The potential theragnostic (diagnostic+therapeutic) application of exosomes in diverse biomedical fields

Exosomes are membranous vesicles of 30-150 nm in diameter that are derived from the exocytosis of the intraluminal vesicles of many cell types including immune cells, stem cells, cardiovascular cells and tumor cells. Exosomes participate in intercellular communication by delivering their contents to recipient cells, with or without direct contact between cells, and thereby influence physiological and pathological processes. They are present in various body fluids and contain proteins, nucleic acids, lipids, and microRNAs that can be transported to surrounding cells. Theragnosis is a concept in next-generation medicine that simultaneously combines accurate diagnostics with therapeutic effects. Molecular components in exosomes have been found to be related to certain diseases and treatment responses, indicating that they may have applications in diagnosis via molecular imaging and biomarker detection. In addition, recent studies have reported that exosomes have immunotherapeutic applications or can act as a drug delivery system for targeted therapies with drugs and biomolecules. In this review, we describe the formation, structure, and physiological roles of exosomes. We also discuss their roles in the pathogenesis and progression of diseases including neurodegenerative diseases, cardiovascular diseases, and cancer. The potential applications of exosomes for theragnostic purposes in various diseases are also discussed. This review summarizes the current knowledge about the physiological and pathological roles of exosomes as well as their diagnostic and therapeutic uses, including emerging exosome-based therapies that could not be applied until now.

Development of a LC-MS/MS for Quantification of Venlafaxine in Human Plasma and Application to Bioequivalence Study in healthy Korean Subjects

A simple, rapid and selective liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) is developed and validated for quantification of venlafaxine in human plasma with simple liquid-liquid extraction step consisted of extraction with ether and dichloromethane for 10 min and mixing with 1 M sodium acetate in human plasma using fluoxetine as an internal standard (IS). The analyte are separated using an isocratic mobile phase consisted of acetonitrile and 5 mM ammonium formate (4/3, v/v) on a isocratic YMC hydrosphere C18 (2.0x50.0 mm, 3.0 microm) column and analyzed by MS/MS in the multiple reaction monitoring (MRM) mode using the transitions of respective [M+H](+) ions, m/z 278.2-->260.3 and m/z 310.1-->148.1 for quantification of venlafaxine and IS, respectively. The standard calibration curves showed good linearity within the range of 1.0-200.0 ng/mL (r2=0.9986, 1/chi2 weighting). The lower limit of quantification (LLOQ) was 1.0 ng/mL. The retention times of venlafaxine and IS were 0.6 min and 0.7 min that means the potential for the high-throughput potential of the proposed method. In addition, no significant metabolic compounds were found to interfere with the analysis. Acceptable precision and accuracy were obtained for the concentrations over the standard curve range. The validated method was successfully applied to bioequivalence study after 75-mg of venlafaxine sustained-release (SR) capsule in 24 healthy Korean subjects.

Overview of Therapeutic Drug Monitoring

Therapeutic drug monitoring (TDM) is the clinical practice of measuring specific drugs at designated intervals to maintain a constant concentration in a patient's bloodstream, thereby optimizing individual dosage regimens. It is unnecessary to employ TDM for the majority of medications, and it is used mainly for monitoring drugs with narrow therapeutic ranges, drugs with marked pharmacokinetic variability, medications for which target concentrations are difficult to monitor, and drugs known to cause therapeutic and adverse effects. The process of TDM is predicated on the assumption that there is a definable relationship between dose and plasma or blood drug concentration, and between concentration and therapeutic effects. TDM begins when the drug is first prescribed, and involves determining an initial dosage regimen appropriate for the clinical condition and such patient characteristics as age, weight, organ function, and concomitant drug therapy. When interpreting concentration measurements, factors that need to be considered include the sampling time in relation to drug dose, dosage history, patient response, and the desired medicinal targets. The goal of TDM is to use appropriate concentrations of difficult-to-manage medications to optimize clinical outcomes in patients in various clinical situations.

Relationship of Propranolol Pharmacokinetic Parameters with Portosystemic Shunt in CCl4-induced cirrhotic Rats / 대한간학회지

BACKGROUND: This study was designed to determine the relationship of propranolol pharmacokinetic parameters with portosystemic shunt in CCl4-induced cirrhotic rats. METHODS: Cirrhotic rats(n=6) were induced by intramuscular injection of CCl4 in olive oil(two time per weeks) for 12 weeks. Controls (n=6) were injected intramuscularly with the same dose of olive oil for 12 weeks. We evaluated the amount of portosystemic shunt by thallium-201 per rectal scintigraphy. After intravenous bolus injection of propranolol (2mg/kg) to rats, the serum propranolol concentrations were analyzed by a HPLC-fluorimetric detector system. Pharmacokinetic parameters such as C0, AUC, t(1/2(beta)), and CLp were determined in each group. Then, a small amount of heptic tissue was obtained and subjected to determination of the hepatic collagen content by quantitating 4-hydroxyproline and were inspected by microscope after hematoxylin and eosin stain. RESULTS: In liver biopsy, liver fibrosis progressed in CCl4-induced cirrhotic rats. The serum concentrations of propranolol were significantly (p < 0.01) elevated in CCl4-induced cirrhotic rats. Mean amount of 4-hydroxyproline, mean H/L ratio, and mean AUC in CCl4-induced cirrhotic rats was significantly (p < 0.01) higher than that in control rats. There was a relationship between AUC, H/L ratio, and amount of 4-hydroxyproline. CONCLUSION: H/L ratio may help in the selection of drug dosage (especially blood flow dependent drug) in pre-clinical studies for chronic liver disease during the drug development process.

Guidance for clinical evaluation of drugs used in the tretment of hepatitis / 대한내과학회지

No abstract available.

Effect of thyroid hormone on the alcohol dehydrogenase activities in rat tissues

The effects of thyroid hormone on hepatic and gastric alcohol dehydrogenase (ADH) activities (nM of NADH/min/mg of cytosolic protein) have been investigated in male Sprague Dawley rats treated with thyroxine (1 mg/kg, po) for 14 days. Whereas hepatic ADH activity in thyroxine-treated rats decreased by 61.3% of control rats (26.4 vs 43.2, p<0.001), gastric ADH activity increased by 262.9% of control rats (4.9 vs 1.9, p<0.001). As for the activities of the lung and kidney, thyroxine treatment did not produce any statistically significant changes. These data suggest that thyrotoxicosis causes a decrease of hepatic alcohol metabolism, and that the increase of gastric ADH activity in thyrotoxic rats can partly restore the first-pass metabolism of ethanol.

Changes of Propranolol Pharmacokinetic Parameters According to Hepatic Fibrotic Severity in CCl4-Treated Rats / 대한간학회지

BACKGROUND/AIMS: This study was designed to determine the effect of hepatic fibrotic severity on pharmacokinetics of propranolol in CCl4-treated rats. METHODS: 1 mL/kg of 10% CCl4 in olive oil was injected intramuscularly to rats twice weekly for 4, 6, 8 and 10 weeks, respectively (n=6). Control (n=6) was a sham-injected equal dose of olive oil for 10 weeks. After intravenous bolus injection of 2 mg/kg propranolol to rats, the serum propranolol concentrations were analyzed for 4 hours at various time points by a HPLC-fluorimetric system, and pharmacokinetic parameters such as C0, MRT, AUC, Vdss, t1/2( ) and CLp were determined. Then, a small amount of hepatic tissue was obtained and subjected to determination of the hepatic 4-hydroxyproline content, which confirmed the hepatic fibrotic severity. RESULTS: The serum concentrations of propranolol at 0.5, 1, 2 and 4 hours were significantly increased in CCl4-treated rats (p<0.01). In proportion to the duration of CCl4 treatment, C0 and AUC were significantly increased, and Vdss and CLp were significantly decreased (p<0.001). But MRT and t1/2( ) were not significantly changed. The hepatic 4-hydroxyproline content was gradually increased in CCl4-treated rats (p<0.001). CONCLUSION: Gradual changes in pharmacokinetic parameters of propranolol were seen to be dependent on the hepatic fibrotic severity. We suggest that gradual dosage modification, according to their hepatic fibrotic severity, is necessary for many drugs administered to patients with chronic liver disease.

Urinary N-acetyl--D-glucosaminidase and Malondialdehyde as a Markers of Renal Damage in Burned Patients

This study was aimed to evaluate renal dysfunction during three weeks after the burn injuries in 12 patients admitted to the Hallym University Hankang Medical Center with flame burn injuries (total body surface area, 20-40%). Parameters assessed included 24-hr urine volume, blood urea nitrogen, serum creatinine, creatinine clearance, total urinary protein, urinary microalbumin, 24-hr urinary N-acetyl--D-glucosaminidase (NAG) activity, and urinary malondialdehyde (MDA). Statistical analysis was performed using repeated measures ANOVA test. The 24-hr urine volume, creatinine clearance, and urinary protein significantly increased on day 3 post-burn and fell thereafter. The urine microalbumin excretion showed two peak levels on day 0 post-burn and day 3. The 24-hr urinary NAG activity significantly increased to its maximal level on day 7 post-burn and gradually fell thereafter. The urinary MDA progressively increased during 3 weeks after the burn injury. Despite recovery of general renal function through an intensive care of burn injury, renal tubular damage and lipid peroxidation of the renal tissue suggested to persist during three weeks after the burn. Therefore, a close monitoring and intensive management of renal dysfunction is necessary to prevent burn-induced acute renal failure as well as to lower mortality in patients with major burns.

The Pharmacokinetic Characteristics of Methylprednisolone in Korean Renal Transplant Recipients / 대한신장학회잡지

Glucocorticoids are usually given according to a standard dosing protocol regardless of individual difference. We evaluated the pharmacokinetic characteristics of methylprednisolone and the degree of interpatient variation in stable Korean renal transplant recipients during the period of 15-21 days after transplantation. This study included 23 renal transplant recipients, 13 males and 10 females, who received kidneys from living donors with stable graft function and without episode of acute rejection. On the study day at 8 A.M., 16.3mg of ethylprednisolone sodium succinate (i.v.) was administered to each patient instead of usual dose (20mg) of prednisolone (p.o.) after sampling of 7cc of baseline blood and additional blood samples were drawn after starting infusion. Plasma was separated and analyzed for methylprednisolone level using high performance liquid chromatography (HPLC) assay, and parameters for pharmacokinetics were calculated. There was significant interpatient variation in the pharmacokinetics of methylprednisolone in our patients group. There was no significant difference in the pharmacokinetic parameters between patients with and without side effects of steroid. Korean renal transplant recipients had higher volume of distribution than black renal transplant recipients; lower clearance than white renal transplant recipients; longer t1/2 than both black and white renal transplant recipients. Even if the number of patients included in this study was too small to reach conclusion, the differences in the pharmacokinetics of glucocorticoids do not seem to be a significant risk factor for side effects of steroid after transplantation. It may be necessary to individualize the dose of a glucocorticoid to achieve an optimal effect and also we need to establish a new steroid regimen protocol for Korean renal transplant recipients.