RESUMO
INTRODUCTION: Diagnostic student radiographer attrition is reported at 14%, 6% higher than the average for higher education, however, little research has been undertaken on this subject. This study explored risk factors for attrition and strategies that enabled these to be overcome. METHODS: A two-phase study was undertaken. Phase one: data for 579 former student diagnostic radiographers (468 completers and 111 non-completers) from 3 English universities were analysed. Logistic regression was used to estimate odds ratios and 95% confidence intervals for completion based on individual characteristics. Phase two: content analysis of data from an online survey of 186 current UK student diagnostic radiographers exploring their experiences was undertaken. RESULTS: Phase one: Attrition was 19%. Increased age, non A-level entry qualifications and poor academic performance were predictors of attrition (p < 0.005). Phase two: Challenges reported by groups identified as 'at risk' showed that for mature students and those with non-traditional entry qualifications, external responsibilities/pressures and financial pressures were likely to be the greatest cause of attrition and for younger students with traditional qualifications, academic difficulty and excessive workload were most significant. Scientific learning and academic writing were identified as the most common academic difficulties by all groups. Poor mental health may also be a risk factor. CONCLUSION: Although characteristics were identified that increased the chance of attrition, the study concluded that attrition is most likely to be multi-factorial. Academic and personal support were identified as key in students continuing their studies when they considered leaving. Clinical placement experience is likely to influence continuation decisions. IMPLICATIONS FOR PRACTICE: Transparency around course expectations and academic requirements together with ensuring high quality clinical placements may assist in reducing attrition.
Assuntos
Escolha da Profissão , Radiografia , Evasão Escolar/estatística & dados numéricos , Estudantes de Ciências da Saúde/estatística & dados numéricos , Tecnologia Radiológica/educação , Adolescente , Adulto , Feminino , Humanos , Masculino , Risco , Reino Unido , Adulto JovemRESUMO
Graft failure, regimen-related toxicity and graft-versus-host disease (GVHD) are the critical barriers to unrelated donor transplants for aplastic anaemia (AA). We investigated the use of a novel conditioning regimen consisting of alemtuzumab (humanized CD52 antibody), fludarabine and cyclophosphamide in seven patients with AA, who underwent bone marrow transplant procedure using matched unrelated donors. The aetiology of AA was acquired (n=3), Fanconi's (n=3) and congenital (n=1). Median age was 13 years (range 8-35). All the donors were fully matched for HLA class I and II antigens using high-resolution typing. All the patients engrafted at a median of 18 days (range 13-35). Two patients died of transplant-related complications: one of adenovirus disease and the other developed extensive chronic GVHD of skin followed by cytomegalovirus (CMV) disease. Three patients developed Grade II acute GVHD disease (GVHD); none had Grade III-IV acute GVHD. Of the six evaluable patients, only one developed chronic GVHD. We conclude that this conditioning regimen for unrelated donor transplants for AA is sufficiently immunosuppressive to allow stable engraftment and appears to have a favourable impact on the incidence and severity of GVHD, warranting further investigation.
Assuntos
Anemia Aplástica/terapia , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Transplante de Medula Óssea/métodos , Doadores de Tecidos , Vidarabina/análogos & derivados , Adolescente , Adulto , Alemtuzumab , Anemia Aplástica/complicações , Anemia Aplástica/etiologia , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais Humanizados , Anticorpos Antineoplásicos/administração & dosagem , Transplante de Medula Óssea/efeitos adversos , Transplante de Medula Óssea/imunologia , Criança , Ciclofosfamida/administração & dosagem , Sobrevivência de Enxerto , Doença Enxerto-Hospedeiro/patologia , Teste de Histocompatibilidade , Humanos , Terapia de Imunossupressão , Incidência , Resultado do Tratamento , Vidarabina/administração & dosagemRESUMO
We have examined the effect of mast cell growth factor (MGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-3 (IL-3), singly or in combination, on the growth of normal and aplastic anemia (AA) bone marrow in clonogenic assay and long-term bone marrow culture (LTBMC). MGF stimulated colony-forming unit-granulocyte/macrophage (CFU-GM), burst-forming unit-erythroid (BFU-E), and mixed colony-forming unit (consisting of granulocyte-macrophage and erythroid elements) (CFU-GEM) colony formation from both normal and AA marrow. The three-factor combination stimulated the greatest number of colonies. Marrow from less severely affected AA patients was stimulated to produce the highest number of colonies, and a normal response was possible if progenitors were present. When added to LTBMC, MGF alone had little effect. GM-CSF and IL-3 stimulated increased numbers of progenitor cells harvested each week from normal and AA LTBMC. This resulted in normal colony numbers in some patients, the majority of whom were less severely affected than the patients who did not respond in LTBMC. The three-factor combination was additive for normal CFU-GM production. However, no further increases in AA LTBMC resulted from the addition of MGF to GM-CSF and IL-3. The partial correction in clonogenic assay with MGF in some AA patients raises the possibility of therapeutic benefit. We failed to demonstrate increased progenitor cell numbers in AA LTBMC, however. Further studies may overcome possible limitations to progenitor cell proliferation.
Assuntos
Anemia Aplástica/patologia , Células da Medula Óssea , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Interleucina-3/farmacologia , Fator Estimulador de Colônias de Macrófagos/farmacologia , Adolescente , Adulto , Idoso , Contagem de Células , Divisão Celular/efeitos dos fármacos , Divisão Celular/fisiologia , Células Cultivadas , Sinergismo Farmacológico , Feminino , Hematopoese/efeitos dos fármacos , Hematopoese/fisiologia , Células-Tronco Hematopoéticas/citologia , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de TempoRESUMO
BACKGROUND: There are large interindividual differences in CYP3A4 expression and in the metabolism of drug substrates for this enzyme. We and others have identified a polymorphism in the 5' promotor region of the CYP3A4 gene; however, its functional significance is not currently known. This study was conducted to determine whether this polymorphism plays a clinically important role in determining CYP3A4 phenotype. METHODS: An adenine (A) to guanine (G) transition was identified in the 5' promotor region of the CYP3A4 gene at position -292 (from the start codon), in a sequence motif known as the nifedipine-specific element. The frequency of this polymorphism was assessed in 802 healthy volunteers from five broadly defined racial groups. The population distribution of the G allele in these groups was as follows: white Americans (3.6%; n = 273), black Americans (54.6%, n = 186), Hispanic Americans (9.3%; n = 188), Japanese Americans (0.0%; n = 77), and Chinese Americans (0.0%; n = 78). In a subsequent study, 90 additional black Americans were genotyped, and a subset of the homozygous subjects (AA, n = 8; GG, n = 23) were given the CYP3A4 probe substrates erythromycin and nifedipine to allow genotype-phenotype comparisons to be made. RESULTS: There was no difference in the rate of CYP3A4-dependent demethylation of erythromycin (erythromycin breath test) or the pharmacokinetics of nifedipine or its CYP3A4-dependent metabolite dehydronifedipine between the two genotype groups (AA or GG). CONCLUSIONS: This promotor region polymorphism does not appear to play a major role in determining constitutive CYP3A4 expression.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Oxigenases de Função Mista/genética , Polimorfismo Genético , Regiões Promotoras Genéticas/genética , Grupos Raciais/genética , Área Sob a Curva , Povo Asiático/genética , População Negra/genética , Testes Respiratórios , Bloqueadores dos Canais de Cálcio/metabolismo , Citocromo P-450 CYP3A , Primers do DNA , Eritromicina/metabolismo , Genótipo , Hispânico ou Latino/genética , Humanos , Nifedipino/metabolismo , Fenótipo , Inibidores da Síntese de Proteínas/metabolismo , Valores de Referência , População Branca/genéticaRESUMO
Bone marrow and peripheral blood from 28 adult patients with acute myeloid leukemia (AML) were analyzed for the surface expression of the Thy-1 antigen by dual-colour flow cytometry. The Thy-1 antigen was expressed on greater than 5% of cells from seven patients with the proportions of Thy-1 positive cells ranging from 8.1% to 85.0%. The CD34+ Thy-1+ phenotype was present in all seven cases. The expression of Thy-1 on leukemia cells from patients with AML may need to be considered in the development of methods of normal stem cell isolation from these patients.
Assuntos
Crise Blástica , Leucemia Mieloide/imunologia , Leucemia Mieloide/patologia , Antígenos Thy-1/análise , Doença Aguda , Adulto , Idoso , Antígenos CD/análise , Antígenos CD34/análise , Medula Óssea/imunologia , Medula Óssea/patologia , Aberrações Cromossômicas , Feminino , Humanos , Imunofenotipagem , Cariotipagem , Leucemia Mieloide/sangue , Leucemia Mieloide/genética , Masculino , Pessoa de Meia-Idade , Antígenos Thy-1/sangueRESUMO
In an attempt to induce an immune response against tumour antigens, several groups are transfecting cytokine and other genes into autologous tumour cells which are given to the patient as a vaccine. This process is labour-intensive, time-consuming and expensive. Allogeneic cells would offer a more convenient vehicle for the delivery of cytokines and other molecules. However, current dogma suggests that MHC-matched cells are a prerequisite for an effective immune response. Using murine melanoma models we compared allogeneic and autologous vaccination and showed that the survival of C56BL/6 mice (H-2b) was prolonged with some degree of protection achieved against an autologous B15-F10 (H-2b) cell challenge when the mice were vaccinated with allogeneic K1735-M2 (H-2k) cells but not when immunized with autologous B16-F10 cells. Both vaccination with live and irradiated allogeneic cells induced an anti-tumour effect using only one immunization and no boost or adjuvant. Protection was not observed after vaccination with another melanoma (S91; H-2d) or with a carcinoma (A9HT; H-2k). Allogeneic vaccination promoted a cytotoxic cellular response against both the allogeneic and the syngeneic melanomas. This allogeneic vaccination model will be useful for studying the underlying mechanisms of protection, in both pre- and post-challenge settings, as well as for developing whole cell vaccination systems using genetically modified allogeneic tumour cells.
Assuntos
Vacinas Anticâncer/uso terapêutico , Melanoma Experimental/imunologia , Melanoma Experimental/prevenção & controle , Animais , Modelos Animais de Doenças , Feminino , Citometria de Fluxo , Antígenos de Histocompatibilidade Classe I/análise , Antígenos de Histocompatibilidade Classe II/análise , Humanos , Camundongos , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Células Tumorais Cultivadas/efeitos da radiaçãoRESUMO
In a pilot study recombinant human granulocyte colony-stimulating factor (rhG-CSF) was administered to 12 neutropenic preterm infants to determine if neonatal neutropenia is secondary to decreased endogenous G-CSF production. Respiratory variables were monitored because of the possible link between inflammatory cells and hyaline membrane disease. All infants showed increased neutrophil counts. The only possible side effect observed was an exacerbation of thrombocytopenia.
Assuntos
Fator Estimulador de Colônias de Granulócitos/uso terapêutico , Recém-Nascido Prematuro , Neutropenia/terapia , Fator Estimulador de Colônias de Granulócitos/efeitos adversos , Humanos , Lactente , Recém-Nascido , Contagem de Leucócitos , Neutropenia/sangue , Projetos Piloto , Trombocitopenia/etiologiaRESUMO
The incidence of malocclusion was recorded for 4 years. Malocclusion occurred only in animals less than 2 months old. The incidence was significantly reduced (P greater than 0.001) by breeding from animals without affected siblings: it is suggested that malocclusion in this colony has a genetic basis.
Assuntos
Cobaias/genética , Má Oclusão/veterinária , Doenças dos Roedores/genética , Fatores Etários , Animais , Animais Recém-Nascidos , Feminino , Endogamia , Masculino , Má Oclusão/genética , Má Oclusão/patologia , Doenças dos Roedores/patologia , Fatores SexuaisRESUMO
We present a case of virus-associated haemophagocytic syndrome following Epstein-Barr virus infection in which a fulminant pseudomonal supraglottitis developed. Increasingly, unusual pathogens have been found in immunocompromised patients. This is the first reported case of pseudomonal supraglottitis.
Assuntos
Infecções por Herpesviridae/complicações , Histiocitose de Células não Langerhans/complicações , Laringite/microbiologia , Neutropenia/complicações , Infecções Oportunistas/complicações , Infecções por Pseudomonas/complicações , Adolescente , Feminino , Herpesvirus Humano 4 , HumanosRESUMO
Of two groups of 8 college students receiving 15.75 hr. of speed reading training, an experimental group was given an additional 2.25 hr. of peripheral vision training. Peripheral vision increased for both groups, but reading speed improved only in the trained group. Reading comprehension scores were not affected.
Assuntos
Aprendizagem , Leitura , Campos Visuais , Humanos , Prática Psicológica , Fatores de TempoRESUMO
The relationship of habitual use of visual imagery and mental rotation was investigated. Reliance on Visual Imagery scores were used to define subjects as high frequency or low frequency visualizers. During the mental rotation task, subjects indicated if a pair of 2-dimensional stimulus figures displayed on a computer screen were identical or mirror-images. Figures on the right were rotated in relation to those on the left by 0, 60, 120, or 180 degrees. Data supported the prediction that subjects who report high use of imagery would perform the task with greater accuracy (z = 1.97, p < .05) than subjects who reported low use. The imagery groups did not differ in response latency (z = .91, p < .36). A comparison of performance on Trials 1 to 24 with performance on Trials 115-138 indicated a learning effect in both accuracy (z = 7.58, p < .01) and latency (z = 9.72, p < .01) for all subjects.
Assuntos
Imaginação , Percepção Visual , Cognição , Aprendizagem por Discriminação , Feminino , Percepção de Forma , Hábitos , Humanos , Individualidade , Masculino , Modelos Psicológicos , Prática Psicológica , Tempo de Reação , Percepção Espacial , Inquéritos e QuestionáriosRESUMO
AIMS: In order to anticipate drug-interactions of potential clinical significance the ability of the novel antidepressant, venlafaxine, to inhibit CYP2D6 dependent imipramine and desipramine 2-hydroxylation was investigated in human liver microsomes. The data obtained were compared with the selective serotonin re-uptake inhibitors, fluoxetine, sertraline, fluvoxamine and paroxetine. Venlafaxine's potential to inhibit several other major P450 s was also studied (CYP3A4, CYP2D6, CYP1A2). METHODS: Ki values for venlafaxine, paroxetine, fluoxetine, fluvoxamine and sertraline as inhibitors of imipramine and desipramine 2-hydroxylation were determined from Dixon plots of control and inhibited rate data in human hepatic microsomal incubations. The inhibitory effect of imipramine and desipramine on liver microsomal CYP2D6 dependent venlafaxine O-demethylation was determined similarly. Venlafaxine's IC50 values for CYP3A4, CYP1A2 CYP2C9 were determined based on inhibition of probe substrate activities (testosterone 6 beta-hydroxylation, ethoxyresorufin O-dealkylase and tolbutamide 4-hydroxylation, respectively). RESULTS: Fluoxetine, paroxetine, and fluvoxamine were potent inhibitors of imipramine 2-hydroxylase activity (Ki values of 1.6 +/- 0.8, 3.2 +/- 0.8 and 8.0 +/- 4.3 microM, respectively; mean +/- s.d., n = 3), while sertraline was less inhibitory (Ki of 24.7 +/- 8.9 microM). Fluoxetine also markedly inhibited desipramine 2-hydroxylation with a Ki of 1.3 +/- 0.5 microM. Venlafaxine was less potent an inhibitor of imipramine 2-hydroxylation (Ki of 41.0 +/- 9.5 microM) than the SSRIs that were studied. Imipramine and desipramine gave marked inhibition of CYP2D6 dependent venlafaxine O-demethylase activity (Ki values of 3.9 +/- 1.7 and 1.7 +/- 0.9 microM, respectively). Venlafaxine did not inhibit ethoxyresorufin O-dealkylase (CYP1A2), tolbutamide 4-hydroxylase (CYP2C9) or testosterone 6 beta-hydroxylase (CYP3A4) activities at concentrations of up to 1 mM. CONCLUSIONS: It is concluded that venlafaxine has a low potential to inhibit the metabolism of substrates for CYP2D6 such as imipramine and desipramine compared with several of the most widely used SSRIs, as well as the metabolism of substrates for several of the other major human hepatic P450s.
Assuntos
Antidepressivos de Segunda Geração/farmacologia , Antidepressivos Tricíclicos/metabolismo , Hidrocarboneto de Aril Hidroxilases , Cicloexanóis/farmacologia , Desipramina/metabolismo , Imipramina/metabolismo , Microssomos Hepáticos/enzimologia , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Esteroide 16-alfa-Hidroxilase , 1-Naftilamina/análogos & derivados , 1-Naftilamina/farmacocinética , 1-Naftilamina/farmacologia , Antidepressivos de Segunda Geração/farmacocinética , Antidepressivos Tricíclicos/farmacocinética , Cromatografia Líquida de Alta Pressão , Cicloexanóis/farmacocinética , Citocromo P-450 CYP1A2/metabolismo , Inibidores do Citocromo P-450 CYP1A2 , Citocromo P-450 CYP2C9 , Citocromo P-450 CYP2D6/metabolismo , Inibidores do Citocromo P-450 CYP2D6 , Citocromo P-450 CYP3A , Inibidores das Enzimas do Citocromo P-450 , Sistema Enzimático do Citocromo P-450/metabolismo , Desipramina/farmacocinética , Fluoxetina/farmacocinética , Fluoxetina/farmacologia , Fluvoxamina/farmacocinética , Fluvoxamina/farmacologia , Secções Congeladas , Humanos , Hidroxilação , Imipramina/farmacocinética , Técnicas In Vitro , Dose Letal Mediana , Microssomos Hepáticos/efeitos dos fármacos , Oxigenases de Função Mista/antagonistas & inibidores , Oxigenases de Função Mista/metabolismo , Paroxetina/farmacocinética , Paroxetina/farmacologia , Inibidores Seletivos de Recaptação de Serotonina/farmacocinética , Sertralina , Esteroide Hidroxilases/antagonistas & inibidores , Esteroide Hidroxilases/metabolismo , Cloridrato de VenlafaxinaRESUMO
Diamond-Blackfan anemia, although rare, has been the focus of much attention with respect to both its clinical features and the characterization of the in vitro erythroid defect. Despite this, its pathophysiology is still unclear, and the treatment of steroid-refractory patients is still unsatisfactory. The recent chromosomal localization of a gene for familial Diamond-Blackfan anemia represents an important step forward toward the elucidation of this disorder. Therapeutic advances will depend on the development of collaborative studies, employing consensus criteria for diagnosis and response to therapy.
Assuntos
Anemia de Fanconi , Pré-Escolar , Anemia de Fanconi/complicações , Anemia de Fanconi/diagnóstico , Anemia de Fanconi/etiologia , Anemia de Fanconi/fisiopatologia , Anemia de Fanconi/terapia , Humanos , LactenteRESUMO
The metabolism of oestradiol and 17 alpha-ethinyloestradiol to their 2-hydroxy derivatives is an important determinant in their biological effects. In this work, we have investigated which rat or human cytochrome P-450 isoenzymes are involved in catalysing these reactions. Oestradiol 2-hydroxylation was catalysed by a wide variety of rat cytochrome P-450s from gene families P450IA, P450IIB, P450IIC and P450IIIA. Interestingly, 17 alpha-ethinyloestradiol, which only differs structurally from oestradiol at a position distant from the site of oxidation, was metabolized predominantly by members of the P450IIC gene subfamily. In order to establish which enzymes are responsible for the oxidation of these substrates in man, antibodies to rat liver cytochrome P-450 isoenzymes were used to inhibit these reactions in a panel of human liver microsomal fractions. Also, possible correlations between the proteins recognized by the antibodies and the 2-hydroxylation rate were determined. These experiments provide evidence that 2-hydroxylation of 17 alpha-ethinyloestradiol in man is catalysed by cytochromes from the P450IIC, P450IIE and P450IIIA gene families. In contrast, the major proteins involved in oestradiol metabolism are from the P450IA gene family, although members of the P450IIC and P450IIE gene families may also play a role. These data demonstrate that the differences in the capacity of rat P-450s to metabolize these substrates are also present in the comparable enzymes involved in man, and that a variety of factors will determine the rate of disposition of these compounds in man.
Assuntos
Citocromo P-450 CYP1A1 , Sistema Enzimático do Citocromo P-450/metabolismo , Estradiol/metabolismo , Etinilestradiol/metabolismo , Isoenzimas/metabolismo , Fígado/enzimologia , Animais , Anticorpos/farmacologia , Western Blotting , Inibidores das Enzimas do Citocromo P-450 , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/imunologia , Humanos , Hidroxilação , Microssomos Hepáticos/enzimologia , Ratos , Esteroide Hidroxilases/antagonistas & inibidores , Esteroide Hidroxilases/metabolismoRESUMO
The ergot alkaloid CQA 206-291 (CQA) was converted by human liver microsomes (n = 16) almost exclusively to the N-deethylated metabolite (I), as identified by the on-line coupling of liquid chromatography and mass spectroscopy. Metabolite I formation exhibited monophasic and linear enzyme kinetics (2.9-300 microM), and a 5.6-fold interindividual variability (7.2-40.2 nmol/mg/hr). Chemical inhibition experiments revealed that imidazole antimycotic agents (ketoconazole, miconazole, and clotrimazole) were potent inhibitors of this N-deethylation. Polymorphically metabolized substrates (sparteine and phenytoin), well-established cytochrome P-450 probe substrates (antipyrine and tolbutamide), and steroid hormones (estradiol and testosterone) were noninhibitory, indicating that their metabolism is catalyzed by forms of cytochrome P-450 that do not catalyze this route of CQA biotransformation. The ergot alkaloids--dihydroergotamine, bromocriptine, and SDZ 208-911--were competitive inhibitors of metabolite I formation, suggesting that these compounds are metabolized by similar enzymes. Cyclosporine A was a potent competitive inhibitor of CQA metabolism, providing initial evidence that formation of metabolite I was catalyzed by proteins of the CYP3 gene family. This was substantiated by the finding that CQA metabolism was completely inhibited by a polyclonal antibody directed against a pregnenolone 16 alpha-carbonitrile-inducible cytochrome P-450 of rat liver. The rate of CQA metabolism correlated significantly to the level of CYP3A4 expression, the rate of cyclosporine A metabolism to each of the primary metabolites (M-1, M-17, and M-21), and the rate of midazolam 4-hydroxylation. COS 1 cells transfected with human CYP3A4 and CYP3A5 provided direct evidence that these enzymes catalyze the metabolism of CQA.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Dopaminérgicos/metabolismo , Ergolinas/metabolismo , Microssomos Hepáticos/enzimologia , Família Multigênica , Sítios de Ligação de Anticorpos , Ligação Competitiva , Sistema Enzimático do Citocromo P-450/fisiologia , Remoção de Radical Alquila/efeitos dos fármacos , Dopaminérgicos/antagonistas & inibidores , Dopaminérgicos/química , Ergolinas/antagonistas & inibidores , Ergolinas/química , Humanos , Cinética , Microssomos Hepáticos/efeitos dos fármacos , Microssomos Hepáticos/metabolismoRESUMO
The U.K. Diamond-Blackfan Anaemia (DBA) Registry was established with the aim of providing a representative database for studies on the aetiology, pathophysiology and treatment of DBA. We have analysed retrospective data from 80 cases (33 male, 47 female) born in the U.K. in a 20-year period (1975-94), representing an annual incidence of 5 per million live births. Ten children from seven families had an apparently familial disorder. 13% were anaemic at birth, and 72.5% had presented by the age of 3 months. 67% had macrocytosis at presentation. 72% responded initially to steroids, and at the time of study 61% were transfusion-independent (45% steroid-dependent) and 39% required regular transfusions. Unequivocal physical anomalies, predominantly craniofacial, were present in 37%, and were more likely in boys (52%) than girls (25%). 18% had thumb abnormalities. Height was below the third centile for age in 28%, and 31% had neither short stature nor physical anomalies. Four children without physical abnormalities had normal red cell indices, and achieved steroid-independent remission, suggesting transient erythroblastopenia of childhood rather than DBA. The birth month distribution of children with sporadic DBA and craniofacial dysmorphism showed a possible seasonality, consistent with a viral aetiology.
Assuntos
Anemia de Fanconi/genética , Idade de Início , Estudos de Coortes , Anemia de Fanconi/sangue , Anemia de Fanconi/epidemiologia , Feminino , Transtornos do Crescimento/complicações , Humanos , Incidência , Masculino , Remissão Espontânea , Estudos Retrospectivos , Estações do Ano , Fatores Sexuais , Esteroides/uso terapêutico , Reino Unido/epidemiologiaRESUMO
We investigated the frequencies of early populations of progenitors in aplastic anaemia (AA) bone marrow, from patients with a range of disease severity, compared with normal. Double-colour immunofluorescent staining for CD34 and CD33 was carried out on bone marrow mononuclear cells (BMMC) and analysed using fluorescence activated cell sorting (FACS). AA CD34+ cells were reduced by 68% compared to normal. In addition, AA CD33+ cells and the three progenitor subsets (CD34+/CD33-, CD34+/CD33+ and CD34-/CD33+) were reduced by 44-80%. Our data lend further support for an early stem cell deficiency in AA.
Assuntos
Anemia Aplástica/patologia , Medula Óssea/patologia , Células-Tronco Hematopoéticas/patologia , Adolescente , Adulto , Antígenos CD/análise , Antígenos CD34 , Antígenos de Diferenciação Mielomonocítica/análise , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Lectina 3 Semelhante a Ig de Ligação ao Ácido SiálicoRESUMO
Culture of bone marrow from patients with Diamond-Blackfan anaemia (DBA) has previously shown a variable progenitor response to growth factor stimulation. An extensive standardized study has now been undertaken to investigate the presence of distinct sub-groups in this disorder. In vitro response of bone marrow progenitors to recombinant human growth factors, including stem cell factor, was examined in 18 DBA patients and five normal donors, assessing BFU-E, CFU-GM and CFU-GEMM development. In 16 of the DBA patients a synergistic response to combinations of growth factors was observed with optimal growth in cultures containing erythropoietin, interleukin-3 and stem cell factor. Growth factor induced erythroid response formed three distinct groups, based on BFU-E numbers: type I (mean age 4.87 years) showed > 70% normal erythroid response; type II (mean age 13.87 years) showed < 70% normal; and type III (mean age 15.29 years) < 5% normal. CFU-GM response also followed the trigrouping. The results suggest more than one pathogenic mechanism for the erythroid failure in DBA, indicating DBA may be composed of more than one distinct disorder, and further suggest the defect in DBA may not be confined to the erythroid series.
Assuntos
Eritropoese/fisiologia , Anemia de Fanconi/fisiopatologia , Fatores de Crescimento de Células Hematopoéticas/farmacologia , Adolescente , Adulto , Medula Óssea/patologia , Células Cultivadas , Criança , Pré-Escolar , Ensaio de Unidades Formadoras de Colônias , Células Precursoras Eritroides/patologia , Eritropoetina/farmacologia , Anemia de Fanconi/patologia , Feminino , Células-Tronco Hematopoéticas/patologia , Humanos , Lactente , Interleucina-3/farmacologia , Masculino , Pessoa de Meia-Idade , Proteínas Recombinantes/farmacologia , Fator de Células-TroncoRESUMO
In vitro models are being used increasingly during all phases of the drug development process in concert with the more traditional in vivo toxicological and pharmacokinetic evaluations. These in vitro models may be classified empirically as either validated in vitro screens, value-added screens or 'ad-hoc' mechanistic screens. The application of these screens is discussed with respect to their level of validation, standardization, uses of human tissue, level of iteration with in vivo studies, regulatory position and utility in the drug discovery and development process. The predictability and reproducibility of these screens is discussed, as well as future trends in regard to emerging technology and its application.
Assuntos
Avaliação Pré-Clínica de Medicamentos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Preparações Farmacêuticas/metabolismo , Testes de Toxicidade , Animais , Humanos , Técnicas In Vitro , Modelos Biológicos , Reprodutibilidade dos Testes , Testes de Toxicidade/métodos , Testes de Toxicidade/normas , Testes de Toxicidade/tendênciasRESUMO
Interleukin-3 (IL-3) therapy as a treatment for Diamond Blackfan anaemia (DBA) patients has been largely disappointing despite early hope it would be suitable for stimulating arrested erythropoiesis. Initial hope came from in vitro discoveries that IL-3 (+EPO) generated well-haemoglobinized BFU-E colonies in some patients, but was soon tempered by the realization that in vitro and in vivo IL-3 response did not, in the majority of cases, correlate. Nevertheless in vitro testing has been the main focus in analysing the abnormality in the stem and progenitor cell compartment in DBA. Here we report in vitro analysis of a DBA patient who responded once to IL-3 therapy, but not a second time following relapse, using short-term culture, long-term culture and c-kit analysis. Progenitor numbers before and after the first therapy were in the high normal range, but after relapse were much reduced below normal levels. Long-term cultures suggested some arrested progenitors had been reactivated into normal cycle by the first therapy, but may not have been replaced by more immature progenitors. c-kit analysis revealed increased expression in all tested cell populations. These results imply that the first IL-3 therapy reactivated some erythroid progenitors but left the progenitor pool depleted when more immature cells remained arrested.