Time- and concentration-dependent cytotoxicity of antibiotics used in endodontic therapy

OBJECTIVE: New drugs have to be assessed in endodontic therapy due to the presence of microorganisms resistant to therapeutic procedures. Thus, this study evaluated the time- and concentration-dependent cytotoxicity of different antibiotics used in endodontic therapy. MATERIAL AND METHODS: Human gingival fibroblasts were treated and divided into the following experimental groups: Group I - control; Group II - ciprofoxacin hydrochloride; Group III - clyndamicin hydrochloride; and Group IV - metronidazole. Each drug was used at concentrations of 5, 50, 150, and 300 mg/L for 24, 48, 72, and 96 h. Cytotoxicity was evaluated by the MTT assay [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and spectrophotometric reading of ELISA plates. The results were analyzed by BioEstat 4.0 software using Kruskal-Wallis and Dunn's tests at a signifcance level of 5 percent. Cell viability was assessed for the different concentrations and times. RESULTS: All drugs presented dose-dependent cytotoxicity. Concentrations of 5 and 50 mgjL produced viable fibroblasts at all experimental times in all groups. CONCLUSIONS: Cell viability at 24 h was greater than in the other experimental times. Comparison between the same concentrations of antibiotics at different times showed that metronidazole presented the highest cell viability at 72 and 96 h compared to the other antibiotics, whereas clyndamicin hydrochloride showed higher cell viability at 72 h than ciprofoxacin hydrochloride.

Differential role of MAP kinase isoforms in malachite green transformed Syrian hamster embryo fibroblasts in culture.

Malachite green (MG) induces DNA damage and malignant transformation of Syrian hamster embryo (SHE) cells in primary culture. In the present study, we have studied the role of all the three isoforms of mitogen activated protein (MAP) kinases i.e. ERK (extracellular regulated kinase), JNK (JUN- N- terminal kinase) and p38 kinase during transformation of SHE cells by MG. The results showed that transformed cells were associated with a decreased expression of phosphoactive ERK and JNK and increased expression of p38 kinase as evident from the Western blot, immunofluorescence and flow cytometry studies. Also, a persistent nuclear localization of p38 kinase was observed in the transformed cells. The present study indicated that p38 kinase was present at higher levels and seemed to be associated with transformation, which suggested that inhibitors of p38 kinase could serve in general as potential agents for selective cancer therapy.

Ultrastructural changes in cauda epididymidal epithelial cell types of Azadirachta indica leaf treated rats.

To assess if cauda epididymis is a target for the effect of A. indica leaves, Wistar strain male albino rats were administered (po) A. indica leaves (100 mg/rat/day for 24 days). Transmission electron microscopic analysis revealed that in the cauda epididymal epithelium the nuclei of principal cells were enlarged and the number of coated micropinocytotic vesicles of the apical cytoplasm decreased. Microvilli were missing and mitochondrial cristae and Golgi complex were highly disrupted. The cytoplasm was abounding with lysosomal bodies. The clear cells increased in perimeter and their nuclei increased in size and contained lesser chromatin. The nuclear membrane bulged out. The cytoplasm was vacuolized. Further, there was decrease in size of the lipid droplets, mitochondria, Golgi complex, endoplasmic reticulum and there was accumulation of lysosomal bodies. The changes in the principal and clear cells appear to be due to the effect of the hypoandrogen status caused by treatment with A. indica leaves and a direct action on the epididymal epithelium.

First ovarian maturity and recovery response in common carp, Cyprinus carpio after exposure to carbofuran.

The present study embodies the observations on duration (45, 75 and 105 days) dependent effects of toxicologically low concentration (16 ppm) of a carbamate pesticide, carbofuran, on first ovarian maturity with correlative recovery response by withdrawal of treatment for 30 days in virgin yearlings of common carp, Cyprinus carpio var. Communis. In control fish histological organization of ovary and changes in gonado-somatic index (GSI) revealed the initiation of oocyte differentiation and development at the commencement of experiment in December-January and peak of maturation with fully grown yolky oocytes was attained by the time of termination of experiment in the end of March. In carbofuran exposed groups ovaries exhibited retardation of development and growth evident by significantly decreased GSI and predominace of immature oocytes passing through nuclear-cytoplasmic degeneration of variable magnitude. Severity of degenerative changes was more pronounced with prolonged duration. In recovery group ovaries had experienced regeneration as clued by the presence of oocytes of differential stages including vitellogenic and fully grown oocytes. In liver histopathological changes coupled with significant decrease in hepato-somatic index (HSI) attributed hepatic inactivation in all exposure groups whereas in recovery group an increase in HSI value with marked sign of hepatic reactivation was evidenced. No significant change in values of condition (CF) and somatic condition (SCF) factors substantiated the over all normal health of fish. Lipid and water content of ovary, liver and muscle registered the significant decrease at 105th day of exposure with concomitant augmented value for recovery group. These observations suggest that the commercial formulation of carbofuran, even at this toxicologically low concentration, is equally capable of affecting the first ovarian maturity with associated physiological implications but with reversibility in toxicity by withdrawal of pesticide exposure attributing regeneration in affected organs in due course time.

Toxicological studies of pesticides on cytoplasmic streaming in Nitella.

In the present study, changes in velocity of cytoplasmic streaming in the giant internodal cells of Nitella for varying concentration of the pesticides, 2,4-D, dieldrin, malathion, methyl parathion and endosulfan, were measured. Marked decrease in the velocity of cytoplasmic streaming was found at the concentrations of 0.01, 0.1, 1, 10 and 100mM. Dieldrin was the most toxic to all the pesticides investigated, followed by methyl parathion, endosulfan, malathion and 2,4-D. Threshold values for dieldrin, methylparathion, endosulfan, malathion and 2,4-D as indicated by the onset of decrease in the normal cytoplasmic streaming velocity were less than 6.25 x 10(-6), 2.5 x 10(-5), 5 x 10(-5), 5 x 10(-5) and 1.25 x 10(-5)M respectively. Cessation of streaming was noticed above 1mM in dieldrin and above 10mM when exposed to methylparathion and endosulfan. Cessation of streaming was not seen up to 100mM concentration of 2,4-D and malathion.

Ultrastructural effects of two phthalocyanines in CHO-K1 and HeLa cells after laser irradiation

The effects of Photodynamic Therapy using 2nd generation photosensitizers have been widely investigated aiming clinical application treatment of solid neoplasms. In this work, ultrastructure changes caused by the action of two 2nd generation photosensitizers and laser irradiation on CHO-K1 and HeLa (neoplastic) cells were analyzed by transmission electron microscopy. Aluminum phthalocyanine chloride, aluminum phthalocyanine tetrasulfonate chloride and radiation from a semiconductor laser at a fluency of 0.5 J/cm2 (Power=26 mW; lambda=.670 nm) were used. The results showed induction of apoptosis. Such alterations where observed in HeLa but not in CHO-K1 cells after Aluminum phthalocyanine tetrasulfonate chloride (AlPcS4, photodynamic treatment. The Aluminum phthalocyanine chloride (AlPc) photodynamic treatment induced necrosis on the neoplastic cell line, and cytoplasm and nuclear alterations on the normal cell line.

Comparative responses to salinity in wheat genotypes differing in salt tolerance 2-cell permeability, osmotic potential and cytoplasmic viscosity

Caryopses of two Triticum estivum genotypes, differing in salt tolerance [Sakha 8, tolerant, Giza 162, sensitive], were hydroponically grown under natural environmental conditions [in the laboratory] in presence and absence of different concentrations of NaCl added to the growth medium. NaCl stress increased nonelectrolyte permeability of leaf sheath subepidermal cells in Giza 162 [sensitive], whereas no such effect of salt was found in Sakha 8 [tolerant]. Psi s of leaf sheath subepidermal cells of both cultivars was decreased with rising NaCl concentration in the external solution. At 100 mM NaCl, the decrease in psi s in Giza 162 was greater than that found in Sakha 8. Cytoplasmic viscosity of Giza 162 was decreased by NaCl addition to the growth solution, although viscosity was higher in Giza 162 than in Sakha 8 under control condition [O mM NaCl]. Cytoplasmic viscosity in Sakha 8, however, did not change by salt stress. The results confirmed and extended earlier data that cytoplasmic characteristics are different in wheat salt sensitive and tolerant genotypes, they may correlate with salt tolerance

Effect of sodium selenite on the hepatotoxicity induced with carbon tetrachloride

The authors have demonstrated the effect of sodium selenite on the hepatotoxicity due to carbon tetrachloride, by observing the distribution and disaggregation of the pyroninophilic granules in the hepatic cell of the mature male albino mice. Each experimental mouse of the selenite and the selenite plus carbon tetrachloride groups was given a single dose of 4 ug. of sodium selenite per kilogram of body weight and that of the control and the carbon tetrachloride groups was given 0.1 ml. of distilled water alone. Six hours after the first administration of distilled water or sodium selenite, the experimental mice of the carbon tetrachloride and the selenite plus carbon tetrachloride groups were given a single dose of l.0 ml. of carbon tetrachloride per kilogram of body weight and those of the selenite groups were given 0.l ml. of paraffin oil alone. Following the 1ast administration of carbon tetrachloride or paraffin oil, the mice were sacrificed by bleeding (cutting the common carotid artery) at the intervals of 2,3,4,6,8, and 12 hours respectively. Histochemical preparations were stained by the methyl-green and pyronin method and oil red 0 method. The hepatotoxicity due to the administration of carbon tetrachoride was evident in the hepatic cells; the pyroninophilic granlues were partly reduced in volume in the hepatic cells of the centrilobular and the intermediate zones as early as the 3 hour-period, and markedly reduced or disappeared in the centrilobular and some part of the intermediate zones associated with hydropic degeneration as well as in the 6 hour-period. Thereafter marked reduction or dissolution of the pyroninophilic granules was found and extended as the periportal zone at the 12 hour-period. However, the pyroninophilic granules in the hepatic cells of selenite plus carbon tetrachbride group showed no significant changes in the hepatic cells of these zones, compared to the histochemical feature of the granules in the hepatic cells of the control and the selenite groups. Consequently it is suggested that the lipid peroxidative decomposition of the microsomal membranes, which is induced with carbon tetrachloride, would be prevented by a previous administration of sodium selenite.