bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of food on microparasite transmission in the waterfleaDaphnia magna
Authors: Fels Daniel 
Published: March 2005

Studies on dynamics of trophic transmission usually refer to the predation of animals that contain parasites. Here, in contrast, I study the transmission of external stages of parasites namely of spores of the microsporidian gut parasitesGlugoides intestinalisand Micro1. These spores are filter fed by the waterfleaDaphniamagna and I was particularly interested in the effect of food on transmission success. It was hypothesized that food has a double impact on transmission success because of increased spore uptake on the one hand and increased spore defecation of infected waterfleas on the other. I tested for these assumed food effects in exposure experiments where transmission could occur naturally from infected to uninfected waterfleas in the presence or absence of food.The major assumptions were confirmed. In one system transmission success was increased fourfold in the presence of food and feeding infected hosts had lower spore loads. The other system showed evidence for these effects. Feeding activity correlated positively with food in both systems and spore loads in infected waterfleas partially determined spore loads in exposed waterfleas.I discuss the impact of food on infected and uninfected waterfleas in particular and on transmission success and epidemiology in general.
Phosphatidylcholine‐specific phospholipase C but not gamma interferon regulate gene expression and secretion of CC Chemokine Ligand‐2 (CCL‐2) by human astrocytes during infection by Toxoplasma gondii
Authors: Durand François , Brenier‐Pinchart Marie‐Pierre , Berger Francois , Marche Patrice N. , Grillot Renée , Pelloux Hervé 
Published: March 2005

SUMMARY We have used human astrocytoma‐derived cells to investigate the cellular responses of central nervous system cells to Toxoplasma gondii infection. At 24 h post inoculation, the secretion of CCL‐2 (or Monocyte Chemotactic Protein‐1) was augmented six‐fold over the control. This secretion was down‐regulated by D609, a specific inhibitor of phosphatidylcholine‐dependent phospholipase C (PC‐PLC), but not modulated by gamma interferon (IFN‐γ). Ribonuclease protection assay analyses showed significant down‐regulation of CCL‐2 mRNA production during infection by Toxoplasma gondii when cells were treated by D609. The mRNA levels of the seven other chemokines studied were not modified by D609. CCL‐2 seems to contribute to the cell recruitment during human cerebral reactivation of Toxoplasma gondii. Cellular production of this CC chemokine during toxoplasmosis may be regulated by a PC‐PLC‐dependent pathway.
Inflammatory antigens of Brugia malayi and their effect on rodent host Mastomys coucha
Authors: Dixit S. , Gaur R. L. , Khan M. A. , Saxena J. K. , Murthy P. S. R. , Murthy P. K. 
Published: March 2005

SUMMARY The study was aimed at identifying pro‐ and anti‐inflammatory cytokine releasing potential of Brugia malayi adult worm fractions and their role in filarial infection and pathogenesis. THP‐1 cells were incubated with soluble somatic Brugia malayi adult worm extract (BmAS) and its Sephadex G‐200 fractions BmAFI, BmAFII and BmAFIII and the effect of the fractions on parasitological, immunological and lymph node parameters was assessed in Mastomys coucha. BmAFII stimulated the pro‐inflammatory TNF‐α, IL‐1β and IL‐6 release; IL‐10 release was insignificant. Sensitization of animals with BmAFII and subsequent intraperitoneal implantation of worms enhanced CMI response. BmAFII also increased lymph node weight and cellularity, stimulated lymph node mast cells and eliminated intraperitoneally instilled worms. BmAFI stimulated several folds more release of IL‐10, whereas TNF‐α release was negligible. Sensitization with BmAFI elicited low CMI responses, moderately stimulated mast cells and facilitated survival of implanted adult parasites. Fifty percent of naive animals exposed to BmAFI showed oedematous lymph nodes and increased node weight. NCP‐bound molecules corresponding to BmAFI and II showed cytokine‐stimulating potential in vitro. It is concluded that BmAFII is protective and stimulates pro‐inflammatory cytokines, whereas BmAFI facilitates parasite survival and stimulates IL‐10.
Recombinant SSP4 protein from Trypanosoma cruzi amastigotes regulates nitric oxide production by macrophages
Authors: Ramos‐Ligonio A. , López‐Monteon A. , Talamás‐Rohana P. , Rosales‐Encina J. L. 
Published: March 2005

SUMMARY Acute infection with Trypanosoma cruzi is characterized by immunosuppression mediated by T cells and macrophages (Mφs). Nitric oxide (NO) production during the initial phase of acute infection might participate in the clearance of parasites by Mφs, whereas its overproduction during the late phase of acute infection would account for the immunosuppression observed. Trypanosoma cruzi molecules that might regulate the host responses have not been fully identified. Here, we demonstrate that active immunization with MBP::SSP4, a recombinant protein derived from a surface antigen specific of T. cruzi amastigotes (TcSSP4), was able to stimulate Ab production (IgG1, IgG2a, and IgG2b). On the other hand, MBP::SSP4 was able to stimulate NO production by peritoneal Mφs from BALB/c mice and Mφs from the J774 cell line. This effect was also observed at the level of inducible nitric oxide synthase (iNOS) detected by Western Blot. Furthermore, MBP::SSP4 was also shown to induce the expression of IL‐1α, IL‐6, IL‐12, IFN‐γ, and TNF‐α in normal animals, and IL‐10 in immunized animals. In addition the protein MBP::SSP4 was able to bind to the surface of PMφs and J774 Mφs. These results suggest that TcSSP4 could modulate Mφ NO production and this may represent a mechanism participating in the immunoregulatory processes during Chagas’ disease.
Potential transmission of West Nile virus in the British Isles: an ecological review of candidate mosquito bridge vectors
Authors: Medlock J. M. , Snow K. R. , Leach S. 
Published: March 2005

Abstract. West Nile virus (WNV) transmitted by mosquitoes (Diptera: Culicidae) infects various vertebrates, being pathogenic for birds, horses and humans. After its discovery in tropical Africa, sporadic outbreaks of WNV occurred during recent decades in Eurasia, but not the British Isles*. WNV reached New York in 1999 and spread to California by 2003, causing widespread outbreaks of West Nile encephalitis across North America, transmitted by many species of mosquitoes, mainlyCulexspp. The periodic reappearance of WNV in parts of continental Europe (from southern France to Romania) gives rise to concern over the possibility of WNV invading the British Isles.The British Isles have about 30 endemic mosquito species, several with seasonal abundance and other eco‐behavioural characteristics predisposing them to serve as potential WNV bridge vectors from birds to humans. These include: the predominantly ornithophilicCulex pipiensL. and its anthropophilic biotypemolestusForskål; tree‐hole adaptedAnopheles plumbeusStephens; saltmarsh‐adaptedOchlerotatus caspiusPallas,Oc. detritusHaliday andOc. dorsalis(Meigen);Coquillettidia richiardiiFicalbi,Culiseta annulataSchrank andCs. morsitans(Theobald) from vegetated freshwater pools;Aedes cinereusMeigen,Oc. cantansMeigen andOc. punctorKirby from seasonal woodland pools. Those underlined have been found carrying WNV in other countries (12 species), including the rarer British speciesAedes vexans(Meigen),Culex europaeusRamos et al.,Cx. modestusFicalbi andOc. sticticus(Meigen) as well as theAnopheles maculipennisMeigen complex (mainlyAn. atroparvusvan Thiel andAn. messeaeFalleroni in Britain). Those implicated as key vectors of WNV in Europe are printed bold (four species).So far there is no proof of any arbovirus transmission by mosquitoes in the British Isles, although antibodies to Sindbis, Tahyna, Usutu and West Nile viruses have been detected in British birds. Neighbouring European countries have enzootic WNV and human infections transmitted by mosquito species that are present in the British Isles. However, except for localized urban infestations ofCx. pipiensbiotypemolestusthat can be readily eliminated, there appear to be few situations in the British Isles where humans and livestock are exposed to sustained risks of exposure to potential WNV vectors. Monitoring of mosquitoes and arbovirus surveillance are required to guard the British Isles against WNV outbreaks and introduction of more anthropophilic mosquitoes such asStegomyia albopicta(Skuse) andOchlerotatus japonicus(Theobald) that have recently invaded Europe, since they transmit arboviruses elsewhere.
Fluorometric Detection of Histidine‐Tryptophan Complexes in Peptides and Proteins
Authors: Shinttzky M. , Goldman R. 
Published: March 2005

A study of the fluorescence properties of cyclo(l‐histidine‐l‐tryptophan), cyclo(l‐histidine‐d‐tryptophan), α,N‐acetyl‐l‐histidine‐l‐tryptophan methyl ester, α,N‐acetyl‐L‐histidine‐L‐tryptophan and (l‐histidine‐l‐tryptophan)3 has revealed an intramolecular interaction between the indole and the protonated imidazole side chains which results in marked quenching of the fluores‐cence intensity of the indole moiety. All five model compounds were found to possess a characteristic fluorometric titration curve which practically coincides with the potentiometric titration curve of the imidazole side chain of the histidine residue. Theoretical derivations of the pK from both titration curves are given. The extent of quenching by the protonated imidazole moiety, however, is different for each compound and varies from 40 to 80%.To detect the presence of intramolecular histidine‐tryptophan complexes in natural peptides and proteins, fluorometric titrations in aqueous solutions were carried out in the range of pH 4–9. Marked changes in fluorescence intensity with pH in the range of pH 5 to 8.5, suggesting the existence of well defined complexes, were observed with papain, activated papain, chymopapain, ficin and bromelain. Glucagon, pepsinogen, pepsin and goose egg white lysozyme show no change in fluorescence in this pH range. In systems where a histidine‐tryptophan interaction was observed, the pK value of the interacting histidine was evaluated from the fluorometric titration curve.
The Molecular Properties of the Methaemoglobin of Chironomus plumosus L. in Solution
Authors: Behlke J. , Scheler W. 
Published: March 2005

By means of an analytical ultracentrifuge the molecular weight of purified methaemoglobin from Chironomus plumosus has been determined at different pH values. Under weak acidic conditions (pH 5.2 to 7.0) the sedimentation constant amounts to 2.73 ± 0.02 S and the diffusion constant varies from 7.5 to 8.5 F. The molecular weight was calculated as 32,000 ± 1,500.
Outside of this pH‐range the molecular weight decreases. In alkaline solution (pH 9.2–10.0) the dimer molecule splits off reversibly into monomer subunits, with an average molecular weight of 14,600 ± 300.
In the pH‐range 7.5 to 9.0 and below 5.0 there exists a mixture of dimer and monomer molecules. The monomer‐dimer‐equilibrium is pH‐dependent. pH1/2 of this equilibrium coincides with the pH1/2 of the spectrophotometrically estimated main ionization constant (pH1/2= 8.3). The deprotonation of a haemin‐bound water molecule induces a change of the quarternary structure of the Chironomus‐methaemoglobin‐molecule.
According to the frictional ratio and the Stoke‐radius the monomer and the dimer MetHb‐molecules have an asymmetrical shape. Assuming a rotation ellipsoid (prolate type) for the monomer form (pH > 9.2) the axes are about 24 and 12.6 Å. The relatively high frictional ratio of the dimer molecule may be interpreted by an association of the α‐ and β‐monomers in direction of their longer axes.
On the Non‐Essentiality of Two Specific Disulphide Bonds in Ribonuclease for its Biological Activity
Authors: Neumann H. , Steinberg I. Z. , Brown J. R. , Goldberger R. F. , Sela M. 
Published: March 2005

The reaction of phosphorothioate with bovine pancreatic ribonuclease at pH 9.0 in the absence of urea led to a derivative, denoted 4PS‐ribonuclease, in which two of the four disulphide bonds in the molecule were opened. 4PS‐ribonuclease is a unique molecular species, and not a mixture of native and open‐chain ribonuclease; this is apparent from electrophoretic studies. By the use of the “diagonal map” technique it has been established unequivocally that the disulphide bonds opened were between half‐cystines 3–8 and 4–5, counting from the amino terminus along the ribonuclease chain.4PS‐ribonuclease is fully active enzymically toward RNA, and more active than the native enzyme toward cytidine 2′,3′‐cyclic phosphate. It is indistinguishable from native ribonuclease in its immunological reaction with antiserum to ribonuclease, and in its spectrophotometric titration, which shows that three of the six tyrosine phenolic groups in 4PS‐ribonuclease titrate abnormally. Unlike native ribonuclease, 4PS‐ribonuclease is digested by trypsin, even though at a lower rate than open‐chain ribonuclease.
Ferrochelatase Activity in Normal and Irradiated Animal Tissues
Authors: Goudy B. , Dawes E. , Wilkinson A. E. , Wills E. D. 
Published: March 2005

Ferrochelatase activity is present in rat and mouse liver, heart, kidney, spleen, bone marrow and intestinal mucosa. Enzyme activity is concentrated in the mitochondrial fraction and absent from the microsomal fraction. About 20% of the total activity of liver is in the 100,000 ×g supernatant.
Formation of lipid peroxides in mitochondria leads to some loss of enzyme activity but extensive lipid peroxidation can occur without substantial reduction in enzyme activity.
Ferrochelatase in tissue homogenates, mitochondria or in a purified form is unaffected by 50 kilorads in vitro but is 15%–30% inhibited after keeping irradiated samples for 20 h at 4°.
In liver, heart and muscle homogenates the activity of ferrochelatase, in mice irradiated with a whole body dose of 850 rads was not outside the range of control values; but in kidney, spleen, bone marrow and in liver and kidney mitochondria, there was an increase of enzyme activity on the 3rd day after irradiation, followed by a decrease and return to normal on the 9th–10th days.
It is considered unlikely that a decline in ferrochelatase activity can account for the accumulations of iron found in tissues of irradiated animals or that it is an important site of radiation damage in vivo.
l‐Glutamate‐Phenylpyruvate Aminotransferase
Authors: Scandurra R. , Cannella C. , Ferretti M. G. 
Published: March 2005

l‐glutamate‐phenylpyruvate aminotransferase was extracted from beef kidney mitochondria. The purification procedure included lysis of mitochondria in n‐butanol, ammonium sulphate fractionation between 55% and 80% saturation, gel filtration on G‐100 Sephadex and fractionation on DEAE‐Sephadex. The optimum pH of the enzyme is around 8. The enzyme is homogeneous to starch gel electrophoresis at various pH but shows two components when submitted to ultracentrifugal analyses.A possible dissociation of the enzyme into subunits dependent on concentration is discussed.
Amino Acid Sequence around Disulfide Bridge of Pig Immunoglobin λ‐Chains
Authors: Franěk F. , Keil B. , Nvotný J. , ŠOrm F. 
Published: March 2005

The λ‐chains of normal pig γG‐immunoglobulin were digested with pepsin in 1 M formic acid. Cystine‐containing peptides were isolated by gel filtration on Sephadex G‐25 and by chromatography on Dowex 50 and Dowex 1. The following structures were found:
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In addition to these peptides obtained in a high yield similar peptides were found but their complete structures were not determined in view of their low yield. The structures found in the λ‐chains display a high degree of similarity with corresponding structures known to exist in human Bence‐Jones proteins of the l‐type.
A Collagenolytic Enzyme from Aspergillus oryzae
Authors: Nordwig A. , Jahn W. F. 
Published: March 2005

A highly purified protease has been prepared from culture filtrates of Aspergillus oryzae. The process consists of four steps, namely the dialysis of the starting material, precipitation with acetone, separation by carrier‐free electrophoresis and fractionation with acetone. The specific activity of the protease is increased 40 times or more. The product was shown to be a single substance by means of the ultracentrifuge, disc electrophoresis and immuno‐electrophoresis. As far as investigated, it is free of non‐specific activities.
The molecular weight was found to be about 20,000 by elution from a Sephadex G‐75 column, by ultracentrifugation and by amino acid analysis. The pH optimum normally lies between 9 and 10. The protease cannot be activated with metal ions; it is, however, inhibited by Cu2+, Hg2+ and Zn2+ ions. It is also inhibited by di‐isopropyl phosphofluoridate and other compounds that react specifically with serine.
The protease splits denatured proteins preferentially, but not solely, at the peptide bonds of amino acids with acid side chains as shown by investigations on long‐chain model peptides. It also digests native collagen. The mode of splitting is the same as that by which the collagenase from Clostridium histolyticum splits the apolar regions. However, bonds involving hydroxyproline appear to be resistant to attack by the Aspergillus enzyme. In addition, the protease described here is capable of digesting bonds of the polar regions of the native collagen molecule. The protease also acts as an esterase.
On the basis of the various types of proteolytic specificity found for the protease a new concept is put forward for understanding collagen breakdown in vivo and in vitro.
Differences between the Reactivity of Endogenous and Exogenous Adenine Nucleotides in Mitochondria as Studied at Low Temperature
Authors: HELDT H. W. , KLINGENBERG M. 
Published: March 2005

The rates of phosphorylation of endogenous and exogenous ADP and of the uncoupler stimulated hydrolysis of endogenous and exogenous ATP by rat liver mitochondria have been measured at temperatures between 2–14°.1) The rate of the phosphorylation of endogenous ADP was found to be more than three times higher than the rate of the phosphorylation of exogenous ADP at 6°. The rates tend to approach each other at higher temperatures.2) The rate of the carbonylcyanide phenylhydrazone stimulated dephosphorylation of endogenous ATP was more than twenty times higher than that of exogenous ATP below 6°. Even at room temperature there remains a considerable difference between the two rates. Hence, it is concluded that only the hydrolysis of endogenous ATP can be taken as a measure of the activity of mitochondrial ATPase. At low temperatures ATPase was not stimulated by dinitrophenol, and dinitrophenol caused an inhibition of carbonylcyanide phenylhydrazone stimulated ATPase.3) Atractyloside inhibited only the reactivity of exogenous ADP and ATP, but had no influence on the rate of phosphorylation of endogenous ADP or the rate of carbonylcyanide phenylhydrazone stimulated hydrolysis of endogenous ATP.4) In principle the same results were obtained with rat heart mitochondria, where the difference in the rate of reactivity of endogenous and exogenous adenine nucleotides was considerably smaller than in rat liver mitochondria.It is concluded that the access of exogenous adenine nucleotides to the inner compartment of the mitochondria, where the endogenous adenine nucleotides are located and where oxidative phosphorylation takes place, is limited at low temperature by the adenine nucleotide translocation.
Bromthymol Blue as a pH Indicator in Mitochondrial Suspensions
Authors: MITCHELL P. , MOYLE J. , SMITH L. 
Published: March 2005

The distribution of the functional group of the pH indicator bromthymol blue across the osmotic barrier component (or M phase) of the cristae membrane separating the inner from the outer aqueous phase of rat liver mitochondria has been measured by three partially independent methods. In mitochondria in State 5, under the usual conditions, only about one third of the total bromthymol blue reacts in the inner phase. In State 3, in presence of a high concentration of valinomycin in a KCI medium, approximately the same proportion of the bromthymol blue reacts in the inner phase as in State 5; but in State 4, practically all the bromthymol blue is expelled across the M phase and registers the pH of the outer phase.The bromthymol blue technique is incompetent to measure the pH of the inner phase of mitochondria in State 4; but a method is described that will permit the approximate quantitative measurement of the intramitochondrial pH from the light extinction of bromthymol blue in State 5 (or in State 3 in presence of valinomycin) provided that the distribution of the indicator and the internal and external buffering powers of the mitochondrial suspension are known.The expulsion of the bromthymol blue from the mitochondria in State 4 is attributable to the development of an electric potential across the M phase.
The Action of Phospholipase A on the Plasma Membranes of Rat Liver Cells
Authors: GALLAI‐HATCHARD J. , GRAY G. M. 
Published: March 2005

Isolated liver cells were treated with snake venom phospholipase A to obtain information on the relative importance of different phospholipids in the plasma membrane to its structural stability.
The hydrolysis of phosphatidylethanolamine and lecithin by phospholipase A from Naia naia produced a change in the permeability of the liver cell plasma membrane which was arbitrarily assessed by measuring the amount of the intracellular enzyme glutamic oxaloacetic transaminase released into the incubation medium.
There was only a small leakage of glutamic oxaloacetic transaminase from the cell until 25–35% of the phosphatidylethanolamine had been hydrolysed. Further hydrolysis caused a rapid increase in the release of the enzyme. Very little lecithin was hydrolysed by the same enzyme concentrations.
After treatment with phospholipase A the cells were stained with either acridine orange, eosin or nigrosin and examined by light, phase contrast and fluorescent microscopy. Their gross morphology appeared to be unaltered by the hydrolysis of up to 50–60% of the cell phosphatidylethanolamine.
The results suggest that phosphatidylethanolamine is relatively more important than lecithin in maintaining, in terms of permeability to a protein molecule, the structural integrity of the liver cell plasma membrane.