Search results for "epithelium"

2019

The olfactory epithelium is continuously exposed to exogenous chemicals, including odorants. During the past decade, the enzymes surrounding the olfactory receptors have been shown to make an important contribution to the process of olfaction. Mammalian xenobiotic metabolizing enzymes, such as cytochrome P450, esterases and glutathione transferases (GSTs), have been shown to participate in odorant clearance from the olfactory receptor environment, consequently contributing to the maintenance of sensitivity toward odorants. GSTs have previously been shown to be involved in numerous physiological processes, including detoxification, steroid hormone biosynthesis, and amino acid catabolism. The…

Patterns of expression of trichocytic and epithelial cytokeratins in mammalian tissues

1988

Abstract Cells forming hair and nail material are characterized by the synthesis of members of a particular group of α-keratin polypeptides (trichocytic cytokeratins, “T cytokeratins”) different from epithelial cytokeratins (“E cytokeratins”). As the precursor cells to trichocytes are derived from fetal epidermal keratinocytes expressing only E cytokeratins, we have studied the patterns of expression of both T and E cytokeratins in developing human hair-and nailforming tissues of different fetal stages, by immunocyto-chemistry using antibodies specific for certain T or E cytokeratins and by two-dimensional gel electrophoresis and immunoblotting. In developing hair follicles up to the early …

Ischemia and post-ischemic regeneration of the small intestinal mucosa

1978

After ligation of the vascular arcades of the upper jejunum in rats, the ischemic damage to the intestinal mucosa and its regenerative behavior after ischemia lasting 120 minutes were investigated with histological and enzyme-histochemical methods. During the ischemic injury of the jejunal mucosa, there is rejection of hydropically swollen epithelial cells into the intestinal lumen advancing from the tip to the base of the villi without a previously detectable loss of activity of the enzymes investigated. At the end of ischemia lasting 120 minutes, there is complete destruction of the villi as well as the upper portions of the crypts. After rapid re-epithelialization of the mucosal surface …

Common antigenic determinant on ductular cells of normal pancreas, on mucosal cells of the gastrointestinal tract and on CEA

1990

CEA is widely used as a human tumour marker and was first defined by Gold and Freedman in 1965 as an antigenic component in cancers derived from gastrointestinal tract epithelium. It is a member of a large family of immunologically related glycoproteins that vary in size and tissue distribution. Studies with c-DNA clones for CEA and NCA reveal that this family consist only of a limited number of different proteins with variable glycosylation, due to post-transcriptional modifications. The complete gene family includes about 10 closely related genes. Recently it was published that in contrast to mRNA coding for CEA, mRNA coding for NCA was expressed predominantly in cancerous tissues. A mono…

Effects of Citric Acid on Human Gingival Epithelium

1987

All-trans to 11-cis retinol isomerization in nuclear membrane fraction from bovine retinal pigment epithelium

1991

Abstract Isomerization of all-trans to 11-cis retinol has been studied in a membrane preparation from the nuclear fraction of bovine retinal pigment epithelium. When the nuclear membrane preparation deprived of endogenous retinoids is incubated with 4·5 μ m all-trans-retinol, the mean value calculated for the isomerase activity is 1·32 nmol 11-cis retinol formed hr−1 mg protein−1. Simultaneous formation of all-trans and 11-cis retinyl esters is also observed in the nuclear preparation. When assayed under the same experimental condition, RPE 150 000 g post-nuclear sediment shows about 70% of the isomerase activity found in the nuclear membrane fraction. Treatment of the nuclear membrane frac…

Immunohistochemical localization of the pro-peptide processing enzymes PC1/PC3 and PC2 in the human anal canal.

1997

Abstract HORsch, D., R. Day, N. G. Seidah, E. Weihe and M. K.-H. SchAFer. Immunohistochemical localization of the pro-peptide processing enzymes PC1/PC3 and PC2 in the human anal canal. Peptides 18(5) 755–760, 1997.—The distribution of prohormone/pro-peptide convertases PC1/PC3 and PC2 was investigated in the human anal canal by immunohistochemistry. Both prohormone convertases exhibited region-specific distribution patterns and were observed in neural and neuroendocrine cells and in nonneuroendocrine cellular elements. PC1/PC3 immunoreactivity was present in enteric neurons, subsets of nerve fibers, and neuroendocrine cells, and also in epithelial cells like intestinal stem cells, and a su…

Ocular gelling microspheres: in vitro precorneal retention time and drug permeation through reconstituted corneal epithelium.

2008

Purpose: The model drug norfloxacin (NOR)was encapsulated into trehalose (TRH) and hydroxyethylcellulose(NAT) microspheres to obtain a novel gelling ophthalmic delivery system for prolonged release on corneal tissue. Methods: We assessed NOR release from microspheres, prepared by the emulsion-solvent evaporation method. A new in vitro tear turnover model, including inserts containing reconstituted human corneal epithelium (RHC), was designed to evaluate the TRH/NAT microspheres’ precorneal retention time. Bioadhesive properties of TRH/NAT microspheres were validated by using drug-loaded microspheres prepared with gelatine (GLT) commonly used as reference material in adhesion studies. Result…

Electrofunctional features of the tilted disc syndrome.

1986

The ERG, EOG and VEPs of 15 patients with tilted disc syndrome were studied. The ERG showed abnormal amplitudes in about 1/4 of the eyes and the EOG values were pathological in 3 patients. It is probable that the abnormality of the inferior-nasal portion of the retina and retinal pigment epithelium seen in the tilted disc syndrome causes the changes in the ERG and EOG. Pattern VEPs latency was delayed in most patients. This finding is probably due to the poor focusing of the light in the retina.

A luminal glycoprotein drives dose-dependent diameter expansion of the Drosophila melanogaster hindgut tube

2012

An important step in epithelial organ development is size maturation of the organ lumen to attain correct dimensions. Here we show that the regulated expression of Tenectin (Tnc) is critical to shape the Drosophila melanogaster hindgut tube. Tnc is a secreted protein that fills the embryonic hindgut lumen during tube diameter expansion. Inside the lumen, Tnc contributes to detectable O-Glycans and forms a dense striated matrix. Loss of tnc causes a narrow hindgut tube, while Tnc over-expression drives tube dilation in a dose-dependent manner. Cellular analyses show that luminal accumulation of Tnc causes an increase in inner and outer tube diameter, and cell flattening within the tube wall,…