RESUMO
AIM: Atrophic gastritis (AG), first step in the cascade leading to gastric adenocarcinoma, is related to Helicobacter pylori (H. pylori) infection. Currently, the gold standard for the diagnosis of AG is esophagogastroduodenoscopy (EGD) with histological examination of the biopsy specimens. However, since the latter are taken in random order and the distribution of AG is often patchy, histology is only representative of mucosal status. Considering this limitation, a test named GastroPanel®, that measures the blood concentrations of pepsinogen I and II, gastrin-17 and H. pylori antibodies, has been developed as a potential non-invasive biopsy. Aim of this study has been to assess the accuracy of GastroPanel® in patients with AG. METHODS: Forty-seven dyspeptic patients (24 males, mean age 52.2±9.3 years), in follow-up for antral or diffuse AG, were enrolled. All underwent at least two EGDs with random biopsies and blood collection for GastroPanel® parameters examination. RESULTS: Of the 47 patients, 16 (34.1%) had histological diagnosis of antral and 31 (65.9%) multifocal AG; 17 (36.2%) patients had mild and 30 (63.8%) had moderate-severe AG. H. pylori was detected in 39 (82.9%) and intestinal metaplasia was found in all patients. GastroPanel® showed 82.9% sensitivity for the diagnosis of AG and 53.8% for the diagnosis of H. pylori infection. The prediction of advanced atrophy was not sufficiently accurate, neither in patients with antral nor in those with multifocal AG. CONCLUSION: GastroPanel® can be useful for detecting patients with AG. However, it does not reflect the severity of atrophy.
Assuntos
Biomarcadores/sangue , Mucosa Gástrica/patologia , Gastrite Atrófica/diagnóstico , Infecções por Helicobacter/diagnóstico , Helicobacter pylori/imunologia , Adulto , Anticorpos Antibacterianos/sangue , Biópsia , Dispepsia , Endoscopia do Sistema Digestório , Feminino , Seguimentos , Gastrinas/sangue , Gastrite Atrófica/sangue , Gastrite Atrófica/microbiologia , Gastrite Atrófica/patologia , Infecções por Helicobacter/sangue , Infecções por Helicobacter/complicações , Infecções por Helicobacter/patologia , Helicobacter pylori/isolamento & purificação , Humanos , Masculino , Pessoa de Meia-Idade , Pepsinogênio A/sangue , Pepsinogênio C/sangue , Valor Preditivo dos Testes , Sensibilidade e Especificidade , Índice de Gravidade de DoençaRESUMO
Background: In the last decade many clinical research centers in Italy have increasingly implemented and improved their quality standards and effectiveness of processes through the adoption of a quality management system also according to the certification ISO 9001:2015. Objective: The aim of this project is to evaluate expected benefits and barriers of ISO 9001 certification for a Clinical Trial Center. Material and methods: On April 2021, the Italian Group of Data Manager and Clinical Research Coordinator spread an anonymous online survey to healthcare professionals operating in clinical research and quality management systems at research sites. Results: Reported benefits of ISO oriented Quality Management System adoption include continual improvement and better-quality processes (73.3%), assuring corrective actions (63.6%), planning internal audits (60.2%) and risk management approach (60.7%). The most important barriers to QMS implementation are increased logistical and/or organizational activities (40.9%) and insufficient training on quality programs (29.5%). Conclusions: Implementing a quality management system represents a challenge for the Clinical Trial Center and helps to improve quality standards and risk management approach. The use of electronic tools is poor and could be increased in the future. Lastly, improvement of continuous QMS trainings should be necessary for updating professionals and optimizing activities within the Clinical Trial Center.
RESUMO
The association between choline uptake and androgen receptor (AR) expression is suggested by the upregulation of choline kinase-alpha in prostate cancer. Recently, detection of AR aberration in cell-free DNA as well as early 18F-fluorocholine positron emission tomography/computed tomography (FCH-PET/CT) were associated with outcome in metastatic castration-resistant prostate cancer (mCRPC) patients treated with abiraterone and enzalutamide. We aimed to make a direct comparison between circulating AR copy number (CN) and choline uptake at FCH-PET/CT. We analysed 80 mCRPC patients progressing after docetaxel treated with abiraterone (n = 47) or enzalutamide (n = 33). We analysed AR CN from plasma samples using digital PCR and Taqman CN assays and total lesion activity (TLA) and metabolic tumor volume (MTV) on FCH-PET/CT at baseline. A meaningful correlation was showed among AR gain and TLA/MTV compared to AR non-gained cases (P = 0.001 and P = 0.004, respectively), independently from type of treatment. Multivariate analysis revealed that AR CN and only TLA were associated with both shorter PFS (P < 0.0009 and P = 0.026, respectively) and OS (P < 0.031 and P = 0.039, respectively). AR gain appeared significantly correlated with choline uptake represented mainly by TLA. Further prospective studies are warranted to better address this pathway of AR-signalling and to identify multiplex biomarker strategies including plasma AR and FCH-PET/CT in mCRPC patients.
Assuntos
Adenocarcinoma/tratamento farmacológico , Cloro/metabolismo , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Receptores Androgênicos/sangue , Receptores Androgênicos/genética , Adenocarcinoma/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Androstenos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Benzamidas , Biomarcadores Tumorais/metabolismo , Colina/análogos & derivados , Colina/metabolismo , Docetaxel/uso terapêutico , Dosagem de Genes , Humanos , Masculino , Pessoa de Meia-Idade , Nitrilas , Feniltioidantoína/análogos & derivados , Feniltioidantoína/uso terapêutico , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Neoplasias de Próstata Resistentes à Castração/sangue , Transdução de SinaisRESUMO
The occurrence of ichthyosis in two Italian Chianina calves is described for the first time. Both animals, affected by ichthyosis fetalis and ichthyosis congenita, respectively, showed diffuse cutaneous thickening which had been present since birth. The first patient was a three-month-old female calf; inelastic leather cuirass-like skin associated with generalized hypotrichosis and local alopecia, delay of the physiologic change of coat colour, stiff movement and growth retardation were the most prominent clinical characteristics. The patient was kept under observation for almost one year. The second case occurred in a 18-day-old female calf which was referred to our clinic after it had already died; the presence of irregular hyperkeratotic plates separated by deep fissures over the entire cutaneous surface and the slight eversion of the mucocutaneous junction (eclabium and ectropion) were the most characteristic alterations. In both cases, the major histopathological feature was a diffuse lamellar orthokeratotic hyperkeratosis. An underlying genetic defect was strongly suspected on the basis of a common ancestor for the two sires of the affected calves and of the current scientific knowledge.
Assuntos
Doenças dos Bovinos/diagnóstico , Ictiose/veterinária , Pele/patologia , Animais , Animais Recém-Nascidos , Bovinos , Doenças dos Bovinos/genética , Doenças dos Bovinos/patologia , Diagnóstico Diferencial , Evolução Fatal , Feminino , Ictiose/diagnóstico , Ictiose/genéticaRESUMO
This article reviews the experimental evidence suggesting that cytosolic Ca(2+) overload plays a major role in the development of myocardial injury during ischemia-reperfusion and that Ca(2+) release from the sarcoplasmic reticulum (SR) is of crucial importance in the early phase of ischemia. It is suggested that interventions able to deplete the SR Ca(2+) pool and/or to reduce the rate of SR Ca(2+) release should be cardioprotective. This thesis is supported by the review of experimental studies in which modulators of the SR Ca(2+)-ATPase or SR Ca(2+) release channel (ryanodine receptor) have been used. In addition, the role of the SR in ischemic preconditioning and in some instances of toxic myocardial injury (particularly, anthraquinone-induced injury) is discussed.
Assuntos
Cálcio/metabolismo , Traumatismo por Reperfusão Miocárdica/etiologia , Retículo Sarcoplasmático/fisiologia , ATPases Transportadoras de Cálcio/metabolismo , Humanos , Precondicionamento Isquêmico , Isquemia Miocárdica/metabolismo , Isquemia Miocárdica/fisiopatologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miocárdio/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/farmacologiaRESUMO
OBJECTIVE: Stimulation of A3 adenosine receptors has been shown to protect cardiac myocytes from ischemic injury, but the mechanism of this action is unknown. We evaluated the effect of adenosine agonists and antagonists on the sarcoplasmic reticulum (SR) Ca(2+) channels. METHODS: Isolated rat hearts were perfused with control buffer or different adenosine agonists and antagonists. Hearts were then homogenized and used to determine SR Ca(2+)-induced Ca(2+) release, assayed by quick filtration technique after loading with 45Ca(2+), and the binding of [3H]ryanodine, a specific ligand of the SR Ca(2+) release channel. In parallel experiments, hearts were challenged with 30 min of global ischemia and 120 min of reperfusion, and the extent of tissue necrosis was evaluated by triphenyltetrazolium chloride staining. RESULTS: Perfusion with the A1>A3 agonist R-PIA and the A3>A1 agonist IB-MECA was associated with reduced [3H]ryanodine binding, due to reduced B(max) (by about 20%), whereas K(d) and Ca(2+)-dependence of the binding reaction were unaffected. These actions were abolished by the A3 antagonist MRS 1191, while they were not affected by A1 and A2 antagonists. The rate constant of SR Ca(2+) release decreased by 25-30% in hearts perfused with R-PIA or IB-MECA. Tissue necrosis was significantly reduced in the presence of R-PIA or IB-MECA. Protection was removed by MRS 1191, and it was not affected by A1 and A2 antagonists. Hearts were also protected by administration of dantrolene, a ryanodine receptor antagonist. In the presence of dantrolene, no further protection was provided by IB-MECA. CONCLUSION: A3 adenosine receptor stimulation modulates the SR Ca(2+) channel. This action might account for the protective effect of adenosine.
Assuntos
Adenosina/análogos & derivados , Cálcio/metabolismo , Miocárdio/metabolismo , Receptores Purinérgicos P1/metabolismo , Retículo Sarcoplasmático/metabolismo , Adenosina/agonistas , Adenosina/antagonistas & inibidores , Adenosina/metabolismo , Adenosina/uso terapêutico , Animais , Dantroleno/metabolismo , Hemodinâmica/efeitos dos fármacos , Masculino , Relaxantes Musculares Centrais/metabolismo , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Técnicas de Cultura de Órgãos , Ratos , Receptor A3 de Adenosina , Rianodina/metabolismo , Vasodilatadores/uso terapêuticoRESUMO
OBJECTIVE: The aim was to detect cardiac A2 adenosine receptors through radioligand binding, and to assess the effect of ischaemia on these receptors. METHODS: Isolated working rat hearts were subjected either to aerobic perfusion or to global ischaemia. A membrane fraction was prepared from ventricular tissue, and 3H-5'-N-ethylcarboxamide adenosine (NECA) binding was determined in the presence of N6-cyclopentyl adenosine (CPA). A2 binding was calculated as the fraction of NECA binding displaced by 100 microM CPA but not displaced by 50 nM CPA. RESULTS: Analysis of A2 NECA binding according to single binding site model yielded Kd = 22.0 nM, Bmax = 34.0 fmol.mg-1 in control hearts; Kd = 49.7 nM, Bmax = 44.3 fmol.mg-1 in hearts subjected to 30 min ischaemia (p < 0.05 for difference in Kd). In the control group a two site model provided a significantly (p < 0.05) better fit (Kd = 5.6 and 183.7 nM, Bmax = 9.5 and 64.4 fmol.mg-1 for the high and low affinity sites respectively). The high affinity component of A2 NECA binding disappeared in the presence of the GTP analogue guanyl-5'-yl imidodiphosphate, suggesting the existence of multiple coupling states of the receptor. In the ischaemic group no significant improvement in data fitting was obtained with the two site model. CONCLUSIONS: The results provide evidence of the existence of cardiac A2 adenosine receptors. Ischaemia modifies receptor properties and appears to affect chiefly the high affinity component of A2 binding, possibly by preventing receptor interaction with membrane G proteins.
Assuntos
Miocárdio/metabolismo , Receptores Purinérgicos/metabolismo , Adenosina/análogos & derivados , Adenosina/metabolismo , Adenosina-5'-(N-etilcarboxamida) , Animais , Circulação Coronária , Isquemia/metabolismo , Ratos , Ratos EndogâmicosRESUMO
OBJECTIVE: We investigated the effect of ischemia on cardiac dihydropyridine receptors, which correspond to L-type sarcolemmal calcium channels. METHODS: Isolated working rat hearts were perfused aerobically for 10 min, and then subjected to 10-60 min of global ischemia. Control hearts were perfused aerobically for 30 min. [3H]PN 200-110 binding was measured in the unfractionated homogenate, in a crude membrane preparation and in a microsomal fraction. RESULTS: In the homogenate obtained from control hearts, the Kd and Bmax averaged 0.23 +/- 0.05 nM and 84 +/- 4 fmol/mg protein, respectively, and ischemia did not produce any significant change in these variables. Similar results were obtained in the crude membrane preparation (Kd = 0.29 +/- 0.08 nM, Bmax = 113 +/- 7 fmol/mg, yield of binding sites = 98 +/- 6%, no significant change in these variables during ischemia). On the contrary, in the microsomal fraction, the Bmax for [3H]PN 200-110 decreased after ischemia (115 +/- 15 fmol/mg after 20 min of ischemia vs. 190 +/- 34 fmol/mg in the control condition, P < 0.05), without any change in the Kd. In this fraction, the yield for PN 200-110 binding sites was 4.7 +/- 0.6% in the control condition and 2.8 +/- 0.5% after ischemia (P < 0.05). The yield of other sarcolemmal markers such as [3H]quinuclidinyl benzylate and [3H]ouabain binding sites was not reduced in the microsomal fraction obtained ischemic hearts. CONCLUSIONS: The total number of cardiac dihydropyridine binding sites was not downregulated during ischemia, although their distribution after tissue fractionation was slightly modified, possibly reflecting receptor redistribution between different subcellular pools.
Assuntos
Canais de Cálcio/metabolismo , Regulação para Baixo , Isquemia Miocárdica/metabolismo , Miocárdio/metabolismo , Receptores Colinérgicos/metabolismo , Animais , Canais de Cálcio Tipo L , Membrana Celular/metabolismo , Isradipino/metabolismo , Isradipino/farmacologia , Microssomos/metabolismo , Perfusão , Ligação Proteica , Ratos , Ratos Sprague-DawleyRESUMO
A purinergic receptor was identified in human myometrium membranes using 5'-N-[3H]ethylcarboxamide-adenosine [( 3H] NECA) as radioligand. Scatchard analysis of the binding data gave a Kd of 123 nM with 2.3 pmol ligand bound/mg protein. Displacement studies indicated that the binding site had the characteristics of the A2 adenosine receptors and some of those of the P2 purinoceptors since it was inhibited by two slowly degradable ATP derivatives with IC50 values comparable to that of NECA. The receptor was solubilized with sodium cholate and its binding properties were the same as those of the membrane-bound form. No -SH group appeared to be essential for the binding activity. By density gradient centrifugation the purinergic receptor-detergent complex was estimated to have an apparent molecular mass of 95 kDa.
Assuntos
Miométrio/metabolismo , Receptores de Superfície Celular/metabolismo , Adenosina/análogos & derivados , Adenosina/metabolismo , Adenosina-5'-(N-etilcarboxamida) , Membrana Celular/metabolismo , Ácido Cólico , Ácidos Cólicos , Estabilidade de Medicamentos , Feminino , Humanos , Cinética , Peso Molecular , Receptores Purinérgicos , SolubilidadeRESUMO
1. The use of anthraquinone antineoplastic agents is limited by their cardiac toxicity, which is largely due to activation of the sarcoplasmic reticulum (SR) Ca(2+) release channel (ryanodine receptor). MEN 10755 is a new disaccharide analogue of doxorubicin. We have evaluated its effects on SR function and its toxicity in isolated working rat hearts. 2. In rat SR vesicles, doxorubicin stimulated [(3)H]-ryanodine binding by increasing its Ca(2+)-sensitivity. At 1 microM Ca(2+), ryanodine binding increased by 15.3+/-2.5 fold, with EC(50)=20.6 microM. Epirubicin produced a similar effect, i.e. 9.7+/-0.6 fold stimulation with EC(50)=11.1 microM. MEN 10755 increased ryanodine binding by 1.9+/-0.3 fold (P:<0.01 vs doxorubicin and epirubicin), with EC(50)=38.9 microM. 3. Ca(2+)-induced Ca(2+) release experiments were performed by quick filtration technique, after SR loading with (45)Ca(2+). At 2 microM Ca(2+), doxorubicin (50 microM) increased the rate constant of Ca(2+) release to 82+/-5 s(-1) vs a control value of 22+/-2 s(-1) (P:<0.01), whereas 50 microM MEN 10755 did not produce any significant effect (24+/-3 s(-1)). 4. Ca(2+)-ATPase activity and (45)Ca(2+)-uptake were not significantly affected by doxorubicin, its 13-dihydro-derivative, epirubicin, MEN 10755 and the 13-dihydro-derivative of MEN 10755, at concentrations < or =100 microM. 5. In isolated heart experiments, administration of 30 microM doxorubicin or epirubicin caused serious contractile impairment, whereas 30 microM MEN 10755 produced only minor effects. 6. In conclusion, in acute experiments MEN 10755 was much less cardiotoxic than equimolar doxorubicin or epirubicin. This result might be accounted for by reduced activation of SR Ca(2+) release.
Assuntos
Cálcio/metabolismo , Dissacarídeos/farmacologia , Doxorrubicina/análogos & derivados , Doxorrubicina/farmacologia , Coração/efeitos dos fármacos , Retículo Sarcoplasmático/efeitos dos fármacos , Animais , Antibióticos Antineoplásicos/farmacologia , Antineoplásicos/farmacologia , ATPases Transportadoras de Cálcio/metabolismo , Epirubicina/farmacologia , Coração/fisiologia , Técnicas In Vitro , Masculino , Contração Miocárdica/efeitos dos fármacos , Ratos , Ratos Wistar , Rianodina/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/enzimologia , Retículo Sarcoplasmático/metabolismo , TrítioRESUMO
1. In a sarcoplasmic reticulum fraction obtained from rat hearts, the analysis of equilibrium [3H]-ryanodine binding showed high and low affinity sites (KD = 1.3 nM and 2.8 microM, Bmax = 2.2 pmol mg-1 and 27.8 pmol mg-1). The dissociation rate constant increased at 1 microM vs 4 nM [3H]-ryanodine concentration, and micromolar ryanodine slowed the dissociation of nanomolar ryanodine. 2. The binding of 4 nM [3H]-ryanodine was not affected by gallopamil, while the binding of 100 nM to 18 microM [3H]-ryanodine was partly displaced. Data analysis suggested that gallopamil inhibited low affinity [3H]-ryanodine binding, with IC50 in the micromolar range. 3. Gallopamil decreased the dissociation rate constant of 1 microM [3H]-ryanodine. While gallopamil alone did not affect the dissociation of 4 nM [3H]-ryanodine, gallopamil and micromolar ryanodine slowed it to a greater extent than micromolar ryanodine alone. 4. Our results are consistent with the hypothesis that the ryanodine receptor is a negatively cooperative oligomer, which undergoes a sequential alteration after ryanodine binding. Gallopamil has complex actions: it inhibits ryanodine binding to its low affinity site(s), and probably modulates the cooperativity of ryanodine binding and/or the transition to a receptor state characterized by slow ryanodine dissociation. These molecular actions could account for the previously reported effect of gallopamil on the sarcoplasmic reticulum calcium release channel.
Assuntos
Galopamil/farmacologia , Rianodina/farmacologia , Retículo Sarcoplasmático/efeitos dos fármacos , Animais , Associação , Sítios de Ligação , Canais de Cálcio/farmacologia , Transtornos Dissociativos , Relação Dose-Resposta a Droga , Galopamil/farmacocinética , Cinética , Ratos , Ratos Sprague-DawleyRESUMO
The effects of total sleep deprivation (SD) on the expression of the immediate-early gene NGFI-A were studied in the rat brain by in situ hybridization. Rats were manually sleep-deprived for 3, 6, 12 and 24 h starting at light onset (08:00 h) and for 12 h starting at dark onset (20:00 h). SD performed during the day induced a marked increase in NGFI-A mRNA levels with respect to sleep controls in many cerebrocortical areas and caudate-putamen, which was most evident after 6 h SD. A decrease was seen in hippocampus and thalamus, particularly after 12 h SD. Rats sleep-deprived for 12 h during the night showed an increase in NGFI-A expression in some cortical areas while rats sleep-deprived for 24 h showed few changes with respect to controls. The pattern of NGFI-A expression after forced wakefulness showed some differences from that observed after spontaneous wakefulness [M. Pompeiano, C. Cirelli and G. Tononi, Immediate early genes in spontaneous wakefulness and sleep: expression of c-fos and NGFI-A mRNA and protein, J. Sleep Res., 3 (1994) 80-96]. These observations are discussed with respect to the functional consequences of wakefulness in specific brain areas.
Assuntos
Encéfalo/metabolismo , Proteínas de Ligação a DNA/metabolismo , Genes Precoces/genética , Proteínas Imediatamente Precoces , Privação do Sono/fisiologia , Fatores de Transcrição/metabolismo , Animais , Proteína 1 de Resposta de Crescimento Precoce , Expressão Gênica , Genes fos/genética , Hibridização In Situ , Masculino , RNA Mensageiro/metabolismo , Ratos , Ratos Endogâmicos WKYRESUMO
OBJECTIVE: To investigate ictal motor inhibition occurring during seizures in a patient with a tumor located in the left fronto-mesial pre-central cortex. METHODS: Awake and sleep video-polygraphic monitoring, recording scalp EEG and EMG activities from several cranial, trunk and limbs muscles, was performed in a patient with drug-resistant recurrent focal motor seizures before surgical treatment. Speech/motor tasks were repeatedly administered to the patient during the recording sessions in order to evaluate the occurrence of early ictal motor inhibition. RESULTS: Thirty-four seizures were recorded during wakefulness showing a stereotyped pattern of inhibition of speech and voluntary movements followed by sequential activation of upper limb-trunk-lower limb muscles contralateral to the tumor. Polygraphic recordings showed that: (1) initial speech and motor arrest were associated with the EMG evidence of progressive muscle tone suppression in cranial and right distal upper limb muscles; (2) tonic contraction of right deltoid, biceps brachii, intercostalis and paraspinalis muscles appeared after motor inhibition; (3) tonic-clonic activity in the right tibialis anterior muscle occurred at the end of seizures. Eleven subclinical seizures were recorded during sleep showing mild focal tonic EMG activity in right side trunk muscles. CONCLUSIONS: Our findings evidenced early and somatotopically organized inhibition of voluntary movement at the beginning of epileptic seizures with fronto-mesial onset. The demonstration that speech and motor arrest were associated with progressive EMG suppression in cranial and limb muscles supports the hypothesis of motor inhibitory seizures originating in the mesial aspect of pre-motor frontal cortex.
Assuntos
Neoplasias Encefálicas/complicações , Neoplasias Encefálicas/fisiopatologia , Eletroencefalografia , Epilepsia/complicações , Epilepsia/fisiopatologia , Transtornos dos Movimentos/etiologia , Distúrbios da Fala/etiologia , Epilepsia/etiologia , Epilepsia do Lobo Frontal/complicações , Epilepsia do Lobo Frontal/fisiopatologia , Feminino , Humanos , Pessoa de Meia-Idade , Transtornos dos Movimentos/fisiopatologia , Distúrbios da Fala/fisiopatologia , Fatores de Tempo , VigíliaRESUMO
The effect of the association of carnitine and coenzyme Q10 on doxorubicin cardiotoxicity has been investigated. The two drugs administered to rats for two weeks have lower protective activity when they are administered separately rather than given in association (carnitine 200 mg/kg/day, coenzyme Q10 10 mg/kg/day) for the acute toxic effect of doxorubicin on perfused functioning isolated hearts. The sarcoplasmic reticulum damage measured by calcium-uptake is lower in rat hearts treated with the combined drugs. Deferoxamine and phosphocreatine, two compounds which protect from peroxidative damage due to iron and copper ions, show very strong protection from acute doxorubicin toxicity in isolated perfused hearts. Carnitine and coenzyme Q10 do not protect sarcoplasmic reticulum from iron ions damage, suggesting that their mechanism of protection is not directly related to peroxidation due to metal ion-dependent cardiotoxicity of doxorubicin.
Assuntos
Antibióticos Antineoplásicos/toxicidade , Cálcio/metabolismo , Carnitina/farmacologia , Miocárdio/metabolismo , Retículo Sarcoplasmático/metabolismo , Ubiquinona/análogos & derivados , Animais , Coenzimas , Circulação Coronária/efeitos dos fármacos , Doxorrubicina/toxicidade , Combinação de Medicamentos , Compostos Ferrosos/farmacologia , Masculino , Miocárdio/ultraestrutura , Oxalatos/farmacologia , Perfusão , Ratos , Ratos Sprague-Dawley , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/ultraestrutura , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/metabolismo , Ubiquinona/farmacologiaRESUMO
High-pressure liquid chromatography (reverse-phase mode) was used to assay adenosine kinase in cell and tissue extracts. The method is optimized for a rapid and selective analysis using 6-methylthiopurine riboside as substrate, isocratic elution and detection at 300 nm. A complete separation of substrate and product is achieved in about 3 min with no interference by other UV-absorbing compounds; the limit of detection is 20 pmoles.
Assuntos
Adenosina Quinase/análise , Fosfotransferases/análise , Animais , Cromatografia Líquida de Alta Pressão/métodos , Eritrócitos/enzimologia , Humanos , Cinética , Fígado/enzimologia , Linfócitos/enzimologia , Metiltioinosina/metabolismo , Microquímica/métodos , Ratos , Espectrofotometria UltravioletaRESUMO
The release of purine compounds from the perfused rat heart under basal conditions was determined by high pressure liquid chromatography. Uric acid resulted the major degradative released into the perfusate. Lower levels of hypoxanthine, xanthine and inosine were found. The uric acid concentration showing that the rat heart is able to catabolize the purine compounds up to uric acid. No leakage of catabolic enzymes was observed and thereby the breakdown of the released nucleosides and bases proved to be intracellular. This heart ability was confirmed by the analysis of the degradation products of AMP added to the perfusion medium in the recirculating system. AMP was sequentially broken down to adenosine, then to inosine, hypoxanthine and xanthine and finally to uric acid that as end product accumulated in the perfusate.
Assuntos
Miocárdio/metabolismo , Ácido Úrico/metabolismo , Monofosfato de Adenosina/metabolismo , Animais , Cromatografia Líquida de Alta Pressão , Hipoxantinas/metabolismo , Inosina/metabolismo , Masculino , Perfusão , Ratos , Ratos Endogâmicos , Xantinas/metabolismoRESUMO
The hydrolysis rate of 9-chloro-11 beta, 17a-dihydroxy-16 beta-methyl-21-(1'4'N-acetyltransaminomethyl- cyclohexancarbonyloxy) pregna-1,4-diene-3,20-dione (cyclomethasone) and of beclomethasone 17,21-dipropionate was studied on human lung slices. Cyclomethasone is hydrolysed more slowly than beclomethasone 17,21-dipropionate. This difference may be ascribed to a different affinity and/or activity of the tissue esterases towards the two substrates or to a different transport rate in the sites of the esterase activity. Since the steroid moiety is the same for both molecules studied it appears that the hydrolysis and/or the transport rate of the esterified steroids depends on the chemical properties of the substituent at C-21.
Assuntos
Pulmão/metabolismo , Beclometasona/metabolismo , Cromatografia Líquida de Alta Pressão , Humanos , Hidrólise , Técnicas In Vitro , Cinética , Pregnadienodiois/metabolismoRESUMO
Two classes of adenosine binding sites were identified in pig ventricular sarcolemma using 5'-N-[3H]ethylcarboxamideadenosine ([3H]NECA) as radioligand (Bmax = 88 fmol/mg protein, Kd = 28 nM; Bmax = 7100 fmol/mg protein, Kd = 730 nM). Competition experiments indicated that the higher affinity group had the pharmacological characteristics of the A2 adenosine receptors. The lower affinity binding sites may correspond to the A3 adenosine receptors demonstrated in rat brain. Results with the calcium antagonist [3H]nitrendipine suggest that adenosine exerts some of its effects on the heart also through a direct binding to specific calcium-channel subtypes.
Assuntos
Adenosina/metabolismo , Canais de Cálcio/metabolismo , Miocárdio/metabolismo , Sarcolema/metabolismo , Adenosina/análogos & derivados , Adenosina-5'-(N-etilcarboxamida) , Animais , Sítios de Ligação , Ligação Competitiva , Ventrículos do Coração , Miocárdio/ultraestrutura , Nitrendipino/metabolismo , SuínosRESUMO
Human lymphoblastoid Raji cells and mouse hybridoma ascites cells incubated with 20 mM creatine showed significant increases in creatine, creatine phosphate and adenine nucleotide levels and in the energy charge. In human erythrocytes in which no variation of the creatine phosphate-creatine pool was observed because of a very low creatine kinase activity, the adenine nucleotide pool and the energy charge were not modified. These observations suggest not only a relationship among the creatine phosphate-creatine pool, the energy charge and the adenylate pool, but also the possibility to increase the energy charge and the adenylate pool in cells with creatine kinase activity by expanding the creatine phosphate-creatine pool.
Assuntos
Nucleotídeos de Adenina/metabolismo , Creatina/fisiologia , Fosfocreatina/fisiologia , Nucleotídeos de Adenina/sangue , Animais , Linhagem Celular , Creatina/metabolismo , Creatina Quinase/metabolismo , Metabolismo Energético , Eritrócitos/enzimologia , Eritrócitos/metabolismo , Humanos , Hibridomas/citologia , Hibridomas/enzimologia , Hibridomas/metabolismo , Linfócitos/enzimologia , Linfócitos/metabolismo , Camundongos , Fosfocreatina/metabolismoRESUMO
Many researches indicate that some Ca antagonists modulate Ca fluxes not only at the level of the cytoplasmic membrane but also across the sarcoplasmic reticulum. The present study investigates whether certain compounds like propionylcarnitine or acetylcarnitine which have the capacity to influence cardiac activity might interfere with intracellular Ca movements. The results demonstrate that acetylcarnitine and propionylcarnitine do not affect the calcium intracellular movement in sarcoplasmic reticulum.