RESUMO
El vértigo posicional paroxístico benigno (VPPB) es un síndrome vestibular episódico (SVE) que es reconocido por ser el trastorno más frecuente observado en la clínica, siendo de buena y pronta resolución en la gran mayoría de los casos. Sin embargo, pueden presentarse variantes muy poco habituales o atípicas, donde el canalith jam es una de las formas más resistentes al tratamiento mediante maniobras de reposición, y por lo mismo, el reconocimiento adecuado de este cuadro es esencial para su correcto abordaje. Se presentan dos casos de VPPB con canalith jam en el CSC horizontal y se proponen cinco criterios diagnósticos para su identificación.
Benign paroxysmal positional vertigo (BPPV) is an episodic vestibular syndrome (EVS) that is recognized for being the most frequent disorder observed in the clinic, with good and prompt resolution in the vast majority of cases. However, very unusual or atypical variants can occur, where the canalith jam is one of the forms most resistant to treatment by means of repositioning maneuvers, and for the same reason, the adequate recognition of this condition is essential for its correct approach. Two cases of BPPV with canalith jam in the horizontal semicircular canal and five diagnostic criteria for its identification are presented.
Assuntos
Humanos , Masculino , Feminino , Adulto , Doenças Vestibulares/diagnóstico , Doenças Vestibulares/terapia , Canais Semicirculares/patologia , Vertigem Posicional Paroxística Benigna/diagnóstico , Vertigem Posicional Paroxística Benigna/terapiaRESUMO
La terapia de rehabilitación vestibular es el tratamiento con mayor evidencia en la recuperación para la mayoría de los trastornos de equilibrio. En los casos que presentan una alteración estable del procesamiento central del equilibrio, o mixta, es decir, acompañada de una alteración a nivel del sistema nervioso periférico, la terapia de rehabilitación vestibular no se excluye como tratamiento. No obstante, los progresos suelen ser limitados y requieren de una mayor cantidad de sesiones. En este trabajo analizaremos un caso mixto, un paciente con síndrome de núcleo fastigial y el vértigo posicional paroxístico benigno (VPPB), desde la pesquisa y evaluación hasta el tratamiento y alta, en el Hospital Clínico Universidad de Chile.
Vestibular rehabilitation therapy is the treatment with the greatest evidence of recovery for most balance disorders. In the cases that have a loss of central balance processing, or mixed, that is, stable accompanied by a disorder of the peripheral nervous system the vestibular rehabilitation therapy is not excluded as a treatment; however, progress is usually limited and requires a greater number of sessions. In this work we will analyse a mixed case, a patient with nucleus fastigial syndrome and a benign paroxysmal positional vertigo, from the investigation and evaluation to the treatment and discharge, at the Hospital Clínico Universidad de Chile.
Assuntos
Humanos , Masculino , Adulto , Doenças Vestibulares/reabilitação , Reflexo Vestíbulo-Ocular , Vertigem/reabilitação , Tontura/reabilitação , Equilíbrio PosturalRESUMO
BACKGROUND: Lawsonia intracellularis remains a problem for the swine industry worldwide. Previously, we designed and obtained a vaccine candidate against this pathogen based on the chimeric proteins: OMP1c, OMP2c, and INVASc. These proteins formed inclusion bodies when expressed in E. coli, which induced humoral and cellular immune responses in vaccinated pigs. Also, protection was demonstrated after the challenge. In this study, we established a production process to increase the yields of the three antigens as a vaccine candidate. RESULTS: Batch and fed-batch fermentations were evaluated in different culture conditions using a 2 L bioreactor. A fed-batch culture with a modified Terrific broth medium containing glucose instead of glycerol, and induced with 0.75 mM IPTG at 8 h of culture (11 g/L of biomass) raised the volumetric yield to 627.1 mg/L. Under these culture conditions, plasmid-bearing cells increased by 10% at the induction time. High efficiency in cell disruption was obtained at passage six using a high-pressure homogenizer and a bead mill. The total antigen recovery was 64% (400 mg/L), with a purity degree of 70%. The antigens retained their immunogenicity in pigs, inducing high antibody titers. CONCLUSIONS: Considering that the antigen production process allowed an increment of more than 70-fold, this methodology constitutes a crucial step in the production of this vaccine candidate against L. intracellularis.
Assuntos
Animais , Doenças dos Suínos/imunologia , Vacinas Bacterianas/imunologia , Lawsonia (Bactéria)/imunologia , Infecções por Desulfovibrionaceae/prevenção & controle , Suínos , Doenças dos Suínos/prevenção & controle , Vacinas Bacterianas/administração & dosagem , Vacinas Sintéticas , Sobrevivência Celular , Vacinação , Fermentação , Técnicas de Cultura Celular por Lotes , ImunidadeRESUMO
Background and study aims ESG is an effective and safe medium-term procedure for obesity treatment. A variety of suture patterns have been reported. We aimed to compare whether there are differences in efficacy depending on suture pattern used. Patients and methods Retrospective and comparative review of 5 years of prospectively collected data, including consecutive obese patients undergoing ESG at two collaborative centers. Primary outcomes included weight loss (mainly % total body weight loss [TBWL] and % exces weight loss [EWL]) at 12 months and safety profile. We compared them according to three suture patterns (transverse bilinear [TBp], longitudinal [Lp] and transverse monolinear [TMp]), and number of sutures (4â-â7) and stitches (<â25, 25 to 30 and >â30) applied. Evolution of major obesity-associated morbidities (hypertension, dyslipidemia, Type 2 diabetes mellitus (T2DM), sleep obstructive apnea syndrome, and arthropathy) were also described. Results 88 patients (mean age 46.1±12.3 years, 69.3â% female) underwent ESG. Mean body mass index (BMI) at baseline was 39.40â±â4.69âkg/m². At 1 year, %TBWL was 17.36â±â6.09â% (%EWL 46.41±20.6â%) with TBWL >â10â% in 95.5â% of patients (EWLâ>â25â% in 94.3â% of patients). According to pattern, there were no differences in %TBWL but there were in %EWL (43.7â±â20.4â%, 59.8â±â18.9â% and 45.4â±â14.9â% in TBp, Lp and TMp patterns, respectively) ( P â=â0.034). No differences were found related to number of sutures (mean 5.2â±â0.73, râ=â4â-â7) or stitches (mean 27.4â±â6.50, râ=â18â-â50) applied. Forty-three of 72 (59.7â%) major comorbidities were resolved. No serious adverse events were observed with any pattern. Conclusions ESG is an effective procedure at 12-month follow-up for weight loss and comorbidity resolution. All three analyzed patterns are safe and effective without differences in %TBWL, but there was a slight increase in %EWL in Lp, regardless of the number of sutures or stitches applied.
RESUMO
Mesenchymal stem cell (MSC)-based therapy is being increasingly considered a powerful opportunity for several disorders based on MSC immunoregulatory properties. Nonetheless, MSC are versatile and plastic cells that require an efficient control of their features and functions for their optimal use in clinic. Recently, we have shown that PPARß/δ is pivotal for MSC immunoregulatory and therapeutic functions. However, the role of PPARß/δ on MSC metabolic activity and the relevance of PPARß/δ metabolic control on MSC immunosuppressive properties have never been addressed. Here, we demonstrate that PPARß/δ deficiency forces MSC metabolic adaptation increasing their glycolytic activity required for their immunoregulatory functions on Th1 and Th17 cells. Additionally, we show that the inhibition of the mitochondrial production of ATP in MSC expressing PPARß/δ, promotes their metabolic switch towards aerobic glycolysis to stably enhance their immunosuppressive capacities significantly. Altogether, these data demonstrate that PPARß/δ governs the immunoregulatory potential of MSC by dictating their metabolic reprogramming and pave the way for enhancing MSC immunoregulatory properties and counteracting their versatility.
Assuntos
Células-Tronco Mesenquimais/metabolismo , PPAR beta/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Animais , Células da Medula Óssea/citologia , Linfócitos T CD4-Positivos/citologia , Proliferação de Células , Inativação Gênica , Glicólise , Terapia de Imunossupressão , Camundongos , Oligomicinas/química , Células Th1/citologia , Células Th17/citologiaRESUMO
Few vaccine adjuvants have been approved for human use although several are currently being studied in preclinical and clinical trial. MPL is a toll-like receptor agonist able to trigger a high and persistent antibody response via-TLR-4 while QS-21 activates the NLRP3 inflammasome. Data suggest that there is a cross-talk between Notch and TLR signaling pathways modulating the polarization of the immune response in a MyD88-dependent manner. However, the role of Notch on the mechanism action of immunogenic adjuvants has not been addressed yet. This study aims to evaluate the in vitro toxicity and inflammatory response triggered by MPL and QS-21 using an in vitro human cell co-culture model and to determine whether NFκB or Notch signaling pathways are involved in their mechanism of immunotoxicity. In order to do this, we evaluated the effect of QS- 21/MPL alone or in combination using a co-culture of PBMC and HUVEC using cytotoxicity, surface expression of ECAMs, cell adhesion and cytokine release, NF-κB activation and NOTCH1 expression as observation endpoints. We found that both MPL and QS-21 were cytotoxic at concentrations over 5 µg/mL. Both adjuvants were able to trigger the expression of ECAMs and induce firm adhesion of PBMC to the endothelium. QS-21 and MPL combination demonstrated a synergistic effect on cellular recruitment and cytokine release generating a switch from Th2 to Th1 cytokine profile. Both MPL and QS-21 by themselves were able to generate significant NF-κB activation. However, this effect was not observed when both adjuvants were combined. On the contrary, the adjuvants alone and combined induced an overexpression of NOTCH-1. This is an important finding, as it provides new evidence that these adjuvants could modulate reactogenicity of vaccines through Notch signaling.
Assuntos
Adjuvantes Imunológicos/toxicidade , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Leucócitos Mononucleares/efeitos dos fármacos , Lipídeo A/análogos & derivados , Receptor Notch1/genética , Saponinas/toxicidade , Adesão Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Técnicas de Cocultura , Citocinas/metabolismo , Interações Medicamentosas , Células Endoteliais da Veia Umbilical Humana/fisiologia , Humanos , Leucócitos Mononucleares/fisiologia , Lipídeo A/toxicidade , NF-kappa B/metabolismoRESUMO
Granulomas are the interface between host and mycobacteria, and are crucial for the surivival of both species. While macrophages are the main cellular component of these lesions, different lymphocyte subpopulations within the lesions also play important roles. Lymphocytes are continuously recruited into these inflammatory lesions via local vessels to replace cells that are either dying or leaving; however, their rate of replacement is not known. Using a model of granuloma transplantation and fluorescently labeled cellular compartments we report that, depending on the subpopulation, 10-80%, of cells in the granuloma are replaced within one week after transplantation. CD4(+) T cells specific for Mycobacterium antigen entered transplanted granulomas at a higher frequency than Foxp3(+) CD4(+) T cells by one week. Interestingly, a small number of T lymphocytes migrated out of the granuloma to secondary lymphoid organs. The mechanisms that define the differences in recruitment and efflux behind each subpopulation requires further studies. Ultimately, a better understanding of lymphoid traffic may provide new ways to modulate, regulate, and treat granulomatous diseases.
RESUMO
Los pacientes desdentados totales pierden con el pasar del tiempo la altura de proceso alveolar residual, lo que complica de manera importante una rehabilitación protésica adecuada , una de las formas de obtener la altura necesaria es la vestíbuloplastía de epitelización secundaria con incisión labial / técnica Kazanjian, así como también el uso de dos implantes mandibulares para una sobredentadura.
Assuntos
Humanos , Feminino , Idoso , Prótese Dentária Fixada por Implante , Revestimento de Dentadura , Procedimentos Cirúrgicos Bucais/métodos , Vestibuloplastia/métodos , Perda do Osso Alveolar/cirurgia , Reabilitação Bucal/métodos , Retalhos CirúrgicosRESUMO
A strategy for fed-batch cultivation of t-PA producing recombinant CHO cells is presented, based on the substitution of glucose and glutamine for slowly metabolized nutrients and in a rational design of the medium. Media for the batch and fed stages were based on the cell specific amino acid requirements, which allowed a more accurate determination of the initiation of the fed stage and the frequency of nutrient addition from then on. Salt concentration was also reduced in both media to avoid an increase in osmolality. As a consequence of this rational design, most amino acid did not accumulate significantly during the fed stage, as usually occurs when their supply is not based on cell requirements; also, lower amounts of by-products were obtained when osmolality level was kept low, that altogether increased viability, longevity and t-PA production when compared with a reference batch culture. Alternating glucose and galactose during the fed stage, allowed lactate detoxification of the cells through their own metabolism. This allowed an increase in cell growth and cell viability with respect to a fed-batch culture in which only glucose was used in the fed stage.
Assuntos
Meios de Cultura , Glucose/metabolismo , Glutamina/metabolismo , Ativador de Plasminogênio Tecidual/biossíntese , Animais , Células CHO , Sobrevivência Celular , Cricetinae , Cricetulus , Galactose/análise , Galactose/metabolismo , Glucose/análise , Ácido Glutâmico/análise , Ácido Glutâmico/metabolismo , Ácido Láctico/análise , Ácido Láctico/metabolismo , Fatores de TempoRESUMO
BACKGROUND: Ultrasonography is useful in trauma patients to detect pleural effusions or peritoneal fluid. AIM: To assess the value of ultrasonography performed by surgeons in the assessment of trauma patients. MATERIAL AND METHODS: A retrospective review of ultrasonography reports and clinical history of 284 trauma patients. RESULTS: One hundred fifty six patients had blunt trauma and 128 had penetrating trauma. Ultrasonography detected peritoneal fluid in 20 per cent, pericardial effusion in 1 per cent and pleural effusion in 1 per cent. Eight percent had visceral damage or hematomas, without peritoneal fluid. None of the patients with a normal ultrasonography required surgery for hemoperitoneum; however, four patients had intestinal perforations and required surgery. CONCLUSIONS: Ultrasonography had a 100 per cent sensitivity and specificity for the detection of clinically significant hemoperitoneum. Emergency ultrasonography performed by surgeons is useful and accurate.
Assuntos
Humanos , Masculino , Feminino , Adulto , Ferimentos e Lesões , Tratamento de Emergência , Centros de Traumatologia , Estudos Retrospectivos , Ferimentos Penetrantes/cirurgia , Ferimentos Penetrantes , Ferimentos e Lesões/cirurgia , Fraturas Fechadas/cirurgia , Fraturas Fechadas , Hemoperitônio , Sensibilidade e EspecificidadeRESUMO
The effect of glutamine replacement by glutamate and the balance between glutamate and glucose metabolism on the redistribution of t-PA-producing recombinant CHO cells metabolism is studied in a series of glucose shift down and shift up experiments in continuous culture. These experiments reveal the existence of multiple steady states, and experimental data are used to perform metabolic flux analysis to gain a better insight into cellular metabolism and its redistribution. Regulation of glucose feed rate promotes a higher efficiency of glucose and nitrogen source utilization, with lower production of metabolic byproducts, but this reduces t-PA specific production rate. This reduction under glucose limitation can be attributed to the fact that the cells are forced to efficiently utilize the carbon and energy source for growth, impairing the production of dispensable metabolites. It is, therefore, the combination of growth rate and carbon and energy source availability that determines the level of t-PA production in continuous culture.
Assuntos
Ácido Glutâmico/metabolismo , Trifosfato de Adenosina/metabolismo , Algoritmos , Animais , Células CHO , Contagem de Células , Técnicas de Cultura de Células/métodos , Cricetinae , Meios de Cultura , Glucose/metabolismo , Ácidos Cetoglutáricos/metabolismo , Ácido Pirúvico/metabolismo , Proteínas Recombinantes/biossínteseRESUMO
The development of a strategy for the culture of Chinese hamster ovary (CHO) cells producing tissue plasminogen activator (t-PA) is investigated. This strategy is based on the replacement of the main carbon source, glucose, by another compound that is slowly metabolizable, particularly galactose. The introduction of this change allows for acute change in cell behavior at various levels. Cell growth is stopped after this nutrient shift, and the cells can be kept in long-duration culture at a low growth rate and high viability as compared with a culture strategy based solely on glucose utilization. Moreover, the capability of cells to produce recombinant proteins (t-PA in this work) can be maintained over the entire period of galactose feeding. From the metabolic point of view, use of a slowly metabolizable carbon source (galactose) introduces important changes in the production of lactate, ammonia, and some amino acids. The use of this metabolic shift enables the generation of biphasic processes, with a first phase with cell growth on glucose and a second stationary phase on galactose, which is particularly suited to perfusion systems.
Assuntos
Técnicas de Cultura de Células/métodos , Galactose/química , Glucose/química , Aminoácidos/química , Amônia/química , Animais , Células CHO , Carbono/química , Divisão Celular , Células Cultivadas , Cricetinae , Glucose/metabolismo , Ácido Láctico/química , Fatores de TempoRESUMO
Introducción: en el ámbito mundial la otitis media aguda (OMA) es la segunda causa de enfermedad en la infancia y el motivo más común de visita al pediatra. Los gérmenes causales de OMA son resistentes a los antibióticos comúnmente utilizados para combatir esta enfermedad, por lo que surge la necesidad de buscar nuevas alternativas de tratamiento. Material y métodos: del 1§ de agosto al 31 de octubre de 1999, en el CMN "20 de Noviembre" del ISSSTE, México, D.F., se realizó un estudio prospectivo a un grupo de 30 niños, con edades entre 3 meses y 6 años, con peso menor a 25 kg. En la primera visita se les practicó examen clínico, otoscopía, cultivo de secreción ótica, además de administrárseles amoxicilina/sulbactam (Trifamox IBL 500) a 50 mg/kg/día durante 10 días. Posteriormente se les realizó nueva valoración clínica los días 1, 3, 10 y 40 que siguieron al inicio del tratamiento, para valorar cumplimiento, efectos adversos y eficacia del antibiótico. Resultados: de los 30 niños estudiados, 12 fueron de sexo femenino y 18 del masculino, con una edad promedio de 19.3 meses, peso promedio de 12.2 kg y un error estándar de 0.5. Todos cumplieron con el tratamiento; los microorganismos aislados fueron Streptococcus pneumoniae 36.7 por ciento (11/30), Haemophilus influenzae 33.3 por ciento (10/30), Staphylococcus aureus 3.3 por ciento (1/30), Staphylococcus epidermidis 3.3 por ciento (1/30), Klebsiella Oxytoca 3.3 por ciento (1/30), y ninguno en 20.1 por ciento (6/30). Los efectos secundarios fueron diarrea en 16.7 por ciento (5/30), náuseas 10 por ciento (3/30), sarpullido 6.7 por ciento (2/30). Todos los niños presentaron cura clínica. Conclusiones: la administración de amoxicilina/sulbactam es eficaz y segura como antibiótico en niños con OMA.
Assuntos
Humanos , Masculino , Feminino , Lactente , Pré-Escolar , Amoxicilina/uso terapêutico , Otite Média/tratamento farmacológico , Sulbactam/uso terapêutico , Resultado do Tratamento , Quimioterapia Combinada/uso terapêuticoRESUMO
The formulation of the culture medium for a Chinese hamster ovary (CHO) cell line has been investigated in terms of the simultaneous replacement of glucose and glutamine, the most commonly employed carbon and nitrogen sources, pursuing the objective of achieving a more efficient use of these compounds, simultaneously avoiding the accumulation of lactate and ammonium in the medium. The key factor in this process is the selection of compounds that are slowly metabolized. Among the different compounds studied, galactose and glutamate provide the best results, allowing support of cell growth with an optimal balance between nutrient uptake and cell requirements and the generation of minimal quantities of lactate and ammonium. The attained results also highlight the capacity of the cells to redistribute their metabolism as a response to the changes in medium composition.
Assuntos
Células CHO , Meios de Cultura/análise , Animais , Biotecnologia , Células CHO/citologia , Células CHO/metabolismo , Divisão Celular , Cricetinae , Meios de Cultura/metabolismo , Estudos de Avaliação como Assunto , Glucose/análise , Glucose/metabolismo , Glutamina/análise , Glutamina/metabolismo , Cinética , Ácido Láctico/metabolismo , Compostos de Amônio Quaternário/metabolismoRESUMO
A recent study has linked the butyrylcholinesterase (BChE) K-variant and the apolipoprotein epsilon4 isoform to late-onset Alzheimer's disease. These findings have been controversial and have led us to examine the differences between wild-type and K-variant BChE in enzyme activity, protein stability, and quaternary structure. J-variant BChE (E497V/A539T) was also studied because it is associated with the K-variant mutation. The K-variant mutation (A539T) is located in the C-terminal tetramerization domain. Wild-type, K-variant, and J-variant BChE were expressed in Chinese hamster ovary cells and purified. The purified enzymes had similar binding affinity (Km) values and catalytic rates for butyrylthiocholine and benzoylcholine. In pulse-chase studies the K-variant, J-variant, and wildtype BChE were degraded rapidly within the cell, with a half-time of approximately 1.5 h. Less than 5% of the intracellular BChE was exported. The C-terminal peptide containing the K-variant mutation interacted with itself as strongly as did the wild-type peptide in the yeast two-hybrid system. Both K-variant and wild-type BChE assembled into tetramers in the presence of poly-L-proline or the proline-rich attachment domain of the collagen tail. The native K-variant BChE in serum showed the same proportion of tetramers as the native serum wild-type BChE. We conclude that the K-variant BChE is similar to wild-type BChE in enzyme activity, protein turnover, and tetramer formation.
Assuntos
Butirilcolinesterase/genética , Butirilcolinesterase/metabolismo , Variação Genética/fisiologia , Estrutura Quaternária de Proteína , Adulto , Animais , Butirilcolinesterase/sangue , Butirilcolinesterase/química , Células CHO/metabolismo , Catálise , Cricetinae , Feminino , Frequência do Gene , Humanos , Masculino , Mutação/fisiologiaRESUMO
Human butyrylcholinesterase (BChE) in serum is composed predominantly of tetramers. The tetramerization domain of each subunit is contained within 40 C-terminal residues. To identify key residues within this domain participating in tetramer stabilization, the interaction between C-terminal 46 residue peptides was quantitated in the yeast two-hybrid system. The wild-type peptide interacted strongly with another wild-type peptide in the yeast two-hybrid system. The C571A mutant peptides interacted to a similar degree as the wild-type. However, the mutant in which seven conserved aromatic residues (Trp 543, Phe 547, Trp 550, Tyr 553, Trp 557, Phe 561, and Tyr 564) and C571 were altered to alanines showed only 12% of the interaction seen with the wild-type peptide. The seven mutations (aromatics-off) were incorporated into the complete BChE molecule, with or without the C571A mutation, and expressed in 293T and CHO-K1 cells. Expression of wild-type BChE in these cell lines yielded 10% tetramers. The aromatics-off mutant formed dimers and monomers but no tetramers. The aromatics-off/C571A mutant yielded only monomers. Addition of poly-L-proline to culture medium, or coexpression with the N-terminus of COLQ including the proline-rich attachment domain (Q(N)PRAD), increased the amount of tetrameric wild-type BChE from 10 to 70%, but had no effect on the G534stop (lacking 41 C-terminal residues) and the aromatics-off mutants. Recombinant BChE produced by coexpression with Q(N)PRAD was purified by column chromatography. The purified tetramers contained the FLAG-tagged Q(N)PRAD peptide. These observations suggest that the stabilization of BChE tetramers is mediated through the interaction of the seven conserved aromatic residues and that poly-L-proline and PRAD act through these aromatic residues to induce tetramerization.
Assuntos
Butirilcolinesterase/química , Sequência Conservada , Fragmentos de Peptídeos/química , Sequência de Aminoácidos , Animais , Butirilcolinesterase/genética , Butirilcolinesterase/metabolismo , Células CHO , Linhagem Celular , Cricetinae , Cisteína/genética , Dimerização , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Peptídeos/química , Peptídeos/metabolismo , Plasmídeos/genética , Conformação Proteica , Estrutura Terciária de Proteína , Saccharomyces cerevisiae/genéticaRESUMO
Human butyrylcholinesterase (BChE) is composed predominantly of tetramers. Our laboratory has shown that up to 40 carboxy terminal residues of each subunit contribute to the stabilization of tetramers (R.M. Blong, E. Bedows, O. Lockridge, The tetramerization domain of butyrylcholinesterase is at the carboxy-terminus, Biochem. J. 327 (1997) 747-757). To better define the residues which participate in tetramer stabilization, the in vivo interaction of the BChE C-terminus 46 residue peptide was quantitated for wild type and mutant BChE using the yeast two-hybrid system. The wild type C-terminal peptides interacted with one another in this system. The K-variant (A539T) and C571A peptides showed interaction similar to that of the wild type. However, only 11.7% of the interaction seen with the wild type peptide was observed with the mutant in which seven conserved aromatic residues (Trp 543, Phe 547, Trp 550, Tyr 553, Trp 557, Phe 561, and Tyr 564) had been altered to alanines (aromatics off mutant). When these seven mutations were incorporated into the complete BChE molecule and expressed in 293T cells, only monomers and dimers were observed. The addition of poly-L-proline to the medium of 293T cells expressing wild type BChE resulted in the increase of the tetrameric form, similar to that observed by Bon et al. (S. Bon, F. Coussen, J. Massoulié, Quaternary associations of acetylcholinesterase II. The polyproline attachment domain of the collagen tail, J. Biol. Chem. 272 (1997) 3016-3021) for acetylcholinesterase expressed in COS cells. However, no increase in tetramers was observed with poly-L-proline addition to the medium of 293T cells expressing the aromatics off BChE mutant. These observations suggest that the stabilization of BChE tetramers is mediated through the interaction of the seven conserved aromatic residues, Trp 543, Phe 547, Trp 550, Tyr 553, Trp 557, Phe 561, and Tyr 564, and that the poly-L-proline induced increase in tetrameric BChE is mediated through these seven aromatic residues.
Assuntos
Butirilcolinesterase/química , Sequência Conservada , Fragmentos de Peptídeos/farmacologia , Sequência de Aminoácidos , Animais , Butirilcolinesterase/genética , Butirilcolinesterase/farmacologia , Gatos , Bovinos , Galinhas , Humanos , Camundongos , Dados de Sequência Molecular , Mutação , Fragmentos de Peptídeos/biossíntese , Fragmentos de Peptídeos/genética , Conformação Proteica , Coelhos , Ratos , Homologia de Sequência de Aminoácidos , TorpedoRESUMO
Butyrylcholinesterase (BChE) has a major role in cocaine detoxication. The rate at which human BChE hydrolyzes cocaine is slow, with a kcat of 3.9 min(-1) and Km of 14 microM. Our goal was to improve cocaine hydrolase activity by mutating residues near the active site. The mutant A328Y had a kcat of 10.2 min(-1) and Km of 9 microM for a 4-fold improvement in catalytic efficiency (kcat/Km). Since benzoylcholine (kcat 15,000 min(-1)) and cocaine form the same acyl-enzyme intermediate but are hydrolyzed at 4000-fold different rates, it was concluded that a step leading to formation of the acyl-enzyme intermediate was rate-limiting. BChE purified from plasma of cat, horse, and chicken was tested for cocaine hydrolase activity. Compared with human BChE, horse BChE had a 2-fold higher kcat but a lower binding affinity, cat BChE was similar to human, and chicken BChE had only 10% of the catalytic efficiency. Naturally occurring genetic variants of human BChE were tested for cocaine hydrolase activity. The J and K variants (E497V and A539T) had k(cat) and Km values similar to wild-type, but because these variants are reduced to 66 and 33% of normal levels in human blood, respectively, people with these variants may be at risk for cocaine toxicity. The atypical variant (D70G) had a 10-fold lower binding affinity for cocaine, suggesting that persons with the atypical variant of BChE may experience severe or fatal cocaine intoxication when administered a dose of cocaine that is not harmful to others.
Assuntos
Butirilcolinesterase/metabolismo , Cocaína/metabolismo , Animais , Sítios de Ligação , Butirilcolinesterase/química , Butirilcolinesterase/genética , Catálise , Galinhas , Cocaína/intoxicação , Overdose de Drogas/tratamento farmacológico , Variação Genética , Cavalos , Humanos , Hidrólise , MutaçãoRESUMO
Inactivation of immobilized penicillin acylase has been studied in the presence of substrate (penicillin G) and products (phenylacetic acid and 6-aminopenicillanic acid), under the hypothesis that substances which interact with the enzyme molecule during catalysis will have an effect on enzyme stability. The kinetics of immobilized penicillin acylase inactivation was a multistage process, decay constants being evaluated for the free-enzyme and enzyme complexes, from whose values modulation factors were determined for the effectors in each enzyme complex at each stage. 6-Aminopenicillanic acid and penicillin G stabilized the enzyme in the first stage of decay. Modulation factors in that stage were 0.96 for penicillin G and 0.98 for 6-aminopenicillanic acid. Phenylacetic acid increased the rate of inactivation in both stages, modulating factors being -2.31 and -2.23, respectively. Modulation factors influence enzyme performance in a reactor and are useful parameters for a proper evaluation.