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Mattern C, Pourette D, Andriamandimby SF, Rabarison J, Darsot A, Ralaizara B, Vray M, Shimakawa Y, Giles-Vernick T. Enjeux et difficultés de l'accès aux traitements pour la prise en charge de l'hépatite B chronique à Madagascar : étude qualitative auprès des soignants et personnes atteintes. Rev Epidemiol Sante Publique 2023; 71:102088. [PMID: 37352795 DOI: 10.1016/j.respe.2023.102088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 03/24/2023] [Accepted: 05/15/2023] [Indexed: 06/25/2023] Open
Abstract
OBJECTIVES Madagascar faces many difficulties in accessing diagnosis and treatment of hepatitis B. The prevalence of chronic hepatitis B infection is estimated at 6.9%. The costs associated with screening and treatment are high and not easily accessible. This article proposes a reflection on the challenges and difficulties of access to diagnosis and treatment for patients with chronic hepatitis B. METHOD The "Neo Vac" study aimed to document the life paths of people living with chronic hepatitis B, their difficulties and their perceptions of HBV. Twenty-three semi-structured interviews were conducted in 2019 in Antananarivo with patients and gastroenterologists. RESULTS The study describes the numerous obstacles that mark the therapeutic pathways of chronic HBV patients. The first result indicates lack of knowledge of the disease by chronic HBV patients and the varied circumstances in which the disease is discovered. None of the persons interviewed had been screened on their own initiative, the screening having taken place during prenatal consultations or emergency hospitalizations or during a morbidity episode. The care pathway was characterized by doubt and anxiety due to lack of knowledge about the possible disease outcome and concern about the costs of care. DISCUSSION Little known by the population and health professionals, hepatitis B is rarely the subject of voluntary screening and is most often detected during an apparently unrelated health event. The exorbitant cost of treatment for patients, the cost of medical analyses and secondary costs, and the unavailability of follow-up tests outside the capital constitute barriers to access to care that are insurmountable for the majority of the Malagasy population. CONCLUSIONS This first qualitative study on the experiences of HBV-infected persons in terms of access to care and treatment in Madagascar underlines the extent to which access to treatment remains limited, due to the absence of a national policy for the prevention, screening and management of hepatitis B, which remains a highly neglected and unrecognized disease in Madagascar as well as internationally.
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Affiliation(s)
- C Mattern
- Equipe Santé & Sciences sociales, Unité d'épidémiologie et de recherche clinique Institut Pasteur de Madagascar, BP 1274 Ambatofotsikely Avaradoha, 101 Antananarivo, Madagascar.
| | - D Pourette
- Institut de recherche pour le développement, UMR Ceped (IRD, Université Paris Cité, Inserm), Institut Convergences Migrations. Paris, 75006, France
| | - S F Andriamandimby
- Unité de virologie, Institut Pasteur de Madagascar, BP 1274 Ambatofotsikely Avaradoha, 101 Antananarivo, Madagascar
| | - J Rabarison
- Unité de virologie, Institut Pasteur de Madagascar, BP 1274 Ambatofotsikely Avaradoha, 101 Antananarivo, Madagascar
| | - A Darsot
- Equipe Santé & Sciences sociales, Unité d'épidémiologie et de recherche clinique Institut Pasteur de Madagascar, BP 1274 Ambatofotsikely Avaradoha, 101 Antananarivo, Madagascar
| | - B Ralaizara
- Equipe Santé & Sciences sociales, Unité d'épidémiologie et de recherche clinique Institut Pasteur de Madagascar, BP 1274 Ambatofotsikely Avaradoha, 101 Antananarivo, Madagascar
| | - M Vray
- Institut Pasteur 25 rue du Dr Roux 75015 Paris, Inserm 101 rue de Tolbiac 75013 Paris, France
| | - Y Shimakawa
- Unité d'épidémiologie des maladies émergentes, Institut Pasteur, 25 rue du Dr Roux 75015 Paris, France
| | - T Giles-Vernick
- Laboratoire d'anthropologie et écologie de l'émergence des maladies, Institut Pasteur, 25 rue du Dr Roux 75015 Paris, France
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2
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Darsot A, Mattern C, Shimakawa Y, Giles-Vernick T, Pourette D. Barriers to the access to hepatitis B diagnosis and prevention in Madagascar: a qualitative approach. Eur J Public Health 2020. [DOI: 10.1093/eurpub/ckaa166.1411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
The overall seroprevalence of HBsAg is estimated at 6.9% in adults in Madagascar. The most frequently used means of prevention remain screening and vaccination, but their implementation encounters structural and individual difficulties. An anthropological study was conducted in Madagascar in 2018-2019 in order to identify the care pathways of people with chronic HBV infection and the barriers to the vaccination, screening, and care.
Methods
Semi-directive interviews were conducted with twenty patients known to be chronically infected with HBV and three hepato-gastroenterologists at the central hospital in Antananarivo.
Results
None of the patients voluntarily got tested for HBV. Only two patients had known that there is a vaccine against this infection before they got the diagnosis of hepatitis B, and both were medical students. Patients' lack of knowledge about hepatitis B before the diagnosis (name of the disease, modes of transmission, signs, treatment, and prevention) influenced the therapeutic choice. For 16 patients, screening and vaccination of their entourage remained problematic; they do not have the financial resources for the screening and vaccination of their relatives. Moreover, it was difficult for them to make their relatives understand the interest of being screened and vaccinated because patients' entourages do not feel sick. To break the transmission, some patients prefer unofficial prevention methods. The significant costs related to medical follow-up (medical examinations and treatments) are entirely at the patient's own expense.
Conclusions
The low political commitment to hepatitis B in Madagascar leads to the inexistence of care policy and specific actions in terms of prevention. These results underline the urgency of developing a national plan and better communication strategies for the prevention of this infection in Madagascar.
Key messages
This study highlights the lack of knowledge about hepatitis B and the difficulties in access to care and vaccination. Priority is to develop a communication tool to raise the awareness about hepatitis B.
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Affiliation(s)
- A Darsot
- Epidemiology, Institut Pasteur, Madagascar, Madagascar
| | - C Mattern
- Epidemiology, Institut Pasteur, Madagascar, Madagascar
| | - Y Shimakawa
- Epidemiology of Emerging Diseases, Institut Pasteur, Paris, France
| | - T Giles-Vernick
- Anthropology and Ecology of Emerging Diseases, Institut Pasteur, Paris, France
| | - D Pourette
- Anthropology, Institut de Recherche pour le Developpement, Paris, France
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3
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El Kassas M, Funk AL, Salaheldin M, Shimakawa Y, Eltabbakh M, Jean K, El Tahan A, Sweedy AT, Afify S, Youssef NF, Esmat G, Fontanet A. Increased recurrence rates of hepatocellular carcinoma after DAA therapy in a hepatitis C-infected Egyptian cohort: A comparative analysis. J Viral Hepat 2018; 25:623-630. [PMID: 29274197 DOI: 10.1111/jvh.12854] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 10/09/2017] [Indexed: 12/13/2022]
Abstract
In Egypt, hepatocellular carcinoma (HCC) is the most common form of cancer and direct-acting antivirals (DAA) are administered on a large scale to patients with chronic HCV infection to reduce the risk. In this unique setting, we aimed to determine the association of DAA exposure with early-phase HCC recurrence in patients with a history of HCV-related liver cancer. This was a prospective cohort study of an HCV-infected population from one Egyptian specialized HCC management centre starting from the time of successful HCC intervention. The incidence rates of HCC recurrence between DAA-exposed and nonexposed patients were compared, starting from date of HCC complete radiological response and censoring after 2 years. DAA exposure was treated as time varying. Two Poisson regressions models were used to control for potential differences in the exposed and nonexposed group; multivariable adjustment and balancing using inverse probability of treatment weighting (IPTW). We included 116 patients: 53 treated with DAAs and 63 not treated with DAAs. There was 37.7% and 25.4% recurrence in each group after a median of 16.0 and 23.0 months of follow-up, respectively. Poisson regression using IPTW demonstrated an association between DAAs and HCC recurrence with an incidence rate ratio of 3.83 (95% CI: 2.02-7.25), which was similar in the multivariable-adjusted model and various sensitivity analyses. These results add important evidence towards the possible role of DAAs in HCC recurrence and stress the need for further mechanistic studies and clinical trials to accurately confirm this role and to identify patient characteristics that may be associated with this event.
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Affiliation(s)
- M El Kassas
- Endemic Medicine Department, Faculty of Medicine, Helwan University, Cairo, Egypt
| | - A L Funk
- Emerging Disease Epidemiology Unit, Institut Pasteur, Paris, France
| | - M Salaheldin
- Tropical Medicine Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Y Shimakawa
- Emerging Disease Epidemiology Unit, Institut Pasteur, Paris, France
| | - M Eltabbakh
- Tropical Medicine Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - K Jean
- Laboratoire MESuRS (EA 4628), Conservatoire National Des Arts et Métiers, Paris, France.,Unité PACRI, Institut Pasteur, Conservatoire National des Arts et Métiers, Paris, France
| | - A El Tahan
- New Cairo Viral Hepatitis Treatment Unit, Cairo, Egypt
| | - A T Sweedy
- New Cairo Viral Hepatitis Treatment Unit, Cairo, Egypt
| | - S Afify
- National Hepatology and Tropical Medicine Research Institute, Cairo, Egypt
| | - N F Youssef
- Medical Surgical Nursing Department, Faculty of Nursing, Cairo University, Cairo, Egypt
| | - G Esmat
- Endemic Medicine and Hepato-Gastroenterology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - A Fontanet
- Emerging Disease Epidemiology Unit, Institut Pasteur, Paris, France.,Unité PACRI, Institut Pasteur, Conservatoire National des Arts et Métiers, Paris, France
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4
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El Kassas M, Funk AL, Abd El Latif Y, Vasiliu A, Sherief A, Shimakawa Y, Youssef N, El Tahan A, Elbadry M, Farid AM, El Shazly Y, Doss W, Esmat G, Fontanet A. Letter: concordance of SVR4 and SVR12 following direct-acting anti-viral treatment in Egypt. Aliment Pharmacol Ther 2018; 47:1564-1566. [PMID: 29878419 DOI: 10.1111/apt.14628] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- M El Kassas
- Endemic Medicine Department, Faculty of Medicine, Helwan University, Cairo, Egypt
| | - A L Funk
- Emerging Disease Epidemiology Unit, Institut Pasteur, Paris, France
| | - Y Abd El Latif
- Tropical Medicine Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - A Vasiliu
- Emerging Disease Epidemiology Unit, Institut Pasteur, Paris, France
| | - A Sherief
- Tropical Medicine Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Y Shimakawa
- Emerging Disease Epidemiology Unit, Institut Pasteur, Paris, France
| | - N Youssef
- Medical Surgical Nursing Department, Faculty of Nursing, Cairo University, Cairo, Egypt
| | - A El Tahan
- New Cairo Viral Hepatitis Treatment Unit, Cairo, Egypt
| | - M Elbadry
- Tropical Medicine and Gastroenterology Department, Faculty of Medicine, Aswan University, Sahary City, Egypt
| | - A M Farid
- Tropical Medicine Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Y El Shazly
- Egyptian National Committee for Control of Viral Hepatitis, Cairo, Egypt
| | - W Doss
- Egyptian National Committee for Control of Viral Hepatitis, Cairo, Egypt
| | - G Esmat
- Egyptian National Committee for Control of Viral Hepatitis, Cairo, Egypt
| | - A Fontanet
- Emerging Disease Epidemiology Unit, Institut Pasteur, Paris, France.,Institut Pasteur, Conservatoire National des Arts et Métiers, Unité PACRI, Paris, France
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5
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Keane E, Funk AL, Shimakawa Y. Systematic review with meta-analysis: the risk of mother-to-child transmission of hepatitis B virus infection in sub-Saharan Africa. Aliment Pharmacol Ther 2016; 44:1005-1017. [PMID: 27630001 DOI: 10.1111/apt.13795] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/28/2016] [Accepted: 08/17/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND The risk of mother-to-child transmission of hepatitis B virus (HBV) has been quoted as 70-90% among women positive for hepatitis B surface antigen (HBsAg) and e antigen (HBeAg), and 5-30% among HBsAg-positive HBeAg-negative women. These risks are derived from Asia; little is known about sub-Saharan Africa. AIM To determine the risk of mother-to-child transmission in sub-Saharan Africa, according to maternal HBeAg and type of prophylaxis. METHODS We searched Medline, Global Health, Embase, African Journals Online and African Index Medicus. We included observational or interventional studies that enrolled infants of HBV-infected women, and that tested for HBsAg or HBV DNA between 3 and 12 months of age. RESULTS Fifteen articles from 11 African countries were included. Among HBeAg-positive women, the pooled risk was 38.3% (95% CI: 7.0-74.4%) without prophylaxis, which was significantly lower than the lower bound of 70-90% risk in the literature (P = 0.007). Among HBeAg-negative women, the pooled risk was 4.8% (95% CI: 0.1-13.3%) without prophylaxis, which lays within the lower range of the 5-30% risk in Asia. By extrapolating the pooled transmission risks to the number of births to infectious mothers, an estimated 1% of newborns (n = 367 250) are annually infected with HBV at birth in sub-Saharan Africa. CONCLUSIONS Compared to Asia, the risk of mother-to-child transmission is low in sub-Saharan Africa. However, the annual number of infants perinatally infected with HBV is twice the number of incident paediatric HIV infections in sub-Saharan Africa (n = 190 000). This highlights the importance of preventing mother-to-child transmission of HBV in sub-Saharan Africa, which has been long neglected.
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Affiliation(s)
- E Keane
- École Pasteur/CNAM de Santé Publique, Paris, France.,Mater Misercicordiae University Hospital, Dublin, Ireland
| | - A L Funk
- Unité d'Épidémiologie des Maladies Émergentes, Institut Pasteur, Paris, France
| | - Y Shimakawa
- Unité d'Épidémiologie des Maladies Émergentes, Institut Pasteur, Paris, France.
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6
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Shimakawa Y, Njai HF, Takahashi K, Berg L, Ndow G, Jeng-Barry A, Ceesay A, Tamba S, Opoku E, Taal M, Akbar SMF, Arai M, D'Alessandro U, Taylor-Robinson SD, Njie R, Mishiro S, Thursz MR, Lemoine M. Hepatitis E virus infection and acute-on-chronic liver failure in West Africa: a case-control study from The Gambia. Aliment Pharmacol Ther 2016; 43:375-84. [PMID: 26623967 DOI: 10.1111/apt.13484] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/17/2015] [Accepted: 11/04/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND In sub-Saharan Africa, it is unknown whether hepatitis E virus (HEV) infection is a common precipitating event of acute-on-chronic liver failure (ACLF). AIMS To estimate the prevalence of HEV infection in general population and assess whether HEV is a common trigger of ACLF in cirrhotic patients in The Gambia, West Africa. METHODS We first conducted an HEV sero-survey in healthy volunteers. We then tested cirrhotic patients with ACLF (cases) and compensated cirrhosis (controls) for anti-HEV IgG as a marker of exposure to HEV, and anti-HEV IgA and HEV RNA as a marker of recent infection. We also described the characteristics and survival of the ACLF cases and controls. RESULTS In the healthy volunteers (n = 204), 13.7% (95% CI: 9.6-19.2) were positive for anti-HEV IgG, and none had positive HEV viraemia. After adjusting for age and sex, the following were associated with positive anti-HEV IgG: being a Christian, a farmer, drinking water from wells, handling pigs and eating pork. In 40 cases (median age: 45 years, 72.5% male) and 71 controls (39 years, 74.6% male), ≥70% were infected with hepatitis B virus. Although hepatitis B flare and sepsis were important precipitating events of ACLF, none had marker of acute HEV. ACLF cases had high (70.0%) 28-day mortality. CONCLUSIONS Hepatitis E virus infection is endemic in The Gambia, where both faecal-oral route (contaminated water) and zoonotic transmission (pigs/pork meat) may be important. However, acute HEV was not a common cause of acute-on-chronic liver failure in The Gambia.
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Affiliation(s)
- Y Shimakawa
- MRC Unit The Gambia, Banjul, The Gambia.,Unité d'Épidémiologie des Maladies Émergentes, Institut Pasteur, Paris, France
| | - H F Njai
- MRC Unit The Gambia, Banjul, The Gambia
| | - K Takahashi
- Department of Medical Sciences, Toshiba General Hospital, Tokyo, Japan
| | - L Berg
- MRC Unit The Gambia, Banjul, The Gambia.,Hepatology Unit, Department of Medicine, Imperial College London, London, UK
| | - G Ndow
- MRC Unit The Gambia, Banjul, The Gambia.,Hepatology Unit, Department of Medicine, Imperial College London, London, UK
| | | | - A Ceesay
- MRC Unit The Gambia, Banjul, The Gambia
| | - S Tamba
- MRC Unit The Gambia, Banjul, The Gambia
| | - E Opoku
- MRC Unit The Gambia, Banjul, The Gambia.,Hepatology Unit, Department of Medicine, Imperial College London, London, UK
| | - M Taal
- Ministry of Health and Social Welfare, Banjul, The Gambia
| | - S M F Akbar
- Department of Medical Sciences, Toshiba General Hospital, Tokyo, Japan
| | - M Arai
- Department of Medical Sciences, Toshiba General Hospital, Tokyo, Japan
| | | | - S D Taylor-Robinson
- Hepatology Unit, Department of Medicine, Imperial College London, London, UK
| | - R Njie
- MRC Unit The Gambia, Banjul, The Gambia.,The Gambia Hepatitis Intervention Study, IARC, c/o MRC Unit, Banjul, The Gambia
| | - S Mishiro
- Department of Medical Sciences, Toshiba General Hospital, Tokyo, Japan
| | - M R Thursz
- Hepatology Unit, Department of Medicine, Imperial College London, London, UK
| | - M Lemoine
- MRC Unit The Gambia, Banjul, The Gambia.,Hepatology Unit, Department of Medicine, Imperial College London, London, UK
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7
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Njai H, Shimakawa Y, Ferguson L, Sanneh B, Dalessandro U, Mendy M, Thursz M, Njie R, Lemoine M. Validation of hepatitis B surface antigen (HBsAg) rapid test to screen HBV infection in rural Gambia. Int J Infect Dis 2014. [DOI: 10.1016/j.ijid.2014.03.984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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8
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Lemoine M, Shimakawa Y, Nayagam S, Njie R, Thursz M. Commentary: how long does one need to fast before a Fibroscan examination? Authors' reply. Aliment Pharmacol Ther 2014; 39:541-2. [PMID: 24494840 DOI: 10.1111/apt.12623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Accepted: 12/28/2013] [Indexed: 12/08/2022]
Affiliation(s)
- M Lemoine
- Medical Research Council, The Gambia Unit, Disease Control and Elimination theme, Liver Unit, Fajara, The Gambia; Department of Hepatology, Imperial College London, St Mary's Hospital, London, UK.
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9
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Lemoine M, Shimakawa Y, Njie R, Njai HF, Nayagam S, Khalil M, Goldin R, Ingiliz P, Taal M, Nyan O, Corrah T, D'Alessandro U, Thursz M. Food intake increases liver stiffness measurements and hampers reliable values in patients with chronic hepatitis B and healthy controls: the PROLIFICA experience in The Gambia. Aliment Pharmacol Ther 2014; 39:188-96. [PMID: 24308698 DOI: 10.1111/apt.12561] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 09/02/2013] [Accepted: 11/03/2013] [Indexed: 12/16/2022]
Abstract
BACKGROUND By increasing the hepatic blood circulation, food intake has been suggested to increase liver stiffness measurement (LSM) values in HCV-infected patients. AIM To investigate prospectively the effects of food intake on LSM in hepatitis B virus (HBV)-infected patients and healthy controls. METHODS In The Gambia, patients included in the PROLIFICA project are screened for HBV at the community level and then invited for fasting assessment including LSM. Between April 2012 and October 2012, each day, the first five participants were invited to participate in this study. After the initial examination, a standardised 850 Kcal breakfast was provided. Effect of food intake was assessed by examining mean difference of LSM, IQR and IQR/LSM at T0 (fasting LSM1), T30min (LSM2) and T120min (LSM3) respectively. RESULTS A total of 209 subjects were enrolled in this study (133 were HBV positive, 76 healthy controls). Unreliable measurements occurred more frequently after food intake (5%, 24% and 18% at T0, T30min and T120min respectively). In both groups, median LSM2 was significantly higher than LSM1 [6.2 (IQR: 5.4, 7.9)] vs. 4.9 (4.2, 6.2), P < 0.0001. LSM3 was still higher than the baseline, but lower than LSM2. In multivariable analysis, no factor modified the effect of breakfast on LSM. In a subgroup of patients having liver biopsies, we confirmed that food intake can overestimate liver fibrosis. CONCLUSIONS Food intake significantly increases liver stiffness measurement and its IQR values in patients with chronic hepatitis B as well as healthy individuals; and also the number of unreliable liver stiffness measurement values.
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Affiliation(s)
- M Lemoine
- Medical Research Council, The Gambia Unit, Disease Control and Elimination theme, Liver Unit, Fajara, The Gambia, West-Africa; Department of Hepatology, Imperial College London, St Marys, Norfolk Place, London, UK
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10
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Shimakawa Y. A-site ordered perovskite-structure oxides with functional properties. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311095572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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11
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Matsuda M, Azuma M, Tokunaga M, Shimakawa Y, Kumada N. Disordered ground state and magnetic field-induced long-range order in an S=3/2 antiferromagnetic honeycomb lattice compound Bi3Mn4O12(NO3). Phys Rev Lett 2010; 105:187201. [PMID: 21231130 DOI: 10.1103/physrevlett.105.187201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Indexed: 05/30/2023]
Abstract
Bi3Mn4O12(NO3), in which the Mn4+ ions carry S=3/2, is the first honeycomb lattice system that shows no long-range magnetic order. Using neutron scattering, we have determined that short-range antiferromagnetic correlations develop at low temperatures. Applied magnetic fields induce a magnetic transition, in which the short-range order abruptly expands into a long-range order.
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Affiliation(s)
- M Matsuda
- Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195, Japan
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12
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Abstract
Structural observation of layered double perovskite oxide La(2)CuSnO(6) thin films grown epitaxially on SrTiO(3) is reported by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Particularly the transition layer at the interface was observed, and the first B site layer at the interface was found to be almost formed by the Cu atomic layer as the random structure, followed by formation of the layered structure. In addition, HAADF-STEM images indicate that the thin film is not single crystalline, but some irregular structures were observed to grow around the interface near atomic steps of the substrate of SrTiO(3). Therefore, the steps largely affect the growth process of the thin film.
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Affiliation(s)
- M Haruta
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
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13
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Abstract
The a <100> edge dislocation core formed in an epitaxial BaTiO(3) (BTO) thin film grown on a substrate was investigated by scanning transmission electron microscopy combined with electron energy-loss spectroscopy. Elemental analysis using core-loss spectrum indicates that the atomic ratios of O/Ti and Ba/Ti are decreased at the dislocation core. The near-edge fine structure of the oxygen K-edge recorded from the dislocation core differs slightly from that of relaxed BTO region, which suggests that Ba-O bonding is decreased at the dislocation core. The structure of the dislocation core is discussed using a high-angle annular dark-field image and the electron energy-loss spectroscopy results.
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Affiliation(s)
- H Kurata
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
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14
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Mizumaki M, Saito T, Shiraki H, Shimakawa Y. Orbital Hybridization and Magnetic Coupling of the A-Site Cu Spins in CaCu3B4O12 (B = Ti, Ge, and Sn) Perovskites. Inorg Chem 2009; 48:3499-501. [DOI: 10.1021/ic802166b] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Mizumaki
- Japan Synchrotron Radiation Research Institute (JASRI), Sayo-cho Sayo-gun, Hyogo 679-5198, Japan, and Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - T. Saito
- Japan Synchrotron Radiation Research Institute (JASRI), Sayo-cho Sayo-gun, Hyogo 679-5198, Japan, and Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - H. Shiraki
- Japan Synchrotron Radiation Research Institute (JASRI), Sayo-cho Sayo-gun, Hyogo 679-5198, Japan, and Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Y. Shimakawa
- Japan Synchrotron Radiation Research Institute (JASRI), Sayo-cho Sayo-gun, Hyogo 679-5198, Japan, and Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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Haruta M, Kurata H, Komatsu H, Shimakawa Y, Isoda S. Effects of electron channeling in HAADF-STEM intensity in La2CuSnO6. Ultramicroscopy 2009; 109:361-7. [DOI: 10.1016/j.ultramic.2009.01.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2008] [Revised: 12/01/2008] [Accepted: 01/06/2009] [Indexed: 11/28/2022]
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Prasankumar RP, Okamura H, Imai H, Shimakawa Y, Kubo Y, Trugman SA, Taylor AJ, Averitt RD. Coupled charge-spin dynamics of the magnetoresistive pyrochlore TI2Mn2O7 probed using ultrafast midinfrared spectroscopy. Phys Rev Lett 2005; 95:267404. [PMID: 16486404 DOI: 10.1103/physrevlett.95.267404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Revised: 10/05/2005] [Indexed: 05/06/2023]
Abstract
Optical-pump midinfrared probe spectroscopy is used to investigate coupled charge-spin dynamics in the magnetoresistive pyrochlore TI(2)Mn(2)O(7). We find that the temporal persistence of the photoexcited carrier density is strongly influenced by spin disorder above and below the ferromagnetic Curie temperature. Our results are consistent with a picture whereby spin disorder leads to spatial segregation of the initially excited Tl 6s-O 2p electron-hole pairs, effectively reducing the probability for recombination. This further implies that colossal magnetoresistance in these materials may be driven primarily by Mn t(2g) spin disorder.
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Tsuchiya T, Yoshitake T, Shimakawa Y, Yamaguchi I, Manabe T, Kumagai T, Kubo Y, Mizuta S. Low-temperature growth of La0.8Sr0.2MnO3 thin films on LaAlO3 and SrTiO3 substrates by an excimer laser metal organic deposition (ELMOD) process. J Photochem Photobiol A Chem 2004. [DOI: 10.1016/j.jphotochem.2004.04.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
We evaluated the effects of Bifidobacterium breve-fermented soymilk on probiotic function. An administered strain of B. breve strain Yakult was capable of growing in soymilk with no additives as high as 10(9) CFU/ml. During storage of the fermented soymilk at 10 degrees C for 20 days, viable counts of the strain did not change. The growth inhibition of the strain in a bile-containing medium was lessened by the addition of soy protein. In human feeding experiments, the administered B. breve was recovered at a level of over 10(9) CFU/g faeces, accompanied by an increase in the total number of bifidobacteria. These results indicate that fermented soymilk with B. breve strain Yakult could be a novel type of probiotic food.
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Affiliation(s)
- Y Shimakawa
- Yakult Central Institute for Microbiological Research, 1796 Yaho, Kunitachi, Tokyo 186-8650, Japan.
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Kano M, Ishikawa F, Matsubara S, Kikuchi-Hayakawa H, Shimakawa Y. Soymilk products affect ethanol absorption and metabolism in rats during acute and chronic ethanol intake. J Nutr 2002; 132:238-44. [PMID: 11823584 DOI: 10.1093/jn/132.2.238] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In this study we evaluated the effects of soy products on ethanol metabolism during periods of acute and chronic consumption in rats. Gastric ethanol content and blood ethanol and acetaldehyde concentrations were investigated after the oral administration of ethanol (34 mmol/kg) plus soy products such as soymilk (SM) or fermented soymilk (FSM). The gastric ethanol concentration of the FSM group was greater than that of the control group, whereas portal and aortal blood ethanol concentrations of the FSM group were lower than in controls. The aortal acetaldehyde concentration in the FSM group was lower than that of the control group. The direct effect of isoflavones on liver function was investigated by using hepatocytes isolated from untreated rats. Genistein (5 micromol/L) decreased ethanol (P = 0.045) and tended to decrease acetaldehyde (P = 0.10) concentrations in the culture filtrate. Some variables of ethanol metabolism in the liver were investigated after chronic ethanol exposure for 25 d. Rats consumed a 5% ethanol fluid plus the SM diet, the FSM diet or a control diet. Microsomal ethanol oxidizing activity was significantly lower in the FSM group than the control group. Furthermore, cytosolic glutathione S-transferase activity was higher in the SM and FSM groups than in the control group. Acetaldehyde dehydrogenase activity (low K(m)) in the FSM group (P = 0.15), but not in the SM group (P = 0.31), tended to be greater than in the control group. The amount of thiobarbituric acid reacting substances in the liver of the SM and FSM groups tended to be less than that of the control group (P = 0.18 and 0.10, respectively). These results demonstrate that soymilk products inhibit ethanol absorption and enhance ethanol metabolism in rats.
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Affiliation(s)
- M Kano
- Yakult Central Institute for Microbiological Research, Yaho 1796, Kunitachi, Tokyo 186-8650, Japan.
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Zheng G, Ozaki H, Clark WG, Kitaoka Y, Kuhns P, Reyes AP, Moulton WG, Kondo T, Shimakawa Y, Kubo Y. Superconducting fluctuations and the pseudogap in the slightly overdoped high- T(c) superconductor TlSr2CaCu2O6.8: high magnetic field NMR studies. Phys Rev Lett 2000; 85:405-408. [PMID: 10991294 DOI: 10.1103/physrevlett.85.405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2000] [Indexed: 05/23/2023]
Abstract
From measurements of the 63Cu Knight shift ( K) and the nuclear spin-lattice relaxation rate ( 1/T1) under magnetic fields from zero up to 28 T in the slightly overdoped high- T(c) superconductor TlSr2CaCu2O6.8 ( T(c) = 68 K), we find that the pseudogap behavior, i.e., the reductions of 1/T1T and K above T(c) from the values expected from the normal state at high T, is strongly field dependent and follows a scaling relation. We show that this scaling is consistent with the effects of the Cooper pair density fluctuations. The present finding contrasts sharply with the pseudogap property reported previously in the underdoped regime where no field effect was seen up to 23.2 T. The implications are discussed.
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Affiliation(s)
- Gq Zheng
- Department of Physical Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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Kikuchi-Hayakawa H, Onodera N, Matsubara S, Yasuda E, Shimakawa Y, Ishikawa F. Effects of soya milk and Bifidobacterium-fermented soya milk on plasma and liver lipids, and faecal steroids in hamsters fed on a cholesterol-free or cholesterol-enriched diet. Br J Nutr 1998; 79:97-105. [PMID: 9505807 DOI: 10.1079/bjn19980013] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The effects of freeze-dried soya milk (SM) and Bifidobacterium-fermented soya milk (FSM) on plasma and liver lipids, and faecal steroid excretion were estimated in hamsters fed on a cholesterol-free or cholesterol-enriched diet. Hamsters fed on the cholesterol-free diet containing 300 g FSM/kg had lower levels of plasma VLDL + LDL cholesterol than the animals fed on the control diet. SM in the diet produced a similar pattern without significant differences. In the cholesterol-enriched diet group, SM and FSM decreased the levels of plasma total cholesterol and VLDL + LDL-cholesterol. SM and FSM decreased the plasma triacylglycerol level in both the cholesterol-free and -enriched diet groups. The liver total cholesterol contents in the SM and FSM groups were lower than that in the control group, for hamsters fed on the cholesterol-free diet. The liver triacylglycerol content was not modified by SM or FSM in hamsters fed on either the cholesterol-free or -enriched diet. SM and FSM increased the total bile acid excretion and the proportion of cholesterol entering the cholic acid biosynthesis pathway in both the cholesterol-free and -enriched diet groups. SM and FSM did not affect neutral steroid excretion in the cholesterol-free or -enriched diet group. There was an inverse relationship between VLDL + LDL-cholesterol and faecal bile acid excretion in hamsters fed on the cholesterol-free (r -0.670, P < 0.01) and cholesterol-enriched (r -0.761, P < 0.001) diets respectively. These results indicated that SM had an anti-atherogenic effect, and that this effect was not diminished by prior fermentation.
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Magishi K, Kitaoka Y, Zheng G, Asayama K, Kondo T, Shimakawa Y, Manako T, Kubo Y. Magnetic excitation and superconductivity in overdoped TlSr2CaCu2O7- delta : A 63Cu NMR study. Phys Rev B Condens Matter 1996; 54:10131-10142. [PMID: 9984753 DOI: 10.1103/physrevb.54.10131] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Magishi K, Kitaoka Y, Zheng G, Asayama K, Kondo T, Shimakawa Y, Manako T, Kubo Y. Spin-gap behavior in underdoped TlSr2(Lu0.7Ca0.3)Cu2Oy: 63Cu and 205Tl NMR studies. Phys Rev B Condens Matter 1996; 54:3070-3073. [PMID: 9986203 DOI: 10.1103/physrevb.54.3070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Sushko YV, Kubo Y, Shimakawa Y, Manako T. Pressure effect on the GMR material Tl2Mn2O7 with the pyrochlore structure. ACTA ACUST UNITED AC 1996. [DOI: 10.1007/bf02570993] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Shaked H, Shimakawa Y, Hunter BA, Hitterman RL, Jorgensen JD, Han PD, Payne DA. Superconductivity in the Sr-Ca-Cu-O system and the phase with infinite-layer structure. Phys Rev B Condens Matter 1995; 51:11784-11790. [PMID: 9977919 DOI: 10.1103/physrevb.51.11784] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Shimakawa Y, Jorgensen JD, Shaked H, Hitterman RL, Kondo T, Manako T, Kubo Y. Underdoped, optimally doped, and overdoped superconductors TlSr2(R1-xCax)Cu2O7- delta (R=Lu or Tl). Phys Rev B Condens Matter 1995; 51:568-575. [PMID: 9977120 DOI: 10.1103/physrevb.51.568] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Shimakawa Y, Jorgensen JD, Manako T, Kubo Y. Overdoped metals in the Tl2Ba2CuO6+ delta and TlSr2CaCu2O7- delta systems. Phys Rev B Condens Matter 1994; 50:16033-16039. [PMID: 9975974 DOI: 10.1103/physrevb.50.16033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Shimakawa Y, Jorgensen JD, Hinks DG, Shaked H, Hitterman RL, Izumi F, Kawashima T, Takayama-Muromachi E, Kamiyama T. Crystal structure of (Cu,C)Ba2Ca3Cu4O11+ delta (Tc=117 K) by neutron-powder-diffraction analysis. Phys Rev B Condens Matter 1994; 50:16008-16014. [PMID: 9975970 DOI: 10.1103/physrevb.50.16008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Shaked H, Shimakawa Y, Hunter BA, Radaelli PG, Dabrowski B, Hitterman RL, Jorgensen JD, Han PD, Payne DA, Kikkawa S, Er G, Kanamaru F. Structural effects of hydrostatic pressure in Sr1-xMxCuO2 (M=La,Ca) and Sr4Cu6O10. Phys Rev B Condens Matter 1994; 50:12752-12759. [PMID: 9975441 DOI: 10.1103/physrevb.50.12752] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kondo T, Kubo Y, Shimakawa Y, Manako T. Normal-state magnetic susceptibility in TlSr2(Lu1-xCax)Cu2Oy from the underdoped to the overdoped regime. Phys Rev B Condens Matter 1994; 50:1244-1252. [PMID: 9975796 DOI: 10.1103/physrevb.50.1244] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Uemura YJ, Keren A, Le LP, Luke GM, Wu WD, Kubo Y, Manako T, Shimakawa Y, Subramanian M, Cobb JL, Markert JT. Magnetic-field penetration depth in TI2Ba2CuO6+δ in the overdoped regime. Nature 1993. [DOI: 10.1038/364605a0] [Citation(s) in RCA: 195] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Manako T, Kubo Y, Shimakawa Y. Transport and structural study of Tl2Ba2CuO6+ delta single crystals prepared by the KCl flux method. Phys Rev B Condens Matter 1992; 46:11019-11024. [PMID: 10002965 DOI: 10.1103/physrevb.46.11019] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kubo Y, Kondo T, Shimakawa Y, Manako T, Igarashi H. Superconductor-to-metal transition caused by oxygen nonstoichiometry in TlSr2CaCu2O7- delta having a Cu-O pyramidal layer. Phys Rev B Condens Matter 1992; 45:5553-5557. [PMID: 10000273 DOI: 10.1103/physrevb.45.5553] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ebbesen TW, Tsai JS, Tanigaki K, Tabuchi J, Shimakawa Y, Kubo Y, Hirosawa I, Mizuki J. Isotope effect on superconductivity in Rb3C60. Nature 1992. [DOI: 10.1038/355620a0] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kubo Y, Shimakawa Y, Manako T, Igarashi H. Transport and magnetic properties of Tl2Ba2CuO6+ delta showing a delta -dependent gradual transition from an 85-K superconductor to a nonsuperconducting metal. Phys Rev B Condens Matter 1991; 43:7875-7882. [PMID: 9996409 DOI: 10.1103/physrevb.43.7875] [Citation(s) in RCA: 235] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Shimakawa Y, Kubo Y, Manako T, Igarashi H, Izumi F, Asano H. Neutron-diffraction study of Tl2Ba2CuO6+ delta with various Tc's from 0 to 73 K. Phys Rev B Condens Matter 1990; 42:10165-10171. [PMID: 9995273 DOI: 10.1103/physrevb.42.10165] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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