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Biomedical subjects

S Mullen

Publications and source records attributed to S Mullen.

12 recordsLinked to original sources
PubMed2004

Determination of bull sperm membrane permeability to water and cryoprotectants using a concentration-dependent self-quenching fluorophore.

The objective of this study was to determine the membrane permeability characteristics of bovine spermatozoa. These included the hydraulic conductivity (Lp), the permeability coefficients (Ps) of four common cryoprotective agents (CPAs) and the associated reflection coefficients (sigma). Stopped-flow fluorometry was applied in order to capture rapid cell volume changes under anisosmotic conditions in the absence or presence of permeant solutes (CPAs). This technique utilizes a concentration-dependent self-quenching entrapped fluorophore. The resulting cell volume changes were used in three-parameter fitting calculations to compute Lp in the absence of permeant solutes and Ps and Lp in the presence of permeating solutes (CPAs) at 22 degrees C. The hydraulic conductivity in the absence of permeating solutes was estimated to be 0.68+/-0.05 microm/min/atm (mean+/-SEM). Hydraulic conductivity (Lp) in the presence of CPAs was 0.91+/-0.27 (mean+/-SEM), 0.29+/-0.04, 0.42+/-0.05, and 0.39+/-0.03 microm/min/atm in the presence of dimethylsulfoxide (Me(2)SO), glycerol, propylene glycol (PG), and ethylene glycol (EG), respectively. The values for Ps were estimated to be 1.72+/-0.36, 1.75+/-0.03, 2.47+/-0.24, and 1.49+/-0.33 x 10(-3)cm/min for Me(2)SO, glycerol, PG, and EG, respectively. The data were used to simulate volume excursions during addition and removal of CPA, to predict the different effects of the four CPAs.

Animals↗
PubMed2001

How covert are covertly manipulated diets?

OBJECTIVE: To quantitatively assess subjects' ability to detect hedonic (palatability), sensory and nutritional differences between covertly manipulated high-fat (HF) and low-fat (LF) diets. SUBJECTS AND DIETS: This study examined the response of 16 subjects (eight men, eight women) to 20 LF and 20 HF versions of manipulated foods. Average percentage protein:fat:carbohydrate (by energy) and energy density (ED) of the two diets were 13:25:62, 371 kJ/100 g and 13:50:37, 672 kJ/100 g, respectively. PROTOCOL: Subjects were asked to simultaneously assess the HF and LF versions of each food in terms of (i) subjective pleasantness of each food, (ii) perceived differences in appearance, smell, taste and texture of the foods, and (iii) for each sample to assess whether it was high or low in energy, protein, carbohydrate, fat, fibre, sugar and salt. ANALYSIS: Perceived pleasantness of HF and LF versions of the foods was compared by analysis of variance. Comparisons used chi-squared tests of independence to assess departure from the null hypothesis of no perceived difference in remaining parameters (ii-iii). RESULTS: On average, subjects exhibited no significant preference for LF or HF versions of the foods (no difference 15 foods, three HF foods more pleasant, two LF foods more pleasant (P<0.03)). On average there were no general differences in comparison of sensory attributes that were consistently ascribable to the LF or HF foods, although there were numerous significant differences for individual foods. Subjects appeared unable to distinguish the HF foods as being HF (66% of estimates) and guessed correctly 33% of the time. They were better able to categorize the LF foods correctly (53% correct). On aggregate 43% of HF and LF foods were correctly identified. Subjects appeared able to detect sensory differences between foods but not to relate them to energy or nutrient content of these foods. CONCLUSIONS: These data suggest that subjects are on average not able to perceive large differences in the fat content of diets manipulated in this manner. In general the assumption that the manipulation of such foods is covert appears to hold, but subjects were far better at correctly identifying certain food types (dairy-based) over others.

Adult↗
PubMed1992

Breeding kennel management.

Veterinarians and dog breeders should work together to establish protocols for health care and breeding management that are based on sound scientific principles as well as practical systems. These protocols should involve bitches, stud dogs, and puppies. Tantamount importance must be placed on record keeping so that problems may be identified and solved before they are irreversible.

Animals↗
PubMed1989

Isolated symptomatic peripheral neuropathy in type 1 insulin-dependent diabetes mellitus.

Diabetic neuropathy is probably the most frequent of the chronic complications of diabetes, and is usually found in association with diabetic retinopathy and/or nephropathy. We report seven patients with long-standing insulin-dependent diabetes mellitus in whom symptomatic peripheral neuropathy was the first and only documented complication. The diagnosis of peripheral symmetrical neuropathy was based on the presence of symptoms and abnormal physical findings, confirmed with abnormal electrophysiological and/or vibratory and thermal threshold measurements. Diabetic retinopathy and nephropathy were absent. We conclude that in some type 1 insulin-dependent diabetic patients, similar to what has been reported in type 2 non-insulin-dependent diabetes, peripheral neuropathy may be the first chronic complication to become manifest. This observation provides additional evidence to suggest that each of the diabetic complications may have a different pathogenic mechanism.

Adult↗
PubMed1988

The dual effects of ouabain on 45Ca2+ transport and contractility in adult rat ventricular myocytes.

We used isolated ventricular myocytes to study 45Ca2+ transport in the presence of three concentrations of ouabain (10 nM, 1 microM, and 100 microM) in Tyrode solution containing 1 mM CaCl2. The cells were quiescent and during 45Ca2+ uptake and 45Ca2+ efflux experiments, 10 nM ouabain decreased Ca2+ content, 1 microM, didn't change it appreciably, and 100 microM increased it significantly. Qualitatively, the same results were obtained at 22 degrees C and 35 degrees C. Ouabain did not significantly affect the electrical activity of isolated, electrically stimulated myocytes, but it increased the amplitude of shortenings of these myocytes in a dose-dependent manner. Thus, the positive inotropic effect of ouabain at therapeutic doses (less than or equal to 10 nM) occurs in spite of decreased Ca2+ content, while at high toxic doses the positive inotropic effect is accompanied by an increment in Ca2+ content. These data support the hypothesis that the mechanisms of positive inotropy of ouabain are different at therapeutic and toxic concentrations of this drug. Finally, our study demonstrates that the effects of low doses of ouabain are independent of the release of endogenous catecholamines.

Animals↗
PubMed1987

A computerized system for measuring detection sensitivity over the visual field.

A device is described for comprehensively measuring the capability of human operators to detect and react to visual signals occurring at a variety of locations throughout the functional visual field. The system is completely automated and computerized, and provides both documentation files and descriptive graphics of the operator's performance immediately upon completion of testing. Sensitivity of detection can be measured for red, yellow, and green stimulus colors in a testing configuration which mimics commonplace surveillance of the ordinary viewing field. An abbreviated listing of the main operating program software is provided.

Computer Systems↗
PubMed1979

The Comprehensive Blood Bank Survey Program of the College of American Pathologists--1977.

The 1977 CAP Comprehensive Blood Bank Survey was sent to 2487 laboratories in the United States and five foreign countries. The results show that ABO and Rh testing has a continued concurrence of greater than 94.8% between participating and referee laboratories, while antibody detection was 95.9% effective on the type problem normally encountered in a transfusion service. Cross match showed a concurrence rate of 97.3% or better. Although these testings are artificial and cannot be directly extrapolated into effectiveness of patient care, they can be compared with each other and show a standard of excellency in the laboratory which is a good or better than that found in previous studies. A series of ungraded specimens and questionnaires shows that most laboratories used a 51 degree C heat elution method for antibody elution, but slightly better results were obtained with the Rubin technic. A second study showed that the grading of a positive direct antiglobulin test was fairly reproducible throughout the country.

Antibodies↗