac ryanodine receptor gene (hRyR2) a likely candidate for this genetically transmitted arrhythmic disorder. METHODS AND RESULTS: Twelve patients presenting with typical catecholaminergic polymorphic ventricular tachycardia in the absence of structural heart abnormalities were identified. DNA was extracted from peripheral blood lymphocytes, and single-strand conformation polymorphism analysis was performed on polymerase chain reaction-amplified exons of the hRyR2 gene. Four single nucleotide substitutions leading to missense mutations were identified in 4 probands affected by the disease. Genetic analysis of the asymptomatic parents revealed that 3 probands carried de novo mutations. In 1 case, the identical twin of the proband died suddenly after having suffered syncopal episodes. The fourth mutation was identified in the proband, in 4 clinically affected family members, and in none of 3 nonaffected family members in a kindred with 2 sudden deaths that occurred at 16 and 14 years, respectively, in the sisters of the proband. CONCLUSIONS: We demonstrated that, in agreement with our hypothesis, hRyR2 is a gene responsible for catecholaminergic polymorphic ventricular tachycardia.