The conversion of injected glucose into renal glycogen and mucopolysaccharides

Summary Tritiated glucose has been injected into rabbits in various states of hydration. The renal papilla of all animals showed an uptake of the label, converted into glycogen, and into mucopolysaccharides, in a manner dependent on the water balance of the animal.In papillae of control animals, the glycogen of the collecting duct epithelial cells and the mucopolysaccharides of the interstitium were labelled.In papillae of animals in an aqueous diuresis, the collecting duct glycogen was lightly labelled and there was no label over the interstitium.Antidiuretic hormone caused a diversion of label from the collecting ducts into interstitial mucopolysaccharides.The significance of these findings, with respect to renal concentrating ability, is discussed.The author wishes to thank Dr. M. K. S. Hathorn for help with the statistical analysis. Mr. K. Gamblin and Mr. P. L. Hyam gave valuable technical assistance. This research formed a part of the work approved for the degree of Ph. D. (London).     

Intercellular communication in the rat anterior pituitary gland: an in vivo and in vitro study

The concept of "stimulus-secretion coupling" suggested by Douglas and co-workers to explain the events related to monamine discharge by the adrenal medulla (5, 7) may be applied to other endocrine tissues, such as adrenal cortex (36), pancreatic islets (4), and magnocellular hypothalamic neurons (6), which exhibit a similar ion-dependent process of hormone elaboration. In addition, they share another feature, that of joining neighbor cells via membrane junctions (12, 26, and Fletcher, unpublished observation). Given this, and the reports that hormone secretion by the pars distalis also involves a secretagogue-induced decrease in membrane bioelectric potential accompanied by a rise in cellular [Ca++] (27, 34, 41), it was appropriate to test the possibility that cells of the anterior pituitary gland are united by junctions.     

Electrodeless dielectrophoresis of single- and double-stranded DNA

Dielectrophoretic trapping of molecules is typically carried out using metal electrodes to provide high field gradients. In this paper we demonstrate dielectrophoretic trapping using insulating constrictions at far lower frequencies than are feasible with metallic trapping structures because of water electrolysis. We demonstrate that electrodeless dielectrophoresis (EDEP) can be used for concentration and patterning of both single-strand and double-strand DNA. A possible mechanism for DNA polarization in ionic solution is discussed based on the frequency, viscosity, and field dependence of the observed trapping force.     

Natural products as starting points for future anti-malarial therapies: going back to our roots?

Background

Population movements along the Thailand-Cambodia border, particularly among highly mobile and hard-to-access migrant groups from Cambodia and Myanmar, are assumed to play a key role in the spread of artemisinin resistance. Data on treatment-seeking behaviours, knowledge and perceptions about malaria, and use of preventive measures is lacking as characteristics of this population prevent them from being represented in routine surveillance and the lack of a sampling frame makes reliable surveys challenging.

Methods

A survey of migrant populations from Cambodia and Myanmar was implemented in five selected rural locations in Thailand along the Thai-Cambodian border using respondent driven sampling (RDS) to determine demographic characteristics of the population, migratory patterns, knowledge about malaria, and health-care -seeking behaviours.

Results

The majority of migrants from Myanmar are long-term residents (98%) with no plans to move back to Myanmar, understand spoken Thai (77%) and can therefore benefit from health messages in Thai, have Thai health insurance (99%) and accessed public health services in Thailand (63%) for their last illness. In comparison, the majority of Cambodian migrants are short-term (72%). Of the short-term Cambodian migrants, 92% work in agriculture, 18% speak Thai, 3.4% have Thai health insurance, and the majority returned to Cambodia for treatment (45%), self-treated (11%), or did not seek treatment for their last illness (27%).

Conclusion

Most highly mobile migrants along the Thai-Cambodia border are not accessing health messages or health treatment in Thailand, increasing their risk of malaria and facilitating the spread of potentially resistant Plasmodium falciparum as they return to Cambodia to seek treatment. Reaching out to highly mobile migrants with health messaging they can understand and malaria diagnosis and treatment services they can access is imperative in the effort to contain the spread of artemisinin-resistant P. falciparum.     

Airway cellularity, lipid laden macrophages and microbiology of gastric juice and airways in children with reflux oesophagitis

Background and methods

Human metapneumovirus (hMPV) is a recently discovered respiratory virus associated with bronchiolitis, pneumonia, croup and exacerbations of asthma. Since respiratory viruses are frequently detected in patients with acute exacerbations of COPD (AE-COPD) it was our aim to investigate the frequency of hMPV detection in a prospective cohort of hospitalized patients with AE-COPD compared to patients with stable COPD and to smokers without by means of quantitative real-time RT-PCR.

Results

We analysed nasal lavage and induced sputum of 130 patients with AE-COPD, 65 patients with stable COPD and 34 smokers without COPD. HMPV was detected in 3/130 (2.3%) AE-COPD patients with a mean of 6.5 × 10⁵ viral copies/ml in nasal lavage and 1.88 × 10⁵ viral copies/ml in induced sputum. It was not found in patients with stable COPD or smokers without COPD.

Conclusion

HMPV is only found in a very small number of patients with AE-COPD. However it should be considered as a further possible viral trigger of AE-COPD because asymptomatic carriage is unlikely.     

植物的遗传转化及其应用(英文)

近年来,植物遗传转化研究有了长足的发展。已经达到能够通过简单的遗传控制手段研究具有新表现型的植物,甚至达到进入商业化的程度。这些手段包括植物生物学的主要研究技术以及植物组织培养和树种改良的一些实用方法。尽管采用农瘤杆菌和鸟枪法等技术的植物遗传转化系统已经得到了广泛的应用,但是在如何开发具有能够得到控制表达的转基因高产植物方面,在如何使所得到的转基因植物远离遗传危害等方面,目前的转化系统遇到了极大的技术挑战。已经提出了各种各样的方法用于将新基因稳定地导入120多种不同植物的核基因组。本文将讨论这些遗传转化系统所需的生物学要求和实际应用方面的需求、基因转化和转基因表达的研究策略、遗传转化植物的鉴定以及转基因植物与大众的认可。本文将分为七个部分加以讨论:一、导言;二 、基因转化到细胞里的方法;三、植物遗传转化策略;四、植物遗传转化的鉴定;五、植物遗传转化的实际应用;六、转基因植物与环境;七、未来植物遗传转化的需求与发展方向。     

Properties of microtubule sliding disintegration in isolated tetrahymena cilia

Properties of the sliding disintegration response of demembranated tetrahymena cilia have been studied by measuring the spectrophotomeric response or turbidity of cilia suspensions at a wavelength of 350 nm relative to changes in the dynein substrate (MgATP(2-)) concentration. The maximum decrease in turbidity occurs in 20 muM ATP, and 90 percent of the decrease occurs in approximately 5.9 s. At lower ATP concentrations (1-20 muM), both the velocity and magnitude of the turbidity decreases are proportional to ATP concentration. The velocity data for 20 muM ATP permit construction of a reaction velocity curve suggesting that changes in turbidity are directly proportional to the extent and velocity of disintegration. At ATP concentrations more than 20 muM (50muM to 5mM), both velocity and magnitude of the turbidimetric response are reduced by approximately 50 percent. This apparent inhibition results in a biphasic response curve that may be related to activation of residual shear resistance or regulatory components at the higher ATP concentrations. The inhibitory effects of elevated ATP can be eliminated by mild trypsin proteolysis, whereupon the reaction goes to completion at any ATP concentration. The turbidimetric responses of the axoneme-substrate suspensions are consistent with the extent and type of axoneme disintegration revealed by electron microscope examination of the various suspensions, suggesting that the turbidimetric assay may prove to be a reliable means for assessing the state of axoneme integrity.     

Ultrastructural observations on the renal papilla of the rabbit

Summary Ultrastructural studies of renal papillae of New Zealand brown rabbits under different states of water balance indicate no morphological variation between control, antidiuretic and diuretic animals; the only exception being a decrease in the amount of glycogen in the collecting duct cells in the antidiuretic state and an increase in the diuretic.The light cells of the collecting ducts have a low electron density and show a paucity of organelles. These comprise mitochondria, Golgi apparatus, multivesicular bodies, sparse endoplasmic reticulum and free ribosomes. The centrally-placed, spherical nucleus demonstrates large numbers of nuclear pores. The lateral surfaces and bases of the cells have considerable infoldings which may have functional significance.The attenuated endothelial cells of the vasa recta are punctuated by fenestrations which are most frequently crossed by membrane. The cells contain micropinocytotic and pinocytotic vesicles.The loops of Henle in the papilla are lined by squamous cells which are extended longitudinally in the form of interdigitating processes. The bases of the cells of most loops are scalloped.The interstitial cells are embedded in an amorphous matrix containing occasional collagen fibres and strands of fibrillar material. The cells are irregular in outline and have moderately developed endoplasmic reticulum and Golgi apparatuses.Tight junctions between the cells of all collecting ducts, loops of Henle and vasa recta are a constant finding. All these tubular elements are surrounded by a prominent basement membrane; that associated with the loops of Henle tends to be multiplied, particularly at scalloped regions. The membrane associated with the vasa recta is single except at regions where it projects across the interstitium to the membranes of the collecting ducts and loops of Henle.The functional implications of these findings are discussed.     

Visualization of Flagella during Bacterial Swarming

When cells of Escherichia coli are grown in broth and suspended at low density in a motility medium, they swim independently, exploring a homogeneous, isotropic environment. Cell trajectories and the way in which these trajectories are determined by flagellar dynamics are well understood. When cells are grown in a rich medium on agar instead, they elongate, produce more flagella, and swarm. They move in coordinated packs within a thin film of fluid, in intimate contact with one another and with two fixed surfaces, a surfactant monolayer above and an agar matrix below: they move in an inhomogeneous, anisotropic environment. Here we examine swarm-cell trajectories and ways in which these trajectories are determined by flagellar motion, visualizing the cell bodies by phase-contrast microscopy and the flagellar filaments by fluorescence microscopy. We distinguish four kinds of tracks, defining stalls, reversals, lateral movement, and forward movement. When cells are stalled at the edge of a colony, they extend their flagellar filaments outwards, moving fluid over the virgin agar; when cells reverse, changes in filament chirality play a crucial role; when cells move laterally, they are pushed sideways by adjacent cells; and when cells move forward, they are pushed by flagellar bundles in the same way as when they are swimming in bulk aqueous media. These maneuvers are described in this report.Swarming is a common yet specialized form of surface translocation exhibited by flagellated bacteria and is distinct from swimming (23). When cells are grown on a moist nutrient-rich surface, they differentiate from a vegetative to a swarm state: they elongate, make more flagella, secrete wetting agents, and move across the surface in coordinated packs. Here we focus on the mechanics of bacterial swarming, as exhibited by the model organism Escherichia coli. Others have worked on swarm-cell differentiation in a variety of organisms, including Proteus, Salmonella, Pseudomonas, Serratia, Bacillus, and Vibrio. For example, screens for genes required for swarming in E. coli or Salmonella have been made by Inoue et al. (25) and Wang et al. (40, 41). Vibrio is a special case, because a single polar flagellum enables cells to swim while multiple lateral flagella promote swarming (32). For general reviews, see the work of Allison and Hughes (1), Shapiro (37), Fraser and Hughes (17), and Fraser et al. (16). Also see the work of Eberl et al. (15), Sharma and Anand (38), Harshey (18), Daniels et al. (11), Kaiser (26), O''Toole (33), and Copeland and Weibel (10).Swarming was first observed with Proteus mirabilis by Hauser (22), who named the genus for a sea god able to change his own form. Proteus is distinctive because cells switch periodically from the vegetative to the swarming state, building terraced colonies (36, 42). This is not observed with E. coli under the conditions used here, where swarms expand at a constant rate propelled by cells swimming vigorously in a monolayer behind a smooth outer boundary.Swarming in E. coli was discovered by Harshey, who found that K-12 strains, which lack the lipopolysaccharide O antigen, swarmed on Eiken agar (from Japan) but not on Difco agar (from the United States), presumably because the former is more wettable (19, 20). Chemotaxis is not required: cells lacking the chemotaxis response regulator CheY swarm perfectly well, provided that mutations in the motor protein FliM enable transitions between clockwise (CW) and counterclockwise (CCW) rotational states (31). It was suggested that these reversals promote wetness by causing cells to shed lipopolysaccharide.How do cells in E. coli swarms move across an agar surface? What are their flagella doing? We sought to answer such questions by performing a global analysis of videotaped data (of phase-contrast images) collected from 5 regions of 2 swarms, plotting body lengths, speeds, propulsion angles, local track curvatures, and temporal and spatial correlations, and we found that cells reorient on a time scale of a few tenths of a second, primarily by colliding with one another (13). Our previous report did not describe analyses of individual tracks or visualization of flagella. This aspect of the work is presented here.Most of the time, cells are driven forwards by a flagellar bundle in the usual way. Flagellar filaments from different cells can intertwine and form common bundles, but this is rare. However, cells in swarms do something not ordinarily seen with swimming cells: they back up. They do this without changing the orientation of the cell body by moving back through the middle of the flagellar bundle. This involves changes in filament shape (in polymorphic form), from normal to curly and back to normal. Polymorphic forms were classified by Calladine (7), on the basis of earlier work by Asakura (3), in terms of the relative lengths of 11 protofilaments, longitudinal arrays of protein subunits that comprise the filament. All polymorphic forms are helical, with some being left-handed (e.g., the normal form) and some being right-handed (e.g., the semicoiled and curly forms, which have half the pitch of the normal filament and half the pitch and half the amplitude, respectively). Transformations from one shape to another can be caused in various ways, e.g., by changes in pH, salinity, or temperature (21, 27, 28) or by application of torque (24). The changes observed with swarm cells are driven by the latter mechanism, when motors switch from CCW to CW rotation. When swimming cells tumble, polymorphic transformations also occur, in the order normal to semicoiled to curly and back to normal (14, 39). But we rarely see the semicoiled form with cells in swarms, and when it appears, it is quite transient. We wonder whether polymorphic transformations evolved to enable cells to escape confined environments when the only way out is to back up, keeping the filaments close to the sides of the cell body.     

Immunohistochemical expression of rabphilin-3A-like (Noc2) in normal and tumor tissues of human endocrine pancreas

Involvement of rabphilin-3A-like (RPH3AL), or Noc2, the potential effector of Ras-associated binding proteins Rab3A and Rab27A in the regulation of exocytotic processes in the endocrine pancreas has been demonstrated in experimental models. Noc2 expression together with other regulatory molecules of the exocytotic machinery in human tissues, however, has not been studied. We evaluated immunohistochemical expression of the key molecules of the exocytotic machinery, Noc2, Rab3A, Rab27A, and RIM2, together with the characteristic islet cell hormones, insulin and glucagon in normal and endocrine tumor tissues of human pancreas. Normal pancreatic islets were stained for all of these proteins and showed strong cytoplasmic localization. A similar pattern of strong cytoplasmic expression of these proteins was observed in the majority of endocrine tumors. By contrast, the exocrine portions of normal appearing pancreas completely lacked Rab27A staining and showed decreased expression of the proteins, Noc2, Rab3A, and RIM2. The staining pattern of Noc2 and Rab27A was similar to the staining pattern of glucagon-producing cells within the islets. The concomitant expression of Noc2 with these molecules suggests that Noc2 may serve as an effector for Rab3A and Rab27A and that it is involved in the regulation of exocytosis of the endocrine pancreas in humans.