Sweat tests to diagnose cystic fibrosis in adults.

Twenty five patients with cystic fibrosis and 25 controls were studied to define a sweat sodium concentration in adults that could be taken as diagnostic of cystic fibrosis. Some of the controls had a sweat sodium concentration of over 50 mmol(mEq)/l, and thus cystic fibrosis should be diagnosed in an adult only when two measurements of sweat sodium concentration are above 70 mmol/l. In cases in which the sweat sodium concentration was borderline a suppression test using fludrocortisone improved the accuracy of diagnosis; this test entails recording the lowest concentration reached after administration of the drug. A scatter diagram of the baseline sweat sodium concentrations plotted against the lowest concentration attained after suppression with fludrocortisone may aid the diagnosis further.     

Glucocorticoid modulation of lymphokine-induced macrophage proliferation

The ability of glucocorticoids to modify lymphokine-induced macrophage proliferation, an in vitro correlate of cellular immunity in the guinea pig, was investigated. Lymphocyte production of macrophage mitogenic factor (MMF) was decreased in the presence of physiological concentrations of glucocorticoids. Inhibition was concentration dependent (IC₅₀ of triamcinolone acetonide (TA): 2 × 10^?9M), glucocorticoid specific, and reversed by cortexolone. In contrast, pharmacological concentrations of glucocorticoids were necessary to inhibit macrophage proliferation induced by suboptimal dilutions of MMF. This inhibition was concentration dependent (IC₅₀ of TA: 4 × 10^?7M), glucocorticoid specific, and reversed by cortexolone. At supraoptimal dilutions of MMF, glucocorticoids caused a twofold potentiation of MMF-induced macrophage proliferation. Potentiation was concentration dependent (EC₅₀ of TA: 3 × 10^?8M), glucocorticoid specific, reversed by glucocorticoid antagonists, and occurred in the presence of indomethacin. Thus, glucocorticoids regulate both the initiation and effector phases of this in vitro model of delayed hypersensitivity. However, the results indicate that the major mechanism of glucocorticoid-mediated anti-inflammatory action occurs at the level of the MMF-producing lymphocyte rather than at the effector macrophage, as MMF-induced proliferation is likely controlled by opposing glucocorticoid-sensitive mechanisms.     

IL-1 gene expression in lymphoid tissues

We examined the expression of IL-1 mRNA in vivo by in situ hybridization. RNA probes for murine IL-1 alpha and IL-1 beta were used to detect IL-1 mRNA in frozen sections of spleen, lymph node, and thymus of mice injected with Salmonella typhi LPS or SRBC. No IL-1 was detected in lymphoid tissues from un-injected mice. This lack of expression correlated with the absence of IL-1 biologic activity. However, after LPS injection, IL-1 alpha and beta mRNA expression was found in macrophages of the red pulp and marginal zone of the spleen. The periarteriolar lymphoid sheath contained cells that only expressed IL-1 beta mRNA. These cells were not lymphocytes and did not stain with the macrophage marker F4/80. A similar cellular response was found after SRBC injection. Scattered macrophages in lymph nodes and thymus were positive, but only after LPS or SRBC injection. The spleens of mice injected with LPS had megakaryocytes containing IL-1 mRNA.     

Continuous culture system for production of biopolymer levan using erwinia herbicola

The optimal production of the fructan biopolymer levan by the bacterium Erwinia herbicola was investigated, including variations in nitrogen, carbon and phosphorous sources, pH, incubation time, culture yields up to 19% by weight produced based on conversion of sucrose as the carbon source when grown in a continuous culture system and processed by tangential flow filtration. Product identity was confirmed with gas chromatography (GC) and (13)C nuclear magnetic resonance (NMR). Gel permeation chromatography (GPC) and low-angle laser light scattering (LALLS) determination of the molecular weight of the product showed a significant difference in molecular weight values dependent on the method of analysis. Analysis by GPC resulted in molecular weight one order of magnitude lower than LALLS independent of sample, underscoring the unusual nature of this biopolymer.     

Prevention of fungal colonization and digestion of cellulose by the addition of methylcellulose

When the attachment of cellulolytic rumen fungi to cellulose is blocked by the addition of methylcellulose, cellulose digestion is entirely inhibited. Even after these fungi have colonized and penetrated the cellulosic fibers of filter paper, the addition of methylcellulose effectively halts cellulose digestion. This effect of methylcellulose is accompanied by the complete inhibition of fungal attachment to cellulose fibers; the addition of methylcellulose does not affect the growth of these organisms on soluble substrates. We conclude that fungal cellulose digestion, like bacterial cellulose digestion, requires the spatial juxtaposition of the cellulolytic organism and its insoluble substrate. The simultaneous inhibition of both attachment and digestion by the same inhibitor suggests that these two processes are functionally linked in the fungi.     

Temporal and spatial differences in glycosaminoglycan synthesis by fetal lung fibroblasts

In studies of the ontogeny of fibroblast-epithelial interactions during late fetal lung rat lung development, we have identified two subpopulations of fibroblasts which differed in their ability to promote epithelial cell proliferation or differentiation. As glycosaminoglycans (GAGs) have been implicated in the regulation of these processes we have tested whether the two fibroblast populations synthesize different GAGs and whether the GAG pattern changes with development. Fibroblasts incorporate more [3H]glucosamine and Na2 35SO4 into GAGs than epithelial cells. Both cell types deposited a significant amount of newly synthesized GAGs in the cell-matrix layer. GAGs were lost faster from the cell-matrix layer of fibroblasts (t1/2 = 12 h) than from that of epithelial cells (t1/2 = 48 h). Total GAG synthesis by fibroblasts did not change with advancing gestation, but synthesis of sulfated GAGs by epithelial cells declined with advancing gestation. Independent of gestational age epithelial cells synthesized predominantly heparan sulfate. Depending on their proximity to the epithelium, fibroblasts differed in their production of GAGs. Fibroblasts in close proximity to the epithelium mainly produced and secreted hyaluronan. More distant fibroblasts, from the pseudoglandular stage of lung development synthesized primarily heparan sulfate and chondroitin sulfate. This same population of fibroblasts from the canalicular stage of lung development, produced more hyaluronan. As the shift to hyaluronan occurs with the thinning of the alveolar septal wall, this finding suggests that developmentally regulated GAG production by fibroblasts may facilitate epithelial-fibroblast interaction, thus influencing fetal lung growth and differentiation.     

Stage-specific cuticular proteins of Ostertagia circumcincta and Ostertagia ostertagi

In this study we have shown that NHS-biotin and I¹²⁵-streptavidin can detect cuticular polypeptides of Ostertagia spp. The labelled polypeptide profile of intact nematodes is simple compared to the profile obtained by labelling homogenates. None of the major internal polypeptides are labelled and the subset of proteins labelled in intact nematodes appears to be mainly surface associated. The results presented here demonstrate that NHS-biotin may be used as a reagent for the analysis of surface polypeptides. The surface polypeptide profiles of the five major developmental stages (L1, L2, L3, L4 and adult) of Ostertagia circumcincta show a series of stage-specific molecules with no polypeptides common to all stages, indicating that the cuticle is a dynamic structure which changes throughout the life cycle. Similarity comparison of Ostertagia ostertagi L3 and L4 stage surface profiles showed that each stage is clearly distinct; comparison of these stages between the two species shows an overall similarity.     

Wood excavations of three species of subterranean termites

We compared the feeding excavations on wood blocks of three species of subterranean termites, Coptotermes formosanus Shiraki, Reticulitermes flavipes (Kollar), and R. virginicus (Banks). Feeding rate followed the order C. formosanus > R. flavipes > R. virginicus. Wood surface area (mm²) exposed per unit feeding was higher for C. formosanus and R. flavipes than for R. virginicus. This was caused by the tendency of C. formosanus and R. flavipes to make internally penetrating tunnels, thereby increasing surface area, whereas R. virginicus made trough- and bowl-like depressions on the outside of blocks, sometimes decreasing the size of blocks outwardly without a corresponding high increase in surface area typical with the tunnels of the other species. Consequently, wood surface area was sometimes reduced, rather than increased as a result of feeding by R. virginicus. Different patterns of wood excavation suggest that these termites have divergent roles in wood decay processes.

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Résumé Les organismes pionniers qui modifient le bois et le rendent acceptable par les insectes qui le perforent sont généralement des champignons du bois pourri. Cependant, une fois que les termites ou autres insectes perforant le bois ont pénétré, leurs galeries favorisent les bactéries fixatrices d'azote, permettent l'invasion d'autres organismes décomposeurs, et de ce fait régularisent la décomposition du bois (Ausmus, 1977). L'exposition de la surface à l'intérieur des perforations jouant un rôle très important dans le processus de pourrissement, il est souhaitable de pouvoir quantifier la surface des galeries dues à l'alimentation des termites. Une courbe type permettant de prédire l'aire de la surface perforée a été construite en perçant 109 morceaux de bois de trous cylindriques de différents diamètres, en calculant l'aire de la surface des morceaux de bois, en appliquant et pesant une couche de vernis pour bois au polyuréthane, et en divisant la masse de polyuréthane par l'aire de la surface. Le modèle prédictif qui en découle est: Y=0,01443×-3,51825 (P=0,0001; r=0,68), y étant la masse de polyuréthane (en g) et x la surface (en mm²) du morceau de bois. En traitant de la même façon au polyuréthane les morceaux de bois perforés par les termites, nous pourrions déduire leur surface.Une expérience a été effectuée avec 3 espèces de rhinotermitides,- Coptotermes formosanus Shiraki, Reticulitermes flavipes (Kollar) et R. virginicus (Banks). Des groupes de chaque espèce se sont alimentés pendant 11 ou 12 jours sur des morceaux de bois non contaminés par des champignons. Nous avons déterminé la survie, la consommation, la modification de la surface du morceau de bois (par utilisation du modèle prédictif) et le changement de surface par terminte.La survie est la même, mais la consommation est dans l'ordre suivant: C. formosanus > R. flavipes > R. virginicus. L'aire de la surface exposée par unité d'alimentation était plus élevée pour C. formosanus et R. flavipes que pour R. virginicus (Tab. 1). Ceci est dû à la tendance de C. formosanus et R. flavipes de creuser des galeries vers l'intérieur, tandis que R. virginicus fait des cuvettes à la surface du bois. Les attaques superficielles de R. virginicus réduisent parfois le volume du morceau de bois sans accroître proportionnellement la surface comme le font les espèces creusant des galeries. Ainsi, avec R. virginicus la surface peut être réduite au lieu d'augmenter. Des différences entre colonies s'observent avec toutes les variables (Tab. 2).Nos résultats suggèrent que C. formosanus et R. flavipes contribuent plus que R. virginicus à exposer le bois aux autres organismes décomposeurs. Cependant, ces résultats peuvent être modifiés par un conditionnement préalable du bois par des champignons.

     

Identification of bacterial chemoattractants for oyster (Crassostrea virginica) hemocytes

The cytoplasmic and cell wall components of the Gram-positive bacterium Bacillus megaterium and the cytoplasmic and cell envelope components of the Gram-negative bacterium Escherichia coli were assayed for chemotactic activity for the hemocytes of Crassostrea virginica. The cellular components were separated by differential centrifugation and gel filtration was used to determine the approximate molecular weights of the chemoattractant molecules. Active fractions were assayed for glycoproteins and lipoproteins. As a result, it is known that hemocytes are chemotactically attracted to proteins of approximately 10,000 daltons which are associated with the cell wall of B. megaterium and the cell envelope of E. coli.