ObjectiveTo explore the influence of norepinephrine on the prediction of fluid responsiveness by passive leg raising (PLR) during septic shock. MethodsForty-six septic shock patients in intensive care unit of Nanjing Drum Tower Hospital were prospectively observed from September to November 2012. Among which 36 septic shock patients were enrolled with a positive PLR test (defined by an increase in stroke volume index ≥10%). A PLR test was performed at baseline (PLR1). A second PLR test (PLR2) was performed at returning to supine position for 10 min and the dose of norepinephrine was increased to maintain MAP ≥65 mmHg for 20 min. The changes of heart rate(HR),mean arterial pressure(MAP),central venous pressure(CVP),cardiac index(CI),stroke volume index(SVI),index of systemic vascular resistance(SVRI),global end-diastolic volume index(GEDVI),and cardiac function index(CFI) were monitored by transpulmonary thermodilution technique (PiCCO). ResultsPLR1 significantly increased SVI by (20.54±9.63)%,CI by (20.57±9.89)%,MAP by (7.64±5.77)%,and CVP by (25.83±23.39)%. As the dose of norepinephrine increased,SVI was increased by (16.97±9.06)%,CI by (16.78±8.39)%,GEDVI by (9.08±4.47)%,MAP by (28.07±12.48)%,and CVP by (7.86±8.52)%. PLR2 increased SVI by (13.74±8.79)%,CI by (13.79±9.08)%,MAP by (2.93±5.06)%,and CVP by (13.36±14.74)%. The PLR2 and the dose increase of norepinephrine augmented SVI to a significantly lesser extent than the PLR1 performed at baseline (both P<0.05). However,SVI increased by <10% in 6 patients while the baseline PLR was positive in these patients. ConclusionIn septic patients with a positive PLR at baseline,norepinephrine increases cardiac preload and cardiac output and influences the fluid responsiveness.
【Abstract】 Objective To investigate the effect of verapamil on apoptosis, calcium and expressions of bcl-2 and c-myc of pancreatic cells in ischemia-reperfusion rat model. Methods Wistar rats were randomly divided into three groups: control group （n=10）; ischemia-reperfusion group （n=10）; verapamil treatment group （n=10）. The anterior mesenteric artery and the celiac artery of rats in both ischemia-reperfusion group and verapamil treatment group were occluded for 15 min followed by 12-hour reperfusion. Verapamil （1 mg／kg） was injected via caudal vein to the rats in verapamil treatment group 15 min before occlusion and 1 hour after the initiation of reperfusion, respectively; and ischemia-reperfusion group was given the same volume of salient twice intravenously. Pancreatic tissues were collected from the dead rats after twelve hours since the reperfusion. The pathologic characters of pancreatic tissue were observed under light microscope; The level of calcium in the tissue was measured by atomic absorption spectrometer; TUNEL was used to detect apoptosis of pancreatic cells; and the expressions of c-myc and bcl-2 in the cells were also analyzed by immunohistochemistry technique and flow cytometry. Results The pathologic change in verapamil treatment group was less conspicuous than that of ischemia-reperfusion group. Both the calcium level and the number of apoptotic cells in verapamil treatment group were less than those of ischemia-reperfusion group 〔（411.1±55.8） μg/g dry weight vs （470.9±31.9） μg/g dry weight, P＜0.05 and （9.5±2.9）% vs （18.4±3.1）% 〕, P＜0.05. After taking verapamil, the number of apoptotic cells decreased, whereas the expressions of bcl-2 and c-myc increased. The fluorescent indexes of bcl-2 and c-myc in verapamil treatment group were significantly higher than those of ischemia-reperfusion group (1.72±0.11 vs 1.41±0.07, P＜0.05; 1.76±0.19 vs 1.55±0.13, P＜0.05. Conclusion Ischemia-reperfusion injury can induce apoptosis of pancreatic cells. Verapamil could protect the injured pancreatic tissue by reducing the level of calcium, stimulating the expressions of bcl-2 and c-myc and inhibiting apoptosis of pancreatic cells.
To introduce a rat model of the conversion of acute edematous pancreatitis (AEP) to necrotizing pancreatitis (ANP). One hundred and seven Sprague-Dawley rats were randomized in three experimental groups as follows: sham operation control group and AEP group and ANP group. AEP was induced by pancreatic duct ligation and exocrine stimulation, ANP was induced same as AEP，but with a large dose of dextran-110 (500mg/kg) intravenously. The serum concentration of amylase increased significantly in AEP group and ANP group. Cytosolic free Ca2+ concentration in isolated pancreatic acinar cells increased consistently after induction of ANP. Homorrhage, parenchymal necrosis and calcium deposits in acinar cells were observed in pancreas in ANP group. Ultrastructural examination showed desquamation and necrosis of the endothelium of the pancreatic capillary in ANP group. These results suggest that ischemia may induce the conversion of AEP to ANP via acinar cell Ca2+ overloading. The rat model would seem to be a suitable animal model for studying aggravating mechanism of acute pancreatitis.
Exercise intervention is an important non-pharmacological intervention for various diseases, and establishing precise exercise load assessment techniques can improve the quality of exercise intervention and the efficiency of disease prevention and control. Based on data collection from wearable devices, this study conducts nonlinear optimization and empirical verification of the original "Fitness-Fatigue Model". By constructing a time-varying attenuation function and specific coefficients, this study develops an optimized mathematical model that reflects the nonlinear characteristics of training responses. Thirteen participants underwent 12 weeks of moderate-intensity continuous cycling, three times per week. For each training session, external load (actual work done) and internal load (heart rate variability index) data were collected for each individual to conduct a performance comparison between the optimized model and the original model. The results show that the optimized model demonstrates a significantly improved overall goodness of fit and superior predictive ability. In summary, the findings of this study can support dynamic adjustments to participants' training programs and aid in the prevention and control of chronic diseases.
OBJECTIVE: To explore the possibility of repair long segmental bone defects and preventing infection with cefazolin loaded bone matrix gelatin (C-BMG). METHODS: C-BMG was made from putting cefazolin into BMG by vacuum adsorption and freeze-drying techniques. The sustaining period of effective drug concentration in vitro and in vivo was detected by inhabition bacteria, and the drug concentration in local tissues (bone and muscle) and plasma after implantation of C-BMG was examined by high performance liquid chromatography(HPLC). RESULTS: The effective inhibition time to staphylococcus aureus of C-BMG was 22 days in vitro, while 14 days in vivo. The drug concentration in local tissues(bone and muscle) were higher than that of plasma, and the drug concentration in local tissues was higher in early stage, later it kept stable low drug release. It suggested that C-BMG had excellent ability to repair segmental long bone defects. CONCLUSION: C-BMG can gradually release cefazolin with effective drug concentration and has excellent ability to repair segmental long bone defects. It may be a novel method to repair segmental long bone defects and prevent infection after the operation.
Objective To review the recent research progress of the bioreactor biophysical factors in cartilage tissue engineering. Methods The related literature concerning the biophysical factors of bioreactor in cartilage tissue engineering was reviewed, analyzed, and summarized. Results Oxygen concentration, hydrostatic pressure, compressive force, and shear load in the bioreactor system have no unified standard parameters. Hydrostatic pressure and shear load have been in controversy, which restricts the application of bioreactors. Conclusion The biophysical factors of broreactor in cartilage tissue engineering have to be studied deeply.
Objective To evaluate the relation of human immunodeficiency virus (HIV)-1 ribonucleic acid (RNA) loads in cerebrospinal fluid with central neurological diseases. Methods The inpatients with HIV-1 infection diagnosed by Public Health Clinical Center of Chengdu between January 1st, 2015 and March 1st, 2018 were retrospectively included. The included patients were divided into central neurological disease group and non-central neurological disease group, and high viral load group and low viral load group. The demographic data, CD4+ T lymphocyte count, routine detection of cerebrospinal fluid, HIV RNA load in cerebrospinal fluid and plasma of patients with and without central neurological diseases were observed and compared.Multiple logistic regression analysis was used to identify risk factors for central neurological diseases. Results A total of 367 patients were included. In the central neurological disease group, 210 cases (57.22%) were complicated with central neurological diseases, and cryptococcus infection was the most. Compared with the non-central neurological disease group, the increase rate of cerebrospinal fluid cell counts, cerebrospinal fluid cell counts, cerebrospinal fluid HIV RNA positivity and cerebrospinal fluid HIV RNA load were higher in the central neurological disease group (P<0.05). Logistic regression analysis showed that HIV RNA load in cerebrospinal fluid≥100 000 copies/mL and CD4+ T lymphocyte count<200 cells/mm3 were risk factors for central neurological diseases. Conclusion Cerebrospinal fluid HIV RNA load≥100 000 copies/mL is an independent risk factor for HIV/AIDS patients with central neurological diseases and clinical treatment should take this factor into consideration to reasonably optimize the selection of antiretroviral therapy.
Objective To study the effect of vancomycin-loaded polymethylmethacrylate (VCMPMMA) in the treatment of an experimental hemiprosthetic hip infectionof rabbits. Methods The infected hemiprosthetic hip joints of the rabbits underwent debridement and one-stage revision arthroplasty. Requested by the “fixed” method, 24 rabbits were equally divided into 2 groups: the control group and theexperimental group. The prostheses were fixed with PMMA in the control group, but with VCM-PMMA in the experimental group. X-ray films were taken immediately after operation, and then 4, 8, and 12 weeks after operation. The C reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) were measured before operation, then measured 1, 3, and 7 days after operation, and then 2, 4, 8, and 12 weeks after operation, i.e., they were measured at the above 8 time points. All the rabbits were sacrificed 12 weeks later. The cure rate of the infection was determined by the blood culture for the corresponding bacteria and the Rhodamine-labeled anti-Staphylococcus epidermidisimmune serum staining. Results The X-ray films revealed that6 hemiprosthetic hip joints were dislocated in the control group, but 3 in the experimental group; 58.3% and 16.7% of the hemiprosthetic hip joints were reinfected in the control group and the experimental group, respectively. At 8 weeks in the control group, the serum CRP level decreased to a greater extent than that measured at the time of debridement, but in the experimental group just at 2 weeks （Plt;0.01）. ESR remained elevated in the control group, but at 4 weeks ESR were significantly lowered compared with that measured at the time of debridement（Plt;0.01）. The test results for the pathogenic organisms revealed that the re-infection incidences were respectively 58.3% (7/12) and 16.7% (2/12) in the control group and the experimental group, with the successful revision rates of 41.7% and 83.3% respectively in the above 2 groups. The light microscopy revealed that therewas a heavy infiltration by the inflammatory cells in the reinfected tissues, but there was a proliferation of the fibrocytes in the tissues of the cured patients. Conclusion Onestage revision arthroplasty can significantly promote the control of the hemiprosthetic hip joint infection in rabbits by the use of VCM-PMMA.
To investigate the influence of the preload and supporting stiffness on the hearing compensation performance of round window stimulation, a coupling finite model composed of a human ear, an actuator and a support was established. This model was constructed based on a complete set of micro-computed tomography (Micro-CT) images of a healthy adult’s right ear by reverse engineering technology. The validity of the model was verified by comparing the model’s calculated results with experimental data. Based on this model, we applied different amplitude preloads on the actuator, and changed the support’s stiffness. Then, the influences of the actuator’s preload and the support’s stiffness were analyzed by comparing the corresponding displacements of the basilar membrane. The results show that after applying a preload on the actuator, its hearing compensation performance was increased at the middle and high frequencies, but was deteriorated at low frequencies; besides, compared with using the fascia as the actuator’s support in clinical practice, utilizing the titanium alloy to fabricate the support would enhance the hearing compensation performance of the round window stimulation in the whole frequency range.
Weightlessness in the space environment affects astronauts’ learning memory and cognitive function. Repetitive transcranial magnetic stimulation has been shown to be effective in improving cognitive dysfunction. In this study, we investigated the effects of repetitive transcranial magnetic stimulation on neural excitability and ion channels in simulated weightlessness mice from a neurophysiological perspective. Young C57 mice were divided into control, hindlimb unloading and magnetic stimulation groups. The mice in the hindlimb unloading and magnetic stimulation groups were treated with hindlimb unloading for 14 days to establish a simulated weightlessness model, while the mice in the magnetic stimulation group were subjected to 14 days of repetitive transcranial magnetic stimulation. Using isolated brain slice patch clamp experiments, the relevant indexes of action potential and the kinetic property changes of voltage-gated sodium and potassium channels were detected to analyze the excitability of neurons and their ion channel mechanisms. The results showed that the behavioral cognitive ability and neuronal excitability of the mice decreased significantly with hindlimb unloading. Repetitive transcranial magnetic stimulation could significantly improve the cognitive impairment and neuroelectrophysiological indexes of the hindlimb unloading mice. Repetitive transcranial magnetic stimulation may change the activation, inactivation and reactivation process of sodium and potassium ion channels by promoting sodium ion outflow and inhibiting potassium ion, and affect the dynamic characteristics of ion channels, so as to enhance the excitability of single neurons and improve the cognitive damage and spatial memory ability of hindlimb unloading mice.