Application of a comprehensive subtelomere array in clinical diagnosis of mental retardation

In 2-8% of patients with mental retardation, small copy number changes in the subtelomeric region are thought to be the underlying cause. As detection of these genomic rearrangements is labour intensive using FISH, we constructed and validated a high-density BAC/PAC array covering the first 5 Mb of all subtelomeric regions and applied it in our routine screening of patients with idiopathic mental retardation for submicroscopic telomeric rearrangements. The present study shows the efficiency of this comprehensive subtelomere array in detecting terminal deletions and duplications but also small interstitial subtelomeric rearrangements, starting from small amounts of DNA. With our array, the size of the affected segments, at least those smaller than 5 Mb, can be determined simultaneously in the same experiment. In the first 100 patient samples analysed in our diagnostic practice by the use of this comprehensive telomere array, we found three patients with deletions in 3p, 10q and 15q, respectively, four patients with duplications in 9p, 12p, 21q and Xp, respectively, and one patient with a del 6q/dup 16q. The patients with del 3p and 10q and dup 12p had interstitial rearrangements that would have been missed with techniques using one probe per subtelomeric region chosen close to the telomere.     

Synthesis and Characterization of Segmented Poly(ether ester)s Containing H‐Bonding Units

A series of poly(ether ester)s containing different H‐bonding units (amide, carbamate, urea) was prepared by polycondensation in bulk, using Ti(OBu)₄ as a catalyst. The copolymers were obtained starting from PEG1000, 1,4‐butanediol, and a symmetrical, bis‐ester terminated monomer carrying H‐bonding units. These materials were designed for biomedical applications, in which ultimate biodegradability of the materials is required. The influence of the nature of the H‐bonding unit and of the length of the methylene spacer between H‐bonding groups on the thermal and solubility properties of copolymers was investigated. Amide containing copolymers were more thermally stable than ones containing carbamate, consistent with the observed behavior of the corresponding monomers. In most cases, differential scanning calorimetry (DSC) traces were quite complex because of phase separation and dependent on the applied cooling rate. Copolymers containing urea bonds were less soluble in most organic solvents, but their thermal properties were not significantly different than their amide containing counterparts.

Synthesis of amide‐based diester monomers.     

Copolymerization of ε-caprolactone and morpholine-2,5-dione derivatives

Novel biodegradable poly(ester-amide)s were prepared by ring-opening copolymerization of ε-caprolactone and 3- and/or 6-alkyl-substituted morpholine-2,5-dione derivatives. The copolymerizations were carried out in the bulk using stannous octoate as an initiator. Molecular weights of the copolymers ranged from 1,0 · 10⁴ to 8,3 · 10⁴ and decreased with increasing mole fractions of morpholine-2,5-dione derivatives in the feed. ¹³C NMR sequence analysis indicated that the copolymers had a random distribution of ε-oxycaproyl and depsipeptide units, which resulted from the occurrence of transesterification reactions during copolymerization. The results of the DSC measurements and ¹³C NMR sequence analysis showed a close relationship between the crystallinity and average length of ε-oxycaproyl blocks. Copolymers with a mole fraction of depsipeptide units smaller than 0,20 were semi-crystalline, whereas incorporation of larger amounts of depsipeptide units resulted in amorphous copolymers. The melting point depression as a function of the molar composition of the semi-crystalline copolymers was in good agreement with the melting point depression predicted by the Baur equation, which indicated the rejection of depsipeptide units from crystals consisting of ε-oxycaproyl units.     

Improving medical residents’ self-assessment of their diagnostic accuracy: does feedback help?

Advances in Health Sciences Education - When physicians do not estimate their diagnostic accuracy correctly, i.e. show inaccurate diagnostic calibration, diagnostic errors or overtesting can occur....     

Associations of Dietary Patterns with Incident Depression: The Maastricht Study

Our aim was to assess the association between a priori defined dietary patterns and incident depressive symptoms. We used data from The Maastricht Study, a population-based cohort study (n = 2646, mean (SD) age 59.9 (8.0) years, 49.5% women; 15,188 person-years of follow-up). Level of adherence to the Dutch Healthy Diet (DHD), Mediterranean Diet, and Dietary Approaches To Stop Hypertension (DASH) were derived from a validated Food Frequency Questionnaire. Depressive symptoms were assessed at baseline and annually over seven-year-follow-up (using the 9-item Patient Health Questionnaire). We used Cox proportional hazards regression analyses to assess the association between dietary patterns and depressive symptoms. One standard deviation (SD) higher adherence in the DHD and DASH was associated with a lower hazard ratio (HR) of depressive symptoms with HRs (95%CI) of 0.78 (0.69–0.89) and 0.87 (0.77–0.98), respectively, after adjustment for sociodemographic and cardiovascular risk factors. After further adjustment for lifestyle factors, the HR per one SD higher DHD was 0.83 (0.73–0.96), whereas adherence to Mediterranean and DASH diets was not associated with incident depressive symptoms. Higher adherence to the DHD lowered risk of incident depressive symptoms. Adherence to healthy diet could be an effective non-pharmacological preventive measure to reduce the incidence of depression.     

Ethnic Harassment and the Protective Effect of Positive Parenting on Immigrant Youths’ Antisocial Behavior

Background

The existing literature suggests that positive parenting might serve as a protective factor against immigrant adolescents’ engagement in externalizing difficulties when they are exposed to negative experiences of ethnic derogation. To date, little is known, however, about whether different dimensions of positive parenting may moderate the detrimental impact of ethnic harassment at school on immigrant youth’s antisocial behavior.

Objective

This study aimed to investigate which specific dimensions of positive parenting may act as a buffer against the detrimental impact of ethnic harassment at school on immigrant adolescents’ antisocial behavior (i.e., delinquency and violence).

Method

Using longitudinal data, we followed first- and second-generation immigrant adolescents (N?=?365; Mage?=?13.93, SD?=?.80; 46% girls; 37% first-generation) in Sweden over a period of one year. Data collection at Time 1 (T1) was completed in the spring semester of the school year, and Time 2 (T2) assessments took place a year after the first data collection. We ran a series of regressions analyses via the SPSS PROCESS macro for each dimension of positive parenting behavior and each type of antisocial behavior.

Results

We found that ethnically harassed immigrant adolescents who received parental warmth, perceived their influence on family decisions and whose parents were aware of their children’s daily activities were less likely to engage in delinquency and violence one year later. In addition, we saw that immigrant youth whose parents actively sought information about their offsprings’ lives were less prone to display violence in the face of ethnic harassment.

Conclusions

The results suggest that parents are important in overriding the noxious effects of negative peer interactions targeting their children’s ethnic background, even during an adolescence marked by significant changes in child–parent and child–peer relationships. These findings might inform the development of intervention components for testing in interventions studies aimed at preventing immigrant youths’ antisocial behavior and future involvement in violent criminal offences.

     

Mechanism of bone incorporation of beta-TCP bone substitute in open wedge tibial osteotomy in patients

A histological study was performed of bone biopsies from 16 patients (17 biopsies) treated with open wedge high tibial osteotomies for medial knee osteoarthritis. The open wedge osteotomies were filled with a wedge of osteoconductive beta tricalcium phosphate (beta-TCP) ceramic bone replacement. At the time of removal of the fixation material, core biopsies of the area where the beta-TCP was located were taken at different follow-up periods (6-25 months). beta-TCP resorption, bone ingrowth and bone remodelling were studied. We hypothesized that the incorporation and remodelling process occurs similarly as in animals. Histology showed a good resorption of the beta-TCP with complete incorporation and remodelling into new bone. The different phases as described in animal studies were found. A correlation was found between histological findings and radiological assessment. In conclusion, beta-TCP appeared to be a bone replacement material with optimal biocompatibility, resorption characteristics and bone conduction properties for the clinical use.     

Transport,Uptake, and Metabolism of the Bis(pivaloyloxymethyl)-Ester Prodrug of 9-(2- Phosphonylmethoxyethyl)Adenine in an In Vitro Cell Culture System of the Intestinal Mucosa (Caco-2)

Purpose. To evaluate intestinal transport, uptake and metabolism characteristics of the bis(pivaloyloxymethyl)-ester [bis(POM)-ester] of the antiviral agent 9-(2-phosphonylmethoxyethyl)adenine [PMEA]. Methods. Intestinal transport, uptake and metabolism of bis(POM)-PMEA were studied using an in vitro cell culture system of the intestinal mucosa (Caco-2 monolayers). Concentrations of bis(POM)-PMEA and its metabolites mono(POM)-PMEA and PMEA were determined using a reversed-phase HPLC method. Enzymatic stability of bis(POM)-PMEA was evaluated by incubation with purified liver carboxylesterase, homogenates of Caco-2 cells and scraped pig small intestinal mucosa. Results. The use of bis(POM)-PMEA as a prodrug of PMEA resulted in a significant increase in transport of total PMEA [bis(POM)-PMEA, mono(POM)-PMEA and PMEA] across Caco-2 monolayers. While transepithelial transport of PMEA (500 M) was lower than 0.1% during a 3 hr incubation period, transport of total PMEA after addition of bis(POM)-PMEA (100 M) amounted to 8.8% over the same incubation period. Only 23% of the amount transported appeared as intact bis-ester at the basolateral side, while 33% of this amount was free PMEA and 44% was mono(POM)-PMEA, suggesting susceptibility of the prodrug to chemical and enzymatic degradation. Uptake studies revealed that only negligible amounts of bis(POM)-PMEA (< 0.2%) were present inside the cells. Very high intracellular concentrations of PMEA were found 1.2 mM, after a 3 hr incubation with 50 M bis(POM)-PMEA), which suggests that PMEA was trapped inside the cells probably due to its negative charge. This explains that efflux of PMEA was relatively slow (25% of the intracellular amount in 3 hr). Enzymatic degradation of the prodrug by carboxylesterase was confirmed by incubation of bis(POM)-PMEA with purified enzyme (K_m = 87 M and V_max = 9.5 M/min). Incubation of bis(POM)-PMEA (10 M) with cell homogenate of Caco-2 monolayers and pig small intestinal mucosa produced similar degradation profiles. Conclusions. The use of the bis(POM)-prodrug significantly enhances the intestinal permeability of PMEA. Intracellular trapping of PMEA in the intestinal mucosa may result in slow release of PMEA to the circulation after oral administration of bis(POM)-PMEA.     

Transfer of liposomal drug carriers from the blood to the peritoneal cavity of normal and ascitic tumor-bearing mice

Summary Previously we have demonstrated that the L1210 antitumor activity of liposomal doxorubicin increased significantly as the size of the liposomal carrier was reduced from 1.0 to 0.1 m. It is demonstrated herein that empty and drug-loaded small (0.1-m diameter) liposomes accumulate efficiently into the peritoneal cavity of normal and ascitic L1210 tumor-bearing animals following i.v. administration. In normal mice injected with 100 nm DSPC/chol liposomal doxorubicin (drug-to-lipid ratio of 0.2; wt/wt) approximately 2.8 g drug could be recovered from the peritoneal cavity following peritoneal lavage at 24 h. Although this represents only 0.7% of the injected doxorubicin dose, this level of drug is 2 orders of magnitude greater than that achieved following administration of an equivalent dose of free drug (20 mg/kg). The drug levels achieved within the peritoneal cavity are dependent on the physical characteristics (size, drug-to-lipid ratio and lipid composition) of the liposomes employed. Optimal delivery is obtained employing 100 nm DSPC/chol liposomal doxorubicin, a vesicle system that is known to retain entrapped drug following i.v. administration and exhibits extended circulation lifetimes. Analysis of drug and liposome distribution within the peritoneal cavity of normal mice indicates that as much as 50% of the measured doxorubicin and liposomal lipid is cell-associated. Flow cytometric analysis of the peritoneal cells demonstrated that cell-associated doxorubicin resides almost exclusively within resident peritoneal macrophages. The increased delivery of doxorubicin to the peritoneal cavity of normal mice following i.v. administration of small (0.1-m) liposomal doxorubicin is correlated with a pronounced (>90%) and prolonged (>14-day) suppression of resident peritoneal cells. Liposomal drug accumulation increased dramatically in animals with an established L1210 ascitic tumor. More than 5% of the injected dose was found in the peritoneal cavity of these animals 24 h after treatment with DSPC/chol liposomal doxorubicin as compared with a value of 0.03% of the injected dose achieved with free drug. It is proposed that accumulation of liposomes into the peritoneal cavity of normal and tumor-bearing mice may serve as a useful model for characterizing factors mediating the transfer of liposomes from the vascular compartment to extravascular sites.