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H C Bauer

Publications and source records attributed to H C Bauer.

At least 91 records · Page 5Linked to original sources
PubMed1989

Micromethod for the determination of 3-beta-HSD activity in cultured cells.

A modified radioassay for the determination of the 3 beta-hydroxy-delta 5-steroid dehydrogenase (3-beta-HSD) is described. The assay is based on the conversion of [3H]pregnenolone to [3H]progesterone followed by a digitonin precipitation step. The method was applied to neurons, glial cells, C6 glioma cells and adrenal tumor cells in culture. Adrenal tumor cells and C6 glioma cells showed higher enzyme activity than primary cultures of astrocytes and neurons. Dependence of enzyme activity on pH, protein concentration and reaction time was demonstrated for C6 cells. A pH optimum was shown between 7.5 and 8.1, and the reaction was linear up to 2 h. beta-oestradiol inhibited 3-beta-HSD activity completely. The assay presented is fast, highly reproducible, and offers the possibility of studying 3-beta-HSD activity in differentiating cells in culture without preparation of microsomes or extraction of reaction products.

3-Hydroxysteroid Dehydrogenases↗
PubMed1989

Isolation, characterization, and long-term cultivation of porcine and murine cerebral capillary endothelial cells.

We present a simple method for isolation and long-term cultivation of porcine and murine cerebral capillary endothelial cells (cEC). Two major points are made. First, that the "characteristic" morphology of the endothelial cells depends mainly on the presence of endothelial cell growth factors in the culture medium and second, that the identification of the cells as endothelial cells requires a special lectin instead of criteria used for large vessel endothelial cells, such as factor VIII staining or LDL uptake. Pure cerebral capillaries were isolated by means of a series of centrifugation steps; endothelial cells were released by collagenase treatment and cultivated on plastic petri dishes, which proved to be better for cell attachment than collagen or gelatin coating. The microvascular cells were cultivated in either the presence or absence of growth factors. Medium 199 + 10% FCS produced mainly spindle-shaped cells, growing in the "hills and valleys" pattern, which, if not passaged for weeks, showed three dimensional tubular structures. Cells of the "cobblestone" phenotype were promoted in medium 199 + 10% FCS, enriched with endothelial cell growth supplement (ECGS) and heparin (referred to as complete medium). These cells retained their phenotype for months and could be passaged up to 35 times till now. If ECGS and heparin were omitted from these cultures, the cells became elongated and resembled smooth muscle cells. This effect was reversible when the cells were transferred to complete medium. With cEC, cloned by limiting dilution, we noticed this reversal phenomenon as well. We used several markers to characterize the microvascular cells and could show that the lectin of Bandeiraea simplicifolia is a highly reliable marker for endothelial cells and that the monoclonal antibody alpha-sm-1 (anti-smooth muscle cell actin) is excellent for determining smooth muscle cells.

Animals↗
PubMed1989

Effect of human interferon-alpha and interferon-gamma on growth, histology, and DNA content of human osteosarcomas in nude mice.

The antitumor effect of human natural and recombinant interferon-gamma (IFN-gamma) was evaluated in human osteosarcomas grown as xenografts in nude mice. IFN-gamma was given as daily subcutaneous injections, alone or in combination with IFN-alpha. The growth of two out of three tested osteosarcomas was inhibited by 2 x 10(5) IU of natural IFN-gamma. A five times higher dose of recombinant IFN-gamma, as compared with natural (n) IFN-gamma, was needed to obtain growth inhibition of one osteosarcoma. This difference in dose-response could be explained by differences in pharmacokinetics. Hence, subcutaneously administered natural IFN-gamma gave 10 times higher serum levels than obtained with the recombinant type. Combination treatment with IFN-alpha and IFN-gamma induced a potentiation of the antitumor effect in one osteosarcoma. In another osteosarcoma, 2-4 x 10(5) IU of nIFN-gamma did not effect tumor growth and could not potentiate the antitumor effect of 2-4 x 10(5) IU of nIFN-alpha. By using DNA analysis in cell suspension and tissue section, the proportion of aneuploid tumor cells within the xenograft could be estimated. This analysis showed that the antitumor effects of IFN were more pronounced than mere measurement of tumor volume suggested. IFN-inhibited tumors were partly replaced by fibroblasts or bone tissue. In conclusion, at the doses given nIFN-gamma appeared to have similar antitumor effects as IFN-alpha in two osteosarcomas, whereas one was sensitive to only IFN-alpha. Combination IFN treatment induced a potentiation of the antitumor effect in one osteosarcoma but not in another. The differences between the osteosarcomas in obtained antitumor effect of IFN treatment probably reflects individual IFN sensitivity and demonstrates the importance of assessing several tumors of the same neoplastic entity.

Animals↗
PubMed1989

Interferon effects on osteoinduction.

Xenografts of human osteosarcoma growing in athymic mice are inhibited in growth rate by human interferon-alpha (IFN-alpha) treatment. In addition, differentiation of trabecular bone occurs external to the osteosarcomatous tissue and this is entirely dependent on IFN treatment. We have used species-specific anticollagens and antivimentin antibodies to determine the species origins of this trabecular bone. By using immunohistochemical procedures, it was found that this bone is host-derived. These results suggest that IFN provoked the production of a bone-inducing agent by the human osteosarcomas.

Animals↗
PubMed1989

Prognostication including DNA analysis in osteosarcoma.

In a retrospective study of 83 osteosarcoma patients treated by surgery and adjuvant interferon from 1971 to 1986, the clinical course was related to different clinicopathologic features and tumor DNA content. DNA analysis was feasible in 60 cases. Four tumors were diploid and 56 hyperploid. The 7-year survival rate, estimated by life-table analysis, was 0.44 for the whole series. Multivariate analysis disclosed that male sex, proximal tumor location, and histologic Grade IV were independent risk factors--all approximately of equal strength. DNA analysis did not provide prognostic information, except for tumors with extreme abnormality of the DNA content, which was associated with a very poor prognosis. A prognostication model was created, based on the number of risk factors present. The 7-year survival rate for patients with none, one, two, or three risk factors was 0.80, 0.59, 0.42, and 0.13, respectively. The estimated 7-year rate of local recurrence was 0.29: 0.07 after ablative surgery and 0.54 after local surgery. Among patients who were free of metastasis 1 year after diagnosis, local recurrence reduced the 7-year survival rate from 0.86 to 0.48. In high-grade osteosarcoma, conventional clinicopathologic features and local tumor control remain the most important prognostic factors.

Adolescent↗
PubMed1989

Ploidy and morphology in osteosarcoma.

In a cytometric DNA study of high-grade osteosarcoma, the relationship between DNA content and morphology was analyzed. The investigation, based on microspectrophotometry of tissue sections and flow cytometry (FCM), included both primary lesions and recurrences. FCM analysis, applied to a consecutive series of 47 primary osteosarcomas, disclosed that 2 were diploid and 45 were nondiploid, 8 of which were tetraploid. Multiple aneuploid peaks were detected in 13 tumors. Among the nondiploid tumors, there was no clear relationship between the peak DNA value(s) and the histologic subtype (osteoblastic, chondroblastic, fibroblastic) or grade (III-IV). The proliferative activity, as reflected by the percentage of S-phase cells, could be determined in 38 of the 47 tumors analyzed by FCM. The percentage was higher for aneuploid than for tetraploid lesions; however, the distribution of S-phase cells was not related to the histologic subtype or the grade of the tumors. To assess the reliability of a single sample for FCM, the DNA content of biopsy and surgical specimens was compared in 20 tumors; there was complete agreement in all cases with respect to the classification of the lesion as diploid, tetraploid or aneuploid. Analysis by FCM or microspectrophotometry of 12 local recurrences and 16 metastases and the corresponding 19 primary tumors showed that an aneuploid characteristic of the primary lesion was retained during progression of the disease. In 12 tumors analyzed by microspectrophotometry in tissue sections, comparison of chondroblastic and osteoblastic/fibroblastic areas within the same lesion consistently disclosed hyperploidy in both areas.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA, Neoplasm↗
PubMed1988

DNA analysis in the differential diagnosis of osteosarcoma.

The DNA content of osteosarcomas, and of giant cell tumors, osteoblastomas, aneurysmal bone cysts, and fibrous dysplasias was determined by cytophotometry. Of 158 tumors, 141 were histologically noncontroversial, whereas 17 posed diagnostic difficulties. In the noncontroversial group, all 41 benign tumors had a diploid (normal) DNA content. Ninety-two of 96 high-grade osteosarcomas were hyperploid (increased DNA content). The four analyzed low-grade parosteal osteosarcomas were diploid. Among 17 diagnostically controversial cases, nine were primarily diagnosed and treated as benign. Three of these patients, nevertheless, exhibited a malignant clinical course and two had local recurrence. All five proved to have hyperploid tumors. The four nonrecurrent lesions were diploid. Of eight patients primarily evaluated as malignant, one died and two developed local recurrence. These three patients had hyperploid tumors. Among the five nonrecurrent lesions, two were hyperploid and three diploid. In the diagnostically controversial group, recurrence or death was consistently related to hyperploidy. The present study shows that the vast majority of high-grade osteosarcomas are hyperploid. Benign bone tumors, which may be mixed up histologically with osteosarcoma, are diploid. Routine DNA analysis of primary bone tumors, as an adjunct to histopathologic assessment, can be employed to obtain diagnostic confirmation. In cases presenting histopathologic difficulties, ploidy determination may provide decisive diagnostic information.

Adolescent↗
PubMed1988

DNA analysis in the differential diagnosis of osteosarcoma.

The DNA content of osteosarcomas, and of giant cell tumors, osteoblastomas, aneurysmal bone cysts, and fibrous dysplasias was determined by cytophotometry. Out of 158 tumors, 141 were histologically noncontroversial, whereas 17 posed diagnostic difficulties. In the noncontroversial group all 41 benign tumors had a diploid (normal) DNA content. Ninety-two of 96 high-grade osteosarcomas were hyperploid (increased DNA content). The four analyzed low-grade parosteal osteosarcomas were diploid. Among 17 diagnostically controversial cases, nine were primarily diagnosed and treated as benign. Three of these patients, nevertheless, exhibited a malignant clinical course and two had local recurrence. All five proved to have hyperploid tumors. The four nonrecurrent lesions were diploid. Of eight cases primarily evaluated as malignant, one died and two developed local recurrence. These three patients had hyperploid tumors. Among the five nonrecurrent lesions, two were hyperploid and three diploid. Hence, in the diagnostically controversial group, recurrence or death was consistently related to hyperploidy. The current study shows that the vast majority of high-grade osteosarcomas are hyperploid. Benign bone tumors, which may be mixed up histologically with osteosarcoma, are diploid. Routine DNA analysis of primary bone tumors, as an adjunct to histopathologic assessment, can be employed to obtain diagnostic confirmation. In cases presenting histopathologic difficulties, ploidy determination may provide decisive diagnostic information.

Adolescent↗
PubMed1988

Interferon-inhibited human osteosarcoma xenografts induce host bone in nude mice.

The growth of human osteosarcoma xenografts in nude mice can be inhibited by human interferon-alpha (IFN-alpha). Histologic examination of growth-inhibited tumors has revealed mineralization and partial replacement of the tumor by normal bone tissue. We have investigated whether the normal bone tissue was formed by differentiated tumor cells or by induction of host stroma to differentiate into bone tissue. Employing antibodies to both murine and human type I collagen, it was found that the normal bone produced in IFN-inhibited osteosarcomas was host derived. These results suggest that IFN induced the osteosarcoma cells to produce a bone-inductive agent that interacts with the host cells, and leads to the formation of mature normal bone tissue in a heterotopic site.

Animals↗
PubMed1988

DNA cytometry of osteosarcoma.

The relationship between cytochemical features and histomorphology in osteosarcoma, and the clinical significance of DNA content were investigated by microspectrophotometry (MSP) of tissue sections and flow cytophotometry (FCM) of cell suspensions. MSP of tissue sections entails the methodological error of determining the DNA content of sectioned cell nuclei. By analyzing 184 normal mesenchymal cell populations, an upper limit of diploidy (normal DNA content) was deduced. Applying this upper limit for 42 sarcomas, 6 were diploid and 36 hyperploid. Comparative analysis of the same lesions by MSP of imprint preparations and by FCM disclosed complete agreement in ploidy classification (diploid versus hyperploid). Retrospective MSP analysis of bone tumors is often impeded by previous demineralization in acid, which destroys DNA. EDTA as an alternative was found to slightly reduce Feulgen DNA stainability of osteosarcomas, but did not affect tumor ploidy determination. Hence, EDTA offers a means of retaining DNA stainability of bone tumors requiring demineralization. MSP analysis of different histologic areas, and comparative FCM analysis of biopsy and surgical specimens, dislosed that individual osteosarcomas are cytochemically uniform despite morphologic heterogeneity. Hence, a single tumor sample for DNA analysis can be relied upon as representative for the tumor as a whole. In a consecutive series of 83 osteosarcoma patients treated by surgery and adjuvant Interferon, the 7-year survival rate was 0.44. MSP DNA analysis gave no significant prognostic information. Multivariate analysis identified 3 risk factors for tumor related death, i.e., male sex, proximal tumor location, and histologic grade IV. In a prognostication model, the 7-year survival rates, for patients with 0, 1, 2, or 3 risk factors, were 0.80, 0.59, 0.42, and 0.13, respectively. Hence, it is possible to identify subgroups of high grade osteosarcoma patients with different prognosis. In a study of 166 primary bone tumors, the applicability of DNA analysis for differential diagnostic purposes was investigated. The series included high grade osteosarcomas, parosteal osteosarcomas and benign bone tumors, which may be mixed up histologically with osteosarcoma. Out of 166 tumors, 149 (90%) were histologically noncontroversial, whereas 17 (10%) posed diagnostic difficulties. In the diagnostically noncontroversial group, all benign tumors and parosteal osteosarcomas were diploid, whereas 97 of 102 osteosarcomas were hyperploid. Hence, hyperploidy seems to be a characteristic feature of high grade osteosarcoma.(ABSTRACT TRUNCATED AT 400 WORDS)

Bone Neoplasms↗
PubMed1987

DNA flow analysis of soft tissue tumors.

The cellular DNA content of 81 soft tissue tumors was determined by means of flow cytometry and related to conventional histologic classification of the same tumors. Comparison of histologic and cytometric analysis showed that all 23 benign tumors were diploid (normal DNA content), whereas the malignant group included both diploid and aneuploid (abnormal DNA content) lesions. There appeared to be a relationship between tumor grade and ploidy level in that 92% of Grade II, 28% of Grade III, and 11% of Grade IV lesions were diploid. Cell distribution analysis, feasible in 51 cases, disclosed that diploid lesions had a low proportion of S and G2 + M cells and most aneuploid lesions a high proportion, indicating a relationship between ploidy level and proliferative activity. The current study shows that solid mesenchymal tumors may be analyzed by DNA flow cytometry. Regardless of histogenetic type, it appears that benign and low-grade tumors are diploid and high-grade tumors, in general, are aneuploid. As to exceptions, DNA analysis may prove to give information beyond that obtained by subjective histologic interpretation. Thus, adequate follow-up might show that high-grade lesions with a diploid DNA content are associated with a better prognosis than expected from histologic classification.

Aneuploidy↗
PubMed1987

Growth inhibition of human osteosarcomas in nude mice by human interferon-alpha: significance of dose and tumor differentiation.

The sensitivity of 11 human osteosarcoma xenografts in nude mice to human interferon-alpha (IFN-alpha) was studied. Growth inhibition could be demonstrated in all tumors but the necessary IFN-alpha dose ranged from 1 X 10(5)-1 X 10(6) IU/day. IFN-alpha had to be given daily to attain growth arrest and growth resumed after reduction of the IFN-alpha dose. The xenografts could be divided in two groups based on their sensitivity to IFN-alpha: one group of five xenografts that were growth arrested by IFN-alpha, 2 X 10(5) IU/day, and another group of six xenografts in which this dose was insufficient to arrest growth. The proportions of S-phase cells, determined by DNA flow cytometry of untreated control xenografts, were lower in the former group compared to the latter less IFN-alpha sensitive group. Histological examination revealed that in four of the five more IFN-alpha sensitive xenografts, tumor tissue was replaced by normal bone and marrow tissue. This was not seen in the respective control xenografts and not in any of the six less sensitive IFN-alpha treated xenografts. It appears that less proliferative osteosarcoma xenografts are more sensitive to growth inhibition by IFN-alpha. Interestingly the antitumor effect by IFN-alpha on these xenografts was expressed not only by growth arrest but also by tumor differentiation.

Aneuploidy↗
PubMed1987

Feulgen DNA stainability of bone tumors after demineralization.

Microspectrophotometric DNA analysis of archival bone tumor tissue is often impeded by previous acid demineralization, which destroys Feulgen DNA stainability. To find an alternative to acid for prospective DNA studies of bone tumors in tissue sections, Feulgen stainability of fresh osteosarcoma specimens after demineralization in neutral EDTA was investigated. The reliability of DNA analysis of weakly Feulgen-stained sections from archival tissue was also studied. Demineralization of four fresh specimens in EDTA slightly reduced Feulgen DNA stainability compared to nondemineralized preparations but did not affect the determination of ploidy level. Hydrolysis tests of one diploid and one hyperploid osteosarcoma showed that the staining relationship between control and tumor cells was not altered by EDTA pretreatment. For DNA studies of bone tumors requiring demineralization, EDTA offers a means of retaining nuclear Feulgen stainability. In 22 archival osteosarcoma specimens of varying Feulgen stainability, three different upper limits of light transmission (75, 85, and 95%) were applied to test the significance of background disturbances in relation to nuclear stain intensity. The relationship between the median total extinction of the control and tumor cell populations was not significantly affected by altering the upper transmission limit except in four poorly stained lesions. The control cells of these four specimens exhibited a median total extinction less than one-third of the maximum encountered. The results suggest that weakly stained archival specimens can be tested for selecting those appropriate for ploidy determination.

Bone Neoplasms↗
PubMed1987

A comparison of indomethacin and diclofenac in the inhibition of experimental heterotopic new bone formation.

The effect of the two nonsteroidal antiinflammatory drugs Diclofenac and Indomethacin on the formation of heterotropic and orthotopic bone in rats was compared. Experimental heterotopic bone formation was induced by implanting demineralized bone matrix into the abdominal wall of rats. Indomethacin (3 mg/kg), Diclofenac (3, 6 or 12 mg/kg), or saline were given as daily subcutaneous injections. 3H-proline and 45Ca were given 24 h before the animals were killed. The net amount of bone formed by induction after three weeks was decreased by 15% by Indomethacin and Diclofenac in a dose of 3 mg/kg. The higher dose of 6 mg/kg of Diclofenac caused a higher degree of inhibition (30%), while 12 mg/kg produced toxic effects. Orthotopic bone was not affected by treatment with Indomethacin or Diclofenac. Although both drugs inhibit prostaglandin synthesis to a different degree, they exert similar effects on induced heterotopic bone, suggesting that this action is caused by an inhibition of the inflammatory response to trauma.

Animals↗
PubMed1987

Comparison of growth inhibiting effect of natural and recombinant interferon-alpha on human osteosarcomas in nude mice.

Of five tested human osteosarcoma xenografts growing in nude mice, two could be growth-arrested by both natural interferon-alpha (nIFN-alpha) and recombinant IFN-alpha 2c (rIFN-alpha 2c). The other three less sensitive xenografts could only be partly growth-inhibited by the nIFN-alpha while no effect was seen with rIFN-alpha 2c. The leukocyte-derived IFN, thus, appeared to have higher antitumor activity per antiviral unit than the recombinant-produced IFN. It is questionable whether this observed difference is of practical relevance for clinical trials employing different IFN-alpha preparations.

Animals↗
PubMed1987

Methotrexate effects on heterotopic bone in rats.

We studied the effects of high-dose methotrexate on heterotopic bone formation induced by implants of demineralized bone matrix in the abdominal wall of growing rats. Methotrexate induced an arrest in normal weight gain of the animals, more pronounced the younger the animals were. The youngest animals had reduced ash weight and decreased isotope uptake in the tibiae and teeth. However, implants from these animals, given methotrexate 10 days before implantation of bone matrix, had a 33 per cent increase in ash content. When methotrexate was given at, or 10 days after, implantation, heterotopic bone formation was reduced by 40 and 22 per cent, respectively, whereas orthotopic bone was considerably less affected in these older animals. In a second experiment, no difference in elimination rates of 45Ca between methotrexate-treated and control rats in implants, teeth, or tibiae were found. It appears that a less detrimental effect of methotrexate on new bone formation can be expected if the drug is given before, or a substantial period after, surgery requiring bone formation for healing.

Animals↗