ABSTRACT
The leather industry is one of the most polluting industries in the world due to the large amounts of waste following raw hide processing but also due to the high content of chemical substances present in leather waste. The main problem with chromium-tanned leather solid waste is related to the storage, due to the ability of chromium to leach into soil or water, and also owing to the high ability of trivalent chromium to oxidize to its toxic form, hexavalent chromium. The purpose of this article is to present the most current methods of chromium extraction from solid tanned leather waste in order to obtain non-polluting leather, which can constitute secondary raw material in new industrial processes. The extraction methods identified in the present study are based on acid/basic/enzymatic hydrolysis and substitution with the help of organic chelators (organic acids and organic acid salts). In addition, this study includes a comparative analysis of the advantages and disadvantages of each identified extraction method. At the same time, this study also presents alternative chromium extraction methods based on the combination of conventional extraction methods and ultrasound-assisted extraction.
ABSTRACT
BACKGROUND: Rathke's cleft cysts (RCC) are lesions that arise from Rathke's pouch. Though frequently incidental, resulting symptoms in a minority of cases are indicators for surgical resection, which may prove beneficial. OBJECTIVE: To characterize a cohort of surgically-resected RCC cases at Oregon Health & Science University; tabulate associated hormonal imbalances and symptoms, possible symptom reversal with surgery, determine recurrence risk; identify predictors of recurrence and headache improvement. METHOD: Electronic records of all RCC resected cases (from 2006-2016; 11 years) were retrospectively reviewed. Patients had been evaluated by one neuroendocrinologist using a uniform protocol. RESULTS: A pathological RCC diagnosis was established in 73 of 814 (9%) surgical pituitary cases. The RCC cohort was 77% (n = 56/73) female, mean age was 39.5 ± 14.9 years at first surgery, and at presentation headache was reported in 88% and visual defects/diplopia in 18% of patients. Initial RCC maximum diameter was 1.3 ± 0.7 cm. The most frequent hormonal deficit was cortisol; 24% of patients had a new adrenal insufficiency (AI) diagnosis, however, 36% also had AI at 3 months post-operatively. Mean follow up was 4.0 ± 4.5 years. Two-thirds of patients (41/62) had headache improvement 3 months post-operatively. Post-operative imaging revealed no residual cyst in 58% (38/65). In those patients with no residual RCC, 29% had recurrence and 71% had long lasting cure. From the 42% (27/65) of patients with residual cyst on post-operative imaging; 59% (16/27) remained stable, 26% (7/27) progressed and 15% (4/27) regressed. CONCLUSION: Symptomatic RCC present mostly in women, with a high proportion reporting headaches. Prevalence of AI at diagnosis is high. Surgery may not achieve adrenal axis recovery, but renders a high percentage of headache improvement. Approximately 25% of RCC will recur by 4 years postoperatively. Clinicians should cautiously screen patients with symptomatic RCC, regardless of lesion size for AI.