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Probiotics and Prebiotics in Pediatrics [栄養・食餌]

Probiotics and Prebiotics in Pediatrics

Dan W. Thomas, MD, Frank R. Greer, MD and Committee on Nutrition; Section on Gastroenterology, Hepatology, and Nutrition

This clinical report reviews the currently known health benefits of probiotic and prebiotic products, including those added to commercially available infant formula and other food products for use in children. Probiotics are supplements or foods that contain viable microorganisms that cause alterations of the microflora of the host. Use of probiotics has been shown to be modestly effective in randomized clinical trials (RCTs) in (1) treating acute viral gastroenteritis in healthy children; and (2) preventing antibiotic-associated diarrhea in healthy children. There is some evidence that probiotics prevent necrotizing enterocolitis in very low birth weight infants (birth weight between 1000 and 1500 g), but more studies are needed. The results of RCTs in which probiotics were used to treat childhood Helicobacter pylori gastritis, irritable bowel syndrome, chronic ulcerative colitis, and infantile colic, as well as in preventing childhood atopy, although encouraging, are preliminary and require further confirmation. Probiotics have not been proven to be beneficial in treating or preventing human cancers or in treating children with Crohn disease. There are also safety concerns with the use of probiotics in infants and children who are immunocompromised, chronically debilitated, or seriously ill with indwelling medical devices.

Prebiotics are supplements or foods that contain a nondigestible food ingredient that selectively stimulates the favorable growth and/or activity of indigenous probiotic bacteria. Human milk contains substantial quantities of prebiotics. There is a paucity of RCTs examining prebiotics in children, although there may be some long-term benefit of prebiotics for the prevention of atopic eczema and common infections in healthy infants. Confirmatory well-designed clinical research studies are necessary.

Key Words: probiotics • prebiotics • pediatrics • supplements • nutrition

Abbreviations: LGG = Lactobacillus rhamnosus GG • FOS = fructo-oligosaccharide • IBD = inflammatory bowel disease • RCT = randomized controlled trial • CI = confidence interval • RR = relative risk • OR = odds ratio • NEC = necrotizing enterocolitis • CUC = chronic ulcerative colitis • IBS = irritable bowel syndrome • GOS = galacto-oligosaccharide • FDA = Food and Drug Administration

http://pediatrics.aappublications.org/cgi/content/full/126/4/791



KEY ELEMENTS OF ALLERGIC DISEASES [アレルギー]

KEY ELEMENTS OF ALLERGIC DISEASES

ALLERGENS. The term allergen refers to an antigen that triggers an IgE response in genetically predisposed individuals. Most allergens are proteins that have molecular weights of 10-70 kDa; molecules <I0 kDa do not bridge adjacent IgE antibody molecules on the surface of mast cells or basophils; most molecules >70 kDa do not pass through mucosal surfaces needed to reach
antigen-presenting cells for stimulation of the immune system. Allergens frequently function in their natural state as proteolytic enzymes, which may contribute to increased mucosal permeability
and sensitization. This includes a number of major allergens such as Dermatophagoides pteronyssinus allergen I (Der p 1) from the house dust mite.

T CELLS. All individuals are exposed to potential allergens. Nonatopic subjects respond with the proliferation of T helper type 1 (Th1) cells, which secrete cytokines, including interferon (IFN)-gamma, that are involved in the elicitation of allergen-specific IgG antibodies. Th1 cells are typically involved in the eradication of intracellular organisms such as mycobacteria, because of the ability of Th1 cytokines to activate phagocytes and promote the production of opsonizing and complement-fixing antibodies. Genetically predisposed atopic individuals respond with a brisk expansion of T helper type 2 (Th2) cells that secrete cytokines favoring IgE synthesis and eosinoohilia.
  Atopic responses include the generation of allergen-specific IgE antibodies that are detectable by serum testing or positive immediate reactions to allergen extracts on prick skin testing (see Chapter 140). The Th2 cytokines interleukin (1L)-4 and IL-13 play a key role in immunoglobulin isotype switching to IgE (Fig.139-1). IL-5 and IL-9 further enhance IgE synthesis and play an important role in the differentiation and development of eosinophils. The combination of IL-3, IL-4, and IL-9 contributes to mast cell development. Th2 cytokines play an important role in the pathogenesis of asthma and allergic diseases; Th2 cells infiltrate into the affected tissues of acute allergic tissue reactions. Chronic allergic reactions often are characterized by the infiltration of Th1 and Th2 cells. This is important because Th1-type cytokines such as IFN-gamma can potentiate the function of allergic inflammatory effector cells such as eosinophils and thereby contribute to disease severity.
  A small subset of T cells referred to as T regulatory (Treg) cells are thought to play a critical role in allergic and autoimmune diseases. These cells have the ability to suppress effector T cells of either the Th1 or Th2 phenotypes involved in mediating inflammation in a direct cell-contact or antigen-specific manner. Treg cells express CD4+CD25+ surface molecules and immunosuppressive cytokines such as IL-10 and transforming growth factor (TGF)-beta1. The forkhead/winged-helix transcription factor gene FOXP3 is specifically expressed by CD4+CD25+ Treg cells and programs their development and function. Adoptive transfer of Treg cells inhibits the development of airway eosinophilia and protects against airway hyperreactivity in animal models of asthma. Patients with mutations in the human FOXP3 gene lack CD4+CD25+ Treg cells and develop severe immune dysregulation with polyendocrinopathy and food allergy and high serum IgE levels (XLAAD/IPEX disease) (see Chapter 125). It is thought that CD4+CD25+ Treg cells play an important role in controlling the allergic immune response and the lack of such cells may predispose to the development of allergic diseases.

ANTIGEN-PRESENTING CELLS (APC). Dendritic cells, Langerhans cells, monocytes, and macrophages play an important role in the induction of allergic inflammation by presenting allergens to T cells and by contributing to the local recruitment of effector cells. APCs are a heterogeneous group of cells with the common property of presenting antigens in the context of the major histocompatibility complex (MHC). Dendritic cells and Langerhans cells are unique in their ability to prime nai've T cells and are responsible for the primary immune response, which is the sensitization phase of allergy. APCs are found primarily in lymphoid organs and the skin. Monocytes and macrophages likely play more of a role in activating memory T-cell responses, which occurs during the elicitation phase of allergy.
  Dendritic cells residing in peripheral sites such as the skin, intestinal lamina propria, and lung are relatively immature. These immature dendritic cells take up antigens in tissues and then migrate to the T-cell areas in locally draining lymph nodes. During this migration, they undergo phenotypic and functional changes characterized by increased expression of MHC class I, MHC class II, and co-stimulatory molecules that react with CD28 expressed on T cells. In the lymph nodes, they directly present processed antigens to resting T cells to induce their proliferation and differentiation.
  Based on their ability to favor Th1 or Th2 differentiation, mature dendritic cells have been designated as DC1 or DC2, respectively. The critical factor for the polarizing mechanism to Th1 cells is the level of IL-12 produced by DC1 cells. Differentiation of T cells in the absence of IL-12 production by DC2 leads to Th2 cells. Histamine and PGEz inhibit IL-12 production and contribute to the development of DC2. A unique feature of atopy is the presence of allergen-specific IgE on the cell surface of their APCs. Importantly, the formation of Fc E receptor I (FcERI)/IgE/allergen complexes on the APC cell surface markedly facilitates allergen uptake and allergen presentation. The clinical importance of this phenomenon is supported by the observation that FceRI-positive Langerhans cells bearing IgE molecules is a prerequisite for provocation of eczematous lesions by aeroallergens applied to the skin of patients with atopic dermatitis. The role of the low-affinity IgE receptor Fc E receptor II (FceRII, CD23) on monocyte-macrophages is less clear, although it
appears that under certain conditions it can also facilitate antigen capture. Cross linking of FcERII as well as FceRI on monocyte-macrophages leads to the release of inflammatory mediators.



包莖手術 시켜야 하나? [腎臓・尿路]

包莖手術 시켜야 하나?

出生時 男子 아이는 陰茎 끝을 包皮(foreskin)라는 皮膚가 감싸고 있다. 이 包皮를 除去하는 것이 包茎手術이고 美国에서는 大体로 出生後 며칠 内에 施行된다. 이때 嬰児는 安定되고 健康해야 한다.

科学的으로 包茎手術은 몇가지 利点이 있으나, 이것은 美国小児科学会(AAP)가 모든 嬰児에게 包茎手術을 勧할 만큼 充分치는 않다.

왜냐하면 包茎手術은 아이의 健康에 必須的이지 않으며, 父母는 利益과 危険 사이에서 무엇이 아이에게 最善인지를 決定해야만 한다. 包茎手術은 나이가 들 수록 더 危険할 수 있으므로, 父母는 빨리 決定하는 것이 좋다.

父母들이 包茎手術을 選択하는 理由

父母들이 包茎手術을 選択하는 多様한 理由가 있다:

  • 다음과 같은 医学的 利益
    • 尿路感染(UTI)의 危険度 若干 減少. 包茎手術을 한 아이는 1歳 以前에 大略 1000名中 1名 꼴로 尿路感染이 発生한다. 包茎手術을 하지 않은 아이는 1歳 以前에 大略 100名中 1名 꼴로 尿路感染이 発生한다.
    • 陰莖癌의 危険度를 낮춰준다. 하지만, 陰茎癌은 男性에서 発生頻度가 매우 낮다.
    • 性病(STIs), AIDS의 発生 危険度를 若干 減少시킨다.
    • 包皮感染을 予防한다.
    • Phimosis(包皮가 좁아져서 젖혀지지 않는 것)을 予防한다.
    • 性器 衛生管理가 더 쉽다.
  • 社会的 理由. 많은 父母가 "家族 内의 男子들이 이미 다 했다"라는 理由 또는 아들이 그 속에서 "다르다"고 느끼지 않게 하기 위해.
  • 宗教的 또는 文化的 理由. 유대教와 이슬람教 集団에서 施行.

父母들이 包茎手術을 選択하지 않는 理由

父母들이 包茎手術을 選択하지 않는 理由는 다음과 같다:

  • 危険性에 대한 두려움. 副作用은 드물고 普通 些少한 便이나 出血, 感染, 包皮가 너무 짧게 切断되거나 너무 길게 남는 경우, 그리고 回復이 不適切한 경우 등이 있을 수 있다.
  • 包皮가 必要하다는 믿음. 包皮가 陰茎 끝(亀頭)을 保護해 준다고 느끼는 사람들이 있다. 종종 排尿障碍를 일으켜 手術的 処置가 必要할 수도 있다.
  • 性交에 影響을 줄 수 있다는 믿음. 包茎을 通해 陰茎 끝이 덜 敏感해지고, 成人이 되어 性的 즐거움을 減少시킨다고 느끼는 경우가 있다.
  • 適切한 衛生이 健康威嚇을 減少시킨다는 믿음. 男子아이들은 適切한 衛生教育을 通해 感染이나 陰茎癌, 性病 等이 減少될 수 있다.(包茎手術 안해도 管理만 잘하면 危険 낮다는 意味)
Source
Circumcision: Information for Parents (Copyright © 2007 American Academy of Pediatrics, Updated 6/07)
タグ:包莖手術



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