Do effects of propranolol on the skeletal system depend on the estrogen status?

BACKGROUND: Propranolol, a nonselective ß-adrenergic receptor antagonist, was reported to favorably affect the skeletal system in different animal models. The aim of the study was to investigate whether the effects of propranolol on the skeletal system depend on the estrogen status. METHODS: The in vivo experiments were carried out on the following groups of mature female Wistar rats: sham-operated control rats, sham-operated rats receiving propranolol, ovariectomized (OVX) control rats, OVX rats receiving propranolol, OVX rats receiving estradiol, OVX rats receiving estradiol and propranolol. Propranolol hydrochloride (10 mg/kg po) and/or estradiol (0.1 mg/kg po) were administered daily for 4 weeks. Bone mass, mineral and calcium content, macrometric and histomorphometric parameters, and mechanical properties were examined. In vitro, effects of estradiol and propranolol on the formation of mouse osteoclasts and on the mRNA expression of genes related to osteoclastogenesis, bone formation and mineralization, as well as adrenergic and estrogen signalling in mouse osteoblasts were investigated. RESULTS AND CONCLUSION: Propranolol exerted some favorable effects on the rat skeletal system in vivo, independently of the estrogen status. However, in vitro studies indicated a possibility of some antagonistic relations between the estradiol and propranolol effects.

Fluorescence spectroscopy as tool for bone development monitoring in newborn rats.

Autofluorescence of the mandible and femur bones taken from newborn rats (7-, 14- and 28-day old) was studied. Endogenous fluorophores were excited with 231 nm, 291 nm, 340 nm and 360 nm wavelengths. Modifications in content and microenvironment of both noncolagenous and collagenous constituents of bone tissue as well as metabolic coenzymes during the bone formation with age were reflected in fluorescence emission spectra. The increase of emission from peptide bonds and tryptophan residues was noted with rat age while for collagen and metabolic coenzymes at the first 2 weeks only. After maternal administration of indinavir the changes in fluorescence intensity and shifts in position of peak maximum were found. The distinct drop of emission from peptide bonds and tryptophan residues in studied bones was detected. In the case of collagen and metabolic coenzymes the red shift of peak maximum was revealed. Fluorescence spectroscopy could be used to follow bone development in newborn rats and effect of maternal indinavir administration on offspring.

Optical and X-ray fluorescence spectroscopy studies of bone and teeth in newborn rats after maternal treatment with indinavir.

An experiment estimating influence of antiviral drug indinavir treatment during pregnancy on bones and teeth development in newborn rats was performed. Two different fluorescence noninvasive spectroscopy techniques, i.e. laser (407 nm)-induced fluorescence method to characterize the organic fluorescent molecules and X-ray fluorescence analysis to determine mineral components were used to study the surface response of femur, mandible and incisor during their formation in the first month of a rat's life. Differences in autofluorescence depending on the form of the bone were observed on the basis of the emission from enamel in 7-, 14- and 28-day-old newborn rats. The dependence between decrease in intensity of fluorescence and increase in mineralization with age in newborn rats was observed. An enhancement of the autofluorescence and a decrease in the concentration of Ca as a main element, as well as disturbances in the concentration of Zn as trace element were observed for bone as well as teeth in newborns during the first month of their life after maternal administration of indinavir (500 mg kg(-1) p.o.) in comparison with the control group. The results indicate that indinavir causes a delay in development of the skeleton and teeth in newborn rats.

Effect of low-dose tacrolimus coadministered with raloxifene on the skeletal system in male rats.

Tacrolimus is an immunosuppressive drug, used to prevent organ transplant rejection. Immunosuppresants are known to unfavorably affect the osseous system. However, in our previous study on bone histomorphometric parameters we observed that low-dose tacrolimus intensified bone formation. The aim of the present study was to investigate the effects of low-dose tacrolimus on bone mechanical properties and mineralization in male rats. The effects of concurrent administration of tacrolimus and raloxifene were also studied. Raloxifene is a selective estrogen receptor modulator, used in the prevention and treatment of postmenopausal osteoporosis. In male rats raloxifene induces moderate intensification of bone mineralization. The experiments were carried out on mature male Wistar rats. The animals were divided into four groups (n = 7): control rats, rats treated with tacrolimus (0.3 mg/kg po), rats treated with raloxifene hydrochloride (5 mg/kg po) and rats treated with tacrolimus and raloxifene hydrochloride concurrently at abovementioned doses. The drugs were administered daily for 4 weeks. Body mass, bone mass and bone mineral content in the tibia, femur and L-4 vertebra, as well as mechanical properties of the whole femur (extrinsic stiffness, ultimate and breaking load, deformation caused by the applied load) and the femoral neck (load at fracture) were examined. Administration of tacrolimus at a dose of 0.3 mg/kg po for 4 weeks did not affect bone mechanical properties and mineralization. Concurrent administration of tacrolimus and raloxifene resulted in changes similar to those caused by raloxifene alone (statistically significant increases in the bone mass/body mass ratio, bone mineral content/body mass ratio and bone mineral content/bone mass ratio in comparison with the control rats, and no effect on bone mechanical properties). Results of the present study do not support the hypothesis that tacrolimus may be useful as a drug stimulating bone formation in skeletal diseases.

Effects of natural phenolic acids on the skeletal system of ovariectomized rats.

Recent reports indicate the possibility of antiresorptive and/or bone formation increasing activity of natural phenolic acids, commonly present in plants which are normally consumed in the diet. The effects of 4 natural phenolic acids (ferulic, caffeic, P-coumaric or chlorogenic, 10 mg/kg P. O. daily for 4 weeks) on the skeletal system of ovariectomized (estrogen-deficient) rats were investigated. Bone mass, mineral and calcium content, macrometric and histomorphometric parameters, and mechanical properties were examined. Phenolic acids differentially affected the skeletal system of rats with osteoporotic changes induced by the ovariectomy. Caffeic acid decreased bone mass, whereas P-coumaric acid increased the bone mass/body mass ratio and bone mineral mass/body mass ratio in the long bones, in comparison with the ovariectomized control rats. The phenolic acids improved some bone histomorphometric parameters, impaired by estrogen deficiency. However, they did not increase the ratio of bone mineral mass to bone mass, decreased by estrogen deficiency, and did not significantly affect bone mechanical properties. In conclusion, different natural phenolic acids exert differential effects on the skeletal system of ovariectomized rats, both favourable and deleterious.

A comparative study of the effects of genistein, estradiol and raloxifene on the murine skeletal system.

Genistein, a major phytoestrogen of soy, is considered a potential drug for prevention and treatment of postmenopausal osteoporosis. The aim of the present study was to compare the effects of genistein, estradiol and raloxifene on the skeletal system in vivo and in vitro. Genistein (5 mg/kg), estradiol (0.1 mg/kg) or raloxifene hydrochloride (5 mg/kg) were administered daily by a stomach tube to mature ovariectomized Wistar rats for 4 weeks. Bone mass, mineral and calcium content, macrometric parameters and mechanical properties were examined. Also the effects of genistein, estradiol and raloxifene (10(-9)-10(-7) M) on the formation of osteoclasts from neonatal mouse bone marrow cells and the activity of osteoblasts isolated from neonatal mouse calvariae were compared. In vivo, estrogen deficiency resulted in the impairment of bone mineralization and bone mechanical properties. Raloxifene but not estradiol or genistein improved bone mineralization. Estradiol fully normalized the bone mechanical properties, whereas genistein augmented the deleterious effect of estrogen-deficiency on bone strength. In vitro, genistein, estradiol and raloxifene inhibited osteoclast formation from mouse bone marrow cells, decreasing the ratio of RANKL mRNA to osteoprotegerin mRNA expression in osteoblasts. Genistein, but not estradiol or raloxifene, decreased the ratio of alkaline phosphatase mRNA to ectonucleotide pyrophosphatase phosphodiesterase 1 mRNA expression in osteoblasts. This difference may explain the lack of genistein effect on bone mineralization observed in ovariectomized rats in the in vivo study. Concluding, our experiments demonstrated profound differences between the activities of genistein, estradiol and raloxifene towards the osseous tissue in experimental conditions.

Monitoring Legionella species in hospital water systems. Link with disease and evaluation of different detection methods.

The aim of this work was to evaluate three currently available isolation methods for Legionella using water samples and swabs of a single pediatric hospital water system. Additionally, high risk patients were screened for the presence of Legionella pneumophila antigen in urine. Fifteen water samples and 11 swab samples were collected from distal sites at 18 sampling locations. The International Standard Method (PN-ISO11731-2) based on membrane filtration and direct culture of bacteria on selective media were compared with amoebic co-culture. The numbers of legionellae detected exceeded 10(2) cfu/100 ml in 50% of the samples. All the positive samples contained L. pneumophila SGs 2-14. Urine samples were obtained from 57 immunosuppressed children and screened for the presence of L. pneumophila serogroup (SG) 1 antigen by Legionella urinary antigen EIA. Of the 57 urine samples tested for the presence of Legionella pneumophila SG 1 antigen, none were positive. Our results highlight the value of combined membrane filtration and amoebic co-culture methods in detecting viable L. pneumophila strains. Direct plating of 0.2 ml water is a useful screening method for samples containing large bacterial amount.

[The study of adhesion of Candida albicans to the selected acrylic resins]. / Ocena stopnia przyczepnosci candida albicans do wybranych tworzyw a krylowych.

The study has been performed on 3 acrylic resins used to fabricate removable dentures. Aim of the study was to detect possible differences in Candida albicans' adhesion within particular materials. Polished and non-polished samples were made, than these samples were sunk in precipitates containing Candida albicans material. Adhesion of Candida albicans to the surface of the materials occured within a concentration of 10. After 24 hours of incubation differences were found concerning the number of the plate cultures. Most of all plate cultures were observed on Lucitone 199, fewer on Zhermacryl, the poorest one was found on Palaxpress resin. Considerable number of plate cultures occured on non-polished samples relating to polished ones. After 48 hours of incubation further development of Candida albicans took place, with differences concerning various materials.