Concurrent and predictive validity of the Mini Nutritional Assessment Short-Form and the Geriatric Nutritional Risk Index in older stroke rehabilitation patients.

BACKGROUND: Malnutrition may worsen clinical outcomes in stroke patients. Few malnutrition screening tools have been validated in the rehabilitation setting. The present study aimed to assess the concurrent and predictive validity of two malnutrition screening tools. METHODS: We retrospectively collected scores for the Mini Nutritional Assessment Short-Form (MNA-SF) and the Geriatric Nutritional Risk Index (GNRI) in consecutive stroke patients aged ≥65 years in a rehabilitation hospital. Concurrent validity was confirmed against the European Society for Clinical Nutrition and Metabolism diagnostic criteria for malnutrition (ESPEN-DCM). Malnutrition risk within the ESPEN-DCM process was assessed using the Malnutrition Universal Screening Tool. Cut-off values with maximum Youden index, and with sensitivity (Se) >90% and specificity (Sp) >50%, were defined as appropriate for identification and screening of malnutrition, respectively. The Functional Independence Measure and discharge destination were used to explore predictive validity. RESULTS: Overall, 420 patients were analysed. Of these, we included 125 patients in the malnutrition group and 295 in the non-malnutrition group based on the ESPEN-DCM. Cut-off values for the identification and screening of malnutrition were 5 (Se: 0.78; Sp: 0.85) and 7 (Se: 0.96; Sp: 0.57) for the MNA-SF; 92 (Se: 0.74; Sp: 0.84) and 98 (Se: 0.93; Sp: 0.50) for the GNRI, respectively. The GNRI predicted discharge to acute care hospital, whereas the MNA-SF did not predict all outcome measures. CONCLUSIONS: The MNA-SF and the GNRI have a fair concurrent validity in stroke patients, although lower cut-off values than currently used were required for the MNA-SF. The GNRI exhibits good predictive validity for discharge destination.

Introducing HPV vaccine and scaling up screening procedures to prevent deaths from cervical cancer in Japan: a cost-effectiveness analysis.

OBJECTIVE: To assess the cost-effectiveness of universal vaccination of 11-year-old girls against human papillomavirus (HPV) infection and increased screening coverage to prevent cervical cancer in Japan where the coverage of Papanicolaou smears is very low. DESIGN: A cost-utility analysis from a societal perspective. SETTING: Japan, 2010. POPULATION: The female Japanese population aged 11 years or older. METHODS: A Markov model of the natural history of cervical cancer was constructed to compare six strategies: i.e. a screening coverage rate of 20, 50 and 80% with and without routine vaccination at age 11. MAIN OUTCOME MEASURES: Cervical cancer incidence, quality-adjusted life years (QALYs), costs and incremental cost-effectiveness ratios. RESULTS: Expanding the coverage of Papanicolaou smears from the current level of 20-50 and 80% yields a 45.5 and 63.1% reduction in cervical cancer incidence, respectively. Impact of combined strategies increases with coverage. Coverages of 20, 50 and 80% showed a 66.1, 80.9 and 86.8% reduction in disease, respectively. The costs of strategies with vaccination are four times higher than the cost of strategies without vaccination. Vaccinating all 11-year-old girls with bivalent vaccines with a Papanicolaou smear coverage rate of 50% is likely to be the most cost-effective option among the six strategies. CONCLUSIONS: The introduction of HPV vaccination in Japan is cost-effective as in other countries. It is more cost-effective to increase the coverage of the Papanicolaou smear along with the universal administration of HPV vaccine.

Multifunctional transcription factor TFII-I is an activator of BRCA1 function.

BACKGROUND: The TFII-I is a multifunctional transcriptional factor known to bind specifically to several DNA sequence elements and to mediate growth factor signalling. A microdeletion at the chromosomal location 7q11.23 encoding TFII-I and the related family of transcription factors may result in the onset of Williams-Beuren syndrome, an autosomal dominant genetic disorder characterised by a unique cognitive profile, diabetes, hypertension, anxiety, and craniofacial defects. Hereditary breast and ovarian cancer susceptibility gene product BRCA1 has been shown to serve as a positive regulator of SIRT1 expression by binding to the promoter region of SIRT1, but cross talk between BRCA1 and TFII-I has not been investigated to date. METHODS: A physical interaction between TFII-I and BRCA1 was explored. To determine pathophysiological function of TFII-I, its role as a transcriptional cofactor for BRCA1 was investigated. RESULTS: We found a physical interaction between the carboxyl terminus of TFII-I and the carboxyl terminus of BRCA1, also known as the BRCT domain. Endogenous TFII-I and BRCA1 form a complex in nuclei of intact cells and formation of irradiation-induced nuclear foci was observed. We also showed that the expression of TFII-I stimulates the transcriptional activation function of BRCT by a transient expression assay. The expression of TFII-I also enhanced the transcriptional activation of the SIRT1 promoter mediated by full-length BRCA1. CONCLUSION: These results revealed the intrinsic mechanism that TFII-I may modulate the cellular functions of BRCA1, and provide important implications to understand the development of breast cancer.

Identification of DBC1 as a transcriptional repressor for BRCA1.

BACKGROUND: DBC1/KIAA1967 (deleted in breast cancer 1) is a putative tumour-suppressor gene cloned from a heterozygously deleted region in breast cancer specimens. Caspase-dependent processing of DBC1 promotes apoptosis, and depletion of endogenous DBC1 negatively regulates p53-dependent apoptosis through its specific inhibition of SIRT1. Hereditary breast and ovarian cancer susceptibility gene product BRCA1, by binding to the promoter region of SIRT1, is a positive regulator of SIRT1 expression. METHODS: A physical interaction between DBC1 and BRCA1 was investigated both in vivo and in vitro. To determine the pathophysiological significance of DBC1, its role as a transcriptional factor was studied. RESULTS: We found a physical interaction between the amino terminus of DBC1 and the carboxyl terminus of BRCA1, also known as the BRCT domain. Endogenous DBC1 and BRCA1 form a complex in the nucleus of intact cells, which is exported to the cytoplasm during ultraviolet-induced apoptosis. We also showed that the expression of DBC1 represses the transcriptional activation function of BRCT by a transient expression assay. The expression of DBC1 also inhibits the transactivation of the SIRT1 promoter mediated by full-length BRCA1. CONCLUSION: These results revealed that DBC1 may modulate the cellular functions of BRCA1 and have important implications in the understanding of carcinogenesis in breast tissue.

Decreased pregnancy rate is linked to abnormal uterine peristalsis caused by intramural fibroids.

BACKGROUND: The relationship between fibroids and infertility remains an unsolved question, and management of intramural fibroids is controversial. During the implantation phase, uterine peristalsis is dramatically reduced, which is thought to facilitate embryo implantation. Our aims were to evaluate (i) the occurrence and frequency of uterine peristalsis in infertile women with intramural fibroids and (ii) whether the presence of uterine peristalsis decreases the pregnancy rate. METHODS: Ninety-five infertile patients with uterine fibroids were examined using magnetic resonance imaging (MRI). Inclusion criteria were as follows: (i) presence of intramural fibroids, excluding submucosal type; (ii) no other significant infertility factors (excluding endometriosis); and (iii) regular menstrual cycles, and MRI performed at the time of implantation (luteal phase day 5-9). The frequency of junctional zone movement was evaluated using cine-mode-display MRI. After MRI, patients underwent infertility treatment for up to 4 months, and the pregnancy rate was evaluated prospectively. RESULTS: Fifty-one patients fulfilled the inclusion criteria, and 29 (57%) and 22 (43%) patients were assigned to the low (0 or 1 time/3 min) or high frequency (≥ 2 times/3 min) uterine peristalsis group, respectively. Endometriosis incidence was the same in both groups. Ten out of the 29 patients (34%) in the low-frequency group achieved pregnancy, compared with none of the 22 patients (0%) in the high-frequency group (P< 0.005). Comparing pregnant and non-pregnant cases, 4 of 10 patients (40%) and 9 of 41 patients (22%), respectively, had endometriosis (not significant). CONCLUSIONS: A higher frequency of uterine peristalsis during the mid-luteal phase might be one of the causes of infertility associated with intramural-type fibroids.

Dose effects of oral estradiol on bone mineral density in Japanese women with osteoporosis.

OBJECTIVES: This 2-year study compared 0.5 and 1.0 mg oral estradiol (E(2)), with or without levonorgestrel (LNG), for the treatment of postmenopausal osteoporosis in Japanese women. METHODS: Japanese women with osteoporosis after natural menopause or bilateral oophorectomy were randomized to receive E(2) 0.5 or 1.0 mg/day with LNG 40 microg as required, or placebo, for 52 weeks. Women treated with E(2) in the first year continued therapy at the same doses in the second year. Efficacy, safety and pharmacokinetics were assessed. RESULTS: There were 73 women randomized to E(2) 0.5 mg, 157 to E(2) 1.0 mg and 79 to placebo. Lumbar bone mineral density at 52 weeks increased significantly more with E(2) 1.0 mg (p < 0.001) and 0.5 mg (p < 0.001) than with placebo (no change). After 2 years, a 10% increase in bone mineral density with E(2) 1.0 mg was significantly greater than with E(2) 0.5 mg (8%; p = 0.008). E(2) was associated with an acceptable safety and tolerability profile, with slightly more adverse events with E(2) 1.0 than 0.5 mg. Serum E(2) concentration increased in a dose-dependent manner. CONCLUSION: This study showed that E(2), at both 1.0 mg and 0.5 mg doses, was effective in increasing bone mineral density with an acceptable safety and tolerability profile in Japanese postmenopausal women with osteoporosis but that the bone mineral density response was higher with the 1.0 mg dose.

The oncogenic mutation in the pleckstrin homology domain of AKT1 in endometrial carcinomas.

BACKGROUND: The phosphatidylinositol 3'-kinase (PI3K)-AKT pathway is activated in many human cancers and plays a key role in cell proliferation and survival. A mutation (E17K) in the pleckstrin homology domain of the AKT1 results in constitutive AKT1 activation by means of localisation to the plasma membrane. The AKT1 (E17K) mutation has been reported in some tumour types (breast, colorectal, ovarian and lung cancers), and it is of interest which tumour types other than those possess the E17K mutation. METHODS: We analysed the presence of the AKT1 (E17K) mutation in 89 endometrial cancer tissue specimens and in 12 endometrial cancer cell lines by PCR and direct sequencing. RESULTS: We detected two AKT1 (E17K) mutations in the tissue samples (2 out of 89) and no mutations in the cell lines. These two AKT1 mutant tumours do not possess any mutations in PIK3CA, PTEN and K-Ras. INTERPRETATION: Our results and earlier reports suggest that AKT1 mutations might be mutually exclusive with other PI3K-AKT-activating alterations, although PIK3CA mutations frequently coexist with other alterations (such as HER2, K-Ras and PTEN) in several types of tumours.

Post-operative oral contraceptive use reduces the risk of ovarian endometrioma recurrence after laparoscopic excision.

BACKGROUND: The aim of this study was to evaluate the impact of post-operative oral contraceptives (OCs) use on the rate of recurrence after laparoscopic excision of ovarian endometrioma. METHODS: In May 2005, we introduced a 'post-operative OC recommendation' for patients treated with laparoscopic excision of endometrioma. That is, at the time of the operation, we provided each patient with information about OC, known and possible benefits and risks and let her decide whether to take OC. A retrospective cohort study included 87 patients who underwent a laparoscopy after May 2005. The endometrioma recurrence rate at 24 months was compared between those who used OC for the entire follow-up period OC (n = 34) and all of the others (n = 53). We also performed logistic regression analysis to identify variables associated with recurrence. A before-after study included another 224 patients who underwent a laparoscopy before May 2005 and compared the recurrence rate before and after introduction of the 'post-operative OC recommendation'. RESULTS: The recurrence rate in those who used OC for the entire period was significantly lower than in the 'others' group (2.9 versus 35.8%, relative risk 0.082, 95% CI 0.012-0.58, P < 0.001). Post-operative OC was determined as an independent variable associated with lower recurrence (OR 0.054, 95% CI 0.007-0.429, P < 0.001). The overall recurrence rate in patients who underwent laparoscopy after the introduction of the 'post-operative OC recommendation' was significantly lower than that in patients who received laparoscopy before the introduction (18.6 versus 33.1%, relative risk 0.56, 95% CI 0.32-0.97, P < 0.05). CONCLUSIONS: Post-operative OC use reduces the risk of ovarian endometrioma recurrence after laparoscopic excision. This information will help in appropriate planning of pre- and post-operative management.

Mitosis-specific phosphorylation of vimentin by protein kinase C coupled with reorganization of intracellular membranes.

Using two types of anti-phosphopeptide antibodies which specifically recognize vimentin phosphorylated by protein kinase C (PKC) at two distinct PKC sites, we found that PKC acted as a mitotic vimentin kinase. Temporal change of vimentin phosphorylation by PKC differed form changes by cdc2 kinase. The mitosis-specific vimentin phosphorylation by PKC was dramatically enhanced by treatment with a PKC activator, 12-O-tetradecanoylphorbol-13-acetate (TPA), while no phosphorylation of vimentin by PKC was observed in interphase cells treated with TPA. By contrast, the disruption of subcellular compartmentalization of interphase cells led to vimentin phosphorylation by PKC. Cytoplasmic and nuclear membranes are fragmented and dispersed in the cytoplasm and some bind to vimentin during mitosis. Thus, targeting of activated PKC, coupled with the reorganization of intracellular membranes which contain phospholipids essential for activation, leads to the mitosis-specific phosphorylation of vimentin. We propose that during mitosis, PKC may phosphorylate an additional subset of proteins not phosphorylated in interphase.

Low-dose estradiol for climacteric symptoms in Japanese women: a randomized, controlled trial.

OBJECTIVES: To investigate two different doses of oral estradiol to reduce the number of hot flushes in Japanese women with climacteric symptoms. METHODS: Women (n = 211) aged 40-64 years who had experienced natural menopause or bilateral oophorectomy, with > or = three moderate/severe hot flushes per day in the week before study, were randomized to receive micronized estradiol (E2) 0.5 or 1.0 mg or placebo once daily for 8 weeks. The primary efficacy endpoint was percentage change in mean daily number of hot flushes over 7 days from baseline to final examination. RESULTS: Percentage change in mean daily number of hot flushes at final examination was similar for E2 0.5 mg and E2 1.0 mg (-79.58 +/- 28.29% vs. -82.49 +/- 25.31%, p = 0.555) but was significantly lower with placebo (-57.89 +/- 34.15%, p < 0.001 vs. E2, both doses). There was no significant difference in number of treatment-related adverse events occurring in the E2 0.5 and 1.0 mg groups (25% and 36.6%, respectively). The higher E2 dose showed more pronounced effects on symptom severity. CONCLUSIONS: The dose of 0.5 mg/day was effective as the oral E2 starting dose for treatment of hot flushes in Japanese women.

Parafibromin tumor suppressor enhances cell growth in the cells expressing SV40 large T antigen.

Parafibromin (PF) is a 531-amino acid protein encoded by HRPT2, a putative tumor suppressor gene recently implicated in the autosomal-dominant hyperparathyroidism-jaw tumor familial cancer syndrome and sporadic parathyroid carcinoma. To investigate effects of PF's overexpression on cell proliferation, we performed assays in four different cell lines. The transient overexpression of PF inhibited cell growth in HEK293 and NIH3T3 cells, but enhanced cell growth in the SV40 large T antigen-expressing cell lines such as 293FT and COS7 cells. In 293FT cells, PF was found to interact with SV40 large T antigen and its overexpression promoted entry into the S phase, implying that the interaction enhanced progression through the cell cycle. The tumor suppressor protein PF acts as a positive regulator of cell growth similar to an oncoprotein in the presence of SV40 large T antigen.

Effect of late evening snack with rice ball on energy metabolism in liver cirrhosis.

OBJECTIVE: This study investigates the effects of a late evening snack (LES), of 200 kcal of rice ball, on energy metabolism in cirrhotic patients. Impaired nutritional metabolism has been associated with cirrhosis, and frequent intake of small meals may prevent early-onset starvation, and maintain nourishment in these patients. SUBJECTS: Twenty-one cirrhotic patients and 26 control subjects (Control) were recruited for this study. Patients were subsequently treated by LES (LC-LES) and by a non-LES regimen (LC-NLES). METHOD: Resting energy expenditure and respiratory quotient (RQ) were assessed by indirect calorimetry at 0830, 1130 and 1430. Blood glucose and non-esterified fatty acids (NEFA) were measured just before the energy metabolism measurements. The regular diet included three major meals and LES, at 0900, 1200, 1800 and 2100, respectively. The Control and LC-NLES groups received only the major meals, whereas the LC-LES group received three meals plus 200 kcal LES for 7 days. There was no difference in the total energy intake among Control, LC-NLES and LC-LES groups. RESULTS: Respiratory quotient in LC-NLES was significantly lower than that of Control at 0830. Respiratory quotient value in LC-LES significantly elevated from that in LC-NLES. The RQ values did not differ among Control, LC-NLES and LC-LES at 2 h after the meal (1130 and 1430). Non-esterified fatty acids in LC-LES were lower than that in LC-NLES after overnight fasting. CONCLUSIONS: The ingestion of a 200 kcal rice ball LES can improve the nutritional metabolism in cirrhotic patients.

3-D fractal tumor growth of epithelial ovarian cancer.

PURPOSE: A fractal is a shape made of parts similar to the whole. Our objective was to determine whether surface growth patterns in malignant epithelial ovarian tumors are 3-D fractal, and if the mean fractal dimension differs according to histologic types. METHODS: After the images of photographs of 139 resected malignant epithelial ovarian tumors were digitized, the fractal dimensions of surface of solid portions were measured using 3-D fractal analysis software. RESULTS: The mean fractal dimensions of the surface of a solid area of tumor in serous, mucinous, endometrioid, and clear cell adenocarcinoma were 2.320, 2.224, 2.229, and 2.298, respectively. Those of serous and mucinous cystadenoma of low malignant potential (LMP) were 2.398 and 2.282, respectively. These values were significantly greater than the topological dimension of a surface (= 2). The mean fractal dimensions of a solid area of tumor inside the cyst for serous, mucinous, endometrioid, and clear cell carcinoma were 2.347, 2.223, 2.228, and 2.310, respectively. The values for serous and mucinous cystadenoma of LMP were 2.398 and 2.282, respectively. CONCLUSION: This study shows that the surface of a solid area of malignant epithelial ovarian tumors has a 3-D fractal structure, and the mean fractal dimension may differ according to histologic types.

No evidence of correlation between polymorphism at codon 72 of p53 and risk of cervical cancer in Japanese patients with human papillomavirus 16/18 infection.

Human papillomavirus (HPV)-16 and -18 encode E6 oncoprotein, which binds to and induces degradation of the tumor suppressor protein p53. A common polymorphism of p53, encoding either proline or arginine at position 72, affects the susceptibility of p53 to E6-mediated degradation in vivo; Caucasian women homozygous for arginine 72 reportedly are about seven times more susceptible to HPV-associated carcinoma of the cervix than heterozygotes. To examine whether arginine 72 could be a risk factor for HPV-associated cervical carcinomas in the Japanese population, we used the same PCR-based assay to analyze p53 genotypes of HPV-positive invasive cervical carcinomas from 103 Japanese women versus 110 control samples. Inasmuch as we detected no significant difference in the frequencies of proline or arginine alleles between the two groups, p53 polymorphism at residue 72 does not seem to be involved in the development of HPV-associated cervical carcinomas in women of Japanese ethnicity.

Growth suppression of human ovarian cancer cells by adenovirus-mediated transfer of the PTEN gene.

A tumor suppressor gene on chromosome 10q23, PTEN, encodes a phosphatidylinositol phosphatase that antagonizes activation of the phosphatidylinositol 3'-kinase-mediated pathway involved in cell growth. A gene encoding the catalytic subunit of phosphatidylinositol 3'-kinase (PIK3CA) is frequently activated in ovarian cancers; therefore, overexpression of the PTEN product through gene transfer might be an effective strategy for treating ovarian cancers. To test the potential for this type of gene therapy, we constructed a recombinant adenovirus encoding wild-type PTEN and examined its effects on nine cell lines derived from human ovarian carcinomas. Transduction of the PTEN gene significantly inhibited growth of six of these cell lines compared with infection with virus alone, and the degree of inhibition correlated with the efficiency of gene transfer as determined by beta-galactosidase assay. Results of flow cytometry suggested that the observed effects were mediated by two mechanisms, apoptosis and/or arrest in the G1 phase of the cell cycle, and that high adenoviral transduction efficiency of cells was associated with induction of apoptosis. We also found that the level of transcription of Integrin alpha(v) in ovarian cancer cells correlated with the efficiency of transduction (P = 0.014) and with the degree of growth inhibition after PTEN gene transfer (P = 0.009). These findings carry significant implications for adenovirus vector-based PTEN gene therapies for ovarian cancers.

Studies on the induction of cyclooxygenase isozymes by various prostaglandins in mouse osteoblastic cell line with reference to signal transduction pathways.

A mouse osteoblastic cell line MC3T3-E1 has a cyclooxygenase enzyme, and produces prostaglandin E2. When the cells were cultured in the presence of iloprost (a stable analogue of prostacyclin) or prostaglandin E1 or F2 alpha, the activity of cyclooxygenase increased in a dose- and time-dependent manner. The increase of the enzyme activity was attributed mostly to the cyclooxygenase isoform-2 because immunoprecipitation using an anti-cyclooxygenase-2 antibody removed the majority of the cyclooxygenase activity from the solubilized enzyme fraction, and the corresponding activity was detected in the immunoprecipitant. In addition, there was a marked increase in the cyclooxygenase-2 protein which was demonstrated by Western blotting. As analyzed by Northern blotting, the cyclooxygenase-2 mRNA increased and reached a maximum 1 and 3 h after the addition of iloprost and prostaglandin F2 alpha (about 15- and 60-fold increase), respectively, whereas the cyclooxygenase-1 mRNA increased slowly and only by about 3-fold. Iloprost and prostaglandin E1 stimulated the production of cAMP by 60-fold over the basal level, whereas the cAMP level was almost unchanged by prostaglandin F2 alpha. In contrast, prostaglandin F2 alpha stimulated IP3 production more efficiently than iloprost and prostaglandin E1. These results suggest that the stimulated syntheses prominently of cyclooxygenase-2 and to a lesser extent of cyclooxygenase-1 are mediated by at least two distinct signal transduction pathways involving the cAMP-synthesis stimulated by iloprost and prostaglandin E1 and the phosphoinositide turnover stimulated by prostaglandin F2 alpha.

Characteristic expression of GD1 alpha-ganglioside during lactation in murine mammary gland.

Cellular proliferation and differentiation in mammary gland are known to be significantly altered during pregnancy and subsequent lactation. To characterize the different stages of mammary gland during pregnancy and lactation, we analyzed the glycosphingolipid compositions in the mammary gland of DDD and ICR mice at several periods of pregnancy and lactation, and found that the ganglioside composition, but not neutral glycosphingolipids, was characteristically altered during the pregnancy and lactation periods. The concentrations of acidic glycosphingolipids, I3SO3-GalCer 1, GM3, GM1a, GM1b and GD1a, were reduced during the course of pregnancy and lactation. GD1 alpha (III6NeuAc alpha,IV3NeuAc alpha-Gg4Cer) was first detected at the mid-period of pregnancy (12 days of pregnancy for ICR mice), increased in concentration at the late-period of pregnancy (GD1 alpha concentration was 100 times higher at 18 days than that at 12 days of pregnancy), and was a major ganglioside comprising 60-70% of the total lipid-bound sialic acid in the mammary gland of ICR and DDD mice at the lactation period, indicating that expression of GD1 alpha is associated with the lactating mammary gland of mice. In fact, GD1 alpha was highly concentrated in the milk fat globule, in which it was a major component.

Characterization of the 5' flanking region of the human NPT-1 Na+/phosphate cotransporter gene.

To elucidate the expression and regulation of the human type I Na+/phosphate transporter gene (NPT-1), the 5' flanking region of the NPT-1 gene was cloned, and its nucleotide sequence and function were determined. A genomic clone that contained approximately 14.0 kb of the 5'-flanking region of the NPT-1 gene was isolated. A single transcription start site was located 104 base pairs (bp) upstream of the 3' end of exon 1. In addition to the sequence of the 5'-flanking region contained a sequence weakly homologous to a TATA box at position -41 to -36 and many transcriptional regulatory elements. Transient expression revealed that a 45-bp region of proximal to exon 1, which contained TATA-like sequence, was sufficient for promoting luciferase expression in OK-cells derived from opossum kidney proximal tubule.

Sequence, tissue distribution and developmental changes in rat intestinal oligopeptide transporter.

Complementary DNA clones encoding the rat PepT1 small-intestinal oligopeptide transporter were isolated from a jejunal library by cross-hybridization with a rabbit PepT1 cDNA probe. The cDNA sequence indicates that rat PepT1 is composed of 710 amino acids and shows 77% and 83% amino acid sequence identity with rabbit and human PepT1, respectively. Northern blot analysis detected rat PepT1 mRNA in the small intestine and kidney. Intestinal PepT1 mRNA levels were highest in 4-day old rats, and then decreased reaching the adult level by day 28 after birth. These results indicate that the expressions of PepT1 gene change markedly during development.

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.