Role of the Cysteine in R3 Tau Peptide in Copper Binding and Reactivity

Tau is a widespread neuroprotein that regulates the cytoskeleton assembly. In some neurological disorders, known as tauopathies, tau is dissociated from the microtubule and forms insoluble neurofibrillary tangles. Tau comprises four pseudorepeats (R1-R4), containing one (R1, R2, R4) or two (R3) histidines, that potentially act as metal binding sites. Moreover, Cys291 and Cys322 in R2 and R3, respectively, might have an important role in protein aggregation, through possible disulfide bond formation, and/or affecting the binding and reactivity of redox-active metal ions, as copper. We, therefore, compare the interaction of copper with octadeca-R3-peptide (R3C) and with the mutant containing an alanine residue (R3A) to assess the role of thiol group. Spectrophotometric titrations allow to calculate the formation constant of the copper(I) complexes, showing a remarkable stronger interaction in the case of R3C (log K-f = 13.4 and 10.5 for copper(I)-R3C and copper(I)-R3A, respectively). We also evaluate the oxidative reactivity associated to these copper complexes in the presence of dopamine and ascorbate. Both R3A and R3C peptides increase the capability of copper to oxidize catechols, but copper-R3C displays a peculiar mechanism due to the presence of cysteine. HPLC-MS analysis shows that cysteine can form disulfide bonds and dopamine-Cys covalent adducts, with potential implication in tau aggregation process

Solução salina hipertônica aumenta a pressão de perfusão cerebral no transplante do fígado para hepatite fulminante: resultados preliminares

During orthotopic liver transplantation for fulminant hepatic failure, some patients may develop sudden deterioration of cerebral perfusion and oxygenation, mainly due to increased intracranial pressure and hypotension, which are likely responsible for postoperative neurological morbidity and mortality. In the present study, we hypothesized that the favorable effects of hypertonic saline solution (NaCl 7.5%, 4 mL/kg) infusion on both systemic and cerebral hemodynamics, demonstrated in laboratory and clinical settings of intracranial hypertension and hemorrhagic shock resuscitation, may attenuate the decrease in cerebral perfusion pressure that often occurs during orthotopic liver transplantation for fulminant hepatic failure. METHODS: 10 patients with fulminant hepatic failure in grade IV encephalopathy undergoing orthotopic liver transplantation with intracranial pressure monitoring were included in this study. The effect on cerebral and systemic hemodynamics in 3 patients who received hypertonic saline solution during anhepatic phase (HSS group) was examined, comparing their data with historical controls obtained from surgical procedure recordings in 7 patients (Control group). The maximal intracranial pressure and the corresponding mean arterial pressure values were collected in 4 time periods: (T1) the last 10 min of the dissection phase, (T2) the first 10 minutes at the beginning of anhepatic phase, (T3) at the end of the anhepatic phase, and (T4) the first 5 minutes after graft reperfusion. RESULTS: Immediately after hypertonic saline solution infusion, intracranial pressure decreased 50.4%. During the first 5 min of reperfusion, the intracranial pressure remained stable in the HSS group, and all these patients presented an intracranial pressure lower than 20 mm Hg, while in the Control group, the intracranial pressure increased 46.5% (P < 0.001). The HSS group was the most hemodynamically stable; the mean arterial pressure during the first 5 min of reperfusion increased 21.1% in the HSS group and decreased 11.1% in the Control group (P < 0.001). During the first 5 min of reperfusion, cerebral perfusion pressure increased 28.3% in the HSS group while in the Control group the cerebral perfusion pressure decreased 28.5% (P < 0.001). Serum sodium at the end of the anhepatic phase and 3 hours after reperfusion was significantly higher in the HSS group (153.00 &plusmn; 2.66 and 149.00 &plusmn; 1.73 mEq/L) than in the Control group (143.71 &plusmn; 3.30 and 142.43 &plusmn; 1.72 mEq/L), P = 0.003 and P < 0.001 respectively. CONCLUSION: Hypertonic saline solution can be successfully used as an adjunct in the neuroprotective strategy during orthotopic liver transplantation for fulminant hepatic failure, reducing intracranial pressure while restoring arterial blood pressure, promoting sustained increase in the cerebral perfusion pressure.Neste estudo testamos a hipótese de que os efeitos benéficos decorrentes da administração da solução salina hipertônica (NaCl 7,5%, 4 mL/kg) sobre a hemodinâmica sistêmica e cerebral na hipertensão intracraniana e no choque hemorrágico, possam atenuar a diminuição da pressão de perfusão cerebral que freqüentemente acompanha o transplante do fígado para hepatite fulminante. MÉTODO: Foram estudados 10 pacientes com hepatite fulminante em encefalopatia grau IV e monitorização de pressão intracraniana submetidos ao transplante do fígado. A hemodinâmica sistêmica e cerebral de 3 pacientes que receberam solução salina hipertônica durante a fase anepática (Grupo SSH) foi analisada comparando com os dados obtidos de 7 pacientes transplantados anteriormente nas mesmas condições (Grupo Controle). Os valores de pressão intracraniana máxima e a correspondente pressão arterial média foram coletados em quatro tempos: (T1) nos últimos 10 min da fase de disseccão, (T2) nos primeiros 10 minutos da fase anepática, (T3) no final da fase anepática e (T4) nos primeiros 5 min da reperfusão RESULTADO: Imediatamente após a infusão da solução salina hipertônica a pressão intracraniana diminuiu 50,4%. Nos primeiros 5 min da reperfusão a pressão intracraniana no Grupo SSH se manteve estável e todos os pacientes apresentavam pressão intracraniana menor que 20 mmHg enquanto no Grupo Controle a pressão intracraniana aumentou 46,5% (

Hepatite fulminante: estudo dos fatores associados à mortalidade hospitalar de 100 pacientes priorizados para transplante de fígado

Introdução. A despeito dos avanços nos cuidados de terapia intensiva e no transplante de fígado (TF), a hepatite fulminante (HF) ainda hoje apresenta alta taxa de mortalidade. A identificação de fatores prognósticos de maior acurácia deve ajudar a otimizar a priorização dos pacientes em lista de espera para o TF. Objetivo. Avaliar fatores prognósticos de mortalidade hospitalar dos pacientes com HF priorizados para TF. Métodos. Foram estudados retrospectivamente 100 pacientes adultos (78 mulheres, idade média 35,5 ± 14,7 anos) com HF priorizados para TF, em um único centro, de fevereiro de 2002 a junho de 2011. O diagnóstico etiológico foi hepatite viral em 17% dos casos, medicamentosa em 29%, autoimune em 13%, criptogênica em 34% e outras causas em 7%. A indicação do TF foi determinada de acordo com os critérios de O’Grady. Foram avaliados: idade, sexo, etiologia, intervalo icterícia/encefalopatia, intervalo entre a priorização e o TF, grau de encefalopatia, tempo de internação, RNI, fator V, bilirrubina, creatinina, AST, ALT, lactato e Model for End-Stage Liver Disease (MELD). Todos os dados foram coletados do dia da priorização. Resultados. O intervalo entre a priorização e o TF foi de 1,5 dias (0 a 9) e o tempo de internação foi de 18 ± 27 dias. A mortalidade hospitalar foi de 69%. Os pacientes não sobreviventes apresentaram na priorização maior grau de encefalopatia [3 (1 a 4) vs. 2 (1 a 4)], MELD (41 ± 9 vs. 38 ± 7) e lactato (62,2 ± 45,2 vs. 33,9 ± 16,0 mg/dL) quando comparados com os sobreviventes (p&lt;0,05). Dos 100 pacientes, 69% foram submetidos ao TF, os outros 31% morreram antes do TF. Os pacientes não transplantados apresentaram maior grau de encefalopatia [4 (1 a 4) vs. 3 (1 a 4)], MELD (44 ± 8 vs. 38 ± 8), lactato (78,4 ± 48,3 vs. 41,8 ± 30,6 mg/dL) e creatinina (2,60 ± 2,34 vs. 1,55 ± 1,54 mg/dL) quando comparados aos pacientes submetidos ao TF (p&lt;0.05). Conclusão. No momento da priorização para o TF, os pacientes com HF que apresentam condição clínica mais grave, com encefalopatia graus 3 ou 4, insuficiência renal, escores mais elevados de MELD e lactato elevado, têm maior taxa de mortalidade hospitalar mesmo quando submetidos ao TF, indicando pior prognóstico

The reactivity of copper complexes with neuronal peptides promoted by catecholamines and its impact on neurodegeneration

In this review we give an updated outlook of the reactivity of catecholamines, particularly dopamine, and the redox effects produced by their interaction with copper(II) and dioxygen, with emphasis to the extensive studies carried out by our group. The interaction between copper(II) ions and neuronal proteins and peptides can contribute to neurodegeneration because in many cases the peptide fragments contain high affinity binding sites and the resulting complexes exhibit increased redox reactivity. It has become apparent in recent years that the redox reactivity of Cu-peptide complexes can be substantially improved by catecholamines, which are redox reactive molecules by themselves but also relatively good ligands for copper ions. Therefore, the toxic effects of copper dyshomeostasis will be particularly harmful in the brain areas producing and releasing catecholamines, i.e. the axon terminals of the substantia nigra and locus coeruleus. These are the brain regions which become affected in the early stages of Parkinson and Alzheimer's disease, indicating that copper neurotoxicity may contribute to the outset of the diseases. Copper-β-amyloid and copper-prion complexes exhibit the highest redox activity induced by catecholamines; their reactivity is modulated by interaction with membranes, which tend to depress the reactivity unless the peptides interact with each other strengthening the binding of copper(II)

Biochemical and functional markers of lung damage after bleomycin treatment.

Lung function tests, including spirometry, and pulmonary transfer factor for carbon monoxide (TLCO), serum angiotensin-converting enzyme (sACE), serum copper (sCU++) and serum procollagen III peptide (sPIIIP) were measured in 20 patients with metastatic testicular carcinoma, before and after treatment with cisplatin, bleomycin, vinblastine or etoposide. A significant decrease of TLCO, total lung capacity and vital capacity was observed at the end of the treatment. No recovery of pulmonary function had taken place 2 yrs after the last dose of bleomycin. This result suggests that bleomycin-induced lung damage is not completely reversible. Serum angiotensin-converting enzyme, remained unmodified, whilst sPIIIP was found to be significantly increased at the end of chemotherapy, but normal 2 yrs after the completion of chemotherapy. Serum Cu++ showed a tendency to decline. No significant correlation was found between sACE, sCu++ and sPIIIP and lung function tests in the follow-up period. These results question the possibility that these markers could be useful indicators of bleomycin-induced lung damage