Treatment of persistent post-concussive symptoms after mild traumatic brain injury: a systematic review of cognitive rehabilitation and behavioral health interventions in military service members and veterans.

Increased prevalence of traumatic brain injury (TBI) has been associated with service members and veterans who completed combat deployments in support of Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF). Management of persistent post-concussive symptoms (PCS) has been a challenge to healthcare providers throughout the Military and Veterans Healthcare Systems, as well as civilian healthcare providers, due in part to the chronic nature of symptoms, co-occurrence of behavioral health disorders such as depression, Posttraumatic Stress Disorder (PTSD), and substance use disorders, and fear of a potential stigma associated with psychiatric diagnoses and behavioral health treatment(s). This systematic review examined non-pharmacologic behavioral health interventions and cognitive rehabilitation interventions for PCS in military service members and veterans with a history of mild TBI (mTBI). Six electronic databases were searched with specific term limitations, identifying 121 citations. Ultimately, 19 articles met criteria for inclusion in this systematic review. Studies were broadly categorized into four subtypes: psychoeducational interventions, cognitive rehabilitation, psychotherapeutic approaches, and integrated behavioral health interventions for PCS and PTSD. The review provides an update of the empirical evidence for these four types of interventions for PCS in active duty service members and veterans. Recommendations for future research are discussed, including the need to expand and improve the limited evidence basis on how to manage persistent post-concussive symptoms in this population.

Nutrition intervention for migraine: a randomized crossover trial.

BACKGROUND: Limited evidence suggests that dietary interventions may offer a promising approach for migraine. The purpose of this study was to determine the effects of a low-fat plant-based diet intervention on migraine severity and frequency. METHODS: Forty-two adult migraine sufferers were recruited from the general community in Washington, DC, and divided randomly into two groups. This 36-week crossover study included two treatments: dietary instruction and placebo supplement. Each treatment period was 16 weeks, with a 4-week washout between. During the diet period, a low-fat vegan diet was prescribed for 4 weeks, after which an elimination diet was used. Participants were assessed at the beginning, midpoint, and end of each period. Significance was determined using student's t-tests. RESULTS: Worst headache pain in last 2 weeks, as measured by visual analog scale, was initially 6.4/10 cm (SD 2.1 cm), and declined 2.1 cm during the diet period and 0.7 cm during the supplement period (p=0.03). Average headache intensity (0-10 scale) was initially 4.2 (SD 1.4) per week, and this declined by 1.0 during the diet period and by 0.5 during the supplement period (p=0.20). Average headache frequency was initially 2.3 (SD 1.8) per week, and this declined by 0.3 during the diet period and by 0.4 during the supplement period (p=0.61). The Patient's Global Impression of Change showed greater improvement in pain during the diet period (p<0.001). CONCLUSIONS: These results suggest that a nutritional approach may be a useful part of migraine treatment, but that methodologic issues necessitate further research. TRIAL REGISTRATION: Clinicaltrials.gov, NCT01699009 and NCT01547494.

Saturated and trans fats and dementia: a systematic review.

Cognitive disorders of later life are potentially devastating. To estimate the relationship between saturated and trans fat intake and risk of cognitive disorders. PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for studies reporting saturated or trans fat intake and incident dementia, Alzheimer's disease (AD), or mild cognitive impairment (MCI) or cognitive decline. Only observational studies met the inclusion criteria: 4 for AD or other dementias, 4 for MCI, and 4 for cognitive decline. Saturated fat intake was positively associated with AD risk in 3 of 4 studies, whereas the fourth suggested an inverse relationship. Saturated fat intake was also positively associated with total dementia in 1 of 2 studies, with MCI in 1 of 4 studies, and with cognitive decline in 2 of 4 studies. Relationships between trans fat intake and dementia were examined in 3 reports with mixed results. Several, although not all, prospective studies indicate relationships between saturated and trans fat intake and risk of cognitive disorders.

Knockout mouse models of insulin signaling: Relevance past and future.

Insulin resistance is a hallmark of type 2 diabetes. In an effort to understand and treat this condition, researchers have used genetic manipulation of mice to uncover insulin signaling pathways and determine the effects of their perturbation. After decades of research, much has been learned, but the pathophysiology of insulin resistance in human diabetes remains controversial, and treating insulin resistance remains a challenge. This review will discuss limitations of mouse models lacking select insulin signaling molecule genes. In the most influential mouse models, glucose metabolism differs from that of humans at the cellular, organ, and whole-organism levels, and these differences limit the relevance and benefit of the mouse models both in terms of mechanistic investigations and therapeutic development. These differences are due partly to immutable differences in mouse and human biology, and partly to the failure of genetic modifications to produce an accurate model of human diabetes. Several factors often limit the mechanistic insights gained from experimental mice to the particular species and strain, including: developmental effects, unexpected metabolic adjustments, genetic background effects, and technical issues. We conclude that the limitations and weaknesses of genetically modified mouse models of insulin resistance underscore the need for redirection of research efforts toward methods that are more directly relevant to human physiology.

Visualizing ribosome biogenesis: parallel assembly pathways for the 30S subunit.

Ribosomes are self-assembling macromolecular machines that translate DNA into proteins, and an understanding of ribosome biogenesis is central to cellular physiology. Previous studies on the Escherichia coli 30S subunit suggest that ribosome assembly occurs via multiple parallel pathways rather than through a single rate-limiting step, but little mechanistic information is known about this process. Discovery single-particle profiling (DSP), an application of time-resolved electron microscopy, was used to obtain more than 1 million snapshots of assembling 30S subunits, identify and visualize the structures of 14 assembly intermediates, and monitor the population flux of these intermediates over time. DSP results were integrated with mass spectrometry data to construct the first ribosome-assembly mechanism that incorporates binding dependencies, rate constants, and structural characterization of populated intermediates.

Kinetic cooperativity in Escherichia coli 30S ribosomal subunit reconstitution reveals additional complexity in the assembly landscape.

The Escherichia coli 30S ribosomal subunit self-assembles in vitro in a hierarchical manner, with the RNA binding by proteins enabled by the prior binding of others under equilibrium conditions. Early 16S rRNA binding proteins also bind faster than late-binding proteins, but the specific causes for the slow binding of late proteins remain unclear. Previously, a pulse-chase monitored by quantitative mass spectrometry method was developed for monitoring 30S subunit assembly kinetics, and here a modified experimental scheme was used to probe kinetic cooperativity by including a step where subsets of ribosomal proteins bind and initiate assembly prior to the pulse-chase kinetics. In this work, 30S ribosomal subunit kinetic reconstitution experiments revealed that thermodynamic dependency does not always correlate with kinetic cooperativity. Some folding transitions that cause subsequent protein binding to be more energetically favorable do not result in faster protein binding. Although 3(') domain primary protein S7 is required for RNA binding by both proteins S9 and S19, prior binding of S7 accelerates the binding of S9, but not S19, indicating there is an additional mechanistic step required for S19 to bind. Such data on kinetic cooperativity and the presence of multiphasic assembly kinetics reveal complexity in the assembly landscape that was previously hidden.

The effect of ribosome assembly cofactors on in vitro 30S subunit reconstitution.

Ribosome biogenesis is facilitated by a growing list of assembly cofactors, including helicases, GTPases, chaperones, and other proteins, but the specific functions of many of these assembly cofactors are still unclear. The effect of three assembly cofactors on 30S ribosome assembly was determined in vitro using a previously developed mass-spectrometry-based method that monitors the rRNA binding kinetics of ribosomal proteins. The essential GTPase Era caused several late-binding proteins to bind rRNA faster when included in a 30S reconstitution. RimP enabled faster binding of S9 and S19 and inhibited the binding of S12 and S13, perhaps by blocking those proteins' binding sites. RimM caused proteins S5 and S12 to bind dramatically faster. These quantitative kinetic data provide important clues about the roles of these assembly cofactors in the mechanism of 30S biogenesis.

Stable isotope pulse-chase monitored by quantitative mass spectrometry applied to E. coli 30S ribosome assembly kinetics.

Stable isotope mass spectrometry has become a widespread tool in quantitative biology. Pulse-chase monitored by quantitative mass spectrometry (PC/QMS) is a recently developed stable isotope approach that provides a powerful means of studying the in vitro self-assembly kinetics of macromolecular complexes. This method has been applied to the Escherichia coli 30S ribosomal subunit, but could be applied to any stable self-assembling complex that can be reconstituted from its component parts and purified from a mixture of components and complex. The binding rates of 18 out of the 20 ribosomal proteins have been measured at several temperatures using PC/QMS. Here, PC/QMS experiments on 30S ribosomal subunit assembly are described, and the potential application of the method to other complexes is discussed. A variation on the PC/QMS experiment is introduced that enables measurement of kinetic cooperativity between proteins. In addition, several related approaches to stable isotope labeling and quantitative mass spectrometry data analysis are compared and contrasted.

Quantitative ESI-TOF analysis of macromolecular assembly kinetics.

The Escherichia coli small (30S) ribosomal subunit is a particularly well-characterized model system for studying in vitro self-assembly. A previously developed pulse-chase monitored by quantitative mass spectrometry (PC/QMS) approach to measuring kinetics of in vitro 30S assembly suffered from poor signal-to-noise and was unable to observe some ribosomal proteins. We have developed an improved LC-MS based method using quantitative ESI-TOF analysis of isotope-labeled tryptic peptides. Binding rates for 18 of the 20 ribosomal proteins are reported, and exchange of proteins S2 and S21 between bound and unbound states prevented measurement of their binding kinetics. Multiphasic kinetics of 3' domain proteins S7 and S9 are reported, which support an assembly mechanism that utilizes multiple parallel pathways. This quantitative ESI-TOF approach should be widely applicable to study the assembly of other macromolecular complexes and to quantitative proteomics experiments in general.

Quantitative analysis of isotope distributions in proteomic mass spectrometry using least-squares Fourier transform convolution.

Quantitative proteomic mass spectrometry involves comparison of the amplitudes of peaks resulting from different isotope labeling patterns, including fractional atomic labeling and fractional residue labeling. We have developed a general and flexible analytical treatment of the complex isotope distributions that arise in these experiments, using Fourier transform convolution to calculate labeled isotope distributions and least-squares for quantitative comparison with experimental peaks. The degree of fractional atomic and fractional residue labeling can be determined from experimental peaks at the same time as the integrated intensity of all of the isotopomers in the isotope distribution. The approach is illustrated using data with fractional (15)N-labeling and fractional (13)C-isoleucine labeling. The least-squares Fourier transform convolution approach can be applied to many types of quantitative proteomic data, including data from stable isotope labeling by amino acids in cell culture and pulse labeling experiments.

An isotope labeling strategy for quantifying the degree of phosphorylation at multiple sites in proteins.

A procedure for determining the extent of phosphorylation at individual sites of multiply phosphorylated proteins was developed and applied to two polyphosphorylated proteins. The protocol, using simple chemical (Fischer methyl-esterification) and enzymatic (phosphatase) modification steps and an accessible isotopic labeling reagent (methyl alcohol-d(4)), is described in detail. Site-specific phosphorylation stoichiometries are derived from the comparison of chemically identical but isotopically distinct peptide species analyzed by microspray liquid chromatography-mass spectrometry (microLC-MS) using a Micromass Q-TOF2 mass spectrometer. Ten phosphorylation sites were unambiguously identified in tryptic digests of both proteins, and phosphorylation stoichiometries were determined for eight of the ten sites using the isotope-coded strategy. The extent of phosphorylation was also estimated from the mass spectral peak areas for the phosphorylated and unmodified peptides, and these estimates, when compared with stoichiometries determined using the isotope-coded technique, differed only marginally (within approximately 20%).