Extended long-term culture reveals a highly quiescent and primitive human hematopoietic progenitor population

Long-term culture-initiating cells (LTC-IC) are hematopoietic progenitors able to generate colony-forming unit-cells (CFU) after 5 to 8 weeks (35 to 60 days) of culture on bone marrow (BM) stroma and represent the most primitive progenitors currently detectable in vitro. We have recently reported that long-term cultures initiated with CD34+CD38- cells from BM or cord blood are able to continue generating CFU for at least 100 days, ie, beyond the standard LTC-IC period. In this report, single-cell cultures from cord blood and retroviral marking of cord blood and BM were used to study whether the subpopulation of CD34+CD38- cells able to generate CFU beyond 60 days ("extended long-term culture-initiating cells" or ELTC-IC) are functionally distinct from LTC-IC in terms of timing of initial clonal proliferation and generative capacity. All cord blood LTC-IC formed clones of greater than 50 cells by day 30. In contrast, cord blood ELTC- IC proliferated later in culture, 50% forming clones after day 30. Although efficient retroviral marking of LTC-IC was seen (25% to 45%), marking of ELTC-IC was inefficient (< 1%), consistent with a more quiescent progenitor population. There was a positive correlation between time of clonal proliferation and generative capacity. ELTC-IC generated threefold to fourfold more progeny than did LTC-IC (P < .002). These studies show that there is a functional hierarchy of progenitors in long-term culture which correlates with their level of quiescence. By extending the LTC-IC assay, a more primitive progenitor may be studied that may be functionally closer to the human long-term repopulation stem cell in vivo.     

The spectrum of MR detectable cortical microinfarcts: a classification study with 7-tesla postmortem MRI and histopathology

Cerebral microinfarcts (CMIs) are common neuropathologic findings in aging and dementia. We explored the spectrum of cortical CMIs that can be visualized with 7T magnetic resonance imaging (MRI). Thirty-three coronal brain slices of 11 individuals with neuropathologically confirmed dementia were subjected to a high-resolution postmortem 7T MRI protocol. First, we identified all visible small (⩽5 mm) intracortical and juxtacortical lesions on postmortem MRI. Lesions were classified as CMI or nonCMI based on histology, and their MR features were recorded. Thirty lesions were identified on the initial MRI evaluation, of which twenty-three could be matched with histology. Histopathology classified 12 lesions as CMIs, all of which were located intracortically. On the basis of their MR features, they could be classified as chronic gliotic CMIs—with or without cavitation or hemorrhagic components—and acute CMIs. Eleven MRI identified lesions were not of ischemic nature and most commonly enlarged or atypically shaped perivascular spaces. Their MRI features were similar to gliotic CMIs with or without cavitation, but these ‘CMI mimics'' were always located juxtacortically. 7T postmortem MRI distinguishes different histopathologic types of cortical CMIs, with distinctive MR characteristics. On the basis of our findings, we propose in vivo rating criteria for the detection of intracortical CMIs.     

TRPC6 channel translocation into phagosomal membrane augments phagosomal function

Defects in the innate immune system in the lung with attendant bacterial infections contribute to lung tissue damage, respiratory insufficiency, and ultimately death in the pathogenesis of cystic fibrosis (CF). Professional phagocytes, including alveolar macrophages (AMs), have specialized pathways that ensure efficient killing of pathogens in phagosomes. Phagosomal acidification facilitates the optimal functioning of degradative enzymes, ultimately contributing to bacterial killing. Generation of low organellar pH is primarily driven by the V-ATPases, proton pumps that use cytoplasmic ATP to load H⁺ into the organelle. Critical to phagosomal acidification are various channels derived from the plasma membrane, including the anion channel cystic fibrosis transmembrane conductance regulator, which shunt the transmembrane potential generated by movement of protons. Here we show that the transient receptor potential canonical-6 (TRPC6) calcium-permeable channel in the AM also functions to shunt the transmembrane potential generated by proton pumping and is capable of restoring microbicidal function to compromised AMs in CF and enhancement of function in non-CF cells. TRPC6 channel activity is enhanced via translocation to the cell surface (and then ultimately to the phagosome during phagocytosis) in response to G-protein signaling activated by the small molecule (R)-roscovitine and its derivatives. These data show that enhancing vesicular insertion of the TRPC6 channel to the plasma membrane may represent a general mechanism for restoring phagosome activity in conditions, where it is lost or impaired.Chronic infection and inflammation in the airways in cystic fibrosis (CF), as well as chronic obstructive pulmonary disease (COPD), tuberculosis, and asthma are now among the most common chronic diseases. Pulmonary infection associated with these diseases has historically been treated with antibiotics that kill bacteria but also select for development of resistance in the pathogen in the chronically infected lung (1, 2). One solution to antimicrobial drug resistance is to target the host rather than the pathogen. This strategy necessitates finding alternative targets or signaling strategies amplifying or restoring bactericidal capacity in the cells charged with the task of resolving chronic infection.Mononuclear phagocytes orchestrate the innate immune response in the lung through the combinatorial interplay between the phagocytic uptake and killing of bacterial invaders, clearance of apoptotic cells, antigen presentation, and secretion of vesicle-bound signaling molecules to recruit help in the resolution of infection. Ionic fluxes across the phagosomal membrane that encloses the pathogen produce a hostile acidic environment developed through the action of a V-ATPase proton translocation. However, a positive intraphagosomal membrane potential generated by proton translocation minimizes the proton content of the phagosome. An influx of Cl⁻ via Cl⁻ channels reduces the membrane potential generated by the proton pump, thereby, allowing maximal acidification of the phagolysosomal compartment, which in turn maximizes the activation of lysosomal degradative enzymes, generation of hypochlorous acid, and consequent bacterial killing (3, 4). We have previously demonstrated that murine alveolar macrophages (AMs) use the anion channel cystic fibrosis transmembrane conductance regulator (CFTR) as a Cl⁻ permeation pathway in the phagosomal membrane. In CF, loss of functional CFTR in the AM alkalinizes the phagosomal lumen and allows antimicrobial-resistant bacterial pathogens to survive macrophage surveillance.Not all tissue macrophages use CFTR as a charge compensation pathway in phagolysosomal acidification (4). In fact, recent data suggest that multiple V-ATPase charge-shunt pathways can exist in diverse macrophage lineages (5) via lysosomal recruitment and membrane insertion upon particle uptake. This observation led us to search for possible alternative charge-shunt pathways in pulmonary macrophages and how they might be activated or targeted to the maturing phagosome. Could a pharmacological tool circumvent the defect in CF AMs and activate alternative pathways to rescue both organellar acidification and bactericidal activity in cells expressing mutations in CFTR? Such a tool might activate parallel charge-shunt pathways used in peritoneal macrophages for maximum acidification, thereby allowing them to clear bacteria independently of CFTR expression as well as amplify the microbicidal response in the presence of functional CFTR. The transport proteins and channels active in peritoneal macrophage bacterial clearance have not been described but may involve a K⁺/H⁺ exchanger important in promoting excitatory synaptic vesicle filling (6) or a cation channel moving positive charge out of the phagolysosomal compartment, as has been suggested for macrophage cell lines (7).We began our investigations pursuing a novel pharmacological strategy to identify compounds that would resolve bacterial infection in the CF lung without the use of antimicrobials. We picked a cellular defect in CF because of the availability of animal models and extended our observations to non-CF human pulmonary cells. We designed screening assays of phagosome function, which could be used in a clinical setting as both diagnostic and investigational tools. We interrogated host function by studying surface receptor-mediated mechanisms that might provide parallel signaling pathways in subcellular organellar function in the resolution of disease.We report that a series of small molecules first identified in chemotherapeutics, (R)-roscovitine [2-(R)-(1-ethyl-2-hydroxyethylamino)-6-benzylamino-9-isopropylpurine] and its derivatives, restore microbicidal function to compromised AMs in CF and enhance function in non-CF cells. The compounds use a G protein-mediated signaling pathway, which results in the mobilization of transient receptor potential canonical-6 (TRPC6) calcium-permeable, nonselective cation channels to the plasma membrane and subsequently to the phagosomal membrane. Members of the TRP channel family have been implicated in a number of critical phagocytic functions, including particle uptake, migration, and reactive oxygen species (ROS) production (5, 8–11). Numerous studies (12–15) have suggested TRP channels as potential targets for the development of therapies in pulmonary inflammation because of their abundant and diverse cellular expression throughout the respiratory tree. Although TRPC6 channels have been previously identified in lung macrophages and shown to be up-regulated in COPD, their precise role in the pathophysiology of the disease is yet to be determined (16). Perhaps more relevant to our study, a TRPC6-mediated Ca²⁺ influx is increased in human CF airway epithelial cells, possibly because of a functional association between CFTR and TRPC6 that is lost in CF (17), with unknown consequences. To our knowledge, this study is the first to associate TRPC6 channels a specific drug-targeting strategy for the resolution chronic pulmonary infection.     

二尖瓣疾病左心室充盈压的多普勒评估

由于在瓣膜区域、左心室松弛性和僵直性等方面易于发生混淆．传统多普勒测量对二尖瓣疾病病人左心房压的预测上受到限制。然而，在犬和临床研究中，组织多普勒成像所测定的充盈早期二尖瓣血流速率起始段和房室环的充盈早期速率之间的时间窗（time interval between the onset of early diastolic mitral inflow velocity and annular early diastolic velocity，TE-Ea）与左心室舒张时间常数（time constant of left ventricular relaxation，t）良好相关，并且不受上述瓣膜区域、左心室舒张和僵直等变量的影响。因此在病人人群中开展这项研究，检验其用途。     

The significance of HLA-DRB1 matching on clinical outcome after HLA-A, B, DR identical unrelated donor marrow transplantation

Despite matching for serologically defined HLA-A, B, DR antigens, acute graft-versus-host disease (GVHD) is a major complication contributing to increased morbidity and mortality in patients who undergo marrow transplantation from unrelated donors. The extent to which unrecognized mismatching for alleles that encode DR1-DR18 contribute to the increased risk of acute GVHD and overall survival is unknown. We analyzed 364 patients and their HLA-A, B, DR serologically matched donors to determine whether molecular typing of DRB1 alleles can allow more accurate donor/recipient matching and thereby improve clinical outcome after marrow transplantation. DRB1 alleles were typed by sequence-specific oligonucleotide probe hybridization methods. Selected alleles were confirmed by DNA sequencing. Of the 364 pairs, 305 were matched and 59 were mismatched for DRB1. The probability of moderate to severe acute GVHD was .48 for the matched and .70 for the mismatched patients. Compared with mismatched patients, the estimated relative risk (RR) of GVHD for matched patients was .58 (95% confidence interval [CI], .40 to .85). DRB1 matching decreased the risk of transplant- related mortality (RR, .66; 95% CI, .44 to .97) and was associated with decreased overall mortality (RR, .71; 95% CI, .51 to 1.0). Therefore, matching DRB1 alleles of the donor and recipient decreases the risk of acute GVHD and improves survival after unrelated marrow transplantation. These results indicate that prospective matching of patients and donors for DRB1 alleles is warranted.     

Detection of platelet-directed immunoglobin G in sera using the peroxidase-anti-peroxidase (PAP) slide technique

An immunohistochemical procedure for the detection of immunoglobulin G adherent to platelets is described. The peroxidase anti-peroxidase method is used to detect antibody activity directed against platelets from normal donors in the sera from 305 individuals. These subjects were divided into three groups: group 1, patients referred for tissue typing; group 2, healthy normal females; group 3, healthy normal males. In group 1, 28% of the sera were found to be positive; in most of these a history of prior transfusions was obtained. In group 2, 7.4% were found to be positive, most having previous pregnancies. Only 1% were found to be positive in group 3, and no reason for presensitization was found. Results from the indirect immunofluorescence technique served as a control and as a means to compare the sensitivity. Under the conditions chosen, the peroxidase anti-peroxidase test was two to eight times more sensitive than the immunofluorescence technique. Specificity of the peroxidase anti-peroxidase technique was demonstrated using a monospecific anti-PLA1 antiserum. It is concluded that the peroxidase anti-peroxidase slide technique may be a useful tool in the study of platelet-related immunophenomena.     

Human platelets exert cytotoxic effects on tumor cells

Monocytes are thought to play a role in host resistance to tumor cell growth in animals and humans. In addition, platelets are known to be involved in tumor metastases. To investigate the interaction of these two cell types and their effect on tumor cells, human monocytes and platelets were examined using an in vitro monocyte-tumor cell cytotoxicity assay. Monocytes alone resulted in 32% +/- 1.5 (mean +/- SEM) tumor cell kill. When platelets were added to monocytes in a 1:1 ratio, an increase in cytotoxicity to 61% +/- 3.2 was observed. The cytotoxicity noted when platelets were added to a fixed number of monocytes and tumor cells was dependent on the number of platelets added. A decrease in cytotoxicity from 32% +/- 1.5 to 12% +/- 2.3 was observed when contaminating platelets were removed from monocyte preparations. Platelets added to tumor cells in the absence of any monocytes were also toxic, resulting in a maximum kill of 95% at a 4:1 platelet/tumor cell ratio. Secreted products of freshly isolated platelets may be responsible for much of the observed cytotoxicity, since supernatants from the platelets were toxic for tumor cells. Platelets pretreated with a cyclooxygenase inhibitor (ASA) or a lipoxygenase inhibitor had decreased cytotoxicity compared with untreated platelets. Our results indicate that products of platelet arachidonate metabolism are toxic for tumor cell lines. They also suggest that the role of the platelet must be considered when studying monocyte-tumor cell cytotoxicity.     

Elevated NAD(P) glycohydrolase activity: a possible enzymatic marker for malignancy in Burkitt's lymphoma cells

A comparative analysis of enzymatic activities has been performed on 47 human continuous lymphoid lines: 22 tumors derived from Burkitt's lymphoma lines, 6 other lymphomatous long-term cultures, and 19 nonmalignant ties determined on the cell extracts. 4 showed no significant differences between the various lines. They included adenosine diphosphoribose incorporation, glucose-6-phosphate dehydrogenase, cyclic-AMP phosphodiesterase, and glutathione reductase. However, striking differences of activity were found for the enzyme, NAD(P) glycohydrolase (EC 3.2.2.6). Activity levels were, as a mean, four times higher in Burkitt's lymphoma-derived cell lines than in nonmalignant control lines, and the difference was highly significant (p less than 0.02). All Burkitt cell lines containing translocations of chromosome 8 with either chromosomes 2, 14 or 22 showed an increased activity. The specificity and significance of this possible enzymatic marker of Burkitt's lymphoma cells is discussed.     

Bone marrow transplantation for patients with Philadelphia chromosome- positive acute lymphoblastic leukemia

We report the treatment outcome of allogeneic bone marrow transplantation in ten patients with Philadelphia chromosome-positive acute lymphoblastic leukemia. Six patients are alive and well for 6 to 30 months (median 19 months) after transplantation. Four patients died with transplant related complications. In view of the poor prognosis associated with this disease, marrow ablation followed by allogeneic or syngeneic marrow grafting may be the preferred treatment modality if a suitable marrow donor is available.