多曲方丝弓生物力学特性的三维有限元研究

采用三维有限元法比较分析后倾弯多曲方丝弓、理想弓和 Ni Ti弓在无牵引力、长 类牵引力作用下的矫治效果 ,在此基础上研究多曲方丝弓的整体力学特性 ,揭示多曲方丝弓技术矫治特点 ,探讨其作用机理。结果表明 :(1)无牵引力时 ,以第一、二前磨牙之间为界 ,多曲方丝弓矫治分别使前后牙向前后倾斜 ,且对前牙有压低作用 ;理想弓 (ss方弓 )与 Ni Ti弓矫治力的方向相同但大小不同 ,Ni Ti弓的作用更趋柔和 ,对前牙有轻微伸长作用 ,对后牙有一定压低作用 ,且使磨牙后倾、其余牙前倾。 (2 )长 类牵引时 ,三种弓丝对后牙的后倾作用有所增大 ,但 Ni Ti弓增加比例最大 ;多曲弓使切牙前倾 ,其余牙均向后倾 ;理想弓和 Ni Ti弓则没改变牙的倾斜方向。 (3)无论是预应力单独作用或预应力与牵引力同时作用 ,在牙根上产生的最大压应力均呈现出理想弓矫治时最大、Ni Ti弓居中而多曲弓最小。由此从理论上证明 ,多曲方丝弓矫治技术有利于下颌 Spee氏曲线的整平和牙齿的个别调控 ;对牵引力的传递作用强 ;同时矫治力柔和持久。     

A national surveillance study of the current status of reirradiation using brachytherapy in Japan

PurposeThis study aimed to explore the current status and pattern of practice for reirradiation using brachytherapy (ReRT-BT) through a survey in Japan.Materials and MethodsWe distributed an e-mail-based questionnaire to 153 institutions equipped with high-dose-rate brachytherapy facilities.ResultsWe received responses from 76 institutions (49.7%). Forty-three of these institutions performed ReRT-BT and 42 institutions (55%) performed ReRT-BT during 2009–2018. However, 29 of the 42 institutions (69%) reported difficulty in obtaining ReRT-BT case information from their respective databases. Almost all the institutions encountered insufficient database system to extract details about the ReRT-BT cases. Responses from 33 institutions included the number of ReRT-BT cases; this increased from 90 in the period 2009–2013 (institution median = 0.5; 0–16) to 172 in the period 2014–2018 (institution median = 2; 0–26). Nine institutions had to perform ReRT-BT for more than one case per year. The major location for cancer treatment was the pelvis (94%), followed by the head and neck (5%) and others (1%). In six site-specific scenarios, barring uterine corpus cancer recurrence, more than 90% of radiation oncologists agreed to perform ReRT-BT, whereas other areas (head and neck, prostate, and rectal cancer) gained 16–37% agreement.ConclusionsThis decade saw an increase in the number of ReRT-BT cases in Japan and radiation oncologists’ interest in ReRT-BT as a viable therapeutic option. However, scarce availability, immature education system, and insufficient database system are barriers to further consensus building.     

A comparison of treatment planning techniques for low-dose-rate (LDR) prostate brachytherapy

PurposeThe purpose of this study was to compare low-dose-rate prostate brachytherapy treatment plans created using three retrospectively applied planning techniques with plans delivered to patients.Methods and MaterialsTreatment plans were created retrospectively on transrectal ultrasound (TRUS) scans for 26 patients. The technique dubbed 4D Brachytherapy was applied, using TRUS and MRI to obtain prostatic measurements required for the associated webBXT online nomogram. Using a patient's MRI scan to create a treatment plan involving loose seeds was also explored. Plans delivered to patients were made using an intraoperative loose seed TRUS-based planning technique. Prostate V₁₀₀ (%), prostate V₁₅₀ (%), prostate D₉₀ (Gy), rectum D_0.1cc (Gy), rectum D_2cc (Gy), urethra D₁₀ (%), urethra D₃₀ (%), and prostate volumes were measured for each patient. Statistical analysis was used to assess and compare plans.ResultsProstate volumes measured by TRUS and MRI were significantly different. Prostate volumes calculated by the webBXT online nomogram using TRUS- and MRI-based measurements were not significantly different. Compared with delivered plans, TRUS-based 4D Brachytherapy plans showed significantly lower rectum D_0.1cc (Gy) values, MRI-based 4D Brachytherapy plans showed significantly higher prostate V₁₀₀ (%) values and significantly lower rectum D_0.1cc (Gy), urethra D₁₀ (%), and urethra D₃₀ (%) values, and loose seed MRI-based plans showed significantly lower prostate V₁₀₀ (%), prostate D₉₀ (Gy), rectum D_0.1cc (Gy), rectum D_2cc (Gy), urethra D₁₀ (%), and urethra D₃₀ (%) values.ConclusionsTRUS-based 4D Brachytherapy plans showed similar dosimetry to delivered plans; rectal dosimetry was superior. MRI can be integrated into the 4D Brachytherapy workflow. The webBXT online nomogram overestimates the required number of seeds.     

低剂量X射线照射对荷人小细胞肺癌(NCI-H446)裸小鼠移植瘤细胞凋亡相关基因mRNA表达的影响

目的 研究低剂量照射（LDR）对荷人小细胞肺癌（NCI-H446）裸小鼠移植瘤细胞凋亡相关基因mRNA表达的影响。方法 对荷人小细胞肺癌裸小鼠进行全身深部X射线照射，采用原位杂交技术检测荷人小细胞肺癌裸小鼠移植瘤组织的p53、Bcl-2、Bax的mRNA表达水平。结果 D1（75mGy）、D2（4Gy）照射后，小细胞肺癌细胞的p53、Bax的mRNA表达呈上升趋势，Bcl-2的mRNA表达呈下降趋势，但与假照组（0 mGy）比较，无明显差异；D1＋D2组的p53、Bax的mRNA表达明显增多，Bcl-2mRNA表达显著下降，与假照组（0mGy）比较有统计学差异（P〈0．05）。结论 LDR在一定程度上可能上调小细胞肺癌细胞的p53、Bax的mRNA表达，下调了Bcl-2mRNA的表达，同时对其后的大剂量照射有协同作用。     

磷酸二酯酶4D基因单核苷酸多态性与脑卒中相关性研究

目的探讨中国哈尔滨地区汉族人群磷酸二酯酶4D（PDE4D）基因单核苷酸多态性（sin．glenucleotide polymorphism,SNP）87和SNP83与脑卒中之间的关系。方法采用多重聚合酶链-高温连接酶检测反应（PCR—LDR）,对哈尔滨地区122例脑卒中患者及44例对照者PDFAD基因单核苷酸多态性进行检测,并比较各组间等位基因及基因型频率分布的差异。结果SNP87基因型频率在脑卒中各组与对照组之间均未见显著性差异（P〉0．05）,脑卒中组C等位基因频率为87．30％,明显高于对照组,两组间有显著性差异（X^2=3．992,P〈0．05）;SNP83基因型频率在脑卒中各组与对照组之间均未见显著性差异（P〉0．05）,C等位基因频率在脑卒中各组中均略高于对照组,但统计学上无意义。结论PDE4D基因SNP87（rs2910829）与中国哈尔滨地区脑卒中的发生相关,C等位基因可能是脑卒中的危险因素;SNP83（rs966221）与脑卒中无相关性;LDR技术能准确可靠快速的进行SNP分型。     

A population-based study of cervix cancer: incidence, management and outcome in the Canadian province of Saskatchewan

Aims

To document the incidence, management and outcome of uterine cervix cancer in the Canadian province of Saskatchewan. To compare provincial results of low dose rate (LDR) and high dose rate (HDR) brachytherapy in this population.

Materials and methods

We carried out a retrospective population-based cohort study of all uterine cervix cancer cases in Saskatchewan diagnosed between 1985 and 2001. We used data from the provincial cancer registry for incident cases, the provincial death registry for vital status information and chart reviews for treatment and toxicity information.

Results

In total, 714 cases of uterine cervix cancer were identified. Stage distribution was IA 22.7%, IB 31.8%, II 19.1%, III 18.4%, IV 6.8%; 81.2% were squamous cell carcinoma, 13.4% adenocarcinoma, 1.5% adenosquamous, 0.9% small cell and 3.1% other. The annual crude incidence rate of uterine cervix cancer in Saskatchewan ranged from 6.5 to 12.3% between 1985 and 2001. The 5-year cause-specific survival rate ranged from 100% for stage IA1 to 22% for stage IV. One hundred and seven patients were treated with LDR and 37 with HDR with similar stage distribution. The 5-year cause-specific survival rate was 56% for HDR and 67% for LDR (P = 0.72). For 43 patients managed with external beam radiotherapy alone, outcome was poor for stage IIB to IIIB. The most common acute toxicities of radiation treatment were diarrhoea (60%) and abdominal cramps (12.5%). The common chronic toxicities were vaginal stenosis (5.5%) and small bowel obstruction (4%).

Conclusions

Our population-level outcomes are in keeping with published observed results and provide some of the first Canadian population-level data on HDR and LDR outcomes. We found no significant different in cause-specific survival between patients managed with HDR and LDR, although interpretation is limited by patient numbers. Our results for external beam radiotherapy alone emphasise the vital role brachytherapy plays in the management of cervical cancer.     

Long-term safety of lamivudine treatment in patients with chronic hepatitis B

BACKGROUND & AIMS: Data on the long-term safety of lamivudine are limited. The aim of this analysis was to determine the incidence of hepatitis flares, hepatic decompensation, and liver-disease-related (LDR) serious adverse events (SAE) during long-term lamivudine treatment. METHODS: We reviewed data on 998 patients with HBeAg-positive compensated chronic hepatitis B who received lamivudine for up to 6 years (median, 4 years) and 200 patients who received placebo for 1 year. RESULTS: Hepatitis flares occurred in 10% of the lamivudine-treated patients in year 1 and in 18%-21% in years 2-5. A temporal association between hepatitis flares and lamivudine-resistant mutations increased from 43% in year 1 to >80% in year 3. Ten hepatic decompensation events occurred in 8 (<1%) lamivudine-treated patients. Fifty-three (5%) lamivudine-treated patients experienced a total of 60 LDR SAEs. Four patients died, 2 from liver-related causes. The proportion of patients with a documented lamivudine-resistant mutation increased from 23% in year 1 to 65% in year 5. During each year of the study, patients with lamivudine-resistant mutations experienced significantly more hepatitis flares than patients without lamivudine-resistant mutations (P < 0.005). The occurrence of hepatic decompensation (0%-2%) and LDR SAEs (1%-10%) among patients with lamivudine resistance remained stable during the first 4 years with mutations and increased afterward to 6% (P = 0.03) and 20% (P = 0.009), respectively. CONCLUSIONS: This study demonstrated that lamivudine treatment for up to 6 years has an excellent safety profile in patients with HBeAg-positive compensated liver disease, but patients with long-standing lamivudine-resistant mutations may experience worsening liver disease.     

GDF-15基因rs4808793位点多态性与急性心肌梗死的相关性分析

目的：探讨生长分化因子-15（growth differentiation factor-15,GDF-15）基因rs4808793位点多态性与承德地区汉族人群中冠心病急性心肌梗死发病风险的相关性。方法：采用连接酶检测反应法（ligase detection reaction,LDR）的方法对112例急性心肌梗死患者和60例健康对照者GDF-15基因rs4808793位点进行多态性分析。结果：在心肌梗死组中,CC、CG、GG三种基因型频率分别为51.8%、42.9%、5.4%,在正常对照组中分别为50%、43.3%、6.7%;两组受试者rs4808793位点的CC、CG、GG基因型频率分布无统计学意义（X^2=0.142,P=0.932）。结论：本研究未发现GDF-15基因-3148C/G位点中CC、CG、GG三种基因型与承德地区汉族人群中冠心病急性心肌梗死的发病风险有明确相关性。