A free-fall determination of the newtonian constant of gravity

Recent determinations of the Newtonian constant of gravity have produced values that differ by nearly 40 times their individual error estimates (more than 0.5%). In an attempt to help resolve this situation, an experiment that uses the gravity field of a one-half metric ton source mass to perturb the trajectory of a free-falling mass and laser interferometry to track the falling object was performed. This experiment does not suspend the test mass from a support system. It is therefore free of many systematic errors associated with supports. The measured value was G = (6.6873 +/- 0. 0094) x 10(-11) m3 kg-1 sec-2.     

Effects of glucosamine hydrochloride and chondroitin sulphate, alone and in combination, on normal and interleukin-1 conditioned equine articular cartilage explant metabolism

REASONS FOR PERFORMING STUDY: Clinical trials in human and veterinary literature have documented the benefits of oral nutraceutical joint supplements containing glucosamine (GU) and chondroitin sulphate (CS) to treat mild to moderate osteoarthritis, but the effects of these components have not yet been conclusively determined. OBJECTIVES: To assess varying dosages of GU and CS on normal and interleukin-1alpha (IL-1) conditioned equine cartilage explants and rationalise the use of these products. HYPOTHESIS: Treatment would not be detrimental to cartilage metabolism and higher dosages and the combination of GU and CS would be more beneficial than lower dosages and. GU or CS alone. METHODS: Articular cartilage explants collected from the femoral trochlea and condyles were cultured in normal and IL-1 conditioned media. Treatment groups included 0, 12.5, 25,125 and 250 microg/ml concentrations of GU alone, CS alone, or GU+CS in combination. Glycosaminoglycan (GAG) synthesis and total GAG content in the explants and media were analysed. RESULTS: There were no detrimental effects of GU, CS or GU+CS on cartilage metabolism. High dosages of GU+CS reduced total GAG release into the media (degradation). CONCLUSIONS: Our results suggests that GU+CS may prevent cartilage GAG degradation. POTENTIAL RELEVANCE: The combination of GU and CS may be more effective in preventing or treating osteoarthritis in horses than either product alone.     

Effects of Cryopreservation on Bull Spermatozoa Distribution in Morphometrically Distinct Subpopulations

Assisted sperm morphometry analysis (ASMA) was used in this study to determine the effects of cryopreservation on bull spermatozoa distribution in morphometrically distinct subpopulations. Ejaculates were collected from five bulls and were divided. One portion was diluted at 30 degrees C in a skim milk-egg yolk medium, containing glycerol. A microscope slide was prepared from single extended sperm samples prior to freezing. The remainder of each sample was frozen in nitrogen vapours. After thawing, sperm smears were prepared as described above. All slides were air dried and stained with Hemacolor. The sperm-head dimensions for a minimum of 200 sperm heads were analysed from each sample by means of the Sperm-Class Analyser (SCA), and the mean measurements recorded. Our results showed that applying the ASMA technology and multivariate cluster analyses, it was possible to determine that three separate subpopulations of spermatozoa with different morphometric characteristics coexist in bull ejaculates (large, average and small spermatozoa). The mean values of each sperm head dimension among the three subpopulations of spermatozoa were significantly different (p < 0.001). Besides, there were significant (p < 0.001) differences in the distribution of these three sperm subpopulations between fresh and thawed samples. Thus, the percentage of representation of the subpopulation that includes those spermatozoa whose dimensions are the biggest, decreased from 52.06% in extended fresh samples to 15.51% in the thawed ones. Contrarily, the percent of representation of the subpopulation containing the smallest spermatozoa, increased from 8.70% in extended fresh samples to 34.04% in the thawed ones. In conclusion, the present study confirms the heterogeneity of sperm head dimensions in bull semen, heterogeneity that vary through the cryopreservation procedure.     

Natriuretic peptide system regulation in granulosa cells during follicle deviation and ovulation in cattle

Natriuretic peptides (NPs) are known to regulate reproductive events in polyovulatory species, but their function and regulation in monovulatory species remain to be fully characterized. Using a well‐established in vivo model, we found that bovine granulosa cells from follicles near the deviation stage express mRNA for the three NP receptors (NPR1, NPR2 and NPR3), but not for NP precursors (NPPA, NPPB and NPPC). The abundance of NPR3 mRNA was higher in dominant compared to subordinate follicles at the expected time of follicular deviation. After deviation, mRNA for all NP receptors was significantly more abundant in the dominant follicle. Intrafollicular inhibition of oestrogen receptors downregulated NPR1 mRNA in dominant follicles. In granulosa cells from preovulatory follicles, NPPC mRNA increased at 3 and 6 h after systemic GnRH treatment, but decreased at 12 and 24 h to similar levels observed in samples collected at 0 h. After GnRH treatment, NPR1 mRNA was upregulated at 24 h, NPR3 mRNA gradually decreased after 3 h, while NPR2 mRNA was not regulated. The mRNA expression of the enzyme FURIN increased at 24 h after GnRH treatment. These findings revealed that the expression of mRNA encoding important components of the NP system is regulated in bovine granulosa cells during follicular deviation and in response to GnRH treatment, which suggests a role of NP system in the modulation of these processes in monovulatory species.     

Effects of intravenous lidocaine on the minimum alveolar concentration of isoflurane in cats

Lidocaine has been reported to decrease the minimum alveolar concentration (MAC) of inhalation anesthetics in several species and has been used clinically to reduce the requirements for other anesthetic drugs. This study examined the effects of intravenous lidocaine on isoflurane MAC in cats. Six cats were studied. In experiment 1, the MAC of isoflurane was determined. An intravenous bolus of lidocaine 2 mg kg^–1 was then administrated and venous plasma lidocaine concentrations measured to determine pharmacokinetic values. In experiment 2, lidocaine was administered to achieve target plasma concentrations between 1 and 11 μg mL^–1 and the MAC of isoflurane was determined in triplicate at each lidocaine plasma concentration, using the tail‐clamp method. End‐tidal isoflurane concentration was determined using a calibrated infrared analyzer. Systolic blood pressure (Doppler), SpO2 and end‐tidal PCO2 (calibrated Raman spectrometer) were measured prior to each MAC determination. Body temperature was maintained between 38.5 and 39.5 °C by supplying external heat as needed. MAC values at the different lidocaine plasma concentrations were analyzed by a repeated measures ANOVA , using the Huynh–Feldt correction. The MAC of isoflurane in these cats was 2.21 ± 0.17. For the target concentrations of 1, 3, 5, 7, 9, and 11 μg mL^–1, the actual lidocaine plasma concentrations was 1.06 ± 0.12, 2.83 ±0.39, 4.93 ± 0.64, 6.86 ± 0.97, 8.86 ± 2.10, and 9.84 ± 1.34 μg mL^–1, respectively. At these target concentrations, the MAC of isoflurane was 2.14 ± 0.14, 1.88 ± 0.18, 1.66 ± 0.16, 1.47 ±0.13, 1.33 ± 0.23, and 1.06 ± 0.19%, respectively. Lidocaine, at target plasma concentrations of 1, 3, 5, 7, 9, and 11 μg mL^–1, linearly decreased isoflurane MAC by –6 to 6, 7 to 28, 19 to 35, 28 to 45, 29 to 53, and 44 to 59%, respectively. Lidocaine significantly dose‐dependently and linearly decreases the requirements for isoflurane in cats. No ceiling effect was observed within the range of plasma concentrations studied.     

Multivariate Cluster Analysis Regression Procedures as Tools to Identify Motile Sperm Subpopulations in Rabbit Semen and to Predict Semen Fertility and Litter Size

Computerized motility analysis (CASA) shows that four separate subpopulations of spermatozoa with different motility characteristics co-exist in rabbit ejaculates. There were significant (p < 0.01) differences in the distribution of these subpopulations among separate genetic lines, total sperm abnormalities and the percentage of altered acrosomes. Furthermore, logistic and linear multivariate regressions among several parameters of rabbit semen quality analysis were tested for use as predictive tools for the fertilizing ability of a specific artificial insemination semen sample. Logistic regression analysis rendered two mathematical, significant (p < 0.01) models: one between sperm viability and conception rate and the other between total sperm abnormalities and conception rate. Multiple linear regression analyses also yielded some significant relationships between both fertility (p < 0.001) and litter size (p < 0.05), with respect to some semen characteristics. Our results support the hypothesis that the predictive in vivo fertility use of the standard rabbit semen quality analysis coupled with a CASA determination could be reasonably achieved by applying linear and logistic regression analyses among several parameters of rabbit semen quality analysis.     

Oxidized dietary fat,alkaline phosphatase concentrations and performance in racing greyhounds

Racing dogs are often fed raw meat. Raw meat may become oxidized because it contains no preservatives but few studies have examined the effect of feeding oxidized food to dogs. This study was originally designed to determine the effect of different concentrations of dietary fat on greyhound performance. After the experiment had been completed, however, it was discovered that the peroxide values (PV) of both diets were elevated indicating that fat oxidation had been present. This study was considered to have value, therefore, because it compared performance and blood parameters in eight trained Greyhounds fed either a high fat moderately oxidized (HFMO) diet (43%ME fat with PV of 44 mEq/kg) or a medium fat highly oxidized (MFHO) diet (31%ME fat with PV of 211 mEq/kg) for 8 weeks per diet in a randomized cross‐over design. Dogs were raced over 500 m twice weekly. Race times over the last 4 weeks of each diet period and blood parameters before racing during the last week of each diet period were compared. Dogs fed the MFHO food ran 0.04 m/s slower (p = 0.06) and serum alkaline phosphatase concentrations were higher (149 vs. 56 U/L; p < 0.0001) than in dogs fed the HFMO diet. Further evaluation is needed to determine whether lower dietary fat or increased oxidation was responsible for the altered performance but oxidation of the food should be considered as one possible explanation for an increase in serum alkaline phosphatase during a diet trial.