Advanced Glycation End Product Accumulation Is Associated With Low Skeletal Muscle Mass, Weak Muscle Strength, and Reduced Bone Density: The Nagahama Study

BACKGROUND

The accumulation of advanced glycation end product (AGE) might exert deleterious effects on musculoskeletal properties. Our study aims to clarify this possible association in a large general population.

METHODS

This study investigated a general population of 9,203 patients (mean age, 57.8 years). Skeletal muscle mass was measured by bioelectrical impedance analysis, whereas accumulation of AGEs was assessed by skin autofluorescence (SAF-AGE). The muscle strength of upper and lower limbs and usual gait speed were measured in a portion of older (≥60 years of age) participants (n = 1,934). The speed of sound (SOS) in the calcaneal bone was assessed via a quantitative ultrasound technique.

RESULTS

In the total population, the frequency of low skeletal muscle mass linearly increased with the SAF-AGE quartiles (Q1: 14.2%, Q2: 16.1%, Q3: 21.1%, Q4: 24.8%; p < .001), and this association was independent of covariates including glycemic traits (Q4: odds ratio [OR] = 1.48, p < .001). The association between the highest SAF-AGE quartile and low skeletal muscle mass remained significant in the older subpopulation (OR = 1.85, p = .002). A similar but weak association was observed for low SOS (Q1: 8.9%, Q2: 8.3%, Q3: 10.4%, Q4: 12.2%; p < .001). Similar inverse associations were also observed with grip strength (OR = 1.98, p = .003), hip flexion strength (OR = 1.50, p = .012), and hip abduction strength (OR = 1.78, p = .001), but not with usual gait speed.

CONCLUSION

Accumulation of AGEs might be a deleterious factor for musculoskeletal properties.

P4660Lipoprotein particle profiles compared with standard lipids in the association with sub-clinical aortic valve calcification in apparently healthy Japanese men

Introduction

Calcific aortic valve disease (CAVD) is one of the most common heart diseases worldwide, and its prevalence has increased in developed countries along with aging populations. Subclinical CAVD is characterized by aortic valve calcification (AVC) that may lead to aortic stenosis. AVC shares the same risk factors with atherosclerotic disease. Recently, nuclear magnetic resonance (NMR)-based lipoprotein particles, low-density and high-density lipoprotein particles (LDL-p, HDL-p) in particular, have emerged as novel markers of atherosclerotic disease. It has been unclear, however, whether NMR-based particles are associated with AVC.

Purpose

To examine cross-sectional association of NMR-based lipoprotein particles, standard lipids with AVC, and compare their strengths of association.

Methods

We studied a community-based random sample of Japanese men aged 40–79 years examined in 2006–08 in Japan. We excluded participants with history of myocardial infarction, stroke, aortic valve surgery, serum triglyceride concentration ≥400 mg/dl, estimated glomerular filtration rate (eGFR) <30 (ml/min/1.73m2), and use of lipid-lowering medication. We scored the degree of AVC according to Agatston's method, and defined prevalent AVC as the score >0. Lipoprotein particles were measured using NMR spectroscopy.

In our main analysis, we obtained multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (95% CI) of prevalent AVC in the top quartile (Q4) for each lipid index in reference to the lowest quartile (Q1). Adjusting covariates include age, smoking, drinking, systolic blood pressure, glycated hemoglobin, medications for hypertension and/or for diabetes, eGFR, C-reactive protein. For sensitivity analysis, we repeated similar analyses presenting ORs per 1 standard deviation (SD) higher NMR-lipoproteins particles or standard lipids.

Results

Of 874 participants we analyzed, 153 (17.5%) men had AVC. The average (SD) age was 63.3 (10.0) years. Those with AVC tended to be older, likely to have clustering of atherosclerotic risk factors. Multivariable-adjusted ORs of prevalent AVC for Q4 versus Q1 were significantly positive for LDL-p [OR, 2.21 (95% CI: 1.24, 3.95] and low-density lipoprotein cholesterol (LDL-c) [2.17 (1.24, 3.80)]. In contrast, neither HDL-p nor high-density lipoprotein cholesterol (HDL-c) was significantly associated with AVC. In sensitivity analyses, however, the corresponding ORs per 1SD higher lipids/lipoprotein particles were smaller in LDL-p [1.33 (1.09, 1.63)] than LDL-c [1.41 (1.15, 1.73)]. The association of HDL-p became significant [1.28 (1.02, 1.61)] (per 1SD decrement) in the sensitivity analysis.

Conclusion

The overall associations of AVC with NMR-based lipoprotein particles (i.e. LDL-p, HDL-p) are comparable to those of standard lipids. This finding is parallel to the association between atherosclerotic cardiovascular diseases with NMR-based lipoproteins.

Engineering a bispecific antibody with a common light chain: Identification and optimization of an anti-CD3 epsilon and anti-GPC3 bispecific antibody, ERY974

The antibody drug market is rapidly expanding, and various antibody engineering technologies are being developed to create antibodies that can provide better benefit to patients. Although bispecific antibody drugs have been researched for more than 30 years, currently only a limited number of bispecific antibodies have achieved regulatory approval. Of the few successful examples of industrially manufacturing a bispecific antibody, the "common light chain format" is an elegant technology that simplifies the purification of a whole IgG-type bispecific antibody. Using this IgG format, the bispecific function can be introduced while maintaining the natural molecular shape of the antibody. In this article, we will first introduce the outline, prospects, and limitations of the common light chain format. Then, we will describe the identification and optimization process for ERY974, an anti-glypican-3 × anti-CD3ε T cell-redirecting bispecific antibody with a common light chain. This format includes one of Chugai's proprietary technologies, termed ART-Ig technology, which consists of a method to identify a common light chain, isoelectric point (pI) engineering to purify the desired bispecific IgG antibody from byproducts, and Fc heterodimerization by an electrostatic steering effect. Furthermore, we describe some tips for de-risking the antibody when engineering a T cell redirecting antibody.

A first-principles prediction on the "healing effect" of graphene preventing carrier trapping near the surface of metal halide perovskites

We introduce a healing effect of graphene preventing carrier trapping by the defects near the surface of metal halide perovskites.

We herein report that surface modification of metal halide perovskites using graphene would be beneficial to improving the energy conversion efficiencies of perovskite solar cells. The present first-principles calculations on MAPbI₃ with a single vacancy created by removing either I, Pb or MA show that the I and Pb vacancies near the surface result in the formation of Pb–Pb and I–I dimers, respectively. They are predicted to yield mid-gap levels, and would degrade the energy conversion efficiency of perovskite solar cells through carrier trapping. The present calculations suggest that when the surface of MAPbI₃ is covered with a graphene sheet, the formation of the carrier trapping dimers would be suppressed. The origin of the “healing effect” of graphene on the lattice defect is ascribed to electronic interactions on the surface, which prevent charge localization at the lattice defects beneath the surface.

An anti–glypican 3/CD3 bispecific T cell–redirecting antibody for treatment of solid tumors

Cancer care is being revolutionized by immunotherapies such as immune checkpoint inhibitors, engineered T cell transfer, and cell vaccines. The bispecific T cell–redirecting antibody (TRAB) is one such promising immunotherapy, which can redirect T cells to tumor cells by engaging CD3 on a T cell and an antigen on a tumor cell. Because T cells can be redirected to tumor cells regardless of the specificity of T cell receptors, TRAB is considered efficacious for less immunogenic tumors lacking enough neoantigens. Its clinical efficacy has been exemplified by blinatumomab, a bispecific T cell engager targeting CD19 and CD3, which has shown marked clinical responses against hematological malignancies. However, the success of TRAB in solid tumors has been hampered by the lack of a target molecule with sufficient tumor selectivity to avoid “on-target off-tumor” toxicity. Glypican 3 (GPC3) is a highly tumor-specific antigen that is expressed during fetal development but is strictly suppressed in normal adult tissues. We developed ERY974, a whole humanized immunoglobulin G–structured TRAB harboring a common light chain, which bispecifically binds to GPC3 and CD3. Using a mouse model with reconstituted human immune cells, we revealed that ERY974 is highly effective in killing various types of tumors that have GPC3 expression comparable to that in clinical tumors. ERY974 also induced a robust antitumor efficacy even against tumors with nonimmunogenic features, which are difficult to treat by inhibiting immune checkpoints such as PD-1 (programmed cell death protein–1) and CTLA-4 (cytotoxic T lymphocyte–associated protein–4). Immune monitoring revealed that ERY974 converted the poorly inflamed tumor microenvironment to a highly inflamed microenvironment. Toxicology studies in cynomolgus monkeys showed transient cytokine elevation, but this was manageable and reversible. No organ toxicity was evident. These data provide a rationale for clinical testing of ERY974 for the treatment of patients with GPC3-positive solid tumors.

Development of defective and persistent Sendai virus vector: a unique gene delivery/expression system ideal for cell reprogramming

The ectopic expression of transcription factors can reprogram differentiated tissue cells into induced pluripotent stem cells. However, this is a slow and inefficient process, depending on the simultaneous delivery of multiple genes encoding essential reprogramming factors and on their sustained expression in target cells. Moreover, once cell reprogramming is accomplished, these exogenous reprogramming factors should be replaced with their endogenous counterparts for establishing autoregulated pluripotency. Complete and designed removal of the exogenous genes from the reprogrammed cells would be an ideal option for satisfying this latter requisite as well as for minimizing the risk of malignant cell transformation. However, no single gene delivery/expression system has ever been equipped with these contradictory characteristics. Here we report the development of a novel replication-defective and persistent Sendai virus (SeVdp) vector based on a noncytopathic variant virus, which fulfills all of these requirements for cell reprogramming. The SeVdp vector could accommodate up to four exogenous genes, deliver them efficiently into various mammalian cells (including primary tissue cells and human hematopoietic stem cells) and express them stably in the cytoplasm at a prefixed balance. Furthermore, interfering with viral transcription/replication using siRNA could erase the genomic RNA of SeVdp vector from the target cells quickly and thoroughly. A SeVdp vector installed with Oct4/Sox2/Klf4/c-Myc could reprogram mouse primary fibroblasts quite efficiently; ∼1% of the cells were reprogrammed to Nanog-positive induced pluripotent stem cells without chromosomal gene integration. Thus, this SeVdp vector has potential as a tool for advanced cell reprogramming and for stem cell research.

Persistent and stable gene expression by a cytoplasmic RNA replicon based on a noncytopathic variant Sendai virus

Persistent and stable expression of foreign genes has been achieved in mammalian cells by integrating the genes into the host chromosomes. However, this approach has several shortcomings in practical applications. For example, large scale production of protein pharmaceutics frequently requires laborious amplification of the inserted genes to optimize the gene expression. The random chromosomal insertion of exogenous DNA also results occasionally in malignant transformation of normal tissue cells, raising safety concerns in medical applications. Here we report a novel cytoplasmic RNA replicon capable of expressing installed genes stably without chromosome insertion. This system is based on the RNA genome of a noncytopathic variant Sendai virus strain, Cl.151. We found that this variant virus establishes stable symbiosis with host cells by escaping from retinoic acid-inducible gene I-interferon regulatory factor 3-mediated antiviral machinery. Using a cloned genome cDNA of Sendai virus Cl.151, we developed a recombinant RNA installed with exogenous marker genes that was maintained stably in the cytoplasm as a high copy replicon (about 4 x 10(4) copies/cell) without interfering with normal cellular function. Strong expression of the marker genes persisted for more than 6 months in various types of cultured cells and for at least two months in rat colonic mucosa without any apparent side effects. This stable RNA replicon is a potentially valuable genetic platform for various biological applications.

A third-generation bisphosphonate, minodronic acid (YM529), successfully prevented the growth of bladder cancer in vitro and in vivo

Minodronic acid (YM529) is a third-generation bisphosphonate (BP) that has been shown to directly and indirectly prevent proliferation, induce apoptosis, and inhibit metastasis of various types of cancer cells. In this study, we have investigated the therapeutic efficacy of YM529 against bladder cancer, both in vitro and in vivo. YM529 inhibited geranylgeranylation as well as farnesylation and reduced the growth of all seven bladder cancer cell lines in a dose- and time-dependent manner in vitro. YM529 demonstrated a good synergistic or additive antiproliferative effect when administered in combination with cisplatin or paclitaxel. Immunohistochemical study revealed YM529 inhibited the prenylation of Rap1A in vivo. YM529 administered systemically did not markedly inhibit the growth of visceral metastases but it showed a significant anticancer effect on bone metastases monitored by an in vivo imaging system. Moreover, intravesical YM529 demonstrated significant growth inhibition in a bladder cancer orthotopic model. No adverse effects were associated with the systemic as well as the intravesical treatment regimens. In conclusion, our study suggests that YM529 may be a potent anticancer agent for bladder cancer. The efficacy and safety of this BP as an agent for combination chemotherapies against bladder cancer should be verified by early-phase clinical trials.

Improved photocatalytic activity of zeolite- and silica-incorporated TiO2 film

Porous TiO2 film was prepared by sol-gel method from TiO2 sol containing polyvinylpyrolidone (PVP). Photocatalytic activity of the film was evaluated by the elimination rate of ethylene. Several adsorbents including zeolite and silica powders were incorporated into the TiO2 film. All the adsorbents enhanced the activity. The optimum adsorbent content was 0.005-0.01 g/ml of the coating sol solution. Silica provided better activity than zeolite. At high humidity and in dry air the activity decreased.

Reconstitution of GDP-mannose transport activity with purified Leishmania LPG2 protein in liposomes

Activated nucleotide sugars required for the synthesis of glycoconjugates within the secretory pathway of eukaryotes are provided by the action of nucleotide sugar transporters (NSTs). Typically, NSTs are studied in microsomal preparations from wild-type or mutant lines; however, in this setting it can be difficult to assess NST properties because of the presence of glycosyltransferases and other interfering activities. Here we have engineered Leishmania donovani to express high levels of an active LPG2 Golgi GDP-Man transporter bearing a C-terminal polyhistidine tag. The functional LPG2-HIS was solubilized, purified by metal affinity chromatography, and reconstituted into phosphatidylcholine-containing liposomes using polystyrene SM-2 beads. The proteoliposomes exhibited robust GDP-Man transport activity with an apparent K(m) of 6.6 mum. Transport activity was enhanced by preloading of GMP and showed specificity for multiple substrates (GDP-Ara and GDP-Fuc). In contrast to the activity in crude microsomes, transport was not dependent on the presence of divalent cations. Thus, reconstitution of transport activity using purified LPG2 protein in liposomes provides firm experimental evidence that a single polypeptide is solely required for NST activity and is able to mediate the uptake of multiple substrates. These studies are relevant to the study of NST structure and function in both protozoan parasites as well as their higher eukaryotic hosts.

Identification of a compensatory mutant (lpg2-REV) of Leishmania major able to survive as amastigotes within macrophages without LPG2-dependent glycoconjugates and its significance to virulence and immunization strategies

Different Leishmania species rely to different extents on abundant glycoconjugates, such as lipophosphoglycan (LPG) and related molecules, in mammalian infections. Previously, we showed that Leishmania major deletion mutants lacking the Golgi GDP-mannose transporter LPG2, which is required for assembly of the dominant phosphoglycan (PG) repeats of LPG, were unable to survive in macrophages. These lpg2- mutants, however, retained the ability to generate asymptomatic, persistent infections in mice. In contrast, Ilg and colleagues showed that Leishmania mexicana LPG2 mutants retained virulence for mice. Here we identified a partial revertant population of the L. major lpg2- mutants (designated lpg2(-)REV) that had regained the ability to replicate in macrophages and induce disease pathology through a compensatory change. Like the lpg2 parent, the lpg2(-)REV revertant was unable to synthesize LPG2-dependent PGs in the promastigote stage and thus remained highly attenuated in the ability to induce infection. However, after considerable delay lpg2(-)REV revertant-infected mice exhibited lesions, and amastigotes isolated from these lesions were able to replicate within macrophages despite the fact that they were unable to synthesize PGs. Thus, in some respects, the lpg2(-)REV amastigotes resemble L. mexicana amastigotes. Future studies of the gene(s) responsible may shed light on the mechanisms employed by L. major to survive in the absence of LPG2-dependent glycoconjugates and may also improve the potential of the lpg2- L. major line to serve as a live parasite vaccine by overcoming its tendency to revert toward virulence.

An in vitro system for developmental and genetic studies of Leishmania donovani phosphoglycans

Glycoconjugates have been shown to play important roles in Leishmania development. However, the ability to study these molecules and other processes would benefit greatly from improved methods for genetic manipulation and analysis of the amastigote stage. This is especially challenging for L. donovani, the agent of the most severe form of leishmaniasis, which can rapidly lose virulence during in vitro culture. Here we report on a clonal subline of an L. donovani 1S2D (LdBob or LdB), which differentiates readily from promastigotes to amastigotes in axenic culture, and maintains this ability during extended parasite cultivation in vitro. This derivative can be plated and transfected efficiently while grown as promastigotes or amastigotes. Importantly, LdB maintains the ability to differentiate while undergoing genetic alterations required for creation of gene knockouts and complemented lines. Like virulent L. donovani, LdB exhibits down-regulation of lipophosphoglycan (LPG) synthesis and up-regulation of A2 protein synthesis in amastigotes. We showed that knockouts of LPG2, encoding a Golgi GDP-mannose transporter, eliminated phosphoglycan synthesis in LdB axenic amastigotes. These and other data suggest that LdB axenic amastigotes will be generally useful as a differentiation model in studies of gene expression, virulence, glycoconjugate function and drug susceptibility in L. donovani.

Persistence without pathology in phosphoglycan-deficient Leishmania major

Leishmania infections involve an acute phase of replication within macrophages, typically associated with pathology. After recovery parasites persist for long periods, which can lead to severe disease upon reactivation. Unlike the role of host factors, parasite factors affecting persistence are poorly understood. Leishmania major lacking phosphoglycans (lpg2-) were unable to survive in sand flies and macrophages, but retained the ability to persist indefinitely in the mammalian host without inducing disease. The L. major lpg2- thus provides a platform for probing parasite factors implicated in persistence and its role in disease and immunity.

Slalom encodes an adenosine 3'-phosphate 5'-phosphosulfate transporter essential for development in Drosophila

Sulfation of all macromolecules entering the secretory pathway in higher organisms occurs in the Golgi and requires the high-energy sulfate donor adenosine 3'-phosphate 5'-phosphosulfate. Here we report the first molecular identification of a gene that encodes a transmembrane protein required to transport adenosine 3'-phosphate 5'-phosphosulfate from the cytosol into the Golgi lumen. Mutations in this gene, which we call slalom, display defects in Wg and Hh signaling, which are likely due to the lack of sulfation of glycosaminoglycans by the sulfotransferase sulfateless. Analysis of mosaic mutant ovaries shows that sll function is also essential for dorsal-ventral axis determination, suggesting that sll transports the sulfate donor required for sulfotransferase activity of the dorsal-ventral determinant pipe.

Cloning, gene structure and dietary regulation of the type-IIc Na/Pi cotransporter in the mouse kidney

We have demonstrated previously that the type-IIc Na/Pi cotransporter is a growth-related renal Na/Pi cotransporter that is highly expressed in kidney of the weaning rat. In the present study, we investigated type-IIc Na/Pi cotransporter function further by cloning the mouse gene and characterizing the corresponding protein. The mouse type-IIc transporter amino acid sequence shows a high degree of similarity to the human (86%) and rat (95%) type-IIc Na/Pi-cotransporters. The mouse gene contained 14 exons and mapped to chromosome 2. The DNA sequence upstream from exon 1 is GC rich. The upstream region does not contain an apparent TATA box, but does contain two dietary Pi-responsive elements, which are potential binding sites for the transcription factor micro E3 (TFE3). Microinjection of mouse type-IIc cRNA into Xenopus oocytes demonstrated sodium-dependent Pi cotransport activity. The affinity for Pi was about 200 microM in 100 mM Na. Feeding adult mice fed a low-Pi diet increased the expression of type-IIc protein in the apical membrane of renal proximal tubular cells. Hybrid depletion studies suggested that the type-IIc transporter contributes to about 30% of Na/Pi cotransport in the kidney of adult mice fed a low-Pi diet. The present study suggests that the type-IIc Na/Pi cotransporter is a functional of renal Pi transporter in adult mice fed a low-Pi diet.

Functional analysis of individual oligosaccharide chains of Sendai virus hemagglutinin-neuraminidase protein

The roles of N-linked glycosylation in the intracellular transport and biological activities of the Sendai virus hemagglutinin-neuraminidase (HN) protein were studied. The protein contains four potential N-glycosylation sites: N77, N448, N499, and N511. By site-directed mutagenesis of these positions, the mature protein contained three N-linked oligosaccharides attached to N77, N499, and N511. The role of each added oligosaccharide in the structure and functions of the protein was identified by characterization of surface expression, hemadsorption, and neuraminidase activities of the corresponding mutant proteins. Elimination of the sites of N499 and N511 had the most detrimental effect, decreasing surface expression and hemadsorption. Elimination of the sites of N77 and N448 had similar but weaker effects. Mutants missing the sites of N499 and N511 were not able to induce syncytia formation in cells expressing mutant HN proteins and the fusion protein. Therefore, the N-linked oligosaccharides attached to N499 and N511 were important for intracellular transport and for the fusion promotion.

Effects of xenon on acetylcholine release in the rat cerebral cortex in vivo

BACKGROUND

We have reported previously the effects of several anaesthetics on cholinergic activity in the central nervous system (CNS). In this study, we report the effects of xenon on cholinergic cell activity.

METHODS

Using in vivo brain microdialysis, we measured acetylcholine (ACh) release in the rat cerebral cortex in vivo during xenon anaesthesia.

RESULTS

Xenon induced an initial increase in ACh release, followed by a gradual decrease. The level of Ach release at 40 min of xenon administration was significantly higher than the control.

CONCLUSIONS

Xenon activates CNS cholinergic cell activity followed by development of acute tolerance.

Effects of propofol on lactate accumulation and oedema formation in focal cerebral ischaemia in hyperglycaemic rats

BACKGROUND

In cerebral ischaemia, hyperglycaemia brings about severe lactate accumulation and neuronal damage when compared with normoglycaemia. Propofol has been known to suppress glucose metabolism in the brain and possess neuroprotective properties in cerebral ischaemia. Therefore, in this study we examined if propofol could attenuate lactate accumulation and neuronal damage in cerebral ischaemia under hyperglycaemic conditions.

METHODS

Ten male wistar rats were divided into two experimental groups: low-dose (approximately 12 mg kg(-1) h(-1)) and high-dose (approximately 60 mg kg(-1) h(-1)) propofol groups (n=5 for each). Following injection of 2 g kg(-1) glucose intraperitoneally, the middle cerebral artery was occluded for 1 h, and then reperfused for the following 2 h. Lactate accumulation and oedema formation were estimated consecutively using nuclear magnetic resonance (NMR) techniques.

RESULTS

Lactate accumulation and oedema formation increased continuously during ischaemia and reperfusion in the low-dose propofol group, which was attenuated in the high-dose propofol group. Lactate/NAA (N-acetylaspartate) ratio (as an index of lactate accumulation) 60 and 120 min after reperfusion were 2.67 and 3.26 in low-dose group and 0.30 and 0.10 in high-dose group. For NMR images the number of pixels with a low average diffusion coefficient (an index of the oedema formation), 60 and 120 min after reperfusion were 250.0 and 317.8 in low-dose group, and 16.0 and 12.4 in high-dose group.

CONCLUSION

High-dose propofol attenuated lactate accumulation and oedema formation in cerebral ischaemia in hyperglycaemic rats.

N-linked oligosaccharide chains of Sendai virus fusion protein determine the interaction with endoplasmic reticulum molecular chaperones

The selectivity and individual roles of the N-linked oligosaccharide chains of Sendai virus fusion protein (F protein) in the interaction with endoplasmic reticulum molecular chaperones were investigated by analyses of transient expression of single N-glycosylation mutants and sequential immunoprecipitation. We demonstrated differential interactions depending on the location of the N-linked oligosaccharide chain, and showed that these interactions were correlated with the folding and transport of F proteins. Moreover, mutant F proteins that lacked the specific N-linked oligosaccharide chains required for disulfide bond formation showed increased association with ERp57.

Human and Drosophila UDP-galactose transporters transport UDP-N-acetylgalactosamine in addition to UDP-galactose

A putative Drosophila nucleotide sugar transporter was characterized and shown to be the Drosophila homologue of the human UDP-Gal transporter (hUGT). When the Drosophila melanogaster UDP-Gal transporter (DmUGT) was expressed in mammalian cells, the transporter protein was localized in the Golgi membranes and complemented the UDP-Gal transport deficiency of Lec8 cells but not the CMP-Sia transport deficiency of Lec2 cells. DmUGT and hUGT were expressed in Saccharomyces cerevisiae cells in functionally active forms. Using microsomal vesicles isolated from Saccharomyces cerevisiae expressing these transporters, we unexpectedly found that both hUGT and DmUGT could transport UDP-GalNAc as well as UDP-Gal. When amino-acid residues that are conserved among human, murine, fission yeast and Drosophila UGTs, but are distinct from corresponding ones conserved among CMP-Sia transporters (CSTs), were substituted by those found in CST, the mutant transporters were still active in transporting UDP-Gal. One of these mutants in which Asn47 was substituted by Ala showed aberrant intracellular distribution with concomitant destabilization of the protein product. However, this mutation was suppressed by an Ile51 to Thr second-site mutation. Both residues were localized within the first transmembrane helix, suggesting that the structure of the helix contributes to the stabilization and substrate recognition of the UGT molecule.

Modulation of event-related potentials in normal human subjects by visual divided attention to spatial and color factors

We investigated how visual event-related potentials (ERPs) are modulated by visual divided attention using an S1-S2 paradigm. Stimulus S2 consisted of non-target stimuli (Stimulus 1, 2, 3) and a target stimulus (Stimulus 4). The spatial/color factor was compared between S1 and S2: same/same (Stimulus 1); same/different (Stimulus 2); different/same (Stimulus 3); and different/different (Stimulus 4). The P1/N1 (90 approximately 150 ms) showed significantly greater amplitude in Stimulus 3 than in Stimuli 1 and 2. The N2 (230 approximately 290ms) showed significantly greater amplitude in Stimulus 2 than in Stimuli 1 and 3. We assumed that the P1/N1 was related to spatial attention, enhanced by alterations to the spatial factor, and that the N2 was related to color attention, enhanced by alterations to the color factor.

Human L-type amino acid transporter 1 (LAT1): characterization of function and expression in tumor cell lines

System L is a major nutrient transport system responsible for the transport of large neutral amino acids including several essential amino acids. We previously identified a transporter (L-type amino acid transporter 1: LAT1) subserving system L in C6 rat glioma cells and demonstrated that LAT1 requires 4F2 heavy chain (4F2hc) for its functional expression. Since its oncofetal expression was suggested in the rat liver, it has been proposed that LAT1 plays a critical role in cell growth and proliferation. In the present study, we have examined the function of human LAT1 (hLAT1) and its expression in human tissues and tumor cell lines. When expressed in Xenopus oocytes with human 4F2hc (h4F2hc), hLAT1 transports large neutral amino acids with high affinity (K(m)= approximately 15- approximately 50 microM) and L-glutamine and L-asparagine with low affinity (K(m)= approximately 1.5- approximately 2 mM). hLAT1 also transports D-amino acids such as D-leucine and D-phenylalanine. In addition, we show that hLAT1 accepts an amino acid-related anti-cancer agent melphalan. When loaded intracellularly, L-leucine and L-glutamine but not L-alanine are effluxed by extracellular substrates, confirming that hLAT1 mediates an amino acid exchange. hLAT1 mRNA is highly expressed in the human fetal liver, bone marrow, placenta, testis and brain. We have found that, while all the tumor cell lines examined express hLAT1 messages, the expression of h4F2hc is varied particularly in leukemia cell lines. In Western blot analysis, hLAT1 and h4F2hc have been confirmed to be linked to each other via a disulfide bond in T24 human bladder carcinoma cells. Finally, in in vitro translation, we show that hLAT1 is not a glycosylated protein even though an N-glycosylation site has been predicted in its extracellular loop, consistent with the property of the classical 4F2 light chain. The properties of the hLAT1/h4F2hc complex would support the roles of this transporter in providing cells with essential amino acids for cell growth and cellular responses, and in distributing amino acid-related compounds.

[Cellular mechanisms in proximal tubular handling of phosphate]

In the kidney, reabsorption of filtered inorganic phosphate (Pi) takes place along the proximal tubules and is controlled by a variety of hormones (e.g.parathyroid hormone, PTH). Three structurally unrelated sodium-dependent phosphate (Na/Pi) cotransporter families have been identified. Targeted inactivation of the type IIa Na/Pi cotransporter gene (npt2) provided strong evidence that - 70% of Na-dependent Pi transport across the brush border membrane is mediated by the type IIa Na/Pi cotransporter. The type IIa cotransporter represents the major target for PTH. The type IIa cotransporter interacts with various PDZ proteins that might be responsible for the apical sorting, PTH controlled endocytosis or the lysosomal sorting internalized type IIa cotransporter.

Multiple osteochondroses of bilateral knee joints

We experienced a patient with a combination of multiple osteochondroses: Blount's disease, bipartite patella, and Sinding-Larsen-Johansson disease in the left knee, and a combination of bipartite patella and Osgood-Schlatter disease in the right knee. The patient was a healthy, active 12-year-old boy with bilateral knee pain. He had been diagnosed with Blount's disease of the left tibia at 2 years of age, and had been treated with open wedge osteotomy. He was diagnosed with bilateral bipartite patellae at the age of 9 years, and was diagnosed with Osgood-Schlatter disease in the right knee and Sinding-Larsen-Johansson disease in the left knee at 10 years of age. The second growth spurt was observed during this period. At 11 years of age, he was diagnosed with an osteochondral fracture of the left lateral femoral condyle and was observed without surgery. This patient showed the sequential appearance of an ossification disorder, probably due to the abnormal response of enchondral ossification to mechanical stress. Overuse in this growth period may have played a role in the development of these osteochondroses. The osteochondral fracture was probably caused by a disruption at one of the weakest parts of the developing skeleton, between the ossification center and the overlying cartilage in the background of an ossification disorder.

Molecular events involved in up-regulating human Na+-independent neutral amino acid transporter LAT1 during T-cell activation

We investigated the regulation of system-L amino acid transporter (LAT1) during T-cell activation. In quiescent T-cells, L-leucine transport is mediated mainly by the system-L amino acid transport system and is increased significantly during T-cell activation by PMA and ionomycin. In quiescent T-cells, the LAT1 protein was heterocomplexed with 4F2 heavy chain (4F2hc) in the plasma membrane. During T-cell activation, the amounts of 4F2hc and LAT1 heterocomplex were significantly elevated compared with those in quiescent T-cells. In addition, by Northern-blot analysis, these increments were found to be due to elevated levels of LAT1 and 4F2hc mRNA. Transient expression of constructs comprising various LAT1 gene promoter fragments, which contained all three of the GC boxes, was sufficient for promoting luciferase expression in Jurkat T-cells, but the promoter of the LAT1 gene did not respond to PMA and ionomycin. Similar observations were observed in the human 4F2hc gene promoter. In nuclear run-on assay, the LAT1 and 4F2hc genes were actively transcribed even in quiescent T-cells, but the low levels of both transcripts were shown to be the result of a block to transcription elongation within the exon 1 intron 1 regions. These findings indicated that a removal of the block to mRNA elongation stimulates the induction of system-L amino acid transporter gene transcripts (LAT1 and 4F2hc) in activated T-cells.

Bone tunnel enlargement after anterior cruciate ligament reconstruction using hamstring tendons

We retrospectively reviewed 87 anterior cruciate ligament reconstructions using autogenous hamstring tendons with the Endobutton technique to investigate the relationship between bone tunnel enlargement and clinical outcome and to identify factors that contribute to the enlargement. The clinical outcome was evaluated using the Lysholm score and KT-1000 arthrometer. The location of the femoral tunnel with respect to Blumensaat's line, the tibial tunnel with respect to the tibial plateau, and the angle between the femoral tunnel and Blumensaat's line (femoral tunnel angle) were measured. Bone tunnel enlargement was observed in 32 patients (37%). Enlargement occurred in 22 of the femoral tunnels and 26 of the tibial tunnels. Enlargement of both tunnels occurred in 16 knees. There was no statistical difference in Lysholm scores or KT-1000 arthrometer measurements between the enlarged group and the unenlarged group. The femoral tunnel was placed more anteriorly in the enlarged femoral tunnel group than in the unenlarged femoral tunnel group. The tibial tunnel was placed more anteriorly in the enlarged tibial tunnel group than in the unenlarged tibial tunnel group. The femoral tunnel angle was significantly smaller in the enlarged femoral tunnel group than in the femoral unenlarged group. Gender, patient age, intraoperative isometricity, and graft size were not significant factors. Bone tunnel enlargement was not correlated with the clinical outcome measures. We conclude that the main factor associated with tunnel enlargement are the locations and angles of the tunnels. The windshield-wiper motion of the graft may be enhanced by changing tension in the graft due to tunnel malposition. An acute femoral tunnel angle may increase the mechanical stress on the anterior margin of the femoral tunnel.

Functional repression of Islet-2 by disruption of complex with Ldb impairs peripheral axonal outgrowth in embryonic zebrafish

Islet-2 is a LIM/homeodomain-type transcription factor of the Islet-1 family expressed in embryonic zebrafish. Two Islet-2 molecules bind to the LIM domain binding protein (Ldb) dimers. Overexpression of the LIM domains of Islet-2 or the LIM-interacting domain of Ldb proteins prevented binding of Islet-2 to Ldb proteins in vitro and caused similar in vivo defects in positioning, peripheral axonal outgrowth, and neurotransmitter expression by the Islet-2-positive primary sensory and motor neurons as the defects induced by injection of Islet-2-specific antisense morpholino oligonucleotide. These and other experiments, i.e., mosaic analysis, coexpression of full-length Islet-2, and overexpression of the chimeric LIM domains derived from two different Islet-1 family members, demonstrated that Islet-2 regulates neuronal differentiation by forming a complex with Ldb dimers and possibly with some other Islet-2-specific cofactors.

Identification and functional analysis of three isoforms for the Na+-dependent phosphate co-transporter (NaPi-2) in rat kidney

We have isolated three unique NaPi-2-related protein cDNAs (NaPi-2alpha, NaPi-2beta and NaPi-2gamma) from a rat kidney library. NaPi-2alpha cDNA encodes 337 amino acids which have high homology to the N-terminal half of NaPi-2 containing three transmembrane domains. NaPi-2beta encodes 327 amino acids which are identical to the N-terminal region of NaPi-2 containing four transmembrane domains, whereas the 146 amino acids in the C-terminal region are completely different. In contrast, NaPi-2gamma encodes 268 amino acids which are identical to the C-terminal half of NaPi-2. An analysis of phage and cosmid clones indicated that the three related proteins were produced by alternative splicing in the NaPi-2 gene. In a rabbit reticulocyte lysate system, NaPi-2alpha, beta and gamma were found to be 36, 36 and 29 kDa polypeptides, respectively. NaPi-2alpha and NaPi-2gamma were glycosylated and revealed to be 45 and 35 kDa proteins, respectively. A functional analysis demonstrated that NaPi-2gamma and alpha markedly inhibited NaPi-2 activity in Xenopus oocytes. The results suggest that these short isoforms may function as a dominant-negative inhibitor of the full-length transporter.

Long-term results of non-operative treatment of anterior cruciate ligament injury

We retrospectively reviewed the record of 89 patients with complete anterior cruciate ligament injury, documented by arthroscopic examination to investigate the long-term results in relation to the generation of osteoarthritis. The mean age of the patients was 34.9 years at follow-up and the mean duration of follow-up was 12.0 years. The mean Lysholm score was 89 points at follow-up. The mean Tegner activity score was 5.7 points before injury and 4.5 points at follow-up. Plain radiographs revealed 63% of osteoarthritis and 37% of which had joint space narrowing. The age of the patients, the level of sports activity, the history of meniscectomy, obesity and the osteoarthritis of the contralateral knee were found to be significant risk factors in osteoarthritis after anterior cruciate ligament injury. The most influential factor for osteoarthritis was considered meniscectomy, in combination with the risk factors of primary osteoarthritis. It should also be noted that modification of sports activity level was the most important factor for avoiding the combined injury of meniscus and osteoarthritis.

Radiosurgery of meningeal melanocytoma

The authors present a case of meningeal melanocytoma arising from Meckel's cave. A coal-black, vascular tumor was partially removed by surgery. Histopathologically, the tumor lacked anaplastic features. Immunohistochemical studies confirmed that the tumor was of neuroectodermal origin and had low proliferating activity. The patient underwent gamma knife radiosurgery for the residual tumor, in which 25 Gy of radiation was delivered to the tumor margin. Three years after irradiation, the tumor showed marked shrinkage without complication.

Secondary hyperparathyroidism and phosphate sensing in parathyroid glands

Retention of inorganic phosphate (Pi) and associated hyperphosphatemia are important development of hyperparathyroidism secondary to renal failure. The beneficial effect of a low-Pi diet in the prevention of hyperparathyroidism can be attributed to the decrease in PTH secretion. This effect of Pi may be mediated by specific molecules in the parathyroid cell membrane. A complementary DNA encoding a Na(+)-Pi co-transporter, termed rat PiT-1, has been isolated from rat parathyroid. The amount of PiT-1 mRNA in the parathyroid is controlled by vitamin D and dietary Pi, which are the most important regulators of PTH secretion. The parathyroid Pi transporter may mediate the effects of extracellular Pi and PTH secretion in secondary hyperparathyroidism. In this study, we focus on the function of Na/Pi co-transporters in the parathyroid glands as inorganic Pi sensor.

Transport properties of a system y+L neutral and basic amino acid transporter. Insights into the mechanisms of substrate recognition

The properties of system y(+)L-mediated transport were investigated on rat system y(+)L transporter, ry(+)LAT1, coexpressed with the heavy chain of cell surface antigen 4F2 in Xenopus oocytes. ry(+)LAT1-mediated transport of basic amino acids was Na(+)-independent, whereas that of neutral amino acids, although not completely, was dependent on Na(+), as is typical of system y(+)L-mediated transport. In the absence of Na(+), lowering of pH increased leucine transport, without affecting lysine transport. Therefore, it is proposed that H(+), besides Na(+) and Li(+), is capable of supporting neutral amino acid transport. Na(+) and H(+) augmented leucine transport by decreasing the apparent K(m) values, without affecting the V(max) values. We demonstrate that although ry(+)LAT1-mediated transport of [(14)C]l-leucine was accompanied by the cotransport of (22)Na(+), that of [(14)C]l-lysine was not. The Na(+) to leucine coupling ratio was determined to be 1:1 in the presence of high concentrations of Na(+). ry(+)LAT1-mediated leucine transport, but not lysine transport, induced intracellular acidification in Chinese hamster ovary cells coexpressing ry(+)LAT1 and 4F2 heavy chain in the absence of Na(+), but not in the presence of physiological concentrations of Na(+), indicating that cotransport of H(+) with leucine occurred in the absence of Na(+). Therefore, for the substrate recognition by ry(+)LAT1, the positive charge on basic amino acid side chains or that conferred by inorganic monovalent cations such as Na(+) and H(+), which are cotransported with neutral amino acids, is presumed to be required. We further demonstrate that ry(+)LAT1, due to its peculiar cation dependence, mediates a heteroexchange, wherein the influx of substrate amino acids is accompanied by the efflux of basic amino acids.

Functional analysis of the individual oligosaccharide chains of sendai virus fusion protein

The roles of N-linked glycosylation in the intracellular transport and fusion activity of the Sendai virus fusion (F) protein were studied. Each of three potential glycosylation motifs (designated g1, g2, and g3) in the F protein was mutated separately or in combination with the other sites. When the mutant F proteins were transiently expressed in COS cells, they showed significant changes in electrophoretic mobility, indicating that all three motifs in the F protein are glycosylated. Glycosylation-defective mutants which lacked the g2-oligosaccharide chain showed decreased immunoreactivity with a monoclonal antibody specific for the native conformation and were inefficiently transported to the cell surface. Such mutants, with the exception of a double mutant lacking g1 and g2-oligosaccharide chains, were also not able to induce syncytia formation when cells expressing them plus the hemagglutinin-neuraminidase protein were treated with trypsin. Mutations at the other glycosylation sites did not significantly affect the immunoreactivity with the monoclonal antibody or the efficiency of intracellular transport of the F protein. These results indicate that the N-linked oligosaccharide chain attached at g2 is important for efficient intracellular transport and for the fusion activity of the F protein.

Neurovascular decompression for idiopathic tarsal tunnel syndrome: technical note

OBJECTIVE

The surgical outcome of idiopathic tarsal tunnel syndrome (TTS) is reported to be worse than that attributable to ganglion, tarsal coalition, or tumour, and therefore further development in the surgical treatment for idiopathic TTS is considered to be necessary. Here the efficacy of neurovascular decompression for patients with idiopathic TTS is evaluated.

METHODS

Twelve feet from nine patients with idiopathic TTS were treated. The patients were aged 52-78 years (mean 64.6 years), and all of them complained of pain or dysaesthesia of the sole of the foot. The posterior tibial nerve was freed from the attached arteriovenous complex (posterior tibial artery and veins). The dissected nerve had a flattened appearance in all of the patients, suggesting nerve compression by the adjacent arteriovenous complex and superficially by the flexor retinaculum. A graft of fat was inserted as both a cushion and an antiadhesive between the vessels and the nerve to achieve neurovascular decompression.

RESULTS

Patients on whom neurovascular decompression was performed had resolution or lessening of symptoms in their feet. Neither wound infection nor recurrence of symptoms was found during the follow up period (mean 26.8 months).

CONCLUSION

Neurovascular compression syndrome plays a part in idiopathic TTS, and adding neurovascular decompression to resection of the flexor retinaculum is effective.

[Intraoperative autologous blood transfusion was effective in a massive blood loss during living-related donor liver transplantation]

We have experienced massive blood loss (> 80,000 g) during living-related donor liver transplantation (LRDLT) of a 14-year old girl with biliary atresia. As available homologous blood was not sufficient, we transfused autologous blood (13,400 ml) during operation. Although immunosuppressant was administered to the patient, severe infection did not occur for 10 days after the operation. Cold ischemia time of the graft liver was about 16 hr, but her postoperative liver function was well-maintained. The case suggests that intraoperative autologus blood transfusion is effective if homologous blood is insufficient during LRDLT.

Estimation of the lethal toluene concentration from the accidental death of painting workers

To determine the potentially lethal level of thinner concentration in the air, we measured the concentration of toluene in the blood and others of three patients who suffered severe acute thinner intoxication between 4 January 1996 and 21 April 1997 in Ube city. The concentration of toluene in blood were 30.2 mg/L in died patient, and 13.7 mg/L and 17.5 mg/L in recovered patients, respectively. By extrapolation from the results of our previous toxicokinetic research on toluene poisoning in anesthetized dogs, the fatal concentration of toluene was estimated to be approximately 1800 to 2000 ppm for 1-hour exposure.

Boomerang deformity of cervical spinal cord migrating between split laminae after laminoplasty

Patients with cervical compression myelopathy were studied to elucidate the mechanism underlying boomerang deformity, which results from the migration of the cervical spinal cord between split laminae after laminoplasty with median splitting of the spinous processes (boomerang sign). Thirty-nine cases, comprising 25 patients with cervical spondylotic myelopathy, 8 patients with ossification of the posterior longitudinal ligament, and 6 patients with cervical disc herniation with developmental canal stenosis, were examined. The clinical and radiological findings were retrospectively compared between patients with (B group, 8 cases) and without (C group, 31 cases) boomerang sign. Moderate increase of the grade of this deformity resulted in no clinical recovery, although there was no difference in clinical recovery between the two groups. Most boomerang signs developed at the C4/5 and/or C5/6 level, where maximal posterior movement of the spinal cord was achieved. Widths between lateral hinges and between split laminae in the B group were smaller than in the C group. Flatness of the spinal cord in the B group was more severe than in the C group. In conclusion, the boomerang sign was caused by posterior movement of the spinal cord, narrower enlargement of the spinal canal and flatness of the spinal cord.

Clinicopathological study of intracranial fusiform and dolichoectatic aneurysms : insight on the mechanism of growth

BACKGROUND AND PURPOSE

Intracranial fusiform aneurysms can be divided into 2 clinically different subtypes: acute dissecting aneurysms and chronic fusiform or dolichoectatic aneurysms. Of these 2, the natural history and growth mechanism of chronic fusiform aneurysms remains unknown.

METHODS

A consecutive series of 16 patients with chronic fusiform aneurysms was studied retrospectively to clarify patient clinical and neuroradiological features. Aneurysm tissues were obtained from 8 cases and were examined to identify histological features that could correspond to the radiological findings.

RESULTS

Four histological features were found: (1) fragmentation of internal elastic lamina (IEL), (2) neoangiogenesis within the thickened intima, (3) intramural hemorrhage (IMH) and thrombus formation, and (4) repetitive intramural hemorrhages from the newly formed vessels within thrombus. IEL fragmentation was found in all cases, which suggests that this change may be one of the earliest processes of aneurysm formation. MRI or CT detected IMH, and marked contrast enhancement of the inside of the aneurysm wall (CEI) on MRI corresponded well with intimal thickening. Eight of 9 symptomatic cases but none of 7 asymptomatic cases presented with both radiological features.

CONCLUSIONS

Data suggest that chronic fusiform aneurysms are progressive lesions that start with IEL fragmentation. Formation of IMH seems to be a critical event necessary for lesions to become symptomatic and progress, and this can be monitored on MRI. Knowledge of this possible mechanism of progression and corresponding MRI characteristics could help determine timing of surgical intervention.

Identification and characterization of a Na(+)-independent neutral amino acid transporter that associates with the 4F2 heavy chain and exhibits substrate selectivity for small neutral D- and L-amino acids

A cDNA was isolated from the mouse brain that encodes a novel Na(+)-independent neutral amino acid transporter. The encoded protein, designated as Asc-1 (asc-type amino acid transporter 1), was found to be structurally related to recently identified mammalian amino acid transporters for the transport systems L, y(+)L, x(C)(-), and b(0,+), which are linked, via a disulfide bond, to the type II membrane glycoproteins, 4F2 heavy chain (4F2hc), or rBAT (related to b(0,+) amino acid transporter). Asc-1 required 4F2hc for its functional expression. In Western blot analysis in the nonreducing condition, a 118-kDa band, which seems to correspond to the heterodimeric complex of Asc-1 and 4F2hc, was detected in the mouse brain. The band shifted to 33 kDa in the reducing condition, confirming that Asc-1 and 4F2hc are linked via a disulfide bond. Asc-1-mediated transport was not dependent on the presence of Na(+) or Cl(-). Although Asc-1 showed a high sequence homology (66% identity at the amino acid level) to the Na(+)-independent broad scope neutral amino acid transporter LAT2 (Segawa, H., Fukasawa, Y., Miyamoto, K., Takeda, E., Endou, H., and Kanai, Y. (1999) J. Biol. Chem. 274, 19745-19751), Asc-1 also exhibited distinctive substrate selectivity and transport properties. Asc-1 preferred small neutral amino acids such as Gly, L-Ala, L-Ser, L-Thr, and L-Cys, and alpha-aminoisobutyric acid as substrates. Asc-1 also transported D-isomers of the small neutral amino acids, in particular D-Ser, a putative endogenous modulator of N-methyl-D-aspartate-type glutamate receptors, with high affinity. Asc-1 operated preferentially, although not exclusively, in an exchange mode. Asc-1 mRNA was detected in the brain, lung, small intestine, and placenta. The functional properties of Asc-1 seem to be consistent with those of a transporter subserving the Na(+)-independent small neutral amino acid transport system asc.

Regulation of intestinal Na+-dependent phosphate co-transporters by a low-phosphate diet and 1,25-dihydroxyvitamin D3

In a study of the rat intestinal P(i) transport system, an activator protein for rat Na/P(i) co-transport system (PiUS) was isolated and characterized. We also investigated the effects of restriction of vitamin D and P(i) (two of the most important physiological and pathophysiological regulators of P(i) absorption in the small intestine) on intestinal P(i) transport activity and the expression of Na/P(i) co-transporters that are expressed in rat small intestine. Rat PiUS encodes a 424-residue protein with a calculated molecular mass of 51463 Da. The microinjection of rat PiUS into Xenopus oocytes markedly stimulated Na(+)-dependent P(i) co-transport activity. In rats fed with a low-P(i) diet, Na(+)-dependent P(i) co-transport activity was increased approx. 2-fold compared with that of rats fed a normal P(i) diet. Kinetic studies demonstrated that this increased activity was due to an elevation of V(max) but not K(m). The PiUS mRNA levels showed an approximate doubling in the rats fed with the low-P(i) diet compared with those fed with the normal P(i) diet. In addition, after the administration of 1, 25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] to vitamin D-deficient animals, the P(i) uptake was significantly increased in the Na(+)-dependent component in the brush border membrane vesicle (BBMV) at 24 and 48 h. In addition, we found a further high-affinity Na/P(i) co-transport system in the BBMV isolated from the vitamin D-replete animals. The levels of type III Na/P(i) co-transporter PiT-2 mRNA were increased 24 and 48 h after 1,25-(OH)(2)D(3) administration to vitamin D-deficient animals, whereas PiUS and the type IIb Na/P(i) co-transporter mRNA levels were unchanged. In conclusion, we first cloned a rat activator protein, PiUS, and then studied its role along with that of other type III Na/P(i) co-transporters. PiUS and PiT-2 might be important components in the regulation of the intestinal P(i) transport system by P(i) restriction and 1,25-(OH)(2)D(3).