Polymerization of lactams, 55. Cyclic dimer of 6-caprolactam and its polymerization

Polymerization of the cyclic dimer of 6-caprolactam was investigated in N-methyl-2-pyrroli-done solution at 260°C under initiation with 6-aminocaproic acid or anhydrous phosphoric acid on the one hand, and in the solid phase at 230, 260, and 280°C in the absence of any other component or under initiation with anhydrous phosphoric acid, on the other. Monomeric 6-caprolactam was formed in all cases already at the beginning of reaction. It has been suggested that, in addition to the direct incorporation of the cyclic dimer into a polymer chain, the dimer is alos incorporated via the monomer, which is formed from the dimer by an intermolecular transamidation reaction.     

Polymers containing enzymatically degradable bonds. VI.Hydrophilic gels cleavable by chymotrypsin

New types of hydrophilic gels based on N-(2-hydroxypropyl)methacrylamide which contain oligopeptide sequences in the crosslinks were prepared. These gels are enzymatically degradable by chymotrypsin. The rate of their degradation may be varied within a broad range by changes in the length and detailestructure of the oligopeptide sequence in the crosslinks and by changing their network density.     

Infrared spectra and sequence length distribution in free radical styrene/methacrolein copolymers

The method of azoisobutyronitrile (AIBN)-initiated bulk copolymerization of styrene (S) and methacrolein (M) was employed to determine the monomer reactivity ratios r_S = 0.15 and r_M = 0.55 (Q_M = 1.50, e_M = 0.78). Quantitative IR spectroscopy in the region of 4000–450 cm^?1 was used to elucidate the structure of copolymers. In addition to methacrolein units containing aldehyde groups, the copolymers may also contain cyclic hemiacetal structures formed by the reaction of the carbonyls of the neighboring methacrolein units. The carbonyl absorption at 1722 cm^?1 showed that, up to 30 mole-% methacrolein in the copolymer, almost all methacrolein units have free aldehyde groups. The number of cyclic structures increases with the concentration of methacrolein in the copolymer. The experimental data are in agreement with the statistical theory on the sequence length distribution. The shift of the styrene band at 540 cm^?1 to higher wavenumber was investigated and related to the shortening of sequence length of the styrene units. The intensity of the styrene band at 760 cm^?1 was related with the distribution of the MSM triads and the copolymer structure.     

Telomere-specific fluorescence in situ hybridization analysis of couples with five or more recurrent miscarriages

Fluorescence in situ hybridization analysis using telomere specific probes has been used to detect cryptic translocations in the chromosomal telomeric regions. This study was performed in five clinically normal couples who have had five or more spontaneous abortions and whose karyotypes were found to be normal using conventional cytogenetic techniques. Using the telomere specific probes, in one couple we determined a cryptic translocation between chromosome 3 and 10, and, in another couple, the signal in chromosome 20 was detected in another chromosome, which was probably a D group chromosome. Additionally, in the latter and also in two other couples, we observed a polymorphism. The approach will be helpful for screening cryptic translocations using telomere specific multiple probe sets in couples with recurrent miscarriages. As prenatal diagnosis will be available for these couples for future pregnancies, it will be possible to help these families to have healthy fetuses.     

The relationship between muscle kinetic parameters and kinematic variables in a complex movement

Summary Kinematic variables of the vertical jump (jumping height, jump phase durations and joint angles) were measured on 39 male physical education students. In addition, kinetic parameters of the hip and knee extensors, and of the plantar flexors (maxima voluntary force and its rate of development) were recorded on the same subjects, in isometric conditions. The results demonstrated significant positive correlations between kinetic parameters of the active muscle groups and jumping height (r=0.217−0.464). The dominant effect on these correlations was due to the knee extensors. Correlations between these parameters and the duration of the jump phases were much weaker. Correlation coefficients between kinetic parameters and limb angles in the lowest body position showed that fast force production in one muscle group was related to a significant decrease in the joint angles of distant body segments. Multiple correlation coefficients between leg extensor parameters and kinematic variables (ranging between 0.256 for the duration of the counter-movement phase and 0.616 for jump height) suggested that kinetic parameters could explain more than a quarter of the variability of this complex human movement. Therefore, the conclusion was drawn that an extended set of measurements of the relevant musculo-skeletal system parameters could predict a considerable amount of the variability of human movement. However, high correlation coefficients between the same kinetic parameters of different muscle groups suggest that not all active muscle groups have to be included in the measurements.     

The direct early diagnosis of cystic fibrosis by the detection of the deltaF508 CFTR gene mutation in a prematurely delivered boy

The suspicion of prenatal meconium ileus syndrome was raised in a pregnancy in a family with no history of cystic fibrosis because of significantly higher maternal serum alpha-fetoprotein in the 16th and 19th week of gestation, dispersed areas with increased echogenity in the fetal abdomen, slight fetal ascites in the 24th-25th weeks of gestation, decreased amniotic fluid gamma-glutamyltranspeptidase (GGT) activity and alpha-fetoprotein level in the 25th-26th weeks, and normal 46,XY karotype of the fetus. The detection of a homozygous deltaF508 cystic fibrosis transmembrane regulator (CFTR) gene mutation, by means of PCR from a small amount of white blood cells and urine sediment cells, substantiated the diagnosis of cystic fibrosis in a prematurely delivered boy in the 28th week of gestation. The repeated sweat test was unsuccessful. The autopsy examination confirmed the diagnosis of cystic fibrosis. Fetal meconium ileus syndrome was complicated by peritonitis and by formation of a meconium pseudocyst. Direct PCR typing improves postnatal diagnostic possibilities in the early neonatal period in prematurely delivered babies when the sweat test is difficult to perform.     

Poly(D,L-lactide/epsilon-caprolactone)/hydroxyapatite composites as bone filler: an in vivo study in rats

In this study, a novel composite bone substitute was implanted in animal models (rats) and their in vivo characteristics were examined. A D,L-lactide and E-caprolactone copolymer (Mw: 80,000; Mn:40,000, and PI:2.00) was synthesized by ring-opening polymerization of the respective dimers using stannous octoate as the catalyst. The final ratio of D,L-lactide to epsilon-caprolactone obtained by 1NMR was 60/40. Hydroxyapatite (HA) powder was loaded in the copolymer. The HA/copolymer ratio was 60/40 (w/w). These composites were easily shaped by hand. Animal tests were performed on mature wistar rats (n=30). Defects were created on the proximal, the thickest part of the femur. The bone defects of the first group were filled with polymer/HA composite, the second group filled with only HA and the third group was left empty. Histologic examination of bone tissues showed new bone formation around the yellow-green polymer/HA composite material in the first group of animals whereas no evidence of new bone growth was observed in other groups.     

Strain differences in peritoneal macrophage activity and susceptibility to experimental allergic encephalomyelitis induction in rats

The objective of the present study was to investigate the relevance of peripheral macrophage activity for the susceptibility to the induction of experimental allergic encephalomyelitis (EAE). Rats of EAE-susceptible Dark Agouti and EAEresistant Albino Oxford strain were immunized with guinea pig spinal cord homogenate (DA_GPSC and AO_GPSC), while non-immunized rats served as controls (DA_NIM, AO_NIM). On day 15 after immunization rats were sacrificed and their peritoneal macrophages tested for adherence capacity, zymosan phagocytosis and respiratory burst. Macrophages from AONIM rats exhibited lower adherence capacity and higher phagocytosis and H₂O₂ production when compared to macrophages from DANIM rats. Immunization with GPSC decreased adherence and phagocytosis and increased H₂O₂ production in macrophages from AO rats, but did not influence these activities in macrophages from DA rats. The results from the present study suggest that inflammatory activities of macrophages from AO rats could be considered as regulatory mechanisms connected with the resistance to EAE induction.     

Autoimmunity to Polymorphonuclears: Functional Consequences of the Binding of Antibodies to Membrane and Cytoplasmic Target Antigens of Polymorphonuclear Leukocytes

Antineutrophil autoantibodies reacting with cytoplasmic antigens are associated with various types of vasculitides, whereas antibodies reacting with neutrophil membrane antigens are mostly related to autoimmune neutropenias. The aim of this study was the investigation of the effect of monoclonal antibodies (MoAbs) reacting with surface and cytoplasmic antigens of polymorphonuclear leukocytes (PMN) known to be targets for autoantibodies in human diseases. Blood of healthy volunteers was tested for several phagocytic functions in the presence of MoAbs against surface (CD16, GD11b, CD18, NB1) and cytoplasmic (proteinase 3; PR3) molecules. Candidacidal activity was significantly inhibited in the presence of all MoAbs but isotypic control. Phagocytic activity was inhibited by anti-CD11b and/or anti-CD18 MoAbs. Zymosan-induced chemiluminescence was reduced by MoAbs anti-CD16, CD18, and NB1, enhanced by anti-PR3 MoAb, and less enhanced by anti-CD11b. In conclusion, antimembrane antibodies diminished phagocytic functions at multiple steps; in contrast, anticytoplasmic MoAb promoted activation of oxidative burst in addition to impairment of microbicidal activity. This fact may be related to different pathogenic aspects of diseases associated with antimembrane and anticytoplasmic antibodies.     

Work-induced potassium changes in skeletal muscle and effluent venous blood assessed by liquid ion-exchanger microelectrodes

Using liquid ion-exchanger semimicroelectrodes with a side pore, we measured changes of extracellular potassium concentration (K_e ⁺) in adult rabbit and cat gastrocnemius muscles and in venous effluent blood flowing from the cat gastrocnemius muscle during various bouts of activity induced by sciatic nerve stimulation.