Measurement of the secretion of technetium-99m hexamethylpropylene amine oxime into breast milk

There are no published data for the activity of technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) found 1in breast milk. The amount of radioactivity in breast milk following the administration of 500 MBq^99mTc-HMPAO for a brain perfusion study has been measured. The effective dose to the infant was calculated to be 0.26 mSv, so necessitating no interruption of breast feeding. Unbound^99mTc is readily secreted into breast milk and the effective dose will remain less than 1 mSv if the^99mTc-HMPAO labelling effici ency is 99% for the worse reported case, and could remain <1 mSv for the mean reported case for^99mTc-HMPAO labelling efficiencies down to 94%.     

Regulation of PaCO2 during rest and exercise: A modeling study

A nonlinear mathematical model of the CO₂ control system was used to examine a number of issues concerning the regulation of PaCO₂ during rest and exercise. To gain insight to the regulatory properties of the respiratory system, the open loop gain (G_l) and closed loop sensitivities S_i=ξPaCO₂/ξPiCO₂ and were calculated. Gl indicates the ability of a control system to regulate the controlled variable, PaCO₂ in the model. Si and Sv represent the change in PaCO₂ to unit changes in PiCO₂ and , respectively. Model predications were obtained for rest and various intensities of exercise for the following challenges to the respiratory system: (a) CO₂ inhalation, (b) i.v. CO₂ loading, (c) application of an external dead space, and (d) a shift in the resting operating point. Increasing exercise intensity produced a substantial decrease in Gl and increase in Si consistent with the hypothesis that exercise degrades the ability of the respiratory system to regulate PaCO₂. However, Sv decreased indicating that the respiratory system would actually be better able to regulate PaCO₂ if there were fluctuations in . Thus, Gl does not completely describe the regulatory characteristics of the respiratory control system. It is demonstrated that the regulatory characteristics of the respiratory system as described by Gl, Si, and Sv are complex and depend on the nature of the challenge. Techniques for systematically describing the regulatory properties of the CO₂ control system are described.     

High-frequency ventilation and conventional mechanical ventilation in newborn babies with respiratory distress syndrome: A prospective,randomized trial

Objective Morbidity and mortality remain high amongst babies ventilated for a respiratory distress syndrome (RDS). Whether newly developed ventilators allowing high frequency ventilation such as high frequency flow interrupted ventilation (HFFIV) could decrease the morbidity and the mortality was investigated in a randomized study.Design Preterm babies weighing 1800g suffering from RDS and ventilated by conventional mechanical ventilation (CMV) were randomized to be further ventilated either by CMV (group CMV) or by HFFIV (group HFFIV) when peak inspiratory pressure (PIP) on CMV was 20cmH₂O.Setting The study was undertaken in the neonatal intensive care unit of the Erasmus Hospital.Patients 24 patients entered into the investigation and were randomized but 2 patients were removed from the study because the switch over to HFFIV failed. Eight of the 12 CMV patients and 5 of the 10 HFFIV patients completed the study.Measurements and results Clinical variables, blood gas analysis and ventilatory variables were looked at. There were no differences in mortality, in incidence of air leaks and pulmonary complications or in blood gas analysis. Bronchopulmonary dysplasia was not decreased by the use of HFFIV.Conclusion It is concluded that HFFIV is safe although it offers no concrete advantages over CMV when applied as we did in a low pressure approach.     

Modelling the dynamic ventilatory response to hypoxia in humans

A two-component dynamic model was used to describe the ventilatory response to sustained hypoxia in humans. One component (X_s) represents the stimulating effects of hypoxia and the other component (X_d), the hypoxic ventilatory decline. The total ventilatory response to hypoxia is represented by the sum of the two components. A nonlinearity is included to account for the nonlinear steady-state ventilatory response to hypoxia. A sensitivity analysis of the model indicates that, with a step change in as the input, all the parameters can be estimated from the data except for the nonlinearity. The relative sensitivity of the parameters from the model analysis was confirmed in an experimental study. However, comparing steps into hypoxia versus steps out of hypoxia we found a decrease in the gains of both components. The most likely explanation for the decrease in the gains is that the combination of X_s and X_d is not entirely additive. Other models may be required to completely describe the ventilatory response to inputs more complex than steps.     

The effect of growth hormone on the growth failure of chronic renal failure

To investigate the effects of growth hormone (GH) on the reversal of growth failure in uremia, recombinant human GH (rhGH) was administered to rats with chronic renal failure (CRF). The dosage of rhGH was 3 IU/day (i.p.) for 13 days after the induction of CRF by 5/6 nephrectomy. Animals were classified into four groups: untreated nephrectomized rats (NX,n=40), GH-treated nephrectomized rats (NX+GH,n=18), sham-operated rats fed ad libitum (SHAMAL,n=27), and sham-operated rats pair-fed with 10 NX rats (SHAMPF,n=10). NX and NX+GH rats developed a similar and moderate degree of CRF, serum urea nitrogen being (mean±SEM) 49±3 and 54±4 mg/dl, respectively, compared with 16±4 and 19±0 mg/dl in SHAMAL and SHAMPF groups. Weight (56.0±3.3 g) and length (3.5±0.1 cm) gains of NX rats were lower than those of SHAMAL rats (94.2±4.0 g,P<-0.0001 and 4.1±0.2 cm,P<-0.01). Growth of the SHAMPF group and the matched NX rats was not significantly different. Weight (56.2±5.0 g) and length (3.4±0.2 cm) gains of NX+GH and NX rats were similar, the beneficial effect of GH therapy on growth being observed in only those animals with more severe degrees of uremia. This growth-promoting action resulted from greater food efficiency and not from stimulated food intake. The hypercholesterolemia seen in NX rats, 81±2 mg/dl versus 55±3 mg/dl in SHAMAL (P0.0001), was not increased in the NX+GH group, 87±3 mg/dl. There was a positive and significant correlation between serum cholesterol and serum urea nitrogen values in NX and NX+GH animals. This study suggests that growth impairment of mild CRF is mainly due to malnutrition and is refractory to GH administration. GH therapy improves the growth rate of animals with advanced CRF without aggravating their lipid abnormalities.     

灯盏花素纳米脂质体包封率测定方法研究

灯盏花素(breviscapine)是菊科植物短葶飞蓬(Erigeron breviscapus(vant.)Hand-Mazz)中提取的黄酮类有效成分。临床多用于治疗脑梗死、脑血栓、脑出血等。将药物制成脂质体,能帮助药物进入脑部,提高治疗指数。灯盏花素水溶性较差,直接溶于注射用水有一定困难,将其制成脂质体可以解决其难溶问题,提高药物稳定性及载药量,同时提高药物的靶向性及疗效。包封率是脂质体质量评定的重要指标,本实验建立了灯盏花素纳米脂质体包封率的测定方法,该法操作简单、可行、准确性较好。     

脂质-鱼精蛋白-DNA复合物的构建及其对细胞的体外转染

目的研究新型非病毒载体脂质-聚阳离子-DNA（LPD）复合物的制备方法及其对体外细胞的转染率。方法用薄膜-挤压法制备空白阳离子脂质体，与鱼精蛋白-DNA复合物在室温孵育后，得到LPD；用透射电镜观察其形态，用激光粒度仪测定其粒径和zeta电位；LPD与DNA酶I溶液在37 ℃下孵育不同时间后，用琼脂糖凝胶电泳观察其降解情况；用荧光法测定其包封率；用X-gal染色法考察了LPD对张氏（Chang）肝细胞，HepG2肝癌细胞和SMMC-7721肝癌细胞的转染率。结果LPD的形态近似于球体，平均粒径为143.5 nm，平均zeta电位为+32.6 mV；37 ℃下核酸酶作用2 h后，LPD中的DNA几乎无降解；平均包封率为93.42%；LPD对张氏（Chang）肝细胞、HepG2肝癌细胞和SMMC-7721肝癌细胞的转染率分别为(69±6)%，(43±7)%和(96.2±1.8)%。结论LPD是一种制备工艺简单、体外稳定性好、转染率高，具有应用潜力的非病毒载体系统。     

正常与病态下嗓音的客观指标的评价

对158例正常人和136例各种喉疾病患者连续元音[i]发声时的平均气流率、声强、频率、频率微扰商和发声效率同步进行了测定.并对各测定指标间的相互关系进行了探讨.频率微扰商是表示连续元音发声时声带振动相邻周期间的微细变动量;发声效率反映平均气流率与声能的有效转换率.在低、中和高强度发声时.随发声强度的提高,平均气流率.频率和发声效率随之提高而频率微扰商则变小.中等声强发声时.平均气流率与声强,声强与频率均呈正相关;而平均气流率与发声效率.声强(男性)和频率(女性)与频率微扰商均呈负相关.多数喉疾病患者显示出较正常人高的平均气流率和频率微扰商,发声效率则降低.当声强和频率作为参考指标时,平均气流率,频率微扰商和发声效率可作为评价喉发声功能的客观、定量指标.     

天然大豆磷脂制备热敏脂质体的方法及质量评价

目的：研究用天然磷脂替代合成磷脂制备热敏脂质体的方法及其质量评价。方法：以天然大豆磷脂为主要材料，胆固醇为附加剂，参照均匀设计原理选取影响脂质体热敏性的两个因素：磷脂与胆固醇的比例、制备温度和超声顺序(作为一个因素来考虑)，每个因素选取五个水平进行实验。采用逆相蒸发法制备氟脲脱氧核苷热敏脂质体并对其药物释放量、粒径大小及水中稳定性进行测定。结果：42℃时，药物释放量达到了被包封药物量的88．28％。水中放置4个月基本稳定，渗透率4．5％。结论：天然磷脂能替代合成磷脂制备具有良好相变温度的热敏脂质体。     

异丙酚复合瑞芬太尼应用于单肺通气麻醉的临床研究

目的：研究异丙酚复合瑞芬太尼联合应用单肺麻醉时对肺内分流、PaO2、清醒的影响．方法：选择胸外科行肺叶切除24例病人，随机分为两组，A组：异丙酚复合瑞芬太尼静脉全麻组12例；B组：异丙酚复合吸入异氟醚麻醉组12例。A组：静脉泵注异丙酚50μg／kg/min与瑞芬太尼0．05μg／kg/min混合液维持麻醉；B组：静脉泵注芬太尼0．05μg/kg／min与氟派利多2．5μg/kg／min混合液、复合吸人异氟醚1％～2％维持麻醉，分别在麻醉前、TLV 30min（TLV1），OLV 30min、OLV 60min．再次TLV 30min（TLV2）、手术结束等5个时点抽取动脉血和混合静脉血进行血气分析。结果：OLV开始后，Qs／Qt于TLV时高于麻醉前与TLV1时，OLV 30min、60min时Qs／Qt达最高，B组在OLV 30min、OLV 60min时，Qs／Qt高于A组（P〈0．01）。结论：异丙酚和瑞芬太尼联合麻醉能改善动脉血氧和减少肺内分流，且容易清醒。