Melanization of Bomirski hamster amelanotic melanoma cells (Ab line) depends on the type of culture medium

Introduction. The effect of melanogenesis intensity on melanoma biology remains an open question, and the biological differences between melanotic and amelanotic melanoma cells have not yet been satisfactorily documented. As a result, the melanization of melanoma cells in in vitro cultures is not considered among experimental procedures. The aim of this study was to investigate the effect of the medium used to culture Bomirski amelanotic Ab melanoma cells on the melanogenesis process.Material and methods. Amelanotic melanoma cells (Ab) were cultured in two media recommended for in vitro melanoma cell cultures, RPMI and DMEM. The melanization was evaluated by determining the melanin and tyrosinase presence in the cells using spectrophotometrical and western blot methods, respectively. Changes in Ab melanoma cells’ ultrastructure were determined using electron microscopy (EM).Results. The medium with higher level of tyrosine (DMEM) induced significant melanization of amelanoticmelanoma cells (Ab) after only 24 h, while the RPMI medium, with a lower level of tyrosine, weakly affected melanin production. Melanization of Ab cells was paralleled by an increase in the amount of tyrosinase protein. Induced melanization was easily observed on EM-micrographs in the form of newly formed melanosomes containing melanin pigment. Melanosomes at stages from one (I) to four (IV) were observed.Conclusions. Culture medium has an important effect on the in vitro biology of amelanotic melanoma cells, since it can affect the rate of cellular melanization. The appropriate medium should be carefully selected, taking into account the known biology of the melanoma cells being used

Ultrastructural characteristics of myenteric plexus in patients with colorectal cancer

Introduction. It have been found previously that colorectal cancer (CRC) is accompanied by atrophy of myenteric plexuses (MPs) localized close to the tumor. The aim of the study was to compare ultrastructure of MPs localized in the unchanged part of the colon wall distant to CRC tumor with the ultrastructure of MPs in the vicinity of CRC tumor. Material and methods. The present study was conducted using post-operative material derived from 11 patients with CRC. Samples of colon wall were taken from the margin of cancer invasion and from a macroscopically unchanged segment of the large intestine, immediately fixed and processed according to the standard protocol for transmission electron microscopy studies. Results. In the MPs localized in the control part of colon wall the presence of numerous unmyelinated axons and cell bodies of neurons, interstitial cells of Cajal and enteroglial cells were observed. As compared to control samples, in the MPs located close to the tumor invasion, expansion of the extracellular matrix and myelin-like structures accompanying some nerve fibers were found. The appearance of mast and plasma cells was observed within MPs in the vicinity of CRC tumor. Sporadically, apoptotic cells were present inside the MPs. Conclusions. The presence of myelin-like structures and apoptotic cells within MPs located close to tumor invasion suggests that atrophy of MPs may be caused by factors released from CRC tumor

Morphological alterations in the jejunal mucosa of aged rats and the possible protective role of green tea

Introduction. Gastrointestinal disorders become more prevalent with ageing. This study is aimed to describe morphological changes that occur in the jejunal mucosa of male albino rats as a result of ageing and the protec­tive effect of green tea (GT) extract. Material and methods. The experiment was performed on sixty rats: thirty young-adult (6-month old, body mass 200–220 g) and thirty old (24-month-old, body mass 220–260 g) animals. Each group was further divided into two subgroups (n = 15 each): control rats and GT-treated rats that received 1.5 mL (300 mg/kg/day) of GT extract for 14 weeks by oral gavage. Sections of the jejunum were stained with hematoxylin and eosin, periodic acid Schiff, toluidine blue and Mallory trichrome methods. The presence of proliferating cell nuclear antigen (PCNA)- and CD68-positive cells was evaluated by immunohistochemical staining. Ultrathin sections were prepared and examined by a transmission electron microscope (TEM). Results. Jejunal sections of the old control rats showed distortion of submucosa and attenuated muscularis externa with decreased height of intestinal villi. The villi also showed partial loss of acidophilic brush border with wide spaces between enterocytes. Swollen, short, blunt or broad villi with abundant mononuclear cell infiltration of lamina propria and congested blood vessels were evident both by light and electron microscopy. The number of PCNA- and CD68-positive cells in jejunal mucosa of old rats was higher than in young rats. The activity of glutathione peroxidase (GPX) and total antioxidant capacity (TAC) in the mucosa of old control rats were lower, whereas malondialdehyde (MDA) levels were higher in the jejunal homogenates of old rats as compared to young control rats. Administration of GT extract protected the jejunal mucosa from age-related changes by restoring its histological structure. The treatment of old rats with GT extract significantly decreased MDA levels in the jejunum and increased TAC and GPX activity. Conclusions. The age-related changes of the morphology of rat jejunum could be ameliorated by prolonged supplementation of the green tea extract

Mast cells and their role in pathogenesis of selected skin diseases

Mastocyty, powstające w komórkach hematopoetycznych szpiku kostnego, uwalniają wiele substancji biologicznie czynnych (cytokiny, chemokiny, czynniki wzrostu, neuropeptydy oraz enzymy proteolityczne). Na powierzchni mastocytów znajduje się wiele receptorów determinujących ich funkcje oraz umożliwiających ich interakcje z komórkami układu immunologicznego i neuroendokrynnego skóry. W mastocytozie dochodzi do klonalnej proliferacji MCs, które gromadzą się w tkankach, przede wszystkim w skórze i w szpiku kostnym. W ciężkich postaciach układowych choroby nacieczenie narządów prowadzi do upośledzenia ich funkcji. U chorych zarówno na skórną, jak i układową postać mastocytozy dochodzi do rozwoju objawów zależnych od mediatorów uwalnianych przez mastocyty w procesie degranulacji. W atopowym zapaleniu skóry MCs biorą udział w reakcji nadwrażliwości typu I, promują różnicowanie się limfocytów w kierunku Th2 lub Th1, wydzielają mediatory biorące udział w patogenezie świądu, pobudzają chemotaksję limfocytów i komórek dendrytycznych do skóry oraz przyczyniają się do rozwoju przewlekłego stanu zapalnego skóry. W łuszczycy w obrębie zmian skórnych obserwuje się zwiększoną liczbę MCs, które wydzielają cytokiny prozapalne, stymulują migrację neutrofilów, monocytów i limfocytów do skóry oraz wydzielają mediatory indukujące świąd.Mast cells derived from bone marrow hematopoetic stem cells, have the ability to release multiple biologically active substances (such as cytokines, chemokines, growth factors, neuropeptides, and proteolytic enzymes). On the surface of mast cells, there are numerous receptors that determine the function of these cells and enable them to interact with the cells of the immune system and the neuroendocrine system of the skin. In mastocytosis, there is a clonal proliferation of mast cells which accumulate in various tissues, particularly in the skin and the bone marrow. In severe forms of systemic disease infiltration of organs leads to an impairment of their function. Both patients with cutaneous and systemic mastocytosis suffer from mast cell mediator-related symptoms. In atopic dermatitis MCs are involved in type I hypersensitivity reactions, promote the differentiation of cells towards Th2 or Th1, secrete mediators involved in the pathogenesis of pruritus, stimulate chemotaxis of lymphocytes and dendritic cells into the skin and contribute to the development of chronic inflammation of the skin. In psoriasis an increased number of MCs was found in skin lesions. Moreover, these cells secrete numerous proinflammatory cytokines, stimulate migration of neutrophils, monocytes and lymphocytes into the skin and secrete mediators which induce itching

Short-term fenofibrate treatment improves ultrastructure of hepatocytes of old rats

Introduction. Fenofibrate (FN) is a hypolipemic drug used for the treatment of mixed dyslipidemia. Since in our previous study FN administration to young and old rats adversely affected the serum activity of liver marker enzymes, we decided to examine the effects of FN on liver ultrastructure of young and old animals. Material and methods. Young and old rats were fed standard rodent chow supplemented with 0.1% FN for 30 days. Liver samples obtained from animals under full anesthesia were processed by routine methods to obtain ultrathin and histological sections for the examination by light microscopy (LM) and transmission electron microscopy (TEM). Furthermore, liver lysates were analyzed by Western blotting for the expression of the autophagy-related proteins LC3A/B and beclin 1. Results. The ultrastructure of hepatocytes in both age groups was well-preserved, with the presence of abundant mitochondria, numerous peroxisomes and lysosomes, glycogen stored in the form of rosettes, and occasionally autolysosomes. However, hepatocytes of old control rats contained less mitochondria and peroxisomes, and more lipid droplets than cells of young animals. The effects of FN on liver ultrastructure were age-depended. FN increased the relative number of mitochondria and peroxisomes in the hepatocytes of old, and did not affect their number in young rats. Moreover, FN decreased and increased the relative number of lipid droplets in the hepatocytes of old and young rats, respectively. At the LM level, Oil Red O staining revealed smaller and larger lipid droplets within hepatocytes and non-parenchymal liver cells. In the livers of young and old rats lipid droplets were distributed mainly in the periportal zones of hepatic lobules. Morphometric analysis confirmed that livers of control old rats contained more lipid-stainable areas than those of young ones; however, no effect of FN was observed either in young or old rats. Despite larger size of autolysosomes and autophagic vacuoles in hepatocytes of old rats, the expression of autophagy-related proteins did not differ in the livers of control and fenofibrate-treated young and old animals. Conclusions. The results of our study suggest that fenofibrate, apart from its hypolipemic action, may have beneficial effect on the energy metabolism in the liver of old individuals by increasing the number of mitochondria and peroxisomes in hepatocytes

Characterization of the Three New Kayviruses and Their Lytic Activity Against Multidrug-Resistant Staphylococcus aureus

The development of antimicrobial resistance has become a global concern. One approach to overcome the problem of drug resistance is the application of bacteriophages. This study aimed at characterizing three phages isolated from sewage, which show lytic activity against clinical isolates of multidrug-resistant Staphylococcus aureus. Morphology, genetics and biological properties, including host range, adsorption rate, latent time, phage burst size and lysis profiles, were studied in all three phages. As analyzed by transmission electron microscopy (TEM), phages vB_SauM-A, vB_SauM-C, vB_SauM-D have a myovirion morphology. One of the tested phages, vB_SauM-A, has relatively rapid adsorption (86% in 17.5 min), short latent period (25 min) and extremely large burst size (~500 plaque-forming units (PFU) per infected cell). The genomic analysis revealed that vB_SauM-A, vB_SauM-C, vB_SauM-D possess large genomes (vB_SauM-A 139,031 bp, vB_SauM-C 140,086 bp, vB_SauM-D 139,088 bp) with low G+C content (~30.4%) and are very closely related to the phage K (95–97% similarity). The isolated bacteriophages demonstrate broad host range against MDR S. aureus strains, high lytic activity corresponding to strictly virulent life cycle, suggesting their potential to treat S. aureus infections