Promotion of peri-implant bone healing by systemically administered parathyroid hormone (1-34) and zoledronic acid adsorbed onto the implant surface

The effect of human parathyroid hormone 1-34 (PTH) and zoledronic acid (ZA) alone or in combination on bone healing in osteoporotic settings was tested using implants inserted in tibiae of ovariectomized (OVX) rats. Combination therapy promoted bone healing more than each treatment alone 12 weeks after implant insertion.

INTRODUCTION

PTH and ZA have been demonstrated to be effective on implant fixation. However, reports about the combined use of PTH and ZA for promotion of bone healing around implant in osteoporotic settings are still limited. This study aims to investigate effects of PTH+ZA on implant stabilization in OVX rats.

METHODS

Twelve weeks after bilateral ovariectomy, OVX rats randomly received implants without or with ZA (by immersion in 1 mg/ml ZA solution for 24 h). Subsequently, half of the animals from each group also received subcutaneous injections of PTH (60 μg/kg, three times a week) for 12 weeks. Thus, there were four groups: control, PTH, ZA, and PTH+ZA.

RESULTS

All treatments promoted bone healing around implant compared to control, but PTH+ZA treatment showed significantly stronger effects than PTH or ZA alone in histological, micro-CT, and biomechanical tests.

CONCLUSION

The results indicated the additive effects of PTH and ZA on implant fixation in OVX rats; it was suggested that the anabolic effect of PTH was potent and not blunted by ZA during bone healing around implant when used concurrently.

The effect of surface composition of titanium films on bacterial adhesion

We show that bacterial adhesion on titanium (Ti) films could be radically minimized by tailoring the surface chemical stoichiometry of the films. Using a dc magnetron sputtering system, Ti films with various surface compositions, such as oxide and nitride combinations, were prepared by controlling processing parameters such as cathode power, sputtering pressure and base vacuum. The surface topography of the films was observed to be smooth and similar in all the films prepared under different conditions. The order of adhesion of the oral bacterial Porphyromonas gingivalis varied with the surface chemical stoichiometry of the Ti films. Few surface stoichiometries of typical oxide nitride combination resulted in nearly nil bacterial adhesion.

Molecular analysis of hypoxanthine phosphoribosyltransferase gene deletions induced by alpha- and X-radiation in human lymphoblastoid cells

Mutations caused by exposure to X-radiation and to radon and its decay products were compared in the hprt gene of a human lymphoblastoid cell line. Thirty-one X-radiation-induced, 29 radon-induced, and 24 spontaneous mutants were recovered from cell cultures under identical conditions except for the exposure to radiation. Seven spontaneous point mutations were recovered and DNA sequenced. These mutations included three C:G-->T:A transitions. These spontaneous point mutations were located in the exon or splice donor regions of five of the nine hprt exons. Four X-radiation-induced and three radon-induced point mutations were also analyzed by DNA sequencing. The frequency of induced mutants at the D0 doses for radon and X-radiation respectively were 5 x 10(-6) and 4.5 x 10(-6). Deletions were the predominant mutations recovered from both radon- and X-irradiated cells. Eighty-one percent of the mutants from X-radiation-treated cultures, 86% of the radon-treated cultures, and 63% of the spontaneous mutants involved deletions. Deletions involving exon and intron DNA, as well as intron DNA alone, were found to inactivate the hprt gene and result in a selectable HPRT- phenotype. Among the deletion mutants, however, only 21% of the spontaneous mutants versus 55% of both the X-radiation- and radon-induced mutants exhibited loss of the entire hprt gene. More X-radiation-induced deletions than radon-induced deletions extended further than 800 bp in the telomeric direction from the hprt gene (six of 17 versus two of 17). The results show that at the human hprt locus of TK-6 cells the predominant kind of mutation indicative of exposure to both high LET alpha-radiation and low LET X-radiation is a large deletion, spanning the entire hemizygous hprt gene and extending into flanking sequences.

Sequencing of double-stranded polymerase chain reaction products for mutation analysis

This report describes a reproducible, straightforward approach to sequencing double-stranded DNA products from the polymerase chain reaction (PCR) for analysis of mutations. The sequencing protocol is a modification of that published by Kretz (Kretz et al., 1989) and has been successful in the hands of a number of investigators working on diverse projects. Following this procedure, PCR DNA products generated from bacterial sources (including pBR322 and F' derivatives), as well as cDNA and genomic DNA from both hamster and human cell lines, have been sequenced with equal success. Close attention to the molar ratio of nucleotides to double-stranded DNA template present during the labeling reaction ensures best results.

[Interceptive activity of epostane in pregnant rats and rhesus monkeys]

A complete interceptive action on pregnancy was shown after ig epostane (Epo) 48 and 96 mg/kg on d 10 of pregnancy in rats. ED50 (95% fiducial limits) of Epo was 20.7 (16.3-26.3) mg/kg. Epo 48 mg/kg ig on d12, 14 and 16 of pregnancy lowered rat plasma progesterone concentrations (P less than 0.05) and plasma corticosterone on d 16 of pregnancy (P less than 0.05). Epo 35 mg/(kg.d) was given ig on d 50-54 of pregnancy in rhesus monkeys. Vaginal bleeding was seen in all of the 6 treated monkeys. Complete expulsions of fetal and placental materials occurred in 5 of the treated monkeys, among which 2 aborted on d 53 and the other 3 on d 54 of pregnancy. Plasma progesterone concentrations of the treated monkeys were lowered on d 52, 53 and 54 of pregnancy (P less than 0.05) and plasma estradiol on d 51, 52, 53, 54 and 55 (P less than 0.05), while there were no significant differences in plasma hydrocortisone. Epo may be a valuable supplement to the existing methods of female contraception.

Effects of forelimb amputation and denervation on protein synthesis in spinal cord ganglia of the newt

Analysis of the effects of forelimb amputation and denervation on [35S]methionine incorporation into the protein of newt brachial plexus nerve ganglia showed that amputation increases the level of protein synthesis about 4-fold as compared with that of control (nonamputated) animals. Denervation without amputation nearly doubles the level of protein synthesis as compared with controls. Analysis of labeled protein by means of two-dimensional gel electrophoresis and radioautogram revealed incorporation patterns that are similar to controls; this observation suggests that amputation affects nerve cells quantitatively rather than qualitatively, in influencing the production of putative neurotrophic agents. A group of basic proteins ranging in Mr from 15,000 to 31,000 are prominently expressed in these radioautograms from experimental ganglia and may be important in promoting forelimb regeneration in the newt.