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Biomedical subjects

R A Finch

Publications and source records attributed to R A Finch.

51 records · Page 3Linked to original sources
PubMed1979

Alterations in lipid metabolism of developing muscle cells in culture.

Embryonic chick muscle cells in the infused (myoblast) and fused (myotube) states differentially incorporate [3H]palmitic acid into their cellular lipids. Myoblasts incorporated [3H]palmitic acid 6--7-fold greater than myotubes in the triglyceride fraction. The endogenous triglyceride levels, however, were similar for the two developmental stages indicating increased triglyceride turnover in the myoblast compared to that of the myotube. Myotubes showed an increased incorporation of [3H]palmitic acid into sphingomyelin compared to myoblasts. Myoblasts and myotubes had a similar phospholipid composition. The data indicate that fusion is characterized by a decrease in triglyceride turnover possibly reflecting a shift from oxidative to glycolytic metabolism to coincide with the fusion process.

Animals↗
PubMed1979

Treatment of Goodpasture's syndrome with immunosuppression and plasmapheresis.

A 14-year-old boy with Goodpasture's syndrome induced by anti-glomerular-basement-membrane (gmb) antibody exhibited declining renal function, in association with a progressive increase in the level of serum anti-GBM antibody. Treatment with prednisone, cyclophosphamide, and plasmapheresis was associated with rapid disappearance of the serum anti-GMB antibody and temporary stabilization of renal function.

Adolescent↗
PubMed1978

Graft avulsion: an unreported complication of axillofemoral bypass grafts.

A case of avulsion of a unilateral axillofemoral Dacron bypass graft 3 weeks after insertion is reported. Surface measurements on healthy volunteers suggest that when the thoracolumbar spine is in full lateral flexion the length of the graft may increase by up to 21 per cent. Such movements should be restricted during the early postoperative period.

Aged↗
PubMed1978

The lack of an inhibitory effect of hyaluronate on chondrogenesis in chick limb-bud mesoderm cells grown in culture.

The effect of hyaluronate on chondrogenesis in cultures of chick limb-bud mesoderm cells, derived from stage 20--21, 23--24 and 26 embryos grown at different cell densities and in 3 different culture media, was studied. The results show that hyaluronate at a concentration of 500 microgram/ml, does not consistently produce an inhibition of chondrogenesis in cultures of stage 20--21, 23--24 or 26 limb-bud mesoderm cells in contrast to what has been reported by Toole et al. (1972). It was demonstrated that under optimal conditions, stage 26 cells grown in the absence of hyaluronate do not form as many cartilage colonies in culture as do cells from stage 20--21 or 23--24 embryos. It was determined that culture medium composed of Eagle's MEM supplemented with 7% horse serum, 3% fetal calf serum and 5% 10-day chick embryo extract supported chondrogenesis significantly better than Ham's F-12 supplemented with 10% fetal calf serum. Our results suggest that the inhibition of chondrogenesis by hyaluronate reported earlier is most likely due to the sub-optimal conditions of growth medium, cell density and embryonic stage than to the hyaluronate treatment.

Animals↗
PubMedDate not supplied

FETAX interlaboratory validation study: phase III--Part 1 testing.

The Frog Embryo Teratogenesis Assay-Xenopus (FETAX) is a 96-h whole embryo developmental toxicity screening assay that can be used in ecotoxicology and in detecting mammalian developmental toxicants when an in vitro metabolic activation system is employed. A standardized American Society for Testing and Materials (ASTM) guide for the conduct of FETAX has been published, along with a companion atlas that aids in embryo staging and identifying malformations. As part of the ASTM process, a three-phase interlaboratory validation study was undertaken to evaluate the repeatability and reliability of FETAX. Seven different participants collaborated in the study. In Phase I, FETAX proved to be more repeatable and reliable than many bioassays. However, some excessive variation was observed in a few laboratories. An initial lack of assay experience by some technicians caused variation. Phase II showed far less intra- and interlaboratory variability than Phase I. Non-teratogens showed the most consistent results, while more variability was observed for the two teratogens tested. Interlaboratory coefficient of variation values for all endpoints ranged from 7.3 to 54.7. Phase III--Part 1, using coded samples and test concentration ranges selected by each laboratory, showed results similar to Phase I. Analysis of the causes of variation suggested that some technicians judged some embryos to be malformed while others consistently judged similar embryos as normal. Concentration ranges tested by some of the laboratories varied greatly and a new protocol for selecting concentrations for initial testing was written to reduce variation from this source. Testing to date suggests that FETAX is as repeatable and reliable as other standard bioassays.

Aminopropionitrile↗
PubMedDate not supplied

Phase III interlaboratory study of FETAX. Part 3. FETAX validation using 12 compounds with and without an exogenous metabolic activation system.

FETAX (Frog Embryo Teratogenesis Assay-Xenopus) is a 96-h whole-embryo developmental toxicity screening assay that can be used in ecotoxicology and in detecting mammalian developmental toxicants when an in vitro metabolic activation system is employed. A standardized American Society for Testing and Materials (ASTM) guide for the conduct of FETAX has been published, along with a companion atlas that helps in embryo staging and in identifying malformations. As part of the ASTM process, an interlaboratory validation study was undertaken to evaluate the repeatability and reliability of FETAX and to evaluate the potential teratogenic hazard of 12 compounds. Three different laboratories participated in the study. All three participating laboratories had extensive experience with the assay. FETAX intralaboratory and interlaboratory variability, as judged by coefficients of variation, were very low. Potential teratogenic hazard was evaluated using two major criteria from FETAX experiments employing metabolic activation systems (MAS). These were the teratogenic index TI (TI = 96-h lc(50)/96-h ec(50) (malformation)) and the minimum concentration that inhibits growth (MCIG). A compound was considered teratogenic by this criterion when the MCIG was significantly different from controls at concentrations below the 30% level of the MAS 96-h lc(50). Based on the results of this and other studies, a decision table was constructed in order to evaluate additional studies. Severity of malformations caused, especially near the MAS 96-h ec(50) (malformation), were also evaluated. Four compounds were non-teratogenic but two compounds were clearly teratogenic. The remaining six compounds were ranked as equivocal teratogens. The results were discussed in light of the difficulty of producing an adequate decision table. FETAX proved to yield repeatable and reliable data as long as care was taken during range-finding and technicians were adequately trained. The MAS was essential in using FETAX to predict developmental hazard in mammals, and still requires further development.

Acetates↗
PubMedDate not supplied

Initial interlaboratory validation study of FETAX: phase I testing.

An interlaboratory validation study was undertaken to evaluate the repeatability and reliability of the Frog Embryo Teratogenesis Assay-Xenopus (FETAX), which is a whole embryo developmental toxicity screening assay. A three-phase experimental program with seven participants was carried out. Phase I was a training and protocol evaluation phase where the identity of the three test materials was known. Hydroxyurea, isoniazid and 6-aminonicotinamide were tested in Phase I. Because the chemicals has been tested previously in FETAX, the same concentrations needed to establish the 96-h median lethal concentration (LC50) and the concentration inducing malformations in 50% of the surviving embryos (EC50) were used by all laboratories. The results of Phase I are presented in this report, and FETAX has proved to be as repeatable and reliable as many other bioassays. Some excess variation was observed in individual laboratories. Some of this variation may have been due to training difficulties. One change in protocol design necessitated by this study was the use of 6-aminonicotinamide as a reference toxicant. While 6-aminonicotinamide provided excellent concentration-response data in most laboratories, the protocol was written too strictly based on historical FETAX data. Phases II and III are currently in progress.

6-Aminonicotinamide↗
PubMedDate not supplied

Evaluation of a reproductive toxicity assay using Xenopus laevis: boric acid, cadmium and ethylene glycol monomethyl ether.

Cadmium (Cd), boric acid (BA) and ethylene glycol monomethyl ether (EGME) were evaluated for reproductive and developmental toxicity in Xenopus laevis. Eight reproductively mature adult male and eight superovulated female Xenopus laevis were exposed to at least five separate sublethal concentrations of each material via the culture water for a period of 30 days. Four respective pairs were mated and the offspring evaluated for developmental effects; an evaluation of reproductive status was performed on the remaining four specimens. Ovary pathology, oocyte count, oocyte maturity and maturation capacity (germinal vesicle breakdown, GVBD) and necrosis were evaluated in the female, whereas testis pathology, sperm count, dysmorphology and motility were studied in the male. Based on this assessment, each test material exerted reproductive toxicity in Xenopus laevis, but with varying potencies. Adult female exposure to Cd and EGME particularly, and to a lesser extent to BA, resulted in transgenerational toxicity to the developing progeny. Further, this model appears to be a useful tool in the initial assessment and prioritization of potential reproductive toxicants for further testing.

Abnormalities, Drug-Induced↗