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Biomedical subjects

S E Gordon

Publications and source records attributed to S E Gordon.

63 records · Page 4Linked to original sources
PubMed1990

Hormonal and growth factor responses to heavy resistance exercise protocols.

To examine endogenous anabolic hormone and growth factor responses to various heavy resistance exercise protocols (HREPs), nine male subjects performed each of six randomly assigned HREPs, which consisted of identically ordered exercises carefully designed to control for load [5 vs. 10 repetitions maximum (RM)], rest period length (1 vs. 3 min), and total work effects. Serum human growth hormone (hGH), testosterone (T), somatomedin-C (SM-C), glucose, and whole blood lactate (HLa) concentrations were determined preexercise, midexercise (i.e., after 4 of 8 exercises), and at 0, 5, 15, 30, 60, 90, and 120 min postexercise. All HREPs produced significant (P less than 0.05) temporal increases in serum T concentrations, although the magnitude and time point of occurrence above resting values varied across HREPs. No differences were observed for T when integrated areas under the curve (AUCs) were compared. Although not all HREPs produced increases in serum hGH, the highest responses were observed consequent to the H10/1 exercise protocol (high total work, 1 min rest, 10-RM load) for both temporal and time integrated (AUC) responses. The pattern of SM-C increases varied among HREPs and did not consistently follow hGH changes. Whereas temporal changes were observed, no integrated time (AUC) differences between exercise protocols occurred. These data indicate that the release patterns (temporal or time integrated) observed are complex functions of the type of HREPs utilized and the physiological mechanisms involved with determining peripheral circulatory concentrations (e.g., clearance rates, transport, receptor binding). All HREPs may not affect muscle and connective tissue growth in the same manner because of possible differences in hormonal and growth factor release.

Adult↗
PubMed1988

Breast calcifications: analysis of imaging properties.

The imaging characteristics of microcalcifications in both benign and malignant breast conditions were analyzed in 48 digitized film mammograms. Each case included in this analysis had findings considered suggestive of malignancy by the radiologist, with the underlying histologic structure determined by excisional biopsy. Imaging properties of each microcalcification--such as pixel intensity, relative location, distribution, size, and local neighborhood intensities--were recorded. This information was statistically analyzed at the population level according to such selection criteria as histologic type, size of calcification, and cluster size. Distribution ranges were determined for these criteria. Statistical differences between data from benign and malignant cases show the average distance between calcifications in malignant conditions was greater than in benign conditions, and tissue region averages surrounding calcifications associated with malignant conditions were consistently higher than those for benign conditions.

Adult↗
PubMed1986

A model of the smooth pursuit eye movement system.

Human, horizontal, smooth-pursuit eye movements were recorded by the search coil method in response to Rashbass step-ramp stimuli of 5 to 30 deg/s. Eye velocity records were analyzed by measuring features such as the time, velocity and acceleration of the point of peak acceleration, the time and velocity of the peaks and troughs of ringing and steady-state velocity. These values were averaged and mean responses reconstructed. Three normal subjects were studied and their responses averaged. All showed a peak acceleration-velocity saturation. All had ringing frequencies near 3.8 Hz and the mean steady-state gain was 0.95. It is argued that a single, linear forward path with any transfer function G(s) and a 100 ms delay (latency) cannot simultaneously simulate the initial rise of acceleration and ring at 3.8 Hz based on a Bode analysis. Also such a simple negative feedback model cannot have a steady-state gain greater than 1.0; a situation that occurs frequently experimentally. L.R. Young's model, which employs internal positive feedback to eliminate the built-in unity negative feedback, was felt necessary to resolve this problem and a modification of that model is proposed which simulates the data base. Acceleration saturation is achieved by borrowing the idea of the local feedback model for saccades so that one nonlinearity can account for the acceleration-velocity saturation: the main sequence for pursuit. Motor plasticity or motor learning, recently demonstrated for pursuit, is also incorporated and simulated. It was noticed that the offset of pursuit did not show the ringing seen in the onset so this was quantified in one subject. Offset velocity could be characterized by a single exponential with a time constant of about 90 ms. This observation suggests that fixation is not pursuit at zero velocity and that the pursuit system is turned on when needed and off during fixation.

Eye Movements↗
PubMed1981

Central osteoma of the mandible: report of case.

A case of central osteoma of the mandible in a 22-year-old woman is presented. Pain, paresthesia, and abnormal lip spasms were symptoms. Pain and paresthesia were the result of direct nerve compression, and were relieved by removal of the lesion.

Adult↗
PubMedDate not supplied

Influence of altitude and caffeine during rest and exercise on plasma levels of proenkephalin peptide F.

The purpose of this study was to examine the resting and exercise response patterns of plasma Peptide F immunoreactivity (ir) to altitude exposure (4300 m) and caffeine ingestion (4 mg.kg b.w.-1). Nine healthy male subjects performed exercise tests to exhaustion (80-85% VO2max) at sea level (50 m), during an acute altitude exposure (1 hr, hypobaric chamber, 4300 m) and after a chronic (17-day sojourn, 4300 m) altitude exposure. Using a randomized, double-blind/placebo experimental design, a placebo or caffeine drink was ingested 1 hour prior to exercise. Exercise (without caffeine) significantly (p less than 0.05) increased plasma Peptide F ir values during exercise at chronic altitude only. Caffeine ingestion significantly increased plasma Peptide F ir concentrations during exercise and in the postexercise period at sea level. Conversely caffeine ingestion at altitude resulted in significant reductions in the postexercise plasma Peptide F ir values. The results of this study demonstrate that the exercise and recovery response patterns of plasma Peptide F ir may be significantly altered by altitude exposure and caffeine ingestion. These data support further study examining relationships between Peptide F (and other enkephalin-containing polypeptides) and epinephrine release in response to these types of physiological stresses.

Adult↗
PubMedDate not supplied

Perfusion system components release agents that distort functional properties of rod cyclic nucleotide-gated ion channels.

In switching from studying native cyclic nucleotide-gated (CNG) ion channels in rod cells to studying the corresponding cloned channels expressed in Xenopus oocytes, we changed our perfusion system to a more efficient one. This change involved replacing culture flasks and a small plexiglass/glass chamber with plastic syringes, metal needles, and plastic petri dishes. We now report that these new perfusion system components release agents that distort or obscure measured functional properties of rod CNG channels. The magnitude and time course of appearance of the artifacts vary widely among individual components (e.g. from syringe to syringe). The effects most resemble voltage-dependent block of the channels, giving a decrease in current at positive potentials, and producing distortions of the kinetics and voltage dependence of channel activation.

Animals↗
PubMedDate not supplied

Development of an instrument to measure stress in the older adult.

The purpose of this study was to develop and carry out initial psychometric evaluation of a tool to measure stress in adults 65 years of age and older. The universe of stressors for this age group was elicited from 25 older adults, a literature review, and consultations with gerontological nursing experts. The stressors were ranked and weighted, using a Q-sort, by a sample of 43 adults 65 and over, resulting in the Stokes/Gordon Stress Scale (SGSS). The instrument was evaluated using reliability and validity measures. Test-retest reliability estimates yielded a Pearson's r ranging from .98 to .90. Coefficient alpha was .86. Pearson's r in a 1-year test of predictive validity was .36, p = .014; in tests of concurrent validity correlations ranged from .65 to .81. The SGSS can be used for clinical and research purposes to aid in assessing and planning care for the older individual.

Aged↗