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Biomedical subjects

R Rosen

Publications and source records attributed to R Rosen.

At least 73 records · Page 4Linked to original sources
PubMed1986

The effects of glucagon and metoclopramide as measured by the electrogastrogram.

The electrogastrogram, purportedly a measurement of the stomach's electrical activity, has received increased attention recently. This attention has also created skepticism because measurements are taken from the cutaneous surface. To test the electrogastrogram's ability to measure the stomach's electrical potential, we infused glucagon (0.5 mg), metoclopramide (10 and 20 mg in two sittings), and a placebo into six subjects. The electrogastrogram registered predictable changes in response to these infusions. We conclude that the electrogastrogram measures the stomach's electrical activity. Additionally, the unique data gathered by the electrogastrogram suggest that glucagon and metoclopramide both act directly on the electrical activity of gastric cells.

Double-Blind Method↗
PubMed1985

Orthostatic effect of imipramine and doxepin in depressed geriatric outpatients.

Blood pressure measurements were collected from 36 depressed geriatric outpatients (ages 55 to 81 years) enrolled in a double-blind, placebo-controlled study of the efficacy of doxepin and imipramine. Mean systolic postural changes were 25.9 mm Hg for imipramine, significantly higher than the 10.5 mm Hg for doxepin, and 12.4 mm Hg for placebo. The orthostatic drop in the imipramine group was only weakly related to dose and did not correlate with amount of pretreatment orthostatic hypotension or with duration of treatment. The increased orthostatic hypotension occurred early in treatment and at low doses of imipramine. Accordingly, caution is advised in the use of imipramine for the elderly.

Age Factors↗
PubMed1984

Experimental infections of rainbow trout, Salmo gairdneri Richardson, with plerocercoids of Triaenophorus crassus Forel.

This study concerned the suitability of rainbow trout as an experimental host for plerocercoids of Triaenophorus crassus. Twenty-five trout were exposed to Cyclops bicuspidatus thomasi infected with procercoids of T. crassus. Plerocercoids were recovered from 11 of these fish. Hemorrhaging in the muscle was the first evidence of infection in live fish between Days 22-58 postinfection (PI). Migration of worms created extensive lesions in the muscle by Day 30 PI followed by formation of granulomas between Days 45-75 PI. One to three plerocercoids were wound throughout the muscle after Day 30 PI, and penetration into the body cavity and through the integument was common. Mortality of infected trout was first observed at Day 44 PI, and by Day 56 PI, 45% of the trout died. The swimming behavior of infected trout was marked by decreased activity and loss of equilibrium.

Animals↗
PubMed1983

Subretinal neovascularization as a complication of drainage of subretinal fluid.

Four cases of subretinal choroidal neovascularization that developed at the sight of breaks in Bruch's membrane were made for the drainage of subretinal fluid during retinal reattachment surgery. This neovascularization can occur in both young and older patients. All drainage sights were posterior to the equator, which may indicate a higher risk of the development of this complication from posterior drainage sights. Unless the fovea is threatened, there is no urgency to treat this choroidal neovascularization. It is unclear why this complication is so rare, considering the frequency of surgical perforation of the choroid and Bruch's membrane during drainage of subretinal fluid in retinal reattachment surgery.

Adolescent↗
PubMed1983

Role of similarity principles in data extrapolation.

This paper addresses the problem of extrapolating from data set gathered on a particular system to problems of more general physiological interest. It asks: what are the limits of the extrapolability of data? Under what circumstances can data derived from a particular system be transformed into data about another, different system? Such questions address the general problem of similarity analysis. A mathematical exploration of the meaning and usefulness of the concept of similarity is presented, and the necessity for a "prototype" is introduced. The discussion shows what we mean by the relationship between natural systems and the purest form of model of such systems, the mathematical model. The value and limitations of Dimensional Analysis are considered. It is concluded that the principle of dimensional homogeneity which underlies Dimensional Analysis is not strong enough to cope effectively with situations involving many phases, as arise in biological studies. Therefore, a more general approach is used. It is shown that the problems associated with data extrapolation are very deep and lead to some of the deepest issues in all of science. The extrapolation of data from animal models to human beings has been a general characteristic of pharmacologic research and, for that matter, biomedical investigations generally. Attention to limitations and dangers of such extrapolations seems overdue. With proper understanding of the essential nature of the extrapolatory action, and modeling relations, models can be validated.

Animals↗
PubMed1981

A general interactive model for B cell activation. I. The theory.

A quantitative model of the B lymphocyte triggering apparatus is proposed in which mitogen receptors and surface immunoglobulins are described as allosteric proteins that interact with mitogens and antigens. An equation is derived that describes the activation of a cell as a function of the states of these receptors as defined by ligand and receptor concentrations, ligand receptor equilibrium constants, and receptor allosteric constants. We analyze the model and show that different parameter sets will actually generate a description of the one-nonspecific-signal model, the matrix model, or the two-signal model of B cell triggering. We suggest that our general interactive model provides a useful conceptual approach to studies of B cell activation because it encompasses other available models that are individually consistent with some experiments, but mutually exclusive to each other. A companion paper describes a series of experiments that verify the consistency of the general model.

B-Lymphocytes↗