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J L Erickson

Publications and source records attributed to J L Erickson.

9 recordsLinked to original sources
PubMed1987

Physiologic changes during high field strength MR imaging.

High field strength MR imaging systems may require several kilowatts of RF power to obtain images. A fraction of this power is absorbed by the patient, and changes in body temperature have been measured in experimental animals. The purpose of this study was to quantify changes in body surface temperature and other physiologic parameters in humans during MR scanning at 1.5 T. Blood pressure, heart rate, respiration, and axillary temperature measurements were obtained on 27 normal volunteers. Measurements were made at RF power levels of 0, 0.2, and 0.8 W/kg, with the power sequence randomized. In 14 volunteers receiving lumbar scans, statistically significant increases in temperature were observed at RF power levels of 0.2 (+0.2 +/- 0.1 degree C) and 0.8 (+0.5 +/- 0.1 degree C) W/kg. No significant changes related to RF power were observed in blood pressure or respiratory rate. At the 0.8 W/kg level there was a slight increase in heart rate (3 +/- 1.3 beats per minute). In the 13 patients receiving head scans, physiologic changes were substantially smaller. The temperature increases and other physiologic changes observed during MR scanning with the 1.5 T imager at RF powers of 0.2 and 0.8 W/kg were small and of no clinical concern. Additional studies should be performed in patients with cardiac failure, vascular occulusion, and metallic implants or prostheses.

Adult↗
PubMed1986

Factors affecting the loss of mitochondrial function in autolyzing cardiac muscle.

Rates of loss of mitochondrial respiratory function were monitored during autolyses of canine myocardial samples pretreated so as to affect tissue pH and/or tissue ATP content prevailing during tissue autolysis. When autolyses occurred under conditions of differing tissue pH, but at nearly identical tissue ATP levels, the rate of loss of mitochondrial function was virtually unchanged suggesting that tissue acidosis in the absence of a concomitant tissue ATP differential had little or no effect upon the rate of progression of mitochondrial damage. In a second comparison, autolyses were carried out at constant tissue pH, but where tissue ATP content differed dramatically. Here, the rate of loss of mitochondrial function was increased markedly suggesting that tissue ATP depletion in the absence of a concomitant tissue pH differential had a major effect upon the rate of loss of mitochondrial function. Thus, of the two parameters studied, tissue ATP content alone was far more important than tissue pH alone in determining the rate of cell membrane damage during ischemia. Finally, autolyses were carried out where both tissue pH and ATP content differed. Here, an even more dramatic increase in the rate of progression of mitochondrial damage occurred suggesting the operation of synergism between tissue ATP depletion and acidosis in promoting cell injury in ischemic cardiac muscle.

Acidosis↗
PubMed1986

Effects of oligomycin and acidosis on rates of ATP depletion in ischemic heart muscle.

The perfusion of canine cardiac muscle with 10 microM oligomycin produced a nearly 90% slowing of the net rate of tissue ATP depletion from 0.200 to 0.025 mumol X min-1 X g wet wt-1 of tissue during a subsequent myocardial autolytic interval during which tissue pH was held constant. Moreover, lowering the tissue pH during the autolytic process by 0.6 unit from approximately 6.8 to approximately 6.2 produced a nearly 60% slowing of the net rate of tissue ATP depletion from 0.200 to 0.087 mumol X min-1 X g wet wt-1. The pH dependence of the net rate of tissue ATP depletion (by an oligomycin-sensitive process) was that predicted from the mitochondrial ATPase pH-inhibition profiles reported earlier (J. Biol. Chem. 258: 9657-9661, 1983). When taken together with our observation that the mitochondrial ATPase comprises approximately 90% of the total of all of the ATP hydrolyzing activities present in cardiac muscle cells, data reported here suggest that the protonic inhibition of the mitochondrial ATPase plays a major role in regulating the rate of tissue ATP depletion during myocardial ischemia.

Acidosis↗
PubMed1985

Occupational risks for pleural mesothelioma in Sweden, 1961-79.

From national population-based registries linking cancer incidence from 1961 to 1979 with 1960 census data on industry and occupation for all employed individuals in Sweden, a systematic assessment was made of pleural mesothelioma occurrence according to occupational and industrial classifications. There were 318 cases of pleural mesothelioma recorded during the 19-year follow-up period among males employed in 1960, with significant variation by industrial and occupational categorizations. The observed number of pleural mesotheliomas for men employed in the sugar refining, cellulose, wood and pulp, shipbuilding, and railroad equipment manufacturing industries was more than three times the number expected. Occupations with at least twofold excess of mesotheliomas included the craftsman categories of plumbers, mechanics and repairmen, electricians, painters, tire makers, and stationary equipment operators. Our findings are consistent with available data relating mesothelioma to occupational asbestos exposure in other countries, although unexpected associations were found that deserve further epidemiologic study.

Female↗
PubMed1979

Effects of hypothermia on propranolol kinetics.

Propranolol may be uniquely useful in cardiac surgical procedures, since beta adrenergic blockade can prevent the hypokalemia and associated arrhythmias which result from systemic hypothermia. To determine the effects of hypothermic cardiopulmonary bypass (HCPB) on the in vivo handling of propranolol, serial drug plasma concentrations (Cp) were measured during HCPB in 12 patients who had been treated chronically with propranolol prior to surgery. Although no further propranolol was given during the procedure, Cp values (corrected for plasma volume dilution) were higher during hypothermia than in the preoperative period, falling to or below control levels after rewarming. Due to the variables inherent in patient surgery, meaningful kinetic analysis could not be carried out. Therefore, intravenous propranolol (1 mg/kg) was given twice to each of 5 dogs, first after anesthesia only, then after anesthesia and systemic cooling to 26 degrees in a water bath Cp values measured serially over 2 hr after drug administration were consistently higher during hypothermia. Compared with the paired normothermic control studies, hypothermia markedly reduced the apparent volume of distribution (6.78 +/- 1.65 vs 2.08 +/- 0.58 L/kg; p less than 0.001) and the total body clearance of propranolol (64.4 +/- 11.0 vs 32.3 +/- 7.2 ml/kg/min; p less than 0.005). These data show that hypothermia substantially alters the pharmacokinetics of propranolol, resulting in plasma drug levels higher than those predicted from kinetic patterns derived under normothermic conditions.

Adult↗
PubMed1977

Evaluation of applanation tonometers for the dog eye.

The Mackay-Marg, pneumatonograph, TonAir, and EMT-20 tonometers were evaluated in the normal dog eye. Tonometric scale readings were compared to the manometric recordings from the anterior chamber. The Mackay-Marg tonometer evaluated in open and closed systems was the most reliable (goodness of fit [r2] = 0.96) with intraocular pressure up to 100 mm. Hg. The pneumatonograph also exhibited high reliability (r2 = 0.92) but tended to underestimate intraocular pressures above 40 to 50 mm. Hg. The TonAir and EMT-20 tonometers were the least satisfactory for the dog, with r2 of 0.77 and 0.66 to 0.81, respectively. The Mackay-Marg is the most satisfactory tonometer for the dog.

Animals↗
PubMed1975

Evaluation of tear formation in the dog, using a modification of the Schirmer tear test.

The Schirmer tear test for the measurement of tear formation in the dog was done according to 2 procedures: Schirmer I (the conventional procedure) and SCHIRMER II (with topical anesthesia and drying of the ventral conjunctival fornix. Results from 97 normal dogs averaged 21.0 mm wetting/minute (standard deviation (sd) plus or minus 4.2 mm) for the Schirmer I test and 11.6 mm wetting/minute (sd plus or minus 6.1 mm) for the Schirmer II test. When atropine was injected subcutaneously in 50 dogs (0.02 mg/kg, wetting/minute averaged 9.36 mm (Schirmer I) AND 4.32 MM (Schirmer II). Two dogs in each of 3 groups had either the lacrimal gland, gland of the membrane nictitans, or both excised. Changes in tear formation were evaluated by Schirmer I and II tear tests, as well as after parenteral administration of atropine. The lacrimal gland, the gland of the membrama mocotams. amd tje accessory lacrimal glands and mucous cells were found to contribute 6.17, 35.2, and 3.1%, respectively, to tear formation.

Animals↗