Phenotypes and Endotypes in Asthma.

Asthma is a broadly encompassing diagnosis of airway inflammation with significant variability in presentation and response. Advances in molecular techniques and imaging have unraveled the delicate mechanistic tapestry responsible for the underlying inflammatory pathways in asthma. The elucidation of biomarkers and cellular components specific to these inflammatory pathways allowed for the categorization of asthma from generic phenotypes to more specific mechanistic endotypes, with two prominent subgroups emerging based on the level of Type 2 inflammation present - T2 high and T2 low (or non-T2). Sophisticated modeling and cluster analyses using a combination of clinical, physiologic, and biomarker parameters have permitted the identification of subendotypes within the broader T2 umbrella. This mechanistic-driven classification schema for asthma has dramatically altered the landscape of asthma management with the discovery and approval of targeted biologic therapies and has ushered in a new era of personalized precision medicine in asthma.

Reducing values: dinitrosalicylate gives over-oxidation and invalid results whereas copper bicinchoninate gives no over-oxidation and valid results.

A comparative study was made between two carbohydrate reducing value methods, a relatively old, highly alkaline, 3,5-dinitrosalicylic acid (DNSA) method and a relatively newer, low alkaline (pH 10.5), copper bicinchoninate (CuBic) method. Reducing values for a series of equimolar amounts of maltose-maltohexaose, isomaltose-isomaltohexaose, and cellobiose-cellohexaose were compared by the two methods. The DNSA method gave over-oxidation for equimolar amounts of all three of the oligosaccharide series. The amount of oxidation increased as the sizes of the oligosaccharides increased, giving inflated, inaccurate reducing values. The CuBic method gave constant reducing values, for equimolar amounts of the oligosaccharides, indicating that there was no over-oxidation, as the sizes of the oligosaccharides were increased. The two methods were used to determine the number average molecular weights (MWn) for six polysaccharides. The DNSA method was not able to determine the MWn for any of the polysaccharides tested due to the low sensitivity of the method, compared with the CuBic method that did not give over-oxidation and gave reasonable MWn values for all six of the polysaccharides tested.

Potent inhibition of starch-synthase by Tris-type buffers is responsible for the perpetuation of the primer myth for starch biosynthesis.

Mukerjea and Robyt [Carbohydr. Res. 2012, 352, 137-142] showed that a primer-free potato starch-synthase synthesized starch chains de novo, without the addition of a primer. A dichotomy arises as to why 61 studies from 1964 to the present have had to add a carbohydrate primer to obtain starch-synthase activity. All of these studies used 25-100 mM Tris, Bicine, or Tricine buffers. We have found that the Tris-type buffers completely inhibit starch-synthase at these concentrations. The addition of 10 mg/mL of the putative primers, glycogen and maltotetraose, gave a partial reversal of the inhibition, with glycogen being better than maltotetraose. It has been found that the Tris-type buffers form a complex with the ADPGlc substrate, removing it from the digest, causing the inhibition. The addition of the putative primers releases some of the ADPGlc from the complex, permitting it to act as a substrate for starch-synthase. The study definitively shows that the need for primers for starch-synthase by many investigators from 1964 to the present has been caused by Tris-type buffer inhibition that was partially reversed by putative primers. This has led to the perpetuation of the primer myth for the biosynthesis of starch chains by starch-synthase.