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Biomedical subjects

K R Olson

Publications and source records attributed to K R Olson.

At least 127 records · Page 7Linked to original sources
PubMed1982

Blood flow in the rectal gland of Squalus acanthias.

The percent of cardiac output distributed to the rectal gland of 33 free-swimming fish was quantitated by the isotopically labeled microsphere technique. In 21 fish less than 1% was found in the rectal gland; 12 fish had 2-7%, suggesting a pattern of intermittent blood flow. Methylmethacrylate corrosion casts were made for scanning electron microscopy study of the microvasculature. Blood entering the rectal gland artery is distributed via three pathways. The most extensive is along the rectal gland artery into 11 or 12 circumferential vessels, which branch along the capsule and give rise to the radially arranged sinusoids that perfuse the secretory tubules and then join to form the central rectal gland vein. A second is an arterial bypass that runs the length of the rectal gland and joins the circulation of the postvalvular intestine. The third is via arteriovenous anastomoses in the capsule between tightly packed small arteries and veins. The low to moderate blood flow in most rectal glands and the very high flow in others is consistent with the observation that in vivo the rectal gland secretes only intermittently. Blood pathways allowing bypass of the rectal gland parenchyma suggest a role of blood flow in the regulation of the secretory process.

Animals↗
PubMed1982

Amanita phalloides-type mushroom poisoning.

In the fall of 1981 the San Francisco Bay Area Regional Poison Control Center received more than 100 calls regarding wild mushroom ingestion. Ten cases, including three fatalities, had all the features of Amanita phalloides poisoning. Encephalopathy, coma and renal insufficiency occurred in all three patients who died, but did not occur in those who survived. Two of the three patients who died arrived at the hospital late in the course of their illness, and severe gastroenteritis with accompanying dehydration probably contributed to their deaths. The poison control center promoted public awareness of the mushroom hazard through newspaper and television stories and by notifying local health departments. It also has devised a simple form to improve the quality of data collection and to assist in later verification of suspected A phalloides poisoning.

Adolescent↗
PubMed1981

Vascular corrosion replicas of chemo-baroreceptors in fish: the carotid labyrinth in Ictaluridae and Clariidae.

Scanning electron microscopy of vascular corrosion replicas and light microscopy revealed a pair of highly vascularized tissues, the carotid labyrinths, in the dorsal head region of the channel catfish, Ictalurus punctatus, the black bullhead, I. melas, and the walking catfish, Clarias batrachus. The labyrinth consists of a myriad of arterioles that arise from the common carotid artery immediately distal to the origin of the common carotid from the efferent branchial (epibranchial) artery of the first gill arch. The arterioles anastomose with each other to form: (1) the internal carotid artery which supplies the brain, and (2) several anteriolateral arteries that extend into the anterior head. In the ictalurids the common carotid artery emerges from the labyrinth intact and continues anteriorly as the large olfactory artery, whereas in Clarias all postlabyrinthine vessels result from arborization of the common carotid and subsequent anastomosis of the arterioles. Similarities between piscine and amphibian carotid labyrinths and the anatomical proximity of the former with the gills suggest that, in Ictaluridae, the labyrinth has a chemo- or baroreceptor function.

Animals↗
PubMed1981

Morphology and vascular anatomy of the gills of a primitive air-breathing fish, the bowfin (Amia calva).

The morphology of the gills of a primitive air breather (Amia calva) was examined by light microscopy of semithin sections of gill filaments, and gill perfusion pathways were identified by scanning-electron microscopic analysis of corrosion replicas prepared by intravascular injection of methyl methacrylate. The arrangement of gill filaments and respiratory lamellae is similar to that ot teleosts with the exception of an interfilamental support bar that is fused to the outer margins of lamellae on adjacent filaments. The prebranchial vasculature is also similar to that of teleosts, whereas the postbranchial circulation of arches III and IV is modified to permit selective perfusion of the air bladder. Gill filaments contain three distinct vascular systems: (1) the respiratory circulation which receives the entire cardiac output and perfuses the secondary lamellae; (2) a nutrient system that arises from the postlammelar circulation and perfuses filamental tissues; (3) a network of unknown function consisting of subepithelial sinusoids surrounding afferent and efferent margins of the filament and traversing the filament beneath the interlamellar epithelium. Prelamellar arteriovenous anastomoses (AVAs) are rare, postlammelar AVAs are common especially at the base of the filament where they form a dense network of small tortuous vessels before coalescing into a large filamental nutrient artery. Unlike in most teleosts, the outer vascular margins of the lamellae are embedded in the interfilamental support bar and become the sole vasculature of this tissue. Arterial-arterial lamellar bypass vessels were not observed. Previously observed decreases in oxygen transfer across the gills during air breathing can be explained only by redistribution of blood flow between or within the respiratory lamellae.

Animals↗
PubMed1980

The microvasculature of the elasmobranch gill.

Corrosion replicas were made of the gill vasculature of the spiny dogfish shark (S. acanthias) and little skate (R. erinacea) by methylmethacrylate perfusion via the ventral or dorsal aorta at 2.0-5.3 kPa. After tissue maceration the replicas were examined by light and scanning electron microscopy. In both species 3 vascular pathways were found: (1) the major pathway subserving the respiratory function of the gill, consisting of the afferent filamental artery which feeds into a medial afferent sinus (MA) from which arise the prelamellar arterioles (AL) leading to the lamellae, the postlamellar arterioles and efferent filamental artery (EA); (2) a nutrient circulation arising from the EA, supplying oxygenated blood to the filamental tissue, and anastomosing with the interlamellar vessels (IL); (3) a collateral circulation consisting of ILs which drain through channels interdigitating with the ALs and which then form a collateral reticulum, beneath the water channel epithelium, with vessels from the adjacent filaments. In the dogfish, small prelamellar arteriovenous anastomoses (PA) connect the MAs to the ILs with the same frequency as the ALs. PAs have not been found in the skate, but the efferent nutrient circulation is much more extensively developed. Many similarities exist between the elasmobranchs and teleosts in regard to the microvascular organization of the gill.

Animals↗
PubMed1980

Application of corrosion casting procedures in identification of perfusion distribution in a complex microvasculature.

The effects of vasoactive molecules on perfusion distribution within the microvasculature of the fish gill filament was examined by scanning electron microscopic analysis of methyl methacrylate corrosion casts. Gills from the channel catfish, (Ictalurus punctatus) were preperfused with a Ringer solution containing either epinephrine (10(-5)M), acetylcholine (10(-6) or 10(-8)M) or sodium nitroprusside (10(-5)M). The preperfusion was followed immediately by the methyl methacrylate resin, Mercox. All perfusion was done at physiological pressures. Epinephrine increased filling of the respiratory vasculature and favored central filamental filling on the efferent side of the filament. Acetylcholine at high doses (10(-6)M) greatly decreased respiratory vessel filling and favored filling of the central vessels on the afferent side. At low doses (10(-8)M) acetylcholine reduced respiratory filling and greatly increased methacrylate filling of the central filamental vessels. Nitroprusside decreased resin in both respiratory and central filament vessels. Sphincter like constrictions in the corrosion replicas identified vasoactive sites in acetylcholine perfused gills. The results demonstrate the applicability of this technique in identification of perfusion regulation in a complex, multifunctional vascular bed. Possible sources of error of this technique include vasostimulation by methyl methacrylate and viscosity effects.

Acetylcholine↗
PubMed1979

Vascular organization of the catfish gill filament.

Light and scanning electron microscopic observations were made on methyl-methacrylate corrosion casts of the blood vessels in the gills of channel catfish (Ictalurus punctatus). The vasculature of the gill filament can be divided into three distinct pathways: 1. the well-known respiratory circulation which includes the afferent filamental artery (AF), afferent lamellar arteriole (AL), lamella (L), efferent lamellar arteriole (EL) and efferent filamental artery (EF), 2. a nutritive pathway from the EF through small nutritive capillaries (NC) and into one of several filamental veins (FV), and 3. an interlamellar circulation in which small prelamellar arterio-venous anastomoses (PAVA) connect the AL into a series of organized vascular spaces (interlamellar vessels, ILV's) that underlie the interlamellar filamental epithelium. Several sinus like spaces associated with AF, EF and the filamental cartilagenous support were also observed. The physiological significance of these vascular pathways is discussed.

Animals↗
PubMed1978

Correlates of alcohol arrests in a rural state.

Arrest and conviction rates for public intoxication, driving while intoxicated, and liquor law violations were correlated with population, population change, liquor sales, number of law officers, Indian population, and overall crime rate for 23 counties in Wyoming. It was concluded that increased liquor sales, but not arrest rates, are associated with population increase. Alcohol arrests are related positively to population magnitude and overall crime rate, but not to number of law officers. Counties with larger Indian populations report higher arrest rates for public intoxication and liquor law violations, but conviction rates for alcohol arrests in these counties are not different.

Alcoholic Intoxication↗
PubMedDate not supplied

Physical assessment and differential diagnosis of the poisoned patient.

The rapid diagnosis and immediate intervention required in patients with serious drug overdose or poisoning makes toxicological screening of limited value to the emergency department physician. Instead, a careful clinical evaluation using the history, physical examination, and the more readily available laboratory tests may allow a tentative diagnosis and the initiation of life-saving treatment. Laboratory tests should include serum osmolality, electrolytes, glucose, BUN and an estimation of the anion and osmolar gaps. The ECG can also provide useful information. Clinical findings of important include altered blood pressure, pulse, respiration and body temperature, the presence of coma, agitation, delirium or psychosis, and muscular weakness. An ophthalmological examination is also of importance in the acutely poisoned patient. Oral burns or dysphagia may occur following ingestion of any strongly reactive substance, but the absence of oral burns does not preclude the possibility of oesophageal or stomach injury. Odours and skin colour may also contribute to the diagnosis. Comprehensive toxicology screening may not be immediately available, or may be inaccurate, thus adding little to the information obtained during the initial evaluation of the poisoned patient.

Diagnosis, Differential↗
PubMedDate not supplied

Cardiac natriuretic peptides: a physiological lineage of cardioprotective hormones?

Vertebrate hearts from fish to mammals secrete peptide hormones with profound natriuretic, diuretic, and vasodilatory activity; however, the specific role of these cardiac natriuretic peptides (NPs) in homeostasis is unclear. NPs have been suggested to be involved in salt excretion in saltwater teleosts, whereas they are proposed to be more important in volume regulation in mammals. In this review, we consider an alternative (or perhaps complementary) function of NPs to protect the heart. This hypothesis is based on a number of observations. First, evidence for NPs, or NP-like activity has been found in all vertebrate hearts thus far examined, from osmoconforming saltwater hagfish to euryhaline freshwater and saltwater teleosts to terrestrial mammals. Thus the presence of cardiac NPs appears to be independent of environmental conditions that may variously affect salt and water balance. Second, cardiac stretch is a universal, and one of the most powerful, NP secretagogues. Furthermore, stretch-induced NP release in euryhaline teleosts appears relatively independent of ambient salinity. Third, excessive cardiac stretch that increases end-diastolic volume (EDV) can compromise the mechanical ability of the heart by decreasing actin-myosin interaction (length-tension) or through Laplace effects whereby as EDV increases, the wall tension necessary to maintain a constant pressure must also increase. Excessive cardiac stretch can be produced by factors that decrease cardiac emptying (i.e., increased arterial pressure), or by factors that increase cardiac filling (i.e., increased blood volume, increased venous tone, or decreased venous compliance). Fourth, the major physiological actions of cardiac NPs enhance cardiac emptying and decrease cardiac filling. In fish, NPs promote cardiac emptying by decreasing gill vascular resistance, thereby lowering ventral aortic pressure. In mammals a similar effect is achieved through pulmonary vasodilation. NPs also decrease cardiac filling by decreasing blood volume and increasing venous compliance, the latter producing a rapid fall in central venous pressure. Fifth, the presence of NP clearance receptors in the gill and lung (between the heart and systemic circulation) suggest that these tissues may be exposed to considerably higher NP titers than are systemic tissues. Thus, a decrease in outflow resistance immediately downstream from the heart may be the first response to increased cardiac distension. Because the physiology of cardiac NPs is basically the same in fish and mammals, we propose that the cardioprotective effects of NPs have been well preserved throughout the course of vertebrate evolution. It is also likely that the cardioprotective role of NPs was one of the most primordial homeostatic activities of these peptides in the earliest vertebrates.

Animals↗