Structural characterisation of Na2ZrO3

A combination of X-ray and electron diffraction, electron microscopy and solid-state nuclear magnetic resonance (NMR) has been used to elucidate the structure and the ordering of Na2ZrO3. The diffraction data confirm a monoclinic crystal structure. A sample prepared by a conventional solid-state reaction of the components is shown by both X-ray diffraction and electron microscope imaging to have an extremely high concentration of planar defects associated with stacking disorder of the planes along the c-axis. The incidence of these defects is significantly reduced in a sample recrystallised from a bismuth oxide flux. NMR indicates that the local coordinations are well defined in both samples but with some sharpening of the spectra from the recrystallised sample indicative of the increase of long-range order. The 23Na magic angle spinning (MAS) NMR spectra clearly show three distinct sites with widely differing quadrupolar interaction parameters that can be related to the known site symmetries. Two distinct oxygen resonances are observed in the MAS NMR spectrum from an 17O-enriched sample while the static 91Zr NMR spectrum can be simulated with one set of interaction parameters.

29Si and 27Al magic-angle spinning nuclear magnetic resonance of sialon X-phase

The 29Si isotropic chemical shift of sialon X-phase (Si3Al6O12N2) is reported unequivocally for the first time. The implications of the 29Si and 27Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra for atomic ordering within X-phase are discussed.

Time series for modelling counts from a relapsing-remitting disease: application to modelling disease activity in multiple sclerosis

Many chronic diseases are relapsing-remitting diseases, in which subjects alternate between periods with increasing and decreasing disease activity; relapsing-remitting multiple sclerosis is an example. This paper proposes two classes of models for sequences of counts observed from a relapsing-remitting disease. In the first, the relapsing-remitting nature of the data is modelled by a Poisson time series with a periodic trend in the mean. In this approach, the mean is expressed as a function of a sinusoidal trend and past observations of the time series. An algorithm that uses GLIM is developed, and it results in maximum-likelihood estimation for the amplitude, frequency and autoregressive effects. In the second class of models, the relapsing-remitting behaviour is described by a Poisson time series in which changes in the mean follow a latent Markov chain. An EM algorithm is developed for maximum-likelihood estimation for this model. The two models are illustrated and compared with data from a study evaluating the use of serial magnetic resonance imaging as a measure of disease activity in relapsing-remitting multiple sclerosis.

A whole-person sampler for assessing numbers of host-seeking adult mosquitoes

The whole-person bag sampler (WPBS) is a human-baited drop-net mosquito trap for evaluating an individual's exposure to nuisance mosquitoes. A diagram of WPBS construction is given, with results from field tests. Trap operator exposures of 2, 4, and 8 min did not result in a corresponding increase in mosquitoes caught in the WPBS, although simultaneous captures using a sweep net or Nasci aspirator increased with the sample duration. The person baiting and operating the trap did not have a significant effect on number of mosquitoes captured. Taxonomic diversity of adult mosquitoes collected with WPBS and CO2-baited traps was similar, with Aedes vexans predominant in the study areas.

ACTH (4-10) increases quantal content at the mouse neuromuscular junction

Adrenocorticotropic hormone 4-10 (ACTH 4-10), in concentrations of 50 nM and 1 microM, increased both the frequency of miniature endplate potentials and the amplitude of the endplate potentials in addition to decreasing the number of failures following stimulation of the phrenic nerve in the mouse in vitro. There was no effect of the peptide on either the amplitude of the miniature endplate potentials or the resting membrane potential of the muscle fibres. These results indicate that the action of ACTH 4-10 was to increase the quantal content of the endplate potential via a presynaptic action.

Serial contrast-enhanced magnetic resonance imaging in patients with early relapsing-remitting multiple sclerosis: implications for treatment trials

Serial monthly contrast-enhanced MRIs were performed in 10 early relapsing-remitting patients with multiple sclerosis and 2 patients with chronic progressive disease for a period of 12 to 55 months. MRI was performed at 1.5 T using contiguous 5-mm slices with pre- and postgadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) T1-weighted and T2-weighted images. New and total number of Gd-DTPA-enhancing lesions were numbered and counted and lesion areas were correlated to an increase of > or = 0.5 in Expanded Disability Status Scale (EDSS) scores. The frequency of enhancing lesions varied from patient to patient; however, there was a correlation between a burst of enhancing lesion number and area above the individual's mean lesion frequency to an increase in EDSS score. A bootstrap analysis of the lesion count was performed to develop a statistical basis for determining population sizes for treatment trials. These results provide a basis for the potential use of contrast-enhanced MRI as a primary outcome measure in phase II treatment trials involving patients with relapsing-remitting MS.

Upregulation of the pro-opiomelanocortin gene in spinal motoneurones in muscular dystrophy in mice

Pro-opiomelanocortin (POMC) mRNA was detected in motoneurones of mice using histochemical in situ hybridization and cDNA oligonucleotide probes for the adrenocorticotropin (ACTH) 4-11 and beta-endorphin 1-8 regions of POMC. Staining for POMC mRNA was negligible in motoneurones in normal adult mice but in dystrophic mice the mRNA was present in > 60% of the ventral horn cells. It is concluded that neuropathic change in motoneurones is accompanied by upregulation of the POMC gene and synthesis of POMC-derived peptides.

Involvement of cytochromes in the anaerobic biotransformation of tetrachloromethane by Shewanella putrefaciens 200

Shewanella putrefaciens 200 is an obligate respiratory bacterium that can utilize a variety of terminal electron acceptors, e.g., NO3-, NO2-, Fe(III), and trimethylamine N-oxide, in the absence of O2. The bacterium catalyzed the reductive transformation of tetrachloromethane (CT) under anaerobic conditions. The only identified product was trichloromethane (CF), but CF production was not stoichiometric. No dichloromethane, chloromethane, or methane was produced. A chloride mass balance indicated that fully dechlorinated products were not formed. Studies with [14C]CT suggested that a portion of the transformed CT reacted with biomass to form unidentified soluble and insoluble products. Intermediate production of a trichloromethyl radical can explain observed product distribution without significant CO2 formation. Evidence suggests that respiratory c-type cytochromes are responsible for the dehalogenation ability of S. putrefaciens 200. Previous growth under microaerobic conditions ([O2], < 2.5 microM) results in (i) a 2.6-fold increase in specific heme c content and (ii) a 2.3-fold increase in specific rates of anaerobic CT transformation. Manipulation of heme content by growth on iron-free medium or medium amended with delta-aminolevulinic acid showed that CT transformation rates increase with increases in specific heme c content. Transformation of CT is inhibited by CO. Dehalogenation studies with periplasmic, cytoplasmic, and membrane fractions indicated that only periplasmic and membrane fractions possessed dehalogenation ability. Cytochromes c were the predominant cytochromes present. Membranes were also found to contain smaller amounts of cytochrome b. Observed CT transformation patterns are consistent with a cometabolic description involving fortuitous CT reduction by reduced c-type cytochromes.

ENOD8, a novel early nodule-specific gene, is expressed in empty alfalfa nodules

The alfalfa ENOD8 nodule-specific gene is expressed in empty nodules elicited by exopolysaccharide-deficient Rhizobium meliloti, and it is expressed early in nodule development. An ENOD8 cDNA was sequenced and found to encode a novel product. Its deduced polypeptide sequence was found to be similar to the nonproline-rich domains of the putative polypeptides encoded by a class of anther-specific genes from Arabidopsis thaliana and Brassica napus. The role of the ENOD8 gene product is predicted to be in nodule organogenesis. ENOD8 is expressed in a developmental pathway triggered as a result of Rhizobium nodulation signal transduction.

Absorption and disposition of a new antiarrhythmic agent bidisomide in man

Absorption and disposition of bidisomide were studied in 12 healthy male subjects after a 20-min iv (1 mg/kg; N = 6) infusion and oral (2 mg/kg; N = 6) administration of the 14C-labeled drug. The oral absorption profile of unlabeled bidisomide was also studied after administration of a solution by a nasoenteric tube to different sites of the gastrointestinal tract (stomach, duodenum, jejunum, and ileum). The systemic availability was 61%. Absorption was slow initially and then rapid, achieving peak plasma concentrations between 2 and 4 hr. Less than complete systemic availability was attributed to incomplete absorption rather than first-pass metabolism. When the drug solution was delivered directly to the stomach, two distinct peak plasma levels were found. This was attributed to the more rapid absorption of bidisomide in the duodenum and ileum (and/or possibly colon). Following an iv dose, plasma levels of the drug declined with mean half-lives of 0.11, 2.0, and 12 hr for alpha, beta, and gamma phases, respectively, and a plasma clearance of 380 mL/min. The percentages of the dose recovered as bidisomide in urine and feces were 19 +/- 1 and 29 +/- 4 for the iv dose and 9.1 +/- 0.9 and 48 +/- 5 for the oral dose. Bidisomide did not exhibit substantial enantioselective pharmacokinetics in plasma regardless of the route of administration. The mean urinary excretion of the (-) enantiomer was, however, slightly higher than that of the (+) enantiomer, with (-)/(+) enantiomeric ratios of 1.2 and 1.3 after iv and oral administration, respectively. The enantiomeric ratio of bidisomide recovered in the feces was approximately 1.

Phagocytosis of myelin by microglia in vitro

Previous experiments from this laboratory have shown that peritoneal macrophages in culture will phagocytize myelin. Myelin preopsonized with myelin antibodies is phagocytized to a much greater extent than untreated myelin, indicating that macrophages ingest myelin by an Fc receptor. The present work was undertaken to determine the characteristics of myelin phagocytosis by microglia, the resident macrophages of the central nervous system. Microglia isolated from 4-5 day primary cultures of newborn rat brains were shown to bind and phagocytize myelin labeled in the lipids by 14C-acetate. Both binding and phagocytosis as shown by the appearance of 14C-cholesterol ester were greatly increased if labeled myelin was preopsonized with antiserum to myelin basic protein or galactocerebroside. Both preopsonized and untreated myelin were phagocytized more actively by microglia than by peritoneal macrophages under the same culture conditions. Microglia cultured in the presence of GM-CSF showed slightly increased cholesterol ester production from opsonized myelin, but the effect of GM-CSF was significantly greater than myelin pretreated with control serum (34% increase) or untreated myelin (154% increase). There was no significant effect of GM-CSF on myelin phagocytosis by peritoneal macrophages. Cerebrospinal fluid containing immunoglobulin drawn from rabbits with acute EAE also opsonized myelin to increase phagocytosis by microglia, as has been previously shown with peritoneal macrophages. These results indicate that microglia may actively participate in myelin destruction in demyelinating diseases where myelin antibodies or a source of GM-CSF may be present.

Genomic elements involved in transcriptional regulation of the rabbit surfactant protein-A gene

Expression of the surfactant protein-A (SP-A) gene is lung specific and is developmentally and hormonally regulated in fetal lung tissue. Cyclic AMP analogs and glucocorticoids stimulate transcriptional activity of the SP-A gene in fetal rabbit lung tissue in culture; an additive effect is observed when the agents are added in combination. To analyze the genomic regions that regulate SP-A promoter activity, fusion genes comprised of -1766, -991, -378, and -47 basepairs (bp) of DNA flanking the 5'-end of the SP-A gene, the transcription initiation site, and 20 bp of exon I linked to the human GH (hGH) structural gene were subcloned into a replication-defective human adenovirus vector and transfected into differentiated rat type II cells in primary culture. SP-A promoter activity was analyzed by RIA of hGH protein in the culture medium. In type II cells transfected with SP-A-1766:hGH and SP-A-991:hGH fusion genes, hGH production was induced 30- to 40-fold by (Bu)2AMP (Bt2cAMP; 1 mM). When type II cells were transfected with the SP-A-378:hGH fusion gene, basal levels of expression were reduced by more than 50%; however, Bt2cAMP caused an 11-fold increase in hGH production. In type II cells transfected with the SP-A-47:hGH fusion gene, basal levels of hGH production were essentially undetectable, and no stimulatory effect of Bt2cAMP was apparent. Cyclic AMP stimulation of expression of the SP-A-1766:hGH, SP-A-991:hGH, and SP-A-378:hGH fusion genes was limited to type II pneumonocytes in primary culture and was absent in two lung adenocarcinoma cell lines (NCl-H358 and A549), which do not express SP-A, and in cAMP-responsive adrenal Y1 cells. Mutations of a putative cAMP-responsive element (TGACCTCA) at -261 bp revealed its functional importance in mediating cAMP regulation of SP-A gene expression. Unexpectedly, dexamethasone (Dex; 10(-7) M) antagonized the stimulatory effect of Bt2cAMP on expression of SP-A:hGH fusion genes containing from -378 to -1766 bp of 5'-flanking DNA as well as that of a fusion gene construct containing -991 bp of 5'-flanking DNA, the first exon, the first intron, and 20 bp of the second exon (SP-A-991+670:hGH). The inhibitory effect of Dex was dose dependent, with half-maximal inhibition occurring at a Dex concentration of 8 x 10(-10) M. The inhibitory effect of Dex was prevented by the glucocorticoid receptor antagonist RU486.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential effect of interleukin-1 beta on Ia expression in astrocytes and microglia

In an earlier study we demonstrated the inhibitory effect of interleukin-1 beta (IL-1 beta) on human leukocyte antigens (HLA) class II enhancement by interferon-gamma (IFN-gamma) in a human glioblastoma multiforme cell line. In this study we have examined the effect of IL-1 beta on IFN-gamma induced major histocompatibility complex (MHC) class II (Ia) in primary cultures of newborn murine astrocytes and microglial cells. Astrocytes expressed very low levels of Ia molecules under basal culture conditions but these molecules could be induced with IFN-gamma. IL-1 beta in doses ranging from 1 to 100 units/ml inhibited the level of IFN-gamma induced Ia expression on astrocytes, and this inhibition was dose-dependent (mean maximum inhibition of 53 +/- 5% in number of positive cells and 53 +/- 2.6% in mean fluorescence intensity in four separate experiments). IL-1 beta treatment had no effect on MHC class I induction by IFN-gamma in the astrocytes. In contrast, microglial cells expressed Ia molecules under basal culture conditions, and this expression was enhanced by IFN-gamma treatment. Both basal and IFN-gamma induced Ia expression on microglia were resistant to IL-1 beta treatment in doses ranging from 1 to 100 units/ml. These results indicate that Ia expression is differentially regulated on astrocytes and microglial cells and that IL-1 beta may have an important immune regulatory function in the central nervous system.

Systemic histiocytosis presenting as multiple sclerosis

A patient resembling one with progressive multiple sclerosis in clinical presentation and by magnetic resonance imaging was studied in detail. Some features atypical for multiple sclerosis prompted a persistent search for an alternative cause. The diagnosis of a non-Langerhans systemic histiocytosis involving brain and bone was established and showed a partial response to radiation therapy. This patient illustrates the continued importance of a broad approach to the evaluation of possible multiple sclerosis, with particular attention to atypical features.

Orientation of the cleavage site of the herpes simplex virus glycoprotein G-2

During the synthesis of glycoprotein G-2 (gG-2) of herpes simplex virus type 2, the 104,000-Da gG-2 precursor (104K precursor) is cleaved to generate the 72K and the 31K intermediates. The 72K product is processed to generate the mature gG-2 (molecular mass, 108,000 Da), while the 31K product is additionally processed and secreted into the extracellular medium as the 34K component (H. K. Su, R. Eberle, and R. J. Courtney, J. Virol. 61:1735-1737, 1987). In this study, the orientations of the 31K and 72K products on the 104K precursor were determined by using two antipeptide sera produced in rabbits and a monoclonal antibody, 13 alpha C6, directed against gG-2. The sera prepared against synthetic peptides corresponding to the terminal amino acid residues 67 to 78 and an internal peptide at amino acids 247 to 260 of gG-2 recognized the 104K precursor and the 31K cleavage product but not the 72K intermediate. In contrast, 13 alpha C6 detected the 72K cleavage product and the uncleaved precursor but not the 31K cleavage component. The epitope recognized by 13 alpha C6 was mapped within amino acids 486 to 566. These results suggest that the 31K cleavage product is derived from the amino-terminal portion of the 104K precursor molecule and that the 72K intermediate is derived from the carboxyl terminus. In support of our model described above for the synthesis of gG-2, antibodies recognizing either of the cleavage products reacted with the uncleaved precursor but not with the other cleavage product. By using partial endo-beta-N-acetylglucosaminidase H analysis, two N-linked glycosylation sites were found on each of the cleavage products. The distribution of the N-linked glycosylation sites and the reactivities of the antipeptide sera allowed the cleavage region on the precursor to be mapped to within amino acids 260 to 437.