The pancreatic clock is a key determinant of pancreatic fibrosis progression and exocrine dysfunction

Chronic pancreatitis (CP) is characterized by progressive fibrosis and exocrine dysregulation, which have long been considered irreversible. As a peripheral oscillator, the pancreas harbors autonomous and self-sustained timekeeping systems in both its endocrine and exocrine compartments, although the role of the latter remains poorly understood. By using different models of CP established in mice with dysfunctional pancreatic clocks, we found that the local clock played an important role in CP pathology, and genetic or external disruption of the pancreatic clock exacerbated fibrogenesis and exocrine insufficiency. Mechanistically, an impaired retinoic acid receptor-related orphan receptor A (Rora)/nuclear receptor subfamily 1, group D, member 1 (Nr1d1)/aryl hydrocarbon receptor nuclear translocator-like (Arntl or Bmal1) loop, called the circadian stabilizing loop, resulted in the deficiency of pancreatic Bmal1, which was responsible for controlling the fibrogenic properties of pancreatic stellate cells (PSCs) and for rewiring the function of acinar cells in a clock-TGF signaling-IL-11/IL-11RA axis-dependent manner. During PSC activation, the antagonistic interaction between Nr1d1 and Rora was unbalanced in response to the loss of cytoplasmic retinoid-containing lipid droplets. Patients with CP also exhibited reduced production of endogenous melatonin. Enhancing the clock through pharmacological restoration of the circadian stabilizing loop using a combination of melatonin and the Rora agonist SR1078 attenuated intrapancreatic pathological changes in mouse models of CP. Collectively, this study identified a protective role of the pancreatic clock against pancreatic fibrosis and exocrine dysfunction. Pancreatic clock-targeted therapy may represent a potential strategy to treat CP.

Abstract 2057: Utilizing ‘viral mimicry’ as a novel therapeutic approach in conjunction with anti-PD-1 immunotherapy increases immune activation and extends survival in a glioblastoma murine model

Therapeutic advances of glioblastoma (GBM) in the last two decades have only extended survival by a few months, maintaining a five-year survival rate of less than five percent. While immunotherapy has shown promise for other types of cancer, it has proved less efficacious as a monotherapy in GBM, partly due to a suppressive immune microenvironment. Being able to stimulate anti-tumor immune activity through alternative methods may allow for a more successful immunotherapeutic response. One such method is by disengaging epigenetic maintenance of repetitive element (RE) silencing. It was recently shown that the epigenetic pathway, FBXO44/SUV39H1, could be targeted specifically in cancer cells to release inhibition of REs such as endogenous retroviruses and retrotransposons. This effect resulted in increased activation of antiviral pathways and interferon signaling. We hypothesized using this treatment in conjunction with anti-PD-1 immunotherapy would allow for a synergistic effect against GBM tumor growth and increased survival. We therefore treated mice with intracranially implanted GL261 cells with a combined therapy of anti-PD-1 and SUV39H1 inhibition. One week after treatment started, we used single cell analysis using multiplexed flow cytometry to look at different immune populations. The largest percentage of immune cells comprised macrophages; with multiplex flow analysis, we were able to differentiate activated microglia (the brain resident immune cell) versus bone marrow derived macrophages (BMDMs; macrophages derived from the blood) based on CD49d expression. While no differences were found in overall macrophage numbers, the percentage of microglia was significantly higher than BMDMs. Strikingly, expression of PD-1 was significantly higher on microglia compared to BMDMs, while CD206, a marker of immune suppression, was significantly higher on the latter. T cells were also examined, with overall numbers again, not significantly different between treatment groups. However, those from mice treated with either the SUV39H1 inhibitor alone or in combination with anti-PD-1 had significantly higher levels of the co-stimulatory molecule CD40L on both CD4+ and CD8+ T cells. Lastly, survival analysis revealed a significant increase in survival with combinatorial treatment compared to either therapy alone or no treatment control. These results indicate the efficacy of an alternative treatment method working synergistically with anti-PD-1 immunotherapy to stimulate the immune system and slow GBM progression in a murine model.

Citation Format: Katie B. Grausam, Jia Z. Shen, Joshua J. Breunig, Charles Spruck, Stephen L. Shiao. Utilizing ‘viral mimicry’ as a novel therapeutic approach in conjunction with anti-PD-1 immunotherapy increases immune activation and extends survival in a glioblastoma murine model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2057.

PDGF signaling inhibits mitophagy in glioblastoma stem cells through N6-methyladenosine

Dysregulated growth factor receptor pathways, RNA modifications, and metabolism each promote tumor heterogeneity. Here, we demonstrate that platelet-derived growth factor (PDGF) signaling induces N⁶-methyladenosine (m⁶A) accumulation in glioblastoma (GBM) stem cells (GSCs) to regulate mitophagy. PDGF ligands stimulate early growth response 1 (EGR1) transcription to induce methyltransferase-like 3 (METTL3) to promote GSC proliferation and self-renewal. Targeting the PDGF-METTL3 axis inhibits mitophagy by regulating m⁶A modification of optineurin (OPTN). Forced OPTN expression phenocopies PDGF inhibition, and OPTN levels portend longer survival of GBM patients; these results suggest a tumor-suppressive role for OPTN. Pharmacologic targeting of METTL3 augments anti-tumor efficacy of PDGF receptor (PDGFR) and mitophagy inhibitors in vitro and in vivo. Collectively, we define PDGF signaling as an upstream regulator of oncogenic m⁶A regulation, driving tumor metabolism to promote cancer stem cell maintenance, highlighting PDGF-METTL3-OPTN signaling as a GBM therapeutic target.

A FBXO7/EYA2-SCFFBXW7 axis promotes AXL-mediated maintenance of mesenchymal and immune evasion phenotypes of cancer cells

A mesenchymal tumor phenotype associates with immunotherapy resistance, although the mechanism is unclear. Here, we identified FBXO7 as a maintenance regulator of mesenchymal and immune evasion phenotypes of cancer cells. FBXO7 bound and stabilized SIX1 co-transcriptional regulator EYA2, stimulating mesenchymal gene expression and suppressing IFNα/β, chemokines CXCL9/10, and antigen presentation machinery, driven by AXL extracellular ligand GAS6. Ubiquitin ligase SCF^FBXW7 antagonized this pathway by promoting EYA2 degradation. Targeting EYA2 Tyr phosphatase activity decreased mesenchymal phenotypes and enhanced cancer cell immunogenicity, resulting in attenuated tumor growth and metastasis, increased infiltration of cytotoxic T and NK cells, and enhanced anti-PD-1 therapy response in mouse tumor models. FBXO7 expression correlated with mesenchymal and immune-suppressive signatures in patients with cancer. An FBXO7-immune gene signature predicted immunotherapy responses. Collectively, the FBXO7/EYA2-SCF^FBXW7 axis maintains mesenchymal and immune evasion phenotypes of cancer cells, providing rationale to evaluate FBXO7/EYA2 inhibitors in combination with immune-based therapies to enhance onco-immunotherapy responses.

Transcription Elongation Machinery Is a Druggable Dependency and Potentiates Immunotherapy in Glioblastoma Stem Cells

Glioblastoma (GBM) is the most lethal primary brain cancer characterized by therapeutic resistance, which is promoted by GBM stem cells (GSC). Here, we interrogated gene expression and whole-genome CRISPR/Cas9 screening in a large panel of patient-derived GSCs, differentiated GBM cells (DGC), and neural stem cells (NSC) to identify master regulators of GSC stemness, revealing an essential transcription state with increased RNA polymerase II-mediated transcription. The YY1 and transcriptional CDK9 complex was essential for GSC survival and maintenance in vitro and in vivo. YY1 interacted with CDK9 to regulate transcription elongation in GSCs. Genetic or pharmacologic targeting of the YY1-CDK9 complex elicited RNA m⁶A modification-dependent interferon responses, reduced regulatory T-cell infiltration, and augmented efficacy of immune checkpoint therapy in GBM. Collectively, these results suggest that YY1-CDK9 transcription elongation complex defines a targetable cell state with active transcription, suppressed interferon responses, and immunotherapy resistance in GBM. SIGNIFICANCE: Effective strategies to rewire immunosuppressive microenvironment and enhance immunotherapy response are still lacking in GBM. YY1-driven transcriptional elongation machinery represents a druggable target to activate interferon response and enhance anti-PD-1 response through regulating the m⁶A modification program, linking epigenetic regulation to immunomodulatory function in GBM.This article is highlighted in the In This Issue feature, p. 275.

Targeting EYA2 tyrosine phosphatase activity in glioblastoma stem cells induces mitotic catastrophe

Glioblastoma ranks among the most lethal of primary brain malignancies, with glioblastoma stem cells (GSCs) at the apex of tumor cellular hierarchies. Here, to discover novel therapeutic GSC targets, we interrogated gene expression profiles from GSCs, differentiated glioblastoma cells (DGCs), and neural stem cells (NSCs), revealing EYA2 as preferentially expressed by GSCs. Targeting EYA2 impaired GSC maintenance and induced cell cycle arrest, apoptosis, and loss of self-renewal. EYA2 displayed novel localization to centrosomes in GSCs, and EYA2 tyrosine (Tyr) phosphatase activity was essential for proper mitotic spindle assembly and survival of GSCs. Inhibition of the EYA2 Tyr phosphatase activity, via genetic or pharmacological means, mimicked EYA2 loss in GSCs in vitro and extended the survival of tumor-bearing mice. Supporting the clinical relevance of these findings, EYA2 portends poor patient prognosis in glioblastoma. Collectively, our data indicate that EYA2 phosphatase function plays selective critical roles in the growth and survival of GSCs, potentially offering a high therapeutic index for EYA2 inhibitors.

Targeting FBXO44/SUV39H1 elicits tumor cell-specific DNA replication stress and viral mimicry

Repetitive elements (REs) are normally transcriptionally silenced in somatic cells by repressive epigenetic modifications, which are thought to include DNA methylation and histone modifications such as deacetylation, H3K9me3, and H4K20me3. Although, it is unclear how RE silencing is maintained through DNA replication cycles in rapidly growing cancer cells. On the other hand, the reactivation of endogenous retroelements beyond a threshold level of tolerance in cancer cells, such as by treatment with DNA demethylating agents or HDAC or LSD1 inhibitors, can induce viral mimicry responses that augment certain cancer therapies, including immunotherapy. However, these agents can also affect normal cells presenting obvious side effects. Therefore, uncovering cancer cell-specific RE silencing mechanisms could provide a basis for the development of a new generation of cancer immunotherapy drugs. In our study (Shen et al. (2020), Cell, doi: 10.1016/j.cell.2020.11.042), through a high-content RNAi screen we identified FBXO44 as a key regulator of H3K9me3-mediated transcriptional silencing of REs in cancer cells. Inhibition of FBXO44 or its co-factor SUV39H1 stimulated antiviral pathways and interferon (IFN) signaling and induced replication stress and DNA double-strand breaks (DSBs) in cancer cells, leading to restricted tumor growth and synergy with anti-PD-1 therapy (Figure 1). Figure 1

[Clinical significance of hypermethylation of DLC-1 gene in myelodysplastic syndrome patients and effects of decitabine on DLC-1 gene expression]

Objective: To detect the methylation status of DLC-1 gene in the patients with myelodysplastic syndrome(MDS), the effect of abnormal methylation of DLC-1 gene on the expression of DLC-1 gene, the clinical significance of methylation of DLC-1 gene in MDS patients, and the effect of decitabine on DLC-1 gene expression. Methods: A total of 43 MDS patients were treated in Fujian Medical University Union Hospital from 2013 to 2015. Methylation status of DLC-1 gene in MDS patients were detected by the methylation specific PCR(MSP). The expression of DLC-1 gene mRNA was determined with real-time fluorescence quantitative PCR(RTFQ-PCR). MDS patients were divided into 5 groups (very low-risk, low-risk, intermediate-risk, high-risk and very high-risk, n=0, 8, 7, 18, 10) according to WPSS classification. And the clinical significance of methylation of DLC-1 gene in patients with MDS were investigated. In order to investigate the change in gene methylation and expression of DLC-1 gene after treatment with decitabine, methylation statuses of DLC-1 gene in MDS patients before and after be treated with decitabine were detected by the bisulfite sequencing PCR(BSP). The expressions of DLC-1 gene mRNA of these patients were determined with RTFQ-PCR. Results: Hypermethylation of CpG island of DLC-1 gene was observed in 55.16%(22/43)MDS patients. The expressions of DLC-1 gene mRNA in methylation positive patients were significantly lower than that in methylation negative patients (0.32±0.06 vs 0.91±0.11)(P=0.008). For MDS patients, the DLC-1 methylation rate of intermediate-and high-risk patient was 21/35, which was significantly higher than that of low-risk patient(1/8, P=0.006). The methylation status of DLC-1 gene were monitored in 8 patients before and after treatment with the decitabine (decitabine 20 mg/m(2,) d1-d5/d28, more than 4 courses) , the methylation rate of DLC-1 gene dropped from 57.50%±5.11% to 14.13%±2.07% after treatment(P=0.010). The expression of DLC-1 gene increased after treatment with decitabine(0.67±0.08 vs 0.28±0.06, P=0.015). Conclusions: Methylation of DLC-1 gene is common in MDS patients and may be associated with poor prognosis. Decitabine may activate the expression of DLC-1 gene by demethylation, which may be one of the mechanisms for the treatment of patients with MDS.

[The 459th case: arthralgia, fever, rash, and thrombocytopenia]

The differential diagnoses of reactive arthritis presenting as arthralgia should be considered as diverse disorders, especially when the symptoms cannot be fully explained by some definite diseases. Do not ignore the indication of bone marrow aspiration. We reported a 50-year-old woman who complained of arthralgia, recurrent fever and rash 9 months ago. Laboratory exams showed mild leukopenia, anemia, thrombocytopenia and increased lymphocyte proportion. She was treated with glucocorticoid after the diagnosis of connective tissue disease was suspected. Until platelet count abruptly decreased to very low level, the final diagnosis of acute lymphoblastic leukemia was made through bone marrow morphology, flow cytometry, and chromosome examination. Therefore, a small number of leukemia is not easily diagnosed by routine operations. Thus when diagnoses are not determined with recurrent symptoms, cautious observation and further examination are required to avoid misdiagnoses or missed diagnoses of acute leukemia.

CsSAD: a fatty acid desaturase gene involved in abiotic resistance in Camellia sinensis (L.)

Tea (Camellia sinensis L.) is a thermophilic evergreen woody plant that has poor cold tolerance. The SAD gene plays a key role in regulating fatty acid synthesis and membrane lipid fluidity in response to temperature change. In this study, full-length SAD cDNA was cloned from tea leaves using rapid amplification of cDNA ends and polymerase chain reaction (PCR)-based methods. Sequence analysis demonstrated that CsSAD had a high similarity to other corresponding cDNAs. At 25°C, the CsSAD transcriptional level was highest in the leaf and lowest in the stem, but there was no obvious difference between the root and stem organs. CsSAD expression was investigated by reverse transcription-PCR, which showed that CsSAD was upregulated at 4° and -5°C. At 25°C, CsSAD was induced by polyethylene glycol, abscisic acid, and wounding, and a similar trend was observed at 4°C, but the mean expression level at 4°C was lower than that at 25°C. Under natural cold acclimation, the 'CsCr05' variety's CsSAD expression level increased before decreasing. The CsSAD expression level in variety 'CsCr06' showed no obvious change at first, but rapidly increased to a maximum when the temperature was very low. Our study demonstrates that CsSAD is upregulated in response to different abiotic conditions, and that it is important to study the stress resistance of the tea plant, particularly in response to low temperature, drought, and wounding.

CCL2-dependent macrophage recruitment is critical for mineralocorticoid receptor-mediated cardiac fibrosis, inflammation, and blood pressure responses in male mice

Recent studies show that mice with selective deletion of the mineralocorticoid receptor (MR) in macrophages are protected from mineralocorticoid-induced cardiac fibrosis and hypertension without altering cardiac macrophage accumulation. However, it is unclear whether preventing macrophages from entering cardiac tissue would provide similar or additional protection in this disease setting. Therefore, we examined mineralocorticoid-induced cardiovascular disease in mice lacking the CCL2 gene (encoding monocyte chemoattractant protein-1), which have a markedly reduced capacity to recruit proinflammatory tissue macrophages. Male wild-type (WT) and CCL2-null mice were treated for 8 days or 8 weeks with either vehicle (control, CON) or deoxycorticosterone (DOC). At both time points, there was a significant reduction in DOC-induced macrophage recruitment (50% at 8 d and 75% at 8 wk) in the heart with a corresponding suppression of cardiac inflammatory markers in the CCL2-null mice. CCL2-null mice given DOC/salt also displayed 35% less cardiac fibrosis at 8 weeks vs WT DOC. Absence of recruited macrophages in CCL2-null mice promotes greater collagen breakdown by matrix metalloproteinase-9 in the heart and also leads to significantly reduced cardiac fibroblast and myofibroblast numbers. Systolic blood pressure (BP) after DOC/salt was significantly lower in CCL2-null than for WT mice. In the aorta at 8 weeks, MR-responsive gene expression remained intact. However, macrophage-mediated proinflammatory gene expression was reduced in the CCL2-null mice and may account for differential regulation of BP. Our data thus demonstrate an important role for CCL2-dependent macrophage recruitment in MR-dependent cardiac inflammation and remodeling and in the regulation of systolic BP.

Pentamethylquercetin generates beneficial effects in monosodium glutamate-induced obese mice and C2C12 myotubes by activating AMP-activated protein kinase

AIMS/HYPOTHESIS

Pentamethylquercetin (PMQ) has recently been shown to have glucose-lowering properties. Here, we aimed to characterise the effectiveness and underlying mechanisms of PMQ for ameliorating metabolic disorders in vivo and vitro.

METHODS

We generated a mouse model of obesity by neonatal administration of monosodium glutamate (MSG) and used it to assess the properties of PMQ as a treatment for metabolic disorders. We also investigated the possible underlying mechanisms of PMQ in the prevention of metabolic disorders.

RESULTS

Compared with normal mice, MSG mice had metabolic disorders, including central obesity, hyperinsulinaemia, insulin resistance, hyperglycaemia, hyperlipidaemia, decreased phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), and downregulated levels of GLUT4 in gastrocnemius muscles. In MSG mice, PMQ treatment (5, 10, 20 mg/kg daily) reduced body weight gain, waist circumference, adipose tissue mass, serum glucose, triacylglycerol and total cholesterol, while improving insulin resistance, activating AMPK and increasing ACC phosphorylation and GLUT4 abundance. In C2C12 myotubes, PMQ (10 μmol/l) increased glucose consumption by ∼65%. PMQ treatment (1-10 μmol/l) also activated AMPK, increased ACC phosphorylation and GLUT4 abundance, and upregulated the expression of some key genes involved in fatty acid oxidation.

CONCLUSIONS/INTERPRETATION

These findings suggest that PMQ can ameliorate metabolic disorders at least in part via stimulation of AMPK activity.

Pharmacokinetics and bioavailability of cefquinome in healthy piglets

A study on bioavailability and pharmacokinetics of cefquinome in piglets was conducted after intravenous (i.v.) and intramuscular (i.m.) administrations of 2.0 mg/kg of body weight, respectively. Plasma concentrations were measured by high-performance liquid chromatography assay with UV detector at 268-nm wavelength. Plasma concentration-time data after i.v. administration were best fit by a two-compartment model. The pharmacokinetic values were distribution half-life 0.27 +/- 0.21 h, elimination half-life 1.85 +/- 1.11 h, total body clearance 0.26 +/- 0.08 L/kg.h, area under curve 8.07 +/- 1.91 microg x h/mL and volume of distribution at steady state 0.46 +/- 0.10 L/kg. Plasma concentration-time data after i.m. administration were also best fit by a two-compartment model. The pharmacokinetic parameters were distribution half-life 0.88 +/- 0.42 h, elimination half-life 4.36 +/- 2.35 h, peak concentration 4.01 +/- 0.57 microg/mL and bioavailability 95.13 +/- 9.93%.

Preparation and evaluation of a microemulsion for oral delivery of berberine

The principal aim of this study was to develop an oral microemulsion formulation of berberine in order to improve its bioavailability. The Microemulsion was prepared with pharmaceutically acceptable ingredients such as oleic acid, Tween 80 and PEG400. Phase diagrams were drawn to elucidate the phase behavior of systems, which were composed of Tween 80 as surfactant and PEG400 as cosurfactant. A single isotropic region, considered to be a bicontinuous microemulsion, was detected in the pseudo ternary phase diagrams. The berberine-loaded microemulsion was characterized by viscosity, refractive index, electrical conductivity and particle size. In vivo pharmacokinetic profile and oral bioavailability were also investigated in rats. The optimized formulation was as follows: 15 wt.% oleic acid, 17 wt.% Tween-80, 17 wt.% PEG400, and 51 wt.% water. The formulated microemulsion was found to be relatively uniform in size (24.0 nm). The in vivo study indicated that the bioavailability of the oral berberine-loaded microemulsion formulation was 6.47 times greater than that of the berberine tablet suspensions. The results suggest that the microemulsion is a promising oral drug delivery system for berberine.

Efficacy of decoquinate against drug sensitive laboratory strains of Eimeria tenella and field isolates of Eimeria spp. in broiler chickens in China

The efficacy of decoquinate against Eimeria infections in broiler chickens was evaluated using two drug sensitive laboratory strains of Eimeria tenella and 20 field isolates of Eimeria spp. collected from farms in China where various anticoccidials (including maduramicin) had been used. Decoquinate (20-40 ppm in feed) and maduramicin (5 ppm) were efficacious against E. tenella laboratory strains, but decoquinate more so than maduramicin. Body weight gains of E. tenella infected chickens were significantly improved, and caecal lesions were prevented, by feeding either decoquinate or maduramicin. Decoquinate also prevented oocyst production, but maduramicin did not. Most (18/20) Eimeria field isolates were resistant to maduramicin, judged by oocyst production; decoquinate at > or =20 ppm completely controlled all 20 field isolates. Decoquinate has potential value as a broiler anticoccidial in China and other countries where it has not been previously used.

Technical Note: A monoclonal antibody-based immunoassay for determination of ractopamine in swine feeds1

An ELISA was developed for routine screening of ractopamine in swine feeds. Swine feed samples were extracted and purified, and the aqueous portion of the extract was analyzed for ractopamine using ELISA and confirmed by HPLC. For swine complex feeds containing ractopamine at 2.5 to 40 mg/kg, the average recoveries ranged from 73.1 to 86.5% by ELISA and 81.9 to 98.2% by HPLC. For the swine supplement containing ractopamine at 50 to 400 mg/kg, the average recoveries were 105.5 to 111.4% by ELISA and 89.1 to 92.9% by HPLC. The limit of detection was 0.24 microg/g by ELISA and 0.48 microg/g by HPLC, respectively. Results from the swine complex feeds (P = 0.009) and the supplement (P = 0.005) using ELISA and HPLC were not highly correlated. The ELISA was more sensitive and rapid and less expensive than the HPLC method and could be used for ractopamine screening in swine feeds before confirmation and quantification by other methods, such as HPLC.

Evidence against inhibition of sarcoplasmic reticulum Ca2+-pump as mechanism of H2O2-induced contraction of rat aorta

AIM

To test whether inhibition of sarcoplasmic reticulum (SR) Ca2+-pump is involved in H2O2-induced contraction of endothelium-denuded rat aorta.

METHODS

Isometric tension recording of H2O2 and cyclopiazonic acid (CPA)-induced contractions of rat aortic rings were compared in the absence or presence of various pharmacological tools to discriminate their signaling pathways involved.

RESULTS

Both H2O2 and CPA contracted rat aortic rings, but with different contractile patterns. H2O2 triggered a fast and phasic contraction, whereas CPA elicited a slow and sustained contraction. In Ca2+-free medium, pretreatment of aortic rings with CPA 30 micromol/L but not with H2O2 30 micromol/L nearly abolished phenylephrine (10 micromol/L)-induced contraction. In addition, upon the maximal contraction induced by thapsigargin 30 micromol/L, H2O2 but not CPA further contracted aortic rings. On the other hand, H2O2 (30 micromol/L)- but not CPA (10 micromol/L)-induced contraction could be inhibited by suramin and RB-2 (each 100 micromol/L), two P2-purinoceptor antagonists. Furthermore, although pretreatment with 2-APB, a membrane permeable IP3 receptor blocker, inhibited both H2O2- and CPA-induced contractions, only H2O2 (30 micromol/L)-induced contraction could be depressed, to different degree, by various inhibitors of receptor-coupled or downstream signaling enzymes, including PLC, PKC, PLA2, COX, and protein tyrosine kinases.

CONCLUSION

Inhibition of smooth muscle SR Ca2+-pump is unlikely the mechanism responsible for H2O2-induced contraction of endothelium-denuded rat aorta.

Evidence for P(2)-purinoceptors contribution in H(2)O(2)-induced contraction of rat aorta in the absence of endothelium

OBJECTIVE

H(2)O(2) can contract many arteries, however the underlying mechanisms are not fully understood. This study aims to test whether H(2)O(2)-induced vasoconstriction could be functionally attributed to the activation of P(2)-purinoceptors in rat aorta and to explore its possible signaling mechanisms.

METHODS

Isometric tension recording of H(2)O(2) and ATP-induced contractions of rat aortic rings were compared in the absence or presence of various pharmacological tools to identify their possible common signaling pathways.

RESULTS

Both H(2)O(2) and ATP induced transient phasic contractions in a concentration-dependent manner (1-1000 microM). Removal of endothelium potentiated the contractile responses to H(2)O(2) and to ATP. H(2)O(2) (30 microM)-induced phasic contraction could be abolished by catalase (800 U/ml), but not affected by SOD (150 U/ml), DMSO (5 mM) and apyrase (5 U/ml), suggesting no involvement of O(2)(-), hydroxyl free radicals and ATP release. Also, several receptor antagonists including phentolamine, atropine, methysergide and chlorpheniramine (each 3 microM) were without effect on H(2)O(2) (30 microM)-induced phasic contraction, suggesting no involvement of typical neurotransmitter release. However, both H(2)O(2) (30 microM) and ATP (1 mM)-induced phasic contractions not only presented homologous desensitization, but also showed heterogeneous desensitization. Furthermore, the phasic contractions in response to H(2)O(2) (30 microM) or ATP (100 microM) could be inhibited or abolished in a concentration dependent manner by RB-2 and suramin (10-100 microM), two widely used P(2)-purinoceptor antagonists, with only partial inhibition by Evans blue (300 microM), a moderately selective P(2x) receptor blocker, or by alpha-beta-methylene-ATP (100 microM), a selective P(2x) receptor desensitizer. On the other hand, both H(2)O(2) (30 microM) and ATP (100 microM)-induced phasic contractions were also attenuated, to different degree, by inhibitors of several enzymes including PLC, PKC, PLA(2) and cyclooxygenase. Lastly, removal of extracellular Ca(2+) or pretreatment with procaine (10 mM) and dantrolene (30 microM), two putative intracellular Ca(2+) release blockers, or with Ni(2+) (100 microM) and tetrandrine (5 microM), two Ca(2+) channel blockers, all significantly inhibited H(2)O(2) and ATP-induced contractions. However, nifedipine (1 microM), a voltage-dependent L-type Ca(2+) channel blocker, was without effect.

CONCLUSIONS

Our results demonstrate that H(2)O(2)-induced phasic contraction of rat aorta involves, at least in part, the activation of P(2)-purinoceptors in the aortic smooth muscle cells

[The study on the standardization of adults voice acoustic parameters by objective analysis]

OBJECTIVE

To explore the characteristic of normal voice in different age-bracket of Chinese adults and to formulate the normal reference value suited to our country at voice assessment.

METHOD

We divided the adults into the youth, the middle-aged and the old groups, and analyzed normal voice samples with Dr. Speech software and computer multimedia technique and compared the following 5 parameters (Jitter, Shimmer, NNE, Fo and SDFo) of different groups divided according to one's age, sex and vowel.

RESULT

There is difference among the group of age, sex and vowel in most acoustic parameters in the adults.

CONCLUSION

To initiate taking multi-vowels samples and using different normal reference value and multi-parameters analysis according to the difference of age-bracket, sex and vowel in the adults.

Differential contractile actions of reactive oxygen species on rat aorta: selective activation of ATP receptor by H2O2

This study aims to examine the effects of different reactive oxygen species (ROS) on the resting tension of endothelium-denuded rat aortic rings. In these preparations, H2O2 (30 microM) induced a fast and transient contraction, which could be abolished by pretreatment of catalase (800 U/ml), but not affected by superoxide anion scavenger, superoxide dismutase (SOD; 150 U/ml) or the hydroxyl free radical scavenger, DMSO/mannitol (each 3 mM). In contrast, pyrogallol, a putative superoxide anion donor, induced a biphasic contraction, which could be abolished by SOD, but not by catalase or DMSO/mannitol. Unlike H2O2 and pyrogallol, Vitamin C(VitC)/Fe2+ (each 100 microM), a commonly used hydroxyl radical-generating system, triggered a tonic contraction which could be prevented by DMSO/mannitol, but not by SOD or catalase. Interestingly, H2O2-induced contraction could be concentration-dependently (10-100 microM) inhibited by suramin and reactive blue-2 (RB-2), two widely used ATP receptor antagonists. On the other hand, suramin or RB-2, at concentration up to 100 microM, affected neither pyrogallol nor VitC/Fe2+-induced contraction. In conclusion, we showed for the first time that different ROS could contract rat aorta with different mechanisms of action, and H2O2 elicits a transient contraction probably as a result of the ATP receptor activation.

Characteristics of impaired endothelium-dependent relaxation of rat aorta after streptozotocin-induced diabetes

AIM

To study whether impaired endothelium-dependent relaxation (EDR) in early diabetic mellitus in response to different receptor-mediated and nonreceptor-mediated vasodilators ran parallel and its possible mechanism.

METHODS

Isometric tension recording in aortic rings from streptozotocin (Str)-induced diabetic and age-matched nondiabetic rats.

RESULTS

EDR induced by receptor agonist acetylcholine (ACh), histamine (His) or bradykinin (BK) were all significantly reduced in diabetic rings compared with control rings, whereas nonreceptor agonist calcimycin-induced EDR was well reserved in diabetic rings [IC50 control: (0.13 +/- 0.07) mumol.L-1 diabetic: (0.14 +/- 0.06) mumol.L-1, P > 0.05, n = 7]. Cyclopiazonic acid (CPA) which also is a nonreceptor mediated endothelium-dependent vasorelaxant and cells' capacitative Ca2+ entry stimulant, failed to trigger EDR in diabetic rings. Pretreatment with N omega-nitro-L-arginine methylester (L-NAME, 0.3 mmol.L-1) not only abolished all of the EDR elicited by above mentioned vasodilators in either of diabetic or control rings, but also leveled responses triggered by each of the agonists between diabetic and control rings. Upon the maximal EDR induced by ACh (1 mol.L-1) or CPA (3 mumol.L-1) in phenylephrine (1 mumol.L-1) precontracted rings, calcimycin (1 mumol.L-1) further relaxed diabetic rings, but contracted control preparations. When endothelium was denuded, relaxation evoked by sodium nitroprusside and contractions triggered by CPA or His were all identical between diabetic and control rings.

CONCLUSION

Receptor agonists but not nonreceptor agonists-induced EDR are commonly impaired in 4-wk Str-induced diabetic rat aorta, and this defective effect is attributable to the low formation of EDRF/NO which is related to impaired capacitative Ca2+ entry pathway in endothelium.

[Active factors released by endothelial cells in acute leukemia]

In recent years, it is known that endothelial cells play an important role in the genesis of some diseases, but there are only few papers dealing with the role of endothelial cells in leukemia. In this study some of the active factors released by the endothelial cells in patients with acute leukemia such as von Willebrand factor, prostaglandin, fibronectin, tissue-type plasminogen activator and its inhibitor were determined. It was found that the levels of these factors changed significantly in patients with acute leukemia, as compared with those in normal controls, especially in cases with bleeding tendency and infection. The possible mechanism and the clinical significance were discussed.