[The distribution of musk and river deer in local chronicles in Guizhou]

Some information and records about musk (She, ) and river deer (Zhang, /) can be found in local chronicles or documents in Guizhou. They were taken as the same species in terms of a medicinal animal. The records for their living areas in Guizhou were neither clear nor in detail in the Ming Dynasty, but were specific in the Qing Dynasty and more concise in the period of the Republic of China. The living areas for musk and river deer reduced from the Ming Dynasty to the Republic of China. Such change was believed to be the result of the natural environment and the social factors as well, such as the reclamation of mountain areas in Guizhou, the reduction of forests, and the demand and resulting exorbitant prices that led to excessive hunting.

Analysis of international competitiveness of the China's licorice industry from the perspective of global trade

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice is a multi-purpose plant raw material, which is widely used in the pharmaceutical industry and food industry, cosmetic industry, etc. It has a wide application in various countries and regions around the world.

AIM OF STUDY

This paper studied the trade situation of licorice-related products among major countries and regions in the world, providing a practical reference for the sustainable development of the global licorice industry.

MATERIALS AND METHODS

The licorice trade data of licorice-related products came from the United Nations Commodity Trade Database and China Customs data. We analyzed the world's major trading countries by using international market share (IMS), trade competitiveness index (TC), average export price (AEP) and average import price (AIP), and analyzed global trade flows with chord diameter.

RESULTS

Uzbekistan, Kazakhstan and Iran mainly export licorice raw materials and low value-added products. China is both a producer and a consumer of licorice raw materials and licorice products. The processing trade of the licorice industry in China has advantages, and the structure of import and export trade has been continuously improved. The United States, France, Germany and other developed countries are still important consumers who rely on the intellectual property rights and brand advantages of licorice products, which have stronger global trade radiation capacity.

CONCLUSIONS

China's trade structure has been optimized and its industrial competitiveness has been enhanced. China's experience can be used for reference by other countries, especially those with rich licorice resources among the SCO members.

Fasting improves tolerance to acute hypoxia in rats

Acute high-altitude illness seriously threatens the health and lives of people who rapidly ascend to high altitudes, but there is currently no particularly effective method for the prevention or treatment of acute high-altitude illness. In the present study, we found that fasting preconditioning effectively improved the survival rate of rats exposed to a simulated altitude of 7620 m for 24 h, and a novel animal model of rapid adaptation to acute hypoxia was established. Compared with control treatment, fasting preconditioning activated AMPK, induced autophagy, decreased ROS levels, and inhibited NF-κB signaling in the cardiac tissues of rats. Our results suggested that fasting effectively improved the acute hypoxia tolerance of rats, which was gradually enhanced with prolongation of fasting. In addition, the acute hypoxia tolerance of young rats was significantly higher than that of adult rats. These experimental results lay the foundation for achieving rapid adaptation to acute hypoxia in humans.

[Association between sleep and prevalence of hypertension in elderly population]

Objective: To explore the association between sleep duration, sleep quality and the prevalence of hypertension in the elderly aged 65 years and above. Methods: This study was conducted among the elderly in communities in Yiwu, China from April to July, 2019, and participants were recruited through physical examination in the hospital. Face-to-face interview was performed to obtain basic information. Sleep duration and sleep quality were evaluated by Pittsburgh Sleep Quality Index (PSQI). Associations between sleep duration, sleep quality and hypertension were evaluated by multivariate logistic regression analysis. Results: A total of 3 169 elderly persons, aged ≥65 years old, were included in the study. The overall prevalence of hypertension was 50.8%. The elderly with very poor sleep quality and short sleep duration accounted for 22.4% and 28.5%, respectively. After adjusting for demographic characteristics, socioeconomic status, lifestyle and health status, the OR of hypertension for the elderly with very poor sleep quality was 1.42 (95%CI: 1.12-1.80) compared with those with very good sleep quality. Compared with the elderly with sleep duration of 6-7 h a night, the OR of hypertension for those with sleep duration <6 h was 1.37 (95%CI: 1.15-1.65). As the sleep quality decreased, the risk for hypertension increased. An U-shaped association was found between sleep duration and risk of hypertension. Subgroup analyses showed that this association existed in both men and women, but only significant in the elderly aged <75 years. Conclusion: Poor sleep quality and short sleep duration were associated with risk for hypertension in the elderly.

Elevated ROS depress mitochondrial oxygen utilization efficiency in cardiomyocytes during acute hypoxia

Mitochondria are important sites for the production of ATP and the generation of ROS in cells. However, whether acute hypoxia increases ROS generation in cells or affects ATP production remains unclear, and therefore, monitoring the changes in ATP and ROS in living cells in real time is important. In this study, cardiomyocytes were transfected with RoGFP for ROS detection and MitGO-Ateam2 for ATP detection, whereby ROS and ATP production in cardiomyocytes were respectively monitored in real time. Furthermore, the oxygen consumption rate (OCR) of cardiomyocytes was measured. Similar results were produced for adult and neonatal rat cardiomyocytes. Hypoxia (1% O₂) reduced the basal OCR, ATP-linked OCR, and maximal OCR in cardiomyocytes compared with these OCR levels in the cardiomyocytes in the normoxic group (21% O₂). However, ATP-linked OCR, normalized to maximal OCR, was increased during hypoxia, indicating that the electron leakage of complex III exacerbated the increase of ATP-linked oxygen consumption during hypoxia and vice versa. Combined with the result that cardiomyocytes expressing MitGO-Ateam2 showed a significant decrease in ATP production during hypoxia compared with that of normoxic group, acute hypoxia might depress the mitochondrial oxygen utilization efficiency of the cardiomyocytes. Moreover, cardiomyocytes expressing Cyto-RoGFP or IMS-RoGFP showed an increase in ROS generation in the cytosol and the mitochondrial intermembrane space (IMS) during hypoxia. All of these results indicate that acute hypoxia generated more ROS in complex III and increased mitochondrial oxygen consumption, leading to less ATP production. In conclusion, acute hypoxia depresses the mitochondrial oxygen utilization efficiency by decreasing ATP production and increasing oxygen consumption as a result of the enhanced ROS generation at mitochondrial complex III.

Crystal structure of cyclo[diaqua-bis(μ2-3′,5-dicarboxy-[1,1′-biphenyl]-3,4′-dicarboxylato-κ4 O,O′:O′′,O′′′)-bis(4,4′-bis(pyrid-4-yl)biphenyl-K1 N)dicadmium(II)], C76H52Cd2N4O18

C76H52Cd2N4O18, triclinic, P1̄ (no. 2), a = 8.5834(4) Å, b = 10.7034(5) Å, c = 17.6105(8) Å, α = 99.328(4)°, β = 100.580(4)°, γ = 95.281(4)°, V = 1556.94(13) Å3, Z = 1, R gt(F) = 0.0477, wR ref(F 2) = 0.1183, T = 293(2) K.

[Evaluation of human milk feeding in hospitalized very low and extremely low birth weight infants]

Objective: To investigate the current situation of human milk (HM) feeding in hospitalized very low and extremely low birth weight infants. Methods: The study retrospectively extracted the data of 601 infants with birth weight <1 500 g, and admitted within 24 hours after birth to the Neonatal Intensive Care Unit of Nanjing Maternity and Child Health Care Hospital from January 2016 to December 2018. The infants were grouped into exclusive mother's-own-milk (MOM) group, donor human milk (DHM) group (partial or none MOM), and mixed (HM and formula) feeding group according to the feeding strategy. Qualitative and quantitative variables in the three groups were compared with One-way ANOVA, Kruskal-Wallis test, Chi-square test or Fisher exact test. Kappa and McNemar test were used for consistency testing. Results: Among the 601 infants (309 boys and 292 girls), 6 (1.0%) infants had never been fed with MOM. The gestational age and birth weight were (29.3±1.9) weeks and 1 260(1 115, 1 400) g in 601 infants. A total of 8 (1.3%) infants were grouped into MOM group, 542 (90.2%) were grouped into DHM group, and 51 (8.5%) were grouped into mixed feeding group. The percentage of enteral feedings with MOM in the stage of hospitalization 1-7 d, 8-14 d and 15-28 d were 73.6% (42.9%, 86.7%), 97.5% (78.6%, 100.0%) and 99.3% (93.0%, 100.0%), respectively (H=414.95, P<0.01), and the pairwise comparison suggested that the stage of hospitalization 1-7 d was the lowest (adjusted both P<0.05). The average weight adjusted daily dose of MOM were 9.7 (4.3, 18.2), 59.1 (26.5, 93.5) and 116.0 (60.3, 142.6) ml/(kg·d) in the stage of hospitalization 1-7 d, 8-14 d and 15-28 d, respectively (H=759.75, P<0.01), and the pairwise comparison suggested that the stage of hospitalization 1-7 d was the lowest (adjusted both P<0.05). The weight adjusted daily dose of MOM in exclusive MOM group, DHM and Mixed feeding group were 95.2 (40.0, 117.2), 82.9(53.6, 103.1) and 55.7 (16.6, 97.5) ml/(kg·d), respectively (H=10.78, P=0.005).Additionally, the percentage and weight adjusted daily dose of MOM showed a general consistency of 0.703 (P>0.05, Kappa=0.408). Conclusions: The rate of exclusive MOM feeding is low, especially during the first 7 days of hospitalization. The percentage of total enteral feedings with MOM and the average weight adjusted daily dose of MOM can well evaluate the situation of HM feeding during hospitalization quantitively.

[Disparity of minnesota multiphasic personality inventory between positions and its relationship with job burnout in a general hospital]

Objective: To explore the difference of personality characteristics of physicians, nurses, medical skills and administrative personnel in a general hospital and its influence on job burnout. Methods: Employee entered the hospital before 2018 were enrolled in the current study and the position was classified as physicians, nurses, medical technician and administrative staff. Minnesota Multiphasic Personality Inventory (MMPI) was completed by the employee at the time of entering the hospital. Status of job burnout was assessed in 2018 using the Maslach Burnout Inventory-General Survey (MBI-GS) . Results: Physicians have a higher rate of paranoia than others (P<0.05) , and administrative staff and medical technician have a slightly higher score than the other two categories of people (P<0.05) , and administrators lie at a higher rate than others (P<0.05) . Further analysis found that personality traits did not have a significant association with job burnout at the time of entry. Conclusion: The administrative and medical staff is slightly more irritable, the administrative staff lying slightly higher score, the staff after the entry of job burnout is not affected by the personality characteristics of the onboarding.

Comparison of hypoxic effects induced by chemical and physical hypoxia on cardiomyocytes

The degree and duration of chemical hypoxia induced by sodium dithionite (Na₂S₂O₄) have not been reported. It is not yet clear how much reduction in the O₂ concentration (physical hypoxia) can lead to hypoxia in cultured cardiomyocytes. In this study, oxygen microelectrodes were used to measure changes in the O₂ concentration in media containing different concentrations of Na₂S₂O₄. Then, hypoxic effects of 0.8, 1.0, and 2.0 mM Na₂S₂O₄ or 1%, 3%, and 5% O₂ in cultured cardiomyocytes from neonatal rats were observed and compared. The results showed that the O₂ concentration failed to remain constant by Na₂S₂O₄ treatment during the 180-minute observation period. Only the 2.0 mM Na₂S₂O₄ group significantly increased the expression of hypoxia-inducible factor 1α (HIF-1α) and hypoxic responses. Notably, 3% O₂ only significantly increased the expression of HIF-1α in cardiomyocytes, while 1% O₂ not only increased the expression of HIF-1α but also increased the apoptotic rate in cardiomyocytes. These results suggest that Na₂S₂O₄ is not suitable for establishing a hypoxic model in cultured neonatal rat cardiomyocytes, and neonatal rat cardiomyocytes cultured at or below 1% O₂ induced significant hypoxic effects, which can be used as a starting O₂ concentration for establishing a hypoxic cell model.

Mitochondrial electron transport chain, ROS generation and uncoupling (Review)

The mammalian mitochondrial electron transport chain (ETC) includes complexes I-IV, as well as the electron transporters ubiquinone and cytochrome c. There are two electron transport pathways in the ETC: Complex I/III/IV, with NADH as the substrate and complex II/III/IV, with succinic acid as the substrate. The electron flow is coupled with the generation of a proton gradient across the inner membrane and the energy accumulated in the proton gradient is used by complex V (ATP synthase) to produce ATP. The first part of this review briefly introduces the structure and function of complexes I-IV and ATP synthase, including the specific electron transfer process in each complex. Some electrons are directly transferred to O₂ to generate reactive oxygen species (ROS) in the ETC. The second part of this review discusses the sites of ROS generation in each ETC complex, including sites I_F and I_Q in complex I, site II_F in complex II and site III_Qo in complex III, and the physiological and pathological regulation of ROS. As signaling molecules, ROS play an important role in cell proliferation, hypoxia adaptation and cell fate determination, but excessive ROS can cause irreversible cell damage and even cell death. The occurrence and development of a number of diseases are closely related to ROS overproduction. Finally, proton leak and uncoupling proteins (UCP_S) are discussed. Proton leak consists of basal proton leak and induced proton leak. Induced proton leak is precisely regulated and induced by UCPs. A total of five UCPs (UCP1-5) have been identified in mammalian cells. UCP1 mainly plays a role in the maintenance of body temperature in a cold environment through non-shivering thermogenesis. The core role of UCP2-5 is to reduce oxidative stress under certain conditions, therefore exerting cytoprotective effects. All diseases involving oxidative stress are associated with UCPs.

Effects of polyethylene glycol electrolyte powder combined with different agents in bowel preparation for colonoscopy in elderly patients with constipation

AIM

To evaluate the effects of polyethylene glycol electrolyte powder combined with different agents in bowel preparation for colonoscopy examination in elderly constipation patients.

METHODS

A total of 108 elderly patients with constipation who would undergo bowel preparation for colonoscopy were enrolled from March 2016 to May 2017, and they were prospectively randomized into three groups: A, B, and C (n = 36 each). Patients of group A only took polyethylene glycol electrolyte powder, patients of group B took polyethylene glycol electrolytes powder combined with lactulose, and patients of group C took polyethylene glycol electrolytes powder combined with folium sennae. The colon cleaning quality, gastrointestinal complications, and patient compliance were evaluated.

RESULTS

The bowel preparation score of group B (7.96 ± 0.75, 94.3%) was better than those of groups A (5.11 ± 1.02, 66.7%) and C (5.83 ± 1.13, 22.2%), and the difference was statistically significant (P < 0.05). The rate of gastrointestinal complications in group B (2.7%, 8.3%) was much lower than that of group C (13.8%, 25%). No significant difference was observed in patient compliance between groups A (66.7%), B (63.8%) and C (55.6%).

CONCLUSION

Polyethylene glycol electrolyte powder combined with lactulose could improve the cleaning quality of bowel preparation in elderly patients with constipation and has no obvious gastrointestinal complications, representing a more effective and safer method for bowel preparation.

Identification of differential gene expression profile from peripheral blood cells of military pilots with hypertension by RNA sequencing analysis

Background

Elevated blood pressure is an important risk factor for cardiovascular disease and is also an important factor in global mortality. Military pilots are at high risk of cardiovascular disease because they undergo persistent noise, high mental tension, high altitude hypoxia, high acceleration and high calorie diet. Hypertension is the leading cause of cardiovascular disease in military pilots. In this study, we want to identify key genes from peripheral blood cells of military pilots with hypertension. Identification of these genes may help diagnose and control hypertension and extend flight career for military pilots.

Methods

We use RNA sequencing technology, bioinformatics analysis and Western blotting to identify key genes from peripheral blood cells of military pilots with hypertension.

Results

Our study detected 121 up-regulated genes and 623 down-regulated genes in the peripheral blood mononuclear cells (PBMCs) from hypertensive military pilots. We have also identified 8 important genes (NME4, PNPLA7, GGT5, PTGS2, IGF1R, NT5C2, ENTPD1 and PTEN), a number of gene ontology categories and biological pathways that may be associated with military pilot hypertension.

Conclusions

Our study may provide effective means for the prevention, diagnosis and treatment of hypertension for military pilot and extend their flight career.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0378-2) contains supplementary material, which is available to authorized users.

Glycosylated CD147 reduces myocardial collagen cross-linking in cardiac hypertrophy

The mechanism of transition from chronic pressure overload-induced cardiac hypertrophy to heart failure is still unclear. Angiotensin II (Ang II) may be an important factor that mediates the transition in the end-stage of cardiac hypertrophy. In the present study, Goldblatt two-kidney one-clip (2K1C) rat model was used to simulate Ang II-induced hypertension. The elevated Ang II not only induced the concentric hypertrophy of left ventricle and cardiac fibrosis, but also increased the expression and glycosylation of CD147 in 2K1C rats. The left ventricular structure and function detected by echocardiogram showed a sign of the transition from cardiac hypertrophy to heart failure in 16 weeks of 2K1C rats. Ang II can activate N-acetylglucosamine transferase V (GnT-V), a key enzyme for CD147 glycosylation. Retinoic acid, an agonist of GnT-V, further increased glycosylated CD147, and activated matrix metalloproteinase-2/-9 (MMP-2 and MMP-9) in the hypertrophied left ventricle of 2K1C rat. Meanwhile, collagen cross-linking in the hypertrophied left ventricle significantly reduced in 2K1C rats. On the contrary, tunicamycin, an inhibitor of N-glycan biosynthesis, inhibited glycosylation of CD147 and activity of MMP-2 and MMP-9, and then maintained a stable of collagen cross-linking in the 2K1C rat hearts. The above results suggested that Ang II increased glycosylated CD147 which activated MMP-2 and MMP-9. Collagens were degraded by the activated MMPs and then reduced collagen cross-linking. Finally, the hypertrophied left ventricle was progressively dilated in chronic pressure overload due to losing the limitation of collagen cross-linking. Therefore, the compensated hypertrophy of left ventricle gradually transited to congestive heart failure.

Simulated microgravity hampers Notch signaling in the fight against myocardial ischemia‑reperfusion injury

The gravitational field is an important determinant of cardiovascular function. Exposure to microgravity during spaceflight may lead to a series of maladaptive alterations in the cardiovascular system. The authors have previously demonstrated that microgravity can increase the susceptibility to myocardial ischemia‑reperfusion (IR) injury under simulated microgravity. Although Notch1 signaling protects against myocardial IR injury, whether Notch1 protects against myocardial IR injury under simulated weightlessness remains unknown. The present study is designed to investigate the role of the Notch1 receptor in myocardial IR injury under simulated weightlessness. The differences in Notch signaling expression and myocardial infarct size following myocardial IR were compared between normal rats and tail‑suspended rats that were kept in 30˚ head‑down tilt and hindlimb unloading position. The data revealed low expression levels of Notch1 receptor and its endogenous ligand Jagged1 in normal adult rat hearts. However, significantly higher expression of Notch1 was observed in the border zone compared with the infarcted area and the remote zone following myocardial IR. Notch1 expression was notably reduced in the infarcted hearts of tail‑suspended rats compared with the control group. Conversely, the myocardial infarct size was significantly increased in tail‑suspended rats compared with the control rats. In conclusion, these data suggested that the proper function of Notch signaling may be hampered under simulated microgravity.

Quality assessment of groundwater from the south-eastern Arabian Peninsula

Assessment of groundwater quality plays a significant role in the utilization of the scarce water resources globally and especially in arid regions. The increasing abstraction together with man-made contamination and seawater intrusion have strongly affected groundwater quality in the Arabia Peninsula, exemplified by the investigation given here from the United Arab Emirates, where the groundwater is seldom reviewed and assessed. In the aim of assessing current groundwater quality, we here present a comparison of chemical data linked to aquifers types. The results reveal that most of the investigated groundwater is not suitable for drinking, household, and agricultural purposes following the WHO permissible limits. Aquifer composition and climate have vital control on the water quality, with the carbonate aquifers contain the least potable water compared to the ophiolites and Quaternary clastics. Seawater intrusion along coastal regions has deteriorated the water quality and the phenomenon may become more intensive with future warming climate and rising sea level.

Simulated microgravity increases myocardial susceptibility to ischemia-reperfusion injury via a deficiency of AMP-activated protein kinase

Gravitation is an important factor in maintaining cardiac contractility. Our study investigated whether simulated microgravity increases myocardial susceptibility to ischemia-reperfusion (IR) injury. Using the Langendorff-perfused heart model with 300 beats/min pacing, 4-week tail suspension (SUS) and control (CON) male Sprague-Dawley rats (n = 10 rats/group) were subjected to 60 min of left anterior descending coronary artery (LAD) occlusion followed by 120 min of reperfusion. Left ventricular end-systolic pressure (LVESP), left ventricular end-diastolic pressure (LVEDP), creatine kinase (CK) and lactate dehydrogenase (LDH) activity, and infarct size were assessed. Data demonstrated that there were significantly increased LVEDP, CK, LDH, and infarct size in SUS compared with CON (P < 0.05), accompanied by decreased LVESP (P < 0.05). Furthermore, TUNEL-positive cardiomyocytes were higher in SUS than that in CON (P < 0.01), and AMP-activated protein kinase (AMPK) phosphorylation and Bcl-2/Bax in SUS were less compared with CON (P < 0.05). Similarly, isolated hearts pre-treated with A-769662 exhibited better recovery of cardiac function, increased AMPK phosphorylation, and reduced necrosis and apoptosis. Furthermore, AMPKα protein showed a significant suppression in 4-week hindlimb unweighting rats. These results suggest that AMPK deficiency increases myocardial susceptibility to IR injury in rats subjected to simulated microgravity.

ROS-Induced Nuclear Translocation of Calpain-2 Facilitates Cardiomyocyte Apoptosis in Tail-Suspended Rats

Isoproterenol (ISO) induced nuclear translocation of calpain-2 which further increased susceptibility of cardiomyocyte apoptosis in tail-suspended rats. The underlying mechanisms remain elusive. In the present study, the results showed that ISO (10 nM) significantly elevated NADPH oxidases (NOXs) activity and NOXs-derived ROS productions which induced nuclear translocation of calpain-2 in cardiomyocytes of tail-suspended rats. In contrast, the inhibition of NADPH oxidase or cleavage of ROS not only reduced ROS productions, but also resisted nuclear translocation of calpain-2 and decreased ISO-induced apoptosis of cardiomyocyte in tail-suspended rats. ISO also increased the constitutive binding between calpain-2 and Ca(2+)/calmodulin-dependent protein kinase II δB (CaMK II δB) in nuclei, concomitant with the promotion of CaMK II δB degradation and subsequent down-regulation of Bcl-2 mRNA expression and the ratio of Bcl-2 to Bax protein in tail-suspended rat cardiomyocytes. These effects of ISO on cardiomyocytes were abolished by a calpain inhibitor PD150606. Inhibition of calpain significantly reduced ISO-induced loss of the mitochondrial membrane potential, cytochrome c release into the cytoplasm, as well as the activation of caspase-3 and caspase-9 in mitochondrial apoptotic pathway. In summary, the above results suggest that ISO increased NOXs-derived ROS which activated nuclear translocation of calpain-2, subsequently nuclear calpain-2 degraded CaMK II δB which reduced the ratio of Bcl-2 to Bax, and finally the mitochondria apoptosis pathway was triggered in tail-suspended rat cardiomyocytes. Therefore, calpain-2 may represent a potentially therapeutic target for prevention of oxidative stress-associated cardiomyocyte apoptosis.

Nuclear Translocation of Calpain-2 Mediates Apoptosis of Hypertrophied Cardiomyocytes in Transverse Aortic Constriction Rat

Apoptosis of cardiomyocytes plays an important role in the transition from cardiac hypertrophy to heart failure. Hypertrophied cardiomyocytes show enhanced susceptibility to apoptosis. Therefore, the aim of this study was to determine the susceptibility to apoptosis and its mechanism in hypertrophied cardiomyocytes using a rat model of transverse abdominal aortic constriction (TAC). Sixteen weeks of TAC showed compensatory and pathological hypertrophy in the left ventricle. TUNEL-positive nuclei were significantly increased in TAC with angiotensin II (Ang II) treatment. Calpain inhibitor, PD150606, effectively inhibited Ang II-induced apoptosis of hypertrophied cardiomyocytes. Ang II increased nuclear translocation of intracellular Ca(2+) activated calpain-2 in hypertrophied cardiomyocytes. Ang II enhanced the interaction between activated calpain-2 and Ca(2+)/calmodulin-dependent protein kinase II δB (CaMKIIδB), and promoted the degradation of CaMKIIδB by calpain-2 in the nuclei of hypertrophied cardiomyocytes. Consequently, the depressed CaMKIIδB downregulated the expression of antiapoptotic Bcl-2 leading to mitochondrial depolarization and release of cytochrome c led to apoptosis of hypertrophied cardiomyocytes. In conclusion, hypertrophied cardiomyocytes show increased susceptibility to apoptosis during Ang II stimulation via nuclear calpain-2 and CaMKIIδB pathway.

[Dynamic assembly of intercalated disc during postnatal development in the rat myocardium]

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.

Natural radioactivity in groundwater from the south-eastern Arabian Peninsula and environmental implications

Groundwater is the most valuable resource in arid regions, and recognizing radiological criteria among other water quality parameters is essential for sustainable use. In the investigation presented here, gross-α and gross-β were measured in groundwater samples collected in the south-eastern Arabian Peninsula, 67 wells in Unite Arab Emirates (UAE), as well as two wells and one spring in Oman. The results show a wide gross-α and gross-β activities range in the groundwater samples that vary at 0.01∼19.5 Bq/l and 0.13∼6.6 Bq/l, respectively. The data show gross-β and gross-α values below the WHO permissible limits for drinking water in the majority of the investigated samples except those in region 4 (Jabel Hafit and surroundings). No correlation between groundwater pH and the gross-α and gross-β, while high temperatures probably enhance leaching of radionuclides from the aquifer body and thereby increase the radioactivity in the groundwater. This conclusion is also supported by the positive correlation between radioactivity and amount of total dissolved solid. Particular water purification technology and environmental impact assessments are essential for sustainable and secure use of the groundwater in regions that show radioactivity values far above the WHO permissible limit for drinking water.

[In vitro heart models simulating in vivo cardiac ischemia-reperfusion injury]

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.

Tetanic contraction induces enhancement of fatigability and sarcomeric damage in atrophic skeletal muscle and its underlying molecular mechanisms

Muscle unloading due to long-term exposure of weightlessness or simulated weightlessness causes atrophy, loss of functional capacity, impaired locomotor coordination, and decreased resistance to fatigue in the antigravity muscles of the lower limbs. Besides reducing astronauts' mobility in space and on returning to a gravity environment, the molecular mechanisms for the adaptation of skeletal muscle to unloading also play an important medical role in conditions such as disuse and paralysis. The tail-suspended rat model was used to simulate the effects of weightlessness on skeletal muscles and to induce muscle unloading in the rat hindlimb. Our series studies have shown that the maximum of twitch tension and the twitch duration decreased significantly in the atrophic soleus muscles, the maximal tension of high-frequency tetanic contraction was significantly reduced in 2-week unloaded soleus muscles, however, the fatigability of high-frequency tetanic contraction increased after one week of unloading. The maximal isometric tension of intermittent tetanic contraction at optimal stimulating frequency did not alter in 1- and 2-week unloaded soleus, but significantly decreased in 4-week unloaded soleus. The 1-week unloaded soleus, but not extensor digitorum longus (EDL), was more susceptible to fatigue during intermittent tetanic contraction than the synchronous controls. The changes in K+ channel characteristics may increase the fatigability during high-frequency tetanic contraction in atrophic soleus muscles. High fatigability of intermittent tetanic contraction may be involved in enhanced activity of sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) and switching from slow to fast isoform of myosin heavy chain, tropomyosin, troponin I and T subunit in atrophic soleus muscles. Unloaded soleus muscle also showed a decreased protein level of neuronal nitric oxide synthase (nNOS), and the reduction in nNOS-derived NO increased frequency of calcium sparks and elevated intracellular resting Ca2+ concentration ([Ca2+]i) in unloaded soleus muscles. High [Ca2+]i activated calpain-1 which induced a higher degradation of desmin. Desmin degradation may loose connections between adjacent myofibrils and further misaligned Z-disc during repeated tetanic contractions. Passive stretch in unloaded muscle could preserve the stability of sarcoplasmic reticulum Ca2+ release channels by means of keeping nNOS activity, and decrease the enhanced protein level and activity of calpain to control levels in unloaded soleus muscles. Therefore, passive stretch restored normal appearance of Z-disc and resisted in part atrophy of unloaded soleus muscles. The above results indicate that enhanced fatigability of high-frequency tetanic contraction is associated to the alteration in K+ channel characteristics, and elevated SERCA activity and slow to fast transition of myosin heavy chain (MHC) isoforms increases fatigability of intermittent tetanic contraction in atrophic soleus muscle. The sarcomeric damage induced by tetanic contraction can be retarded by stretch in atrophic soleus muscles.

Model simulation of inflow water to the Baltic Sea based on ¹²⁹I

The semi-enclosed Baltic Sea represents a vital economic and recreational resource for more than 90 million people inhabiting its coasts. Extensive contamination of this sea by a variety of anthropogenic pollutants has raised the concern of the people in the region. Quantifying seawater inflow is crucial for estimating potential environmental risks as well as to find the best remedial strategy. We present here a model to estimate water inflow from the North Sea to the Baltic Sea by utilizing ¹²⁹I as a tracer. The results predicted inflow range of 230-450 km³/y with best fit value around 330 km³/y from the North Sea to the Baltic Sea during 1980-1999. Despite limited time series data on ¹²⁹I, the model presented here demonstrates a new management tool for the Baltic Sea to calculate inflow water compared to conventional methods (such as salinity, temperature and hydrographic models).

[Autophagic flux of cardiomyocytes from 20-week transverse abdominal aortic constriction rats]

Cardiac autophagy dramatically increases in heart failure induced by sustained pressure overload. However, it has not yet been addressed if enhanced autophagy plays a role in protecting myocardium or mediating progression from compensative hypertrophy to heart failure. The aim of the present study was to detect autophagic flux of cardiomyocytes from 20-week transverse abdominal aortic constriction (TAC) rats. Fasting rats were used as the positive control for detecting cardiac autophagy. Echocardiography was applied to find the changes of cardiac structure and function. Immunofluorescent histochemistry and Western blot were used to analyze the related biomolecular indexes reflecting cardiac autophagic flux. After the previous methods for detecting cardiac autophagy were confirmed, the autophagic flux in cardiomyocytes of rats subjected to 20-week TAC was examined. The results showed that fasting had no obvious influence on parameters of cardiac structure in rats, including interventricular septal wall thickness and left ventricle posterior wall thickness, but heart rate, diastolic left ventricle internal dimension, fractional shortening of left ventricle dimension, ejection fraction and mitral inflow velocity decreased in rats after fasting for 3 d. Meanwhile, positively stained particles of LC3 and cathepsin D, but not ubiquitin and complement 9, distributed within cardiomyocytes of 3-day fasting rats, indicating augmented autophagic flux. Compared with sham rats, 20-week TAC rats did not show any changes of LC3, cathepsin D, ubiquitin and complement 9 in myocardium detected by immunofluorescent histochemistry. In addition, protein levels of LC3, cathepsin D and p62 in myocardium of TAC rats did not changed. These results reveal the unchanged autophagic flux in cardiomyocytes at middle or late phase of cardiac hypertrophy in TAC rats, implying a balance between inhibition of hypertrophy and activation of pressure load stress on autophagy.

[Four-week simulated weightlessness increases the expression of atrial natriuretic peptide in the myocardium]

One of the major circulatory changes that occur in human during space flight and simulated weightlessness is a cerebral redistribution of body fluids, which is accompanied by an increase of blood volume in the upper body. Therefore, atrial myocardium should increase the secretion of atrial natriuretic peptide (ANP), but the researches lack common conclusion until now. The present study was to investigate the expression level of ANP in simulated weightlessness rats, and to confirm the changes of ANP by observing the associated proteins of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). The tail-suspended rat model was used to simulate weightlessness. Western blots were carried out to examine the expression levels of ANP and SNARE proteins in atrial and left ventricular myocardium. The results showed that ANP expression in atrial myocardium showed an increase in 4-week tail-suspended rats (SUS) compared with that in the synchronous control rats (CON). We only detected a trace amount of ANP in the left ventricular myocardium of the CON, but found an enhanced expression of ANP in left ventricular myocardium of the SUS. Expression of VAMP-1/2 (vesicle associated SNARE) increased significantly in both atrial and left ventricular myocardium in the SUS compared with that in the CON. There was no difference of the expression of syntaxin-4 (target compartment associated SNARE) between the CON and SUS, but the expression of SNAP-23 showed an increase in atrial myocardium of the SUS compared with that in the CON. Synip and Munc-18c as regulators of SNAREs did not show significant difference between the CON and SUS. These results suggest that the expression of ANP shows an increase in atrial and left ventricular myocardium of 4-week tail-suspended rats. Enhanced expression of VAMP-1/2 associated with ANP vesicles confirms the increased expression of ANP in atrial and left ventricular myocardium.

[Depressed cardiac output at higher pacing rate in isolated working heart of rat]

OBJECTIVE

To observe the regulation of heart rate to cardiac pump function in the phase of negative force-frequency relationship and their possible mechanisms.

METHODS

The left ventricular pressure, aortic pressure, and cardiac output were measured in isolated working heart of rat from 240 to 300 beats/min of pacing rate.

RESULTS

Cardiac output of isolated working heart was decreased by a proximally 20% (P < 0.01) with the increase in the pacing rate from 240 to 300 beats/min. Left ventricular end-systolic pressure (LVESP) was declined by 4.8% (P < 0.05), but left ventricular end-diastolic pressure (LVEDP) was elevated by 139% (P < 0.01) with an increase in the pacing rate. Left atrium was enlarged at 300 beats/min of pacing rate. The time from peak to 75% relaxation in left ventricular pressure was shortened with the increased pacing rate. Pressure at aortic valve close was raised (P < 0.01) and ejection duration was shortened with the increased pacing rate (P < 0.01).

CONCLUSION

Those above results suggest that there are different mechanisms between the depressed cardiac output at higher heart rate and negative force-frequency relationship. The frequency-dependent acceleration of relaxation facilitates the decline of left ventricular pressure, and then may elevate the pressure of aortic valve close in the condition that the shape of aortic pressure curve stays the same. Therefore, the ejection duration is shortened at higher pacing rate. The shortened ejection duration may induce a decrease in stroke volume of the left ventricle. The increment of heart rate is not enough to compensate the decreased stroke volume. Finally, cardiac output shows a decrease at higher heart rate.

[Metabolites of long-time preserved-acutely isolated rat cardiomyocytes affect L-type Ca(2+) channel current]

The variability of peak current of L-type calcium channel (I(Ca,L)) shows an increase in cardiomyocytes after 6 h of preservation when the acutely isolated cardiomyocytes are preserved in a small volume buffer solution. The mechanism of the increased variability of I(Ca,L) is not clear. In order to obtain more accurately and stably experimental data of I(Ca,L), the aim of this study was to observe the pH changes of preservation buffer solution with acutely isolated rat cardiomyocytes, and the effects of pH changes on the shape of cardiomyocytes, the function of mitochondria and the gating property of L-type calcium channel. The results indicated that the pH was kept stable in 100 mL buffer solution, but was decreased from 7.20 to 6.95 in 20 mL buffer solution during 10 h of cardiomyocyte preservation. Therefore, 100 mL or 20 mL preservation solution was used as a normal control or acidotic group, respectively. The ratio of abnormal to normal rod-shaped cardiomyocytes increased in the acidotic group after 6 h of preservation. The acidosis induced a reduction in mitochondrial membrane potential indicated by JC-1 fluorescent probe after 8 h of cardiomyocyte preservation. The acidosis also shifted the autofluorescence of NADPH from blue to green after 8 h of cardiomyocyte preservation. The above changes in mitochondrial function induced a significant decrease in the peak I(Ca,L) and a shift in the clamped voltage at peak I(Ca,L) from +10 mV to 0 mV, after 10 h of cardiomyocyte preservation. These results suggest that the best way to preserve acutely isolated cardiomyocytes is to use a larger volume buffer system. In order to get stable peak I(Ca,L), we need to not only select a normal shape of cardiomyocyte at a bright field but also a blue fluorescent myocyte at an ultraviolet excitation.

Enhanced N-terminal degradation of troponin I blunts cardiac function responsiveness to isoproterenol in 4-week tail-suspended rats

The N-terminal extension of cardiac troponin I (cTnI) is important in regulating cardiac function. Although the normal rat myocardium shows some cTnI N-terminal degradation (cTnI-ND), exposure to 4 weeks of tail-suspension markedly increased cTnI-ND. We hypothesized that the increased cTnI-ND in tail-suspended rats may affect cardiac function, particularly during β-adrenergic (β-A) stimulation. The increase in cardiac output with isoproterenol (ISO) treatment was smaller in tail-suspended rats compared with controls. Left ventricular end-diastolic pressure was elevated and increases in maximal rates of left ventricular pressure development and relaxation were lower during ISO treatment in tail-suspended rats. Response to ISO, forskolin, DB-cAMP and IBMX was also lower in cardiomyocytes from tail-suspended rats. The increase in shortening and re-lengthening the rates of cardiomyocytes at a maximal dose of ISO, forskolin, DB-cAMP and IBMX treatment was limited in tail-suspended rats. There was no difference in Ca2+ sensitivity of the isometric force between tail-suspended and control rats, although Ca2+ sensitivity was decreased less in tail-suspended rats versus control rats during PKA phosphorylation. There was no difference in PKA protein expression and activation during ISO stimulation between the two groups. Due to the increase in cTnI-ND, ISO-induced phosphorylation of cTnI was reduced in tail-suspended rats. The total phospholamban expression and phosphorylation by ISO was unaltered in tail-suspended rat hearts. These data suggest that enhanced cTnI-ND following 4-week tail-suspension is a major component of the β-A receptor signaling pathway, depressing cardiac function under ISO stimulation.

Activation of BK(Ca) channels in zoledronic acid-induced apoptosis of MDA-MB-231 breast cancer cells

BACKGROUND

Zoledronic acid, one of the most potent nitrogen-containing biphosphonates, has been demonstrated to have direct anti-tumor and anti-metastatic properties in breast cancer in vitro and in vivo. In particular, tumor-cell apoptosis has been recognized to play an important role in the treatment of metastatic breast cancer with zoledronic acid. However, the precise mechanisms remain less clear. In the present study, we investigated the specific role of large conductance Ca(2+)-activated potassium (BK(Ca)) channel in zoledronic acid-induced apoptosis of estrogen receptor (ER)-negative MDA-MB-231 breast cancer cells.

METHODOLOGY/PRINCIPAL FINDINGS

The action of zoledronic acid on BK(Ca) channel was investigated by whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry, analysis of fragmented DNA by agarose gel electrophoresis, and flow cytometry assays. Cell proliferation was investigated by MTT test and immunocytochemistry. In addition, such findings were further confirmed with human embryonic kidney 293 (HEK293) cells which were transfected with functional BK(Ca) α-subunit (hSloα). Our results clearly indicated that zoledronic acid directly increased the activities of BK(Ca) channels, and then activation of BK(Ca) channel by zoledronic acid contributed to induce apoptosis in MDA-MB-231 cells. The possible mechanisms were associated with the elevated level of intracellular Ca(2+) and a concomitant depolarization of mitochondrial membrane potential (Δψm) in MDA-MB-231 cells.

CONCLUSIONS

Activation of BK(Ca) channel was here shown to be a novel molecular pathway involved in zoledronic acid-induced apoptosis of MDA-MB-231 cells in vitro.

Passive stretch reduces calpain activity through nitric oxide pathway in unloaded soleus muscles

Unloading in spaceflight or long-term bed rest induces to pronounced atrophy of anti-gravity skeletal muscles. Passive stretch partially resists unloading-induced atrophy of skeletal muscle, but the mechanism remains elusive. The aims of this study were to investigate the hypotheses that stretch tension might increase protein level of neuronal nitric oxide synthase (nNOS) in unloaded skeletal muscle, and then nNOS-derived NO alleviated atrophy of skeletal muscle by inhibiting calpain activity. The tail-suspended rats were used to unload rat hindlimbs for 2 weeks, at the same time, left soleus muscle was stretched by applying a plaster cast to fix the ankle at 35° dorsiflexion. Stretch partially resisted atrophy and inhibited the decreased protein level and activity of nNOS in unloaded soleus muscles. Unloading increased frequency of calcium sparks and elevated intracellular resting and caffeine-induced Ca(2+) concentration ([Ca(2+)]i) in unloaded soleus muscle fibers. Stretch reduced frequency of calcium sparks and restored intracellular resting and caffeine-induced Ca(2+) concentration to control levels in unloaded soleus muscle fibers. The increased protein level and activity of calpain as well as the higher degradation of desmin induced by unloading were inhibited by stretch in soleus muscles. In conclusion, these results suggest that stretch can preserve the stability of sarcoplasmic reticulum Ca(2+) release channels which prevents the elevated [Ca(2+)]i by means of keeping nNOS activity, and then the enhanced protein level and activity of calpain return to control levels in unloaded soleus muscles. Therefore, stretch can resist in part atrophy of unloaded soleus muscles.

Chronic coexistence of two troponin T isoforms in adult transgenic mouse cardiomyocytes decreased contractile kinetics and caused dilatative remodeling

Our previous in vivo and ex vivo studies suggested that coexistence of two or more troponin T (TnT) isoforms in adult cardiac muscle decreased cardiac function and efficiency (Huang QQ, Feng HZ, Liu J, Du J, Stull LB, Moravec CS, Huang X, Jin JP, Am J Physiol Cell Physiol 294: C213-C22, 2008; Feng HZ, Jin JP, Am J Physiol Heart Circ Physiol 299: H97-H105, 2010). Here we characterized Ca(2+)-regulated contractility of isolated adult cardiomyocytes from transgenic mice coexpressing a fast skeletal muscle TnT together with the endogenous cardiac TnT. Without the influence of extracellular matrix, coexistence of the two TnT isoforms resulted in lower shortening amplitude, slower shortening and relengthening velocities, and longer relengthening time. The level of resting cytosolic Ca(2+) was unchanged, but the peak Ca(2+) transient was lowered and the durations of Ca(2+) rising and decaying were longer in the transgenic mouse cardiomyocytes vs. the wild-type controls. Isoproterenol treatment diminished the differences in shortening amplitude and shortening and relengthening velocities, whereas the prolonged durations of relengthening and Ca(2+) transient in the transgenic cardiomyocytes remained. At rigor state, a result from depletion of Ca(2+), resting sarcomere length of the transgenic cardiomyocytes became shorter than that in wild-type cells. Inhibition of myosin motor diminished this effect of TnT function on cross bridges. The length but not width of transgenic cardiomyocytes was significantly increased compared with the wild-type controls, corresponding to longitudinal addition of sarcomeres and dilatative remodeling at the cellular level. These dominantly negative effects of normal fast TnT demonstrated that chronic coexistence of functionally distinct variants of TnT in adult cardiomyocytes reduces contractile performance with pathological consequences.

[Remodeling of cardiac gap junctions and arrhythmias]

In the heart, gap junctions mediate electrical and chemical coupling between adjacent cardiomyocytes, forming the cell-to-cell pathways for orderly spread of the wave of electrical excitation responsible for a functional syncytium. Three principal connexins are expressed in cardiomyocytes, connexin 43 (CX43), CX40, and CX45. CX43 predominates in ventricular muscle cells. Most of the gap junctions, assembled from CX43, are located at the intercalated discs, often with larger junctional plaques at the disc periphery. The gap junctions are rarely distributed to the sides of the cardiomyocyte. The ischemia-reperfusion, cardiac hypertrophy, heart failure, hypercholesterolemia, and diabetes mellitus induce gap junction remodeling. The gap junction remodeling induced by above-mentioned diseases shows similar characteristics, including down-regulation of CX43, reduction in gap junction plaque size, increased heterogeneity and lateralization of gap junction distribution, and dephosphorylation of CX43. The elevated angiotensin II concentration in local myocardium may play an important role in the gap junction remodeling. The down-regulation of CX43 and lateralization of gap junction distribution alter anisotropic spread of the impulse of ventricular myocardium. The dephosphorylation of CX43 not only reduces electrical conductance, but also decreases permeability of chemicals between cardiomyocytes. The lateralization of gap junctions may increase the number of hemichannels formed by CX43. The opening of hemichannels induces ATP efflux and Na(+) influx, which forms a delayed after-depolarization. The gap junction remodeling in pathological condition produces arrhythmia substrate in the ventricles. In this review, the current knowledge on the relationship between the remodeling of cardiac gap junctions and arrhythmias were summarized.

[The influence of contraction modes on the phosphorylation of p38/Akt]

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Birth weight and subsequent risk of obesity: a systematic review and meta-analysis

This report describes the association between birth weight (BW) and obesity. Screening of 478 citations from five electronic databases resulted in the inclusion of 33 studies, most of medium quality. The meta-analysis included 20 of these published studies. The 13 remaining articles did not provide sufficient dichotomous data and were systematically reviewed, revealing results consistent with the meta-analysis. Our results revealed that high BW (>4000 g) was associated with increased risk of obesity (odds ratio [OR], 2.07; 95% confidence interval [CI], 1.91-2.24) compared with subjects with BW ≤ 4000 g. Low BW (<2500 g) was associated with decreased risk of obesity (OR, 0.61; 95% CI, 0.46-0.80) compared with subjects with BW ≥ 2500 g. However, when two studies exhibited selection bias were removed, the results indicated no significant association between low BW and obesity (OR, 0.77; 95% CI, 0.58-1.04). Sensitivity analyses showed that differences in the study design, sample size and quality grade of the study had an effect on the low BW/obesity association, which low BW was not associated with the risk of obesity in cohort studies, studies with large sample sizes and studies with high quality grades. Pooled results were similar when normal birth weight (2500-4000 g) was used as the reference category. Subgroup analyses based on different growth and developmental stages (pre-school children, school children and adolescents) also revealed that high BW was associated with increased risk of obesity from childhood to early adulthood. No significant evidence of publication bias was present. These results suggest that high BW is associated with increased risk of obesity and may serve as a mediator between prenatal influences and later disease risk.

[Cardioprotection by the inhibitory effect of nitric oxide]

Endothelial and neuronal nitric oxide synthases (eNOS and nNOS) are constitutively expressed in cardiomyocytes under the physiological condition, while inducible nitric oxide synthase (iNOS) is only expressed in cell stress. Nitric oxide (NO) derived from the constitutive isoforms of eNOS and nNOS plays four kinds of inhibitory effects on the myocardium: reducing the contractile frequency of cardiomyocyte, slightly attenuating cardiac contractility, accelerating relaxation and increasing distensibility of cardiomyocyte, and slightly inhibiting mitochondrial respiration and improving the efficiency of myocardial oxygen consumption. In conditions of enhanced cardiac reserve and cardiac hypertrophy, NO derived from eNOS, which forms a complex with a certain kind of receptor on the sarcolemma, modulates receptor-mediated signaling and generates an "accentuated antagonism" by moderate inhibition of cardiac contractility. NO derived from the complex of nNOS-ryanodine receptor (RyR) stabilizes RyR calcium release and increases the efficiency of Ca(2+) cycling in sarcoplasmic reticulum by the inhibitory effects. However, besides the above-mentioned inhibitions of NO derived from eNOS and nNOS, NO derived from iNOS generally prevents mitochondrial permeability transition pore opening by inhibiting mitochondrial respiration under the conditions of the myocardial ischemia-reperfusion injury and heart failure. Therefore, both in the physiological condition and in the pathological condition, NO exhibits a moderate inhibition in cardiac function, and eventually produces cardioprotection.

High glucose alters apoptosis and proliferation in HEK293 cells by inhibition of cloned BK Ca channel

It has been reported that diabetic vascular dysfunction is associated with impaired function of large conductance Ca(2+) -activated K(+) (BK(Ca) ) channels. However, it is unclear whether impaired BK(Ca) channel directly participates in regulating diabetic vascular remodeling by altering cell growth in response to hyperglycemia. In the present study, we investigated the specific role of BK(Ca) channel in controlling apoptosis and proliferation under high glucose concentration (25 mM). The cDNA encoding the α+β1 subunit of BK(Ca) channel, hSloα+β1, was transiently transfected into human embryonic kidney 293 (HEK293) cells. Cloned BK(Ca) currents were recorded by both whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry and analysis of fragmented DNA by agarose gel electrophoresis. Cell proliferation was investigated by flow cytometry assays, MTT test, and immunocytochemistry. In addition, the expression of anti-apoptotic protein Bcl-2, intracellular Ca(2+) , and mitochondrial membrane potential (Δψm) were also examined to investigate the possible mechanisms. Our results indicate that inhibition of cloned BK(Ca) channels might be responsible for hyperglycemia-altered apoptosis and proliferation in HEK-hSloα+β1 cells. However, activation of BK(Ca) channel by NS1619 or Tamoxifen significantly induced apoptosis and suppressed proliferation in HEK-hSloα+β1 cells under hyperglycemia condition. When rat cerebral smooth muscle cells were cultured in hyperglycemia, similar findings were observed. Moreover, the possible mechanisms underlying the activation of BK(Ca) channel were associated with decreased expression of Bcl-2, elevation of intracellular Ca(2+) , and a concomitant depolarization of Δψm in HEK-hSloα+β1 cells. In conclusion, cloned BK(Ca) channel directly regulated apoptosis and proliferation of HEK293 cell under hyperglycemia condition.

Evidence that apoptotic signalling in hypertrophic cardiomyocytes is determined by mitochondrial pathways involving protein kinase Cδ

1. Cardiomyocyte apoptosis plays an important role in the transition from cardiac hypertrophy to heart failure. Hyper-trophic cardiomyocytes show an increased susceptibility to apoptotic stimuli, but the mechanisms remain unclear. 2. We hypothesized that activated protein kinase Cδ (PKCδ) associated with cardiomyocyte hypertrophy could move from the cytoplasm to mitochondria, and subsequently trigger the apoptotic signalling pathway. 3. Hypertrophy was induced in cultured neonatal rat cardiomyocytes using endothelin-1 (ET-1), insulin-like growth factor-1 (IGF-1), thyroid hormone (T(3) ) or angiotensin-II (AngII). AngII at high concentrations (1 and 10 nmol/L) also induced apoptosis. Hypertrophic cells were then treated with AngII with or without specific inhibitors of the angiotensin receptors AT(1) and AT(2) (losartan and PD123319, respectively), endothelin receptor A (BQ-123) and PKCδ (rottlerin). ET-1 plus AngII had a threefold and significant increase in apoptosis in the hypertrophic cultures compared with AngII alone. In association with the increase in apoptosis, this treatment also promoted mitochondrial translocation of PKCδ, and increased expression of cleaved caspase 9 and activity of caspase 3. All of these increases were modulated by concurrent use of the PKCδ inhibitor, rottlerin. 4. The results suggest that apoptotic signalling in hypertrophic cardiomyocytes is determined by mitochondrial pathways involving PKCδ.

[Morphological signs of survival cultured adult rat cardiomyocytes]

OBJECTIVE

To clarify the key morphological signs for the survival of adult rat cardiomyocytes in primary culture.

METHODS

The adult rat hearts were retrogradely superfused by Langendorff apparatus. Cardiomyocytes were digested by collagenase I and cultured in three groups: (1) Serum free medium + BA (Bongkrekic acid, apoptotic inhibitor), (2) 5% serum medium, and (3) 5% serum medium + BA. The morphological alterations were observed and the percentage of rod-shaped cardiomyocytes, the apoptotic rate of cells, the rate of pseudopodium formation and the nuclear distances of cardiomyocytes were detected during culture.

RESULTS

(1) The percentage of rod-shaped cardiomyocytes decreased gradually in the first 3 days of cell culture. The percentage of rod-shaped cardiomyocytes cultured without fetal bovine serum (FBS) decreased more rapidly than those cultured with FBS. No differences were noticed between with and without the addition of apoptotic inhibitor BA. The apoptotic rate of cardiomyocytes increased in the first 3 days of cell culture, and the apoptotic rate of cells cultured without FBS increased more than that cultured with FBS. Also BA had no effect on apoptotic rate. (2) Cardiomyocytes cultured with FBS spread from the intercalated disk and extended pseudopodium on the second or third day of cell culture. Cardiomyocytes with thin membranous pseudopodium developed would survive and spread laterally at the 6th day of culture. Cells with the elongated morphology gradually spread extensively and took on a spheroidal shape. Myofibrils gradually lost their parallel. Cells cultured without FBS had no pseudopodium formation. The intercalated disk of cells gradually changed blunt. There was no effect on the rate of pseudopodium formation when added with apoptotic inhibitor BA. (3) Cytoskeletal remodeling occurred in survived cardiomyocytes. After 6 days of culture, cardiomyocytes exhibited characteristic of redifferentiation. (4) The distance between nuclei decreased in a single cardiomyocyte cultured with FBS for the cytoskeletal reconstruction, whereas it remained unchanged in cardiomyocytes cultured without FBS.

CONCLUSION

We clarify the pseudopodium developed on the second or third day of cell culture will be the critical morphological signs of survival cultured adult rat cardiomyocytes. It is necessary to add FBS for the formation of pseudopodium.

[Cardiac hypertrophy and changes in contractile function of cardiomyocyte]

To investigate the cellular mechanisms of pressure-overload cardiac hypertrophy transition to heart failure, we observed time course of changes in morphology and contractile function of cardiomyocytes in transverse abdominal aortic constriction (TAC) rats. Since TAC rats suffered higher stress, body weight had a slower growth rate compared with that of synchronous control rats. Therefore, the left ventricular to body weight ratio produced experimental bias to evaluate the degree of cardiac hypertrophy. Length and width of collagenase-isolated cardiomyocyte were directly measured. Length, width and calculated surface area of cardiomyocyte showed a progressive increase in 8-, 16-, and 20-week TAC rats. The increasing rate of surface area in cardiomyocytes was higher at the middle stage of TAC (from the eighth to sixteenth week). Due to the constraint of fibrosis formation, the increasing rate of surface area in cardiomyocytes was slower at the late stage of TAC (from the sixteenth to twentieth week). The sarcomere length of cardiomyocytes was unchanged, whereas sarcomere numbers were significantly increased in 8-, 16-, and 20-week TAC rats. Shortening amplitude of unloaded contraction in single cardiomyocyte was significantly enhanced in 1-week TAC rats, but not altered in 8-week TAC rats compared with that in the synchronous control rats. On the contrary, unloaded shortening amplitude of single cardiomyocyte was significantly reduced in 16- and 20-week TAC rats. The above results suggest that the reduced shortening amplitude may be associated with intrinsic molecular alterations in hypertrophied cardiomyocytes.

[Calpain mediates cardiac troponin I degradation in tail-suspended rats]

The aim of the present study was to investigate the expressions of calpain and calpastatin in the myocardium of simulated weightlessness rats, and to elucidate the underlying mechanism of cardiac troponin I (cTnI) degradations. Tail-suspended (SUS) rats were used as a simulated weightlessness model on the ground. The myocardium of rats was homogenized, and the expressions of calpain-1, calpain-2, calpastatin and cTnI were analyzed by Western blotting technique. Calpastatin expression was significantly decreased in 2- and 4-week SUS groups compared with that in the synchronous controls (P<0.05). Calpain-2 expression was slightly decreased, whereas calpain-1 expression was unaltered in SUS groups. However, calpain-1/calpastatin and calpain-2/calpastatin ratios were increased after tail-suspension, being significantly higher in 2- and 4-week SUS groups than those in the synchronous controls (P<0.05, P<0.01). Cardiac TnI degradation was significantly increased after tail-suspension (P<0.01), but cTnI degradation in both SUS and control groups was significantly inhibited by a non-specific inhibitor of calpain, PD150606 (P<0.01). These results suggest that an increase in calpain activity may enhance cTnI degradation in the myocardium of tail-suspended rats.

Intelligence in relation to obesity: a systematic review and meta-analysis

We performed a systematic review describing obesity/intelligent quotient (IQ) association, particularly childhood IQ in relation to adulthood obesity. After screening 883 citations from five electronic databases, we included 26 studies, most of medium quality. The weighted mean difference (WMD) of the full IQ (FIQ)/obesity association in the pre-school children was -15.1 (P > 0.05). Compared with controls, the WMD of FIQ and performance IQ of obese children were -2.8 and -10.0, respectively (P < 0.05), and the WMD of verbal IQ was -7.01 (P > 0.05). With increasing obesity, the FIQ in pre-school children declined, with a significant difference for severely obese children and FIQ. In pubertal children, a slightly different effect of FIQ and obesity emerged. Two studies reported an inverse FIQ/obesity association in adults, but it was non-significant after adjusting for educational attainment. Four papers found that childhood FIQ was inversely associated with adult body mass index, but after adjusting for education, became null. Overall there was an inverse FIQ/obesity association, except in pre-school children. However, after adjusting for educational attainment, FIQ/obesity association was not significantly different. A lower FIQ in childhood was associated with obesity in later adulthood perhaps with educational level mediating the persistence of obesity in later life.

Activation of BKCa channel is associated with increased apoptosis of cerebrovascular smooth muscle cells in simulated microgravity rats

Cerebral arterial remodeling is one of the critical factors in the occurrence of postspaceflight orthostatic intolerance. We hypothesize that large-conductance calcium-activated K+ (BKCa) channels in vascular smooth muscle cells (VSMCs) may play an important role in regulating cerebrovascular adaptation during microgravity exposure. The aim of this work was to investigate whether activation of BKCa channels is involved in regulation of apoptotic remodeling of cerebral arteries in simulated microgravity rats. In animal studies, Sprague-Dawley rats were subjected to 1-wk hindlimb unweighting to simulate microgravity. Alterations of BKCa channels in cerebral VSMCs were investigated by patch clamp and Western blotting; apoptosis was assessed by electron microscopy and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick-end labeling (TUNEL). To evaluate the correlation of BKCa channel and apoptosis, channel protein and cell nucleus were double-stained. In cell studies, hSloα+β1 channel was coexpressed into human embryonic kidney 293 (HEK293) cells to observe the effects of BKCa channels on apoptosis. In rats, enhanced activities and expression of BKCa channels were found to be correlated with increased apoptosis in cerebral VSMCs after simulated microgravity. In transfected HEK293 cells, activation of cloned BKCa channel induced apoptosis, whereas inhibition of cloned BKCa channel decreased apoptosis. In conclusion, activation of BKCa channels is associated with increased apoptosis in cerebral VSMCs of simulated microgravity rats.

Excessive thyroxine enhances susceptibility to apoptosis and decreases contractility of cardiomyocytes

Excessive thyroid hormone induces cardiac hypertrophy and promotes heart failure in patients with hyperthyroidism, but the mechanism remains elusive. Rats were orally administered with levothyroxine (100 microg/kg, T(4)) for 4 weeks to induce hyperthyroidism. The calculated stroke volume decreased and the shortening amplitude-frequency relationship in unloaded contraction of isolated cardiomyocytes was negative in T(4)-treated rats. Apoptotic rates increased and DNA laddering was also detectable in T(4)-treated rat hearts. By contrast, in primary cultured cardiomyocytes, T(3) induced dose-dependent hypertrophy but did not affect the apoptotic rate. Angiotensin II further increased the apoptotic rate of T(3)-induced hypertrophied cardiomyocytes. The apoptotic rate was dependent on the extent of cardiomyocyte hypertrophy. These results suggest that cardiac contractility is enhanced during the early stage of hyperthyroidism, but decreased during the late stage of hyperthyroidism. The hypertrophied cardiomyocytes were also susceptible to apoptotic stimulation by angiotensin II. Depressed cardiac contractility and enhanced apoptosis may lead to heart failure in hypertrophied myocardium.