Robert P. Cowan

IN VIVO MAGNETIC RESONANCE SPECTROSCOPY OF HUMAN BRAIN : THE BIOPHYSICAL BASIS OF DEMENTIA

Nuclear magnetic resonance spectroscopy (MRS) in low and medium magnetic fields yields well-resolved natural abundance proton and decoupled phosphorus spectra from small (1-10 cc) volumes of brain in vivo in minutes. With this tool, neurochemical research has advanced through identification and non-invasive assay of specific neuronal--(N-acetylaspartate), glial (myo-inositol)--markers, energetics and osmolytes, and neurotransmitters (glutamate, GABA). From these simple measurements, several dozen disease states are recognized, including birth injury, and white matter and Alzheimer disease. Addition of stable isotopes of carbon (in man) or nitrogen (in experimental animals) has provided in vivo assays of enzyme flux through glucose transport, glycolysis, TCA-cycle, and the glutamine-glutamate-GABA system. Finally, a number of xenobiotics are recognized with heteronuclear NMR techniques. Together, these tools are having a major impact on neuroscience and clinical medicine. Through diagnosis and therapeutic monitoring, a new generation of in vivo metabolite imaging is expected with the advent of conforming RF coils and higher field NMR systems.

The morphology and biochemistry of nanostructures provide evidence for synthesis and signaling functions in human cerebrospinal fluid

BackgroundCerebrospinal fluid (CSF) contacts many brain regions and may mediate humoral signaling distinct from synaptic neurotransmission. However, synthesis and transport mechanisms for such signaling are not defined. The purpose of this study was to investigate whether human CSF contains discrete structures that may enable the regulation of humoral transmission.MethodsLumbar CSF was collected prospectively from 17 participants: with no neurological or psychiatric disease, with Alzheimers disease, multiple sclerosis, or migraine; and ventricular CSF from two cognitively healthy participants with long-standing shunts for congenital hydrocephalus. Cell-free CSF was subjected to ultracentrifugation to yield supernatants and pellets that were examined by transmission electron microscopy, shotgun protein sequencing, electrophoresis, western blotting, lipid analysis, enzymatic activity assay, and immuno-electron microscopy.ResultsOver 3,600 CSF proteins were identified from repeated shotgun sequencing of cell-free CSF from two individuals with Alzheimers disease: 25% of these proteins are normally present in membranes. Abundant nanometer-scaled structures were observed in ultracentrifuged pellets of CSF from all 16 participants examined. The most common structures included synaptic vesicle and exosome components in 30-200 nm spheres and irregular blobs. Much less abundant nanostructures were present that derived from cellular debris. Nanostructure fractions had a unique composition compared to CSF supernatant, richer in omega-3 and phosphoinositide lipids, active prostanoid enzymes, and fibronectin.ConclusionUnique morphology and biochemistry features of abundant and discrete membrane-bound CSF nanostructures are described. Prostaglandin H synthase activity, essential for prostanoid production and previously unknown in CSF, is localized to nanospheres. Considering CSF bulk flow and its circulatory dynamics, we propose that these nanostructures provide signaling mechanisms via volume transmission within the nervous system that are for slower, more diffuse, and of longer duration than synaptic transmission.

Prostaglandin D synthase isoforms from cerebrospinal fluid vary with brain pathology

Glutathione independent prostaglandin D synthase (Swissprot P41222, PTGDS) has been identified in human cerebrospinal fluid and some changes in PTGDS in relation to disease have been reported. However, little is known of the extent that PTGDS isoforms fluctuate across a large range of congenital and acquired diseases. The purpose of this study was to examine changes in PTGDS isoforms in such a population. Spinal fluid from 22 healthy study participants (normal controls) with no classifiable neurological or psychiatric diagnosis was obtained and PTGDS isoforms were identified by specific immunostaining and mass spectrometry after denaturing 2D gel electrophoresis. The PTGDS isoforms in controls consisted of five charge isoforms that were always present and a small number of occasional, low abundance isoforms. A qualitative survey of 98 different people with a wide range of congenital and acquired diseases revealed striking changes. Loss of the control isoforms occurred in congenital malformations of the nervous system. Gain of additional isoforms occurred in some degenerative, most demyelinating and vasculitic diseases, as well as in Creutzfeldt-Jakob disease. A retrospective analysis of published data that quantified relative amounts of PTGDS in multiple sclerosis, schizophrenia and Parkinson’s disease compared to controls revealed significant dysregulation. It is concluded that qualitative and quantitative fluctuations of cerebrospinal fluid PTGDS isoforms reflect both major and subtle brain pathophysiology.

Cerebrospinal Fluid Sodium Increases in Migraine

Background.—Pharmaceuticals with calcium‐ or sodium‐channel‐blocking activity have proven useful for migraine prophylaxis, and calcium channel, sodium transporter, and sodium channel gene mutations have been found in familial hemiplegic migraine. However, it is not known whether calcium or sodium homeostasis is altered in migraine.

Executive Function Changes before Memory in Preclinical Alzheimer’s Pathology: A Prospective, Cross-Sectional, Case Control Study

Background Early treatment of Alzheimer’s disease may reduce its devastating effects. By focusing research on asymptomatic individuals with Alzheimer’s disease pathology (the preclinical stage), earlier indicators of disease may be discovered. Decreasing cerebrospinal fluid beta-amyloid42 is the first indicator of preclinical disorder, but it is not known which pathology causes the first clinical effects. Our hypothesis is that neuropsychological changes within the normal range will help to predict preclinical disease and locate early pathology. Methods and Findings We recruited adults with probable Alzheimer’s disease or asymptomatic cognitively healthy adults, classified after medical and neuropsychological examination. By logistic regression, we derived a cutoff for the cerebrospinal fluid beta amyloid42/tau ratios that correctly classified 85% of those with Alzheimer’s disease. We separated the asymptomatic group into those with (n = 34; preclinical Alzheimer’s disease) and without (n = 36; controls) abnormal beta amyloid42/tau ratios; these subgroups had similar distributions of age, gender, education, medications, apolipoprotein-ε genotype, vascular risk factors, and magnetic resonance imaging features of small vessel disease. Multivariable analysis of neuropsychological data revealed that only Stroop Interference (response inhibition) independently predicted preclinical pathology (OR = 0.13, 95% CI = 0.04–0.42). Lack of longitudinal and post-mortem data, older age, and small population size are limitations of this study. Conclusions Our data suggest that clinical effects from early amyloid pathophysiology precede those from hippocampal intraneuronal neurofibrillary pathology. Altered cerebrospinal fluid beta amyloid42 with decreased executive performance before memory impairment matches the deposits of extracellular amyloid that appear in the basal isocortex first, and only later involve the hippocampus. We propose that Stroop Interference may be an additional important screen for early pathology and useful to monitor treatment of preclinical Alzheimer’s disease; measures of executive and memory functions in a longitudinal design will be necessary to more fully evaluate this approach.

Capillary Endothelial Na+, K+, ATPase Transporter Homeostasis and a New Theory for Migraine Pathophysiology

(Headache 2010;50:459‐478)

The place of corticosteroids in migraine attack management: A 65-year systematic review with pooled analysis and critical appraisal

Background and objectives Headaches recur in up to 87% of migraine patients visiting the emergency department (ED), making ED recidivism a management challenge. We aimed herein to determine the role of corticosteroids in the acute management of migraine in the ED and outpatient care. Methods Advanced search strategies employing PubMed/MEDLINE, Web of Science, and Cochrane Library databases inclusive of a relevant gray literature search was employed for Clinical Studies and Systematic Reviews by combining the terms “migraine” and “corticosteroids” spanning all previous years since the production of synthetic corticosteroids ca. 1950 until August 30, 2014. Methods were in accordance with MOOSE guidelines. Results Twenty-five studies (n = 3989, median age 37.5 years, interquartile range or IQR 35–41 years; median male:female ratio 1:4.23, IQR 1:2.1–6.14; 52% ED-based, 56% randomized-controlled) and four systematic reviews were included. International Classification of Headache Disorders criteria were applied in 64%. Nineteen studies (76%) indicated observed outcome differences favoring benefits of corticosteroids, while six (24%) studies indicated non-inferior outcomes for corticosteroids. Median absolute risk reduction was 30% (range 6%–48.2%), and 11% (6%–48.6%) for 24-, and 72-hour headache recurrence, respectively. Parenteral dexamethasone was the most commonly (56%) administered steroid, at a median single dose of 10 mg (range 4–24 mg). All meta-analyses revealed efficacy of adjuvant corticosteroids to various abortive medications—indicating generalizability. Adverse effects were tolerable. Higher disability, status migrainosus, incomplete pain relief, and previous history of headache recurrence predicted outcome favorability. Conclusions Our literature review suggests that with corticosteroid treatment, recurrent headaches become milder than pretreated headaches and later respond to nonsteroidal therapy. Single-dose intravenous dexamethasone is a reasonable option for managing resistant, severe, or prolonged migraine attacks.

CAM in the real world: you may practice evidence-based medicine, but your patients don't.

Complementary and Alternative Medicine (CAM) approaches are widely used among individuals suffering from headache. The medical literature has focused on the evidence base for such use and has largely ignored the fact that these approaches are in wide use despite that evidence base.

Does Exercise Make Migraines Worse and Tension Type Headaches Better

Many non-pharmacological treatments have been implicated in the treatment of primary headache, with exercise being a common recommendation. In this review we first provide an overview of the relationship between exercise and primary headaches. We then review the physiology of pain modulation, with focus on the endogenous opioids, endocannabinoids, and neuropeptides calcitonin gene-related peptide (CGRP) and brain-derived neurotrophic factor (BDNF), and their associations with primary headache and exercise. Finally, we summarize current literature evaluating effects of exercise on primary headache in an effort to understand the benefits and disadvantages of exercise in primary headaches.

Comparison of parenteral treatments of acute primary headache in a large academic emergency department cohort.

Objective The objective of this article is to compare acute primary headache patient outcomes in those initially treated with parenteral opiates or non-opiate recommended headache medications in a large academic medical emergency department (ED). Background Many acute primary headache patients are not diagnosed with a specific headache type and are treated with opiates and nonspecific pain medications in the ED setting. This is inconsistent with multiple expert recommendations. Methods Electronic charts were reviewed from 574 consecutive patients who visited the ED for acute primary headache (identified by chief complaint and ICD9 codes) and were treated with parenteral medications. Results Non-opiate recommended headache medications were given first line to 52.6% and opiates to 22.8% of all participants. Patients given opiates first had significantly longer length of stays (median 5.0 vs. 3.9 hours, p < 0.001) and higher rates of return ED visits within seven days (7.6% vs. 3.0%, p = 0.033) compared with those given non-opiate recommended medications in univariate analysis. Only the association with longer length of stay remained significant in multivariable regression including possible confounding variables. Conclusions Initial opiate use is associated with longer length of stay compared with non-opiate first-line recommended medications for acute primary headache in the ED. This association remained strong and significant even after multivariable adjustment for headache diagnosis and other possible confounders.