Associations of Acculturation and Gender with Obesity and Physical Activity among Latinos

Objective: Latinos disproportionately experience overweight/obesity (OWOB) and insufficient physical activity (PA), which are risk factors for numerous health conditions. Whereas numerous studies investigate acculturation as a determinant of OWOB and PA, few have examined acculturation multidimensionally, and none has examined its interaction with gender. Methods: Participants were 140 Latino adults. Primary outcomes were status as OWOB and endorsement of insufficient PA. Acculturation was measured with the Multidimensional Acculturation Scale II. Logistic regression analyses were used to examine the moderating effect of gender on the relationship between each acculturation scale and outcome, controlling for education, nativity, and smoking status. Results: Greater Spanish proficiency was significantly associated with lower odds of insufficient PA. Greater American Cultural Identity was significantly associated with higher odds of OWOB. Women had significantly higher odds of endorsing insufficient PA compared to men. Gender did not moderate the relationship between acculturation and either OWOB or PA. Conclusions: Acculturation is similarly associated with OWOB and insufficient PA for Latino men and women. Cultural identity may need to be considered to target OWOB interventions. Acculturation may be less important, and gender more important, to consider for appropriate targeting of PA interventions.

Associations of At-Risk Drinking, Current Smoking, and Their Co-Occurrence With Primary Care Service Utilization

PURPOSE

Smoking and at-risk drinking are each associated with lower primary care utilization, but the influence of their co-occurrence is not known. The current study compared associations of endorsement of one behavior vs endorsement of both with primary care utilization.

DESIGN

Cross-sectional telephone survey.

SETTING

All United States and Territories.

SUBJECTS

246 801 adults aged 18-64.

MEASURES

The outcome was endorsement of attending a past-year primary care visit. Predictor variables included drinking and smoking status examined individually and combined.

ANALYSIS

Multivariable logistic regressions, adjusted for socio-demographics and number of chronic health conditions.

RESULTS

The odds of attending a past-year primary care visit were 24% lower for persons who drank at risk levels compared to the odds of persons who did not drink and 36% lower for persons who smoked vs those who did not smoke. Among persons who endorsed at least one risk behavior, the odds of attending a past-year primary care visit were 25-35% lower for those who engaged in multiple behaviors compared to the odds of persons who engaged in one behavior.

CONCLUSION

Substance use screening and intervention services in primary care may not be reaching individuals with the greatest need for services. Proactive outreach and identification of primary care utilization barriers are needed, with special consideration of those with co-occurring substance use.

Associations of positive and negative affect on health risk behaviors among Latinos

OBJECTIVE

Negative affect is widely emphasized in behavior modification interventions. However, positive affect is associated with smoking cessation, physical activity, and healthy dietary habits and may be an important treatment target. Few studies have examined the relationship between positive affect and health behaviors among Latinos, who disproportionately experience modifiable health risk behaviors. This study examined the independent associations of positive affect and negative affect on modifiable health risk behaviors among Latino adults.

METHOD

Data came from 432 persons who participated in one of two studies examining determinants of modifiable health risk behaviors among Latino adults. Primary outcomes were current smoking, at-risk drinking, insufficient physical activity, and insufficient fruit and vegetable consumption. Predictors were positive and negative affect as measured by the Positive and Negative Affect Schedule. Associations between positive and negative affect and health risk behaviors were examined using multiple logistic regression.

RESULTS

Positive affect was associated with lower odds of insufficient physical activity and insufficient fruit and vegetable consumption and lower odds of engaging in multiple health risk behaviors. Negative affect was associated with higher odds of at-risk drinking and current smoking.

CONCLUSIONS

Emphasis on increasing positive affect may be warranted for multiple health risk behavior interventions targeting Latinos. Intervention development efforts may also consider prioritizing positive affect for physical activity and dietary interventions, and negative affect for at-drinking and smoking cessation interventions. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The contribution of positive affect and loneliness on readiness and self-efficacy to quit smoking among Spanish-speaking Mexican American smokers

BACKGROUND

The existing research on affective and interpersonal determinants of smoking cessation largely under-represents minority smokers, such as Latinos.

OBJECTIVE

The current study examined associations between affective and interpersonal factors with intermediary smoking cessation variables among Mexican-American smokers (N = 290; 60% male).

METHODS

Measures of positive and negative affect, social support, and loneliness were each examined for associations with measures of motivational readiness to quit smoking, and smoking abstinence self-efficacy. Significant predictors were entered into models simultaneously to examine their unique associations. Covariates included gender, age, and educational attainment.

RESULTS

Negative affect (b = .68, SE b = .14, p < .001) and loneliness (b = .20, SE b = .09, p < .05) were independently associated with motivation. Negative affect (b = .20, SE b = .06, p < .01) and positive affect (b = .34 SE b = .07, p < .001) were independently associated with self-efficacy. In the final models, only negative affect was associated with motivation (b = .68, SE b = .17, p < .001); whereas negative (b = .17, SE b = .06, p < .01) and positive (b = . 32, SE b = .07, p < .001) affect were associated with self-efficacy.

CONCLUSION

Results highlight the importance of resilience factors (e.g., positive affect) among Mexican-American smokers. Cessation interventions regularly target negative affect among smokers; additional focus on positive affect in cessation interventions with this population may be warranted.

Associations of cannabis use frequency and cannabis use disorder with receiving a substance use screen and healthcare professional discussion of substance use

BACKGROUND AND OBJECTIVES

Screening, brief intervention, and referral to treatment (SBIRT) can reduce substance use, but receipt of these services by those who use cannabis frequently and have cannabis use disorder (CUD) remains unexplored. We examined cannabis use frequency and CUD's associations with the odds of receiving a substance use screening and a healthcare professional discussion among those who used healthcare services.

METHODS

Data came from the 2015-2019 National Survey on Drug Use and Health (N = 214,505 aged 18+). Among adults who used cannabis and attended healthcare settings in the past year (N = 36,374), multivariable logistic regression analysis was used to examine associations of cannabis use frequency and CUD with receiving a substance use screen and substance use discussion by a healthcare professional.

RESULTS

Cannabis use frequency was associated with higher odds of receiving a screen (adjusted odds ratio [AOR] = 1.27, 95% confidence interval [CI] = 1.14-1.41 for 300+ days of use) and a discussion among those screened (AOR = 1.83, 95% CI = 1.60-2.09 for 300+ days of use). CUD was not associated with receiving a screen, but it was positively associated with receiving a discussion among those screened (AOR = 1.22, 95% CI = 1.08-1.39). Nonmedical users were less likely to have a discussion among those screened and not screened.

DISCUSSION AND CONCLUSIONS

Findings indicate disparities in screening and discussion of substance use with patients, especially between medical and nonmedical users.

SCIENTIFIC SIGNIFICANCE

Study findings provide novel insight into differences in the reach of SBIRT services among adult cannabis users.

Cannabis use, use frequency, and use disorder in large metropolitan, small metropolitan, and nonmetropolitan areas

BACKGROUND

Despite significant geographical heterogeneity of sociodemographic and clinical characteristics, little is known about potential differences in cannabis use behaviors in U.S. geographic areas. In this study, we examined cannabis use behaviors in large metropolitan, small metropolitan, and nonmetropolitan areas. We focused on interactions between geographic areas and health insurance status and medical cannabis laws (MCL).

METHODS

Data came from the 2015-2018 National Survey on Drug Use and Health (NSDUH; N = 171,766 adults; N = 36,175 cannabis users). Weighted chi-squares tests of independence and multivariable Poisson regression models were used to examine study questions.

RESULTS

Past-year use was highest in large metropolitan areas (16.08 %). Frequent use was highest among nonmetropolitan area users (48.67 %). Uninsured adults had a higher likelihood of past-year use (RRR = 1.21, 95 % CI = 1.14, 1.29) and frequent use (RRR = 1.27, 95 % CI = 1.14, 1.41), but a lower likelihood of cannabis use disorder (RRR = 0.77, 95 % CI = 0.66, 0.89). Uninsured adults in nonmetropolitan areas had a higher likelihood (RRR = 1.62, 95 % CI = 1.39, 1.88) of past-year use than insured nonmetropolitan area adults. MCL state residency was associated with a higher likelihood of frequent use among nonmetropolitan (RRR = 1.39, 95 % CI = 1.11, 1.74) and small metropolitan users (RRR = 1.30, 95 % CI = 1.15, 1.47). Cannabis use disorder likelihood did not vary by geographic area.

CONCLUSIONS

Lack of health insurance and MCL state residency are significant variables affecting cannabis use behaviors in small metropolitan and/or nonmetropolitan areas.

LRIG1 is a pleiotropic androgen receptor-regulated feedback tumor suppressor in prostate cancer

LRIG1 has been reported to be a tumor suppressor in gastrointestinal tract and epidermis. However, little is known about the expression, regulation and biological functions of LRIG1 in prostate cancer (PCa). We find that LRIG1 is overexpressed in PCa, but its expression correlates with better patient survival. Functional studies reveal strong tumor-suppressive functions of LRIG1 in both AR+ and AR- xenograft models, and transgenic expression of LRIG1 inhibits tumor development in Hi-Myc and TRAMP models. LRIG1 also inhibits castration-resistant PCa and exhibits therapeutic efficacy in pre-established tumors. We further show that 1) AR directly transactivates LRIG1 through binding to several AR-binding sites in LRIG1 locus, and 2) LRIG1 dampens ERBB expression in a cell type-dependent manner and inhibits ERBB2-driven tumor growth. Collectively, our study indicates that LRIG1 represents a pleiotropic AR-regulated feedback tumor suppressor that functions to restrict oncogenic signaling from AR, Myc, ERBBs, and, likely, other oncogenic drivers.

Multispecialty retrospective review of the clinical utility of pelvic magnetic resonance imaging in the setting of pelvic pain

Background

Pelvic pain is a common complaint, and management of it is often difficult. We sought to evaluate the utility of magnetic resonance imaging (MRI) in the diagnosis of male pelvic pain. Though MRIs are commonly ordered to evaluate pelvic pain, there are very few studies obtaining the efficacy of pelvic MRI in determining a definitive diagnosis. The primary aim of our study was to evaluate the clinical utility of pelvic MRI for a diagnosis code that included pain.

Methods

After receiving institutional review board approval, a retrospective study was performed of all pelvic MRIs completed at our institution from January 2, 2010 to December 31, 2014. These were further delineated into ordering providers by specialty and urology-specific International Classification of Diseases, Ninth Revision (ICD-9) code diagnoses (male pelvic pain, prostatitis, groin pain, scrotal pain, testicular pain, and penile pain). Clinical utility was defined as positive if MRI findings resulted in a change in management. Subanalysis was performed on patients with an ICD-9 co-diagnosis of previous oncologic concern.

Results

A total of 2,643 pelvic MRIs were ordered at our institution over a 5-year period. Of these, 597 pelvic MRIs (23%) were ordered for a diagnosis code that included pain (hip pain, rectal pain, joint pain, penile pain, scrotal pain, male pelvic pain and orchitis). Total utility for MRIs to find anatomic abnormalities potentially responsible for the present pain was 34% (205/597). When ordered by urologic providers, utility was 23%. Oncologists represented the highest positivity rate at 57%.

Conclusions

Chronic pelvic pain is a multispecialty complaint that is difficult to treat. We were surprised to find the large number of both specialists and generalists invested in the management of pelvic pain. The increasing availability of MRI technology makes it a likely candidate to test for a clinically significant anatomic reason for pain. Though MRI is a test with minimal adverse effect and no increased risk of radiation exposure, the cost on the healthcare system should be offset by a clear clinical utility. We found total utility to be 34% across all ordering providers and an increase in positivity with concern of oncologic disease. Therefore, we would recommend pelvic MRIs in the evaluation of patients with refractory pelvic pain.

Comment on "Critical wind speed at which trees break"

Virot et al. [E. Virot et al., Phys. Rev. E 93, 023001 (2016)10.1103/PhysRevE.93.023001] assert that the critical wind speed at which ⩾50% of all trees in a population break is ≈42 m/s, regardless of tree characteristics. We show that empirical data do not support this assertion, and that the assumptions underlying the theory used by Virot et al. are inconsistent with the biomechanics of trees.

Ligament Mediated Fragmentation of Viscoelastic Liquids

The breakup and atomization of complex fluids can be markedly different than the analogous processes in a simple Newtonian fluid. Atomization of paint, combustion of fuels containing antimisting agents, as well as physiological processes such as sneezing are common examples in which the atomized liquid contains synthetic or biological macromolecules that result in viscoelastic fluid characteristics. Here, we investigate the ligament-mediated fragmentation dynamics of viscoelastic fluids in three different canonical flows. The size distributions measured in each viscoelastic fragmentation process show a systematic broadening from the Newtonian solvent. In each case, the droplet sizes are well described by Gamma distributions which correspond to a fragmentation-coalescence scenario. We use a prototypical axial step strain experiment together with high-speed video imaging to show that this broadening results from the pronounced change in the corrugated shape of viscoelastic ligaments as they separate from the liquid core. These corrugations saturate in amplitude and the measured distributions for viscoelastic liquids in each process are given by a universal probability density function, corresponding to a Gamma distribution with n_{min}=4. The breadth of this size distribution for viscoelastic filaments is shown to be constrained by a geometrical limit which can not be exceeded in ligament-mediated fragmentation phenomena.

Modelling the influence of predicted future climate change on the risk of wind damage within New Zealand's planted forests

Wind is the major abiotic disturbance in New Zealand's planted forests, but little is known about how the risk of wind damage may be affected by future climate change. We linked a mechanistic wind damage model (ForestGALES) to an empirical growth model for radiata pine (Pinus radiata D. Don) and a process-based growth model (cenw) to predict the risk of wind damage under different future emissions scenarios and assumptions about the future wind climate. The cenw model was used to estimate site productivity for constant CO2 concentration at 1990 values and for assumed increases in CO2 concentration from current values to those expected during 2040 and 2090 under the B1 (low), A1B (mid-range) and A2 (high) emission scenarios. Stand development was modelled for different levels of site productivity, contrasting silvicultural regimes and sites across New Zealand. The risk of wind damage was predicted for each regime and emission scenario combination using the ForestGALES model. The sensitivity to changes in the intensity of the future wind climate was also examined. Results showed that increased tree growth rates under the different emissions scenarios had the greatest impact on the risk of wind damage. The increase in risk was greatest for stands growing at high stand density under the A2 emissions scenario with increased CO2 concentration. The increased productivity under this scenario resulted in increased tree height, without a corresponding increase in diameter, leading to more slender trees that were predicted to be at greater risk from wind damage. The risk of wind damage was further increased by the modest increases in the extreme wind climate that are predicted to occur. These results have implications for the development of silvicultural regimes that are resilient to climate change and also indicate that future productivity gains may be offset by greater losses from disturbances.

Tumor-suppressive functions of 15-Lipoxygenase-2 and RB1CC1 in prostate cancer

15-Lipoxygenase-2 (15-LOX2) is a human-specific lipid-peroxidizing enzyme most prominently expressed in epithelial cells of normal human prostate but downregulated or completely lost in>70% of prostate cancer (PCa) cases. Transgenic expression of 15-LOX2 in the mouse prostate surprisingly causes hyperplasia. Here we first provide evidence that 15-LOX2-induced prostatic hyperplasia does not progress to PCa even in p53(+/-) or p53(-/-) background. More important, by generating 15-LOX2; Hi-Myc double transgenic (dTg) mice, we show that 15-LOX2 expression inhibits Myc-induced PCa development, such that in the 3-month- and 6-month-old dTg mice, there is a significant reduction in prostate intraneoplasia (PIN) and PCa prevalent in age-matched Hi-Myc prostates. The dTg prostates show increased cell senescence and expression of several senescence-associated molecules, including p27, phosphorylated Rb, and Rb1cc1. We further show that in HPCa, 15-LOX2 and c-Myc manifest reciprocal protein expression patterns. Moreover, RB1CC1 accumulates in senescing normal human prostate (NHP) cells, and in both NHP and RWPE-1 cells, the 15-LOX2 metabolic products 15(S)-HPETE and 15(S)-HETE induce RB1CC1. We finally show that unlike 15-LOX2, RB1CC1 is not lost but rather frequently overexpressed in PCa samples. RB1CC1 knockdown in PC3 cells enhances clonal growth in vitro and tumor growth in vivo. Together, our present studies provide evidence for tumor-suppressive functions for both 15-LOX2 and RB1CC1.

Application of the fractional Fourier transform to the design of LCOS based optical interconnects and fiber switches

It is shown that reflective liquid crystal on silicon (LCOS) spatial light modulator (SLM) based interconnects or fiber switches that use defocus to reduce crosstalk can be evaluated and optimized using a fractional Fourier transform if certain optical symmetry conditions are met. Theoretically the maximum allowable linear hologram phase error compared to a Fourier switch is increased by a factor of six before the target crosstalk for telecom applications of -40 dB is exceeded. A Gerchberg-Saxton algorithm incorporating a fractional Fourier transform modified for use with a reflective LCOS SLM is used to optimize multi-casting holograms in a prototype telecom switch. Experiments are in close agreement to predicted performance.

The effects of spinal cord injury and exercise on bone mass: a literature review

INTRODUCTION

Bone loss is a common and often debilitating condition that accompanies spinal cord injury. Because bone loss after spinal cord injury is multifactorial, it can be difficult to assess and treat. This process becomes even more complex as secondary conditions associated with aging are introduced.

PURPOSE

There are two purposes of this literature review. The first is to summarize information concerning the mechanisms of bone loss and osteoporosis after spinal cord injury. The second is to summarize existing data concerning the effects of exercise on bone loss after spinal cord injury.

METHOD

Literature was reviewed concerning the bone loss process and the non-pharmacological treatment options for ameliorating bone loss after spinal cord injury.

RESULTS

(Part One) Osteoporosis is universal in persons with chronic complete spinal cord injury, which increases the risk of bone fracture. Bone loss after spinal cord injury is both sublesional and regional with the greatest areas of bone demineralization being in the sublesional trabecular laden areas of the distal and proximal epiphyses of the femur and tibia. (Part Two) While passive weight bearing of paralyzed lower extremities appears to be ineffective, stressing the bones through muscular contractions initiated by electrical stimulation (FES) have yielded positive results in some cases. The intensity, frequency, and duration of stress to the bones appear to be important determinants of improved bone parameters. Although further quantification of these components is needed, some generalized guidelines can be deduced from completed research. Intensities showing positive results have been loads of one to one and a half times body weight for FES exercise or having participants FES cycle at their highest power output. Safety precautions must be used to decrease risk of bone fracture. Generally, the frequency is effective with three or more weekly exercise sessions. Studies of duration suggest that several months to one or more years of FES are necessary.

DISCUSSION

In order to promote healthy and independent aging in patients with spinal cord injury, it is important to understand the processes, consequences and effective treatments involved with bone loss.

Use of wavefront encoding in optical interconnects and fiber switches for cross talk mitigation

A technique of cross talk mitigation developed for liquid crystal on silicon spatial light modulator based optical interconnects and fiber switches is demonstrated. By purposefully introducing an appropriate aberration into the system, it is possible to reduce the worst-case cross talk by over 10 dB compared to conventional Fourier-transform-based designs. Tests at a wavelength of 674 nm validate this approach, and show that there is no noticeable reduction in diffraction efficiency. A 27% spot increase in beam diameter is observed, which is predicted to reduce at longer datacom and telecom wavelengths.

Modulation of actin mechanics by caldesmon and tropomyosin

The ability of cells to sense and respond to physiological forces relies on the actin cytoskeleton, a dynamic structure that can directly convert forces into biochemical signals. Because of the association of muscle actin-binding proteins (ABPs) may affect F-actin and hence cytoskeleton mechanics, we investigated the effects of several ABPs on the mechanical properties of the actin filaments. The structural interactions between ABPs and helical actin filaments can vary between interstrand interactions that bridge azimuthally adjacent actin monomers between filament strands (i.e. by molecular stapling as proposed for caldesmon) or, intrastrand interactions that reinforce axially adjacent actin monomers along strands (i.e. as in the interaction of tropomyosin with actin). Here, we analyzed thermally driven fluctuations in actin's shape to measure the flexural rigidity of actin filaments with different ABPs bound. We show that the binding of phalloidin increases the persistence length of actin by 1.9-fold. Similarly, the intrastrand reinforcement by smooth and skeletal muscle tropomyosins increases the persistence length 1.5- and 2- fold respectively. We also show that the interstrand crosslinking by the C-terminal actin-binding fragment of caldesmon, H32K, increases persistence length by 1.6-fold. While still remaining bound to actin, phosphorylation of H32K by ERK abolishes the molecular staple (Foster et al. 2004. J Biol Chem 279;53387-53394) and reduces filament rigidity to that of actin with no ABPs bound. Lastly, we show that the effect of binding both smooth muscle tropomyosin and H32K is not additive. The combination of structural and mechanical studies on ABP-actin interactions will help provide information about the biophysical mechanism of force transduction in cells.

Simulating the dynamic behavior of Douglas-fir trees under applied loads by the finite element method

The finite element method of structural analysis was used to model the dynamic behavior of three 20-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees subjected to applied loading. Detailed measurements of stem and branch geometry were made for each tree, enabling the first-order branches of each tree to be represented as individual cantilever beams attached to the stem. Three values for branch modulus of elasticity (E) were assumed: 4, 5 and 6 GPa. For two trees with relatively large crown masses (175 and 250 kg), significantly improved estimates of natural frequency were obtained when the branches were modeled as separate cantilever beams rather than as a series of discrete masses attached to the stem. Closest agreement with the results from field sway tests was found when branch E was 4 GPa. Oscillations of individual branches contributed to the damping of tree oscillations--a phenomenon known as structural damping--with the contribution increasing as branch E decreased. When branch E was 4 GPa, the phase difference between the oscillation of the stem and that of some branches was almost 180 degrees. We applied a series of forces separately to the stem and branches of each tree and determined the mechanical transfer function for each loading case. These transfer functions were similar to the theoretical transfer function for a damped harmonic oscillator, but showed a smaller tree response at higher loading frequencies, particularly when branch E was 4 GPa. Branch structural properties, particularly modulus of elasticity, appear to be important in defining overall tree behavior under applied loading.

Hypertrophic and dilated cardiomyopathy mutations differentially affect the molecular force generation of mouse α-cardiac myosin in the laser trap assay

Point mutations in cardiac myosin, the heart's molecular motor, produce distinct clinical phenotypes: hypertrophic (HCM) and dilated (DCM) cardiomyopathy. Do mutations alter myosin's molecular mechanics in a manner that is predictive of the clinical outcome? We have directly characterized the maximal force-generating capacity (Fmax) of two HCM (R403Q, R453C) and two DCM (S532P, F764L) mutant myosins isolated from homozygous mouse models using a novel load-clamped laser trap assay. Fmaxwas 50% (R403Q) and 80% (R453C) greater for the HCM mutants compared with the wild type, whereas Fmaxwas severely depressed for one of the DCM mutants (65% S532P). Although Fmaxwas normal for the F764L DCM mutant, its actin-activated ATPase activity and actin filament velocity ( Vactin) in a motility assay were significantly reduced (Schmitt JP, Debold EP, Ahmad F, Armstrong A, Frederico A, Conner DA, Mende U, Lohse MJ, Warshaw D, Seidman CE, Seidman JG. Proc Natl Acad Sci USA 103: 14525–14530, 2006.). These Fmaxdata combined with previous Vactinmeasurements suggest that HCM and DCM result from alterations to one or more of myosin's fundamental mechanical properties, with HCM-causing mutations leading to enhanced but DCM-causing mutations leading to depressed function. These mutation-specific changes in mechanical properties must initiate distinct signaling cascades that ultimately lead to the disparate phenotypic responses observed in HCM and DCM.

Modelling environmental variation in Young's modulus for Pinus radiata and implications for determination of critical buckling height

BACKGROUND AND AIMS

Although density-specific stiffness, E/rho, (where E is Young's modulus and rho is wood density) is often assumed constant by the elastic similarity model, and in determination of critical buckling height (H(crit)), few studies have tested this assumption within species. Here this assumption is tested for Pinus radiata growing across an environmental gradient, and theory is combined with data to develop a model of Young's modulus.

METHODS

Analyses use an extensive series of environmental plots covering the range of climatic and edaphic conditions over which P. radiata is grown in New Zealand. Reduced major axis regression was used to determine scaling exponents between log-log plots of H(crit) vs. groundline diameter (D), and E/rho vs. D. Path analysis was used to identify significant direct and indirect (through stem slenderness) edaphic and climatic influences on E.

KEY RESULTS

Density-specific stiffness exhibited 3-fold variation. As E/rho scaled positively with D, the exponent of 0.95 between H(crit) and D exceeded the assumed value of 0.67 under constant E/rho. The final path analysis model included mean air temperature in early autumn (T(aut)) and slenderness as significant (P < 0.05) positive direct influences on E. Tree leaf area index and T(aut) were indirectly associated with E through their significant (P < 0.05) positive direct relationship with stem slenderness. Young's modulus was most sensitive to T(aut), followed by stem slenderness then leaf area index, and the final model explained 76 % of the variance in E.

CONCLUSIONS

The findings suggest that within species E/rho variation may influence H(crit) and the scaling exponent between D and H(crit) so important in assumptions regarding allometric relationships. The model presented may provide a useful means of determining variation in E, E/rho and H(crit) across environmental gradients.

Gas in stems: abundance and potential consequences for tree biomechanics

Secondary xylem of woody plants has a large volumetric proportion of gas occupying spaces that would otherwise be filled with water. We examined whether these gas-filled voids have a mechanical role by either decreasing the fresh mass the tree must support (by replacing some of the water with gas) or by providing inexpensive filler to increase stem diameter (thereby increasing the second moment of area at the expense of the modulus of elasticity and modulus of rupture). Calculations from published data show that temperate softwood species (n = 26) average 18 and 50% gas by volume for sapwood and heartwood, respectively; temperate hardwood species (n = 31) average 26% gas by volume in both the sapwood and heartwood; and tropical species (n = 52) with mixed sapwood and heartwood have 18% gas by volume. In this paper, we develop equations to show how gas affects the mechanical behavior of tree stems, and describe model results to show how gas affects mechanical stability, based on mass and stem diameters for six 34-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. For the same applied load, modeled stems in which the gas space was filled with water differed in their surface stresses by < 2% from modeled stems in the native state (partially gas-filled), indicating no practical benefit from a reduction in stem mass due to gas. A second modeling scenario compared the native state to stems in which gas was removed and stem diameters decreased (and material properties adjusted to concur with the increased wood density) to conserve mass. Removal of the gas-filled voids resulted in up to 41% higher surface stress for the same applied load, caused by a decrease in the second moment of area greater than the increase in modulus of elasticity. Trees with gas removed had higher modulus of rupture, but could withstand up to 14% lower maximum wind forces than trees in their native state, suggesting a biomechanical role for the gas if the model assumptions are valid. The gas content may, however, have evolved in response to pressures unrelated to biomechanics. We discuss some of its potential effects on sapwood physiology.

Myosin V exhibits a high duty cycle and large unitary displacement

Myosin V is a double-headed unconventional myosin that has been implicated in organelle transport. To perform this role, myosin V may have a high duty cycle. To test this hypothesis and understand the properties of this molecule at the molecular level, we used the laser trap and in vitro motility assay to characterize the mechanics of heavy meromyosin-like fragments of myosin V (M5(HMM)) expressed in the Baculovirus system. The relationship between actin filament velocity and the number of interacting M5(HMM) molecules indicates a duty cycle of > or =50%. This high duty cycle would allow actin filament translocation and thus organelle transport by a few M5(HMM) molecules. Single molecule displacement data showed predominantly single step events of 20 nm and an occasional second step to 37 nm. The 20-nm unitary step represents the myosin V working stroke and is independent of the mode of M5(HMM) attachment to the motility surface or light chain content. The large M5(HMM) working stroke is consistent with the myosin V neck acting as a mechanical lever. The second step is characterized by an increased displacement variance, suggesting a model for how the two heads of myosin V function in processive motion.

The value of diffusion-weighted imaging for prediction of lasting deficit in acute stroke: an analysis of 134 patients with acute neurologic deficits

Acute stroke is one of the three major causes of death and disability in the United States. Now that new, and possibly effective therapy is becoming available, accurate, rapid diagnosis is important to provide timely treatment, while avoiding the risk of complications from unnecessary intervention. Our objective was to test the hypothesis that use of echo-planar (EPI) diffusion-weighted imaging (DWI) is more accurate than conventional T2 weighted MRI in predicting progression to stroke in patients with acute ischemic neurologic deficits. We studied 134 patients presenting with acute neurologic deficits to a community hospital emergency room with both conventional MRI and DWI within 72 h of the onset of the acute deficit. We found DWI significantly more sensitive to permanent neurologic deficit at discharge (sensitivity 0.81) than conventional MRI (sensitivity 0.41). When available, DWI should be considered for routine use in patients being imaged for acute stroke.

Role of the elastic protein projectin in stretch activation and work output of Drosophila flight muscles

We examine how the stretch activation response of the Drosophila indirect flight muscles (IFM) is affected by the projectin mutation bentDominant. IFM from flies heterozygous for this mutation (bentD/+) produce approximately 85% full length projectin and approximately 15% truncated projectin lacking the kinase domain and more C-terminal sequences. Passive stiffness and power output of mutant fibers is similar to that of wild-type (+/+) fibers, but the amplitude of the stretch activation response (delayed tension rise) was significantly reduced. Measurement of actomyosin kinetics by sinusoidal analysis revealed that the apparent rate constant of the delayed tension rise (2 pi b) increased in proportion to the decrease in amplitude, accounting for the near wild-type levels of power output and nearly normal flight ability. These results suggest that projectin plays a crucial role in stretch activation, possibly through its protein kinase activity, by modulating crossbridge recruitment and kinetics.

Expression of c-kit (CD117) in benign and malignant human endometrial epithelium

BACKGROUND

The proto-oncogene c-kit encodes a tyrosine kinase receptor (CD117) with a molecular weight of 145 kd. Previous studies, predominantly utilizing immunohistochemistry, have led to contradictory findings regarding the expression of CD117 in the endometrium. To help resolve this issue, we analyzed a series of benign and malignant endometrial tissues using both immunohistochemistry and Western blot analysis.

OBJECTIVE

To examine the expression of CD117 in benign and malignant human endometrial tissues.

METHODS

The expression of CD117 in 35 benign endometrial tissues (7 hyperplastic, 14 proliferative, 14 secretory) and 10 endometrioid carcinomas was investigated by immunohistochemistry (clone K45 monoclonal antibody). Immunoprecipitation (clone K69 monoclonal antibody) followed by Western blotting (clone K45 monoclonal antibody and clone 1.D9.3D6 monoclonal antibody) was performed to confirm CD117 expression.

RESULTS

Fifty-seven percent of the hyperplasias, 93% of proliferative endometria, and 79% of secretory endometria immunostained positively for CD117. In benign endometria, epithelial staining tended to be more intense in the hyperplastic and proliferative endometria as compared to the secretory endometria, whereas endometrial stromal cells were not immunoreactive. Of the 10 frozen endometrial tissues analyzed by immunohistochemistry, 4 of 9 endometrioid carcinomas and a single case of an endometrioid polyp developing in association with a carcinoma expressed CD117. Immunoprecipitation followed by Western blot analysis confirmed expression of full-length CD117 in an endometrial polyp and carcinoma, and revealed a correlation between levels of immunoprecipitated CD117 and immunohistochemical staining intensity.

CONCLUSIONS

Benign and malignant endometrial tissues express CD117. Our data suggest (a) a possible relationship between estrogen and CD117 expression in benign endometrium and (b) potential involvement of this growth factor receptor in endometrial carcinogenesis.

High-resolution diffusion imaging using phase-corrected segmented echo-planar imaging

Diffusion magnetic resonance imaging (MRI) was performed with a high-resolution segmented echo-planar imaging technique, which provided images with substantially less susceptibility artifacts than images obtained with single-shot echo-planar imaging (EPI). Diffusion imaging performed with any multishot pulse sequence is inherently sensitive to motion artifacts and in order to reduce motion artifacts, the presented method utilizes navigator echo phase corrections, performed after a one-dimensional Fourier transform along the frequency-encoding direction. Navigator echo phases were fitted to a straight line prior to phase correction to avoid errors from internal motion. In vivo imaging was performed using electro cardiographic (ECG) triggering. Apparent diffusion coefficient (ADC) maps were calculated on a pixel-by-pixel basis using up to seven diffusion sensitivities, ranging from b = 0 to 1129 x 10(6) s/m(2).

The effect of removing the N-terminal extension of the Drosophila myosin regulatory light chain upon flight ability and the contractile dynamics of indirect flight muscle

The Drosophila myosin regulatory light chain (DMLC2) is homologous to MLC2s of vertebrate organisms, except for the presence of a unique 46-amino acid N-terminal extension. To study the role of the DMLC2 N-terminal extension in Drosophila flight muscle, we constructed a truncated form of the Dmlc2 gene lacking amino acids 2-46 (Dmlc2(Delta2-46)). The mutant gene was expressed in vivo, with no wild-type Dmlc2 gene expression, via P-element-mediated germline transformation. Expression of the truncated DMLC2 rescues the recessive lethality and dominant flightless phenotype of the Dmlc2 null, with no discernible effect on indirect flight muscle (IFM) sarcomere assembly. Homozygous Dmlc2(Delta2-46) flies have reduced IFM dynamic stiffness and elastic modulus at the frequency of maximum power output. The viscous modulus, a measure of the fly's ability to perform oscillatory work, was not significantly affected in Dmlc2(Delta2-46) IFM. In vivo flight performance measurements of Dmlc2(Delta2-46) flies using a visual closed-loop flight arena show deficits in maximum metabolic power (P(*)(CO(2))), mechanical power (P(*)(mech)), and flight force. However, mutant flies were capable of generating flight force levels comparable to body weight, thus enabling them to fly, albeit with diminished performance. The reduction in elastic modulus in Dmlc2(Delta2-46) skinned fibers is consistent with the N-terminal extension being a link between the thick and thin filaments that is parallel to the cross-bridges. Removal of this parallel link causes an unfavorable shift in the resonant properties of the flight system, thus leading to attenuated flight performance.

The Drosophila projectin mutant, bentD, has reduced stretch activation and altered indirect flight muscle kinetics

Projectin is a ca. 900 kDa protein that is a member of the titin protein superfamily. In skeletal muscle titins are involved in the longitudinal reinforcement of the sarcomere by connecting the Z-band to the M-line. In insect indirect flight muscle (IFM), projectin is believed to form the connecting filaments that link the Z-band to the thick filaments and is responsible for the high relaxed stiffness found in this muscle type. The Drosophila mutant bentD (btD) has been shown to have a breakpoint close to the carboxy-terminal kinase domain of the projectin sequence. Homozygotes for btD are embryonic lethal but heterozygotes (btD/+) are viable. Here we show that btD/+ flies have normal flight ability and a slightly elevated wing beat frequency (btD/+ 223+/-13 Hz; +/+ 203+/-5 Hz, mean +/- SD; P < 0.01). Electron microscopy of btD/+ IFM show normal ultrastructure but skinned fiber mechanics show reduced stretch activation and oscillatory work. Although btD/+ IFM power output was at wild-type levels, maximum power was achieved at a higher frequency of applied length perturbation (btD/+ 151+/-6 Hz; +/+ 102+/-14 Hz; P < 0.01). Results were interpreted in the context of a viscoelastic model of the sarcomere and indicate altered cross-bridge kinetics of the power-producing step. These results show that the btD mutation reduces oscillatory work in a way consistent with the proposed role of the connecting filaments in the stretch activation response of IFM.

Phosphorylation-dependent power output of transgenic flies: an integrated study

We examine how the structure and function of indirect flight muscle (IFM) and the entire flight system of Drosophila melanogaster are affected by phosphorylation of the myosin regulatory light chain (MLC2). This integrated study uses site-directed mutagenesis to examine the relationship between removal of the myosin light chain kinase (MLCK) phosphorylation site, in vivo function of the flight system (flight tests, wing kinematics, metabolism, power output), isolated IFM fiber mechanics, MLC2 isoform pattern, and sarcomeric ultrastructure. The MLC2 mutants exhibit graded impairment of flight ability that correlates with a reduction in both IFM and flight system power output and a reduction in the constitutive level of MLC2 phosphorylation. The MLC2 mutants have wild-type IFM sarcomere and cross-bridge structures, ruling out obvious changes in the ultrastructure as the cause of the reduced performance. We describe a viscoelastic model of cross-bridge dynamics based on sinusoidal length perturbation analysis (Nyquist plots) of skinned IFM fibers. The sinusoidal analysis suggests the high power output of Drosophila IFM required for flight results from a phosphorylation-dependent recruitment of power-generating cross-bridges rather than a change in kinetics of the power generating step. The reduction in cross-bridge number appears to affect the way mutant flies generate flight forces of sufficient magnitude to keep them airborne. In two MLC2 mutant strains that exhibit a reduced IFM power output, flies appear to compensate by lowering wingbeat frequency and by elevating wingstroke amplitude (and presumably muscle strain). This behavioral alteration is not seen in another mutant strain in which the power output and estimated number of recruited cross-bridges is similar to that of wild type.

Nasal cartilage grafts: more than a decade of experience

From 1985 to 1995, a total of 311 patients underwent nasoplasties. During this time period, the number of patients receiving grafts increased from 94 percent in 1985-1989 to 100 percent in 1993-1995. The donor grafts averaged 72 percent nasal cartilage, 10 percent conchal cartilage, 9 percent fascia, and 9 percent rib allograft. Graft recipient sites averaged 41 percent in the tip, 31 percent in the dorsum, 17 percent in the columella, and 3 percent in the region of the lower lateral cartilage; 8 percent were spreader grafts. During this time frame, tip grafting increased from 34 percent in 1985-1989 to 54 percent in 1993-1995. Reoperation for complications decreased from 17 percent in 1985-1989 to 2 percent in 1993-1995. During the time span examined, the use of rib allografts declined, the use of autologous cartilage increased, the use of onlay tip grafts increased, and the incidence of reoperations declined. Early in the series, 80 percent of the malplaced tips were shield type grafts. With the use of the onlay tip graft, the complication of a malpositioned tip has been substantially diminished. The increased use of crushed cartilage has resulted in improvement in results and patient satisfaction, as it serves to camouflage slight irregularities in the tip and dorsum of the nose.

Correction for distortion of echo-planar images used to calculate the apparent diffusion coefficient

An algorithm for correcting the distortions that occur in diffusion-weighted echo-planar images due to the strong diffusion-sensitizing gradients is presented. The dominant distortions may be considered to be only changes of scale coupled with a shear and linear translation in the phase-encoding direction. It is then possible to correct for them by using an algorithm in which each line of the image in the phase-encoding direction is considered in turn, with only one parameter (the scale) to be found by searching.

Endoscopic transaxillary submuscular augmentation mammaplasty with textured saline breast implants

The utility of the endoscope was realized in a retrospective analysis of 92 consecutive patients undergoing augmentation mammaplasty with saline-filled textured implants. The transaxillary submuscular approach was used. All patients received preoperative antibiotics and instillation of methylprednisolone into the saline fill, with inflation to manufacturer-recommended levels. complications included seven implant deflations (3.8%), eight implant malpositions (4.3%), and one capsular contracture (0.6%). Of the eight malpositions, six were corrected using the endoscopic technique without removal of the implant and with early manipulation of the implant within the pocket. We conclude that endoscopic control in augmentation mammaplasty is beneficial in secondary operative procedures and we speculate that the endoscope will lessen the rate of implant malposition observed in this study.

Infant sleep position and the sudden infant death syndrome. A survey of pediatric recommendations

A questionnaire survey was conducted to assess the impact of the April 1992 American Academy of Pediatrics Task Force Statement, "Infant Positioning and SIDS," on the routine advice provided by pediatricians in Minnesota to families with newborn infants regarding sleep practices, including sleep position. There was a trend toward more discussion between all pediatric practice groups and families regarding infant sleep practices following the AAP Sleep Position Statement (P < 0.001-0.003). Prone sleep recommendations ranged from 9.2% for newborn infants to 21.4% for infants 6 months of age. Recommendations for the supine or lateral sleep positions predominated at all infant ages. Pediatricians in private practice were more likely to identify the AAP Statement as establishing a medicolegal standard (P < 0.05). We conclude that the 1992 AAP Statement has had a significant impact on the routine advice provided to families regarding infant sleep practices, including infant sleep position.

Solid state phosphorus-31 magnetic resonance imaging of bone mineral

Chemically selective solid state phosphorus-31 nuclear magnetic resonance (NMR) imaging of the mineral phase of bone and synthetic calcium phosphate models for bone mineral is demonstrated with microscopy-scale (about 5 mm field of view) apparatus at 6.0 T magnetic field strength. Pixel-by-pixel linear combination of image data from multiple radio frequency (RF) pulse sequences, chosen to develop contrast between chemical constituents of interest in the mineral, generates derived images showing the distribution of individual constituents. The technique combines the noninvasive character of magnetic resonance imaging (MRI) with the ability of solid state NMR spectroscopy to characterize subtle chemical variations in bone mineral, as well as to measure the amount of mineral. These methods are, in principle, extensible to larger dimensional scales suitable for live animal subjects or human limbs.

Elderly residents: perceptions of nurses' comforting touch

1. Elderly nursing home residents often feel unwanted or unloved because of a lack of physical contact with others or their caregivers' inability to communicate love and belonging. 2. In a study of 25 elderly nursing home residents, it was found that those who were subjected to comforting touch by their nurses perceived an increased feeling of affection and immediacy. 3. The conscious and intentional use of comforting touch by nurses and caregivers to elderly nursing home residents should be encouraged because of its beneficial effect of conveying love and belonging.

Steps in the evolution of extracranial time-of-flight MR angiography

Magnetic resonance (MR) angiography is not a set technique but is constantly evolving. This article illustrates changes in image quality in extracranial MR angiography that have been achieved over the past few years by the introduction of several technical developments. Images from patients examined at intervals of 12 months or more demonstrate the improvements in image quality that have resulted from these technical changes. These include bandwidth optimization for operation at 1.0 T and changes in flip angle section thickness, repetition time, and echo time. Improved image quality was assessed with objective measures of contrast-to-noise and signal-to-noise ratios. The cases illustrated show the use of MR angiography to evaluate the portal or systemic veins in patients being evaluated for liver transplantation, venous occlusion, and other venous disease. Improvements in image quality are subjectively apparent and emphasize the importance of keeping pace with technical improvements in MR angiography.

Antioxidant status of dairy cows supplemented prepartum with vitamin E and selenium

Possible relationships among dietary antioxidants, oxidative status, and placental retention were investigated in periparturient dairy cows. During 6 wk prepartum, 16 cows each were given daily by capsule 1000 IU of vitamin E, 3 mg of Se, both vitamin E and Se, or neither (control). alpha-Tocopherol in serum and fast-acting antioxidants in plasma increased, but, in red blood cells, thiobarbituric acid-reactive substances decreased during the last 6 wk before parturition in cows given vitamin E. These measurements were unaffected by supplementation of Se. Cows that had retained placenta > or = 12 h had lower fast-acting antioxidants in plasma and glutathione peroxidase in red blood cells up to 2 wk before calving than did cows that shed fetal membranes in < 12 h. Results suggest that inadequate dietary antioxidants may increase oxidative stress, production of lipid peroxides, and incidence of retained fetal membranes in dairy cows.

Hypertension secondary to chlorpropamide with amelioration by changing to insulin

A retrospective analysis of the records of 22 type II diabetics whose treatment had been changed from insulin to chlorpropamide was performed to investigate the relative effects of insulin and chlorpropamide on blood pressure. Although diastolic BP index was not significantly different between the treatments, systolic BP index was significantly higher on chlorpropamide than on insulin (141 +/- 3 v 135 +/- 3 mm Hg, P = .02). In 10 patients in whom insulin was reinstituted, systolic BP fell significantly (P < .005), suggesting that in type II diabetics chlorpropamide exerts a relative hypertensive effect in comparison to insulin.

Measurement of visceral blood flow with magnetic resonance imaging

With the increasing application of magnetic resonance imaging (MRI) and MR angiography in parenchymal liver disease, methods are becoming more widely available for noninvasive measurement of visceral blood flow. Amplitude-based (time-of-flight) and phase-based techniques have proved effective for measurement of portal blood flow, and phase-sensitive methods are applicable to arterial flow measurements. Because respiratory motion degrades the quality of examinations in the abdomen, it is desirable to use methods that can generate flow information in a breath-hold period. Although substantial technical difficulties persist for quantitative arterial flow measurements in the abdomen, the technical requirements for venous flow are less stringent, and important clinical information can be derived using straightforward techniques. The authors describe the principles of flow measurement using time-of-flight and phase methods in visceral arteries and veins, and discuss their practical implementation. Clinical applications are discussed, based on the experience of the authors and others working in the field.

The transverse carpal ligament. An important component of the digital flexor pulley system

The effect of release of the transverse carpal ligament on the mechanics of the flexor tendons was investigated with use of a fresh-frozen cadaver model. A 25 per cent increase in the amount of excursion of the tendons that was consumed by motion of the wrist was demonstrated for the digitorum profundus tendons after transection of the transverse carpal ligament, and a 20 per cent increase was noted for the digitorum superficialis tendons (p < 0.001). These values represent 5.4 +/- 1.2 and 5.5 +/- 1.3 millimeters of bow-stringing for each group of tendons.

Real-time NMR beam-directed velocity mapping. V-mode NMR

BACKGROUND

Currently available noninvasive techniques for measuring blood flow velocities are constrained by limited view orientations (Doppler ultrasound) or limited time resolution (magnetic resonance imaging, MRI). We describe an MRI technique for measuring flow velocities in real time at arbitrary orientations within a cylindrical volume or "beam": V-mode nuclear magnetic resonance (NMR).

METHODS AND RESULTS

The technique was implemented on a standard 1.5-T clinical NMR imager with no special hardware and was tested on phantoms and human volunteers. The beam can be fired at rates up to 60 times per second, allowing measurements on a time scale that is appropriate for ungated cardiac studies. In phantoms, steady flow velocities were measured with the beam aligned along the direction of flow, and the measured velocities correlated well with the actual velocities (r > 0.99). The radial distribution of velocities in phantoms under constant flow conditions was also determined. In humans, flow of blood in the descending aortas of normal and aortic insufficiency subjects was measured. Distinctive backflow of blood because of aortic insufficiency was readily apparent.

CONCLUSIONS

The V-mode NMR technique is capable of acquiring clinically relevant real-time blood flow information from any desired angle of view with no attenuation at bone or air-tissue interfaces.

Neonatal compartment syndrome

Two cases of forearm compartment syndrome in neonates are presented. The compartment syndrome may be initiated before actual delivery and may appear in an advanced stage. In both children good clinical results were achieved when standard guidelines for managing compartment syndrome and established Volkmann's contracture were applied. Although uncommon, compartment syndrome should be considered in the differential diagnosis of the neonate who is unable to move an extremity.

Rapid NMR cardiography with a half-echo M-mode method

A real-time NMR cardiac profiling pulse sequence has been developed that incorporates two-dimensional (2D) selective excitation and a half-echo readout. The time resolution has been improved by a factor of two relative to the previous flow-compensated, full-echo version. The technique produces a 2D plot of "beam"-axis position versus time, analogous to M-mode echocardiography. In human subjects, details of valve leaflet motion, intracardiac flow, wall motion, and wall thickening may be observed along optimal lines of sight selected interactively. The pulse sequence uses a low-tip-angle 2D selective-excitation pulse derived from a spiral k-space trajectory to excite a narrow cylinder of magnetization, followed by a half-echo readout gradient oriented along the axis of the cylinder. One-dimensional Fourier transformation of the acquired signal results in a magnetization profile along the length of the cylinder, or beam. The pulse sequence is effectively flow compensated without any additional gradient lobes, because the rapid oscillation in the gradient wave forms of the 2D excitation pulse produces relatively small net gradient moments, and the shortened readout gradient has minimal first-order moment relative to center echo. The signal from moving blood can alternatively be velocity encoded by the addition of bipolar gradients along any of the three axes, producing Doppler-like traces of intracardiac blood flow.

Radial shortening for Kienböck disease

The cases of twenty-nine consecutive patients (thirty wrists) who had radial shortening for the treatment of stages I through IIIB Kienböck disease were reviewed to assess the results of this procedure. Thirteen patients (45 per cent) had a history of trauma, and all thirty wrists had a negative ulnar variance (average, 2.8 millimeters) on radiographs. All wrists were re-examined after an average follow-up of 3.8 years (minimum, two years). At that time, the pain had decreased in 87 per cent of the wrists. Extension of the wrist had improved an average of 32 per cent; flexion, 27 per cent; radial deviation, 30 per cent; ulnar deviation, 41 per cent; and grip strength on the affected side, 49 per cent. Analysis of the radiographs by computer digitization showed no significant changes in the amount of collapse of the lunate at the latest follow-up. In two wrists, there were complications at follow-up (excessive shortening of the radius and non-union of the radial osteotomy). Radial shortening is an effective treatment for Kienböck disease in wrists that do not have degenerative changes in adjacent carpal joints. Pain, range of motion, and strength can be expected to improve, but the radiographic appearance of the lunate changes little, if any.

Progress in efforts to prevent the spread of HIV infection among youth

The Human Immunodeficiency Virus (HIV) that causes AIDS will continue to threaten public health for years to come. Despite some popular misperceptions, adolescents are at risk of infection. Twenty percent of persons reported with AIDS have been ages 20 through 29. Given the long incubation period between HIV infection and AIDS, some of these young adults probably were infected while they were teenagers. Young people must develop the skills they will need to avoid HIV infection and other related health problems. In 1987, the Centers for Disease Control (CDC) launched a national program to help schools and other agencies that serve youth across the nation provide effective health education to prevent the spread of HIV. CDC supports and works closely with national health and education organizations, State and local education agencies, colleges and universities, and local health departments to establish HIV prevention policies and programs, training and demonstration centers, information development and dissemination activities. The impact of these efforts are assessed through applied surveillance and evaluation research. Through this system, CDC is attempting to institutionalize the means for continuously providing educational programs that will be effective in preventing HIV infection and other important health problems.