Release of Interface Confined Water Significantly Improves Dentin Bonding

Water residue and replacement difficulty cause insufficient adhesive infiltration in demineralized dentin matrix (DDM), which produces a defective hybrid layer and thus a bonding durability problem, severely plaguing adhesive dentistry for decades. In this study, we propose that the unique properties of a highly hydrated interface of the porous DDM can give rise to 1 new type of interface, confined liquid water, which accounts for most of the residue water and may be the main cause of insufficient infiltration. To prove our hypothesis, 3 metal ions with increasing binding affinity and complex stability (Na⁺, Ca²⁺, and Cu²⁺) were introduced respectively to coordinate negatively charged groups such as -PO₄^3-, -COO^- abundant in the DDM interface. Strong chelation of Ca²⁺ and Cu²⁺ rapidly released the confined water, significantly improving penetration of hydrophobic adhesive monomers, while Na⁺ had little effect. A significant decrease of defects in the hybrid layer and a much decreased modulus gap between the hybrid layer and the adhesive layer greatly optimized the microstructure and micromechanical properties of the tooth-resin bonding interface, thus improving the effectiveness and durability of dentin bonding substantially. This study paves the way for a solution to the core scientific issue of contemporary adhesive dentistry: water residue and replacement in dentin bonding, both theoretically and practically.

High throughput in vitro and in vivo screening of inland waters of Southern California

The impact of unmonitored contaminants, also known as contaminants of emerging concern (CECs), on freshwater streams remains largely uncharacterized. Water samples from 31 streams representing urban, agricultural and undeveloped (i.e., open space) land use in Southern California (USA) were analyzed for in vitro and in vivo bioactivity. The extent and magnitude of bioactivity screened using endocrine-responsive cell bioassays and a fish embryo screening assay were low. In contrast, a wider gradient of responses for the aryl hydrocarbon receptor (AhR) assay was observed, which was negatively correlated with a measure of benthic community structure. Both aromatic and non-aromatic CECs were tentatively identified in these samples, but polycyclic aromatic hydrocarbons (PAHs), known AhR agonists in urban environments, were not present at detectable levels. These results suggest that a combination of in vitro and in vivo show potential as screening techniques for biological condition in situ, but that more advanced, comprehensive analytical methods are needed to identify bioactive contaminants.

Transient expression of hepatitis B virus surface antigen (HBsAg) and human erythropoietin (hEPO) genes in milk after direct introduction into ewe

The ability to deliver nonviral DNA directly into animals would provide major practical and economic benefits. To pursue this potential, as a preliminary approach, the expression in mammary epithelial cells with nonviral DNA ending HBsAg and hEPO was investigated by in vivo delivery directly into mammary gland Either the bovine asl-casein-HBsAg or the WAE-hEPO gene construct was introduced into mammary glands of dm by mammary artery injection. A single injection of 10(11) copies of DNA construct was implemented for a doe. Transient expression of the constructs in milk collected from milk letdown by induction up to 19 d after injection was measured with an hEPO ELISA kit from Boehringer Mannheim (Cat. No. 1 693 417) for rhEPO, and a HBsAg-ELISA kit (Abbott Lab. USA) for rHBsAg. The treated animals showed mean concentration of recombinant molecules at 16 microg/L for rHBsAg, and 2 mg/L for rhEPO in milk.

Production of cloned goats from enucleated oocytes injected with cumulus cell nuclei or fused with cumulus cells

This study was designed to produce cloned goats from cumulus cells. Cloning donor nuclei were from cumulus cells either freshly isolated or cultured in vitro. Enucleated oocytes were either injected with cumulus cell nuclei without piezo-driven manipulator (injection method) or fused with cumulus cells (fusion method). The survival rate of cloned embryos, obtained by injection, was higher than that derived from fusion (62.7 and 45.9%, respectively). Two cloned goats were derived by fusion with in vitro cultured cumulus cells without starvation, but died shortly after natural birth, from respiratory difficulties. Their birth weights (2.23 kg and 2.03 kg) were within the normal range (2.0-2.7 kg) and postmortem analysis revealed no morphological abnormalities. The third cloned goat, derived by injection of nuclei from freshly isolated cumulus cells, weighed 3.3 kg at birth, and was 37% overweight compared with the average weight of the same species. This goat is healthy and well as this paper is being prepared. Nested PCR-RFLP analysis confirmed that all the cloned goats were derived from the donor cells.

Electronic and vibrational spectra of a series of substituted carbazole derivatives

The FTIR and FTR spectra of halogen (Cl, Br, I) substituted carbazole and their N-acetic and propionic acids have been recorded. A number of lines have been assigned on the basis of previous studies on the parent compound and by comparisons with the characteristic vibrations of their constituent structural units as well as comparing the spectra from FTIR and FTR. Some substituent-sensitive bands and characteristic bands were found. The electronic absorption spectra of these compounds in acetonitrile were also measured and are briefly discussed.

Expression of HBsAg gene in transgenic goats under direction of bovine alpha-S1 casein control sequence

An expressive construct combining hepatitis B surface antigen gene and bovine alpha-S1 casein control sequence (a 16-kb fragment), lambda 106, was made successfully using DNA recombination technology. The construct was then introduced into fertilized goat eggs with a transgenic technique. As the eggs developed into adults which, in turn, began to secrete milk after parturition, ELISA assay demonstrated HBsAg in the milk, thus showing successful expression of the construct in the mammary gland of the G0 transgenic goats and the secretion of the expression product into the milk.

Analysis of Chinese isolates of Trichinella spiralis by molecular biotechnology

OBJECTIVE

To investigate the relationships among Trichinella spiralis isolates obtained from different hosts and geographical regions in China.

MATERIALS AND METHODS

Six isolates of Trichinella spiralis obtained from Changchun, Tianjin, Xi'an, Henan and Yunnan were detected. All the isolates were collected from pigs or dogs. Restriction fragment length polymorphism (RFLP), isoenzyme electrophoresis and soluble protein analysis were used.

RESULTS

Distinctive banding patterns in restriction maps were seen between Changchun and other isolates studied. A cloned specific repetitive DNA sequence (1.12 kb) from Changchun isolate was then selected to prepare probe for Southern blotting of DNA fragments. The hybridizing banding patterns among the isolates were different and only the Changchun isolate showed the 1.12 kb band. The Changchun isolate was also distinguishable from the other isolates in isoenzyme patterns of GP1, G6PD, HK, 6PGDH and AK, as well as in isoelectric focusing electrophoresis where the Changchun isolate presented a specific band at 4.1 P1.

CONCLUSIONS

There are at least two different biological types of Trichinella spiralis in China and the differences between them may be attributed to different geographical origins and/or different hosts.

Restriction fragment length polymorphism (RFLP) analysis of genomic DNA of 5 strains of Trichinella spiralis in China

Five restriction endonucleases were used to digest genomic DNA from 5 isolates of Trichinella spiralis obtained from Changchun, Tianjin, Xian, Henan and Yunnan. All the isolates were secured from pigs except the Changchun strain which came from dog. The DNA fragments digested by endonuclease were separated by agarose gel electrophoresis. The Changchun isolate had a EcoRI band at 1.12kb and a DraI band at 1.97kb which were unique to this isolate. A cloned specific repetitive DNA sequence (1.12kb) from the Changchun strain was selected to prepare a probe for the Southern blotting of EcoRI restriction DNA fragments for the 5 isolates. The 1.12kb hybridizing band did not appear except in the Changchun isolate. These results seem to indicate that there are differences between the isolates obtained from hosts in different geographical regions.

Cloning, mapping, and sequencing of 3' and its flanking region of bovine alpha-s1 casein gene

A positive clone was isolated from a bovine genomic library in EMBL3 with the probe of alpha-s1 casein gene cDNA. The results from both restriction endonuclease digestion and Southern hybridization probed with the upstream and downstream fragments from the termination codon of bovine alpha-s1 casein gene cDNA suggested that the clone contained 3.5 kb downstream and 10.2 kb upstream fragments from the termination codon of alpha-s1 casein gene. Some divergences in restriction endonucleases sites, a few deletions, and many point mutations were found in introns and exons when compared with those which were published.

Constructions of gene libraries of Rana nigromaculata and Mus musculus with cosmid pHC79

Gene libraries of Rana nigromaculata and Mus musculus (C57J6) have been constructed by the cosmid system developed by Collins using BamHl and Pstl as cloning restriction enzymes. A simplified formula, which is a modification of Clarke and Carbon derived from approximation, was used for calculating the number of colonies or recombinants necessary for the construction of a gene library. Pro+ and leu+ complementary to the recipient cells (HB101) with the genetic constitution of pro- and leu- have been selected from the BamH1 gene libraries of both Rana nigromaculata and the mouse in the present work.