Molecular and cell biology of opportunistic infections in AIDS. Salmonella, Shigella and Campylobacter.
Explore the source record for details and available documents.
AIDS-Related Opportunistic Infections↗
Biomedical subjects
R L Warren
Publications and source records attributed to R L Warren.
Acute traumatic disruption of the thoracic aorta: emergency department management.
STUDY OBJECTIVE: To evaluate the safety and effectiveness of temporary IV antihypertensive therapy in patients with acute traumatic thoracic aortic disruption. DESIGN: Retrospective chart review of all patients treated for proven traumatic aortic disruption during the ten-year period of 1980 through 1989. SETTING: Emergency department of a large, urban, Level I trauma center. INTERVENTIONS: Preoperative IV beta-blockade and nitroprusside after initial resuscitation in hemodynamically stable patients. RESULTS: Thirty-seven patients with angiographically proven aortic disruption were separated retrospectively into one of three groups. Group 1 (15 patients without preoperative antihypertensive therapy) had two deaths. Group 2 (15 patients treated for two to seven hours [mean, 3.8 hours] before surgery with antihypertensives) had one death. Group 3 (seven patients treated with antihypertensives for 24 hours to four months before surgery to allow recovery from associated severe injuries) had one death. There were no complications resulting from antihypertensive therapy. CONCLUSION: Temporary antihypertensive therapy appears to be safe and effective in patients with aortic disruption.
Adolescent↗
The K1 capsule is the critical determinant in the development of Escherichia coli meningitis in the rat.
Although Escherichia coli strains possessing the K1 capsule are predominant among isolates from neonatal E. coli meningitis and most of these K1 isolates are associated with a limited number of 0 lipopolysaccharide (LPS) types, the basis of this association of K1 and certain 0 antigens with neonatal E. coli meningitis is not clear. The present study examined in experimental E. coli bacteremia and meningitis in newborn and adult rats whether or not the K1 capsule and/or O-LPS antigen are critical determinants in the development of meningitis. Rats received subcutaneously at K1 E. coli strain (018+K1+) or mutants lacking either the K1 capsule (018+K1-) or 0 side-chain (018-K1+). 12-24 h later, blood and cerebrospinal fluid (CSF) specimens were obtained for quantitative cultures. The isolation of E. coli from CSF was observed in both newborn and adult rats infected with K1+ strains regardless of LPS phenotype (018+ or 18-) who also developed a high degree of bacteremia (e.g., greater than 10(4) CFU/ml of blood). In contrast, none of the newborn and adult rats infected with 018+K1- and developing bacteremia of greater than 10(4) were found to have positive CSF cultures. These findings indicate that the presence of the K1 capsule and a high degree of bacteremia are key determinants in the development of E. coli meningitis, suggesting that there may be specific binding sites present in the brain which have an affinity for the K1 capsule and thus may be responsible for the entry of K1-encapsulated E. coli into the meninges.
Animals↗
Tn5 mutagenesis of the Salmonella typhimurium 100 kb plasmid: definition of new virulence regions.
In this study, the 100 kb plasmid of Salmonella typhimurium, which is known to contribute to the pathogenicity of the organism, was tagged with the transposon Tn5 to define regions of the plasmid contributing to overall virulence. Eleven randomly selected vir::Tn5 plasmids carried by the plasmid-free S. typhimurium strain WS1321 were physically mapped and then examined in mice for subcutaneous LD50 value, ability to induce splenomegaly, and ability to grow to high numbers in the spleens of infected mice. Nine strains were found to be virulence-attenuated and showed varied levels of growth in the spleens of subcutaneously infected BALB/c mice. Eight of these nine strains carried Tn5 insertions which lie outside the previously defined virulence region. These studies corroborate the findings of other investigators as well as defining novel regions of the 100 kb virulence plasmid involved in the pathogenicity of this organism.
Animals↗
Effects of FP2 and a mercury resistance plasmid from Pseudomonas aeruginosa PA103 on exoenzyme production.
Plasmids encoding mercury resistance carried by Pseudomonas aeruginosa PAO1161 and PA103 were found to be involved in regulating the secretion of protease, phospholipase C, and alkaline phosphatase. Previously, mutations in Pseudomonas strains that caused pleiotropic effects on the production of extracellular enzymes were mapped to the bacterial chromosome. We show that pleiotropic changes in extracellular enzyme production can also be regulated by plasmids. In this study, the effects on secretion of exoenzymes by two mercury resistance plasmids, FP2 from PAO1161 and pRLW103 from PA103, were assayed in P. aeruginosa PAO1 and PAO18. The introduction of either plasmid into PAO1 resulted in a significant decrease in exoprotease production. Additionally, pRLW103 significantly increased the production of alkaline phosphatase by both strains. Phospholipase C was produced only in strain PAO18 containing the pRLW103 plasmid. FP2 had no effect on alkaline phosphatase or phospholipase C production in either strain and was found to decrease exoprotease secretion only in strain PAO1. The results indicate the P. aeruginosa mercury resistance plasmids vary in their ability to modify exoenzyme expression, and this ability is influenced by the host strain.
Alkaline Phosphatase↗
Method for identifying microbial antigens that stimulate specific lymphocyte responses: application to Salmonella.
Vaccine development and understanding of cellular immune stimulatory mechanisms have been impeded by the paucity of data on microbial antigens that stimulate protective immunity. We describe here a general method for identifying and isolating peptide antigens that specifically stimulate sensitized lymphocytes. First, Salmonella typhimurium C5 genomic DNA fragments were subcloned into Escherichia coli by use of the lambda gt11 expression vector. Next, antigens expressed by recombinant phage from this genomic library were tested for their capacity to stimulate proliferative responses in pooled lymphocytes obtained from BALB/c mice infected 14 days earlier with S. typhimurium. Of 2000 recombinant phages tested, 5 stimulated a polypeptide-antigen-specific proliferative response. Physical analyses of these 5 recombinant phages revealed cloned inserts of 0.5-2.4 kilobase pairs representing nonoverlapping regions of the C5 chromosome. Four of the five insert DNAs hybridized at high stringency to both S. typhimurium and Salmonella typhi total chromosomal DNA, suggesting that these pathogens of different host specificity share several antigenic determinants. Use of sensitized primary polyclonal lymphocytes provides a rapid and simple method for screening recombinant DNA libraries for clones that stimulate specific immune responses and avoids the use of cloned lymphocyte cell lines. This approach should be generally applicable to similar studies in different hosts of many other microbial pathogens.
Animals↗
Detection of restriction fragment length polymorphisms in clinical isolates and serially passaged Pseudomonas aeruginosa strains.
An 800-base-pair HindIII-PstI fragment that flanks a hot spot for Tn7 insertion was isolated from the chromosome of Pseudomonas aeruginosa and cloned into pUC12. The fragment was used to probe XhoI digests of genomic DNA from 18 P. aeruginosa isolates collected from sputum samples of seven cystic fibrosis patients. Only two XhoI restriction fragment length polymorphisms (RFLPs), of 3.7 and 7.7 kilobases (kb), were detected. Isolate WSU3531-1 (3.7-kb XhoI fragment) and WSU3860 (7.7-kb XhoI fragment), while isolated from the same patient, showed different RFLPs. Serial passages of isolate WSU3531-1 demonstrated that this strain was phenotypically stable. In contrast, colony and pigment variants were readily isolated at a frequency of 1% from serial passages of isolate WSU3860. When XhoI-digested genomic DNA from phenotypic variants of serially passaged WSU3860 were probed with the 800-base-pair HindIII-PstI fragment, the probe hybridized to a 10.4-kb XhoI fragment from three isolates. Restriction analysis of the genomic DNA digested with a variety of restriction enzymes showed that a 2.7-kb insertion occurred in the same region for all three isolates. There appeared to be no correlation between changes in the RFLP and changes in colony morphology.
DNA Probes↗
Novel virulence properties of the Salmonella typhimurium virulence-associated plasmid: immune suppression and stimulation of splenomegaly.
Mice infected subcutaneously with wild-type Salmonella typhimurium, SR11, developed a significant splenomegaly when compared with mice infected with an equal number of a plasmid-cured strain. Further, the bacterial load in the spleen at 14 days after infection, measured as colony-forming units per gram tissue, was significantly higher in mice infected with the parent strain than in mice infected with the plasmid-cured strain. These data confirm the previously reported plasmid-associated ability of Salmonella to multiply within the spleen. In addition, lymph node cells (LNC) from mice infected with the parent strain had a significantly reduced ability to proliferate in response to concanavalin A, a T-cell mitogen, and to heat-killed S. typhimurium cells when compared with LNC isolated from mice infected with the plasmid-cured strain. Finally, reintroduction of a functional Tn5-tagged 90-kb plasmid into a plasmid-free strain restored its capacity to cause a marked splenomegaly and to suppress lymph node cell proliferation in BALB/c mice. These data demonstrate that the 90-kb plasmid of highly virulent S. typhimurium strains mediates several novel pathogenic properties in infected mice: (1) enhancement of the ability of Salmonella to multiply within the spleen; (2) stimulation of a splenic inflammatory response as displayed by marked splenomegaly; and (3) a general suppression of lymphocyte responsiveness to both T-cell mitogens and specific Salmonella antigens.
Animals↗
Localization of callosal auditory pathways: a CT case study.
The position of the auditory pathways in the human corpus callosum has not been defined by modern imaging techniques. We report a case with a discrete hemorrhagic lesion in the posterior body of the corpus callosum. The only signs of disturbed callosal function were limited to the auditory system--suppression of left ear stimuli with dichotic listening and neglect of left-sided auditory simultaneous stimuli.
Adult↗
Lithium inhibits morphogenesis of the nervous system but not neuronal differentiation in Xenopus laevis.
Xenopus embryos treated with 100 mM-lithium from the 2- to 4-cell stage to the early blastula stage (4h) failed to neurulate and developed without a discernible anteroposterior axis. The internal structure of defective embryos was grossly disorganized, but immunohistochemical staining with cell-type-specific antibodies revealed differentiated nerve and muscle cells. Quantitative assay in tissue cultures from control and acutely abnormal lithium-treated embryos showed that neural differentiation was enhanced and muscle differentiation unaffected. The embryos took up about 0.5 mM-lithium at threshold, maximal effects resulted at 2-3 mM. Most of the lithium was extruded from the cells into the blastocoel fluid, where lithium reached 17 mM. The threshold intracellular concentration was about 150 microM. Lithium uptake rose steeply as the osmotic/ionic strength of the bathing medium increased. Sodium, potassium and lithium were equally able to increase the permeability of the embryo. However, sodium ions enhanced, while potassium ions interfered with, the uptake of lithium. Treatment with lithium at progressively later stages reduced the developmental defects and neural differentiation returned to normal levels. The uptake of lithium did not decline concomitantly. We conclude that lithium does not inhibit neural induction, but interferes with dorsal patterning. The sensitivity of the embryo to lithium is determined by developmental stage. The very low, effective intracellular concentrations may be important in understanding the mechanism of lithium-generated defects.
Animals↗
A case of thalamic aphasia with postmortem verification.
This study discusses a case of aphasia after dominant thalamic lesion, a hemorrhagic infarction. Unlike other such cases, both repeated standardized assessment and postmortem verification were available. The patient was assessed at 3 weeks and again at 9 weeks postonset. The aphasia demonstrated the syndrome common to dominant thalamic hemorrhage: fluent but paraphasic output sometimes deteriorating to jargon, comprehension less impaired than this type of output usually indicates, and the least impairment in repetition. As sometimes reported in previous cases, semantic paraphasias were more common than phonemic paraphasias. The lesion was located in the dorsal aspect of the lateral nucleus, but it extended into the pulvinar, including the anterior superior lateral aspect which has been implicated in language by previous studies. Thus, data from this case are consistent with an involvement of the dominant pulvinar in language and suggest that this role involves the semantic aspects of language.
Aged↗
Acute alveolar hypoxia increases bronchopulmonary shunt flow in the dog.
To study the effects of alveolar hypoxia on canine bronchopulmonary shunt flow, a biventricular bypass preparation was employed. The preparation allowed a constant and sensitive measure of changes in pulmonary venous blood flow. In 16 of 18 dogs with intact bronchial arteries, alveolar hypoxia caused an increase in pulmonary venous return both under conditions of constant pulmonary arterial inflow and under conditions of no pulmonary arterial inflow, suggesting bronchopulmonary shunting. This effect was accompanied by systemic vasodilation despite vagotomy and ganglionic blockade, and was abolished by division of all bronchial vessels. Ibuprofen, 3 mg/kg, and indomethacin, 15 mg/kg, in dogs with intact bronchial vessels, abolished both the increase in pulmonary venous return and the systemic vasodilatation caused by hypoxia. Thus, alveolar hypoxia directly augments bronchopulmonary flow, most likely through release of one or more vasodilating prostaglandins.
Animals↗
Selective inhibition of the accumulation of extracellular proteases of Pseudomonas aeruginosa by gentamicin and tobramycin.
Gentamicin and tobramycin inhibited the accumulation of extracellular proteases secreted by Pseudomonas aeruginosa. The secretion of protease was inhibited at concentrations of these drugs that were below the level required to inhibit general protein synthesis. Neither magnesium ions nor high ionic strength antagonized the ability of the aminoglycosides to block secretion of the proteases. Under these culture conditions magnesium ions were shown to antagonize the effects of the aminoglycosides on protein synthesis and aminoglycoside-mediated lysozyme lysis of P. aeruginosa. These results suggested that the drugs blocked secretion of the proteases by acting at the level of the outer membrane.
Culture Media↗
Transposon mutagenesis of Pseudomonas aeruginosa exoprotease genes.
Transposon Tn5 was used to generate protease-deficient insertion mutants of Pseudomonas aeruginosa. The presence of Tn5 in the chromosome of P. aeruginosa was demonstrated by transduction and DNA-DNA hybridization. The altered protease production and kanamycin resistance were cotransduced into a wild-type P. aeruginosa strain. A radiolabeled probe of Tn5 DNA hybridized to specific BamHI fragments isolated from the insertion mutants. Two independently isolated Tn5 insertion mutants had reduced protease production, partially impaired elastase activity, and no immunologically reactive alkaline protease.
Conjugation, Genetic↗
Protease phenotypes of Pseudomonas aeruginosa isolated from patients with cystic fibrosis.
The protease phenotypes expressed by isolates of Pseudomonas aeruginosa from cystic fibrosis (CF) patients were evaluated. The majority of isolates tested produced elastase (65%) or alkaline protease (64%) or both. The mucoid phenotype expressed by many CF isolates of P. aeruginosa did not absolutely restrict the expression of protease activity, although a higher percentage of nonmucoid isolates was proteolytic. When isolates from CF patients chronically infected with P. aeruginosa were compared to isolates from CF patients colonized with this organism, both groups were found to contain comparable percentages of elastase-producing strains and mucoid strains. However, the group of isolates from colonized patients contained a higher percentage of strains producing alkaline protease and expressing general protease activity. In addition, the group of isolates from chronically infected patients contained more weakly proteolytic isolates than either the group from colonized CF patients or a group of isolates from pediatric patients without CF. These data suggest that protease production may be important in the initial colonization of the respiratory tract of CF patients by P. aeruginosa.
Cystic Fibrosis↗
Correlation of ultrastructure and function in calcium-tolerant myocytes isolated from the adult rat heart.
Explore the source record for details and available documents.
Animals↗
Use of the Luria-Nebraska Neuropsychological Battery in aphasia: a conceptual critique.
Explore the source record for details and available documents.
Aphasia↗
Detection by enzyme-linked immunosorbent assays of antibody specific for Pseudomonas proteases and exotoxin A in sera from cystic fibrosis patients.
Enzyme-linked immunosorbent assays were developed to measure serum antibody specific for Pseudomonas elastase, alkaline protease, and exotoxin A. Antibody responses to each Pseudomonas antigen were measured in cystic fibrosis (CF) patients who were not colonized with Pseudomonas aeruginosa, in those who were colonized, in those who were chronically infected with this organism, and in control subjects. Antibody levels for each antigen in the colonized and infected CF patients were higher than levels in uncolonized CF patients or non-CF control subjects. The antibody responses to elastase were similar in patients of the colonized and infected groups. However, infected CF patients had significantly elevated levels of antibody to exotoxin A (P less than 0.01) and alkaline protease (P less than 0.05) when compared with patients simply colonized with P. aeruginosa. These findings confirm that Pseudomonas alkaline protease, elastase, and exotoxin A are produced by Pseudomonas strains which colonize and infect CF patients. As an adjunct to established procedures (X-ray, microbiological culture, etc.), the antitoxin and anti-protease enzyme-linked immunosorbent assays may be clinically useful tests for differentiating colonized CF patients from those who have more severe Pseudomonas pulmonary infections.
ADP Ribose Transferases↗