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941.
942.
Local Periocular Vaccination Protects against Eye Disease More Effectively Than Systemic Vaccination following Primary Ocular Herpes Simplex Virus Infection in Rabbits 总被引:1,自引:1,他引:0 下载免费PDF全文
Anthony B. Nesburn Susan Slanina Rae Lyn Burke Homayon Ghiasi S. Bahri Steven L. Wechsler 《Journal of virology》1998,72(10):7715-7721
Vaccination of experimental animals can provide efficient protection against ocular herpes simplex virus type 1 (HSV-1) challenge. Although it is suspected that local immune responses are important in protection against ocular HSV-1 infection, no definitive studies have been done to determine if local ocular vaccination would produce more efficacious protection against HSV-1 ocular challenge than systemic vaccination. To address this question, we vaccinated groups of rabbits either systemically or periocularly with recombinant HSV-2 glycoproteins B (gB2) and D (gD2) in MF59 emulsion or with live KOS (a nonneurovirulent strain of HSV-1). Three weeks after the final vaccination, all eyes were challenged with McKrae (a virulent, eye disease-producing strain of HSV-1). Systemic vaccination with either HSV-1 KOS or gB2/gD2 in MF59 did not provide significant protection against any of the four eye disease parameters measured (conjunctivitis, iritis, epithelial keratitis, and corneal clouding). In contrast, periocular vaccination with gB2/gD2 in MF59 provided significant protection against conjunctivitis and iritis, while ocular vaccination with live HSV-1 KOS provided significant protection against all four parameters. Thus, local ocular vaccination provided better protection than systemic vaccination against eye disease following ocular HSV-1 infection. Since local vaccination should produce a stronger local immune response than systemic vaccination, these results suggest that the local ocular immune response is very important in protecting against eye disease due to primary HSV-1 infection. Thus, for clinical protection against primary HSV-1-induced corneal disease, a local ocular vaccine may prove more effective than systemic vaccination. 相似文献
943.
Examination of the Kinetics of Herpes Simplex Virus Glycoprotein D Binding to the Herpesvirus Entry Mediator, Using Surface Plasmon Resonance 总被引:12,自引:8,他引:4 下载免费PDF全文
Sharon H. Willis Ann H. Rux Charline Peng J. Charles Whitbeck Anthony V. Nicola Huan Lou Wangfang Hou Lisa Salvador Roselyn J. Eisenberg Gary H. Cohen 《Journal of virology》1998,72(7):5937-5947
Previously, we showed that truncated soluble forms of herpes simplex virus (HSV) glycoprotein D (gDt) bound directly to a truncated soluble form of the herpesvirus entry mediator (HveAt, formerly HVEMt), a cellular receptor for HSV. The purpose of the present study was to determine the affinity of gDt for HveAt by surface plasmon resonance and to compare and contrast the kinetics of an expanded panel of gDt variants in binding to HveAt in an effort to better understand the mechanism of receptor binding and virus entry. Both HveAt and gDt are dimers in solution and interact with a 2:1 stoichiometry. With HveAt, gD1(306t) (from the KOS strain of HSV-1) had a dissociation constant (KD) of 3.2 × 10−6 M and gD2(306t) had a KD of 1.5 × 10−6 M. The interaction between gDt and HveAt fits a 1:1 Langmuir binding model, i.e., two dimers of HveAt may act as one binding unit to interact with one dimer of gDt as the second binding unit. A gD variant lacking all signals for N-linked oligosaccharides had an affinity for HveAt similar to that of gD1(306t). A variant lacking the bond from cysteine 1 to cysteine 5 had an affinity for HveAt that did not differ from that of the wild type. However, variants with double cysteine mutations that eliminated either of the other two disulfide bonds showed decreased affinity for HveAt. This result suggests that two of the three disulfide bonds of gD are important for receptor binding. Four nonfunctional gDt variants, each representing one functional domain of gD, were also studied. Mutations in functional regions I and II drastically decreased the affinity of gDt for HveAt. Surprisingly, a variant with an insertion in functional region III had a wild-type level of affinity for HveAt, suggesting that this domain may function in virus entry at a step other than receptor binding. A variant with a deletion in functional region IV [gD1(Δ290-299t)] exhibited a 100-fold enhancement in affinity for HveAt (KD = 3.3 × 10−8 M) due mainly to a 40-fold increase in its kinetic on rate. This agrees with the results of other studies showing the enhanced ability of gD1(Δ290-299t) to block infection. Interestingly, all the variants with decreased affinities for HveAt exhibited decreased kinetic on rates but only minor changes in their kinetic off rates. The results suggest that once the complex between gDt and HveAt forms, its stability is unaffected by a variety of changes in gD. 相似文献
944.
The Path from the RNA World 总被引:1,自引:0,他引:1
We describe a sequential (step by step) Darwinian model for the evolution of life from the late stages of the RNA world through
to the emergence of eukaryotes and prokaryotes. The starting point is our model, derived from current RNA activity, of the
RNA world just prior to the advent of genetically-encoded protein synthesis. By focusing on the function of the protoribosome
we develop a plausible model for the evolution of a protein-synthesizing ribosome from a high-fidelity RNA polymerase that
incorporated triplets of oligonucleotides. With the standard assumption that during the evolution of enzymatic activity, catalysis
is transferred from RNA → RNP → protein, the first proteins in the ``breakthrough organism' (the first to have encoded protein
synthesis) would be nonspecific chaperone-like proteins rather than catalytic. Moreover, because some RNA molecules that pre-date
protein synthesis under this model now occur as introns in some of the very earliest proteins, the model predicts these particular
introns are older than the exons surrounding them, the ``introns-first' theory. Many features of the model for the genome
organization in the final RNA world ribo-organism are more prevalent in the eukaryotic genome and we suggest that the prokaryotic
genome organization (a single, circular genome with one center of replication) was derived from a ``eukaryotic-like' genome
organization (a fragmented linear genome with multiple centers of replication). The steps from the proposed ribo-organism
RNA genome → eukaryotic-like DNA genome → prokaryotic-like DNA genome are all relatively straightforward, whereas the transition
prokaryotic-like genome → eukaryotic-like genome appears impossible under a Darwinian mechanism of evolution, given the assumption
of the transition RNA → RNP → protein. A likely molecular mechanism, ``plasmid transfer,' is available for the origin of
prokaryotic-type genomes from an eukaryotic-like architecture. Under this model prokaryotes are considered specialized and
derived with reduced dependence on ssRNA biochemistry. A functional explanation is that prokaryote ancestors underwent selection
for thermophily (high temperature) and/or for rapid reproduction (r selection) at least once in their history.
Received: 14 January 1997 / Accepted: 19 May 1997 相似文献
945.
Abstract: Brain inflammation includes microglial activation and enhanced production of diffusible chemical mediators, including prostaglandin E2 . Prostaglandin E2 is generally considered a proinflammatory molecule, but it also promotes neuronal survival and down-regulates some aspects of microglial activation. It remains unknown, however, if and how prostaglandin E2 prevents microglial activation. In primary culture, microglial activation is predicted by a characteristic pattern of whole-cell potassium currents and interleukin-1β production. We investigated if prostaglandin E2 could alter these currents and, if so, whether these currents are necessary for microglial activation. Microglia were isolated from mixed cell cultures prepared from neonatal rat brains and exposed to 0–10 µ M prostaglandin E2 and lipopolysaccharide for 24 h. Currents were elicited by using standard patch-clamp technique, and interleukin-1β production was measured by ELISA. Peak outward current densities in microglia treated with lipopolysaccharide plus prostaglandin E2 (10 n M ) were reduced significantly from those of cells treated with lipopolysaccharide alone. Prostaglandin E2 and 4-aminopyridine (a blocker of outward potassium currents) also significantly reduced interleukin-1β production. Thus, although prostaglandin E2 is classified generally as a proinflammatory chemical, it has complex roles in brain inflammation that include preventing microglial activation, perhaps by reducing the outward potassium current. 相似文献
946.
cis-Isomers of Cytokinins Predominate
in Chickpea Seeds throughout Their
Development 总被引:2,自引:1,他引:1 下载免费PDF全文
Robert Joseph Neil Emery Laurent Leport Joanne Edith Barton Neil Clifford Turner Craig Anthony Atkins 《Plant physiology》1998,117(4):1515-1523
Trans-isomers of cytokinins (CK) are thought to predominate and have greater biological activity than corresponding cis-isomers in higher plants. However, this study demonstrates a system within which the predominant CK are cis-isomers. CK were measured at four developmental stages in developing chickpea (Cicer arietinum L. cultivar Kaniva) seeds by gas chromatography-mass spectrometry. Concentrations were highest at an early endospermic fluid stage and fell considerably when the cotyledons expanded. The cis-isomers of zeatin nucleotide ([9R-MP]Z), zeatin riboside ([9R]Z), and zeatin (Z) were present in greater concentrations than those of corresponding trans-isomers: (trans)[9R-MP]Z, (trans)[9R]Z, (trans)Z, or dihydrozeatin riboside. Dihydrozeatin, dihydrozeatin nucleotide, and the isopentenyl-type CK concentrations were either low or not detectable. Root xylem exudates also contained predominantly cis-isomers of [9R-MP]Z and [9R]Z. Identities of (cis)[9R]Z and (cis)Z were confirmed by comparison of ion ratios and retention indices, and a full spectrum was obtained for (cis)[9R]Z. Tissues were extracted under conditions that minimized the possibility of RNase hydrolysis of tRNA following tissue disruption, being a significant source of the cis-CK. Since no isomerization of (trans)[2H]CK internal standards occurred, it is unlikely that the cis-CK resulted from enzymic or nonenzymic isomerization during extraction. Although quantities of total CK varied, similar CK profiles were found among three different chickpea cultivars and between adequately watered and water-stressed plants. Developing chickpea seeds will be a useful system for investigating the activity of cis-CK or determining the origin and metabolism of free CK. 相似文献
947.
Past changes in the taxonomy of Chaetobromus , a Cape grass with considerable fodder potential, reflect a history of instability due to inadequate past sampling and intergradation among taxa in most characters. This biosystematic study differs from earlier investigations by its much more intensive approach to sampling, taking into consideration inter- and intrapopulational variation in 75 anatomical, morphological and cytological characters, across a total of 169 samples. Both phenetic methods and population aggregation analysis revealed the existence of three major groups, approximating three formerly described taxa and reflecting divergent ecological strategies in Chaetobromus . However, continuity among groups in most characters and a lack of clear-cut diagnostic field characters argues against their recognition at species level. Thus, Chaetobromus is here described as monotypic, the type species, C. involucratus , comprising three subspecies C. involucratus ssp. involucratus, C. involucratus ssp. sericeus and C. involucratus ssp. dregeanus . 相似文献
948.
This paper describes a rapid method to identify the best solvent and carrier compound combinations with the highest extraction capability and the lowest microbial toxicity characteristics for product recovery from microbial fermentation. The extraction system has an aqueous phase, and an emulsion phase, which was a blend of sodium carbonate and organic phase [91% (v/v) organic solvent, 5% (v/v or wt/v) carrier compound, and 4% (v/v) surfactant Span 80]. Alamine 336, or tri-n-octylamine in n-heptane; Alamine 336, Alamine 304, or tributyl phosphate in hexane; and Alamine 304 or tributyl phosphate in iso-octane; Alamine 304 or Amberlite in xylene demonstrated high lactic acid extraction. For determination of bacterial toxicity of selected solvent and carrier compounds, Lactobacillus casei subsp. rhamnosus (ATCC 11443) was grown in LAF medium containing one of the selected organic solvent, carrier compound, and Span 80 in 250 ml flask at 37 °C and 125 rpm. Samples were collected regularly during 48 hour incubation, and measured for changes in cell density by absorbance at 620 nm, cell count using a fluorescent dye with flow cytometry, and lactic acid, and glucose concentrations by HPLC. Hexadecane:tributyl phosphate, n-dodecane:tri-n-octylamine, and kerosene:tri-n-octylphosphine oxide demonstrated the least microbial toxicity among the tested blends with excess solvent media. Whereas, hexanes:Alamine 304 and xylenes:Alamine 304 were nontoxic in solvent saturated media.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
949.
Pollen tube growth is a vital process for angiosperm fertilisation and is dependent on the presence of a tip-focused gradient
of cytosolic free calcium ([Ca2+]c). In order to clarify some of the target molecules which convey the Ca2+ signal information, we investigated calmodulin distribution during tube growth. Fluorescently labelled calmodulin was pressure
microinjected into pollen tubes and its distribution monitored by confocal microscopy. Calmodulin distributes evenly throughout
the cell, but some of its binding sites form a V-shaped collar behind the apical region. This specific association dissipates
upon growth arrest, and suggests an interaction of calmodulin with cytoskeletal-bound target proteins. The distribution of
calmodulin mRNA was also analysed by microinjection of fluorescently labelled mRNA. No specific pattern was observed, with
an even localisation in the body of tube and a lower concentration in the cell apex. Studies with localised application of
inhibitors/activators indicate that calmodulin plays a crucial role in tip elongation but does not direct tube orientation.
Received: 6 March 1998 / Revision accepted: 20 April 1998 相似文献
950.