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Biomedical subjects

R E Carlson

Publications and source records attributed to R E Carlson.

At least 19 recordsLinked to original sources
PubMed1992

Effect of reduction in myocardial edema on myocardial blood flow and ventricular function after coronary reperfusion.

The contribution of myocardial edema to the no-reflow phenomenon, left ventricular functional recovery, and infarct size after coronary occlusion and reperfusion is uncertain. To examine this, we studied 26 open-chest dogs after coronary occlusion and reperfusion. Twelve dogs received hypertonic mannitol 30 min before reperfusion, which increased serum osmolality (P less than 0.01 vs. control). Fourteen control dogs received a similar volume of saline that had no effect on serum osmolality. Tissue biopsies of central ischemic and normal myocardial areas were analyzed by proton nuclear magnetic resonance relaxation spectroscopy to assess edema content. Hypertonic mannitol resulted in a significant decrease in ischemic tissue T1 (767.0 +/- 16.3 vs. 818.6 +/- 19.0 ms, P less than 0.05) compared with the control group. Despite this, no significant differences were found between the mannitol and control groups in 4-h reperfusion subendocardial blood flow or left ventricular wall thickening. In addition, mannitol administered before reperfusion did not modify infarct size compared with the control group (infarct/risk area, 41.0 +/- 1.4 vs. 37.9 +/- 1.9%, P not significant). In conclusion, no benefit is produced in reperfusion blood flow or functional recovery by reducing edema in postischemic myocardial tissue. This suggests that mechanisms other than myocardial edema are responsible for myocardial no reflow and contractile dysfunction after coronary reperfusion. Furthermore, hypertonic mannitol administered before reperfusion does not reduce infarct size.

Animals↗
PubMed1991

Transmural distribution of myocardial edema by NMR relaxometry following myocardial ischemia and reperfusion.

To determine the distribution and extent of myocardial edema resulting from ischemia and reperfusion, seven open-chest dogs underwent occlusion of the left circumflex coronary artery for 2 hours (group I), and 10 underwent occlusion for 2 hours and reperfusion for 2 hours (group II). Proton nuclear magnetic resonance spectroscopy (T1 and T2 relaxation times) and percent water content were determined to quantitate the amount of edema. There was a transmural increase of the T1 relaxation time of the central ischemic zone in groups I and II, although this increase was significantly greater in group II in both the subendocardium (group I = 707.8 +/- 12.5 msec, group II = 813.2 +/- 36.2 msec; p less than 0.01) and subepicardium (group I = 641.7 +/- 20.5 msec, group II = 760.5 +/- 34.7 msec; p less than 0.01). These increases were also observed in the T2 weighted relaxation time in the subendocardium (group I = 54.7 +/- 0.8 msec, group II = 78.7 +/- 6.3 msec; p less than 0.005) and subepicardium (group I = 54.0 +/- 1.4 msec, group II = 73.1 +/- 4.0 msec; p less than 0.001). Transmural differences were evident between the myocardial layers with increased T1 relaxation times (p less than 0.01) in the subendocardium in both groups. Similar increases were noted in the percent water content of the myocardium. Thus T1 and T2 relaxation times lengthened with an increase in myocardial water content following occlusion, and these relaxation times were augmented by reperfusion. We conclude that ischemia-induced edema occurs in a transmural distribution from subendocardium to subepicardium following occlusion, and this edema is further enhanced by reperfusion.

Animals↗
PubMed1991

Breaking the incest cycle: the group as a surrogate family.

1. Adult women who are survivors of incest can work on healing issues during long-term group therapy sessions. 2. Group therapy sessions can assist survivors to deal with unresolved family issues. 3. Group therapy sessions can be facilitated by psychiatric nurses who are college faculty when a nursing center is affiliated with a college of nursing.

Adult↗
PubMed1989

Neutrophil depletion fails to modify myocardial no reflow and functional recovery after coronary reperfusion.

Recent studies suggest that neutrophil accumulation and activation in postischemic myocardium may be responsible for myocardial no reflow, which is characterized by an incomplete restoration of blood flow after reperfusion. To examine this further, 11 open chest, anesthetized dogs received bolus injections of a bovine neutrophil antiserum that produced an average 81 +/- 5% depletion of circulating neutrophils, and 10 control dogs received nonimmune serum. Each animal underwent 2 h of left circumflex artery occlusion followed by 4 h of reperfusion. Simultaneous two-dimensional echocardiography and radioactive microsphere blood flow studies were performed at baseline, 2 h of occlusion and early (approximately 5 min) and 4 h of reperfusion. During occlusion, both groups developed similar reductions in myocardial blood flow and levels of ischemic zone myocardial wall thinning. At early reperfusion, similar levels of hyperemia and regional hypokinesia were observed for both groups. By late reperfusion, both groups experienced significant no reflow in the subendocardium (p less than 0.05) and reduced reflow in the mid-myocardium. Regional depression in ischemic zone function persisted throughout the reperfusion period in both groups. However, infarct size expressed as a percent of left ventricular weight, assessed by triphenyltetrazolium chloride staining, was smaller for the neutrophil depletion group compared with the control group (8.7 +/- 1.3% versus 13.1 +/- 1.8%, p less than 0.05). It is concluded that an 81% neutrophil depletion fails to modify the no reflow phenomenon or improve functional recovery after 2 h of coronary artery occlusion and 4 h of coronary reperfusion despite modification of the ultimate size of necrosis.

Animals↗
PubMed1988

The effect of different mechanisms of myocardial ischemia on left ventricular function.

Myocardial ischemia may be produced by limitation of blood flow as in abrupt coronary occlusion, termed supply-type ischemia, or by increasing myocardial oxygen demand in the setting of restricted flow, termed demand-type ischemia. To examine the comparative extent and severity of the dysfunction related to both forms of ischemia, we studied anesthetized, open-chest dogs by means of two-dimensional echocardiography and tracer microspheres. Supply-type ischemia was produced by total occlusion of the LCx (n = 7); demand-type ischemia was induced by infusion of dobutamine after creation of a critical LCx stenosis (n = 6). At the time of the production of ischemia, the group with demand-type ischemia had significant increases in both heart rate (p less than 0.05) and mean arterial pressure (p less than 0.05), whereas the group with supply-type ischemia had a decrease in mean arterial pressure (p less than 0.05). Subendocardial blood flow in the LCx region was severely depressed in supply-type ischemia (0.09 +/- 0.04 ml/min/gm) compared to demand-type ischemia (1.04 +/- 0.07 ml/min/gm; p less than 0.01). Although both groups of animals had an abnormality of left ventricular function during ischemia, as determined by two-dimensional echocardiography, the extent of the dysfunction in the group with supply-type ischemia was greater (146 +/- 12 degrees) compared to the group with demand-type ischemia (99 +/- 9 degrees; p less than 0.01). Similarly, the degree of left ventricular dysfunction in the group with supply-type ischemia was greater than that for the group with demand-type ischemia (p less than 0.05). Thus these data suggest that supply-type ischemia produced by coronary occlusion results in a greater extent and degree of left ventricular functional abnormality than pharmacologically induced demand-type ischemia.

Animals↗
PubMed1986

Response of the microflora in outdoor experimental streams to pentachlorophenol: environmental factors.

The 2nd year of a 2-year study of the fate of pentachlorophenol in outdoor artificial streams focused on details of microbial degradation by a combination of in situ and laboratory measurements. Replicate streams were dosed continuously at pentachlorophenol concentrations of 0, 48, and 144 micrograms/L, respectively, for an 88-d period during the summer of 1983. Pentachlorophenol was degraded both aerobically and anaerobically. Aerobic degradation was more rapid than anaerobic degradation. Mineralization of pentachlorophenol was concommitant with pentachlorophenol disappearance under aerobic conditions, but lagged behind loss of the parent molecule under anaerobic conditions. Biodegradation in the streams, or in specific stream compartments such as the sediment or water column, was characterized by an adaptation period (3-5 weeks for the stream as a whole, and reproducible from the previous year), which was inversely dependent on the concentration of pentachlorophenol and microbial biomass. The adaptation in the streams could be attributed to the time necessary for selective enrichment of an initially low population of pentachlorophenol degraders on surface compartments. The extent of biodegradation in the streams (percent loss of initial concentration of pentachlorophenol) increased with increasing pentachlorophenol input, which was explicable by an increase in the pentachlorophenol degrader population with increasing pentachlorophenol concentration. The sediment zone most significant to overall pentachlorophenol biodegradation was the top 0.5- to 1-cm layer as shown by pentachlorophenol migration rates and depth profiles of degrader density within the sediment. Pentachlorophenol profiles in sediment cores taken during and after the adaptation period for degradation showed that diffusion of pentachlorophenol into the sediment was rate limiting to degradation in this compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerobiosis↗
PubMed1985

Response of the microflora in outdoor experimental streams to pentachlorophenol: compartmental contributions.

Outdoor artificial streams were treated continuously with pentachlorophenol (PCP) for 88 days during the summer of 1983. The contributions of different stream compartments (microbial habitats) to microbial degradation of PCP were determined in a stream treated with 144 micrograms of PCP per liter. The 488-m long stream was composed of mud-bottomed pools alternating with gravel riffles. PCP loss in the stream attributable to microbial degradation after an adaptation period was in the range of 55 to 74%. Contributions to PCP loss were determined for rock surface (epilithic), macrophyte surface (epiphytic), sedimentary, and water column communities by measuring rates of PCP disappearance in stream water, containing ambient concentrations of PCP, in contact with representative compartmental samples. The specific capability, in units of micrograms of PCP per hour per square meter of stream cross-sectional area (macrophytes at maximum plant density, water column at mean depth, upper 10-cm layer of gravel), followed the order rock surface much greater than macrophytes greater than sediment approximately equal to water column. The compartmental contribution to total stream losses in units of grams per hour followed the same order, although the differences were smaller. The rate of PCP disappearance in the water column above sediment cores followed the order oxygen-rich greater than oxygen-poor approximately equal to anaerobic greater than sorption-only conditions. The large difference in specific capability between the rock surface and sediment compartments could be attributed to oxygen deficiency (because of chemical and biological oxygen demand) in the sediments. Free-floating and particle-attached organisms in the water column were important to PCP biodegradation.

Aerobiosis↗
PubMed1984

Senile reticular pigmentary degeneration.

Of 104 consecutive patients with senile reticular pigmentary degeneration (207 eyes), 85 patients (82%) were more than 60 years old (mean age, 69.2 +/- 8.54 years). Forty-nine (47%) were men and 55 (53%) were women. Peripheral visual fields were not characteristically constricted. Although most eyes tested had visual acuities of 20/50 or better, 69 eyes (33%) had visual acuities of 20/100 or worse. A total of 136 eyes (66%) had senile macular degeneration at the time senile reticular pigmentary degeneration was first diagnosed, whereas only 43 control eyes (21%) from the same referral population also had senile macular degeneration (P less than .001). Macular degeneration was the primary cause for reduced vision when it was noted. In no instance could reduced visual acuity or constricted visual fields be attributed to the senile reticular pigmentary degeneration alone. Senile reticular pigmentary degeneration on routine ophthalmoscopy should alert the clinician to the possibility of co-existing macular degenerative disease.

Aged↗
PubMed1984

An internal standard for porphyrin analysis.

The routine clinical analysis of the porphyrin precursors of heme requires an internal standard to determine the efficiency of the analytical procedure used. 2-Vinyl-4-hydroxymethyldeuteroporphyrin IX has been prepared as an internal standard. Its application to porphyrin analysis has been demonstrated using high-performance liquid chromatographic resolution of the uro- to protoporphyrins in normal and porphyric urine.

Chromatography, High Pressure Liquid↗
PubMed1984

An exploratory study of life-change events, social support and pregnancy decisions in adolescents.

This exploratory, descriptive study investigated the relationship of life-change events and family and social support to decision making in pregnant adolescents. The convenience sample consisted of 43 subjects aged 14 to 18 years coming to two midwestern clinics for pregnancy testing. Instruments were the Adolescent Life Change Event Questionnaire and the Demographic and Social Support Questionnaire. Data analysis involved three groups: continue the pregnancy (N = 30); abort (N = 9); and undecided (N = 4). Kruskal-Wallis one-way analysis of variance by ranks was used to test for differences between groups on overall life-change unit (LCU) scores and social support scores. Chi square, Fisher Exact Tests and step method multiple discriminant analysis were used to determine if specific life changes were more associated with particular outcome decisions. While not statistically significant, the overall LCU scores were higher and the social support scores lower for the continue group than for the abortion group. Subjects in the abortion group were younger, more likely to have experienced "getting grounded," and more involved in school and social activities. More subjects in the continue group reported personal and family health problems.

Abortion Applicants↗
PubMed1983

Biodegradation and photolysis of pentachlorophenol in artificial freshwater streams.

The biodegradation, photolysis, and adsorption of pentachlorophenol (PCP) in outdoor, aquatic environments were examined with man-made channels built by the U.S. Environmental Protection Agency at a field station on the Mississippi River near Monticello, Minn. Four channels were used, each channel being approximately 520 m long and receiving river water that flowed through the channels for about 10 h before reentering the river. The channels were dosed continuously during the summer of 1982 with various concentrations of PCP (approximately 0, 48, 144, and 432 micrograms/liter). We monitored the biotic and abiotic degradation of PCP in these channels for approximately 16 weeks. Photolysis of PCP was rapid at the water surface, but greatly attenuated with depth. Depending on sunlight conditions, photolysis accounted for a 5 to 28% decline in initial PCP concentration. Adsorption of PCP by sediment and uptake by biota accounted for less than 15% and probably less than 5% in unacclimated water. Microbial degradation of PCP became significant about 3 weeks after the initiation of dosing and eventually became the primary mechanism of PCP removal, accounting for a 26 to 46% (dose-dependent) decline in initial PCP. Most of the PCP-mineralizing microorganisms that developed in the channels were either attached to surfaces (e.g., rocks and macrophytes) or associated with surface sediments. Total bacterial numbers (direct microscopic counts) in the various channels were not affected significantly by PCP concentrations of micrograms per liter. Numerous strains of bacteria able to grow at the expense of PCP were isolated from the adapted channels. The experiments reported here will help predict the responses of flowing aquatic ecosystems to contamination by biocides such as pentachlorophenol.

Adsorption↗
PubMed1982

Isolation of chlorine-containing antibiotic from the freshwater cyanobacterium Scytonema hofmanni.

Scytonema hofmanni, a filamentous freshwater cyanobacterium (blue-green alga), produces secondary metabolites which inhibit the growth of other cyanobacteria and green algae. A rapid, qualitative assay for this inhibition has been developed with Synechococcus as the test organism. This assay procedure has led to the isolation and characterization of an antibiotic (named cyanobacterin) from Scytonema. The antibiotic has a molecular weight of 430 and an empirical formula of C23H23O6Cl and contains a gamma-lactone and a chlorinated aromatic nucleus. It inhibits the growth of various algae but has limited effect on nonphotosynthetic bacteria or protozoans and thus may have potential use as a specific algicide.

4-Butyrolactone↗
PubMed1982

Exophthalmos, global luxation, rapid weight gain: differential diagnosis.

Exophthalmos is an uncommon finding in the clinical setting; exophthalmos with global luxation is distinctly rare. Although the differential diagnosis of exophthalmos can be extensive, the most common causes are thyroid dysfunction and orbital neoplasia. We recently encountered a patient with exophthalmos and global luxation, the onset of which coincided with a weight gain of 45.5 kg (100 lb). An extensive evaluation failed to show any of the common states associated with either exophthalmos or global luxation. The ocular problems resolved with weight reduction only; the cause of both problems seems to have been the deposition of fat in the orbital fat pads. We found two previous reports of this condition in the older medical literature, with minimal clinical evaluations. Our patient was thoroughly studied to clarify the pathophysiologic characteristics of this unusual clinical appearance, and we reviewed the causes of exophthalmos and global luxation.

Body Weight↗