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Biomedical subjects

J M Russell

Publications and source records attributed to J M Russell.

At least 145 records · Page 8Linked to original sources
PubMed1975

Subpopulations of lymphocytes: a review.

Human lymphocytes comprise a heterologous population of cells which can be sub-divided on functional criteria or on the basis of surface membrane markers. Although it is widely accepted that human lymphocytes are broadly divisible into thymus dependent (T) and thymus independent (B) cells, recent evidence suggests that at least in humans this distinction may not be as clear cut as previously thought. An assessment of the relative numbers of T and B cells in human peripheral blood and lymphoid tissues can be made utilizing these marker systems. This has led to a reclassification of human lymphoid diseases according to the T and B cell concept, which might be of value in characterising the immunological status in health and disease, and may allow a more rational approach to the therapy of immune deficiency states and lymphoid malignancies.

Agammaglobulinemia↗
PubMed1974

Calcium efflux from barnacle muscle fibers. Dependence on external cations.

Calcium-45 was injected into single giant barnacle muscle fibers, and the rate of efflux was measured under a variety of conditions. The rate constant (k) for (45)Ca efflux into standard seawater averaged 17 x 10(-4) min(-1) which corresponds to an efflux of about 1-2 pmol/cm(2).s. Removal of external Ca (Ca(o)) reduced the efflux by 50%. In most fibers about 40% of the (45)Ca efflux into Ca-free seawater was dependent on external Na (Na(o)); treatment with 3.5 mM caffeine increased the magnitude of the Na(o)-dependent efflux. In a few fibers removal of Na(o), in the absence of Ca(o), either had no effect or increased k; caffeine (2-3.5 mM) unmasked an Na(o)-dependent efflux in these fibers. The Na(o)-dependent Ca efflux had a Q(10) of about 3.7. The data are consistent with the idea that a large fraction of the Ca efflux may be carrier-mediated, and may involve both Ca-Ca and Na-Ca counterflow. The relation between the Na(o)-dependent Ca efflux and the external Na concentration is sigmoid, and suggests that two, or more likely three, external Na(+) ions may activate the efflux of one Ca(+2). With a three-for-one Na-Ca exchange, the Na electrochemical gradient may be able to supply sufficient energy to maintain the Ca gradient in these fibers. Other, more complex models are not excluded, however, and may be required to explain some puzzling features of the Ca efflux such as the variable Na(o)-dependence.

Animals↗
PubMed1972

Active transport of potassium and chloride in an identifiable molluscan neuron.

Direct measurements of intracellular K(+) and Cl(-)activities before and after blockage of cellular metabolic processes indicate that K(+) is actively transported inwardly and Cl(-)is actively transported outwardly from the giant cell of the abdominal ganglion of Aplysia. The rewarming of cells that have been cooled to 1 degrees +/- 1 degrees C causes K(+) to be taken up and Cl(-) to be extruded against electrochemical gradients.

Animals↗
PubMed1972

Active transport of chloride by the giant neuron of the Aplysia abdominal ganglion.

Internal chloride activity, a(i) (Cl), and membrane potential, E(m), were measured simultaneously in 120 R2 giant neurons of Aplysia californica. a(i) (Cl) was 37.0 +/- 0.8 mM, E(m) was -49.3 +/- 0.4 mv, and E(Cl) calculated using the Nernst equation was -56.2 +/- 0.5 mv. Such values were maintained for as long as 6 hr of continuous recording in untreated neurons. Cooling to 1 degrees -4 degrees C caused a(i) (Cl) to increase at such a rate that 30-80 min after cooling began, E(Cl) equalled E(m). The two then remained equal for as long as 6 hr. Rewarming to 20 degrees C caused a(i) (Cl) to decline, and E(Cl) became more negative than E(m) once again. Exposure to 100 mM K(+)-artificial seawater caused a rapid increase of a(i) (Cl). Upon return to control seawater, a(i) (Cl) declined despite an unfavorable electrochemical gradient and returned to its control values. Therefore, we conclude that chloride is actively transported out of this neuron. The effects of ouabain and 2,4-dinitrophenol were consistent with a partial inhibitory effect. Chloride permeability calculated from net chloride flux using the constant field equation ranged from 4.0 to 36 x 10(-8) cm/sec.

Acetylcholine↗
PubMed1972

Active transport of potassium by the giant neuron of the aplysia abdominal ganglion.

We measured the internal potassium activity, a(i) (K), and membrane potential, E(m), simultaneously in 111 R2 giant neurons of Aplysia californica. a(i) (K) was 165.3 +/- 3.4 mM, E(m) was -47.8 +/- 0.9 mv, and E(K) calculated using the Nernst equation was -76.9 +/- 0.05 mv. Such values were maintained for as long as 6 hr of continuous recording in untreated cells, a(i) (K) fell exponentially after the following treatments: cooling to 0.5 degrees -4 degrees C, ouabain, zero external potassium, 2,4-dinitrophenol, and cyanide. The effects of cooling and zero potassium were reversible. Potassium permeability was calculated from net potassium flux using the constant field equation and ranged from 2.6 to 18.5 x 10(-8) cm/sec. We conclude that potassium is actively transported into this neuron against a 30-40 mv electrochemical gradient.

Animals↗
PubMedDate not supplied

HIV infection: a retrospective analysis of adolescent high-risk behaviors.

INTRODUCTION: The purpose of this study was to retrospectively ascertain behaviors and activities that may constitute high risk during the adolescent years (ages 12-18) of young adults (ages 20-25) who are infected with human immunodeficiency virus (HIV). METHODS: Subjects (n = 44) from 1 of 5 clinics in a large midwestern city completed a survey form, developed by the investigators, which examined 6 areas of behavior and activities that the literature suggested may be associated with high-risk behaviors. RESULTS: The adolescent high-risk profile of an HIV-infected young man includes sexual abuse before the age of 12 years, heavy consumption of alcohol, heavy consumption of a variety of illicit drugs, a wide variety of sexual experiences at very young ages, and multiple sexual partners. The adolescent high-risk profile of an HIV-infected young woman in this study includes heavy consumption of alcohol, heavy consumption of a variety of illicit drugs, and unprotected vaginal intercourse at very young ages as evidenced by a high number of sexually transmitted diseases at very young ages. DISCUSSION: Although the small number of participants in this study restricts interpretation of the results, adolescent health initiatives should be examined in light of these findings. Programs and services must consider the context of psychosocial situations, as well as past experiences, and incorporate this knowledge into prevention strategies.

Adolescent↗
PubMedDate not supplied

Relationships among preference for educational structure, self-directed learning, instructional methods, and achievement.

The purpose of this study was to generate information about possible relationships among preference for education structure (eg, high or low educational structure), self-directed learning, instructional methods (lecture or module), and achievement. The study was designed to use both the difference and correlation model to analyze these variables. The difference model is a 2 x 2 randomized block posttest-only design. Five research questions guided the study. It was found that (1) there was a statistically significant inverse linear relationship between preference for educational structure and self-directed learning (r = -.3081, P = .027); (2) there was no relationship between self-directed learning and achievement (P = .24); (3) neither of the instruments could successfully predict achievement (R2 = .12), but the direction of the prediction was other than expected; (4) students who preferred high structure had no statistically significant differences in achievement in either instructional method (t = -.53, P = .60), although the direction of the difference was of interest; and (5) students who preferred low structure had no statistically significant differences in achievement in either instructional method (t = 1.75, P = .099), although here too the direction of the difference was of interest. The unexpected outcomes in this study were opposite to what has been found in the literature and assumed for years.

Adult↗
PubMedDate not supplied

Comparing SSRI treatment costs for depression using retrospective claims data: the role of nonrandom selection and skewed data.

BACKGROUND AND OBJECTIVES: Since conventional randomized clinical trials often do not reflect the real world circumstances of prescribing behavior and patient outcomes, the use of retrospective administrative claims databases (RACD) has become more common in treatment cost comparisons among alternative pharmaceutical compounds. Several recent RACD studies have compared treatment costs for depressed patients prescribed SSRIs such as fluoxetine, sertraline and paroxetine. These cost comparisons have reached mixed conclusions. To begin to explain and reconcile the mixed SSRI cost comparison evidence, we undertake a variety of alternative multivariate analyses using a publicly available RACD. METHODS AND DATA: The 1995 to 1996 data encompasses a time period when all three SSRIs had become well-established agents. We report and compare results from multivariate linear regressions, logistic regressions, ordered probits and sample selectivity models, and examine robustness when adjustments are made for outlier observations and skewed distributions. RESULTS AND CONCLUSIONS: While choice of initial SSRI is nonrandom, the effect of sample selectivity on total depression-related and total health care expenditure is neutral across SSRIs. Although most cost measures are numerically greatest for fluoxetine, depression-related outpatient and hospitalization costs do not significantly differ by choice of initial SSRI. These findings are robust to alternative assumptions, specifications, and procedures. Antidepressant medication costs, however, are significantly higher when fluoxetine is the initial SSRI rather than sertraline or paroxetine, reflecting the larger proportion of fluoxetine patients prescribed a daily dosage of two or more capsules. Both total depression-related and total health care log-transformed costs are significantly lower for sertraline than fluoxetine.

Adult↗
PubMedDate not supplied

Path analysis of family resemblance for cranio-facial traits in Andhra Pradesh nuclear families and twins.

Path analysis of 12 cranio-facial measurements from a sample of nuclear families and twins from Andhra Pradesh, India is used to test hypotheses about the familial transmission of these traits. For bigonial breadth and ear dimensions, the transmission from parent to child is consistent with simple autosomal polygenic inheritance, but length, breadth and circumference of the head, facial breadth and nose dimensions show evidence of transmission in excess of polygenic expectations. Additional non-transmissible resemblance of sibling pairs is not significant for any of the variables, but twin pairs do exhibit significant additional resemblance for head circumference, head length, minimum frontal breadth, bizygomatic breadth and ear dimensions. The effect of interobserver measurement differences can be detected for head breadth, minimum frontal breadth, bigonial breadth, total facial height and nose dimensions.

Adolescent↗
PubMedDate not supplied

HIV infected women and women's services.

HIV/AIDS is increasing faster in women than any other segment in the population. The typical woman who is HIV infected is young, poor, a minority, and in the childbearing stage of life. Only 1 study was found that explored medical services in relation to usage and cost by men and women infected with HIV (F.J. Hellinger, 1993). The purpose of this study was to examine the types of services and the groupings of those services within facilities that were offered for women who were HIV positive. Seventeen of the 28 facilities (61%) that provide care to this population responded to a telephone survey. The research suggests that care for women who are HIV positive is fragmented, and there are access barriers to care and support. Many services that are especially important to HIV-infected women were not found or were not made available by many facilities.

Acquired Immunodeficiency Syndrome↗