Biomedical subjects
Publications and source records attributed to S Z Chen.
Crystals of alpha-momorcharin were obtained by vapour phase diffusion. The crystal belongs to the space group R3, with unit cell constants a = b = 131.3 A, c = 39.5 A. There is one alpha-momorcharin molecule in the asymmetric unit; a data set at 3 A has been collected.
The posterior tibial flap is a type C fasciocutaneous flap from the medial calf with the posterior tibial vascular bundle as its pedicle. Most of the skin perforators, 1 to 3 in number, can be found in the middle third of the leg, with an average diameter of 0.8 mm and an average length of 22 mm. The posterior tibial artery ranges between 1.5 and 2.0 mm in diameter, although it is absent in 8 percent of limbs. Since the saphenous nerve is taken with the flap, this is an innervated flap. The flap can be transferred as a free flap or a pedicled flap. The reversed-flow pedicled flap has an average pedicle length of 8 cm. The posterior tibial flap is a reliable, large, thin, innervated flap and can be raised with the patient supine. Case reports are presented of six patients who received a free flap transfer and of one patient who received a reversed-flow pedicled flap. There were two cases of heel ulcerations, two crushed hands, one chronic ulceration and osteomyelitis of the tibia, one burn contracture of the neck, and one salvage flap for diabetic gangrene of the hand.
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A few reports have documented overdoses of vincristine sulfate. The present report describes our experience with serious complications of a vincristine overdose in an 18-year-old female who had methotrexate-resistant invasive mole. The patient received VAC therapy as the second line chemotherapy after 2 courses of MTX therapy. In the 6th course of VAC therapy, she was given 5 consecutive daily doses of VCR by mistake. On the 5th day of this VAC therapy, she showed the following toxic symptoms: abdominal pain, lumbago, insomnia, bleeding tendency, absence of motor reflex, leukopenia, and paralytic ileus. These symptoms led to realization of the VCR overdose. Leucovorin calcium administration and supportive treatment were carried out. Although it was difficult to evaluate the efficacy of leucovorin calcium on the vincristine toxic symptoms, she recovered and was discharged on the 36th hospital day.
Normal human fibroblast cells have not been reported to escape crisis--that is, they die after about 24 doublings in culture. We have been studying the growth properties of skin fibroblast cells from persons in families with familial adenopolyposis of the colon (FAP). An individual hemizygous at the FAP locus will develop hyperplasia of the colonic epithelium followed by colonic polyps, both at an early age. Polyps themselves still retain a single functional FAP allele. A mutation or deletion in this allele in a polyp is hypothesized to lead to further loss of growth control; thus, a tumor is formed. We found that the in vitro life-span of skin fibroblast cells from FAP individuals and from some asymptomatic children were markedly extended when compared with normal individuals.
To test the hypothesis that alpha-methylnorepinephrine (MNE) is the principal active metabolite involved in the hypotensive action of alpha-methyldopa (MD), we determined the relationship between MD's depressor response and tissue levels of MD metabolites in critical sites. After administration of 250 mg/kg MD intraperitoneally to Sprague-Dawley rats (300 +/- 50 g), we studied both heart (left ventricle) and brainstem MD, MNE and endogenous NE levels using HPLC with electrochemical detection. We also measured systolic blood pressure before and during MD (25-250 mg/kg i.p.) treatment using the tail-cuff method. Our results indicate that: (1) peak MD hypotensive response was dose-dependent. (2) Central NE concentration was maximally reduced by 2 hours whereas peripheral NE was maximally reduced by 18 hours. The maximal hypotensive effect was closer to the central peak distribution of MNE than MD. (3) The MD concentrations and NE concentrations in brainstem and heart showed counterclockwise hysteresis while MNE showed clockwise hysteresis. Furthermore, the area of MNE hysteresis in brainstem was larger than that of NE. We conclude that MD's depressor effect can not be completely explained by the assumption that MNE is the sole active metabolite; alternate metabolites or mechanisms would appear to be operative.
We have cloned into Escherichia coli the genes for 38 type-II bacterial modification methyltransferases. The clones were isolated by selecting in vitro for protectively modified recombinants. Most of the clones modify their DNA fully but a substantial number modify only partially. In approximately one-half of the clones, the genes for the corresponding endonucleases are also present. Some of these clones restrict infecting phages and others do not. Clones carrying endonuclease genes but lacking methyltransferase genes have been found, in several instances, to be viable.
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To clarify the diagnostic criteria of occulted or transient hyperprolactinemia, the resting prolactin level and the prolactin secreting capacity of normal women, which were tested with a 500 micrograms of TRH injection, were compared with those of patients with occulted hyperprolactinemia. Results revealed that: resting levels of prolactin in normal women were 13.4 +/- 4.4 ng/ml (mean +/- S.D.) in the follicular phase and 13.4 +/- 5.6 ng/ml in the luteal phase, which overlapped those of occulted hyperprolactinemia. the prolactin secreting capacity of occulted hyperprolactinemia was significantly greater than that of the normal women. These results indicated that it was impossible to distinguish the occulted hyperprolactinemia from the normal by the measuring the resting prolactin level, but possible by the evaluating the prolactin secreting capacity. If the serum prolactin was more than 150 ng/ml at 15 min. after TRH administration, occulted hyperprolactinemia was strongly suggested.
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