[Determination of mono-, di- and triglycerides using HPLC]

The determination of monoglycerides, diglycerides and triglycerides in the normal phase system: Separon SGX-CN (silica gel with phase-bonded cyanoethyl) and mobile phase hexane-isopropanol-formic acid by HPLC with refractometric detection, is described. It was found that the separation was according to the molecular mass of glycerides, i.e. in groups. This was demonstrated with palmitic, oleic and linoleic acids. The diglycerides and especially monoglycerides of olive and sunflower oils were partly separated according to the ECN1 values of the glycerides. The response factors related to triglycerides were estimated for the glycerides of the fatty acids and oils mentioned above. The value of response factors depends on the number of double bonds of the fatty acids.

Effect of a sudden and a slow concentration increase in plasma urea on its concentration in some tissues of the dog and rat

The urea concentration in the renal cortex ([RC]) of pentobarbital-anaesthetized dogs was 5.71 times higher than the plasma concentration ([P]); the liver ([L]) and the skeletal muscle ([SM]) concentrations were the same as ([P]). Rapid infusion of 20% urea (1 g/kg b.w. within 1 min) was followed by a sudden increase in [P]; [RC] and [L] rose to values nonsignificantly different from [P] and remained non-significantly different for the whole 4 hours of the experiment; at the end, [P] was still about 10 times higher than before infusion. Surprisingly, [SM] 2 and 6 min after infusion was significantly lower than [P]; later they were the same. The experiment thus does not testify to the existence of active transport of urea in the RC. The permeability of the skeletal muscle membrane for urea is lower than that of the RC and liver. Chronic uraemia was induced in rats by transplanting the trigonum vesicae into the peritoneal cavity. In addition to the chemical determination of urea, 14C-urea (marked*) was also measured. [RC]/[P] and [RC*]/[P*] fell as [P] rose; [L], [L*] [SM] and [SM*] never differed from [P] or [P*]. Fluid [PF] collected in the peritoneal cavity had the same chemically determined and radioactive urea concentration as P, but it was hypoosmolar and had a lower [Na+] than P. These experiments likewise did not testify to active urea transport in the RC. It is not clear what caused the osmolarity and sodium gradient between the PF and P, but the peritoneal wall definitely did not act as a simple dialyzing membrane.

Effect of Mercurascan on sodium transport in frog skin and bladder

The authors studied the effect of Mercurascan (MSC) (a hydroxy- mercury derivative of fluorescein) on electrical parameters, namely potential difference (P.D.) and short circuit current (S.C.C.) of frog skin and on the ability of frog bladder tissue to accumulate sodium ions in experiments in vitro. It was found that MSC, in 10(-4) mol/l concentration, reduced the S.C.C., after a brief initial increase, to 5% of the original value and that the P.D. fell steadily right from the outset. In 10(-5) mol/l concentration it raised the S.C.C. by 60% and the increase lasted several hours. The P.D. was unaffected. In 10(-7) and 10(-6) mol/l concentration MSC had no effect on the NA+ content of a nonpolarized frog bladder tissue preparation, but a 10(-5) nol/l concentration sharply reduced it. The effect of MSC on membrane Na+--K+ ATPase, i.e. on the energy metabolism of cellular tissue, is discussed with reference to these results.

The role of histology in tissue engineering: Significance of complex morphological characterization of decellularized foreskin scaffolds

Decellularization is a technique of cell removal that prepares vacant extracellular matrices (ECMs), which can be reseeded with patient-specific cells and used in regenerative medicine. Histological methods are vital for protocol standardization and efficacy assessment, which are necessary for preparing such bioscaffolds. Foreskins from male subjects (n=20) aged three to fifteen years were harvested and decellularized using detergent-based and enzyme-based protocols. To acquire a standardized protocol that would provide the optimal balance between effective cell removal and ECM preservation, a total of seven protocols were evaluated using the most basic formalin-fixed paraffin-embedded (FFPE) tissue blocks, which were sectioned and stained with HE, Masson's blue trichrome and orcein. After achieving the optimal result, we further morphologically characterized the scaffolds using scanning electron microscopy (SEM) and immunohistochemical (IHC) detection of fibronectin and collagen IV. Histology proved to be a quick, relatively easy, and cheap method to achieve protocol standardization and assess decellularization efficacy and ECM preservation. Morphological analysis via normal histology, SEM, and IHC showed that both definitive protocols are effective in cell removal but, at the same time, don't compromise the structural integrity of the ECM. Morphological characterization of foreskin-derived bioscaffolds via normal histology, IHC, and SEM is irreplaceable for standardizing decellularization protocols, assessing the efficacy of cell removal, and evaluating ECM preservation.

Exploring the black box of human reproduction: endometrial organoids and assembloids - generation, implantation modeling, and future clinical perspectives

One of the critical processes in human reproduction that is still poorly understood is implantation. The implantation of an early human embryo is considered a significant limitation of successful pregnancy. Therefore, researchers are trying to develop an ideal model of endometrium in vitro that can mimic the endometrial micro-environment in vivo as much as possible. The ultimate goal of endometrial modeling is to study the molecular interactions at the embryo-maternal interface and to use this model as an in vitro diagnostic tool for infertility. Significant progress has been made over the years in generating such models. The first experiments of endometrial modeling involved animal models, which are undoubtedly valuable, but at the same time, their dissimilarities with human tissue represent a significant obstacle to further research. This fact led researchers to develop basic monolayer coculture systems using uterine cells obtained from biopsies and, later on, complex and multilayer coculture models. With successful tissue engineering methods and various cultivation systems, it is possible to form endometrial two-dimensional (2D) models to three-dimensional (3D) organoids and novel assembloids that can recapitulate many aspects of endometrial tissue architecture and cell composition. These organoids have already helped to provide new insight into the embryo-endometrium interplay. The main aim of this paper is a comprehensive review of past and current approaches to endometrial model generation, their feasibility, and potential clinical application for infertility treatment.

Antioxidant properties of carotenoids: QSAR prediction of their redox potentials

There is a great need to predict the antioxidant properties of molecules such as carotenoids. These compounds are of great interest due to their contribution to various important biological and industrial processes, including toxicity and fate. In our study, redox potentials were compiled from several literature sources. Redox potential values ranged from 537.2 mV for zeaxanthin up to 691.5 mV for beta-carotene; they correspond to the formation of cation radicals, using the standard calomel electrode (SCE). The redox potential values were measured using conventional electrochemical techniques, cyclic voltammetry and Osteryoung square-wave voltammetry. A quantitative structure-activity relationship (QSAR) was developed to model and consequently to predict the values of redox potential. The predicted values of redox potential for four external carotenoids, namely beta-carotene, zeaxanthin, cantaxanthin and astaxanthin, are presented and discussed. They indicate the dependence of redox potential on structure, donor and acceptor groups and polarisability.