[Tolerance to and dependence on opioids in isolated longitudinal muscle of guinea pig ileum. Validity of the muscle preparation as a receptor model for opioids (author's transl)]

Contractions evoked by electrical stimulation of isolated longitudinal muscle preparations of guinea pig ileum were inhibited by the addition of opioids in the order of morphine = methionine enkephalin greater than pentazocine pethidine. Incubation of the preparation in the medium containing opioids at 4 degrees C for 22 hr resulted in a tolerance to the inhibitory effect in morphine and pethidine but in the case of pentazocine and met-enkephalin tolerance did not develop under the conditions employed. The same treatment with morphine, pethidine and pentazocine resulted in the development of dependence as demonstrated by naloxone provoked contracture or increase in the height of contraction. Opiate and enkephalin receptors are known to be unevenly distributed in the ileum and a significant difference was also observed in the distribution patterns of both receptors. Distribution of the receptors did not parallel the effect of opioids, thereby indicating a multiplicity in receptors. However, under the conditions employed in the present experiments, our results reflect the in vivo effects of opioids, such as analgesic effect or tolerance and dependence liability, and the validity of this preparation for the evaluation of opioids was confirmed.

Hajdu-Cheney syndrome

Hadjdu-Cheney syndrome is a rare type of syndrome characterized by acro-osteolysis, dolichocephaly with multiple Wormian bones, absence of frontal sinuses and joint laxity. A case of this syndrome is presented. A histological study of the osteolytic lesion revealed destruction characterized by microfractures with a poor reparative process. It is postulated that an abnormality of osteoblast or osteoid function is the pathogenesis of this syndrome.

Radioimmunoassay of methionine enkephalin and interference by brain factor of immunoreactivity and opiate receptor binding activity

We developed a radioimmunoassay of methionine-enkephalin (met-enk) which was found to be highly specific to the peptide and 1 pmol was the detection limit. Interference by the following peptides was practically negligible; leucine-enkephalin, LAP- or CNBr-treated met-end, alpha- and beta-endorphins. Morphine and its congeners were totally inert. Measurement of met-enk in rat brain P2 fraction revealed besides met-enk, the presence of the factor which cross-reacted with the antiserum and also appeared to bind with the brain opiate receptor. Though the nature of the factor has not yet been characterized, it is suggested that for qualitative assessment of the tissue level of met-enk, a method to selectively inactivate either the peptide or the factor should be developed first.