A Comparative Analysis of Various Machine Learning Algorithms to Improve the Accuracy of HbA1c Estimation Using Wrist PPG Data

Due to the inconvenience of drawing blood and the possibility of infection associated with invasive methods, research on non-invasive glycated hemoglobin (HbA1c) measurement methods is increasing. Utilizing wrist photoplethysmography (PPG) with machine learning to estimate HbA1c can be a promising method for non-invasive HbA1c monitoring in diabetic patients. This study aims to develop a HbA1c estimation system based on machine learning algorithms using PPG signals obtained from the wrist. We used a PPG based dataset of 22 subjects and algorithms such as extreme gradient boosting (XGBoost), light gradient boosting machine (LightGBM), Categorical Boost (CatBoost) and random forest (RF) to estimate the HbA1c values. Note that the AC-to-DC ratios for three wavelengths were newly adopted as features in addition to the previously acquired 15 features from the PPG signal and a comparative analysis was performed between the performances of several algorithms. We showed that feature-importance-based selection can improve performance while reducing computational complexity. We also showed that AC-to-DC ratio (AC/DC) features play a dominant role in improving HbA1c estimation performance and, furthermore, a good performance can be obtained without the need for external features such as BMI and SpO2. These findings may help shape the future of wrist-based HbA1c estimation (e.g., via a wristwatch or wristband), which could increase the scope of noninvasive and effective monitoring techniques for diabetic patients.

Biopotentials of Collagen Scaffold Impregnated with Plant-Cell-Derived Epidermal Growth Factor in Defective Bone Healing

The combination of scaffolds with recombinant human epidermal growth factor (rhEGF) protein can enhance defective bone healing via synergistic activation to stimulate cellular growth, differentiation, and survival. We examined the biopotentials of an rhEGF-loaded absorbable collagen scaffold (ACS) using a mouse model of calvarial defects, in which the rhEGF was produced from a plant cell suspension culture system because of several systemic advantages. Here, we showed a successful and large-scale production of plant-cell-derived rhEGF protein (p-rhEGF) by introducing an expression vector that cloned with its cDNA under the control of rice α-amylase 3D promoter into rice calli (Oryza sativa L. cv. Dongjin). Implantation with p-rhEGF (5 μg)-loaded ACSs into critical-sized calvarial defects enhanced new bone formation and the expression of osteoblast-specific markers in the defected regions greater than implantation with ACSs alone did. The potency of p-rhEGF-induced bone healing was comparable with that of Escherichia coli-derived rhEGF protein. The exogenous addition of p-rhEGF increased the proliferation of human periodontal ligament cells and augmented the induction of interleukin 8, bone morphogenetic protein 2, and vascular endothelial growth factor in the cells. Collectively, this study demonstrates the successful and convenient production of p-rhEGF, as well as its potency to enhance ACS-mediated bone regeneration by activating cellular responses that are required for wound healing.

Optical Measurement of Molar Absorption Coefficient of HbA1c: Comparison of Theoretical and Experimental Results

Diabetes can cause dangerous complications if not diagnosed in a timely manner. The World Health Organization accepts glycated hemoglobin (HbA1c) as a measure of diagnosing diabetes as it provides significantly more information on the glycemic behavior from a single blood sample than the fasting blood sugar reading. The molar absorption coefficient of HbA1c is needed to quantify the amount of HbA1c present in a blood sample. In this study, we measured the molar absorption coefficient of HbA1c in the range of 450 nm to 700 nm using optical methods experimentally. We observed that the characteristic peaks of the molar absorption coefficient of HbA1c (at 545 nm and 579 nm for level 1, at 544 nm and 577 nm for level 2) are in close agreement with those reported in previous studies. The molar absorption coefficient values were also found to be close to those of earlier reports. The average molar absorption coefficient values of HbA1c were found to be 804,403.5 M−1cm−1 at 545 nm and 703,704.5 M−1cm−1 at 579 nm for level 1 as well as 503,352.4 M−1cm−1 at 544 nm and 476,344.6 M−1cm−1 at 577 nm for level 2. Our experiments focused on calculating the molar absorption coefficients of HbA1c in the visible wavelength region, and the proposed experimental method has an advantage of being able to easily obtain the molar absorption coefficient at any wavelength in the visible wavelength region. The results of this study are expected to help future investigations on noninvasive methods of estimating HbA1c levels.

Deep-Learning-Based Adaptive Symbol Decision for Visual MIMO System with Variable Channel Modeling

A channel modeling method and deep-learning-based symbol decision method are proposed to improve the performance of a visual MIMO system for communication between a variable-color LED array and camera. Although image processing algorithms using color clustering are available to correct distorted color information in a channel, color-similarity-based approaches are limited by real-world distortions; to overcome such limitations, symbol decision is defined as a multiclass classification problem. Further, to learn a robust classifier against channel distortion, a deep neural network learning technique is applied to adaptively determine symbols from channel distortion. The network designed herein comprises the channel identification and symbol decision modules; the channel identification module extracts a channel identification vector for symbol determination from an input image using a two-dimensional deep convolutional neural network (CNN); the symbol decision module then generates a feature map by combining the channel identification vector and information on adjacent symbols to determine the symbol via learning correlations between adjacent symbols using a one-dimensional CNN. The two modules are connected together and learned simultaneously in an end-to-end manner. We also propose a new channel modeling method that intuitively reflects real-world distortion factors rather than the conventional additive white Gaussian noise channel to efficiently train deep-learning networks. Lastly, in the proposed channel distortion environment, the proposed method shows performance improvement by an average of about 41.8% (up to about 54.8%) compared to the existing Euclidean distance method, and about 6.3% (up to about 9.2%) on average compared to the SVM method.

Cuffless Blood Pressure Estimation Based on Monte Carlo Simulation Using Photoplethysmography Signals

Blood pressure measurements are one of the most routinely performed medical tests globally. Blood pressure is an important metric since it provides information that can be used to diagnose several vascular diseases. Conventional blood pressure measurement systems use cuff-based devices to measure the blood pressure, which may be uncomfortable and sometimes burdensome to the subjects. Therefore, in this study, we propose a cuffless blood pressure estimation model based on Monte Carlo simulation (MCS). We propose a heterogeneous finger model for the MCS at wavelengths of 905 nm and 940 nm. After recording the photon intensities from the MCS over a certain range of blood pressure values, the actual photoplethysmography (PPG) signals were used to estimate blood pressure. We used both publicly available and self-made datasets to evaluate the performance of the proposed model. In case of the publicly available dataset for transmission-type MCS, the mean absolute errors are 3.32 ± 6.03 mmHg for systolic blood pressure (SBP), 2.02 ± 2.64 mmHg for diastolic blood pressure (DBP), and 1.76 ± 2.8 mmHg for mean arterial pressure (MAP). The self-made dataset is used for both transmission- and reflection-type MCSs; its mean absolute errors are 2.54 ± 4.24 mmHg for SBP, 1.49 ± 2.82 mmHg for DBP, and 1.51 ± 2.41 mmHg for MAP in the transmission-type case as well as 3.35 ± 5.06 mmHg for SBP, 2.07 ± 2.83 mmHg for DBP, and 2.12 ± 2.83 mmHg for MAP in the reflection-type case. The estimated results of the SBP and DBP satisfy the requirements of the Association for the Advancement of Medical Instrumentation (AAMI) standards and are within Grade A according to the British Hypertension Society (BHS) standards. These results show that the proposed model is efficient for estimating blood pressures using fingertip PPG signals.

Noninvasive In Vivo Estimation of Blood-Glucose Concentration by Monte Carlo Simulation

Continuous monitoring of blood-glucose concentrations is essential for both diabetic and nondiabetic patients to plan a healthy lifestyle. Noninvasive in vivo blood-glucose measurements help reduce the pain of piercing human fingertips to collect blood. To facilitate noninvasive measurements, this work proposes a Monte Carlo photon simulation-based model to estimate blood-glucose concentration via photoplethysmography (PPG) on the fingertip. A heterogeneous finger model was exposed to light at 660 nm and 940 nm in the reflectance mode of PPG via Monte Carlo photon propagation. The bio-optical properties of the finger model were also deduced to design the photon simulation model for the finger layers. The intensities of the detected photons after simulation with the model were used to estimate the blood-glucose concentrations using a supervised machine-learning model, XGBoost. The XGBoost model was trained with synthetic data obtained from the Monte Carlo simulations and tested with both synthetic and real data (n = 35). For testing with synthetic data, the Pearson correlation coefficient (Pearson’s r) of the model was found to be 0.91, and the coefficient of determination (R²) was found to be 0.83. On the other hand, for tests with real data, the Pearson’s r of the model was 0.85, and R² was 0.68. Error grid analysis and Bland–Altman analysis were also performed to confirm the accuracy. The results presented herein provide the necessary steps for noninvasive in vivo blood-glucose concentration estimation.

Systemic and Oral Immunogenicity of Porcine Epidemic Diarrhea Virus Antigen Fused to Poly-Fc of Immunoglobulin G and Expressed in ΔXT/FT Nicotiana benthamiana Plants

Porcine epidemic diarrhea virus (PEDV), a member of the Coronaviridae family has become increasingly probelmatic in the pig farming industry. Currently, there are no effective, globally applicable vaccines against PEDV. Here, we tested a recombinant PEDV vaccine candidate based on the expression of the core neutralising epitope (COE) of PEDV conjugated to polymeric immunoglobulin G scaffold (PIGS) in glycoengineered Nicotiana benthamiana plants. The biological activity of COE-PIGS was demonstrated by binding to C1q component of the complement system, as well as the surface of antigen-presenting cells (APCs) in vitro. The recombinant COE-PIGS induced humoral and cellular immune responses specific for PEDV after both systemic and mucosal vaccination. Altogether, the data indicated that PEDV antigen fusion to poly-Fc could be a promising vaccine platform against respiratory PEDV infection.

Local supplementation with plant-derived recombinant human FGF2 protein enhances bone formation in critical-sized calvarial defects

Numerous studies have demonstrated the advantages of plant cell suspension culture systems in producing bioactive recombinant human growth factors. This study investigated the biological activity of recombinant basic human fibroblast growth factor (rhFGF2) protein produced by a plant culture system to enhance new bone formation in a bone defect mouse model. The human FGF2 cDNA gene was cloned into a plant expression vector driven by the rice α-amylase 3D promoter. The vector was introduced into rice calli (Oryza sativa L. cv. Dongjin), and the clone with the highest expression of rhFGF2 was selected. Maximum accumulation of rhFGF2 protein (approximately 28 mg/l) was reached at 13 day post-incubation. Male C57BL/6 mice underwent calvarial defect surgery and the defects were loaded with absorbable collagen sponge (ACS) only (ACS group) or ACS impregnated with 5 μg of plant-derived rhFGF2 (p-FGF2) protein or E. coli-derived rhFGF2 (e-FGF2) protein. Similar to the effects of e-FGF2, local delivery with p-FGF2 enhanced bone healing in the damaged region to higher levels than the ACS group. Exogenous addition of p-FGF2 or e-FGF2 exhibited similar effects on proliferation, mineralization, and osteogenic marker expression in MC3T3-E1 cells. Together, the current findings support the usefulness of this plant-based expression system for the production of biologically active rhFGF2.

Peroxiredoxin I deficiency increases LPS‑induced lethal shock in mice

Peroxiredoxin I (Prx I) plays a role in regulating macrophage proinflammatory cytokine production and gene expression and participates in immune regulation. However, the possible protective role of Prx I in endotoxin‑induced lethal shock is poorly understood. In the present study, western blot analysis, ELISA and haematoxylin and eosin staining were performed to examine the protein expression of cytoines and analyses the levels of cytokines in the serum and tissue to evaluate the tissue damage. The present study revealed that lipopolysaccharide (LPS)‑induced lethality in Prx I‑/‑ mice was is accelerated via the observed decreased serum IL‑10 levels. Results also demonstrated rapid immune cell infiltration and oxidative stress in the Prx I‑/‑mice liver after LPS injections. These phenomena increased liver apoptosis through increasing cleaved caspase‑3 protein expression in Prx I‑/‑ mice after LPS injections, resulting in high lethality after LPS challenges. These findings provide a new insight for understanding the function of Prx I against endotoxin‑induced injury.

Recombinant human IGF-1 produced by transgenic plant cell suspension culture enhances new bone formation in calvarial defects

Transgenic plant cell suspension culture systems have been utilized extensively as convenient and efficient expression systems for the production of recombinant human growth factors. We produced insulin-like growth factor-1 using a plant suspension culture system (p-IGF-1) and explored its effect on new bone formation in calvarial defects. We also compared the bone regenerating potential of p-IGF-1 with commercial IGF-1 derived from Escherichia coli (e-IGF-1). Male C57BL/6 mice underwent calvarial defect surgery, and the defects were loaded with absorbable collagen sponge (ACS) only (ACS group) or ACS impregnated with 13μg of p-IGF-1 (p-IGF-1 group) or e-IGF-1 (e-IGF-1 group). The sham group did not receive any treatment with ACS or IGFs after surgery. Live μCT and histological analyses showed critical-sized bone defects in the sham group, whereas greater bone formation was observed in the p-IGF-1 and e-IGF-1 groups than the ACS group both 5 and 10weeks after surgery. Bone mineral density, bone volume, and bone surface values were also higher in the IGF groups than in the ACS group. Local delivery of p-IGF-1 or e-IGF-1 more greatly enhanced the expression of osteoblast-specific markers, but inhibited osteoclast formation, in newly formed bone compared with ACS control group. Specifically, p-IGF-1 treatment induced higher expression of alkaline phosphatase, osteocalcin, and osteopontin in the defect site than did e-IGF-1. Furthermore, treatment with p-IGF-1, but not e-IGF-1, increased mineralization of MC3T3-E1 cells, with the attendant upregulation of osteogenic marker genes. Collectively, our findings suggest the potential of p-IGF-1 in promoting the processes required for bone regeneration.

Efficiency to Discovery Transgenic Loci in GM Rice Using Next Generation Sequencing Whole Genome Re-sequencing

Molecular characterization technology in genetically modified organisms, in addition to how transgenic biotechnologies are developed now require full transparency to assess the risk to living modified and non-modified organisms. Next generation sequencing (NGS) methodology is suggested as an effective means in genome characterization and detection of transgenic insertion locations. In the present study, we applied NGS to insert transgenic loci, specifically the epidermal growth factor (EGF) in genetically modified rice cells. A total of 29.3 Gb (~72× coverage) was sequenced with a 2 × 150 bp paired end method by Illumina HiSeq2500, which was consecutively mapped to the rice genome and T-vector sequence. The compatible pairs of reads were successfully mapped to 10 loci on the rice chromosome and vector sequences were validated to the insertion location by polymerase chain reaction (PCR) amplification. The EGF transgenic site was confirmed only on chromosome 4 by PCR. Results of this study demonstrated the success of NGS data to characterize the rice genome. Bioinformatics analyses must be developed in association with NGS data to identify highly accurate transgenic sites.

Eckols reduce dental pulp inflammation through the ERK1/2 pathway independent of COX-2 inhibition

OBJECTIVES

The aim of this study was to elucidate the role of 6-6 bieckol (EB1) and pholorofucofuroeckol-A (EB5) from brown seaweed marine algae (Eisenia bicyclis) on lipopolysaccharide (LPS)-induced inflammation in human dental pulp cells (HDPCs).

METHODS

The cytotoxicity of EB1 and EB5 was examined by MTT assay on LPS-induced human dental pulp cells. Their role on expression of inflammatory, odontogenic, and osteogenic molecules was determined by Western blot analysis. The dentin mineralization was checked by alkaline phosphatase activity.

RESULTS

The five compounds from E. bicyclis have different structure with non-cytotoxic in HDPCs. EB1 and EB5 showed anti-inflammatory properties and inhibited phosphorylated-extracellular signal-regulated kinase (p-ERK1/2) and phosphorylated-c-jun N-terminal kinases (p-JNK) without any cytotoxicity. In particular, EB1 inhibited cyclooxygenase-2 (COX-2) and p-ERK1/2 signaling, and EB5 inhibited only p-ERK1/2 signaling but not COX-2. Both compounds inhibited nuclear factor kappa-B (NF-κB) translocation. Furthermore, EB1 and EB5 increased dentinogenic and osteogenic molecules, and dentin mineralized via alkaline phosphatase activity (ALP) in LPS-induced HDPCs.

CONCLUSIONS

This study elucidates that EB1 and EB5 have different types of anti-inflammatory property and help in dentin formation. Therefore, these compounds derived from marine algae of E. bicyclis may be used as selective therapeutic strategies for pulpitis and oral diseases.

Induction of immune responses in mice and pigs by oral administration of classical swine fever virus E2 protein expressed in rice calli

Classical swine fever (CSF), caused by the CSF virus (CSFV), is a highly contagious disease in pigs. In Korea, vaccination using a live-attenuated strain (LOM strain) has been used to control the disease. However, parenteral vaccination using a live-attenuated strain still faces a number of problems related to storage, cost, injection stress, and differentiation of CSFV infected and vaccinated pigs. Therefore, two kinds of new candidates for oral vaccination have been developed based on the translation of the E2 gene of the SW03 strain, which was isolated from an outbreak of CSF in 2002 in Korea, in transgenic rice calli (TRCs) from Oriza sativa L. cv. Dongjin to express a recombinant E2 protein (rE2-TRCs). The expression of the recombinant E2 protein (rE2) in rE2-TRCs was confirmed using Northern blot, SDS-PAGE, and Western blot analysis. Immune responses to the rE2-TRC in mice and pigs were investigated after oral administration. The administration of rE2-TRCs increased E2-specific antibodies titers and antibody-secreting cells when compared to animals receiving the vector alone (p < 0.05 and p < 0.01). In addition, mice receiving rE2-TRCs had a higher level of CD8+ lymphocytes and Th1 cytokine immune responses to purified rE2 (prE2) in vitro than the controls (p < 0.05 and p < 0.01). Pigs receiving rE2-TRCs also showed an increase in IL-8, CCL2, and the CD8+ subpopulation in response to stimulation with prE2. These results suggest that oral administration of rE2-TRCs can induce E2-specific immune responses.

Methylsulfonylmethane suppresses hepatic tumor development through activation of apoptosis

AIM: To investigate the effect of methylsulfonylmethane (MSM), recently reported to have anti-cancer effects, in liver cancer cells and transgenic mice.

METHODS: Three liver cancer cell lines, HepG2, Huh7-Mock and Huh7-H-ras^G12V, were used. Cell growth was measured by Cell Counting Kit-8 and soft agar assay. Western blot analysis was used to detect caspases, poly (ADP-ribose) polymerase (PARP), and B-cell lymphoma 2 (Bcl-2) expressions. For in vivo study, we administered MSM to H-ras^12V transgenic mice for 3 mo.

RESULTS: MSM decreased the growth of HepG2, Huh7-Mock and Huh7-H-ras^G12V cells in a dose-dependent manner. That was correlated with significantly increased apoptosis and reduced cell numbers in MSM treated cells. Cleaved caspase-8, cleaved caspase-3 and cleaved PARP were remarkably increased in the liver cancer cells treated with 500 mmol/L of MSM; however, Bcl-2 was slightly decreased in 500 mmol/L. Liver tumor development was greatly inhibited in the H-ras^12V transgenic mice treated with MSM, compared to control, by showing reduced tumor size and number. Cleaved PARP was significantly increased in non-tumor treated with MSM compared to control.

CONCLUSION: Liver injury was also significantly attenuated in the mice treated with MSM. Taken together, all the results suggest that MSM has anti-cancer effects through inducing apoptosis in liver cancer.

Production of recombinant human granulocyte macrophage-colony stimulating factor in rice cell suspension culture with a human-like N-glycan structure

The rice α-amylase 3D promoter system, which is activated under sucrose-starved conditions, has emerged as a useful system for producing recombinant proteins. However, using rice as the production system for therapeutic proteins requires modifications of the N-glycosylation pattern because of the potential immunogenicity of plant-specific sugar residues. In this study, glyco-engineered rice were generated as a production host for therapeutic glycoproteins, using RNA interference (RNAi) technology to down-regulate the endogenous α-1,3-fucosyltransferase (α-1,3-FucT) and β-1,2-xylosyltransferase (β-1,2-XylT) genes. N-linked glycans from the RNAi lines were identified, and their structures were compared with those isolated from a wild-type cell suspension. The inverted-repeat chimeric RNA silencing construct of α-1,3-fucosyltransferase and β-1,2-xylosyltransferase (Δ3FT/XT)-9 glyco-engineered line with significantly reduced core α-1,3-fucosylated and/or β-1,2-xylosylated glycan structures was established. Moreover, levels of plant-specific α-1,3-fucose and/or β-1,2-xylose residues incorporated into recombinant human granulocyte/macrophage colony-stimulating factor (hGM-CSF) produced from the N44 + Δ3FT/XT-4 glyco-engineered line co-expressing ihpRNA of Δ3FT/XT and hGM-CSF were significantly decreased compared with those in the previously reported N44-08 transgenic line expressing hGM-CSF. None of the glyco-engineered lines differed from the wild type with respect to cell division, proliferation or ability to secrete proteins into the culture medium.

Antibacterial activity of phytochemicals isolated from Atractylodes japonica against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has been emerging worldwide as one of the most important problems in communities and hospitals. Therefore, new agents are needed to treat acute oral infections from MRSA. In this study, antibacterial compounds from the roots of Atractylodes japonica (A. japonica) were isolated and characterized. The compounds were isolated from the root extracts using HPLC-piloted activity-guided fractionations. Four A. japonica compounds were isolated and identified as atractylenolide III (1), atractylenolide I (2), diacetylatractylodiol [(6E,12E)-tetradeca-6,12-diene-8,10-diyne-1,3-diol diacetate, TDEYA, 3). and (6E,12E)-tetradecadiene-8,10-diyne-1,3-diol (TDEA, 4), which was obtained by hydrolysis of TDEYA. The minimum inhibitory concentrations (MICs) was determined in the setting of clinical MRSA isolates. Compound 4 showed anti-MRSA activity with a MIC value of 4-32 μg/mL. The overall results provide promising baseline information for the potential use of the extract of A. japonica as well as some of the isolated compounds in the treatment of bacterial infections.

Endovascular coil embolization of aneurysms with a branch incorporated into the sac

BACKGROUND AND PURPOSE

Because of the concern for occlusion of the incorporated branch artery, an aneurysm with a branch incorporated into the sac has been regarded as a contraindication for coiling. The aim of this study is to evaluate the feasibility, techniques, and clinical and angiographic outcomes of coiling for aneurysms with a branch incorporated into the sac.

MATERIALS AND METHODS

The medical records and radiologic studies of 69 patients with 79 aneurysms having a branch incorporated into the sac (26 ruptured, 53 unruptured) were retrospectively reviewed and evaluated.

RESULTS

Coiling was accomplished in 78 aneurysms in 68 patients but was suspended in 1 due to incorporated branch occlusion. The aneurysms were treated by using the following techniques: single-catheter (n = 37), multicatheter (n = 22), balloon-remodeling (n = 7), stent-assisted coiling (n = 6), and combined (n = 7). Postembolization angiography revealed the following: near-complete occlusion in 71 (89.8%), remnant neck in 4 (5.1%), and incomplete occlusion in 4 (5.1%) aneurysms. Procedure-related permanent morbidity and mortality rates were 5.8% (4/69) and 0%, respectively. All patients with unruptured aneurysms had a modified Rankin Scale (mRS) score of 0, except for 1 patient who had an mRS score of 3. Of the 26 patients with ruptured aneurysms, 18 had favorable outcome (mRS 0-2) but 8 had poor outcome (mRS 3-6). Follow-up angiography was available at least once at 6-50 months (mean, 15 months) in 55 aneurysms (69.6%), of which 45 showed stable or improved occlusion; 4, minor recurrences; and 6, major recurrences. All 6 major recurrent aneurysms were retreated without complication by using a single-catheter (n = 1), multicatheter (n = 2), or balloon-assisted technique (n = 3).

CONCLUSIONS

With appropriate techniques, most aneurysms with a branch incorporated into the sac could be safely treated by coiling, with acceptable outcomes.

Effect of cytoplasmic lipid content on in vitro developmental efficiency of bovine IVP embryos

The objective was to evaluate the effect of cytoplasmic lipid content on the embryonic developmental efficiency of bovine in vitro embryo production (IVP) embryos. Ovaries from Korean native cows (Bos taurus coreanae) were collected from a local abattoir, and cumulus-oocyte complexes (COCs) were recovered from follicles 2 to 8mm in diameter. The oocytes were divided into three groups, dependent on their cytoplasm color: pale color (PC), brown color (BC), and dark color (DC). The COCs were fertilized using frozen-thawed semen from a single Hanwoo bull. Based on measurement of the cytoplasmic color intensity of oocytes after 22h of in vitro maturation (IVM), the DC group had lower (P<0.05) color intensity than that in the BC and PC groups (56.3+/-2.7, 93.3+/-5.1, and 123.9+/-12.0, respectively). Based on MitoTracker Green FM staining, the number of mitochondria in the DC (170.1+/-31.2) group was significantly higher than that in the BC (137.5+/-30.8) and PC (105.5+/-25.3) groups. The cleavage rate in the DC (81.5%) group was also higher than that in the PC (50.4%) group (P<0.05), as was the development rate to blastocyst stage (18.9% vs. 9.8%). Finally, cell numbers of blastocysts in the DC (150.8+/-28.0) group were higher (P<0.05) than that in the BC (107.6+/-17.8) and PC (80.5+/-12.3) groups. In conclusion, cytoplasm color was a useful selection parameter for abattoir-derived oocytes destined for IVP.

Tumor targeting of humanized fragment antibody secreted from transgenic rice cell suspension culture

The tumor-associated glycoprotein 72 (TAG 72) has been shown to be expressed in the majority of human adenocarcinomas. In an effort to develop a technique for the safe and inexpensive production of large quantities of anti-TAG 72 humanized antibody fragments (hzAb) as a future source of clinical-grade proteins, we developed a transgenic rice cell suspension culture system. The in vivo assembly and secretion of hzAb were achieved in a transgenic rice cell culture under the control of the rice alpha amylase 3D (RAmy 3D) expression system, and the biological activities of plant-derived hzAb were determined to be quite similar to those of animal-derived antibody. Purified hzAb was shown to bind to the recombinant antigen, TAG 72, and to bind specifically to human LS 174T colon adenocarcinoma cells expressing the TAG 72 antigen, and this binding occurred to the same extent as was seen with animal-derived antibody. Plant-derived hzAb proved as effective as animal-derived antibody in targeting tumors of xenotransplanted LS 174T cells in nude mice. The results of this study indicate that the hzAb derived from plant cell suspension cultures may have great potential for pharmaceutical applications in the development of future cancer therapeutic and diagnostic protocols.

Amylase gene silencing by RNA interference improves recombinant hGM-CSF production in rice suspension culture

A rice cell suspension culture system with the Ramy3D promoter, which is induced by sucrose starvation, has been previously utilized to produce large quantities of recombinant proteins. Although this expression system was reported previously to generate a good yield of recombinant hGM-CSF in transgenic rice cell suspension culture, rice alpha-amylase was a dominant protein, with 43% of total secreted proteins and an obstacle to the production and purification of secreted recombinant proteins in a rice cell suspension culture. In this study, an intron-containing self-complementary hairpin RNA (ihpRNA)-mediated post transcriptional gene silencing (PTGS) strategy for the rice alpha-amylase gene was applied in order to overcome this problem in rice cell suspension culture systems. The reduction of the mRNA level of the rice alpha-amylase gene was verified via Northern blot analysis and siRNA, an initiator of RNA interference, was detected via an RNase protection assay. The amount of rice alpha-amylase in the culture medium was reduced to 8.2% as compared to that of the wild-type. A transgenic rice cell suspension culture expressing both the hGM-CSF and ihpRNA of the rice alpha-amylase gene demonstrated that the quantity of rice alpha-amylase was reduced to 22% and that the accumulation of hGM-CSF increased by 1.9-fold as compared to that in the transgenic cell line expressing hGM-CSF only. These results indicated that RNAi technology should be of great utility for suppressing undesirable genes, and should improve accumulation and facilitate the purification of secreted recombinant proteins in rice cell suspension cultures.

Co-expression of proteinase inhibitor enhances recombinant human granulocyte-macrophage colony stimulating factor production in transgenic rice cell suspension culture

The synthetic gene (sPI-II) harboring the chymotrypsin (C1) and trypsin (T1) inhibitor domains of the Nicotiana alata serine proteinase inhibitor II gene has been previously expressed, and extracellular protease activity was shown to be reduced in the suspension culture medium. In this study, the sPI-II gene was introduced into transgenic rice cells expressing rhGM-CSF (recombinant human granulocyte-macrophage colony-stimulating factor), in an effort to reduce protease activity and increase rhGM-CSF accumulation in the suspension culture medium. The integration and expression of the introduced sPI-II gene in the transgenic rice cells were verified via genomic DNA PCR amplification and Northern blot analysis, respectively. Relative protease activity was found to have been reduced and rhGM-CSF production was increased 2-fold in the co-transformed cell suspension culture with rhGM-CSF and the sPI-II gene, as compared with that observed in the transformed cell suspension culture expressing rhGM-CSF only. These results indicate that a transformed plant cell suspension culture system expressing the proteinase inhibitor can be a useful tool for increasing recombinant protein production.

Improvement of recombinant hGM-CSF production by suppression of cysteine proteinase gene expression using RNA interference in a transgenic rice culture

Recombinant proteins have been previously synthesized in a transgenic rice cell suspension culture system with the rice amylase 3D promoter, which can be induced via sugar starvation. However, the secreted recombinant proteins have been shown to be rapidly decreased as the result of proteolytic degradation occurring during prolonged incubation. The secreted proteases were identified via two-dimensional electrophoresis (2-DE) and ESI/Q-TOF mass spectrometry analyses. The internal amino acid sequences of 8 of 37 spots corresponded to cysteine proteinase (CysP), which is encoded for by Rep1 and EP3A. This result shows that CysP is a major secreted protease in rice cell suspension cultures following induction via sugar starvation. Intron-containing self-complementary hairpin RNA (ihpRNA)-mediated post-transcriptional gene silencing (PTGS) was applied to suppress the expression of CysP in rice cell suspension cultures. The reduction of rice CysP mRNA and the detection of siRNA specific to CysP, an initiator of RNAi, were verified via Northern blot analysis and RNase protection assays, respectively, thereby indicating that PTGS operated successfully in this system. The analysis of total secreted protease and CysP activities evidenced lower activity than was observed with the wild-type. Furthermore, suspension cultures of rice cells transformed with both hGM-CSF and the gene expressing the ihpRNA of CysP evidenced a reduction in total protease and CysP activities, and an up to 1.9-fold improvement in hGM-CSF production as compared to that observed in a rice cell line expressing hGM-CSF only. These results demonstrate the feasibility of the suppression of CysP via RNA interference to reduce protease activity and to increase target protein accumulation in rice cell suspension cultures.

Expression of human growth hormone in transgenic rice cell suspension culture

Human growth hormone (hGH), a pituitary-derived polypeptide, evidences a wide range of biological functions, including protein synthesis, cell proliferation, and metabolism. A synthetic hGH gene (shGH) has been synthesized on the basis of plant-optimized codon usage via an overlap PCR strategy and located in a plant expression vector under the control of the rice amylase 3D (Ramy3D) promoter, which is induced by sugar starvation. The plant expression vector was introduced into rice calli (Oryza sativa L. cv. Donjin) via particle bombardment transformation methods. The integration of the shGH gene into the chromosome of the transgenic rice callus was verified via genomic DNA PCR amplification and shGH expression in transgenic rice suspension cells was confirmed via Northern blot analysis. The shGH protein was detected in the transgenic rice cell suspension culture medium following induction with sugar starvation, using Western blot analysis. The quantity of shGH that accumulated in the transgenic rice cell suspension medium was 57 mg/l. The shGH accumulated in the transgenic rice cell suspension culture medium evidenced a biological activity similar to that of Escherichia coli-derived recombinant hGH. These results indicate that the shGH was generated and accumulated in the transgenic rice cell suspension culture medium, and manifested biological activity.

Production of an anti-mouse MHC class II monoclonal antibody with biological activity in transgenic tobacco

To produce a monoclonal antibody specific to a mouse major histocompatibility complex (MHC) class II protein, we synthesized the complementary DNAs for the heavy and light chains of a monoclonal antibody by PCR amplification. These cDNAs were then introduced separately into tobacco plant cells. After performing Northern blot analysis to confirm the expression of each of the chain genes in the transformed plants, we constructed transgenic plants expressing both the heavy and light chains by sexual crossing. The expression of the heavy and light chain genes in the sexually crossed plant was confirmed by Northern and Western blot analyses, respectively. Fluorocytometric analysis showed that the plant-derived antibodies, which we purified using a protein G affinity column, bound specifically to target cells that expressed the cognate MHC class II molecules on their cell surfaces. The results of this study demonstrate that a monoclonal antibody against mouse MHC class II proteins can be expressed in transgenic plants. They also show the specific binding activity of plant-derived antibodies to cognate antigens.

Reduced protease activity in transformed rice cell suspension cultures expressing a proteinase inhibitor

In this study, we synthesized a synthetic serine proteinase inhibitor II gene (sPI-II) that harbored the chymotrypsin and trypsin inhibitor domains of the PI-II gene from Nicotiana alata. In an effort to reduce protease activity in a rice cell suspension culture, we first synthesized sPI-II using overlap PCR and then introduced the gene into a rice calli (Oryza sativa L. cv. Dongin) by particle bombardment-mediated transformation. The sPI-II gene was under the control of a rice alpha-amylase 3D promoter induced by sugar starvation. To verify the integration and expression of the sPI-II gene in the transformed rice cells, we employed genomic DNA PCR amplification and Northern blot analysis, respectively. The relative protease activity of the transformed cell suspension culture was reduced to approximately 23% when compared to the non-transformed culture. This indicates that a transformed suspension culture system expressing a proteinase inhibitor, may be a useful tool to protect against recombinant protein losses resulting from extracellular proteases.

Production and characterization of human CTLA4Ig expressed in transgenic rice cell suspension cultures

Human cytotoxic T-lymphocyte antigen 4-immunoglobulin (hCTLA4I g) fusion protein, a novel immunosuppressive agent, was expressed in transgenic rice cell suspension culture and its characteristics and in vitro activities were investigated. The expression vector pMYN409 was constructed to express hCTLA4I g under the control of rice alpha-amylase 3D (RAmy3D) promoter. Transgenic calli were prepared by particle bombardment mediated transformation and were screened for hCTLA4I g expression using ELISA. Under the induction condition by sugar starvation, suspension-cultured rice cells secreted hCTLA4I g into the media up to 31.4 mg/L in flask culture. The rice-derived hCTLA4Ig (hCTLA4IgP) was purified from the culture media with affinity chromatography using protein A and compared with CHO-derived hCTLA4Ig (hCTLA4IgM). Recombinant hCTLA4IgP has molecular weight of approximately 50 kDa on SDS-PAGE under reducing condition, which is a little different from that of hCTLA4IgM probably due to the difference of carbohydrate chain structures. Purified hCTLA4IgP was biologically active and was confirmed to suppress T-cell proliferation.

Production of bioactive human granulocyte-colony stimulating factor in transgenic rice cell suspension cultures

Human granulocyte-colony stimulating factor (hG-CSF), a human cytokine, was expressed in transgenic rice cell suspension culture. The hG-CSF gene was cloned into the rice expression vector containing the promoter, signal peptide, and terminator derived from a rice alpha-amylase gene Amy3D. Using particle bombardment-mediated transformation, hG-CSF gene was introduced into the calli of rice (Oryza sativa) cultivar Dong-jin. Expression of the hG-CSF gene was confirmed by ELISA and Northern blot analysis. The amount of recombinant hG-CSF accumulated in culture medium from transgenic rice cell suspension culture on the sugar starvation was determined by time series ELISA. Biological activity of the plant derived hG-CSF was confirmed by measuring the proliferation of the AML-193 cells, and was similar to that of the commercial Escherichia coli-derived hG-CSF. In this paper, we discuss the attractive attributes of using rice cell suspension system for the expression of therapeutic recombinant hG-CSF.

High-level expression of the neutralizing epitope of porcine epidemic diarrhea virus by a tobacco mosaic virus-based vector

Porcine epidemic diarrhea virus (PEDV) causes acute enteritis in pigs of all ages and is often fatal for neonates. A tobacco mosaic virus (TMV)-based vector was utilized for the expression of a core neutralizing epitope of PEDV (COE) for the development of a plant-based vaccine. In this study, the coding sequence of a COE gene was optimized based on the modification of codon usage in tobacco plant genes and the removal of mRNA-destabilizing sequences. The native and synthetic COE genes were cloned into TMV-based vectors and expressed in tobacco plants. The recombinant COE protein constituted up to 5.0% of the total soluble protein in the leaves of tobacco plants infected with the TMV-based vector containing synthetic COE gene, which was approximately 30-fold higher than that in tobacco plants infected with TMV-based vector containing a native COE gene. Therefore, this result indicates that the plant viral expression system with a synthetic gene optimized for plant expression is suitable to produce a large amount of antigen for the development of plant-based vaccine rapidly.

Production and secretion of biologically active human granulocyte-macrophage colony stimulating factor in transgenic tomato suspension cultures

A complementary DNA encoding human granulocyte-macrophage colony stimulating factor (hGM-CSF) was cloned and introduced into tomato (Lycopersicon esculentum cv. Seokwang) using Agrobacterium-mediated transformation. Genomic PCR and Northern blot analysis demonstrated the integration of the construction into the plant nuclear genome and expression of the hGM-CSF in transgenic tomato. The cell suspension culture was established from leaf-derived calli of the transgenic tomato plants transformed with the hGM-CSF gene. Recombinant hGM-CSF was synthesized by the transgenic cell culture and secreted into the growth medium at 45 microg l(-1) after 10 d' cultivation.

Comparing constitutive promoters using CAT activity in transgenic tobacco plants

The effectiveness of different promoters for use in transgenic tobacco was compared using a reporter gene expressing chloramphenicol acetyl transferase (CAT). Plasmids with CAT gene controlled by cauliflower mosaic virus 35S (CaMV 35S), rice actin1 (Ract1) and tobacco polyubiquitin (Tubi.u4) promoters were delivered into tobacco plants by Agrobacterium-mediated transformation. The Ract1 promoter, previously shown to be a strong promoter in rice and other monocots, failed to promote strong expression in tobacco. CAT expression was greatest from the vector carrying Tubi.u4 with a 5'UTR and leader intron without a ubiquitin monomer. In transgenic plants harboring the Tubi.u4 promoter, CAT expression was approximately twice that of the CaMV 35S promoter. Our results suggest that foreign genes under the control of a ubiquitin promoter devoid of monomer will be useful for high-level gene expression in tobacco.

High level of expression of recombinant human granulocyte-macrophage colony stimulating factor in transgenic rice cell suspension culture

Recombinant human granulocyte-macrophage colony stimulating factor (hGM-CSF) has been previously produced in tobacco cell suspension cultures. However, the amount of hGM-CSF accumulated in the culture medium dropped quickly from its maximum of 150 microg/L at 5 d after incubation. To overcome this problem, we sought an expression system in which heterologous gene expression could be induced at high levels. We selected a rice amylase expression system in which the promoter Ramy3D is induced to express recombinant protein by sucrose starvation. This induction system was found to give good yield of recombinant hGM-CSF in transgenic rice cell suspension culture and protease activity of this culture medium was low compared to that of tobacco culture system.

Expression and secretion of the heterodimeric protein interleukin-12 in plant cell suspension culture

It has been suggested that plant cell culture is the most suitable system for producing small-to-medium quantities of specialized, expensive, and high-purity proteins. Here, we report that a heterodimeric protein, human interleukin-12 (hIL-12), was expressed and secreted into culture medium in a biologically active form. A transgenic plant expressing hIL-12 was constructed by sexual crossing of plants that expressed each subunit of the protein. From a piece of transgenic plant, callus was induced and cell suspension culture was established. The biological activity and amount of hIL-12 secreted into culture medium were analyzed using bioassays and ELISA. Analysis of cellular localization demonstrated that the protein was secreted into the culture medium together with its intrinsic signal peptide.

Increased production of human granulocyte-macrophage colony stimulating factor (hGM-CSF) by the addition of stabilizing polymer in plant suspension cultures

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein that stimulates the production of granulocytes, macrophages, and white blood cells. Secretion of human GM-CSF from cell suspension cultures of genetically modified tobacco has been facilitated using natural mammalian leader sequences. At the mid-exponential growth phase (day 4 after the initiation of cell suspension culture), GM-CSF was detected in the medium at a maximum concentration of 180 microg l(-1). However, the secreted GM-CSF was unstable in the medium, and rapidly degraded after day 5. In order to stabilize the secreted GM-CSF, three stabilizing polymers were tested, polyethylene glycol, polyvinylpyrrolidone and gelatin. Gelatin was the most effective in stabilizing the secreted GM-CSF. Following the addition of 5% (w/v) gelatin, the maximum GM-CSF concentration reached 783 microg l(-1), a 4.6-fold increase over control.

Immunolocalization of aquaporin-8 in rat kidney, gastrointestinal tract, testis, and airways

The purpose of this study was to determine the cellular and subcellular localization of aquaporin-8 (AQP8) in rat kidney and other organs by RT-PCR analyses and by immunoblotting and immunohistochemistry using peptide-derived rabbit antibodies to rat AQP8. RT-PCR and Southern blotting revealed the presence of AQP8 mRNA in all kidney zones. LLC-PK(1) cells transfected with a rat AQP8 construct exhibited strong labeling with the affinity-purified antibodies, whereas controls using cells transfected with the vector, but without the insert, were negative. The labeling was almost exclusively associated with intracellular vesicles. Immunoblotting of kidney membrane fractions revealed a predominant single band of 26-28 kDa. AQP8 immunoreactivity was mainly present in the cortex and outer stripe of the outer medulla. Sequential ultracentrifugation of rat kidney membrane revealed that AQP8 resides predominantly in intracellular vesicular fractions. Immunocytochemistry revealed modest labeling of proximal tubules and weak labeling of collecting ducts in cortex and medulla of rat kidney. The labeling was confined to cytoplasmic areas with no labeling of the brush border. Immunoblotting and RT-PCR/Southern blotting also revealed the presence of AQP8 protein and mRNA in rat liver, testis, epididymis, duodenum, jejunum, colon, and bronchi/trachea. Consistent with this, immunohistochemistry revealed AQP8 labeling in the hepatocytes and spermatogenic cells in testis and in the basal cells in ductus epididymis, trachea, and bronchial epithelia. Moreover, AQP8 labeling was observed in the myoepithelial cells in salivary, bronchial, and tracheal glands with no labeling of acini or ductal epithelial cells. AQP8 is also present in the surface epithelial cells in duodenum, jejunum, and colon. In conclusion, AQP8 is expressed at low levels in rat kidney proximal tubules and collecting ducts, and it is present in distinct cell types in liver, testis, epididymis, duodenum, jejunum, colon, trachea, and principal bronchi as well as in multiple glands, including salivary glands.

Accumulation of intraventricular fat in an intracranial epidermoid tumor: case report

OBJECTIVE AND IMPORTANCE

A fat component within the ventricles or subarachnoid space in fat-containing tumors such as an epidermoid or a dermoid has been observed in rare instances. However, there have been no reports regarding an increase in the size of such a fat component. We describe the case of an epidermoid tumor with intraventricular fat that showed an increase in size and amount.

CLINICAL PRESENTATION

A 26-year-old woman was admitted with headache and diplopia. Computed tomography and magnetic resonance imaging of the brain revealed a fat-containing suprasellar tumor and widespread fat globules in adjacent sulci and cisterns and within the frontal horn of the lateral ventricle.

INTERVENTION

The patient underwent a pterional craniotomy. Removal of the suprasellar tumor was nearly total. Histopathological examination revealed an epidermoid tumor. Sequential magnetic resonance imaging throughout the ensuing 65-month period revealed no evidence of tumor recurrence; however, the intraventricular fat remained and increased in size. The patient underwent surgery via the transcallosal approach at 69 months after the initial operation, and the presence of free-floating oily fat globules was confirmed.

CONCLUSION

In the case of a fat-containing tumor with free fat in the cerebrospinal fluid spaces, careful serial examination is necessary, with particular attention to the possibility of changes in size.

The renal thiazide-sensitive Na-Cl cotransporter as mediator of the aldosterone-escape phenomenon

The kidneys "escape" from the Na-retaining effects of aldosterone when circulating levels of aldosterone are inappropriately elevated in the setting of normal or expanded extracellular fluid volume, e.g., in primary aldosteronism. Using a targeted proteomics approach, we screened renal protein extracts with rabbit polyclonal antibodies directed to each of the major Na transporters expressed along the nephron to determine whether escape from aldosterone-mediated Na retention is associated with decreased abundance of one or more of renal Na transporters. The analysis revealed that the renal abundance of the thiazide-sensitive Na-Cl cotransporter (NCC) was profoundly and selectively decreased. None of the other apical solute-coupled Na transporters displayed decreases in abundance, nor were the total abundances of the three ENaC subunits significantly altered. Immunocytochemistry showed a strong decrease in NCC labeling in distal convoluted tubules of aldosterone-escape rats with no change in the cellular distribution of NCC. Ribonuclease protection assays (RPAs) revealed that the decrease in NCC protein abundance was not associated with altered NCC mRNA abundance. Thus, the thiazide-sensitive Na-Cl cotransporter of the distal convoluted tubule appears to be the chief molecular target for regulatory processes responsible for mineralocorticoid escape, decreasing in abundance via a posttranscriptional mechanism.

Identification and localization of aquaporin water channels in human salivary glands

Aquaporin (AQP) water channels are expressed in a variety of fluid-transporting epithelia and are likely to play a significant role in salivary secretion. Our aim was to identify and localize the aquaporins expressed in human salivary glands. Total RNA was extracted from human parotid, submandibular, sublingual, and labial glands and from human brain. Expression of aquaporin mRNA was assessed by RT-PCR using specific primers for human AQP1, AQP3, AQP4, and AQP5. All four aquaporins were detected by RT-PCR in all of the glands, and the sequences were confirmed after further amplification with nested primers. Cleaned PCR products were then used as (32)P-labeled cDNA probes in a semiquantitative Northern blot analysis using glyceraldehyde-3-phosphate dehydrogenase as reference. Only AQP1, AQP3, and AQP5 mRNAs were present at significant levels. AQP localization was determined by immunohistochemistry on paraffin sections using affinity-purified primary antibodies and peroxidase-linked secondary antibodies. Each salivary gland type showed a broadly similar staining pattern: AQP1 was localized to the capillary endothelium and myoepithelial cells; AQP3 was present in the basolateral membranes of both mucous and serous acinar cells; AQP4 was not detected; and AQP5 was expressed in the luminal and canalicular membranes of both types of acinar cell. We conclude that AQP3 and AQP5 together may provide a pathway for transcellular osmotic water flow in the formation of the primary saliva.

Downregulation of AQP1, -2, and -3 after ureteral obstruction is associated with a long-term urine-concentrating defect

Previously, we demonstrated that 24 h of bilateral ureteral obstruction (BUO) and short-term release of BUO was associated with a decrease in the expression of aquaporin-2 (AQP2), polyuria, and a reduced urinary concentrating capacity (10). The purposes of the present study were to examine whether BUO and the long-term release of BUO (BUO-R) for 3, 14, and 30 days were associated with changes in the expression of renal AQP1, AQP2, and AQP3 and whether such changes were associated with parallel changes in urinary output and urinary concentrating capacity. Rats (n = 4-7 in each group) were kept in metabolic cages for measurements of urinary output. Kidneys were removed to determine the expression levels of AQP1, AQP2, and AQP3 by semiquantitative immunoblotting. AQP2 was downregulated after 24 h of BUO (42 +/- 3%). Downregulation of AQP2 persisted 3 (43 +/- 14%; P < 0.01) and 15 days after BUO-R (48 +/- 11%; P < 0.01) but was normalized 30 days after BUO-R. AQP3 showed a similar pattern. Moreover, AQP1 was downregulated in response to BUO (65 +/- 7%) and remained downregulated 3 days after BUO-R (41 +/- 5%), 14 days after BUO-R (57 +/- 8%), and 30 days after BUO-R (59 +/- 5%). BUO-R resulted in a significant polyuria that gradually decreased, although it remained significant at day 30. Urinary concentrating capacity remained significantly impaired when determined 3, 14, and 30 days after BUO-R in response to a 24-h period of thirst (1,712 +/- 270 vs. 2,880 +/- 91 mosmol/kgH2O at day 30, P < 0.05). In conclusion, the expression of AQP1, AQP2, and AQP3 were long-term downregulated after BUO-R, suggesting that dysregulation of aquaporins located at the proximal tubule, thin descending limb of the loop of Henle, and the collecting duct may contribute to the long-term polyuria and impairment of urinary concentrating capacity associated with obstructive nephropathy.

Altered expression of renal aquaporins and Na+ transporters in rats treated with L-type calcium blocker

Nifedipine, a calcium antagonist, has diuretic and natriuretic properties. However, the molecular mechanisms by which these effects are produced are poorly understood. We examined kidney abundance of aquaporins (AQP1, AQP2, and AQP3) and major sodium transporters [type 3 Na/H exchanger (NHE-3); type 2 Na-Pi cotransporter (NaPi-2); Na-K-ATPase; type 1 bumetanide-sensitive cotransporter (BSC-1); and thiazide-sensitive Na-Cl cotransporter (TSC)] as well as inner medullary abundance of AQP2, phosphorylated-AQP2 (p-AQP2), AQP3, and calcium-sensing receptor (CaR). Rats treated with nifedipine orally (700 mg/kg) for 19 days had a significant increase in urine output, whereas urinary osmolality and solute-free water reabsorption were markedly reduced. Consistent with this, immunoblotting revealed a significant decrease in the abundance of whole kidney AQP2 (47 ± 7% of control rats, P< 0.05) and in inner medullary AQP2 (60 ± 7%) as well as in p-AQP2 abundance (17 ± 6%) in nifedipine-treated rats. In contrast, whole kidney AQP3 abundance was significantly increased (219 ± 28%). Of potential importance in modulating AQP2 levels, the abundance of CaR in the inner medulla was significantly increased (295 ± 25%) in nifedipine-treated rats. Nifedipine treatment was also associated with increased urinary sodium excretion. Consistent with this, semiquantitative immunoblotting revealed significant reductions in the abundance of proximal tubule Na+ transporters: NHE-3 (3 ± 1%), NaPi-2 (53 ± 12%), and Na-K-ATPase (74 ± 5%). In contrast, the abundance of the distal tubule Na-Cl cotransporter (TSC) was markedly increased (240 ± 29%), whereas BSC-1 in the thick ascending limb was not altered. In conclusion, 1) increased urine output and reduced urinary concentration in nifedipine-treated-rats may, in part, be due to downregulation of AQP2 and p-AQP2 levels; 2) CaR might be involved in the regulation of water reabsorption in the inner medulla collecting duct; 3) reduced expression of proximal tubule Na+ transporters (NHE-3, NaPi-2, and Na, K-ATPase) may be involved in the increased urinary sodium excretion; and 4) increase in TSC expression may occur as a compensatory mechanism.

Immunocytochemical and immunoelectron microscopic localization of α-, β-, and γ-ENaC in rat kidney

Epithelial sodium channel (ENaC) subunit (α, β, and γ) mRNA and protein have been localized to the principal cells of the connecting tubule (CNT), cortical collecting duct (CCD), and outer medullary collecting duct (OMCD) in rat kidney. However, the subcellular localization of ENaC subunits in the principal cells of these cells is undefined. The cellular and subcellular localization of ENaC subunits in rat kidney was therefore examined. Immunocytochemistry demonstrated the presence of all three subunits in principal cells of the CNT, CCD, OMCD, and IMCD. In cortex and outer medulla, confocal microscopy demonstrated a difference in the subcellular localization of subunits. α-ENaC was localized mainly in a zone in the apical domains, whereas β- and γ-ENaC were found throughout the cytoplasm. Immunoelectron microscopy confirmed the presence of ENaC subunits in both the apical plasma membrane and intracellular vesicles. In contrast to the labeling pattern seen in cortex, α-ENaC labeling in IMCD cells was distributed throughout the cytoplasm. In the urothelium covering pelvis, ureters, and bladder, immunoperoxidase and confocal microscopy revealed differences the presence of all ENaC subunits. As seen in CCD, α-ENaC was present in a narrow zone near the apical plasma membrane, whereas β- and γ-ENaC were dispersed throughout the cytoplasm. In conclusion, all three subunits of ENaC are expressed throughout the collecting duct (CD), including the IMCD as well as in the urothelium. The intracellular vesicular pool in CD principal cells suggests ENaC trafficking as a potential mechanism for the regulation of Na+ reabsorption.