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1.
Plast Reconstr Surg Glob Open ; 9(11): e3911, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34804760

RESUMO

Oncological breast surgeries, classified as breast conserving surgery, oncoplastic surgery, and mastectomies (standard or with tissue sparing and reconstruction), are burdened with an overall complication rate up to 33%. Aquacel Ag Surgical is a combined hydrofiber-hydrocolloids dressing. The aim of this study is to evaluate the incidence of surgical site complications in patients presenting with three or more risk factors (or two, of which at least one classified as "high risk"), undergoing breast cancer surgery with/without reconstruction, comparing advanced (Aquacel Ag Surgical) with traditional dressing. METHODS: This is a retrospective, monocentric, case-control study based at the breast unit of the Città della Salute e della Scienza Hospital of Turin, Italy. Forty-two patients who underwent breast surgeries and met the inclusion criteria were enrolled, from February 1 to July 31, 2018. The primary endpoint was comparing the incidence of surgical site complications (skin alterations, infection, and wound dehiscence) in the two groups. The secondary endpoints were evaluating patient's quality of life, aesthetic outcomes, and compliance to the dressings. RESULTS: The distribution of risk factors at the baseline between the two groups was balanced, without statistically significant differences. Wound complications' incidence at 1 week was lower in the advanced dressing group (P = 0.015). On the bivariate descriptive analysis, advanced dressing proved to be easier to remove for the operator (P = 0.026). The aesthetic outcomes vouched for better scores in the advanced dressing group. CONCLUSION: In the presented study Aquacel Ag Surgical dressing reduces surgical site complications in the first week after surgery in patients affected by three or more risk factors (or two with at least one classified as "high risk").

2.
Animals (Basel) ; 10(5)2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32370008

RESUMO

There is interest in identifying natural products capable of manipulating rumen microbial activity to develop new feed additives for ruminant nutrition as a strategy to reduce methane. Two trials were performed using the in vitro gas production technique to evaluate the interaction of substrate (n = 5) and additive (n = 6, increasing doses: 0, 0.3, 3, 30, and 300 µL/L of essential oils-EO-of Lippia turbinata or Tagetes minuta, and monensin at 1.87 mg/L). The two EO utilized were selected because they differ markedly in their chemical composition, especially in the proportion of oxygenated compounds. For both EO, the interaction between the substrate and additive was significant for all variables; however, the interaction behaved differently for the two EO. Within each substrate, the response was dose-dependent, without effects at a low level of EO and a negative outcome at the highest dose. The intermediate dose (30 µL/L) inhibited methane with a slight reduction on substrate digestibility, with L. turbinata being more effective than T. minuta. It is concluded that the effectiveness of the EO to reduce methane production depends on interactions between the substrate that is fermented and the additive dose that generates different characteristics within the incubation medium (e.g., pH); and thus, the chemical nature of the compounds of the EO modulates the magnitude of this response.

4.
Eur Rev Med Pharmacol Sci ; 16(10): 1346-54, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23104650

RESUMO

Aripiprazole is an atypical antipsychotic used for schizophrenia, manic and mixed episodes associated with bipolar I disorder and as adjunctive therapy for major depressive disorder. It functions as a partial agonist at dopamine D2 and 5-HT1A receptors, and as an antagonist at the 5-HT2A receptor. The most recent results obtained from scientific research showed that dopaminergic mechanisms are involved in motivation, reward, and reinforcement of substance abuse. The use of aripiprazole and partial dopamine agonists could represent a novel strategy for normalizing dopamine neurotransmission. Many studies in the last few years have highlighted aripiprazole as a potential candidate for the treatment of different types of substance dependence. This review aims to describe recent scientific research using aripiprazole in different substance abuse disorders (i.e., alcoholism, cocaine, amphetamine and nicotine use). Furthermore, the efficacy of aripiprazole compared to other pharmacological therapies will be described. Given the low number of studies, the frequent absence of placebo or active comparators, and the low statistical power of the studies, a clear conclusion about the use of aripiprazole in alcohol/substance dependence cannot be drawn. Therefore, we suggest the need for further studies, preferably randomized and placebo-controlled.


Assuntos
Alcoolismo/tratamento farmacológico , Antipsicóticos/uso terapêutico , Piperazinas/uso terapêutico , Quinolonas/uso terapêutico , Transtornos Relacionados ao Uso de Substâncias/tratamento farmacológico , Aripiprazol , Transtornos Relacionados ao Uso de Cocaína/tratamento farmacológico , Humanos , Tabagismo/tratamento farmacológico
5.
Res Vet Sci ; 83(1): 109-15, 2007 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17156803

RESUMO

This paper describes the histopathological features and cellular distribution of T lymphocytes (CD3), B cells (CD79), follicular dendritic cells (FDC) and macrophages (alpha-1-antitrypsin, lysozyme) in lymphoid aggregates (Kisselev nodules) found in the lung, kidney and liver of wild boar (Sus scrofa L.). The distribution of immunoreactive cells, tested for antibodies, was similar to that found in the cortex of lymph nodes: lymphoid follicles with germinal centers mainly consisting of CD79+ B cells with sparse interfollicular tissue (CD3+ T lymphocytes). This finding and the association of these structures with helminthic infections suggests that local humoral immunity is central to the organism's response to parasitic challenge. The presence of follicular dendritic cells confirms the high degree of organization of these lymphoid-like structures. The role of other pathogenic factors and the induction of chronic inflammatory reaction in these ectopic lymphoid sites is also discussed.


Assuntos
Coristoma/veterinária , Imuno-Histoquímica/veterinária , Tecido Linfoide/patologia , Sus scrofa , Doenças dos Suínos/diagnóstico , Animais , Coristoma/diagnóstico , Rim/patologia , Fígado/patologia , Pulmão/patologia
6.
Ann Oncol ; 15(11): 1684-90, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15520072

RESUMO

BACKGROUND: Once-weekly dosing of recombinant human erythropoietin (rhEPO) in patients with myelodysplastic syndromes (MDS) has not been investigated thoroughly. We performed a clinical trial to evaluate the effects of this new dosing regimen in patients with MDS who were unresponsive to the conventional three-times-weekly schedule. PATIENTS AND METHODS: Forty-eight patients with low- or intermediate-risk MDS were enrolled in a 12-week study. rhEPO alpha (rhEPOalpha) was administered once-weekly by subcutaneous injection with a starting dose of 40,000 U fixed dose. The drug dosage was increased to 60,000 U fixed dose if after 6 weeks there was no or suboptimal erythroid response. RESULTS: Clinically significant responses were seen in 13 (27%) patients, with 11 improving their response after dose escalation of rhEPOalpha. Only one patient (case 23) maintains a response after a follow-up period of 14 months. All other patients had responses lasting between 10 and 43 weeks, with a median time to relapse of 20 weeks. Treatment was well tolerated, with no relevant adverse events. Response to therapy was associated with significantly higher concentrations of circulating erythroid blast-forming units and a decrease of the bone marrow fraction of apoptic CD34+ cells. CONCLUSIONS: Once-weekly rhEPOalpha therapy results in an improvement of erythropoiesis in a subset of MDS patients who are unresponsive to conventional dosing, and may act by inhibiting apoptosis of erythroid precursors. These results warrant further investigation of this dosing regimen either alone or in combination with other agents.


Assuntos
Eritropoetina/administração & dosagem , Síndromes Mielodisplásicas/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Antígenos CD34/análise , Apoptose/efeitos dos fármacos , Relação Dose-Resposta a Droga , Esquema de Medicação , Eritropoetina/uso terapêutico , Feminino , Citometria de Fluxo , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Proteínas Recombinantes , Resultado do Tratamento
7.
Minerva Cardioangiol ; 50(1): 21-7, 2002 Feb.
Artigo em Italiano | MEDLINE | ID: mdl-11830715

RESUMO

BACKGROUND: The aim of this study is to evaluate diagnostic methods, indications and surgical technique in SEPS procedure and to analyze short term results. METHODS: Eighteen patients affected by chronic venous insufficiency (CVI) have been analyzed. According to NAVS (North American Vascular Society) classification three patients were included in class 6 (C6), 3 (C5), 6 (C4), 2 (C3) and 4 (C2). From 2 to 5 selective subfascial endoscopic ligation of perforator veins, especially I and II Cockett perforator veins' were performed. In 7 cases, total stripping of the great (6) or less (1) saphenous vein was associated with SEPS procedure. After the operation, an elastic bandage of the lower limbs was performed and a medical treatment with LMVH was started. RESULTS: In 6 patients of the C2 and C3 groups, neither recurrence or pathological reflux were observed at clinical examination and at color duplex. In 12 patients of C4, C5 and C6 groups a reduction of the perimalleolar oedema was observed. In the last 3 patients, with leg ulceration, a resolution of the lesion in 2 cases, and a reduction in diameter in the last one, were observed. CONCLUSIONS: SEPS is particularly advised in those patients belonging to C5 and C6 groups, especially in presence of leg ulceration. This operations is suggested also in patients with CVI and incontinence of perforator veins detected by at color duplex. This diagnostic investigation seems to be adequate in the diagnosis of CVI and in the mapping of perforator veins of the leg.


Assuntos
Angioscopia/métodos , Insuficiência Venosa/diagnóstico , Insuficiência Venosa/cirurgia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo
8.
Minerva Cardioangiol ; 49(6): 383-7, 2001 Dec.
Artigo em Italiano | MEDLINE | ID: mdl-11733733

RESUMO

BACKGROUND: The aim of surgical therapy of varicose veins is the elimination of reflux from the deep to superficial system at the saphenous crosse and perforant vessel and conservation of the superficial venous system due to possible surgical procedures for arterial revascularization. This latter condition leads to an extension of indications for short stripping procedures, although the venous distal segment may undergo hypoplastic degeneration not compatible for revascularization purposes. Another important reason is the minor incidence of neurologic complication due to saphenous nerve lesion which may occur during long saphenous stripping. METHODS: From January 1994 to June 1999, we considered 233 patients (182 women, 51 men); 180 cases underwent long saphenous stripping procedures, whereas 53 a short stripping of GSV. The incidence of neurologic complications of the saphenous nerve were recorded in 11.6% of the patients treated with the standard procedure, whereas no such complication was observed in all cases treated with the short stripping procedure. RESULTS: ECD follow-up performed for a period of three months from the surgical procedure revealed the patency of the residual saphenous vein, with a minimum diameter of 3 mm, in 28 patients (56.6%). CONCLUSIONS: Our opinion is to extend the indication for short stripping of the saphenous vein to all cases where the distal saphenous trunk is not involved, when the ECD shows a pathological ostial reflux, a truncular reflux limited to the thigh, which may be associated with incontinence of the perforant vein of Dodd.


Assuntos
Veia Safena/cirurgia , Varizes/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Procedimentos Cirúrgicos Vasculares/métodos
9.
J Virol ; 75(20): 9939-46, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11559826

RESUMO

The NS2-NS3 region of the hepatitis C virus polyprotein encodes a proteolytic activity that is required for processing of the NS2/3 junction. Membrane association of NS2 and the autocatalytic nature of the NS2/3 processing event have so far constituted hurdles to the detailed investigation of this reaction. We now report the first biochemical characterization of the self-processing activity of a purified NS2/3 precursor. Using multiple sequence alignments, we were able to define a minimal domain, devoid of membrane-anchoring sequences, which was still capable of performing the processing reaction. This truncated protein was efficiently expressed and processed in Escherichia coli. The processing reaction could be significantly suppressed by growth in minimal medium in the absence of added zinc ions, leading to the accumulation of an unprocessed precursor protein in inclusion bodies. This protein was purified to homogeneity, refolded, and shown to undergo processing at the authentic NS2/NS3 cleavage site with rates comparable to those observed using an in vitro-translated full-length NS2/3 precursor. Size-exclusion chromatography and a dependence of the processing rate on the concentration of truncated NS2/3 suggested a functional multimerization of the precursor protein. However, we were unable to observe trans cleavage activity between cleavage-site mutants and active-site mutants. Furthermore, the cleavage reaction of the wild-type protein was not inhibited by addition of a mutant that was unable to undergo self-processing. Site-directed mutagenesis data and the independence of the processing rate from the nature of the added metal ion argue in favor of NS2/3 being a cysteine protease having Cys993 and His952 as a catalytic dyad. We conclude that a purified protein can efficiently reproduce processing at the NS2/3 site in the absence of additional cofactors.


Assuntos
Hepacivirus/metabolismo , Precursores de Proteínas/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas não Estruturais Virais/metabolismo , Sequência de Aminoácidos , Meios de Cultura , Dimerização , Escherichia coli/genética , Hepacivirus/genética , Corpos de Inclusão/metabolismo , Dados de Sequência Molecular , Precursores de Proteínas/genética , Precursores de Proteínas/isolamento & purificação , Proteínas Recombinantes/biossíntese , Alinhamento de Sequência , Análise de Sequência de Proteína , Proteínas não Estruturais Virais/genética , Zinco
10.
J Nephrol ; 14(1): 27-31, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11281340

RESUMO

BACKGROUND: Severe hyperhomocysteinemia is common in hemodialysis patients, who also present a dramatic increase in plasma concentrations of sulfate, one of the main products of methionine and cysteine catabolism. The aim of this study was to verify the relationship between high plasma sulfate levels and cysteine or homocysteine concentrations in hemodialysis patients. METHODS: Plasma sulfate, cysteine and homocysteine concentrations and some renal efficiency parameters were determined in 18 patients with end-stage renal failure, all undergoing 4h hemodialysis three times a week. The pattern of post-dialysis rises on plasma concentrations of sulfate, cysteine and homocysteine was established. RESULTS: Plasma sulfate, cysteine and homocysteine levels were significantly higher in patients than in normal controls. Plasma sulfate concentrations positively correlated with cysteinemia (p = 0.031; r = 0.482) which, in turn correlated with homocysteinemia (p = 0.042; r = 0.460). Sulfate levels also correlated with blood creatinine (p = 0.004; r = 0.630), nitrogen (p = 0.000; r = 0.899), protein (p = 0.014; r = 0.555), and albumin (p = 0.003; r = 0.642). Post-dialysis rises in sulfate and cysteine were detected some hours before homocysteine. CONCLUSION: The results suggest that high sulfate levels, due mainly to impaired renal function, are involved in the altered metabolism of homocysteine in hemodialysis patients.


Assuntos
Hiper-Homocisteinemia/etiologia , Falência Renal Crônica/terapia , Diálise Renal , Sulfatos/sangue , Cisteína/sangue , Feminino , Homocisteína/sangue , Humanos , Falência Renal Crônica/sangue , Masculino , Pessoa de Meia-Idade
11.
Biochemistry ; 40(3): 631-40, 2001 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-11170379

RESUMO

Maturational cleavage of the hepatitis C virus polyprotein involves the viral chymotrypsin-like serine protease NS3. The substrate binding site of this enzyme is unusually flat and featureless. We here show that NS3 has a highly asymmetric charge distribution that is characterized by strong positive potentials in the vicinity of its active site and in the S5/S6 region. Using electrostatic potential calculations, we identified determinants of this positive potential, and the role of six different residues was explored by site-directed mutagenesis. Mutation of residues in the vicinity of the active site led to changes in k(cat) values of a peptide substrate indicating that basic amino acids play a role in the stabilization of the transition state. Charge neutralization in the S5/S6 region increased the K(m) values of peptide substrates in a manner that depended on the presence of negatively charged residues in the P5 and P6 positions. K(i) values of hexapeptide acids spanning P6-P1 (product inhibitors) were affected by charge neutralization in both the active site region and the S5/S6 region. Pre-steady-state kinetic data showed that the electrostatic surface potential is used by this enzyme to enhance collision rates between peptidic ligands and the active site. Calculations of the interaction energies of protease-substrate or protease-inhibitor complexes showed that electrostatic interaction energies oppose the formation of a tightly bound complex due to an unfavorable change in the desolvation energy. We propose that desolvation costs are minimized by avoiding the formation of individual ion pair interactions through the use of clusters of positively charged residues in the generation of local electrostatic potentials.


Assuntos
Domínio Catalítico , Hepacivirus/enzimologia , Serina Endopeptidases/química , Proteínas não Estruturais Virais/química , Sequência de Aminoácidos , Arginina/genética , Domínio Catalítico/genética , Estabilidade Enzimática/genética , Hepacivirus/genética , Cinética , Lisina/genética , Substâncias Macromoleculares , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Peptídeos/química , Ligação Proteica/genética , Serina/genética , Inibidores de Serina Proteinase/química , Eletricidade Estática , Proteínas não Estruturais Virais/antagonistas & inibidores , Proteínas não Estruturais Virais/genética
12.
Thromb Haemost ; 84(3): 478-83, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11019975

RESUMO

Platelets regulate several polymorphonuclear leukocyte (PMN) functions. We have found that thrombin-stimulated platelets potently inhibited PMN apoptosis. Cell-free supernatant from increasing concentrations of stimulated platelets inhibited PMN apoptosis in a dose-dependent manner, with an effect similar to that of corresponding concentrations of platelets. At the plateau, platelet supernatant inhibited PMN apoptosis by 54.6 +/- 6.8%, the anti-apoptotic activity being higher than that of GM-CSF and comparable to that of LPS. Neither IL-1ra nor a combination of anti-IL1alpha + betamAb affected the activity of platelet supernatant. In contrast a mAb recognizing the active form of TGF-beta1 significantly decreased this activity. Moreover, exogenous TGF-beta1 inhibited PMN apoptosis in a dose-dependent manner. The active form of this cytokine was indeed present in the supernatant of stimulated platelets at a concentration able to elicit an anti-apoptotic effect. The p38 MAPK inhibitor SB203580 prevented the anti-apoptotic effect of TGF-beta1 in a dose-dependent manner. Interestingly, it also prevented the anti-apoptotic effect of IL-1alpha, but not that of GM-CSF, LPS and dexamethasone. In conclusion, we report for the first time that PMN apoptosis is potently inhibited by platelet-released mediators, that TGF-beta1 mediates an important part of this effect, and that p38 MAPK is involved in the TGF-beta1 signaling leading to its anti-apoptotic effect. These results provide novel evidence to support the central role of platelets in inflammation.


Assuntos
Apoptose/efeitos dos fármacos , Neutrófilos/citologia , Fator de Crescimento Transformador beta/fisiologia , Plaquetas/metabolismo , Técnicas de Cultura de Células , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Humanos , Imidazóis/farmacologia , Lipopolissacarídeos/farmacologia , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/fisiologia , Piridinas/farmacologia , Transdução de Sinais , Fator de Crescimento Transformador beta/metabolismo , Fator de Crescimento Transformador beta/farmacologia , Proteínas Quinases p38 Ativadas por Mitógeno
13.
Int J Cancer ; 87(4): 595-600, 2000 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-10918203

RESUMO

Flavonoids are a class of polyphenolic compounds widely distributed in the plant kingdom, which display a variety of biological activities, including chemoprevention and tumor growth inhibition. Our aim was to investigate the effects of several polyphenols on the growth and metastatic potential of B16-BL6 melanoma cells in vivo. Intraperitoneal administration of quercetin, apigenin, (-)-epigallocathechin-3-gallate (EGCG), resveratrol, and the anti-estrogen tamoxifen, at the time of i.m. injection of B16-BL6 cells into syngeneic mice, resulted in a significant, dose-dependent delay of tumor growth, without toxicity. The relative descending order of potency was EGCG > apigenin = quercetin = tamoxifen > resveratrol > control. Furthermore, polyphenols significantly potentiated the inhibitory effect of a non-toxic dose of cisplatin. When tested for the ability to inhibit lung colonization, quercetin, apigenin, and tamoxifen (but not EGCG or resveratrol) significantly decreased the number of B16-BL6 colonies in the lungs in a dose-dependent manner, with quercetin and apigenin being more effective than tamoxifen. Interestingly, quercetin, apigenin, and tamoxifen (but not EGCG or resveratrol) significantly decreased the invasion of B16-BL6 cells in vitro, with quercetin and apigenin being more effective than tamoxifen. This suggests that anti-invasive activity is one of the mechanisms underlying inhibition of lung colonization by quercetin and apigenin. In conclusion, quercetin and apigenin inhibit melanoma growth and invasive and metastatic potential; therefore, they may constitute a valuable tool in the combination therapy of metastatic melanoma.


Assuntos
Anticarcinógenos/farmacologia , Flavonoides/farmacologia , Melanoma Experimental/patologia , Quercetina/farmacologia , Animais , Anticarcinógenos/uso terapêutico , Apigenina , Catequina/análogos & derivados , Catequina/farmacologia , Catequina/uso terapêutico , Divisão Celular/efeitos dos fármacos , Curcumina/farmacologia , Curcumina/uso terapêutico , Feminino , Flavonoides/uso terapêutico , Inibidores do Crescimento/farmacologia , Inibidores do Crescimento/uso terapêutico , Neoplasias Pulmonares/prevenção & controle , Neoplasias Pulmonares/secundário , Melanoma Experimental/prevenção & controle , Melanoma Experimental/secundário , Camundongos , Camundongos Endogâmicos C57BL , Invasividade Neoplásica , Transplante de Neoplasias , Quercetina/uso terapêutico , Resveratrol , Estilbenos/farmacologia , Estilbenos/uso terapêutico , Tamoxifeno/farmacologia , Tamoxifeno/uso terapêutico , Células Tumorais Cultivadas
14.
J Biol Chem ; 275(20): 15106-13, 2000 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-10809747

RESUMO

A serine protease domain contained within the viral NS3 protein is a key player in the maturational processing of the hepatitis C virus polyprotein and a prime target for the development of antiviral drugs. In the present work, we describe a dansylated hexapeptide inhibitor of this enzyme. Active site occupancy by this compound could be monitored following fluorescence resonance energy transfer between the dansyl fluorophore and protein tryptophan residues and could be used to 1) unambiguously assess active site binding of NS3 protease inhibitors, 2) directly determine equilibrium and pre-steady-state parameters of enzyme-inhibitor complex formation, and 3) dissect, using site-directed mutagenesis, the contribution of single residues of NS3 to inhibitor binding in direct binding assays. The assay was also used to characterize the inhibition of the NS3 protease by its cleavage products. We show that enzyme-product inhibitor complex formation depends on the presence of an NS4A cofactor peptide. Equilibrium and pre-steady-state data support an ordered mechanism of ternary (enzyme-inhibitor-cofactor) complex formation, requiring cofactor complexation prior to inhibitor binding.


Assuntos
Hepacivirus/enzimologia , Serina Endopeptidases/química , Serina Endopeptidases/metabolismo , Inibidores de Serina Proteinase/química , Proteínas não Estruturais Virais/química , Proteínas não Estruturais Virais/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Compostos de Dansil , Transferência de Energia , Cinética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oligopeptídeos/química , Oligopeptídeos/metabolismo , Oligopeptídeos/farmacologia , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Inibidores de Serina Proteinase/metabolismo , Inibidores de Serina Proteinase/farmacologia , Espectrometria de Fluorescência , Especificidade por Substrato , Triptofano
15.
Biochemistry ; 39(7): 1849-61, 2000 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-10677236

RESUMO

The replication of the hepatitis C virus (HCV), an important human pathogen, crucially depends on the proteolytic maturation of a large viral polyprotein precursor. The viral nonstructural protein 3 (NS3) harbors a serine protease domain that plays a pivotal role in this process, being responsible for four out of the five cleavage events that occur in the nonstructural region of the HCV polyprotein. We here show that hexapeptide, tetrapeptide, and tripeptide alpha-ketoacids are potent, slow binding inhibitors of this enzyme. Their mechanism of inhibition involves the rapid formation of a noncovalent collision complex in a diffusion-limited, electrostatically driven association reaction followed by a slow isomerization step resulting in a very tight complex. pH dependence experiments point to the protonated catalytic His 57 as an important determinant for formation of the collision complex. K(i) values of the collision complexes vary between 3 nM and 18.5 microM and largely depend on contacts made by the peptide moiety of the inhibitors. Site-directed mutagenesis indicates that Lys 136 selectively participates in stabilization of the tight complex but not of the collision complex. A significant solvent isotope effect on the isomerization rate constant is suggestive of a chemical step being rate limiting for tight complex formation. The potency of these compounds is dominated by their slow dissociation rate constants, leading to complex half-lives of 11-48 h and overall K(i) values between 10 pM and 67 nM. The rate constants describing the formation and the dissociation of the tight complex are relatively independent of the peptide moiety and appear to predominantly reflect the intrinsic chemical reactivity of the ketoacid function.


Assuntos
Hepacivirus/enzimologia , Cetoácidos/química , Oligopeptídeos/química , Serina Endopeptidases/química , Proteínas não Estruturais Virais/antagonistas & inibidores , Alanina/análogos & derivados , Alanina/química , Aminobutiratos/química , Sítios de Ligação , Humanos , Concentração Inibidora 50 , Cetoácidos/metabolismo , Cinética , Ressonância Magnética Nuclear Biomolecular , Oligopeptídeos/síntese química , Oligopeptídeos/metabolismo , Serina Endopeptidases/metabolismo , Espectrometria de Fluorescência , Relação Estrutura-Atividade , Proteínas não Estruturais Virais/metabolismo
16.
Biochemistry ; 37(33): 11459-68, 1998 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-9708981

RESUMO

Hepatitis C virus (HCV) infection is a major health problem that leads to cirrhosis and hepatocellular carcinoma in a substantial number of infected individuals, estimated to be 100-200 million worldwide. Unfortunately, immunotherapy or other effective treatments for HCV infection are not yet available, and interferon administration has limited efficacy. Different approaches to HCV therapy are being explored, and these include inhibition of the viral proteinase, helicase, and RNA-dependent RNA polymerase and development of a vaccine. Here we present the design of selective inhibitors with nanomolar potencies of HCV NS3 proteinase based on eglin c. These eglin c mutants were generated by reshaping the inhibitor active site-binding loop, and the results emphasize the role played by residues P5-P4' in enzyme recognition. In addition, alanine scanning experiments provide evidence that the N terminus of eglin c also contributes to NS3 binding. These eglin inhibitors offer a unique tool for accurately assessing the requirements for effective inhibition of the enzymatic activity of NS3 and at the same time can be considered lead compounds for the identification of other NS3 inhibitors in targeted design efforts.


Assuntos
Hepacivirus/enzimologia , Engenharia de Proteínas , Inibidores de Serina Proteinase/síntese química , Serpinas/síntese química , Proteínas não Estruturais Virais/antagonistas & inibidores , Animais , Humanos , Cinética , Sanguessugas , Substâncias Macromoleculares , Fragmentos de Peptídeos/metabolismo , Ligação Proteica , Engenharia de Proteínas/métodos , Proteínas , RNA Helicases , Serina Endopeptidases , Inibidores de Serina Proteinase/metabolismo , Inibidores de Serina Proteinase/farmacologia , Serpinas/metabolismo , Serpinas/farmacologia , Relação Estrutura-Atividade , Especificidade por Substrato , Termodinâmica
17.
J Virol ; 72(8): 6758-69, 1998 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9658124

RESUMO

The hepatitis C virus (HCV) nonstructural 3 protein (NS3) contains at least two domains associated with multiple enzymatic activities; a serine protease activity resides in the N-terminal one-third of the protein, whereas RNA helicase activity and RNA-stimulated nucleoside triphosphatase activity are associated with the C-terminal portion. To study the possible mutual influence of these enzymatic activities, a full-length NS3 polypeptide of 67 kDa was expressed as a nonfusion protein in Escherichia coli, purified to homogeneity, and shown to retain all three enzymatic activities. The protease activity of the full-length NS3 was strongly dependent on the activation by a synthetic peptide spanning the central hydrophobic core of the NS4A cofactor. Once complexed with the NS4A-derived peptide, the full-length NS3 protein and the isolated N-terminal protease domain cleaved synthetic peptide substrates with comparable efficiency. We show that, as in the case of the isolated protease domain, the protease activity of full-length NS3 undergoes inhibition by the N-terminal cleavage products of substrate peptides corresponding to the NS4A-NS4B and NS5A-NS5B. We have also characterized and quantified the NS3 ATPase, RNA helicase, and RNA-binding activities under optimized reaction conditions. Compared with the isolated N-terminal and C-terminal domains, recombinant full-length NS3 did not show significant differences in the three enzymatic activities analyzed in independent in vitro assays. We have further explored the possible interdependence of the NS3 N-terminal and C-terminal domains by analyzing the effect of polynucleotides on the modulation of all NS3 enzymatic functions. Our results demonstrated that the observed inhibition of the NS3 proteolytic activity by single-stranded RNA is mediated by direct interaction with the protease domain rather than with the helicase RNA-binding domain.


Assuntos
Adenosina Trifosfatases/metabolismo , Hepacivirus/enzimologia , RNA Nucleotidiltransferases/metabolismo , Serina Endopeptidases/metabolismo , Proteínas não Estruturais Virais/metabolismo , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/isolamento & purificação , Sequência de Aminoácidos , Expressão Gênica , Humanos , Cinética , Dados de Sequência Molecular , Biossíntese de Proteínas , RNA/metabolismo , RNA Helicases , RNA Nucleotidiltransferases/genética , RNA Nucleotidiltransferases/isolamento & purificação , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Serina Endopeptidases/genética , Serina Endopeptidases/isolamento & purificação , Especificidade por Substrato , Proteínas não Estruturais Virais/genética , Proteínas não Estruturais Virais/isolamento & purificação
18.
Biochemistry ; 37(25): 8899-905, 1998 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-9636031

RESUMO

The nonstructural protein NS3 of the hepatitis C virus (HCV) harbors a serine protease domain that is responsible for most of the processing events of the nonstructural region of the polyprotein. Its inhibition is presently regarded as a promising strategy for coping with the disease caused by HCV. In this work, we show that the NS3 protease undergoes inhibition by the N-terminal cleavage products of substrate peptides corresponding to the NS4A-NS4B, NS4B-NS5A, and NS5A-NS5B cleavage sites, whereas no inhibition is observed with a cleavage product of the intramolecular NS3-NS4A junction. The Ki values of the hexamer inhibitory products [Ki(NS4A) = 0.6 microM, Ki(NS5A) = 1.4 microM, and Ki(NS4B) = 180 microM] are lower than the Km values of the respective substrate peptides [Km(NS4A-NS4B) = 10 microM, Km(NS5A-NS5B) = 3.8 microM, and Km(NS4B-NS5A) > 1000 microM]. Mutagenesis experiments have identified Lys136 as an important determinant for product binding. The phenomenon of product inhibition can be exploited to optimize peptide inhibitors of NS3 protease activity that may be useful in drug development.


Assuntos
Hepacivirus/enzimologia , Serina Endopeptidases/metabolismo , Inibidores de Serina Proteinase/farmacologia , Proteínas não Estruturais Virais/metabolismo , Sequência de Aminoácidos , Sítios de Ligação/genética , Ligação Competitiva/genética , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oligopeptídeos/farmacologia , Serina Endopeptidases/efeitos dos fármacos , Serina Endopeptidases/genética , Especificidade por Substrato/genética , Proteínas não Estruturais Virais/efeitos dos fármacos , Proteínas não Estruturais Virais/genética
19.
Cancer ; 82(10): 1860-6, 1998 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-9587117

RESUMO

BACKGROUND: The effect of interleukin-6 (IL-6), the major growth factor for myeloma cells, may be enhanced by soluble IL-6 receptor (sIL-6R). Therefore, the current study investigated the clinical significance of serum sIL-6R in patients with multiple myeloma (MM). METHODS: Serum levels of sIL-6R were determined by enzyme-linked immunoassay in 55 normal controls, 81 individuals with monoclonal gammopathy of undetermined significance (MGUS), and 164 patients with MM in various phases of the disease. RESULTS: sIL-6R concentrations were higher in MM patients (162.0 +/- 134.6 ng/mL) than in individuals with MGUS (58.9 +/- 36.7 ng/mL) or in controls (45.6 +/- 22.3 ng/mL) (P = 0.0000). sIL-6R was not found to have a significant linear correlation with any other parameter, including IL-6, beta2-microglobulin (beta2-m), and neopterin, either in newly diagnosed cases or during the course of the disease. In addition, there were no statistically significant differences in sIL-6R concentrations between the clinical stages at the time of diagnosis. In univariate logistic regression analysis sIL-6R was a significant but weak prognostic indicator (P = 0.000000). Kaplan-Meier analysis showed that elevated levels of sIL-6R were associated with shorter survival (P = 0.00282). Patients also were stratified according to their serum beta2-m and sIL-6R levels. Patients with low levels of both parameters had a clear survival benefit over the other groups (P = 0.000000). CONCLUSIONS: The correlation between sIL-6R levels and survival is significant but weak, making it unlikely to be of much value in predicting the outcome of patients with MM alone. The results of the current study support the role of sIL-6R levels in improving the prognostic value of beta2-m and in discriminating patients with MM from individuals with MGUS.


Assuntos
Mieloma Múltiplo/metabolismo , Paraproteinemias/metabolismo , Receptores de Interleucina-6/análise , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Análise de Regressão , Solubilidade
20.
Am J Med Sci ; 315(4): 237-41, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9537637

RESUMO

Eighteen patients with polycythemia vera who were less than 60 years old received human leukocyte interferon-alpha subcutaneously at a starting dose of 3 MU three times a week. The interferon dose was escalated to 6 MU three times a week if it was well tolerated and disease was not controlled after 3 months of treatment at the lower dose. Hematologic response was defined as complete if the hematocrit was maintained at less than 45% in the absence of phlebotomy and partial if the hematocrit was kept at 45% to 50%, associated with a 50% or greater reduction of phlebotomy requirements; no response was defined as a response less than a partial response. Complete disease control was achieved in 11 patients, with partial control in a further six cases. One patient failed to respond. Median duration of response was 16 months (range 5 to 43 months), with 15 patients still under treatment. Therapy with human leukocyte interferon-alpha significantly improved (p <.01) phlebotomy requirements, the degree of splenomegaly, pruritus scores, iron stores and mean red cell volume values, and platelet and leukocyte counts. Interferon treatment did not produce remarkable side effects and no patient withdrew from the study because of intolerance. We conclude that subcutaneous human leukocyte interferon-alpha is an effective and well-tolerated therapy in the management of polycythemia vera-associated myeloproliferation and pruritus in patients less than 60 years old.


Assuntos
Interferon-alfa/uso terapêutico , Policitemia Vera/terapia , Adulto , Feminino , Humanos , Interferon-alfa/efeitos adversos , Masculino , Pessoa de Meia-Idade
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