Detection of PML-RAR alpha in patients with APL during follow-up period

OBJECTIVE

To evaluate the significance of PML-RAR alpha transcripts in patients with acute promyelocytic leukemia (APL) during remission period and to follow up the patients through monitoring aberrant gene expression.

PATIENTS AND METHODS

This study included 17 patients with APL (5 females and 12 males). Another 19 APL patients during relapse served as control. RNA extraction was obtained through the single-step method. By means of reverse transcriptase polymerase chain reaction (PCR), the PML-RAR alpha was detected in the sample mRNA.

RESULTS

Nine out of 10 patients with complete remission (CR) duration shorter than 3 years were positive. Four cases became negative and three remained positive among 7 cases in a long remission of over 3 years. The difference of the positive rate of PML-RAR alpha transcripts between the 2 groups was significant (P < 0.05). Four among 12 positive cases relapsed. No evidence of relapse was present in the 5 negative patients after 9.6 +/- 3.9-month follow-up. Further treatment was therefore given to the 4 positive patients whose treatment was already ceased at that time. By this management they were all in CR during the following 10-month observation.

CONCLUSIONS

RT-PCR detection for PML-RAR alpha transcripts was useful in monitoring MRD and guiding further treatment to obtain a long remission. Persistently positive transcripts were closely associated with the relapse.

Expression of monocyte chemoattractant protein-1 and interleukin-8 receptors on subsets of T cells: correlation with transendothelial chemotactic potential

The differential expression of chemokine receptors may be an important mechanism for the regulation of T cell migration. To test this, we examined the expression and function of the monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-8 receptors on various population of T cells. Using a simple and reliable transendothelial chemotaxis assay, both MCP-1 and IL-8 were shown to be chemotactic for subsets of blood T cells, although the relative response varied from donor to donor. To examine receptor expression and correlate it with chemotaxis of T cell subsets, monoclonal antibodies (mAb) to the receptors were produced by immunizing mice either with synthetic peptides (MCP-1 receptor), or with receptor transfectants (IL-8 receptors A and B). A flow cytometric analysis of blood T cells with an anti-MCP-1 receptor mAb revealed low expression on the CD26hi subset and undetectable expression on other T cells. Staining of T cells with anti-Il-8RA and anti-IL-8RB showed much higher levels of expression, but only on a subset of CD3+ cells which were CD8+ and CD56+. That IL-8 and MCP-1 attracted distinct subsets of T cells was best illustrated using the CD26 marker, since IL-8R+ T cells were CD26-, whereas T cells expressing detectable MCP-1R or which responded to MCP-1 in chemotaxis assays were CD26hi. T cells activated in vitro with anti-CD3 up-regulated expression of the MCP-1 receptor, but not the IL-8 receptors, and were attracted to MCP-1 much more efficiently than resting T cells. These results show that there is a clear distinction between the IL-8 and MCP-1-responsive T cell populations and that chemokine receptor expression on T cells may be regulated with respect to linkage as well as cellular activation.

Cooperation of tyrosine kinases p72syk and p53/56lyn regulates calcium mobilization in chicken B cell oxidant stress signaling

A chicken B cell line DT40 and its syk-negative or lyn-negative mutants were used to investigate the roles of protein-tyrosine kinases in oxidant stress signaling. The data presented here for wild-type cells demonstrate that hydrogen peroxide stimulates p53/56lyn-dependent tyrosine phosphorylation and activation of p72syk, and induces a rapid and prolonged elevation of intracellular calcium, which consists of calcium release from intracellular stores and influx from the extracellular space. Hydrogen-peroxide-triggered calcium mobilization was impaired in both syk-negative and lyn-negative cells, which was mainly due to the loss of calcium release from intracellular stores. Further studies indicated that inositol trisphosphate production was also abolished in both syk-negative and lyn-negative cells, which is consistent with the loss of calcium release. Taken together, these observations suggest that the defect of p72syk or p53/56lyn was responsible for the abnormality of calcium mobilization in both lyn-negative and syk-negative cells, and that both p72syk and p53/56lyn might regulate calcium mobilization through the phosphatidylinositol pathway in B cell oxidant stress signaling.

Cloning of the human eosinophil chemoattractant, eotaxin. Expression, receptor binding, and functional properties suggest a mechanism for the selective recruitment of eosinophils

The CC chemokine eotaxin, identified in guinea pigs and also recently in mice, may be a key element for the selective recruitment of eosinophils to certain inflamed tissues. Using a partial mouse eotaxin CDNA probe, the human eotaxin gene was cloned and found to be 61.8 and 63.2% identical at the amino acid level to guinea pig and mouse eotaxin. Human eotaxin protein was a strong and specific eosinophil chemoattractant in vitro and was an effective eosinophil chemoattractant when injected into the skin of a rhesus monkey. Radiolabeled eotaxin was used to identify a high affinity receptor on eosinophils (0.52 nM Kd), expressed at 4.8 x 10(4) sites per cell. This receptor also bound RANTES and monocyte chemotactic protein-3 with lower affinity, but not macrophage inflammatory protein-1 alpha. Eotaxin could desensitize calcium responses of eosinophils to RANTES and monocyte chemotactic protein-3, although RANTES was able to only partially desensitize eosinophil calcium responses to eotaxin. Immunohistochemistry on human nasal polyp with antieotaxin mAbs showed that certain leukocytes as well as respiratory epithelium were intensely immunoreactive, and eosinophil infiltration occurred at sites of eotaxin upregulation. Thus eotaxin in humans is a potent and selective eosinophil chemoattractant that is expressed by a variety cell types in certain inflammatory conditions.

Fibrocartilage associated with human tendons and their pulleys

The presence of fibrocartilage in tendons that wrap around bony or fibrous pulleys is well known. It is an adaptation to resisting compression or shear, but the extent to which the structure of most human tendons is modified where they contact pulleys is less clear, for there has been no single comprehensive survey of a large number of sites. Less is known of the structure of the corresponding pulleys. In the present study, 38 regions of tendons that wrap around bony pulleys or pass beneath fibrous retinacula have been studied in routine histology sections taken from each of 2 or 3 elderly dissecting room cadavers. Most of the corresponding pulleys have also been examined. Fibrocartilage was present in 22 of the 38 tendon sites and it was most conspicuous where the tendons pressed predominantly against bone rather than retinacula and where they showed a large change in direction. Fibrocartilage was more characteristic of tendons at the ankle than the wrist, probably because the long axis of the foot is at right angles to that of the leg. There was considerable variation in the structure of tendon fibrocartilage. The most fibrocartilaginous tendons had oval or round cells embedded in a highly metachromatic matrix with interwoven or spiralling collagen fibres. At other sites, fibrocartilage cells were arranged in rows between parallel collagen fibres. The differences probably relate to differences in development. A single tendon could be modified at successive points along its length and fibrocartilage could be present in the endotenon and epitenon as well as in the tendon itself. Pathological changes seen in 'wrap around' tendons were fragmentation and partial delamination of the compressed surface, chondrocyte clustering, fatty infiltration and bone formation. Three types of pulleys were described for tendons--bony prominences and grooves, fibrous retinacula and synovial joints. The extent of cartilaginous differentiation on the periosteum of bony pulleys frequently mirrored that in the corresponding tendon. The cartilage or fibrocartilage prevents the tendon from 'sawing' through the bone. Some of the best known retinacula were largely fibrous, though the inferior peroneal retinaculum and the trochlea for the superior oblique were cartilaginous. The results underline the considerable regional heterogeneity in different tendons and their pulleys. They show that one tendon is not like another and that tendons may need to be carefully selected for particular surgical transfers or joint reconstructions.

[Apolipoprotein (a) polymorphism in relation to coronary heart disease in Chinese Han nationality]

We investigated the association of apolipoprotein (a) [apo(a)]polymorphism with coronary heart disease in Chinese Han nationality. The effects of the apo(a) phenotypes on lipoprotein [Lp (a)], total cholesterol (TC), high density lipoprotein cholesterol (HDL), and triglyceride (TG) levels were also investigated. The CHD group consisted of 105 patients (85 were survivors from previous myocardial infarction and 20 had > or = 75% narrowing in at least one of the major coronary arteries found by coronary angiography). The control group included 102 healthy individuals who had no symptoms and clinical signs of cardiovascular diseases. Apo(a) phenotype was performed by SDS-polyacrylamide gel electrophoresis (PAGE) under reducing conditions followed by immunoblotting. Determination of (a) Lp(a) and other lipoproteins were also performed. The apo(a) low molecular weight phenotypes (B, S1, S2) were more frequent in the CHD patients than in the healthy individuals (30.5% vs 15.7%, P < 0.05). Lp(a) concentrations were significantly higher in the patients than in the controls (257 +/- 225 mg/L vs 145 +/- 157 mg/L, P < 0.001). The results from stepwise logistic regression analysis indicated that apo(a) phenotype was a significant predictor of CHD, independent of TC, LDL-C and HDL-C. But apo(a) molecular weight was inversely related to Lp(a) levels. The apo(a) low molecular weight phenotypes associated with elevated Lp(a) levels was a primary genetic risk factor for CHD in Han Chinese.

Cyclic AMP-elevating agents negatively regulate the activation of p72syk in N-formyl-methionyl-leucyl-phenylalanine receptor signaling

Here we investigated the involvement of the non-receptor protein-tyrosine kinase p72syk in formyl methionyl-leucyl-phenylalanine (fMLP) receptor signaling. The activity of p72syk began to rise from 15 s and reached to maximum within 2-5 min after 5 microM fMLP stimulation in porcine polymorphonuclear neutrophils (PMNs). Cyclic AMP (cAMP)-elevating agents, prostaglandin E2 (PGE2) and forskolin, or dibutyryl cAMP partially suppressed p72syk activities stimulated by fMLP in PMNs. Pretreatment with an inhibitor of cAMP-dependent protein kinase abolished the suppression of the fMLP-induced p72syk activation by these cAMP-elevating agents. It was also observed that cAMP-dependent protein kinase phosphorylates p72syk on serine residues in vitro. These results indicate a possibility that cAMP-dependent protein kinase negatively regulates the activation of p72syk in fMLP-receptor signaling.

Rapid construction of integrated maps using inner product mapping: YAC coverage of human chromosome 11

Inner product mapping (IPM) has been proposed as a hybridization-based method for achieving low-cost, high-throughput, high-resolution radiation hybrid (RH) mapping of clones. Using Alu-PCR products of chromosome 11-specific clones, we serially hybridized a set of RHs against gridded filters of YACs having an average size of 350 kb. We then combined these hybridization data with preexisting RH map data to build an inner product map. This binning of 865 YACs provides the first high-resolution large-scale (> twofold redundancy) clonal coverage of human chromosome 11 and is the first inner product map ever constructed. We verified the accuracy and precision of this chromosome 11 map by performing a novel likelihood analysis on independent YAC hybridization data. These results establish that IPM is a highly rapid, inexpensive, accurate, and precise large-scale long-range mapping method, particularly when preexisting RH maps are available, and that IPM can replace or complement more conventional short-range mapping methods. IPM may enable the rapid construction of sequence-ready maps and the binning of expressed sequences.

Activation and tyrosine phosphorylation of p72syk as well as calcium mobilization after hydrogen peroxide stimulation in peripheral blood lymphocytes

To determine the regulatory role of p72syk in lymphocyte activation, peripheral blood lymphocytes were treated with 10 mM hydrogen peroxide. Hydrogen peroxide induced a rapid elevation of p72syk activity (4-6-fold) and a dramatic increase in tyrosine phosphorylation of a number of cellular proteins, including phospholipase C gamma 1 (PLC gamma 1) and p72syk. Monoclonal antibodies to PLC gamma 1 co-precipitated p72syk from hydrogen peroxide-stimulated cell lysates, but not from unstimulated cell lysates. Furthermore, we observed a rise in intracellular Ca2+, corresponding to the combination of extracellular Ca2+ influx and the release from intracellular Ca2+ stores. Extracellular Ca2+ influx was necessary for the sustenance of p72syk activity, but not for the initiation of p72syk activation induced by hydrogen peroxide. Taken together, these data suggested that one possible role of p72syk was to activate PLC gamma 1, at least in part through tyrosine phosphorylation, and then to trigger calcium mobilization in pig peripheral blood lymphocytes in response to hydrogen peroxide stimulation.

A YAC contig spanning the ataxia-telangiectasia locus (groups A and C) at 11q22-q23

Ataxia-telangiectasia (A-T) is an autosomal recessive disease involving cerebellar degeneration, immunodeficiency, cancer predisposition, chromosomal instability and radiosensitivity. A-T is heterogeneous, and the majority of A-T cases are associated with two complementation groups, A and C. The ATA and ATC loci are closely linked at chromosome 11q22-q23. Recombination mapping and linkage disequilibrium analysis have confined both loci between the markers D11S1817 and D11S927, spaced approximately 3.5 Mb apart. Isolation in yeast artificial chromosomes of the genomic segment defined by these loci is essential to identify the gene or genes containing the ATA and ATC mutations. A YAC contig spanning 4.5 Mb, which includes the D11S1817-D11S927 interval, was constructed using two whole genome libraries (ICRF and St. Louis), and a chromosome 11-specific library. Construction of this contig was expedited by prior generation of a region-specific ICRF sublibrary using Alu-PCR products derived from a radiation hybrid. The contig was expanded further by screening the libraries with Alu-PCR products derived from YAC clones and with STSs from YAC ends. YAC clones were aligned by fingerprinting with moderately repetitive probes.

Mechanisms in CD4 antibody-mediated transplantation tolerance: kinetics of induction, antigen dependency and role of regulatory T cells

CBA/Ca mice may be made tolerant to minor histoincompatible B10.BR skin grafts by treatment with a short course of non-depleting anti-mouse CD4 and CD8 monoclonal antibodies (mAb), during the transplantation period. We wished to determine when, in relation to antibody therapy, the T cells became tolerant. This was investigated by a series of adoptive transfer experiments in which mAb-treated cells were removed from therapeutic antibody at defined times after skin grafting, and exposed to fresh antigen in the absence of further mAb treatment. We show here that T cells do not become fully tolerant until 5 weeks after skin grafting. If antibody therapy is continued for the full 5 weeks, T cell tolerance can still be established, suggesting that antibody therapy does not prevent lymphocytes from registering the presence of antigen. Once the tolerant state is established, it is difficult to break that tolerance by lymphocyte infusions from normal donors. This "resistance" is mediated by T cells of the tolerant host. We show that the maintenance of both tolerance and "resistance" requires a continuous supply of antigen. When tolerant cells were "parked" in T cell-depleted mice, tolerance and "resistance" were eventually lost by 6 months. In contrast, "parked" cells exposed to fresh antigen at any time up to 4 months remained tolerant and "resistant" indefinitely. Finally, we wished to establish whether "resistance" was peculiar to this form of peripheral tolerance, or whether it might also be present in tolerance considered to be classically central. We observed resistance to be greater in the mAb-treated peripherally tolerant group, but noted that some of the centrally tolerant animals also exhibited a level of resistance above that of T cell-ablated controls. This suggests that a tolerance mechanism whose role is only minor in central tolerance may have a major role in antibody-mediated peripheral tolerance.

Interleukin 2 mediates p72syk activation in peripheral blood lymphocytes

The ability of interleukin 2 (IL-2) to stimulate p72syk activity in intact porcine peripheral blood lymphocytes was examined. We demonstrated that IL-2 activated p72syk in a time- and dose-dependent manner, for which its peak time and maximum responsive dose were 5 min and 100 U/ml, respectively. This activation was observed only in cytosolic fractions and not in membrane ones. However, IL-2 failed to induced calcium mobilization. Moreover, IL-2-inducible p72synk activation was not affected when extra- intracellular calcium was depleted. These data suggest that the IL-2 signaling pathway through p72syk in peripheral blood lymphocytes is different, at least in part, from other agonists, such as concanavalin A in polymorphonuclear neutrophils which can trigger both the activation of p72syk and intracellular calcium mobilization.

Dephosphorylation of the small heat shock protein Hsp27 in vivo by protein phosphatase 2A

The phosphorylation of the Hsp27 complex is rapidly altered in MRC-5 cells when they are exposed to mitogens, cytokines, stress, or serine/threonine protein phosphatase inhibitors. Here we performed experiments to identify which cellular protein phosphatase (PP1, PP2A, or PP2B) is responsible for the in vivo phosphorylation/dephosphorylation of Hsp27. In their purified forms, PP2A dephosphorylates Hsp27 more effectively than PP2B, whereas PP1 is weakly active. Measurements of enzyme activity of lysates derived from inhibitor-treated cells indicated that Hsp27 phosphatase activity is equally sensitive to okadaic acid (PPI/PP2A inhibitor) and cyclosporin (PP2B inhibitor) and that both okadaic acid and cyclosporin treatment inhibited Hsp27 phosphatase activity additively. Together the in vitro data suggest that both PP2A and PP2B can dephosphorylate Hsp27. However, the phosphorylation of Hsp27 in vivo is only affected when cells are treated with PP1 and PP2A inhibitors (okadaic acid, calyculin A) or cantharidin (PP2A inhibitor), but not the PP2B inhibitor, cyclosporin A, suggesting PP2A to be the main enzyme dephosphorylating Hsp27 in the cells. Purification and immunoblotting of Hsp27 phosphatase from MRC-5 cells also suggest it to be PP2A and not PP1 or PP2B. The ability of PP2A to dephosphorylate Hsp27 is shown to be regulated by the phosphorylation state of PP2A itself.

Role of tumor necrosis factor in neonatal sepsis

In order to assess the role of tumor necrosis factor (TNF) in neonatal sepsis, plasma TNF levels were determined by a method using L929 cells at the time of septic work-up in 67 neonates. Thirty-three patients with sepsis were found to have significantly higher TNF levels (533.33 +/- 468.74 U/ml; 1 U corresponding to 1.67 pg recombinant TNF) as compared with 34 non-sepsis patients (100.0 +/- 188.97 U/ml) and 30 healthy newborns (27.33 +/- 16.17 U/ml, P < 0.05, respectively). The upper limit of normal plasma TNF levels was 60 U/ml and the best cutoff value for predicting neonatal sepsis was 160 U/ml. This had remarkable sensitivity (88%), specificity (82%), positive predictive value (83%), and negative predictive value (88%). Plasma TNF levels were significantly associated with the occurrence of shock, organ failure, scleroma and outcome. Thus, anti-TNF antibodies might be used in protecting newborns from septic death.

Differential induction of nuclear NF-kappa B by protein phosphatase inhibitors in primary and transformed human cells. Requirement for both oxidation and phosphorylation in nuclear translocation

Phosphoseryl/threonyl protein phosphatase inhibitors, viz. okadaic acid and calyculin-A, failed to induce nuclear factor-kappa B (NF-kappa B) nuclear translocation in several primary human cells although a marked and rapid induction was observed in their simian virus 40 transformed counterparts. Inability to induce NF-kappa B cannot be due to a non-activatable system since NF-kappa B was strongly activated by tumor necrosis factor in all the five primary cell types tested. It is also unlikely that the differential induction was due to differential sensitivity of primary and transformed cells to phosphatase inhibitors as the intracellular phosphatase activities of both cell types were equally inhibited by these inhibitors. However, pretreatment with hydrogen peroxide or buthionine sulfoximine, chemicals known to directly or indirectly elevate the intracellular free-radical levels, enabled okadaic acid to induce nuclear translocation of NF-kappa B in primary cells. Conversely cysteine, an antioxidant and precursor of the free radical scavenger, glutathione, inhibited the induction of NF-kappa B by tumor necrosis factor in primary cells, and by okadaic acid or tumor necrosis factor in transformed cells. These data, taken together, suggest that free radical-dependent oxidation and protein phosphorylation are not independent modes of NF-kappa B induction, but are both required for the release of NF-kappa B from I kappa B. Furthermore, the differential induction of NF-kappa B nuclear translocation by okadaic acid in primary and transformed human cells, reported herein, reflects intrinsic differences in the intracellular oxidative state between the two groups of cells. The induction of NF-kappa B by tumor necrosis factor in primary cells suggests that this cytokine fulfills the requirement for oxidation, possibly by inducing the production of free radicals.

A chromosome 11 YAC library

A targeted yeast artificial chromosome (YAC) library for chromosome 11 has been constructed from the J1 cell line that carries a single human chromosome 11 within a hamster DNA background. Interspecies chimeric clones generated during construction of the library were detected during the screening process and eliminated from the library. Contig assembly becomes much less difficult using such a library as the complexity is decreased and the ends of the clone inserts can be rescued for walking to neighboring clones. The library contains > 1824 clones with an average insert length of 337 kb. This represents a fourfold coverage of chromosome 11 or a > 95% chance of recovering a unique single-copy sequence from the library. Two hundred YAC clones were localized by fluorescence in situ hybridization and found to be randomly distributed along the chromosome. The library has been screened with probes for the chromosome 11 markers HBB, GLUR4, H19, and D11S193. Corresponding YAC clones have been isolated for each locus. This analysis has indicated that the library is unbiased, that cognate YAC clones can be recovered with chromosome 11 markers, and that extensive contig assembly should be feasible.