Aging and the neural correlates of successful picture encoding: frontal activations compensate for decreased medial-temporal activity

We investigated the hypothesis that increased prefrontal activations in older adults are compensatory for decreases in medial-temporal activations that occur with age. Because scene encoding engages both hippocampal and prefrontal sites, we examined incidental encoding of scenes by 14 young and 13 older adults in a subsequent memory paradigm using functional magnetic resonance imaging (fMRI). Behavioral results indicated that there were equivalent numbers of remembered and forgotten items, which did not vary as a function of age. In an fMRI analysis subtracting forgotten items from remembered items, younger and older adults both activated inferior frontal and lateral occipital regions bilaterally; however, older adults showed less activation than young adults in the left and right parahippocampus and more activation than young adults in the middle frontal cortex. Moreover, correlations between inferior frontal and parahippocampal activity were significantly negative for old but not young, suggesting that those older adults who showed the least engagement of the parahippocampus activated inferior frontal areas the most. Because the analyses included only the unique activations associated with remembered items, these data suggest that prefrontal regions could serve a compensatory role for declines in medial-temporal activations with age.     

Neuromuscular adaptations to spaceflight are specific to postural muscles

The effects of microgravity were determined in muscles of differing function and myofiber-type composition. Rats were assigned either to a 10-day spaceflight mission or to ground-based control conditions. Following the experimental period, hindlimb muscles were obtained from both groups. Cytofluorescent techniques were used to examine neuromuscular junctions (NMJs) from both slow- and fast-twitch fibers. Histochemical procedures were employed to assess myofiber profiles (size and type). Results indicate that microgravity did not alter NMJ structure or myofiber profile in the tibialis anterior, a predominantly fast-twitch, nonpostural muscle. Similarly, the NMJs and myofibers of deep regions of the gastrocnemius, a locomotor muscle possessing a mixed fiber population, were unaffected by spaceflight. In contrast, both myofibers and NMJs of the soleus-a postural muscle-demonstrated significant (P < 0.05) plasticity following exposure to spaceflight. Moreover, NMJs of both fast- and slow-twitch myofibers displayed similar remodeling in that muscle. Our findings suggest that the deleterious effects of microgravity are most apparent among postural muscles, and are manifested both in myofibers and their synapses.     

The accuracy and reliability of measurements made on computer-based digital models

For reasons of convenience and economy, orthodontists who routinely use and maintain pre- and posttreatment plaster casts are beginning to use computer-based digital models. The purpose of this study was to determine the accuracy (validity), reproducibility (reliability), efficacy, and effectiveness of measurements made on computer-based models. A plastic model occlusion ie, dentoform, served as a gold standard to evaluate the systematic errors associated with producing either plaster or computer-based models. Accuracy, reproducibility, efficacy, and effectiveness were tested by comparing the measurements of the computer-based models with the measurements of the plaster models--(1) accuracy: one examiner measuring 10 models made from a dentoform, twice; (2) reproducibility and efficacy: two examiners measuring 50 models made from patients, twice; and (3) effectiveness: 10 examiners measuring 10 models made from patients, twice. Reproducibility (reliability) was tested by using the intraclass correlation coefficient. Repeated measures of analysis of variance for multiple repeated measurements and Student's t-test were used to test for validity. Only measurements of maxillary and mandibular space available made on computer-based models differed from the measurements made on the dentoform gold standard. There was significantly greater variance for measurements made from computer-based models. Reproducibility was high for measurements made on both computer-based and plaster models. In conclusion, measurements made from computer-based models appear to be generally as accurate and reliable as measurements made from plaster models. Efficacy and effectiveness were similar to those of plaster models. Therefore, computer-based models appear to be a clinically acceptable alternative to conventional plaster models.     

Effects of an advocacy intervention to reduce smoking among teenagers

OBJECTIVES: To test whether high school students' participation in advocacy activities related to the advertising, availability, and use of tobacco in their communities would prevent or reduce their own tobacco use. DESIGN: Ten continuation high schools in northern California, randomly assigned to a semester-long program in which students either carried out advocacy activities to counter environmental-level smoking influences in their communities (treatment) or learned about drug and alcohol abuse prevention (control). PARTICIPANTS: Eleventh and 12th grade high school students; 5 (advocacy) treatment and 5 control schools over 4 semesters from 2000 through 2002. MAIN OUTCOME MEASURES: Self-reported smoking defined as nonsmokers (those who had never smoked tobacco or those who were former smokers), light smokers (those who smoked <1 pack per week), or regular smokers (those who smoked >or=1 pack per week), and confirmed by carbon monoxide level readings. The following 3 constructs related to social cognitive theory- perceived incentive value, perceived self-efficacy, and outcome expectancies-were assessed. RESULTS: There was a significant net change from baseline to the end of the semester (after the intervention) between treatment and control schools for students who were regular smokers, but not for students who were nonsmokers or light smokers. Regular smoking decreased 3.8% in treatment schools and increased 1.5% in control schools (P<.001). Regular smoking continued to decrease at 6 months after the intervention in treatment schools, with a total change in prevalence from 25.1% to 20.3%. Involvement in community-advocacy activities and the 3 social constructs-perceived incentive value, perceived self-efficacy, and outcome expectancies-also showed significant net changes between treatment and control schools (all P values <.01). CONCLUSION: Student engagement in community-advocacy activities that addressed environmental influences of cigarette smoking resulted in significant decreases in regular smoking.     

Initiation of the gonadotropin-releasing hormone antagonist ganirelix for in vitro fertilization cycles in which the lead follicle is >14 mm

The initiation of GnRH antagonists when the lead follicle is >14 mm does not adversely affect IVF success rates and leads to a shortened duration of GnRH antagonist administration.     

Controversial ultrasound findings

This article has reviewed a few of the more controversial findings in the field of obstetric ultrasound. For each one evidence-based strategies for the management of affected pregnancies have been suggested, derived from what the authors believe is the best information available. In some cases, this information is very limited, which can make counseling these patients extremely difficult. Some physicians find using specific likelihood ratios helpful in these complex discussions. An example of the relative likelihood ratios for several markers of trisomy 21 is illustrated in Table 10. Although the management of each of the findings discussed in this article is different, a few generalizations can be made. To begin with, the detection of any abnormal finding on ultrasound should prompt an immediate detailed ultrasound evaluation of the fetus by someone experienced in the diagnosis of fetal anomalies. If there is more than one abnormal finding on ultrasound, if the patient is over the age of 35, or if the multiple marker screen is abnormal, an amniocentesis to rule out aneuploidy should be recommended. Of the six ultrasound findings reviewed here, the authors believe that only echogenic bowel as an isolated finding confers a high enough risk of aneuploidy to recommend an amniocentesis in a low-risk patient. The other findings in isolation in a low-risk patient seem to confer only a modest increased risk of aneuploidy, if any, and this risk is certainly less than the risk of unintended loss from amniocentesis.Wherever possible, modifiers of this risk, such as maternal age, history, and first and second multiple marker screening, should be used to define more clearly the true risk of aneuploidy. As obstetric ultrasound moves forward, particularly into the uncharted waters of clinical use of three- and four-dimensional ultrasound, one can expect a whole new crop of ultrasound findings with uncertain clinical significance. Clinicians are well advised to await well-designed studies to determine the clinical significance of these findings before altering clinical care.     

Acceptable, manageable, and tolerable days: patient daily goals for medication management of persistent pain

Although the construct of "a symptom-free day" has been widely applied in asthma and gastric reflux disease, there is no analogous concept in the field of pain management. This study represents the initial development of a "day of acceptable or manageable pain control," a construct which reflects patients' daily strategic use of pain medication in order to allow the accomplishment of desired activities while minimizing side effects. Focus group methodology was used to extract patient-generated themes of "an acceptable day of pain control." Fifty-three outpatients with persistent moderate to severe average pain intensity due to osteoarthritis (n=18), metastatic cancer (n=15), and low back pain (n=20) participated. Participants preferred the term "manageable" or "tolerable" to "acceptable." Thematic analysis revealed components of a manageable/tolerable day of pain control as including: 1) taking the edge off the pain, 2) performing valued activities; 3) relief from dysphoria and irritability; 4) reduced medication side effects; 5) feeling well enough to socialize. Additional cancer-specific themes included relief from fatigue and ability to have a positive day when one's future days were perceived as being limited. The set of themes is presented and their relevance for developing a measure of "a manageable day of pain control" discussed. Study findings identify a novel construct that can inform development of an outcome for evaluating the effectiveness of different pharmacotherapies for pain management.     

Nutritional support in the critically injured

Nutritional support must be an integral part of the management of trauma victims. This article compares the stress response, a maladaptive response, and starvation, an adaptive process, examines the clinical research regarding total parenteral nutrition and total enteral nutrition, provides an evidence-based approach to initiating nutritional support in critically injured patients, and discusses considerations in selecting nutritional formulas.