Vitrification of aqueous cryoprotectant mixtures is essential in cryopreservation of proteins and other biological samples. We report systematic measurements of critical cryoprotective agent (CPA) concentrations required for vitrification during plunge cooling from T=295 K to T=77 K in liquid nitrogen. Measurements on fourteen common CPAs including alcohols (glycerol, methanol, isopropanol), sugars (sucrose, xylitol, dextrose, trehalose), PEGs (ethylene glycol, PEG 200, PEG 2 000, PEG 20 000), glycols (DMSO, MPD), and salt (NaCl) were performed for volumes ranging over four orders of magnitude from ∼ nL to 20 µL, and covering the range of interest in protein crystallography. X-ray diffraction measurements on aqueous glycerol mixtures confirm that the polycrystalline-to-vitreous transition occurs within a span of less than 2% w/v in CPA concentration, and that the form of polycrystalline ice (hexagonal or cubic) depends on CPA concentration and cooling rate. For most of the studied cryoprotectants, the critical concentration decreases strongly with volume in the range from 5 µL to 0.1 µL, typically by a factor of two. By combining measurements of the critical concentration versus volume with cooling time versus volume, we obtain the function of greatest intrinsic physical interest: the critical CPA concentration versus cooling rate during flash cooling. These results provide a basis for more rational design of cryoprotective protocols, and should yield insight into the physics of glass formation in aqueous mixtures.

Few data are available for assessing the outcomes of bariatric surgery for patients who have undergone orthotopic liver transplantation (OLT). The University of Minnesota bariatric surgery database and transplant registry were retrospectively reviewed to identify patients who had undergone OLT and then open Roux-en-Y gastric bypass (RYGB) surgery between 2001 and 2009. Comorbidity-appropriate laboratory values, body mass indices (BMIs), histopathology reports, and immunosuppressive regimens were collected. Seven patients were identified with a mean age of 55.4 6 8.64 years and a mean follow-up of 59.14 6 41.49 months from the time of RYGB. The mean time between OLT and RYGB was 26.57 6 8.12 months. The liver disease etiologies were hepatitis C (n 5 4), jejunoileal bypass surgery (n 5 1), hemangioendothelioma (n 5 1), and alcoholic cirrhosis (n 5 1). There were 2 deaths for patients with hepatitis C 6 and 9 months after bariatric surgery due to multiple-organ dysfunction syndrome and metastatic esophageal squamous carcinoma, respectively. One patient with hepatitis C required a reversal of the RYGB because of malnutrition and an inability to tolerate oral intake. Four of the 7 patients had type 2 diabetes mellitus (T2DM), 4 had hypertension, and 6 patients had dyslipidemia. All patients were on immunosuppressive medications, but only 4 were on corticosteroids. Glycemic control was improved in all surviving patients with T2DM. The mean BMI was 34.27 6 5.51 kg/m 2 before OLT and 44.34 6 6.08 kg/m 2 before RYGB; it declined to 26.47 6 5.53 kg/m 2 after RYGB. In conclusion, in this case series of patients undergoing RYGB after OLT, we observed therapeutic weight loss, improved glycemic control, and improved high-density lipoprotein levels in the presence of continued dyslipidemia. RYGB may have contributed to the death of 1 patient due to multiple-organ dysfunction syndrome. Liver

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One of the hypotheses for the development of familial amyotrophic lateral sclerosis (ALS) is that mutations in the superoxide dismutase 1 enzyme lead to aberrant properties of the copper within the active site of the enzyme which then causes increased oxidative damage. The lipophilic metal chelators DP-109 and DP-460 which chelate calcium, copper, and zinc were tested in the G93A-transgenic ALS mouse model. Both compounds significantly extended survival, DP-109 (5 mg/kg/day) by 10%, DP-460 (10 mg/kg/day) by 9%. While the effect on survival was relatively small, chelator treatment also improved motor performance, dramatically reduced cell loss in the lumbar spinal cord and decreased reactive astrocytosis and microgliosis. Markers of oxidative damage, tumor necrosis factor (TNF)-a and a-synuclein were reduced in the lumbar spinal cord of G93A mice treated with DP-109 or DP-460 as compared with vehicle-treated animals. Furthermore, the treatment induced protein expression of the transcription factor hypoxia inducible factor-1a and mRNA levels of vascular endothelial growth factor as a corresponding target gene. In line with previous studies using metal chelators in the G93A animal model, our results suggest that these compounds have neuroprotective capacities in ALS.