Morphology and size-distribution of sound and acid-treated enamel crystallites.

Citric acid dissolves crystallites of enamel by initially etching out approximately hexagonal holes in the core of the crystallites, parallel to their long axis. Such acid-treatment influences the crystallite diameter only slightly since the distribution of the diameters of crystallites with a hollow core is not essentially different from those found in sound enamel. In both cases, the average diameter is 37 nm. Crystallites having a central defect and an outer diameter of about 40 nm are split into two parts of approximatley 15 nm in diameter following acid treatment. The central defect is caused exclusively by the acid and not by damage from the electron beam, nor by a combination of acid treatment and electron beam damage.     

The effect of a reduced sodium intake on post-renal transplantation hypertension in rats

In an experimental model of post-renal transplantation hypertension in rats, we studied the effect of a reduction of sodium intake on the development of this type of hypertension. Systolic blood pressure, plasma renin concentration and renal function were measured regularly in recipients of an allogeneic kidney transplant that had previously undergone active immunological enhancement. Transplant recipients on a normal diet showed a rise in systolic blood pressure during the second week after transplantation. The systolic blood pressure of recipients on a low sodium diet remained normotensive throughout the 15 weeks follow-up period. The plasma renin concentration was low in the hypertensive recipients on a normal diet, as compared with unilaterally nephrectomized controls. Although the plasma renin concentration of recipients on a low sodium diet fell below that of unilaterally nephrectomized controls on a low sodium diet, it was higher than that of recipients on a normal diet. The renal function of transplant recipients was greatly reduced compared with that of control rats. The glomerular filtration rate was reduced to a greater extent than the effective renal plasma flow. In a separate experiment it was revealed that a similar reduction in the glomerular filtration rate of kidneys permanently damaged by temporary ischaemia did not result in an increase in the systolic blood pressure. Survival up to 6 weeks after transplantation was the same for both groups of recipients. Recipients on a low sodium diet, however, showed a better 15 weeks survival, probably owing to the absence of hypertension in this group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Measuring activity limitations in walking: development of a hierarchical scale for patients with lower-extremity disorders who live at home

OBJECTIVE: To develop a hierarchical scale that measures activity limitations in walking in patients with lower-extremity disorders who live at home. DESIGN: Cross-sectional study. SETTING: Orthopedic workshops and outpatient clinics of secondary and tertiary care centers. PARTICIPANTS: Patients (N=981; mean age +/- standard deviation, 58.6+/-15.4 y; 46% men) living at home, with different lower-extremity disorders: stroke, poliomyelitis, osteoarthritis, amputation, complex regional pain syndrome type I, and diabetic and degenerative foot disorders. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: (1) Fit of the monotone homogeneity model, indicating whether items can be used for measuring patients; (2) fit of the double monotonicity model, indicating invariant (hierarchical) item ordering; (3) intratest reliability, indicating repeatability of the sum score; (4) robustness, addressing the clinimetric properties within subgroups of patients; and (5) differential item functioning, addressing the validity of comparisons between subgroups of patients. RESULTS: Thirty-five of 41 dichotomous items had (1) good fit of the monotone homogeneity model (coefficient H=.50), (2) good fit of the double monotonicity model (coefficient H(T)=.33), (3) good intratest reliability (coefficient rho=.95), (4) satisfactory robustness (within subgroups of patients defined by age, sex, and diagnosis), and (5) some differential item functioning (6 items in amputees compared with nonamputees). CONCLUSIONS: A hierarchical scale, with excellent scaling characteristics, was developed to measure activity limitations in walking in patients with lower-extremity disorders who live at home. The measurements should be interpreted cautiously when making comparisons between amputees and nonamputees.     

Visual Feedback and Weight Reduction of a Grip Strength Dynamometer Do Not Increase Reliability in Healthy Children

Study DesignTest–retest reliability study on grip strength in children.IntroductionMeasuring grip strength in children is difficult because of the weight and size of the instrument, brief attention span, and possible lack of task understanding. Therefore, adaptations to the measurement protocols to improve reliability would be very important for research and clinical evaluation.PurposeIn this study, we compared the reliability of a grip strength dynamometer (Lode dynamometer, Lode BV, Groningen, The Netherlands) using three different protocols.MethodsTest–retest reliability of the American Society of Hand Therapists protocol in 104 healthy children (4–12 years) was compared with the reliability in 63 healthy children of a visual feedback protocol and a suspension protocol reducing weight of the instrument.ResultsFor the total group, intraclass correlation coefficients for the dominant and nondominant hands were 0.95–0.97 for all protocols, indicating that all three protocols were reliable.ConclusionNo statistically significant difference was found among the reliability of the different protocols, but the suspension protocol produced small but significantly higher force levels.Level of EvidenceNot applicable.     

Time dependence of coupling in frequency-scaled bimanual coordination

Prior research has shown that fluctuations in the relative phase of bimanual coordination do not reflect a white Gaussian noise process. The present study furthered the examination of time-dependent properties in bimanual coordination by comparing the magnitude of relative phase variability and the degree of effector independence within the time domain. The original Kelso (1984) [10] bimanual frequency-scaling protocol was reproduced in which phase transitions from antiphase to in-phase were induced with increasing movement frequency. The results showed that as movement frequency was scaled-up the amount of relative phase variability increased and the effector movements became more dependent prior to the transition. This is consistent with previous modeling showing that stronger effector coupling can prevent the occurrence of phase transitions when long range correlations in relative phase are present. It appears that, as movement frequency is scaled up, increases in effector coupling strength minimize loss of pattern stability and delay the onset of phase transitions.     

The micro-Petri dish, a million-well growth chip for the culture and high-throughput screening of microorganisms

A miniaturized, disposable microbial culture chip has been fabricated by microengineering a highly porous ceramic sheet with up to one million growth compartments. This versatile culture format, with discrete compartments as small as 7 x 7 mum, allowed the growth of segregated microbial samples at an unprecedented density. The chip has been used for four complementary applications in microbiology. (i) As a fast viable counting system that showed a dynamic range of over 10,000, a low degree of bias, and a high culturing efficiency. (ii) In high-throughput screening, with the recovery of 1 fluorescent microcolony in 10,000. (iii) In screening for an enzyme-based, nondominant phenotype by the targeted recovery of Escherichia coli transformed with the plasmid pUC18, based on expression of the lacZ reporter gene without antibiotic-resistance selection. The ease of rapid, successive changes in the environment of the organisms on the chip, needed for detection of beta-galactosidase activity, highlights an advantageous feature that was also used to screen a metagenomic library for the same activity. (iv) In high-throughput screening of >200,000 isolates from Rhine water based on metabolism of a fluorogenic organophosphate compound, resulting in the recovery of 22 microcolonies with the desired phenotype. These isolates were predicted, on the basis of rRNA sequence, to include six new species. These four applications suggest that the potential for such simple, readily manufactured chips to impact microbial culture is extensive and may facilitate the full automation and multiplexing of microbial culturing, screening, counting, and selection.     

Burden and rates of treatment and control of cardiovascular disease risk factors in obesity: the Framingham Heart Study

OBJECTIVE— Obesity is associated with an increased risk for cardiovascular disease (CVD). We sought to determine rates of treatment and control of CVD risk factors among normal weight, overweight, and obese individuals in a community-based cohort.RESEARCH DESIGN AND METHODS— Participants free of CVD (n = 6,801; mean age 49 years; 54% women) from the Framingham Offspring and Third Generation cohorts who attended the seventh Offspring examination (1998–2001) or first Third Generation (2002–2005) examination were studied.RESULTS— Obese participants with hypertension were more likely to receive antihypertensive treatment (62.3%) than normal weight (58.7%) or overweight (59.0%) individuals (P = 0.002), but no differences in hypertension control across BMI subgroups among participants with hypertension were observed (36.7% [normal weight], 37.3% [overweight], and 39.4% [obese]; P = 0.48). Rates of lipid-lowering treatment were higher among obese participants with elevated LDL cholesterol (39.5%) compared with normal weight (34.2%) or overweight (36.4%) participants (P = 0.02), but control rates among those with elevated LDL cholesterol did not differ across BMI categories (26.7% [normal weight], 26.0% [overweight], and 29.2% [obese]; P = 0.11). There were no differences in diabetes treatment among participants with diabetes across BMI groups (69.2% [normal weight], 50.0% [overweight], 55.0% [obese]; P = 0.54), but obese participants with diabetes were less likely to have fasting blood glucose <126 mg/dl (15.7%) compared with normal weight (30.4%) or overweight (20.7%) participants (P = 0.02).CONCLUSIONS— These findings emphasize the suboptimal rates of treatment and control of CVD risk factors among overweight and obese individuals.Obesity affects more than one-third of the adult population in the U.S. Excess weight is associated with multiple cardiovascular disease (CVD) risk factors, including hypertension, dyslipidemia, diabetes, and the metabolic syndrome.Although the incidence and mortality of CVD have declined markedly during the past decades, some studies suggested that the increasing prevalence of obesity and diabetes may have slowed this rate of decline (1). In addition, recent data suggest that the prevalence of chronic kidney disease is increasing, in part because of the increasing rates of diabetes (2). Unfortunately, the efficacy of current therapies for obesity, including lifestyle and pharmacological interventions, is limited (3). Although bariatric surgery is an effective method of weight loss among severely obese individuals, eligibility criteria limit its use to only the most significantly affected patients.Given the current limitations of effective weight loss therapies, minimizing the risk of complications of obesity and diabetes due to CVD risk factors is essential. Few studies have focused on a comprehensive approach to CVD risk factor burden, treatment, and control among obese individuals. Therefore, the aim of this study was to examine the burden of CVD risk factors as well as rates of treatment and control among normal weight, overweight, and obese individuals in an unselected population-based cohort. As abdominal fat accumulation is strongly associated with metabolic and CVD risk factors, and as recent guidelines have emphasized the importance of measuring waist circumference as part of clinical cardiovascular risk assessment, we also studied individuals with and without abdominal obesity.     

(-)-Adrenaline elicits positive inotropic, lusitropic, and biochemical effects through β2-adrenoceptors in human atrial myocardium from nonfailing and failing hearts, consistent with Gs coupling but not with Gi coupling

Activation of either coexisting β₁- or β₂-adrenoceptors with noradrenaline or adrenaline, respectively, causes maximum increases of contractility of human atrial myocardium. Previous biochemical work with the β₂-selective agonist zinterol is consistent with activation of the cascade β₂-adrenoceptors→Gsα-protein→adenylyl cyclase→cAMP→protein kinase (PKA)→phosphorylation of phospholamban, troponin I, and C-protein→hastened relaxation of human atria from nonfailing hearts. However, in feline and rodent myocardium, catecholamines and zinterol usually do not hasten relaxation through activation of β₂-adrenoceptors, presumably because of coupling of the receptors to Gi protein. It is unknown whether the endogenously occurring β₂-adrenoceptor agonist adrenaline acts through the above cascade in human atrium and whether its mode of action could be changed in heart failure. We assessed the effects of (-)-adrenaline, mediated through β₂-adrenoceptors (in the presence of CGP 20712A 300 nM to block β₁-adrenoceptors), on contractility and relaxation of right atrial trabecula obtained from nonfailing and failing human hearts. Cyclic AMP levels were measured as well as phosphorylation of phospholamban, troponin I, and protein C with Western blots and the back-phosphorylation procedure. For comparison, β₁-adrenoceptor-mediated effects of (-)-noradrenaline were investigated in the presence of ICI 118,551 (50 nM to block β₂-adrenoceptors). The positive inotropic effects of both (-)-noradrenaline and (-)-adrenaline were accompanied by reductions in time to peak force and time to reach 50% relaxation. (-)-Adrenaline caused similar positive inotropic and lusitropic effects in atrial trabeculae from failing hearts. However, the inotropic potency, but not the lusitropic potency, of (-)-noradrenaline was reduced fourfold in atrial trabeculae from heart failure patients. Both (-)-adrenaline and (-)-noradrenaline enhanced cyclic AMP levels and produced phosphorylation of phospholamban, troponin I, and C-protein to a similar extent in atrial trabeculae from nonfailing hearts. The hastening of relaxation caused by (-)-adrenaline together with the PKA-catalyzed phosphorylation of the three proteins involved in relaxation, indicate coupling of β₂-adrenoceptors to Gs protein. The phosphorylation of phospholamban at serine16 and threonine17 evoked by (-)-adrenaline through β₂-adrenoceptors and by (-)-noradrenaline through β₁-adrenoceptors was not different in atria from nonfailing and failing hearts. Activation of β₂-adrenoceptors caused an increase in phosphorylase a activity in atrium from failing hearts further emphasizing the presence of the β₂-adrenoceptor–Gsα-protein pathway in human heart. The positive inotropic and lusitropic potencies of (-)-adrenaline were conserved across Arg16Gly- and Gln27Glu-β₂-adrenoceptor polymorphisms in the right atrium from patients undergoing coronary artery bypass surgery, chronically treated with β₁-selective blockers. The persistent relaxant and biochemical effects of (-)-adrenaline through β₂-adrenoceptors and of (-)-noradrenaline through β₁-adrenoceptors in heart failure are inconsistent with an important role of coupling of β₂-adrenoceptors with Giα-protein in human atrial myocardium.     

Intussusception in a tropical country: comparison among patient populations in Jakarta, Jogyakarta, and Amsterdam.

BACKGROUND: Intussusception is the most common cause of intestinal obstruction in young children, and high mortality rates remain a problem in developing countries. The purpose of this study was to describe and elucidate the differences in outcome between groups of children with intussusception in Indonesia, a developing country, and The Netherlands, a developed country. METHODS: In this retrospective review, 176 patients were studied in three types of hospitals. A comparison was made among children treated at a primary care rural hospital in Indonesia, at a secondary care urban hospital in Indonesia, and at a tertiary care urban hospital in The Netherlands. RESULTS: Children in the rural community hospital in Indonesia were more severely ill at arrival and had a significantly longer duration of symptoms, an increased incidence of nonviable bowel, and a mortality rate of 20%, in contrast to a mortality rate of 3% in the urban hospital in Indonesia and no deaths in the Dutch hospital. CONCLUSIONS: The mortality of children with intussusception in rural Indonesia is much higher than in urban Indonesia or in The Netherlands, probably because of delayed treatment, which results in more patients undergoing surgery in worse physical condition.