Modelling of wicking and moisture interactions of flax and viscose fibres.

Methods for assessing the wicking properties of individual fibre bundles have been developed from models based on the original Washburn equation (WE) and the modified Washburn equation (MWE), which also accounts for swelling. Both models gave indication of differences in wicking properties of flax and the viscose fibres, though MWE gave additional information that could be interpreted in terms of the physical model. Wicking of the viscose fibres is mainly via inter-fibre capillaries while that of flax is a combination of inter-fibre capillaries and lumen present in some elementary fibres. The degree of swelling and associated rotation of flax fibre in a vapour pressure range of 1-6torr were monitored using an environmental scanning electron microscope (ESEM). Viscose fibre exhibited swelling under the same conditions but did not rotate. The two techniques highlighted different mechanisms of wicking which can be used for monitoring moisture uptake/swelling of treated fibres for fabrication of composites.

HPNS seizure risk: a role for the Golgi-associated retrograde protein complex?

Previous attempts to characterize the genetic contribution to differential risk of developing the HPNS seizure in a mouse model system are extended to additional data and an analytical mode that incorporates the set of linked resources for systems genetics in the GeneNetwork project. A quantitative trait locus (QTL) affecting HPNS seizure phenotype was mapped to a approximately 6 megabase (Mb) gene-rich region of Chr 17 based on the degree of expression covariation among genes in the region of the QTL and genes in the brains of BXD recombinant inbred mice in the same chromosomal region. Use of GeneNetwork's WebQTL analytical modules revealed that among > 220 positional candidate genes, vacuolar protein sorting gene 52 (Vps52) has highest priority. It appears that a single nearly null mutation in a distal region of Vps52 3'UTR (untranslated region) defined by a DNA probe set is associated with > 60% of the seizure risk difference between the high- and low-risk strains DBA/2 and C57BL/6, respectively. Based on the known contribution of the elements of the GARP complex--Vps52, -53 and -54--to motoneuron abnormalities, mutation-depleted Vps52 may be implicated in HPNS seizure risk variation in the mouse and, by gene homology, also with human VPS52.

The combined effects of high pressure and nisin on germination and inactivation of Bacillus spores in milk.

AIMS: The aim of this work was to investigate the germination and inactivation of spores of Bacillus species in buffer and milk subjected to high pressure (HP) and nisin. METHODS AND RESULTS: Spores of Bacillus subtilis and Bacillus cereus suspended in milk or buffer were treated at 100 or 500 MPa at 40 degrees C with or without 500 IU ml(-1) of nisin. Treatment at 500 MPa resulted in high levels of germination (4 log units) of B. subtilis spores in both milk and buffer; this increased to >6 logs by applying a second cycle of pressure. Viability of B. subtilis spores in milk and buffer was reduced by 2.5 logs by cycled HP, while the addition of nisin (500 IU ml(-1)) prior to HP treatment resulted in log reductions of 5.7 and 5.9 in phosphate buffered saline and milk, respectively. Physical damage of spores of B. subtilis following HP was apparent using scanning electron microscopy. Treating four strains of B. cereus at 500 MPa for 5 min twice at 40 degrees C in the presence of 500 IU ml(-1) nisin proved less effective at inactivating the spores of these isolates compared with B. subtilis and some strain-to-strain variability was observed. CONCLUSIONS: Although high levels of germination of Bacillus spores could be achieved by combining HP and nisin, complete inactivation was not achieved using the aforementioned treatments. SIGNIFICANCE AND IMPACT OF THE STUDY: Combinations of HP treatment and nisin may be an appealing alternative to heat pasteurization of milk.

Physical degradation of wheat straw by the in-vessel and windrow methods of mushroom compost production.

Mushroom compost manufacturers in Ireland are moving away from the traditional outdoor phase I windrow method, favouring in-vessel production. Composters and growers have reported better quality compost with faster spawn run and higher yields produced by this process. In the present study, physical examination of samples highlighted differences when comparing the windrow and in-vessel methods of compost production. Observations using scanning electron microscopy suggest that the cuticle of wheat straw from in-vessel production is damaged during phase I, peeling away from the surface in fragments, and exposing the epidermis. Changes in silicon levels on the straw surface acted as a marker for cuticle damage when comparing both composting systems. Cuticle damage may be important during composting and afterwards, as substrate colonisation is faster, and consequently spawn run is shorter. The phase I compost microbial community is altered by the in-vessel technique, producing a predominantly thermophilic bacterial flora in contrast to the mesophilic and thermophilic bacteria and fungi found in windrow phase I compost. These differences may be significant in mushroom compost production.

Inheritance of hypoxic exercise tolerance in mice.

All mammals tested, when exposed acutely to a degree of hypoxia above some threshold, exhibit a reduced capacity to perform work. Chronic hypoxic exposure is usually associated with some degree of acclimation resulting in partial recovery of the preexposure work capacity. The present study reports that, among mice, interindividual variability in recovery of ability to tolerate a standardized hypoxic exercise [t(et); time elapsed in treadmill exercise in hypoxia until 4-s failure to avoid a grid configured to deliver a mild aversive current (0.15 mA)], after 8 weeks' exposure to half-atmospheric pressure, is influenced predominantly by two unlinked genes of major effect. Two approaches were taken toward genetic characterization. In one, a maximum-likelihood procedure was applied to 11 models of genetic determinacy in the t(et) distributions of BALB/cBy (C) and C57BL/6By (B6) parental inbred strains, their F1 hybrid, and the backcross (BC) generations. Breeding tests of the resulting candidate "best-fit" major locus inheritance models involved repeated cycles of selecting, as the progenitor of a new BC generation, the male with the highest value of the test variable in the previous BC generation, and breeding him to C females. Mice from each of four distinct phenotypes appearing in BC3 were bred to C mice, producing distributions expected from two-locus segregation. The second approach was based upon CXB/By RI strain distribution pattern and derivative breeding tests to reveal phenotypic distributions consistent with two-locus inheritance of tet. Melding these results with a positional cloning strategy may permit relating a behavioral difference to specific heritable elements and identifying their products as the (partial) physiological substrata of the behavior.

Tissue interleukin 1 and interleukin-1 receptor antagonist expression in enterocolitis in resistant and susceptible rats.

BACKGROUND/AIMS: Subserosal injection of purified group A streptococcal peptidoglycan-polysaccharide (PG-APS) induces chronic relapsing granulomatous enterocolitis and systemic inflammation in susceptible inbred Lewis rats but only transient intestinal injury in Buffalo and Fischer rats. Cecal interleukin 1 (IL-1) and IL-1 receptor antagonist (IL-1ra) expression was measured in inbred rats displaying differential susceptibility to experimental enterocolitis. METHODS: The ileum and cecum of Lewis, Buffalo, and Fischer rats were subserosally injected with purified PG-APS or albumin. IL-1 and IL-1ra messenger RNA (mRNA) and protein (IL-1 only) were measured 1 or 27 days later. PG-APS-injected Lewis rats were treated with recombinant human IL-1ra. Kinetics of IL-1 and IL-1ra mRNA expression were studied in peritoneal cells. RESULTS: All rats strains developed acute inflammation with increased cecal concentrations of IL-1 beta and IL-1ra mRNA. Lewis rats developed chronic enterocolitis and had higher IL-1 and IL-1ra mRNA tissue levels than Buffalo or Fischer rats, which displayed no chronic inflammation. IL-1 beta and IL-1ra were produced by submucosal granulomas and correlated with inflammation. IL-1 alpha protein levels paralleled IL-1 beta mRNA expression. IL-1ra treatment attenuated acute and chronic enterocolitis, adhesions, and arthritis. PG-APS induced IL-1 and IL-1ra expression in peritoneal cells from Lewis and Fischer rats. CONCLUSIONS: Bacterial cell wall polymers stimulate IL-1 and IL-1ra expression in vivo and in vitro. These counterbalancing cytokines are increased in experimental enterocolitis and have important immunoregulatory roles in intestinal inflammation.

Insulinlike growth factor I and interleukin 1 beta messenger RNA in a rat model of granulomatous enterocolitis and hepatitis.

BACKGROUND: Insulinlike growth factor I (IGF-I) is mitogenic for fibroblasts and smooth muscle cells and stimulates collagen synthesis. The present study tested the hypothesis that IGF-I is important in the development of granulomatous inflammation and fibrosis. METHODS: IGF-I messenger RNA (mRNA) was measured in bowel and liver of rats with peptidoglycan-polysaccharide-induced chronic granulomatous enterocolitis and hepatitis using RNase protection. Cellular sites of IGF-I mRNA and IGF-I peptide precursor were localized by in situ hybridization and immunohistochemistry, respectively. Sites of IGF-I synthesis were compared with sites of interleukin 1 beta mRNA expression. RESULTS: IGF-I mRNA was increased 3.7-fold in cecal tissue from peptidoglycan-polysaccharide-injected rats compared with controls. IGF-I mRNA was up-regulated in fibroblastlike cells in the intensely fibrotic periphery of cecal and hepatic granulomas. This region also expressed IGF-I peptide precursor. Interleukin 1 mRNA localized to macrophage-like cells in the center of granulomas. CONCLUSIONS: IGF-I may be important in the development of fibrosis in this model of Crohn's disease. The localization of IGF-I and interleukin 1 mRNAs to distinct but adjacent sites is consistent with a paracrine interaction between cells expressing IGF-I and interleukin 1.

A 'safe-site' for Salmonella typhimurium is within splenic cells during the early phase of infection in mice.

Salmonella typhimurium infection in mice is focused on the spleen and liver, and prolonged infection can lead to sepsis and death. After intravenous infection with a moderate dose of S. typhimurium, the few bacteria that survive in the spleen and liver grow in a 'safe-site' where they are protected from immune destruction. In this study, we demonstrated that the lack of killing of resident salmonella in the spleen and liver was not because the salmonella were transformed within the host and became resistant to killing, or because the infected mice lost the ability to kill salmonella. We showed that the salmonella were within an intracellular 'safe-site' that protected them from killing. Brief treatment of salmonella-infected mice with gentamicin reduced the numbers of salmonella in the blood but had no effect on the numbers in the liver and spleen, suggesting an intracellular location of the salmonella. After dissociation of spleen cells from recently infected mice, 60% of the salmonella remained cell associated. These cell-associated salmonella, unlike cell-free salmonella, were resistant to killing by gentamicin. The cell-associated salmonella were rendered susceptible to gentamicin after sonication, providing confirmation of their previous intracellular location.

An electron microscopic analysis of the morphology and connectivity of individual HRP-labeled slowly adapting vibrissa primary afferents in the adult rat.

The ultrastructure of 4 slowly adapting vibrissa primary afferent central terminal arbors was examined following intracellular injection of horseradish peroxidase (HRP). The terminals were found to contain clear round vesicles and formed primarily asymmetric synapses on dendritic shafts and spines. Few examples of synaptic glomeruli, with the labeled axon as the central element, were identified.

Ultrastructural abnormalities in the germinal epithelium of adult quail testes following insecticide chlordecone exposure.

Sexually mature male Japanese quail were treated with either 40.0 micrograms estradiol-17b injected intraperitoneally or 10 ppm, 40 ppm, 80 ppm, 160 ppm, or 200 ppm chlordecone (Kepone) administered in feed for 60 days. Animals were sacrificed on days 10, 30, and 60 and the germinal epithelium was measured morphometrically and examined with transmission electron microscopy. Estradiol had a minimal effect on testicular morphology whereas there was a dose- and time-dependent reduction in germinal epithelium height in all birds following 60 days of chlordecone exposure. Exposure of quail to higher chlordecone doses (80, 160 and 200 ppm) for 30 or 60 days did not alter the ultrastructure of spermatogenic and Sertoli cells in the basal compartments; however, numerous maturing spermatid clumps located in the adluminal compartments of the germinal epithelium exhibited increased vacuolation, cytoplasmic degeneration and desquamation. Since some of the abnormal spermatids were closely associated with Sertoli cells, the possible role of Sertoli cells during pesticide exposure is discussed.

Genetic association of defects in macrophage larvicidal activity and vaccine-induced resistance to Schistosoma mansoni in P strain mice.

In contrast to most inbred strains, P mice fail to develop significant resistance to Schistosoma mansoni infection as a result of vaccination with irradiated cercariae. Vaccinated P mice also exhibit a defect in macrophage activation for killing of larval schistosomes upon specific-antigen challenge in vivo. To examine the genetic basis of these defects in vaccine-induced immunity, inheritance of the two traits was examined in (C57BL/6 X P)F1, F2, and reciprocal backcross generations. The defect in macrophage function which characterizes the P strain parent was found to be inherited in a fully recessive manner and to be controlled by only one or two major genetic loci. Moreover, a highly significant correlation (P less than 0.0025) was observed between the level of macrophage larvicidal activity and the level of resistance to challenge infection in segregating generations. Such an association is consistent with a cause-and-effect relationship, providing strong in vivo evidence implicating activated macrophages as immune effector cells of resistance to S. mansoni in the mouse-irradiated-vaccine model.

Macrophage chemotactic response in mice is controlled by two genetic loci.

The level of the in vitro chemotactic responsiveness of murine inflammatory peritoneal macrophages is dependent upon the genetic background of the host. A survey of the responses of macrophages from various inbred strains showed three categories of response (high, intermediate, and low), indicating that genetic control is multigenic. Among the high responder strains were those derived from the C57BL (B) background, while mice of the A/J (A) strain exhibited the lowest response. In order to determine the number of genes controlling the level of macrophage chemotactic responses, segregation analysis of backcross mice derived from high responder B and low responder A parental mice was performed. The results of analysis of the data by the maximum likelihood modeling, a computerized method, showed that the difference in macrophage chemotactic responsiveness in the strain combination of B and A mice is due to the effects of two autosomal genetic loci.

High pressure neurologic syndrome type 2 seizure in mice.

Progressive compression in helium/oxygen (heliox) atmospheres elicits in mice and many other vertebrates tested a complex series of effects known as the high pressure neurologic syndrome (HPNS). The most dramatic behavioral manifestations of the syndrome are two successive and distinct convulsive seizures. HPNS type 1 and type 2. In the present study, a maximum likelihood estimation procedure was applied to 11 models of inheritance of the difference in the time elapsed until manifestation of the type 2 seizure in heliox-compressed C57BL/6 and BALB/c mouse strains, their F1 hybrid, and the backcross generations. The "preferred" model specifying interaction between two major unlinked autosomal loci was confirmed indirectly by further breeding tests. The tests also showed that type 1 and type 2 seizure thresholds are uncorrelated but type 1 always preceded type 2. A challenge to the latter result involving mating backcross mice with high type 1 and type 2 seizure thresholds to mice with low type 1 and type 2 seizure thresholds produced no instance of alteration of the seizure order.

Scanning electron microscopy of dairy equipment surfaces contaminated by two milk-borne micro-organisms.

Ethanol dehydration followed by argon replacement induced drying (ARID) was found to be a suitable method for the preparation of glass, stainless steel and rubber surfaces which had been in contact with inoculated milk and which were to be examined using scanning electron microscopy (SEM). This technique was used to examine samples of all three materials which had been subjected to both single and repeated inoculation with whole milk containing a Pseudomonas sp. or a Micrococcus sp. and incubated for various periods. Some samples were also prepared for SEM using a cryofixation technique. The Pseudomonas sp. was found to proliferate on glass and stainless steel surfaces but not on rubber. Due to the clumping tendency of the Micrococcus sp. proliferation of this organism was more difficult to assess accurately. In general there was no difference in results obtained between single and repeated inoculation. Various factors which may have aided attachment of micro-organisms to surfaces were identified viz., surface channels present in stainless steel, milk deposits and the production of extracellular material. The value of using both the cryofixation and chemical preparatory techniques for the identification of artifacts is discussed.

Evidence that two loci predominantly determine the difference in susceptibility to the high pressure neurologic syndrome type I seizure in mice.

Most mammals tested, when exposed to increasing pressure in helium/oxygen atmospheres, exhibit progressive motor disturbances culminating in two, usually successive, well-differentiated convulsive seizures. The seizures are highly reproducible components of the constellation of events that collectively constitute the High Pressure Neurologic Syndrome (HPNS). In the present study, we present evidence that the mean difference in seizure threshold pressures of the first seizure to occur (HPNS Type I) between inbred mouse strains DBA/2J and C57BL/6J is predominantly determined (greater than 60%) by the expression of a major locus-possibly linked to the H-2 locus on chromosome 17- and a minor locus, probably unlinked. This outcome is derived from applications of the maximum likelihood modeling procedure of ELSTON and STEWART (1973) and STEWART and ELSTON (1973) to eleven models of genetic determinacy and tests (including breeding tests) of "preferred" models so derived using BXD recombinant inbred strains that show the following: The major locus exhibits conditional dominance characteristics depending upon compression rate and minor locus genotype. At a constant mean compression rate of 100 atm hr-1, the major locus manifests strong, though incomplete, dominance apparently independent of minor locus genotype. Its expression is, however, highly sensitive to compression rate, losing its dominance altogether at a linear rate of 1,000 atm hr-1. The major locus interacts with the weakly dominant and relatively compression-rate-insensitive minor locus to retain dominance at fast compression only when the dominant alleles of both loci are present. A principal finding of this study is that employing two compression rates permits fuller genetic characterization of murine high-pressure seizure susceptibility differences than could be achieved by use of a single compression rate.

Comparative physiology of the high-pressure neurological syndrome--compression rate effects.

The effect of compression rate on onset of high-pressure convulsions has been studied in 14 vertebrate species, as well as in 10 mouse strains and 4 rat strains. Compression rate effects were observed in 9 of the 14 species. They appear to be independent of exposure temperature, correlate only very loosely with phylogenetic position, and appear to reflect species-specific compensatory mechanisms grafted onto an underlying convulsion-producing effect of high hydrostatic pressure. Five vertebrate species distributed among three of the four classes tested failed to show a significant degree of compression rate dependence of high-pressure neurological syndrome (HPNS) convulsion thresholds. The implications of this finding for the formulation of hypotheses regarding the biophysical basis for HPNS convulsions has been discussed. Comparison of intrinsic HPNS susceptibility in different species, in the light of these findings, requires that the comparison be made at a common compression rate. Four of the five lower vertebrate species fall consistently into the category showing high HPNS convulsion threshold pressures regardless of the compression rate employed, whereas the two primates and the one carnivore tested equally consistently fall in the low convulsion threshold pressure category. The data suggest a parallel between the degree of brain development and the relative HPNS susceptibility of a given species and contrast with the inverse relations observed during maturation of newborn mice and rats. The results are compared with data for other convulsants and suggest grouping HPNS and pentylenetetrazole seizures as against electroshock, hyperoxic, flurothyl, strychine, or picrotoxin convulsions.