IRF4 and IRF8 expression are associated with clinical phenotype and clinico-hematological response to hydroxyurea in essential thrombocythemia / 医学前沿

The morbidity and mortality of myeloproliferative neoplasms (MPNs) are primarily caused by arterial and venous complications, progression to myelofibrosis, and transformation to acute leukemia. However, identifying molecular-based biomarkers for risk stratification of patients with MPNs remains a challenge. We have previously shown that interferon regulatory factor-8 (IRF8) and IRF4 serve as tumor suppressors in myeloid cells. In this study, we evaluated the expression of IRF4 and IRF8 and the JAK2V617F mutant allele burden in patients with MPNs. Patients with decreased IRF4 expression were correlated with a more developed MPN phenotype in myelofibrosis (MF) and secondary AML (sAML) transformed from MPNs versus essential thrombocythemia (ET). Negative correlations between the JAK2V617F allele burden and the expression of IRF8 (P < 0.05) and IRF4 (P < 0.001) and between white blood cell (WBC) count and IRF4 expression (P < 0.05) were found in ET patients. IRF8 expression was negatively correlated with the JAK2V617F allele burden (P < 0.05) in polycythemia vera patients. Complete response (CR), partial response (PR), and no response (NR) were observed in 67.5%,10%, and 22.5% of ET patients treated with hydroxyurea (HU), respectively, in 12 months. At 3 months, patients in the CR group showed high IRF4 and IRF8 expression compared with patients in the PR and NR groups. In the 12-month therapy period, low IRF4 and IRF8 expression were independently associated with the unfavorable response to HU and high WBC count. Our data indicate that the expression of IRF4 and IRF8 was associated with the MPN phenotype, which may serve as biomarkers for the response to HU in ET.

Analgesic mechanism of cinobufagin in rats with bone cancer pain / 中草药

Objective: To investigate the analgesic mechanism of cinobufagin in rats with bone cancer pain. Methods: Female SD rats meeting the conditions of pain threshold were selected to construct cancer-induced bone pain (CIBP) model. On the 7th day after modeling, the sham group and the model group were administrated by saline, while the treatment groups were administrated with the low, medium and high concentrations of cinobufagin for consecutive 7 d. The pain behavior (mechanical withdrawal threshold and thermal pain threshold) was tested before modeling and after modeling, and single injection of cinobufagin after 0.5, 1, 2, 4, 6, 8 and 24 h at the first day. The expression of MAPKs protein was detected by Western Blotting, and the content of spinal cytokines (IL-1β, TNF-α, MCP-1) was detected by ELISA. Results: The mechanical pain threshold and thermal pain threshold were significantly decreased in the model group, compared with the sham group (P 0.05). Protein levels of MAPKs were increased in the model group, while the levels of JNK and p38 were decreased in the cinobufagin group (P 0.05). ELISA results showed that cinobufagin significantly decreased the content of cytokines in the spinal cord, when compared with the model group (P < 0.05). Conclusion: Cinobufagin can inhibit the expression of MAPKs proteins in the spinal cord of the rat model with bone cancer pain, ultimately decrease the content of IL-1β, TNF-α, and MCP-1 to alleviate the pain during the process of cancer pain.

The role of high mobility group protein 1 in toluene diisocyanate-induced NLPR3 inflammasome activation in human bronchial epithelial cells / 中国职业医学

OBJECTIVE: To investigate the role of high mobility group protein 1(HMGB1) in toluene diisocyanate(TDI) induced nucleotide-binding oligomerization domain like receptor family pyrin domain-containing 3(NLRP3) inflammasome activation in human bronchial epithelial cells(HBECs). METHODS: i) The TDI-human serum albumin(HSA) stimulation experiment: the HBECs in logarithmic growth phase were randomly divided into control group, low-, medium-and high-dose groups that were pretreated with TDI-HSA with the final concentration of 0.00, 40.00, 80.00 and 120.00 mg/L for 12 hours. ii) The HMGB1 expression inhibition experiment: the HBECs in logarithmic growth phase were divided into control group, TDI-HSA group, TDI-HAS+negative-siRNA group, and TDI-HAS+HMGB1-siRNA group. The cells in TDI-HAS+negative-siRNA group and TDI-HAS+HMGB1-siRNA group were infected with HBECs with negative-siRNA lentivirus and HMGB1-siRNA lentivirus, respectively. Cells in these two groups and the TDI-HSA group were treated with 120.00 mg/L of TDI-HSA for 12 hours. The cells in the control group were not treated with TDI-HAS. iii) The expression of HMGB1, NLRP3, apoptosis-associated speck-like protein containing CARD(ASC), pro-caspase-1 and caspase-1 p20 proteins in all groups were detected by Western blot. The number of NLRP3 and caspase-1 inflammasome in TDI-HSA stimulation experiment was observed by immunofluorescence method. RESULTS: i) TDI-HSA stimulation experiment: the relative protein expression of HMGB1 and ASC was higher in HBECs of medium-and high-dose groups than that of control group(all P values were <0.01). The relative protein expression of NLRP3 and casepase-1 p20 and the number of NLRP3-caspase-1 inflammasome were higher in HBECs of 3 dose groups than that of control group(all P values were <0.01). The number of NLRP3-caspase-1 inflammasome in HBECs increased obviously in low-, medium-and high-dose groups as compared to the control group(all P values were <0.05). The number of NLRP3-caspase-1 inflammasome in HBECs increased with the increase of TDI-HSA dose(all P values were <0.01). ii) The HMGB1 expression inhibition experiment: the relative protein expression of HMGB1, NLRP3, ASC, pro caspase-1 and caspase-1 p20 in HBECs were higher in the TDI-HSA group and TDI-HSA + negative-siRNA group than those of the control group(all P values were <0.01). The above indexes of HBECs were lower in the TDI-HAS + HMGB1-siRNA group than those in the TDI-HSA group and TDI-HSA + negative-siRNA group(all P values were <0.01).CONCLUSION: TDI treatment in HBECS can induce the increase of HMGB1 protein expression and activate NLPR3 inflammasome. Inhibition of HMGB1 expression can down-regulate the expression of NLPR3 and its related proteins.

Zfyve16 regulates the proliferation of B-lymphoid cells / 医学前沿

Zfyve16 (a.k.a. endofin or endosome-associated FYVE-domain protein), a member of the FYVE-domain protein family, is involved in endosomal trafficking and in TGF-β, BMP, and EGFR signaling. The FYVE protein SARA regulates the TGF-β signaling pathway by recruiting Smad2/3 and accelerating their phosphorylation, thereby altering their susceptibility to TGF-β-mediated T cell suppression. Zfyve16 binds to Smad4 and their binding affects the formation of Smad2/3-Smad4 complex in TGF-β signaling. However, the in vivo function of Zfyve16 remains unknown. In this study, we generated a Zfyve16 knockout mouse strain (Zfyve16) and examined its hematopoietic phenotypes and hematopoietic reconstruction ability. The proportion of Tcells in the peripheral blood of Zfyve16 mice increases compared with that in wild-type mice. This finding is consistent with the role of Zfyve16 in facilitating TGF-β signaling. Unpredictably, B cell proliferation is inhibited in Zfyve16 mice. The proliferation potential of Zfyve16 B-lymphoid cells also significantly decreases in vitro. These results suggest that Zfyve16 inhibits the proliferation of T cells, possibly through the TGF-β signaling, but upregulates the proliferation of B-lymphoid cells.

Application of microlecture in practice class of aerospace physiology / 基础医学与临床

Aerospace physiology is an important part of aerospace medicine.There are some problems existing in the current practice classes.Microlecture is a new kind of teaching methods.With its advantages, microlecture improved the teaching efficiency, and played a good role in the practice classes for undergraduate students, successfully solving part of the problems and promoting the teaching reform.The microlecture, as an auxiliary means, provides a new way for practice class of aerospace physiology.It`s suggested to be popularized in undergraduate teaching of aerospace medicine.

Effects of tamoxifen on CD147 glycosylation and MMPs in the diabetic rat myocardium / 中国应用生理学杂志

<p><b>OBJECTIVE</b>Over the last few decades, diabetic cardiomyopathy has been identified as a significant contributor in cardiac morbidity. However, the mechanisms of diabetic cardiomyopathy have not been clarified.</p><p><b>METHODS</b>In the present study, a diabetic rat model was induced by the intraperitoneal injection of streptozotocin. The myocardial CD147 expression and extent of glycosylation, as well as thematrixmetalloproteinases(MMPs) expression and activity, were observed in the diabetic and synchronous rats.</p><p><b>RESULTS</b>The results showed that CD147 located on sarcolemma of cardiomyocytes. The myocardial CD147 expression and glycosylation were significantly increased in the diabetic rats as compared with the control. Expression of MMP-2 protein, MMP-2 and MMP-9 activity were also increased in left ventricular myocardium in the diabetic rats. Tamoxifen only inhibited the enhanced expression of myocardial CD147 in the diabetic rats, but not in synchronous control rats. Tamoxifen inhibited glycosylation of myocardial CD147 in both diabetic and control rats. The inhibition of tamoxifen on CD147 glycosylation was stronger than on the expression in the myocardium. The extent of myocardial CD147glycosylation was positively related toMMP-2 and MMP-9 activity. Tamoxifen induced an inhibition of myocardial MMP-2 and MMP-9 activity in the control and diabetic rats.</p><p><b>CONCLUSION</b>These results indicate that myocardial CD147 expression, especially the extent of glycosylation, regulates MMP-2 and MMP-9 activity, then accelerates cardiac pathological remodeling inducing diabetic cardiomyopathy. Tamoxifen inhibits myocardial CD147 glycosylation and further depress the activity of MMPs. Therefore, tamoxifen may protect the diabetic rats against diabetic myocardium.</p>

Dynamic assembly of intercalated disc during postnatal development in the rat myocardium / 生理学报

The intercalated disc (ICD) complex of cardiomyocyte consists of fascia adherens, desmosomes and gap junctions which are mainly constructed by their transmembrane proteins: N-cadherin (N-cad), desmoglein-2 (DSG2) and connexin 43 (Cx43), respectively. The aim of this study was to observe the dynamic changes in colocalization of N-cad, DSG2 and Cx43 with each other in the rat left ventricular myocardium at 1, 7, 14, 28 and 90 day(s) after birth (P1, P7, P14, P28 and P90) using immunofluorescent staining. The results showed that, N-cad, DSG2 and Cx43 located all around the plasma membrane at the P1. These proteins accumulated to the long ends of cardiomyocytes, indicating preliminary formation of the ICD at the P7. The localization of three proteins at the ICD increased progressively, but their lateral localization showed an inverse trend from the P14 to P90. However, Cx43 still kept a certain amount of lateral localization in cardiomyocytes even at the P90 as compared with N-cad and DSG2. Quantitative colocalization of proteins was analyzed by the stereological method. Total percentage of colocalization of N-cad with DSG2 was 33.5% at the P1, and increased to 38.6% at the P7, 9.4% in ICD and 29.2% in lateral side. The total percentage of colocalization of N-cad with DSG2 increased to 65.7% at the P90, ICD colocalization increasing to 60.5% and lateral colocalization decreasing to 5.2%. Total percentage of colocalization of N-cad with Cx43 increased from 10.3% at the P1 to 37.1% at the P90, and only ICD colocalization increased, but lateral colocalization kept about 5%. The colocalization pattern of DSG2 with Cx43 was similar to that of N-cad with Cx43. Total percentage of colocalization of N-cad with DSG2 was higher than those of N-cad or DSG2 with Cx43. The above results suggest that the formation of mechanical junctions at the ICD of cardiomyocyte is prior to that of electrochemistry junctions during postnatal development. In other words, cardiomyocyte growth needs a stable mechanical environment at first.

In vitro heart models simulating in vivo cardiac ischemia-reperfusion injury / 生理学报

The aim of this study was to compare in vivo and several in vitro cardiac ischemia-reperfusion (I-R) myocardial injury models, and choose a superior in vitro cardiac I-R model. Sprague-Dawley (SD) rats were randomly grouped into in vivo, Langendorff, Langendorff + pacing, and working heart groups. Left anterior descending (LAD) coronary artery was ligated for 60 min and then reperfused for 120 min in in vivo and in vitro rat hearts. Cardiac function and myocardial infarct size were measured by using pressure transducer and TTC/Evans blue double staining, respectively. The results showed that heart rate was greater in in vivo model than those in the three in vitro models. Coronary flows were dropped after LAD ligation and could recover at early phase of releasing LAD ligation in I-R models of the isolated working heart, Langendorff and Langendorff with 300 beats/min of electrical stimulation. Left ventricular end-systolic pressure (LVESP) decreased during ischemia, and partially restored during reperfusion in the three in vitro models. Left ventricular end-diastolic pressure (LVEDP) increased during ischemia in the three in vitro models. LVEDP was significantly higher in the isolated working heart than those in Langendorff models during ischemia, whereafter decreased slowly during reperfusion. LVEDP elevated further in the initiation of reperfusion period and then decreased, but did not recover to normal levels during reperfusion in Langendorff and Langendorff + pacing groups. Left ventricular myocardial infarct size was (60.4 ± 5.4)% in in vivo I-R model, which was significantly higher than that in Langendorff model and the isolated working heart. Notably, there was no significant difference in myocardial infarct size between in vivo model and Langendorff model with electrical stimulation. These results suggest that Langendorff I-R model with 300 beats/min of electrical stimulation can simulate the in vivo I-R myocardial injury.

The clinical study of percutaneous transhepatic radiofrequency ablation combined with tumor edge of percutaneous absolute ethanol injection on liver cancer adjacent to major blood vessels / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To explore the effects of percutaneous transhepatic radiofrequency ablation (PRFA) combined with tumor edge of percutaneous absolute ethanol injection (PEI) on liver cancer adjacent to major blood vessels.</p><p><b>METHODS</b>Seventy five patients with liver cancer adjacent to major blood vessels were randomly divided into two groups: PRFA+PEI therapy group (38 cases) and PRFA control group (37 cases). Tumor necrosis rate, AFP levels, local recurrence rate, median for survival time and cum survival were used as the evaluation index to evaluate the efficacies of the two methods.</p><p><b>RESULTS</b>Tumor necrosis rates of the therapy group and the control group were 84.2% and 54.1% (P < 0.01), respectively; AFP levels of therapy group and control group at 1, 3, 6 and 12 months after treatment were (105.0 ± 35.5) μg/L, (28.4 ± 4.3) μg/L, (58.6 ± 6.7) μg/L, (89.5 ± 12.5) μg/L and (137.2 ± 34.6) μg/L, (84.2 ± 18.4) μg/L, (106.6 ± 20.3) μg/L, (173.7 ± 32.0) μg/L, respectively. The rates of therapy group was significantly lower than of control group. Local recurrence rates of the therapy group and control group were 2.6%, 7.9%, 13.2% and 31.6% vs 10.8%, 21.6% , 40.5% and 62.1% (P < 0.05) at 3, 6, 12 and 24 months after treatment, respectively. Median for survival time of the therapy group and control group were 28.0 ± 2.8 months and 19.0 ± 3.6 months, respectively. Cum survival of the therapy group and control group were 84.2%, 78.9%, 60.5% and 31.6% vs 78.4%, 67.6%, 37.8% and 8.1% (P < 0.05) at 6, 12, 24 and 36 months after treatment, respectively.</p><p><b>CONCLUSION</b>PEI as a supplementary treatment of PRFA can effectively improve the treatment of liver cancer adjacent to major blood vessels and significantly reduce the local recurrence rate and improve long-term survival rates.</p>

Generation of glyco-engineered BY2 cell lines with decreased expression of plant-specific glycoepitopes

Plants are known to be efficient hosts for the production of mammalian therapeutic proteins. However, plants produce complex N-glycans bearing β1,2-xylose and core α1,3-fucose residues, which are absent in mammals. The immunogenicity and allergenicity of plant-specific Nglycans is a key concern in mammalian therapy. In this study, we amplified the sequences of 2 plant-specific glycosyltransferases from Nicotiana tabacum L. cv Bright Yellow 2 (BY2), which is a well-established cell line widely used for the expression of therapeutic proteins. The expression of the endogenous xylosyltranferase (XylT) and fucosyltransferase (FucT) was downregulated by using RNA interference (RNAi) strategy. The xylosylated and core fucosylated N-glycans were significantly, but not completely, reduced in the glycoengineered lines. However, these RNAi-treated cell lines were stable and viable and did not exhibit any obvious phenotype. Therefore, this study may provide an effective and promising strategy to produce recombinant glycoproteins in BY2 cells with humanized N-glycoforms to avoid potential immunogenicity.

The influence of contraction modes on the phosphorylation of p38/Akt / 中国应用生理学杂志

<p><b>OBJECTIVE</b>Muscle contraction may prompt glucose uptake through non-insulin-dependent ways, and it may be due to the enhanced activation of key proteins known to regulate glucose metabolism, like p38 and Akt. Our experiment focused on the impact of different contraction modes on the phosphorylation of the molecules, thus to explore effective ways to lower blood glucose.</p><p><b>METHODS</b>Isolated muscle strips perfusion technique and Western blot analysis were employed to investigate the influence of different modes of contraction on the activation of the molecules.</p><p><b>RESULTS</b>Muscle contraction led to an increase in p38 phosphorylation, with the greatest effect observed after 5 minutes of 10% DC (duty cycle) contraction and 5 minutes of 1% DC contraction. However, phosphorylation of Akt were not altered by the two contraction modes.</p><p><b>CONCLUSION</b>The level of phosphorylation of p38 was higher at the optimal contraction modes, but these modes could not increase the level of phosphorlation of Akt.</p>

Protective effects of EPA and DHA on lipopolysaccharide-stimulated rat mesangial cells / 中国病理生理杂志

AIM: To investigate the effects of EPA and DHA on oxidative stress of lipopolysaccharide-stimulated rat mesangial cells. METHODS: The glomerular mesangial cells (GMCs) were stimulated by lipopolysaccharide (LPS) and incubated with EPA (10 μmol/L or 100 μmol/L) and DHA (10 μmol/L or 100 μmol/L) for 24 h, 48 h and 72 h. The activity of SOD, GSH-Px and the level of MDA was measured. The protein and mRNA expressions of MCP-1 and TGF-β_1 were detected by immunocytochemistry and real-time PCR method, respectively. RESULTS: The activities of SOD and GSH-Px were decreased and the concentration of MDA was increased when stimulated with LPS. EPA and DHA increased the activities of SOD and GSH-Px and decreased the concentration of MDA significantly. Meanwhile, the protein and mRNA expressions of MCP-1 and TGF-β_1 stimulated by LPS were decreased. DHA was more effective than EPA at the same concentration. CONCLUSION: EPA and DHA enhance the activities of antioxidant enzymes, decrease the concentration of MDA and inhibit the expression of TGF-β_1 and MCP-1, suggesting that the protective effect of EPA and DHA on kidney is related to the antioxidation and the inhibition of TGF-β_1 and MCP-1 expression.

Probucol inhibits proliferation of rat aortic smooth muscle cells stimulated with oxidized low-density lipoprotein / 中国病理生理杂志

AIM: To investigate the relationships between antiproliferative mechanisms of probucol and protein expressions of signaling molecules ERK1/2, MKP-1, HO-1 and Trx-1 in rat aortic smooth muscle cells (RASMCs) stimulated with ox-LDL. METHODS: The effects of probucol on cell cycle, cell proliferation and the expressions of ERK1/2, MKP-1, HO-1 and Trx-1 in the presence of ox-LDL were observed by means of MTT test, FCM and Western blotting. RESULTS: (1) Probucol significantly inhibited the proliferation of RASMCs stimulated with ox-LDL. A value in 100 μmol/L probucol+35 mg/L ox-LDL group was reduced by 34.9% as compared to ox-LDL group (P<0.01). (2) Probucol protected against ox-LDL-induced RASMCs proliferation through inducing cell growth arrest at G_0/G_1 phase and cell apoptosis. (3) ox-LDL increased the expression of p-ERK1/2 by 34.7% (P<0.01) and decreased MKP-1 by 60.0% (P<0.01), respectively, as compared to control. Probucol attenuated the increase in ox-LDL-stimulated p-ERK1/2 level by 15.7%, but increased MKP-1 expression by 2 times (P<0.01). (4)ox-LDL at concentration of 35 mg/L decreased the intracellular Trx-1 expression by 28.9% (P<0.05), and slightly increased the level of HO-1 expression as compared to control (P<0.05). Probucol enhanced the expression of Trx-1 by 91.6% (P<0.01) and HO-1 by 31.9% (P<0.01), respectively as compared to ox-LDL group. CONCLUSION: Probucol inhibits ox-LDL-stimulated the proliferation of RASMCs through increases in MKP-1/HO-1 expression, suppression of cell cycle progression and induction of cell apoptosis.

Calcium leak of sarcoplasmic reticulum induces degradation of troponin I in skeletal muscle fibers / 生理学报

The troponin I subunit (TnI) was used as a molecular marker to explore the relationship between the resting intracellular Ca(2+) concentration and myofibril degradation in muscle fibers. The isolated soleus muscle strips of rats were treated by caffeine and H2O2. Caffeine is an opener to increase the calcium release channel open probability of sarcoplasmic reticulum (SR) in contraction phase. H2O2 induces a calcium leak of SR calcium release channel in relaxation phase. The expression and degradation of TnI were detected by Western blot. The resting tension of tetanic contraction and expression of TnI were not changed, but the developed tension was lowered in isolated soleus muscle strips during 40 min of calcium-free Krebs perfusion. Low concentrations of caffeine (1 and 5 mmol/L) perfusion induced a transient increase in resting tension during fatigue period, but did not alter the extent of fatigue, recovery rate after fatigue and expression of TnI in muscle strips. High concentration of caffeine (10 mmol/L) perfusion induced a progressive increase in resting tension, a higher rate of fatigue and a decrease in recovery rate after fatigue in muscle strips. There was a detectable degradation of TnI in soleus after 10 mmol/L caffeine treatment. H2O2 perfusion facilitated a progressive increase in resting tension in a dose-dependent manner, but did not influence the fatigue rate of tetanic contraction. The recovery rate after fatigue showed a quick resumption before decline during H2O2 perfusion. Degradation of TnI occurred in 5 and 10 mmol/L H2O2-treated soleus muscles. Since resting tension is dependent on intracellular Ca(2+) concentration, the above-mentioned results suggest that SR Ca(2+) leakage in relaxation phase may induce a degradation of TnI in skeletal muscle fibers.

Increased activity of sarcoplasmic reticulum Ca(2+)-ATPase in soleus of hyperthyroid rat accelerates fatigue during intermittent tetanic contraction / 生理学报

The elevated plasma level of thyroxin and/or triiodothyronine in hyperthyroidism not only induces a transition from the innervated slow-twitch muscle fibers to fast-twitch fibers, but also changes the contractile function in transition muscle fibers. So the muscle weakness of thyrotoxic myopathy would relate to alteration in fatigability of tetanic contraction in muscles, especially in slow-twitch fibers. The aim of the present study was to observe the extent of fatigue of soleus in 4-week hyperthyroid rats and elucidate its underlying mechanism. The isolated soleus muscle strips were perfused in Krebs-Henseleit solution with or without an inhibitor of sarcoplasmic reticulum Ca(2+)-ATPase (SERCA), cyclopiazonic acid (CPA). The contractile function of soleus was observed in twitch and intermittent tetanic contraction. The body weight in 4-week hyperthyroid rats decreased as compared with that in the control group [(292±13) g vs (354±10) g], but there was no difference between hyperthyroid and control groups in the wet weight of soleus [(107.3±8.6) mg vs (115.1±6.9) mg]. The time to peak tension (TPT) and time from peak tension to 75% relaxation (TR(75)) in twitch contraction were shortened in the soleus of hyperthyroid rats, and the TR(75) of tetanic contraction was also shortened as compared with that in the control group [(102.8±4.1) ms vs (178.8±15.8) ms]. The optimal stimulation frequency at which a maximal tension of tetanic contraction happened was shifted from 100 Hz in the control group to 140 Hz in hyperthyroid group. The soleus of hyperthyroid rat was easier to fatigue than that of the control rat during intermittent tetanic contraction. The SERCA activity also increased in soleus of hyperthyroid rat. The TR(75) in tetanic contraction was prolonged and showed an increased fatigue resistance in the soleus of control and hyperthyroid groups treated with 1.0 μmol/L CPA. The fatigue resistance of tetanic contraction in the soleus of hyperthyroid rat increased further with 5.0 μmol/L CPA treatment, but the resting tension kept rising. The 10 μmol/L CPA reduced the fatigue resistance of tetanic contraction in the soleus of hyperthyroid rat. The above results demonstrate that the SERCA activity in soleus can also influence the relaxation duration of twitch contraction like that in the myocardium. The SERCA activity in slow-twitch fibers is possibly involved in the regulation of fatigue resistance of intermittent tetanic contraction.

Factors modulating recovery rate after intermittent tetanic fatigue in atrophic soleus / 生理学报

Fatigue occurs when the interval of intermittent tetanic contraction of skeletal muscle is shortened to a certain degree and the contractile tension declines. After fatigue, prolongation of the contraction interval can make the contractile tension recover. In atrophic soleus, the recovery rate is slower. It has been shown that a decrease in the contractile tension is caused by the inhibition of the myofibrils and sarcoplasmic reticulum Ca(2+) release channels during fatigue. So the mechanism of the recovery of contractile tension is the recovery of the inhibited myofibrils and sarcoplasmic reticulum Ca(2+) release channels. But how the inhibition affects the recovery course is still unclear. To specify the factors modulating the recovery rate after intermittent tetanic fatigue in soleus, and to seek the reasons for the decrease in recovery rate in atrophic soleus, we observed the recovery time course of different types of fatigue in isolated soleus muscle strips. The 10% or 50% decrease in the maximal tetanic contractile tention (P(0)) was defined respectively as slight or moderate fatigue. After short-term (S10P, 10 s) and long-term (L10P, 300 s) slight fatigue, the tetanic contractile tension recovered to nearly 100% P(0) at the 20th minute. In both slight fatigue groups, perfusion with 10 mumol/L of ruthenium red (an inhibitor of Ca(2+) release channels in sarcoplasmic reticulum) slowed down the recovery rate. It was suggested that slight fatigue only induced inhibition of myofibrils. After short-term (S50P, 60 s) or long-term (L50P, 300 s) moderate fatigue, the tetanic contractile tension at the 20th minute recovered to about 95% P(0) in S50P group and 90% P(0) in L50P group, respectively. The recovery rate in L50P group was significantly lower than that in S50P group. So the recovery rate after moderate fatigue was related to the tetanic contraction duration. In both moderate fatigue groups, perfusion with 5 mmol/L of caffeine (an opener of Ca(2+) release channels in sarcoplasmic reticulum) resulted in nearly 100% recovery at the 5th minute. It was suggested that moderate fatigue induced inhibition of myofibrils and sarcoplasmic reticulum Ca(2+) release channels. In 1-week tail-suspended rats, soleus muscles showed a 40% of atrophy. After slight fatigue, the tetanic contractile tension in unloaded soleus recovered to 94% P(0) in S10P group and 95% P(0) in L10P. After moderate fatigue, the tetanic contractile tension in unloaded soleus recovered to 92% P(0) in S50P and 84% P(0) in L50P at the 20th minute. There were significant decreases in all of the fatigue groups as compared with the control groups. These results suggest that both slight and moderate fatigue inhibit the myofibrils and sarcoplasmic reticulum Ca(2+) release channels in 1-week unloaded soleus, so the recovery rate after tetanic fatigue is slower than that in the control group.

Inhibition of probucol on the apoptosis of vascular smooth muscle cell induced by hydrogen peroxide / 中国药理学通报

Aim To investigate the effects of antioxidant probucol on vascular smooth muscle cells(VSMCs) apoptosis induced by H2O2.Methods H2O2 (1 mmol?L-1) was used to induce VSMCs apoptosis.The VSMCs were treated with probucol(100,10,1 ?mol?L-1) for 6 hours.For the evaluation of apoptosis,Annexin V-FITC staining,Hoechest33258 staining and the TUNEL assay were used.The expressions of ASK-1 and Trx-1 were detected by Western blot analysis.Results H2O2 could promote the apoptosis of VSMCs,increase the expression of ASK-1 and decrease the expression of Trx-1.Probucol could attenuate the apoptosis induced by H2O2 in a dose-dependent,down-regulate ASK-1 expression and increase Trx-1 expression.Conclusion Probucol can antagonize the apoptosis of VSMCs induced by H2O2.The mechanism may be correlated with a decreased expression of ASK-1 and an increased expression of Trx-1.

Effect of glycol mannate sulfate on experimental thrombosis / 中国药理学通报

AIM　To investigate the antithrobosis effects of glycol mannate sulfate(GMS). METHODS　Vein thrombus was formed in rat by ligating postcava. Thrombus formation in vitro was observed by Chandlers method. Clotting indexes were measure by ACL200 congulation system. RESULTS　GMS dosage of 20、40 mg*kg-1 could inhibit the vein thrombus formation in rats (P<0.01). GMS could inhibit the thrombosis in rabbit, in vivo, and the inhibitory action was enhanced along with the increase of dosage. The CT,TT,CT,APTT,RT and PT were prolonged, and the fibrinogen and the activity of Ⅱ and Ⅱa were decreased. The activity of ATⅢ was enhenced. CONCLUSION　GMS has antithrombotic effect and the mechanism may be related to the anticongulat effect.

Changes of shortening amplitude-frequency relationship in hyperthyroid rat cardiomyocytes / 中国病理生理杂志

AIM: The aim of this study was to observe the cardiac performance in 2-week or 4-week levothyroxine(T4)-induced cardiac hypertrophy and to elucidate the possible underlying mechanism of cardiac hypertrophy transition to heart failure in T4 treatment rats.METHODS: The blood pressure and pulse rate were measured by tail-cuff technique.The cardiac output and the preload-cardiac output were measured in working heart mode.The shortening of unloading contraction in cardiomyocytes was observed by an edge-detector system.RESULTS: Resting heart rate in T4 treatment rats increased significantly and the width of cardiomyocytes widened in T4 rats,but the length of cardiomyocytes had no difference compared with control values.The cardiac output in 2-week T4 group was higher than that in control group.The cardiac output increased when the preload increased from 5 mmHg to 15 mmHg.The unloading shortening amplitude at 1 Hz and 2 Hz increased in 2-week T4 group.No difference between 2-week T4 group and control group at 4 Hz was observed.When the stimulating frequency increased from 1 Hz to 4 Hz,the shortening amplitude also increased in control cardiomyocytes,but decreased in 2-week or 4-week T4 group.The shortening amplitude increased further in 4-week T4 group as compared with that in control.The time to peak shortening and time from peak shortening to 75% relaxation reduced at each frequency in 2-week and 4-week T4 group.The shortening and relaxation rates in 2-week or 4-week T4 group were higher than those in control group at 1 Hz and 2 Hz.The shortening and relaxation rate kept higher at 4 Hz in 2-week T4 group,but showed no difference with control at 4 Hz in 4-week T4 group.CONCLUSION: These above results suggest that shortening amplitude-frequency relationship of cardiomyocytes in 4-week T4 rats is earlier to be altered than cardiac performance in working heart.

EXPERIMENTAL STUDIES ON ANTITHROMBOSIS OF EICOSAPENTAENOIC ACID / 中国海洋药物

The effects of eicosapentaenoic acid (EPA) on experimental thrombosis and its mechanism were studied. The results showed that eicosapentaenoic acid had a significant antithrombolic effect both in vivo and in vitro . EPA also had a fibrinolytic activity and can shorten euglobulin lysis time. Our studies also showed that EPA can inhibit platelet aggregation in rats. The plasma concentration of 6-keto-PGF1a and TXB2 was measured by radioimmunoassay. The results showed that EPA can reduce the contents of TXB2 and raise 6-keto-PGF1a/TXB2 ratio.