Comprehensive Chromosome End Remodeling during Programmed DNA Elimination.

Germline and somatic genomes are in general the same in a multicellular organism. However, programmed DNA elimination leads to a reduced somatic genome compared to germline cells. Previous work on the parasitic nematode Ascaris demonstrated that programmed DNA elimination encompasses high-fidelity chromosomal breaks and loss of specific genome sequences including a major tandem repeat of 120 bp and ~1,000 germline-expressed genes. However, the precise chromosomal locations of these repeats, breaks regions, and eliminated genes remained unknown. We used PacBio long-read sequencing and chromosome conformation capture (Hi-C) to obtain fully assembled chromosomes of Ascaris germline and somatic genomes, enabling a complete chromosomal view of DNA elimination. We found that all 24 germline chromosomes undergo comprehensive chromosome end remodeling with DNA breaks in their subtelomeric regions and loss of distal sequences including the telomeres at both chromosome ends. All new Ascaris somatic chromosome ends are recapped by de novo telomere healing. We provide an ultrastructural analysis of Ascaris DNA elimination and show that eliminated DNA is incorporated into double membrane-bound structures, similar to micronuclei, during telophase of a DNA elimination mitosis. These micronuclei undergo dynamic changes including loss of active histone marks and localize to the cytoplasm following daughter nuclei formation and cytokinesis where they form autophagosomes. Comparative analysis of nematode chromosomes suggests that chromosome fusions occurred, forming Ascaris sex chromosomes that become independent chromosomes following DNA elimination breaks in somatic cells. These studies provide the first chromosomal view and define novel features and functions of metazoan programmed DNA elimination.

Phenotypic and functional characteristics of HLA-DR+ neutrophils in Brazilians with cutaneous leishmaniasis.

The protozoan Leishmania braziliensis causes cutaneous leishmaniasis (CL) in endemic regions. In murine models, neutrophils (PMNs) are recruited to the site of infection soon after parasite inoculation. However, the roles of neutrophils during chronic infection and in human disease remain undefined. We hypothesized that neutrophils help maintain a systemic inflammatory state in subjects with CL. Lesion biopsies from all patients with CL tested contained neutrophils expressing HLA-DR, a molecule thought to be restricted to professional antigen-presenting cells. Although CL is a localized disease, a subset of patients with CL also had circulating neutrophils expressing HLA-DR and the costimulatory molecules CD80, CD86, and CD40. PMNs isolated from a low-density leukocyte blood fraction (LD-PMNs) contained a higher percentage of HLA-DR+ PMNs than did normal-density PMNs. In vitro coculture experiments suggested LD-PMNs do not suppress T cell responses, differentiating them from MDSCs. Flow-sorted HLA-DR+ PMNs morphologically resembled conventional PMNs, and they exhibited functional properties of PMNs. Compared with conventional PMNs, HLA-DR+ PMNs showed increased activation, degranulation, DHR123 oxidation, and phagocytic capacity. A few HLA-DR+ PMNs were observed in healthy subjects, and that proportion could be increased by incubation in either inflammatory cytokines or in plasma from a patient with CL. This was accompanied by an increase in PMN hladrb1 mRNA, suggesting a possible connection between neutrophil "priming" and up-regulation of HLA-DR. These data suggest that PMNs that are primed for activation and that also express surface markers of antigen-presenting cells emerge in the circulation and infected tissue lesions of patients with CL.

The crystalloid vs colloid controversy in the era os hypertonic/hyperoncotic resuscitations: is the debate over?

The crystalloid vs. colloid controversy has been further complicated by the inclusion of hypertonic levels of sodium chloride (HTS) in both types of regimens. In this paper the recent literature on the controversy is reviewed. Colloids raise the intravascular colloid osmotic pressure and increase the fluid retention in the vessels. Crystalloids however, distribute into the interstitial and intravascular spaces at a ratio of approximately 3 to 1. It is therefore necessary to infuse a large volume of crystalloids in order to complete resuscitation. The advantage of colloids over isotonic crystalloids focuses primarily on the incidence of pulmonary edema. In an analysis of clinical trials, however, colloids were not proven to be superior to crystalloids. The use of HTS decreases the amount of crystalloid required for resuscitation. Pulmonary and systemic vasodilation, an increase in cardiac output and stroke volume, decreased intracranial pressure and an enhanced immunologic response have been noted experimentally, and the clinical evidence seems to corroborate these findings. HTS with dextran (HSD) has been used in an attempt to combine the rapid cellular fluid shift of hypertonicity with the vascular fluid shift of colloids. The experimental evidence is compelling. Whereas HTS has proven itself to be a superior resuscitation regimen, HSD has not yet warranted in a clinical setting the optimism which its experimental studies seem to indicate.