Differential contribution of the three Aph1 genes to gamma-secretase activity in vivo

Gamma-secretase is the protease responsible for amyloid beta peptide release and is needed for Notch, N-Cadherin, and possibly other signaling pathways. The protease complex consists of at least four subunits, i.e., Presenilin, Aph1, Pen2, and Nicastrin. Two different genes encode Aph1A and Aph1B in man. A duplication of Aph1B in rodents has given rise to a third gene, Aph1C. Different mixes of gamma-secretase subunits assemble in at least four human and six rodent complexes but it is not known whether they have different activities in vivo. We report here the inactivation of the three Aph1 genes in mice. Aph1A-/- embryos show a lethal phenotype characterized by angiogenesis defects in the yolk sac, neuronal tube malformations, and mild somitogenesis defects. Aph1B-/- or C-/- or the combined Aph1BC-/- mice (which can be considered as a model for total Aph1B loss in human) survive into adulthood. However, Aph1BC-/- deficiency causes a mild but significant reduction in amyloid beta percursor protein processing in selective regions of the adult brain. We conclude that the biochemical and physiological repercussions of genetically reducing gamma-secretase activity via the different Aph1 components are quite divergent and tissue specific. Our work provides in vivo evidence for the concept that different gamma-secretase complexes may exert different biological functions. In the context of Alzheimer's disease therapy, this implies the theoretical possibility that targeting specific gamma-secretase subunit combinations could yield less toxic drugs than the currently available general inhibitors of gamma-secretase activity.     

Quality control of multidrug resistance assays in adult acute leukemia: correlation between assays for P-glycoprotein expression and activity

We have compared multiple assays for the P-glycoprotein (Pgp/MDR1) phenotype in fresh and thawed adult acute leukemia to validate and quantitate measures for the expression and function of Pgp. The results are related to the Pgp-expressing KB8 and KB8-5 call lines. The most sensitive assay was the measurement of modulation of the rhodamine 123 (R123) fluorescence by 2 micromol/L PSC833, followed by the modulation of the probe calcein-AM. We also found a good intralaboratory and interlaboratory correlation between the values of the R123/PSC833 assay for fresh as well as thawed samples. In addition, the affects of PSC833 on 3H-daunorubicin (DNR) accumulation, DNR fluorescence, and 3H- vincristine accumulation were very similar. The correlation between the DNR/PSC833 and R123/PSC833 test was r = .86 (N = 51). The modulation of drug accumulation by 8 micromol/L verapamil was the some as the PSC833 effect for DNR (117%, N = 21), but was higher for vincristine in every single case (161% v 121%, N = 22; P< .001), indicating additional verapamil effects, not related to Pgp. The correlation of the staining of viable cells for Pgp with the monoclonal antibody MRK16 was r = .77 (N = 52) for the R123/PSC833 functional test and r = .84 (N = 50) for the DNR/PSC833 test. From these results it could be calculated that a maximal increase of the mean DNR accumulation of about 50% can be achieved by blocking Pgp pump activity with PSC833 in leukemic blast samples with the highest mean Pgp expression. Subpopulations of blast calls with higher Pgp activity are likely to be present. Their relevance has to be studied further. The methods outlined here allow the reliable, quantitative monitoring of the Pgp/MDR1 phenotype in leukemias in multicentered, clinical Pgp modulation studies.     

Three-month B vitamin supplementation in pre-school children affects folate status and homocysteine,but not cognitive performance

Background

Suboptimal vitamin B status might affect cognitive performance in early childhood. We tested the hypothesis that short-term supplementation with folic acid and selected B vitamins improves cognitive function in healthy children in a population with relatively low folate status.

Methods

We screened 1,002 kindergarten children for suboptimal folate status by assessing the total urinary para-aminobenzoylglutamate excretion. Two hundred and fifty low ranking subjects were recruited into a double blind, randomized, controlled trial to receive daily a sachet containing 220 μg folic acid, 1.1 mg vitamin B₂, 0.73 mg B₆, 1.2 μg B₁₂ and 130 mg calcium, or calcium only for 3 months. Primary outcomes were changes in verbal IQ, short-term memory and processing speed between baseline and study end. Secondary outcomes were urinary markers of folate and vitamin B₁₂ status, acetyl-para-aminobenzoylglutamate and methylmalonic acid, respectively, and, in a subgroup of 120 participants, blood folate and plasma homocysteine.

Results

Pre- and post-intervention cognitive measurements were completed by 115 children in the intervention and 122 in the control group. Compared to control, median blood folate increased by about 50 % (P for difference, P < 0.0001). Homocysteine decreased by 1.1 μmol/L compared to baseline, no change was seen in the control group (P for difference P < 0.0001) and acetyl-para-aminobenzoylglutamate was 4 nmol/mmol higher compared to control at the end of the intervention (P < 0.0001). We found no relevant differences between the groups for the cognitive measures.

Conclusion

Short-term improvement of folate and homocysteine status in healthy children does not appear to affect cognitive performance.     

Hypertrichosis,pigmentary retinopathy,and facial anomalies: A new syndrome?

We report on a 22-month-old male with congenital hypertrichosis of the face, arms, legs, shoulders, back, and buttocks, abnormal facial appearance, dolichocephaly, and pigmentary retinopathy. Symmetrical hyperpigmentation is present on the sideburn areas of his face, and hyperpigmented streaks are seen on arms and legs. Biopsy of the hyperpigmented skin showed many separate bundles of smooth muscles in the dermis. No relative had hypertrichosis or other birth defects. To our knowledge, the syndrome of facial anomalies, pigmentary retinopathy, and congenital hypertrichosis has not been reported previously. © 1996 Wiley-Liss, Inc.     

A histomorphometric analysis of heavily loaded and non-loaded implants

PURPOSE: To investigate the bone tissue response at the interface of loaded and non-loaded implants used in an orthopedic anchorage system after a continuous, non-axial force application of 5 N over 2 months. MATERIALS AND METHODS: Twenty-nine Br?nemark System implants were placed in the zygomatic arches of 5 dogs. After a healing period of 8 weeks, 20 implants (4 in each dog) were loaded during 8 weeks with a large non-axial orthopedic force application of 5 N. This force was directed between the implants and a maxillary splint to move the maxilla forward. Nine implants were not loaded during this period. At the termination of the experiment, all 29 implants were retrieved for radiographic as well as for histologic analysis. Computer-based histomorphometric quantifications were performed via light microscopy and computer software. Bone-metal contact (BMC), bone surface area (BSA) inside the threads, and the bone mirror area (BMA) of the implants were measured. Statistical comparisons between the loaded and non-loaded implants were carried out. In the group of loaded implants a 2-factor analysis of variance was used. RESULTS: There were no statistically significant differences found in BMC, BSA, and BMA between the loaded and non-loaded implants, both for all the threads and for only the cervical region of the implants. Nor were there statistically significant differences between the non-pressure and pressure sides or for different lengths of the loaded implants. DISCUSSION: The loaded implants maintained the osseointegration achieved during the 8-week healing period. CONCLUSIONS: The results of this study indicate that titanium implants can be used as anchorage for orthopedic force application systems.     

Novel amorphous microporous silica spheres for controlled release applications

A new synthesis route for large spherical particles of amorphous microporous silica (AMS) was developed. These novel spherical porous particles with diameter of around 100 µm and pore diameter smaller than 2 nm were prepared using an oil drop method. Molten ibuprofen was successfully loaded into the AMS pores. In vitro release experiments revealed that ibuprofen was released from the spheres via a slow pore diffusion process lasting up to 14 days. Experimentally determined diffusion coefficients of ibuprofen in the porous spheres were of the order of 10^?15–10^?16 m² s^?1. The present findings reveal the potential of AMS spheres for controlled release of small drug molecules over long time periods. The spherical shape of the AMS particles is advantageous in formulation processes as it provides adequate powder flow properties and reliable release profiles. © 2011 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 100:4295–4301, 2011     

Mothers’ Level of Education and Childbirth Interventions: A Population‐based Study in Flanders,Northern Belgium

Abstract: Background: Interventions to influence the time and way to be born have been a global concern for decades. Yet, limited information is available on what drives these interventions and their variation in frequency among countries, institutions, and practitioners. The objective of this study was to examine to what extent first‐time mothers’ educational achievement contributes to the frequency of childbirth interventions. Methods: Childbirth interventions, including induction of labor, cesarean section, instrumental delivery, and epidural analgesia, registered by the Flemish Study Center for Perinatal Epidemiology for Belgian‐born nulliparous women from 1999 to 2006, were linked to the level of maternal education, recorded by the Belgian civil birth registration. Education was divided into four levels based on the highest diploma attained and adjusted for marital and occupational status. Results: Frequencies of all interventions were inversely related to the level of maternal education. The effect remained after adjustment for birth year, maternal age, marital status, occupation, infant birthweight, gestational age, assisted conception, and type of hospital. Effect sizes between highest and lowest levels of education were relatively small for operative (31% vs 36%) and instrumental vaginal birth (20.7% vs 22.3%) compared with “initiated delivery” (defined as labor induction and prelabor cesarean section; 30.2% vs 40.3%) and epidural analgesia (66.8% vs 78.0%). The educational gradient in initiated delivery occurred at all gestational ages, contributing to lower gestational age and lower birthweight of term infants with decreasing levels of education. Conclusions: In an affluent society with universal and equitable access to maternity care, the more educated women are, the more likely they are to have a spontaneous labor and spontaneous birth without intervention. (BIRTH 38:3 September 2011)