Effect of VULM 1457, an ACAT inhibitor, on serum lipid levels and on real time red blood cell flow in diabetic and non-diabetic hamsters fed high cholesterol-lipid diet.

Acyl-coenzyme A: cholesterol O-acyltransferase (ACAT) catalyzes the formation of cholesterol/fatty acyl-coenzyme A esters. Accumulation of cholesterol esters leads to pathological changes connected with atherosclerosis. We have evaluated effects of a newly synthesized ACAT inhibitor, 1-(2,6-diisopropyl-phenyl)-3-[4-(4'-nitrophenylthio)phenyl] urea (VULM 1457), on serum lipid (cholesterol and triglycerides) levels and velocity of red blood cells (RBC) in non-diabetic and diabetic hamsters fed on high cholesterol-lipid (HCHL) diet during 3 months. The VULM 1457 effects on the paw microcirculation were assessed using capillary microscopy by measuring (RBC) velocity in vivo. Hamsters fed on HCHL diet became hypercholesterolemic with a dramatic increase in serum lipids accompanied with significantly decreased RBC velocity. Diabetic hamsters fed on HCHL diet had further increased serum lipids with reduction of RBC velocity. The VULM 1457 inhibitor lowered cholesterol levels in both non-diabetic and diabetic hamsters fed on HCHL diet. The greater VULM 1457 effect was shown in diabetic hamsters fed on HCHL diet where VULM 1457 expressed hypotriglycerides effects, too. An improved RBC velocity-pronounced effect was observed in diabetic hamsters fed on HCHL diet treated with VULM 1457. These results suggest that the ACAT inhibitor, VULM 1457, is a prospective hypolipidemic and anti-atherogenic drug which treats diabetes.

Toxicological evaluation of the new calcium antagonist VULM 993.

The tolerance of the new calcium antagonist VULM 993 was investigated in a series of toxicological studies. The following results were obtained: the maximum tolerated oral dose in acute toxicity was 10,000 mg/kg for mice and 6600 mg/kg for rats, for venous administration it was 26.1 mg/kg in mice and 32.2 mg/kg in rats. In subacute oral toxicity test in rats, VULM 993 showed no toxic effect up to 300 mg/kg/d. The drug was not teratogenic in rats (5, 50 or 250 mg/kg/d, p.o.). VULM 993 did not show any positive response in tests for genotoxicity in vitro. Transplacental study of VULM 993 in rabbits indicated active placental barrier function in the late stage of pregnancy. The toxicological profile of VULM 993 is characterised by a high tolerance in all relevant species of experimental animals, and no biologically significant mutagenic potential was recorded.

Biocompatibility Studies of a New Biosynthetic Dermal Substitute Based on Collagen/Hyaluronan Conjugate.

The use of glycosaminoglycans (GAGs) as the second macromolecular component with collagen for the membrane preparation is based on the idea to create a biodegradable scaffold for new tissue. A hybrid collagen/hyaluronan membrane with specific bubble macrostructure was designed to serve as a synthetic dermal substitute. The objectives were to explain the two questions: what is the local biological response to the implanted membrane, and what is its reconstruction rate in tissue. The histological study proved low irritability, good compatibility, ingrowth of autologous tissue starting on day 7 post implantation, and resorption within four weeks. The major part of the implant was replaced by autologous tissue at the end of three weeks post implantation. The overall local biological response to implant was very good.

Biocompatibility studies of modified collagen/Hyaluronan membranes after implantation.

Two varieties of collagen/sodium hyaluronan membranes were used as dermal substitutes in a biocompatibility implantation study on rats. In order to improve especially the physical and mechanical properties of the material, the membranes were chemically modified using a combination of hexamethylenediisocyanate (HMDC) as a crosslinker and polyoxy-ethylene (POE) as a spacer. According to both macroscopic and microscopic histological observations, the membranes were well accepted by the surrounding host tissue in all the animals. No major differences in relation to the outgrowth of the material by host tissue have been observed between the implant varieties A and B. The most important finding was that no pathological changes or important alterations of the host tissues were detected.

[Detection of calcium in tissues using alizarin red S and optical properties of the reaction product]. / Dôkaz kalcia v tkanivách alizarínovou cervenou S a niektoré optické vlastnosti reakcného produktu.

A histological method of staining calcium deposits in organs and tissues is presented. Staining at different pH provides a certain differentiation of the characteristics of calcium deposits. Further findings concern optical properties of the reaction product of staining observed at examination in polarized light, differential interference contrast (OPTON), and by fluorescence microscopy. The chemical nature of the Alizarin red S reaction product in sites of calcium deposits is discussed.

[Lectin histochemical analysis of the epithelial lining of the appendix in rabbits]. / Lektínová histochemická analýza epitelovej výstelky králicieho apendixu.

The binding of PSA, PNA, HPA, WGA, Con A, LCL, RCA, SBA, and PHA lectins to epithelial structures of the normal rabbit appendix was studied. Differences were observed in the affinity of some lectins to the epithelium of the intercryptal lining of the rabbit appendix, to the epithelium hemming the glandules and crypts of the domes of Peyer's patches. The obtained results document the difference in the affinity of individual batches of anti-WGA antibodies to this lectin after its binding to the epithelial structures studied. This implies the possibility that differently reacting antibodies may develop to different commercially available batches of WGA. Precipitation of WGA at sites of alkaline phosphatase occurrence demonstrates the relationship of this enzyme to WGA binding sites in tissues.

[Structural basis of appendiceal function in rabbits]. / Struktúrne základy funkcie králicieho apendixu.

Enzymo-, immuno- and lactin-histochemical methods were used to study the structure of the rabbit appendix wall. The value of some structural components in the function of this part of the intestine is discussed. Some findings were documented electronmicroscopically. In addition to its resorptive function, the rabbit appendix is equipped with a potent defense mechanism against adverse environmental effects of the appendix content. Individual structures of this defensive barrier are closely characterized with regard to cellular equipment and possibilities of its morphological identification.

[Structural basis of the spleen in rats]. / Struktúrne základy funkcie sleziny potkana.

The basic function of the spleen in the rat, similarly as in man, is to cleanse the blood of damaged old particles of the body itself, but also of foreign particles. To fulfill this function, the spleen is equipped with the white and red pulp with a specific structure of blood circulation. In an open system of circulation, blood from the arterial terminals opens into the cords of the red pulp, where it is adequately processed. From the cords the blood gets through the walls of sinuses, acting as the last filtration barrier, into the lumen of sinuses and then into the venous circulation. Unlike the human spleen, this organ in the rat has a marked marginal sinus and channel systems bridging the marginal zone. The channels mediate the circulation of lymphocytes between the red white pulp.

Teratological study of the herbicide 4-chloro-2-methylphenoxyacetic acid in rabbits.

4-Chloro-2-methylphenoxyacetic acid (MCPA) is an aryloxyacetic acid derivative categorised as a plant hormone herbicide. The aim of the study was to evaluate the effect of MCPA on pregnant females and the prenatal development of rabbits. The substance tested was administered orally to pregnant New Zealand White rabbits from day 6 to day 27 of gestation at doses of 5, 10 and 25 mg kg(-1) day(-1). The animals were killed on day 28 of gestation and live fetuses were examined for gross, skeletal and visceral anomalies. Administration of MPCA did not induce any signs of maternal toxicity. There was a significant decrease of fetal and placental weight compared with controls at the highest dose of MPCA. No adverse effect of the substance tested was seen on uterine content variables, e.g. corpora lutea, pre-implantation and post-implantation loss, early, late resorptions, live and dead fetuses and sex ratio. Rabbit fetuses treated with the middle and highest doses of MPCA had a significantly elevated incidence of skull and pelvic bone delays. In conclusion, prenatal administration of MCPA did not exhibit a teratogenic effect on rabbit fetus development.

[Xanthoid corpuscles in the cytoplasm of rat kidney tubule epithelium]. / Xanthoide Körperchen im Zytoplasma von Tubulus-epithelien der Rattenniere.

In older male rats we found fuchsinophilic granula which appeared both singly and in bale-shaped arrangements in the cytoplasm of the epithelias of proximal, subcapsularly located renal tubuli. In its further development it became apparent that they formed small round-shaped clusters which stained with buffered thionine. These clusters finally united to larger ovoid or cone-shaped homogen formations which detached from cytoplasm and appeared unobstructedly in the lumen of canaliculi and in deeper nephron sections, too. The reason why the authors named these formations "xanthoid" is attributable to their yellowish color. They consist of proteoglycans, are PAS-negative, and resistant to oxidation and lipoid solvents. They appeared both in male rats investigated in a series of toxological tests and in control animals. Female animals were not investigated. In test series carried out later, they could not be found for which reason further investigations were not possible.