Situating the parietal memory network in the context of multiple parallel distributed networks using high-resolution functional connectivity

A principle of brain organization is that networks serving higher cognitive functions are widely distributed across the brain. One exception has been the parietal memory network (PMN), which plays a role in recognition memory but is often defined as being restricted to posteromedial association cortex. We hypothesized that high-resolution estimates of the PMN would reveal small regions that had been missed by prior approaches. High-field 7T functional magnetic resonance imaging (fMRI) data from extensively sampled participants was used to define the PMN within individuals. The PMN consistently extended beyond the core posteromedial set to include regions in the inferior parietal lobule; rostral, dorsal, medial, and ventromedial prefrontal cortex; the anterior insula; and ramus marginalis of the cingulate sulcus. The results suggest that, when fine-scale anatomy is considered, the PMN matches the expected distributed architecture of other association networks, reinforcing that parallel distributed networks are an organizing principle of association cortex.

GAP43-dependent mitochondria transfer from astrocytes enhances glioblastoma tumorigenicity

The transfer of intact mitochondria between heterogeneous cell types has been confirmed in various settings, including cancer. However, the functional implications of mitochondria transfer on tumor biology are poorly understood. Here we show that mitochondria transfer is a prevalent phenomenon in glioblastoma (GBM), the most frequent and malignant primary brain tumor. We identified horizontal mitochondria transfer from astrocytes as a mechanism that enhances tumorigenesis in GBM. This transfer is dependent on network-forming intercellular connections between GBM cells and astrocytes, which are facilitated by growth-associated protein 43 (GAP43), a protein involved in neuron axon regeneration and astrocyte reactivity. The acquisition of astrocyte mitochondria drives an increase in mitochondrial respiration and upregulation of metabolic pathways linked to proliferation and tumorigenicity. Functionally, uptake of astrocyte mitochondria promotes cell cycle progression to proliferative G2/M phases and enhances self-renewal and tumorigenicity of GBM. Collectively, our findings reveal a host-tumor interaction that drives proliferation and self-renewal of cancer cells, providing opportunities for therapeutic development.

WDR5 represents a therapeutically exploitable target for cancer stem cells in glioblastoma

Glioblastomas (GBMs) are heterogeneous, treatment-resistant tumors driven by populations of cancer stem cells (CSCs). However, few molecular mechanisms critical for CSC population maintenance have been exploited for therapeutic development. We developed a spatially resolved loss-of-function screen in GBM patient-derived organoids to identify essential epigenetic regulators in the SOX2-enriched, therapy-resistant niche and identified WDR5 as indispensable for this population. WDR5 is a component of the WRAD complex, which promotes SET1 family-mediated Lys4 methylation of histone H3 (H3K4me), associated with positive regulation of transcription. In GBM CSCs, WDR5 inhibitors blocked WRAD complex assembly and reduced H3K4 trimethylation and expression of genes involved in CSC-relevant oncogenic pathways. H3K4me3 peaks lost with WDR5 inhibitor treatment occurred disproportionally on POU transcription factor motifs, including the POU5F1(OCT4)::SOX2 motif. Use of a SOX2/OCT4 reporter demonstrated that WDR5 inhibitor treatment diminished cells with high reporter activity. Furthermore, WDR5 inhibitor treatment and WDR5 knockdown altered the stem cell state, disrupting CSC in vitro growth and self-renewal, as well as in vivo tumor growth. These findings highlight the role of WDR5 and the WRAD complex in maintaining the CSC state and provide a rationale for therapeutic development of WDR5 inhibitors for GBM and other advanced cancers.

Distinct Cell Adhesion Signature Defines Glioblastoma Myeloid-Derived Suppressor Cell Subsets

In multiple types of cancer, an increased frequency in myeloid-derived suppressor cells (MDSC) is associated with worse outcomes and poor therapeutic response. In the glioblastoma (GBM) microenvironment, monocytic (m) MDSCs represent the predominant subset. However, the molecular basis of mMDSC enrichment in the tumor microenvironment compared with granulocytic (g) MDSCs has yet to be determined. Here we performed the first broad epigenetic profiling of MDSC subsets to define underlying cell-intrinsic differences in behavior and found that enhanced gene accessibility of cell adhesion programs in mMDSCs is linked to their tumor-accelerating ability in GBM models upon adoptive transfer. Mouse and human mMDSCs expressed higher levels of integrin β1 and dipeptidyl peptidase-4 (DPP-4) compared with gMDSCs as part of an enhanced cell adhesion signature. Integrin β1 blockade abrogated the tumor-promoting phenotype of mMDSCs and altered the immune profile in the tumor microenvironment, whereas treatment with a DPP-4 inhibitor extended survival in preclinical GBM models. Targeting DPP-4 in mMDSCs reduced pERK signaling and their migration towards tumor cells. These findings uncover a fundamental difference in the molecular basis of MDSC subsets and suggest that integrin β1 and DPP-4 represent putative immunotherapy targets to attenuate myeloid cell-driven immune suppression in GBM.

SIGNIFICANCE

Epigenetic profiling uncovers cell adhesion programming as a regulator of the tumor-promoting functions of monocytic myeloid-derived suppressor cells in glioblastoma, identifying therapeutic targets that modulate the immune response and suppress tumor growth.

IMMU-17. LEVERAGING CORE EPIGENETIC PROGRAMMING OF IMMUNOSUPPRESSIVE MYELOID CELLS FOR THERAPEUTIC TARGETING OF GLIOBLASTOMA

Accumulation of various immunosuppressive myeloid cells, including myeloid-derived suppressor cells (MDSCs), facilitates progression and treatment resistance of glioblastoma (GBM). We previous demonstrated that monocytic MDSCs (mMDSCs) but not granulocytic MDSCs (gMDSCs) infiltrate tumors in mouse models and patients, and that nonspecific targeting of mMDSCs with chemotherapies provided therapeutic benefit in preclinical models of GBM. To investigate the differential role and trafficking of mMDSCs versus gMDSCs in GBM, we adoptively transferred these cells into tumor-bearing mice. Mice that received mMDSCs succumbed to disease at an earlier point compared to control mice or mice that received gMDSCs. To delineate the cellular basis of this distinct behavior of MDSC subsets, we performed assay for transposase-accessible chromatin using sequencing (ATAC-seq) and observed that cell adhesion-related genes were significantly enriched in open chromatin regions of mMDSCs as opposed to gMDSCs. Aligned with this epigenetic profile, mMDSCs from blood and tumors had significantly higher surface integrin β1 expression compared to gMDSCs in both mouse models and GBM patients. To evaluate the functional role of these integrins, we pre-treated mMDSCs with anti-integrin β1 prior to adoptive transfer. Blockade of surface integrin β1 interfered with the pro-tumorigenic role of mMDSCs, as the survival span of mice receiving these cells was similar to that of vehicle controls. Further analysis of the ATAC-Seq data revealed that dipeptidyl peptidase-4 (Dpp4), an interacting partner of integrin β1, was more accessible in mMDSCs compared to gMDSC. Consistently, bone marrow-derived mMDSCs in mouse and tumor-infiltrating mMDSCs in GBM patients expressed high levels of Dpp4. Pharmacological inhibition of Dpp4 reduced chemotaxis of mMDSCs in vitro and extended survival duration of mice with tumors. The findings from this study have broad implications across cancer types to modulate immunosuppressive myeloid cells by leveraging these novel insights into their adhesion mechanisms.

TMIC-69. MITOCHONDRIAL TRANSFER FROM ASTROCYTES ENHANCES METABOLISM AND DRIVES PROLIFERATION OF GLIOBLASTOMA

Mitochondrial transfer occurs both in stroke (central nervous system) and inflammatory pain (peripheral nerves). However, its role in glioblastoma (GBM) remains poorly understood. We hypothesized that mitochondrial transfer from non-malignant to GBM cells supports tumor metabolism and growth. Using transgenic mice expressing fluorophore-tagged mitochondria, we found that ~50% of orthotopically-implanted mouse GBM cells acquire mitochondria. Brain-resident cells, especially astrocytes, were the primary mitochondrial donors in vitro and in vivo. Mitochondrial transfer also occurred from immortalized human astrocytes to patient-derived xenograft (PDX) models in vitro at rates of 15-35%. GBM cells that acquired mitochondria expressed higher levels of the ATP-synthase subunit ATP5A and produced more ATP, while metabolomics revealed multiple upregulated pathways in recipient cells. These data point to increased metabolic activity in recipient cells. In vivo, mouse GBM cells that acquired mitochondria were more likely to be in S/G2/M cell cycle phases. We observed a similar effect in PDX that acquired astrocyte mitochondria in vitro, suggesting that transfer drives GBM proliferation. Using sorted mouse and human GBM cells with/without in vitro astrocyte mitochondrial acquisition, we found that mitochondrial transfer promoted in vitro self-renewal and in vivo tumorigenicity, leading to significant reduction in survival and increased penetrance in orthotopic GBM models. Transfer in mouse and human systems was contact-dependent and was abrogated by physical separation of donor and recipient cells by transwell inserts. Pharmacologic inhibition of cytoskeleton and gap junctions did not affect transfer rate, while blocking growth-associated protein 43 (GAP43) function by c-Jun N-terminus kinase inhibition decreased transfer rate by 15-30%, suggesting a potential role of GAP43. Taken together, mitochondrial transfer comprises a fundamental, protumorigenic mechanism of GBM, enhancing metabolic activity and driving tumor cell proliferation. Elucidating the molecular machinery regulating astrocyte mitochondrial transfer and its downstream protumorigenic effects will lead to therapeutic opportunities targeting this understudied tumor microenvironment interaction.

IMMU-32. SPERMIDINE DRIVES GLIOBLASTOMA PROGRESSION VIA SELECTIVE MODULATION OF THE IMMUNE SYSTEM

Glioblastoma (GBM) is incurable despite aggressive standard of care treatments (maximal safe surgical resection, radiation, chemotherapy). GBM therapeutic resistance is due to multiple factors, including tumor heterogeneity and a highly immunosuppressive environment. Naturally occurring polyamines have been identified as a putative therapeutic target in other cancers based on their increased presence and function in normal conditions; they are critical for cell growth and proliferation and cellular functions including autophagy and apoptosis. While polyamines are increased in GBM patients, little is known about their impact on GBM growth. In syngeneic immune competent mouse glioma models (GL261, SB28), mass spectrometry data revealed that spermidine (SPD) – a member of the polyamine family – is increased in tumor tissue as compared to non-neoplastic control brain tissue (sham implanted animals). To test the impact of SPD on tumor growth, we treated mouse glioma models with exogenous SPD and found treatment significantly decreased survival. However, in immunocompromised host mice, no such difference was observed, indicating the mechanism through which SPD is driving GBM progression likely involves immune system alterations. Depletion of myeloid derived suppressor cells in vivo via anti-Gr-1 antibody rescues the decrease in survival caused by exogenous SPD, indicating that SPD drives GBM by affecting immune-suppressive cell subsets, namely MDSCs. To assess if SPD is associated with more aggressive GBM growth in human patients, we are currently analyzing polyamine levels in human GBM samples of long vs short term survivors. We are also exploring the effect of dietary polyamines on GBM via the gut-brain-microbiome axis, as polyamines are enriched in many foods and produced by a subset of commensal gut microbes. Understanding the interactions between polyamines, the tumor microenvironment, and the immune response provide a new mechanism for GBM regulation and identify opportunities to alter the environment in the body to enhance immunotherapeutic efficacy.

IMMU-21. DIFFERENTIAL EXPRESSION OF ADHESION MOLECULES DEFINES MYELOID CELL INFILTRATION IN GLIOBLASTOMA AND COMPRISES A THERAPEUTIC TARGET

A potently immunosuppressive tumor microenvironment facilitates progression of glioblastoma (GBM). Immunotherapies have had variable success in improving the outcome of GBM patients, suggesting that there is a need to gain insight into the mechanisms of immunosuppression. Myeloid-derived suppressor cells (MDSCs) associate with poor prognosis and treatment resistance of GBM patients, but the distinct role of individual populations is not well-defined. We previous showed that monocytic MDSCs (mMDSCs) accumulated in tumors of mice and patients, while granulocytic MDSCs (gMDSCs) mainly remained in the circulation. Furthermore, nonspecific targeting of mMDSCs with chemotherapies provided therapeutic benefit in preclinical models of GBM, suggesting that mMDSCs drive disease progression. To investigate the differential function of mMDSCs versus gMDSCs in GBM, we adoptively transferred bone marrow-derived MDSC subsets into tumor-bearing mice. Mice that received mMDSCs succumbed to disease sooner compared to control mice, which was not observed with gMDSC transfer. To determine the basis of this pro-tumorigenic activity of mMDSCs, we performed ATAC-sequencing and comparison of differentially accessible regions indicated that cell adhesion pathways were significantly upregulated in mMDSCs. Aligned with this epigenetic profile, mMDSCs from bone marrow and blood had significantly higher surface integrin β1 and integrin β7 expression compared to gMDSCs. To evaluate the role of integrins in MDSC behavior, we pre-treated mMDSCs with anti-integrin β1 prior to adoptive transfer. Blockade of integrin β1 interfered with the pro-tumorigenic role of mMDSCs compared to isotype controls. Similarly, blockade of integrin β1 and integrin β7 systemically extended the survival duration of tumor-bearing mice. Finally, high expression of integrin β1 and integrin β7 served as a poor prognostic indicator in GBM patients. Our findings indicate that modulation of immunosuppressive myeloid cells by leveraging differences in adhesion mechanisms represents a potential immunotherapeutic option for GBM.

STEM-14. THE WRAD COMPLEX REPRESENTS A THERAPEUTIC TARGET FOR CANCER STEM CELLS IN GLIOBLASTOMA

Glioblastoma (GBM) progression and resistance to conventional therapies is driven in part by cells within the tumor with stem cell properties including quiescence, self-renewal and drug efflux potential. It is thought that eliminating these cancer stem cells (CSCs) is a key component to successful clinical management of GBM. However, currently, few known molecular mechanisms driving CSCs can be exploited for therapeutic development. Core transcription factors such as SOX2, OLIG2, OCT4 and NANOG maintain the CSC state in GBM. Our laboratory recently uncovered a self-renewal signaling axis involving RBBP5 that is necessary and sufficient for CSC maintenance through driving expression of these core stem cell maintenance transcription factors. RBBP5 is a component of the WRAD complex, which promotes Lys4 methylation of histone H3 to positively regulate transcription. We hypothesized that targeting RBBP5 could be a means to disrupt epigenetic programs that maintain CSCs in stemness transcriptional states. We found that genetic and pharmacologic inhibition of the WRAD complex reduced CSC growth, self-renewal and tumor initiation potential. WRAD inhibitors partially dissembled the WRAD complex and reduced H3K4 trimethylation both globally and at the promoters of key stem cell maintenance transcription factors. Using a CSC reporter system, we demonstrated that WRAD complex inhibition decreased growth of SOX2/OCT4 expressing CSCs in a concentration-dependent manner as quantified by live imaging. Overall, our studies assess the function of the WRAD complex and the effect of WRAD complex inhibitors in preclinical models and specifically on the stem cell state for the first time in GBM. Studying the functions of the WRAD complex in CSCs may improve understanding of GBM pathogenesis and elucidate how CSCs survive despite aggressive chemotherapy and radiation. Our ongoing studies aim to develop brain penetrant inhibitors targeting the WRAD complex as an anti-CSC strategy that could potentially synergize with standard of care treatments.

Sex Differences in Glioblastoma Immunotherapy Response

Glioblastoma (GBM), the most common primary malignant brain tumor, remains difficult to treat and shares phenotypes, including an aberrant immune response, with other neurological disorders. Understanding the cellular and molecular mechanisms underlying this pathological immune response remains a priority, particularly as standard of care for advanced cancers evolves to include immunotherapies, which have yet to show strong clinical efficacy in GBM. Epidemiological evidence supports a sex difference in GBM, with increased prevalence in males, and recent studies identified differences between males and females ranging from genetic aberrations to cellular programs. Sex differences have also been identified in immune response, and in this mini-review, we present these differences to highlight potential sex-specific cellular and molecular mechanisms that underly GBM growth and response to immunotherapies. These sex differences offer an opportunity to understand GBM pathogenesis and extend beyond GBM to other tumors and neurological disorders to inform the development of next-generation therapies.

Salivary proteins alter taste-guided behaviors and taste nerve signaling in rat

Taste stimuli are normally dissolved in saliva prior to interacting with their respective receptor targets. There are hundreds of proteins in saliva, and it has been hypothesized that these proteins could interact with either taste stimuli or taste receptors to alter taste signaling and diet acceptance. However, the impact of these proteins on feeding has been relatively unexplored using rodent models. We have developed a novel technique for saliva collection that allows us to link salivary protein expression with feeding behavior. First, we monitored the microstructure of rats' feeding patterns on a 0.375% quinine diet (Q-diet) while tracking changes in salivary protein expression. We found 5 protein bands were upregulated by diet exposure to Q-diet and upregulation of a subset of these bands were statistically related to increased diet acceptance, including changes in behavioral measures that are thought to represent both orosensory and postingestive signaling. In a second experiment, we measured the licking to a range of quinine solutions (0.01-1.0mM) before and after the animals were exposed to a tannic acid diet that altered salivary protein expression. Rats found the quinine solutions less aversive after salivary protein altering diets. In a third experiment we recorded the response of the chorda tympani (CT) nerve while delivering quinine solutions (0.3-30mM) to the front of the tongue dissolved in either "donor saliva" containing salivary proteins or donor saliva which has had the salivary proteins removed. Donor saliva was collected from a separate group of animals using isoproterenol and pilocarpine. The samples containing salivary proteins resulted in lower nerve responses than those without salivary proteins. Together these data suggest that salivary proteins are capable of altering taste-guided behaviors and taste nerve signaling.

Pollinator-mediated assemblage processes in California wildflowers

Community assembly is the result of multiple ecological and evolutionary forces that influence species coexistence. For flowering plants, pollinators are often essential for plant reproduction and establishment, and pollinator-mediated interactions may influence plant community composition. Here, we use null models and community phylogenetic analyses of co-occurrence patterns to determine the role of pollinator-mediated processes in structuring plant communities dominated by congeners. We surveyed three species-rich genera (Limnanthes, Mimulus and Clarkia) with centres of diversity in the Sierra Nevada of California. Each genus contains species that co-flower and share pollinators, and each has a robust phylogeny. Within each genus, we surveyed 44-48 communities at three spatial scales, measured floral and vegetative traits and tested for segregation or aggregation of: (i) species, (ii) floral traits (which are likely to be influenced by pollinators), and (iii) vegetative traits (which are likely affected by other environmental factors). We detected both aggregation and segregation of floral traits that were uncorrelated with vegetative trait patterns; we infer that pollinators have shaped the community assembly although the mechanisms may be varied (competition, facilitation, or filtering). We also found that mating system differences may play an important role in allowing species co-occurrence. Together, it appears that pollinators influence community assemblage in these three clades.

Hindbrain orexin 1 receptors influence palatable food intake, operant responding for food, and food-conditioned place preference in rats

RATIONALE

Brain orexin 1 receptors (OX1Rs) are involved in food-motivated behavior. Most research has focused on forebrain OX1R populations, but hindbrain OX1Rs affect feeding. We hypothesized that hindbrain OX1Rs affect the reward value of food.

OBJECTIVES

We examined the effects of hindbrain OX1R stimulation or blockade on motivation for food, palatable high-fat (HF) food intake, and food-conditioned place preference.

METHODS

Rats trained to lever press for sucrose on a progressive ratio (PR) schedule received fourth intracerebroventricular (icv) injections of vehicle, orexin-A (0.1-1 nmol), or the OX1R antagonist SB334867 (10-20 nmol) before operant test sessions. Effects of these treatments on HF food intake during daily 1-h tests were assessed with fourth icv and nucleus of the solitary tract (NTS) injections. We conditioned a place preference by pairing HF food with one side of a two-sided chamber and then examined the effect of 20 nmol fourth icv SB334867 on the expression of that preference.

RESULTS

In ad lib fed rats on the PR schedule, fourth icv orexin-A significantly increased responding and breakpoint relative to the vehicle. In 24-h food-deprived rats, fourth icv SB334867 significantly decreased responding and breakpoint. Orexin-A delivered to the fourth ventricle (0.1 nmol) or NTS (0.01 nmol) increased HF diet intake. Fourth icv SB334867 did not affect HF food intake, but SB334867 delivered either fourth icv (20 nmol) or intra-NTS (5-10 nmol) suppressed chow intake. Expression of HF food-conditioned place preference was inhibited by fourth icv SB334867.

CONCLUSIONS

Hindbrain OX1R activity affects food-motivated operant behavior and may play a role in responding to cues that predict palatable food.

Determination of 5-log reduction times for Escherichia coli O157:H7, Salmonella enterica, or Listeria monocytogenes in acidified foods with pH 3.5 or 3.8 3

A critical factor in ensuring the safety of acidified foods is the establishment of a thermal process that assures the destruction of acid-resistant vegetative pathogenic and spoilage bacteria. For acidified foods such as dressings and mayonnaises with pH values of 3.5 or higher, the high water phase acidity (acetic acid of 1.5 to 2.5% or higher) can contribute to lethality, but there is a lack of data showing how the use of common ingredients such as acetic acid and preservatives, alone or in combination, can result in a 5-log reduction for strains of Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in the absence of a postpackaging pasteurization step. In this study, we determined the times needed at 10° C to achieve a 5-log reduction of E. coli O157:H7, S. enterica, and L. monocytogenes in pickling brines with a variety of acetic and benzoic acid combinations at pH 3.5 and 3.8. Evaluation of 15 different acid-pH combinations confirmed that strains of E. coli O157:H7 were significantly more acid resistant than strains of S. enterica and L. monocytogenes. Among the acid conditions tested, holding times of 4 days or less could achieve a 5-log reduction for vegetative pathogens at pH 3.5 with 2.5% acetic acid or at pH 3.8 with 2.5% acetic acid containing 0.1% benzoic acid. These data indicate the efficacy of benzoic acid for reducing the time necessary to achieve a 5-log reduction in target pathogens and may be useful for supporting process filings and the determination of critical controls for the manufacture of acidified foods.

Nucleus accumbens GLP-1 receptors influence meal size and palatability

Recent evidence suggests that the glucagon-like peptide-1 (GLP-1) neuronal projection to the nucleus accumbens core (NAcC) contributes to food intake control. To investigate the role of endogenous stimulation of GLP-1 receptors (GLP-1R) in NAcC, we examined the effects of the GLP-1R antagonist exendin-(9-39) (Ex9) on meal pattern and microstructure of ingestive behavior in rats. Intra-NAcC Ex9 treatment selectively increased meal size relative to vehicle in rats consuming 0.25 M sucrose solution or sweetened condensed milk. Microstructural analysis revealed effects of NAcC Ex9 on initial lick rate and the size and duration of licking bursts in rats consuming 0.1 or 0.25 M sucrose, suggesting that blockade of NAcC GLP-1R increases palatability. Because NAcC Ex9 did not affect licking for nonnutritive saccharin (0.1%), we suggest that the presence of nutrients in the gut may be required for endogenous stimulation of NAcC GLP-1R. Consistent with this, we also found that the meal size-suppressive effects of intragastric nutrient infusion were attenuated by NAcC delivery of Ex9 at a dose that had no effect when delivered alone. Analysis of licking patterns revealed that NAcC Ex9 did not reverse intragastric nutrient-induced suppression of burst number but rather blunted the effect of nutrient infusion on meal size primarily by increasing the size and duration of licking bursts. Together, our results suggest that NAcC Ex9 influences taste evaluation. We conclude that GLP-1 released in NAcC in response to gastrointestinal nutrients reduces the hedonic value of food.

Oxytocin action in the ventral tegmental area affects sucrose intake

Brain oxytocin is known to play a role in the control of food intake, and recent studies suggest that stimulation of central oxytocin receptors selectively suppresses carbohydrate intake. The specific oxytocin projection sites and receptor populations involved in this response are as yet unidentified. We hypothesized that oxytocin receptors in the ventral tegmental area (VTA) may play a role in limiting sucrose intake, because the VTA is known to influence palatable food intake. We first performed a dose response study in which we observed that intra-VTA oxytocin injection significantly suppressed intake of a 10% sucrose solution during a 30-min test session by 13.35-20.5% relative to vehicle treatment. Doses of intra-VTA oxytocin that suppressed sucrose intake had no effect on water intake. Next we examined the effects of two oxytocin receptor antagonists, (d(CH2)5(1),Tyr(Me)(2),Orn(8))-Oxytocin (OVT) and L-368,899. Each of these antagonists significantly increased 10% sucrose intake by 17-20.5% relative to vehicle when delivered directly into the VTA, at doses subthreshold for effect if injected into the cerebral ventricles. Finally, we observed that the effect of intra-VTA oxytocin to suppress 10% sucrose intake was significantly attenuated by pretreatment with L-368,899, supporting the suggestion that the VTA oxytocin treatment suppresses intake through action at oxytocin receptors. These findings support the suggestion that endogenous oxytocin action within the VTA suppresses sucrose intake. We conclude that oxytocin receptors in the VTA play a physiologic role in the control of sucrose ingestion.

Evidence for the role of hindbrain orexin-1 receptors in the control of meal size

Hypothalamic orexin neurons project to the hindbrain, and 4th-ventricle intracerebroventricular (4th-icv) injection of orexin-A treatment increases food intake. We assessed the effects of hindbrain orexin-A and the orexin-1-receptor antagonist SB334867 on meal pattern in rats consuming standard chow. When injected 4th-icv shortly before dark onset, lower doses of orexin-A increased food intake over a 2-h period by increasing the size of the first meal relative to vehicle, whereas the highest dose increased food intake by causing the second meal to be taken sooner. Conversely, hindbrain SB334867 reduced food intake by decreasing the size of the first meal of the dark phase. We also examined the effects of 4th-icv orexin-A and SB334867 on locomotor activity. Only the highest dose of orexin-A increased activity, and SB334867 had no effect. In addition, hindbrain SB334867 induced c-Fos in the nucleus of the solitary tract. These data support the suggestion that endogenous hindbrain orexin-A acts to limit satiation. Both orexin-A and the pancreatic satiation hormone amylin require an intact area postrema to affect food intake, so we asked whether 4th-icv orexin-A impairs the satiating effect of peripheral amylin treatment. Amylin reduced the size of the first meal of the dark cycle when rats were pretreated with 4th-icv saline, yet amylin was ineffective after 4th-icv orexin-A pretreatment. Using double-label immunohistochemistry, we determined that some orexin-A fibers in the area postrema are located in proximity to amylin-responsive neurons. Therefore, hindbrain orexin-A may increase food intake, in part, by reducing the ability of rats to respond to amylin during a meal.

Maintenance on a high-fat diet impairs the anorexic response to glucagon-like-peptide-1 receptor activation

Previous data suggests that the adiposity signal leptin reduces food intake in part by enhancing sensitivity to short-term signals that promote meal termination, including glucagon-like peptide 1 (GLP-1). We hypothesized that maintenance on a high-fat (HF) diet, which causes resistance to leptin, would impair GLP-1's ability to reduce food intake. To test this hypothesis, we examined the anorexic responses to intraperitoneal injection of 100 μg/kg GLP-1 and 1 μg/kg exendin-4 (Ex-4), the potent, degradation resistant GLP-1 receptor agonist, in Wistar rats maintained on a low-fat (10%; LF) or HF (60%) diet for 4-6 weeks. Rats maintained on each of these diets were tested twice, once while consuming LF food and once while consuming HF food, to distinguish between effects of acute vs. chronic consumption of HF food. LF-maintained rats tested on LF diet reduced 60-min dark phase intake in response to GLP-1, but HF-maintained rats failed to respond to GLP-1 whether they were tested on HF or LF diet. LF-maintained rats tested on HF diet also showed no response, suggesting that even brief exposure to HF diet can impair sensitivity to GLP-1 receptor activation. Both LF- and HF-maintained rats showed significant anorexic responses to Ex4 at 4h post-treatment, but only LF-maintained rats had significantly reduced intake and body weight 24h after injections. To determine whether the ability of endogenous GLP-1 to promote satiation is impaired by HF maintenance, we examined the response to exendin 3 (9-39) (Ex9), a GLP-1 receptor antagonist. In LF-maintained rats, Ex9 increased intake significantly, but HF-maintained rats reduced food intake in response to Ex9. These data support the suggestion that maintenance on HF diet reduces the anorexic effects of GLP-1 receptor activation, and this phenomenon may contribute to overconsumption of high-fat foods.

The great imitator: miliary peritoneal tuberculosis mimicking stage III ovarian carcinoma

PURPOSE

To report a case of peritoneal tuberculosis initially mistaken at the time of surgery for metastatic ovarian carcinoma.

CASE REPORT

A 31-year-old Filipino female was found to have increasing abdominal pain, ascites, early satiety, increasing abdominal girth and bilateral complex masses. Diagnostic laparoscopy revealed the presence of > 4 liters of ascites, a frozen pelvis secondary to what appeared to be bilateral ovarian carcinomas, along with miliary seeding of the entire anterior abdominal wall, omentum, small bowel and small bowel mesentery, right and left diaphragmatic surfaces, and hepatic surface. Frozen section, at the time of laparotomy, revealed necrotizing granulomas most consistent with disseminated tuberculosis that was confirmed at the time of final pathologic review and culture.

CONCLUSION

Peritoneal tuberculosis can be mistaken for widely metastatic ovarian carcinoma at time of surgery.

A retrospective cohort study of falls in a psychiatric inpatient setting

Several factors increase the psychiatric inpatient's risk of falling, including side effects of medications and mental disorders that decrease awareness of environmental hazards. In this study, rates of falling were determined for a cohort of 4,156 psychiatric inpatients over 34 months. A total of 494 falls occurred among 376 patients. Thirty-five percent of the patients who fell required medical or nursing intervention. Forty-eight percent of the falls occurred in the over-60 age group. When other results were adjusted for age, neither gender nor diagnosis was found to increase the risk of falling, except for depressed patients under 20 years old, who were at less risk, and psychotic patients in their 60s, who were at greater risk. The authors discuss the costs of falls and preventive efforts instituted in their setting.

Contraband: the hidden risk

In a 28-month retrospective study of contraband possession in an inpatient psychiatric setting, 54 incidents of contraband confiscation were identified. Incidents were analyzed according to day and shift of occurrence, nature of contraband, patient diagnoses and characteristics, and patient outcome of contraband possession. Study findings stress the importance of clearly stated contraband policies and procedures, especially in light of patient and staff rights and responsibilities.

Global coordination of national public health strategies

Three periods can be distinguished in the brief history of global AIDS: silence, discovery and mobilization. The first period, starting in the mid-l970s, was the time of the “silent pandemic,” during which HIV spread — unnoticed—to at least five continents. During this period, when the virus was unrecognized, HIV could have — but did not — spread even more widely.

The description of AIDS in 1981 ended the silence and initiated the second period in the history of global AIDS — a period of discovery which culminated symbolically at the first International Conference on AIDS in June 1985 (Atlanta, USA). During this period, the modes of transmission were defined, the virus was discovered, and the capacity to detect anti-viral antibodies led to the discovery of large numbers of infected persons and to awareness of the long latency between infection and manifest disease.

AIDS--a global concern

HIV and AIDS are diseases which have rocked the health care agencies throughout the world in the 1980's. The editor of Midwifery has tried to secure a paper on the impact of AIDS on midwifery in some parts of the world. As much research has still to be done this paper is not available at the moment. The following paper was offered for publication and although written for nurses (it was presented at the 3rd International Intensive Care conference, Montreal Canada in August 1988) its message is for all health care workers.

Transmission of human immunodeficiency virus (HIV) in health-care settings worldwide

Based on the information available, transmission of human immunodeficiency virus (HIV) can and does occur in health-care settings. No cases of such transmission have been reported from an infected health-care worker to a patient. Transmission of HIV from an infected patient to a health-care worker has been documented after parenteral or mucous-membrane exposure to blood. However, this risk is less than 1%, is limited to exposure to blood, and can be further minimized through adherence to routine infection control measures. Patient-to-patient transmission through invasive equipment or through HIV-infected blood, blood products, organs, tissues, or semen also occurs but can be prevented by proper sterilization of instruments and through donor-deferral, donor screening, and heat treatment of Factors VIII or IX to inactivate the HIV. In health-care settings, prevention of HIV transmission requires education of all health-care workers and ancillary staff, provision of necessary equipment, and strict adherence to general infection control practices.

The global struggle against AIDS: WHO's strategy

AIDS (acquired immunodeficiency syndrome) knows no national boundaries. It has been reported from every part of the world. And the number of victims is growing. Today some 150,000 people are believed to be suffering from the disease. By 1991 one million new cases of AIDS could develop in people already infected with human immunodeficiency virus, or HIV--the virus that causes AIDS--predicts the WHO Special Programme on AIDS (SPA). Health care professionals, who have been on the main line of the fight against AIDS since it was first recognized in 1981, are now being joined by contingents of international groups, governments and top-level policymakers in a global attempt to stop its vicious spread. Attendance at conferences on the subject is testimony to this wide, united effort. Last year the Third International Conference on AIDS in Washington DC attracted a record-breaking 6,000 participants (researchers, health care workers and policymakers) from 50 countries (vs 2,800 the previous year) and this January health ministers and/or their colleagues from 148 countries (representing 95% of the world's population) attended the World Summit of Ministers of Health on Programmes for AIDS Prevention, organized by the British Health Ministry and WHO in London. On the following pages, INR provides nurses with an authoritative background on the new developments to the HIV epidemic, current preventive programmes and recommended policies. The first two articles are based on presentations given at ICN's Forum on AIDS at the Council of National Representatives meeting in New Zealand last August.(ABSTRACT TRUNCATED AT 250 WORDS)