Efficacy of a pediatric headache infusion center: A single-center experience.

OBJECTIVE: To evaluate the efficacy of a pediatric headache infusion center (HIC) in alleviating the symptoms and preventing future visits to the emergency department (ED). BACKGROUND: Headache is a common reason for visits to the pediatric ED. ED visits are associated with inordinate costs of care and are conceived by parents to be avoidable if adequate alternatives are available. An infusion center for acute treatment of intractable headache in children with chronic migraine may be an effective alternative to an ED visit. METHODS: This was a retrospective analysis of data from a single-center cohort of patients with a known history of chronic migraine, presenting to Dayton Children's HIC with an acute migraine from June 1, 2017 to June 1, 2020. Patients were treated according to established protocols divided into two pathways. Patient demographics, clinical characteristics, pre- and postinfusion pain scores, ED visits and inpatient admissions within 2 weeks of HIC visit, and ED visits 1 year prior and 1 year after the HIC visit were noted. RESULTS: A total of 297 HIC visits were analyzed from 201 patients. The HIC was effective in controlling symptoms with a significant reduction in pain score (median [interquartile range; IQR] 7.0 [2.0] preinfusion vs. 1.0 [2.0] postinfusion, p < 0.001). Only 25/297 (8.4%) patients came to the ED within 2 weeks of the HIC visit, and an even smaller number of patients (20/297, 6.7%) were admitted as inpatients within 2 weeks of the HIC visit. The number of ED visits was significantly reduced in the year after the HIC visit compared with the year prior (median [IQR] 1.0 [2.0] before vs. 0.0 [1.0] after, p < 0.001). CONCLUSION: A pediatric HIC is effective in alleviating the symptoms and preventing ED visits. These centers should be considered as standard of care at children's hospitals.

Peroxisomal catalases from the yeasts Pichia pastoris and Kluyveromyces lactis as models for oxidative damage in higher eukaryotes.

Catalases are among the main scavengers of reactive oxygen species (ROS) present in the peroxisome, thereby preventing oxidative cellular and tissular damage. In human, multiple diseases are associated with malfunction of these organelles, which causes accumulation of ROS species and consequently the inefficient detoxification of cells. Despite intense research, much remains to be clarified about the precise molecular role of catalase in cellular homeostasis. Yeast peroxisomes and their peroxisomal catalases have been used as eukaryotic models for oxidative metabolism, ROS generation and detoxification, and associated pathologies. In order to provide reliable models for oxidative metabolism research, we have determined the high-resolution crystal structures of peroxisomal catalase from two important biotechnology and basic biology yeast models, Pichia pastoris and Kluyveromyces lactis. We have performed an extensive functional, biochemical and stability characterization of both enzymes in order to establish their differential activity profiles. Furthermore, we have analyzed the role of the peroxisomal catalase under study in the survival of yeast to oxidative burst challenges combining methanol, water peroxide, and sodium chloride. Interestingly, whereas catalase activity was induced 200-fold upon challenging the methylotrophic P. pastoris cells with methanol, the increase in catalase activity in the non-methylotrophic K. lactis was only moderate. The inhibitory effect of sodium azide and ß-mercaptoethanol over both catalases was analyzed, establishing IC50 values for both compounds that are consistent with an elevated resistance of both enzymes toward these inhibitors. Structural comparison of these two novel catalase structures allows us to rationalize the differential susceptibility to inhibitors and oxidative bursts. The inherent worth and validity of the P. pastoris and K. lactis yeast models for oxidative damage will be strengthened by the availability of reliable structural-functional information on these enzymes, which are central to our understanding of peroxisomal response toward oxidative stress.

Structural and functional characterization of a highly stable endo-ß-1,4-xylanase from Fusarium oxysporum and its development as an efficient immobilized biocatalyst.

BACKGROUND: Replacing fossil fuel with renewable sources such as lignocellulosic biomass is currently a promising alternative for obtaining biofuel and for fighting against the consequences of climate change. However, the recalcitrant structure of lignocellulosic biomass residues constitutes a major limitation for its widespread use in industry. The efficient hydrolysis of lignocellulosic materials requires the complementary action of multiple enzymes including xylanases and ß-xylosidases, which are responsible for cleaving exo- and endoxylan linkages, that release oligocarbohydrates that can be further processed by other enzymes. RESULTS: We have identified the endo-ß-1,4-xylanase Xyl2 from Fusarium oxysporum as a promising glycoside hydrolase family 11 enzyme for the industrial degradation of xylan. To characterize Xyl2, we have cloned the synthetic optimized gene and expressed and purified recombinant Xyl2 to homogeneity, finally obtaining 10 mg pure Xyl2 per liter of culture. The crystal structure of Xyl2 at 1.56 Å resolution and the structure of a methyl-xylopyranoside Xyl2 complex at 2.84 Å resolution cast a highly detailed view of the active site of the enzyme, revealing the molecular basis for the high catalytic efficiency of Xyl2. The kinetic analysis of Xyl2 demonstrates high xylanase activity and non-negligible ß-xylosidase activity under a variety of experimental conditions including alkaline pH and elevated temperature. Immobilizing Xyl2 on a variety of solid supports enhances the enzymatic properties that render Xyl2 a promising industrial biocatalyst, which, together with the detailed structural data, may establish Xyl2 as a platform for future developments of industrially relevant xylanases. CONCLUSIONS: F. oxysporum Xyl2 is a GH11 xylanase which is highly active in free form and immobilized onto a variety of solid supports in a wide pH range. Furthermore, immobilization of Xyl2 on certain supports significantly increases its thermal stability. A mechanistic rationale for Xyl2's remarkable catalytic efficiency at alkaline pH is proposed on the basis of two crystallographic structures. Together, these properties render Xyl2 an attractive biocatalyst for the sustainable industrial degradation of xylan.