Salmonella enterica: survival, colonization, and virulence differences among serovars.

Data indicate that prevalence of specific serovars of Salmonella enterica in human foodborne illness is not correlated with their prevalence in feed. Given that feed is a suboptimal environment for S. enterica, it appears that survival in poultry feed may be an independent factor unrelated to virulence of specific serovars of Salmonella. Additionally, S. enterica serovars appear to have different host specificity and the ability to cause disease in those hosts is also serovar dependent. These differences among the serovars may be related to gene presence or absence and expression levels of those genes. With a better understanding of serovar specificity, mitigation methods can be implemented to control Salmonella at preharvest and postharvest levels.

Zoonotic bacterial pathogens and mixed crop-livestock farming.

Use of mixed crop-livestock farms (MCLFs) is one of the oldest and most traditional farming methods practiced all over the world, and MCLFs are still one of the major systems of food production, particularly for organic foods. On these typically small farms, livestock are reared primarily on grass and naturally grown crops, while composted animal wastes are used to fertilize the soil for growing crops. Specific to organic MCLFs, biosecurity challenges arise from the fact that animals are reared outdoors, which increases potential for contact with disease vectors including wild birds, rodents, and insects. Organic regulations do not allow the use of chemicals and antibiotics; therefore, alternative methods for control of disease and zoonotic pathogens must be used. Due to the biosecurity challenges and the complexity of the MCLF environment, methods for control of zoonotic pathogens need to be carefully considered in order to be effective and to abide by organic regulations if required. The objectives of this study are to define the complex routes of transmission, as well as the prevalence of potential zoonotic and possible interruption strategies of these pathogens among the food animals and crops produced on MCLFs.

Evaluation of whole-genome sequencing as a genotyping tool for Campylobacter jejuni in comparison with pulsed-field gel electrophoresis and flaA typing.

Campylobacter jejuni is a leading cause of foodborne illness, with poultry and poultry products being leading sources of infection. Epidemiological efforts to trace Campylobacter can be challenging because of the extreme genetic diversity of this bacterium relative to other foodborne pathogens. To enhance tracking and epidemiological efforts, whole-genome sequencing has been used for other foodborne pathogens but not yet been evaluated for practicality with Campylobacter. Thus, the purpose of this study was to evaluate whole-genome sequencing as a genotyping method for C. jejuni by comparing it with 2 commonly used genotyping methods, namely pulsed-field gel electrophoresis (PFGE) and flaA typing. Whole-genome sequence data were generated using the Roche-454 sequencing platform to map Campylobacter strains (VOL_3, VOL_5, VOL_8, VOL_11, and VOL_20) isolated from conventional and organic poultry. Five additional isolates with published genomes were also compared. The PFGE profiles were created using Sma I digestion. For the flaA short variable region sequencing, standard PCR methods were used and high-quality Sanger reads were generated. The PFGE profiles of strains VOL_3 and VOL_11 were found to be indistinguishable, and strain VOL_20 was found indistinguishable from NCTC 11168. Whole-genome comparisons between strains VOL_20 and 11168 were in agreement with the obtained PFGE profiles, as these 2 isolates had very similar genome sizes, a number of shared genes (1,580), and very similar % G-C content (30.6). Of the 8 strains, 2 strains (VOL_3 and VOL_11) had identical flaA types. Whole-genome sequencing was the most discriminatory of the typing methods. However, the cost and time effort needed to sequence and assemble the genomes may hinder efforts, and therefore, we conclude that more bioinformatics tools need to be developed for whole-genome sequencing to be used as an epidemiological tool.

Next-generation sequencing: the future of molecular genetics in poultry production and food safety.

The era of molecular biology and automation of the Sanger chain-terminator sequencing method has led to discovery and advances in diagnostics and biotechnology. The Sanger methodology dominated research for over 2 decades, leading to significant accomplishments and technological improvements in DNA sequencing. Next-generation high-throughput sequencing (HT-NGS) technologies were developed subsequently to overcome the limitations of this first generation technology that include higher speed, less labor, and lowered cost. Various platforms developed include sequencing-by-synthesis 454 Life Sciences, Illumina (Solexa) sequencing, SOLiD sequencing (among others), and the Ion Torrent semiconductor sequencing technologies that use different detection principles. As technology advances, progress made toward third generation sequencing technologies are being reported, which include Nanopore Sequencing and real-time monitoring of PCR activity through fluorescent resonant energy transfer. The advantages of these technologies include scalability, simplicity, with increasing DNA polymerase performance and yields, being less error prone, and even more economically feasible with the eventual goal of obtaining real-time results. These technologies can be directly applied to improve poultry production and enhance food safety. For example, sequence-based (determination of the gut microbial community, genes for metabolic pathways, or presence of plasmids) and function-based (screening for function such as antibiotic resistance, or vitamin production) metagenomic analysis can be carried out. Gut microbialflora/communities of poultry can be sequenced to determine the changes that affect health and disease along with efficacy of methods to control pathogenic growth. Thus, the purpose of this review is to provide an overview of the principles of these current technologies and their potential application to improve poultry production and food safety as well as public health.

Modifying the gastrointestinal ecology in alternatively raised poultry and the potential for molecular and metabolomic assessment.

Consumer demand for nonconventional poultry products continues to increase in the United States. In pasture flock and organic poultry production, probiotics and prebiotic feed additives have potential advantages because they are thought to promote intestinal health and may offer a replacement for current intervention strategies that are not considered acceptable for these production systems. Prebiotics have been demonstrated to produce effects on the gastrointestinal tract including modulation of microflora by promoting selective increases in beneficial bacteria concomitant with decreases in undesirable bacteria. In-depth assessment of microbial community changes during host growth and development as well as the establishment of beneficial microbial species by adding biologicals such as probiotics and prebiotics is important to achieve predictable and consistent improvements in chicken health and productivity. To analyze microflora shifts and metabolites produced by bacteria in the gut as well as host responses to biological additives, sophisticated molecular techniques are now available and are becoming more widely used. Polymerase chain reaction assays, denaturing gradient gel electrophoresis, and temperature gradient gel electrophoresis offer approaches for detecting microbial shifts in the gut. Likewise, the employment of microarrays and molecular analysis of gut tissues can reveal insight into gut physiological and responses to dietary and other changes. Recent application of 16S rDNA sequencing and analysis utilizing basic local alignment search tool (BLAST) and FASTA databases on poultry gut samples have the potential to provide a much more in-depth assessment of the gut microbiome. Utilizing ultra pressure liquid chromatography-mass spectroscopy profiling, metabolomic assessment of gut contents will also allow for parallel comparisons of changes in the gut contents with microbiome and physiological responses. Combining all these technologies will provide a plenary understanding of poultry gut health in alternative production systems.

Optimized culturing and nucleic acid-based methods for the detection of Salmonella enterica in poultry environments.

The main objective of this trial was to set up a series of assays following quantified inoculation of Salmonella samples in 2 initial enrichment methods to ultimately determine the most effective and fastest detection method for recovery of Salmonella in a poultry environment matrix. Samples were randomly split into 2 different containers containing either buffered peptone water (BPW) + yeast extract, or tetrathionate broth (TT) with added iodine and Brilliant Green solution 0.1%. A frozen stock Salmonella culture was thawed and serially diluted 10-fold to inoculate 100 µL of the dilution into the enriched samples. The samples were incubated at 42 and 37°C, respectively, for 24 h and secondarily enriched in modified semi-solid Rappaport Vassiliadis (MSRV) incubated at 42°C. All samples then were reincubated under the same conditions. After secondary enrichment, the samples were streaked onto Chromogenic agar/ XLT4 bi-plates and incubated under the same conditions. After initial inoculation and each 24-h incubation, a portion of the enriched samples was analyzed using a real-time PCR assay. The results of this trial indicate that recovery of Salmonella in a culture-based assay may be enhanced by up to 3 logs by using the TT as the initial enrichment media compared with BPW. The incorporation of MSRV as a secondary cultural selective media after the TT gave the best recovery of Salmonella. These data indicate that considerable time can be saved by using TT as an initial media for Salmonella recovery.

Listeria monocytogenes and hemolytic Listeria innocua in poultry.

Listeria monocytogenes is a ubiquitous, saprophytic, Gram-positive bacterium and occasional food-borne pathogen, often associated with ready-to-eat meat products. Because of the increased consumer interest in organic, all natural, and free range poultry products, it is important to understand L. monocytogenes in the context of such systems. Pasture-reared poultry were surveyed over the course of two 8-wk rearing periods. Cecal, soil, and grass samples were collected for Listeria isolation and characterization. Seven of 399 cecal samples (or 1.75%) were Listeria-positive. All positive cecal samples were obtained from broilers sampled at 2 wk of age. Grass and soil samples were collected from the pasture both before and after introduction of the poultry. Environmental samples collected after introduction of poultry were significantly more likely to contain Listeria (P < 0.001). The results of analytical profile index Listeria, sigB allelic typing, and hlyA PCR tests found that both L. monocytogenes and L. innocua, including hemolytic L. innocua, were recovered from the cecal and environmental (grass/soil) samples. The sigB allelic typing also revealed that (1) positive samples could be composed of 2 or more allelic types; (2) allelic types found in cecal samples could also be found in the environment; and (3) allelic types could persist through the 2 rearing periods. Our data indicate that both pasture-reared poultry and their environment can be contaminated with L. monocytogenes and hemolytic L. innocua.

Assessment of production performance in 2 breeds of broilers fed prebiotics as feed additives.

Pasture-flock-raised poultry are becoming an increasingly popular product, but only limited options are currently available for maintaining gut health. For these producers, prebiotics are an attractive option because they are generally recognized as safe (GRAS) and can be mixed into the feed and thus do not require adjustments to production protocols. However, if prebiotic treatments reduce production performance, they would not be useful to producers. Thus, the objective of this study was to measure performance of pasture-raised broilers fed 1 of 3 prebiotic treatments. For these trials, 2 breeds of birds were used: Naked Neck slow-growing breeds and Cornish White Rock cross fast-growing breeds. The experimental design was replicated for each breed. A total of 340 birds were split into 4 groups, each group fed one feed additive: 1) galactoligosaccharides (2% wt/wt), 2) fructooligosaccharides (1% wt/wt), 3) plum fibers (1% wt/wt), or 4) no additives. During the 8-wk rearing period, 10 birds from each group were collected and euthanized to take small intestine samples. Histological preparations were made from the small intestine tissue, and 4 measurements of villi height and crypt depth from each cross section were taken. Throughout the study, mortality was monitored and BW measurements were taken at 2-wk intervals. For the Cornish White Rock cross, the group receiving the feed supplemented with fructooligosaccharides had higher (P < 0.05) 8-wk BW than those fed Plum; control and birds fed galactoligosaccharides were intermediate. For the Naked Neck breed, the group receiving the plum fibers had the highest final BW. It appears that all 3 feed supplements offered some protective effect for alterations in villi length and crypt depth due to feed withdrawal, but only for the Naked Neck breed. The data indicate the 3 prebiotics utilized in this study could be used without risk of decreasing production performance, but only for Naked Neck breeds.

Detection of Salmonella spp. survival and virulence in poultry feed by targeting the hilA gene.

AIMS: The objectives of this work were to evaluate immunomagnetic beads and a reverse transcriptase (RT)-PCR method for the detection of Salmonella inoculated into feed. In addition, a reverse transcriptase (RT)-PCR method was evaluated for quantifying virulence gene hilA expression of Salmonella ssp. in poultry feed matrices and utilized to determine the influence of poultry feed environmental factors on Salmonella hilA expression. METHODS AND RESULTS: An immunomagnetic separation technique was evaluated for increased recovery of Salmonella from feed. Salmonella cultures were inoculated into feed samples and exposed to heat treatments of 70°C and sampled periodically. From these samples, RNA was collected and hilA gene expression was measured relative to the housekeeping 16S rRNA gene. The immunomagnetic bead protocol increased recovery by 1 log. The up-regulation of hilA was demonstrated after 5 and 10 min of inoculated feed samples being exposed to heat treatment. CONCLUSIONS: From this work, the data indicate that the ability to detect live Salmonella cells in feed samples may be increased by targeting the hilA gene. SIGNIFICANCE AND IMPACT OF THE STUDY: Foodborne salmonellosis originating from poultry is a major problem, and feed is a leading source of contamination in poultry, but detection in feed is complicated by low concentrations. The assays and experiments in this study examine possible improvements to recovery and detection of Salmonella in feed.

In vitro invasion of laying hen ovarian follicles by Salmonella Enteritidis strains.

Salmonella is the major foodborne bacterial pathogen worldwide. Among numerous serotypes, Salmonella Enteritidis (SE) is one of the most common Salmonella serotypes responsible for human infections in the United States. The main source of SE outbreaks is foods associated with raw or undercooked chicken eggs. Salmonella Enteritidis is the only serotype that routinely contaminates eggs. The transovarian transmission of SE and subsequent contamination of the eggs before egg shell formation is considered to be the main route of egg contamination by SE. To evaluate whether invasion of ovarian follicles is an important step during the production of eggs contaminated by SE, we used an in vitro invasion assay to determine ovarian follicle invasion by 5 SE strains. After inoculating the freshly collected ovarian follicles, all 5 SE strains were able to invade into the follicles after 2 h of incubation at 37°C. The mean percentage of SE invasion ranged from 0.016 to 0.034% and no significant difference was found among the SE strains. For Escherichia coli K-12 strain, which was used as a negative control, the mean percentage of invasion was 0.0003%. The in vitro follicle invasion by SE strains demonstrated in this study may reflect the ability of the strains to invade ovarian follicles in laying hens once SE cells reach ovaries through various routes.

Salmonella enterica isolates from pasture-raised poultry exhibit antimicrobial resistance and class I integrons.

AIMS: While considerable foodborne pathogen research has been conducted on conventionally produced broilers and turkeys, few studies have focused on free-range (organic) or pastured poultry. The current surveillance study was designed to isolate, identify and genetically characterize Salmonella from pastured poultry farm environment and from retail samples. METHODS AND RESULTS: In this study, 59 isolates were collected from two pastured poultry farms (n = 164; pens, feed, water and insect traps) and retail carcasses (n = 36) from a local natural foods store and a local processing plant. All isolates were serotyped and analysed phenotypically (antimicrobial resistance profiles) and genotypically (DNA fingerprints, plasmid profiles and integron analysis). Salmonella enterica was detected using standard microbiological methods. Salmonella Kentucky was the most prevalent serotype detected from the sampled sources (53%), followed by Salmonella Enteritidis (24%), Bareilly (10%), Mbandaka (7%), Montevideo (5%) or Newport (2%). All isolates were resistant to sulfisoxazole and novobiocin, and the majority (40/59) possessed class I integrons shown by PCR detection. Each Salmonella serotype elicited a distinct pulsed-field gel electrophoresis fingerprint profile, and unique differences were observed among the serotypes. CONCLUSIONS: The findings of this study show that Salmonella serotypes isolated from pasture-raised poultry exhibit antimicrobial resistance and class I integrons. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that despite the cessation of antibiotic usage in poultry production, antibiotic resistant Salmonella may still be recovered from the environment and poultry products.

Campylobacter biofilm phenotype exhibits reduced colonization potential in young chickens and altered in vitro virulence.

In this study, we evaluated the ability of different Campylobacter phenotypes (biofilm versus planktonic) to colonize young poultry. It has been suggested that a persistent Campylobacter biofilm reservoir may be involved in the initial contamination of poultry flocks. Campylobacter jejuni cultured adherent to agar was utilized as the biofilm model and C. jejuni cultured in broth was evaluated as the planktonic model. In 2 independent trials, 1-d-old broiler chicks were given 1 of 3 treatments: 1) 10(5) cfu.mL(-1) of C. jejuni cultured in broth, 2) 10(5) cfu.mL(-1) of C. jejuni cultured adherent to agar, or 3) no C. jejuni (negative control). Cecal contents of all birds were evaluated by culturing 12 d after the initial challenge with C. jejuni. In both trials, birds challenged with C. jejuni cultured in broth had approximately 3 to 4 log higher cecal Campylobacter concentration than birds challenged with C. jejuni cultured adherent to agar. Using 2 cell lines (INT 407 and DF1), virulence of C. jejuni cultured in broth versus adherent to agar also was evaluated by challenging monolayers of eukaryotic cells with 1 of 3 treatments: 1) 10(5) cfu.mL(-1) of C. jejuni cultured in broth, 2) 10(5) cfu.mL(-1) of C. jejuni cultured adherent to agar, or 3) no C. jejuni (negative control). The virulence study also showed differences of C. jejuni cultured in broth or agar in attachment and invasion abilities to tissue culture cells, but differences were not as consistent as with the chick colonization study. This study indicates that phenotype may play a role in colonization of chickens and virulence by C. jejuni.

Campylobacter jejuni as a secondary colonizer of poultry biofilms.

AIMS: The objective of this study was to determine if survival of culturable Campylobacter jejuni outside the host was increased by entrapment in pre-established biofilms. METHODS AND RESULTS: Campylobacter jejuni was inoculated into four biofilm populations isolated from poultry environments and cultured at three temperatures. Survival of culturable Camp. jejuni in some pre-established biofilms was extended vs survival of culturable Camp. jejuni in broth. But some biofilms were detrimental to survival of culturable Camp. jejuni. Denaturing gradient gel electrophoresis analysis indicated differences in bacterial profiles depending on initial source and temperature of culturing, which may have had impacts on survival of culturable Camp. jejuni. Further investigation showed no evidence of interspecies cell signalling indicating that secondary colonization was only physical. CONCLUSIONS: The results of this study show Camp. jejuni's attachment to surfaces is facilitated by pre-established biofilms and survival of culturable Camp. jejuni may be extended in some pre-established biofilms, but these biofilms do not fully explain long-term survival of culturable Camp. jejuni outside hosts. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides new information concerning survival of culturable Camp. jejuni outside the host and shows biofilms may be important in transmission and prevalence of Camp. jejuni.

Emergency department measurement of urinary S100B in children following head injury: can extracranial injury confound findings?

OBJECTIVE: To assess the potential role of urinary S100B as a prognostic biochemical marker following head injury in children in a UK emergency department setting. METHODS: A case-control pilot study was performed in 20 patients with head injury and 15 controls (with extracranial trauma) aged <13 years and within 12 h of their injury recruited over a 4-month period. Urinary S100B levels were measured at presentation to the emergency department. RESULTS: The two groups showed no significant differences in basic characteristics (height, weight, time to sample collection). 50% of the case group had measurable concentrations of S100B following head injury (range 0.02-0.07 microg/l). All patients in the control group had measurable S100B concentrations following extracranial trauma (range 0.02-0.09 microg/l). No significant rise in S100B concentrations occurred in two patients with severe head injuries (Glasgow Coma Score (GCS) <9) and in one patient with a moderate head injury (GCS 10), despite significant injuries on the CT scan. CONCLUSION: Despite detecting measurable S100B levels in urine following head injury, the same levels are measured following extracranial trauma. Urinary S100B is therefore not useful as an early biochemical marker following head injury in children.

Pasture flock chicken cecal microbiome responses to prebiotics and plum fiber feed amendments.

When prebiotics and other fermentation substrates are delivered to animals as feed supplements, the typical goal is to improve weight gain and feed conversion. In this work, we examined pasture flock chicken cecal contents using next generation sequencing (NGS) to identify and understand the composition of the microbiome when prebiotics and fermentation substrates were supplemented. We generated 16S rRNA sequencing data for 120 separate cecal samples from groups of chickens receiving one of 3 prebiotics or fiber feed additives. The data indicated that respective feed additives enrich for specific bacterial community members and modulate the diversity of the microbiome. We applied synthetic learning in microbial ecology (SLiME) analysis to interpret 16S rRNA microbial community data and identify specific bacterial operational taxonomic units (OTU) that are predictive of the particular feed additives used in these experiments. The results suggest that feed can influence microbiome composition in a predictable way, and thus diet may have indirect effects on weight gain and feed conversion through the microbiome.

On the Function of Mitochondrial Metabolism during Photosynthesis in Spinach (Spinacia oleracea L.) Leaves (Partitioning between Respiration and Export of Redox Equivalents and Precursors for Nitrate Assimilation Products).

The functioning of isolated spinach (Spinacia oleracea L.) leaf mitochondria has been studied in the presence of metabolite concentrations similar to those that occur in the cytosol in vivo. From measurements of the concentration dependence of the oxidation of the main substrates, glycine and malate, we have concluded that the state 3 oxidation rate of these substrates in vivo is less than half of the maximal rates due to substrate limitation. Analogously, we conclude that under steady-state conditions of photosynthesis, the oxidation of cytosolic NADH by the mitochondria does not contribute to mitochondrial respiration. Measurements of mitochondrial respiration with glycine and malate as substrates and in the presence of a defined malate:oxaloacetate ratio indicated that about 25% of the NADH formed in vivo during the oxidation of these metabolites inside the mitochondria is oxidized by a malate-oxaloacetate shuttle to serve extramitochondrial processes, e.g. reduction of nitrate in the cytosol or of hydroxypyruvate in the peroxisomes. The analysis of the products of the oxidation of malate indicates that in the steady state of photosynthesis the activity of the tricarboxylic acid cycle is very low. Therefore, we have concluded that the mitochondrial oxidation of malate in illuminated leaves produces mainly citrate, which is converted via cytosolic aconitase and NADP-isocitrate dehydrogenase to yield 2-oxoglutarate as the precursor for the formation of glutamate and glutamine, which are the main products of photosynthetic nitrate assimilation.

Oxaloacetate transport into plant mitochondria

The properties of oxaloacetate (OA) transport into mitochondria from potato (Solanum tuberosum) tuber and pea (Pisum sativum) leaves were studied by measuring the uptake of 14C-labeled OA into liposomes with incorporated mitochondrial membrane proteins preloaded with various dicarboxylates or citrate. OA was found to be transported in an obligatory counterexchange with malate, 2-oxoglutarate, succinate, citrate, or aspartate. Phtalonate inhibited all of these countertransports. OA-malate countertransport was inhibited by 4, 4'-dithiocyanostilbene-2,2'-disulfonate and pyridoxal phosphate, and also by p-chloromercuribenzene sulfonate and mersalyl, indicating that a lysine and a cysteine residue of the translocator protein are involved in the transport. From these and other inhibition studies, we concluded that plant mitochondria contain an OA translocator that differs from all other known mitochondrial translocators. Major functions of this translocator are the export of reducing equivalents from the mitochondria via the malate-OA shuttle and the export of citrate via the citrate-OA shuttle. In the cytosol, citrate can then be converted either into 2-oxoglutarate for use as a carbon skeleton for nitrate assimilation or into acetyl-coenzyme A for use as a precursor for fatty acid elongation or isoprenoid biosynthesis.

The oral glucose tolerance test (OGTT): effect of rate of ingestion of carbohydrate and different carbohydrate preparations.

The glucose load of the oral glucose tolerance test (OGTT) is well standardized. However, recommendations on rate of ingestion and nature of the load are vague. In this study the effect on blood glucose, serum insulin, C-peptide, and plasma gastric inhibitory polypeptide (GIP) of giving 75 g glucose in 300 ml over 1 and 10 min (G1 and G10) was investigated in six subjects. In five an isocaloric amount of partially hydrolyzed starch (Hycal) was also used (H1 and H10). The fast glucose intake, compared with the slow ingestion, resulted in an earlier rise in blood glucose levels, accompanied by a faster serum insulin and C-peptide response. Between 90 and 135 min blood glucose concentrations were significantly higher after the 10-min glucose intake. At 120 min blood glucose levels were 5.5 +/- 0.5 and 4.7 +/- 0.5 mmol/L, respectively, for G10 and G1 (P less than 0.05). In the first half hour after slow and fast Hycal intake no differences were seen in blood glucose, serum insulin, and C-peptide levels. Between 45 and 120 min blood glucose levels were significantly higher after the 10-min Hycal intake. At 120 min blood glucose levels were 5.3 +/- 0.2 and 4.4 +/- 0.1 mmol/L, respectively, for H10 and H1 (P less than 0.01). Except for a faster rise in glucose and insulin levels after glucose loading in 1 min, no further differences were found, when compared with Hycal. No significant differences were seen in the GIP responses. Thus differences in rates of ingestion can cause significant differences in later results. A standard time for glucose ingestion should be specified.

Comparison of the activity and pharmacokinetics of porcine insulin and human insulin (Novo) as assessed by the glucose clamp technique in normal and diabetic man.

Using the glucose clamp technique, human insulin (Novo) and natural porcine insulin were found to have identical potency in terms of glucose delivery in the second hour of i.v. infusion at low (0.02 U/kg/h; 265 +/- 25 versus 232 +/- 35 mg/min, respectively) and high (0.05 U/kg/h; 467 +/- 47 versus 452 +/- 41 mg/min, respectively) doses in normal man. Insulin metabolic clearance rates, serum in vivo half-life, and rate of onset of action were also similar. In insulin-dependent diabetic subjects, whose blood glucose levels were also held constant by feedback glucose infusion, the free insulin profiles after s.c. injection of neutral soluble human insulin and porcine insulin (0.2 U/kg) were identical, and similar to those after conventional and highly purified bovine insulin preparations. Glucose requirement to maintain normoglycemia for the first 5 h after injection was 49.6 +/- 8.2 g for conventional bovine insulin, 50.4 +/- 10.0 g for highly purified bovine, 40.5 +/- 6.9 g for human insulin, and 50.6 +/- 12.4 g for porcine insulin (NS by analysis of variance). No difference in insulin activity was detected when glucose requirement was expressed in terms of the prevailing free insulin concentration. Responses of blood intermediary metabolite levels were indistinguishable between all insulins in both studies.

Detection of quinolones in commercial eggs obtained from farms in the Espaíllat Province in the Dominican Republic.

Previously, we reported the use of quinolones in broiler chickens resulted in residues in retail poultry meat obtained from nine districts in the Santiago Province of the Dominican Republic. Residues in poultry products are a concern due to consumer allergies and the potential to develop antibiotic-resistant bacteria. Given the use of quinolones in poultry production and our previous findings in poultry meat, the objective of this study was to evaluate the presence of quinolone residues in eggs. Samples were collected from 48 different farms located in three of the four municipalities (Moca, Cayetano Germosén, and Jamao) of the Espaíllat Province. Each farm was sampled three times between July and September for a total of 144 samples. Samples were evaluated qualitatively and quantitatively for quinolone residues using the Equinox test. Operation systems (cage or floor), seasonality, and location were considered along with egg-producer sizes that were defined as small scale, <30,000 eggs per day; medium scale, 30,000 to 60,000 eggs per day; or large scale, >60,000 eggs per day. From small-, medium-, and large-scale producers, 69, 50, and 40% of samples were positive for quinolone residues, respectively. A greater number of samples were positive (61%) in floor-laying hen producers compared with those using cages (40%). In the Jamao municipality, 67% of the samples were positive compared with Moca and Cayetano Germosén, where 56 and 25% of samples were positive, respectively. Sampling time had an effect on percent positives: samples collected in July, August, and September were 71, 19, and 63% positive, respectively. Overall, 51% of the samples obtained from eggs produced in the province of Espaíllat were positive for quinolone residues at levels higher than the maximum limits for edible tissue established by the regulatory agencies, including the European Union and U.S. Department of Agriculture. The results obtained from this research confirmed the presence of quinolone residue in eggs, which may present a health risk to some consumers.