Readership survey: success story.
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Biomedical subjects
Publications and source records attributed to L Thomas.
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Isolated human hepatocytes offer a unique way of studying the metabolism and mechanisms of action of drugs and toxic chemicals. Because of the irregular availability of human liver, a way of storing the hepatocytes until they can be conveniently used is required. Using rat and dog isolated hepatocytes, we have developed a procedure for cryopreserving hepatocytes in large numbers such as are needed for metabolism and toxicity studies. Hepatocytes were frozen in medium containing 10% dimethyl sulfoxide using a microcomputer-controlled freezing gradient and stored at -196 degrees C. Upon thawing, the total cell recovery for rat hepatocytes was 67%. Cell viability measured by trypan blue (TB) exclusion was 67%, 7-ethoxycoumarin (7-EOC) dealkylation 33%, and cytochrome P-450 75%, compared to fresh hepatocytes. With cryopreserved dog hepatocytes, the total cell recovery was 75%. TB exclusion was 62%, 7-EOC dealkylation 37%, and cytochrome P-450 68%, compared to fresh hepatocytes. The viability of cryopreserved hepatocyte preparations could be improved by density separation on Percoll giving a TB exclusion for rat hepatocytes of 85%, and 7-EOC dealkylation of 69% compared to fresh hepatocytes, with 67% of the viable cells recovered. Biphenyl was used as a substrate to measure integrated xenobiotic metabolizing activity by the hepatocytes. Total hydroxybiphenyl (OHB) formation, a mixed function oxygenase activity, was maintained in cryopreserved Percoll-treated rat hepatocytes at 86%, OHB glucuronide formation at 85%, and OHB sulfate formation at 20% of the values in fresh hepatocytes. In cryopreserved dog hepatocyte, total OHB formation was 39%, and OHB glucuronide and sulfate formation less than 10% of the values in fresh hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Based on a 15-year study, the indication of assisted ventilation at home is discussed. It depends on the seriousness of the C.R.I. (dyspnea, repeated acute failures, PaCO2 greater than or equal to 55 Torr). The only possible course is ventilation by tracheostomy. The best indication is represented by pure restrictive syndromes. On the contrary, the indication should be considered with extreme caution in obstructive syndromes.
With 200 patients during the last 15 years the daily use of apparatus and supervision modalities, as described in the present work, has shown that H.A.V. is entirely possible in tracheostomized C.R.I. patients. Rather strict conditions must be respected (as with hemodialysis at home) if H.A.V. is to be medically and materially successful. The expenses involved can vary greatly according to the medical and material management (choice of study material, economic maintenance, minimal oxygen consumption through proper adjustment...). Finally, the use of assisted ventilation requires a choice amont several adjustment possibilities which are still subject to evolution.
The following results have been obtained from a study of 118 tracheostomized patients ventilated at home: --Survival on the whole is generally prolonged. --The prognosis of tracheostomized subjects with restrictive syndrome is totally modified in length and quality when the patients are ventilated. --In the case of obstructive syndrome, the length and quality of survival are probably increased. However, it seems that assisted ventilation at home leads only to the disappearance of asphyxiating paroxysms and right cardiac failure. It does not seem to prevent the unrelenting evolution of the disease.
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