Is Metabolic Flexibility Altered in Multiple Sclerosis Patients?

Objectives

Metabolic flexibility is defined as ability to adjust fuel oxidation to fuel availability. Multiple sclerosis (MS) results in reduced muscle strength and exercise intolerance. We tested the hypothesis that altered metabolic flexibility contributes to exercise intolerance in MS patients.

Methods

We studied 16 patients (all on glatiramer) and 16 matched healthy controls. Energy expenditure (EE), and carbohydrate (COX) and lipid oxidation (LOX) rates were determined by calorimetry, before and after an oral glucose load. We made measurements either at rest (canopy device) or during 40 min low-grade (0.5 W/kg) exercise (metabolic chamber). We also obtained plasma, and adipose tissue and skeletal muscle dialysate samples by microdialysis to study tissue-level metabolism under resting conditions.

Results

At rest, fasting and postprandial plasma glucose, insulin, and free fatty acid levels did not differ between patients and controls. Fasting and postprandial COX was higher and LOX lower in patients. In adipose, fasting and postprandial dialysate glucose, lactate, and glycerol levels were higher in patients vs. controls. In muscle, fasting and postprandial dialysate metabolite levels did not differ significantly between the groups. During exercise, EE did not differ between the groups. However, COX increased sharply over 20 min in patients, without reaching a steady state, followed by an immediate decrease within the next 20 min and fell even below basal levels after exercise in patients, compared to controls.

Conclusions

Glucose tolerance is not impaired in MS patients. At rest, there is no indication for metabolic inflexibility or mitochondrial dysfunction in skeletal muscle. The increased adipose tissue lipolytic activity might result from glatiramer treatment. Autonomic dysfunction might cause dysregulation of postprandial thermogenesis at rest and lipid mobilization during exercise.     

Variation in enamel thickness within the genus Homo

Recent humans and their fossil relatives are classified as having thick molar enamel, one of very few dental traits that distinguish hominins from living African apes. However, little is known about enamel thickness in the earliest members of the genus Homo, and recent studies of later Homo report considerable intra- and inter-specific variation. In order to assess taxonomic, geographic, and temporal trends in enamel thickness, we applied micro-computed tomographic imaging to 150 fossil Homo teeth spanning two million years. Early Homo postcanine teeth from Africa and Asia show highly variable average and relative enamel thickness (AET and RET) values. Three molars from South Africa exceed Homo AET and RET ranges, resembling the hyper thick Paranthropus condition. Most later Homo groups (archaic European and north African Homo, and fossil and recent Homo sapiens) possess absolutely and relatively thick enamel across the entire dentition. In contrast, Neanderthals show relatively thin enamel in their incisors, canines, premolars, and molars, although incisor AET values are similar to H. sapiens. Comparisons of recent and fossil H. sapiens reveal that dental size reduction has led to a disproportionate decrease in coronal dentine compared with enamel (although both are reduced), leading to relatively thicker enamel in recent humans. General characterizations of hominins as having ‘thick enamel’ thus oversimplify a surprisingly variable craniodental trait with limited taxonomic utility within a genus. Moreover, estimates of dental attrition rates employed in paleodemographic reconstruction may be biased when this variation is not considered. Additional research is necessary to reconstruct hominin dietary ecology since thick enamel is not a prerequisite for hard-object feeding, and it is present in most later Homo species despite advances in technology and food processing.     

Persistence of Escherichia coli introduced into streambed sediments with goose,deer and bovine animal waste

Aims:  The focus of this work was to compare the survival of Escherichia coli introduced into streambed sediments from goose, deer and bovine faeces vs indigenous E. coli. Methods and Results:  The survival experiments were conducted in flow‐through chambers for 32 days using two sediments (mineral and organic) obtained from a first‐order creek in Maryland. Bovine, goose and deer faeces were collected fresh and diluted or enriched so that added E. coli and indigenous populations were equivalent. Escherichia coli and total coliforms were enumerated using the Colilert‐18 Quanti‐Tray system. Patterns of E. coli survival and inactivation rates were virtually identical for indigenous strains in both mineral and organic sediments. The addition of E. coli strains from bovine, goose or deer faeces had relatively little impact on final E. coli concentrations, with the exception of deer‐borne E. coli populations in the organic sediment. Conclusion:  These results indicate that indigenous sediment‐borne E. coli strains are generally, or more, persistent than those deposited into sediments, including wildlife. Significance and Impact of the Study:  This is the first study on the survival of E. coli originating from wildlife faeces, in sediments, as opposed to bovine faeces or laboratory‐cultured strains. As wildlife are likely to be the primary source of E. coli in most non agricultural watersheds, an understanding of the persistence of these strains is important to understanding microbial water quality.     

Investigation of the binding pocket of human hematopoietic prostaglandin (PG) D2 synthase (hH-PGDS): a tale of two waters

The inhibition of hH-PGDS has been proposed as a potential target for the development of anti-allergic and anti-inflammatory drugs. Herein we describe our investigation of the binding pocket of this important enzyme and our observation that two water molecules bind to our inhibitors and the enzyme. A series of compounds were prepared to the probe the importance of the water molecules in determining the binding affinity of the inhibitors to the enzyme. The study provides insight into the binding requirements for the design of potent hH-PGDS inhibitors.     

Thiadiazoles as new inhibitors of diacylglycerol acyltransferase type 1

A novel class of DGAT1 inhibitors containing a thiadiazole core has been discovered. Chemical optimization lead to inhibitors of human DGAT1 with an appropriate ADME profile and that show in vivo activity in target tissues.     

Viperin is an iron‐sulfur protein that inhibits genome synthesis of tick‐borne encephalitis virus via radical SAM domain activity

Viperin is an interferon‐induced protein with a broad antiviral activity. This evolutionary conserved protein contains a radical S‐adenosyl‐l ‐methionine (SAM) domain which has been shown in vitro to hold a [4Fe‐4S] cluster. We identified tick‐borne encephalitis virus (TBEV) as a novel target for which human viperin inhibits productionof the viral genome RNA. Wt viperin was found to require ER localization for full antiviral activity and to interact with the cytosolic Fe/S protein assembly factor CIAO1. Radiolabelling in vivo revealed incorporation of ⁵⁵Fe, indicative for the presence of an Fe‐S cluster. Mutation of the cysteine residues ligating the Fe‐S cluster in the central radical SAM domain entirely abolished both antiviral activity and incorporation of ⁵⁵Fe. Mutants lacking the extreme C‐terminal W361 did not interact with CIAO1, were not matured, and were antivirally inactive. Moreover, intracellular removal of SAM by ectopic expression of the bacteriophage T3 SAMase abolished antiviral activity. Collectively, our data suggest that viperin requires CIAO1 for [4Fe‐4S] cluster assembly, and acts through an enzymatic, Fe‐S cluster‐ and SAM‐dependent mechanism to inhibit viral RNA synthesis.     

Generation of “LYmph Node Derived Antibody Libraries” (LYNDAL) for selecting fully human antibody fragments with therapeutic potential

The development of efficient strategies for generating fully human monoclonal antibodies with unique functional properties that are exploitable for tailored therapeutic interventions remains a major challenge in the antibody technology field. Here, we present a methodology for recovering such antibodies from antigen-encountered human B cell repertoires. As the source for variable antibody genes, we cloned immunoglobulin G (IgG)-derived B cell repertoires from lymph nodes of 20 individuals undergoing surgery for head and neck cancer. Sequence analysis of unselected “LYmph Node Derived Antibody Libraries” (LYNDAL) revealed a naturally occurring distribution pattern of rearranged antibody sequences, representing all known variable gene families and most functional germline sequences. To demonstrate the feasibility for selecting antibodies with therapeutic potential from these repertoires, seven LYNDAL from donors with high serum titers against herpes simplex virus (HSV) were panned on recombinant glycoprotein B of HSV-1. Screening for specific binders delivered 34 single-chain variable fragments (scFvs) with unique sequences. Sequence analysis revealed extensive somatic hypermutation of enriched clones as a result of affinity maturation. Binding of scFvs to common glycoprotein B variants from HSV-1 and HSV-2 strains was highly specific, and the majority of analyzed antibody fragments bound to the target antigen with nanomolar affinity. From eight scFvs with HSV-neutralizing capacity in vitro, the most potent antibody neutralized 50% HSV-2 at 4.5 nM as a dimeric (scFv)₂. We anticipate our approach to be useful for recovering fully human antibodies with therapeutic potential.