RESUMO
BACKGROUND AND OBJECTIVES: Written and verbal communication skills are important skills for all physicians. While verbal skills are taught and assessed in medical school, medical students report limited instruction in written communication skills. This study examined the impact of a curriculum delivered during a 6-week clinical rotation in Internal Medicine on the objective assessment of medical students' written communication skills. METHODS: The curriculum consisted of two educational programmes: a medical student communication tutorial and a resident feedback workshop. The study was conducted from March 2012 to January 2013 at McMaster University in Hamilton, Ontario, Canada. The study featured three arms: (1) control, (2) medical student communication tutorial alone and (3) student tutorial and resident feedback workshop. Data were collected on 126 students during 6-week Internal Medicine clerkship rotations. Students' written consultation notes were collected prior to the educational programmes and at 6â weeks. Blinded faculty assessors used an independently validated Assessment Checklist to evaluate consultation notes. RESULTS: Consultation note scores improved from week 1 to week 6 across all study arms. However, the change was statistically significant only in arm 3, featuring both the medical student tutorial and the resident feedback workshop, with mean scores improving from 4.75 (SD=1.496) to 5.56 (SD=0.984) out of 7. The mean difference between week 1 and week 6 was significantly different (0.806, p=0.002, 95% CI 0.306 to 1.058). CONCLUSIONS: The combination of a resident feedback workshop with medical student written communication tutorial improves objective evaluations of consultation note scores over student tutorial alone.
Assuntos
Estágio Clínico/normas , Competência Clínica/normas , Currículo , Educação de Graduação em Medicina , Estudantes de Medicina , Redação , Adulto , Canadá/epidemiologia , Comunicação , Educação de Graduação em Medicina/organização & administração , Feminino , Humanos , Masculino , Desenvolvimento de Programas , Avaliação de Programas e Projetos de Saúde , Estudos Prospectivos , Redação/normasRESUMO
The elongated alpha-globin chains of hemoglobin Constant Spring (alpha cs chain of HbCS ) are produced in low amounts such that the alpha cs-gene acts as a form of alpha-thalassemia; yet in the homozygous state the pathophysiological effects of this mutant are more severe than in the corresponding conditions that result from alpha-globin gene deletions. In studies designed to examine this discrepancy, we have demonstrated that a significant proportion of red cells produced in an HbCS homozygote has a much reduced red cell life span. Contrary to previous reports, we have been able to demonstrate the expected deficit in alpha-chain production in this condition and have shown that both the cessation of globin chain synthesis in vitro and the destruction of the excess beta-chains occur unusually rapidly. Comparison with various deletion forms of alpha-thalassemia suggests that, in terms of intracellular globin chain precipitates and free beta-chain pool, homozygous HbCS red cells more closely resemble those of HbH disease, with three of the four alpha-genes inactivated, than they do the more comparable alpha-thalassemia carriers with only two genes deleted.
Assuntos
Eritrócitos/fisiologia , Hemoglobinas Anormais/metabolismo , Homozigoto , Adulto , Medula Óssea/ultraestrutura , Sobrevivência Celular , Envelhecimento Eritrocítico , Globinas/genética , Hemoglobinas/análise , Humanos , Cinética , Masculino , Microscopia Eletrônica , Talassemia/sangueRESUMO
6 out of 14 uncharacterized beta-thalassemia alleles from 187 Thai beta-thalassemia/HbE patients were identified by direct sequencing of DNA amplified by polymerase chain reaction. A novel mutation occurring from an insertion of adenosine in codon 95, which results in a shift of the reading frame with terminator at the new codon 101, was detected in one patient. In addition, two frameshift mutations not previously reported among the Thai population were also detected in 3 patients: one with a deletion of thymidine in codon 15 and two with an insertion of cytidine in codons 27/28. A frameshift mutation that occurred from a cytidine deletion in codon 41 was also found in one patient in this study. The remaining case was an amber mutation, GAG-TAG, in codon 43 in exon 2 of the beta-globin gene. These mutations bring the number of mutations known to be present in the Thai population to a total of 20, 15 of which were detected in beta-thalassemia/HbE patients.
Assuntos
Mutação da Fase de Leitura , Globinas/genética , Hemoglobina E/genética , Mutação , Talassemia/genética , Adulto , Alelos , Sequência de Bases , Feminino , Heterozigoto , Humanos , Lactente , Masculino , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , TailândiaRESUMO
Twelve patients with beta-thalassemia/hemoglobin E disease had spinal cord compression. Ten were made and two female, aged 17 to 40 years. The causes of spinal cord compression presumably were extramedullary hematopoietic masses. This was proved by surgery in two cases. In six cases, myelography demonstrated extradural blockade. In the others, the recurrent nature of the paraparesis and the prompt response to deep x-ray therapy were compatible with cord compression by extramedullary hematopoietic masses. Although spontaneous recovery and disappearance of the neurological signs after blood transfusions were observed, these were slow and uncertain. Deep x-ray therapy led to prompt response with more lasting benefit in all cases and is thus recommended as standard treatment for this complication.
Assuntos
Compressão da Medula Espinal/etiologia , Talassemia/complicações , Adolescente , Adulto , Feminino , Hemoglobina E , Hemoglobinúria/radioterapia , Humanos , Masculino , Compressão da Medula Espinal/radioterapia , Talassemia/sangue , Talassemia/radioterapiaRESUMO
Generalized epileptiform seizures developed in a 23-year-old patient with beta-thalassemia-hemoglobin E. A computed tomographic scan suggested an intracranial mass. Surgery disclosed an extramedullary hematopoietic mass compressing the brain. Removal of the mass followed by irradiation of the area resulted in disappearance of the convulsions.
Assuntos
Neoplasias Encefálicas/complicações , Coristoma/complicações , Epilepsia/etiologia , Sistema Hematopoético , Talassemia/complicações , Adulto , Neoplasias Encefálicas/diagnóstico por imagem , Coristoma/diagnóstico por imagem , Epilepsia/diagnóstico por imagem , Sistema Hematopoético/patologia , Hemoglobina E/metabolismo , Humanos , Masculino , Talassemia/sangue , Talassemia/diagnóstico por imagem , Tomografia Computadorizada por Raios XRESUMO
The degree of anemia in beta(0)-thalassemia/hemoglobin E disease is highly variable. As part of an attempt to identify determinants of this variability of severity we studied concordance and discordance of hemoglobin levels among sib pairs. The distribution of differences of hemoglobin levels in 216 sib pairs from 98 families showed a remarkable skewness toward the lower values with a mode at 0-0.5 gm/dl. The prevailing concordance of hemoglobin levels in patients from the same families and the persistence of the patterns indicate that polygenic factors are mainly responsible for the variability of anemia in this disease.
Assuntos
Hemoglobinas/análise , Talassemia/genética , Feminino , Hemoglobina Fetal/análise , Hemoglobina A/análise , Hemoglobina E/análise , Humanos , Masculino , Linhagem , Fenótipo , Talassemia/fisiopatologiaRESUMO
We describe hematologic data from 18 newborn infants including follow-up data. Of these, ten were the offspring of patients with beta-thal/Hb E disease and the remainder were infants who were found to have a decrease in red cell osmotic fragility during a random cord blood examination. The results of the cord blood study showed that two infants having normal red cell osmotic fragility with about 2% Hb E + Hb A + Hb F at birth represented Hb E heterozygosity. Eleven babies had slightly decreased red cell osmotic fragility, a mild degree of microcytosis and poikilocytosis, and hemoglobin types of Hb A + Hb F with no elevation of Hb A2 at birth. They subsequently had hematologic findings consistent with the beta-thal heterozygosity. The means of hematological values of cord blood in the beta-thal trait infants appeared to be statistically different from those in the normal infants only with respect to increased red cell count and reduced MCH. One infant was thought to have the beta-thal trait but had a greater degree of thalassemic changes in red cells; subsequently he turned out to have homozygous beta-thalassemia. Four newborn infants with hypochromia and numerous target cells had 4-7% Hb E + Hb F without Hb A. Follow-up examination showed two cases of Hb E homozygosity; however, the others, who had obvious microcytosis and poikilocytosis in cord blood, finally developed beta-thal/Hb E disease. Thus, a careful study on red cell osmotic fragility, morphology and starch gel electrophoresis at birth allows detection and diagnosis of beta-thal heterozygosity, beta-thal homozygosity, Hb E heterozygosity, Hb E homozygosity and double heterozygosity for beta-thal and Hb E.
Assuntos
Sangue Fetal/análise , Hemoglobina E/genética , Hemoglobinas Anormais/genética , Talassemia/genética , Hemoglobina Fetal/análise , Hemoglobina A/análise , Hemoglobina E/análise , Hemoglobinas Anormais/análise , Heterozigoto , Homozigoto , Humanos , Recém-Nascido , Fragilidade Osmótica , Talassemia/sangue , Talassemia/diagnósticoRESUMO
At our institution, the cytomegalovirus (CMV) prophylaxis protocol for allogeneic bone marrow transplant (BMT) recipients who are CMV-seropositive or receive marrow from a CMV-seropositive donor consists of a surveillance bronchoscopy approximately 35 days posttransplant. Patients with a positive surveillance bronchoscopy for CMV receive pre-emptive ganciclovir. In order to determine the utility of other screening methods for CMV, we prospectively performed weekly CMV antigenemia, and blood, urine and throat cultures from time of engraftment to day 120 post-BMT in 126 consecutive patients. Pre-emptive ganciclovir was given to 11/81 patients (13.6%) because of a positive surveillance bronchoscopy for CMV. Results of CMV blood, urine and throat cultures and the antigenemia assay done prior to or at the time of the surveillance bronchoscopy were analyzed for their ability to predict the bronchoscopy result. The antigenemia test had the highest positive and negative predictive values (72% and 96%, respectively). The ability of these tests to predict CMV disease was evaluated in the 70 patients with a negative surveillance bronchoscopy who did not receive pre-emptive ganciclovir. Of 19 cases of active CMV disease, CMV antigenemia was positive in 15 patients (79%) a mean of 34 days preceding symptoms. Blood cultures were positive in 14/19 patients (74%) a mean of 31 days before onset of disease. CMV antigenemia is useful for predicting the surveillance bronchoscopy result, and also predicts the development of CMV disease in the majority of patients missed by the surveillance bronchoscopy.
Assuntos
Transplante de Medula Óssea/efeitos adversos , Infecções por Citomegalovirus/diagnóstico , Citomegalovirus/isolamento & purificação , Adolescente , Adulto , Antígenos Virais/sangue , Citomegalovirus/imunologia , Infecções por Citomegalovirus/sangue , Infecções por Citomegalovirus/imunologia , Infecções por Citomegalovirus/prevenção & controle , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Transplante Homólogo , Cultura de Vírus/estatística & dados numéricosRESUMO
Erythrocyte protoporphyrin (EP) was measured in 50 normal control subjects, 22 iron-responsive anemic subjects, and in 106 patients with thalassemic diseases. All normal subjects had EP of less than 80 micrograms/dL red blood cells, whereas all iron-deficiency subjects had EP of more than 80 micrograms/dL red blood cells. Six of 22 heterozygotes for thalassemias had elevated EP, and all of these had transferrin iron saturation of less than 16%, reflecting a complicating iron deficiency. Among 52 patients with beta-thalassemia/hemoglobin (Hb) E disease, 26.9% had elevated EP levels, and among 32 patients with Hb H disease, 40.6% had elevated EP. These elevated EP levels were associated with transferrin iron saturation between 18 and 44%. In none of the thalassemic patients with transferrin iron saturation above 44% was EP elevated. These findings suggest that elevation of EP in some thalassemic patients causally is related to iron supply inadequate for the massively expanded erythropoiesis. This relative iron deficiency in thalassemia occurs at a transferrin iron saturation level usually considered to be normal. These relationships demonstrate the need for an increased iron supply in patients with erythroid marrow hyperplasia, if erythropoiesis is to proceed at maximal rates.
Assuntos
Anemia Hipocrômica/complicações , Eritrócitos/análise , Porfirinas/sangue , Protoporfirinas/sangue , Talassemia/sangue , Adulto , Humanos , Talassemia/complicações , Transferrina/sangueRESUMO
Quantitative analysis of red blood cell (RBC) shapes was performed in 79 patients with beta-thalassemia/HbE disease, using scanning electron microscopy (SEM). Most patients had many abnormal RBC shapes, namely: torocytes, codocytes, dacryocytes, keratocytes, and schizocytes with a reduction in the number of normally shaped red blood cells (discocytes). Splenectomy, larger splenic sizes, and increasing anemia all were associated with a further reduction in the number of discocytes, reflecting increasing numbers of abnormally shaped RBC. The number of torocytes was increased with anemia; a larger spleen was associated with a decrease and splenectomy with an increase in the number of torocytes, indicating that they are destroyed by the spleen. The numbers of codocytes and echinocytes were singularly associated with splenectomy. Most likely, almost all of the echinocytes are destroyed by the spleen. The red blood cell types that occur as a result of RBC fragmentation, namely, dacryocytes, keratocytes, and schizocytes, were remarkably associated with the splenic status; larger splenic size was associated with an increased number of these cells, while splenectomy was associated with a noticeable reduction in their numbers. This finding confirms the role of the spleen in the fragmentation of thalassemic RBC. An increasing degree of anemia did not affect the number of codocytes and echinocytes, but was associated with a mild increase in the number of fragmented RBC and a significant increase in the number of torocytes.
Assuntos
Eritrócitos/patologia , Hemoglobina E/genética , Hemoglobinas Anormais/genética , Talassemia/sangue , Contagem de Eritrócitos , Índices de Eritrócitos , Volume de Eritrócitos , Eritrócitos/ultraestrutura , Humanos , Microscopia Eletrônica de Varredura , Baço/patologia , EsplenectomiaRESUMO
Erythrocyte superoxide dismutase activities were measured in 45 subjects, 15 each of beta 0-thalassaemia/haemoglobin (Hb) E disease, Hb H disease, and normal. The erythrocyte superoxide dismutase activities were significantly higher in the patients with beta 0-thalassaemia/Hb E and Hb H diseases than in the normal subjects. The increase of erythrocyte superoxide dismutase activities is most likely due to abnormalities specific to thalassaemic red cells rather than an increased number of younger red cells for reticulocytes and nucleated red blood cells did not affect the enzyme activity. Patients with beta 0-thalassaemia/Hb E disease with lower haemoglobin concentration had significantly higher superoxide dismutase activities. In all 45 subjects haemoglobin concentrations and superoxide dismutase activities were inversely correlated (r = -0.60 (p less than 0.001)). This indicates that the amounts of superoxide generated in the red cells may, at least partly, determine severity of red cell damage and thus severity of disease; the increased superoxide dismutase activity in thalassaemia is a response to superoxide generated in greater amounts because of accumulation of excessive globin chains and iron in the red cells. The superoxide dismutase activities in Hb H disease, an alpha-thalassaemic disease, were found to be strikingly increased, higher than in beta 0-thalassaemic disease or other conditions.
Assuntos
Eritrócitos/enzimologia , Hemoglobina E , Hemoglobinopatias/enzimologia , Hemoglobinas Anormais , Superóxido Dismutase/sangue , Talassemia/enzimologia , Anemia Hemolítica Autoimune/sangue , Anemia Hemolítica Autoimune/enzimologia , Hemoglobinopatias/sangue , Humanos , Esplenectomia , Talassemia/sangueRESUMO
The activities of erythrocyte antioxidative enzymes were measured in two groups of patients with different genotypes of haemoglobin (Hb) H disease: 21 with alpha-thalassaemia 1 or alpha-thalassaemia 2 (alpha-thalassaemia 1/2) and 21 with alpha-thalassaemia 1/Hb Constant Spring (HbCS). They were compared with 21 normal subjects. Both genotypes of Hb H disease had increased activities of erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase when compared with those of controls. Comparison of the two genotypes showed that subjects with alpha-thalassaemia 1/Hb CS, the more severe disease, had higher SOD and GSH-Px activities but lower catalase activity than those with alpha-thalassaemia 1/2. This indicates that there are compensatory mechanisms in Hb H erythrocytes to cope with increased generation of oxygen free radicals as a result of increased excess beta chain.
Assuntos
Catalase/sangue , Eritrócitos/enzimologia , Glutationa Peroxidase/sangue , Superóxido Dismutase/sangue , Talassemia/enzimologia , Genótipo , Hemoglobinas Anormais , Humanos , Talassemia/sangueRESUMO
beta (0)-Thalassemia/Hb E in Southeast Asia varies greatly in severity, with hemoglobin levels ranging from 2.5 to 13.5 g/dl, averaging 7.7 g/dl. Results of systematic investigations to find out what determines different levels of severity are reviewed. Concomitant inheritance of alpha-thalassemia significantly decreases the severity. Different degrees of severity in the majority of cases, however, is not due to alpha-thalassemia. Concordance of hemoglobin levels among patients who are sibs prevails, suggesting polygenic factor determinants. Potential factors ruled out as determinants for different levels of severity are discriminating fetal hemoglobin production, erythrocyte superoxide dismutase activity, reticulo-endothelial function, and failure of erythropoiesis compensation. Red cell survival and globin synthesis studies indicate that different degrees of excess of alpha-chains leading to different red cell pathology and survival are responsible for variable severity. Degrees of excess of alpha-chains in this circumstance are probably mainly determined by erythrocyte proteolytic activity. The relationship between the hemoglobin levels and erythrocyte cytosol proteolytic activity in 15 beta(0) -thalassemia/Hb E disease patients in whom a deletional type of alpha-thalassemia had been ruled out by DNA mapping is striking, with a correlation coefficient of 0.78. This finding suggests that modulation of erythrocyte proteolysis is another approach for treatment of thalassemia.
Assuntos
Talassemia/fisiopatologia , Sudeste Asiático , DNA/genética , Envelhecimento Eritrocítico , Eritrócitos/enzimologia , Eritrócitos/fisiologia , Globinas/biossíntese , Globinas/genética , Hemoglobina E/biossíntese , Humanos , Ferro/sangue , Cinética , Sistema Fagocitário Mononuclear/fisiopatologia , Peptídeo Hidrolases/metabolismo , Superóxido Dismutase/metabolismo , Talassemia/sangue , Talassemia/genéticaRESUMO
Human genome research which tries to map and sequence all the 3 billion nucleotides in the entire DNA is progressing rapidly. Completion of the human genome sequencing is expected before the year 2005. Human genes, totalling 50,000-100,000, will be identified, allowing the complete set of proteins--'the proteome' to be known. This together with genomic research in other species will lead to complete understanding of life at the molecular level and also its evolutionary history of 3,500 million years. Genomics will bring about a revolution in biology and health, because it is equivalent to having a 'Biological Periodic Table' which is a foundation for understanding life, health, disease and for deriving of new tools for diagnosis, treatment, prognosis and prevention. Human genomics will give rise to Predictive--Preventive Medicine and Precision Medicine. It will have profound social implications. Preparation for the future is needed for societies to cope with and make proper use of the tremendous changes to be brought about by genomics.
Assuntos
Saúde Global , Projeto Genoma Humano , Sudeste Asiático , Previsões , Planejamento em Saúde , História do Século XX , Projeto Genoma Humano/história , Humanos , Biologia Molecular/história , Biologia Molecular/tendências , Talassemia/genética , Talassemia/históriaRESUMO
Alpha thalassemia is the most common single gene mutation worldwide. In Thailand there exists 15-30% alpha-thalassemia carriers distributed throughout the country. DNA analysis by Southern blot hybridization reveals that the two major alpha-thalassemia alleles, alpha-thalassemia 1 and alpha-thalassemia 2 have different extents of alpha-globin gene deletion. In alpha-thalassemia 1, approximately 20 kb of DNA including the two linked alpha 1-and alpha 2-genes are removed and only the alpha-globin gene is intact. Total deletion of the alpha-globin gene cluster is rarely observed. In contrast, only one alpha-globin gene is deleted in alpha-thalassemia 2 of which two types have been detected, one involving a deletion of 4.2 kb of DNA (leftward type, -alpha 4.2) and another of 3.7 kb (rightward type, -alpha 3.7); the latter being more common than the former in Thailand. Compound heterozygosity for alpha-thalassemia 1 and alpha-thalassemia 2 results in HbH disease while homozygosity for alpha-thalassemia 1 leads to Hb Bart's hydrops fetalis, the most severe form of thalassemic disease. Three alpha-thalassemic hemoglobinopathies have been detected in Thailand, two of which produce a remarkable reduction in gene product. Upon interacting with alpha-thalassemia 1 gene they can lead to HbH disease. The most common in this group is Hb Constant Spring which arises from mutation of the termination codon in the alpha 2-gene resulting in an elongation of the alpha-globin chain.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Deleção de Genes , Globinas/genética , Mutação/genética , Talassemia alfa/genética , Eletroforese das Proteínas Sanguíneas , Southern Blotting , Índices de Eritrócitos , Frequência do Gene , Hemoglobina H , Hemoglobinopatias/congênito , Hemoglobinopatias/epidemiologia , Hemoglobinopatias/prevenção & controle , Hemoglobinas Anormais , Heterozigoto , Homozigoto , Humanos , Hidropisia Fetal/epidemiologia , Hidropisia Fetal/etiologia , Hidropisia Fetal/prevenção & controle , Recém-Nascido , Programas de Rastreamento , Fenótipo , Reação em Cadeia da Polimerase , Diagnóstico Pré-Natal , Tailândia/epidemiologia , Talassemia alfa/classificação , Talassemia alfa/epidemiologiaRESUMO
Examination for circulating platelet aggregates according to Wu and Hoak revealed increased circulating platelet aggregates in 71% of splenectomized and 35% of nonsplenectomized patients with beta (0)-thalassaemia/Hb E disease. This may be causally related to the newly observed high incidences of pulmonary artery thrombosis and hypoxaemia in splenectomized thalassaemic patients. It is recommended that anti-platelet aggregation drugs such as aspirin and/or dipyridamole are given to thalassaemic patients after splenectomy.
Assuntos
Agregação Plaquetária , Talassemia/sangue , Humanos , Contagem de Plaquetas , Esplenectomia , Trombocitose/complicaçõesRESUMO
Blood gas analysis of arterial blood was performed in 34 patients with beta o-thalassaemia/haemoglobin E disease and homozygous beta o-thalassaemia. Among the 22 splenectomised patients 19 had PaO2 lower than the normal expected value, and 18 of these had PaO2 lower than 80 mmHg. Of the 12 non-splenectomised patients 5 had PaO2 lower than the expected normal value but only in one case it was lower than 80 mmHg. After aspirin or Persantin administration there was a definite rise in the PaO2 in 10 out of 12 patients. The hypoxaemia is believed to occur from increased platelet aggregation leading to pulmonary artery occlusion. The rise of the arterial PaO2 after aspirin administration indicates that the observed hypoxaemia is due to reversible platelet aggregation in the majority of cases.
Assuntos
Aspirina/uso terapêutico , Hipóxia/complicações , Talassemia/complicações , Adolescente , Adulto , Dipiridamol/uso terapêutico , Feminino , Humanos , Hipóxia/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Esplenectomia , Talassemia/tratamento farmacológicoRESUMO
Autopsy protocols and heart slides of 47 patients with beta thalassaemia/haemoglobin E disease were reviewed. All but 1 patient had cardiac hypertrophy, accompanied by dilatation in 17; 5 of 9 patients (56%) with right ventricular and 11 of 22 patients (50%) with biventricular hypertrophy had chronic pulmonary thromboembolism. Cardiac iron deposition while present in 15 patients (32%) was very slight, in contrast to the amount of iron in their liver and pancreas. Four patients had fibrinous pericarditis, 2 with rheumatic heart disease. Twelve patients had chronic pericardial changes, 7 with adhesive pericarditis. The effects of cardiac pathology on the morbidity and mortality of patients with beta thalassaemia/haemoglobin E disease were discussed.
Assuntos
Cardiopatias/patologia , Hemoglobina E , Hemoglobinas Anormais , Talassemia/complicações , Adolescente , Adulto , Idoso , Cardiomegalia/complicações , Cardiomegalia/patologia , Criança , Pré-Escolar , Feminino , Cardiopatias/complicações , Doenças das Valvas Cardíacas/complicações , Doenças das Valvas Cardíacas/patologia , Humanos , Lactente , Ferro/análise , Masculino , Pessoa de Meia-Idade , Miocárdio/metabolismo , Miocárdio/patologia , Pericardite/complicações , Pericardite/patologia , Talassemia/sangue , Talassemia/metabolismoRESUMO
Thrombocytosis and morphological changes in shape and size of circulating platelets are commonly found in splenectomized thalassemia patients. Functional abnormalities of the platelets are evidently related to their fragile nature. Spontaneous aggregation of platelets can easily occur following application of mild pressure either from a stirring magnetic bar or due to centrifugal force. Platelets are hyper-reactive to chemical stimulation and the release of platelet granule contents (eg ATP) together with other membranous lipid metabolites, thromboxane A2 and malondialdehyde is markedly enhanced. The lipid soluble antioxidant, vitamin E is depleted from various blood compartments. The findings suggest that circulating platelets in splenectomized thalassemia are continuously attacked by yet to be identified blood borne factor(s) and the defective platelets could play a pivotal role in the pathogenesis of hypoxemia.
Assuntos
Hemoglobina E , Hemoglobinopatias/complicações , Hipóxia/sangue , Agregação Plaquetária , Complicações Pós-Operatórias/sangue , Esplenectomia , Talassemia beta/complicações , Estudos de Casos e Controles , Hemoglobinopatias/cirurgia , Humanos , Hipóxia/epidemiologia , Hipóxia/etiologia , Incidência , Malondialdeído/sangue , Contagem de Plaquetas , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Esplenectomia/efeitos adversos , Tailândia/epidemiologia , Tromboxano B2/sangue , Vitamina E/sangue , Talassemia beta/cirurgiaRESUMO
Partial purified erythrocyte G-6-PD from 25 G-6-PD deficient southern Chinese male residents in Thailand was characterized. Five G-6-PD variants were found : G-6-PDs Canton (8), Dhon (or Taipei-Hakka) (8), Mahidol (or B (-) Chinese) (6), Haad Yai (1), and Hong Kong (1). One person whose enzyme was not fully characterized might have G-6-PD Haad Yai or a new variant.