RESUMEN
We report a comprehensive de Haas-van Alphen (dHvA) study of the heavy-fermion material CeRhIn_{5} in magnetic fields up to 70 T. Several dHvA frequencies gradually emerge at high fields as a result of magnetic breakdown. Among them is the thermodynamically important ß_{1} branch, which has not been observed so far. Comparison of our angle-dependent dHvA spectra with those of the non-4f compound LaRhIn_{5} and with band-structure calculations evidences that the Ce 4f electrons in CeRhIn_{5} remain localized over the whole field range. This rules out any significant Fermi-surface reconstruction, either at the suggested nematic phase transition at B^{*}≈30 T or at the putative quantum critical point at B_{c}≃50 T. Our results rather demonstrate the robustness of the Fermi surface and the localized nature of the 4f electrons inside and outside of the antiferromagnetic phase.
RESUMEN
BACKGROUND: Chronic red blood cell exchanges (RBCXs) are frequently used to prevent complications in patients with sickle cell anemia, but the scarcity of matched red blood cell packs (RBCPs) is a serious concern. The main goal of this study was to compare the number of RBCPs used during RBCXs between the Spectra Optia (SO) device (with the automatic depletion step) and the former Cobe Spectra (CSP) device. STUDY DESIGN AND METHODS: The performances and safety of 300 SO sessions using the automatic depletion step (SO/DE) in 50 patients with sickle cell anemia under a chronic transfusion program over a 1-year period were prospectively analyzed. The numbers of RBCPs saved using this protocol compared to the SO device without depletion and to the CSP device were determined. RESULTS: The SO/DE protocol appeared to be safe, as only 5% and 17% of the sessions were characterized by a significant decrease in blood pressure and increase in heart rate (grade 2 adverse events), respectively. Postapheresis hematocrit and fraction of cells remaining reached expected values. The SO/DE protocol required 16% fewer RBCPs compared to SO without depletion, allowing a mean saving of 12 RBCPs per patient and per year and 13% fewer compared to CSP device. Interestingly, the saving was more important for patients with high total blood volume and/or high preapheresis hematocrit. CONCLUSION: The SO/DE protocol is an efficient, safe and cost-effective procedure for patients with sickle cell anemia under a chronic transfusion program.
Asunto(s)
Anemia de Células Falciformes/terapia , Transfusión de Eritrocitos/métodos , Eritrocitos/citología , Adolescente , Adulto , Niño , Femenino , Humanos , Masculino , Estudios Prospectivos , Adulto JovenRESUMEN
Red blood cell exchange (RBCX) is a standard option for treating or preventing complications in patients with sickle cell disease (SCD). According to the patient's blood volume, the amounts of red blood cells (RBC) to be exchanged and the practices of the apheresis and clinical teams, such treatment requires numerous red blood cell units (RBCUs) (3-15 RBCUs per procedure). To perform RBCXs safely and prevent the risk of alloimmunization, appropriate RBCUs must be selected and transfused to replace the sickled RBCs. Understanding of alloimmunization in patients with SCD strengthened the development of recommendations for preventing the risk of alloimmunization. This review describes the alloimmunization risk, the methods used to decrease the risk, and our own experience.
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Anemia de Células Falciformes/terapia , Transfusión de Eritrocitos/métodos , Eritrocitos/metabolismo , Anemia de Células Falciformes/patología , HumanosRESUMEN
OBJECTIVES: Evaluation of a blood storage of six concentrates red blood cells of groupe O RH:-1KEL:-1 in a surgical emergency treatment center. PATIENTS AND METHODS: All patients transfused with this concentrates; main points of utilisation are analysed. CONCLUSION: The concentrates, used by the anaesthesiologists, are part of the treatment strategy care in case of severe bleeding.
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Sistema del Grupo Sanguíneo ABO , Conservación de la Sangre , Transfusión de Eritrocitos/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Pérdida de Sangre Quirúrgica/mortalidad , Eritrocitos , Femenino , Francia/epidemiología , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Hematopoietic stem cell (HSC) allogeneic transplantation is now commonly used as a therapeutic tool in patients with certain types of hematologic malignancies. Such patients, on account of severe pre-graft conditioning regimens, present with severe marrow aplasia justifying specific transfusion care. Given a complex immunological situation (immediately after transplantation, co-existence of two cell populations with different immunohematological characteristics), transfusion protocols must rest on clear and well-defined recommendations. Recent transfusion recommendations in settings of HSC allogeneic transplantation have defined criteria for the choice of blood products (red blood cell concentrates, plasma and platelet concentrates) depending on recipient and graft immunohematological characteristics (minor/major/mixed ABO compatibility/incompatibility and time of transplantation). Transfusion instructions are summarized in a synthesis document entitled : "Instructions for transfusion following HSC allogeneic transplantation". This document specifies the immunohematological characteristics of blood products and various transfusion protocols (systematic irradiation, negative CMV, etc.). This document is used by the teams who distribute blood products, for selection purposes, as well as by the medical transfusion team when they perform ultimate pre-transfusion control steps.
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Transfusión Sanguínea/métodos , Trasplante de Células Madre Hematopoyéticas , Humanos , Leucemia/terapia , Linfoma/terapia , Mieloma Múltiple/terapia , Síndromes Mielodisplásicos/terapia , Neoplasias/terapia , Trasplante HomólogoRESUMEN
The aim of the study was to evaluate the outcome of unrelated bone marrow donor (UBMD) searches initiated for 174 children between 1986 and 1997. Seven patients were registered twice so that a total of 181 UBMD searches took place. At the time of registration, patients suffered from hematological malignancies (n = 121), non-malignant hemopathies (n = 26) and inborn errors (n = 34). Forty-five of the patients (26%) were given transplants from unrelated donors of whom 26 (58%) were HLA-mismatched transplants. Our strategy accepted HLA mismatches at the time of donor selection, using Thymoglobuline as part of the conditioning regimen. Of the 45 patients given unrelated donor transplants, overall survival was 60% at 3 years and concerned 27 patients of whom 14 were from HLA-mismatched donors. Disease-free survival for hematological malignancies was 65% in HLA-matched transplants and 50% in HLA-mismatched transplants. For some patients (16%) urgency led us to use alternative options: non-identical related donor (n = 14), autograft (n = 10), related cord blood transplant (n = 4). For others, UBMD searches were stopped because of favorable evolution (n = 29), death (n = 24), disease progression (n = 22) or other reasons (n = 21). By the end of the follow-up period, 88 patients had died (50%), 75 (43%) are currently alive with or without being transplanted of whom eight are still having active searches and 11 are no longer contactable. In conclusion, in severe disease in children, an immediate transplant from a partially matched donor might be preferable to a prolonged search for a full match. Consequently, this strategy increases the number of patients for whom a suitable donor can be found. We have chosen this option in order not to delay BMT; in so doing we have obtained encouraging results which include high overall survival, low incidence of acute GVHD grade III-IV and low percentage of relapse even in mismatched pairs.
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Trasplante de Médula Ósea , Enfermedades Hematológicas/terapia , Neoplasias Hematológicas/terapia , Prueba de Histocompatibilidad , Donadores Vivos , Errores Innatos del Metabolismo/terapia , Obtención de Tejidos y Órganos/organización & administración , Adolescente , Trasplante de Médula Ósea/inmunología , Trasplante de Médula Ósea/mortalidad , Niño , Preescolar , Femenino , Francia , Humanos , Lactante , Masculino , Sistema de Registros , Tasa de Supervivencia , Resultado del TratamientoRESUMEN
Los hemangiomas son los tumores benignos más frecuentes de la infancia, suelen localizarse en cabeza y tronco, y en la mayoría de los casos tienden a involucionar espontáneamente. Los hemangiomas labiales tienen mayor riesgo de producir deformidades, cicatrices residuales o ulceraciones. Una minoría de casos, bien por su tamaño, su ubicación o su evolución complicada, requieren tratamiento, empleándose tradicionalmente corticoides orales. En los últimos años han aparecido casos tratados con propranolol oral con excelentes resultados. Presentamos un lactante varón de tres meses, sin antecedentes de interés, que presentaba un hemangioma en el labio superior que le dificultaba la succión y le provocaba una deformidad estética. Tras descartar patología asociada, a los cuatro meses comenzó tratamiento ambulatorio con propranolol oral en dosis inicial de 1,5 mg/kg/día, con buenos resultados y sin complicaciones. La evolución fue satisfactoria, disminuyendo el tamaño y el color de la lesión. Consideramos que el propranolol es una opción terapéutica eficaz y segura, y aunque son necesarios estudios clínicos amplios en los que el mecanismo de acción, la dosis y la duración del tratamiento queden aclarados, queremos destacar la figura del pediatra de Atención Primaria en la detección de posibles efectos adversos, en el seguimiento del paciente y en el apoyo a la familia (AU)
Hemangiomas are the most common benign tumours in childhood, usually located in the head and neck, and most of them suffer a spontaneous regression. Lip hemangiomas have a higher risk of causing deformities, residual scarring or ulceration. A minority of cases, either because of size, location or their complicated evolution, require therapy, traditionally using oral corticosteroids. In recent years, excellent results have been obtained in cases treated with oral propranolol. We present the case of a 3-month-old male infant, with no history of interest, who had a hemangioma in his upper lip that made suction difficult and produced an aesthetic deformity. After ruling out associated pathology, at the age of 4 months our patient began outpatient treatment with oral propranolol with an initial dose of 1.5 mg/kg/day, with good results and without complications. The evolution was satisfactory, and the size and colour of the injury were reduced. We believe that propranolol is an effective and safe therapeutic option, and although comprehensive clinical studies are needed in which the mechanism of action, dosage and duration of treatment are clarified, we would like to highlight the important role of the primary care pediatrician in the detection of possible adverse effects, in patient monitoring, and in family support (AU)
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Humanos , Masculino , Lactante , Hemangioma/diagnóstico , Hemangioma/tratamiento farmacológico , Propranolol/administración & dosificación , Propranolol/uso terapéutico , Labio , Labio/lesiones , Labio/patología , Atención Primaria de Salud/métodos , Atención Primaria de Salud/estadística & datos numéricos , Frecuencia Cardíaca , Frecuencia Cardíaca/fisiologíaRESUMEN
Acetylcholinesterase from cobra (Naja naja oxiana) venom has been purified by affinity chromatography to an homogeneous state, as ascertained by sodium dodecylsulfate/polyacrylamide gel electrophoresis and sedimentation analysis. The specific activity of the preparation was 5000 IU/mg with acetylcholine as substrate. Unlike acetylcholinesterases from insoluble cell structures, the native molecule of the cobra venom enzyme consists of a single polypeptide chain of molecular weight 67,000 +/- 2000. At high enzyme concentrations (greater than 0.2 mg/ml, greater than 1 microM) and ionic strength 0.1 M, it reversibly tends to form higher-molecular-weight 7.1-S aggregates. Despite the apparent structural simplicity of the venom acetylcholinesterase, the disc electrophoresis and isoelectric focusing experiments revealed that the enzyme exists in a number of forms with a common molecular weight but with different isoelectric points. Neuraminidase treatment did not reduce the number of the forms.
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Acetilcolinesterasa/aislamiento & purificación , Venenos Elapídicos , Animales , Sustancias Macromoleculares , Peso Molecular , Ácidos Siálicos/análisisRESUMEN
Crude tRNA isolated from rat liver by the method of Rogg et al. (Biochem. Biophys. Acta 195, 13-15 1969) contains N6-dimethyladenosine (m6-2A) and was therefore fractionated in order to identify the m6-2A-containing RNAs. A unique species of RNA was purified which contained all the m62A present in the crude tRNA. Sequence analysis by postlabeling with gamma-32p-ATP and polynucleotide kinase revealed that this RNA represents the 32 nucleotides AAGGUUUC(C)U GUAGGUGm62Am62ACCUGCGGAAGGAUC from position 5 to 36 of the 3' terminus of ribosomal 18S RNA. The 36 nucleotide long sequence from the 3' end of rat liver 18S rRNA exhibits extensive homology with the corresponding sequence of E. coli 16S rRNA and with the 21 nucleotide long 3' terminal sequence so far known from Saccharomyces carlsbergensis 17S rRNA. A heterogeneity in this sequence provides the first evidence on the molecular level for the existence of (at least) two sets of redundant ribosomal 18S RNA genes in the rat.
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Nucleótidos de Adenina/análisis , ARN Ribosómico/aislamiento & purificación , Animales , Secuencia de Bases , Hígado/análisis , Peso Molecular , ARN Ribosómico/análisis , RatasRESUMEN
The use of arterial or venous allografts for vascular reconstruction was first reported in 1951, but long-term results have been disappointing. Rejection and inappropriate methods of preservation are the main reasons for failure. A successful solution to this problem could be achieved by programmed cryopreservation with cryoprotectant. Our study had two aims: to define the biomechanical properties of cryopreserved arterial allografts and to study their histologic appearance. Arteries were removed as part of a protocol for multiorgan harvesting for transplantation. Cryopreservation was performed within the first 24 hours after harvesting. Programmed cryopreservation with 15% dimethyl sulfoxide (cryoprotectant) was used. Mechanical testing was done immediately after thawing. Two groups were tested: a control group of fresh aortas and a group of cryopreserved aortas. Axial and circumferential strips were tested. High strain modulus and stress and strain characteristics were calculated for each strip. There was no statistically significant difference between the mechanical properties of fresh and cryopreserved human descending thoracic aortas. Biochemical tests were performed in the preservative solution at 1 and 7 days in both groups. There was no statistically significant difference between the two groups at day 1 or day 7 (p > 0.05). Histologic studies before and after arterial cryopreservation included standard and electron microscopy and showed that arteries had normal structure after cryopreservation. These results confirm that programmed cryopreservation with cryoprotectant does not alter the molecular or geometric configuration of collagen or elastic fibers. Endothelial cells were still present, however, their viability and function were not assessed.(ABSTRACT TRUNCATED AT 250 WORDS)
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Arterias/trasplante , Criopreservación , Aorta/trasplante , Brazo/irrigación sanguínea , Arterias/química , Arterias/patología , Arterias/fisiología , Fenómenos Biomecánicos , Creatina Quinasa/análisis , Elasticidad , Humanos , Concentración de Iones de Hidrógeno , Técnicas In Vitro , L-Lactato Deshidrogenasa/análisis , Concentración Osmolar , Proteínas/análisis , Estrés Mecánico , Trasplante HomólogoRESUMEN
One of the lysine transfer RNAs of rabbit liver is shown to contain 2'-O-methyl ribothymidine in place of ribothymidine. This represents the first demonstration of the presence of 2'-O-methyl ribothymidine in a nucleic acid.
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ARN de Transferencia de Lisina/química , Uridina/análogos & derivados , Animales , Cromatografía en Capa Delgada , Hígado/química , ARN de Transferencia de Lisina/aislamiento & purificación , Conejos , Espectrofotometría Ultravioleta , Uridina/análisis , Uridina/aislamiento & purificaciónRESUMEN
The viroid of the potato spindle tuber disease (PSTV) is a covalently closed ring of 359 ribonucleotides. As a result of intramolecular base pairing, a serial arrangement of double-helical sections and internal loops form a unique rod-like secondary structure. PSTV is the first pathogen of a eukaryotic organism for which the complete molecular structure has been established.
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Virus de Plantas/genética , ARN Viral , Secuencia de Bases , Codón , Conformación de Ácido Nucleico , Virus de Plantas/ultraestructura , Biosíntesis de ProteínasRESUMEN
The complete nucleotide sequence of citrus exocortis viroid (CEV, propagated in Gymura) and chrysanthemum stunt viroid (CSV, propagated in Cineraria) has been established, using labelling in vitro and direct RNA sequencing methods and a new screening procedure for the rapid selection of suitable RNA fragments from limited digests. The covalently closed circular single-stranded viroid RNAs consist of 371 (CEV) and 354 (CSV) nucleotides, respectively. As previously shown for potato spindle tuber viroid (PSTV, 359 nucleotides), CEV and CSV also contain a long polypurine sequence. Maximal base-pairing of the established CEV and CSV sequences results in an extended rod-like secondary structure similar to that previously established for PSTV and as predicted from detailed physicochemical studies of all these viroids. Although the three viroid species sequenced to date differ in size and nucleotide sequence, there is 60--73% homology between them. As PSTV, CEV and CSV also contain conserved complementary sequences which are separated from each other in the native secondary structure. We postulate that the resulting 'secondary' hairpins, being formed and observed in vitro during the complex process of thermal denaturation of viroid RNA, must have a vital, although yet unknown, function in vivo. The possible origin and function of viroids are discussed on the basis of the characteristic structural features and of a considerable homology with U1a RNA found for a region highly conserved in the three viroids.
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ARN Viral/análisis , Viroides/análisis , Secuencia de Bases , Chrysanthemum cinerariifolium , Citrus , Conformación de Ácido Nucleico , Desnaturalización de Ácido Nucleico , Enfermedades de las PlantasRESUMEN
The lysine isoacceptor tRNAs differ in two aspects from the majority of the other mammalian tRNA species: they do not contain ribosylthymine (T) in loop IV, and a 'new' lysine tRNA, which is practically absent in non-dividing tissue, appears at elevated levels in proliferating cells. We have therefore purified the three major isoaccepting lysine tRNAs from rabbit liver and the 'new' lysine tRNA isolated from SV40-transformed mouse fibroblasts, and determined their nucleotide sequences. Our basic findings are as follows. a) The three major lysine tRNAs (species 1, 2 and 3) from rabbit liver contain 2'-O-methylribosylthymine (Tm) in place of T. tRNA1Lys and tRNA2Lys differ only by a single base pair in the middle of the anticodon stem; the anticodon sequence C-U-U is followed by N-threonyl-adenosine (t6A). TRNA3Lys has the anticodon S-U-U and contains two highly modified thionucleosides, S (shown to be 2-thio-5-carboxymethyl-uridine methyl ester) and a further modified derivative of t6 A (2-methyl-thio-N6-threonyl-adenosine) on the 3' side of the anticodon. tRNA3Lys differs in 14 and 16 positions, respectively, from the other two isoacceptors. b) Protein synthesis in vitro, using synthetic polynucleotides of defined sequence, showed that tRNA2Lys with anticodon C-U-U recognized A-A-G only, whereas tRNA3Lys, which contains thio-nucleotides in and next to the anticodon, decodes both lysine codons A-A-G and A-A-A, but with a preference for A-A-A. In a globin-mRNA-translating cell-free system from ascites cells, both lysine tRNAs donated lysine into globin. The rate and extent of lysine incorporation, however, was higher with tRNA2Lys than with tRNA3Lys, in agreement with the fact that alpha-globin and beta-globin mRNAs contain more A-A-G than A-A-A- codons for lysine. c) A comparison of the nucleotide sequences of lysine tRNA species 1, 2 and 3 from rabbit liver, with that of the 'new' tRNA4Lys from transformed and rapidly dividing cells showed that this tRNA is not the product of a new gene or group of genes, but is an undermodified tRNA derived exclusively from tRNA2Lys. Of the two dihydrouridines present in tRNA2Lys, one is found as U in tRNA4Lys; the purine next to the anticodon is as yet unidentified but is known not be t6 A. In addition we have found U, T and psi besides Tm as the first nucleoside in loop IV.
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Transformación Celular Viral , Hígado/análisis , ARN de Transferencia , Virus 40 de los Simios , Animales , Secuencia de Bases , Línea Celular , Fibroblastos/análisis , Globinas/biosíntesis , Lisina , Ratones , Ratones Endogámicos BALB C , Oligorribonucleótidos/análisis , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , ARN de Transferencia/metabolismoRESUMEN
Optimal numbers of CD34(+) cells to be reinfused in patients undergoing peripheral blood progenitor cell (PBPC) transplantation after high-dose chemotherapy are still unknown. Hematologic reconstitution of 168 transplantations performed in patients with lymphoproliferative diseases was analyzed according to the number of CD34(+) cells reinfused. The number of days from PBPC reinfusion until neutrophil recovery (>1.0 x 10(9)/L) and unsustained platelet recovery (>50 x 10(9)/L) were analyzed in three groups defined by the number of CD34(+) cells reinfused: a low group with less than or equal to 2.5 x 10(6) CD34(+) cells/kg, a high group with greater than 15 x 10(6) CD34(+) cells/kg, and an intermediate group to which the former two groups were compared. The 22 low-group patients had a significantly delayed neutrophil (P < .0001) and platelet recovery (P < .0001). The 41 high-group patients experienced significantly shorter engraftment compared with the intermediate group with a median of 11 (range, 8 to 16) versus 12 (range, 7 to 17) days for neutrophil recovery (P = .003), and a median of 11 (range, 7 to 24) versus 14 (range, 8 to 180+) days for platelet recovery (P < .0001). These patients required significantly less platelet transfusions (P = .002). In a multivariate analysis, the amount of CD34(+) cells reinfused was the only variable showing significance for neutrophil and platelet recovery. High-group patients had a shorter hospital stay (P = .01) and tended to need fewer days of antibotic administration (P = .12). In conclusion, these results suggest that reinfusion of greater than 15 x 10(6) CD34(+) cells/kg after high-dose chemotherapy for lymphoproliferative diseases further shortens hematopoietic reconstitution, reduces platelet requirements, and may improve patients' quality of life.