Seok Ju Park

Analysis of acamprosate in beagle dog plasma by LC-MS-MS.

A rapid, sensitive, and specific analytical method was developed and validated to quantify acamprosate calcium in beagle dog plasma. The method employs a single plasma protein precipitation, and the analytes are separated by chromatography on an Acquity UPLC HSS T3 column and analyzed by mass spectrometry in the multiple reaction monitoring (MRM) mode. The method has a chromatographic run time of 1.25 min and a linear calibration curve over the range 200–10000 ng/mL (r2 > 0.9994). The intra-day and inter-day accuracy and precision were within 10.0% for the analyte. Acamprosate was stable during all sample storage, preparation, and analytical periods. This method was employed in a pharmacokinetic study of an acamprosate 333 mg enteric-coated tablet in 8 male beagle dogs that received single 666 mg doses (333 mg × 2 tablets). The proposed method enables identification and quantification in pharmacokinetic studies of acamprosate in beagle dog plasma.

Investigation of the relationship between in vitro and in vivo release behaviors of acamprosate from enteric-coated tablets

Acamprosate calcium is a highly soluble drug with low permeability that is used to maintain abstinence in alcohol-dependent patients. The aim of this study was to investigate the relationship between in vitro and in vivo behaviors of acamprosate from enteric-coated tablets. The in vitro release behavior of acamprosate tablets in pH 6.8 buffer solution was determined in three dissolution conditions, 50 and 150 rpm (paddle method) and 180 rpm (basket method). The results of this in vitro experiment indicated that acamprosate tablets hardly disintegrated, and drug dissolution was retarded despite the extremely hydrophilic nature of the drug. A single dose (333 mg×2 tablets) of each formulation was orally administered to four beagle dogs under fasting conditions, and the pharmacokinetic parameters were calculated. The mean AUC0-48, Cmax, Tlag and Tmax for the two types of tablets ranged from 41.5–53.6 μg·h/mL, 4.3–4.5 μg/mL, 2.0–2.5 h and 3.8–4.0 h, respectively. In conclusion, it is suggested that retarded drug release from the tablets and the low drug permeability may result in poor absorption and erratic bioavailability of this drug in humans.

Angiotensinogen polymorphisms and post-transplantation diabetes mellitus in Korean renal transplant subjects.

Background: Post-transplant diabetes mellitus (PTDM) is a common and serious metabolic complication. Genetic polymorphisms of angiotensin-converting enzyme (ACE) and angiotensinogen (AGT) genes have been reported to be related to diabetes mellitus and insulin sensitivity; however, the role of these genes in the development of PTDM is not known. For this purpose, we investigated the association of ACE and AGT genetic polymorphisms with PTDM. Methods: A total of 302 subjects without previously diagnosed diabetes who had received kidney transplants were included. One ACE single nucleotide polymorphism (SNP) (rs4291) and two AGT SNPs (rs 699 and rs 4762) were genotyped from genomic DNA with direct sequencing. Results: PTDM developed in 49 (16.2%) of 302 subjects. Subjects in the PTDM were older than those in the non-PTDM. There was a significant difference between the two groups in tacrolimus use (p=0.03). Of the three SNPs, the rs4762 of the AGT gene was significantly associated with the development of PTDM in the dominant models (p = 0.03) after adjusting for age and tacrolimus usage. Conclusions: AGT gene rs4762 polymorphisms may serve as genetic markers for the development of PTDM. The exact molecular mechanisms still need to be clarified.

Association between a TGFBR2 Gene Polymorphism (rs2228048, Asn389Asn) and Acute Rejection in Korean Kidney Transplantation Recipients

Transforming growth factor-β (TGF-β) signaling transduction initiates TGF-β activation, resulting in activation of TGF-β receptor II (TGFBR2). Any quantitative and qualitative changes in TGFBR2 are expected to affect the TGF-β signaling pathway, which occupies a central position with respect to the regulation of cell growth, differentiation, apoptosis, immune reaction, angiogenesis and extracellular matrix formation. Recent studies have shown that TGF-β1 gene polymorphisms may confer susceptibility to early acute and chronic allograft rejection in kidney transplantation recipients. In this study, we assessed whether polymorphisms of the TGFBR2 gene were associated with susceptibility to kidney transplantation rejection. A total of 347 renal allograft recipients transplanted at three centers in Korea were analyzed. Three SNPs (rs764522, rs3087465, rs2228048) of the TGFBR2 gene were genotyped from genomic DNA with direct sequencing. Multiple logistic regression models (codominant, dominant, recessive, and log-additive) were performed to evaluate odds ratios (ORs), 95% confidence intervals (CIs), and p-values. A total of 63 patients (18%) developed acute rejection (AR). There were no significant differences in age, sex, number of HLA mismatches, cause of renal failure, or immunosuppressant regimen between the AR and non-AR group. The synonymous SNP rs2228048 was significantly associated with AR (p = 0.020 in recessive model, and p = 0.036 in log-additive model. The allele frequencies of rs2228048 were different between the AR and non-AR group (p = 0.026). These results suggest that the synonymous TGFBR2 gene SNP rs2228048 may be associated with the development of AR in Korean kidney transplantation recipients. Authors Yeong-Hoon Kim and Tae Hee Kim contributed equally to this work and are considered co-first authors.

Allopurinol-induced aplastic anemia in a patient with chronic kidney disease.

Aplastic anemia is a rare complication of allopurinol use. We report an unusual case of aplastic anemia associated with allopurinol therapy for hyperuricemia in a patient with chronic kidney disease. A 37-year-old female patient diagnosed with Stage III chronic kidney disease was admitted with pancytopenia. She had a history of taking allopurinol for 5 months. Her bone marrow showed extremely decreased cellularity (< 20%) and there was no malignant cell infiltration. She was free of infections, including parvovirus B19, cytomegalovirus and Epstein-Barr virus. These results suggested a diagnosis of aplastic anemia. Allopurinol was discontinued immediately and treatment with blood transfusions and prednisolone was begun. After 6 months, the bone marrow cellularity improved to approximately 70%. Recently, it was suggested that decreased activity of multidrug resistance P-glycoprotein may play a role in acquired aplastic anemia. So we measured the inhibitory effect of allopurinol and oxypurinol on P-glycoprotein activity. But neither allopurinol nor oxypurinol inhibited P-glycoprotein activity.

Computational Exploration for Lead Compounds That Can Reverse the Nuclear Morphology in Progeria

Progeria is a rare genetic disorder characterized by premature aging that eventually leads to death and is noticed globally. Despite alarming conditions, this disease lacks effective medications; however, the farnesyltransferase inhibitors (FTIs) are a hope in the dark. Therefore, the objective of the present article is to identify new compounds from the databases employing pharmacophore based virtual screening. Utilizing nine training set compounds along with lonafarnib, a common feature pharmacophore was constructed consisting of four features. The validated Hypo1 was subsequently allowed to screen Maybridge, Chembridge, and Asinex databases to retrieve the novel lead candidates, which were then subjected to Lipinskis rule of 5 and ADMET for drug-like assessment. The obtained 3,372 compounds were forwarded to docking simulations and were manually examined for the key interactions with the crucial residues. Two compounds that have demonstrated a higher dock score than the reference compounds and showed interactions with the crucial residues were subjected to MD simulations and binding free energy calculations to assess the stability of docked conformation and to investigate the binding interactions in detail. Furthermore, this study suggests that the Hits may be more effective against progeria and further the DFT studies were executed to understand their orbital energies.

Association studies of cytochrome P450, family 2, subfamily E, polypeptide 1 (CYP2E1) gene polymorphisms with acute rejection in kidney transplantation recipients.

Recent studies have shown that single‐nucleotide polymorphisms (SNPs) are associated with allograft rejection in kidney transplantation recipients. We evaluated the possible association between SNPs of the cytochrome P450, family 2, subfamily E, polypeptide 1 (CYP2E1) gene, and acute rejection (AR) among renal transplant patients in a Korean population. We conducted a case–control association study in 63 AR and 284 non‐AR kidney transplant recipients. The SNPs of CYP2E1 were genotyped by direct sequencing. Recipient sex (p = 0.023) and the use of tacrolimus (p = 0.017) were significantly different between the two groups. The use of mycophenolate mofetil (MMF) and antibody induction therapy was significantly lower in the AR group. Multiple logistic regression models (codominant, dominant, recessive, and log‐additive models) adjusted by sex and type of immunosuppressive regimens were applied to determine the odds ratios (ORs), 95% confidence intervals (CIs), and p‐values. The rs2515641 of CYP2E1 showed significant differences between the AR patient group and non‐AR group (p = 0.003, OR = 2.55, 95% CI = 1.37–4.75 in the codominant 1 model; p = 0.002, OR = 2.61, 95% CI = 1.43–4.77 in the dominant model; p = 0.0035, OR = 2.13, 95% CI = 1.29–3.50 in the log‐additive model). The allele of the rs2515641 SNP also showed a significant association (p = 0.004, OR = 1.99, 95% CI = 1.24–3.21). This study suggests that the CYP2E1 polymorphism may be related to the development of AR in Korean kidney transplantation recipients.

In Vitro/in Vivo relationship of gabapentin from a sustained-release tablet formulation: A pharmacokinetic study in the beagle dog

The aim of this study was to examine the in vitro/in vivo relationship of the drug release behavior of a sustained-release formulation of gabapentin. The immediate-release formulation was used as the reference formulation. The dissolution test was employed using pH 1.2, 4.0, or 6.8 buffer solution, or water, to determine the in vitro release behaviors of gabapentin tablets. Gabapentin was released completely within 1 h from the immediate-release tablet and released for 12 h from the sustained-release tablet. A single dose (600 mg) of each formulation was orally administered to four beagle dogs under fasted conditions, and the pharmacokinetic parameters were calculated. Although the sustained-release tablet did not disintegrate and had slow drug release characteristics, it showed similar pharmacokinetic parameters to the immediate-release tablet, which rapidly disintegrated and showed fast drug release. Thus, the in vivo release of gabapentin did not correlate with in vitro release of drug.

Fibrillary glomerulonephritis associated with Behçet's syndrome.

Fibrillary glomerulonephritis (FGN) is a rare cause of progressive renal dysfunction resulting in fibrillary deposits in the mesangium and/or glomerular basement membrane (GBM). Some case reports have shown FGN in patients with rheumatoid arthritis and other autoimmune diseases. This is the first case report of FGN in a patient with Behçet’s syndrome. The most common renal histological finding in Behçet’s syndrome is secondary amyloidosis. A 46-year-old woman with a 4-year history of Behçet’s syndrome was referred to the nephrology clinic with foamy urine with non-selective proteinuria (urine protein-to-creatinine ratio was 1400 mg protein/g creatinine) and microscopic hematuria. Serum and urine protein electrophoresis showed no evidence of monoclonal gammopathy. A renal biopsy was performed. Light microscopy showed mesangial widening and nodular expansion with hyaline deposits. Immunofluorescence microscopy revealed immunoglobulin M deposits in the mesangium. Congo red staining was negative. Electron microscopy showed fibrillary deposits on the GBM. Pathological findings were consistent with FGN. She had been taking 50 mg azathioprine and 3000 mg mesalazine per day for 4 years due to Behçet’s syndrome, so we did not add any other immunosuppressive agents or corticosteroids. Treatment of this glomerulopathy is not promising. It has been noted that none of the various approaches, including corticosteroid, plasmapheresis, and cytotoxic therapy, improves prognosis.

Novel virtual lead identification in the discovery of hematopoietic cell kinase (HCK) inhibitors: application of 3D QSAR and molecular dynamics simulation

Abstract High level of hematopoietic cell kinase (Hck) is associated with drug resistance in chronic myeloid leukemia. Additionally, Hck activity has also been connected with the pathogenesis of HIV-1 and chronic obstructive pulmonary disease. In this study, three-dimensional (3D) QSAR pharmacophore models were generated for Hck based on experimentally known inhibitors. A best pharmacophore model, Hypo1, was developed with high correlation coefficient (0.975), Low RMS deviation (0.60) and large cost difference (49.31), containing three ring aromatic and one hydrophobic aliphatic feature. It was further validated by the test set (r = 0.96) and Fisher’s randomization method (95%). Hypo 1 was used as a 3D query for screening the chemical databases, and the hits were further screened by applying Lipinski’s rule of five and ADMET properties. Selected hit compounds were subjected to molecular docking to identify binding conformations in the active site. Finally, the appropriate binding modes of final hit compounds were revealed by molecular dynamics (MD) simulations and free energy calculation studies. Hence, we propose the final three hit compounds as virtual candidates for Hck inhibitors.