Rapid immunoassays for the measurement of immunoglobulin G subclass concentration in immunoglobulin preparations and human serum.

Enzyme immunoassays (EIA) capable of determining total IgG1, IgG2, IgG3 and IgG4 subclass concentrations in human serum preparations have been developed. Subclass-specific monoclonal antibodies (mAbs) are bound to polyacrylamide bead-conjugated anti-mouse immunoglobulin antibodies. Bound immunoglobulins are detected with a peroxidase-conjugated anti-IgG antibody or a biotin-conjugated anti-IgG antibody followed by peroxidase streptavidin. The standard curves were found to be linear in the regions 16.0-2.0 micrograms/ml for IgG1, 4.0-0.5 micrograms/ml for IgG2, 0.4-0.06 micrograms/ml for IgG3 and 0.25-0.05 micrograms/ml for IgG4. Coefficient of variation (CV) values range from 0.32-7.32% for IgG1, 0.66-4.85% for IgG2, 1.62-6.85% for IgG3 and 0.05-6.47% for IgG4 standard curves. The inter-assay variability for the control human serum samples was 9.6% for IgG1, 6.7% for IgG2, 9.5% for IgG3 and 6.8% for IgG4.     

Randomized placebo-controlled study of low-dose warfarin for the prevention of central venous catheter-associated thrombosis in patients with cancer.

PURPOSE: In this multicenter, randomized, placebo-controlled clinical trial, we studied whether warfarin 1 mg daily reduces the incidence of symptomatic central venous catheter (CVC) -associated thrombosis in patients with cancer. PATIENTS AND METHODS: Two hundred fifty-five patients with cancer who required a CVC for at least 7 days were randomly assigned to receive warfarin 1 mg or placebo. RESULTS: There were 11 (4.3%) symptomatic CVC-associated thromboses among 255 patients, with no difference in the incidence of symptomatic CVC-associated thrombosis between patients taking warfarin 1 mg daily (six of 130 patients; 4.6%) and patients taking placebo (five of 125 patients; 4.0%; hazard ratio, 1.20; 95% CI, 0.37 to 3.94). Warfarin had no effect on CVC life span (84 days v 63 days in control and warfarin groups, respectively; 95% confidence limit, -16 to 55 days; P = .09), and it did not affect the number of premature CVC removals (23.2% v 25.4% in control and warfarin groups, respectively; 95% confidence limit of difference -8.34 to 12.71; P = .68) or the frequency of major bleeding episodes (2% v 0% in control and warfarin groups, respectively; P = .5, Fisher's exact test). CONCLUSION: Symptomatic CVC-associated thrombosis in patients with cancer, although significant, is less common than previously reported. In this study, the administration of warfarin 1 mg daily did not reduce the incidence of symptomatic CVC-associated thrombosis in patients with cancer. However, the low rate of symptomatic CVC-associated thrombosis means that a much larger trial is required to address this issue definitively.     

The Pattern of Disordered Haemoglobin Synthesis in Homozygous and Heterozygous β-Thalassaemia*

The rate of globin chain production has been studied in patients with homozygous β-thalassaemia, heterozygous β-thalassaemia, haemoglobin E-thalassaemia, and sickle-cell-thalassaemia, and compared with that in non-thalassaemic individuals. A partial or total deficit of β-chain synthesis has been demonstrated in all forms of β-thalassaemia. This results in the production of a large intracellular pool of α-chains, the kinetics of which have been worked out. The α-chains in this pool appear to contain haem and are unstable, rapidly becoming associated with the stromal fraction. These findings are examined in terms of the pathogenesis of the anaemia of thalassaemia.     

Insecticidal Activities of the Leaf Oils of Eight Cinnamomum. species Against Aedes aegypti. and Aedes albopictus.

Abstract

The leaf oils of eight Cinnamomum. species (C. rhyncophyllum. Miq., C. microphyllum. Ridl., C. pubescens. Kochummen, C. mollissimum. Hook. f., C. impressicostatum. Kosterm, C. scortechinii. Gamb., C. sintoc. Bl., and C. cordatum. Kosterm) were investigated for their larvicidal and adulticidal activities against Aedes aegypti. (Aedes aegypti Lynn) and Aedes albopictus. (Aedes albopictus Skuse). Acute mortalities of the fourth instar larvae and the adult mosquitoes were determined according to the standard WHO methods. Among the essential oils studied, the leaf oils of C. rhyncophyllum., C. microphyllum., C. pubescens., C. mollissimum., and C. impressicostatum. showed significant effects against the larvae of Ae. aegypti. and Ae. albopictus. with concentrations that caused 50% mortality (LC₅₀) values of less than 12.8 and 11.8 µg ml^?1, respectively. The essential oils that showed strong larvicidal effects also demonstrated relatively strong adulticidal effects on the mosquitoes after 3 h exposure with LC₅₀ values ranging from 133.0 to 243.0 µg ml^?1 against Ae. aegypti. and from 118.0 to 194.0 µg ml^?1 against Ae. albopictus.. The efficacy of the oils toward the larvae and adult mosquitoes of both species was nonselective as the LC₅₀ values showed little variation. The chemical composition of the oils was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). This study suggested that the essential oils containing high levels of benzyl benzoate and benzyl salicylate exhibited strong insecticidal activities against the larvae and adult mosquitoes.     

Ultrastructure and cell cycle distribution of erythropoietic cells in heterozygotes and homozygotes for haemoglobin E

S ummary. Marrow aspirates from heterozygotes and homozygotes for haemoglobin E (HbE) have been studied by electron microscopy and by the technique of combined Feulgen microspectrophotometry and ³H-thymidine autoradiography. The erythropoietic cells of heterozygotes did not contain any precipitated globin chains and the proliferating erythroblasts of such individuals showed no abnormality in their distribution in the different stages of interphase. By contrast, 0–1.5% of late erythroblast profiles and 3.1–12.8% of marrow reticulocyte profiles of homozygotes contained intracellular inclusions resembling precipitated α-chains. Although precipitated globin chains were not seen in the early polychromatic erythroblasts of homozygotes, the number of these cells in the G2 phase relative to that in the S phase was increased. These data indicate that there is (1) probably little or no imbalance of globin chain synthesis in heterozygotes, (2) a substantial degree of imbalance in homozygotes, and (3) a disturbance of erythroblast proliferation in homozygotes which cannot be attributed to the deleterious effects of detectable intracellular α-chain precipitates. The electron microscope and cell cycle distribution data in the homozygotes for HbE were similar to those in two heterozygotes for β thalassaemia.     

Incidence and risk factors for pulmonary tuberculosis among the poor in the northern region of Poland

SETTING: The falling trends in pulmonary tuberculosis (PTB) incidence observed in European countries may be due both to an improving epidemiological situation and to a shift of tuberculosis (TB) towards socially important subpopulations; this trend may cause some TB cases to go unnoticed. Identification of such risk groups should be the basis for prevention programmes aimed at containing the spread of the disease. OBJECTIVE: To evaluate the incidence and risk factors for PTB among the poor. DESIGN: The study material was based on the data of 7380 people living in poverty, including 243 homeless adults, aged between 18 and 96 years. Potential medical and socio-economic risk factors were evaluated with regard to PTB incidence. RESULTS: The TB incidence rate in the group studied was estimated at 730 per 100,000 population. The main risk factor was homelessness, with a TB incidence rate in the homeless group of 4290/100,000. According to our data, socio-economic factors correlated much more closely with a final TB diagnosis than subjective disease symptoms. CONCLUSIONS: Efficient TB control requires prevention programmes aimed at systematic monitoring of the homeless. A population with such a high proportion of TB patients is a dangerous source of TB.     

The prevalence and persistence of human parvovirus B19 infection in thalassemic patients

Human parvovirus B19 infection was studied in 60 thalassemic patients in Thailand. Seroprevalence, persistence of parvovirus B19 and their genotypes were identified in blood samples. Prevalence of anti-parvovirus B19 IgG and DNA found in thalassemic patients were 38% and 13%, respectively. Anti-parvovirus B19 IgM could be detected in 4% of these positive anti-parvovirus B19 IgG patients. The seroprevalence and parvovirus B19 DNA in patients with a history of blood transfusion were not significantly higher than those without such a history (44% vs. 34% and 20% vs. 9%, respectively). Phylogenetic analysis of NS1 nucleotide sequences of three parvovirus B19 samples revealed that they were parvovirus B19 genotype 1. They showed low genetic diversity from prototype (Au) strain. We concluded that acute and chronic persistent parvovirus B19 infection were found in the thalassemic Thai patients. Chronic persistence of parvovirus B19 infection might play important clinical role in thalassemic patients because of the high prevalence of parvovirus B19 DNA. Blood transfusion had no significant influence to increase the prevalence of parvovirus B19 infection in thalassemic patients.     

Serum ferritin levels in thalassemias and the effect of splenectomy

Iron overload is a constant and the more important complication in thalassemia. Serum ferritin concentration accurately reflects body iron stores. A total of 245 thalassemic patients aged 12-55 years were examined, 71 having Hb H disease and 174 beta-thalassemia/Hb E disease. The patients received minimal or no blood transfusions. 73 patients with beta-thalassemia/Hb E were studied 1-28 years after splenectomy. The serum ferritin levels in both Hb H and beta-thalassemia/Hb E patients were higher than normal. They were higher in beta-thalassemia/Hb E than Hb H disease. Most striking was the significantly higher serum ferritin levels in splenectomized patients with beta-thalassemia/Hb E disease than in the nonsplenectomized ones. The observation is compatible with previous observations that splenectomy in thalassemia is associated with increased iron deposition and increased transferrin iron saturation. The further increase in iron overload after splenectomy in thalassemia should be borne in considering removal of this organ.     

A correlation of erythrokinetics, ineffective erythropoiesis, and erythroid precursor apoptosis in thai patients with thalassemia

The variety of patients with thalassemia in Thailand offers an opportunity to fully characterize the kinetic causes of the anemia and to study apoptosis of marrow erythroid precursors as a possible factor contributing to its severity. Kinetic studies showed that in hemoglobin H (HbH) disease, the extent of hemolysis, as well as the minimally ineffective erythropoiesis, usually falls within the compensatory capacity of normal erythropoiesis; therefore, anemia in patients with HbH partly represents a failure to expand erythropoiesis adequately. Hemoglobin Constant Spring (HbCS), a common variant of alpha thalassemia in Bangkok, causes more severe hemolysis and a distinct increase in ineffective erythropoiesis. Ineffective erythropoiesis plays a much more prominent role in beta thalassemia/hemoglobin E (beta-thal/HbE) disease, in which the variability of the anemia is puzzling. We compared mild and severe cases and found that patients with severe disease had a maximal marrow erythropoietic response that failed to compensate for very short survival of red blood cells and a marked quantitative increase in ineffective erythropoiesis. Analysis of apoptosis of marrow erythroid precursors done both on shipped samples and in Bangkok showed a moderate increase in HbH disease, consistent with the small increase in ineffective erythropoiesis. In patients with homozygous HbCS, there was a further increase in apoptosis, consistent with the additional increase in ineffective erythropoiesis. Patients with beta-thal/HbE disease had the most ineffective erythropoiesis and the most erythroid apoptosis. Thus, it appears that alpha-chain deposition in erythroid precursors, either alpha(A) or alpha(cs), leads to accelerated apoptosis and ineffective erythropoiesis.     

Genetic factors affecting clinical severity in beta-thalassemia syndromes

PURPOSE: Heterogeneity in the clinical manifestation of beta-thalassemic diseases may occur from the nature of beta-globin gene mutations, alpha-thalassemia gene interaction, or differences in the amount of hemoglobin (Hb) F production. This study was conducted to determine whether these genetic determinant factors can predict phenotypic severity of patients with beta-thalassemia and to assess the relationship between the genotype and phenotype of the disease. MATERIALS AND METHODS: A total of 144 patients with beta-thalassemia were divided into mild (46 patients), intermediate (55 patients), and severe groups (43 patients). DNA analysis based on polymerase chain reaction technique was performed to characterize types of beta-thalassemia mutation, interaction of alpha-thalassemia, and XmnI polymorphism 5' to Ggamma-globin gene. RESULTS: Two alleles of mild beta-thalassemia mutation (beta+/beta+-thalassemia or beta+-thalassemia/Hb E) resulted in a mild clinical symptom whereas two alleles of severe beta-thalassemia mutation (betao/betao) produced a severe clinical phenotype. Compound heterozygosity for mild and severe alleles of beta-thalassemia (betao/ beta+-thalassemia or betao-thalassemia/Hb E) led to variable severity of anemia. Coinheritance of alpha-thalassemia alleviated the severity of beta-thalassemia disease in those patients with at least one allele of the mild beta-thalassemia genotype. DNA polymorphism at position-158 nt 5' to the Ggamma-globin gene was demonstrated by XmnI restriction enzyme. Homozygote of the XmnI site, +/+, was found to have a strong linkage with high Hb F levels and high hemoglobin production in two patients who had mild clinical symptoms. However, some patients who had XmnI site -/- also had mild clinical symptoms because the XmnI- was found to be associated with beta+-thalassemia mutation. CONCLUSION: Types of beta-thalassemia mutation and coinheritance of alpha-thalassemia in the patient who has at least one allele of the mild beta-thalassemia genotype are predictive for the clinical severity of the disease. However, a mild clinical symptom in some patients with betao/beta+-thalassemia or betao-thalassemia/Hb E who do not have a detectable alpha-thalassemia haplotype and no linkage with XmnI++ suggests that there are other confounding factors responsible for the severity differences of the disease.