摘要:

AbstractBackground: Autophagy, while frequently observed in embryonic cells undergoing differentiation and in pathologically altered cells, appears to occur less commonly in normal, fully differentiated cells. Our previous work revealed that the frequency of autophagic activity was rather high in the Leydig cells of rat testes, but the functional significance of autophagy in Leydig cells remains obscure. The purpose of the present study is to investigate the possible role of autophagy in steroid‐secreting cells.Methods: The autophagic activity was investigated in two steroid‐secreting cells, e.g., Leydig cells and adrenocortical fasciculata cells of rats. Cytidine monophosphatase (CMPase) cytochemistry was utilized to show the activity of lysosomal enzymes in autophagosomes. Electron microscopic morphometry was employed to analyze the frequencies of autophgy in the cells of the rats intact or treated with related hormones resulting in a hyper‐ or hypo‐secretion of testosterone and corticosterone.Results: Autophagy took place in normal steroid‐secreting cells with higher frequencies than in many other cells including the tubular cells of kidney and hepatocytes. The large number of autophagosomes or autophagic vacuoles allowed to outline the autophagic process in these cells. The C‐shaped double‐membrane profiles tending to demacate a portion of cytoplasm were referred to as pre‐autophagosomes. So called early autophagosomes were the vacuoles enclosed completely by double delimiting membranes, containing normal‐looking cellular components. The majority of sequestered organelles appeared to be mitochondria and smooth endoplasmic reticulum. The autophagosomes starting digestion were considered as late autophagosomes or autophagic vacuoles, the indications of which were the destruction of their contents or the presence of lysosomal enzymes demonstrated by a positive CMPase reaction. Residual bodies were frequently observed to be exocytosed. The quantitative assay revealed an alteration of autophagic activity in close relation with steroid‐secreting states. The number of autophagosomes was one‐fold higher in hyposecreting Leydig cells after 2 days testosterone administration, and three‐fold higher in hyposecreting adrenocortical fasciculata cells after one dosage of dexamethasone administration. In addition, the autophagosomes showed a four‐fold decrease in hypesecreting Leydig cells stimulated by LRH for 2 days.Conclusions: Considering that most of the autophagocytosed organelles were steroid‐producing apparatus, we may conclude that, by removing part of steroid‐producing organelles, autophagy might play a role in adapting to or even regulating the secretory activity. This hypothesis was strongly supported by the fact that the intensity of autophagy varied in company with the fluctuation of steroid secr

ISSN:0003-276X    

DOI:10.1002/ar.1092420202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBackground: Gebhardt (1905. Arch. Entwickl. Org.,20:187–322) originated the hypothesis that the direction of collagen fibers in bone is a structural response to the type of mechanical load to which the bone is subjected. He proposed that collagen fibers aligned parallel to the loading axis are best suited to withstand tensile strain, whereas fibers oriented perpendicular to the loading axis are best able to resist compressive strain. Research comparing load patterns with fiber alignment in bone have tended to support Gebhardt's hypothesis. The aim of the present study is to further test this hypothesis by assessing the correspondence between the distribution of strain and the distribution of collagen fiber orientation in a bone that is subjected to compound loading (i.e.,bothtension and compression at different phases during the loading cycle). The ovine calcaneum was selected to meet this criterion.Methods: Calcaneum surface strain distributions were obtained from experimental results reported by Lanyon (1973. J. Biomech.6:41–49). Histological sections of the calcaneal shaft were prepared and observed using circularly polorized light (CPL) microscopy to determine the distribution of collagen fiber alignment. The observed alignment pattern was then compared with the predicted pattern based on Gebhardt's hypothesis.Results: Contrary to previous studies, our findings show no clear correspondence between the strain type of greatest magnitude and the direction of collagen fibers. Areas of bone characterized by high compression and low tension showed predominantly longitudinal collagen alignment (contra to Gebhardt).Conclusions: It is argued that even small magnitudes of tension operating on local areas of bone may be sufficient to induced collagen alignment favorable to this type of strain, even when greater magnitudes of compressive strain are acting on the same bone volume. © 1995 Wiley‐Lis

ISSN:0003-276X    

DOI:10.1002/ar.1092420203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBackground: Inbred C57BL made mice express a high incidence of spontaneous osteoarthritis of the knee joint at the age of 18 months. We used this strain of mice to find out the effects of life‐long, moderate running exercise on the health of articular cartilage and the incidence of osteoarthritis.Methods: Male mice (294) were divided into controls and runners. The runners were trained daily between 2 and 18 months of age. The speed was 13.3 m/min and the distance on a flatbelt treadmill was 1,000 m/day. The mice were sacrificed at the ages of 2, 6, 10, 14, and 18 months. The Knee joints were sectioned in frontal direction and the osteoarthritic changes were graded using a conventional light microscope. The reproducibility of the grading method was tested by calculating extended k‐coefficient for the results of six researchers.Results: The incidence of osteoarthritis at the age of 18 months increased from 72% in controls to 88% in runners in the medial tibial condyles (P<0.05), and from 80 to 96% in the lateral tibial condyles (P<0.001). The incidence of the most severe osteoarthritic changes rose from 16% in controls to 38% in runners in the medial tibial condyles, and from 4 to 36% in the lateral tibial condyles.Conclusion: According to our results, the moderate, long‐lasting running exercise accelerates the development of osteoarthritis in the knee joints of C57BL mice. © 1995 Wiley‐L

ISSN:0003-276X    

DOI:10.1002/ar.1092420204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBackground: The nature of the multinucleated giant cells (MNGC) elicited in contact with implantable biomaterials is still indecisive.Method: In Wistar rats the MNGC recruited after the implantation of hydroxyapatite (HA) particles in standardized skull defects were examined morphologically (at both the light and electron microscope levels), enzymatically (tartrate‐resistant acid phosphatase and non‐specific esterase), and after a challenge with salmon calcitonin.Results: The MNGC were of great size and contained abundant mitochondria, vacuoles, and vesicles throughout the cytoplasm; they were either tightly apposed to the HA surface or had long and thin processes penetrating the material. When processed for tartrate‐resistant acid phosphatase, only a few cells were weakly stained. The staining was totally suppressed when samples were pretreated with cyanuric chloride in the MNGC but not in the host osteoclasts. Calcitonin induced the withdrewal of the host osteoclasts from the bone surface while the MNGC remained in contact with the HA material.Conclusion: The MNGC recruited to HA particles did not exhibit the morphologic, enzymatic and functional characteristics of the osteoclasts, and consequently must be regarded as macrophage polykaryons. © 1995 Wiley‐L

ISSN:0003-276X    

DOI:10.1002/ar.1092420205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBackground: The matrix metalloproteinases (MMPs) are a family of closely related enzymes, the principal members being the collagenases, gelatinases, and stromelysins. They are synthesized and secreted by connective tissue cells and are capable of degrading all the components of connective tissue matrices at physiological pH.Methods: Patterns of synthesis and distribution of MMPs and their inhibitor, tissue inhibitor of metalloproteinases‐1 (TIMP‐1), are documented in the craniofacial region at sites of bone formation during both intramembranous (e.g., calvaria, maxilla, and mandible) and endochondral ossification (e.g., cartilaginous cranial base and synchondroses) using indirect immunolocalization.Results: MMPs and TIMP‐1 were detected both as bright intracellular accumulations, indicating active synthesis, and as diffuse matrix‐bound extracellular deposits. Gelatinase‐A had an extensive distribution in osteogenic tissues and was detected both in cells of the periosteum and spongiosum and as extracellular deposits in the osteoid layer of newly formed bone. In addition, gelatinase‐AB synthesis was detected in osteoclasts. All regions of the early cartilaginous cranial base produced MMPs and TIMP‐1 were also documented in early tooth germs and in Meckel's cartilage.Conclusions: These data document a prominent role for MMPs, and in particular gelatinase‐A, in mediating matrix degradation during osteogenesis. Their detection in tooth germs and Meckel's cartilage further indicates a role for MMPs and TIMP‐1 in matrix turnover during morphogenesis. © 19

ISSN:0003-276X    

DOI:10.1002/ar.1092420206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBackground: The ability of skeletal muscle to regenerate after injury is well established. In contrast, cardiac muscle is incapable of regeneration and recovery after injury. The aim of the present study was to evaluate and compare the regeneration pattern of cardiac and skeletal muscle after transplantation into a skeletal muscle bed in rats.Methods: The following group of transplants were performed at the site prepared by removing the host extensor digitorum longus (EDL) muscle. The first group consisted of cardiac muscle transplanted as one piece or after mincing into 1‐mm pieces. The second group included cotransplants of cardiac and skeletal muscle minces that were intermixed. Entire EDL muscle or minced EDL muscle were also transplanted for comparison. Rats were sacrificed 3–30 days after transplantation for morphological analysis.Results: The results demonstrated that skeletal muscle transplants underwent rapid regeneration, and by 30 days the entire muscle was filled with regenerated myofibers. In transplants of cardiac muscle significant inflammation, myocardial degeneration and necrosis were observed. In spite of the necrosis and fibrosis, the presence of a few regenerated myotubes in the outer region was observed. In cardiac and skeletal muscle cotransplants, the inflammation was restricted to cardiac tissue; however, by 30 days the entire contransplant was filled with regenerated myotubes and myofibers.Conclusions: These results show that skeletal muscle is capable of growth, regeneration, and integration with the cardiac muscle after cotransplantation. Combination of skeletal and cardiac muscle may prove useful in defining the cellular processes necessary for enhancing cardiac repair after injury. © 1995 Wiley‐Lis

ISSN:0003-276X    

DOI:10.1002/ar.1092420207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBackground: XX/XY chimeric pigs are uncommon and their reproductive anatomy is variable and unpredictable.Method: A piglet was identified by its enlarged vulva as a possible intersex. Venous blood was collected at 1.5 and 9 months for karyotyping and determination of testosterone and estrone sulphate concentrations. At 1 year euthanasia was performed. The reproductive tract was carefully dissected and examined histologically.Results: As the animal matured the vulva did not develop relative to the size of the animal. Lymphocyte cultures indicated a 70% XX/30% XY chimera. The reproductive tract consisted of a strand of tissue enveloped by fascia. Histological study revealed presumptive Wolffian derivatives, coiled bilateral ducts along the tract, and a Müllerian derivative, a medially located duct in the caudal third of the tract. No gonads were found. Plasma levels of estrone sulfate and testosterone were negligible.Conclusions: In utero exposure to exogenous androgens from a male cotwin or weak endogenous adrenal androgens may account for the enlarged vulva at birth and retention of the androgen dependent Wolffian duct primordia. An atesticular state is supported by retention of the Müllerian duct primordia and the negligible peripheral sex steroids. © 1995 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092420208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractGlucocorticoids and sex‐steroids can modulate osteogenesis in vivo and in vitro. Although the effects of glucocorticoids on bone cells in vitro have been described in detail, the role of sex‐steroids is not as well defined. We examined whether sex‐steroids influence bone metabolism indirectly by regulating glucocorticoid effects on bone. Interactions of the sex‐steroid progesterone or its analog RU38486 with the glucocorticoid dexamethasone (dex) were studied in functional assays of osteogenesis. Three osteoblastic models were evaluated:(1) the rat bone marrow stromal cell (RBMC) nodule system; (2) the chick periosteal osteogenesis (CPO) model; and (3) ROS 17/2.8 cells. RU38486, progesterone, and unlabelled dex competitively inhibited3H‐dex uptake by ROS 17/2.8 cells as well as its (3H‐dex) binding to cytosol preps.Both RU38486 and progesterone inhibited dex‐induced increases in alkaline phosphatase in CPO cultures, in RBMC cultures, and in ROS 17/2.8 cells. Dex‐induced decreases in cell proliferation in ROS 17/2.8 cells were reversed by RU38486 but dex‐induced increases in proliferation in the CPO model were not affected. In CPO cultures, dex‐induced increases in collagen synthesis were inhibited completely by RU38486 and progesterone, Dex‐dependent nodule formation in the RBMC was blocked by RU38486. Both RU38486 and dex mediated reduction of calcium uptake in the CPO model but did not affect mineralized tissue area.The data indicate that RU38486 and progesterone competitively inhibit dex‐mediated stimulation of osteogenesis in vitro; this inhibition is exerted on early but not late stage differentiation events of osteoprogenitor cells.

ISSN:0003-276X    

DOI:10.1002/ar.1092420209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractGalectin‐3 is an endogenous soluble lectin within the family called galectins that bind β‐galactosides. Homologs of the protein isolated from different sources were previously designated as IgE‐binding protein (ϵBP), CBP35, CPB30, Mac‐2, RL‐29, RLL, L‐29, and HL‐29. All are now renamed galectin‐3. This lectin is widely distributed in cells and tissues of mice, rats, dogs, hamsters, and humans.Light microscopic immunohistochemistry and ultrastructural immunogold labeling methods were used to determine the distribution of galectin‐3 in human mast cells of several organs, in mast cells developed in vitro from human fetal liver cells, and in human peripheral blood basophils. Immunolabeling for the protein was observed in mast cells from all sources and in basophils. The lectin was detected in the nucleus and/or the cytoplasm. The nuclear labeling was over heterochromatin whereas euchromatin was unlabeled. Cytoplasmic labeling was concentrated over secretory granules. The intensity of staining generally was greater in mast cells of skin when compared with that of mast cells in other locations and with that of basophils. Studies have indicated that in mast cells galectin‐3 may be involved in promoting their adhesion to basal laminae. In this study the localization of galectin‐3 in the secretory granules of human mast cells and basophils suggests that these cells may release this lectin when activated to degranulate.

ISSN:0003-276X    

DOI:10.1002/ar.1092420210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractBackground: There is a need to identify the follicular dendritic cells (FDC) of the chicken spleen at the ultrastructural level during a secondary immune response.Methods: The cells were identified after intravenous priming BSA and boosting with biotinylated BSA conjugated to colloidal gold particles. Monoclonal antibodies raised specifically either to chicken IgG or IgM were used to characterize these immune complex‐trapping cells.Results: The FDC had an irregular morphology which varied through time, supporting the existence of two types of FDC in the chicken spleen, one showing filiform cell processes, the other provided with beaded dendrites. When the filiform dendrites were observed, the FDC bound the antigen on their surfaces. These dendrites showed an intrincate convoluted configuration, forming tightly wrapped networks near the cell body. The networks had the same features as those described in mammals as antigen retaining reticulum (ARR). In chickens, the ARR, which represents sites of antigen localization on FDC, reached maximum development on day 5 after the second injection of BSA and had disappeared by day 8. At this time FDC had beaded dendrites.Conclusions: Antigen is retained on FDC in the chicken spleen for long periods of time. © 1995 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092420211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY