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The initial rate of Fe 2ϩ movement across the inner envelope membrane of pea (Pisum sativum) chloroplasts was directly measured by stopped-flow spectrofluorometry using membrane vesicles loaded with the Fe 2ϩ-sensitive fluorophore, Phen Green SK. The rate of Fe 2ϩ transport was rapid, coming to equilibrium within 3s. The maximal rate and concentration dependence of Fe 2ϩ transport in predominantly right-side-out vesicles were nearly equivalent to those measured in largely inside-out vesicles. Fe 2ϩ transport was stimulated by an inwardly directed electrochemical proton gradient across rightside-out vesicles, an effect that was diminished by the addition of valinomycin in the presence of K ϩ. Fe 2ϩ transport was inhibited by Zn 2ϩ , in a competitive manner, as well as by Cu 2ϩ and Mn 2ϩ. These results indicate that inward-directed Fe 2ϩ transport across the chloroplast inner envelope occurs by a potential-stimulated uniport mechanism.

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Achondroplasia is the most common of the heritable skeletal dysplasias. Cervico-medullary compression is a frequently encountered and potentially lethal neurological complication. Cervico-medullary decompression (CMD) at the foramen magnum is often employed to relieve the pressure on the emerging cervical cord. Given the inherent risks associated with major surgery, there has been a substantial debate regarding the best criteria for CMD. Our objectives for this study are to explore the quality of life of patients who had undergone CMD, and to assess whether surgery is associated with mortality and increased long-term morbidity. A Medical Outcome Study 36-item Short Form General Health Survey designed to evaluate eight general health concepts as well as achondroplasia-related issues, was administered to patients assessed in the neurosurgery department in Johns Hopkins Hospital between 1977 and 1998. One hundred and sixty-seven patients were eligible for inclusion. Forty-three could not be contacted, and two refused consent. One hundred and twenty-two patients were assessed. Fifty-six (46%) individuals had CMD and 66 (54%) did not. There was 1 case of mortality in the CMD group and 12 cases in the non-CMD group. In the non-CMD group, all deaths, as far as we know, were unrelated to cervico-medullary compression. In this cohort of surviving patients (n = 109), the quality of life of the 55 (50.5%) who had undergone CMD is comparable to that of the 54 (49.5%) who did not have surgery, controlled for age and sex. CMD is indicated for patients with achondroplasia with significant symptomatic foramen magnum compression. It can be life saving. It can abolish profound central apnea that may cause sudden death and alleviate neurological complications associated with damage of the significantly compressed spinal cord. With regards to long-term outcome evaluation, the quality of life of individuals with achondroplasia who had CMD is similar to those age- and sex-matched patients who did not have this surgery. Moreover, CMD, with all its inherent surgical risks, does not appear to be associated with higher mortality or increased long-term morbidity.