Objective To explore the effect and mechanism of ultrashort wave (USW) for prevention and treatment of vascular crisis after rat tail replantation. Methods Eighty 3-month old female Sprague Dawley rats (weighing 232.8-289.6 g) were randomly divided into 5 groups. In each group, based on the caudal vein and the coccyx was retained, the tail was cut off. The tail artery was ligated in group A; the tail artery was anastomosed in groups B, C, D, and E to establish the tail replantation model. After surgery, the rats of group B were given normal management; the rats of group C were immediately given intraperitoneal injection (3.125 mL/kg) of diluted papaverine hydrochloride injection (1 mg/mL); the rats of groups D and E were immediately given the local USW treatment (once a day) at anastomotic site for 5 days at the dosage of 3 files and 50 mA for 20 minutes (group D) and 2 files and 28 mA for 20 minutes (group E). The survival rate of the rat tails was observed for 10 days after the tail replantation. The tail skin temperature difference between proximal and distal anastomosis was measured at pre- and post-operation; the change between postoperative and preoperative temperature difference was calculated. The blood plasma specimens were collected from the inner canthus before operation and from the tip of the tail at 8 hours after operation to measure the content of nitric oxide (NO). Results The survival rates of the rat tails were 0 (0/14), 36.4% (8/22), 57.1% (8/14), 22.2% (4/18), and 75.0% (9/12) in groups A, B, C, D, and E, respectively, showing significant overall differences among 5 groups (χ2=19.935, P=0.001); the survival rate of group E was significantly higher than that of group B at 7 days (P lt; 0.05), but no significant difference was found between the other groups by pairwise comparison (P gt; 0.05). At preoperation, there was no significant difference in tail skin temperature difference among 5 groups (P gt; 0.05); at 8 hours, 5 days, 6 days, and 7 days after operation, significant overall difference was found in the change of the skin temperature difference among groups (P lt; 0.05); pairwise comparison showed significant differences after operation (P lt; 0.05): group B gt; group D at 8 hours, group C gt; group D at 5 days, groups A, B, and C gt; group D at 6 days, groups B and C gt; groups A and E, and group B gt; group D at 7 days; but no significant difference was found between the other groups at the other time points (P gt; 0.05). Preoperative plasma NO content between each group had no significant difference (P gt; 0.05). The overall differences had significance in the NO content at postopoerative 8 hours and in the change of the NO content at pre- and post-operation among groups (P lt; 0.05). Significant differences were found by pairwise comparison (P lt; 0.05): group D gt; groups A, B, and C in the plasma NO content, group D gt; groups A and B in the change of the NO content at pre- and post-operation; but no significant difference was found between the other groups by pairwise comparison (P gt; 0.05). Conclusion Rat tail replantation model in this experiment is feasible. USW therapy can increase the survival rate of replanted rat tails, reduce skin temperature at 7 days, improve blood supply, increase the content of nitric oxide at the early period and prevent vascular crisis.
We studied the influence of electrode array parameters on temperature distribution to the retina during the use of retinal prosthesis in order to avoid thermal damage to retina caused by long-term electrical stimulation. Based on real epiretinal prosthesis, a three-dimensional model of electrical stimulation for retina with 4×4 microelectrode array had been established using the finite element software (COMSOL Multiphysics). The steady-state temperature field of electrical stimulation of the retina was calculated, and the effects of the electrode parameters such as the distance between the electrode contacts, the materials and area of the electrode contact on temperature field were considered. The maximum increase in the retina steady temperature was about 0.004℃ with practical stimulation current. When the distance between the electrode contacts was changed from 130 μm to 520 μm, the temperature was reduced by about 0.006℃. When the contact radius was doubled from 130 μm to 260 μm, the temperature decrease was about 0.005℃. It was shown that there were little temperature changes in the retina with a 4×4 epiretinal microelectrode array, reflecting the safety of electrical stimulation. It was also shown that the maximum temperature in the retina decreased with increasing the distance between the electrode contacts, as well as increasing the area of electrode contact. However, the change of the maximum temperature was very small when the distance became larger than the diameter of electrode contact. There was no significant difference in the effects of temperature increase among the different electrode materials. Rational selection of the distance between the electrode contacts and their area in electrode design can reduce the temperature rise induced by electrical stimulation.
【Abstract】Objective To investigate the effects of preservative temperature on pancreatic function and determine the optimal preservative temperature for pancreatic transplantation. MethodsCold pancreatic preservation was performed and a homologous male Wistar rat model of heterotopic total pancreaticoduodenal transplantation was established. The pancreas was preserved for 6 h in UW solution at specific temperatures(0 ℃, 4 ℃, 8 ℃ and 12 ℃). After preservation, pancreatic tissue was taken for histologic examination in every group. ATP and total adenine nucleotides (TAN) were determined by using high performance liquid chromatography (HPLC). Blood glucose(BG), serum amylase and lipase were measured 24 h after transplantation. And the activity of myeloperoxidase (MPO) in the pancreatic grafts was also measured at the same time. Besides, histological observation was performed. Results Microscopic studies showed that the histomorphological changes of pancreas in 4 ℃ group were less obvious than those in other groups. Tissual concentrations of ATP and TAN decreased gradually in 4 ℃ group, 0 ℃ group, 8 ℃ group, and 12 ℃ group after 6 h of preservation(PH＜0.05). The levels of BG, serum lipase and MPO increased gradually in 4 ℃ group, 0 ℃ group, 8 ℃ group, and 12 ℃ group(PH＜0.05). The activity of MPO in 4 ℃ group （1.19±0.16 U/g ）was significantly lower than that of the control group（0.26±0.09 U/g，PH＜0.05). Conclusion The temperature of 4 ℃ is most appropriate for hypothermic pancreatic preservation and can considerably alleviate cold ischemic injury of rat pancreas.
The effect of relaxation time in hyperbolic heat transfer model on the temperature field of microwave ablation of atrial fibrillation was investigated. And the results were compared with those calculated by Pennes model. A three-dimensional model of microwave ablation of atrial fibrillation was constructed. The relaxation time (τ) was 0, 1, 5, 8, 10, 15 and 20 s, respectively. And the temperature field of myocardial tissue was obtained. The results showed that the highest temperature of the hyperbolic model was 21.8 ℃ lower than that of the Pennes model at the beginning of ablation. With the increase of ablation time, the highest temperature tended to be the same. The lesion dimensions appeared at 3, 4, 6, 7, 8, 9, and 10 s, respectively after ablation. Therefore, the influence of hyperbolic model on temperature will decrease with the increase of the ablation time. At the beginning of ablation, the relaxation time will hinder the speed of myocardial thermal diffusion. The larger the relaxation time is, the slower the speed of thermal diffusion is. This study provides a reference for the application of hyperbolic model in microwave ablation of atrial fibrillation.
Objective To systematically review the efficacy of maternal body temperature preservation during caesarean section. Methods Databases including PubMed, EMbase, The Cochrane Library (Issue 2, 2015), WanFang Data, CBM and CNKI were searched from inception to July 2015 to collect randomized controlled trials (RCTs) of body temperature preservation in patients with caesarean delivery. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was performed using RevMan5.3 software. Results A total of 15 RCTs involving 1 331 patients were included. The results of meta-analysis showed that patients in the temperature preservation group had a smaller body temperature variation (MD= –0.22, 95%CI –0.32 to –0.13, P < 0.000 01) and a lower incidence of shivering (RR=0.53, 95%CI 0.42 to 0.67, P < 0.000 01) than patients in the control group. There were no statistical differences between the two groups in blood loss (MD= –13.77, 95%CI –33.95 to 6.42, P=0.18) and newborn Apgar score (MD=0.12, 95%CI –0.37 to 0.6, P=0.64). Conclusions Current evidence shows that body temperature preservation measures can better protect patients with caesarean delivery. Specifically, body temperature preservation measures could reduce patients’ body temperature variation and incidence of shivering but had no effect on blood loss and newborn Apgar score. Due to limited quality and quantity of the included studies, more high quality studies are needed to verify the above conclusion.
The temperature dependence of relative permittivity and conductivity of ex-vivo pig liver, lung and heart at 2 450 MHz was studied. The relative permittivity and conductivity of three kinds of biological tissues were measured by the open-end coaxial line method. The dielectric model was fitted according to the principle of least square method. The results showed that the relative permittivity and conductivity of pig liver, pig lung and pig heart decreased with the increase of tissue temperature from 20 to 80 ℃. The relative permittivity and conductivity models of pig liver, pig lung and pig heart were established to reflect the law of dielectric properties of biological tissue changing with temperature and provide a reference for the parameters setting of thermal ablation temperature field.
ObjectiveTo study the method of rapid and accurate measurement of body temperature in dense population during the coronavirus disease 2019 pandemic.MethodsFrom January 27th to February 8th, 2020, subjects were respectively measured with two kinds of non-contact infrared thermometers (blue thermometer and red one) to measure the temperature of forehead, neck, and inner side of forearm under the conditions of 4–6℃ (n=152), 7–10℃ (n=103), and 11–25℃ (n=209), while the temperature of axillary was measured with mercury thermometer under the same conditions. Taking the mercury thermometer temperature as the gold standard, the measurement results with non-contact infrared thermometers were compared.ResultsAt 7–10℃, there was no statistical difference among the forehead temperatures measured by the two non-contact infrared thermometers and the axillary temperature (P>0.05); there was no difference among the temperature measured by blue thermometer on forehead, neck, and inner side of forearm (P>0.05); no difference was found between the temperature measured by the red thermometer on forehead and inner side of forearm (P>0.05), while there was statistical difference between the temperatures measured by the red thermometer on forehead and neck (P<0.05). Under the environment of 11−25℃, there was no statistical difference among the forehead temperatures measured by the two infrared thermometers and the axillary temperature (P>0.05); the difference between the temperatures of forehead and inner side of forearm measured by the blue thermometer was statistically significant (P<0.05), while no difference appeared between the forehead and neck temperatures measured by the blue thermometer (P>0.05); there was no statistical difference among the temperatures of three body regions mentioned above measured by the red thermometer (P>0.05). According to the manual, the allowable fluctuation range of the blue thermometer was 0.3℃, and that of the red one was 0.2℃. The mean differences in measured values between different measured sites of the two products were within the allowable fluctuation range. Therefore, the differences had no clinical significance in the environment of 7–25℃. Under the environment of 4–6℃, the detection rate of blue thermometer was 2.2% and that of the red one was 19.1%.ConclusionsThere is no clinical difference between the temperature measured by mercury thermometer and the temperature measured by temperature guns at 7–10 or 11–25℃, so temperature guns can be widely used. In order to maintain the maximum distance between the measuring and the measured persons and reduce the infection risk, it is recommended to choose the inner forearm for temperature measurement. Under the environment of ambient temperature 4–6℃, the detection rate of non-contact electronic temperature gun is low, requiring taking thermal measures for the instrument.
Objective To investigate the effect of perioperative body temperature on the survival of skin flap grafting. Methods From July 2005 to November 2006, 50 cases of Ⅰ-Ⅱ grade patients undergoing elective skin flap grafting were randomly divided 2 groups. Pharyngeal temperature (PT) and skin temperature(ST) were monitored and recorded every 15 minutes. Operativetime, anesthetic time, time from the end of operation to extubation, the volume of blood transfusion, the volume of fluid transfusion and the flap survival 7 days after operation were recorded. In the experimental group, the body temperature was maintained in normal range with water market and forced air heater. In the control group， the body temperature was only monitored without any treatment. Results There were no significant differences in operating room temperature, operative time, anesthetic time, the volume of blood transfusion and fluid transfusion between 2 groups(Pgt;0.05). After induction, PT decreased gradually inboth groups during the first 45 minutes, compared with the time point of intubation(Plt;0.05),but there were no significant differences between the 2 groups(Pgt;0.05); and ST rose in both groups during the first45 minutes, compared with the time point of intubation (Plt;0.05). After 45 minutes of induction, in the experimental group, PT was in the normal range(36℃), and ST didn’t change compared with that of the timepoint of induction(Pgt;0.05). In the control group, both PT and ST decreasedgradually and timedependently compared with the time point of intubation (Plt;0.05). In the experimental group, PT and ST at each time point were higher than those in the control group (Plt;0.05). All the skin flap grafts survived in the experimental group, and skin flap grafts necrosed in 2 cases in the control group.Conclusion Keeping normal body temperature can improve the survival ofskin flap grafting. Therefore, the body temperature should be monitored and maintained in a normal range.
Patch clamp is a technique that can measure weak current in the level of picoampere (pA). It has been widely used for cellular electrophysiological recording in fundamental medical researches, such as membrane potential and ion channel currents recording, etc. In order to obtain accurate measurement results, both the resistance and capacitance of the pipette are required to be compensated. Capacitance compensations are composed of slow and fast capacitance compensation. The slow compensation is determined by the lipid bilayer of cell membrane, and its magnitude usually ranges from a few picofarads (pF) to a few microfarads (μF), depending on the cell size. The fast capacitance is formed by the distributed capacitance of the glass pipette, wires and solution, mostly ranging in a few picofarads. After the pipette sucks the cells in the solution, the positions of the glass pipette and wire have been determined, and only taking once compensation for slow and fast capacitance will meet the recording requirements. However, when the study needs to deal with the temperature characteristics, it is still necessary to make a recognition on the temperature characteristic of the capacitance. We found that the time constant of fast capacitance discharge changed with increasing temperature of bath solution when we studied the photothermal effect on cell membrane by patch clamp. Based on this phenomenon, we proposed an equivalent circuit to calculate the temperature-dependent parameters. Experimental results showed that the fast capacitance increased in a positive rate of 0.04 pF/℃, while the pipette resistance decreased. The fine data analysis demonstrated that the temperature rises of bath solution determined the kinetics of the fast capacitance mainly by changing the inner solution resistance of the glass pipette. This result will provide a good reference for the fine temperature characteristic study related to cellular electrophysiology based on patch clamp technique.
By studying the relationship between fingertip temperature changes and arterial function during vascular reactivity test, we established a new non-invasive method for detecting vascular function, in order to provide an assistance for early diagnosis and prevention of cardiovascular diseases. We customized three modules respectively for blood occlusion, measurement of finger temperature and blood oxygen acquisition, and then we established the hardware of data acquisition system. And the software was programmed with Labview. Healthy subjects [group A, n=24, (44.6±9.0) years] and subjects with cardiovascular diseases [group B, n=33, (57.2±9.9) years)] were chosen for the study. Subject's finger temperature, blood oxygen and occlusion pressure of block side during and after unilateral arm brachial artery occlusion were recorded, as well as some other regular physiological indexes. By time-domain analysis, we extracted 12 parameters from fingertip temperature signal, including the initial temperature (Ti), temperature rebound (TR), the time of the temperature recovering to initial status (RIt) and other parameters from the finger temperature signal. We in the experiment also measured other regular physiological body mass index (BMI), systolic blood pressure (SBP), diastiolic blood pressure (DBP) and so on. Results showed that 8 parameters difference between the two group of data were significant. based on the statistical results. A discriminant function of vascular function status was established afterwards. We found in the study that the changes of finger temperature during unilateral arms brachial artery occlusion and open were closely related to vascular function. We hope that the method presented in this article could lay a foundation of early detection of vascular function.