Thermoregulatory pathway underlying the pyrogenic effects of prostaglandin E2 in the lateral parabrachial nucleus of male rats.

It has been shown that prostaglandin (PG) E2 synthesized in the lateral parabrachial nucleus (LPBN) is involved in lipopolysaccharide-induced fever. But the neural mechanisms of how intra-LPBN PGE2 induces fever remain unclear. In this study, we investigated whether the LPBN-preoptic area (POA) pathway, the thermoafferent pathway for feed-forward thermoregulatory responses, mediates fever induced by intra-LPBN PGE2 in male rats. The core temperature (Tcore) was monitored using a temperature radiotelemetry transponder implanted in rat abdomen. We showed that microinjection of PGE2 (0.28 nmol) into the LPBN significantly enhanced the density of c-Fos-positive neurons in the median preoptic area (MnPO). The chemical lesioning of MnPO with ibotenate or selective genetic lesioning or inhibition of the LPBN-MnPO pathway significantly attenuated fever induced by intra-LPBN injection of PGE2. We demonstrated that EP3 receptor was a pivotal receptor for PGE2-induced fever, since microinjection of EP3 receptor agonist sulprostone (0.2 nmol) or EP3 receptor antagonist L-798106 (2 nmol) into the LPBN mimicked or weakened the pyrogenic action of LPBN PGE2, respectively, but this was not the case for EP4 and EP1 receptors. Whole-cell recording from acute LPBN slices revealed that the majority of MnPO-projecting neurons originating from the external lateral (el) and dorsal (d) LPBN were excited and inhibited, respectively, by PGE2 perfusion, initiating heat-gain and heat-loss mechanisms. The amplitude but not the frequency of spontaneous and miniature glutamatergic excitatory postsynaptic currents (sEPSCs and mEPSCs) in MnPO-projecting LPBel neurons increased after perfusion with PGE2; whereas the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs) and the A-type potassium (IA) current density did not change. In MnPO-projecting LPBd neurons, neither sEPSCs nor sIPSCs responded to PGE2; however, the IA current density was significantly increased by PGE2 perfusion. These electrophysiological responses and the thermoeffector reactions to intra-LPBN PGE2 injection, including increased brown adipose tissue thermogenesis, shivering, and decreased heat dissipation, were all abolished by L-798106, and mimicked by sulprostone. These results suggest that the pyrogenic effects of intra-LPBN PGE2 are mediated by both the inhibition of the LPBd-POA pathway through the EP3 receptor-mediated activation of IA currents and the activation of the LPBel-POA pathway through the selective enhancement of glutamatergic synaptic transmission via EP3 receptors.

Activation of the endocannabinoid system mediates cardiac hypertrophy induced by rosiglitazone.

Rosiglitazone (RSG) is a synthetic agonist of peroxisome proliferator-activated receptor-γ (PPARγ), which plays a central role in the regulation of metabolism. Meta-analyses have suggested that RSG is associated with increased cardiovascular risk. However, the mechanisms underlying such adverse cardiac effects are still poorly understood. Here, we found that activation of PPARγ by RSG stimulated the endocannabinoid system (ECS), a membrane lipid signaling system, which induced cardiac hypertrophy. In neonatal rat cardiomyocytes, RSG increased the level of anandamide (AEA); upregulated the expression of N-acyl phosphatidylethanolamine phospholipase D (NapePLD), a key enzyme for AEA synthesis; and downregulated the expression of fatty acid amide hydrolase (FAAH), the enzyme responsible for the degradation of AEA. Importantly, PPARγ activation increased the expression of cannabinoid receptor type 1 (CB1) through an identified binding site for PPARγ in the CB1 promoter region. Moreover, both the in vitro and in vivo results showed that inhibition of the ECS by rimonabant, an antagonist of CB1, attenuated RSG-induced cardiac hypertrophy, as indicated by decreased expression of cardiac hypertrophy markers (ANP and BNP), deactivation of the mTOR pathway, and decreased cardiomyocyte size. Thus, these results demonstrated that the ECS functions as a novel target of PPARγ and that the AEA/CB1/mTOR axis mediates RSG-induced cardiac remodeling.

Liver X receptor ß increases aquaporin 2 protein level via a posttranscriptional mechanism in renal collecting ducts.

Liver X receptors (LXRs) including LXRα and LXRß are nuclear receptor transcription factors and play an important role in lipid and glucose metabolism. It has been previously reported that mice lacking LXRß but not LXRα develop a severe urine concentrating defect, likely via a central mechanism. Here we provide evidence that LXRß regulates water homeostasis through increasing aquaporin 2 (AQP2) protein levels in renal collecting ducts. LXRß-/- mice exhibited a reduced response to desmopressin (dDAVP) stimulation, suggesting that the diabetes insipidus phenotype is of both central and nephrogenic origin. AQP2 protein abundance in the renal inner medulla was significantly reduced in LXRß-/- mice but with little change in AQP2 mRNA levels. In vitro studies showed that AQP2 protein levels were elevated upon LXR agonist treatment in both primary cultured mouse inner medullary duct cells (mIMCD) and the mIMCD3 cell line with stably expressed AQP2. In addition, LXR agonists including TO901317 and GW3965 failed to induce AQP2 gene transcription but diminished its protein ubiquitination in primary cultured mIMCD cells, thereby inhibiting its degradation. Moreover, LXR activation-induced AQP2 protein expression was abolished by the protease inhibitor MG132 and the ubiquitination-deficient AQP2 (K270R). Taken together, the present study demonstrates that activation of LXRß increases AQP2 protein levels in the renal collecting ducts via a posttranscriptional mechanism. As such, LXRß represents a key regulator of body water homeostasis.

Prostaglandin E2 receptor EP3 regulates both adipogenesis and lipolysis in mouse white adipose tissue.

Among the four prostaglandin E2 receptors, EP3 receptor is the one most abundantly expressed in white adipose tissue (WAT). The mouse EP3 gene gives rise to three isoforms, namely EP3α, EP3ß, and EP3γ, which differ only at their C-terminal tails. To date, functions of EP3 receptor and its isoforms in WAT remain incompletely characterized. In this study, we found that the expression of all EP3 isoforms were downregulated in WAT of both db/db and high-fat diet-induced obese mice. Genetic ablation of three EP3 receptor isoforms (EP3-/- mice) or EP3α and EP3γ isoforms with EP3ß intact (EP3ß mice) led to an obese phenotype with increased food intake, decreased motor activity, reduced insulin sensitivity, and elevated serum triglycerides. Since the differentiation of preadipocytes and mouse embryonic fibroblasts to adipocytes was markedly facilitated by either pharmacological blockade or genetic deletion/inhibition of EP3 receptor via the cAMP/PKA/PPARγ pathway, increased adipogenesis may contribute to obesity in EP3-/- and EP3ß mice. Moreover, both EP3-/- and EP3ß mice had increased lipolysis in WAT mainly due to the activated cAMP/PKA/hormone-sensitive lipase pathway. Taken together, our findings suggest that EP3 receptor and its α and γ isoforms are involved in both adipogenesis and lipolysis and influence food intake, serum lipid levels, and insulin sensitivity.

Metformin Restores Intermediate-Conductance Calcium-Activated K⁺ Channel- and Small-Conductance Calcium-Activated K⁺ Channel-Mediated Vasodilatation Impaired by Advanced Glycation End Products in Rat Mesenteric Artery. [Corrected].

The present study was designed to investigate the effect of metformin on the impairment of intermediate-conductance and small-conductance Ca(2+)-activated potassium channels (IKCa and SKCa)-mediated relaxation in diabetes and the underlying mechanism. The endothelial vasodilatation function of mesenteric arteries was assessed with the use of wire myography. Expression levels of IKCa and SKCa and phosphorylated Thr(172) of AMP-activated protein kinase (AMPK) were measured using Western blot technology. The channel activity was observed using a whole-cell patch voltage clamp. Reactive oxygen species (ROS) were measured using dihydroethidium and 2',7'-dichlorofluorescein diacetate. Metformin restored the impairment of IKCa- and SKCa-mediated vasodilatation in mesenteric arteries from streptozotocin-induced type 2 diabetic rats and that from normal rats incubated with advanced glycation end products (AGEs) for 3 hours. In cultured human umbilical vein endothelial cells (HUVECs), 1 µM metformin reversed AGE-induced increase of ROS and attenuated AGE- and H2O2- induced downregulation of IKCa and SKCa after long-term incubation (>24 hours). Short-term treatment (3 hours) with 1 µM metformin reversed the decrease of IKCa and SKCa currents induced by AGE incubation for 3 hours without changing the channel expression or the AMPK activation in HUVECs. These results are the first to demonstrate that metformin restored IKCa- and SKCa-mediated vasodilatation impaired by AGEs in rat mesenteric artery, in which the upregulation of channel activity and protein expression is likely involved.

Advanced glycation end products impair K(Ca)3.1- and K(Ca)2.3-mediated vasodilatation via oxidative stress in rat mesenteric arteries.

The present study was designed to investigate the role of advanced glycation end products (AGEs) in intermediate-conductance and small-conductance Ca(2+)-activated potassium channels (KCa3.1 and KCa2.3)-mediated relaxation in rat resistance arteries and the underlying mechanism. The endothelial function of mesenteric arteries was assessed with the use of wire myography. Expression levels of KCa3.1 and KCa2.3 were measured by using Western blot. Reactive oxygen species (ROS) were measured by using dihydroethidium and 2', 7'-dichlorofluorescein diacetate. KCa3.1 and KCa2.3-mediated vasodilatation responses to acetylcholine and NS309 (opener of KCa3.1 and KCa2.3) were impaired by incubation of the third-order mesenteric arteries from normal rats with AGEs (200 µg ml(-1) for 3 h). In cultured human umbilical vein endothelial cells (HUVECs), AGEs increased ROS level and decreased the protein expression of KCa3.1 and KCa2.3. Antioxidant alpha lipoic acid restored the impairment in both vasodilatation function and expression of KCa3.1 and KCa2.3. H2O2 could mimic the effect of AGEs on the protein expression of KCa3.1 and KCa2.3 in cultured HUVECs. These results demonstrate for the first time that AGEs impaired KCa3.1 and KCa2.3-mediated vasodilatation in rat mesenteric arteries via downregulation of both KCa3.1 and KCa2.3, in which the enhanced oxidative stress was involved.

Aqua-(pyridine-3-carb-oxy-lic acid-κN)(pyridine-2,6-dicarboxyl-ato-κO,N,O)copper(II) monohydrate.

In the title Cu(II) complex, [Cu(C(7)H(3)NO(4))(C(6)H(5)NO(2))(H(2)O)]·H(2)O, the environment of the Cu(2+) ion is a distorted square pyramid with the axial site occupied by the O atom from the coordinated water mol-ecule and the square base formed by two O and two N atoms from the tridentate anion and the neutral monodentate pyridine-3-carboxylic acid ligand. O-H⋯O hydrogen bonds, as well as π-π inter-actions [centroid-centroid distance = 3.945 (3) Å] contribute to the stabilization of this structure.

[The interaction of beta-cyclodextrin with etoposide studied by fluorescence spectroscopy].

The fluorescence spectroscopy and UV spectroscopy have been used to monitor the inclusion phenomena of VP-16 with beta-cyclodextrin (beta-CD), together with studies concerning the effects of reaction time, temperature and concentration on this behavior. The results show that the fluorescence intensity increased when VP-16 and beta-CD forming a 1 : 1 inclusion complex, which indicate that beta-CD has fluorescence sensitizing effect on the VP-16. At 22 degrees C, the inclusion constant was 2.63 x 10(5) L x mol(-1) at pH 7.0. VP-16 has maximum emission wavelength at 316 nm under the optimum conditions. According to this, the quantitative micro-detection method of VP-16 by fluorescence spectrometry was established. The linear regression equation was y = 1.107 89 x 10(70 x + 95.898 1, with a correlation coefficient of 0.999 9. The detection limit was 2.094 x 10(-7) mol x L(-1).

The estimation of the number of underground coal miners and the annual dose to coal miners in China.

This paper introduces an estimation method for the number of underground coal miners and the annual dose to coal miners in China. It shows that there are about 6 million underground miners at present and the proportion is about 1, 1 and 4 million for national key coal mines, state-owned local coal mines, and township and private-ownership coal mines, respectively. The collective dose is about 1.65 x 10(4) person-Sv y(-1), of which township and private-ownership coal mines contribute about 91%. This paper also points out that the 2000 UNSCEAR report gives the number of miners of coal production and their collective dose, which are underestimated greatly because the report only includes the number of underground miners in national key coal mines, which only accounts for 1/6 of the workers all working under the best ventilation conditions in China.

[Roles of shear stress in atherogenesis].

Located between circulating blood and vessel wall, vascular endothelial cells (ECs) are constantly exposed to shear stress resulting from blood flow. The mechanical actions of shear stress can be detected by mechanosensors on ECs and converted into specific signaling pathways to mediate the structural and functional remodeling. Patterns of shear stress may contribute to the focal distribution of atherosclerotic lesions. Here, we review recent advances regarding the roles of shear stress in atherogenesis.

The utility of intraoperative evaluation of sentinel lymph nodes in breast cancer.

BACKGROUND: In breast cancer treatment, intraoperative sentinel lymph node (SLN) evaluation is used to identify patients who may potentially benefit from immediate completion of axillary lymph node dissection. METHODS: Prospectively collected breast cancer registry data identified 516 SLN biopsies between January 2003 and December 2005. Intraoperative evaluation (IE) of the SLNs was performed in 479 axillae. Final pathology by hematoxylin and eosin and, for negative nodes, by immunohistochemical stains was compared with the IE result. The effect of IE and final pathology on surgical treatment was examined. RESULTS: The sensitivities for IE of N0(i+) (n = 39), N1mi (n = 41), and N1a-3a (n = 89) metastases were 0%, 5%, and 63%, respectively. The specificity was 99.7%. IE identified 57 (44%) of SLN-positive (N1mi and N1a-3a) axillae, thus resulting in synchronous axillary lymph node dissection for those patients. Reoperation for false-negative IEs (N1mi or N1a-3a with negative IE) occurred in only 27 axillae (39%). CONCLUSIONS: IE of SLNs has adequate sensitivity and excellent specificity. In addition to allowing patients to benefit from synchronous surgery, IE helped patients to receive care in concordance with recommended practice guidelines. The false-negative IE of SLNs highlights uncertainty with the clinical significance of axillary nodal staging when only small amounts of metastatic disease are identified in the axilla.

Rosiglitazone inhibits angiotensin II-induced CTGF expression in vascular smooth muscle cells - role of PPAR-gamma in vascular fibrosis.

Angiotensin (Ang) II plays a pivotal role in vascular fibrosis, which leads to serious complications in hypertension and diabetes. Connective tissue growth factor (CTGF) is a potent profibrotic factor implicated in the Ang II-induced pathologic fibrosis process. PPAR-gamma activators thiazolidinediones have been recently reported to have beneficial vascular effects. However, their effects and related molecular mechanisms on extracellular matrix (ECM) turnover in vascular smooth muscle cells (VSMCs) are unknown. The present study evaluated the regulation of Ang II-induced CTGF, ECM production and cell growth by rosiglitazone in VSMCs. In aorta of Ang II-infused rats, CTGF expression was markedly increased, and type III collagen and fibronectin overexpression was observed. Cotreatment with rosiglitazone diminished these changes, whereas increased nuclear PPAR-gamma expression in VSMCs. In growth-arrested VSMCs, rosiglitazone attenuated the proliferation and apoptosis, increased PPAR-gamma production and activation, and reduced CTGF and ECM production in response to Ang II in a dose-dependent fashion. These inhibitory effects were attenuated by the pretreatment of cells with PPAR-gamma antagonist GW9662 or bisphenol A diglycidyl ether (BADGE). Furthermore, rosiglitazone inhibited Ang II-induced Smad2 production and phosphorylation but had no effect on transforming growth factor-beta(1) (TGF-beta(1)) expression. These results suggest that in Ang II-stimulated VSMCs, rosiglitazone caused an antiproliferative, antiapototic effect and reduces ECM production through mechanisms that include reducing CTGF expression, and a crosstalk between PPAR-gamma and Smad may be involved in the inhibitory effects of rosiglitazone. This novel finding suggests a role of PPAR-gamma activators in preventing Ang II-induced vascular fibrosis.

Accuracy of intraoperative imprint cytology of sentinel lymph nodes in breast cancer.

BACKGROUND: In breast cancer treatment, immediate completion of axillary lymph node dissection (ALND) can be performed if the intraoperative sentinel lymph node (SLN) examination is positive. This study evaluates the accuracy of intraoperative imprint cytology (IC) for detecting SLN metastases. METHODS: Pathology reports from 385 SLN biopsy examinations were reviewed retrospectively. The SLNs were serially sectioned perpendicular to the long axis and IC was performed intraoperatively. The SLNs then were formalin-fixed for permanent sections. Final pathology was compared with the intraoperative IC results. RESULTS: The sensitivities for IC detection of N0(i+) (n = 36), N1mi (n = 24), and N1a-3a (n = 65) metastases were 0%, 4%, and 74%, respectively. The specificity was 100%. CONCLUSIONS: Final pathology identified 89 (23%) patients with N1 or greater disease. IC allowed 49 (55%) of these patients to undergo synchronous completion of ALND. No unnecessary completion ALNDs were performed. The sensitivity of IC decreased with decreasing size of the metastasis.

[Expression of peroxisome proliferator-activated receptors Y changes with age in vascular smooth muscle cells of spontaneously hypertensive rat].

OBJECTIVE: In order to elucidate the relationship between PPAR-gamma and the development of hypertension, we detected the expression of peroxisome proliferator-activated receptors gamma (PPAR-gamma) in the vascular smooth muscle cells (VSMCs) and the VSMC proliferation of spontaneously hypertensive rats (SHR) at different ages. METHODS: The expression of PPAR-gamma in the intact vascular tissues of rats at different ages were detected by immunohistochemistry. Aortic VSMCs were cultured. PPAR-gamma mRNA in primary and low-passage cultured VSMCs of various ages were determined by RT-PCR, and proteins were evaluated by immunohistochemistry and age matched Western Blot. Age matched Wistar-Kyoto rats (WKY) were used as control. RESULTS: This experiment demonstrated that the expression of PPAR-gamma increased with age in the intact aorta tissues of SHR. The expression of PPAR-gamma did not continuously increase in 24w-old SHR when compared with that in 16w-old SHR. No difference between 4w-, 24w-old SHR and age matched WKY was observed, but the expression of PPAR-gamma was greater in 8w- and 16w old SHR than in age matched WKY. In primary and low-passage cultured VSMCs, the expression of PPAR-gamma mRNA and protein increased with age both in SHR VSMCs and WKY VSMCs of 4w, 8w and 16w old, and no difference between 4w- and 24w-old SHR and WKY was noted, but the expression of PPAR-gamma was higher in 8w- and 16w-old SHR than in age matched WKY. PPAR-gamma expression in 24w-old SHR did not increase and it was equal to 16w-old SHR and 24w-old WKY. CONCLUSION: These datas on SHR suggest that the expression of PPAR-gamma changes with age and the development of high blood pressure. PPAR-gamma expression may play a compensatory role in hypertension, but this compensatory action is limited.

[Effect of endothelin-1 stimulation on peroxisome proliferator-activated receptor-gamma expression in vascular smooth muscle cells].

OBJECTIVE: To investigate the effect of endothelin-1 (ET-1) on the expression of peroxisome proliferators-activated receptor-gamma in vascular smooth muscle cells. METHODS: The first to the third passages of aortic vascular smooth muscle cells (VSMCs) isolated from 16-week-old Wistar rats were cultured in vitro and stimulated by ET-1 for 12, 24, 48, and 72 h, respectively, and at different concentrations of ET-1 for 48 h. PPAR-gamma mRNA expression of the cells was detected by reverse transcription (RT)-PCR and PPAR-gamma protein by Western blotting after the stimulations, and the proliferation of VSMCs was evaluated by MTT assay. RESULTS: No changes in PPAR-gamma mRNA and protein expressions were observed in the VSMCs after ET-1 stimulation for 12 h (P>0.05), and when the stimulation was prolonged to 24 h, slight decrease in the expressions occurred but the difference was not statistically significant in comparison with the control group (P<0.05). After 48 to 72 hour's ET-1 stimulation, the expressions of both PPAR-gamma mRNA and protein were markedly decreased as compares with the control group (P<0.01). The expressions of PPAR-gamma in mRNA and protein were both decreased with the increase of ET-1 concentration after stimulation for 48 h. VSMC proliferation occurred at 12 h during ET-1 stimulation and increased with time and ET-1 concentration. CONCLUSION: ET-1 stimulation can induce VSMC proliferation and decrease the expressions of both PPAR-gamma mRNA and protein.

[Increased expression of peroxisome proliferator-activated receptor-gamma in endothelial cells of spontaneously hypertensive rats].

OBJECTIVE: To evaluate the relationship between hypertension and the expression level of PPAR-gamma in endothelial cells (ECs) of spontaneously hypertensive rats (SHR). METHODS: PPAR-gamma protein expression in ECs of 4-week and 16-week SHR was detected by immunohistochemistral technique and analyzed by image acquiring and analysis system, and age matched Wistar-Kyoto rats (WKY) were used as controls. The aortic ECs of different-aged rats were primarily cultured, and the protein and mRNA level of PPAR-gamma in cultured ECs (< or =3 passages) were detected by Western blotting and reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The blood pressure of 4-week SHR was slightly higher than those of 4-week WKY (P < 0.05). The protein and mRNA levels of PPAR-gamma in 4-week SHR were also higher than that of 4-week WKY, but the differences had no statistical significance (P > 0.05). Compared with the 16-week WKY, the blood pressure of 16-week SHR greatly increased (P < 0.01), and the protein and mRNA levels of PPAR-gamma in ECs from 16w SHR were approximately 1.5 times higher than those of the age matched WKY (P < 0.01). The protein and mRNA levels of PPAR-gamma in ECs from 16-week SHR were 2.5 times higher than those of 4-week SHR (P < 0.01), while in 16-week WKY it was only 1.5 times higher than those of 4-week WKY (P < 0.01). Conclusion In accordance with the hypertension progress, the protein and mRNA levels of PPAR-gamma in SHR can significantly increase.