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Biomedical subjects

M F Wilson

Publications and source records attributed to M F Wilson.

At least 109 records · Page 6Linked to original sources
PubMed1981

Effectiveness of steroid/antibiotic treatment in primates administered LD100 Escherichia coli.

Early aggressive therapy with maintenance infusions of methylprednisolone sodium succinate and gentamicin sulfate significantly increases the probability for survival of baboons given LD100 Escherichia coli. The present study was designed to determine if baboons would recover when initiation of treatment was delayed until they had sustained E. coli-induced systemic hypotension for a period of approximately three hours. Sixteen adult baboons were each administered a two-hour infusion of LD100 E. coli. All eight untreated animals died within 42 hours. Five of the eight baboons treated after approximately three hours of hypotension with methylprednisolone sodium succinate and gentamicin sulfate survived. Treated animals had significantly higher blood glucose and insulin levels and lower blood urea nitrogen concentrations than baboons receiving E. coli alone. E. coli blood concentrations were lower in the treated than in the untreated baboon group by the sixth hour (less than 0.02). Heart rates increased in all animals but were not as high in the treated baboons. Both groups experienced similar decreases in mean systemic arterial pressure, PCO2, base excess, leukocyte, lymphocyte, and platelet concentrations, and increases in creatinine and lactate concentrations. Data from the present study indicate that the probability of recovery from shock is significantly increased even when initiation of steroid/antibiotic therapy is postponed until baboons have experienced sustained systemic hypotension.

Animals↗
PubMed1981

Cardiac, pulmonary and neuromuscular effects of clenbuterol and terbutaline compared with placebo.

1 Cardiac, neuromuscular (tremor) and pulmonary effects of multiple single oral doses of clenbuterol (40, 60 and 80 micrograms) and terbutaline (2.5 and 5 mg) were compared with placebo in thirteen patients with reversible obstructive airways disease. 2 The percent change in the bronchodilator and neuromuscular effects of clenbuterol and terbutaline were greater than that of the cardiac activity. 3 Both drugs decreased T wave amplitude and occasionally caused J point ST segment depression. These changes were considered typical of this class of drugs and clinically insignificant. 4 While these drugs had comparable cardiac, pulmonary and neuromuscular effects, clenbuterol, at larger doses, had a higher incidence of transient headaches and nervousness.

Adult↗
PubMed1981

Elevated plasma vasopressin concentrations during endotoxin and E. coli shock.

Plasma vasopressin concentrations, measured by radioimmunoassay, were remarkably elevated during endotoxin and E. coli shock. The concentrations were often above 500 pg/ml in dogs and above 300 pg/ml in baboons; they reached 1200 pg/ml in two dogs and 1800 pg/ml in another. Plasma concentration in a quiet, hydrated subject is 4 pg/ml; osmoregulation is maximally effective at 20 pg/ml. Elevation of plasma vasopressin occurred by 15 minutes after beginning infusion of endotoxin or E. coli and reached concentrations of 200-350 pg/ml with a decrease in cardiac output but before hypotension, which suggests decreased thoracic blood volume and decompression of left atrial stretch receptors. Even higher vasopressin levels were associated with a reduction of arterial blood pressure. The typical pattern was an early peak elevation followed by a sustained plateau of plasma vasopressin concentration in dogs and baboons with endotoxin and/or E. coli-induced circulatory shock.

Animals↗
PubMed1981

Vasopressin release during sepsis and septic shock in baboons and dogs.

Plasma vasopressin concentration was measured by radioimmunoassay in lightly anesthetized baboons and dogs before and during experimental Escherichia coli septic shock. Since vasopressin is a potent vasoconstrictor, and activator of clotting factors and a myocardial depressant, we postulated that, if found in substantial amounts in the plasma, vasopressin may contribute to the physiopathology of the septic shock syndrome. Quite high plasma vasopressin concentrations were found in both baboons and dogs. In the baboons, increased plasma vasopressin concentrations occurred, while mean arterial blood pressure was still within normal limits and remained elevated for as long as 12 hours during septic shock. Plasma vasopressin concentrations of this magnitude have been previously reported only with direct hypothalamic stimulation or after hypotensive shock secondary to hemorrhage.

Animals↗
PubMed1980

Mechanisms of impaired cardiac function by vasopressin.

The mechanisms by which elevated levels of vasopressin (ADH) in man and animals cause serious myocardial dysfunction, evidenced by arrhythmias, reduction in cardiac output and coronary blood flow, are not settled. Experiments were conducted in 16 isolated working left ventricles to examine their metabolic and hemodynamic responses to the infusion of vasopressin and the combination of vasopressin and epinephrine. Contractile performance was evaluated by analysis of positive dP/dt, contractile element velocities, and ventricular work-curves using stroke work/end-diastolic pressure. Relaxation parameters, including negative dP/dt and the early diastolic relaxation time constant, were also studied. Coronary blood flow was reduced 22% or less by vasopressin while cardiac output was maintained at a constant level. Myocardial oxygen consumption, lactate and potassium balances were determined from arterial and coronary sinus concentrations. Vasopressin produced myocardial dysfunction indicated by decrements in contractile and relaxation indices, without evidence of global ischemia. Epinephrine restored the mechanical performance to normal without significant change in coronary blood flow, myocardial oxygen consumption, or lactate and potassium balance.

Animals↗
PubMed1980

Reduced left ventricular hypertrophy following long-term water deprivation in the young spontaneously hypertensive rat.

Biochemical and physical parameters of cardiac hypertrophy accompanying hypertension were studied in water deprived versus non-deprived immature spontaneously hypertensive rats (SHR) and their normotensive progenitor strain, Wistar Kyoto (WKY). A 23.5 hour/day water deprivation schedule was maintained from 5 to 13 weeks of age in 23 SHR and 8 WKY rats to compare the non-deprived animals (16 SHR and 8 WKY controls). Water deprived SHR had lower left ventricular weight, lower total protein and hydroxyproline and the same total DNA as the non-deprived SHR. DNA concentration was higher in the deprived SHR than in the non-deprived SHR. No differences were found among the four groups in right ventricular weight or DNA concentration. Left to right ventricular weight ratio was significantly lower and left to right ventricular DNA concentration ratio significantly higher in the deprived SHR relative to non-deprived SHR. These data indicate that the water deprived SHR, which was less hypertensive than the non-deprived SHR, had less hypertrophy of their left ventricles. While water deprivation lowered mean arterial pressure in the WKY, also, there was no effect on left ventricular weight or biochemical indices of left ventricular cell size and cell number.

Animals↗
PubMed1977

Effects of steady-state plasma vasopressin levels on the distribution of intrarenal blood flow on electrolyte excretion.

1. In order to evaluate the effects of arginine vasopressin (AVP) on the distribution of intrarenal blood flow and on electrolyte excretion, steady-state plasma AVP levels (4-8, 19-1, 44-3, and 100-6 micro u./ml.) were produced in anaesthetized dogs, which were hydrated to minimize endogenous anti-diuretic hormone (ADH) release. 2. The urinary excretion of sodium and potassium increased without change in their filtered loads during AVP infusion. 3. Measurement by the 133xenon washout method revealed diphasic blood flow shifts, as a function of the plasma AVP level, between compartment 1 (outer cortex) and compartment 2 (inner cortex and outer medulla) without change in compartment 3 (inner medulla). 4. In a separate study, the radioactive microsphere (15 micronm) method was used with a plasma AVP levels of 19-8 micronu./ml. Blood flow (expressed as % flow/g tissue) decreased in the outer cortex and increased in the inner cortex. 5. Total renal blood flow did not change during infusion of AVP. However, the values measured by 133xenon were lower than those measured by the microsphere method. 6. There was agreement between these two independent methods that blood flow shifted from outer to inner cortex, with no change in total renal flow, at similar plasma AVP levels (19-1 and 19-8 micronu./ml.). The relationship of these intrarenal circulatory changes to the increased electrolyte excretion is discussed.

Animals↗
PubMed1976

Implantable electrode for recording nerve signals in awake animals.

An implantable electrode assembly consisting of collagen and metallic electrodes was constructed to measure simultaneously neural signals from the intact nerve and bioelectrical noises in awake animals. Mechanical artifacts, due to bodily movement, were negligibly small. The impedance of the collagen electrodes, measured in awake cats 6-7 days after implantation surgery, ranged from 39.8-11.5 komega at a frequency range of 20-5 kHz. Aortic nerve activity and renal nerve activity, measured in awake conditions using the collagen electrode, showed grouped activity synchronous with the cardiac cycle. Results indicate that most of the remal nerve activity was from postganglionic sympathetic fibers and was inhibited by the baroceptor reflex in the same cardiac cycle.

Animals↗
PubMed1975

Interactions of C-reactive protein with the complement system. II. C-reactive protein-mediated consumption of complement by poly-L-lysine polymers and other polycations.

Cationic homopolymers of poly-L-lysine were found to activate complement (C) via C-reactive protein (CRP) and deplete C3 and C5 as well as early-acting C components. Maximum C consumption was obtained with polymers of 2,000-8,000 daltons; polymers of 1,700, 11,000, and 23,000 daltons were intermediate in reactivity, while L-lysine, lysyl-L-lysine, tetra-L-lysine, and polymers of 70,000-400,000 daltons lacked significant C-consuming activity. Naturally occurring polycations which consumed C in the presence of CRP included myelin basic proteins, cationic proteins of rabbit leukocytes, and both lysine- and arginine-rich histones; poly-L-arginine polymers of 17,000 but not 65,000 daltons also were C-consuming. Polycations without such reactivity included poly-L-orithine (5,000 and 165,000 daltons), egg white and human lysozymes, and Polybrene. The polycations which failed to induce C consumption via CRP, inhibited its consumption by both active polycations and by C-polysaccharide (CPS). The relative inhibitory capacity of phosphorylcholine and polycations in CPS- and polycations-CRP systems was consistent with the concept that phosphate esters and polycations react at the same or an overlapping combining site. The ability of certain polycations to activate C via CRP increases the potential for initiation of host reactions via C. The capacity of other polycations to inhibit C activation via CRP introduces a potential for physiologic or pharmacologic manipulation. These considerations would seem to expand the potential role of CRP in the initiation and modulation of the inflammatory response.

Animals↗