Control of Root-knot Nematodes on Tomato by Lectins

Significant control of tomato root knot was achieved by applications of the lectins Concanavalin A (Con A) and Limax flavus agglutinin in greenhouse, growth chamber, and microplot trials. Four consecutive weekly applications at lower concentrations of Con A yielded better control than single applications at a higher total concentration. The present state of knowledge on binding of Con A to soil nematodes and the in vitro effect of this lectin in chemotactic behavior are discussed. The mode of action of Con A on root-knot control is unknown.     

Establishment and characterization of murine macrophage hybrids

Proteose peptone-induced peritoneal macrophages from CBA/J (H-2k) mice have been fused to a hypoxanthine phosphoribosyltransferase-negative variant of the P388D1 (H-2d) murine macrophage cell line. Six hybrid clones were isolated following HAT selection and further characterized. Five of the six clones express class I antigens of both parental haplotypes by microelisa and by flow cytometric analysis. Class II antigen expression of both haplotypes was apparent following a 72-hr incubation of the hybrids with concanavalin A-stimulated rat spleen cell supernatant. However, I-Ad was expressed in all hybrids to a greater extent than I-Ak. Three clones with the highest level of I-Ak expression, E5, C2, and C4, were capable of antigen presentation to the I-Ak-restricted T-cell line, D10.G4.1. LPS induction of the hybrids resulted in a 2- to 15-fold increase in the amount of IL-1 produced relative to the P388D1 parent. Finally, in distinction to P388D1, all hybrids demonstrated increased Fc-mediated erythrophagocytosis of chromium-labeled antibody-coated erythrocytes. These murine macrophage hybrids appear stable and should serve as useful models in understanding the regulation of macrophage function.     

Fluorescent and Ferritin Labelling of Cuticle Surface Carbohydrates of Caenorhabditis elegans and Panagrellus redivivus

Caenorhabditis elegans and Panagrellus redivivus were investigated for surface carbohydrates using fluorescent-labelled and ferritin-labelled lectins. Rhodamine-labelled Concanavalin A was specifically located in the cephalic region of both species. Rhodamine-labelled wheat germ agglutinin was located over the entire cuticle of P. redivivus but was absent on C. elegans. Rhodamine-labelled peanut agglutinin and Limax flavus agglutinin did not label nematodes of either species. Galactose and sialic acid were not detected on either species, whereas mannose-glucose residues were specifically localized in the head areas of both species. No detectable N-acetylglucosamine occurred on C. elegans, but it was evenly distributed over the cuticle surface of P. redivivus.     

Differential Adhesion and Infection of Nematodes by the Endoparasitic Fungus Meria coniospora (Deuteromycetes)

The conidia of the endoparasitic fungus Meria coniospora (Deuteromycetes) had different patterns of adhesion to the cuticles of the several nematode species tested; adhesion in some species was only to the head and tail regions, on others over the entire cuticle, whereas on others there was a complete lack of adhesion. After adhesion, the fungus usually infected the nematode. However, adhesion to third-stage larvae of five animal parasitic nematodes, all of which carry the cast cuticle from the previous molt, did not result in infection. M. coniospora infected animal parasitic nematodes when this protective sheath was removed. Seven preparations of sialic acid (N-acetylneuraminic acid) gave three types of response in adhesion-infection of nematodes: (i) a significant reduction in conidial adhesions; (ii) no interference with adhesion, but a 10-day delay in infection; and (iii) a delay in infection by 2 to 3 days. The current results support previous findings indicating involvement of sialic acids localized on nematode cuticles in recognition of prey by M. coniospora.     

Ultrastructural Studies on Caenorhabditis briggsae

A study of the fine structure of Caenorhabditis briggsae revealed several features not previously described in free-living nematodes. These were: chambered walls of the stoma, zonula adherens in the esophagus, daedaloid folds in the inner surface of the uterus and openings in the terminal web of the intestinal epithelium. Other structures observed in these studies were similar to those described from other free-living nematodes.     

Dose-response relationship of the cardiovascular adaptation to endurance training in healthy adults: how much training for what benefit?

Occupational or recreational exercise reduces mortality from cardiovascular disease. The potential mechanisms for this reduction may include changes in blood pressure (BP) and autonomic control of the circulation. Therefore, we conducted the present long-term longitudinal study to quantify the dose-response relationship between the volume and intensity of exercise training, and regulation of heart rate (HR) and BP. We measured steady-state hemodynamics and analyzed dynamic cardiovascular regulation by spectral and transfer function analysis of cardiovascular variability in 11 initially sedentary subjects during 1 yr of progressive endurance training sufficient to allow them to complete a marathon. From this, we found that 1) moderate exercise training for 3 mo decreased BP, HR, and total peripheral resistance, and increased cardiovascular variability and arterial baroreflex sensitivity; 2) more prolonged and intense training did not augment these changes further; and 3) most of these changes returned to control values at 12 mo despite markedly increased training duration and intensity equivalent to that routinely observed in competitive athletes. In conclusion, increases in R-wave-R-wave interval and cardiovascular variability indexes are consistent with an augmentation of vagal modulation of HR after exercise training. It appears that moderate doses of training for 3 mo are sufficient to achieve this response as well as a modest hypotensive effect from decreasing vascular resistance. However, more prolonged and intense training does not necessarily lead to greater enhancement of circulatory control and, therefore, may not provide an added protective benefit via autonomic mechanisms against death by cardiovascular disease.     

Immune response to a new hepatitis B vaccine in healthcare workers who had not responded to standard vaccine: randomised double blind dose-response study.

OBJECTIVE: To evaluate the immunogenicity and reactogenicity of a new triple S recombinant hepatitis B vaccine in a cohort of healthy people in whom currently licensed hepatitis B vaccines had persistently not induced an immune response. DESIGN: Single centre, randomised, double blind, dose-response study. SETTING: Research vaccine evaluation centre at a teaching hospital. SUBJECTS: 100 healthcare workers aged 18-70 years with a history of failure to seroconvert after at least four doses of a licensed hepatitis B vaccine containing the S component. INTERVENTION: Each subject was randomly allocated two doses of 5, 10, 20, or 40 micrograms of a new hepatitis B vaccine two months apart. MAIN OUTCOME MEASURES: Immunogenicity of the four doses. Seroconversion and seroprotection were defined as an antibody tire > 10 IU/l and > 100 IU/l respectively against an international antibody standard. RESULTS: 69 subjects seroconverted after a single dose of the vaccine. After the booster vaccination one other subject seroconverted, bringing the overall seroconversion rate to 70%. Fifteen subjects given 5 micrograms of vaccine, 19 given 10 micrograms, 16 given 20 micrograms, and 20 given 40 micrograms seroconverted. Seroconversion rates in the four antigen dose groups were 60% (15/25), 76% (19/25), 64% (16/25), and 80% (20/25). After the booster dose there was no significant dose-response effect on the overall seroconversion rate, although the small sample size meant that a clinically important dose-response could not be ruled out. CONCLUSION: A single dose of 20 micrograms of the vaccine was as effective as two doses of either 40 micrograms or 20 micrograms of this vaccine formulation in terms of seroconversion, seroprotection, and geometric mean titres.     

Pulmonary vascular impedance and wave reflections in the hypoxic calf.

The alterations in pulsatile hemodynamics that occur during hypoxic pulmonary vasoconstriction have not been well characterized. Changes in oscillatory hemodynamics, however, may affect right ventricular-pulmonary vascular coupling and the dissipation of energy within the lung vasculature. To better define hypoxic pulsatile hemodynamics, we measured main pulmonary artery proximal and distal micromanometric pressures and ultrasonic flow in four open-chest calves during progressive hypoxia. Main pulmonary artery impedance and pressure transmission spectra were calculated using spectral analysis methods. Measured pressure and flow signals were separated in the time domain into forward and backward components. Hypoxia increased pulmonary blood pressure and resistance and produced multiple modifications in the impedance and pressure transmission spectra that indicated increased wave reflections and elasticity. The impedance and apparent phase velocity first-harmonic values were increased in amplitude, and the pressure transmission modulus plot showed an increased peak value. In addition, the impedance modulus plot demonstrated a rightward shift and increased oscillation in the mid- to high-frequency range. The time domain analysis also confirmed increased wave reflections and elasticity. Hypoxia produced large backward-traveling (reflected) pressure and flow waves. The initial portions of these waves arrived at the heart during systole, producing characteristic changes in the measured pressure and flow waveforms. With prolonged hypoxia, main pulmonary artery pulse wave velocity increased by 30%. Thus, hypoxia is associated with complex alterations in pulmonary artery elasticity and wave reflections that act to increase the oscillatory afterload of the right ventricle.