High serum levels of YKL-40 in patients with systemic sclerosis are associated with pulmonary involvement

OBJECTIVES

YKL-40, a growth factor of connective tissue cells, is elevated in sera from patients with diseases characterized by inflammation, tissue remodelling, or fibrosis. The aim of the study was to determine serum YKL-40 levels in patients with systemic sclerosis (SSc) and to explore any possible clinical and prognostic associations.

METHODS

YKL-40 was measured in sera from 88 patients with SSc (26 with diffuse and 62 with limited skin involvement) and in sera from 88 matched healthy controls. Immunohistochemical staining for YKL-40 antigen was performed in a biopsy from a patient with pulmonary SSc.

RESULTS

Serum YKL-40 levels of the SSc patients were significantly higher than those of the controls (p<0.00001). Patients with pulmonary fibrosis by chest X-ray, obstructive ventilatory pattern, reduced diffusing capacity (DLco), and digital joint deformity due to skin retraction had significantly higher serum YKL-40 compared with patients without these findings. Patients with elevated serum YKL-40 had shorter survival times than patients with normal serum YKL-40 (p = 0.0005), although this was not independent of age and pulmonary function. YKL-40 protein expression was found in inflammatory cells in fibrosing pulmonary tissue from a patient with SSc.

CONCLUSIONS

Serum YKL-40 is elevated in patients with SSc with pulmonary involvement.

Histochemical studies of the masseter, the temporal and small zygomaticomandibular, and the temporomandibular masticatory muscles from aged male and female humans. Fiber types and myosin isoforms

The purpose of this study was to investigate the histology of two small masticatory muscles from females and males of more than 70 years of age. By using immuno- and enzyme histochemistry the muscles were characterized by their fiber types and myosin heavy chain pattern. The observations were compared with similar studies of the masseter and temporalis muscles. Previously the two small muscles have been described based solely upon their gross anatomy. One muscle originates from the anterior, deep surface of the temporal fascia and inserts in the temporal tendon: the temporo-mandibular muscle (TM). The other muscle originates from the upper part of the temporal surface of the frontal process of the zygomatic bone and the adjacent part of the frontal bone and inserts in the temporal tendon: the zygomaticomandibular muscle (ZM). In the masseter, TM, and ZM, most of the autopsy samples contained an abundant number of fibers containing neonatal myosin heavy chains while in the temporal muscle specimens, such fibers were sparse and scattered. Electrophoresis followed by immuno-staining of Western blots supported the histochemical findings. There was no obvious correspondence between fiber typing based upon ATPase activity and the neonatal myosin heavy chain content in the muscle fibers. Neither did the fibers show accordance in their content of adult slow and fast myosin heavy chains and in their content of neonatal myosin heavy chain.

Serum YKL-40 is increased in patients with hepatic fibrosis

BACKGROUND/AIMS

YKL-40, a mammalian member of the chitinase family, is a lectin that binds heparin and chitin. The function of YKL-40 is unknown, but it may function in tissue remodelling. The aims of this study were to assess the level of circulating YKL-40 in patients with various kinds and degree of chronic liver disease and its possible relation to liver fibrosis.

METHODS

Serum YKL-40 levels were determined by radioimmunoassay in 129 patients with suspected liver disease and related to histological findings and immunohistochemical staining of YKL-40 in a liver biopsy taken simultaneously with the blood sample.

RESULTS

The median serum YKL-40 was highest in patients with alcoholic cirrhosis (532 microg/l), in particular in patients with additional alcoholic hepatitis (740 microg/l). Patients with alcoholic cirrhosis, post-hepatitic cirrhosis (425 microg/l) and non-cirrhotic fibrosis (330 microg/l) had significantly higher serum YKL-40 than normal subjects (102 microg/l), patients with fatty liver (195 microg/l) or patients with viral hepatitis without fibrosis (174 microg/l). Serum YKL-40 was significantly (p<0.001) related to the degree of liver fibrosis with the highest levels in patients with moderate (466 microg/l) to severe (676 microg/l) fibrosis. Serum YKL-40 was also increased (p=0.018) in patients with slight fibrosis (270 microg/l) compared to patients without fibrosis. Immunohistochemical analysis demonstrated positive staining for YKL-40 antigen in areas with fibrosis, particularly areas with active fibrogenesis. YKL-40 staining was never found in hepatocytes.

CONCLUSIONS

Our study indicates that the increased serum YKL-40 in patients with liver disease of various degree and aetiology seems to reflect fibrosis and fibrogenesis.

YKL-40 in giant cells and macrophages from patients with giant cell arteritis

OBJECTIVE

YKL-40, a mammalian member of the family 18 glycosyl hydrolases, is secreted by activated macrophages at a late stage of differentiation. Macrophages are present in inflammation of the arterial wall and are thought to participate in the pathogenesis of giant cell arteritis (GCA). The aim of this study was to evaluate whether macrophages and giant cells of patients with GCA produce YKL-40, and whether serum YKL-40 concentrations are elevated in these patients.

METHODS

Serum YKL-40 was determined by radioimmunoassay in 19 patients with GCA and 8 patients with polymyalgia rheumatica (PMR) who were followed up prospectively during 1 year of treatment with prednisolone. Immunohistochemical staining for YKL-40 was performed in temporal artery biopsy samples that were obtained before treatment.

RESULTS

In the arteritic vessels of patients with GCA, positive staining for the YKL-40 antigen was found in CD68+ giant cells and mononuclear cells located in the media. Macrophages located in the adventitia and intima were negative for YKL-40. At the time of diagnosis, patients with GCA had an increased median serum level of YKL-40 (256 microg/liter; P<0.01) compared with healthy age-matched controls (median 118 microg/liter), and the serum level of YKL-40 decreased to normal levels during prednisolone treatment (-38% after 1 month; P<0.001). Most patients with PMR had normal serum YKL-40 levels (median 158 microg/liter) and had no changes in the serum YKL-40 levels during prednisolone treatment. The observed changes in serum YKL-40 did not always parallel the changes in serum C-reactive protein levels and erythrocyte sedimentation rate during the 1-year study period.

CONCLUSION

YKL-40 is found in CD68+ giant cells and mononuclear cells in the media of arteritic vessels of patients with GCA, and the concentration of serum YKL-40 may reflect the local activity of these cells in the inflamed artery.

Aging affects different human muscles in various ways. An image analysis of the histomorphometric characteristics of fiber types in human masseter and vastus lateralis muscles from young adults and the very old

This study is an attempt to objectively evaluate age-related changes in human muscles by use of histomorphometric methods. Aging in humans induces dramatic transformations in the skeletal muscles but little is known as to whether or not the aging processes per se may affect all muscles equally. In this study aging of two human muscles with different functions, origin and nerve supply is compared. Sections were cut from masseter and vastus lateralis muscles obtained from young adults aged 18-24 years and from the very old aged 90-102 years. Muscle fiber types were classified with the traditional myofibrillar ATPase staining. Various histomorphometric parameters of the different fiber types in human masseter and vastus lateralis muscle sections were obtained by image analyses to evaluate the age-related changes in the muscle fibers. The following variables were calculated: the number of each fiber type per photographed area; the area of each fiber and two indicators for the shape of the muscle fibers. In the aging muscles there was no relative preferential loss of a fiber type. High numbers of intermediate ATPase-stained fibers (IM fibers) were found in some old vastus muscles but were only sporadic in young vastus muscles. However, there was no change in the percentage distribution of intermediate ATPase-stained fibers when young and very old human masseter muscles were compared. Incubation of the sections with antimyosin antibodies showed that the IM fibers in old masseter and old vastus contained different myosin heavy chains. Thus ATPase activity and anti-myosin staining displayed a somewhat different pattern of fiber type distribution. The main changes in the shape and area indicated that type I fibers in the masseter became more circular while in the vastus they decreased significantly in size. The type II fibers in the vastus became very small and deviated significantly from circularity whereas the type II fibers in the masseter only exhibited a decrease in the size of the fibers. Histomorphometric measurements show that aging affects different human muscles in various ways.

YKL-40 in giant cells and macrophages from patients with giant cell arteritis

OBJECTIVE

YKL-40, a mammalian member of the family 18 glycosyl hydrolases, is secreted by activated macrophages at a late stage of differentiation. Macrophages are present in inflammation of the arterial wall and are thought to participate in the pathogenesis of giant cell arteritis (GCA). The aim of this study was to evaluate whether macrophages and giant cells of patients with GCA produce YKL-40, and whether serum YKL-40 concentrations are elevated in these patients.

METHODS

Serum YKL-40 was determined by radioimmunoassay in 19 patients with GCA and 8 patients with polymyalgia rheumatica (PMR) who were followed up prospectively during 1 year of treatment with prednisolone. Immunohistochemical staining for YKL-40 was performed in temporal artery biopsy samples that were obtained before treatment.

RESULTS

In the arteritic vessels of patients with GCA, positive staining for the YKL-40 antigen was found in CD68+ giant cells and mononuclear cells located in the media. Macrophages located in the adventitia and intima were negative for YKL-40. At the time of diagnosis, patients with GCA had an increased median serum level of YKL-40 (256 microg/liter; P<0.01) compared with healthy age-matched controls (median 118 microg/liter), and the serum level of YKL-40 decreased to normal levels during prednisolone treatment (-38% after 1 month; P<0.001). Most patients with PMR had normal serum YKL-40 levels (median 158 microg/liter) and had no changes in the serum YKL-40 levels during prednisolone treatment. The observed changes in serum YKL-40 did not always parallel the changes in serum C-reactive protein levels and erythrocyte sedimentation rate during the 1-year study period.

CONCLUSION

YKL-40 is found in CD68+ giant cells and mononuclear cells in the media of arteritic vessels of patients with GCA, and the concentration of serum YKL-40 may reflect the local activity of these cells in the inflamed artery.

The distribution of YKL-40 in osteoarthritic and normal human articular cartilage

YKL-40, also called human cartilage glycoprotein-39, is a major secretory protein of human chondrocytes in cell culture. YKL-40 mRNA is expressed by cartilage from patients with rheumatoid arthritis, but is not detectable in normal human cartilage. The aim was to investigate the distribution of YKL-40 in osteoarthritic (n=9) and macroscopically normal (n=5) human articular cartilage, collected from 12 pre-selected areas of the femoral head, to discover a potential role for YKL-40 in cartilage remodelling in osteoarthritis. Immunohistochemical analysis showed that YKL-40 staining was found in chondrocytes of osteoarthritic cartilage mainly in the superficial and middle zone of the cartilage rather than the deep zone. There was a tendency for high number of YKL-40 positive chondrocytes in areas of the femoral head with a considerable biomechanical load. The number of chondrocytes with a positive staining for YKL-40 was in general low in normal cartilage. The present findings, together with previous observations, suggests that YKL-40 may be of importance in cartilage remodelling/degradation of osteoarthritic joints.

Hyaluronan in human deciduous tooth germs in the bell stage. Histochemistry and immunohistochemistry

The primary aim of the present study was a localization of hyaluronan (HA) in human deciduous tooth germs in the bell stage. HA was compared to the content of chondroitin sulfates (CSs). HA was detected with a biotin-labeled HA-binding protein (HABP) and CS with a monoclonal antibody. As controls, enzyme digestions were carried out. Furthermore, the glycosaminoglycans were investigated histochemically with enzyme digestions followed by alcian blue staining. The investigation showed a considerable content of HA in the stellate reticulum, although CS was also found, primarily when treatment with protease was omitted. The dental papilla contained both HA and CS, while the predentin and the dentin contained only CS. The enamel did not contain any CS, but some staining with HABP was observed along the borderline between the ameloblasts and the enamel. The significance of HA in the stellate reticulum is discussed. The importance of carrying out investigations with and without protease digestions is stressed.

Sirius red and acid fuchsin staining mechanisms

The purpose of the study was to investigate the staining mechanism of acid fuchsin and Sirius red. Acid (poly-glutamic acid), neutral (poly-hydroxyproline) and basic (poly-arginine, poly-histidine, poly-lysine) poly-amino acids, collagen types I, II and III, and arginine- and lysine-containing histones were used as test substances applied to nitrocellulose membranes as dot blots. Five micrometer sections of granulation tissue on slides were tested in parallel. Some dots and sections were treated with chloramine-T before staining with acid fuchsin and Sirius red and some with 1 M NaOH after staining. The acid and neutral poly-amino acids were not stained, but the basic amino acids polylysine and poly-arginine, poly-amino acids containing these basic amino acids and the histones and the collagens exhibited intense staining. Oxidative deamination by chloramine-T abolished the staining and 1 M NaOH removed the staining except in the case of poly-arginine. Tissue sections treated in the same way showed a considerable decrease in staining after oxidative deamination with chloramine-T; in particular, the staining of the smaller fibers was abolished. The staining was totally removed by destaining with 1 M NaOH. Therefore, acid fuchsin and Sirius red are not selectively bound to collagen; they are also bound to other proteins containing basic amino acids, and staining to a large extent is influenced by electrostatic forces. The staining seems not to be selective for collagen, and one must account for this when quantitative conclusions are drawn from collagen methods using these stains.

Immunohistochemical quantification of heparan sulfate proteoglycan and collagen IV in skeletal muscle capillary basement membranes of patients with diabetic nephropathy

In IDDM patients, an increased permeability of the glomerular capillaries has been associated with a general loss of negatively charged heparan sulfate proteoglycans (HSPGs) within basement membranes (BMs). In the present study, we used immunohistochemical staining to quantify heparan sulfate (HS), HSPG core protein, and collagen IV in capillary basement membranes of skeletal muscle biopsies taken from 9 healthy control subjects (C) and 20 IDDM patients: 7 with normal albumin excretion rate (<30 mg/24 h) (D0), 5 with incipient nephropathy (albumin excretion rate 30-300 mg/24 h) (D1), and 8 with clinical nephropathy (albumin excretion rate >300 mg/24 h) (D2). In the capillaries, staining was measured by a scanning and integrating microspectrophotometer. A significant difference in the absorbance of HS was found among the four subgroups (means +/- SD): 0.477 +/- 0.082 (C), 0.627 +/- 0.031 (D0), 0.542 +/- 0.098 (D1), and 0.371 +/- 0.118 (D2) (P = 0.006). Similarly, an overall significant difference in the absorbance of collagen IV was demonstrated (means +/- SD): 0.836 +/- 0.111 (C), 0.838 +/- 0.300 (D0), 0.970 +/- 0.173 (D1), and 0.512 +/- 0.248 (D2) (P = 0.02). No statistical difference in the absorbance of core protein was demonstrated among the groups. Within the diabetic groups, HS was inversely correlated to albuminuria (r = -0.76, P = 0.003) and albuminuria corrected for creatinine clearance (r = -0.69, P = 0.008). Because, in IDDM patients with albuminuria, alterations of the content of HS and collagen IV within the capillary BM have been demonstrated immunohistochemically, not only in the glomerular filtration barrier, but also in the skeletal muscle capillary BM, we suggest that these changes reflect universal quantitative or qualitative alterations within the capillary filtration barrier.

Plasma YKL-40: a new potential marker of fibrosis in patients with alcoholic cirrhosis?

BACKGROUND

YKL-40 (human cartilage glycoprotein-39, or 38-kDa heparin-binding glycoprotein) is a mammalian member of a protein family that includes bacterial chitinases. YKL-40 mRNA is expressed by human liver and may play a role in tissue remodelling. The aims were to assess whether circulating YKL-40 is released or extracted in the hepatosplanchnic system and to localize YKL-40 in liver tissue.

METHODS

Plasma YKL-40 was determined by radioimmunoassay in 25 patients with liver diseases (alcoholic cirrhosis (n = 20), chronic active hepatitis (n = 2), cirrhosis of unknown aetiology (n = 2), and fatty liver (n = 1) and in 18 subjects with normal liver function during a haemodynamic investigation with catheterization of liver vein and the femoral artery. Immunohistochemical studies of the localization of YKL-40 in cryostal liver biopsy specimens were obtained from eight other patients with alcoholic liver disease.

RESULTS

Plasma YKL-40 was significantly increased in patients with alcoholic cirrhosis (median, 523 micrograms/l; P < 0.001) compared with controls (106 micrograms/l), and plasma YKL-40 in the hepatic vein was higher (P < 0.01) than that of the artery in both the patients and controls, showing release of YKL-40 from the hepatosplanchnic area. The release rate of YKL-40 from the hepatosplanchnic area was higher in patients with liver disease than in controls (11.0 versus 2.1 micrograms/min, P < 0.05). Furthermore, the highest plasma YKL-40 levels were found in patients with a moderate or severe degree of liver fibrosis, and immunohistochemical studies showed positive staining for YKL-40 antigen in areas of the liver biopsy with fibrosis.

CONCLUSIONS

The increased plasma YKL-40 in patients with alcoholic cirrhosis may reflect the remodelling of liver fibrosis.

Dose response profiles of human growth hormone in subcutaneous wound chambers in rats

OBJECTIVE

To investigate dose response profiles of human growth hormone in soft connective tissue healing when it is given locally in subcutaneous wound chambers.

DESIGN

Placebo controlled parallel study.

SETTING

Institute of Medical Anatomy, Denmark.

MATERIAL

36 male Sprague Dawley rats, in three group of 12.

INTERVENTIONS

Stainless steel wire mesh cylinders 7 mm in diameter and 20 mm long were implanted subcutaneously in pairs in the upper and lower back on either side of the midline in three groups of male Sprague Dawley rats. Two groups were each given two different doses of growth hormone (group 1, 0.2 and 0.7 IU; and group 2, 0.02 and 2 IU) in two cylinders and vehicle alone in the two cylinders on the opposite side. Group 3 were given vehicle alone in two cylinders and needle puncture (sham) on the opposite side. Injections of growth hormone or vehicle (placebo) were given every three days for 16 days.

MAIN OUTCOME MEASURES

Body weight, weight of granulation tissue, and concentrations of hydroxyproline and aminoterminal propeptide of procollagen type III.

RESULTS

The dose response curves for weight of granulation tissue and deposition of collagen were upward convex (ANOVA p < 0.001 and 0.001, respectively). Growth hormone in doses of 0.2 and 0.7 IU stimulated formation of granulation tissue to means of 180% (95% confidence interval (Cl) 149% to 210%) and 174% (95% Cl 148% to 200%) more than in the placebo treated cylinders (group 3) (p < 0.05 and < 0.01, respectively). Doses of 0.2 and 2 IU, however, had less effect. The placebo cylinders in animals in groups 1 and 2 contained a mean of 157% (95% Cl 137% to 177%) more granulation tissue than the cylinders in group 3, indicating that locally applied growth hormone also had a systemic effect.

CONCLUSION

The clinical use of topical growth hormone in wound healing may be complicated by the relatively narrow therapeutic interval.

Effect of craniotomy and cerebrospinal fluid loss on the inner ear. An experimental study

Craniotomy with cerebrospinal fluid (CSF) suction was performed on 18 guinea pigs to determine the effects on the inner ear morphology. Six control animals received anaesthesia only and 12 were operated on with a postoperative survival time of 1 or 24 h. The histologic examinations showed no signs of endolymphatic hydrops or injury to other structures in any of the animals. In 11 of the operated animals, red blood corpuscles were demonstrated in the perilymphatic space of the cochlea, the subarachnoid space, and the cochlear aqueduct (CA). After 1 h survival time blood had entered primarily the basal part of the scala tympani, but in the animals of 24 h survival time the blood was more abundant in both the scala tympani and the scala vestibuli indicating flow within the inner ear. The CA thus provides a pathway between the CSF and the whole of the perilymph through which noxious effects could take place.

The protein effect on determination of DNA with Hoechst 33258

The present study was designed to afford a critical review of the effect of proteins on the Hoechst 33258 method for determination of DNA of crude homogenates. A considerable effect of proteins on the fluorescence was observed when the concentration exceeded 100 micrograms BSA equivalent protein. Below that value, practically no effect of proteins was noted. We used proteinase K to remove the proteins, but dilution of homogenates could be used as well. Moreover, we found that the concentration of the fluorochrome should be between 1 microgram and 2 micrograms when microgram levels DNA are to be determined.

Immunohistochemistry of the intercellular matrix components and the epithelio-mesenchymal junction of the human tooth germ

The immunohistochemical localization of heparan sulphate, collagen type I, III and IV, laminin, tenascin, plasma- and cellular fibronectin was studied in tooth germs from human fetuses. The lamina basalis ameloblastica or membrana preformativa, which separates the pre-ameloblasts from the pre-dentin and dentin, contained heparan sulphate, collagen type IV, laminin and fibronectin. Enamel reacted with antifibronectin, but the reaction varied depending on the type of fibronectin and the source of antibody. In early pre-dentin, collagen type I, laminin, tenascin and fibronectin were present. In late pre-dentin and dentin collagen type I was found in intertubular dentin and in the zone between enamel and dentin. The close relationship between collagen type I in dentin and fibronectin in immature enamel is interesting, as it may contribute to the stabilization of the amelodentinal interface. In dental pulp, collagen type IV and laminin were found in the endothelial basement membranes. Collagen type I and III, tenascin and fibronectin were localized to the mesenchymal intercellular matrix. The results of this study have supported the assumption that the lamina basalis ameloblastica is a basement membrane, and have lead to the suggestion that ameloblasts are producers of fibronectin or a fibronectin-like substance.

Influence of human growth hormone on granulation tissue formation, collagen deposition, and the aminoterminal propeptide of collagen type III in wound chambers in rats

The influence of growth hormone on granulation tissue formation was investigated in wire mesh cylinders implanted subcutaneously in rats. Two groups of 10 rats (study 1) and 1 group of 12 rats (study 2) were used for the investigation. Growth hormone, 0.02 and 0.2 IU (study 1), 0.05 and 0.2 IU (study 2), or vehicle only, was injected into the cylinders every third day for 16 days. In study 2, wound fluid was aspirated before injection of growth hormone and saved for later analysis of the aminoterminal propeptide of collagen type III. In both studies, growth hormone significantly increased the formation of granulation tissue and of total collagen content dose-dependently, whereas the relative amount of collagen was unaffected by growth hormone treatment. Wound fluid aminopropeptide increased significantly after implantation of the cylinders until day 7, before declining slightly, with no difference between the groups. We conclude that growth hormone stimulated granulation tissue formation and collagen deposition dose-dependently in the wound cylinders when injected every third day. The results suggest that growth hormone treatment does not cause excessive collagen deposition in newly formed granulation tissue.

Collagen metabolism during wound healing in rats. The aminoterminal propeptide of type III procollagen in serum and wound fluid in relation to formation of granulation tissue

The aminoterminal propeptide of type III procollagen (PIIINP) in serum has been shown to correlate with fibrillogenesis, and thus to be a potential direct marker of type III collagen deposition. The aim of the study was to investigate the correlation between changes in serum PIIINP and formation of granulation tissue during pharmacological suppression. Granulation tissue was induced in rats by the implantation of viscose cellulose sponges. Pharmacological suppression was achieved by cyclophosphamide treatment. To distinguish between the isolated effect of cyclophosphamide and the influence of the weight loss caused by treatment, weight loss caused by starvation was investigated. In untreated rats, serum PIIINP and wound fluid PIIINP were related to formation of granulation tissue (serum: r = 0.58, p < 0.05; wound fluid: r = 0.56, p < 0.05). In rats treated with cyclophosphamide, collagen deposition and formation of granulation tissue were markedly reduced, as compared within the untreated rats (6% vs 33%, p = 0.01). Wound fluid PIIINP reflected the sparse collagen deposition (r = 0.48, p < 0.05), whereas serum PIIINP decreased (-35%, p < 0.01) and was not correlated with the formation of granulation tissue. In starved rats, with a weight loss of 8%, formation of granulation tissue, vascular density, and collagen deposition were not reduced. Wound fluid PIIINP reflected the formation of granulation tissue (r = 0.52, p < 0.05), whereas serum PIIINP remained unchanged despite normal formation of granulation tissue. Starvation of rats without implants caused a decrease in serum PIIINP (-33%(-)-48%, p < 0.01). We conclude that during cyclophosphamide treatment and after a moderate weight loss, serum PIIINP is not a valid marker of fibrillogenesis. However, in normal rats with free access to food, changes in serum PIIINP mirror fibrillogenesis. Furthermore, our study provides experimental evidence consistent with the hypothesis that wound fluid PIIINP directly mirrors the local formation of granulation tissue, independent of weight loss and cyclophosphamide treatment.

Quantitative PAS assay of some carbohydrate compounds and detergents

A spectrophotometric method for determination of color development of glycocompounds subjected to PAS reaction was investigated with various carbohydrate compounds and related chemicals. The conditions of the oxidation with periodic acid was found to influence the amount of the colored Schiff dye produced. Mono- and di-saccharides (mannose, glucose and maltose) were PAS-negative. Glycogen was more reactive than dextran. When glycogen was hydrolyzed by amylase the intensity of the PAS product dropped until a certain limit probably reflecting the limit dextrin. The presence of proteins (albumin) or electrolytes (NaCl) did not influence the PAS reaction. Many non-ionic detergents commonly used in membrane biology such as alkyl glycosides and gluco-methyl alkanamides were strongly PAS-positive and so was the anionic detergent SDS while the zwitterionic detergents tested, such as CHAPS and CHAPSO, were PAS-negative. The color development of the spectrophotometric PAS reaction showed linearity with the concentration of a simple glycoprotein solution (peroxidase) and a complex solution (bovine serum). By the PAS reaction it was also possible to measure the content of soluble and membrane bound carbohydrate compounds in a pellet of liver cell membranes. We find that the PAS reaction is sensitive and reliable for quantitative estimations of complex carbohydrates as well as soluble and membrane-bound carbohydrate compounds. The latter should be treated with PAS-unreactive zwitterionic detergents.

Changes of soluble glycoproteins in dystrophic (dy/dy) mouse muscle shown by lectin binding

Lectin binding sites in skeletal muscle from normal and dystrophic (dy/dy) C57 BL/6J mice were demonstrated by use of histochemistry and electrophoresis combined with electron microscopy. The following lectins were used: Canavalia ensiformis Con A, Triticum vulgaris (WGA), Glycine max (SBA), Griffonia simplicifolia (GS II), Arachis hypogaea (PNA), Pisum sativum (PSA) and Lens culinaris (LCA). After incubation of frozen sections with Con A, WGA, GS II, PSA and LCA a sarcoplasmic staining was observed in both normal and dystrophic muscle. The most consistent light microscopic observations in the dystrophic muscles were a decreased staining intensity of the sarcoplasm after incubation with Con A, WGA, PSA and LCA, but not with GS II, and a strong staining of the interfiber connective tissue. Supernatants, deprived of organelles and membranes, were prepared from normal and dystrophic muscle by high speed centrifugation. Lectin stained Western blots of the supernatant from dystrophic muscle showed two bands (120 and 67 K) with high affinities to avidin. Further this supernatant contained two glycoprotein bands (180 and 140 K) with affinities to Con A and a number of glycoprotein bands with apparent molecular weights below 67 K showing affinities to LCA and PSA. None of these glycoprotein bands could be detected in the supernatant from normal muscle. These changes of the muscle carbohydrate components might be involved in the expression of the dystrophic syndrome This seems to be the first report on changes of soluble glycoproteins in muscular dystrophy.

Lectin binding in skeletal muscle. Evaluation of alkaline phosphatase conjugated avidin staining procedures

Cryostat sections from rat gracilis muscles were incubated with different biotinylated lectins: Con A (Concanavilin A), WGA (Wheat germ agglutinin), SBA (soybean agglutinin), GS I and GS II (Griffonia simplicifolia agglutinin), LCA (Lens culinaris agglutinin), PNA (peanut agglutinin) and PSA (Pisum sativum agglutinin). The sections were subsequently treated with alkaline phosphatase conjugated avidin. The lectin binding sites were visualized after incubation in substrate media containing: (1) 5-bromo-4-chloro indoxyl phosphate and Nitro Blue tetrazolium or copper sulphate; (2) naphthol AS-MX phosphate or naphthol AS-BI phosphate and various types of diazonium salts; (3) alpha-naphthylphosphate and Fast Blue BB; (4) beta-glycerophosphate according to the method of Gomori. The results obtained with the alkaline phosphatase methods were compared with those seen with a streptavidin-horseradish peroxidase procedure. Several chromogen protocols for visualizing alkaline phosphatase activity showed differences in the ability to detect lectin binding sites. A sarcoplasmic reaction was evident for Con A, GS II, WGA, LCA, and PSA after incubation in the indoxyl phosphate medium. Sarcoplasmic reaction for GS II was also noticed after incubation with naphthol AS-MX Fast Blue BB and beta-glycerophosphate. The latter substrate also gave rise to a sarcoplasmic Con A reaction. With the indoxylphosphate tetrazolium salt method some muscle fibres showed a very strong intracellular reaction after incubation with Con A and GS II while the staining intensity was weak in other fibres. The same muscle fibres were stained with PAS. No sarcoplasmic reactions were observed with either naphthol phosphate media or with the diaminobenzidine peroxidase methods. Further, the staining of the muscle fibre periphery, connective tissue, an capillaries was intensified using the indoxyl method. The indoxylphosphate-tetrazolium salt method seems to be suitable for future investigations of lectin binding sites in muscle sections.

Collagen distribution in developing experimentally induced granulation tissue. A morphometric study

Viscose cellulose sponges were implanted subcutaneously on the back of full-grown Sprague-Dawley rats. Seven, 14, 21, 28, 42, 60 and 90 days after implantation, groups of 12 animals decapitated and the sponges were removed and processed for light microscopy. Five microns sections were stained with Picro-Sirius Red. Morphometry was performed on the zone of ingrowth and the collagen. The intersectional variation in the morphometrically determined collagen density within the sponges was below 20%. The hydroxyproline content was determined biochemically in 5 microns sections of sponges implanted for 14, 42, 60 and 90 days. A positive correlation (rho = 0.79, p less than 0.0001) was observed between the biochemically and morphometrically determined collagen contents. The morphometric determinations showed a steady increase in the granulation tissue ingrowth. At day 60 the ingrowth was complete. There was an increasing collagen density from days 7 and 14 through days 21 and 28, followed by a nearly steady state up to day 90 and a significantly higher collagen density peripherally than centrally in the day 42 sponges. The study has shown that morphometric collagen determination at light microscopical level using Sirius Red-stained sections may add quantitative data describing the dynamic changes in collagen content and distribution within developing granulation tissue.

Injury and repair of smaller muscular and elastic arteries. Immunohistochemical demonstration of fibronectin and fibrinogen/fibrin and their degradation products in rabbit femoral and common carotid arteries following a dilatation injury

Indirect immunoperoxidase staining for fibrinogen/fibrin and fibronectin was performed on normal and healing arterial tissue of muscular and smaller elastic arteries. Fibronectin was observed in the wall of the normal arteries, whereas fibrinogen/fibrin could not be demonstrated. Fibronectin was observed in the intima as well as the media deposited in a similar fashion in the femoral and carotid artery during repair. Apart from the early occurrence of fibrin/fibrinogen in the media of both arteries the distribution of fibrinogen/fibrin and degradation products differed. In the femoral artery a progressively weakening positive reaction for fibrinogen/fibrin and degradation products towards the lumen was observed in the intima and the media 7 and 14 days after the lesion. By 28 days the reaction in the media was negative. No thrombus formation was observed. In contrast, all the specimens examined from the common carotid arteries were obliterated by luminal thrombi 28 days after the lesion. The thrombus as well as the damaged intimal thickening and the compressed media were loaded with fibrinogen/fibrin and degradation products. The deposition of fibronectin, fibrinogen, and degradation products in the carotid artery was similar to that previously reported in experimental aortic arteriosclerosis in rabbits as well as in giant cell arteritis.

Serum aminoterminal type III procollagen peptide. Relation to biosynthesis of collagen type III in experimentally induced granulation tissue in rats

Serum aminoterminal type III procollagen peptide was measured in rats during the development of granulation tissue induced by subcutaneous implantation of viscose cellulose sponges. Active collagen type III synthesis in granulation tissue during the first three weeks was accompanied by an increase in serum propeptide level. A positive correlation was observed between the increase in serum propeptide level on the one hand and the increase in granulation tissue collagen type III content and the in vitro formation of tissue 3H-hydroxyproline on the other hand. In some animals the serum propeptide level remained low, despite biochemical signs of collagen synthesis, indicating variations in the release into serum and/or the metabolism of circulating propeptide. The increase in propeptide antigen concentration was mainly due to an elevated content of material with molecular weight equal to or twice that of the propeptide. A minor fraction of the propeptide remained attached to the interstitial collagen fibres in the granulation tissue. The correlation between the serum propeptide level and the biosynthesis of collagen at the site of the focal fibroproliferative process suggests that the serum propeptide level may be a valuable indicator of fibrogenesis and thereby of disease activity in fibrotic conditions.

Collagen type IV and procollagen type III during granulation tissue formation: a serological, biochemical, immunohistochemical and morphometrical study on the viscose cellulose sponge rat model

The serum concentrations of collagen type IV,7S, collagen type IV,nc1, and aminoterminal type III procollagen peptide immunoreactive components were measured by means of specific radioimmunoassays during development of granulation tissue in rats. The results were compared with tissue deposition of basement membranes and interstitial collagens in the granulation as measured morphometrically. A parallel sequential pattern in tissue deposition of collagen types III and IV, and serum increase of collagen types III- and IV-related fragments, was observed. Serum collagen type IV was less sensitive as a marker for development of granulation tissue than the serum procollagen type III N-peptide. This was in accordance with a low collagen type IV/interstitial collagen ratio in the granulation tissue. However, a cross-sectional study showed that serum collagens types IV,7S and IV,nc1 may be useful as early quantitative indicators of granulation tissue formation. Simultaneously, measurement of collagen type IV- and procollagen type III N-peptide-related antigens in serum provides a differentiated reflection of the dynamic matrix processes in developing granulation tissue.

Giant-cell arteritis. Histological, immunohistochemical and electronmicroscopic studies

Biopsies from the temporal artery of 32 patients suspected of giant-cell arteritis were evaluated retrospectively by light microscopy, histochemical, and immunohistochemical methods, as well as by transmission electron microscopy (TEM). At the clinical follow-up the 32 patients included four clinical groups: temporal arteritis (8 patients), polymyalgia rheumatica (10 patients), rheumatoid arthritis (4 patients), and a group of miscellaneous diseases unrelated to inflammatory rheumatic diseases (10 patients). There were a number of similarities between age-related alterations in the arteries and the changes in giant-cell arteritis. The most important differences were the inflammatory cellular infiltration of the media, the perifocal accumulation of fibronectin, and the occurrence of deposits of fibrin/fibrinogen and fibrin/fibrinogen degradation products. In addition, alpha-2 macroglobulin, lysozyme and factor VIII were also noted in giant-cell arteritis. The alterations in giant-cell arteritis show a number of similarities to the changes following experimental vascular injury of the rabbit aorta. The nature of the findings in human giant-cell arteritis, as well as the similarity to the experimental arteritis, indicate that giant-cell arteritis may reflect a non-specific reaction to injury, independent of the cause of the disease.

Injury and repair of smaller muscular and elastic arteries. A light microscopical study on the different healing patterns of rabbit femoral and carotid arteries following dilatation injuries by a balloon catheter

26 rabbits of the Danish country strain were subjected to mechanical dilatation injury of the left femoral and carotid arteries with Fogarty's embolectomy catheters F2 and F3 respectively. The rabbits were killed 2, 7, 14 and 28 days after the dilatation injury and the arteries examined histologically. Initially both of the arteries exhibited necrosis of the media and infiltration of the vessel wall with neutrophils and mononuclear cells. From day 7, intimal thickening was observed in both types of arteries, progressing in thickness during the later stages. However, thrombosis occurred in the majority of the carotid arteries, whereas this was only infrequently seen in the femoral arteries. In all of the dilated arteries, the elastic laminas were stretched or fragmented and never regained their normal appearance. In the carotid artery, giant cells accumulated around the fragmented elastin and calcified areas, located primarily at the intima-medial border. These changes were never observed in the femoral artery. At the twenty-eight days stage, proliferation of the smooth muscle cells more or less led to restitution of the media in the femoral artery, whereas the carotid artery showed medial restitution only to a lesser extent. The similarities between the injured carotid artery and human temporal arteritis, and the utility of the model as an animal model for the study of temporal arteritis are underlined.

Immune-induced vascular connective tissue alterations in rabbits chronically immunized with bovine serum albumin: morphological and morphometric studies on normal and injured thoracic aorta

The effect of persistent immunostimulation on normal and mechanically injured thoracic aorta was investigated histologically, histochemically and morphometrically. In the uninjured vessel wall no alterations suggestive of acute inflammation were observed following immunization, in accordance with previous biochemical studies. When mechanically elicited vascular injury and repair processes were induced in chronic immunostimulated rabbits, the neo-intimal aortic smooth muscle cell nuclear volume fraction of the vessel wall was significantly repressed, indicating, that the proliferative response to injury was inhibited. Further, the neo-intimal volume fraction of the vessel wall was reduced, suggesting impaired matrix neoformation. A highly significant linear correlation existed between the biochemically estimated DNA concentration and the nuclear volume fraction of smooth muscle cells in the vessel wall (r = 0.6275, P = 5 X 10(-5). Thus, the present study confirms previous biochemical observations, that the early processes of vascular inflammation and repair, i.e. smooth muscle cell proliferation and matrix accumulation, is inhibited following persistent immunostimulation. In addition to describing the histological correlates to the biochemical findings, important regional differences were quantified.

Vascular Injury Compared to Ageing of Normal Rabbit Aorta

Male albino rabbits of the Danish country strain, 5 months of age, were divided into two groups. One group of animals was killed 180 days after a single mechanical dilatation injury of the thoracic aorta. A second group of untreated controls was killed at ages of 150, 165, 180, 210, 330, and 450 days. Glycosaminoglycans, uptake of ³⁵S-sulphate, collagen, uptake of ¹²⁵I-albumin, and vascular histochemistry and morphology were analyzed in the thoracic aorta. In the injured aortae the dry weight and the total amounts of hexosamine, hyaluronic acid, chondroitin-4,6-sulphate, dermatan sulphate, heparan sulphate, and hydroxyprohne were increased. The concentration of hyaluronic acid decreased, whereas the concentration of dermatan sulphate increased. The concentrations of chondroitin-4,6-sulphate and heparan sulphate were unchanged. The total uptake of ³⁵S-sulphate into the sulphated proteoglycans as well as the uptake of ¹²⁵I-albumin were increased. The light microscopical examination showed thickening of the intima, medial changes with fibrosis, accumulations of proteoglycans, calcifications, formation of cartilage, and ossified tissue with haematopoiesis. In the uninjured thoracic aorta the only significant change during ageing was an increase in the total amount of hyaluronic acid and a decrease of the ³⁵S-sulphate incorporation into the chondroitin-4,6-sulphate in the aorta. No morphological or histochemical alterations were observed during ageing. Spontaneous lesions were observed in 2 out of 55 aortas. It may be concluded that injury and ageing are reflected quite differently in the thoracic aorta of the rabbits. The observations may be of relevance to the interpretation of the alterations in human arterial diseases involving processes of injury and repair as well as ageing.

Acid glycosaminoglycans in myxoedema

Acid glycosaminoglycans were measured in the tissues of a virtually untreated 83-year-old woman with myxoedema. Intercellular oedema was demonstrated histologically in the tongue, myocardium, striated muscles, and in the skin. Tissue oedema was absent in two female control patients. All tissues from the patient with myxoedema, apart from the stomach, showed high concentrations of hyaluronic acid, but there was no consistent elevation of chondroitin-4,6-sulphate, heparan sulphate or dermatan sulphate. The accumulation of hyaluronic acid might contribute to the oedema formation in myxoedema.

Scanning and transmission electron microscopy of the normal rabbit aortic endothelium after controlled perfusion fixation

Light microscopy, scanning electron microscopy, and transmission electron microscopy were employed on the anterior wall of the rabbit thoracic aorta with the particular purpose to study endothelial marginal flaps and the structure of stomata under physiological conditions at 100 mm Hg. Intra-aortic pressure monitoring was performed during the whole period of perfusion (2h), restricting pressure variations to a maximum of +/- 5 mm Hg in order to preserve endothelial architecture. We found the endothelial surface uniformly smooth. Marginal flaps of the endothelial cells were mutually overlapping, often forming multiple layers. Underlying flaps might protrude to the lumen between neighbouring flaps as flat mushrooms. Flaps of adjacent cells might diverge for short distances to decover an underlying endothelial cell. Downstream flaps of the cells might be overlapped at their base by flaps of adjacent cells, the extremity of the flap thus appearing as a disc separated from the cell. The small discs and troughs thus formed are considered equivalent to the so-called stomata.

Long-term effect of glucocorticoid on connective tissue of aorta and skin. Morphological and biochemical studies of tissues from rabbits with intact and injured aortas

The long-term effect of prednisolone — 0.6 mg/day for 63 days — upon mechanically induced inflammation and repair processes in vascular connective tissue was compared with that upon undamaged vascular wall and intact skin of rabbits. The investigations included histological examination of aorta as well as biochemical analyses of collagen and various glycosaminoglycan fractions, RNA, DNA and alpha-amino nitrogen. The metabolism of collagen was estimated by in vitro labelling with [14C]proline and the metabolism of glycosaminoglycans by in vivo labelling with [35S]O4. The radioactivity of [125I]albumin in the aorta and serum was also studied.

The collagen, glycosaminoglycans, RNA, DNA and water of vascular connective tissue during inflammation and repair and of intact skin was found to be more sensitive to the action of prednisolone than the connective tissue of undamaged vascular wall. An increased degradation of newly synthesized collagen was observed in damaged aorta as well as in skin in which also the biosynthesis of collagen was inhibited. Prednisolone inhibited the biosynthesis of glycosaminoglycans and decreased the total amount of glycosaminoglycans and of nucleic acids in the damaged aortas and the skin. The [125I]albumin aorta-to-serum ratio was significantly increased in the damaged aorta. Prednisolone treatment decreased the ratio in injured aortas, but elevated the ratio in the undamaged vessels. Prednisolone inhibited intimal thickening of the injured aortas.

Proteoglycans, DNA, and RNA in rat granulation tissue, skin, and aorta. Biochemical and histological studies

Proteoglycans in skin and aorta and nucleic acids in skin were studied in rats with subcutaneous sponge implants and in unoperated rats and compared with the sponge induced granulation tissue during a 42 day period. In rat aorta there was a predominance of the sulphated glycosaminoglycans, in particular heparan sulphate, while in skin there was a predominance of hyaluronic acid and dermatan sulphate. The subcutaneous sponge implantation caused a decrease in the dry weights of skin and aorta but did not influence the concentrations of the measured variables. In aorta the concentrations of chondroitin sulphate and dermatan sulphate decreased with age while in skin there was a slight fall in the concentrations of hyaluronic acid and heparan sulphate with age. The rate of biosynthesis of proteoglycans as estimated from the 35S-sulphate uptake was higher in skin than in aorta. A sequential development was noticed in granulation tissue with an initial high content of hyaluronic acid followed by increasing amounts of chondroitin sulphate and dermatan sulphate in older granulation tissue. The RNA/DNA ratio reached a maximum in 14 day old granulation tissue, but was unchanged in skin throughout the 42 day period. It is concluded that the distribution of proteoglycans and nucleic acids differs from tissue to tissue. This may be of relevance for tissue differences in susceptibility to diseases and to the effects - and side-effects - of drugs. The morphological and biochemical development of sponge induced granulation tissue from rats was similar to other types of granulation tissue during the first 4 weeks.

Endothelial injury of arteries following catheterisation with polyethylene tubes: experimental studies on rabbit aorta using the Seldinger technique

The effect of catheterisation on the rabbit aortic wall is investigated employing a technique identical to that used for continuous monitoring of blood pressure in humans. The catheters were introduced into the aorta through the right femoral artery of the rabbit using the Seldinger technique, except that the catheters were introduced directly into the femoral artery and not percutaneously. It was found that catheterisation for 24 h was followed by intimal and medial injuries. 3 to 60% (mean 20.4%) de-endothelialisation of the aortic surfaces was observed. The present experiments appear to explain some of the complications observed after continuous registration of blood pressure in humans. Case histories are referred to in which the brachial artery was catheterised.

Formation of granulation tissue in subcutaneously implanted sponges in rats. A comparison between granulation tissue developed in viscose cellulose sponges (Visella) and in polyvinyl alcohol sponges (Ivalon)

A comparison was made between the granulation tissue formation in two different synthetic sponge types. Visella and Ivalon, of different sizes. The granulation tissue formed in the two sponge types did not differ qualitatively, and had the character of wound tissue and inflammatory tissue in man. The rate of tissue formation in the Visella sponges was faster and the tissue was more homogenous than in the Ivalon sponges. Fourteen-day-old Visella implants of either size contained more granulation tissue than Ivalon sponges, probably owing to the smaller pore size of the former material. This may also account for the more frequent occurrence of giant cells in the Visella implants. In contrast to the Visella sponges, the trabeculae of the Ivalon polymer showed calcification and positive staining properties with histological staining procedures, and deformation was frequent among the Ivalon implants. Thin sponges of either type closed in about 21 days, thick ones after about 42 days of implantation. Calculated per 2 cm3 of implant, thin sponges produced more tissue after 14 days of implantation than thick noes. It is concluded that the Visella sponge type is best suitable for this experimental model of inflammation.

Increased collagen prolyl hydroxylase activity in the aortic wall of rabbits exposed to chronic hypoxia

The activity of collagen prolyl hydroxylase in aortic wall was studied in rabbits exposed to chronic 10% ambient oxygen tension for 30 days. Prolyl hydroxylase in rabbit aorta was shown to be similar to the enzyme from other sources in that it required molecular oxygen, alpha-ketoglutarate, ferrous iron and ascorbate for its activity. The activity of prolyl hydroxylase was increased to 180% of controls in the intima-media samples from rabbits exposed to hypoxia. No atherosclerotic lesions could be seen in arteries of animals kept in chronic hypoxia. If the arteries of rabbits were injured with a single mechanical dilatation, the activity of prolyl hydroxylase increased more than 2-fold, as reported previously. The exposure of these animals to chronic hypoxia further elevated the prolyl hydroxylase activity.

Succinate dehydrogenase activity in the wall of rabbit aorta. The histochemical use of PMS and exogenous coenzyme Q10 as intermediate carriers

An investigation of succinate dehydrogenase activity in the wall of rabbit aorta was carried out. The level of succinate dehydrogenase per se in the smooth muscle cells was found to be fairly high, while the mitochondrial level of carrier CoQ was low. The latter may explain the low level or lack of activity of succinate dehydrogenase in these cells as noticed by previous authors. A reliable image of the actual level of succinate dehydrogenase was obtained only by adding CoQ10 to the incubation system. PMS should be avoided, as it induced a "Nothing dehydrogenase" reaction even at low concentrations.

Glucocorticoid effects on vascular connective tissue during repair. Importance of dose level and pre- and post-injury treatment. Morphological and biochemical studies

Aorta of male albino rabbits were subjected to a single mechanical dilatation injury and the effects of different daily doses of prednisolone on the metabolism of collagen and glycosaminoglycans as well as on the content of alpha-amino nitrogen, RNA, DNA, water and fat and the histology of the descending thoracic aorta were analyzed 10 days after the injury. The effects of pre- and post-injury treatment with prednisolone were compared.

Prednisolone inhibited the intimal thickening. This effect was enhanced by pre-injury treatment.

Prednisolone also inhibited the biosynthesis of non-dialysable [14C]hydroxyproline-collagen, but increased the relative degradation of collagen in a dose dependent manner. The biosynthesis of glycosaminoglycans was decreased while prednisolone had no effect on the concentration and total amount of glycosaminoglycans, collagen, protein, RNA, DNA and fat. Finally the aortic content of water was decreased during treatment with prednisolone also in a dose dependent manner.

It is concluded that the action of prednisolone on vascular collagen and water during repair is dose dependent and that the inhibitory action of prednisolone on the intimal thickening is enhanced by pre-injury treatment.

Glucocorticoid effect on repair processes in vascular connective tissue. Morphological examination and biochemical studies on collagen RNA and DNA in rabbit aorta

Male rabbits were injured by a single mechanical dilatation of the aorta and then injected with prednisone 2 mg/kg saline for 14 days or starved. Morphological studies and biochemical measurements of the collagen metabolism, the content of alpha-amino nitrogen, RNA, DNA, water and fat, and the aorta to serum ratio of 125I-albumin were performed on the intima-media layer of the descending thoracic aorta. Prednisone inhibited the intimal thickening. In the media the infiltration by mononuclear cells, the proliferation and regeneration of the smooth muscle cells and the calcification were reduced. Prednisone caused a decrease in 0.45 M NaCl soluble collagen as well as in the dialysable and non-dialysable 14C-hydroxyproline fractions. The total amount of collagen, elastin and alpha-amino nitrogen was unchanged, whereas the 14C-proline incorporation in the non-dialysable protein fraction was inhibited to a greater extent than the 14C-hydroxyproline synthesis. The findings indicate that prednisone inhibits the biosynthesis of collagen, which is inhibited to a greater extent than the general protein synthesis. Prednisone increased the dialysable to non-dialysable 14C-hydroxyproline ratio consistent with a relative increase in the catabolism of newly synthesized collagen. The aortic content of RNA and DNA was reduced consistent with the inhibition of protein synthesis and cell proliferation. Finally prednisone decreased the aortic content of water when related to the wet weight and increased the aortic content of fat. The aorta to serum ratio of 125I-albumin was not influenced by prednisone. It is concluded that administration of glucocorticoid for 14 days exerts an inhibitory action on the histological reaction to injury as well as on the biosynthesis of collagen of the repair processes in vascular connective tissue. A comparison with the effects of prednisone on undamaged rabbit aorta (Manthorpe et al. 1974) demonstrates that the metabolism of collagen of vascular connective tissue during repair is more sensitive to the antianabolic effects of prednisone than collagen in the non-injured aorta. Starvation caused an increase of the aortic percentage of water but otherwise had no influence on the repair processes in the vascular connective tissue.

Effects of intermittent and continuous hypoxia on the aortic wall in rabbits

Male albino rabbits were exposed to intermittent nitrogen breathing every 30 sec for 5 sec, 15 min daily over a period of 3 weeks, and every 30 sec for 5 sec over a period of 10 hr. A third group of animals was exposed continuously to 8% oxygen breathing for 2 weeks. Neither intermittent not continuous hypoxia induced gross or microscopic alteration in the aorta. The effects of hypoxia upg which hypoxia was distributed than upon the total period or the degree of hypoxia. Exposure to hypoxia over a short period stimulated the synthesis of glycosaminoglycans, whereas distribution of the hypoxia over a longer period resulted in a reduction in the amount of glycosaminoglycans, probably secondary to an inhibition of the synthesis. Similarly, continuous exposure to 8% oxygen for a longer period decreased the aortic content of collagen. The alterations in the glycosaminoglycans and collagen induced by hypoxia may cause changes in the passage of macromolecules through the aortic wall. The changes may also influence the mechanical properties of the aorta and lead to impaired healing of vascular injury.

A scanning electron microscopic (SEM) study on the endothelium of the normal rabbit aorta

In scanning electron microscopic (SEM) studies the appearance of the normal endothelial surface of the rabbit thoracic aorta was considered. The intercellular bridges described by other authors as elements of the normal endothelial surface were interpreted as artifacts in this study. In silver stained preparations the endothelial cells appeared as oblong rhombic fields depicted by sinuous silver lines and with their long axes forming acute angles with the coarse longitudinal folds produced by the first elastic lamella. The endothelial surface was smooth, the nuclei were faintly visible and in unstained specimens cell boundaries were not clearly demarcated. Artifacts probably produced by fixation, dehydration, air drying and coating were frequent, appearing as shrinkage, tissue rupture and curling up of the cells.

Repair in arterial tissue. Morphological and biochemical changes in rabbit aorta after a single dilatation injury

Male albino rabbits were subjected to a single mechanical dilatation of the descending thoracic aorta with a balloon catheter. The animals were killed 3, 6, 14, 30, and 60 days later. Between the sixth and the fourteenth days after injury, all the aortas which had been dilated developed severe, gross arteriosclerosis. Microscopic examination showed destruction and degeneration in the form of necrosis and calcification as well as regeneration and repair including new formation of cells, intercellular substance, and fibers. Biochemical and histochemical analyses revealed an early increase in hyaluronic acid and water followed by an increase in chondroitin-4, 6-sulfate and a later increase in heparan sulfate, dermatan sulfate, and collagen. These alterations were related to the focal lesions in the aortic wall. The permeability of the aorta to 125 I-albumin increased to a maximum 3 days after the dilatation, whereupon it decreased rapidly. The alterations were interpreted as nonspecific processes of repair in the vascular connective tissue. The pronounced dependence of the alterations on the time elapsed after injury must be considered in the study of vascular diseases where injury and repair may be involved.