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1.
J Med Ethics ; 32(5): 273-7, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16648277

RESUMO

BACKGROUND: Although maternal serum screening (MSS) for Down's syndrome has become routinely available in most obstetric clinics in many countries, few studies have addressed the reasons why women agree to undergo the MSS test. OBJECTIVES: The aims of this study were to describe the circumstances in which MSS was offered to pregnant women and their reasons for undertaking it. METHODS: Participant observation and in depth interviews were used in this study; specifically, the experiences of women who had a positive result for MSS and who then followed this up with amniocentesis were examined. The interviewees were twenty six mothers aged between 22 and 35 years. The interviews were audio taped and transcribed for analysis. The results were analysed by the constant comparative method. RESULTS: This study identified the reasons on which pregnant women appeared to base their decisions when undergoing MSS. The reasons were first, the recognition that the procedure was a prenatal routine procedure; second, the need to avoid the risk of giving birth to a baby with Down's syndrome, and third, a trust in modern technology and in the professional authorities. CONCLUSIONS: This study offers insights into the informed choice made by women with a positive MSS result. The reasons for undergoing MSS might help health professionals and policy makers to reflect on their practice and this may, in turn, improve the quality of prenatal care during MSS.


Assuntos
Síndrome de Down/diagnóstico , Doenças Fetais/diagnóstico , Programas de Rastreamento/psicologia , Diagnóstico Pré-Natal/métodos , Adulto , Amniocentese/psicologia , Atitude Frente a Saúde , Comportamento de Escolha , Técnicas de Laboratório Clínico , Tomada de Decisões , Síndrome de Down/sangue , Feminino , Humanos , Consentimento Livre e Esclarecido/psicologia , Aceitação pelo Paciente de Cuidados de Saúde/psicologia , Gravidez , Fatores de Risco , Confiança/psicologia
3.
Acta Paediatr Taiwan ; 42(5): 311-3, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11729711

RESUMO

Myocarditis complicated with complete heart block is rare in childhood. We report a case of 4-year-old child presented with complete heart block which may have been caused by Mycoplasma pneumoniae. Under emergent temporal pacing, patient experienced cardiogenic shock with pulmonary edema eventually. The cardiopulmonary function was improved with atrial rhythm at the 6th hour later after intravenous infusion with high-dose gamma-globulin (IVIG). The IVIG therapy may have immunomodulatory effects and serve as a potential adjunctive therapy for fulminant myocarditis.


Assuntos
Bloqueio Cardíaco/microbiologia , Imunoglobulinas Intravenosas/uso terapêutico , Miocardite/complicações , Miocardite/tratamento farmacológico , Pneumonia por Mycoplasma/complicações , Estimulação Cardíaca Artificial , Pré-Escolar , Eletrocardiografia , Serviço Hospitalar de Emergência , Bloqueio Cardíaco/diagnóstico por imagem , Bloqueio Cardíaco/fisiopatologia , Humanos , Masculino , Miocardite/microbiologia , Miocardite/patologia , Ultrassonografia
4.
Neuroradiology ; 43(8): 653-61, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11548174

RESUMO

With limited near-field resolution and accessible acoustic windows, sonography has not been advocated for assessing central nervous system injuries in the shaken-baby syndrome. Our purpose was to correlate high-resolution ultrasonographic characteristics of central nervous system injuries in whiplash injuries and the shaken-baby-syndrome with MRI and CT. Ultrasonographic images of 13 infants, aged 2-12 months, with whiplash or shaking cranial trauma were reviewed and compared with MRI in 10 and CT in 10. Five patients had serial ultrasonography and MRI or CT follow-up from 1 to 4 months after the initial injury. With ultrasonography we identified 20 subdural haematomas. MRI and CT in 15 of these showed that four were hyperechoic in the acute stage, three were mildly echogenic in the subacute stage, and that one subacute and seven chronic lesions were echo-free. Five patients had acute focal or diffuse echogenic cortical oedema which evolved into subacute subcortical hyperechoic haemorrhage in four, and well-defined chronic sonolucent cystic or noncystic encephalomalacia was seen at follow-up in two. Using ultrasonography we were unable to detect two posterior cranial fossa subdural haematomas or subarachnoid haemorrhage in the basal cisterns in three cases, but did show blood in the interhemispheric cistern and convexity sulci in two. U1-trasonography has limitations in demonstrating abnormalities remote from the high cerebral convexities but may be a useful adjunct to CT and MRI in monitoring the progression of central nervous system injuries in infants receiving intensive care.


Assuntos
Síndrome da Criança Espancada/diagnóstico por imagem , Ecoencefalografia , Feminino , Seguimentos , Humanos , Lactente , Masculino
5.
J Pediatr ; 139(3): 433-7, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11562625

RESUMO

This study was conducted to investigate whether a single dose of nebulized budesonide effectively decreased airway inflammation as demonstrated by exhaled nitric oxide (eNO) levels. A single dose of nebulized budesonide, but not nebulized terbutaline, rapidly decreased eNO levels in 6 hours. The decrease in eNO levels induced by nebulized budesonide was correlated to an increase in peak expiratory flow rate.


Assuntos
Asma/tratamento farmacológico , Broncodilatadores/uso terapêutico , Budesonida/uso terapêutico , Óxido Nítrico/metabolismo , Terbutalina/farmacologia , Adolescente , Pressão Sanguínea/efeitos dos fármacos , Broncodilatadores/administração & dosagem , Budesonida/administração & dosagem , Estudos de Casos e Controles , Criança , Feminino , Humanos , Masculino , Nebulizadores e Vaporizadores , Pico do Fluxo Expiratório/efeitos dos fármacos , Terbutalina/administração & dosagem
6.
J Microbiol Immunol Infect ; 34(4): 297-300, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11825012

RESUMO

Cytomegalovirus causes pneumonia, hepatitis, thrombocytopenia, and hemolytic anemia. Cytomegalovirus adrenalitis in premature infants, however, is rare. This report described a premature newborn who had progressively worsening hyperbilirubinemia, pancytopenia, and hepatosplenomegaly at the age of 4 days. The baby's mother had prolonged rupture of amniotic membrane for about 8 weeks. The infant received exchange blood transfusion, empiric antibiotics treatment, and mechanical ventilation. Pneumonia and sepsis developed at the age of 18 days. Serum anticytomegalovirus immunoglobulin M and urine virus culture were positive for cytomegalovirus. The baby died at the age of 22 days. Autopsy showed cytomegalovirus infection complicated with interstitial pneumonitis and pulmonary edema, subacute bronchopulmonary dysplasia with interstitial fibrosis, and adrenalitis. We concluded that the functional status of the adrenal glands in cytomegalovirus-infected premature newborns who have unexplained electrolytes imbalance, fever, diarrhea, weight loss, or hypotension should be closely followed because of the possible involvement of adrenal glands.


Assuntos
Doenças das Glândulas Suprarrenais/microbiologia , Infecções por Citomegalovirus/congênito , Doenças das Glândulas Suprarrenais/congênito , Doenças das Glândulas Suprarrenais/patologia , Evolução Fatal , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Inflamação/microbiologia , Pneumonia/complicações , Pneumonia/microbiologia
7.
Acta Paediatr Taiwan ; 41(4): 214-7, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11021008

RESUMO

Subglottic hemangioma (SGH) is a benign neoplasm that may cause severe and life-threatening respiratory obstruction in infants. However, patients usually present with inspiratory stridor in the first few months of life and may be mistakenly diagnosed as recurrent or persistent croup. Definitive diagnosis is made by image studies, endoscopic examination and biopsy or all. We report a 2-month-old female infant of SGH with initial clinical manifestations of dyspnea and inspiratory stridor co-existing with cutaneous and cerebellar hemangiomas. Clinicians must be alert the possibility of SGH when associated with cutaneous hemangioma. This patient has received oral steroid treatment for more than two months with improvement of the airway obstruction. Although purplish patch lesions over left side of face, eyelid, cheek, and peri-oral regions regressed, the size of the SGH on the followed MRI was slightly enlarged. The diagnosis and various treatments of SGH are discussed and reviewed in this paper.


Assuntos
Neoplasias Cerebelares/diagnóstico , Hemangioma/diagnóstico , Neoplasias Cutâneas/diagnóstico , Neoplasias da Língua/diagnóstico , Corticosteroides/uso terapêutico , Neoplasias Cerebelares/terapia , Feminino , Hemangioma/terapia , Humanos , Lactente , Imageamento por Ressonância Magnética , Neoplasias Cutâneas/terapia , Neoplasias da Língua/terapia
8.
Acta Paediatr Taiwan ; 41(3): 147-50, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10920548

RESUMO

Neonates with cerebral infarction do not present with specific symptoms and the condition is usually insidious, so many atypical cases are not diagnosed properly during the neonatal stage. Normal neurological examination results may be found in newborns who have actually had a cerebral infarction insidiously. We present two newborns with cerebral infarction. One had clinical symptoms of seizures. Brain computed tomography showed a low-attenuated area and magnetic resonance angiography showed a decreased caliber and number of cerebral artery branches. The other had normal neurological examination results. He was referred to our hospital due to cyanosis. Brain sonography revealed a focal hyperechoic area and T2 weighted magnetic resonance image showed an increased signal intensity area. The incidence, etiologies, clinical and radiographic findings are also reviewed.


Assuntos
Infarto Cerebral/diagnóstico , Doenças do Prematuro/diagnóstico , Encéfalo/patologia , Infarto Cerebral/etiologia , Diagnóstico Diferencial , Humanos , Recém-Nascido , Doenças do Prematuro/etiologia , Angiografia por Ressonância Magnética , Masculino , Exame Neurológico , Tomografia Computadorizada por Raios X
9.
Acta Paediatr Taiwan ; 41(3): 158-60, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10920551

RESUMO

Xanthoma invasion of the bone is a very rare disease especially in normolipidemic children. Bone erosion can be found in patients with this disease. However, due to the similarity of the symptoms of xanthoma with many other diseases including malignancy, the other diseases may initially be to be suggested and xanthoma may not even be considered. In this paper, we present an 8-year-old normolipidemic male child with a parietal bone xanthoma proved using tissue diagnosis. The clinical, radiographic and histological findings are also reviewed.


Assuntos
Lipídeos/sangue , Osso Parietal/diagnóstico por imagem , Xantomatose/diagnóstico por imagem , Criança , Humanos , Masculino , Osso Parietal/patologia , Radiografia , Valores de Referência , Xantomatose/patologia
10.
Pediatr Neurol ; 22(3): 214-9, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10734252

RESUMO

Bilateral fisting of hands, including adduction and infolding of the thumbs (cortical thumbs), is an expected finding in term infants. Clinically, the cortical thumb position is a transient and normal, but not general, hand posture in newborns. The aim of this study was to analyze the rate of occurrence and the factors possibly affecting the cortical thumb (thumb-in-palm) posture in term newborns. We enrolled 197 low-risk term newborns and observed the posture of their hands once daily from the day of birth for 3 consecutive days. The occurrence rates of the thumb-in-palm posture of the right hand on the first, second, and third days were 62.8%, 60.9%, and 50%, respectively, and those of the left hand were 60.3%, 55.8% and 53.2%, respectively. There was a significant reduction on a day-to-day basis in the right hand and an insignificant reduction in that of the left hand. Factors including sex, gestation age, birth weight, method of delivery, and alertness were analyzed, and no relationship was evident between these factors and the occurrence rates of the cortical thumb posture. Our observations suggest that the cortical thumb posture is indeed a predominant hand posture in our hospital, yet it is not a general phenomenon in all term newborns.


Assuntos
Desenvolvimento Infantil/fisiologia , Parto Obstétrico/métodos , Polegar , Fatores Etários , Índice de Apgar , Peso ao Nascer , Feminino , Lateralidade Funcional , Idade Gestacional , Humanos , Recém-Nascido , Masculino , Razão de Chances , Postura/fisiologia , Valores de Referência , Estudos de Amostragem
11.
Eur J Pediatr ; 158(2): 144-6, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10048612

RESUMO

UNLABELLED: The effectiveness of single and multiple applications of triple dye for umbilical cord care in the umbilical cord separation time (UCST) was evaluated in 180 neonates. Seven neonates were excluded, three where the cord stump separation time was uncertain and four to whom contact was lost. The participating neonates were randomly assigned to two groups. Group 1, 101 neonates, were treated with a regimen of a single application of triple dye. Group 2, 79 neonates, were treated with multiple applications of triple dye. Complete information was obtained from 97 neonates (96.2%) in group 1 and 76 (96%) in group 2. The UCST was 12.6 +/- 0.45 (mean +/- SE) days in group 1 and 16.68 +/- 0.65 days in group 2 (P < 0.0001) and showed no significant association with infants' gender, mode of delivery, gravidity, gestational age, birth weight, or hospital stay. CONCLUSION: A single application of triple dye may be a more favourable regimen with a similarly antimicrobial effect, a shorter UCST and may be more cost effective than multiple applications of triple dye in umbilical cord care.


Assuntos
Anti-Infecciosos/administração & dosagem , Violeta Genciana/administração & dosagem , Proflavina/administração & dosagem , Compostos de Amônio Quaternário/administração & dosagem , Cordão Umbilical/efeitos dos fármacos , Distribuição de Qui-Quadrado , Combinação de Medicamentos , Feminino , Humanos , Recém-Nascido , Masculino , Estudos Prospectivos , Fatores de Tempo , Cordão Umbilical/microbiologia
12.
AJNR Am J Neuroradiol ; 19(9): 1628-30, 1998 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9802482

RESUMO

Late infantile GM1 gangliosidosis is an extremely rare metabolic disorder with clinical features of seizure and progressive motor and mental retardation without facial dysmorphism or visceral organomegaly. We report the CT and MR imaging findings in one infant, which included abnormalities of the cerebral cortex, white matter, and deep nuclei.


Assuntos
Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Gangliosidose GM1/diagnóstico , Imageamento por Ressonância Magnética , Tomografia Computadorizada por Raios X , Feminino , Humanos , Lactente
13.
J Pharm Biomed Anal ; 16(6): 1059-66, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9547710

RESUMO

In this study, a high pressure liquid chromatography method with fluorescent detector was developed to analyze blood galactose, lactose and glucose simultaneously. Plasma sugars were prepared as fluorescent derivatives to react with FMOC-hydrazine (9-fluorenyl methyl chloroformate). A C18 reversed phase column and a fluorescent detector were used and run in ambient. The resolution index of galactose and glucose derivatives in the analytical method was 1.15. The coefficients of variation of the analysis were less than 7.5%. The concentration of FMOC-hydrazine did not significantly influence the analytical results for determination of the concentration of galactose. However, the ratios of acetonitrile in the mobile phase significantly affected the analysis of the fluorescent derivatives of sugars. The sensitivity of this method for galactose detection was 5 micrograms ml-1, and the required plasma volume for testing was only 25 microliters each. This analytical method was successfully applied to study the pharmacokinetics of galactose in vivo in a rabbit model.


Assuntos
Glicemia/análise , Animais , Calibragem , Cromatografia Líquida de Alta Pressão , Feminino , Fluorenos , Corantes Fluorescentes , Galactosemias/metabolismo , Hidrazinas , Lactose/sangue , Masculino , Coelhos , Padrões de Referência , Reprodutibilidade dos Testes , Espectrometria de Fluorescência
14.
AJNR Am J Neuroradiol ; 19(3): 550-2, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9541317

RESUMO

We report two infants with Werdnig-Hoffmann disease diagnosed by means of spinal MR imaging, histopathologic examination of muscle biopsy specimens, cloned DNA analysis, electrophysiological examination, and clinical history. The MR findings were consistent with previous histopathologic reports.


Assuntos
Imageamento por Ressonância Magnética , Atrofias Musculares Espinais da Infância/diagnóstico , Atrofia , Eletromiografia , Eletrofisiologia , Feminino , Deleção de Genes , Humanos , Lactente , Masculino , Fibras Musculares Esqueléticas/patologia , Músculo Esquelético/patologia , Atrofias Musculares Espinais da Infância/genética , Atrofias Musculares Espinais da Infância/fisiopatologia
15.
J Parasitol ; 83(3): 551-3, 1997 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-9194850

RESUMO

Chromosome number of an axenically grown Trichomonas vaginalis isolate was studied using a 1 mM solution of colchicine and a hypotonic swelling technique. The diploid chromosome number was 2n = 6 [corrected]. Each pair of chromosomes can be identified by its morphology and size. This observation could be important with respect to gene mapping and molecular cloning for genes of T. vaginalis.


Assuntos
Cromossomos , Trichomonas vaginalis/genética , Animais , Cromossomos/ultraestrutura , Colchicina , Meios de Cultura , Diploide , Cariotipagem , Metáfase , Trichomonas vaginalis/crescimento & desenvolvimento , Trichomonas vaginalis/ultraestrutura
16.
J Med Virol ; 46(3): 216-23, 1995 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7561793

RESUMO

Human monocyte-derived cytotoxic factors (CF) induced by dengue virus were studied. Using several human leukemia cell lines as precursors, the biological activities of CF in conditioned medium from dengue virus-infected monocytes were demonstrated through the measurement of tumor cell growth inhibition. The conditioned medium from dengue virus infected monocytes suppressed significantly growth of CEM, HL60, K562, and U937 cells. In the presence of 10% conditioned medium (v/v) from dengue virus infected monocytes, DNA synthesis of U937 cells, as measured by [3H]thymidine incorporation, decreased by 99% in contrast to their synthesis in conditioned medium from noninfected control monocytes, which did not have any suppressive effect. Partial characterization of CF showed that it is a proteinase-K-sensitive and heat-labile protein with a molecular mass over 100 kDa. Employing a flow cytometric analysis of the cell cycle, it was found that U937 cells, treated either with conditioned medium from dengue virus infected monocytes or with CF, but not treated with conditioned medium from noninfected monocytes, showed cell-cycle arrest in G1 phase by 48 hr. This suppressive effect of CF on U937 growth was dose- and time-dependent. These results suggest that dengue virus-infected monocytes may produce CF to target myeloid cells, resulting in the hematological changes observed in patients with dengue fever.


Assuntos
Citocinas/metabolismo , Vírus da Dengue/imunologia , Leucócitos Mononucleares/virologia , Adulto , Animais , Ciclo Celular , Divisão Celular , Linhagem Celular , Meios de Cultivo Condicionados , Testes Imunológicos de Citotoxicidade , Humanos , Leucócitos Mononucleares/imunologia , Células Tumorais Cultivadas
17.
Artigo em Chinês | MEDLINE | ID: mdl-8333287

RESUMO

The Lowe syndrome, or oculocerebrorenal syndrome, is a rare X-linked recessive hereditary disease which typically involves three major systems including ocular defects (congenital cataracts, glaucoma, searching nystagmus), central nervous system defects (generalized hypotonia with decreased or absent deep tendon reflex and severe mental retardation), and renal dysfunction (progressive renal tubular dysfunction with acidosis and hyperaminoaciduria). Less than 200 cases have been reported in the English literatures since 1952. This article presents the first case of Lowe syndrome in Taiwan. Patient was a newborn who was born with congenital cataracts, glaucoma, generalized hypotonia with areflexia. In following laboratory studies showed early manifestations of renal tubular dysfunction with metabolic acidosis, proteinuria, glycosuria, phosphaturia and generalized hyperaminoaciduria (19 types). CT of brain showed an arachnoid cyst about 4.5 x 5 cm in size below the cerebellar tentorium. Large amount of copper, about 20-30 times above normal range, was detected in the urine. To our knowledge, Lowe syndrome associated with hypercupriuria and arachnoid cyst has not been reported in the past. Whether hypercupriuria is a part of the entity of this disease or prodromal stage of Wilson's disease is obscure. Further investigation and long-term observation are necessary to draw any conclusion.


Assuntos
Síndrome Oculocerebrorrenal/diagnóstico , Cistos Aracnóideos/complicações , Cobre/urina , Humanos , Recém-Nascido , Masculino , Síndrome Oculocerebrorrenal/complicações , Síndrome Oculocerebrorrenal/genética , Diagnóstico Pré-Natal
18.
J Formos Med Assoc ; 91(12): 1162-5, 1992 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1363637

RESUMO

The major concern of the national population policy in Taiwan in recent years has been to lower the incidence of hereditary diseases and mental retardation in the general population. It has been estimated that there are around 10,000 mentally retarded school children in Taiwan. If effective chromosomal screening can be extended to these children, some of the family members who are carriers of balanced chromosomal rearrangements may benefit from follow-up studies and genetic counseling. The present report is the result of a pilot study conducted from 1988 to 1991 to explore the possibility of chromosomal screening of mentally retarded school children in Taipei. A total of 871 blood samples were collected from 1,147 children registered in 46 schools or residing in homes for the retarded. Chromosomal analysis was successfully accomplished on 674 out of 871 blood samples. The following chromosomal abnormalities were observed: 28 Down's syndrome, four Klinefelter syndrome, one XYY, one triple X, 11 translocations, seven inversions, four mosaics, three duplications, one deletion and one with an extra marker chromosome. After follow-up cytogenetic analyses of 13 families with probands with structural chromosomal anomalies, three of these families were shown to have one or two carriers of balanced translocated chromosomes. It seems that the present screening system would not be practical or cost-effective if it were applied island-wide in the future.


Assuntos
Aberrações Cromossômicas , Deficiência Intelectual/genética , Adolescente , Criança , Feminino , Seguimentos , Aconselhamento Genético , Humanos , Masculino , Aberrações dos Cromossomos Sexuais/genética
19.
J Biol Chem ; 264(18): 10904-10, 1989 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-2659598

RESUMO

Glucocorticoids induce growth inhibition and eventually cause cell lysis in certain sensitive leukemic cells. To investigate how glucocorticoids interact with cell growth pathways, we studied the expression of 14 growth-related genes in dexamethasone-treated CEM-C7A cells, a steroid-sensitive clone of the CCRF-CEM cell line, and in several closely related clones. The 14 genes studied were chosen to represent four different levels of mitogenic signal transduction. Detectable mRNA levels were found for 8 of the 14 genes, but among these only c-myc expression was obviously suppressed by dexamethasone. The c-myc mRNA levels declined abruptly during the first 12 h after addition of 1 microM dexamethasone, and maximal suppression occurred by 18 h. This change was not seen in the C7A controls, in the glucocorticoid-resistant, receptor-deficient clone ICR-27, or in the glucocorticoid-resistant, receptor-positive clone C1. H.10, a hybrid clone between C1 and ICR-27, showed restoration of the sensitive phenotype, and in H.10 cells the c-myc mRNA was also suppressed by dexamethasone. Our results suggest that: 1) functional glucocorticoid receptor is required for inducing c-myc suppression. 2) In dexamethasone-resistant cells with functional receptors c-myc is not suppressed. 3) The growth arrest induced by glucocorticoids correlates with, and may be regulated via, suppression of c-myc expression.


Assuntos
Dexametasona/farmacologia , Proteínas Proto-Oncogênicas/genética , Proto-Oncogenes/efeitos dos fármacos , RNA Mensageiro/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacos , Northern Blotting , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Cinética , Leucemia-Linfoma de Células T do Adulto/genética , Hibridização de Ácido Nucleico , Proteínas Proto-Oncogênicas c-myc
20.
J Steroid Biochem ; 30(1-6): 63-70, 1988.
Artigo em Inglês | MEDLINE | ID: mdl-3164435

RESUMO

In the cultured acute lymphoblastic leukemic (ALL) cell line, clones of sensitive cells are killed by receptor-occupying concentrations of glucocorticoids. In addition, several types of resistance have been identified. The types of resistance are r- (glucocorticoid binding site loss), ract/l (activation labile receptors) and r+ly- (defective lysis mechanism). The two types of receptor mutants have been examined for the presence and expression of the glucocorticoid receptor (GR) gene. Southern blot analysis, using a full-length cDNA probe for human GR, shows that the gene in both is grossly intact. Examination of the expression of the gene by Northern blots reveals the presence of normal, 7-kb message in both types of receptor mutants, though in amounts somewhat reduced from wild-type. This report focuses on the activation labile mutants. Since characterization of these mutants suggests that they can bind ligand but not retain it during activation, we hypothesized that they would respond normally to a ligand that could not be lost during activation. This seems to be the case. When the covalent affinity ligand dexamethasone mesylate, itself a partial glucocorticoid agonist/antagonist, is used, the ract/l cells are killed to an extent corresponding to that evoked by a sub-optimal concentration of the full agonist dexamethasone. We conclude: (1) that the ract/l receptors can function to kill cells if provided a ligand that they do not lose during activation; (2) that the partial agonist activity of dexamethasone mesylate for cell killing is not due to release of a small amount of free dexamethasone; (3) that the poor agonist activity of dexamethasone mesylate receptor complexes suggests that the role of steroid is strictly to participate in conversion of the receptor to its DNA binding form, after which presence of the steroid actually interferes with proper receptor action.


Assuntos
Dexametasona/análogos & derivados , Genes , Mutação , Receptores de Glucocorticoides/genética , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Dexametasona/farmacologia , Humanos , Cinética , Leucemia Linfoide , Receptores de Glucocorticoides/efeitos dos fármacos , Receptores de Glucocorticoides/isolamento & purificação
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