Deep learning with convolutional neural network for estimation of the characterisation of coronary plaques: Validation using IB-IVUS

INTRODUCTION

Deep learning approaches have shown high diagnostic performance in image classifications, such as differentiation of malignant tumors and calcified coronary plaque. However, it is unknown whether deep learning is useful for characterizing coronary plaques without the presence of calcification using coronary computed tomography angiography (CCTA). The purpose of this study was to compare the diagnostic performance of deep learning with a convolutional neural network (CNN) with that of radiologists in the estimation of coronary plaques.

METHODS

We retrospectively enrolled 178 patients (191 coronary plaques) who had undergone CCTA and integrated backscatter intravascular ultrasonography (IB-IVUS) studies. IB-IVUS diagnosed 81 fibrous and 110 fatty or fibro-fatty plaques. We manually captured vascular short-axis images of the coronary plaques as Portable Network Graphics (PNG) images (150 × 150 pixels). The display window level and width were 100 and 700 Hounsfield units (HU), respectively. The deep-learning system (CNN; GoogleNet Inception v3) was trained on 153 plaques; its performance was tested on 38 plaques. The area under the curve (AUC) obtained by receiver operating characteristic analysis of the deep learning system and by two board-certified radiologists was compared.

RESULTS

With the CNN, the AUC and the 95% confidence interval were 0.83 and 0.69-0.96, respectively; for radiologist 1 they were 0.61 and 0.42-0.80; for radiologist 2 they were 0.68 and 0.51-0.86, respectively. The AUC for CNN was significantly higher than for radiologists 1 (p = 0.04); for radiologist 2 it was not significantly different (p = 0.22).

CONCLUSION

DL-CNN performed comparably to radiologists for discrimination between fatty and fibro-fatty plaque on CCTA images.

IMPLICATIONS FOR PRACTICE

The diagnostic performance of the CNN and of two radiologists in the assessment of 191 ROIs on CT images of coronary plaques whose type corresponded with their IB-IVUS characterization was comparable.

Diagnostic performance of computed tomography digital subtraction angiography of the lower extremities during haemodialysis in patients with suspected peripheral artery disease

INTRODUCTION

With intra-arterial digital subtraction angiography (DSA) considered as the gold standard, we compared the diagnostic value of computed tomography angiography (CTA) and computed tomography-digital subtraction angiography (CT-DSA in hemodialysis (HD) patients suspected of having lower limb peripheral artery disease (PAD).

METHODS

In this retrospective study, we enrolled 220 HD patients with suspected PAD. CT-DSA images were obtained by subtracting unenhanced images from enhanced images. The research team calculated the area under the curve (AUC), sensitivity, specificity, positive and negative predictive value (PPV, NPV), and recorded the diagnostic accuracy between the CTA and CT-DSA images using the DSA as gold standard. Visual evaluation of calcifications in the peripheral arteries were also compared between CTA and CT-DSA images.

RESULTS

At the above-knee level, the CTA AUC [95% confidence interval (CI)] was 0.68 (CI 0.64-0.72), sensitivity and specificity were 60 and 81%, PPV and NPV were 85 and 53%, and accuracy was 67%. Below the knee, these values were 0.66 (CI 0.62-0.70), 71 and 79%, 79 and 47%, and 66%. For CT-DSA, above-knee, the AUC [95% CI] was 0.88 (CI 0.85-0.91), sensitivity and specificity were 84 and 92%, PPV and NPV were 89 and 97%, and accuracy was 93%. Below the knee, these values were 0.95 (CI 0.93-0.97), 95 and 93%, 96 and 83%, and 93%. The scores for the visualization of calcification in the peripheral arteries was significantly higher for CT-DSA than CTA (p < 0.05).

CONCLUSIONS

CT-DSA helps to assess stenotic PAD with high calcification in the lower extremities of HD patients.

IMPLICATIONS FOR PRACTICE

On CT-DSA images, the severity of vascular calcification can be assessed for HD patients suspected of PAD of the lower extremities.

A New Grip Strength Measuring Device for Detailed Evaluation of Muscle Contraction among the Elderly

BACKGROUND

We developed a new grip strength measuring device, which considers the time axis, for evaluating muscle contraction in detail in elderly people.

OBJECTIVES

To present the novel device and preliminary results concerning agility in gripping.

DESIGN

Cross-sectional analysis.

PARTICIPANTS

One hundred and twenty-one older persons (48 men and 73 women, mean age 74.4 years) referring for memory disorders to the outpatient clinic of our institute.

MEASUREMENTS

A novel device taking advantage of an industrial force-gauge was developed for measuring gripping performance. The instrument graphically described participants' strength production. Nine indices were derived from four points identified by the graph: 1) starting point ("Go signal"), 2) time when gripping starts, 3) turning point (TP) when the inclination of the curve depicting strength production changes, and 4) peak of strength production. Results obtained from the study sample of older persons were compared (as ratios) to a control group of 30 healthy young adults in their thirties in order to calculate age-related decline rates. Differences between right and left side were compared.

RESULTS

A significant difference was observed between right and left hands concerning the time to reach peak of strength, and time from TP to strength peak in both men and women. For women, the following indices were also significantly different: time to reach TP, strength at TP, time from TP to strength peak, curve inclination from TP to strength peak, and ratio of TP strength divided by peak strength.

CONCLUSION

Declines in several indices of gripping agility were measured. The parameters which were more closely related to time than strength itself showed significant differences between right and left hands, especially in women.

Drug delivery observation of hydrophobe ferrofluid and magnetite nanoparticals by SPring-8 synchrotron radiation

In this study, the composite magnetic nanoparticles of coated SiO nano film with about 8 nm size and high saturation magnetization value, were synthesized by liquid phase precipitation method. The magnetic nanoparticles can be dispersed in various liquid media, widely known as magnetic fluids or ferrofluids with both magnetic and liquid properties. The materials been collected great interests and more and more attentions to focus into Drug Delivery System (DDS) as a new technology in this paper. We use the composite nanoparticles to disperse H2O and inject the solutions into rat's in-vivo organs. And, in the experiments by using a strong photon beam of SPring-8 Synchrotron Radiation facility, the distribution stat and the effects of magnetic field as well as drug delivery behaviour of nanoparticles in the rat' kidney are verified by the in-vivo observations.

Cerebral venous thrombosis in adult nephrotic syndrome due to systemic amyloidosis

Although venous thrombosis is one of the common complications in nephrotic patients, cerebral venous thrombosis (CVT) is rarely reported. CVT is so difficult to be detected by conventional diagnostic methods that it is sometimes overlooked despite its potential severity. We report a 79-year-old female with nephrotic syndrome due to systemic amyloidosis who suddenly altered mental status during her hospitalization. The underlying etiology had been not identified by physical examinations, various laboratory data, and repeated computed tomography, and finally she died. The post-mortem examination showed a massive thrombus impacted in intracranial left-sided transverse and sigmoid sinus. This case suggests that CVT can occur in a nephrotic patient who presents unexplained neurological signs and symptoms, which might not be detected only through conventional diagnostic tests.

Microbial community analysis in the denitrification process of saline-wastewater by denaturing gradient gel electrophoresis of PCR-amplified 16S rDNA and the cultivation method

The metallurgic wastewater generated from the processes of recovering precious metals from industrial wastes contains high concentrations of nitrogen compounds and salts. Biological nitrogen removal from this wastewater was attempted using a circulating bioreactor system equipped with an anaerobic packed bed or an anaerobic fluidized bed. The denitrification capability of the system with the anaerobic packed bed was more stable than that of the system with the anaerobic fluidized bed. The NOx removal rate of the anaerobic packed bed was as high as 97%. Microbial community analysis by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA (rDNA) fragments and the cultivation method revealed that the community diversity varied in accordance with wastewater composition such as the level of salinity and so on. Phylogenetic analysis suggested that the taxonomic affiliation of the dominant species in the anaerobic reactors was to the gamma-Proteobacteria including Halomonadaceae species. The PCR-DGGE method as a non-cultivation method was found to be a powerful tool for analysis of the microbial community, because the cultivation method could detect only a fraction of the microbial species present in these systems. The genetic diversity of the isolated bacteria belonging to the gamma-Proteobacteria which reduced both nitrate and nitrite in the anaerobic packed bed was higher than that of the bacteria in the anaerobic fluidized bed. This suggested that a genetically diverse microbial community stabilized the denitrifying performance in the anaerobic packed bed.

Toroidal plasma rotation induced by the dynamic ergodic divertor in the TEXTOR tokamak

The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating in the m/n=3/1 mode configuration, are presented. The deeply penetrating external magnetic field perturbation of this configuration increases the toroidal plasma rotation. Staying below the excitation threshold for the m/n=2/1 tearing mode, this toroidal rotation is always in the direction of the plasma current, even if the toroidal projection of the rotating magnetic field perturbation is in the opposite direction. The observed toroidal rotation direction is consistent with a radial electric field, generated by an enhanced electron transport in the ergodic layers near the resonances of the perturbation. This is an effect different from theoretical predictions, which assume a direct coupling between rotating perturbation and plasma to be the dominant effect of momentum transfer.

Analysis of pathological risk factors for lymph node metastasis of submucosal invasive colon cancer

There are currently no universally accepted indications and criteria for additional surgical resection of the colorectum after endoscopic resection of the submucosal invasive cancer. The purpose of the present study is to establish accurate indications and criteria for additional surgical resection of the colorectum, based on the prediction of lymph node metastasis, after endoscopic resection of the submucosal invasive cancer. We investigated 140 submucosal invasive colorectal cancers and analyzed the pathologic factors of lymph node metastasis. The tumors were evaluated for pathologic factors in the invasive area of the submucosal carcinoma and were compared between the cases with lymph node metastasis and those without lymph node metastasis. Lymph node metastasis was observed in 13 cases (9%). Univariate logistic regression analysis showed that the depth of invasion, cribriform-type structural atypia, absence of lymphoid infiltration, lymphatic permeation, and venous permeation were statistically significant as risk factors for lymph node metastasis. Multivariate logistic regression analysis showed that the important risk factors included, in decreasing order, lymphatic permeation, absence of lymphoid infiltration, cribriform-type structural atypia, venous permeation, and depth of invasion. Submucosal invasion of 2 mm or more, and/or, depth of lymphatic permeation of 2 mm or more are risk factors for lymph node metastasis. The pathologic criteria based on our results for additional colectomy enables greater accuracy selection of patients who will undergo further surgical treatment after endoscopic resection.

Comparative analysis of genetic diversity and expression of amoA in wastewater treatment processes

The genetic diversity and expression of amoA of autotrophic ammonia oxidizers in wastewater treatment processes were investigated by RT-PCR and denaturing gradient gel electrophoresis (DGGE) in order to identify active components of ammonia-oxidizer populations in a such processes. Ammonia oxidizers, evidenced by the presence of amoA mRNA, were regarded as metabolically active. The DGGE profiles derived from amoA mRNA and from its gene, which were amplified by RT-PCR or PCR using samples collected from a bench-scale reactor treating high concentration of inorganic ammonia, were similar. In contrast, RNA and DNA-derived DGGE profiles from three domestic wastewater treatment facilities were different from each other. These data indicate that the dominant ammonia oxidizers in the bench-scale reactor exhibited ammonia-oxidizing activity, whereas some ammonia oxidizers in the domestic wastewater treatment facilities apparently did not express high levels of amoA mRNA.

Sawtooth oscillation in current-carrying plasma in the large helical device

Sawtooth oscillations have been observed in current-carrying helical plasmas by using electron-cyclotron-emission diagnostics in the Large Helical Device. The plasma current, which is driven by neutral beam injection, reduces the beta threshold of the sawtooth oscillation. When the central q value is increased due to the plasma current, the core region crashes, and, when it is decreased, the edge region crashes annularly. Observed rapid mixture of the plasma in the limited region suggests that these sawtooth crashes are reconnection phenomena. Unlike previous experiments, no precursor oscillation has been observed.

Effects of SRT and DO on N2O reductase activity in an anoxic-oxic activated sludge system

Nitrous oxide (N2O) is emitted from wastewater treatment processes, and is known to be a green house gas contributing to global warming. It is thus important to develop technology that can suppress N2O emission. The effects of sludge retention time (SRT) and dissolved oxygen (DO) on N2O emission in an anoxic-oxic activated sludge system were estimated. Moreover, the microbial community structure in the sludge, which plays an important role in N2O suppression, was clarified based on nitrous oxide reductase (nosZ) gene analysis by molecular biological techniques. The results showed that under low SRT conditions, nitrification efficiency was reduced and the N2O emission rate in the oxic reactors was increased. It was also observed that N2O emission was enhanced under low DO conditions, where the available oxygen is insufficient for nitrification. Moreover, molecular analysis revealed that the clones identified in this study were closely related to Ralstonia eutropha and Paracoccus denitrificans. The fact that the identified sequences are not closely related to known culturable denitrifier nosZ sequences indicates a substantial in situ diversity of denitrifiers contributing to N2O suppression, which are not reflected in the cultivatable fraction of the population. The further application of these new molecular techniques should serve to enhance our knowledge of the microbial community of denitrifying bacteria contributing to N2O suppression in wastewater treatment systems.

Comparison of detection specificity of nitrifying bacteria in biofilm using fluorescence in situ hybridization and in situ fluorescent antibody methods

The in situ fluorescent antibody and fluorescence in situ hybridization (FISH) methods are very useful in the in situ detection of specific bacteria like nitrifiers in a biofilm. In this study, simultaneous staining using the FISH and in situ fluorescent antibody methods was examined. As a result, no specific fluorescence was observed with either method when FISH was performed followed by the in situ fluorescent antibody method; however, when the in situ fluorescent antibody method was performed first followed by FISH, specific fluorescence was observed in both cases. Moreover, it was suggested that the detection specificities of FISH and the in situ fluorescent antibody method are almost identical.

Island dynamics in the large-helical-device plasmas

In the Large Helical Device plasma discharges, the size of an externally imposed island with mode number ( n/m = 1/1) decreases substantially when the plasma is collisionless ( nu(*)< approximately 1) and the beta is finite ( > approximately 0.1%) at the island location. For the collisional plasmas with finite beta, on the other hand, the size of the island increases. However, there is a threshold in terms of the vacuum island size below which the island enlargement is not seen.

Characterization of microbial community in nitrogen removal process of metallurgic wastewater by PCR-DGGE

The metallurgic wastewater generated from the processes of recovering precious metals from industrial wastes contains high concentrations of nitrogen compounds such as ammonia and nitric acid and of salts such as sodium chloride and sodium sulfate. Biological nitrogen removal from this wastewater was attempted by a circulating bioreactor system equipped with an anoxic packed bed and an aerobic fluidized bed. The anoxic packed bed of this system was found to effectively remove nitrite and nitrate from the wastewater by denitrification at a removal ratio of 97%. As a result of denitrification activity tests at various NaCl concentrations, the sludge obtained from the anoxic packed bed exhibited accumulation of nitrite at 5.0 and 8.4% NaCl concentrations, suggesting that the reduction of nitrite is the key step in the denitrification pathway under hypersaline conditions. The microbial community analysis by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA (rDNA) fragments revealed that the community diversity varied in accordance with water temperature, nitrate-loading rate and ionic strength. When particular major DGGE bands were excised, reamplified and directly sequenced, the dominant species in the anoxic packed bed were affiliated with the beta and gamma subclasses of the class Proteobacteria such as Alcaligenes defragrans and Pseudomonas spp., respectively.

Community analysis of nitrifying bacteria in an advanced and compact Gappei-Johkasou by FISH and PCR-DGGE

Fluorescent in situ hybridization (FISH) method with 16S rRNA-targeted oligonucleotide probes was used for quantitative estimation of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in a Johkasou. Although the occupation ratios of AOB and NOB increased as nitrification progressed, about one month later, the occupation ratios decreased, despite showing good nitrification ability. Furthermore, even when urea was added to the feeding wastewater to raise the amount of T-N, the occupation ratios of both nitrifying bacteria remained constant. For further investigation, denaturing gradient gel electrophoresis (DGGE) was used to study the community structure of AOB in the Johkasou. As a result, DGGE band patterns and following sequence analysis revealed that the community structure of AOB was complicated and changed during this experiment. It was suggested that even if the occupation ratio of AOB to eubacteria was constant, the majorities of AOB were changed through temperature and load fluctuation. The combination of FISH and PCR-DGGE provides new information that was not available by conventional cultivation-based methods.

PCR-DGGE analysis of denitrifying bacteria in a metallurgic wastewater treatment process

The wastewater generated from the processes of recovering precious metals from industrial wastes contains high concentrations of acids such as nitric acid and of salts. Biological nitrogen removal from this wastewater was attempted by using a circulating bioreactor system equipped with an anoxic packed bed or an anoxic fluidized bed and an aerobic three-phase fluidized bed. The system was found to effectively remove nitrogen from the diluted wastewater (T-N; 1,000-4,000 mg litre(-1)). The microbial population structure of activated sludge in an anoxic reactor was analyzed by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA (rDNA) fragments. DGGE analysis under different operating conditions demonstrated the presence of some distinguishable bands in the separation pattern, which were most likely derived from many different species constituting the microbial communities. Furthermore, the population diversity varied in accordance with the nitrate-loading rate, water temperature and reactor condition. Some major DGGE bands were excised, reamplified and directly sequenced. It was revealed that the dominant population in the anoxic reactor were affiliated with the beta subclass of the class Proteobacteria.

Detection and quantification of expression of amoA by competitive reverse transcription-pCR

Ammonia oxidation by chemolithoautotrophic ammonia-oxidizing bacteria is an important step in the biological nitrogen removal process. The first conversion step, the oxidation of ammonia to hydroxylamine is catalyzed by ammonia monooxygenase (AMO). To investigate the activity of ammonia oxidation, mRNA (designated as amoA) encoding a subunit of AMO was quantified by competitive reverse transcription (RT)-PCR. As a result, it was possible to detect and quantify amoA expression in cultured Nitrosomonas europaea and even complex microbial communities such as nitrifying bacterial aggregates by competitive RT-PCR. It was estimated that amoA concentration in cultured N. europaea was 2.3 x 10(8) copies x ml(-1). Additionally, it was calculated that the copy number of amoA in nitrifying bacterial aggregates was 1.0 x 10(12) copies x ml(-1) (5.1 x 10(10) copies x mg(-1)-dry weight). On the other hand, amoA expression in the natural activated sludge in a household Gappei-Johkaso was undetectable, whereas 16S rRNA of ammonia-oxidizing bacteria was detected by RT-PCR. Then, four days cultivation of this sludge in inorganic artificial wastewater resulted in increasing amoA expression to a quantifiable amount by competitive RT-PCR. In conclusion, the competitive RT-PCR was effective to investigate the expression of amoA as an indicator of ammonia oxidation activity by autotrophic ammonia-oxidizing bacteria.

Direct detection by in situ PCR of the amoA gene in biofilm resulting from a nitrogen removal process

Ammonia oxidation is a rate-limiting step in the biological removal of nitrogen from wastewater. Analysis of microbial communities possessing the amoA gene, which is a small subunit of the gene encoding ammonia monooxygenase, is important for controlling nitrogen removal. In this study, the amoA gene present in Nitrosomonas europaea cells in a pure culture and biofilms in a nitrifying reactor was amplified by in situ PCR. In this procedure, fixed cells were permeabilized with lysozyme and subjected to seminested PCR with a digoxigenin-labeled primer. Then, the amplicon was detected with an alkaline phosphatase-labeled antidigoxigenin antibody and HNPP (2-hydroxy-3-naphthoic acid-2'-phenylanilide phosphate), which was combined with Fast Red TR, and with an Alexa Fluor 488-labeled antidigoxigenin antibody. The amoA gene in the biofilms was detected with an unavoidable nonspecific signal when the former method was used for detection. On the other hand, the amoA gene in the biofilms was detected without a nonspecific signal, and the cells possessing the amoA gene were clearly observed near the surface of the biofilm when Alexa Fluor 488-labeled antidigoxigenin antibody was used for detection. Although functional gene expression was not detected in this study, detection of cells in a biofilm based on their function was demonstrated.

[Neoadjuvant chemotherapy for advanced gastric cancer with para-aortic lymph node metastasis]

Neoadjuvant chemotherapy was applied to patients with advanced gastric cancer and confirmed para-aortic lymph node metastasis. Subjects were 7 patients. The response to the neoadjuvant chemotherapy was a PR in 5 cases, MR in 2 cases for the primary lesion and CR in 2 cases PR in 5 cases for the para-aortic lymph node metastasis. The grades of histological response assessed on the resected specimen were Grade 0 in three cases, Grade 1a in one, Grade 1b in one and Grade 2 in two. While there was no significant difference in survival rate between patient groups with and without neoadjuvant chemotherapy, the 2-year survival rate in patients with neoadjuvant chemotherapy was a good 42.9%, compared with 10% in patients groups without neoadjuvant chemotherapy. It is concluded that a better prognosis can be expected for advanced gastric cancer patients with neoadjuvant chemotherapy.

Observation of the "self-healing" of an error field island in the large helical device

It was observed that the vacuum magnetic island produced by an external error magnetic field in the large helical device shrank in the presence of plasma. This was evidenced by the disappearance of flat regions in the electron temperature profile obtained by Thomson scattering. This island behavior depended on the magnetic configuration in which the plasmas were produced.

A novel quinoline alkaloid possessing a 7-benzyl group from the centipede, Scolopendra subspinipes

The novel quinoline alkaloid scolopendrine was isolated from the centipede, Scolopendra subspinipes mutilans L. Koch. The structure was determined to be 2-hydroxy-7-[(4-hydroxy-3-methoxyphenyl)methyl]-3-methoxy-8-quinolyl sulfate on the basis of high-resolution electron-spray ionization mass spectroscopy and two-dimensional NMR spectral data. Unlike quinoline alkaloids so far reported, scolopendrine is unique in having a 7-benzyl moiety in the quinoline ring.

K-ras gene mutations in non-small cell lung cancer in Japanese

To evaluate the association of mutations in the K-ras gene with the incidence of non-small cell lung cancer (NSCLC) in Japanese patients, 410 patients treated surgically were studied. DNA was extracted from frozen specimens, and polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) hybridization assay was used to examine K-ras mutations in codons 12, 13 and 61. K-ras mutations were found in 33 patients (8.0%), and all were smokers or ex-smokers. There were no significant differences in clinical or pathological stage between wild-type cases and mutant cases. The most frequently identified mutation was a G-->T transversion (25/33, 75.8%) that resulted in the substitution of a glycine for a cysteine or a valine. Previous studies have shown that the majority of K-ras mutations among smokers are G-->T transversion. In our study, K-ras mutations were found only in smokers, and there was a high frequency of G-->T transversions. A clear correlation exists between smoking and K-ras gene mutations.

Reduction of ion thermal diffusivity associated with the transition of the radial electric field in neutral-beam-heated plasmas in the large helical device

Recent large helical device experiments revealed that the transition from ion root to electron root occurred for the first time in neutral-beam-heated discharges, where no nonthermal electrons exist. The measured values of the radial electric field were found to be in qualitative agreement with those estimated by neoclassical theory. A clear reduction of ion thermal diffusivity was observed after the mode transition from ion root to electron root as predicted by neoclassical theory when the neoclassical ion loss is more dominant than the anomalous ion loss.

Recovery of Infectious Human Parainfluenza Type 2 Virus from cDNA Clones and Properties of the Defective Virus without V-Specific Cysteine-Rich Domain

A full-length cDNA clone was constructed from the genome of the human parainfluenza type 2 virus (hPIV2). First, Vero cells were infected with recombinant vaccinia virus expressing T7 RNA polymerase, and then the plasmid encoding the antigenome sequence was transfected into Vero cells together with polymerase unit plasmids, NP, P, and L, which were under control of the T7 polymerase promoter. Subsequently, the transfected cells were cocultured with fresh Vero cells. Rescue of recombinant hPIV2 (rPIV2) from cDNA clone was demonstrated by finding the introduced genetic tag. As an application of reverse genetics, we introduced one nucleotide change (UCU to ACU) to immediate downstream of the RNA-editing site of the V gene in the full-length hPIV2 cDNA and were able to obtain infectious viruses [rPIV2V(-)] from the cDNA. The rPIV2V(-) possessed a defective V protein that did not have the unique cysteine-rich domain in its carboxyl terminus (the V-protein-specific domain). The rPIV2V(-) showed no growth in CV-1 and FL cells. Replication of the rPIV2V(-) in these cells, however, was partially recovered by adding anti-interferon (IFN)-beta antibody into the culture medium, showing that the rPIV2V(-) is highly sensitive against IFN and that no growth of rPIV2V(-) in CV-1 and FL cells is mainly due to its hypersensitivity to endogenously produced IFN. These findings indicate that the V-protein-specific domain of hPIV2 is related to IFN resistance. On the other hand, the rPIV2V(-) efficiently replicated in Vero cells, which are known as a IFN-non-producers. However, the virus yields of rPIV2V(-) in Vero cells were 10- to100-fold lower than those of control rPIV2, although syntheses of the viral-specific proteins and their mRNAs in rPIV2V(-)-infected Vero cells were augmented up to 48 p.i. in comparison with those of rPIV2. Furthermore, the rPIV2V(-) virions showed anomalous in size as compared with rPIV2 virions. These results suggest that the V protein plays an important role in the hPIV2 assembly, maturation, and morphogenesis.

Intracellular transport of phosphatidic acid and phosphatidylcholine into lipid bodies in an oleaginous fungus, Mortierella ramanniana var. angulispora

Exogenous fluorescent phosphatidic acid (PA) and phosphatidylcholine (PC) were transported into lipid bodies in an oleaginous fungus, Mortierella ramanniana var. angulispora [Kamisaka et al. (1999) Biochim. Biophys. Acta 1438, 185-198]. We further investigated the processes of fluorescent PA and PC transport into lipid bodies in this fungus by changing culture conditions. Lowering incubation temperature decreased lipid body labeling by 1-palmitoyl, 2-[5-(5,7-dimethyl boron dipyrromethene difluoride)-1-pentanoyl]-PA (C5-DMB-PA), but fluorescence did not accumulate in organelles other than lipid bodies. C5-DMB-PC transport into lipid bodies was blocked at temperatures below 15 degrees C and fluorescence accumulated in intracellular membranes, presumably endoplasmic reticulum membranes. The low-temperature block of C5-DMB-PC transport enabled us to do pulse-chase experiments in which fungal cells were pulse-labeled at 15 degrees C with C5-DMB-PC and chased at 30 degrees C. The results clearly depicted transport of C5-DMB-PC and its derivatives from intracellular membranes to lipid bodies. Transport was temperature-dependent and ATP-dependent, although microtubules and actin filaments were not substantially involved. Experiments using 14C-labeled fatty acids and glycerol instead of C5-DMB-PC under the same conditions suggested that transport depicted by fluorescence agreed with metabolism and transport of PC containing native fatty acids. Furthermore, the transport mechanism preferred PC containing unsaturated fatty acids such as linoleic acid. This study dissect lipid transport of PA and PC into lipid bodies and reveal regulatory steps for lipid body formation in this fungus.

Intracellular transport of phosphatidic acid and phosphatidylcholine into lipid bodies: use of fluorescent lipids to study lipid-body formation in an oleaginous fungus

Fluorescent phosphatidic acid and phosphatidylcholine were used to characterize lipid-transport pathways into lipid bodies in an oleaginous fungus, Mortierella ramanniana var. angulispora. Several characteristics of the lipid transport such as temperature dependence and ATP dependence were evaluated. The transport depicted by these fluorescent lipids was consistent with metabolism of radiolabelled lipids, indicating that fluorescent lipids are useful to study lipid-body formation in this fungus. The results dissect lipid transport of phosphatidic acid and phosphatidylcholine into lipid bodies and reveal regulatory steps for lipid-body formation in this fungus.