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T Barrett

Publications and source records attributed to T Barrett.

At least 109 records · Page 6Linked to original sources
PubMed1996

Ethanol ingestion inhibits cell-mediated immune responses of unprimed T-cell receptor transgenic mice.

This paper introduces a transgenic (Tg) mouse in which the majority of the CD4-bearing T cells have T-cell receptors that react with ovalbumin (OVA) as a model for ethanol research. Although these Tg animals were bred onto the BALB/c genetic background, a strain generally considered to be nonpreferring in ethanol consumption, we determined that BALB/c mice would consume an ethanol-containing liquid diet, without significant mortality, and assessed alteration of specific immune responses. BALB/c, C57BL/6 (B6), or (BALB/c x C57BL/6)F-1 hybrid (CB6F1) mice were fed LED containing 35, 30, 25, or 20% ethanol-derived calories. Significant mortality (> 40%) was seen only in BALB/c and pronounced weight loss was seen in BALB/c, B6, CB6F1 mice when they were fed the diet containing the greatest ethanol concentration (LED35). Diets containing lesser amounts of ethanol did not cause mortality. Liquid diets containing > or = 30% ethanol-derived calories significantly impaired the chicken gamma-globulin-specific delayed hypersensitivity responses in BALB/c, B6, and CB6F1mice without significantly affecting the humoral immune response to sheep red blood cells. We show that immunization of the Tg mice is not required for the development of a vigorous "delayed hypersensitivity" response to OVA or the I-Ad-restricted peptide OVA323-339 in mice fed standard solid lab chow or liquid control diet. In marked contrast, OVA Tg mice fed ethanol show a profound inhibition of this immune response, indicating that ethanol-induced inhibition of cell-mediated immunity occurs independently of antigen priming.

Alcoholism↗
PubMed1996

MKK3- and MKK6-regulated gene expression is mediated by the p38 mitogen-activated protein kinase signal transduction pathway.

The p38 mitogen-activated protein (MAP) kinase signal transduction pathway is activated by proinflammatory cytokines and environmental stress. The detection of p38 MAP kinase in the nucleus of activated cells suggests that p38 MAP kinase can mediate signaling to the nucleus. To test this hypothesis, we constructed expression vectors for activated MKK3 and MKK6, two MAP kinase kinases that phosphorylate and activate p38 MAP kinase. Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. Cotransfection experiments demonstrated that p38 MAP kinase activation causes increased reporter gene expression mediated by the transcription factors ATF2 and Elk-1. These data demonstrate that the nucleus is one target of the p38 MAP kinase signal transduction pathway.

Amino Acid Sequence↗
PubMed1995

The crystal structure of a cyanogenic beta-glucosidase from white clover, a family 1 glycosyl hydrolase.

BACKGROUND: beta-glucosidases occur in a variety of organisms and catalyze the hydrolysis of aryl and alkyl-beta-D-glucosides as well as glucosides with only a carbohydrate moiety (such as cellobiose). The cyanogenic beta-glucosidase from white clover (subsequently referred to as CBG) is responsible for the cleavage of cyanoglucosides. Both CBG and the cyanoglucosides occur within the plant cell wall where they are found in separate compartments and only come into contact when the leaf tissue experiences mechanical damage. This results in the eventual production of hydrogen cyanide which acts as a deterrent to grazing animals. beta-glucosidases have been assigned to particular glycosyl hydrolase families on the basis of sequence similarity; this classification has placed CBG in family 1 (there are a total of over 40 families) for which a three-dimensional structure has so far not been determined. This is the first report of the three-dimensional structure of a glycosyl hydrolase from family 1. RESULTS: The crystal structure of CBG has been determined using multiple isomorphous replacement. The final model has been refined at 2.15 A resolution to an R factor of 18.9%. The overall fold of the molecule is a (beta/alpha)8 [or (alpha/beta)8] barrel (in common with a number of glycosyl hydrolases) with all residues located in a single domain. CONCLUSIONS: Sequence comparisons between beta-glucosidases of the same family show that residues Glu183 and Glu397 are highly conserved. Both residues are positioned at the end of a pocket located at the C terminus of the barrel and have been assigned the respective roles of proton donor and nucleophile on the basis of inhibitor-binding and mutagenesis experiments. These roles are consistent with the environments of the two residues. The pocket itself is typical of a sugar-binding site as it contains a number of charged, aromatic and polar groups. In support of this role, we present crystallographic data on a possible product complex between CBG and glucose, resulting from co-crystallization of the native enzyme with its natural substrate, linamarin.

Binding Sites↗
PubMed1995

Hemolytically inactive C5b67 complex: an agonist of polymorphonuclear leukocytes.

The activity of hemolytically inactive C5b67, designated iC5b67, was evaluated as an agonist for functional responses of human polymorphonuclear leukocytes (PMN). C5b67 was formed from purified human complement components and decayed in phosphate-buffered saline (PBS) until it had no lytic activity for sheep erythrocytes in a standard assay. iC5b67, at nanomolar concentrations, stimulated PMN chemotaxis and Ca2+ fluxes, but inhibited superoxide production and failed to upregulate CR1 and CR3. There was no significant contamination of the iC5b67 with C5a to explain these results. Neither isolated C5b6 nor C7 alone exhibited the activities of iC5b67, while insolubilized anti-C7 could remove the PMN agonist activity from the iC5b67 preparation. Binding studies to define a specific receptor for iC5b67 on PMN were hampered by the very hydrophobic nature of the ligand. 125I-iC5b67, by contrast to hemolytically active 125I-C5b67, was unable to insert in erythrocytes, suggesting that iC5b67 need not insert in the PMN membrane to induce signaling. Two lines of evidence suggest that iC5b67 and C5a and FMLP share common steps in intracellular signaling (1) pretreatment of PMN with iC5b67 deactivates PMN for C5a- and FMLP-induced chemotaxis; and (2) pretreatment of PMN with pertussis toxin inhibits iC5b67-induced chemotaxis. Thus, iC5b67 has important effects on the activity of PMN and G-proteins and Ca2+ are involved in the signaling.

Chemotaxis, Leukocyte↗
PubMed1995

Independent human MAP-kinase signal transduction pathways defined by MEK and MKK isoforms.

Mammalian mitogen-activated protein (MAP) kinases include extracellular signal-regulated protein kinase (ERK), c-Jun amino-terminal kinase (JNK), and p38 subgroups. These MAP kinase isoforms are activated by dual phosphorylation on threonine and tyrosine. Two human MAP kinase kinases (MKK3 and MKK4) were cloned that phosphorylate and activate p38 MAP kinase. These MKK isoforms did not activate the ERK subgroup of MAP kinases, but MKK4 did activate JNK. These data demonstrate that the activators of p38 (MKK3 and MKK4), JNK (MKK4), and ERK (MEK1 and MEK2) define independent MAP kinase signal transduction pathways.

Amino Acid Sequence↗
PubMed1995

Typhoid fever in the park: epidemiology of an outbreak at a cultural interface.

The number of reported outbreaks of typhoid fever in the United States has recently increased. Only six were reported from 1980-1989, but seven outbreaks were reported in 1990. In August 1990, health officials in Montgomery County, Maryland, were notified of two cases of typhoid fever among persons who had attended both a family picnic attended by 60 persons and a Latin Food Festival attended by 100,000 people. We obtained interviews, blood and stool cultures, and Vi serologies from attendees at and food handlers for the picnic. We defined cases as culture-confirmed or probable. Of the 60 picnic attendees, 24 (40%) had cases, of which 16 were culture confirmed. Those who ate potato salad were at increased risk of disease (17/32 vs. 6/28, relative risk [RR] = 2.5, 95% confidence interval [CI] 1.1-5.4). Picnic attendees who also attended the Latin Food Festival were not at significantly greater risk of disease than those who did not, (11/22 vs. 13/38, RR = 1.5, CI = 0.8-2.7) and we found no evidence of disease among other festival attendees. The potato salad was prepared with intensive handling and without adequate temperature control by a recent immigrant from El Salvador who was asymptomatic, did not attend the picnic, had Salmonella typhi (S. typhi) in her stool, and had elevated Vi antibodies, strongly suggestive of the carrier state. Outbreaks of typhoid fever are a threat for cosmopolitan communities. While currently available control measures are unlikely to prevent all outbreaks, thorough investigation can identify previously unrecognized carriers.

Adolescent↗
PubMed1995

Evaluation of polymerase chain reaction for the detection and characterisation of rinderpest and peste des petits ruminants viruses for epidemiological studies.

The high sequence variability found in RNA viruses makes it difficult to design primers for reverse transcription-polymerase chain reaction amplification which will be certain to work with all new field isolates. To overcome this problem for the detection and differential diagnosis of rinderpest (RP) and peste des petits ruminants (PPR) viruses (V), we have designed several sets of primers, based on well-conserved sequences in the P and F genes. Analysis of a large number of field isolates from every region of the world where RPV and PPRV are found showed that no sample failed to react with more than one of the primer sets. To facilitate the multiple analyses, the reverse transcription step was performed using random hexanucleotide primers and aliquots of the cDNA were then amplified using a panel of primer sets to identify and differentiate between the virus nucleic acids in the samples. Evaluation of the method was carried out using eye swabs collected from cattle experimentally infected with RPV and goats infected with PPRV during the course of vaccine trials and on field samples such as whole blood, mouth swabs, lung, spleen and other tissues submitted to the laboratory for diagnosis. Sequencing the PCR products enabled us to examine the genetic relationships between new and previous field isolates from different geographical areas.

Animals↗
PubMed1995

Phylogenetic evidence of canine distemper virus in Serengeti's lions.

Recently an epizootic, reported to be due to a morbillivirus infection, affected the lion population of the Tanzanian Serengeti National Park. A morbillivirus phosphoprotein (P) gene fragment was amplified by PCR from tissue samples of several affected lions. Sequencing of the amplificates and subsequent phylogenetic analyses revealed that a wild-type strain of canine distemper morbillivirus (CDV) was involved. Vaccination of the local domestic dog population with proven safe CDV vaccines is proposed.

Animals↗
PubMed1995

Protection of goats against peste des petits ruminants with recombinant capripoxviruses expressing the fusion and haemagglutinin protein genes of rinderpest virus.

Goats were protected against a lethal challenge of peste des petits ruminants (PPR) virus following vaccination with a recombinant capripoxvirus containing either the fusion (F) gene of rinderpest virus or the haemagglutinin (H) gene of rinderpest virus. The H gene recombinant produced high titres of neutralizing antibody to rinderpest virus in the vaccinated goats, whereas the F gene recombinant failed to stimulate detectable levels of neutralizing antibody. A similar response to the two recombinant vaccines has previously been reported for cattle. Neither recombinant produced detectable levels of specific antibodies to PPR virus.

Animals↗
PubMed1995

Pathomorphological and immunohistological findings in cattle experimentally infected with rinderpest virus isolates of different pathogenicity.

Experimental infection of nine cattle with seven rinderpest virus strains of different pathogenicity resulted in significant variations of clinical signs, morphological lesions and distribution of viral antigen in tissues. The severity of clinical disease was correlated with the extent of tissue alterations and the amount of immunohistologically detectable viral antigen. Both mild and virulent strains of rinderpest share essentially the same tissue tropisms in vivo, i.e. epithelio- and lympho-tropism. However, rinderpest virus isolates of higher pathogenicity showed a more rapid and wider distribution with more extensive lesions than milder strains, which probably accounts for the higher mortality.

Animals↗
PubMed1995

Characterisation of African isolates of rinderpest virus.

Isolates of rinderpest virus (RPV) recovered from outbreaks of the disease in Kenya and Southern Sudan between 1986 and 1993 were compared to each other and to earlier isolates from East and West Africa. The recent isolates were mildly pathogenic for susceptible cattle and thus resembled other mild strains of RPV recovered from cattle and wildlife in East Africa more than 30 years ago. Monoclonal antibody analysis using a panel of 12 anti-RPV haemagglutinin protein-specific antibodies (mAbs) revealed that individual isolates were distinguishable. However, the panel of mAbs could not be used to relate the isolates on the basis of their pathogenicity or geographic origin. Immunoprecipitation of the virus-induced proteins from infected Vero cells, followed by SDS-polyacrylamide gel electrophoresis, showed that the recent mild RPV isolates from eastern Africa were closely related to each other and to their contemporary isolates from Nigeria and Egypt, but they were distinct from another mild isolate recovered from the region three decades ago. Two distinct lineages of African RPV isolates were identified by sequencing a region of the genome around the proteolytic enzyme cleavage site of the fusion protein from the old and new isolates. One lineage, which included virus isolates recovered from East and West Africa during the 1960s, showed a closer phylogenetic relationship to Asian and Middle Eastern RPV isolates. The other lineage consisted mainly of isolates recovered from East, West and North Africa between 1983 and 1993. The results showed that there was co-circulation of two different lineages of RPV in Nigeria during the epizootics of the 1980s.

Africa↗
PubMed1995

The sequence of the N and L genes of rinderpest virus, and the 5' and 3' extra-genic sequences: the completion of the genome sequence of the virus.

We have sequenced the nucleocapsid (N) and polymerase (L) genes of the vaccine strain of rinderpest, and the 5' and 3' terminal domains of the genome. Together with previously published data, this completes the sequence of the entire genome of rinderpest virus. The L gene is identical in length to that of measles virus, encoding a 2183 amino acid protein with a calculated molecular weight of 248,100. The L protein sequence of three morbilliviruses is highly conserved, greater than 76% of residues being identical or conserved in all sequences. The N protein was, as for other sequenced genes, essentially identical to that of the virulent parent. The viral genome is 15,881 bases in length, similar to that of measles virus and slightly longer than that of canine distemper virus. The terminal sequences of the genome and those at the gene boundaries were compared to the analogous regions of other morbilliviruses and representatives of related groups of paramyxoviruses.

Amino Acid Sequence↗
PubMed1995

Morbillivirus infections of aquatic mammals: newly identified members of the genus.

Several disease outbreaks, which have caused the deaths of many thousands of seals and dolphins during the last decade, have now been attributed to infections with newly identified Morbilliviruses. Outbreaks in the late eighties amongst harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) in northwestern Europe and amongst baikal seals (Phoca sibirica) in Siberia were caused by the newly discovered phocine distemper virus and by a strain of canine distemper virus, respectively. Although closely related these two viruses were not identical. They were more distantly related to the viruses which caused mass mortality amongst striped dolphins (Stenella coeruleoalba) in the Mediterranean sea in the early nineties. This dolphin morbillivirus was shown to be closely related to a virus that was found in harbour porpoises (Phocoena phocoena) which had stranded at the coasts of northwestern Europe in the late eighties: porpoise morbillivirus. The present knowledge of the genetic and antigenic relationships of these apparently new members of the genus Morbillivirus with the established members of the genus is presented. In addition, the origin and epizootiological aspects of these newly discovered viruses are discussed. Finally experimental evidence that environmental pollution may have contributed to the severity and extent of these infections in recent years is presented.

Animals↗
PubMed1995

Morbilliviruses in aquatic mammals: report on round table discussion.

A workshop was organised to ascertain the current situation with regard to morbillivirus infections in aquatic animals. The great interest generated by the discovery of these new virus infections in 1988 has to some extent abated but much high quality research has continued in this field as the workshop showed. There is some serological evidence that the viruses have continued to circulate in most areas since the initial epizootics. As to their origin, it appears that the most likely source of the European seal morbillivirus (PDV-1) is the North Atlantic and Artic seal populations. As to the origin of the Mediterranean dolphin morbillivirus and the morbilliviruses isolated from porpoises, there is serological evidence that the viruses are widespread in many cetacean species in the Atlantic and 93% of long-finned pilot whales (Globicephala melas) which mass stranded between 1982 and 1993 were morbillivirus seropositive. The epizootic in freshwater seals in Lake Baikal was unrelated to events in the European marine mammal populations. The virus which infected these animals (PDV-2) is indistinguishable from canine distemper field strains. Serological and molecular biological studies provided evidence for the presence of the virus in the seals, at least as late as the Summer of 1992 when the animals were last sampled.

Animals↗
PubMed1995

Editing of morbillivirus P gene transcripts in infected animals.

RNA editing in the Morbillivirus genus in vivo was investigated by applying a polymerase chain reaction-based primer extension technique to measure the edited and non-edited mRNA transcripts. In this genus of the Paramyxoviridae the P gene transcript is altered by the co-transcriptional addition of one extra G residue to produce the mRNA for the V non-structural protein. Using tissues of phocine distemper virus (PDV) infected seals, canine distemper virus (CDV) infected dogs and rinderpest virus (RPV) infected cattle, it was demonstrated that editing occurs in vivo. The P:V mRNA ratios were generally similar to those found in tissue culture infections with the same virus and a minor fraction of transcripts had 2-4 extra G residues. In one seal brain infected with PDV the ratio of P:V mRNA was reversed but no differences were found in the levels of mRNA editing in different tissues from the same animal infected with CDV or RPV. However, variation was seen between animals infected with different isolates of RPV and even between animals infected with the same isolate of RPV.

Animals↗
PubMed1995

A comparison of two starting doses of human menopausal gonadotrophin for follicle stimulation in unselected patients for in-vitro fertilization.

Ovarian responses and embryology data were compared in patients undergoing in-vitro fertilization following follicular stimulation using long course gonadotrophin-releasing hormone (GnRH) analogue/human menopausal gonadotrophin (HMG) in which the initial daily dose was two (150 IU) or three ampoules (225 IU) maintained for a minimum of 7 days. Group 1 (n = 31; centre A) patients were treated with a starting dose of two ampoules, while group 2 (n = 46; centre A) patients were treated chronologically immediately before group 1 with a starting dose of three ampoules per day. Group 3 (n = 74; centre B) patients were treated with three ampoules per day simultaneously with group 1. There was no difference in the distributions of patient ages or reasons for treatment between the three groups. Group 1 required longer treatment before the plasma oestradiol attained 250 pg/ml than did both the other groups (group 1, 9.0; group 2, 6.9; group 3, 6.7 days; P < 0.01), and this resulted in a longer follicular phase for group 1 (mean: 14.5 days compared with 12.7 and 12.8 for groups 2 and 3 respectively; P < 0.05). The numbers of follicles > 16 mm in diameter at human chorionic gonadotrophin (HCG) administration and the numbers of eggs and embryos were all significantly lower (P < 0.04) in group 1, and cycle cancellations due to insufficient ovarian responses were higher (P < 0.02) in group 1. There was no difference in the numbers of ampoules used, the oestradiol concentration at HCG, the fertilization and pregnancy rates or the incidence of hyperstimulation syndrome in the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Sequencing and analysis of the nucleocapsid (N) and polymerase (L) genes and the terminal extragenic domains of the vaccine strain of rinderpest virus.

The nucleocapsid (N) and polymerase (L) genes of the vaccine strain of rinderpest, and the 5' and 3' terminal domains of the genome have been sequenced. Together with previously published data, this completes the sequence of the entire genome of rinderpest virus. The viral genome is 15,881 bases in length, similar to that of measles virus and slightly longer than that of canine distemper virus. The L gene is identical in length to that of measles virus, encoding a 2183 amino acid protein with a calculated M(r) of 248,100. The L protein sequence of morbilliviruses is highly conserved, more than 75% of residues being identical or conserved in all three sequences currently available. The N protein was, as for the other sequenced genes where comparison is possible, essentially identical to that of the virulent parent. In addition, we have determined the terminal sequences of two virulent strains of rinderpest and compared the sequences of virulent and non-virulent strains.

Amino Acid Sequence↗