Inhibition of motor axon growth by T-cadherin substrata

As spinal motor neurons project to their hindlimb targets, their growth cones avoid particular regions along their pathway. T-cadherin is discretely distributed in the avoided caudal sclerotome and on extrasynaptic muscle surfaces (B. J. Fredette and B. Ranscht (1994) J. Neurosci. 14, 7331-7346), and therefore, the ability of T-cadherin to inhibit neurite growth was tested in vitro. T-cadherin inhibited neurite extension from select neuron populations both as a substratum, and as a soluble recombinant protein. Anti-T-cadherin antibodies neutralized the inhibition. Spinal motor neurons were inhibited only during the stages of axon growth across the sclerotome and muscle innervation. Inhibitory responses corresponded to neuronal T-cadherin expression, suggesting a homophilic binding mechanism. These results suggest that T-cadherin is a negative guidance cue for motor axon projections.     

Seminar planning guidelines. As I see it

Small local chapter groups can present quality cost effective regional seminars. Key components are dedication of members, teamwork, and a sense of direction. The following guidelines and information can provide a framework for planning and coordinating a seminar.     

Induced magnetic fields as evidence for subsurface oceans in Europa and Callisto

The Galileo spacecraft has been orbiting Jupiter since 7 December 1995, and encounters one of the four galilean satellites-Io, Europa, Ganymede and Callisto-on each orbit. Initial results from the spacecraft's magnetometer have indicated that neither Europa nor Callisto have an appreciable internal magnetic field, in contrast to Ganymede and possibly Io. Here we report perturbations of the external magnetic fields (associated with Jupiter's inner magnetosphere) in the vicinity of both Europa and Callisto. We interpret these perturbations as arising from induced magnetic fields, generated by the moons in response to the periodically varying plasma environment. Electromagnetic induction requires eddy currents to flow within the moons, and our calculations show that the most probable explanation is that there are layers of significant electrical conductivity just beneath the surfaces of both moons. We argue that these conducting layers may best be explained by the presence of salty liquid-water oceans, for which there is already indirect geological evidence in the case of Europa.     

Concentration-dependent changes in the latency and amplitude of somatosensory-evoked potentials by desflurane, isoflurane and sevoflurane

Despite improvement in early diagnosis, surgical techniques, and general patient care, most deaths of cancer patients result from metastases. Recent studies have revealed that cytokines produced by cancer cells or by stromal cells play an important role into development the cancer metastasis. The formation of a cancer metastasis involves several major steps: 1) extensive vascularization; 2) local invasion; 3) adherence either to capillary endothelial cells or to subendothelial basement membrane; 4) extravasation; and 5) proliferation. In colon cancer, several cytokines such as growth factors, inflammatory cytokines, and angiogenic factors have been confirmed to be involved in each step of metastasis. This paper summarizes the involvement of cytokines in the development of invasion and metastasis in colon cancer.     

A new class of tobacco chitinases homologous to bacterial exo-chitinases displays antifungal activity

A novel chitinase gene of tobacco was isolated and characterized by DNA sequence analysis of a genomic clone and a cDNA clone. Comparative sequence analysis of both clones showed an identity of 94%. The proteins encoded by these sequences do not correspond to any of the previously characterized plant chitinases of classes I-IV and are designated as class V chitinases. Comparison of the chitinase class V peptide sequence with sequences in the Swiss Protein databank revealed significant sequence similarity with bacterial exo-chitinases from Bacillus circulans, Serratia marcescens and Streptomyces plicatus. It was demonstrated that class V chitinase gene expression is induced after treatment of tobacco with different forms of stress, like TMV-infection, ethylene treatment, wounding or ultraviolet irradiation. Two related chitinase class V proteins of 41 and 43 kDa were purified from Samsun NN tobacco leaves inoculated with tobacco mosaic virus. The proteins were purified by Chelating Superose chromatography and gel filtration. In vitro assays demonstrated that class V chitinases have endo-chitinase activity and exhibit antifungal activity toward Trichoderma viride and Alternaria radicina. In addition, it was shown that class V chitinase acts synergistically with tobacco class I beta-1,3-glucanase against Fusarium solani germlings.     

The Dübendorf Study: a population-based investigation on normal values of blood pressure self-measurement

In a retrospective study of 50 consecutive children with posterior fossa tumors treated at Texas Children's Hospital, Houston, Tex., in 1989-1992, we evaluated perioperative factors which might influence the development of postoperative cerebrospinal fluid leaks. Factors analyzed included the presence of preoperative hydrocephalus, the institution of cerebrospinal fluid diversion, and the method of dural closure. No statistically significant impact on subsequent cerebrospinal fluid leakage was demonstrated.     

Some aspects of the role of coal thermoplasticity and coke structure in coal gasification. 2. The effects of pressure and heating rate on dilatometric parameters and optical anisotropy development

An examination of the influence of pressure and heating rate on the thermoplastic properties of a weakly coking coal and of coal with various pitch-like additives was carried out using a high pressure dilatometer. Pressure up to 4 MPa markedly increased the swelling properties and increased the plastic range by decreasing the softening temperature, but the effects of pressure were strongly influenced by rate of heating with high heating rates enhancing the effects. Additions of tar or pitch also enhanced swelling at low pressure. The solid carbonization residues from the dilatometer were examined by polarized light microscopy to determine the content and composition of optically anisotropic species. The anisotropic content was increased by increases in pressure and heating rate and pitch additives enhanced the anisotropic content, especially at low pressure, without affecting the composition of the anisotropy. No direct correlations exist between the dilatometric parameters and the optical anisotropy but their dependence on the conditions emphasizes that when considering high pressure gasification of coal, it is necessary to obtain data under appropriate conditions.     

The ageing Australian firefighter: an argument for age-based recruitment and fitness standards for urban fire services

Currently, there is no enforcement of physical standards within Australian fire services post-recruitment, possibly leading to inappropriate fitness and body composition. This study evaluated the impacts of ageing on physical standards of Australian firefighters. Seventy-three firefighters from three different 10-year age groups [25–34 years (n = 27), 35–44 years (n = 27), 45–54 years (n = 19)] volunteered for physical testing using dual-energy X-ray analysis and existing fitness tests used for recruitment by an Australian fire service. Older (45–54 years) participants demonstrated significantly poorer physical standards compared with younger participants including cardiovascular fitness (p < 0.05), strength (p = 0.001) and simulated operational power testing tasks (p < 0.001). Age-related body composition changes were also observed independent of body mass index. Minimum recruitment standards and fitness programs need to account for age-related declines in physical capabilities to ensure that the minimum standard is maintained regardless of age.

Practitioner Summary: Using dual-energy X-ray analysis and established fitness testing protocols, this study aimed to gain an appreciation of the current standards of body composition and fitness of Australian firefighters and the effects of ageing on their physical abilities post-recruitment. The study demonstrated a significant decline in physical standards due to age.     

Partial oxidation of methane to methanol-comparison of heterogeneous catalyst and homogeneous gas phase reactions

Potential catalysts for the partial oxidation of methane to methanol have been synthesised and tested in high pressure annular reactors. Uranium oxide and molybdenum oxide catalysts and iron sodalite catalyst have been tested under the conditions reported in the patents and under conditions which allow comparison with reactions carried out in the gas phase. None of the catalysts tested showed an improvement on the gas phase results. It was found that the oxidative nature of the metal oxide catalysts is an inherent feature which reduces the selectivity to methanol.     

Desulphurization of coals and chars by treatment in various atmospheres between 400 and 600 °C

Desulphurization of fifteen US coals of rank ranging from anthracite to sub-bituminous B and five high-temperature chars by carbon monoxide and other gases and gas mixtures between 400 and 600 °C has been studied. The sulphur content of the parent coals ranged between 3.0 and 7.3% and that of the chars between 1.3 and 3.8% by weight. A comparison between air, nitrogen, carbon monoxide, and steam-carbon monoxide mixtures as desulphurizing gases shows the order of desulphurizing ability as

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