18 minute read
and reduces inflammation
Sulfated Polysaccharides: Immune Boosters Extracted from Sea Life
A Novel Galactofucan Sulfate Extract Enhances Immunity, Inactivates Viruses Naturally, and Reduces Inflammation
Picture a frozen earth 635 million years ago, and envision the planet at last beginning to thaw from an extraordinary ice age that blanketed land and sea. As the permafrost begins to soften and melt, new life emerges from the ocean depths. It takes the form of sea plants, according to fossil finds discovered by scientists in 2011 in southern China.1
These sea plants were likely the earth’s first “complex” multicellular creatures—a grand harbinger of the flowering of plant and animal life to come. They are the ancestors of the familiar seaweeds of today, with their branches, splayed fans, and ribbony blossoms. And the solutions they have crafted to survive the salty, turbulent seas, at times swarming with microorganisms, offer surprising help for some of our own health challenges.2 It turns out that seaweeds contain large amounts of uniquely structured long-chain sugars, or polysaccharides, with many immune benefits.3 Polysaccharides are chains of single sugar molecules joined together, and include everything from the pectin in apples to glycogen, a form of sugar stored in your liver.4 Seaweed polysaccharides come in a variety of arrangements and molecules, varying by seaweed type, and each appears to have its own set of healing capacities.5
A significant body of seaweed research focuses on fucoidans, sulfated polysaccharides rich in a sugar called fucose. Fucoidans are commonly found in the cell walls of brown macroalgae isolated from Undaria pinnatifida, a large brown kelp native to Japan, and can also be found in other seaweeds such as Fucus vesiculosus (also known as bladderwrack).6,7 Fucoidans are such an important component of seaweeds that they constitute up to 30% of their dry weight.8 Nearly 1500 peer-review studies have been published on fucoidans, and half of those in the last decade alone.9 Interest in fucoidans surged when scientists began to study the world’s longest-living people on the island of Okinawa, some of whom were over a century old.10,11 The Okinawan diet, which includes more than a dozen varieties of seaweed, is now considered one of the healthiest diets in the world.12 Dietary seaweed intake is correlated with lower all-cause mortality.13
Fucoidans have been called “a treasure trove of physiologically active polysaccharides.”8 Their structures are surprisingly diverse, with variable sugar compositions that have different effects on our physiology.12 These include immune modulation,14 antibacterial and antiviral properties,15,16 antiinflammatory ability,17 modulation of gut flora,18 and antithrombotic activity.19,20 Fucoidans enhance immune function and stimulate both innate and adaptive immunity—in other words, they increase both our first line of defense, and our delayed, more specific memory-driven immune response.6 T cells are impacted by fucoidan. T cells have numerous forms, but two significant ones are Th1 cells, which attack intracellular bugs such as bacteria and viruses, and Th2 cells, which fight helminths and other extracellular pathogens. Fucoidans modulate both Th1 and Th2 helper cells.21
Animal studies demonstrate that by stimulating Th1 cells, fucoidan can help eliminate infections such as Leishmania spp., which infects up to 12 million people in 98 different countries around the world.22 In turn, they also downregulate excessive Th2 responses, which can lead to allergies and inflammation. Oral consumption of fucoidans has been shown to relieve pulmonary inflammation in mice,23 while topical application relieves murine dermatitis as well.24
Fucoidans also increase natural killer cell activity, stimulate immune cells called macrophages, and help specialized immune training cells (dendritic cells) to mature.25,26 At doses of 300 mg a day for four weeks, a fucoidan extract stimulated the vaccine response to influenza in 70 volunteers over age 60.27 In this population, fucoidan was shown to increase antibody titers to three strains of the flu. Fucoidans are antiviral, protecting against different types of viral infections.28 They directly inhibit herpes simplex viruses 1 and 2.29 Fucoidans also help protect against potentially deadly viruses, such as hepatitis C30 and a retrovirus known as HTLV-1.31 Fucoidans inhibit the adhesion of hantavirus to cells in vitro.32
Some fucoidans mobilize stem cells and increase their number in the blood.33 Fucoidans might even exert anti-aging activity by increasing the expression of the sirtuins.34 Sirtuins are being studied for their anti-aging potential; it is thought that a boost in sirtuin activity may in part explain how calorie restriction extends life span.35 Finally, fucoidans are potent antiinflammatory molecules.36 Fucoidans may also protect the brain and nervous system from chronic inflammation, particularly via specialized cells called microglia. Thus, fucoidan may, some researchers believe, “offer substantial therapeutic potential for treatment of neurodegenerative diseases.”37
A Novel Aqueous Fucoidan Extract Balances the Immune System
“The role of marine compounds as therapeutic agents has immense potential, and it’s great to be at the cutting edge of this research,” says Stephen Myers, PhD, ND, BMed, of Southern Cross University in New South Wales, Australia. “Fucoidans have immense potential as immunemodulators and anti-inflammatory agents. The research on their benefits is only in its infancy, and we are going to see a wide range of uses for these compounds in future therapeutic applications.”38 New research is emerging on the immune and antiviral benefits of fucoidan isolated from either Undaria
“Fucoidans have immense potential as immune-modulators and anti-inflammatory agents. The research on their benefits is only in its infancy.“ — Stephen Myers, PhD, ND, BMed
pinnatifida seaweed (also known as wakame) or Fucus vesiculosus (also known as bladderwrack). The fucoidan extract is prepared using a novel aqueous extraction process that produces largely unaltered fucoidan fractions with consistent, measurable bioactivity. They yield specific and reproducible benefits in cellular, animal, and clinical studies.
A unique blend of fucoidan and algal polyphenols, along with the nutrients manganese, zinc, and vitamin B6, significantly enhanced immune function in a four-week pilot study of ten healthy adults.39 The study participants were randomly divided into two groups: five received 100 mg daily of the unique blend (containing 75 mg total fucoidan), and five received 1000 mg daily of the unique blend delivered as four 250 mg capsules (containing a total of 750 mg fucoidan). This lower and upper range was used to determine both safety and efficacy. The extract was well tolerated with no clinically relevant changes to measurements of liver or kidney function or to the formation of blood cells.
Changes in immune cells such as T lymphocytes, helper T cells, and cells of the innate immune system were measured at Day 1, Day 3, and Day 28. Numerous measures of immune function significantly improved, including the total number of T cells. There was a continual increase over the 28 days in the activity of innate immune cells called granulocytes and monocytes. These cells attack pathogens as soon as they are encountered. The adaptive immune system responded as well—by Day 3, there were significant increases in killer T cells known as cytotoxic T cells, which recognize infected cells by the presence of antigens on their surface, and then kill them. The researchers conclude that “overall, these data suggest an immune-priming role of the nutrient seaweed complex.” The fucoidan extract was anti-inflammatory as well. Cells in blood samples were “challenged“ with phytohemagglutinin (PHA)-M, a protein that stimulates T cells. After challenge, T cells produced less of an inflammatory molecule called interleukin (IL)-6 on Day 28 as compared to Day 1. Inappropriate levels of IL-6 have been linked to increased cardiovascular risk in the Women’s Health Study—a six-year
study with 619 participants.40 As the researchers note, “any agent capable of reducing IL-6 may confer substantive health benefits.” Finally, it may have the potential for lowering cholesterol, as there was a near-significant beneficial change in blood lipid levels by the end of the four-week study.41 It is notable that this small-scale study did not show a dose response effect in the efficacy outcomes between the two doses of the study preparation. Both doses were effective and well tolerated. However, the researchers point out that a larger study needs to be undertaken to determine dose responsiveness. “This research set out to determine the potential activity of fucoidan and polyphenol rich seaweed extract on immune function,” explains the study’s lead researcher Stephen Myers. “Previous research had demonstrated that fucoidans have real potential as immune modifying agents, and our results have added to these findings.
A unique blend of fucoidan and algal polyphenols … significantly enhanced immune function in a four-week study of ten healthy adults.
You can never state with absolute certainty that we’d get the same result with a pure preparation of Fucus vesiculosus. However, I have little doubt the combination of fucoidan and polyphenols in the preparation tested were the principal active constituents.”38
At the higher dosage, the same combination reduced symptoms of osteoarthritis by over 50% in a 2010 pilot study of 12 individuals.39 The severity of the patients’ average comprehensive arthritis test (COAT) score was measured weekly. This test is comprised of four sub-scales: pain, stiffness, difficulty with physical activity, and overall symptom severity. The COAT score was reduced by 18% with the 100 mg treatment (75 mg fucoidan) and 52% with the 1000 mg dose (750 mg fucoidan) by the end of the study. This preparation also caused a significant increase in total antioxidant capacity, demonstrating potential for antioxidant activity. The algal polyphenols themselves, separate from the fucoidan, are health-promoting, anti-inflammatory, and antioxidant.42 Phlorotannins, polyphenols present in the extract studied, are metabolized and absorbed in the colon and thus are bioavailable.43
Fucoidan may mobilize hematopoietic stem and progenitor cells (HSPC), which are critical for the maintenance and replenishment of blood cells in the bone marrow.44 In mice and nonhuman primates, intravenous (IV) fucoidan has a significant mobilizing effect on HPC.45 In humans, oral intake of fucoidan also mobilizes HPC.33
Fucoidan Inhibits the Activity of Both Bacteria and Viruses
In 2005, the Nobel Prize in Physiology or Medicine was awarded to Barry Marshall and Robin Warren, Marshall’s long-time collaborator, for their discovery of the bacterium Helicobacter pylori and its role in gastritis and peptic ulcer disease.46 H. pylori colonizes the stomach of half the world’s humans, and can cause chronic gastritis, peptic ulcer, gastric cancer, and gastric MALT lymphoma.47 Unfortunately, the efficacy of standard triple antibiotic combination therapy has declined in recent years to only 70%.48,49 Fucoidan may make a clinical difference in that antibiotic efficacy. Three fucoidan aqueous extracts were tested (from Fucus vesiculosus and Undaria pinnatifida), for their ability to inhibit H. pylori from adhering to the stomach lining. When human gastric epithelial cells were tested in vitro, it was found that fucoidans attach to H. pylori, potentially dislodging the bacteria from the gastric cell, or simply preventing it from adhering. In fact, analysis has shown that H. pylori carries several proteins on its outer membrane that bind to fucoidan.50
Just as fucoidan inhibits bacteria from attaching to cells, it can bind to receptors that some viruses use to enter cells, including herpes viruses such as those that cause oral and genital herpes. An extract of 75% pure fucoidan was tested in vitro against 32 clinical strains of herpes simplex virus (HSV), composed of 14 strains of HSV-1 and 18 strains of HSV-2. HSV-1 tends to cause oral herpes lesions, while HSV-2 causes genital herpes lesions.51 Many strains of herpes are now resistant to acyclovir, the most common antiviral drug used to combat infection.
Fucoidan exhibited “excellent in vitro antiviral activity,” the researchers concluded, and was “significantly more active against clinical strains of HSV-2 than HSV-1.”29 This research has been confirmed in animal studies as well; in a 2008 study, oral administration of fucoidan protected mice from infection with HSV-1, as judged from the survival rate and lesion scores.29
Fucoidans offer a remarkable array of bioactivity, ranging for immune modulation to inhibiting infection by bacteria and viruses. This “food” from the sea is truly the ocean’s great medicinal gift.
References
1 Yuan X, Chen Z, Xiao S, et al. An early Ediacaran assemblage of macroscopic and morphologically differentiated eukaryotes. Nature. 2011;470(7334):390-3. PMID: 21331041
2 Percival E. The polysaccharides of green, red and brown seaweeds: their basic structure, biosynthesis and function. Br phycol J. 1979;103-17.
3 Da VD, Viswanathan P. Seaweed polysaccharides - New therapeutic insights against the inflammatory response in diabetic nephropathy Antiinflamm antiallergy agents med chem. 2017;15(3):178-90. PMID: 28215166
4 McGraw-Hill Concise Encyclopedia of Bioscience. Polysaccharide [Internet]. New York: The McGraw-Hill Companies; 2002 [cited 2017 Jul 28]. Available from: http://encyclopedia2.thefreedictionary.com/polysaccharide
5 Ruocco N, Costantini S, Guariniello S, et al. Polysaccharides from the marine environment with pharmacological, cosmeceutical and nutraceutical potential. Molecules. 2016;21(5). PMID: 27128892
6 Fitton J. Therapies from fucoidan; multifunctional marine polymers. Marine Drugs. 2011;9:1731-60. PMID: 22072995
7 Berteau O, Mulloy B. Sulfated fucans, fresh perspectives: structures, functions, and biological properties of sulfated fucans and an overview of enzymes active toward this class of polysaccharide. Glycobiology. 2003;13(6):29-40. PMID: 12626402
8 Kusaykin M, Bakunina I, Sova V, et al. Structure, biological activity, and enzymatic transformation of fucoidans from the brown seaweeds. Biotechnol J. 2008;3(7):904-15. PMID: 18543244
9 Fitton JH, Stringer DN, Karpiniec SS. Therapies from fucoidan: an update. Mar Drugs. 2015;13(9):5920-46. PMID: 4584361
10 Sho H. History and characteristics of Okinawan longevity food. Asia Pac J Clin Nutr. 2001;10(2):159-64. PMID: 11710358
11 Willcox BJ, Willcox DC, Todoriki H, et al. Caloric restriction, the traditional Okinawan diet, and healthy aging: the diet of the world’s longest-lived people and its potential impact on morbidity and life span. Ann N Y Acad Sci. 2007;1114:434-55. PMID: 17986602
12 Willcox D, Willcox BJ, Todoriki H, et al. The Okinawan diet: health implications of a low-calorie, nutrient-dense, antioxidantrich dietary pattern low in glycemic load. J Am Coll Nutr. 2009;28(suppl):500S-516S. PMID: 20234038
13 Iso H, Kubota Y. Nutrition and disease in the Japan Collaborative Cohort Study for Evaluation of Cancer (JACC). Asian Pac J Cancer Prev. 2007;8(suppl):35-80. PMID: 18260705
14 Zapopozhets TS, Besednova NN, Loenko IN. Antibacterial and immunomodulating activity of fucoidan. Antibiot Khimioter. 1995;40(2):9-13. PMID: 7605146
16 Adhikari U, Mateu CG, Chattopadhyay K, et al. Structure and antiviral activity of sulfated fucans from Stoechospermum marginatum. Phytochemistry. 2006;67(22):2474-82. PMID: 17067880
17 Cumashi A, Ushakova NA, Preobrazhenskaya ME, et al. A comparative study of the anti-inflammatory, anticoagulant, antiangiogenic, and anti-adhesive activities of nine different fucoidans from brown seaweeds. Glycobiology. 2007;17:541–52. PMID: 17296677
18 Shang Q, Shan X, Cai C, et al. Dietary fucoidan modulates the gut microbiota in mice by increasing the abundance of Lactobacillus and Ruminococcaceae. Food Funct. 2016;7(7):322432. PMID: 27334000
19 Millet J, Jouault SC, Mauray S, et al. Antithrombotic and anticoagulant activities of a low molecular weight fucoidan by the subcutaneous route. Thromb Haemost. 1999;81:391-5. PMID: 10102467
20 Atashrazm F, Lowenthal RM, Woods GM. Fucoidan and cancer: a multifunctional molecule with anti-tumor potential. Mar Drugs. 2015;13(4):2327-46. PMID: 25874926
21 Kar S, Sharma G, Das PK. Fucoidan cures infection with both antimony-susceptible and -resistant strains of leishmania donovani through Th1 response and macrophage-derived oxidants. J Antimicrob Chemother. 2011;66(3):618-25. PMID: 21393231
22 Barrett MP, Croft SL. Management of trypanosomiasis and leishmaniasis. Br Med Bull. 2012;104:175–96. PMID 23137768
23 Maruyama H, Tamauchi H, Hashimoto M, et al. Suppression of Th2 immune responses by Mekabu fucoidan from Undaria pinnatifida sporophylls. Int Arch Allergy Imm. 2005;137:4, 289-94. PMID: 15970637
24 Yang JH. Topical application of fucoidan improves atopic dermatitis symptoms in NC/Nga mice. Phytother Res. 2012;26(12):1898-903. PMID: 22431003
25 Shimizu J, Wada-Funada U, Mano H, et al. Proportion of murine cytotoxic T cells is increased by high molecular-weight fucoidan extracted from Okinawa mozuku (Cladosiphon okamuranus). J Health Sci. 2005;51(3):394-7. doi: 10.1248/ jhs.51.394
26 Hu Y, Cheng SC, Chan KT, et al. Fucoidan enhances dendritic cell-mediated T-cell cytotoxicity against NY-ESO-1 expressing human cancer cells. Biochem Biophys Res Commun. 2010;392(3):329-34. PMID: 20067767 28 Hayashi K, Nakano T, Hashimoto M, et al. Defensive effects of a fucoidan from brown alga Undaria pinnatifida against herpes simplex virus infection. Int Immunopharmacol. 2008;8(1):109-16. PMID: 18068106
29 Thompson KD, Dragar C. Antiviral activity of Undaria pinnatifida against herpes simplex virus. Phytother Res. 2004;18(7):551-5. PMID: 15305315
30 Mori N, Nakasone K, Tomimori K, et al. Beneficial effects of fucoidan in patients with chronic hepatitis C virus infection. World J Gastroenterol. 2012;18(18):2225-30. PMID: 22611316
31 Araya N, Takahashi K, Sato T, et al. Fucoidan therapy decreases the proviral load in patients with human T-lymphotropic virus type-1-associated neurological disease. Antivir Ther. 2011;16(1):89-98. PMID: 21311112
32 Makarenkova ID, Kompanets GG, Zaporozhets TS. Inhibition of adhesion of the pathogenic microorganism to the eucaryotic cells. J Microbiol. 2006:121-5.
33 Irhimeh MR, Fitton JH, Lowenthal RM, et al. Fucoidan ingestion increases the expression of CXCR4 on human CD34+ cells. Exp Hematol. 2007;35(6):989-94. PMID: 17533053
34 Wang T, Zhu M, He Z. Low-molecular-weight fucoidan attenuates mitochondrial dysfunction and improves neurological outcome after traumatic brain injury in aged mice: involvement of Sirt3. Cell Mol Neurobiol. 2016;36(8):1257-68. PMID: 26743530
35 Guarente L. Sirtuins in aging and disease. Cold Spring Harb Symp Quant Biol. 2007;72:483-8. PMID: 18419308
36 Semenov AV, Mazurov AV, Preobrazhenskaia ME, et al. Sulfated polysaccharides as inhibitors of receptor activity of P-selectin and P-selectin-dependent inflammation. Quest Med Chem. 1998;44(2):135-43. PMID: 9634715
37 Park HY, Han MH, Park C, et al. Anti-inflammatory effects of fucoidan through inhibition of NF-κB, MAPK and Akt activation in lipopolysaccharide induced BV2 microglia cells. Food Chem Toxicol. 2011;49(8):1745-52. PMID: 21570441
38 Personal communication, 2017 Jul 28.
39 Myers SP, O’Connor J, Fitton JH, et al. A combined Phase I and II open-label study on the immunomodulatory effects of seaweed extract nutrient complex. Biologics. 2011;5:45-60. PMID: 21383915 41 Kumar SA, Magnusson M, Ward LC, et al. Seaweed supplements normalise metabolic, cardiovascular and liver responses in high-carbohydrate, high-fat fed rats. Mar Drugs. 2015;13(2):788-805. PMID: 25648511
42 Díaz-Rubio ME, Pérez-Jiménez J, Saura-Calixto F. Dietary fiber and antioxidant capacity in Fucus vesiculosus products. Int J Food Sci Nutr. 2009;60(suppl)2:23-34. PMID: 18951280
43 Corona G, Ji Y, Anegboonlap P, et al. Gastrointestinal modifications and bioavailability of brown seaweed phlorotannins and effects on inflammatory markers. Br J Nutr. 2016;115(7):124053. PMID: 26879487
44 Granick JL, Simon SI, Borjesson DL. Hematopoietic stem and progenitor cells as effectors in innate immunity. Bone Marrow Res. 2012;2012:165107. PMID: 22762001
45 Sweeney EA, Lortat-Jacob H, Priestley GV, et al. Sulfated polysaccharides increase plasma levels of SDF-1 in monkeys and mice: involvement in mobilization of stem/progenitor cells. Blood. 2002;99:44-51. PMID: 11756151
46 Weintraub P. The Dr. who drank infectious broth, gave himself an ulcer, and solved a medical mystery [Internet]. Waukesha (WI): Kalmbach Publishing Co., Discover Magazine; 2010 [cited 2017 Jul 28]. Available from: http://discovermagazine.com/2010/mar/07-drdrank-broth-gave-ulcer-solved-medical-mystery
47 Marshall BJ, Windsor HM. The relation of Helicobacter pylori to gastric adenocarcinoma and lymphoma: pathophysiology,epidemiology, screening, clinical presentation, treatment, and prevention. Med Clin North Am. 2005;89(2):313-44. PMID: 15656929
48 Mégraud F. H pylori antibiotic resistance: prevalence, importance, and advances in testing. Gut. 2004;53(9):1374-84. PMID: 15306603
49 Horiki N, Omata F, Uemura M, et al. Annual change of primary resistance to clarithromycin among helicobacter pylori isolates from 1996 through 2008 in Japan. Helicobacter. 2009;14(5):86-90. PMID: 19751432
50 Chua EG, Verbrugghe P, Perkins TT, et al. Fucoidans disrupt adherence of helicobacter pylori to AGS cells in vitro. Evid Based Complement Alternat Med. 2015;2015:120981. PMID: 26604968
51 WebMD. Herpes simplex: Herpes type 1 and 2 [Internet]. Atlanta (GA): WebMD LLC; [cited 2017 Jul 28]. Available from: http://www.webmd.com/genital-herpes/pain-managementherpes
Continued from p. 7, "New Studies Confirm the Power of Three Chinese Herbs for Asthma"
14 Wen MC, Wei CH, Hu ZQ, et al. Efficacy and tolerability of anti-asthma herbal medicine intervention in adult patients with moderate-severe allergic asthma. J Allergy Clin Immunol. 2005;116(3):517-24. PMID: 16159618
15 Li XM, Huang CK, Zhang TF, et al. The Chinese herbal medicine formula MSSM-002 suppresses allergic airway hyperreactivity and modulates TH1=TH2 responses in a murine model of allergic asthma. J Allergy Clin Immunol. 2000;106:660-8. PMID: 11031336
16 To learn more about Sophora flavescens, see both Bronchial Epilepsy (pp. 5–6) and The Neuroelectric Origins of Asthma (pp. 2–3) in this issue.
17 Note: Although the protocol specified enrollment of 18 individuals in the study (six per dose level), because of an error in randomizing, two additional individuals were recruited in order to complete the experiment while maintaining blinding.
18 Kelly-Pieper K, Patil SP, Busse PJ. Safety and tolerability of an antiasthma herbal Formula (ASHMI) in adult subjects with asthma: a randomized, double-blinded, placebo-controlled, dose-escalation phase I study. Altern Complement Med. 2009;15(7):735-43. PMID: 19586409
19 Zhang T, Srivastava K, Wen MC, et al. Pharmacology and immunological actions of a herbal medicine ASHMI on allergic asthma. Phytother Res. 2010;24:1047-55. PMID: 19998324
20 Busse PJ, Schofield B, Birmingham N, et al. The traditional Chinese herbal formula ASHMI inhibits allergic lung inflammation in antigen-sensitized and antigen-challenged aged mice. Ann Allergy Asthma Immunol. 2010;104:236-46. PMID: 20377113
21 Srivastava K, Sampson HA, Emala CW, et al. The anti-asthma herbal medicine ASHMI acutely inhibits airway smooth muscle contraction via prostaglandin E2 activation of EP2/EP4 receptors. J Physiol Lung Cell Mol Physiol. 2013;305(12):L1002-10. PMID: 24163140
22 Srivastava K, Sampson HA, Li X. The anti-asthma Chinese herbal formula ASHMI provides more persistent benefits than dexamethasone in a murine asthma model. J All Clin Immun. 2011;2(127),p AB261
23 Matsui S, Matsumoto H, Sonoda Y, et al. Glycyrrhizin and related compounds down-regulate production of inflammatory chemokines IL-8 and eotaxin 1 in a human lung fibroblast cell line. Int Immunopharmacol. 2004;4:1633-44. PMID: 15454116
24 Li XM. Treatment of asthma and food allergy with herbal interventions from traditional Chinese medicine. Mount Sinai J Med. 2011;78:697-716. PMID: 21913200
25 Jayaprakasam B, Yang N, Wen MC, et al. Constituents of the anti-asthma herbal formula ASHMI(TM) synergistically inhibit IL-4 and IL-5 secretion by murine Th2 memory cells, and eotaxin by human lung fibroblasts in vitro. J Integr Med. 2013;11(3):195-205. PMID: 23743163
26 Wang YH, Hogan SP. Chinese herbal anti-asthma tea to go! Clin Exp Allergy. 2010;40(11):1590-2. PMID: 21039969
