Expression and localization of clathrin heavy chain in Drosophila melanogaster

Clathrin-coated vesicles mediate cellular endocytosis of nutrients and molecules that are involved in a variety of biological processes. Basic components of the vesicle coat are clathrin heavy chain (Chc) and clathrin light chain molecules. In Drosophila melanogaster the chc gene function has been analyzed in a number of previous studies mainly using genetic approaches. However, the chc mRNA and protein expression patterns have not been studied systematically. We have generated an antibody that specifically recognizes Chc and we have analyzed chc RNA and protein expression patterns throughout embryonic and larval stages. We found that chc mRNA and protein are highly expressed from early stages of embryogenesis onwards, consistent with genetic studies predicting a maternal contribution of the gene function. During subsequent stages mRNA and protein are co-expressed in all embryonic cells; however we found an up-regulation in specific tissues including the gut, the salivary glands, tracheal system and the epidermis. In addition the central nervous system and the nephrocyte-like garland cells show strong Chc expression at late embryogenesis. In larvae Chc is highly expressed in garland cells, imaginal discs, fat body, salivary glands and the ring gland. Subcellularly, we found Chc protein in a vesicle-like pattern within the cytoplasm and at the plasma membrane. Co-labeling studies show that Chc is partially in contact with the trans-Golgi network and co-localizes with markers for early endocytosis. Together, the antibody may serve as a new tool to study the function of Chc in clathrin-dependent cellular processes, such as endocytosis.     

Brood-cell size does not influence the susceptibility of honey bees (Apis mellifera) to infestation by tracheal mites (Acarapis woodi)

Tracheal mites have been associated with the condition in honey bees that devastated colonies in Britain and Ireland in the early 1900s. The first outbreak of this condition, that became known as the ‘Isle of Wight’ disease, coincided with the period when brood-cell size was increased from about 5.0 mm to about 5.5 mm in width. We undertook an inoculation experiment over a 7-day period to establish if the act of increasing the brood-cell size could have triggered the onset of tracheal mites in honey bees. The standard-sized cells used had a cell width of 5.44 mm and the small-sized cells a width of 5.07 mm. Using callow (newly emerged) bees, from three colonies that had mixed cell sizes, we compared the susceptibility of bees reared in standard-sized cells with that of those raised in small-sized cells. The results indicated similar levels of female mite abundance (0.49 vs. 0.52 mites per bee) and mean fecundity (4.33 vs. 4.22 offspring per female mite), and produced no evidence of any difference in the overall susceptibility between the bees raised in the standard-sized cells versus small-sized brood cells.     

世界鹤类系统检索

本文把全世界的15种鹤,加以全面的系统检索。对鹤类不仅从其外观形态特征,而且从比较解剖及声调等,进行检索。这样做,认为还是首次的。     

预防性应用不同剂量羟考酮对腹腔镜胆囊手术拔管期应激反应的影响

目的:探讨预防性应用不同剂量羟考酮对腹腔镜胆囊手术(laparoscopic cholecystectomy,LC)拔管期应激反应的影响。方法:将75例接受LC的患者随机分为低、中、高剂量组,每组均25例。术毕15 min,低、中、高剂量组分别预防性静脉注射盐酸羟考酮0.1 mg/kg、0.15 mg/kg、0.2 mg/kg。比较各组拔管前(T_1)、拔管时(T_2)、拔管后5 min(T_3)、拔管后10 min(T_4)、拔管后30 min(T_5)血流动力学改变、麻醉苏醒时间、拔管情况及不良反应的发生情况。结果:与T_1时刻比较,各组T_2时刻收缩压(systolic blood pressure,SBP)、舒张压(diastolic blood pressure,DBP)、心率(heart rate,HR)均明显升高(P0.05),但中、高剂量组T_3时刻后SBP、DBP、HR均显著下降,恢复至T_1时刻水平(P0.05),各指标水平明显低于低剂量组(P0.05)。中剂量组与高剂量组各指标比较差异均无统计学意义(P0.05)。随着剂量羟考酮的增加,患者苏醒时间、拔管时间逐渐延长(P0.05);中、高剂量组拔管质量评分显著低于低剂量组(P0.05),而中、高剂量组间拔管质量评分比较差异无显著性(P0.05)。高剂量组恶心呕吐、呼吸抑制的发生率明显高于低剂量组,中、高剂量组追加镇痛药物的比例明显低于低剂量组(P0.05)。结论:预防性使用羟考酮可不同程度抑制LC术后拔管期应激反应,0.15 mg/kg羟考酮能够更好地维持患者血流动力学的稳定,促进患者早期苏醒,且安全性较高。     

Expression of plgR in the tracheal mucosa of SHIV/SIV-infected rhesus macaques

Polymeric immunoglobulin receptors (plgR) are key participants in the formation and secretion of secretory IgA (S-IgA),which is critical for the prevention of microbial infection and colonization in the respiratory system.Although increased respiratory colonization and infections are common in HIV/AIDS,little is known about the expression of plgR in the airway mucosa of these patients.To address this,the expression levels of plgR in the tracheal mucosa and lungs of SHIV/SIV-infected rhesus macaques were examined by real-time RT-PCR and confocal microscopy.We found that the levels of both PIGR mRNA and plgR immunoreactivity were lower in the tracheal mucosa of SHIV/SIV-infected rhesus macaques than that in non-infected rhesus macaques,and the difference in plgR immunoreactivity was statistically significant.IL-17A,which enhances plgR expression,was also changed in the same direction as that of plgR.In contrast to changes in the tracheal mucosa,plgR and IL-17A levels were higher in the lungs of infected rhesus macaques.These results indicated abnormal plgR expression in SHIV/SIV,and by extension HIV infections,which might partially result from IL-17A alterations and might contribute to the increased microbial colonization and infection related to pulmonary complications in HIV/AIDS.     

Airflow behavior changes in upper airway caused by different head and neck positions: Comparison by computational fluid dynamics

The feasibility of computational fluid dynamics (CFD) to evaluate airflow characteristics in different head and neck positions has not been established. This study compared the changes in volume and airflow behavior of the upper airway by CFD simulation to predict the influence of anatomical and physiological airway changes due to different head–neck positions on mechanical ventilation. One awake volunteer with no risk of difficult airway underwent computed tomography in neutral position, extension position (both head and neck extended), and sniffing position (head extended and neck flexed). Three-dimensional airway models of the upper airway were reconstructed. The total volume (V) and narrowest area (A_min) of the airway models were measured. CFD simulation with an Spalart–Allmaras model was performed to characterize airflow behavior in neutral, extension, and sniffing positions of closed-mouth and open-mouth ventilation. The comparison result for V was neutral <extension≈sniffing, and for A_min was neutral<extension<sniffing. A_min in sniffing position was nearly 3.0 times that in neutral position and 1.7 times that in extension position. The pressure drop and velocity increasing were more obvious in neutral than sniffing or extension position at the same airflow rate. In sniffing position, pressure differences decreased and velocity remained almost constant. Recirculation airflow was generated near the subglottic region in neutral and extension positions. Sniffing position improves airway patency by increasing airway volume and decreasing airway resistance, suggesting that sniffing position may be the optimal choice for mask ventilation.     

Comparative statistical mechanics of myosin molecular motors in rat heart, diaphragm and tracheal smooth muscle

Purpose

Statistical mechanics establishes a link between microscopic properties of matter and its bulk properties. A. Huxley's equations (1957) [1] provide the necessary phenomenological formalism to use statistical mechanics.

Methods

We compared statistical mechanics in rat diaphragm in tetanus (tet; n = 10) and twitch (tw; n = 12) modes, in heart in twitch mode (n = 20), and in tracheal smooth muscle in tetanus mode (TSM; n = 10). This powerful tool makes it possible to determine: (i) statistical entropy (S) which is related to the dispersal of energy and represents a measure of the degree of disorder in muscular system; (ii) thermodynamic force A/T (chemical affinity A and temperature T); (iii) thermodynamic flow (υ); (iv) entropy production rate (A/T × υ), which quantifies irreversible chemical processes generated by myosin crossbridge (CB) molecular motors.

Results

All muscles studied operated near equilibrium, i.e., A << 2500 J/mol and in a stationary linear regime, i.e., A/T varied linearly with υ. The heart operated farther from equilibrium than both diaphragm (tet and tw) and TSM, as attested by its high entropy production rate. S was of the same order of magnitude in heart and TSM but lower in diaphragm (tet and tw).

Conclusion

CB kinetics derived from A. Huxley's equations conferred a characteristic profile in terms of statistical mechanics on each muscle type. All studied muscles differed in terms of statistical entropy, chemical affinity, and entropy production rate. Stimulation mode (tet and tw) modulated CB kinetics and statistical mechanics. All muscle types operated near equilibrium and in a stationary linear regime.     

ICU 气管插管患者非计划拔管的原因、影响因素分析及护理对策

目的:了解导致ICU患者非计划拔管发生的原因及影响因素,探讨出科学有效的护理对策,为降低ICU患者非计划拔管的发生率提供依据。方法:本研究采用回顾性分析的方法,对我院2008年1月至2010年12月29例发生非计划拔管的患者进行分析,找出原因及影响因素,制定有针对性的护理对策。结果:2008年1月至2010年12月我院ICU患者非计划拔管率为4.2%,原因主要是患者自身的因素和医源性原因。影响因素依次为插管不耐受、患者气道梗阻、医护操作不当、插管方式错误、缺少有效的固定与约束及缺少有效镇静。结论:针对影响ICU患者发生非计划拔管的危险因素,制定有效的护理对策,可以切实的降低ICU患者非计划拔管发生率。     

Endothelin- and Sarafotoxin-Induced Phosphoinositide Hydrolysis in Cultured Canine Tracheal Smooth Muscle Cells

Abstract: The endothelins (ETs) and sarafotoxin are two structurally related classes of potently contractile peptides. To understand the mechanism of action of ETs, we have examined the effect of ETs and sarafotoxin on phosphoinositide (PI) hydrolysis in cultured canine tracheal smooth muscle cells (TSMCs). ET-1, ET-2, ET-3, and sarafotoxin caused dose-dependent accumulation of inositol phosphates (IPs) and tracheal smooth muscle contraction. BQ-123, an ET_A receptor antagonist, had a high affinity to block the ET-1-induced IP accumulation and tracheal smooth muscle contraction with pK_B values of 7.3 and 7.4, respectively. Pretreatment of TSMCs with cholera toxin impaired the ability of ET-1 and ET-2 to stimulate IP formation, whereas there was no effect by treatment with pertussis toxin. Stimulation of PI turnover by these peptides required the presence of extracellular Ca²⁺ and was blocked by treatment with EGTA. The addition of Ca²⁺(3–620 nM) to digitonin-permeabilized TSMCs directly stimulated IP accumulation. A further Ca²⁺-dependent increase in IP formation was obtained by inclusion of either GTPrS or ET-1. The combined presence of GTPrS and ET-1 elicited an additive effect on IP formation. Short-term exposure to phorbol 12-myristate 13-acetate (PMA, 1 μM) abolished the stimulation of PI hydrolysis induced by these peptides. The inhibitory effect of PMA on ET-induced response was reversed by staurosporine, a protein kinase C (PKC) inhibitor, suggesting that the inhibitory effect of PMA is mediated through the activation of PKC. Prolonged incubation of TSMCs with PMA resulted in a recovery of receptor responsiveness that may be due to down regulation of PKC. Inactive phorbol ester, 4α-phorbol 12, 13-didecanoate at 1 μM, did not inhibit this response. The site of this response was further investigated by examining the effect of PMA on AIF₄^?-induced IP accumulation in canine TSMCs. AIF₄^?-induced IP accumulation was inhibited by PMA treatment, suggesting that G protein(s) can be directly activated by AIF₄^?, which was uncoupled to phospholipase C by PMA treatment. These data conclude that ET-stimulated PI hydrolysis and tracheal smooth muscle contraction are mediated by the activation of ET_Areceptors coupling to a G protein and dependent on the external Ca²⁺. The transduction mechanism of ETs is sensitive to feedback regulation by PKC.     

Infection of Ixodes scapularis ticks with Rickettsia monacensis expressing green fluorescent protein: a model system

Ticks (Acari: Ixodidae) are ubiquitous hosts of rickettsiae (Rickettsiaceae: Rickettsia), obligate intracellular bacteria that occur as a continuum from nonpathogenic arthropod endosymbionts to virulent pathogens of both arthropod vectors and vertebrates. Visualization of rickettsiae in hosts has traditionally been limited to techniques utilizing fixed tissues. We report epifluorescence microscopy observations of unfixed tick tissues infected with a spotted fever group endosymbiont, Rickettsia monacensis, transformed to express green fluorescent protein (GFP). Fluorescent rickettsiae were readily visualized in tick tissues. In adult female, but not male, Ixodes scapularis infected by capillary feeding, R. monacensis disseminated from the gut and infected the salivary glands that are crucial to the role of ticks as vectors. The rickettsiae infected the respiratory tracheal system, a potential dissemination pathway and possible infection reservoir during tick molting. R. monacensis disseminated from the gut of capillary fed I. scapularis nymphs and was transstadially transmitted to adults. Larvae, infected by immersion, transstadially transmitted the rickettsiae to nymphs. Infected female I. scapularis did not transovarially transmit R. monacensis to progeny and the rickettsiae were not horizontally transmitted to a rabbit or hamsters. Survival of infected nymphal and adult I. scapularis did not differ from that of uninfected control ticks. R. monacensis did not disseminate from the gut of capillary fed adult female Amblyomma americanum (L.), or adult Dermacentor variabilis (Say) ticks of either sex. Infection of I. scapularis with R. monacensis expressing GFP provides a model system allowing visualization and study of live rickettsiae in unfixed tissues of an arthropod host.