Hemocompatibility of PMEA coated oxygenators used for extracorporeal circulation procedures

An inflammatory response to cardiopulmonary bypass (CPB) caused by bioincompatibility of extracorporeal circuits is one of the major clinical issues in cardiac surgery. Recently a new coating material, poly-2-methoxyethylacrylate (PMEA), was developed to improve the biocompatibility of blood contacting surfaces. In a simulated cardiopulmonary bypass model, using fresh human whole blood, 15 membrane oxygenators (Capiox SX18, Terumo Corp., Tokyo, Japan) were compared. Five of them had the PMEA coating, five had a heparin-coated surface, and five had no surface treatment. Blood samples were taken at several time-points during a 90 minute circulation period. Changes in coagulation, complement, and blood cell alteration factors were measured by ELISA methods, plasma bradykinin levels were measured by radioimmunoassay, and expression of genes encoding cytokines TNF-alpha, interleukin-1beta, interleukin-6, and interleukin-8 was determined by semiquantitative real time RT-PCR. Platelet adhesion was significantly reduced in both the PMEA and the heparin coated circuits. Release of platelet activation marker beta-thromboglobulin was significantly higher in the uncoated control group (p < 0.01). After 5 minutes of blood circulation bradykinin levels significantly increased in all three groups (p < 0.01); however, the group with the PMEA coated oxygenators showed the lowest values. Expression of genes encoding proinflammatory cytokines in monocytes was increased in all groups, with the lowest being in the PMEA coated group. PMEA coated CPB surfaces in an in vitro experimental model showed an improved thrombogenicity, reduced bradykinin release, less platelet activation and less proinflammatory cytokines gene expression in comparison with a noncoated group. The authors assume that PMEA coating may ameliorate some of intra- and postperfusion syndromes, particularly hypotension, unspecific inflammation, hyperfibrinolysis, and blood loss.     

Cytomegalovirus transmission to preterm infants during lactation.

Breastfeeding has a major impact on HCMV epidemiology. The incidence of postnatal HCMV reactivation during lactation equals the maternal seroprevalence. Infectious virus, viral DNA and RNA can be isolated easily from cell and fat-free milk whey. Early onset of viral DNAlactia and virolactia as well as high viral load in milk whey are maternal risk factors for virus transmission. The dynamics of HCMV reactivation can be described by unimodal kinetics with interindividual variation. Virus reactivation during lactation is a self-limiting local process in the absence of systemic HCMV infection. Preterm infants below 1000g birthweight and a gestational age below 30 weeks may be at high risk of acquiring a symptomatic HCMV infection. Several recent studies described low transmission rates and mostly asymptomatically infected neonates using frozen milk. Despite different freeze-storing procedures, HCMV transmissions occurred, and severe HCMV infections were observed. Few data exist on the long-term outcome of postnatally acquired HCMV infection via breast milk. To substantiate the international debate on the use of native or inactivated milk for feeding of preterm infants, additional data are necessary for better identification of mother-infant-pairs at risk for viral transmission and symptomatic infection early after birth.     

Stimulation of colonic anion secretion by monochloramine: action sites

During inflammatory bowel disease, reactive oxygen metabolites are released by phagocytes reacting with intraluminal NH₃ to produce monochloramine (NH₂Cl). NH₂Cl is assumed to play role in the pathogenesis of inflammation-associated diarrhoea, as it is able to induce intestinal secretion. The aim of the present study was to determine the action sites of NH₂Cl in rat colonic epithelium with Ussing chamber and fura-2 experiments. In intact mucosa, NH₂Cl (5·10^–6–10^–4 mol·l^–1) evoked a concentration-dependent increase in short-circuit current (I_sc), consistent with the induction of anion secretion, as demonstrated by anion substitution and transport blocker experiments. When the apical membrane was permeabilised by the ionophore nystatin, two basolateral action sites of NH₂Cl (5·10^–5 mol·l^–1) could be identified, i.e. an increase in the K⁺ conductance and a stimulation of the Na⁺–K⁺ pump. When tissues were basolaterally depolarised by a high K⁺ concentration, the stimulation of an apical Cl^– conductance by NH₂Cl was observed. In isolated colonic crypts loaded with the Ca²⁺-sensitive fluorescent dye fura-2, NH₂Cl (5·10^–5 mol·l^–1) evoked an increase in the intracellular Ca²⁺ concentration. This increase was independent from the presence of Ca²⁺ in the extracellular medium, but was inhibited by blockade of intracellular sarcoplasmatic, endoplasmatic Ca²⁺-ATPases with cyclopiazonic acid (10^–5 mol·l^–1). The NH₂Cl-evoked Ca²⁺ release was sensitive against inhibition of ryanodine receptors with ruthenium red (5·10^–5 mol·l^–1) and against inhibition of inositol-1,4,5-trisphosphate (IP₃) receptors with 2-aminoethoxydiphenylborate (10^–4 mol·l^–1). Both blockers also inhibited the NH₂Cl-induced increase in I_sc. These results indicate that an intracellular Ca²⁺ release via ryanodine and/or IP₃ receptors is involved in oxidant stimulation of anion secretion in rat colon.     

Essential tremor, nystagmus and duodenal ulceration. A "new" dominantly inherited condition.

The familial occurrence of essential tremor combined with (congenital) nystagmus, duodenal ulceration and a narcolepsy-like sleep disturbance caused by an autosomal dominant gene with high penetrance and fairly uniform expressivity is reported in a family of Swedish-Finnish ancestry. Twelve of 17 affected family members had essential tremor which began between 30-40 years of age and which could be controlled temporarily by alcohol; this resulted in alcoholism in several affected individuals. The most severly affected persons showed cerebellar signs which may reflect a possible pathogenetic relationship of the syndrome to the genetic cerebellar atrophies. Nystagmus, observed in 12 of 17 affected family members (eight of whom were also affected with tremor) usually was congenital and accompanied by refractive errors. Duodenal ulcers occurred almost exclusively in individuals with the neurological syndrome, and preceded its onset in some cases. The ulcer disease therefore seems to be a component manifestation of the syndrome and is interpreted as a pleiotropic effect of the gene which also causes the nystagmus, tremor and sleep disturbance.     

Detection of methicillin-resistant Staphylococcus aureus and simultaneous confirmation by automated nucleic acid extraction and real-time PCR

A molecular assay for the simultaneous detection of a Staphylococcus aureus-specific gene and the mecA gene, responsible for the resistance to methicillin in staphylococci, was evaluated. The assay included an automated DNA extraction protocol conducted with a MagNA Pure instrument and real-time PCR conducted with a LightCycler instrument. The performance and robustness of the assay were evaluated for a suspension of methicillin-resistant S. aureus (MRSA) strain with a turbidity equivalent to a McFarland standard of 0.5, which was found to be the ideal working concentration. The specificity of the new molecular assay was tested with a panel of 30 gram-negative and gram-positive bacterial strains other than MRSA. No cross-reactivity was observed. In a clinical study, 109 isolates of MRSA were investigated. All clinical MRSA isolates gave positive results for the S. aureus-specific genomic target, and all but one were positive for the mecA gene. In conclusion, the new molecular assay was found to be quick, robust, and laborsaving, and it proved to be suitable for a routine molecular diagnostic laboratory.     

Langmuir-Blodgett films of photochromic polyglutamates, 10. The influence of the side chain architecture on the thermal and monolayer forming properties of “hairy rod”-like polymers

The phase behavior of so called “hairy rod”-like polymers with mesogenic elements in the side chains was investigated by means of differential scanning calorimetry and X-ray diffraction and correlated with the properties of their monolayers at the air/water interface. The side chains of the polymers form a highly ordered (crystalline?) structure. The degree of crystallinity and the temperature of the phase transition to a less ordered liquid crystalline structure depend strongly on the side chain architecture. A higher degree of crystallinity is found for a decyloxy tail group than for a hexyl tail group, since alkoxy groups at the mesogenic elements can be packed more tightly. X-ray diffraction proves that the side chains with a hexyl tail form a liquid crystalline phase, which may provide a fluid matrix for the rigid rod like backbones. The monolayers of these polymers with the side chains in a liquid crystalline phase at room temperature consist of soft domains and can be transferred to homogeneous Langmuir-Blodgett films. By way of contrast the polymers in which the side chains are in a more highly ordered (crystalline) phase form stiff domains in the monolayers, resulting in isotherms with a shallow increase in surface pressure. Furthermore, a strong temperature dependence is found for the isotherms which can be interpreted to be a result of domain softening. The monolayers of the polymers with highly ordered side chains can be transferred only after inducing some disorder either photochemically or by increasing the temperature.     

Polyimides with cyclohexyl-substituted indan groups in the main chain

A diamine monomer containing the 1,3-biscyclohexyl-1-methylindan group was prepared, starting from cyclohexyl phenyl ketone in four steps. This monomer was reacted with six different dianhydrides (pyromellitic dianhydride, 3,4:3′,4′-biphenyltetracarboxylic dianhydride, 3,4:3′,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, 4,4′-sulfonyldiphthalic anhydride, 4,4′-perfluoroisopropylidenediphthalic anhydride) to give the corresponding polyimides via the poly(amic acid) precursors and thermal imidization. All of these polyimides were soluble at least in N-methyl-2-pyrrolidone (NMP) at elevated temperatures, some were soluble in NMP and chlorinated hydrocarbons even at room temperature. The polymers were characterized by nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and dynamic thermogravimetry. All polyimides proved to be amorphous with glass transition temperatures in the range between 261°C and 295°C depending on the nature of the dianhydride moiety. Their decomposition proceeds in two steps, starting at 400°C probably with loss of the cyclohexyl substituents.     

Identification of wild-type and mutant p53 peptides binding to HLA-A2 assessed by a peptide loading-deficient cell line assay and a novel major histocompatibility complex class I peptide binding assay

Mutations of the p53 gene are the most frequently observed genetic changes in human cancers; often leading to an overexpression of the wild-type (wt) p53 protein. Demonstrable T cell reactivity against tumor cells overexpressing wt or mutant p53-derived peptides could support the application of such epitopes in cancer immunotherapies. As the binding of peptide to MHC class I molecules is a prerequisite for antigen-specific T cell recognition, we evaluated the ability of wt and mutant p53 peptides to bind to HLA-A2.1 using two independent flow cytometry-based assay systems, the T2 major histocompatibility complex (MHC) class I peptide stabilization assay (stabilization assay) and the peptide-induced MHC class I reconstitution assay (reconstitution assay). The twenty selected wt sequences each conformed to the previously reported HLA-A2.1 peptide binding motif. Seven of the wt p53 and 2/13 mutant p53 peptides derived from the previously chosen wt peptides bound to HLA-A2.1 in both the stabilization and the reconstitution assays. An additional six wt and six mutant p53 peptides, presumably exhibiting lower affinity for HLA-A2.1, were identified only in the reconstitution assay. Those p53 peptides binding HLA-A2.1 may provide useful immunogens for the generation of HLA-A2.1-restricted cytolytic T lymphocytes in vitro and in vivo.     

REACTIVITY OF LYMPHOCYTE SUBPOPULATIONS IN HUMAN MIXED LYMPHOCYTE CULTURE

Loss of antigenicity in the mixed lymphocyte culture (MLC) reaction of lymphocytes precultured at 22°C for 7–10 days was accompanied by a decrease in bone-marrow-derived lymphocytes (B cells) from 22 ± 1% to 13 ± 1%, and an increase in thymus-derived lymphocytes (T cells) from 65 ± 2% to 83 ± 1% (P < 0.001). Depletion of B cells from a fresh lymphocyte suspension by either antihuman immunoglobulin-coated column fractionation or by sheep red blood cell (SRBC) rosette formation resulted in a significant reduction of the cell's ability to stimulate in MLC (P < 0.001). Coating of lymphocytes with rabbit antihuman brain serum abrogated their ability to respond but not the ability to stimulate in MLC.     

Poly(2,5-dialkoxy-p-phenylene)s—synthesis and properties

The synthesis of poly(2,5-dialkoxy-p-phenylene)s (PPP) by palladium-catalyzed polycondensation of 2,5-dialkoxy-4-bromophenylboronic acids is described. Number-average degrees of polymerization of ca. 30 have been reached at best. The characterization of the polymers by NMR, IR, UV-VIS and fluorescence spectra, data on the bulk structure obtained by X-ray methods, melting behavior and thermal stability are reported. PPP's with long alkoxy side chains exhibit a layered phase structure, those with short or branched alkoxy side chains, cylindrical packing. Poly(2,5-dibutoxy-p-phenylene) was prepared with chain lengths 7 ≤ P_n ≤ 30. The polymer with P_n of 30 shows thermal transitions in the bulk phase at 182°C and 227°C. It forms an anisotropic melt above 227°C which only starts decomposing if heated above 300°C. The polymers of shorter chain length show isotropic melts, with the melting point strongly depending on chain length.