Farm-scale production of fuel ethanol and wet grain from corn in a batch process

The batch production of fuel grade ethanol and distillers' wet grain (wet solids) in a farm-scale process (1240-15,580 L/batch) is described. The employs yeast fermentation of amylase-treated corn mash and a two-stage distillation. Primary emphasis in this study was on the cooking, fermentation, and centrifugation steps. Without recycling, fermentation of the mash yield beers with 10.0-10.5% ethanol. Recycling of stillage supernatant at full, 75, or 50% strengths produced enriched mashes that after 48-h fermentation yielded beers with 5-;14% more ethanol. Recycling twice with full-strength supernatant at pH 7.0 increased the ethanol yield in the final beer 16.5%; however, the time to complete the final fermentation was extended form 48 to 72 h and salt buildup occurred. By recycling at pH 5.4, it was possible to avoid rapids salt buildup and obtain beers with 10.3-10.5% ethanol. Recycling resulted in increased levels of glucose, starch, crude protein, and fat in the beer and a reduced moisture content while the wet solids showed an increased starch content. Centrifugation after cooking or fermentation yield in the subsequently produced beer. Fermentation of a volume-resorted mash supernatant gave a beer with only 9.25% ethanol. Mash wet solids varied somewhat chemically from beer and stillage solids. An economic and energy balance analysis of various modes of plant operation are provided and plant considerations are suggested.     

Lectin-Like Constituents of Foods Which React with Components of Serum, Saliva, and Streptococcus mutans

Hot and cold aqueous extracts were prepared from 22 commonly ingested fruits, vegetables, and seeds. When tested by agar diffusion, extracts from 13 and 10 of the foods formed precipitin bands with samples of normal rabbit serum and human saliva, respectively; extracts from four of the foods also reacted with antigen extracts of strains of Streptococcus mutans. When added to rabbit antiserum, extracts from 18 of 21 foods tested inhibited reactivity with antigen extracts derived from S. mutans MT3. Extracts from 16 foods agglutinated whole S. mutans cells, whereas those from 10 foods agglutinated human erythrocytes of blood types A and B. The lectin-like activities of extracts which reacted with human saliva were studied further. Pretreatment of saliva-coated hydroxyapatite (S-HA) beads with extracts of bananas, coconuts, carrots, alfalfa, and sunflower seeds markedly reduced the subsequent adsorption of S. mutans MT3. Pretreatment of S-HA with banana extract also strongly inhibited adsorption of S. mutans H12 and S. sanguis C1, but it had little effect on attachment of Actinomyces naeslundii L13 or A. viscosus LY7. Absorption experiments indicated that the component(s) in banana extract responsible for inhibiting streptococcal adsorption to S-HA was identical to that which bound to human erythrocytes. The banana hemagglutinin exhibited highest activity between pH 7 and 8, and it was inhibited by high concentrations of glucosamine, galactosamine, and, to a lesser extent, mannosamine. Other sugars tested had no effect. The selective bacterial adsorption-inhibiting effect noted for banana extract was also observed in studies with purified lectins. Thus, pretreating S-HA with wheat germ agglutinin and concanavalin A inhibited adsorption of S. mutans MT3 cells, whereas peanut agglutinin, Ulex agglutinin, Dolichos agglutinin, and soybean agglutinin had little effect; none of these lectins affected attachment of A. viscosus LY7. Collectively, the observations suggest that many foods contain lectins which can interact with components of human saliva and S. mutans cells. Because of their potential to influence host-parasite interactions in the mouth and elsewhere in the gastrointestinal canal, these reactions warrant further study.     

A Prospective Nested Case-Control Study of Dengue in Infants: Rethinking and Refining the Antibody-Dependent Enhancement Dengue Hemorrhagic Fever Model

Background

Dengue hemorrhagic fever (DHF) is the severe and life-threatening syndrome that can develop after infection with any one of the four dengue virus (DENV) serotypes. DHF occurs almost exclusively in individuals with secondary heterologous DENV infections and infants with primary DENV infections born to dengue immune mothers. The widely accepted explanation for the pathogenesis of DHF in these settings, particularly during infancy, is antibody-dependent enhancement (ADE) of DENV infection.

Methods and Findings

We conducted a prospective nested case-control study of DENV infections during infancy. Clinical data and blood samples were collected from 4,441 mothers and infants in up to two pre-illness study visits, and surveillance was performed for symptomatic and inapparent DENV infections. Pre-illness plasma samples were used to measure the associations between maternally derived anti-DENV3 antibody-neutralizing and -enhancing capacities at the time of DENV3 infection and development of infant DHF.The study captured 60 infants with DENV infections across a wide spectrum of disease severity. DENV3 was the predominant serotype among the infants with symptomatic (35/40) and inapparent (15/20) DENV infections, and 59/60 infants had a primary DENV infection. The estimated in vitro anti-DENV3 neutralizing capacity at birth positively correlated with the age of symptomatic primary DENV3 illness in infants. At the time of symptomatic DENV3 infection, essentially all infants had low anti-DENV3 neutralizing activity (50% plaque reduction neutralizing titers [PRNT₅₀] ≤50) and measurable DENV3 ADE activity. The infants who developed DHF did not have significantly higher frequencies or levels of DENV3 ADE activity compared to symptomatic infants without DHF. A higher weight-for-age in the first 3 mo of life and at illness presentation was associated with a greater risk for DHF from a primary DENV infection during infancy.

Conclusions

This prospective nested case-control study of primarily DENV3 infections during infancy has shown that infants exhibit a full range of disease severity after primary DENV infections. The results support an initial in vivo protective role for maternally derived antibody, and suggest that a DENV3 PRNT₅₀ >50 is associated with protection from symptomatic DENV3 illness. We did not find a significant association between DENV3 ADE activity at illness onset and the development of DHF compared with less severe symptomatic illness. The results of this study should encourage rethinking or refinement of the current ADE pathogenesis model for infant DHF and stimulate new directions of research into mechanisms responsible for the development of DHF during infancy.

Trial registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00377754","term_id":"NCT00377754"}}NCT00377754 Please see later in the article for the Editors'' Summary     

Novel Immunohistochemical Techniques Using Discrete Signal Amplification Systems for Human Cutaneous Peripheral Nerve Fiber Imaging

Confocal imaging uses immunohistochemical binding of specific antibodies to visualize tissues, but technical obstacles limit more widespread use of this technique in the imaging of peripheral nerve tissue. These obstacles include same-species antibody cross-reactivity and weak fluorescent signals of individual and co-localized antigens. The aims of this study were to develop new immunohistochemical techniques for imaging of peripheral nerve fibers. Three-millimeter punch skin biopsies of healthy individuals were fixed, frozen, and cut into 50-µm sections. Tissues were stained with a variety of antibody combinations with two signal amplification systems, streptavidin-biotin-fluorochrome (sABC) and tyramide-horseradish peroxidase-fluorochrome (TSA), used simultaneously to augment immunohistochemical signals. The combination of the TSA and sABC amplification systems provided the first successful co-localization of sympathetic adrenergic and sympathetic cholinergic nerve fibers in cutaneous human sweat glands and vasomotor and pilomotor systems. Primary antibodies from the same species were amplified individually without cross-reactivity or elevated background interference. The confocal fluorescent signal-to-noise ratio increased, and image clarity improved. These modifications to signal amplification systems have the potential for widespread use in the study of human neural tissues.     

Binding selectivity ofStreptococcus pyogenes and M-protein to epithelial cells differs from that of lipoteichoic acid

The ability of M-protein-positive (M⁺) and M-protein-negative (M^–) strains (including an M^– mutant lacking the structural gene for M-protein) ofStreptococcus pyogenes to attach to human pharyngeal, buccal, and tongue epithelial cells was compared. We observed that M⁺ strains ofS. pyogenes attached in significantly higher numbers to human pharyngeal epithelial cells than to human buccal or tongue cells. M^– strains did not exhibit high-level binding to any type of epithelial cell. Also, the adhesion of an M⁺ and an M^– strain ofS. pyogenes was low to all types of rat epithelial cells tested. The apparent differences in the surface components between human pharyngeal and buccal epithelial cells were confirmed by studies utilizing radiolabeled lectins.Ulex europaeus lectin with a specificity for fucosyl residues, andTriticum vulgaris lectin with a specificity for N-acetyl glucosamine and N-acetyl neuraminic acid residues, bound in higher amounts to human pharyngeal cells than to buccal cells. Pretreatment of pharyngeal epithelial cells with microgram quantities of highly purified type 6 M-protein or miligram quantities of lipoteichoic acid (LTA) derived fromS. pyogenes decreased the subsequent attachment of the organism. However, the binding specificities of³H-LTA were different from those of intact streptococci;³H-LTA bound comparably to human pharyngeal, buccal, and tongue epithelial cells, and it bound in higher quantities to rat epithelial cells. Also, although the adsorption ofS. pyogenes cells to pharyngeal cells was inhibited by the presence of fucose and galactose, these sugars had little effect on the binding of³H-LTA to epithelial cells. In contrast, the high adhesion of M⁺ strains but not M^– mutants to pharyngeal cells suggested that M-protein may play an important role. This possibility was supported by the observation that³H-labeled purified type 6 M-protein bound in higher concentrations to human pharyngeal epithelial cells than to human buccal cells. Furthermore, human pharyngeal epithelial cells were estimated to contain larger numbers of binding sites for M-protein than buccal cells, whereas the affinity of M-protein was similar to both cell types. These adsorption parameters are similar to those previously established for intact streptococcal cells.     

Biological activity of parathyroid hormone antagonists substituted at position 13.

Lysine occupies position 13 in the parathyroid hormone (PTH) antagonist, [Nle8,18,Tyr34]bPTH(7-34)NH2. Acylation of the epsilon-amino group in lysine 13 by a hydrophobic moiety is well tolerated in terms of bioactivity: the analog [Nle8,18, D-Trp12,Lys 13 (epsilon-3-phenylpropanoyl),Tyr34]bPTH(7-34)NH2 is equivalent to the parent peptide in its affinity for PTH receptors and its ability to inhibit PTH-stimulated adenylate cyclase in both kidney- and bone-based assays. Truncation of this peptide by deletion of phenylalanyl7 with concomitant removal of the amino-terminal alpha-amino group yielded the analog desamino[Nle8,18,D-Trp12,Lys13 (epsilon-3-phenylpropanoyl),Tyr34]bPTH(8-34)NH2, an antagonist of high potency in vitro (Kb = 4 and 9 nM, Ki = 73 and 3.5 nM in kidney- and bone-based assays, respectively). Also this analog is potentially stable to aminopeptidases present in many biological systems.     

The structure of the central stalk in bovine F(1)-ATPase at 2.4 A resolution

The central stalk in ATP synthase, made of gamma, delta and epsilon subunits in the mitochondrial enzyme, is the key rotary element in the enzyme's catalytic mechanism. The gamma subunit penetrates the catalytic (alpha beta)(3) domain and protrudes beneath it, interacting with a ring of c subunits in the membrane that drives rotation of the stalk during ATP synthesis. In other crystals of F(1)-ATPase, the protrusion was disordered, but with crystals of F(1)-ATPase inhibited with dicyclohexylcarbodiimide, the complete structure was revealed. The delta and epsilon subunits interact with a Rossmann fold in the gamma subunit, forming a foot. In ATP synthase, this foot interacts with the c-ring and couples the transmembrane proton motive force to catalysis in the (alpha beta)(3) domain.     

Inheritance of resistance to neonatal E. coli diarrhoea in the pig: examination of the genetic system

Summary Evidence is presented that a dominant allele, S, is expressed as a receptor for K88 on the brushborder surface of the pig intestinal cell. The homozygous recessive (ss) lacks this receptor. The receptor enables K88 — positive coliforms to adhere to the gut of the piglet which they must do if they are to cause neonatal diarrhoea. The homozygous recessive is thus a disease resistant animal.A possible reason for the persistence of the dominant (susceptible) gene is given.