Molecular characterization and biofilm formation potential of Bacillus subtilis and Bacillus velezensis in extended shelf-life milk processing line.

This study aims to characterize Bacillus subtilis complex group from raw, pasteurized, and packaged extended shelf-life (ESL) milk samples, to determine their biofilm potential and source-track the microbial contaminants to control their presence during processing. Isolates were characterized using multi-locus sequence typing (MLST) with 7 housekeeping genes. The primers used were designed from the coding regions with the highest number of polymorphic sites. The heat resistance profile indicated that all 12 isolates are psychrotolerant as well as thermophilic, with temperature ranges of 6°C to 55°C (B43, B44, B52, B54, B55, B56, B57), 6°C to 60°C (B46, B47, B48), and 15°C to 60°C (B49, B50). A general linear model 2-way repeated-measure ANOVA of the biofilm-forming potential of the isolates shows a statistically significant difference across the time of incubation (6, 12, 18, and 24 h). All isolates except 2 formed moderate to strong biofilms, with B44 having the most robust biofilm formation (3.14 ± 0.60). Scanning electron and confocal microscopy images reveal the strain specificity of the biofilm structure. The MLST analysis identified all isolates as belonging to either B. subtilis or Bacillus velezensis. All the isolates were novel sequence types (ST) when compared with the PubMLST database (https://pubmlst.org/) but showed relatedness to isolates in the raw milk that was processed. The closest ST are 96 for B. velezensis and 128 for B. subtilis, mostly isolated from soil. This study presents the significance of biofilms of thermophilic B. subtilis and B. velezensis and their possible perpetuation in the dairy processing plant. The information provided is a call for an innovative food contact surface or any other intervention that can minimize or prevent microbial adhesion in the processing plant, to prevent negative effects in ESL milk.

Detection of extended-spectrum beta-lactamase cefotaxime resistance and virulence genes in Escherichia coli by duplex quantitative real-time PCR and melt curve analysis.

Emerging virulent and antibiotic-resistant pathogens present a global public health risk. Routine monitoring of prevalence within the clinical, environmental and food production setting is vital. Quantitative real-time PCR (qPCR) coupled with melting curve analysis can rapidly and accurately characterize pathogens. We evaluated commercial qPCR mixes based on SYBR Green l and EvaGreen for developing an assay for simultaneously detecting antibiotic resistance (extended-spectrum beta-lactamase, ESBL and blaCTX-M ) and virulence (stx1, stx2 and eae) genes in Escherichia coli (n = 12) isolated from irrigation water and irrigated vegetables. SYBR Green and EvaGreen detected two amplicons (stx1 and blaCTX-M ) and (stx2 and eae) in a single reaction. A higher mean melting temperature (Tm ) separation between targeted amplicons and smoother melting curves were observed with the EvaGreen suggesting better performance when targeting multiple amplicons. Through simple stepwise optimization of DNA, cycling, primers, reaction volume and melting curve scanning rate, we adopted a conventional PCR assay for detection of large amplicons (375-1580 bp) for qPCR. This may facilitate development of cost-effective tailor-made assays for rapid and accurate monitoring of emerging foodborne and environmental pathogens in resource constrained regions.

Modelling the survival of Listeria monocytogenes strains in soft lactic cheese following acid and salt stress exposures.

This study evaluated the survival responses of Listeria monocytogenes strains (individually and mixed) in a soft lactic cheese following acid and salt stress exposures. The Weibull and log-linear with tail models were used to predict the survival responses of the pathogen in the cheese stored at 4°C for 15 days. Both models showed a good prediction accuracy for stressed L. monocytogenes cells (Af = 1·00) and higher prediction errors (Af = 1·12-1·14) for nonstressed cells. The inactivation rates (δ (d) and kmax (d-1 )) were significantly lower (P < 0·05) for cells subjected to stress exposure indicating the enhanced tolerance to food stress. However, while enhanced tolerance appeared to be the main effect of stress pre-exposure, in one susceptible strain (69), stress exposure led to higher rates of inactivation. When introduced into the food as mixed strains, one strain out-lived others and remained as the sole survivor. Such strains that perhaps have a predilection for the food environment can provide more cautious estimates of kinetic parameters for predicting L. monocytogenes responses in foods especially if their stress-hardened tolerant cells are used. SIGNIFICANCE AND IMPACT OF THE STUDY: The ability to predict the growth and survival of Listeria monocytogenes in contaminated RTE foods is essential for listeriosis risk assessment. The results of this study provided valuable information on the kinetic parameters of survival of some L. monocytogenes strains found within the South African food environment. In addition to showing differences in the survival responses among strains, the study also showed the importance of the pre-contamination state of the cells in influencing survival kinetics.

Discovery and development of next generation sGC stimulators with diverse multidimensional pharmacology and broad therapeutic potential.

Nitric oxide (NO)-sensitive soluble guanylyl cyclase (sGC), an enzyme that catalyzes the conversion of guanosine-5'-triphosphate (GTP) to cyclic guanosine-3',5'-monophophate (cGMP), transduces many of the physiological effects of the gasotransmitter NO. Upon binding of NO to the prosthetic heme group of sGC, a conformational change occurs, resulting in enzymatic activation and increased production of cGMP. cGMP modulates several downstream cellular and physiological responses, including but not limited to vasodilation. Impairment of this signaling system and altered NO-cGMP homeostasis have been implicated in cardiovascular, pulmonary, renal, gastrointestinal, central nervous system, and hepatic pathologies. sGC stimulators, small molecule drugs that synergistically increase sGC enzyme activity with NO, have shown great potential to treat a variety of diseases via modulation of NO-sGC-cGMP signaling. Here, we give an overview of novel, orally available sGC stimulators that Ironwood Pharmaceuticals is developing. We outline the non-clinical and clinical studies, highlighting pharmacological and pharmacokinetic (PK) profiles, including pharmacodynamic (PD) effects, and efficacy in a variety of disease models.

Quantitative assessment of human exposure to extended spectrum and AmpC ß-lactamases bearing E. coli in lettuce attributable to irrigation water and subsequent horizontal gene transfer.

The contribution of the fresh produce production environment to human exposure with bacteria bearing extended spectrum ß-lactamases and AmpC ß-lactamases (ESBL/AmpC) has not been reported. High prevalence of ESBLs/AmpC bearing E. coli as well as a high gene transfer efficiency of lettuce and irrigation water E. coli isolates was previously reported. This stochastic modeling was aimed at quantitatively assessing human exposure to ESBL/AmpC bearing E. coli through lettuce attributable to irrigation water and subsequent horizontal gene transfer. Modular process risk approach was used for the quantitative exposure assessment and models were constructed in Ms. Excel spreadsheet with farm to consumption chain accounted for by primary production, processing, retail and consumer storage. Probability distributions were utilised to take into account the variability of the exposure estimates. Exposure resulting from ESBL/AmpC positive E. coli and gene transfer was taken into account. Monte Carlo simulation was carried out using @Risk software followed by sensitivity and scenario analysis to assess most effective single or combinations of mitigation strategies for the ESBL/AmpC positive E. coli events from farm to fork. Three percent of South African lettuce consumers are exposed to lettuce contaminated with about 106.4±106.7 (95% CI: 105.1-107) cfu of ESBL/AmpC positive E. coli per serving. The contribution of originally positive isolates and conjugative genetic transfer was 106±106.7 (95% CI: 105-107) and 105.2±105.6 (95% CI: 103.9-105.8) cfu per serving respectively. Proportion of ESBL/AmpC positive E. coli (Spearman's correlation coefficient (ρ)=0.85), conjugative gene transfer (ρ=0.05-0.14), washing in chlorine water (ρ=0.18), further rinsing (ρ=0.15), and prevalence of E. coli in irrigation water (ρ=0.16) had highest influence on consumer exposure. The most effective single methods in reducing consumer exposure were reduction in irrigation water microbial quality variation (87.4% reduction), storage period (49.9-87.4% reduction) and growth rate reduction by 75% (90% reduction). Reduction in growth rate together with storage time (92.1-99.4%) and reduction in storage time combined with E. coli concentration in irrigation water (95-96% reduction) were most effective combinations of mitigation measures. The high variation in exposure reflected the high irrigation water quality variation. The exposure levels may impose higher consumer risk than acceptable for irrigation water risk. E. coli contamination and growth related measures, as well as measures to reduce contamination with antimicrobial resistant E. coli from lettuce production environment are recommended. This exposure model could form a basis for the development of similar models assessing the impact of contaminated irrigation water and gene transfer in other microbial hazards, antimicrobial resistance types and fresh produce types.

Characterization of Escherichia coli and other Enterobacteriaceae in producer-distributor bulk milk.

The current study was undertaken to characterize Escherichia coli and other Enterobacteriaceae in raw and pasteurized producer-distributor bulk milk (PDBM). A total of 258 samples were collected from purchase points in 8 provinces in South Africa. The samples were tested for antibiotic residues, phosphatase, total aerobic bacteria, coliforms, and E. coli counts. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used for identification of isolates. Escherichia coli isolates were characterized for virulence factors, antimicrobial resistance, serotypes, and presumptive E. coli O157:H7. Antibiotic residues and alkaline phosphatase were detected in 2% of both raw and pasteurized PDBM (n=258) and 21% pasteurized PDBM (n=104) samples, respectively. A total of 729 isolates belonging to 21 genera and 59 species were identified. Escherichia coli, Enterobacter cloacae, Klebsiella oxytoca, and Raoultella ornithinolytica were the most abundant species. Spoilage Enterobacteriaceae species exceeded 50% of the total isolates. Escherichia coli was detected and isolated from 36% of the milk samples. Thirty-one E. coli isolates harbored virulence genes stx1/stx2 and 38% (n=121) were presumptive O157:H7. The prevalence of samples with presumptive shigatoxin producing E. coli was 10%. Antimicrobial-resistant E. coli isolates were detected in 70% of the milk samples with 36% of stx1/stx2 positive E. coli showing multi-drug resistance. Information obtained from the study will be used for modeling the public health risk posed by milkborne pathogens in PDBM, which in many cases is consumed by poor and vulnerable members of the population.

Vascular tone pathway polymorphisms in relation to primary open-angle glaucoma.

AIMS: Vascular perfusion may be impaired in primary open-angle glaucoma (POAG); thus, we evaluated a panel of markers in vascular tone-regulating genes in relation to POAG. METHODS: We used Illumina 660W-Quad array genotype data and pooled P-values from 3108 POAG cases and 3430 controls from the combined National Eye Institute Glaucoma Human Genetics Collaboration consortium and Glaucoma Genes and Environment studies. Using information from previous literature and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, we compiled single-nucleotide polymorphisms (SNPs) in 186 vascular tone-regulating genes. We used the 'Pathway Analysis by Randomization Incorporating Structure' analysis software, which performed 1000 permutations to compare the overall pathway and selected genes with comparable randomly generated pathways and genes in their association with POAG. RESULTS: The vascular tone pathway was not associated with POAG overall or POAG subtypes, defined by the type of visual field loss (early paracentral loss (n=224 cases) or only peripheral loss (n=993 cases)) (permuted P≥0.20). In gene-based analyses, eight were associated with POAG overall at permuted P<0.001: PRKAA1, CAV1, ITPR3, EDNRB, GNB2, DNM2, HFE, and MYL9. Notably, six of these eight (the first six listed) code for factors involved in the endothelial nitric oxide synthase activity, and three of these six (CAV1, ITPR3, and EDNRB) were also associated with early paracentral loss at P<0.001, whereas none of the six genes reached P<0.001 for peripheral loss only. DISCUSSION: Although the assembled vascular tone SNP set was not associated with POAG, genes that code for local factors involved in setting vascular tone were associated with POAG.

Heme deficiency of soluble guanylate cyclase induces gastroparesis.

BACKGROUND: Soluble guanylate cyclase (sGC) is the principal target of nitric oxide (NO) to control gastrointestinal motility. The consequence on nitrergic signaling and gut motility of inducing a heme-free status of sGC, as induced by oxidative stress, was investigated. METHODS: sGCß1 (H105F) knock-in (apo-sGC) mice, which express heme-free sGC that has basal activity, but cannot be stimulated by NO, were generated. KEY RESULTS: Diethylenetriamine NONOate did not increase sGC activity in gastrointestinal tissue of apo-sGC mice. Exogenous NO did not induce relaxation in fundic, jejunal and colonic strips, and pyloric rings of apo-sGC mice. The stomach was enlarged in apo-sGC mice with hypertrophy of the muscularis externa of the fundus and pylorus. In addition, gastric emptying and intestinal transit were delayed and whole-gut transit time was increased in the apo-sGC mice, while distal colonic transit time was maintained. The nitrergic relaxant responses to electrical field stimulation at 1-4 Hz were abolished in fundic and jejunal strips from apo-sGC mice, but in pyloric rings and colonic strips, only the response at 1 Hz was abolished, indicating the contribution of other transmitters than NO. CONCLUSIONS & INFERENCES: The results indicate that the gastrointestinal consequences of switching from a native sGC to a heme-free sGC, which cannot be stimulated by NO, are most pronounced at the level of the stomach establishing a pivotal role of the activation of sGC by NO in normal gastric functioning. In addition, delayed intestinal transit was observed, indicating that nitrergic activation of sGC also plays a role in the lower gastrointestinal tract.

Survival of Escherichia coli o157: h7 co-cultured with different levels of Pseudomonas fluorescens and Lactobacillus plantarum on fresh beef

The purpose of this study was to investigate the effect of different levels of Pseudomonas fluorescens (10² and 10(6)log10 cfu/ml)and Lactobacillus plantarum (10² and 10(4)log10 cfu/ml)on the growth of Escherichia coli O157:H7 on beef loins. Beef loins inoculated with E. coli O157:H7 and P. fluorescens were aerobically stored for 7 days at 4 ºC, while those inoculated with E. coli O157:H7 and L. plantarum were vacuum packaged and stored for 8 weeks at 4 ºC. Aerobic Plate Counts (APC), E. coli O157:H7 and either P. fluorescens or L. plantarum counts were determined at different storage intervals. For the aerobically packaged beef loins, E. coli O157:H7 was detected throughout the 7 day storage period regardless of the P. fluorescens level in the inoculum. For the vacuum packaged beef loins, similar inoculum levels of E. coli O157:H7 and L. plantarum allowed E. coli O157:H7 to survive until week 5 of storage, while a higher inoculum level of L. plantarum inhibited E. coli O157:H7 from week 3. Once fresh beef has been contaminated with E. coli O157:H7, the level of P. fluorescens in the background flora does not inhibit its survival and growth. However, under vacuum storage, the application of L. plantarum as a biopreservative inhibits the survival of E. coli O157:H7 on beef. The higher the level of L. plantarum in the system, the earlier the onset of the inhibition. Farmers and abattoirs have to strengthen preventive strategies to eliminate contamination of beef carcasses with E. coli O157:H7.

Effect of chlorine, blanching, freezing, and microwave heating on Cryptosporidium parvum viability inoculated on green peppers.

Cryptosporidium parvum oocysts have been found on the surface of vegetables in both developed and developing countries. C. parvum can contaminate vegetables via various routes, including irrigation water. This study investigated the effect of individual treatments of chlorine, blanching, blast freezing, and microwave heating, as well as combined treatments of chlorine and freezing, and chlorine and microwave heating on the viability of C. parvum oocysts inoculated on green peppers. The viability of the oocysts after the treatments was assessed using propidium iodide and a flow cytometer. Based on the propidium iodide staining, the chlorine treatments did not affect the viability of the oocysts. Blast freezing significantly inactivated 20% of the oocysts. Microwave heating and blanching significantly inactivated 93% of oocysts. Treatment with chlorine followed by blast freezing did not affect the viability of the oocysts significantly. Treatment with chlorine and microwave heating was significantly more effective than microwave heating alone and inactivated 98% of the oocysts. The study indicates that C. parvum oocysts are sensitive to heat and, to some extent, to blast freezing, but are resistant to chlorine. Therefore, the use of chlorine during vegetable processing is not a critical control point for C. parvum oocysts, and the consumption of raw or minimally processed vegetables may constitute a health risk as C. parvum oocysts can still be found viable on ready-to-eat, minimally processed vegetables.

Survival of Escherichia coli o157:h7 co-cultured with different levels of pseudomonas fluorescens and lactobacillus plantarum on fresh beef.

The purpose of this study was to investigate the effect of different levels of Pseudomonas fluorescens (10(2) and 10(6) log10 cfu/ml) and Lactobacillus plantarum (10(2) and 10(4) log10 cfu/ml) on the growth of Escherichia coli O157:H7 on beef loins. Beef loins inoculated with E. coli O157:H7 and P. fluorescens were aerobically stored for 7 days at 4 ºC, while those inoculated with E. coli O157:H7 and L. plantarum were vacuum packaged and stored for 8 weeks at 4 ºC. Aerobic Plate Counts (APC), E. coli O157:H7 and either P. fluorescens or L. plantarum counts were determined at different storage intervals. For the aerobically packaged beef loins, E. coli O157:H7 was detected throughout the 7 day storage period regardless of the P. fluorescens level in the inoculum. For the vacuum packaged beef loins, similar inoculum levels of E. coli O157:H7 and L. plantarum allowed E. coli O157:H7 to survive until week 5 of storage, while a higher inoculum level of L. plantarum inhibited E. coli O157:H7 from week 3. Once fresh beef has been contaminated with E. coli O157:H7, the level of P. fluorescens in the background flora does not inhibit its survival and growth. However, under vacuum storage, the application of L. plantarum as a biopreservative inhibits the survival of E. coli O157:H7 on beef. The higher the level of L. plantarum in the system, the earlier the onset of the inhibition. Farmers and abattoirs have to strengthen preventive strategies to eliminate contamination of beef carcasses with E. coli O157:H7.

Role of the soluble guanylyl cyclase alpha1-subunit in mice corpus cavernosum smooth muscle relaxation.

Soluble guanylyl cyclase (sGC) is the major effector molecule for nitric oxide (NO) and as such an interesting therapeutic target for the treatment of erectile dysfunction. To assess the functional importance of the sGCalpha(1)beta(1) isoform in corpus cavernosum (CC) relaxation, CC from male sGCalpha(1)(-/-) and wild-type mice were mounted in organ baths for isometric tension recording. The relaxation to endogenous NO (from acetylcholine, bradykinin and electrical field stimulation) was nearly abolished in the sGCalpha(1)(-/-) CC. In the sGCalpha(1)(-/-) mice, the relaxing influence of exogenous NO (from sodium nitroprusside and NO gas), BAY 41-2272 (NO-independent sGC stimulator) and T-1032 (phosphodiesterase type 5 inhibitor) were also significantly decreased. The remaining exogenous NO-induced relaxation seen in the sGCalpha(1)(-/-) mice was significantly decreased by the sGC-inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. The specificity of the impairment of the sGC-related responses was demonstrated by the unaltered relaxations seen with forskolin (adenylyl cyclase activator) and 8-pCPT-cGMP (cGMP analog). In conclusion, the sGCalpha(1)beta(1) isoform is involved in corporal smooth muscle relaxation in response to NO and NO-independent sGC stimulators. The fact that there is still some effect of exogenous NO in the sGCalpha(1)(-/- mice suggests the contribution of (an) additional pathway(s).

The distribution of Staphylococci in bioaerosols from red-meat abattoirs.

The quality and shelf-life of perishable foodstuffs can be reduced by high concentrations in the processing environment of bioaerosols consisting of spoilage microbiota. A lack of documented literature on the distribution of such bioaerosols has, however, led to the underestimation of their impact. In the study reported here, the deboning rooms of selected South African red-meat abattoirs were investigated for airborne concentrations of staphylococci; the authors studied the distribution of Staphylococcus species in general, as well as the coagulase types of Staphylococcus aureus in particular. Average staphylococci bioaerosol concentrations varied considerably among the abattoirs investigated, with Abattoir B having the highest counts (3 x 10(2) CFUs/m3) and Abattoir A having the lowest (7.6 CFUs/m3). There was a significant link between bioaerosols and microbial loads from red meat in the same environment. The recorded levels were, however, well below the recommended maximum limits for bioaerosols suggested by various international and governmental authorities. Staphylococcus xylosus and S. saprophyticus were found to be the most abundant species in the air of the deboning rooms, while among S. aureus coagulase types, Type III and Type VIII were predominant. On the basis of the ecology of the bacterial groups, the authors suggest probable sources of staphylococcal bioaerosols and propose strategies that could be developed for red-meat abattoirs to reduce the levels of airborne pathogens.

Use of gamma-irradiation to reduce high levels of Staphylococcus aureus on casein-whey protein coated moist beef biltong.

Moist beef biltong strips (mean moisture content = 53.6%, NaCl content = 1.91% and a(w) = 0.979) was inoculated with Staphylococcus aureus ATCC 9441 (10(6)-10(7) cfu/g), or sprayed with distilled water (non-inoculated controls). Both non-inoculated and inoculated biltong strips were coated with a casein-whey protein (1:1) edible coating followed by irradiation to a target dose of 4 kGy. S. aureus, aerobic plate, yeast and mould counts were performed to determine the effect of gamma-irradiation and the edible coating on inoculated S. aureus and the spoilage flora of the biltong. Moisture and NaCl content, a(w) and pH measurements were also performed. None of the intrinsic properties were affected to a practically significant extent. Irradiation reduced all microbial counts (P < 0.05), i.e. inoculated S. aureus (6 log cycles), aerobic plate count (5-6 log cycles) and yeast and mould counts (1-2 log cycles). Irradiation at 4 kGy is thus effective to ensure safety of moist beef biltong, and provided that initial fungal counts are not excessive, may extend the shelf-life. The edible coating had no significant effect (P > 0.05) on microbial counts, possibly because the high moisture content of the biltong diminished its oxygen barrier properties.

Effect of γ-irradiation on the sensory quality of moist beef biltong.

Moist beef biltong (mean moisture content=46.7% and a(w)=0.919) was vacuum packaged and irradiated to target doses of 0, 2, 4, 6, and 8kGy. Thiobarbituric acid reactive substance (TBARS) measurements and sensory difference and hedonic tests were performed to determine the effect of γ-irradiation on the sensory quality of the biltong. TBARS values only increased significantly (P<0.05) if biltong was irradiated to at least 8kGy, indicating a low degree of lipid oxidation. This can be attributed to the low fat content (on average 1.53%) of the biltong used in this study, as well as irradiation under vacuum conditions. All irradiated samples could be discriminated (P<0.05) from non-irradiated biltong, but none was rated as less acceptable. Dissipation of volatiles before tasting (by exposing the product to aerobic conditions before consumption), a low degree of lipid oxidation and liking of distinct 'irradiation flavours' possibly all attributed to the flavour of irradiated biltong not being regarded as unacceptable compared to controls. Biltong irradiated at 2 and 4kGy was however liked significantly more (P<0.05) than other samples, indicating that slight, non-oxidative irradiation-induced flavour changes may contribute to flavour development in the usually more bland moist beef biltong. Although lean moist beef biltong can thus be irradiated to doses up to 8kGy without adversely affecting the sensory acceptability, low dose irradiation (⩽4kGy) is most feasible to optimise the sensory quality.

Bacterial populations associated with meat from the deboning room of a high throughput red meat abattoir.

Developing countries are faced with high incidences of food poisoning outbreaks, with obvious economic consequences. In highly perishable foodstuffs such as fresh red meat the threat of food poisoning is particularly intense. In this study, red meat samples were collected from a deboning room of a high throughput abattoir. The samples were analysed for the presence of Bacillus cereus., Staphylococcus aureus., Pseudomonas spp., Listeria monocytogenes., Escherichia coli and Salmonella spp. The aerobic plate counts as well as Enterobacteriaceae were also enumerated. Almost without exception the counts exceeded the microbiological guidelines for raw meat as proposed by the South African Department of Health. The average B. cereus count over the sampling period was 8.32 × 10(3) cfu, g (-1), for S. aureus and Pseudomonas spp. 1.72 × 10(5) and 1.7 × 10(5) cfu g(-1) respectively and for E. coli 3.4 × 10(5) cfu g(-1). Sixty percent of the samples were positive for presumptive Salmonella spp. while 52% of the samples tested positive for the presence of L. monocytogenes. The aerobic plate and Enterobacteriaceae counts were 1.7 × 10(7) and 4.6 × 10(6) cfu g(-1), respectively. The data highlighted the need for a more systematic approach to ensuring safe food through implementing quality control methods to prevent the entry and proliferation of pathogens in meat and meat products, especially during processes with a high degree of handling, such as deboning.

Colour changes and consumer acceptability of bulk packaged pork retail cuts stored under O(2), CO(2) and N(2).

A centralised bulk packaging technique, utilising various gas mixtures, c. 100% CO(2)+oxygen scavenger, c. 80% O(2):20% CO(2) and c. 25% CO(2):50% N(2):25% O(2), was evaluated in terms of consumer acceptability and colour. The inclusion of an oxygen scavenger ensured that pork retail chops bulk packaged in a 100% CO(2) were as acceptable after 0, and 14 days bulk storage and subsequent retail display than chops stored in oxygen-enriched atmospheres. The study also indicated that a saturation level of 10 and higher indicated that the appearance of the pork chop was acceptable to the consumer panel. From the results of this study it is apparent that consumers find pork retail packs, bulk packaged in oxygen depleted atmospheres, as acceptable as pork chops stored in oxygen enriched atmospheres.

Bacterial populations associated with bulk packaged beef supplemented with dietary vitamin E.

Five Simmentaler type calves were fed diets supplemented with 500 mg vitamin E per day and five fed control diets, Rump steaks from each carcass were PVC-overwrapped and bulk packaged in 100% CO2 or 20% CO2:80% O2. Bulk packs were stored up to 42 days at 4 degrees C and PVC-overwrapped samples subsequently displayed up to 7 days at 4 degrees C. After display the Aerobic Plate Count (APC) of steaks was determined and four colonies were randomly selected from the highest dilution APC plates showing growth. A total of 627 colonies were obtained. Gram-reaction, catalase, oxidase, morphology and motility of the isolates were determined. The gram-negative and gram-positive isolates were then identified using a dichotomous identification key. Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp. predominated on rump steaks from both feeding treatments and in packaging treatments. After 42 days bulk storage Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria and Acinetobacter spp. predominated in 20% CO2:80% O2 and 100% CO2 bulk packaging. Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp. predominated on rump steaks, from both feeding and packaging treatments, during the aerobic display period of 7 days.

Successful results of a bipolar active fixation lead for atrial application: an interim analysis.

Adequate atrial lead performance consists of stable sensing and pacing properties. To evaluate whether the CPI 4269 bipolar lead, covered with mannitol (Sweet Tip), in the atrial position encounters these properties, we performed a prospective study of this lead. After complete dissolution of the mannitol helix, mapping of the atrium to obtain the highest electrogram and lowest threshold was followed by screw-in into the endocardium. Intraoperative measurements were performed and long-term follow-up was scheduled every 6 to 12 months to measure threshold and perform an intracardial electrogram. Between February 1993 and December 1996, a total number of 73 leads in the atrial position in a consecutive series of patients was implanted. Implantation was performed in 28 patients receiving an AAIR and 45 patients a DDDR pacemaker. Reason for pacemaker implantation was a third-degree AV block in 37% of patients, type II second-degree AV block in 25%, sick sinus syndrome in 35%, and drug refractory paroxysmal atrial fibrillation following His-bundle ablation in 3%. The intraoperative bipolar atrial electrogram had a mean voltage of 4.25 +/- 2.1 mV. The acute atrial bipolar threshold was 0.63 +/- 0.43 V, and current was 1.35 +/- 0.81 mA at a 1.0-ms pulse duration. The mean acute resistance of the lead was 572 +/- 86 Ohm. After a mean follow-up of 18.3 months, the bipolar intracardial electrogram was 3.37 +/- 2.00 mV, the mean atrial threshold measured at the last outpatient clinic visit was 0.99 +/- 0.74 V and the mean impedance was 640 +/- 127 Ohm. A sensing problem due to traction of the atrial lead occurred in only one patient. Acute and late dislodgement did not occur. The CPI 4269 (Sweet Tip) lead is manufactured with a dissolvable capsule covering the helix tip electrode, permitting a safe passage through the venous system. This interim analysis shows that this lead in the atrial position has favorable acute and chronic results.