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Biomedical subjects

S A Ferguson

Publications and source records attributed to S A Ferguson.

At least 55 records · Page 3Linked to original sources

Observational learning and the use of retrieval information during the second and third years.

The authors report 2 cross-sectional studies dealing with observationally derived acquisition of serial and sequentially coordinated activities in children between 12 and 30 months. In Study 1, greater improvements in activity occurred at every age beyond 12 months for modeling than for control groups, demonstrating age-related advances in ability to use modeling in connection with these action classes. However, significant gains did not imply complete reconstruction from memory, which resulted most typically for fewer than 50% of children. Moreover, when sequential tasks were subdivided on the basis of task demands, somewhat greater observationally derived change was found for the class of constrained tasks than for free-standing tasks. Study 2 concentrated on serial task performance and the use of massive retrieval cues in the form of assembled stationary displays, to test the efficacy of such cues in helping children reproduce the serial activities they had observed. Again, children who witnessed modeling were better at reproducing serial assemblies than control-group children. The use of retrieval information, however, was noticeably lacking as late as 22 months, whereas substantial gains were made over the next 6 months. The outcome was supported by exploratory processing results for the 2 ages. Increased use of the cues by 28 months appears to reflect important developments in awareness of the uses to be made of retrieval information, as well as success in its utilization.

Attention↗

Seating positions and children's risk of dying in motor vehicle crashes.

OBJECTIVES: To determine the effects of seating position, combined with restraint use and airbag status, on children's risk of dying in crashes. METHODS: Using 1988-95 data from the United States Fatality Analysis Reporting System, risk of death was compared among front and rear seated passengers aged 12 and younger who were involved in fatal crashes for different categories of restraint use and in vehicles with and without passenger airbags. RESULTS: Restrained children in rear seats had the lowest risk of dying in fatal crashes. Among children seated in the rear, risk of death was reduced 35% in vehicles without any airbags, 31% in vehicles equipped only with driver airbags, and 46% in vehicles with passenger airbags. Both restrained and unrestrained children aged 0-12 were at lower risk of dying in rear seats. Rear seats also afforded additional protection to children aged 5-12 restrained only with lap belts compared with lap/shoulder belted children in front seats. Children were about 10-20% less likely to die in rear center than in rear outboard positions. CONCLUSIONS: Parents and others who transport children should be strongly encouraged to place infants and children in rear seats whether or not vehicles have airbags. Existing laws requiring restraint use by children should be strengthened and actively enforced.

Accidents, Traffic↗

Effectiveness and role of driver education and training in a graduated licensing system.

Formal driver education/training programs exist in almost all jurisdictions around the world. They are generally accepted as an efficient and effective means for learning to drive, and, more importantly, for learning to drive safely, although empirical evidence for safety benefits is lacking. Recently, there has been a heightened interest in driver education/training, largely as a result of the adoption of graduated licensing in a few jurisdictions in North America and elsewhere. These jurisdictions have effectively elevated the status of driver education/training by integrating it into the licensing system. Implicitly, this suggests that driver education provides safety benefits. This article provides a contemporary review of the value of driver education/training, particularly in relation to new licensing systems such as graduated ones. The article examines the safety benefits of driver education/training and considers the merits of integrating driver education/training programs with new approaches to the licensing of young drivers.

Accidents, Traffic↗

Reductions in deaths in frontal crashes among right front passengers in vehicles equipped with passenger air bags.

CONTEXT: Virtually all new cars now are equipped with passenger air bags. Determining whether passenger air bags are saving lives is important, particularly because passenger air bags have caused some deaths among children and adults. OBJECTIVE: To assess the effectiveness of passenger air bags in reducing the risk of death in frontal crashes for right front passengers. DESIGN: Air bags are designed to protect occupants in frontal crashes. Using Fatality Analysis Reporting System data for calendar years 1992 through 1995, the relative frequency of right front passenger deaths in frontal vs nonfrontal fatal crashes was compared for cars with dual air bags and for cars with driver-only air bags. MAIN OUTCOME MEASURES: Odds of right front passengers dying in frontal compared with nonfrontal fatal crashes were computed for 1992 through 1995 model year cars with dual air bags and for cars with driver-only air bags. Percentage reductions in right front passenger deaths in dual air bag vehicles were estimated. RESULTS: Right front passenger fatalities were 18% lower than expected in frontal crashes of cars with dual air bags and 11% lower in all crashes. An estimated 73 fewer than expected right front passengers died in 1992 through 1995 model cars with dual air bags during 1992 through 1995. The risk of frontal crash death for right front passengers in cars with dual air bags was reduced 14% among those reported to be using belts and 23% among belt nonusers. Children younger than 10 years in cars with dual air bags had a 34% increased risk of dying in frontal crashes. CONCLUSIONS: Passenger air bags were associated with substantial reductions in fatalities among right front passengers in frontal crashes. However, more children are being killed than are being saved by air bags. Immediate countermeasures to reduce the dangers of air bags to children and adults are suggested.

Accidents, Traffic↗

Quipazine and light have similar effects on c-fos induction in the rat suprachiasmatic nucleus.

The effects of the serotonin agonist, quipazine, on the induction of c-fos in the suprachiasmatic nucleus of the rat was examined at different times of the 24 h cycle. Quipazine administered at night induced Fos production in a dose dependent manner (1, 3, 10, 30 mumol/kg) in the ventrolateral portion of the suprachiasmatic nucleus at ZT18. Administration of the highest dose at other times resulted in c-fos induction at ZT15 but not at other times of the day or subjective day examined (CT6 and ZT12). When compared to the effects of light pulses (2 lux/1 min), quipazine only caused c-fos induction at times when light caused induction. Our results support a role of serotonergic pathways in the transmission or modulation of photic information from the retina to the suprachiasmatic nucleus of the rat.

Animals↗

A literature review of low back disorder surveillance measures and risk factors.

OBJECTIVE: The goal of this literature review was to gain insight into low back disorder risk factors via a critical examination of the surveillance measures and analysis techniques employed in existing literature. DESIGN: Fifty-seven original articles were evaluated and categorized as a function of their surveillance measures. BACKGROUND: There have been a plethora of articles concerning the causes of low back disorder, yet no specific risk factors are consistently associated with the development of these disorders. It was hypothesized that different low back surveillance measures and variations in risk factor (dependent variable) measurements have led to the inconsistencies in the literature. METHODS: Five low back disorder surveillance measures and five risk factor categories were defined for this review. Each article was classified on several criteria including: surveillance measures, risk factors, statistical methods, population and type of study. Summary statistics were calculated for the percentage of positive findings as a function of surveillance measure and risk factor category. RESULTS: The most consistently defined surveillance measure was incidence of low back disorder, with 82% of those investigating it as claims from medical records or Occupational Safety and Health Administration records. The combination of surveillance measures and risk factor influenced the outcome of investigations. Ninety-one percent of the direct or video methods of measuring exposure risk factor influenced outcome. Psychosocial measures had positive findings in 70% of the studies examining lost time. Finally, statistical methodology was critical in the outcome of these investigations. CONCLUSIONS: The surveillance measure of incidence had more positive findings, with exposure risk factors and the surveillance measures indicating more advanced stages of low back disorder such as lost time had more positive findings with psychosocial risk factors. Thus, as low back disorders progress to disability, the psychosocial risk factors play a more prominent role. RELEVANCE: In order to prevent low back disorders we must first understand the plethora of epidemiological literature. This literature review provides new insight on the critical issues that have contributed to the results of previous research.

Journal Article↗

Methylazoxymethanol-induced micrencephaly in the brown Norway strain: behavior and brain weight.

A single injection of 20 mg/kg methylazoxymethanol acetate (MAM) on gestational day 14 in Brown Norway rats produced micrencephalic offspring (whole brain approximately equal to 65% of control). Despite the micrencephaly, MAM-induced alterations in behavior assessed here were relatively mild. The MAM-treated rats exhibited increased activity under darkened conditions in a complex maze and marginally increased activity after a challenge of methamphetamine. Open field activity, running wheel activity, and emergence behavior using a light/dark apparatus were not significantly affected. Compared with a similar study of Sprague-Dawley micrencephalics [Ferguson S.A., Racey F.D., Paule M.G. and Holson R.R. (1993) Behavioral effects of methyloxymethanol-induced microencephaly. Behav. Neurosci. 107, 1-101], frontal cortex and striatum weights were more reduced in Brown Norway micrencephalics. The MAM-induced behavioral alterations in the Brown Norway strain may have appeared attenuated compared to alterations shown by MAM-treated Sprague-Dawley rats due to differences in baseline between these two strains. Compared to control Sprague-Dawley rats in the previous study, control Brown Norway rats were more active in the open field and running wheels, but less active in the complex maze, exhibiting little to no learning. Emergence tests indicated increased dark preference in Brown Norway rats. Baseline behavior (increased activity and light shyness) of control Brown Norway rats was similar to that of MAM-treated Sprague-Dawley rats; a potential confound in the detection of behavioral effects of a compound. These findings emphasize the effects that strain selection may have on the outcome and interpretation of toxicological/teratological studies.

Animals↗

Drinking drivers missed at sobriety checkpoints.

OBJECTIVE: Sobriety checkpoints are an effective deterrent to alcohol-impaired driving although a substantial proportion of drinking drivers who pass through checkpoints are missed. The present study was designed to determine the extent to which police officers correctly identify individuals with blood alcohol concentrations (BACs) at or above 0.05% at checkpoints, and if there are characteristics of drivers, vehicles or checkpoints that are associated with decreased chances of detection. METHOD: To determine which drivers are likely to be missed, drivers not detained by police for additional sobriety evaluation were interviewed and voluntary breath samples were provided at 156 sobriety checkpoints in North Carolina. RESULTS: More than 50% of the drivers with BACs in excess of 0.08% and almost 90% of drivers with BACs in excess of 0.05% were not detained by officers. For drivers with BACs of 0.05% or higher, women and those 35 or younger were more likely to be missed than were men and older drivers. Drivers without passengers were more likely to be missed than those with passengers. Drivers were also more likely to be missed during weekend checkpoints. Similar results were found for drivers with BACs at or above 0.08%. CONCLUSIONS: Alerting police officers to characteristics of drinking drivers more likely to be missed may improve detection rates. In addition, passive alcohol sensors could improve the effectiveness and efficiency of sobriety checkpoints in detecting drinking drivers.

Adolescent↗

Prenatal fumonisin (FB1) treatment in rats results in minimal maternal or offspring toxicity.

To investigate the neurobehavioral and developmental effects of the mycotoxin, FB1, Sprague-Dawley rats were treated with FB1 on gestational days 13-20. In Experiment 1, FB1 was obtained from culture material and pregnant rats were gavaged with 0, 0.8 or 1.6 mg/kg. In Experiment 2, pregnant rats were gavaged with purified FB1 at doses of 0, 1.6 or 9.6 mg/kg. Offspring were evaluated on a battery of behavioral tests as well as measures of whole and regional brain weight. There were no effects on maternal weight gain, reproductive outcomes, or offspring body weight through adulthood in either experiment. Complex maze performance, open field and running wheel activity were not altered by prenatal FB1 treatment. In Experiment 2, acoustic startle response was depressed at two ages during the first or second block of 9 trials in males treated with purified FB1. Females exhibited no such alterations. Play behavior at PND 33, but not PND 26, was increased in males prenatally treated with 9.6 mg/kg relative to those treated with 1.6 mg/kg. There were no substantive treatment effects on regional brain weight. These results suggest that doses of < or = 9.6 mg purified FB1/kg and/or < or = 1.6 mg FB1/kg obtained from culture material cause minimal maternal toxicity and produce few development functional alterations. In addition, potential FB1-related functional alterations were evident only in males providing further support for a mild sex-specific effect for fumonisin.

Animals↗

Serotonin agonists mimic the phase shifting effects of light on the melatonin rhythm in rats.

The effect of serotonin agonists on the rhythmic excretion of the melatonin metabolite 6-sulphatoxymelatonin was examined in rats. The animals were maintained in 12L:12D and administered saline, quipazine (10 mg/kg), (+/-)-2-propylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (8-OH-DPAT, 5 mg/kg) or buspirone (10 mg/kg), 4 h after dark (ZT16). All three drugs caused an acute, transient suppression of 6-sulphatoxymelatonin excretion and a significant delay (P < 0.01) in the onset of the nocturnal rise on the following night of 2.1 +/- 0.6, 1.4 +/- 0.7 and 1.5 +/- 0.3 h respectively while saline administration had no effect (0.4 +/- 0.2 h delay, P > 0.01). To examine the effects of the time of day of agonist administration, groups of rats were treated with quipazine (10 mg/kg) or 8-OH-DPAT (5 mg/kg) 18, 24 or 30 h after the initiation of continuous darkness (CT6, CT12 or CT18) and monitored for a further two nights. Quipazine but not 8-OH-DPAT injection at CT6 resulted in a small but significant delay in the onset of 6-sulphatoxymelatonin excretion on the following night (1.0 +/- 0.2 h and 0.3 +/- 0.2 h) while treatment with both agonists at CT12 failed to affect the onset of excretion (0.8 +/- 0.2 and 0.1 +/- 0.2 h). When quipazine (10 mg/kg) was administered at CT18, 6-sulphatoxymelatonin excretion was acutely suppressed for the rest of the night and there was a large significant delay in the onset of 6-sulphatoxymelatonin excretion (1.2 +/- 0.2 h) while a smaller delay was observed following 8-OH-DPAT administration (0.8 +/- 0.2 h). The acute suppression of 6-sulphatoxymelatonin excretion and subsequent phase delay following quipazine treatment at CT18 was also evident at doses of 1 mg/kg (1.6 +/- 0.4 h) and 3 mg/kg (1.5 +/- 0.6 h). These results show that peripheral administration of serotonin agonists active at 5HT1a/5HT7 receptors mimic the dual effects of light on melatonin production in the rat and raise the possibility that serotonin pathways are more important in mediating the effects of retinally perceived light in the rat than previously believed.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

Differences in young driver crash involvement in states with varying licensure practices.

Teenage driver licensing practices and the crashes of teenagers were compared in several states with differing laws and policies regarding licensure. High school seniors in Delaware, a state with laws that allow early driving and licensure, reported that they first drove on a public road, obtained a learner's permit and obtained a driver's license at younger ages than high school seniors in other northeastern states (Connecticut, New Jersey and upstate New York). State crash data indicated that Delaware and Connecticut, which allow unrestricted licensing at age 16, showed the highest rates of 16-year-old driver involvements in nonfatal and fatal injury crashes. Pennsylvania and upstate New York, which have night driving curfews for 16 year-olds, showed lower crash rates overall and much lower crash rates during their respective curfew hours. New Jersey and Nassau and Suffolk counties, where unsupervised driving by 16 year-olds is generally not allowed, showed the lowest crash rates for 16 year-olds. Graduated licensing programs that include delayed full-privilege licensure, night driving curfews, and extended periods of supervised practice driving are a possible countermeasure for the high motor vehicle crash rates of young drivers.

Accidents, Traffic↗

Effects of chlorpromazine and diazepam on time estimation behavior and motivation in rats.

The effects of chlorpromazine and diazepam on performance of two operant tasks, one modelling time estimation and the other motivation to work for food reinforcers, were investigated in rats. These same tasks had been used previously in rhesus monkeys to assess the effects of chlorpromazine and diazepam. Rat performance of the time estimation task [temporal response differentiation (TRD)] was nearly identical to that previously described in monkeys. This performance similarity across these two species occurred despite slightly different methodologies. Performance of the motivation task [progressive ratio (PR)] was clearly different between rats and adult monkeys in that rats exhibited lower values on all PR endpoints. Acute administration of chlorpromazine [0.03-5.6 mg/kg, intraperitoneally (IP)] caused decrements in rat TRD and PR performance at doses > or = 1.0 mg/kg. Acute administration of diazepam (0.25-4.0 mg/kg, IP) altered TRD performance only. The effects of chlorpromazine and diazepam in rats were similar to those previously noted in the monkey, indicating the potential utility of rat performance in these operant tasks to predict drug effects in the rhesus monkey.

Animals↗

Neuroanatomical and functional alterations resulting from early postnatal cerebellar insults in rodents.

This review examines neuroanatomical and functional alterations in rodents resulting from postnatal insults during cerebellar development. Treatments such as irradiation and methylazoxymethanol (MAM) administration produced near birth (< postnatal day 8 for irradiation treatment and < postnatal day 4 for MAM administration) result in more severe cerebellar damage than do similar treatments administered several days after birth. Prominent among the more severe alterations are foliation abnormalities, misalignment of Purkinje cells and continued multiple innervation of climbing fibers; few or none of these occur as a result of later treatments (> postnatal day 8 for irradiation treatment and > postnatal day 4 for MAM treatment). The functional alterations also differ: insults produced near birth result in hypoactivity, ataxia, tremor and accompanying learning deficits, whereas those produced later result in hyperactivity and few learning deficits. This hyperactivity may have relevance to human disorders. Brief discussions of cerebellar and functional alterations (e.g., hyperactivity) resulting from neonatal infection with the Borna disease virus and induction of hypo- and hyperthyroidism during the preweaning period are also presented.

Animals↗

Effects of ischemia-hypoxia induced by interruption of uterine blood flow on fetal rat liver and brain enzyme activities and offspring behavior.

The effects of acute perinatal ischemia-hypoxia on fetal liver and brain energy metabolism, fetal brain total free fatty acid concentration and subsequent offspring behavior were investigated in rats. Ischemia-hypoxia was induced at term either by ligation of the uterine blood vessels or submersion of the entire uterine horn in warmed saline. Fetuses of the adjacent horn served as within-dam controls for all assessments and fetuses of dams which had not undergone the surgical stress served as independent controls for enzyme assays. Ischemia-hypoxia was associated with reduced activity of fatty acid synthase in the liver and brain. Total free fatty acid concentration significantly increased in the fetal hypoxic brain. Pups not used for enzyme analyses were cross-fostered for behavioral assessments. Relative to the enzymatic alterations, there were few behavioral alterations associated with ischemia-hypoxia. At postnatal day 30, rats made hypoxic by ligation of the uterine blood vessels had decreased caudate nucleus and brain stem weights relative to within-dam controls. At postnatal day 85, rats made hypoxic by submersion of the uterine horn had decreased olfactory bulb weight. The results of this study indicate an initial acute response to a brief period of ischemia-hypoxia at term pregnancy in the fetal rat brain and liver.

Age Factors↗

The classification of anatomic- and symptom-based low back disorders using motion measure models.

STUDY DESIGN: This study observed the trunk angular motion features of healthy subjects and those experiencing chronic low back disorders as they flexed and extended their trunks in five symmetric and asymmetric planes of motion. Trunk angular position, velocity, and acceleration were evaluated during several cycles of motion. OBJECTIVE: The trunk angular motion features of the low back disorder group were normalized relative to the healthy subjects and used to 1) evaluate the repeatability and reliability of trunk motion as a measure of trunk musculoskeletal status, 2) quantify the extent of the disorder, 3) determine the extent to which trunk motion measures might be used as quantifiable means to help classify low back disorders. SUMMARY OF BACKGROUND DATA: Given the magnitude of the low back disorder problem, it is problematic that there are few quantitative methods for objectively documenting the extent of a disorder. Impairment ratings of low back disorders can vary by as much as 70% using current systems. Diagnoses and classification schemes are rarely based upon quantitative indicators and we are unable to easily assess and diagnose low back disorders. It is important to quantitatively evaluate low back disorders so that proper treatment can be administered and the risk of exacerbating the problem can be minimized. METHODS: Three-hundred-thirty-nine men and women between 20 and 70 years old who had not experienced significant back pain were recruited as the healthy subjects in this study. One hundred-seventy-one patients with various chronic low back disorders also were recruited and compared with the healthy group of subjects. All subjects wore a triaxial goniometer on their trunks that documented the angular position, velocity, and acceleration of the trunk as the subjects flexed and extended their trunks in each of five planes of motion. Trunk motion features first were normalized for subject gender and age. Several two-stage eight-variable models that account for trunk motion interactions were developed to classify the 510 healthy and low back injured subjects into one of 10 anatomic and symptom-based low back disorder classification categories. RESULTS: Using conservative cross-validation measures, it was found that the stage one eight-variable model could correctly classify more than 94% of the subjects as either healthy or having a low back disorder. One of the stage two eight-variable models was able to reasonably classify the patients with low back disorders into one of 10 low back disorder classification groups. CONCLUSION: The motion-related parameters may relate to biomechanical or learned sensitivities to spinal loading. This study suggests that higher-order trunk motion characteristics hold great promise as a quantitative indicator of the trunk's musculoskeletal status and may be used as a measure of the extent of a disorder and as a measure of rehabilitative progress. Furthermore, once the interactive nature of these trunk motion characteristics is considered, the model could help diagnose low back disorders. However, independent data sets are needed to validate these findings.

Adult↗

The effects of perinatal hypoxia on the behavioral, neurochemical, and neurohistological toxicity of the metabolic inhibitor 3-nitropropionic acid.

3-nitropropionic acid (3-NPA) neurotoxicity and long-term effects of perinatal hypoxia were evaluated in 18 adult rats. Hypoxia-insulted (I) and noninsulted (NI) rats were delivered by cesarean section. Hypoxic insult was effected by submerging dissected uterine horns in warmed saline for 15 min. NI rats were delivered from the adjacent nonsubmerged horns. At postnatal day 90, I and NI rats were trained to perform tasks thought to measure behaviors dependent upon aspects of time estimation (TE), motivation, and learning. At 12 months of age, rats were injected i.p. with escalating doses of 3-NPA (5 mg/kg/day to a maximum of 30 mg/kg/day) immediately after each test session and sacrificed at the end of treatment. Additional male rats were used as untreated controls. Although 3-NPA produced a dose-dependent impairment of performance in each task, the effects were qualitatively similar for each group. A significant difference between I and NI rats was, however, observed in the TE task where NI rats completed less of the task at high doses of 3-NPA compared to I rats. Compared to untreated controls, dopamine concentrations were decreased in caudate nucleus of both I and NI rats after 3-NPA. Specific areas most frequently damaged included cerebral cortex, hippocampal subfield CA1, thalamus, caudate nucleus, and the cerebellum. Lesions usually were less extensive in the I rather than NI members of a littermate pair, suggesting a possible protective effect of perinatal hypoxia against subsequent 3-NPA neurotoxicity.

Animals↗