scholarly journals Distribution of immunoglobulin G receptors in the small intestine of the young rat.

1980 ◽  
Vol 85 (1) ◽  
pp. 18-32 ◽  
Author(s):  
R Rodewald
Keyword(s):  
Small Intestine ◽  
Immunoglobulin G ◽  
Specific Binding ◽  
Proximal Jejunum ◽  
Luminal Surface ◽  
Surface Receptors ◽  
Receptor Complexes ◽  
Absorptive Cells ◽  
Igg Receptors ◽  
Old Rats

Conjugates of horseradish peroxidase (HRP) and immunoglobulin G (IgG) were used to map the distribution of cell surface receptors that can bind IgG at 0 degrees C within the small intestine of 10-12-d-old rats. Luminal receptors are present only within the duodenum and proximal jejunum. In these locations, receptors are limited to absorptive cells that line the upper portion of individual villi. Near villus tips, receptors are relatively evenly distributed over the entire luminal plasmalemma. In the midregion of villi, receptors are unevenly distributed over the luminal surface. Receptors (a) specifically bind rat and rabbit IgG, (b) recognize the Fc portion of the immunoglobulins, and (c) bind at pH 6.0 but not pH 7.4. To determine whether IgG receptors are confined to the luminal portion of the plasmalemma, intact epithelial cells were isolated from the proximal intestine of 10-12-d-old rats and incubated with HRP conjugates at 0 degree C. The specific binding of rat IgG-HRP to cells at pH 6.0 indicates that IgG receptors, which are functionally similar to those found on the luminal surface, are also present over the entire abluminal surface of absorptive cells. These results are consistent with the transport of IgG to the abluminal plasma membrane in the form of IgG-receptor complexes on the surface of vesicles. Exposure of these complexes to the serosal plasma, which is presumably at pH 7.4, would cause release of IgG from the receptors. To assess possible inward movement of vesicles from the abluminal surface after discharge of IgG, intravenously injected HRP was used as a space-filling tracer in the serosal plasma. HRP could be visualized within the coated and tubular vesicles responsible for transport of IgG in the opposite direction. These vesicles may, therefore, provide a pathway whereby receptors shuttle between the luminal and abluminal surfaces of cells.

scholarly journals Pharmaceutical immunoglobulin G impairs anti-carcinoma activity of oxaliplatin in colon cancer cells

2021 ◽  
Author(s):  
Yuru Shang ◽  
Xianbin Zhang ◽  
Lili Lu ◽  
Ke Jiang ◽  
Mathias Krohn ◽  
...  
Keyword(s):  
Colon Cancer ◽  
Cell Viability ◽  
Cancer Patients ◽  
Cell Lines ◽  
Cancer Cell ◽  
Immunoglobulin G ◽  
Cancer Cell Lines ◽  
Human Igg ◽  
Western Blots ◽  
Igg Receptors

Abstract Background Recent evidence proves that intravenous human immunoglobulin G (IgG) can impair cancer cell viability. However, no study evaluated whether IgG application benefits cancer patients receiving chemotherapeutics. Methods Influence of pharmaceutical-grade human IgG on the viability of a series of patient-derived colon cancer cell lines with and without chemotherapeutic intervention was determined. Cell death was analysed flow cytometrically. In addition, the influence of oxaliplatin and IgG on the ERK1/2-signalling pathway was evaluated by western blots. Results We evaluated the effects of pharmaceutical IgG, such as PRIVIGEN® IgG and Tonglu® IgG, in combination with chemotherapeutics. We did not observe any significant effects of IgG on tumour cell viability directly; however, human IgG significantly impaired the anti-tumoral effects of oxaliplatin. Primary cancer cell lines express IgG receptors and accumulate human IgG intracellularly. Moreover, while oxaliplatin induced the activation of ERK1/2, the pharmaceutical IgG inhibited ERK1/2 activity. Conclusions The present study demonstrates that pharmaceutical IgG, such as PRIVIGEN® IgG and Tonglu® IgG, can impair the anti-carcinoma activity of oxaliplatin. These data strongly suggest that therapeutic IgG as co-medication might have harmful side effects in cancer patients. The clinical significance of these preclinical observations absolutely advises further preclinical, as well as epidemiological and clinical research.

scholarly journals Phosphatidylcholine synthesis in the developing small intestine

1980 ◽  
Vol 186 (2) ◽  
pp. 399-403 ◽  
Author(s):  
P G Holtzapple ◽  
C M Starr ◽  
T Morck
Keyword(s):  
Small Intestine ◽  
Oleic Acid ◽  
Steady State ◽  
Adult Rats ◽  
Acyltransferase Activity ◽  
Acid Incorporation ◽  
Old Rats ◽  
Phosphatidylcholine Synthesis

1. Phosphatidylcholine synthesis in the foetal, newborn and adult small intestine of rats was studied by determination of cytidine diphosphocholine-1,2-diacylglycerocholine phosphotransferase (cholinephosphotransferase) and acyl-CoA-1-acyl-sn-glycerol-3-phosphocholine acyltransferase (lysophosphatidylcholine acyltransferase) activities and the incorporation of [1-14C]oleic acid into phosphatidylcholine. 2. Cholinephosphotransferase activity was low in foetal jejunum and ileum, increased 3-4 fold in the ileum by 6 days of age and by 12 days in the jejunum. Jejunal activity remained constant throughout weaning; ileal activity gradually decreased to values 25% of that of the jejunum. 3. Lysophosphatidylcholine acyltransferase activity was high in foetal jejunum and ileum, decreased 70% immediately after birth in the jejunum and increased to adult values by 12 days of age. Ileal activity decreased by 20% after birth, but decreased more rapidly at weaning to 30% of the activity in jejunum. 4. Initial rates and steady-state incorporation of [1-14C]oleic acid into phosphatidylcholine by jejunal rings of 10 day-old rats exceeded that observed in jejunal rings from adult rats by 2-4-fold. 5. In the postnatal jejunum, neither cholinephosphotransferase and lysophosphatidylcholine acyltransferase activities nor oleic acid incorporation were stimulated by cortisone administration in vivo.

Tachyphylaxis to the vasopressor effects of endothelin in rat aortic rings

1993 ◽  
Vol 264 (2) ◽  
pp. H352-H356 ◽  
Author(s):  
S. M. Hollenberg ◽  
J. H. Shelhamer ◽  
R. E. Cunnion
Keyword(s):  
Endothelial Cells ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Pressor Effect ◽  
Endothelin Receptor ◽  
Surface Receptors ◽  
Receptor Complexes ◽  
High Affinity ◽  
Potent Vasoconstrictor ◽  
Vasoconstrictor Peptide

Endothelin-1 (ET-1), a potent vasoconstrictor peptide released by endothelial cells, binds with high affinity to surface receptors and is highly resistant to dissociation. We observed tachyphylaxis to the pressor effects of a second application of ET-1 in rat aortic rings and investigated the mechanism of this effect. Developed tension increased progressively with doses of ET-1 ranging from 1 to 500 nM (P < 0.001), and tensions with rechallenge were correspondingly decreased (P < 0.001). In response to 500 nM ET-1, tension increased 1,599 +/- 72 (SE) mg/mg ring wt. Rechallenge with 500 nM ET-1 led to contraction of only 33 +/- 40 mg/mg ring wt. Tachyphylaxis was seen up to 6 h after initial challenge. Pretreatment with nicardipine, lidoflazine, nitroglycerin, and sphingosine did not affect tachyphylaxis. Pretreatment with 500 microM dansylcadaverine (an inhibitor of endothelin internalization) markedly inhibited ET-1-induced contraction and also inhibited tachyphylaxis to ET-1. Further studies with radiolabeled ET-1 suggested that subsequent ET-1 binding is markedly decreased after an initial ET-1 challenge. Dansylcadaverine inhibited ET-1 internalization and also inhibited the decreased binding seen with ET-1 rechallenge. Rat aortic rings demonstrate tachyphylaxis to the pressor effect of a second dose of ET-1. The mechanism appears to be related to binding and subsequent internalization of endothelin-receptor complexes. This effect suggests a possible mechanism for sustained decreases in systemic vascular resistance.

scholarly journals Down-Regulation of Cell Surface Receptors Is Modulated by Polar Residues within the Transmembrane Domain

2000 ◽  
Vol 11 (8) ◽  
pp. 2643-2655 ◽  
Author(s):  
Lolita Zaliauskiene ◽  
Sunghyun Kang ◽  
Christie G. Brouillette ◽  
Jacob Lebowitz ◽  
Ramin B. Arani ◽  
...  
Keyword(s):  
Cell Surface ◽  
Transmembrane Domain ◽  
Gradient Centrifugation ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Surface Proteins ◽  
Down Regulation ◽  
Surface Receptors ◽  
Receptor Complexes ◽  
Polar Residues

How recycling receptors are segregated from down-regulated receptors in the endosome is unknown. In previous studies, we demonstrated that substitutions in the transferrin receptor (TR) transmembrane domain (TM) convert the protein from an efficiently recycling receptor to one that is rapidly down regulated. In this study, we demonstrate that the “signal” within the TM necessary and sufficient for down-regulation is Thr11Gln17Thr19 (numbering in TM). Transplantation of these polar residues into the wild-type TR promotes receptor down-regulation that can be demonstrated by changes in protein half-life and in receptor recycling. Surprisingly, this modification dramatically increases the TR internalization rate as well (∼79% increase). Sucrose gradient centrifugation and cross-linking studies reveal that propensity of the receptors to self-associate correlates with down-regulation. Interestingly, a number of cell surface proteins that contain TM polar residues are known to be efficiently down-regulated, whereas recycling receptors for low-density lipoprotein and transferrin conspicuously lack these residues. Our data, therefore, suggest a simple model in which specific residues within the TM sequences dramatically influence the fate of membrane proteins after endocytosis, providing an alternative signal for down-regulation of receptor complexes to the well-characterized cytoplasmic tail targeting signals.

scholarly journals Adenocarcinomas of the Intestine Induced in Syrian Hamsters by N-methyl-N-nitrosourea

1969 ◽  
Vol 6 (5) ◽  
pp. 403-412
Author(s):  
Katherine McD. Herrold
Keyword(s):  
Small Intestine ◽  
Cytological Change ◽  
Histological Changes ◽  
Syrian Hamsters ◽  
Histological Types ◽  
Absorptive Cells ◽  
Cytological Features

The adenocarcinomas of the intestine induced in Syrian hamsters by N-methyl-N-nitrosourea (NMU) were of two histological types, superficial and intestinal. These types had distinctive characteristics regarding pattern, cytological features, secretion of mucus, and mode of growth. The histological changes induced by NMU in the mucosa of the small intestine differed from what has been described in enzootic intestinal adenocarcinoma and proliferative ileitis of Syrian hamsters. NMU produced alteration in the villous architecture and cytological change in the absorptive cells. There was marked shortening of the villi and reduced thickness of the mucosa. The villous absorptive cells were large and cuboidal with centrally placed nuclei.

scholarly journals Regulation of GLUT5 gene expression in rat intestinal mucosa: regional distribution, circadian rhythm, perinatal development and effect of diabetes

1995 ◽  
Vol 309 (1) ◽  
pp. 271-277 ◽  
Author(s):  
A Castelló ◽  
A Gumá ◽  
L Sevilla ◽  
M Furriols ◽  
X Testar ◽  
...  
Keyword(s):  
Gene Expression ◽  
Small Intestine ◽  
Circadian Rhythm ◽  
Intestinal Absorption ◽  
Light Period ◽  
Proximal Jejunum ◽  
Mrna Levels ◽  
Dark Cycle ◽  
Perinatal Development ◽  
Streptozotocin Induced Diabetes

1. GLUT5 gene expression was studied in small intestine under a variety of conditions characterized by altered intestinal absorption of monosaccharides. 2. RNA-blotting studies showed that GLUT5 mRNA was abundantly expressed in rat and rabbit intestine and kidney, but it was not detected in heart or brown adipose tissue. GLUT5 mRNA levels were higher in the upper segments of the small intestine (duodenum and proximal jejunum) than in the lower segments (distal jejunum and ileum). 3. The intestinal expression of GLUT5 mRNA in rat proximal jejunum showed circadian rhythm. A 12-fold increase in GLUT5 mRNA levels was detected at the end of the light cycle and at the beginning of the dark cycle when compared with the early light period. In keeping with this, GLUT5 protein content in brush-border membranes was also increased at the beginning of the dark cycle compared with that in the light period. 4. In streptozotocin-induced diabetes an 80% increase in GLUT5 mRNA levels in mucosa from the proximal jejunum was detected under conditions in which enhanced intestinal absorption of monosaccharides has been reported. 5. The intestinal expression of GLUT5 mRNA showed regulation during perinatal development. Levels of GLUT5 mRNA were low during fetal life, increased progressively during the postnatal period and reached levels comparable with the adult state after weaning. Weaning on to a high-fat diet partially prevented the induction of GLUT5 gene expression. 6. Our results indicate that GLUT5 gene expression is tightly regulated in small intestine. Regulation involves maximal expression in the upper part of the small intestine, circadian rhythm, developmental regulation dependent on the fat and carbohydrate content in the diet at weaning and enhanced expression in streptozotocin-induced diabetes. Furthermore, changes observed in intestinal GLUT5 expression correlate with reported alterations in intestinal absorption of fructose. This suggests a regulatory role for GLUT5 in fructose uptake by absorptive enterocytes.

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