Diamond-Like Carbon: A Surface for Extreme, High-Wear Environments

In this study, we present an in-depth characterization of a diamond-like carbon (DLC) film, using a range of techniques to understand the structure and chemistry of the film both in the interior and particularly at the DLC/air surface and DLC/liquid interface. The DLC film is found to be a combination of sp2 and sp3 carbon, with significant oxygen present at the surface. The oxygen seems to be present as OH groups, making the DLC somewhat hydrophilic. Quartz-Crystal Microbalance (QCM) isotherms and complementary neutron reflectivity data indicate significant adsorption of a model additive, bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) surfactant, onto the DLC from water solutions and indicate the adsorbed film is a bilayer. This initial study of the structure and composition of a model surfactant is intended to give a clearer insight into how DLC and additives function as antiwear systems.

Opinions of children about participation in medical genetic research

AIMS

The objective was to evaluate children's opinions about their participation in a large research project.

METHODS

Polish children between 6 and 14 years of age completed a questionnaire about their participation in the Polish Gabriel study (which aims to identify genetic and environmental causes of asthma). In total 706 questionnaires were collected.

RESULTS

Children's main motivation for participation was wanting to know whether they were healthy or not. Most children could think of no reasons to reconsider participation. Children aged 6-10 years might reconsider participating because they did not know what was going to happen. A third of the children were not informed by anybody about the study. Especially the youngest children indicated a need for a tailored letter (42%). The youngest children were less often asked for their opinion about participation. All children preferred that both parents and children are asked for consent or assent. Children who were not informed or not asked for their opinion seemed less emotionally involved in the study.

CONCLUSION

While researchers and parents tend to focus their information provision to older children and include them in decision-making, especially the younger children expressed a need for more tailored information and involvement in their participation in research.

The use of lamotrigine, vigabatrin and gabapentin as add-on therapy in intractable epilepsy of childhood

PURPOSE

Lamotrigine (LTG), vigabatrin (VGB) and gabapentin (GBP) are three anti-epileptic drugs (AEDs) used in the treatment of children with epilepsy for which long-term retention rates are not currently well known. This study examines the efficacy, long-term survival and adverse event profile of these three agents used as add-on therapy in children with refractory epilepsy over a 10-year period.

METHODS

Three separate audits were conducted between February 1996 and September 2000. All children studied had epilepsy refractory to other AEDs. Efficacy was confirmed if a patient became seizure free or achieved >50% reduction in seizure frequency for 6 months or more after starting therapy. Adverse events and patient survival for each drug were recorded at the end of the study period.

RESULTS

Between September 1990 and February 1996, 132 children received LTG, 80 VGB and 39 GBP. At the 10-year follow-up audit, 33% of the children on LTG had a sustained beneficial effect on their seizure frequency in contrast to 19% for VGB and 15% for GBP. No significant difference in efficacy was found in children with partial seizures. Children with epileptic encephalopathy (EE) including myoclonic-astatic epilepsy and Lennox-Gastaut Syndrome (LGS) achieved a more favorable response to LTG. The main reasons for drug withdrawal were lack of efficacy for VGB, apparent worsening of seizures for GBP and the development of a rash for LTG.

CONCLUSIONS

Lamotrigine is a useful add-on therapy in treating children with epilepsy. It has a low adverse event profile and a sustained beneficial effect in children with intractable epilepsy.

Dynamics of the COPII coat with GTP and stable analogues

We have developed an assay to monitor the assembly of the COPII coat onto liposomes in real time. We show that with Sar1pGTP bound to liposomes, a single round of assembly and disassembly of the COPII coat lasts a few seconds. The two large COPII complexes Sec23/24p and Sec13/31p bind almost instantaneously (in less than 1 s) to Sar1pGTP-doped liposomes. This binding is followed by a fast (less than 10 s) disassembly due to a 10-fold acceleration of the GTPase-activating protein activity of Sec23/24p by the Sec13/31p complex. Experiments with the phosphate analogue BeFx suggest that Sec23/24p provides residues directly involved in GTP hydrolysis on Sar1p.

First record and morphology of Myialges caulotoon (Acari: Epidermoptidae) from Galapagos hosts

Hippoboscid flies were collected from wild birds on Santiago and Fernandina Islands, Galapagos, Ecuador in August 1985. An epidermoptid mite, identified as Myialges caulotoon, was found on Icosta nigra from Galapagos Hawks and on Olfersia sordida from Brown Pelicans and a Flightless Cormorant. This report is the first record of Myialges from the 2 birds endemic to Galapagos. It is also the first report to provide an identity of a species of Myialges from Galapagos hosts.

Low altitude dose measurements from APEX, CRRES and DMSP

Dosimeter data taken on the APEX (1994-1996), CRRES (1990-1991) and DMSP (1984-1987) satellites have been used to study the low altitude (down to 350 km) radiation environment. Of special concern has been the inner edge of the inner radiation belt due to its steep gradient. We have constructed dose models of the inner edge of the belt from all three spacecraft and put them into a personal computer utility, called APEXRAD, that calculates dose for user-selected orbits. The variation of dose for low altitude, circular orbits is given as a function of altitude, inclination and particle type. Dose-depth curves show that shielding greater than approximately 1/4 in Al is largely ineffectual for low altitude orbits. The contribution of outer zone electrons to low altitude dose is shown to be important only for thin shields and to have significant variation with magnetic activity and solar cycle.

Identification of amino acids within the MHC molecule important for the interaction with the adenovirus protein E3/19K

The E3/19K protein of human adenovirus type 2 binds to class I MHC Ags thereby interfering with their cell surface expression and Ag presentation function. Currently, it is unclear exactly which structure of MHC molecules is recognized by the E3/19K protein. We have previously demonstrated that the murine H-2Kd Ag is able to associate with E3/19K, whereas the allelic H-2Kk molecule is not. By using exon shuffling between Kd and Kk molecules, the alpha 1 and alpha 2 domains of MHC class I molecules were identified as essential structures for binding the viral protein. In this report, we have examined the contribution of individual amino acids within the alpha 2 domain of MHC for binding E3/19K. First, we show that within this domain the alpha-helical part is most important for the interaction with E3/19K. By using site-directed mutagenesis, Kd-specific amino acids were introduced into the alpha-helix of the alpha 2 domain of Kk. By using the expression of mutagenized proteins in E3/19K+ cells, we have identified Tyr 156 and Leu 180 as being essential for the association with the E3/19K protein. In addition, Kd residue Glu 163 seems to contribute to the complex formation. Furthermore, analysis of a panel of Kd/Dd recombinants indicates that a similar region in the Dd molecule, namely, the C-terminal half of the alpha 2 domain, affects binding to E3/19K. Combining these results with Ab binding data, we present two alternative models of how the adenovirus protein may bind to the alpha 1 and alpha 2 domains.

Identification of amino acids within the MHC molecule important for the interaction with the adenovirus protein E3/19K

The E3/19K protein of human adenovirus type 2 binds to class I MHC Ags thereby interfering with their cell surface expression and Ag presentation function. Currently, it is unclear exactly which structure of MHC molecules is recognized by the E3/19K protein. We have previously demonstrated that the murine H-2Kd Ag is able to associate with E3/19K, whereas the allelic H-2Kk molecule is not. By using exon shuffling between Kd and Kk molecules, the alpha 1 and alpha 2 domains of MHC class I molecules were identified as essential structures for binding the viral protein. In this report, we have examined the contribution of individual amino acids within the alpha 2 domain of MHC for binding E3/19K. First, we show that within this domain the alpha-helical part is most important for the interaction with E3/19K. By using site-directed mutagenesis, Kd-specific amino acids were introduced into the alpha-helix of the alpha 2 domain of Kk. By using the expression of mutagenized proteins in E3/19K+ cells, we have identified Tyr 156 and Leu 180 as being essential for the association with the E3/19K protein. In addition, Kd residue Glu 163 seems to contribute to the complex formation. Furthermore, analysis of a panel of Kd/Dd recombinants indicates that a similar region in the Dd molecule, namely, the C-terminal half of the alpha 2 domain, affects binding to E3/19K. Combining these results with Ab binding data, we present two alternative models of how the adenovirus protein may bind to the alpha 1 and alpha 2 domains.

Genetic typing using automated electrophoresis and fluorescence detection

Multi-color fluorescence detection systems offer unique advantages when compared to single label detection methods for DNA typing, genetic disease testing, population fingerprinting, and DNA mapping. Internal controls are easily used and identified by different color dye labels. Multiple independent samples or multiple analyses of the same sample are run in each lane of a gel. Precision of size assignment and quantification are improved. Here, we will review a variety of methods used to analyze DNA and present the advantages of the multi-color fluorescence dye approach. An automated and quantitative DNA typing assay for human identification is shown. This method is an improvement over previous manual techniques and uses multi-color fluorescence labeling, electrophoresis and real-time detection methodology.

Tropical spastic paraparesis: clinical, immunological, and virological studies in two patients from Martinique

Two patients from Martinique with tropical spastic paraparesis had antibodies to human T-lymphotropic virus type I (HTLV-I) in serum and spinal fluid but no antibodies to other retroviruses tested. They presented with spastic weakness of both lower extremities, hyperreflexia with upgoing toes, sphincteric dysfunction, and normal sensation. By means of agarose isoelectric focusing and selective immunoblotting we demonstrated an increased intrathecal synthesis of IgG antibodies to HTLV-I in the spinal fluid. Unique oligoclonal bands of IgG antibodies to HTLV-I were present in the cerebrospinal fluid. Using a battery of monoclonal antibodies we also found in these patients an increased number of circulating T cells that expressed activation markers. We conclude that the HTLV-I retrovirus associated with tropical spastic paraparesis has both lymphocytotropic and neurotropic properties.

Effect of atrial natriuretic factor on acid-base homeostasis

Both micropuncture and clearance studies have shown that the anion excreted in the urine in response to the increased glomerular filtration rate and solute load induced by atrial natriuretic factor (ANF) depends on the pre-existing acid-base status. In normal animals, the kidney is relatively better at reabsorbing bicarbonate than chloride, as ANF increases luminal flow so that a chloruresis without bicarbonaturia ensues. In contrast, during chronic hypochloraemic metabolic alkalosis, alkalaemia renders the kidney unable to reabsorb the increment in filtered bicarbonate induced by ANF so that bicarbonaturia occurs with amelioration of the alkalosis. Since the relative magnitudes of chloride versus bicarbonate excretion rates in response to ANF are a function of the plasma anion concentrations, ANF tends to correct acid-base disorders.

Virus antibodies in the cerebrospinal fluid of multiple sclerosis patients detected with ELISA tests

The enzyme-linked immunosorbent assay (ELISA) was used to determine levels of specific IgG antibodies against measles, rubella, vaccinia, corona (OC43) and mumps viruses in cerebrospinal fluid (CSF) and serum of 18 patients with clinically definite multiple sclerosis (MS), 8 patients with optic neuritis (ON), 27 patients with other neurological disease (OND), and 88 control subjects without central nervous system disease. Serum antibody levels were not significantly different between the four groups. Differences in the frequency and levels of CSF antibodies between the four groups were observed. Control patients had serum/CSF antibody ratios from 2.0 to 3.0 (log) with an average of 2.5 corresponding to a 320-fold difference between serum and CSF antibody levels. MS patients had ratios from 1.1 to 2.1 with an average of 1.6. The average was 2.0 for the ON patients. The average for the OND patients was similar to the controls. The altered serum/CSF ratios for several viruses within an individual patient was similar. These results suggest that nonspecific immunostimulation is responsible for the increased levels of CSF virus antibodies.

Serological Investigation of the possibility of congenital transmission of papovavirus JC

In an examination of paired sera from pregnant women, 9 of 57 women who had JC virus antibodies in their first specimens exhibited virus reactivation, as judged by a fourfold or greater rise in JC virus hemagglutination-inhibiting antibodies; 43 women remained seronegative through pregnancy. JC virus-specific immunoglobulin M was not demonstrated in umbilical cord sera of six infants born to mothers showing reactivation or in 300 additional umbilical cord sera from normal pregnancies.

Comparison of hemagglutination inhibition test and enzyme-linked immunosorbent assay for determining antibody to rubella virus

The hemagglutination inhibition test (HAI) and the enzyme-linked immunosorbent assay (ELISA) for detecting antibody to rubella virus were compared by testing 25 sets of paired sera taken before and after infection and 10 sets of sera taken during acute and convalescent stages of the disease and by screening 700 serum samples from the Collaborative Perinatal Project, NIH/NINCDS. The tests were found to be comparable in their ability to detect positive and negative sera, rises in titers, and seroconversions. When a purified antigen and carefully prepared reagents were used, ELISA was found to be as accurate and reliable as HAI. ELISA required no pretreatment of serum, could easily be automated, and was less time-consuming than HAI.

CSF oligoclonal bands, immunoglobulins, and viral antibodies in progressive myoclonus epilepsy

We studied CSF and serum samples from 16 patients with progressive myoclonus epilepsy (PME). These patients had juvenile-onset PME with evidence of autosomal recessive inheritance and no Lafora bodies. Twelve of the 16 patients with PME had immunologic abnormalities. Oligoclonal gamma bands were seen in six of the eight patients from whom sufficient CSF was available. The CSF albumin and serum/CSF albumin ratios were normal in all 16 patients, indicating the presence of intact blood-brain barriers. Six of the 16 patients showed increased CSF IgG levels and five had an increased CNS IgG synthesis. All patients had normal serum and CSF IgM and IgA levels. Three patients, all with bands, had reduced measles and/or vaccinia serum/CSF antibody ratios. The findings suggest altered immune response of the CNS of some patients with PME apparently caused by nonspecific immunostimulation.

Serological investigation of BK papovavirus infection in pregnant women and their offspring

Paired sera from 150 pregnant women and 387 umbilical cord sera were tested for BK virus (BKV) antibodies. The hemagglutination inhibition, neutralization, and indirect immunofluorescence tests were employed for the detection of antibodies. Treatment of serum with anti-gamma Fc and tests of immunoglobulin M (IgM) fractions for antibodies were utilized as required to detect and validate the presence of virus-specific IgM. The BKV antibody prevalence in the sera collected at the time of the first prenatal visit was 75% by hemagglutination inhibition and 91% by neutralization tests. A total of 95% of the women had antibodies by at least one of the three serological tests. Five of 100 women with normal pregnancies exhibited BKV activity during pregnancy as evidenced by a greater than fourfold rise in BKV hemagglutination inhibition antibody titers and acquisition of BKV-specific IgM. The antibody rise occurred in the younger women and appeared to be a result of reactivation of the virus rather than of primary infection. Two instances of possible recent BKV infections were identified. BKV-specific IgM was not detected in any of the 387 umbilical cord sera which included three specimens from infants born to mothers with definite or probable BKV activity during pregnancy and 50 specimens with IgM levels of > 20 mg/100 ml. The results indicate that few women in the child-bearing age are nonimmune to BKV and that, although reactivation of infection occurs in pregnancy, congenital transmission of the virus either does not occur or is rare.

Swine influenza virus vaccination in patients with multiple sclerosis

A double-blind, placebo-controlled study was conducted to evaluate the safety and efficacy of inactivated influenza virus vaccines in patients with multiple sclerosis. The vaccine used contained 200 chick cell-agglutinating (CCA) units of influenza A/New Jersey/76 and 200 CCA units of influenza A/Victoria/75 whole viruses (Merrell-National Laboratories, Cincinnati, Ohio). The frequency of clinical relapses of multiple sclerosis was the same in the vaccine-treated (four of 33 patients) and placebo-treated (four of 33) groups. An untreated control group had a slightly higher rate of relapses (four of 22). Toxic reactions to the vaccine were not a significant problem. The efficacy of the vaccination as measured by titers of hemagglutination-inhibiting antibody was comparable to that reported for the general population. However, patients with preexisting antibody were less responsive to the vaccine than normal controls studied previously. The patients who did not respond to the vaccine tended to be older and more disabled. There were no changes in titers of antibody to rubeola or rubella virus after vaccination or in relation to change in clinical course. It is concluded that the vaccine is safe and effective in patients with multiple sclerosis.