Nuclear poly(ADP-ribose) activity is a therapeutic target in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating and fatal motor neuron disease. Diagnosis typically occurs in the fifth decade of life and the disease progresses rapidly leading to death within ~ 2–5 years of symptomatic onset. There is no cure, and the few available treatments offer only a modest extension in patient survival. A protein central to ALS is the nuclear RNA/DNA-binding protein, TDP-43. In > 95% of ALS patients, TDP-43 is cleared from the nucleus and forms phosphorylated protein aggregates in the cytoplasm of affected neurons and glia. We recently defined that poly(ADP-ribose) (PAR) activity regulates TDP-43-associated toxicity. PAR is a posttranslational modification that is attached to target proteins by PAR polymerases (PARPs). PARP-1 and PARP-2 are the major enzymes that are active in the nucleus. Here, we uncovered that the motor neurons of the ALS spinal cord were associated with elevated nuclear PAR, suggesting elevated PARP activity. Veliparib, a small-molecule inhibitor of nuclear PARP-1/2, mitigated the formation of cytoplasmic TDP-43 aggregates in mammalian cells. In primary spinal-cord cultures from rat, Veliparib also inhibited TDP-43-associated neuronal death. These studies uncover that PAR activity is misregulated in the ALS spinal cord, and a small-molecular inhibitor of PARP-1/2 activity may have therapeutic potential in the treatment of ALS and related disorders associated with abnormal TDP-43 homeostasis.

Progression of alpha-synuclein pathology in multiple system atrophy of the cerebellar type

AIMS

The aim of this study was to identify early foci of α-synuclein (α-syn pathology) accumulation, subsequent progression and neurodegeneration in multiple system atrophy of the cerebellar type (MSA-C).

METHODS

We analysed 70-μm-thick sections of 10 cases with MSA-C and 24 normal controls.

RESULTS

MSA-C cases with the lowest burden of pathology showed α-syn glial cytoplasmic inclusions (GCIs) in the cerebellum as well as in medullary and pontine cerebellar projections. Cerebellar pathology was highly selective and severely involved subcortical white matter, whereas deep white matter and granular layer were only mildly affected and the molecular layer was spared. Loss of Purkinje cells increased with disease duration and was associated with neuronal and axonal abnormalities. Neocortex, basal ganglia and spinal cord became consecutively involved with the increasing burden of α-syn pathology, followed by hippocampus, amygdala, and, finally, the visual cortex. GCIs were associated with myelinated axons, and the severity of GCIs correlated with demyelination.

CONCLUSIONS

Our findings indicate that cerebellar subcortical white matter and cerebellar brainstem projections are likely the earliest foci of α-syn pathology in MSA-C, followed by involvement of more widespread regions of the central nervous system and neurodegeneration with disease progression.

Risk factors and clinical outcomes of cytomegalovirus disease occurring more than one year post solid organ transplantation

BACKGROUND

Cytomegalovirus (CMV) disease typically occurs during the first year after solid organ transplantation, after cessation of antiviral prophylaxis. CMV occurring after the first year is uncommon and not well described.

METHODS

We conducted a case-control study to identify potential risk factors and a retrospective cohort study to evaluate 1-month mortality in solid organ transplant (SOT) recipients who developed CMV disease after the first year post transplant, or "very late CMV" (VLCMV), compared with those developing CMV within the first year (CMV Y1), adjusting for demographics, donor and recipient CMV serostatus, immunosuppression, rejection, and co-morbidities.

RESULTS

We identified 85 SOT recipients with CMV disease at a single transplant center between January 2006 and October 2008: 23 (27%) had VLCMV and 62 (73%) had CMV Y1. Heart transplantation was independently associated with increased risk (adjusted odd ratio [OR] 4.11; 95% confidence interval [CI] 1.34-12.61; P = 0.01) for VLCMV. Patients with VLCMV had increased 1-month mortality (unadjusted OR 5.39; 95% CI 1.06-27.48; P = 0.02). Mortality was uncommonly attributable to CMV.

CONCLUSIONS

CMV disease continues to occur after the first year post solid organ transplantation, particularly in heart transplant recipients, and can be associated with poor outcomes. CMV should be suspected in patients with symptoms or laboratory findings consistent with CMV, even if the patients present >1 year post transplant.

Evaluation of EGFR mutation status in cytology specimens: an institutional experience

Epidermal growth factor receptor (EGFR) mutation status has been shown to predict response to anti-EGFR tyrosine kinase inhibitors in non-small cell lung cancer (NSCLC). In patients with advanced-stage NSCLC, evaluation of mutational status is increasingly requested on biopsy or fine-needle aspiration specimens, which often have limited material. There are limited data on the suitability of cytology cell blocks (CB) for EGFR mutation testing. In this study, we report our institutional experience with cytology cell block material for EGFR mutation testing. We retrospectively reviewed EGFR mutation analyses performed on 234 surgical (SP) and cytology (CB) from October 2007 to May 2010. One hundred ninety-two SP specimens and 42 CB specimens were evaluated for EGFR mutation. CB specimens were evaluated for overall specimen size based on aggregate cellularity in comparison to small biopsy specimens, and percent tumor. Of the 192 SP and 42 CB specimens, 31 (16.1%) and 11 (26.2%) were positive for EGFR mutation, respectively; there does not appear to be an association between mutation detection rate and the source of the specimen (P = 0.124). Limited DNA was obtained from 70.0% (29/42), including 81.8% (9/11) of those which were mutation positive. Additionally, 45.4% (5/11) of mutation positive specimens had extremely low DNA yields. Although 16.6% (7/42) of CB specimens had <10% tumor, all 11 mutation positive CB cases had >10% tumor. These data indicate that CB specimens provide an alternative source for molecular evaluation of NSCLC, and that tumor percentage may be more important than specimen size and/or DNA yield in determining the suitability of these specimens for testing.

Establishment of a standardized multiplex assay with the analytical performance required for quantitative measurement of BCR-ABL1 on the international reporting scale

Accurate and standardized methods for the quantitative measurement of BCR–ABL1 are a prerequisite for monitoring of treatment response in t(9;22)-positive leukemia. Here, we describe a novel multiplex assay system based on the proven TaqMan and Armored RNA technologies and optimized for sensitive detection of three BCR–ABL1 fusion transcripts and ABL1 in a single reaction. Analytical experiments confirmed the absence of significant competition between the simultaneous amplification reactions and established the sensitivity, linearity and precision of the assay. Comparative studies with 115 clinical specimens resulted in high qualitative and quantitative agreement with independent singleplex laboratory-developed tests routinely used in clinical testing. Direct comparison with a reference laboratory calibrated to the international scale (IS) demonstrated minimal analytical bias between methods and an overall accuracy and precision within the performance range required for quantitative measurement of BCR–ABL1 on the IS. We conclude that detection of e1a2, b2a2, b3a2 and ABL1 can be achieved in a multiplex assay format compatible with IS reporting. Further clinical validation of the assay could improve the operational efficiency of clinical laboratories, increase their adherence to current recommendations for b2a2/b3a2 reporting on the IS and provide for the first time an opportunity to standardize e1a2-monitoring results.

Factors associated with survival probability in autopsy-proven frontotemporal lobar degeneration

OBJECTIVE

To examine the clinical and pathological factors associated with survival in autopsy-confirmed frontotemporal lobar degeneration (FTLD).

METHODS

The final analysis cohort included 71 patients with pathologically proven FTLD, excluding patients with clinical motor neuron disease (MND), evaluated at the University of Pennsylvania or at the University of California, San Francisco. We assessed clinical and demographic features; cognitive functioning at presentation; genetic markers of disease; and graded anatomical distribution of tau, ubiquitin and amyloid pathology.

RESULTS

The tau-negative group (n = 35) had a median survival time of 96 months (95% CI: 72-114 months), whereas the tau-positive group (n = 36) had a median survival time of 72 months (95% CI: 60-84 months). Patients with tau-positive pathology across all brain regions had shorter survival than those with tau-negative pathology in univariate Cox regression analyses (Hazard ratio of dying = 2.003, 95% CI = 1.209-3.318, p = 0.007).

CONCLUSIONS

Tau-positive pathology represents a significant risk to survival in FTLD, whereas tau-negative pathology is associated with a longer survival time when clinical MND is excluded.

Corticobasal syndrome and primary progressive aphasia as manifestations of LRRK2 gene mutations

BACKGROUND

Mutations in the LRRK2 gene are an important cause of familial and nonfamilial parkinsonism. Despite pleomorphic pathology, LRRK2 mutations are believed to manifest clinically as typical Parkinson disease (PD). However, most genetic screens have been limited to PD clinic populations.

OBJECTIVE

To clinically characterize LRRK2 mutations in cases recruited from a spectrum of neurodegenerative diseases.

METHODS

We screened for the common G2019S mutation and several additional previously reported LRRK2 mutations in 434 individuals. A total of 254 patients recruited from neurodegenerative disease clinics and 180 neurodegenerative disease autopsy cases from the University of Pennsylvania brain bank were evaluated.

RESULTS

Eight cases were found to harbor a LRRK2 mutation. Among patients with a mutation, two presented with cognitive deficits leading to clinical diagnoses of corticobasal syndrome and primary progressive aphasia.

CONCLUSION

The clinical presentation of LRRK2-associated neurodegenerative disease may be more heterogeneous than previously assumed.

Loss of brain tau defines novel sporadic and familial tauopathies with frontotemporal dementia

Dementia lacking distinctive histopathology (DLDH) or frontotemporal lobe degeneration (FTLD) is the most common neuropathological diagnosis for sporadic frontotemporal dementias (FTDs). The hallmarks of DLDH are neuron loss and gliosis in the absence of any disease-specific brain lesion. Similar brain pathology is also seen in a familial FTD pedigree known as hereditary dysphasic disinhibition dementia 2 (HDDD2). Abnormality in the function or isoform composition of the microtubule binding protein tau is a prominent feature in the brains of many patients with sporadic and hereditary FTDs. Therefore, we studied the tau protein in different brain regions from DLDH and HDDD2 patients. Our results indicate that a selective loss of all six tau isoforms, but not tau mRNA, occurs in these brains compared to normal control and Alzheimer's disease brains. Loss of tau protein was identified by Western blot analysis of protein extracts from DLDH and HDDD2 brains in regions both with and without neuronal degeneration. Functionally, this loss of tau protein may be equivalent to pathogenic mutations in the tau gene identified in familial FTD with parkinsonism linked to chromosome 17 (FTDP-17). Thus, DLDH and HDDD2 are novel tauopathies with a unique mechanism of pathogenesis. The presence of tau mRNA in these brains suggests that the level of tau protein may be controlled posttranscriptionally, at the level of either translation or mRNA stability.

Bone marrow engraftment analysis after allogeneic bone marrow transplantation

BME analysis of allo-BMT patients is used to confirm engraftment and detect MC after transplant. With frequent monitoring, the detection of MC by BME analysis may alert clinicians to a high risk of relapse and allow early intervention with a rapid taper of immunosuppression or DLI therapy. In pancytopenic patients BME analysis can help differentiate relapse from drug toxicity or infection. Although many methods have been used for BME analysis, PCR amplification of STR loci is the choice of many clinical laboratories because it is informative, quantitative, relatively rapid, and sensitive. The sensitivity of BME analysis is dependent upon many factors that need to be optimized by the laboratory performing the analysis. Although BME analysis is complex, the clinical significance for allo-BMT patients warrants the effort to develop, validate, and perform BME analysis in support of the allo-BMT service.

A novel, non-nested reverse-transcriptase polymerase chain reaction (RT-PCR) test for the detection of the t(15;17) translocation: a comparative study of RT-PCR cytogenetics, and fluorescence In situ hybridization

BACKGROUND

The development of a rapid and simple reverse-transcription polymerase chain reaction (RT-PCR) assay is described that identifies the promyelocytic leukemia- retinoic acid receptor alpha (PML-RARa) hybrid messenger RNA (mRNA), a characteristic feature of acute promyelocytic leukemia (APL).

METHODS AND RESULTS

Randomly primed complementary (cDNA) is synthesized from leukocyte RNA and amplified in the presence of Taq Gold in 2 separate reaction tubes containing primer pairs specific for intron 3 (bcr 3, long [L] form mRNA transcript) and intron 6 (bcr 1, short [S] form)/exon 6 (bcr 2, variant [V] form) breakpoints in PML, respectively. The different sized products generated from each RNA transcript (S, L, or V forms) are readily and unambiguously distinguishable after agarose gel electrophoresis without the need for either nested PCR or hybridization. The sensitivity of the assay is 1 in 10,000 to 1 in 100,000. The separate amplification of a b2-microglobulin transcript controls for adequate RNA and cDNA preparation. The newly developed assay was used clinically for the evaluation of 78 patients with APL. It was rapid and more sensitive than cytogenetic karyotyping, both for the diagnosis of APL and the assessment of minimal residual disease (MRD) after therapy. RT-PCR detected PML-RARa mRNA in all cases positive for the t(15;17) translocation by cytogenetics. However, as many as 50% and 80% of the diagnostic specimens and the specimens for MRD assessment, respectively, that were positive by RT-PCR were negative by cytogenetics. The ratio of cases with L-form to S-form PML-RARa fusion transcript was 2:1, whereas 3 cases (10%) had fusion sites in exon 6 of the PML gene (V forms). In addition, approximately 50% of the patients were diagnosed morphologically with microgranular M3V-type leukemia, but no significant correlation with PML breakpoints was found.

CONCLUSION

The current assay is rapid, sensitive, and specific without using nested PCR or hybridization.

Graft-versus-tumor induction with donor leukocyte infusions as primary therapy for patients with malignancies

PURPOSE

Histocompatible allogeneic donor leukocyte infusions (DLIs) were administered as primary cancer therapy in a phase I trial to determine (1) whether mixed chimerism could be detected without a prior allogeneic transplantation, (2) the toxicity of primary DLI, and (3) whether a graft-versus-tumor (GVT) reaction could be observed.

PATIENTS AND METHODS

Eighteen patients were studied. Patients received interferon alfa-2b for a minimum of 4 weeks, followed by DLI (level 1). Patients with no toxicity or engraftment were eligible to receive cytarabine or cyclophosphamide followed by another course of DLI (level 2). Engraftment was determined using polymerase chain reaction amplification of donor and host-specific DNA polymorphisms.

RESULTS

Donor cells were detected in the blood in 14 of 16 assessable patients within 1 hour of DLI. Chimerism detectable 4 weeks after DLI was observed in four patients, and five patients were not assessable. Prior autologous transplantation was associated with late chimerism (P =.0014). Acute graft-versus-host disease (GVHD) occurred in four of 16 assessable patients (grade 1, two patients; grade 2, one patient; grade 4, one patient). One patient with grade 4 acute GVHD developed pancytopenia. Only the four patients treated after prior autologous transplantation developed acute GVHD (P =.0005). Three of four patients with acute GVHD and late chimerism responded to primary DLI, and one patient was not assessable for response.

CONCLUSION

Allogeneic adoptive immunotherapy resulted in sustained chimerism, acute GVHD, and a GVT response in heavily pretreated patients. This indicates that it may be possible to generate a direct GVT response for patients with malignancies without the need for intensive conditioning therapy immediately before DLI. Immunosuppression may be required for sustained donor cell engraftment.

Thrombosis in a patient with combined homozygosity for the factor V Leiden mutation and a mutation in the 3'-untranslated region of the prothrombin gene

The factor V Leiden mutation and a guanine-to-adenine mutation at nucleotide 20210 in the 3'-untranslated region of the prothrombin gene are the most prevalent genetic defects in patients with deep venous thrombosis. Heterozygosity for the factor V Leiden and the prothrombin gene mutations is found in approximately 20 and 6% of unselected patients with deep venous thrombosis, respectively, whereas the prevalences of the two mutations in the general Caucasian population are approximately 6 and 2%, respectively. We evaluated an 18-year-old man presenting with a spontaneous episode of superficial venous thrombosis for the presence of an inherited thrombotic disorder. After excluding deficiencies of antithrombin, protein C, and protein S, genomic DNA from the patient was tested for the presence of the factor V Leiden and prothrombin gene mutations. Consanguinity was not present in the family. Genotyping demonstrated that the patient was homozygous for the factor V Leiden and prothrombin gene mutations. The likelihood of identifying an individual in the general population who is homozygous for both mutations similar to our patient is estimated to be less than 1 in 10 million.

Heparin facilitates dissociation of complexes between thrombin and a reactive site mutant (L444R) of heparin cofactor II

Heparin cofactor II (HCII) inhibits thrombin by forming a stable 1:1 complex. Heparin and dermatan sulfate increase the rate of complex formation >/=1000-fold. Mutation of leucine 444 to arginine at the P1 position of recombinant HCII (rHCII) increases the rate of inhibition of thrombin approximately 100-fold in the absence of a glycosaminoglycan (Derechin, V. M., Blinder, M. A., and Tollefsen, D. M. (1990) J. Biol. Chem. 265, 5623-5628). We now report that heparin facilitates dissociation of the thrombin-rHCII(L444R) complex. In the presence of heparin, thrombin is inhibited rapidly and completely by a 35-fold molar excess of rHCII(L444R), but subsequently approximately 50% of the thrombin activity reappears with a t1/2 of approximately 20 min. At higher ratios of rHCII(L444R) to thrombin, the reappearance of thrombin activity is delayed and the final plateau of activity is decreased. Electrophoretic analysis indicates that proteolysis of excess rHCII(L444R) precedes the reappearance of thrombin activity. Addition of heparin at longer intervals after formation of the thrombin-rHCII(L444R) complex causes a progressive decrease in the thrombin plateau, suggesting that in the absence of heparin the complex is slowly converted to a non-dissociable form. By contrast to heparin, dermatan sulfate does not facilitate dissociation of the thrombin-rHCII(L444R) complex. Our findings indicate that the P1 residue of HCII affects not only the rate of inhibition of thrombin but also the stability of the resulting complex.

Murine heparin cofactor II: purification, cDNA sequence, expression, and gene structure

Heparin cofactor II (HCII) is a glycoprotein in human plasma that inhibits thrombin rapidly in the presence of dermatan sulfate or heparin. Unexpectedly, we found that HCII activity in murine plasma is present in two proteins of 68 and 72 kDa. The two proteins have the same N-terminal amino acid sequence, and both react with an antibody raised against the C-terminal nine amino acid residues of murine HCII predicted from the cDNA sequence. Treatment of the two proteins with peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase yields a single 54-kDa band. Thus, murine plasma contains two forms of HCII that appear to have identical amino acid sequences but differ in the composition of their N-linked oligosaccharides. HCII cDNA clones isolated from a murine liver library include a 1434 bp open reading frame following the first Met codon, a TAA stop codon, and 580 bp of 3'-untranslated sequence terminating in a poly(A) tail. The amino acid sequence deduced from the cDNA contains the N-terminal sequence of purified murine plasma HCII preceded by a 23-residue hydrophobic sequence presumed to be the signal peptide. The amino acid sequence of murine HCII is 87% identical to that of human HCII, the greatest variability occurring in the N-terminal portion of the protein. Northern blot analysis reveals a 2.3-kb HCII mRNA in murine and human liver, but no HCII mRNA is detectable in heart, brain, spleen, lung, skeletal muscle, kidney, testis, placenta, pancreas, or intestine. Southern blot analysis of restriction fragment length polymorphisms in progeny on interspecific and intersubspecific crosses indicates that mice have a single HCII gene (designated Hcf2), which maps to chromosome 16 between Prm-1 and Igl. The murine HCII gene is approximately 7.1 kb in size and consists of at least four exons and three introns. The intron/exon organization is identical to that of the human HCII gene except at the 5' end, where the murine gene may lack a large intron in the 5'-untranslated region. Our results indicate that HCII is more highly conserved than the human and murine homologues of other serpins such as alpha 1-antitrypsin and alpha 1-antichymotrypsin.

The N-terminal acidic domain of heparin cofactor II mediates the inhibition of alpha-thrombin in the presence of glycosaminoglycans

Heparin cofactor II (HCII) is a glycoprotein in human plasma that inhibits thrombin and chymotrypsin. Inhibition occurs when the protease attacks the reactive site peptide bond in HCII (Leu444-Ser445) and becomes trapped as a covalent 1:1 complex. Dermatan sulfate and heparin increase the rate of inhibition of thrombin, but not of chymotrypsin, greater than 1000-fold. The N-terminal portion of HCII contains two acidic repeats (Glu56-Asp-Asp-Asp-Tyr-Leu-Asp and Glu69-Asp-Asp-Asp-Tyr-Ile-Asp) that may bind to anion-binding exosite I of thrombin to facilitate covalent complex formation. To examine the importance of the acidic domain, we have constructed a series of 5' deletions in the HCII cDNA and expressed the recombinant HCII (rHCII) in Escherichia coli. Apparent second-order rate constants (k2) for inhibition of alpha-thrombin and chymotrypsin by each variant were determined. Deletion of amino acid residues 1-74 had no effect on the rate of inhibition of alpha-thrombin or chymotrypsin in the absence of a glycosaminoglycan. Similarly, the rate of inhibition of alpha-thrombin in the presence of a glycosaminoglycan was unaffected by deletion of residues 1-52. However, deletion of residues 1-67 (first acidic repeat) or 1-74 (first and second acidic repeats) greatly decreased the rate of inhibition of alpha-thrombin in the presence of heparin, dermatan sulfate, or a dermatan sulfate hexasaccharide that comprises the minimum high-affinity binding site for HCII. Deletion of one or both of the acidic repeats increased the apparent affinity of rHCII for heparin-Sepharose, suggesting that the acidic domain may interact with the glycosaminoglycan-binding site of native rHCII. The stimulatory effect of glycosaminoglycans on native rHCII was decreased by a C-terminal hirudin peptide which binds to anion-binding exosite I of alpha-thrombin. Furthermore, the ability of native rHCII to inhibit gamma-thrombin, which lacks the binding site for hirudin, was stimulated weakly by glycosaminoglycans. These results support a model in which the stimulatory effect of glycosaminoglycans on the inhibition of alpha-thrombin is mediated, in part, by the N-terminal acidic domain of HCII.