Transport properties of nonsteroidal anti-inflammatory drugs by organic anion transporter 1 expressed in Xenopus laevis oocytes

Organic anion transporter 1 (OAT1) is the para-aminohippurate (PAH) transporter in the basolateral membrane of the proximal tubule. The present study investigated whether or not nonsteroidal anti-inflammatory drugs (NSAIDs) are transported by OAT1. All of the NSAIDs tested inhibited [14C]PAH uptake via OAT1 expressed in Xenopus laevis oocytes. Ibuprofen, indomethacin, salicylurate, and naproxen showed the strongest potency to inhibit [14C]PAH uptake (Ki approximately 2-10 microM); acetylsalicylate, salicylate, and phenacetin exhibited moderate potency (Ki approximately 300-400 microM), and acetaminophen (paracetamol) exhibited the weakest inhibitory potency (Ki approximately 2 mM). Radiolabeled acetylsalicylate, salicylate, and indomethacin were taken up by OAT1 and the uptake rate of these three NSAIDs was enhanced by the outwardly directed dicarboxylate gradient. The efflux of the preloaded [14C]PAH from the oocytes via OAT1 was trans-stimulated by PAH and glutarate added to the media. The addition of salicylate, acetylsalicylate, or salicylurate into the media also trans-stimulated the efflux of PAH, whereas indomethacin did not. The present study indicates that OAT1 is responsible for the renal uptake and secretion of NSAIDs.     

Metabolic disposition of 6-ethyl-3-(1H-tetrazol-5-yl)-chromone, a new antiallergic agent, in the rat, guinea-pig, rabbit, dog and monkey.

1. [14C]Ethyltetrazolylchromone ([14C]ETC) was promptly absorbed from the rat small intestine by the portal route. 2. The maximum plasma concn. of unchanged drug after oral administration (10 mg/kg) was highest in dogs (456 microgram/ml), followed by monkeys (287 microgram/ml), guinea-pigs (146 microgram/ml) and rats (55 microgram/ml), and lowest in rabbits (09 microgram/ml). The half-life of the drug in plasma varied with the species, ranging from 13 to 133 h. The drug was highly bound to plasma protein. In dogs and rats, the plasma 14C was predominantly the unchanged drug, whereas in guinea-pigs, rabbits and monkeys it was mainly metabolites. 3. At 10 min after oral administration of the drug to rats there was a wide distribution of the 14C in the tissues. At this time, the 14C concn. were the highest in stomach, followed by kidney, liver, plasma, heart and lung, and lowest in brain. 4. Almost all administered 14C was eliminated from the body in 72 h. The major route of excretion was via the urine except with guinea-pigs, in which animal the 14C was almost equally divided between urine and faeces. 5. only trace amounts of the unchanged drug were found in urine and bile. The major urinary metabolites were as follows: I (1-hydroxyethyl ETC), II (acetyl ETC), III (IIIa, 2-hydroxyethyl ETC) and IV (1,2-dihydroxyethyl ETC) in rats, I and VI (5-carboxymethylsalicylic acid) in guinea-pigs, I, III (IIIb, carboxymethyl ETC) and VII (ETC-N-1-glucuronide) in rabbits, I and VII in dogs, and I and IV in monkeys.     

Effect of CYP2D6 genotypes on the metabolism of haloperidol in a Japanese psychiatric population.

We investigated the effect of CYP2D6 genotypes on plasma levels of haloperidol (HAL) and reduced haloperidol (RHAL) in 88 Japanese schizophrenic inpatients being treated with HAL. Some subjects carrying CYP2D6*5 allele (CYP2D6*1/CYP2D6*5, CYP2D6*5/CYP2D6*10) showed extremely high concentrations of both HAL and RHAL, and the groups with CYP2D6*5 allele seemed to have higher plasma concentrations of HAL (1.14+/-0.69 ng/ml/mg) and RHAL (1.10+/-1.05 ng/ml/mg) than the other groups. Among those without CYP2D6*5 allele, there were no significant differences in plasma concentrations of HAL and RHAL between those without CYP2D6*10 allele (HAL=0.68+/-0.31 ng/ml/mg, RHAL=0.28+/-0.37 ng/ml/mg), those with one CYP2D6*10 (HAL=0.70+/-0.23 ng/ml/mg, RHAL=0.31+/-0.16 ng/ml/mg) and those with two CYP2D6*10 alleles (HAL=0.69+/-0.14 ng/ml/mg, RHAL=0.40+/-0.09 ng/ml/mg), although there was a tendency of higher plasma concentration of RHAL in those with two CYP2D6*10 alleles. At a lower daily dosage of HAL (<10 mg/day), the subjects with two or one CYP2D6*10 allele(s) showed significantly higher plasma concentrations of RHAL (0.43+/-0.23 ng/ml/mg, 0.34+/-0.16 ng/ml/mg) than those without CYP2D6*10 allele (0.18+/-0.16 ng/ml/mg). The results of this study indicate that CYP2D6*10 allele plays significant but modest role in HAL metabolism in Japanese; nevertheless, we should not lump CYP2D6*10 allele with CYP2D6*5 allele because these two mutated alleles seem to have different impacts in the metabolism of HAL.     

Developmental changes in multispecific organic anion transporter 1 expression in the rat kidney

BACKGROUND: The cDNA of the multispecific organic anion transporter 1 (OAT1) responsible for the tubular secretion of organic anions was recently isolated. In the current study, we investigated the developmental changes in OAT1 expression in the rat kidney. METHODS: Ontogenic expression of rat OAT1 was investigated by Northern blot, in situ hybridization, Western blot, and immunohistochemical analysis. In addition, para-aminohippurate (PAH) accumulation was measured using fetal, neonatal, and adult rat kidney slices. RESULTS: In Northern blot analysis, OAT1 was detected as early as on embryonic day 18 in the fetal kidney. The expression level of OAT1 mRNA increased remarkably just after birth (postnatal day 0). In situ hybridization revealed OAT1 expression on embryonic day 19. In both the fetal and neonatal kidneys, OAT1 mRNA was localized in a relatively deep region in the cortex. Western blot analysis detected OAT1 protein on embryonic day 20, and the expression level increased after birth. Immunohistochemical analysis did not reveal OAT1 staining in the fetal kidneys. A faint signal of OAT1 protein was detected on postnatal day 0; thereafter, the expression level increased. In the functional study using kidney slices, low but definite probenecid-sensitive PAH accumulation was noted in fetal rat kidney on embryonic day 20. After birth, probenecid-sensitive PAH uptake was increased. CONCLUSIONS: The present study consistently demonstrates the remarkable increase of OAT1 expression after birth, and the immature excretory capacity of the proximal tubules of the neonatal kidney can be attributed, at least in part, to the low expression level of OAT1.     

Breast cancer in Cowden's disease: a case report with review of the literature

We report a case of invasive breast cancer in a 62-year-old female patient with Cowden's disease. A left modified radical mastectomy was performed and histopathology of the tumor showed invasive ductal carcinoma, histological grade 3, without lymph node metastasis. The patient had a past history of endometrial cancer at 55 but did not have a family history of malignant disease. Goiter was palpable but aspiration cytology revealed no malignancy. There were several papillomas on the oral mucosa and multiple papillomatous lesions on the right femur. Barium X-ray and endoscopic examination revealed multiple, small, hyperplastic polypoid lesions on the esophagus, stomach and rectum. Histopathology of the biopsy specimens from the esophagus and stomach showed acanthotic squamous epithelium and foveolar hyperplastic polyps. The patient was followed up closely to monitor the thyroid lesions and polyposis of the digestive tract. A total of 12 breast cancer patients who also had Cowden's disease have been reported in Japan and these cases are reviewed in this report.      

Microinvasive breast carcinoma with extensive involvement of level III axillary lymph nodes: a case report

A 44-year-old woman presented with a right huge axillary mass. Both mammography and ultrasonography revealed a primary cancer of 2.8 cm maximum diameter in the right breast and metastases in the axillary lymph nodes, both being confirmed by aspiration cytology as ductal carcinoma. Right standard radical mastectomy with level III axillary lymph node dissection was carried out. Pathologically, the tumor was diagnosed as ductal carcinoma in situ with microinvasion (DCISM), histologic grade 3. The area of stromal invasion measured 1 mm at its widest point. Sixteen of the 17 resected axillary lymph nodes contained metastases, including six level III lymph nodes. Immunohistochemical studies of the tumor revealed overexpression of p53 protein, but not that of c-erbB-2 protein. The frequency of lymph node metastases from DCISM is reported to be very low. Therefore, the present case with extensive involvement of level III lymph nodes was unusual.      

Pregnancy complicated with Buerger's disease.

Buerger's disease is an inflammatory occlusive vascular disorder involving small- and medium-sized arteries in the distal extremities and is usually complicated with thrombophlebitis. Since Buerger's disease develops most frequently in men who smoke, pregnancy complicated with this disease is extremely rare. Only three pregnancies have been reported previously. All cases indicate that Buerger's disease worsens during pregnancy. However, anti-coagulant therapy appeared to be effective in this case. Accordingly, careful observation is mandatory in pregnancies complicated with Buerger's disease.     

Expression of a system L neutral amino acid transporter at the blood-brain barrier

Amino acid transport system L has been proposed to be one of the major nutrient transport systems at the blood-brain barrier. Using immunohistochemical analyses, a system L transporter LAT1 was shown to be expressed in the brain capillary endothelial cells in rats. Because LAT1 was coexpressed with 4F2 heavy chain which brings LAT1 to the plasma membrane, LAT1 is proposed to be functional in the plasma membrane of brain capillary endothelial cells. Both LAT1 and 4F2hc immunoreactivities were detected in a double line appearance surrounding endothelial cell nuclei, suggesting both proteins are present in the luminal and abluminal membranes. LAT1 is, thus, a blood-brain barrier system L transporter responsible for the permeation of aromatic or branched-chain amino acids and amino acid-related drugs such as L-DOPA.     

Anti-tumor effects of water-soluble propolis on a mouse sarcoma cell line in vivo and in vitro

The honeybee product propolis and its extracts are known to have biological effects such as antibiotic, anti-viral, anti-inflammatory and anti-tumor activities. This study was designed to investigate whether water-soluble propolis (WSP) inhibits tumor growth. The tumor cell line used was mouse sarcoma 180 (S-180), and its growth was determined in vitro and in vivo with exposure to different concentrations of WSP. The effects of WSP on tumor cells in vitro were evaluated by measuring the intracellular uptake of 3H-thymidine. 3H-thymidine uptake was inhibited in accordance with the concentration of WSP. The minimum concentration of WSP necessary for 3H-thymidine uptake inhibition was 1.0 microg/ml and uptake was suppressed to 88% of the level in non-treated cells at this concentration. In an experiment using tumor-bearing mice, oral administration of WSP was begun 24 hours after transplantation of S-180 cells. WSP was administered to the mice 5 times, every other day for 10 days. The doses were 320 mg/kg (10 mg/mouse) or 960 mg/kg (30 mg/mouse) of body weight. All mice were sacrificed 10 days after transplantation, and tumor growth was evaluated. The orally administered WSP significantly inhibited the growth of transplanted tumors (p < 0.05). Furthermore, histological findings revealed a significant reduction in mitotic cells and tumor invasion of the muscular tissue at both dose-levels of WSP.