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1.
HNO ; 64(6): 376-85, 2016 Jun.
Artículo en Alemán | MEDLINE | ID: mdl-27226203

RESUMEN

BACKGROUND: Lacrimal probing and syringing for connatal dacryostenosis can be performed under local (LA) and general anesthesia (GA). In cases of invasive medical procedures, pain and anxiety can be distressing for children and their parents. MATERIALS AND METHODS: Using questionnaires (n = 65), parents were asked to evaluate their own stress and that of their child during lacrimal probing and syringing. Analyzing different subgroups, the impact of the kind of anesthesia (LA vs. GA), trust in medical treatment, therapeutic success, prior experiences with GA, parental educational level, age of parents and children, number of children, and time between the intervention and the interview on the stress was examined. Stress level was evaluated on a scale from 1 (no stress) to 10 (maximal stress). RESULTS: Mean children's age was 8.5 ± 7.42 months. Mean age of the parents was 30.8 ± 6.17 years. Treating children under LA, parents reported moderate to severe stress levels for themselves (mean, M = 7.15) and for their children (M = 7.82). Children's stress levels were significantly higher when the treatment was performed under LA (n = 47; M = 7.34) in comparison to GA (n = 18; M = 6.06; p < 0.05). Parents having two or more children reported significantly lower stress levels than those with only one child. Furthermore, prior experiences with GA led to significantly higher parental stress levels when their children were treated under GA. Other factors did not show any impact on parent's and children's stress levels. CONCLUSIONS: Parents might have been influenced by hearing the children's reaction (e. g., crying) during the intervention under LA. Nevertheless, parents had a higher acceptance of this type of intervention (LA) in comparison to GA. This effect was even stronger among parents with prior experience of GA.


Asunto(s)
Ansiedad/psicología , Dolor Ocular/psicología , Obstrucción del Conducto Lagrimal/psicología , Padres/psicología , Succión/efectos adversos , Succión/psicología , Adulto , Ansiedad/etiología , Niño , Dolor Ocular/etiología , Femenino , Humanos , Obstrucción del Conducto Lagrimal/complicaciones , Obstrucción del Conducto Lagrimal/terapia , Masculino , Succión/métodos , Resultado del Tratamiento
2.
Ultraschall Med ; 36(2): 122-31, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25876060

RESUMEN

PURPOSE: To analyse the incidence of bleeding after percutaneous ultrasound guided diagnostic and therapeutic intraabdominal interventions in a prospective multicentre study (DEGUM percutaneous interventional ultrasound study). MATERIALS AND METHODS: Within a time period of 2 years diagnostic and therapeutic intraabdominal interventions (with the exclusion of ascites paracentesis) performed percutaneously under continuous ultrasound (US) guidance were prospectively assessed using a pseudonymized standardized web site entry form. Number and type of intervention, operator experience, patient characteristics, medication, lab data as well as technical aspects of the procedure and bleeding complications were analysed according to the interventional radiology standards. RESULTS: 8172 US-guided intraabdominal interventions (liver n = 5903; pancreas n = 501, kidney n = 434, lymph node = 272, biliary system n = 153, spleen n = 63, other abdominal organs and extra-organic targets n = 999) were analysed in 30 hospitals. The majority were diagnostic biopsies including 1780 liver parenchyma, 3400 focal liver lesions and 404 pancreatic lesions. 7525 interventions (92.1 %) were performed in hospitalized patients (mean age 62.6 years). Most operators were highly experienced in US-guided interventions (> 500 interventions prior to the study n = 5729; 70.1 %). Sedation was administered in 1131 patients (13.8 %). Needle diameter was ≥ 1 mm in 7162 punctures (87.9 %) with main focus on core needle biopsies (18 G, n = 4185). Clinically relevant bleeding complications with need of transfusion (0.4 %), surgical bleeding control (0.1 %) and radiological coiling (0.05 %) were very rare. Bleeding complications with fatal outcome occurred in four patients (0.05 %). The frequency of major bleeding complications was significantly higher in patients with an INR > 1.5 (p < 0.001) and patients taking a medication potentially interfering with platelet function or plasmatic coagulation (p < 0.0333). CONCLUSION: This prospective multicentre study confirms the broad spectrum of percutaneous US-guided intraabdominal interventions. However diagnostic liver biopsies dominate with the use of core needle biopsies (18 G). Percutaneous US-guided interventions performed by experienced sonographers are associated with a low bleeding risk. Major bleeding complications are very rare. A pre-interventional INR < 1.5 and individual medication risk assessment are recommended.


Asunto(s)
Abdomen/diagnóstico por imagen , Biopsia con Aguja Gruesa/efectos adversos , Hemoperitoneo/epidemiología , Ultrasonografía Intervencional/efectos adversos , Vísceras/patología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Competencia Clínica , Estudios Transversales , Femenino , Hemoperitoneo/etiología , Humanos , Relación Normalizada Internacional , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Riesgo , Ultrasonografía Intervencional/estadística & datos numéricos , Adulto Joven
3.
Artículo en Alemán | MEDLINE | ID: mdl-38916602

RESUMEN

We report an immunocompromised patient with a complex cutaneous leishmaniasis (CL) who suffered from singular bone involvement of the little left toe due to Leishmania (L.) infantum infection. The diagnosis was confirmed by positive polymerase chain reaction (PCR) testing in skin and bone tissue. The patient was successfully treated with miltefosine. In immunocompromised patients with CL, extracutaneous manifestations should always be ruled out. This is the first case report describing osseous involvement in CL due to Leishmania infantum.

5.
Science ; 275(5296): 67-70, 1997 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-8974393

RESUMEN

The controversial question of how thiamine diphosphate, the biologically active form of vitamin B1, is activated in different enzymes has been addressed. Activation of the coenzyme was studied by measuring thermodynamics and kinetics of deprotonation at the carbon in the 2-position (C2) of thiamine diphosphate in the enzymes pyruvate decarboxylase and transketolase by use of nuclear magnetic resonance spectroscopy, proton/deuterium exchange, coenzyme analogs, and site-specific mutant enzymes. Interaction of a glutamate with the nitrogen in the 1'-position in the pyrimidine ring activated the 4'-amino group to act as an efficient proton acceptor for the C2 proton. The protein component accelerated the deprotonation of the C2 atom by several orders of magnitude, beyond the rate of the overall enzyme reaction. Therefore, the earlier proposed concerted mechanism or stabilization of a C2 carbanion can be excluded.


Asunto(s)
Piruvato Descarboxilasa/metabolismo , Tiamina Pirofosfato/metabolismo , Transcetolasa/metabolismo , Regulación Alostérica , Sitios de Unión , Catálisis , Deuterio/metabolismo , Activación Enzimática , Ácido Glutámico/metabolismo , Concentración de Iones de Hidrógeno , Cinética , Espectroscopía de Resonancia Magnética , Mutagénesis Sitio-Dirigida , Protones , Piruvato Descarboxilasa/química , Piruvatos/metabolismo , Termodinámica , Tiamina Pirofosfato/química , Transcetolasa/química
6.
Biochemistry (Mosc) ; 74(3): 293-300, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19364324

RESUMEN

In this work, we investigated the rate of formation of the central intermediate of the transketolase reaction with thiamine diphosphate (ThDP) or 4'-methylamino-ThDP as cofactors and its stability using stopped-flow spectroscopy and circular dichroism (CD) spectroscopy. The intermediates of the transketolase reaction were analyzed by NMR spectroscopy. The kinetic stability of the intermediate was shown to be dependent on the state of the amino group of the coenzyme. The rates of the intermediate formation were the same in the case of the native and methylated ThDP, but the rates of the protonation or oxidation of the complex in the ferricyanide reaction were significantly higher in the complex with methylated ThDP. A new negative band was detected in the CD spectrum of the complex transketolase--4'-methylamino-ThDP corresponding to the protonated dihydroxyethyl-4'-methylamino-ThDP released from the active sites of the enzyme. These data suggest that transketolase in the complex with the NH2-methylated ThDP exhibits dihydroxyethyl-4'-methylamino-ThDP-synthase activity. Thus, the 4'-amino group of the coenzyme provides kinetic stability of the central intermediate of the transketolase reaction, dihydroxyethyl-ThDP.


Asunto(s)
Tiamina Pirofosfato/química , Tiamina/química , Transcetolasa/química , Sitios de Unión , Catálisis , Dominio Catalítico , Dicroismo Circular , Coenzimas/química , Coenzimas/metabolismo , Cinética , Modelos Químicos , Modelos Moleculares , Estructura Molecular , Estructura Terciaria de Proteína , Especificidad por Sustrato , Tiamina/metabolismo , Tiamina Pirofosfato/metabolismo , Transcetolasa/metabolismo
7.
Eur J Surg Oncol ; 42(1): 71-7, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26382101

RESUMEN

PURPOSE: Oncoplastic surgery is a well-established discipline that combines conserving treatment for breast cancer with immediate plastic reconstruction. Although widely practiced, the oncologic outcomes of this combined approach are reported only in small series. The aim of the present paper is to assess the safety of oncoplastic surgery for invasive primary breast cancer. METHODS: We compared 454 consecutive patients who underwent an oncoplastic approach between 2000 and 2008 for primary invasive breast tumors (study group) with twice the number of patients who received conservation alone in the same interval time (control group). Disease free survival and overall survival were estimated using the Kaplan-Meier method. The log-rank test was used to assess differences between groups. RESULTS: The median follow-up was 7.2 years. The overall survival is similar within the two groups, being 91.4% and 91.3% at 10-yr in the study group and in the control group respectively. The disease free survival is slightly lower in the oncoplastic group (69 vs.73.1% at 10-yr). The difference is not statistically significant. DISCUSSION: We have compared a large series of primary breast cancer patients that have undergone oncoplastic surgery (454) with a control group (908) and they were followed for a prolonged period of time. It provides the best available evidence to suggest that oncoplastic surgery is a safe and reliable treatment option for the managing of invasive breast cancer.


Asunto(s)
Neoplasias de la Mama/mortalidad , Neoplasias de la Mama/cirugía , Mamoplastia/mortalidad , Mamoplastia/métodos , Mastectomía Segmentaria/métodos , Recurrencia Local de Neoplasia/parasitología , Adulto , Anciano , Neoplasias de la Mama/patología , Estudios de Casos y Controles , Supervivencia sin Enfermedad , Femenino , Estudios de Seguimiento , Humanos , Estimación de Kaplan-Meier , Mastectomía Segmentaria/mortalidad , Persona de Mediana Edad , Invasividad Neoplásica/patología , Recurrencia Local de Neoplasia/mortalidad , Recurrencia Local de Neoplasia/cirugía , Estadificación de Neoplasias , Seguridad del Paciente , Modelos de Riesgos Proporcionales , Estudios Retrospectivos , Medición de Riesgo , Estadísticas no Paramétricas , Análisis de Supervivencia , Factores de Tiempo , Resultado del Tratamiento
8.
Oncogene ; 9(11): 3199-204, 1994 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-7936642

RESUMEN

We have recently demonstrated a large induction of keratinocyte growth factor expression in dermal fibroblasts during wound healing. To identify possible mediators of KGF induction, we have now analysed the regulation of KGF expression in vitro in cultured murine and human fibroblasts. Here we demonstrate that KGF mRNA and protein expression is low in quiescent fibroblasts but is strongly induced upon serum stimulation. This induction can be mediated by at least two different intracellular pathways involving protein kinase C or cAMP-dependent kinases. Our finding that induction of KGF expression by serum is independent of de novo protein synthesis demonstrates, that KGF is the product of a primary response gene. The stimulatory effect of serum on KGF expression is likely to be a combinatorial effect of different mitogens, since several purified serum growth factors also stimulated KGF expression but to a lesser extent compared to serum. Furthermore, we also found a strong KGF induction by interleukin-1 beta, tumor necrosis factor-alpha and interleukin-6, cytokines which are released by polymorphonuclear leukocytes and activated macrophages during wound healing. These data suggest that serum which is released upon hemorrhage as well as pro-inflammatory cytokines might be responsible for the KGF induction in vivo during skin repair.


Asunto(s)
Citocinas/fisiología , Factores de Crecimiento de Fibroblastos , Sustancias de Crecimiento/biosíntesis , Sustancias de Crecimiento/fisiología , Células 3T3 , Animales , Células Cultivadas , Factor 10 de Crecimiento de Fibroblastos , Factor 7 de Crecimiento de Fibroblastos , Fibroblastos/metabolismo , Sustancias de Crecimiento/sangre , Sustancias de Crecimiento/genética , Humanos , Inflamación/inmunología , Interleucina-1/fisiología , Interleucina-6/fisiología , Ratones , Ratones Endogámicos BALB C , ARN Mensajero/biosíntesis , Transducción de Señal , Transcripción Genética , Factor de Necrosis Tumoral alfa/fisiología
9.
Biochim Biophys Acta ; 1385(2): 221-8, 1998 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-9655909

RESUMEN

Activation of the coenzyme ThDP was studied by measuring the kinetics of deprotonation at the C2 carbon of thiamin diphosphate in the enzymes pyruvate decarboxylase, transketolase, pyruvate dehydrogenase complex, pyruvate oxidase, in site-specific mutant enzymes and in enzyme complexes containing coenzyme analogues by proton/deuterium exchange detected by 1H-NMR spectroscopy. The respective deprotonation rate constant is above the catalytic constant in all enzymes investigated. The fast deprotonation requires the presence of an activator in pyruvate decarboxylase from yeast, showing the allosteric regulation of this enzyme to be accomplished by an increase in the C2-H dissociation rate of the enzyme-bound thiamin diphosphate. The data of the thiamin diphosphate analogues and of the mutant enzymes show the N1' atom and the 4'-NH2 group to be essential for the activation of the coenzyme and a conserved glutamate involved in the proton abstraction mechanism of the enzyme-bound thiamin diphosphate.


Asunto(s)
Piruvato Descarboxilasa/metabolismo , Complejo Piruvato Deshidrogenasa/metabolismo , Piruvato Oxidasa/metabolismo , Tiamina Pirofosfato/metabolismo , Transcetolasa/metabolismo , Regulación Alostérica , Escherichia coli/enzimología , Cinética , Lactobacillus/enzimología , Resonancia Magnética Nuclear Biomolecular , Levaduras/enzimología
10.
J Phys Chem B ; 109(23): 11572-9, 2005 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-16852420

RESUMEN

The effect of water content on the physicochemical properties of the amorphous regions in cotton were investigated by measuring the electron paramagnetic resonance (EPR) of TEMPOL nitroxide radicals, deposited in cotton at different loadings, as a function of the relative humidity (RH) and temperature. Three different components contribute differently to the experimental EPR spectra, corresponding to (a) mobile radicals absorbed in the bulk amorphous region, (b) slow moving radicals adsorbed on the crystallite surfaces in cotton, and (c) aggregated radicals. These components were analyzed by means of computer-aided simulations of the line shapes and simplified line width methods. Polarity and mobility parameters were extracted from the analysis of the spectra. For all loadings and temperatures, the polarity suddenly dropped when the water content fell below approximately 3 wt %, i.e., when water was removed from the bulk amorphous regions. At the lowest loading (2 x 10(-5) mol kg(-1)), the spectra were independent of the RH, and only mobile radicals were observed. At intermediate loading (10(-4)-10(-3) mol kg(-1)) both mobile (fast) and adsorbed (slow) moving radicals were present, the fraction of which depended on the RH. The mobility of the adsorbed and mobile radical signals was smaller at higher loadings, indicating microdomains of different character. The temperature dependence of the rotational correlation times provided the activation energies, which were much lower than in liquids. An equilibrium exists between the mobile and the adsorbed radicals. The temperature dependence of the equilibrium constant, K, gave the enthalpy and the entropy of the adsorption process. At low RH, the enthalpy and the entropy values indicated a simple adsorption process. At 10(-3) mol kg(-1), the values were independent of the RH, but at low loadings the values increased with the increase in the RH, which suggested a displacement of adsorbed water by the radicals at high water content. At loadings above 10(-3) mol kg(-1), signals from radicals strongly interacting via spin exchange were observed, which are assigned to aggregated radicals; simulation of the spectra gave an activation energy of 13 kJ mol(-1) for the spin exchange process. These effects are rationalized on the basis of microdomains of different character within cotton, reflecting the variation in pore sizes (0.5-8 nm) and the relaxation behavior of the cellulose chains.


Asunto(s)
Fibra de Algodón , Humedad , Textiles , Agua/análisis , Espectroscopía de Resonancia por Spin del Electrón , Marcadores de Spin
11.
Exp Hematol ; 9(4): 346-54, 1981 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-7016564

RESUMEN

Recovery of the hematopoietic system up to 35 days following whole body irradiation of mice was investigated by measuring the repopulation ability of femoral bone marrow in irradiated recipients. The assay was performed five days after transfusion by testing for incorporation of 125iodo-deoxyuridine (125IUdR) into DNA of femoral marrow and spleen. The DNA incorporating cells are progeny of transfused stem cells or early precursors. For non-irradiated donors 125IUdR incorporation in the recipient spleens was proportional to the number of transfused cells between 0.05-1.0 x 10(6)/mouse but decreased with larger grafts (5-30 x 10(6). Yet, in the femur 125IUdR incorporation remained proportional over the range of 0.5-30 x 10(6) transfused cells. Recovery was discontinuous and not complete 35 days after irradiation. A possible explanation is injury to stem cells that still permits these cells to produce progeny within a milieu of high proliferation stimulus.


Asunto(s)
Células Madre Hematopoyéticas/efectos de la radiación , Animales , Trasplante de Médula Ósea , División Celular , Ensayo de Unidades Formadoras de Colonias , Femenino , Fémur/citología , Rayos gamma , Idoxuridina/metabolismo , Radioisótopos de Yodo , Ratones , Quimera por Radiación , Bazo/citología , Factores de Tiempo
12.
J Invest Dermatol ; 103(4): 469-73, 1994 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-7930669

RESUMEN

We have recently demonstrated induction of expression of several members of the fibroblast growth factor family during wound healing, particularly for keratinocyte growth factor, which was more than 150-fold induced within 24 h after injury. To assess whether wound-healing disorders are associated with a defect in fibroblast growth factor regulation, we have now investigated the expression of these mitogens as well as their receptors in normal and wounded skin of genetically diabetic db/db mice, which are characterized by their impaired wound healing. We demonstrate that induction of keratinocyte growth factor expression in these mice is significantly reduced and delayed compared to normal mice. Induction of acidic fibroblast growth factor (FGF) and basic FGF expression was earlier in diabetic mice than in normal mice, but by 3 d after injury expression of these mitogens had already returned to the basal levels. In contrast, elevated levels of acidic FGF and basic FGF transcripts were detected within the first 5 d in wounds from normal mice. Thus, FGFs seem to be expressed in a limited fashion in the wound tissue of db/db mice during the period when re-epithelialization and granulation tissue formation normally occur. These findings provide an explanation for the beneficial effect of exogenous FGF in the treatment of impaired wound healing in these animals and suggest that induction of KGF early in repair may be critical for the rapid re-epithelialization in normal wound healing.


Asunto(s)
Diabetes Mellitus Experimental/genética , Factores de Crecimiento de Fibroblastos , Sustancias de Crecimiento/fisiología , Cicatrización de Heridas/fisiología , Animales , Diabetes Mellitus Experimental/fisiopatología , Factor 10 de Crecimiento de Fibroblastos , Factor 7 de Crecimiento de Fibroblastos , Sustancias de Crecimiento/genética , Queratinocitos/química , Ratones , Ratones Endogámicos C57BL , ARN Mensajero/análisis , Receptores de Factores de Crecimiento de Fibroblastos/fisiología
13.
Biol Psychiatry ; 45(9): 1221-5, 1999 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-10331116

RESUMEN

BACKGROUND: Increased levels of phosphodiesters (PDE%) and reduced relative concentrations of phosphomonoesters (PME%) have been reported in unmedicated schizophrenics, whereas findings in brain of medicated patients were not consistent. METHODS: We determined in vivo the metabolism of phospholipids and high-energy phosphates in the left and right frontal lobes of 8 patients with schizophrenia using 31P-magnetic resonance spectroscopy (31P-MRS). Serial investigations were performed first after a neuroleptic-free period (mean 7.5 +/- 1.9 days) and second, after neuroleptic treatment (mean 20.6 +/- 11.1 days). RESULTS: PDE% increased significantly in the left frontal lobe (32.0 +/- 5.9% versus 36.9 +/- 5.6%, p = .009) after medication. All other parameters showed no significant differences. CONCLUSIONS: Our study suggests that neuroleptics do not decrease phospholipase A2 activity in schizophrenia. Individual neuroleptics may have different effects on phospholipase A2 activity as indicated by animal studies. An influence of neuroleptics on high-energy phosphates cannot be confirmed by our data.


Asunto(s)
Hidrolasas Diéster Fosfóricas/metabolismo , Esquizofrenia/metabolismo , Adulto , Femenino , Humanos , Estudios Longitudinales , Espectroscopía de Resonancia Magnética , Masculino , Persona de Mediana Edad , Escalas de Valoración Psiquiátrica , Psicología del Esquizofrénico
14.
Biol Psychiatry ; 44(6): 399-404, 1998 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-9777168

RESUMEN

BACKGROUND: In a preliminary study we found decreased phosphodiester (PDE)% values and an increased phosphomonoester (PME)/phosphodiester ratio in the dorsolateral prefrontal region (DLPFR) of 13 chronic schizophrenics vs. 14 controls using 31phosphorus magnetic resonance spectroscopy (31P-MRS). Since these results are in contrast to the findings of other groups, we increased our study group to a total of 50 chronic schizophrenics on stable neuroleptic medication and 36 controls to minimize the possibility of a chance result due to small sample size. METHODS: An image-selected in vivo 31P-MRS method on a Philips Gyroscan ACS II scanner working at 1.5 T was used. RESULTS: We could confirm our earlier findings of decreased PDE% levels in schizophrenics. Additionally, we found phosphocreatine (PCr)% and PCr/adenosine triphosphate (ATP) to be increased in the schizophrenics. While no association between PME% and PDE% with neuroleptic medication was found, ATP% correlated positively and PCr/ATP negatively with the chlorpromazine equivalent dose. CONCLUSIONS: The decreased PDE% levels might be characteristic only for chronic, neuroleptic-treated patients. The finding of altered high-energy phosphate levels can be interpreted as an indication of decreased energy-demanding processes in the DLPFR of the investigated patients compared to controls.


Asunto(s)
Química Encefálica , Corteza Prefrontal/metabolismo , Esquizofrenia/metabolismo , Adenosina Trifosfato/metabolismo , Adulto , Femenino , Humanos , Espectroscopía de Resonancia Magnética , Masculino , Organofosfatos/metabolismo , Fosfocreatina/metabolismo , Corteza Prefrontal/química , Escalas de Valoración Psiquiátrica , Esquizofrenia/fisiopatología
15.
FEBS Lett ; 299(2): 163-5, 1992 Mar 09.
Artículo en Inglés | MEDLINE | ID: mdl-1312040

RESUMEN

Decarboxylation of pyruvate by pyruvate decarboxylase (EC 4.1.1.1) was performed in a reaction mixture containing 50% deuterium. The isolated product, acetaldehyde, was investigated directly by 1H NMR and by mass spectrometry after conversion to the 2,4-dinitrophenyl hydrazone. The protium content of 56% at acetaldehyde C1 demonstrates a specific protonation of the corresponding intermediate by the enzyme. Proton inventory studies and enzyme modification indicate the 4' amino group of the coenzyme, thiamine pyrophosphate, in an immonium structure being a possible proton donor. A 'partially concerted' mechanism is suggested for the reaction steps following the decarboxylation.


Asunto(s)
Piruvato Descarboxilasa/química , Acetaldehído/química , Cinética , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Protones , Saccharomyces cerevisiae/enzimología
16.
FEBS Lett ; 314(1): 101-3, 1992 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-1451797

RESUMEN

The pH dependence of the quaternary structure of pyruvate decarboxylase (EC 4.1.1.1) has recently been discovered [(1990) FEBS Lett. 266, 17-20; (1992) Biochemistry (in press)]. In the present study we have investigated the change in quaternary structure by observing the binding of the cofactor, thiamine pyrophosphate, using 31P NMR spectroscopy. The dissociation of the native tetramers into dimers when increasing the pH coincides with a weaker binding of the cofactor and loss of enzyme activity. The results provide further evidence that thiamine pyrophosphate is bound primarily via the beta-phosphate moiety. In addition, a phosphoserine has been discovered in two of the four subunits.


Asunto(s)
Piruvato Descarboxilasa/metabolismo , Tiamina Pirofosfato/metabolismo , Sitios de Unión , Concentración de Iones de Hidrógeno , Espectroscopía de Resonancia Magnética , Isótopos de Fósforo , Conformación Proteica , Piruvato Descarboxilasa/efectos de los fármacos , Saccharomyces/enzimología , Tiamina Pirofosfato/farmacología
17.
FEBS Lett ; 441(3): 404-6, 1998 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-9891980

RESUMEN

Replacement of tryptophan 392 located in the active site cavity of pyruvate decarboxylase (PDC; EC 4.1.1.1) from Zymomonas mobilis by methionine or glutamine yields enzymes with smaller catalytic constants of 8.5 s(-1) and 3.6 s(-1) at 4 degrees C, compared to that of the wild-type enzyme (17 s(-1)). The rate constants of the H/D exchange at the C2 of the coenzyme thiamine diphosphate have been determined to be 130 s(-1) for the wild-type enzyme, 56 s(-1) for the methionine and 30 s(-1) for the glutamine mutant, respectively. A group with a pKa of about 5 has been identified to be essential for C2 deprotonation of the enzyme-bound thiamine diphosphate from the pH dependence of the H/D exchange.


Asunto(s)
Piruvato Descarboxilasa/metabolismo , Tiamina Pirofosfato/metabolismo , Zymomonas/enzimología , Concentración de Iones de Hidrógeno , Cinética , Mutación , Protones , Piruvato Descarboxilasa/química , Piruvato Descarboxilasa/genética
18.
FEBS Lett ; 266(1-2): 17-20, 1990 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-2194837

RESUMEN

Structure and activation pattern of pyruvate decarboxylase (PDC) from yeast was studied by synchrotron radiation X-ray solution scattering. The results give a direct proof that the reversible deactivation of PDC at pH 8.0 is accompanied by the dissociation of the tetrameric holoenzyme into dimeric halves. The kinetics of this process was followed. At pH 6.5 the dimeric halves reassociate to a tetramer even in the absence of cofactors. The changes of the scattering pattern upon binding of the substrate-like activator pyruvamide indicate that the structure expands in the course of the enzyme activation.


Asunto(s)
Carboxiliasas , Piruvato Descarboxilasa , Apoenzimas , Activación Enzimática , Magnesio/metabolismo , Unión Proteica , Conformación Proteica , Piruvatos/metabolismo , Piruvatos/farmacología , Saccharomyces cerevisiae/enzimología , Dispersión de Radiación , Tiamina Pirofosfato/metabolismo , Factores de Tiempo , Rayos X
19.
Neuromuscul Disord ; 2(5-6): 389-96, 1992.
Artículo en Inglés | MEDLINE | ID: mdl-1300187

RESUMEN

Malignant hyperthermia (MH) is a pharmacogenetic myopathy triggered by a variety of anaesthetic agents and muscle relaxants. In humans, susceptibility to MH is inherited as an autosomal dominant trait, and susceptible patients do not show a clinically relevant myopathy unless having suffered from a MH crisis. Homozygosity for the MHS trait is thought to be an uncommon finding, and so far only a few cases of patients suggested to be homozygous for MH on the basis of pedigree information were reported and described as having a more severe form of this condition resulting in clinical symptoms also in the absence of triggering agents. We report clinical findings in a patient with chronic myopathy beginning at the age of 2 yr and associated with a number of unique features, the most important being a family history of MHS present in both parents. She became symptomatic with marked muscular weakness and elevated serum CK levels. A muscle biopsy showed a distinct enlargement and increase of muscle mitochondria. In the in vitro contracture test the patient's muscle responded with unusually high contractures already at basal levels of triggering agents indicating a particularly severe MHS condition. DNA markers for the MHS1 locus, described previously on chromosome 19q12-13.2 in Irish and Canadian pedigrees, could not be used to confirm her homozygous state because our molecular genetic studies had previously excluded the MHS trait in this pedigree from this locus.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Hipertermia Maligna/genética , Enfermedades Musculares/genética , Preescolar , Enfermedad Crónica , Creatina Quinasa/sangre , Susceptibilidad a Enfermedades , Femenino , Humanos , Técnicas In Vitro , Hipertermia Maligna/patología , Contracción Muscular/fisiología , Músculos/patología , Enfermedades Musculares/patología , Mutación , Linaje
20.
Transplantation ; 56(5): 1114-8, 1993 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-8249110

RESUMEN

Eight patients with chronic myeloid leukemia relapse after allogeneic BMT were treated with IFN-alpha and buffy coat transfusions (BC) of the bone marrow donor. The antileukemic effect of this treatment was directly demonstrated in 4 patients by the disappearance of Philadelphia chromosome-positive metaphases or the loss of detectable BCR-ABL transcripts by polymerase chain reaction. In 2 patients in whom cytogenetic or polymerase chain reaction analysis was not performed, a change in hemopoietic chimerism with recurrence of donor-type hemopoiesis was demonstrated. Two patients, both treated in advanced stages of hematological relapse after BMT, did not respond. However, severe side effects of the treatment were observed: graft-versus-host disease (GVHD) occurred in 5 patients. Two of these patients progressed to severe chronic GVHD and 1 patient ultimately died of this complication. GVHD occurred in 5 of the 6 responding patients; one patient responded without developing clinical symptoms of GVHD. Six patients developed bone marrow hypoplasia after IFN/BC treatment, and pancytopenia occurred in 4 patients. None of these 4 patients recovered spontaneously and 2 patients died of complications of pancytopenia (cerebral bleeding, infection). Our results demonstrate that treatment of chronic myeloid leukemia relapse with IFN and BC transfusions is highly effective in patients with relapse in chronic phase. The occurrence of GVHD and pancytopenia, however, resulted in a high treatment-associated morbidity and mortality. Whereas a response to treatment was observed in 1 patient without GVHD, indicating that GVHD and a graft-versus-leukemia effect may be clinically separable, bone marrow hypoplasia occurred in all responding patients.


Asunto(s)
Trasplante de Médula Ósea , Interferón-alfa/uso terapéutico , Leucemia Mielógena Crónica BCR-ABL Positiva/terapia , Transfusión de Leucocitos , Adulto , Femenino , Enfermedad Injerto contra Huésped/etiología , Humanos , Masculino , Persona de Mediana Edad , Recurrencia , Trombocitopenia/etiología , Trasplante Homólogo
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