Acyltransferase activities in the yolk sac membrane of the chick embryo

The activities of some enzymes of glycerolipid synthesis and fatty acid oxidation were measured in subcellular fractions of the yolk sac membrane (YSM), an extra-embryonic tissue that mediates the transfer of lipid from the yolk to the circulation of the chick embryo. The activities of monoacylglycerol acyltransferase and carnitine palmitoyl transferase-1 in the YSM (respectively, 284.8±13.2 nmol/min/mg microsomal protein and 145.6±9.1 nmol/min/mg mitochondrial protein; mean ±SE; n=4) at day 12 of development appear to be the highest yet reported for any animal tissue. Also, the carnitine palmitoyl transferase-1 of the YSM was very insensitive to inhibition by malonyl CoA. The maximal activities of glycerol-3-phosphate acyltransferase and diacylglycerol acyltransferase in the YSM (respectively, 26.7±2.2 and 36.1±2.1 nmol/min/mg microsomal protein) were also high compared with the reported values for various animal tissues. The very high enzymic capacity for glycerolipid synthesis supports the hypothesis that the yolk-derived lipids are subjected to hydrolysis followed by reesterification during transit across the YSM. The monoacylglycerol pathway appears to be the main route for glycerolipid resynthesis in the YSM. The results also suggest that the YSM has the capacity to perform simultaneously β-oxidation at a high rate in order to provide energy for the lipid transfer process.     

Advances in Characterization of Non-Rare-Earth Permanent Magnets: Exploring Commercial Alnico Grades 5–7 and 9

The magnetic domain structure of commercial alnico grades 5–7 and 9 was investigated using a magneto-optical Kerr effect (MOKE) to gain an understanding of their coercivity mechanisms at the micron to millimeter scale. In alnico 5–7, the magnetic domain structure exhibits stripes of alternating high and low induction. Magnetic domains easily cross grain boundaries if neighboring grains have a similar tilt and rotation of their crystallographic axes relative to the magnet body. In contrast for alnico 9, stripe-like magnetic domains are not observed regularly throughout the transverse section; rather, discrete localization of high- and low-induction stripe features are observed. In higher magnification MOKE experiments, i.e., ~100 μm, a zigzag-shaped magnetic domain structure was observed in both alnico 5–7 and 9. The zigzag features are four to five times smaller in size than an average grain of alnico 5–7, implying a pinning mechanism that is caused by structural elements within the grains. Discontinuous and reversible motion on a length scale of a few microns was observed for the zigzag-shaped domains for incremental changes in the applied field of ~10 Oe. Complimentary magnetic force microscopy measurements show that there are domain structures on an even smaller scale, i.e., 2 μm to 100 μm.     

Biochemical Investigation of the Interaction of pICln,RioK1 and COPR5 with the PRMT5–MEP50 Complex

The PRMT5–MEP50 methyltransferase complex plays a key role in various cancers and is regulated by different protein–protein interactions. Several proteins have been reported to act as adaptor proteins that recruit substrate proteins to the active site of PRMT5 for the methylation of arginine residues. To define the interaction between these adaptor proteins and PRMT5, we employed peptide truncation and mutation studies and prepared truncated protein constructs. We report the characterisation of the interface between the TIM barrel of PRMT5 and the adaptor proteins pICln, RioK1 and COPR5, and identify the consensus amino acid sequence GQF[D/E]DA[E/D] involved in binding. Protein crystallography revealed that the RioK1 derived peptide interacts with a novel PPI site.     

Extracellular Vesicles as a Therapeutic Tool for Kidney Disease: Current Advances and Perspectives

Extracellular vesicles (EVs) have been described as important mediators of cell communication, regulating several physiological processes, including tissue recovery and regeneration. In the kidneys, EVs derived from stem cells have been shown to support tissue recovery in diverse disease models and have been considered an interesting alternative to cell therapy. For this purpose, however, several challenges remain to be overcome, such as the requirement of a high number of EVs for human therapy and the need for optimization of techniques for their isolation and characterization. Moreover, the kidney’s complexity and the pathological process to be treated require that EVs present a heterogeneous group of molecules to be delivered. In this review, we discuss the recent advances in the use of EVs as a therapeutic tool for kidney diseases. Moreover, we give an overview of the new technologies applied to improve EVs’ efficacy, such as novel methods of EV production and isolation by means of bioreactors and microfluidics, bioengineering the EV content and the use of alternative cell sources, including kidney organoids, to support their transfer to clinical applications.     

SUPERCRITICAL EXTRACTION OF ISRAELI MISHOR ROTEM OIL SHALE 1. BATCH EXTRACTION WITH TOLUENE

ABSTRACT

Recovery of organic material from Israeli Mishor Rotem oil shale with toluene under supercritical conditions was investigated. The rate of solubilization, change of structural aspects and molecular weights of solubilized products with time were investigated. Experiments to recover organic material from shale were performed in a stainless steel high pressure autoclave. Shale Sample was charged in a sintered glass crucible suspended from the cap of the autoclave; toluene was the solvent in all experiments. Solvent/shale ratio was 20; experimental temperature was 34O^°C. The gaseous products were analyzed by gas chromatography. Molecular weights of the organic material recovered was measured by gel permeation chromatography technique. FTIR spectra of the organic material recovered and fractions isolated by extractive and chromatographical methods were measured. The amount of kerogen remaining in the spent shale was determined by oxidative derivative thermal gravimetry. A steady state in the production of solubles was reached within 60 minutes at 340^°C with a yield of 60 percent. After this time no further amounts of organic material was recovered. The molecular weights of the recovered organic material decreased at extended times after the steady state was reached. It appeared that the structure of the organic material recovered remained unchanged until the steady state condition is reached whereupon some structural changes occurred. At extended times the organic material was converted into more aromatic and less hydroxyl containing structures of lower molecular weight. The organic material recovered upon reaching steady state was fractionated into 63 percent oils (pentane solubles) and 32 percent asphaltenes (toluene solubles). The oile contained aliphatics and monoaromatic structures and the asphaltenes contained polyaromatic polar structures. Gases which constituted 4 percent of the initial kerogen were produced during the heating period to 340^°C. The amount of carbon monoxide produced remained constant and amounts of hydrogen, carbon dioxide and methane decreased after supercritical conditions were attained.     

Triacs in Reversible Regenerative DC Motor Drives

This paper presents a triac converter which can replace two thyristor bridges normally used for regenerative dc motor drives. The most important characteristics of the triac are outlined and specific problems are discussed. Performance specifications for the control electronics are given. An experimental drive is presented and some run measurements are shown.     

Fiber Capacity Limits With Optimized Ring Constellations

In this letter, we calculate theoretical limits to fiber-optic transport capacity under the constraint of requiring the use of concentric multiring modulation alphabets. Subject to these conditions, we vary ring amplitude ratios and occupation probabilities to determine the capacity-optimized ring constellations. The technique used for fiber transmission calculations accurately captures all fiber nonlinear effects, with the accuracy limited by the noise and signal statistical properties only.     

Gallbladder diverticulum: a case report and review of the literature

BACKGROUND: The clinical significance of the 14 and 6 positive spikes (PS) electroencephalographic (EEG) phenomenon is not well established. This study was performed to provide further data regarding the clinical correlates of the PS, particularly attention-deficit/hyperactivity and somatic symptoms. METHODS: Diagnostic information gathered through structured interviews was compared among four groups of psychiatric inpatients aged 4-17 years who underwent an EEG examination over a 2-year period. Groups consisted of patients with: 1) 14 and 6 PS (n = 25); 2) epileptic discharges (n = 29); 3) slow-wave abnormalities (n = 23); and 4) a normal EEG group age and sex matched to the 14 and 6 PS group (n = 25). RESULTS: Attention-deficit hyperactivity disorder (ADHD) symptoms were significantly more frequent in the PS group (chi 2 = 2.96, p < .05) compared to the other three groups combined. Although somatic symptoms were not increased in the 14 and 6 PS group, anxiety symptoms tended to occur more in this group (chi 2 = 3.50, p < .06). CONCLUSIONS: The PS profile appears associated with ADHD symptoms. Possible treatment implications of this finding (e.g., use of anticonvulsants in ADHD patients with PS) need to be explored.