Maintaining dendritic cell viability in culture

When mouse dendritic cells (DCs) are isolated from tissues, purified and placed in a nutritive culture they die more rapidly than would be expected from their normal turnover in vivo. This can distort culture assays of DC function. We therefore tested several approaches to prolonging DC survival in culture. Of several cytokines tested granulocyte-macrophage colony stimulating factor was most effective at preserving the viability of conventional DCs (cDCs) but was ineffective for plasmacytoid DCs (pDCs). Surprisingly, Fms-like tyrosine kinase 3 ligand, crucial for DC development, produced only a marginal improvement in DC survival in culture, and interleukin-3, reported to prevent apoptosis of human pDCs, produced only a minor improvement in survival of mouse DCs. Genetic manipulation of cell death pathways was also tested, to avoid activation effects exerted by cytokine signalling. The isolation of DCs from mice overexpressing Bcl-2 was especially effective in maintaining pDC viability but gave a lesser improvement in cDC viability. DCs isolated from Bim^−/−Noxa^−/− mice also showed improved culture survival, but in this case with pDCs showing the least improvement.     

Racial differences in effectiveness of alpha-fetoprotein for diagnosis of hepatocellular carcinoma in hepatitis C virus cirrhosis

alpha-Fetoprotein (AFP) is frequently used as a diagnostic marker for hepatocellular carcinoma (HCC). Most available data concerning AFP come from studies of patients with chronic hepatitis B or other chronic liver diseases of mixed etiologies. Limited data concerning the diagnostic value of AFP for hepatitis C virus (HCV)-related HCC have to date come only from Asian and European studies, and results are conflicting. There may be significant differences in AFP levels depending on racial backgrounds and etiologies of primary liver disease. We conducted a multicenter, retrospective, case-control study of 163 HCC patients with HCV infection and 149 control patients with HCV-related cirrhosis. The positive likelihood ratios for AFP at 0 to 20, 21 to 50, 51 to 100, and 101 to 200 ng/mL were 0.46, 1.31, 1.15, and 6.90, respectively. No controls had AFP greater than 200 ng/mL. The sensitivity of AFP for the diagnosis of HCC in African Americans with HCV infection was lower than that of patients of all other ethnic groups combined (57.1% vs. 81.6% for AFP > 10 ng/mL, P =.02, and 42.9% vs. 66.0% for AFP > 20 ng/mL, P =.05). The area under the receiver operating characteristics curve was 0.81 for non-African Americans but only 0.56 for African Americans. In conclusion, AFP greater than 200 ng/mL can be used to confirm HCC in patients with HCV-related cirrhosis and a hepatic mass. However, AFP is insensitive for the diagnosis of HCC in African Americans.     

Binding and recognition in the assembly of an active BRCA1/BARD1 ubiquitin-ligase complex

BRCA1 is a breast and ovarian cancer tumor suppressor protein that associates with BARD1 to form a RINGRING heterodimer. The BRCA1BARD1 RING complex functions as an ubiquitin (Ub) ligase with activity substantially greater than individual BRCA1 or BARD1 subunits. By using NMR spectroscopy and site-directed mutagenesis, we have mapped the binding site on the BRCA1BARD1 heterodimer for the Ub-conjugating enzyme UbcH5c. The results demonstrate that UbcH5c binds only to the BRCA1 RING domain and not the BARD1 RING. The binding interface is formed by the first and second Zn(2+)-loops and central alpha-helix of the BRCA1 RING domain, a region disrupted by cancer-predisposing mutations. Unexpectedly, a second Ub-conjugating enzyme, UbcH7, also interacts with the BRCA1BARD1 complex with similar affinity, although it is not active in Ub-ligase activity assays. Thus, binding alone is not sufficient for BRCA1-dependent Ub-ligase activity.     

hnRNP U protein is required for normal pre-mRNA splicing and postnatal heart development and function

We report that mice lacking the heterogeneous nuclear ribonucleoprotein U (hnRNP U) in the heart develop lethal dilated cardiomyopathy and display numerous defects in cardiac pre-mRNA splicing. Mutant hearts have disorganized cardiomyocytes, impaired contractility, and abnormal excitation–contraction coupling activities. RNA-seq analyses of Hnrnpu mutant hearts revealed extensive defects in alternative splicing of pre-mRNAs encoding proteins known to be critical for normal heart development and function, including Titin and calcium/calmodulin-dependent protein kinase II delta (Camk2d). Loss of hnRNP U expression in cardiomyocytes also leads to aberrant splicing of the pre-mRNA encoding the excitation–contraction coupling component Junctin. We found that the protein product of an alternatively spliced Junctin isoform is N-glycosylated at a specific asparagine site that is required for interactions with specific protein partners. Our findings provide conclusive evidence for the essential role of hnRNP U in heart development and function and in the regulation of alternative splicing.The expression of more than 95% of human genes is affected by alternative pre-mRNA splicing (AS) (1, 2). Differentially spliced isoforms play distinct roles in a temporally and spatially specific manner (3), and mutations that lead to aberrant splicing are the cause of many human genetic diseases (4). RNA-binding proteins (RBPs) play a central role in the regulation of alternative splicing during development and disease. They function primarily by positively or negatively regulating splice-site recognition by the spliceosome (1). Many RBPs are expressed in specific tissues, and AS is regulated by the combinatorial activities of these factors on specific pre-mRNAs through their interactions with distinct regulatory sequences in pre-mRNA that function as splicing enhancers or silencers (5).The developing heart is one of the best studied systems where splicing changes occur during normal development, and mutations affecting specific splicing outcomes contribute to cardiomyopathy (6, 7). Although these mutations can either disrupt splicing elements or affect the expression of specific splicing factors, the latter mechanism is clearly responsible for the distinct splicing profiles at different developmental stages. For example, the dynamics of alternative splicing during postnatal heart development correlate with expression changes of many RBPs, including CUG-BP, Elav-like family member 1 (CELF1), Muscleblind-like 1 (MBNL1), and FOX proteins (8). Detailed biochemical studies have elucidated the mechanisms by which these splicing factors regulate splicing in a position- and context-dependent manner (9, 10). The function of other RBPs during heart development has also been studied. For example, two of the muscle-specific splicing factors, RBM20 and RBM24, play distinct roles in splicing regulation. RBM20 mainly acts as a splicing repressor, as its absence leads to multiple exon inclusion events in the heart. For example, the Titin gene is one of the major targets of RBM20 (11, 12). On the other hand, loss of RBM24 expression gives rise to many exon skipping events (13), implicating RBM24 as a splicing activator. Strikingly, there is little overlap between RBM20 and RBM24 splicing targets, suggesting that RBM20 and RBM24 are involved in regulating splicing of distinct groups of pre-mRNAs and there is little cross-talk between these two splicing factors.Distinct splicing activities have also been ascribed to general splicing factors (1). There are two major types of ubiquitously expressed RBPs: the heterogeneous nuclear ribonucleoproteins (hnRNPs) and serine/arginine (SR)-rich proteins. hnRNPs and SR proteins are generally believed to play opposite roles in splicing: SR proteins promote the inclusion of exons during splicing, whereas hnRNP proteins repress inclusion (1). The function of certain SR proteins has been studied in the mouse heart through the conditional knockout approach. Srsf1 deletion in the heart leads to lethal dilated cardiomyopathy (DCM) (death occurs 6–8 wk after birth) (14). SRSF1 is required for the cardiac-specific splicing of Cypher (also called Ldb3) pre-mRNA, and the regulation of alternative splicing of calcium/calmodulin-dependent protein kinase II delta (Camk2d) and cardiac Troponin T (cTnT) during heart development. In particular, the persistent splicing of a neuronal isoform of Camk2d and its ability to enhance excitation and contraction coupling (ECC) activity in Srsf1 mutant cardiomyocytes have been proposed as a possible cause of the phenotype in mutant mice (14). Ablation of another SR protein, SRSF10 (SRp38), from the mouse also leads to heart defects (15). SRSF10 has been shown to regulate the splicing of Triadin, an important component of ECC machinery (15). Interestingly, conditional deletion of Srsf2 from the heart leads to DCM with little splicing misregulation but instead affects the expression of the calcium channel Ryr2 (16). It is striking that these SR proteins affect ECC activity in the heart by directly regulating the expression/splicing of distinct players in this machinery. Because these studies were conducted before the advent of next-generation RNA sequencing, only a few splicing targets specifically regulated by these SR proteins were identified. A more comprehensive study of the effects of deleting the genes encoding these proteins from the heart on the splicing program has not been reported.In contrast to SR proteins, specific functions of hnRNP proteins in cardiac pre-mRNA splicing have not been determined. In this report, we selectively inactivated the expression of one of the most abundant hnRNP proteins—hnRNP U—in the heart. We found that Hnrnpu mutant mice develop a lethal DCM phenotype, with death occurring around 2 wk after birth. There are multiple cardiac defects in mutant hearts accompanied by many splicing alterations. Some of these splicing targets are commonly regulated by hnRNP U and other SR and RBM proteins. We also identified many hnRNP U-specific splicing targets in the heart, including an ECC component Junctin. The protein product of the alternatively spliced Junctin isoform is N-glycosylated at a specific asparagine site in Hnrnpu mutant cells and could contribute to abnormal cardiac function. Our study also enables comparisons of the roles of different splicing factors in heart development and function.     

91例胃粘膜EB病毒感染的检测

ＥＢ病毒是一种肿瘤病毒，与人类鼻咽癌、淋巴瘤关系密切。近年来ＥＢ病毒相关性胃癌在国外已有报道。本文通过胃镜活检，对９１例胃粘膜行ＰＣＲ方法检测ＥＢ病毒感染。一、材料与方法：９１例患者均为我院１９９６年３月～６月门诊及住院胃镜检查者。男５８例，女３３例...     

A technique for the flow cytometric analysis of lymphocytes bearing histamine receptors

Histamine receptors have been demonstrated on lymphocyte membranes by a variety of techniques. We now report a method that allows for the flow cytometric analysis of histamine receptors on human peripheral T cells. Histamine is conjugated to fluoresceinated human albumin by the coupling agent ECDI. This conjugated histamine compound (FHA-his) binds to approximately 45% of T cells. Fluoresceinated human albumin alone (FHA), not conjugated to histamine, does not bind to T cells. In addition, unconjugated histamine can inhibit completely the binding seen with FHA-his. We conclude that this technique demonstrates specific FHA-his binding to histamine receptors on T cells and can be used to determine the number of cells bearing such receptors. In addition, the reagent could be used with a cell sorter to isolate distinct histamine-receptor-bearing (HR+) cells for further immunologic study.     

Adoptive immunotherapy evaluating escalating doses of donor leukocytes for relapse of chronic myeloid leukemia after bone marrow transplantation: separation of graft-versus-leukemia responses from graft-versus-host disease

Infusions of large numbers (> 10(8)/kg) of donor leukocytes can induce remissions in patients with chronic myeloid leukemia (CML) who relapse after marrow transplantation. We wanted to determine if substantially lower numbers of donor leukocytes could induce remissions and, if so, whether this would reduce the 90% incidence of graft-versus-host disease (GVHD) associated with this therapy. Twenty-two patients with relapsed CML were studied: 2 in molecular relapse, 6 in cytogenetic relapse, 10 in chronic phase, and 4 in accelerated phase. Each patient received escalating doses of donor leukocytes at 4- to 33-week intervals. Leukocyte doses were calculated as T cells per kilogram of recipient weight. There were 8 dose levels between 1 x 10(5) and 5 x 10(8). Lineage-specific chimerism and residual leukemia detection were assessed using sensitive polymerase chain reaction (PCR) methodologies. Nineteen of the 22 patients achieved remission. Remissions were achieved at the following T-cell doses: 1 x 10(7) (n = 8), 5 x 10(7) (n = 4), 1 x 10(8) (n = 3), and 5 x 10(8) (n = 4). To date, 15 of the 17 evaluable patients have become BCR-ABL negative by PCR. The incidence of GVHD was correlated with the dose of T cells administered. Only 1 of the 8 patients who achieved remission at a T-cell dose of 1 x 10(7)/kg developed GVHD, whereas this complication developed in 8 of the 11 responders who received a T-cell dose of > or = 5 x 10(7)/kg. Three patients died in remission, 1 secondary to marrow aplasia, 1 of respiratory failure and 1 of complications of chronic GVHD. Sixteen patients who were mixed T-cell chimeras before treatment became full donor T-cell chimeras at the time of remission. Donor leukocytes with a T-cell content as low as 1 x 10(7)/kg can result in complete donor chimerism together with a potent graft-versus-leukemia (GVL) effect. The dose of donor leukocytes or T cells used may be important in determining both the GVL response and the incidence of GVHD. In many patients, this potent GVL effect can occur in the absence of clinical GVHD.     

Differential effect of Serratia protease on platelet surface glycoproteins Ib and V

The effect of a zinc metalloprotease from Serratia marcescens on platelet surface glycoproteins (GP) Ib and V was analyzed. Increasing protease treatments caused progressive loss of GP Ib with appearance of the major fragment, glycocalicin, in the supernatant solution. No GP V was detected in the supernatant solution, and protease-pretreated platelets had the same capacity as control platelets to release fragment 1 of GP V in response to thrombin. The Serratia protease- pretreated platelets did show the lag before thrombin-induced dense granule secretion, characteristic of platelets modified by pretreatment with other nonstimulating proteases. Treatment with Serratia protease gives the only demonstrated selective loss of GP Ib without apparent effect on GP V. It suggests that GP V (1) does not depend on GP Ib for its association with platelets and (2) is not the substrate for protease modification of platelet function.     

Management of hepatitis B in patients with HBeAg-negative disease

Chronic hepatitis B with negative hepatitis B e antigen (HBeAg) is becoming a more prevalent form of chronic hepatitis B. This change is the result of selection pressure on the virus leading to a precore or double core promoter mutation of hepatitis B virus that either abolishes or downregulates synthesis of HBeAg. De novo acute infection with HBeAg-negative mutant virus rarely leads to chronic infection but usually results in acute hepatitis with a course ranging from benign to fulminant. Chronic HBeAg-negative hepatitis B is thought to evolve from wildtype HBeAg-positive chronic hepatitis B and is associated with a worse natural history than HBeAg-positive disease. Long-term treatment is required to maintain suppression of viral replication when using the oral nucleoside or nucleotide analogues, which have improved management of this condition. However, the need for extended therapy makes strategies to reduce or avoid resistance to antiviral drugs an important consideration.