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R W Ott

Publications and source records attributed to R W Ott.

18 recordsLinked to original sources
PubMed1996

Repeated sequences from the Arabidopsis thaliana genome function as enhancers in transgenic tobacco.

Sixteen segments of Arabidopsis thaliana DNA that function as enhancers in transgenic tobacco plants were isolated using the pROA97 enhancer cloning vehicle and library transformation of Nicotiana tabacum. The sequences were compared for AT content, homology, repeated motifs, and expression pattern in transgenic N. tabacum. The sequences were average with respect to the AT content of A. thaliana DNA. They could be placed into seven homology groups. Five of the sequences are single-copy sequences. The remaining eleven sequences represent two homology groups. Homology Group I contains seven sequences with minor differences. Homology Group II contains four sequences with minor differences. Two repeated motifs were identified (5'-CCTCT-3' and 5'-AAGGAT-3'). Both repeated motifs are found in other plant enhancers, and in the promoter region of the cauliflower mosaic virus 35S gene. In the 35S gene TATA region, the motifs can form two alternative stem-loop structures. The TATATAA sequence is located in the loop region of both stem-loop structures.

Arabidopsis↗
PubMed1991

[Studies on the perception of periodontal stimuli].

The stimulation of the periodontium causes a reflex response of the jaw muscles and at the same time a perceptive reaction of the central nervous system. The aim of our study was to develop a method for the objective assessment of the subjective perception experienced after stimulating the periodontium. Seven healthy volunteers took part in these experiments in the course of which mechanical stimuli (2.5 N, 750 microseconds) were applied perpendicular to the tooth, thus leading to a stimulation of the periodontium. Sensory evoked potentials of the periodontium (SEP-PA) elicited from the EEG served as an objective measure of perception. A computerized analysis of the data thus obtained allows an assessment of the change in perception following repeated periodontal stimulation at different rates.

Electroencephalography↗
PubMed1991

[Interocclusal clearance and changes in occlusal position in dentate and edentulous jaws. 1].

Six methods of assessing the resting position were evaluated in this study of 22 patients with teeth and 10 edentulous patients. None of these methods yielded reproducible results. The resting position is not a fixed, constant value, but depends on the method used. As could be shown by means of the standard deviation the method used to determine the resting position has a considerable influence on the distribution, and hence on the margin of error when the vertical relation is being determined. Small ranges of distribution were achieved: a) by means of the closest speaking distance when the patient spoke the numbers from 60 to 70 in a natural voice, b) after prompt relaxation of the lower jaw when the patients were asked to relax their jaws, c) when the interocclusal distance was measured after the mouth had been opened a little and the lips subsequently touched again lightly. Since there is little difference in the values with any one patient the three methods can be recommended for practical use.

Adult↗
PubMed1991

[The influence of brushing methods on wedge-shaped defects].

By experimentally brushing 20 teeth vertically to the tooth axis under a pressure of 2 N only lesions in cementum or dentine could be obtained. There was no case in which enamel was damaged by our brushing experiments. Therefore, defects appearing clinically cannot be explained by wrong tooth brushing techniques. There were several parallel lesions (similar to a saw blade) to be found as well as confluent hard tissue losses. Both indicate the direction of the movement of the tooth brush. The smallest defect to be measured in coronal-apical direction was 2.25 mm, the biggest 6.7 mm. The depth of the defects ranged front 239.9 microns to 493.2 microns. A correlation between Vicker's hardness and substance abrasion could not be proved, nor was the clinical appearance of wedge-shaped defects to be achieved by means of our experimental device. The formation of enamel defects cannot be explained by mere mechanical abrasion due to tooth brushing. In our opinions the formation of wedge-shaped defects implies a multicausal process.

Dental Enamel↗
PubMed1990

Enhancer sequences from Arabidopsis thaliana obtained by library transformation of Nicotiana tabacum.

In this paper we report on the use of a bidirectional enhancer cloning vehicle to isolate and characterize new enhancer sequences from Arabidopsis thaliana. A library of A. thaliana genomic Sau3A segments was constructed in Escherichia coli in the binary plasmid enhancer cloning vehicle pROA97. The T-DNA based vector carries abbreviated TATA regions from the cauliflower mosaic virus 35S transcription unit upstream of two genes. The library was transferred via triparental mating into Agrobacterium tumefaciens. The neomycin phosphotransferase II gene was used for selection of kanamycin-resistant transformed tobacco callus cells. Approximately 1100 transgenic plants were regenerated and assayed for expression of the E. coli beta-glucuronidase (GUS) gene in leaves, stems, roots, or seeds. Plasmids carrying putative enhancer sequences were rescued from the genomes of transgenic plants and the cloned sequences were assayed for enhancer function in genetic selection experiments. Plants were regenerated from the kanamycin-resistant calli obtained in the secondary transformation experiments. Histochemical analysis of GUS activity in the leaf, stem, and root tissues of transgenic plants showed a variety of expression patterns. The DNA sequences are presented of five Arabidopsis segments which confer enhancer function.

Base Sequence↗
PubMed1990

[Electronic measurements of the masticatory muscles. 1: Methods of recording].

The application of surface electromyography as an aid in diagnosing craniomandibular dysfunction requires that pathological or treatment-induced changes of the EMG be distinguished with sufficient probability from random variations due to methodological or biological reasons. It was the aim of this study to determine the range of variability of elevator muscle EMG, to find experimental methods for improving reproducibility, and to establish evaluation procedures that allow the recognition of treatment-induced effects in the EMG even in the presence of great random variations. For this we measured the voltage/tension relation of the elevator muscles of 42 persons in the range of 20 to 500 N on up to 20 different days under constant experimental conditions. The majority of measurements revealed a non-linear correlation between EMG activity and resulting force, hence second order polynomials proved to be more appropriate than straight lines for representing the activity/tension correlation. Muscle activity was found to vary randomly from day to day within each individual. These fluctuations appeared as varying axis intersections, initial slopes and curvatures which are the determinants of the voltage/tension curves. In ten selected subjects random fluctuations were significantly higher when electrodes were repositioned by palpation of the muscle belly than with the aid of tattoos.

Bite Force↗
PubMed1990

[Electronic measurements of the masticatory muscles. 2: Interpretation of activity changes in the masticatory muscles].

In part II, a method is described which reduced the variations of the three determinants of the voltage/tension curves to the fluctuation of only one three dimensional variable. A way to estimate three dimensional regions for the fluctuations is shown. For a given level of significance, limits can be calculated that allow us to decide whether differences between post- and pre-treatment measurements are random or due to treatment.

Electromyography↗
PubMed1989

[Masticatory forces and maximum jaw closure forces of complete denture wearers before and after bite opening].

The maximum jaw closure forces and the masticatory forces during the comminution of soft and though food were measured with changing vertical dimensions. The maximum jaw closure force was reduced by a mean 25% in all patients after the vertical dimension had been increased. Significant reductions in the masticatory forces were found only on the working side with the forces decreasing rather during the chewing of soft than tough food. Thus, in chewing sour drops the average masticatory force was 32.9 N as against 46.6 N, whereas in chewing bread it dropped to 21.3 N as against 42.8 N. The study showed that increasing the vertical dimension in endentulous patients up to an interocclusal clearance of 0 mm resulted in a functional impairment of speech and mastication and, above all, in sore spots and inflammations of the mucosa.

Bite Force↗
PubMed1989

[Cuspid protection and muscular reaction].

In an epidemiological study we found bilateral cuspid guidance in only 4, and unilateral cuspid guidance in 3 patients out of 247 patients examined. This suggest that cuspid guidance is a rare form of articulation. In the experimental part of this study the electric activity of the masseter and anterior temporal muscles was measured during empty mastication before and after the canines were treated with build-ups in a patient group with muscular and TMJ problems and matched against the results obtained in a control group of 10 healthy probands. Apart from the mean muscle activity also the path of excursion was recorded. Both values were combined in activity/path diagrams providing information on the muscular response to different forms of occlusion. Existing balancing contacts in mediotrusion, for instance, may produce high activities. With cuspid build-ups allowing correct cuspid guidance the patients with muscular and TMJ problems were symptom-free after just three days. After approx. one year the patients and the probands were recalled for a follow-up check. These and other results are discussed.

Cuspid↗
PubMed1987

Expression of the Bacillus subtilis polC gene in Escherichia coli.

We have cloned a 14 kb DNA segment containing the coding sequence (polC) for DNA polymerase III (PolIII) from the Bacillus subtilis chromosome. The plasmid carrying the sequence, pRO10, directs the synthesis of the 160 kDa PolIII protein and three additional polypeptides in Escherichia coli maxicells from strain CSR603. A set of deletion derivatives of pRO10 was constructed in vitro. The location of the PolIII coding sequence and the direction of transcription through the polC gene were determined by analysis of the truncated polypeptides observed in extracts of CSR603 transformants. Two HindIII segments subcloned from pRO10 were found to contain promoter sequences which function in E. coli and in vegetative phase B. subtilis cells. The location of the promoter sequence was determined with respect to the polC gene. The B. subtilis polC gene did not complement the temperature-sensitive defect of an E. coli PolIII mutant (dnaE486). The presence of the complete B. subtilis polC gene on a multicopy plasmid inhibited the growth of E. coli cells.

Bacillus subtilis↗
PubMed1986

Cloning and characterization of the polC region of Bacillus subtilis.

The polC gene of Bacillus subtilis is defined by five temperature-sensitive mutations and the 6-(p-hydroxyphenylazo)-uracil (HPUra) resistance mutation azp-12. Biochemical evidence suggests that polC codes for the 160-kilodalton DNA polymerase III. A recombinant plasmid, p154t, was isolated and found to contain the azp-12 marker and one end of the polC gene (N. C. Brown and M. H. Barnes, J. Cell. Biochem. 78 [Suppl.]: 116, 1983). The azp-12 marker was localized to a 1-kilobase DNA segment which was used as a probe to isolate recombinant lambda phages containing polC region sequences. A complete polC gene was constructed by in vitro ligation of DNA segments derived from two of the recombinant phages. The resulting plasmid, pRO10, directed the synthesis of four proteins of 160, 76, 39, and 32 kilodaltons in Escherichia coli maxicells. Recombination-deficient (recE) B. subtilis PSL1 containing pRO10 produced an HPUra-resistant polymerase III activity which was lost when the strain was cured of pRO10. In vivo, the HPUra resistance of the plasmid-encoded polymerase III appeared to be recessive to the resident HPUra-sensitive polymerase III enzyme.

Bacillus subtilis↗
PubMed1981

Human squamous cell carcinoma. Establishment and characterization of new permanent cell lines.

Squamous cell carcinoma is the most common of human cancers, and yet because it is poorly represented by cultured cell lines, little is known about the characteristic cell biology and the cell-surface antigenic phenotypes of such tumors. To develop a continuously available source of squamous cell carcinoma for repeated and reproducible serologic analysis and for better understanding of its biologic characteristics, tissue culture methods and nude mice were used to establish new cell lines of squamous carcinoma. Special media, serum supplements from several sources, and methods of handling fresh tissue specimens were all examined as a means of improving the survival of tumor cell lines. Several new cell lines were established. Features characteristic of a squamous cell origin, eg, microvilli, desmosomes, tonofilaments, and the squamous cell differentiation antigen (pemphigus antigen), were found. The clinical course of disease in individual donor patients has been examined.

Aged↗