cDNA cloning and sequence analysis of Xenopus laevis preproendothelin-1

Endothelin (ET)-like immunoreactivity has been observed not only in mammals, but also in amphibians. The biological actions of ET are similar in amphibians and mammals, and amphibian ET-related receptors have been cloned and characterized. The cDNA sequences of mature and precursor forms of ET-related peptides, however, have not been reported in any amphibian until now. To identify the ET-related peptides, we screened the Xenopus laevis intestine cDNA library using the rapid amplification of cDNA ends method and cloned cDNAs encoding preproendothelin-1. The deduced amino acid sequence of X. laevis preproendothelin-1 comprises 223 amino acids, including a putative signal sequence of 19 amino acids, a mature ET-1 of 21 amino acids, as well as big ET-1 and ET-1-like sequences. X. laevis ET-1 is identical to mammalian ET-1 as well as ET-1 peptide, recently purified from the stomach of the European green frog, Rana ridibunda. This is the first report describing the cDNA encoding preproendothelin-1 in an amphibian species.     

Expression of endothelial nitric oxide synthase is induced by estrogen with glycogen synthase 3beta phosphorylation in MCF-7 cells

The endothelial nitric oxide synthase (eNOS) gene is induced by a variety of extracellular signals and NOS plays a key role in many physiological as well as pathological processes, including tumorgenesis. Some studies showed a positive correlation between the level of NOS protein and progression of malignancy in human breast cancer. In this study, we examined eNOS mRNA expression in human breast cancer cell lines. MCF-7 cells, which showed an estrogen receptor positive phenotype, were treated with estradiol or LiCl, a selective inhibitor of glycogen synthase kinase (GSK)-3beta. Both estradiol and LiCl enhanced the expression of eNOS mRNA with the phosphorylation of GSK-3beta, but not Akt. The induction was completely suppressed by the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor LY294002, but not by PD98059, MEK-1 inhibitor nor rapamycin, p70S6 kinase inhibitor. We conclude that the estradiol-induced eNOS expression is modulated by PI3-kinase-dependent GSK-3beta pathway.     

Disorders caused by abnormalities of glucocorticoid receptors

Abnormalities of glucocorticoid receptors were assumed to cause resistance or hypersensitivity to glucocorticoid, while only glucocorticoid resistance has been described clinically. Patients with familial cortisol resistance have continuously elevated serum cortisol without any clinical manifestations of Cushing's syndrome due to hyposensitivity to cortisol in all tissues including the hypothalamus and the pituitary. Clinical symptoms of the disease are characterized by hypertension with hypokalemia and hyporeninemia, virilism in women, isosexual precocity in a boy and mild general fatigue. As the cause of the disease, a defect in glucocorticoid receptor affinity or binding capacity due to mutations in the glucocorticoid receptor gene has been reported. Another cause of the disease is the presence of heat labile glucocorticoid receptor. In 5 of 6 families with cortisol resistance reported so far, mutations of the glucocorticoid receptor gene have been demonstrated.     

Ureteral stricture developing after partial nephrectomy with a microwave tissue coagulator: case report

A 32-year-old man with a 1.7-cm tumor in the left kidney underwent laparoscopy-assisted partial nephrectomy. Although his postoperative course was uneventful, a 6-month postoperative CT scan showed hydronephrosis secondary to a severe stricture at the ureteropelvic junction. Heat injury to the urinary tract was strongly suspected. The use of microwave tissue coagulator for the tumor close to the renal sinus and excessive coagulation should be avoided to prevent heat-related complications.     

Effects of 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS) and chlorpromazine on NO3- transport via anion exchanger in erythrocytes: inertness of DIDS in whole blood

We examined the effects of chlorpromazine on NO(3)(-) transport between erythrocytes (RBCs) and extracellular fluid. Chlorpromazine (10 microg/ml) did not influence NO(3)(-) movement in both whole blood and RBC suspension. Though an anion exchanger (AE1) inhibitor DIDS (4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid, 100 microM) did not alter NO(3)(-) movement in whole blood, it inhibited the movement in a concentration-dependent manner in the RBC suspension. The inhibition was abrogated by plasma and albumin concentration-dependently. Our results indicated that chlorpromazine had no effect on NO(3)(-) transport through AE1 and that the inertness of DIDS on AE1 in whole blood is due to interference by albumin in plasma.     

Increased myocardial uptake of iodine-123 metaiodobenzylguanidine on delayed images, compared with early images, in patients with multiple system atrophy

We present 2 interesting cases of multiple system atrophy in which increased myocardial iodine-123 metaiodobenzylguanidine uptake was observed on delayed images (3 hours after injection) compared with early images (15 minutes after injection). These findings have not been previously described. The duration of symptoms was less than 1 year in both these patients. The mechanism responsible for these findings is not clearly understood, but could be related to the pathophysiological changes in the early stage of multiple systemic atrophy.     

Quantitative insulin sensitivity check index is a useful indicator of insulin resistance in Japanese metabolically obese, normal-weight subjects with normal glucose tolerance

To clarify whether quantitative insulin sensitivity check index (QUICKI) is useful as an indicator of insulin resistance in Japanese metabolically obese, normal-weight (MONW, body mass index (BMI) <25 and visceral fat area (VFA) > or = 100 cm2 by abdominal computed tomography scanning) subjects with normal glucose tolerance (NGT). Insulin resistance was measured by QUICKI and euglycemic hyperinsulinemic clamp study (clamp IR) in 27 MONW and 27 normal subjects (BMI <25 and visceral fat area <100 cm2). QUICKI (P<0.01) and clamp IR (p<0.01) were significantly decreased in MONW subjects compared with normal subjects. QUICKI was significantly associated with VFA [MONW subjects: r = -0.459, p<0.02; all (MONW and normal) subjects: r = -0.506, p<0.0001] and with the serum levels of triglycerides (MONW subjects: r = -0.386, p<0.05; all subjects: r = -0.505, p<0.001) in MONW and all subjects. There were significant correlations between clamp IR and VFA (MONW subjects: r = -0.562, p<0.01; all subjects: r = -0.575, p<0.0001), fasting serum levels of insulin (MONW subjects: r = -0.673, p<0.001; all subjects: r = -0.619, p<0.0001) or serum levels of triglycerides (MONW subjects: r = -0.485, p<0.02; all subjects: r = -0.565, p<0.0001) in MONW and all subjects. QUICKI was significantly correlated with clamp IR in MONW (r = 0.754, p<0.0001) and in all subjects (r = 0.568, p<0.0001). QUICKI may be an useful method for assessing insulin resistance in Japanese MONW subjects with NGT.     

Effect of superparamagnetic iron oxide on tumor‐to‐liver contrast at T2*‐weighted gradient‐echo MRI: Comparison between 3.0T and 1.5T MR systems

Purpose

To compare 3.0T and 1.5T MR systems in terms of the effect of superparamagnetic iron oxide (SPIO) on tumor‐to‐liver contrast in T2*‐weighted gradient‐echo MRI.

Materials and Methods

SPIO‐enhanced gradient‐echo MR images of the liver with four different TEs (3, 5.3, 6.5, and 8.5 msec) were obtained by means of 1.5T and 3.0T systems. Quantitative analyses of relative signal intensities (SIs) and relative tumor contrast and qualitative analyses of image quality and lesion conspicuity of the liver were performed in 22 patients, 16 of whom had malignant liver tumors.

Results

With both 1.5T and 3.0T, at TE = 8.4 msec, the relative SI of liver and relative tumor contrast were significantly (P < 0.01) lower and higher, respectively, than that for any of the other TEs. There were no significant differences in the relative SI of the liver, relative tumor contrast, image quality, and tumor conspicuity for the same TE between the 1.5T and 3.0T systems.

Conclusion

Our results showed that the effect of SPIO on tumor‐to‐liver contrast at T2*‐weighted gradient‐echo imaging was similar for the 1.5T and 3.0T systems, and that the 8.4‐msec TE was optimal of the four TEs used in this study at 3.0T. J. Magn. Reson. Imaging 2009;29:595–600. © 2009 Wiley‐Liss, Inc.     

In vivo study on cross talk between inducible nitric-oxide synthase and cyclooxygenase in rat gastric mucosa: effect of cyclooxygenase activity on nitric oxide production

The integrity of gastric mucosa during endotoxemia is maintained by the balance of inflammatory mediators, such as prostanoids originated from cyclooxygenase-2 (COX-2) and nitric oxide (NO) from inducible nitric-oxide synthase (iNOS). Thus, we elucidated in vivo cross talk between prostanoids and NO in gastric mucosa during endotoxemia, using an iNOS-specific inhibitor, N-(3-(aminomethyl)benzyl)acetamidine (1400W); a nonspecific COX inhibitor, indomethacin; and a COX-2-specific inhibitor, N-(2-[cyclohexyloxy]-4-nitrophenyl)methanesulfonamide (NS-398). Gastric mucosal NO and prostaglandin E2 (PGE2), a predominant product of COX, expressed as mean +/- S.D. of five rats per group, were assayed by electron paramagnetic resonance spectrometry and enzyme immunoassay technique, respectively. The levels of NO and PGE2 increased gradually up to 6 h after administration of bacterial lipopolysaccharide (LPS) (NO: control, 0.35 +/- 0.16; 6 h, 13.3 +/- 3.3 nmol/g tissue/30 min; and PGE2: control, 288 +/- 16; 6 h, 806 +/- 15 pg/g tissue). Pretreatment with 1400W decreased the increase in NO level without any effect on the PGE2 level (NO, 4.0 +/- 0.4 nmol/g tissue/30 min; PGE2, 788 +/- 26 pg/g tissue). In contrast, treatment with indomethacin and NS-398 inhibited not only PGE2 level but also NO level in a dose-dependent manner without any significant effect on both iNOS and COX protein and mRNA expression. These results demonstrate that in the LPS-treated rat gastric mucosa, PGE2 enhances the release of NO after activation of iNOS, although NO produced by iNOS does not stimulate the release of PGE2 by COXs. The effect of COX activity on iNOS-NO pathway can be important in the regulation of gastric mucosal integrity in inflammatory states.