Asymptomatic primary Epstein-Barr virus infection occurs in the absence of blood T-cell repertoire perturbations despite high levels of systemic viral load

Primary infection with the human herpesvirus, Epstein-Barr virus (EBV), may result in subclinical seroconversion or may appear as infectious mononucleosis (IM), a lymphoproliferative disease of variable severity. Why primary infection manifests differently between patients is unknown, and, given the difficulties in identifying donors undergoing silent seroconversion, little information has been reported. However, a longstanding assumption has been held that IM represents an exaggerated form of the virologic and immunologic events of asymptomatic infection. T-cell receptor (TCR) repertoires of a unique cohort of subclinically infected patients undergoing silent infection were studied, and the results highlight a fundamental difference between the 2 forms of infection. In contrast to the massive T-cell expansions mobilized during the acute symptomatic phase of IM, asymptomatic donors largely maintain homeostatic T-cell control and peripheral blood repertoire diversity. This disparity cannot simply be linked to severity or spread of the infection because high levels of EBV DNA were found in the blood from both types of acute infection. The results suggest that large expansions of T cells within the blood during IM may not always be associated with the control of primary EBV infection and that they may represent an overreaction that exacerbates disease. (C) 2001 by The American Society of Hematology.

Incubation temperature, energy expenditure and hatchling size in the green turtle (Chelonia mydas), a species with temperature-sensitive sex determination

Eggs from the Heron Island, Great Barrier Reef, nesting population of green turtles (Chelonia mydas) were incubated at all-male-determining (26 degreesC) and all-female-determining (30 degreesC) temperatures. Oxygen consumption and embryonic growth were monitored throughout incubation, and hatchling masses and body dimensions were measured from both temperatures. Eggs hatched after 79 and 53 days incubation at 26 degreesC and 30 degreesC respectively. Oxygen consumption at both temperatures increased to a peak several days before hatching, a pattern typical of turtle embryos, and the rate of oxygen was higher at 30 degreesC than 26 degreesC. The total amount of energy consumed during incubation, and hatchling dimensions, were similar at both temperatures, but hatchlings from 26 degreesC had larger mass, larger yolk-free mass and smaller residual yolks than hatchlings from 30 degreesC. Because of the difference in mass of hatchlings, hatchlings from 30 degreesC had a higher production cost.

Effect of hemochromatosis genotype and lifestyle factors on iron and red cell indices in a community population

Background: Heterozygotes for the C282Y mutation of the HFE gene may have altered hematology indices and higher iron stores than wild-type subjects. Methods: We performed a cross-sectional analysis of 1488 females and 1522 males 20-79 years of age drawn from the Busselton (Australia) population study to assess the effects of HFE genotype, age, gender, and lifestyle on serum iron and hematology indices. Results: Male C282Y heterozygotes had increased transferrin saturation compared with the wild-type genotype. Neither male nor female heterozygotes had significantly increased ferritin values compared with the wild-type genotype. Younger (20-29 years) wild-type males, but not heterozygous males, had significantly lower ferritin values than wild-type males in the older age groups. Compound heterozygous subjects had increased means for serum iron, transferrin saturation, corpuscular volume, and corpuscular hemoglobin compared with the wild-type genotype, and the males also had increased ferritin values (medians 323 vs 177 mug/L; P = 0.003). In both male and female wild-type subjects, an increased body mass index was associated with decreased serum iron and transferrin saturation and increased ferritin values. There was a significant increase in ferritin concentrations in both genders with increasing frequency of red meat consumption above a baseline of 1-2 times per week and alcohol intakes >10 g/day. Conclusions: Male C282Y heterozygotes had significantly increased transferrin saturation values. Compound heterozygous (C282Y/H63D) subjects formed a separate category of C282Y heterozygotes in whom both iron and red cell indices were significantly increased compared with the wild-type genotype. (C) 2001 American Association for Clinical Chemistry.

Combination therapy with tacrolimus and anti-thymocyte globulin for the treatment of steroid-resistant acute graft-versus-host disease developing during cyclosporine prophylaxis

We report our experience with the combination of anti-thymocyte globulin (ATGAM) and tacrolimus in the treatment of 20 patients with steroid refractory and dependent acute graft-versus-host disease (GVHD) transplanted between August 1996 and February 2000. All patients received cyclosporine-based GVHD prophylaxis. Thirteen patients developed a maximum of grade TV, five grade III and two grade II acute GVHD, with 15 patients being refractory to steroids and five dependent on steroids. Patients were treated with ATGAM (15 mg/kg for 5 d) and tacrolimus (0.025-0.1 mg/kg/d) in addition to continuation of their high-dose steroids and cessation of their cyclosporine. Within 28 d of treatment, we observed eight complete responses (CR), six partial responses (PR) and six with no response. Overall response (CR + PR) was predicted by GVHD severity. Infectious complications occurred in 80% of patients. The median survival was 86.5 d (range, 21-1081 d) with 35% of patients remaining alive, Survival following combination therapy was significantly more likely in men (P < 0.001), skin-only GVHD (P = 0.027), less severe GVHD (P = 0.048), and in responders to tacrolimus and ATGAM (P< 0.001). In conclusion, concurrent introduction of ATGAM and tacrolimus is a promising therapeutic combination for GVHD refractory to steroids and cyclosporine.

Granulocyte-colony-stimulating factor (G-CSF)-primed allogeneic bone marrow: significantly less graft-versus-host disease and comparable engraftment to G-CSF-mobilized peripheral blood stem cells

Prospective studies have shown rapid engraftment using granulocyte-colony-stimulating factor-mobilized peripheral blood stem cells (G-PBSCs) for allogeneic transplantation, though the risks for graft-versus-host disease (GVHD) may be increased. It was hypothesized that the use of G-CSF to prime bone marrow (GBM) would allow rapid engraftment without increased risk for GVHD compared with G-PBSC. Patients were randomized to receive G-BM or G-PBSCs for allogeneic stem cell transplantation. The study was designed (beta < .8) to detect a difference in the incidence of chronic GVHD of 33% ( < .05). The plan was to recruit 100 patients and to conduct an interim analysis when the 6-month follow-up point was reached for the first 50 patients. Fifty-seven consecutive patients were recruited (G-BM, n = 28; G-PBSC, n = 29). Patients in the G-PBSC group received 3-fold more CD34(+) and 9-fold more CD3(+) cells. Median times to neutrophil (G-BM, 16 days; G-PBSC, 14 days; P < .1) and platelet engraftment (G-BM, 14 days; G-PBSC, 12 days; P < .1) were similar. The use of G-PBSC was associated with steroid refractory acute GVHD (G-BM, 0%; G-PBSC, 32%; P < .001), chronic GVHD (G-BM, 22%; G-PBSC, 80%; P < .02), and prolonged requirement for immunosuppressive therapy (G-BM, 173 days; G-PBSC, 680 days; P < .009). Survival was similar for the 2 groups. Compared with G-PBSC the use of G-BM resulted in comparable engraftment, reduced severity of acute GVHD, and less subsequent chronic GVHD. (Blood. 2001;98:3186-3191) (C) 2001 by The American Society of Hematology.

What's new in hemochromatosis

Hereditary hemochromatosis (HHC) is an inherited disorder of iron metabolism affecting approximately 1 in 200-300 individuals of Northern European descent. Over time, the continued deposition of iron in parenchymal cells of many organs can eventually lead to diabetes mellitus, cardiomyopathy, and hepatic cirrhosis, the last of which is frequently followed by hepatocellular carcinoma. Although the complications of HHC can be devastating, its clinical management is simple and effective if the disease is identified early in its progression. The recent elucidation of the HFE gene has provided insight into the pathogenesis of HHC and provided a means for the early identification of individuals in whom HHC may develop. Two mutations have been implicated in HHC: C282Y and H63D, The former occurs in a homozygous state seen in 75-100% of patients with HHC. The high correlation of HFE to HHC has caused it to be considered as a candidate gene for population-based genetic testing for diagnosis and detection of predisposition to HHC. In addition, mechanisms of iron transport and metabolism are unfolding and are providing clues to the enigma of iron homeostasis and the pathophysiology of iron overload, (C) 2001 Lippincott Williams & Wilkins, Inc.

Foraging by the endangered black-breasted button-quail (Turnix melanogaster) within fragmented rainforest of an agricultural landscape

We studied the foraging habitat of the endangered black-breasted button-quail (Turnix melanogaster) in 13 rainforest patches of an agricultural landscape (23.4 km(2)) in eastern Australia to assess its use of fragmented habitats outside conservation reserves. The species foraged only in the three largest patches (17.4, 40.0, 63.8 ha in size), all of which were connected to open eucalypt forest, and in intact rainforest. Occurrence of birds was greatest in the largest patch. The maximum number of individuals within the study area was estimated to be 22. Radio-tracking of nine birds revealed that three were resident in the largest patch for periods of over 100 days; no movements between patches were detected. Three radio-tagged birds were taken by avian and mammalian predators. Our results indicated that the long-term future of the species in agricultural landscapes is bleak and that management action is urgently needed to arrest its decline in these ecosystems, (C) 2001 Elsevier Science Ltd. All rights reserved.

TRAIL expression by activated human CD4(+)V alpha 24NKT cells induces in vitro and in vivo apoptosis of human acute myeloid leukema cells

Human V alpha 24NKT cells are activated by alpha -galactosylceramide (alpha -GalCer)-pulsed dendritic cells in a CD1d-dependent and a T-cell receptor-mediated manner. Here, we demonstrate that CD4(+)V alpha 24NKT cells derived from a patient with acute myeloid leukemia (AML) M4 are phenotypically similar to those of healthy donors and, in common with those derived from healthy donors, express tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) when the cells are activated by alpha -GalCer-pulsed dendritic cells but not prior to activation. We also show that myeloid that human activated CD4(+)V alpha 24NKT cells induced apoptosis of human leukemia cells in vivo. This is the first evidence that activated V alpha 24NKT cells express TRAIL and that TRAIL causes apoptosis of monocytic leukemia cells from patients with AML M4 in vitro and in vivo. Adoptive immune therapy with activated V alpha 24NKT cells, or other strategies to increase activated V alpha 24NKT cells in vivo, may be of benefit to patients with AML M4.

HIV gp120 receptors on human dendritic cells

Dendritic cells (DCs) are important targets for human immunodeficiency virus (HIV) because of their roles during transmission and also maintenance of immune competence. Furthermore, DCs are a key cell in the development of HIV vaccines. In both these settings the mechanism of binding of the HIV envelope protein gp120 to DCs is of importance. Recently a single C-type lectin receptor (CLR), DC-SIGN, has been reported to be the predominant receptor on monocyte-derived DCs (MD-DCs) rather than CD4. In this study a novel biotinylated gp120 assay was used to determine whether CLR or CD4 were predominant receptors on MDDCs and ex vivo blood DCs. CLR bound more than 80% of gp120 on MDDCs, with residual binding attributable to CD4, reconfirming that CLRs were the major receptors for gp120 on MDDCs. However, in contrast to recent reports, gp120 binding to at least 3 CLRs was observed: DC-SIGN, mannose receptor, and unidentified trypsin resistant CLR(s). In marked contrast, freshly isolated and cultured CD11c(+ve) and CD11c(-ve) blood DCs only bound gp120 via CD4. In view of these marked differences between MDDCs and blood DCs, HIV capture by DCs and transfer mechanisms to T cells as well as potential antigenic processing pathways will need to be determined for each DC phenotype. (Blood. 2001;98:2482-2488) (C) 2001 by The American Society of Hematology.

A highly conserved c-fms gene intronic element controls macrophage-specific and regulated expression

The c fins gene encodes the receptor for macrophage colony-stimulating factor-1. This gene is expressed selectively in the macrophage cell lineage. Previous studies have implicated sequences in intron 2 that control transcript elongation in tissue-specific and regulated expression of c -fms. Four macrophage-specific deoxyribonuclease I (DNase I)-hypersensitive sites (DHSS) were identified within mouse intron 2. Sequences of these DHSS were found to be highly conserved compared with those in the human gene. A 250-bp region we refer to as the fins intronic regulatory element (FIRE), which is even more highly conserved than the c-fins proximal promoter, contains many consensus binding sites for macrophage-expressed transcription factors including Spl, PU.1, and C/EBP. FIRE was found to act as a macrophage-specific enhancer and as a promoter with an antisense orientation preference in transient transfections. In stable transfections of the macrophage line RAW264, as well as in clones selected for high and low-level c -fms mRNA expression, the presence of intron 2 increased the frequency and level of expression of reporter genes compared with those attained using the promoter alone. Removal of FIRE abolished reporter gene expression, revealing a suppressive activity in the remaining intronic sequences. Hence, FIRE is shown to be a key regulatory element in the fins gene.

Functional heterogeneity within rhodamine123(lo) Hoechst33342(lo/sp) primitive hemopoietic stem cells revealed by pyronin Y

Objective. The aim of this study was to determine the function of primitive hematopoietic stem cells (PHSC) at phases G(0) and G(1) of the cell cycle. Materials and Methods. A combination of supravital dyes rhodamine123 (Rh), Hoechst33342 (Ho), and pyronin (PY) was used to isolate the G(0) and G(1) subsets of PHSC. A competitive repopulation assay was used to evaluate their in vivo function. Results. We confirmed that the Rh(lo)Lin(-)Kit(+)Sca-1(+) PHSC were relatively quiescent when compared with the more mature Rh(hi)Lin(-)Kit(+)Sca-1 HSC and Rh(hi)Lin(-)Kit(+)Sca-1(-) progenitors. In addition, cells with Rh(lo)Lin(-)Kit(+)Sca-1(+), Rh(lo)Ho(lo)Lin(-)Sca-1(+), or Rh(lo)Ho(sp)Lin(-)Sca-1(+) phenotypes identified the same cell population. We further subfractionated the Rh(lo)Ho(lo/sp)Lin(-)Sca-1(+) PHSC using PY into PYlo and PYhi subsets. Limiting dilution analysis revealed that the frequency of long-term in vivo competitive repopulating units (CRU) of the (PYRhHolo/sp)-Rh-lo-Ho-lo PHSC was 1 in 10 cells, whereas there was at least a three-fold lower frequency in those isolated at the G(1) phase (PYhi) We found a dose-dependent PY-mediated cytotoxicity that at moderate concentration affected most of the murine hematopoietic compartment but spared the early HSC compartment. Conclusion. Our data confirm that the HSC compartment is hierarchically ordered on the basis of quiescence and further extend this concept to PY-mediated cytotoxicity. PY supravital dye can be used to reveal functional heterogeneity within the (RhHolosp)-Ho-lo PHSC population but is of limited use in dissecting the relatively more mature hematopoietic stem/progenitor cell population. (C) 2001 International Society for Experimental Hematology. Published by Elsevier Science Inc.

Microevolution in island forms: the roles of drift and directional selection in morphological divergence of a passerine bird

Theory predicts that in small isolated populations random genetic drift can lead to phenotypic divergence; however this prediction has rarely been tested quantitatively in natural populations. Here we utilize natural repeated island colonization events by members of the avian species complex, Zosterops lateralis, to assess whether or not genetic drift alone is an adequate explanation for the observed patterns of microevolutionary divergence in morphology. Morphological and molecular genetic characteristics of island and mainland populations are compared to test three predictions of drift theory: (1) that the pattern of morphological change is idiosyncratic to each island; (2) that there is concordance between morphological and neutral genetic shifts across island populations; and (3) for populations whose time of colonization is known, that the rate of morphological change is sufficiently slow to be accounted for solely by genetic drift. Our results are not consistent with these predictions. First, the direction of size shifts was consistently towards larger size, suggesting the action of a nonrandom process. Second, patterns of morphological divergence among recently colonized populations showed little concordance with divergence in neutral genetic characters. Third, rate tests of morphological change showed that effective population sizes were not small enough for random processes alone to account for the magnitude of microevolutionary change. Altogether, these three lines of evidence suggest that drift alone is not an adequate explanation of morphological differentiation in recently colonized island Zosterops and therefore we suggest that the observed microevolutionary changes are largely a result of directional natural selection.