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Biomedical subjects

C M Collins

Publications and source records attributed to C M Collins.

At least 19 recordsLinked to original sources
PubMed1992

Group G streptococcal M protein exhibits structural features analogous to those of class I M protein of group A streptococci.

We have previously studied a collection of group G streptococcal strains isolated from bacteremic human infections and demonstrated that such strains resist phagocytosis by human polymorphonuclear leukocytes but are type specifically opsonized by homologous antiserum. We have now performed Southern hybridization analysis on genomic DNA from eight blood isolates. All eight isolates showed DNA homology to a group A emm24 gene probe. The M-protein gene of one of the isolates, strain 1750, has now been isolated. This gene (emmG1) encodes a polypeptide of 67 kDa (MG1) which is reactive with antibodies to the partially purified M protein of the parent strain. The predicted amino acid structure of MG1 demonstrates significant identity with the carboxy terminus (C, D, and anchor domains) of M6 and M24 but only limited identity with the amino terminus (variable portion) of these group A M proteins. Southern hybridization of genomic DNA of the eight group G blood isolates with an emmG1 gene probe indicated there were at least four emm alleles associated with these strains. These studies indicate that M proteins of group G streptococci, like those of group A, are genetically heterogeneous. Moreover, MG1 appears to conform to the recently proposed class I structure of M-protein molecules and thus shares certain distinct structural features with the M proteins of well-established rheumatogenic group A streptococcal serotypes. Further comparison of the structures of group G and group A M proteins of throat and skin isolates may cast light on those configurations of the M protein molecules which are and are not critical for the expression of rheumatogenicity.

Amino Acid Sequence↗
PubMed1992

Insertional inactivation of an Escherichia coli urease gene by IS3411.

Ureolytic Escherichia coli are unusual clinical isolates that are found at various extraintestinal sites of infection, predominantly the urinary tract. The urease-positive phenotype is unstable in approximately 25% of these isolates, and urease-negative segregants are produced at a high frequency. We have studied the nature of the urease-positive-to-negative transition in one of these isolates, designated E. coli 1021. Southern hybridization experiments with genomic DNA extracted from seven independent E. coli 1021 urease-negative segregants revealed the presence of a 1.3-kb DNA insertion in the urease gene cluster. A DNA fragment containing the DNA insertion was cloned from one of the urease-negative segregants. This cloned DNA fragment was capable of mediating cointegrate formation with the conjugative plasmid pOX38, suggesting that the DNA insertion was a transposable element. The insert was identified as an IS3411 element in ureG by DNA sequence analysis. A 3-bp target duplication (CTG) flanking the insertion element was found. DNA spanning the insertion site was amplified from the other six urease-negative segregants by using the polymerase chain reaction. The DNA sequence of the amplified fragments indicated that an IS3411 element was found in an identical site in all urease-negative segregants examined. These data suggest that in E. coli 1021, IS3411 transposes at a high frequency into ureG at a CTG site, disrupting this gene and eliminating urease activity.

Base Sequence↗
PubMed1992

White phosphorus poisoning of waterfowl in an Alaskan salt marsh.

The cause of the yearly death of an estimated 1,000 to 2,000 migrating dabbling ducks (Anas spp.) and 10 to 50 swans (Cygnus buccinator and C. columbianus) has remained a mystery for the last ten years in Eagle River Flats (ERF), a 1,000 ha estuarine salt marsh near Anchorage, Alaska, used for artillery training by the U.S. Army. We have gathered evidence that the cause of this mortality is the highly toxic, incendiary munition white phosphorus (P4). The symptoms of poisoning we observed in wild ducks included lethargy, repeated drinking, and head shaking and rolling. Death was preceded by convulsions. Farm-reared mallards dosed with white phosphorus showed nearly identical behavioral symptoms to those of wild ducks that became sick in ERF. White phosphorus does not occur in nature but was found in both the sediments where dabbling ducks and swans feed and in the gizzards of all carcasses collected in ERF. We hypothesize that feeding waterfowl are ingesting small particles of the highly toxic, incendiary munition P4 stored in the bottom anoxic sediments of shallow salt marsh ponds.

Adipose Tissue↗
PubMed1991

Efficacy of a Proteus mirabilis outer membrane protein vaccine in preventing experimental Proteus pyelonephritis in a BALB/c mouse model.

A BALB/c mouse model of nonobstructive, ascending Proteus mirabilis pyelonephritis was characterized bacteriologically, histologically, and serologically from 3 to 28 days. Intravesicular administration of 2 X 10(8) P. mirabilis K7 resulted in the septic death of 9 (16%) of 57 mice by day 15. Among the survivors, K7 colonized the kidneys in great numbers until day 21. Histological examination of the kidneys revealed acute inflammation which was characterized by neutrophil infiltration by day 3, renal necrosis by day 7, and fibroblastic infiltration by day 14 which persisted at least until day 28. The immunoglobulin G response to the outer membrane proteins (OMP) was assessed by enzyme-linked immunosorbent assay and Western blotting (immunoblotting). Anti-OMP immunoglobulin G antibodies were detected as early as day 7, and the reciprocals of their titers rose progressively up to day 28 (i.e., greater than or equal to 500). This model was also used to assess the efficacy of OMP and lipopolysaccharide (LPS) immunization in preventing renal infection. K7 OMP or LPS (100 micrograms) preparations were administered intramuscularly in Freund's complete adjuvant. After 2 weeks, mice were intravesicularly challenged with 2 X 10(8) bacteria of the homologous K7 strain or one of four heterologous strains. Compared with the saline-immunized control group and K7 LPS-immunized mice, K7 OMP recipients were protected from death when challenged by homologous or heterologous strains. In addition, K7 OMP recipients were protected (P less than 0.003) from subsequent renal infection when challenged by the K7 strain and had more rapid bacterial renal clearance when challenged by three of four heterologous strains. OMP recipients produced antibodies which bound major OMP moieties (viz., 36- to 39-kDa cell wall constituents) as assessed by Western blotting. These results support the concept that immunization with selected bacterial protein surface coat constituents can prevent uromucosal infection by interfering with colonization or renal injury.

Animals↗
PubMed1990

Genetic analysis of Escherichia coli urease genes: evidence for two distinct loci.

Studies with two uropathogenic urease-producing Escherichia coli strains, 1021 and 1440, indicated that the urease genes of each are distinct. Recombinant plasmids encoding urease activity from E. coli 1021 and 1440 differed in their restriction endonuclease cleavage sites and showed minimal DNA hybridization under stringent conditions. The polypeptides encoded by the DNA fragments containing the 1021 and 1440 urease loci differed in electrophoretic mobility under reducing conditions. Regulation of urease gene expression differed in the two ureolytic E. coli. The E. coli 1021 locus is probably chromosomally encoded and has DNA homology to Klebsiella, Citrobacter, Enterobacter, and Serratia species and to about one-half of the urease-producing E. coli tested. The E. coli 1440 locus is plasmid encoded; plasmids with DNA homology to the 1440 locus probe were found in urease-producing Salmonella spp., Providencia stuartii, and two E. coli isolates. In addition, the 1440 urease probe was homologous to Proteus mirabilis DNA.

Blotting, Southern↗
PubMed1988

Genetic analysis of an Escherichia coli urease locus: evidence of DNA rearrangement.

Ureolytic Escherichia coli strains are uncommon clinical isolates. The urease phenotype in a large percentage of these isolates is unstable and lost upon storage. We examined two urease-positive uropathogenic E. coli isolates that give off urease-negative segregants and determined that the urease phenotype was chromosomally encoded. The urease phenotype was cloned from E. coli 1021 and found to be encoded on a 9.4-kilobase HindIII restriction fragment. Transposon mutagenesis indicated that at least 3.2 kilobases of this fragment were necessary for production of urease. The urease recombinant plasmid pURE coded for at least four insert-specific polypeptides as determined by maxicell analysis. Disruption of the region encoding two of these polypeptides (67 and 27 kilodaltons) abolished urease activity. Analysis by Southern hybridization of urease-positive E. coli 1021 and seven independently isolated urease-negative segregants showed that a DNA rearrangement was associated with the urease-negative phenotype.

Chromosomes, Bacterial↗
PubMed1987

Right ventricular dysfunction and the exercise limitation of chronic obstructive pulmonary disease.

This study examined right ventricular function during exercise in patients with chronic obstructive pulmonary disease to answer the following questions: Is there a significant correlation between oxygen consumption at maximal exercise and exercise right ventricular ejection fraction? Does the right ventricular ejection fraction response to exercise correlate with exercise changes in pulmonary artery pressure, total pulmonary resistance or pulmonary vascular resistance? Which combinations of cardiac, ventilatory and blood gas variables are the best predictors of oxygen consumption at maximal exercise? Twenty-six patients with stable chronic obstructive pulmonary disease performed symptom-limited supine bicycle exercise with simultaneous hemodynamic and radionuclide ventriculographic measurements. The oxygen consumption at maximal exercise correlated with the exercise right ventricular ejection fraction (n = 21, r = 0.66; p less than 0.005), exercise stroke volume (r = 0.68; p less than 0.001), exercise cardiac output (r = 0.77; p less than 0.00005) and exercise ventilation (r = 0.85; p less than 0.00001). The change in right ventricular ejection fraction from rest to exercise correlated inversely with the change from rest to exercise in total pulmonary resistance (r = -0.51; p less than 0.05) but not with the change in mean pulmonary pressure (r = -0.37) or in pulmonary vascular resistance (r = 0.09). Multivariate analysis showed that the variables giving the highest combined correlation with oxygen consumption were ventilation and right ventricular ejection fraction (r = 0.95, adjusted r2 = 0.88). These results suggest that exercise oxygen consumption of patients with chronic obstructive pulmonary disease is related to right ventricular systolic function, exercise right ventricular dysfunction is related, in part, to abnormal exercise total pulmonary resistance, and exercise limitation in chronic obstructive pulmonary disease occurs as a result of the dynamic interaction between disordered right heart function and ventilation.

Adult↗
PubMed1986

Diphtheria toxin can simultaneously bind to its receptor and adenylyl-(3',5')-uridine 3'-monophosphate.

Diphtheria toxin that was bound to receptors on BS-C-1 cells was able to bind approximately 1 molar equiv of adenylyl-(3',5')-uridine 3'-monophosphate (ApUp). In contrast, receptor-bound CRM197, a mutant form of toxin with greatly diminished affinity for dinucleotides, did not bind ApUp. Affinity of the dinucleotide for receptor-bound toxin differed from that for free toxin by less than an order of magnitude. These results indicate that the receptor site and the ApUp site on the toxin do not significantly overlap.

Animals↗
PubMed1985

Circular dichroism of diphtheria toxin, Pseudomonas aeruginosa exotoxin A, and various derivatives.

We have recorded the near- and far-ultraviolet circular dichroism spectra of diphtheria toxin, Pseudomonas aeruginosa exotoxin A, and derivatives of these toxins. The far-ultraviolet spectra of various forms of diphtheria toxin were virtually identical, implying that no major changes in secondary structure accompany proteolytic nicking or dimerization of toxin, or binding of the endogenous dinucleotide, adenylyl-(3'-5')-uridine 3'-monophosphate (AdoPUrdP). Alpha-helix content was estimated to be 29%, as compared with 8% for fragment A. Near-ultraviolet spectra were identical between nicked and intact diphtheria toxin. A broad negative transition with a minimum at 304 nm was assigned to the intrachain disulfide bridge within the B moiety. Dimeric diphtheria toxin showed perturbations of aromatic residues. Binding of AdoPUrdP to monomeric diphtheria toxin or of adenylyl-(3',5')-uridine (AdoPUrd) to fragment A perturbed one or more tryptophans. The latter results correlate with evidence for involvement of a tryptophan in NAD binding. Native exotoxin A was estimated to have 16% alpha-helix, and the activated form of exotoxin A, 11%. An enzymically active, 31 kDa proteolytic fragment of exotoxin A showed similar alpha-helix content (7%) to that of diphtheria toxin fragment A.

ADP Ribose Transferases↗
PubMed1985

A monoclonal antibody that detects HLA-D region antigen in routinely fixed, wax embedded sections of normal and neoplastic lymphoid tissues.

We describe the use of a monoclonal antibody (TAL-IB5) to HLA-D region alpha-chains that reacts well with HLA-D positive cells in normal and neoplastic lymphoid tissues fixed in routine fixatives and embedded in paraffin wax in the conventional fashion. This antibody should prove to be useful in routine histological investigations of lymphoid and possibly other neoplasms as well as other non-neoplastic conditions where the immune system plays an important part.

Antibodies, Monoclonal↗