Multiple events case-control study in a prospective cohort to identify systemic, cellular, and molecular biomarkers of obesity-induced accelerated aging in 30-years-olds: the ObAGE study protocol

Background

Aging is characterized by a progressive loss of capacities linked to fundamental alterations/damage in multiple cellular and molecular pathways. It is the most significant risk factor for all non-communicable diseases (NCDs). Another contributing factor to the rise in NCDs is obesity. It has been suggested that obesity not only accelerates the onset of metabolic imbalances but also decreases lifespan and impacts cellular and molecular processes in a manner similar to aging. Obesity might accelerate the pace of aging. Guided by a lifecourse approach, we will explore how exposure to obesity in critical developmental stages disrupt homeostatic resilience mechanisms that preserve physiological integrity, inducing an early expression of aging phenotypes. Also, we will determine whether exposure to early psychosocial adversity influences vulnerability to obesity as a risk factor for accelerated aging.

Methods

Multiple events case–control study embedded in a prospective cohort of Chileans at 30-31y, 50% females, of low- to-middle socioeconomic status, who participated in nutrition research since birth. At 23y, 25% had obesity and cardiometabolic risk was high. We will use a multi-layer approach including: anthropometric assessment; DXA scan for body composition; abdominal ultrasound of the liver; stool samples collection and sequencing of the ribosomal RNA 16S gene to characterize the gut microbiome; determination of age-related pro-inflammatory cytokynes and anti-inflammatory miokynes. For the first time in Chile, we will address age-related epigenetic changes using the Horvath´s epigenetic clock. In a subset we will conduct a controlled physical challenge to characterize physical resilience (autophagy).

Discussion

ObAGE is in an excellent position to: approach aging as a process whose expression involves multiple factors from the early stages of a person's life; understand how longitudinal changes in health trajectories impact the biological mechanisms of aging; identify potential resilience mechanisms that help prevent unhealthy aging. Because SLS participants are still young, our research setting combined with advanced scientific techniques may identify individuals or groups at risk of early onset health issues. Results from ObAGE may pave the way to address the contribution of obesity to aging through lifespan from cells to systems and might be instrumental to developing interventions to improve health span in the Chilean population.

Trial registration

The proposed study does not consider any health care intervention on human participants.

Eating in the Absence of Hunger and Obesity Among Adolescents in Santiago, Chile

In reports among mostly, US, white, preschool and young school-age children eating in the absence of hunger (EAH) has been positively related to adiposity, with some support for a sex-specific relationship. There is considerable interest in EAH and obesity in populations at risk for obesity-like populations of countries that have undergone rapid development. We assessed adolescents (n = 679) after an overnight fast with anthropometry and an EAH paradigm beginning with an ad lib pre-load meal. Participants reported satisfaction and perceived ability to eat more food, and then proceeded to a room with freely available snacks where they were permitted to eat ad lib for 20 min. Adolescents were 16.8 years old, 52% male, and 14% with obesity. Median preload meal kcal consumption was 602 (IQR 474-746). Additional calories were consumed at the EAH snack by 47.6%. Among those who ate snack, 155 additional calories were consumed (IQR 78-283). Adolescents with obesity had 0.61 (95% CI 0.37-0.99) reduced odds of eating at the EAH snack adolescents without obesity. Adolescents with obesity were also less likely to eat above the median total calories compared to adolescents without obesity (OR = 0.59, 95% CI 0.36-0.96). A sex by obesity interaction term was not significant in any model. Obesity was related to eating behavior in our sample of Chilean adolescents, however not in the direction we hypothesized. Adolescents with obesity were less likely to eat additional calories in the EAH paradigm and ate fewer total calories compared to adolescents without obesity.

Ferritin levels throughout childhood and metabolic syndrome in adolescent stage

BACKGROUND AND AIM

Increased ferritin levels have been widely associated with cardiovascular risk in adults. Whether ferritin levels and their changes during childhood are related to metabolic syndrome (MetS) at adolescence is unknown. We aimed to evaluate these associations using levels of ferritin at 5, 10 and 16 years and their linear increases and patterns of sustained increased levels across childhood.

METHODS AND RESULTS

There were four samples evaluated according to non-missing values for study variables at each stage (5 years: 562; 10 years: 381; and 16 years: 567 children; non-missing values at any stage: 379). MetS risk was evaluated as a continuous Z score. Patterns of sustained increased ferritin (highest tertile) and slope of the change of ferritin per year across the follow-up were calculated. Ferritin levels in the highest versus lowest tertile at five and 16 years were significantly positively associated with MetS risk Z score at adolescence in boys and these associations were unaffected by adjustment for covariates. Having high, compared to low/moderate ferritin level at 2 or more time periods between 5 and 16 years was related to higher Mets Z-score in boys only [e.g. 5-10 years adjusted-beta (95 %CI):0.26 (0.05-0.48),P < 0.05]. In girls, ferritin Z score at 10 and 16 years was positively and independently associated with HOMA-IR Z score. In girls, the slope of ferritin per year in the highest tertile was positively associated with MetS risk Z-score [adjusted-beta (95 %CI):0.21 (0.05-0.38),P < 0.05].

CONCLUSIONS

Ferritin levels throughout childhood are positively related to cardiometabolic risk in adolescence, with associations varying by sex.

Heparin Effect on Bone Density

In order to provide estimates of the risks of symptomatic osteoporosis and reduced bone density in premenopausal women treated with long-term (greater than 1 month) heparin therapy, we evaluated a cohort of 61 consecutive premenopausal women previously treated with long-term heparin (cases) and a group of controls matched for age, parity and duration between the last pregnancy and evaluation. All patients underwent dual photon absorptiometry of the lumbar spine and single photon absorptiometry of the wrist and most cases underwent plain lateral radiography of the thoracolumbar spine in order to exclude silent fractures. Although none of the cases suffered symptomatic fractures (0 of 61, 95% confidence intervals 0.0 to 5.9%), there was a significantly greater proportion of cases than controls with bone density below our pre-defined levels. The long-term implications of our findings are uncertain but because it is possible that the reduction in bone density predisposes women to fractures, this potential risk should be considered when treating women with long-term heparin.

Low muscle mass is associated with cardiometabolic risk regardless of nutritional status in adolescents: A cross-sectional study in a Chilean birth cohort

BACKGROUND

Increased cardiometabolic risk (CMR) is documented in obese and non-obese adolescents with low muscular fitness. However, the association of low muscle mass (LMM) with CMR, independent of weight status, has not been examined. We analyzed the relationship of LMM with CMR in adolescents, regardless of their weight status.

MATERIALS AND METHODS

Observational study in 660 adolescents. BMI, waist circumference (WC), arterial blood pressures (ABP) were measured. Total fat mass (TFM), total lean tissue (TLT), and appendicular skeletal muscle mass (ASM) were estimated (DXA). Fasting lipid profile, glucose, and insulin were measured. HOMA-IR was estimated. Metabolic Syndrome (MetS) was diagnosed (AHA/NHLBI/IDF). ROC analysis was performed to find the optimal cutoffs of TLT percentage for MetS diagnosis. Values below these cutoffs defined LMM. ANCOVA examined the association of LMM with selected cardiometabolic biomarkers.

RESULTS

In both sexes, TLT showed better sensitivity and specificity than ASM for MetS diagnosis. In males and females, TLT of 66.1% and 56.3%, respectively, were the optimal cutoff for MetS diagnosis. In the sample, 17.3% of males and 23.7% of females had LMM. In both sexes, adolescents with LMM had significantly higher values of WC, ABP, TG, TC/HDL, HOMA-IR, and MetS z-score than non-LMM participants. Adolescents with LMM, regardless nutritional status, had significantly increased values of MetS z-score, ABP, TG, TC/HDL-chol, and HOMA-IR than non-obese non-LMM adolescents. Adolescents having both obesity and LMM had the unhealthiest CMR profile.

CONCLUSION

In adolescents, LMM was associated with higher CMR, regardless of nutritional status. In obese adolescents, LMM increased obesity-associated CMR.

Breastfeeding as the sole source of milk for 6 months and adolescent bone mineral density

Little is known regarding the relationship between early life factors and bone mineral density (BMD). We found a positive association between breastfeeding for at least 6 months, without formula supplementation, and whole body adolescent BMD z-score.

INTRODUCTION

The aim of the study is to assess the role of breastfeeding BF on adolescent bone mineral density (BMD) in a cohort prospectively followed since infancy.

METHODS

We studied 679 participants from an infancy iron deficiency anemia preventive trial in Santiago, Chile, followed to adolescence. Breast and bottle feeding were ascertained weekly from 4 to 12 months. At 16 years, whole body BMD was assessed by DEXA. Using linear regression, we evaluated associations between BF duration and BF as the sole source of milk and adolescent BMD z-score, adjusting for possible infancy, adolescent, and background confounders.

RESULTS

Mean birth weight and length were 3.5 (0.3) kg and 50.7 (1.6) cm. For at least 6 months, BF was the sole source of milk for 26.3% and with supplementation for 36.7%. For 37%, BF was provided for less than 6 months. Mean 16-year BMD z-score was 0.25 (1.0). Covariates included male sex, birth length, and gestational age. BF as the sole source of milk ≥6 months, compared to BF < 6 months, was associated with higher adolescent BMD z-score adjusting for covariates (β = 0.29, p < 0.05). Mixed BF was not significantly related to adolescent BMD z-score (β = 0.06, p = 0.47). For every 30 days of BF as the sole source of milk, adolescent BMD z-score increased by 0.03 (p = 0.01).

CONCLUSION

BF without formula supplementation for at least 6 months was associated with higher adolescent BMD z-score and a suggestive trend in the same direction for BMD suggests that exclusivity and duration of BF may play a role in adolescent bone health.

Healthy Chilean Adolescents with HOMA-IR ≥ 2.6 Have Increased Cardiometabolic Risk: Association with Genetic, Biological, and Environmental Factors

OBJECTIVE

To determine the optimal cutoff of the homeostasis model assessment-insulin resistance (HOMA-IR) for diagnosis of the metabolic syndrome (MetS) in adolescents and examine whether insulin resistance (IR), determined by this method, was related to genetic, biological, and environmental factors.

METHODS

In 667 adolescents (16.8 ± 0.3 y), BMI, waist circumference, glucose, insulin, adiponectin, diet, and physical activity were measured. Fat and fat-free mass were assessed by dual-energy X-ray absorptiometry. Family history of type 2 diabetes (FHDM) was reported. We determined the optimal cutoff of HOMA-IR to diagnose MetS (IDF criteria) using ROC analysis. IR was defined as HOMA-IR values above the cutoff. We tested the influence of genetic, biological, and environmental factors on IR using logistic regression analyses.

RESULTS

Of the participants, 16% were obese and 9.4 % met criteria for MetS. The optimal cutoff for MetS diagnosis was a HOMA-IR value of 2.6. Based on this value, 16.3% of participants had IR. Adolescents with IR had a significantly higher prevalence of obesity, abdominal obesity, fasting hyperglycemia, and MetS compared to those who were not IR. FHDM, sarcopenia, obesity, and low adiponectin significantly increased the risk of IR.

CONCLUSIONS

In adolescents, HOMA-IR ≥ 2.6 was associated with greater cardiometabolic risk.

Melanocortin-4 receptor gene variants in Chilean families: association with childhood obesity and eating behavior

OBJECTIVE

To screen for mutations in the coding region of the melanocortin-4 receptor (MC4R) gene and to assess the association between the rs17782313 variant near MC4R with childhood obesity and eating behavior.

SUBJECTS AND METHODS

A cross-sectional sample of 221 obese Chilean children and 268 parents were incorporated in the study to assemble 134 case-parent trios. We performed direct sequencing of the MC4R coding region while the rs17782313 variant was genotyped by a Taqman assay. Eating behavior scores were calculated using the Child Eating Behavior and Three Factor Eating Questionnaires adapted for Chilean families.

RESULTS

A low frequency of genetic variation in the coding region of MC4R was found in Chilean obese children (Thr150Ile mutation and polymorphisms Ile251Leu and Val103Ile). The rs17782313 variant is possibly associated with satiety responsiveness (P = 0.01) and enjoyment of food scores (P = 0.03).

CONCLUSION

The rs17782313 variant may influence eating behavior in obese children.

The guinea-pig tracheal potential difference as an in vivo model for the study of epithelial sodium channel function in the airways

BACKGROUND AND PURPOSE

The epithelial sodium channel (ENaC) is a key regulator of airway mucosal hydration and mucus clearance. Negative regulation of airway ENaC function is predicted to be of clinical benefit in the cystic fibrosis lung. The aim of this study was to develop a small animal model to enable the direct assessment of airway ENaC function in vivo.

EXPERIMENTAL APPROACH

Tracheal potential difference (TPD) was utilized as a measure of airway epithelial ion transport in the guinea-pig. ENaC activity in the trachea was established with a dose-response assessment to a panel of well-characterized direct and indirect pharmacological modulators of ENaC function, delivered by intra-tracheal (i.t.) instillation.

KEY RESULTS

The TPD in anaesthetized guinea-pigs was attenuated by the direct ENaC blockers: amiloride, benzamil and CF552 with ED(50) values of 16, 14 and 0.2 microg kg(-1) (i.t.), respectively. 5-(N-Ethyl-N-isopropyl) amiloride, a structurally related compound but devoid of activity on ENaC, was without effect on the TPD. Intra-tracheal dosing of the Kunitz-type serine protease inhibitors aprotinin and placental bikunin, which have previously been demonstrated to inhibit proteolytic activation of ENaC, likewise potently attenuated TPD in guinea-pigs, whereas alpha(1)-antitrypsin and soya bean trypsin inhibitor were without effect.

CONCLUSIONS AND IMPLICATIONS

The pharmacological sensitivity of the TPD to amiloride analogues and also to serine protease inhibitors are both consistent with that of ENaC activity in the guinea-pig trachea. The guinea-pig TPD therefore represents a suitable in vivo model of human airway epithelial ion transport.

Effect of glycemic index on whole-body substrate oxidation in obese women

BACKGROUND

Glycemic index is hypothesized to determine fuel partitioning through serum plasma insulin modifications induced by dietary carbohydrates, thereby modulating fat accretion or oxidation.

OBJECTIVE

To assess the glycemic effects on postprandial fuel oxidation and blood response.

DESIGN

In all, 12 obese women were fed on a randomized crossover design with two test meals (breakfast+lunch). High- or low-glycemic meals were provided on separate days. Energy intake on high-glycemic meal was 7758+/-148 kJ and for low-glycemic meal was 7806+/-179 kJ. Carbohydrates supplied were 273+/-5 and 275+/-6 g, respectively. Macronutrient distribution was 55% carbohydrates, 30% fat and 15% protein. Fuel oxidation was measured continuously in a respiratory chamber for 10 h. Serum glucose, free fatty acids (FFA), insulin and glucagon samples were taken for 5 h after breakfast.

RESULTS

Glucose AUC changed significantly in response to different glycemic breakfast. Low- vs high-glycemic breakfast was 211+/-84 and 379+/-164 mmol/l (P<0.05). Similarly, insulin changed from 94+/-37 and 170+/-87 nmol/l (P<0.05), respectively. The rate of increment for serum glucose and insulin reached by the high- vs low-glycemic meal was 1.8 times more with the high-glycemic breakfast. Serum FFA were similarly suppressed by both meal types by 3 h after meal intake, but then raised significantly more with the low-glycemic meal by the fourth and fifth hour (P<0.05). Plasma glucagon did not show a significant variation with glycemic index. Carbohydrate and fat oxidation was not modified by glycemic meal characteristics, being virtually the same for low- vs high-glycemic comparisons in the 5 h following breakfast and lunch (P=NS).

CONCLUSION

This study demonstrates that dietary glycemic characteristics were unable to modify fuel partitioning in sedentary obese women.

The utilisation of engineered invert traps in the management of near bed solids in sewer networks

Large existing sewers are considerable assets which wastewater utilities will require to operate for the foreseeable future to maintain health and the quality of life in cities. Despite their existence for more than a century there is surprisingly little guidance available to manage these systems to minimise problems associated with in-sewer solids. A joint study has been undertaken in the UK, to refine and utilise new knowledge gained from field data, laboratory results and Computational Fluid Dynamics (CFD) simulations to devise cost beneficial engineering tools for the application of small invert traps to localise the deposition of sediments in sewers at accessible points for collection. New guidance has been produced for trap siting and this has been linked to a risk-cost-effectiveness assessment procedure to enable system operators to approach in-sewer sediment management pro-actively rather than reactively as currently happens.

Erosion mechanisms in combined sewers and the potential for pollutant release to receiving waters and water treatment plants

The problems associated with solids in sewerage systems result in common difficulties such as blockages and flooding and the subsequent maintenance requirements have been well documented. Concerns regarding pollutant release have also been demonstrated, with the contribution from in-sewer solids to the quality of the flow during a storm event being especially significant. These events known as "foul flushes" in combined sewers typically occur in the initial period of storm flows, when the concentration of suspended sediments and other pollutants are significantly higher than at other times. Traditionally impacts from these events have been related to the suspended solids phase of the flow passing through a CSO structure. It is now apparent that much of the suspended load originates from solids eroded from the bed. The "near bed solids" which are re-entrained into the flow, together with solids eroded from the bulk bed, account for large changes in the suspended sediment concentration under time varying flow conditions. The influence of these eroded solids and their potential impact on receiving waters and treatment plants will be reviewed using data obtained from field studies carried out in the main Dundee interceptor sewer in Scotland. This paper describes some of the methods employed to investigate the characteristics of the pollutants associated with solids erosion in combined sewers.

[Biological, familial and metabolic characteristics of infantile and juvenile obesity]

BACKGROUND

Obesity is the most prevalent nutritional disease in people of less than 20 years old.

AIM

To report biological, familial and metabolic characteristics in obese children.

PATIENTS AND METHODS

A retrospective review of 187 children seen at obesity clinics and that had a complete metabolic study.

RESULTS

Ninety five prepuberal and 92 puberal children, aged 8.7 +/- 2.2 and 12.6 +/- 2.2 years old respectively, were studied. Body mass index was over 4 standard deviations in 48.4% of prepuberal children and in 39.1% of puberal children. Paternal obesity was twice more prevalent (30.2%) than in the general population. The daily caloric intake and basal metabolic rate (BMR) were within the normal range; nevertheless there was a positive caloric balance due to minimal physical activity. The mean daily fat intake was normal (26.4 +/- 8.5 and 25.3 +/- 9.1% of total calories in prepuberal and puberal children respectively). The daily fiber intake was under 70% of recommendation. The total cholesterol was over 200 mg/dl in 26.6 and 23.9% of prepuberal and puberal children. LDL cholesterol was over 130 mg/dl in 27.3 and 26.6% and triacylglycerol was over 150 mg/dl in 16.9 and 25% of prepuberal and puberal children respectively. Basal serum insulin was over 20 uIU/ml in 27.7 and 42.2% of prepuberal and puberal children, respectively. Post glucose serum insulin was over 60 uIU/ml in 40 and 63% of prepuberal and puberal children, respectively.

CONCLUSIONS

Infantile and juvenile obesity is a chronic disease with a high incidence of metabolic alterations.

Marine-based waste stabilisation ponds: an evaluation of the hydraulic viability

Marine-Based Waste Stabilisation Ponds, formed by floating boom/skirt curtain enclosures anchored in sheltered waters, have recently been proposed for provision of low-cost effluent treatment facilities where land availability is limited in rapidly expanding coastal cities in the Third World. This paper outlines findings from a viability assessment, which drew on a preliminary site evaluation and baseline environmental survey (for a site in sheltered waters in the Far East), laboratory studies involving scale model tests in wave/wind/current flumes, and a structural and design loading study. It focuses on hydraulic and hydrodynamic considerations and reports the study's conclusions.

Novel boom/skirt systems for improvement of water quality in estuarial impoundments subject to saline influx

The recent popularity of esturial barrage construction in the UK has been driven largely by commercial and amenity interests arising from the need to rehabilitate tracts of derelict urban land. Formation of a permanent water body to replace the tidal regime hides unsightly mud banks and facilities ready access for water based recreation. Unfortunately, in most cases, and presumably arising from upstream extreme flood risk assessment, the barrier is designed to overtop under the highest (spring) tidal peaks so allowing a substantial influx of heavier saltwater into the impoundment on a regular basis. This might well substantially exceed influx via any navigational lock operations. The problem created by the salt water is that its greater density causes stratification in the impounded water body. In times of low freshwater flow little mixing takes place and the normal action of the wind, in circulating and aerating the water body, will only extend within the lighter and often thin surface freshwater layer. The consequence is that little reoxygenation of the lower layers takes place leading to depressed dissolved oxygen levels and possible anoxia. Sluice provision in the barrage may be ineffective in expelling the saline layers, so this water remains near stagnant and deteriorates in quality due to sediment oxygen demands until a major fluvial flood, or new saline influx, is able to effectively mix the waters. Conventional continuous surface releases through fish pass and/or by crest overspill ensure the preferential release of the freshwater rather than the problematic saltwater. Retrofitting of novel low cost floating boom/skirt baffle system is proposed here for alleviation of the problem.

Safety of withholding heparin in pregnant women with a history of venous thromboembolism. Recurrence of Clot in This Pregnancy Study Group

BACKGROUND

Women with a history of venous thromboembolism may be at increased risk for venous thromboembolic events during pregnancy. In these women, the decision to give or withhold heparin in the antepartum period is controversial, because accurate estimates of the frequency of recurrent thromboembolic events if antepartum heparin is withheld are not available.

METHODS

We prospectively studied 125 pregnant women with a single previous episode of venous thromboembolism. Antepartum heparin was withheld, but anticoagulant therapy was given for four to six weeks post partum. Our primary objective was to determine the rate of antepartum recurrence of venous thromboembolism. Laboratory studies were performed to identify thrombophilia in 95 women.

RESULTS

Three of the 125 women (2.4 percent) had an antepartum recurrence of venous thromboembolism (95 percent confidence interval, 0.2 to 6.9 percent). There were no recurrences in the 44 women who had no evidence of thrombophilia and who also had a previous episode of thrombosis that was associated with a temporary risk factor. Among the 51 women with abnormal laboratory results or a previous episode of idiopathic thrombosis, or both, 3 (5.9 percent) had an antepartum recurrence of venous thromboembolism (95 percent confidence interval, 1.2 to 16.2 percent).

CONCLUSIONS

The risk of recurrent antepartum venous thromboembolism in women with a history of venous thromboembolism is low, and therefore routine antepartum prophylaxis with heparin is not warranted.

CxGELSIX: a novel preparation of type VI collagen with possible use as a biomaterial

PURPOSE

This study was initiated to evaluate tissue acceptance and stability of a novel type VI collagen preparation (CxGelsix) as a biomaterial in the rabbit corneal stroma. We hypothesized that CxGelsix, embedded intrastromally, does not have any adverse affect on surrounding corneal tissues, and remains intact in the presence of an acute inflammatory reaction during corneal wound healing.

METHODS

Type VI collagen was extracted and purified from rabbit corneal stroma under nondenaturing conditions. This preparation, Gelsix, was concentrated and cross-linked with polyethylene glycol to produce a transparent film (CxGelsix). Discs of CxGelsix, 4.0-mm diameter, 9- to 35-microm thick were implanted intrastromally and clinically examined periodically for 4 months. In another experiment, implantation of CxGelsix, 2.0-mm-diameter, was followed by corneal wounding adjacent to the implant and examined clinically for 30 weeks. At the end of these periods, the tissues from these experiments were processed for light and transmission electron microscopy.

RESULTS

An intralamellar 4.0-mm-diameter disc of CxGelsix does not alter the structure of corneal epithelium above the implant, suggesting normal transport of nutrients through CxGelsix. Moreover, no structural abnormalities were seen in the rest of the cornea, and the cornea remains transparent. Although the cornea accepts the presence of CxGelsix disc as judged by clinical criteria, gradual degradation of the implant is seen ultrastructurally. CxGelsix is remarkably stable despite its exposure to endogenous enzymes during inflammation and wound healing. Partial degradation of the implant occurs only after many months, and it is gradually replaced with bundles of fine collagen fibrils reminiscent of normal cornea.

CONCLUSION

The results of this study suggest that CxGelsix is potentially useful as a biomaterial.

Nonintrusive optical measurements of aircraft engine exhaust emissions and comparison with standard intrusive techniques

Nonintrusive systems for the measurement on test rigs of aeroengine exhaust emissions required for engine certification (CO, NO(x), total unburned hydrocarbon, and smoke), together with CO(2) and temperature have been developed. These results have been compared with current certified intrusive measurements on an engine test. A spectroscopic database and data-analysis software has been developed to enable Fourier-transform Infrared measurement of concentrations of molecular species. CO(2), CO, and NO data showed agreement with intrusive techniques of approximately ?30%. A narrow-band spectroscopic device was used to measure CO(2) (with deviations of less than ?10% from the intrusive measurement), whereas laser-induced incandescence was used to measure particles. Future improvements to allow for the commercial use of the nonintrusive systems have been identified and the methods are applicable to any measurement of combustion emissions.

An exploration of inter-relationships between contact angle, inverse phase gas chromatography and triboelectric charging data

Surfaces of pharmaceutical powders have been assessed using contact angle, inverse phase gas chromatography (IGC) and triboelectric (electrostatic) charging techniques. The suitability of the Dynamic Angle Tester (DAT), an instrument based on the sessile drop technique, in determining contact angles and then the surface energy of pharmaceutical powders was assessed. The dispersive components of the surface energy of powders determined from the DAT and IGC method ranked the powders in the same order. The dispersive component values obtained by IGC were, as expected, higher than those from the DAT, due to IGC probing the highest energy sites on the powder surface. IGC and triboelectric studies allow materials to be characterised in terms of their electron donating-accepting tendencies, so inter-relationships between the data from the two techniques were explored. Although the data set was limited, there appeared to be a correlation between the charges developed by the powders on contact with stainless steel and the ratio of the electron-donating to electron-accepting tendencies of the materials as obtained from IGC.

[Prevention and treatment of obesity since childhood: strategy to decrease the non transmissible chronic diseases in adult]

The prevalence of obesity among children and teenagers is increasing by 1.5% per year, probably due to a higher consumption of highly caloric foods and to physical inactivity. Hypercholesterolemia, increased insulin levels and high blood pressure of childhood obesity, precede atherosclerosis, coronary artery disease, diabetes and hypertension in adulthood. The prevention of childhood obesity is an efficient strategy to decrease the prevalence of non transmissible chronic diseases in the adult. The recommendations of experts committees for the prevention, diagnosis and treatment of childhood obesity are reviewed. They aim at a change in dietary habits and increasing physical activity. A well balanced healthy diet and a decrease in physical inactivity time will result in a successful treatment approach for obesity.

Abdominal content containment: practicalities and outcome

BACKGROUND

Alternatives to fascial closure of the abdominal wall are increasingly used in critically ill patients. They pose practical and logistical problems in management which are described in this single-institution study.

METHODS

Between January 1994 and December 1997, 157 predominantly young male patients (100 trauma and 57 non-trauma) underwent temporary abdominal content containment (t-ACC) using plastic bags or polyglactin mesh. Indications for t-ACC were severe sepsis requiring reoperation, abdominal compartment syndrome, abdominal wall tissue loss or a combination of these. A total of 385 laparotomies were performed.

RESULTS

Two t-ACC procedures failed owing to technical error and two were complicated by enteric fistulas. Six patients underwent early definitive abdominal closure within 15 days. The remaining survivors had a protracted hospital stay (mean(s.d.) 44.6(26.6) days) and all developed incisional hernias which were challenging to repair. The overall mortality rate was 44 per cent.

CONCLUSION

Plastic bags were cheaper and as effective as polyglactin mesh for t-ACC. Survivors require a multidisciplinary approach in management, undergo a protracted hospital stay and later need complex incisional hernia repairs.

Potential roles of metalloprotease mediated ectodomain cleavage in signaling by the endothelial receptor tyrosine kinase Tie-1

The orphan receptor tyrosine kinase Tie-1 is expressed predominantly in endothelial cells. Expression of this receptor is increased in physiologic angiogenesis and pathologic situations including tumor growth and arteriovenous malformations. Tie-1 is essential for vascular development where it acts in later stages of angiogenesis to suppress endothelial activation and stabilize the newly formed vessel. Stimulation of protein kinase C in endothelial cells results in endoproteolytic cleavage of Tie-1, releasing the extracellular ligand-binding domain of the receptor. We show that this is mediated by a metalloprotease. Immunoprecipitation and immunoblotting of lysates prepared from human placentas confirm that Tie-1 truncation occurs in vivo. We propose cleavage of this receptor may be a mechanism for inducing vessel destabilization by preventing ligand-activated signaling through Tie-1. Using an antibody that recognizes the carboxy terminus of the intracellular domain, we show that the Tie-1 endodomain formed on cleavage persists as a cell-associated fragment for several hours. Subcellular fractionation reveals this tyrosine kinase containing receptor fragment to be localized in the membrane fraction of the cell. Immunoprecipitation with antibodies recognizing phosphotyrosine demonstrates that cleavage of Tie-1 stimulates association of newly generated endodomain with cellular phosphoproteins. Furthermore, there was a marked induction of tyrosine phosphorylation of several proteins after PMA-induced endodomain generation. These data indicate that ectodomain cleavage may be a mechanism for down-regulating ligand-induced signaling through Tie-1 while activating an alternative ligand-independent signaling pathway in endothelial cells. Ectodomain cleavage occurs in some other receptor tyrosine kinases. We suggest that rather than solely being a means of down-regulating receptor activity, ectodomain cleavage may be a novel way for a receptor to switch between two alternative signaling pathways.

Mivacurium compared with three different doses of suxamethonium for nasotracheal intubation

Suxamethonium in the doses of 1.0, 0.5 and 0.25 mg/kg was compared with mivacurium 0.15 mg/kg in 80 patients requiring nasotracheal intubation for maxillofacial surgery in a double-blind randomized controlled trial. Anaesthesia was induced with thiopentone 5 mg/kg and alfentanil 15 micrograms/kg. Patients were randomly allocated to one of the four relaxant groups. Anaesthesia was maintained with enflurane in 70% nitrous oxide and 30% oxygen and analgesia provided with intravenous pethidine 0.5 to 1.5 mg/kg and rectal indomethacin 100mg. All patients given mivacurium or suxamethonium 1 mg/kg had acceptable intubating conditions. Significantly fewer patients given suxamethonium 0.5 mg or 0.25 mg/kg had acceptable intubating conditions (90% and 70% respectively) (P = 0.003). Poor intubating conditions requiring additional relaxation were seen in two patients given suxamethonium 0.25 mg/kg and two given 0.5 mg/kg, while no patients given suxamethonium 1.0 mg/kg or mivacurium 0.15 mg/kg required additional relaxation (P = 0.004). Only four patients had postoperative myalgia, all of whom were given suxamethonium 0.5 mg/kg or more but no significant difference between groups could be demonstrated.

Beta-ig. Molecular cloning and in situ hybridization in corneal tissues

PURPOSE

To identify a protein that copurifies with type VI collagen from rabbit cornea and to determine its cell source in rabbit corneal tissues by in situ hybridization.

METHODS

Type VI collagen was extracted from cornea with urea and purified by ammonium sulfate precipitation and gel chromatography. The purity of the collagen was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). On reduction with mercaptoethanol or dithiothreitol, the alpha chains of type VI collagen ran into the gel. In addition to the type VI collagen polypeptides, an extra 68-kDa protein band appeared, suggesting that this protein is present as a large molecular weight component before reduction. Amino acid sequencing indicated that protein was related to beta ig-h3 from humans. Western blot analysis was used to determine immunologic similarity to this human protein. A rabbit stromal cell cDNA library was screened with human beta ig-h3 cDNA probe. Positive clones were sequenced and analyzed for sequence homology. Oligonucleotide probes prepared from rabbit cDNA sequences were used for Northern blot analysis and in situ hybridization of corneal tissues.

RESULTS

Electroblotting of the SDS-PAGE and amino acid sequence analysis of the first 10 N-terminal amino acids of the 68-kDa band gave 100% homology with a known protein produced by human adenocarcinoma cells, beta ig-h3. This 68-kDa protein was identical immunologically to beta ig-h3 by Western blot analysis. Sequence analysis of a rabbit cDNA clone contained the whole coding region and had high identity with both human beta ig-h3 and mouse beta ig-m3. The deduced amino acid sequence had 92% identity with these species. An oligonucleotide probe from the rabbit cDNA sequence detected a single band of mRNA from cultures of stromal cells consistent in size with human beta ig-h3 mRNA. The authors refer to the rabbit form of beta ig-h3 as beta ig because the protein was obtained from normal rabbit cornea and the mRNA comes from primary cultures of rabbit stromal cells and not from a cloned cell line. In situ hybridization of rabbit corneal tissue indicated that the beta ig mRNA is located primarily in the epithelium of normal adult cornea, in fetal stromal cells, and both endothelium- and stroma-derived cells in healing corneal wounds. Normal adult endothelium and stroma did not show beta ig mRNA label.

CONCLUSIONS

The highly conserved amino acid sequence homology between the human, mouse, and rabbit proteins and the temporal expression of beta ig message during corneal healing and development suggest this protein plays an important role in the morphogenesis of corneal tissues.

[Bone mass in celiac patients]

Bone mineral content was measured in the whole body, the spine (L2-L4) and hip by Dual Photonic Absorpciometry (densitometer Norland 2600 Gd-153), in seventeen celiac patients, aged 6 to 12 years, with good adherence to the gluten free diet. The diagnosed was made before 30 months of age in 50% of cases. Average treatment duration was 69.8 +/- 36 months. The randomly selected control group was composed of 48 school age children, of the same age and sex of patients. Total bone mass (TBM) and bone mineral density (BMD) were expressed as Z scores on the basis of normal values established by the authors in Chilean children. Celiac patients had lower TBM and BMD of whole body, than controls (-1.11 +/- 0.94 vs 0.00 +/- 0.85 and -0.59 +/- 0.76 vs 0.06 +/- 0.84, respectively) and at the spine (-0.79 +/- 1.04 vs 0.003 +/- 0.92 and -1.49 +/- 0.99 vs 0.06 +/- 0.87 respectively). A lower TBM was founded at the hip (-0.62 +/- 1.28 vs -0.08 +/- 0.82) without differences in BMD. Celiac patients had a lower bone mass than controls despite early diagnosis and good compliance with the gluten-free diet. These differences could not be atributed entirely to the lower height of celiac patients. These results suggest that celiac patients constitute a risk group for development of osteoporosis later in life. This fact should be taken into consideration in the treatment of this condition.

Population dynamics, intervention and survival in African wild dogs (Lycaon pictus)

The demography of Serengeti wild dog study packs and their extinction in 1991 was documented by Burrows et al. (1994). One explanation for pack loss compatible with demographic evidence was viral disease induced by stress caused by intervention (vaccination, immobilization and radio-collaring). Several studies claim to reject this hypothesis. However, cortisol levels measured in immobilized Lycaon, whose pathogen exposure is unknown, do not demonstrate that interventions in the Serengeti were benign. The analysis of survivorship in Lycaon in other ecosystems minimized the chance of demonstrating any effect of intervention and failed to consider vaccinations as intervention. There is now evidence that intervention significantly decreased survivorship of Masai Mara Lycaon. Further simulations of the likelihood of population extinction in Serengeti Lycaon, evidence of limited population variability and a small scaling factor in Serengeti Lycaon strengthen Burrows et al.'s conclusion that the extinction was unlikely to be due to chance alone. Although some studies claim that Lycaon conservation is doomed without intervention, to date vaccinations, blood sampling and radio-telemetry have contributed little to Lycaon conservation. All studies fail to disprove the Burrows hypothesis or provide convincing alternatives.

[Bone mineralization and calcium intake in Chilean school children]

Bone mineralization was evaluated in 36 school age children with calcium intake below 50% of Recommended Dietary Allowances (RDA), and compared with 28 school age children with calcium intake higher than 100% of the RDA. The total group was aged between 86 and 178 months. The calcium intake was evaluated by 24 hours recordatory survey. Height for age and weight for height were evaluated according to WHO tables. Puberal development was evaluated according to Tanner stages. Bone mineral density (BMD) and total bone mass (TBM) of whole body, spine and femoral neck were measured with Norland 2600 densitometer. School age children with intakes below 50% of RDA had lower height for age adequation (97.7 +/- 4.0%), whole body TBM adequation (98.9 +/- 17.9%) and BMD adequation (97.8 +/- 7.9%) than those ingesting more than 100% of the RDA (115.9 +/- 17.4%), (109.7 +/- 18.0%) and (104.7 +/- 11.1%) respectively. In spine, however, there was a clear tendency to be lower, there were no significant differences between both groups. There were no differences in femoral necks BMD adequation, or TBM adequation between both groups. These results show that children with calcium intake below 50% of the recommendation has lower adequation of statural growth and bone mineralization. The role of calcium in the differences found in this study is discussed.

[Bone mineralization in adolescents suffering from postnatal malnutrition]

The bone mineralization of 6 male and 18 female adolescents with a mean age of 12 years and 11 months, who had suffered severe, early, postnatal protein-energy undernutrition, was analyzed. These patients have been followed up at our Institute since their nutritional rehabilitation. Bone mineralization was measured by bone dual isotopic densitometry (Gd 153). These results were compared with those of normal school-age Chilean children of the same age and sex. Weight for height of adolescent who had suffered from undernutrition was similar to the controls, and both were over 100% of the standard. Adequation of height for age was significantly less in those with previous history of undernutrition. Densitometries showed that adolescents with a past history of undernutrition had lower total bone mass in whole body, spine and femoral neck; differences disappeared when expressed per 100 cm of body height. There were no differences in bone mineral density in the different area measurements. It is concluded that the possible alterations that undernutrition produces in bone mineralization probably recover after nutritional rehabilitation, adequate nutritional follow up and health support.

Localization of type XII collagen in normal and healing rabbit cornea by in situ hybridization

To identify the cell types responsible for type XII collagen synthesis in normal and healing rabbit cornea, a partial cDNA sequence of rabbit type XII collagen, obtained from an adult rabbit cornea cDNA library, was used to develop highly specific oligonucleotide probes for Northern blot analysis and in situ hybridization. Approximately 2000 bases of a type XII collagen 2.2 kb cDNA clone were sequenced. Comparative sequence analysis of the bases showed a 74% identity with chick alpha 1 (XII) chain of type XII collagen. The deduced amino acid sequence indicated a 72% identity with chick type XII collagen. Northern blot analysis showed that cultures of cornea stromal and endothelial cells each contain two RNA species, greater than 10 kb, that hybridize to rabbit type XII collagen oligonucleotide probes. Although normal stromal cells failed to show type XII collagen mRNA, normal endothelial cells contain mRNA for this collagen. These results indicate that endothelium of normal rabbit cornea has a potential to synthesize type XII collagen. During corneal wound healing, both endothelium-derived and stroma-derived cells in the developing scar tissue contained type XII mRNA. In view of the known presence of type XII collagen in corneal stromas from chick and mouse, the distribution of mRNA in normal cornea is puzzling.

[Psychosocial and familial variables associated with teenage pregnancy]

Preventive measures for teenage pregnancy (TP), would decrease infant mortality, early undernutrition and statal social expenditure. The cost of programs for TP would decrease with a sensitive risk indicator. We searched some pysoshocial and familial parameters, useful to built up this indicator. Self esteem (Piers-Harris test), intrafamilial relationship (Familial Apgar of Magdaleno) and the use of break time were studied in 60 pregnant teenagers (PT), 60 non pregnant teenagers at a low risk of pregnancy (LRP) and 60 non pregnant teenagers at a high risk of pregnancy (HRP). PT and HRP showed lower self esteem than LRP (88.3, 70.0 Y 41.6% respectively, under 7 points) lower familial Apgar (61.6, 50 y 8.3% under score 6) and lower the quality of use of break time (66.7, 74.1 y 31.7% respectively with regular or deficient quality). The self esteem, intrafamilial relationship hand use of break time were associated to early pregnancy and high risk of pregnancy. These parameters are important to built up a sensitive risk indicator of early pregnancy in order to decrease the prevalence of this serious problem.

Captive care: changes in prison nursing

Nursing in prisons is a new growth area. This article highlights how the major developments in mental health provision and changing health patterns in inmate populations have influenced the evolution of specialist nursing services for prisoners. Many issues concerning the role, training and salaries of nurses who work in prisons remain unresolved, however, and the complex ethical and legal conflicts remain ever-present in the prison environment.