Faculty Bibliography

OBJECTIVE:CD16+ /CD163+ macrophages (MΦ)s and microglia accumulate in the brains of patients with HIV encephalitis (HIVE), a neuropathological correlate of the most severe form of HIV-associated neurocognitive disorders (HAND), HIV-associated dementia (HIV-D). Recently, we found that some parenchymal microglia in brain of HIV+ subjects without encephalitis (HIV/noE) but with varying degrees of neurocognitive impairment express CD16 and CD163, even in the absence of detectable virus production. To further our understanding of microglial activation in HIV, we investigated expression of specific genes by profiling parenchymal microglia from archival brain tissue of patients with HIVE, HIV/noE, and HIV- controls. METHODS:Single-population microarray analyses were performed on ∼2,500 laser capture microdissected CD163+ , CD16+ or CD68+ MΦs/microglia per case, using terminal continuation (TC) RNA amplification and a custom-designed array platform. RESULTS:Several classes of microglial transcripts in HIVE and HIV/noE, were altered, relative to HIV- subjects, including factors related to cell stress, immune activation, and apoptosis. Additionally, several neurotrophic factors are reduced in HIV infection, suggesting an additional mechanism of neuropathogenesis. The majority of transcripts altered in HIVE displayed intermediate changes in HIV/noE. INTERPRETATION/CONCLUSIONS:Our results support the notion that microglia contribute to the maintenance of brain homeostasis and their potential loss of function in the context of chronic inflammation contributes to neuropathogenesis. Furthermore, they indicate the utility of profiling MΦs/microglia to increase our understanding of microglia function, as well as ascertain alterations in specific pathways, genes, and, ostensibly, encoded proteins that may be amenable to targeted treatment modalities in diseases affecting the brain.

OBJECTIVES: The aim of this study was to compare testicular metabolite concentrations between fertile control subjects and infertile men. MATERIALS AND METHODS: Single voxel proton magnetic resonance spectroscopy ((1)H-MRS) was performed in the testes with and without water suppression at 3 T in 9 fertile control subjects and 9 infertile patients (8 with azoospermia and 1 with oligospermia). In controls only, the T1 and T2 values of water and metabolites were also measured. Absolute metabolite concentrations were calculated using the unsuppressed water signal as a reference and correcting for the relative T1 and T2 weighting of the water and metabolite signals. RESULTS: Testicular T1 values of water, total choline, and total creatine were 2028 +/- 125 milliseconds, 1164 +/- 105 milliseconds, and 1421 +/- 314 milliseconds, respectively (mean +/- standard deviation). T2 values were 154 +/- 11 milliseconds, 342 +/- 53 milliseconds, and 285 +/- 167 milliseconds, respectively. Total choline concentration was lower in patients (mean, 1.5 mmol/L; range, 0.9-2.1 mmol/L) than controls (mean, 4.4 mmol/L; range, 3.2-5.7 mmol/L; P = 4 x 10(-)(5)). Total creatine concentration was likewise reduced in patients (mean, 1.1 mmol/L; range, undetectable -2.7 mmol/L) compared with controls (mean, 3.6 mmol/L; range, 2.5-4.7 mmol/L; P = 1.6 x 10(-)(4)). The myo-inositol signal normalized to the water reference was also lower in patients than controls (P = 4 x 10(-)(5)). CONCLUSIONS: Testicular metabolite concentrations, measured by proton spectroscopy at 3 T, may be valuable as noninvasive biomarkers of spermatogenesis.

BACKGROUND:Oligomeric forms of amyloid-β (Aβ) and tau are increasing being recognized as key toxins in the pathogenesis of Alzheimer's disease (AD). METHODS:We developed a novel monoclonal antibody (mAb), GW-23B7, that recognizes β-sheet secondary structure on pathological oligomers of neurodegenerative diseases. RESULTS:The pentameric immunoglobulin M kappa chain (IgMκp) we developed specifically distinguishes intra- and extracellular pathology in human AD brains. Purified GW-23B7 showed a dissociation constant in the nanomolar range for oligomeric Aβ and did not bind monomeric Aβ. In enzyme-linked immunosorbent assays, it recognized oligomeric forms of both Aβ and hyperphosphorylated tau. Aged triple-transgenic AD mice with both Aβ and tau pathology infused intraperitoneally for 2 months showed IgMκp in the soluble brain homogenate, peaking at 24 h postinoculation. Treated mice exhibited significant cognitive rescue on radial arm maze testing compared with vehicle control-infused mice. Immunohistochemically, treatment resulted in a significant decrease of extracellular pathology. Biochemically, treatment resulted in significant reductions of oligomeric forms of Aβ and tau. CONCLUSIONS:These results suggest that GW-23B7, an anti-β-sheet conformational mAb humanized for clinical trials, may be an effective therapeutic agent for human AD.

Topographic maps are a basic organizational feature of nervous systems, and their construction involves both spatial and temporal cues. A recent study reports a novel mechanism of topographic map formation which relies on the timing of axon initiation.

Motor output varies along the rostro-caudal axis of the tetrapod spinal cord. At limb levels, ∼60 motor pools control the alternation of flexor and extensor muscles about each joint, whereas at thoracic levels as few as 10 motor pools supply muscle groups that support posture, inspiration, and expiration. Whether such differences in motor neuron identity and muscle number are associated with segmental distinctions in interneuron diversity has not been resolved. We show that select combinations of nineteen transcription factors that specify lumbar V1 inhibitory interneurons generate subpopulations enriched at limb and thoracic levels. Specification of limb and thoracic V1 interneurons involves the Hox gene Hoxc9 independently of motor neurons. Thus, early Hox patterning of the spinal cord determines the identity of V1 interneurons and motor neurons. These studies reveal a developmental program of V1 interneuron diversity, providing insight into the organization of inhibitory interneurons associated with differential motor output.

Developmental ethanol exposure is a well-known cause of lifelong cognitive deficits, behavioral hyperactivity, emotional dysregulation, and more. In healthy adults, sleep is thought to have a critical involvement in each of these processes. Our previous work has demonstrated that some aspects of cognitive impairment in adult mice exposed at postnatal day 7 (P7) to ethanol (EtOH) correlate with slow-wave sleep (SWS) fragmentation (Wilson et al., 2016). We and others have also previously demonstrated that co-treatment with LiCl on the day of EtOH exposure prevents many of the anatomical and physiological impairments observed in adults. Here we explored cognitive function, diurnal rhythms (activity, temperature), SWS, and parvalbumin (PV) and perineuronal net (PNN)-positive cell densities in adult mice that had received a single day of EtOH exposure on P7 and saline-treated littermate controls. Half of the animals also received a LiCl injection on P7. The results suggest that developmental EtOH resulted in adult behavioral hyperactivity, cognitive impairment, and reduced SWS compared to saline controls. Both of these effects were reduced by LiCl treatment on the day of EtOH exposure. Finally, developmental EtOH resulted in decreased PV/PNN-expressing cells in retrosplenial (RS) cortex and dorsal CA3 hippocampus at P90. As with sleep and behavioral activity, LiCl treatment reduced this decrease in PV expression. Together, these results further clarify the long-lasting effects of developmental EtOH on adult behavior, physiology, and anatomy. Furthermore, they demonstrate the neuroprotective effects of LiCl co-treatment on this wide range of developmental EtOH's long-lasting consequences.

Normalization is a common cortical computation widely observed in sensory perception, but its importance in perception of reward value and decision making remains largely unknown. We examined (1) whether normalized value signals occur in the orbitofrontal cortex (OFC) and (2) whether changes in behavioral task context influence the normalized representation of value. We record medial OFC (mOFC) single neuron activity in awake-behaving monkeys during a reward-guided lottery task. mOFC neurons signal the relative values of options via a divisive normalization function when animals freely choose between alternatives. The normalization model, however, performed poorly in a variant of the task where only one of the two possible choice options yields a reward and the other was certain not to yield a reward (so called: "forced choice"). The existence of such context-specific value normalization may suggest that the mOFC contributes valuation signals critical for economic decision making when meaningful alternative options are available.

The neural cell adhesion molecule (NCAM) is expressed both presynaptically and postsynaptically during neuromuscular junction formation. Genetic deletion in mice of all three isoforms (180, 140, and 120 kDa), or just the 180 isoform, suggested that different isoforms played distinct roles in synaptic maturation. Here we characterized in mice of either sex the earliest adhesive contacts between the growth cones of motoneurons and myotubes and their subsequent maturation into functional synapses in cocultures of motoneurons and myotubes, which expressed their normal complement of NCAM isoforms, or were lacking all isoforms either presynaptically or postsynaptically. Growth cone contact with +/+ mouse myotubes resulted in immediate adhesive contacts and the rapid downregulation of growth cone motility. When contacting NCAM-/- myotubes, growth cones touched and retracted/collapsed multiple times and failed to form stable contacts, even after 10 h. Exogenous expression in myotubes of either the 180 or 140 isoform, but not the 120 kDa isoform, rescued the rapid formation of stable contacts, the accumulation of presynaptic and postsynaptic molecules, and functional transmission. When NCAM was absent only in motoneurons, growth cones did not retract upon myotube contact, but, since their motility was not downregulated, they grew off the ends of the myotubes, failing to form synapses. The agrin receptor Lrp4 was strongly downregulated in NCAM-negative myotubes, and motoneuron growth cones did not make stable contacts with Lrp4-negative myotubes. These studies have identified novel roles for presynaptic and postsynaptic NCAM in mediating early cell-cell interactions required for synapse formation.SIGNIFICANCE STATEMENT Although many molecular signals needed to form the functionally effective neuromuscular synapses required for normal movement have been described, the earliest signals that let motoneuron growth cones make stable adhesive contacts with myotubes and cease motility are not well understood. Using dynamic imaging of motoneuron-myotube cocultures, we show that NCAM is required on both the growth cone and myotube and that different NCAM isoforms mediate initial adhesion and the downregulation of growth cone motility. The agrin receptor Lrp4 was also essential for initial adhesive contacts and was downregulated on NCAM-/- myotubes. Our identification of novel roles for NCAM and Lrp4 and possible interactions between them in transforming motile growth cones into stable contacts opens interesting new avenues for exploration.

During forebrain development, a telencephalic organizer called the cortical hem is crucial for inducing hippocampal fate in adjacent cortical neuroepithelium. How the hem is restricted to its medial position is therefore a fundamental patterning issue. Here, we demonstrate that Foxg1-Lhx2 interactions are crucial for the formation of the hem. Loss of either gene causes a region of the cortical neuroepithelium to transform into hem. We show that FOXG1 regulates Lhx2 expression in the cortical primordium. In the absence of Foxg1, the presence of Lhx2 is sufficient to suppress hem fate, and hippocampal markers appear selectively in Lhx2-expressing regions. FOXG1 also restricts the temporal window in which loss of Lhx2 results in a transformation of cortical primordium into hem. Therefore, Foxg1 and Lhx2 form a genetic hierarchy in the spatiotemporal regulation of cortical hem specification and positioning, and together ensure the normal development of this hippocampal organizer.

Because salicylism is a clinical diagnosis, the serum concentration should be interpreted in conjunction with the clinical presentation. A 26-year-old man presented to the Emergency Department with abdominal painand had extremely elevated serum triglycerides (>7000 mg/dL). Ethanol, acetaminophen, and salicylate concentrations were checked because of concern of self-injurious behavior, which returned at 13.1 mg/dL, undetectable, and >100 mg/dL, respectively. His basic metabolic panel revealed a bicarbonate of 23 mEq/L and an anion gap of 11. An arterial blood gas showed a pH 7.39 and a PCO2 of 36.6 mmHg. On physical examination, he was awake and alert, and had a respiratory rate of 12–14/min. The possible effect of hyperlipidemia to falsely elevate the salicylate concentration was recognized. He was treated for severe hypertriglyceridemia and as his triglyceride level dropped, his repeat salicylate concentration was <1 mg/dL. Since dfferent sized lipoproteins contribute variably to serum sample turbiditythey have the potential to interfere with the absorption of light thereby producing erroneous laboratory results . Clinicians need to be aware of the implications of severe hyperlipidemia and interference to prevent clinical errors based on false positive laboratory results