PRRX1+MSCs Enhance Mandibular Regeneration during Distraction Osteogenesis

Bone defect (BD) caused by trauma, infection, congenital defects, or neoplasia is a major cause of physical limitation. Distraction osteogenesis (DO) is a highly effective procedure for bone regeneration, while the concrete mechanism remains unknown. In this study, canine DO and BD models of the mandible were established. The results of micro-computed tomography and histological staining revealed that DO led to an increased mineralized volume fraction and robust new bone formation; in contrast, BD demonstrated incomplete bone union. Mesenchymal stem cells (MSCs) from DO and BD calluses were isolated and identified. Compared with BD-MSCs, DO-MSCs were found to have a stronger osteogenic capability. Single-cell RNA sequencing analysis was further performed to comprehensively define cell differences between mandibular DO and BD calluses. Twenty-six clusters of cells representing 6 major cell populations were identified, including paired related homeobox 1-expressing MSCs (PRRX1⁺MSCs), endothelial cells (ECs), T cells, B cells, neutrophils, and macrophages. Interestingly, 2 subpopulations in PRRX1⁺MSCs in the DO group were found to express the marker of neural crest cells (NCCs) and were associated with the process of epithelial-mesenchymal transition. The immunofluorescence assay was performed to further corroborate these results in vivo and in vitro, experimentally validating that continuous distraction maintained the PRRX1⁺MSCs in an embryonic-like state. Finally, we used CRISPR/Cas9 to knock out (KO) PRRX1 in the context of DO, which significantly blunted the capability of jawbone regeneration, resulting in a diminished NCC-like program and reduction of new bone volume. In addition, the ability of osteogenesis, cell migration, and proliferation in cultured PRRX1^KO MSCs was inhibited. Taken together, this study provides a novel, comprehensive atlas of the cell fates in the context of DO regeneration, and PRRX1⁺MSCs act essential roles.

Effects of dietary copper on growth, digestive, and brush border enzyme activities and antioxidant defense of hepatopancreas and intestine for young grass carp (Ctenopharyngodon idella)

To investigate the effects of dietary copper (Cu) on fish growth, digestive and absorptive enzyme activities, and antioxidant status in the hepatopancreas and intestine, young grass carp (Ctenopharyngodon idella) (282±2.8 g) were fed six diets containing 0.74 (basal diet), 2.26, 3.75, 5.25, 6.70, and 8.33 mg Cu /kg diet for 8 weeks. Results showed that percentage weight gain (PWG) and feed intake were increased with dietary Cu levels up to 3.75 mg/kg diet. In addition, the positive effects of dietary Cu at a level 3.75 or 5.25 mg/kg diet on trypsin, chymotrypsin, and lipase activities in the hepatopancreas and of Na(+), K(+)-ATPase, alkaline phosphatase, creatine kinase, and γ-glutamyl transpeptidase activities in three intestine segments produced significantly (P<0.05) better feed efficiency (FE). However, amylase activity in the hepatopancreas was decreased by dietary Cu levels up to 3.75 mg/kg diet (P<0.05). In addition, dietary Cu at 3.75 or 5.25 mg/kg diet decreased malondialdehyde and protein carbonyl content partly by significantly (P<0.05) increasing the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, and glutathione content in the hepatopancreas and intestine. Collectively, dietary Cu improved growth and digestive and absorptive capacity and decreased lipid peroxidation and protein oxidation partly by enhancing antioxidant defense in the hepatopancreas and intestine. The dietary Cu requirement for PWG, plasma ceruloplasmin activity, and FE of young grass carp (282-688 g) were 4.78, 4.95, and 4.70 mg/kg diet, respectively.

[Yeast (Saccharomyces cerevisiae) secretory expression vector maintained stably in Pro3+ transformants in rich medium]

A yeast (Saccharomyces cerevisiae) secretory expression vector containing PRO3 gene was constructed (pCBy310). beta HCG(Human choriogonadotropin beta subunit)-cDNA was inserted into pCBy310 to form a recombinant plasmid pCBy314. Since yeast proline auxotroph will not survive in rich medium (YPD), YPD could be used as a selection pressure, and pCBy314 could be maintained mitotically stable in transformants of yeast Pro3- auxotroph (MB299-7A) in rich medium. At an improved, yet not optimized cultural condition, the expression of beta HCG in culture medium was 650 micrograms/L. Our results showed not only that YPD could be used as a selection medium, but also that yeast grew better in YPD so as to increase the gene expression product, and that the component of YPD was simple and cheap. Our data suggested that PRO genes might be used widely in constructing vectors to clone and express foreign genes in yeast so that rich medium can be used as a selection pressure for direct selection.

[Pharmacokinetics of moracizine and moracizine sulfoxide in healthy volunteers]

The pharmacokinetics of moracizine (Mor) and moracizine sulfoxide (Mor-SO) determined by reversed phase HPLC was reported. The data in 6 volunteers after a single oral dose (600 mg) showed an one-compartment open model. The peak concentration in plasma (2.1 +/- 0.4 micrograms.ml-1) of Mor reached within 1-2 h. The Mor-SO concentration in plasma was much lower (0.19 +/- 0.06 micrograms.ml-1) than that of Mor, but its elimination T1/2 (2.3 +/- 1.0 h) was similar to that of Mor (1.5 +/- 1.0 h). The recoveries of Mor, Mor-SO, moracizine sulfone (Mor-SO2) in urine within 48 h were 0.07%, 0.25%, and 0.06% of the total dose, respectively. The Mor and Mor-SO concentration ranges in plasma for 9 arrhythmic patients after 2-wk therapeutic trial were 0.09 +/- 0.07 to 0.9 +/- 0.5 microgram.ml-1 and 0.040 +/- 0.023 to 0.15 +/- 0.06 micrograms.ml-1, respectively. These results suggested that cumulative doses would not result in accumulation of the drug and the anti-arrhythmic effect of Mor-SO might not be realized.

Pharmacokinetics and relative bioavailability of tablet of micronized glibenclamide in 4 Chinese healthy men

Pharmacokinetic characteristics and relative bioavailability of the regular preparation (RG) and micronized preparation (MG) of glibenclamide (Gli) were studied in 4 Chinese healthy men. Each volunteer entered 2 consecutive experiments at the same dose (10.5 mg) of RG and MG tablets given orally. Blood samples were drawn before and 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 h after po. A selective HPLC method with a uv spectrophotometric detector (sensitivity: 16 ng.ml-1) was established for determining serum Gli concentration. Cmax for RG was 212 +/- 41 ng.ml-1, for MG 529 +/- 73 ng.ml-1. Tmax for RG and MG were 3.5 +/- 0.6 and 2.2 +/- 0.3 h, respectively. The relative oral bioavailability of MG was found to be 77%, increased approximately 1.7-fold that of RG. The other pharmacokinetic parameters (Vd, Cl, T1/2) were substantially the same after ingestion of GR and MG.

Debrisoquine hydroxylation and sulfamethazine acetylation in a Chinese population

Both debrisoquine hydroxylation and sulfamethazine acetylation phenotypes were studied in the same native Chinese population. Debrisoquine hydroxylation status was determined by HPLC assay of debrisoquine metabolic ratio in urine after a single oral dose of 10 mg debrisoquine. Three poor metabolizers were found in 220 subjects (1.36%). One hundred and one subjects of this population previously debrisoquine phenotyped were also tested for acetylation phenotyping on a separate occasion. Their acetylation status were determined by HPLC assay of "% acetylation" after a single oral dose of 1 g sulfamethazine. Twenty (19.8%) slow acetylators were found. There were no significant association between the 2 metabolic pathways.

Purification of a protein binding to the CDEI subregion of Saccharomyces cerevisiae centromere DNA

The DNA subregions CDEI and CDEIII of Saccharomyces cerevisiae centromeres are highly conserved, and both are binding sites for proteins. We describe here the purfication of a CDEI-specific binding protein using biotin-labeled synthetic CDEI DNA coupled to streptavidin agarose. The binding properties of this 64-kilodalton (kDa) protein were characterized by competition assays and by methylation interference assays. DNA fragments with single base-pair changes at positions 7 and 8 of CDEI were less efficient competitors than fragments with nonmutated CDEI. Mutations at these positions have previously been shown to decrease centromere activity in vivo. Methylation of guanosines at either side of the 8-base-pair CDEI sequence did not interfere with binding, whereas methylation of any of the four guanosines within CDEI prevented binding. A smaller CDEI-specific binding protein of 37 kDa was also purified and characterized. It is most likely a degradation product of the 64-kDa protein.

Disposition of ethmozine in cerebrospinal fluid and plasma of rabbits

The concentration-time profiles of ethmozine, a newly introduced anti-arrhythmic drug, in the cerebrospinal fluid (CSF) and plasma of six rabbits (New Zealand white rabbits of both sexes, 4.0-5.0 Kg) were studied after intravenous bolus administration. CSF samples at various intervals were obtained while the animal was lightly anaesthetized with intravenous thiopentone (40 mg Kg-1) and blood samples at other intervals were taken while the animal was conscious. Blood samples (1 ml) were collected from the implanted cannula of the ear artery while CSF samples (0.3 ml) were obtained from the cisterna magna. The plasma concentrations of ethmozine in six rabbits declined rapidly after intravenous injection for up to 30 min. then slowly over 12 h. Using non-compartmental analysis, the mean (+/- S.E.M.) elimination half-life, mean residence time, plasma clearance and volume of distribution at steady state were 13.9 +/- 9.2 h, 19.9 +/- 13.4 h, 2.3 Lh-1 and 26.8 +/- 7.9 L respectively. The mean CSF-plasma concentration ratios for ethmozine at 0.5, 1.0, 2.0, 4.0, 8.0 and 12.0 h were 0.17, 0.14, 0.16, 0.16, 0.23 and 0.22 respectively. The results suggest that ethmozine is able to penetrate into the CSF from the general circulation and this may be related to its adverse effects on the central nervous system.

Effect of 2-butanol and 2-butanone on rat hepatic ultrastructure and drug metabolizing enzyme activity

The effect of a single oral dose of 2-butanol (2.2 ml/kg) or 2-butanone (1.87 ml/kg) on hepatic ultrastructure and drug-metabolizing enzyme activity was studied in the rat. A 135-197% increase in acetanilide hydroxylase activity was found in rats sacrificed 12-40 h after dosing with 2-butanol or 2-butanone. A 40-h pretreatment with 2-butanone produced a 155% increase in aminopyrine N-demethylase activity. NADPH-cytochrome c reductase activity and the concentrations of cytochromes P-450 and b5 were largely unaltered 2-40 h after dosing with either agent. Electron microscopic examination of hepatocytes from rats sacrificed 16 h after 2-butanol or 2-butanone revealed a marginal increase in the prevalence of smooth endoplasmic reticulum. However, by 40 h, there was a marked proliferation of the smooth endoplasmic reticulum and reduction in rough endoplasmic reticulum in response to both agents. The most marked potentiation of CCl4 hepatotoxicity occurred when rats were pretreated with 2-butanol or 2-butanone 16 h before CCl4 administration. The coincidental finding of maximal CCl4-induced hepatic injury and elevation of microsomal xenobiotic activity within the same time frame following 2-butanol or 2-butanone supports the hypothesis that aliphatic alcohols and ketones potentiate CCl4 hepatotoxicity by enhancing biotransformation of the halocarbon to cytotoxic metabolites.

Effects of long-term exposure to environmental levels of polychlorinated biphenyls on pharmacokinetics of pentobarbital in rats

The pharmacokinetics of pentobarbital, 30mg/kg iv, were studied in untreated rats and rats pretreated with 1,5, and 25 ppm of polychlorinated biphenyls in food for up to 140 days. Environmental contaminants may contribute to variations in metabolic rates of drugs by causing enzyme induction. The objective of this work was to quantitate the effects of environmental levels of the contaminant and enzyme inducer, a polychlorinated biphenyl, on the pharmacokinetics of pentobarbital, a drug whose primary elimination route is liver metabolism. The pharmacokinetics of pentobarbital in rats could be fit to a biexponential equation of the type Cp = Ae-alpha t+ Be-beta t. After 35 days of pretreatment, only the 25-ppm-treated rats showed any significant acceleration of pentobarbital elimination. At the 70- and 140-day samplings, both the 5- and 25-ppm pretreatments showed significant acceleration of pentobarbital elimination. There were no significant effects on A, alpha, B, and Vd for any pretreatment. The beta-values for the 25-ppm-pretreated rats reached a constant value from the 35-day pretreatment period onward. A calculation of total body clearance suggested that pentobarbital elimination in those rats had approached portal blood flow rate-limited metabolism.