Role of Surface-Anchored Polymer Chains in Adhesion and Slippage

When in contact with an attractive wall, polymer chains tend to form thick, surface-anchored layers with an internal structure which can be controlled. We present and analyze experiments conducted on model systems aimed at understanding how such surface-anchored polymer layers can act as adhesion promoters or can induce wall slip. For both situations, the key parameter is the degree of interdigitation between the surface layer and the bulk polymer system, either an elastomer or a melt. We analyze how this degree of interdigitation governs the optimum enhancement in the adhesion energy between the solid wall and an elastomer, and how it is at the origin of the very different wall slip regimes observed experimentally.     

Growth arrest failure, G1 restriction point override, and S phase death of sensory precursor cells in the absence of neurotrophin-3

The attachment of pathogenic microorganisms to host cells and tissues is often mediated through the expression of surface receptors recognizing components of the extracellular matrix (ECM). Here, we investigate the ability of Borrelia spirochaetes to bind the ECM constituent, fibronectin. Borrelia lysates were separated by SDS-PAGE, transferred to nitrocellulose and probed with alkaline phosphatase-labelled fibronectin (fibronectin-AP). Five of six Borrelia species and four of eight B. burgdorferi sensu lato isolates expressed one or more fibronectin-binding proteins. Borrelia burgdorferi isolate B31 expressed a 47 kDa (P47) fibronectin-binding protein that was localized to the outer envelope based on susceptibility to proteinase K. The interaction of P47 with fibronectin was specific, and the region of fibronectin bound by P47 mapped to the gelatin/collagen binding domain. P47 was purified by affinity chromatography, digested with endoproteinase Lys-C, and the peptide fragments analysed by liquid chromatography/tandem mass spectroscopy. A search of protein databases disclosed that the P47 peptide mass profile matched that predicted for the bbk32 gene product of B. burgdorferi isolate B31. The bbk32 gene was cloned into Escherichia coli, and the ability of recombinant BBK32 to bind fibronectin and inhibit the attachment of B. burgdorferi was demonstrated. The identification of BBK32 as a receptor for fibronectin binding may enhance our understanding of the pathogenesis and chronic nature of Lyme disease.     

Oral hygiene in relation to caries development and immigrant status in infants and toddlers

The purpose of this study was to describe oral hygiene factors in infants and toddlers living in Sweden with special reference to caries prevalence at 2 and 3 yr of age and to immigrant status. The study was designed as a prospective, longitudinal study starting with 671 children aged 1 yr. At 3 yr, all the children were invited to a further examination. A total of 298 children, randomly selected from the original group, were also examined at 2 yr. The accompanying parent was interviewed about the child's oral health habits. Children who were free of caries at 3 yr had had their teeth brushed more frequently at 1 and 2 yr of age, had used fluoride (F)-toothpaste more often at 2 yr of age, and had a lower prevalence of visible plaque at 1 and 2 yr of age than children with caries. Immigrant children had had their teeth brushed less frequently, had used less F-toothpaste, and had a higher prevalence of visible plaque at 1 yr of age than nonimmigrant children. Early establishment of good oral hygiene habits and regular use of F-toothpaste seem to be important for achieving good oral health in pre-schoolchildren.     

In vitro activity of lumefantrine (benflumetol) against clinical isolates of Plasmodium falciparum in Yaoundé, Cameroon

The in vitro antimalarial activity of the new Chinese synthetic drug, lumefantrine, also known as benflumetol (a fluorene derivative belonging to the aminoalcohol class), was determined by an isotopic microtest against 61 fresh clinical isolates of Plasmodium falciparum and compared with that of other established antimalarial agents. The geometric mean 50% inhibitory concentration of lumefantrine was 11.9 nmol/liter (95% confidence intervals, 10.4 to 13.6 nmol/liter; range, 3.3 to 25.6 nmol/liter). The in vitro activities of lumefantrine against the chloroquine-sensitive and the chloroquine-resistant isolates did not differ (P > 0.05). There was a significant positive correlation of responses between lumefantrine and two other aminoalcohols studied, mefloquine (r = 0.688) and halofantrine (r = 0.677), and between lumefantrine and artesunate (r = 0.420), suggesting a potential for in vitro cross-resistance. Our data suggest high in vitro activity of lumefantrine, comparable to that of mefloquine, and are in agreement with the promising results of preliminary clinical trials.     

Hyaluronan in human cerebrospinal fluid

We studied the concentration of hyaluronan in cerebrospinal fluid (CSF) in various diseases and attempted to define its reference interval. A radioassay utilizing cartilage proteins with affinity for hyaluronan was used in determining the concentration of 200 lumbar and 27 ventricular CSF specimens and 11 brain cyst fluids. Molecular weight distributions were determined by gel chromatography and localization in brain tissue by histochemistry. The hyaluronan level of lumbar CSF showed an increase with age; comparatively healthy children had (mean +/- SD) 50 +/- 41 micrograms/L (n = 40) and adults 166 +/- 77 micrograms/L (n = 9); i.e. significantly different values. The highest level was recorded in a patient with meningitis (> 8000 micrograms/L). More than 4000 micrograms/ L was noted in a patient with tumour metastasis in the cerebellum. Significantly elevated levels were especially found with spinal stenosis, head injury and cerebral infarction, but also in inflammatory medical disorders, hydrocephalus and encephalitis. We found no significant increase in multiple sclerosis and some other neurological diseases. Ventricular CSF of adults contained significantly less hyaluronan (53 +/- 73 micrograms/L; n = 16) than lumbar CSF. Hyaluronan in cyst fluids varied from 31 to 25,000 micrograms/L. Weight average molecular weight of hyaluronan in CSF was 2.9-3.0 x 10(5) and in brain tumour cyst fluid 2.4 x 10(6). In search for the origin of hyaluronan in CSF it was found that its concentration in the choroid plexus and leptomeninges was low, but that hyaluronan was accumulated in the superficial layer of the cerebral cortex. Continued screening for hyaluronan in CSF may be valuable in cases of inflammatory diseases, tumours and obstruction to CSF flow.     

Morphology of the lymphoid tissue of the bronchus in healthy persons of various ages, and the effect of smoking

The results of 315 endonasal operations on the lacrimal duct with long intubation are analyzed. The most incident complication of long intubation of the lacrimal duct is formation of intubation granulomas, which are most often localized in the inferior lacrimal canaliculus; their etiology is sometimes allergic--they form as a response of adjacent tissues to the material of the intubation tube, and the findings of our recent histological study prove it. The diagnosis of intubation granulomas is easy in the majority of cases. The treatment consists in removal and obligatory adequate total and local antiallergic therapy decelerating the growth and relapses of granulomas. After removal of the intubation tube the growth of granulations ceases and a fine cicatrix forms.     

Disruption of cellular translational control by a viral truncated eukaryotic translation initiation factor 2alpha kinase homolog

Phosphorylation of eukaryotic translation initiation factor 2alpha (eIF2alpha) is a common cellular mechanism to limit protein synthesis in stress conditions. Baculovirus PK2, which resembles the C-terminal half of a protein kinase domain, was found to inhibit both human and yeast eIF2alpha kinases. Insect cells infected with wild-type, but not pk2-deleted, baculovirus exhibited reduced eIF2alpha phosphorylation and increased translational activity. The negative regulatory effect of human protein kinase RNA-regulated (PKR), an eIF2alpha kinase, on virus production was counteracted by PK2, indicating that baculoviruses have evolved a unique strategy for disrupting a host stress response. PK2 was found in complex with PKR and blocked kinase autophosphorylation in vivo, suggesting a mechanism of kinase inhibition mediated by interaction between truncated and intact kinase domains.     

Heparin removal after cardiopulmonary bypass in a patient with adverse reaction to protamine

A 74-year-old man underwent elective coronary surgery under cardiopulmonary bypass. A few minutes after the protamine administration was started, he suddenly developed a severe hypotension necessitating cardiac massage and recannulation for pump assistance. A further test dose of protamine provoked an identical reaction. We installed a Heparin Removal Device, which allows for ex-vivo deheparinization. In 35 minutes ACT decreased from 480 sec to 180 sec and clots appeared in the operating field. This system provides an excellent alternative to protamine in patients with an adverse reaction to protamine.