The use of confluence stages does not decrease the overall variability in primary human osteoblasts but can give additional information on differentiation in vitro

Primary cultures of human osteoblast-like cells are frequently used to study osteoblast function. Due to inhomogeneous growth of primary osteoblasts in culture, it is of interest if the use of confluence stages for analysis would reduce the overall variability. Consequently, we have tested the influence of degree of confluence and passage number on the growth and differentiation of human primary osteoblast-like cells. Phenotypic features of primary human osteoblast-like cells were compared at four successive cell densities defined as stage of confluence I (50%), stage II (75%), stage III (100%) and stage IV (5 days post confluence). The stability of the system was also tested by comparing these observations obtained using cells from the 2nd and 4th passages. As a sign for further differentiation, the number of AP-positive cells increased with a decrease in proliferation. The secretion of procollagen-I decreased to 50% during culture while procollagen I mRNA doubled from proliferation to confluence. A constant activity of alkaline phosphatase, procollagen-I secretion and procollagen I gene expression over passages was seen together with a decrease in growth. The paper introduces a potential model of osteoblastic differentiation in vitro for human primary osteoblast-like cells. We were able to show an increasing differentiation with a decrease in proliferation and the stability of this differentiation behaviour over cell passages in this model, but we were not able to reduce the overall variability.

In vitro differentiation potential of a new human osteosarcoma cell line (HOS 58)

Cultured rodent osteoblastic cells reiterate the phenotypic maturation of osteoblasts seen in vivo. Under appropriate culture conditions this maturation is a stepwise sequence of phenotypic changes culminating in the production of a mineralised matrix. Although individual components of the osteoblast phenotype are apparent in transformed osteosarcoma cell lines, the co-ordination of the maturation sequence appears to be compromised. Because to date no comparable human cell differentiation system has been developed we investigated the recently introduced HOS 58 osteosarcoma cell line up to 3 months in culture. Proliferation, the secretion of osteoblast specific proteins, gene expression and mineralisation were analysed at different time points. Low-density HOS 58 cultures exhibit rapid proliferation and high levels of c-myc, collagen type I and osteopontin mRNAs. This phenotypic stage was maximum between the 4th and 5th days of culture. As cell density increased expression of these genes declined and by day 14 the predominant mRNAs was alkaline phosphatase. Osteocalcin secretion was detected after confluence at an increasing level. In the presence of ascorbate and beta-glycerophosphate the production of alkaline phosphatase and collagen type I increased coincident with the elaboration of a Von Kossa staining matrix. Nevertheless no proper mineralisation of the collagenous matrix was detectable by electron microscopy. Hence, the human osteosarcoma cell line HOS 58 expressed a rather differentiated phenotype with further maturation during a culture period of 21 days. We conclude that the developmental sequence exhibited by the HOS 58 human osteosarcoma cell line is comparable to that described for primary rat osteoblasts. However, in detailed analysis considerable differences to other species are evident. Further evaluation of the HOS 58 system and comparison to other human osteoblast cell lines will be necessary to establish the most appropriate differentiation model for human bone cell cultures.

Analysis of human primary bone cells by fluorescence activated cell scanning: methodological problems and preliminary results

We describe the development of flowcytometrical methods to analyse human primary osteoblast-like cultures obtained from trabecular bone explants in comparison to the human osteosarcoma cell line HOS 58. Two antigens typical of osteoblasts were studied: bone alkaline phosphatase and collagen/procollagen I; the non-specific attachment protein fibronectin served as control. The morphology of all different antigens is shown by immunocytochemistry before flowcytometrical analysis. The establishment of flowcytometry is described in detail. While all antigens tested were nearly 100% positive in the HOS 58 cells in immunocytochemistry and flowcytometry, in primary osteoblast-like cells results varied widely between both methods. Cell permeabilisation before flowcytometry improved the homogeneity of results, probably by increasing the accessibility of the specific antibody to intracellular compartments. Though up to 80% of cells were lost during preparation the ratio of positive versus negative cells in specific experiment was not dependent on the cell recovery. Therefore, the cells finally analysed seemed to be representative of the total population.

The human analog of murine cystein rich protein 61 [correction of 16] is a 1alpha,25-dihydroxyvitamin D3 responsive immediate early gene in human fetal osteoblasts: regulation by cytokines, growth factors, and serum

1Alpha,25-dihydroxyvitamin D3 (1,25-(OH)2D3) is a potent mediator of differentiation and maintenance of specific functions of osteoblasts. To detect novel targets for 1,25-(OH)2D3 action, we applied differential display PCR to human fetal osteoblast-like cells and identified the human analog of murine cystein rich protein 61 (hCYR61) as a 1,25-(OH)2D3-responsive immediate early gene in differentiated fetal osteoblast-like cells. The murine gene CYR61 is important for cell-cell and cell-matrix interactions, and it belongs to an emerging gene family of cysteine-rich proteins. hCYR61 messenger RNA (mRNA) steady-state levels were stimulated 11-fold by 10 nM 1,25-(OH)2D3 by 1 h and declined to control levels by 4 h. This transient stimulation of hCYR61 mRNA was not inhibited by cycloheximide but was prevented by actinomycin D, indicating that the 1,25-(OH)2D3 effect involves transcriptional events and does not require de novo protein synthesis. hCYR61 mRNA stability was not influenced by 1,25(OH)2D3, whereas cycloheximide treatment stabilized hCYR61 mRNA. FCS, as well as growth factors and cytokines such as basic fibroblast growth factor, epidermal growth factor, tumor necrosis factor alpha, and interleukin-1, strongly elevated hCYR61 mRNA steady-state levels within 1 h. hCYR61 mRNA was expressed also in primary human osteoblasts and osteosarcoma cell lines. Using a commercial tissue blot, hCYR61 mRNA was only observed in skeletal muscle. The fast and transient response of hCYR 61 to 1,25-(OH)2D3, serum, growth factors, and cytokines suggests an important role of hCYR61 for osteoblast function and differentiation.

[Neonatal Basedow's disease in twins from a mother with severe T3 hyperthyroidism]

HISTORY AND CLINICAL FINDINGS

Dizygotic twin sisters were born to a woman who, shortly before becoming pregnant, had developed Graves' disease with markedly elevated triiodothyronine (T3) levels and highly positive TSH receptor antibody titres (TRAb: 169 mU/ml). From the second week of life onwards they had a goitre and hyperexcitability, tachycardia and failure to thrive were noted. In addition, twin I had mild exophthalmos. As thyrostatic treatment of the mother was very difficult, intrauterine hypothyroidism or transitory hyperthyroidism had presumably occurred in the twins.

INVESTIGATIONS

Twin I had maximal thyroxine (T4) concentration of 26.2 micrograms/dl, while it was 24.7 micrograms/dl in twin II with suppressed TSH. Both twins had high concentrations of TRAb and antibodies against thyroid peroxidase.

DIAGNOSIS, TREATMENT AND COURSE

With the diagnosis of neonatal Graves' disease established, both twins were treated with propranolol (2 mg/kg.d) and phenobarbitone (2-4 mg/kg.d). Twin I, whose symptoms were more severe, also received propylthiouracil (5 mg/kg.d) until euthyroidism had been achieved. Although twin II became euthyroid spontaneously, she gained weight only slowly and microcephaly developed together with definite motor and mental retardation. It remains unclear whether these were consequences of intrauterine hypothyroidism or post-partum hyperthyroidism.

CONCLUSION

Graves' disease during pregnancy demands interdisciplinary collaboration between gynaecologist, physician and paediatrician to prevent severe sequelae in the children. Early risk assessment is possible by measuring the TSH receptor antibody titre in umbilical blood.

Local estradiol metabolism in osteoblast- and osteoclast-like cells

Bone is an estradiol-responsive tissue. Estrogen withdrawal during the menopause causes loss of bone mass and clinically relevant osteoporosis in a third of all women. Sufficient or impaired local production, as well as degradation of estradiol in cells present in the bone microenvironment might be an important mechanism of rescue or might contribute to the development of osteoporosis, respectively. We therefore investigated aromatase and 17beta-hydroxysteroid dehydrogenase type IV (17beta-HSD IV) expression in osteoblast- and osteoclast-like cells. Aromatase mRNA was increasingly expressed in myeloid THP 1 cells differentiated along the monocyte/phagocyte pathway exploiting vitamin D and either granulocyte-macrophage-stimulating factor (GMCSF) or macrophage-stimulating factor (MCSF). In long-term cultures, when sequentially exposed to vitamin D (days 0-21) and GMCSF (days 5-10) and plated on collagen, the amount of expression of aromatase mRNA steadily increased along with the increasing expression of osteopontin mRNA, alpha(v) integrin mRNA, c-fms (MCSF-receptor) mRNA and multinucleated cells developing. The conversion of estradiol from testosterone (10(-7) M/l) in the supernatants of dishes mirrored changes in aromatase mRNA expression and by day 21 rose to 30,000 ng/10(7) cells/24 h. 17Beta-HSD IV mRNA expression was abundant in undifferentiated THP 1 cells and was decreased to approximately 50% by day 21. Unstimulated SV-40 immortalized fetal osteoblasts did not express aromatase mRNA, but the expression was stimulated by the addition of the phorbol ester phorbol myristate acetate (PMA). Unstimulated osteoblasts from primary cultures did not express aromatase mRNA. Osteoblast-like osteosarcoma cells MG 63 expressed faint levels of aromatase mRNA in contrast to the osteosarcoma cell line HOS 58. 17Beta-HSD IV mRNA was expressed in fetal osteoblasts as well as in osteoblasts from primary culture, MG 63 and HOS 58 cells. In summary, we can show the expression of estradiol metabolizing enzymes in cells which are present in the bone microenvironment. Impaired aromatase expression and/or enhanced expression of 17beta-HSD IV may contribute to the pathogenesis of osteoporosis.

Prophylactic application of thyrostatic drugs during excessive iodine exposure in euthyroid patients with thyroid autonomy: a randomized study

In a prospective, randomized study we examined the influence of prophylactic short-term thyrostatic therapy on thyroid iodine metabolism in patients with euthyroid autonomy undergoing elective coronary angiography. From a total of 1177 patients, 51 fulfilled the criteria of euthyroid autonomy before coronary angiography (negative thyrotropin-releasing hormone test, 10-min uptake of at least 1.2%, 99mTc and no elevation of free thyroxine and free triiodothyronine indices) and were randomized into three groups: group 1 (N = 17) received 20mg/day of thiamazole and group 2 (N = 17) received 900 mg/day of sodium perchlorate; thyrostatic therapy was begun on the day before angiography and continued for 14 days; group 3 (N = 17) served as controls without treatment. Parameters of thyroid function-free thyroxine (FT4) index and free triiodothyronine (FT3) index, thyrotropin (TSH) and delta-TSH urine iodine excretion and 99mTc uptake were determined before and 30 days after coronary angiography. At the end of the study the mean FT4 index and FT3 index were elevated significantly in the control group compared with baseline values, but were still within the normal range. In contrast, the mean FT4 index and FT3 index remained unchanged in the treated groups. Four mild cases of hyperthyroidism were observed at the end of the study: two cases in the control group and one case in each of the treated groups. Thyrotropin suppression, urine iodine excretion and 99mTc uptake differed significantly between the treated groups and the control group. In the treated groups TSH suppression, urine iodine excretion and 99mTC uptake remained unchanged 30 days after coronary angiography compared with baseline values. In the control group the degree of TSH suppression and the level of urine iodine excretion increased (about twofold) significantly after coronary angiography, whereas 99mTc uptake decreased significantly (ca. 50%). In conclusion, short-term prophylactic thyrostatic therapy seems to have a protective effect against iodine excess in patients with euthyroid autonomy. However, mild hyperthyroidism could not be prevented in some cases. Probably a combination therapy of thiamazole and perchlorate would be more effective.

The iron-binding protein ferritin is expressed in cells of the osteoblastic lineage in vitro and in vivo

Ferritin, a metal-binding protein responsible for maintaining the bioavailability of iron, has been demonstrated in cells of the osteoblastic lineage. Messenger RNAs encoding the light and heavy chain subunits of ferritin were detected in ROS 17/2.8, ROS 25/1, and UMR106 rat osteosarcoma cell lines, in fetal rat calvaria, and in primary cultures of rat calvarial osteoblast-like cells. In vivo, the expression of ferritin light-chain mRNA was observed in both active osteoblasts and in osteocytes. A 450-kD iron-binding protein was immunoprecipitated from ROS 17/2.8 cells by an antiferritin antiserum. This protein comigrated with native ferritin, and could be dissociated into subunits comigrating with ferritin light and heavy chains. Addition of extracellular Fe59-transferrin to cultures of ROS 17/2.8 cells resulted in the sequestration of the iron in intracellular ferritin. These observations demonstrate that cells of the osteoblastic lineage possess a functional ferritin-based iron uptake and storage system capable of regulating metal homeostasis in bone.

[Aspects of myocardial infarction treatment in patients of higher age (author's transl)]

The influence of a 6 weekly physical training of the performance in patients of the age between 60 and 70 years who have had a definitive myocardial infarction has been tested in phase II or rehability. Dayly in patient and under physicinal control the conditioning were executed in the time of 30 minutes on a bicycle--hometrainer. The personal intensity of training was choosed so that anwunted to 60--70% of heart-frequency obtained by the maximal exercise. Additional a terrain-training was taken part. Under conditioning a different relation of performance was recognized by patients (12 patients--performance decreased, 15 patients--constant performance, 33 patients--performance increased). To prevent a negative development of physical performance the result of performance--pulse (N/Hf) should be observe especially.