Soluble human complement receptor type 1: in vivo inhibitor of complement suppressing post-ischemic myocardial inflammation and necrosis

The complement system is an important mediator of the acute inflammatory response, and an effective inhibitor would suppress tissue damage in many autoimmune and inflammatory diseases. Such an inhibitor might be found among the endogenous regulatory proteins of complement that block the enzymes that activate C3 and C5. Of these proteins, complement receptor type 1 (CR1; CD35) has the most inhibitory potential, but its restriction to a few cell types limits its function in vivo. This limitation was overcome by the recombinant, soluble human CR1, sCR1, which lacks the transmembrane and cytoplasmic domains. The sCR1 bivalently bound dimeric forms of its ligands, C3b and methylamine-treated C4 (C4-ma), and promoted their inactivation by factor I. In nanomolar concentrations, sCR1 blocked complement activation in human serum by the two pathways. The sCR1 had complement inhibitory and anti-inflammatory activities in a rat model of reperfusion injury of ischemic myocardium, reducing myocardial infarction size by 44 percent. These findings identify sCR1 as a potential agent for the suppression of complement-dependent tissue injury in autoimmune and inflammatory diseases.     

Intelligent tutoring systems

Cognitive psychology, artificial intelligence, and computer technology have advanced to the point where it is feasible to build computer systems that are as effective as intelligent human tutors. Computer tutors based on a set of pedagogical principles derived from the ACT theory of cognition have been developed for teaching students to do proofs in geometry and to write computer programs in the language LISP.     

Interspecific hybrids of Zinnia elegans Jacq. and Z. angustifolia HBK: embryology,morphology and powdery mildew resistance

Summary Reciprocal crosses between 13 cultivars of Zinnia elegans Jacq. and one source of Z. angustifolia HBK resulted in interspecific hybrids. Florets examined 14 days after pollination showed that all 13 cross combinations of Z. angustifolia x Z. elegans yielded embryos in 47.2% of the florets pollinated. Six cross combinations of Z. elegans x Z. angustifolia produced embryos in 4.6% of the total Z. elegans florets pollinated. Interspecific crosses resulted in seed-propagated hybrids when Z. angustifolia was the maternal parent. Hybrids were obtained from reciprocal crosses between the two species when embryos were excised and cultured. Morphologically, most hybrids resembled Z. angustifolia but were sterile. Colchicine treatments of selected sterile hybrids resulted in shoots producing fertile inflorescences. Preliminary tests showed that hybrids were resistant to powdery mildew (Erysiphe cichoracearum DC ex Mecat).Scientific Article No. A 3108, Contribution No. 6173 of the Maryland Agricultural Experiment Station, Department of Horticulture.     

The disappearing Dry Chaco,one of the last dry forest systems on earth

Landscape Ecology - The Dry Chaco spans more than 87 million hectares across Argentina, Bolivia, and Paraguay. This unique forest system has experienced extensive loss and fragmentation due to...     

The earthworm population of a winter cereal field and its effects on soil and nitrogen turnover

The earthworm population in a winter cereal field in Ireland was studied over a 3-year-period and its effects on soil and N turnover were assessed. The mean annual population density was 346–471 individuals m^-2 and the mean biomass was 56.9–61.2 g m^-2. Twelve species were recorded, the most abundant being Allolobophora chlorotica followed by Aporrectodea caliginosa, and 242 mg at 5°C to 713 mg at 10°C in the case of juvenile Lumbricus terrestris. Gut contents (dry mass of soil) comprised 6.7–15.5% of the A. caliginosa live mass, and 9.7–14.7% of the Lumbricus terrestris mass. Annual soil egestion by the field population was estimated as 18–22 kg m^-2. Tissue production ranged from 81.7 to 218.5 g m^-2, while N turnover resulting from mortality was calculated as 1.5–3.9 g m^-2 depending on the year and the method of calculation. Earthworms were estimated to contribute an additional 3.4–4.1 g mineral N to the soil through excretion, mucus production, and soil ingestion. Independent estimates of N output via mucus and excretion derived from ¹⁵N laboratory studies with Lumbricus terrestris were 2.9–3.6 g m^-2 year^-1.     

Live Brucella abortus rough vaccine strain RB51 stimulates enhanced innate immune response in vitro compared to rough vaccine strain RB51SOD and virulent smooth strain 2308 in murine bone marrow-derived dendritic cells

Brucella spp. are Gram-negative, coccobacillary, facultative intracellular pathogens. B. abortus strain 2308 is a pathogenic strain affecting cattle and humans. Rough B. abortus strain RB51, which lacks the O-side chain of lipopolysaccharide (LPS), is the live attenuated USDA approved vaccine for cattle in the United States. Strain RB51SOD, which overexpresses Cu–Zn superoxide dismutase (SOD), has been shown to confer better protection than strain RB51 in a murine model. Protection against brucellosis is mediated by a strong CD4+ Th₁ and CD8+ Tc₁ adaptive immune response. In order to stimulate a robust adaptive response, a solid innate immune response, including that mediated by dendritic cells, is essential. As dendritic cells (DCs) are highly susceptible to Brucella infection, it is possible that pathogenic strains could limit the innate and thereby adaptive immune response. By contrast, vaccine strains could limit or bolster the innate and subsequent adaptive immune response. Identifying how Brucella vaccines stimulate innate and adaptive immunity is critical for enhancing vaccine efficacy. The ability of rough vaccine strains RB51 and RB51SOD to stimulate DC function has not been characterized. We report that live rough vaccine strain RB51 induced significantly better (p ≤ 0.05) DC maturation and function compared to either strain RB51SOD or smooth virulent strain 2308, based on costimulatory marker expression and cytokine production.     

Production of Brucella abortus-specific protein A-reactive antibodies (IgG2) in infected and vaccinated cattle

The IgG2 anti-Brucella antibody response of cattle to Brucella vaccination and infection was measured. Three groups of animals were studied; Group 1 contained 11 non-vaccinated cows, Group 2, 17 cows vaccinated with a low dose of Strain 19 vaccine and Group 3, 17 cows vaccinated with a high dose of Strain 19 vaccine. All animals were challenged at Week 33 with an infectious isolate of B. abortus (Strain 2308). Studies of the IgG2 antibodies response indicated an absolute correlation between anti-Brucella IgG2 levels and infection of the animal. All animals showing reciprocal titers of greater than or equal to 3000 (16 of 45 tested) were found to be positive for the challenge organism at slaughter. Animals with reciprocal IgG2 titers less than or equal to 1000 (29 of 45 tested) were found to be negative for the challenge organism at the time of slaughter. The predictive value of IgG2 antibody levels for infection held for animals in all three groups and consequently this suggests that monitoring of specific IgG2 anti-Brucella antibody levels may be of value in detection of Brucella-infected cattle.     

Vertical transmission of channel catfish virus

Channel catfish broodfish were examined nondestructively for the presence of channel catfish virus (CCV), using a nucleic acid-probing technique. A dot blot assay was tested and shown to be accurate and rapid in the diagnosis of CCV. Two CCV-positive fish were successfully mated, and fertilized eggs were collected. Offspring that hatched were tested and were shown to have CCV. This result indicated vertical transmission of CCV, a herpesvirus.