Hydrogen activation in propene polymerization with MgCl2-supported Ziegler-Natta catalysts: the effect of the external donor

¹³C NMR analysis of relatively low-molecular-weight polypropylenes prepared using the catalyst system MgCl₂/TiCl₄/phthalate ester-AlEt₃-external Lewis base has revealed the presence of up to around 20% butyl (n-Bu) chain ends, indicative of regioirregular (2,1-) monomer insertion followed by chain transfer with hydrogen. The effect of hydrogen on catalyst activity depends on the nature of the external donor, and the results indicate that at least part of the observed increase in catalyst activity in the presence of hydrogen can be ascribed to the regeneration of active species via chain transfer at dormant (2,1-inserted) sites.     

Detection and subtyping of HIV-1 isolates with a panel of characterized monoclonal antibodies to HIV p24gag

A panel of monoclonal antibodies (Mabs) was used to analyze the number and localization of B-cell epitopes on human immunodeficiency virus (HIV) p24gag and the variability of these epitopes in sequential HIV isolates and in isolates from different geographical origin. The specificity of these Mabs was demonstrated by immunoblotting and radioimmunoprecipitation assays. Cross-inhibition experiments indicated the presence of at least five different epitopes on p24. Analysis with p24 recombinant products revealed that three of the Mabs to p24 were directed to epitopes localized on the C-terminal part. Four other Mabs were directed to epitopes localized on the N-terminal half of the protein. Anti-p24 Mabs were used to develop HIV p24 antigen-capture assays. Application of these assays in HIV isolation resulted in more efficient recovery of HIV. Serotyping of HIV-1 isolates with five anti-p24 Mabs demonstrated that 55/65 isolates recovered from Dutch and Belgian individuals, but only 4/9 HIV-1 African isolates, were recognized by all five Mabs. Five of nine Central African HIV-1 isolates were not reactive with at least one of these Mabs. The variability of p24 appeared to be predominantly localized on the N-terminal part of the protein. Lack of expression of antigenic determinants on p24 was shown to be independent of culture conditions. Moreover, an infectious molecular clone was shown to have the same serotype as the corresponding HIV isolate. The serotype of sequential isolates obtained from 17 individuals over a 1 1/2- to 2 1/2-year period did not change, suggesting a limited in vivo p24 variation over time.     

The Roux operation for postgastrectomy syndromes

The aim of this paper is to describe the technique, indications, and results of the Roux operation as used in the treatment of postgastrectomy syndromes. A Roux gastrojejunostomy with a 40-cm Roux limb is the procedure of choice for alkaline reflux gastritis, because it virtually eliminates reflux of bile and pancreatic juice into the stomach. The slow transit through a Roux limb can also be used to good advantage to slow gastric emptying in patients with dumping. Patients with delayed gastric emptying respond to the combination of near-total gastric resection, which removes the atonic gastric remnant and speeds emptying, and Roux-Y gastrojejunostomy, which prevents reflux esophagitis and provides a reservoir for ingesta in the upper gut. After all Roux operations, however, the Roux limb may slow emptying so much that pain, fullness, nausea, and food vomiting result, the so-called Roux stasis syndrome. Prevention of the Roux stasis syndrome with an "uncut" Roux limb and the treatment of the syndrome by using electrical pacing to suppress the ectopic pacemakers that emerge in the limb offer possible new solutions to this vexing problem.     

SOLEIL: single-objective lens inclined light sheet localization microscopy

High-NA light sheet illumination can improve the resolution of single-molecule localization microscopy (SMLM) by reducing the background fluorescence. These approaches currently require custom-made sample holders or additional specialized objectives, which makes the sample mounting or the optical system complex and therefore reduces the usability of these approaches. Here, we developed a single-objective lens-inclined light sheet microscope (SOLEIL) that is capable of 2D and 3D SMLM in thick samples. SOLEIL combines oblique illumination with point spread function PSF engineering to enable dSTORM imaging in a wide variety of samples. SOLEIL is compatible with standard sample holders and off-the-shelve optics and standard high NA objectives. To accomplish optimal optical sectioning we show that there is an ideal oblique angle and sheet thickness. Furthermore, to show what optical sectioning delivers for SMLM we benchmark SOLEIL against widefield and HILO microscopy with several biological samples. SOLEIL delivers in 15 μm thick Caco2-BBE cells a 374% higher intensity to background ratio and a 54% improvement in the estimated CRLB compared to widefield illumination, and a 184% higher intensity to background ratio and a 20% improvement in the estimated CRLB compared to HILO illumination.     

Social participation and psychosocial outcomes of young adults with chronic physical conditions: Comparing recipients and non-recipients of disability benefits

Background

Little is known about any differences between young people with chronic physical conditions who do and do not apply for disability benefits in young adulthood for providing insights for future policy and rehabilitation care.

Influence of High and Low Autonomy-Supportive Climates on Physical Activity in Children with and without Developmental Disability

The aim of this study was to compare the influence of two different instructional climates on the accumulation of moderate-to-vigorous physical activity (MVPA) during a fully-inclusive adapted recreational physical activity program. A total of 32 children (18 typically-developing (TD), and 14 with developmental disabilities (DD) ranging in ages from 5 to 9 years, participated in six, 60-min adapted recreational sessions. Of those six sessions, three incorporated an autonomy-supportive climate (high autonomy), and three incorporated direct instruction (low autonomy). MVPA was measured using accelerometers. A repeated measures ANOVA was conducted to determine significant differences in MVPA between group (TD/DD), climate (autonomy/direct), and a group x climate interaction. Significant group and climate main effects were observed (p?=?0.002 and 0.014, respectively). However, there was not a significant group x climate interaction (p?=?0.313). These results suggest that although the group of children with disabilities spent less time in MVPA compared to their typically-developing peers, all participants spent more time in MVPA for the autonomy-supportive climate compared to the low-autonomous climate. This study is the first to quantitatively assess the efficacy of a fully-inclusive autonomy-supportive climate on physical activity levels in children with and without developmental disabilities.     

Normal telomere lengths in naive and memory CD4+ T cells in HIV type 1 infection: a mathematical interpretation.

To study CD4+ T cell productivity during HIV-1 infection, CD4+ T cell telomere lengths were measured. Cross-sectional and longitudinal analysis of HIV-1-infected individuals with CD4+ T cells counts >300 cells/mm3 showed normal average telomeric restriction fragment (TRF) length and normal shortening rates of CD45RA+ naive and CD45RO+ memory CD4+ T cells. These TRF data were interpreted in terms of CD4+ T cell production by means of a mathematical model. This model resolves previous criticisms arguing that the normal TRF length of CD4+ T cells in HIV-1 clinical latency is due to the killing of dividing CD4+ T cells by the virus. Only an increased priming rate of naive CD4+ T cells to become memory cells may elongate the average TRF length of memory CD4+ T cells, and may therefore mask the shortening effect of increased turnover in the CD4+ memory T cell compartment. The data are more compatible with the notion that during HIV-1 clinical latency the turnover of CD4+ T cells is not markedly increased, however, and that HIV-related interference with renewal from progenitors plays a role in CD4+ T cell depletion. In such a "limited renewal" scenario disease progression is no longer a consequence of markedly increased CD4+ T cell production.     

T cells in patients with chronic Tγ lymphocytosis: Morphology,cytochemistry, ultrastructure and immunological characteristics

Summary We have studied the morphology and cytochemistry in relation to the immunological phenotyping and functional properties of T cells from eight patients with chronic T lymphocytosis. At the light microscopic level the morphology of the patients' lymphocytes was similar to that described for large granular lymphocytes. Ultrastructurally, a division into two groups could be made on differences in the amount of cytoplasm and the location and the more irregular form of the nuclei. The lymphocytes of one group (five patients) had in common the phenotype Fc+, T3+, T4–, T8+, Ia–, M1– and demonstrated (with the exception of one patient) the same functions: presence of K-cell activity, absence of NK, helper and suppressor cell activities. In the other group (three patients), the lymphocytes of one patient showed the same phenotype and functions as those indicated above. The other two patients both lacked the T8 antigen on their lymphocytes but were different with regard to other surface markers. In addition, their cells were functionally identical: both demonstrated NK- and K-cell activity. Thus in this group of eight patients with chronic T lymphocytosis, the immunological and functional subdivision paralleled in part a morphological division at the ultrastructural level.     

Infection resistance of degradable versus non-degradable biomaterials: An assessment of the potential mechanisms

Extended life expectancy and medical development has led to an increased reliance on biomaterial implants and devices to support or restore human anatomy and function. However, the presence of an implanted biomaterial results in an increased susceptibility to infection. Due to the severity of the potential outcomes of biomaterial-associated infection, different strategies have been employed to reduce the infection risk. Interestingly, degradable biological materials demonstrate increased resistance to bacterial infection compared to non-degradable synthetic biomaterials. Current knowledge about the specific mechanisms of how degradable biological materials are afforded increased resistance to infection is limited. Therefore, in this paper a number of hypotheses to explain the decreased infection risk associated with the use of degradable versus non-degradable biomaterials are evaluated and discussed with reference to the present state of knowledge.