The adipocyte component of bone marrow in heterotopic bone induced by demineralized incisor grafts

The relative proportion of adipocytes to hematopoietic elements in the marrow of heterotopicallyinduced bone evaluated 4–42 weeks post implantation of demineralized murine incisors was estimated by histologicalanalysis of hematoxylin-eosin stained tissue sections. Using computerized image analysis of microphotographs,the proportion of nuclear cells vs. adipocytes was ascertained. The percentage of adipocytes in marrowincreases over time. Such an effect, the replacement of myelopoietic marrow by adipogenic (yellow) marrowand the resorption of induced bone, is observed in human osteoporosis. A decline in the non-adipogenic cellcompartments of bone marrow accompanying induced bone begins in the fourth week of induction, graduallyprogresses until the 26th week, and does not change after that. The luminosity, a parameter used in image analysisand proportional to the number of nuclear cells, was 124 ± 3 in hematopoietic femoral bone marrow, andthat of bone marrow of the induced bone was of a similar value (117 ± 8) in the fourth week. An evident declinein luminosity of bone marrow filling the foci of heterotopic bone was observed in samples taken at nine weeks(82 ± 20). This process progressed until the 26th week, reaching a luminosity of 70 ± 21. At the 42nd week, theluminosity remained at the same level (71 ± 27). This indicates that the replacement of hematopoietic bonemarrow of heterotopically induced bone by unilocular adipocytes begins relatively early (the fourth week) and ispersistent.The relative proportion of adipocytes to hematopoietic elements in the marrow of heterotopicallyinduced bone evaluated 4–42 weeks post implantation of demineralized murine incisors was estimated by histologicalanalysis of hematoxylin-eosin stained tissue sections. Using computerized image analysis of microphotographs,the proportion of nuclear cells vs. adipocytes was ascertained. The percentage of adipocytes in marrowincreases over time. Such an effect, the replacement of myelopoietic marrow by adipogenic (yellow) marrowand the resorption of induced bone, is observed in human osteoporosis. A decline in the non-adipogenic cellcompartments of bone marrow accompanying induced bone begins in the fourth week of induction, graduallyprogresses until the 26th week, and does not change after that. The luminosity, a parameter used in image analysisand proportional to the number of nuclear cells, was 124 ± 3 in hematopoietic femoral bone marrow, andthat of bone marrow of the induced bone was of a similar value (117 ± 8) in the fourth week. An evident declinein luminosity of bone marrow filling the foci of heterotopic bone was observed in samples taken at nine weeks(82 ± 20). This process progressed until the 26th week, reaching a luminosity of 70 ± 21. At the 42nd week, theluminosity remained at the same level (71 ± 27). This indicates that the replacement of hematopoietic bonemarrow of heterotopically induced bone by unilocular adipocytes begins relatively early (the fourth week) and ispersistent

Fluvastatin increases tyrosinase synthesis induced by UVB irradiation of B16F10 melanoma cells.

Statins are widely used to lower plasma concentrations of lipids, e.g. cholesterol. One of the main effects of statin treatment is inhibition of hydroxymethyl glutaryl-coenzyme A reductase. The role of fluvastatin, a frequently used statin, was examined in potential modulation of tyrosinase (key enzyme of melanogenesis) synthesis. Levels of tyrosinase mRNA induced by UVB irradiation of B16F10 melanoma cell line were measured by real time PCR. Fluvastatin increases tyrosinase mRNA production induced by UVB irradiation in B16F10 melanoma cell line. Fluvastatin treatment may potentially influence melanin synthesis and protection against UV irradiation

Expression of genes for bone morphogenetic proteins BMP-2, BMP-4 and BMP-6 in various parts of the human skeleton

BACKGROUND: Differences in duration of bone healing in various parts of the human skeleton are common experience for orthopaedic surgeons. The reason for these differences is not obvious and not clear.METHODS: In this paper we decided to measure by the use of real-time RT-PCR technique the level of expression of genes for some isoforms of bone morphogenetic proteins (BMPs), whose role is proven in bone formation, bone induction and bone turnover. Seven bone samples recovered from various parts of skeletons from six cadavers of young healthy men who died in traffic accidents were collected. Activity of genes for BMP-2, -4 and -6 was measured by the use of fluorescent SYBR Green I.RESULTS: It was found that expression of m-RNA for BMP-2 and BMP-4 is higher in trabecular bone in epiphyses of long bones, cranial flat bones and corpus mandibulae then in the compact bone of diaphyses of long bones. In all samples examined the expression of m-RNA for BMP-4 was higher than for BMP-2.CONCLUSION: It was shown that m-RNA for BMP-6 is not expressed in the collected samples at all. It is postulated that differences in the level of activation of genes for BMPs is one of the important factors which determine the differences in duration of bone healing of various parts of the human skeleton.Author has checked copyrightDG 16/11/1

Myśl i polityka: księga pamiątkowa dedykowana profesorowi Jackowi Marii Majchrowskiemu T. 3

Publikacja jubileuszowa z okazji 40-lecia pracy naukowej profesora Jacka Majchrowskieg

Effects of Time of Initial Exposure to MSV Sarcoma on Bone Induction by Dentine Matrix Implants and on Orthotopic Femora

Abstract: HCl-demineralized murine lower incisors were implanted intramuscularly into syngeneic BALB/c mice to induce heterotopic osteogenesis. Implants were exposed at the early, preosteogenic stage (4), or at the later, osteogenic stage (12) to the Moloney sarcoma virus (MSV), which within 3–4 days results in a sarcoma. The yield of bone induction was determined by weight of dry bone mass following NaOH hydrolysis of soft tissues. To verify the effect of this sarcoma on orthotopic local femoral bone, the dry mass of the tumor-exposed femora was measured and compared with the weight of MSV-unexposed contralateral controls. MSV-sarcoma or cells involved with their spontaneous rejection have a stimulatory effect on the periosteal membrane of the tumor-adjacent femoral bones, increasing their dry mass on average by 18%. No stimulatory effect on heterotopic bone induction was observed when the MSV sarcoma grew during the early, preosteogenic stage (4 onward), but when the tooth matrix had been exposed to such tumor at the already boneforming stage, (12 onward), the yield of bone induction was enhanced. Thus, it is postulated that lesions induced by MSV during the early, preosteogenic stage inhibit recruitment of osteoprogenitor cells or degrade Bone Morphogenetic Proteins (BMPs