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Biomedical subjects

S M Ross

Publications and source records attributed to S M Ross.

At least 19 recordsLinked to original sources
PubMed2004

A comparison of transgenic barley lines produced by particle bombardment and Agrobacterium-mediated techniques.

Two barley transformation systems, Agrobacterium-mediated and particle bombardment, were compared in terms of transformation efficiency, transgene copy number, expression, inheritance and physical structure of the transgenic loci using fluorescence in situ hybridisation (FISH). The efficiency of Agrobacterium-mediated transformation was double that obtained with particle bombardment. While 100% of the Agrobacterium-derived lines integrated between one and three copies of the transgene, 60% of the transgenic lines derived by particle bombardment integrated more than eight copies of the transgene. In most of the Agrobacterium-derived lines, the integrated T-DNA was stable and inherited as a simple Mendelian trait. Transgene silencing was frequently observed in the T1 populations of the bombardment-derived lines. The FISH technique was able to reveal additional details of the transgene integration site. For the efficient production of transgenic barley plants, with stable transgene expression and reduced silencing, the Agrobacterium-mediated method appears to offer significant advantages over particle bombardment.

Agriculture↗
PubMed1998

Substance use disorders. Difficulties in diagnoses.

Patients attempt, consciously or unconsciously, to minimize or disguise their substance use, in part to preserve shreds of self-respect, avoid guilt and shame, and avoid the real or imagined criticism of others. It is ironic that substance users not only use the substance to gain access to pleasant events or escape or avoid unpleasant events, but also to deny, minimize, or disguise that very use for the same reasons.

Adolescent↗
PubMed1998

Biological variation of cardiac markers: analytical and clinical considerations.

The analytical, within-subject and between-subject components of variation were estimated for serum total creatine kinase (TCK) activity, CK-MB (creatine kinase-MB) activity, CK-MB mass, ratios of CK-MB activity and CK-MB mass to TCK activity and myoglobin concentration in a cohort of 16 apparently healthy subjects over 5 days. Analytical goals based on biological variation showed that, for all quantities except CK-MB mass, methodological improvement is warranted. All cardiac markers showed marked individuality which casts doubt on the utility of conventional population-based reference values as interpretative criteria. The critical differences required for significance of changes in serial results differ markedly from marker to marker and the data allow generation of objective criteria for monitoring individuals.

Adult↗
PubMed1996

Risk of physical abuse to children of spouse abusing parents.

The purpose of this study is to estimate the gender-specific probability of a violent spouse also physically abusing his or her child within a representative sample. The study is based on a sample of 3,363 American parents interviewed for the 1985 National Family Violence Survey. The study shows that marital violence is a statistically significant predictor of physical child abuse. The greater the amount of violence against a spouse, the greater the probability of physical child abuse by the physically aggressive spouse. This relationship is stronger for husbands than for wives. The probability of child abuse by a violent husband increases from 5% with one act of marital violence to near certainty with 50 or more acts of marital violence. The predicted probability of child abuse by a violent wife increases from 5% with one act of marital violence to 30% with 50 or more acts of marital violence. Implications for divorce custody proceedings are discussed.

Adolescent↗
PubMed1995

The neurotoxin, beta-N-methylamino-L-alanine (BMAA) interacts with the strychnine-insensitive glycine modulatory site of the N-methyl-D-aspartate receptor.

Electrophysiological and receptor binding techniques were used to determine whether the neurotoxin beta-N-methylamino-L-alanine (BMAA), a monocarboxylic amino acid, can act at the strychnine-insensitive glycine modulatory site to modify the activity of N-methyl-D-aspartate receptors. DL-BMAA but not L-BMAA reversibly potentiated the amplitude of NMDA-activated currents. Neither DL-BMAA nor L-BMAA were able independently to active currents. The reversal potential and the potential-dependence of the amplitude were not affected by DL-BMAA. The DL-BMAA effect was reversibly antagonized by 7-chlorokynurenic acid. Concentration jump experiments showed that the time course of the "off" response of NMDA-activated currents in the presence of DL-BMAA is faster than in the presence of glycine, suggesting that DL-BMAA dissociates from the receptor more rapidly than glycine. DL-BMAA produced a concentration-dependent displacement of [3H]glycine binding which was additive with that of 7-chlorokynurenic acid. These data indicate that D-BMAA could act as a stereospecific modulator of NMDA receptor function by acting as an agonist at the strychnine-insensitive glycine modulatory site of the NMDA receptor.

Amino Acids, Diamino↗
PubMed1995

Professional pilots' views of alcohol use in aviation and the effectiveness of employee-assistance programs.

Pilots holding the Airline Transport Pilot certificate were surveyed about the seriousness of the alcohol problem in various areas of aviation and about the importance of a number of possible reasons why a pilot might drink and fly. They also rated a number of actions in terms of their potential effectiveness for reducing inappropriate alcohol use, and they evaluated a number of characteristics of employee-assistance programs. Respondents judged employee-assistance programs to be the best way to reduce problem drinking. They also identified areas in which currently available employee-assistance programs could be improved.

Accidents, Aviation↗
PubMed1994

Expression of functional metabotropic and ionotropic glutamate receptors in baculovirus-infected insect cells.

An ionotropic glutamate receptor of the kainate subtype (GluR6) and a G-protein coupled metabotropic glutamate receptor (mGluR1 alpha) were expressed and studied in two insect cell lines: sf9 cells from Spodoptera frugiperda and MG1 cells from Trichoplusia ni. Application of kainate to GluR6-infected MG1 cells produced kainate-activated currents. Glutamate activation of mGluR1 alpha in MG1- and sf9-infected cells caused rapid, transient increases in intracellular calcium levels. This effect was more pronounced in MG1 cells compared to sf9 cells. These results indicate that functional glutamate receptors can be expressed in the baculovirus system, and that MG1 cells may have several advantages over the widely used sf9 cells for studying the functional properties of receptors and channels.

Animals↗
PubMed1993

Effects of a muscarinic antagonist on various components of female sexual behavior in the rat.

The effects of the muscarinic antagonist scopolamine on lordosis, solicitation, pacing, approach, attractivity, and activity were evaluated in ovariectomized rats brought into sexual receptivity with estrogen and progesterone. Systemic (1 mg/rat) or intraventricular (10 micrograms bilaterally) administration of scopolamine significantly reduced the incidence of lordosis and solicitation behaviors and disrupted typical pacing of sexual contacts with a stimulus male. In addition, females avoided contact with a stimulus male, but not a stimulus female, following intraventricular infusion of scopolamine. The levels of general activity and frequencies of sexual contacts were similar in females treated intraventricularly with scopolamine and vehicle solutions. Consequently, scopolamine disrupted various components of sexual behavior, including lordosis, solicitation, pacing, and approach, without altering female attractivity or general activity.

Animals↗
PubMed1992

The effect of estrogen treatment on scopolamine inhibition of lordosis.

Previous evidence indicates that the cholinergic muscarinic antagonist, scopolamine, inhibits lordosis in female rats. In the experiments reported here, the effects of various doses and repeated administrations of estrogen on the scopolamine inhibition of lordosis were examined. In the first experiment, intraperitoneal injections of scopolamine (1 mg/rat) completely inhibited lordosis in ovariectomized rats primed with low doses of estradiol benzoate (0.25 or 0.5 micrograms for 3 days) and progesterone (500 micrograms). However, scopolamine was significantly less effective in inhibiting lordosis in females primed with a higher dose of estradiol benzoate (25 micrograms for 3 days) and progesterone (500 micrograms). When hormone priming was repeated on subsequent weeks, scopolamine continued to inhibit lordosis in females that received 0.25 micrograms estradiol benzoate but was less effective in females primed with 0.5 micrograms. Scopolamine failed to inhibit lordosis in females treated with 25 micrograms estradiol benzoate on these later tests. In the second experiment, various doses of scopolamine (1, 2, or 4 mg/rat) were administered intraperitoneally to females primed with the highest dose of estradiol benzoate (25 micrograms) and progesterone (500 micrograms). Lordosis was inhibited equally by all scopolamine doses during the first week. As in the first experiment, scopolamine failed to inhibit lordosis at all doses on subsequent weeks of testing. These results indicate that the ability of scopolamine to inhibit lordosis is reduced by increasing the dose or the number of estrogen exposures. Because higher doses of scopolamine failed to restore its inhibitory effect on lordosis an upregulation of muscarinic receptors by estrogen cannot account for the reduced effectiveness of scopolamine.

Animals↗
PubMed1992

Professional pilots' evaluation of the extent, causes, and reduction of alcohol use in aviation.

Pilots holding the ATP rating were surveyed to obtain judgments concerning the seriousness of the alcohol problem in various areas of aviation, the reasons for alcohol use, and the probable effectiveness of strategies intended to reduce alcohol use in aviation. Alcohol use was judged to be a more serious problem in general aviation than in corporate, charter, regional, and major airline activities. Respondents identified the individual's inability to control alcohol use as a primary reason for drinking and flying, and they endorsed remedies that are directed toward those individuals who are seen as the source of the problem. Other factors considered important causes of drinking and flying included pilots' beliefs that they can compensate for alcohol's effects and their lack of knowledge about the rate of decrease in blood alcohol concentration (BAC) that occurs as a function of time and amount consumed.

Aerospace Medicine↗
PubMed1992

Synovial fluid stimulates the proliferation of rabbit ligament. Fibroblasts in vitro.

This study was designed to test the hypothesis that synovial fluid may be inhibitory to cell proliferation. The effects of bovine synovial fluid (SF) and hyaluronic acid (HA) on the proliferation of normal rabbit medial collateral ligament (MCL), anterior cruciate ligament (ACL), and MCL scar cells were therefore investigated. Cell lines established from rabbit tissues were plated, incubated, and allowed to attach before treatment with varying concentrations of SF, HA, and a balanced salt solution (BSS). The BSS group was added as a control to observe the effects of media dilution alone on cell proliferation. Cell numbers from each group were quantified at 24, 48, 72, and 96 hours. Results showed that for all cell types, cell proliferation during the log phase of growth was significantly stimulated by SF. Maximum stimulation occurred in 20% SF with stimulation decreasing at higher concentrations of SF. HA had virtually no effect on scar and ACL cells, and only a slight stimulatory effect on MCL cells. Media dilution had no effect on scar cells and began to inhibit cell proliferation of ACL and MCL cells only at high dilutions. These findings suggest that low concentrations of bovine SF stimulate proliferation of rabbit ligament and scar fibroblasts in vitro by a mechanism that appears not to involve HA. Even in high concentrations, SF was not inhibitory to proliferation. The implications of these findings to ligament healing and normal ligament physiology require further investigation.

Animals↗
PubMed1991

Effect of floor conditions upon frictional characteristics of squash court shoes.

Vertical (FN) and horizontal (FH) forces were recorded while four vertically-loaded court shoes were dragged horizontally across six types of floor surface. Variation in coefficient of limiting friction (FH/FN) between floor surfaces was greater than that between shoes. Squash strokes were also performed on the same surfaces during which FH/FN was calculated. Slips occurred on some surfaces either at heel contact or upon attainment of full-sole contact. It is concluded that the coefficient of limiting friction obtained during full-sole contact with the floor is a suitable means of distinguishing between tractional qualities of shoes. Alternatively, this measure is an inadequate predictor of the likelihood of slips in the game of squash racquets. Dusty floor conditions produce poor traction as does a damp sealed floor. As sweat droplets are unavoidable in the game, floors sealed with urethane represent a significant hazard. Bare, clean, wooden flooring which can absorb moisture represents a better surface than a sealed floor from the point of view of traction.

Biophysical Phenomena↗
PubMed1990

Combined DC and ELF magnetic fields can alter cell proliferation.

Effects of extremely-low-frequency (ELF) electromagnetic fields on proliferation of rabbit-ligament fibroblasts were examined. Markedly different effects, ranging from inhibition to stimulation of proliferation, were obtained, depending on the signal parameters of amplitude, frequency, and DC magnetic field. These results demonstrate that simple, single-frequency signals can have dramatic effects on ligament cells, which may be useful for bioelectrical stimulation of growth and repair. Also, the range of frequencies examined in this study covered those commonly used in transmission of electrical energy (50 or 60 Hz), which indicates that further study of possible effects of exposure to fields generated by power transmission equipment is warranted.

Animals↗
PubMed1990

Establishment and comparison of fibroblast cell lines from the medial collateral and anterior cruciate ligaments of the rabbit.

We have developed a procedure to explant fibroblasts from the anterior cruciate ligament (ACL) and the medical collateral ligament (MCL) of the rabbit knee, and have optimized conditions for maintaining them in culture. Maximal growth for both ACL and MCL cells was obtained with Dulbecco's modified Eagle's medium supplemented with 15% fetal bovine serum and 250 microM ascorbate. ACL and MCL fibroblasts displayed intrinsic differences in their responses to changes in culture parameters. Specifically, they displayed different growth responses when plated at different densities and responded to RPMI 1640 medium in very different ways. There were also biochemical differences between the cell types. Both cell types produced similar amounts of collagen in culture, but the ratio of type I to type III, the major collagen subtypes produced by these cells, were different. ACL fibroblasts produced 86.7% type I and 13.3% type III, and MCL fibroblasts produced 71.1% type I and 28.9% type III. In addition, total protein produced by ACL fibroblasts was higher than that produced by MCL cells. This confirms the suggestions of previous researchers that such differences might exist.

Animals↗
PubMed1990

Pilots' knowledge of blood alcohol levels and the 0.04% blood alcohol concentration rule.

A national sample of licensed pilots was surveyed regarding their knowledge of the Federal Aviation Administration's (FAA) 0.04% blood alcohol concentration (BAC) limit, the relationship between the number of drinks and BAC, and the manner in which BAC decays with time. A majority of the 1039 respondents were unaware of the 1985 0.04% BAC rule change. In addition, many lacked an understanding of the relationship between the amount of alcohol consumed and the resulting BAC, and of the rate at which BAC decays. The number of drinks necessary to raise BAC to specific levels was frequently overestimated, and the amount of time necessary for BAC to decay was frequently underestimated. These errors were more pronounced for moderate and heavy drinkers than for abstainers and infrequent drinkers. These results suggest that pilots could have difficulty if they attempt to use the 0.04% BAC value as a guide to safety in their flying activities.

Accidents, Aviation↗
PubMed1989

Studies on the alignment of fibroblasts in uniform applied electrical fields.

Uniform electrical fields have been applied to human gingival fibroblasts by means of uniform ionic currents passed through a thin chamber. Cells were observed to align in fields between 0.1 and 1.5 V/mm but did not display directed motion toward the anode or the cathode of the chamber. Statistical analysis of directional data was used to distinguish threshold levels of orientation at low field intensities, to quantify the dependence of alignment on time and field intensity, and to analyze differences between alignment of cells treated with the Ca2+ transport modifiers A23187, verapamil, and lanthanum. Alignment occurred at a steady rate and was dependent in a saturating fashion on field strength. The Ca2+ ionophore A23187 had a significant inhibitory effect on cell alignment in applied electrical fields; however, the Ca2+ channel blockers lanthanum and verapamil did not have a significant effect on alignment.

Biological Transport↗