Higher strains in the inner region of the meniscus indicate a potential source for degeneration.

Complex structural properties of menisci can be characterized in part by their inhomogeneous strain response under compression. This pilot study explored the feasibility to quantify characteristic strain distributions on meniscus cross-sections subjected to static compression using electronic speckle pattern interferometry (ESPI). Cross-sectional specimens of 5-mm thickness were harvested from eight human menisci. After application of 20% pre-strain, strain maps in response to 10µm compression were captured with ESPI. The 10µm compression induced an aggregate strain of nominally 0.14% and resulted in highly non-uniform strain distributions. Local compressive strain captured by ESPI ranged from 0.03% to 0.7%. The highest strain was in the central region of meniscus cross-sections, and the lowest magnitude of strain was at the femoral surface of the meniscus. After stratifying for age, peak compressive strain in older menisci (71±6 years, n=4) was 0.33%±0.09, compared to 0.25%±0.06 in younger menisci (34±9 years, n=4). In conclusion, this study captured for the first time continuous strain distribution maps over entire meniscus cross-sections. The non-uniform strain distributions demonstrated inhomogeneous structural properties. Age-related differences in characteristic strain distributions likely represent degenerative changes. As such, ESPI provides a novel strategy of further characterize meniscal function and degeneration.

Effects of sampling standardization on estimates of Phanerozoic marine diversification.

Global diversity curves reflect more than just the number of taxa that have existed through time: they also mirror variation in the nature of the fossil record and the way the record is reported. These sampling effects are best quantified by assembling and analyzing large numbers of locality-specific biotic inventories. Here, we introduce a new database of this kind for the Phanerozoic fossil record of marine invertebrates. We apply four substantially distinct analytical methods that estimate taxonomic diversity by quantifying and correcting for variation through time in the number and nature of inventories. Variation introduced by the use of two dramatically different counting protocols also is explored. We present sampling-standardized diversity estimates for two long intervals that sum to 300 Myr (Middle Ordovician-Carboniferous; Late Jurassic-Paleogene). Our new curves differ considerably from traditional, synoptic curves. For example, some of them imply unexpectedly low late Cretaceous and early Tertiary diversity levels. However, such factors as the current emphasis in the database on North America and Europe still obscure our view of the global history of marine biodiversity. These limitations will be addressed as the database and methods are refined.

Binge drinking, sensible drinking, and abstinence after alcohol-related vehicular crashes: the role of intervention versus screening.

Brief interventions have been shown to reduce problem drinking in a variety of populations and settings. The hypothesis for our randomized trial was that individuals injured in alcohol-related crashes who received a more intensive intervention (brief counseling) would have reduced binge drinking as compared to those with a less intensive intervention (simple advice) and controls. Non-alcohol dependent, seriously injured individuals (N = 186) were enrolled in the protocol. At baseline, mean binges/month (b/m) were 5.88 and at 12 months were 2.02 b/m. Although there was no significant difference by condition, at 12 months the brief counseling group had the lowest rate of binge drinking (1.97 b/m). Whether these drinking patterns were a result of the crash, injury, screening for alcohol use, or combination of these factors is difficult to determine.

Validity of self-reported alcohol consumption in nondependent drinkers with unintentional injuries.

BACKGROUND: Self-report has become an anchor for alcohol assessment in the acute and primary care populations. The purpose of the study was to determine the validity of self-reported alcohol consumption after unintentional injuries in hospitalized, nondependent drinkers. METHODS: Non-alcohol-dependent subjects 18 years of age and older with unintentional injuries (n = 209) were enrolled in the study and were interviewed if they had either an admitting blood alcohol concentration (BAC) > or = 10 mg/dl (0.01 g/dl) or a positive screen for a history of problem drinking. The self-reported number of standard drinks, time that drinking commenced, sex, and weight were used to calculate estimated blood alcohol concentration (EBAC), which was then compared to the admission BAC. RESULTS: We had data to calculate the EBAC on 141 of the 209 subjects. Seven men and no women with positive (> or = 10 mg/dl) BAC denied drinking. Of the 134 subjects for whom we had data to calculate EBAC and who acknowledged drinking, mean BAC was 147.06 mg/dl and mean EBAC was 68.66 mg/dl. For women (n = 30), mean BAC was 149.53 mg/dl and mean EBAC was 114.67 mg/dl; for men (n = 104), mean BAC was 146.35 mg/dl and mean EBAC was 55.38 mg/dl. The Spearman's p between laboratory BAC and EBAC was 0.461 (p < 0.001) for all subjects (n = 134), 0.275 (NS) for women (n = 30), and 0.532 (p < 0.001) for men (n = 104). For women and men separately, multiple regression analyses were performed to predict BAC by using weight and reported number of drinks. For women, weight and number of drinks accounted for 3% of the variance in laboratory BAC [r = 0.181, F(2,47) = 0.797,p = NS]. In contrast, for men these same predictors accounted for 34% of the variance [r = 0.585, F(2,135) = 35.203,p < 0.001). CONCLUSIONS: Most nondependent patients with unintentional injury acknowledged drinking before injury. After injury, women and men have different patterns of reporting their drinking, with men more frequently underreporting but reporting more accurately and women more random in their self-reports.

Direct comparison of auditory implicit memory tests.

In this experiment, we examined the degree to which four implicit tests and two explicit tests, all involving auditory presentation, were sensitive to the perceptual characteristics of the stimuli presented during study. Presenting stimuli visually decreased priming in all the implicit memory tests, relative to auditory presentation. However, changing voice between study and test decreased priming only in the implicit memory tests requiring identification of words degraded by noise or by low-pass filtering, but not in those tests requiring generation from word portions (stems and fragments). Modality effects without voice effects were observed in cued recall, but the opposite pattern of results (voice effects without modality effects) was obtained in recognition. The primary new finding is the demonstration that auditory memory tests, both explicit and implicit, differ in their sensitivity to the perceptual information encoded during study.

Auditory habituation in young and older adults: the verbal transformation effect.

In 3 experiments, auditory massed repetition was used to examine age-related differences in habituation by means of the verbal transformation paradigm. Participants heard 10 words (5 high frequency and 5 low frequency), each presented 180 times, and they reported perceived changes in the repeated words (verbal transformations). In these experiments, older adults reported fewer illusory percepts than young adults. Older adults' loss of auditory acuity and slowing of processing, stimulus degradation (in young adults), and instructions biasing the report of these illusory percepts did not account for the fewer illusory percepts reported by the older adults. These findings suggest that older adults' reduced susceptibility to habituation arises from centrally located declines in the transmission of information within the word-recognition pathway. The discussion focuses on the implications that these age-related declines may have on word identification during on-line speech perception.

Attribution of injury to alcohol involvement in young adults seriously injured in alcohol-related motor vehicle crashes.

BACKGROUND: Approximately 40% of all traffic fatalities are associated with the use of alcohol. Hospitalization for serious injury after a motor vehicle crash related to use of alcohol may be an opportunity to change drinking behaviors in non-alcohol-dependent drinkers, thereby reducing the risk for future disability and death. OBJECTIVES: To determine the degree to which non-alcohol-dependent adults aged 18 to 45 years with alcohol-related vehicular trauma attributed their injury to use of alcohol. METHODS: During hospitalization, 132 subjects involved in alcohol-related motor vehicle crashes were interviewed. The interviews included the question, "To what extent do you believe your alcohol consumption was responsible for this injury?" Responses were measured on a 7-point scale ranging from 1 (not at all) to 7 (totally). RESULTS: In response to the question about attribution of injury to alcohol, 37.8% of subjects responded "not at all," 24.3 responded "somewhat," and 37.9% responded "mostly" or "totally." Spearman rank correlation between attribution of injury to alcohol involvement and blood alcohol content at admission was r = 0.440 (P < .001). CONCLUSIONS: More than 60% of patients injured in alcohol-related motor vehicle crashes attributed their injury partly or totally to use of alcohol. When alcohol-free, hospitalized patients with higher blood levels of alcohol on admission were more likely than those with lower levels to attribute their injury to alcohol. Hospitalization for a motor vehicle crash related to use of alcohol provides an opportunity for interventions to decrease drinking.

The effects of talker familiarity on spoken word identification in younger and older listeners.

The present study was designed to examine age differences in the ability to use voice information acquired intentionally (Experiment 1) or incidentally (Experiment 2) as an aid to spoken word identification. Following both implicit and explicit voice learning, participants were asked to identify novel words spoken either by familiar talkers (ones they had been exposed to in the training phase) or by 4 unfamiliar voices. In both experiments, explicit memory for talkers' voices was significantly lower in older than in young listeners. Despite this age-related decline in voice recognition, however, older adults exhibited equivalent, and in some cases greater, benefit than young listeners from having words spoken by familiar talkers. Implications of the findings for age-related changes in explicit versus implicit memory systems are discussed.

Age differences in backward masking.

The present study was designed to assess the effects of age on the time course of backward masking. In experiment 1, thresholds for detecting a 10-ms, 500-Hz sinusoidal signal were measured as a function of the temporal separation between the signal and a 50-ms broadband masker. Subjects were younger (18-24) and older (over age 65) adults with normal hearing (thresholds less than 20 dB HL) for frequencies of 4 kHz and below. Younger subjects exhibited less overall masking and steeper recovery functions than did the older adults. Masked thresholds for younger participants approached unmasked thresholds for signal-masker delays greater than 6-8 ms. In contrast, older adults exhibited significant masking even at the longest delay tested (20 ms). In experiment 2, signal duration was decreased to 5 ms for a separate group of younger adults. Although overall thresholds were elevated for the shorter signal duration, the slope of the backward masking recovery function was not different from that observed for younger adults in experiment 1. The results suggest that age, independent of hearing loss, affects the temporal course of backward masking.

Perceptual specificity and implicit auditory priming in older and younger adults.

Age differences in perceptual specificity for implicit auditory priming were examined in 3 experiments. All 3 experiments began with a study phase during which participants rated words based on perceptual (shallow encoding) or semantic (deep encoding) attributes. After the study phase, participants were asked to identify filtered versions of repeated and new words (implicit test) and then to make old/new recognition judgments (explicit test). In contrast to earlier findings (D. L. Schacter, B. Church, & D. M. Osowiecki, 1994), older and younger adults were equally sensitive to study-to-test changes in speaking rate (Experiment 1), fundamental frequency (Experiment 2), and voice (Experiment 3). Explicit memory, in contrast, was significantly poorer for older adults but was minimally affected by changes in surface features. Findings from the study are discussed with respect to their implications for establishing the mechanisms mediating perceptual specificity and for their importance in understanding age-related changes in implicit memory.

Inhibitory processes and spoken word recognition in young and older adults: the interaction of lexical competition and semantic context.

Two experiments were conducted to examine the importance of inhibitory abilities and semantic context to spoken word recognition in older and young adults. In Experiment 1, identification scores were obtained in 3 contexts: single words, low-predictability sentences, and high-predictability sentences. Additionally, identification performance was examined as a function of neighborhood density (number of items phonetically similar to a target word). Older adults had greater difficulty than young adults recognizing words with many neighbors (hard words). However, older adults also exhibited greater benefits as a result of adding contextual information. Individual differences in inhibitory abilities contributed significantly to recognition performance for lexically hard words but not for lexically easy words. The roles of inhibitory abilities and linguistic knowledge in explaining age-related impairments in spoken word recognition are discussed.

Foundations of genetics: genetic structure, function, and therapeutics.

Molecular genetics provides the basis for understanding patterns of health and disease in people and is part of the scientific foundation on which acute and critical care nurses should build their practice. The human genome, defined as all the genetic information in the cells of humans, provides the blueprint for protein production and cellular function in the body. Alterations in protein production may result in illness or organ malfunction that has a genetic derivation. One therapeutic strategy that holds promise to manage genetic diseases is gene therapy. Gene therapy, or human gene transfer, occurs when scientists or physicians modify the genetic material in cells for therapeutic purposes. Genetic structure, function, and therapeutic reflect the science of the present and future and have profound practice implications for acute and critical care nurses.

Molecular genetics: from bench to bedside.

Diligent work performed at the laboratory bench during the 20th century has resulted in advances in the health care industry and benefits for the patients it serves. Time-saving laboratory techniques such as DNA isolation and polymerase chain reaction (PCR) have helped molecular biologists and geneticists learn more about genes and their function. Information resulting from genetic research is currently used by medical researchers to develop genetic testing, genetic engineering, and gene therapy procedures that will benefit patients with genetic needs. This article provides basic information regarding several of these procedures, including DNA isolation, PCR, gel electrophoresis, and restriction enzyme techniques. In addition, the article explores the experiences of a clinical nurse, who by learning genetic laboratory techniques, developed an appreciation of the nursing implications related to genetic laboratory procedures.

Brief intervention after alcohol-related injuries.

Brief intervention is a clinically-based, cost effective, time efficient intervention designed to counsel nondependent drinkers about strategies to reduce their alcohol consumption. The ultimate goal of brief intervention is to prevent future alcohol-related injury and health problems. This focused and time limited intervention is designed for use by health care providers in their ongoing daily practice. Patients who recently experienced an alcohol-related injury are particularly receptive to brief intervention.

Auditory suppression and frequency selectivity in older and younger adults.

Age differences in auditory suppression were examined by comparing auditory-filter shapes obtained with simultaneous and forward masking at 2 kHz in young and elderly normal-hearing listeners. To compensate for the decay of forward masking, growth of masking functions were used to transform thresholds obtained with a notched-noise masker to the level of a continuous noise band that would give the same threshold values. Although both age groups exhibited smaller equivalent rectangular bandwidths (ERBs) when the filters derived from transformed thresholds were obtained with forward masking, the change from simultaneous to nonsimultaneous masking was significantly greater for young adults. Measures of the low- (Pl) and high- (Pu) frequency sides of the filters for young listeners indicated that the slopes of both sides increased following a change from simultaneous to forward masking but that the high-frequency side exhibited significantly greater sharpening. Filter slopes (both upper and lower) for older adults, in contrast, did not differ between the two masking procedures. The findings from the study are discussed as reflecting possible age differences in auditory suppression. However, it is also noted that conclusions regarding differences between filter shapes derived with simultaneous and forward masking are limited to filter parameters determined with transformed (as described above) thresholds.

Spoken word recognition in individuals with dementia of the Alzheimer's type: changes in talker normalization and lexical discrimination.

Four experiments were conducted to examine the effects of dementia of the Alzheimer's type (DAT) on talker normalization and lexical discrimination. Talker normalization has been proposed as the principal mechanism underlying listeners' ability to maintain perceptual constancy for speech signals. Lexical discrimination refers to the ability to distinguish individual words from phonetically similar items stored in the mental lexicon. Healthy older adults served as controls. Comparisons of controls and very mildly impaired patients with DAT revealed no significant change in either lexical discrimination or talker normalization. In contrast, individuals with more advanced DAT (mildly demented) exhibited significant declines in both abilities. The results are discussed with respect to the possible roles of general slowing and inhibitory declines as factors affecting speech perception in DAT.

Sensitive topics and adolescents: making research about risk behaviors happen.

This article discusses conducting research with adolescents as a positive experience, both from a clinical and scholarly perspective. However, topics involving risk-taking behaviors may be especially difficult for adolescents to discuss openly. To implement research protocols with the adolescent population, particularly when dealing with risk-taking behaviors, investigators need to be aware of developmental challenges that warrant specific methodological choices. In a pilot study that involved adolescents who had been hospitalized for traumatic injury, the researchers gained valuable experience in conducting a study on substance use. Experiences with the study provide direction for future research about investigating sensitive topics with adolescents.