Higher-order combinatorial chromatin perturbations by engineered CRISPR-Cas12a for functional genomics

Multiplexed genetic perturbations are critical for testing functional interactions among coding or non-coding genetic elements. Compared to double-stranded DNA cutting, repressive chromatin formation using CRISPR interference (CRISPRi) avoids genotoxicity and is more effective for perturbing non-coding regulatory elements in pooled assays. However, current CRISPRi pooled screening approaches are limited to targeting 1-3 genomic sites per cell. To develop a tool for higher-order ( > 3) combinatorial targeting of genomic sites with CRISPRi in functional genomics screens, we engineered an Acidaminococcus Cas12a variant -- referred to as mul tiplexed transcriptional interference AsCas12a (multiAsCas12a). multiAsCas12a incorporates a key mutation, R1226A, motivated by the hypothesis of nicking-induced stabilization of the ribonucleoprotein:DNA complex for improving CRISPRi activity. multiAsCas12a significantly outperforms prior state-of-the-art Cas12a variants in combinatorial CRISPRi targeting using high-order multiplexed arrays of lentivirally transduced CRISPR RNAs (crRNA), including in high-throughput pooled screens using 6-plex crRNA array libraries. Using multiAsCas12a CRISPRi, we discover new enhancer elements and dissect the combinatorial function of cis-regulatory elements. These results instantiate a group testing framework for efficiently surveying potentially numerous combinations of chromatin perturbations for biological discovery and engineering.

X-ray and neutron scattering measurements of ordering in a Cu46Zr54 liquid

The structural evolution of the equilibrium and supercooled Cu₄₆Zr₅₄ liquids was investigated with a combination of elastic neutron scattering (with isotopic substitution) and synchrotron x-ray scattering studies. The partial pair correlation functions were determined over a wide temperature range (∼270 °C). These show that the Cu-Cu and Zr-Zr ordering increases as the temperature decreases, while the Cu-Zr ordering decreases. This surprising result is in contradiction with the results from molecular dynamics studies.

Differentially expressed proteins identified by TMT proteomics analysis in bone marrow microenvironment of osteoporotic patients

We applied tandem mass tag (TMT)-based proteomics to investigate protein changes in bone marrow microenvironment of osteoporotic patients undergoing spine fusion. Multiple bioinformatics tools were used to identify and analyze 219 differentially expressed proteins. These proteins may be associated with the pathogenesis of osteoporosis.

INTRODUCTION

Bone marrow microenvironment is indispensable for the maintenance of bone homeostasis. We speculated that alterations of some factors in the microenvironment of osteoporotic subjects might influence the homeostasis. This study aimed to investigate the changes in the expression of protein factors in the bone marrow environment of osteoporosis.

METHODS

We performed a proteomics analysis in the vertebral body-derived bone marrow supernatant fluid from 8 Chinese patients undergoing posterior lumbar interbody fusion (4 osteoporotic vs. 4 non-osteoporotic) and used micro-CT to analyze the microstructural features of spinous processes from these patients. We further performed western blotting to validate the differential expressions of some proteins.

RESULTS

There was deteriorated bone microstructure in osteoporotic patients. Based on proteomics analysis, 172 upregulated and 47 downregulated proteins were identified. These proteins had multiple biological functions associated with osteoblast differentiation, lipid metabolism, and cell migration, and formed a complex protein-protein interaction network. We identified five major regulatory mechanisms, splicing, translation, protein degradation, cytoskeletal organization, and lipid metabolism, involved in the pathogenesis of osteoporosis.

CONCLUSIONS

There are various protein factors, such as DDX5, PSMC2, CSNK1A1, PLIN1, ILK, and TPM4, differentially expressed in the bone marrow microenvironment of osteoporotic patients, providing new ideas for finding therapeutic targets for osteoporosis.

A possible structural signature of the onset of cooperativity in metallic liquids

It is widely, although not universally, believed that there must be a connection between liquid dynamics and the structure. Previous supporting studies, for example, have demonstrated a link between the structural evolution in the liquid and kinetic fragility. Here, new results are presented that strengthen the evidence for a connection. By combining the results from high-energy synchrotron X-ray scattering studies of containerlessly processed supercooled liquids with viscosity measurements, an accelerated rate of structural ordering beyond the nearest neighbors in the liquid is demonstrated to correlate with the temperature at which the viscosity transitions from Arrhenius to super-Arrhenius behavior. This is the first confirmation of predictions from several recent molecular dynamics studies.

Comparison of effectiveness and safety between conbercept and ranibizumab for treatment of neovascular age-related macular degeneration. A retrospective case-controlled non-inferiority multiple center study

Purpose

To compare the efficacy and safety of conbercept and ranibizumab when administered according to a treat-and-extend (TREX) protocol for the treatment of neovascular age-related macular degeneration (AMD) in China.

Patients and methods

Between May 2014 and May 2015, 180 patients were treated in a 1 : 1 ratio using conbercept or ranibizumab from four hospitals. Patients received either conbercept 0.5 mg or ranibizumab 0.5 mg intravitreal injections. Follow-up time was 1 year and treated based on a TREX approach. Main outcomes and measures include best-corrected visual acuity (BCVA), using Early Treatment Diabetic Retinopathy Study (ETDRS); number of injections; central retinal thickness (CRT); and leakage of choroidal neovascularization before and after the treatment was analyzed by fluorescein fundus angiography and indocyanine green angiography.

Results

The 1-year visit was completed by 168 (93.3%) of patients. Mean BCVA was equivalent between two cohorts, and were improved by 12.7±7.770 and 12.3±7.269 letters in the conbercept and ranibizumab cohorts, respectively (P=0.624). There was no significant difference in measured CRT, with a mean decrease of 191.5 μm for conbercept and 187.8 μm for ranibizumab (P=0.773). There was a statistically significant difference (P=0.001) between the drugs regarding the number of treatments: 7.4 for conbercept and 8.7 for ranibizumab. The difference in the distribution of injection intervals was statistically significant between two groups (P=0.011). During the study, there were no cases of endophthalmitis or intraocular inflammation.

Conclusion

Both drugs had equivalent effects in visual and anatomic gains at 1 year when administered. In the conbercept group, longer treatment intervals were achieved with more patients.

Comparison of two series of non-invasive instruments used for the skin physiological properties measurements: the DermaLab® from Cortex Technology vs. the series of detectors from Courage & Khazaka

BACKGROUND/PURPOSE

The detectors from Courage & Khazaka and DermaLab^® from Cortex Technology were two series of the most commonly used non-invasive instruments for the skin physiological properties measurements. The aim of this study is to reveal the differences and correlations in measuring skin color, hydration, transepidermal water loss (TEWL), sebum and elasticity on the forearm or faces between two commercially available series of instruments.

METHODS

30 subjects were enrolled to be measured by the two series of instruments. The measurements by each series were performed on the left/right side of the body randomly. The hydration, sebum, elasticity and TEWL measurements were performed on different sites.

RESULTS

Positive correlations were found in the values of skin color, hydration, TEWL, sebum and visco-elasticity detected by the two series. The values related to skin firmness measured by the two instruments were statistically negative correlated. Contrary to the results in measuring the skin color, the detectors from Courage & Khazaka presented lower values of variation in measuring skin hydration and TEWL than those from DermaLab^® .

CONCLUSION

The two series have significant correlations.The differences of the two series can be due either to differences in the design of the probe or left/right part of the body.

Gankyrin drives malignant transformation of chronic liver damage-mediated fibrosis via the Rac1/JNK pathway

Hepatocarcinogenesis is a complex process involving chronic liver injury, inflammation, unregulated wound healing, subsequent fibrosis and carcinogenesis. To decipher the molecular mechanism underlying transition from chronic liver injury to dysplasia, we investigated the oncogenic role of gankyrin (PSMD10 or p28^GANK) during malignant transformation in a transgenic mouse model. Here, we find that gankyrin increased in patients with cirrhosis. In addition to more severe liver fibrosis and tumorigenesis after DEN plus CCl₄ treatment, hepatocyte-specific gankyrin-overexpressing mice (gankyrin^hep) exhibited malignant transformation from liver fibrosis to tumors even under single CCl₄ administration, whereas wild-type mice merely experienced fibrosis. Consistently, enhanced hepatic injury, severe inflammation and strengthened compensatory proliferation occurred in gankyrin^hep mice during CCl₄ performance. This correlated with augmented expressions of cell cycle-related genes and abnormal activation of Rac1/c-jun N-terminal kinase (JNK). Pharmacological inhibition of the Rac1/JNK pathway attenuated hepatic fibrosis and prevented CCl₄-induced carcinogenesis in gankyrin^hep mice. Together, these findings suggest that gankyrin promotes liver fibrosis/cirrhosis progression into hepatocarcinoma relying on a persistent liver injury and inflammatory microenvironment. Blockade of Rac1/JNK activation impeded gankyrin-mediated hepatocytic malignant transformation, indicating the combined inhibition of gankyrin and Rac1/JNK as a potential prevention mechanism for cirrhosis transition.

Relationship between psychosocial factors and onset of multiple sclerosis

OBJECTIVE

The aim of this study was to investigate the influence of psychosocial variables on patients with multiple sclerosis (MS) and the relationship between these variables and the onset of MS.

BACKGROUND

The current evidence indicates that many types of psychosocial factors are involved in the development and relapse of MS, and it has been suggested that they could serve as predictors as well. So far, little has been reported on the effect of psychosocial factors on MS and the relationship between psychosocial factors and the onset of MS.

METHODS

Forty-one patients, 15 males and 26 females, average age 37.44 +/- 12.24 years (mean +/- SD), were evaluated by the Life Event Scale, Eysenck Personality Questionnaire, Social Support Revaluate Scale and Symptom Check List 90 and compared with 41 equivalent healthy control subjects, 15 males and 26 females, average age 36.38 +/- 12.84 years (mean +/- SD). Disease, demographic, psychosocial and lifestyle factors were measured at baseline. Patients with MS were first diagnosed by 3 neurologists according to the Poser (1983) MS diagnostic criteria.

RESULTS

Significant differences were found between the MS and the control group in their negative emotions and symptoms such as depression, anxiety, obsession, phobia, tense interpersonal relationship and somatization disorder. Significant differences were found between the two groups in the total number of negative life events, their family problems and the utilization of social support. The scores for various negative emotions in the MS group correlated positively with those for neuroticisms in personality type, and negatively with those for introverted and extroverted personality. Many kinds of negative emotions in the MS group correlated positively with the total number of life events, negative life events and family problems. Many kinds of negative emotions in the MS group correlated negatively with the utilization of social support.

CONCLUSION

The psychosocial factors are closely associated with MS onset and may play important roles in the development of the disease.

New metabolites of fenofibrate in Sprague-Dawley rats by UPLC-ESI-QTOF-MS-based metabolomics coupled with LC-MS/MS

Fenofibrate has been widely used for the treatment of dyslipidaemia with a long history. Species differences of its metabolism were reported, but its metabolites in rodent have not been fully investigated. Urine and plasma samples were collected before and after oral dosages of fenofibrate in Sprague-Dawley rats. Urine samples were subjected to ultra-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS) analysis, and projection to latent structures discriminant analysis was used for the identification of metabolites. New metabolites in urine and plasma were also studied by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The metabolism pathway was studied in rat hepatocytes. Synthesized and purchased authentic compounds were used for metabolite identification by LC-MS/MS. Five ever-reported metabolites were identified and another four new ones were found. Among these new metabolites, fenofibric acid taurine and reduced fenofibric acid taurine indicate new phase II conjugation pathway of fenofibrate.

On the thermal elevation of a 60-electrode epiretinal prosthesis for the blind

In this paper, the thermal elevation in the human body due to the operation of a dual-unit epiretinal prosthesis to restore partial vision to the blind affected by irreversible retinal degeneration is presented. An accurate computational model of a 60-electrode device dissipating 97 mW power, currently under clinical trials is developed and positioned in a 0.25 mm resolution, heterogeneous model of the human head to resemble actual conditions of operation of the prosthesis. A novel simple finite difference scheme combining the explicit and the alternating-direction implicit (ADI) method has been developed and validated with existing methods. Simulation speed improvement up to 11 times was obtained for the the head model considered in this work with very good accuracy. Using this method, solutions of the bioheat equation were obtained for different placements of the implant. Comparison with in-vivo experimental measurements showed good agreement.

Disease-associated fibronectin matrix fragments trigger anoikis of human primary ligament cells: p53 and c-myc are suppressed

Inflammation in periodontal disease is characterized by the breakdown of the extracellular matrix. This study shows that an inflammation-associated matrix breakdown fragment of fibronectin (FN) induces anoikis of human periodontal ligament (PDL) cells. This 40 kDa fragment was identified in human inflammatory crevicular fluid and is associated with disease status. Previously, we reported that a similar recombinant FN fragment triggered apoptosis of PDL cells by an alternate apoptotic signaling pathway that requires transcriptional downregulation of p53 and c-myc. Thus, to determine whether the physiologically relevant 40 kDa fragment triggers apoptosis in these cells, the 40 kDa fragment was generated and studied for its apoptotic properties. The 40 kDa fragment induces apoptosis of PDL cells, and preincubation of cells with intact vitronectin, FN, and to a limited extent collagen I, rescue this apoptotic phenotype. These data suggest that the 40 kDa fragment prevents PDL cell spreading, thereby inducing anoikis. The signaling pathway also involves a downregulation in p53 and c-myc, as determined by Western blotting and real time quantitative PCR. These data indicate that an altered FN matrix as is elaborated in inflammation induces anoikis of resident cells and thus may contribute to disease progression.

Heat shock factor-4 (HSF-4a) is a repressor of HSF-1 mediated transcription

Heat shock transcription factors (HSFs) regulate the expression of heat shock proteins and other molecular chaperones that are involved in cellular processes from higher order assembly to protein degradation and apoptosis. Among the human HSFs, HSF-4 is expressed as at least two splice variants. One isoform (HSF-4b) possesses a transcriptional activation domain, but this region is absent in the other isoform (HSF-4a). We have recently shown that the HSF-4a isoform represses basal transcription from heterologous promoters both in vitro and in vivo. Here we show that HSF-4a and HSF-4b have dramatically different effects on HSF-1-containing nuclear bodies, which form after heat shock. While the expression of HSF-4b colocalizes with nuclear granules, the expression of HSF-4a prevents their formation. In addition, there is a concurrent reduction of HSF-1 in the nucleus, and there is reduction in its DNA binding activity and in HSE-dependent transcription of a reporter gene. To better understand the mechanism by which HSF-4a represses transcription, we inducibly expressed HSF-4a in cells and found that HSF-4a binds to the heat shock element (HSE) during attenuation of the heat shock response. Thus HSF-4a is an active repressor of HSF-1-mediated transcription. This repressor function makes the HSF-4a isoform unique within the HSF family.

Medial axis reformation: a new visualization method for CT angiography

RATIONALE AND OBJECTIVES

The authors performed this study to evaluate a new method (medial axis reformation [MAR]) for visualizing three-dimensional vascular data at electron-beam computed tomographic (CT) angiography.

MATERIALS AND METHODS

MAR was performed automatically with a personal computer-based workstation. After the region of interest was edited, voxels were divided into groups according to their path lengths. Centroids of groups were connected to form the medial axis. Then, the medial axis was refined with multiscale medial response. Bifurcations were also detected and refined. Finally, curved sections were generated through the branches and laid out onto a single image by using a splitting method. The authors performed MAR during electron-beam CT angiography of coronary arteries, common carotid arteries, and iliac arteries.

RESULTS

MAR displayed curved sections of branched vessels on one image, cut through the axis of vessels to show the vessel diameter objectively, and allowed the viewing direction to be altered arbitrarily.

CONCLUSION

Results of preliminary applications demonstrate that MAR is a valuable new visualization method for CT angiography.

Identification of protein carbonyls after two-dimensional electrophoresis

The oxidative modification of proteins plays a major role in a number of human diseases, but identity of the specific proteins that are most susceptible to oxidation has posed a difficult problem. Protein carbonyls are increased after oxidative stress, and after derivatization with 2,4-dinitrophenyl hydrazine (DNP) they can be detected by various analytical and immunological methods. Although high resolution two-dimensional electrophoresis (2-DE) can resolve virtually all proteins present in a cell or tissue it has been difficult to determine the oxidized proteins because the DNP-derivatization process alters the isoelectric points of proteins, and additional procedures must be utilized to remove reaction byproducts. These additional procedures can lead to loss of sample, and poor isoelectric resolution on immobilized pH gradient (IPG) strips. We have developed a method that allows the IPG strips to be derivatized with DNP directly following isoelectric focusing of the proteins. This method allows the visualization of oxidized proteins by 2-DE with high reproducibility.

Heat shock factor-4 (HSF-4a) represses basal transcription through interaction with TFIIF

The heat shock transcription factors (HSFs) regulate the expression of heat shock proteins (hsps), which are critical for normal cellular proliferation and differentiation. One of the HSFs, HSF-4, contains two alternative splice variants, one of which possesses transcriptional repressor properties in vivo. This repressor isoform inhibits basal transcription of hsps 27 and 90 in tissue culture cells. The molecular mechanisms of HSF-4a isoform-mediated transcriptional repression is unknown. Here, we present evidence that HSF-4a inhibits basal transcription in vivo when it is artificially targeted to basal promoters via the DNA-binding domain of the yeast transcription factor, GAL4. By using a highly purified, reconstituted in vitro transcription system, we show that HSF-4a represses basal transcription at an early step during preinitiation complex assembly, as pre-assembled preinitiation complexes are refractory to the inhibitory effect on transcription. This repression occurs by the HSF-4a isoform, but not by the HSF-4b isoform, which we show is capable of activating transcription from a heat shock element-driven promoter in vitro. The repression of basal transcription by HSF-4a occurs through interaction with the basal transcription factor TFIIF. TFIIF interacts with a segment of HSF-4a that is required for the trimerization of HSF-4a, and deletion of this segment no longer inhibits basal transcription. These studies suggest that HSF-4a inhibits basal transcription both in vivo and in vitro. Furthermore, this is the first report identifying an interaction between a transcriptional repressor with the basal transcription factor TFIIF.

Evaluation of coronary artery bypass graft patency using three-dimensional reconstruction and flow study of electron beam tomography

OBJECTIVE

To establish and evaluate two protocols for the noninvasive visualization and assessment of coronary artery bypass graft (CABG) patency on electron beam tomography (EBT).

METHODS

Two hundred and fourteen consecutive patients who underwent coronary artery bypass graft surgery were scanned using both EBT angiography with 3-dimensional reconstruction and EBT flow study with time-density-curve analysis.

RESULTS

There were 589 CABGs evaluated in this study (10 grafts were excluded because of artifacts). Among them, 133 (98.5%) of 135 arterial grafts were patent, and 345 (77.7%) of 444 saphenous-vein grafts were patent. Within 5 years or between 5 and 10 years after operation, arterial graft patency exceeded venous graft patency (P < 0.001). Three-dimensional EBT angiography achieved higher sensitivity, specificity and accuracy (97.7%, 94.1% and 96.7%, respectively) than did EBT flow study (88.4%, 82.4% and 85.2%, respectively) for evaluating occlusion or patency of CABG. The intra-graft flow of patent arterial and venous grafts were 4.9 +/- 2.2 ml.min-1.g-1 and 6.9 +/- 2.8 ml.min-1.g-1, respectively (P < 0.001).

CONCLUSION

The combination of EBT three-dimensional reconstruction and flow study can be more effective in the assessment of CABG anatomy and quantification of patent CABG blood flow.

A kinetic model for the metabolic interaction of two substrates at the active site of cytochrome P450 3A4

In many cases, CYP3A4 exhibits unusual kinetic characteristics that result from the metabolism of multiple substrates that coexist at the active site. In the present study, we observed that alpha-naphthoflavone (alpha-NF) exhibited a differential effect on CYP3A4-mediated product formation as shown by an increase and decrease, respectively, of the carboxylic acid (P(2)) and omega-3-hydroxylated (P(1)) metabolites of losartan, while losartan was found to be an inhibitor of the formation of the 5,6-epoxide of alpha-NF. Thus, to address this problem, a kinetic model was developed on the assumption that CYP3A4 can accommodate two distinct and independent binding domains for the substrates within the active site, and the resulting velocity equations were employed to predict the kinetic parameters for all possible enzyme-substrate species. Our results indicate that the predicted values had a good fit with the experimental observations. Therefore, the kinetic constants can be used to adequately describe the nature of the metabolic interaction between the two substrates. Applications of the model provide some new insights into the mechanism of drug-drug interactions at the level of CYP3A4.

Optimal electrocardiographically triggered phase for reducing motion artifact at electron-beam CT in the coronary artery

RATIONALE AND OBJECTIVES

The authors performed this study to (a) investigate coronary movement with electron-beam computed tomography (CT) and (b) find the optimal electrocardiographic (ECG) triggering phase for eliminating motion artifact.

MATERIALS AND METHODS

One hundred fifty-one patients without arrhythmia were examined with electron-beam CT. First, movie scans were obtained to create displacement and velocity graphs of coronary artery movement. Then, a volume scan with an exposure time of 100 msec was obtained with various ECG trigger settings.

RESULTS

Movement patterns of coronary arteries varied with heart rate. Optimal triggering phase was before atrial systole (near 71% of the R-R interval) when heart rate was slower than 68 beats per minute and at ventricular end systole when heart rate was fast. Rate of severe motion artifacts decreased from 43% to 0% when triggering was altered from 80% of the R-R interval to the individual optimal value. Experimental values of the optimal phase at different heart rates were derived, and severe motion artifact was only 3.0% with these values.

CONCLUSION

ECG triggering set according to the heart rate enables a great reduction in motion artifacts at electron-beam CT with a 100-msec exposure time. The results may have implications for magnetic resonance imaging of the coronary artery.

[Studies on adsorption of the organic phosphorus pesticide with the macroporous resin]

Macroporous adsorbing resins prepared by styrene are selected as absorbent in the static and dynamic adsorption experiments of organic phosphorus pesticide. These resins are attempted to be applied in blood purification to detoxify and save the patient's life.

Effects of scanning and reconstruction parameters on image quality in electron-beam CT angiography: coronary artery phantom study

RATIONALE AND OBJECTIVES

This study compared the image quality obtained with different scanning and reconstruction parameters for electron-beam computed tomographic (CT) angiography and sought optimal methods for visualizing the coronary artery lumen.

MATERIALS AND METHODS

Electron-beam CT angiography with contrast material enhancement was used to image 35 branches of fresh postmortem swine coronary arteries. Different collimation widths, fields of view (FOVs), reconstruction kernels, and algorithms were employed to reconstruct the acquired raw data into CT angiographic images. Image quality was compared and analyzed.

RESULTS

The contrast-to-noise ratios (C/Ns) for 1.5-, 2-, and 3-mm section thickness were 28.4 +/- 15.2, 31.9 +/- 9.3, and 33.8 +/- 14.5, respectively (P < .05). The lengths of visualized coronary artery lumina were significantly longer for 1.5-mm scanning (71.6 mm +/- 4.3) than for 2-mm (58.3 mm +/- 5.5) and 3-mm scanning (59.0 mm +/- 8.0) (P < .01). The C/Ns for 12.7-, 18.0-, and 26.0-cm FOV reconstruction were 32.8 +/- 9.9, 28.9 +/- 8.2, and 27.1 +/- 8.2, respectively (not significant), and the visualized luminal lengths were 76.1 mm +/- 12.5, 71.7 mm +/- 14.6, and 65.4 mm +/- 13.1, respectively (not significant). The highest C/N (48.2 +/- 13.3) was achieved with smooth kernels and a cone-beam algorithm, and the lowest (14.7 +/- 3.4) with very sharp kernels and a normal algorithm. Cone-beam algorithm images had significantly higher C/Ns than did normal algorithm images (P < .001), and they demonstrated longer coronary artery lumina (P < .01).

CONCLUSION

Collimation width, FOV, reconstruction kernels, and algorithms are important in the processing of high-quality electron-beam coronary angiograms. A 1.5-mm collimation width, 12.7-cm FOV, cone-beam reconstruction algorithm, and very sharp kernels should help in obtaining the best image quality and depicting the longest segments of coronary artery lumen.

Evaluation of electron beam tomographic coronary arteriography with three-dimensional reconstruction in healthy subjects

In this study, the authors evaluated the performance characteristics of contrast-enhanced electron-beam tomography (EBT) with three-dimensional reconstruction in defining the coronary artery lumen in healthy subjects. Thirty patients with normal coronary angiograms by selective coronary arteriography (SCA) underwent contrast-enhanced EBT examination. Measured parameters included degree of luminal enhancement, intravascular contrast-to-noise ratio (CNR), and diameter and length of visualized lumen. Ventricular cavity, aortic blood pool, and coronary artery attenuation were found to be significantly different before and after intravenous injection of contrast material (p < 0.001). CNR decreased from proximal to distal segments within each vessel (p < 0.001), with a peak of 11.2 +/- 2.3 occurring in the proximal left anterior descending coronary artery (LAD) to a low of 4.8 +/- 2.0 in the distal left circumflex (LCX). Luminal diameters visualized by EBT had no significant difference with that of SCA (p > 0.05). Therefore, EBT angiography with three-dimensional reconstruction allows for noninvasive coronary arteriography revealing long segments of the major coronary arteries in normal subjects.

c-Jun NH2-terminal kinase targeting and phosphorylation of heat shock factor-1 suppress its transcriptional activity

The mammalian heat shock transcription factor HSF-1 regulates the expression of the heat shock proteins, molecular chaperones that are involved in cellular processes from higher order assembly to protein degradation. HSF-1 is a phosphorylated monomer under physiological growth conditions and is located mainly in the cytoplasm. Upon activation by a variety of environmental stresses, HSF-1 is translocated into the nucleus, forms trimers, acquires DNA binding activity, is hyperphosphorylated, appears as punctate granules, and increases transcriptional activity of target genes. As cells recover from stress, the punctate granules gradually disappear, and HSF-1 appears in a diffused staining pattern in the cytoplasm and nucleus. We have previously shown that the mitogen-activated protein kinase ERK phosphorylates and suppresses HSF-1-driven transcription. Here, we show that c-Jun NH(2)-terminal kinase (JNK) also phosphorylates and inactivates HSF-1. Overexpression of JNK facilitates the rapid disappearance of HSF-1 punctate granules after heat shock. Similar to ERK, JNK binds to HSF-1 in the conserved mitogen-activated protein kinases binding motifs and phosphorylates HSF-1 in the regulatory domain. The overexpression of an HSF-1-green fluorescent protein fusion construct lacking JNK phosphorylation sites causes this HSF-1 mutant to form nuclear granules that remain longer in the nucleus after heat shock. Taken together, these findings indicate that JNK phosphorylates HSF-1 and suppresses its transcriptional activity by rapidly clearing HSF-1 from the sites of transcription.

The human peroxisome proliferator-activated receptor alpha gene: identification and functional characterization of two natural allelic variants

Peroxisome proliferator-activated receptor (PPAR)alpha-null mice have a defect in fatty acid metabolism but reproduce normally. The lack of a detrimental effect of the null phenotype in development and reproduction opens up the possibility for null or variant PPARalpha gene (PPARA) alleles in humans. To search the coding region and splice junctions for mutant and variant PPARalpha alleles, the human PPARalpha gene was cloned and characterized, and sequencing by polymerase chain reaction was carried out. Two point mutations in the human gene were found in the DNA binding domain at codons for amino acids 131 and 162. The allele containing the mutation in codon 162 (CTT to GTT, L162V) designated PPARA*3, was found at a high frequency in a Northern Indian population. Transfection assays of this mutant showed that the non-ligand dependent transactivation activity was less than one-half as active as the wild-type receptor. PPARA*3 was also unresponsive to low concentrations of ligand as compared to the wild-type PPARA*1 receptor. However, the difference is ligand concentration-dependent; at concentrations of the peroxisome proliferator Wy-14 643 > 25 microM, induction activity was restored in this variant's transactivation activity to a level five-fold greater as compared with wild-type PPARA*1 with no ligand. The mutation in codon 131 (CGA to CAA, R131Q), designated PPARA*2 is less frequent than PPARA*3, and the constitutive ligand independent activity was slightly higher than PPARA*1. Increasing concentrations of Wy-14 643 activated PPARA*2 similar to that observed with PPARA*1. The biological significance of these novel PPARalpha alleles remains to be established. It will be of great interest to determine whether these alleles are associated with differential response to fibrate therapy.

Conformational modulation of human cytochrome P450 2E1 by ethanol and other substrates: a CO flash photolysis study

The alcohol-inducible cytochrome P450 2E1 is a major human hepatic P450 which metabolizes a broad array of endogenous and exogenous compounds, including ethanol, low-molecular weight toxins, and fatty acids. Several substrates are known to stabilize this P450 and inhibit its cellular degradation. Furthermore, ethanol is a known modulator of P450 2E1 substrate metabolism. We examined the CO binding kinetics of P450 2E1 after laser flash photolysis of the heme-CO bond, to probe the effects of ethanol and other substrates on protein conformation and dynamics. Ethanol had an effect on the two kinetic parameters that describe CO binding: it decreased the rate of CO binding, suggesting a decrease in the protein's conformational flexibility, and increased the photosensitivity, which indicates a local effect in the active site region such as strengthening of the heme-CO bond. Other substrates decreased the CO binding rate to varying degrees. Of particular interest is the effect of arachidonic acid, which abolished photodissociation in the absence of ethanol but had no effect in the presence of ethanol. These results are consistent with a model of P450 2E1 whereby arachidonic acid binds along a long hydrophobic binding pocket and blocks exit of CO from the heme region.

[Mobilization of autologous peripheral blood stem cells by chemotherapy and recombinant granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF)]

OBJECTIVE

To observe the efficacy of chemotherapy and recombinant granulocyte colony-stimulating factor (G-CSF, Glycosylated) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in autologous peripheral blood stem cells (APBSC) mobilization.

METHODS

The mobilization regimen: CBP 350 mg/m(2) intravenously injected at day 1, Vp16 350 mg/m(2) intravenously injected from day 1 to day 3. G-CSF and GM-CSF 5 microg x kg(-1) x d(-1) each, subcutaneously injected and DXM 5 mg/d intramuscularly injected, from the day of white blood cell (WBC) recovery to (2.4 - 6.4) x 10(9)/L from nadir to the day before the end of APBSC harvesting. APBSC harvesting started when WBC > 20.0 x 10(9)/L and ended when accumulated mononuclear cells (MNC) > 5 x 10(8)/kg. CFU-GM assay and CD(34)(+) cells counting of the APBSC were performed.

RESULTS

Twenty cases underwent APBSC mobilization. APBSC harvest began at day 22.15 +/- 3.66 for two successive days. Accumulated MNC was (5.93 +/- 1.62) x 10(8)/kg, CD(34)(+) cells (23.10 +/- 11.53) x 10(6)/kg and CFU-GM (3.44 +/- 2.85) x 10(5)/kg. No severe toxicity was observed. Hematopoiesis was well reconstituted in 8 patients received single and in 1 patient received double APBSC transplantations.

CONCLUSION

Chemotherapy combined with G-CSF + GM-CSF was a safe and highly effective method for APBSC mobilization.

Assessment of specificity of eight chemical inhibitors using cDNA-expressed cytochromes P450

1. The selectivity of eight chemical inhibitors has been extensively evaluated with 10 cDNA-expressed human cytochrome P450 isoforms (CYP). The results indicate that sulphaphenazole, quinidine and alpha-naphthoflavone are selective inhibitors of CYP2C9 (IC50 = 0.5-0.7 microM), CYP2D6 (0.3-0.4 microM) and CYP1A (0.05-5 microM) respectively on the basis of the IC50, which are much lower than those of other P450 isoforms (> 10-fold). 2. Ketoconazole exhibited potent inhibition of both CYP3A4-catalysed metabolism of phenanthrene, testosterone, diazepam (IC50 = 0.03-0.5 microM) and CYP1A1-catalysed deethylation of 7-ethoxycoumarin (0.33 microM). The selectivity of ketoconazole for other P450s was highly related to the concentration used. 3. Diethyldithiocarbamate, orphenadrine and furafylline were shown separately to be less selective inhibitors of CYP2E1, CYP2B6 and CYP1A isoforms by a broad range of IC50 that overlap those observed with other P450 isoforms. 4. Furafylline, quinidine and alpha-naphthoflavone activated CYP3A4-catalysed phenanthrene metabolism by 1.7-, 2- and 15-fold respectively. 5. The selectivity of orphenadrine and ketoconazole was further examined by using inhibitory monoclonal antibodies (MAb). Inhibitory MAb specific for the individual P450 isoforms may be of greater value than chemical inhibitors.

Molecular modeling of mammalian cytochrome P450s

The cytochrome P450s are a superfamily of hemoprotein enzymes responsible for the metabolism of a wide variety of xenobiotic and endogenous compounds. The individual P450s exhibit unique substrate specificity and stereoselectivity profiles which reflect corresponding differences in primary sequence and tertiary structure. In the absence of an experimental structure models for mammalian P450s have been generated by their homology with bacterial P450s of known structure. The rather low sequence identity between target and template proteins renders P450 modeling a challenging task. However, the substrate recognition properties of several P450s are consistent with recently developed working models. This review summarizes the major concepts and current approaches of molecular modeling of P450s.

A comparison of 99Tcm-MIBI myocardial SPET and electron beam computed tomography in the assessment of coronary artery disease in two different age groups

The aim of this study was to compare the clinical value of 99Tcm-MIBI single photon emission tomography (SPET) and electron beam computed tomography (EBCT) in the assessment of coronary artery disease (CAD) in different age groups. 99Tcm-MIBI SPET (stress-rest), EBCT and coronary angiography studies were performed in 64 consecutive patients with suspected CAD. The patients were classified into two groups: Group A = 40 patients > 45 years of age and Group B = 24 patients < or = 45 years of age. There were 31 and 14 patients with coronary stenosis > or = 50% as determined by coronary angiography in Groups A and B, respectively. All patients (30 cases) with abnormal 99Tcm-MIBI myocardial SPET and coronary calcification detected by EBCT had significant coronary artery disease, and 93.3% of the patients with normal 99Tcm-MIBI SPET and normal EBCT had normal coronary angiography or < 50% lumen narrowing of the coronary arteries. In Group B, the sensitivity of SPET for detecting CAD was significantly higher than that of EBCT (92.9 vs 42.9%, P < 0.01); the specificity of SPET was comparable to that of EBCT. In Group A, there was no significant difference between SPET and EBCT in terms of sensitivity (93.6 vs 90.3%) or specificity (88.9 vs 55.6%). However, in the detection of individual coronary artery disease, the specificity of SPET was significantly higher than that of EBCT in Group A (94.1 vs 66.7%, P < 0.001). The sensitivity of SPET was again significantly higher than that of EBCT (85.7 vs 38.1%, P < 0.005) in Group B. The accuracy of SPET was higher than that of EBCT in both groups (82.5 vs 67.5%, P < 0.01 in Group A; 93.1 vs 76.4%, P < 0.01 in Group B, respectively). We conclude that 99Tcm-MIBI myocardial perfusion SPET has a higher sensitivity than EBCT in the detection of CAD in patients < or = 45 years old and a higher specificity in patients > 45 years of age. A combination of SPET and EBCT may assess CAD more accurately.

Synthetic peptide mimics of a predicted topographical interaction surface: the cytochrome P450 2B1 recognition domain for NADPH-cytochrome P450 reductase

In order to identify the cytochrome P450-binding domain for NADPH-cytochrome P450 reductase, synthetic peptide mimics of predicted surface regions of rat cytochrome P450 2B 1 were constructed and evaluated for inhibition of the P450-reductase interaction. A peptide corresponding to residues 116-134, which includes the C helix, completely inhibited reductase-mediated benzphetamine demethylation by purified P450 2B1. Replacement of Arg-125 by Glu yielded a noninhibitory peptide, suggesting that this residue significantly contributes to the reductase-P450 interaction. Additional P450 peptides were prepared which correspond to combinations of regions distant in primary sequence, but predicted to be spatially proximate. A peptide derived from segments of the C and L helices was a more potent inhibitor than peptides derived from either segment alone. This topographically designed peptide not only inhibited P450 2B1 in its purified form, but also when membrane-bound in rat liver microsomes. The peptide also inhibited microsomal aryl hydrocarbon hydroxylase, aniline hydroxylase, and erythromycin demethylase activities derived from other P450s. These results indicate that the C and L helices contribute to a reductase-binding site common to multiple P450s, and present a peptide mimic for this region that is useful for inhibition of P450-mediated microsomal activities.

Detection and analysis of intracoronary artery stent after PTCA using contrast-enhanced three-dimensional electron beam tomography

We evaluated several three-dimensional methods of contrast-enhanced electron beam tomography (EBT) for evaluation of intracoronary stent characteristics after percutaneous transluminal coronary angioplasty (PTCA). Twenty-six patients who had undergone PTCA and stenting (31 stents) were investigated by using contrast-enhanced, electrocardiographically (ECG) triggered EBT scanning. EBT results were compared with conventional selective coronary arteriography (SCA). Overall, 27 intracoronary stents had been identified on EBT images (87.1%), while 4 stents could not be evaluated because of impaired image quality. EBT correctly identified the only case in which there was a residual stenosis at the distal portion of the stent. As compared with SCA results, EBT showed an over-estimation of intracoronary stent diameter (p < 0.001) and accurate measurement on the visualized length of the stents (p > 0.05). Fifty Hu, 100 Hu and 150 Hu were used as the observed window levels on three-dimensional (3-D) images; the accuracy for stent assessment increased with ascending window levels. EBT can reliably characterize coronary artery stents and may become a useful non-invasiveive method for patency evaluation of stented coronary segments after PTCA.

[Progress in technique of computer for three dimensional reconstruction from biological tissue series slices images]

The development of the technique of computer processing images and biotechnology from late 80's to early 90's has rovided the possibility of displaying three dimensional images of biological tissues truly. Now the technique of computer for three dimensional reconstruction is more and more widely used in the biological territory. This paper introduces the progress in the technique of computer for three dimensional reconstruction from biological tissue series slices images. Emphasis is laid on registration, reconstruction & display, image data compressing and image automatic segmentation.

Sigmoidal kinetic model for two co-operative substrate-binding sites in a cytochrome P450 3A4 active site: an example of the metabolism of diazepam and its derivatives

Cytochrome P450 3A4 (CYP3A4) plays a prominent role in the metabolism of a vast array of drugs and xenobiotics and exhibits broad substrate specificities. Most cytochrome P450-mediated reactions follow simple Michaelis-Menten kinetics. These parameters are widely accepted to predict pharmacokinetic and pharmacodynamic consequences in vivo caused by exposure to one or multiple drugs. However, CYP3A4 in many cases exhibits allosteric (sigmoidal) characteristics that make the Michaelis constants difficult to estimate. In the present study, diazepam, temazepam and nordiazepam were employed as substrates of CYP3A4 to propose a kinetic model. The model hypothesized that CYP3A4 contains two substrate-binding sites in a single active site that are both distinct and co-operative, and the resulting velocity equation had a good fit with the sigmoidal kinetic observations. Therefore, four pairs of the kinetic estimates (KS1, kalpha, KS2, kbeta, KS3, kdelta, KS4 and kgamma) were resolved to interpret the features of binding affinity and catalytic ability of CYP3A4. Dissociation constants KS1 and KS2 for two single-substrate-bound enzyme molecules (SE and ES) were 3-50-fold greater than KS3 and KS4 for a two-substrate-bound enzyme (SES), while respective rate constants kdelta and kgamma were 3-218-fold greater than kalpha and kbeta, implying that access and binding of the first molecule to either site in an active pocket of CYP3A4 can enhance the binding affinity and reaction rate of the vacant site for the second substrate. Thus our results provide some new insights into the co-operative binding of two substrates in the inner portions of an allosteric CYP3A4 active site.

Inhibition of human liver cytochrome P-450 1A2 by the class IB antiarrhythmics mexiletine, lidocaine, and tocainide

Mexiletine, lidocaine, and tocainide are class IB antiarrhythmic drugs that are used for the treatment of ventricular arrhythmias and are known to inhibit drug metabolism. The objectives of this study were to characterize the inhibitory effects of mexiletine, lidocaine, and tocainide on cytochrome P-450 1A2 (CYP1A2) activity in human liver microsomes and to evaluate their relative inhibitory potencies by using a molecular model of this P-450 isozyme. The inhibitory effect of mexiletine, lidocaine, and tocainide on cytochrome CYP1A2 in human liver microsomes was examined with methoxyresorufin O-demethylase activity as an index of the catalytic activity of this P-450 isozyme. The kinetic inhibition types and Ki values were determined by Lineweaver-Burk plots and Dixon plots, respectively. Molecular modeling was used to assess the interaction of these agents with the CYP1A2 active site. Methoxyresorufin O-demethylase activity was inhibited 67 +/- 8%, 20 +/- 5%, and 7 +/- 4% by 2 mM mexiletine, lidocaine, and tocainide, respectively. Mexiletine and lidocaine exhibited competitive inhibition with Ki values of 0.28 +/- 0.12 mM and 1.54 +/- 0.74 mM, respectively, whereas the inhibition type of tocainide could not be determined because of its weak potency. A charge interaction between mexiletine and the Asp313 side chain in the CYP1A2 active site was found, and varying degrees of hydrogen bond formation between these three compounds and the CYP1A2 active site were observed. The in vitro inhibitory potencies in human liver microsomes (mexiletine > lidocaine > tocainide) are consistent with the structural interactions found in a molecular model of the active site of CYP1A2.