A case of persistent atrial standstill.

A case of persistent atrial standstill is described. The criteria for diagnosing atrial standstill are separated into two categories: the lack of electrical atrial activity and the lack of mechanical atrial activity. Echocardiography of the anterior mitral leaflet is to be used as one of the noninvasive methods for the diagnosis of the lack of mechanical atrial activity.     

Effects of 2-methyl-1,4-naphtoquinone (menadione) on cellular signaling in RBL-2H3 cells

Reactive oxygen species (ROS) are produced in various cells and affect many biologic processes. In this study, we examined the effects of 2-methyl-1,4-naphtoquinone (menadione; vitamin K3) on signal transduction in mast cells. Several lines of evidence suggest that H2O2 affects the antigen-induced responses in mast cells but its mechanism is not clearly understood. Unlike H2O2, menadione produces ROS only inside cells. Thus, it is possible to investigate the effects of ROS produced intracellularly. Pretreatment of mast cells (RBL-2H3) with menadione inhibited exocytotic secretion (degranulation) induced by antigen stimulation dose dependently. Menadione also inhibited the intracellular Ca2+ increase induced by antigen stimulation. Menadione did not inhibit the Ca2+ increase due to Ca2+ release from the intracellular calcium store in the absence of extracellular Ca2+, but inhibited the Ca2+ influx from the extracellular medium. These results suggest that reactive oxygen generated inside RBL cells by menadione inhibited degranulation by decreasing Ca2+ influx through the store operated Ca2+ channel on the plasma membrane.     

High-performance liquid chromatographic-mass spectrometric determination of methamphetamine and amphetamine enantiomers, desmethylselegiline and selegiline, in hair samples of long-term methamphetamine abusers or selegiline users

We devised a highly sensitive method for simultaneously determining methamphetamine (MA) and amphetamine (AP) enantiomers, desmethylselegiline (DMSG) and selegiline (SG), in human hair using a derivatization technique and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). MA and AP enantiomers and DMSG were effectively converted to trifluoroacetic acid (TFA) derivatives, and the sensitivity of MA and DMSG increased five times over compared with that of free bases. The TFA derivatives of each compound were stable within one week in a stock solution of methanol or for 24 h in the HPLC mobile phase (mixture of methanol and ammonium formate buffer). Each compound was well separated, and calibration curves were linear in the concentration range 0.04-40 ng/mg for MA enantiomers, SG and DMSG, and 0.2-40 ng/mg for AP enantiomers. The accuracy and precision of the method were evaluated, and relative standard deviations were within 7%. Our method was successfully applied to hair samples obtained from long-term MA abusers and SG users. (+)-MA and (+)-AP were detected from three MA abusers at concentrations of 0.79-20.85 and 0.04-3.30 ng/mg, respectively. On the other hand, (-)-MA, (-)-AP, DMSG, and SG were detected in three SG users at concentrations of 2.48-9.05, 0.72-3.10, 0.12-0.59, and 0-0.04 ng/mg, respectively. Based on our obtained data, discrimination of MA abusers from SG users was considered to be possible by comparing optical isomers of MA and AP, the existence of DMSG and/or SG, and the concentration ratio of AP to MA in hair samples.     

Renoprotective effects of tea catechin in streptozotocin- induced diabetic rats

Tea catechins, a class of flavonoids, are suggested to have biological effects, possibly mediated through their antioxidative properties. Recent data indicated that tea catechins suppressed proliferative changes in glomeruli and inhibited the development of glomerulosclerosis in partially nephrectomized rats. We thus sought to determine whether tea catechins may protect against renal dysfunction in streptozotocin-induced diabetic rats. Four groups of male Sprague-Dawley rats (n=11–15 per group), with and without streptozotocin-induced diabetes, were treated with and without catechins (5 mg/day) administered in the drinking water for 12 weeks. At the end of the treatment period, 24-hour urinary albumin excretion rate (AER), serum lipid peroxides as thiobarbituric acid reactive substrates (TBARS) and blood pressure were measured. Renal glomerular volume and interstitial fibrosis were assessed morphologically. Albuminuria developed progressively in untreated diabetic rats, resulting in a mean AER of 559±124 (mean±SE) versus 63±7 μg/day/100 g body weight in non-diabetic rats at 12 weeks (P<0.001). Catechin treatment significantly reduced AER to 287±56 μg/day/100 g body weight in diabetic rats (P=0.017 versus untreated diabetic rats). Increased interstitial fibrosis in the kidney, observed in untreated diabetic rats, was completely normalized with catechin treatment. Serum levels of TBARS and blood pressure were comparable among the four groups. In conclusion, administration of tea catechin retards the progression of functional and morphological changes in the kidney of streptozotocin-induced diabetic rats.     

Non-effective Group with L-DOPA on Parkinsonism

(L-DOPA was supplied from Kyowa Hakko Co., Ltd. and from Dai-Ichi Pharmaceutical Co., Ltd.) An effectiveness of L-DOPA on 41 cases; 39 with idiopathic parkinsonism and 2 with olivopontocerebellar atrophy with parkinsonism, was observed. A comparison was made on several factors between 10 markedly and 9 non-effective cases. It was found that there is a relationship between the effectiveness of L-DOPA and an appearance of pyramidal signs which observed in all non-effective whereas only in two out of 10 markedly effective cases. Discussions were made on the idiopathic parkinsonisms which accompany pyramidal signs and are refractive to L-DOPA.     

Progression of Androgen-sensitive Mouse Tumor (Shionogi Carcinoma 115) to Androgen-insensitive Tumor after Long-term Removal of Testosterone

Shionogi Carcinoma 115 (SC115) is an androgen-sensitive transplantable mouse tumor. To study the mode of progression from androgen-sensitive to -insensitive tumor, cloned SC115 cells were serially cultured without androgen. Shortly after withdrawal of androgen, SC115 cells showed markedly decreased growth, but growth resumed gradually with loss of response to androgen and the cells 60 weeks after androgen removal [A(—)60 cells] grew faster than SC115 cells cultured in the presence of androgen. A(—)60 cells showed malignant phenotype with morphological changes and tumorigenicity in male and female mice. Although mRNA and binding capacity of androgen receptor were maintained, the cells after removal of androgen rapidly lost expression of mouse mammary tumor virus-related gene and the loss was irreversible in A(—)60 cells. The stimulating effect of basic flbroblast growth factor (bFGF) temporarily decreased, then recovered to the initial level after long-term androgen removal. This fluctuation of response to bFGF was accompanied with changes in the number of bFGF receptors and amount of bFGF-like substance(s) secreted. The substance(s) seemed to be an FGF-like growth factor different from known factors. It was concluded that progression of SC115 cells to androgen-insensitive ones under an androgen-deprived condition proceeded with adaptation by means of increases in production of an FGF-like growth factor and in binding capacity to this factor.