RESUMO
Esophagectomy causes postprandial symptoms associated with an exaggerated postprandial gut hormone response. This study aimed to compare the gastrointestinal transit time of patients 1 year after esophagectomy with unoperated controls, including its relation to satiety gut hormone release. In this cross-sectional study, consecutive, disease-free patients after esophagectomy with pyloroplasty were compared with unoperated control subjects to assess gastric emptying (GE) and cecal arrival time (CAT). Serial plasma samples were collected before, and for 300 minutes after, a mixed-meal challenge. Body composition was assessed, and symptom scores were calculated. Eleven patients 1 year post-esophagectomy (age: 62.6 ± 9.8, male: 82%) did not show a significantly different GE pattern compared with 10 control subjects (P = 0.245). Rather, patients could be categorized bimodally as exhibiting either rapid or slow GE relative to controls. Those with rapid GE trended toward a higher postprandial symptom burden (P = 0.084) without higher postprandial glucagon-like peptide-1 (GLP-1) secretion (P = 0.931). CAT was significantly shorter after esophagectomy (P = 0.043) but was not significantly associated with GE, GLP-1 secretion, or symptom burden. Neither early nutrient delivery to the proximal small intestine nor to the colon explains the exaggerated postprandial GLP-1 response after esophagectomy. GE varies significantly in these patients despite consistent pyloric management.
Assuntos
Esofagectomia , Esvaziamento Gástrico , Estudos Transversais , Peptídeo 1 Semelhante ao Glucagon , Humanos , Masculino , Período Pós-PrandialRESUMO
BACKGROUND: Oesophagectomy is associated with reduced appetite, weight loss and postprandial hypoglycaemia, the pathophysiological basis of which remains largely unexplored. This study aimed to investigate changes in enteroendocrine function after oesophagectomy. METHODS: In this prospective study, 12 consecutive patients undergoing oesophagectomy were studied before and 10 days, 6, 12 and 52 weeks after surgery. Serial plasma total fasting ghrelin, and glucagon-like peptide 1 (GLP-1), insulin and glucose release following a standard 400-kcal mixed-meal stimulus were determined. CT body composition and anthropometry were assessed, and symptom scores calculated using European Organisation for Research and Treatment of Cancer (EORTC) questionnaires. RESULTS: At 1 year, two of the 12 patients exhibited postprandial hypoglycaemia, with reductions in bodyweight (mean(s.e.m.) 17·1(3·2) per cent, P < 0·001), fat mass (21.5(2.5) kg versus 25.5(2.4) kg before surgery; P = 0·014), lean body mass (51.5(2.2) versus 54.0(1.8) kg respectively; P = 0·003) and insulin resistance (HOMA-IR: 0.84(0.17) versus 1.16(0.20); P = 0·022). Mean(s.e.m.) fasting ghrelin levels decreased from postoperative day 10, but had recovered by 1 year (preoperative: 621·5(71·7) pg/ml; 10 days: 415·1(59·80) pg/ml; 6 weeks: 309·0(42·0) pg/ml; 12 weeks: 415·8(52·1) pg/ml; 52 weeks: 547·4(83·2) pg/ml; P < 0·001) and did not predict weight loss (P = 0·198). Postprandial insulin increased progressively at 10 days, 6, 12 and 52 weeks (mean(s.e.m.) insulin AUC0-30 min : fold change 1·7(0·4), 2·0(0·4), 3·5(0·7) and 4·0(0·8) respectively; P = 0·001). Postprandial GLP-1 concentration increased from day 10 after surgery (P < 0·001), with a 3·3(1·8)-fold increase at 1 year (P < 0·001). Peak GLP-1 level was inversely associated with the postprandial glucose nadir (P = 0·041) and symptomatic neuroglycopenia (Sigstad score, P = 0·017, R2 = 0·45). GLP-1 AUC predicted loss of weight (P = 0·008, R2 = 0·52) and fat mass (P = 0·010, R2 = 0·64) at 1 year. CONCLUSION: Altered enteroendocrine physiology is associated with early satiety, weight loss and postprandial hypoglycaemia after oesophagectomy.
Assuntos
Esofagectomia , Hormônios Gastrointestinais/sangue , Hipoglicemia/etiologia , Complicações Pós-Operatórias/etiologia , Adulto , Idoso , Biomarcadores/sangue , Glicemia/metabolismo , Composição Corporal , Feminino , Seguimentos , Grelina/sangue , Peptídeo 1 Semelhante ao Glucagon/sangue , Humanos , Hipoglicemia/sangue , Hipoglicemia/diagnóstico , Hipoglicemia/fisiopatologia , Insulina/sangue , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , Complicações Pós-Operatórias/sangue , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/fisiopatologia , Período Pós-Prandial , Estudos Prospectivos , Resposta de Saciedade , Redução de PesoRESUMO
Obesity is associated with significant complications and healthcare costs, but our ability to treat obesity has been limited by our understanding of its pathogenesis. We surveyed diabetologists and obesity related health care professionals asking them which organ they believed to be responsible for the pathogenesis of obesity. Participants favoured a central nervous system (CNS) aetiology. The response echoes evidence from genome wide association studies identifying a link between obesity and CNS loci. Our most successful obesity therapies involve the manipulation of subcortical area of the brain involved in energy balance. Future success in the management of obesity will be determined by our ability to define the pathogenesis of the disease in individual cases, moving from a one-size-fits-all, to more focused interventions.
RESUMO
AIM: The colonic mucus gel layer is composed of mucins that may be sulphated or sialyated. Sulphated mucins predominate in health while in ulcerative colitis (UC) sulphation is reduced. These differences result directly from inflammatory events. It may also be hypothesized that they arise in part from alterations in the colonic microbiota, particularly changes in the burden of sulphated mucin-metabolizing species, such as Desulfovibrio (DSV) bacteria. The aim of this study was to correlate colonic mucin chemotypes and inflammatory scores in health and UC and relate these changes to changes in the colonization of colonic crypts by DSV. METHOD: Paired colonic biopsies from 34 healthy controls (HC) and 19 patients with active UC were collected for the purpose of parallel histological and microbiological assessment. High-iron diamine and Alcian blue staining and haematoxylin and eosin of mucosal biopsy specimens were used to assess histological changes within the clinical spectrum of UC. Quantitative real-time polymerase chain reaction analysis was employed to determine the total and DSV copy number within the colonic crypts. RESULTS: Compared with HC, the mucin chemotype in UC was less sulphated and inversely correlated with the degree of mucosal inflammation. A weak but significant negative correlation was found between the abundance of sulphated mucins and DSV burden. CONCLUSION: Mucin composition strongly correlates with the degree of mucosal inflammation, and to a lesser extent with DSV burden. These data suggest that mucin chemotype and DSV burden are linked phenomena and highlight the need to consider changes in mucin chemotype in the setting of microbial dysbiosis occurring within the colitic colon. What does this paper add to the literature? Decreased sulphation of mucins has been associated with inflammation in ulcerative colitis. Currently there are few data describing the relationship between microbial species and changes in mucin chemotype. This study validates previous findings and presents evidence of changes in mucin chemotype occurring in tandem with coherent changes in the microbiota within crypt niches.
Assuntos
Colite Ulcerativa/metabolismo , Colo/química , DNA Bacteriano/análise , Desulfovibrio/isolamento & purificação , Mucosa Intestinal/química , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Estudos de Casos e Controles , Colite Ulcerativa/microbiologia , Colite Ulcerativa/patologia , Colo/microbiologia , Colo/patologia , Feminino , Humanos , Mucosa Intestinal/microbiologia , Mucosa Intestinal/patologia , Masculino , Pessoa de Meia-Idade , Mucinas/análise , Sialomucinas/análise , Adulto JovemRESUMO
PURPOSE: Oxidative stress is implicit in the pathological changes associated with glaucoma. The purpose of this study was to compare levels of oxidative stress in glial fibrillary acid-negative protein (GFAP) lamina cribrosa (LC) cells obtained from the optic nerve head (ONH) region of 5 normal (NLC) and 4 glaucomatous (GLC) human donor eyes and to also examine mitochondrial function and calcium homeostasis in this region of the ONH. METHODS: Intracellular reactive oxygen species (ROS) production was examined by a thiobarbituric acid reactive substances (TBARS) assay which measures malondialdehyde (MDA), a naturally occurring product of lipid peroxidation and is used as an indicator of oxidative stress. Mitochondrial membrane potential (MMP) and intracellular calcium ([Ca(2+)](i)) levels were evaluated by flow cytometry using the JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetrabenzimidazolecarbocyanine iodide) and fluo-4/AM probes respectively. Anti-oxidant and Ca(2+) transport system gene and protein expression were determined by real time polymerase chain reaction (RT-PCR) using gene-specific primer/probe sets and western immunoblotting, respectively. RESULTS: Intracellular ROS production was increased in GLC compared to NLC (27.19 ± 7.05 µM MDA versus 14.59 ± 0.82 µM MDA, p < 0.05). Expression of the anti-oxidants Aldo-keto reductase family 1 member C1 (AKR1C1) and Glutamate cysteine ligase catalytic subunit (GCLC) were significantly lower in GLC (p = 0.02) compared to NLC control. MMP was lower in GLC (57.5 ± 6.8%) compared to NLC (41.8 ± 5.3%). [Ca(2+)](i) levels were found to be higher (p < 0.001) in GLC cells compared to NLC. Expression of the plasma membrane Ca(2+)/ATPase (PMCA) and the sodium-calcium (NCX) exchangers were lower, while intracellular sarco-endoplasmic reticulum Ca(2+)/ATPase 3 (SERCA) expression was significantly higher in GLC compared to NLC. Subjection of NLC cells to oxidative stress (200 µM H(2)0(2)) reduced expression of Na(+)/Ca2(+) exchanger 1 (NCX 1), plasma membrane Ca2+ ATPase 1 (PMCA 1), and PMCA 4 as determined by RT-PCR. CONCLUSIONS: Our data finds evidence of oxidative stress, mitochondrial dysfunction and impaired calcium extrusion in GLC cells compared to NLC cells and suggests their importance in the pathological changes occurring at the ONH in glaucoma. Future therapies may target reducing oxidative stress and / or [Ca(2+)](i).
Assuntos
Astrócitos/metabolismo , Cálcio/metabolismo , Lâmina Limitante Posterior/metabolismo , Glaucoma/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Mitocôndrias/metabolismo , Disco Óptico/metabolismo , 20-Hidroxiesteroide Desidrogenases/genética , 20-Hidroxiesteroide Desidrogenases/metabolismo , Idoso , Idoso de 80 Anos ou mais , Astrócitos/citologia , Western Blotting , Estudos de Casos e Controles , Técnicas de Cultura de Células , Lâmina Limitante Posterior/citologia , Lâmina Limitante Posterior/patologia , Citometria de Fluxo , Perfilação da Expressão Gênica , Glaucoma/patologia , Proteína Glial Fibrilar Ácida/genética , Glutamato-Cisteína Ligase/genética , Glutamato-Cisteína Ligase/metabolismo , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Potencial da Membrana Mitocondrial , Disco Óptico/patologia , Estresse Oxidativo , ATPases Transportadoras de Cálcio da Membrana Plasmática/genética , ATPases Transportadoras de Cálcio da Membrana Plasmática/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
BACKGROUND: Fibroblasts play a critical role in intestinal wound healing. Lipopolysaccharide (LPS) is a cell wall component of commensal gut bacteria. The effects of LPS on intestinal fibroblast activation were characterized. METHODS: Expression of the LPS receptor, toll-like receptor (TLR) 4, was assessed in cultured primary human intestinal fibroblasts using flow cytometry and confocal microscopy. Fibroblasts were treated with LPS and/or transforming growth factor (TGF) beta1. Nuclear factor kappaB (NFkappaB) pathway activation was assessed by inhibitory kappaBalpha (IkappaBalpha) degradation and NFkappaB promoter activity. Fibroblast contractility was measured using a fibroblast-populated collagen lattice. Smad-7, a negative regulator of TGF-beta1 signalling, and connective tissue growth factor (CTGF) expression were assessed using reverse transcriptase-polymerase chain reaction and western blot. The NFkappaB pathway was inhibited by IkappaBalpha transfection. RESULTS: TLR-4 was present on the surface of intestinal fibroblasts. LPS treatment of fibroblasts induced IkappaBalpha degradation, enhanced NFkappaB promoter activity and increased collagen contraction. Pretreatment with LPS (before TGF-beta1) significantly increased CTGF production relative to treatment with TGF-beta1 alone. LPS reduced whereas TGF-beta1 increased smad-7 expression. Transfection with an IkappaBalpha plasmid enhanced basal smad-7 expression. CONCLUSION: Intestinal fibroblasts express TLR-4 and respond to LPS by activating NFkappaB and inducing collagen contraction. LPS acts in concert with TGF-beta1 to induce CTGF. LPS reduces the expression of the TGF-beta1 inhibitor, smad-7.
Assuntos
Fibroblastos/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Receptor 4 Toll-Like/metabolismo , Fator de Crescimento Transformador beta1/farmacologia , Cicatrização/fisiologia , Idoso , Idoso de 80 Anos ou mais , Células Cultivadas , Neoplasias do Colo/metabolismo , Fator de Crescimento do Tecido Conjuntivo/biossíntese , Fibroblastos/metabolismo , Humanos , Quinase I-kappa B/metabolismo , Pessoa de Meia-Idade , NF-kappa B/metabolismo , Proteína Smad7/metabolismoRESUMO
BACKGROUND: Fibroblasts isolated from strictures in Crohn's disease (CD) exhibit reduced responsiveness to stimulation with transforming growth factor (TGF) beta1. TGF-beta1, acting through the smad pathway, is critical to fibroblast-mediated intestinal fibrosis. The membrane glycoprotein, endoglin, is a negative regulator of TGF-beta1. METHODS: Intestinal fibroblasts were cultured from seromuscular biopsies of patients undergoing intestinal resection for CD strictures or from control patients. Endoglin expression was assessed using confocal microscopy, flow cytometry and western blot. The effect of small interfering (si) RNA-mediated knockdown and plasmid-mediated overexpression of endoglin on fibroblast responsiveness to TGF-beta1 was assessed by examining smad phosphorylation, smad binding element (SBE) promoter activity, connective tissue growth factor (CTGF) expression and ability to contract collagen. RESULTS: Crohn's stricture fibroblasts expressed increased constitutive cell-surface and whole-cell endoglin relative to control cells. Endoglin co-localized with filamentous actin. Fibroblasts treated with siRNA directed against endoglin exhibited enhanced TGF-beta1-mediated smad-3 phosphorylation, and collagen contraction. Cells transfected with an endoglin plasmid did not respond to TGF-beta1 by exhibiting SBE promoter activity or producing CTGF. CONCLUSION: Fibroblasts from strictures in CD express increased constitutive endoglin. Endoglin is a negative regulator of TGF-beta1 signalling in the intestinal fibroblast, modulating smad-3 phosphorylation, SBE promoter activity, CTGF production and collagen contraction.
Assuntos
Antígenos CD/fisiologia , Fibroblastos/metabolismo , Receptores de Superfície Celular/fisiologia , Fator de Crescimento Transformador beta1/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígenos CD/metabolismo , Western Blotting , Células Cultivadas , Doença de Crohn/metabolismo , Endoglina , Humanos , Microscopia Confocal , Pessoa de Meia-Idade , Receptores de Superfície Celular/metabolismoRESUMO
BACKGROUND: The aetiology of ulcerative colitis is uncertain but may relate to environmental factors in genetically predisposed individuals. Sulphate-reducing bacteria (SRB) have been implicated through the harmful effects of hydrogen sulphide, a by-product of their respiration. Hydrogen sulphide is freely permeable to cell membranes and inhibits butyrate. This review examines the available evidence relating to SRB as a possible cause of ulcerative colitis. METHODS: A literature search was conducted using the PubMed database and search terms 'sulphate reducing bacteria', 'hydrogen sulphide', 'ulcerative colitis', 'mucous gel layer' and 'trans-sulphuration'. RESULTS: Search results were scrutinized and 113 pertinent full-text articles were selected for review. Collected data related to hydrogen sulphide metabolism, SRB respiration, mucous gel layer composition and their association with ulcerative colitis. CONCLUSION: There is evidence to implicate SRB as an environmental factor in ulcerative colitis. More sophisticated mucosal dissection and molecular techniques using bacteria-directed probes are required to determine an association definitively.
Assuntos
Colite Ulcerativa/etiologia , Infecções por Bactérias Gram-Negativas , Sulfeto de Hidrogênio/metabolismo , Bactérias Redutoras de Enxofre/metabolismo , Aminoácidos/metabolismo , Colite Ulcerativa/microbiologia , Glutationa/fisiologia , Humanos , Mucosa Intestinal/microbiologia , Tiossulfato Sulfurtransferase/metabolismoRESUMO
BACKGROUND: Transforming growth factor (TGF) beta1, acting through the smad pathway, is critical to fibroblast-mediated intestinal fibrosis. Simvastatin exhibits antifibrotic properties. This study assessed the effects of simvastatin on TGF-beta1-mediated intestinal fibroblast activation. METHODS: Human intestinal fibroblasts were activated with TGF-beta1 with or without simvastatin or the cholesterol pathway intermediates farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP). Collagen-Ialpha2 expression was assessed by reverse transcriptase-polymerase chain reaction. Connective tissue growth factor (CTGF) and smad phosphorylation were evaluated by western blot, and plasminogen activator inhibitor (PAI) 1 activity by enzyme-linked immunosorbent assay. Fibroblast filamentous (F)-actin accumulation was assessed by confocal microscopy and contraction by a fibroblast-populated collagen lattice (FPCL) model. RESULTS: TGF-beta1 treatment of fibroblasts induced smad-2/3 phosphorylation, CTGF and collagen-Ialpha2 production, F-actin bundling, FPCL contraction and PAI-1 activation. Pretreatment with simvastatin inhibited the induction of CTGF and collagen-Ialpha2, PAI-1 activation, F-actin bundling and FPCL contraction. The inhibitory effect of simvastatin on PAI-1 activation was reversed by GGPP and FPP. Simvastatin pretreatment inhibited TGF-beta1-mediated phosphorylation of smad-3. CONCLUSION: Simvastatin abrogates TGF-beta1-mediated intestinal fibroblast activation by inhibition of smad-3 phosphorylation. These findings offer a mechanism for the antifibrotic effects of simvastatin and a therapeutic entry point in the treatment of intestinal fibrosis.
Assuntos
Colo/citologia , Fibroblastos/efeitos dos fármacos , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Sinvastatina/farmacologia , Proteína Smad3/metabolismo , Fator de Crescimento Transformador beta1/efeitos dos fármacos , Actinas/metabolismo , Western Blotting , Comunicação Celular , Células Cultivadas , Fator de Crescimento do Tecido Conjuntivo/metabolismo , Ensaio de Imunoadsorção Enzimática , Fibroblastos/fisiologia , Humanos , Microscopia Confocal , Fosforilação/efeitos dos fármacos , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Crescimento Transformador beta1/fisiologiaRESUMO
PURPOSE: This study examines the effect of the L-type calcium channel blocker verapamil on mechanical strain-induced extracellular matrix genes in optic nerve head lamina cribrosa (LC) cells. METHODS: Changes in LC cell intracellular calcium [Ca(2+)]i following hypotonic cell membrane stretch were measured with the fluorescent probe fura-2/AM. Fluorescence intensity was measured, after labelling, by calcium (Ca2+) imaging confocal microscopy. Confluent human LC cell cultures were serum starved for 24â h prior to exposure to cyclical mechanical strain (1â Hz, 15%) for 24â h in the presence or absence of verapamil (10â mm). Transforming growth factor-ß 1 (TGF-ß1), collagen 6A3 (COL6A3) and chondroitin sulfate proteoglycan 2 (CSPG2) mRNA expression levels were assessed by quantitative RT-PCR. RESULTS: Hypotonic cell membrane stretch of LC cells from normal donors significantly increased [Ca2+]i (p<0.05). Exposure to cyclical mechanical strain (15% strain) produced a statistically significant increase in the three matrix genes that were examined (TGF-ß1, COL6A3 and CSPG2). This response in both cyclical and mechanical stretch was significantly reduced by pretreating LC cells with the L-type calcium channel blocker verapamil (p<0.05). CONCLUSIONS: This study provides evidence of a novel mechanotransduction pathway linking mechanical strain, cation channel function and the induction of LC cell matrix gene transcription. This highlights the potential involvement of calcium influx in the activation of matrix remodelling responses in the optic nerve head and supports the rationale that calcium channel blockers may attenuate disease progression in glaucoma.