Metal ion type significantly affects the morphology but not the activity of lipase–metal–phosphate nanoflowers

Using different metal ions to prepare hybrid lipase nanoflowers resulted in a variety of different morphologies, but did not significantly affect the specific activity of the enzyme.

Identification and characterization of a lymphocytic Rho-GTPase effector: rhotekin-2

Rhotekin belongs to the group of proteins containing a Rho-binding domain that are target peptides (effectors) for the Rho-GTPases. We previously identified a novel cDNA with homology to human rhotekin and in this study we cloned and characterized the coding region of this novel 12-exon gene. The ORF encodes a 609 amino-acid protein comprising a Class I Rho-binding domain and pleckstrin homology (PH) domain. Cellular cDNA expression of this new protein, designated Rhotekin-2 (RTKN2), was shown in the cytosol and nucleus of CHO cells. Using bioinformatics and RTPCR we identified three major splice variants, which vary in both the Rho-binding and PH domains. Real-time PCR studies showed exclusive RTKN2 expression in pooled lymphocytes and further purification indicated sole expression in CD4(pos) T-cells and bone marrow-derived B-cells. Gene expression was increased in quiescent T-cells but negligible in activated proliferating cells. In malignant samples expression was absent in myeloid leukaemias, low in most B-cell malignancies and CD8(pos) T-cell malignancies, but very high in CD4(pos)/CD8(pos) T-lymphoblastic lymphoma. As the Rho family is critical in lymphocyte development and function, RTKN2 may play an important role in lymphopoiesis.

ORP3 splice variants and their expression in human tissues and hematopoietic cells

ORP3 is a member of the newly described family of oxysterol-binding protein (OSBP)-related proteins (ORPs). We previously demonstrated that this gene is highly expressed in CD34(+) hematopoietic progenitor cells, and deduced that the "full-length" ORP3 gene comprises 23 exons and encodes a predicted protein of 887 amino acids with a C-terminal OSBP domain and an N-terminal pleckstrin homology domain. To further characterize the gene, we cloned ORP3 cDNA from PCR products and identified multiple splice variants. A total of eight isoforms were demonstrated with alternative splicing of exons 9, 12, and 15. Isoforms with an extension to exon 15 truncate the OSBP domain of the predicted protein sequence. In human tissues there was specific isoform distribution, with most tissues expressing varied levels of isoforms with the complete OSBP domain; while only whole brain, kidney, spleen, thymus, and thyroid expressed high levels of the isoforms associated with the truncated OSBP domain. Interestingly, the expression in cerebellum, heart, and liver of most isoforms was negligible. These data suggest that differential mRNA splicing may have resulted in functionally distinct forms of the ORP3 gene.

Identification and characterization of a novel family of mammalian ependymin-related proteins (MERPs) in hematopoietic, nonhematopoietic, and malignant tissues

Evidence is presented for a family of mammalian homologs of ependymin, which we have termed the mammalian ependymin-related proteins (MERPs). Ependymins are secreted glycoproteins that form the major component of the cerebrospinal fluid in many teleost fish. We have cloned the entire coding region of human MERP-1 and mapped the gene to chromosome 7p14.1 by fluorescence in situ hybridization. In addition, three human MERP pseudogenes were identified on chromosomes 8, 16, and X. We have also cloned the mouse MERP-1 homolog and an additional family member, mouse MERP-2. Then, using bioinformatics, the mouse MERP-2 gene was localized to chromosome 13, and we identified the monkey MERP-1 homolog and frog ependymin-related protein (ERP). Despite relatively low amino acid sequence conservation between piscine ependymins, toad ERP, and MERPs, several amino acids (including four key cysteine residues) are strictly conserved, and the hydropathy profiles are remarkably alike, suggesting the possibilities of similar protein conformation and function. As with fish ependymins, frog ERP and MERPs contain a signal peptide typical of secreted proteins. The MERPs were found to be expressed at high levels in several hematopoietic cell lines and in nonhematopoietic tissues such as brain, heart, and skeletal muscle, as well as several malignant tissues and malignant cell lines. These findings suggest that MERPs have several potential roles in a range of cells and tissues.

ORP-3, a human oxysterol-binding protein gene differentially expressed in hematopoietic cells

Using differential display polymerase chain reaction, a gene was identified in CD34(+)-enriched populations that had with low or absent expression in CD34(-) populations. The full coding sequence of this transcript was obtained, and the predicted protein has a high degree of homology to oxysterol-binding protein. This gene has been designated OSBP-related protein 3 (ORP-3). Expression of ORP-3 was found to be 3- to 4-fold higher in CD34(+) cells than in CD34(-) cells. Additionally, expression of this gene was 2-fold higher in the more primitive subfraction of hematopoietic cells defined by the CD34(+)38(-) phenotype and was down-regulated with the proliferation and differentiation of CD34(+) cells. The ORP-3 predicted protein contains an oxysterol-binding domain. Well-characterized proteins expressing this domain bind oxysterols in a dose-dependent fashion. Biologic activities of oxysterols include inhibition of cholesterol biosynthesis and cell proliferation in a variety of cell types, among them hematopoietic cells. Characterization and differential expression of ORP-3 implicates a possible role in the mediation of oxysterol effects on hematopoiesis.

Induction of osteoclasts from CD14-positive human peripheral blood mononuclear cells by receptor activator of nuclear factor kappaB ligand (RANKL)

Osteoclasts are bone-resorbing cells that are derived from haemopoietic precursors, including cells present in peripheral blood. The recent identification of RANKL [receptor activator of nuclear factor (NF)-kappaB ligand], a new member of the tumour necrosis factor ligand superfamily that has a key role in osteoclastogenesis, has allowed the in vitro generation of osteoclasts in the absence of cells of the stromal/osteoblast lineage. Human peripheral blood mononuclear cells (PBMC) cultured in vitro with soluble RANKL and human macrophage colony-stimulating factor form osteoclasts. However, PBMC are heterogeneous, consisting of subsets of monocytes and lymphocytes as well as other blood cells. As the CD14 marker is strongly expressed on monocytes, the putative osteoclast precursor in peripheral blood, we have selected CD14(+) cells from PBMC to examine their osteoclastogenic potential and their expression of novel members of the tumour necrosis factor superfamily involved in osteoclastogenesis. Highly purified CD14(+) cells demonstrated mRNA expression of receptor activator of NF-kappaB, but no expression of RANKL or osteoprotegerin, whereas PBMC expressed mRNAs for all three factors. CD14(+) (but not CD14(-)) cells cultured on bone slices for 21 days with human macrophage colony-stimulating factor and soluble RANKL generated osteoclasts and showed extensive bone resorption. Similar numbers of osteoclasts were generated by 10(5) CD14(+) cells and 10(6) PBMC, but there was significantly less intra-assay variability with CD14(+) cells, suggesting the absence of stimulatory/inhibitory factors from these cultures. The ability of highly purified CD14(+) cells to generate osteoclasts will facilitate further characterization of the phenotype of circulating osteoclast precursors and cell interactions in osteoclastogenesis.

Molecular analysis of transient cytogenetic relapse after allogeneic bone marrow transplantation for chronic myeloid leukaemia

Serial quantification of residual disease in CML patients after allogeneic BMT is useful for early detection of relapse. However, the fact that some cytogenetic relapses appear to be transient may complicate protocols for early therapeutic intervention based on molecular analysis and could result in the unnecessary treatment of some patients. To determine the frequency and significance of transient cytogenetic relapse, we have studied serial samples from 98 CML patients after allogeneic BMT by conventional cytogenetics and competitive RT-PCR for BCR-ABL mRNA. During the period of study, 26 patients had cytogenetic or haematologic evidence or relapse. In four cases (15% of those who relapsed; 4% of all patients) relapse appeared to be transient; i.e., subsequent marrow samples were completely Ph chromosome-negative despite the fact that there had been no change in treatment, including the level of immunosuppression. BCR-ABL mRNA levels broadly paralleled the cytogenetic findings. Of these four patients, two subsequently progressed to frank haematologic relapse and two remained strongly positive for BCR-ABL transcripts and are therefore presumably still at risk of relapse. Analysis of B cell-enriched, T cell-enriched and lymphoid-depleted fractions for three patients demonstrated that transient relapse was not due to the proliferations of BCR-ABL-positive lymphoid cells. In contrast, BCR-ABL-positive myeloid precursor cells were detected in two of three patients tested. We conclude that transient cytogenetic relapse followed by sustained remission is a relatively infrequent occurrence after current allogeneic transplant regimens.

Quantitation of mafosfamide-resistant pre-colony-forming units in allogeneic bone marrow transplantation: relationship with rate of engraftment and evidence for long-lasting reduction in stem cell numbers

Current assays of human committed-stem cells are of limited value in predicting the rate of engraftment or in assessing the integrity of the stem cell pool after allogeneic bone marrow (BM) transplantation (BMT). We have used a limiting dilution assay of mafosfamide-resistant progenitors (pre-colony-forming units [CFU]), which are ancestral to committed progenitors such as CFU-granulocyte-macrophage (GM) to analyze the kinetics of myeloid engraftment after BMT and to assess the size of the stem cell pool at intervals up to 66 months thereafter. In 24 patients transplanted for chronic myeloid leukemia in chronic phase (eight with matched unrelated donors and 16 with sibling donors), the rate of neutrophil engraftment correlated strongly with the number of pre-CFU transfused per kilogram recipient body weight (r = .7, P < .005) but not with CFU-GM per kilogram or nucleated cells per kilogram. In 25 patients studied 6 to 66 months after allogeneic BMT, the mean number of pre-CFU in the marrow was 3.1/10(5) mononuclear cells (MNC) (median, 3.47; range, 0.4 to 23.3), compared with 24.7/10(5) MNC (median, 27.3; range, 4.2 to 180) in 25 normal subjects. CFU-GM were also reduced in these patients, but with considerable overlap into the normal range (mean +/- SD: 54 +/- 45.6 per 10(5) MNC; normal, 129 +/- 61.6). Low pre-CFU but not low CFU-GM levels were associated with reduced peripheral blood white blood cell counts in post-BMT patients. Pre-CFU and CFU-GM levels were not related to the interval posttransplant and remained low for up to 66 months. We conclude that the pre-CFU assay measures a population of stem/progenitor cells that are important in the kinetics of engraftment after allogeneic BMT. Our data suggest that pre-CFU levels may remain low for some years after BMT in humans.

Antisense BCR-ABL oligomers cause non-specific inhibition of chronic myeloid leukemia cell lines

We have examined the effects of antisense oligomers (AOs) of various lengths, sequences and chemistry on the proliferation of eight different cell lines, five derived from patients with chronic myelogenous leukemia (CML) and three from other sources. In general, phosphodiester AOs were inactive, presumably due to degradation by nucleases present in fetal calf serum. Both BA2 and B3A2 phosphorothiolate AOs (but not corresponding sense oligomers) significantly inhibited the proliferation of three CML cell lines (BV173, LAMA84, and KYO1), but the effect was independent of the type of breakpoint expressed by each cell line, suggesting that the inhibition was sequence dependent but not sequence specific. The CML cell lines tested showed different sensitivities to inhibition of proliferation by AOs--lines with defective expression of the normal ABL protooncogene (e.g. BV173) were more readily inhibited than lines with a normal ABL message (e.g. K562). We conclude that further studies are necessary to delineate the precise mechanism(s) by which CML cell proliferation is inhibited by AOs.

Expression of the Tn antigen in myelodysplasia, lymphoma, and leukemia

Expression of the normally cryptic blood group antigen Tn has occasionally been reported in hematologic disease, but the true frequency of this change is not known. A mouse monoclonal antibody (FBT3) and immunohistochemistry were used to examine expression of the Tn antigen. Expression was not detected in 35 normal bone marrow aspirates examined, but it was detected in 5 of 725 abnormal bone marrow aspirates, including 2 (3.6%) of 55 cases of de novo acute nonlymphocytic leukemia and 2 cases that terminated in acute nonlymphocytic leukemia. In two patients, one with acute myeloblastic leukemia and the other in blast transformation of chronic myeloid leukemia, the Tn antigen was expressed on 2 percent of blast cells. In one case of non-Hodgkin's lymphoma, 4 percent of normal myeloid cells expressed the antigen. In the other two cases, one of acute myelomonocytic leukemia and the other of myelodysplasia, only 2 to 8 percent of myeloid and erythroid cells initially were Tn positive. Subsequent serial immunohistochemical studies of bone marrow aspirates and peripheral blood in these two cases showed increasing numbers of Tn-positive erythroid and myeloid cells 8 to 12 months before polyagglutination was detected serologically. Tn-positive cells increased to > 90 percent in the terminal phase in both cases of both diseases. The results suggest that Tn expression in these two patients may have conferred a growth advantage to the cells and could be related to disease progression.

Adult T-cell leukaemia lymphoma in an aborigine

A 44-year-old Aborigine with Adult T-cell Leukaemia/Lymphoma (ATLL) due to HTLV-I is reported. He presented with transverse myelitis of subacute onset, and subsequently developed frank T-cell leukaemia complicated by splenomegaly and hypercalcaemia. Cell surface marker studies showed a phenotype of CD3+ CD4+ CD8- CD25+, and serological and molecular studies confirmed HTLV-I infection. This is the first report of ATLL in an Australian Aborigine.