Body hydration status and decompression sickness / 环境与职业医学

Hydration status refers to the balance between the intake and discharge of water in the body. When the ingested and discharged water are roughly equal and the body is in water balance, it is the normal hydration status, and when the water intake is too little or too much, it is the "dehydration" or "overhydration status". The hydration status of the body not only affects metabolism, but also affects the functions of the urinary system, cardiovascular system, nervous system, etc. In order to further clarify the relationship between body hydration status and decompression sickness (DCS), this paper reviewed relevant studies and analyzed the interaction between hydration and decompression safety during diving. The primary causes of dehydration in diving are "hyperbaric diuresis", "immersion diuresis", breathing dry gas, heat, and cold. Dehydration not only promotes the occurrence of DCS but also reduces the aerobic work efficiency and athletic performance of divers, as well as affects cognition and mood. A study found that appropriate rehydration before and during diving can reduce the risk of DCS, which possibly associates with the increase of blood volume, plasma surface tension, and vasoconstriction. Fluid therapy is also important for those who already have DCS. This paper analyzed the amount, nature, timing, and effect of rehydration involved in the above links, comprehensively sorted out the relationship between hydration and diving safety, summarized the existing problems, and provided reference for practical application and future research.

An algorithm of cone-beam CT registration based on dosimetry parameters of plans / 中华放射肿瘤学杂志

Objective:To improve the accuracy of cone-beam CT (CBCT) image registration by using a dose-guided registration algorithm based on multi-objective optimization.Methods:A total of 28 sets of CBCT images of 6 patients with lung cancer and 5 patients with cervical cancer admitted to Harbin Medical University Cancer Hospital in 2022 were retrospectively analyzed. Using the results of bone-based registration as the starting points for dose registration algorithm, the dose fluence weighted mean square errors of each displacement point in surrounding three-dimensional space were calculated, and the candidate displacement points were selected by unsupervised k-means clustering method. The three-dimensional dose distribution of each candidate displacement point was calculated by using the limited size pencil beam algorithm, and the dose histogram indexes were extracted as the optimization variables of the multi-objective optimization algorithm. After the Pareto optimal solution set obtained using multi-objective genetic algorithm, the optimal unique solution was then determined based on the predetermined objective weight scheme.Results:After dose optimization registration, the values of D 90%, D 95%, D 98%, D mean and conformity index (CI) of planning target volume (PTV) of lung cancer patients were increased by 0.23 Gy, 0.49 Gy, 1.05 Gy, 0.15 Gy, 0.03 compared with conventional registration, respectively, and no significant difference was found for the organs at risk (OAR). For cervical cancer cases, the values of D 90%, D 95%, D 98%, D mean and CI of PTV were increased by 0.72 Gy, 1.15 Gy, 2.53 Gy, 0.24 Gy, 0.05 compared with conventional registration, respectively, whereas the evaluation indexes of partial OAR were decreased by 1.06-1.81 Gy. Conclusion:The proposed dose-guided registration algorithm can improve the dose coverage for the target area, decrease the dose for OAR and reduce residual error of rigid registration algorithm, which can be implemented as part of online adaptive radiotherapy.

General Troubleshooting and Preventive Maintenance of the Digestive Electron Microscope System / 中国医疗器械杂志

OBJECTIVE@#Improve the integrity of the digestive electron microscope equipment and reduce the cost of equipment failure maintenance.@*METHODS@#By studying the composition and function of the digestive electron microscope system and analyzing the causes of common faults, a targeted preventive maintenance plan is developed, equipment users are graded, and a training system is established.@*RESULTS@#The user of the device can skillfully analyze the cause of the malfunction and timely deal with the sudden failure of the diagnosis and treatment, thereby reduce the risk of diagnosis and treatment and the investment in hospital maintenance.@*CONCLUSIONS@#Through the analysis and processing of the digestive electron microscope system, point detection leakage, grading training, preventive maintenance can significantly improve the equipment integrity rate, reduce the risk of clinical diagnosis and treatment, effectively reduce the number of equipment failures, and reduce maintenance costs.

Dosimetric analysis of three kinds of irradiation technique in radiotherapy of medulloblastoma / 实用肿瘤学杂志

Objective We aimed to explore the difference of dosimetry among intensity modulated radia-tion therapy(IMRT),volumetric modulated arc therapy(VMAT)and helical tomotherapy(TOMO)in the radio-therapy of medulloblastoma.Methods Ten children's patients with the medulloblastoma were selected and de-signed in this study.A clinically feasible radiotherapy plan was designed for IMRT(5 fields),VMAT and TOMO. Conformality index(CI),homogeneity index(HI),V107,maximum dose(Dmax),organ at risk(OAR)dose-volume level,monitor units and treatment time were used to analyze in these groups.Results CI,HI,V107,Dmaxand OAR of target areas were significantly superior to VMAT and IMRT in the TOMO group of target PTV for whole brain full radiotherapy.The organ at risk dose-volume level in the TOMO group was lower than that in VMAT and IM-RT(5 fields)groups(P<0.05).The TOMO group also had the most monitor units and the longest treatment time (P<0.05).Hence,the patients in the TOMO group could irradiate completely the whole brain and full spinal cord without moving treatment couch to avoid the error from the man-made movement in VMAT and IMRT(5 fields)treatments.Conclusion In the radiotherapy of medulloblastoma,the dose distribution of patients in the TOMO group are superior to the VMAT and IMRT groups(5 fields).However,the number of monitor units and treatment time is significantly increased during treatment,and its clinical effect needed to be further studies.

Dosimetric analysis of three kinds of irradiation technique in radiotherapy of medulloblastoma / 实用肿瘤学杂志

Objective We aimed to explore the difference of dosimetry among intensity modulated radia-tion therapy(IMRT),volumetric modulated arc therapy(VMAT)and helical tomotherapy(TOMO)in the radio-therapy of medulloblastoma.Methods Ten children's patients with the medulloblastoma were selected and de-signed in this study.A clinically feasible radiotherapy plan was designed for IMRT(5 fields),VMAT and TOMO. Conformality index(CI),homogeneity index(HI),V107,maximum dose(Dmax),organ at risk(OAR)dose-volume level,monitor units and treatment time were used to analyze in these groups.Results CI,HI,V107,Dmaxand OAR of target areas were significantly superior to VMAT and IMRT in the TOMO group of target PTV for whole brain full radiotherapy.The organ at risk dose-volume level in the TOMO group was lower than that in VMAT and IM-RT(5 fields)groups(P<0.05).The TOMO group also had the most monitor units and the longest treatment time (P<0.05).Hence,the patients in the TOMO group could irradiate completely the whole brain and full spinal cord without moving treatment couch to avoid the error from the man-made movement in VMAT and IMRT(5 fields)treatments.Conclusion In the radiotherapy of medulloblastoma,the dose distribution of patients in the TOMO group are superior to the VMAT and IMRT groups(5 fields).However,the number of monitor units and treatment time is significantly increased during treatment,and its clinical effect needed to be further studies.

Optimization of gradient factors in normal decompression algorithm / 军事医学

Objective To optimize the application principles of gradient factors(GFs) in decompression algorithm by analyzing its law of regulation.Methods The saturated value of compartments was listed and the limits of decompression were calculated to evaluate the effect of GFs on safety and efficiency of decompression.The anchor point of GFs was changed.Results and Conclusion A higher GF was recommended in shallow and short dives, while in deep and long dives a moderate low GF and decompression by oxygen was preferred.The modification of the anchor points of GFs can increase the risk of decompression sickness and should be used with caution.

Comparison of telomerase inhibition by antisense-oligodeoxynucleotide and RNAi / 白血病·淋巴瘤

Objective To select an efficient method to inhibit telomerase activity, antisenseoligodeoxynucleotide and plasmid-vector mediated RNAi against hTERT were used to inhibit telomerase activity. The inhibiting effects of the two methods were compared. Methods Against hTERT mRNA, siRNA and oligodeoxynucleotide were designed and transfected into K562 cells by liposome. Effective and specific siRNA strands were selected and then plasmid was constructed and transfected into K562 cells; followed by analysis of the results. Results hTERT mRNA were detected after the three chemo-synthesized strands were transfected. It was found that si-hTERT-1 and si-hTERT-2 were effective, but si-hTERT-3 had no effect. The inhibiting effect of hTERT mRNA lasted only 48 h and disappeared at 72 h. Two siRNA strands were sieved and plasmids were constructed and transfected into K562 cells. In the P-1 group, hTERT mRNA was 0.39±0.13 at 48 h, 0.57±0.32 at 72 h. In the P-2 group, hTERTmRNA was 0.55±0.20 at 48 h, 0.88±0.23 at 72 h.In the P-1 group, the relative telomerase activity was 0.42±0.07 at 48 h, 0.31±0.08 at 72 h. In the P-2 group was 0.49±0.27 at 48 h, 0.39±0.03 at 72 h. The best concentration of siRNA was 100 μmol/L. The best concentration of ASODN was 0.6 μ mol/L. hTERTmRNA was 0.42±0.16 at 24 h, 0.71±0.18 at 48 h. Relative telomerase activity was 0.52±0.002 at 24 h, 0.482±0.018 at 48 h. Conclusion Both ASODN and RNAi targeting hTERT can inhibit the expression of hTERT mRNA, and then inhibit telomerase activity. The inhibiting effect is closely relative to the targeting site. The inhibiting effect of RNAi is better than that of ASODN. RNAi has better efficiency and lasts for a longer time. Plasmid mediated RNAi has better inhibiting effect than the chemo-synthesized siRNA.