Pulmonary microcirculatory kinetics of neutrophils deficient in leukocyte adhesion-promoting glycoproteins

The mechanism that causes neutrophils to sequester in the pulmonary circulation is unknown. Because the CD11/CD18 glycoprotein family on the surface membrane of neutrophils participates in many adhesive interactions with the endothelium, we investigated the role of these proteins in the intravascular sequestration of pulmonary neutrophils. Neutrophils were isolated from normal dogs and from the only living dog known to have leukocyte adhesion deficiency disease, an inherited deficiency of the CD11/CD18 adhesion family. The neutrophils were labeled with fluorescein dye, injected into normal recipient dogs, and their passage through the pulmonary microcirculation was recorded by in vivo videofluorescence microscopy through a transparent thoracic window. Transit times for normal and deficient neutrophils were similar over a wide range of hemo-dynamic conditions. Activation by zymosan-activated plasma, which increases the surface membrane expression of CD11/CD18, prolonged the transit of normal neutrophils but did not alter the transit time of the deficient neutrophils. These results indicate that neutrophil CD11/CD18 adhesion-promoting glycoproteins are not involved in the normal pulmonary sequestration of neutrophils but have a significant role in the arrest of activated neutrophils in the pulmonary capillaries.     

A mannose-specific adherence mechanism in Lactobacillus plantarum conferring binding to the human colonic cell line HT-29.

Two Lactobacillus plantarum strains of human intestinal origin, strains 299 (= DSM 6595) and 299v (= DSM 9843), have proved to be efficient colonizers of the human intestine under experimental conditions. These strains and 17 other L. plantarum strains were tested for the ability to adhere to cells of the human colonic cell line HT-29.L.plantarum 299 and 299v and nine other L. plantarum strains, including all six strains that belong to the same genetic subgroup as L. plantarum 299 and 299v, adhered to HT-29 cells in a manner that could be inhibited by methyl-alpha-D-mannoside. The ability to adhere to HT-29 cells correlated with an ability to agglutinate cells of Saccharomyces cerevisiae and erythrocytes in a mannose-sensitive manner and with adherence to D-mannose-coated agarose beads. L. plantarum 299 and 299v adhered to freshly isolated human colonic and ileal enterocytes, but the binding was not significantly inhibited by methyl-alpha-D-mannoside. Periodate treatment of HT-29 cells abolished mannose-sensitive adherence, confirming that the cell-bound receptor was of carbohydrate nature. Proteinase K treatment of the bacteria also abolished adherence, indicating that the binding involved protein structures on the bacterial cell surface. Thus, a mannose-specific adhesin has been identified in L. plantarum; this adhesin could be involved in the ability to colonize the intestine.     

Responses to food web manipulation in a shallow waterfowl lake

The effects of fish stock reduction have been studies in 3 Dutch lakes (Lake Zwemlust, Lake Bleiswijkse Zoom and Lake Noorddiep) and 1 Danish lake (Lake Væng) during 4–5 years. A general response id described. The fish stock reduction led in general to a low fish stock, low chlorophyii-a, high transparency and high abunuance of macrophytes. Large Daphnia became abundant, but their density decreased, due to food limitation and predation by fish. The total nitrogen concentration became low due to N-uptake by macrophytes and enhanced denitrification. In Lake Bleiswijkse Zoom the water transparency deteriorated and the clear water state was not stable. The fish stock increased and the production of young fish in summer was high. lear water occurred only in spring. Large daphnids were absent in summer and the macrophytes decreased.In Lake Zwemlust, Lake Væng and Lake Noorddiep the water remained clear during the first five years. In summer of the sixth year (1992) transparency decreased in Lake Zwemlust (with high P-concentration of 1.0 mg P l^-1). Also in Lake Væng (with a low nutrient concentration of 0.15 mg P.^-1) a short term turbid stage (1.5 month) occurred in summer 1992 after a sudden collapse of the macrophytes. Deterioration of the water quality seems to start in summer and seems related to a collapse in macrophytes. At a low planktivorous fishstock (e.g. Lake Væng)thhe duration of the turbid state is shorter. than in presence of a high planktivorous fish biomass (e.g. Lake Zwemlust, and later years of Lake Bleiswijkse Zoom).     

Sackville Waterfowl Park,Sackville, New Brunswick,Canada. Baseline characterization,towards long-term monitoring

The Sackville Waterfowl Park, contains a 19 hectare shallow freshwater wetland created by reflooding a saltwater marsh that was drained three centuries ago. Its primary purpose is to provide wetland habitat and wildlife viewing opportunities to tourists and residents. This newly created, eutrophic wetland supports high densities of waterfowl, 2.1 and 3.3 brood ha^–1 in 1991 and 1992 respectively. It is hoped that long term monitoring of the Park's waterfowl population and wetland habitat will contribute to a better understanding of factors controlling breeding waterfowl populations.     

Neutralization sensitivity of human immunodeficiency virus type 1 is determined in part by the cell in which the virus is propagated.

Neutralizing antibody responses to human immunodeficiency virus type 1 (HIV-1) vary widely and have not been reproducibly associated with prognosis or disease progression. We have found that both low-passage clinical isolates and laboratory-adapted strains of HIV-1 have different sensitivities to neutralization by the same antiserum, depending on the host cell in which the viral stock is prepared. One such isolate (VL069) grown in H9 cells was neutralized by 20 human sera at a geometric mean titer of 1:2,047; this same isolate prepared in peripheral blood mononuclear cell (PBMC) culture was neutralized at a mean titer of < 1:10 by the same sera. Adsorption and mixing experiments indicated that neither antibody to H9 cell components nor blocking by excess viral antigen was responsible for the differences observed. This host cell effect is rapidly reversible upon passage of the virus from PBMCs to H9 cells and back into PBMCs. In contrast, the neutralization characteristics remained remarkably stable over extended culture in PBMCs. Two laboratory strains and five clinical isolates were evaluated in expanded studies of this phenomenon. While the neutralization characteristics of most of the strains studied were affected by the host cell in which the strain was propagated, two of the strains (one clinical isolate and one laboratory strain) appeared antigenically unaffected by their cell of origin. Host cell effect was also evident in neutralization by monoclonal antibodies directed against the CD4-binding region and the V2, V3, and gp41 regions. Possible mechanisms for this host cell effect include (i) mutation during passaging; (ii) selection in different host cells of different subpopulations of the (uncloned) viral stock; and (iii) cell-specific posttranslational modifications. To explore these possibilities, the V3 through V5 region of gp120 was sequenced in preparations made by passing VL069 into H9 cells and into PBMCs; HIVMN grown in CEM-SS cells and in PBMCs was also sequenced. In both cases, a few amino acid changes outside the V3 region were found. Studies are currently under way to assess the significance of these changes.     

Immature mouse uterine tissue in organ culture: Estrogen-induced growth,morphology and biochemical parameters

Summary Although estrogens have been shown to stimulate a variety of morphologic and biochemical changes in the uterus in vivo, no clear consistent demonstration of similar responses in vitro have been made; thus, a defined organ culture system using the immature mouse uterus was established to study the possibility of demonstrating estrogenic responses in vitro. Uterine tissue from immature outbred mice (17 to 24 days of age) were cut crosswise in 1-mm³ coins and cultured in a defined medium in the absence of serum, phenol red, or growth factor supplements. Diethylstilbestrol (DES), a synthetic estrogen, was added to the media at doses ranging from 1 to 100 ng/ml. The effect of DES on uterine cell proliferation was assessed by morphologic changes in uterine epithelial and stromal cells, increase in number of epithelial cells per unit basement membrane, increase in height of luminal epithelial cells, and [³H]thymidine incorporation. Functional changes were determined by measuring the amounts of the estrogen-inducible uterine protein, lactoferrin, that was localized in the epithelial cells and secreted into the media, and the localization of the estrogen receptor in the cultured tissues. Results indicate that under the described conditions of culture, estrogens like DES can induce morphologic and biochemical responses in the uterus that are similar to those seen in vivo. This organ culture system will aid in the investigation of various mechanisms involved in the hormonal regulation of growth and differentiation of estrogen target tissues.     

Evidence that the putative compatible solute 5-dimethylsulfoniopentanoate is an extraction artifact.

A novel gas chromatography-mass spectrometry method for analyzing sulfonium compounds as their S-demethylated silyl derivatives has clarified the origin of 5-dimethylsulfoniopentanoate. This compound, previously reported from flowers of Diplotaxis tenuifolia (L.) DC. (Cruciferae), is generated from glucoerucin during treatment with hot 6 N HCl. Glucoerucin is the characteristic glucosinolate of D. tenuifolia.     

The ecosystem wilting point defines drought response and recovery of a Quercus-Carya forest

Soil and atmospheric droughts increasingly threaten plant survival and productivity around the world. Yet, conceptual gaps constrain our ability to predict ecosystem-scale drought impacts under climate change. Here, we introduce the ecosystem wilting point (Ψ_EWP), a property that integrates the drought response of an ecosystem's plant community across the soil–plant–atmosphere continuum. Specifically, Ψ_EWP defines a threshold below which the capacity of the root system to extract soil water and the ability of the leaves to maintain stomatal function are strongly diminished. We combined ecosystem flux and leaf water potential measurements to derive the Ψ_EWP of a Quercus-Carya forest from an “ecosystem pressure–volume (PV) curve,” which is analogous to the tissue-level technique. When community predawn leaf water potential (Ψ_pd) was above Ψ_EWP (=−2.0 MPa), the forest was highly responsive to environmental dynamics. When Ψ_pd fell below Ψ_EWP, the forest became insensitive to environmental variation and was a net source of carbon dioxide for nearly 2 months. Thus, Ψ_EWP is a threshold defining marked shifts in ecosystem functional state. Though there was rainfall-induced recovery of ecosystem gas exchange following soaking rains, a legacy of structural and physiological damage inhibited canopy photosynthetic capacity. Although over 16 growing seasons, only 10% of Ψ_pd observations fell below Ψ_EWP, the forest is commonly only 2–4 weeks of intense drought away from reaching Ψ_EWP, and thus highly reliant on frequent rainfall to replenish the soil water supply. We propose, based on a bottom-up analysis of root density profiles and soil moisture characteristic curves, that soil water acquisition capacity is the major determinant of Ψ_EWP, and species in an ecosystem require compatible leaf-level traits such as turgor loss point so that leaf wilting is coordinated with the inability to extract further water from the soil.     

The Human Mast Cell Chymase Gene (CMA1): Mapping to the Cathepsin G/Granzyme Gene Cluster and Lineage-Restricted Expression

Genes encoding T-cell-receptor α/δ chains, neutrophil cathepsin G, and lymphocyte CGL/granzymes are closely linked on chromosomal band 14q11.2. The current work identifies the human mast cell chymase gene (CMA1) as the fourth protease in this cluster and maps the gene to within 150 kb of the cathepsin G gene. The gene order is centromere-T cell receptor α/δ-CGL-1/granzyme B-CGL-2/granzyme H-cathepsin G-chymase. Chymase and cathepsin G genes are shown to be cotranscribed in the human mast cell line HMC-1 and in U-937 cells. Other cells transcribe cathepsin G or CGL/granzyme genes, but not chymase genes, suggesting a capacity for independent regulation. Comparison of the 5′ flank of the chymase gene with those of cathepsin G and CGL/granzymes reveals little overall homology. Only short regions of the 5′ flanks of the human and murine chymase genes sequenced to date are similar, suggesting that they are more distantly related than human and rodent CGL-1/granzyme B, the flanks of which are highly homologous. The expression patterns and clustering of genes provide possible clues to the presence of locus control regions that orchestrate lineage-restricted expression of leukocyte and mast cell proteases.