Impact of in-hospital medical management for COVID-19 pandemic on door-to-balloon time in patients with ST-elevation myocardial infarction

Background

Delayed door-to-balloon (DTB) time and deterioration of in-hospital mortality during the coronavirus disease 2019 (COVID-19) pandemic have been reported. Little is known about the impact of changes in in-hospital medical management before primary percutaneous coronary intervention (PCI) for COVID-19 such as screening test (antigen or polymerase chain reaction (PCR) tests, chest CT for excluding the pneumoniae) and primary PCI under full personal protective equipment (PPE) on DTB time and in-hospital mortality.

Purpose

The purpose of this study was to evaluate the impact of in-hospital medical management for COVID-19 on DTB time and in-hospital mortality during COVID-19 pandemic period.

Methods

We compared DTB time and in-hospital mortality of 502 ST-elevation myocardial infarction (STEMI) patients during COVID-19 pandemic (February 2020 and January 2021) with 2035 STEMI patients before pandemic (February 2016 and January 2020) using date from Mie ACS registry, a retrospective and multicenter registry.

Results

The COVID-19 screening tests before primary PCI and/or primary PCI under full PPE was performed on 173/502 (34.5%) patients (antigen or PCR tests; 39 (7.8%), chest CT; 156 (31.3%), full PPE; 11 (2.2%)). These patients had lower rate of achievement of DTB time ≤90 min compared with others (Figure 1A). Moreover, In-hospital management of COVID-19 screening tests and/or primary PCI under full PPE was an independent factor of DTB time>90 min with odds ratio of 1.94 (95% confidential interval: 1.37–2.76, p<0.001). In addition, in-hospital mortality of those patients was higher compared with others (Figure 1B).

Conclusion

In-hospital medical management for COVID-19 screening tests before primary PCI and/or primary PCI under full PPE was the independent factor of DTB time>90 min. This study reinforces the need to focus efforts on shortening DTB time, while controlling the epidemic of infection.

Funding Acknowledgement

Type of funding sources: None.

Comparing Structure-Function Relationships Based on Drasdo's and Sjöstrand's Retinal Ganglion Cell Displacement Models

Purpose

To compare structure-function relationships based on the Drasdo and Sjöstrand retinal ganglion cell displacement models.

Methods

Single eyes from 305 patients with glaucoma and 55 heathy participants were included in this multicenter, cross-sectional study. The ganglion cell and inner plexiform layer (GCIPL) thickness was measured using spectral domain optical coherence tomography. Visual field measurements were performed using the Humphrey 10-2 test. All A-scan pixels (128 × 512 pixels) were allocated to the closest 10-2 location with both displacement models using degree and millimeter scales. Structure-function relationships were investigated between GCIPL thickness and corresponding visual sensitivity in nonlong (160 eyes) and long (200 eyes) axial length (AL) groups.

Results

In both the nonlong and long AL groups, compared with the no-displacement model, both the Drasdo and the Sjöstrand models showed that the structure-function relationship around the fovea improved (P < 0.05). The magnitude of improvement in the area was either comparable between the model or was larger for the Drasdo model than the Sjöstrand model (P < 0.05). Meanwhile, structure-function relationships outside the innermost retinal region that were based on the Drasdo and Sjöstrand models were comparable to or were even worse than (in the case of the Drasdo model) those obtained using the no-displacement model.

Conclusions

Structure-function relationships evaluated based on both the Drasdo and Sjöstrand models significantly improved around the fovea, particularly when using the Drasdo model. This was not the case in other areas.

The role of endothelin B receptor in bone modelling during orthodontic tooth movement: a study on ETB knockout rats

The endothelin system has an important role in bone modelling during orthodontic tooth movement (OTM); however, little is known about the involvement of endothelin B receptors (ET_B) in this process. The aim of this study was to evaluate the role of ET_B in bone modelling during OTM using ET_B knockout rats (ET_B-KO). Thirty-two male rats were divided into 4 groups (n = 8 per group): the ET_B-KO appliance group, ET_B-KO control group, wild type (ET_B-WT) appliance group, and ET_B-WT control group. The appliance consisted of a super-elastic closed-coil spring placed between the first and second left maxillary molar and the incisors. Tooth movement was measured on days 0 and 35, and maxillary alveolar bone volume, osteoblast, and osteoclast volume were determined histomorphometrically on day 35 of OTM. Next, we determined the serum endothelin 1 (ET-1) level and gene expression levels of the osteoclast activity marker cathepsin K and osteoblast activity markers osteocalcin and dentin matrix acidic phosphoprotein 1 (DMP1) on day 35. The ET_B-KO appliance group showed significantly lower osteoblast activity, diminished alveolar bone volume and less OTM than the ET_B-WT appliance group. Our results showed that ET_B is involved in bone modelling in the late stage of OTM.

Investigating the structure-function relationship using Goldmann V standard automated perimetry where glaucomatous damage is advanced

PURPOSE

To investigate if the structure-function relationship between circumpapillary retinal nerve fibre layer (cpRNFL) thickness and visual field (VF) thresholds is stronger when using the Goldmann V target rather than the Goldman III target where glaucomatous damage is advanced.

METHODS

Optical coherence tomography (OCT) and VF (Humphrey Field Analyzer 24-2 or 30-2) measurements with Goldmann III (SITA standard) and V (full-threshold) targets were carried out in 51 eyes of 51 patients with primary open angle glaucoma. The relationship between cpRNFL thicknesses in supero- and infero-temporal sectors, and VF sensitivity with the Goldmann III or V target was investigated.

RESULT

Visual field sensitivities (dB) both with the Goldmann III target and Goldmann V target showed a floor effect in the structure-function relationship against cpRNFL thickness, at approximately 60 μm. There was no significant relationship between visual field sensitivity measured with the Goldmann V target (dB scale: p = 0.12, 1/Lambert scale: p = 0.40; linear mixed models) and cpRNFL thickness, when corresponding visual field sensitivity, measured with the Goldmann III target, was <20 dB.

CONCLUSION

There was no improvement in the structure-function relationship using the Goldmann V target (full-threshold), compared to using the Goldmann III target (SITA standard), where glaucomatous damage was advanced.

Relationship between novel intraocular pressure measurement from Corvis ST and central corneal thickness and corneal hysteresis

Aims

Corvis ST (CST) yields biomechanical corrected IOP (bIOP) which is purported to be less dependent on biomechanical properties. In our accompanied paper, it was suggested that the repeatability of bIOP is high. The purpose of the current study was to assess the relationship between intraocular pressure (IOP) measured with CST and central corneal thickness (CCT) and corneal hysteresis (CH), in comparison with IOP measured with Goldmann applanation tonometry (GAT) and the ocular response analyzer (ORA).

Methods

A total of 141 eyes from 141 subjects (35 healthy eyes and 106 glaucomatous eyes) underwent IOP measurements with GAT, CST and ORA. The relationships between IOP measurements (ORA-IOPg, ORA-IOPcc, CST-bIOP and GAT IOP) and biomechanical properties (CCT, CH and corneal resistance factor (CRF)) were analysed using the linear regression analysis.

Results

IOPg, IOPcc and GAT IOP were significantly associated with CCT (p<0.001), whereas bIOP was not significantly associated with CCT (p=0.19). IOPg, bIOP and GAT IOP were significantly associated with CH (IOPg: p<0.001; bIOP: p<0.001; GAT IOP: p=0.0054), whereas IOPcc was not significantly associated with CH (p=0.18). All of IOP records were associated with CRF (p<0.001).

Conclusion

The bIOP measurement from CST is independent from CCT, but dependent on CH and CRF.

Sustained effect of continuous treatment with bevacizumab following bevacizumab in combination with chemotherapy in a human ovarian clear cell carcinoma xenograft model

Although bevacizumab maintenance following bevacizumab in combination with chemotherapy has demonstrated significant prolongation of progression-free survival in clinical studies in patients with ovarian cancer, the majority of the cancer cases in the study were of the serous histotype; therefore, data regarding clear cell carcinoma is limited. Furthermore, the efficacy of bevacizumab beyond progression has not yet been demonstrated in ovarian cancer. A xenograft model using the human ovarian clear cell carcinoma cell line RMG-I was used to investigate the antitumor effects and the mechanisms of bevacizumab in maintenance treatment and bevacizumab when administered beyond disease progression. In the RMG-I model, bevacizumab maintenance following bevacizumab in combination with paclitaxel exhibited increased tumor suppression, compared with its absence, and inhibited the increase of microvessel density (MVD) in tumors. Following disease progression during bevacizumab maintenance, continued bevacizumab treatment in combination with PEGylated liposomal doxorubicin as a secondary chemotherapeutic agent had increased efficacy, compared with PEGylated liposomal doxorubicin alone, and resulted in lower MVD accompanied with lower levels of insulin-like growth factor binding protein-3, which is reported to have angiogenic activity. Continuous suppression of angiogenesis by bevacizumab may contribute to the superior efficacy of bevacizumab maintenance and bevacizumab beyond progression in ovarian cancer.

Repeatability of the Novel Intraocular Pressure Measurement From Corvis ST

Purpose

To assess the repeatability of intraocular pressure (IOP) measured with the Corvis ST (CST) and the Ocular Response Analyzer (ORA).

Methods

A total of 141 eyes from 141 subjects were studied, including 35 healthy eyes and 106 glaucomatous eyes. All subjects underwent IOP evaluations with Goldmann applanation tonometer, CST, and ORA. With CST, biomechanical corrected IOP (bIOP) was calculated; bIOP is purported to be less dependent on biomechanical properties. For ORA, corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated IOP (IOPg) were derived. The repeatability of the various IOP values was assessed using the coefficient of variance (CV) and the intraclass correlation coefficient (ICC).

Results

The CV with bIOP (5.5 ± 3.1: mean ± standard deviation) was significantly smaller than the CVs measured with IOPg (7.3 ± 4.3) and IOPcc (7.2 ± 4.4). ICC values were 0.90, 0.80, and 0.86 with IOPg, IOPcc, and bIOP, respectively.

Conclusions

The bIOP showed a better prevision and repeatability for IOP measurement.

Translational Relevance

The bIOP measurement from CST had a better reproducible than IOPcc measurement from ORA.

Mapping the Central 10° Visual Field to the Optic Nerve Head Using the Structure-Function Relationship

Purpose

To investigate the structure-function mapping in the central 10° by relating Humphrey field analyzer (HFA) 10-2 visual field (VF) and circumpapillary retinal nerve fiber layer (cpRNFL) thickness from spectral-domain optical coherence tomography (SD-OCT). We also compared the obtained results with a previously reported mapping between 10-2 VF and the optic disc.

Methods

In 151 eyes of 151 POAG patients and 35 eyes from 35 healthy participants, cpRNFL thickness measurements were obtained using SD-OCT and the 10-2 VF was measured with the HFA. The relationship between visual sensitivity and cpRNL thickness values in the temporal 180° was analyzed using least absolute shrinkage and selection operator (LASSO) regression. The optic disc angle corresponding to each VF test point was then derived using the coefficients from the optimal LASSO regression.

Results

The structure-function map obtained was largely consistent with the mapping reported previously; superior central VF test points correspond to a more vulnerable area of the optic disc, more distant toward the inferior pole from the center of the temporal quadrant (9:00 o'clock for the right eye) while inferior VF test points correspond closer to the center of the temporal quadrant. The prediction error tended to be large in the 'more vulnerable area' in the map reported previously.

Conclusions

The structure-function map obtained largely confirms the previously reported map; however, some important differences were observed.

Relationship between the Vertical Asymmetry of the Posterior Pole of the Eye and the Visual Field Damage in Glaucomatous Eyes

PURPOSE

This study investigated the relationship between the shape of the posterior pole of the eye and the vertical asymmetry of visual field (VF) damage in glaucomatous eyes.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 83 eyes of 43 patients with open-angle glaucoma.

METHODS

The VF was measured using the Humphrey 24-2 or 30-2 Swedish Interactive Thresholding Algorithm (SITA) standard. The vertical asymmetry of VF damage was defined as the difference between the mean total deviation (mTD) values of the superior and inferior hemi-retinas. This difference was calculated for the hemifield, central, middle, and peripheral areas. A vertical cross-sectional image of the macula was obtained, and the magnitudes of superior and inferior retinal tilt (RT) were calculated as the difference between the lower margins of the retinal pigment epithelium (RPE) at the fovea and at a location 2 mm superior or inferior to the RPE. The RT asymmetry was defined as the difference between the inferior and superior RT. Data were analyzed using a multivariate linear mixed model.

MAIN OUTCOME MEASURES

The relationship between mTD asymmetry (hemifield, central, middle, and peripheral) and both RT asymmetry and other factors (intraocular pressure, axial length, corneal radius, age, gender, mean deviation, refraction, and visual acuity) was assessed.

RESULTS

The inferior RT was significantly larger than the superior RT (P < 0.001). Hemifield mTD asymmetry was related to RT asymmetry (P = 0.017). These relationships were significant in the middle (P = 0.029) and peripheral areas (P = 0.023), but not in the central area (P = 0.40). Other factors were not related to mTD asymmetry.

CONCLUSIONS

Vertical asymmetry of the posterior pole was related to the vertical asymmetry of glaucomatous VF damage.

Comparison of Esterman disability scores obtained using Goldmann perimetry and the Humphrey field analyzer in Japanese low-vision patients

PURPOSE

To compare the Esterman Disability Score (EDS) obtained with Goldmann perimetry (GP) testing and the Humphrey field analyzer (HFA) in low vision Japanese subjects. Subjects were also divided into groups by diagnosis to examine how disease influences EDS measurements.

METHODS

The EDS was obtained using GP (GP-EDS) and the built-in testing program of the HFA (HFA-EDS). Tests were performed within 3 months of each other. Regression analyses were used to examine the relationship between GP-EDS and HFA-EDS.

RESULTS

A total of 128 visually impaired subjects were included in this study. Subjects had low vision because of glaucoma (57 subjects), age-related macular degeneration (AMD, 17 subjects), retinitis pigmentosa (RP, 17 subjects), and other causes (37 subjects). The GP-EDS obtained was well-correlated with HFA-EDS (r = 0.87, P < 0.001) and it was possible to estimate HFA-EDS from GP-EDS. The GP-EDS was significantly lower than the HFA-EDS in eyes with glaucoma and RP. There was no significant difference between EDS values in eyes with AMD or other disease.

CONCLUSION

The GP-EDS correlated well with the HFA-EDS. However, the relationship between the EDS measured with the two different testing modalities varies by disease.

Changes in Axial Length and Progression of Visual Field Damage in Glaucoma

Purpose

To investigate the relationship between axial length (AL) elongation and progression of primary open-angle glaucoma (POAG).

Methods

AL was measured twice over a 5.1 ± 0.76 (mean ± standard deviation: SD) year period in 125 eyes of 72 patients with POAG. The eyes were divided into not long (AL < 26 mm, 80 eyes) and long (>26 mm, 45 eyes) groups. During this period, patients' visual fields (VFs) were measured with the Humphrey Field Analyzer 12.4 ± 7.5 times and intraocular pressure (IOP) was measured with Goldmann applanation tonometry 27.0 ± 7.5 times. The relationship between the mean total deviation (mTD) progression rates in the whole field and superior and inferior hemifield, as well as in 10 VF sectors, and the variables of age, mean IOP, SD of IOP, AL, difference in AL (△AL), and mTD value at baseline was examined.

Results

There was a significant difference between AL at baseline and AL at repeat measurement (P < 0.0001). △AL was 0.035 ± 0.10 mm. An increase in △AL was significantly related to AL at baseline (P = 0.027), but not to age, mean IOP, and SD of IOP. △AL was related to the progression of mTD in the inferior hemifield (slower mTD progression was associated with increased △AL), but not in the whole field or superior hemifield. Increased △AL was related to slower progression rates in 2 of 10 sectors, both in the inferior hemifield.

Conclusions

The main finding was that an increase in AL was significantly related to slower VF progression in the inferior hemifield.

Investigating the Usefulness of Fundus Autofluorescence in Retinitis Pigmentosa

PURPOSE

To investigate the relationship between visual field (VF) loss and the rings of the ellipsoid zone (EZ) and autofluorescence (AF) in patients with retinitis pigmentosa (RP).

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 28 eyes of 15 patients with a clinical diagnosis of RP.

METHODS

The VF was measured at a 1-degree interval on the horizontal or vertical lines, within the central 10 degrees from fixation, using MP-3 microperimetry (Nidek Co. Ltd., Aichi, Japan), and the sensitivity deviation from the normative database was calculated. OCT was performed, and the EZ was identified. Fundus AF was also measured, and the AF ring was identified. The VF test points were categorized according to their relationship with the EZ line and AF ring. The relationship between mean retinal sensitivity deviations on both the horizontal and vertical lines and the diameters of the EZ line and the AF ring in the corresponding directions was analyzed. The relationship between visual sensitivity deviation and the locations against EZ line and AF rings was also investigated.

MAIN OUTCOME MEASURES

The relationship between the visual sensitivity deviation and the locations against EZ line and AF rings.

RESULTS

The diameter of the AF ring had a significantly stronger relationship with mean retinal sensitivity deviation compared with the diameter of the EZ line in both the horizontal and vertical directions. Test point location inside/on/outside the AF ring was significantly related to retinal sensitivity deviation independent of the location inside/outside the EZ line (P < 0.001, linear mixed model).

CONCLUSIONS

Visual sensitivity damage is significantly associated with the EZ lines and AF rings. The development of the AF ring is related to the decrease of visual function independent of and stronger than the EZ line.

Evaluating the Usefulness of MP-3 Microperimetry in Glaucoma Patients

PURPOSE

The purpose of the current study was to evaluate the test-retest reproducibility and structure-function relationship of the MP-3 microperimeter, compared against the Humphrey Field Analyzer (HFA).

METHODS

Design: Reliability and validity study.

SETTING

Institutional, or clinical practice.

STUDY POPULATION

Thirty eyes of 30 primary open-angle glaucoma patients were enrolled.

OBSERVATION PROCEDURES

Visual fields (VF) were measured twice with the MP-3 and HFA instruments, using the 10-2 test grid pattern in both perimeters. Ganglion cell complex (GCC) thickness was measured using optical coherence tomography (OCT). Test-retest reproducibility was assessed using the mean absolute deviation (MAD) measure at all 68 VF test points, and also the intraclass correlation coefficient (ICC) of the repeated VF sensitivities. The structure-function relationship between VF sensitivities (measured with MP-3 or HFA) and GCC thickness (adjusted for the retinal ganglion cell displacement) was analyzed using linear mixed modeling.

MAIN OUTCOME MEASURE

Reproducibility and structure-function relationship.

RESULTS

The average measurement duration with the HFA 10-2 was 7 minutes and 6 seconds (7m06s) ± 0m49s (mean ± standard deviation). A significantly (P < .001, paired Wilcoxon test) longer measurement duration was observed for the MP-3 test: 10m29s ± 2m55s. There were no significant differences in MAD and ICC values between HFA (MAD; 0.83 ± 0.69 dB and ICC: 0.89 ± 0.69, mean ± standard deviation) and MP-3 (MAD: 0.65 ± 0.67 dB and ICC: 0.89 ± 0.69). MP-3 VF sensitivities had a stronger structure-function relationship with GCC thickness compared to HFA.

CONCLUSIONS

The MP-3 microperimeter has a similar test-retest reproducibility to the HFA but a better structure-function relationship.

Preclinical study of antitumor activity of trastuzumab emtansine in HER2-positive biliary tract cancer

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Background: Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate composed of trastuzumab and DM1 (an anti-microtubule agent derived from maytansine) that is approved for the treatment of HER2-positive metastatic breast cancer. HER2-overexpression rate in biliary tract cancer (BTC) is reported as approximately 10%, and HER2-targeted therapy may enhance therapeutic efficacy in HER2-positive BTC. In this study, we investigated the antitumor activity of T-DM1 in several BTC cell lines and xenograft models. Methods: HER2 expression was detected by flow cytometry and Western blotting in 17 BTC cell lines. The cell growth inhibition activity of T-DM1 and DM1 was examined by quantifying the DNA with Hoechst 33258 nucleic acid stain. In vivo antitumor activity of T-DM1 was evaluated in three xenograft mouse models using cell lines with different levels of HER2 expression. HER2 expression in xenografts was assessed by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH), according to gastric cancer criteria. Cell cycle was assessed by flow cytometry after staining with propidium iodide. Apoptosis was assessed by caspase 3/7 activity measurement. Results: In the 17 BTC cell lines, HER2 expression was high in KMCH-1, Mz-ChA-1, and TGBC-18-TKB. Although cell growth inhibition of DM1 was similar in all cell lines (50% inhibitory concentration (IC50): 0.79–7.2 nM), that of T-DM1 was HER2-expression-dependent, with IC50 values in KMCH-1, Mz-ChA-1, and KKU-100 (which has low HER2 expression) of 0.031, 1.3, and 4.3 μg/mL, respectively. In KMCH-1 and Mz-ChA-1 xenograft models, T-DM1 treatment once every 3 weeks for 6 weeks showed significant dose-dependent antitumor activity, and tumor growth inhibition 21 days after first dose at 20 mg/kg T-DM1 was 108% (KMCH-1) and 75% (Mz-ChA-1), whereas there was no significant efficacy in KKU-100 xenograft model. Values for HER2 status (IHC score/FISH ratio of HER2 to CEP17) in KMCH-1, Mz-ChA-1, and KKU-100 tumor tissues were 3+/3.5, 2+/4.7, and 0/1.1, respectively. In KMCH-1, T-DM1 induced M phase arrest and apoptosis, as is reported in HER2-positive breast cancer cells. Conclusions: T-DM1 could be an effective therapy for HER2-overexpressed BTC.

Goldmann V Standard Automated Perimetry Underestimates Central Visual Sensitivity in Glaucomatous Eyes with Increased Axial Length

PURPOSE

To investigate the effect of axial length (AL) on the structure-function relationship between retinal nerve fiber layer (RNFL) thickness measurements and visual field (VF) sensitivity measured with Goldmann III and V.

METHOD

There were 85 eyes of 85 patients with primary open angle glaucoma included in the current study. Optical coherence tomography and VF (Humphrey Field Analyzer 24-2 or 30-2) measurements with Goldmann III and V targets were carried out in all patients. The optic disc and the VF were divided into six clusters and the relationship between circumpapillary RNFL (cpRNFL) thickness and VF sensitivity (with Goldmann III or V), age, and AL were investigated in each cluster.

RESULT

Visual sensitivity with Goldmann III (19.3 ± 11.7 dB, mean ± standard deviation) was significantly lower than that with Goldmann V (24.6 ± 11.0 dB, P < 0.001, linear mixed model). Visual sensitivities with both Goldmann III and V were significantly correlated with cpRNFL thickness in all clusters. Visual sensitivity decreased with increasing AL in the nasal retinal area for both targets, however, this phenomenon was only observed with the Goldmann V target in the temporal area.

CONCLUSION

Visual sensitivity measured with the size V target decreases with increasing AL in the temporal area, which corresponds to the papillomacular bundle. In the nasal retinal area, visual sensitivity decreases with the increase of AL for both Goldmann III and Goldmann V.

TRANSLATIONAL RELEVANCE

Careful consideration is needed when measuring visual sensitivity using Goldmann V target in glaucomatous eyes with increased AL.

Bevacizumab counteracts VEGF-dependent resistance to erlotinib in an EGFR-mutated NSCLC xenograft model

Erlotinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), shows superior efficacy in patients with non-small cell lung cancer (NSCLC) harboring activating EGFR mutations (EGFR Mut⁺). However, almost all tumors eventually develop resistance to erlotinib. Recently, the Phase II JO25567 study reported significant prolongation of progression-free survival (PFS) by erlotinib plus bevacizumab combination compared with erlotinib in EGFR Mut⁺ NSCLC. Herein, we established a preclinical model which became refractory to erlotinib after long-term administration and elucidated the mode of action of this combination. In this model, tumor regrowth occurred after remarkable shrinkage by erlotinib; regrowth was successfully inhibited by erlotinib plus bevacizumab. Tumor vascular endothelial growth factor (VEGF) was greatly reduced by erlotinib in the erlotinib-sensitive phase but significantly increased in the erlotinib-refractory phase despite continued treatment with erlotinib. Although EGFR phosphorylation remained suppressed in the erlotinib-refractory phase, phosphorylated extracellular signal-regulated kinase (pERK), phosphorylated AKT, and phosphorylated signal transducer and activator of transcription 3 (pSTAT3) were markedly higher than in the erlotinib-sensitive phase; among these, pERK was suppressed by erlotinib plus bevacizumab. MVD was decreased significantly more with erlotinib plus bevacizumab than with each drug alone. In conclusion, the erlotinib plus bevacizumab combination demonstrated promising efficacy in the B901L xenograft model of EGFR Mut⁺ NSCLC. Re-induction of VEGF and subsequent direct or indirect VEGF-dependent tumor growth was suggested as a major mechanism of erlotinib resistance, and erlotinib plus bevacizumab achieved remarkably prolonged antitumor activity in this model.

The Relationship between Corvis ST Tonometry and Ocular Response Analyzer Measurements in Eyes with Glaucoma

It is important to compare the results of Corneal Visualization Scheimpflug Technology instrument (CST) measurements and Reichert Ocular Response Analyzer (ORA) parameters. The purpose of the study was to investigate the association between CST measurements and ORA parameters in ninety-five patients with primary open-angle glaucoma. Measurements of CST, ORA, axial length (AL), average corneal curvature (CC), central corneal thickness (CCT) and intraocular pressure (IOP) with Goldmann applanation tonometry (GAT) were carried out. The association between CST and ORA parameters was assessed using linear regression analysis, with model selection based on the second order bias corrected Akaike Information Criterion index. Measurements from ORA (corneal hysteresis [CH] and corneal response factor [CRF]) had high intraclass correlation coefficients (ICC) and low coefficients of variation, but some CST parameters showed much lower reproducibility, namely: A1 length, A2 length, highest concavity time and peak distance. Of 12 CST parameters tested, 8 were significantly correlated with CH and 10 were significantly correlated with CRF, however, the magnitude of the correlation coefficients were weak to moderate at best. The optimal model to explain CH using CST measurements was given by: CH = -76.3 + 4.6*A1 time + 1.9*A2 time + 3.1 * highest concavity deformation amplitude + 0.016*CCT (R² = 0.67, p <0.001). Similarly, the optimal model for CRF was given by: CRF = -53.5 + 4.2*A1 time + 1.9*A1 length + 20.8*A1 deformation amplitude + 0.8*A2 time + 0.017*CCT (R² = 0.73, p <0.001). ORA parameters show higher reproducibility than CST measurements. Although many CST parameters are significantly related to ORA parameters, the strengths of these relationships are weak to moderate.

Impact of bevacizumab in combination with erlotinib on EGFR-mutated non-small cell lung cancer xenograft models with T790M mutation or MET amplification

Erlotinib (ERL), an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, shows notable efficacy against non-small cell lung cancer (NSCLC) harboring EGFR mutations. Bevacizumab (BEV), a humanized monoclonal antibody to vascular endothelial cell growth factor (VEGF), in combination with ERL (BEV+ERL) significantly extended progression-free survival in patients with EGFR-mutated NSCLC compared with ERL alone. However, the efficacy of BEV+ERL against EGFR-mutated NSCLC harboring T790M mutation or MET amplification, is unclear. Here, we examined the antitumor activity of BEV+ERL in four xenograft models of EGFR-mutated NSCLC (three harboring ERL resistance mutations). In the HCC827 models (exon 19 deletion: DEL), ERL significantly inhibited tumor growth by blocking EGFR signal transduction. Although there was no difference between ERL and BEV+ERL in maximum tumor growth inhibition, BEV+ERL significantly suppressed tumor regrowth during a drug-cessation period. In the HCC827-EPR model (DEL+T790M) and HCC827-vTR model (DEL+MET amplification), ERL reduced EGFR signal transduction and showed less pronounced but still significant tumor growth inhibition than in the HCC827 model. In these models, tumor growth inhibition was significantly stronger with BEV+ERL than with each single agent. In the NCI-H1975 model (L858R+T790M), ERL did not inhibit growth or EGFR signal transduction, and BEV+ERL did not inhibit growth more than BEV. BEV alone significantly decreased microvessel density in each tumor. In conclusion, addition of BEV to ERL did not enhance antitumor activity in primarily ERL-resistant tumors with T790M mutation; however, BEV+ERL enhanced antitumor activity in T790M mutation- or MET amplification-positive tumors as long as their growth remained significantly suppressed by ERL.

Abstract 2691: Role of trastuzumab in the combination treatment for a HER2-positive trastuzumab-resistant gastric cancer xenograft model

Objective: Trastuzumab (Tras) resistance is an important clinical problem to be resolved for HER2-positive gastric cancers (GC). Even after the tumor develops resistance to Tras, continuous anti-HER2 therapies, including Tras with chemotherapy (Tras beyond PD) or trastuzumab emtansine (T-DM1), could be effective treatment options. The Tras-sensitive cell line GLM-1 was established from a liver metastasis of a GC patient (Nakanishi et al. 2005), and the Tras-resistant cell line GLM1-HerR2 (R2) was established from GLM-1 by in vivo selection (Oshima et al. 2014). In this study, we used GLM1 and R2 xenograft models to examine the Tras-resistant mechanism of R2 and the effects of Tras plus paclitaxel (PTX) or T-DM1.

Methods: BALB/c-nu/nu mice subcutaneously inoculated with GLM1 or R2 received Tras (40 mg/kg, qw) intraperitoneally, PTX (15 mg/kg, qw) or T-DM1 (10-40 mg/kg, q3w) intravenously (Day 1). Tumor volume (TV) was measured to evaluate antitumor effects, HercepTest® was used for HER2 status, and flow cytometry to analyze Tras-binding ability. Cell proliferation after knockdown of HER family receptors was measured by BrdU incorporation. Signal transduction was examined by Western blot for tumors excised on Days 2 and 5.

Results: In contrast to GLM-1, R2 showed resistance to Tras treatment in xenograft experiments. There were no clear differences in HER2 score (3+), Tras-binding ability, p-HER2, p-HER3, p-AKT levels, or PIK3CA status (no hot spot mutation). Effects of gene knockdown of EGFR/HER2/HER3 in GLM-1 and R2 on cell proliferation were similar (ca. 10%/50%-60%/10% reduction, respectively). In GLM-1 tumors, Tras treatment decreased p-AKT, increased p27 protein, and decreased p-Rb, resulting in G1 cell cycle arrest, whereas in the R2 tumors changes in those molecules were few. These results suggest that escape from Tras-induced G1 arrest could be a resistant mechanism of R2. Based on the above results, and because in R2 cells HER2 remained a driver of proliferation and mitotic arrest was maintained, we hypothesized that Tras + PTX would show a higher antitumor effect than PTX alone. In the R2 xenograft model on Day 22, the Tras + PTX group showed a significantly higher antitumor activity (TV: 2 ± 3 mm3) than the PTX alone group (TV: 208 ± 209 mm3). In tumor specimens from the PTX and Tras + PTX groups, p-histon H3 (an M phase marker) was increased on Day 2. However, the Tras + PTX group, unlike the PTX group, showed markedly decreased p-histon H3 on Day 5, which suggests that Tras in combination with PTX enhances apoptosis in R2 tumors. Interestingly, T-DM1 showed dose-dependent antitumor activity in both GLM-1 and R2 xenografts.

Conclusion: It was indicated that continuous anti-HER2 treatment, including Tras with chemotherapy or T-DM1 monotherapy, could be efficacious treatments for HER2-positive Tras-resistant GC tumors that emerge during previous Tras treatment.

Citation Format: Sei Shu, Yoriko Yamashita-Kashima, Mieko Yanagisawa, Yoichiro Moriya, Naoki Harada. Role of trastuzumab in the combination treatment for a HER2-positive trastuzumab-resistant gastric cancer xenograft model. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2691. doi:10.1158/1538-7445.AM2015-2691

Superior antitumor activity of trastuzumab combined with capecitabine plus oxaliplatin in a human epidermal growth factor receptor 2-positive human gastric cancer xenograft model

In the treatment of human epidermal growth factor receptor 2 (HER2)-positive advanced gastric or gastroesophageal junction cancer, it has been reported that the combination of trastuzumab with capecitabine plus cisplatin, or with 5-fluorouracil (5-FU) plus cisplatin, significantly increased overall survival compared with chemotherapy alone (ToGA trial). In addition, adjuvant therapy with capecitabine plus oxaliplatin (XELOX) improved the survival of patients who received curative D2 gastrectomy (CLASSIC trial). However, the efficacy of the combination of trastuzumab with XELOX for patients with HER2-positive gastric cancer remains unknown. The aim of this study, was to investigate the efficacy of the combination of trastuzumab with XELOX in a HER2-positive human gastric cancer xenograft model. Combination treatment with these three agents (trastuzumab 20 mg/kg, capecitabine 359 mg/kg and oxaliplatin 10 mg/kg), was found to exhibit a significantly stronger antitumor activity in NCI-N87 xenografts compared with either trastuzumab or XELOX alone. In this model, treatment with trastuzumab alone or trastuzumab plus oxaliplatin enhanced the expression of thymidine phosphorylase (TP), a key enzyme in the generation of 5-FU from capecitabine in tumor tissues. In in vitro experiments, trastuzumab induced TP mRNA expression in NCI-N87 cells. In addition, NCI-N87 cells co-cultured with the natural killer (NK) cell line CD16(158V)/NK-92 exhibited increased expression of TP mRNA. When NCI-N87 cells were cultured with CD16(158V)/NK-92 cells in the presence of trastuzumab, the mRNA expression of cytokines reported to have the ability to induce TP was upregulated in tumor cells. Furthermore, a medium conditioned by CD16(158V)/NK-92 cells also upregulated the expression of TP mRNA in NCI-N87 cells. These results suggest that trastuzumab promotes TP expression, either by acting directly on NCI-N87 cells, or indirectly via a mechanism that includes trastuzumab-mediated interactions between NK and NCI-N87 cells. Therefore, the combination of trastuzumab with XELOX may be a potent therapy for HER2-positive gastric cancer.

Uremic serum contains humoral factor(s) larger than fifty kilodaltons which suppresses endothelin production in cultured endothelial cells

Direct effects of human uremic serum on the production of endothelin-1 in cultured porcine endothelial cells were examined in this study. Uremic serum decreased the level of monomeric endothelin-1 secreted into the culture medium by endothelial cells. This effect occurred at a transcriptional step because uremic serum decreased the endothelin-1 mRNA level in those cells. For the partial characterization of this inhibitory activity, uremic serum was fractionated with a centricut column. Uremic serum contains humoral factor(s) larger than 50 kD which suppress the endothelin-1 mRNA level in cultured endothelial cells.

Antitumor activities of bevacizumab for KRAS, BRAF, and PIK3CA mutated human colorectal cancer xenograft models

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Background: In colorectal cancer, it has been reported that mutations (mts) in KRAS, BRAF, or PIK3CA can have a negative impact on molecular target therapies. Especially, a KRAS mt represents a predictive biomarker for resistance to anti-EGFR antibodies. Bevacizumab (BV), an anti-VEGF-A antibody, has been demonstrated to have clinical benefits in colorectal cancers; however, the impact of mts in especially BRAF or PIK3CA on the efficacy of BV remains unknown. In this study, we examined the antitumor activity of BV in human colorectal cancer xenograft models harboring these mts. Methods: BALB-nu/nu mice were subcutaneously inoculated with 15 colorectal cancer cell lines. BV was intraperitoneally administered every week for 3 weeks at a dose of 5 mg/kg. Antitumor activity was evaluated by determining tumor volume and tumor growth inhibition (TGI) on day 22. The colorectal cancer cell lines used were screened for KRAS, BRAF, and PIK3CA mts by direct sequencing of hot spots. Statistical analysis was performed using Wilcoxon test for tumor volume and TGI and Fisher's exact test for the correlation of genotype and antitumor effect. Results: Genotypes of KRAS, BRAF, and PIK3CA were all wild-type (wt) in COLO320DM, KM-12 and SW48 and in other cell lines were, respectively, as follows: COLO205, HT-29, WiDr and LS411N: wt, mt, and wt; SW620 and LoVo: mt, wt, and wt; HCT-8, HCT116, DLD-1, T84 and LS174T: mt, wt, and mt; RKO: wt, mt and mt. BV as a non-responder (NR) showed no significant antitumor activity in 3 cell lines (WiDr, LoVo and DLD-1), whereas as a responder (R) significant activity was observed in the other 12 cell lines. There was no significant difference in the antitumor effect of BV between cell lines depending on KRAS, BRAF or PIK3CAmutational status in terms of TGI and R/NR ratio (Table). Conclusions: BV shows antitumor effect regardless of mutational status of KRAS, BRAF, or PIK3CA in colorectal cancers. [Table: see text]

Predictive markers of capecitabine sensitivity identified from the expression profile of pyrimidine nucleoside-metabolizing enzymes

Molecular markers predicting sensitivity to anticancer drugs are important and useful not only for selecting potential responders but also for developing new combinations. In the present study, we analyzed the difference in the sensitivity of xenograft models to capecitabine (Xeloda®), 5'-deoxy-5-fluorouridine (5'-DFUR, doxifluridine, Furtulon®) and 5-FU by comparing the mRNA levels of 12 pyrimidine nucleoside-metabolizing enzymes. Amounts of mRNA in the tumor tissues of 80 xenograft models were determined by real-time RT-PCR and mutual correlations were examined. A clustering analysis revealed that the 12 enzymes were divided into two groups; one group consisted of 8 enzymes, including orotate phosphoribosyl transferase (OPRT), TMP kinase (TMPK) and UMP kinase (UMPK), and was related to the de novo synthesis pathway for nucleotides, with mRNA expression levels showing significant mutual correlation. In the other group, 4 enzymes, including thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD), were involved in the salvage/degradation pathway of the nucleotides, and the mRNA levels of this group were dispersed more widely than that of the de novo group. Antitumor activity was assessed in 24 xenograft models for each drug. The antitumor activity of capecitabine and 5'-DFUR correlated significantly with the mRNA levels of TP and with the TP/DPD ratio, whereas the activity of 5-FU correlated significantly with OPRT, TMPK, UMPK and CD. In a stepwise regression analysis, TP and DPD were found to be independent predictive factors of sensitivity to capecitabine and 5'-DFUR, and UMPK was predictive of sensitivity to 5-FU. These results indicate that the predictive factors for sensitivity to capecitabine and 5'-DFUR in xenograft models may be different from those for 5-FU, suggesting that these drugs may have different responders in clinical usage.

Relationship between vision-related quality of life and different types of existing visual fields in Japanese patients

To investigate the vision-related quality of life (VRQOL) in relation to the type of existing visual field (EVF) in the presence of visual field defect. We evaluated the VRQOL of 95 patients by using Visual Function Questionnaire-25 (NEI VFQ-25). Patients fulfilled the following criteria: (1) they underwent a Goldmann perimetry (GP) test within 3 months of the initial visit, (2) the results of the GP test could be classified into three categories, and (3) the best-corrected decimal visual acuity (VA) was ≤0.3. The EVF was assessed by composite measurement of both eyes for the V-4e or I-4e isopters, as obtained using the GP test. We compared the VFQ-25 scores between three groups: (1) the "center and peripheral" group in which the EVF of the V-4e area was >30º and the I-4e area was <30º, (2) the "central VF" group in which the EVF of the V-4e area was <20º, and (3) the "central VF loss" group in which the central scotoma was >5º and the EVF of the V-4e area was >30º in peripheral vision. There were significant differences between the three groups (P = 0.02, ANOVA). The total score of the "central VF loss" group was significantly lower than those of the "center and peripheral" and "central VF" groups. The central vision influenced the VRQOL to a greater extent than peripheral vision.

Biomarkers for antitumor activity of bevacizumab in gastric cancer models

Background

Bevacizumab is a humanized monoclonal antibody to human vascular endothelial cell growth factor (VEGF) and has been used for many types of cancers such as colorectal cancer, non-small cell lung cancer, breast cancer, and glioblastoma. Bevacizumab might be effective against gastric cancer, because VEGF has been reported to be involved in the development of gastric cancer as well as other cancers. On the other hand, there are no established biomarkers to predict the bevacizumab efficacy in spite of clinical needs. Therefore, we tried to identify the predictive markers for efficacy of bevacizumab in gastric cancer patients by using bevacizumab-sensitive and insensitive tumor models.

Methods

Nine human gastric and two colorectal cancer mouse xenografts were examined for their sensitivity to bevacizumab. We examined expression levels of angiogenic factors by ELISA, bioactivity of VEGF by phosphorylation of VEGFR2 in HUVEC after addition of tumor homogenate, tumor microvessel density by CD31-immunostaining, and polymorphisms of the VEGF gene by HybriProbe™ assay.

Results

Of the 9 human gastric cancer xenograft models used, GXF97, MKN-45, MKN-28, 4-1ST, SC-08-JCK, and SC-09-JCK were bevacizumab-sensitive, whereas SCH, SC-10-JCK, and NCI-N87 were insensitive. The sensitivity of the gastric cancer model to bevacizumab was not related to histological type or HER2 status. All tumors with high levels of VEGF were bevacizumab-sensitive except for one, SC-10-JCK, which had high levels of VEGF. The reason for the refractoriness was non-bioactivity on the phosphorylation of VEGFR2 and micro-vessel formation of VEGF, but was not explained by the VEGF allele or VEGF165b. We also examined the expression levels of other angiogenic factors in the 11 gastrointestinal tumor tissues. In the refractory models including SC-10-JCK, tumor levels of another angiogenic factor, bFGF, were relatively high. The VEGF/bFGF ratio correlated more closely with sensitivity to bevacizumab than with the VEGF level.

Conclusions

VEGF levels and VEGF/bFGF ratios in tumors were related to bevacizumab sensitivity of the xenografts tested. Further clinical investigation into useful predictive markers for bevacizumab sensitivity is warranted.

Animals lacking endothelin-converting enzyme-2 are deficient in learning and memory

Endothelin-converting enzyme (ECE)-2 is a metalloprotease that possesses many properties consistent with it being a neuropeptide-processing enzyme. This protease is found primarily in neural tissues, with high levels of expression in midbrain, cerebellum, hypothalamus, frontal cortex and spinal cord and moderate levels in hippocampus and striatum. To evaluate its role in neural function, mice have been generated lacking this enzyme. Physical appearance, autonomic reflexes, motor co-ordination, balance, locomotor activity and spontaneous emotional responses appear normal in these knockout (KO) mice. However, these mutants display deficits in learning and memory as evidenced by marked impairment in the Morris water maze. Knockout mice are also deficient in object recognition memory where they show delays in discerning changes in object location and in recognizing the introduction of a novel object. In this study, perseveration appears to interfere with learning and memory. Finally, mutants are impaired in social transmission of food preference where they show poor short-term memory and perturbations in long-term memory; the latter can be ameliorated by reminder cues. As ECE-2 has been implicated in Alzheimer's disease, the deficits in learning and memory in the KO mice may provide unique insights into processes that may contribute to this disease and possible other disorders of cognition.

Erlotinib inhibits osteolytic bone invasion of human non-small-cell lung cancer cell line NCI-H292

Previous preclinical and clinical findings have suggested a potential role of epidermal growth factor receptor (EGFR) in osteoclast differentiation and the pathogenesis of bone metastasis in cancer. In this study, we investigated the effect of erlotinib, an orally active EGFR tyrosine kinase inhibitor (TKI), on the bone invasion of human non-small-cell lung cancer (NSCLC) cell line NCI-H292. First, we established a novel osteolytic bone invasion model of NCI-H292 cells which was made by inoculating cancer cells into the tibia of scid mice. In this model, NCI-H292 cells markedly activated osteoclasts in tibia, which resulted in osteolytic bone destruction. Erlotinib treatment suppressed osteoclast activation to the basal level through suppressing receptor activator of NF-κB ligand (RANKL) expression in osteoblast/stromal cell at the bone metastatic sites, which leads to inhibition of osteolytic bone destruction caused by NCI-H292 cells. Erlotinib inhibited the proliferation of NCI-H292 cells in in vitro. Erlotinib suppressed the production of osteolytic factors, such as parathyroid hormone-related protein (PTHrP), IL-8, IL-11 and vascular endothelial growth factor (VEGF) in NCI-H292 cells. Furthermore, erlotinib also inhibited osteoblast/stromal cell proliferation in vitro and the development of osteoclasts induced by RANKL in vitro. In conclusion, erlotinib inhibits tumor-induced osteolytic invasion in bone metastasis by suppressing osteoclast activation through inhibiting tumor growth at the bone metastatic sites, osteolytic factor production in tumor cells, osteoblast/stromal cell proliferation and osteoclast differentiation from mouse bone marrow cells.

Association between changes in visual acuity and vision-related quality of life in Japanese patients with low vision

PURPOSE

To investigate the association between vision-related quality of life (VRQOL) and changes in visual acuity (VA).

METHODS

We examined the VA in 100 patients for > 1 year and evaluated the degree of its impact on VRQOL using the National Eye Institute Visual Function (VF) Questionnaire (VFQ-25; Japanese version). Before determining VFQ-25, we monitored the changes in VA in these patients for 1 year and classified them into the following two groups depending on VA changes. Patients exhibiting a decline of > 3 steps in VA, as assessed by the logarithm of the minimum angle of resolution scale, were placed in the 'decline' group (47.0%) and patients exhibiting no change in VA were placed in the 'no change' group (53.0%). We compared the VFQ-25 scores between both groups in all patients with glaucoma (GLA) and macular degeneration (MD).

RESULTS

The total score of the decline was 34.9 ± 13.6 and that of the no change group was 44.6 ± 13.9: the difference in the scores between both groups was statistically significant (p = 0.006). Similar results were obtained for patients with GLA and MD (p = 0.007 and 0.003, respectively).

CONCLUSION

VRQOL differed between patients with constant VA and those with reduced VA, even though VA values were equal at a certain time point.

Narcoleptic orexin receptor knockout mice express enhanced cholinergic properties in laterodorsal tegmental neurons

Pharmacological studies of narcoleptic canines indicate that exaggerated pontine cholinergic transmission promotes cataplexy. As disruption of orexin (hypocretin) signaling is a primary defect in narcolepsy with cataplexy, we investigated whether markers of cholinergic synaptic transmission might be altered in mice constitutively lacking orexin receptors (double receptor knockout; DKO). mRNA for Choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT) and the high-affinity choline transporter (CHT1) but not acetylcholinesterase (AChE) was significantly higher in samples from DKO than wild-type (WT) mice. This was region-specific; levels were elevated in samples from the laterodorsal tegmental nucleus (LDT) and the fifth motor nucleus (Mo5) but not in whole brainstem samples. Consistent with region-specific changes, we were unable to detect significant differences in Western blots for ChAT and CHT1 in isolates from brainstem, thalamus and cortex or in ChAT enzymatic activity in the pons. However, using ChAT immunocytochemistry, we found that while the number of cholinergic neurons in the LDT and Mo5 were not different, the intensity of somatic ChAT immunostaining was significantly greater in the LDT, but not Mo5, from DKO than from WT mice. We also found that ChAT activity was significantly reduced in cortical samples from DKO compared with WT mice. Collectively, these findings suggest that the orexins can regulate neurotransmitter expression and that the constitutive absence of orexin signaling results in an up-regulation of the machinery necessary for cholinergic neurotransmission in a mesopontine population of neurons that have been associated with both normal rapid eye movement sleep and cataplexy.

Histamine-1 receptor is not required as a downstream effector of orexin-2 receptor in maintenance of basal sleep/wake states

AIM

The effect of orexin on wakefulness has been suggested to be largely mediated by activation of histaminergic neurones in the tuberomammillary nucleus (TMN) via orexin receptor-2 (OX(2)R). However, orexin receptors in other regions of the brain might also play important roles in maintenance of wakefulness. To dissect the role of the histaminergic system as a downstream mediator of the orexin system in the regulation of sleep/wake states without compensation by the orexin receptor-1 (OX(1)R) mediated pathways, we analysed the phenotype of Histamine-1 receptor (H(1)R) and OX(1)R double-deficient (H(1)R(-/-);OX(1)R(-/-)) mice. These mice lack OX(1)R-mediated pathways in addition to deficiency of H(1)R, which is thought to be the most important system in downstream of OX(2)R.

METHODS

We used H(1)R deficient (H(1)R(-/-)) mice, H(1)R(-/-);OX(1)R(-/-) mice, OX(1)R and OX(2)R double-deficient (OX(1)R(-/-);OX(2)R(-/-)) mice, and wild type controls. Rapid eye movement (REM) sleep, non-REM (NREM) sleep and awake states were determined by polygraphic electroencephalographic/electromyographic recording.

RESULTS

No abnormality in sleep/wake states was observed in H(1)R(-/-) mice, consistent with previous studies. H(1)R(-/-);OX(1)R(-/-) mice also showed a sleep/wake phenotype comparable to that of wild type mice, while OX(1)R(-/-); OX(2)R(-/-) mice showed severe fragmentation of sleep/wake states.

CONCLUSION

Our observations showed that regulation of the sleep/wake states is completely achieved by OX(2)R-expressing neurones without involving H(1)R-mediated pathways. The maintenance of basal physiological sleep/wake states is fully achieved without both H(1) and OX(1) receptors. Downstream pathways of OX(2)R other than the histaminergic system might play an important role in the maintenance of sleep/wake states.