Voltage-gated potassium channels control extended access cocaine seeking: a role for nucleus accumbens astrocytes

Dopaminergic signaling in the nucleus accumbens shell (NAc) regulates neuronal activity relevant to reward-related learning, including cocaine-associated behaviors. Although astrocytes respond to dopamine and cocaine with structural changes, the impact of dopamine and cocaine on astrocyte functional plasticity has not been widely studied. Specifically, behavioral implications of voltage-gated channel activity in the canonically non-excitable astrocytes are not known. We characterized potassium channel function in NAc astrocytes following exposure to exogenous dopamine or cocaine self-administration training under short (2 h/day) and extended (6 h/day) access schedules. Electrophysiological, Ca2+ imaging, mRNA, and mass spectrometry tools were used for molecular characterization. Behavioral effects were examined after NAc-targeted microinjections of channel antagonists and astroglial toxins. Exogenous dopamine increased activity of currents mediated by voltage-gated (Kv7) channels in NAc astrocytes. This was associated with a ~5-fold increase in expression of Kcnq2 transcript level in homogenized NAc micropunches. Matrix-assisted laser desorption/ionization mass spectrometry revealed increased NAc dopamine levels in extended access, relative to short access, rats. Kv7 inhibition selectively increased frequency and amplitude of astrocyte intracellular Ca2+ transients in NAc of extended access rats. Inhibition of Kv7 channels in the NAc attenuated cocaine-seeking in extended access rats only, an effect that was occluded by microinjection of the astrocyte metabolic poison, fluorocitrate. These results suggest that voltage-gated K+ channel signaling in NAc astrocytes is behaviorally relevant, support Kv7-mediated regulation of astrocyte Ca2+ signals, and propose novel mechanisms of neuroglial interactions relevant to drug use.

Targeting the Microbiome to Improve Gut Health and Breathing Function After Spinal Cord Injury

Spinal cord injury (SCI) is a devastating condition characterized by impaired motor and sensory function, as well as internal organ pathology and dysfunction. This internal organ dysfunction, particularly gastrointestinal (GI) complications, and neurogenic bowel, can reduce the quality of life of individuals with an SCI and potentially hinder their recovery. The gut microbiome impacts various central nervous system functions and has been linked to a number of health and disease states. An imbalance of the gut microbiome, i.e., gut dysbiosis, contributes to neurological disease and may influence recovery and repair processes after SCI. Here we examine the impact of high cervical SCI on the gut microbiome and find that transient gut dysbiosis with persistent gut pathology develops after SCI. Importantly, probiotic treatment improves gut health and respiratory motor function measured through whole-body plethysmography. Concurrent with these improvements was a systemic decrease in the cytokine tumor necrosis factor-alpha and an increase in neurite sprouting and regenerative potential of neurons. Collectively, these data reveal the gut microbiome as an important therapeutic target to improve visceral organ health and respiratory motor recovery after SCI.

Research Highlights

Cervical spinal cord injury (SCI) causes transient gut dysbiosis and persistent gastrointestinal (GI) pathology.Treatment with probiotics after SCI leads to a healthier GI tract and improved respiratory motor recovery.Probiotic treatment decreases systemic tumor necrosis factor-alpha and increases the potential for sprouting and regeneration of neurons after SCI.The gut microbiome is a valid target to improve motor function and secondary visceral health after SCI.

Loss of carnitine palmitoyltransferase 1a reduces docosahexaenoic acid-containing phospholipids and drives sexually dimorphic liver disease in mice

BACKGROUND AND AIMS

Genome and epigenome wide association studies identified variants in carnitine palmitoyltransferase 1a (CPT1a) that associate with lipid traits. The goal of this study was to determine the role of liver-specific CPT1a on hepatic lipid metabolism.

APPROACH AND RESULTS

Male and female liver-specific knockout (LKO) and littermate controls were placed on a low-fat or high-fat diet (60% kcal fat) for 15 weeks. Mice were necropsied after a 16 h fast, and tissues were collected for lipidomics, matrix-assisted laser desorption ionization mass spectrometry imaging, kinome analysis, RNA-sequencing, and protein expression by immunoblotting. Female LKO mice had increased serum alanine aminotransferase levels which were associated with greater deposition of hepatic lipids, while male mice were not affected by CPT1a deletion relative to male control mice. Mice with CPT1a deletion had reductions in DHA-containing phospholipids at the expense of monounsaturated fatty acids (MUFA)-containing phospholipids in whole liver and at the level of the lipid droplet (LD). Male and female LKO mice increased RNA levels of genes involved in LD lipolysis (Plin2, Cidec, G0S2) and in polyunsaturated fatty acid metabolism (Elovl5, Fads1, Elovl2), while only female LKO mice increased genes involved in inflammation (Ly6d, Mmp12, Cxcl2). Kinase profiling showed decreased protein kinase A activity, which coincided with increased PLIN2, PLIN5, and G0S2 protein levels and decreased triglyceride hydrolysis in LKO mice.

CONCLUSIONS

Liver-specific deletion of CPT1a promotes sexually dimorphic steatotic liver disease (SLD) in mice, and here we have identified new mechanisms by which females are protected from HFD-induced liver injury.

RIT1 regulation of CNS lipids RIT1 deficiency Alters cerebral lipid metabolism and reduces white matter tract oligodendrocytes and conduction velocities

Oligodendrocytes (OLs) generate lipid-rich myelin membranes that wrap axons to enable efficient transmission of electrical impulses. Using a RIT1 knockout mouse model and in situ high-resolution matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) coupled with MS-based lipidomic analysis to determine the contribution of RIT1 to lipid homeostasis. Here, we report that RIT1 loss is associated with altered lipid levels in the central nervous system (CNS), including myelin-associated lipids within the corpus callosum (CC). Perturbed lipid metabolism was correlated with reduced numbers of OLs, but increased numbers of GFAP+ glia, in the CC, but not in grey matter. This was accompanied by reduced myelin protein expression and axonal conduction deficits. Behavioral analyses revealed significant changes in voluntary locomotor activity and anxiety-like behavior in RIT1KO mice. Together, these data reveal an unexpected role for RIT1 in the regulation of cerebral lipid metabolism, which coincide with altered white matter tract oligodendrocyte levels, reduced axonal conduction velocity, and behavioral abnormalities in the CNS.

Gys1 Antisense Therapy Prevents Disease-Driving Aggregates and Epileptiform Discharges in a Lafora Disease Mouse Model

Patients with Lafora disease have a mutation in EPM2A or EPM2B, resulting in dysregulation of glycogen metabolism throughout the body and aberrant glycogen molecules that aggregate into Lafora bodies. Lafora bodies are particularly damaging in the brain, where the aggregation drives seizures with increasing severity and frequency, coupled with neurodegeneration. Previous work employed mouse genetic models to reduce glycogen synthesis by approximately 50%, and this strategy significantly reduced Lafora body formation and disease phenotypes. Therefore, an antisense oligonucleotide (ASO) was developed to reduce glycogen synthesis in the brain by targeting glycogen synthase 1 (Gys1). To test the distribution and efficacy of this drug, the Gys1-ASO was administered to Epm2b-/- mice via intracerebroventricular administration at 4, 7, and 10 months. The mice were then sacrificed at 13 months and their brains analyzed for Gys1 expression, glycogen aggregation, and neuronal excitability. The mice treated with Gys1-ASO exhibited decreased Gys1 protein levels, decreased glycogen aggregation, and reduced epileptiform discharges compared to untreated Epm2b-/- mice. This work provides proof of concept that a Gys1-ASO halts disease progression of EPM2B mutations of Lafora disease.

Loss of Carnitine Palmitoyltransferase 1a Reduces Docosahexaenoic Acid-Containing Phospholipids and Drives Sexually Dimorphic Liver Disease in Mice

Background and Aims

Genome and epigenome wide association studies identified variants in carnitine palmitoyltransferase 1a (CPT1a) that associate with lipid traits. The goal of this study was to determine the impact by which liver-specific CPT1a deletion impacts hepatic lipid metabolism.

Approach and Results

Six-to-eight-week old male and female liver-specific knockout (LKO) and littermate controls were placed on a low-fat or high-fat diet (HFD; 60% kcal fat) for 15 weeks. Mice were necropsied after a 16 hour fast, and tissues were collected for lipidomics, matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI), kinome analysis, RNA-sequencing, and protein expression by immunoblotting. Female LKO mice had increased serum alanine aminotransferase (ALT) levels which were associated with greater deposition of hepatic lipids, while male mice were not affected by CPT1a deletion relative to male control mice. Mice with CPT1a deletion had reductions in DHA-containing phospholipids at the expense of monounsaturated fatty acids (MUFA)-containing phospholipids in both whole liver and at the level of the lipid droplet (LD). Male and female LKO mice increased RNA levels of genes involved in LD lipolysis ( Plin2 , Cidec , G0S2 ) and in polyunsaturated fatty acid (PUFA) metabolism ( Elovl5, Fads1, Elovl2 ), while only female LKO mice increased genes involved in inflammation ( Ly6d, Mmp12, Cxcl2 ). Kinase profiling showed decreased protein kinase A (PKA) activity, which coincided with increased PLIN2, PLIN5, and G0S2 protein levels and decreased triglyceride hydrolysis in LKO mice.

Conclusions

Liver-specific deletion of CPT1a promotes sexually dimorphic steatotic liver disease (SLD) in mice, and here we have identified new mechanisms by which females are protected from HFD-induced liver injury.

Graphical Summary

Spatial Metabolome Lipidome and Glycome from a Single brain Section

Metabolites, lipids, and glycans are fundamental biomolecules involved in complex biological systems. They are metabolically channeled through a myriad of pathways and molecular processes that define the physiology and pathology of an organism. Here, we present a blueprint for the simultaneous analysis of spatial metabolome, lipidome, and glycome from a single tissue section using mass spectrometry imaging. Complimenting an original experimental protocol, our workflow includes a computational framework called Spatial Augmented Multiomics Interface (Sami) that offers multiomics integration, high dimensionality clustering, spatial anatomical mapping with matched multiomics features, and metabolic pathway enrichment to providing unprecedented insights into the spatial distribution and interaction of these biomolecules in mammalian tissue biology.

Spatial metabolomics reveals glycogen as an actionable target for pulmonary fibrosis

Matrix assisted laser desorption/ionization imaging has greatly improved our understanding of spatial biology, however a robust bioinformatic pipeline for data analysis is lacking. Here, we demonstrate the application of high-dimensionality reduction/spatial clustering and histopathological annotation of matrix assisted laser desorption/ionization imaging datasets to assess tissue metabolic heterogeneity in human lung diseases. Using metabolic features identified from this pipeline, we hypothesize that metabolic channeling between glycogen and N-linked glycans is a critical metabolic process favoring pulmonary fibrosis progression. To test our hypothesis, we induced pulmonary fibrosis in two different mouse models with lysosomal glycogen utilization deficiency. Both mouse models displayed blunted N-linked glycan levels and nearly 90% reduction in endpoint fibrosis when compared to WT animals. Collectively, we provide conclusive evidence that lysosomal utilization of glycogen is required for pulmonary fibrosis progression. In summary, our study provides a roadmap to leverage spatial metabolomics to understand foundational biology in pulmonary diseases.

Cervical spinal cord injury leads to injury and altered metabolism in the lungs

High-cervical spinal cord injury often disrupts respiratory motor pathways and disables breathing in the affected population. Moreover, cervically injured individuals are at risk for developing acute lung injury, which predicts substantial mortality rates. While the correlation between acute lung injury and spinal cord injury has been found in the clinical setting, the field lacks an animal model to interrogate the fundamental biology of this relationship. To begin to address this gap in knowledge, we performed an experimental cervical spinal cord injury (N = 18) alongside sham injury (N = 3) and naïve animals (N = 15) to assess lung injury in adult rats. We demonstrate that animals display some early signs of lung injury two weeks post-spinal cord injury. While no obvious histological signs of injury were observed, the spinal cord injured cohort displayed significant signs of metabolic dysregulation in multiple pathways that include amino acid metabolism, lipid metabolism, and N-linked glycosylation. Collectively, we establish for the first time a model of lung injury after spinal cord injury at an acute time point that can be used to monitor the progression of lung damage, as well as identify potential targets to ameliorate acute lung injury.

APOE modulates microglial immunometabolism in response to age, amyloid pathology, and inflammatory challenge

The E4 allele of Apolipoprotein E (APOE) is associated with both metabolic dysfunction and a heightened pro-inflammatory response: two findings that may be intrinsically linked through the concept of immunometabolism. Here, we combined bulk, single-cell, and spatial transcriptomics with cell-specific and spatially resolved metabolic analyses in mice expressing human APOE to systematically address the role of APOE across age, neuroinflammation, and AD pathology. RNA sequencing (RNA-seq) highlighted immunometabolic changes across the APOE4 glial transcriptome, specifically in subsets of metabolically distinct microglia enriched in the E4 brain during aging or following an inflammatory challenge. E4 microglia display increased Hif1α expression and a disrupted tricarboxylic acid (TCA) cycle and are inherently pro-glycolytic, while spatial transcriptomics and mass spectrometry imaging highlight an E4-specific response to amyloid that is characterized by widespread alterations in lipid metabolism. Taken together, our findings emphasize a central role for APOE in regulating microglial immunometabolism and provide valuable, interactive resources for discovery and validation research.

In situ mass spectrometry imaging reveals heterogeneous glycogen stores in human normal and cancerous tissues

Glycogen dysregulation is a hallmark of aging, and aberrant glycogen drives metabolic reprogramming and pathogenesis in multiple diseases. However, glycogen heterogeneity in healthy and diseased tissues remains largely unknown. Herein, we describe a method to define spatial glycogen architecture in mouse and human tissues using matrix-assisted laser desorption/ionization mass spectrometry imaging. This assay provides robust and sensitive spatial glycogen quantification and architecture characterization in the brain, liver, kidney, testis, lung, bladder, and even the bone. Armed with this tool, we interrogated glycogen spatial distribution and architecture in different types of human cancers. We demonstrate that glycogen stores and architecture are heterogeneous among diseases. Additionally, we observe unique hyperphosphorylated glycogen accumulation in Ewing sarcoma, a pediatric bone cancer. Using preclinical models, we correct glycogen hyperphosphorylation in Ewing sarcoma through genetic and pharmacological interventions that ablate in vivo tumor growth, demonstrating the clinical therapeutic potential of targeting glycogen in Ewing sarcoma.

In situ spatial glycomic imaging of mouse and human Alzheimer's disease brains

N-linked protein glycosylation in the brain is an understudied facet of glucose utilization that impacts a myriad of cellular processes including resting membrane potential, axon firing, and synaptic vesicle trafficking. Currently, a spatial map of N-linked glycans within the normal and Alzheimer's disease (AD) human brain does not exist. A comprehensive analysis of the spatial N-linked glycome would improve our understanding of brain energy metabolism, linking metabolism to signaling events perturbed during AD progression, and could illuminate new therapeutic strategies. Herein we report an optimized in situ workflow for enzyme-assisted, matrix-assisted laser desorption and ionization (MALDI) mass spectrometry imaging (MSI) of brain N-linked glycans. Using this workflow, we spatially interrogated N-linked glycan heterogeneity in both mouse and human AD brains and their respective age-matched controls. We identified robust regional-specific N-linked glycan changes associated with AD in mice and humans. These data suggest that N-linked glycan dysregulation could be an underpinning of AD pathologies.

Measurement properties of the WHO Disability Assessment Schedule 2.0 for evaluating functional status after inpatient surgery

BACKGROUND

Expert recommendations propose the WHO Disability Assessment Schedule (WHODAS) 2.0 as a core outcome measure in surgical studies, yet data on its long-term measurement properties remain limited. These were evaluated in a secondary analysis of the Measurement of Exercise Tolerance before Surgery (METS) prospective cohort.

METHODS

Participants were adults (40 years of age or older) who underwent inpatient non-cardiac surgery. The 12-item WHODAS and EQ-5DTM-3L questionnaires were administered preoperatively (in person) and 1 year postoperatively (by telephone). Responsiveness was characterized using standardized response means (SRMs) and correlation coefficients between change scores. Construct validity was evaluated using correlation coefficients between 1-year scores and comparisons of WHODAS scores across clinically relevant subgroups.

RESULTS

The analysis included 546 patients. There was moderate correlation between changes in WHODAS and various EQ-5DTM subscales. The strongest correlation was between changes in WHODAS and changes in the functional domains of the EQ-5D-3L-for example, mobility (Spearman's rho 0.40, 95 per cent confidence interval [c.i.] 0.32 to 0.48) and usual activities (rho 0.45, 95 per cent c.i. 0.30 to 0.52). When compared across quartiles of EQ-5D index change, median WHODAS scores followed expected patterns of change. In subgroups with expected functional status changes, the WHODAS SRMs ranged from 'small' to 'large' in the expected directions of change. At 1 year, the WHODAS demonstrated convergence with the EQ-5D-3L functional domains, and good discrimination between patients with expected differences in functional status.

CONCLUSION

The WHODAS questionnaire has construct validity and responsiveness as a measure of functional status at 1 year after major surgery.

High-dimensionality reduction clustering of complex carbohydrates to study lung cancer metabolic heterogeneity

The tumor microenvironment contains a heterogeneous population of stromal and cancer cells that engage in metabolic crosstalk to ultimately promote tumor growth and contribute to progression. Due to heterogeneity within solid tumors, pooled mass spectrometry workflows are less sensitive at delineating unique metabolic perturbations between stromal and immune cell populations. Two critical, but understudied, facets of glucose metabolism are anabolic pathways for glycogen and N-linked glycan biosynthesis. Together, these complex carbohydrates modulate bioenergetics and protein-structure function, and create functional microanatomy in distinct cell populations within the tumor heterogeneity. Herein, we combine high-dimensionality reduction and clustering (HDRC) analysis with matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) and demonstrate its ability for the comprehensive assessment of tissue histopathology and metabolic heterogeneity in human FFPE sections. In human lung adenocarcinoma (LUAD) tumor tissues, HDRC accurately clusters distinct regions and cell populations within the tumor microenvironment, including tumor cells, tumor-infiltrating lymphocytes, cancer-associated fibroblasts, and necrotic regions. In-depth pathway enrichment analyses revealed unique metabolic pathways are associated with each distinct pathological region. Further, we highlight the potential of HDRC analysis to study complex carbohydrate metabolism in a case study of lung cancer disparity. Collectively, our results demonstrate the promising potentials of HDRC of pixel-based carbohydrate analysis to study cell-type and regional-specific stromal signaling within the tumor microenvironment.

Abstract 2819: Mass spectrometry imaging reveals heterogeneous glycogen metabolism in non small cell lung cancer

Lung cancer is the leading cause of cancer related death worldwide, with a high mortality rate even when diagnosed at an early stage. Identifying the unique molecular features that drive disease progression within distinct tumor subtypes is a critical step in lung cancer research that could advance our understanding of lung cancer biology, leading to predictive biomarkers and novel therapies. Glycogen is the primary source of carbohydrate storage in most issues, and its degradation products are intimately connection to central carbon metabolism. Recently, aberrant glycogen accumulation has been observed in lung tumors and been reported to promote lung cancer progression. Despite these findings, the full clinical implications of dysregulated glycogen metabolism and its role in lung cancer tumorigenesis remain largely unknown. Due to its unique physiochemical properties, glycogen is extremely difficult to measure biochemically and visualize in situ. Herein, we describe a novel method to image microenvironmental glycogen via enzymatic release of glycogen substrates coupled to matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI). Our assay provides robust information on glycogen structure and phosphate composition with spatial distribution. With this technique, we analyzed glycogen chain length and glycogen phosphate content from tissue microarrays containing over 200 lung cancer patient samples banked at the University of Kentucky with over 10 years of clinical metadata. Using MALDI-MSI, we found significant glycogen accumulation in lung tumor tissue compared to match normal lung across all patients, and found adenocarcinoma (LUAD) samples contained higher glycogen content than squamous cell carcinoma (SCC). Regional analysis by MALDI-MSI revealed SCC primarily accumulates glycogen in the stroma and blood vessels, but not in tumors. Notably, LUAD patient tumors exhibit decreased expression of laforin, a glucan phosphatase that plays a key role in glycogen phosphorylation and glycogen degradation. Low laforin expression also corresponds to poorer overall survival in LUAD patients. In vivo, deletion of Epm2a (the gene that encodes laforin) in KRASG12D/p53-/- mice results in increased tumor burden and accumulation of hyperphosphorylated intratumoral glycogen. Further, A549 LUAD xenografts treated with guaiacol, a glycogen synthase inhibitor, show markedly reduced tumor growth, while guaiacol had no effect on H2030 SCC tumor growth. Given the significant effect of glycogen accumulation on in vivo tumor growth, our data suggest the glycogen metabolic pathway represents a novel therapeutic target specifically for LUAD patients. Together, our study describes a novel method to visualize glycogen structure using MALDI-MSI and reveals unique metabolic features that contribute to LUAD disease progression.

Citation Format: Lindsey R. Conroy, Lyndsay EA Young, Harrison A. Clarke, Alexandra E. Stanback, Michael D. Buoncristiani, Christine F. Brainson, Derek B. Allison, Ramon C. Sun, Richard R. Drake. Mass spectrometry imaging reveals heterogeneous glycogen metabolism in non small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2819.

In Situ Analysis of N-Linked Glycans as Potential Biomarkers of Clinical Course in Human Prostate Cancer

Prostate cancer is the most common cancer in men worldwide. Despite its prevalence, there is a critical knowledge gap in understanding factors driving disparities in survival among different cohorts of patients with prostate cancer. Identifying molecular features separating disparate populations is an important first step in prostate cancer research that could lead to fundamental hypotheses in prostate biology, predictive biomarker discovery, and personalized therapy. N-linked glycosylation is a cotranslational event during protein folding that modulates a myriad of cellular processes. Recently, aberrant N-linked glycosylation has been reported in prostate cancers. However, the full clinical implications of dysregulated glycosylation in prostate cancer has yet to be explored. Herein, we performed direct on-tissue analysis of N-linked glycans using matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) from tissue microarrays of over 100 patient tumors with over 10 years of follow-up metadata. We successfully identified a panel of N-glycans that are unique between benign and prostate tumor tissue. Specifically, high-mannose as well as tri-and tetra-antennary N-glycans were more abundant in tumor tissue and increase proportionally with tumor grade. Further, we expanded our analyses to examine the N-glycan profiles of Black and Appalachian patients and have identified unique glycan signatures that correlate with recurrence in each population. Our study highlights the potential applications of MALDI-MSI for digital pathology and biomarker discovery for prostate cancer. IMPLICATIONS: MALDI-MSI identifies N-glycan perturbations in prostate tumors compared with benign tissue. This method can be utilized to predict prostate cancer recurrence and study prostate cancer disparities.

Regional N-glycan and lipid analysis from tissues using MALDI-mass spectrometry imaging

N-glycans and lipids are structural metabolites that play important roles in cellular processes. Both show unique regional distribution in tissues; therefore, spatial analyses of these metabolites are crucial to our understanding of cellular physiology. Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) is an innovative technique that enables in situ detection of analytes with spatial distribution. This workflow details a MALDI-MSI protocol for the spatial profiling of N-glycans and lipids from tissues following application of enzyme and MALDI matrix.

For complete details on the use and execution of this protocol, please refer to Drake et al. (2018) and Andres et al. (2020).

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MALDI-MSI of N-glycans and lipids from tissues

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Enzyme-assisted release of N-linked glycans from formalin-fixed tissues

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High-velocity deposition of matrix to improve rigor and reproducibility

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Ion mobility separation of analytes from matrix as part of imaging workflow

Combined hippocampal and amygdala lesions block learning of a response-independent form of occasion setting

This study compared rats with dorsal striatal, ventrolateral prefrontal cortical, and combined lesions of the hippocampus and amygdala to sham controls on a conditional discrimination task in which contextual cues modulated a taste aversion. All groups were able to acquire this occasion setting task. The 2nd experiment functionally minimized the stimulus-response component of the paradigm, creating a "tasteless" form of occasion setting. Rats with pretraining lesions of the hippocampus and amygdala were impaired compared with shams on the acquisition of this tasteless occasion setting task. Rats with posttraining combined lesions did not retain the ability to perform the tasteless occasion setting task learned preoperatively. Rats with selective lesions of either the hippocampus or the amygdala alone were not impaired in the acquisition of the tasteless occasion setting task. The findings suggest that this occasion setting task may be learned by several redundant neural systems.

Identification of lamina V and VII interneurons presynaptic to adrenal sympathetic preganglionic neurons in rats using a recombinant herpes simplex virus type 1

Although indirect evidence suggests that the control of sympathetic preganglionic neurons is mediated to a great extent through interneurons, little is known about the location, morphology or neurotransmitter phenotype of such interneurons. This limitation seriously impedes our understanding of spinal synaptic circuits crucial to control of arterial pressure and other visceral functions. We used a highly neurotropic, minimally cytopathic recombinant herpes simplex virus type-1 to study spinal "sympathetic" interneurons labelled by trans-synaptic transport of the virus from the adrenal gland in rats. Approximately 120-320 infected neurons/rat were identified by immunocytochemical detection of the viral antigen. We distinguished between virus-infected preganglionic neurons and infected interneurons by (i) their location within the spinal laminae, (ii) their size and shape and (iii) the presence or absence of immunoreactivity for the acetylcholine-synthesizing enzyme, choline acetyltransferase, a marker of sympathetic preganglionic neurons. Virus-labelled sympathetic preganglionic neurons were found within the known spinal preganglionic nuclei. Non-cholinergic, virus-labelled neurons were located throughout lamina VII and in the ventral portion of lamina V. These putative interneurons were found in the major spinal preganglionic nuclei, usually intermingled with the preganglionic neurons. Sometimes, they were located in clusters separate from the preganglionic neurons. The interneurons were approximately 15 microm in diameter, smaller than the average preganglionic neuron (diameter=25 microm), and had a few fine processes emanating from them. These non-cholinergic interneurons constituted approximately one-half of the population of virus-infected neurons. In summary, with the use of a recombinant herpes simplex virus, we identified a large number of non-cholinergic interneurons close to, or intermingled with, adrenal sympathetic preganglionic neurons. The neurotransmitter phenotype of these neurons remains to be determined but they likely integrate much of the supraspinal and primary afferent inputs to spinal preganglionic neurons that control arterial pressure and other visceral functions.

Uterine leiomyosarcoma with intracerebral metastasis: a case report

A case of a 36-year-old woman with a past history of uterine leiomyosarcoma and an intracerebral metastasis is reported. The patient presented with a 24-hour history of severe headache with coma, and the CT findings were consistent with a metastatic lesion. Pathological examination of the operative specimen showed features of a leiomyosarcoma. Uterine leiomyosarcoma is an uncommon tumor and metastasis to the brain is rare.

Identification of a putative cellular receptor for the lentivirus visna virus

One mechanism by which viral tropism may be controlled is by the expression of a specific virus receptor on the cell surface. This paper reports the identification of a putative cellular receptor for visna virus, the prototype virus of the family Lentiviridae. Using a virus overlay protein blot assay we identified a group of polypeptides of apparent Mr 30K to 33K which interacts with visna virus and is present on permissive but not non-permissive cells. A rat polyclonal anti-ovine major histocompatibility complex (MHC) class II antigen (Ag) serum raised to immunopurified MHC class II Ag, but not preimmune serum, blocked the interaction of visna virus with these polypeptides. In an ELISA, immunopurified MHC class II Ag bound to visna virus but not to bovine parainfluenza 3 virus. Preincubation of visna virus with immunopurified soluble MHC class II Ag resulted in a marked decrease in virus-induced syncytium formation, i.e. preincubation with class II Ag inhibited infection with visna virus, but we have been unable to inhibit infection using class II Ag-specific antisera. These results suggest that ovine MHC class II Ag acts as a component of a cellular receptor for visna virus. This is of particular interest owing to the close similarities between visna virus and human immunodeficiency virus (HIV), and the relationship between MHC class II and CD4, the cellular receptor for HIV. It is also of relevance to recent reports that a growing number of viruses utilize polypeptides of the Ig supergene family as receptors.

Complex partial seizures associated with a temporomandibular joint defect

A case of a 32-year-old man is reported with complex partial seizures secondary to a right inferior temporal epileptic focus immediately overlying an abnormality of the temporomandibular joint, with a defect in the middle temporal fossa that allowed the mandibular condyle to contuse the temporal lobe.

Prenatal diagnosis of cystic fibrosis by microvillar enzyme assay on a sequence of 258 pregnancies

Prenatal diagnosis of cystic fibrosis by microvillar enzyme assay on amniotic fluid supernatant has been carried out on 258 sequential pregnancies with a 1 in 4 recurrence risk, all with known outcome. In general the three enzymes evaluated, gamma-glutamyltranspeptidase, aminopeptidase M and the intestinal isoenzyme of alkaline phosphatase, showed a high degree of concordance. However, there were two unusual patterns of microvillar enzyme activity; in seven cases a low gamma-glutamyltranspeptidase activity was associated with elevated values of intestinal alkaline phosphatase, and in ten cases there were isolated low values of intestinal alkaline phosphatase. The former pattern was found to be associated with cystic fibrosis in five cases, while the latter was associated with a normal outcome in all ten cases. A retrospective analysis of enzyme values suggested that the optimal system for minimizing false positives and false negatives was to define foetal cystic fibrosis as a sample where two of the three microvillar enzymes were below a cut-off of half the median value for the gestational week. If such scoring were applied to the cases where conventional microvillar enzyme patterns were observed, the false positive rate was 2.3% and the false negative rate 4.4% between 17 and 20 weeks of gestation.

An abnormal pattern of amniotic fluid microvillar enzymes signalling fetal cystic fibrosis

We have observed seven pregnancies at risk for fetal cystic fibrosis where second-trimester amniotic fluid microvillar enzyme activities presented an unusual pattern. Low gamma-glutamyltranspeptidase and borderline alpha-glucosidase values were associated with normal aminopeptidase M and intestinal alkaline phosphatase values. All seven pregnancies went to term; five of the seven infants were affected with cystic fibrosis.

Sitting prone position for the posterior surgical approach to the spine and posterior fossa

The sitting prone position is compared with the standard laminectomy prone position and the sitting up position for posterior fossa surgery. We measured central venous pressure and airway pressure with the patient in different positions to determine the comparative efficacy of the sitting prone position. On a linear average, the central venous pressure increased by 6.83 cm H2O and the airway pressure increased by 3.16 cm H2O when the patient was changed from the supine to the standard prone position under general anesthesia; with a change from the standard prone position to the sitting prone position, the central venous pressure decreased by 10.45 cm H2O and the airway pressure decreased by 3.66 cm H2O. However, comparing the sitting prone position for posterior fossa surgery with the sitting up position, there was no statistically significant difference in central venous or airway pressure.