CRISPR/Cas9-mediated mutation of PHEX in rabbit recapitulates human X-linked hypophosphatemia (XLH)

X-linked hypophosphatemia (XLH) is the most common cause of inheritable rickets, with an incidence of 1/20 000 in humans. Inactivation or mutation of the gene PHEX, a phosphate-regulating endopeptidase, leads to hypophosphatemia and defective bone mineralization in XLH patients. Presently, there is no adequate animal model for safety assessments of physiotherapies and drug screening for XLH rickets. In this study, an XLH model was generated via PHEX gene knockout (KO) through coinjection of clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9)/sgRNA mRNA into rabbit zygotes. The typical phenotypes of growth retardation, hypophosphatemia, elevated serum FGF23 and bone mineralization were observed in the PHEX KO rabbits but not in normal controls. In summary, for the first time, we have successfully obtained PHEX KO rabbits and recapitulated human XLH using the CRISPR/Cas9 system. This novel XLH rabbit model could be utilized as a drug screening model for XLH prevention and preclinical therapy.

CRISPR/Cas9-mediated GJA8 knockout in rabbits recapitulates human congenital cataracts

Cataracts are the leading cause of vision loss in the world, although surgical treatment can restore vision in cataract patients. Until now, there have been no adequate animal models for in vivo studies of artificial lens safety and drug interactions. Genetic studies have demonstrated that GJA8 is involved in maintaining lens opacity and proper lens development. In this study, a cataract model with GJA8 gene knockout was developed via co-injection of Cas9/sgRNA mRNA into rabbit zygotes. Our results showed that gene mutation efficiency in the GJA8 locus reached 98.7% in embryos and 100% in pups, demonstrating that the Cas9/sgRNA system is a highly efficient tool for gene editing in rabbits. In agreement with other studies, our genetic and histology results showed that impaired GJA8 function caused microphthalmia, small lens size and cataracts. In summary, our novel rabbit model of cataracts will be an important drug-screening tool for cataract prevention and treatment.

Faithful expression of imprinted genes in donor cells of SCNT cloned pigs

To understand if the genomic imprinting status of the donor cells is altered during the process of SCNT (somatic cell nuclear transfer), cloned pigs were produced by SCNT using PEF (porcine embryonic fibroblast) and P-PEF (parthenogenetic-PEF) cells as donors. Then, the gene expression and methylation patterns of H19, IGF2, NNAT and MEST were compared between PEF vs. C-PEF (cloned-PEF), P-PEF vs. CP-PEF (cloned-P-PEF), respectively. Taken together, the results revealed that there was no significant difference in the expression of imprinted genes and conserved genomic imprints between the donor and cloned cells.

X-ray Study of Human Dental Tissues Affected by Erythroblastosis Fetalis

Numerous diseases are known to cause microstructural alteration of dental tissues structure. One type in particular is associated with neonatal jaundice and circulation of bilirubin in blood at high concentration due to increased hemolysis in conditions such as erythroblastosis fetalis, septicemia, biliary atresia, and other causes of hyperbilirubinemia. In those conditions, the products of the catabolism of hemoglobin end up deposited in various tissues, including teeth, where they can present clinically as visibly stained brown/green teeth. There is almost no information on the nature or extent of the structural changes taking place in these conditions. Here, advanced nondestructive wide-angle synchrotron X-ray scattering techniques combined with scanning microscopy methods were used to investigate for the first time the ultrastructure of the dental hard tissues in an archival case of intrinsically pigmented green teeth. Despite no obvious elemental variation across the pigmented tissue region, the high-resolution crystallographic properties probed by wide-angle synchrotron X-ray scattering revealed an ultrastructural variation (orientation, particle size, and lattice parameter of hydroxyapatite crystallites) associated with a pigmentation line in dentine and with a distinct neonatal line in enamel.

Effect of FK506 in reducing scar formation by inducing fibroblast apoptosis after sciatic nerve injury in rats

We previously demonstrated that FK506, a generally applied immunosuppressant in organ transplantation, could promote peripheral nerve regeneration through reducing scar formation. However, little is known about how FK506 reduces scar formation. Herein we investigated the influence of FK506 on fibroblast proliferation and its correlation with scar formation after sciatic nerve injury in rats, and further explored the effect of FK506 on fibroblast proliferation and apoptosis in vitro. Masson staining and immunohistochemistry revealed that scar area and fibroblast number in the nerve anastomosis of sciatic nerve-injured rats were significantly reduced after FK506 administration. The scar area had a significant positive correlation with the fibroblast number, as detected by linear correlation analysis. CCK-8 assay and flow cytometry indicated that FK506 also inhibited proliferation and induced apoptosis of fibroblasts in vitro. It was primarily phosphorylation of JNK and ERK that were activated during the apoptosis of fibroblast. Pretreatment of cells with JNK inhibitor, SP600125, or ERK inhibitor, PD98059, could inhibit FK506-induced fibroblast apoptosis, respectively. Moreover, simultaneous application of both inhibitors had additive roles in cell protection from apoptosis. These results suggest that FK506-induced fibroblast apoptosis contributes to the suppression of fibroblast proliferation and then results in the reduction of scar formation in sciatic nerve-injured rat, and that JNK and ERK are involved in FK506-induced fibroblast apoptosis.

One-stage pedicled omentum majus transplantation into thoracic cavity for treatment of chronic persistent empyema with or without bronchopleural fistula

OBJECTIVE

Assessment of the present results of surgical treatment for chronic persistent empyema with or without bronchopleural fistula (BPF) using one-stage pedicled omentum majus transplantation into the thoracic cavity.

METHODS

From November 1979 to December 1996, 50 patients with chronic persistent empyema were treated by pedicled omentum majus transplanted into the thoracic cavity. There were 35 men and 15 women, and the age range was 15-58 years. Empyema had been present for 0.5-18 years. Twenty-six of 35 cases with chronic tuberculous empyema and six of 15 cases with chronic bacterial empyema suffered from concomitant BPF (n = 32). In the latter, the most common organisms were Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli.

RESULTS

There were no perioperative deaths. Two cases had a significant air leak on the first postoperative day. One of them underwent rethoractomy 30 h after the initial operation to stop the fistula using intrathoracic omentum. Thoracic dead space disappeared in most of the operated cases and a sterilized dry cavity remained in some cases.

CONCLUSIONS

One-stage pedicled omentum majus transposition is a safe and easy procedure for chronic persistent empyema and BPF, it breaks down residual or recurrent inflammatory foci mechanically and closes the BPF effectively with minimal deformity of the chest wall.