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Biomedical subjects

D A Scott

Publications and source records attributed to D A Scott.

At least 145 records · Page 8Linked to original sources
PubMed1985

Exogenous factors affecting the nails. Cosmetics, trauma, and occupational influences.

The external factors associated with nail disorders are multiple. Although not totally inclusive, this discussion has presented the more common cosmetic, traumatic, and industrial causes of nail disorders. Several common entities, such as the brown staining of fingernails in heavy tobacco smokers, have been omitted intentionally because little difficulty is encountered in determining their cause. Therefore, in evaluating a patient with abnormal nails, one should consider various external factors in addition to primary disease processes. Patch testing to determine if contact sensitivity is involved, in addition to a careful investigation of habits, employment, and exposures is mandatory.

Cosmetics↗
PubMed1984

Endodontic recall radiographs: how reliable is our interpretation of endodontic success or failure and what factors affect our reliability?

Three hundred thirty cases were selected from an endodontic practice. Postoperative and recall radiographs of each case were examined by four endodontists for an interpretation of treatment success or failure. One hundred eighteen cases were examined a second time by each endodontist. Initial analysis showed substantial inconsistency in both inter- and intraobserver interpretation. The cases were then categorized by average radiographic density differences within radiograph sets, anatomic location of the treated tooth, technical compatibility within radiograph sets, and by length of time between postoperative and recall radiographs. It appears that these factors do not affect reliability of success/failure interpretation.

Dental Pulp Cavity↗
PubMed1983

Effects of wheat, rice, corn, and soybean bran on 1,2-dimethylhydrazine-induced large bowel tumorigenesis in F344 rats.

This study was designed to determine the relative effects of four dietary brans on large bowel tumorigenesis in rats treated with 1,2-dimethylhydrazine (DMH). Four-week-old F344 rats were fed a 20% bran (either wheat, rice, corn, or soybean) semisynthetic diet or a no-fiber-added control diet for life. All rats except for one control diet for life. All rats except for one control group were infected with DMH (2SC doses; approximately 150 mg/kg body weight) at 8 and 10 weeks of age. Two additional groups were fed the control diet and then at 4 and 18 weeks, respectively, after the second DMH dose, were fed the wheat bran diet. All surviving rats were killed 9 months following the first DMH dose. Survival was increased in all groups receiving bran diets. Large bowel tumor incidences in the DMH group were as follows: control, 95%; wheat, 75%; rice 86%; corn, 100%; soybean, 84%; wheat after 4 weeks, 62% (lower than control group, p less than 0.05); wheat after 18 weeks, 84%. All but one of the DMH groups had approximately two tumors/tumor-positive rat; the corn group had four. The effect of bran on large bowel carcinogenesis appears to depend both on the source of bran and when it is fed in relation to tumor initiation.

1,2-Dimethylhydrazine↗
PubMed1978

Distribution of motoneurones to the neck muscles, biventer cervicis, splenius and complexus in the cat.

The distribution of motoneurones to the cat dorsal neck muscles biventer cervicis, splenius and complexus has been examined using the technique of retrograde horseradish peroxidase transport. A comparison was initially made of HRP uptake into motoneurones produced either by injecting HRP solution directly into a single neck muscle or by exposing the cut ends of motor nerves to an HRP solution. The injection of HRP into single neck muscles was found to produce widespread labelling of motoneurones presumably due to diffusion of HRP into adjacent muscles. For the examination of individual motoneurone pools the technique of cut nerve exposure was therefore used. Labelled neck muscle motoneurones ranged from 10-70 mu in diameter, but the majority of cells had diameters which were less than 40 mu. Most cells were located in the ventromedial nucleus and along the medial border of the ventral horn. In these regions there was considerable overlap between the motoneurone pools of the three neck muscles examined. In addition, some splenius motoneurones were located in the nucleus of the spinal accessory nerve. Labelled neck muscle motoneurones were also located in areas not usually considered to contain motoneurones such as the commissural and centrodorsal nuclei and in the ventral commissure.

Animals↗