PubMed Health⌕ Search

Biomedical subjects

E C Carlson

Publications and source records attributed to E C Carlson.

17 recordsLinked to original sources
PubMed1992

Inhibition of bovine retinal microvascular pericyte proliferation in vitro by adenosine.

Adenosine acts on bovine retinal microvascular pericytes through one or more adenosine receptor subtypes present on the cell surface. Retinal pericytes cultured in medium containing adenosine at concentrations from 10(-6) to 10(-4) M showed significant reduction in proliferation following several days in vitro compared with control cultures. The effects of adenosine were mimicked by polyadenylic acid and inhibited by 8-phenyltheophylline, indicating involvement of a cell surface receptor. Metabolites of adenosine had no effect on pericyte proliferation. An A2 adenosine receptor-specific analogue also inhibited pericyte growth, suggesting that inhibition by adenosine is mediated by A2-receptors and might involve a transient increase in adenosine 3',5'-cyclic monophosphate levels. The results of the present study demonstrate that in addition to demonstrated stimulatory effects on capillary endothelial cells, adenosine also has a direct inhibitory effect on retinal pericytes. We hypothesize a dual function of adenosine within the capillary wall resulting in loss of inhibition of endothelial cells and suggest a role for this nucleoside in pathological neovascularization processes such as proliferative diabetic retinopathy.

Adenosine↗
PubMed1992

Capillary endothelial cells secrete a heparin-binding mitogen for pericytes.

The cells of the retinal microvasculature consist predominantly of mesodermally derived pericytes and endothelial cells, and the regulatory factors which govern their co-ordinated growth and define their phenotypic characteristics in vivo may be regarded as key elements of the angiogenic process. An investigation of these cells in co-culture experiments has led to the identification of a potent mitogen for pericytes in medium conditioned by retinal endothelial cells (EC-FBS). EC-FBS activity was shown to be non-dialyzable, and stable to both heat and acid treatment. EC-FBS was inactivated by passage over a heparin-Agarose column. The column-bound activity could be eluted as a single peak at approximately 1.0 M NaCl. Stimulation of pericyte growth was also achieved with platelet-derived growth factor (PDGF), acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) and could be blocked by using the appropriate antiserum (anti-PDGF or anti-aFGF). Neither antisera, however, blocked the activity of EC-FBS. The EC-FBS mitogen markedly altered the phenotypic behavior of pericytes compared with PDGF and the FGFs; yet, unlike them, it failed to stimulate the growth of smooth muscle cells (SMC) and Balb/c 3T3 cells.

Animals↗
PubMed1979

Biosynthesis of basement membrane matrix by isolated rat renal glomeruli.

The incorporation of radioactive precursors into the extracellular basement membrane matrix has been investigated in a purified preparation of isolated rat kidney glomeruli. Using deoxycholate extraction of isolated glomeruli which were incubated with radioactively labeled amino acids and carbohydrates, as an assay system for the measurement of incorporation of basement membrane precursors into intact deoxycholate insoluble basement membrane material, we demonstrated the in vitro biosynthesis of this structure. The assay system minimized the possibility of contamination of the isolated labeled basement membrane with labeled cell membrane fragments which may occur with the standard isolation procedures involving sonication and centrifugation. A linear incorporation of labeled proline, lysine, glycine, glucosamine, and galactose into glomerular basement membrane was shown. Basement membrane synthesis was inhibited by metabolic poisons and protein synthesis inhibitors as well as by inhibitors of collagen synthesis, but not by colchicine, an inhibitor of collagen secretion. Rhe appearance of 14C-hydroxyproline in the basement membrane matrix was negligible during the first 4 hours of incubation and rose only to 1% of the total proline counts thereafter. The results are consistent with the characterization of glomerular basement membrane synthesis and deposition as a two component system comprising a rapidly synthesized and deposited noncollagenous glycoprotein component(s) and a collagenous component which is only deposited after a delay of 4 to 6 hours.

Aminopropionitrile↗
PubMed1978

An ultrastructural study of developing extracellular matrix in vitelline blood vessels of the early chick embryo.

This investigation was designed to describe the morphological events in embryonic development of peripheral blood vessels (vasculogenesis) and to relate this process to the appearance of extracellular matrix (ECM) during growth and maturation of these tissues. Extraembryonic vitelline vessels of the early chick embryo were chosen for this study and light, transmission, and scanning electron microscopy were carried out on vessels excised from chick embryos (Hamburger-Hamilton stages 8 through 23). Our data show that early (stage 10) vessels are composed of two distinct epithelial layers, an inner layer of presumptive endothelium surrounded by a layer of splanchnopleuric mesoderm. During development, the inner layer gives rise to mature vascular endothelium while splanchnopleuric mesoderm differentiates to form primitive vascular smooth muscle. Ultrastructural studies show the presence of collagen and basal lamina in the extracellular space between these two layers during initiation of endothelial and smooth muscle cytodifferentiation. Furthermore, ruthenium red-positive material is present on basal surfaces of developing vascular endothelium at this time, indicating possible glycosaminoglycans (GAG) or other polyanionic components of the ECM. These data suggest that the sequential production of basal lamina, collagen (s), and/or GAG's by developing peripheral vessel wall epithelia may be critical to their final differentiation.

Animals↗
PubMed1977

Isolation and characterization of myocytes from the adult rat heart.

Spontaneously contracting myocytes were isolated from ventricles of the adult rat heart. Hearts were perfused retrogradally via the aorta for 30 minutes at 37 degrees C with Ca2+-free phosphate-buffered saline containing collagenase and hyaluronidase. The venticles were divided into pieces and incubated 15 minutes with the enzymes. Dislodged cells were decanted, diluted with cold buffer and allowed to settle. The washed cells were then sedimented through 3% Ficoll. This procedure yielded approximately 50 mg of protein from 1 gm of heart. Viability measured by trypan-glue exclusion is 90-95%. Approximately 80% of the cells were beating. Scanning electron microscopic studies suggest that the isolated myocytes are morphologically intact. The cells oxidize glucose, pyruvate, citrate and palmitate to CO2 and synthesize protein and RNA. Uptake of glucose, 2-deoxyglucose, leucine and taurine was saturable. Glucose uptake was stimulated by insulin. The cells retained LDH and CPK as well as their capacity to oxidize substrates after 24 hours at 4 degrees C or 4 hours at 37 degrees C. After 24 hours at 4 degrees C the cells resume contracting when returned to room temperature. The procedure reported here for the isolation of spontaneously contracting, adult, rat heart myocytes provides cells with a high index of viability and greater yield than previously reported methods. The cells retain metabolic activity and withstand storage for longer periods than other described preparations.

Amino Acids↗
PubMed1977

Effect of zinc on peritoneal macrophages in vitro.

Rat peritoneal macrophages incubated in a medium with 10% autologous serum showed 50% inhibition of O2 consumption by 0.4 mM zinc only when activated by yeast. Zinc ions had no effect on resting macrophages. The inhibitory efficiency of zinc depended on the ratio of yeast particles to macrophages; with more activated cells, the inhibition was less. The multiple-shaped intact macrophages changed into rounded cells in the presence of 0.1 and 0.5 mM Zn2+ as shown by photomicrography and scanning electron microscopy. When the incubation medium was replaced by zinc-free medium, cells recovered and became irregularly shaped. The reversibility of zinc effect on cell morphology corresponded with uptake and release of zinc by macrophages. The presence of serum in the medium interfered with the magnitude of zinc uptake by macrophages. We conclude that besides already reported effects of zinc on mast cells, platelets, and granulocytes, zinc ions also inhibit some functions of macrophages.

Animals↗
PubMed1976

Early changes in the arterial wall of chickens fed a cholesterol diet.

A total of 160 1-2 day old chickens were fed a 2% cholesterol diet for a period of 8 to 42 days and compared with an equal number of controls. Aortas were analyzed for various indexes of reactivity of connective tissue, cholesterol content and scanning electron microscopy (SEM) characteristics of the endothelial lining. Cholesterol feeding for a period up to 6 weeks resulted in doubling the level of serum cholesterol. It was, however, without effect on the activity of prolyl hydroxylase, lysyl oxidase, collagenase and collagen content in the aortic wall. As early as 3 weeks of feeding significant changes occurred in total and esterified cholesterol content. At the same time endothelial cells were characteristically contracted with several long cytoplasmic elongations and protrusions. A significant decrease of activity of the above enzymes was found in aortic tissue with increased age of the chicken. Collagen content in aortas increased with age of chickens. It is concluded that cholesterol as an atherogenic agent induces marked changes in endothelial cells and lipids of chicken aorta at earlier periods, prior to the activation of connective tissue.

Animals↗
PubMed1975

The development of proline-containing extracellular connective tissue fibrils by chick notochordal epithelium in vitro.

Notochords were isolated from Hamburger-Hamilton stages 13-15 chick embryos by trypsinization and microdissection. These were shown by electron microscopy to be completely devoid of extracellular materials or mesenchymal contaminants. Cultivation of notochordal isolates was carried out on a non-collagenous (Falcon Plastic) substratum for 0 to 48 hours. At 12 hours of in vitro incubation, a discontinuous basal lamina could be demonstrated on the surface of notochordal cells. This was followed by the appearance of microfibrils of various sizes and other components of the extracellular matrix. By 48 hours of in vitro incubation, the same extracellular materials which surround the notochord in vivo (notochord sheath) could be demonstrated in vitro. Autoradiographic studies show that tritiated proline is taken up by notochordal cells and secreted to the extracellular space where label is associated with basal lamina, microfibrils and ground substance. When cis-hydroxyproline, a known collagen-specific inhibitor is added to the system, tritiated proline label is located primarily intracellularly and fewer areas of active fibrillogenesis are noted. This suggests that ultrastructurally recognizable materials produced by notochordal cells in vitro may be at least partially collagenous. Significantly, these materials are produced in vivo at the same time (following stage 10) that notochordal tissues actively induce somite differentiation and cartilage formation. It seems reasonable that a biochemically or ultrastructurally identifiable component of the extracellular matrix may possibly mediate such induction.

Animals↗
PubMed1975

Properties and origins of infectious rhinovirus type 14 particles of different buoyant densities.

Isopycnic centrifugation of rhinovirus type 14 (RV14), purified from infected HeLa or KB cell cultures, into CsCl gradients resolved two bands of infectious virus particles with buoyant density values of 1.409 +/- 0.007 (H virus) and 1.386 +/- 0.004 (L virus) g/ml. Only H virus was detected by incorporation of radiolabeled uridine into viral RNA, and H virus accounted for the majority of infectivity in gradients. H and L virus could not be differentiated by plaque morphology, extent of neutralization by RV14-specific antiserum, or particle size. Electron microscope studies showed that most L-virus particles were associated with an amorphous material. Treatment of L virus with proteolytic enzymes or rebanding L virus in CsCl gradients resulted in recovery of the majority of infectivity as H virus. Virus purified from cell-free fluids from infected HeLa or KB cell cultures banded only as H virus. HeLa cell cultures challenged with purified H virus and harvested at 3 h postinoculation for virus purification yielded only infectious H virus. Both H and L viruses were detected in cell cultures that had been challenged with purified H virus and harvested at 12 h postinoculation. The data suggest that H virus represents progeny virus, whereas L virus represents sequestered infectious virus particles which become associated with an amorphous material and do not enter into viral replicative processes.

Adsorption↗
PubMed1975

Presence of modified fibroblasts in ischemic contracture of the intrinsic musculature of the hand.

Biopsies of fibrotic interosseous muscles were obtained from three patients with ischemic contracture of the intrinsic muscles of the hand. Control biopsies were taken from normal contralateral interossei and from normal interossei crushed three weeks earlier. Examination of the specimens from the affected muscles under the electron microscope demonstrated large numbers of modified fibroblasts with ultrastructural features of both fibroblasts and smooth muscle cells. The atypical fibroblasts observed resembled myofibroblasts seen in contracting wounds, Dupuytren's contracture, stenosing tenosynovitis, and idiopathic carpel tunnel syndrome. Biopsies from normal muscle and crushed normal muscle contained normal fibroblasts and smooth muscle cells but no modified fibroblasts. Active contraction of modified fibroblasts could be responsible for progressive muscle shortening seen in intrinsic contracture.

Adolescent↗