Molecular mechanisms of insulin resistance in chronic hepatitis C

It is now widely recognized that chronic hepatitis C (CHC) is associated with insulin resistance (IR) and type 2 diabetes, so can be considered a metabolic disease. IR is most strongly associated with hepatitis C virus (HCV) genotype 1, in contrast to hepatic steatosis, which is associated with genotype 3 infection. Apart from the well-described complications of diabetes, IR in CHC predicts faster progression to fibrosis and cirrhosis that may culminate in liver failure and hepatocellular carcinoma. More recently, it has been recognized that IR in CHC predicts a poor response to antiviral therapy. The molecular mechanisms for the association between IR and HCV infection are not well defined. This review will elaborate on the clinical associations between CHC and IR and summarize current knowledge regarding the molecular mechanisms that potentially mediate HCV-associated IR.

Hepatitis C virus core protein induces lipid droplet redistribution in a microtubule- and dynein-dependent manner

Attachment of hepatitis C virus (HCV) core protein to lipid droplets (LDs) is linked to release of infectious progeny from infected cells. Core progressively coats the entire LD surface from a unique site on the organelle, and this process coincides with LD aggregation around the nucleus. We demonstrate that LD redistribution requires only core protein and is accompanied by reduced abundance of adipocyte differentiation-related protein (ADRP) on LD surfaces. Using small hairpin RNA technology, we show that knock down of ADRP has a similar phenotypic effect on LD redistribution. Hence, ADRP is crucial to maintain a disperse intracellular distribution of LDs. From additional experimental evidence, LDs are associated with microtubules and aggregate principally around the microtubule-organizing centre in HCV-infected cells. Disrupting the microtubule network or microinjecting anti-dynein antibody prevented core-mediated LD redistribution. Moreover, microtubule disruption reduced virus titres, implicating transport networks in virus assembly and release. We propose that the presence of core on LDs favours their movement towards the nucleus, possibly to increase the probability of interaction between sites of HCV RNA replication and virion assembly.

Transport and egress of herpes simplex virus in neurons

The mechanisms of axonal transport of the alphaherpesviruses, HSV and pseudorabies virus (PrV), in neuronal axons are of fundamental interest, particularly in comparison with other viruses, and offer potential sites for antiviral intervention or development of gene therapy vectors. These herpesviruses are transported rapidly along microtubules (MTs) in the retrograde direction from the axon terminus to the dorsal root ganglion and then anterogradely in the opposite direction. Retrograde transport follows fusion and deenvelopment of the viral capsid at the axonal membrane followed by loss of most of the tegument proteins and then binding of the capsid via one or more viral proteins (VPs) to the retrograde molecular motor dynein. The HSV capsid protein pUL35 has been shown to bind to the dynein light chain Tctex1 but is likely to be accompanied by additional dynein binding of an inner tegument protein. The mechanism of anterograde transport is much more controversial with different processes being claimed for PrV and HSV: separate transport of HSV capsid/tegument and glycoproteins versus PrV transport as an enveloped virion. The controversy has not been resolved despite application, in several laboratories, of confocal microscopy (CFM), real-time fluorescence with viruses dual labelled on capsid and glycoprotein, electron microscopy in situ and immuno-electron microscopy. Different processes for each virus seem counterintuitive although they are the most divergent in the alphaherpesvirus subfamily. Current hypotheses suggest that unenveloped HSV capsids complete assembly in the axonal growth cones and varicosities, whereas with PrV unenveloped capsids are only found travelling in a retrograde direction.

Murray Valley encephalitis in an adult traveller complicated by long-term flaccid paralysis: case report and review of the literature

Murray Valley encephalitis (MVE) virus, a mosquito-borne flavivirus, is the most common cause of viral encephalitis in the tropical 'Top End' of northern Australia. Clinical encephalitis due to MVE virus has a mortality rate of approximately 30%, with a similar proportion of patients being left with significant neurological deficits. We report the case of a 25-year-old man from the UK who acquired MVE while travelling through northern Australia. He required prolonged admission to the Intensive Care Unit and several years later remains partly ventilator-dependent, with flaccid quadriparesis. To our knowledge, this is the first reported case of MVE virus-induced flaccid paralysis in an adult in northern Australia, although it is well described in children. Paralysis was thought to be due to anterior horn cell involvement in the spinal cord and extensive bilateral thalamic destruction, both of which are well recognised complications of infection with MVE virus. Cases of flaccid paralysis with similar pathology have been described following infection with the related flavivirus Japanese encephalitis virus as well as more recently with West Nile virus. Our case highlights the potential severity of flavivirus-induced encephalitis and the importance of avoiding mosquito bites while travelling through endemic areas.

The cycle of human herpes simplex virus infection: virus transport and immune control

After infection of skin or mucosa, herpes simplex virus enters the sensory nerve endings and is conveyed by retrograde axonal transport to the dorsal root ganglion, where the virus develops lifelong latency. Intermittent reactivation, which is spontaneous in humans, leads to anterograde transport of virus particles and proteins to the skin or mucosa, where the virus is shed and/or causes disease. Immune control of viral infection and replication occurs at the level of skin or mucosa during initial or recurrent infection and also within the dorsal root ganglion, where immune mechanisms control latency and reactivation. This article examines current views on the mechanisms of retrograde and anterograde transport of the virus in axons and the mechanisms of innate and adaptive immunity that control infection in the skin or mucosa and in the dorsal root ganglion--in particular, the role of interferons, myeloid and plasmacytoid dendritic cells, CD4(+) and CD8(+) T cells, and interferon- gamma and other cytokines, including their significance in the development of vaccines for genital herpes.

Tolerability of treatments for postherpetic neuralgia

Herpes zoster occurs in up to 20% of people infected with varicella-zoster virus, due to reactivation of the virus from latently infected sensory ganglia. Although pain is a typical feature of acute zoster, pain persisting for more than a month after resolution of the rash is less common and is termed postherpetic neuralgia (PHN). The pain associated with PHN is neuropathic in origin and is notoriously difficult to treat. The incidence of herpes zoster and its associated complications both increase with age, so PHN should be seen more commonly in an aging population. Vaccination with live, attenuated varicella vaccine is safe and efficacious, particularly in children. It decreases the incidence of acute varicella and subsequent herpes zoster. Aciclovir is well tolerated, with renal toxicity only at high intravenous doses. Treatment of acute varicella with aciclovir attenuates acute illness but does not prevent herpes zoster. Treatment of herpes zoster with aciclovir or its derivatives minimises symptoms and may reduce the rate of PHN. Foscarnet is an alternative for an aciclovir-resistant virus but its use is limited by renal and CNS toxicity. Corticosteroids reduce acute pain in herpes zoster but do not affect the incidence of PHN. Their use in some patients may be limited by adverse effects such as gastritis and impaired glucose tolerance. Treatment of established PHN is difficult and may require a holistic approach. Tricyclic antidepressants and gabapentin are the systemic agents with the most proven benefit, although opioids such as oxycodone and NMDA receptor antagonists such as ketamine may be useful in some people. Adverse effects from tricyclic antidepressants are common but usually mild, while gabapentin is generally well tolerated. Although effective, the relatively common adverse effects of opioids and ketamine limit their usefulness in treating PHN. Topical treatment with 5% lidocaine patch or capsaicin is of benefit in some patients and is generally well tolerated. Intrathecal methyl prednisolone may be considered for intractable pain but efficacy and safety have not been confirmed.

Determination of interactions between tegument proteins of herpes simplex virus type 1

The aim of this study was to elucidate protein-protein interactions between tegument proteins of herpes simplex virus type 1 (HSV-1). To do so, we have cloned and expressed in the LexA yeast (Saccharomyces cerevisiae) two-hybrid system, 13 of the 21 currently known tegument proteins of HSV-1. These included the tegument proteins essential for replication in cell lines, UL17, UL36, UL37, UL48, and UL49, and the nonessential tegument proteins US11, UL11, UL14, UL16, UL21, UL41, UL46, and UL47. A total of 104 combinations were screened in the yeast two-hybrid assay, with 9 interactions identified. These included: UL11-UL16, UL36-UL37, UL36-UL48, UL46-UL48, UL47-UL48, and UL48-UL49. The remaining interactions consisted of self-associations that were observed for US11, UL37, and UL49. The interactions UL36-UL37, UL36-UL48, UL37-UL37, UL46-UL48, and UL47-UL48 have not been previously reported for HSV-1. The interaction of UL46-UL48 was verified using an in vitro pull-down assay. The interactions of UL36-UL37 and UL37-UL37 were verified with a coimmunoprecipitation assay. Knowledge of HSV-1 tegument protein-protein interactions will provide insights into the pathways of tegument assembly, and the identified interactions are potential targets for new antiviral drugs.

The ribosome receptor, p180, interacts with kinesin heavy chain, KIF5B

The conventional microtubule-dependent motor protein kinesin consists of heavy and light chains both of which have been documented to bind a variety of potential linker or cargo proteins. In this study we employed a yeast two-hybrid assay to identify additional binding partners of the kinesin heavy chain isoform KIF5B. A human brain cDNA library was screened with a bait corresponding to amino acid residues 814-963 of human KIF5B. This screen identified the ribosome receptor, p180, as a KIF5B-binding protein. The sites of interaction are residues 1294-1413 of p180 and the C-terminal half of the cargo binding-domain of KIF5B (residues 867-907). The KIF5B-binding site in p180 is homologous to the previously determined KIF5B-binding site in kinectin. The interacting regions of p180 and KIF5B consist almost entirely of heptad repeats, suggesting the interaction is a coiled-coil. A role for the kinesin/p180 interaction may include mRNA localization and/or transport of endoplasmic reticulum-derived vesicles.

Epidemiology of community-acquired and nosocomial bloodstream infections in tropical Australia: a 12-month prospective study

OBJECTIVES

To define the relative incidence of organisms causing blood stream infections in a tropical setting with a very low prevalence of human immunodeficiency virus infection (<1%).

METHODS

A 12-month prospective study of blood stream infections in 2000 at Royal Darwin Hospital in the tropical north of Australia.

RESULTS

Significant isolates were grown from 257 sets of blood cultures. Staphylococcus aureus was the most common isolate overall (28%); 26% of these were methicillin-resistant (MRSA). Escherichia coli was the most common cause of community-acquired bacteraemia. Burkholderia pseudomallei caused 32% of community acquired, bacteraemic pneumonia; 6% of bacteraemias overall. Vancomycin-resistant enterococci were not isolated. Crude mortality rates (13% overall; 9% attributable mortality) were lower than in most comparable studies.

CONCLUSIONS

The major difference between these findings and surveys performed elsewhere is the presence of B. pseudomallei as a significant cause of bacteraemic community-acquired pneumonia. Our results demonstrate the effects of local environmental and patient characteristics on the range of organisms causing blood stream infections, and emphasize the important role of local microbiology laboratories in guiding empiric antibiotic therapy.

Minimum Phosphorus Requirement of One-Cycle and Two-Cycle (Molted) Hens

In experiment 1 (one cycle), hens were fed diets containing 0.10, 0.115, 0.125, 0.135, 0.15, or 0.45% available P (AP) from 40 to 56 wk of age, with the last diet being a positive control. Egg production, egg mass, and BW were reduced (P < 0.05) by all lower AP levels except 0.15% AP when compared with the 0.45% AP treatment. In the second experiment (two cycles with a molt), hens were initially fed diets containing 0.10, 0.12, 0.14, 0.16, 0.18, 0.20, or 0.45% AP from 21 to 63 wk of age. Diets containing 0.10, 0.12, and 0.14% AP were terminated at 35, 39, and 50 wk, respectively, due to low egg production and increased mortality. Hens fed 0.16% AP also had significantly lower production performance than hens fed 0.45% AP during the first cycle. Hens on the 0.16 to 0.45% AP treatments were induced molted at 64 wk of age by 10 d of feed removal. The hens were then returned to the same AP layer diet they had been fed from 21 to 63 wk. For the 68 to 108 wk postmolt second-cycle period, hens fed the 0.16 to 0.20% AP diets (166 to 209 mg/d) had significantly lower egg production, egg mass, and feed efficiency than hens fed 0.45% AP. The results of our study indicated that first-cycle hens required approximately 0.18% AP or 198 mg AP/hen per day, and molted hens in their second cycle had a requirement that was greater than 0.20% AP or 209 mg AP/hen per day.

Herpes simplex virus type 1 capsid protein VP26 interacts with dynein light chains RP3 and Tctex1 and plays a role in retrograde cellular transport

Cytoplasmic dynein is the major molecular motor involved in minus-end-directed cellular transport along microtubules. There is increasing evidence that the retrograde transport of herpes simplex virus type 1 along sensory axons is mediated by cytoplasmic dynein, but the viral and cellular proteins involved are not known. Here we report that the herpes simplex virus outer capsid protein VP26 interacts with dynein light chains RP3 and Tctex1 and is sufficient to mediate retrograde transport of viral capsids in a cellular model. A library of herpes simplex virus capsid and tegument structural genes was constructed and tested for interactions with dynein subunits in a yeast two-hybrid system. A strong interaction was detected between VP26 and the homologous 14-kDa dynein light chains RP3 and Tctex1. In vitro pull-down assays confirmed binding of VP26 to RP3, Tctex1, and intact cytoplasmic dynein complexes. Recombinant herpes simplex virus capsids were constructed either with or without VP26. In pull-down assays VP26+ capsids bound to RP3; VP26-capsids did not. To investigate intracellular transport, the recombinant viral capsids were microinjected into living cells and incubated at 37 degrees C. After 1 h VP26+ capsids were observed to co-localize with RP3, Tctex1, and microtubules. After 2 or 4 h VP26+ capsids had moved closer to the cell nucleus, whereas VP26-capsids remained in a random distribution. We propose that VP26 mediates binding of incoming herpes simplex virus capsids to cytoplasmic dynein during cellular infection, through interactions with dynein light chains.

Effect of soybean variety and processing on growth performance of young chicks and pigs

The objective of this study was to determine whether soybeans without the Kunitz trypsin inhibitor and lectins could be fed effectively to young chicks and pigs. Specifically, we compared the growth performance of chicks and pigs fed diets containing modified soybeans: Kunitz trypsin inhibitor-free (KF), lectin-free (LF), lectin and Kunitz trypsin inhibitor-free (LFKF), conventional soybeans (CSB), and commercially obtained, dehulled, solvent-extracted soybean meal (SBM). A 7-d chick experiment was conducted to evaluate the nutritional value of CSB, KF, LF, LFKF, and SBM. The experiment was conducted as a completely randomized design, with four replicates, five treatments, and six male chicks per pen (n = 120). The five treatments consisted of 23% CP dextrose-soybean-based diets containing KF, LF, LFKF, CSB, or SBM as the source of dietary protein. A 28-d pig experiment was conducted to evaluate the nutritional value of CSB, LF, LFKF, and SBM. Pens of four pigs were assigned randomly to a control, corn-SBM, or one of six corn-soybean diets containing raw or extruded soybean varieties as a 2 x 3 factorial arrangement of treatments in a randomized complete block design with five blocks per treatment (n = 140). Chicks fed diets containing any of the raw soybean varieties gained less weight (P < 0.05) than chicks fed SBM (22.81 g/d for SBM vs. 14.17 g/d for the raw soybeans combined). Among the raw soybean treatments, there was a greater effect on growth performance (P < 0.05) by removing both lectins and Kunitz trypsin inhibitor (ADG of 16.56 g for LFKF) than by removing each antinutritional factor separately (ADG of 14.38 and 14.11 g for KF and LF, respectively). Pig growth performance was different (P < 0.001) for SBM (ADG of 409 g) and all the varieties when extruded (ADG of 450 g for CSB, 417 g for LF, and 408 g for LFKF) compared with the raw soybean treatments (ADG of 101 g for CSB, 165 g for LF, and 266 g for LFKF). Among the raw soybean treatments, growth performance improved (P = 0.003) as the antinutritional factor, lectin, was removed from the soybean and improved further (P = 0.045) when both lectins and Kunitz trypsin inhibitor were removed. The growth-inhibiting effect of feeding modified soybeans to young animals was more detrimental for pigs than for chicks in our experiments. Soybeans without the Kunitz trypsin inhibitor and lectins cannot be fed successfully to young chicks and pigs without heating.

Impact of galactose, lactose, and Grobiotic-B70 on growth performance and energy utilization when fed to broiler chicks

Three chick assays were conducted to determine the effect of increasing dietary galactose (GAL), lactose (LAC), and Grobiotic-B70, a LAC fermentation product, on growth performance, toxicity, and energy utilization when fed to commercial broiler chicks. One-day-old male commercial broiler chicks were randomly assigned to treatments in each assay. In all assays, a 22% CP corn-soybean meal-dextrose basal diet containing a growth-promoting antibiotic (Bacitracin methylene disalicylate) was fed. In assay 1, GAL was added at 2, 4, 6, 10, or 15%. In assay 2, Grobiotic-B70 was added at 5%. In assay 3, GAL, LAC, and Grobiotic-B70 were each added at 2, 4, and 6%. All additions were made in place of dextrose, and diets were fed from 0 to 20 or 21 d of age. In assay 1, the 15% GAL treatment resulted in high mortality (27%) by d 3 and was terminated. The 10% GAL treatment also resulted in increased mortality, most of which occurred during the 7-to-14-d period. Inclusion of 2 and 4% GAL resulted in an improvement (P < 0.05) in growth compared to the basal diet. Inclusion of 2, 4, 6, and 10% GAL resulted in a significant linear decrease in MEn (r2 = 0.85). In chick assay 2, 5% Grobiotic-B70 increased growth during the first 2 wk. In chick assay 3, 6% Grobiotic increased weight gain (P < 0.05) from 0 to 14 d, and addition of 2 or 4% GAL, 2 or 4% LAC, and 4 or 6% Grobiotic-B70 increased weight gain (P < 0.08) from 0 to 21 d. Our results indicate that levels of 10 to 15% GAL are toxic. In contrast, low levels of GAL and Grobiotic-B70, and possibly LAC, may increase growth of commercial broiler chicks.

Efficacy of high available phosphorus corn in laying hen diets

Our objective was to determine if high available phosphorus corn would provide sufficient available phosphorus (AP) to laying hens fed corn-soybean meal diets from 57 to 69 wk of age. Six replications of 12 Dekalb Sigma Leghorn hens were fed a normal yellow dent (YD) corn-soybean meal diet or high available phosphorus (HAP) corn-soybean meal diet without and with 0.04% supplemental inorganic P. The unsupplemented YD diet was calculated to contain 17% CP, 3.8% Ca, and 0.10% AP, and the unsupplemented HAP diet contained 17% CP, 3.8% Ca, and 0.16% AP. In addition, a positive control, YD diet (17% CP, 3.8% Ca, 0.45% AP) was also fed. The HAP corn was directly substituted for YD on a weight basis, and the amount of soybean meal was kept constant in all diets. Egg production, hen body weight, egg weight, egg mass, feed consumption, and feed efficiency were measured. The YD and the YD + 0.04% P treatments were terminated at 61 and 65 wk of age, respectively, due to severe depressions in egg production. Egg production and egg mass for hens fed HAP diets were not different (P > 0.05) from those of hens fed the 0.45% AP diet; however, hens fed the unsupplemented HAP diet did have lower hen body weights and feed intake (P < 0.05) compared to hens fed the positive control diet. Our results indicate that HAP corn contains more available P than normal YD corn and that hens can be fed HAP corn-soybean meal diets containing little or no P supplementation with only minimal effects on production performance.

Evaluation of nonfeed removal methods for molting programs

An experiment was conducted using 336 White Leghorn hens (60 wk of age) randomly assigned to one of four treatments that consisted of feed removal for 4 or 10 d or no feed removal with ad libitum access to 95% corn or 95% wheat middlings molt diets that contained supplemental minerals and vitamins. At the end of the 4- or 10-d feed removal period, hens on these treatments were provided with the corn molt diet for 24 or 18 d, respectively. Hens on the corn or wheat middlings treatments were fed the diets for 28 d. At d 28, hens on all treatments were fed a corn-soybean meal (16% CP) layer diet for 40 wk (64 to 104 wk of age). Both feed removal and the wheat middlings treatments resulted in total cessation of egg production within 8 d. Egg production of hens fed the corn molt diet had decreased to 3% by d 28. Body weight loss for hens fed the corn or wheat middlings diet was approximately 15 and 8% at d 28, respectively. Hens fed the wheat middlings diet returned to production slightly faster than hens on the other treatments. Postmolt egg production and egg mass (wk 5 to 44) were generally higher for the wheat middlings and 10-d feed removal treatments than for the corn or 4-d feed removal treatments. There were no consistent differences in mortality, egg weight, egg specific gravity, feed efficiency, and layer feed consumption among treatments. This research indicates that diets with high corn or wheat middlings, particularly wheat middlings, are effective nonfeed removal methods for molting hens.

Phytase effects on amino acid digestibility in molted laying hens

Two hundred sixteen previously molted Dekalb Delta Leghorn laying hens (78 wk of age) were utilized to determine the effect of phytase on the ileal digestibility of amino acids. The hens were randomly arranged in a 3 x 2 factorial to evaluate three diet types that were corn-soybean meal (C-SBM), C-SBM-meat and bone meal (C-SBM-MBM), and C-SBM-wheat middlings (C-SBM-WM) and two levels of phytase (0 or 300 U/kg of diet). Each treatment was administered to four replicates of nine hens per replicate. Hens were fed the experimental diets for 21 d, and daily egg production and feed intake were recorded. After 21 d, the hens were euthanized, and ileal contents were collected for amino acid and digestible energy determination. Egg production of the hens did not differ among the treatments (P > 0.05). A significant interaction between diet type and phytase level for Ala, Gly, Leu, and Met was observed. The interaction resulted because phytase numerically increased amino acid digestibilities for the C-SBM-MBM and C-SBM-WM diets, but phytase addition numerically decreased the amino acid digestibilities for the C-SBM diet. Diet type had a significant effect on digesibilites of most amino acids. The latter effect was due primarily to lower amino acid digestibilities for the C-SBM-MBM diet than the C-SBM-WM diet. Phytase had no significant affect on digestibility of any amino acid. Ieal digestible energy was significantly affected by diet type but not by phytase. In conclusion, diet type had a significant effect on apparent ileal amino acid digestibility and digestible energy, but phytase had no consistent effect.

The heavy chain of conventional kinesin interacts with the SNARE proteins SNAP25 and SNAP23

Recent studies on the conventional motor protein kinesin have identified a putative cargo-binding domain (residues 827-906) within the heavy chain. To identify possible cargo proteins which bind to this kinesin domain, we employed a yeast two-hybrid assay. A human brain cDNA library was screened, using as bait residues 814-963 of human ubiquitous kinesin heavy chain. This screen initially identified synaptosome-associated protein of 25 kDa (SNAP25) as a kinesin-binding protein. Subsequently, synaptosome-associated protein of 23 kDa (SNAP23), the nonneuronal homologue of SNAP25, was also confirmed to interact with kinesin. The sites of interaction, determined from in vivo and in vitro assays, are the N-terminus of SNAP25 (residues 1-84) and the cargo-binding domain of kinesin heavy chain (residues 814-907). Both regions are composed almost entirely of heptad repeats, suggesting the interaction between heavy chain and SNAP25 is that of a coiled-coil. The observation that SNAP23 also binds to residues 814-907 of heavy chain would indicate that the minimal kinesin-binding domain of SNAP23 and SNAP25 is most likely residues 45-84 (SNAP25 numbering), a heptad-repeat region in both proteins. The major binding site for kinesin light chain in kinesin heavy chain was mapped to residues 789-813 at the C-terminal end of the heavy chain stalk domain. Weak binding of light chain was also detected at the N-terminus of the heavy chain tail domain (residues 814-854). In support of separate binding sites on heavy chain for light chain and SNAPs, a complex of heavy and light chains was observed to interact with SNAP25 and SNAP23.

Efficacy of phytase for increasing protein efficiency ratio values of feed ingredients

Data previously reported in several studies have suggested that phytase improves amino acid digestibility in chicks. It was the objective of the current study to determine if phytase would increase the protein efficiency ratio (PER) values (g weight gain per g protein intake) for several feed ingredients fed to chicks. Six experiments were conducted and ingredients evaluated were casein, soybean meal, canola meal, cottonseed meal, peanut meal, wheat middlings, wheat bran, rice bran, defatted rice bran, meat and bone meal, and corn gluten meal. Casein was evaluated to serve as a phytate-free control ingredient. Each feedstuff was analyzed for CP and included in cornstarch:dextrose diets as the only source of protein to provide 10% dietary protein in Experiments 1 to 5 or 18% dietary protein (soybean meal) in Experiment 6. Dietary Ca and nonphytate P levels were varied among experiments and ranged from 0.95 to 1.5% Ca and 0.35 to 0.675% nonphytate P. The test ingredient diets were fed with 0 or 1,200 units of phytase/kg to New Hampshire x Columbian chicks from 8 to 17 or 20 d of age. The PER values varied greatly among ingredients, ranging from 1.4 for corn gluten meal to 4.2 for canola meal. Phytase addition had no significant effect (P > 0.10) on PER values for any of the ingredients evaluated, except for an increase for casein in one experiment. The results indicated that 1,200 U of phytase/kg did not significantly increase protein utilization of several feed ingredients as assessed by a PER chick growth assay.

Multi-drug resistant Pseudomonas aeruginosa outbreak in a burns unit--an infection control study

A newly introduced, multi-drug resistant (MDR) strain of Pseudomonas aeruginosa was isolated from four patients admitted to the Concord Hospital Burns Unit (BU) between December 1997 and March 1998. It was the cause of recurrent episodes of bacteraemia in two. This strain was resistant in vitro to gentamicin, piperacillin and ciprofloxacin. The isolates were confirmed as a clonal strain by pulse field gel electrophoresis (PFGE). Multiple environmental swabs were taken to search for an environmental reservoir, but no source was identified. Random cultures of staff members' hands failed to demonstrate ongoing carriage. In the absence of a demonstrable point source for the outbreak, direct cross-transmission patient to patient, via transient staff hand contamination, was the most likely route of infection. Following study commencement no new cases of infection with the MDR strain were detected. It would appear that the infection cycle has been interrupted, and the outbreak terminated following the discharge of the last infected patient from the BU. Contamination of a neutral detergent in the BU with Klebsiella oxytoca was detected incidentally during environmental surveillance. A potential hospital-wide outbreak was averted.

Early postmolt performance of laying hens fed a low-protein corn molt diet supplemented with spent hen meal

We used a total of 504 commercial Single Comb White Leghorn hens (69 and 65 wk of age) in each of two experiments, and hens were induced to molt by feed withdrawal only. Feed withdrawal lasted for 12 and 11 d, and hens lost 26 and 25%, body weight in Experiments 1 and 2, respectively. All hens were then weighed, and seven replicate groups of 12 hens each were assigned to molt diet treatments. In Experiment 1, diets consisted of a corn basal diet (7.9% CP) or corn basal diet supplemented with 7.5 or 10% spent hen meal (SHM) each from two different sources. In Experiment 2, the corn basal diet or this diet supplemented with 5 or 10% SHM alone or 5% SHM plus Met, Lys, and Trp was evaluated. A molt diet of 16% CP corn-soybean meal was used as a positive control in both experiments. Molt diets were fed for 15 d in both experiments, at which time all hens were fed a 16% CP layer diet. Performance was measured for 8 wk following the beginning of feeding the layer diet. Feeding the low-protein corn molt diet supplemented with 5 to 10% SHM improved early postmolt egg production performance and body weight gain compared with hens fed the corn basal diet alone. The 7.5 and 10% SHM diets yielded early postmolt performance that was not significantly different (P > 0.05) from that of hens fed the high-protein (16% CP) diet. Supplementing the 5% SHM diet with amino acids generally did not significantly improve performance. The present study thus indicates that improved early postmolt performance may be achieved by supplementation of a low-protein corn molt diet with 5 to 10% SHM.

Protein dispersibility index as an indicator of adequately processed soybean meal

Three chick assays (8 to 17 or 21 d) were conducted to evaluate protein dispersibility index (PDI) as an indicator of minimum adequate heat processing of soybean meal compared with the urease index and protein solubility in 0.2% KOH. Solvent-extracted soyflakes (SF) were subjected to various autoclaving times at 121 C and 105 kPa and were included in 23% CP dextrose-SF diets or 20% CP corn-SF-corn gluten meal diets. Autoclaving times in Chick Assays 1, 2, and 3 were 0 to 36 min, 0 to 30 min, and 0 to 12 min, respectively. Body weight gains and gain-to-feed ratios increased (P < 0.05) with increased SF heating time (0 to 18 min in Chick Assay 1, 0 to 10 min in Chick Assay 2, and 0 to 9 min in Chick Assay 3), with no additional improvement for longer autoclaving times. Urease index values (pH increase) were high initially and at the shorter autoclaving times (1.65 to 2.4), and then decreased suddenly to 0.3 or below as autoclaving time increased in two of the three chick assays. The KOH protein solubility values generally decreased as autoclaving time increased, but the responses were often inconsistent. Protein dispersibility index displayed the most consistent responses to heating time: it decreased from above 70% to generally below 30% as autoclaving time increased from 0 to 30 or 36 min (mean r2 from linear regression of PDI on autoclaving time was 0.92 for the three chick assays). The latter responses were particularly evident for the heating times, which yielded the greatest changes in chick growth performance. These results suggest that PDI is a more consistent and sensitive indicator of minimum adequate heat processing of soybean meal than urease index or protein solubility in KOH.

Nutritional evaluation of low phytate and high protein corns

Three chick experiments and two cecectomized rooster experiments were conducted to determine P bioavailability and amino acid (AA) digestibility in two low phytate corns (LP), a high protein corn (HP), and a corn containing both low phytate and high protein content (HP/LP) compared with conventional corn (CONV). From 8 to 20 or 21 d of age, 1-wk-old New Hampshire x Columbian chicks were fed a cornstarch-dextrose-soybean meal (SBM) basal diet containing 0.10% available P or the basal diet supplemented with two concentrations of P (0.05 or 0.06% and 0.10 or 0.12%) from KH2PO4 or two concentrations of the corns (20 or 21% and 40 or 42%). Bioavailability of P based on tibia bone ash was much higher for LP than for CONV; values ranged from 21 to 40% for CONV and from 59 to 95% for LP. Digestibility of AA in cecectomized roosters indicated no significant differences (P > 0.05) between CONV and HP in the first rooster experiment. Digestibilities of eight AA, including lysine, methionine, and arginine, in LP and HP/LP were higher (P < 0.05) than those in CONV in the second rooster experiment. The results of this study indicated that the P in LP was two to three times more bioavailable than the P in CONV and that the digestibilities of AA in HP/LP were equal to or higher than those in CONV.

Effect of presolvent extraction processing method on the nutritional value of soybean meal for chicks

This study evaluated the effect of extruding or expander processing prior to solvent extraction on the nutritional value of soybean meal (SBM). Three samples of SBM containing 100% nonexpander SBM, 100% expander SBM, or a mixture of nonexpander and expander SBM were obtained from a commercial plant. An experiment was conducted using Peterson x Hubbard commercial male broiler chicks fed 20% CP corn-SBM-corn gluten meal diets from 8 to 21 d of age. The experiment had a 3 x 2 x 2 factorial design, with three SBM types, two levels of Met + Cys (0.77 and 0.90%), and two levels of Lys (0.95 and 1.20%). Processing method had no effect on the amino acid concentration or protein solubility of the SBM. Dietary treatment had no significant effect on chick weight gain or feed intake. Feed efficiency was significantly improved (P < 0.05) by Met and Lys supplementation, but SBM processing method had no significant effect. The results of this study indicate that presolvent processing method (expander or nonexpander) had no significant effect on the nutritional value of SBM for broiler chicks.

Citric acid does not improve phosphorus utilization in laying hens fed a corn-soybean meal diet

Data previously obtained from our laboratory have indicated that citric acid was very effective at improving phytate-P utilization in chicks fed a P-deficient corn-soybean meal (SBM) diet. The objective of the current study was to determine if citric acid would have similar effects in a commercial strain of Single Comb White Leghorn laying hens (n = 432) fed a corn-SBM diet containing 0.10% available P (AP). Dietary treatments were a corn-SBM basal diet (0.10% AP, 3.8% Ca, and 17% CP) supplemented with 0, 1, 2, 3, or 4% citric acid and a positive control diet containing 0.45% AP. Each of the six dietary treatments were fed to six replicate groups of 12 hens from 22 to 40 wk of age. No significant differences in performance were observed among treatments during the first 4 wk of the experiment. Hen-day egg production, feed consumption, feed efficiency, and egg yield were subsequently depressed in hens fed 0, 1, 2, 3, or 4% citric acid compared with hens fed 0.45% AP. The results of this study indicate that citric acid does not improve the utilization of dietary P in laying hens fed a corn-SBM diet containing 3.8% Ca.

The effects of various dietary levels of phytase and available phosphorus on performance of laying hens

Data previously obtained from our laboratory indicated that addition of 300 U of phytase/kg diet supported optimal long-term performance of laying hens (20 to 70 wk) fed a corn-soybean meal (SBM) diet containing 0.10% available phosphorus (AP). Our primary objective was to determine if a phytase level lower than 300 units/kg is adequate for a commercial strain of Single Comb White Leghorn laying hens (n = 504) fed a corn-SBM diet containing no supplemental P (0.10% AP). Dietary treatments consisted of the corn-SBM basal diet (0.10% AP, 3.8% Ca, and 17% CP) supplemented with 0, 100, 200, 250, or 300 U of phytase/kg, 0.05% inorganic P (0.15% AP), and a positive control diet containing 0.45% AP. Each of the seven dietary treatments was fed to six replicate groups of 12 hens from 20 to 60 wk of age. No significant differences in performance were observed among treatments during the first 8 wk of the experiment. By 28 wk of age, the 0.10% AP diet, with no supplemental phytase or P, resulted in significantly lower (P < 0.05) egg production and body weight compared with all other dietary treatments. Feed consumption, feed efficiency, and egg yield were subsequently depressed by 32 wk of age in hens fed the 0.10% AP diet. No other significant differences among treatments were observed for performance averaged over the entire 40-wk experimental period. The mean daily AP intake of hens fed the 0.15% AP, 0.45% AP, and 0.10% AP + phytase diets was 155, 474, and 103 mg, respectively. The results of this study indicate that phytase improves the utilization of P in corn-SBM diets for laying hens and that corn-SBM diets containing 0.10% AP + 100 units of phytase/kg diet or 0.15% AP supported egg production performance that was not significantly different (P > 0.05) from that of hens fed a corn-SBM diet containing 0.45% AP.

Protein and energy evaluation of soybean meals processed from genetically modified high-protein soybeans

A conventional and two genetically modified soybean samples were processed to dehulled soybean meal (SBM) at a pilot plant and were compared with SBM from a commercial processing plant. Crude protein levels (%) of the experimental SBM samples were M700, 52.5; M702, 53.4; and M703, 62.7. The commercial SBM sample (UI) contained 47.5% protein. Amino acid, gross energy, lipid, and fiber analyses were carried out, and true metabolizable energy and true amino acid digestibility were determined with adult cecectomized cockerels. Digestible Lys, Met, Cys, Thr, and Val, and also TMEn, were higher (P < 0.05) and NDF, fat, and phospholipids were lower in M703 than in the other SBM samples. The results of this study indicate that M703 has considerable advantages over conventional SBM as a feed ingredient for broiler chickens.

The effects of dietary available phosphorus levels and phytase on performance of young and older laying hens

In the first of two experiments (20 to 70 wk of age), eight treatments consisted of corn-soybean meal diets (0.34% total P, 3.8% Ca, 17% CP, 2,758 kcal ME/kg) containing 0.10, 0.15, 0.20, 0.25, or 0.45% available P (AP), with the three lowest AP diets supplemented with 300 units of phytase/kg of diet. A second experiment evaluated the effect of feeding the 0.10% AP diet with and without phytase on performance and time required for onset of P deficiency in older hens (70 to 76 wk of age). In Experiment 1, the 0.10% AP diet with no supplemental phytase depressed performance by 28 wk of age. No other significant differences in performance were observed among treatments for the entire 20- to 70-wk period except that the 0.15% AP diet with no phytase resulted in body weights and tibia ash that were lower (P < 0.05) than those of hens fed the 0.45% AP diet during the last 30 wk. The mean daily AP intake of hens fed the 0.10% AP, 0.15% AP, 0.45% AP, or 0.10% AP + phytase diets was 94,159, 499, or 108 mg, respectively. Excreta P concentration was decreased by approximately 50% in birds consuming 0.10% AP + 300 U/kg phytase compared with those consuming 0.45% AP. In the second experiment, P deficiency signs occurred within 3 wk of consuming the unsupplemented corn-soybean meal diet (0.10% AP) compared with 8 wk in Experiment 1. The results of this study indicate that phytase improves P utilization in corn-soybean meal diets for laying hens and that a corn-soybean meal diet containing 0.15% AP (159 mg AP/d) or containing 0.10% AP + 300 units of phytase/kg (108 mg AP/d) supported optimal egg production from 20 to 70 wk of age. Additionally, results suggested that older hens may exhibit P deficiency symptoms sooner than younger hens.

Early postmolt performance of laying hens fed a low-protein corn molt diet supplemented with corn gluten meal, feather meal, methionine, and lysine

Commercial White Leghorn hens (65, 63, or 70 wk of age in Experiments 1, 2, and 3, respectively) were induced molted by feed withdrawal until approximately 28% body weight was lost. All hens were then weighed, and seven replicate groups of 12 hens each were fed molt diets. In Experiment 1, three diets consisted of a corn basal diet (7.9% CP) or this diet supplemented with corn gluten meal (CGM) and Lys or feather meal (FM), Met, and Lys. In Experiments 2 and 3, varying levels of FM and FM with Met and Lys were evaluated. A 16% CP corn-soybean meal diet was used as a positive control in all experiments. The molt diets were fed for 17, 15, and 17 d in Experiments 1, 2, and 3, respectively, and production performance was measured for 8 wk from the beginning of feeding the layer diet. In all experiments, hens fed the 16% CP corn-soybean meal molt diet returned to egg production and regained body weight at a faster rate than did hens fed any of the other diets. In Experiment 1, early egg production of hens fed the corn basal diet supplemented with CGM and Lys or supplementation with FM, Met, and Lys was greater (P < 0.05) than that of hens fed the basal diet alone. In Experiment 2, very early egg production (Week 1) and body weight gain were lower (P < 0.05) for hens fed the corn basal diet than for hens fed the basal supplemented with FM, Met, and Lys. The addition of 5.75 or 8.5% FM or 5.75% FM plus Met and Lys generally increased (P < 0.05) early egg production and postmolt body weight gain compared to the corn basal diet in Experiment 3. The present study thus indicated that improved early postmolt performance may be achieved by supplementation of a low-protein corn molt diet with various combinations of CGM, FM, Met, and Lys.

Dietary formulation with rendered spent hen meals on a total amino acid versus a digestible amino acid basis

Previous results indicated that performance of chicks fed a high level (15%) of rendered spent hen meal (SHM) was lower than performance of chicks fed a corn-soybean meal (SBM) diet. The latter difference was hypothesized to be due to variation in digestible amino acid (AA) levels among the diets. This study evaluated diets containing SHM formulated on an equivalent total AA basis vs an equivalent digestible AA basis compared to a corn-SBM diet. Three SHM (A, B, and C), produced in commercial rendering plants, were evaluated. Mean true digestibility coefficients (percentages) for 17 AA in SHM A, B, and C were 73.1, 63.4, and 75.5, respectively. In two chick trials, 1-wk-old New Hampshire x Columbian male chicks were fed from 8 to 20 d of age a corn-SBM diet or diets containing 15% SHM formulated to be equal in total or digestible AA to the corn-SBM diet. All diets contained 21.5% CP and 3,200 kcal TME(n)/kg. Chicks fed 15% SHM (A, B, or C) diets formulated on a total AA basis had significantly lower (P < 0.05) weight gain and feed efficiency than chicks consuming the corn-SBM diet. Formulating diets containing SHM B or SHM C on a digestible AA basis yielded growth performance equivalent to chicks fed the corn-SBM diet. Growth performance of chicks fed the SHM A diet formulated on a digestible AA basis was greater (P < 0.05) than that obtained from the SHM A diet formulated on a total AA basis but was still lower than performance of chicks consuming the corn-SBM diet. Additional AA and energy supplementation of the SHM A diet formulated on a digestible AA basis only partially alleviated the latter performance difference. The results of this study indicated that formulation of diets containing SHM on a digestible AA basis is superior to formulation on a total AA basis and that 15% inclusion of two of the three SHM in chick diets had no detrimental effects on performance if the diets were formulated to contain adequate levels of digestible AA.

Bioavailability of lysine from a liquid lysine source in chicks

Two experiments were conducted to assess the bioavailability of lysine from a liquid lysine product (LLP; 60% lysine) relative to crystalline L-lysine.HCl. In the first experiment, four groups of five chicks were fed a lysine-deficient basal diet containing corn, soybean meal, and feather meal or the basal diet supplemented with 0.1 or 0.2% lysine from L-lysine.HCl or LLP from Day 8 to 22 posthatching. Weight gain and feed efficiency responded linearly (P < 0.01) to increasing levels of lysine from either lysine source, and multiple linear regression analysis of weight gain regressed on supplemental lysine intake indicated no difference (P > 0.05) in the response to lysine from L-lysine.HCl or LLP. Experiment 2 was conducted using a lysine-deficient basal diet containing corn, peanut meal, and feather meal, and all diets were fed to five groups of five chicks from Day 8 to 21 posthatching. Treatment additions again consisted of 0.1 or 0.2% lysine from L-lysine.HCl or LLP. Weight gain and feed efficiency responded linearly (P < 0.01) to increasing levels of lysine from L-lysine-HCl and LLP, and multiple linear regression analysis of weight gain regressed on supplemental lysine intake indicated no difference (P > 0.05) in the response to lysine from L-lysine.HCl or LLP. These data indicate that lysine from LLP is fully bioavailable relative to lysine from crystalline L-lysine.HCl, and could therefore be used as a source of lysine in practical poultry diets.

Nutritional evaluation of lectin-free soybeans for poultry

This study evaluated the nutritional value of raw lectin-free soybeans in comparison with raw Kunitz trypsin inhibitor-free soybeans, raw conventional soybeans, and commercial heat processed soybean meal (SBM). Analyzed lectin values (milligrams per kilogram) were 7.2, 7.1, and < 0.00015 for the Kunitz-free, conventional, and lectin-free soybeans, respectively. Three experiments were conducted using New Hampshire x Columbian male chicks fed 23% CP dextrose-soybean diets from 8 to 17 d of age. Growth performance of chicks fed lectin-free soybeans was greater (P < 0.05) than that of chicks fed raw conventional soybeans in all three experiments. However, performance of chicks fed lectin-free soybeans was lower than that of chicks fed Kunitz-free soybeans or SBM. The SBM yielded weight gains and feed efficiencies that were much higher than those observed from any of the raw soybeans. True amino acid digestibility and TMEn of the lectin-free and conventional soybeans were determined using the precision-fed cecectomized rooster assay. Seven roosters were crop-intubated with 30 g of soybeans and excreta were collected for 48 h. Digestibility coefficients of most amino acids for lectin-free soybeans were 5 to 8 percentage units higher than those for conventional soybeans, but the differences were not significant (P > 0.05). Likewise, the TMEn for lectin-free soybeans was 11% higher than that for raw conventional soybeans (3.577 vs 3.227 kcal/g DM) but the difference was not significant (P > 0.05). The results of this study indicate that the nutritional value of raw lectin-free soybeans is greater than raw conventional soybeans but is less than raw Kunitz-free soybeans and SBM, suggesting that trypsin inhibitor is a greater antinutritional factor than lectins.

Impact of feeding regimen on behavioral and physiological indicators for feeding motivation and satiety, immune function, and performance of gestating sows

The effect of daily or interval (every 3 d) feeding on body weight change, blood glucose and cholecystokinin (CCK) concentrations, immune function, and behavioral activity were determined during the gestation period of sows. Sows were fed a corn-soybean meal diet either 2 kg daily or 6 kg once every 3rd d (interval). Body weight changes for the 42-d trial period were not different (P > .05) between regimens. Blood glucose concentrations were similar before feeding (P > .05). Two hours after feeding, glucose concentrations increased in interval-fed sows but not in daily-fed sows (P < .05). Premeal plasma CCK concentrations were greater for daily-fed sows than for interval-fed sows (P < .05). The CCK concentrations in sows of both regimens increased after feeding above premeal levels (P < .05), and interval-fed sows exhibited higher concentrations than daily-fed sows (P < .05). Immune function as evaluated through mitogen-induced proliferation of T cells was greater in daily-fed sows than in interval-fed sows (P < .05). Daily-fed sows were more active overall and on any given day than interval-fed sows (P < .05) and thus seemed to expend more energy. Further, daily-fed sows exhibited higher levels of mouth-based activities (i.e., sham chewing, licking, appetitive and consummatory feeding behavior, and excess drinking) than sows restricted to consumption of one large meal every 3rd d. These indicators suggest that feeding motivation significantly affected overall performance of sows. This study emphasizes the need for evaluating the impact of feeding regimens and meal size on feeding motivation and, ultimately, on the well-being of the gestating sows.

Evaluation of protein and energy quality of rendered spent hen meals

This study evaluated three spent hen meals (SHM) that were produced in commercial rendering plants. The levels (percentage) of selected nutrients (mean and range) in the meals were: CP, 64 (56 to 71); ash, 16 (12 to 18); lysine, 4.0 (3.6 to 4.3); methionine, 1.3 (1.2 to 1.4); cystine, 1.1 (0.8 to 1.5). Protein efficiency ratios (PER; weight gain per unit of protein intake) were determined in chicks fed 10% CP diets containing a SHM as the only source of dietary protein. The PER values for the SHM averaged 1.6 but varied from 1.1 to 2.2. An experiment was conducted using New Hampshire x Columbian chicks during the 7 to 20 d age period to determine the effect of substitution with either 7.5 or 15% of a SHM to a 21.5% CP corn-soybean meal diet. When substituted at 7.5%, growth performance was not affected by two of the SHM but was depressed by the other one. Growth performance was decreased by all SHM when substituted at 15% of the diet. True amino acid digestibility and TMEn of the SHM were determined using the precision-fed cecectomized rooster assay in which four roosters were crop-intubated with 30 g of a SHM and excreta were collected for 48 h. True amino acid digestibility varied among SHM (P < or = 0.05) and digestibility of cystine was substantially lower than digestibility of the other amino acids. Mean TMEn (kilocalories per gram of DM) of the SHM was 3.003 but varied by 44% among samples. The results of this study indicated that SHM has substantial nutritional value for poultry but the nutritional quality may vary greatly among samples.

CTL recognition of west Nile virus-infected fibroblasts is cell cycle dependent and is associated with virus-induced increases in class I MHC antigen expression

Confluent and non-confluent mouse embryo fibroblast (CMEF and NCMEF) monolayers were infected with West Nile virus (WNV) for 24 hr, and class I major histocompatibility complex antigen (MHC-I) concentrations measured by flow cytometry (FCM). Concentrations on CMEF increased significantly more than on NCMEF. This was not owing to differences in interferon-beta (IFN-beta)-mediated MHC induction, as the IFN-beta quantity secreted by each infected fibroblast was similar in each culture, and IFN-beta-mediated MHC-I induction on NCMEF was greater than on CMEF. Furthermore, despite neutralization of WNV-induced supernatant IFN-beta, CMEF increased MHC-I expression significantly more than NCMEF. Functionally, WNV-infected CMEF were lysed 10-fold better by WNV-specific and allospecific cytotoxic T cells, than infected NCMEF. FCM demonstrated 76% CMEF and 68% NCMEF distributed in G0/G1. This represented G0 in CMEF, and G1 in NCMEF, confirmed by ribonucleotide reductase M1 subunit labelling, where only 20% CMEF was labelled, compared to 84% NCMEF. The possible implications for antiviral immune responses are discussed.

The effects of West Nile virus on major histocompatibility complex class I and II molecule expression by Lewis rat Schwann cells in vitro

The expression of major histocompatibility complex (MHC) class I and II molecules by Lewis rat Schwann cells after infection with West Nile virus (WNV) in vitro was examined by fluorescence microscopy and flow cytometry. WNV enhanced the expression of MHC class I molecules and induced the expression of MHC class II molecules by Schwann cells. Irradiated medium from WNV-infected Schwann cell cultures upregulated class I molecule expression on dissociated Schwann cell cultures but did not induce the expression of class II molecules. This finding has implications for virally triggered autoimmune diseases of nervous tissue.