RESUMO
Thermal tolerance windows are key indicators of the range of temperatures tolerated by animals and therefore, a measure of resilience to climate change. In the ocean, where ectotherms are immersed, body temperatures are tightly coupled to environmental temperature and species have few options for thermoregulation. However, mobile species do have the ability to orientate towards optimal temperatures and move away from sub-optimal or dangerous temperatures. Escape responses are one such locomotory behavior, which typically manifests as a series of violent flicking movements that move individuals out of dangerous environments. We tested 11 species of Antarctic marine ectotherms, from one of the most stable shallow water marine environments, with an annual temperature range of -2°C to +2°C, that are vulnerable to small degrees of warming. Three species, the clam Laternula elliptica, the sea cucumber Cucumaria georgiana, and the brittlestar Ophionotus victoriae, showed no, or virtually no, escape response to temperature. Escape responses from a further eight species had a median response temperature of 11.2 (interquartile range, 10°C-15.7°C), which is well above current environmental temperatures but close to the range for acute lethal limits of Antarctic marine ectotherms (CTmax range, 17.2°C-26.6°C). This highlights that both acute tolerance limits and escape responses, fall outside current environmental temperatures, but also those predicted for 100s of years in the Southern Ocean. In a warmer Southern Ocean Antarctic fauna may not have the capacity to use temperature to select optimal thermal conditions, which leaves adaptation as a primary mechanism for their persistence.
RESUMO
In this work, a computational framework is presented to compute the time evolution of force constants for a coarse grained (CG) elastic network model along an all-atom molecular dynamics trajectory of a protein system. Obtained via matching distance fluctuations, these force constants represent strengths of mechanical coupling between CG beads. Variation of coupling strengths with time is hence termed the fluctuogram of protein dynamics. In addition to the schematic procedure and implementation considerations, several ways of combining force constants and data analysis are presented to illustrate the potential application of protein fluctuograms. The unique angle provided by the fluctuogram expands the scope of atomistic simulations and is expected to impact upon fundamental understanding of protein dynamics as well as protein engineering technologies.
Assuntos
Simulação de Dinâmica Molecular , Tripsina/química , Animais , Computação Matemática , Conformação Proteica , Ratos , TermodinâmicaRESUMO
There is conflicting evidence in the literature on the etiology of hypogonadism in patients with sickle cell disease (SCD). A cross-sectional study was done to determine whether hypogonadism in male patients with SCD is due to primary testicular failure or secondary pituitary/hypothalamic dysfunction and assess the association between hypogonadism and serum ferritin levels. Hormonal assessment for serum concentrations of testosterone, follicle stimulating hormone (FSH) and luteinizing hormone (LH) was done for 34 men with SCD and their charts were reviewed for relevant clinical variables. Eight men (24%) were classified hypogonadal based on their serum testosterone levels. These men have significantly lower LH (p = 0.001) and FSH (p = 0.01) levels than normogonadal men, indicating a central etiology. There was no significant difference between hypogonadal and normogonadal men with respect to ferritin levels (p = 0.71). Our study indicates a central etiology of hypogonadism in patients with SCD. In this small study ferritin level was not significantly related to hypogonadism.
Assuntos
Anemia Falciforme/complicações , Hipogonadismo/complicações , Adolescente , Adulto , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
According to the empirical literature, there are high rates of borderline personality disorder (BPD) among individuals with formal diagnoses of eating disorders, and high rates of eating disorders among individuals with BPD. In this study, we examined relationships between three eating disorder symptoms (i.e., binge eating, starving oneself, abusing laxatives) and borderline personality symptomatology according to two self-report measures (the borderline personality scale of the Personality Diagnostic Questionnaire-4 and the Self- Harm Inventory) in a sample of psychiatric inpatients (N=126) and in a sample of internal medicine outpatients (N=419). Each individual eating disorder item, as well as a composite score of all three items, demonstrated statistically significant correlations with both measures of borderline personality symptomatology in both samples. In addition, endorsement of all three symptoms was invariably associated with borderline personality symptomatology on both measures. Specific eating disorder symptoms, alone, may predict for borderline personality symptomatology.
Assuntos
Transtorno da Personalidade Borderline/diagnóstico , Transtorno da Personalidade Borderline/epidemiologia , Transtornos da Alimentação e da Ingestão de Alimentos/diagnóstico , Transtornos da Alimentação e da Ingestão de Alimentos/epidemiologia , Adolescente , Adulto , Idoso , Transtorno da Personalidade Borderline/psicologia , Comorbidade , Transtornos da Alimentação e da Ingestão de Alimentos/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Personalidade , Inventário de Personalidade , Escalas de Graduação Psiquiátrica , Inquéritos e QuestionáriosRESUMO
BACKGROUND: Coronary patients resistant to aspirin may have increased risk for ischemic events. Little data were available for patients presenting acutely with chest pain. METHODS AND RESULTS: We used the VerifyNow Aspirin to determine aspirin responsiveness of 314 patients regularly taking aspirin 75-300 mg daily for >or=4 weeks who presented with suspected acute coronary syndrome in Emergency Department. Aspirin resistance was defined as an aspirin reaction unit (ARU) >or=550, and the clinical team was blinded to the ARU reading. The pre-specified study endpoints were the diagnosis of acute myocardial infarction (AMI) for the index admission and major adverse cardiac events including cardiovascular death or recurrent acute coronary syndrome requiring hospitalization within 6 months. Aspirin resistance was noted in 30 (9.6%) patients. There was no difference in the diagnosis of AMI for the index presentation (3/30, 10% vs. 25/284, 8.8%, P = 0.91). Among the 312 hospital survivors, aspirin resistant patients had increased adverse events over 6 months with an overall hazard ratio of 10.0 [95% confidence interval (CI) 4.6-22.0]. After adjusted for elevated Troponin-T, the only confounder in the model, the hazard ratio was 11.1 (95% CI 4.7-26.0). Results were similar in patients treated only medically without revascularization (adjusted hazard ratio 12.1, 95% CI 4.7-26.4). The increased events were observed both from discharge to 30 days and from 30 days to 6 months. CONCLUSION: Aspirin resistance occurs in approximately 10% of patients presenting with suspected acute coronary syndrome and is associated with adverse cardiac events.
Assuntos
Síndrome Coronariana Aguda/tratamento farmacológico , Aspirina/uso terapêutico , Resistência a Medicamentos , Inibidores da Agregação Plaquetária/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Métodos Epidemiológicos , Feminino , Humanos , Pessoa de Meia-Idade , Testes de Função Plaquetária , Troponina T/sangueRESUMO
OBJECTIVE: This study aimed to determine whether the plasma levels of matrix metalloproteinase-9 (MMP-9) or tissue inhibitor of metalloproteinases-1 (TIMP-1) were altered in patients with a history of symptomatic in-stent restenosis (ISR). METHODS AND RESULTS: A group of 158 patients with a history of ISR were compared with 128 symptom-free patients. Plasma samples and a detailed risk factor history were collected. Plasma samples were analyzed for pro-MMP-9 and latent MMP-9 and active MMP-9, latent MMP-3, and TIMP-1. Several variables were associated with ISR, including index coronary disease extent and severity (number of diseased vessels and American College of Cardiology/American Heart Association lesion classification), number, diameter, and total length of stent(s) inserted, and plasma high-density lipoprotein cholesterol. Plasma active MMP-9 (odds ratio, 1.96; 95% CI, 1.43 to 2.69) showed independent risk association with ISR. Patients with multiple sites of ISR had significantly higher levels of active MMP-9 compared with patients with only a single ISR lesion or no ISR. CONCLUSIONS: Plasma active MMP-9 levels may be a useful independent predictor of bare metal stent ISR.
Assuntos
Reestenose Coronária/sangue , Metaloproteinase 9 da Matriz/sangue , Stents , Inibidor Tecidual de Metaloproteinase-1/sangue , Idoso , HDL-Colesterol/sangue , Angiografia Coronária , Reestenose Coronária/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Índice de Gravidade de DoençaRESUMO
AIMS: To compare lipoprotein risk factors for cardiovascular disease (CVD) in patients with type 2 diabetes mellitus (DM) treated with a sulphonylurea (SU) compound only, metformin (MET) only, or combined SU + MET. METHODS: The study population consisted of 62 patients with type 2 DM, whose antihyperglycaemic treatment program had been stable for at least 3 months, divided into three groups: 26 patients in the SU group, 17 patients in the MET group and 19 patients in the SU + MET group. None of the patients were taking lipid-lowering drugs. Fasting venous blood samples were taken to measure concentrations of glucose, total cholesterol, triglycerides (TG), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C) and remnant lipoprotein-cholesterol (RLP-C) as well as for determination of LDL particle diameter. RESULTS: The three groups were similar in terms of age, gender, body mass index and fasting plasma glucose concentrations. Total cholesterol concentrations were significantly lower (p < 0.05 for trend) in those treated with SU + MET as compared with the other two groups. However, there were no significant differences between the three groups in their plasma concentrations of TG, LDL-C, HDL-C or RLP-C; furthermore, the proportion of individuals within each treatment group with small LDL particle diameter was also not different. CONCLUSIONS: The lipoprotein profile of patients with type 2 DM, matched for level of fasting hyperglycaemia, was similar irrespective of treatment with SU alone, MET alone or SU + MET. Thus, we could not identify any changes in lipoprotein metabolism that could account for differences in risk of CVD as a function of treatment.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Angiopatias Diabéticas/prevenção & controle , Hipoglicemiantes/uso terapêutico , Lipoproteínas/sangue , Glicemia/análise , Colesterol/sangue , Estudos Transversais , Diabetes Mellitus Tipo 2/sangue , Angiopatias Diabéticas/sangue , Angiopatias Diabéticas/etiologia , Quimioterapia Combinada , Feminino , Humanos , Masculino , Metformina/uso terapêutico , Pessoa de Meia-Idade , Fatores de Risco , Compostos de Sulfonilureia/uso terapêuticoAssuntos
Hipotireoidismo/terapia , Adulto , Idoso , Arteriosclerose/etiologia , Feminino , Terapia de Reposição Hormonal , Humanos , Hiperlipidemias/etiologia , Hipotireoidismo/complicações , Hipotireoidismo/diagnóstico , Masculino , Pessoa de Meia-Idade , Tireotropina/sangue , Hormônio Liberador de Tireotropina/farmacologia , Tiroxina/uso terapêuticoRESUMO
An extremely ill patient, with Cushing's syndrome caused by an ACTH-secreting pituitary macroadenoma, experienced complications of end-stage cardiomyopathy, profound psychosis, and multiple metabolic disturbances. Initially treated unsuccessfully by a combination of conventional surgical, medical, and radiotherapeutic approaches, he responded dramatically to high-dose long-term mifepristone therapy (up to 25 mg/kg x d). Treatment efficacy was confirmed by the normalization of all biochemical glucocorticoid-sensitive measurements, as well as by the significant reversal of the patient's heart failure, the resolution of his psychotic depression, and the eventual unusual return of his adrenal axis to normal. His 18-month-long mifepristone treatment course was notable for development of severe hypokalemia that was attributed to excessive cortisol activation of the mineralocorticoid receptor, which responded to spironolactone administration. This case illustrates the efficacy of high-dose long-term treatment with mifepristone in refractory Cushing's syndrome. The case also demonstrates the potential need for concomitant mineralocorticoid receptor blockade in mifepristone-treated Cushing's disease, because cortisol levels may rise markedly, reflecting corticotroph disinhibition, to cause manifestations of mineralocorticoid excess.
Assuntos
Síndrome de Cushing/tratamento farmacológico , Mifepristona/uso terapêutico , Hormônio Adrenocorticotrópico/sangue , Negro ou Afro-Americano , Densidade Óssea , Encéfalo/patologia , California , Colesterol/sangue , Síndrome de Cushing/fisiopatologia , Síndrome de Cushing/psicologia , Transtorno Depressivo/etiologia , Hemoglobinas Glicadas/análise , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/etiologia , Antagonistas de Hormônios/uso terapêutico , Humanos , Hidrocortisona/sangue , Imageamento por Ressonância Magnética , Masculino , Entrevista Psiquiátrica Padronizada , Pessoa de Meia-Idade , Osteocalcina/sangue , Função Ventricular EsquerdaRESUMO
This case presents a 34-year-old man who had a huge parasagittal meningioma. Initial treatment consisted of preoperative external carotid artery embolization and partial tumor resection. During the resection, we found that the tumor invaded the adjacent calvarium, and due to massive hemorrhage, total removal of the tumor was impossible. The patient was treated with intraoperative radiation therapy (IORT) (25 Gy via 16 MeV) as an adjunctive therapy. Eight months after IORT, we were able to remove the tumor completely without surgical difficulties. IORT can be considered an useful adjunctive therapy for the superficially located, huge, and highly vascular meningioma.
Assuntos
Cuidados Intraoperatórios , Neoplasias Meníngeas/radioterapia , Meningioma/radioterapia , Neoplasias Vasculares/radioterapia , Adulto , Humanos , Imageamento por Ressonância Magnética , Masculino , Neoplasias Meníngeas/patologia , Neoplasias Meníngeas/cirurgia , Meningioma/patologia , Meningioma/cirurgia , Neoplasias Vasculares/patologia , Neoplasias Vasculares/cirurgiaRESUMO
Glycosylphosphatidylinositol (GPI)-anchored membrane proteins are proposed to interact preferentially with glycosphingolipids and cholesterol to form microdomains, which may play an important role in apical targeting and signal transduction. The objective of the present study was to investigate the interaction of the GPI-anchored protein Thy-1 with phospholipids and a glycosphingolipid. Purified Thy-1 was reconstituted into lipid bilayer vesicles of dimyristoyl-phosphatidylcholine (DMPC) alone or in combination with galactosylceramide (GC). The ability of Thy-1 to perturb the gel to a liquid-crystalline phase transition of DMPC was examined by differential scanning calorimetry. As the mole fraction of Thy-1 increased, the phase transition enthalpy, deltaH, declined. Analysis indicated that each molecule of Thy-1 perturbed over 50 phospholipids, suggesting that, in addition to the anchor insertion into the bilayer, the protein itself may interact with the membrane surface. Inclusion of 5% w/w GC in the bilayer resulted in a striking change in the interaction of Thy-1 with phospholipids. At low Thy-1 content, there was a reduction in the phase transition temperature and an increase in phospholipid cooperativity, suggesting the formation of Thy-1/GC-enriched domains. DeltaH initially decreased with increasing Thy-1 content of the bilayer; however, at higher Thy-1 mole ratios, deltaH rose again. These results are interpreted in terms of a model whereby, at low protein:lipid mole ratios, Thy-1 preferentially sequesters GC to form enriched microdomains. At high protein:lipid mole ratios, Thy-1 may alter its conformation in response to steric crowding within these domains such that its interaction with the bilayer surface is reduced.
Assuntos
Galactosilceramidas/química , Glicosilfosfatidilinositóis/química , Lipídeos de Membrana/química , Fosfolipídeos/química , Western Blotting , Varredura Diferencial de Calorimetria , Linhagem Celular , Cromatografia de Afinidade , Eletroforese em Gel de Poliacrilamida , Glicosilfosfatidilinositóis/isolamento & purificaçãoRESUMO
P-glycoprotein-mediated multidrug resistance can be reversed by the action of a group of compounds known as chemosensitizers. The interactions with P-glycoprotein of two novel hydrophobic peptide chemosensitizers (reversins 121 and 205) have been studied in model systems in vitro, and in a variety of MDR1-expressing intact tumor cells. The reversins bound to purified P-glycoprotein with high affinity (77-154 nM), as assessed by a quenching assay using fluorescently labeled purified protein. The peptides modulated P-glycoprotein ATPase activity in Sf9 insect cell membranes expressing human MDR1, plasma membrane vesicles from multidrug-resistant cells, and reconstituted proteoliposomes. Both peptides induced a large stimulation of ATPase activity; however, higher concentrations, especially of reversin 205, led to inhibition. This pattern was different from that of simple linear peptides, and resembled that of chemosensitizers such as verapamil. In both membrane vesicles and reconstituted proteoliposomes, 1-2 microM reversins were more effective than cyclosporin A at blocking colchicine transport. Reversin 121 and reversin 205 restored the uptake of [3H]daunorubicin and rhodamine 123 in MDR1-expressing cells to the level observed in the drug-sensitive parent cell lines, and also effectively inhibited the extrusion of calcein acetoxymethyl ester from intact cells. In cytotoxicity assays, reversin 121 and reversin 205 eliminated the resistance of MDR1-expressing tumor cells against MDR1-substrate anticancer drugs, and they had no toxic effects in MDR1-negative control cells. We suggest that peptides of the reversin type interact with the MDR1 protein with high affinity and specificity, and thus they may be good candidates for the development of MDR1-modulating agents to sensitize drug resistance in cancer.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Membrana Celular/efeitos dos fármacos , Resistência a Múltiplos Medicamentos , Resistencia a Medicamentos Antineoplásicos , Oligopeptídeos/farmacologia , Peptídeos/metabolismo , Adenosina Trifosfatases/metabolismo , Animais , Azidas , Transporte Biológico/efeitos dos fármacos , Células CHO , Membrana Celular/metabolismo , Colchicina , Cricetinae , Daunorrubicina , Di-Hidropiridinas , Corantes Fluorescentes , Humanos , Marcadores de Fotoafinidade , Rodamina 123 , Células Tumorais CultivadasRESUMO
The equine embryonic capsule, an acellular covering that envelops the conceptus during the second and third weeks of pregnancy, is composed of mucin-like glycoproteins. Its structure is consistent with a dual role during early pregnancy: protection of the conceptus, and communication between the embryo and the mother. Loss of sialic acid from the capsular glycoproteins at day 16 correlates with the time of "fixation," or loss of conceptus mobility throughout the uterine horns. This study investigated how the structure of the capsule is linked to the maintenance of pregnancy. Six pregnancies, confirmed by ultrasound, were terminated by prostaglandin injection on day 14, prior to the time of embryo fixation. These "defective" conceptuses were collected at day 17, and the structure and molecular properties of their capsules were compared to those of day 17 conceptuses collected from 5 normal pregnancies. Defective capsules were not significantly different from normal capsules in terms of dry weight, amino acid composition, and content of neutral and amino sugars. However, defective capsules failed to show the loss of sialic acid normally occurring around the time of embryo fixation. Analysis of the capsular mucins following trypsin digestion was carried out by radioactive labeling with 3H on sialyl-oligosaccharides and 125I on tyrosine residues, followed by fast protein liquid chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Differences in the trypsin fragmentation patterns indicated increased susceptibility of the defective capsules to proteolysis. We conclude that there is a temporal association between desialylation of the equine capsule and embryonic survival, and that failure to desialylate alters the properties of the capsule.
Assuntos
Aborto Animal , Membranas Extraembrionárias/química , Ácido N-Acetilneuramínico/análise , Prostaglandinas/farmacologia , Aborto Induzido/veterinária , Animais , Autorradiografia , Cromatografia Líquida de Alta Pressão , Eletroforese em Gel de Poliacrilamida , Feminino , Cavalos , GravidezRESUMO
P-Glycoprotein functions as an ATP-driven active efflux pump for many natural products and chemotherapeutic drugs. Hydrophobic peptides have been shown to block drug uptake by P-glycoprotein, indicating that they might be transport substrates. The present study examines the interaction of the synthetic peptide series NAc-LnY-amide with the multidrug transporter. Several peptides in this series caused up to 3.5-fold enhancement of colchicine accumulation in membrane vesicles from multidrug resistant (MDR) cells, which suggests the existence of novel interactions between the binding sites for peptides and drug. Peptides did not stimulate vinblastine transport, which was inhibited as expected for competing substrates. These peptides displayed modest stimulatory effects on the ATPase activity of P-glycoprotein. None blocked azidopine photoaffinity labelling, showing that they probably occupy a binding site separate from that for the drug. Studies with 125I-labelled NAc-LLY-amide showed that it was transported by P-glycoprotein in both membrane vesicles and reconstituted proteoliposomes. Uptake of the peptide was rapid, saturable, osmotically sensitive and occurred against a concentration gradient. The enhancing effect of NAc-LLY-amide on colchicine transport was reciprocated, i.e. colchicine greatly increased the transport of labelled peptide by P-glycoprotein. Peptide transport was also modulated, both positively and negatively, by other MDR spectrum drugs. It is concluded that linear hydrophobic peptides are indeed transported by P-glycoprotein, and some have interactions with drug substrates that result in mutual stimulation of transport.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Oligopeptídeos/metabolismo , Oligopeptídeos/farmacologia , Marcadores de Afinidade , Animais , Azidas , Transporte Biológico/efeitos dos fármacos , Células CHO , Colchicina/metabolismo , Colchicina/toxicidade , Cricetinae , Di-Hidropiridinas , Resistência a Múltiplos Medicamentos , Cinética , Leupeptinas/farmacologia , Oligopeptídeos/síntese química , Especificidade por Substrato , Vimblastina/metabolismoRESUMO
Glycophorin A was reconstituted into large unilamellar vesicles of egg phosphatidylcholine by detergent dialysis. The observed overall rate of Sendai virus fusion increased approximately 4-fold between 0 and 0.006 mol % glycophorin, roughly proportional to the glycophorin content. However, no further increase in rate was observed at 0.02 mol % glycophorin. Treatment of reassembled glycophorin-liposomes with neuraminidase resulted in a significant decrease in the percent of viral fusion, confirming that the presence of sialic acid residues on glycophorin is essential for its role as a receptor. The sialic acid-containing glycolipid, the ganglioside GD1a, was also incorporated into phosphatidylcholine liposomes, either in addition to or in place of glycophorin A. Comparing, on the basis of sialic acid content, liposomes containing either glycophorin or GD1a, comparable rates and extents of fusion were found. However, on a molar basis glycophorin is much more effective. It was found that the addition of GD1a to glycophorin-containing liposomes only slightly increased the rate of fusion. This was largely due to an increase in the percent of virions capable of fusing.
Assuntos
Glicoforinas/metabolismo , Vírus da Parainfluenza 1 Humana/metabolismo , Receptores Virais/metabolismo , Gangliosídeos/farmacologia , Glicoforinas/farmacologia , Lipossomos/metabolismo , Fusão de Membrana , Neuraminidase/metabolismo , Tamanho da Partícula , Fosfatidilcolinas/metabolismoRESUMO
Ten brain tumor patients underwent wide resection of the tumor followed by Intraoperative Radiation Therapy (IORT) at the first surgery or at the second salvage surgery after failure of conventional external beam irradiation. Two patients(1 meningioma, 1 glioblastoma multiforme) were treated at the first surgery and 8 patients(3 anaplastic astrocytoma, 3 glioblastoma multiforme, 1 meningioma, 1 gliosarcoma) were treated after salvage surgery. The IORT doses were ranged from 15-25 Gy depending on the tumor volume and previous radiation therapy. The neurological status(Karnofsky performance status) was improved in 4 cases, not changed in 6 cases after IORT. There were several complications after IORT; radiation necrosis, communicating hydrocephalus, wound infection, and abnormal CT findings such as diffuse low density area in an around operation site. The radiation necrosis was confirmed by operation in a recurrent meningioma patient 12 months after IORT. At follow-up, ranging from 1 to 16 months, there was no deaths. Based on our limited experiences, the IORT might be one of the adjuvant therapeutic modalities especially for the malignant brain tumors and unresectable huge meningioma.
Assuntos
Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/cirurgia , Adulto , Astrocitoma/radioterapia , Astrocitoma/cirurgia , Neoplasias Encefálicas/patologia , Terapia Combinada , Feminino , Glioblastoma/radioterapia , Glioblastoma/cirurgia , Gliossarcoma/radioterapia , Gliossarcoma/cirurgia , Humanos , Cuidados Intraoperatórios , Masculino , Meningioma/radioterapia , Meningioma/cirurgia , Pessoa de Meia-Idade , Terapia de SalvaçãoRESUMO
The present study was performed to investigate the relationship between the concentrations of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) and the CT images in 23 cases of chronic subdural hematomas (SDHs). The concentrations of t-PA and PAI-1 were quantified by enzyme-linked immunosorbent assay (ELISA). Chronic SDHs were divided into five groups according to their appearance on computed tomography: high-density (n = 4), isodensity (n = 8), low-density (n = 5), mixed-density (n = 3), layering (n = 3) types. The volume of hematoma was measured with an image analyzing software program. The concentrations of t-PA were higher in layering (41.2 +/- 0.3 ng/ml, mean +/- standard error of the mean) and high-density (40.0 +/- 1.1 ng/ml) types compared to those of low-density (23.3 +/- 4.1 ng/ml) and iso-density (25.1 +/- 3.7 ng/ml) types. The concentrations of PAI-1 were lower in layering (95.9 +/- 1.0 ng/ml) and high-density (103.4 +/- 34.5 ng/ml) types compared to that of low-density (192.5 +/- 2.6 ng/ml) type. So the ratio between t-PA and PAI-1 (t-PA/PAI) was greater in layering and high-density types. The volume of hematoma was larger in mixed-density and layering types but statistically insignificant. These results presumably suggest that the ratio between t-PA and PAI concentration may contribute to the pathogenesis of the chronic SDH.
Assuntos
Hematoma Subdural/metabolismo , Inibidor 1 de Ativador de Plasminogênio/análise , Ativador de Plasminogênio Tecidual/análise , Adulto , Idoso , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios XRESUMO
P-Glycoprotein (Pgp) was isolated from CHRC5 membranes by selective detergent extraction and further purified by lentil lectin affinity chromatography. The purified product displayed a very high basal ATPase activity (1.65 mumol/min per mg protein in the absence of added drugs or lipids) with an apparent Km for ATP of 0.4 mM. There was no evidence of cooperativity, suggesting that the two ATP sites operate independently of each other. Pgp ATPase activity was stimulated by verapamil, trifluoperazine and colchicine, and inhibited by daunomycin and vinblastine. All drugs and chemosensitizers acted as mixed activators or inhibitors, producing changes in both the Vmax of the ATPase and the Km for ATP. ADP competitively inhibited Pgp ATPase, with a Ki of 0.2 mM. The macrolide antibiotics bafilomycin A1, concanamycin A and concanamycin B, inhibited Pgp ATPase at concentrations of 0.1-10 microM, and at an inhibitor:protein stoichiometry of 0.65-1.0 mumol/mg protein, which is at the low end of the range characteristic of P-type ATPases. Pgp ATPase was relatively selective for adenine nucleotides. Several phospholipids stimulated Pgp ATPase activity in a dose-dependent manner, whereas others produced inhibition. Metabolic labelling showed that the endogenous phospholipids associated with purified Pgp consisted largely of phosphatidylethanolamine and phosphatidylserine, with only a small amount of phosphatidylcholine. 32P-Labelling studies indicated that purified Pgp was partially phosphorylated. It can be concluded that Pgp is a constitutively active, adenine nucleotide-specific ATPase whose catalytic activity can be modulated by both drugs and phospholipids.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Adenosina Trifosfatases/metabolismo , Resistência a Múltiplos Medicamentos , Macrolídeos , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/antagonistas & inibidores , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/química , Difosfato de Adenosina/farmacologia , Adenosina Trifosfatases/antagonistas & inibidores , Animais , Antibacterianos/farmacologia , Células CHO , Cricetinae , Cinética , Fosfolipídeos/química , FosforilaçãoRESUMO
Gangliosides are potent immunosuppressive agents in vitro, and gangliosides shed from tumours in vivo may play an important role in the escape of tumours from immune destruction. We have investigated the effect of gangliosides on interleukin-4 (IL-4)-mediated processes in the murine helper T-cell line HT-2. Various gangliosides inhibited IL-4-stimulated DNA synthesis in HT-2 with IC50 values in the range 26-60 micrograms/ml. However, the proliferation of four lymphokine-independent cell lines was unaffected by 500 micrograms/ml gangliosides, as was the IL-1-stimulated secretion of IL-2 by EL-4 NOB-1 cells. Gangliosides were highly effective inhibitors when added to G0-G1-synchronized HT-2 cells during the first 6 hr after IL-4 stimulation, indicating that they act early in the IL-4 signalling pathway. High levels of exogenous IL-4 completely reversed inhibition of proliferation by gangliosides, which suggests that gangliosides compete with cellular IL-4 receptors for available lymphokine. Receptor-binding experiments confirmed that gangliosides blocked binding of [125I]IL-4 to receptors on intact HT-2 cells in a dose-dependent fashion. Gel-filtration fast protein liquid chromatography (FPLC) demonstrated that [125I]IL-4 co-eluted with ganglioside micelles after co-incubation before chromatography, and an overlay technique showed that IL-4 bound efficiently to gangliosides on thin-layer chromatography plates. Taken together, these results indicate that gangliosides act as potent suppressors of IL-4-dependent processes in lymphocytes, and that their mechanism of action involves direct interaction with IL-4, thus preventing IL-4 binding to high-affinity IL-4 receptors. This information helps to explain the diverse immunosuppressive actions reported for gangliosides, both in vitro and in vivo.
Assuntos
Gangliosídeos/farmacologia , Tolerância Imunológica/efeitos dos fármacos , Interleucina-4/antagonistas & inibidores , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Animais , Ligação Competitiva , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Relação Dose-Resposta Imunológica , Gangliosídeos/metabolismo , Humanos , Interleucina-1/imunologia , Interleucina-4/imunologia , Interleucina-4/metabolismo , Camundongos , Micelas , Receptores de Interleucina/metabolismo , Receptores de Interleucina-4 , Transdução de Sinais/efeitos dos fármacos , Fatores de TempoRESUMO
Deuterium nuclear magnetic resonance spectroscopy was used to investigate the phase equilibria, and the temperature and concentration dependences of the phospholipid hydrocarbon chain order, of mixtures of glycophorin in dimyristoylphosphatidyl-choline. In the fluid phase it is found that the protein has only a slight effect on the first moment of the 2H spectrum, which for perdeuterated chains is a direct measure of the average chain orientational order. However, analysis of the rate of change of the first moment with respect to protein concentration, at different temperatures within the fluid phase, shows that at a molar protein concentration of about 0.0295 +/- 0.01, the lipid chain order (or M1) is essentially independent of temperature. At this concentration the chain order is determined by the lipid's interaction with the protein and one can conclude that about 34 (+/- 12) lipids are required to solvate the protein. At higher lipid concentrations these lipids are freely exchanging, on the NMR time scale, with the other lipids in the bilayer. At glycophorin concentrations below about 1 mol% there is a two-phase coexistence region at temperatures below the pure lipid's chain melting transition. The boundary between the fluid phase and this two-phase region curves downwards (is concave downwards), whereas the boundary between the two-phase region and the gel phase, while naturally occurring at lower temperatures than the upper boundary, is concave upwards. As a consequence the protein partitions preferentially into the fluid phase. This behaviour is similar to that observed in a number of other protein/lipid and peptide/lipid mixtures where it was suggested that those systems may have been close to a critical mixing point and some characteristics of a continuous phase change were noted. Indeed, at glycophorin concentrations near and above 1 mol% there are indications that the phase behaviour becomes more complex, suggesting the presence of significant protein/protein interactions and that this system may be close to a critical point.