Electron microscopic immunocytochemical localization of proline-rich proteins in normal mouse parotid salivary glands

Summary Rabbit polyclonal antibodies against isoproterenol-induced mouse proline-rich proteins (PRPs) were used to localize PRPs in the parotid salivary glands of normal adult BALB/c mice. The antibodies recognized both acidic-type and basic-type PRPs. Immunoblotting experiments revealed that the glands contained an acidic-type and a basic-type PRP. Parotid gland tissue was fixed with Karnosky's fixative and embedded in Lowicryl resin at low temperature. PRPs were localized at the electron microscope level using an indirect post-embedding staining technique with protein A-gold. The secretion granules of the acinar cells were strongly labelled. Pre-absorption of the antibody with purified acidic-type and basic-type PRPs indicated that the basic-type PRP is mainly located at the periphery of the granules but that the acidic-type PRP is more evenly distributed within the granules. Pre-absorption of the antibody with -amylase did not affect the staining pattern, suggesting minimal cross-reactivity. PRPs were also detected within the rough endoplasmic reticulum and the Golgi apparatus of acinar cells, within the granules of the proacinar cells and in the lumena of the ducts, but not within the intercalated or striated duct cell granules.     

Foliage plants for removing indoor air pollutants from energy-efficient homes

A sealed, Plexiglas chamber with temperature and humidity control and illuminated externally with wide spectrum grow lights was used to evaluate the ability of golden pothos (Scindapsus aureus), nephthytis (Syngonium podophyllum), and spider plant (Chlorophytum elatum var.vittatum) to effect the removal of formaldehyde from contaminated air at initial concentrations of 15–37 ppm. Under the conditions of this study, the spider plant proved most efficient by sorbing and/ or effecting the removal of up to 2.27 fig formaldehyde per cm² leaf surface area in 6 h of exposure. The immediate application of this new botanical air-purification system should be in energy-efficient homes that have a high risk of this organic concentrating in the air, due to outgassing of urea-formaldehyde foam insulation, particleboard, fabrics and various other synthetic materials.     

Deja vu: the evolution of feeding morphologies in the Carnivora

The fossil record of the order Carnivora extends back at least60 million years and documents a remarkable history of adaptiveradiation characterized by the repeated, independent evolutionof similar feeding morphologies in distinct clades. Within theorder, convergence is apparent in the iterative appearance ofa variety of ecomorphs, including cat-like, hyena-like, andwolf-like hypercarnivores, as well as a variety of less carnivorousforms, such as foxes, raccoons, and ursids. The iteration ofsimilar forms has multiple causes. First, there are a limitednumber of ways to ecologically partition the carnivore niche,and second, the material properties of animal tissues (muscle,skin, bone) have not changed over the Cenozoic. Consequently,similar craniodental adaptations for feeding on different proportionsof animal versus plant tissues evolve repeatedly. The extentof convergence in craniodental form can be striking, affectingskull proportions and overall shape, as well as dental morphology.The tendency to evolve highly convergent ecomorphs is most apparentamong feeding extremes, such as sabertooths and bone-crackerswhere performance requirements tend to be more acute. A surveyof the fossil record indicates that large hypercarnivores evolvefrequently, often in response to ecological opportunity affordedby the decline or extinction of previously dominant hypercarnivoroustaxa. While the evolution of large size and carnivory may befavored at the individual level, it can lead to a macroevolutionaryratchet, wherein dietary specialization and reduced populationdensities result in a greater vulnerability to extinction. Asa result of these opposing forces, the fossil record of Carnivorais dominated by successive clades of hypercarnivores that diversifyand decline, only to be replaced by new hypercarnivorous clades.This has produced a marvelous set of natural experiments inthe evolution of similar ecomorphs, each of which start fromphylogenetically and morphologically unique positions.     

Biomechanical consequences of rapid evolution in the polar bear lineage

The polar bear is the only living ursid with a fully carnivorous diet. Despite a number of well-documented craniodental adaptations for a diet of seal flesh and blubber, molecular and paleontological data indicate that this morphologically distinct species evolved less than a million years ago from the omnivorous brown bear. To better understand the evolution of this dietary specialization, we used phylogenetic tests to estimate the rate of morphological specialization in polar bears. We then used finite element analysis (FEA) to compare the limits of feeding performance in the polar bear skull to that of the phylogenetically and geographically close brown bear. Results indicate that extremely rapid evolution of semi-aquatic adaptations and dietary specialization in the polar bear lineage produced a cranial morphology that is weaker than that of brown bears and less suited to processing tough omnivorous or herbivorous diets. Our results suggest that continuation of current climate trends could affect polar bears by not only eliminating their primary food source, but also through competition with northward advancing, generalized brown populations for resources that they are ill-equipped to utilize.     

Pharmacokinetics and in vitro and in vivo anti-tumor response of an interleukin-2-human serum albumin fusion protein in mice

Purpose: Albuleukin fusion protein is a recombinant human interleukin-2 (rIL-2) genetically fused to recombinant human serum albumin (rHSA). The pharmacokinetics and pharmacologic activity of Albuleukin were examined in mice to determine whether the fusion protein had the immunomodulatory and anti-tumor properties of rIL-2 as well as a prolonged serum half-life due to the rHSA. Methods: The effect of Albuleukin on lymphocyte proliferation, IL-2 receptor binding, and release of IFN- from human NK cells were examined in vitro. For the pharmacokinetic analysis, Albuleukin and rIL-2 were administered intravenously (i.v.) and subcutaneously (s.c.) to BALB/c mice, both at a single dose of 500 g/kg. The anti-tumor properties of Albuleukin were evaluated in a Renca tumor model in BALB/c mice and in a metastatic liver model of B16F10 melanoma in C57B1/6 mice. In the Renca tumor model, BALB/c mice were dosed intraperitoneally (i.p.) and s.c. with Albuleukin on days 12, 14, 16, 19, 21, and 23 and i.p. with rIL-2 daily for two periods of 5 days (days 10–14 and 17–21). In the B16 melanoma model, C57B1/6 mice were dosed s.c. with rIL-2 twice daily or Albuleukin every 48 h for 14 days. Results: In vitro, Albuleukin induced the proliferation of primary human and mouse T cells and B cells and primary human NK cells, competed with rIL-2 for binding to the IL-2 receptors, and induced the production of IFN- from primary human NK cells. The s.c. bioavailability of Albuleukin was about 45% relative to the i.v. dose. Plasma half-life was prolonged and ranged from 6 to 8 h with Albuleukin, compared to 19–57 min with rIL-2. Total clearance of Albuleukin was about 50-fold slower than that of rIL-2 after i.v. dosing. In vivo, Albuleukin suppressed the growth of Renca tumors and induced a dense infiltration of CD4⁺ and CD8⁺ T cells. Both Albuleukin and rIL-2 significantly reduced the tumor burden in mice with hepatic B16F10 metastases. Albuleukin significantly reduced the incidence of residual macroscopic hepatic tumors, resulting in improved survival relative to controls and rIL-2. Conclusion: Results from these studies suggest that the therapeutic efficacy of rIL-2 is improved in mice by prolonging its in vivo half-life through genetic fusion to albumin. Albuleukin, the fusion protein, had pronounced anti-tumor effects in Renca and hepatic melanoma tumor models without an increase in mortality. On the basis of its preclinical effects, Albuleukin was brought to the clinic to assess its therapeutic benefit in a variety of cancers.