Duration of PCR positivity by type of respiratory virus among children using a multiplex PCR test.

Prolonged positive polymerase chain reaction (PCR) results, irrespective of the transmission risk, can lead to prolonged restrictions on daily activities and infection precaution interventions. Studies evaluating the duration of PCR positivity for multiple pathogens in a single patient cohort are scarce. This study aimed to evaluate and compare the durations of PCR positivity for multiple respiratory viruses among children and adolescents. This retrospective study was conducted between April 2018 and March 2024 using a multiplex PCR respiratory panel for symptomatic children and adolescents who had at least two tests within 90 days of study period, with the first PCR test positive. The rate and likelihood of persistent PCR positivity were evaluated for multiple respiratory viruses. For 1325 positive results, repeat tests were conducted within 90 days. The persistent PCR positivity rate at repeat testing decreased over time (60.6%, Days 1-15 and 21.7%, Days 76-90, after the first test). In multivariate logistic regression analysis, an increased likelihood of persistent PCR positivity was observed for rhinovirus/enterovirus and adenovirus, whereas decreased likelihood of persistent positivity was seen in influenza and seasonal coronaviruses, compared with parainfluenza viruses. Persistent PCR positivity is common for multiple respiratory viruses in symptomatic children.

Cilostazol treats transient heart failure caused by ATP1A3 variant-associated polymicrogyria.

BACKGROUND: Some patients with ATP1A3 variant-associated polymicrogyria have recurrent transient heart failure. However, effective treatment for the transient cardiac condition remains to be elucidated. CASE REPORT: The patient started experiencing focal motor onset seizures in 12 h after birth, revealing bilateral diffuse polymicrogyria. The patient also experienced transient bradycardia (sinus bradycardia) attacks from 15 days old. Echocardiography revealed a reduced ejection fraction; however, no obvious electrocorticogram or electroencephalogram abnormalities were observed during the attacks. Initially, the attacks occurred in clusters daily. They later decreased in frequency, occurring at monthly intervals. Repeated episodes of transient bradycardia attacks and polymicrogyria indicated possible ATP1A3 gene abnormality and genetic testing revealed a novel heterozygous ATP1A3 variant (NM_152296: exon22:c.2977_2982del:p.(Glu993_Ile994del)), which was not found in the patient's parents. Cilostazol was administered at 3 months old for recurrent transient bradycardia attacks. Cilostazol significantly shortened the duration of bradycardia episodes and prolonged the interval between attacks. Cilostazol also effectively treats transient symptomatic bradycardia. CONCLUSION: Cilostazol could be a treatment option for recurrent transient bradycardia attacks associated with ATP1A3 gene abnormalities and polymicrogyria.

CD8+ Regulatory T Cells Induced by Lipopolysaccharide Improve Mouse Endotoxin Shock.

Sepsis is a systemic inflammatory disease caused by a bacterial infection that leads to severe mortality, especially in elderly patients, because of an excessive immune response and impaired regulatory functions. Antibiotic treatment is widely accepted as the first-line therapy for sepsis; however, its excessive use has led to the emergence of multidrug-resistant bacteria in patients with sepsis. Therefore, immunotherapy may be effective in treating sepsis. Although CD8+ regulatory T cells (Tregs) are known to have immunomodulatory effects in various inflammatory diseases, their role during sepsis remains unclear. In this study, we investigated the role of CD8+ Tregs in an LPS-induced endotoxic shock model in young (8-12 wk old) and aged (18-20 mo old) mice. The adoptive transfer of CD8+ Tregs into LPS-treated young mice improved the survival rate of LPS-induced endotoxic shock. Moreover, the number of CD8+ Tregs in LPS-treated young mice increased through the induction of IL-15 produced by CD11c+ cells. In contrast, LPS-treated aged mice showed a reduced induction of CD8+ Tregs owing to the limited production of IL-15. Furthermore, CD8+ Tregs induced by treatment with the rIL-15/IL-15Rα complex prevented LPS-induced body wight loss and tissue injury in aged mice. In this study, to our knowledge, the induction of CD8+ Tregs as novel immunotherapy or adjuvant therapy for endotoxic shock might reduce the uncontrolled immune response and ultimately improve the outcomes of endotoxic shock.

D­allose enhances the efficacy of hydroxychloroquine against Lewis lung carcinoma cell growth by inducing autophagy.

Various cancer cells require massive amounts of glucose as an energy source for their dysregulated growth. Although D­allose, a rare sugar, inhibits tumor cell growth via inhibition of glucose uptake, a few cells can survive after treatment. However, the mechanism by which D­allose­resistant cells are generated remains unclear. Here, we investigated the properties of D­allose­resistant cells and evaluated the efficacy of combined treatment with this rare sugar and antitumor drugs. To this end, we established a D­allose­resistant tumor cell line and prepared a C57BL/6J mouse tumor xenograft model using Lewis lung carcinoma (LLC) cells. Xenograft­bearing mice were treated with D­allose (9 g/kg) and/or hydroxychloroquine (HCQ, 60 mg/kg), an autophagy inhibitor, for two weeks. Although D­allose inhibited LLC cell growth in a dose­dependent manner, a few cells survived. The upregulation of LC3­II, a classical autophagy marker, and the downregulation of mTOR and its downstream molecule Beclin1 were observed in established D­allose­resistant LLC cells, which were more sensitive to cell death induced by HCQ. Similarly, in the tumor xenograft model, the tumor volume in mice co­treated with D­allose and HCQ was considerably smaller than that in untreated or HCQ­treated mice. Importantly, the administration of D­allose induced autophagy selectively at the tumor site of the xenograft­bearing mice. These results provide a new therapeutic strategy targeting autophagy which is induced in tumor cells by D­allose administration, and may be used to improve therapies for lung cancer.

Foramen magnum stenosis and midface hypoplasia in C-type natriuretic peptide-deficient rats and restoration by the administration of human C-type natriuretic peptide with 53 amino acids.

C-type natriuretic peptide (CNP)-knockout (KO) rats exhibit impaired skeletal growth, with long bones shorter than those in wild-type (WT) rats. This study compared craniofacial morphology in the CNP-KO rat with that in the Spontaneous Dwarf Rat (SDR), a growth hormone (GH)-deficient model. The effects of subcutaneous administration of human CNP with 53 amino acids (CNP-53) from 5 weeks of age for 4 weeks on craniofacial morphology in CNP-KO rats were also investigated. Skulls of CNP-KO rats at 9 weeks of age were longitudinally shorter and the foramen magnum was smaller than WT rats. There were no differences in foramen magnum stenosis and midface hypoplasia between CNP-KO rats at 9 and 33 weeks of age. These morphological features were the same as those observed in CNP-KO mice and activated fibroblast growth factor receptor 3 achondroplasia-phenotype mice. In contrast, SDR did not exhibit foramen magnum stenosis and midface hypoplasia, despite shorter stature than in control rats. After administration of exogenous CNP-53, the longitudinal skull length and foramen magnum size in CNP-KO rats were significantly greater, and full or partial rescue was confirmed. The synchondrosis at the cranial base in CNP-KO rats is closed at 9 weeks, but not at 4 weeks of age. In contrast, synchondrosis closure in CNP-KO rats treated with CNP-53 was incomplete at 9 weeks of age. Administration of exogenous CNP-53 accelerated craniofacial skeletogenesis, leading to improvement in craniofacial morphology. As these findings in CNP-KO rats are similar to those in patients with achondroplasia, treatment with CNP-53 or a CNP analog may be able to restore craniofacial morphology and foramen magnum size as well as short stature.

[A Case of Synchronous Bilateral Neuroendocrine Ductal Carcinoma In Situ].

Neuroendocrine ductal carcinoma in situ(NE-DCIS)is a unique subtype of ductal carcinoma in situ(DCIS)that is not described in the general rules for clinical and pathological recording of breast cancer. NE-DCIS is described as an unusual variant of DCIS in the 2012 World Health Organization(WHO)classification. The chief complaint in NE-DCIS is hemorrhagic nipple discharge. The histological characteristics of NE-DCIS are solid growth of cancer cells with granular and spindle-shaped nuclei. Histologically, NE-DCIS is suggestive of low malignancy but a poor prognosis of neuroendocrine carcinoma of the breast has been reported. The report by Honami et al was the only other report of synchronous bilateral neuroendocrine ductal carcinoma in situ. We report the second case of NE-DCIS diagnosed synchronously in both breasts in a patient who had visited our outpatient clinic with hemorrhagic nipple discharge.

Exogenous C-type natriuretic peptide restores normal growth and prevents early growth plate closure in its deficient rats.

Signaling by C-type natriuretic peptide (CNP) and its receptor, natriuretic peptide receptor-B, is a pivotal stimulator of endochondral bone growth. We recently developed CNP knockout (KO) rats that exhibit impaired skeletal growth with early growth plate closure. In the current study, we further characterized the phenotype and growth plate morphology in CNP-KO rats, and the effects of exogenous CNP in rats. We used CNP-53, an endogenous form of CNP consisting of 53 amino acids, and administered it for four weeks by continuous subcutaneous infusion at 0.15 or 0.5 mg/kg/day to four-week old CNP-KO and littermate wild type (WT) rats. We demonstrated that CNP-KO rats were useful as a reproducible animal model for skeletal dysplasia, due to their impairment in endochondral bone growth. There was no significant difference in plasma bone-turnover markers between the CNP-KO and WT rats. At eight weeks of age, growth plate closure was observed in the distal end of the tibia and the calcaneus of CNP-KO rats. Continuous subcutaneous infusion of CNP-53 significantly, and in a dose-dependent manner, stimulated skeletal growth in CNP-KO and WT rats, with CNP-KO rats being more sensitive to the treatment. CNP-53 also normalized the length of long bones and the growth plate thickness, and prevented growth plate closure in the CNP-KO rats. Using organ culture experiment of fetal rat tibia, gene set enrichment analysis indicated that CNP might have a negative influence on mitogen activated protein kinase signaling cascades in chondrocyte. Our results indicated that CNP-KO rats might be a valuable animal model for investigating growth plate physiology and the mechanism of growth plate closure, and that CNP-53, or its analog, may have the potential to promote growth and to prevent early growth plate closure in the short stature.

Nosocomial Outbreak of Upper Respiratory Tract Infection With ß-Lactamase-Negative Ampicillin-Resistant Nontypeable Haemophilus influenzae.

OBJECTIVETo describe the epidemiologic features of an outbreak of an acute respiratory tract infection (ARI) caused by ß-lactamase-negative ampicillin-resistant (BLNAR) nontypeable Haemophilus influenzae (NTHi) in an acute-care ward.DESIGNCross-sectional case-control study.SETTINGAn acute-care ward (ward A) in a general hospital of Kochi in western Japan.METHODSPatients who shared a room with an index patient and all staff in ward A were screened and followed from July 1 to August 31, 2015. Sputum or throat swab samples were collected from participants and tested by culture and polymerase chain reaction (PCR). The association between detected pathogens and ARI development among all participants was examined. A case-control study was conducted to identify risk factors for disease.RESULTSIn total, 78 participants, including the index patient, were enrolled. Of all participants, 27 (34.6%) developed mild respiratory symptoms during a 3-week period: 24 were diagnosed as upper respiratory tract infections, and 3 were diagnosed as lower respiratory tract infections. The presence of BLNAR NTHi was confirmed in 13 participants, and multilocus sequence typing demonstrated that these isolates belonged to sequence type 159. All isolates showed identical pulsed-field gel electrophoresis patterns. The presence of BLNAR NTHi was strongly associated with ARI development, whereas viruses were not associated with the disease. Multivariate analyses demonstrated that a history of contact with the index patient was independently associated with ARI caused by BLNAR NTHi.CONCLUSIONSBLNAR NTHi has the potential to cause upper respiratory tract infections among adults and to spread rapidly in hospital settings.Infect Control Hosp Epidemiol 2018;39:652-659.

[A Case of Encapsulated Papillary Carcinoma of the Breast].

An 84-year-old woman was revealed to have focal asymmetric density(FAD)based on mammography, and ultrasonography showed a 0.5 cm sized cyst in the left breast. It gradually increased in size and contained solid components. A core needle biopsy revealed an intracystic papillary carcinoma of the breast. Partial mastectomy and sentinel lymph node biopsy were performed. Histopathological examination revealed an encapsulated papillary carcinoma and a papillary lesion surrounded by a thick fibrous capsule. Myoepithelial cells were not found at the periphery of the lesion or within fibrovascular cores. Currently, it is classified as non-invasive carcinoma, and the patient has a good prognosis.

Successful transcatheter arterial antimicrobial and steroid therapy for refractory liver abscess in chronic granulomatous disease: A case report and review of literature.

Hepatic abscess in chronic granulomatous disease (CGD) is very refractory and frequently requires multiple surgeries with frequent morbidities. Although surgical interventions are often required, patients are often not able to have surgery for various reasons. We present the case of a 21-year-old man with recurrent hepatic abscess in CGD. We could not provide surgical interventions due to the lack of a fluid cavity and the patient's refusal, and therefore we administered transcatheter arterial antimicrobial and steroid therapy. He did not have any exacerbation for more than 18 months after the final transcatheter treatment. This is the first reported case of successful transcatheter arterial antimicrobial and steroid therapy for refractory hepatic abscess in CGD. Although the patient's burden and medical cost were not inconsequential, this case shows that the transcatheter arterial antimicrobial and steroid therapy may be a treatment option for patients who are not candidates for surgical interventions.

Drug-Repositioning Screening for Keap1-Nrf2 Binding Inhibitors using Fluorescence Correlation Spectroscopy.

The Kelch-like ECH-associating protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) signaling pathway is the major regulator of cytoprotective responses to oxidative and electrophilic stress. The Cul3/Keap1 E3 ubiquitin ligase complex interacts with Nrf2, leading to Nrf2 ubiquitination and degradation. In this study, we focused on the disruption of the Keap1-Nrf2 interaction to upregulate Nrf2 expression and the transcription of ARE-controlled cytoprotective oxidative stress response enzymes, such as HO-1. We completed a drug-repositioning screening for inhibitors of Keap1-Nrf2 protein-protein interactions using a newly established fluorescence correlation spectroscopy (FCS) screening system. The binding reaction between Nrf2 and Keap1 was successfully detected with a KD of 2.6 µM using our FCS system. The initial screening of 1,633 drugs resulted in 12 candidate drugs. Among them, 2 drugs significantly increased Nrf2 protein levels in HepG2 cells. These two promising drugs also upregulated ARE gene promoter activity and increased HO-1 mRNA expression, which confirms their ability to dissociate Nrf2 and Keap1. Thus, drug-repositioning screening for Keap1-Nrf2 binding inhibitors using FCS enabled us to find two promising known drugs that can induce the activation of the Nrf2-ARE pathway.

Loop diuretics affect skeletal myoblast differentiation and exercise-induced muscle hypertrophy.

Muscle wasting or sarcopenia contributes to morbidity and mortality in patients with cancer, renal failure, or heart failure, and in elderly individuals. Na+-K+-2Cl- cotransporter 1 (NKCC1) is highly expressed in mammalian skeletal muscle, where it contributes to the generation of membrane ion currents and potential. However, the physiologic function of NKCC1 in myogenesis is unclear. We investigated this issue using the NKCC1 inhibitors bumetanide and furosemide, which are commonly used loop diuretics. NKCC1 protein levels increased during C2C12 murine skeletal myoblast differentiation, similarly to those of the myogenic markers myogenin and myosin heavy chain (MHC). NKCC1 inhibitors markedly suppressed myoblast fusion into myotubes and the expression of myogenin and MHC. Furthermore, phosphorylated and total NKCC1 levels were elevated in mouse skeletal muscles after 6 weeks' voluntary wheel running. Immunofluorescence analyses of myofiber cross-sections revealed more large myofibers after exercise, but this was impaired by daily intraperitoneal bumetanide injections (0.2 or 10 mg/kg/day). NKCC1 plays an essential role in myogenesis and exercise-induced skeletal muscle hypertrophy, and sarcopenia in patients with renal or heart failure may be attributable to treatment with loop diuretics.

[A Case of Occult Breast Cancer].

We report a case of occult breast cancer. A 61-years-old woman underwent tumorectomy of right axillary mass. Pathological diagnosis was adenocarcinoma. Two years after, right axillary mass was discovered again. Wide local excision, axillary lymph node dissection and radiation therapy of the breast was performed. Pathological findings showed lymph node metastasis of breast cancer, or primary cancer of the axially tail of the breast. Ten months after second operation, she presented an axillary mass again. She underwent resection of the axillary tumor. The pathological findings showed lymph node metastasis of breast cancer. There was no evidence of primary tumor of the breast during the period. We suspected lymph node metastasis of occult breast cancer. Irradiation was administered to the right axilla, and she is receiving endocrine therapy.

[A Case of Breast Carcinoma Associated with Osteoclast-Like Giant Cells].

Mammary carcinoma with osteoclast-like giant cells is uncommon, and its onset mechanism and malignancy are unknown. We report a case of mammary carcinoma with osteoclast-like giant cells. A 41-year-old woman noticed a lump in her left breast. Ultrasound sonography findings suggested breast cancer. A core needle biopsy revealed invasive ductal carcinoma of the breast. Modified radicalmastectomy and sentinell ymph node biopsy were performed. Histopathologicalexamination revealed papillotubular carcinoma with osteoclast-like giant cells. Cells were positive for estrogen receptor and progesterone, and negative for HER2. MIB-1 index was under 5%. The giant cells were generally associated with an inflammatory, fibroblastic, hyper-vascular stroma. The carcinomatous part of the lesion was most frequently a well-to moderately differentiated invasive ductalcarcinoma. Immunohistochemicaland ultrastructuralstudies suggested that the osteoclast-like giant cells were of stromalhistiocytic origin. To understand biochemicalfindings of this carcinoma, more case studies are required to be reported.

[A Case of Axillary Arterial Bleeding after Axillary Metastatic Lymph Node Necrosis during Treatment with Paclitaxel and Bevacizumabfor Breast Cancer].

A 44-year-old woman was diagnosed cT4bcN3cM1(LYM), Stage IV triple-negative breast cancer.Enhanced computed tomography revealed ipsilateral axillary lymph node metastasis, 10 cm in diameter.The supraclavicular and cervical lymph nodes also had metastases.She received paclitaxel(90mg/m2, on days 1, 8, and 15 every 4 weeks)in combination with bevacizumab(10mg/kg, on days 1 and 15 every 28 days).Her height was 165 cm, and her body weight was 100 kg.After 1 course of chemotherapy, a metastatic axillary lymph node with necrotic changes was removed spontaneously.A few days later, she experienced severe bleeding from her axillary artery, and she went into hypovolemic shock.Despite undergoing surgical hemostasis, the bleeding recurred twice, so we performed coil embolization of her subclavian artery.Thirty -five days after the first occurrence of bleeding, the patient died of sepsis and ARDS due to left arm necrosis.Bevacizumab is effective for the treatment of large tumors, but when the tumor is close to an artery, clinicians should be wary of fatal bleeding after necrosis.

Co-expression of S100A14 and S100A16 correlates with a poor prognosis in human breast cancer and promotes cancer cell invasion.

BACKGROUND: S100 family proteins have recently been identified as biomarkers in various cancers. Of this protein family, S100A14 and S100A16 are also believed to play an important role in tumor progression. The aim of the present study was to clarify the clinical significance and functional role of these molecules in breast cancer. METHODS: In a clinical study, an immunohistochemical analysis of S100A14 and S100A16 expression in archival specimens of primary tumors of 167 breast cancer patients was performed. The relationship of S100A14 and S100A16 expression to patient survival and clinicopathological variables was statistically analyzed. In an experimental study, the subcellular localization and function of these molecules was examined by using the human breast cancer cell lines MCF7 and SK-BR-3, both of which highly express S100A14 and S100A16 proteins. Cells transfected with expression vectors and siRNA for these genes were characterized using in vitro assays for cancer invasion and metastasis. RESULTS: Immunohistochemical analysis of 167 breast cancer cases showed strong cell membrane staining of S100A14 (53% of cases) and S100A16 (31% of cases) with a significant number of cases with co-expression (p < 0.001). Higher expression levels of these proteins were significantly associated with a younger age (<60 years), ER-negative status, HER2-positive status and a poorer prognosis. Co-expression of the two proteins showed more aggressive features with poorer prognosis. In the human breast cancer cell lines MCF7 and SK-BR-3, both proteins were colocalized on the cell membrane mainly at cell-cell attachment sites. Immunoprecipitation and immunofluorescence analyses demonstrated that the 100A14 protein can bind to actin localized on the cell membrane in a calcium-independent manner. A Boyden chamber assay showed that S100A14 and S100A16 knockdown substantially suppressed the invasive activity of both cell lines. Cell motility was also inhibited by S100A14 knockdown in a modified dual color wound-healing assay. CONCLUSIONS: To our knowledge, this is the first report showing the correlation of expression of S100A14, S100A16, and co-expression of these proteins with poor prognosis of breast cancer patients. In addition, our findings indicate that S100A14 and S100A16 can promote invasive activity of breast cancer cells via an interaction with cytoskeletal dynamics. S100A14 and S100A16 might be prognostic biomarkers and potential therapeutic targets for breast cancer.

Adaptive significance of gall formation for a gall-inducing aphids on Japanese elm trees.

Insect galls are abnormal plant tissues induced by external stimuli from parasitizing insects. It has been suggested that the stimuli include phytohormones such as auxin and cytokinins produced by the insects. In our study on the role of hormones in gall induction by the aphid Tetraneura nigriabdominalis, it was found that feedback regulation related to auxin and cytokinin activity is absent in gall tissues, even though the aphids contain higher concentrations of those phytohormones than do plant tissues. Moreover, jasmonic acid signaling appears to be compromised in gall tissue, and consequently, the production of volatile organic compounds, which are a typical defense response of host plants to herbivory, is diminished. These findings suggest that these traits of the gall tissue benefit aphids, because the gall tissue is highly sensitive to auxin and cytokinin, which induce and maintain it. The induced defenses against aphid feeding are also compromised. The abnormal responsiveness to phytohormones is regarded as a new type of extended phenotype of gall-inducing insects.

Multiple metastatic malignant melanoma presenting intraluminal gallbladder bleeding.

We report a case of malignant melanoma of unknown primary origin presenting metastasis in various organs as well as intraluminal gallbladder bleeding due to gallbladder metastasis. A 58-year-old woman was diagnosed with stage IV metastatic malignant melanoma. Because she exhibited acute cholecystitis and hemobilia due to malignant melanoma of the gallbladder, laparoscopic cholecystectomy was performed to relieve the symptoms. The resected gallbladder specimen showed a pedunculated black mass indicating malignant melanoma. Pathologic examination and immunohistochemical analysis revealed malignant melanoma of the gallbladder. Only a few cases of gallbladder malignant melanoma presenting hemobilia have been reported; here we present our case, including the experience of multidisciplinary treatment.

Novel 1p tumour suppressor Dnmt1-associated protein 1 regulates MYCN/ataxia telangiectasia mutated/p53 pathway.

Neuroblastoma (NB) is a paediatric solid tumour which originates from sympathetic nervous tissues. Deletions in chromosome 1p are frequently found in unfavourable NBs and are correlated with v-myc avian myelocytomatosis viral oncogene neuroblastoma derived homolog (MYCN) amplification; however, it remains to be elucidated how the 1p loss contributes to MYCN-related oncogenic processes in NB. In this study, we identified the role of Dnmt1-associated protein 1 (DMAP1), coded on chromosome 1p34, in the processes. We studied the expression and function of DMAP1 in NB and found that low-level expression of DMAP1 related to poor prognosis, unfavourable histology and 1p Loss of heterozygosity (LOH) of primary NB samples. Intriguingly, DMAP1 induced ataxia telangiectasia mutated (ATM) phosphorylation and focus formation in the presence of a DNA damage reagent, doxorubicin. By DMAP1 expression in NB and fibroblasts, p53 was activated in an ATM-dependent manner and p53-downstream pro-apoptotic Bcl-2 family molecules were induced at the mRNA level, resulting in p53-induced apoptotic death. BAX and p21(Cip1/Waf1) promoter activity dependent on p53 was clearly up-regulated by DMAP1. Further, MYCN transduction in MYCN single-copy NB cells accelerated doxorubicin (Doxo)-induced apoptotic cell death; MYCN is implicated in DMAP1 protein stabilisation and ATM phosphorylation in these situations. DMAP1 knockdown attenuated MYCN-dependent ATM phosphorylation and NB cell apoptosis. Together, DMAP1 appears to be a new candidate for a 1p tumour suppressor and its reduction contributes to NB tumourigenesis via inhibition of MYCN-related ATM/p53 pathway activation.

In vitro selection of a peptide antagonist of growth hormone secretagogue receptor using cDNA display.

G protein-coupled receptors (GPCRs) are major drug targets, and their ligands are currently being explored and developed by many pharmaceutical companies and independent researchers. Class A (rhodopsin-like) GPCRs compose a predominant GPCR family; therefore, class A GPCR ligands are in demand. Growth hormone secretagogue receptor (GHS-R) is a class A GPCR that stimulates food intake by binding to its peptide ligand, ghrelin. Therefore, antagonists of GHS-R are expected to exert antiobesity function. In this article, we describe the use of cDNA display to screen for successfully and identify an antagonistic peptide of GHS-R. The antagonistic peptide inhibited the ghrelin-induced increase in intracellular Ca(2+) in vitro (IC(50) = approximately 10 µM) and repressed the contraction of isolated animal stomach in response to ghrelin. Furthermore, peripheral administration of the peptide inhibited the food intake of mice. This work provides new insight into the development of antiobesity drugs and describes a method for the discovery of unique peptide ligands for class A GPCRs.