A model of T-cell unresponsiveness using the male-specific antigen, H-Y

Granuloma formation in schistosomiasis japonica differs in several respects from those observed in Schistosoma mansoni infections. We have utilized the lung granuloma model in mice sensitized with subcutaneous injection of Schistosoma japonicum eggs to study the kinetics and mechanisms of this response. Animals injected subcutaneously with a range of 50–50,000 S. japonicum eggs elicited a significant pulmonary granulomatous response around ova subsequently injected intravenously. The pulmonary granulomas were formed of macrophages, lymphocytes, and eosinophils. Both antithymocyte globulin and antieosinophil sera reduced significantly the size of the granulomas and depleted the corresponding cell. Nude athymic mice developed markedly reduced pulmonary granulomas as did mice treated with niridazole or hydrocortisone. Sensitization to the egg antigens was demonstrable as both immediate and arthus-type footpad responses. Our data show that cell-mediated pulmonary granulomas can form around S. japonicum eggs in animals previously sensitized by the subcutaneous route. This model may provide further insights into the pathogenesis of S. japonicum granuloma.     

Histochemical localization of glycosidases in dog epididymis

Synopsis The histochemical localization of five glycosidases was studied in the epididymis of mature dogs. -Galactosidase showed a distinct to strong reaction in the epithelium of the ductuli efferentes and throughout the whole length of the ductus epididymidis. -N-Acetylglucosaminidase reactivity was weak in the initial segment, but increased significantly in the middle and terminal segment. The maximum -glucuronidase activity was found in the ductuli efferentes and in the initial segment. The -mannosidase reaction was weak in all segments except the middle segment where a distinct activity was seen. With the method employed, no -fucosidase activity could be detected. The physiological role of the glycosidases in the epididymis is discussed briefly.     

Cell surface lipids and adhesion. III. The effects on cell adhesion of changes in plasmalemmal lipids.

The two preceding papers of this series suggest that the state of the plasmalemmal lipids affects cell adhesion. Plasmalemmal composition was altered by the experimental incorporation of fatty acids into R1 and R2 positions in the phosphatidyl components of the cell surface. In this paper we report that: (1) If the incorporation is of long chain length fatty acids (saturated) cell adhesion rises. (2) If the incorporation is of unsaturated fatty acids cell adhesion falls as the unsaturation increases. (3) Incorporation has to be extensive to produce a large change in adhesion. (4) Changes in adhesion parallel the plasmalemmal incorporation but do not follow the total cell incorporation. Item (4) argues that it is plasmalemmal and not other membrane lipids that are involved in cell adhesion. Item (3) suggests that bulk membrane properties and not some very specific grouping are involved in the effects of lipids on adhesion. The similar extents of incorporation of the various different fatty acids and the negligible amounts of lysophospholipids in the membranes of cells that have incorporated fatty acids argue that the effects are not due to differential accumulations of these lysolipids when incubations are done with different fatty acids. The changes in adhesion cannot be accounted for by changes in surface charge density since the electrophoretic mobility of the cells is unchanged by these incubations. It is suggested that these effects on adhesion due to changes in plasmalemmal lipids can be explained either in terms of the action of intermembrane van der Waals--London (electrodynamic) forces in cell adhesion or of changes in surface fluidity. These alternatives are discussed.     

X-ray microanalysis of zinc and calcium in ultrathin sections of human sperm cells using the pyroantimonate technique.

X-ray microanalysis of pyroantimonate-fixed sperm cells indicates the retention of calcium and zinc subcellularly in similar proportions to air dried cells. The ultrastructure is well preserved and is corelated with the analysis. Sodium, potassium and chlorine are all removed during the fixation. CAlcium and zinc are found present intracellularly both in association with and independent of antimonate precipitation. There thus appears to be a varying degree of binding of those elements subcellularly, precipitation occurring where binding is reduced.     

Large‐scale patterns of seed removal by small mammals differ between areas of low‐ versus high‐wolf occupancy

Because most tree species recruit from seeds, seed predation by small‐mammal granivores may be important for determining plant distribution and regeneration in forests. Despite the importance of seed predation, large‐scale patterns of small‐mammal granivory are often highly variable and thus difficult to predict. We hypothesize distributions of apex predators can create large‐scale variation in the distribution and abundance of mesopredators that consume small mammals, creating predictable areas of high and low granivory. For example, because gray wolf (Canis lupus) territories are characterized by relatively less use by coyotes (C. latrans) and greater use by foxes (Vulpes vulpes, Urocyon cinereoargentus) that consume a greater proportion of small mammals, wolf territories may be areas of reduced small‐mammal granivory. Using large‐scale, multiyear field trials at 22 sites with high‐ and low‐wolf occupancy in northern Wisconsin, we evaluated whether removal of seeds of four tree species was lower in wolf territories. Consistent with the hypothesized consequences of wolf occupancy, seed removal of three species was more than 25% lower in high‐wolf‐occupancy areas across 2 years and small‐mammal abundance was more than 40% lower in high‐wolf areas during one of two study years. These significant results, in conjunction with evidence of seed consumption in situ and the absence of significant habitat differences between high‐ and low‐wolf areas, suggest that top‐down effects of wolves on small‐mammal granivory and seed survival may occur. Understanding how interactions among carnivores create spatial patterns in interactions among lower trophic levels may allow for more accurate predictions of large‐scale patterns in seed survival and forest composition.     

Minimal Erythema Dose (MED) Testing

Ultraviolet radiation (UV) therapy is sometimes used as a treatment for various common skin conditions, including psoriasis, acne, and eczema. The dosage of UV light is prescribed according to an individual''s skin sensitivity. Thus, to establish the proper dosage of UV light to administer to a patient, the patient is sometimes screened to determine a minimal erythema dose (MED), which is the amount of UV radiation that will produce minimal erythema (sunburn or redness caused by engorgement of capillaries) of an individual''s skin within a few hours following exposure. This article describes how to conduct minimal erythema dose (MED) testing. There is currently no easy way to determine an appropriate UV dose for clinical or research purposes without conducting formal MED testing, requiring observation hours after testing, or informal trial and error testing with the risks of under- or over-dosing. However, some alternative methods are discussed.     

Fibronectin conformation regulates the proangiogenic capability of tumor-associated adipogenic stromal cells

Background

Changes in fibronectin (Fn) matrix remodeling contribute to mammary tumor angiogenesis and are related to altered behavior of adipogenic stromal cells; yet, the underlying mechanisms remain unclear due in part to a lack of reductionist model systems that allow the inherent complexity of cell-derived extracellular matrices (ECMs) to be deciphered. In particular, breast cancer-associated adipogenic stromal cells not only enhance the composition, quantity, and rigidity of deposited Fn, but also partially unfold these matrices. However, the specific effect of Fn conformation on tumor angiogenesis is undefined.

Methods

Decellularized matrices and a conducting polymer device consisting of poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) were used to examine the effect of Fn conformation on the behavior of 3T3-L1 preadipocytes. Changes in cell adhesion and proangiogenic capability were tested via cell counting and by quantification of vascular endothelial growth factor (VEGF) secretion, respectively. Integrin-blocking antibodies were utilized to examine varied integrin specificity as a potential mechanism.

Results

Our findings suggest that tumor-associated partial unfolding of Fn decreases adhesion while enhancing VEGF secretion by breast cancer-associated adipogenic precursor cells, and that altered integrin specificity may underlie these changes.

Conclusions and general significance

These results not only have important implications for our understanding of tumorigenesis, but also enhance knowledge of cell-ECM interactions that may be harnessed for other applications including advanced tissue engineering approaches. This article is part of a Special Issue entitled Organic Bioelectronics — Novel Applications in Biomedicine.