Polymerization of lactams, 88. Copolymers poly(ϵ-caprolactam)-block-polybutadiene prepared by anionic polymerization,part III. Model polymerizations initiated with potassium salt of ϵ-caprolactam and accelerated with isocyanates and their derivatives

Anionic polymerization of ?-caprolactam was initiated with the potassium salt of ?-caprolactam and accelerated with phenyl isocyanate, toluylene diisocyanate, 4,4′-diphenylmethane diisocyanate, some derivatives of these isocyanates (urethanes, ureas, and allophanates), or combinations of phenyl isocyanate with its derivatives at 150°C. The effect of individual structures on the polymerization kinetics and their contribution to the preparation of block copolymers of ?-caprolactam with hydroxy-terminated prepolymers, in-situ functionalized with diisocyanates, are discussed on the basis of a detailed analysis of time functions of polymer yield and degree of polymerization.     

Pulmonary arterial hypertension associated with systemic sclerosis in the Czech Republic

Background  

Systemic sclerosis (SSc) is an important cause of pulmonary arterial hypertension (PAH), with an estimated prevalence of 7.85–26.7%.     

Patterns of surface temperatures in two mole-rats (Bathyergidae) with different social systems as revealed by IR-thermography

Furred subterranean mammals face the problem of dissipating heat to the environment because high humidity and absence of air flow in sealed belowground tunnels constrain heat loss from body by convection and evaporation. In order to detect body areas responsible for heat loss, surface temperatures in two species of African mole-rats were measured at different ambient air temperatures by infrared thermography. Fur characteristics were also evaluated. Thinner pelage of the ventrum, its moderate temperature and large size suggest that ventral side of the body is the main thermal avenue for heat loss in both species. Interspecific differences could be explained by different fur characteristics connected with social thermoregulation. Compared to the social Fukomys mechowii, the solitary Heliophobius argenteocinereus has denser and longer fur on most of its body; its surface temperature was thus lower than in F. mechowii at lowered ambient temperatures. On the other hand, the denser and longer hair cover in H. argenteocinereus impedes heat dissipation at highest ambient temperatures (and probably also during digging activity) resulting in increase of core body temperature. H. argenteocinereus seems to be more sensitive to overheating than F. mechowii. At lower air temperatures, the social species may uses huddling to combat hypothermia.     

Monotonic Tension-Torsion Experiments and FE Modeling on Notched Specimens Produced by SLM Technology from SS316L

The aim of this work was to monitor the mechanical behavior of 316L stainless steel produced by 3D printing in the vertical direction. The material was tested in the “as printed” state. Digital Image Correlation measurements were used for 4 types of notched specimens. The behavior of these specimens under monotonic loading was investigated in two loading paths: tension and torsion. Based on the experimental data, two yield criteria were used in the finite element analyses. Von Mises criterion and Hill criterion were applied, together with the nonlinear isotropic hardening rule of Voce. Subsequently, the load-deformation responses of simulations and experiments were compared. Results of the Hill criterion show better correlation with experimental data. The numerical study shows that taking into account the difference in yield stress in the horizontal direction of printing plays a crucial role for modeling of notched geometries loaded in the vertical direction of printing. Ductility of 3D printed specimens in the “as printed” state is also compared with 3D printed machined specimens and specimens produced by conventional methods. “As printed” specimens have 2/3 lower ductility than specimens produced by a conventional production method. Machining of “as printed” specimens does not affect the yield stress, but a significant reduction of ductility was observed due to microcracks arising from the pores as a microscopic surface study showed.     

The exposure of nonsmoking and smoking mothers to environmental tobacco smoke during different gestational phases and fetal growth

We studied the impact of maternal exposure to environmental tobacco smoke (ETS) on birth weight (BW), low birth weight (LBW), and intrauterine growth retardation (IUGR) according to self-reported maternal smoking habits in a sample of 6,866 singleton births. We obtained data about parental characteristics and maternal active smoking (AS) and passive smoking at delivery via maternal questionnaires and medical records. We used three categories of smoking habits (nonsmokers and those who smoked 1-10 or >10 cigarettes per day) and defined ETS exposure as greater than or equal to 5 cigarettes per day smoked by others in the mother's presence. We used multiple regression and logistic regression procedures with adjustment for many associated covariates. We observed a significant reduction of the mean BW in infants of AS mothers. This reduction was only marginal for mothers who stopped smoking after recognizing their pregnancy. ETS exposure in 1,797 of 5,507 nonsmoking mothers reduced the mean BW of their infants by 53 g [95% confidence interval (CI), 24-82 g]. ETS exposure also significantly reduced BW in babies of AS mothers by 92 g (CI, 21-113 g) compared with BW of ETS-nonexposed AS mothers. The adjusted odds ratio (AOR) of LBW for ETS-exposed AS mothers was two times the LBW risk of ETS-nonexposed AS mothers(2.02; CI, 1.11-3.67); the AOR of ETS-exposed nonsmoking mothers was 1.51 (CI, 1.02-2.26). The AOR of IUGR for this group did not differ from unity (1.08; CI, 0.82-1.43). However, ETS exposure increased the AOR of IUGR for AS mothers from 1.64 (CI, 1.06-2.53) to 2.13 (CI, 1.70-2.67). ETS exposure reduced the BW of infants of nonsmoking mothers and contributed to additional BW reduction in infants of AS mothers. ETS exposure increased the risk of LBW but not that of IUGR in babies of nonsmoking mothers.     

A randomised controlled trial of intravenous immunoglobulin in IgM paraprotein associated demyelinating neuropathy

This multicentre randomised double blind crossover trial tested the short term efficacy of intravenous immunoglobulin (IVIg) 2.0 g/kg given over 24 or 48 hours in patients with paraproteinaemic demyelinating neuropathy (PDN). Twenty-two patients were randomised and completed the trial. After 2 weeks, the overall disability grade decreased during both IVIg treatment and placebo but neither change was significant nor was the mean difference between the treatment effects. After 4 weeks the overall disability decreased by a mean of 0.55 [0.67] grades during the IVIg period (p = 0.001) while it was substantially unmodified during the placebo period. The mean difference between the treatment effects was significant (p = 0.05). Overall during the IVIg period 10 patients improved and 11 were stable and one got worse. During the placebo period 4 patients improved, 4 deteriorated and 14 were stable. Many secondary outcome measures, including Rankin scale, time to walk 10 metres, grip strength, sensory symptoms score were significantly better during IVIg treatment. Two serious adverse events occurred during the trial, both during placebo treatment. In conclusion the trial showed some short-term benefit of IVIg in about half of the patients confirming previous observation. Received: 6 August 2001, Received in revised form: 6 March 2002, Accepted: 12 March 2002 RID="*" ID="*"The other members of the INCAT group are Jacques Aubry PhD, Institut de Biologie, INSERM Unit 463, 9 Quai Moncousu, 44 035 Nantes, France; Nicole Baumann MD, InSERM Unit 495, Salpetriere Hospital, 75 651 Paris, Cedex 13 France; Robert Hadden PhD, Michael Lunn, MD, Department of Neuroimmunology, Guy's, King's and St. Thomas' School of Medicine, Guy's Hospital, London SE1 9 UL, UK; Martin Knapp Phd, Personal Social Services Research Unit, London School of Economics and Political Science, Houghton Street, London WC2A 1AE, UK; Jean-Marc Léger MD, Pierre Bouche MD, Service d'Eplorations Functionelles de la Salpetriere, 47 Boulevard de l'Hospital, 75 651 Paris, Cedex 13, France; Radim Mazanec CSc, Charles University, 2^nd Medical School, University Hospital, V uvalu 84, Prague 5, Czech Republic; Nicoletta Meucci MD, Institute of Clinical Neurology, University of Milan, Ospedale Maggior-Policlinico, via Sforza, 20 122 Milan, Italy; Frans van der Meché PhD, Department of Neurology, Erasmus Medical Center Rotterdam, dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands; and Klaus Toyka PhD, Universitat Würzburg, Josef-Schneider Strasse 2, 97 080 Würzburg, Germany Correspondence to Giancarlo Comi, MD     

Chromosomal aberrations in lymphocytes of healthy subjects and risk of cancer

There is evidence that increased frequency of chromosomal aberration (CA) in peripheral blood lymphocytes is a predictor of cancer, but further data are needed to better characterize CA as marker of cancer risk. From the archives of 15 laboratories we gathered cytogenetic records of 11,834 subjects who were free of cancer at the moment of blood drawing and who underwent cytogenetic examination for preventive purposes in the Czech Republic during 1975-2000. We linked these records to the national cancer registry, revealing a total of 485 cancer cases. Subjects were classified according to the percentiles of CA distribution within each laboratory as low (0-33rd percentile), medium (34-66th percentile), and high (66-100th percentile). Subjects were further classified by occupational exposure and by subclass of CA. We found a significant association between the overall cancer incidence and the presence of chromosome-type aberrations [relative risk (RR) for high vs. low CA level = 1.24; 95% confidence interval (CI), 1.03-1.50] but not chromatid-type aberrations. Stomach cancer showed a strong association with frequency of total CA (RR = 7.79; 95% CI, 1.01-60.0). The predictivity of CA observed in subjects exposed to various classes of carcinogens did not significantly differ from the group of nonexposed subjects. This study contributes to validation of CA as a predictive marker of cancer risk, in particular, of stomach cancer; the association between CA frequency and cancer risk might be limited to chromosome-type aberrations.     

Association of muscular strength with incidence of metabolic syndrome in men

PURPOSE: To examine the association between muscular strength and incidence of metabolic syndrome. METHODS: Participants were 3233 men (20-80 yr) initially free of metabolic syndrome who had two or more clinical examinations between 1980 and 2003, including baseline muscular strength and cardiorespiratory fitness assessment. Metabolic syndrome was defined according to NCEP-ATP III criteria. Muscular strength was quantified by combining body weight-adjusted one-repetition maximal measures for leg and bench presses. Cardiorespiratory fitness was assessed by maximal treadmill test. RESULTS: A total of 480 men developed metabolic syndrome during a mean follow-up period of 6.7 +/- 5.2 yr. In a Cox regression analysis adjusted for age, the hazard ratios (95% confidence intervals) of metabolic syndrome associated with the incremental categories of muscular strength were 1.00 (referent), 0.88 (0.69-1.12), 0.77 (0.60-0.98), and 0.54 (0.42-0.71), respectively (linear trend P < 0.0001). The inverse trend persisted after adjustment for smoking, alcohol intake, number of baseline metabolic syndrome risk factors, family history of diabetes, hypertension, and premature coronary disease (P = 0.004), but was attenuated (P = 0.06) when further adjusted for cardiorespiratory fitness. Compared with the lowest strength category, the highest strength category was associated with 44 and 39% lower risk (P < 0.05 each) of incident metabolic syndrome among normal weight body mass index (BMI < 25) and overweight or obese (BMI > or = 25) men, respectively. An inverse association of incident rates was also seen within stratum of age (20-39 yr, P < 0.001; 40-49 yr, P < 0.01; and 50+ yr, P < 0.05). CONCLUSIONS: Muscular strength was inversely associated with metabolic syndrome incidence, independent of age and body size. Potential benefits of greater muscular strength presumably through resistance exercise training should be considered in primary prevention of metabolic syndrome.