Biomedical subjects
Publications and source records attributed to K H Ott.
Rapid classification and identification of the mode-of-action of bioactive compounds applied to plants can be achieved by a robust and easy-to-use metabolic-profiling method. This method uses artificial neural network analysis of one-dimensional proton NMR spectra of aqueous plant extracts to rapidly classify changes in the total metabolic profile caused by application of crop protection chemicals.
OBJECTIVES: Carisolv is a viscous substance for the chemo-mechanical removal of caries. The aim of this study was to examine the tissue reactions of pulp and dentin tissue to Carisolv in vivo. METHODS: In 48 caries-free molars (24 Wistar rats, age: 3 months) an occlusal cavity was prepared. The roofs of the pulp chambers were perforated with a sharp probe and Carisolv solution was placed onto the exposed pulp of 24 molars for 1, 10 and 20 min. Twenty-four contralateral molars served as controls and were coated with an inert liquid containing isotonic saline solution, carmellose and erythrosin. RESULTS: After a contact period of 10 and 20 min in the experimental group, pulpal destruction of intercellular substance and cells including odontoblasts was observed up to a depth of 150 microm, in addition to the mechanical damage by perforation (e.g. dentin particles). The pulpal and predentin fibrils as well as the dentin fibrils appeared to be intact and did not differ from the controls. After a contact time of 1 min a weaker damage of pulp cells and odontoblasts, as well as intact fibrils in pulp, predentin and dentin could be observed. CONCLUSIONS: Radicals of Carisolv (OH- and OCI-) cause alkaline hydrolysis of cellular components but do not decompose collagenous tissue components.
Plants with specific resistance to a single class of herbicides have been genetically engineered by introduction of genes encoding rationally designed mutant acetohydroxyacid synthase (AHAS) enzymes. Suitable substitution mutations were identified from a three-dimensional model of an AHAS-inhibitor complex. The structural model was generated based on homology to pyruvate oxidase and an imidazolinone inhibitor was positioned in the proposed binding site using structure-activity data for this class of herbicide. Biochemical analysis of the mutant proteins expressed in Escherichia coli enabled iterative optimization of the mutant genes. Expression of recombinant proteins in tobacco plants conferred resistance in vivo. The novel approach coupling molecular modeling and molecular biology has many advantages over traditional random mutagenesis and selection methods and will be crucial to the future development for environmentally safe and sustainable agricultural systems.
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The discovery of mutations in the gene for Cu/Zn superoxide dismutase (SOD) in some cases of familial amyotrophic lateral sclerosis (FALS) provides a rationale for enzyme replacement therapy. The inability of SOD to cross the blood-brain barrier motivated this study of the safety, tolerability and pharmacokinetics of bovine SOD (bSOD) administered into the CSF of rhesus monkeys and one late-stage, SOD-deficient FALS patient. Kinetic analyses in the patient indicated that intracerebroventricular (i.c.v.) administration, but not lumbar administration, delivered bSOD to the entire CSF pathway. Daily bolus i.c.v. injections (32 mg/day) and continuous i.c.v. infusion (30 mg/day) were well tolerated by the patient. During the period of daily bolus injections, the patient's performance on manual muscle tests was nearly stable, in contrast with the rapid decline before and after that period. These results justify further investigation of bSOD therapy in SOD-deficient FALS patients.
We have investigated the structure of mu-conotoxin GIIIA by 2D-NMR methods. The assignment of 1H NMR spectra and a quantitative analysis of NOE and J-coupling data are presented. These results were used for the calculation of secondary structure elements of mu-conotoxin GIIIA. Distance geometry calculations were carried out to define the global folding of the peptide.
The mercury concentrations in the hair of 53 dentists, 49 dental assistants, 35 dental students and 35 non-exposed persons were analyzed by AAS and compared with a group of 22 factory workers producing chloride gas. The average mercury concentrations in the hair of the dentists was found to be twice as high as the amount measured in the non-exposed population, but only one quarter of that established for the factory workers. The dental assistants had 50% more mercury in their hair than the non-exposed group. The mercury concentrations did not correlate with age, sex, or number of amalgam fillings, but rather with the daily/weekly consumption of fish. The mercury concentrations in the hair of dentists and dental personnel found in this study were low, even when compared with international results; toxicologically their importance is negligible.
The reproducibility of movement recordings obtained with the Condylocomp LR 2 was tested on three different types of articulator (Dentatus, SAM 2, Stuart). Additionally, reproducibility of TMJ movement recordings was tested on 18 subjects. Differences of +/- 2 degrees to the real angles, when working carefully, seem to be precise enough. The Condylocomp LR 2 seems to be a useful means for diagnosing and documenting TMJ movements, because it allows dynamic recordings with high resolution and correction of geometric errors.
Six electrical instruments for locating the apex during endodontic treatment were tested in a laboratory investigation about currency, frequency and scale. Further we looked, whether all instruments show coincidence in the apex point. There are great differences in currency, frequency and scale (apex point). The reproducibility and the precision of an apex locator--at the time--depends an many factors and thus indication seems to be very limited.
In a clinical study on 100 root canals we measured the difference between the length, which can be received by a roentgenogramme, and the length, which can be received by an electrical device. In cases with vital exstirpation in 80% we got a good conincidence, but in cases of pulp gangraena there were great differences. Indication of electrical devices for measuring tooth length only can be seen together with an existing X-ray; it is very important, whether the canal is dry enough for exact measuring.
Carious morbidity, oral hygiene, periodontal health, use of fluoride and therapeutic compliance were investigated in a clinical study of 41 children who had previously required insufflation anaesthesia for dental therapy. All of the children underwent postoperative treatment willingly; anaesthesia was not necessary in any of the cases. Half of the children still had a raised risk of caries; gingivitis was present in all of the children as a result of insufficient oral hygiene. For these reasons, all children that have undergone dental therapy under anaesthesia must subsequently be integrated in a programme of selective intensive prophylaxis.
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Temperature was measured during polymerization of 24 composite materials within 5 minutes (up to 10 minutes) after starting polymerization. A sudden rise (10 K-18 K) of temperature could be observed in most of the materials; soon afterwards the primary situation was reached again. The measured high temperatures should be considered to might be one of the factors, which lead to an affection of the pulp tissue.
In a prospective study the indications for root canal treatment and the complication rate were evaluated in 28 patients (51 teeth) with hemorrhagic diathesis. If strict precautions are taken, root canal treatment may be performed in patients with clotting disorders. The effort required to this end, however, seems to be unusually great, and long-term success cannot be guaranteed.
In a laboratory experiment a Mercury Vapor Analyzer was used to measure the mercury vapor concentration for 15 minutes during the filling of artificial cavities with amalgam. It was the object of this experiment to determine the effects of suctor type and condensation technique on the mercury concentration profile. When both suctors were used in the experimental "oral cavity" (420 m3), the mercury concentration was below 0.01 mg (Hg/m3. There was no statistically significant difference between mechanical and manual condensation.
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In a cross-sectional survey we obtained figures on the current state of periodontal health of 14 to 16-year-old pupils who attend different types of schools in Lippstadt, a town with a balanced social structure. A rate of 82% of gingivitis morbidity was found, including an average CPITN of 0.49. Nevertheless, only 43.8% of the examined periodontia showed signs of gingivitis. Analysis of the individual values showed marked differences related with age, sex and type of school.
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