RESUMO
Soft tissue sarcomas (STS) are rare tumors of mesenchymal origin. About 50% of patients with STS experience relapse and more than 30% will die within 10 years after diagnosis. In this study we investigated circulating free DNA (cfDNA) and tumor-specific genetic alterations therein (circulating tumor DNA, ctDNA) as diagnostic biomarkers. Plasma concentrations and fragmentation of cfDNA was analyzed with quantitative PCR. Patients with STS (n = 64) had significantly higher plasma concentrations and increased fragmentation of cfDNA when compared to patients in complete remission (n = 19) and healthy controls (n = 41) (p < 0.01 and p < 0.001). Due to overlapping values between patients with STS and controls, the sensitivity and specificity of these assays is limited. Sensitive assays to detect genomic alterations in cfDNA of synovial sarcomas (t(X;18)), myxoid liposarcomas (t(12;16) and TERT C228T promoter mutation) and well-differentiated/de-differentiated liposarcomas (MDM2 amplifications) were established. ctDNA was quantified in nine liposarcoma patients during the course of their treatment. Levels of breakpoint t(12;16) and TERT C228T ctDNA correlated with the clinical course and tumor burden in patients with myxoid liposarcomas (n = 4). ctDNA could detect minimal residual disease and tumor recurrence. In contrast, detection of MDM2 amplifications was not sensitive enough to detect tumors in patients with well-differentiated/de-differentiated liposarcomas (n = 5). Genotyping of cfDNA for tumor specific genetic alterations is a feasible and promising approach for monitoring tumor activity in patients with myxoid liposarcomas. Detection of ctDNA during follow-up examinations despite negative standard imaging studies might warrant more sensitive imaging (e.g. PET-CT) or closer follow-up intervals to timely localize and treat recurrences.
Assuntos
DNA Tumoral Circulante/genética , Lipossarcoma Mixoide/genética , Biomarcadores Tumorais/genética , Estudos de Casos e Controles , Linhagem Celular Tumoral , Ácidos Nucleicos Livres/genética , Feminino , Genótipo , Humanos , Masculino , Mutação/genética , Recidiva Local de Neoplasia/genética , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Neoplasias de Tecidos Moles/genéticaRESUMO
In linear photosynthetic electron transport, ferredoxin:NADP(H) oxidoreductase (FNR) transfers electrons from ferredoxin (Fd) to NADP+ Both NADPH and reduced Fd (Fdred) are required for reductive assimilation and light/dark activation/deactivation of enzymes. FNR is therefore a hub, connecting photosynthetic electron transport to chloroplast redox metabolism. A correlation between FNR content and tolerance to oxidative stress is well established, although the precise mechanism remains unclear. We investigated the impact of altered FNR content and localization on electron transport and superoxide radical evolution in isolated thylakoids, and probed resulting changes in redox homeostasis, expression of oxidative stress markers, and tolerance to high light in planta. Our data indicate that the ratio of Fdred to FNR is critical, with either too much or too little FNR potentially leading to increased superoxide production, and perception of oxidative stress at the level of gene transcription. In FNR overexpressing plants, which show more NADP(H) and glutathione pools, improved tolerance to high-light stress indicates that disturbance of chloroplast redox poise and increased free radical generation may help "prime" the plant and induce protective mechanisms. In fnr1 knock-outs, the NADP(H) and glutathione pools are more oxidized relative to the wild type, and the photoprotective effect is absent despite perception of oxidative stress at the level of gene transcription.
Assuntos
Adaptação Fisiológica , Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Arabidopsis/fisiologia , Ferredoxina-NADP Redutase/metabolismo , Estresse Fisiológico , Adaptação Fisiológica/efeitos da radiação , Arabidopsis/efeitos da radiação , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Glutationa/metabolismo , Luz , NADP/metabolismo , Oxirredução/efeitos da radiação , Plantas Geneticamente Modificadas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Solubilidade , Estresse Fisiológico/efeitos da radiação , Superóxidos/metabolismo , Tilacoides/metabolismoRESUMO
The production and use of engineered nanoparticles (ENPs) inevitably leads to their release into aquatic environments, with the quantities involved expected to increase significantly in the future. Concerns therefore arise over the possibility that ENPs might pose a threat to drinking water supplies. Investigations into the vulnerability of drinking water supplies to ENPs are hampered by the absence of suitable analytical methods that are capable of detecting and quantifiying ENPs in complex aqueous matrices. Analytical data concerning the presence of ENPs in drinking water supplies is therefore scarce. The eventual fate of ENPs in the natural environment and in processes that are important for drinking water production are currently being investigated through laboratory based-experiments and modelling. Although the information obtained from these studies may not, as yet, be sufficient to allow comprehensive assessment of the complete life-cycle of ENPs, it does provide a valuable starting point for predicting the significance of ENPs to drinking water supplies. This review therefore addresses the vulnerability of drinking water supplies to ENPs. The risk of ENPs entering drinking water is discussed and predicted for drinking water produced from groundwater and from surface water. Our evaluation is based on reviewing published data concerning ENP production amounts and release patterns, the occurrence and behavior of ENPs in aquatic systems relevant for drinking water supply and ENP removability in drinking water purification processes. Quantitative predictions are made based on realistic high-input case scenarios. The results of our synthesis of current knowledge suggest that the risk probability of ENPs being present in surface water resources is generally limited, but that particular local conditions may increase the probability of raw water contamination by ENPs. Drinking water extracted from porous media aquifers are not generally considered to be prone to ENP contamination. In karstic aquifers, however, there is an increased probability that if any ENPs enter the groundwater system they will reach the extraction point of a drinking water treatment plant (DWTP). The ability to remove ENPs during water treatment depends on the specific design of the treatment process. In conventional DWTPs with no flocculation step a proportion of ENPs, if present in the raw water, may reach the final drinking water. The use of ultrafiltration techniques improves drinking water safety with respect to ENP contamination.
Assuntos
Água Potável , Abastecimento de Água , Nanopartículas , Purificação da ÁguaRESUMO
BACKGROUND: Imatinib is a highly effective drug in up-front treatment of chronic myeloid leukemia (CML). In children impaired longitudinal growth has been reported as side effect exerted by this drug under prolonged therapy. We therefore prospectively evaluated alterations of bone biochemical markers in pediatric patients with CML under ongoing imatinib exposure. MATERIAL/METHODS: Bone metabolic markers (calcium, phosphate, magnesium, parathyroid hormone, vitamin D, procollagen type l N propeptide [PINP], and C-terminal cross-linking telopeptide of collagen [CTX-I], osteocalcin [OC]; pyridinoline [PYD], and desoxypyridinoline [DPD]) were determined in 17 patients with CML aged 4-17 years under imatinib treatment in three-month intervals over a 2.5 year period. RESULTS: Hyperparathyroidism developed in 8/17 patients and low 25-hydroxyvitamin-D3 levels were found in 15/17 patients. Increased OC levels were detected in 58% of all specimen showing a linear significant decline of -0.30 µg OC per l per week (p=0.04). Serum PINP was lowered in 25% and serum CTX-I was above the normal range in 57% of the specimen originating exclusively from prepupertal patients. Urine PYD and Urine DPD levels were above the normal range in 10% and 9%, respectively, of all specimen collected and a statistically significant linear decline of -0.16 nmol DPD/mg creatinine/week was calculated (p=0.01). CONCLUSIONS: Bone remodeling may be dysregulated by imatinib. Data suggest that impaired bone formation exceeds that of decreased bone resorption. Regular evaluation of the skeletal actions during long-term imatinib treatment in childhood CML is warranted.
Assuntos
Benzamidas/efeitos adversos , Benzamidas/uso terapêutico , Osso e Ossos/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Piperazinas/efeitos adversos , Piperazinas/uso terapêutico , Pirimidinas/efeitos adversos , Pirimidinas/uso terapêutico , Adolescente , Benzamidas/farmacologia , Biomarcadores Tumorais/sangue , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/patologia , Calcifediol/sangue , Criança , Pré-Escolar , Feminino , Humanos , Mesilato de Imatinib , Leucemia Mielogênica Crônica BCR-ABL Positiva/sangue , Masculino , Osteocalcina/sangue , Piperazinas/farmacologia , Pirimidinas/farmacologia , Valores de ReferênciaAssuntos
Cicloexanóis/uso terapêutico , Transtorno Depressivo Maior/tratamento farmacológico , Transtorno Depressivo Maior/urina , Mianserina/análogos & derivados , Norepinefrina/urina , Adulto , Antidepressivos de Segunda Geração/uso terapêutico , Antidepressivos Tricíclicos/uso terapêutico , Feminino , Humanos , Masculino , Mianserina/uso terapêutico , Pessoa de Meia-Idade , Mirtazapina , Cloridrato de VenlafaxinaRESUMO
BACKGROUND: Hypoxic vasodilation is a physiological response to low oxygen tension that increases blood supply to match metabolic demands. Although this response has been characterized for >100 years, the underlying hypoxic sensing and effector signaling mechanisms remain uncertain. We have shown that deoxygenated myoglobin in the heart can reduce nitrite to nitric oxide (NO·) and thereby contribute to cardiomyocyte NO· signaling during ischemia. On the basis of recent observations that myoglobin is expressed in the vasculature of hypoxia-tolerant fish, we hypothesized that endogenous nitrite may contribute to physiological hypoxic vasodilation via reactions with vascular myoglobin to form NO·. METHODS AND RESULTS: We show in the present study that myoglobin is expressed in vascular smooth muscle and contributes significantly to nitrite-dependent hypoxic vasodilation in vivo and ex vivo. The generation of NO· from nitrite reduction by deoxygenated myoglobin activates canonical soluble guanylate cyclase/cGMP signaling pathways. In vivo and ex vivo vasodilation responses, the reduction of nitrite to NO·, and the subsequent signal transduction mechanisms were all significantly impaired in mice without myoglobin. Hypoxic vasodilation studies in myoglobin and endothelial and inducible NO synthase knockout models suggest that only myoglobin contributes to systemic hypoxic vasodilatory responses in mice. CONCLUSIONS: Endogenous nitrite is a physiological effector of hypoxic vasodilation. Its reduction to NO· via the heme globin myoglobin enhances blood flow and matches O(2) supply to increased metabolic demands under hypoxic conditions.
Assuntos
Hipóxia/metabolismo , Hipóxia/fisiopatologia , Mioglobina/metabolismo , Óxido Nítrico/biossíntese , Nitritos/metabolismo , Vasodilatação/fisiologia , Adaptação Fisiológica/fisiologia , Animais , Débito Cardíaco/fisiologia , Guanilato Ciclase/metabolismo , Camundongos , Camundongos Mutantes , Músculo Liso Vascular/fisiologia , Mioglobina/genética , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/genética , Óxido Nítrico Sintase Tipo III/metabolismo , Oxigênio/sangue , Receptores Citoplasmáticos e Nucleares/metabolismo , Transdução de Sinais/fisiologia , Guanilil Ciclase SolúvelRESUMO
Patients with slow-transit constipation (STC) have delayed colonic transit for solid und liquid bowel contents but intestinal gas handling has not been studied so far. Different nutrients influence motor and sensory gut function. We hypothesized that, in patients with STC, alteration of regulatory mechanisms may result in impaired intestinal gas dynamics. On 3 separate days, validated gas challenge was performed in 10 STC patients and 10 volunteers during duodenal saline, lipids, or intravenous glucose. During saline only 60% +/- 8% of gas was cleared by STC patients after 60-min gas infusion, vs. 91% +/- 2% by controls (P < 0.001). Acute hyperglycemia or lipids did not change intestinal gas dynamics in these patients (saline infusion), but compared to healthy subjects, significant intestinal gas retention occurred. In STC, disturbances of intestinal gas dynamics include basal intestinal gas retention, and this is virtually not affected by acute hyperglycemia or duodenal lipids.
Assuntos
Doenças Funcionais do Colo/etiologia , Constipação Intestinal/complicações , Gases/metabolismo , Trânsito Gastrointestinal/fisiologia , Adulto , Doenças Funcionais do Colo/diagnóstico , Doenças Funcionais do Colo/fisiopatologia , Colonoscopia , Constipação Intestinal/diagnóstico , Constipação Intestinal/fisiopatologia , Diagnóstico Diferencial , Vias de Administração de Medicamentos , Duodeno , Feminino , Motilidade Gastrointestinal/efeitos dos fármacos , Motilidade Gastrointestinal/fisiologia , Trânsito Gastrointestinal/efeitos dos fármacos , Glucose/administração & dosagem , Humanos , Lipídeos/administração & dosagem , Pessoa de Meia-Idade , Sensação , Cloreto de Sódio/administração & dosagem , Edulcorantes/administração & dosagemRESUMO
Agrin is a heparan sulfate proteoglycan that is best known for its crucial involvement in the organization and maintenance of postsynaptic structures at the neuromuscular junction. Consistent with this role, mice deficient of agrin die at birth due to respiratory failure. Here we examined the early postnatal development of agrin-deficient mice in which perinatal death was prevented by transgenic expression of neural agrin in motor neurons. Such transgenic, agrin-deficient mice were born at Mendelian ratio but exhibited severe postnatal growth retardation. Growth plate morpholgy was markedly altered in these mice, with changes being most prominent in the hypertrophic zone. Compression of this zone was not caused by reduced viability of hypertrophic chondrocytes, as no differences in the apoptosis rates could be observed. Furthermore, deposition of the major cartilage matrix components collagen type II and aggrecan was slightly reduced in these mice. Consistent with a role for agrin in skeletal development, we show for the first time that agrin is highly expressed by chondrocytes and localizes to the growth plate in wild-type mice. Our data show that agrin is expressed in cartilage and that it plays a critical role in normal skeletal growth.
Assuntos
Agrina/genética , Condrócitos/metabolismo , Expressão Gênica , Transtornos do Crescimento/genética , Agrecanas/análise , Agrecanas/metabolismo , Agrina/metabolismo , Agrina/fisiologia , Animais , Apoptose/genética , Apoptose/fisiologia , Cartilagem/química , Cartilagem/crescimento & desenvolvimento , Cartilagem/metabolismo , Proliferação de Células , Galinhas , Condrócitos/química , Condrócitos/citologia , Colágeno Tipo II/análise , Colágeno Tipo II/metabolismo , Feminino , Transtornos do Crescimento/metabolismo , Transtornos do Crescimento/fisiopatologia , Lâmina de Crescimento/anormalidades , Lâmina de Crescimento/química , Lâmina de Crescimento/metabolismo , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Receptores Proteína Tirosina Quinases/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Under physiological conditions, the human gut adapts intestinal gas propulsion and evacuation to prevent intestinal gaseous complaints In this study we aimed to determine influences of the jejunum versus ileum on intestinal gas dynamics during a balanced meal. Paired studies were randomly performed with seven women and three men, ages 28-42. A mixed liquid meal was infused (1 kcal/min) into the duodenum. After 30 min, gas was infused (12 ml/min) into the jejunum or ileum for 150 min. Gas expulsion was measured, and perception and girth changes were assessed. Postprandial intestinal gas propulsion was uneventful and recovery complete, with -7+/- 58 and -92+/- 44 ml final intestinal gas retention for jejunal and ileal gas infusion, respectively. Neither significant differences in abdominal perception nor changes in abdominal girth were seen. During a balanced meal, intestinal gas is effectively propulsed aborally, and this does not depend on the site of the small intestinal stimulation.
Assuntos
Digestão/fisiologia , Flatulência/metabolismo , Gases/metabolismo , Íleo/fisiologia , Jejuno/fisiologia , Adulto , Feminino , Alimentos , Trânsito Gastrointestinal , Humanos , MasculinoRESUMO
OBJECTIVE: Excessive intestinal gas can be involved in postprandial abdominal symptom generation, but whether the small bowel influences intestinal gas dynamics, depending on the ingested meal, remains to be demonstrated. We compare the intestinal response to a proximal and distal small intestinal gas challenge during different duodenal nutrient components. MATERIAL AND METHODS: We randomly studied 32 healthy subjects, twice, on different days with a gas mixture infused at 12 ml/min either directly into the proximal jejunum or into the ileum; during duodenal lipids, amino acids, glucose, at 1 kcal/min each, or saline (n=8 for each group). Gas evacuation was monitored continuously and abdominal perception and girth changes were assessed. RESULTS: In response to the jejunal gas challenge, duodenal lipids delayed intestinal gas clearance more potently than amino acids (733+/-26 ml and 541+/-108 ml final gas retention; p<0.001), but when gas was directly infused into the ileum the retained volumes were much smaller (271+/-78 ml and 96+/-51 ml; p<0.001). During duodenal glucose, intestinal gas clearance following jejunal or ileal gas infusion was not significantly influenced. Abdominal perception in response to the jejunal and ileal gas challenge only increased slightly during duodenal lipids (2.0+/-0.3 score and 2.3+/-0.6 score; p<0.05 versus control). CONCLUSION: Postprandial intestinal gas clearance is hampered by duodenal lipids and amino acids but not by glucose. Specific inhibitory effects are more pronounced when gas is infused into the jejunum, which underlines the importance of the small intestine in postprandial gas retention.
Assuntos
Nutrição Enteral/métodos , Flatulência/fisiopatologia , Gases/farmacologia , Íleo/fisiopatologia , Jejuno/fisiopatologia , Adulto , Duodeno , Feminino , Flatulência/metabolismo , Trânsito Gastrointestinal/efeitos dos fármacos , Humanos , Íleo/efeitos dos fármacos , Jejuno/efeitos dos fármacos , Masculino , Percepção/fisiologia , Período Pós-PrandialRESUMO
High-caloric meals can evoke postprandial abdominal complaints involving disturbances in intestinal gas balance. We aimed to determine the influence of the caloric content of meals on intestinal gas dynamics. Eight healthy subjects (five women, three men; age range, 25-43 years) underwent paired studies with low (1 kcal/min)- and high (3 kcal/min)-caloric meal infusion 35% fat, (45% carbohydrate, 20% protein) into the duodenum in random order and proximal jejunal gas infusion. Gas evacuation, perception, and abdominal girth were assessed. The low-caloric meal caused neither gas retention (-7 +/- 58 ml) nor girth changes (0 +/- 0 mm). In contrast, the high-caloric meal led to significant gas retention (705 +/- 56 ml) and increased abdominal perimeter (7 +/- 1 mm; P < 0.001 vs. the low-caloric meal for both). Thus, a high caloric load of nutrients arriving at the duodenum modulates both intestinal gas transit and abdominal perimeter.
Assuntos
Dieta , Ingestão de Energia/fisiologia , Gases/metabolismo , Trânsito Gastrointestinal/fisiologia , Intestinos/fisiologia , Adulto , Feminino , Seguimentos , Humanos , Masculino , Valores de ReferênciaRESUMO
BACKGROUND: Especially in patients with functional intestinal disorders, impaired intestinal gas transit can be involved in abdominal symptom generation. We have previously demonstrated an acceleration of intestinal gas clearance in health during acute fasting hyperglycemia and hypothesize that in patients with functional abdominal bloating this mechanism may fail. METHODS: In 14 healthy subjects and 14 patients with functional abdominal bloating we compared effects of acute fasting hyperglycemia (approximately 12 mmol/l) and during euglycemia (control studies) on intestinal gas dynamics. Gas was infused into the jejunum (12 ml/min) for 120 min while rectal gas evacuation was continuously measured; perception and abdominal girth changes were separately evaluated. RESULTS: Marked hyperglycemia accelerated gas evacuation (-98 (53) ml 1 h intestinal gas retention) in health. In patients with functional abdominal bloating, marked hyperglycemia failed to accelerate gas transit and intestinal gas retention developed (421 (116) ml 1 h intestinal gas retention, p < 0.05 vs. health) which results in increased abdominal symptoms (perception score >3) and abdominal distension (>3 mm girth increment) as compared with control subjects (p < 0.05 for both). CONCLUSION: Intestinal gas clearance is delayed in patients with functional abdominal bloating and the increase in gas clearance during acute hyperglycemia in healthy volunteers does not occur in these patients.
Assuntos
Doenças Funcionais do Colo/fisiopatologia , Flatulência/fisiopatologia , Gases/metabolismo , Trânsito Gastrointestinal/fisiologia , Hiperglicemia/fisiopatologia , Adulto , Estudos de Casos e Controles , Doenças Funcionais do Colo/metabolismo , Eructação/fisiopatologia , Jejum , Feminino , Flatulência/metabolismo , Humanos , Intestinos/fisiologia , Masculino , Pessoa de Meia-Idade , Valores de Referência , Fatores de RiscoRESUMO
Several studies have demonstrated that cytopathogenic (cp) pestivirus strains evolve from noncytopathogenic (noncp) viruses by nonhomologous RNA recombination. In addition, two recent reports showed the rapid emergence of noncp Bovine viral diarrhea virus (BVDV) after a few cell culture passages of cp BVDV strains by homologous recombination between identical duplicated viral sequences. To allow the identification of recombination sites from noncp BVDV strains that evolve from cp viruses, we constructed the cp BVDV strains CP442 and CP552. Both harbor duplicated viral sequences of different origin flanking the cellular insertion Nedd8*; the latter is a prerequisite for their cytopathogenicity. In contrast to the previous studies, isolation of noncp strains was possible only after extensive cell culture passages of CP442 and CP552. Sequence analysis of 15 isolated noncp BVDVs confirmed that all recombinant strains lack at least most of Nedd8*. Interestingly, only one strain resulted from homologous recombination while the other 14 strains were generated by nonhomologous recombination. Accordingly, our data suggest that the extent of sequence identity between participating sequences influences both frequency and mode (homologous versus nonhomologous) of RNA recombination in pestiviruses. Further analyses of the noncp recombinant strains revealed that a duplication of 14 codons in the BVDV nonstructural protein 4B (NS4B) gene does not interfere with efficient viral replication. Moreover, an insertion of viral sequences between the NS4A and NS4B genes was well tolerated. These findings thus led to the identification of two genomic loci which appear to be suited for the insertion of heterologous sequences into the genomes of pestiviruses and related viruses.
Assuntos
Pestivirus/genética , RNA Viral/genética , Recombinação Genética , Proteínas não Estruturais Virais/genética , Animais , Bovinos , Linhagem Celular , Primers do DNA , Vírus da Diarreia Viral Bovina/genética , Duplicação Gênica , Rim , Pestivirus/crescimento & desenvolvimento , Pestivirus/patogenicidade , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ensaio de Placa ViralRESUMO
The human osteosarcoma cell line Saos-2 is widely used as a model system for human osteoblastic cells, though its phenotypic stability has not been ascertained. We therefore propagated these cells over 100 passages and compared relevant phenotypic properties. In general, higher passage cells exhibited higher proliferation rates and lower specific alkaline phosphatase activities, though mineralization was significantly more pronounced in cultures of late passage cells. Whereas expression of most genes investigated did not vary profoundly, some genes exhibited remarkable differences. Decorin, for instance, that has been discussed as a regulator of proliferation and mineralization, is strongly expressed only in early passage cells, and two receptors for pleiotrophin and midkine exhibited an almost mutually exclusive expression pattern in early and late passage cells, respectively. Our observations indicate that special care is required when results obtained with Saos-2 cells with different culture history are to be compared.
Assuntos
Técnicas de Cultura de Células/métodos , Instabilidade Genômica/genética , Osteoblastos/citologia , Osteoblastos/fisiologia , Osteossarcoma/genética , Osteossarcoma/patologia , Fenótipo , Evolução Biológica , Diferenciação Celular , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Matriz Extracelular/fisiologia , Matriz Extracelular/ultraestrutura , Variação Genética/genética , Substâncias de Crescimento/biossíntese , Substâncias de Crescimento/genética , HumanosRESUMO
BACKGROUND: Acute hyperglycemia usually inhibits gastrointestinal motility and hyperinsulinemia may contribute to specific inhibitory effects. However, the influences on postprandial intestinal gas dynamics have not been investigated. AIMS: To compare effects of euglycemic hyperinsulinemia and acute fasting hyperglycemia on intestinal gas dynamics in nondiabetics. METHODS: On 3 separate days, 10 healthy volunteers were evaluated in randomized order with duodenal glucose, intravenous glucose or saline infusion. Rectal gas evacuation was continuously measured; perception and abdominal girth changes were separately evaluated. After 60 min equilibration, proximal jejunal gas infusion (12 ml/min) was started for 150 min. RESULTS: Acute hyperglycemia failed to cause significant intestinal gas retention (72 +/- 64 ml and 53 +/- 29 ml final gas retention vs. saline); in contrast, gas clearance was expedited, with a maximal effect between 30 and 105 min (p < 0.001 vs. control). Euglycemic hyperinsulinemia did not significantly influence intestinal gas clearance and no relevant changes of abdominal girth or abdominal and rectal perception were seen, as compared to control (p > 0.05 for all parameters). CONCLUSION: Accelerated intestinal gas clearance under hyperglycemia is one physiologic factor to avoid postprandial intestinal gas accumulation. Specific underlying mechanisms, which need further investigation, may be disturbed in symptomatic patients.
Assuntos
Gases/metabolismo , Trânsito Gastrointestinal/fisiologia , Hiperglicemia/metabolismo , Mucosa Intestinal/metabolismo , Abdome/fisiopatologia , Doença Aguda , Adulto , Glicemia/metabolismo , Vias de Administração de Medicamentos , Feminino , Trânsito Gastrointestinal/efeitos dos fármacos , Glucose/administração & dosagem , Glucose/farmacocinética , Humanos , Hiperglicemia/induzido quimicamente , Hiperglicemia/fisiopatologia , Intestinos/efeitos dos fármacos , Intestinos/fisiopatologia , Masculino , Valores de Referência , Reflexo/fisiologia , Edulcorantes/administração & dosagem , Edulcorantes/farmacocinéticaRESUMO
BACKGROUND: PITX2 is a bicoid-related homeodomain transcription factor that plays an important role in asymmetric cardiogenesis. Loss of function experiments in mice cause severe heart malformations, including transposition of the great arteries (TGA). TGA accounts for 5-7% of all congenital heart diseases affecting 0.2 per 1000 live births, thereby representing the most frequent cyanotic heart defect diagnosed in the neonatal period. METHODS: To address whether altered PITX2 function could also contribute to the formation of dTGA in humans, we screened 96 patients with dTGA by means of dHPLC and direct sequencing for mutations within the PITX2 gene. RESULTS: Several SNPs could be detected, but no stop or frame shift mutation. In particular, we found seven intronic and UTR variants, two silent mutations and two polymorphisms within the coding region. CONCLUSION: As most sequence variants were also found in controls we conclude that mutations in PITX2 are not a common cause of dTGA.
Assuntos
Análise Mutacional de DNA/métodos , Proteínas de Homeodomínio/genética , Fatores de Transcrição/genética , Transposição dos Grandes Vasos/etiologia , Transposição dos Grandes Vasos/genética , Processamento Alternativo/genética , Testes Genéticos/métodos , Variação Genética/genética , Humanos , Íntrons/genética , Isoformas de Proteínas/genética , Regiões não Traduzidas/genética , Proteína Homeobox PITX2RESUMO
Bone adaption upon mechanical stimulation is accompanied by changes in gene expression. In this context we investigated the influence of mechanical loading on heparin binding growth associated molecule (HB-GAM) expression, an extracellular matrix molecule which in cell culture has been shown to stimulate the differentiation of osteoblasts. We obtained information on the participating signal transduction pathways using a mitogenic loading regimen. Specific inhibitors of various signal transduction pathways were added to loaded cells and to unloaded controls. By semi-quantitative PCR studies we demonstrated a rapid decrease of HB-GAM expression in primary osteoblasts and SaOs-2 cells by 20-30% upon mechanical loading within 30min. We showed that the RGD-integrin interaction is involved in the regulation of HB-GAM expression. Furthermore, integrity of the cytoskeleton, stretch-activated, and voltage-sensitive Ca(2+) channels as well as gap junctional communication are necessary for the downregulation of HB-GAM expression by mechanical loading.