Comparative effects of local anesthetic preparations on gingival fibroblasts of the rat

Influence of intradiscal medication on nucleus pulposus cells

BACKGROUND CONTEXT

Eugene Carragee was the first to prove that provocative discography may contribute to intervertebral disc degeneration. Disc degeneration can be induced either by mechanical trauma caused by the puncturing needle or as a pharmacological effect of the drugs instilled into the disc.

PURPOSE

The aim of this study was to test the influence of cortisone, lidocaine, and iopamidol on nucleus pulposus cells under an in vitro setting.

STUDY DESIGN

Controlled in vitro study is the design type.

METHODS

The nucleus pulposus was excised from 12 bovine tail intervertebral discs and monolayer cell cultures were generated. The cultures were divided into four sample groups and incubated in either standard cell culture medium (control group) or medium supplemented with the test substances. The dose rate was adapted based on a total dose of 3 mL iopamidol, 1 mL lidocaine, and 10 mg cortisone per nucleus pulposus. Cell count, viability, proliferation, and differentiation features were analyzed. The study was supported by DePuy. No conflicts of interest arise from this support.

RESULTS

After 24 hours, a significant decrease in cell counts was observed in all three test groups. Population doubling time was 16 hours in the control group cultured in standard medium and increased to 21 hours (cortisone), 25 hours (iopamidol), and 38 hours (lidocaine) after incubation in discography medication (p<.001). Cell viability was slightly, but not significantly decreased in all medication groups. Cells incubated in Lidocaine were significantly smaller (p<.01) and showed clearly reduced pseudopodia formation. Incubation in lidocaine and iopamidol also significantly reduced glycosaminoglycan synthesis.

CONCLUSION

Although only a small decrease in cell viability was observed in all three substances tested, cell count and proliferation decreased significantly. Incubation in lidocaine inhibited pseudopodia formation and might therefore interfere with intercellular signalling and cell migration. Glycosaminoglycan synthesis was significantly decreased after contact with lidocaine as well as Iopamidol. These observations suggest that all three medications tested might interfere with biological repair mechanisms of the intervertebral disc and therefore contribute to a further degeneration.

An early and late cytotoxicity evaluation of lidocaine on human oral mucosa fibroblasts

Local anesthetic drugs are extensively used in dentistry. However, the cytotoxic effects of these pharmaceutical compounds remain unclear. In this work, we have evaluated the cell viability and cell function of human oral mucosa fibroblasts exposed to different concentrations of lidocaine for increasing incubation times, using a global screening methods including structural, metabolic and microanalytical analyses. Our results demonstrate that lidocaine is able to alter cell viability and function even at low concentrations and times, although the effect of lidocaine concentration was more important than the incubation time. First, the structural analysis methods revealed that ≥5% concentrations of lidocaine are able to significantly reduce cell viability. Then, the metabolic 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-1) assays suggest that concentrations starting from 1% were able to significantly hinder cell physiology. Finally, electron-probe X-ray microanalysis confirmed the deleterious effects of lidocaine and allowed us to demonstrate that these effects are associated to an apoptosis process of cell death. Therefore, care should be taken when lidocaine is clinically used, and the lowest efficient concentrations should always be used. Furthermore, these results suggest that the comprehensive evaluation method used in this work is accurate and efficient for screening of local anesthetics.

The effect of local hematoma blocks on early fracture healing

To test the effects of lidocaine and bupivacaine on early fracture healing, the tensile strength of five groups of femora from normal rats 14 and 35 days after production of a closed diaphyseal fracture were compared. Data indicate that, in experimental animals injected with local anesthetics at the fracture site, no measurable difference is noted in callus composition, tensile strength, or histological appearance during the early phases of fracture repair prior to callus remodeling.

Prilocaine induces apoptosis in osteoblastic cells

PURPOSE

To determine whether prilocaine, a local anesthetic, induces apoptosis in osteoblastic cells.

METHODS

After reaching subconfluence, human osteoblastic Saos-2 and MG63 cells and mouse osteoblastic MC3T3-E1 cells were exposed for 48 hr to varying concentrations of prilocaine up to 10 mM and the cytotoxicity of the cells was analyzed by phase-contrast microscopy and WST-1 assay. Saos-2 cells treated for 48 hr with 5 mM prilocaine were stained with Hoechst 33342 and nuclear fragmentation was examined under a fluorescence microscope. DNA was extracted from the cells treated with 5 mM prilocaine and DNA ladder formation (a hallmark of apoptosis) was analyzed by agarose gel electrophoresis.

RESULT

Prilocaine induced cell death in Saos-2 cells in a dose- and time-dependent manner up to the concentration of 10 mM. Marked nuclear condensation and fragmentation of chromatin were observed in the prilocaine-treated cells. DNA ladder formation also was induced by prilocaine treatment. Prilocaine-induced DNA ladder formation was dose-dependent with maximal effect at a concentration of 5 mM and was time-dependent from 12 to 48 hr. DNA ladder formation was also induced by prilocaine treatment in human osteoblastic MG63 cells and mouse osteoblastic MC3T3-E1 cells. Cycloheximide prevented prilocaine-induced apoptosis in Saos-2 cells in a dose-dependent fashion up to 20 microM as determined by WST-1 assay and DNA ladder formation in agarose gel electrophoresis.

CONCLUSION

Osteoblastic cells treated with prilocaine exhibit both morphological and biochemical features indicative of apoptosis. The apoptotic mechanisms involve transcriptional regulation of specific proteins or protein synthesis.

The effect of lidocaine on growth of cells of head and neck squamous cell carcinoma

The effect of lidocaine on the growth rate of human squamous cell carcinoma of the head and neck area was investigated in tissue culture. As growth parameters, the mean cell area, the total cell area, the field area and the total number of cells have been measured by digital image analysis. The carcinoma's two cell types--round and spindle--were recorded separately to verify different patterns of alteration. All parameters did not decrease significantly when lidocaine was given as a single dose prior to the culture. A significant decrease (p < 0.05) at day 6, 9 and 12 in culture was found when lidocaine (7 micrograms ml-1) was added to the culture medium.

Trends in dental fluorosis and dental caries prevalences in Newburgh and Kingston, NY

A study was undertaken in New York State to determine the changes in dental fluorosis prevalence from 1955 to 1986 in fluoridated Newburgh and non-fluoridated Kingston children. The frequency and severity of dental fluorosis among 884 7-14-year-old children were measured by two dentists utilizing Dean's Index. Data regarding residential and fluoride history were obtained from the parents of participants. Among the Newburgh residents, the prevalence of dental fluorosis (very mild to moderate) varied from a low of 5 per cent for the 9-10-year-old group to a high of 9.4 per cent for 11-12-year-olds. Except for the 13-14-year-old group, children in non-fluoridated Kingston had the lowest dental fluorosis prevalence rates. A comparison of Dean's Community Fluorosis Indices to the 1955 baseline data obtained from studies conducted after 10 years of fluoridation in Newburgh revealed no changes of consequence among Newburgh residents. However, the changes are apparent for Kingston residents, indicating the availability of fluorides in non-fluoridated areas. The increased risk for dental fluorosis for Kingston residents appears to be from the use of fluoride tablets. An analysis of dental caries data revealed that caries prevalence declined substantially in both fluoridated and non-fluoridated areas.

Regulation of salivary proteins

Previous studies have shown that several factors--such as alloxan-induced diabetes, adrenalectomy, or removal of the thyroid-parathyroid gland complex--can influence the flow rate, protein concentration, and protein composition of rat parotid saliva. The present study was undertaken to explore further the influence of glucocorticoids and thyroxine on rat parotid saliva in hormonally intact animals. As compared with untreated animals, adult male rats treated with 10 micrograms dexamethasone per 100 g body weight for eight days demonstrated a 75% reduction in volume of parotid saliva secreted in response to a uniform stimulus. The protein concentration of the saliva was increased three-fold. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed relative decreases in acidic and basic proline-rich proteins and in a protein identified as Fraction V, while amylase was increased. The electron microscopic appearance of the granules was markedly different from that of the control, in that the granules exhibited an electron-dense periphery and core, with the remainder of the granule having an electronlucent appearance. In contrast, rats treated for eight days with 20 micrograms thyroxine per 100 g body weight exhibited a 50% increase in volume of saliva collected in response to a secretory stimulus. Although the concentration of protein was not different from that of the control, gel electrophoresis showed relative increases in acidic and basic proline-rich proteins and a decrease in Fraction V. Amylase was unchanged. The secretory granules of thyroxine-treated rats were electronlucent and amorphous. The granules appeared to coalesce within the cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Review of systemic fluoride supplementation and consideration of the pharmacist's role

Interprofessional contact and consultation among dentists, physicians, and pharmacists can help to optimize patient care. Because pharmacists are readily accessible to the public, their influence is essential for the appropriate prescribing and continued use of systemic fluoride supplements. Pharmacists should be familiar with various aspects of fluoride therapy, such as mechanisms of caries inhibition, dosages associated with acute and chronic toxicity, and recommended daily dosage levels. The impact of breastfeeding, multiple sources of water intake, and changing age of the patient must be considered in determining proper systemic fluoride dosage. Pharmacists should consult with both physicians and dentists to coordinate water fluoride assay and prescribing responsibilities. They also can help to educate both prescribers and patients. Because of frequent patient contact and access to medication records, pharmacists can encourage and monitor patient compliance. Fluoride prescriptions and results of water fluoride assays should be documented on the patients' computerized or card profiles. In addition, pharmacists can counsel patients about the fluoride ion content of various home-use products and make recommendations to ensure that an optimal level of fluoride ingestion is maintained.