Organ growth and fermentation profiles of broilers differing in body growth rate

This study sought to determine the relationship among broiler performance, organ development, and indicators of microbiota colonization. A total of 1,200 two-day-old male Ross 308 broiler chicks, divided among 3 cohorts of equal size, were housed in battery cages, and allotted based on body weight. On study d 11, birds were weighed, and birds with BW gain within the 10th and 90th percentiles were assigned to the Slow and Fast groups, respectively. Birds (n = 30 for each group) selected on d 11 were provided water and a corn-soybean meal-based diet ad libitum while maintained individually through study d 25 (i.e., a 14-d growth period). Parameters regarding growth performance, organ and intestine weights and lengths, and intestinal volatile fatty acid concentrations were measured. All data were analyzed by one-way ANOVA using the Mixed procedure of SAS. Fast birds exhibited greater (P < 0.001) BW gain and feed intake than slow birds, but feed conversion ratio (FCR) did not differ (P = 0.19). Additionally, Slow birds had higher (P < 0.05) relative weights (% of BW) for nearly all organs on d 11 and 25, most notably the gizzard, proventriculus, pancreas, and liver. Conversely, intestinal sections were longer (P < 0.05) in the Fast birds. Measurement of gut histomorphology did not show any notable differences between growth rate groups in terms of villi height, crypt depth, or their ratio for either time-point (P > 0.05). In terms of volatile fatty acid concentrations of luminal contents, acetate concentrations were 10.2% higher (P < 0.001) in the ileum of the Slow birds compared with Fast birds on d 25. Overall, the findings suggest that total BW gain is influenced by the development of metabolically active organs, as supported by lower weight gain in Slow birds with relatively larger organ weights and shorter intestinal lengths than their Fast counterparts. The general lack of differences in fermentation end-product concentrations in luminal contents does not rule out influence of the microbiota on growth rate of broilers, which warrants further investigation.

Dose-Dependent Effects of Supplementing a Two-Strain Bacillus subtilis Probiotic on Growth Performance, Blood Parameters, Fecal Metabolites, and Microbiome in Nursery Pigs

This experiment was conducted to evaluate the effects of dietary supplementation level of a two-strain Bacillus subtilis probiotic on growth performance, blood parameters, fecal metabolites, and microbiome in nursery pigs. A total of 54 weaned piglets were allotted to three treatments in three replicate pens with six pigs/pen for a 28 d feeding trial. The treatments were as follows: control: no probiotic supplementation; Pro1x: B. subtilis supplementation at 1.875 × 105 CFU/g diet; and Pro10x: B. subtilis supplementation at 1.875 × 106 CFU/g diet. Body weight at d 14 postweaning (p = 0.06) and average daily gain for d 0 to 14 postweaning (p < 0.05) were greater in the Pro1x treatment than in the other treatments. Blood glucose levels were greater in both probiotic treatments than in the control treatment at d 14 postweaning (p < 0.05). In the fecal short-chain fatty acid (SCFA) concentrations, the butyrate concentrations were greater in the Pro1x treatment than in the other treatments (p < 0.05), and the acetate, propionate, and total SCFA concentrations were greater in the Pro1x treatment than in the Pro10x treatment (p < 0.05). The beta diversity of fecal microbiome composition at d 14 postweaning based on Unweighted Unifrac analysis was dissimilar between the Pro1x and Pro10x treatments (p < 0.05). In conclusion, dietary B. subtilis supplementation of two strains selected to reduce effects of pathogenic Escherichia coli to nursery diets at 1.875 × 105 CFU/g diet improved the growth rate in the early postweaning period, increased fecal SCFA concentrations and altered the fecal microbial community composition. A higher dose of B. subtilis did not improve the performance parameters over those of the control piglets.

Collagen adhesin protein and necrotic enteritis B-like toxin as biomarkers for early diagnosis of necrotic enteritis in commercial broiler chickens

Mouse monoclonal antibodies (mAbs) reactive with Clostridium perfringens collagen adhesin protein (CNA) and necrotic enteritis B-like toxin (NetB) were developed. The best capture/detection mAb pairs for CNA and NetB were selected based on their affinity and specificity to develop sandwich enzyme-linked immunosorbent assays (ELISAs) to detect CNA and NetB proteins, respectively, in jejunal digesta samples from commercial broiler farms in the United States. Prior to the analysis of samples from commercial broiler flocks, the specificity and sensitivity of the CNA and NetB ELISAs were validated using sera, jejunal digesta, and fecal samples from chickens coinfected with Eimeria maxima and CNA+/NetB+C. perfringens in an animal model of necrotic enteritis (NE). Subsequently, a total of 251 field samples were collected from 74 commercial poultry farms. Among these, 18 samples were from 6 broiler farms that used certified organics (CO), and 155 samples were from 42 farms with nonantibiotics (NA). In jejunal digesta samples, CNA levels ranged from 0.02 to 0.59 ng/mL and NetB levels ranged from 0.09 to 1.91 ng/mL. CNA and NetB levels showed a positive correlation with each other (Pearson correlation coefficient r = 0.772, P < 0.001). CNA and NetB levels in jejunal digesta were significantly decreased in CO farms compared with those from NA farms (P < 0.001). In conclusion, these new C. perfringens antigen-specific sandwich ELISAs offer a sensitive and specific means to detect C. perfringens CNA and NetB proteins as biomarkers of early NE occurrence in field samples from commercial broiler chickens.

Characterizing ruminal acidosis risk: A multiherd, multicountry study

A multicenter observational study was conducted on early lactation Holstein cows (n = 261) from 32 herds from 3 regions (Australia, AU; California, CA; and Canada, CAN) to characterize their risk of acidosis into 3 groups (high, medium, or low) using a discriminant analysis model previously developed. Diets ranged from pasture supplemented with concentrates to total mixed ration (nonfiber carbohydrates = 17 to 47 and neutral detergent fiber = 27 to 58% of dry matter). Rumen fluid samples were collected <3 h after feeding and analyzed for pH, and ammonia, d- and l-lactate, and volatile fatty acid (VFA) concentrations. Eigenvectors were produced using cluster and discriminant analysis from a combination of rumen pH, and ammonia, d-lactate, and individual VFA concentrations and were used to calculate the probability of the risk of ruminal acidosis based on proximity to the centroid of 3 clusters. Bacterial 16S ribosomal DNA sequence data were analyzed to characterize bacteria. Individual cow milk volume, fat, protein, and somatic cell count values were obtained from the closest herd test to the rumen sampling date (median = 1 d before rumen sampling). Mixed model analyses were performed on the markers of rumen fermentation, production characteristics, and the probability of acidosis. A total of 26.1% of the cows were classified as high risk for acidosis, 26.8% as medium risk, and 47.1% as low risk. Acidosis risk differed among regions with AU (37.2%) and CA (39.2%) having similar prevalence of high-risk cows and CAN only 5.2%. The high-risk group had rumen phyla, fermentation, and production characteristics consistent with a model of acidosis that reflected a rapid rate of carbohydrate fermentation. Namely, acetate to propionate ratio (1.98 ± 0.11), concentrations of valerate (2.93 ± 0.14 mM), milk fat to protein ratio (1.11 ± 0.047), and a positive association with abundance of phylum Firmicutes. The medium-risk group contains cows that may be inappetant or that had not eaten recently or were in recovery from acidosis. The low-risk group may represent cattle that are well fed with a stable rumen and a slower rumen fermentation of carbohydrates. The high risk for acidosis group had lower diversity of bacteria than the other groups, whereas CAN had a greater diversity than AU and CA. Rumen fermentation profile, abundance of ruminal bacterial phyla, and production characteristics of early lactation dairy cattle from 3 regions were successfully categorized in 3 different acidosis risk states, with characteristics differing between acidosis risk groups. The prevalence of acidosis risk also differed between regions.

Survey of clinical and commensal Escherichia coli from commercial broilers and turkeys, with emphasis on high-risk clones using APECTyper

Molecular characterization of avian pathogenic Escherichia coli (APEC) is challenging due to the complex nature of its associated disease, colibacillosis, in poultry. Numerous efforts have been made toward defining APEC, and it is becoming clear that certain clonal backgrounds are predictive of an avian E. coli isolate's virulence potential. Thus, APEC can be further differentiated as high-risk APEC based upon their clonal background's virulence potential. However, less clear is the degree of overlap between clinical isolates of differing bird type, and between clinical and gastrointestinal isolates. This study aimed to determine genomic similarities and differences between such populations, comparing commercial broiler vs. turkey isolates, and clinical vs. gastrointestinal isolates. Differences were observed in Clermont phylogenetic groups between isolate populations, with B2 as the dominant group in turkey clinical isolates and G as the dominant group in broiler clinical isolates. Nearly all clinical isolates were classified as APEC using a traditional gene-based typing scheme, whereas 53.4% and 44.1% of broiler and turkey gastrointestinal isolates were classified as APEC, respectively. High-risk APEC were identified among 31.0% and 46.9% of broiler and turkey clinical isolates, compared with 5.7% and 2.9% of broiler and turkey gastrointestinal isolates. As found in previous studies, no specific known virulence or fitness gene sets were identified which universally differentiate between clinical and gastrointestinal isolates. This study further demonstrates the utility of a hybrid APEC typing approach, considering both plasmid content and clonal background, for the identification of dominant and highly virulent APEC clones in poultry production.

Associations among the genome, rumen metabolome, ruminal bacteria, and milk production in early-lactation Holsteins

A multicenter observational study to evaluate genome-wide association was conducted in early-lactation Holstein cows (n = 293) from 36 herds in Canada, the USA, and Australia. Phenotypic observations included rumen metabolome, acidosis risk, ruminal bacterial taxa, and milk composition and yield measures. Diets ranged from pasture supplemented with concentrates to total mixed rations (nonfiber carbohydrates = 17 to 47, and neutral detergent fiber = 27 to 58% of dry matter). Rumen samples were collected <3 h after feeding and analyzed for pH, ammonia, d- and l-lactate, volatile fatty acid (VFA) concentrations, and abundance of bacterial phyla and families. Eigenvectors were produced using cluster and discriminant analyses from a combination of pH and ammonia, d-lactate, and VFA concentrations, and were used to estimate the probability of the risk of ruminal acidosis based on proximity to the centroid of 3 clusters, termed high (24.0% of cows), medium (24.2%), and low risk (51.8%) for acidosis. DNA of sufficient quality was successfully extracted from whole blood (218 cows) or hair (65 cows) collected simultaneously with the rumen samples and sequenced using the Geneseek Genomic Profiler Bovine 150K Illumina SNPchip. Genome-wide association used an additive model and linear regression with principal component analysis (PCA) population stratification and a Bonferroni correction for multiple comparisons. Population structure was visualized using PCA plots. Single genomic markers were associated with milk protein percent and the center logged ratio abundance of the phyla Chloroflexi, SR1, and Spirochaetes, and tended to be associated with milk fat yield, rumen acetate, butyrate, and isovalerate concentrations and with the probability of being in the low-risk acidosis group. More than one genomic marker was associated or tended to be associated with rumen isobutyrate and caproate concentrations, and the center log ratio of the phyla Bacteroidetes and Firmicutes and center log ratio of the families Prevotellaceae, BS11, S24-7, Acidaminococcaceae, Carnobacteriaceae, Lactobacillaceae, Leuconostocaceae, and Streptococcaceae. The provisional NTN4 gene, involved in several functions, had pleiotropy with 10 bacterial families, the phyla Bacteroidetes and Firmicutes, and butyrate. The ATP2CA1 gene, involved in the ATPase secretory pathway for Ca²⁺ transport, overlapped for the families Prevotellaceae, S24-7, and Streptococcaceae, the phylum Bacteroidetes, and isobutyrate. No genomic markers were associated with milk yield, fat percentage, protein yield, total solids, energy-corrected milk, somatic cell count, rumen pH, ammonia, propionate, valerate, total VFA, and d-, l-, or total lactate concentrations, or probability of being in the high- or medium-risk acidosis groups. Genome-wide associations with the rumen metabolome, microbial taxa, and milk composition were present across a wide geographical and management range of herds, suggesting the existence of markers for the rumen environment but not for acidosis susceptibility. The variation in pathogenesis of ruminal acidosis in the small population of cattle in the high risk for acidosis group and the dynamic nature of the rumen as cows cycle through a bout of acidosis may have precluded the identification of markers for acidosis susceptibility. Despite a limited sample size, this study provides evidence of interactions between the mammalian genome, the rumen metabolome, ruminal bacteria, and milk protein percentage.

Gut Microbiota-Derived Indole-3-Carboxylate Influences Mucosal Integrity and Immunity Through the Activation of the Aryl Hydrocarbon Receptors and Nutrient Transporters in Broiler Chickens Challenged With Eimeria maxima

Two studies were conducted to evaluate the effects of indole-3-carboxylate (ICOOH) as a postbiotic on maintaining intestinal homeostasis against avian coccidiosis. In the first study, an in vitro culture system was used to investigate the effects of ICOOH on the proinflammatory cytokine response of chicken macrophage cells (CMCs), gut integrity of chicken intestinal epithelial cells (IECs), differentiation of quail muscle cells (QMCs), and primary chicken embryonic muscle cells (PMCs) and anti-parasitic effect against Eimeria maxima. Cells to be tested were seeded in the 24-well plates and treated with ICOOH at concentrations of 0.1, 1.0, and 10.0 µg. CMCs were first stimulated by lipopolysaccharide (LPS) to induce an innate immune response, and QMCs and PMCs were treated with 0.5% and 2% fetal bovine serum, respectively, before they were treated with ICOOH. After 18 h of incubation, cells were harvested, and RT-PCR was performed to measure gene expression of proinflammatory cytokines of CMCs, tight junction (TJ) proteins of IECs, and muscle cell growth markers of QMCs and PMCs. In the second study, in vivo trials were carried out to study the effect of dietary ICOOH on disease parameters in broiler chickens infected with E. maxima. One hundred twenty male broiler chickens (0-day-old) were allocated into the following four treatment groups: 1) basal diet without infection (CON), 2) basal diet with E. maxima (NC), 3) ICOOH at 10.0 mg/kg feed with E. maxima (HI), and 4) ICOOH at 1.0 mg/kg feed with E. maxima (LO). Body weights (BWs) were measured on 0, 7, 14, 20, and 22 days. All groups except the CON chickens were orally infected with E. maxima on day 14. Jejunal samples were collected for lesion score and the transcriptomic analysis of cytokines and TJ proteins. In vitro, ICOOH increased the expression of TJ proteins in IECs and decreased IL-1β and IL-8 transcripts in the LPS-stimulated CMCs. In vivo, chickens on the HI diet showed reduced jejunal IL-1β, IFN-γ, and IL-10 expression and increased expression of genes activated by aryl hydrocarbon receptors and nutrient transporters in E. maxima-infected chickens. In conclusion, these results demonstrate the beneficial effects of dietary ICOOH on intestinal immune responses and barrier integrity in broiler chickens challenged with E. maxima. Furthermore, the present finding supports the notion to use microbial metabolites as novel feed additives to enhance resilience in animal agriculture.

Comparative Genomics of Clostridium perfringens Reveals Patterns of Host-Associated Phylogenetic Clades and Virulence Factors

Clostridium perfringens is an opportunistic pathogenic bacterium that infects both animals and humans. Clostridium perfringens genomes encode a diverse array of toxins and virulence proteins, which continues to expand as more genomes are sequenced. In this study, the genomes of 44 C. perfringens strains isolated from intestinal sections of diseased cattle and from broiler chickens from diseased and healthy flocks were sequenced. These newly assembled genomes were compared to 141 publicly available C. perfringens genome assemblies, by aligning known toxin and virulence protein sequences in the assemblies using BLASTp. The genes for alpha toxin, collagenase, a sialidase (nanH), and alpha-clostripain were present in at least 99% of assemblies analyzed. In contrast, beta toxin, epsilon toxin, iota toxin, and binary enterotoxin of toxinotypes B, C, D, and E were present in less than 5% of assemblies analyzed. Additional sequence variants of beta2 toxin were detected, some of which were missing the leader or signal peptide sequences and therefore likely not secreted. Some pore-forming toxins involved in intestinal diseases were host-associated, the netB gene was only found in avian isolates, while netE, netF, and netG were only present in canine and equine isolates. Alveolysin was positively associated with canine and equine strains and only present in a single monophyletic clade. Strains from ruminant were not associated with known virulence factors and, except for the food poisoning associated clade, were present across the phylogenetic diversity identified to date for C. perfringens. Many C. perfringens strains associated with food poisoning lacked the genes for hyaluronidases and sialidases, important for attaching to and digesting complex carbohydrates found in animal tissues. Overall, the diversity of virulence factors in C. perfringens makes these species capable of causing disease in a wide variety of hosts and niches.

Effects of Dietary Maltol on Innate Immunity, Gut Health, and Growth Performance of Broiler Chickens Challenged With Eimeria maxima

Two studies were conducted to evaluate the effects of maltol as a postbiotic on innate immunity, gut health, and enteric infection. In the first study, an in vitro culture system was used to evaluate the effects of maltol on the innate immune response of chicken macrophage cells (CMC), gut integrity of chicken intestinal epithelial cells (IEC), anti-parasitic activity against Eimeria maxima, and differentiation of quail muscle cells (QMC) and primary chicken embryonic muscle cells (PMC). All cells seeded in the 24-well plates were treated with maltol at concentrations of 0.1, 1.0, and 10.0 μg. CMC and IEC were stimulated by lipopolysaccharide to induce an innate immune response, and QMC and PMC were treated with 0.5 and 2% fetal bovine serum, respectively. After 18 h of incubation, pro-inflammatory cytokines, tight junction proteins (TJPs), and muscle cell growth markers were measured. In the second study, the dietary effect of maltol was evaluated on disease parameters in broiler chickens infected with E. maxima. Eighty male 1-day-old broiler chickens were allocated into the following four treatment groups: (1) Control group without infection, (2) Basal diet with E. maxima, (3) High maltol (HI; 10.0 mg /kg feed) with E. maxima, and (4) Low maltol (LO; 1.0 mg/kg feed) with E. maxima. Body weights (BW) were measured on days 0, 7, 14, 20, and 22. All chickens except the CON group were orally infected with 10⁴E. maxima per chicken on day 14. Jejunum samples were collected for gut lesion scoring, and the gene expression of cytokines and TJPs. Data was analyzed using PROC MIXED in SAS. In vitro, maltol not only increased TJPs in IEC and cytokines in the LPS-stimulated CMC but also showed direct cytotoxicity against sporozoites of E. maxima. In vivo, the HI group improved the BW, reduced the gut lesion scores and fecal oocyst shedding, and decreased jejunal TNFSF15 and IL-1β expression in E. maxima-infected chickens. In conclusion, these results demonstrate the beneficial effects of dietary maltol in the enhancement of growth performance, gut health, and coccidiosis resistance and the applicability of maltol as a postbiotic for the replacement of antibiotic growth promoters in commercial poultry production.

Dietary Supplementation With Bacillus subtilis Direct-Fed Microbials Alters Chicken Intestinal Metabolite Levels

Direct-fed microbials (DFMs) are dietary supplements containing live microorganisms which confer a performance and health benefit to the host, but the mechanisms are unclear. Here, a metabolomics approach was used to identify changes in intestinal metabolite levels in chickens fed an unsupplemented diet or a diet supplemented with B. subtilis strain 1781 or strain 747. Body weight gains of chickens fed the B. subtilis-supplemented diets were increased up to 5.6% in the B. subtilis 1781 group and 7.6% in the B. subtilis 747 group compared with chickens fed the unsupplemented diet. Compared with unsupplemented controls, the levels of 83 metabolites were altered (p < 0.05) (25 increased, 58 decreased) in chickens given the B. subtilis 1781-supplemented diet, while 50 were altered (p < 0.05) (12 increased, 38 decreased) with the B. subtilis 747-supplemented diet. Twenty-two metabolites were altered (p < 0.05) (18 increased, 4 decreased) in the B. subtilis 1781 vs. B. subtilis 747 groups. A random forest analysis of the B. subtilis 1781 vs. control groups gave a predictive accuracy of 87.5%, while that of the B. subtilis 747 vs. control groups was 62.5%. A random forest analysis of the B. subtilis 1781 vs. B. subtilis 747 groups gave a predictive accuracy of 75.0%. Changes in the levels of these intestinal biochemicals provided a distinctive biochemical signature unique to each B. subtilis-supplemented group, and were characterized by alterations in the levels of dipeptides (alanylleucine, glutaminylleucine, phenylalanylalanine, valylglutamine), nucleosides (N1-methyladenosine, N6-methyladenosine, guanine, 2-deoxyguanosine), fatty acids (sebacate, valerylglycine, linoleoylcholine), and carbohydrates (fructose). These results provide the foundation for future studies to identify biochemicals that might be used to improve poultry growth performance in the absence of antibiotic growth promoters.

The effects of dietary Bacillus subtilis supplementation, as an alternative to antibiotics, on growth performance, intestinal immunity, and epithelial barrier integrity in broiler chickens infected with Eimeria maxima

The objective of this study was to investigate the effects of dietary Bacillus subtilis supplementation on growth performance, jejunal lesion scores, oocyst shedding, and cytokine and tight junction protein expression in broiler chickens infected with Eimeria maxima. A total of 196 male day-old Ross 708 broilers were given a nonexperimental diet until 14 D of age. Then, all chickens were randomly assigned to one of seven dietary treatments: 2 basal diets (CON and NC); CON + virginiamycin (AB1); CON + bacitracin methylene disalicylate (BMD; AB2); CON + B. subtilis 1781 (PB1); CON + B. subtilis 747 (PB2); or CON + B. subtilis 1781 + 747 (PB3). At day 21, all chickens except those in the CON group were orally inoculated with E. maxima oocysts. At 7 D after E. maxima infection, the body weight gains of chickens fed PB2 and PB3 increased (P = 0.032) as much as those in chickens fed AB2. The body weight gain and feed efficiency of chickens fed PB2 were significantly increased (P < 0.001), and PB2 chickens showed (P = 0.005) the lowest lesion scores after E. maxima infection. Chickens fed PB2 showed (P < 0.05) lower mRNA expression of IL-1β in infected chicken groups. Chickens in the AB1, AB2, PB1, PB2, and PB3 groups showed (P < 0.05) greater mRNA expression of junctional adhesion molecule 2 in jejunal tissue, whereas occludin expression increased (P < 0.05) in the jejunal tissue of chickens fed AB2 or PB2. Dietary B. subtilis supplementation significantly improved the growth performance of young chickens to a level comparable with that induced by virginiamycin or BMD without E. maxima infection. After infection with E. maxima, dietary virginiamycin and BMD significantly enhanced the epithelial barrier integrity, and the dietary B. subtilis 747 showed significantly enhanced growth performance, intestinal immunity, and epithelial barrier integrity. Together our results indicated that certain strains of B. subtilis provide beneficial effects on the growth of young broiler chickens and have the potential to replace antibiotic growth promoters.

Bacteria and fungi in day-old turkeys vary among companies, collection periods, and breeder flocks

Microbial colonization of the intestinal tract of commercial poultry is highly variable, likely due to the fact that poults and chicks are hatched and raised without exposure to adult birds and their microbiota. In industrial poultry production, it is hypothesized that most of the microbiota is obtained through horizontal transmission from the environment and very little by maternal transmission. The initial gut microbiota will therefore differ between flocks and companies based on environmental conditions at the hatchery. Day-old poults were collected from the hatchery of 2 companies at 3 different time points to monitor the initial colonizing microbiota by sequencing amplicons of marker genes for bacteria, lactic acid bacteria (LAB), fungi, and archaea. Bacterial colonizers were distinct by company (pseudo-F 38.7, P ≤ 0.05) with the predominant bacteria at Company A being clostridia, specifically Clostridium celatum group, C. paraputrificum, and C. tertium. Predominant bacteria at Company B were Enterobacteriaceae, belonging to 2 different groups, one that included Escherichia; Shigella and Salmonella and the other Klebsiella; Enterobacter; and others. The predominant LAB at both companies were Enterococcus faecalis and E. gallinarum, confirmed by sequencing the 16S ribosomal RNA (rRNA) gene of colonies picked from lactobacilli agar plate counts. The predominant fungi were Aspergillus niger and Saccharomyces cerevisiae, with Candida sake or Alterneria sp. in some samples of Company A. Archaeal sequences were detected only in a single poult from Company B. The initial gastrointestinal colonizers of poults vary across company and time, signifying a strong environmental effect on microbiota acquisition. There was an indication of maternal effects in certain breeder flocks from Company B. Further work is necessary to determine how this variability affects microbiota succession and impacts growth and production of the birds.

Breast Cancer Diagnosis under the Age of Forty Years

The authors report on a multicentric consecutive series of 382 cases of primary breast cancer detected before the age of 40 years. Physical examination (PE) was always performed, whereas other diagnostic tests were performed in selected cases, namely mammography (M) in 334, fine needle aspiration cytology (CYT) in 188 and thermography (TH) in 123 cases. Single tests showed a high rate of false-negative/benign cases (PE, 0.23; M, 0.26; CYT, 0.37 and TH, 0.50), especially when the T1 subgroup was considered (PE, 0.34; M, 0.38; CYT, 0.42 and TH, 0.78). The poor results recorded for TH make its current diagnostic use highly questionable. The policy of extensive biopsy of all « dubious » benign lesions on PE allowed for the detection of 41 of 382 cancers and reduced the PE false-negative/benign rate to 0.12 for the total or 0.15 for T1 cancers, although about 80 unnecessary biopsies for each cancer detected were performed in this way. The association of PE to one or more tests resulted in even lower false-negative rates (0.06 for the total, 0.10 for T1 cancers). The authors criticize the aggressive policy of extensive biopsy recommendation based only on a dubious report on PE alone and stress the opportunity of the routine association of M and CYT to PE, since this combination seems to achieve a higher breast cancer detection rate even in this age group.

SorCS2 is required for BDNF-dependent plasticity in the hippocampus

SorCS2 is a member of the Vps10p-domain receptor gene family receptors with critical roles in the control of neuronal viability and function. Several genetic studies have suggested SORCS2 to confer risk of bipolar disorder, schizophrenia and attention deficit-hyperactivity disorder. Here we report that hippocampal N-methyl-d-aspartate receptor-dependent synaptic plasticity is eliminated in SorCS2-deficient mice. This defect was traced to the ability of SorCS2 to form complexes with the neurotrophin receptor p75NTR, required for pro-brain-derived neurotrophic factor (BDNF) to induce long-term depression, and with the BDNF receptor tyrosine kinase TrkB to elicit long-term potentiation. Although the interaction with p75NTR was static, SorCS2 bound to TrkB in an activity-dependent manner to facilitate its translocation to postsynaptic densities for synaptic tagging and maintenance of synaptic potentiation. Neurons lacking SorCS2 failed to respond to BDNF by TrkB autophosphorylation, and activation of downstream signaling cascades, impacting neurite outgrowth and spine formation. Accordingly, Sorcs2-/- mice displayed impaired formation of long-term memory, increased risk taking and stimulus seeking behavior, enhanced susceptibility to stress and impaired prepulse inhibition. Our results identify SorCS2 as an indispensable coreceptor for p75NTR and TrkB in hippocampal neurons and suggest SORCS2 as the link between proBDNF/BDNF signaling and mental disorders.

A direct comparison of endothelial progenitor cell dysfunction in rat metabolic syndrome and diabetes

OBJECTIVES

Diabetes mellitus (DM) is associated with impairment of endothelial progenitor cells (EPCs), but the effects of metabolic syndrome (MS) on EPCs have been less well characterized. We hypothesized that in the presence of MS, the number and functionality of EPCs would be markedly reduced, and would be similar to DM.

METHODS

Mononuclear cells were isolated from the bone-marrow (BM) and peripheral blood of lean Zucker, obese Zucker, a model of MS, and Zucker diabetic fatty rats. Cultured BM-EPCs underwent in vitro functional testing and the ability of BM-EPCs to promote neovascularization in vivo was assessed in a model of hindlimb ischemia in athymic mice.

RESULTS

While circulating EPC numbers were similarly reduced in both MS and DM rats, BM-derived EPC numbers were less affected. In vitro testing of cultured BM-EPCs from obese Zucker demonstrated a marked reduction in EPC differentiation, a greater propensity to apoptosis, a reduced migratory response and matrigel tubule formation, similar to findings in Zucker diabetic fatty rats. When delivered to the ischemic hindlimb of athymic mice, the recovery of perfusion using both BM-EPCs from obese Zucker and Zucker diabetic fatty rats were diminished, as compared to lean Zuckers.

CONCLUSION

In the presence of the MS, BM-derived EPCs develop marked functional impairment, resulting in severely reduced angiogenic capacity in vivo. Similar to DM, EPC dysfunction may play a prominent role in the pathogenesis of vascular complications in the MS, and may potentially limit the use of BM-derived EPCs for therapeutic angiogenesis.

Red blood cell transfusion volume and mortality among patients receiving extracorporeal membrane oxygenation

Background:

Red blood cell (RBC) transfusion is used in the critically ill with low hemoglobin concentrations to optimize oxygen utilization and delivery imbalance. Data suggest that RBC transfusion is also independently associated with significant morbidity. We seek to characterize RBC transfusion volumes among patients receiving extracorporeal membrane oxygenation (ECMO) support and test the hypothesis that red blood cell transfusion volume is an independent risk factor for mortality.

Methods:

Records of all patients receiving ECMO support from 2001 through 2010 at a university-affiliated children’s hospital were retrospectively reviewed.

Results:

Among 484 ECMO runs reviewed, indications for ECMO were classified as cardiac (40%), non-cardiac (42%) or institution of ECMO during cardiopulmonary resuscitation (CPR) (18%). Median duration of ECMO support was 4.6 days, with overall survival to hospital discharge significantly higher among non-cardiac patients (60%) relative to patients supported for cardiac (37%) or external CPR (ECPR) indications (34%, p<0.001). Median RBC transfusion volumes with respect to ECMO indication were significantly greater among cardiac (105 mL/kg/day ECMO) and ECPR patients (66 mL/kg/day ECMO) relative to patients supported for non-cardiac indications (20 mL/kg/day ECMO, p<0.001). Among patients supported with ECMO for non-cardiac indications alone (n=203), independent of covariates, including weight, venoarterial mode of ECMO support, presence of congenital diaphragmatic hernia and complications, including hemorrhage, neurologic injury, and renal insufficiency, each RBC transfusion volume of 10 mL/kg/day ECMO was associated with a 24% increase in the odds of in-hospital mortality (OR 1.024, 95% CI 1.004-1.046, p=0.018).

Conclusions:

Greater red blood cell transfusion volumes among patients supported with ECMO for non-cardiac indications are independently associated with an increase in odds of mortality. A prospective investigation of restrictive RBC transfusion practices while receiving ECMO may be warranted in this population.

Sustained improvement in perfusion and flow reserve after temporally separated delivery of vascular endothelial growth factor and angiopoietin-1 plasmid deoxyribonucleic acid

OBJECTIVES

The aim of this study was to compare temporally separated vascular endothelial growth factor (VEGF) and angiopoietin (Ang)-1 delivery with concomitant delivery or single VEGF delivery, for therapeutic angiogenesis in chronic ischemia.

BACKGROUND

Single gene delivery of VEGF results in immature neovessels that ultimately regress. Endogenously, VEGF acts early to initiate angiogenesis, whereas Ang-1 acts later to induce vessel maturation. Timing VEGF and Ang-1 gene delivery to mimic endogenous angiogenesis might be more effective for sustained neovascularization.

METHODS

Unilateral hindlimb ischemia was induced in 170 rats. Ultrasound-mediated gene delivery was performed with cationic microbubbles and plasmid deoxyribonucleic acid. Groups included VEGF at 2 weeks, VEGF/Ang-1 at 2 weeks, VEGF at 2 weeks with Ang-1 at 4 weeks, and untreated control subjects. At 2, 4, and 8 weeks after ligation, blood flow and flow reserve (FR) were assessed by contrast-enhanced ultrasound. Vascular density, organization, and supporting cell coverage were assessed by fluorescent microangiography and immunohistochemistry.

RESULTS

In untreated control subjects, blood flow, FR, and vessel density remained reduced. The VEGF delivery improved flow and vessel density at 4 weeks; however, FR remained low, supporting cell coverage was poor, and flow and vessel density regressed by 8 weeks. The VEGF/Ang-1 co-delivery marginally increased flow and vessel density; however, FR and supporting cell coverage improved. After temporally separated VEGF and Ang-1 delivery, blood flow, vessel density, and FR increased and were sustained, with improved pericyte coverage at 8 weeks.

CONCLUSIONS

In conclusion, temporally separated VEGF and Ang-1 gene therapy results in sustained and functional neovascularization.

Stem Cell Therapy: A New Treatment for Burns?

Stem cell therapy has emerged as a promising new approach in almost every medicine specialty. This vast, heterogeneous family of cells are now both naturally (embryonic and adult stem cells) or artificially obtained (induced pluripotent stem cells or iPSCs) and their fates have become increasingly controllable, thanks to ongoing research in this passionate new field. We are at the beginning of a new era in medicine, with multiple applications for stem cell therapy, not only as a monotherapy, but also as an adjunct to other strategies, such as organ transplantation or standard drug treatment. Regrettably, serious preclinical concerns remain and differentiation, cell fusion, senescence and signalling crosstalk with growth factors and biomaterials are still challenges for this promising multidisciplinary therapeutic modality. Severe burns have several indications for stem cell therapy, including enhancement of wound healing, replacement of damaged skin and perfect skin regeneration – incorporating skin appendages and reduced fibrosis –, as well as systemic effects, such as inflammation, hypermetabolism and immunosuppression. The aim of this review is to describe well established characteristics of stem cells and to delineate new advances in the stem cell field, in the context of burn injury and wound healing.

DIET AND TISSUE GROWTH : I. THE REGENERATION OF LIVER TISSUE ON VARIOUS ADEQUATE DIETS

1. The toxicity of chloroform varies according to the diets used in these experiments in the following order of decreasing susceptibility of the animals: high fat > standard > high carbohydrate > high protein diets. 2. On the high fat and high carbohydrate diets there may be a more or less marked proliferation of the endothelium and the connective tissue stroma in the necrotic area producing in some instances scars resembling the picture of an early cirrhosis. 3. On the diets studied, standard, high carbohydrate, high protein, and high fat, the most active and rapid repair is observed on the standard balanced diet. On the high fat diet the reparative process is definitely delayed in comparison with the others. There are only slight differences between the high carbohydrate and high protein diets which suggest but do not conclusively show a more rapid repair with the latter diet.

DIET AND TISSUE GROWTH : IV. THE RATE OF COMPENSATORY RENAL ENLARGEMENT AFTER UNILATERAL NEPHRECTOMY IN THE WHITE RAT

The rate of compensatory enlargement of the remaining kidney after unilateral nephrectomy has been studied in adult rats fed diets containing various concentrations of protein. A curve of enlargement on "standard" food (18 per cent casein) shows a rapid initial increase with subsequent slower rise to the 120th day. There is no significant difference between the value at 120 days (44 per cent) and that at 150 days (48 per cent). A similar series with diets containing increasing concentrations of protein but with a constant time interval (21 days) after nephrectomy shows an increase in the degree of enlargement directly proportional to the protein content of the food. The values vary from 24 per cent with the 18 per cent casein ration to 77 per cent with the 90 per cent casein diet. A third series shows the enlargement on "high protein" food (85 per cent casein). The values vary from 49 per cent at 3 days to 121 per cent at 150 days. There is no significant difference between the value at 120 days (123 per cent) and that at 150 days (121 per cent). Determinations of total solids on the experimental kidneys show that the recorded enlargement involves mainly an actual tissue increase.

DIET AND TISSUE GROWTH : V. THE EFFECT OF DIETARY PROTEIN ON THE REMAINING KIDNEY OF ADULT WHITE RATS FOLLOWING A UNILATERAL NEPHRECTOMY

The effects of the ingestion of diets containing different concentrations of protein on the remaining kidney in adult white rats after a unilateral nephrectomy has been studied. In the animals on the high protein diet (85 per cent casein), actual glomerular and tubular lesions were observed in the kidneys of animals maintained for 90, 120 and 150 days after nephrectomy. In the animals on the standard ration, 18 per cent casein, no significant renal lesions were observed within the experimental period. Spontaneous focal lesions in the kidneys of rats maintained on Sherman's diets "A" and "B" were inconspicuous at the age of 350 days but became progressively more frequent and were commonly observed after 500 days. The animals on the high protein and standard rations were all under 350 days old at the completion of the experiment. It is suggested that the age factor is of importance in that young animals may have greater powers of adaptation in withstanding the injurious effect of high protein rations. The animals on the high protein ration excreted definitely larger quantities of protein in the urine, and showed a higher incidence of casts in periods roughly corresponding to those in which anatomic lesions were observed than did the rats on the standard diet.

DIET AND TISSUE GROWTH : II. THE REGENERATION OF LIVER TISSUE DURING NUTRITION ON INADEQUATE DIETS AND FASTING

The relative toxicity of chloroform given subcutaneously to rats fed on two diets deficient in respect to their nitrogenous components, the sole sources of protein in which were, respectively, gliadin and gelatin and to rats without food, is as follows: gelatin diet > fasting > gliadin diet. The rate of regeneration of liver cells after chloroform poisoning in rats fed a diet in which gliadin is the only protein is about as rapid as that in animals fed a diet containing casein as the source of nitrogen. The rate of regeneration on a food containing its nitrogen as gelatin and also during fasting is definitely slower than that in animals fed the gliadin food. The results of these experiments indicate that the requirement for the essential amino acids for growth of individual organs of the body is less than that for correlated growth of the whole body.

Improved methods and standards for telomerase detection: quantitative histopathology using antibody staining

Evaluation of telomerase as an early detection biomarker for cancer has been hindered by a lack of reliable methods and standards for in situ histochemical measurement. Improved histochemical methods for measuring telomerase could expedite the acceptance of telomerase as a biomarker for use in diagnostic and clinical applications. The lack of a crystal structure for telomerase coupled with high variability in the antibodies available for immunohistochemical analysis has led to confusion in the literature regarding the binding specificity of these antibodies. We have developed an automated fluorescence microscopy protocol to assess the specificity of three fluorescently labeled telomerase antibodies and to quantify telomerase in cultured human tumor cells and in human fibroblast cells as a control. Significant differences in staining intensity and distribution were observed. Fluorescence measurements in these cell lines were compared to telomerase measured by the telomerase repeat amplification protocol, reverse transcription-polymerase chain reaction, and flow cytometry. This combination of measurements ensured a more complete quantitation of telomerase levels in each of the cell lines and could also be used as a model for validation of other biomarkers for clinical use.

Molecular imaging of endothelial progenitor cell engraftment using contrast-enhanced ultrasound and targeted microbubbles

AIMS

Imaging methods to track the fate of progenitor cells after their delivery would be useful in assessing the efficacy of cell-based therapies. We hypothesized that contrast-enhanced ultrasound (CEU) using microbubbles targeted to a genetically engineered cell-surface marker on endothelial progenitor cells (EPCs) would allow the targeted imaging of vascular engraftment.

METHODS AND RESULTS

Rodent bone marrow-derived EPCs were isolated, cultured, and transfected to express the marker protein, H-2Kk, on the cell surface. Non-transfected EPCs and EPCs transfected with either null plasmid or Firefly luciferase served as controls. Control microbubbles (MB(C)) and microbubbles targeted to H-2Kk expressed on EPCs (MB(H-2Kk)) were constructed. Binding of targeted microbubbles to EPCs was assessed in vitro using a parallel plate flow chamber system. CEU imaging of EPC-targeted microbubbles was assessed in vivo using subcutaneously implanted EPC-supplemented Matrigel plugs in rats. In flow chamber experiments, there was minimal attachment of microbubbles to plated control EPCs. Although numbers of adhered MB(C) were also low, there was greater and more diffuse attachment of MB(H-2Kk) to plated H-2Kk-transfected EPCs. Targeted CEU demonstrated marked contrast enhancement at the periphery of the H-2Kk-transfected EPC-supplemented Matrigel plug for MB(H-2Kk,) whereas contrast enhancement was low for MB(C). Contrast enhancement was also low for both microbubbles within control mock-transfected EPC plugs. The signal intensity within the H-2Kk-transfected EPC plug was significantly greater for MB(H-2Kk) when compared with MB(C).

CONCLUSION

Microbubbles targeted to a genetically engineered cell-surface marker on EPCs exhibit specific binding to EPCs in vitro. These targeted microbubbles bind to engrafted EPCs in vivo within Matrigel plugs and can be detected by their enhancement on CEU imaging.

Meta-analysis of benzene exposure and non-Hodgkin lymphoma: biases could mask an important association

OBJECTIVES

Benzene is a widely recognised cause of leukaemia but its association with non-Hodgkin's lymphoma (NHL) is less well established. The goal of this project is to review the current published literature on this association.

METHODS

We performed a meta-analysis of cohort and case-control studies of benzene exposure and NHL and a meta-analysis of NHL and refinery work, a potential source of benzene exposure.

RESULTS

In 22 studies of benzene exposure, the summary relative risk for NHL was 1.22 (95% CI 1.02 to 1.47; one-sided p value = 0.01). When studies that likely included unexposed subjects in the "exposed" group were excluded, the summary relative risk increased to 1.49 (95% CI 1.12 to 1.97, n = 13), and when studies based solely on self-reported work history were excluded, the relative risk rose to 2.12 (95% CI 1.11 to 4.02, n = 6). In refinery workers, the summary relative risk for NHL in all 21 studies was 1.21 (95% CI 1.00 to 1.46; p = 0.02). When adjusted for the healthy worker effect, this relative risk estimate increased to 1.42 (95% CI 1.19 to 1.69).

CONCLUSIONS

The finding of elevated relative risks in studies of both benzene exposure and refinery work provides further evidence that benzene exposure causes NHL. In addition, the finding of increased relative risks after removing studies that included unexposed or lesser exposed workers in "exposed" cohorts, and increased relative risk estimates after adjusting for the healthy worker effect, suggest that effects of benzene on NHL might be missed in occupational studies if these biases are not accounted for.

Development of Nested Polymerase Chain Reaction Detection of Mycosphaerella spp. and Its Application to the Study of Leaf Disease in Eucalyptus Plantations

ABSTRACT Mycosphaerella leaf disease (MLD) is a serious disease of two of the major eucalypt species grown in temperate regions worldwide, Eucalyptus globulus and E. nitens. More than 30 species of Mycosphaerella have been reported on eucalypts worldwide. Accurate, rapid, and early discrimination of Mycosphaerella spp. causing crown damage to E. globulus and E. nitens will assist the development of sustainable management strategies. This study describes the development, and incorporation in a nested polymerase chain reaction (PCR) approach, of specific primers for the detection and identification of Mycosphaerella spp. commonly reported from leaf lesions of E. globulus and E. nitens in Australia. Primer design was assisted by sequence alignment and phylogenetic analysis of 165 nonredundant sequences from the nuclear ribosomal DNA internal transcribed spacer regions of Mycosphaerella and related species. Phylo-genetic analysis revealed very high sequence similarity for two taxon groups, Mycosphaerella grandis and M. parva, and M. vespa, M. ambi phylla, and M. molleriana, and primers were designed to differentiate each of the two groups. Three other species, M. cryptica, M. nubilosa, and M. tasmaniensis, were distinct and distinguished by species-specific primers. In double-blind trials, the detection test accurately and rapidly identified Mycosphaerella spp. in cultures and discriminated against other pathogens that co-occur in or on Eucalyptus leaves, thereby verifying its reliability. The detection test has an internal amplification control in the first-round PCR with fungal-specific primers to raise confidence in test results, particularly to highlight negative results due to PCR inhibition. When applied to DNA extracted from leaf or stem samples either as multiple or single lesions, it detected and identified up to five Mycosphaerella spp. or taxon groups in both positively identified and in young (putative) MLD lesions. The samples were 20 mm(2) or larger in surface area and were collected while undertaking disease rating assessments in an experimental investigation of Eucalyptus plantations and regrowth forest. Using nested PCR detection, Mycosphaerella spp. were positively identified in 2 days, 1 to 5 months earlier than by classical methods, demonstrating the potential application of this detection test to the early discrimination of MLD components in ecological, epidemiological, and genetic investigations.

Adaptation of a luciferase gene reporter and lac expression system to Borrelia burgdorferi

The development of new genetic systems for studying the complex regulatory events that occur within Borrelia burgdorferi is an important goal of contemporary Lyme disease research. Although recent advancements have been made in the genetic manipulation of B. burgdorferi, there still remains a paucity of basic molecular systems for assessing differential gene expression in this pathogen. Herein, we describe the adaptation of two powerful genetic tools for use in B. burgdorferi. The first is a Photinus pyralis firefly luciferase gene reporter that was codon optimized to enhance translation in B. burgdorferi. Using this modified reporter, we demonstrated an increase in luciferase expression when B. burgdorferi transformed with a shuttle vector encoding the outer surface protein C (OspC) promoter fused to the luciferase reporter was cultivated in the presence of fresh rabbit blood. The second is a lac operator/repressor system that was optimized to achieve the tightest degree of regulation. Using the aforementioned luciferase reporter, we assessed the kinetics and maximal level of isopropyl-beta-D-thiogalactopyranoside (IPTG)-dependent gene expression. This lac-inducible expression system also was used to express the gene carried on lp25 required for borrelial persistence in ticks (bptA). These advancements should be generally applicable for assessing further the regulation of other genes potentially involved in virulence expression by B. burgdorferi.

Evidence that RpoS (sigmaS) in Borrelia burgdorferi is controlled directly by RpoN (sigma54/sigmaN)

The alternative sigma factor (RpoN-RpoS) pathway controls the expression of key virulence factors in Borrelia burgdorferi. However, evidence to support whether RpoN controls rpoS directly or, perhaps, indirectly via a transactivator has been lacking. Herein we provide biochemical and genetic evidence that RpoN directly controls rpoS in B. burgdorferi.

Pregnancy outcomes, infant mortality, and arsenic in drinking water in West Bengal, India

Between 2001 and 2003, the authors studied pregnancy outcomes and infant mortality among 202 married women in West Bengal, India. Reproductive histories were ascertained using structured interviews. Arsenic exposure during each pregnancy, including all water sources used, was assessed; this involved measurements from 409 wells. Odds ratios for spontaneous abortion, stillbirth, neonatal mortality, and infant mortality were estimated with logistic regression based on the method of generalized estimating equations. Exposure to high concentrations of arsenic (> or =200 microg/liter) during pregnancy was associated with a sixfold increased risk of stillbirth after adjustment for potential confounders (odds ratio (OR) = 6.07, 95% confidence interval (CI): 1.54, 24.0; p = 0.01). Arsenic-related skin lesions were found in 12 women who had a substantially increased risk of stillbirth (OR = 13.1, 95% CI: 3.17, 54.0; p = 0.002). The odds ratio for neonatal death was 2.81 (95% CI: 0.73, 10.8). No association was found between arsenic exposure and spontaneous abortion (OR = 1.01, 95% CI: 0.38, 2.70) or overall infant mortality (OR = 1.33, 95% CI: 0.43, 4.04). This study adds to the limited evidence that exposure to high concentrations of arsenic during pregnancy increases the risk of stillbirth. However, there was no indication of the increased rates of spontaneous abortion and overall infant mortality that have been reported in some studies.

Precision and accuracy of pest and pathogen damage assessment in young eucalypt plantations

Fungal pathogens, browsing mammals, birds, insects, nutrient deficiencies, drought, frost and waterlogging are all damaging agents to plantation species. The subsequent loss in leaf tissue or reduced photosynthetic potential can reduce growth and potentially lead to tree death. The Crown Damage Index (CDI) was developed in Australia to quantify damage in young eucalypt plantations. The accuracy and precision of assessing damage at a tree level were determined to ensure the reliability, objectivity and repeatability of the CDI method. Nine assessors, with varying levels of experience, estimated damage on three plots of fifty trees each, to obtain an understanding of the subjectivity of assessing damage caused by insects (e.g. Chrysophtharta spp.) and fungal pathogens (e.g. Mycosphaerella spp.) on Eucalyptus globulus. Damage levels were measured by destructive sampling to enable direct comparisons between estimates and damage levels to be made. The most experienced assessors provided the most repeatable estimates and were generally the most accurate. The incidence of foliar necrosis was the least subjective measure while defoliation was the most subjective and the least accurate of the indices measured. All assessors, regardless of experience, were able to predict the Crown Damage Index (a combined index of all damage classes) to within 12% of measured damage levels.

Bacterial mechanisms to overcome inhibitory effects of dietary tannins

High concentrations of tannins in fodder plants inhibit gastrointestinal bacteria and reduce ruminant performance. Increasing the proportion of tannin-resistant bacteria in the rumen protects ruminants from anti-nutritional effects. The reason for the protective effect is unclear, but could be elucidated if the mechanism(s) by which tannins inhibit bacteria and the mechanisms of tannin resistance were understood. A review of the literature indicates that the ability of tannins to complex with polymers and minerals is the basis of the inhibitory effect on gastrointestinal bacteria. Mechanisms by which bacteria can overcome inhibition include tannin modification/degradation, dissociation of tannin-substrate complexes, tannin inactivation by high-affinity binders, and membrane modification/repair and metal ion sequestration. Understanding the mechanism of action of tannins and the mechanism(s) bacteria use to overcome the inhibitory effects will allow better management of the rumen ecosystem to reduce the anti-nutritional effects of tannin-rich fodder plants and thereby improve ruminant production.

Effect of condensed tannins on bacterial diversity and metabolic activity in the rat gastrointestinal tract

The effect of dietary condensed tannins (proanthocyanidins) on rat fecal bacterial populations was ascertained in order to determine whether the proportion on tannin-resistant bacteria increased and if there was a change in the predominant bacterial populations. After 3 weeks of tannin diets the proportion of tannin-resistant bacteria increased significantly (P < 0.05) from 0.3% +/- 5.5% to 25.3% +/- 8.3% with a 0.7% tannin diet and to 47.2% +/- 5.1% with a 2% tannin diet. The proportion of tannin-resistant bacteria returned to preexposure levels in the absence of dietary tannins. A shift in bacterial populations was confirmed by molecular fingerprinting of fecal bacterial populations by denaturing gradient gel electrophoresis (DGGE). Posttreatment samples were generally still distinguishable from controls after 3.5 weeks. Sequence analysis of DGGE bands and characterization of tannin-resistant isolates indicated that tannins selected for Enterobacteriaceae and Bacteroides species. Dot blot quantification confirmed that these gram-negative bacterial groups predominated in the presence of dietary tannins and that there was a corresponding decrease in the gram-positive Clostridium leptum group and other groups. Metabolic fingerprint patterns revealed that functional activities of culturable fecal bacteria were affected by the presence of tannins. Condensed tannins of Acacia angustissima altered fecal bacterial populations in the rat gastrointestinal tract, resulting in a shift in the predominant bacteria towards tannin-resistant gram-negative Enterobacteriaceae and Bacteroides species.

Cross-calibration of GE/Lunar pencil and fan-beam dual energy densitometers--bone mineral density and body composition studies

OBJECTIVE

In vitro and in vivo comparisons of bone mineral density (BMD) and body composition between GE/Lunar pencil (DPXL) and fan-beam (PRODIGY) absorptiometers.

DESIGN

Comparison of BMD, bone mineral content (BMC) and area of lumbar spine (L2-L4), femoral neck and total body. Total body composition compartments tissue (TBTissue), fat (TBF), lean tissue (TBLean) and %TBF were also compared.

SETTING

Centre for Bone and Body Composition Research, University of Leeds. PHANTOMS/SUBJECTS: A range of spine phantoms, a variable composition phantom (VCP) and total body phantom. A total of 72 subjects were included for the in vivo study.

RESULTS

In vitro: A small significant underestimation of BMD by the Prodigy compared to the DPXL ranging from 0.7 to 2% (p<0.05-0.001) for the spine phantoms. The Prodigy underestimated the VCP %Fat. Although the Prodigy underestimated phantom TBBMD by 1.1+/-1.0%, TBBMC and area were reduced by 8.2+/-1.4 and 7.3+/-1.0%, respectively. The Prodigy overestimated TBTissue 1508 g (2.2%), TBLean 588 g (1.2%), TBF 919 g (4.8%) and %TBF (0.8%). In vivo: BMD cross-calibration was only required in the femoral neck, DPXL(BMD)=0.08+0.906*PRODIGY(BMD). The Prodigy had higher estimates for TBTissue 1360 g (2.3%), TBLean 840 g (2.0%), TBF 519 g (3.4%), TBBMC 32.8 g (1.3%) and %TBF (0.3%). Cross-calibration equations were required for TBTissue(DPXL)=-1158+0.997*TBTissue(PRODIGY) and TBBMC(DPXL)= 89.7+0.949*TBBMC(PRODIGY).

CONCLUSIONS

Small differences between the two absorptiometers for both BMD and body composition can be made compatible by use of cross-calibration equations and factors. The discrepancy in body composition compartments requires further research.

Increasing the oxidative stress response allows Escherichia coli to overcome inhibitory effects of condensed tannins

Tannins are plant-derived polyphenols with antimicrobial effects. The mechanism of tannin toxicity towards Escherichia coli was determined by using an extract from Acacia mearnsii (Black wattle) as a source of condensed tannins (proanthocyanidins). E. coli growth was inhibited by tannins only when tannins were exposed to oxygen. Tannins auto-oxidize, and substantial hydrogen peroxide was generated when they were added to aerobic media. The addition of exogenous catalase permitted growth in tannin medium. E. coli mutants that lacked HPI, the major catalase, were especially sensitive to tannins, while oxyR mutants that constitutively overexpress antioxidant enzymes were resistant. A tannin-resistant mutant was isolated in which a promoter-region point mutation increased the level of HPI by 10-fold. Our results indicate that wattle condensed tannins are toxic to E. coli in aerobic medium primarily because they generate H(2)O(2). The oxidative stress response helps E. coli strains to overcome their inhibitory effect.

Gravitational influences upon the maintenance requirements of rabbits

The gravitational component of the feed requirement for the maintenance of body mass has been reported previously for chickens. Similar measurements are reported here for chronically accelerated Polish rabbits, which have mature body masses around 2 kg, approximately the same as for the single-comb white Leghorn chickens used in the earlier experiments. The gravitational influences upon the maintenance requirement and upon body composition were found to be essentially similar for rabbits and chickens, indicating a general phenomenon for small homoiotherms. The principal response in both groups is a greater feed maintenance requirement which increases linearly with the applied acceleration field. The nature of this response is similar to that which follows lesioning of the lateral hypothalamus in rats, though no causal connection between the two phenomena is necessarily implied by these present studies. In monkeys a qualitatively different response of increased body fat is observed.

Metabolic responses of monkeys to increased gravitational fields

A depletion of body fat has been reported by several investigators for various species of homoiotherms exposed to chronic acceleration. Generally the effect is proportional to field strength, and over the size range examined (0.25-5 kg) it becomes more severe in larger animals. There is some evidence that this may be the result of increased secretion of a pituitary hormone, the fat mobilizing substance (FMS). An exception to the defatting effect of chronic acceleration was observed in mature pig-tailed monkeys (Macaca nemestrina)--although they exhibited other changes generally found in homoiotherms exposed to hyperdynamic environments. It is considered that this unusual primate response to chronic acceleration may result from a different geometry of the central nervous system, and its effect upon gravity load distribution in the lower part of the brain.

Effects of chronic acceleration in animals

Chronic acceleration describes the exposure of animals to increased acceleration fields of sufficient intensity and duration to induce physiological adaptation. By comparing the degree of changes observed in several fields with the acceleration intensity, it is possible to derive an estimate of the biological effect of gravity. For technical reasons, such studies are limited to artificial fields produced by protracted centrifugation. Observations by various investigators indicate a fairly general response to chronic acceleration. Over the size range presented by these species (0.04-5 kg), there appears to be a direct relationship between body mass and the degree of the acceleration-induced effect (tolerable field intensity, growth repression, inhibition of fat (correction of far) deposition, etc.). However, different response patterns may obtain in homeotherms that differ significantly from this body size range.

Physiological changes associated with long-term increases in acceleration

The long-term retention of organisms in increased acceleration fields is an experimental approach towards understanding the biological consequences of earth gravity. Such treatment, called chronic acceleration, simulates a change in gravity and requires exposed organisms to adapt physiologically to the new environment. Information from chronic acceleration supplements that from space physiology in understanding gravitational physiology. Many of the responses in long-term exposure to increased acceleration are those which would be anticipated from the imposed symmetrical loading. For example, increased requirements for posture and locomotion induce appropriate changes in musculo-skeletal organs. Displacement of body fluids and increased hydrostatic pressures lead to greater blood volumes and increased tissue hydration. However, there are also specific acceleration effects which cannot be so directly interpreted. Among these are decreases of mature body size and of depot fat, which are proportional in degree to field strength. The role of chronic acceleration research in the development of gravitational biology and its relationship to earth-orbital experiments are considered. The applicability of chronic acceleration studies with human subjects towards planning of deep space exploration is also discussed.

The roles of body mass and gravity in determining the energy requirements of homoiotherms

Studies by Kleiber and by Brody in the 1930's established the 3/4 power of body weight as the unit for comparison of metabolic phenomena in homoiotherms. Later Kleiber conceived of the energy requirement as a composite function, with a thermoregulatory component, proportional to heat loss, and an antigravity component that is directly proportional to body weight. Maintenance feed requirements have been measured with groups of small animals chronically exposed to several acceleration fields. Analysis of the results leads to an arithmetic relationship between the maintenance requirement and acceleration field strength: Fg = Fo+k g Where: F is the maintenance feed requirement (Fg in field of g strength, and Fo where g=0); and, g is the ambient acceleration field strength. When the equations are compared for groups of different body size, Fo tends to vary between the 0.4 and 0.5 power of body mass--and k tends to be the same, irrespective of body mass (BM). These findings tend to confirm the Kleiber concept of a composite nature of homoiotherm maintenance requirements.

Influence of the ambient acceleration field upon acute acceleration tolerance in chickens

It has been demonstrated both in the Russian and in the American space programs that there is a progressive deconditioning of the circulatory system with exposure to weightlessness. Astronauts and cosmonauts returned to Earth have a significantly reduced orthostatic tolerance which will persist for a few days. We have measured the acceleration tolerance of domestic fowl, acutely exposed to a 6 g+z field, as the time over which a normal heart rate can be maintained. This period of circulatory accommodation ends abruptly with a marked bradycardia, which with continued treatment is terminal. For animals which have been previously chronically accelerated (e.g., physiologically adapted to a 2.5 g field) the acute acceleration tolerance is greatly increased. It appears that the influence of the ambient acceleration field in conditioning the responsiveness of the circulatory system is a general phenomenon.