Transmission Of Macromolecules Research Articles

Micro-mechanism of low-density lipoproteins (LDL) transport in multi-layered arterial wall

This paper investigates micro-mechanism of LDL transport numerically in a multi-layer arterial wall. A novel comprehensive 3D model is developed by considering the coupling interactions between vascular layers, and numerical simulations are carried out for a two-layer structure arterial wall. Results displayed the effects of dynamic viscosity on LDL transport. Moreover, we present data demonstrating that endothelial cells have a great blocking effect on the permeation and transmission of macromolecules by the different vascular wall. Furthermore, to verify the reliability and efficiency, a comparison is presented which shows that our numerical results are in good consistency with the experimental data in the literature.

Inclusion Biogenesis, Methods of Isolation and Clinical Application of Human Cellular Exosomes

Exosomes are a heterogenous subpopulation of extracellular vesicles 30–150 nm in range and of endosome-derived origin. We explored the exosome formation through different systems, including the endosomal sorting complex required for transport (ESCRT) and ESCRT-independent system, looking at the mechanisms of release. Different isolation techniques and specificities of exosomes from different tissues and cells are also discussed. Despite more than 30 years of research that followed their definition and indicated their important role in cellular physiology, the exosome biology is still in its infancy with rapidly growing interest. The reasons for the rapid increase in interest with respect to exosome biology is because they provide means of intercellular communication and transmission of macromolecules between cells, with a potential role in the development of diseases. Moreover, they have been investigated as prognostic biomarkers, with a potential for further development as diagnostic tools for neurodegenerative diseases and cancer. The interest grows further with the fact that exosomes were reported as useful vectors for drugs.

Optimization of Crossflow Microfiltration of Disrupted Arthrobacter luteus Cells

Influence of various conditions on crossflow microfiltration of disrupted Arthrobacter luteus cells has been analyzed. Evaluation of permeate flux and transmission of macromolecules through the membrane demonstrates that the 750 kDa MWCO polysulfone membrane is the most efficient. Ionic strength, cell concentration, and pH have the highest influence on the yield of AluI restriction endonuclease. Meanwhile, the flocculation and decreased pH have the largest effect on performance of crossflow microfiltration. Flocculation with polyethyleneimine (PEI) have increased the permeate flux to 45.7 Lh−1m−2 and pH5.5 decreased the flux to 22.2 Lh−1m−2. In conclusion, optimal conditions for crossflow microfiltration of A. luteus cells lysate have been identified.

Intestinal Uptake and Transmission of Macromolecules into the Blood in the Young Guinea Pig

SummaryThe developmental changes in the ability of the small intestinal epithelium to take up and transfer into blood the macromolecules bovine serum albumin (BSA), bovine immunoglobulin G (BIgG), and fluorescein isothiocyanate‐labeled dextran 70,000 (FITC‐dextran) were studied in guinea pigs 0–14 days of age. In addition, in the same animals, the activities of the proteases cathepsin B and D within the intestinal mucosa were measured. Four hours after gavage feeding, 0‐day‐old guinea pigs showed an uptake of the markers into the enterocytes throughout the small intestine. In 2‐day‐old guinea pigs, the markers were only detected in the enterocytes in the distal part. All three macromolecules passed into the blood in these young animals. In 7‐day‐old guinea pigs, no epithelial marker uptake was observed, but low levels of BSA and FITC‐dextran could still be detected in serum. Neither epithelial uptake nor transfer of the markers to the blood could be found in the animals that were 14 days of age. The activity of cathepsin B and D in the intestinal mucosa showed a tendency to increase with age, and for all ages the activity in the distal part was higher than in the proximal part. The results showed that the small intestine in guinea pigs at birth is capable of macromolecular uptake and transfer into the circulation. This ability decreased with age eventually leading to intestinal closure after 1 week. The histological findings implied that intestinal closure was a consequence of a replacement of fetal absorptive cells with adult cells lacking this ability.

Intestinal uptake and transmission of macromolecules into the blood in the young guinea pig.

The developmental changes in the ability of the small intestinal epithelium to take up and transfer into blood the macromolecules bovine serum albumin (BSA), bovine immunoglobulin G (BIgG), and fluorescein isothiocyanate-labeled dextran 70,000 (FITC-dextran) were studied in guinea pigs 0-14 days of age. In addition, in the same animals, the activities of the proteases cathepsin B and D within the intestinal mucosa were measured. Four hours after gavage feeding, 0-day-old guinea pigs showed an uptake of the markers into the enterocytes throughout the small intestine. In 2-day-old guinea pigs, the markers were only detected in the enterocytes in the distal part. All three macromolecules passed into the blood in these young animals. In 7-day-old guinea pigs, no epithelial marker uptake was observed, but low levels of BSA and FITC-dextran could still be detected in serum. Neither epithelial uptake nor transfer of the markers to the blood could be found in the animals that were 14 days of age. The activity of cathepsin B and D in the intestinal mucosa showed a tendency to increase with age, and for all ages the activity in the distal part was higher than in the proximal part. The results showed that the small intestine in guinea pigs at birth is capable of macromolecular uptake and transfer into the circulation. This ability decreased with age eventually leading to intestinal closure after 1 week. The histological findings implied that intestinal closure was a consequence of a replacement of fetal absorptive cells with adult cells lacking this ability.

Immune development in the gastrointestinal tract of the pig

AbstractThe epitheliochorial placenta of the pig does not allow the passage of immunoglobulin to the foetus and thus the young piglet is born without passive immune protection. During the first 36 h of life there is a massive transmission of macromolecules across the intestine, virtually all that are present in the gut may be effectively endocytosed and transmitted into the blood stream. The postnatal transmission of antibody from colostrum during this period provides the young animal with a spectrum of serum antibodies indistinguishable from that of its mother. It is established that evenin uterothe piglet is capable of mounting some response to antigenic challenge. Despite this, the ability of the young animal to respond may be influenced profoundly by the absorption of macromolecules (antibodies and antigens in colostrum and in sow's milk as well as antigens in the farrowing house) during the first hours after birth. These effects range from passive protection from infectious agents during the neonatal period to determining the precise nature of the immune response to antigens during later periods (e.g. at weaning).At birth all cellular components of the immune system are represented but during the first few weeks of life dramatic changes occur in the number and distribution of these cells. Our histological studies have shown that shortly after birth the predominant T lymphocytes in the small intestine are T2+, T4−and T8−; whilst in other organs there are large numbers of conventional T4+and T8+cells. By 1 week of age there is a dramatic increase in the numbers of T4+cells, whilst T8+cells remain low, and only start to increase by week 7. Thus, changes in lymphocyte populations are occurring concurrent with increasing exposure to environmental antigens. The functional capacity of these cells also changes during this period and this process may be particularly affected by early weaning.During the neonatal period an animal is presented with a vast array of antigenic material for the first time. How and when these antigens are presented may profoundly influence the capacity of the immune system to respond to them.

Cathepsin B and D Activities in Intestinal Mucosa during Postnatal Development in Pigs. Relation to Intestinal Uptake and Transmission of Macromolecules

The mucosal activities of cathepsin B and D were assayed in the small intestine of newborn pigs and of pigs 24 h, 6 days and 4-8 weeks old, respectively. Before sacrificing these animals, the intestinal capacity to internalise and further transmit macromolecules into the blood serum was evaluated by feeding a marker solution containing bovine IgG, bovine serum albumin and fluorescein-isothiocyanate-conjugated dextran 70,000 (FITC-dextran). No significant differences in the activities of cathepsin B or D were observed in the mucosa from the various age groups of pigs. The transmission of the marker macromolecules into the blood was higher in the newborn pigs than in older postclosure animals, all of which only had low or undetectable serum marker concentrations. No apparent difference in the uptake of the markers into the intestinal epithelium could be detected between that of the newborn, preclosure pigs and pigs 24 h old. Both groups showed a similar pattern of mucosal fluorescence, indicating that there had been a high uptake of all markers into the epithelium. In the 6-day-old pigs, epithelial uptake was only visible in the distal small intestine, whereas no uptake at all could be found in the animals 4-8 weeks of age. The results suggest that intestinal closure in the pig, i.e. the dramatic decrease in the transfer of macromolecules from the intestinal epithelium in the blood at about 24 h of age, is not due to a decrease in the endocytotic ability of the enterocytes, nor to a higher degradation rate within these cells.(ABSTRACT TRUNCATED AT 250 WORDS)