Tooth development disorders in infants of rat dams exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin and protective role of tocopherol and acetylsalicylic acid.

Aryl hybrocardon receptor (AhR) activation plays a key role in the pathomechanism of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced defective spatial structure of teeth caused by disordered collagen synthesis. The aim of this study was to identify the influence of dioxins present in female Buffalo rats on the dental structure of their offspring's in the neonatal period and the potential of α-tocopherol and acetylsalicylic acid in curbing post-dioxin hard tissue defects. Research material consisted of molar teeth (n=40) of rat pups which had been given a single dose of TCDD and were then treated with tocopherol or acetylsalicylic acid for 3 weeks. In the offspring of rat dams exposed to TCDD, ameloblasts and odontoblasts were less developed in comparison with the control group and less dynamic angiogenesis in the area of dental papilla was observed. In the pups of TCDD-exposed mothers, a smaller number of AhR was found in amelogenic and odontoblastic cells, whereas in the pups of mothers exposed to TCDD followed by tocopherol and acetylsalicylic acid treatment, the expression of AhR in ameloblasts and odontoblasts increased. We conclude that tocopherol and acetylsalicylic acid treatment exerts a protective effect on the TCDD-induced structural defects of tooth tissue.

Experimental osteoporosis in sheep--mechanical and histological approach.

The implementation of new methods of osteoporotic therapy requires tests on animal model. The use of sheep as model has numerous advantages over other animals. The aim of this study was to describe the change in parameters in sheep with osteoporosis induced using steroids and ovariorectomy methods as opposed to the parameters in healthy sheep. The study was performed on female "merinos" breed sheep divided into the three groups: negative control (NC)--healthy animals, positive control (PC)--ovariorectomized animals and steroid control group (SC)--in which methylprednisolone was administered. This paper presents histological and ultrastructural examination with mechanical comparative tests for force/strength values as well as indentation tests of joint cartilage. The obtained results confirm the loss of bone mass associated with mineral composition content in bones, which has an influence on bone strength.

The experimental osteoporosis in sheep--clinical approach.

The implementation of new methods of oseoporotic therapy requires tests on an animal model. One of the best is the sheep, whose numerous advantages over other models are described in the literature. The aim of this study was induction of osteoporosis using steroids and ovariorectomy methods in sheep and description of the change in parameters with regard to healthy sheep. The study was performed on female "merino" breed sheep divided into three groups: Negative control (NC) healthy animals, positive control (PC) ovariorectomised animals and steroid group (SC) where methylprednisolone was implemented. Blood tests, diagnostic arthroscopy, quantitative computed tomography and X-Ray micro-tomography of bone were carried out. Blood tests revealed a decreased level of estrogens, progesterone and increased parathormone and cortisol levels in the SC group. A decrease in bone turnover markers and an increase in bone resorption markers in all groups were also noted. Diagnostic arthroscopy revealed osteoarthrosis in PC and SC groups. Radiological density tests showed a slight decrease in PC and NC groups whereas there was more than a triple decrease in SC. Results obtained from microCT showed quickly developing osteoporosis in the SC group, which is reflected in numerous parameters analysed in this study. The best effects for osteoporosis induction were obtained using ovariorectomised sheep with methylprednisolone injections.

Insight into behavior of epithelial cells of the feline conjunctiva in chronic conjunctivitis as a possible limitation in detection of Chlamydophila spp.

The aims of this work was documentation of the reactivity of feline conjunctival epithelial cells in chronic conjunctivitis and the investigation of a possible correlation of histological findings in conjunctiva with a limitation in detection of the pathogen. In this observational study, conjunctival swab samples collected from six cats suffering from chronic conjunctivitis were monitored for Chlamydophila spp. infection for one month, every ten days. Chlamydophilosis was diagnosed by conventional PCR, and confirmed by sequencing analysis. A lack of coherence with results in subsequent studies using PCR did not allow an accurate diagnosis. Additional bioptat samples of conjunctiva were collected for diagnostic purposes and stained in haematoxylin and eosin following the Giemsa method for light microscopic analysis. Additionally the samples were incubated for 15 min with IMAGEN Chlamydia conjugate (IMAGEN Chlamydia reagent kit, Dako, UK), allowing immunofluorescence detection of Chlamydophila spp. Within the epithelium an increased number of goblet cells, as well as general enlargement of the epithelium and a reduced number of normal epithelial cells, was observed. Only in areas of low epithelium could structures similar to the elementary bodies of Chlamydophila spp. be distinguished. The presented data document a possible limitation in molecular evidence for chlamydophila infection in some naturally infected cats, taking into account histological conditions in conjunctiva at the same time.

Influence of antlerogenic stem cells on the healing of lesions in the corneal epithelium and corneal stroma in rabbits.

The aim of the study was to compare the effects of corneal healing in case of application of stem cells in various forms, in relation to the antibiotic-assisted procedures. Rabbits were divided into 4 groups in the first stage of the experiment. Group 0 (negative control group) was not subjected to any actions, which would cause damage to the cornea. The remaining three groups had their cornea damaged. Group 1 (positive control group) - no drugs were administered during the experiment. Rabbits in group 2 were administered with ointment containing stem cells to the lesion, while group 3 - with ofloxacinum. The stem cells were administered during the first five days, twice a day, onto the corneal surface. The further course of the experiment consisted of observing the rate of healing of the injured cornea and assessment of its transparency, size of lesion, hyperaemia, eyelid spasm and outflow from the conjunctival sac after 5, 10 and 20 days.In the second stage the animals were euthanised after clinical examination on the twentieth day of the experiment, in order to analyse the corneal reparative processes on the same day. The studies revealed that the application of antlerogenic stem cells had a positive effect on the healing process of corneal defects. The application thereof not only shortened the healing time, but also weakened or arrested the development of side effects. The results have demonstrated that the epithelial proliferation in each group was different. The longest was maintained in the group with stem cells, the shortest - in the group with chemotherapeutics. The use of antlerogenic stem cells had a positive effect on the healing process of corneal lesions. The use of stem cells helped to maintain high transparency of the cornea.

A model of gallbladder motility.

Impaired gallbladder motility leads to some clinical manifestations associated with its muscle contraction and/or the rate of filling with bile. To gain a better understanding of the possible reasons for different filling/emptying patterns we developed a mathematical model of the gallbladder that takes into account the kinetics of its filling and emptying and changes in the concentration of the accumulated bile. The model is based on four parameters responsible for the maximum speed of bile evacuation (Mg), pulsation of contractions (ω), the kinetic filling rate (kg) and the maximum bile mass accumulated in the gallbladder (mtotal). The model results were fitted to different clinical results describing gallbladder motility depending on the meal composition, patient's age and health condition (obesity and gallstones). Compatibility of the model results with the experimental data allows us to draw physiological conclusions. We found that different gallbladder emptying patterns may result from differences in the amplitude of contraction of gallbladder muscles (e.g. for various meal composition), differences in the rate of bile inflow (e.g. for obese patients during filling), and differences in gallbladder muscle pulsations (e.g. for lean patients during early gallbladder emptying). The model of gallbladder motility can facilitate identification of causes of disorders, help to explore complicated physiological pathways, and can be applied in etiology analysis or studies of observable clinical indicators.

Expression of advanced glycation end-products and NFκB in chick embryos exposed to dioxins and treated with acetylsalicylic acid and α-tocopherol.

Dioxins have adverse and multifaceted effect on body functions. They are known to be carcinogens, immunotoxins, and teratogenic agents. In vivo, transformation of dioxins occurs after their interaction with the aryl hydrocarbon receptor (AhR) and leads to formation of proinflammatory and toxic metabolites. The aim of this study was to verify whether α-tocopherol (vitamin E) and acetylsalicylic acid (ASA), could reduce the damage caused by the action of dioxins. Fertile chicken eggs were injected with a solution of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), followed by the injection of α-tocopherol or acetylsalicylic acid. Organs such as heart and liver were dissected from the chick embryos at d 13 and 19 of development and subjected to immunohistochemical analysis of presence of advanced glycation end products (AGEs) and nuclear factor kappa B (NFκB) in tissues. The AGEs were used as the marker for exposure to dioxins, since it is well established that their level increases in dioxin-damaged tissues. Formation of AGEs was evaluated in embryos exposed to dioxin and treated with vitamin E and/or ASA (against dioxin-exposed, untreated controls). We have found that TCDD causes developmental disorders and increases the level of AGEs in chick embryo tissues. The use of such pharmacological agents as vitamin E, ASA, and combination of ASA and vitamin E, inhibited formation of the AGEs in 13-day-old embryos and reduced the AGEs level in embryos after 19 d of the development.

Increased gene expression of catecholamine-synthesizing enzymes in adrenal glands contributes to high circulating catecholamines in pigs with tachycardia-induced cardiomyopathy.

High levels of circulating catecholamines have been established as fundamental pathophysiological elements of heart failure (HF). However, it is unclear whether the increased gene expression of catecholamine-synthesis enzymes in the adrenal glands contributes to these hormone abnormalities in large animal HF models. We analyzed the mRNA levels of catecholamine-synthesizing enzymes: tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AAAD), dopamine-ß-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) in adrenal glands of 18 pigs with chronic systolic non-ischaemic HF (tachycardia-induced cardiomyopathy due to right ventricle pacing) and 6 sham-operated controls. Pigs with severe HF demonstrated an increased expression of TH and DBH (but neither AAAD nor PNMT) as compared to animals with milder HF and controls (P<0.05 in all cases). The increased adrenal mRNA expression of TH and DBH was accompanied by a reduced left ventricle ejection fraction (LVEF) (P<0.001) and an elevated plasma B-type natriuretic peptide (BNP) (P<0.01), the other indices reflecting HF severity. There was a positive relationship between the increased adrenal mRNA expression of TH and DBH, and the high levels of circulating adrenaline and noradrenaline (all P<0.05). The association with noradrenaline remained significant also when adjusted for LVEF and plasma BNP, suggesting a significant contribution of adrenals to the circulating pool of catecholamines in subjects with systolic HF.

Natural history of experimental intestinal atresia: morphologic and ultrastructural study.

PURPOSE: The aim of this study was to evaluate a natural history of congenital intestinal atresia (IA) in the chick embryo and to assess the type and nature of changes in the intestine at various developmental stages. METHODS: Chick embryos underwent operative induction of IA on the 12th day of incubation. The procedure consisted of electrocoagulation of the mesenteric vessels supplying a 7- to 8-mm intestinal segment. The embryos were subjected to macroscopic examination, histologic and ultrastructural studies of the preatretic and postatretic bowel using the light microscope, scanning, and transmission electron microscopes. All investigations were performed in an experimental group (operated embryos), in a control group, and in a sham-operated group on the 15th, 17th, 19th, and 21st day of incubation. RESULTS: The original technique of an iatrogenic "vascular event" proved to be effective because IA developed in 96% of embryos surviving the procedure. The affected portion of the bowel underwent progressive necrosis, and signs of bowel obstruction could be observed 48 hours after operation. Cord atresia (type II) developed in 81% of embryos. Histologic investigations showed progressive thinning of mucosa, flattening of mucosal folds, and epithelial detachment within the intestine proximal to atresia. There was only mild hypertrophy of the muscular layers. All these pathomorphologic changes were of rapidly progressive nature until the 17th day of incubation. Later, the rate of distension of preatretic bowel and histologic changes were less. Ultrastructural investigation of the proximal bowel showed progressive flattening of the enterocytes associated with their apical bulging, widening of the intercellular spaces, and microvilli atrophy. Surprisingly, at days 19 and 21 of incubation, signs of induction of adaptive mechanisms with partial restoration of near-normal microvilli pattern were observed. CONCLUSIONS: Study of natural history of experimental IA indicates that histologic and ultrastructural lesions of the bowel are of dynamic nature and are not only the effect of pathologic intraluminal pressure.

FT-Raman spectroscopic study of human skin subjected to uniaxial stress.

Fourier Transform Raman Spectroscopy was used to investigate the molecular changes of structural proteins in human skin subjected to strain. In the Raman spectrum of unstrained skin, bands assigned mainly to collagen and elastin were observed at 1658 cm(-1) (amide I), 1271 and 1255 cm(-1) (amide III), and 935 and 817 cm(-1) (C-C stretching modes of the protein backbone). Moreover, bands characteristic for amino acids were observed at 1336 cm(-1) (desmosine), 1004 cm(-1) (phenylalanine), 919 and 856 cm(-1) (proline), and 877 cm(-1) (hydroxyproline). Positions and intensities of the listed Raman bands were analysed as a function of applied strain. A clear correlation between Raman wavenumbers and the level of mechanical stress was established. Wavenumbers of the analysed bands changed gradually with increasing strain. Distinct responses, depending on the sample cutting direction, i.e. longitudinal or perpendicular to the Langer's lines, were noticed. It was concluded that elastin and non-helical domains of collagen are initially involved in the load transfer and triple helices of collagen are gradually joining this process. It was proved that Raman spectroscopy give insight into skin deformation micromechanics.

Gastrointestinal development of dairy calves fed low- or high-starch concentrate at two milk allowances.

The objective was to study the effect of type of concentrate with varying starch and fibre content on growth and gastrointestinal development in preweaned dairy calves. Thirty-two newborn Danish Holstein male calves were allocated to four treatment groups in eight blocks of four calves. An experimental low-starch, high-molasses, high-fibre (EXP) concentrate or a traditional high-starch (TRA) concentrate were fed either at a high (HIGH; 2 × 3.2 kg/day) or a low (LOW; 2 × 1.6 kg/day) whole milk allowance in a 2 × 2 factorial design. TRA contained 350 and EXP 107 g starch/kg dry matter (DM), whereas the NDF content was 136 and 296 g/kg DM, respectively. Metabolizable energy (ME) was 11.2 and 12.2 MJ ME/kg DM in EXP and TRA, respectively. All calves had free access to artificially dried grass hay (9.8 MJ ME/kg DM). Four calves were culled during the experiment. The calves were euthanized either at 38 (12 calves) or 56 days (16 calves) of age. Evaluated across both slaughter ages, there was no difference between TRA and EXP in concentrate and hay intake, rumen weight and papillation. EXP resulted in increased villi number in duodenum and jejunum compared with TRA. Concentrate intake and reticulo-rumen weight was higher for LOW compared with HIGH milk allowance, whereas live weight gain was 20% lower. The results show that a low-starch, high-molasses, high-fibre concentrate with 8% lower ME content tended to reduce daily gain compared with a traditional calf starter concentrate, but resulted in similar ruminal development in preweaned calves both on a high and a low milk allowance fed along with grass hay. Furthermore, the results suggest that the experimental concentrate stimulated intestinal villi growth over that of the traditional concentrate.

[Biological experimental models in orthopedics]. / Biologiczne modele doswiadczalne stosowane w ortopedii.

Experimental research in orthopedics is conducted on different experimental models. Animal models have to be characterized by high similarity and consistence of the animal bone tissue with human metabolism and must undergo similar biomechanical changes. This paper presents the advantages and disadvantages of the most commonly used animal models, with particular attention given to sheep.