Physicochemical and structural properties of glycerin gel prepared using glycyrrhizic acid diethyl ester.

Glycyrrhizic acid diethyl ester (GZ-DE) was developed as a prodrug of glycyrrhizic acid (GZ), a hepatitis therapeutic drug. We fortuitously found that GZ-DE gels with glycerin selectively while searching for a safe solvent with which to dissolve GZ-DE. Based on this gelation, the aim of this study was to investigate the preparation of the gel and study the rheology, physicochemical and structural properties of the glycerin gel by differential scanning calorimeter (DSC), capillary electrophoresis (CEP), nuclear magnetic resonance (NMR), and small angle X-ray scattering (SAXS). The glycerin gel was prepared by the addition of at least 2.0% w/w GZ-DE. This gel did not flow at room temperature. After mixing glycerin and GZ-DE, a gel was formed after 2 days at 25°C or 3 h at 60°C. Glycerin gel containing 2.4% w/w GZ-DE provided the following results: 1) The glycerin gel exhibited creep at a constant stress of less than 10 Pa, but it is a fragile gel, showing Newtonian flow at 10 Pa stress. 2) Dynamic viscoelastic measurements showed that the elastic modulus (G') exceeds the viscous modulus (G''), indicating that glycerin gel has solid-like properties. 3) DSC showed a significant difference between the glass transition temperature of glycerin and glycerin gel. 4) CEP did not reveal a new compound in the glycerin gel. 5) NMR confirmed that glycerin gel is a physical gel. 6) SAXS measurements revealed that the glycerin gel has an oval-shaped basic frame (119 nm long and 65 nm wide).

A new method for producing urinary bladder hyperactivity using a non-invasive transient intravesical infusion of acetic acid in conscious rats.

INTRODUCTION: Animal models that closely resemble the pathophysiology of human overactive bladder are important for evaluating novel therapeutics to treat the disorder. We established a non-invasive hyperactive bladder model that is sensitive to anti-muscarinic drugs and without bladder inflammation. METHODS: Acetic acid solution was infused into the bladder for 5 min via the urethral orifice without any surgical procedures under isoflurane anaesthesia. After washing the bladder with saline, voiding frequency (VF) and total urine volume were determined for 9 h under conscious conditions. RESULTS: Infusion of a 0.5% acetic acid solution caused a significant increase in VF, without influencing total urine volume or inducing significant histopathological inflammatory alterations in the bladder urothelium. Oral administration of oxybutynin (3 and 10 mg/kg) significantly ameliorated increases in VF induced by 0.5% acetic acid. Infusion of 0.75% acetic acid induced intensive urinary inflammation and a decrease in total urine volume as well as an increase in VF. Oral treatment with oxybutynin (10 mg/kg) did not significantly improve the increased VF due to 0.75% acetic acid. Acetic acid (0.5%) infusion evoked bladder hyper-responsiveness whether applied at night or during the day. However, VF was increased more by the nighttime application of acetic acid, while there were no significant differences in basal levels of VF between daytime and nighttime. DISCUSSION: In this study, the non-invasive rat urinary hyperactive bladder model indicated minimizes the secondary effects of experimental procedures such as surgical operations and anesthesia on bladder function and is sensitive to oxybutynin. Thus, the model may be useful for investigating novel therapeutics for OAB treatment.

Histopathological study of time course changes in inter-renal aortic banding-induced left ventricular hypertrophy of mice.

The left ventricular hypertrophy (LVH) in response to pressure overload is an important risk factor in cardiac morbidity and mortality. To investigate the time course of histopathological alterations in the LVH in response to pressure overload, histopathological and immunohistochemical examination was performed using the aortic banding-induced mouse LVH model. Five-week-old male CD-1 mice were subjected to the inter-renal aortic banding. Major organs were sampled on 3, 10, 14, 21, 28 or 42 days after banding. Haematoxylin and eosin (H&E) staining, Masson's trichrome staining and immunohistochemistry for proliferating cell nuclear antigen (PCNA), alpha-smooth muscle actin (aSMA), ICAM-1, type I collagen and CD31 was performed and microscopically examined. Three days after aortic banding, acute inflammatory changes, such as macrophages/neutrophil infiltration and vascular wall injury were observed on/around the coronary arteries/arterioles of both ventricles. Intense ICAM-1 immunostaining was observed on the endothelium of the coronary arteries/arterioles. After day 10, vascular wall thickening and perivascular fibrosis was induced on the coronary arteries/arterioles. Immunohistochemistry for aSMA and PCNA demonstrated the proliferation of vascular smooth muscle cells in the media. After day 28, minimal cardiomyocyte hypertrophy was observed at the light microscope level. In the inter-renal aortic banding LVH model, histopathological alterations in early phase were mainly observed on coronary arteries/arterioles. These early phase alterations were thought to be hypertension-related changes in the coronary vasculatures. The cardiomyocyte hypertrophy observed in later phase was minimal at the light microscope level. These evidences would facilitate the understanding of pathophysiology of pressure overload LVH.