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Biomedical subjects

S M Ross

Publications and source records attributed to S M Ross.

At least 37 records · Page 2Linked to original sources
PubMed1989

Self-efficacy in alcoholics: clinical validation of the Situational Confidence Questionnaire.

Recent theory and empirical data suggest that self efficacy plays an important role in resistance to relapse for substance abusers. This study investigated the validity of the Situational Confidence Questionnaire (SCQ), a new instrument designed to measure self-efficacy expectations in purported high-risk drinking situations. The SCQ was administered to 46 short-term sober (STS) and 25 long-term sober (LTS) alcoholics. STS subjects were newly admitted alcohol treatment patients and LTS subjects had been abstinent for at least one year. Results indicated significantly higher self efficacy for LTS subjects than for STS subjects on total score and on 7 of the 8 subscales (p less than .001). Stepwise discriminant analysis yielded a linear combination of three subscales to account for 49% of the total variance; 92% of the LTS and 65% of the STS subjects were correctly identified by the classification function. These results extended earlier work with the SCQ using newly sober subjects and, in addition, provide encouraging validity data for the SCQ.

Alcoholism↗
PubMed1989

Beta-N-oxalylamino-L-alanine action on glutamate receptors.

beta-N-Oxalylamino-L-alanine (L-BOAA) is a non-protein excitatory amino acid present in the seed of Lathyrus sativus L. This excitotoxin has been characterized as the causative agent of human neurolathyrism, an upper motor neuron disease producing corticospinal dysfunction from excessive consumption of the lathyrus pea. Previous behavioral, tissue-culture, and in vitro receptor binding investigations revealed that L-BOAA might mediate acute neurotoxicity through quisqualate (QA)-preferring glutamate receptors. The present study demonstrates the stereospecific action of L-BOAA on glutamate receptor binding in whole mouse brain synaptic membranes. L-BOAA was most active in displacing thiocyanate (KSCN)-sensitive specific tritiated (RS)-alpha-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) binding (i.e., QA receptor) (Ki = 0.76 microM) with a rank-order potency of QA greater than kainate greater than N-methyl-D-aspartate (NMDA). By contrast, the nonneurotoxic D-BOAA isomer (100 microM) was essentially inactive in displacing radioligands for glutamate receptors, except the NMDA site, where it was equipotent with L-BOAA. Scatchard analysis of L-BOAA displacement of specific [3H]AMPA binding indicated competitive antagonism (KD: control, 135 nM; L-BOAA, 265 nM) without a significant change in QA-receptor density, and Hill plots yielded coefficients approaching unity. Differential L-BOAA concentration-dependent decreases in specific [3H]AMPA binding were observed in synaptic membranes, indicating that the neurotoxin was more potent in displacing specific binding from frontal cortex membranes, followed by that for corpus striatum, hippocampus, cerebellum, and spinal cord. (ABSTRACT TRUNCATED AT 250 WORDS)

Alanine↗
PubMed1989

Students' time on learning tasks in special education.

The purpose of this study was to measure, through naturalistic observation procedures, the use of time among handicapped students in four special education alternatives--regular class, resource room, special class, and special school. The sample included 230 elementary age students enrolled in 58 classes in 16 schools. ANOVA comparisons revealed that the least restrictive alternatives, particularly the resource room, made more in-class learning time available. Discussion includes recommendations for increasing learning time.

Child↗
PubMed1988

Pilots' attitudes toward alcohol use and flying.

Questionnaires were sent to a national sample of licensed pilots. Respondents reported their flying experience and their drinking behavior. They also indicated the number of drinks that they believed could be safely consumed 3 hours (h) before flying or driving, and estimated the numbers of hours a person should wait, after drinking, before attempting to fly or drive. Similar questions were included regarding marijuana use. Respondents were much more conservative in their attitudes toward the use of alcohol prior to flying than prior to driving. This relationship held both for the number of drinks judged safe 3 h prior to flying or driving and for estimates of the waiting interval that would be appropriate following alcohol consumption. In addition, attitudes toward alcohol use were related to respondents' own drinking behavior, with moderate and heavy drinkers more tolerant of alcohol use in flying and driving situations than abstainers.

Adult↗
PubMed1987

Specific antagonism of excitotoxic action of 'uncommon' amino acids assayed in organotypic mouse cortical cultures.

Beta-N-Methylamino-L-alanine (BMAA) and beta-N-oxalylamino-L-alanine (BOAA) are chemically related excitant amino acids present in the seeds of Cycas circinalis and Lathyrus sativus, respectively. Consumption of these seeds has been linked to Guam amyotrophic lateral sclerosis (BMAA) and lathyrism (BOAA) (a form of primary lateral sclerosis). We report that the acute neuronotoxic actions of these amino acids are blocked selectively by specific glutamate receptor antagonists. Administration of BOAA and BMAA to neonatal mouse cortex explants (EC100 = 28 microM and 1.6 mM, respectively) rapidly induces postsynaptic vacuolation (PSV) and neuronal degeneration characterized by dark/shrunken (D/S) cells. BOAA-mediated neuronotoxic effects are attenuated in a concentration-dependent manner by cis-2,3-piperidine dicarboxylic acid (PDA), an antagonist of quisqualate (QA)-preferring and kainate (KA)-preferring glutamate receptors. PDA maximally protected against BOAA-induced PSV by 84% at 1 mM and D/S cells by 80% at 0.5 mM. BMAA-induced cellular changes were antagonized selectively in a concentration-dependent manner by 2-amino-7-phosphono-heptanoic acid (AP7), an N-methyl-D-aspartate (NMDA) glutamate-receptor antagonist. AP7 maximally protected against BMAA-induced PSV and D/S by 88% at 1.0 and 0.5 mM, respectively. These protective actions were selective and specific since AP7 failed to attenuate BOAA-induced alterations, and PDA was ineffective in ameliorating BMAA-induced changes. Other glutamate receptor antagonists (glutamic diethyl ester and streptomycin) failed to protect the explants from the destructive action of either toxin. Taken collectively, our data indicate that the acute neuronotoxic actions of BOAA and BMAA (or a metabolite) operate through different glutamate receptor species.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Amino-5-phosphonovalerate↗
PubMed1987

Breast-feeding support.

With the objective of prolonging unsupplemented breast-feeding, three groups of breast-feeding mothers were provided with support by frequent home visits by different types of health workers (including a lay worker). A fourth group received limited support and a fifth group received no support. Significant differences were found between some of the groups, the lay worker having the greatest impact. The results indicate that a home visitation programme could be successful in promoting breast-feeding.

Adult↗
PubMed1987

Guam amyotrophic lateral sclerosis-parkinsonism-dementia linked to a plant excitant neurotoxin.

The decline in the high incidence of amyotrophic lateral sclerosis, parkinsonism, and Alzheimer-type dementia among the Chamorro population of the western Pacific islands of Guam and Rota, coupled with the absence of demonstrable viral and hereditable factors in this disease, suggests the gradual disappearance of an environmental factor selectively associated with this culture. One candidate is seed of the neurotoxic plant Cycas circinalis L., a traditional source of food and medicine which has been used less with the Americanization of the Chamorro people after World War II. Macaques were fed the Cycas amino acid beta-N-methylamino-L-alanine, a low-potency convulsant that has excitotoxic activity in mouse brain, which is attenuated by N-methyl-D-aspartate receptor antagonists. These animals developed corticomoto-neuronal dysfunction, parkinsonian features, and behavioral anomalies, with chromatolytic and degenerative changes of motor neurons in cerebral cortex and spinal cord. In concert with existing epidemiological and animal data, these findings support the hypothesis that cycad exposure plays an important role in the etiology of the Guam disease.

Amino Acids, Diamino↗
PubMed1987

Discovery and partial characterization of primate motor-system toxins.

beta-N-Oxalylamino-L-alanine (BOAA) and beta-N-methylamino-L-alanine (BMAA) are chemically related excitant amino acids isolated from the seed of Lathyrus sativus (BOAA) and Cycas circinalis (BMAA), consumption of which has been linked to lathyrism (an upper motor neuron disorder) and Guam amyotrophic lateral sclerosis (ALS), respectively. Both diseases are associated with degeneration of motor neurons. Experimentally, single doses of BOAA or BMAA induce seizures in neonatal mice and postsynaptic neuronal oedema and degeneration in explants of mouse spinal cord and frontal cortex. Preliminary studies show that these behavioural and pathological effects are differentially blocked by glutamate-receptor antagonists. In macaques, several weeks of daily oral doses of BOAA produce clinical and electrophysiological signs of corticospinal dysfunction identical to those seen in comparably well-nourished animals receiving a fortified diet based on seed of Lathyrus sativus. By contrast, comparable oral dosing with BMAA precipitates tremor and weakness, bradykinesia and behavioural changes, with conduction deficits in the principal motor pathway. BOAA and BMAA (or a metabolite thereof) are the first members of the excitotoxin family to have been shown to possess chronic motor-system toxic potential. These observations provide a rational basis for searching for comparable endogenous neurotoxins in sporadic and inherited forms of human motor neuron disease.

Alanine↗
PubMed1987

Specific antagonism of behavioral action of "uncommon" amino acids linked to motor-system diseases.

Beta-N-methylamino-L-alanine (BMAA) and beta-N-oxalylamino-L-alanine (BOAA) are chemically related amino acids present in the seeds of Cycas circinalis and Lathyrus sativus, respectively. Consumption of these seeds has been linked to Guam amyotrophic lateral sclerosis (BMAA) and lathyrism (BOAA; a form of primary lateral sclerosis). A single large dose of BOAA or BMAA causes seizures in newborn mice and postsynaptic neuronal edema and degeneration in CNS explants. We report that the acute neurotoxic actions of these amino acids are blocked selectively by specific glutamate-receptor antagonists (administered intracerebroventricularly) (i.c.v.) prior to the amino acid. Administration of BOAA i.c.v. to neonatal mice (ED100 = 50 micrograms) elicits a spectrum of time-dependent behavioral states including arm and leg rigidity, convulsions, and resting tremor. These are blocked in a dose-dependent manner by cis-2,3-piperidine dicarboxylic acid (PDA), an antagonist of quisqualate (QA)-preferring (A2) and kainate (KA)-preferring (A3) glutamate receptors (ED50s; 2.8 micrograms, rigidity; 1.4 micrograms, convulsions; 2.4 micrograms, resting tremor). BMAA induces a transitory hyperexcitable state followed by a long-lasting whole-body shake/wobble (ED100 = 1,000 micrograms, i.c.v.). These responses are antagonized selectively and dose-dependently by 2-amino-7-phosphonoheptanoic acid (AP7), an N-methyl-D-aspartate (NMDA) or A1 glutamate-receptor antagonist (ED50 = 0.45 microgram). Taken collectively, our data indicate that the acute neuronotoxic actions of BOAA and BMAA (or a metabolite) operate through different glutamate-receptor species. BMAA likely exerts most of its action indirectly via the A1 glutamate receptor, while BOAA acts principally at the A2 and/or A3 receptor.

2-Amino-5-phosphonovalerate↗
PubMed1987

Children's and adults' predictive saccades to square-wave targets.

Predictive saccades to square-wave targets were investigated in school age children and adults at target frequencies of 0.25, 0.5, 0.75, 1.0 and 1.25 Hz. Both children and adults showed predictive tracking that was greatest at the middle of the frequency range, but children's saccade latencies were greater than those of adults at frequencies of 0.5 Hz and above. The variability of saccade latencies for children and adults were comparable. These results were interpreted as indicating that both children's and adults' oculomotor systems include a prediction operator and respond to predictable stimuli in qualitatively similar, although quantitatively different, ways.

Adult↗
PubMed1987

Automation of protein assays with a microcomputer interfaced to a spectrophotometer.

We have developed a system for semi-automatic protein quantitation assays based on an inexpensive, general-purpose microcomputer. A commercial curve fitting program was modified for direct data input from the spectrophotometer via an analog to digital converter. The software provides specific prompts for protein assays resulting in a rapid and user friendly, semi-automated system. A listing of the protein assay results are printed, or stored to a magnetic disk, along with a graphic representation of the standard curve.

Autoanalysis↗
PubMed1987

Collection and analysis of complex ELISA data using a microcomputer.

A system for automatic Enzyme-Linked Immunosorbent Assay (ELISA) data collection and processing is described. Hardware for the system consists of a Dynatech microplate reader and Apple II series microcomputer. Software developed by the authors allows automatic configuration of the reader and direct data input from the microplate reader to the microcomputer. After optical density data is input through the interface, it can be printed out as either optical density values, or as scaled values (from 0 to 9) in a color-coded matrix. Data can be stored and later recalled in either format, allowing several sets of data to be merged into one large, color-coded chart. Results from several different microplates can be combined and sorted in a single printout to expedite interpretation of data.

Computers↗
PubMed1986

Osteoclasts and osteoblasts migrate in opposite directions in response to a constant electrical field.

We have investigated in vitro the effects of the electrical field produced by constant current on freshly isolated rabbit osteoclasts and on well characterized clonal rat osteoblastlike cells. At field strengths of 0.1 and 1 V/mm, the osteoclasts migrated rapidly toward the positive electrode, whereas the osteoblastlike cells migrated in the opposite direction, toward the negative electrode. Thus, different cell types from the same tissue can respond differently to the same electrical signal. These results have important implications for hypotheses concerning the cellular mechanism of galvanotaxis, and may also clarify the cellular basis of the clinical application of electrical stimulation of bone healing.

Animals↗
PubMed1986

ODDC and MULTIGRAPH: programs for spectrophotometer data collection and manipulation using a microcomputer.

A software package is described that collects, graphs, performs peak sensing, and prints data from a spectrophotometer interfaced to an Apple II microcomputer with an ADALAB analog-to-digital converter card. Data collection and storage is performed by an interpreted BASIC program with machine language subroutines. Recalling, graphing, and printout of the data is accomplished by a separate compiled BASIC program. Both of these programs, as well as assisting utility programs, are under control of a menu program. The programs take advantage of all available memory in the 64-K Apple II computer to allow for storage of up to 12 600 data points (7 hours of data collection at a sampling rate of 1 sample every 2 s). As the data collection program provides peak sensing, and the capability of annotating various time points, the programs are ideally suited for use in column chromatography.

Chromatography↗
PubMed1985

Action of acrylamide on selected enzymes of energy metabolism in denervated cat peripheral nerves.

The effect of acrylamide on selected glycolytic and citric acid cycle enzymes has been studied in denervated cat sciatic nerves in vitro and in vivo. The enzyme activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), neuron specific enolase (NSE), succinate dehydrogenase (SDH), and lactate dehydrogenase (LDH), has been examined in saline-perfused, desheathed and denervated peroneal (P) and tibial (T) nerves from cats treated with acrylamide (15 mg/kg/day, s.c.) or vehicle for 15 days. GAPDH activity in denervated P and T nerve stumps was 2.0- and 2.3-fold higher than normal P and T nerve values. GAPDH activity in Schwann cells in denervated P and T nerves of acrylamide-treated cats was markedly reduced (56% and 61% of untreated denervated nerves, respectively). LDH and SDH activities were unaffected by acrylamide and NSE activity was absent in denervated nerve stumps. Acrylamide (0.5 and 20 mM) inhibited GAPDH activity in denervated nerve homogenates by 67% and 29%, respectively. This study demonstrates that acrylamide inhibits GAPDH in Schwann cells. The significance of GAPDH inhibition by acrylamide in denervated nerves and its relation to distal axonopathy has been discussed.

Acrylamide↗
PubMed1985

Syphilis in pregnant black women.

Serological tests for syphilis (with rapid plasma reagin) were performed in 2 767 women attending the antenatal clinic of King Edward VIII Hospital, Durban, for their first, booking visit. The test was repeated at the 36th week of pregnancy. A total of 152 women (5,5%) were assumed to have syphilis. In addition, 4 (11,8%) of 34 patients who were seronegative at less than 32 weeks of pregnancy had a positive serological test result at 36 weeks.

Black or African American↗