Genetic correlations between the cumulative pseudo-survival rate, milk yield, and somatic cell score during lactation in Holstein cattle in Japan using a random regression model.

Trends in genetic correlations between longevity, milk yield, and somatic cell score (SCS) during lactation in cows are difficult to trace. In this study, changes in the genetic correlations between milk yield, SCS, and cumulative pseudo-survival rate (PSR) during lactation were examined, and the effect of milk yield and SCS information on the reliability of estimated breeding value (EBV) of PSR were determined. Test day milk yield, SCS, and PSR records were obtained for Holstein cows in Japan from 2004 to 2013. A random subset of the data was used for the analysis (825 herds, 205,383 cows). This data set was randomly divided into 5 subsets (162-168 herds, 83,389-95,854 cows), and genetic parameters were estimated in each subset independently. Data were analyzed using multiple-trait random regression animal models including either the residual effect for the whole lactation period (H0), the residual effects for 5 lactation stages (H5), or both of these residual effects (HD). Milk yield heritability increased until 310 to 351 d in milk (DIM) and SCS heritability increased until 330 to 344 DIM. Heritability estimates for PSR increased with DIM from 0.00 to 0.05. The genetic correlation between milk yield and SCS increased negatively to under -0.60 at 455 DIM. The genetic correlation between milk yield and PSR increased until 342 to 355 DIM (0.53-0.57). The genetic correlation between the SCS and PSR was -0.82 to -0.83 at around 180 DIM, and decreased to -0.65 to -0.71 at 455 DIM. The reliability of EBV of PSR for sires with 30 or more recorded daughters was 0.17 to 0.45 when the effects of correlated traits were ignored. The maximum reliability of EBV was observed at 257 (H0) or 322 (HD) DIM. When the correlations of PSR with milk yield and SCS were considered, the reliabilities of PSR estimates increased to 0.31-0.76. The genetic parameter estimates of H5 were the same as those for HD. The rank correlation coefficients of the EBV of PSR between H0 and H5 or HD were greater than 0.9. Additionally, the reliabilities of EBV of PSR of H0 were similar to those for H5 and HD. Therefore, the genetic parameter estimates in H0 were not substantially different from those in H5 and HD. When milk yield and SCS, which were genetically correlated with PSR, were used, the reliability of PSR increased. Estimates of the genetic correlations between PSR and milk yield and between PSR and SCS are useful for management and breeding decisions to extend the herd life of cows.

Genetic analysis of the cumulative pseudo-survival rate during lactation of Holstein cattle in Japan by using random regression models.

Longevity is a crucial economic trait in the dairy farming industry. In this study, our objective was to develop a random regression model for genetic evaluation of survival. For the analysis, we used test-day records obtained for the first 5 lactations of 380,252 cows from 1,296 herds in Japan between 2001 and 2010; this data set was randomly divided into 7 subsets. The cumulative pseudo-survival rate (PSR) was determined according to whether a cow was alive (1) or absent (0) in her herd on the test day within each lactation group. Each lactation number was treated as an independent trait in a random regression multiple-trait model (MTM) or as a repeated measure in a random regression single-trait repeatability model (STRM). A proportional hazard model (PHM) was also developed as a piecewise-hazards model. The average (± standard deviation) heritability estimates of the PSR at 365 d in milk (DIM) among the 7 data sets in the first (LG1), second (LG2), and third to fifth lactations (LG3) of the MTM were 0.042±0.007, 0.070±0.012, and 0.084±0.007, respectively. The heritability estimate of the STRM was 0.038±0.004. The genetic correlations of PSR between distinct DIM within or between lactation groups were high when the interval between DIM was short. These results indicated that whereas the genetic factors contributing to the PSR between closely associated DIM would be similar even for different lactation numbers, the genetic factors contributing to PSR would differ between distinct lactation periods. The average (± standard deviation) effective heritability estimate based on the relative risk of the PHM among the 7 data sets was 0.068±0.009. The estimated breeding values (EBV) in LG1, LG2, LG3, the STRM, and the PHM were unbiased estimates of the genetic trend. The absolute values of the Spearman's rank correlation coefficients between the EBV of the relative risk of the PHM and the EBV of PSR at 365 DIM for LG1, LG2, LG3, and the STRM were 0.75, 0.87, 0.91, and 0.93, respectively. These results indicated that the EBV of PSR could predict the genetic contribution to survival. The EBV based on the PSR of the STRM was highly correlated with that of the MTM (0.83-0.96). Furthermore, the calculation load of the STRM was lighter than that of the MTM because the rank of the matrix of the STRM was smaller than that of the MTM. These results indicated that the STRM is an appropriate model for estimating survivability by using random regression models.

PGE2 signal via EP2 receptors evoked by a selective agonist enhances regeneration of injured articular cartilage.

OBJECTIVE: The effect of the prostaglandin E2 (PGE2) signal through prostaglandin E receptor 2 (EP2) receptors on the repair of injured articular cartilage was investigated using a selective agonist for EP2. METHODS: Chondral and osteochondral defects were prepared on the rabbit femoral concave in both knee joints, and gelatin containing polylactic-co-glycolic acid microspheres conjugated with or without the EP2 agonist was placed nearby. Animals were sacrificed at 4 or 12 weeks post-operation, and regenerated cartilage tissues and subchondral structure remodeling were evaluated by histological scoring. The quality of regenerated tissues was also evaluated by the immunohistochemical staining of EP2, type II collagen, and proliferating cell nuclear antigen (PCNA). As an evaluation of side effects, the inflammatory reaction of the synovial membrane was analyzed based on histology and the mRNA expression of matrix metalloproteinase3 (MMP3), tissue inhibitor of metalloproteinase 3 (TIMP3), and interleukin-1 beta (IL-1 beta). Also, the activity of MMP3 and the amount of tumor necrosis factor-alpha (TNF-alpha) and C-reactive protein in joint fluid were measured. RESULTS: In both models, the EP2 agonist enhanced the regeneration of the type II collagen-positive tissues containing EP2- and PCNA-positive chondrocytes, and the histological scale of regenerated tissue and subchondral bone was better than that of on the control side, particularly at 12 weeks post-operation. No inflammatory reaction in the synovial membrane was observed, and no induction of pro-inflammatory cytokines was found in joint fluid. CONCLUSION: Selective stimulation of the PGE2 signal through EP2 receptors by a specific agonist promoted regeneration of cartilage tissues with a physiological osteochondral boundary, suggesting the potential usefulness of this small molecule for the treatment of injured articular cartilages.

Estimation of heritability and genetic correlation for behavioural responses by Gibbs sampling in the Thoroughbred racehorse.

Genetic variation of the behaviour of racehorses is one of the major concerns for racehorse breeders. In this study, the heritabilities of behavioural responses to the inspections of conjunctiva, auscultation and blood sampling and the genetic correlations among them were estimated in the Thoroughbred racehorse. The estimation was done with Bayesian analysis with Gibbs sampling based on the univariate or bivariate threshold animal models. The behavioural responses were scored with four categories at the first entrance quarantine in Miho Training Center of Japan Racing Association from 1993 to 1995. The behavioural responses were treated as categorical or binary traits, with both showing similar results. The estimated heritabilities were in the range of 0.23-0.28, suggesting a genetic component in the variation on these traits. The estimated genetic correlations among the traits were very high (approximately 0.9), suggesting that these behavioural responses may be measures of the same trait. Because of the high genetic correlations, repeatability threshold model was applied assuming the responses to be a genetically identical trait measured with three different tests. The estimated heritabilities (approximately 0.23) were at the lower bound of the former estimates. The revealed high repeatabilities (0.97-0.98) suggest a strong contribution of the individual temperament on the behaviour of racehorses.

Ocular absorption of Pz-peptide and its effect on the ocular and systemic pharmacokinetics of topically applied drugs in the rabbit.

PURPOSE: To determine the corneal and conjunctival penetration of 4-phenylazobenzyloxycarbonyl-L-Pro-L-Leu-Gly-L-Pro-D-Arg (Pz-peptide) and to evaluate its effect on the corneal and conjunctival penetration of hydrophilic solutes as well as on the ocular and systemic absorption of topically applied atenolol and propranolol in the rabbit. The hydrophilic solutes were mannitol, fluorescein, FITC-dextran 4,000, and FITC-dextran 10,000. METHODS: Drug penetration across the rabbit cornea and conjunctiva was evaluated using the modified Ussing chamber. Ocular and systemic absorption of topically applied atenolol and propranolol was evaluated by analyzing the drug concentration in various anterior segment tissues at 45 min and in the blood over 240 min, respectively, following topical instillation of 25 microl of 20 mM atenolol or propranolol solution to the rabbit eye. RESULTS: The conjunctiva was 29 times more permeable than the cornea to 3 mM Pz-peptide. Conjunctival Pz-peptide transport was 1.7 times more extensive in the mucosal-to-serosal than in the opposite direction, whereas corneal Pz-peptide transport showed no directionality. The apparent permeability coefficient of Pz-peptide across the cornea and the conjunctiva increased over the 1-5 mM range, suggesting that Pz-peptide enhanced its own transport across both epithelial tissues. The cornea appeared to be more sensitive than the conjunctiva to the penetration enhancement effect of Pz-peptide. Thus, whereas Pz-peptide elevated the corneal transport of mannitol, fluorescein, and FD4 by 50%, 57%, and 106%, respectively, it did not affect the conjunctival transport of mannitol and fluorescein, while enhancing FD4 transport by only 46%. Moreover, while Pz-peptide enhanced the ocular absorption of topically applied hydrophilic atenolol, it did not affect the ocular absorption of lipophilic propranolol. Interestingly, Pz-peptide did not affect the systemic absorption of either beta adrenergic antagonist. CONCLUSIONS: Pz-peptide appears to facilitate its own penetration across the cornea and the conjunctiva. Pz-peptide appears to increase the ocular absorption of topically applied hydrophilic but not lipophilic drugs, while not affecting the systemic absorption of either type of drugs.

A mechanistic study on enhancement of rectal permeability to insulin in the albino rabbit.

This study was conducted mainly to investigate the relative contributions of various mechanisms by which bile salts and EDTA may improve the in vitro rectal penetration of insulin in the albino rabbit. Insulin could not cross the rectal mucosa unless Na glycocholate or other penetration enhancers were present. Penetration enhancement was attributed primarily to Na glycocholate's ability to reduce the barrier function of the rectal membrane and to increase the fraction of insulin in its monomeric form, and secondarily to Na glycocholate's ability to protect insulin from proteolysis. Na glycocholate was more effective than Na taurocholate, but less effective than Na deoxycholate and polyoxyethylene-9-lauryl ether in enhancing rectal insulin penetration. Although EDTA at 0.01 and 0.1% did not affect rectal insulin penetration, it augmented the penetration enhancement effect of 1% Na glycocholate without causing additional damage to the rectal membrane, as judged by protein release. Such an action was attributed to the synergistic effect associated with: 1) an increase in the permeability of the paracellular pathway by EDTA and 2) an increase in the proportion of insulin in the monomeric form by Na glycocholate. Results from parallel in vivo experiments have indicated that it may be possible to achieve significant penetration enhancement by using a combination of otherwise membrane-damaging penetration enhancers which act by complementary mechanisms at concentrations that are both effective and well tolerated by mucosal epithelial cells.

Phosphatidylserine as a determinant for the tissue distribution of weakly basic drugs in rats.

Interogan variation in tissue distribution of weakly basic drugs such as quinidine, propranolol, and imipramine was investigated as a function of binding to phosphatidylserine (PhS) in tissues. Tissue distributions of these drugs were determined using 10 different tissues at a steady-state plasma concentration and were expressed as tissue-to-plasma partition coefficients (Kp values). The concentration of PhS in the tissue was determined by two-dimensional thin-layer chromatography. Plotting of Kp values, except for brain, against the tissue PhS concentrations showed a linear relationship, indicating that PhS is a determinant in the interorgan variation of these tissue distributions. Further, differences in tissue distribution among the drugs was considered to be due to the difference in binding potency to PhS. Drug binding parameters to individual standard phospholipid were determined using a hexane-pH 4.0 buffer partition system. Binding was highest to PhS, and a linear relationship was found between the log nK [product of the number of binding sites (n) and the association constant (K) for PhS binding] obtained in vitro and Kp values of drugs in tissues in vivo. The empirically derived equation, Kp = 14.3 x (log nK) x (PhS conc.) - 8.09, was found to predict Kp values in vivo of weakly basic drugs. Thus, a determinant of interorgan variation in the tissue distribution of the weakly basic drugs studied was the tissue concentration of PhS and the drug binding affinity to PhS.

Role of phosphatidylserine in the cellular and subcellular lung distribution of quinidine in rats.

The role of phosphatidylserine in the cellular and subcellular lung distribution of quinidine was investigated in rats, since quinidine was found to bind preferentially to phosphatidylserine. The concentration of phosphatidylserine in the cellular and subcellular fractions was determined after separation by two-dimensional thin-layer chromatography. Selective accumulation of quinidine in vivo was observed in the alveolar macrophage at the cellular level and in the plasma membrane at the subcellular level. Both alveolar macrophages and plasma membranes were rich in phosphatidylserine compared to other fractions. When plasma levels were kept at steady state by i.v. infusion, the distribution of quinidine in the lung cellular and subcellular fractions was linearly correlated with the concentration of phosphatidylserine (r = 0.906). These results suggest that the concentration of phosphatidylserine is a dominant determinant of the cellular and subcellular lung distribution of quinidine.

Role of acidic phospholipids in tissue distribution of quinidine in rats.

The mechanism of interorgan variation in tissue distribution of quinidine was investigated from a viewpoint of binding characteristics to phospholipids and the composition of phospholipids in various tissues. The order of binding of quinidine to an individual standard phospholipid, expressed as a product of the association constant (K) and the number of binding sites (n), was: phosphatidyl ethanolamine (PhE) less than dipalmitoyl phosphatidyl choline (saturated PhC) less than or equal to phosphatidyl choline (unsaturated PhC) less than phosphatidyl inositol (PhI) less than phosphatidyl glycerol (PhG) less than phosphatidic acid (PhA) less than phosphatidyl serine (PhS). Thus, quinidine was found to bind preferentially to acid phospholipids such as PhS, PhA, PhG, and PhI. The greatest binding was obtained in PhS among the various phospholipids and was more than 300-fold that of neutral phospholipids such as PhC and PhE. The concentration of individual components of phospholipids in the lung, kidney, liver and heart was determined using a two dimensional thin-layer chromatography. The concentration of PhS, highly responsible for the quinidine binding to phospholipids in each tissue, was ranked in the following order: heart less than liver less kidney less than lung. The contribution of PhS to quinidine binding was more than 86% in all tissues. A good correlation between the concentration of PhS in each tissue and the Ct/Cp ratio in vivo was obtained (r = 0.984). Thus, it was concluded that the tissue distribution of quinidine in vivo depended on the composition of phospholipids in tissues and that a determinant of interorgan variation in the tissue distribution of quinidine was the concentration of PhS in the tissues.

A possible contribution of phospholipids in tissue distribution of quinidine in rats.

The tissue distribution of quinidine was investigated at three different steady-state plasma concentrations of quinidine in rats. The tissue distribution of quinidine (tissue-to-plasma concentration ratio, Ct/Cp) was studied in the liver, lung, kidney and heart and the highest distribution was found in the lung. Tissue binding characteristics of quinidine was determined in normal tissue homogenates and lipid-depleted tissue homogenates in vitro. No correlation was observed between the tissue bindings (product of association constant (K1) and number of binding sites (n), nK1) estimated in each normal tissue homogenate and the values of Ct/Cp in vivo. However, a marked decrease in the tissue binding of quinidine was observed in all lipid-depleted tissue homogenates, and the largest decrease was observed in the lung tissue. This result suggested that lipid may have an important role in the tissue binding of quinidine. However, no good relationship was observed between the values of Ct/Cp and the phospholipid contents in each tissue. In order to investigate the role of lipid in the tissue binding of quinidine, phospholipids extracted from each tissue were used for binding study. The phospholipids binding of quinidine (nK2) increased in the following order; heart less than liver less than kidney less than lung, and the plots of the values of Ct/Cp obtained in vivo against the binding ability of phospholipids (product of nK2 and the content of phospholipid in each tissue) gave a good linear relationship. Based on these observations, it was concluded that some species of phospholipids had an important and determining role in the tissue distribution of quinidine in vivo.

Salivary excretion of warfarin in rabbits: relationship between pharmacological effect and salivary pharmacokinetics of warfarin in rabbits.

The salivary excretion of warfarin was investigated following intravenous and oral administration to rabbits. The salivary decay curves following intravenous injection (50 mg/kg) fitted to the two-compartment open model. On the other hand, following oral administration (100 mg/kg) the disposition of warfarin fitted to the one-compartment open model. There was a good linear relationship between the warfarin concentrations in saliva and plasma. The saliva vs. plasma (S/P) ratio was approximately 0.07. A good correlation was also observed between the warfarin concentrations in saliva and plasma protein-unbound fraction. The saliva vs. plasma protein-unbound fraction (S/Pf) ratio was approximately 0.92. Therefore, salivary concentration of warfarin corresponded with plasma free warfarin concentration. Furthermore, warfarin concentration in saliva was correlated with pharmacological effect, prothrombin complex activity. These results suggested that salivary warfarin concentration which was correlated with pharmacological effect had a possibility of utilization in pharmacokinetic studies and therapeutic drug monitoring.