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Biomedical subjects

K R Olson

Publications and source records attributed to K R Olson.

At least 109 records · Page 6Linked to original sources
PubMed1986

Plasma clearance, metabolism, and tissue accumulation of 3H-labeled catecholamines in trout.

Plasma clearance, metabolism, and tissue accumulation of [3H]norepinephrine (NE) and [3H]epinephrine (E) were measured after injection into the dorsal aorta of chronically catheterized trout, Salmo gairdneri. Sucrose, an inert volume marker, was injected with the catecholamines (CAs). Ion-exchange chromatography was used to separate unmetabolized CAs from deaminated and O-methylated metabolites in plasma. Both CAs are cleared from plasma at an exponential two-component rate. By 10 min postinjection, CA-specific extraction lowered plasma [3H]NE by 65% and [3H]E by 50%. Over 80% of the 3H remaining in plasma 10 min after injection was metabolized to O-methylated and deaminated products. Thus trout are able to quickly and efficiently lower circulating CA levels through tissue accumulation and metabolism. Kidney, liver, spleen, and atrium accumulate more CA than other tissues, although most tissues bind CA to some extent. Gills preferentially accumulate CAs over sucrose. Skeletal muscle has a low affinity for CAs but by virtue of its large mass may be an important organ in CA metabolism. NE is removed from the circulation faster, and more NE is bound to tissues than E. A blood-brain barrier for E but not NE was observed.

Animals↗
PubMed1986

Extraction and metabolism of circulating catecholamines by the trout gill.

Extraction and metabolism of [3H]-norepinephrine (NE) and [3H]epinephrine (E) by the respiratory (efferent branchial) and filamental (venous) vasculature of the trout gill were examined using an isolated perfused arch technique in which outflow from the two circulations was separated. Deaminated and O-methylated metabolites in the effluent were identified by ion-exchange chromatography. Metabolism by tissue homogenates was also measured. Gill homogenates deaminate catecholamines (CAs) faster than homogenates of liver, kidney, and skeletal muscle; branchial O-methylation was comparable to that of liver and kidney. The perfused gill extracted 60% of a NE pulse and 47% of an E pulse. During continuous CA perfusion the gill removed greater than 30% of the NE from the circulation through extraction and metabolism; only 7% of the E was removed. The gill venous system extracts and metabolizes more CAs than the efferent. NE is the preferred substrate for extraction and metabolism. A mechanism is proposed whereby high circulating CA levels, common during stress, are maintained through CA-induced reduction in venous blood flow. After the stress is alleviated, CA levels begin to fall, flow to the venous pathway increases, and the rate of inactivation of circulating CAs increases.

Animals↗
PubMed1986

Angiotensin extraction by trout tissues in vivo and metabolism by the perfused gill.

Plasma clearance and tissue accumulation of 125I-angiotensin I, [Asp1, Ile5]ANG I, and [14C]sucrose, an inert volume reference, were measured after a bolus injection into the dorsal aorta of rainbow trout, Salmo gairdneri. Retention and metabolism of ANG I to angiotensin II (ANG II) and their constituent 1-4 peptide by the gill were examined using an isolated perfused arch preparation in which outflow from the respiratory and central filamental (venous) pathways was separated. Clearance of ANG I from plasma is multiexponential, reflecting dilution and tissue extraction. Liver, bile, gonads, corpuscles of Stannius, and white skeletal muscle accumulate more 125I than 14C; gill tissue accumulates less 125I than 14C. ANG I and II are retained by the perfused gill longer than the inert vascular marker sucrose, even though the distribution volumes of the former are less. The gill respiratory pathway converts ANG I to ANG II whereas the venous pathway metabolizes either ANG I or II to the 1-4 peptide and other metabolites. The gill respiratory pathway is in series with the systemic vasculature, has a large blood-cell contact area, and, like the mammalian lung, is ideally suited to activate ANG I. The gill venous pathway is in parallel with the systemic vasculature and removes ANG II from the circulation. During stress, elevated plasma catecholamines may reduce venous perfusion and thereby help maintain elevated circulating ANG II levels through reduced venous metabolism.

Angiotensin I↗
PubMed1986

Trout vascular and renal responses to atrial natriuretic factor and heart extracts.

Dorsal aortic pressure (DAP), urine flow rate, and urinary K+, Na+, and Cl- were monitored in chronically catheterized unanesthetized rainbow trout before and after injection of saline, tissue extracts, or synthetic (rat, Ile-26) atrial natriuretic factor (ANF). Synthetic ANF (1.0 and 10.0 micrograms/kg body wt) and extracts from trout atria and ventricles increased DAP, urine flow rate, and electrolyte excretion. Saline, skeletal muscle extracts, and 0.1 microgram/kg body wt synthetic ANF had no effect on DAP and only minor effects on renal water and ion excretion. The slow-onset long-duration pressor response to ANF and heart extracts contrasted with a rapid short-acting pressor effect of epinephrine. Synthetic ANF (10 micrograms/kg body wt) and ventricular extracts produced marked increases in Na+ and Cl- excretion but only a mild diuresis. Much of the increase in urine flow rate appears to be due to solvent injection. These results show that trout hearts contain an ANF-like material and that mammalian and piscine ANF produce hemodynamic and renal effects upon intra-arterial injection.

Animals↗
PubMed1986

Occupationally related illness reported to a regional poison control center.

The San Francisco Bay Area Regional Poison Control Center studied 189 cases of toxic workplace exposure occurring over a six-month period in the belief that Regional Poison Control Center reporting could be a useful surveillance measure for occupational disease. Dermatitis was a relatively uncommon occurrence, but systemic complaints were frequent, a pattern differing from that seen in standard occupational surveillance programs. As compared to chemically caused illness detected through a statewide physician reporting program in California, increases in proportional frequencies of certain industrial chemical causes were observed. A matching strategy utilizing the physician reporting system identified only 15.9 per cent of poison control center cases that appear to have been otherwise detected through established surveillance. A nationwide system of Regional Poison Control Centers already exists with a computerized data base in place. This study indicates that these centers could be utilized as a supplementary system for acute occupational illness related to chemical exposures.

Adolescent↗
PubMed1986

Amatoxin poisoning in northern California, 1982-1983.

Twenty-two patients who ate mushrooms containing hepatotoxic amatoxins were treated during the fall and winter seasons of 1982 and 1983. All patients were treated with intensive supportive care and repeated oral doses of activated charcoal. In two patients fulminant hepatic failure developed and they died. One patient in whom encephalopathy developed had an orthotopic liver transplant and survived. Liver biopsy specimens obtained from five patients during the acute illness showed centrilobular hemorrhagic necrosis. The hepatic histopathology in a biopsy specimen from a 5-year-old boy eight weeks after mushrooms were eaten showed bands of fibrosis and islands of hepatocytes suggestive of early cirrhosis. Radioimmunoassay for amanitins, done on the serum from all patients, detected the toxins in only three, probably because most of the specimens were obtained 24 hours or more after the ingestion. This series, with a mortality rate of 9%, illustrates the outcome in patients who receive intensive supportive care and provides a background on which success of specific treatments should be judged.

Adolescent↗
PubMed1985

Theophylline overdose: acute single ingestion versus chronic repeated overmedication.

Currently available guidelines for managing theophylline intoxication do not distinguish between acute single ingestion and chronic repeated overmedication and do not reliably predict which patients should undergo hemoperfusion. Although hemoperfusion is widely recommended when serum concentrations exceed 40-60 mg/l, many patients with acute overdose tolerate much higher levels without serious toxicity. Because manifestations of toxicity might be dependent on the chronicity of the overdose, the authors retrospectively compared the clinical features of 15 patients with chronic repeated overmedication with those of 27 patients suffering acute single overdose. Patients suffering chronic repeated overmedication developed seizures (7/15) and serious arrhythmias (4/15) with serum levels of 28-70 mg/l. By contrast, only one of 19 patients suffering acute single overdose with peak levels less than 100 mg/l had seizures, and only two of 19 with levels less than 100 mg/l had serious arrhythmias. However, of the eight single-overdose patients with levels over 100 mg/l, seven had seizures and three had serious arrhythmias. Single-overdose patients were easily recognized by the presence of hypotension, hypokalemia, and low serum bicarbonate, features not present in chronic-type patients. Thus, while patients with theophylline overdose caused by chronic repeated overmedication frequently develop seizures and arrhythmias with serum levels of 40-70 mg/l, those with acute single ingestion are highly unlikely to suffer serious complications unless serum levels exceed 100 mg/l. Management of the intoxication, especially selection of patients for hemoperfusion, should be based on whether the overdose is caused by an acute single ingestion or chronic repeated overmedication.

Acute Disease↗
PubMed1984

Randomized study of the treatment of phenobarbital overdose with repeated doses of activated charcoal.

We performed a prospective randomized study of the effectiveness of repeated oral doses of activated charcoal in the treatment of phenobarbital overdose. Ten comatose patients who required intubation and mechanical ventilation completed the protocol. Five patients received repeated doses of activated charcoal and sorbitol. Five other patients who received a single dose of charcoal and cathartic served as control subjects. The serum half-life of phenobarbital (mean +/- SD, 36 +/- 13 hours) during repeated administration of charcoal and sorbitol was significantly shorter than that after charcoal administration was discontinued (93 +/- 7 hours) and shorter than the half-life in the single-dose group (93 +/- 52 hours). The length of time that patients in each group required mechanical ventilation, 39 +/- 24 hours (single-dose group) and 48 +/- 8 hours (repeated-dose group), did not differ significantly, nor did the time spent in the hospital. Although administration of repeated doses of activated charcoal to patients with phenobarbital overdose significantly increased the elimination of phenobarbital, it had no clear effects on the patients' clinical course.

Administration, Oral↗
PubMed1984

Microvasculature of the avian eye: studies on the eye of the duckling with microcorrosion casting, scanning electron microscopy, and stereology.

The microvasculature of the eye of the duckling was studied with microcorrosion casting, scanning electron microscopy, and stereology. Most blood to the eyeball first passes through the arterial ophthalmic rete mirabile, a complex of small arteries which intermixes with a similar complex of veins (venous ophthalmic rete mirabile) at the ventrotemporal angle of the eye. The present study reveals the ultrastructural anatomy and the compact, three-dimensional arrangement of vessels in this rete, which had been shown by previous investigators to function as a countercurrent heat exchanger. Vessels from this rete include the supraorbital and infraorbital arteries, which supply the eyeball anteriorly, and the ophthalmotemporal artery, which supplies the eyeball posteriorly. The internal ophthalmic and ethmoidal arteries, branches of the cerebral carotid artery, anastomose with the ophthalmotemporal artery posteriorly. Blood is distributed to the eyeball anteriorly by two ring arteries: the iridial ring artery, which circumscribes the iris and which receives blood from the long ciliary and infraorbital arteries; and the more peripheral, ciliary ring artery, which receives blood mostly from the infraorbital and ethmoidal arteries. Within the iris is a dense, freely anastomosing bed of capillaries which extends to the edge of the pupil and then loops back beneath the ciliary body. The vasculature of the ciliary body consists of radially arranged plates of anastomosing capillaries of irregular bore which mimic the contours of that organ, but permit changes in pupil diameter. The present study demonstrates the three-dimensional anatomy of the very dense capillary net of the choriocapillaris deep to the retina and the capillary mass of the pecten, and thus supports the finding of earlier investigators that nutrients diffusing from these structures nourish the avascular retina. The pecten consists of a pleated sheet of freely anastomosing capillaries which protrudes into the vitreous body from near the optic nerve. The choriocapillaris and the pecten are supplied by branches of the ophthalmotemporal artery: the former by numerous short posterior ciliary arteries, the latter by two or three arteries which further divide into one or two smaller vessels for each of its folds. Veins of the choroid layer at the periphery of the anterior surface of the eyeball, and to some extent on its lateral walls, are revealed by the corrosion-casting technique as unusual, flattened vessels of large caliber which lie in closely spaced parallel arrays. The large surface area thus created may function in heat dissipation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Angiotensin-converting enzyme activity in tissues of the rainbow trout.

Angiotensin-converting enzyme activity (ACE) was assayed in homogenized rainbow trout tissues and plasma. The physiological role of ACE was examined by injection of the ACE inhibitor captopril (SQ 14,225) into the dorsal aorta of chronically cannulated trout. Gills and corpuscles of Stannius exhibited greatest ACE activity and contained over 30 times more enzyme than plasma on a per-wet-weight basis. ACE was barely detectable in skeletal muscle, liver, and kidney tissues. Captopril lowered dorsal aortic pressure (DAP) within 1 min after injection. Pressure fell 5-7 mm Hg below control over the next 30 min and remained at this level for an additional hour. Because the gills receive the entire cardiac output they are, like the mammalian lungs, ideally situated to regulate plasma hormone levels. Activation of angiotensin II (AII) appears to be only one example of branchial metabolic capability.

Animals↗
PubMed1984

Carbon monoxide poisoning: mechanisms, presentation, and controversies in management.

Carbon monoxide (CO) remains the leading cause of death due to poisoning in the United States. CO produces toxicity by binding to hemoglobin, thereby reducing oxygen-carrying capacity, and by binding to myoglobin, which may impair cardiac output and result in cerebral ischemia. Severe CO poisoning results in coma or encephalopathy, but milder intoxication may occur with nonspecific symptoms suggestive of hysteria, hyperventilation, psychosis, or viral syndrome. Survivors of severe CO poisoning may have permanent neurologic or neuropsychiatric sequelae. Subtle memory deficits or personality changes may not be readily apparent to the examining physician. Administration of 100% oxygen at ambient pressure remains convenient, safe, and inexpensive. Hyperbaric oxygen can shorten the half-life of carboxyhemoglobin and can carry oxygen independent of hemoglobin. However, it is not known if either 100% oxygen or hyperbaric oxygen can actually alter mortality or improve neurologic outcome in survivors. Carefully controlled prospective studies should be carried out to assess the potential value of hyperbaric oxygen in CO poisoning.

Brain Edema↗
PubMed1984

Benefit of hemoperfusion in acute theophylline intoxication.

Charcoal and resin hemoperfusion or hemodialysis can accelerate theophylline elimination. Their benefit in the treatment of poisoned patients has been accepted on the basis of case reports. We reviewed the treatment of 26 patients with acute theophylline intoxication to determine how much of an effect hemoperfusion or hemodialysis had on the hospital course and outcome of the overdose. Eighteen patients received supportive care and eight patients hemoperfusion (HP) or hemodialysis (HD). The HP/HD patients had more severe theophylline intoxication on the basis of admission and peak theophylline levels, degree of hypotension and occurrence of arrhythmias. During HP/HD, theophylline concentrations decreased, heart rate slowed, blood pressure increased and evidence of central nervous system effects diminished. Despite the severe intoxication in the HP/HD groups, duration of clinical toxicity was shorter (13.5 +/- 7.1 vs. 21.6 +/- 14.1 hr) than in the control group. Seizures occurred in patients in both groups, but there was higher mortality or neurological morbidity in the supportive care (3/4) than in the HP/HD (1/5) group. Our study provides evidence that HP/HD can reduce the duration of clinical intoxication and probably reduces mortality and morbidity in patients with severe theophylline intoxication.

Adolescent↗
PubMed1984

Environmental and drug-induced hyperthermia. Pathophysiology, recognition, and management.

Environmental heat illness may affect the aged and infirm as well as the athletic. In addition, intoxication with a variety of drugs and toxins can produce hyperthermia, which may be indistinguishable from environmental heat illness. This article reviews current concepts of the pathophysiology, recognition, and management of environmental and drug-induced hyperthermia.

Adaptation, Physiological↗
PubMed1984

Intestinal infarction complicating phenobarbital overdose.

Nonocclusive intestinal infarction developed in a 29-year-old man after phenobarbital overdose. He was found 72 hours after the overdose, at which time examination of the abdomen disclosed no abnormalities and he was not hypotensive. During the next ten hours, abdominal distention, ileus, and gas within the intestinal wall and portal venous system developed. Laparotomy disclosed ischemic intestinal infarction of the right colon and distal ileum with no evidence of thrombosis of the mesenteric vessels. The patient recovered fully after ileostomy with subsequent reanastomosis. To our knowledge, ischemic intestinal infarction after drug overdose has not been reported previously.

Adult↗
PubMed1983

Effects of perfusion pressure on the morphology of the central sinus in the trout gill filament.

The central sinus, a prominent component of the nonrespiratory, ionoregulatory vasculature of the fish gill has been variously described as a simple sack-like structure in the eel A. anguilla and as an intricate series of parallel vessels in the catfish I. punctatus. To resolve whether these differences are interspecific or methodological, corrosion replicas of the central sinus in the rainbow trout (Salmo gairdneri) were prepared at physiological and superphysiological perfusion pressures with a low-viscosity methyl methacrylate resin. At physiological perfusion pressure (30 mmHg, 4.0 kPa), the central sinus vasculature appears as a series of parallel vessels traversing the filament beneath, and in register with, the interlamellar filamental epithelium. At elevated perfusion pressure (55-65 mmHg, 7.3-8.7 kPa) the sinus becomes greatly distended and sack-like and the vessels appear to coalesce. These changes are most pronounced in the basal area of the filament and along the efferent filamental artery. The results show that the interpretation of the vascular organization of the central sinus is highly dependent on methodology. In addition, the sensitivity of the central sinus to changes in perfusion pressure suggests that the sinus plays a dynamic role in intrabranchial hemodynamics.

Animals↗