Recent Advances in Neural Circuits for Taste Perception in Hunger.

Feeding is essential for survival and taste greatly influences our feeding behaviors. Palatable tastes such as sweet trigger feeding as a symbol of a calorie-rich diet containing sugar or proteins, while unpalatable tastes such as bitter terminate further consumption as a warning against ingestion of harmful substances. Therefore, taste is considered a criterion to distinguish whether food is edible. However, perception of taste is also modulated by physiological changes associated with internal states such as hunger or satiety. Empirically, during hunger state, humans find ordinary food more attractive and feel less aversion to food they usually dislike. Although functional magnetic resonance imaging studies performed in primates and in humans have indicated that some brain areas show state-dependent response to tastes, the mechanisms of how the brain senses tastes during different internal states are poorly understood. Recently, using newly developed molecular and genetic tools as well as in vivo imaging, researchers have identified many specific neuronal populations or neural circuits regulating feeding behaviors and taste perception process in the central nervous system. These studies could help us understand the interplay between homeostatic regulation of energy and taste perception to guide proper feeding behaviors.

Hypothalamic neuronal circuits regulating hunger-induced taste modification.

The gustatory system plays a critical role in sensing appetitive and aversive taste stimuli for evaluating food quality. Although taste preference is known to change depending on internal states such as hunger, a mechanistic insight remains unclear. Here, we examine the neuronal mechanisms regulating hunger-induced taste modification. Starved mice exhibit an increased preference for sweetness and tolerance for aversive taste. This hunger-induced taste modification is recapitulated by selective activation of orexigenic Agouti-related peptide (AgRP)-expressing neurons in the hypothalamus projecting to the lateral hypothalamus, but not to other regions. Glutamatergic, but not GABAergic, neurons in the lateral hypothalamus function as downstream neurons of AgRP neurons. Importantly, these neurons play a key role in modulating preferences for both appetitive and aversive tastes by using distinct pathways projecting to the lateral septum or the lateral habenula, respectively. Our results suggest that these hypothalamic circuits would be important for optimizing feeding behavior under fasting.

SatB2-Expressing Neurons in the Parabrachial Nucleus Encode Sweet Taste.

The gustatory system plays an important role in sensing appetitive and aversive tastes for evaluating food quality. In mice, taste signals are relayed by multiple brain regions, including the parabrachial nucleus (PBN) of the pons, before reaching the gustatory cortex via the gustatory thalamus. Recent studies show that taste information at the periphery is encoded in a labeled-line manner, such that each taste modality has its own receptors and neuronal pathway. In contrast, the molecular identity of gustatory neurons in the CNS remains unknown. Here, we show that SatB2-expressing neurons in the PBN play a pivotal role in sweet taste transduction. With cell ablation, in vivo calcium imaging, and optogenetics, we reveal that SatB2PBN neurons encode positive valance and selectively transmit sweet taste signals to the gustatory thalamus.

Affinity capillary electrophoresis for the assessment of binding affinity of carbohydrate-based cholera toxin inhibitors.

Developing tools for the study of protein carbohydrate interactions is an important goal in glycobiology. Cholera toxin inhibition is an interesting target in this context, as its inhibition may help to fight against cholera. For the study of novel ligands an affinity capillary electrophoresis (ACE) method was optimized and applied. The method uses unlabeled cholera toxin B-subunit (CTB) and unlabeled carbohydrate ligands based on ganglioside GM1-oligosaccharides (GM1os). In an optimized method at pH 4, adsorption of the protein to the capillary walls was prevented by a polybrene-dextran sulfate-polybrene coating. Different concentrations of the ligands were added to the BGE. CTB binding was observed by a mobility shift that could be used for dissociation constant (Kd ) determination. The Kd values of two GM1 derivatives differed by close to an order of magnitude (600 ± 20 nM and 90 ± 50 nM) which was in good agreement with the differences in their reported nanomolar IC50 values of an ELISA-type assay. Moreover, the selectivity of GM1os towards CTB was demonstrated using Influenza hemagglutinin (H5) as a binding competitor. The developed method can be an important platform for preclinical development of drugs targeting pathogen-induced secretory diarrhea.

Rationally Designed Chemically Modified Glycodendrimer Inhibits Streptococcus suis Adhesin SadP at Picomolar Concentrations.

Host cell surface carbohydrate receptors of bacterial adhesins are attractive targets in anti-adhesion therapy. The affinity of carbohydrate ligands with adhesins is usually found in the low µm range, which poses a problem for the design of effective inhibitors useful in therapy. In an attempt to increase the inhibitory power of carbohydrate ligands, we have combined the approach of chemical modification of ligands with their presentation as multivalent dendrimers in the design of an inhibitor of streptococcal adhesin SadP binding to its galactosyl-α1-4-galactose (galabiose) receptor. By using a phenylurea-modified galabiose-containing trisaccharide in a tetravalent dendrimeric scaffold, inhibition of adhesin at a low picomolar level was achieved. This study has resulted in one of the most potent inhibitors observed for bacterial adhesins and demonstrates a promising approach to develop anti-adhesives with the potential of practical applicability.

Efficacy and toxicity of pegylated liposomal doxorubicin-based chemotherapy in early-stage breast cancer: a multicenter retrospective case-control study.

AIM: PEGylated liposomal doxorubicin (PLD) has comparable efficacy and differing toxicity from conventional anthracyclines used to treat advanced breast cancer. This study compared disease-free survival and toxicity between PLD-based and conventional anthracycline-based regimens as adjuvant treatments for early-stage breast cancer. METHODS: We analyzed disease-free survival (DFS) rates, and adverse events in 102 women with early-stage (I-IIIa) breast cancer who received adjuvant PLD-based chemotherapy from 2002 to 2008. Each patient was matched for age, stage at diagnosis, HER-2 expression and hormone therapy use to a patient treated with an epirubicin-based regimen. Fisher's exact and Pearson's chi-square tests were used for categorical data analysis. Kaplan-Meier analysis and Cox regression models were used to analyze DFS. RESULTS: DFS at 5 years was 81.3% for PLD-based regimen and 82.3% for epirubicin-based regimen. This difference was not significant (p = 0.939). Stage IIIa disease was associated with a shorter DFS in univariate analysis (p = 0.048). In multivariate analysis that controlled for adjuvant treatment, age at diagnosis, stage, HER-2 expression, type of surgery and hormone and radiation therapy, stage IIIa disease (P = 0.023) and lack of hormone therapy (P = 0.024) were each independently associated with shorter DFS. Adverse events were evaluated, and with the exception of hand-foot syndrome, more grade 3 and 4 toxicities occurred in patients who received epirubicin-based regimens than in those given PLD-based regimens. CONCLUSION: For patients with early-stage breast cancer who received PLD-based adjuvant chemotherapy, 5-year DFS was comparable and toxicity was acceptable, yet different from those of patients who received epirubicin-based regimens.

Breast cancer-associated high-order SNP-SNP interaction of CXCL12/CXCR4-related genes by an improved multifactor dimensionality reduction (MDR-ER).

In association studies, the combined effects of single nucleotide polymorphism (SNP)-SNP interactions and the problem of imbalanced data between cases and controls are frequently ignored. In the present study, we used an improved multifactor dimensionality reduction (MDR) approach namely MDR-ER to detect the high order SNP­SNP interaction in an imbalanced breast cancer data set containing seven SNPs of chemokine CXCL12/CXCR4 pathway genes. Most individual SNPs were not significantly associated with breast cancer. After MDR­ER analysis, six significant SNP­SNP interaction models with seven genes (highest cross­validation consistency, 10; classification error rates, 41.3­21.0; and prediction error rates, 47.4­55.3) were identified. CD4 and VEGFA genes were associated in a 2­loci interaction model (classification error rate, 41.3; prediction error rate, 47.5; odds ratio (OR), 2.069; 95% bootstrap CI, 1.40­2.90; P=1.71E­04) and it also appeared in all the best 2­7­loci models. When the loci number increased, the classification error rates and P­values decreased. The powers in 2­7­loci in all models were >0.9. The minimum classification error rate of the MDR­ER­generated model was shown with the 7­loci interaction model (classification error rate, 21.0; OR=15.282; 95% bootstrap CI, 9.54­23.87; P=4.03E­31). In the epistasis network analysis, the overall effect with breast cancer susceptibility was identified and the SNP order of impact on breast cancer was identified as follows: CD4 = VEGFA > KITLG > CXCL12 > CCR7 = MMP2 > CXCR4. In conclusion, the MDR­ER can effectively and correctly identify the best SNP­SNP interaction models in an imbalanced data set for breast cancer cases.

Functional Characterization of Cholera Toxin Inhibitors Using Human Intestinal Organoids.

Preclinical drug testing in primary human cell models that recapitulate disease can significantly reduce animal experimentation and time-to-the-clinic. We used intestinal organoids to quantitatively study the potency of multivalent cholera toxin inhibitors. The method enabled the determination of IC50 values over a wide range of potencies (15 pM to 9 mM). The results indicate for the first time that an organoid-based swelling assay is a useful preclinical method to evaluate inhibitor potencies of drugs that target pathogen-derived toxins.

Gs-coupled GPCR signalling in AgRP neurons triggers sustained increase in food intake.

Agouti-related peptide (AgRP) neurons of the hypothalamus play a key role in regulating food intake and body weight, by releasing three different orexigenic molecules: AgRP; GABA; and neuropeptide Y. AgRP neurons express various G protein-coupled receptors (GPCRs) with different coupling properties, including Gs-linked GPCRs. At present, the potential role of Gs-coupled GPCRs in regulating the activity of AgRP neurons remains unknown. Here we show that the activation of Gs-coupled receptors expressed by AgRP neurons leads to a robust and sustained increase in food intake. We also provide detailed mechanistic data linking the stimulation of this class of receptors to the observed feeding phenotype. Moreover, we show that this pathway is clearly distinct from other GPCR signalling cascades that are operative in AgRP neurons. Our data suggest that drugs able to inhibit this signalling pathway may become useful for the treatment of obesity.

Functionalization of a Rigid Divalent Ligand for LecA, a Bacterial Adhesion Lectin.

The bacterial adhesion lectin LecA is an attractive target for interference with the infectivity of its producer P. aeruginosa. Divalent ligands with two terminal galactoside moieties connected by an alternating glucose-triazole spacer were previously shown to be very potent inhibitors. In this study, we chose to prepare a series of derivatives with various new substituents in the spacer in hopes of further enhancing the LecA inhibitory potency of the molecules. Based on the binding mode, modifications were made to the spacer to enable additional spacer-protein interactions. The introduction of positively charged, negatively charged, and also lipophilic functional groups was successful. The compounds were good LecA ligands, but no improved binding was seen, even though altered thermodynamic parameters were observed by isothermal titration calorimetry (ITC).

Tetra- versus Pentavalent Inhibitors of Cholera Toxin.

The five B-subunits (CTB5) of the Vibrio cholerae (cholera) toxin can bind to the intestinal cell surface so the entire AB5 toxin can enter the cell. Simultaneous binding can occur on more than one of the monosialotetrahexosylganglioside (GM1) units present on the cell surface. Such simultaneous binding arising from the toxins multivalency is believed to enhance its affinity. Thus, blocking the initial attachment of the toxin to the cell surface using inhibitors with GM1 subunits has the potential to stop the disease. Previously we showed that tetravalent GM1 molecules were sub-nanomolar inhibitors of CTB5. In this study, we synthesized a pentavalent version and compared the binding and potency of penta- and tetravalent cholera toxin inhibitors, based on the same scaffold, for the first time. The pentavalent geometry did not yield major benefits over the tetravalent species, but it was still a strong inhibitor, and no major steric clashes occurred when binding the toxin. Thus, systems which can adopt more geometries, such as those described here, can be equally potent, and this may possibly be due to their ability to form higher-order structures or simply due to more statistical options for binding.

Structural Insight into Multivalent Galactoside Binding to Pseudomonas aeruginosa Lectin LecA.

Multivalent galactosides inhibiting Pseudomonas aeruginosa biofilms may help control this problematic pathogen. To understand the binding mode of tetravalent glycopeptide dendrimer GalAG2 [(Gal-ß-OC6H4CO-Lys-Pro-Leu)4(Lys-Phe-Lys-Ile)2Lys-His-Ile-NH2] to its target lectin LecA, crystal structures of LecA complexes with divalent analog GalAG1 [(Gal-ß-OC6H4CO-Lys-Pro-Leu)2Lys-Phe-Lys-Ile-NH2] and related glucose-triazole linked bis-galactosides 3u3 [Gal-ß-O(CH2)n-(C2HN3)-4-Glc-ß-(C2HN3)-[ß-Glc-4-(N3HC2)]2-(CH2)n-O-ß-Gal (n = 1)] and 5u3 (n = 3) were obtained, revealing a chelate bound 3u3, cross-linked 5u3, and monovalently bound GalAG1. Nevertheless, a chelate bound model better explaining their strong LecA binding and the absence of lectin aggregation was obtained by modeling for all three ligands. A model of the chelate bound GalAG2·LecA complex was also obtained rationalizing its unusually tight LecA binding (KD = 2.5 nM) and aggregation by lectin cross-linking. The very weak biofilm inhibition with divalent LecA inhibitors suggests that lectin aggregation is necessary for biofilm inhibition by GalAG2, pointing to multivalent glycoclusters as a unique opportunity to control P. aeruginosa biofilms.

Differential responses of peripheral circadian clocks to a short-term feeding stimulus.

To investigate the effects of a short-term feeding stimulus on the expression of circadian genes in peripheral tissues, we examined the effects of a 30-min feeding stimulus on the rapid responses and circadian phases of five clock genes (Bmal1, Cry1, Per1, Per2 and Per3) and a clock-controlled gene (Dbp) in the heart and kidney of rats. A 30 min feeding stimulus was sufficient to alter the transcript levels and circadian phases of peripheral clock genes in a tissue-specific manner. The transcript levels of most clock genes (Bmal1, Cry1, Per1, and Per2) were significantly down-regulated in the heart within 2 h, which were affected marginally in the kidney (except Per1). In addition to the rapid response of clock gene expression, we found that the circadian phases of these clock genes were markedly shifted by the 30-min feeding stimulus in the heart within 1 day. However, the same feeding stimulus almost not affected the peak phases of these clock genes in the kidney. Moreover, these differential responses of peripheral clocks to the 30-min feeding were also similarly reflected in the expression of circadian output gene Dbp. Therefore, a 30-min feeding stimulus was sufficient to induce dyssynchronized peripheral circadian rhythm and might further result in disordered downstream physiological function in rats.

Comparison of clinical outcome of breast cancer patients with T1-2 tumor and one to three positive nodes with or without postmastectomy radiation therapy.

OBJECTIVE: The value of postmastectomy radiation therapy for breast cancer patients with T1-2 tumor and one to three positive nodes remains controversial. The purpose of this retrospective study was to compare the clinical outcomes of breast cancer patients with T1-2 and one to three positive nodes with and without postmastectomy radiation therapy. METHODS: Between May 1990 and June 2008, of 318 breast cancer patients with T1-2 and one to three positive nodes who had undergone modified radical mastectomy, 163 received postmastectomy radiation therapy and 155 did not. The clinico-pathologic characteristics were analyzed for clinical outcomes including loco-regional recurrence, distant metastasis, disease-free survival and overall survival. RESULTS: During the median follow-up period of 102 months, the clinical outcomes in postmastectomy radiation therapy versus no-postmastectomy radiation therapy groups were as follows: loco-regional recurrence rate (3.1 versus 11.0%, P= 0.006); distant metastasis rate (20.9 versus 27.7%, P= 0.152); 10-year disease-free survival rate (73.8 versus 61.3%, P= 0.001); and 10-year overall survival rate (82.1 versus 76.1%, P= 0.239). Through a multivariate analysis, a positive nodal ratio of ≥25% (hazard ratio= 4.571, P= 0.003) and positive lymphovascular invasion (hazard ratio= 2.738, P= 0.028) were found to be independent poor prognostic predictors of loco-regional recurrence. The reduction in loco-regional recurrence (hazard ratio= 0.208, P= 0.004) by postmastectomy radiation therapy was found to be significant. CONCLUSIONS: On the basis of our results, postmastectomy radiation therapy is highly recommended for breast cancer patients with T1-2 and one to three positive nodes, especially for high-risk subgroups with a positive nodal ratio of ≥25% and positive lymphovascular invasion, not only for reducing loco-regional recurrence but also for improving disease-free survival.

Enhanced effect of daytime restricted feeding on the circadian rhythm of streptozotocin-induced type 2 diabetic rats.

There is increasing awareness of the link between impaired circadian clocks and multiple metabolic diseases. However, the impairment of the circadian clock by type 2 diabetes has not been fully elucidated. To understand whether and how the function of circadian clock is impaired under the diabetic condition, we examined not only the expression of circadian genes in the heart and pineal gland but also the behavioral rhythm of type 2 diabetic and control rats in both the nighttime restricted feeding (NRF) and daytime restricted feeding (DRF) conditions. In the NRF condition, the circadian expression of clock genes in the heart and pineal gland was conserved in the diabetic rats, being similar to that in the control rats. DRF shifted the circadian phases of peripheral clock genes more efficiently in the diabetic rats than those in the control rats. Moreover, the activity rhythm of rats in the diabetic group was completely shifted from the dark phase to the light phase after 5 days of DRF treatment, whereas the activity rhythm of rats in the control group was still under the control of the suprachiasmatic nucleus (SCN) after the same DRF treatment. Furthermore, the serum glucose rhythm of type 2 diabetic rats was also shifted and controlled by the external feeding schedule, ignoring the SCN rhythm. Therefore, DRF shows stronger effect on the reentrainment of circadian rhythm in the type 2 diabetic rats, suggesting that the circadian system in diabetes is unstable and more easily shifted by feeding stimuli.

Cobalt chloride-induced hypoxia modulates the invasive potential and matrix metalloproteinases of primary and metastatic breast cancer cells.

BACKGROUND: Tumor hypoxia promotes cancer progression. Matrix metalloproteinases (MMPs) are required for breast cancer cell invasion. MATERIALS AND METHODS: The effect of cobalt chloride (CoCl(2))-stimulated hypoxia on invasion potential and the expression of MMPs and tissue inhibitors of metalloproteinases (TIMPs) were investigated in four breast cancer cell lines, derived from primary sites (HCC1395 and HCC1937) and metastatic sites (MCF-7 and MDA-MB-231). RESULTS: CoCl(2)-induced hypoxia induced HIF-1alpha protein expression in all four cell lines. Hypoxia significantly increased the invasiveness of HCC1395 cells, which did not correlate with a change of any one MMP. Constitutive MMP expression was different between primary and metastatic breast cancer cells. MMP-2 and MMP-9 measured by RT-PCR and zymography were notably expressed in primary cancer cells but not apparent in metastatic ones. MMP-7 was also highly expressed in primary cancer cells. Hypoxia increased the expression of MMP-1, -10 and -13 in metastatic breast cancer cells, whereas only MMP-13 was up-regulated in primary HCC1937 cells by hypoxic stimulation. TIMPs were not altered by hypoxia, except for TIMP-4 which was down-regulated in MDA-MB-231 cells. CONCLUSION: This study demonstrated a cell line-specific effect of hypoxia on invasive potential and differential expression of constitutive MMPs in primary versus metastatic breast cancer cells, i.e. primary cancer cells expressed a wider range of MMPs, in particular MMP-2, -7 and -9, than the metastatic ones. The data suggest that MMPs play no crucial roles in hypoxia-induced tumor progression in primary breast cancer cells.

Comparison of local recurrence and distant metastases between breast cancer patients after postmastectomy radiotherapy with and without immediate TRAM flap reconstruction.

BACKGROUND: The purpose of this study was to compare the local recurrence and distant metastasis of postmastectomy radiotherapy for breast cancer patients with and without immediate transverse rectus abdominis musculocutaneous (TRAM) flap reconstruction. METHODS: Between March of 1997 and October of 2001, 191 breast cancer patients received postmastectomy radiotherapy: 82 patients had TRAM flap reconstruction (TRAM flap group) and 109 patients did not (non-TRAM flap group). The mean radiation dose to the chest wall or entire TRAM flap, axillary area, and lower neck was 50 Gy (range, 48 to 54 Gy). The median follow-up period was 40 months. RESULTS: The percentages of chest wall recurrence were 3.7 percent (three of 82) in the TRAM flap group and 1.8 percent (two of 109) in the non-TRAM flap group (p = 0.653). The percentages of distant metastases were 12.2 percent (10 of 82) in the TRAM group and 15.6 percent (17 of 109) for the non-TRAM group (p = 0.67). The percentages of acute radiation dermatitis according to Radiation Therapy Oncology Group scoring criteria (TRAM flap group versus non-TRAM flap group) were as follows: grade I, 74 of 82 (90 percent) versus 93 of 109 (85 percent); grade II, seven of 82 (9 percent) versus 13 of 109 (12 percent); grade III, one of 82 (1 percent) versus three of 109 (3 percent) (p = 0.558). In the TRAM flap group, the increased percentage of fat necrosis was 8 percent. No flap loss was detected. CONCLUSIONS: There were no significant differences in the incidences of complication, locoregional recurrence, and distant metastasis between the TRAM flap and non-TRAM flap patients. The authors' results suggest that immediate TRAM flap reconstruction can be considered a feasible treatment for breast cancer patients requiring postmastectomy radiotherapy.

Serum adiponectin and leptin levels in Taiwanese breast cancer patients.

The role of two adipocytokines, adiponectin and leptin, in Taiwanese breast cancer patients remains to be determined. In this study, we analyzed the correlations between the serum levels of adiponectin and leptin and the various clinicopathological parameters in 100 newly diagnosed, histologically confirmed breast cancer patients and 100 controls. We found serum levels were decreased significantly for adiponectin in the breast cancer patients, in comparison to controls (Student t-test, P=0.003), while serum levels were increased significantly for leptin in the breast cancer patients in comparison to controls (Student t-test, P=0.025). Leptin/adiponectin (L/A ratio) were increased significantly in the breast cancer patients, in comparison to controls (Student t-test, P=0.009). Among the clinicopathological parameters, estrogen receptor, progesterone receptor, HER2/neu, lymph node metastasis, tumor stage, and tumor grade all showed no effect on the serum levels of adiponectin and leptin. BMI was negatively and positively correlated to serum adiponectin and leptin levels, respectively (Spearman's correlation, r=-0.333 and 0.323, respectively; P<0.001 for both). Intriguingly, serum L/A ratio disclosed a positive correlation to tumor size (r=0.21, P=0.036). In summary, our results suggest that low serum adiponectin levels and high serum leptin levels are associated with an increased risk for breast cancer. Also, independent of the effect of BMI, the increased serum ratio of L/A may indicate the presence of aggressive breast cancers.

Intra-abdominal desmoplastic small round cell tumor with elevated serum CA 125: a case report.

Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive tumor usually involving the peritoneum. It occurs more commonly in young males and is characterized by distinctive clinical, histologic, and immunophenotypic features. The histogenesis of DSRCT remains unknown. Coexpression of epithelial, mesenchymal, and neural antigens in the same cell provides evidence that DSRCT may arise from a primitive pluripotent stem cell with divergent differentiation. Recently, according to cytogenetic studies, some authors have proposed that the divergent differentiation of DSRCT may be the result of the fusion of Ewing's sarcoma gene and Wilms' tumor suppressor gene. Clinically, an elevated serum CA 125 concentration is found in some patients with DSRCT. We present the case of a 29-year-old man with diffuse intra-abdominal DSRCT and elevated serum CA 125 concentration and briefly review the relevant literature.