Multipotential retinal precursors give rise to all cell types seen in multilayered retina. The generation of differentiation and diversity of neuronal cell types is determined by both extrinsic regulatory signals and endogenous genetic programs. We have previously reported that cell commitment in human retinal precursor cells (SV-40T) can be modified in response to exogenous growth factors, basic fibroblast growth factor, and transforming growth factor alpha (bFGF and TGFalpha). We report in this study that nontransformed human retinal precursors differentiate into photoreceptors by a cell density-dependent mechanism, and the effects were potentiated by bFGF and TGFalpha alone or in combination. A larger proportion of multipotential precursors plated at a density of 1 x 10(4) cells/cm(2) differentiated into neurons (photoreceptors) compared to cells plated at 3-5 x 10(4)/cm(2) and 1 x 10(5) cells/cm(2) under serum-free conditions and the effects were amplified seven- to eightfold in response to growth factors. Basic fibroblast growth factor (bFGF) and TGFalpha can induce 90% of the cells to assume a photoreceptor phenotype at a lower cell density, compared to only 30 and 25% of the cells acquiring a photoreceptor phenotype at intermediate and higher cell densities. Furthermore, at a lower cell density, 60-70% of the cells incorporate Bromodeoxyuridine (Brdu), suggesting that cells in a cell cycle may make a commitment to a specific fate in response to neurotrophins. Neurons with a photoreceptor phenotype were positive for three different sets of antibodies for rods/cones. Cells also exhibited upregulation of other proteins such as a D4 receptor protein expressed in photoreceptors, protein kinase Calpha (PKCalpha) expressed in rod bipolars and blue cones, and some other neuronal cell types. This was also confirmed by Western blot analysis. Newly derived photoreceptors survive for a few days before significant cell death ensues under serum-free conditions. To summarize, differentiation in precursors is density dependent, and growth factors amplify the effects.

No abstract

The primary objective of food hygiene is to eliminate or reduce the risk of exposure to foodborne illness. Biological, chemical and/ or physical agents contaminating food may cause foodborne illness, but by far the most common causes are biological agents, with microorganisms constituting a major proportion. Although consumers express hygiene/microbiological safety concerns about public dining places/kitchens, a significant proportion of foodborne outbreaks actually occur in homes. The general public needs to get equipped with some fundamental knowledge about food hygiene/microbiological safety (FHMS) in typical household kitchens and some of these are presented in this concise review. Microorganisms may gain access to and contaminate food through various routes including the hands of individual(s) preparing the food, cooking utensils, water for cooking, among others. Given the ubiquity of microorganisms and various routes of contamination of food, one can safely say that it is extremely difficult, if not impossible, to achieve total purity in terms of food contamination. Therefore, food hygiene/ microbiological safety should target, not necessarily to totally eliminate microorganisms from food, but to prevent any continued proliferation and/or production of toxins in food. Understanding the food hygiene/microbiological safety concept(s) definitions can help to enhance the knowledge base of kitchen user(s) with respect to principles of foodborne diseases and food safety practices. In this concise review also, some common modes of microbial contamination in household kitchen as well as food safety practices will be discussed, to help educate the general public as well as reduce the incidence of foodborne illnesses within household kitchen contexts.

Fiberglass duct liners and fiberglass duct boards from eight buildings whose occupants complained of unacceptable or moldy odors in the air were found to be heavily colonized by fungi, particularly by AspergiUus versicolor. Unused fiberglass was found to be susceptible to fungal colonization in environmental chambers dependent upon relative humidity. No colonization was observed at relative humidities below 50%o.

No abstract

Introduction: Cryptosporidiosis is a common disease of children and immune-compromised persons. This study evaluated the diversity and distribution of Cryptosporidium species in diarrheal children and HIV-infected persons on highly active antiretroviral therapy (HAART) and those not on HAART. Methodology: A total of 394 fecal specimens were collected from patients attending clinics in Nsukka and Ebonyi, Nigeria. Detection and identification of Cryptosporidium species were conducted by PCR-RFLP of the small subunit (SSU) rRNA gene, whereas subtyping was done by sequence analysis of the 60 kDa glycoprotein (gp60) gene. Results: Twenty-five (6.3%) specimens yielded four Cryptosporidium species, including C. hominis, C. parvum, C. felis, and C. viatorum. C. hominis was the most dominant species with 48.0% occurrence and three identified subtype families: Ia (six specimens), Ib (three specimens), Ie (two specimens), and one un-subtyped species. C. parvum had 44.0% occurrence and two subtype families: IIc (eight specimens) and IIe (three specimens), while C. felis and C. viatorum each had 4.0% occurrence. There were significant differences in Cryptosporidium species distribution between age groups in children and HIV-infected persons, between suburban and urban areas, and between low and high CD4

Mobile tigecycline resistance (MTR) threatens the clinical efficacy of the salvage antibiotic, tigecycline (TIG) used in treating deadly infections in humans caused by superbugs (multidrug-, extensively drug-, and pandrug-resistant bacteria), including carbapenem- and colistin-resistant bacteria. Currently, non-mobile tet(X) and mobile plasmid-mediated transmissible tet(X) and resistance-nodulation-division (RND) efflux pump tmexCD-toprJ genes, conferring high-level TIG (HLT) resistance have been detected in humans, animals, and environmental ecosystems. Given the increasing rate of development and spread of plasmid-mediated resistance against the two last-resort antibiotics, colistin (COL) and TIG, there is a need to alert the global community on the emergence and spread of plasmid-mediated HLT resistance and the need for nations, especially developing countries, to increase their antimicrobial stewardship. Justifiably, MTR spread projects One Health ramifications and portends a monumental threat to global public and animal health, which could lead to outrageous health and economic impact due to limited options for therapy. To delve more into this very important subject matter, this current work will discuss why MTR is an emerging health catastrophe requiring urgent One Health global intervention, which has been constructed as follows: (a) antimicrobial activity of TIG; (b) mechanism of TIG resistance; (c) distribution, reservoirs, and traits of MTR gene-harboring isolates; (d) causes of MTR development; (e) possible MTR gene transfer mode and One Health implication; and (f) MTR spread and mitigating strategies.

The purpose of this study was to determine if immortalized human retinal precursor cells could serve as a model to investigate cues that modulate cell fate and differentiation. We investigated the effects of a variety of growth factors broadly but specifically tested the effects of basic fibroblast growth factor (bFGF) and transforming growth factor (TGF)a in retinal cell differentiation and commitment. To determine the role of exogenously added growth factors in a human retinal precursor cell line (KGLDMSM), established from a first-trimester retina, cells were adapted to grow in a defined medium and exposed to a variety of trophic factors (epidermal growth factor [EGF], neuron growth factor [NGF], TGFalpha, TGFbeta, acidic FGF, and bFGF). Dose-response curves were developed to arrive at optimal concentrations. The neurotrophic potential of growth factors was determined by 3H-thymidine incorporation and bromodeoxyuridine (BrdU) labeling. The identity of the emerging neuronal phenotypes were determined by phase-contrast microscopy, immunolabeling for the neuron-specific antigens neurofilament protein (NF) and neuron-specific enolases (NSE), and photoreceptor-specific antigens (Rho1D4, 7G6) using immunocytochemistry and Western blot analysis. To identify some of the early response genes (c-fos, c-myc) expressed in response to growth factors, Northern blot analysis was performed. Almost all of the factors tested increased the total number of cells with a neuronal phenotype. Potency of growth factors to generate neurons was TGFalpha > bFGF > EGF > NGF. Both TGFalpha and bFGF, alone or in combination, increased the total number of neurons. Most of the neurons generated were photoreceptors, as depicted by the polarized phenotype, expression of photoreceptor-specific antigens, and processes resembling rudimentary outer segments. The increase in photoreceptor-like neurons is possibly attributable to an increase in numbers rather than greater survival. Additionally, the majority of the photoreceptors generated labeled with BrdU and for photoreceptor-specific antigens, suggesting that an inductive effect of bFGF and TGFalpha could occur in the cell cycle or shortly thereafter. Both bFGF and TGFalpha induced the expression of the early response gene c-fos while not altering the expression of c-actin or c-myc. The emergence of a photoreceptor phenotype was confirmed by both immunocytochemistry and Western blot analysis. The immortalized retinal precursor cell line could prove valuable in determining the role of exogenously added growth factors in retinal development and differentiation. Both bFGF and TGFalpha enhance the photoreceptor phenotype in medium-density cultures under conditions of defined medium. The same was confirmed by phase-contrast microscopy, immunocytochemistry, and Western blot analysis. Furthermore, cell fate determination in cultured precursor cells could occur during the late part of the cell cycle or shortly after completion of cell division. The effects of TGFalpha and bFGF seem to be slightly additiv...