ABSTRACT
Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. Here we design a Pt(II) pincer-type material with selective absorptive and emissive responses to methanol and water. The yellow anhydrous form converts reversibly on a subsecond timescale to a red hydrate in the presence of parts-per-thousand levels of atmospheric water vapour. Exposure to methanol induces a similarly-rapid and reversible colour change to a blue methanol solvate. Stable smart coatings on glass demonstrate robust switching over 104 cycles, and flexible microporous polymer membranes incorporating microcrystals of the complex show identical vapochromic behaviour. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantum-chemical modelling, we provide a complete microscopic picture of the switching mechanism. We discuss how this multiscale design approach can be used to obtain new compounds with tailored VOC selectivity and spectral responses.
ABSTRACT
INTRODUCTION: Chronic mild endogenous glucocorticoid excess has been shown to cause bone loss and to increase fracture risk in both post-menopausal and premenopausal women. Currently, it is unclear if patients with subclinical Cushing's syndrome (SCS) with osteoporosis or osteopenia may benefit from antiresorptive treatment and the type of therapy to be given. OBJECTIVE: This pilot randomized study was aimed at evaluating the effects of 12-month im administration of clodronate (100 mg every week) on vertebral and femoral bone mineral density (BMD), bone turnover markers and on subjective pain in premenopausal women with SCS due to adrenal incidentalomas. METHODS: Forty-six women (age, 43.1+/-7.7 yr) with SCS due to adrenal incidentaloma and osteoporosis/osteopenia were randomized to receive clodronate plus supplement of Calcium (500 mg daily) and Vitamin D3 (800 mg daily) (group 1, no.=23) or supplements only (group 2, no.=23). Both groups were similar in terms of age, body mass index, cortisol levels, BMD values, and bone turnover markers. All of the women were re-evaluated after 12 months. RESULTS: After 12 months of treatment, in group 1, a significant increase in lumbar BMD occurred (p=0.04), while bone turnover markers decreased by about one third (p<0.05). In group 2, bone turnover markers did not change and BMD values slightly decreased (p=ns). The differences in bone turnover markers and in lumbar BMD between the two groups were significant (p<0.05, all). No new vertebral fracture occurred in group 1, while in group 2 the spine radiographies revealed 2 new fractures and a worsening of two pre-existent fractures. An improvement in subjective back pain, assessed by visual analogue scale pain score was observed in group 1 (from 4.3+/-2.7 to 2.9+/-2.0; p<0.05) but not in group 2 (from 4.4+/-3.1 to 4.2+/-3.4; p=ns). No significant changes occurred in cortisol secretion or clinical picture of the SCS during the study. CONCLUSIONS: Intramuscular administration of clodronate effectively increased lumbar BMD values, preserved bone mass at the femoral neck, stabilized vertebral fracture index, and decreased subjective back pain in pre-menopausal women with SCS. Since the untreated group continued to lose bone, antiresorptive treatment should be considered in patients with SCS, according to the prevision of surgical treatment, prevalent fractures, BMD values, age, concomitant morbidities, and desire for pregnancy.
