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Dive into the research topics where Yukari Okubo is active.

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Featured researches published by Yukari Okubo.


Journal of Dermatological Science | 1998

Peripheral blood monocytes in psoriatic patients overproduce cytokines

Yukari Okubo; Michiyuki Koga

Interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8) production by peripheral monocytes in 15 patients with psoriasis vulgaris and 13 healthy controls were investigated using an enzyme-linked immunosorbent assay. Polymorphonuclear leukocytes, mononuclear leukocytes, monocytes, lymphocytes and serum were isolated and cultured for 1, 12, 24 and 48 h in RPMI 1640 medium without fetal calf serum to release the cytokines. All cytokine levels in serum were very low in both psoriatic patients and the controls. However, a significant increase in the IL-1 alpha levels in the monocyte culture supernatants was observed in the psoriatic patients compared with that of the controls. IL-1 beta and IL-8 levels in the monocyte supernatants were also significantly increased in the psoriatic patients compared with the controls. TNF-alpha levels in the 12-h supernatants of the monocytes increased in some samples from psoriatic patients but not in the 48-h supernatants. Our study confirmed the overproduction of cytokines in the peripheral monocytes of the psoriatic patients and suggest the activation of monocytes in the patients with psoriasis.


Journal of Dermatology | 2007

Molecular analysis of Malassezia microflora in the lesional skin of psoriasis patients.

Misato Amaya; Mami Tajima; Yukari Okubo; Takashi Sugita; Akemi Nishikawa; Ryoji Tsuboi

Systemic and focal infections by microorganisms have been known to induce or exacerbate psoriasis. To investigate the role of Malassezia species in the development of psoriasis, we analyzed the Malassezia microflora in psoriasis patients using a nested polymerase chain reaction (PCR) assay, and compared it with those in atopic dermatitis (AD) patients and healthy subjects. Fungal DNA was directly collected from the lesional and non‐lesional skin of the trunk of 22 psoriasis patients by applying a transparent dressing. The extracted DNA was amplified by using specific primers designed for the PCR in the intergenic spacer or internal transcribed spacer area of the ribosomal RNA. All nine of the Malassezia species were detected at different rates from the 22 psoriasis patients. The overall detection rates in lesional and non‐lesional skin of M. restricta, M. globosa and M. sympodialis were high (96%, 82% and 64%, respectively), whereas the detection rates of the other species were relatively low. However, there was no difference in the rates between lesional and non‐lesional skin areas. The average number of Malassezia species detected in overall sites of the psoriasis patients was 3.7 ± 1.6 species, although this fact showed no correlation with the severity of the symptoms. The number of Malassezia species detected was 4.1 ± 1.9 in the AD patients, and 2.8 ± 0.8 in the healthy subjects, suggesting that the skin microflora of psoriasis patients and AD patients show greater diversity than that of healthy subjects.


Journal of Dermatology | 1997

Relationship between Levels of Soluble Interleukin-2 Receptors and the Types and Activity of Vitiligo

Yoshihide Honda; Yukari Okubo; Michiyuki Koga

Levels of serum‐soluble interleukin‐2 receptors (serum sIL‐2R) are thought to indicate the activation of immunocompetent cells, mainly lymphocytes. Elevated levels of serum sIL‐2R have been observed in various infectious and autoimmune diseases and also after organ transplantation. It has been hypothesized that autoimmune mechanisms are involved in the pathogenesis of vitiligo. Therefore, we studied serum sIL‐2R levels in relation to disease types and activity of vitiligo. We used sera separated from venous blood samples from 12 patients with dermatomally distributed type B vitiligo, 17 patients with non‐dermatomally distributed type A vitiligo during the active stage, 9 patients with type A vitiligo during the inactive stage, and 12 normal control subjects.


Journal of Dermatological Science | 2011

Quantification of activated and total caspase-14 with newly developed ELISA systems in normal and atopic skin

Mami Yamamoto; Yayoi Kamata; Toshii Iida; Hidekazu Fukushima; Junko Nomura; Masuyoshi Saito; Mami Tajima; Yukari Okubo; Takashi Momoi; Ryoji Tsuboi; Toshihiko Hibino

BACKGROUND Activation of caspase-14 occurs during terminal differentiation of keratinocytes and may play a role in filaggrin degradation. Therefore, down-regulation of caspase-14 may lead to impaired barrier function. OBJECTIVE To compare the levels of active and total caspase-14 in healthy subjects in various age groups and in patients with atopic dermatitis (AD), using two enzyme-linked immunoassay (ELISA) systems. METHODS We established four clones of monoclonal antibodies to caspase-14 and used clone 3 as the immobilizing antibody. A cleavage site-directed antibody, h14D146 [4] was used for specific quantification of active caspase-14 in extracts of tape-stripped corneocytes. Total caspase-14 was measured with a commercial antibody, H-99. RESULTS The amount of caspase-14 remained constant (ca. 0.1% of extractable proteins) in healthy males from their twenties to their fifties. Caspase-14 was mostly in active form (71-94%) in these extracts. In contrast, caspase-14 level and active caspase-14 ratio were significantly decreased in females in their fifties and sixties. Contents of free amino acids were decreased in females in their sixties, and transepidermal water loss was increased in females in their forties and sixties. In patients with AD, active caspase-14 was markedly down-regulated compared to age-matched controls in both lesional (7.5%) and non-lesional skin (10.6%). Staining of active caspase-14 was considerably weaker in non-lesional skin and was hardly detectable in lesional skin with parakeratosis. CONCLUSION Our new ELISA systems are effective tools to quantify activation of caspase-14. Our results indicate a role of caspase-14 in epidermal barrier function.


Journal of Dermatology | 2016

Efficacy and safety of secukinumab in patients with generalized pustular psoriasis: A 52-week analysis from phase III open-label multicenter Japanese study.

Shinichi Imafuku; Masaru Honma; Yukari Okubo; Mayumi Komine; Mamitaro Ohtsuki; Akimichi Morita; Noriko Seko; Naoko Kawashima; Saori Ito; Tomohiro Shima; Hidemi Nakagawa

Generalized pustular psoriasis (GPP) is a severe inflammatory skin disease characterized by the presence of sterile pustules covering almost the entire body and systemic symptoms such as fever. Secukinumab, a fully human‐recombinant anti‐interleukin‐17A monoclonal antibody was indicated for psoriasis vulgaris and psoriatic arthritis in Japan but is not yet investigated for GPP. In this phase III, open‐label multicenter single arm study, the efficacy and safety of secukinumab as monotherapy or with co‐medication was evaluated in 12 Japanese patients with GPP. All the patients received secukinumab 150 mg s.c. at baseline, week 1, 2, 3 and 4, and then every 4 weeks. Two non‐responders were up‐titrated to 300 mg. Change in GPP severity from baseline was evaluated by clinical global impression (CGI) categorized as “worsened”, “no change”, “minimally improved”, “much improved” or “very much improved”. Treatment success was achieved by 83.3% (n = 10) of patients at week 16 (primary end‐point) with CGI evaluated as “very much improved” (n = 9) and “much improved” (n = 1). Moreover, the area of erythema with pustules improved as early as week 1 and resolved by week 16 in most of the patients. The improvements were sustained throughout 52 weeks. Over the 52‐week treatment period, secukinumab was well tolerated with no unexpected safety signals. Nasopharyngitis, urticaria, diabetes mellitus and arthralgia were the frequent adverse events reported. The data from this study shows that secukinumab can become one of the potent treatment options for GPP.


Journal of The American Academy of Dermatology | 2010

Rosaceiform dermatitis associated with topical tacrolimus treatment.

Shoko Fujiwara; Yukari Okubo; Ryokichi Irisawa; Ryoji Tsuboi

We describe herein 3 patients who developed rosacea-like dermatitis eruptions while using 0.03% or 0.1% tacrolimus ointment for facial dermatitis. Skin biopsy specimens showed telangiectasia and noncaseating epithelioid granulomatous tissue formation in the papillary to mid dermis. Continuous topical use of immunomodulators such as tacrolimus or pimecrolimus should be regarded as a potential cause of rosaceiform dermatitis, although many cases have not been reported.


Journal of Dermatology | 2002

A Case of Eruptive Collagenoma Localized on the Neck and Shoulders

Misato Amaya; Yukari Okubo; Michiyuki Koga

A 78‐year‐old woman, who had first noticed asymptomatic eruptions on her neck and shoulders eight years earlier, presented with papules and nodules 2 to 20 mm in diameter that had a normal to white hue and were flatly elevated. These lesions were scattered and multiple, some forming confluent plaques. Histopathologically, the epidermis was slightly atrophied, and collagen fibers in the dermis were coarse and proliferated. In addition, the number of elastic fibers was slightly decreased. No complications were evident. Based on these findings, the patient was given a diagnosis of mild eruptive collagenoma, a type of connective tissue nevus according to the classification of Uitto. This case is unique in that onset was at an advanced age and that distribution was localized on the neck and shoulders.


Journal of Dermatology | 2013

Anti-adalimumab and anti-infliximab antibodies developed in psoriasis vulgaris patients reduced the efficacy of biologics: Report of two cases

Yuka Matsumoto; Tatsuo Maeda; Ryoji Tsuboi; Yukari Okubo

Biologics such as tumor necrosis factor (TNF) inhibitors are highly effective for treating severe psoriasis, and an increasing number of patients benefit from them. However, subsidiary subjects have arisen in the course of treatment which may directly impact the continued use of these drugs in a given case. In this article, we report two cases of psoriasis vulgaris refractory to treatment with both adalimumab and infliximab. We measured the serum drug concentration and absorbance value of antidrug antibodies using the sandwich enzyme‐linked immunoassay method. Antibodies to adalimumab and infliximab were detected in both patients. The low drug concentration and adverse clinical response observed corroborated these findings. Dosage and concomitant medication are considered to be important factors influencing the development of antibody formation. Therapeutic drug monitoring and measurement of antidrug antibodies will assist in maintaining a clinical response and in optimizing the response of patients being treated with biological therapies. The use of concomitant immunosuppressive medication should be considered for patients who will be treated with their second TNF inhibitor after having developed antidrug antibodies against their first TNF inhibitor.


Journal of Dermatology | 2000

A Case of Dermatomyositis Associated with Mechanic's Hand

Chiharu Watanabe; Yukari Okubo; Tsunao Oh-i; Michiyuki Koga; Haruo Abe; Kouichirou Tawara; Norioki Tsuboi; Toru Hayashi

A 67‐year‐old man was referred to the Department of Internal Medicine at Tokyo Medical University with interstitial pneumonia in July 1999. He presented with keratotic plaques on both palms and on the ventral and lateral sides of his fingers. Erythematous keratosis was observed on the dosal aspect of his fingers and metatarsophalangeal (MP) joints. Edematous erythema was seen on the patients chest, back, and the extensor surfaces of his arms. Electromyography revealed a myogenic pattern and an increased level of myogenic enzymes was found in the blood. Histological findings of the ventral sides of his fingers showed hyperkeratosis and parakeratosis of the dermal tissue and liquefaction degeneration of the basal layer at the papilla. Based on these findings, the patient was given a diagnosis of dermatomyositis associated with mechanics hand. A systemic examination confirmed interstitial pneumonia and carcinoma of the duodenal papilla. Mechanics hand is a type of dermatitis associated with myopathy first reported by Stahl et al. in patients with collagen disease. We report herein the first documented case of mechanics hand in Asians.


Journal of Dermatology | 2002

Increased Microorganisms DNA Levels in Peripheral Blood Monocytes from Psoriatic Patients Using PCR with Universal Ribosomal RNA Primers

Yukari Okubo; Noriko Oki; Hidemi Takeda; Misato Amaya; Sonoko Ito; Masako Osada; Masako Utsumi; Michiyuki Koga; Hisashi Kawashima

It has long been suspected that systemic and focal infections cause or exacerbate psoriatic lesions. We previously showed that peripheral blood monocytes in psoriatic patients are activated and overproduce inflammatory cytokines. In addition, it has been reported that macrophages activated by ingesting microorganisms release tumor necrosis factor (TNF)‐α and interleukin (IL)‐1β. Therefore we hypothesized that the monocytes in psoriatic patients may be activated by ingesting microorganisms and overproduce inflammatory cytokines. We examined the detection of microorganism DNA in monocytes from 15 patients with psoriasis vulgaris and from 12 healthy controls. DNA was extracted from monocytes, and a polymerase chain reaction (PCR) assay was performed for the detection using universal primers from conserved regions of the bacterial 16S ribosomal RNA gene or the fungal 18S rRNA gene. At the same time, we calculated the psoriasis area and severity index (PASI) scores and analyzed their correlations with the microorganisms DNA levels. The results showed that bacterial 16S DNA levels in monocytes were significantly higher in psoriatic patients than in controls. The fungal 18S DNA levels were also higher in psoriatic patients than in controls, but the differences were not significant. Although the microorganisms DNA levels in monocytes of psoriatic patients were high, there was no correlation between the bacterial DNA levels in monocytes of the psoriatics and PASI scores. Our study suggests that monocytes in psoriatic patients engulf more bacteria than there in controls, causing an activation of monocytes and triggering the formation of new lesions in the initial stages of psoriasis.

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Ryoji Tsuboi

Tokyo Medical University

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Yuka Matsumoto

Tokyo Medical University

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Misato Amaya

Tokyo Medical University

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Namiko Abe

Tokyo Medical University

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Tatsuo Maeda

Tokyo Medical University

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Tomonobu Ito

Tokyo Medical University

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