Left ventricular geometry, tissue composition, and residual stress in High Fat Diet Dahl-Salt sensitive rats.

BACKGROUND: Hypertension drives myocardial remodeling, leading to changes in structure, composition and mechanical behavior, including residual stress, which are linked to heart disease progression in a gender-specific manner. Emerging therapies are also targeting constituent-specific pathological features. All previous studies, however, have characterized remodeling in the intact tissue, rather than isolated tissue constituents, and did not include sex as a biological variable. OBJECTIVE: In this study we first identified the contribution of collagen fiber network and myocytes to the myocardial residual stress/strain in Dahl-Salt sensitive rats fed with high fat diet. Then, we quantified the effect of hypertension on the remodeling of the left ventricle (LV), as well as the existence of sex-specific remodeling features. METHODS: We performed mechanical tests (opening angle, ring-test) and histological analysis on isolated constituents and intact tissue of the LV. Based on the measurements from the tests, we performed a stress analysis to evaluate the residual stress distribution. Statistical analysis was performed to identify the effects of constituent isolation, elevated blood pressure, and sex of the animal on the output of both experimental measures and modeling results. RESULTS: Hypertension leads to reduced residual stress/strain intact tissue, isolated collagen fibers, and isolated myocytes in male and female rats. Collagen remains the largest contributor to myocardial residual stress in both normotensive and hypertensive animals. We identified sex-differences in both hypertensive and normotensive animals. CONCLUSIONS: We observed both constituent- and sex-specific remodeling features in the LV of an animal model of hypertension.

Dose rates of antimicrobial substances in boar semen preservation-time to establish new protocols.

To achieve a standardized number of spermatozoa in the final AI dose, varying amounts of extender fluid with a fixed concentration of antimicrobial substances are currently added to boar ejaculates. This practice ignores the different degrees of dilution of the antimicrobials in the end product. In calculating the final concentration of gentamicin in AI doses from 27,538 processed boar ejaculates, we demonstrated varying gentamicin concentrations in the resultant extended boar semen samples. The median concentration was 220.37 mg/L. In 25 of the samples (0.09%), the gentamicin concentration fell below 5 mg/L, which is close to or below the epidemiological cut-off value for many bacteria. We calculated the minimum inhibitory concentration of gentamicin for bacteria isolated from raw and extended ejaculates. Five of the isolates from extended ejaculates exceeded the maximum test concentration of 512 mg/L. As a result, we are presenting an alternative method of boar semen preservation whereby a particular combination of gentamicin concentrate and antibiotic-free extender is incorporated that standardizes the antibiotic concentration in the diluted semen. The addition of standardized antibiotic concentrations did not negatively affect sperm quality when compared to the use of ready-to-use extenders. In conclusion, an end volume-based and standardized addition of gentamicin to boar ejaculates can be a helpful alternative to prevent insufficient dosage of antibiotics in liquid preserved boar semen without affecting semen quality.

Challenges and Limits Using Antimicrobial Peptides in Boar Semen Preservation.

Antibiotics are of great importance for the preservation of ejaculates for livestock breading. The use of antibiotics, however, is not an appropriate compensation for a lack of hygiene standards in artificial insemination (AI) centres. Sophisticated hygiene management and the proper identification of hygienic critical control points (HCCPs) at AI centres provide the basis for counteracting the development of antibiotic resistance in contaminant bacteria and their settlement in AI centres. In recent years, efforts have been made to use antimicrobial peptides (AMPs) in the preservation of boar semen. Investigations have included the testing of synthetic magainin derivatives and cyclic hexapeptides. One prerequisite for the application of AMPs is that they have a minor impact on eukaryotic cells. Bacterial selectivity, proteolytic stability, thermodynamic resistance, and mechanisms including synergistic interaction with conventional antibiotics have made cyclic hexapeptides highly promising candidates for potential application as peptide antibiotics for semen preservation.

Analysis of hygienic critical control points in boar semen production.

The present study addresses the microbiological results of a quality control audit in artificial insemination (AI) boar studs in Germany and Austria. The raw and processed semen of 344 boars in 24 AI boar studs were analyzed. Bacteria were found in 26% (88 of 344) of the extended ejaculates and 66.7% (18 of 24) of the boar studs. The bacterial species found in the AI dose were not cultured from the respective raw semen in 95.5% (84 of 88) of the positive samples. These data, together with the fact that in most cases all the samples from one stud were contaminated with identical bacteria (species and resistance profile), indicate contamination during processing. Microbiological investigations of the equipment and the laboratory environment during semen processing in 21 AI boar studs revealed nine hygienic critical control points (HCCP), which were addressed after the first audit. On the basis of the analysis of the contamination rates of the ejaculate samples, improvements in the hygiene status were already present in the second audit (P = 0.0343, F-test). Significant differences were observed for heating cabinets (improvement, P = 0.0388) and manual operating elements (improvement, P = 0.0002). The odds ratio of finding contaminated ejaculates in the first and second audit was 1.68 (with the 95% confidence interval ranging from 1.04 to 2.69). Furthermore, an overall good hygienic status was shown for extenders, the inner face of dilution tank lids, dyes, and ultrapure water treatment plants. Among the nine HCCP considered, the most heavily contaminated samples, as assessed by the median scores throughout all the studs, were found in the sinks and/or drains. High numbers (>10(3) colony-forming units/cm(2)) of bacteria were found in the heating cabinets, ejaculate transfer, manual operating elements, and laboratory surfaces. In conclusion, the present study emphasizes the need for both training of the laboratory staff in monitoring HCCP in routine semen production and audits in such AI centers for the external control of hygiene parameters.

Polar bear encephalitis: establishment of a comprehensive next-generation pathogen analysis pipeline for captive and free-living wildlife.

This report describes three possibly related incidences of encephalitis, two of them lethal, in captive polar bears (Ursus maritimus). Standard diagnostic methods failed to identify pathogens in any of these cases. A comprehensive, three-stage diagnostic 'pipeline' employing both standard serological methods and new DNA microarray and next generation sequencing-based diagnostics was developed, in part as a consequence of this initial failure. This pipeline approach illustrates the strengths, weaknesses and limitations of these tools in determining pathogen caused deaths in non-model organisms such as wildlife species and why the use of a limited number of diagnostic tools may fail to uncover important wildlife pathogens.

Comparative quantification of the in vitro activity of veterinary fluoroquinolones.

The aim of this study was to compare the in vitro antimicrobial activity of the veterinary fluoroquinolones against a panel of recently isolated porcine and bovine bacterial pathogens. The study used enrofloxacin as a benchmark against which other agents were compared, being the most common fluoroquinolone used in treatment of bovine and porcine infections. The activity of ciprofloxacin was also assessed as it is the main metabolite of enrofloxacin in cattle. Enrofloxacin and ciprofloxacin generally showed higher antibacterial activity, in terms of MIC(50) values, for most pathogen species when compared with marbofloxacin, difloxacin, danofloxacin and norfloxacin. Ciprofloxacin showed significantly greater in vitro antibacterial activity than enrofloxacin against M. haemolytica, P. multocida and E. coli, whereas enrofloxacin showed greater activity than ciprofloxacin against S. aureus. Marbofloxacin was significantly more active than enrofloxacin against M. haemolytica, E. coli and B. bronchiseptica but less active against P. multocida, S. aureus, coagulase negative Staphylococci, S. dysgalactiae, S. uberis, A. pleuropneumoniae and S. suis. Danofloxacin was significantly less active than enrofloxacin against P. multocida, E. coli, S. uberis, A. pleuropneumoniae and S. suis. Enrofloxacin and its metabolite ciprofloxacin showed the highest in vitro activities against most bovine pathogens tested and the porcine pathogens also showed a high degree of sensitivity to enrofloxacin. These data facilitate further pharmacokinetic/pharmacodynamic comparison of fluoroquinolones currently used in veterinary medicine.

DNA heterogeneity determined by flow cytometry in prostatic adenocarcinoma--necessitating multiple site analysis.

Although DNA ploidy analysis of prostate cancer is generally associated with grade, stage, clinical outcome, and responsiveness to androgen therapy, one possible reason cited for contrary reports may be tumor heterogeneity. A preliminary report using flow cytometric analysis of punch biopsies demonstrated DNA heterogeneity in five of nine patients. We evaluated 75 patients by cutting whole mounts of formalin fixed prostatectomy tissue every 0.6 cm. All malignant areas and a selected normal area were circumscribed, excised, remounted, and 1-3 50 mu thick sections removed. The nuclei were extracted by a Hedley technique and the DNA stained with propidium iodide. Each whole mount had an average of 1 distinct malignant area (range of 1-6 areas per whole mount block). Nuclei were analyzed on a Becton Dickinson (San Jose, CA) FACScan flow cytometer equipped with RFIT DNA software program. After excluding histograms with CVs > 8.0% and/or "suspicious" diploid histograms having a right "shoulder," 75 or 87 patients still had > or = 2 malignant sites available for analysis (average 4, range 2-9 malignant sites/patient). The 322 histograms had an average CV of 4.4%. Thirty of 75 patients (40%) showed DNA heterogeneity in multiple samples taken from the same prostate. There were 37 prostates with only diploid (D), 1 with only tetraploid (T), 7 with only aneuploid (A), 20 with D plus A, 7 with D plus T, 2 with D plus T plus A, and 1 with a D plus suspected hypodiploid DNA content. Exclusion of the tetraploid and "near diploid aneuploid" cases still resulted in 16% (12/75) of the patients having a diploid versus aneuploid DNA content heterogeneity. Because 40% of the prostates contained a different ploidy depending on which area was sampled, this report suggests multiple sites of malignancy must be analyzed to more accurately assess the ploidy status of prostatic adenocarcinoma.