Evidence against erythropoietin production by the carotid body.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
A J Hansen
Publications and source records attributed to A J Hansen.
The distribution of tobacco mosaic virus in plant callus cultures.
Explore the source record for details and available documents.
Culture Media↗
Brain ion homeostasis in cerebral ischemia.
Brain function is severely disturbed in ischemia. Within seconds, consciousness and spontaneous activity is lost, whereas interstitial concentrations of major ions are kept near normal levels. After a few minutes, there is a dramatic increase of potassium and a lowering of sodium, chloride, and calcium concentrations. Similar ionic changes are observed during spreading depression, however, that is spontaneously reversible and may be elicited in the otherwise normally perfused brain. In focal ischemia, the two events occur simultaneously. The central core of very low flow displays the ischemic increase of interstitial potassium concentration, whereas the surrounding tissue exhibits repeated episodes of spreading depression. This may induce energy failure by stimulating metabolism in areas with depressed flow thereby causing cell damage outside the ischemic core.
Animals↗
Scar skin and dapple apple viroids are seed-borne and persistent in infected apple trees.
The closely related apple scar skin viroid (ASSV) and dapple apple viroid (DAV) were identified in whole seeds from infected pome fruits by hybridization of extracted nucleic acids with a 32P-labelled ASSV cRNA probe. Viroid amounts were greater in seed coats and subcoats than in seed cotyledons and embryos. ASSV or DAV was also detected in nucleic acid extracts from infected seeds, cotyledons and embryos by reverse transcription/polymerase chain reaction with viroid-cDNA-specific primers followed by Southern blot hybridization analysis of the amplified products with an ASSV cRNA probe. These results indicate that ASSV and DAV are seed-borne. ASSV and DAV were also found in the anthers, petals, receptacles, leaves, bark and roots of infected trees. The results suggest that viroid-infected trees constitute potential sources of the viroid in field spread. ASSV and DAV infections have been observed sporadically in commercial orchards in the United States and Canada and the infected trees have been eliminated. The use of viroid-free sources of seeds, seedlings, rootstocks and budwood should greatly reduce the risk of the future spread of the viroid.
Animals↗
Brain extracellular ion composition and EEG activity following 10 minutes ischemia in normo- and hyperglycemic rats.
Hyperglycemia severely impairs the outcome from cerebral ischemia. In order to sort out whether impaired brain ion homeostasis contributes extracellular "K+], [Ca++], and [H+] concentrations, [K+]e, [Ca++]e and [H+]e, of the brain cortex, as well as the EEG, were monitored during and after 10 minutes of complete cerebral ischemia in normo- and hyperglycemic rats. In both groups, the EEG-activity disappeared in 10-20 seconds of ischemia, at a time when [K+]e, [Ca++]e and [H+]e started to increase. After about 1.5 min, [K+]e showed an abrupt increase and [Ca++]e a steep decrease in the normoglycemic group. In the hyperglycemic group the same event took place after about 3 min of ischemia. pHe decreased to 6.6 and 6.1 in the normoglycemic and hyperglycemic group, respectively. Following the ischemic episode [K+]e reached pre-ischemic level after 4 min, [Ca++]e after 13 min, and [H+]e after 30 min in both groups. Recovery of the EEG, however, was clearly different in the 2 groups. EEG-activity reappeared later in the hyperglycemic group and showed after one hour a pattern of burst-suppression activity while the normoglycemic group showed asynchronous activity resembling the control pattern. It is concluded that high glucose content in brain prior to ischemia - and hence lower brain pH during ischemia - does not interfere with the return of normal extracellular ion composition after cerebral ischemia, whereas the return and pattern of EEG activity is severely affected.
Animals↗
Effects of a task failure exercise on the peroneus longus and brevis during perturbed gait.
Ankle inversion injuries represent the most common trauma sustained by athletes. Muscle fatigue from activity may contribute to a delay in the response of the ankle proprioceptors and dynamic restraints during unexpected inversion. The purpose of this investigation was to determine changes in peroneal average EMG, peak EMG, and time to peak EMG following a task failure exercise. Thirty-two subjects (age 20+/-1.43 yrs; 21 male, 11 female) with no lower extremity injuries reported for data collection. Data were collected from each subject's dominant leg using surface electromyography (EMG). EMG electrodes were applied over the peroneus longus (PL) and brevis (PB) using a standard protocol Subjects walked at a fixed pace on a 6.1 m runway with one section that could be unexpectedly dropped into 30 degrees of inversion upon foot contact. Trials with perturbed and unperturbed gait were randomized to reduce prediction of the unexpected inversion. Once 3 trials of perturbed gait were recorded, subjects completed an isotonic activity that isolated the peroneals. The task was completed to failure. Immediately following the task failure exercise, subjects walked on the perturbation runway once again until 3 trials of perturbed gait were recorded. Analysis revealed no significant differences with regard to average muscle activity between pre- and post-task failure exercise for the PL (F1,31 = 0.133; p = 0.718) or for the PB (F1,31 = 0.795; p = 0.380). There was also no significant difference in peak muscle activity pre- to post-task failure for the PL (F1,31 = 0.032; p = 0.859) or the PB (F1,31 = 0.156; p = 0.695). Finally, there was no significant difference in time-to-peak muscle activity pre- to post-task failure for the PL (F1,31 = 0.830; p = 0.369) or the PB (F1,31 = 1.037; p = 0.316). We concluded that the task failure exercise did not contribute to changes in peroneal activity during perturbed gait. These results indicate that peroneal fatigue does not play a significant role in the incidence of inversion ankle sprains.
Adult↗
Thromboangiitis obliterans affecting the upper extremity in a woman. Case report.
A rare case of thromboangiitis obliterans is reported, with involvement of the left brachial and axillary artery and signs of median-nerve denervation in a 42-year-old woman following long affection of the right popliteal artery. Arterial reconstruction of the upper extremity was beneficial when the patient stopped smoking. The histologic changes distinguished the condition from atherosclerosis.
Adult↗