HID-AB2.5-PAS and HID-PAS methods for the histochemical analyses of a variety of carbohydrates

Immunolocalization and functional analysis of Opisthorchis viverrini-M60-like-1 metallopeptidase in animal models

Host mucins have crucial physical roles in preventing the parasitic establishment and maturation, and also in expelling the invading parasites. However, some parasites utilize mucinase enzymes to facilitate the infection. Recently, we have identified a mucinase enzyme of the liver fluke Opisthorchis viverrini, Ov-M60-like-1, which exhibits metallopeptidase activity against bovine submaxillary mucin substrate. Here, we aimed to study the localization of this enzyme in O. viverrini and the bile duct of hamsters using immunohistochemistry and functional analysis by mucin digestion in hamsters and mice tissues. The results showed that Ov-M60-like-1 was detected strongly in the tegument, tegumental cells, vitelline glands and mature eggs with miracidium. Expression in the gut, ovary and testis of the parasite was moderate while parenchyma showed slight colour intensity. In addition, the mucinase was also detected in the host biliary epithelial cells and goblet cells surrounding the worm. The mucinase assay revealed that the Ov-M60-like-1 could digest neutral mucin in the parenchyma, testis and seminal receptacle, but not the mucin in the tegument, tegumental cells and vitelline glands of the worm. The enzyme can also digest mucin in the cholangiocytes and modified the mixture type in the bile duct goblet cells of the infected hamsters, a susceptible host. In contrast, the enzyme was unable to digest neutral, acid and mixture mucin in the bile duct of the mice, a non-susceptible host. These findings indicate that Ov-M60-like-1 may have functions in both housekeeping tasks and host–parasite interactions, especially in modification of host susceptibility.

Chronic stress accelerates the process of gastric precancerous lesions in rats

Background: Gastrointestinal cancers account for 20% of all deaths worldwide. Gastric cancer (GC) patients are susceptible to psychological change, especially depression which is commonly induced by chronic stress. Gastric precancerous lesions (GPL) is an important prodromal stage in the occurrence of gastric cancer. Chronic stress influences the prognosis of GC and may influence the process of GPL as well. Methods: Sixty SD rats were randomly divided into a control group, GPL group, and GPL+CUMS group. In the GPL group, 200μg/mL N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) free drinking method combined with intermittent fasting was applied to establish the GPL animal model. Based on this, we combined the GPL rats with chronic unpredicted mild stress (CUMS) to establish a comprehensive model. We then evaluated their behavior by open field tests and sucrose preference tests. We tested the IL-6, IL-10, TNF-α, Ghrelin, Leptin and Somatostatin (SS) levels in serum and observed the expression of Ghrelin and Gastrokine 2(GKN2) in the gastric mucosa of rats with tumors by immunofluorescence. Results: Our results showed that GPL and GPL+CUMS rats all displayed a significantly decreased total distance and mean velocity traveled in the open field test. The percentages of sucrose preference were significantly decreased in the GPL+CUMS group compared to the control group. In addition, IL-6 and TNF-α were significantly increased in both the GPL and GPL+CUMS groups. Furthermore, the GPL+CUMS group showed significantly increased TNF-α levels in serum compared to the GPL rats. Our results showed that the expression of NF-κB, p53, and BCL-2 were significantly increased while BAX was reduced in the GPL and GPL+CUMS groups. Moreover, Ghrelin and Leptin levels in serum were significantly decreased in the GPL and GPL+CUMS groups. SS levels in serum were significantly increased in the GPL+CUMS group. Additionally, we found that the GPL+CUMS rats with tumors not only had strong expression of GKN2 on the luminal side and the lamina propria of the gastric mucosa and tumor, but also had expression of Ghrelin on the luminal side of the gastric mucosa. The areas that showed strong expression of GKN2 and Ghrelin, are all located around the blood vessels in the tumor. Conclusions: GPL rats under chronic stress would aggravate the conditions of GPL, shorten the process of GPL, and increase the risk of tumorigenesis. In addition, the close monitoring of the mental health of cancer survivors and precancerous lesion patients is suggested to be of great significance in the prevention and treatment of cancer.

Mucosubstances in the porcine gastrointestinal tract: Fixation, staining and quantification

Mucins are of great interest in intestinal research and histochemical methods are often employed to identify them. Since it is in the nature of mucins that they are "hard to hold onto" once they come into contact with water, a frequently used medium in histochemistry, there are a number of challenges that may decrease diagnostic accuracy. As the outcome of methods published for microscopic detection of mucosubstances proved to be unsatisfactory in our hands, the aim was the establishment of a reliable and reproducible protocol. Tissue samples were available from pig feeding experiments. In the present study, we focus on a fixation / staining procedure without making comparisons between differently fed pigs. Several fixation and staining procedures were evaluated for their use in semiautomatic quantification and quality assessment of different mucus fractions simultaneous on one tissue section. Cryostat sectioning, subsequent fixation steps with heat, ethanol and modified Bouin's solution, followed by triple staining with high iron diamine, alcian blue and periodic acid-Schiff turned out to be the best method to identify sulfomucin, sialomucin and neutral mucin simultaneous on one tissue section. This methodology resulted in very good morphology of goblet cells with intact mucin containing vesicles within the cells, which was comparable to ultrastructural electron microscopical observations. Semiautomatic quantification of different mucins was possible. In conclusion, reliable mucus quantification and assessment of mucus quality requires strictly tested procedures. According to our experience, the most important aim after cryosectioning is fast fixation of the mucosubstances, which requires a combination of different fixation steps.

Histological and histochemical investigations of the pharyngeal jaw apparatus of a carp Cirrhinus mrigala

The histological organization and histochemical aspects of the pharyngeal jaw apparatus of the Indian major carp Cirrhinus mrigala are described. The pharyngeal jaw apparatus consists of a lower pharyngeal jaw and a chewing pad. Histochemical analysis reveals that the epithelium covering the lower pharyngeal jaw is mucogenic and is involved in the secretion of different classes of glycoproteins (GPs) including GPs with oxidizable vicinal diols, GPs with O-sulphate esters and GPs with sialic acid residues with and without O-acyl substitution. Characteristically, the epithelium at irregular intervals is differentiated into simple or branched tubular pharyngeal glands, which often extend deep into the sub-epithelial tissues. Copious mucus secretion from pharyngeal glands may be associated with transportation of chewed food particles toward the esophagus. Histochemistry and fluorescence microscopy show that the epithelium covering the chewing pad is keratinized. The keratinized surface of the chewing pad may be considered to serve as an occlusion surface for the lower pharyngeal jaw teeth forming an efficient pharyngeal mill for chewing food materials.

Histochemical analysis of glycoproteins in the secretory cells in the epidermis of the head skin of Indian Major Carp, Labeo rohita

A series of histochemical procedures were employed to localise and characterise glycoprotein (GP) classes produced by the epithelial cells, the type A and the type B mucous goblet cells (MGCs) and the club cells in the epidermis of Labeo rohita. The epithelial cells secreted GPs with oxidizable vicinal diols and GPs with sialic acid residues without O-acyl substitution in low concentrations. The type A MGCs and the type B MGCs, in contrast, produced these GPs in high concentrations. Further, these MGCs produced GPs with O-sulphate esters as well. GPs with O-sulphate esters were produced in high concentration by the type A MGCs and in low concentration by the type B MGCs. The club cells produced GPs with oxidizable vicinal diols in trace amounts. Production of more than one type of GPs suggested a basis for functional discrimination in their role in the mucous secretions at the skin surface. This is considered an adaptation to environment inhabited by the fish and is discussed in relation to their role in lubrication, protection and inhibition of the invasion and proliferation of pathogenic micro-organisms.

Histochemical characterization of glycoproteins in the buccal epithelium of the catfish, Rita rita

Glycoproteins (GPs) elaborated by the buccal epithelium of the catfish, Rita rita, were analysed by a range of histochemical methods. These included methods for the characterization and simultaneous visualization of GPs with oxidizable vicinal diols, with O-acyl sugars, with O-sulphate esters and with sialic acid residues with and without O-acyl substitution at C7, C8 or C9. GPs elaborated at the surface of the buccal epithelium are primarily from two sources, the epithelial cells and the mucous goblet cells. They include GPs with O-sulphate esters, GPs with sialic acid residues without O-acyl substitution and GPs with oxidizable vicinal diols. Different classes of GPs have been associated with specific functions and are discussed in relation to their physiological significance, with special reference to their roles in lubrication, alteration in viscosity, trapping of food particles, buffering of fluids at the epithelial surface, prevention of proteoloytic damage to the epithelium, antimicrobial activity and defence against pathogens. The epithelium shows specialized modifications in the form of the buccal glands. These have been considered to increase the secretory surface that allows profuse secretion of mucus in a very short period of time. The secretions of these glands have been associated with multiple functions similar to those of saliva.