Proliferation of the hypertrophic chondrocytes of the growth plate after physeal distraction. An experimental study in rabbits

Reports on the effects of physeal distraction on chondrocyte proliferation are controversial, and the biologic mechanism of lengthening is still open. Proliferation of the growth plate chondrocytes was studied after gradual physeal distraction in 12 growing rabbits. Distraction of the distal femoral physis was performed with an external fixation device for three to 14 days. Proliferating cells were labeled with 5-bromo-2'-deoxyuridine one hour before killing the animal, and labeled chondrocytes were localized with a specific monoclonal antibody. Labeled chondrocytes were observed in the hypertrophic zone after distraction of three to seven days, in addition to labeling in the proliferative zone; in the remaining physes, the distribution of labeled cells was normal. Physeal widening occurred in all distracted specimens, and a fracture-separation, usually through the hypertrophic zone, in all but one. The labeled hypertrophic cells were seen on the epiphyseal side of the separation gap, five to 20 cells in each specimen. Although hypertrophic chondrocytes are known to be metabolically active, proliferation of these cells has never been reported before. Hypertrophic chondrocytes seem capable of proliferation under special circumstances.

Effects of distraction and compression on proliferation of growth plate chondrocytes. A study in rabbits

An external fixation device was applied across the distal femoral physis in 30 rabbits, and distraction or compression was performed for 3-21 days; either no operation or a sham-operation was performed on the contralateral side. Proliferating cells were labeled with 5-bromo-2'-deoxyuridine, a thymidine analogue, and subsequently localized in decalcified histologic sections using a specific monoclonal antibody. The height of the proliferative and hypertrophic zones was increased after distraction; additionally, fracture-separation through the hypertrophic zone or at the junction of the physis and metaphysis was seen in 13 of the 15 specimens. Labeled cells were encountered only in the proliferative zone in all specimens except after early distraction, where labeled chondrocytes were seen close to the separation gap in the hypertrophic zone, too. Distraction had no effect on the number of labeled cells. A reduction in the height of the proliferative and hypertrophic zones occurred after compression, and the number of proliferating chondrocytes decreased.

Interrelations between power, force production and energy metabolism in maximal leg work using a modified rowing ergometer

The dependence of power on aerobic and anaerobic energy metabolism and on force production was studied in maximal leg exercise. National and international level male rowers (n = 9) performed four modified (legs-only) rowing ergometer exercises: a progressive test, 2-min (T2), 12-min (T12) and 6-min (T6) all-out tests. In T2, significant correlations were observed between power in T2 (PT2) and oxygen debt (r = 0.83, P < 0.05) and between PT2 and average force production (Fav) during the last 30 s (r = 0.85, P < 0.05). These parameters explained 93% of the variation in PT2. The highest correlations between power in T6 (PT6) and physiological parameters were as follows: maximal oxygen uptake (VO2 max: r = 0.87, P < 0.01), blood bicarbonate concentration before the test ([HCO3-before]: r = 0.85, P < 0.05) and blood lactate concentration on anaerobic threshold (BLaAnT: r = -0.82, P < 0.05). Together, these parameters explained 92% of the variation in PT6. In T12, the total power (PT12) correlated with power of anaerobic threshold (PAnT: r = 0.95, P < 0.001) and with the highest VO2 value in this test (VO2 peak: r = 0.92, P < 0.001). These two parameters explained 96% of the variation in PT12. The decrease of at least one of the force parameters during each test was taken as a sign of fatigue. The decline in force was compensated for by an increase in stroke rate at the end of T6 and T12 (P < 0.01, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperglycemic glucose concentrations up-regulate the expression of type VI collagen in vitro. Relevance to alterations of peripheral nerves in diabetes mellitus

Electron microscopy of peripheral nerves obtained from two diabetic patients revealed large deposits of microfibrils and the presence of Luse bodies in the vicinity of perineurial cells. Microfibrils were found to accumulate also in the sciatic nerves of diabetic BB rats; these microfibrillar deposits were shown to contain type VI collagen by immunoelectron microscopy. Connective tissue cells cultured from rat sciatic nerves were exposed to high glucose concentrations. High glucose concentrations up-regulated the mRNA steady-state levels of alpha 1(VI), alpha 2(VI), and alpha 3(VI) chains of type VI collagen and caused accumulation of type VI collagen-containing fibrils in the cultures. Immunostaining and in situ hybridizations demonstrated that perineurial cells, Schwann cells, and fibroblasts expressed type VI collagen at the mRNA and protein levels. The results suggest that the turnover and supramolecular assembly of type VI collagen are perturbed in diabetic nerves and that glucose per se increases the expression of type VI collagen in vitro.

Basement membranes during development of human nerve: Schwann cells and perineurial cells display marked changes in their expression profiles for laminin subunits and beta 1 and beta 4 integrins

The formation of the connective tissue compartments of human sciatic and tibial nerves was studied with special reference to the maturation of the basement membranes during foetal development (11-35 weeks of gestation). All Schwann cells were surrounded by continuous basement membranes as early as at week 11, while the perineurial cells became covered by basement membranes gradually between weeks 17 and 35, as estimated by electron microscopy. The first laminin subunits detectable within the nerve were the B1, B2 and M chains. These laminin subunits were present in Schwann cell basement membrane zone at week 11, and in the perineurium at week 17 and later. Laminin A and S chains were first detected at 26 weeks in the perineurium, and at a later stage (35 weeks) on Schwann cells. In mature nerves, all these five laminin chains could be demonstrated in both Schwann cell and perineurial cell basement membrane zones, although A, S and B2 chains predominated in the perineurium, and M, B1 and B2 were the predominant chains in Schwann cell basement membranes. Beta 1 and beta 4 integrins were expressed by all Schwann cells in samples from the youngest foetuses (11-17 weeks). At 22-35 weeks, however, only a subpopulation of Schwann cells stained positively for beta 1 and beta 4 integrins. Perineurial cells expressed beta 1 integrins at all ages studied. Staining for beta 4 integrin in perineurium became detectable and intensified concomitant with the formation of structural basement membranes. The results demonstrate that Schwann cells and perineurial cells change their laminin and integrin expression profiles during the maturation of peripheral nerve.

Expression of glucose transporter 1 in adult and developing human peripheral nerve

Northern hybridization of total RNA isolated from adult human sciatic nerve demonstrated a readily detectable hybridization signal for glucose transporter 1 (GLUT 1) mRNA. Western blot analysis demonstrated that GLUT 1 proteins extracted from adult human and from mature rat sciatic nerves had different electrophoretical mobilities. The migration positions of human and rat GLUT 1 proteins corresponded to 60-70 kDa and 55-60 kDa, respectively, as estimated by markers with known molecular masses. Indirect immunofluorescence staining localized GLUT 1 to the perineurium in the adult human sciatic nerve. Only a few endoneurial capillaries of human adult nerve stained positively for GLUT 1, which was in contrast to rat peripheral nerve where most endoneurial capillaries were positive for GLUT 1. In developing human nerves, the staining pattern for GLUT 1 was markedly different from that of the adult nerves: at 14 weeks, the perineurial cells were entirely negative for GLUT 1. Between 22 and 26 weeks of gestation, the staining reaction for GLUT 1 in the perineurium became markedly more prominent, and by 35 weeks the intense perineurial staining resembled that observed in the adult human nerves. In contrast to adult nerves, both endo- and epineurial blood vessels stained intensely for GLUT 1 in the fetal samples. Thus, the immunoreactivity for GLUT 1 in the perineurium seems to increase concomitant with the maturation of barrier properties of perineurium, whereas the transient expression of GLUT 1 in the vasculature of developing nerve may have a specific role in the proliferating endothelial cells.

Expression of laminin isoforms by peripheral nerve-derived connective tissue cells in culture. Comparison with epitope distribution in normal human nerve and neural tumors in vivo

BACKGROUND

Laminins are a family of multifunctional glycoproteins that play a role in various aspects of cell biology. Three different isoforms of laminin have been described, and each comprises a molecule consisting of three subunit polypeptides, the A, B1, B2, M or S chain.

EXPERIMENTAL DESIGN

The expression pattern of laminin isoforms was studied by indirect immunofluorescence staining of human peripheral nerve in situ or cell cultures derived from such nerve by using monoclonal antibodies recognizing the subunit epitopes.

RESULTS

Selective expression of the subunit polypeptides of laminin isoforms in endoneurium and perineurium was demonstrated. Specifically, an intense immunoreaction for A, B2 and S chain epitopes could be detected in perineurium, whereas endoneurium revealed the presence of B1, B2, M and S chains. Examination of the laminin isoform expression in perineurial cells, Schwann cells, and fibroblasts in cultures derived from normal human nerve indicated, however, that these cells under in vitro conditions were capable of expressing all five laminin chains. Cutaneous neurofibromas, tumors characterized by the presence of mixed cell populations consisting of Schwann cells, perineurial cells, and fibroblasts, demonstrated the expression of B1, B2 and M chain epitopes, whereas only a weak immunostaining could be detected with antibodies recognizing the A and S chains. Similar observations were made on schwannomas, a Schwann cell tumor.

CONCLUSIONS

Collectively, the observations of this study attest to the plasticity of neural-derived connective tissue cells with respect to laminin isoform expression. Such plasticity may relate to the cell-cell and cell-matrix interactions during development of peripheral nerves and the potential for neural regeneration.

Glucose transporters of rat peripheral nerve. Differential expression of GLUT1 gene by Schwann cells and perineural cells in vivo and in vitro

Expression of GLUTs in rat peripheral nerve was first studied at the mRNA level with Northern transfer analysis with cDNAs specific for GLUT1, GLUT2, GLUT3, and GLUT4. GLUT1 mRNA was the only GLUT mRNA detectable in rat sciatic nerve. In situ hybridization localized this mRNA to the perineurium and to some endo- and epineurial capillaries. Indirect immunofluorescence stainings demonstrated that GLUT1 protein epitopes were concentrated primarily in the perineurium and endoneurial capillaries. Also, some Schwann cells, a few epineurial capillaries, and medium-sized blood vessels showed a faintly positive immunoreaction. All cell types present in primary cultures initiated from rat sciatic nerve (perineurial cells, Schwann cells, and fibroblasts) expressed GLUT1 protein in vitro. Thus, Schwann cells, which expressed GLUT1 only occasionally at a low level in vivo, have the potential to express GLUT1 at a markedly higher level under cell culture conditions. Incubation of the cultures in 25 mM D-glucose for 7 days caused a 39% reduction in the amount of immunodetectable GLUT1 protein, and a marked (34%) decrease of GLUT1 mRNA compared with cultures incubated in 5.5 mM D-glucose. Interestingly, the reduction of [3H]-2-DG uptake in the same cultures exceeded 70%, suggesting that the reduced amount of GLUT1 protein alone did not explain the marked reduction in glucose uptake in these cultures. Immunostaining of the cell cultures suggested that perineurial cells were the main target for the glucose-induced decrease of GLUT1 protein.

Differential expression of laminin isoforms and beta 4 integrin epitopes in the basement membrane zone of normal human skin and basal cell carcinomas

The basement membrane zone biology of normal human skin and basal cell carcinomas was explored by indirect immunofluorescence with monoclonal antibodies recognizing five subunit polypeptides of three different laminin isoforms as well as the beta 4 integrin epitopes. The laminin antibodies were specific for A, B1, and B2 chains of classic laminin, for the M chain of merosin, or for the S chain in S-laminin. Immunostaining of normal human skin revealed a strong signal with antibodies for A, B1, and B2 chain epitopes. A weak immunosignal was detected with an anti-M chain antibody, whereas the S-chain epitopes were undetectable, even following pretreatment of sections with hyaluronidase. Thus, the laminin at the epidermal-dermal junction of normal human skin is primarily of the classic type, with some merosin molecules being present. The staining of six nodular basal cell carcinomas revealed the presence of A, B1, and B2 chain epitopes in a linear pattern, but, in contrast to normal skin, the antibody recognizing M-chain epitopes yielded a strong immunosignal, and S-chain epitopes could also be readily detected. Staining for beta 4 integrins, potential receptors for laminin, revealed a strong staining reaction in normal skin as well as in the superficial portions of the basal cell carcinoma. However, the immunofluorescence pattern in the deeper portions of the lesions was scattered and interrupted. Thus, altered composition of the basement membrane of nodular basal cell carcinomas with respect to laminin isoforms and their interactions with putative cell-surface receptors, the beta 4 integrins, may change the containment of the tumor islands, contributing to the local aggressive behavior of basal cell carcinomas.

Expression of fibronectin and integrins in cultured periodontal ligament epithelial cells

The process of attachment of epithelial cells obtained from the porcine periodontal ligament (cell rests of Malassez) to different extracellular matrix proteins and their expression of fibronectin and integrin receptors were studied by means of immunocytochemistry, in situ hybridization, and time-lapse cinemicrography techniques. The cell lines of periodontal ligament epithelial cells (PLE cells) attached to and spread rapidly on fibronectin, vitronectin, and type I collagen. One of the cell lines also attached to laminin, while the other cell line showed poor attachment to both laminin and Matrigel, a basement membrane material. By use of the in situ hybridization technique, some PLE cells were found to express the fibronectin gene strongly. Immunocytochemical staining localized fibronectin in extracellular fibrils and intracellular granules. Fibronectin was also found in the tracks left behind by the cells migrating on the substratum. Arg-gly-asp-ser peptide inhibited the attachment of the PLE cells to fibronectin, laminin, type I collagen, and vitronectin by 47%, 43%, 83%, and 94%, respectively, suggesting that the cell-matrix interactions were partly mediated by receptors related to the integrin family. Antibodies against the beta 1-integrin subunit stained the cell bodies and the plasma membrane projections of spreading cells. After 24 h or longer in culture, beta 1-integrins were localized to the regions of cell-cell contact. Cinemicrography of the arg-gly-asp-ser-peptide-treated cells demonstrated that the spreading and migration of isolated cells were prevented by the peptide. The peptide did not appear to dissociate the cell-cell contacts or interfere with migration of spread-cell colonies.(ABSTRACT TRUNCATED AT 250 WORDS)

Distraction osteogenesis of the mandible. An experimental study on sheep

Distraction bone healing has been studied in long bones but there are only few experiments reported in relation to the mandible. The histological pattern of the healing process after mandibular distraction is described. After osteotomy the mandibles of 17 growing sheep were lengthened by gradual distraction using an external fixation device. The follow-up varied from 0 to 52 weeks. The results indicate that bone healing in mandibles is principally the same as in long bones. Four phases can be observed during the repair process: 1) formation of collagen aligned in the direction of distraction, 2) bone formation over the collagen template, 3) bone union across the distraction gap, and 4) remodelling of the lengthened segment. Some increased osteoblast activity was also seen in the control side.

Elevated expression of beta 1 and beta 2 integrins, intercellular adhesion molecule 1, and endothelial leukocyte adhesion molecule 1 in the skin of patients with systemic sclerosis of recent onset

OBJECTIVE

To investigate the possible role of integrins and cell adhesion molecules in the pathogenesis of the mononuclear cell infiltration and fibrosis of skin that occurs in systemic sclerosis (SSc).

METHODS

The presence and topographic distribution of beta 1, beta 2, and beta 4 integrins, as well as of endothelial leukocyte adhesion molecule 1 (ELAM-1) and intercellular adhesion molecule 1 (ICAM-1), was examined immunohistochemically in affected skin from 8 patients with rapidly progressive SSc of recent onset. The expression of the beta 1 integrin gene was also investigated by in situ hybridization with a human sequence-specific complementary DNA.

RESULTS

The presence of beta 1 integrin epitopes and the corresponding messenger RNA within inflammatory cells surrounding small vessels was demonstrated in SSc skin but not in normal skin. Lymphocytes positive for beta 2 integrin were also found only in SSc skin, and they appeared in close proximity to small blood vessels and collagen bundles. Immunostaining for beta 4 integrin epitopes revealed no differences between normal and SSc skin. ELAM-1 and ICAM-1 monoclonal antibodies, which identify epitopes indicative of endothelial cell activation, stained endothelial cells in SSc skin but not normal skin.

CONCLUSION

These observations suggest that the complex interactions of beta 1 and beta 2 integrins, as well as ELAM-1 and ICAM-1, may be intimately involved in the pathogenesis of SSc, perhaps by mediating the homing and targeting of pathogenetic lymphocytes to the affected tissues.

Extracellular matrix gene expression by human endothelial and smooth muscle cells

In this study, the expression of extracellular matrix genes by vascular cells from human iliac blood vessels was characterized on the mRNA steady-state level by slot blot and Northern transfer analyses, as well as by in situ hybridization. Endothelial cells were isolated from adult human iliac arteries and veins, as well as from umbilical veins; smooth muscle cells were isolated from adult human iliac arteries and inferior vena cava. The results show that confluent umbilical vein endothelial cells expressed the genes that encode types I, III, IV and VI collagens, as well as fibronectin and laminin. In contrast, the iliac endothelial cells expressed the genes for types IV and V collagens, fibronectin and laminin; mRNA transcripts for types I, III and VI collagens were not detectable. The smooth muscle cells from iliac arteries or inferior vena cava displayed gene expression for types I, III, IV, V and VI collagens, fibronectin and laminin. The results indicate major differences in gene expression for the various types of collagens by human iliac endothelial and smooth muscle cells. Furthermore, the fetal-derived umbilical endothelial cells displayed differential collagen gene expression from that of adult iliac endothelial cells.

Endothelial cell growth factor and heparin regulate collagen gene expression in keloid fibroblasts

Keloids are benign cutaneous tumours characterized by excess deposition of collagen, specifically type I collagen. We report here that collagen biosynthesis, as measured by hydroxyproline synthesis, was markedly inhibited by 65-80% by the combination of endothelial cell growth factor (ECGF) supplement and heparin in keloid fibroblast cultures. Fibroblast cultures that were incubated with ECGF alone also demonstrated a measurable decrease of approx. 50% in collagen synthesis compared with control cultures. The inhibition of collagen synthesis was related to the down-regulation of collagen gene expression. Quantitative measurements of mRNA-cDNA hybrids revealed that the gene expression of collagen type I was decreased by more than 80% by heparin and ECGF. Markedly diminished levels of mRNA encoding collagen type I were also observed in cultures incubated with ECGF alone. The results show that ECGF and heparin elicit a negative regulatory effect on collagen production, and that this inhibition is due largely to the down-regulation of the pro-alpha 1(I) of type I collagen gene. Furthermore, ECGF has a potent suppressive effect, and heparin provides an additive effect to this inhibitory phenomenon.

Expression of beta 4 integrins in human skin: comparison of epidermal distribution with beta 1-integrin epitopes, and modulation by calcium and vitamin D3 in cultured keratinocytes

The expression of beta 4 integrins in adult and fetal human skin as well as in cultured keratinocytes was studied by immunodetection with monoclonal antibodies, and compared with that of beta 1 integrins. The distribution of the beta 1 and beta 4 integrin epitopes was entirely different in the adult epidermis. As reported previously by us (J Clin Invest 84:1916, 1989), the beta 1 epitopes were present most prominently at lateral cell-cell contact points, whereas staining with the beta 4 antibody demonstrated a linear staining pattern polarizing to the basal surface juxtaposed to the dermal-epidermal basement membrane. In contrast, in fetal skin, the staining patterns both with beta 1 and beta 4 antibodies were similar and demonstrated the presence of epitopes surrounding the entire cell surface of both basal and suprabasal keratinocytes. Distinct polarization of beta 4 integrin epitopes was noted in cultured keratinocytes maintained in low-calcium (0.15 mM) medium, and the expression of these integrins was also noted in human papilloma virus-transformed keratinocytes. Switch of the cultures to high-calcium (1.2 mM) medium resulted in redistribution of the epitopes to a pattern suggesting their location at under-surface of the cells adjacent to the substratum. This Ca(++)-induced redistribution of beta 4 integrin epitopes could be counteracted by 10(-7) M vitamin D3. Finally, incubation with anti-beta 4 integrin antibody reduced the capacity of keratinocytes to attach to plastic substratum. The results provide further evidence for the role of beta 4 integrins in cell-matrix interactions.

Activation of collagen gene expression in keloids: co-localization of type I and VI collagen and transforming growth factor-beta 1 mRNA

Untreated, clinically active keloids were examined as model system to study the spatial expression of extracellular matrix and transforming growth factor-beta 1 (TGF-beta 1) genes in fibrotic skin diseases. In situ hybridizations localized active expression of type I and VI collagen genes to the areas containing an abundance of fibroblasts and apparently representing the expanding border of the lesions. Within this zone, microvascular endothelial cells also expressed the type I collagen genes, as evaluated by simultaneous use of in situ hybridization for collagen gene expression and immunolocalization for factor VIII-related antigen, a marker for endothelial cell differentiation. Slot-blot hybridizations of RNA isolated from this zone suggested that the expression of type I and IV collagen genes was selectively enhanced, as compared to type III collagen gene expression. TGF-beta 1 protein and mRNA were also detected in areas active in type I and type VI collagen gene expression, indicating that TGF-beta 1 gene is transcribed and the corresponding protein is deposited in areas of elevated collagen gene expression, including microvascular endothelial cells. We conclude that the initial step in the development of fibrotic reaction in keloids involves the expression of the TGF-beta 1 gene by the neovascular endothelial cells, thus activating the adjacent fibroblasts to express markedly elevated levels of TGF-beta 1, as well as type I and VI collagen genes.

Presence of type I and VI collagen mRNAs in endothelial cells in cutaneous neurofibromas

In situ hybridization and peroxidase anti-peroxidase immunodetection were used in the same tissue sections to elucidate the spatial distribution of collagen gene expression in cutaneous neurofibromas, particularly in relation to blood vessels; the latter structures were identified by the presence of factor VIII-related antigen. The data indicate a clear relationship between the vascular structures and sites of locally elevated expression of type I and VI collagen genes. Specifically, some, but not all, blood vessels were surrounded by stromal cells highly active in expressing pro alpha 1(I) and alpha 2(VI) collagen genes. Furthermore, these genes were expressed by a subpopulation of endothelial cells within the walls of blood vessels traversing the lesion. To quantitate the overall expression of five genetically distinct collagen genes in cutaneous neurofibromas, we performed Northern analyses and slot blot hybridizations with pro alpha 1 (I), pro alpha 2 (I), pro alpha 1 (III), pro alpha 1 (IV) and alpha 2(VI) collagen cDNAs. Although the mRNA levels for all five genes were slightly increased in neurofibroma tissue, only the abundance of alpha 2(VI) collagen mRNAs was significantly elevated, as compared with normal skin. We conclude that endothelial cell populations with different levels of collagen gene expression exist within cutaneous neurofibromas: some are actively expressing type I and VI collagen genes, whereas in other the expression of these genes is effectively down-regulated. The markedly elevated steady-state levels of type VI collagen mRNAs suggest that synthesis of type VI collagen may contribute to the growth and architecture of cutaneous neurofibromas.

Differential modulation of basement membrane gene expression in human fibrosarcoma HT-1080 cells by transforming growth factor-beta 1. Enhanced type IV collagen and fibronectin gene expression correlates with altered culture phenotype of the cells

The effects of transforming growth factor-beta 1 (TGF-beta 1) on the regulation of basement membrane gene expression were studied in human fibrosarcoma HT-1080 cell cultures. Treatment of cells with TGF-beta 1 resulted in a time- and dose-dependent enhancement of type IV collagen and fibronectin gene expression, as detected both at the mRNA level by Northern hybridizations and at the protein level by semi-quantitative indirect immunofluorescence analyses. These changes were accompanied by profoundly altered morphology of the cell cultures. In contrast, laminin B1 and B2 chain, and nidogen mRNA levels remained unaltered by TGF-beta 1 in the same cultures, indicating uncoordinate modulation of the expression of basement membrane components by TGF-beta 1. Cycloheximide experiments provided evidence that the TGF-beta 1-elicited upregulation of the expression of the fibronectin gene is, but that of type IV collagen is not, entirely dependent on protein synthesis, suggesting two different mechanisms for enhancement of gene expression. Incubation of HT-1080 cells with TGF-beta 1 also resulted in a slightly enhanced expression of beta 1 and alpha 5 integrin mRNAs, as well as beta 1 integrin epitopes. Furthermore, incubation of the cells with anti-beta 1 integrin antibodies partially counteracted the TGF-beta 1-induced morphologic alterations. These studies provide evidence for the role of beta 1 integrins in TGF-beta 1 elicited alterations in HT-1080 cell culture morphology, possibly mediated by the expression of ligand proteins for these integrins, such as type IV collagen and fibronectin.

Increased matrix gene expression by glucose in rat neural connective tissue cells in culture

The effects of different glucose concentrations on the expression of extracellular matrix genes were examined in primary cell cultures initiated from sciatic nerves of nondiabetic Sprague-Dawley rats. The cells were incubated in medium containing 5.5, 15, or 25 mM D-glucose, and the expression of type I and IV collagens, laminin, and fibronectin genes was examined at mRNA steady-state levels by Northern hybridizations. Incubation of cell cultures, consisting of Schwann cells, perineurial cells, and fibroblasts, in high glucose concentrations (15 or 25 mM D-glucose) resulted in elevation of pro-alpha 1(IV), pro-alpha 2(IV), and pro-alpha 1(I) collagen chain and fibronectin mRNAs after only 3 days of incubation, whereas laminin B2 chain mRNA levels appeared unaltered. These observations suggest that hyperglycemia may partially contribute to basement membrane thickening in peripheral nerves of diabetic individuals by increasing the expression of genes coding for basement membrane components, e.g., type IV collagen.

Plasticity of integrin expression by nerve-derived connective tissue cells. Human Schwann cells, perineurial cells, and fibroblasts express markedly different patterns of beta 1 integrins during nerve development, neoplasia, and in vitro

Strikingly selective expression patterns of beta 1, alpha 2, alpha 3, and alpha 5 integrin subunits were revealed in endoneurium, perineurium, and epineurium of fetal and adult human peripheral nerve by immunostaining with specific antibodies. The alpha 2 subunit was expressed only on Schwann cells both in fetal and adult nerve, whereas the alpha 3 epitopes were expressed exclusively in the adult tissue and were primarily present on perineurial cells. The alpha 5 epitopes were expressed only on the innermost cell layer of perineurium of fetal and adult nerve. The tumor cells within schwannomas and cutaneous neurofibromas expressed both alpha 2 and alpha 3 subunits, indicating that Schwann cells have the potential to express also the alpha 3 subunit in vivo. Cell cultures established from human fetal nerve and neurofibromas revealed expression of the alpha 2 and alpha 5 epitopes on Schwann cells, perineurial cells, and fibroblasts, whereas only Schwann cells contained the alpha 3 epitopes which were occasionally concentrated on the adjacent Schwann cells at cell-cell contacts. Our findings emphasize that nerve connective tissue cells change their profiles for expression of extracellular matrix receptors under conditions which have different regulatory control signals exerted by, for example, axons, humoral factors, or the extracellular matrix of the peripheral nerve. This plasticity may play an important role during nerve development and in neoplastic processes affecting the connective tissue compartments of peripheral nerve.

Combined use of in situ hybridization and unlabeled antibody peroxidase anti-peroxidase methods: simultaneous detection of type I procollagen mRNAs and factor VIII-related antigen epitopes in keloid tissue

In this study, we developed methodology that allows the combined use of in situ hybridization and peroxidase anti-peroxidase techniques on the same tissue section. A human pro alpha 1(I) collagen cDNA and antibodies to factor VIII-related antigen were used on keloid tissue sections as a model for a fibrotic reaction. The basic protocols of the techniques were modified to obtain optimal results. The feasibility of this new method was demonstrated by elucidation of type I procollagen gene expression in the cells of blood vessel wall and the adjacent fibroblasts. In the case of capillaries, pro alpha 1(I) collagen mRNAs were detected within endothelial cells identified by the presence of factor VIII-related antigen. Pro alpha 1(I) collagen mRNAs were also found in close proximity of medium-size blood vessels, but in this context clearly outside the vessel wall. These results may contribute to the understanding of pathogenetic aspects of keloids and other fibrotic conditions. Thus, the combination of in situ hybridization and peroxidase anti-peroxidase techniques provides a useful tool to examine gene expression simultaneously both at mRNA and protein levels in fibrotic tissues. This methodology is also applicable to a variety of other biologic and pathologic situations.

Results of elbow synovectomy in rheumatoid arthritis

Synovectomy of the elbow was performed on 54 patients (70 elbows) with rheumatoid arthritis. The mean follow-up time was 7.5 years (range 1.5-22 years). Clinical evaluation showed marked relief of pain in 28 elbows (40%). In 27 cases (38.5%) the pain was moderate but still less than preoperatively. Severe pain was recorded in 15 cases (21.5%) at the time of check up. As to postoperative range of movement, the mean flexion are was 114.5 degrees and the mean rotation are 134.5 degrees. Latitudinal instability was recorded up to 5 degrees in 33 (47%) elbows, up to 10 degrees in 20 (28.5%), up to 15 degrees in 6 (8.5%), and more than 15 degrees in 11 (16%). The mean carrying angle was 10 degrees in valgus. Measurement of strength in flexion and extension showed a reduction of approximately 50% compared to age-matched healthy controls. Reoperations were performed in 10 elbows (14%); the interval between the primary synovectomy and second operation in these cases averaged 8 years.