Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
J Colloid Interface Sci ; 247(1): 107-16, 2002 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-16290445

RESUMEN

Coal is an organic sedimentary rock composed of organic macerals and mineral matter. As it is demonstrated in this paper the discrete mineralogical nature of coal largely influences the wetting of the coal surface by water. Both advancing and receding contact angles were measured using the captive-bubble technique with an automatic bubble shape analysis software. The distribution and amount of mineral inclusions on the coal surface were determined by scanning electron microscopy and examined using the image analysis system. To determine the amount and size distribution of mineral grains, the coal surface layer, on which the contact angles were measured, was separated from the larger piece used in the measurements by microslicing. The separated surface layer was subjected to a low-temperature ashing followed by particle size analysis. As expected, a significant scatter of contact angle values was obtained for the same coal samples. Increasing the amount of mineral matter on the coal surface reduced the value of both advancing and receding contact angles. Also, the scatter of contact angle values increased with the increasing mineral matter content from about 1 to 50 wt%. The results reveal that an important factor in analysis of contact angle variation on coal surfaces is the size of the hydrophilic mineral inclusions. Both the advancing and the receding contact angles decrease with increasing size of the mineral grains. Additionally, the scatter of contact angle values increase with increasing size of the mineral matter grains. Finally, the results of fractal dimension analysis of mineral matter grains distributed over the coal surface indicate that there is no significant effect from the shape of hydrophilic mineral inclusions on both advancing and receding contact angles.

2.
Wound Repair Regen ; 9(3): 213-22, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11472618

RESUMEN

Adults and neonates heal wounds by a repair process associated with scarring in contrast to scar-free wound healing in the fetus. In the present study, human dermal fetal fibroblasts, representing the scarless phenotype, and neonatal human dermal fibroblasts, representing scar-forming phenotype, were examined for potential differences that might influence the wound healing process. Fetal fibroblasts secreted four- to tenfold more latent transforming growth factor-beta1 depending on the cell strains compared. Fetal fibroblasts also produced higher levels of collagen protein and mRNA for most types of collagen (particularly type III) as compared to neonatal cells. Interestingly, mRNA for type V collagen was significantly reduced in fetal cells. Neonatal fibroblasts expressed significantly higher levels of latent transforming growth factor-beta1 binding protein mRNA, in contrast to almost undetectable levels in fetal fibroblasts. By ligand blot analysis, the levels of insulin-like growth factor binding protein-3, a reported mediator of transforming growth factor-beta1 activity, was eightfold higher in neonatal versus fetal fibroblasts. Approximately 20 other mRNAs for various cytokines, matrix molecules and receptors were examined and found to be similar between the two cell types. The phenotypic differences described in this article may represent potentially important mechanisms to explain the differences in the quality of wound repair observed in fetal versus adult/neonatal tissues.


Asunto(s)
Matriz Extracelular/genética , Matriz Extracelular/fisiología , Feto , Fibroblastos/fisiología , Regulación de la Expresión Génica/fisiología , Recién Nacido , Piel/citología , Cicatrización de Heridas/fisiología , Factores de Edad , Línea Celular , Cicatriz/etiología , Cicatriz/fisiopatología , Colágeno/fisiología , Humanos , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/fisiología , ARN Mensajero/fisiología , Factor de Crecimiento Transformador beta/análisis , Factor de Crecimiento Transformador beta/fisiología , Factor de Crecimiento Transformador beta1
3.
Tissue Eng ; 7(3): 267-77, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11429147

RESUMEN

The ability of synthetic or natural scaffolds to support invasion of cells from surrounding tissue is a key parameter for tissue engineering (TE). In this study, the migration of fibroblasts, chondrocytes, and osteoblasts into biodegradable polymer scaffolds was evaluated using a novel, three-dimensional (3-D) transmigration assay. This assay is based on a cell-populated contracted collagen lattice with a biodegradable polymer scaffold implanted at the center of the collagen gel. Cell migration into the scaffolds was assessed both quantitatively and qualitatively following various time lengths in culture using image analysis. Chondrocytes, incorporated within the collagen lattice, migrated into polymer scaffolds, when cultured both statically or in a rotating bioreactor. However, the bioreactor cultures resulted in a significantly greater cell invasion as compared to static cultures. There was a cell density-dependent osteoblast migration from collagen lattice into polymer scaffold, when tested in the transmigration assay. In addition, polymer scaffolds, treated with or without recombinant human platelet-derived growth factor (rh-PDGF-BB) were evaluated for fibroblast migration. The presence of rh-PDGF-BB resulted in significantly greater fibroblast invasion as compared to untreated scaffolds. Our studies suggest that the transmigration model provides a rapid system for testing cell invasion of potential scaffolds for tissue engineering applications.


Asunto(s)
Ingeniería Biomédica/métodos , Técnicas de Cultivo de Célula/métodos , Movimiento Celular , Condrocitos/fisiología , Fibroblastos/fisiología , Osteoblastos/fisiología , Piel/citología , Becaplermina , Biodegradación Ambiental , Reactores Biológicos , Materiales Biocompatibles Revestidos/química , Colágeno/metabolismo , Matriz Extracelular/metabolismo , Geles/química , Humanos , Procesamiento de Imagen Asistido por Computador , Recién Nacido , Factor de Crecimiento Derivado de Plaquetas/farmacología , Polímeros , Porosidad , Proteínas Proto-Oncogénicas c-sis , Proteínas Recombinantes/farmacología , Factores de Tiempo
4.
Anal Biochem ; 291(1): 27-33, 2001 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-11262153

RESUMEN

The currently available methods for the detection of proteases in tissue sections are characterized by limited substrate specificity and low sensitivity and are also cumbersome. We have developed a novel in situ zymography method that uses a synthetic substrate conjugated to a fluorescent tag for detection of proteases in tissue sections. In the presence of active enzyme, the fluorescent tag is cleaved off from the substrate peptide chain resulting in an approximately 100-fold increase in the fluorescent signal. In order to minimize the diffusion of the fluorescent tag, the substrate is incorporated into 1% agarose prior to overlaying onto the tissue section. This method retains the morphological details of the tissue section, is highly sensitive and specific for the designated peptide sequence, and provides information regarding the functional status of the enzyme. Thus, this method could be used for detection and monitoring of enzymatic activity in tissue sections for a variety of applications.


Asunto(s)
Colorantes Fluorescentes/análisis , Metaloproteinasa 1 de la Matriz/análisis , Metaloproteinasa 9 de la Matriz/análisis , Elastasa Pancreática/análisis , Cicatrización de Heridas/fisiología , Heridas Penetrantes/enzimología , Animales , Electroforesis en Gel de Agar/métodos , Endopeptidasas/análisis , Endopeptidasas/metabolismo , Epidermis/enzimología , Metaloproteinasa 1 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Oligopéptidos/metabolismo , Elastasa Pancreática/metabolismo , Sensibilidad y Especificidad , Piel/enzimología , Piel/lesiones , Especificidad por Sustrato/fisiología , Porcinos , Lengua/enzimología , Lengua/lesiones
5.
J Cell Biochem ; 73(3): 408-22, 1999 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-10321840

RESUMEN

Previous studies suggest that there may be species differences in the utilization of cis-elements of the type I collagen genes. The present study was designed to examine this possibility by focusing on two regions of the proalpha1(I) collagen promoter. One is the GC-rich A1 region (-194/168) that modulates transcriptional activity of the mouse promoter. The other contains a glucocorticoid response element (GRE) implicated in negative glucocorticoid regulation of the rat promoter. Unlike mouse A1 probes, probes representing the analogous human (-195/-168) and rat (-193/-179) regions failed to bind nuclear proteins in gel shift assays. Binding assays with mouse A1 probes containing base substitutions indicated that this behavior could be ascribed to five bases in the human, and two in the rat sequences. In addition, the pattern of expression of c-Krox, a protein that alters transcriptional activity via the mouse A1 element, differed in mouse and human tissues. Computer analysis revealed differences in the arrangement of GRE half-sites in human and rat proalpha1(I) collagen promoters. In a region of the human promoter (-700/673) analogous to the rat (-672/-633), there are three half-sites, each separated by two nucleotides, that cooperate in binding of glucocorticoid receptor. There also is a proximal half-site at position -335 of the human promoter that binds glucocorticoid receptor, but it is not present in the rat promoter. This study has defined several species-specific differences in the sequences and nuclear protein binding activity of regions involved in transcriptional activity of the proalpha1(I) collagen promoter. The results suggest that the A1 regions of the human and rat promoters examined here are unlikely to function as regulatory cis-elements, and they provide a framework for investigating the role of GREs in transcriptional regulation. They also suggest that species differences in cis-elements and transcription factors should be taken into consideration when using heterologous systems to study collagen gene regulation.


Asunto(s)
Procolágeno/genética , Regiones Promotoras Genéticas , Especificidad de la Especie , Células 3T3 , Animales , Unión Competitiva , Northern Blotting , Western Blotting , Proteínas Portadoras , Colágeno/metabolismo , Proteínas de Unión al ADN/metabolismo , Electroforesis en Gel de Poliacrilamida , Expresión Génica , Glucocorticoides/metabolismo , Células HeLa , Humanos , Ratones , Ratones Endogámicos BALB C , Modelos Genéticos , Mutagénesis , Ratas , Homología de Secuencia de Ácido Nucleico , Factores de Transcripción/metabolismo
6.
Methods Cell Sci ; 21(1): 47-56, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-10733258

RESUMEN

TGF-beta has been implicated in scarring and tissue fibrosis. Most cells secrete TGF-beta as a high molecular weight, latent complex that must be processed to a lower molecular weight, biologically active form. A number of molecules are involved in this activation step including the mannose 6-phosphate/insulin-like growth factor-II receptor, tissue transglutaminase, thrombospondin, plasmin, and others. Here we describe a rapid macrophage-based system for TGF-beta1 activation, which could be used for screening potential anti-fibrotic agents. The system employs transformed mouse peritoneal macrophages treated with lipopolysaccharide as a cell line capable of activating latent TGF-beta. The activation mechanism in our system involves mannose 6-phosphate/insulin-like growth factor-II receptor and transglutaminase. The activation of latent TGF-beta in this system can be prevented by the addition of mannose-6-phosphate but not mannose-1-phosphate. In addition, transglutaminase inhibitors, antibodies to thrombospondin, insulin-like growth factor-II in the presence of its binding protein IGFBP-2, but not IGFBP-1, suppressed the activation of TGF-beta. Anti-inflammatory molecules, such as hydrocortisone, when added to LPS-treated macrophages, inhibited TGF-beta activation by a mechanism, that may involve downregulation of transglutaminase expression. In summary, this new, rapid and reproducible system allows testing molecules for their ability to inhibit TGF-beta activation, thus providing a screening method for potential anti-scarring molecules.


Asunto(s)
Macrófagos Peritoneales/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Animales , Northern Blotting , Cadaverina/análogos & derivados , Cadaverina/farmacología , Línea Celular , Medios de Cultivo Condicionados , Relación Dosis-Respuesta a Droga , Evaluación Preclínica de Medicamentos/métodos , Humanos , Hidrocortisona/farmacología , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/farmacología , Proteína 2 de Unión a Factor de Crecimiento Similar a la Insulina/farmacología , Factor II del Crecimiento Similar a la Insulina/antagonistas & inhibidores , Factor II del Crecimiento Similar a la Insulina/farmacología , Lipopolisacáridos , Macrófagos Peritoneales/efectos de los fármacos , Manosafosfatos/farmacología , Ratones , Reacción en Cadena de la Polimerasa , Factor de Crecimiento Transformador beta/análisis , Factor de Crecimiento Transformador beta/antagonistas & inhibidores , Transglutaminasas/antagonistas & inhibidores , Transglutaminasas/metabolismo , Regulación hacia Arriba/efectos de los fármacos
7.
Arch Biochem Biophys ; 357(1): 101-10, 1998 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-9721188

RESUMEN

Insulin-like growth factors (IGFs) I and II stimulate growth and expression of specific genes through binding to cell membrane receptors. IGF binding proteins also bind IGF-I with higher affinity than the receptor. They are found in the circulation and tissues and can modulate IGF actions. Human IGFBP-1 is phosphorylated on serine residues, which increases its affinity for IGF-I. An acidic, presumably phosphorylated, form of human IGFBP-1 inhibits IGF-I-stimulated DNA synthesis in cultured cells, while a less acidic, unphosphorylated form potentiates this function. Phosphorylation of human IGFBP-3, however, does not affect its affinity for IGF-I. Previously we found that multiple forms of rat IGFBP-1 are obtained by anion-exchange chromatography, raising the possibility that it also is phosphorylated, which led us to examine its properties. Phosphopeptide analysis of 32P-labeled, immunoprecipitated rat IGFBP-1 synthesized by H-4-II-EC3 rat hepatoma cells indicated that it is phosphorylated on two sites that were deduced to be ser107 and ser132 in the central nonconserved domain. Dephosphorylation of purified phosphorylated rat IGFBP-1 did not affect its affinity for IGF-I or its specific binding activity, and the dephosphorylated form inhibited DNA synthesis in 3T3 cells. Incubation of cells labeled with radioactive proline in the presence of monensin and brefeldin A, which inhibit secretion at different sites, led to intracellular accumulation of the least phosphorylated form of rat IGFBP-1, but prevented further phosphorylation. The results suggested that phosphorylation occurs at two sites in cells, the cis-Golgi and the trans-Golgi network. In summary, these studies have shown that rat IGFBP-1 is phosphorylated on two sites by reactions that occur in different secretory organelles and that similar to human IGFBP-3, but unlike human IGFBP-1, phosphorylation does not affect its affinity for IGF-I.


Asunto(s)
Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/fisiología , Células 3T3 , Secuencia de Aminoácidos , Animales , Sitios de Unión , Carcinoma Hepatocelular , Cromatografía por Intercambio Iónico , ADN/antagonistas & inhibidores , ADN/biosíntesis , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/aislamiento & purificación , Factor I del Crecimiento Similar a la Insulina/metabolismo , Ratones , Datos de Secuencia Molecular , Mapeo Peptídico , Fosfopéptidos/metabolismo , Fosforilación , Unión Proteica , Ratas , Fracciones Subcelulares/metabolismo , Especificidad por Sustrato , Células Tumorales Cultivadas
8.
Int J Biochem Cell Biol ; 29(1): 241-50, 1997 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-9076959

RESUMEN

One of the major differences between fetal and adult wound repair is the unique ability of fetal wounds to heal without scarring. Since scar formation is a function of extracellular matrix deposition, the regulation of this component is fundamental in tissue remodeling. In this study, we have characterized the differences in the secretion of matrix-degrading proteases, namely urokinase plasminogen activator and gelatinase A and B, from fetal and neonatal fibroblasts. In addition, we examined the modulation of these protease levels by growth factors known to be important in wound repair. The results indicate that the secretion of these proteases differ significantly between the two cell types. The levels of urokinase plasminogen activator and its inhibitor were notably higher in media conditioned by neonatal fibroblasts in comparison to fetal samples. In contrast, the basal level of gelatinase A was comparable in both cell types, whilst the level of gelatinase B was elevated in the fetal fibroblasts. Transforming growth factor-beta 1 reduced the level of urokinase plasminogen activator and stimulated the secretion of plasminogen activator inhibitor-1 and progelatinase B in both neonatal and fetal fibroblasts. However, only progelatinase A and an activated form of gelatinase B were significantly elevated in fetal fibroblasts. In contrast, platelet-derived growth factor stimulated urokinase plasminogen activator, its inhibitor and both gelatinase A and B, an effect which was more apparent in fetal fibroblasts. This difference in protease regulation may be reflected in the differing rate and quality of tissue remodeling observed during adult vs fetal wound repair.


Asunto(s)
Endopeptidasas/metabolismo , Feto/enzimología , Fibroblastos/efectos de los fármacos , Fibroblastos/enzimología , Sustancias de Crecimiento/farmacología , Adulto , Cicatriz/enzimología , Cicatriz/etiología , Colagenasas/metabolismo , Femenino , Gelatinasas/metabolismo , Humanos , Recién Nacido , Metaloproteinasa 2 de la Matriz , Metaloproteinasa 9 de la Matriz , Metaloendopeptidasas/metabolismo , Inhibidor 1 de Activador Plasminogénico/metabolismo , Factor de Crecimiento Derivado de Plaquetas/farmacología , Embarazo , Lesiones Prenatales , Factor de Crecimiento Transformador beta/farmacología , Activador de Plasminógeno de Tipo Uroquinasa/metabolismo , Cicatrización de Heridas/efectos de los fármacos , Cicatrización de Heridas/fisiología
9.
Arch Biochem Biophys ; 336(1): 86-96, 1996 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-8951038

RESUMEN

The precise physiological role of alkaline phosphatase is unknown, although evidence suggests it is involved in bone mineralization. Previous studies showed that serum and bone alkaline phosphatase activity is decreased during vitamin C deficiency. Some effects of scurvy, such as inhibition of collagen synthesis, are related to weight loss and subsequent induction of insulin-like growth factor binding proteins and they can be duplicated in fasted guinea pigs receiving vitamin C. We found that decreased alkaline phosphatase activity in bone and serum during scurvy was not completely due to the "fasting effect" and that the decrease in serum was due to loss of bone isoenzyme activity. There also was a decrease in immunoreactive enzyme protein and alkaline phosphatase mRNA concentrations in bone of scorbutic animals, indicating that synthesis of the enzyme was inhibited. Sialylation and addition of the glycosylphosphatidylinositol anchor to the enzyme in bone tissue were not affected by scurvy. The concentration of mRNA for osteocalcin, a bone-specific marker, also fell during scurvy and to a much greater extent than either alkaline phosphatase or type I collagen mRNAs, while osteopontin mRNA concentrations increased. These results differ from the reported role of ascorbic acid on the pattern of expression of these proteins during differentiation of osteoblasts in culture. The decreased expression of collagen, alkaline phosphatase, and osteocalcin could explain the defects in bone caused by scurvy.


Asunto(s)
Fosfatasa Alcalina/metabolismo , Huesos/enzimología , Escorbuto/enzimología , Animales , Colágeno/genética , Femenino , Expresión Génica , Glicosilación , Cobayas , Isoenzimas/metabolismo , Hígado/enzimología , Peso Molecular , Osteocalcina/genética , Osteopontina , Procesamiento Proteico-Postraduccional , ARN Mensajero/genética , Escorbuto/genética , Sialoglicoproteínas/genética
10.
Arch Biochem Biophys ; 325(2): 295-303, 1996 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-8561510

RESUMEN

The regulation of expression of hepatic iron-related proteins was examined during iron deficiency caused by scurvy in guinea pigs. Previous studies showed that some effects of scurvy, such as suppression of collagen gene expression, result from events associated with weight loss. During the initial phase of scurvy when vitamin C is depleted but animals grow normally, serum iron levels decreased to 50% of normal. During the second phase of scurvy when animals lose weight, there was a further decrease in iron levels to 10-15% of normal. Serum transferrin levels increased during scurvy, but this increase was related neither to the rate of weight loss nor to hepatic transferrin mRNA expression, which decreased. Serum ferritin levels of diminished early in scurvy with a preferential loss of the L subunit. In liver, however, both ferritin animals gaining weight. Ferritin gene expression during vitamin C deficiency was correlated with serum ferritin levels in that the level of mRNA for the H subunit remained relatively constant while that of the L subunit decreased early. Transferrin receptor mRNA expression in liver was induced as soon as iron levels decreased early in scurvy, which is similar to results reported for iron-depleted cultured cells. In contrast to results in cell culture, expression of iron regulatory protein 1 mRNA was decreased to approximately 50% of normal early in scurvy with a concomitant decrease in hepatic cytosolic aconitase activity. Our data indicate that iron deficiency occurs early during vitamin C deficiency and leads to changes in expression of iron-related proteins that differ in some aspects from regulation by iron in cell culture. Other events associated with weight loss in late scurvy may play a further role in this regulation.


Asunto(s)
Deficiencias de Hierro , Proteínas/genética , Escorbuto/genética , Aconitato Hidratasa/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Citosol/enzimología , ADN Complementario/genética , Ferritinas/química , Ferritinas/genética , Regulación de la Expresión Génica , Cobayas , Hierro/sangre , Proteínas Reguladoras del Hierro , Hígado/metabolismo , Datos de Secuencia Molecular , Sondas de Oligonucleótidos/genética , Conformación Proteica , Proteínas/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/sangre , Proteínas de Unión al ARN/genética , Receptores de Transferrina/genética , Escorbuto/complicaciones , Escorbuto/metabolismo , Transferrina/genética , Transferrina/metabolismo , Pérdida de Peso/fisiología
11.
Wound Repair Regen ; 3(2): 192-203, 1995.
Artículo en Inglés | MEDLINE | ID: mdl-17173648

RESUMEN

Poor wound healing during vitamin C deficiency is thought to be due to decreased hydroxylation of proline residues in collagen. In non-repair connective tissues of guinea pigs, however, procollagen gene expression is not decreased until weight loss occurs during the third and fourth weeks of scurvy (phase II) with only a moderate decrease in proline hydroxylation. Decreased procollagen gene expression is related to the induction of insulin-like growth factor binding proteins 1 and 2 that inhibit insulin-like growth factor-I action. We examined wound healing and granulation tissue formation during phase I of vitamin C deficiency. Synthetic sponges were implanted on day 7 of vitamin C deficiency and analyzed at 6 and 10 days after surgery, when there was no weight loss or induction of insulin-like growth factor binding proteins. Healing of incisions was almost complete at 10 days after surgery in normal controls but not in scorbutic animals. The area around the incision and implant exhibited excessive angiogenesis and hemorrhaging of vessels in the scorbutic animals at 6 and 10 days after surgery. At 10 days after surgery, collagen synthesis in the implants of scorbutic guinea pigs was 36% lower than control values, with a normal extent of proline hydroxylation. Concentrations of messenger RNAs for types I and III procollagens were slightly increased by scurvy at 6 days after surgery but were decreased by 26% and 40%, respectively, at 10 days. Fibronectin mRNA levels were unaffected by scurvy at both time points. Our results suggest that poor wound healing in phase I of scurvy may be related to defective interstitial procollagen gene expression and defective blood vessel formation, but it does not involve inhibition of proline hydroxylation or induction of insulin-like growth factor binding proteins. mRNA for insulin-like growth factor-II, transforming growth factor-beta(1), and transforming growth factor-beta(2) were significantly expressed in implants, but their patterns of expression did not correlate with changes in procollagen gene expression.

12.
Endocrine ; 3(12): 889-97, 1995 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21153217

RESUMEN

Fasting (with vitamin C-supplementation) and vitamin C-deficiency in guinea-pigs are associated with decreased collagen gene expression in connective tissues. Recently we presented evidence that circulating insulin-like growth factor binding protein (IGFBP)-1 and-2 that are induced during both nutritional deficiencies may be responsible for this inhibition by interfering with IGF-I action. The present objective was to determine whether circulating IGFBPs are accumulated in bone, skin and cartilage during fasting, which would support an endocrine role for them. IGFBP-1 mRNA was not detected in any of the connective tissues. The protein, as measured by ligand blotting, was not present in tissues of normal animals but accumulated early during fasting in all of the tissues. Bone and cartilage from normal animals contained IGFBP-2 and its mRNA, but only in bone did their levels increase during fasting. IGFBP-3 mRNA was not detected in connective tissues from normal or fasted guinea-pigs. Little or no IGFBP-3 was detected in normal tissue extracts, but protein accumulated during fasting and presumably was derived from the circulation. IGF-I and-II mRNAs were expressed in bone and cartilage but in skin, only IGF-II mRNA was detected. Affinity cross-linking revealed that in skin, IGFBP-3 contained relatively few unoccupied IGF-I binding sites compared to IGFBP-1 while in bone and cartilage, only IGFBP-1 contained unoccupied binding sites. IGFBP-1, acting by endocrine action, is probably the major factor responsible for inhibition of IGF-I-dependent collagen gene expression during fasting.

13.
Endocrinology ; 134(3): 1329-39, 1994 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-7509738

RESUMEN

Acutely scorbutic and fasted (vitamin C-supplemented) guinea pigs exhibit decreased collagen gene expression associated with weight loss. We recently demonstrated that circulating insulin-like growth factor-binding protein-1 and -2 (IGFBP-1 and -2) are induced in these deficiencies, and that removal of IGFBP-1 and -2 from serum of such animals by specific antibodies reverses inhibition of cellular IGF-I-dependent functions, including collagen and DNA synthesis. Here we investigated the kinetics of induction of IGFBP-1 and -2 relative to suppression of collagen gene expression. Guinea pigs were fasted for 10-96 h, with 3-24% weight loss, or received an ascorbate-free diet for up to 4 weeks, with 5-28% weight loss during the third and fourth weeks (phase II of scurvy). In both deficiencies, there was noncoordinate regulation of collagen mRNA expression in tissues. Type I collagen mRNA concentrations in skin decreased rapidly after 5-10% weight loss and reached about 10% of normal levels, whereas in bone, there was a later, and not as extensive, decrease. The concentration of cartilage type II collagen mRNA decreased rapidly initially, but then remained at 40-50% of normal. Circulating IGF-I concentrations remained normal during the period when collagen gene expression was initially suppressed, although there was a later decrease. In contrast, mRNAs for IGFBP-1 and -2 and the circulating proteins were induced before or concomitantly with the suppression of collagen gene expression. The ability of fasted or scorbutic guinea pig sera to inhibit IGF-I action in cells increased in parallel with IGFBP activity ([125I]IGF-I binding), which, in turn, mainly reflected the concentration of IGFBP-1 in sera. Serum insulin may be the primary regulator of the IGFBPs. Its levels were decreased to 10-13% of normal when weight loss commenced, whereas cortisol levels, although increased, did not correlate with the induction of IGFBPs. The overall results taken together with our recent findings from cell culture experiments are compatible with circulating IGFBP-1 and -2 acting as inhibitors of collagen gene expression by blocking IGF-I action during fasting and phase II of vitamin C deficiency.


Asunto(s)
Deficiencia de Ácido Ascórbico/metabolismo , Proteínas Portadoras/fisiología , Colágeno/genética , Regulación de la Expresión Génica , Somatomedinas/metabolismo , Animales , Secuencia de Bases , Glucemia/análisis , Proteínas Portadoras/genética , Ayuno , Cobayas , Hidrocortisona/sangre , Insulina/sangre , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina , Proteína 2 de Unión a Factor de Crecimiento Similar a la Insulina , Factor I del Crecimiento Similar a la Insulina/genética , Datos de Secuencia Molecular , ARN Mensajero/análisis , Pérdida de Peso
14.
Growth Factors ; 10(4): 229-41, 1994.
Artículo en Inglés | MEDLINE | ID: mdl-7528515

RESUMEN

Collagen gene expression and proteoglycan synthesis are decreased in vitamin C-deficient guinea pigs losing weight and in fasted guinea pigs receiving ascorbate. Sera from such guinea pigs contain an insulin-like growth factor (IGF)-I-reversible inhibitor of collagen, proteoglycan and DNA synthesis and elevated levels of 29 and 35-kDa IGF binding proteins (IGFBPs). We now have identified the induced proteins as IGFBPs 1 and 2 and investigated their role as inhibitors. Guinea pig sera were treated with antibodies to IGFBPs 1 and 2 and antibody-IGFBP complexes were removed by passage through a Protein A-Sepharose column. Inhibitor content of fasted and scorbutic sera, and Protein A pass-through fractions derived from them, was assessed by their level of stimulation of DNA and collagen synthesis in 3T3 cells, compared to analogously treated normal guinea pig serum. Removal of IGFBP-1 from scorbutic serum reversed inhibition of collagen and DNA synthesis by more than half but removal of IGFBP-2 was less effective. Removal of both IGFBPs reversed inhibition almost completely. Similar results were obtained with fasted guinea pig serum. Conversely, purified rat IGFBPs 1 and 2 inhibited DNA and collagen synthesis in cells cultured in normal guinea pig serum or IGF-I-stimulated DNA synthesis, with IGFBP-1 being more potent. Thus, IGFBP-1 and, to a lesser extent IGFBP-2, cause inhibition of IGF-I action by sera from fasted and scorbutic guinea pigs and may inhibit collagen gene expression in vivo.


Asunto(s)
Proteínas Portadoras/farmacología , Factor I del Crecimiento Similar a la Insulina/antagonistas & inhibidores , Células 3T3 , Animales , Deficiencia de Ácido Ascórbico/sangre , Proteínas Portadoras/sangre , Proteínas Portadoras/aislamiento & purificación , Colágeno/biosíntesis , Colágeno/genética , ADN/biosíntesis , Ayuno/sangre , Expresión Génica/efectos de los fármacos , Cobayas , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina , Proteína 2 de Unión a Factor de Crecimiento Similar a la Insulina , Factor I del Crecimiento Similar a la Insulina/farmacología , Ratones , Proteoglicanos/biosíntesis , Ratas , Somatomedinas/metabolismo
15.
J Cell Physiol ; 153(3): 450-9, 1992 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-1447307

RESUMEN

Regulation of the synthesis of procollagen and other extracellular matrix components was examined in human skin fibroblasts obtained from donors of various ages, from fetal to 80 years old (in vivo aged), and in fetal fibroblasts at varying passage levels (in vitro aged). Growth rates and saturation densities of fibroblasts decreased with increasing age of the donor and after passage 20 of fetal fibroblasts. The rates of collagen and proteoglycan synthesis also decreased during both types of aging to about 10-25% of the rate in early passage fetal fibroblasts, whereas the synthesis of total noncollagenous proteins was not greatly affected. Decreased collagen synthesis in both types of aging was correlated with lower steady-state levels of mRNAs for the two subunits of type I procollagen mRNA, although their regulation was not coordinate. Type III collagen mRNA levels also declined in both types of aging. The concentration of fibronectin mRNA also decreased during in vitro aging but more rapidly than the collagen mRNAs, whereas in fibroblasts from 51-80-year-old donors, it was similar to or higher than in early passage fetal fibroblasts. This study suggests that the decreased synthesis of procollagen and proteoglycans in in vivo aged fibroblasts represents changes that are responsible for intrinsic degenerative changes that occur in human skin during aging. Furthermore, although in vitro and in vivo aging were similar in many respects, they were not equivalent, as evidenced by the differences in regulation of fibronectin expression.


Asunto(s)
Proteínas de la Matriz Extracelular/metabolismo , Piel/metabolismo , División Celular , Células Cultivadas , Senescencia Celular , Colágeno/biosíntesis , Fibroblastos/metabolismo , Fibroblastos/fisiología , Fibronectinas/genética , Humanos , Proteoglicanos/biosíntesis , Proteoglicanos/genética , ARN Mensajero/metabolismo , Piel/citología
16.
Biochem Biophys Res Commun ; 188(2): 780-5, 1992 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-1280122

RESUMEN

4-Nitroquinoline-1-oxide-transformed Syrian hamster embryo fibroblasts (NQT-SHE) synthesize the pro alpha 2 chain but not the pro alpha 1 subunit of type I procollagen, and they contain little pro alpha 1(I)mRNA. This study shows that there was no accumulation of pro alpha 1(I) poly(A)+ mRNA in NQT-SHE fibroblasts. BHK cells, a normal established line of hamster fibroblasts that synthesized collagen at approximately the same rate as NQT-SHE fibroblasts, nevertheless produced both subunits of type I collagen and contained pro alpha 1(I)mRNA. Run-off transcription assays with isolated nuclei showed that both the pro alpha 1(I) and pro alpha 2(I) genes were transcribed at about the same rate in NQT-SHE cells as well as in the normal BHK cells. These results suggest that a post-transcriptional defect, probably resulting from transformation, prevents the accumulation of pro alpha 1(I)mRNA in NQT-SHE cells.


Asunto(s)
Procolágeno/biosíntesis , Procolágeno/genética , Procesamiento Postranscripcional del ARN , Transcripción Genética , Animales , Northern Blotting , Línea Celular Transformada , Núcleo Celular/metabolismo , Cricetinae , Electroforesis en Gel de Poliacrilamida , Embrión de Mamíferos , Fibroblastos/metabolismo , Riñón , Mesocricetus , Peso Molecular , Poli A/aislamiento & purificación , Poli A/metabolismo , Procolágeno/aislamiento & purificación , ARN/aislamiento & purificación , ARN/metabolismo , ARN Mensajero/metabolismo
17.
Pol Tyg Lek ; 47(27-28): 579-82, 1992.
Artículo en Polaco | MEDLINE | ID: mdl-1488331

RESUMEN

Insulinemia in patients with essential hypertension and normal glucose tolerance was assessed. The study involved 25 patients divided into subgroups according body weight and 9 of control subjects. It was found, that hyperinsulinemia seen in hypertensive patients seems to be associated with obesity. Moreover, hyperinsulinemia does not depend primarily on hypersecretion of insulin but may reflect resistance to insulin and ab normal metabolism in the liver.


Asunto(s)
Glucemia/análisis , Péptido C/sangre , Hipertensión/sangre , Insulina/sangre , Obesidad/sangre , Adulto , Peso Corporal/fisiología , Femenino , Prueba de Tolerancia a la Glucosa , Humanos , Hipertensión/complicaciones , Masculino , Persona de Mediana Edad , Obesidad/complicaciones
18.
Pol Tyg Lek ; 47(1-2): 28-30, 1992.
Artículo en Polaco | MEDLINE | ID: mdl-1409037

RESUMEN

In 110 diabetics type I and type II and in 30 control subjects the total serum activity of NAG as well as of its isoenzymatic forms A and B was determined. In cases with diabetic nephropathy the GFR and serum creatinine was also analysed. It was found that NAG activity is correlated to the degree of clinical symptoms of diabetic vascular changes. Therefore it could be suggested that NAG plays a role in development of microangiopathy. NAG determination may also serve as an index differentiating the diabetic microangiopathy from other forms of microvessels.


Asunto(s)
Acetilglucosaminidasa/sangre , Diabetes Mellitus Tipo 1/enzimología , Diabetes Mellitus Tipo 2/enzimología , Retinopatía Diabética/enzimología , Isoenzimas/sangre , Adulto , Anciano , Diabetes Mellitus Tipo 1/complicaciones , Diabetes Mellitus Tipo 2/complicaciones , Nefropatías Diabéticas/enzimología , Retinopatía Diabética/etiología , Activación Enzimática/fisiología , Femenino , Humanos , Masculino , Microcirculación/enzimología , Persona de Mediana Edad , Proteinuria/enzimología
19.
Horm Metab Res ; 23(5): 236-8, 1991 May.
Artículo en Inglés | MEDLINE | ID: mdl-1874483

RESUMEN

The aim of the present study was the observation of the frequency of antithyroid autoantibodies in the population in low endemic goitre area after mass iodine prophylaxis after the Chernobyl catastrophe and the estimation of TSH and thyroid hormones secretion in this population. On the basis of the investigations carried out we could conclude that the frequency of antithyroid autoantibodies in the population with confirmed endemic goitre is comparable to the frequency of antithyroid autoantibodies in the healthy population. ATA occurrence in children after iodine prophylaxis could confirm the hypothesis that thyroglobulin immunity is higher after iodine intake. The lower T3 concentration observed in the group with antithyroid autoantibodies suggests that autoantibodies may be involved in the thyroid hormones synthesis or peripheral conversion of thyroid hormones.


Asunto(s)
Accidentes de Trabajo , Autoanticuerpos/inmunología , Bocio Endémico/prevención & control , Yodo/uso terapéutico , Glándula Tiroides/inmunología , Adolescente , Adulto , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Reactores Nucleares , Tiroxina/sangre , Triyodotironina/sangre , Ucrania
20.
Endokrynol Pol ; 42(2): 215-34, 1991.
Artículo en Polaco | MEDLINE | ID: mdl-1364474

RESUMEN

The results of the investigations of radioactive contamination after the Chernobyl catastrophe and subsequent iodine prophylaxis on the thyroid gland function and morphology in Northeast Poland. The aim of the study was to determine whether kalium iodine in one dose during radioactive contamination in Poland limited the radioactive dose in the thyroid gland and if significant disadvantageous side-effects in the intrathyroid and extrathyroid occurred. Additionally during the studies we tried to determine if radioactive iodine contamination which occurred in the region of the Medical Academy in Bialystok caused an increase in thyroid disease. It is interesting to note the different results obtained after radioactive contamination with the results from the investigations in this same territory in 1983-1985. In 1983-1985, before the Chernobyl catastrophe, 6,921 persons in Northeast Poland were investigated. In 1986-1988, immediately after the disaster 4,010 persons were investigated. The main study according to grant No MZ-XVII was carried out in three provinces: Bialystok, Suwalki and Olsztyn. In this investigation 10,011 persons born before April 26, 1986 and after January 1, 1936 participated, 5,789 townspeople and 4,222 villagers, 3,987 children up to 16 years of age it the time of the disaster 1,973 boys and 2,009 girls; 6,024 adults 2,509 men and 3,516 women were drawn from a register. Committed doses to the thyroid in the investigated region were one of the highest in Poland and depended on age group and were depended on time of prophylaxis non proportional. Iodine prophylaxis was provided mainly with one dose of Lugol solution about 90%, 95% children and 30% adults took iodine. The majority of the population (53.3%-74%) were given iodine in April. From May 1st to 5th 23.0-43.4% received iodine, but after May 5th very few persons. Iodine was well tolerated, but Lugol Solution was better tolerated than other kinds of iodine. Only 241 (4.4%) cases had side effects, mainly vomiting (143), symptoms such as stomach ache, diarrhea, dyspnoe, skinrash etc. in lesser numbers. 12% (29 persons) were seen by a physician. In the investigated population were 200 pregnant women aged 19-40 years of which the majority (177) delivered full term healthy babies. Only 1 interrupted pregnancy and 7 had spontaneous abortion. Changes in the thyroid were noticed by 187 persons (2.3%-11.7%) most of which were enlargement of the thyroid, but only a few were confirmed by a physician. In the studied population from 1989 to 1990 over 30% of the population had struma.(ABSTRACT TRUNCATED AT 400 WORDS)


Asunto(s)
Contaminantes Radiactivos del Aire/efectos adversos , Bocio/epidemiología , Yoduros/uso terapéutico , Centrales Eléctricas , Liberación de Radiactividad Peligrosa , Enfermedades de la Tiroides/prevención & control , Adolescente , Adulto , Niño , Femenino , Humanos , Masculino , Polonia/epidemiología , Embarazo , Resultado del Embarazo , Enfermedades de la Tiroides/etiología , Ucrania
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...