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Biomedical subjects

A Meier

Publications and source records attributed to A Meier.

105 records · Page 6Linked to original sources
PubMed1979

The research diagnostic criteria: historical background, development, validity, and reliability.

This article reviews the theoretical papers and research studies concerning the Research Diagnostic Criteria (RDC), a research tool used to group psychiatric sugjects into homogenous diagnostic groups. The RDC contains specified inclusion and exclusion criteria for 25 diagnostic categories. The contributions made by the Feighner and Spitzer groups in the field of diagnostic reliability and validity are briefly outlined. The development of the RDC and studies regarding its reliability and validity are presented and discussed. A review of the reliability studies, which basically employed an interrater design, indicated that the RDC is a relatively reliable diagnostic tool, obtaining interrater kappa coefficients which are consistently higher than those obtained, for similar categories, in studies using other diagnostic systems such as the DSM-II. Very few studies, however, directly investigated the validity of the RDC. Its assumed validity is dependent on the findings from studies which used similar diagnostic criteria. It was suggested that more studies would be required to establish the validity of the RDC. Several limitations of the RDC were pointed out. Included among these were: its use of an exclusion method to determine diagnostic criteria, the difficulty and great amount of time required for its use, and the fact that it has so far been used only with adult inpatients. Despite its limitations, it was concluded that the RDC remains one of the best tools available to a researcher who wishes to group psychiatric patients into homogenous groups, and that the clinician could advantageously use it in his clinical practice.

Humans↗
PubMed1976

The influence of the internal compliance of a respirator on the alveolar gas distribution.

The occurrence of intrapulmonary redistribution "pendelluft" during the plateau phase of a respirator, with and without internal compliance, was studied in a lung-model which simulated an obstructive inhomogeneity. Internal compliance was achieved by adding a flask, with a variable volume, to the patient circuit of a respirator which had a low compressible volume (Engström Care System ECS 2000, Junger Instrument AB, Sweden). The amount of redistributed volume was found to be dependent upon the internal compliance. Without additional compressible volume, the ventilator produced up to 18% redistribution which under all conditions could be brought below the 1% level when an internal compliance was introduced. A highly significant correlation between the amount of redistributed volume (pendelluft) and the discharge time-constant of the plateau (taupl = CI (RI + Rtr) could be established. The results of mathematical consideration gained from an electrical analogue coincided with our experimental findings. From this, some consequences could be derived for the design of an internal compliance for use with a respirator.

Airway Obstruction↗
PubMedDate not supplied

Effects of age and gender on the pharmacodynamics of omapatrilat in healthy volunteers.

Omapatrilat is the most clinically advanced member of a new class of cardiovascular drugs, vasopeptidase inhibitors. Omapatrilat is a single molecule that simultaneously inhibits neutral endopeptidase and angiotensin-converting enzyme, thus preserving vasodilator peptides and inhibiting production of the vasoconstrictor angiotensin II. In healthy male volunteers, omapatrilat decreased blood pressure while being generally well tolerated, with no serious adverse events. This study was undertaken to determine the effect of age and gender on the pharmacodynamics of omapatrilat. Healthy male or female volunteers between the ages of 18 and 80 were given a single oral dose of omapatrilat 40 mg. Neither age nor gender affected the vasopeptidase inhibition by omapatrilat. There were no differences between subject groups in the effect of omapatrilat on supine systolic, diastolic, or mean arterial blood pressure. Based on this study of healthy subjects, it can be concluded that it is not necessary to adjust the initial dose of omapatrilat for the treatment of hypertension based solely on age or gender.

Adolescent↗
PubMedDate not supplied

Effects of short-term norepinephrine infusion on plasma catecholamines, renin, and aldosterone in normal and hypertensive man.

The acute responsiveness of plasma catecholamine, renin (PRA), and aldosterone levels to exogenous norepinephrine was studied under placebo conditions and following renin (PRA), and aldosterone levels to exogenous norepinephrine was studied under placebo conditions and following renin-angiotensin activation by diuretic pretreatment in 25 normal subjects and 34 patients with borderline-to-moderate essential hypertension. Norepinephrine infusion caused increases in plasma norepinephrine (PNE) that correlated with the infused norepinephrine dose (p < 0.001); this relationship was similar in normal and hypertensive subjects and unaltered by diuretic therapy. Plasma epinephrine and dopamine levels were unchanged during norepinephrine infusion. Norepinephrine infusion at pressor doses stimulated PRA (p < 0.01). The PRA responses correlated with the dose of infused norepinephrine (p < 0.0025), and norepinephrine-stimulated PRA correlated with basal PRA (p < 0.001). These norepinephrine-PRA relationships were unaltered by diuretic treatment and similar in normal and hypertensive subjects. In both groups, norepinephrine also caused a similar increase in plasma aldosterone (p < 0.05) under placebo conditions, but not following diuretic therapy. These findings demonstrate that an acute increase in the blood levels of the adrenergic neurotransmittor, norepinephrine, causes mild but distinct stimulation of plasma renin and aldosterone levels. Renin release in response to exogenous norepinephrine is not enhanced following renin-angiotensin activation by diuretic pretreatment. The responsiveness of the renin-angiotensin-aldosterone system to an acute norepinephrine input seems to be intact in essential hypertension.

Adolescent↗
PubMedDate not supplied

Pressor factors and cardiovascular pressor responsiveness in borderline hypertension.

The role of various pressor factors and cardiovascular responsiveness to norepinephrine or angiotensin II in the pathogenesis of borderline hypertension was evaluated. Exchangeable body sodium, blood volume, plasma renin activity, norepinephrine or dopamine levels, and norepinephrine or epinephrine excretion rates were similar between 24 patients with borderline hypertension (mean age 34 +/- 4 (SEM) years and 22 normal subjects matched for age; the patients had a slight increase in supine plasma epinephrine. Pressor doses of norepinephrine or angiotensin II were significantly lower (p less than 0.01 and 0.001, respectively) in the borderline hypertensive group. These findings suggest that borderline hypertension may be maintained by inappropriately increased cardiovascular response to norepinephrine and angiotensin II in the presence of normal sympathetic and renin activity and a normal body sodium-volume state.

Adult↗
PubMedDate not supplied

Pressor factors and cardiovascular pressor responsiveness in lean and overweight normal or hypertensive subjects.

Several blood-pressure-regulating factors including exchangeable sodium, blood volume, plasma renin, aldosterone, norepinephrine (NE), and epinephrine (E) levels, urinary catecholamine excretion rates, and cardiovascular responsiveness to infused NE and angiotensin II (AII) were compared among age-matched subgroups of normal subjects (15 with normal weight, 15 with overweight) and patients with essential hypertension (15 with either normal weight, overweight, or obesity). Exchangeable sodium, blood volume, plasma and urinary sodium and potassium, plasma renin, aldosterone and epinephrine levels, and NE or E excretion rates did not differ significantly among the five subgroups. Minimal differences included a slightly higher heart rate in overweight patients than in overweight normal subjects (p less than 0.01) and a tendency for a higher plasma NE in overweight than in normal weight patients. Plasma NE obtained immediately before NE infusion as well as the plasma clearance of NE did not differ among the five subgroups except, however, for a somewhat low NE clearance in obese patients. The NE pressor dose tended to be lower in normal-weight hypertensive than in normal-weight normotensive subjects. No alteration was apparent in overweight or obese hypertensive patients. Pressor responses to AII were similar in the different subgroups. These findings suggest that overweight does not confer a unique aberration in the body sodium-volume state, circulating renin, aldosterone or catecholamines, or cardiovascular responses to NE or AII which result in hypertension.

Adult↗
PubMedDate not supplied

Skeletal muscle reperfusion injury: reversal by controlled limb reperfusion--a case report.

Despite successful surgical revascularization of ischemic limbs, a local and systemic reperfusion injury may occur after normal blood reperfusion. Recent experimental and clinical application of controlled limb reperfusion in Europe has demonstrated superior results, with lower morbidity and mortality. This new surgical technique includes modification of the reperfusate (calcium, pH, substrates, osmolarity, free radical scavenger) and the circumstances of initial reperfusion (time, temperature, pressure). This report describes the first application of controlled limb reperfusion after reperfusion injury. A 16-year-old boy underwent femoral access cardiopulmonary bypass for repeat cardiac repair with an ischemic time of 245 minutes. Postoperatively, severe ischemia/reperfusion syndrome developed with muscle contracture, immobility, and anesthesia of the right leg with a second ischemic time of about 6 hours. The systemic creatine phosphokinase level was 88,000 U/L; myoglobin was 27,000 ng/mL. He underwent controlled limb reperfusion by withdrawing blood from the aorta and mixing it with a crystalloid solution (calcium-reduced, hyperosmolar, hyperglycemic, alkalotic, glutamate- and aspartate-enriched, and containing a free radical scavenger) under controlled conditions (blood:crystalloid solution 6:1, for 30 minutes, reperfusion pressure < 50 mm Hg, and normothermia) before establishing normal blood reperfusion. Metabolic data from the central and femoral vein demonstrated a significant reduction of all previous elevated enzyme levels, avoidance of hyperkalemia, normalization of acidosis, and avoidance of systemic reperfusion injury with no multiorgan failure. Limb salvage was accomplished and functional recovery almost complete. To the authors' knowledge, this is the first application of controlled limb reperfusion reported in North America. With this surgical technique we were able to prevent metabolic local and systemic reperfusion changes after prolonged ischemia and also reduced previous reperfusion changes. This report confirms former experimental data, and further clinical studies are warranted.

Adolescent↗