Subclonal Cancer Driver Mutations Are Prevalent in the Unresected Peritumoral Edema of Adult Diffuse Gliomas

Adult diffuse gliomas commonly recur regardless of therapy. As recurrence typically arises from the peritumoral edema adjacent to the resected bulk tumor, the profiling of somatic mutations from infiltrative malignant cells within this critical, unresected region could provide important insights into residual disease. A key obstacle has been the inability to distinguish between next-generation sequencing (NGS) noise and the true but weak signal from tumor cells hidden among the noncancerous brain tissue of the peritumoral edema. Here, we developed and validated True2 sequencing to reduce NGS-associated errors to <1 false positive/100 kb panel positions while detecting 97.6% of somatic mutations with an allele frequency ≥0.1%. True2 was then used to study the tumor and peritumoral edema of 22 adult diffuse gliomas including glioblastoma, astrocytoma, oligodendroglioma, and NF1-related low-grade neuroglioma. The tumor and peritumoral edema displayed a similar mutation burden, indicating that surgery debulks these cancers physically but not molecularly. Moreover, variants in the peritumoral edema included unique cancer driver mutations absent in the bulk tumor. Finally, analysis of multiple samples from each patient revealed multiple subclones with unique mutations in the same gene in 17 of 22 patients, supporting the occurrence of convergent evolution in response to patient-specific selective pressures in the tumor microenvironment that may form the molecular foundation of recurrent disease. Collectively, True2 enables the detection of ultralow frequency mutations during molecular analyses of adult diffuse gliomas, which is necessary to understand cancer evolution, recurrence, and individual response to therapy.

SIGNIFICANCE

True2 is a next-generation sequencing workflow that facilitates unbiased discovery of somatic mutations across the full range of variant allele frequencies, which could help identify residual disease vulnerabilities for targeted adjuvant therapies.

Abstract 212: True2 duplex sequencing reveals a diverse landscape of unique somatic mutations beyond the surgical margins of high- and low-grade diffuse gliomas

Introduction: High- and low-grade diffuse gliomas commonly recur regardless of therapy. Here, we sought to detect and profile molecular evidence of disease in nearby brain tissue absent of tumor by standard-of-care clinical imaging.

Methods: Twenty-two patients presenting to the University of Utah with radiographic evidence of a new high- to low-grade intrinsic brain tumor were enrolled after providing written informed consent. Using intraoperative stereotactic guidance, tissue was acquired from bulky tumor (36 samples) and beyond the surgical margins in peritumoral edema (29 samples). All samples underwent somatic mutation discovery using a custom-designed 114 kb panel (115 genes) and True2 duplex sequencing. True2 is a duplex adapter-based technology developed and empirically validated to achieve &gt;95% sensitivity for an allele frequency ≥0.1% at a false positive rate of &lt;1 per 100 kb panel positions.

Results: Somatic mutations were detected in all samples regardless of radiographic location. The mean number of mutations was similar between bulky tumor and peritumoral edema (5.6±2.4 vs. 5.1±2.9 mutations/sample, respectively; P=0.48). Although the mean allele frequency of variants was higher in tumor compared to edema (16.0±21.2% vs. 11.2±17.4%, respectively; P=0.017), there was a strong overlap in the allele frequency ranges (tumor: 0.07% to 90.3% vs. edema: 0.10% to 75.6%). Notably, one-third of all the somatic mutations detected had an allele frequency &lt;0.5%. Common diagnostic mutations specific to each tumor type were present in both tumor and edema - TERT promoter mutations in glioblastoma and oligodendroglioma; IDH1/2 mutations in astrocytoma and oligodendroglioma. In edema, mutations associated with glioblastoma but unique to a single sample occurred in TP53, EGFR, PTEN, NF1, ATRX, SCN9A, and MTOR at an allele frequency ranging from 0.10% to 20.22%. The edema of astrocytomas similarly harbored unique mutations in TP53, PTEN, and NF1, but mutations in EGFR, ATRX, SCN9A, and MTOR were absent. In contrast to both glioblastoma and astrocytoma, oligodendrogliomas exhibited a diverse collection of unique CIC and PAFAH1B3 mutations in edema at an allele frequency between 0.13% and 3.63%.

Conclusions: The application of True2 technology to conduct a discovery search for very-low frequency somatic mutations found the molecular burden between tumor and adjacent edema to be remarkably similar. Our findings indicate an extensive tumor presence beyond the surgical margins in diffuse gliomas with unique and abundant somatic mutations that may form the foundation of recurrent lesions. Molecular analysis of adjacent tissue identified as radiographically unaffected by bulky tumor to better characterize the mutational landscape of migratory subclones may directly impact personalized medicine for high- and low-grade diffuse glioma patients.

Citation Format: Hunter Underhill, Michael Karsy, Christian Davidson, Sabine Hellwig, Samuel Stevenson, Sydney Vincenti, Charlie Dean, Brion Harrison, Eric Goold, Mary Bronner, Howard Colman, Randy Jensen. True2 duplex sequencing reveals a diverse landscape of unique somatic mutations beyond the surgical margins of high- and low-grade diffuse gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 212.

Negative refraction in hyperbolic hetero-bicrystals

We visualized negative refraction of phonon polaritons, which occurs at the interface between two natural crystals. The polaritons-hybrids of infrared photons and lattice vibrations-form collimated rays that display negative refraction when passing through a planar interface between the two hyperbolic van der Waals materials: molybdenum oxide (MoO₃) and isotopically pure hexagonal boron nitride (h¹¹BN). At a special frequency ω₀, these rays can circulate along closed diamond-shaped trajectories. We have shown that polariton eigenmodes display regions of both positive and negative dispersion interrupted by multiple gaps that result from polaritonic-level repulsion and strong coupling.

Shear Stress-Responsive Polymersome Nanoreactors Inspired by the Marine Bioluminescence of Dinoflagellates

Some marine plankton called dinoflagellates emit light in response to the movement of surrounding water, resulting in a phenomenon called milky seas or sea sparkle. The underlying concept, a shear-stress induced permeabilisation of biocatalytic reaction compartments, is transferred to polymer-based nanoreactors. Amphiphilic block copolymers that carry nucleobases in their hydrophobic block are self-assembled into polymersomes. The membrane of the vesicles can be transiently switched between an impermeable and a semipermeable state by shear forces occurring in flow or during turbulent mixing of polymersome dispersions. Nucleobase pairs in the hydrophobic leaflet separate when mechanical force is applied, exposing their hydrogen bonding motifs and therefore making the membrane less hydrophobic and more permeable for water soluble compounds. This polarity switch is used to release payload of the polymersomes on demand, and to activate biocatalytic reactions in the interior of the polymersomes.

Views and perceptions of Australian physiotherapists and physiotherapy students about the potential implementation of physiotherapist prescribing in Australia: a survey protocol

BACKGROUND

Non-medical prescribing (NMP) is acknowledged as an expanding area of clinical practice across the world. The physiotherapy profession is currently investigating the introduction of physiotherapist prescribing in Australia, with the case for reform centred around meeting the healthcare needs of the current and future Australian population. Conflict within a profession has been identified as a barrier to implementation of new clinical innovations. An online survey has been developed with the aim to collect and synthesise the views and perceptions of Australian physiotherapists and physiotherapy students about the potential use of NMP by physiotherapists in Australia.

METHODS

A cross-sectional descriptive survey design, using a pre-tested online questionnaire, including quantitative and qualitative components, will be utilised to explore the views and perceptions of Australian physiotherapists and physiotherapy students regarding NMP by physiotherapists in Australia. Quantitative data will be analysed descriptively and regression analysis will be utilised to identify associations between the specific question outcomes and demographic data. A thematic analytical approach will be utilised to synthesise qualitative data from open-questions.

DISCUSSION

The results from this survey will serve to inform decision-makers about the current views of the Australian physiotherapy profession with regards to the potential implementation of physiotherapist prescribing in Australia. Data will be used in conjunction with cost-benefit analyses, risk analysis as well as assessment of the health-requirements and consultation with key stakeholders including the Australian health consumer when contemplating change.

Fine-tuning timing: natural variation informs the mechanistic basis of the switch to flowering in Arabidopsis thaliana

The evolution of diverse life history strategies has allowed Arabidopsis thaliana to adapt to worldwide locations, spanning a range of latitudinal and environmental conditions. Arabidopsis thaliana accessions are either vernalization-requiring winter annuals or rapid cyclers, with extensive natural variation in vernalization requirement and response. Genetic and molecular analysis of this variation has enhanced our understanding of the mechanisms involved in life history determination, with translation to both natural and crop systems in the Brassicaceae and beyond.

Pilot study investigating the feasibility of an ulcer-specific quality of life questionnaire

Objective: This study explores the feasibility and reliability of a modified ulcer-specific quality of life (QOL) questionnaire on patients suffering from venous leg ulcers.

Methods: A cross-sectional survey was conducted on a cohort of patients suffering from venous leg ulcers who had been registered at Rochdale Infirmary to participate in a clinical trial. A self-administered six-page questionnaire – Freiburger Lebensqualitäts Questionnaire Assessment (FLQA) – on the QOL along with a checklist was used to collect data from March 2002 to June 2003. The feasibility and reliability of the venous leg ulcer specific questionnaire, the patient-reported QOL and their perspective on compression therapy were chosen as the main outcomes of the study.

Results: A response rate of 94% was obtained, of which 56% were women and 44% were men with an average age of 63 years. Approximately 72% of respondents reported that the questionnaire was suitable to reflect their perspectives on QOL and compression therapy. The questionnaire took an average of 20 minutes to complete. The average QOL score was 45.27 in all the eight domains, where 0 reflected good QOL and 100 reflected poor QOL, indicating that the respondents' QOL had been adversely affected due to venous leg ulcers. Men had an average score of 52.0 in all the eight domains and women scored 39.0 in a 0–100 scale. Hence, comparatively, men had poorer QOL than women. Reliability was assessed using measures of internal consistency and test–retest analysis. Cronbach's alpha, α = 0.934 indicated that the survey items were highly inter-correlated. Test–retest analysis indicated that there was moderate-to-strong correlation in seven out of eight domains, which meant that the reproducibility of the FLQA questionnaire was consistent.

Conclusions: The pilot survey conducted on a representative sample of patients indicated that the questionnaire is suitable and has the potential to reflect the perspective on compression therapy and overall QOL of patients suffering from venous leg ulcers. The survey tool demonstrated the clinical and research utility as a QOL outcome measure for clinical trials evaluating wound care products on patients suffering from venous leg ulcers.

Intensity-modulated radiotherapy (IMRT) to prostate and pelvic nodes-is pelvic lymph node coverage adequate with fiducial-based image-guided radiotherapy?

OBJECTIVE

There remains concern regarding the use of fiducial-based image-guided radiotherapy (IGRT) in patients with high-risk prostate cancer also undergoing intensity-modulated radiotherapy (IMRT) to pelvic nodes. By a retrospective study, we aim to ascertain the impact of the use of fiducial-based IGRT on lymph node planned target volume (PTV) coverage.

METHODS

30 consecutive IMRT prostate and pelvic node plans were reviewed, and dose was recalculated with 1-mm increment movements in anterior, posterior, superior, inferior, right and left directions up to 10 mm. All patients were treated with a full bladder after drinking 450-750 ml of water and empty rectum with the use of sodium citrate enemas daily. Dose-volume histogram parameters were recorded at each position, specifically nodal PTV V95%, V99% and V100%. A local IGRT database was used to identify the likelihood of a particular bony to fiducial offset in all directions. The combined data were used to calculate the percentage risk of underdosing the lymph node PTV on any given fraction.

RESULTS

The likelihood of an offset in the left, right and anterior directions occurring and resulting in a failure to cover the PTV was <0.25%. The likelihood of a posterior offset occurring and resulting in inadequate coverage was slightly higher but remained <1%.

CONCLUSION

This study confirms the safety of fiducial-based image-guided IMRT (IG-IMRT) with a strict bowel and bladder protocol, allowing a reduction of the clinical target volume to PTV margin of the prostate volume and consequent reduction in rectal toxicity.

ADVANCES IN KNOWLEDGE

This study strengthens the evidence supporting the safe implementation of fiducial-based IG-IMRT treating the prostate and pelvic nodes in high-risk prostate cancer.

Antibody-induced inhibition of growth of egfr overexpressing tumors occurs in the absence of receptor down-regulation

Using two antibodies which bind to distinct epitopes on the extracellular domain of the EGF receptor (EGFR) we have developed a novel method for monitoring EGFR expression and the behaviour of monoclonal antibody (mAb) bound to the receptor. We have used this method to investigate the fate of the rat mAb ICR80 following binding to the EGF receptor on tumour cells. Antibody ICR80, which was raised against the external domain of the EGF receptor on a human brain tumour (A172) cell line and was employed in this study, has the following properties. It (a) blocks the binding of EGF, TGF alpha and HB-EGF to the EGFR, (b) prevents the EGF, TGF alpha and HB-EGF induced tyrosine phosphorylation of the EGFR, and (c) inhibits the growth in vitro of the head and neck tumour (HN5) cell line overexpressing the EGF receptor. Our results presented herein also show that EGF receptor blockade by antibody ICR80 is not accompanied by detectable loss of antibody from the cell surface or down-regulation of the receptor. On the basis of these results we conclude that the long-lasting blockade of the EGF receptor on tumour cells by antibody may be an important factor in preventing the binding of growth factors which are essential for their continued proliferation.

Cannabinoid and GABA modulation of sympathetic nerve activity and blood pressure in the dorsal periaqueductal gray of the rat

Sympathoexcitation and increased blood pressure evoked by central networks integrating defensive behavior are fundamental to the acute stress response. A balance between excitatory glutamatergic and inhibitory GABAergic neurotransmission in the dorsal periaqueductal gray (dPAG) results in a tonic level of activity in the alerting system. Neuromodulators such as endocannabinoids have been shown to influence the sympathoexcitatory and pressor components of acute stress in the dPAG, exemplified by the defense response as a model, but the mechanism of integration remains unknown. The present study examines the role of GABA and its interaction with endocannabinoids in modulating sympathetic nerve activity and blood pressure related to the defense response. Microinjection of the broad-spectrum excitatory amino acid dl-homocysteic acid (DLH) identified sites of the defense pathway in the dPAG from which an increase in renal sympathetic nerve activity and blood pressure could be evoked, and subsequent microinjections were made at the same site through a multibarrelled micropipette. Blockade of GABAA receptors or microinjection of the cannabinoid 1 receptor agonist anandamide elicited a renal sympathoexcitation and pressor response. Prior microinjection of the GABAA receptor antagonist gabazine attenuated the sympathoexcitation and pressor response associated with anandamide microinjection. In contrast, the sympathetic response to DLH was enhanced by GABAA receptor blockade. These data demonstrate that sympathoexcitatory neurons in the dPAG are under tonic inhibition by GABA and that endocannabinoids modulate this GABAergic neurotransmission to help regulate components of the defense response.

Endocannabinoid modulation of sympathetic and cardiovascular responses to acute stress in the periaqueductal gray of the rat

Activation of the sympathetic nervous system is fundamental to the coordinated response to stress or danger. The midbrain periaqueductal gray (PAG) contains the neural substrate required to recruit the sympathetic nervous system and organize the physiological and behavioral responses required to respond to imposed challenges. Endocannabinoids have been shown to influence associated behavioral responses. The defense response was used in this study as a working model to examine endocannabinoid modulation of the sympathetic response to acute stress in the anesthetized rat. Microinjection of the cannabinoid 1 (CB1) receptor agonist anandamide into the defense pathway of the dorsal PAG could elicit an increase in renal sympathetic nerve activity and blood pressure, twitching of the whiskers, and movement of the limbs. The response was attenuated by prior microinjection of the CB1 receptor antagonist AM-281 at the same site. Electrical stimulation of the hypothalamic defense area could evoke similar sympathoexcitatory and pressor responses, which were significantly attenuated by microinjection of AM-281 into the dorsal PAG. These data indicate that endocannabinoids can modulate the sympathetic and cardiovascular components of the acute stress response via CB1 receptors at the level of the PAG.

Linkage and homology analysis divides the eight genes for the small subunit of petunia ribulose 1,5-bisphosphate carboxylase into three gene families

Twenty-six lambda phage clones with homology to coding sequences of the small subunit (SSU) of ribulose 1,5-bisphosphate carboxylase have been isolated from an EMBL3 lambda phage bank of Petunia (Mitchell) DNA. Restriction mapping of the phage inserts shows that the clones were obtained from five nonoverlapping regions of petunia DNA that carry seven SSU genes. Comparison of the HindIII genomic fragments of petunia DNA with the HindIII restriction fragments of the isolated phage indicates that petunia nuclear DNA encodes eight SSU genes, seven of which are present in the phage clones. Two incomplete genes, which contain only the 3' end of an SSU gene, were also found in the phage clones. We demonstrate that the eight SSU genes of petunia can be divided into three gene families based on homology to three petunia cDNA clones. Two gene families contain single SSU genes and the third contains six genes, four of which are closely linked within petunia nuclear DNA.

Loss of synaptotagmin IV results in a reduction in synaptic vesicles and a distortion of the Golgi structure in cultured hippocampal neurons

Fusion of synaptic vesicles with the plasma membrane is mediated by the SNARE (soluble NSF attachment receptor) proteins and is regulated by synaptotagmin (syt). There are at least 17 syt isoforms that have the potential to act as modulators of membrane fusion events. Synaptotagmin IV (syt IV) is particularly interesting; it is an immediate early gene that is regulated by seizures and certain classes of drugs, and, in humans, syt IV maps to a region of chromosome 18 associated with schizophrenia and bipolar disease. Syt IV has recently been found to localize to dense core vesicles in hippocampal neurons, where it regulates neurotrophin release. Here we have examined the ultrastructure of cultured hippocampal neurons from wild-type and syt IV -/- mice using electron tomography. Perhaps surprisingly, we observed a potential synaptic vesicle transport defect in syt IV -/- neurons, with the accumulation of large numbers of small clear vesicles (putative axonal transport vesicles) near the trans-Golgi network. We also found an interaction between syt IV and KIF1A, a kinesin known to be involved in vesicle trafficking to the synapse. Finally, we found that syt IV -/- synapses exhibited reduced numbers of synaptic vesicles and a twofold reduction in the proportion of docked vesicles compared to wild-type. The proportion of docked vesicles in syt IV -/- boutons was further reduced, 5-fold, following depolarization.

Systemic inflammation and disease progression in Alzheimer disease

BACKGROUND

Acute and chronic systemic inflammation are characterized by the systemic production of the proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) that plays a role in immune to brain communication. Previous preclinical research shows that acute systemic inflammation contributes to an exacerbation of neurodegeneration by activation of primed microglial cells.

OBJECTIVE

To determine whether acute episodes of systemic inflammation associated with increased TNF-alpha would be associated with long-term cognitive decline in a prospective cohort study of subjects with Alzheimer disease.

METHODS

Three hundred community-dwelling subjects with mild to severe Alzheimer disease were cognitively assessed, and a blood sample was taken for systemic inflammatory markers. Each subject's main caregiver was interviewed to assess the presence of incident systemic inflammatory events. Assessments of both patient and caregiver were repeated at 2, 4, and 6 months.

RESULTS

Acute systemic inflammatory events, found in around half of all subjects, were associated with an increase in the serum levels of proinflammatory cytokine TNF-alpha and a 2-fold increase in the rate of cognitive decline over a 6-month period. High baseline levels of TNF-alpha were associated with a 4-fold increase in the rate of cognitive decline. Subjects who had low levels of serum TNF-alpha throughout the study showed no cognitive decline over the 6-month period.

CONCLUSIONS

Both acute and chronic systemic inflammation, associated with increases in serum tumor necrosis factor alpha, is associated with an increase in cognitive decline in Alzheimer disease.

Differential endocannabinoid regulation of baroreflex-evoked sympathoinhibition in normotensive versus hypertensive rats

Previously, we found that endocannabinoids acting at cannabinoid 1 receptors in the nucleus tractus solitarius prolonged baroreflex inhibition of renal sympathetic nerve activity in normotensive Sprague Dawley rats. The current study investigated whether endocannabinoid signaling was altered in spontaneously hypertensive rats, a model marked by elevated sympathetic activity and depressed baroreflex responses. The effects of endocannabinoids in the nucleus tractus solitarius on baroreflex control of renal sympathetic nerve activity evoked by systemic pressor changes or by direct stimulation of nucleus tractus solitarius neurons, which produced depressor and sympathoinhibitory responses, were studied in Sprague Dawley rats, Wistar Kyoto rats, and spontaneously hypertensive rats. Evoked responses were compared before and after microinjection of AM404, which prolonged actions of endogenous endocannabinoids, or microinjection of an endocannabinoid, anandamide, into the baroreceptive region of the nucleus tractus solitarius. AM404 microinjections significantly prolonged evoked sympathoinhibition in Sprague Dawley and Wistar Kyoto rats, but had little effect in spontaneously hypertensive rats. Microinjections of anandamide prolonged sympathoinhibition in Sprague Dawley rats, with lesser effects in Wistar Kyoto rats and no effects in spontaneously hypertensive rats. Parallel studies found that density of binding sites of endocannabinoids in the nucleus tractus solitarius was significantly reduced in spontaneously hypertensive rats versus the normotensive rats. Results indicate that attenuated function of the endocannabinoid system in the nucleus tractus solitarius of spontaneously hypertensive rats resulted in less modulation of baroreflex-evoked sympathoinhibition and that reduced cannabinoid 1 receptor density could contribute to blunted baroreflex-induced sympathoinhibition and elevated sympathetic tone characteristic of spontaneously hypertensive rats.

Organic carbon partitioning in soil and litter in subtropical woodlands and open forests: a case study from the Brigalow Belt, Queensland

A woodland–open forest landscape within the Brigalow Belt South bioregion of Queensland, Australia, was surveyed for soil organic carbon, soil bulk density and soil-surface fine-litter carbon. Soil carbon stocks to 30 cm depth across 14 sites, spanning a range of soil and vegetation complexes, ranged from 10.7 to 61.8 t C/ha, with an overall mean of 36.2 t C/ha. Soil carbon stocks to 100 cm depth ranged from 19.4 to 150.5 t C/ha, with an overall mean of 72.9 t C/ha. The standing stock of fine litter ranged from 1.0 to 7.0 t C/ha, with a mean of 2.6 t C/ha, and soil bulk density averaged 1.4 g/cm3 at the soil surface, and 1.6 g/cm3 at 1 m depth. These results contribute to the currently sparse database of soil organic carbon and bulk density measurements in uncultivated soils within Australian open forests and woodlands. The estimates of total soil organic carbon stock calculated to 30 cm depth were further partitioned into resistant plant material (RPM), humus (HUM), and inert organic matter (IOM) pools using diffuse mid-infrared (MIR) analysis. Prediction of the HUM and RPM pools using the RothC soil carbon model agreed well with the MIR measurements, confirming the suitability of RothC for modelling soil organic carbon in these soils. Methods for quantifying soil organic carbon at landscape scales were also explored, and a new regression-based technique for estimating soil carbon stocks from simple field-measured soil attributes has been proposed. The results of this study are discussed with particular reference to the difficulties encountered in the collection of the data, their limitations, and opportunities for the further development of methods for quantifying soil organic carbon at landscape scales.

Additional targets of the Arabidopsis autonomous pathway members, FCA and FY

A central player in the Arabidopsis floral transition is the floral repressor FLC, the MADS-box transcriptional regulator that inhibits the activity of genes required to switch the meristem from vegetative to floral development. One of the many pathways that regulate FLC expression is the autonomous promotion pathway composed of FCA, FY, FLD, FPA, FVE, LD, and FLK. Rather than a hierarchical set of activities the autonomous promotion pathway comprises sub-pathways of genes with different biochemical functions that all share FLC as a target. One sub-pathway involves FCA and FY, which interact to regulate RNA processing of FLC. Several of the identified components (FY, FVE, and FLD) are homologous to yeast and mammalian proteins with rather generic roles in gene regulation. So why do mutations in these genes specifically show a late-flowering phenotype in Arabidopsis? One reason, found during the analysis of fy alleles, is that the mutant alleles identified in flowering screens can be hypomorphic, they still have partial function. A broader role for the autonomous promotion pathway is supported by a microarray analysis which has identified genes mis-regulated in fca mutants, and whose expression is also altered in fy mutants.

Sympathoinhibition from ventrolateral periaqueductal gray mediated by the caudal midline medulla

Activation of neurons in the ventrolateral region of the periaqueductal gray (vlPAG) can elicit a decrease in renal sympathetic nerve activity and blood pressure. The present study investigated whether the vlPAG-evoked sympathoinhibitory response depends on neurons in the caudal midline medulla (CMM). In pentobarbital-anesthetized rats, activation of neurons in the vlPAG evoked a decrease in renal sympathetic nerve activity to 29.4 ± 4.8% below baseline levels and arterial blood pressure fell 8.9 ± 1.6 mmHg ( n = 20). Microinjection of the GABA agonist muscimol into sympathoinhibitory regions of the CMM significantly attenuated the vlPAG-evoked sympathoinhibition to 17.9 ± 4.1% below baseline and the depressor response to 4.3 ± 1.2 mmHg. At 65% (13/20) of the sites examined, the vlPAG-evoked sympathoinhibition was responsive to CMM muscimol microinjection and attenuated from 34.2% to 11.5%, with the depressor response reduced from 14.8 to 3 mmHg. Microinjection of muscimol at the remaining 35% of the CMM sympathoinhibitory sites was ineffective on the vlPAG-evoked sympathoinhibition and depressor response. These data indicate that sympathoinhibitory and hypotensive responses elicited by activation of neurons in the vlPAG can be mediated by neurons in the sympathoinhibitory region of the CMM. The finding that the vlPAG-evoked response is not affected by muscimol at all CMM sympathoinhibitory sites also suggests that sympathoinhibitory sites in the CMM are not homogeneous and can mediate functionally different responses.

Subtype Composition and Responses of Respiratory Neurons in the Pre-Bötzinger Region to Pulmonary Afferent Inputs in Dogs

The brain stem pre-Bötzinger complex (pre-BC) plays an important role in respiratory rhythm generation. However, it is not clear what function each subpopulation of neurons in the pre-BC serves. The purpose of the present studies was to identify neuronal subpopulations of the canine pre-BC and to characterize the neuronal responses of subpopulations to experimentally imposed changes in inspiratory (I) and expiratory (E) phase durations. Lung inflations and electrical stimulation of the cervical vagus nerve were used to produce changes in respiratory phase timing via the Hering-Breuer reflex. Multibarrel micropipettes were used to record neuronal activity and for pressure microejection in decerebrate, paralyzed, ventilated dogs. The pre-BC region was functionally identified by eliciting tachypneic phrenic neural responses to localized microejections of dl-homocysteic acid. Antidromic stimulation and spike-triggered averaging techniques were used to identify bulbospinal and cranial motoneurons, respectively. The results indicate that the canine pre-BC region consists of a heterogeneous mixture of propriobulbar I and E neuron subpopulations. The neuronal responses to ipsi-, contra-, and bilateral pulmonary afferent inputs indicated that I and E neurons with decrementing patterns were the only neurons with responses consistently related to phase duration. Late-I neurons were excited, but most other types of I neurons were inhibited or unresponsive. E neurons with augmenting or parabolic discharge patters were inhibited by ipsilateral inputs but excited by contra- and bilateral inputs. Late-E neurons were more frequently encountered and were inhibited by ipsi- and bilateral inputs, but excited by contralateral inputs. The results suggest that only a limited number of neuron subpopulations may be involved in rhythmogenesis, whereas many neuron types may be involved in motor pattern generation.

RNA processing and Arabidopsis flowering time control

Plants control their flowering time in order to ensure that they reproduce under favourable conditions. The components involved in this complex process have been identified using a molecular genetic approach in Arabidopsis and classified into genetically separable pathways. The autonomous pathway controls the level of mRNA encoding a floral repressor, FLC, and comprises three RNA-binding proteins, FCA, FPA and FLK. FCA interacts with the 3'-end RNA-processing factor FY to autoregulate its own expression post-transcriptionally and to control FLC. Other components of the autonomous pathway, FVE and FLD, regulate FLC epigenetically. This combination of epigenetic and post-transcriptional control gives precision to the control of FLC expression and flowering time.

The efficacy of donepezil in the treatment of neuropsychiatric symptoms in Alzheimer disease

OBJECTIVE

To determine the efficacy of donepezil in the treatment of neuropsychiatric symptoms in patients with Alzheimer disease (AD) in a randomized withdrawal study.

METHOD

Patients with mild to moderate AD with marked neuropsychiatric symptoms at baseline (Neuropsychiatric Inventory [NPI] > 11 points) were treated openly with donepezil 5 mg daily for 6 weeks followed by 10 mg daily for a further 6 weeks. Patients were then randomized (60:40) to either placebo or 10 mg donepezil daily. All patients were assessed at 6 weeks and provided there was no marked cognitive deterioration their blinded treatment was continued for a further 6 weeks. NPI and carer distress were assessed at 6 weekly intervals throughout the study.

RESULTS

A total of 134 patients participated. Following randomization patients who continued on donepezil 10 mg for 12 weeks had improvements in NPI compared with the placebo group (mean change -2.9 vs 3.3 points; ITT-LOCF p = 0.02) and in NPI-Distress scores (median change -2.0 vs 1.0 points; ITT-LOCF p = 0.01). During the open-label phase the total NPI and NPI-Distress scores were lower after 12 weeks treatment with open label donepezil compared with baseline (total NPI 22 points vs13 points; ITT-LOCF p < 0.0001; NPI-Distress 13.5 vs 7.9 points; ITT-LOCF p < 0.0001). In the open-label phase all domains of the NPI (with the exception of elation) were improved (all p < 0.05 after Bonferroni correction).

CONCLUSIONS

Donepezil has significant efficacy in the treatment of neuropsychiatric symptoms in patients with mild to moderate AD.

Serotonergic neurons of the caudal raphe nuclei activated in response to hemorrhage in the rat

The response to a sudden, severe loss of blood volume is complex and results in a drastic fall in arterial blood pressure and sympathoinhibition. The present study examines the distribution of serotonergic neurons in the caudal raphe involved in the mediation of the response to severe hemorrhage. Hemorrhage was performed in rats anesthetised with urethane by withdrawal of blood at a rate of 1 ml/min for approximately 4 min until blood pressure fell to 50 mm Hg. Sections through the brainstem were processed immunohistochemically to identify Fos, the protein product of the proto-oncogene c-fos expressed in the nucleus of neurons activated during the hemorrhage stimulus, and double-labeled to identify serotonin (5-hydroxytryptamine; 5-HT) content of cells. In response to hemorrhage, double-labeled Fos/5-HT neurons were located in the B3 region which includes the raphe magnus (RM) and its lateral extension. Hemorrhage-induced Fos-positive neurons that were not serotonergic were located in raphe pallidus (RP), parapyramidal cell group (PP), and the B3 region. Serotonergic neurons not activated by hemorrhage were located in the nucleus raphe pallidus, the parapyramidal cell group, the raphe obscurus (RO), and the B3 region. The specific rostrocaudal distribution of activated neurons may indicate different functions of groups of neurons in the response to hemorrhage.

Serologic evidence for West Nile virus infection in birds in Staten Island, New York, after an outbreak in 2000

After an outbreak of West Nile virus (WNV) infections in people, horses, and wildlife in Staten Island, NY, during the summer of 2000, we surveyed the bird population of the island for evidence of infection. Neutralizing antibodies were detected in 59 of 257 (23.0%) resident birds and none of 96 transient (migrating) birds sampled in early October. Species with the greatest seroprevalence were northern cardinal (Cardinalis cardinalis) (69.2%) and rock dove (Columba livia) (54.5%). House sparrows (Passer domesticus) and chickens (Gallus gallus) had lower than expected seroprevalences, 8.6% and 5.5%, respectively. The geographic distribution of seropositivity suggested focal transmission at several locations on the island. The concentration of seropositive birds among resident bird populations on Staten Island supports the concept that many birds survive WNV infection and that some of these play an important role in the WNV-bird-mosquito transmission cycle.

Activity-dependent role of NMDA receptors in transmission of cardiac mechanoreceptor input to the NTS

Evidence suggests that transmission of barosensitive input from arterial baroreceptors and cardiac mechanoreceptors at nucleus tractus solitarius (NTS) neurons involves non-N-methyl-d-aspartate (NMDA) glutamate receptors, but there is a possibility that the contribution of NMDA receptors might increase during periods of increased afferent input, when enhanced neuronal depolarization could increase the activation of NMDA receptors by removal of a Mg(2+) block. Thus the effects of NMDA on cardiac mechanoreceptor-modulated NTS neuronal discharges were examined at different levels of arterial pressure used to change cardiac mechanoreceptor afferent input. To determine whether the response was specific to NMDA, (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA) was also administered at different levels of neuronal discharge. In anesthetized dogs, neuronal activity was recorded from the NTS while NMDA or AMPA was picoejected at high versus low arterial stimulating pressures. NMDA, but not AMPA, produced a significantly greater discharge of mechanoreceptor-driven NTS neurons at higher versus lower levels of stimulating pressure. These data suggest that the role played by NMDA receptors is greater during periods of enhanced neuronal depolarization, which could be produced by increases in afferent barosensitive input.