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1.
Stress ; 22(1): 27-35, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30424700

RESUMO

The pathogenesis of post-traumatic stress disorder (PTSD) is incompletely understood. We hypothesize that disruptions in mother-child relations may be a key contributor to development of PTSD. A normal and healthy separation-individuation process requires adaptations of self- and interactive contingency in both the mother and her child, especially in early childhood development. Anxious mothers are prone to overprotection, which may hinder the individuation process in their children. We examined long-term stress hormones and other stress markers in subjects three generations removed from the Holocaust, to assess the long-term consequences of inherited behavioral and physiological responses to prior stress and trauma. Jewish subjects who recalled overprotective parental behavior had higher hairsteroid-concentrations and dampened limbic-hypothalamic-pituitary-adrenal (LHPA) axis reactivity compared to German and Russian-German subjects with overprotective parents. We suggest that altered LHPA axis activity in maternally overprotected Jewish subjects may indicate a transmitted pathomechanism of "frustrated individuation" resulting from cross-generational anti-Semitic experiences. Thus measurements of hairsteroid-concentrations and parenting practices may have clinical value for diagnosis of PTSD. We propose that this apparent inherited adaptivity of LHPA axis activity could promote higher individual stress resistance, albeit with risk of an allostatic overload.


Assuntos
Ansiedade/fisiopatologia , Ansiedade/psicologia , Sistema Hipotálamo-Hipofisário/fisiopatologia , Relações Mãe-Filho/psicologia , Adulto , Afeto , Feminino , Holocausto/psicologia , Humanos , Masculino , Mães/psicologia , Sistema Hipófise-Suprarrenal/fisiopatologia , Transtornos de Estresse Pós-Traumáticos/etiologia , Transtornos de Estresse Pós-Traumáticos/fisiopatologia , Transtornos de Estresse Pós-Traumáticos/psicologia , Estresse Psicológico/fisiopatologia , Estresse Psicológico/psicologia , Adulto Jovem
2.
Horm Metab Res ; 47(1): 72-7, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25372780

RESUMO

Revascularisation of transplanted islets is an essential prerequisite for graft survival and function. However, current islet isolation procedures deprive the islets of endothelial tubulets. This may have a detrimental effect on the revascularisation process of islets following transplantation. We hypothesise that modification of the isolation procedure that preserves islet endothelial vessels may improve the islet revascularisation process following transplantation. Here, we present a modified islet isolation method by which a substantial amount of endothelial cells still attached to the islets could be preserved. The islets with preserved endothelial cells isolated by this method were revascularised within 3 days, not observed in islets isolated by standard methods. Further, we observed that grafts of islets isolated by standard methods had more patches of dead tissue than islet grafts obtained by the modified method, indicating that attached endothelial cells may play an important role in the islet revascularisation process and potentially help to improve the transplantation outcome.


Assuntos
Sobrevivência de Enxerto , Transplante das Ilhotas Pancreáticas , Adulto , Antígenos CD/metabolismo , Biomarcadores/metabolismo , Endoglina , Células Endoteliais/metabolismo , Feminino , Humanos , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Masculino , Pessoa de Meia-Idade , Receptores de Superfície Celular/metabolismo , Doadores de Tecidos , Resultado do Tratamento
3.
Horm Metab Res ; 47(1): 24-30, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25365509

RESUMO

Transplantation of islet cells is an effective treatment for type 1 diabetes with critically labile metabolic control. However, during islet isolation, blood supply is disrupted, and the transport of nutrients/metabolites to and from the islet cells occurs entirely by diffusion. Adequate oxygen supply is essential for function/survival of islet cells and is the limiting factor for graft integrity. Recently, we developed an immunoisolated chamber system for transplantation of human islets without immunosuppression. This system depended on daily oxygen supply. To provide independence from this external source, we incorporated a novel approach based on photosynthetically-generated oxygen. The chamber system was packed sandwich-like with a slab of immobilized photosynthetically active microorganisms (Synechococcus lividus) on top of a flat light source (LEDs, red light at 660 nm, intensity of 8 µE/m(2)/s). Islet cells immobilized in an alginate slab (500-1,000 islet equivalents/cm(2)) were mounted on the photosynthetic slab separated by a gas permeable silicone rubber-Teflon membrane, and the complete module was sealed with a microporous polytetrafluorethylene (Teflon) membrane (pore size: 0.4 µm) to protect the contents from the host immune cells. Upon illumination, oxygen produced by photosynthesis diffused via the silicone Teflon membrane into the islet compartment. Oxygen production from implanted encapsulated microorganisms was stable for 1 month. After implantation of the device into diabetic rats, normoglycemia was achieved for 1 week. Upon retrieval of the device, blood glucose levels returned to the diabetic state. Our results demonstrate that an implanted photosynthetic bioreactor can supply oxygen to transplanted islets and thus maintain islet viability/functionality.


Assuntos
Transplante das Ilhotas Pancreáticas/instrumentação , Ilhotas Pancreáticas/metabolismo , Oxigênio/metabolismo , Fotossíntese , Animais , Diabetes Mellitus Experimental/metabolismo , Humanos , Masculino , Consumo de Oxigênio , Ratos Endogâmicos Lew , Reprodutibilidade dos Testes , Synechococcus/metabolismo
4.
Ann Surg Oncol ; 21(6): 1891-7, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24522991

RESUMO

BACKGROUND: Parathyroid cancer has a poor mid-term prognosis, often because of local recurrence, observed in half of all patients. Modern diagnostic workup increasingly enables a preoperative diagnosis of parathyroid cancer. There is limited evidence that more comprehensive oncologic surgery can reduce the risk of local recurrence. This study aims to identify the best specific surgical approach in parathyroid cancer. METHODS: This observational cohort study comprises 19 consecutive patients who had undergone oncologic or nononcologic resection for parathyroid cancer. Baseline parameters were compared by using univariate analysis; outcomes were assessed by χ (2) testing and Kaplan-Meier statistics. RESULTS: Fifteen of 19 patients were primarily operated on in our tertiary center between 1996 and 2013, and four were referred for follow-up because of their cancer diagnosis. Patient cohorts defined by histologic R-status were comparable for established risk factors: sex, calcium levels, low-risk/high-risk status, and presence of vascular invasion. Oncologic resections were performed in 13 of 15 patients primarily treated in the center and 0 of 4 treated elsewhere (χ (2) = 5.6; p < 0.01). R0 margins were achieved in 11 of 13 (85 %) undergoing oncologic resection and 1 of 6 (17 %) undergoing local excision (χ (2) = 8.1; p < 0.01). R0 margins and primary oncologic resection were associated with higher disease-free survival rates (χ (2) = 7.9; p = 0.005 and χ (2) = 4.7; p = 0.03, respectively). Revision surgery achieved R0 margins in only 2 of 4 (50 %) of patients. CONCLUSIONS: In parathyroid cancer, a more comprehensive surgery (primary oncologic resection) provides significantly better outcomes than local excision as a result of reduction of R1 margins and locoregional recurrence.


Assuntos
Esvaziamento Cervical , Recidiva Local de Neoplasia , Neoplasias das Paratireoides/mortalidade , Neoplasias das Paratireoides/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasia Residual , Reoperação , Estudos Retrospectivos
5.
Horm Metab Res ; 46(13): 964-73, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25014332

RESUMO

This study analyses new information on gene mutations in paragangliomas and puts them into a clinical context. A suspicion of malignancy is critical to determine the workup and surgical approach in adrenal (A-PGL) and extra-adrenal (E-PGL) paragangliomas (PGLs). Malignancy rates vary with location, family history, and gene tests results. Currently there is no algorithm incorporating the above information for clinical use. A sum of 1,821 articles were retrieved from PubMed using the search terms "paraganglioma genetics". Thirty-seven articles were selected of which 9 were analyzed. It was found that 599/2,487 (24%) patients affected with paragangliomas had a germline mutation. Of these 30.2% were mutations in SDHB, 25% VHL, 19.4% RET, 18.4% SDHD, 5.0% NF1, and 2.0% SDHC genes. A family history was positive in 18.1-64.3% of patients. Adrenal PGLs accounted for 55.1% in mutation (+) and 81.0% in mutation (-) patients (RR 1.2, p < 0.0001). Bilateral A-PGLs accounted for 56.4% in mutation (+) and 3.2% in mutation (-) patients (RR 8.7, p < 0.0001). E-PGL were found in 33.6% of mut+ and 17.3% of mut- (RR 1.7, p < 0.0001). In mutation (+) patients PGLs malignancy varied with location, adrenal (6.4%) thoraco-abdominal E-PGL (38%), H & N E-PGL (10%). Malignancy rates were 8.2% in mutation (-) and lower in mutation (+) PGLs except for SDHB 36.5% and SDHC 8.3%. Exclusion of a mutation lowered the probability of malignancy significantly in E-PGL (RR 0.03 (95% CI 0.1-0.6); p < 0.001). Mutation analysis provides valuable preoperative information to assess the risk of malignancy in A-PG and E-PGLs and should be considered in the work up of all E-PGL lesions.


Assuntos
Predisposição Genética para Doença , Paraganglioma/genética , Paraganglioma/patologia , Família , Humanos , Mutação/genética , Taxa de Mutação
6.
Mol Ecol ; 22(4): 1065-80, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23294019

RESUMO

Even though premating isolation is hypothesized to be a major driving force in speciation, its genetic basis is poorly known. In the noctuid moth Heliothis subflexa, one group of sex pheromone components, the acetates, emitted by the female, plays a crucial isolating role in preventing interspecific matings to males of the closely related Heliothis virescens, in which females do not produce acetates and males are repelled by them. We previously found intraspecific variation in acetates in H. subflexa: females in eastern North America contain significantly more acetates than females in Western Mexico. Here we describe the persistence of this intraspecific variation in laboratory-reared strains and the identification of one major quantitative trait locus (QTL), explaining 40% of the variance in acetate amounts. We homologized this intraspecific QTL to our previously identified interspecific QTL using restriction-associated DNA (RAD) tags. We found that a major intraspecific QTL overlaps with one of the two major interspecific QTL. To identify candidate genes underlying the acetate variation, we investigated a number of gene families with known or suspected acetyl- or acyltransferase activity. The most likely candidate genes did not map to our QTL, so that we currently hypothesize that a transcription factor underlies this QTL. Finding a single, large QTL that impacts variation in pheromone blends between and within species is, to our knowledge, the first such example for traits that have been demonstrated to affect premating isolation.


Assuntos
Variação Genética , Mariposas/genética , Locos de Características Quantitativas , Atrativos Sexuais/genética , Acetatos/química , Acetiltransferases/genética , Animais , Feminino , Genes de Insetos , Genética Populacional , Masculino , México , North Carolina , Fenótipo , Isolamento Reprodutivo , Atrativos Sexuais/química , Fatores de Transcrição/genética
7.
Klin Padiatr ; 225(6): 357-61, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24166093

RESUMO

Since 2007, children and adolescents with Hodgkin lymphomas are treated in the Europe-wide EuroNet-PHL trials. A real time central review process for stratification of the patients enhances quality control and efficient therapy management. This process includes reading of all cross-sectional-images. Since reference evaluation is time critical, a fast, easy to handle and safe data transfer is important. In addition, immediate and constant access to all the data has to be guaranteed in case of queries and for regulatory reasons. To meet the mentioned requirements the EuroNet Paediatric Hodgkin Data Network (funded by the European Union - Project Number: 2007108) was established between 2008 and 2011. A respective tailored data protection plan was formulated. The aim of this article is to describe the networks' mode of operation and the advantages for multi-centre trials that include centralized image review.


Assuntos
Ensaios Clínicos como Assunto/estatística & dados numéricos , Redes de Comunicação de Computadores/organização & administração , Sistemas de Gerenciamento de Base de Dados/organização & administração , Diagnóstico por Imagem , União Europeia , Doença de Hodgkin/terapia , Estudos Multicêntricos como Assunto/estatística & dados numéricos , Sistemas de Informação em Radiologia/organização & administração , Adolescente , Criança , Segurança Computacional , Coleta de Dados , Europa (Continente) , Humanos , Controle de Qualidade
8.
Internist (Berl) ; 53(4): 478, 480-5, 487, 2012 Apr.
Artigo em Alemão | MEDLINE | ID: mdl-22388922

RESUMO

The development of new drugs for the treatment of type 2 diabetes (T2DM) and metabolic disorders is currently one of the most innovative areas of drug development. However, a considerable number of newly developed drugs have either not reached the market and were stopped late in development or have been withdrawn after initial approval soon after market authorization due to serious safety concerns. How can drug safety problems be anticipated and, even more important, how can adverse events definitely caused by a drug be differentiated from incidences of naturally occurring diseases? This review article will provide an update about the state of the art treatment of type 2 diabetes and reflect on the newest available study evidence on glitazones, incretin mimetics (GLP-1 agonists and DPP-4 inhibitors), SGLT-2 inhibitors (gliflocines) and pan-PPAR agonists (glitazars). Furthermore, new and still experimental approaches for the treatment of T2DM, such as bardoxolone, salsalate and anakinra will be briefly reviewed.


Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/efeitos adversos , Humanos , Medição de Risco , Fatores de Risco
9.
Diabet Med ; 28(2): 168-74, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21219424

RESUMO

AIMS: To characterize bio-psycho-social factors, particularly mental disorders and self-harm behaviour, associated with the development of diabetic foot ulcers. METHODS: Two groups of diabetic patients with and without foot ulcers (n=47 in each group) with similar sex, age and diabetes duration were assessed for mental disorders using the Composite International Diagnostic Interview. Self-harm behaviour, quality of life, depressive symptoms and self-compassion were rated using different standard questionnaires. RESULTS: Patients from the ulcer group visited their practitioners and/or psychotherapists less frequently in the last 12 months than patients in the control group 0 vs. 13%; P=0.026). The ulcer group patients had a history of increased alcohol consumption (43 vs. 19%; P=0.025), lower levels of education (8 vs. 10 grades; P=0.014) and income (1190 vs. 1535 €/month; P=0.039). Additionally, they were less likely to be diagnosed with anxiety disorders (11 vs. 32%; P=0.022). No significant differences in glycated haemoglobin, body mass index, smoking and direct self-harm behaviour were identified. CONCLUSIONS: Patients with foot ulcers tend to exhibit lower health-conscious behaviour, particularly higher lifetime alcohol consumption, lower utilization of medical services and less general anxiety. Practitioners should be aware of these behaviours, since early detection of diabetes patients at psycho-social risk and consecutive psychological intervention may be an effective preventive strategy in avoiding the development of foot ulcers.


Assuntos
Consumo de Bebidas Alcoólicas/efeitos adversos , Diabetes Mellitus Tipo 2/complicações , Pé Diabético/etiologia , Neuropatias Diabéticas/psicologia , Comportamentos Relacionados com a Saúde , Cooperação do Paciente/psicologia , Autocuidado/psicologia , Adulto , Idoso , Consumo de Bebidas Alcoólicas/psicologia , Amputação Cirúrgica/psicologia , Diabetes Mellitus Tipo 2/fisiopatologia , Diabetes Mellitus Tipo 2/psicologia , Pé Diabético/fisiopatologia , Pé Diabético/psicologia , Neuropatias Diabéticas/complicações , Neuropatias Diabéticas/fisiopatologia , Feminino , Alemanha/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Cooperação do Paciente/estatística & dados numéricos , Fatores de Risco , Inquéritos e Questionários
10.
Mol Psychiatry ; 15(11): 1046-52, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20966918

RESUMO

Oxidative stress is an important determinant not only in the pathogenesis of Alzheimer's disease (AD), but also in insulin resistance (InsRes) and diabetic complications. Forkhead box class O (FoxO) transcription factors are involved in both insulin action and the cellular response to oxidative stress, thereby providing a potential integrative link between AD and InsRes. For example, the expression of intra- and extracellular antioxidant enzymes, such as manganese-superoxide dismutase and selenoprotein P, is regulated by FoxO proteins, as is the expression of important hepatic enzymes of gluconeogenesis. Here, we review the molecular mechanisms involved in the pathogenesis of AD and InsRes and discuss the function of FoxO proteins in these processes. Both InsRes and oxidative stress may promote the transcriptional activity of FoxO proteins, resulting in hyperglycaemia and a further increased production of reactive oxygen species (ROS). The consecutive activation of c-Jun N-terminal kinases and inhibition of Wingless (Wnt) signalling may result in the formation of ß-amyloid plaques and τ protein phosphorylation. Wnt inhibition may also result in a sustained activation of FoxO proteins with induction of apoptosis and neuronal loss, thereby completing a vicious circle from oxidative stress, InsRes and hyperglycaemia back to the formation of ROS and consecutive neurodegeneration. In view of their central function in this model, FoxO proteins may provide a potential molecular target for the treatment of both InsRes and AD.


Assuntos
Doença de Alzheimer/fisiopatologia , Fatores de Transcrição Forkhead/fisiologia , Resistência à Insulina/fisiologia , Estresse Oxidativo/fisiologia , Doença de Alzheimer/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Humanos , Modelos Biológicos , Transdução de Sinais/fisiologia
12.
Horm Metab Res ; 43(4): 268-74, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21332026

RESUMO

The phosphoinositide 3'-kinase (PI3 K)/Akt pathway controls the activity of a number of proteins important in the regulation of apoptosis and cell proliferation. FoxO (forkhead box, class O) transcription factors, substrates of the Ser/Thr kinase Akt, control the expression of several target genes that are crucial to the defense against oxidative stress, the regulation of cell cycle, and apoptosis in mammalian cells. Here, expression of ceruloplasmin (CP), the major copper-containing protein in blood released by the liver, was investigated. We observed a significant downregulation of CP mRNA levels after insulin treatment in H4IIE rat hepatoma cells. The PI3K inhibitor wortmannin counteracted this insulin effect on CP mRNA levels, indicating that the PI3K/Akt cascade is involved in the regulation of CP expression. Stimulation of FoxO1 was induced in H4IIE rat hepatoma cells expressing a conditionally active FoxO1 construct, resulting in significant upregulation of CP mRNA levels. This upregulation was prevented in the presence of insulin. In parallel, mRNAs of established FoxO target genes were analyzed: like CP mRNA, selenoprotein P and glucose 6-phosphatase mRNAs were upregulated by FoxO1, which was prevented by insulin. The same effects of insulin on CP mRNA levels were detected in primary rat hepatocytes. Furthermore, CP release into cell culture media was analyzed with primary hepatocytes and found to be attenuated by insulin. In line with its insulin-mimetic effects on cultured cells, Cu (2+) imitated the effect of insulin on CP expression and caused a downregulation of CP mRNA levels in rat hepatoma cells.


Assuntos
Ceruloplasmina/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Regulação Enzimológica da Expressão Gênica , Insulina/metabolismo , Fígado/enzimologia , Proteínas do Tecido Nervoso/metabolismo , Animais , Linhagem Celular Tumoral , Ceruloplasmina/genética , Fatores de Transcrição Forkhead/genética , Fígado/metabolismo , Proteínas do Tecido Nervoso/genética , Ratos
13.
Vet Pathol ; 48(1): 198-211, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20861499

RESUMO

A study was carried out to test the accuracy and consistency of veterinary pathologists, not specialists in hematopathology, in applying the World Health Organization (WHO) system of classification of canine lymphomas. This study represents an initiative of the ACVP Oncology Committee, and the classification has been endorsed by the World Small Animal Veterinary Association (WASVA). Tissue biopsies from cases of canine lymphoma were received from veterinary oncologists, and a study by pathologists given only signalment was carried out on 300 cases. Twenty pathologists reviewed these 300 cases with each required to choose a diagnosis from a list of 43 B and T cell lymphomas. Three of the 20 were hematopathologists who determined the consensus diagnosis for each case. The 17 who formed the test group were experienced but not specialists in hematopathology, and most were diplomates of the American or European Colleges of Veterinary Pathology. The overall accuracy of the 17 pathologists on the 300 cases was 83%. When the analysis was limited to the 6 most common diagnoses, containing 80% of all cases, accuracy rose to 87%. In a test of reproducibility enabled by reintroducing 5% of cases entered under a different identity, the overall agreement between the first and second diagnosis ranged from 40 to 87%. The statistical review included 43,000 data points for each of the 20 pathologists.


Assuntos
Doenças do Cão/classificação , Linfoma/veterinária , Animais , Cães , Linfonodos/patologia , Linfoma/classificação , Variações Dependentes do Observador , Patologia Veterinária/normas , Médicos Veterinários/normas , Organização Mundial da Saúde
14.
Horm Metab Res ; 47(6): 470-1, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25993255
16.
Horm Metab Res ; 42(7): 502-6, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20352598

RESUMO

Two strongly correlated polymorphisms located within the gene of the glucokinase regulator protein (GKRP), rs780094 and rs1260326, are associated with increased plasma triglyceride levels and provide a genetic model for the long-term activation of hepatic glucokinase. Because pharmacological glucokinase activators are evaluated for the treatment of diabetes, the aim of the study was to assess if these polymorphisms could provide evidence for an increased cardiovascular risk of long-term glucokinase activation. Therefore, these polymorphisms were tested in 3 500 patients of the Ludwigshafen Risk and Cardiovascular Health study, which was designed to assess cardiovascular risk factors. The two variants were associated with a significant increase of both plasma triglycerides (p<0.0001) and VLDL triglyceride levels (p<0.0001). Plasma free fatty acid concentrations were also significantly elevated (p<0.0078). LDL and HDL cholesterol levels were unchanged. No association was found with respect to coronary stenosis, myocardial infarction, left ventricular wall hypertrophy, and hypertension. In conclusion, long-term genetic glucokinase activation by the GKRP polymorphisms was not associated with an increased cardiovascular risk in the study population.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/genética , Ácidos Graxos não Esterificados/sangue , Glucoquinase/metabolismo , Polimorfismo Genético , Triglicerídeos/sangue , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Idoso , Idoso de 80 Anos ou mais , Doenças Cardiovasculares/sangue , Estudos de Coortes , Feminino , Alemanha , Inquéritos Epidemiológicos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fatores de Risco
17.
J Electr Bioimpedance ; 11(1): 49-56, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33584903

RESUMO

Designing proper frontend electronics is critical in the development of highly sophisticated electrode systems. Multielectrode arrays for measuring electrical signals or impedance require multichannel readout systems. Even more challenging is the differential or ratiometric configuration with simultaneous assessment of measurement and reference channels. In this work, an eight-channel frontend was developed for contacting a 2×8 electrode array (8 measurement and 8 reference electrodes) with a large common electrode to the impedance gain-phase analyzer Solartron 1260 (S-1260). Using the three independent and truly parallel monitor channels of the S-1260, impedance of trapped cells and reference material was measured at the same time, thereby considerably increasing the performance of the device. The frontend electronics buffers the generator output and applies a potentiostatic signal to the common electrode of the chip. The applied voltage is monitored using the current monitor of the S-1260 via voltage/current conversion. The frontend monitors the current through the electrodes and converts it to a voltage fed into the voltage monitors of the S-1260. For assessment of the 8 electrode pairs featured by the chip, a relay-based multiplexer was implemented. Extensive characterization and calibration of the frontend were carried out in a frequency range between 100 Hz and 1 MHz. Investigating the influence of the multiplexer and the frontend electronics, direct measurement with and without frontend was compared. Although differences were evident, they have been negligible below one per cent. The significance of measurement using the complex S-1260-frontend-electrode was tested using Kohlrausch's law. The impedance of an electrolytic dilution series was measured and compared to the theoretical values. The coincidence of measured values and theoretical prediction serves as an indicator for electrode sensitivity to cell behavior. Monitoring of cell behavior on the microelectrode surface will be shown as an example.

18.
J Cell Biol ; 125(4): 721-32, 1994 May.
Artigo em Inglês | MEDLINE | ID: mdl-8188742

RESUMO

Constitutive secretory vesicles carrying heparan sulfate proteoglycan (HSPG) were identified in isolated rat hepatocytes by pulse-chase experiments with [35S]sulfate and purified by velocity-controlled sucrose gradient centrifugation followed by equilibrium density centrifugation in Nycodenz. Using this procedure, the vesicles were separated from plasma membranes, Golgi, trans-Golgi network (TGN), ER, endosomes, lysosomes, transcytotic vesicles, and mitochondria. The diameter of these vesicles was approximately 100-200 nm as determined by electron microscopy. A typical coat structure as described for intra-Golgi transport vesicles or clathrin-coated vesicles could not be seen, and the vesicles were not associated with the coat protein beta-COP. Furthermore, the vesicles appear to represent a low density compartment (1.05-1.06 g/ml). Other constitutively secreted proteins (rat serum albumin, apolipoprotein E, and fibrinogen) could not be detected in purified HSPG-carrying vesicles, but banded in the denser fractions of the Nycodenz gradient. Moreover, during pulse-chase labeling with [35S]methionine, labeled albumin did not appear in the post-TGN vesicle fraction carrying HSPGs. These findings indicate sorting of HSPGs and albumin into different types of constitutive secretory vesicles in hepatocytes. Two proteins were found to be tightly associated with the membranes of the HSPG carrying vesicles: a member of the ADP ribosylation factor family of small guanine nucleotide-binding proteins and an unknown 14-kD peripheral membrane protein (VAPP14). Concerning the secretory pathway, we conclude from these results that ADP ribosylation factor proteins are not only involved in vesicular transport from the ER via the Golgi to the TGN, but also in vesicular transport from the TGN to the plasma membrane.


Assuntos
Proteínas de Transporte/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Complexo de Golgi/metabolismo , Heparitina Sulfato/metabolismo , Fígado/metabolismo , Proteínas de Membrana/metabolismo , Organelas/metabolismo , Proteoglicanas/metabolismo , Fatores de Ribosilação do ADP , Albuminas/metabolismo , Animais , Apolipoproteínas E/metabolismo , Células Cultivadas , Centrifugação com Gradiente de Concentração , Fibrinogênio/metabolismo , Proteoglicanas de Heparan Sulfato , Fígado/citologia , Microscopia Eletrônica , Processamento de Proteína Pós-Traducional , Ratos
19.
Horm Metab Res ; 41(10): 730-5, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19579180

RESUMO

The biguanide derivative metformin is a potent anti-diabetic drug widely used in the treatment of type 2 diabetes mellitus. Its major effect on glucose metabolism consists in the inhibition of hepatic glucose production. Since the mechanisms of metformin action are only partially understood at the molecular level, we studied the regulation of the gene promoter activity of glucose-6-phosphatase (G6Pase), the central hepatic gluconeogenic enzyme, by this drug. We have found that both metformin and insulin inhibit the basal and dexamethasone/cAMP-stimulated G6Pase promoter activity in hepatoma cells. Since one of the pharmacological targets of metformin is AMP-activated protein kinase (AMPK) and activation of AMPK is known to inhibit hepatic glucose production by the suppression of G6Pase gene transcription, we studied the effect of AMPK in this context. Under nonstimulated conditions, the inhibitory effect of both insulin and metformin was partially counteracted to a similar extent by treatment with compound C, a specific inhibitor of AMPK. In contrast, under conditions of stimulation with dexamethasone and cAMP, treatment with compound C reversed the inhibitory effect of metformin on G6Pase promoter activity to a similar extent as compared to nonstimulated conditions, whereas the effect of insulin was almost resistant to treatment with the AMPK-antagonist. These data indicate a differential AMPK-dependent regulation of G6Pase gene expression by insulin and metformin under basal and dexamethasone/cAMP-stimulated conditions.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Glucose-6-Fosfatase/metabolismo , Hipoglicemiantes/farmacologia , Insulina/farmacologia , Metformina/farmacologia , Quinases Proteína-Quinases Ativadas por AMP , Animais , Linhagem Celular Tumoral , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/enzimologia , Relação Dose-Resposta a Droga , Glucose-6-Fosfatase/genética , Fosforilação/fisiologia , Regiões Promotoras Genéticas/fisiologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases/metabolismo , RNA/química , RNA/genética , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa
20.
Physiol Meas ; 29(6): S185-92, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18544807

RESUMO

Frequency domain impedance measurements are still the common approach in assessing passive electrical properties of cells and tissues. However, due to the time requirements for sweeping over a frequency range for performing spectroscopy, they are not suited for recovering fast impedance changes of biological objects. The use of broad bandwidth excitation and monitoring the response as a function of time will greatly reduce the measurement time. The widespread usage of a square wave excitation is simple but not always the best choice. Here we consider different waveforms for excitation and discuss not only the advantages but also their limitations. Measurements in a miniaturized chamber where frequency and time domain measurements are compared show the suitability of different waveforms as excitation signals for the measurements of bio-impedance. The chirp excitation has been found to be most promising in terms of frequency range, signal-to-noise ratio and crest factor.


Assuntos
Análise Espectral/métodos , Impedância Elétrica , Microfluídica , Fatores de Tempo
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