Determinants of lenalidomide response with or without erythropoiesis-stimulating agents in myelodysplastic syndromes: the HOVON89 trial

A randomized phase-II study was performed in low/int-1 risk MDS (IPSS) to study efficacy and safety of lenalidomide without (arm A) or with (arm B) ESA/G-CSF. In arm B, patients without erythroid response (HI-E) after 4 cycles received ESA; G-CSF was added if no HI-E was obtained by cycle 9. HI-E served as primary endpoint. Flow cytometry and next-generation sequencing were performed to identify predictors of response. The final evaluation comprised 184 patients; 84% non-del(5q), 16% isolated del(5q); median follow-up: 70.7 months. In arm A and B, 39 and 41% of patients achieved HI-E; median time-to-HI-E: 3.2 months for both arms, median duration of-HI-E: 9.8 months. HI-E was significantly lower in non-del(5q) vs. del(5q): 32% vs. 80%. The same accounted for transfusion independency-at-week 24 (16% vs. 67%), but similar in both arms. Apart from presence of del(5q), high percentages of bone marrow lymphocytes and progenitor B-cells, a low number of mutations, absence of ring sideroblasts, and SF3B1 mutations predicted HI-E. In conclusion, lenalidomide induced HI-E in patients with non-del(5q) and del(5q) MDS without additional effect of ESA/G-CSF. The identified predictors of response may guide application of lenalidomide in lower-risk MDS in the era of precision medicine. (EudraCT 2008-002195-10).

Good manufacturing practice production of CD34+ progenitor-derived NK cells for adoptive immunotherapy in acute myeloid leukemia

Allogeneic natural killer (NK) cell-based immunotherapy is a promising, well-tolerated adjuvant therapeutic approach for acute myeloid leukemia (AML). For reproducible NK cell immunotherapy, a homogenous, pure and scalable NK cell product is preferred. Therefore, we developed a good manufacturing practice (GMP)-compliant, cytokine-based ex vivo manufacturing process for generating NK cells from CD34+ hematopoietic stem and progenitor cells (HSPC). This manufacturing process combines amongst others IL15 and IL12 and the aryl hydrocarbon receptor antagonist StemRegenin-1 (SR1) to generate a consistent and active NK cell product that fits the requirements for NK cell immunotherapy well. The cell culture protocol was first optimized to generate NK cells with required expansion and differentiation capacity in GMP-compliant closed system cell culture bags. In addition, phenotype, antitumor potency, proliferative and metabolic capacity were evaluated to characterize the HSPC-NK product. Subsequently, seven batches were manufactured for qualification of the process. All seven runs demonstrated consistent results for proliferation, differentiation and antitumor potency, and preliminary specifications for the investigational medicinal product for early clinical phase trials were set. This GMP-compliant manufacturing process for HSPC-NK cells (named RNK001 cells) is used to produce NK cell batches applied in the clinical trial 'Infusion of ex vivo-generated allogeneic natural killer cells in combination with subcutaneous IL2 in patients with acute myeloid leukemia' approved by the Dutch Ethics Committee (EudraCT 2019-001929-27).

[Clonal hematopoiesis: a risk factor for leukemia and cardiovascular disease?]

Upon ageing, hematopoietic stem or progenitor cells harboring acquired leukemia-associated mutations may expand clonally and become detectable in peripheral blood. So-called clonal hematopoiesis may be detected in 5-55% of (otherwise healthy) individuals aged ≥ 70 years. Clonal hematopoiesis is associated with a higher risk of developing hematological neoplasms, although most individuals never develop malignant disease. Surprisingly, clonal hematopoiesis is also recognized as a new cardiovascular risk factor. Specific patient categories may be at higher risk for the consequences of clonal hematopoiesis. For future risk stratification, there is a need to distinguish high-risk clonal hematopoiesis from 'physiological' ageing processes. In this article we summarize current knowledge on clonal hematopoiesis and its clinical implications. Given the widespread application of next-generation sequencing in routine diagnostics, multidisciplinary recommendations for clinical management of individuals with detected clonal hematopoiesis should be developed.

IL-15 superagonist N-803 improves IFNγ production and killing of leukemia and ovarian cancer cells by CD34+ progenitor-derived NK cells

Allogeneic natural killer (NK) cell transfer is a potential immunotherapy to eliminate and control cancer. A promising source are CD34 + hematopoietic progenitor cells (HPCs), since large numbers of cytotoxic NK cells can be generated. Effective boosting of NK cell function can be achieved by interleukin (IL)-15. However, its in vivo half-life is short and potent trans-presentation by IL-15 receptor α (IL-15Rα) is absent. Therefore, ImmunityBio developed IL-15 superagonist N-803, which combines IL-15 with an activating mutation, an IL-15Rα sushi domain for trans-presentation, and IgG1-Fc for increased half-life. Here, we investigated whether and how N-803 improves HPC-NK cell functionality in leukemia and ovarian cancer (OC) models in vitro and in vivo in OC-bearing immunodeficient mice. We used flow cytometry-based assays, enzyme-linked immunosorbent assay, microscopy-based serial killing assays, and bioluminescence imaging, for in vitro and in vivo experiments. N-803 increased HPC-NK cell proliferation and interferon (IFN)γ production. On leukemia cells, co-culture with HPC-NK cells and N-803 increased ICAM-1 expression. Furthermore, N-803 improved HPC-NK cell-mediated (serial) leukemia killing. Treating OC spheroids with HPC-NK cells and N-803 increased IFNγ-induced CXCL10 secretion, and target killing after prolonged exposure. In immunodeficient mice bearing human OC, N-803 supported HPC-NK cell persistence in combination with total human immunoglobulins to prevent Fc-mediated HPC-NK cell depletion. Moreover, this combination treatment decreased tumor growth. In conclusion,  N-803 is a promising IL-15-based compound that boosts HPC-NK cell expansion and functionality in vitro and in vivo. Adding N-803 to HPC-NK cell therapy could improve cancer immunotherapy.

COVID-19-Associated Bifacial Weakness with Paresthesia Subtype of Guillain-Barré Syndrome

We report a case of bifacial weakness with paresthesia, a recognized Guillain-Barré syndrome subtype characterized by rapidly progressive facial weakness and paresthesia without ataxia or other cranial neuropathies, which was temporally associated with antecedent coronavirus 2019 (COVID-19). This case highlights a potentially novel but critically important neurologic association of the COVID-19 disease process. Herein, we detail the clinicoradiologic work-up and diagnosis, clinical course, and multidisciplinary medical management of this patient with COVID-19. This case is illustrative of the increasingly recognized but potentially underreported neurologic manifestations of COVID-19, which must be considered and further investigated in this pandemic disease.

C-terminal BRE overexpression in 11q23-rearranged and t(8;16) acute myeloid leukemia is caused by intragenic transcription initiation

Overexpression of the BRE (brain and reproductive organ-expressed) gene defines a distinct pediatric and adult acute myeloid leukemia (AML) subgroup. Here we identify a promoter enriched for active chromatin marks in BRE intron 4 causing strong biallelic expression of a previously unknown C-terminal BRE transcript. This transcript starts with BRE intron 4 sequences spliced to exon 5 and downstream sequences, and if translated might code for an N terminally truncated BRE protein. Remarkably, the new BRE transcript was highly expressed in over 50% of 11q23/KMT2A (lysine methyl transferase 2A)-rearranged and t(8;16)/KAT6A-CREBBP cases, while it was virtually absent from other AML subsets and normal tissues. In gene reporter assays, the leukemia-specific fusion protein KMT2A-MLLT3 transactivated the intragenic BRE promoter. Further epigenome analyses revealed 97 additional intragenic promoter marks frequently bound by KMT2A in AML with C-terminal BRE expression. The corresponding genes may be part of a context-dependent KMT2A-MLLT3-driven oncogenic program, because they were higher expressed in this AML subtype compared with other groups. C-terminal BRE might be an important contributor to this program because in a case with relapsed AML, we observed an ins(11;2) fusing CHORDC1 to BRE at the region where intragenic transcription starts in KMT2A-rearranged and KAT6A-CREBBP AML.

World Small Animal Veterinary Association Renal Pathology Initiative: Classification of Glomerular Diseases in Dogs

Evaluation of canine renal biopsy tissue has generally relied on light microscopic (LM) evaluation of hematoxylin and eosin-stained sections ranging in thickness from 3 to 5 µm. Advanced modalities, such as transmission electron microscopy (TEM) and immunofluorescence (IF), have been used sporadically or retrospectively. Diagnostic algorithms of glomerular diseases have been extrapolated from the World Health Organization classification scheme for human glomerular disease. With the recent establishment of 2 veterinary nephropathology services that evaluate 3-µm sections with a panel of histochemical stains and routinely perform TEM and IF, a standardized objective species-specific approach for the diagnosis of canine glomerular disease was needed. Eight veterinary pathologists evaluated 114 parameters (lesions) in renal biopsy specimens from 89 dogs. Hierarchical cluster analysis of the data revealed 2 large categories of glomerular disease based on the presence or absence of immune complex deposition: The immune complex-mediated glomerulonephritis (ICGN) category included cases with histologic lesions of membranoproliferative or membranous patterns. The second category included control dogs and dogs with non-ICGN (glomerular amyloidosis or focal segmental glomerulosclerosis). Cluster analysis performed on only the LM parameters led to misdiagnosis of 22 of the 89 cases-that is, ICGN cases moved to the non-ICGN branch of the dendrogram or vice versa, thereby emphasizing the importance of advanced diagnostic modalities in the evaluation of canine glomerular disease. Salient LM, TEM, and IF features for each pattern of disease were identified, and a preliminary investigation of related clinicopathologic data was performed.

Glomerular Collagen V Codeposition and Hepatic Perisinusoidal Collagen III Accumulation in Canine Collagen Type III Glomerulopathy

Collagen type III glomerulopathy, also known as collagenofibrotic glomerulopathy, is a rare renal disease of unknown pathogenesis. The disease occurs in humans and animals and is characterized by massive glomerular accumulations of collagen type III. In the present study, we describe a Drever dog litter affected by an early onset variant of this glomerular disease, where 4 of 9 puppies developed renal failure within 50 days of age. Necropsy specimens of kidney from the 4 affected cases were studied by light microscopy, electron microscopy, and immunohistochemistry, and characteristic lesions compatible with a diagnosis of collagen type III glomerulopathy were found. In addition, 2 cases showed atypical epithelium in the collecting ducts of the medulla, so-called adenomatoid change. Immunohistochemistry of renal specimens from collagen type III glomerulopathy-affected dogs ( n = 10) originating from two different dog strains, the Drever dogs and a mixed-breed strain, demonstrated that the deposited glomerular collagen is composed of a mixture of collagen III and collagen V. The distribution of the collagen V corresponded to the localization of collagen III; however, differences in staining intensity showed that collagen type III is the dominating component. Immunohistochemistry for collagen III ( n = 9) and a transmission electron microscopic study ( n = 1) showed hepatic perisinusoidal collagen type III deposition in affected cases from both dog strains. This is the first report documenting glomerular accumulations of collagen type V and perisinusoidal liver collagen III deposition in canine collagen type III glomerulopathy.

The Interlaboratory RObustness of Next-generation sequencing (IRON) study: a deep sequencing investigation of TET2, CBL and KRAS mutations by an international consortium involving 10 laboratories

Massively parallel pyrosequencing allows sensitive deep sequencing to detect molecular aberrations. Thus far, data are limited on the technical performance in a clinical diagnostic setting. Here, we investigated as an international consortium the robustness, precision and reproducibility of amplicon next-generation deep sequencing across 10 laboratories in eight countries. In a cohort of 18 chronic myelomonocytic leukemia patients, mutational analyses were performed on TET2, a frequently mutated gene in myeloproliferative neoplasms. Additionally, hotspot regions of CBL and KRAS were investigated. The study was executed using GS FLX sequencing instruments and the small volume 454 Life Sciences Titanium emulsion PCR setup. We report a high concordance in mutation detection across all laboratories, including a robust detection of novel variants, which were undetected by standard Sanger sequencing. The sensitivity to detect low-level variants present with as low as 1-2% frequency, compared with the 20% threshold for Sanger-based sequencing is increased. Together with the output of high-quality long reads and fast run time, we demonstrate the utility of deep sequencing in clinical applications. In conclusion, this multicenter analysis demonstrated that amplicon-based deep sequencing is technically feasible, achieves high concordance across multiple laboratories and allows a broad and in-depth molecular characterization of cancer specimens with high diagnostic sensitivity.

End-Stage Kidney Disease Probably due to Reflux Nephropathy with Segmental Hypoplasia (Ask-Upmark Kidney) in Young Boxer Dogs in Norway. A Retrospective Study

This paper is a retrospective morphologic study of 7 young Boxer dogs, showing end-stage kidney lesions compatible with chronic pyelonephritis with severe segmental cortical atrophy and fibrosis, associated with chronic tubulointerstitial inflammation of varying degree. Azotemia was observed in 6 of the 7 cases. The gross kidney lesions were as follows: bilateral small kidneys with numerous segmental cortical scars causing depression of the renal cortical surface. Histologic examination revealed salient atrophy of nephrons, including paucity of glomeruli, glomerulocystic lesions, colloid-filled tubular microcysts, and a conspicuously increased occurrence of arteries with narrowed lumina caused by intimal thickening. These segmental abnormalities were accompanied by pronounced interstitial fibrosis. All but 1 dog showed salient tubulointerstitial lympho-plasmacytic infiltration, which in 3 cases also included diffuse infiltration of polymorphonuclear neutrophilic leukocyte (PMN)-cells and occurrence of tubular PMN-casts. Morphologic signs of abnormal metanephric differentiation (renal dysplasia) were observed in all cases in the form of atypical tubules or asynchronous nephronic development (immature glomeruli) or both. However, other morphologic primary dysplastic features were absent. Based on the morphologic features, it is concluded that the end-stage kidney disease in these young Boxer dogs was the result of chronic atrophic nonobstructive pyelonephritis, most probably caused by vesico-ureteral reflux, compatible with reflux nephropathy causing segmental hypoplasia (Ask-Upmark kidney) in man. It is proposed that atypical tubular epithelium in the form of adenomatoid proliferation of collecting duct epithelial cells should be considered an acquired compensatory lesion, rather than the result of disorganized metanephric development.

Dynamics in chimerism of T cells and dendritic cells in relapsed CML patients and the influence on the induction of alloreactivity following donor lymphocyte infusion

Donor lymphocyte infusion (DLI) after allogeneic SCT induces complete remissions in approximately 80% of patients with relapsed CML in chronic phase, but some patients do not respond to DLI. We studied absolute numbers of dendritic cell (DC) subsets and chimerism in T cells and two subsets of blood DCs (myeloid DCs (MDCs) and plasmacytoid DCs (PDCs)) in relation to DLI-induced alloreactivity. Based on T cell and DC chimerism, we identified three groups. Four patients were completely donor chimeric in T cells and DC subsets. These patients had an early stage of relapse, and three of the four patients attained complete molecular remission (CMolR) without significant GVHD. Six patients were completely donor in T cells and mixed chimeric in DC subsets. All patients entered CMolR, but this was associated with GVHD in four and cytopenia in three patients. Five patients had mixed chimerism in T cells and complete recipient chimerism in MDC; only two patients entered CMolR. Our data suggest that the combination of donor T cells and mixed chimerism in DC subsets induces a potent graft-versus-leukemia (GVL) effect in association with GVHD. DLI in patients with an early relapse and donor chimerism in both T cells and DC subsets results in GVL reactivity without GVHD.

Ubiquitylation in normal and malignant hematopoiesis: novel therapeutic targets

The modification of proteins with ubiquitin is involved in the regulation of various important biological pathways. A crucial step in this process is the modification of specific substrate proteins with ubiquitin by E3 ligases. The ubiquitylation of proteins can result in altered protein function or degradation by the 26S proteasome. Various proteins playing an important role during hematopoiesis are regulated via ubiquitin modification. Recently, alterations in ubiquitylation and proteasomal degradation have been implicated in hematological cancers. Based on these findings, novel therapies that specifically target ubiquitylation or the proteasome are currently being developed. In this review, we will highlight the role of ubiquitylation in normal and malignant hematopoiesis and discuss novel therapeutical approaches that are now tested in various hematological malignancies.

Monitoring gastric lymphoma in peripheral blood by quantitative IgH allele-specific oligonucleotide real-time PCR and API2-MALT1 PCR

Gastric extranodal marginal zone lymphoma (EMZL) often shows prolonged localised disease, but the present study demonstrated the presence of tumour cells in peripheral blood (PB) of low stage patients. We studied the presence of tumour cells in PB in gastric lymphoma patients harbouring or lacking t(11;18)(q21;q21), by real-time immunoglobulin (Ig)H allele-specific oligonucleotide-polymerase chain reaction (ASO-PCR) and API2-MALT1 PCR. Tumour cells were exclusively detected in PB of t(11;18)(q21;q21)+-EMZL patients. The presence of tumour cells in PB and gastric biopsy follow-up samples showed a good correlation in these patients, suggesting clinical relevance for monitoring of tumour cells in PB of gastric t(11;18)(q21;q21)+-EMZL patients.

ID1 and ID2 are retinoic acid responsive genes and induce a G0/G1 accumulation in acute promyelocytic leukemia cells

Acute promyelocytic leukemia (APL) is uniquely sensitive to treatment with all-trans retinoic acid (ATRA), which results in the expression of genes that induce the terminal granulocytic differentiation of the leukemic blasts. Here we report the identification of two ATRA responsive genes in APL cells, ID1 and ID2. These proteins act as antagonists of basic helix-loop-helix (bHLH) transcription factors. ATRA induced a rapid increase in ID1 and ID2, both in the APL cell line NB4 as well as in primary patient cells. In addition, a strong downregulation of E2A was observed. E2A acts as a general heterodimerization partner for many bHLH proteins that are involved in differentiation control in various tissues. The simultaneous upregulation of ID1 and ID2, and the downregulation of E2A suggest a role for bHLH proteins in the induction of differentiation of APL cells following ATRA treatment. To test the relevance of this upregulation, ID1 and ID2 were overexpressed in NB4 cells. Overexpression inhibited proliferation and induced a G0/G1 accumulation. These results indicate that ID1 and ID2 are important retinoic acid responsive genes in APL, and suggest that the inhibition of specific bHLH transcription factor complexes may play a role in the therapeutic effect of ATRA in APL.

Inhibitor of apoptosis proteins: new therapeutic targets in hematological cancer?

Apoptosis is an essential process for the selection and survival of lymphocytes. Resistance to apoptosis can promote malignant transformation of hematopoietic cells. Proteins that regulate apoptosis may therefore be critically involved in the development of hematological cancer. A delicate balance between pro- and antiapoptotic mechanisms determines whether a cell death signal can activate the execution of the apoptotic cell death program. The family of inhibitor of apoptosis (IAP) proteins is a recently identified, novel category of apoptosis-regulatory proteins. IAPs can inhibit the activation of caspases that are the executioners of apoptosis, activated by both the extrinsic and intrinsic pathway. IAPs may thereby set the threshold for apoptosis-activation and play a key role in the regulation of apoptotic cell death. IAPs themselves are also subject to strict regulation through feedback mechanisms. This paper focuses on the role of IAP family proteins in the regulation of apoptosis and discusses implications for their involvement in cancer and possible use for cancer therapy, especially in leukemias and lymphomas.

Identification of a novel CBFB-MYH11 transcript: implications for RT-PCR diagnosis

INTRODUCTION

The chromosome rearrangements inv(16)(p13q22) or t(16;16)(p13;q22) are present in approximately 10% of all cases with de novo acute myeloid leukemia and define a subgroup with a favorable prognosis. Both aberrations result in a CBFB-MYH11 fusion gene that can be detected by RT-PCR.

PATIENTS AND METHODS

To date, a total of 10 different in-frame CBFB-MYH11 fusion transcripts have been identified. A newly described transcript can not be amplified with the commonly used PCR primers since the MYH11 junction is located outside the amplified region (MYH11 cDNA position 2134).

RESULTS

We describe here a robust two-step RT-PCR assay that reliably detects all known CBFB-MYH11 transcripts types, including the new variant.

CONCLUSION

Because all previously established RT-PCR protocols may miss the new CBFB-MYH11 transcript, we propose to use the improved RT-PCR approach described here for the reliable detection of all known CBFB-MYH11 fusion transcripts.

Acquired skewing of Lyonization remains stable for a prolonged period in healthy blood donors

The pattern of X-chromosome inactivation (XCIP), or Lyonization, can be used to distinguish monoclonal from polyclonal cell populations in females. However, a skewed XCIP exists in hematopoietic cells in approximately 40% of healthy elderly females, interfering with interpretation of clonality assays. In hematopoiesis, an active stem cell pool is assumed to be present within a larger population of inactive stem cells, with a continuous exchange of cells between the two compartments. The assumption that the active stem cell pool size decreases with age may explain the phenomenon of acquired skewing occurring by chance and predicts the XCIP of this population to fluctuate. This fluctuation should be reflected in the XCIP of peripheral granulocytes. We examined the XCIP for fluctuations in time in peripheral granulocytes, monocytes and T cells of young, middle-aged and elderly healthy females. We used an optimized HUMARA PCR assay that eliminates unbalanced DNA amplification. We found no fluctuations in XCIP in any age group in up to 18 months follow-up. We conclude that acquired skewing arises gradually in life without fluctuations in XCIP and that analysis at multiple time points cannot distinguish monoclonal hematopoiesis from normal, skewed hematopoiesis.

Degradable dU-based DNA template as a standard in real-time PCR quantitation

Development of real-time quantitative PCR assays requires suitable positive controls. For assays with clinical applications, these controls may be difficult to obtain because some molecular aberrations are rare and patient material may be available in limited amounts. Because of the risk of introducing contaminations in the laboratory, cloned DNA is not a desirable alternative. We describe the use of dU-containing DNA as a positive control template in real-time quantitative PCR. dU-DNA constructs can be decontaminated by adding uracil N-glycosylase (UNG) to the reaction mixture. In addition, dU-DNA can be used for accurate quantification, because it allows quantification to be expressed in numbers of molecules. Since synthetic dU-DNA constructs can easily be quantitated spectroscopically, they provide a more accurate control than arbitrary cell line units. We applied this method for the detection of the E2A-Pbx1 gene fusion and show that UNG-containing reactions can be employed for diagnostics without loss of sensitivity, and that for positive and quantitative controls UNG negative reactions can be used. The use of dU-DNA provides a novel type of control template that can easily be integrated into existing PCR protocols.

Acute promyelocytic leukemia with a PLZF-RARalpha fusion protein

In most cases of acute promyelocytic leukemia (APL), a fusion of the promyelocytic leukemia (PML) and the retinoic acid receptor-alpha (RARalpha) genes occurs, resulting in the expression of a PML-RARalpha chimeric protein. In approximately 1% of the cases of APL, variant chromosomal aberrations may be found fusing RARa with other genes. Four variant mutations have been described, and the t(11;17)(q21;q23) translocation generating a promyelocyte leukemia zinc finger (PLZF)-RARalpha fusion gene is the most common. PLZF-RARalpha-positive APL forms a clinically distinct group because unlike PML-RARalpha-positive leukemia, it does not respond to retinoic acid with terminal granulocytic differentiation of the cells, and remissions cannot be achieved with retinoids alone. At the molecular level, this has been explained by the retinoic acid-insensitive binding of corepressor proteins to the PLZF part of the fusion protein, leading to sustained repression of target genes that are important for cellular differentiation. Targeting of the PLZF-RARalpha-bound corepressor complexes using a combination of all-trans retinoic acid (ATRA) and deacetylase inhibitors has shown that the repression of target genes can be relieved, allowing differentiation of the cells. In addition, when a combination of retinoic acid and the hematopoietic growth factor granulocyte colony-stimulating factor (G-CSF) is applied, the cells may be forced to undergo terminal differentiation, both in vitro and in vivo. This suggests that signals from the activated G-CSF receptor may induce the release of corepressor proteins from PLZF. Together, these findings indicate that PLZF-RARalpha-positive leukemia is not completely resistant to differentiation induction if the proper costimuli are given.

Molecular remission of Philadelphia/bcr-abl-positive acute myeloid leukaemia after treatment with anti-CD33 calicheamicin conjugate (gemtuzumab ozogamicin, CMA-676)

The anti-CD33 monoclonal antibody linked to NAc-gamma calicheamicin gemtuzumab ozogamicin (CMA-676) was used to treat a patient with Philadelphia/bcr-abl-positive acute myeloid leukaemia. We report a morphological and cytogenetic complete remission after treatment with two doses of gemtuzumab ozogamicin as a single agent. Using real-time polymerase chain reaction (PCR), gemtuzumab ozogamicin treatment resulted in a 3-log tumour mass reduction in bone marrow.

Retinoic acid receptor fusion proteins: friend or foe

Acute promyelocytic leukemia (APL) is characterized by a block in differentiation of hematopoietic cells at the promyelocytic stage of development. This disease is uniquely sensitive to treatment with pharmacological doses of all-trans retinoic acid (ATRA), and the combination of ATRA with chemotherapy has improved the durable disease-free survival in these patients to up to 80%. APL is characterized by chromosomal translocations that lead to the fusion of the retinoic acid receptor-alpha (RARalpha) to various partner genes. RARalpha functions as a ligand-inducible transcription factor and the aberrant RARalpha fusion proteins contribute to leukemic transformation by dominant inhibition of the expression of target genes that are important for cellular differentiation. This may at least in part be explained by an abnormally strong interaction with corepressor proteins leading to deacetylation of DNA and silencing of target genes. Most RARalpha fusion proteins can still be induced to transactivate genes, but only at very high doses of ligand, explaining why pharmacological doses of ATRA are necessary to obtain a therapeutic effect in these patients.

Dexamethasone does not counteract the response of acute promyelocytic leukaemia cells to all-trans retinoic acid

Retinoic acid syndrome is a serious condition that may complicate the treatment of acute promyelocytic leukaemia patients. This syndrome may be treated effectively with high-dose corticosteroid therapy and, as a result, many patients with acute promyelocytic leukaemia receive dexamethasone at some point during treatment. We investigated whether dexamethasone would also antagonize the beneficial effects of retinoic acid. In t(15;17)-positive NB4 cells, dexamethasone did not affect the retinoic acid induced differentiation, normalization of PML-nuclear bodies or the induction of thrombomodulin mRNA. Finally, dexamethasone did not inhibit the anti-proliferative effect of retinoic acid but rather showed anti-proliferative activity itself.

Complete remission of t(11;17) positive acute promyelocytic leukemia induced by all-trans retinoic acid and granulocyte colony-stimulating factor

The combined use of retinoic acid and chemotherapy has led to an important improvement of cure rates in acute promyelocytic leukemia. Retinoic acid forces terminal maturation of the malignant cells and this application represents the first generally accepted differentiation-based therapy in leukemia. Unfortunately, similar approaches have failed in other types of hematological malignancies suggesting that the applicability is limited to this specific subgroup of patients. This has been endorsed by the notorious lack of response in acute promyelocytic leukemia bearing the variant t(11;17) translocation. Based on the reported synergistic effects of retinoic acid and the hematopoietic growth factor granulocyte colony-stimulating factor (G-CSF), we studied maturation of t(11;17) positive leukemia cells using several combinations of retinoic acid and growth factors. In cultures with retinoic acid or G-CSF the leukemic cells did not differentiate into mature granulocytes, but striking granulocytic differentiation occurred with the combination of both agents. At relapse, the patient was treated with retinoic acid and G-CSF before reinduction chemotherapy. With retinoic acid and G-CSF treatment alone, complete granulocytic maturation of the leukemic cells occurred in vivo, followed by a complete cytogenetical and hematological remission. Bone marrow and blood became negative in fluorescense in situ hybridization analysis and semi-quantitative polymerase chain reaction showed a profound reduction of promyelocytic leukemia zinc finger-retinoic acid receptor-alpha fusion transcripts. This shows that t(11;17) positive leukemia cells are not intrinsically resistant to retinoic acid, provided that the proper costimulus is administered. These observations may encourage the investigation of combinations of all-trans retinoic acid and hematopoietic growth factors in other types of leukemia.

TRIADs: a new class of proteins with a novel cysteine-rich signature

Triad1 was recently identified as a nuclear RING finger protein, which is up-regulated during retinoic acid induced granulocytic differentiation of acute leukemia cells. Here we show that a cysteine-rich domain (C6HC), present in Triad1, is conserved in at least 24 proteins encoded by various eukaryotes. The C6HC consensus pattern C-x(4)-C-x(14-30)-C-x(1-4)-C-x(4)-C-x(2)-C-x(4)-H-x(4)-C defines this structure as the fourth family member of the zinc-binding RING, LIM, and LAP/PHD fingers. Strikingly, in 22 of 24 proteins the C6HC domain is flanked by two RING finger structures. We have termed the novel C6HC motif DRIL (double RING finger linked). The strong conservation of the larger tripartite TRIAD (two RING fingers and DRIL) structure indicates that the three subdomains are functionally linked and identifies a novel class of proteins.

In situ complement activation in porcine membranoproliferative glomerulonephritis type II

Pigs genetically deficient in complement factor H all develop lethal membranoproliferative glomerulonephritis (MPGN) type II characterized by massive glomerular deposits of complement, intramembranous dense deposits, and mesangial hypercellularity. To elucidate the chronological relationship between these glomerular changes, and to precisely determine the localization of glomerular complement deposits, we studied kidney specimens from factor H-deficient piglets at different ages from fetal life until terminal kidney failure had developed. Deposits of C3 and the terminal complement complex localized within the glomerular basement membrane (GBM) were present already in factor H-deficient fetuses, without concurrent intramembranous dense deposits or mesangial hypercellularity. Incipient subendothelial dense deposits containing complement appeared no earlier than four days after birth, and intramembranous dense deposits in older piglets with established MPGN type II also contained large amounts of complement as detected by immune electron microscopy. Onset of kidney failure coincided with pronounced mesangial hypercellularity and expansion, compromising glomerular capillary patency. Formation of glomerular capillary wall double contours coincided with electron microscopic evidence of laminar disintegration of intramembranous dense deposits. Complement was also deposited in the mesangial matrix, but not on glomerular cells. We conclude that all components of the alternative and terminal pathways of complement have access into the GBM and the mesangial matrix. In the absence of factor H, complement is spontaneously activated and deposited in situ in these locations resulting in dense deposit formation. It is proposed that factor H dysfunction may play an essential role even in human MPGN type II.

The judgement of facial expressions by depressed patients, their partners and controls

BACKGROUND

Research has shown that cognitive and interpersonal processes play significant roles in depression development and maintenance. Depressed patients judgments of emotions displayed in facial expressions, as well as those of their partners, allow for better understanding of these processes.

METHODS

In this study, twenty major depression outpatients, their partners and control persons (matched on the sex and age of the partner) judged facial expressions as to the emotions they felt were portrayed, at the patients outpatient admission. It was expected that the patients would judge the facial expression more negatively and less positively than their partners and that the partners would judge more negatively and less positively than the controls.

RESULTS

It was found that while both the patients and partners judged less positive emotions than the controls, the patients and partners did not judge the expressions differently. A trend in the same direction was found between the three groups as to judgment of negative emotions.

CONCLUSION

These findings are related back to interpersonal and cognitive theories of depression.

LIMITATION

A limitation of this study was the somewhat small patient population available for study.

CLINICAL RELEVANCE

This study helps to shed light on the similarity between interpersonal and cognitive processes of depressed patients and their partners.

Acute leukemias with structurally altered core binding factor subunits (t(8;21), inv(16), t(12;21)), 27-28 June 1997, Rotterdam, The Netherlands

In the summer of 1997, the first meeting on 'Acute Leukemias with Structurally Altered Core Binding Factor Subunits' was held. During the meeting, which attracted more than 140 participants, many recognized experts in the field of CBF and leukemia were present. In this short report we summarize new data on CBF involvement in leukemia and other diseases that were presented during the meeting.

Effects of diets with graded levels of naturally deoxynivalenol-contaminated oats on immune response in growing pigs

A trial was conducted to evaluate the effect of including different levels of deoxynivalenol (DON)-contaminated oats in the complete diets of growing pigs on immune response and performance. The diets contained 0.6, 1.8 and 4.7 mg DON/kg, and both restricted and ad libitum feeding were used. Performance was recorded as weight gain, feed intake, efficiency of feed utilization and carcass quality. Immune response parameters recorded included primary and secondary antibody titres after injections of five different antigens: Human serum albumin (HSA), sheep red blood cells (SRBC), paratuberculosis vaccine (MPT), tetanus toxoid (TT) and diphteria toxoid (DT). A johnin test was also performed. Lymphocyte stimulation response was measured with three different mitogens (PWM, ConA and PHA). A significant, DON dose-dependent reduction in secondary antibody response to tetanus toxoid was observed. A slightly higher mitogen response after PHA stimulation in lymphocytes from the medium and high DON groups compared to the low DON group after 9 weeks was considered inconclusive. No other indication of dose-dependent immune response inhibition or stimulation was found. Significantly reduced feed intake with increased levels of DON was observed in groups fed restricted rations according to weight, but not in animals fed ad libitum.

Non-verbal behavioral interactions of depressed patients with partners and strangers: the role of behavioral social support and involvement in depression persistence

Excessive support seeking and lack of receiving social support have been associated with depression onset and unfavorable course of depression. It has been assumed that social support is effected by observable behaviors that express involvement. Twenty-five patients with major depression were studied during a social interaction with their partner and a similar interaction, with a stranger, matched on the sex and age of the partner. We anticipated that (1) partners would display less involvement behaviors to the depressed patients than would strangers and that (2) lack of involvement would predict an unfavorable course of depression, as assessed for depression remission within 6 months of admission. The social interactions, conducted at admission, were videotaped and the behaviors were assessed by ethological methods. The frequency and duration of behavioral elements were associated on the basis of statistical criteria into behavioral factors. Certain factors were supposed to express (lack of) involvement during an interaction. In the patient-partner interaction it was found that both participants displayed lower levels of involvement as compared to the patient-stranger interaction. The patients' low involvement was reflected by less Speech, less Eagerness (yes-nodding and no-shaking), less Speaking Effort (head movements, looking and gesturing during speech) and more Active Listening (intense touching of one's own body and head movements during listening). The partners' low involvement was also expressed by less Speech and more Active Listening, together with less Encouragement (yes-nodding and 'um-hum'-ing during listening). In addition, the partners displayed less Speech to patients who did not remit within 6 months, whereas patients and strangers behaviors were not related to depression remission. These findings supported our anticipations and the findings are related back to data on social support, involvement and to previous human ethological studies on depression.

Depression relapse and ethological measures

Within the framework of interactional theories on depression, the question is raised whether depression relapse can be predicted by observable behavior of remitted patients and their interviewer during an interaction (i.e. discharge interview). Thirty-four patients were interviewed at hospital discharge and at a follow-up, 6 months later. Eight patients (23.5%) had relapsed at follow-up. Various behaviors of patients and interviewers were observed during an interview by ethological methods. One of the six patient behavioral factors, and none of the seven interviewer factors were related to relapse. Depression relapse patients displayed significantly less Active Listening (intense body touching and head movements during listening) during the interview at hospital discharge than those with stable remission. Results on Active Listening could not be explained by the degree of retardation (HRSD) and underlined the significance of interpersonal mechanisms in the onset and maintenance of depression.

Eradication of porcine factor H deficiency in Norway

In pigs a hereditary deficiency of the complement-inhibitory protein factor H consistently leads to the development of lethal membranoproliferative glomerulonephritis type II. This autosomal recessive disease has been a common cause of early losses of piglets in the Norwegian Yorkshire breed, but has not been reported in the Norwegian Landrace breed. The aim of the present work was to identify carriers of factor H deficiency and to eradicate the disease from commercial pig populations. Factor H in plasma was measured by an enzyme immunoassay. Sixteen known carriers of the disease (parents of factor H-deficient offspring) had half the level of factor H (median 110, range 87 to 156 mg/litre) recorded in 17 homozygous healthy Yorkshire pigs (median 212, range 183 to 293 mg/litre) and 20 Landrace pigs (median 227, range 200 to 255 mg/litre). Factor H analysis in 397 piglets produced by the mating of known carriers revealed an approximately 1:2:1 distribution of individuals with very low, half-normal and normal levels of factor H representing homozygous deficient, heterozygous and homozygous healthy individuals. Thus, carriers could be identified reliably by measuring the plasma concentration of factor H. Most of the population of Norwegian Yorkshire breeding pigs (490 pigs) was therefore examined, and a half-normal factor H level consistent with the carrier state was found in 13.5 per cent. These animals were prevented from breeding and since then no losses of piglets suspected of being due to factor H deficiency have been reported. No carrier was identified among 102 Norwegian Landrace boars, almost excluding the existence of factor H deficiency in this breed.

Accessory ossification centres associated with osteochondral fragments in the extremities of horses

Fifty-six tarsocrural joints and 94 metatarsophalangeal joints were examined, at necropsy, from horses aged < or = 2 years. Osteochondral fragments at the cranial aspect of the intermediate ridge of the distal part of the tibia were seen in six horses, and at the proximoplantar aspect of the proximal phalanx in seven horses. Defects in the proximoplantar aspect of the proximal phalanx without osteochondral fragments were seen in a further two horses. Inflammatory and degenerative changes were not observed in any of the joints examined. From the incidence and natural course of these fragments, and from the radiological and microscopical findings, accessory ossification centres would seem the most probable cause of the osteochondral fragments at the cranial aspect of the intermediate ridge of the distal part of the tibia and at the proximoplantar aspect of the proximal phalanx.

Detection of partial cDNA sequences differentially expressed in patients with myelodysplasia

The most common chromosomal aberrations in myelodysplastic syndromes (MDS) are complete or partial loss of chromosomes 5 and 7, and trisomy 8. To identify genes important in the pathogenesis of this disease that could be associated with these gross chromosomal defects, we have employed the differential display PCR (DDPCR) procedure developed by Liang and Pardee. This method allows simultaneous comparison of several cDNA sources for the presence of differentially expressed genes. Polymorphonuclear cells (PMNs) from two MDS patients, containing a 5q deletion or a trisomy 8, and three healthy controls were used. Initial screening resulted in the identification of five and three partial cDNA sequences, respectively that were either differentially expressed in both patient samples or in individual patients, as compared with the controls. The authenticity of aberrant expression was verified by reanalyzing the same primer combinations on newly prepared cDNA. Differential expression of the three remaining fragments was subsequently checked on a larger panel of MDS patients, using amplicon-specific primer sets. These were obtained by cloning and sequencing of the fragments. For one partial cDNA (DC3), the original expression pattern, i.e., decreased expression in individual MDS patients, was confirmed. These results demonstrate the utility of the DDPCR procedure to isolate differentially expressed sequences in primary patient samples where the availability of cells is a limiting factor.

Porcine membranoproliferative glomerulonephritis type II: an autosomal recessive deficiency of factor H

Hypocomplementaemic hereditary membranoproliferative glomerulonephritis (MPGN) type II is a common cause of the early loss of piglets in the Norwegian Yorkshire breed. The disease is associated with extensive complement activation due to a deficiency of factor H, a plasma protein which regulates complement. To investigate its mode of inheritance, 33 litters were bred from healthy animals associated with the disease, and a total of 385 recorded offspring were produced. The examination of renal tissue from the hypocomplementaemic piglets consistently revealed diagnostic signs of MPGN type II, including thickening of the glomerular capillary wall and proliferation of mesangial cells, dense intramembranous deposits, and massive glomerular deposits of complement component C3 and the terminal complement complex. No such glomerular lesions were detected in 20 normocomplementaemic littermates. The 88 affected piglets were present in 27 litters containing a total of 317 piglets, and there were approximately equal numbers of each sex. Retrospective immunoblot analysis and enzyme immunoassay of plasma samples from the MPGN-affected piglets and their healthy littermates revealed that the affected piglets were deficient in factor H, whereas the healthy piglets were not. It is concluded that porcine factor H deficiency is inherited as a simple autosomal recessive trait with complete penetrance, and consistently results in hypocomplementaemia and lethal membranoproliferative glomerulonephritis type II.

Multimeric complexes of the PML-retinoic acid receptor alpha fusion protein in acute promyelocytic leukemia cells and interference with retinoid and peroxisome-proliferator signaling pathways

The t(15;17) chromosomal translocation, specific for acute promyelocytic leukemia (APL), fuses the PML gene to the retinoic acid receptor alpha (RAR alpha) gene, resulting in expression of a PML-RAR alpha hybrid protein. In this report, we analyzed the nature of PML-RAR alpha-containing complexes in nuclear protein extracts of t(15;17)-positive cells. We show that endogenous PML-RAR alpha can bind to DNA as a homodimer, in contrast to RAR alpha that requires the retinoid X receptor (RXR) dimerization partner. In addition, these cells contain oligomeric complexes of PML-RAR alpha and endogenous RXR. Treatment with retinoic acid results in a decrease of PML-RAR alpha protein levels and, as a consequence, of DNA binding by the different complexes. Using responsive elements from various hormone signaling pathways, we show that PML-RAR alpha homodimers have altered DNA-binding characteristics when compared to RAR alpha-RXR alpha heterodimers. In transfected Drosophila SL-3 cells that are devoid of endogenous retinoid receptors PML-RAR alpha inhibits transactivation by RAR alpha-RXR alpha heterodimers in a dominant fashion. In addition, we show that both normal retinoid receptors and the PML-RAR alpha hybrid bind and activate the peroxisome proliferator-activated receptor responsive element from the Acyl-CoA oxidase gene, indicating that retinoids and peroxisome proliferator receptors may share common target genes. These properties of PML-RAR alpha may contribute to the transformed phenotype of APL cells.

Light therapy for seasonal affective disorder. The effects of timing

BACKGROUND

Sixty-eight patients with seasonal affective disorder participated in a 10,000-lux light treatment study in which two questions were addressed: do response rates differ when the light is applied at different times of the day and does short-term rank ordering of morning and evening light influence response rates?

METHOD

Three groups of patients received a 4-day light treatment: (I) in the morning (8.00-8.30 a.m., n = 14), (II) in the afternoon (1.00-1.30 p.m., n = 15) or (III) in the evening (8.00-8.30 p.m., n = 12). Two additional groups of patients received two days of morning light treatment followed by two days of evening light (IV, n = 13) or vice versa (V, n = 14).

RESULTS

Response rates for groups I, II and III were 69, 57 and 80% respectively, with no significant differences between them. Response rates for groups IV and V were 67 and 50% respectively; this difference was not significant and these percentages did not differ significantly from those of groups I and III.

CONCLUSIONS

The results indicate that the timing of light treatment is not critical and that short-term rank ordering of morning and evening light does not influence therapeutic outcome.

Performance of four different rat strains in the autoshaping, two-object discrimination, and swim maze tests of learning and memory

The performance of four strains of rats commonly used in behavioural research was assessed in three different tests of learning and memory. The four strains included three outbred lines (Long-Evans, Sprague-Dawley, Wistar) and one inbred strain (S3). Learning and memory were tested using three different paradigms: autoshaping of a lever press, a two-object discrimination test, and performance in a two-island swim maze task. The pigmented strains showed better performance in the autoshaping procedure: the majority of the Long-Evans and the S3 rats acquired the response, and the majority of the Wistar and Sprague-Dawley failed to acquire the response in the set time. The albino strains were slightly better in the swim maze than the pigmented strains. There appeared to be a speed/accuracy trade-off in the strategy used to solve the task. This was also evident following treatment with the cholinergic-depleting agent hemicholinium-3. The performance of the Long-Evans rats was most affected by the treatment in terms of accuracy and the Wistar and Sprague-Dawleys in terms of speed. In the two-object discrimination test only the Long-Evans showed satisfactory performance and were able to discriminate a novel from a known object a short interval after initial exposure. These results show large task- and strain-dependent differences in performance in tests of learning and memory. Some of the performance variation may be due to emotional differences between the strains and may be alleviated by extra training. However, the response to pharmacological manipulation may require more careful evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)

Hereditary porcine membranoproliferative glomerulonephritis type II is caused by factor H deficiency

We have recently described hereditary membranoproliferative glomerulonephritis type II in the pig. All affected animals had excessive complement activation, revealed as low plasma C3, elevated plasma terminal complement complex, and massive deposits of complement in the renal glomeruli, and eventually died of renal failure within 11 wk of birth. The aim of the present study was to investigate the cause of complement activation in this disease. Transfusion of normal porcine plasma to affected piglets inhibited complement activation and increased survival. Plasma was successively fractionated and the complement inhibitory effect of each fraction tested in vivo. A single chain 150-kD protein which showed the same complement inhibitory effect as whole plasma was finally isolated. Immunologic cross-reactivity, functional properties, and NH2-terminal sequence identified the protein as factor H. By Western blotting and enzyme immunoassay, membranoproliferative glomerulonephritis-affected piglets were demonstrated to be subtotally deficient in factor H. At 1 wk of age, median (range) factor H concentration was 1.6 mg/liter (1.1-2.3) in deficient animals (n = 13) and 51 mg/liter (26-98) in healthy littermates (n = 52). Our data show that hereditary porcine membrano-proliferative glomerulonephritis type II is caused by factor H deficiency.