Receptor-recycling model of clearance and distribution of insulin in the perfused mouse liver

Summary After perfusion of mouse livers with A₁₄-¹²⁵I-insulin for designated intervals, an acid-wash technique was employed to separately measure the surface-bound (X_s) and intracellular (X_i) A₁₄-¹²⁵I-insulin, as well as intracellular degradation products (X_deg) of labelled insulin. From the perfusate concentrations (C_p) of A₁₄-¹²⁵I-insulin, the apparent intrinsic hepatic clearance of labelled insulin at a high dose (0.2 nmol/l) was shown to be 60% smaller than that at a low dose (0.018 nmol/l), indicating that the cellular uptake of insulin is remarkably nonlinear at the concentration range examined. From the time courses of C_p, X_s, X_i and X_deg, the hepatic insulin disposition was shown to be largely accounted for by the receptor-mediated endocytosis. The observed data at the low dose were analysed to estimate biochemical parameters, (i.e., total receptor number, endocytotic rate constant and intracellular degradation rate constant) according to receptor-recycling and non-receptor-recycling models, using a computer-aided optimization procedure. The receptor-recycling model could not only adequately explain the C_p, X_s, X_i and X_deg at the low dose, but also predict the C_p at the high dose. On the other hand, a non-receptor-recycling model, in which recycling of receptors was not assumed, could also explain the observed data at the low dose, but failed to predict the C_p at the high dose, indicating that the receptor recycling process is necessary to explain the hepatic insulin clearance at high insulin concentrations, at which hepatic insulin clearance should be limited by the rate of receptor recycling. However, the applicability of our model might be limited within the physiologic insulin concentrations, because of the negative co-operativity of insulin-receptor interaction and a high-capacity, non-degradative and more rapidly recycling pathway for receptors that may occur at high concentrations of insulin. In conclusion, we have developed a mathematical model of hepatic insulin clearance and distribution under physiological conditions, including receptor binding, receptor-mediated endocytosis and receptor recycling, which has been so far demonstrated using isolated hepatocytes.     

Pulmonary mechanics and outcome of neonates on ECMO.

Deciding when to wean neonates from extracorporal membrane oxygenation (ECMO) can be difficult. The usefulness of simple measurements of pulmonary mechanics e.g., dynamic compliance (Cdyn) has been questioned. We investigated the pulmonary mechanics of eight neonates using the interrupter technique, which allows the partitioning of pulmonary mechanics into compartments representing the conducting airways and more peripheral phenomena (viscoelastic properties and "pendelluft"). Three neonates required ECMO for a congenital diaphragmatic hernia (CDH), two for hyaline membrane disease (HMO), two for meconium aspiration syndrome (MAS), and one for pneumonia. All neonates with MAS, HMD, and pneumonia were successfully weaned from ECMO when their Cdyn was 0.3 mL/cmH2O/kg or greater [mean 0.34 +/- 0.06 (SEM)]. All three neonates with CDH died and their highest Cdyn was 0.21, 0.19, and 0.09 mL/cmH2O/kg respectively (mean, 0.16 +/- 0.037). The airway resistance (Raw) and the slower component of pressure change after interruption (delta Pdiff), a measure of the more peripheral phenomena of the lung, were not significantly different in those neonates who survived and those who did not. The values for delta Pdiff in all patients were higher than those in healthy neonates. However, the Raw was not different. This suggests that the major disturbance in pulmonary mechanics was distal to the conducting airways. Those neonates who were successfully weaned from ECMO had a significantly higher Cdyn 24-48 hours prior to decannulation. Considering the lung as a two-compartment model offers no advantages when compared to the one-compartment model for the prediction of the outcome of a neonate on ECMO.     

Mathematical aspects of the paternity index I=X/Y,especially in relation to the chance of non-exclusion of non-fathers

Summary In a previous paper the author mentioned some aspects of the paternity index I (=X/Y): Among false triplets the frequency of those with I equal to or higher than an (observed) I value of I ^x is considerably lower than 1/I ^x; among false triplets the mean value of I is equal to 1, and among non-excluded non-fathers it is equal to the inverse of the chance of non-exclusion; among true triplets the mean value of 1/I (=i) is equal to the chance of non-exclusion of non-fathers. In a statistical material rather strong deviations from some of these expectations were observed.In the present paper further characteristics of the distribution of I values were taken into consideration, and especially those that should hold if lnI would fit in with a normal distribution. It was supposed that with the aid of such a distribution the deviations mentioned above could be recognized as chance variability. It appears, however, that neither the logarithms of the paternity index, nor those of the zygosity index of twins (chosen as an analogous model that is more easily analysable than the paternity index) are really normally distributed. This, in turn, makes that estimates of probability of paternity, based on such a supposition, are of doubtful reliability. Besides it is concluded that also for other reasons other estimates than Essen-Möller's W (or I or i), as probability of first type errors, lead in practice to conclusions that are equally subdue to a priori suppositions as are W values and may be, in fact, much more erroneous than those.Special attention is paid to the statistical analysis of paternity studies with more than one alleged father, and it is concluded that in such cases the general formula that may be considered to be equivalent with Essen-Möller's formula for one-man paternity cases, i.e., W=X/(X+Y) or I/(I+1), must be W ₁=I ₁/(I+n); W ₂=I ₂/(I+n) etc. and certainly not W ₁=I ₁/(I+1); W ₂=I ₂/(I+1) etc.Dedicated to Prof. Dr. Erik Essen-Möller on the occasion of his 80th birthday     

Quantitative analysis of paradoxical inward rib cage movement during sleep in children

Paradoxical inward rib cage movement in children is quantified by the labored breathing index (LBI) on the respiratory inductive plethysmography. Labored breathing index during rapid eye movement sleep (REMS) in 59 children without obvious sleep disordered breathing (SDB) declined with age, and decreased to the mature low level at 35 months of age. The LBI was also found to reflect well the severity of SDB. Paradoxical inward rib cage movement, which was quantified by LBI, is concluded to be an important finding in diagnosing SDB in child patients.     

Esophageal pressure and apnea hypopnea index in sleep-disordered breathing

Severity of negative esophageal pressure (Pes) and apnea hypopnea index (AHI) were investigated in six cases of upper airway resistance syndrome (UARS) and 11 cases of obstructive sleep apnea syndrome (OSAS). The severity of negative Pes was represented by the highest peak (Pes Max) and the number of increased episodes (more than 13.5 cmH2O) per h (NPesI13.5). There was no significant correlation between Pes indices and AHI. Pes Max and NPesI13.5 were not different among severe OSAS (AHI > 30), mild OSAS (AHI < 30) and UARS. Apnea hypopnea index failed to represent the severity of negative Pes, which is an important aspect of the pathophysiology of sleep-disordered breathing.     

生孢梭菌孢子作为生物指示剂用于残存概率灭菌工艺验证的可行性

测定并分析生孢梭菌孢子在不同介质及不同温度下的耐热参数，评价生孢梭菌孢子的耐热特性及其作为生物指示剂在残存概率湿热灭菌工艺验证中的应用。     

支原体耐药性分析

目的：了解解脲支原体和人型支原体耐药情况及指导临床合理用药。方法：按试剂盒说明检测并观察结果。结果：对支原体敏感的药物依次是可乐必妥(96．7％)、美满霉素(85.6％)、强力霉素(78.5％)。对四环素、交沙霉素、乙酰螺旋霉素的耐药率分别为67．8％、61.8％、55．2％。结论：对支原体感染可首选可乐必妥、美满霉素、强力霉素；不宜选用四环素、交沙霉素、乙酰螺旋霉素。     

小细胞肺癌多药耐药基因的检测及临床应用研究

目的：探讨多药耐药集团（MDR1）在小细胞肺癌化疗中的作用和地位，方法：采用逆转录－多聚酶链式反应技术（RT／PCR）和免疫细胞化学染色法，检测了32例（初治原发癌21例和复治转移癌11例）小细胞肺癌患者血液中的MDR1mRNA水平和多药耐药蛋白（P－170）的表达，并对两种方法进行了比较。结果：初治的原发癌MDR1基因阳性表达率为14．29％，P－170蛋白阳性表达为14．27％，复治转移癌的MDR1基因阳性表达率为72．73％，P－170蛋白阳性表达为63．64％（P＜0．01），有显著性差异。MDR1的基因和蛋白两种而检测方法具有一定的一致性，以RT／PTR方法具有更强的敏感性，结论：复治转移癌组比初治组具有更普遍的抗药性，且主要是获得性抗药，MDR1基因表达可作为临床合理地制定化疗方案，预测化疗效果的重要参考指标。     

7种蛇毒小肽对临床分离耐（多）药结核分枝杆菌的体外活性研究

 目的检测7种从蛇毒分离的小肽是否对临床分离的耐药性结核分枝杆菌菌株具有活性。方法放射性方法检测蛇毒小肽对结核分枝杆菌的最小抑制浓度，细菌存活计数确证放射性方法的结果。结果7种蛇毒小肽对耐药性结核分枝杆菌菌株都有活性。其MIC值分别为(μg·mL_-1)：Opiophagus hannah 5.4，Naja atra 8.6，Bungarus fasciatus 6.4，Trimeresurus stejnegri 12.6，Protobothrops mucrosquamatus 11.8，Protobothrops jerdonii 7，Agksistrodon halys 4.2。结论这些结果是首次报道，为进一步设计和开发新来源的抗结核病新药提供了依据。