In vitro Cell Culture Model for Toxic Inhaled Chemical Testing

Cell cultures are indispensable to develop and study efficacy of therapeutic agents, prior to their use in animal models. We have the unique ability to model well differentiated human airway epithelium and heart muscle cells. This could be an invaluable tool to study the deleterious effects of toxic inhaled chemicals, such as chlorine, that can normally interact with the cell surfaces, and form various byproducts upon reacting with water, and limiting their effects in submerged cultures. Our model using well differentiated human airway epithelial cell cultures at air-liqiuid interface circumvents this limitation as well as provides an opportunity to evaluate critical mechanisms of toxicity of potential poisonous inhaled chemicals. We describe enhanced loss of membrane integrity, caspase release and death upon toxic inhaled chemical such as chlorine exposure. In this article, we propose methods to model chlorine exposure in mammalian heart and airway epithelial cells in culture and simple tests to evaluate its effect on these cell types.     

Interspecific patterns for egg and clutch sizes of African Bufonidae (Amphibia: Anura)

Little is known about reproductive trade-offs in African amphibians, but such data, particularly in the form of quantitative measurements, are a key for investigating life history evolution. Here we compile and analyze known data on African bufonids from published material and new data from preserved museum specimens, to investigate interspecific patterns of egg and clutch sizes variation. Our data is a composite of mixed sources, including ova data from dissected females and laid clutches from observations in the field. Our study shows that, as body size increases, clutch size increases but egg size decreases, and when correcting for body size, egg size is inversely correlated with clutch size. These parameter interactions however, are different for different reproductive modes. In free-swimming larval developing species, the same trends are recovered, but for lecithotrophic viviparous species no significant correlations could be recovered for clutch size and body size nor for the trade-off between clutch size and egg size, and egg size is positively related to body size. The egg size of Nimbaphrynoides occidentalis (Angel, 1943) is a clear outlier, which may be due to its matrotrophic viviparous reproduction. In addition, we observed no statistical difference between ova data collected from dissections and laid clutch data from field observations, which suggests that such a mixed dataset has utility in comparative analyses.     

Sensitive fluorescence in situ hybridization signal detection in maize using directly labeled probes produced by high concentration DNA polymerase nick translation

The signal produced by fluorescence in situ hybridization (FISH) often is inconsistent among cells and sensitivity is low. Small DNA targets on the chromatin are difficult to detect. We report here an improved nick translation procedure for Texas red and Alexa Fluor 488 direct labeling of FISH probes. Brighter probes can be obtained by adding excess DNA polymerase I. Using such probes, a 30 kb yeast transgene, and the rp1, rp3 and zein multigene clusters were clearly detected.     

Trophic ecology of East African caecilians (Amphibia: Gymnophiona), and their impact on forest soil invertebrates

Diets of the syntopic caecilian amphibians Boulengerula boulengeri and Scolecomorphus vittatus were studied from gut content analyses of 108 specimens collected from Nilo Forest Reserve, East Usambara Mountains, Tanzania. Head length and width relative to body length is greater in male B. boulengeri than in females, but no such dimorphism is apparent in S. vittatus . No differences, other than females consuming disproportionately more ants and invertebrate eggs and fewer termites than males, occur in the diets of B. boulengeri . The gut contents of S. vittatus are dominated by large, surface-active earthworms, in contrast to those of B. boulengeri which contained smaller, endogeic earthworms and a much greater number and diversity of soil arthropods (particularly termites, ants and Diptera larvae). These dietary characteristics underline differences in microhabitat use between these caecilian species and thus corroborate a previously proposed hypothesis of niche separation. The ecological impact of caecilians and other limbless endogeic vertebrates is little studied and poorly known. Approximations based on current knowledge are not clear, but are interpreted as indicating that predation by caecilians is unlikely to be among the most important factors influencing population densities of soil-dwelling termites and perhaps also ants: two groups recognized as soil ecosystem engineers.     

Human alveolar macrophage fibronectin: synthesis, secretion, and ultrastructural localization during gelatin-coated latex particle binding

Human pulmonary alveolar macrophages synthesized and secreted several characteristic high molecular weight proteins for at least 7 d in vitro. Immunoprecipitates of medium and cell lysates from metabolically labeled cultures with specific anti-human plasma fibronectin IgG contained one major labeled polypeptide of molecular weight 440,000 (unreduced) or 220,000 (reduced). An identical polypeptide in conditioned medium from radiolabeled macrophages bound specifically to gelatin-Sepharose, demonstrating that alveolar macrophages synthesized and secreted a molecule immunologically and functionally similar to fibronectin. Fibronectin was the major newly synthesized and secreted polypeptide of freshly harvested alveolar macrophages. Pulse-chase experiments revealed that newly synthesized fibronectin was rapidly secreted into medium, approximately 50 percent appearing by 1 h and 80 percent by 8 h. Immunoperoxidase staining using antifibronectin F(ab’)(2)-peroxidase conjugates revealed the majority of immunoreactive fibronectin to be intracellular, localized to endoplasmic reticulum and Golgi apparatus. No extracellular matrix fibronectin was visualized, and cell surface staining was rarely seen, usually appearing only at sites where cells were closely apposed and not at sites of macrophage-substrate attachment. Similar immunostaining of fibroblast cultures revealed cell surface-associated fibrillar fibronectin. Ultrastructural localization of fibronectin during binding and phagocytosis of gelatin-coated and plain latex particles revealed fibronectin only on gelatin-latex beads and at their cell binding sites. Neigher plain latex beads nor their cell membrane binding sites stained for fibronectin. These results demonstrate that fibronectin is a major product of human alveolar macrophages, is rapidly secreted, and is localized at cell membrane binding sites for gelatin-coated particles. In view of the known binding properties of fibronectin, it may serve as an endogenous opsonic factor promoting the binding of staphylococcus, denatured collagen, fibrin, or other macromolecules to macrophages in the lower respiratory tract.     

Prenatal screening for hemoglobinopathies. III. Applicability of the health belief model.

A comprehensive prenatal hemoglobinopathy screening program in Rochester, NY, has been described in a preceding paper in this issue of the Journal. A woman identified as a carrier may face three decisions. The first is whether to accept the offer of counseling. The second is whether to have her partner tested. If her partner also tests positive, then the third decision is whether to accept the offer of prenatal diagnosis. This report analyzes factors affecting her decision, with special attention being given to factors invoked by the Health Belief Model. Factors predicting that a patient who we identified as a carrier would come for counseling included the following: patient had no prior knowledge that she is a carrier (P less than .001), a gestational age less than 18 wk (P less than .01), and Caucasian race (P less than .05). For sickle cell trait counselees and beta-thalassamia trait counselees, factors found to predict patient's intent to have partner tested were the following: a greater postcounseling knowledge of the disease (P less than .009), a lesser perceived burden of intervention (P less than .011), and belief that the partner is also a carrier (P less than .008). Also for sickle cell trait counselees and beta-thalassemia trait counselees, factors predicting that the partner actually will be tested were the following: living with the partner (P less than .001), gestational age at identification less than or equal to 18 wk (P less than .001), a lesser perceived burden of intervention (P less than .002), and a greater perceived seriousness of the disease (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)