Development of an ultraprecision metal mirror on additively manufactured Ti-6Al-4V.

Metal mirrors for precise optical applications are commonly fabricated by coating of a metal base substrate with a nickel-phosphorus alloy (NiP). The NiP layer is then processed by precision diamond turning and polishing to obtain a high-quality mirror surface. In this work, Ti-6Al-4V samples that were made by additive manufacturing, also called 3D printing, were used as a base for the development of metal mirrors. The additively manufactured samples were electroplated with a NiP coating and machined using single-point diamond turning (SPDT) to obtain a flat mirror with optical quality and low form error surface. The periodic structure of the SPDT toolmark was then removed by polishing postprocessing. Polishing optimization was first performed on NiP-coated aluminum test samples to find an optimal polishing setup. Based on this optimization, postprocessing of titanium samples was carried out by pitch polishing in combination with 1, 0.25, and 0.1µm diamond slurries. Using this polishing processing, a scratch-free surface was attained with surface microroughness below 0.5 nm.

A Cre-conditional MYCN-driven neuroblastoma mouse model as an improved tool for preclinical studies.

Neuroblastoma, a childhood cancer that originates from neural crest-derived cells, is the most common deadly solid tumor of infancy. Amplification of the MYCN oncogene, which occurs in approximately 20-25% of human neuroblastomas, is the most prominent genetic marker of high-stage disease. The availability of valid preclinical in vivo models is a prerequisite to develop novel targeted therapies. We here report on the generation of transgenic mice with Cre-conditional induction of MYCN in dopamine ß-hydroxylase-expressing cells, termed LSL-MYCN;Dbh-iCre. These mice develop neuroblastic tumors with an incidence of >75%, regardless of strain background. Molecular profiling of tumors revealed upregulation of the MYCN-dependent miR-17-92 cluster as well as expression of neuroblastoma marker genes, including tyrosine hydroxylase and the neural cell adhesion molecule 1. Gene set enrichment analyses demonstrated significant correlation with MYC-associated expression patterns. Array comparative genome hybridization showed that chromosomal aberrations in LSL-MYCN;Dbh-iCre tumors were syntenic to those observed in human neuroblastomas. Treatment of a cell line established from a tumor derived from a LSL-MYCN;Dbh-iCre mouse with JQ1 or MLN8237 reduced cell viability and demonstrated oncogene addiction to MYCN. Here we report establishment of the first Cre-conditional human MYCN-driven mouse model for neuroblastoma that closely recapitulates the human disease with respect to tumor localization, histology, marker expression and genomic make up. This mouse model is a valuable tool for further functional studies and to assess the effect of targeted therapies.

MYCN and ALKF1174L are sufficient to drive neuroblastoma development from neural crest progenitor cells.

Neuroblastoma is an embryonal tumor with a heterogeneous clinical course. The tumor is presumed to be derived from the neural crest, but the cells of origin remain to be determined. To date, few recurrent genetic changes contributing to neuroblastoma formation, such as amplification of the MYCN oncogene and activating mutations of the ALK oncogene, have been identified. The possibility to model neuroblastoma in mice allows investigation of the cell of origin hypothesis in further detail. Here we present the evidence that murine neural crest progenitor cells can give rise to neuroblastoma upon transformation with MYCN or ALK(F1174L). For this purpose we used JoMa1, a multipotent neural crest progenitor cell line, which is kept in a viable and undifferentiated state by a tamoxifen-activated c-Myc transgene (c-MycER(T)). Expression of MYCN or ALK(F1174L), one of the oncogenic ALK variants identified in primary neuroblastomas, enabled these cells to grow independently of c-MycER(T) activity in vitro and caused formation of neuroblastoma-like tumors in vivo in contrast to parental JoMa1 cells and JoMa1 cells-expressing TrkA or GFP. Tumorigenicity was enhanced upon serial transplantation of tumor-derived cells, and tumor cells remained susceptible to the MYC-inhibitor, NBT-272, indicating that cell growth depended on functional MYCN. Our findings support neural crest progenitor cells as the precursor cells of neuroblastoma, and indicate that neuroblastomas arise as their malignant progeny.

Lysine-specific demethylase 1 restricts hematopoietic progenitor proliferation and is essential for terminal differentiation.

Lysine (K)-specific demethylase 1A (LSD1/KDM1A) has been identified as a potential therapeutic target in solid cancers and more recently in acute myeloid leukemia. However, the potential side effects of a LSD1-inhibitory therapy remain elusive. Here, we show, with a newly established conditional in vivo knockdown model, that LSD1 represents a central regulator of hematopoietic stem and progenitor cells. LSD1 knockdown (LSD1-kd) expanded progenitor numbers by enhancing their proliferative behavior. LSD1-kd led to an extensive expansion of granulomonocytic, erythroid and megakaryocytic progenitors. In contrast, terminal granulopoiesis, erythropoiesis and platelet production were severely inhibited. The only exception was monopoiesis, which was promoted by LSD1 deficiency. Importantly, we showed that peripheral blood granulocytopenia, monocytosis, anemia and thrombocytopenia were reversible after LSD1-kd termination. Extramedullary splenic hematopoiesis contributed to the phenotypic reversion, and progenitor populations remained expanded. LSD1-kd was associated with the upregulation of key hematopoietic genes, including Gfi1b, Hoxa9 and Meis1, which are known regulators of the HSC/progenitor compartment. We also demonstrated that LSD1-kd abrogated Gfi1b-negative autoregulation by crossing LSD1-kd with Gfi1b:GFP mice. Taken together, our findings distinguish LSD1 as a critical regulator of hematopoiesis and point to severe, but reversible, side effects of a LSD1-targeted therapy.

Marked low-density lipoprotein cholesterol reduction below current national cholesterol education program targets provides the greatest reduction in carotid atherosclerosis.

BACKGROUND: Current National Cholesterol Education Program (NCEP) guidelines recognize low-density lipoprotein cholesterol (LDL-C) below 100 mg/dl as an optimal level. Evidence supporting this is scant. Both LDL-C and C reactive protein (CRP) are known correlates of atherosclerosis progression. HYPOTHESIS: We examined the effect of final LDL-C and CRP obtained with statin therapy on carotid intima-media thickness (CIMT), a valid surrogate for clinical benefit of lipid-lowering therapies. METHODS: In a randomized, single-center trial, 161 patients were assigned to statin therapy of different potencies (pravastatin 40 mg, n = 82; atorvastatin 80 mg, n = 79). The effects on CIMT were assessed in relationship to LDL-C and CRP levels obtained after 12 months of therapy. RESULTS: Changes in CIMT were directly related to the final LDL-C level obtained on statin therapy after 12 months (R = 0.219, p = 0.015). Carotid intima-media thickness regression was seen in 61% of the subjects in the lowest quartile of final LDL-C (< 70 mg/dl) versus 29% of the subjects with the highest quartile of final LDL-C (> or = 114 mg/dl, p = 0.008). No threshold value was seen, with more favorable effects on absolute change in CIMT with lower values of LDL-C (decrease in CIMT of 0.06 +/- 0.17 mm in the lowest quartile compared with an increase of 0.06 +/- 0.09 in the highest quartile of LDL-C, p = 0.008). On-treatment LDL and CRP concentrations both below the group median values were associated with the greatest likelihood of CIMT regression. CONCLUSIONS: Regression of carotid atherosclerosis is directly related to the absolute LDL-C level on statin therapy. The greatest regression was obtained with an LDL-C < 70 mg/dl, supporting marked LDL-C reduction to levels below current NCEP guidelines.

Chronotropic incompetence in a young adult: case report and literature review.

Chronotropic incompetence (CI) is the inability of heart rate response to meet metabolic demand. CI is associated with sinus node dysfunction, atrial fibrillation, or structural heart disease, and can lead to functional impairment. We report the case of a 34-year-old man with CI secondary to sinus node dysfunction who demonstrated significant improvement in functional capacity with rate-responsive pacing. Therapy for CI should be guided by the treatment of the underlying cause with consideration for rate-responsive pacing in symptomatic patients. The prognosis of CI is variable and dependent on underlying etiology.

Effect of atorvastatin and pravastatin on serum C-reactive protein.

BACKGROUND: Extra-lipid effects of statins, such as anti-inflammatory actions, may contribute to their clinical benefit. These effects, with important implications for the concept of a statin "class effect," may be drug specific or may be related to the extent of lipid lowering. METHODS: We randomized 130 patients to treatment with either atorvastatin (80 mg daily, n = 63) or pravastatin (40 mg daily, n = 67), and measured serum lipids, C-reactive protein, and fibrinogen at baseline and after 3 months of therapy. RESULTS: Mean C-reactive protein (CRP) levels were significantly reduced in both groups, with a 36% reduction in the atorvastatin group (0.39 +/- 0.36 to 0.25 +/- 0.27, P =.001) and a 22% reduction observed in the pravastatin group (0.40 +/- 0.33 to 0.31 +/- 0.32, P =.003). A reduced or unchanged CRP level was seen in 67.2% of pravastatin-treated patients (45/67) and 73% of atorvastatin- treated patients (46/63) (P =.47). There was no difference between drugs in either the absolute or relative reductions in CRP levels. However, whereas the reduction of CRP with pravastatin was unrelated to the degree of low-density lipoprotein reduction (r = -.05, P =.69), atorvastatin-induced CRP reductions correlated directly to the change in low-density lipoprotein-C (r =.33, P =.009). CONCLUSIONS: High-dose atorvastatin and pravastatin both reduce CRP levels. However, whereas pravastatin's effect on CRP is independent of lipid-lowering efficacy, these data suggest that lipid-dependent mechanisms are, at least in part, active in atorvastatin-treated patients.

ARBITER: Arterial Biology for the Investigation of the Treatment Effects of Reducing Cholesterol: a randomized trial comparing the effects of atorvastatin and pravastatin on carotid intima medial thickness.

BACKGROUND: Whether marked LDL reduction to levels well below 100 mg/dL would further reduce the burden of cardiovascular disease is controversial. We compared the effects of 2 statins with widely differing potencies for LDL reduction (pravastatin 40 mg/d and atorvastatin 80 mg/d) on carotid intima-media thickness (CIMT). METHODS AND RESULTS: This was a single-center, randomized, clinical trial of 161 patients (mean age, 60 years; 71.4% male; 46% with known cardiovascular disease) that met National Cholesterol Education Program (NCEP) II criteria for lipid-lowering therapy. The effects of atorvastatin (80 mg/d; n=79) and pravastatin (40 mg/d; n=82) on CIMT were compared using blinded, serial assessments of the far wall of the distal common carotid artery. Baseline CIMT and other characteristics were similar between study groups. As anticipated, atorvastatin was substantially more potent for LDL reduction after 12 months: in the atorvastatin group, LDL cholesterol was 76+/-23 mg/dL after 12 months (-48.5%); LDL cholesterol was 110+/-30 mg/dL in the pravastatin group (-27.2%; P<0.001). Atorvastatin induced progressive CIMT regression over 12 months (change in CIMT, -0.034+/-0.021 mm), whereas CIMT was stable in the pravastatin group (change of 0.025+/- 0.017 mm; P=0.03). CONCLUSIONS: Marked LDL reduction (<100 mg/dL) with a high-potency statin provides superior efficacy for atherosclerosis regression at 1 year. This early effect on CIMT, a surrogate for clinical benefit, suggests that marked LDL reduction with synthetic statins may provide enhanced reduction in clinical coronary event rates.