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Biomedical subjects

K R Olson

Publications and source records attributed to K R Olson.

At least 91 records · Page 5Linked to original sources
PubMed1990

Vascular effects of kinins in trout and bradykinin metabolism by perfused gill.

In the preceding studies we have shown that elements of a kallikrein-kinin system (KKS) are present in trout. The present study examines the cardiovascular effects of intra-arterial kinin injection and the ability of perfused gills or gill homogenates to metabolize bradykinin or the pressor substance generated in trout plasma by glandular kallikrein (T60K). Bradykinin (BK), t-kinin, kallidin, and Met-kallidin produced pressor responses in vivo. BK responses were unaffected by alpha-adrenergic blockade or cyclooxygenase inhibition. Perfused gills extracted approximately 40% of a [3H]BK bolus, however, metabolites were not recovered from the effluent perfusate. Gill homogenates completely metabolized [3H]BK and inactivated the pressor substance T60K. Captopril reduced BK and T60K metabolism by gill homogenates. The present study demonstrates that kinins have pressor effects in trout that are not mediated through adrenergic or prostanoid-derived mechanisms. The results also suggest that trout do not release endothelium-derived relaxing factors in response to kinin injection. The gill is able to metabolize BK and T60K, although, with respect to BK, this process appears to involve intracellular hydrolysis and may be only partially dependent on angiotensin-converting enzyme. Inactivation of BK by gill tissue may be fundamentally different from kinin metabolism by the mammalian lung.

Animals↗
PubMed1990

Quantitative assessment and reduction of long-term autoradiographic background.

Quantitative autoradiography can measure distribution patterns in an animal exposed to radiolabeled compounds. A comparison of autoradiographs of rat brain containing low levels of 14C showed that a highly variable background signal had been produced. This resulted in several overexposed autoradiographs which could not be quantitatively compared. The background, believed to be produced by light emanating from the phosphor coating in the X-ray cassette, was a major impediment because it hindered correct analysis of the specimen. This article details our experiments demonstrating the sources of variance contributing to background and offers methods for its reduction. We found that placement of black polyethylene plastic between the slides and phosphor in the X-ray film cassette minimized autoradiographic background and effectively eliminated the effects caused by inherently different levels of radioactivity in the glass slides.

Animals↗
PubMed1990

Cocaine.

There has been a dramatic rise in the number of adverse medical effects related to cocaine abuse since the widespread introduction of crystallized freebase cocaine or "crack" in the mid-1980s. In particular, cardiovascular and central nervous system toxicity is becoming more widely recognized and requires aggressive medical management to prevent potentially high morbidity and mortality.

Cocaine↗
PubMed1990

Occupational illness and poison control centers. Referral patterns and service needs.

In a study of occupational illness reported to a regional poison control center and to gauge the center's outreach and services, we did follow-up interviews of 301 case contacts over a 6-month period. We ascertained referral routes, reasons for contacting the poison control center, and awareness of the center's function. For 122 cases a nonphysician was the initial poison control center contact. Of the nonphysician contacts, 41 had already consulted a health care provider and been referred to the poison control center for assistance. Of the 70 persons with exposure, only 21 had been aware before their exposures that poison control center services might include occupational chemical illness consultation. Physicians and nonphysicians expressed similar reasons for contacting the poison control center, with 118 of 301 identifying the need for an exposure hazard risk assessment. These data suggest that although those contacting a poison control center because of occupational illness include a variety of cases, they have many similar service needs.

Humans↗
PubMed1989

Occupational illness: case detection by poison control surveillance.

STUDY OBJECTIVE: To evaluate the usefulness of poison control center detection in occupational illness surveillance. DESIGN: Case series of all occupationally related exposures referred for poison control center consultation over 6 months. Follow-up structured interviews were done of exposed persons and health care providers. Cases were traced under established occupational illness reporting programs. SETTING: A regional poison control center. PATIENTS: Consecutive sample of 461 symptomatic occupational exposure cases. After exclusions and losses to follow-up, interview of 301 patients and the treating physician, physician's assistant, or nurse practitioner for the 223 of the patients under direct medical care. MEASUREMENTS AND MAIN RESULTS: One hundred and fifty-five persons (61%; CI, 55% to 67%) had systemic or respiratory illness; 109 (36%; CI, 31% to 41%) had eye or skin conditions. Work practices were associated with exposures more often than technical failure; 118 persons (39%; CI, 33% to 45%) reported lack of respirators or other appropriate personal protective equipment. For 223 persons who received direct medical care, only five treating health care providers (2%; CI, 0.2% to 4%) reported occupational specialization, although occupational care was a regular practice activity for 128 of the health care providers (57%; CI, 51% to 63%). Sixty-seven cases (22%; CI, 17% to 27%) were detected by the Doctor's First Report surveillance program; 97 cases (32%; CI, 27% to 37%) comprised the maximal detection estimated for Occupational Safety and Health Administration surveillance. CONCLUSIONS: Poison control center detection provides a useful surveillance measure for occupational illness. The proportion of case detection failures by established surveillance programs suggests that the incidence of occupational illness in the United States, which is calculated from these incomplete programs, may be three to five times greater than previously estimated.

Adult↗
PubMed1989

Localization of angiotensin-converting enzyme in the trout gill.

Angiotensin-converting enzyme (ACE) was localized in perfused trout gills by measuring gill extraction of two radiolabeled ACE inhibitors, 125I-351A (an iodinated derivative of lisinopril) and 3H-RAC-X-65, and by autoradiography of gills perfused with 125I-351A. A 125I-351A pulse was preferentially extracted by the arterio-arterial (AA) pathway (61.7% +/- 1.8% extraction; mean +/- SE, N = 4); the arteriovenous (AV) pathway extracted an additional 10%. Extraction by either pathway was reduced by simultaneous perfusion with 10(-5) M unlabeled lisinopril. AA extraction of RAC-X-65 during continuous perfusion was maximal (75% +/- 5%, N = 6) during the first few minutes of perfusion and decreased steadily to 38% +/- 9% by 20 min and to less than 10% by 40 min. AV extraction of RAC-X-65 was negligible. Autoradiography of gills continuously perfused with 125I-351A showed that the radiolabel was concentrated in the respiratory lamellae. The highest grain density was associated with the pillar cells nearest the medial (inner) lamellar margin. Afferent filamental arteries and afferent lamellar arterioles were labeled to a lesser extent. Relatively little label was found on the efferent lamellar arterioles or efferent filamental arteries. 125I-351A binding was not evident in AV vessels. These findings support the hypothesis that the gill is an important site for formation of plasma angiotensin II and they suggest that enzymes associated with mammalian endothelial cells are also common to gill pillar cells.

Animals↗
PubMed1989

Value of rapid screening for acetaminophen in all patients with intentional drug overdose.

We performed a prospective study to determine the incidence of missed, potentially toxic acetaminophen poisoning in all patients with any type of intentional drug ingestion presenting to two large, county hospital emergency departments. Of 486 patients with drug ingestion seen during a five-month period, 114 (23.5%) were suspected of having ingested acetaminophen. Of these, 71 (62.3%) had insignificant acetaminophen levels (false-positive history). Of the 365 patients who were not suspected of having acetaminophen ingestion, seven patients (1.9%) were found to have elevated levels on rapid screening (false-negative history). Of these, only one patient had a potentially hepatotoxic level. We conclude that the incidence of missed, potentially serious acetaminophen overdose is very low in our study population.

Acetaminophen↗
PubMed1989

Effects of atrial natriuretic factor on isolated arteries and perfused organs of trout.

Atrial natriuretic factor (ANF) increases blood pressure when injected into conscious trout [Duff and Olson, Am. J. Physiol. 251 (Regulatory Integrative Comp. Physiol. 20): R639-R642, 1986]. The effects and mechanisms of action of ANF on trout vessels in vitro were examined in the present study using isolated celiacomesenteric arterial rings, perfused gill arches, and a two-artery perfused trunk preparation. In all experiments, ANF alone either relaxed trout vessels or had no effect. ANF inhibited contractions of arterial rings produced by a variety of agonists in part through inhibition of intracellular calcium release. In perfused gills, ANF attenuated epinephrine (EPI) alpha-mediated vasoconstriction but had no effect on beta-stimulated increases in water permeability. ANF only slightly lowered an EPI-induced increase in resistance in either pathway of the perfused trunk. These results indicate that the vascular effects and mechanism of action of ANF are similar in fish and mammals and that the pressor response to ANF injection in vivo is mediated through central or secondary effects.

Animals↗
PubMed1989

Response of rainbow trout to constant-pressure and constant-volume hemorrhage.

Plasma oncotic pressure (OC), protein concentration (P), osmolality (Osm), and hematocrit (Hct) were measured in conscious rainbow trout subjected to 120 min of constant-pressure (CPH) or constant-volume (CVH) hemorrhage. Blood volume, tissue red cell, and plasma space were determined in control and CPH trout with 51Cr-labeled red cells and 125I-albumin. At the onset of CPH, blood loss exceeded 1.5 ml.min-1.kg-1 but quickly dropped to a constant rate of 0.1 ml.min-1.kg-1 by 15 min. After 2 h, 73% of the initial blood volume was lost, and Hct, OC, and P were reduced by 55 +/- 3, 39 +/- 4, and 19 +/- 9%, respectively; Osm did not change. Calculated blood volume was reduced by 39% (51Cr method) or by 56% (125I method). Red cell space was reduced in all tissues except brain. Plasma space decreased in stomach, increased in liver and kidney, and was unchanged in other tissues. CVH had similar effects on Hct, OC, and P, while Osm and plasma sodium increased. The time required for arterial pressure to recover to within 90% of control increased with successive bleeding from 39 to greater than 160 min. Twenty-four hours after CVH, Hct remained depressed, while all other parameters were returning toward control levels. Trout incorporate a variety of mechanisms to respond to hemorrhage, including mobilization of stored blood and reabsorption of fluid from interstitial and probably intracellular sources. High permeability of trout capillaries to protein may facilitate the restoration of protein and fluid and allow fish to survive extensive hypovolemia.

Animals↗
PubMed1987

Angiotensin-converting enzyme in organs of air-breathing fish.

Angiotensin-converting enzyme (ACE) was measured in tissue homogenates from the African lungfish and six species of air-breathing teleosts (Heteropneustes fossilis, Clarias batrachus, Channa gachua, Anabas testudineus, Notopterus chitala, and Monopterus cuchia) using a standard spectrophotometric assay. In most species, the highest levels of ACE activity were found in the respiratory organs (gills and/or accessory respiratory organs). ACE was also found in heart and kidney tissues from most species and occasionally in liver. Converting enzyme was not found in skin or skeletal muscle from any species and only in blood from H. fossilis and brain from C. batrachus. Captopril, a potent inhibitor of mammalian ACE, inhibited enzymatic activity from all tissues except C. gachua heart and liver and A. testudineus heart. As fish make the transition from aquatic to aerial respiration the gill microcirculation is usually reduced in size and the accessory respiratory organs become elaborated and occupy a more central position in the vascular tree. The presence of ACE in accessory respiratory organs of air-breathing fish appears to greatly enhance the metabolic efficiency of this enzyme on circulating substrates.

Animals↗
PubMed1987

Blood volume and red cell space in tissues of the rainbow trout, Salmo gairdneri.

1. Whole body blood volume and red cell space of 22 tissues were measured in unanesthetized rainbow trout at 4, 12, 30, 60, 150 and 240 min after dorsal aortic injection of 51Cr-labeled red blood cells. 2. Apparent blood volume decreased during the initial 30 min after injection and increased thereafter. At 240 min the blood volume was 33.5 +/- 3.1 ml/kg body wt. 3. Tissue red cell space varied as a function of the interval between labeled red cell injection and tissue collection. Red cell space was highest in spleen followed by heart, kidney and liver. Lowest red cell spaces were found in stomach and red and white skeletal muscle. 4. Variability in blood volume and tissue red cell space over time suggests that caution should be exercised in the design of experiments that employ indicator dilution measurements to measure vascular volumes.

Animals↗
PubMed1986

Gill microcirculation of the air-breathing climbing perch, Anabas testudineus (Bloch):relationships with the accessory respiratory organs and systemic circulation.

The general macrocirculation and branchial microcirculation of the air-breathing climbing perch, Anabas testudineus, was examined by light and scanning electron microscopy of vascular corrosion replicas. The ventral aorta arises from the heart as a short vessel that immediately bifurcates into a dorsal and a ventral branch. The ventral branch distributes blood to gill arches 1 and 2, the dorsal branch to arches 3 and 4. The vascular organization of arches 1 and 2 is similar to that described for aquatic breathing teleosts. The respiratory lamellae are well developed but lack a continuous inner marginal channel. The filaments contain an extensive nutritive and interlamellar network; the latter traverses the filament between, but in register with, the inner lamellar margins. Numerous small, tortuous vessels arise from the efferent filamental and branchial arteries and anastomose with each other to form the nutrient supply for the filament, adductor muscles, and arch supportive tissues. The efferent branchial arteries of arches 1 and 2 supply the accessory air-breathing organs. Arches 3 and 4 are modified to serve primarily as large-bore shunts between the dorsal branch of the ventral aorta and the dorsal aorta. In many filaments from arches 3 and 4, the respiratory lamellae are condensed and have only 1-3 large channels. In some instances in arch 4, shunt vessels arise from the afferent branchial artery and connect directly with the efferent filamental artery. The filamental nutrient and interlamellar systems are poorly developed or absent. The respiratory and systemic pathways in Anabas are arranged in parallel. Blood flows from the ventral branch of the ventral aorta, through gill arches 1 and 2, into the accessory respiratory organs, and then returns to the heart. Blood, after entering the dorsal branch of the ventral aorta, passes through gill arches 3 and 4 and proceeds to the systemic circulation. This arrangement optimizes oxygen delivery to the tissues and minimizes intravascular pressure in the branchial and air-breathing organs. The efficiency of this system is limited by the mixing of respiratory and systemic venous blood at the heart.

Air↗
PubMed1986

Morphology and vascular anatomy of the accessory respiratory organs of the air-breathing climbing perch, Anabas testudineus (Bloch).

The vascular organization and endothelial cell specialization of the air-breathing organs of Anabas testudineus were examined by light and scanning electron microscopy of fixed tissue and vascular corrosion replicas. The vessels supplying blood to the lining of paired suprabranchial chambers and the plicated labyrinthine organs within the chambers are tripartite, having a median artery and paired, lateral veins. Hundreds of respiratory islets, the functional units of gas exchange, cover the surfaces of both the chamber and labyrinthine organ. A median islet artery supplies the central aspect of each islet and gives rise to numerous short arterioles from which the transverse channels are formed. Transverse channels are parallel capillary-sized vessels that extend in two rows away from the medial arterioles and drain laterally into one of two lateral islet veins. Basally situated single rows of endothelial cells lining the transverse channels form thick, evaginated, tongue-like cytoplasmic processes that project freely into the lumen from the tissue side of the channel. Other thin, septate, cytoplasmic extensions of the same cells form valve-like septa that extend across the channel. Both the septa and tongue-like processes appear to direct the red blood cells to the epithelial side of the channel and thus decrease the diffusion distance between the air and red cell. A large sinusoidal space lies under the transverse channels and may support the channels and even elevate them during increased oxygen demand. The epithelium covering the transverse channels is smooth, which enhances air convection and minimizes unstirred layer effects. The epithelium between the channels contains microvilli that may serve to trap bacteria or particulates and to humidify the air chambers.

Air↗
PubMed1986

Farm stressors.

The first section of this paper examines stressors in farm environments. The literature discussed concerns questionnaire surveys of general farm stressors, familial stressors in farm environments, such as role incongruence and conflict, and extrafamilial farm stressors. The discussion of extrafamilial stressors emphasizes financial stressors and the current farm financial crisis. Based on the implications of the farm stressor literature, the second section of the paper considers directions that community psychologists and others might take in working in farm areas. These directions are considered in terms of different types of programs aimed at preventing or alleviating farm financial stress.

Agriculture↗
PubMed1986

Acute massive digoxin overdose: survival without use of digitalis-specific antibodies.

Acute massive digoxin overdose may result in life-threatening arrhythmias, with reported mortality of up to 20% prior to the introduction of digitalis-specific antibodies. Digitalis-specific Fab antibody fragments remain under experimental protocol and are not widely available. Interpretation of serum digoxin levels and indications for the use of Fab are not clearly established. The authors report a case of massive digoxin overdose in an 18-month-old child with the highest reported digoxin level (48 ng/ml) with which a victim survived without the need for Fab administration. She developed only mild manifestations of digitalis intoxication, and her serum potassium never exceeded 5.2 mEq/l. Her course may be explained by the distribution kinetics of digoxin, which follows a two-compartment model, and the relative resistance of children to digitalis intoxication. This case emphasizes the need for better criteria than the digoxin level for the administration of Fab. The serum potassium concentration, which is usually elevated in acute type digitalis intoxication, may be a better predictor of the need for Fab in acute massive digitalis ingestion.

Digoxin↗