[Clinical pharmacokinetics of lidocaine after intraoral nerve block]

Aim of this study was to show the time course of plasma concentrations of 2% lignocaine with adrenalin at a concentration of 1:100,000. Four retinated third molars were removed in one session in 23 patients. For local anaesthesia in each patient we used 10 ml of Xylocaine 2% (Astra), which is commonly used in dentistry. The plasma-concentration was measured for the first 30 minutes after injection of the local anaesthetic using high pressure liquid chromatography (HPLC). Our results suggest that partially intravascular injection could not be avoided although careful aspiration was carried out before injecting. Neither subjective nor objective adverse central nervous effects were seen in our patients. Nevertheless we consider a peripheral intravenous cannula and ECG-monitoring strongly recommended in all major operations under local anaesthesia.

[Resistance of isolated cells from squamous cell carcinomas of the oral cavity to cytotoxic drugs]

Human tumor cells from 22 patients with squamous cell carcinomas of the oral cavity were cultivated in vitro and then subjected to sensitivity tests to cytotoxic drugs such as methotrexate, 5-fluorouracil, cisplatin and bleomycin. Tumor cell proliferation showed drug-specific reaction patterns and time-dose-dependent variations. While the effect of methotrexate on cell proliferation was insignificant, 5-fluorouracil caused a growth suppression of 50%. Cisplatin and bleomycin suppressed cell growth by more than 90%.

Lactate dehydrogenase isoenzymes in squamous cell carcinomas of the oral cavity

Lactate dehydrogenase (LDH; EC 1.1.1.27) isoenzymes in human epithelial cells from squamous cell carcinomas and healthy tissues of the oral cavity of five patients were analyzed using isoelectric focussing. A new basic isoenzyme and high LDH-7 and LDH-9 activity were found in tumor cells in contrast to epithelial cells of adjoining nontumor tissue. These findings indicate that gradual changes in the percentage distribution of LDH isoenzymes may represent a useful parameter of disease activity in patients with squamous cell carcinomas.

Rehydration of lyophilised cartilage grafts sterilized by different methods

In in vitro experiments weight increase and rehydration speed of lyophilised cartilage grafts sterilized by different methods were determined. For periods of up to 72 h the increase in weight during rehydration was measured. The methods of sterilization used is only of little significance for such weight increase. Differences in rehydration speed clearly correlate with the initial weight of the lyophilised cartilage grafts. Smaller grafts are completely rehydrated after 5 to 6 h. This may explain the discrepancies in rehydration speed reported in the literature.

[Effects of different sterilizing techniques on osseous regeneration of grafted lyophilized cartilage]

The suitability of variably sterilized lyocartilage grafts as potential bone substitutes was investigated in animal experiments with special attention to configurational stability. In 3 Beagles corticocancellous implant beds were prepared by box-type ostectomies and lyophilized costal cartilage blocks sterilized with X-rays,ethylene oxide gas and beta-propriolactone solution were placed into them. Implants sterilized with X-rays and beta-propriolactone appeared to be unsuited for recontouring facial bone defects, since they showed complete loss of configuration after a follow-up time of 125 and 230 days, respectively. By contrast, cartilage implants sterilized with ethylene oxide gas retained their configuration after no less than 328 days. In light of these results, methods for sterilizing other biomaterials should be re-considered.

Inhibited methionine incorporation in human squamous carcinomas of the oral cavity as a measure for response to 5-fluorouracil

Human epithelial cells and fibroblasts from malignant tumors and healthy tissues of the oral cavity were exposed in vitro to increasing concentrations of 5-fluorouracil. In order to determine whether the two cell types showed a difference in uptake, accumulation was measured over time using tritiated fluorouracil. Maximal drug uptake occurred in highly proliferative epithelial cells from cancerous tissue at 3 h, whereas fibroblasts from the same tissue and other cell types from healthy tissue exhibited a steadily increasing uptake over a long period of time. By use of [3H]methionine, a direct correlation could be demonstrated between the amount of incorporated drug and the fall in the rate of de novo protein synthesis. Furthermore, suppression of protein synthesis was closely related to the inhibition of cell division. These results indicate that the level of de novo protein synthesis can be a direct measure of the anticancer effect of fluorouracil.