Nature Abhors a Vacuum: Highly Diverse Mechanisms Enable Spoilage Fungi to Disperse,Survive, and Propagate in Commercially Processed and Preserved Foods

Fungal spoilage in processed foods remains a challenge for food manufacturers despite the increasing availability of diverse processing and formulation strategies used to control foodborne microorganisms. Physiological features of yeasts and molds contribute to their tolerance to thermal processing, acidity, desiccation, and oxygen and nutrient limitations. These features variably include growth form, cell wall structure, cytoplasmic composition, cell membrane‐bound proteins, and secretion of secondary metabolites. Collectively, these mechanisms contribute to the ability of fungi to disperse, survive, and propagate in highly restrictive food environments. The diversity of fungal growth and survival mechanisms has resulted in organisms adapted to nearly all food environments; although, only a small subset of fungi are particularly suited for spoilage of a given product. The relationship between the individual physiology and metabolic capabilities of a yeast or mold and the product's specific physicochemical attributes and processing history determines spoilage potential. Explicit characterization of the fungal features responsible for this extremotolerance contributes to more targeted and effective control strategies.     

The retrospectroscope: electrocorticography

Recording the electrical activity of the exposed brain, known as an electrocorticogram (ECoG), has had a long history. Multichannel recordings from the exposed brain cortex of conscious human patients as a diagnostic procedure to localize epileptic foci began in the early 1940s. Two centers, one at McGill University and the other at Harvard University launched this new field. Relatively unrecognized at that time were the severe requirements for recording microvolt signals in the electrically hostile environment of the operating room. Not only did the electrodes have to be electrically stable initially, but they had to be stable and noise-free after steam sterilization. In 1945, one of the authors (LAG) joined the staff of the Montreal Neurological institute and the Department of Electrical Engineering, both of McGill University, and became deeply involved with the development of ECoG equipment for permanent installation in Wilder Penfield's operating room. The design goal was that the ECoG and electrodes would function on command. Because it required less than one half hour to steam sterilize the electrodes, a surgical procedure could be scheduled at any time, providing the ECoG and electrodes would perform on command     

A common factor regulates both Th1- and Th2-specific cytokine gene expression

Murine T helper cell clones are classified into two distinct subsets, T helper 1 (Th1) and T helper 2 (Th2), on the basis of cytokine secretion patterns. Th1 clones produce interleukin-2 (IL-2), tumor necrosis factor-beta (TNF-beta) and interferon-gamma (IFN-gamma), while Th2 clones produce IL-4, IL-5, IL-6 and IL-10. These subsets differentially promote delayed-type hypersensitivity or antibody responses, respectively. The nuclear factor NF-AT is induced in Th1 clones stimulated through the T cell receptor-CD3 complex, and is required for IL-2 gene induction. The NF-AT complex consists of two components: NF-ATp, which pre-exists in the cytosol and whose appearance in the nucleus is induced by an increase of intracellular calcium, and a nuclear AP-1 component whose induction is dependent upon activation of protein kinase C (PKC). Here we report that the induction of the Th2-specific IL-4 gene in an activated Th2 clone involves an NF-AT complex that consists only of NF-ATp, and not the AP-1 component. On the basis of binding experiments we show that this 'AP-1-less' NF-AT complex is specific for the IL-4 promoter and does not reflect the inability of activated Th2 cells to induce the AP-1 component. We propose that NF-ATp is a common regulatory factor for both Th1 and Th2 cytokine genes, and that the involvement of PKC-dependent factors, such as AP-1, may help determine Th1-/Th2-specific patterns of gene expression.     

In vitro isolation and identification of human immunodeficiency virus (HIV) variants with reduced sensitivity to C-2 symmetrical inhibitors of HIV type 1 protease

Protease inhibitors are another class of compounds for treatment of human immunodeficiency virus (HIV)-caused disease. The emergence of resistance to the current anti-HIV drugs makes the determination of potential resistance to protease inhibitors imperative. Here we describe the isolation of an HIV type 1 (HIV-1) resistant to an HIV-protease inhibitor. Serial passage of HIV-1 (strain RF) in the presence of the inhibitor, [2-pyridylacetylisoleucylphenylalanyl-psi (CHOH)]2 (P9941), failed to yield a stock of virus with a resistance phenotype. However, variants of the virus with 6- to 8-fold reduced sensitivity to P9941 were selected by using a combination of plaque assay and endpoint titration. Genetic analysis and computer modeling of the variant proteases revealed a single change in the codon for amino acid 82 (Val-->Ala), which resulted in a protease with lower affinity and reduced sensitivity to this inhibitor and certain, but not all, related inhibitors.     

Improved success of living unrelated renal transplantation with cyclosporine immunosuppression

Kidney transplantation with a living unrelated donor was performed in 13 patients. The donors comprised 10 spouses, 2 brothers-in-law and 1 stranger. All donor-recipient pairs were red blood cell compatible with a negative T cell crossmatch. Five patients underwent transplantation before 1984 without cyclosporine immunosuppression; the 1-year patient and graft survival rates in this group were 40% and 20%, respectively. Eight patients have undergone transplantation since 1985 with cyclosporine immunosuppression. The 1-year patient and graft survival rates in this group were 100% and 88%, respectively (p = 0.03). Currently, 6 patients in the latter group have a well functioning graft with serum creatinine levels of 1.2 to 2.0 mg./dl. (mean 1.5 mg./dl.) and with followup of 1 to 6 years (mean 2.9 years). Excellent graft survival results can now be achieved with living unrelated donors and their expanded use can provide an important additional source of organs for transplantation.     

Adam-Gibbs Formulation of Enthalpy Relaxation Near the Glass Transition

The entropically based nonlinear Adam-Gibbs equation is discussed in the context of phenomenologies for nonlinear enthalpy relaxation within the glass transition temperature range. In many materials for which adequate data are available, the nonlinear Adam-Gibbs parameters are physically reasonable and agree with those obtained from linear relaxation data and thermodynamic extrapolations. Observed correlations between the traditional Tool-Narayanaswamy-Moynihan parameters are rationalized in terms of the Adam-Gibbs primary activation energy (Δμ) determining how close the kinetic glass transition temperature can get to the thermodynamic Kauzmann temperature. It is shown that increased nonlinearity in the glass transition temperature range is associated with greater fragility in the liquid/rubber state above T_g.