Evidence of d-phenylglycine as delivering tool for improving l-dopa absorption

<p>Abstract</p> <p>Background</p> <p><it>l</it>-Dopa has been used for Parkinson's disease management for a long time. However, its wide variety in the rate and the extent of absorption remained challenge in designing suitable therapeutic regime. We report here a design of using <it>d</it>-phenylglycine to guard <it>l</it>-dopa for better absorption in the intestine via intestinal peptide transporter I (PepT1).</p> <p>Methods</p> <p><it>d</it>-Phenylglycine was chemically attached on <it>l</it>-dopa to form <it>d</it>-phenylglycine-<it>l</it>-dopa as a dipeptide prodrug of <it>l</it>-dopa. The cross-membrane transport of this dipeptide and <it>l</it>-dopa via PepT1 was compared in brush-boarder membrane vesicle (BBMV) prepared from rat intestine. The intestinal absorption was compared by <it>in situ </it>jejunal perfusion in rats. The pharmacokinetics after i.v. and p.o. administration of both compounds were also compared in Wistar rats. The striatal dopamine released after i.v. administration of <it>d</it>-phenylglycine-<it>l</it>-dopa was collected by brain microdialysis and monitored by HPLC. Anti-Parkinsonism effect was determined by counting the rotation of 6-OHDA-treated unilateral striatal lesioned rats elicited rotation with (+)-methamphetamine (MA).</p> <p>Results</p> <p>The BBMV uptake of <it>d</it>-phenylglycine-<it>l</it>-dopa was inhibited by Gly-Pro, Gly-Phe and cephradine, the typical PepT1 substrates, but not by amino acids Phe or <it>l</it>-dopa. The cross-membrane permeability (Pm*) determined in rat jejunal perfusion of <it>d</it>-phenylglycine-<it>l</it>-dopa was higher than that of <it>l</it>-dopa (2.58 ± 0.14 vs. 0.94 ± 0.10). The oral bioavailability of <it>d</it>-phenylglycine-<it>l</it>-dopa was 31.7 times higher than that of <it>l-</it>dopa in rats. A sustained releasing profile of striatal dopamine was demonstrated after i. v. injection of <it>d</it>-phenylglycine-<it>l</it>-dopa (50 mg/kg), indicated that <it>d</it>-phenylglycine-<it>l</it>-dopa might be a prodrug of dopamine. <it>d</it>-Phenylglycine-<it>l</it>-dopa was more efficient than <it>l-</it>dopa in lowering the rotation of unilateral striatal lesioned rats (19.1 ± 1.7% vs. 9.9 ± 1.4%).</p> <p>Conclusion</p> <p>The BBMV uptake studies indicated that <it>d</it>-phenylglycine facilitated the transport of <it>l</it>-dopa through the intestinal PepT1 transporter. The higher jejunal permeability and the improved systemic bioavailability of <it>d-</it>phenylglycine-<it>l</it>-dopa in comparison to that of <it>l</it>-dopa suggested that <it>d-</it>phenylglycine is an effective delivery tool for improving the oral absorption of drugs like <it>l</it>-dopa with unsatisfactory pharmacokinetics. The gradual release of dopamine in brain striatum rendered this dipeptide as a potential dopamine sustained-releasing prodrug.</p

Granzyme G is expressed in the two-cell stage mouse embryo and is required for the maternal-zygotic transition

<p>Abstract</p> <p>Background</p> <p>Detailed knowledge of the molecular and cellular mechanisms that direct spatial and temporal gene expression in pre-implantation embryos is critical for understanding the control of the maternal-zygotic transition and cell differentiation in early embryonic development. In this study, twenty-three clones, expressed at different stages of early mouse development, were identified using differential display reverse transcription polymerase chain reaction (DDRT-PCR). One of these clones, which is expressed in 2-cell stage embryos at 48 hr post-hCG injection, shows a perfect sequence homology to the gene encoding the granzyme G protein. The granzyme family members are serine proteases that are present in the secretory granules of cytolytic T lymphocytes. However, the pattern of granzyme G expression and its function in early mouse embryos are entirely unknown.</p> <p>Results</p> <p>Upon the introduction of an antisense morpholino (2 mM) against granzyme G to knock-down endogenous gene function, all embryos were arrested at the 2- to 4-cell stages of egg cleavage, and the <it>de novo </it>synthesis of zygotic RNAs was decreased. The embryonic survival rate was dramatically decreased at the late 2-cell stage when serine protease-specific inhibitors, 0.1 mM 3,4-dichloroisocoumarin (3,4-DCI), and 2 mM phenyl methanesulphonyl fluoride (PMSF), were added to the <it>in vitro </it>embryonic culture medium. Survival was not affected by the addition of 0.5 mM EDTA, a metalloproteinase inhibitor.</p> <p>Conclusion</p> <p>We characterized for the first time the expression and function of <it>granzyme G </it>during early stage embryogenesis. Our data suggest that granzyme G is an important factor in early mouse embryonic development and may play a novel role in the elimination of maternal proteins and the triggering of zygotic gene expression during the maternal-zygotic transition.</p

Surgical treatment for thyrotoxic hypokalemic periodic paralysis: case report

Thyrotoxic hypokalemic periodic paralysis (THPP) is a rare, potentially life-threatening endocrine emergency. It is characterized by recurrent muscle weakness and hypokalemia. Because many THPP patients do not have obvious symptoms and signs of hyperthyroidism, misdiagnosis may occur. The published studies revealed that definitive therapy for THPP is control of hyperthyroidism by medical therapy, radioactive iodine or surgery, but the long-term post-operative follow-up result was not observed. We reported two cases of medically refractory THPP with recurrent paralysis of extremities and hypokalemia, and both were combined with thyroid nodules. Both patients were treated with total thyroidectomy; the pathology revealed that one is Graves' disease with thyroid papillary carcinoma, and the other is adenomatous goiter with papillary hyperplasia. No episode of periodic paralysis was noted and laboratory evaluation revealed normal potassium level during the post-operative follow up. Our experience suggests that total thyroidectomy by experienced surgeon is an appropriate and definite treatment for medically refractory THPP, especially in cases combined with thyroid nodules

Anatomical Variations of Recurrent Laryngeal Nerve During Thyroid Surgery: How to Identify and Handle the Variations With Intraoperative Neuromonitoring

Recurrent laryngeal nerve (RLN) palsy is the most common and serious complication after thyroid surgery. Visual identification of the RLN during thyroid surgery has been shown to be associated with lower rates of palsy, and although it has been recommended as the gold standard for RLN treatment, it does not guarantee success against postoperative vocal cord paralysis. Anatomical variations of the RLN, such as extra-laryngeal branches, distorted RLN, intertwining between branches of the RLN and inferior thyroid artery, and non-recurrent laryngeal nerve, can be a potential cause of nerve injury due to visual misidentification. Therefore, intraoperative verification of functional and anatomical RLN integrity is a prerequisite for a safe thyroid operation. In this article, we review the literature and demonstrate how to identify and handle the anatomical variations of the RLN with the application of intraoperative neuromonitoring in the form of high resolution photography, which can be informative for thyroid surgeons. Anatomical variations of the RLN cannot be predicted preoperatively and might be associated with higher rates of RLN injury. The RLN injury caused by visual misidentification can be rare if the nerve is definitely identified early with intraoperative neuromonitoring

Seismic behavior of pile in liquefiable soil ground by centrifuge shaking table tests

Dramatic failure of pile foundations caused by the soil liquefaction was founded and leading to many studies on the seismic behavior of pile. The failures were often accompanied with settlement, lateral displacement and tilting of superstructures. Therefore soil-structure interaction effects must be properly considered in the design of pile. Two centrifuge models were conducted by shaking table at an acceleration field of 80 g. The purpose of this study was to investigate the seismic response of piles attached with different tip mass and embedded in liquefied or non-liquefied deposits. From the results, it was found that the maximum bending moment of pile occurs at the depth of 4 m and 5 m for dry sand and saturated sand models, respectively. The more tip mass leads to the more permanent lateral displacement and the more residual bending moment

Growth and Characteristics of High-quality InN by Plasma- Assisted Molecular Beam Epitaxy

The high-quality InN epifilms and InN microdisks have been grown with InGaN buffer layers at low temperatures by plasma-assisted molecular beam epitaxy. The samples were analyzed using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and photoluminescence. The characteristics of the InN epifilms and InN microdisks were studied, and the role of InGaN buffer was evaluated