The proportions of cis−cis, cis−trans, and trans−trans isomers are in the ratio of 10.5 :6.2 :1. [cis-cis isomers ≈ 58% cis-trans isomers ≈ 36% trans-trans isomers ≈ 6%]. One of the three cis-cis structures is marketed as a single-isomer preparation, cisatracurium (trade name Nimbex); it has the configuration 1R, 2R, 1′R, 2′R at the four stereocentres. The beta-blocking drug Nebivolol has ten similar structures with 4 stereocentres and a plane of symmetry, but only two are presented in the pharmaceutical preparation. Intramuscular function parameters
ED95: the dose of any given intramuscular-blocking agent required to produce 95% suppression of muscle twitch (e.g., the abductor pollicis) response with balanced anesthesia
Clinical duration: difference in time between time of injection and time to 25% recovery from neuromuscular block
Train-of-Four (TOF) response: stimulated muscle twitch response in trains of four when stimuli are applied in a burst of four as opposed to a single stimulus, equal depression in depolarizing and fading response with non-depolarizing blocker.
Ornithine aminotransferase deficiency (also known as gyrate atrophy of the choroid and retina) is an inborn error of ornithine metabolism, caused by decreased activity of the enzyme ornithine aminotransferase. Biochemically, it can be detected by elevated levels of ornithine in the blood. Clinically, it presents initially with poor night vision, which slowly progresses to total blindness. It is believed to be inherited in an autosomal recessive manner. Approximately 200 known cases have been reported in the literature. The incidence is highest in Finland, estimated at 1:50,000.Research suggests there can be some adverse effect on muscles and also the brain. The cause of this is somewhat unclear but may relate to very low levels of creatine often found in this population. Treatment may include vitamin B6, lysine or dramatic dietary change to minimise arginine from patients diet. Research has indicated that these treatments may be somewhat effective in lowering ornithine blood concentration levels in some patients, either in combination or individually. Vitamin B6 has been found to be very effective in a small proportion of patients. Presentation
Quite often, the presenting symptom of ornithine aminotransferase (OAT) deficiency is myopia which progresses to night blindness. The onset of myopia is often in early childhood. Ophthalmological findings in affected individuals include constricted visual fields, posterior subcapsular cataracts (can begin in late teens), elevated dark adaptation thresholds and decreased or absent electroretinographic responses.