Sacral insufficiency stress fracture as etiology of positional autonomic dysreflexia: case report.

The medical literature is replete with case reports of the syndrome known as autonomic dysreflexia. Although the majority of cases are known to be induced by either bladder or bowel distention. there does exist a small number of cases in which the inciting stimulus is more obscure. In such cases, a comprehensive medical evaluation is necessary to ensure proper identification of the source of irritation and the appropriate medical management of the patient. We present a patient with a heretofore unreported suspected etiology of autonomic dysreflexia, axial loading of a sacral stress fracture.

Altered phospholipid composition in mutants of Escherichia coli sensitive or resistant to organic solvents.

Mutants of Escherichia coli with altered resistance to low molecular weight organic solvents were isolated. Solvent-resistant mutants showed a decrease in the ratio of phosphatidylethanolamine to the anionic phospholipids (phosphatidylglycerol and cardiolipin) relative to the wild-type, whereas solvent-sensitive strains showed an increase. Reversion studies on representative mutants demonstrated that the phenotypic response to solvents and the changes in phospholipid composition were genetically associated. The fatty acid and lipopolysaccharide compositions of the various mutants showed no significant differences from the parental strain. The lesions in two of the solvent-sensitive mutants (DC7 and DC9) and one of the resistant mutants (DC11) were mapped by cotransduction with phage P1 and shown to lie very close to the pss locus at 56 min on the Escherichia coli map.

Role of the cell surface in bacterial mating: requirement for intact mucopeptide in donors for the expression of surface exclusion in R+ strains of Escherichia coli.

Two derivatives of the F-like R factor R1drd19 carrying mutually exclusive resistance determinants were used to study the role of the mucopeptide in the expression of conjugal functions. The use of metabolically active penicillin spheroplasts in R+ times R- matings had no effect on the ability of the cells to donate or accept a plasmid. However, in R+ times R+ matings it was found that surface exclusion was totally abolished if the donor, but not the recipient, was a spheroplast. This result implies that the traS gene, expressed by the excluding plasmid, is dependent for its action on an intact mucopeptide layer in the donor cell, and that this interaction is independent of the transfer ability of the excluding plasmid.

Detection of a protein, similar to the sex pilus subunit, in the outer membrane of Escherichia coli cells carrying a derepressed F-like R factor.

The outer membranes of Escherichia coli K-12 cells carrying a derepressed F-like R factor contain about 7 times 10-4 molecules per cell of a protein similar to the subunit of the sex pili specified by the R factor. This protein pool is absent in cells carrying the repressed variant of the R factor. The size of the pool is about one-half of the amount of protein incorporated into mature sex pili at the peak of production and is independent of the phase of growth of the culture. The molecular weight of the protein in the pool and of the subunit of the sex pili specified by the cells is 12,500 plus or minus 600.

Male-specific bacteriophage MS2 propagation in fluorophenylalanine-resistant Escherichia coli K12.

Mutation of Escherichia coli K12 HfrH to resistance to fluorophenylalanine resulted in changes in the plaque morphology of bacteriophage MS2 on this strain and led to an increased efficiency of propagation of the phage in liquid cultures. Evidence was obtained that the mutation resulted in inhibition of early lysis in infected cells and that lysis involved the production of a lysozyme. Genetic studies suggested that the observed pleiotropy of the resistance mutation was due to informational suppression.

Purification of sex pili from Escherichia coli carrying a derepressed F-like R factor.

A procedure for the purification of sex pili is described. Escherichia coli K-12 carrying Rldrd19 was grown in nutrient broth and blended at the time of peak sex pilus production. The cells were removed by centrifugation, and the supernatant fraction was concentrated, dialyzed, and clarified in an ultrafiltration system. After an additional blend and a clearing spin, the material was centrifuged in a CsCl gradient, and the fractions containing the sex pili were subjected to isoelectric focusing. About 5 mg of intact pili of approximately 98% purity were obtained by this method from about 100 g (wet weight) of cells.