Effect of PEEP on the mechanics of the respiratory system in ARDS patients.

In patients with adult respiratory distress syndrome (ARDS) we studied the effect of positive end-expiratory pressure (PEEP) on respiratory mechanics. We used the technique of rapid airway occlusion during constant flow (V) inflation to partition the total respiratory system resistance (Rrs) into the interrupter resistance (Rint,rs) and the additional resistance (delta Rrs) due to viscoelastic pressure dissipations and time constant inequalities. We also measured static (Est,rs) and dynamic (Edyn,rs) elastance of the respiratory system. The procedure was carried out in nine ARDS patients at different inspiratory V and inflation volumes (delta V) at PEEP of 0, 5, 10, and 15 cmH2O. We found that during baseline ventilation (delta V = 0.7 liter and V = 1 l/s), Est,rs, Edyn,rs, and Rint,rs did not change significantly with PEEP, whereas delta Rrs and Rrs increased significantly only with PEEP of 15 cmH2O. The increase of delta Rrs and Rrs with PEEP was positively correlated with the concomitant changes in end-expiratory lung volume (P < 0.001). At all levels of PEEP, under iso-delta V conditions, delta Rrs decreased with increasing V, whereas at a fixed V, delta Rrs increased with increasing delta V. A four-parameter model of the respiratory system failed to fully describe respiratory dynamics in the ARDS patients, probably due to nonlinearities.     

Histopathology and cytotoxicity as biomarkers in treated rats with cadmium and some therapeutic agents

The present study aimed to investigate the protective role of ascorbic acid (vitamin C) and zinc (Zn) against cadmium (Cd) induced histopathological changes in tissues of liver, kidney, lung and testis of rats as well as chromosomal aberrations. For this purpose, 60 male albino rats were divided into six groups; each group contained 10 animals. The first group served as control and was given only distilled water. The second and third groups received distilled water supplemented with 2 g ascorbic acid/l and 500 mg Zn/l, respectively. The fourth group received a daily oral dose containing 3 mg Cd/kg b.w. (1/30 LD₅₀). The fifth group received Cd + ascorbic acid (3 mg Cd/kg b.w. + 2 g ascorbic acid/l), while the sixth group received Cd + Zn (3 mg Cd/kg b.w. +500 mg Zn/l). The treatment in all groups lasted for 90 consecutive days. Rats exposed to cadmium showed severe histopathological changes in the liver, kidney, lung and testicular tissues as well as chromosomal aberrations such as: break, ring, centromeric separation and polyploidy. Co-treatment with zinc partially improved the histopathological changes and chromosomal aberrations while co-treatment with vitamin C exhibited a more protective role and markedly reduced tissues damage induced by Cd.     

High prevalence of buccal ulcerations in largemouth bass, Micropterus salmoides (Centrarchidae) from Michigan inland lakes associated with Myzobdella lugubris Leidy 1851 (Annelida: Hirudinea)

Widespread mouth ulcerations were observed in largemouth bass collected from eight inland lakes in the Lower Peninsula of Michigan during the summer months of 2002 and 2003. These ulcerations were associated with, and most likely caused by, leech parasitism. Through the use of morphological dichotomous keys, it was determined that all leeches collected are of one species: Myzobdella lugubris. Among the eight lakes examined, Lake Orion and Devils Lake had the highest prevalence of leech parasitism (34% and 29%, respectively) and mouth ulcerations (53% and 68%, respectively). Statistical analyses demonstrated that leech and ulcer prevalence varied significantly from one lake to the other. Additionally, it was determined that the relationship between the prevalence of ulcers and the prevalence of leech attachment is significant, indicating that leech parasitism is most likely the cause of ulceration. The ulcers exhibited deep hemorrhagic centers and raised irregular edges. Affected areas lost their epithelial lining and submucosa, with masses of bacteria colonizing the damaged tissues. Since largemouth bass is a popular global sportfish and critical to the food web of inland lakes, there are concerns that the presence of leeches, damaged buccal mucosa, and general unsightliness may negatively affect this important sportfishery.     

Field evaluation of transgenic wheat plants stably expressing the HVA1 gene for drought tolerance

The barley HVA1 gene, encoding a member of the group 3 late embryogenesis abundant (LEA) proteins, has previously been introduced into spring wheat cv. Hi-Line to determine its effect on drought tolerance (Sivamani E, Bahieldin A, Wraith JM, Al-Niemi T, Dyer WE, Ho T-HD, Qu R (2000) Improved biomass productivity and water use efficiency under water deficit conditions in transgenic wheat constitutively expressing the barley HVA1 gene. Plant Sci 155, 1–9). T4 progeny from six independent transgenic events (lines 111/1, 1/1, 11/2, 84, 765 and 1201) were tested in nine field experiments over six cropping seasons. In the first two seasons, the total biomass per plot and the grain yield per plot of line 111/1 were higher than those of line 1/1, and higher than those of the wild-type control in the second season. The grain yield per plot of line 11/2 was significantly lower than that of the transgenic lines 111/1 and 1/1 in the third season, and this line was not tested further. In the fourth season, the plant height and grain yield per plot of line 111/1 were significantly higher than those of the wild-type control. Under dryland conditions in the fifth season, line 111/1 showed significantly greater plant height, total biomass per plot and grain yield per plot than the wild-type control in at least two of the four locations, as well as across locations. In the sixth season, newly developed transgenic lines 1201 and 765 significantly overyielded the two original transgenic lines 111/1 and 1/1, the non-expressing transgenic line 84 as well as the wild-type control in the three yield attributes and leaf water measurement, namely relative water content (RWC). This result coincided with the rate of HVA1 transgene expression of the different genotypes. Differences in total seed storage protein concentrations between the transgenic lines and the wild-type control within or across environmental conditions were insignificant. These field trials show that the HVA1 gene has the potential to confer drought stress protection in transgenic spring wheat.     

Kinetic and stability properties of Penicillium chrysogenum ATP sulfurylase missing the C-terminal regulatory domain

ATP sulfurylase from Penicillium chrysogenum is a homohexameric enzyme that is subject to allosteric inhibition by 3'-phosphoadenosine 5'-phosphosulfate. In contrast to the wild type enzyme, recombinant ATP sulfurylase lacking the C-terminal allosteric domain was monomeric and noncooperative. All kcat values were decreased (the adenosine 5'-phosphosulfate (adenylylsulfate) (APS) synthesis reaction to 17% of the wild type value). Additionally, the Michaelis constants for MgATP and sulfate (or molybdate), the dissociation constant of E.APS, and the monovalent oxyanion dissociation constants of dead end E.MgATP.oxyanion complexes were all increased. APS release (the k6 step) was rate-limiting in the wild type enzyme. Without the C-terminal domain, the composite k5 step (isomerization of the central complex and MgPPi release) became rate-limiting. The cumulative results indicate that besides (a) serving as a receptor for the allosteric inhibitor, the C-terminal domain (b) stabilizes the hexameric structure and indirectly, individual subunits. Additionally, (c) the domain interacts with and perfects the catalytic site such that one or more steps following the formation of the binary E.MgATP and E.SO4(2-) complexes and preceding the release of MgPPi are optimized. The more negative entropy of activation of the truncated enzyme for APS synthesis is consistent with a role of the C-terminal domain in promoting the effective orientation of MgATP and sulfate at the active site.     

First record of Renibacterium salmoninarum in the sea lamprey (Petromyzon marinus)

Bacterial kidney disease (BKD), caused by Renibacterium salmoninarum, is a widespread problem with major implications for salmonid fish species. The mechanisms by which the bacterium has reached high levels of infection previously unrecorded in the Laurentian Great Lakes are presently unknown. Research involving reservoirs and mechanisms of R. salmoninarum transmission in fish is lacking because of the ecologic complexity of heterogeneous habitats and the lack of adequate funding. Herein, we report on the isolation of R. salmoninarum from the kidneys of the sea lamprey (Petromyzon marinus). The bacterium was cultured from kidneys of 16% and 4% of lampreys collected from two locations within the Lake Ontario watershed in 2003 and 2004, respectively. The identity of bacterial colonies was verified with the nested polymerase chain reaction and quantitative enzyme-linked immunosorbent assay.     

A versatile method for functionalization and grafting of 2-hydroxyethyl cellulose (HEC) via Click chemistry

This article describes a versatile method for the modification of 2-hydroxyethyl cellulose (HEC) involving azide-alkyne cycloaddition reaction to impart neutral (ester) and ionic (carboxylic acid and 1(ry) amine) functionalities. The synthetic approach involved, first the introduction of the azide functionality to HEC and then followed by its cycloaddition reaction with several alkyne terminated compounds: namely ethyl propiolate, 5-hexynoic acid and propargyl amine. Sequential Click reactions were also demonstrated to be feasible by the successful synthesis of polydimethylsiloxane (PDMS) grafted HEC containing neutral (ester) and ionic (carboxylic acid and 1(ry) amine) functionalities. The Click chemistry was then further utilized similarly to graft poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) segments to HEC to access its hydrophobic and hydrophilic analogs, respectively. AFM analysis revealed that while HEC itself formed uniform oval features, the PLA grafted HEC exhibited a brushlike architecture. The formation of these brushlike structures suggested that the HEC backbone exhibits an extended conformation with the side chains stretched out. The resulting polymeric materials were characterized by solution and solid state (13)C NMR and FTIR spectroscopy.     

Giardia lamblia: a new target for miltefosine

Giardia lamblia, the causative agent of giardiasis, is an intestinal infection with worldwide distribution and high rates of prevalence. Increased resistance of the parasite and the side effects of the reference drugs employed in the treatment of giardiasis make it necessary to seek new therapeutic agents. Therefore,the aim of this study was to examine the activity of hexadecylphosphocholine (miltefosine), a membrane active alkylphospholipid, that is licensed as an antileishmanial agent against giardiasis. The efficacy of miltefosine was evaluated both in vitro and in vivo in Swiss albino mice. Results of the in vitro testing revealed susceptibility of G. lamblia trophozoites to miltefosine with the following effective concentrations:EC50s of between 20 and 40 lM, and EC90s of between 20 and 80 lM. Immediate total lysis of the organisms was achieved by 100 lM. In vivo testing showed that oral administration of miltefosine,in a daily dose regimen course of 20 mg/kg for three successive days, to infected mice resulted in total elimination of the parasite from the intestine and amelioration of intestinal pathology. Scanning and transmission electron microscopy studies revealed that miltefosine induced severe morphological alterations to G. lamblia trophozoites, mainly at the level of cell membrane and adhesive disc. In conclusion,we believe that this is the first study highlighting G. lamblia as a possible new target for miltefosine.     

POC1A Truncation Mutation Causes a Ciliopathy in Humans Characterized by Primordial Dwarfism

Primordial dwarfism (PD) is a phenotype characterized by profound growth retardation that is prenatal in onset. Significant strides have been made in the last few years toward improved understanding of the molecular underpinning of the limited growth that characterizes the embryonic and postnatal development of PD individuals. These include impaired mitotic mechanics, abnormal IGF2 expression, perturbed DNA-damage response, defective spliceosomal machinery, and abnormal replication licensing. In three families affected by a distinct form of PD, we identified a founder truncating mutation in POC1A. This gene is one of two vertebrate paralogs of POC1, which encodes one of the most abundant proteins in the Chlamydomonas centriole proteome. Cells derived from the index individual have abnormal mitotic mechanics with multipolar spindles, in addition to clearly impaired ciliogenesis. siRNA knockdown of POC1A in fibroblast cells recapitulates this ciliogenesis defect. Our findings highlight a human ciliopathy syndrome caused by deficiency of a major centriolar protein.     

不受欢迎的生物多样性：香港的外来植物物种

香港早在19世纪中叶开始就有外来植物入侵的记录,迄今为止,已发现多达238种已归化的外来或怀疑为外来的植物,其中又以薇甘菊（Mikania micrantha)、五爪金龙（Ipomoea cairica)、假臭草（Eupatorium catarium)、大黍（Panicum maximum)等最常见,外来植物最常见于受人为干扰的生境,例如荒废农田及路旁等,而较少在天然林地生境及贫瘠的灌草丛中发现,外来植物的对本地生态系统的影响主要局限于低地生境,它们常形成单优种群,减少了生境及贫瘠的灌草丛中发现,外来植物对本地生态系统的影响主要局限于低地生境,它们常形成单优种群,减少少了生境及动植物的多样性,外来动物对香港原生植物影响最大的是于20世纪70年代入侵的松树线虫（Bur-saphelenchus xylophilus)。外来的脊椎动物也有可能对香港的植物被演替产生影响,目前香港的外来植物当中,有些在大陆较少分布或没有记录,作为华南最大的港口,香港对外来物种的引入扮演着重要的角色,因此制定控制外来种在香港及华南地区的引入及传播的政策及措施非常重要。