Multi-color polymer pen lithography for oligonucleotide arrays

Multi-color patterning by polymer pen lithography (PPL) was used to fabricate covalently immobilized fluorophore and oligonucleotide arrays with up to five different components. These can easily be translated for presentation of multiple protein types to a single cell.

Hematopoietic stem cell transplantation for advanced myelodysplastic syndrome in children: results of the EWOG-MDS 98 study

We report on the outcome of children with advanced primary myelodysplastic syndrome (MDS) transplanted from an HLA-matched sibling (MSD) or an unrelated donor (UD) following a preparative regimen with busulfan, cyclophosphamide and melphalan. Ninety-seven patients with refractory anemia with excess blasts (RAEB, n=53), RAEB in transformation (RAEB-T, n=29) and myelodysplasia-related acute myeloid leukemia (MDR-AML, n=15) enrolled in the European Working Group of MDS in Childhood (EWOG-MDS) 98 study and given hematopoietic stem cell transplantation (HSCT) were analyzed. Median age at HSCT was 11.1 years (range 1.4-19.0). Thirty-nine children were transplanted from an MSD, whereas 58 were given the allograft from a UD (n=57) or alternative family donor (n=1). Stem cell source was bone marrow (n=69) or peripheral blood (n=28). With a median follow-up of 3.9 years (range 0.1-10.9), the 5-year probability of overall survival is 63%, while the 5-year cumulative incidence of transplantation-related mortality (TRM) and relapse is 21% each. Age at HSCT greater than 12 years, interval between diagnosis and HSCT longer than 4 months, and occurrence of acute or extensive chronic graft-versus-host disease were associated with increased TRM. The risk of relapse increased with more advanced disease. This study indicates that HSCT following a myeloablative preparative regimen offers a high probability of survival for children with advanced MDS.

A novel HLA-C allele, HLA-Cw*06:20

A novel HLA-C allele, HLA-Cw*06:20 differs from HLA-Cw*06:02 by one nucleotide exchange.

Rhabdomyosarcoma in patients with constitutional mismatch-repair-deficiency syndrome

BACKGROUND

Biallelic germline mutations in the mismatch repair genes MLH1, MSH2, MSH6 or PMS2 cause a recessive childhood cancer syndrome characterised by early-onset malignancies and signs reminiscent of neurofibromatosis type 1 (NF1). Alluding to the underlying genetic defect, we refer to this syndrome as constitutional mismatch repair-deficiency (CMMR-D) syndrome. The tumour spectrum of CMMR-D syndrome includes haematological neoplasias, brain tumours and Lynch syndrome-associated tumours. Other tumours, such as neuroblastoma, Wilm tumour, ovarian neuroectodermal tumour or infantile myofibromatosis, have so far been found only in individual cases.

RESULTS

We analysed two consanguineous families that had members with suspected CMMR-D syndrome who developed rhabdomyosarcoma among other neoplasias. In the first family, we identified a pathogenic PMS2 mutation for which the affected patient was homozygous. In family 2, immunohistochemistry analysis showed isolated loss of PMS2 expression in all tumours in the affected patients, including rhabdomyosarcoma itself and the surrounding normal tissue. Together with the family history and microsatellite instability observed in one tumour this strongly suggests an underlying PMS2 alteration in family 2 also.

CONCLUSION

Together, these two new cases show that rhabdomyosarcoma and possibly other embryonic tumours, such as neuroblastoma and Wilm tumour, belong to the tumour spectrum of CMMR-D syndrome. Given the clinical overlap of CMMR-D syndrome with NF1, we suggest careful examination of the family history in patients with embryonic tumours and signs of NF1 as well as analysis of the tumours for loss of one of the mismatch repair genes and microsatellite instability. Subsequent mutation analysis will lead to a definitive diagnosis of the underlying disorder.

Pyoderma Gangraenosum, a Rare, but Potentially Fatal Complication in Paediatric Oncology Patients

Pyoderma gangraenosum (PG) is a serious chronic, ulcerative skin disorder afflicting both adults and children. As PG is often associated with systemic diseases (>50%) such as inflammatory bowel disease, rheumatoid arthritis or haematological disorders, it requires a multidisciplinary approach. This disorder is not commonly reported in paediatrics; therefore children with PG represent a particularly difficult diagnostic challenge. Clinical diagnosis is often delayed and PG is only considered after eliminating other causes of cutaneous ulcers. We report a 4-year-old boy with secondary myelodysplastic syndrome following treatment for acute lymphoblastic leukaemia who presented with a massive inflammatory, ulcerative proliferation of the lower lip which was diagnosed as PG. We have reviewed the literature with reference to diagnostic criteria and treatment options of this disorder that is particularly rare in childhood.

Reduced intensity conditioning in unrelated donor transplantation for refractory cytopenia in childhood

Myelodysplastic syndromes (MDS) are a heterogenous group of acquired hematopoietic stem cell disorders. Refractory cytopenia (RC) is the most common subtype of childhood MDS and hematopoietic stem cell transplantation (HSCT) is the only curative treatment. HSCT following a myeloablative preparative regimen is associated with a low probability of relapse and considerable transplant-related mortality. In the present European Working Groups of MDS pilot study, we investigated whether a reduced intensity conditioning regimen (RIC) is able to offer reduced toxicity without increased rates of graft failure or relapse. Nineteen children with RC were transplanted from an unrelated donor following RIC consisting of fludarabine, thiotepa and anti-thymocyte globulin. Three patients experienced graft failure. Neutrophil and platelet engraftment occurred at a median time of 23 and 30 days, respectively. Cumulative incidence of grade II-IV and grade III and IV acute graft-versus-host disease (GVHD) was 0.48 and 0.13, respectively; three patients developed extensive chronic GVHD. Although infections were the predominant complications, only one patient with extensive chronic GVHD died from infectious complications. Overall and event-free survival at 3 years were 0.84 and 0.74, respectively. In conclusion, our results were comparable to those of patients treated with myeloablative HSCT. Long-term follow-up is needed to demonstrate the expected reduction in long-term sequelae.

Genome-wide single-nucleotide polymorphism analysis in juvenile myelomonocytic leukemia identifies uniparental disomy surrounding the NF1 locus in cases associated with neurofibromatosis but not in cases with mutant RAS or PTPN11

Juvenile myelomonocytic leukemia (JMML) is a malignant hematopoietic disorder whose proliferative component is a result of RAS pathway deregulation caused by somatic mutation in the RAS or PTPN11 oncogenes or in patients with underlying neurofibromatosis type 1 (NF-1), by loss of NF1 gene function. To search for potential collaborating genetic abnormalities, we used oligonucleotide arrays to analyse over 116 000 single-nucleotide polymorphisms across the genome in 16 JMML samples with normal karyotype. Evaluation of the SNP genotypes identified large regions of homozygosity on chromosome 17q, including the NF1 locus, in four of the five samples from patients with JMML and NF-1. The homozygous region was at least 55 million base pairs in each case. The genomic copy number was normal within the homozygous region, indicating uniparental disomy (UPD). In contrast, the array data provided no evidence for 17q UPD in any of the 11 JMML cases without NF-1. We used array-based comparative genomic hybridization to confirm 17q disomy, and microsatellite analysis was performed to verify homozygosity. Mutational analysis demonstrated that the inactivating NF1 lesion was present on both alleles in each case. In summary, our data indicate that a mitotic recombination event in a JMML-initiating cell led to 17q UPD with homozygous loss of normal NF1, provide confirmatory evidence that the NF1 gene is crucial for the increased incidence of JMML in NF-1 patients, and corroborate the concept that RAS pathway deregulation is central to JMML pathogenesis.

Polymyositis--an unusual presentation of cGvHD in children

Polymyositis is a rare manifestation of cGvHD in adult patients following allogeneic BMT. Here, we report on a 2.1-yr-old girl who presented with a facial swelling and rapidly developing respiratory failure eight months after BMT for severe combined immunodeficiency. Possible infectious agents and autoimmune origin other than cGvHD were excluded. The girl responded promptly to steroid therapy and remains well without other signs of cGvHD four months later.

Gene transfer of SHIP-1 inhibits proliferation of juvenile myelomonocytic leukemia cells carrying KRAS2 or PTPN11 mutations

Juvenile myelomonocytic leukemia (JMML) is a malignant disease of early childhood characterized by a hypersensitivity to granulocyte/macrophage colony-stimulating factor (GM-CSF). Mutations in RAS or PTPN11 are frequently detected in JMML patients. The SH2-containing inositol 5-phosphatase 1 (SHIP-1) is a negative regulator of GM-CSF signaling, and inactivation of SHIP-1 in mice results in a myeloproliferative disease. Here, we report the effects of SHIP-1 expression on GM-CSF-dependent proliferation and colony formation of human hematopoietic cells. After retroviral-mediated transduction of SHIP-1 into CD34+ cells from cord blood of healthy newborns or peripheral blood of JMML patients carrying mutations in KRAS2 or PTPN11, we observed a reduction in GM-CSF-dependent proliferation and colony formation. An enzymatically inactive form of SHIP-1 (D672A) had no effect. These data indicate that SHIP-1 can effectively block GM-CSF hypersensitivity in JMML progenitor cells with mutations in KRAS2 or PTPN11 and may be a useful approach for the treatment of JMML patients.

Donor leukocyte infusion after hematopoietic stem cell transplantation in patients with juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a clonal myeloproliferative disorder of early childhood. In all, 21 patients with JMML who received donor leukocyte infusion (DLI) after allogeneic hematopoietic stem cell transplantation (HSCT) for either mixed chimerism (MC, n=7) or relapse (n=14) were studied. Six patients had been transplanted from an HLA-matched sibling and 15 from other donors. Six of the 21 patients (MC: 3/7 patients; relapse: 3/14 patients) responded to DLI. Response rate was significantly higher in patients receiving a higher total T-cell dose (> or =1 x 10(7)/kg) and in patients with an abnormal karyotype. None of the six patients receiving DLI from a matched sibling responded. Response was observed in five of six patients who did and in one of 15 children who did not develop acute graft-versus-host disease following DLI (P=0.01). The overall outcome was poor even for the responders. Only one of the responders is alive in remission, two relapsed, and three died of complications. In conclusion, this study shows that some cases of JMML may be sensitive to DLI, this providing evidence for a graft-versus-leukemia effect in JMML. Infusion of a high number of T cells, strategies to reduce toxicity, and cytoreduction prior to DLI may improve the results.

Evaluation of dysplastic features in myelodysplastic syndromes: experience from the morphology group of the European Working Group of MDS in Childhood (EWOG-MDS)

In the absence of genetic abnormalities, the diagnoses of myelodysplastic syndromes (MDS) is primarily based on the presence of dysplasia in blood and marrow cells. Currently, there is no standardized approach to evaluate dysplasia. International cooperative study groups like the European Working Group on MDS in Childhood (EWOG-MDS) depend, however, on a concordance in diagnoses by their national reference centres for morphology. In EWOG-MDS, the morphological diagnoses of all cases enrolled from Scandinavia, the Netherlands, Germany, the Czech Republic, Austria and Italy are established by five experienced pathologists or hematologists cooperating in a morphology board. To study their concordance in evaluating myelodysplastic disorders, members of the morphology board initiated blinded reviews of smears of blood and bone marrow aspirates of known cases. Four features of dysplasia in granulopoiesis, erythropoiesis and megakaryopoiesis were assessed on May-Grünwald-Giemsa stained smears. In a final review of six blinded cases, good concordance for these features was achieved among the five observers. Accurately defined and restrictively applied cellular features of dysplasia are an important tool to improve and ensure the concordance in the diagnosis of MDS among investigators. For cooperative groups, agreement on the evaluation of the morphological assessment of dysplasia is a prerequisite.

Stem cell transplantation for aplastic anemia and myelodysplastic syndrome

SUMMARY

Stem cell transplantation (SCT) from a histocompatible sibling is treatment of choice for severe aplastic anemia. Survival rates have been reported to be as high as 90% for children. Immunosuppressive therapy (IST) is employed in patients who are not candidates for SCT due to donor unavailability. The addition of cyclosporin A to antilymphocyte globulin has improved the response rate to 70-80%, and survival at 5 years among responders is about 90%. In all, 30% of patients treated by IST suffer from relapse, but long-term prognosis does not appear to be affected by this complication. Juvenile myelomonocytic leukemia (JMML) shares both myelodysplastic and myeloproliferative features. Survival (10-year) of patients with JMML without SCT is only 6%. Children with JMML should be transplanted early in the course of their disease. Conditioning regimen composed of three alkylating agents, busulfan, cyclophosphamide and melphalan has been favored by the EWOG-MDS and EBMT-Pediatric WP in the second half of the 1990s. SCT using this conditioning regimen is capable of curing approximately 50% of patients with JMML. More than 70% of patients with refractory cytopenia and more than 50% of children with advanced MDS are cured of by the early performed allogeneic SCT.

The International Prognostic Scoring System (IPSS) for childhood myelodysplastic syndrome (MDS) and juvenile myelomonocytic leukemia (JMML)

The International Prognostic Scoring System (IPSS) for myelodysplastic syndrome (MDS) is based upon weighted data on bone marrow (BM) blast percentage, cytopenia, and cytogenetics, separating patients into four prognostic groups. We analyzed the value of the IPSS in 142 children with de novo MDS and 166 children with juvenile myelomonocytic leukemia (JMML) enrolled in retro- and prospective studies of the European Working Group on childhood MDS (EWOG-MDS). Survivals in MDS and JMML were analyzed separately. Among the criteria considered by the IPSS score, only BM blasts <5% and platelets >100 x 10(9)/l were significantly associated with a superior survival in MDS. In JMML, better survival was associated with platelets >40 x 10(9)/l, but not with any other IPSS factors including cytogenetics. In conclusion, the IPSS is of limited value in both pediatric MDS and JMML. The results reflect the differences between myelodysplastic and myeloproliferative diseases in children and adults.

Retrospektive Analyse des klinischen Verlaufs bei 12 Kindern mit der Verdachtsdiagnose einer essenziellen Thrombozythämie

BACKGROUND

Essential Thrombocythemia (ET) is an acquired myeloproliferative disorder (MPD) characterized by excessive production of platelets. The disorder is usually affecting adults and is rarely diagnosed in children.

PATIENTS AND METHODS

In this retrospective study we describe 12 children aged 5-16 years in whom ET was presumed.

RESULTS

Median follow-up was 59 months (range 10-72). At diagnosis 7 patients had clinical symptoms (syncope, poor concentration, fatigue, abdominal pain and mild bleeding), 5 patients were diagnosed accidentally (operation, allergy, enuresis, pneumonia, routine examination). Median platelet count at diagnosis was 1 325 x 10 (9)/L (range 600-3 050). In 11 cases bone marrow morphology was consistent with ET, one patient had chronic idiopathic myelofibrosis. Cytogenetics were normal in all studied cases. Within 6 months after the initial presentation one patient who was diagnosed accidentally developed thrombosis, another patient had mild bleeding. 8 patients were treated with acetylsalicylic acid (in addition, 1 patient received hydroxyurea, 2 patients received anagrelide). On last follow-up all patients were alive, none had developed leukemia. 5 patients experienced hematological remission. 2 of these children had not received any therapy.

CONCLUSIONS

Many patients had symptoms attributable to ET. The clinical course is heterogeneous with complete normalization of platelets in the absence of cytoreductive therapy in some children. Due to the low incidence of ET in children indications for therapy are unclear and can only be deduced from findings obtained from studies in adults.

Semi-synthetic DNA–protein conjugates: novel tools in analytics and nanobiotechnology

This article reports on the syntheses, characterization and applications of semi-synthetic conjugates composed of nucleic acids, proteins and inorganic nanoparticles. For example, self-assembled oligomeric networks consisting of streptavidin and double-stranded DNA are applicable as reagents in immunoassays, model systems for ion-switchable nanoparticle networks as well as nanometer-scaled ‘soft material’ standards for scanning probe microscopy. Covalent conjugates of single-stranded DNA and streptavidin are utilized as biomolecular adapters for the immobilization of biotinylated macromolecules at solid substrates via nucleic acid hybridization. This ‘DNA-directed immobilization’ allows for reversible and site-selective functionalization of solid substrates with metal and semiconductor nanoparticles or, vice versa, for the DNA-directed functionalization of gold nanoparticles with proteins, such as immunoglobulins and enzymes. This approach is applicable for the detection of chip-immobilized antigens. Moreover, covalent DNA–protein conjugates allow for their selective positioning along single-stranded nucleic acids, and thus for the construction of nanometre-scale assemblies composed of proteins and/or nanoclusters. Examples include the fabrication of functional biometallic nanostructures from gold nanoparticles and antibodies, applicable as diagnostic tools in bioanalytics.

A pediatric approach to the WHO classification of myelodysplastic and myeloproliferative diseases

Myelodysplastic and myeloproliferative disorders are rare in childhood and there is no widely accepted system for their diagnosis and classification. We propose minimal diagnostic criteria and a simple classification scheme which, while based on accepted morphological features and conforming with the recent suggestions of the WHO, allows for the special problems of myelodysplastic diseases in children. The classification recognizes three major diagnostic groups: (1) juvenile myelomonocytic leukemia (JMML), previously named chronic myelomonocytic leukemia (CMML) or juvenile chronic myeloid leukemia (JCML); (2) myeloid leukemia of Down syndrome, a disease with distinct clinical and biological features, encompassing both MDS and AML occurring in Down syndrome; and (3) MDS occurring both de novo and as a complication of previous therapy or pre-existing bone marrow disorder (secondary MDS). The main subtypes of MDS are refractory cytopenia (RC) and refractory anemia with excess of blasts (RAEB). It is suggested retaining the subtype of RAEB-T with 20-30% blasts in the marrow until more data are available. Cytogenetics and serial assessments of the patients are essential adjuncts to morphology both in diagnosis and classification.

Nanostructured dna-protein aggregates consisting of covalent oligonucleotide-streptavidin conjugates

Covalent conjugates consisting of streptavidin and a 24-mer single-stranded DNA oligonucleotide have been oligomerized by cross-linking with a 5',5'-bis-biotinylated 169-base-pair double-stranded DNA (dsDNA) fragment. The oligomeric conjugates formed have been analyzed by nondenaturing gel electrophoresis and scanning-force microscopy (SFM). The comparison of analogous oligomers, prepared from native STV and the bis-biotinylated dsDNA fragment, revealed that the covalent STV-oligonucleotide hybrid conjugates self-assemble to generate oligomeric aggregates of significant smaller size, containing on average only about 2.5 times less dsDNA fragments per aggregate. Likely, this is a consequence of electrostatic or steric repulsion between the dsDNA and the single-stranded oligomer covalently attached to the hybrid, as indicated from control experiments. Nevertheless, the single-stranded oligonucleotide moiety within the oligomeric conjugates can be used as a selective molecular handle for further functionalization and manipulation. For instance, it was used for specific DNA-directed immobilization at a surface, previously functionalized with complementary capture oligonucleotides. Moreover, we demonstrate that macromolecules, such as STV and antibody molecules, which are tagged with the complementary oligonucleotide, specifically bind to the supramolecular DNA-STV oligomeric conjugates. This leads to a novel class of functional DNA-protein conjugates, suitable, for instance, as reagents in immuno-PCR or as building blocks in molecular nanotechnology.

Semi-synthetic nucleic acid-protein conjugates: applications in life sciences and nanobiotechnology

Semi-synthetic conjugates of nucleic acids and proteins can be generated by either covalent coupling chemistry, or else by non-covalent biomolecular recognition systems, such as receptor-ligands of complementary nucleic acids. These nucleic acid-protein conjugates are versatile molecular tools which can be applied, for instance, in the self-assembly of high-affinity reagents for immunological detection assays, the fabrication of laterally microstructured biochips containing functional biological groups, and the biomimetic 'bottom-up' synthesis of nanostructured supramolecular devices. This review summarizes the current state-of-the-art synthesis and characterization methods of artificial nucleic acid-protein conjugates, as well as applications and perspectives for future developments of such hybrid biomolecular components in life sciences and nanobiotechnology.