Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Behaviour of S-metolachlor and its oxanilic and ethanesulfonic acids metabolites under fresh vs. partially decomposed cover crop mulches: A laboratory study

At the time of spring pre-emergent herbicide application, the soil surface in conservation agriculture is most of the time covered by cover crops (CC) mulches. The state of these mulches depends on their destruction date and on the selected species. Sorption and degradation of ¹⁴C-S-metolachlor on and within 8 decaying CC-covered (2 species × 4 initial decomposition state) soils corresponding to conservation agriculture were compared to its fate in bare soil (BS) corresponding to conventional agriculture. ¹⁴C-S-metolachlor and its metabolites distribution between mineralized, extractable and non-extractable (NER) fractions was determined at 5 dates during a 20 °C/84-d period. Herbicide mineralization was weak (<2%) for both CC and BS. Extractability of ¹⁴C in BS was intermediate between CC that were decomposed 28 or 56 days and 0 or 6 days before application. Degradates consisted in up to 43% of total radioactivity, with specificities according to the CC or soil compartment. NER formation was equivalent in BS and in the much decomposed CC-amended microcosms, and was stronger in less decomposed CC. S-metolachlor DT₅₀ was 23-d in BS, and 9, 15, 39 and 25-d for CC ordered by increased decomposition state at the time of application. These results were attributed to the proportion of ¹⁴C intercepted by CC, and to higher levels of organic matter and microbial activity in less decomposed CC as compared with more decomposed ones. Then the state of decomposition level of CC residues determines the behaviour of SMOC (S-metolachlor) sprayed on the mulch in the conditions of conservation agriculture.

Observed volatilization fluxes of S-metolachlor and benoxacor applied on soil with and without crop residues

Volatilization may represent a major dissipation pathway for pesticides applied to soils or crops, and these losses may be modified by soil surface conditions or in the presence of plant residues. This paper investigates the effect of surface conditions on volatilization through experimental results. The two experiments consisted of volatilization flux measurements for 3 days after an application of S-metolachlor together with benoxacor: one with two wind tunnels to compare the effect of the presence of crop residues on the soil on volatilization losses and another one at the field scale from bare soil without crop residues. Volatilization fluxes were large immediately after application (between 77 and 223 ng m^-2 s^-1 for S-metolachlor depending on experimental conditions), decreasing down to a few nanograms per square meter per second on the last day. Volatilization fluxes followed a diurnal cycle driven by environmental conditions. The losses found for both compounds were in accordance with their physicochemical properties. The crop residue on the soil surface modified soil surface conditions-primarily the soil water content essentially, the degradation of S-metolachlor, and the dynamics of volatilization loss.

Fate of glyphosate and degradates in cover crop residues and underlying soil: A laboratory study

The increasing use of cover crops (CC) may lead to an increase in glyphosate application for their destruction. Sorption and degradation of (14)C-glyphosate on and within 4 decaying CC-amended soils were compared to its fate in a bare soil. (14)C-Glyphosate and its metabolites distribution between mineralized, water-soluble, NH4OH-soluble and non-extractable fractions was determined at 5 dates during a 20 °C/84-d period. The presence of CC extends (14)C-glyphosate degradation half-life from 7 to 28 days depending on the CC. (14)C-Glyphosate dissipation occurred mainly through mineralization in soils and through mineralization and bound residue formation in decaying CC. Differences in sorption and degradation levels were attributed to differences in composition and availability to microorganisms. CC- and soil-specific dissipation patterns were established with the help of explicit relationships between extractability and microbial activity.

Nature and decomposition degree of cover crops influence pesticide sorption: quantification and modelling

This study quantifies and models the influence of the type and the degree of decomposition of cover crops (CC) on three pesticides sorption: epoxiconazole (EPX), S-metolachlor (SMOC) and glyphosate (GLY). Residues of four cover crop species were incubated for 0, 6, 28 or 56 d in controlled conditions. For each incubation time, adsorption of pesticides on CC residues was measured in batch experiments. Additionally, the biochemical and elemental composition (Van Soest fractionation, C:N, (13)C NMR spectroscopy) of CC was characterized. Mineralization of CC residues was monitored at all incubation times using CO2 trapping. Results showed that the adsorption of pesticides differed significantly according to (i) the type of molecule, (ii) the type of CC, (iii) the degree of CC decomposition and the interaction CC×decomposition time. EPX and GLY were the most (Kd ranging from 188 to 267 L kg(-1)) and the least (Kd ranging from 18 to 28 L kg(-1)) sorbed pesticides respectively. With increasing decomposition of the CC residue, sorption increased by 1.6- to 4.7-fold according to the type of pesticide and cover crop. It was significantly correlated with the net cumulative mineralization (ρ>0.7) and other indicators of biochemical composition such as C:N ratio (ρ<-0.7), the Van Soest neutral detergent soluble fraction (ρ>0.5) and the alkyl/O-alkyl C ratio determined by NMR. An innovative model based on net cumulative mineralization of CC residues is proposed to describe the pesticide sorption and appears to be a promising approach to account for the effects of decaying plant residues on the environmental fate of pesticides.

Comparison of three pesticide fate models with respect to the leaching of two herbicides under field conditions in an irrigated maize cropping system

The ability of three models (PEARL, MACRO and PRZM) to describe the water transfer and leaching of the herbicides S-metolachlor and mesotrione as observed in an irrigated maize monoculture system in Toulouse area (France) was compared. The models were parameterized with field, laboratory and literature data, and pedotransfer functions using equivalent parameterization to better compare the results and the performance of the models. The models were evaluated and compared from soil water pressure, water content and temperature data monitored at 0.2, 0.5 and 1 m depth, together with water percolates and herbicide concentrations measured in a tension plate lysimeter at 1 m depth. Some hydraulic (n, θ(s)) parameters and mesotrione DT50 needed calibration. After calibration, the comparison of the results obtained by the three models indicated that PRZM was not able to simulate properly the water dynamic in the soil profile. On the contrary, PEARL and MACRO simulated generally quite well the observed water pressure head and volumetric water content at the three different depths during wetting periods (e.g. irrigated cropping period) while a poorest performance was obtained for drying periods (fallow period with bare soil and beginning of crop period). Similar water flow dynamics were simulated by PEARL and MACRO in the soil profile although in general, and due to a higher evapotranspiration in MACRO, PEARL simulated a wetter soil than MACRO. For the whole simulated period, the performance of all models to simulate water leaching at 1m depth was poor, with an overestimation of the total water volume measured in the lysimeter (ranging from 2.2 to 6.6 times). By contrast, soil temperature was properly reproduced by the three models. The models were able to simulate the leaching of herbicides at 1m depth in similar appearance time and order of magnitude as field observations. Cumulative observed and simulated mesotrione losses by leaching were consistently higher than the observed and simulated losses of the less mobile herbicide, S-metolachlor. In general, PRZM predicted the highest concentrations for both herbicides in the leachates while PEARL simulated the observed herbicide concentrations better than MACRO and PRZM.

Effect of urban waste compost application on soil near-saturated hydraulic conductivity

Compost application tends to increase soil fertility and is likely to modify soil hydrodynamic properties by acting on soil structural porosity. Two composts, a municipal solid waste compost (MSW) and a co-compost of green wastes and sewage sludge (SGW), have been applied every other year for 6 yr to cultivated plots located on a silt loam soil in the Parisian Basin, France. Four soil zones were defined in the topsoil after plowing: the plowpan located at the base of the plowed layer, compacted (Delta) or noncompacted (Gamma) zones located within the plowed layer, and interfurrows created by plowing and containing a large quantity of crop residues together with the recently-applied compost. To assess the effect of compost application on the near-saturated soil hydraulic conductivity, infiltration rates were measured using a tension disc infiltrometer at three water pressure potentials -0.6, -0.2, and -0.05 kPa in the various zones of the soil profile. Compost addition decreased K((sat)) in the interfurrows after plowing by almost one order of magnitude with average values of 5.6 x 10(-5) m.s(-1) in the MSW plot and 4.1 x 10(-5) m.s(-1) in the SGW plot, against 2.2 x 10(-4) m.s(-1) in the control plot. This effect had disappeared 6 mo after plowing when the average K((sat)) in the control plot had decreased to 1.9 x 10(-5) m.s(-1) while that in the compost-amended plots remained stable.

[Kawasaki disease in a young infant: difficulties for diagnosis and early complications]

We report 1 case of Kawasaki disease in young infant, featuring atypical presentation and severe outcome.

CASE REPORT

A 3-month-old patient was admitted with initial cervical lymphadenitis, and lasting fever. He subsequently developed the classical manifestations of Kawasaki disease. Treatment with intravenous gamma globulins was successful only after a second perfusion. The early echocardiography revealed a coronary vasculitis, which progressed rapidly and was followed by complications as right coronary thrombosis, several aneurysms, and some others as exsudative enteropathy, aseptic meningitis and hepatitis.

CONCLUSION

Patients less than 6 months with Kawasaki disease are at increased risk of atypical presentation, severe prognosis and are often predicted to be non-responsive to the first administration of IVIG.

A long-term view of nutrient transfers through the Seine river continuum

A model (the Riverstrahler model) is used to describe nutrient transfer and transformation at the scale of the whole drainage network of the Seine based on information concerning the basic mechanisms governing N, P and Si inputs to the drainage network and in-stream transformation and retention. It was used to calculate the budget of these nutrients through the whole river continuum from land to sea. With the help of historical documents, the constraints used as forcing function in this model were reconstructed to express the changing conditions of land-use and urban population over the last five hundred years. The corresponding scenarios were run for different hydrological regimes including dry, mean and wet conditions. The results were validated on the long-term series of nutrient measurements spanning more than a century available at some stations on the Seine, upstream and downstream of the city of Paris. The model was also used to explore past and future trends in nutrient loading, retention and delivery to the coastal zone, in response to human management of the terrestrial watershed. Beside the initial pristine state, used as an idealized reference state (with N, P and Si delivered fluxes of about 45-110 kg N km(-2) yr(-1), 2-5 kg P km(-2) yr(-1), 510-1325 kg Si km(-2) yr(-1)), four periods were distinguished. The first one is that of the traditional cottage economy which prevailed, with quite a constant total population, until the end of the 18th century. N, P and Si fluxes were about 235-750 kg N km(-2) yr(-1), 15-60 kg P km(-2) yr(-1) and 425-1280 kg Si km(-2) yr(-1), depending on hydrological conditions. The second period, from the beginning of the 19th century to about the 1950's, corresponded to rapid increase in the total and urban population with a corresponding increase of point sources of N and P. From 1950 onwards, modern farming practices resulted in a dramatic increase in diffuse sources of nitrogen and to a lesser extent phosphorus: riverine N and P export reached 1320-2800 kg N km(-2) yr(-1), and 310-340 kg P km(-2) yr(-1): silica export remained fairly constant at around 410-1260 kg Si km(-2) yr(-1) depending on the hydrological conditions. In the 1990's, the fourth period is represented by a stabilized population and improved wastewater treatment, when the export of phosphorus is reduced to values as low as 40-60 kg P km(-2) yr(-1), but without as effective a reduction of nitrogen export. This represents an unprecedented situation for the marine coastal system, i.e. a shift from nitrogen to phosphorus limitation, as nitrogen is still delivered far in excess of the amount of silica available for diatom blooms.

Impact of rainfall intensity on the transport of two herbicides in undisturbed grassed filter strip soil cores

Two series of displacement experiments with isoproturon and metribuzin herbicides were performed on two undisturbed grassed filter strip soil cores, under unsaturated steady-state flow conditions. Several rainfall intensities (0.070, 0.147, 0.161, 0.308 and 0.326 cm h(-1)) were used. A water tracer (bromide) was simultaneously injected in each displacement experiment. A descriptive analysis of experimental breakthrough curves of bromide and herbicides combined with a modeling analysis showed an impact of rainfall intensity on the solute transport. Two contrasting physical non-equilibrium transport processes occurred. Multiple (three) porosity domains contributed to flow at the highest rainfall intensities, including preferential flow through macropore pathways. Macropores were not active any longer at intermediate and lowest velocities, and the observed preferential transport was described using dual-porosity-type models with a zero or low flow in the matrix domain. Chemical non-equilibrium transport of herbicides was found at all rainfall intensities. Significantly higher estimated values of degradation rate parameters as compared to batch data were correlated with the degree of non-equilibrium sorption. Experimental breakthrough curves were analyzed using different physical and chemical equilibrium and non-equilibrium transport models: convective-dispersive model (CDE), dual-porosity model (MIM), dual-permeability model (DP), triple-porosity, dual permeability model (DP-MIM); each combined with both chemical instantaneous and kinetic sorption.

BM-573, a dual thromboxane synthase inhibitor and thromboxane receptor antagonist, prevents pig myocardial infarction induced by coronary thrombosis

The aim of this study was to characterize the effects of BM-573 [N-terbutyl-N'-[2-(4'-methylphenylamino)-5-nitro-benzenesulfonyl] urea], a novel dual thromboxane A2 receptor antagonist and thromboxane synthase inhibitor, on myocardial infarction induced by topical ferric chloride (FeCl3) application to the left anterior descending (LAD) coronary artery in anesthetized pigs. All control animals (n = 6) developed an occlusive thrombus in the LAD coronary artery. The mean infarct size, revealed by triphenyl tetrazolium chloride (TTC), and the area at risk, evidenced by Evans blue, corresponded to 35.3 +/- 2.2 and 36.9 +/- 2.1% of the left ventricular mass, respectively. In the BM-573-treated group (n = 6), a drug infusion (10 mg. kg-1. h-1) started 30 min before FeCl3 application and continued throughout the experimentation. Among the BM-573-treated group, four pigs did not develop coronary artery thrombus and their myocardium appeared healthy. Histopathological examination of FeCl3-injured coronary artery revealed an occlusive and adherent thrombus in control group, while pretreatment with BM-573 prevented thrombus formation. In infarcted zones, lack of desmin staining and muscle structure disorganization were obvious. Depletion of myocardial ATP content was observed in the myocardial necrotic region of the control group, but not in myocardial samples of BM-573-treated pigs that did not develop myocardial infarction. When BM-573 prevented LAD artery occlusion, the area under the curve of plasmatic troponin T was reduced by 77% over 6 h. These data suggest that BM-573 could be useful for the prevention of myocardial infarction.

Effects of U-46619 on pulmonary hemodynamics before and after administration of BM-573, a novel thromboxane A2 inhibitor

We studied the effects on pulmonary hemodynamics of U-46619, a thromboxane A2 (TXA2) agonist, before and after administration of a novel TXA2 receptor antagonist and synthase inhibitor (BM-573). Six anesthetized pigs (Ago group) received 6 consecutive injections of U-46619 at 30-min interval and were compared with six anesthetized pigs (Anta group) which received an increasing dosage regimen of BM-573 10 min before each U-46619 injection. Consecutive changes in pulmonary hemodynamics, including characteristic resistance, vascular compliance, and peripheral vascular resistance, were continuously assessed during the experimental protocol using a four-element Windkessel model. At 2 mg/kg, BM-573 completely blocked pulmonary hypertensive effects of U-46619 but pulmonary vascular compliance still decreased. This residual effect can probably be explained by a persistent increase in the tonus of the pulmonary vascular wall smooth muscles sufficient to decrease vascular compliance but not vessel lumen diameter. Such molecule could be a promising therapeutic approach in TXA2 mediated pulmonary hypertension as it is the case in pulmonary embolism, hyperacute lung rejection and endotoxinic shock.

Effects of BM-573, a novel thromboxane A2 inhibitor, on pulmonary hemodynamics in endotoxic shock

Thromboxane A2 is considered to be partially responsible for the increase in pulmonary vascular resistance observed after endotoxin administration and to participate in proinflammatory reactions. The effects of a novel dual TXA2 synthase inhibitor and TXA2 receptor antagonist (BM-573) on pulmonary hemodynamics were investigated in endotoxic shock. 30 mins before the start of a 0.5 mg/kg endotoxin infusion, 6 pigs (Endo group) received a placebo infusion and 6 other pigs (Anta group) received a BM-573 infusion. In Endo group, pulmonary artery pressure increased from 25 +/- 1.8 (T0) to 42 +/- 2.3 mmHg (T60) (p < 0.05) after endotoxin infusion while, in Anta group, it increased from 23 +/- 1.6 (T0) to 25 +/- 1.5 mmHg (T60). This difference is due to a reduction in pulmonary vascular resistance in Anta group while pulmonary arterial compliance changes in Endo group remained comparable with the evolution in Anta group. In Endo group, PaO2 decreased from 131 +/- 21 (T0) to 74 +/- 12 mmHg (T300) (p < 0.05), while in Anta group, PaO2 was 241 +/- 31 mmHg at the end of the experimental period (T300). These results demonstrate that TXA2 plays a major role in pulmonary vascular changes during endotoxin insult. Concomitant inhibition of TXA2 synthesis and of TXA2 receptors by BM-573 inhibited the pulmonary vasopressive response during the early phase of endotoxin shock as well as the deterioration in arterial oxygenation.

Evaluating non-equilibrum herbicides transport in undisturbed grassed buffer strips soil columns

Possible contamination of water resources by applied pesticides (including insecticides and herbicides) is a problem currently. Grassed buffer strips have been considered to limit pesticide transfer to surface waters by reducing run-off and erosion. As reduction of run-off mainly involves infiltration in the grassed strip soils, possibility of groundwater contamination by rapid transfer of pesticides via the numerous root channels and macropores presents in grassed soils can not be excluded so far. The beneficial impact of high pesticide retention in the superficial horizons of these soils, related to their high organic matter content, could therefore be strongly reduced by the occurrence of preferential flows. Displacement studies on leaching of bromide (water tracer) and two herbicides, metribuzin (weakly adsorbed) and isoproturon (moderately adsorbed) were conducted in two undisturbed soil columns (length 30 cm, diameter 14 cm) collected from La Jaillière (Loire Atlantique, France) under non saturated conditions. The infiltration fluxes, delivered through a rainfall simulator, were 1.5 and 3 mm/h for one of the columns and 0.6, 1.5 and 3 mm/h for the second column. We obtained asymmetrical shapes of the breakthrough curves, with early breakthrough and increased tailing, qualitatively indicating the presence of preferential flow and confirming the risk of pesticide vertical transport through grassed strips superficial soil horizons. The results showed that leaching of both herbicides increased with the intensity of rainfall applied. This could be explained by a decrease of herbicides sorption due to a lower residence time in the soil.

Pharmacology of the thromboxane receptor antagonist and thromboxane synthase inhibitor BM-531

BM-531 (N-tert-butyl-N'-[(2-cyclohexylamino-5-nitrobenzene)sulfonyl]urea), a torasemide derivative, is a novel noncarboxylic thromboxane receptor antagonist and thromboxane synthase inhibitor. Indeed, its affinity for human washed platelet TXA2 receptors labeled with [3H]SQ-29548 (IC50 = 0.0078 microM) is higher than sulotroban (IC50 = 0.93 microM) and SQ-29548 (IC50 = 0.021 microM). Moreover, BM-531 is characterized by a potent antiaggregatory property. Indeed, on one hand, in human citrated platelet-rich plasma BM-531 prevents platelet aggregation induced by arachidonic acid (600 microM) (ED100 = 0.125 microM), U-46619, a stable TXA2 agonist (1 microM) (ED50 = 0.482 microM) or collagen (1 microgram/mL) (percentage of inhibition: 42.9% at 10 microM) and inhibits the second wave of ADP (2 microM)-induced aggregation. On the other hand, when BM-531 is incubated in whole blood from healthy donors, the closure time measured by the recently developed platelet function analyser (PFA-100) is significantly prolonged. In addition, at the concentrations of 10 and 1 microM, BM-531 totally prevents the production of TXB2 by human platelets activated by arachidonic acid. Finally, at 10 microM, BM-531 significantly prevents rat fundus contractions induced by U-46619 but not by prostacyclin. These results suggest that BM-531, which is devoid of the diuretic property of torasemide, can be regarded as a promising antiplatelet agent.

Degenerated pIX-IVa2 adenoviral vector sequences lowers reacquisition of the E1 genes during virus amplification in 293 cells

A critical issue for E1-deleted adenoviral vectors manufactured from 293 cells is the emergence of replication-competent adenovirus (RCA). These contaminants arise through homologous recombination between identical sequences framing the E1 locus displayed by 293 cells, and the vector backbones. Modified recombinogenic sequences (syngen) were thus introduced within the vector backbone, and virus viability and RCA emergence were assessed. Syngen#1 is a synthetic sequence displaying silent point mutations in the pIX and IVa2 coding regions. A side by side comparison of Ad5CMV/p53 (E1-deleted adenovirus expressing the p53 tumor suppressor gene) and AVdeltaE1#1CMV/p53 (with syngen#1 in place of wild-type sequences) demonstrated a normal productivity for the modified construct. The altered sequences did not impair p53-mediated apoptosis in a model tumor cell line. Most importantly, a statistically significant decrease in terms of RCA occurrence could also be demonstrated. Degenerescence of the recombinogenic sequences could be further accentuated by modifying noncoding pIX region (syngen #2), with no effect on virus productivity and stability. We concluded that these vector modifications constitute a feasible strategy to reduce RCA emergence during amplification in 293 cells. This approach could also be applied to decrease reincorporation of the E1 genes during amplification of deltaE1deltaE4 vectors in 293/E4-trans-complementing cells.

[Primary hypothyroidism in the adult older than 60 years. Characteristics and follow-up after initiation of replacement treatment in hospital]

OBJECTIVE

Primary hypothyroidism is common in the elderly. Yet its care remains unclear.

PATIENTS AND METHODS

Clinical, biological characteristics and outcome of 45 patients aged over 60 years admitted for in-hospital initiation of treatment for primary hypothyroidism were recorded. Causes and tolerance of treatment (clinical and ECG monitoring in hospital) were seek for.

RESULTS

Initial symptoms, predominantly fatigue (84.4%), were moderate, contrasting with severe biological hormonal deficiency. The most common routine biological change was hypercholesterolemia (57.6%). Female predominance was obvious (77.8%) and the most usual aetiology autoimmune chronic thyroiditis. Despite variability of symptoms, long term follow-up demonstrates a positive response to treatment, including an improvement in fatigue, eye-lid swelling, bradycardia and overweight. This clinical improvement was achieved on an average dose of 1.22 +/- 0.47 mg/kg/day L-T4 in order to maintain normal TSH (3.76 +/- 2.93 mUI/l). Cardiovascular incidents while starting treatment require experienced care and low dose initial treatment.

CONCLUSION

Primary hypothyroidism is still lately discovered in the elderly. Yet, since treatment is efficacious and simple, the disease should be searched for and cared after whenever a related symptom occurs.

Complete atherosclerosis regression after human ApoE gene transfer in ApoE-deficient/nude mice

The apolipoprotein E (apoE)-deficient mouse is a relevant animal model of human atherosclerosis. Although the prevention of atherosclerosis development has been documented after somatic gene transfer into animal models, regression of lesions remains to be demonstrated. Thus, we used this genetically defined mouse model nn the nude background to show atherosclerosis regression. ApoE-deficient nude mice were infected with 5 x 10(8) or 10(9) plaque-forming units of a first-generation adenovirus encoding human apoE cDNA. The secretion of human apoE resulted in a rapid decrease of total cholesterol, which normalized the hypercholesterolemic phenotype within 14 days (from 600+/-100 to <100 microg/mL). Transgene expression was observed during a period of >4 months, with a normalization of cholesterol and triglyceride levels during 5 months. At that time, we successfully reinjected the recombinant adenovirus and observed the appearance of the human protein as well as the correction of lipoprotein phenotype. In mice killed 6 months-after the first infection, we observed a dose-dependent regression of fatty streak lesions in the aorta. We showed sustained expression of a transgene with a first-generation adenoviral vector and a correction of dyslipoproteinemia phenotype leading to lesion regression. These data demonstrate that somatic gene transfer can induce plaque regression.

Response of leucine metabolism to hyperinsulinemia in hypothyroid patients before and after thyroxine replacement

We have investigated the effect of hypothyroidism and insulin on protein metabolism in humans. Six hypothyroid patients were studied in a postabsorptive state before and after 5 months of regular treatment for hypothyroidism (153 +/- 17 microg/day of L-T4). The effect of insulin was assessed under hyperinsulinemic euglycemic and eukalemic conditions. Insulin was infused for 140 min at 0.0063 +/- 0.0002 nmol/kg x min. An amino acid infusion was used to blunt insulin-induced hypoaminoacidemia. Whole body protein turnover was measured using L-[1-13C] leucine. When compared to L-T4-induced subclinical thyrotoxic state, hypothyroidism induced a significant decrease (P < 0.05) in leucine endogenous appearance rate (a reflection of proteolysis; 0.89 +/- 0.09 vs. 1.33 +/- 0.05 micromol/kg x min), oxidation (0.19 +/- 0.02 vs. 0.25 +/- 0.03 micromol/kg x min), and nonoxidative disposal (a reflection of protein synthesis; 0.87 +/- 0.11 vs. 1.30 +/- 0.05 micromol/ kg x min). Insulin lowered proteolysis during both the subclinical thyrotoxic and hypothyroid states. Hypothyroidism impaired the antiproteolytic effects of insulin. Thyroid hormones are, therefore, essential for the normal antiproteolytic action of insulin.

Apolipoprotein A-I (R151C)Paris is defective in activation of lecithin: cholesterol acyltransferase but not in initial lipid binding, formation of reconstituted lipoproteins, or promotion of cholesterol efflux

ApoA-I(R151)Paris is a natural apolipoprotein (apo) A-I variant that is associated with low levels of high-density lipoprotein cholesterol (HDL-cholesterol) and the partial deficiency of lecithin:cholesterol acyl-transferase (LCAT) in the plasma of heterozygous carriers. We compared the abilities of recombinant normal apoA-I and recombinant apoA-I(R151C)Paris to clear an emulsion of dimyristoylphosphatidylcholine (DMPC), to form reconstituted lipoproteins with dipalmitoylphosphatidylcholine (DPPC), to activate LCAT, and to promote efflux of biosynthetic cholesterol from porcine aortic smooth muscle cells (SMCs) or of exogenous cholesterol from lipid-loaded mouse peritoneal macrophages. Recombinant apoA-I(R151C)Paris occurred in monomeric and dimeric forms at a ratio of 60:40. Normal apoA-I and apoA-I(R151C)Paris cleared DMPC emulsions at equal rates. Both isoforms associated completely with DPPC during cholate dialysis. Normal apoA-I formed one single particle with a mean diameter of 9.3 nm, whereas apoA-I(R151)Paris gave rise to three particles with mean diameters of 9.3 nm (containing 74% of apoA-I), 10.6 nm, and 12.1 nm, respectively. Compared to normal apoA-I, apoA-I(R151C)Paris had a reduced LCAT-cofactor activity with a 60% lower Vmax/Km ratio due to a 50% higher affinity constant, Km. During incubations for 10 min and 360 min, normal apoA-I/DPPC complexes and apoA-I(R151C)Paris/DPPC complexes were equally efficient in releasing biosynthetic cholesterol from SMCs. In the lipid-free form, apoA-I(R151C)Paris induced normal hydrolysis of cholesteryl esters and normal cholesterol efflux from lipid-loaded mouse-peritoneal macrophages. In conclusion, in addition to its ability to form homo- and heterodimers, apoA-I(R151C)Paris is characterized by defective LCAT-cofactor activity but by normal lipid binding and cholesterol-efflux-promoting abilities.

[Carbimazole and leukocytoclastic vasculitis: apropos of a case]

INTRODUCTION

The authors describe the case of biopsy-proven cutaneous leukocytoclastic vasculitis secondary to treatment with carbimazole.

EXEGESIS

A 78-year-old white female developed erythematous macules on the lower limbs which cleared after discontinuation of her current treatment and implementation of oral steroid therapy. Causal explorations (lack of systemic disorder or infectious disease) remain negative, except for positive immune complexes. This case clearly differs from the two cases of microvasculitis (myositis and nephritis) secondary to treatment with carbimazole previously mentioned in the literature.

CONCLUSION

To our knowledge this is the first report of biopsy-proven cutaneous leukocytoclastic vasculitis associated with this antithyroid agent. Its widespread use makes awareness of the side-effect important.

Somatic gene transfer of human ApoA-I inhibits atherosclerosis progression in mouse models

BACKGROUND

Apolipoprotein (apo) A-I is the major component of HDL, and it displays antiatherogenic properties.

METHODS AND RESULTS

The human apoA-I gene has been transferred into different mouse models by use of a recombinant adenovirus under the control of an RSV-LTR promoter (AV RSV apoA-I). Administration of AV RSV apoA-I to C57BL/6 mice resulted in moderate expression of human apoA-I for 3 weeks, leading to a transient elevation (40% at day 11 after injection) of HDL cholesterol concentration. In contrast, administration of AV RSV apoA-I to human apoA-I-transgenic mice induced a large increase of human apoA-I and HDL cholesterol concentrations (300% and 360%, respectively, at day 14 after injection) for 10 weeks, indicating that an immune response to the transgene was one major hurdle for long-term duration of expression. Recombinant adenovirus expressing human apolipoprotein A-I (AV RSV apoA-I) was also injected into human apoA-I-transgenic/apoE-deficient mice, which are prone to develop atherosclerosis. Over a 6-week period, overexpression of human apoA-I inhibited fatty streak lesion formation by 56% in comparison with control.

CONCLUSIONS

Somatic gene transfer of human apoA-I prevents the development of atherosclerosis in the mouse model.

Enhanced lipolysis in normal mice expressing liver-derived human lipoprotein lipase after adenoviral gene transfer

The authors previously demonstrated that the gene for human lipoprotein lipase (hLPL), an enzyme crucial to the breakdown of triglyceride (TG)-rich dietary fats, corrects the hypertriglyceridemia in lipoprotein lipase (LPL)-deficient knockout mice after adenoviral (Ad)-mediated LPL gene transfer. They have now extended their observations to primary cultured mouse hepatocytes and intact animals of normal LPL genotype, and confirm effective overexpression of hLPL from the liver and a sustained TG-lowering effect in plasma over 60 days. A typical first-generation Ad-vector containing the hLPL cDNA (Ad-LPL) resulted in efficient gene transfer into isolated mouse hepatocytes and significant de novo synthesis of active hLPL protein. In this experiment, 5 x 10(9) viral particles (5 x 10(7) pfu) of either Ad-LPL or an Ad-LacZ control vector were injected into CD1 mice of normal LPL genotype. Hepatic expression of hLPL was confirmed at Day 7 postinjection by in situ hybridization and direct measurement of LPL in the liver. This correlated with a total LPL activity (human + mouse) in postheparin plasma (PHP) of 1020.5 standard deviation [SD] 93.6 mU/mL, versus 479.5 SD 129.7 mU/mL (p < 0.001) in Ad-LacZ controls at Day 7. Respective hLPL activity comprised 49% of the total. Significantly raised levels of hLPL protein mass persisted until Day 60. Corresponding plasma TGs decreased to 39% of Ad-LacZ controls at Day 7, and, despite absent hLPL activity from Day 28 on, serum TGs remained significantly lower in Ad-LPL mice up to Day 42. Fast phase liquid chromatography analysis showed a dramatic depletion in TG-rich lipoproteins, mainly very low density lipoproteins (VLDL) and chylomicron fractions. Therefore, Ad-mediated overexpression of hepatic LPL was found to significantly decrease plasma TG levels unrelated to primary LPL deficiency.

Correction of hypertriglyceridemia and impaired fat tolerance in lipoprotein lipase-deficient mice by adenovirus-mediated expression of human lipoprotein lipase

Humans homozygous or heterozygous for mutations in the lipoprotein lipase (LPL) gene demonstrate significant disturbances in plasma lipoproteins, including raised triglyceride (TG) and reduced HDL cholesterol levels. In this study we explored the feasibility of adenovirus-mediated gene replacement therapy for LPL deficiency. A total of 5 x 10(9) plaque-forming units (pfu) of an E1/E3-deleted adenovirus expressing either human LPL (Ad-LPL) or the bacterial beta-galactosidase gene (Ad-LacZ) as a control were administered to mice heterozygous for targeted disruption in the LPL gene (n = 57). Peak expression of total postheparin plasma LPL activity was observed at day 7 in Ad-LPL mice versus Ad-LacZ controls (834 +/- 133 vs 313 +/- 89 mU/mL, P < .01), and correlated with human-specific LPL activity (522 +/- 219 mU/mL) and mass (9214 +/- 782 ng/mL), a change that was significant to 14 and 42 days, respectively. At day 7, plasma TGs were significantly reduced relative to Ad-LacZ mice (0.17 +/- 0.07 vs 1.90 +/- 0.89 mmol/L, P < .01) but returned to endogenous levels by day 42. Ectopic liver expression of human LPL was confirmed by in situ hybridization analysis and from raised LPL activity and mass in liver homogenates. Analysis of plasma lipoprotein composition revealed a marked decrease in VLDL-derived TGs. Severely impaired oral and intravenous fat-load tolerance in LPL-deficient mice was subsequently corrected after Ad-LPL administration and closely paralleled that observed in wild-type mice. These findings suggest that liver-targeted adenovirus-mediated LPL gene transfer offers an effective means for transient correction of altered lipoprotein metabolism and impaired fat tolerance due to LPL deficiency.

Recombinational construction in Escherichia coli of infectious adenoviral genomes

A two-step gene replacement procedure was developed that generates infectious adenoviral genomes through homologous recombination in Escherichia coli. As a prerequisite, a human adenovirus serotype 5 (Ad5)-derived genome was first introduced as a PacI restriction fragment into an incP-derived replicon which, in contrast to ColE1-derivatives (e.g., pBR322 or pUC plasmids), is functional in a polA mutant of E. coli. Any modification can be introduced at will following two consecutive homologous recombinations between the incP/Ad5 replicon and the ColE1 plasmid. The overall procedure requires only the in vitro engineering of the ColE1-derivative by flanking the desired modification with small stretches of identical sequences. In the first step, a cointegrate between the tetracycline-resistant incP/Ad5 replicon and the kanamycin-resistant ColE1-derivative is selected by growing the polA host in the presence of both antibiotics. Resolution of this cointegrate is further selected in sucrose growth conditions due to the loss of a conditional suicide marker (the sacB gene of Bacillus subtilis) present in the ColE1 plasmid, leading to unmodified and modified incP/Ad5 replicons that can be differentiated upon restriction analysis. Consecutive rounds of this two-step cloning procedure allowed the introduction of multiple independent modifications within the virus genome, with no requirement for an intermediate virus. The potential of this procedure is demonstrated by the recovery of several E1E3E4-deleted adenoviruses following transfection of the corresponding E. coli-derived genomes in IGRP2 cells.

Efficient adenovirus-mediated ectopic gene expression of human lipoprotein lipase in human hepatic (HepG2) cells

Gene therapy to deliver and express a corrective lipoprotein lipase (LPL) gene may improve the lipid profile and reduce the morbidity and potential atherogenic risk from hypertriglyceridemia and dyslipoproteinemia in patients with complete or partial LPL deficiency. We have used an E1-/E3- adenoviral vector, with an RSV-driven human LPL cDNA expression cassette (Ad-RSV-LPL), to achieve high ectopic LPL gene expression in the human hepatoma cell line HepG2, an accepted hepatocellular model of lipoprotein metabolism. Ad-RSV-LPL transduction of HepG2 cells with a multiplicity of infection (moi) between 12.5 and 100 yielded dose-dependent increments in LPL mass and activity. Peak levels of LPL protein of 2,032.1 +/- 274.5 ng/10(5) cells per ml (mol 100) correlated with increased activity of 92.7 +/- 22.6 mU/10(5) cells per ml relative to negligible LPL levels in Ad-RSV-LacZ (beta-galactosidase) controls. Exogenous LPL expression over a 5-day period peaked at day 3. Susceptibility to inhibition by 1 M NaCl and an anti-LPL monoclonal antibody confirmed that lipase activity was indeed derived from human LPL. Hydrolysis, by LPL-overexpressing HepG2 cells, of TG carried in very-low-density lipoprotein (VLDL) showed that greater than 50% of the triglycerides (TG) disappeared after 4 hr of incubation. These results were compatible with FPLC evidence of a marked reduction in VLDL-TG. These results provide strong in vitro evidence that adenoviral-mediated ectopic expression of the human LPL gene could render hepatic cells capable of VLDL catabolism and thus support the possibility for in vivo adenoviral vector-mediated liver-targeted LPL gene therapy.

Cholesterol, phospholipids and markers of the function of the accessory sex glands in the semen of men with hypercholesterolaemia

The effect of hypercholesterolaemia on the cholesterol and phospholipid content of spermatozoa and seminal plasma was studied. Testosterone and specific markers of the accessory sex glands were also measured. Semen samples from 11 hypercholesterolaemic patients (plasma cholesterol > 6.42 mmol/l, plasma triglycerides < 2 mmol/l) were compared with those of 11 normocholesterolaemic controls (plasma cholesterol < 5.14 mmol/l, plasma triglycerides < 2 mmol/l). Cholesterol, phospholipids and the molar ratio of cholesterol: phospholipids were not significantly different between the two groups of patients either in spermatozoa or in seminal plasma. In hypercholesterolaemic patients the total amount of carnitine in the ejaculate was significantly higher, but there were no significant differences in the levels of acid phosphatase or fructose. There were no significant differences in seminal plasma levels of testosterone in the two groups of subjects. These results suggest that hypercholesterolaemia has no effect on cholesterol and phospholipid levels in spermatozoa and does not cause gross modification of the secretory function of the accessory sex glands.

Relationship between interatrial conduction times and left atrial dimension in patients undergoing atrioventricular stimulation

Interatrial conduction time (IACT) and left atrial dimension (LAD) were determined in 75 patients (41 males, 34 females, mean age 78.2 +/- 7.9 years) undergoing atrioventricular (AV) stimulation. The LAD was measured by M mode echocardiography as the distance between the posterior aortic wall and the posterior left atrial wall. The IACT was determined during a transvenous dual chamber pacemaker implant done under local anesthesia (lidocaine). The spontaneous interatrial conduction time (SIACT) was measured from the intrinsic deflection (ID) of the right atrium recorded in a unipolar mode (unipolar J-shaped lead positioned in the right appendage) to the ID of the left atrium (bipolar esophageal lead, left atrial positive deflection equal to the negative one) during sinus rhythm. The right atrium then was paced at a rate slightly greater than the spontaneous one. The paced interatrial conduction time (PIACT) was measured from the stimulus artifact to the left atrial ID. The PIACT was also measured during incremental right atrial pacing (10 beats/min step increase to 180 beats/min) and, from these measurements, the maximum increase of PIACT (MIPIACT) was deduced. The LAD was measured at 39.5 +/- 8.7 mm, SIACT at 70.3 +/- 24.8 msec, PIACT at 118.8 +/- 27.9 msec, and MIPIACT at 16.5 +/- 16.4 msec. We found highly significant relationships between SIACT and LAD (P = 0.0006, r = 0.39), PIACT and LAD (P = 0.0001, r = 0.45), and MIPIACT and LAD (P = 0.0006, r = 0.38). We also noted that the LAD was greater in patients in whom MIPIACT was > 10 msec than in patients in whom the MIPIACT was negligible (P < 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Voltage dependencies of the effects of chlorpromazine on the nicotinic receptor channel from mouse muscle cell line So18

The effects of chlorpromazine (CPZ) on nicotinic acetylcholine receptor (nAChR) were re-investigated by patch-clamp recordings on a mouse muscle cell line: (1) CPZ decreased the channel-opening frequency and, thus, acted as a closed-channel blocker. This effect was independent of the membrane potential and was consistent with an enhanced desensitization of the nAChR. (2) In addition, CPZ decreased the mean channel open time of the nAChR in a concentration- and voltage-dependent manner and, thus, behaved as an open-channel blocker. The latter effect supports the notion that CPZ binds to a site within the nAChR ionic channel.

The IL-2 receptor present on human embryonic fibroblasts is functional in the absence of P64/IL-2R gamma chain

In this study, we have investigated the IL-2R gamma gene expression in several human embryonic fibroblasts which express other components of the IL-2 receptor (IL-2R). Polymerase chain reaction did not allow us to detect IL-2R gamma transcripts in these cells but the functionality of the IL-2R alpha beta was not affected. Indeed, in the human IL-2R alpha+beta+gamma- embryonic lung fibroblasts ICIG-7, IL-2 induced identical phenomena to those previously reported in lymphoid cells: rapid internalization of the IL-2R alpha beta-IL-2 complex, specific phosphorylation of cellular proteins (56 and 38 kDa) and up-regulation of ICAM-1 expression. IL-2 induction of ICAM-1 was only observed in sparse cultures and for IL-2 concentrations over 180 pM. We have also observed, in these fibroblastic cells, the up-regulation of ICAM-2 expression by IL-2, both in sparse and dense cultures. These data show that p64/IL-2R gamma expression in human embryonic fibroblasts does not correlate with the ability of the IL-2R to deliver a biological signal.

Organization of the human CD9 gene

The CD9 antigen was originally described as a 24-kDa molecule present on B-lineage-derived acute lymphoblastic leukemia cells and developing B lymphocytes. Platelets also express a large amount of CD9 antigen and can be activated by CD9 antibodies. We report here the structure of the CD9 gene, which is composed of 8 exons spanning more than 20 kb. There is no TATA or CAAT box in the 5'-flanking domain of the CD9 gene, but a 120-bp region extremely rich in C and G (88%) contains several Sp 1 binding sites and a consensus site for the binding of zinc-finger proteins of the Krox/EGR family. The CD9 antigen belongs to a new cell surface protein family. The organization of its gene closely resembles the organization of the genes for two other members of this protein family, TAPA1 and CD63, which share with CD9 respectively 45 and 25% identity at the amino acid level.

A monoclonal antibody to recombinant human IFN-alpha receptor inhibits biologic activity of several species of human IFN-alpha, IFN-beta, and IFN-omega. Detection of heterogeneity of the cellular type I IFN receptor

A cDNA encoding a 63-kDa human IFN-alpha R (hIFN-alpha R) has recently been cloned. Mouse cells transfected with this cDNA failed to show any signal transmission for IFN-beta, suggesting the involvement of additional chains in the receptor complex. We have expressed in Escherichia coli and COS 7 cells a soluble recombinant protein (sIFN-alpha R) comprising the extracellular domain of the hIFN-alpha R fused at the carboxyl terminus to a sequence of five histidine residues. The sIFN-alpha R was affinity purified and used to generate mAb. One mAb, 64G12, which recognized the cellular receptor as well as the recombinant proteins was found to neutralize the biologic activity of IFN-alpha, -beta, and -omega and natural type I IFN, but not IFN-gamma. To our knowledge, this is the first report of a neutralizing mAb against the human IFN-alpha R. Interestingly, we found that the affinity of this antibody for the cellular receptor depended on the cell line used. These results provide strong evidence that the cloned hIFN-alpha R chain is required for binding and signal transmission of all subspecies of type I IFN and suggest a structural heterogeneity of the receptor at the cell surface.

A monoclonal antibody to recombinant human IFN-alpha receptor inhibits biologic activity of several species of human IFN-alpha, IFN-beta, and IFN-omega. Detection of heterogeneity of the cellular type I IFN receptor

A cDNA encoding a 63-kDa human IFN-alpha R (hIFN-alpha R) has recently been cloned. Mouse cells transfected with this cDNA failed to show any signal transmission for IFN-beta, suggesting the involvement of additional chains in the receptor complex. We have expressed in Escherichia coli and COS 7 cells a soluble recombinant protein (sIFN-alpha R) comprising the extracellular domain of the hIFN-alpha R fused at the carboxyl terminus to a sequence of five histidine residues. The sIFN-alpha R was affinity purified and used to generate mAb. One mAb, 64G12, which recognized the cellular receptor as well as the recombinant proteins was found to neutralize the biologic activity of IFN-alpha, -beta, and -omega and natural type I IFN, but not IFN-gamma. To our knowledge, this is the first report of a neutralizing mAb against the human IFN-alpha R. Interestingly, we found that the affinity of this antibody for the cellular receptor depended on the cell line used. These results provide strong evidence that the cloned hIFN-alpha R chain is required for binding and signal transmission of all subspecies of type I IFN and suggest a structural heterogeneity of the receptor at the cell surface.

Comparison of the damping effect of different shoeing by the measurement of hoof acceleration

The purpose of this study was to compare the damping effect of 16 types of shoeing by measuring hoof acceleration parameters on two trotting horses. At impact, maximal deceleration had extreme values such as 188 m/s2 (+/- 55) for the most damping combination (p < 0.01) and 746 m/s2 (+/- 14) for the steel shoe (mean = 551 m/s2 +/- 125). After the shock, the hoof was exposed to a mean vibrating acceleration at 418 Hz (+/- 84) which was progressively damped in 37.3 ms (+/- 10.5). According to these results, the damping ability of different farriery products significantly reduces (p < 0.05) shocks and vibrations at hoof impact in the athletic horse caused by runs on asphalt or similar surfaces. In practice, the use of the most efficient shoeing should help to reduce the incidence of the over-used joint diseases in the athletic horse caused by runs on hard surfaces.

Length-tension relationship of the posterior deltoid to triceps transfer in C6 tetraplegic patients

We assessed the length-tension relationship of the posterior deltoid to triceps transfer in 8 tetraplegics (n = 11 transfers) and compared the results to the length-tension relationship of the normal triceps measured in a check sample composed of 9 able bodied, right handed women. We designed a device to lock the arm and forearm and used a force transducer to assess the torque output isometrically. The muscle was tested at 6 different lengths (130, 110, 90, 70, 45 and 0 degree of elbow flexion) with the shoulder abducted at 90 degrees. As expected, the transfer behaved differently from the normal triceps. The mean maximum torque recorded was 7.8 Nm in patients while it was 27 Nm in the check sample. When compared, the absolute values (ie values expressed with a dimension of torque) were significantly different between groups (0.00001 < p < 0.002). The expression of this relation (ie the relative values expressed as percentage of maximum values) revealed significant statistical differences (p < 0.002) at 90 and 70 degrees of elbow flexion; the peak torque was recorded at 130 degrees in patients while it was recorded at 110 degrees in the check sample, with a plateau between 110 degrees and 70 degrees. On the other hand, if the length-tension relationship was fairly similar among subjects of the check sample, it exhibited tremendous differences among patients; it seemed that initial tension given by the surgeon represented a variable difficult to control without a device dedicated to that task.

Functional adult acetylcholine receptor develops independently of motor innervation in Sol 8 mouse muscle cell line

We have defined culture conditions, using a feeder layer of cells from the embryonic mesenchymal cell line, 10T1/2 and a serum-free medium, which allow cells from the mouse myogenic cell line Sol 8 to form contracting myotubes for two weeks. Under these culture conditions, Sol 8 myotubes undergo a maturation process characterized by a sequential expression of two phenotypes. An early phenotype is typified by the expression of the nicotinic acetylcholine receptor (AChR) gamma-subunit transcripts and the presence of low conductance ACh-activated channels, typical of embryonic AChR. A late phenotype is characterized by the expression of AChR epsilon-subunit transcripts, the decreased accumulation of gamma-subunit transcripts and the appearance of high conductance ACh-activated channels, typical of adult AChR. These results indicate that the expression of functional adult type AChR does not require the presence of the motor nerve and therefore represents an intrinsic feature of the Sol 8 muscle cells. Chronic exposure of the cells to the voltage-sensitive Na+ channel blocking agent tetrodotoxin does not affect the appearance of the AChR epsilon-subunit transcripts but prevents the reduction of the steady-state level of the AChR gamma-subunit transcripts and yields a reduced proportion of the adult type channels. Thus, activity seems to facilitate the switch from the embryonic to the adult phenotype of the AChR protein. The Sol 8 cell system might be useful to analyse further the genetic and epigenetic regulation of muscle fibre maturation in mammals.

Existence of different subtypes of nicotinic acetylcholine receptors in the rat habenulo-interpeduncular system

Neuronal nicotinic ACh receptors (nAChRs) are present in the rat medial habenula (MHB) and interpeduncular nucleus (IPN), two brain regions connected through the fasciculus retroflexus (FR). The goal of the present study was to compare the electrophysiological and pharmacological characteristics of nAChRs located at pre- and postsynaptic sites within the MHB-IPN system. nAChRs located on the soma of IPN neurons were studied using patch-clamp techniques and a preparation of acutely isolated neurons. Whole-cell currents evoked by Ach and nicotine showed an intense rectification at positive membrane potentials. nAChR channels were relatively nonselective for cations, had a unitary conductance of 35 pS, and were activated by several nicotinic agonists with the following rank order: cytisine greater than ACh greater than nicotine greater than dimethylphenylpiperazinium (DMPP). They were blocked by mecamylamine, hexamethonium, curare, and dihydro-beta-erythroidine (DHBE), but were insensitive to alpha-bungarotoxin and neuronal bungarotoxin. In contrast, nAChRs recorded on the soma of MHB neurons under equivalent experimental conditions exhibited different characteristics for single-channel conductance and agonist and antagonist sensitivity. The pharmacological properties of presynaptic nAChRs in the IPN were analyzed in a rat brain slice preparation. Stimulation of the FR produced a presynaptic afferent volley recorded in the rostral subnucleus of the IPN. Nicotinic agonists decreased the amplitude of the afferent volley with different efficacies: nicotine greater than cytisine greater than ACh greater than DMPP. The action of nicotine was insensitive to alpha-bungarotoxin and to neuronal bungarotoxin, but was blocked by mecamylamine, hexamethonium, curare, and DHBE, with IC50 values different from those reported for IPN postsynaptic nAChRs. This study thus demonstrates the functional diversity of nAChRs in the rat CNS.

[Additional contribution of high amplification electrocardiography in the follow-up of children with muscular dystrophy]

Fifteen children and adolescents with muscular dystrophy underwent investigation by Doppler echocardiography and high amplification electrocardiography to evaluate the quality of left ventricular function. High amplification ECG showed minor intra-atrial conduction defects in 3 cases and abnormal late micro potentials without arrhythmogenic late potentials in 3 other cases. Significant abnormalities were observed in 40% of children examined. Doppler echocardiography showed relative conservation of systolic left ventricular function but a decrease in indices of contractility was observed in 46% of cases, especially in patients with Duchenne muscular dystrophy. Abnormalities of left ventricular distensibility were observed earlier and were more common (53% of cases). A significant decrease in cardiac output was found in 50% of patients, especially among the older and more severely affected children irrespective of the type of muscular dystrophy. These two investigations provide complementary information for the evaluation of left ventricular function of children with muscular dystrophy and they are proposed routinely for the follow-up of these patients.