The pathophysiology of pure red cell aplasia: implications for therapy

To determine the utility of marrow culture in defining the natural history and therapeutic response of pure red cell aplasia we have studied 37 patients. Patients were evaluated at the University of Washington before specific therapies (n = 21) or at the time of treatment failure in = 16). Evaluation included a medical and drug exposure history, a physical examination, a chest x-ray or computed tomography to rule out thymoma, lymphocyte immunophenotype studies, anti-nuclear antibody and rheumatoid factor determinations, marrow cytogenetics, and marrow progenitor cell cultures. Retrospective Southern analyses to detect human parvovirus B19 was performed in the 27 patients for whom sera was stored. Clinical follow-up was obtained to document therapeutic responses. Normal burst forming unit-erythroid (BFU-E) growth (>30 bursts/10(5) marrow mononuclear cells [MMNC]) in culture proved an outstanding predictor of clinical response, as 27 of 29 individuals with normal frequencies of erythroid bursts in culture responded to immunomodulating therapies (sensitivity 96%, specificity 78%, predictive value 93%, P = .0001 with two-tailed chi square analysis). Overall, 28 patients responded to either immunomodulating therapies or drug withdrawal. Twenty-four patients obtained a normal hematocrit (complete response [CR] and 4 additional patients became transfusion independent (partial response). Although responding patients often required several therapies, 20 of 24 (83%) patients who obtained a CR have sustained a normal hematocrit without maintenance therapy at the time of last follow-up (median 5 years). In contrast, of 8 patients with poor in vitro BFU-E growth (<6 bursts/10(5) MMNC), 7 failed to respond to any therapy and all died (median survival time 17 months). Our data suggest that in individuals, from whom BFU-E mature appropriately in culture, immunosuppressive drugs should be used sequentially until a CR is obtained and a durable remission is the expected outcome.     

Outcome of unrelated donor bone marrow transplantation in 40 children with Hurler syndrome

Long-term survival and improved neuropsychological function have occurred in selected children with Hurler syndrome (MPS I H) after successful engraftment with genotypically matched sibling bons marrow transplantation (BMT). However, because few children have HLA-identical siblings, the feasibility of unrelated donor (URD) BMT as a vehicle for adoptive enzyme therapy was evaluated in this retrospective study. Forty consecutive children (median, 1.7 years; range, 0.9 to 3.2 years) with MPS I H received high-dose chemotherapy with or without radiation followed by BMT between January 27, 1989 and May 13, 1994. Twenty-five of the 40 patients initially engrafted. An estimated 49% of patients are alive at 2 years, 63% alloengrafted and 37% autoengrafted. The probability of grade II to IV acute graft-versus-host disease (GVHD) was 30%, and the probability of extensive chronic GVHD was 18%. Eleven patients received a second URD BMT because of graft rejection or failure. Of the 20 survivors, 13 children have complete donor engraftment, two children have mixed chimeric grafts, and five children have autologous marrow recovery. The BM cell dose was correlated with both donor engraftment and survival. Thirteen of 27 evaluable patients were engrafted at 1 year following URD BMT. Neither T-lymphocyte depletion (TLD) of the bone marrow nor irradiation appeared to influence the likelihood of engraftment. Ten of 16 patients alive at 1 year who received a BM cell dose greater than or equal to 3.5 x 10(8) cells/kg engrafted, and 62% are estimated to be alive at 3 years. In contrast, only 3 of 11 patients receiving less than 3.5 x 10(8) cells/kg engrafted, and 24% are estimated to be alive at 3 years (P = .05). The mental developmental index (MDI) was assessed before BMT. Both baseline and post-BMT neuropsychological data were available for 11 engrafted survivors. Eight children with a baseline MDI greater than 70 have undergone URD BMT (median age, 1.5 years; range, 1.0 to 2.4 years). Of these, two children have had BMT too recently for developmental follow-up. Of the remaining six, none has shown any decline in age equivalent scores. Four children are acquiring skills at a pace equal to or slightly below their same age peers; two children have shown a plateau in learning or extreme slowing in their learning process. For children with a baseline MDI less than 70 (median age, 2.5 years; range, 0.9 to 2.9 years), post-BMT follow-up indicated that two children have shown deterioration in their developmental skills. The remaining three children are maintaining their skills and are adding to them at a highly variable rate. We conclude that MPS I H patients with a baseline MDI greater than 70 who are engrafted survivors following URD BMT can achieve a favorable long-term outcome and improved cognitive function. Future protocols must address the high risk of graft rejection or failure and the impact of GVHD in this patient population.     

口服蒿甲醚控制重疫区血吸虫病及预防急性感染

目的观察口服蒿甲醚控制日本血吸虫病重疫区人群感染及预防急性感染的效果.方法在鄱阳湖区血吸虫病易感季节(5～10月)对重疫区村居民采用15 d间隔口服蒿甲醚预防感染.同时设对照组,口服安慰剂.结果感染季节结束后,实验组人群粪检阳性率为0.83%,无急性感染发生;对照组粪检阳性率为15.01%,发生3例急性感染.结论每15天间隔口服蒿甲醚1次,对重疫区人群有良好的保护作用,保护率为94.47%,有利于控制人群感染;对防止急性感染也有明显效果.     

Tempo and mode of regulatory evolution in Drosophila

Genetic changes affecting gene expression contribute to phenotypic divergence; thus, understanding how regulatory networks controlling gene expression change over time is critical for understanding evolution. Prior studies of expression differences within and between species have identified properties of regulatory divergence, but technical and biological differences among these studies make it difficult to assess the generality of these properties or to understand how regulatory changes accumulate with divergence time. Here, we address these issues by comparing gene expression among strains and species of Drosophila with a range of divergence times and use F₁ hybrids to examine inheritance patterns and disentangle cis- and trans-regulatory changes. We find that the fixation of compensatory changes has caused the regulation of gene expression to diverge more rapidly than gene expression itself. Specifically, we observed that the proportion of genes with evidence of cis-regulatory divergence has increased more rapidly with divergence time than the proportion of genes with evidence of expression differences. Surprisingly, the amount of expression divergence explained by cis-regulatory changes did not increase steadily with divergence time, as was previously proposed. Rather, one species (Drosophila sechellia) showed an excess of cis-regulatory divergence that we argue most likely resulted from positive selection in this lineage. Taken together, this work reveals not only the rate at which gene expression evolves, but also the molecular and evolutionary mechanisms responsible for this evolution.Understanding the relationship between tempo (the rate at which a trait evolves) and mode (the manner in which a trait evolves) is essential for understanding the evolutionary process (Simpson 1944). This is true not only for organismal phenotypes, but also for the molecular phenotypes that produce organismal traits. Gene expression is one such molecular phenotype (Gordon and Ruvinsky 2012); it is essential for organismal form, fitness, and function, and frequently varies within and between species. Comparative studies using genomic surveys of gene expression in yeast (Busby et al. 2011), Drosophila (Rifkin et al. 2003), and mammalian species (Brawand et al. 2011) with a range of divergence times have provided insight into the tempo of gene expression evolution, but the mode and its relationship to tempo remain less well understood.Elucidating the mode of gene expression evolution includes identifying the types of regulatory changes that have evolved as well as how interactions among divergent regulatory alleles affect gene expression. F₁ hybrids, in which divergent regulatory alleles interact in the same cellular environment, can be used to investigate these issues. Allele-specific expression in F₁ hybrids separates the effects of cis- and trans-regulatory changes affecting a gene’s expression by providing a readout of relative cis-regulatory activity in a common trans-regulatory environment (Cowles et al. 2002). Expression differences between genotypes not attributed to cis-regulatory changes are inferred to be caused by trans-regulatory divergence (Wittkopp et al. 2004). In addition, the net effects of interactions among divergent regulatory alleles are revealed by comparing levels of total expression in F₁ hybrids to parental genotypes.This approach was initially used to separate cis- and trans-regulatory effects of divergence affecting expression of dozens of genes. These studies suggested that (1) cis-regulatory changes are more common than trans-regulatory changes between species (Wittkopp et al. 2004); (2) genes with cis- and trans-acting changes favoring expression of opposite alleles are more likely than other types of changes to cause misexpression in F₁ hybrids (Landry et al. 2005); (3) environmental factors modulate relative cis-regulatory activity (de Meaux et al. 2006); (4) cis-regulatory variation is abundant in natural populations (Osada et al. 2006; Genissel et al. 2007; Campbell et al. 2008; Gruber and Long 2009); and (5) the amount of expression divergence attributable to cis-acting changes is greater between than within species (Wittkopp et al. 2008).More recently, microarrays and RNA-seq have been used to extend these analyses to the genomic scale (Wang et al. 2008; Graze et al. 2009; Tirosh et al. 2009; Zhang and Borevitz 2009; Fontanillas et al. 2010; McManus et al. 2010; He et al. 2012; Shi et al. 2012; Coolon and Wittkopp 2013; Levy et al. 2013; Schaefke et al. 2013). In some cases, relationships seen in the smaller scale studies were replicated. For example, cis- and trans-regulatory changes with effects in opposite directions were overrepresented among misexpressed genes (Tirosh et al. 2009; McManus et al. 2010; Schaefke et al. 2013) and cis-regulatory changes explained more of the expression differences between than within species (Tirosh et al. 2009; Emerson et al. 2010). Other observations, such as the relative proportion of genes with evidence of cis- and/or trans-regulatory changes, were much more variable among studies. Finally, novel patterns, such as the relationship between dominance and cis/trans-regulatory changes (Lemos et al. 2008; McManus et al. 2010) and the frequency of compensatory cis- and trans-regulatory variants (Tirosh et al. 2009; Goncalves et al. 2012; Shi et al. 2012), were identified.Despite this growing collection of case studies examining the types of changes responsible for expression differences within and/or between particular pairs of species, the use of different organisms (flies, yeast, plants, and mice), techniques (pyrosequencing, microarrays, RNA-seq), and analysis methods (linear models, exact tests, and Bayesian approaches) among these studies precludes the type of meta-analysis needed to determine how the mode of regulatory evolution changes with divergence time and to robustly assess the generality of relationships reported in previous studies. To address these issues, we examined the tempo and mode of regulatory evolution in concert using strains and species of Drosophila with a range of divergence times.