Effect of the dilution rate on the mode of oscillation in continuous cultures of Saccharomyces cerevisiae.

The growth properties of the asymmetric budding yeast Saccharomyces cerevisiae were analysed during spontaneous oscillations in continuous cultures at varying dilution rates D. The length of the oscillation period changed between 1.4 and 14 h in response to the decrease of dilution rate from 0.15 to 0.05 h-1. The distribution of parent and daughter cells in the population was determined microscopically after staining the bud scars and DNA. Most of the data obtained fits a theoretical population balance model assuming two-classes of subpopulations and integer ratios between the generation times of both classes. Some data has to be described by an extended population model assuming there is one parent and two daughter cell classes. How changes of dilution rate may cause an accidental switch of the mode of oscillation is demonstrated. Glucose consumption and metabolite production were measured off-line by enzymatic methods and gas exchange was monitored on-line. All these data of one period point to internal and external signals responsible for the synchronisation of the cell cycle.

The incidence of altered sensation of the mental nerve after mandibular implant placement.

PURPOSE: This study was designed to determine the incidence of altered sensation in patients undergoing mandibular endosseous implant placement. PATIENTS AND METHODS: Ninety-four consecutive patients who underwent the placement of mandibular implants constituted the study group. The only patients that were excluded from this study were those who had preexisting injury to the trigeminal nerve. Patients were followed using standard neurologic testing during the period immediately following implant placement through 6 months. Four hundred five implants were placed in 43 female and 51 male patients. Implant length selection was based on panoramic radiographs using known markers to correct for distortion. In 13 of the patients, the mandibular canal was not adequately visualized, and a computed tomography (CT) scan was used to plan the implant locations. Implants were selected to be located 2 mm above the inferior alveolar canal based on the panoramic images and 1 mm above the canal based on CT images. RESULTS: Eight patients reported altered nerve sensation at their first postimplant visit (8.5%). None of the patients experienced hyperesthesia or dysesthesia. Four of the eight patients with altered sensation had no objective findings or decreased nerve function. One of the patients remained totally anesthetic for 2 months, but reported return to normal function at 4 months. CONCLUSIONS: These findings indicate that a small percentage of patients experience altered sensation after the placement of mandibular endosseous implants. Unlike previous studies, no permanent altered sensation was found. By using proper treatment planning, one can offer endosseous implants with minimal risk of injury to the trigeminal nerve.