Enhancing the spatial resolution of time-of-flight based non-line-of-sight imaging via instrument response function deconvolution

Non-line-of-sight (NLOS) imaging retrieves the hidden scenes by utilizing the signals indirectly reflected by the relay wall. Benefiting from the picosecond-level timing accuracy, time-correlated single photon counting (TCSPC) based NLOS imaging can achieve theoretical spatial resolutions up to millimeter level. However, in practical applications, the total temporal resolution (also known as total time jitter, TTJ) of most current TCSPC systems exceeds hundreds of picoseconds due to the combined effects of multiple electronic devices, which restricts the underlying spatial resolution of NLOS imaging. In this paper, an instrument response function deconvolution (IRF-DC) method is proposed to overcome the constraints of a TCSPC system's TTJ on the spatial resolution of NLOS imaging. Specifically, we model the transient measurements as Poisson convolution process with the normalized IRF as convolution kernel, and solve the inverse problem with iterative deconvolution algorithm, which significantly improves the spatial resolution of NLOS imaging after reconstruction. Numerical simulations show that the IRF-DC facilitates light-cone transform and frequency-wavenumber migration solver to achieve successful reconstruction even when the system's TTJ reaches 1200 ps, which is equivalent to what was previously possible when TTJ was about 200 ps. In addition, the IRF-DC produces satisfactory reconstruction outcomes when the signal-to-noise ratio (SNR) is low. Furthermore, the effectiveness of the proposed method has also been experimentally verified. The proposed IRF-DC method is highly applicable and efficient, which may promote the development of high-resolution NLOS imaging.

Nobiletin inhibits breast cancer cell migration and invasion by suppressing the IL-6-induced ERK-STAT and JNK-c-JUN pathways

BACKGROUND

Breast cancer is one of the most common cancers in women, affecting more than 2 million women worldwide annually. However, effective treatments for breast cancer are limited. Nobiletin is a flavonoid present in the dried mature pericarp of mandarin orange (Citrus reticulata Blanco), which is used to prepare Citri Renetulatae Pericarpium and can inhibit tumour growth and progression according to modern pharmacological studies. However, whether nobiletin exhibits an antimetastatic role in breast cancer and its potential mechanism need to be further investigated.

PURPOSE

This study aims to evaluate the inhibitory effect of nobiletin on breast cancer and to elucidate potential mechanisms against invasion and migration.

METHODS

Cell viability was determined by cell counting kit-8 and colony formation assays. Wound healing and Boyden chamber assays detected cancer cell migration and invasion capabilities. Immunoblotting and qPCR were applied to determine the protein and mRNA expression levels of extracellular signal-regulated kinases (ERK) and the c-Jun N-terminal kinase (JNK) signalling pathways. Molecular docking was used to assess the degree of nobiletin binding to phosphatidylinositol 3-kinase (PI3K). Xenografts and liver metastases were constructed in BALB/c nude mice to evaluate the anticancer effect of nobiletin in vivo. H&E staining and immunohistochemistry were used to detect proliferation and the expression of related proteins.

RESULTS

Nobiletin induced cell death in a concentration- and time-dependent manner and possessed anti-invasion and anti-migration effects on MCF-7 and T47D cells by suppressing the interleukin-6-induced ERK and JNK signalling pathways. In addition, nobiletin docked with the binding site of PI3K, and the binding score was -8.0 kcal/mol. Furthermore, the inhibition of breast cancer growth and metastasis by nobiletin was demonstrated by constructing xenografts and liver metastases in vivo.

CONCLUSION

Nobiletin inhibited liver metastasis of breast cancer by downregulating the ERK-STAT and JNK-c-JUN pathways, and its safety and efficacy were verified, indicating the potential of nobiletin as an anticancer agent.

The mechanism of FZXJJZ decoction suppresses colorectal liver metastasis via the VDR/TGF-β/Snail1 signaling pathways based on network pharmacology-TCGA data-transcriptomics analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Fuzheng Xiaojijinzhan (FZXJJZF) decoction is an effective prescription for treating colorectal cancer liver metastasis (LMCRC).

AIM OF THE STUDY

To elucidate the pharmacological mechanism of the FZXJJZF decoction therapy on LMCRC.

MATERIALS AND METHODS

Firstly, a network pharmacological approach was used to characterize the underlying targets of FZXJJZF on LMCRC. Secondly, LMCRC-related genes are obtained from the public database TCGA, and those genes are further screened and clustered through Mfuzz, an R package tool. Then, targets of FZXJJZF predicted by network pharmacology were overlapped with LMCRC related genes screened by Mfuzz. Meanwhile, FZJZXJF intervened in LMCRC model,epithelial-to-mesenchymal transition (EMT), and migration and invasion of HCT-116 cells. Thirdly, the transcriptomics data of FZJZXJF inhibited HCT-116 cells of EMT cells were overlapped with EMT database data to narrow the possible range of targets. Based on this, the potential targets and signal pathways of FZJZXJF were speculated by combining the transcriptomics data with the targets from network pharmacology-TCGA. Finally, the anti-cancer mechanism of FZXJJZF on LMCRC was verified in vitro by Real-Time PCR and Western Blot in vitro.

RESULTS

By network pharmacological analysis, 282 ingredients and 429 potential targets of FZXJJZF were predicted. The 9268 LMCRC-related genes in the TCGA database were classified into 10 clusters by the Mfuzz. The two clustering genes with the most similar clustering trends were overlapped with 429 potential targets, and 32 genes were found, such as CD34, TRPV3, PGR, VDR, etc. In vivo experiments, FZJZXJF inhibited the tumor size in LMCRC models, and the EMT, migration, and invasion of HCT-116 also be inhibited. Intersecting transcriptomics dates with 32 target genes, it is speculated that the VDR-TGF-β signaling pathway may be an effective mechanism of FZXJJZF. Additionally, it is shown that FZXJJZF up-regulated the expression levels of VDR and E-cadherin and down-regulated the expression levels of TGF-β and Snail1 in vitro. These results confirmed that FZXJJZF plays an effective role in LMCRC mainly by inhibiting EMT phenotype via the VDR-TGF-β signaling pathway.

CONCLUSIONS

Collectively, this study reveals the anti-LMCRC effect of FZXJJZF and its potential therapeutic mechanism from the perspective of potential targets and potential pathways.

Effect of the Transition Metal Ions on the Single-Molecule Magnet Properties in a Family of Air-Stable 3d-4f Ion-Pair Compounds with Pentagonal Bipyramidal Ln(III) Ions

Single-molecule magnets (SMMs) are expected to be promising candidates for the applications of high-density information storage materials and quantum information processing. Lanthanide SMMs have attracted considerable interest in recent years due to their excellent performance. It has always been interesting but not straightforward to study the relaxation and blocking mechanisms by embedding 3d ions into 4f SMMs. Here we report a family of air-stable 3d-4f ion-pair compounds, YFe (1), DyCr (2), DyFe (3), DyCo (4), and Dy_0.04Y_0.96Fe (5), composed of pentagonal bipyramidal (D_5h) Ln^III cations and transition metallocyanate anions. The ion-pair nature makes the dipole-dipole interactions almost the only component of the magnetic interactions that can be clarified and analytically resolved under proper approximation. Therefore, this family provides an intuitive opportunity to investigate the effects of 3d-4f and 4f-4f magnetic interactions on the behavior of site-resolved 4f SMMs. Dynamic magnetic measurements of 1 under a 4 kOe external field reveal slow magnetic relaxation originating from the isolated [Fe^III]_LS (S = ¹/₂) ions. Under zero dc field, compounds 2-5 show similar magnetic relaxation processes coming from the separated pentagonal bipyramidal (D_5h) Dy^III ions with high Orbach barriers of 592(5), 596(4), 595(3), and 606(4) K, respectively. Comparatively, both compounds 3 and 5 exhibit two distinct relaxation processes, respectively from the [Fe^III]_LS and Dy^III [U_eff = 596(4) K for 3 and 610(7) K for 5] ions, under a 4 kOe dc field. The dipolar interactions between the neighboring TM^III (TM = transition metal, Cr^III or [Fe^III]_LS) and Dy^III ions were revealed to have little effect on the thermal relaxation in compounds 2, 3, and 5, or the coexistence of the two separate relaxation processes in compounds 3 and 5 under a 4 kOe dc field, but they significantly affect the quantum tunneling of magnetization and the magnetic hysteresis behavior of 2 and 3 at low temperatures compared to those of 4.

Research Progress on Accumulated Degree Days for PMI Estimation

Abstract

Among many factors that affect postmortem interval （PMI）, temperature is undoubtedly the most important factor, but simply considering temperature in estimation of PMI has limitations. Accumulated degree days （ADD） is an important indicator related to biological growth and development, which considers two major variables, environmental temperature and elapsed time. Therefore, the establishment of mathematical model of ADD and some evaluation indicators to estimate PMI, is obviously better than single temperature variable. This article briefly describes the research history of ADD, its application in PMI estimation, and the problems it faces, to provide reference for the further development of ADD to improve the accuracy of PMI estimation.

Sequential Changes of Total Adenine Nucleotide and Adenylic-Acid Energy Charge in Muscles of Rats after Death

Abstract

Objective To determine the purine adenylate [adenosine triphosphate （ATP）, adenosine diphosphate （ADP）, adenosine monophosphate （AMP）] content in the muscles of both hind limbs of rats at different postmortem interval （PMI）, calculate the changes in the total adenine nucleotide （TAN） content and the adenylic-acid energy charge （AEC）, and explore their relationship with PMI. Methods Healthy rats were sacrificed by cervical dislocation and kept at 20 ℃. The muscles of their hind limbs were extracted at 0, 24, 48, 72, 96, 120, 144, and 168 h after death. Reversed-phase high performance liquid chromatography was used to determine the content of purine adenylates, the TAN and AEC of the muscles of the both hind limbs were calculated, and the related regression equations of their relationship with PMI were established. Results Within 168 h of death of rats, the trend of ATP change was different from ADP, and the content of AMP continuously increased. The TAN value gradually increased with the extension of PMI, and the AEC showed a downward trend within 168 h after death. Among them, the patterns of AEC changes with PMI were obvious, the correlation coefficient was high （ R²=0.903）, and the curve fitting relationship was good; the fitting relationship between ATP, ADP, AMP, TAN and PMI was poor （ R²=0.198-0.754）. Conclusion The postmortem change patterns of AEC provide new research ideas for PMI estimation in the forensic field.

The comparative studies on the magnetic relaxation behaviour of the axially-elongated pentagonal-bipyramidal dysprosium and erbium ions in similar one-dimensional chain structures

A family of cyano-bridged 3d-4f 1D chain compounds, {RE[TM(CN)6(2-PNO)5]}·(H2O)4 {RE = YIII, TM = [FeIII]LS (1); RE = DyIII, TM = CoIII (3); RE = ErIII, TM = [FeIII]LS (4), CoIII (5); 2-PNO = 2-picoline-N-oxide} and {RE[TM(CN)6(2-PNO)5]} {RE = DyIII, TM = [FeIII]LS (2)}, were synthesized and characterized. Single-crystal X-ray diffraction studies reveal that compounds 1 and 3-5 are isostructural, while compound 2 has a similar 1D chain structure with a different chain to chain arrangement. An axially-elongated pentagonal bipyramidal (D5h) coordination geometry is formed with five 2-PNO ligands in the equatorial plane and two [TM(CN)6]3- on the apical sites around the rare earth ions in these compounds. A comparison of the magnetic relaxation behaviour in detail reveals that it is more favorable for the Er (4 and 5) than the Dy analogues (2 and 3) to exhibit SIM properties in this axially-elongated D5h coordination environment. Under zero dc field, ac susceptibility measurements show that the Dy analogues have no magnetic relaxation behaviour, while the Er analogues exhibit frequency dependence despite the strong QTM effect. Under a 1 kOe dc field, the Er analogues generally show 1-2 orders of magnitude longer relaxation time at each selected temperature and a higher relaxation energy barrier than the Dy analogues. And the RECo compounds (3 and 5) show a more suppressed QTM effect than the corresponding REFe (2 and 4) compounds, which may be ascribed to the elimination of the fluctuation field from the neighbouring [FeIII]LS ions. The ab initio calculations indicate the misplacement between the orientation of the main magnetic axis and the structural axis in the Dy analogues, and the relative consistency in the Er analogues, which should be the source of the Er analogues showing better SIM properties than the Dy analogues.

The differential magnetic relaxation behaviours of slightly distorted triangular dodecahedral dysprosium analogues in a type of cyano-bridged 3d–4f zig-zag chain compounds

Differential magnetic properties were observed for triangular dodecahedral dysprosium analogues in a type of cyano-bridged 3d–4f zig-zag chain compound.

Inhibition of ROCK activity regulates the balance of Th1, Th17 and Treg cells in myasthenia gravis

Aberrant ROCK activation has been found in patients with several autoimmune diseases, but the role of ROCK in myasthenia gravis (MG) has not yet been clearly investigated. Here, we demonstrated that ROCK activity was significantly higher in peripheral blood mononuclear cells (PBMCs) from MG patients. ROCK inhibitor Fasudil down-regulated the proportions of Th1 and Th17 cells in PBMCs of MG patients in vitro. Intraperitoneal injection of Fasudil ameliorated the severity of experimental autoimmune myasthenia gravis (EAMG) rats and restored the balance of Th1/Th2/Th17/Treg subsets. Furthermore, Fasudil inhibited the proliferation of antigen-specific Th1 and Th17 cells, and inhibited CD4 + T cells differentiated into Th1 and Th17 through decreasing phosphorylated Stat1 and Stat3, but promoted Treg cell differentiation through increasing phosphorylated Stat5. We conclude that dysregulated ROCK activity may be involved in the pathogenic immune response of MG and inhibition of ROCK activity might serve as a novel treatment strategy for MG.

[Association between the accumulation of metabolic syndrome abnormal components and arterial pulse wave velocity among adult individuals undergoing routine health examination]

Objective: To explore the association between the accumulation of metabolic syndrome (MS) components and abnormal brachial ankle pulse wave velocity (baPWV), and to investigate the effect of accumulation of abnormal metabolic components on abnormal baPWV among adult individuals undergoing routine health examination. Methods: It's a cross-sectional study. Data from 9 201 stratified sampled subjects, aged between 25 to 75 years old, who took part in the annual health checkups in 11 cities of Zhejiang Province from January to December 2016, were analyzed. Blood pressure(BP), fasting plasma glucose(FPG), waist circumference(WC), triglyceride(TG), high-density lipoprotein cholesterols(HDL-C) were defined as MS components. The baPWV was measured by VP-1000 (BP-203RPE Ⅲ) and ΔbaPWV (measured baPWV-reference baPWV/reference baPWV) ×100 (%)> 10% was defined as abnormal. The relationship between MS components and ΔbaPWV was analyzed by linear regression, and impact of accumulation of MS components on ΔbaPWV was analyzed by logistic regression, and the ΔbaPWV in subjects with different levels of MS components were analyzed by analysis of variance. Results: (1) The linear regression analysis demonstrated a positive correlation between ΔbaPWV and MS components including systolic blood pressure, diastolic blood pressure, WC, FPG, TG, while ΔbaPWV was negatively correlated with HDL-C. The β values were 0.518, 0.616, 0.208, 2.778, 1.862, -1.339, respectively (all P<0.001), indicating a strong association between ΔbaPWV and systolic blood pressure, diastolic blood pressure, and FPG. (2) The logistic regression analysis showed that the proportion of abnormal ΔbaPWV was 2.595 times higher in MS individuals than in non-MS individuals (P<0.001). Abnormal ΔbaPWV increased in proportion with increase in numbers of the metabolic components (OR=1.913, 2.884, 3.833, 6.161, 11.176 in individuals with 1,2,3,4,5 metabolic components, respectively, all P<0.001). (3) The logistic analysis suggested that each component of MS could affect baPWV,and OR was 4.68, 2.45 for systolic blood pressure and/or diastolic blood pressure and FPG. All combinations of 2 components of MS also significantly affected baPWV,and OR value was the highest (5.104(95%CI 4.281-6.085), P<0.001) for FPG+BP. All combinations of 3 components of MS significantly affected baPWV,and OR value was the highest(5.385(95%CI 4.245-6.831), P<0.001) for BP+FPG+TG. All combinations of 4 components of MS affected baPWV,and OR value was the highest (6.519(95%CI 4.731-8.984), P<0.001) for BP+FPG+WC+TG. (4) Finally, every component of MS was divided into 3 levels, their impact on abnormal ΔbaPWV was analyzed. Prevalence of abnormal ΔbaPWV significantly increased with the increasing levels of the metabolic components expect for HDL-C, the F values were 1 224.66, 832.89, 192.72, 112.79 and 56.22, respectively (all P<0.001), indicating that higher levels of metabolic components significantly affected the ΔbaPWV. Conclusions: MS and accumulation of abnormal MS components are closely related with abnormal ΔbaPWV, and the combination of BP and FPG have the greatest impact on the abnormal ΔbaPWV. Analysis on the accumulation of MS components might serve as an early indicator of arteriosclerosis.

[Technical specification for clinical application of critical ultrasonography]

Critical ultrasonography(CUS) is different from the traditional diagnostic ultrasound, the examiner and interpreter of the image are critical care medicine physicians. The core content of CUS is to evaluate the pathophysiological changes of organs and systems and etiology changes. With the idea of critical care medicine as the soul, it can integrate the above information and clinical information, bedside real-time diagnosis and titration treatment, and evaluate the therapeutic effect so as to improve the outcome. CUS is a traditional technique which is applied as a new application method. The consensus of experts on critical ultrasonography in China released in 2016 put forward consensus suggestions on the concept, implementation and application of CUS. It should be further emphasized that the accurate and objective assessment and implementation of CUS requires the standardization of ultrasound image acquisition and the need to establish a CUS procedure. At the same time, the standardized training for CUS accepted by critical care medicine physicians requires the application of technical specifications, and the establishment of technical specifications is the basis for the quality control and continuous improvement of CUS. Chinese Critical Ultrasound Study Group and Critical Hemodynamic Therapy Collabration Group, based on the rich experience of clinical practice in critical care and research, combined with the essence of CUS, to learn the traditional ultrasonic essence, established the clinical application technical specifications of CUS, including in five parts: basic view and relevant indicators to obtain in CUS; basic norms for viscera organ assessment and special assessment; standardized processes and systematic inspection programs; examples of CUS applications; CUS training and the application of qualification certification. The establishment of applied technology standard is helpful for standardized training and clinical correct implementation. It is helpful for clinical evaluation and correct guidance treatment, and is also helpful for quality control and continuous improvement of CUS application.

Investigating the relationship between 25-hydroxyvitamin D and thyroid function in second-trimester pregnant women

This study aims to explore the correlation between serum 25-hydroxyvitamin D and thyroid hormones during the second trimester. In total, 277 pregnant women at 13-28 weeks of gestation were enrolled. According to the level of thyrotropic-stimulating hormone, they were divided into a reduced TSH group, a normal TSH group and an elevated TSH group. In this study, we found that the prevalence of vitamin D deficiency was as high as 94.58%. The 25-hydroxyvitamin D level in the reduced TSH group was lower than that in the normal thyroid function group (p = .0005), and the 25-hydroxyvitamin D level in the elevated TSH group was higher than that in normal TSH group (p=.0339). A positive correlation was observed between 25-hydroxyvitamin D and thyrotropic-stimulating hormone (r = 0.3034, p = .0000). Furthermore, 25-hydroxyvitamin D was negatively correlated with the free thyroxine level (r = -0.1286, p = .0323) as well as the free triiodothyronine level (r = 0.1247, p = .0380). These data suggest that the relationships between 25-hydroxyvitamin D and thyroid parameters were characterized during the second trimester. Pregnant women in the second-trimester who are diagnosed with transient hyperthyroidism should be evaluated for the possibility of vitamin D deficiency.

Nonalcoholic fatty liver was associated with asymptomatic gallstones in a Chinese population

The aim of this study was to determine the association between nonalcoholic fatty liver disease (NAFLD) and asymptomatic gallstones in a Chinese population.The study had a cross-sectional design and enrolled 7583 subjects who visited the physical check-up center at Sir Run Run Shaw Hospital between 2009 and 2011. Colorimetric methods were used to measure the levels of cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), whereas fasting plasma glucose (FPG) level was measured using a dextrose-oxidizing enzyme method. Subjects who completed a questionnaire and underwent a medical and ultrasound examinations were included in the study.The prevalence of NAFLD was significantly higher in patients with asymptomatic gallstones than in those without asymptomatic gallstones (58.98% vs 46.58%, respectively; P < .0001). The age-adjusted odds ratio (OR) for NAFLD being accompanied by asymptomatic gallstones was 1.35 [95% confidence interval (CI), 1.13-1.61; P = .0009] in male and 1.92 (95% CI, 1.45-2.54; P < .0001) in female subjects. Asymptomatic gallstones were associated with NAFLD in subjects aged < 50 years (OR = 1.74, 95% CI, 1.44-2.12; P < .0001), but not in subjects aged > 50 years (OR = 1.17, 95% CI, 0.92-1.48; P = .2040). The OR of NAFLD for asymptomatic gallstones was 1.28 after multivariate logistic regression analysis (95% CI, 1.07-1.52; P = .006).Our results indicated that asymptomatic gallstones are strongly associated with NAFLD in the Chinese study population.

Optically pumped lasing with a Q-factor exceeding 6000 from wet-etched GaN micro-pyramids

We report the observation of room-temperature optically pumped lasing modes from a single GaN pyramid microcavity on a metallic mirror. The mode at 367.2 nm exhibits a low threshold (0.4-0.5  MW/cm²) and a narrow linewidth (0.054 nm), by which the quality factor can be estimated to be >6000. These lasing behaviors can be attributed to the specific wet-etching approach by selectively etching away defects and pyramid geometry with bottom Ag reflectors for better light confinement. Optical resonances in these pyramids are further investigated in combination with three-dimensional finite-difference time-domain simulations.

A family of one-dimensional lanthanide complexes bridged by two distinct carboxylate ligands with the Dy analogue displaying magnetic relaxation behaviour

Utilizing two different carboxylate ligands to construct dysprosium SMMs with relatively good performance was proven to be a successful synthetic strategy.

A putative mechanism on remission of multiple sclerosis during pregnancy: estrogen-induced indoleamine 2,3-dioxygenase by dendritic cells

The basis for the reduced relapse rate of multiple sclerosis (MS) during pregnancy remains unexplained but, if defined, could create novel treatment options. Estrogen constitutes one candidate molecule, but the mechanism by which estrogen may affect MS during pregnancy is unclear. In this study, we used monocyte-derived dendritic cells (DCs) from MS patients to explore the estrogen (17-b-estradiol)-related pathway of immune modulation. Estrogen induced the expression of indoleamine 2,3-dioxygenase (IDO) on DCs, limiting T-cell proliferation and both Th1 and Th2 cytokine production. The suppression of T-cell proliferation mediated by estrogenexposed DCs was partly abolished by the IDO-inhibitor, 1-methyl-dl-tryptophan, indicating that estrogen-exposed DCs induced IDO-dependent T-cell suppression. Our data support the hypothesis that the change in the clinical course of MS observed in pregnancy may be related to the estrogen DC-IDO axis, which could represent a novel target for MS therapy.

Correlation between B type natriuretic peptide and metabolic risk factors

INTRODUCTION

It has been shown that B type natriuretic peptide (BNP) level can indicate cardiovascular disease. However, the association between BNP and metabolic risk factors is unknown. The aim of this study was to investigate the correlation between N-terminal pro-B type natriuretic peptide (NT-proBNP) and metabolic risk factors.

MATERIAL AND METHODS

A total of 11,508 subjects were selected from those who underwent health examinations in our hospital. NT-proBNP, waist circumference, blood pressure, fasting plasma glucose and lipid profile were measured. The level of NT-proBNP was measured and classified into four stratifications (BNP ≥ 20 pg/ml, ≥ 40 pg/ml, ≥ 60 pg/ml, and ≥ 80 pg/ml) to analyze the relationship between BNP and metabolic risk factors.

RESULTS

B type natriuretic peptide increased gradually with increasing age (p < 0.001). The BNP levels were significantly higher in women than in men (p < 0.001). Multivariate regression analysis showed a positive association between NT-proBNP levels and systolic blood pressure (p < 0.001), fasting plasma glucose (p < 0.05), and total cholesterol (p < 0.001 in women). The NT-proBNP levels were inversely associated with diastolic blood pressure, waist circumference, triglyceride, high-density lipoprotein, and LDL cholesterol. Logistic regression analysis demonstrated a close relationship between NT-proBNP and systolic blood pressure, fasting plasma glucose, and total cholesterol. In the BNP ≥ 60 pg/ml group, odds ratio (OR) values were 1.80, 1.56 and 1.54 (female) and 3.74, 1.59 and 1.51 (male), respectively. In the BNP ≥ 80 pg/ml group, OR values were 2.45, 1.65 and 1.84 (female) and 4.61, 1.66 and 1.75 (male), respectively.

CONCLUSIONS

NT-proBNP was independently associated with the main metabolic risk factors (systolic blood pressure, fasting plasma glucose, and total cholesterol). These findings suggest that the combined determination of NT-proBNP and the main metabolic risk factors could be important in assessing cardiovascular morbidity.

Lanthanide dinuclear complexes constructed from mixed oxygen-donor ligands: the effect of substituent positions of the neutral ligand on the magnetic dynamics in Dy analogues

Two series of lanthanide dinuclear complexes with the general formulae, [Ln(n-PNO)(Bza)3(H2O)] {Bza = benzoic acid; n = 3, n-PNO = 3-picoline N-oxide, Dy(1) and Er(2); and n = 4, n-PNO = 4-picoline N-oxide, Nd(3), Eu(4), Gd(5), Tb(6), Dy(7), Er(8) and Y(9)} have been successfully synthesized by the hydrothermal method. Single-crystal X-ray diffraction experiments illustrate that the two series of compounds possess similar carboxylic ligand-bridged dinuclear structure and coordination geometry around the lanthanide ions despite the different methyl-substituent positions on the neutral ligand. Comparative studies of the Dy analogues in the static-field measurements reveal only a little difference with a small butterfly-shaped opening for complex 1 and a close hysteresis loop for 7 at 2.0 K. However, systematic investigations of the alternating-current (ac) measurements indicate that the different substituent positions of the picoline N-oxide ligand have a significant effect on the magnetic relaxation dynamics. A more substantial suppression of the quantum tunnelling of magnetization (QTM) effect and pronounced slow magnetic relaxation were observed in complex 7 as compared to 1 under both zero and a 1 kOe static field.

A multifunctional lanthanide metal–organic framework supported by Keggin type polyoxometalates

An unusual multifunctional POM@MOF neodymium metal–organic framework with 1D nanotubular channels incorporating Keggin type [SiWV3WVI9O₃₈]³⁻ polyoxometalates was successfully synthesized.

Correlation between non-alcoholic fatty liver with metabolic risk factors and brachial-ankle pulse wave velocity

AIM: To assess the relationship between non-alcoholic fatty liver disease (NAFLD) with metabolic risk factors and brachial ankle pulse wave velocity (baPWV).

METHODS: A total of 8603 subjects (6662 males and 1941 females) were enrolled during an annual health check-up. Fatty liver was examined using a Philips HD 11 XE multi-function color Doppler diagnostic instrument, and baPWV was determined using a novel arteriosclerosis detection device. Blood pressure (BP), fasting plasma glucose (FPG), waist circumference (WC), plasma triglycerides (TG), high-density lipoprotein (HDL), total cholesterol (TC), low-density lipoprotein (LDL) and uric acid (UA) were measured using standard methods. The relationship between fatty liver with metabolic risk factors and baPWV was analyzed using regression analysis and the χ² test.

RESULTS: The values and abnormal rates of baPWV were significantly different between NAFLD patients and non-NAFLD subjects (P < 0.001). In addition, the values of baPWV were different by gender between NAFLD patients and non-NAFLD subjects. The OR values in females, males, and the entire population were 3.33, 1.67, and 2.13, respectively (P < 0.001). The incidence of high baPWV increased with increasing degree of NAFLD (levels 0, 1, 2, and 3) (P < 0.001), which was 45.9%, 54.5%, 60.2%, and 71.4% in males and 27.0%, 49.1%, 55.60%, and 60.0% in females (P < 0.001), respectively. Logistic regression analysis showed that the OR value for baPWV in the non-metabolic syndrome group and the metabolic syndrome group was 1.28 vs 1.14 (males) and 2.55 vs 0.98 (females). The OR values for baPWV in the non-high-BP and high-BP, non-high-WC and high-WC, non-high-FPG and high-FPG, non-high-TG and high-TG, non-high-HDL and high-HDL, non-high-TC and high-TC, non-high-LDL and high-LDL, non-high-UA and high-UA groups were 3.38 vs 1.19, 3.50 vs 1.44, 2.80 vs 2.30, 3.29 vs 1.88, 3.03 vs 3.28, 3.35 vs 2.70, 3.93 vs 1.66, and 3.20 vs 2.34, respectively, in females (P < 0.001), and were 1.37 vs 1.34, 1.56 vs 1.26, 1.51 vs 1.28, 1.49 vs 1.52, 1.71 vs 1.61, 1.59 vs 1.74, 1.76 vs 1.47, and 1.73 vs 1.54, respectively, in males (P < 0.01). The OR value for baPWV was still higher than 1.2 (1.21 in males and 1.40 in females) after adjustment for the metabolic component (0, 1, 2, 3, 4, 5, 6 and above) (P < 0.01).

CONCLUSION: NAFLD is closely correlated with baPWV, particularly in females. NAFLD has a large impact on baPWV, no matter whether the metabolic index is increased or not. NAFLD may be a useful indicator for assessing early arteriosclerosis.

A simple route to a 1D ferromagnetic Dy-containing compound showing magnetic relaxation behaviour

The relatively rare well-isolated 1D ferromagnetic chain of the Dy analogue displays magnetic relaxation behaviour.

Novel mutations m.3959G>A and m.3995A>G in mitochondrial gene MT-ND1 associated with MELAS

Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) are progressive neurodegenerative disorder associated with polygenetic, maternally inherited mutations in mitochondrial DNA. Approximately 80% of MELAS cases are caused by the mutation m.3243A>G of the mitochondrial tRNA(Leu (UUR)) gene (MT-TL1). We reported two probands with MELAS features. Muscle biopsy identified ragged-red fibers (RRF) in Gomori Trichrome staining. A respiratory chain function study showed decreased activity of mitochondrial respiratory chain complex I in both probands. Sequencing of the mitochondrial DNA revealed two novel MT-ND1 gene missense mutations, m.3959G>A and m.3995A>G, which are highly conserved among species. Protein secondary structure predictions demonstrated that these mutations may alter the peptide structure and may lead to decreased ND1 gene stability. Our findings suggest that these two novel mutations may contribute to the MELAS phenotypes of the patients in our study.

Evaluation of the Clinical Significance of Classification of Traumatic Anterior Shoulder Instability Using Double-Contrast Computed Tomography Arthrography

This study evaluated the clinical significance of traumatic anterior shoulder instability (TASI) classification using double-contrast computed tomography (CT) arthrography. Patient were randomly assigned to two groups: group 1 ( n = 62); and group 2 ( n = 63). TASI symptom severity in group 1 was assessed using physical signs of shoulder trauma and conventional X-ray, CT and magnetic resonance imaging; these patients received either conservative management (with physical rehabilitation) or standard surgery. Group 2 underwent double-contrast CT arthrography to classify TASI; its findings formed the basis of subsequent management. At 24 months post-therapy, significant improvements in clinical outcomes were observed in group 2: Constant scores were higher and Western Ontario Shoulder Instability Index scores were lower. At 24 months, recurrence rates were 21.0% (13/62) in group 1 and 7.9% (5/63) in group 2. Findings suggested that TASI classification using double-contrast CT arthrography provided meaningful information thereby improving treatment efficacy.

Clinical and pathological features in 15 Chinese patients with calpainopathy

BACKGROUND

Calpainopathy is comprised of a group of myopathies caused by deficiency in calcium-activated, neutral protease (calpain-3). In this study we identify calpainopathy in a cohort of Chinese patients with unclassified myopathy and analyze its clinical and pathological features.

METHODS

Sixty-six muscle biopsies were selected for combined Western blotting of dysferlin and calpain-3 after immunohistochemical staining. Clinical and pathological parameters of 15 confirmed calpainopathy cases were determined.

RESULTS

The diagnosis of calpainopathy in 15 Chinese patients was confirmed by Western blot analysis. Fourteen subjects had progressive proximal muscle weakness; 1 presented with bilateral distal muscle atrophy of the lower extremities. Scapular winging was observed in 12 patients (80%), and joint contractures were found in 10 others (66.7%). Histopathological studies showed a high prevalence of lobulated fibers (66.7%).

CONCLUSIONS

Chinese patients with calpainopathy share some common clinical and pathological features with the reported characteristics of non-Chinese patients.

Vascular regression and survival are differentially regulated by MT1-MMP and TIMPs in the aortic ring model of angiogenesis

This study was designed to investigate the role of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) in the reabsorption of neovessels in collagen gel cultures of rat and mouse aortic rings. Aortic angiogenesis was associated with collagen lysis and production of the matrix-degrading enzymes MMP-2, MMP-9, and membrane-type MMP (MT1-MMP, or MMP-14). Vascular growth and regression were not affected by disruption of MMP-2 or MMP-9. In addition, no effect on vascular regression was observed by blocking plasmin, a protease implicated in the activation of MMPs, with epsilon-aminocaproic acid or by adding plasminogen, which caused a modest increase in vascular proliferation. Conversely, angiogenesis was blocked and vessels stabilized by inhibiting MT1-MMP with neutralizing antibodies, TIMP-2, TIMP-3, or TIMP-4. TIMP-1, which blocks MMP-2 and MMP-9 but is a poor inhibitor of MT1-MMP, had no antiangiogenic effect. However, TIMP-1 prolonged the survival of neovessels following angiogenesis. Vascular regression was accelerated in aortic cultures from TIMP-1- and TIMP-2-deficient mice. The vascular survival effect of anti-MT1-MMP antibodies and TIMPs with MT1-MMP inhibitory activity was associated with complete inhibition of collagen lysis. In contrast, TIMP-1 had no anticollagenolytic effect. These results indicate that MT1-MMP plays a critical role not only in angiogenesis but also in vascular regression and demonstrate that TIMPs with anti-MT1-MMP activity have opposite effects on angiogenic outcomes depending on the stage of the angiogenic process. This study also suggests the existence of a TIMP-1-mediated alternate pathway of vascular survival that is unrelated to MT1-MMP inhibitory activity.

Evidence for programmed cell death and activation of specific caspase-like enzymes in the tomato fruit heat stress response

The tomato (Lycopersicon esculentum) fruit is the best available model to study the stress response of fleshy fruit. Programmed cell death (PCD) plays an important role in stress responses in mammals and plants. In this study, we provide evidence that PCD is triggered in the tomato fruit heat stress response by detection of the sequential diagnostic PCD events, including release of cytochrome c, activation of caspase-like proteases and the presence of TUNEL-positive nuclei. Investigating the time course of these events for 12 h after heat treatment indicated that cytochrome c release and caspase-like protease activation occurred rapidly and were consistent with the onset of DNA fragmentation. In addition, LEHDase and DEVDase enzymes were specifically activated in tomato fruit pericarp during the heat treatment and recovery time. There was no significant activation of YVADase or IETDase proteases. Preincubation of pericarp discs with the broad-spectrum, cell-permeable caspase inhibitor Z-VAD-FMK, suppressed heat-induced cell death measured by trypan blue, accompanied by a decrease in LEHDase and DEVDase activities.

The presence of GM-CSF and IL-4 interferes with effect of TGF-beta1 on antigen presenting cells in patients with multiple sclerosis and in rats with experimental autoimmune encephalomyelitis

The possibility to generate and expand tolerogenic dendritic cells (DC) with TGF-beta1 in vitro opens new therapeutic perspectives for the treatment of autoimmune diseases. In the present study, GM-CSF+IL-4 induced the differentiation of DC from adherent peripheral blood mononuclear cells, which had a higher expression of HLA-DR, CD86 and CD1a and the capacity to stimulate T cells. TGF-beta1 alone slightly promoted the generation of antigen presenting cells (APC) with higher expression of CD14, but did not differentiate them into E-cadherin+Langerhans cell (LC)-like DC. TGF-beta1-driven APC exhibited the morphology, phenotypes and functions of tolerogenic immature DC, and had lower capacity to stimulate T cells. In vivo experiment demonstrates that TGF-beta1-treated APC exhibited the therapeutic potential in Lewis rats with experimental autoimmune encephalomyelitis (EAE), followed by increase of IL-10 production in lymph nodes and decrease of inflammatory cells in spinal cords. Most importantly, GM-CSF/IL-4 used in DC preparation abolished the effect of TGF-beta1 to induce tolerogenic APC in vitro and in vivo. The results reveal that the usage of GM-CSF for the generation of tolerogenic DC should not be copied from DC preparation for anti-tumor therapy.

Two 3D Porous Lanthanide−Fumarate−Oxalate Frameworks Exhibiting Framework Dynamics and Luminescent Change upon Reversible De- and Rehydration

We present two porous luminescent compounds, [Ln2(fumarate)2(oxalate)(H2O)4].4H2O (Ln = Eu, Tb), prepared by the hydrothermal method. The materials have 3D framework structure consisting of oxalate pillared lanthanide-fumarate layers with intersected channels occupied by guest water. They exhibit framework dynamics upon several cycles of dehydration and rehydration. The crystallinity of the as-prepared hydrated materials degrades completely to the amorphous dehydrated phases, while it returns upon rehydration. A mechanism for de-/rehydration is proposed on the basis of the structure and spectroscopic data. The dehydration process is accompanied by the lost of luminescence of Ln ion, but the luminescence is recovered upon rehydration, where water molecules in fact enhance the luminescence but not quench it. This is probably due to the softened environment of lanthanide ion in the dehydrated amorphous phases and the recovery of the stiffness after rehydration.

The limitation of IL-10-exposed dendritic cells in the treatment of experimental autoimmune myasthenia gravis and myasthenia gravis

Dendritic cells (DC) are highly specialized antigen presenting cells that play critical roles as instigators and regulators of immune responses including B cell function, antibody synthesis and isotype switch. In this study, we compared immunotherapeutic effect of IL-10-treated DC (IL-10-DC) via both intraperitoneal (i.p.) and subcutaneous (s.c.) delivery in rats with incipient experimental autoimmune myasthenia gravis (EAMG). Spleen DC were isolated from onset of EAMG on day 39 post-immunization, exposed in vitro to IL-10, and then injected into incipient EAMG at dose of 1 x 10(6) cells/rat on day 5 after immunization. Intraperitoneal administration of IL-10-DC suppressed clinical scores, anti-acetylcholine receptors (AChR) antibody secreting cells, antigen-specific IL-10/IFN-gamma production and T cell proliferation compared to control EAMG rats. Importantly, IL-10-DC, if given by s.c. route, failed to ameliorate clinical sign of EAMG. Simultaneously, T cell proliferation, anti-AChR antibody secreting cells and IL-10/IFN-gamma production had no alteration, as compared to control EAMG rats. Both in vitro and in vivo experiments showed that treatment of IL-10 inhibited the migration of DC toward MIP-3beta and lymph node, indicating that in vitro manipulation of DC with IL-10 alters the migration of DC that influences the therapeutic effect in the treatment of autoimmune diseases. In MG patients, neither the improvement of clinical symptom nor the alteration of immunological parameter was observed through s.c. delivery of IL-10-DC, suggesting the limitation of IL-10-DC in the treatment of MG patients.

A 3D porous lanthanide–fumarate framework with water hexamer occupied cavities, exhibiting a reversible dehydration and rehydration procedure

[Sm2(fumarate)3(H2O)4] x 3 H2O, a new porous pillared layer framework with 0D cavities for the accommodation of chair-like hexameric water clusters, possesses three kinds of fumarate ligand with their two COO ends adopting different coordination modes and shows reversible de- and re-hydration behavior.

Use of vascular explants for ex vivo neovascularization of biomaterials

Biomaterial polymers have been proposed as scaffolds for cell assembly in vascular bioengineering. We describe here a new method for the neovascularization of polyurethane meshes from explants of rat aorta. Aortic rings embedded in collagen-permeated polyurethane meshes and cultured in medium supplemented with fetal bovine serum and vascular endothelial growth factor generated florid microvascular outgrowths that efficiently vascularized the available spaces between polyurethane fibers. The neovessels could be identified in the live cultures by phase-contrast microscopy, and in formalin-fixed preparations by the ABC peroxidase procedure, using the endothelial-specific Griffonia isolectin B4. The aortic outgrowths were successfully labeled with the intravital fluorescent dyes Calcein AM or SPDiOC(18), which are nontoxic and can be used for tracking studies. This study shows that artificial biomaterial meshes can be colonized ex vivo with histotypic microvascular networks, and provides the proof of concept for the future development of stably vascularized devices for in vivo implantation.

Production and characterization of a Tie2 agonist monoclonal antibody

The Tie2 receptor and its known ligands, the angiopoietins, play a critical role in endothelial cell differentiation during the process of angiogenesis. Recent experimental observations indicate that the agonistic ligand, angiopoietin-1, can stimulate endothelial cell sprouting and act as a chemo-attractant in vitro and induce increased and enhanced angiogenesis both alone and in conjunction with vascular endothelial growth factor (VEGF) in vivo. Here, we present a monoclonal antibody (MAb), which binds to the extracellular portion of the Tie2 receptor and elicits similar agonist effects. Upon MAb binding to the native Tie2 receptor of cultured human umblical vein endothelial cells (HUVEC), there is a rapid increase in receptor autophosphorylation with a concomitant enhancement in the recruitment and association of the signalling intermediates Grb2 and SH-PTP2. The antibody further demonstrates functional activity in vascular tissues. In vitro, the antibody promotes the survival of cultured HUVEC and elicits a dose dependent outgrowth and branching of microvessels from cultured explants of rat aorta. When administered in vivo, the antibody enhances the vascularization of subcutaneous Matrigel implants in mice. Together these data suggest that the antibody is capable of acting as a surrogate ligand for Tie2 and further confirms the role of Tie2 in the differentiation of endothelial cells during angiogenesis.

Effects of stress factors, bioregulators, and synthetic precursors on indole alkaloid production in compact callus clusters cultures of Catharanthus roseus

Compact callus cluster (CCC) cultures established from Catharanthus roseus consist of cohesive callus aggregates displaying certain levels of cellular or tissue differentiation. CCC cultures synthesize about two-fold more indole alkaloids than normal dispersed-cell cultures. Our studies here show that additions of KCl, mannitol, and a variety of synthetic precursors and bioregulators to the CCC cultures markedly improved indole alkaloid production and release of these alkaloids into the medium. Treatment with 250 mM mannitol and 4 g/l KCl yielded 42.3 mg l(-1) and 33.6 mg l(-1)of ajmalicine, respectively; these amounts were about four-fold higher than the control. Succinic acid, tryptamine, and tryptophan feedings also significantly increased ajmalicine (41.5 mg l(-1), 36.9 mg l(-1), and 31.8 mg l(-1), respectively) and catharanthine (21.1 mg l(-1), 17.2 mg l(-1), and 18 mg l(-1), respectively) production by the CCC cultures, while geraniol feeding inhibited biomass and alkaloid accumulation. We also found that tetramethyl ammonium bromide could significantly improve ajmalicine production (49.3 mg l(-1)) and catharanthine production (18.3 mg l(-1)) in C. roseus CCC cultures. The mechanisms responsible for these treatment effects are discussed herein.

[Studies on single cell cloning of Ginkgo biloba L]

OBJECTIVE

To investigate the relations of the productivity stability of to the homogenization of Ginkgo biloba cells by single cell clones.

METHOD

Using plant single cell plate culture technique.

RESULTS

Adding 500 ml.L-1L-glutamine in the medium increased greatly the cell plating efficiency (PE), and within the range 0.5-5.0 x 10(4) Cell.ml-1 of the initial cell density, the PE increased with the increment of the cell density. Of the 48 cell clones obtained, the GKB content in G-22 clone reached 0.099%; and most of the clones remain stable in growth and GKB production during subcultures.

CONCLUSION

During the cell and tissue culture of G. biloba, the application of plant single cell cloning technique helps to a certain extent solve the problem of productivity instability of ginkgolide.

[Effects of culture conditions on callus growth and taxol formation of Taxus yunnanensis Cheng et L.K.Fu]

OBJECTIVE

To seek culture conditions suitable for the callus growth and taxol formation of Taxus yunnanensis.

METHOD

Determining the growth index and taxol content in the callus cultured under different illumination conditions or on different media.

RESULTS AND CONCLUSION

Darkness, the combination of 0.1 mg.L-1BAP and 2,4-D 1.0 mg.L-1, and B5, DCR or 6,7-V basal medium were favorable for the callus growth and taxol formation of Taxus yunnanensis; high NO3- concentration in the medium promoted callus growth, and high NH4+ concentration greatly inhibited callus growth, but dramatically increased taxol content.

Regulation of vascular growth and regression by matrix metalloproteinases in the rat aorta model of angiogenesis

Matrix metalloproteinases (MMPs) have been implicated in the formation of microvessels during angiogenesis, but their role in vascular regression is poorly understood. The rat aorta model of angiogenesis was used to study the function of MMPs at different stages of the angiogenic process. Gelatin zymography and Western analysis demonstrated production of MMP-2 and MMP-9 by aortic outgrowths in serum-free collagen gel culture. MMP-2 was found in both culture medium and collagen gel, whereas MMP-9 was predominantly associated with the gel. MMP expression increased gradually during the angiogenic growth phase and stayed high when vessels regressed and collagen lysed around the aortic rings. The MMP inhibitors, batimastat and marimastat, blocked formation of microvessels when added to the culture medium at the beginning of the experiment. They, however, stabilized the microvessels and prevented vascular regression after the angiogenic growth phase. This effect was observed also under conditions of angiogenic stimulation by basic fibroblast growth factor. MMP inhibitor-mediated stabilization of microvessels was associated with inhibition of collagen lysis and accumulation of collagen fibrils in the subendothelial space. This study demonstrates that MMPs promote microvessel formation during the early stages of angiogenesis, but also contribute to the reabsorption of the neovasculature in the later stages of this process. The time-dependent divergent effects of MMPs on microvessel growth and survival may influence the in vivo activity of MMP inhibitors used to treat angiogenesis-dependent disorders.

Role of the D2 dopamine receptor in molecular adaptation to chronic hypoxia in PC12 cells

We have previously shown that pheochromocytoma (PC12) cells rapidly depolarize and undergo Ca2+ influx through voltage-dependent Ca2+ channels in response to moderate hypoxia and that intracellular free Ca2+ is modulated by activation of dopamine D2 receptors in this cell type. The present study shows that D2 (quinpirole-mediated) inhibition of a voltage-dependent Ca2+ current (ICa) in PC12 cells is dramatically attenuated after chronic exposure to moderate hypoxia (24 h at 10% O2). Pretreatment of cells with pertussis toxin abolished D2-mediated inhibition of ICa. The D2-induced inhibition of ICa did not depend on protein kinase A (PKA), as it persisted both in the presence of a specific PKA inhibitor (PKI) and in PKA-deficient PC12 cells. Prolonged exposure to hypoxia (24 h) significantly reduced the level of Gi/o alpha immunoreactivity, but did not alter G beta levels. Furthermore, dialysis of recombinant G(o) alpha protein through the patch pipette restored the inhibitory effect of quinpirole in cells chronically exposed to hypoxia. We conclude that the attenuation of the D2-mediated inhibition of ICa by chronic hypoxia is caused by impaired receptor-G protein coupling, due to reduced levels of G(o) alpha protein. This attenuated feedback modulation of ICa by dopamine may allow for a more sustained Ca2+ influx and enhanced cellular excitation during prolonged hypoxia.

Cyclic AMP-specific phosphodiesterase inhibitor rolipram and RO-20-1724 promoted apoptosis in HL60 promyelocytic leukemic cells via cyclic AMP-independent mechanism

Phosphodiesterases (PDEs) are responsible for the hydrolysis of cAMP and cGMP which act as intracellular second messengers in a variety of cellular functions. In this paper we report that PDE3 and PDE4 were two dominant classes of PDEs expressed in HL60 cells. The influence of specific PDE inhibitors on apoptosis in HL60 cells was studied. The non-specific inhibitor IBMX and PDE3 specific inhibitors (milrinone and trequinsin) did not promote apoptosis. They inhibited apoptosis induced by paclitaxel or thapsigargin. However, PDE4 specific inhibitors (rolipram and RO-20-1724) promoted apoptosis within 5 h. In HL60 cells, other cAMP-eliciting reagents (8-bromo-cAMP, Sp-cAMP and forskolin) also inhibited apoptosis, while cell-permeable cGMP analogs did not affect apoptosis. Therefore, IBMX and PDE3 specific inhibitors may prevent HL60 cells from apoptosis by increasing intracellular cAMP. However, apoptosis induced by PDE4 specific inhibitors is not likely due to increased cAMP level. These results suggest that rolipram and RO-20-1724 promoted apoptosis in HL60 cells through cAMP-independent mechanism.

Expression of dopamine D2 receptor in PC-12 cells and regulation of membrane conductances by dopamine

PC-12 cells depolarize during hypoxia and release dopamine. The hypoxia-induced depolarization is due to inhibition of an O2-sensitive K+ current. The role of dopamine released during hypoxia is uncertain, but it could act as an autocrine to modulate membrane conductance during hypoxia. The current study was undertaken to investigate this possibility. Reverse transcription-polymerase chain reaction and sequence analysis revealed that the D2 isoform of the dopamine receptor is expressed in rat PC-12 cells. Exogenously applied dopamine and the D2 agonist quinpirole elicited inhibition of a voltage-dependent K+ current (I(K)) that was prevented by sulpiride, a D2 receptor antagonist. Dopamine and quinpirole applied during hypoxia potentiated the inhibitory effect of hypoxia on I(K). We also found that quinpirole caused reversible inhibition of a voltage-dependent Ca2+ current (I(Ca)) and attenuation of the increase in intracellular free Ca2+ during hypoxia. Our results indicate that dopamine released from PC-12 cells during hypoxia acts via a D2 receptor to "autoregulate" I(K) and I(Ca).

Membrane depolarization in PC-12 cells during hypoxia is regulated by an O2-sensitive K+ current

The effects of hypoxia on K+ current (IK), resting membrane potential, and cytosolic free Ca2+ in rat pheochromocytoma (PC-12) cells were studied. Whole cell voltage- and current-clamp experiments were performed to measure IK and membrane potential, respectively. Cytosolic free Ca2+ level was measured using the Ca(2+)-sensitive fluorescent dye fura 2. Depolarizing voltage steps to +50 mV from a holding potential of -90 mV elicited a slowly inactivating, tetraethylammonium chloride-sensitive, and Ca(2+)-insensitive IK that was reversibly inhibited by reduced O2 tension. Graded reduction in PO2 (from 150 to 0 mmHg) induced a graded inhibition of O2-sensitive IK [IK(O2)] up to 46% at 0 mmHg. Moreover, hypoxia induced a 19-mV membrane depolarization and a twofold increase in cytosolic free Ca2+. In Ca(2+)-free condition, inhibition of IK(O2) induced an 8-mV depolarization, suggesting that inhibition of IK(O2) was responsible for initiating depolarization. The effect of reduced PO2 on the current-voltage relationship showed a reduction of outward current and a 14-mV shift in the reversal potential comparable with the amount of depolarization measured in current clamp experiments. Neither Ca(2+)-activated IK nor inwardly rectifying IK are responsible for the hypoxia-induced depolarization. In conclusion, PC-12 cells express an IK(O2), inhibition of which leads to membrane depolarization and increased intracellular Ca2+, making the PC-12 clonal cell line a useful model for studying the molecular and biophysical mechanisms that mediate O2 chemosensitivity.

Differential effects of phorbol ester on apoptosis in HL-60 promyelocytic leukemia cells

The role of the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) in apoptosis of HL-60 cells was investigated. PMA inhibited DNA fragmentation induced by thapsigargin (TG) and 4-bromo-calcium ionophore (Br-A23187). The inhibitory effect of PMA was concentration-related and was abolished by a specific PKC inhibitor, bisindolylmaleimide (GF109203X. In addition TG-induced apoptosis was decreased in cells in which PKC activity was down-regulated by long-term pretreatment with PMA. These results indicate that PKC activation by PMA inhibits HL-60 cell apoptosis induced by TG and Br-A23187, and that this inhibition is not influenced by the down-regulation of PKC. However, PMA did not inhibit DNA fragmentation induced by 1-beta-D-arabinofuranosylcytosine (Ara-C) and cycloheximide. PMA suppressed TG- or Br-A23187. Our results indicate that PKC participates in the regulation of apoptosis only by some pathways. Down-regulation of PKC is not responsible for the diverse effects of PKC activators on apoptosis. The effect of a PKC modulator on apoptosis is dependent upon interaction with individual apoptotic stimulus.

Effects of Na+/H+ antiport and intracellular pH in the regulation of HL-60 cell apoptosis

The roles of Na+/H+ antiport and intracellular pH in apoptosis of HL-60 cells were investigated here. We found that dimethyl amiloride, a specific Na+/H+ antiport inhibitor, induced intracellular acidification but not apoptosis; while sodium ionophore, monensin caused intracellular alkalinization as well as apoptosis in HL-60 cells. Br-A23187 and thapsigargin could induce a various degree of intracellular alkalinization through the stimulation of Na+/H+ antiport. Dimethyl amiloride blocked the intracellular alkalinization and inhibited apoptosis induced by Br-A23187 and thapsigargin. PMA also stimulated Na+/H+ antiport and induced intracellular alkalinization which was completely blocked by dimethyl amiloride and partially attenuated by PKC inhibitors. PMA could inhibit apoptosis in HL-60 cells. PMA-induced suppression of apoptosis was, however, not interfered by dimethyl amiloride, but could be abolished by PKC inhibitors. These results indicate that pHi alkalinization and/or the stimulation of Na+/H+ antiport, instead of intracellular acidification, are contributory to the induction of apoptosis. PMA-induced inhibition of apoptosis is not necessarily associated with intracellular alkalinization, but primarily due to activation of PKC. We suggest that stimulation of Na+/H+ antiport and pHi alkalinization act as facilitating factors in the induction of apoptosis.

Roles of calcium in the regulation of apoptosis in HL-60 promyelocytic leukemia cells

Increase in intracellular calcium concentrations ([Ca2+]i) is critical for the initiation of apoptosis in cells such as thymocytes and in other cells, calcium chelators may promote apoptosis. However, calcium modulators, such as calcium ionophore 4-bromo-calcium ionophore (Br-A23187) and thapsigargin (TG), induce apoptosis in different cells, including HL-60 cells in which the induction of apoptosis seems a calcium-independent process. These observations imply that the disturbance of calcium homeostasis is probably the most important factor in the regulation of apoptosis. In this article, reagents with different potencies of modulating calcium homeostasis were used to study the possible role of [Ca2+]i and the status of intracellular calcium stores in the causation of HL-60 cell apoptosis. We found that an increase in [Ca2+]i alone did not result in apoptosis, while the depletion of TG-sensitive calcium stores in the endoplasmic reticulum was closely related with the induction of apoptosis. In HL-60 cells, extracellular and intracellular calcium chelators promoted apoptosis. Calmodulin antagonist did not attenuate apoptosis induced by other reagents. Our results suggest that the depletion of Ca2+ stores is an important mean to modulate calcium homeostasis and that the mobilization of calcium (Ca2+) from intracellular stores, rather than an increase in [Ca2+]i, provides the signal for the induction of apoptosis in HL-60 cells.