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Biomedical subjects

J S Shim

Publications and source records attributed to J S Shim.

24 records · Page 2Linked to original sources
PubMed1978

Colorimetric determination of arprinocid in feed.

An analytical method has been developed for the determination of arprinocid (9-(2-chloro-6-fluorophenylmethyl)-9H-purin-6-amine) in feed, based upon measurement of the absorbance of the diazo chromophore formed from a product of zinc reduction of the drug in acidic solution. The analyte is extracted from the feed into chloroform in the presence of a pH 7 phosphate buffer and isolated by adsorption chromatography on alumina, followed by partitioning between hexane and 0.15M HCl. The reduction product in the aqueous phase is then treated for colorimetric measurement. This procedure has been applied to determining 0.0010--0.0080% arprinocid in feed with a precision of less than 5% relative standard deviation near the middle of this concentration range. Of 32 feed additives examined, only zoalene and sulfamethazine were serious interferences. A study and discussion of several factors, e.g., reaction time, pH, and amount of zinc metal, that affect the analytical reactions are also included.

Absorption↗
PubMed1978

Further studies on the colorimetric determination of ronidazole in feeds.

A previously published colorimetric method for determining ronidazole, (1-methyl-5-nitro-imidazol-2-yl)methyl carbamate, can be used as an analytical technique for measuring the stability of this drug in medicated feeds. Although the color reaction per se is not selective, elution profiles of ronidazole and its demonstrated hydrolytic degradation product, 1-methyl-2-hydroxymethyl-5-nitroimidazole, show that the chromatographic separation used in the sample preparation efficiently isolates the drug from the degradation product. No interference was found in feeds containing 0.010% ronidazole and up to 0.010% degradation product.

Animal Feed↗
PubMedDate not supplied

Genu valgum in children with coxa vara resulting from hip disease.

Three patients with chronic hip disease and progressive coxa vera deformity also had an unrecognized compensatory ipsilateral genu valgum until the primary hip deformity had been corrected operatively. This unrecognized genu valgum may become subtly worse in a growing child because of lateralization of the mechanical axis of the lower extremity with respect to the knee joint. Operative correction of coxa vara acutely moves the mechanical axis farther laterally, causing the occult genu valgum to become clinically apparent. The genu valgum may subtly worsen over time in a growing child because of lateralization of the lower extremity mechanical axis with respect to the knee joint, with the resulting abnormal Hueter-Volkmann forces across the physis causing progressive genu valgum. Recognition of occult genu valgum before correcting coxa vara in children allows the surgeon the better to advise the family about the need for possible subsequent operations on the knee.

Adolescent↗
PubMedDate not supplied

An examination of the stress distribution in a soft-lined acrylic resin mandibular complete denture by finite element analysis.

PURPOSE: The aim of this study was to calculate the effect of a soft liner on stress distribution within a mandibular complete denture. Although patients have welcomed soft-lined complete dentures, early fracture is one of the main reasons for failure. To minimize and prevent prosthesis fracture, the understanding of the stress distribution within a prosthesis is important. MATERIALS AND METHODS: A 3-dimensional finite element model of a mandibular complete denture for a severely reduced residual alveolar ridge was constructed. The stress was calculated with linear static finite element analysis. The stress distribution in the soft-lined acrylic resin mandibular complete denture was compared with that of a conventional acrylic resin denture. The resulting stresses were displayed in terms of von Mises equivalent stress and the major principal stresses according to 5 different loading conditions: vertical loads in premolar, molar, and incisor regions; and oblique loads in premolar and molar regions. RESULTS: Oblique loads produced higher levels of stress in the labial notch regions than vertical loads, where tension was the primary mode of stress. Significantly reduced levels of von Mises stress were calculated in soft-liner layers under all loading conditions. Acrylic resin denture base portions, however, exhibited higher levels of von Mises stress in soft-lined complete dentures. CONCLUSION: Three-dimensional finite element analysis gave a realistic explanation of denture fractures and patient response to mandibular complete dentures with and without soft linings. Control of excess lateral occlusal contact might be helpful to reduce the probability of a fracture in soft-lined mandibular complete dentures.

Acrylic Resins↗
PubMedDate not supplied

Discoid lateral meniscus in children: clinical manifestations and morphology.

The authors investigated the correlation between the clinical manifestations and the morphology of discoid lateral meniscus. Thirty-eight children, age 5 to 17 years, with 39 cases of discoid lateral meniscus underwent an arthroscopic procedure and magnetic resonance imaging. The two most frequent preoperative clinical manifestations were pain and extension block. In 19 cases without surface tear, the most frequent clinical manifestation was extension block. In the sagittal magnetic resonance images, the mean thickness of the anterior portion of the discoid lateral meniscus (7.77 mm) in the group with extension block exceeded that (4.02 mm) in the group without extension block. Extension block was significantly more common in patients with the anterior hypertrophy type and the slab (anterior-posterior diffusely hypertrophic) type than in the posterior hypertrophy type by the modified Hall classification. As a result, extension block was significantly correlated with the morphology of the menisci. Also, the thickened anterior portion of the discoid lateral meniscus may be considered one of the mechanical factors that limit knee extension.

Adolescent↗