Transport of organic cationic drugs: effect of ion-pair formation with bile salts on the biliary excretion and pharmacokinetics.

More than 40% of clinically used drugs are organic cations (OCs), which are positively charged at a physiologic pH, and recent reports have established that these drugs are substrates of membrane transporters. The transport of OCs via membrane transporters may play important roles in gastrointestinal absorption, distribution to target sites, and biliary and/or renal elimination of various OC drugs. Almost 40 years ago, a molecular weight (Mw) threshold of 200 was reported to exist in rats for monoquaternary ammonium (mono QA) compounds to be substantially (e.g., >10% of iv dose) excreted to bile. It is well known that some OCs interact with appropriate endogenous organic anions in the body (e.g., bile salts) to form lipophilic ion-pair complexes. The ion-pair formation may influence the affinity or binding of OCs to membrane transporters that are relevant to biliary excretion. In that sense, the association of the ion-pair formation with the existence of the Mw threshold appears to be worthy of examination. It assumes the ion-pair formation of high Mw mono QA compounds (i.e., >200) in the presence of bile salts in the liver, followed by accelerated transport of the ion-pair complexes via relevant bile canalicular transporter(s). In this article, therefore, the transport of OC drugs will be reviewed with a special focus on the ion-pair formation hypothesis. Such information will deepen the understanding of the pharmacokinetics of OC drugs as well as the physiological roles of endogenous bile salts in the detoxification or phase II metabolism of high Mw QA drugs.

Comparison between conventional and protective one-lung ventilation for ventilator-assisted thoracic surgery.

Recent papers suggest protective ventilation (PV) as a primary ventilation strategy during one-lung ventilation (OLV) to reduce postoperative pulmonary morbidity. However, data regarding the advantage of the PV strategy in patients with normal preoperative pulmonary function are inconsistent, especially in the case of minimally invasive thoracic surgery. Therefore we compared conventional OLV (VT 10 ml/kg, FiO2 1.0, zero PEEP) to protective OLV (VT 6 ml/kg, FiO2 0.5, PEEP 5 cmH2O) in patients with normal preoperative pulmonary function tests undergoing video-assisted thoracic surgery. Oxygenation, respiratory mechanics, plasma interleukin-6 and malondialdehyde levels were measured at baseline, 15 and 60 minutes after OLV and 15 minutes after restoration of two-lung ventilation. PaO2 and PaO2/FiO2 were higher in conventional OLV than in protective OLV (P<0.001). Interleukin-6 and malondialdehyde increased over time in both groups (P<0.05); however, the magnitudes of increase were not different between the groups. Postoperatively there were no differences in the number of patients with PaO2/FiO2<300 mmHg or abnormalities on chest radiography. Protective ventilation did not provide advantages over conventional ventilation for video-assisted thoracic surgery in this group of patients with normal lung function.

Tissue-specific changes in mRNA expression of Abc and Slc transporters in murine pulmonary tuberculosis.

A pulmonary tuberculosis mouse model was used to assess the pharmacodynamic and pharmacokinetic characteristics of tuberculosis therapeutics. While membrane transporters play important roles in drug disposition and physiological homeostasis, their expressional changes and contribution have never been analysed in a tuberculosis animal model. The mRNA expression level of 20 Abc family transporters and 32 Slc family transporters in tuberculosis-infected mice were compared with those in naïve uninfected mice using real-time polymerase chain reaction (PCR). Mycobacterium tuberculosis infection induced many dramatic expression changes of families of both Abc transporters and Slc transporters at 4 and 8 weeks, as observed in the livers, kidneys, and intestines of test mice--and in a different mode, in the lungs and spleens as well. These changes were dependent on the tuberculosis progression with the tissue-specific manner, that is, in the lungs, the number of transporters of which the expression level changed due to M. tuberculosis infection had increased, and the magnitude of change also greater at 8 weeks, while in the spleen, the transcription of most transporters except Mrps had not changed or had recovered back to the same level of naïve transcription at 8 weeks. Understanding the expression changes of transporters will assist in setting up rational preclinical dosing plans through the ability to predict the pharmacokinetics of new anti-tuberculosis chemotherapeutics and, furthermore, will assist in the design of safer and more efficient drug regimens.

Decreased urinary secretion of belotecan in folic acid-induced acute renal failure rats due to down-regulation of Oat1 and Bcrp.

The effects of folic acid-induced acute renal failure on the renal excretion of belotecan were investigated in rats after intravenous administration. Both glomeruli and renal tubules were seriously damaged by folic acid-induced acute renal failure. The renal excretion clearance, CLr, of belotecan was significantly decreased by folic acid-induced acute renal failure. Furthermore, glomerular filtration rate and secretion clearance of the drug were dramatically decreased by folic acid-induced acute renal failure. In vivo renal uptake of belotecan was inhibited by p-aminohippurate, whereas renal excretion was inhibited by GF120918, but not by verapamil and bromosulphalein. This indicates that Oat1/3 and Bcrp are involved in the renal uptake and urinary excretion of belotecan, respectively. Both mRNA and protein levels of Oat1, Oat3 and Bcrp were significantly decreased in folic acid-induced acute renal failure rats. Based on the finding that belotecan is a substrate of OAT1 but not of OAT3, the decrease in CLr of belotecan in folic acid-induced acute renal failure could, therefore, mainly be attributed to the down-regulation of Oat1 and Bcrp, in addition to the decrease in glomerular filtration rate.

Development of a sustained-release recombinant human growth hormone formulation.

Recombinant human growth hormone (rhGH) therapy for short stature must be administered as a daily injection because of its poor bioavailability and short half-life. In the present study, a sustained-release formulation of rhGH (SR-rhGH), DA-3003, was prepared using double emulsion solvent evaporation with poly(D,L-lactide-co-glycolide) (PLGA), zinc oxide and hydroxypropyl-beta-cyclodextrin (HPCD) as the release modulator, stabilizer, and aggregation-prevention agent, respectively. After a single administration of DA-3003, the elevated concentration of rhGH in plasma was sustained for 14 days in rats and 28 days in monkeys. The plasma concentration of insulin-like growth factor-1 (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3), which are pharmacodynamic markers of rhGH administration, increased and remained elevated for approximately 28 days in monkeys. Monkeys administered DA-3003 did not develop antibodies to hGH, indicating safety of the SR-rhGH formulation comparable to that observed with daily rhGH injections (Growtropin II). There were no significant differences in efficacy between Growtropin II (daily dose of 5 microg/animal for 14 days) and DA-3003 (weekly dose of 35 microg/animal for 14 days with a dosing interval of a week) in hypophysectomized rats, as assessed by changes in body weight and the width of the tibial growth plate. These results show that a sustained-release rhGH formulation, DA-3003, has the potential to be used safely and efficaciously in a weekly dosing regimen.

HSV-1 amplicon viral vector-mediated gene transfer to human bone marrow-derived mesenchymal stem cells.

Human bone marrow-derived mesenchymal stem cells (BM-hMSCs) are nonhematopoietic stem cells that have the potential to differentiate into adipocytes, osteocytes and chondrocytes. Because of its propensity to migrate to the sites of injury and the ability to expand them rapidly, BM-hMSCs have been exploited as potential gene transfer vehicles to deliver therapeutic genes. Herein, we evaluated the feasibility of employing herpes simplex virus type I (HSV-1) amplicon viral vector as a gene delivery vector to BM-hMSCs. High transduction efficiencies were consistently observed in different isolates of BM-hMSCs following infection with HSV-1 amplicon viral vectors. Furthermore, we demonstrated that transduction with HSV-1 amplicon viral vector did not alter the intrinsic properties of the BM-hMSCs. The morphology and cellular proliferation of the transduced BM-hMSCs were not altered. Chromosomal stability, as confirmed by karyotyping and soft agar colony assays, of the transduced BM-hMSCs was not affected. Similarly, transduction with HSV-1 amplicon viral vectors has no effect on the pluripotent differentiation potential and the tumor tropism of BM-hMSCs. Taken together, these results demonstrated that BM-hMSCs could be transduced efficiently by HSV-1 amplicon viral vector in an 'inert' manner and thus enable strategies to express potential therapeutic genes in BM-hMSCs.

Tissue-specific regulation of malonyl-CoA decarboxylase activity in OLETF rats.

AIM: The intracellular concentration of malonyl-CoA, a key regulator of fatty acid oxidation, is determined both from its synthesis by acetyl-CoA carboxylase and from its degradation by malonyl-CoA decarboxylase (MCD). The aim of our study was to investigate the activity and mRNA expression of MCD under insulin resistance and after treatment with insulin sensitizers in different tissues. METHODS: We treated 18-week Otusuka Long-Evans Tokushima Fatty (OLETF) rats with pioglitazone (10 mg/kg/day) or metformin (300 mg/kg/day) for 8 weeks and determined the activity and mRNA expression of MCD in diabetic OLETF and non-diabetic Long-Evans Tokushima Otsuka (LETO) rats in myocardial and skeletal muscles, and in liver. RESULTS: The MCD activities of myocardial and skeletal muscles were remarkably reduced in OLETF rats compared with LETO rats (995 +/- 114 vs. 2012 +/- 359, 58 +/- 11 vs. 167 +/- 40 pmol/min/mg protein; p = 0.005 and p = 0.010). Surprisingly, after pioglitazone treatment, not after metformin, the MCD activities of myocardial and skeletal muscles (1906 +/- 320 and 259 +/- 44 pmol/min/mg protein) increased up to the levels in LETO rats. MCD mRNA expression in OLETF rats was also reduced in myocardial and skeletal muscles vs. LETO rats (p = 0.049 and p = 0.008) and was unchanged by pioglitazone or metformin treatment. In the liver, MCD activity and mRNA expression were similar in OLETF and LETO rats. CONCLUSION: Pioglitazone treatment restored MCD activity to non-diabetic level and improved the restrained fatty acid metabolism in myocardial and skeletal muscles caused by insulin-resistant diabetic status.

Inhibition of angiopoietin-1 expression in tumor cells by an antisense RNA approach inhibited xenograft tumor growth in immunodeficient mice.

Angiopoietin-1 (Ang1) is an angiogenic growth factor that functions through activation of its endothelium-specific tyrosine kinase receptor Tie2; it mediates the interaction between endothelial and surrounding cells to promote the remodeling, maturation and stabilization of blood vessels. Although Ang1 is expressed constitutively in many adult tissues, its role in tumor growth and metastasis is not clear. Here we describe experiments in which Ang1 expression was inhibited in HeLa cells by an antisense RNA approach. The modified HeLa cells produced significantly less Ang1 protein both in cultured cells and in tumors formed when these cells were injected into immunodeficient mice. The Ang1 antisense tumors grew much more slowly, with significantly reduced tumor angiogenesis compared with control tumors. Furthermore, they also had substantially increased tumor cell apoptosis and decreased tumor necrosis. Our results indicate that the perturbation of Ang1 expression in tumors could be an effective method to control tumor growth by inhibiting tumor angiogenesis and that antisense RNA is an efficient way to inhibit Ang1 protein production in tumor cells.

A case of localized persistent interstitial pulmonary emphysema.

Interstitial pulmonary emphysema is a well-documented complication of assisted mechanical ventilation in premature infants with respiratory distress syndrome. Localized persistent interstitial pulmonary emphysema (LPIPE) confined to a single lobe was incidentally presented in a 4-day-old female infant. This patient was a normal full-term baby with no respiratory distress symptom and no experience of assisted mechanical ventilation. Chest radiograph showed radiolucent area in right lower lobe zone, which needed differential diagnosis from other congenital lesions such as congenital cystic adenomatoid malformation and congenital lobar emphysema. CT scan showed irregular-shaped air cystic spaces and pathologically, cystic walls primarily consisted of compressed lung parenchyma and loose connective tissue intermittently lined by multinucleated foreign body giant cells.

Adaptive hypersensitivity to estradiol: potential mechanism for secondary hormonal responses in breast cancer patients.

Women with hormone dependent breast cancer initially respond to hormone deprivation therapy with tamoxifen or oophorectomy for 12-18 months but later relapse. Upon secondary therapy with aromatase inhibitors, patients often experience further tumor regression. The mechanisms responsible for secondary responses are unknown. We postulated that hormone deprivation induces hypersensitivity to estradiol. Evidence of this phenomenon was provided in a model system involving MCF-7 cells grown in vitro and in xenografts. To determine if the ER transcriptional process is involved in hypersensitivity, we examined the effect of estradiol on ER reporter activity, PgR, PS2, and c-myc as markers and found no alterations in hypersensitive cells. Next, we examined whether MAP kinase may be upregulated in the hypersensitive cells as a reflection of increased growth factor secretion or action. Basal MAP kinase activity was increased both in vitro and in vivo in hypersensitive cells. Proof of principle studies indicated that an increase in MAP kinase activity induced by TGFalpha administration caused a two- to three-fold shift to the left in estradiol dose response curves in wild type cells. Blockade of MAP kinase with PD98059 returned the shifted curve back to baseline. These data suggested that MAP kinase overexpression could induce hypersensitivity. To determine why MAP kinase was increased, we excluded constitutive receptor activity and growth factor secretion by the demonstration that the pure anti-estrogen, ICI 182780, could inhibit MAP kinase activation. We also excluded hypersensitivity to estradiol induced growth factor secretion, and thus MAP kinase activation, since estradiol stimulated MAP kinase at 24, 48, and 72 h at the same concentrations in hypersensitive as in wild type cells. Surprisingly, a series of experiments suggested that MAP kinase increased in hypersensitive cells as a result of estrogen activation via a non-genomic pathway. We examined the classical signal pathway in which SHC is phosphorylated and binds to SOS and GRB-2 to activate Ras, Raf, and MAP kinase. With 5-20 min of exposure, estradiol caused binding of SHC to the estrogen receptor, phosphorylation of SHC, binding of GRB-2 to SOS, and activation of MAP kinase. All of these affects could be blocked by ICI 182780. Taken together, these observations suggest that the cell membrane ER pathway may be responsible for upregulation of MAP kinase and hypersensitivity in cells adapted to estradiol deprivation.

Estradiol hypersensitivity and mitogen-activated protein kinase expression in long-term estrogen deprived human breast cancer cells in vivo.

Women with breast cancer who have responded to initial hormonal therapy frequently experience additional remissions upon further endocrine manipulation. We postulate that hypersensitivity to estradiol (E2) may serve as a mechanistic explanation for these secondary responses. We previously provided evidence of hypersensitivity using an in vitro breast cancer model system and demonstrated the role of mitogen-activated protein kinase (MAP kinase) in the process of adaptation to long-term estradiol deprivation. In the present study, we wished to demonstrate that hypersensitivity to E2 could occur under more complex in vivo conditions and that MAP kinase activation is enhanced under these circumstances. We used an MCF-7 breast cancer model system involving long-term estradiol deprived (LTED) cells to produce xenografts in nude mice and an E2 clamp method to precisely control sex steroid levels. The E2 clamp was designed to maintain plasma E2 at a series of doubling doses from 1.25 pg/ml to 20.0 pg/ml in oophorectomized nude mice. As evidence of the validity of the clamp method, a uterine weight bioassay revealed an excellent, linear dose-response relationship between the predicted level of plasma E2 and stimulation of uterine weight. As evidence of hypersensitivity, we found that LTED xenograft tumors grew to a greater extent than wild-type in response to E2 concentrations of 1.25 pg/ml (P = 0.003) and 2.5 pg/ml (P = 0.0002). At the 10.0 and 20.0 pg/ml plasma concentrations, the LTED tumors were stimulated to a lesser extent than the wild-type. This pattern of increased growth at lower concentrations and reduced growth vs. the wild-type at higher concentrations mimics closely the pattern seen for LTED cells in vitro. All LTED cell tumors exhibited enhanced activation of MAP kinase ranging from 18 to 25%, and E2 did not increase this further. In contrast, E2 caused a linear increase in the percentage of activated MAP kinase positive cells (P < 0.0001) in wild-type tumors from basal levels of 2.66% to maximal levels of 6.40%. These observations suggest a dynamic interplay whereby activation of MAP kinase renders cells more sensitive to the proliferative effects of E2. The precise mechanisms for this interplay are unknown but, when further understood, could potentially provide insight into approaches to prevent the evolution of tumors to a hormone insensitive state.

Segregation of steroid receptor coactivator-1 from steroid receptors in mammary epithelium.

Steroid receptor coactivator-1 (SRC-1) family members interact with steroid receptors, including estrogen receptor alpha (ERalpha) and progesterone receptor (PR), to enhance ligand-dependent transcription. However, the expression of ERalpha and SRC-1 was found to be segregated in distinct subsets of cells within the epithelium of the estrogen-responsive rat mammary gland. This finding was in contrast to the finding for the stroma, where significant numbers of cells coexpressed ERalpha and SRC-1. Treatment of animals with estrogen induced PR expression in the ERalpha-expressing mammary epithelial cells in the absence of detectable SRC-1 and did not affect the segregated pattern of SRC-1 and ERalpha expression. PR was neither expressed nor induced by estrogen treatment in stroma, despite the coexpression of ERalpha and SRC-1. These results suggest that SRC-1 is not necessary for ERalpha-mediated induction of PR in mammary epithelial cells and is also not sufficient for PR induction in stromal cells expressing both ERalpha and SRC-1. Furthermore, the expression of SRC-1 in a subpopulation of mammary epithelial cells distinct from those expressing ERalpha or PR raises the possibility that SRC-1 has cell type-specific functions other than simply to act as coactivator for ERalpha or PR in the mammary epithelium.

A case of fatal hemolytic disease of the newborn associated with-D-/-D-phenotype.

-D- is a rare haplotype that determines D without C, c, E or e, and exalted D activity. The extremely rare homozygote propositi (-D-/-D-) are usually ascertained through their immune antibodies, anti-Rh17 (Hro), which react with red cells of all common Rh phenotypes. The authors experienced the first case in Korea of a woman with -D- phenotype. She had a history of spontaneous abortion, therapeutic termination and red cell transfusion, and at her third pregnancy she delivered a baby with severe hemolytic disease of the newborn. In spite of intensive medical intervention, the baby died of hydrops fetalis. An immune antibody to high incidence Rh antigen, namely anti-Rh17(Hro), was demonstrated in the woman's serum. A family study revealed that the -D- gene complex was present in all its members and one of the woman's sisters was also -D- homozygote. In the serum of this sister, anti-Rh17(Hro) was also present.

Clonal expansion of CD8+ T cells in Kawasaki disease.

Kawasaki disease (KD) is the major cause of acquired heart disease in children. KD is suspected of being an infectious disease, but the etiology has not yet been clarified. Immunologically, the disease is associated with the activation of T cells, monocytes, and macrophages resulting in highly elevated levels of several cytokines. Recently, expansions of T cells expressing TCRBV2 and TCRBV8 chains have been reported, and this suggests the involvement of a superantigen in the pathogenesis of KD. To address the role of a superantigen in KD, we investigated clonal expansion of T cells by estimating the complementarity-determining region 3 size profile among T cells expressing TCRBV1, TCRBV2, TCRBV4, TCRBV5, TCRBV8, TCRBV14, TCRBV16, TCRBV17, TCRBV18, and TCRBV20 chains during acute KD, during subacute KD, and during the long term follow-up period. During the acute phase of KD, several clonal expansions were found mainly in the CD8+ T cells that disappeared during the long term follow-up period. Our data suggest that the conventional Ags rather than a superantigen were involved in the pathogenesis of acute KD.