Human herpes virus 6 antibodies in beta-thalassemia/hemoglobin E pediatric patients.

Human herpesvirus 6 (HHV-6) is a viral pathogen that causes exanthem subitum in children. It has also been identified as the cause of life-threatening illness in immunocompromised pediatric patients and transplant recipients. We undertook a serological study of HHV-6 IgM and IgG antibody among 29 children (12 females and 17 males) with beta-thalassemia/HbE disease. The rate of infection was 86.2%; the rates of early recent infection (IgM positive only), recent infection (both IgM and IgG positive) and past infection (IgG positive only) were 13.8%, 41.4% and 31.0%, respectively. The geometric means of the IgM and IgG titers of the splenectomy group (9 cases) were 10.15 units and 11.18 units, respectively. The geometric means of the IgM and IgG titers of the non-splenectomy group (20 cases) were 10.10 units and 12.84 units, respectively. According to this study, the prevalence of HHV6 infection among pediatric patients with beta-thalassemia/HbE is very high; morever, the significantly higher titer among these patients may imply a high risk for further possible bone marrow transplantation. Increased awareness of HHV-6 infection among this population is necessary.

The value of methemoglobin reduction test as a screening test for neonatal glucose 6-phosphate dehydrogenase deficiency.

Glucose 6-phosphate dehydrogenase (G-6-PD) deficiency is common in the Thai population and is the cause of neonatal hyperbilirubinemia and hemolytic anemia. This X-linked disorder is much more common in males than females. The objectives of this study were to compare the result of the screening methemoglobin reduction test (MRT) with the gold standard G-6-PD activity, and also to determine the prevalence of G-6-PD deficiency in the cord blood and blood of neonates with hyperbilirubinemia. Five hunderd and twenty two randomly selected cord blood (350 males, 172 females) and 229 peripheral blood from neonates with hyperbilirubinemia were assayed for G-6-PD enzyme activity using a WHO-recommended standard test as well as methemoglobin reduction (MR) test. The results showed that prevalence of G-6-PD deficiency from the cord blood was 11.1 per cent in males, and 5.59 per cent in females. Among newborns with neonatal jaundice, the prevalence of G-6-PD deficiency was 22.1 per cent in males and 10.1 per cent in females. MRT in cord blood G-6-PD deficiency screening had acceptable sensitivity (85.7%) and high specificity (98.1%). The sensitivity of MRT in jaundiced infants was low (60.0%) whereas the specificity was acceptable (92.1%). The negative predictive values were more than 90 per cent while the positive predictive values were low (61-65%) from both specimens. Conclusions: G-6-PD deficiency is common in the Thai population, both in males and females and can be screened from cord blood by using low cost MRT. G-6-PD deficiency contributes to 20 per cent of neonatal jaundice, and screening with MRT yields low sensitivity.

Molecular cloning of phospholipase A2 from a Thai Russell's viper venom gland cDNA library.

Snake venom contains several toxins. Russell's viper (D. russellii, RV) is a venomous snake prevalent in northern and central Thailand. RV bites can cause disseminated coagulation, hemolysis, and edema of the bitten limbs. To identify protein components of RV venom, we made a cDNA library from RV venom glands, and randomly sequenced cloned cDNA. We were able to clone a cDNA encoding RV phospholipase A2 (PLA2). PLA2 is an active enzyme found in several species of snake venom worldwide. PLA2 is thought to be toxic to cell membrane, thereby, can cause local cell and tissue damage, as well as systemic effects in snake bite victims. This PLA2 cDNA clone would facilitate in vivo studies of the pathophysiology of RV bite.

Optic nerve glioma in infancy: a case report of the youngest patient in Thailand.

A 4-month-old infant came to the department of Ophthalmology, King Chulalongkorn Memorial Hospital with right eye proptosis, strabismus, and no vision. She was diagnosed as optic nerve and chiasm glioma. The subtotal removal of the tumor was performed and followed by chemotherapy, with a satisfactory result. Because of the large size of the tumor and the presenting symptoms and signs since the patient was only 2 month old, we believe that this tumor originated in the intrauterine period. To our knowledge, this reported case is the youngest patient with optic nerve and chiasm astrocytoma in Thailand.

Low dose intravenous immunoglobulin for acute immune thrombocytopenic purpura in children.

Acute immune thrombocytopenic purpura (ITP) is a self-limited autoimmune disorder to platelets. The disease responds well to intravenous immunoglobulin (IVIG) treatment. We studied the efficacy of low dose (1 g/kg) IVIG to treat acute ITP in children. Of 17 children with ITP and platelet counts < 20,000/microl, 13 (76%) had rapid platelet count recovery, reaching safe level (> 50,000/microl) within 4 days after 1 g/kg IVIG. Four children needed a second dose. In 5 of 15 patients, platelet counts recovered to normal without recurrence, while in 10 patients, platelet counts declined again 2-3 weeks after the initial treatment; 6 of whom (40%) needed re-treatment. All but one patient had complete recovery of the platelet count by 6 months. Adverse effects of low dose IVIG were minimal. We recommend that for childhood ITP, 1 g/kg IVIG should be tried initially. If inadequate response is seen (platelet count < 30,000/microl) by 48 hours, a second dose is needed.

Hepatocellular carcinoma: significance of HBV vertical transmission.

In two cases of childhood hepatocellular carcinoma in Thailand, we established vertical transmission of hepatitis B virus infection as the underlying cause. With the first patient, the family history of HBV carriage became evident and a pedigree could be devised which demonstrated the high prevalence among the family members and hence evidence of vertical transmission. In the case of the second patient, we performed PCR and subsequent direct sequencing of HBV DNA isolated from his HBsAg-positive mother's, as well as from his serum, comparing the nucleotide sequences with those of a pregnant woman diagnosed as an asymptomatic HBV carrier, of another asymptomatic HBV carrier and of a reference strain, respectively, all belonging to the same genotype and subtype as the samples tested. Our results clearly indicate the necessity for nation-wide hepatitis B vaccination starting at birth, at least in hyperendemic areas like the Far East, in order to forestall HBV carriage and ensuing cirrhosis and/or HCC by preventing vertical transmission.

Immunophenotyping of acute lymphoblastic leukemia in pediatric patients by three-color flow cytometric analysis.

Immunophenotyping of acute lymphoblastic leukemia (ALL) in children using three-color flow cytometry was carried out at Chulalongkorn Hospital, Bangkok, Thailand. Of 38 patients with acute lymphoblastic leukemia, 65.8% were identified as common ALL, 15.8% were B-ALL, and 18.4% were T-ALL. Of these 38 cases, there were 4 cases of infantile leukemia. Relapsed cases of leukemia were found most in B-ALL up to 3 out of 6 cases and to a lesser extent in T-ALL (1 of 7 cases) and c-ALL (1 of 25 cases). Our data showed the CD markers expression for common ALL (c-ALL) were CD19+/10+ (100%), CD20+ (24%), CD22+ (100%), HLA-DR+ (70.1%), and CD34+ (58.8%). CD markers expression for B-ALL were CD19+ (100%), CD20+ (33.3%), CD22+ (80%), and HLA-DR+ (80%). CD markers expression for T-ALL were CD3+ (42.9%), CD5+ (100%), CD7+ (85.7%). Myeloid aberrant expressions were found in c-ALL (25-37.5%), B-ALL (20%), and T-ALL (14.3%). The significance of the aberration is discussed. The immunophenotyping classification of ALL as c-ALL, B-ALL, and T-ALL is useful in prognosis and treatment.

Eosinophilia, anemia and parasitism in a rural region of northwest Thailand.

Parasitic infections are prevalent in Thailand. The parasites' relationship with anemia and eosinophilia has been rarely reported due to limited health care access, especially in rural areas. We studied the prevalence and relationship between eosinophilia, anemia and parasitism in 169 Thai-Karens from Mae Lamung and Mae Chan subdistricts, Umphang district, Tak Province, using an automated complete blood counter, and microscopic examination for intestinal parasites and microfilaria. In Mae Chan, 5 individuals were microfilaremic, 72% of individuals examined were infected with at least one kind of intestinal parasites, and 50% were anemic, with normal mean red cell volume (MCV). In Mae Lamung, 46% were parasitized (Triteeraprapab et al, 1997) but none were microfilaremic or anemic. In both populations, eosinophilia was prevalent (77%). Hookworm infection was found to be significantly associated with eosinophilia, but not anemia nor microcytosis of red cells.

Clinical training opportunities for Thai medical graduates in the United States.

There are many opportunities for a foreign medical graduate to receive graduate medical education in the US. It is unclear whether the chance is increasing or decreasing. Careful planning requires around a year in advance.