Search PubMed⌕ Search

Biomedical subjects

A Tobler

Publications and source records attributed to A Tobler.

At least 37 records · Page 2Linked to original sources
PubMed2000

Enhanced p73 expression during differentiation and complex p73 isoforms in myeloid leukemia.

The p53 homologue p73 is expressed in at least six different isoforms (alpha, beta, gamma, delta, epsilon, and zeta), but unlike p53 it has rarely been found mutated in human cancers. However, altered expression of this gene has been reported in cancer cells. In order to understand if p73 is involved in normal and malignant development of myeloid cells, we investigated the expression pattern of the different p73 isoforms in progenitor and mature normal myeloid cells as well as in cells derived from acute and chronic myeloid leukemias. The results show that expression of p73 is markedly enhanced during differentiation of myeloid leukemic cells and that leukemic blasts from patients show an increased expression of the shorter p73 isoforms (gamma, delta, epsilon, zeta). In particular the epsilon isoform is only expressed in leukemic cells and completely absent in mature myeloid cells. Altogether our data suggest that p73 is involved in myeloid differentiation and its altered expression is involved in leukemic degeneration.

Acute Disease↗
PubMed2000

Differential expression of p73 splice variants and protein in benign and malignant ovarian tumours.

The p73 gene encodes a protein with substantial structural and functional similarities to the tumour-suppressor p53. Alternative splicing of p73 mRNA leads to expression of 6 known RNA species and proteins (alpha, beta, gamma, delta, epsilon, zeta). We analysed the expression of these splice variants in ovarian adenocarcinoma by RT-PCR followed by detection of amplicons with the Southern technique and by immunoblot in 32 malignant and benign epithelial ovarian tumour specimens and 3 ovarian adenocarcinoma cell lines (A2780, 2008, OVCAR-3). p73alpha mRNA was expressed in all 17 ovarian cancer specimens, and 14 of 17 expressed at least 3 splice variants. In contrast, a different expression pattern was present in the ovarian adenomas: p73alpha was detected in 6 of 12 benign tumours, and only 1 adenoma expressed 3 splice variants. p73 protein was expressed in 9 of 16 ovarian cancer specimens, in all cell lines and in 1 of 3 borderline tumours. In contrast, none of 9 ovarian adenomas expressed detectable amounts of p73 protein. Expression of p73 mRNA and protein was not correlated with FIGO stage and histological grade, but we observed a significant correlation with over-expression of p53 protein. In summary, epithelial ovarian cancers express a more complex p73 isoform pattern and higher levels of p73 mRNA and protein than ovarian adenomas.

Adenocarcinoma↗
PubMed2000

Fatal cardiac arrhythmia after infusion of dimethyl sulfoxide-cryopreserved hematopoietic stem cells in a patient with severe primary cardiac amyloidosis and end-stage renal failure.

Amyloidosis (AL) is a rapidly fatal plasma cell dyscrasia causing progressive multiorgan failure. Recently, substantial improvement of survival was reported following high-dose chemotherapy with peripheral blood stem cell (PBSC) rescue. We describe a patient with AL with severe cardiac and renal involvement who received high-dose melphalan followed by fractioned autologous PBSC transplantation (455 ml on day 1 and 350 ml on day 2). Immediately after the second infusion of the PBSCs, life-threatening cardiac arrhythmias occurred and, despite intensive treatment, the patient died less than 24 h later. The infusion of cryopreserved PBSCs may be associated with complications, including cardiac toxicity. Dimethyl sulfoxide (DMSO) is the most frequently used cryopreservation agent. In the present case, we suggest that DMSO could have played an important role in causing the fatal cardiac arrhythmias. The mechanisms of the cardiovascular effects of DMSO and the possible preventive measures are discussed. Given the poor prognosis of AL and the promising results of dose-intensive chemotherapy with autologous PBSC transplantation, careful patient selection and intensive monitoring are mandatory in order to further pursue this therapeutic approach.

Amyloidosis↗
PubMed2000

Interleukin-8 expression by fetal and neonatal pulmonary cells in hyaline membrane disease and amniotic infection.

IL-8, a chemokine with striking neutrophil-activating properties, is important in the pathogenesis of various disorders of the adult lung. Little is known about its production and possible role in fetal and neonatal lung disorders. We therefore examined IL-8 expression by immunohistochemistry in lung tissue from neonates with hyaline membrane disease, from fetuses with amniotic infection, and from a fetal control group with noninflammatory diseases. In the majority of cases with hyaline membrane disease, intense IL-8 immunoreaction was seen in fetal and neonatal neutrophils and in almost half of these cases, in epithelial cells of the terminal airways as well as in the connective tissue cell compartment. In contrast, in the amniotic infection group, strong IL-8 immunostaining was almost exclusively seen in maternal aspirated neutrophils. Little or no IL-8 signal was seen in the control cases in all cell types examined. Also, no IL-8 production by fetal lung cells was detected in fetuses <18 wk of gestation. The marked presence of IL-8 in all cell types of the lung in hyaline membrane disease cases indicates a role for IL-8 in the pathobiology of hyaline membrane disease possibly similar to that in adult respiratory distress syndrome. It further suggests that the cytokine network of the fetal lung is already well developed by the second trimester of pregnancy.

Adult↗
PubMed2000

Divergent expression of cyclin-dependent kinase inhibitors (CKI) and p14ARF/p16 beta in non-Hodgkin's lymphomas and chronic lymphocytic leukemia.

Chronic B-cell lymphocytic leukaemia (CLL) and low-grade B-cell Non Hodgkin's lymphomas (Lg-NHL) are characterized by slow accumulation of neoplastic cells arrested in the G0/G1 phase of the cell cycle. In contrast, proliferation rates are high in aggressive B-cell lymphomas (Hg-NHL). Divergent expression of cyclin-dependent kinase inhibitors (CKI) in the cell cycle may contribute to these differences. We analysed CLL as well as low and high grade B-cell NHL for expression of G1-specific and universal CKI by competitive RT-PCR and immunostaining. p16(INK4A) expression was low in all types of neoplasms. Highest p14(ARF) /p16 beta expression levels were found in normal lymphocytes. Expression of this CKI was significantly lower in CLL, but still higher in CLL than in the lymphomas (median 27 vs. 3 mRNA transcripts x 10(3), p = 0.0001). p14(ARF) /p16 beta immunostaining correlated with mRNA expression. Highest p21 mRNA levels were found in CLL, but three of four CLL with abundant p21 mRNA production were negative on immunostaining. High grade lymphomas showed markedly decreased p21 expression (3.9 in Hg-NHL vs. 12 in Lg-NHL and 29 in CLL; values expressed as mRNA transcripts x 10(3), p < 0.009). mRNA and protein expression of p27 was considerably higher in CLL than in the lymphomas. Differential CKI expression in various B-cell neoplasias may provide important biological markers, if not the molecular underpinning of their different cell cycle kinetics. Targeted interference with such genes governing cell cycle control in lymphoid neoplasia may pave the way towards new treatment strategies.

Adult↗
PubMed1999

Interferon-alpha before allogeneic bone marrow transplantation in chronic myelogenous leukemia does not affect outcome adversely, provided it is discontinued at least 90 days before the procedure.

The influence of interferon-alpha (IFN) pretreatment on the outcome after allogeneic bone marrow transplantation (BMT) in chronic myelogenous leukemia (CML) is controversial. One goal of the German randomized CML Studies I and II, which compare IFN +/- chemotherapy versus chemotherapy alone, was the analysis of whether treatment with IFN as compared to chemotherapy had an influence on the outcome after BMT. One hundred ninety-seven (23%) of 856 Ph/bcr-abl-positive CML patients were transplanted. One hundred fifty-two patients transplanted in first chronic phase were analyzed: 86 had received IFN, 46 hydroxyurea, and 20 busulfan. Forty-eight patients (32%) had received transplants from unrelated donors. Median observation time after BMT was 4.7 (0.7 to 13.5) years. IFN and chemotherapy cohorts were compared with regard to transplantation risks, duration of treatments, interval from discontinuation of pretransplant treatment to BMT, conditioning therapy, graft-versus-host disease prophylaxis and risk profiles at diagnosis and transplantation, and IFN cohorts also with regard to performance and resistance to IFN. Outcome of patients receiving related or unrelated transplants pretreated with IFN, hydroxyurea, or busulfan was not significantly different. Five-year survival after transplantation was 58% for all patients (57% for IFN, 60% for hydroxyurea and busulfan patients). The outcome within the IFN group was not different by duration of prior IFN therapy more or less than 5 months, 1 year, or 2 years. In contrast, a different impact was observed in IFN-pretreated patients depending on the time of discontinuation of IFN before transplantation. Five-year survival was 46% for the 50 patients who received IFN within the last 90 days before BMT and 71% for the 36 patients who did not (P =.0057). Total IFN dosage had no impact on survival after BMT. We conclude that outcome after BMT is not compromised by pretreatment with IFN if it is discontinued at least 3 months before transplantation. Clear candidates for early transplantation should not be pretreated with IFN.

Adolescent↗
PubMed1999

Distinct expression patterns of the p53-homologue p73 in malignant and normal hematopoiesis assessed by a novel real-time reverse transcription-polymerase chain reaction assay and protein analysis.

The role of the recently identified first p53-homologue, p73, in neoplastic transformation is unknown. To elucidate p73 gene expression in hematopoiesis, we investigated samples from chronic myeloid leukemia (CML) and acute myeloid leukemia patients, leukemia cell lines, as well as mature and immature normal hematopoietic cells by real-time quantitative RT-PCR and Western blot analysis. We found a distinct p73 expression profile with highest p73 mRNA transcript levels in hematopoietic malignancies such as CML blast crisis and acute myelogenous leukemia versus CML chronic phase and normal controls. Mono- and biallelic p73 expression was found in both normal and malignant hematopoiesis. p73 protein was expressed at various levels in leukemia samples and cell lines but could not be detected in any normal controls tested. Our results point to a distinct yet undefined role of p73 in the pathogenesis of myeloid neoplasms.

Alleles↗
PubMed1999

Cloning and analysis of the gene for the human puromycin-sensitive aminopeptidase.

The gene encoding the human puromycin-sensitive aminopeptidase (PSA) has been cloned and characterized. The human PSA gene is composed of 23 exons and 22 introns and spans approximately 40 kb of chromosome 17 at the interval 17q12-21. An analysis of the 5' end of the human PSA transcript reveals that the translational start site corresponds to nt 210 of the human PSA cDNA, as suggested by RT-PCR, 5' RACE, and computer analysis of expressed sequence tags. A comparison of the exon/exon boundaries of the human PSA gene with those of the human aminopeptidase N (APN) gene shows little conservation, suggesting that the two genes, which are closely related in protein sequence, diverged early during evolution.

Amino Acid Sequence↗
PubMed1999

Aberrant FHIT mRNA transcripts are present in malignant and normal haematopoiesis, but absence of FHIT protein is restricted to leukaemia.

Aberrant FHIT mRNA transcripts are present in malignant and normal haematopoiesis, but absence of FHIT protein is restricted to leukaemia Alterations of the recently cloned fragile histidine triad (FHIT) gene at chromosome 3p14.2 are frequent in a variety of solid tumours and cancer cell lines. Based on these findings, FHIT has been proposed as a putative tumour-suppressor gene. We evaluated the mRNA expression of the FHIT gene in samples from 55 patients with various haematological malignancies (21 AML, 8 CML, 10 CLL, seven low-grade and nine high-grade Non-Hodgkin's lymphomas), in a panel of 16 leukaemia cell lines, in normal mature haematopoietic cells of both myeloid and lymphoid lineage, as well as in CD34+ haematopoietic progenitor cells. Aberrant FHIT mRNA transcripts were observed in 14/16 (88%) leukaemia cell lines, 43/55 (78%) primary haematological neoplasms, but also in 17/22 (77%) normal controls. 1/16 (6%) cell lines and 7/55 (13%) neoplasms did not express any FHIT mRNA. cDNA sequencing revealed exonic deletions, small DNA insertions and combinations of both. Analysis of genomic DNA showed gene deletions in two myeloid leukaemia cell lines. In contrast to all normal types of haematopoietic cells, FHIT protein was clearly reduced or absent in 8/18 (44%) neoplastic samples tested. Our data indicate that whilst aberrant FHIT mRNA transcripts are seen both in normal and malignant cells, lack of FHIT protein is restricted to leukaemia. Absent FHIT protein expression might contribute to leukaemogenesis.

Acid Anhydride Hydrolases↗
PubMed1999

Cytosine demethylation of the proteinase-3/myeloblastin primary granule protease gene during phagocyte development.

Proteinase-3/Myeloblastin (Mbn) is a neutral serine protease and a major constituent of the primary granules of myeloid cells. It can degrade extracellular matrix proteins and has been discussed as a key factor for the initiation of terminal differentiation in promyelocytic cells. Regulation of Mbn closely parallels that of another major primary granule protein, myeloperoxidase (MPO). We examined the expression and DNA methylation of Mbn in a model of in vitro differentiation of CD34+ enriched peripheral blood progenitor cells (PBPCs), and in various other myeloid and non-myeloid tissues. Mbn mRNA was undetectable in uncultured PBPCs but was upregulated during their in vitro differentiation. Its expression was enhanced in the presence of G-CSF. Mbn expression was also detected in several myeloid cell lines but not in mature granulocytes, monocytes and macrophages. Partial demethylation at a CpG site within Mbn intron 1 (analyzed by restriction with SmaI) was observed during continued in vitro differentiation of PBPCs. This site was fully demethylated in mature granulocytes, monocytes and macrophages. Variable methylation of this site and a second SmaI site located upstream of the putative Mbn promoter region was present in other myeloid and non-myeloid tissues examined.

Cell Differentiation↗
PubMed1999

Severe inclusion body beta-thalassaemia with haemolysis in a patient double heterozygous for beta(0)-thalassaemia and quadruplicated alpha-globin gene arrangement of the anti-4.2 type.

We describe a new case of an association of alpha-globin gene quadruplication of the anti-4.2 type with beta(0)-thalassaemia. The patient, a young woman of mixed Brazilian-Portuguese origin, suffered from chronic haemolytic anaemia with splenomegaly. Bone marrow supravital staining with brilliant cresyl blue and electron microscopy studies showed large inclusion bodies in about 3% of erythroblasts. Upon immunofluorescent staining these inclusions reacted with a monoclonal antibody to alpha- but not to beta-globin. Analysis of alpha-globin cluster by Southern blotting showed the presence of pathologic fragments specific for the anti-4.2 alpha-globin gene quadruplication. Alpha/beta mRNA ratio was higher than in cases combining alpha-globin triplication and beta(0)-thalassaemia or in cases of beta(0)-thalassaemia heterozygous state alone (18, 14.7 and 10.1 respectively). Our data confirmed the hypothesis that the clinically detectable haemolysis in this beta(0)-thalassaemic patient was due to an unusually high amount of precipitated alpha-globin in erythroid precursors. This considerable excess of alpha-globin chains was due partly to the beta-globin deficit caused by the presence of the beta(0)-thalassaemic gene, but also to the presence of 6 active alpha-globin genes resulting from alpha-globin gene quadruplication in one chromosome.

Anemia, Hemolytic↗
PubMed1999

The cyclin-dependent kinase inhibitors p18INK4c and p19INK4d are highly expressed in CD34+ progenitor and acute myeloid leukaemic cells but not in normal differentiated myeloid cells.

Cyclin-dependent kinase inhibitors (CKIs) are important for the differentiation of cells in various tissues. In acute myeloid leukaemia (AML) the cells accumulate at particular stages of myeloid maturation. We therefore analysed the expression pattern of different CKIs in fresh samples of AML patients and compared it with that in CD34+ progenitor and normal differentiated myeloid cells. Competitive RT-PCR and Western analysis revealed a significantly higher expression of p18INK4c and p19INK4d in leukaemic and CD34+ progenitor cells than in granulocytes and monocytes. A different pattern was seen for p27Kip1 and p57Kip2 expression being low in leukaemic cells but high in normal immature and differentiated cells. No marked differences were found in p15INK4b and p21Cip1 mRNA expression between leukaemic and CD34+ progenitor or mature myeloid cells. Our findings therefore indicate that high expression of p18INK4c and p19INK4d in haemopoietic progenitor and leukaemic blast cells may contribute to the premature differentiation block seen in AML.

Acute Disease↗
PubMed1999

A novel BCR-ABL transcript e2a2 in a chronic myelogenous leukaemia patient with a duplicated Ph-chromosome and monosomy 7.

A novel BCR-ABL transcript was detected by multiplex RT-PCR in a patient with Philadelphia chromosome (Ph) positive chronic myelogenous leukaemia (CML) in accelerated phase. Sequencing of the aberrant transcript revealed an in-frame e2a2 fusion that included a 9 basepairs insertion. Cytogenetic analysis showed t(9;22), an additional Ph chromosome and monosomy 7. The clinical course was dismal: therapy was poorly tolerated, and the patient died in blast crisis 10 months after diagnosis. These data support the association of additional Ph and monosomy 7 with poor prognosis and suggest that the novel e2a2 BCR-ABL transcript may be related to an aggressive clinical course.

Aged↗
PubMed1999

In childhood acute lymphoblastic leukemia the hypophosphorylated retinoblastoma protein, p110RB, is diminished, as compared with normal CD34+ peripheral blood progenitor cells.

Acute lymphoblastic leukemia (ALL) of childhood arises from dysregulated clonal expansion of immature lymphoid precursor cells that fail to differentiate into functional lymphocytes. The cell-cycling status of ALL cells shares many common features with that of normal CD34+ hematopoietic progenitor cells, such as low number of resting G0 and cycling S phase cells even though the growth fraction is high. Thus, ALL cells should be in a long G1 phase. Phosphorylation of the retinoblastoma protein is a crucial step in cell-cycle progression from G0/early G1 to late G1/S phase. We therefore analyzed the G1 distribution of these two immature cell populations by immunostaining and Western blot. Bone marrow samples from children with ALL at diagnosis as well as purified CD34+ cells, before and after in vitro stimulation with cytokines, were investigated for the expression of hypophosphorylated p110RB (early G1 phase), total retinoblastoma protein, statin (G0 phase), bromo-deoxyuridine (S phase), proliferating cell nuclear antigen, and p120 (cycling cells). Compared with unstimulated CD34+ cells (95.8 +/- 1.2%) the component of ALL cells containing hypophosphorylated p110RB (16.3 +/- 13.2%) was significantly reduced (p = 0.00018), whereas only a minor difference could be detected for the proportion of cycling cells (p = 0.03), and no difference in G0 and S phase cells (p > 0.05). Our results indicate that, as opposed to unstimulated CD34+ cells, the majority of ALL cells are beyond the restriction point and therefore irreversible committed to DNA replication and mitosis.

Antigens, CD34↗
PubMed1998

Expression of p16INK4a/p16alpha and p19ARF/p16beta is frequently altered in non-small cell lung cancer and correlates with p53 overexpression.

The CDKN2 locus expresses two different mRNA transcripts, designated alpha and beta. The protein product of the alpha transcript is the cell cycle inhibitor and tumour suppressor p16INK4a. The beta transcript is translated in an alternate reading frame (ARF) and in humans encodes a 15 kDa protein (p19ARF). Immunohistochemical and Western analysis of p16INK4a has shown that the protein is downregulated in a significant number of tumours, but less is known on the expression of the p19ARF. We have examined the expression of p16INK4a and p19ARF in resectable non-small cell lung cancer (NSCLC) by immunostaining (n=49) and multiplex RT-PCR (n=28). In order to investigate the mechanism responsible for p16INK4a downregulation, exon 1alpha methylation was analysed in a PCR-based assay. Of 49 tumours examined by immunostaining, 24 and 20 tumours expressed p16INK4a and p19ARF at nil to low levels, respectively. p19ARF was localized primarily to the nuclei of tumour cells, but was also seen to varying degrees in nuclei of lymphocytes, chondrocytes, fibroblasts, and epithelial cells. No tumour with normal p16INK4a had decreased p19ARF expression. Among 16 tumours with nil to low p16INK4a expression, 11 tumours exhibited full methylation of at least one site within exon 1alpha and these tumours showed normal p19ARF expression. In contrast, no methylation of exon 1alpha was observed in five tumours which also lacked p19ARF. In normal lung, p16INK4a and p19ARF were not expressed at detectable levels, the multiplex RT-PCR results were balanced, and sites within exon 1alpha were strongly methylated. In tumours, imbalanced multiplex RT-PCR data (p16INK4a<p19ARF) predicted methylation of exon 1alpha (P=0.0006) as well as downregulation of p16INK4a. p19ARF downregulation was inversely correlated with p53 overexpression (P=0.025), whilst negative immunostaining for p16INK4a was inversely correlated with pRb down-regulation (P=0.003) and directly correlated with p53 overexpression as assessed by immunostaining (P=0.015). Our results show that: (1) p16INK4a and p19ARF expression are altered in almost half of resectable NSCLC; (2) methylation within exon 1alpha is a frequent, but not the only mechanism of p16INK4a downregulation; and that (3) the inverse association of p19ARF and p53 alteration is consistent with a linked pathway.

Aged↗
PubMed1998

[2-CDA in treatment of hairy cell leukemia: a comparison between intravenous and subcutaneous administration. Swiss Study Group of Applied Cancer Research].

2-chlorodeoxyadenosine (2-CDA) is very effective in the treatment of patients with hairy-cell leukaemia, with an overall response rate of 80-95%. The standard treatment is a continuous intravenous infusion for 7 days. The bioavailability of 2-CDA after subcutaneous injection is 100%, but the concentration-time profile is completely different compared to continuous intravenous administration. In the present study we compared the intravenous standard treatment (group 1, n = 22; 0.1 mg/kg/d for 7 days, civ.) with subcutaneous administration of 2-CDA (group 2, n = 62; 0.14 mg/kg/d for 5 days, s.c.) in patients with hairy-cell leukaemia. In group 1, 96% (21/22) of patients responded to 2-CDA (complete remission 73%, partial remission 23%) and in the second group 97% were responsive (complete response 76%, 47/62; partial remission 21%, 13/62). The percentage for moderate and severe infections in the trial with intravenous and subcutaneous treatment was 14% and 26% respectively (p = 0.37). We conclude that subcutaneous administration of 2-CDA in patients with hairy-cell leukaemia is feasible and economical and results in comparable responses and toxicity compared to the intravenous standard treatment.

2-Chloroadenosine↗
PubMed1998

[HemoSurf--an interactive hematology atlas on the world wide web].

Microscopic examination of blood films is essential in clinical medicine despite automatic cell counters. To acquire this skill takes time, an adequate technical infrastructure and experienced instructors. In many cases all these things are not readily available. A computer-based learning program such as "HemoSurf" helps to supply these needs. In its learning part, "HemoSurf" allows the user to develop pattern recognition by offering more than 2000 images of blood and bone marrow films. In a stepwise manner the learner is enabled to differentiate leukocytes and recognize qualitative alterations to blood cells. In the reference part the user can look up blood films and some of the corresponding bone marrow films of over 30 diseases. In the World Wide Web "HemoSurf" is accessible via the following URL: [http./(/)www.aum.iawf.unibe.ch/VLZ/ BWL/HemoSurf/Index.htm]. A publication on CD-ROM with different language versions is in preparation.

Blood Cells↗