PubMed Health⌕ Search

Biomedical subjects

K Light

Publications and source records attributed to K Light.

10 recordsLinked to original sources
PubMed1991

Coordinate regulation of beta-lactamase induction and peptidoglycan composition by the amp operon.

The amp operon, which is located on the Escherichia coli chromosome, modulates the induction of plasmid-borne beta-lactamase genes by extracellular beta-lactam antibiotics. This suggests that the gene products AmpD and AmpE may function in the transduction of external signals. beta-Lactam antibiotics are analogs of cell wall components that can be released during cell wall morphogenesis of enterobacteria. The amp operon was studied to determine its importance in signal transduction during cell wall morphogenesis. The peptidoglycan compositions of amp mutants were determined by high-performance liquid chromatography and fast atom bombardment mass spectrometry. When a chromosomal or plasmid-borne copy of ampD was present, the amount of pentapeptide-containing muropeptides in the cell wall increased upon addition of the cell wall constituent diaminopimelic acid to the growth medium. These results suggest that beta-lactamase induction and modulation of the composition of the cell wall share elements of a regulatory circuit that involves AmpD. Escherichia coli requires AmpD to respond to extracellular signaling amino acids, such as diaminopimelic acid, and this signal transduction system may regulate peptidoglycan composition in response to cell wall turnover products.

Amino Acid Sequence↗
PubMed1989

Unusual composition of peptidoglycan in Bordetella pertussis.

The composition of the peptidoglycan of Bordetella pertussis and the nature of its turnover products was determined by a new combination of analytical techniques: high performance liquid chromatography of an enzymatic peptidoglycan hydrolysate and fast atom bombardment mass spectrometry and fast atom bombardment collision-activated dissociation tandem mass spectrometry. Sixteen major components of the peptidoglycan were purified, and assignment of complete or partial chemical structures was achieved for nine and seven species, respectively. At this level of resolution, a previously unrecognized heterogeneity of monomeric (five new species; nine total) and dimeric species (five new species; five total) was detected. No species containing diaminopimelyl-diaminopimelic acid cross-links or lysyl-arginine substitutions were found. Previous estimates of total cross-linkage and average chain length were revised downward to 32% and 21 disaccharide residues, respectively. Detection of a chemically novel species, a disaccharide octapeptide monomer, in both the peptidoglycan hydrolysate and culture supernatant fluid, suggests that an N-acetyl-muramyl-L-alanine amidase acts on the intact peptidoglycan of Bordetella and participates in cell wall turnover. Five peptidoglycan turnover products were identified in the supernatant fluid of late logarithmic phase cultures, including the 1,6-anhydro monomeric species known as tracheal cytotoxin. Peptidoglycan turnover was detected at a low rate of approximately 10%/generation, a value sufficient to account for the generation of all tracheal cytotoxin found in culture supernatant fluids.

Bordetella pertussis↗
PubMed1989

Is the ANA guilty of paternalism in its guidelines on withdrawing or withholding food and fluid?

The ANA Committee on Ethics's Guidelines on Withdrawing or Withholding Food and Fluid (1988) delineates those circumstances under which withholding is normally permissible. The Guidelines direct nurses to respect the wishes of competent adults. What of adults who are considered incompetent? Can they make decisions to refuse food and fluids? The Guidelines ask nurses to judge patient competence and the merit of the reasons behind the decisions. This suggests paternalism. A more appropriate role of the nurse might be to focus on helping the patient to make a decision, rather than on the merit of the decision itself.

American Nurses' Association↗
PubMed1986

Vasoactive intestinal polypeptide-, somatostatin- and substance P-immunoreactive nerves in the smooth and striated muscle of the intrinsic external urethral sphincter of patients with spinal cord injury.

Specimens obtained by transurethral sphincterectomy from patients with spinal cord injury and carcinoma of the bladder were studied immunohistochemically. In the smooth muscle region of the sphincter, vasoactive intestinal polypeptide-, substance P- and somatostatin-immunoreactive fluorescent, varicose nerve fibers were seen. In the striated muscle region, VIP-immunoreactive nerves were found around striated muscle fibers and bundles, while somatostatin- and substance P-immunoreactive nerves were confined to nerve bundles. In both the smooth and striated muscle regions of the intrinsic external urethral sphincter, VIP-immunoreactive nerves were seen around blood vessels. No differences were observed in the immunohistochemical localization of these peptide-containing nerves in the two groups of patients. No immunofluorescence for [Met]enkephalin, bombesin, neurotensin or serotonin was found in any nerves in the urethra.

Adolescent↗
PubMed1978

Current concepts in congenital vesico-ureteral reflux.

Primary vesico-ureteric reflux must be graded according to severity. Significant reflux up a dilated ureter appears to be an important factor in causing renal damage. There is evidence in favour of the theory that the renal deterioration seen in some cases of reflux can be explained on a congenital basis of site or origin of the ureteral bud and resultant dysplasia of the developing kidney. Surgery should be reserved for selected patients with significant reflux.

Adult↗
PubMed1977

Causes of renal deterioration in patients with meningomyelocoeles.

The patient records of 122 children with meningomyelocoeles were analysed in an attempt to find a common factor causing upper tract deterioration. The results clearly show that grade III reflux followed by obstructive hydroureter are the commonest factors associated with significant renal deterioration.

Child, Preschool↗
PubMed1977

Intermittent catheterisation in congenital neurogenic bladder: a preliminary report.

53 children with congenital neurogenic bladders are currently managed on intermittent catheterisation. The problems of continence, urinary tract infection and upper tract deterioration have to date been controlled reasonably successfully and the need for urinary diversion appears to have been obviated. Complications have been negligible and parents and patients alike prefer this method to the Crédé manoeuvre.

Adolescent↗