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Biomedical subjects

N Keller

Publications and source records attributed to N Keller.

136 records · Page 8Linked to original sources
PubMed1975

Hemodynamic, metabolic, and ultrastructural consequences of hyperosmolal mannitol after myocardial anoxia.

Recovery from anoxia has been evaluated in the isovolumic nonrecirculating paced perfused rat heart. Seventy studies were performed consisting of 1) 15 min of aerobic perfusion (AP), 2) AP + 15 min of anoxic perfusion, 3) AP + 15 min of anoxic perfusion + 15 min of reoxygenation. Krebs-Ringer-bicarbonate + 5 mM glucose (KRB) was compared with KRB + mannitol (osmolality, +60 mOsm). Mannitol decreased myocardial water content. It improved recovery of hemodynamic function after reoxygenation. With KRB alone left ventricular systolic peak pressure (LVSp) decreased by 32 percent and maximum dP/dt by 50 percent. With mannitol added LVSp decreased 18 percent and dP/dt 21 percent (p less than 0.01). No effect on energy metabolism was demonstrated. KRB and mannitol did not differentially affect total coronary flow, lactate, and glucose extraction, tissue glycogen, creatine phosphate, or adenine nucleotide concentrations. No significant difference in capillary filling was demonstrated by microfil injection. Mannitol appears to improve LV function by direct myocardial osmotic action unrelated to enhanced energy production.

Adenosine Diphosphate↗
PubMedDate not supplied

Prevalence of internalisation-associated gene, prtF1, among persisting group-A streptococcus strains isolated from asymptomatic carriers.

BACKGROUND: The failure of antibiotic treatment to eradicate group-A streptococci in up to 30% of patients with pharyngotonsillitis is unexplained. Some strains of group-A streptococci can enter respiratory epithelial cells, where they would be inaccessible to antibiotics unable to penetrate the cell membrane, such as penicillins. The fibronectin-binding proteins, F1 and SfbI, are needed for this process. We hypothesised, therefore, that an intracellular reservoir of group-A streptococci could account, at least partly, for failure to eradicate throat carriage, and that the presence of the gene for fibronectin-binding protein (F1) might be linked to the ability of a strain to persist in the throat after therapy. METHODS: We investigated the frequency of prtF1-containing strains among 67 patients with pharyngotonsillitis. All patients were clinically cured, although 13 of them continued to carry group-A streptococci in the throat during or after therapy. To distinguish between persisting and recolonising strains, isolates from the 13 patients were serologically tested and compared by polymorphic DNA-amplification technique. FINDINGS: 12 (92%) of the 13 patients with symptomless carriage had prtF1-containing strains in the throat, compared with 16 (30%) of the 54 patients with successful eradication (p=0.0001). Three of the 13 eradication-failure patients were recolonised with strains that differed from the pretreatment strains. Nine of the ten (90%) persisting strains carried prtF1 (p=0.0009). INTERPRETATION: Our findings suggest that protein-F1-mediated entry to cells is involved in the causative process of the carriage state.

Adhesins, Bacterial↗
PubMedDate not supplied

Ultrastructural study of the posterior cornea of the dogfish "Scyliorhinus canicula L".

The cornea of Elasmobranchs remains transparent and exhibits a remarkable resistance against swelling when deprived of its endothelium. Sutural fibers, which traverse the corneal stroma anteroposteriorly, may be responsible for this property. We studied the structure of the cornea of Scyliorhinus canicula L., a galeiform Elasmobranch, with special emphasis on the presence of a corneal endothelium and on its appearance during development. Observations were made with the aid of several microscopic techniques: light and specular microscopy, transmission and scanning electron microscopy. We found that the posterior corneal surface was always covered by a fibrillar material. A structural counterpart of endothelial-like cells on the posterior cornea or in the anterior chamber was never observed in adult fishes and in embryos of different stages. In contrast, in Torpedo ocellata, a torpediniform Elasmobranch, endothelial cells were seen. The significance of these findings is discussed in context with the possibility of technical artefacts and compared with other studies.

Animals↗