Biomedical subjects
Publications and source records attributed to J C Roberts.
Fracture toughness, critical strain energy release rate, and critical stress intensity factor were determined for experimental and commercial restorative resins. A composite resin had lower resistance to crack initiation than an unfilled acrylic resin. The data were consistent with surface failure observed in single-pass wear studies of these resins.
Antral mucosal diaphragm is uncommon, and presents with manifestations of obstruction to the pyloric outlet. The diagnosis is usually established only by gastrotomy. Excision of the diaphragm or pylorophasty affords permanent cure and unnecessary partial gastrectomy should be avoided.
A giant smooth muscle tumour of the stomach was excised in a 58-year-old man. Although small leiomyomas are not rare, the giant gastric leiomyoma is not common, and may present diagnostic and operative difficulties. It is an essentially benign tumour, unlike the "bizarre" leiomyoma or leiomyoblastoma.
The sterol compositions of three oceanic jellyfish have been determined using gas chromatographic mass spectrometric techniques involving the use of two separate gas chromatographic column systems. The components in overlapping peaks have been identified by comparison of the mass spectra of peaks in the two column systems using subtractive techniques. A mid-water animal, Periphylla periphylla, was found to contain a very complex and unusual sterol profile including rare 5alpha-stanols, whereas two other oceanic jellyfish Pelagia noctiluca and Atolla wyvillei contained similar mixtures of delta5 sterols to those previously isolated from coastal species.
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Advances in knowledge about atherosclerosis in the past 25 years were discussed. Areas of disagreement and agreement were identified. A concept of HOST-DOSE-TIME was introduced for the skeptical analysis of past, present, and future observation and treatment of atherosclerosis.
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Some recent liquid phases for gas-liquid chromatography with improved thermostability have been evaluated for their use in the gas-liquid chromatographic-mass spectrometric (GC-MS) analysis of the complex mixtures of sterol trimethylsilyl ethers obtained, often in small amounts, from marine organisms. A combination of Dexsil 300 GC, SE-30 "ultraphase" and Silar 5CP is recommended for use in this technique because of the excellent separating efficiency and the very low substrate bleed. GC-MS analysis of the sterol trimethylsilyl ethers obtained from the cockle Cerastoderma edule has established the identity and relative proportions of the eleven sterols present.
Two cases of pleural effusion are described, both of which were associated with pancreatitis of traumatic origin. It is suggested that in some cases of unexplained pleural effusion, concomitant pancreatitis should be sought as a possible cause.
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