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Biomedical subjects

K Frank

Publications and source records attributed to K Frank.

149 records · Page 9Linked to original sources
PubMedDate not supplied

Multiparametric evaluation of brain functions in the Mongolian gerbil in vivo.

We have developed the multiprobe assembly (MPA) by which metabolic, ionic and electrical activities can be monitored from the surface of the brain. In the present study we included optical fibers for the monitoring of intracapillary hemoglobin oxygenation by use of the Erlangen Microlight Guide Spectrophotometer (EMPHO-I) from the surface of the gerbil brain. The newly developed MPA provides simultaneous information about oxygen delivery (oxydeoxy Hb), tissue pO2 level, as well as the intracellular oxygen balance (intramitochondrial redox state). The ionic homeostasis was evaluated by monitoring extracellular K+ and Ca2+ activities reflecting the permeability changes of cation channels as well as the activities of Na+,K(+)-ATPase and other ion linked transport processes. The electrical activities were monitored by a bipolar electrocortical surface probe and DC steady potential. The subjects of the present study were Mongolian gerbils (Meriones unguiculatus) anesthetized and operated according to our routine techniques. After 30 min of recovery from the operation each gerbil was exposed to a short anoxia, graded hypoxia, ischemia as well as spreading depression. The results can be summarized as follows: 1. A clear correlation was recorded between the changes in oxydeoxy Hb spectra, tissue pO2 level and oxidation-reduction state of intramitochondrial NADH under oxygen deficiency situations (hypoxia, ischemia). 2. Blood volume changes under various perturbations monitored by various probes (366 reflectance and EMPHO-I) correlated very well with each other. 3. The degree of inhibition of Na+,K(+)-ATPase induced by oxygen deficiency could be interpreted by changes in extracellular levels of K+ measured by the surface mini-electrode. 4. Brain stimulation induced by spreading depression mechanism led to transient changes in ionic homeostasis and increase in energy requirements. The major HbO2 response was an increase in oxygenation due to the large CBF increase as monitored by the laser Doppler flowmeter. 5. Changes in oxy-deoxy Hb under fast scanning of 500-600 nm during 2-3 seconds of bilateral carotid arterial occlusion provided an indirect index for tissue O2 consumption.

Animals↗
PubMedDate not supplied

Membrane association of the Rieske iron-sulfur protein.

The mode of membrane attachment of the Rieske iron-sulfur proteins from cytochrome b6f complex of pea thylakoids and from cytochrome bc1 complex of yeast mitochondria has been studied using biochemical approaches. The relative sensitivity of the Rieske protein to trypsin in the thylakoid membrane shows that all trypsin sites of the Rieske protein are on the lumen side of the thylakoid membrane. In contrast to cytochrome f the chloroplast Rieske protein was extracted from thylakoids using chaotropic agents (NaSCN, urea), an alkaline pH and relatively low concentrations of Trinon X-100. The cytochrome bc1 complex Rieske protein from mitochondrial membranes of yeast was also released by NaSCN and alkaline treatment. The results presented here led us to the conclusion that the mitochondrial and chloroplast Rieske proteins are extrinsic and that their association with the rest of the complex involves hydrophobic interactions.

Antibodies↗
PubMedDate not supplied

A brief educational intervention for patients with rheumatic disease chosen to be presented in a clinic conference.

Being presented in a case conference can be anxiety-provoking and intimidating for the patient. We observed that patients, at times, would show signs of apparent discomfort. A structured interview of the patient was designed to assess, address, and clarify concerns the patient might have beforehand. The patients' concerns were communicated to the staff. The structured interview was given to 31 patients before they were presented. An additional 14 patients were interviewed after the conference about their experience without the prior interview. One year later, we followed up by interviewing another 15 patients who had been selected for clinic conference cases. The structured interview revealed confusion on the patient's part about the purpose of the conference, and a desire for information about the physical setting and who would be there. Patients wanted to be introduced formally when entering the room and to be thanked when leaving, and preferred to be questioned directly about their symptoms. Of the 31 patients interviewed before the conference, 23 (74%) reported that the conference was a positive experience when questioned afterward, compared with only 9 of 14 (64%) of those who were not interviewed before the conference. The results of this study were presented to the clinic staff, and education of the patients was stressed as a primary responsibility. At the follow up, 12 of the 15 patients reported real understanding of the clinic conference purpose. The only patient who reported being uncomfortable with the clinic conference and unwilling to attend another was the only patient who reported not being informed about what the conference entailed. It can be too easy for medical staff to forget that what is routine to them is very unusual and can be very stressful to the patient.

Adult↗