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J Olson

Publications and source records attributed to J Olson.

At least 145 records · Page 8Linked to original sources
PubMed1982

Rat cerebral cortical slice respiration in media of various osmolarities.

Freshly separated immature (5-day-old) and mature (60-day-old) rat cerebral cortical tissue demonstrates a Na+-dependent respiratory component similar to that recently described in primary cultured astrocytes. This respiratory component, which is not coupled to oxidative phosphorylation, increases as the osmolarity is increased above 354 mOsm in media with NaCl as the osmotic agent. With decreasing osmolarity from 354 to 80 mOsm, this respiratory component decreases more in cortical tissue than in cultured astrocytes. We propose that the respiratory response of neurons to decreasing extracellular osmolarity may differ from that of astrocytes in situ.

Animals↗
PubMed1982

Respiration and cell volume of primary cultured cerebral astrocytes in media of various osmolarities.

Respiration and cell volume of cerebral astrocytes from primary culture were measured in media of various osmolarities. Respiration was measured in 3T3 fibroblasts under similar conditions. Uncoupled respiration and respiration independent of oxidative phosphorylation were obtained by adding dinitrophenol and oligomycin, respectively. In NaCl media, dinitrophenol-stimulated respiration was inhibited at low and high osmolarities. With increasing osmolarity from 363 to 1185 mOsm, oligomycin-insensitive respiration increased and became the predominant respiratory component. The same respiratory changes in response to altered osmolarity were observed in 3T3 fibroblasts. In astrocytes, the oligomycin-insensitive respiration also increased in hyperosmolar sodium acetate media but was unchanged with increasing osmolarity in choline chloride or sucrose media. The increase in oligomycin-insensitive respiration in hyperosmolar NaCl media was blocked by amiloride, an inhibitor of passive Na+ movement. In contrast to amiloride, ouabain, an inhibitor of Na+, K+-ATPase, inhibited a constant amount of respiration with increasing NaCl concentration. The relationship of astrocyte volume to osmolarity was the same in hyper-osmolar media containing NaCl or sucrose. Cell volumes were greater in hypo-osmolar NaCl than in sucrose media. Our results suggest the presence of a Na+-dependent respiratory component in primary cultured cerebral astrocytes in media of increased osmolarity. This respiratory component is not coupled to oxidative phosphorylation or a Na+-K+-ATPase. It may be important in the proposed physiologic role of the astrocyte in maintaining brain extracellular water content and electrolyte concentrations.

Animals↗
PubMed1982

In vitro cellular respiration at elevated temperatures in developing rat cerebral cortex.

Cellular respiration in vitro was studied in cerebral cortical tissue from rats 2-60 days of age. Respiration was measured polarographically over the temperature range 34-44 degrees C in tissue slices in a basal condition; maximally stimulated by an uncoupler of oxidative phosphorylation, dinitrophenol; and inhibited by a blocker of mitochondrial oxidative phosphorylation, oligomycin. Basal respiration at 34 degrees C increased about 80% between 7 and 30 days of age. Oligomycin-insensitive respiration did not change with age. Dinitrophenol-stimulated respiration was unchanged from 2 to 10 days and then increased over 100% between 10 and 15 days of age. The Q10 for dinitrophenol-stimulated respiration increased from a value of 1 in tissue from rats 2-10 days of age to about 2 in tissue from rats 15 days and older. Our results confirm the previously reported maturational increases in basal respiration and in respiratory capacity in rat cerebral cortical tissue. The maturational increase in maximal respiratory capacity occurs in a short age interval coincident with a marked increase in the Q10 for the hyperthermic temperature range. Both these properties may be important in the increasing resistance to hyperthermia-induced seizures and their functional sequelae in the rat pup.

Animals↗
PubMed1982

Development of resistance to lead encephalopathy during maturation in the rat pup.

The purpose of this study was to determine the maturational period during which the rat pup becomes resistant to the toxic effects of lead on the brain. Pups were fed lead, as lead acetate, by esophageal catheter for 14 days beginning at various ages between 14-24 days. The daily lead doses, which produced a hemorrhagic cerebellar encephalopathy in at least 50% of pups, were 400 micrograms Pb/g body weight for animals fed from 14 days of age, 800 micrograms/g for animals fed from 16 days, and 1600 micrograms/g for animals fed from 18 days. In contrast, pups fed even higher lead doses beginning at 20 days showed only a patchy cerebellar edema by light microscopy while pups fed from 24 days had normal cerebellums by light microscopy. The encephalopathic lead doses in the younger pups resulted in the same cerebellar lead concentrations (about 30 micrograms/g protein) as the higher lead doses fed pups beginning at 20 ot 24 days. When corrected for blood lead concentrations, the cerebellar lead concentrations were 20-25% higher in the encephalopathic compared to the older encephalopathy-resistant animals. This difference may be accounted for by cerebellar hemorrhages in the younger animals. Polarographic studies showed inhibition of respiration in cerebellar slices from animals fed lead from 14 days of age but not in animals fed from 20 or 24 days of age. Our results that, during the encephalopathy-sensitive age period, a critical cerebellar concentration of lead is associated with the encephalopathy. Resistance to lead encephalopathy in older animals, with similar cerebellar lead concentrations, may be related to a capacity to sequester lead in new cellular locations away from its site of action on aerobic energy metabolism.

Age Factors↗
PubMed1982

Maturation of potassium-stimulated respiration in rat cerebral cortical slices.

Maximal dinitrophenol-stimulated respiration and K+-stimulated respiration were measured polarographically in cerebral cortical slices taken from rats aged 2-60 days. Increasing K+ concentrations produced an increase in respiration in slices from animals aged 15 days and older, but not in slices from animals aged 10 days and younger. Dinitrophenol-stimulated respiration, or the maximal respiratory capacity of the tissue, showed a similar increase between 10 and 15 days of age. At each age the maximal respiratory capacity was 6-8 ng at 0/mg protein min greater than the maximal K+-stimulated respiration.

2,4-Dinitrophenol↗
PubMed1982

Scanning electron microscopic study of lead effects on cerebral astrocytes in primary culture.

The effects of lead acetate on the cell surface of primary cultured astrocytes from dissociated neonatal rat cerebrums were studied using scanning electron microscopy. Astrocytes, grown for two weeks in a modified Eagle's minimal essential medium containing 20% calf serum, were exposed to lead (1, 10, 30, 50, or 100 micrograms Pb/ml) for four days. Astrocytes grown in lead-free medium showed membrane folds (ruffles) and microvilli on the surfaces of perikarya. Vesicular structures or blebs (gliosomes) were scattered on the surfaces of perikarya and branched cell processes. Cultures exposed to 1 microgram Pb/ml were indistinguishable from controls. After exposure to 10 and 30 micrograms Pb/ml, microvilli disappeared, membrane folds were less extensive, and the number of surface blebs increased. Astrocytes exposed to 50 micrograms Pb/ml showed no surface membrane folds or microvilli while the blebs increased sufficiently to cover the surface of the perikarya. Cells treated with the highest lead concentration (100 micrograms/ml) were shrunken and perikarya again were covered with blebs. Transmission electron microscopy of the cells exposed to 10-100 micrograms Pb/ml showed membrane bound vacuoles and areas of cytoplasmic clearing, some of which may correspond to the surface blebs seen by SEM. These studies suggest that the changes in the cell surface resulting from lead exposure represent a toxic effect of lead on primary cultured astrocytes.

Animals↗
PubMed1982

Solitary osteochondroma masquerading as a possible malignant lesion.

The object of this presentation is to discuss the characteristics of a few primary bone tumors (osteochondroma versus chondrosarcoma), as presented in the literature, in relation to a specific lesion that the authors encountered. The specific lesion, an unusual osteochondroma arising from the plantar aspect of the first metatarsal, had a few characteristics of its own that are presented. This case report includes the pertinent history and clinical findings of the lesion with associated radiographic laboratory and pathology results that are very essential in determining an accurate differential diagnosis. The surgical discussion and postoperative care is important in discussing the particular characteristics of this tumor and the pattern of its regrowth. Recurrence of a lesion of this type is very rare and, when it does occur, must undergo much scrutiny. This regrowth is the most perplexing characteristic of this tumor and the reason for the lengthy presentation. The final diagnosis remained osteochondroma with benign postoperative ectopic bone formation. It is the authors' opinion that this is a very atypical lesion in the study of bone tumors and is a worthwhile presentation to the literature as such.

Adolescent↗
PubMed1981

Hyperthermia-induced seizures in the rat pup: a model for febrile convulsions in children.

Seizures were produced in rat pups by ambient hyperthermia. Seizure threshold temperatures, measured rectally and intracerebrally, increased between 2 and 10 days of age. Electrocortical paroxysmal discharges were confirmed in hyperthermic 6- and 10-day-old pups. The increasing resistance to hyperthermic seizures with maturation and the electroencephalographic changes induced by hyperthermia are similar to those in young children.

Age Factors↗
PubMed1981

Effect of bovine viral diarrhea virus on conception in cattle.

Sixty adult dairy cows were used to study the effect of bovine viral diarrhea (BVD) virus on conception when inoculated with the virus within 2 hours after breeding. Fifteen cows were assigned at random to each of 4 groups. Group I (control) cows were given 3 ml of diluent in the uterus; group II (seropositive) cows were given 3 ml of BVD virus in the uterus; group III (seronegative) cows were given 3 ml of BVD virus in the uterus; and group IV (seronegative) cows were given 3 ml of BVD virus orally and 3 ml intranasally. At 35 days after breeding, the cows were slaughtered, their reproductive tracts were recovered, and pregnancy rates were recorded. The pregnancy rates for groups I, II, III, and IV were 67%, 60%, 27%, and 67%, respectively. The group III pregnancy rate was significantly lower (P less than 0.05) than that for the control group. However, the similarity of rates for groups I, II, and IV indicates that BVD virus does not inhibit conception when cattle are infected by natural routes or when virus is infused into the uterus of seropositive cows at the time of breeding. These results indicate that BVD virus is not a major cause of repeat breedings in cattle.

Animals↗
PubMed1980

Intrathoracic extramedullary hematopoiesis: report of a case in a patient with sickle-cell disease-beta-thalassemia.

A case of paravertebral extramedullary hematopoiesis in a patient with sickle-cell anemia-beta-thalassemia is reported. Interesting aspects in this case, including the high level of Hb F and large number of nucleated erythrocytes in the peripheral blood, are discussed. Fifty-five cases of intrathoracic extramedullary hematopoiesis have been reported. Most of these cases occurred in patients with thalassemia or hereditary spherocytosis. Extramedullary hematopoiesis should be considered in the differential diagnosis of a posterior mediastinal mass in a patient who has chronic anemia or other syndromes associated with extramedullary hematopoiesis.

Aged↗