[Spatiotemporal evolution of COVID-19 epidemic in the early phase in China].

Objective: Based on the geographic information systems, we exploreed the spatiotemporal clustering and the development and evolution of COVID-19 epidemic at prefectural level in China from the time when the epidemic was discovered to the time when the lockdown ended in Wuhan. Methods: The information and data of the confirmed COVID-19 cases from December 8, 2019 to April 8, 2020 were collected from 367 prefectures in China for a spatial autocorrelation analysis with software GeoDa, and software ArcGIS was used to visualize the results. Software SatScan was used for spatiotemporal scanning analysis to visualize the hot-spot areas of the epidemic. Results: The incidence of new cases of COVID-19 had obvious global autocorrelation and the partial autocorrelation results showed that incidence of COVID-19 had different spatial distribution at different times from December 8, 2019 to March 4, 2020. There was no significant difference in global autocorrelation coefficient from March 5, 2020 to April 8, 2020. The statistical analysis of spatiotemporal scanning identified two kinds of spatiotemporal clustering areas, the first class clustering areas included 10 prefectures, mainly distributed in Hubei, from January 13 to February 25, 2020. The secondary class clustering areas included 142 prefectures, mainly distributed in provinces in the north and east of Hubei, from January 23 to February 1, 2020. Conclusions: There was a clear spatiotemporal correlation in the distribution of the outbreaks in the early phase of COVID-19 epidemic (December 8, 2019-March 4, 2020) in China. With the decrease of the case and effective prevention and control measures, the epidemics had no longer significant correlations among areas from March 5 to April 8. The study results showed relationship with time points of start and adjustment of emergency response at different degree in provinces. Furthermore, improving the early detection of new outbreaks and taking timely and effective prevention and control measures played an important role in blocking the transmission.

[Research progresses in the cytoskeleton and its functions in osteoblasts].

Osteoblasts are cells that are in charge of bone formation and play an important role in bone remodeling. Cytoskeleton is widely found in eukaryotic cells, and not only plays an important role in maintaining the order of cell morphology and internal structure, but also may be involved in mechanotransduction, the regulation of cell differentiation, proliferation, apoptosis, migration and the expression of related genes. The studies on the function of the cytoskeleton in osteoblasts may provide new ideas for dental fields in such aspects as guided bone regeneration, orthodontic tooth movement, distraction osteogenesis and postoperative bone healing. This article reviewed the research progresses about cytoskeleton in osteoblasts.

[Influence of myocardial ischemia/reperfusion in vitro on nuclear envelope NTPase activity and mRNA export in the cardiomyocyte of rabbits].

AIM: To study the alteration of nuclear envelope associated NTPase activity and mRNA nucleocytoplasmic transport in rabbit cardiomyocyte following in vitro ischemia and reperfusion. METHODS: The model of myocardial perfusion in rabbit was used to produce myocardial I/R injury and cardiomyocyte nuclear envelope vesicles were prepared by density gradient centrifugation for the assay of mRNA transport rate and NTPase activity. RESULTS: NTPase activity was reduced and mRNA transport rate was significantly decreased in I/R (P < 0.01) but not in ischemia group( P > 0.05). CONCLUSION: The nuclear envelope vesicles had been injured following ischemia and reperfusion and resulted in NTPase activity reduced and egress of mRNA interrupted, and therefore may lead to decreasing of protein synthesis.

Effect of batroxobin against dog heart ischemia/reperfusion injury.

AIM: To study the effect of batroxobin(Bat) on dog heart ischemia/reperfusion (I/R) injury. METHODS: Dog heart I/R injury was induced by occluding the left anterior descending coronary artery for 30 min and restoring blood perfusion for 90 min. Bat was intravenously injected before heart ischemia and 15 min before reperfusion. Plasma creatine kinase (CK), lactate dehydrogenase (LDH), and myocardial malondiaedehyde (MDA) concentrations were measured. The pathologic changes of I/R myocardium were observed. RESULTS: Bat reduced the mortality rate of I/R dog (I/R group 65.0% vs Bat-I group 30.0% and Bat-II group 28.6%, P < 0.05). Myocytes of I/R heart showed intracellular edema, damaged mitochondria, and concentrated nucleus. Bat decreased these changes. In Bat-I and Bat-II group, plasma CK and LDH level were reduced, the +dp/dtmax and -dp/dtmax at 30 min after ischemia and 90 min after reperfusion were elevated, and left ventricular end dilation pressure (LVEDP) was lowered. The myocardial MDA contents were decreased by 42.3% and 38.1% (P < 0.01) in Bat-I and Bat-II group, respectively. CONCLUSION: Bat may exert an apparent role against dog heart ischemia/reperfusion injury and improve myocardial function.

[Inhibition of ERK1/2 activity and c-fos mRNA after coronary artery balloon injury by intracoronary radiation in swine].

The effect of intracoronary radiation on extracellular signal regulated kinase 1/2 (ERK1/2) activity and c-fos mRNA after coronary artery balloon injury was investigated in swine. Twenty three swines were randomly divided into a radiation group and a control group after coronary balloon over stretch. The dilated segments in the radiation group were exposed to a dose of 20 Gy by a catheter based radiation system. The animals were sacrificed at 3 (6 swines from each group) and 30 days (6 swines from radiation group and 5 from control group) after the operation. The injured segments were processed to examine c-fos gene expression by reverse transcription polymerase chain reaction (RT PCR) and to measure the activity of ERK1/2 biochemically. Intracoronary radiation decreased significantly the ERK1/2 activity and gene expression of c-fos in the radiation treated animals 3 days after coronary balloon injury (20.5%,P<0.01; 47.7%,P<0.05), but neither ERK1/2 activity nor c-fos gene expression was significantly affected by endovascular radiation in animals 30 days after balloon injury. Therefore, both ERK1/2 and c-fos may be involved in inhibiting restenosis.

[The changes in the heart and erythrocyte L-arginine transport of spontaneously hypertensive rats].

Changes of L-arginine/nitric oxide pathway in heart and of L arginine transport in erythrocytes and their relationship were investigated in spontaneously hypertensive rats (SHR). 12 and 16 weeks old SHR, 16 weeks old SHR with captopril treatment for 4 weeks and 16 weeks old Wistar-Kyoto (WKY) rats were used. L arginine transport of myocardial ventricular tissue and erythrocytes, total nitric oxide synthase (tNOS) activity, nitrite and nitrate (NO(2) + NO(3)) and cyclic GMP (cGMP) content in myocardium were measured. The result showed that in myocardial ventricular tissue of SHR L-arginine transport decreased significantly with V(max) of the high-affinity transport being decreased by 24.3% (P<0.05, 12W group), 36.4% (P<0.01, 16W group) as compared with WKY group. Michaelis constant (K(m)) of low affinity transport was significantly lower than that of WKY group. NO(2) + NO(3) and cGMP content were respectively decreased by 24.6%, 19.8% (P>0.05, P<0.05, 12W group), 52.5%, 60.4% (P<0.05, P<0.01, 16W group) and 14.8%, 23% (P>0.05, P<0.05, SHR+C group) as compared with WKY group. But the K(m) of L-arginine high-affinity transport and the V(max) of low affinity transport and tNOS activity were not significantly changed. In erythrocytes, the changes of L-arginine transport coincided with those of myocardial tissue. The V(max) had significant positive correlation with the V(max) of high-affinity transport in myocardial tissue, r=0.5606, P=0.01 and had negative correlation with left ventricular weight to body weight radio, r=0.6231,P<0.01. These results indicate that the activity of L-arginine/nitric oxide pathway inhibited in myocardial tissue of SHR. The correlation between the inhibitory degree of L-arginine/nitric oxide pathway and the degree of ventricular hypertrophy is negative. The changes of L-arginine transport in erythrocytes coincide with those in myocardium.

[Plasmid pcDNA3 enhances Ca(2+) transport of sarcoplasmic reticulum in ischemic skeletal muscle of rats].

The effects of plasmid pcDNA3 on Ca(2+) transport of sarcoplasmic reticulum (SR) in ischemic skeletal muscle was investigated. The results show that Ca(2+) transport (including Ca(2+) uptake and Ca(2+) release) rate of SR in ischemic skeletal muscle was markedly increased compared with that in non-ischemic muscle (P<0.01 or P<0.05). After plasmid pcDNA3 bound to the DNA binding proteins of SR, Ca(2+) transport of SR was further increased. The results suggest that the effect of plasmid DNA on the ability of Ca(2+) transport in SR of ischemic skeletal muscle is the same as is observed in normal skeletal muscle. The pathophysiological significance of the present finding deserves further exploration.

Basic fibroblast growth factor increases nitric oxide and endothelin production in rat aorta.

The study was undertaken to investigate the effect of basic fibroblast growth factor (bFGF) on aortic production of nitric oxide (NO) and endothelin of aorta in spontaneously hypertensive rats (SHR) and WKY rats. Rat aortas were cut into vessel slices and incubated with 10 or 100 ng/ml bFGF for 6 hours. Nitric oxide synthase (NOS) activity in aortic slices and contents of NO(-)(2) and endothelin in the medium were determined. The results showed that NOS activity in aortic slices of SHR was 17.6% lower than that of WKY (P<0.01). NO(-)(2) and endothelin contents in the medium of SHR aortic slices were 59.7% lower and 37.4% higher than those of WKY aortic slices. Upon the exposure of low and high doses of bFGF, NOS activity in the aorta of SHR was increased by 29.7% and 59.6% (both P<0.01),respectively, while the NO(-)(2) contents in the medium were increased respectively by 28.2% (P<0.05) and 70.5% (P<0.01). Aortic endothelin production was increased by 24.1% and 44.5% (both P<0.01) respectively while the NOS activity in the aorta of WKY was increased by 24.4% and 53.7% (both P<0.01). NO(-)(2) contents in the medium were augmented by 18.8% (P<0.05)and 25.9% (P<0.01), respectively. Aortic endothelin production was increased by 84.1% and 93.1% (both P<0.01). It is concluded that bFGF may modulate the production of NO and endothelin in both SHR and WKY rats.

[Involvement of calcineurin-dependent signal pathway in the angiotensin II-induced cardiac myocyte hypertrophy].

The present study was undertaken to observe the role of calcineurin (CaN)-dependent signaling pathway in the angiotensin II (Ang II)-induced cardiac myocyte hypertrophy. In cultured myocardial cells of neonatal rats, Ang II was used to stimulate hypertrophy and CaN-pathway blocked by CsA(an inhibitor of CaN). 3H-leucine incorporation, and activities of CaN, mitogen-activated protein kinase (MAPK) and protein kinase C (PKC) were investigated. The results showed that 3H-leucine incorporation of Ang II-stimulated myocardial cells was 46% higher than control (P < 0.01), which could be inhibited by CsA (0.5-5 micrograms/ml) and PD098059(an inhibitor of MAPK). CaN and PKC activities of Ang II-stimulated myocardial cells were 39% and 280% higher than control (P < 0.001) respectively, while no significant increase in MAPK activities was observed. CsA could reverse the increase of CaN activity, but had no effect on PKC. It is concluded that the CaN-dependent signaling pathway may play an important role in the development of the Ang II-induced cardiac myocyte hypertrophy.

[Alteration of ryanodine receptors in cardiac sarcoplasmic reticulum and nuclear envelope of rats during sepsis].

To investigate changes of ryanodine receptors in the sarcoplasmic reticulum (SR) and the nuclear envelope (NE) of rat cardiac myocytes during sepsis induced by cecal ligation and puncture (CLP), myocardial SR and NE were fractionated with density gradient centrifugation and the characteristic of ryanodine receptor was assayed with a method of radioreceptor binding assay. The result showed that Bmax of ryanodine receptors in cardiac SR was increased by 23% during early sepsis (9 h after CLP), but decreased by 38% during late sepsis (18 h after CLP). Bmax of ryanodine receptors in cardiac NE, on the other hand, was increased by 100% and 160% during early and late sepsis respectively. Kd of ryanodine binding to SR and NE remained unchanged during sepsis. These results demonstrated up-regulation of ryanodine receptors in SR occurred during early sepsis and down-regulation of these receptors in SR occurred during late sepsis, while up-regulation of ryanodine receptors in NE occurred during both the early and the late sepsis.

Role of endogenous carbon monoxide in the pathogenesis of hypotension during septic shock.

A sepsis model induced by cecal ligation and puncture was used to study the role of endogenous carbon monoxide in hypotension pathogenesis of rats during septic shock. After administration of zinc deuteroporphyrin 2,4-bisglycol (ZnDPBG),an inhibitor of heme oxygenase (HO),blood pressure (BP),HO activity and carbon monoxide (CO) release from vascular muscle tissue were measured. The results showed that BP of sepsis rats, including systolic and diastolic arterial BP, decreased significantly while HO activity and CO content were significantly increased. In contrast, after administration of ZnDPBG, BP of sepsis rats was significantly increased while the HO activity and CO production were significantly decreased. These findings suggest that HO activity and CO release within vascular musculature are increased during septic shock; inhibition of HO may elevate BP of rats during septic shock through a decrease of endogenous CO production. It is concluded that endogenous CO derived from vascular muscle cells plays an important role in regulating vascular tone, and the up-regulation of HO activity followed by subsequent CO production contributes to hypotension pathogenesis during septic shock.

[Inhibition of signal transduction pathways of endothelin-1-induced proliferation of vascular smooth muscle cells by nitric oxide].

The signal transduction pathways of the inhibitory effect of nitric oxide (NO) on endothelin (ET)-induced proliferation of vascular smooth muscle cells (VSMCs) were studied. 3H-thymidine (TdR) incorporation, mitogen-activated protein kinase (MAPK) activity and protein kinase C (PKC) activity of cultured VSMCs of rabbits thoracic aorta were measured in the presence of either NO precursor L-arginine (L-Arg) or NO donor 3-morpholino sydnonimine-hydrochloride (SIN-1), or ET-1 alone or with L-Arg or SIN-1. The results show: (1) ET-1 (10(-8) mol/L) significantly increased VSMCs 3H-TdR incorporation (5 times, P < 0.01), MAPK activity (4 times, P < 0.01) and PKC activity (3 times, P < 0.01), as compared with control. L-Arg or SIN-1 alone was without effect on 3H-TdR incorporation, MAPK activity and PKC activity. (2) When ET-1 and L-Arg (2, 5, 10 mmol/L) were simultaneously administered, 3H-TdR incorporation and activity of both MAPK and PKC were all significantly decreased in comparison with the ET group. (3) When ET-1 + SIN-1 (5, 10, 50 mumol/L), the effects coincide with those of the ET-1 + L-Arg groups. These findings indicate that NO inhibition of the signal transduction pathways of the ET-1-induced proliferation of VSMCs may be mediated by the inhibition of ET-1-induced activation of both PKC and MAPK.

Role of endogenous carbon monoxide in hypertension pathogenesis of rats.

The present study investigated the contribution of endogenous heme oxygenase (HO)/carbon monoxide (CO) system to hypertension pathogenesis of rats. Zinc deuteroporphyrin 2,4-bisglycol (ZnDPBG), an inhibitor of heme oxygenase (HO), was used to inhibit HO activity in vivo. It was found that the blood pressure of rats with HO inhibition was significantly elevated, and plasma levels of adrenaline, noradrenaline, endothelin, nitrate and nitrite were significantly increased. HO activity and HbCO formation within vascular smooth muscle tissues were significantly inhibited after administration of ZnDPBG. Furthermore, administration of exogenous CO into HO inhibiting rats led to MABP decrease, but injection of HO substrate, heme-L-lysinate, had no effect on HO inhibition-induced hypertension. In spontaneously hypertensive rats, injection of exogenous CO resulted in a significant decrease of MABP, and heme-L-lysinate had a similar effect with exogenous CO. These data show that HO/CO system has an anti-hypertension biological action, suggesting that endogenous CO plays an important role in hypertension pathogenesis.

[Impairment in the phosphorylation of Ca(2+)-transport ATPase of rat liver endoplasmic reticulum during sepsis].

The phosphorylation of Ca(2+)-transport ATPase of rat liver endoplasmic reticulum (ER) during early and late septic shock induced by cecum ligation and puncture (CLP) was investigated by determining incorporation of [gamma-32P] ATP into Ca(2+)-ATP phosphoprotein intermediate. Hepatic endoplasmic reticulum was isolated by differential centrifugation with sucrose density gradient. The Ca(2+)-ATPase phosphoprotein intermediate was identified by SDS-PAGE. The results showed that the phosphorylation of Ca(2+)-ATPase (115 kD) was decreased respectively by 15-23% (P < 0.05) and 17-27% (P < 0.05) at 9 h (early sepsis) and 18 h (late sepsis), following the CLP in the rough, intermediate and smooth ER preparations. Kinetic analysis using rough ER showed that the Vmax for Ca2+ and for ATP for the phosphorylation of Ca(2+)-ATPase were decreased dramatically during early and late sepsis, but without changes in the K(m) values. These results demonstrate that the phosphorylation of the phosphoprotein intermediate of Ca(2+)-ATPase in rat liver was impaired during different phases of sepsis.