Adaptive changes in transmembrane transport and metabolism of triiodothyronine in perfused livers of fed and fasted hypothyroid and hyperthyroid rats

The transport and subsequent metabolism of triiodothyronine (T3) were studied in isolated perfused livers of euthyroid, hypothyroid, and hyperthyroid rats, both fed and 48-hour-fasted. T3 kinetics (transport and metabolism) during perfusion were evaluated by a two-pool model, whereas the metabolism of T3 was also investigated by determination of T3 breakdown products by chromatography of medium and bile. For comparison of groups, metabolism was corrected for differences in transport. Transport parameters in fed hypothyroid livers were not significantly changed as compared with euthyroid livers, whereas metabolism was decreased. In fed hyperthyroid livers, fractional transfer rate constants for influx (k21) and efflux (k12) were decreased and metabolism, corrected for differences in intracellular mass transfer, was increased. Furthermore, for transport in hyperthyroid livers it was shown that only total mass transfer (TMT) into the metabolizing liver compartment (not into the nonmetabolizing liver compartment) was decreased. Transport and metabolic parameters in fasted hypothyroid livers were decreased as compared with euthyroid fed livers. In fasted hyperthyroid livers, transport and metabolism were not significantly different as compared with that in euthyroid fed livers, so transport was increased versus hyperthyroid fed livers. It appeared therefore that fasting normalized the effects of hyperthyroidism on both the transport and metabolic processes of T3 in the liver. The present study demonstrates normal transport and decreased metabolism in livers of hypothyroid fed rats and decreased transport and increased metabolism in livers of hyperthyroid fed rats. In livers of hypothyroid fasted rats transport and metabolism were decreased, whereas in livers of hyperthyroid fasted rats transport and metabolism were not significantly different from that in euthyroid fed livers. These changes might favor tissue euthyroidism despite the altered thyroid and nutritional state, and can therefore be seen as adaptation mechanisms to these altered states at the tissue level

Relation between indicators for quality of occupational rehabilitation of employees with low back pain

OBJECTIVES: To assess if the implementation of guidelines for occupational rehabilitation of patients with low back pain by means of process variables--a set of objective criteria for technical performance and continuity of care--led to a better outcome in clinical and return to work variables. METHODS: The study group consisted of 59 patients with at least 10 days of sick leave because of low back pain. Univariate analyses as well as multiple logistic regression and Cox's regression analyses were performed to assess the relation between quality of care and outcome. RESULTS: Process indicators for technical competence, continuity of care, and total performance were all significantly related to satisfaction of employees. Continuity of care and total performance were significantly related to working status at 3 months, and time to return to work. None of the process indicators was related to pain or disability after 3 months follow up. Satisfaction was not related to any of the other outcome variables. This indicates that if guidelines for occupational rehabilitation are met, outcome is better. CONCLUSION: Quality of the process of care was related to outcome. Interventions of occupational physicians need improvement in the areas of continuity of care and communication with treating physicians. The effectiveness of an improved intervention should be studied in a subsequent randomised clinical trial.

Development and evaluation of a quality assessment instrument for occupational physicians

OBJECTIVES: To develop and apply a method for assessing the quality of the process of occupational health care for individual patients. METHODS: The scientific literature was studied to develop a method to assess the quality of the process of occupational rehabilitation for workers with low back pain. The method was applied to health care and university workers with low back pain who were rehabilitated by their occupational physicians. RESULTS: Assessment of quality of care is regarded as a four step approach. Firstly, guidelines should be developed and implemented. Secondly, indicators for quality and criteria to demarcate good and deviant quality were derived from the guidelines. Thirdly, a method for data collection was chosen. Finally, quality was scored. For occupational rehabilitation, there was some deviance from the guidelines for most cases, especially in continuity of care with a deviant rate of 47%. Other indicators deviated from 1.4%- 17.4%. Occupational physicians agreed on the relevance of the indicators and criteria, but for three indicators they evaluated the criteria as too rigid. They did not agree with their own performance scores in 66% of the deviant cases. CONCLUSION: Assessing the quality of the process of occupational health care with this method is an asset to present methods, but more specific criteria are needed for a more sensitive assessment.