Structural and functional aspects of liver sinusoidal endothelial cell fenestrae: a review

This review provides a detailed overview of the current state of knowledge about the ultrastructure and dynamics of liver sinusoidal endothelial fenestrae. Various aspects of liver sinusoidal endothelial fenestrae regarding their structure, origin, species specificity, dynamics and formation will be explored. In addition, the role of liver sinusoidal endothelial fenestrae in relation to lipoprotein metabolism, fibrosis and cancer will be approached.     

Structures and serology of the O-antigens of Proteus strains classified into serogroup O17 and former serogroup O35

Introduction Bacteria of the genus Proteus are facultative pathogens which commonly cause urinary tract infections. Based on the serological specificity of the O-chain polysaccharide of the lipopolysaccharide (O-polysaccharide, O-antigen), strains of P. mirabilis and P. vulgaris have been classified into 60 serogroups. Studies on the chemical structure and serological specificity of the O-antigens aim at the elucidation of the molecular basis and improvement of the serological classification of these bacteria. Materials and Methods The O-polysaccharide was prepared by acetic acid degradation of the lipopolysaccharide isolated from dried bacterial mass of each strain by hot phenol/water extraction. ¹H- and ¹³C-NMR spectroscopy was used for structural studies. Serological studies were performed with rabbit O-antisera using enzyme immunosorbent assay, passive hemolysis test, and the inhibition of reactions in these assays as well DOC-PAGE and Western blot. Results Four Proteus strains belonging to serogroups O17 and O35 were found to possess similar O-polysaccharide structures, in particular having the same carbohydrate backbone built up of tetrasaccharide repeating units. However, they differ in the presence or absence of additional substituents, such as phosphoethanolamine in P. mirabilis O17 and glucose in P. penneri O17, as well as in the pattern and degree of O-acetylation of various monosaccharide residues. Serological studies also showed close relationships between the O-antigens studied. Conclusions Based on these data it is proposed to reclassify strain P. mirabilis PrK 61/57, formerly representing the O35 serogroup, into the serogroup O17 in the Kauffman-Perch classification system of Proteus.     

Block Copolymers of Methyl Vinyl Ether and Isobutyl Vinyl Ether With Thermo‐Adjustable Amphiphilic Properties

The thermo‐adjustable hydrophilic/hydrophobic properties of AB, ABA and BAB block copolymers in which A is poly(methyl vinyl ether) (PMVE) and B is poly(isobutyl vinyl ether) (PIBVE) have been investigated. The block copolymers were prepared by “living” cationic polymerization using sequential addition of monomers. The polymerizations were carried out with the system acetal/trimethylsilyl iodide as initiator and ZnI₂ as activator. The initiating system based on diethoxyethane leads to AB block copolymers whereas the initiating system based on tetramethoxypropane leads to ABA or BAB triblock copolymers. Well‐defined block copolymers of different composition with controlled molecular weights up to approx. 10 000 have been prepared. When IBVE is added to living PMVE, PIBVE‐blocks form only in the presence of an additional amount of ZnI₂, which is attributed to the fact that part of the ZnI₂ is inactive because of complex formation with PMVE. At room temperature, the combination of hydrophilic (PMVE) and hydrophobic (PIBVE) segments provides the copolymers with surfactant properties. Above the lower critical solution temperature (LCST) of PMVE, situated around 36 °C, the PMVE‐blocks become hydrophobic and the amphiphilic nature of the block copolymers is lost. The corresponding changes in hydrophilic/hydrophobic balance have been evaluated by investigation of the emulsifying properties of the block copolymers for water/decane mixtures as a function of the temperature. Below the LCST, the block copolymers have emulsifying properties similar to or better than those of the commercial PEO‐PPO block copolymers (Pluronic®). Either oil‐in‐water or water‐in‐oil emulsions can be obtained, depending on the polymer architecture and the water/decane volume ratio. The emulsifying properties are strongly reduced or completely lost above 40 °C. Emulsions obtained with a PMVE₃₆‐b‐PIBVE₅₄ block copolymer for a water/decane (v/v) ratio of 85/15 remained stable for more than six months.

50/50 and a 85/15 water/decane w/o emulsion (15 g/l) with the PMVE₃₆‐b‐PIBVE₅₄ block copolymer at 20 °C.     

The Transplantation of hBM-MSCs Increases Bone Neo-Formation and Preserves Hearing Function in the Treatment of Temporal Bone Defects – on the Experience of Two Month Follow Up

Temporal bone reconstruction is a persisting problem following middle ear cholesteatoma surgery. Seeking to advance the clinical transfer of stem cell therapy we attempted the reconstruction of temporal bone using a composite bioartificial graft based on a hydroxyapatite bone scaffold combined with human bone marrow-derived mesenchymal stromal cells (hBM-MSCs). The aim of this study was to evaluate the effect of the combined biomaterial on the healing of postoperative temporal bone defects and the preservation of physiological hearing functions in a guinea pig model. The treatment’s effect could be observed at 1 and 2 months after implantation of the biomaterial, as opposed to the control group. The clinical evaluation of our results included animal survival, clinical signs of an inflammatory response, and exploration of the tympanic bulla. Osteogenesis, angiogenesis, and inflammation were evaluated by histopathological analyses, whereas hBM-MSCs survival was evaluated by immunofluorescence assays. Hearing capacity was evaluated by objective audiometric methods, i.e. auditory brainstem responses and otoacoustic emission. Our study shows that hBM-MSCs, in combination with hydroxyapatite scaffolds, improves the repair of bone defects providing a safe and effective alternative in their treatment following middle ear surgery due to cholesteatoma.     

Once-Weekly GLP-1 Agonists: How Do They Differ from Exenatide and Liraglutide?

Incretin mimetics offer a new modality in diabetes treatment. This modality is based on the effects of the naturally occurring glucoregulatory gut hormone glucagon-like peptide-1 (GLP-1), which counteracts several pathophysiologic traits in type 2 diabetes. GLP-1 receptor agonists with extended half-lives entailing fewer injections and presumably an improved throughout-the-day glycemic control are in clinical development. This article summarizes the physiologic effects of GLP-1; the effects of the already marketed GLP-1 analogues for daily dosing, exenatide and liraglutide; and reviews the presently published data (with emphasis on clinical pharmacokinetics, efficacy, and safety) on GLP-1 agonists, which currently are in development and intended for once-weekly dosing: albiglutide/albugon, CJC-1131, CJC-1134-PC, exenatide once weekly, and taspoglutide.     

PET imaging of fatty acid amide hydrolase in the brain: synthesis and biological evaluation of an 11C-labelled URB597 analogue

IntroductionFatty acid amide hydrolase (FAAH) is part of the endocannabinoid system (ECS) and has been linked to the aetiology of several neurological and neuropsychiatric disorders. So far no useful PET or SPECT tracer for in vivo visualisation of FAAH has been reported. We synthesized and evaluated a carbon-11-labeled URB597 analogue, biphenyl-3-yl [¹¹C]-4-methoxyphenylcarbamate or [¹¹C]-1, as potential FAAH imaging agent.MethodsThe inhibitory activity of 1 was determined in vitro using recombinant FAAH. Radiosynthesis of [¹¹C]-1 was performed by methylation using [¹¹C]-CH₃I, followed by HPLC purification. Biological evaluation was done by biodistribution studies in wild-type and FAAH knock-out mice, and by ex vivo and in vivo metabolite analysis. The influence of URB597 pretreatment on the metabolisation profile was assessed.Results[¹¹C]-1 was obtained in good yields and high radiochemical purity. Biodistribution studies revealed high brain uptake in wild-type and FAAH knock-out mice, but no retention of radioactivity could be demonstrated. Metabolite analysis and URB597 pretreatment confirmed the non-FAAH-mediated metabolisation of [¹¹C]-1. The inhibition mechanism was determined to be reversible. In addition, the inhibition of URB597 appeared slowly reversible.ConclusionsAlthough [¹¹C]-1 inhibits FAAH in vitro and displays high brain uptake, the inhibition mechanism seems to deviate from the proposed carbamylation mechanism. Consequently, it does not covalently bind to FAAH and will not be useful for mapping the enzyme in vivo. However, it represents a potential starting point for the development of in vivo FAAH imaging tools.     

Clinical Assessment of Scapular Positioning in Musicians: An Intertester Reliability Study

Context:

The reliability of the measurement of the distance between the posterior border of the acromion and the wall and the reliability of the modified lateral scapular slide test have not been studied. Overall, the reliability of the clinical tools used to assess scapular positioning has not been studied in musicians.

Objective:

To examine the intertester reliability of scapular observation and 2 clinical tests for the assessment of scapular positioning in musicians.

Design:

Intertester reliability study.

Setting:

University research laboratory.

Patients or Other Participants:

Thirty healthy student musicians at a single university.

Main Outcome Measure(s):

Two assessors performed a standardized observation protocol, the measurement of the distance between the posterior border of the acromion and the wall, and the modified lateral scapular slide test. Each assessor was blinded to the other''s findings.

Results:

The intertester reliability coefficients (κ) for the observation in relaxed position, during unloaded movement, and during loaded movement were 0.41, 0.63, and 0.36, respectively. The κ values for the observation of tilting and winging at rest were 0.48 and 0.42, respectively; during unloaded movement, the κ values were 0.52 and 0.78, respectively; and with a 1-kg load, the κ values were 0.24 and 0.50, respectively. The intraclass correlation coefficient (ICC) of the measurement of the acromial distance was 0.72 in relaxed position and 0.75 with the participant actively retracting both shoulders. The ICCs for the modified lateral scapular slide test varied between 0.63 and 0.58.

Conclusions:

Our results demonstrated that the modified lateral scapular slide test was not a reliable tool to assess scapular positioning in these participants. Our data indicated that scapular observation in the relaxed position and during unloaded abduction in the frontal plane was a reliable assessment tool. The reliability of the measurement of the distance between the posterior border of the acromion and the wall in healthy musicians was moderate.     

The role of genetics and epigenetics in the pathogenesis of gestational diabetes mellitus

Diabetes mellitus (DM) is a heterogeneous group of disorders whose common trait is chronic hyperglycemia. Gestational diabetes mellitus (GDM) is one of the subtypes of DM that manifests during pregnancy. It is believed that 2%–5% of pregnancies worldwide are complicated with GDM, with the prevalence having significantly increased over the last decade. While the pathogenesis of the disease remains largely unknown, GDM is believed to be a result of interactions between genetic, epigenetic, and environmental factors. Linkage and association studies, including those that are genome-wide, have allowed us to identify complex genetic and epigenetic mechanisms that lead to the development of GDM. Multiple common variants in candidate genes such as potassium inwardly rectifying channel subfamily J, member 11 (KCNJ11), glucokinase (GCK), or hepatocyte nuclear factor 1α (HNF1A) have been found to increase the disease risk. In this review, we provide a detailed overview of the current knowledge concerning the influence of genetics and epigenetics on the development of GDM.     

Local environmental factors determine hematopoietic differentiation of neural stem cells

Stem cells exhibit unique properties and hold high therapeutic promise, but factors influencing their differentiation after transplantation need to be recognized and defined for this promise to be fully met. Here, we demonstrate that endogenous colony-forming unit spleen (CFU-S) colonies are not generated in lethally irradiated mice transplanted with neural stem cells obtained from brain tissue of syngeneic donors. We investigated the proportion of transplanted neural stem cells that contributed to hematopoietic reconstitution and compared the distribution of transplanted cells in nonsplenectomized to that of splenectomized mice following sublethal whole-body irradiation. We also used clonogenic assays, colony assays, and histochemical analyses to explore conditions under which transplanted, beta-galactosidase-tagged neural stem cells underwent hematopoietic differentiation. Our results suggest that neural stem cells do undergo extramedullary hematopoiesis, even while no endogenous hematopoietic colonies develop in the spleen. Furthermore, we found that neural stem cells effectively colonized the bone marrow of splectomized recipients. We conclude that the hematopoietic differentiation of neural stem cells is highly dependent on the extramedullary environment. We also conclude that the bone marrow does not provide an environment supportive of hematopoietic differentiation by neural stem cells.