PubMed Health⌕ Search

Biomedical subjects

J Howland

Publications and source records attributed to J Howland.

At least 19 recordsLinked to original sources
PubMed2001

Dorsal hippocampal kindling produces a selective and enduring disruption of hippocampally mediated behavior.

Kindling produces enduring neural changes that are subsequently manifest in enhanced susceptibility to seizure-evoking stimuli and alterations in some types of behavior. The present study investigated the effects of dorsal hippocampal (dHPC) kindling on a variety of behaviors to clarify the nature of previously reported effects on spatial task performance. Rats were kindled twice daily with dHPC stimulation until three fully generalized seizures were evoked. Beginning 7 d later and on successive days, rats were tested in an elevated plus maze, a large circular open field, an open field object exploration task, and a delayed-match-to-place (DMTP) task in a water maze to assess anxiety-related and activity-related behavior (tasks 1 and 2), object recognition memory (task 3), and spatial cognition (task 4). Kindling disrupted performance on the DMTP task in a manner that was not delay dependent and produced a mild enhancement of activity-related behaviors in the open field task but not the elevated plus maze. All other aspects of testing were spared. These findings indicate that dHPC kindling produces enduring and selective effects on behavior that are consistent with a restricted disruption of hippocampally mediated functions. Possible bases for these effects are changes in local NMDA receptor function and/or changes in local inhibition, which might alter the optimal conditions for experience-dependent induction of intrahippocampal plasticity. This preparation may be useful for studying the mechanisms of mnemonic dysfunction associated with temporal lobe epilepsy and may offer unique insights into the mechanisms underlying normal hippocampal function.

Animals↗
PubMed2001

Susceptibility to kindling and neuronal connections of the anterior claustrum.

The claustrum has been implicated in the kindling of generalized seizures from limbic sites. We examined the susceptibility of the anterior claustrum itself to kindling and correlated this with an anatomical investigation of its afferent and efferent connections. Electrical stimulation of the anterior claustrum resulted in a pattern of rapid kindling with two distinct phases. Early kindling involved extremely rapid progression to bilaterally generalized seizures of short duration. With repeated daily kindling stimulations, early-phase generalized seizures abruptly became more elaborate and prolonged, resembling limbic-type seizures as triggered from the amygdala. We suggest that the rapid rate of kindling from the anterior claustrum is an indication that the claustrum is functionally close to the mechanisms of seizure generalization. In support of our hypothesis, we found significant afferent, efferent, and often reciprocal connections between the anterior claustrum and areas that have been implicated in the generation of generalized seizures, including frontal and motor cortex, limbic cortex, amygdala, and endopiriform nucleus. Additional connections were found with various other structures, including olfactory areas, nucleus accumbens, midline thalamus, and brainstem nuclei including the substantia nigra and the dorsal raphe nucleus. The anatomical connections of the anterior claustrum are consistent with its very high susceptibility to kindling and support the view that the claustrum is part of a forebrain network of structures participating in the generalization of seizures.

Afferent Pathways↗
PubMed2001

Initial sequencing and analysis of the human genome.

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Animals↗
PubMed2001

Effects of low-dose alcohol exposure on simulated merchant ship piloting by maritime cadets.

The US Department of Transportation (DOT) regulates on-the-job alcohol use by operators of certain categories of commercial transport. For aircraft, trains, and commercial vessels, operators are subject to sanctions for having > or = 0.04 g% blood alcohol concentration (BAC). This study examines the effects of alcohol (between 0.04 and 0.05 g% BAC) on simulated merchant ship handling. A two-group randomized factorial design was used to compare beverage alcohol to placebo while controlling for baseline performance on a previous day. The study was conducted in the Maritime Simulation Center at Maine Maritime Academy, Castine, ME. Participants were 38 volunteer deck officer cadets in their junior or senior year, at least 21 years of age, with previous experience on a bridge simulator. Following a baseline trial on Day 1, on Day 2 participants were randomized to receive alcohol (0.6 g/kg for males and 0.5 g/kg for females) or placebo. After allowing time for absorption, participants completed a bridge simulator task. For baseline and performance trials, participants were randomized to one of four bridge simulator scenarios, each representing passage of a fully loaded container vessel through a channel with commercial traffic. The aggregate scenario score given by blinded maritime educators measured performance. A main effect for alcohol was found indicating that performance was significantly impaired by this low dose of alcohol relative to performance in the placebo condition. These findings are consistent with current federal regulations that limit low-dose alcohol exposure for the operators of commercial transport vehicles. Further research is required to determine effects at lower BACs.

Adult↗
PubMed2001

Personal values and sexual decision-making among virginal and sexually experienced urban adolescent girls.

PURPOSE: To guide the development of an intervention to reduce the incidence of sexually transmitted diseases (STDs) in urban, adolescent girls, we investigated such girls' reasons for deciding to have or not to have sexual intercourse. METHODS: Consecutive girls >or=14 years of age attending an urban adolescent clinic were invited to complete an anonymous survey about sexual decision-making. In this pilot study, girls were asked: (a) whether they agreed with a statement that they had or had not had sexual intercourse "because of my values and beliefs"; and (b) to select from a list one or more specific reasons why they had or had not had intercourse. The girls were categorized by self-report as either "virgins," "currently inactive" (no intercourse in the preceding 3 months), or "currently active" (had intercourse during the preceding 3 months). RESULTS: Usable surveys were obtained from 197 adolescents whose age (18.2 +/- 2.6 years) and race (69% black) were comparable to those of clinic attendees in general. Forty girls (20%; age 16.1 +/- 2.1 years) were virgins, 25 girls (13%; age 17.8 +/- 2.3 years) were inactive, and 132 girls (67%; age 18.9 +/- 2.5 years) were currently active. "Values and beliefs" were cited as the reason for decisions about sexual behavior by 53% of the virgins, but only by 24% of the sexually inactive and 24% of the sexually active girls (p = .002). Virgins were more likely than inactive girls to cite three specific reasons for not having sex: "not the right thing for me now" (82% vs. 50%, p = .007), "waiting until I am older" (69% vs. 8%, p = .001), and "waiting until I am married" (67% vs. 38%, p = .02). The reason "against my religious beliefs" was cited by 23% of virgins and 13% of inactive girls (p = not significant). Personal values were implicit in the two specific reasons for having sex that active girls chose most frequently, namely, "I like/love the person" (86%) and "I like having sex" (37%), although only 24% of these girls had explicitly cited "values and beliefs" as their reason for having sex. CONCLUSIONS: Our data indicate that urban girls, both those who have had sexual intercourse and those who have not, view their sexual behavior as being based on personal (although infrequently religious) values. Many of the virginal urban, adolescent girls we surveyed hold abstinence as a personal value. The sexually active adolescents perceive the decision to have sexual intercourse as being based affirmatively on their personal values rather than on the chance occurrence of opportunities to have intercourse. These data may be useful in the development of new strategies for reducing urban adolescent girls' risk of acquiring sexually transmitted diseases.

Adolescent↗
PubMed2000

Age of drinking onset and unintentional injury involvement after drinking.

CONTEXT: In 1997, unintentional injury was the leading cause of death for persons aged 1 to 34 years. Approximately one third of deaths due to unintentional injury in the United States are estimated to be alcohol related. Onset of drinking at an early age has been found to be associated with alcohol dependence, but whether early-onset drinking increases risk for unintentional injury while drinking is unknown. OBJECTIVE: To explore whether persons who started drinking at an early age are more likely to have experienced unintentional injuries while under the influence of alcohol. DESIGN AND SETTING: The National Longitudinal Alcohol Epidemiology Survey, a cross-sectional survey conducted in 1992 of a representative sample of the US population. PARTICIPANTS: A total of 42,862 randomly selected adults (response rate, 90%; mean age, 44 years). MAIN OUTCOME MEASURES: Unintentional injury involvement while under the influence of alcohol by age of drinking onset (categorized as <14 years, each age from 14-20 years, or >/=21 years). RESULTS: Relative to respondents who began drinking at age 21 years or older, those who started before age 14 years as well as those who started at each intervening age up to 21 years were significantly more likely to have been injured while under the influence of alcohol, even after controlling for history of alcohol dependence, heavy drinking frequency during the period that they drank most, family history of alcoholism, and other characteristics associated with earlier onset of drinking. After adjusting for these variables, odds ratios for having been injured while under the influence of alcohol were as follows: for younger than 14 years, 2.98 (95% confidence interval [CI], 2.29-3.89); age 14 years, 2.96 (95% CI, 2.26-3.88); age 15 years, 3.14 (95% CI, 2.48-3.97); age 16 years, 2.38 (95% CI, 1.90-2.98); age 17 years, 2.12 (95% CI, 1.66-2.71); age 18 years, 1. 33 (95% CI, 1.08-1.64); age 19 years, 1.42 (95% CI, 1.07-1.89); and age 20 years, 1.39 (95% CI, 1.01-1.91). CONCLUSION: Drinking onset at ages younger than 21 years is associated with having experienced alcohol-related injuries. JAMA. 2000;284:1527-1533

Accidents↗
PubMed2000

Effects of low-dose alcohol exposure on simulated merchant ship handling power plant operation by maritime cadets.

AIMS: Under current US Department of Transportation (DOT) regulations, some commercial vehicle operators are subject to sanctions for having > or = 00.04 g% blood alcohol concentrations (BACs) on the job. This study investigated the effects of alcohol (between 0.04 and 0.05 g% BAC) on the simulated operation of a commercial ship's power plant. DESIGN: A balanced placebo design was used in which alcohol administration was fully crossed with expectancy that alcohol was administrated. SETTING: The study was conducted at the Massachusetts Maritime Academy, Buzzards Bay, MA, USA. PARTICIPANTS: Participants were 18 volunteer engineering students in their senior year, at least 21 years of age, with previous experience on the diesel simulator. INTERVENTION: Following a baseline trial on day 1, on day 2 participants were randomized to expectancy (told alcohol or placebo) and beverage (receive alcohol or placebo). The dosage was 0.6 g/kg for males and 0.5 g/kg for females. In both baseline and performance days, participants were randomized to one of four diesel simulator scenarios, each replicating a system failure in a power plant subsystem (e.g. main propulsion, electrical generating). MEASUREMENT: Performance was measured by time required for problem identification and remediation. FINDINGS: A main effect for alcohol administration was found. In the alcohol condition, simulator performance time was almost twice as long (351 sec) as on the placebo condition (186 sec). The expectancy effect was not significant. CONCLUSION: These findings support the current federal policy on the hazards of this low alcohol level within the context of commercial shipping.

Adult↗
PubMed2000

Boater training, drinking and boating, and other unsafe boating practices.

OBJECTIVES: Identify associations between lack of formal boater training, drinking and boating, and other unsafe boating practices. METHODS: A telephone survey queried respondents (age 16 or older in continental United States) about boating experience, type of boat used, and training. RESULTS: Of the 3,042 boaters surveyed (70% response), most had no formal training (73%). Boaters with formal training failed to use PFDs about as often as those without formal training and were equally or more likely to use alcohol while boating. CONCLUSIONS: The unexpected association between formal training and unsafe boating practices is probably due to reduced risk perception and inadequacies of boater training programs. Such programs seldom mention the risks of alcohol use while boating. Decisions to mandate formal training should be informed by these results; if mandated, training should address the risks of alcohol use while boating, and should be renewed frequently enough to offset reductions in risk perception.

Adult↗
PubMed1999

Employee drinking practices and work performance.

OBJECTIVE: The purpose of this study was to examine the independent effects of a variety of drinking indicators on self-reported work performance. METHOD: Data from a cross-sectional mailed survey (response rate = 71%) of managers, supervisors and workers (N = 6,540) at 16 worksites were analyzed. Average daily volume was computed from frequency and usual quantity reports. Drinking on the job included drinking during any of six workday situations. The CAGE was used to indicate alcohol dependence. Employees were also asked how frequently they drank to get high or drunk. Work performance was measured through a series of questions about work problems during the prior year. The number of times respondents experienced work performance problems was regressed on the four drinking measures, and a variety of demographic characteristics, job characteristics and life circumstances that might also negatively affect work performance. RESULTS: The frequency of self-reported work performance problems increased, generally, with all four drinking measures. In a multivariate model that controlled for a number of demographics, job characteristics and life-situations, average daily volume was no longer significantly associated with work performance but the other three drinking measures were. Interestingly, although moderate-heavy and heavy drinkers reported more work performance problems than very light, light, or moderate drinkers, the lower-level-drinking employees, since they were more plentiful, accounted for a larger proportion of work performance problems than did the heavier drinking groups. CONCLUSIONS: Employers should develop clear policies limiting drinking on the job and, in addition to employee assistance programs for problem drinkers, should develop worksite educational interventions aimed at informing all employees about the relationship between drinking behaviors and work performance.

Absenteeism↗
PubMed1998

Fear of falling and activity restriction: the survey of activities and fear of falling in the elderly (SAFE).

A new instrument was developed to assess the role of fear of falling in activity restriction. The instrument assesses fear of falling during performance of 11 activities, and gathers information about participation in these activities as well as the extent to which fear is a source of activity restriction. The instrument demonstrated good internal consistency reliability and showed convergent validity with other fear of falling measures. Concurrent (empirical) validity was demonstrated in that the scale was effective in differentiating among those who were expected to be afraid vs. not afraid of falling. Criterion validity was examined in relation to quality of life variables. Fear of falling was shown to be related to lower quality of life, even when controlling for related background factors. One advantage of this measure over existing measures is the possibility for differentiating fear of falling that leads to activity restriction from fear of falling that accompanies activity. This may provide useful information for those interested in treating fear of falling of promoting activity among the elderly.

Accidental Falls↗
PubMed1998

A randomized, controlled trial of a group intervention to reduce fear of falling and associated activity restriction in older adults.

A randomized, single-blind controlled trial was conducted to test the efficacy of a community-based group intervention to reduce fear of falling and associated restrictions in activity levels among older adults. A sample of 434 persons age 60+ years, who reported fear of falling and associated activity restriction, was recruited from 40 senior housing sites in the Boston metropolitan area. Data were collected at baseline, and at 6-week, 6-month, and 12-month follow-ups. Compared with contact control subjects, intervention subjects reported increased levels of intended activity (p < .05) and greater mobility control (p < .05) immediately after the intervention. Effects at 12 months included improved social function (p < .05) and mobility range (p < .05). The intervention had immediate but modest beneficial effects that diminished over time in the setting with no booster intervention.

Accidental Falls↗
PubMed1998

Covariates of fear of falling and associated activity curtailment.

With a sample survey (N = 266) of elderly adults residing in six housing developments in Massachusetts, we used logistic regression to: (a) identify covariates of fear of falling among all subjects and (b) identify covariates of activity curtailment among the subset of subjects who were afraid of falling. Fifty-five percent of respondents were afraid of falling; of those who were afraid, 56% had curtailed activity due to this fear. Factors associated with fear of falling were: being female, having had previous falls, and having fewer social contacts. Factors associated with activity curtailment among those who were afraid were: not communicating about falls; having less social support; and knowing someone who had fallen. Falls history appears an important contributor to fear of falling, whereas the impact of this fear on activities appears more a function of social support. These findings suggest different strategies for the primary and secondary prevention of fear of falling.

Accidental Falls↗
PubMed1998

Did changes in minimum age drinking laws affect adolescent drowning (1970-90)?

OBJECTIVE: To test the hypothesis that changes in the minimum legal drinking age (MLDA) laws would affect drowning among adolescents, the effects of changes in state MLDA laws on drowning were examined for the targeted (18-20 years) and two adjacent (15-17 years and 21-23 years) age groups, over a period of 21 years (1970-90). METHODS: Poisson maximum likelihood regression was used to estimate the effects of both lowering and increasing the MLDA. The dependent variable in these analyses was the number of drownings per state per year for the age groups observed. At first only state and year effects were controlled for and then any other variable potentially associated with the incidence of drowning was included. The other control variables included proportion of population living near border states with lower MLDA laws, urbanicity, unemployment, divorce, education, poverty, beer tax, and proxy measures for MLDA law enforcement. RESULTS: No significant association between drowning and MLDA was found for any of the age groups studied. CONCLUSION: It is concluded that MLDA laws are not an important public policy strategy for affecting drowning rates among adolescents and young adults.

Adolescent↗
PubMed1998

Intensity and correlates of fear of falling and hurting oneself in the next year: baseline findings from a Roybal Center fear of falling intervention.

Fear of falling is highly prevalent and associated with restricted activity. To help inform design of interventions, the authors examined the correlates of this fear. Data came from baseline information on subjects in a community-based falls intervention study (N = 392). In a multivariate model, lower levels of fear of falling and hurting oneself in the next year were related to being younger, having higher levels of dysfunction, and having lower levels of perceived ability to manage falls, with the last two remaining significant even after controlling for generalized fearfulness. When analyzing specific domains of dysfunction, higher levels of fear of falling and hurting oneself in the next year were associated with higher levels of physical dysfunction. The findings lend support to the expanding awareness that fear of falling may imperil quality of life and suggest the importance of interventions aimed at enhancing ability to manage falls.

Accidental Falls↗
PubMed1997

Sunbathing habits and sunscreen use among white adults: results of a national survey.

OBJECTIVES: This study assessed current levels of sunbathing and sunscreen use in the United States. METHODS: From a general-population telephone survey of aquatic activities among adults in 3042 US households, we examined responses by the 2459 Whites. RESULTS: Most adults (59%) reported sunbathing during the past year, and 25% reported frequent sunbathing. Of the subsample who reported sunbathing during the month before the interview, 47% routinely used sunscreen. Of these individuals, almost half did not use sunscreens with a solar protection factor of 15 or higher. CONCLUSIONS: About a quarter of US White adults report frequent sunbathing, and only about a quarter of sunbathers use sunscreens at recommended levels. These results should help focus future sun protection educational efforts.

Adolescent↗
PubMed1997

State-level clustering of safety measures and its relationship to injury mortality.

This article proposes a social model of investigating injury mortality. The authors hypothesize that (1) state-level laws and regulations on safety cluster together in one or more groupings; (2) groupings of safety measures play a significant role in injury mortality; and (3) injury mortality is very highly associated with social structural variables. There is a clustering of safety policies, with five factors explaining 67 percent of variance, although no "master factor" was discovered. The strongest factor, explaining 21 percent of variance, includes three gun laws and low speed limits before the 1973 federal law. One factor is the most global in that it taps three distinct areas, including helmet laws, minor blood alcohol levels, and smoke detectors, though it only explains 7.5 percent of variance. The only factor that remains in a regression for injury mortality is one that includes strong seat belt laws and strong enforcement of those laws, though in the direction opposite to that hypothesized. This factor, along with percentage rural and environmental spending per capita, is significant for both motor vehicle and non-motor vehicle mortality. For motor vehicle mortality alone, deaths are higher in states with higher percentages of Hispanics and fewer people receiving food stamps and AFDC. Many factors that usually predict individual injury mortality do not hold at the state level, suggesting the usefulness of looking at social factors for new insights into injury mortality and prevention.

Adolescent↗