Capstan-like mechanism in hyaluronan-phospholipid systems.

Functionality of articular cartilage results from complex interactions between its molecular components. Among many biomolecules, two are of prime importance for lubrication: hyaluronic acid (HA) and phospholipids (PL). The purpose of this study is to discuss a mechanism of interaction between these two components and how their synergies contribute to nanobiolubrication of articular cartilage. Preliminary molecular dynamics simulations have been performed to investigate these interactions by adopting a capstan-like mechanism of action. By applying a constant pulling force to both ends of a HA molecule, wrapped around a PL micelle, we viewed the rotation of the PL micelle. The simulations were performed upon two physicochemical constraints: force- and solvent-dependency. The results show the efficiency of rotation from intermolecular bond creation and annihilation. We found a direct relation between the available surface of the micelle and the magnitude of the force, which varies significantly through the unwinding. The movement of the attached molecules is characterized by a slide-to-roll relation, which is affected by the viscosity of the surrounding medium. As a consequence, two solvents were studied for specific force conditions and the molecular dynamics simulation exhibited double the slide-to-roll coefficient for the viscous solvent as compared to its low-viscosity limit.

Pet dogs and child physical activity: the role of child-dog attachment.

BACKGROUND: Dog ownership has been associated with increased physical activity in children which in turn may mitigate childhood obesity. OBJECTIVE: To measure the association between child-dog attachment and child physical activity and screen time. METHODS: Cross-sectional study including 370 children (ages 4-10) who had pet dogs in the home. Parents completed the DartScreen, a web-based screener, before a well-child visit. Screener domains included child body mass index (BMI), physical activity, screen time and dog-related questions. The Companion Animal Bonding Scale (CABS) was used to measure child attachment to the dog. Clinic nurses weighed and measured the children. Associations between CABS, BMI z-score, screen time and physical activity were estimated. RESULTS: CABS was strongly associated with time spent being active with the dog (F = 22.81, p < 0.0001), but not with BMI z-score or screen time. CONCLUSIONS: A higher level of child attachment to a pet dog is associated with increased child physical activity.

[Anti-aging medicine, a science-based, essential medicine]. / La médecine anti-âge, une médecine scientifique, indispensable.

Anti-aging medicine is booming. It enters more and more in the programs of universities. Its hormone and nutritional tests and therapies rely on numerous scientific studies, including double-blind placebo-controlled randomized studies. Its methods are often innovative to obtain more information or benefits with greater safety. The fundamental purpose of anti-aging medicine is to optimize health and the quality of life, and through this, make the physical appearance more youthful. Well-chosen and well-dosed these treatments should not increase the risk of age-related diseases such as cancer and cardiovascular diseases, but on the contrary decrease it by the preventive aspect of the treatments. Opponents to anti-aging medicine fail in collecting valid scientific arguments. Their insistence on maintaining a society of elderly people looking and feeling as elderly people rather than actively participating in searching for ways to attenuate aging is harmful to all who follow them, to themselves in the first place.

[On Two Opposing (Bio)surfaces as Comprehended in Terms of an Extension of the Coulomb-Amontons Law of Friction, with Its Virtual Usefulness for Biotribology in Nanoscale].

An extension of the Coulomb-Amontons law is proposed in terms of an interaction-detail involving renormalization (simplified) n-th level scheme. The coefficient of friction is obtained in a general exponential (nonlinear) form, characteristic of virtually infinite (or, many body) level of the interaction map. Yet, its application for a hydration repulsion bilayered system, prone to facilitated lubrication, is taken as linearly confined, albeit with an inclusion of a decisive repelling force/pressure factor. Some perspectives toward related systems, fairly outside biotribological issues, have been also addressed.

Controlling protein crystal growth rate by means of temperature.

We have proposed a model to analyze the growth kinetics of lysozyme crystals/aggregates under non-isothermal conditions. The model was formulated through an analysis of the entropy production of the growth process which was obtained by taking into account the explicit dependence of the free energy on the temperature. We found that the growth process is coupled with temperature variations, resulting in a novel Soret-type effect. We identified the surface entropy of the crystal/aggregate as a decisive ingredient controlling the behavior of the average growth rate as a function of temperature. The behavior of the Gibbs free energy as a function of temperature is also analyzed. The agreement between theory and experiments is very good in the range of temperatures considered.

On the spherical prototype of a complex dissipative late-stage formation seen in terms of least action Vojta-Natanson principle.

The spherical prototype of a crystalline and/or disorderly formation may help in understanding the final stages of many complex biomolecular arrangements. These stages are important for both naturally organized simple biosystems, such as protein (or, other amphiphilic) aggregates in vivo, as well as certain their artificial counterparts, mimicking either in vitro or in silico their structure-property principal relationship. For our particular one-seed based realization of a protein crystal/aggregate late-stage nucleus grown from nearby fluctuating environment, it turns out that the (osmotic-type) pressure could be, due to local inhomogeneities, and their dynamics shown up in the double layer tightly surrounding the growing object, still an appreciably detectable quantity. This is due to the fact that a special-type generalized thermodynamic (Vojta-Natanson) momentum, subjected to the nucleus' surface, is manifested interchangeably, whereas the total energy of the solution in the double layer could not be such within the stationary regime explored. It is plausible since the double layer width, related to the object's surface, contributes ultimately, while based on the so-defined momentum's changes, to the pressure within this narrow flickering zone, while leaving the total energy fairly unchanged. From the hydrodynamic point of view, the system behaves quite trivially, since the circumventing flow should rather be of laminar, thus not-with-matter supplying, character.

Thermokinetic approach of single particles and clusters involving anomalous diffusion under viscoelastic response.

We present a thermokinetic description of anomalous diffusion of single particles and clusters in a viscoelastic medium in terms of a non-Markovian diffusion equation involving memory functions. The scaling behavior of these functions is analyzed by considering hydrodynamics and cluster-size space random walk arguments. We explain experimental results on diffusion of Brownian particles in the cytoskeleton, in cluster-cluster aggregation, and in a suspension of micelles.

Bronchodilators for bronchiolitis.

BACKGROUND: Bronchiolitis is an acute, highly infectious lower respiratory tract infection. Bronchodilators are commonly used in the management of bronchiolitis in North America but not in the United Kingdom. OBJECTIVES: The objective of this review was to assess the effects of bronchodilators on clinical outcomes in infants with acute bronchiolitis. SEARCH STRATEGY: In this updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) and the Database of Abstracts of Reviews of Effects (DARE) (The Cochrane Library, Issue 1, 2006), MEDLINE (1966 to October 2005), EMBASE (2003 to September 2005) and the reference lists of articles. The files of one author (AG) were also reviewed. SELECTION CRITERIA: Randomized controlled trials (RCTs) comparing bronchodilators (other than epinephrine) with placebo in the treatment of bronchiolitis. DATA COLLECTION AND ANALYSIS: For this updated review, one author assessed trial quality and extracted data. Unpublished data were requested from study authors when necessary. MAIN RESULTS: Twenty-two clinical trials with 1428 infants with bronchiolitis were included in this review. In eight trials, with 468 infants, there was no improvement in clinical score for 43% of those treated with bronchodilators compared to 57% of those treated with placebo (odds ratio (OR) for no improvement 0.45, 95% confidence interval (CI) 0.15 to 1.29). There was a statistically significant but clinically modest improvement in the overall average clinical score (standardized mean difference (SMD) -0.48, 95% CI -0.62 to -0.33). However there was no statistically significant improvement in oxygenation overall (weighted mean difference (WMD) -0.57, 95% CI -1.17 to 0.03). Subgroup analyses showed a slightly greater effect size in outpatient studies, where there were shorter follow up durations, than in inpatient studies for both oximetry (outpatients WMD -0.84, 95% CI -1.59 to -0.10 versus inpatients WMD -0.25, 95% CI -1.18 to 0.67) and average clinical score (outpatients SMD -0.68, 95% CI -0.87 to -0.49 versus inpatients SMD -0.23, 95% CI -0.44 to -0.01). Bronchodilator recipients showed no improvement in the rate of hospital admission after treatment as outpatients (18% versus 26%, OR 0.70, 95% CI 0.36 to 1.35) or duration of hospitalization for inpatients (WMD 0.02, 95% CI -0.32 to 0.36). The inclusion of studies that enrolled infants with recurrent wheezing may have biased the results in favor of bronchodilators. AUTHORS' CONCLUSIONS: Bronchodilators produce small short-term improvements in clinical scores. This small benefit must be weighed against the costs and adverse effects of these agents.

Changes in health care providers' knowledge, attitudes, beliefs, and behaviors regarding domestic violence, following a multifaceted intervention.

PURPOSE: To improve domestic violence (DV) identification, management, and referral in a not-for-profit rural health network, training for health care professionals was implemented using a train-the-trainer approach, two one-hour training sessions, and dissemination of a clinical protocol. The multifaceted approach also involved modifications of emergency department medical records, distribution of office enablers, and a local public health campaign. The authors measured the effectiveness of this campaign. METHODS: After implementation of a multifaceted training and public awareness campaign, a questionnaire designed by the Centers for Disease Control to measure knowledge, attitudes, beliefs, and intended behaviors (KABB) of health care providers relative to DV was administered to 380 health care professionals in the fall of 1997, with a follow-up survey completed after the intervention in the fall of 1999. RESULTS: The response rates for the pre- and post-intervention surveys were 67% (n = 380) and 56% (n = 273), respectively. Two scales were correlated in the base-line survey: self-efficacy (related to DV response) and familiarity with referral resources. Reporting of victim identification in the preceding year increased from 36% to 39%. Those with training were more likely to have identified a victim within the year (OR = 2.86; 95% CI, 1.73-4.74). Among the 232 respondents with complete data, multiple analysis of variance demonstrated statistically significant overall improvement across all scales. Nine of the 13 KABB scales revealed significant increases from pre- to posttest and included: screening, workplace resources, making referrals, provider self-efficacy, victim autonomy, victim understanding, legal requirements, staff preparation, and too busy/can't help. CONCLUSION: A comprehensive training program for health care providers can increase their self-efficacy in responding to DV victims.

Ruptured appendicitis among children as an indicator of access to care.

OBJECTIVE: To determine factors associated with ruptured appendicitis among children, using administrative databases. Insurance-related differences in the risk of ruptured appendix among adults in California have previously been described (Braveman, Schaaf, Egerter, et al. 1994). DATA SOURCES/STUDY SETTING: State of Maryland Medicaid claims data for children < or = 18 years of age from 1989 to 1993 and hospital discharge data for children < or = 19 years of age from 1989 to 1994 were analyzed. STUDY DESIGN: Administrative data analysis pre- and post-implementation of a Medicaid managed care program called Maryland Access to Care. DATA COLLECTION/EXTRACTION METHODS: Medicaid claims and hospital discharge ICD-9-CM codes were used to define hospitalization for ruptured and nonruptured appendicitis. Linear regression was used to model trends. Logistic regression was used to model the probability of ruptured appendicitis. PRINCIPAL FINDINGS: Among the 374 Medicaid inpatient claims for appendicitis, 37 percent were for ruptured appendicitis. Among the 5,141 hospital discharges for appendicitis, 30 percent were for ruptured appendicitis. Using Medicaid claims data, the probability of ruptured appendicitis was inversely related to age (OR = 0.86, 95% CI 0.81-0.91), white race (OR = 0.35, 95% CI 0.17-0.71) and preventive care visits (OR = 0.19, 95% CI 0.05-0.77). Using hospital discharge data, age (OR = 0.91, 95% CI 0.90-0.93) and female gender (OR = 0.87, 95% CI 0.77-0.99) were significant covariates. Insurance-related covariates were not significant in multivariate models addressing the probability of ruptured appendicitis. CONCLUSIONS: During a period of rapid managed care growth, insurance type was not associated with an increased risk of ruptured appendicitis among children in this geographic area. Age, female gender, and the number of preventive care visits are inversely related to the risk of ruptured appendix among children. The protective effect of preventive care visits suggests that a primary care relationship facilitates access to care, thus reducing delay in the management of appendicitis.

Impact of a rural domestic violence prevention campaign.

Domestic violence is a prevalent health problem that in rural areas is further complicated by limited services, social isolation and the lack of privacy. Little is known about the impact of public health education on awareness, attitudes and behavior of the general public regarding domestic violence. This study sought to measure change in societal attitudes and behavioral intention in response to a seven-month public health education campaign targeting domestic violence in a rural county. From October 1998 to April 1999, the campaign used radio advertisements, posters, mailings to libraries and clergy, printed media articles, printed advertisements and health facility modifications. A random-digit-dialing telephone survey was used to evaluate attitudinal and behavioral changes in the intervention and comparison counties before and after the campaign. The response rates for the pre- (n =378) and postcampaign (n=633) surveys were 73 percent and 65 percent, respectively. Statistically significant increases in slogan and advertising recognition occurred in the intervention county (P=0.03), particularly among men recalling the campaign slogan (P=0.006). In a vignette regarding actions to be taken if the neighbor next door was abusing a partner, significant increases occurred in the intervention county in the percentage of respondents who thought that most people would talk to the victim (P=0.04), consult with friends (P=0.002) or talk to a doctor (P=0.004). Domestic violence agency hotline calls in the intervention county doubled following the campaign. Local public health education campaigns in a rural setting may be a valuable adjunct to national efforts, especially in reaching men.

Insights from a large rural population laboratory. Health census '89 and '99.

PURPOSE: Data are limited on health status behaviors and use of health services for rural residents. Yet rural areas now have higher rates of chronic diseases, such as coronary heart disease, than urban areas.METHODS: A population laboratory (Health Census) was established in rural Central NY (Otsego County) to study these variables in this population. HC '89 was a door-to-door enumeration of all permanent households in the country. In 1989, 44,500 adults in 18,000 households provided data on individual health screenings, cancer and cardiovascular risk factors, health behaviors, chronic disease, access to care, preventive services use, health insurance and emergency department utilization. Data collection for HC '99 will identify 10-year trends; it also includes baseline data for children. Also, households in six surrounding rural counties (N = 10,000) were sampled; cost benefits of different survey methods were assessed. Questions about perceived health status, and special health and pediatric preventive care needs were included. After 10 years of social change, many limitations of traditional survey methods became apparent; much more varied and frequent types of follow-up were needed to achieve adequate response rates.RESULTS: The HC '89 final response rate was 86%. There were significant socioeconomic gradients in use of preventive services (blood pressure screening, rectal exams, mammograms and Pap smears). Adults without health insurance or Medicaid had much lower utilization rates of screening tests and higher rates of cigarette smoking and obesity. Several community intervention programs were implemented as a result of HC '89. HC '99 provides additional analyses to examine change in preventive service use, self-reported chronic disease, and health services use; it will likely verify the persistence of socioeconomic gradients. Response rates are similar to '89, but achieved only with more intensive reinforcement.CONCLUSIONS: HC '89 confirmed a lag in positive health indices in rural populations in Central NY. Both newer methodologies now needed and results of HC '99 will serve as guides for smaller rural counties to develop affordable local health surveys and plan intervention strategies.

Bronchodilators for bronchiolitis.

OBJECTIVES: Bronchiolitis is an acute, highly communicable lower respiratory tract infection. Bronchodilators are commonly used in the management of bronchiolitis in North America, but not in the United Kingdom. The objective of this review was to assess the effects of bronchodilators for bronchiolitis. SEARCH STRATEGY: We searched MEDLINE, EMBASE, Reference Update, reference lists of articles, and the files of two of the authors up to June 1998. SELECTION CRITERIA: Randomised trials comparing bronchodilators with placebo in the treatment of bronchiolitis. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Unpublished data were requested from authors when necessary. MAIN RESULTS: In eight trials with 394 children, 46% demonstrated an improved clinical score with bronchodilators compared to 75% with placebo (odds ratio for no improvement 0.29, 95% confidence interval 0.19 to 0.45). However, the inclusion of studies that enrolled people with recurrent wheezes may have biased these results in favour of bronchodilators. Bronchodilator recipients did not show improvement in measures of oxygenation, the rate of hospitalisation (18% versus 26%, odds ratio 0.70, 95% confidence interval 0.36 to 1.35) or duration of hospitalisation (weighted mean difference 0.12, 95% confidence interval -0.3 to 0.5). REVIEWER'S CONCLUSIONS: Bronchodilators produce modest short-term improvement in clinical scores. This small benefit must be weighed against the costs of these agents.

Echocardiographic assessment of right atrial thrombus related to the implanted port device in patient receiving chemotherapy for non-Hodgkin's lymphoma.

The case of a potentially life-threatening complication related to the use of implanted port device in a 8 year old Non-Hodgkin's Lymphoma patient receiving chemotherapy is described. The device was inserted in early 1997 and used repeatedly for chemotherapy without any complications. In late 1997 during routine screening for cardiac left ventricular function before re-introduction of chemotherapy, an abnormal 1.43 x 1.53 cm mass, consistent with a non-mobile thrombus was found in the right atrium. The initial thrombolytic therapy with recombinant tissue plasmin activator (rt-PA) infused by a central venous catheter was combined with daily echocardiographic examination in order to assess both the timing and mode of thrombus resolution. After 8 days systemic fibrinolytic therapy was discontinued as major hemorrhage from venipuncture sites occurred and the clot dissolution was not obtained. Patient underwent right atriotomy utilizing cardiopulmonary bypass and subsequent surgical thrombus removal was successful. The study evaluated the contribution of two-dimensional echocardiography (2D) in the follow-up of vascuport and other central venous catheter (CVC) location and early diagnosis of related complications such as thrombi. The authors consider that pulmonary flow analyzed with Doppler echocardiography as a reliable, suitable and non-invasive method to evaluate increased pulmonary artery pressure in children with right atrial thrombi and probability of pulmonary microembolism or embolism. As the incidence of right atrial thrombi is highly associated with the catheter tip position in the right atrium, in contrast to their positioning in the superior vena cava or in its junction with the right atrium, the authors recommend that special attention and effort should be given to placing of the catheter tip in the superior vena cava or in its junction with the right atrium avoiding the right atrium during the implantation procedure. The surgical right atrium thrombus removal in patients with no clot dissolution despite systemic thrombolytic treatment underscores the importance of surgical therapy in treating this life-threatening complication of indwelling catheters.

Children's mental health: recommendations for research, practice and policy.

A recent study documented a large increase in prescriptions of stimulants and antidepressants among preschoolers, and has prompted public and professional concern about the effects of mood-altering drugs on young children. In response, the White House announced a broad initiative on children's mental health, including more government money for research, new labels on drugs for pediatric use, educational materials for parents, and a fall White House conference. To place these events in their larger context, this Issue Brief summarizes the findings of the Children's Mental Health Alliance Project, which conducted a multidisciplinary consensus conference in November 1998 followed by a year-long dialogue with clinicians, researchers, and families.

Polymorphic phase transitions in systems evolving in a two-dimensional discrete space.

Polymorphic phase transitions in systems evolving in a two-dimensional discrete space have been studied. The driving force of the transitions appears to be a difference between two main energetic contributions: one, related to the thermal activation of the process, and another, being of quantum nature. The former (high temperature limit) is naturally assigned to the expansion (melting) part of the transition, while the latter (low temperature limit) has much in common with the contraction (solidification) part. Between the two main physical states distinguished, there exists a certain state, corresponding to a discontinuity point (pole) in the morphological phase diagram, represented by the well-known Bose-Einstein (Planck) formula, in which the system blows up. This point is related to an expected situation in which the contour of the object under investigation stands for the Brownian or purely diffusional path, with the fractal dimension dw=2, and the situation can be interpreted as some emergence of an intermediate "tetratic" phase. This, in turn, recalls a certain analogy to the equilibrium (order-disorder) phase transition of Kosterlitz-Thouless type, characteristic of, e.g., rough vs rigid interfaces in a two-dimensional space, with some disappearance of interface correlation length at dw=2. Otherwise, the contours of the objects are equivalent to fractional Brownian paths either in superlinear or "turbulent" (dw<2; the expansion case), or sublinear, viz., anomalously slow (dw>2; the contraction case) regimes, respectively. It is hoped that the description offered will serve to reflect properly the main subtleties of the dynamics of the polymorphic transitions in complex "soft-matter" systems, like formation of lipid mesomorphs or diffusional patterns, with nonzero line tension effect.

Population-based study of the adequacy of well-child care services: a rural county's report card.

OBJECTIVE: To determine the adequacy of well-child care services using a population-based study. DESIGN: The medical records of all county providers and the immunization records at the local health department were reviewed. A county birth cohort, identified using electronic birth certificates, was compared with those who migrated into the area (hereafter, in-migrants). SETTING: All primary care sites (private, network, etc) in a rural county. PATIENTS: Two-year-old children born between May 31, 1993, and May 30, 1994. MAIN OUTCOME MEASURES: Immunization rates and preventive screenings. RESULTS: A total of 674 medical records were reviewed. Of these, 377 (56%) belonged to a county birth cohort and 297 (44%) were in-migrants. Medical records of 64% of the birth cohort were reviewed. Among all 2-year-olds, 80% received 4 doses of diphtheria and tetanus toxoids and pertussis vaccine; 89%, 3 doses of Haemophilus influenzae type b (Hib); 75%, 4 doses of Hib; 77%, 3 doses of hepatitis B vaccine; 85%, measles-mumps-rubella vaccine; 85%, 3 doses of oral poliovirus vaccine; 17%, varicella live virus vaccine (Varivax). The 4:3:1 rate was 75% at age 2 years. Sixty-eight percent had had 1 hematocrit, 74% had 1 lead screening test, and 43% had 2 lead screening tests. A total of 64% had had 6 well-child visits and 30% had had 9. The mean number of weights and heights measured was 4.8 and 4.5, respectively, at age 1 year and 7.3 and 6.8, respectively, at age 2 years. The birth cohort had notably higher rates of documented immunization and preventive screening than in-migrants. CONCLUSIONS: This study demonstrated immunization coverage at or below the national average, and well-child care service provisions below American Academy of Pediatrics standards at a county level. This study enabled individual primary care sites to assess their well-child care provision and provided a useful baseline for targeting the improvement of well-child care services in the county.