中国成年男子大气中元素吸入量研究

目的 获得中国成年男子空气中46种元素日吸入量。方法 在我国4个不同膳食类型地区连续3日采集大气中PM10样品,预处理后,采用ICP-MS,ICP-AES等仪器测定其中46种元素浓度。结合人体呼吸动力学计算统计各元素每日吸入量取中位数作为全国代表值。结果 得到了中国成年男子空气中46种元素日吸入量。结论 获得我国成年男子大气中46种元素日吸入量,为补全我国参考人相应参数参考值和某些重要生物动力学参数提供探索性依据。     

放射工作人员职业内照射剂量系数变化分析

目的 通过对职业内照射剂数的变化分析,探讨其对放射工作人员内照射剂量估算的影响。方法 选取41种核素作为研究对象,汇总其过去和新发布的职业剂量系数,通过计算其剂量系数比值分析其剂量系数变化。结果 41种核素的职业内照射剂量系数均发生了变化,其比值范围为0.1～4.5,最大变化幅度达到10倍（比值等于0.1时）。结论 建议及时修订我国涉及职业内照射剂量系数的标准,更新其职业内照射剂量系数,以便进一步完善放射工作人员的职业健康监护工作。     

粪肠球菌临床株对泰利唑胺体外抗菌活性的研究

目的 评价泰利唑胺体外抗粪肠球菌的活性，探讨泰利唑胺不敏感粪肠球菌的耐药机制及其多位点序列分型分布情况。方法 收集2011年1月1日—2016年6月30日深圳市南山区人民医院临床分离的粪肠球菌菌株，使用自动化仪器法及微量肉汤稀释法对分离菌株的耐药性进行检测。应用聚合酶链式反应（PCR）方法检测恶唑烷酮类抗生素耐药基因的携带情况，并采用多位点序列分型（MLST）对分离菌株进行分型。结果 共获得289株粪肠球菌，来源科室主要为外科（57.4%），标本来源主要为中段尿（126株，43.6%）。289株粪肠球菌对泰利唑胺敏感率为94.1%，对氨苄西林、呋喃西林和万古霉素有较高的敏感性（敏感率为97.9%~99.7%）。MLST结果显示，共分为47个ST型，优势ST分型为ST16和ST179，分别占29.1%（84株）和24.9%（72株），在泰利唑胺不敏感粪肠球菌中，ST16的比例高于ST179（P<0.05）。共检出泰利唑胺不敏感粪肠球菌17株，其携带optrA基因比例高于敏感株。结论 泰利唑胺对粪肠球菌的抗菌活性整体优于利奈唑胺，但对携带optrA基因的粪肠球菌则未显示出良好的抗菌活性。     

中国土壤中元素经膳食向人体转移的研究

目的 计算元素从我国土壤经膳食向成年男子全身的转移系数和碱土元素、碱金属元素DF值。方法 依据本系列研究所获我国成年男子膳食元素摄入量更新值和68例尸体全身负荷量,并引用我国土壤背景值,按照UNSCEAR环境转移模式和观察比法分别计算了元素在土壤、膳食和全身三环节间转移系数和DF值。结果 获得了50种元素由土壤经膳食向全身的转移系数,碱土元素(包括Pb)和碱金属元素在这三环节间DF值。结论 这些元素的P₂₃或P₂₃₄都比P₃₄小得多;P₂₃、P₃₄和P₂₃₄分别以Hg、Ca和Se最高,而以Ce、In和Y最低;稀土元素的P₂₃和P₂₃₄都小于碱金属或碱土元素。碱土元素从土壤-膳食-全身的DF都小于1,自钙随原子序的增大或减小,DF值都呈递减趋势,铅DF值在锶和钡之间。碱金属元素铷或铯从土壤向膳食转移DF小于1,而由膳食向全身转移DF大于1。     

探讨影响DR图像质量因素及控制措施

目的 优化并合理应用数字化X射线摄影设备DR (digital radiography),以获得优质的医学诊断影像。方法 介绍DR设备的结构,参数及各种影响因素。结果 分析讨论了DR图像质量的诸多影响因素和图像质量控制的应对措施。结论 在应用DR设备时,应优化各种参数,操作者规范操作方能得到高质量的DR图像。     

粪样中241Am测量方法的探索

目的 对粪样中超铀核素²⁴¹Am的分析测量方法进行研究,初步建立粪样中²⁴¹Am的分析方法,为工作人员内照射监测提供技术支持。方法 利用自行研制的粪样取样器和碳化灰化炉对粪样采集处理;采用DGA树脂对粪样中²⁴¹Am进行分离纯化的方法研究,用²⁴³Am为示踪剂并采用正交法进行条件优化实验。结果 初步确定以6 Mol/LHNO₃为上柱酸度、0.6 mL/min上柱速度和解析体积为12 mL的最佳分离纯化的条件;同时基于ICP-MS对粪样进行质谱测量分析,确定了基于ICP-MS的²⁴¹Am的检出限为9.79×10^-4 Bq,测量结果理想,具有可行性。结论 本文建立的方法在一定程度上弥补了对粪样中²⁴¹Am测量方法研究的空缺,对内照射监测和分析人员保护有实际意义。     

Blue Phantom放疗三维水箱测量加速器TMR与PDD转换TMR的比较

目的 比较用Blue Phantom直接测量的TMR与PDD转换成的TMR的数据表的差别。方法 用两种方法分别获得TMR数据,用统计学方法进行比较。结果 两种方法获得的TMR数据差别不大(P>0.25),平均偏差为0.45%。结论 用测量PDD然后转换成TMR的方法获得TMR曲线更为简捷、方便。     

医疗照射中应重视的问题

目的 合理应用医疗照射,做到趋利避害。方法 依据国际以及我国相关标准。结果 介绍了医疗照射的特点、现状及其所致剂量,提出了医疗照射中应再关注的问题。结论 要确保医用辐射安全,必须坚持医疗照射的正当化和防护最优化原则。     

LiF热释光探测器的性能实验研究

目的 对常见的个人剂量计中使用的三种热释光探测器进行了剂量学性能比较实验。方法 根据国家标准GB-10264-88和实际需要。结合 比较了三种热释光探测器的发光曲线、探测阈、重复性和稳定性。结论 三种探测器均符合国家标准要求,但有些产品的性能有待完美,使同时各种探测器都应按其参数控制热处理程序。     

粪肠球菌分子分型特点及其与泰利霉素敏感性的关系

目的 了解临床分离的粪肠球菌分子分型特征及其与泰利霉素药物敏感性之间的关系。方法 收集深圳市南山医院2010-2016年不同临床标本分离的粪肠球菌320株,采用多位点序列分型技术进行分型,用微量肉汤稀释法测定菌株对泰利霉素的最低抑菌浓度,采用PCR检测耐药基因ermB的分布。结果 320株粪肠球菌分为48个ST型和56株新的ST分型,以ST16、ST179型为主。ST16型85株（26.6%）,其中72株（84.7%）ermB阳性,29株（34.1%）对泰利霉素敏感,10株（11.8%）中介,46株（54.1%）耐药;ST179型80株（25.0%）,其中71株（88.8%）ermB阳性,15株（18.8%）对泰利霉素敏感,4株（5.0%）中介,61株（76.3%）耐药。结论 该院粪肠球菌以ST16、ST179为优势菌株,该两型菌群高比例携带ermB基因,对泰利霉素耐药率较高。     

Protein requirements of man: obligatory urinary and fecal nitrogen losses in elderly women.

Eleven health elderly women, ranging in age from 67 to 91 years, were given an essentially protein-free diet for 8 to 10 days, to determine obligatory urinary and fecal nitrogen losses. Body cell mass (BCM) was calculated from whole body 40K, and basal metabolic rate was determined by indirect calorimetry. Urine was analyzed daily for nitrogen and creatinine, and fecal N was measured in pooled samples. Urinary N output reached a relatively stable-state level by day 6; the average of the last four daily measurements was taken as an estimate of obligatory urinary N loss. The obligatory urinary N was: 24.4 +/- 5.2 mg N/kg body weight; 89.5 +/- 17.1 mg N/kg BCM; 1.44 +/- 0.14 mg N/basal kcal; and 2.11 g N/g creatinine. Obligatory fecal N was 9.8 mg N/kg body weight. Comparison of these results with published data for young adults indicates that obligatory urinary N losses in elderly women are similar to those for young women when expressed per unit body weight but higher than young women and men when expressed per unit creatinine excretion and per unit BCM.     

Renal and gastrointestinal potassium excretion in humans: new insight based on new data and review and analysis of published studies

OBJECTIVES: Little is known about the relationship between the renal and gastrointestinal excretion of potassium in humans. This information is important in light of strong associations of potassium intake with hypertension and occlusive stroke. METHODS: We determined the relationship between fecal and urinary excretion of potassium under both fixed and variable potassium intakes using our unpublished archival data and published data of others. Twenty-five subjects were evaluated. RESULTS: On a fixed, low oral potassium intake (61.2 +/- 4.7 mmol/day; mean +/- SD), there was an inverse relationship between fecal and urinary potassium excretion (r = -0.66, p = 0.040). In studies in which potassium intake varied between 61-135 mmol/day, fecal and urinary potassium excretions were positively correlated (r = 0.58, p = 0.024). Considerable within-and-between-subject variation was observed in the relationship between fecal and urinary potassium excretion. CONCLUSIONS: Inter-individual variation in fecal potassium excretion may arise from both variation in dietary potassium intake and intrinsic individual differences in the renal versus gastrointestinal handling of potassium.     

锌代谢池—判断人体锌营养状况的可靠指标

用稳定性同位素锌(~(68)Zn和~(70)Zn)对2例志愿者进行了历时15周不同锌营养水平的代谢实验。结果表明,锌代谢池能正确地反映人体的锌营养状况。空腹和餐后血浆锌浓度的差别比单独测定空腹血浆锌浓度更为可靠。每日尿锌和粪锌的排泄量则有一定的局限性。粪便中内源性锌排泄量的测定对确定人体每日锌的供给量标准,具有一定的参考价值。     

锌代谢池—判断人体锌营养状况的可靠指标

用稳定性同位素锌(~(68)Zn和~(70)Zn)对2例志愿者进行了历时15周不同锌营养水平的代谢实验。结果表明,锌代谢池能正确地反映人体的锌营养状况。空腹和餐后血浆锌浓度的差别比单独测定空腹血浆锌浓度更为可靠。每日尿锌和粪锌的排泄量则有一定的局限性。粪便中内源性锌排泄量的测定对确定人体每日锌的供给量标准,具有一定的参考价值。     

The disaccharide effect of sucrose feeding on excretion of intravenously injected [1,2-3H]aldosterone and conjugated glucuronic acid in normotensive rats

The hypothesis tested was that feeding rats sucrose rather than invert sugar (50:50 mixture of glucose and fructose) or cornstarch would result in a more rapid excretion of glucuronides and tritium from intravenously injected [1,2-3H]aldosterone. Thirty 56-d-old male rats of the Sprague-Dawley strain were fed for 8 wk one of three diets containing 45% of dietary energy from sucrose, invert sugar or cornstarch; 15% of energy was from protein and 40% from fat. Body weights and systolic blood pressures were measured weekly. After 60 d of feeding the diets ad libitum, all rats were injected intravenously with [1,2-3H]aldosterone and the percent recovery of tritium in both urine and feces was determined over the next 4 d. Urinary and fecal excretion of both free and conjugated glucuronic acid was determined over those 4 d. Urinary excretion of sodium and potassium (mg/d) was also determined. There were no differences between groups in food or water intakes, body weights, systolic blood pressures, daily fecal weights and daily urine volumes. The cornstarch-fed group excreted less sodium and potassium than did the other groups (P less than 0.05). The sucrose-fed group had a greater 4-d excretion of tritium (urinary + fecal) than did the invert sugar- or cornstarch-fed groups (P less than 0.01). The sucrose-fed group had a greater percentage of excreted glucuronic acid that was conjugated (urinary + fecal) than did the invert sugar- or cornstarch-fed groups (P less than 0.05). These results tended to confirm the hypothesis.     

Effect of ascorbic acid on calcium elimination in humans

The long-term and short-term influence of large oral doses of ascorbic acid on the urinary excretion of calcium has been investigated. In the first experiment, daily doses of a total of 10 g of ascorbic acid were administered to healthy human subjects. Daily urinary samples of these subjects were collected before and during the treatment, and calcium contents of these samples were measured. Among the 22 subjects, 19 experienced no significant changes in urinary calcium levels during the ingestion of ascorbic acid, one subject experienced an increase, two had a decline. These changes in urinary calcium levels were relatively small and were within the changes from consuming normal diets. In the second experiment, urinary samples of 46 healthy subjects were collected during a period of 8 hours after the ingestion of 2 g of ascorbic acid (33 times the U.S. RDA). A significant increase in mean urinary calcium excretion from 48.2 +/- 25.1 mg to 58.3 +/- 28.0 mg in the 8-h time period was observed. Mean urinary volume and phosphorus were unchanged. Calcium levels of the initially low excretors were significantly elevated while the change in urinary calcium levels of the initially high excretors was not statistically significant following the administration of ascorbic acid. The results suggest that ascorbic acid has a short-term effect on the regulation of the absorption and metabolism of calcium in humans.     

Rapid gut transit time and slow fecal isoflavone disappearance phenotype are associated with greater genistein bioavailability in women

The bioavailability of soybean isoflavones varies widely among individuals due to many factors, including activities of gut microflora. To characterize factors that affect fecal isoflavone disappearance phenotype and isoflavone bioavailability in women, 35 Asian and 33 Caucasian women, 18-43 y of age, provided fecal samples for anaerobic incubation with isoflavones in vitro at two times 5 mo apart (Phases I and II). Diet, physical activity and health history were investigated at these times. A single dose of soymilk powder [1.2 mg (4.57 micromol) total isoflavone/kg body] was given to all subjects with breakfast in phase II. Daidzein and genistein from fecal incubations, urine and fecal samples were measured by reverse-phase HPLC. Three significantly different daidzein and two genistein disappearance phenotypes were identified from fecal isoflavone incubations. More Asians than Caucasians were identified within the high daidzein disappearance phenotype. Caucasians and Asians differed significantly in daily intake of red meat (0.3 +/- 0.1 vs. 1.0 +/- 0.1 servings/d), dairy foods (2.9 +/- 0.2 vs. 1.2 +/- 0.2 servings/d) and insoluble dietary fiber (3.6 +/- 0.3 vs. 1.4 +/- 0.3 g). BMI, maximal oxygen uptake (VO(2 max)) and physical activity level were significantly greater in Caucasians than in Asians. Asian subjects of the low genistein disappearance phenotype had more rapid gut transit time (GTT) and greater isoflavone bioavailability as reflected in urinary genistein excretion than did Asians of the high genistein disappearance phenotype (GTT, 40 +/- 8 vs. 63 +/- 5 h; 11.0 +/- 2.7 vs. 4.0 +/- 1.7% of ingested genistein excreted in urine). Caucasians of both genistein disappearance phenotypes had longer GTT than did Asian subjects (84 +/- 5 vs. 56 +/- 6 h) and resembled Asians of the high genistein disappearance phenotype in genistein bioavailability. Relatively rapid GTT coupled with a low fecal isoflavone disappearance phenotype as occurred in Asian but not Caucasian subjects produced greater genistein bioavailability, as reflected in urinary genistein excretion.     

Methods and validity of dietary assessments in four Scandinavian populations

Average intakes of nonstarch polysaccharides (dietary fiber), foods, and nutrients were measured in representative samples of 30 men aged 50-59 in 4 Scandinavian populations with a 3-4 fold difference in risk for large bowel cancer. The assessment technique, a 4-day weighed record of food consumed and duplicate collections of all food eaten, was validated by chemical analysis of the duplicates, by measuring 24-hour urine and fecal nitrogen excretion, and by comparing the constituents of the urine samples collected during the survey with similar collections 1-2 weeks later. There were good agreements between estimates of fat and protein intake obtained by food-table calculations of the 4-day weighed record and the chemically analyzed duplicates. Urinary plus fecal nitrogen excretion was equal to estimated nitrogen intake during the survey, and no discernable changes in urinary output occurred after the survey, thereby implying that dietary habits had not changed as a result of the investigative technique. It is concluded that the dietary data are indicative of current patterns of food consumption and are sufficiently valid for comparison with data on cancer risk in the 4 areas.     

Urinary chromium excretion, diurnal changes, and relationship to creatinine excretion in healthy and sick individuals of different ages.

Since urine is the main excretory pathway for chromium, this study was conducted to compare in normal individuals the daily urinary chromium excretion with a 4 hr sample, to investigate diurnal fluctuations of urinary chromium and age-dependent relationship between urinary chromium and creatinine excretion. The results can be summarized as 1) there was no significant difference between the observed 24 hr chromium excretion and 24 hr excretion calculated from the one 4 hr samples, 2) a diurnal variation was observed when urinary excretion was expressed as chromium per minute, but no time-related variation could be established when chromium/creatinine (Cr/Cre) ratios in samples from three different periods of the same day were compared, although a significant positive correlation existed between urinary chromium and creatinine concentration, 3) the Cr/Cre ratio was found to be age-dependent, 4) in malnourished children the Cr/Cre ratio was very high and significantly different from that of normal infants, 5) This ratio for the eight diabetics was found to be significantly higher when compared with normal adults. On the basis of these results, it is suggested that morning 4 hr urinary chromium reflects the daily chromium excretion and that the Cr/Cre ratio of single urine samples obtained during this period is a reliable criterion in the evaluation of chromium nutrition of individuals in different conditions, provided that the influence of age is taken into consideration.