Arteriolo-venular anastomoses in the synovial membrane of the knee joint

The arteriolo-venular anastomoses (AVA) in the synovial membrane of the knee joint of fetuses (40), corpses of persons at various age (120) and dogs (30) have been studied by means of the impregnation method after V. V. Kupriyanov. In the synovial membrane shunts and semishunts are revealed. The AVA localize in composition of the deep vascular network of the synovial membrane. They are dynamic structures. The occurrence of their disclosure and their structure depend on the age factor.     

Ultrastructural changes in the synovial membrane in experimentally-induced osteoarthritis of rabbit knee joint.

Rabbit knee joint osteoarthritis was induced by intraarticular injections of a 10% sterile NaCl solution. Within 30 days the synovial membrane had undergone hyperplasia resulting in activated synovial fibroblasts. Transitional forms of synoviocytes as well as activated synovial macrophages were a very common finding. At 60 days a thickening of the synovial intima was perceptible. Most of the synoviocytes were of the fibroblast type. Transitional cell forms abounded. An increase in collagen fibres and capillaries of the fenestrated type occurred in the intercellular spaces. In the deep layer collagen bundles had formed between which activated fibroblasts and macrophages were noticed. The described changes point to an active participation of the synovial membrane in the destruction of articular cartilage in osteoarthritis.     

Influences of sulfated glycosaminoglycans on biosynthesis of hyaluronic acid in rabbit knee synovial membrane

The effect of various sulfated glycosaminoglycans on glycoconjugates syntheses in synovial membranes of rabbit knee joints in culture was investigated by two different approaches. In the first approach, synovial membranes isolated from rabbit knee joints were cultured in the presence of sulfated glycosaminoglycans and [14C]glucosamine. In the second approach, solutions of sulfated glycosaminoglycans were injected into rabbit knee joints and synovial membranes isolated from the joints were cultured in the presence of [14C]glucosamine. The major part of [14C]glucosamine-labeled glycoconjugates associated with the synovial membranes and secreted into culture medium was hyaluronic acid. Of the natural glycosaminoglycans tested, dermatan sulfate gave the maximum stimulation of hyaluronic acid synthesis followed by chondroitin 4- and 6-sulfate. Heparin, heparan sulfate, keratan sulfate, keratan polysulfate, and hyaluronic acid had no significant effect. Of the chemically polysulfated glycosaminoglycans, GAGPS (a persulfated derivative of chondroitin sulfate) gave high stimulation but N-acetylchitosan 3,6-disulfate had no effect. The effect of sulfated glycosaminoglycans on hyaluronic acid synthesis was the same in both experimental approaches. The increase in the amount of secreted hyaluronic acid in culture medium paralleled that in synovial membranes. The results indicate that the galactosamine-containing sulfated glycosaminoglycans have a specific stimulatory effect on hyaluronic acid synthesis. A high degree of sulfation of the molecules appeared to potentiate the stimulatory effect.     

gamma-Aminobutyric acid in peripheral tissues

Significant amounts of gamma-aminobutyric acid (GABA), an endogenous amino acid, are present in mammalian peripheral tissues. This finding led to the suggestion that GABA may act as a neurotransmitter in the peripheral nervous system as it does in the central nervous system. This review deals with recent identification of GABA in the autonomic nervous system and the possible functional role of GABA in neuronal and non-neuronal tissues. The identification of GABA in the autonomic nervous system has paved the way for new approaches in pharmacological investigations.     

Development and morphology of rat synovial membrane

The development of the knee joint and synovial membrane in Wistar rats was studied from the 13th fetal day until adulthood by means of light microscopy, transmission electron microscopy and scanning electron microscopy. Using acid phosphatase and peroxidase methods, the different cell types of synovial membrane could be identified.     

ATPase and Adpase activities in synovial membrane of equine metacarpophalangeal joint

ATPase and ADPase activities capable of hydrolyzing nucleoside di- and triphosphates in the presence of Ca2+ are present in synovial membrane of metacarpophalangeal joint mainly associated to membrane fractions. These hydrolytic activities have been considered involved in the inflammatory process where ATP and ADP are inflammatory mediators while adenosine counteracts this effect. Both, subcellular localization and kinetic properties of these nucleotidase activities, suggest that could correspond to single enzyme called ATP-diphosphohydrolase or apyrase. The comparison of the activity on ATP-Ca and ADP-Ca from normal and pathological equine synovial membrane did not show significant differences either in the subcellular fraction distribution or in the enrichment of each subcellular fraction. Neither differences on 5'-nucleotidase activity present in the microsomal fraction were observed.     

Innervation of the synovial membrane of the cats joint capsule

Summary Results of investigations on the occurrence of nerve fibres and endings in the synovial membrane of the knee and elbow joint in the cat are reported. The stratum synoviale contains only autonomic fibres, running in the adventitia of arteries.Free nerve endings are lacking in the stratum synoviale. Simple Pacinian corpuscles with an inner core are occasionally observed in the border zone between the stratum synoviale and fibrosum. The ultrastructure of these endorgans resembles that of Pacinian corpuscles in the hairless and hairy skin of the cat.     

gamma-Aminobutyric acid receptors in brain postsynaptic densities

Rat brain synaptic plasma membranes contain two receptorlike binding sites for the inhibitory transmitter gamma-aminobutyric acid. Postsynaptic junctional structures (postsynaptic densities) isolated from these membranes contain only the higher affinity site enriched more than sixfold compared to the membranes. The results provide the first direct evidence for the association of transmitter receptors with postsynaptic junctional sites in the brain.     

Ultrastructural study of synovial membrane from the antebrachiocarpal joint of calves

The synovial intima from the antebrachiocarpal joint of 4-month-old calves was between 1 and 3 cells in thickness and did not have a basal lamina. Numerous areas of the intimal matrix were in direct contact with the joint lumen. The synovial membrane was comprised mainly of A-type synoviocytes usually located adjacent to the joint lumen. These cells were characterized by numerous filopodia (or lamellipodia), large, empty-appearing vacuoles, numerous lysosomes, large vacuoles containing granular material separated from the vacuolar membrane by a radiolucent band, and coated micropinocytotic vesicles. Smooth micropinocytotic vesicles were seen only rarely in these cells. In contrast, B-type cells had few filopodia, numerous smooth micropinocytotic vesicles, few coated micropinocytotic vesicles, a well-developed Golgi apparatus and rough endoplasmic reticulum, mitochondria that were longer and had a denser matrix than that of A cell mitochondria, and surprisingly, only few maturing or fully formed secretory granules. A distinct intermediate (C or AB) type synoviocyte could not be unequivocally identified. Desmosome-like structures were present between synoviocytes, although it was considered questionable if these were true intercellular junctions. No other junctions were present.     

Extracellular appearance of calpain and calpastatin in the synovial fluid of the knee joint

Extracellular location of calpain and calpastatin was demonstrated in the cell-free synovial fluid obtained from the knee joint of healthy adult humans and several patients with rheumatoid arthritis. Calpains I and II and a few molecular species of calpastatin were identified by chromatographies on DEAE-cellulose and on Ultrogel AcA 34 columns as well as by immunoelectrophoretic blot analysis. Calpains I and II in the synovial fluid of the patients increased 6.7 times and 3.5 times, respectively, compared with those of the control subjects. With the patients, shortening of the heavy subunits of calpains was noted. Calpastatin also increased in the patients, but it showed rather extensive fragmentation.     

Glycosaminoglycan polysulfate-induced stimulation of hyaluronic acid synthesis in rabbit knee synovial membrane: involvement of binding protein and calcium ion

We have previously reported that naturally occurring sulfated glycosaminoglycans having a chondroitin-type structure and glycosaminoglycan polysulfate (GAGPS, a persulfated derivative of chondroitin sulfate) caused a specific stimulation of hyaluronic acid synthesis in rabbit knee synovial membranes [H. Nishikawa et al. (1985) Arch. Biochem. Biophys. 240, 146-153]. In the present study, the interaction of [3H]GAGPS and the surface of the rabbit knee synovial membranes and the relationship between this interaction and the stimulatory effect of GAGPS on the hyaluronic acid synthesis were examined in order to define the stimulatory mechanism of hyaluronic acid synthesis by GAGPS. A part of the [3H]GAGPS taken up by the synovial membranes was released from the membranes by trypsin treatment. The interaction of [3H]GAGPS and the surface of the isolated synovial membranes was diminished by pretreatment of the membranes with proteases or chelating reagents. Pretreatment of synovial membranes with trypsin or ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid had little effect on the basal hyaluronic acid synthesis but caused the loss of GAGPS-induced stimulation of hyaluronic acid synthesis accompanied by significant decrease (20% P less than 0.05-P less than 0.01) in the interaction between GAGPS and the surface of the synovial membranes. Dermatan sulfate having a chondroitin-type structure also stimulated hyaluronic acid synthesis but this effect was not additive to the stimulation of hyaluronic acid synthesis by GAGPS. Heparin had no effect on either the basal hyaluronic acid synthesis or the GAGPS-induced stimulation of hyaluronic acid synthesis. These results indicate that binding of GAGPS to certain distinct protein components on the surface of synovial membranes is involved in the stimulatory mechanism of hyaluronic acid synthesis by GAGPS, and that the binding may be mediated by Ca2+ ion. The binding was also found to be specific for sulfated glycosaminoglycans having a chondroitin-type structure.     

Preparation of rat synovial membrane for studies of cytokine secretion

The objective of this work was to devise an in vitro system for studies on cytokine secretion by synovial membrane treated as a whole organ with various synoviocyte populations. Synovial membrane from knee joints of WAG rats was dissected and incubated in culture medium without serum for 4 - 48 h. The level of IL-1alpha was determined in synovial lysates and IL-6 in culture medium. The synovial membrane from left and right knee joint of the same rat produced similar amount of cytokines both in lysates and in the medium. Synovial membrane stimulated by LPS for 4 or 24 h gave significantly stronger cytokine response than the membrane from the opposite (control) knee. After 48 h incubation of synovial membrane drastic drop in cytokine level was noted, which indicated on deterioration of the membranes. The test may be useful in studies on factors affecting cytokine secretion by synoviocytes.     

Ontogenetic development of synovial A cells in fetal and neonatal rat knee joints

Summary Ontogenetic development of the synovial A cells in fetal rat knee joints was investigated by immunohistochemistry, immuno-electron microscopy, cultivation, and autoradiography. At day 17 of gestation, immature macrophages were first seen in the articular interzone, and thereafter they differentiated into macrophages (synovial A cells), which were found in the synovial intima. The degree of reactivity of macrophages with five monoclonal antibodies increased in the developing synovial membranes of fetal rats as shown by immunohistochemistry. Similar findings were obtained in organ cultures of fetal knee joints. A marked difference of proliferative potential was found between A and B cells during ontogeny. A cells after birth did not incorporate ³H-thymidine in contrast to B cells. Before birth, B cells had a labelling index which was at least five times larger than that of A cells. The results of this study indicate that the synovial A cells are derived from both monocytes and fetal macrophages circulating in peripheral blood and that they differ from the synovial B cells in morphology, differentiation, and proliferative potential.     

gamma-Aminobutyric acid transport in reconstituted preparations from rat brain: coupled sodium and chloride fluxes

Transport of gamma-aminobutyric acid (GABA) is electrogenic and completely depends on the presence of both sodium and chloride ions. These ions appear to be cotransported with gamma-aminobutyric acid through its transporter [reviewed in Kanner, B. I. (1983) Biochim. Biophys. Acta 726, 293-316]. Using proteoliposomes into which a partially purified gamma-aminobutyric acid transporter preparation was reconstituted, we have been able--for the first time--to provide direct evidence for sodium- and chloride-coupled gamma-aminobutyric acid transport. This has been done by measuring the fluxes of 22Na+, 36Cl-, and [3H]GABA. These fluxes have the following characteristics: There are components of the net fluxes of sodium and chloride that are gamma-aminobutyric acid dependent. The sodium flux is chloride dependent; i.e., when Cl- is replaced by inorganic phosphate or by SO4(2-), gamma-aminobutyric acid dependent sodium fluxes are abolished. The chloride flux is sodium dependent; i.e., when Na+ is replaced by Tris+ or by Li+, gamma-aminobutyric acid dependent chloride fluxes are abolished. Thus, the gamma-aminobutyric acid dependent sodium and chloride fluxes appear to be catalyzed by the transporter. Using these fluxes we have attempted to determine the stoichiometry of the process. We measured the initial rate of sodium-dependent gamma-aminobutyric acid fluxes and that of gamma-aminobutyric acid dependent sodium fluxes. This yields the stoichiometry between sodium and gamma-aminobutyric acid (2.58 +/- 0.99). Similarly, we measured the stoichiometry between chloride and gamma-aminobutyric acid, which is found to be 1.27 +/- 0.12.(ABSTRACT TRUNCATED AT 250 WORDS)