Spatial frequency-based correction of the spherical aberration in living brain imaging.

Optical errors, including spherical aberrations, hinder high-resolution imaging of biological samples due to biochemical components and physical properties. We developed the Deep-C microscope system to achieve aberration-free images, employing a motorized correction collar and contrast-based calculations. However, current contrast-maximization techniques, such as the Brenner gradient method, inadequately assess specific frequency bands. The Peak-C method addresses this issue, but its arbitrary neighbor selection and susceptibility to the noise limit its effectiveness. In this paper, we emphasize the importance of a broad spatial frequency range for accurate spherical aberration correction and propose Peak-F. This spatial frequency-based system utilizes a fast Fourier transform as a bandpass filter. This approach overcomes Peak-C's limitations and comprehensively covers the low-frequency domain of image spatial frequencies.

A spherical aberration-free microscopy system for live brain imaging.

The high-resolution in vivo imaging of mouse brain for quantitative analysis of fine structures, such as dendritic spines, requires objectives with high numerical apertures (NAs) and long working distances (WDs). However, this imaging approach is often hampered by spherical aberration (SA) that results from the mismatch of refractive indices in the optical path and becomes more severe with increasing depth of target from the brain surface. Whereas a revolving objective correction collar has been designed to compensate SA, its adjustment requires manual operation and is inevitably accompanied by considerable focal shift, making it difficult to acquire the best image of a given fluorescent object. To solve the problems, we have created an objective-attached device and formulated a fast iterative algorithm for the realization of an automatic SA compensation system. The device coordinates the collar rotation and the Z-position of an objective, enabling correction collar adjustment while stably focusing on a target. The algorithm provides the best adjustment on the basis of the calculated contrast of acquired images. Together, they enable the system to compensate SA at a given depth. As proof of concept, we applied the SA compensation system to in vivo two-photon imaging with a 25 × water-immersion objective (NA, 1.05; WD, 2 mm). It effectively reduced SA regardless of location, allowing quantitative and reproducible analysis of fine structures of YFP-labeled neurons in the mouse cerebral cortical layers. Interestingly, although the cortical structure was optically heterogeneous along the z-axis, the refractive index of each layer could be assessed on the basis of the compensation degree. It was also possible to make fully corrected three-dimensional reconstructions of YFP-labeled neurons in live brain samples. Our SA compensation system, called Deep-C, is expected to bring out the best in all correction-collar-equipped objectives for imaging deep regions of heterogeneous tissues.

Myocardium-derived angiopoietin-1 is essential for coronary vein formation in the developing heart.

The origin and developmental mechanisms underlying coronary vessels are not fully elucidated. Here we show that myocardium-derived angiopoietin-1 (Ang1) is essential for coronary vein formation in the developing heart. Cardiomyocyte-specific Ang1 deletion results in defective formation of the subepicardial coronary veins, but had no significant effect on the formation of intramyocardial coronary arteries. The endothelial cells (ECs) of the sinus venosus (SV) are heterogeneous population, composed of APJ-positive and APJ-negative ECs. Among these, the APJ-negative ECs migrate from the SV into the atrial and ventricular myocardium in Ang1-dependent manner. In addition, Ang1 may positively regulate venous differentiation of the subepicardial APJ-negative ECs in the heart. Consistently, in vitro experiments show that Ang1 indeed promotes venous differentiation of the immature ECs. Collectively, our results indicate that myocardial Ang1 positively regulates coronary vein formation presumably by promoting the proliferation, migration and differentiation of immature ECs derived from the SV.

Tocilizumab for the treatment of patients with refractory Takayasu arteritis.

Treatment of refractory Takayasu arteritis (TA) remains an unresolved clinical issue. Patients usually respond to glucocorticoid (GC) therapy, but often relapse on tapering of the GC dose. The aim of the present study was to assess the safety and efficacy of the interleukin-6 (IL-6) receptor antibody tocilizumab (TCZ) in patients with TA refractory to conventional therapies including GC. Four patients with TA who had shown GC resistance received TCZ infusions (8 mg/kg) every 4 weeks a total of at least 24 times (range, 24 to 51). Clinical symptoms, the serum levels of acute phase proteins and IL-6, GC dosage necessary to maintain remission, and cross-sectional imaging by enhanced CT and MRI were assessed. All patients achieved good clinical response and rapid normalization of the acute phase proteins such as C-reactive protein and serum amyloid A during the therapy with TCZ. The mean dosage of prednisolone could be reduced from 21.3 mg/day to 1.5 mg/day. Although the serum IL-6 level was transiently elevated in all patients after several TCZ infusions, it gradually recovered to the initial level. Along with the decrease of serum IL-6, two patients exhibited significant reduction in thickened arterial lesions. No drug-related adverse effects were noted. In this small group of patients with refractory TA, TCZ therapy was effective and well-tolerated. Further larger studies should be conducted to confirm this finding.

Endothelial Gab1 deletion accelerates angiotensin II-dependent vascular inflammation and atherosclerosis in apolipoprotein E knockout mice.

BACKGROUND: Docking protein Grb2-associated binder 1 (Gab1) has critical roles in signal transduction of various growth factors, cytokines, and numerous other molecules. Our previous reports show that Gab1 is essential for postnatal angiogenesis through the analysis of endothelium-specific Gab1 knockout (Gab1ECKO) mice. However, the role of Gab1 in atherosclerosis remains unknown. The aim of the present study was to elucidate the role of endothelial Gab1 in vascular inflammation and atherosclerosis. METHODS AND RESULTS: We intercrossed Gab1ECKO mice with apolipoprotein E (ApoE) knockout (ApoEKO) mice. Six-month-old male ApoEKO/Gab1ECKO and littermate control (ApoEKO) mice were treated with angiotensin II (AngII) via an osmotic infusion mini-pump. After AngII treatment, ApoEKO/Gab1ECKO mice showed significantly enhanced atherosclerosis and aneurysm formation compared with control mice. The production of proinflammatory cytokines in the aorta was significantly enhanced in ApoEKO/Gab1ECKO mice compared with control mice. Furthermore, the expression levels of Krüppel-like factor (KLF) 2 (KLF2) and KLF4, key transcription factors for endothelial homeostasis, were significantly reduced in the aortic endothelium of ApoEKO/Gab1ECKO mice compared with those of control mice. Consistently, both vascular cell adhesion molecule-1 expression and macrophage infiltration on the aortic walls were enhanced in ApoEKO/Gab1ECKO mice compared with control mice. CONCLUSIONS: Collectively, endothelial Gab1 deletion accelerates AngII-dependent vascular inflammation and atherosclerosis on ApoE-null background presumably in association with downregulation of KLF2 and KLF4.

Docking protein Gab1 is an essential component of postnatal angiogenesis after ischemia via HGF/c-met signaling.

RATIONALE: Grb2-associated binder (Gab) docking proteins, consisting of Gab1, Gab2, and Gab3, have crucial roles in growth factor-dependent signaling. Various proangiogenic growth factors regulate angiogenesis and endothelial function. However, the roles of Gab proteins in angiogenesis remain elusive. OBJECTIVE: To elucidate the role of Gab proteins in postnatal angiogenesis. METHODS AND RESULTS: Endothelium-specific Gab1 knockout (Gab1ECKO) mice were viable and showed no obvious defects in vascular development. Therefore, we analyzed a hindlimb ischemia (HLI) model of control, Gab1ECKO, or conventional Gab2 knockout (Gab2KO) mice. Intriguingly, impaired blood flow recovery and necrosis in the operated limb was observed in all of Gab1ECKO, but not in control or Gab2KO mice. Among several proangiogenic growth factors, hepatocyte growth factor (HGF) induced the most prominent tyrosine phosphorylation of Gab1 and subsequent complex formation of Gab1 with SHP2 (Src homology-2-containing protein tyrosine phosphatase 2) and phosphatidylinositol 3-kinase subunit p85 in human endothelial cells (ECs). Gab1-SHP2 complex was required for HGF-induced migration and proliferation of ECs via extracellular signal-regulated kinase (ERK)1/2 pathway and for HGF-induced stabilization of ECs via ERK5. In contrast, Gab1-p85 complex regulated activation of AKT and contributed partially to migration of ECs after HGF stimulation. Microarray analysis demonstrated that HGF upregulated angiogenesis-related genes such as KLF2 (Krüppel-like factor 2) and Egr1 (early growth response 1) via Gab1-SHP2 complex in human ECs. In Gab1ECKO mice, gene transfer of vascular endothelial growth factor, but not HGF, improved blood flow recovery and ameliorated limb necrosis after HLI. CONCLUSION: Gab1 is essential for postnatal angiogenesis after ischemia via HGF/c-Met signaling.

The efficacy of tocilizumab in a patient with pulmonary arterial hypertension associated with Castleman's disease.

Castleman's disease is a highly heterogeneous clinical-pathological entity that belongs to the lymphoproliferative disorders and is associated with pulmonary arterial hypertension (PAH) in some patients. It is linked to excessive immune stimulation by interleukin-6 (IL-6), which is also involved in the pathogenesis of PAH. A 31-year-old woman with Castleman's disease demonstrated PAH characterized by severe right heart failure. Since she was resistant to various conventional therapies including steroids, prostacyclins, bosentan, and sildenafil, tocilizumab (anti-IL-6 receptor antibody) therapy was started. Her clinical course was followed for 6 months, with significant improvement without any adverse effect. This is the first reported case of use of tocilizumab in addition to steroids and conventional PAH therapy in a patient with PAH associated with Castleman's disease.

SHP2 mediates gp130-dependent cardiomyocyte hypertrophy via negative regulation of skeletal alpha-actin gene.

Morphological and biochemical phenotypes of cardiomyocyte hypertrophy are determined by neurohumoral factors. Stimulation of G protein-coupled receptor (GPCR) results in uniform cell enlargement in all directions with an increase in skeletal alpha-actin (alpha-SKA) gene expression, while stimulation of gp130 receptor by interleukin-6 (IL-6)-related cytokines induces longitudinal elongation with no increase in alpha-SKA gene expression. Thus, alpha-SKA is a discriminating marker for hypertrophic phenotypes; however, regulatory mechanisms of alpha-SKA gene expression remain unknown. Here, we clarified the role of SH2-containing protein tyrosine phosphatase 2 (SHP2) in alpha-SKA gene expression. In neonatal rat cardiomyocytes, endothelin-1 (ET-1), a GPCR agonist, but not leukemia inhibitory factor (LIF), an IL-6-related cytokine, induced RhoA activation and promotes alpha-SKA gene expression via RhoA. In contrast, LIF, but not ET-1, induced activation of SHP2 in cardiomyocytes, suggesting that SHP2 might negatively regulate alpha-SKA gene expression downstream of gp130. Therefore, we examined the effect of adenovirus-mediated overexpression of wild-type SHP2 (SHP2(WT)), dominant-negative SHP2 (SHP2(C/S)), or beta-galactosidase (beta-gal), on alpha-SKA gene expression. LIF did not upregulate alpha-SKA mRNA in cardiomyocytes overexpressing either beta-gal or SHP2(WT). In cardiomyocytes overexpressing SHP2(C/S), LIF induced upregulation of alpha-SKA mRNA, which was abrogated by concomitant overexpression of either C3-toxin or dominant-negative RhoA. RhoA was activated after LIF stimulation in the cardiomyocytes overexpressing SHP2(C/S), but not in myocytes overexpressing beta-gal. Furthermore, SHP2 mediates LIF-induced longitudinal elongation of cardiomyocytes via ERK5 activation. Collectively, these findings indicate that SHP2 negatively regulates alpha-SKA expression via RhoA inactivation and suggest that SHP2 implicates ERK5 in cardiomyocyte elongation downstream of gp130.

Clinical significance of plasma endothelin-1 level after bosentan administration in pulmonary arterial hypertension.

BACKGROUND: Endothelin (ET)-1 has been shown to play a significant pathogenic role in pulmonary arterial hypertension (PAH). However, the pathobiological significance of increased ET-1 concentration after administration of ET receptor antagonist in patients with PAH has not yet been fully examined. METHODS: In 16 PAH patients, plasma ET-1 concentration was measured at 0, 1, 3, 6, and 24h after a single 62.5mg dose of bosentan, a dual ET receptor antagonist, and the peak and 24-h change in ET-1 concentration from baseline were examined. The severity of PAH was evaluated by hemodynamic parameters, 6-min walk distance, New York Heart Association (NYHA) functional class, and brain natriuretic peptide (BNP). RESULTS: Plasma ET-1 concentration significantly increased from 1.93+/-0.12 to 3.36+/-0.18 pg/ml after bosentan administration in PAH patients (p<0.01). The peak-to-baseline ratio of ET-1 concentration after bosentan administration showed a significant positive correlation with baseline ET-1 concentration (p<0.05). After 4-week bosentan administration, NYHA functional class improved in 7 patients but was not changed in 9 patients. The optimal cut-off point of % change of ET-1 concentration at 24h for discriminating the two groups was 30%. According to this cut-off point, patients were divided into the higher (n=7) and the lower (n=9) groups. NYHA functional class did not change in the lower group, but significantly improved (p<0.01) in the higher group after 4-week bosentan administration. In addition, plasma BNP levels significantly decreased from baseline in the higher group compared with those in the lower group after 12-week bosentan administration (-44+/-11% vs. 7+/-20%, p<0.05). CONCLUSIONS: Although the population in this study is small and heterogeneous, measurement of plasma ET-1 concentration after bosentan administration might predict the responsiveness to bosentan treatment, and be useful in the determination of effective therapy in treatment of PAH patients.

Single-nucleotide-polymorphism genotyping for whole-genome-amplified samples using automated fluorescence correlation spectroscopy.

Whole-genome amplification (WGA) methods were adopted for single-nucleotide-polymorphism (SNP) typing to minimize the amount of genomic DNA that has to be used in typing for thousands of different SNPs in large-scale studies; 5-10 ng of genomic DNA was amplified by a WGA method (improved primer-extension-preamplification-polymerase chain reaction (I-PEP-PCR), degenerated oligonucleotide primer-PCR (DOP-PCR), or multiple displacement amplification (MDA)). Using 1/100 to 1/500 amounts of the whole-genome-amplified products as templates, subsequent analyses were successfully performed. SNPs were genotyped by the sequence-specific primer (SSP)-PCR method followed by fluorescence correlation spectroscopy (FCS). The typing results were evaluated for four different SNPs on tumor necrosis factor receptor 1 and 2 genes (TNFR1 and TNFR2). The genotypes determined by the SSP-FCS method using the WGA products were 100% in concordance with those determined by nucleotide sequencing using genomic DNAs. We have already carried out typing of more than 300 different SNPs and are currently performing 7,500-10,000 typings per day using WGA samples from patients with several common diseases. WGA coupled with FCS allows specific and high-throughput genotyping of thousands of samples for thousands of different SNPs.