Research Protocol
 

By Dr. Mohammad Othman
Corresponding Author Dr. Mohammad Othman
School of Reeproductive and Developmental Medicine, University of Liverpool, 84 Bradfield Road - United Kingdom M32 9LE
Submitting Author Dr. Mohammad Othman
OBSTETRICS AND GYNAECOLOGY

Probiotics, Preterm Labour, Clinical Trial, Protocol,

Othman M. ProB Trial: Probiotics and the Prevention of Preterm Labour; A Randomised Controlled Trial Protocol. WebmedCentral OBSTETRICS AND GYNAECOLOGY 2012;3(6):WMC003535
doi: 10.9754/journal.wmc.2012.003535

This is an open-access article distributed under the terms of the Creative Commons Attribution License(CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
No
Submitted on: 28 Jun 2012 01:34:19 AM GMT
Published on: 28 Jun 2012 09:29:00 PM GMT

Background


Preterm birth defined as birth occurring after the gestational age of viability (23 weeks, 500 grams weight) and before 37 completed weeks (259 days) of pregnancy, is one of the most important problems in medicine today. Preterm birth is the single largest cause of mortality and morbidity for newborns. It accounts for 5% to 11% of births in the world but is responsible for 28% of all deaths within 28 days of birth and 50% of childhood neurological disabilities (1, 2).

Infection and preterm birth:
In the last 20 years infection has emerged as an important cause of preterm labour and delivery leading to more than 50% of the all preterm deliveries world-wide (1, 3, 4, 5, 6, 7, 8, 9). In this context, the organisms involved may not be necessarily pathogenic; a change in vaginal flora may be enough to trigger the sequence of events leading to a preterm birth (1, 3, 8, 9, 10, 11, 12, 13). Changes in vaginal flora can increase the risk of adverse pregnancy outcomes through a variety of mechanisms. Metalloproteolytic enzymes and other bioactive microbial products act directly on cervical collagen leading to premature cervical shortening and ripening (6, 11, 14).  Bacterial products can also weaken the fetal membranes and promote preterm premature rupture of the membranes (11). Pathologic microorganisms trigger the innate immune system to produce both prostaglandins E2 and F2a and cytokines such as Tumour Necrosis Factor alpha (TNF-a), Interleukin (IL1b, IL6, IL8) and Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) (4, 6, 15, 16, 17). Prostaglandins are potent stimulator of uterine contractions (16) whilst cytokines may lead to direct fetal tissue damage (e.g. fetal brain or lung) or may orchestrate preterm labour (8, 11).

Vaginal ecosystem:
Lactobacillus species, including Lactobacillus acidophilus, L.fermentum, L. crispatus, and L. jensenii are the dominant bacteria in the normal vaginal flora. Lactobacilli are gram positive, catalase negative, non-sporing rods. They ferment glycogen produced by the vaginal epithelium and this reaction leads to the formation of hydrogen peroxide. The presence of hydrogen peroxide producing strains of Lactobacilli in the vaginal flora is associated with a reduced incidence of abnormal flora including bacterial vaginosis (18, 19, 20, 21).  The incidence of bacterial vaginosis in women without Lactobacilli is reported to be 56% compared with 32% in women colonized by non-hydrogen peroxide producing strains and only 4% in women who have hydrogen peroxide producing strains of Lactobacilli (17). It is postulated that reduced levels of lactobacilli allow the populations of other potentially pathogenic microorganisms to grow and trigger the inflammatory processes outlined above (7, 16, 18, 21, 22).

Probiotics and preterm labour:
Probiotics are defined as live microorganisms which, when administered in an adequate amount, confer a health benefit on the host (7, 18, 23, 24). They stimulate an immunomodulation process that includes the induction of mucus production, macrophage activation by lactobacilli signalling, stimulation of secretory IgA and neutrophils, inhibition of release of inflammatory cytokines, and stimulation of elevated peripheral immunoglobulins. It has also been shown that probiotics may modulate cytokine release resulting in large amounts of IL-10 and low levels of IL-12p70, IL-5 and IL-13 with the main source of IL-10 attributable to CD14+ (25, 26, 27, 28).  Smits 2005 (45) has suggested that the beneficial effects of probiotics in the treatment of inflammatory diseases (such as Crohn’s) may be due to the probiotic cells targeting the C-type lactic DC-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN). Probiotics have been shown to displace and kill pathogens and modulate the immune response by interfering with the inflammatory cascade that leads to preterm labour and delivery (7, 25). The administration of Lactobacilli by mouth or intravaginally, or both have been shown to be safe and effective in reducing or treating urogenital infections in non-pregnant populations (7, 29, 30, 31)

Clinical trials of probiotics in pregnancy:
A Cochrane systematic review (32) was conducted and identified seven randomised clinical trials using probiotics for the prevention of preterm labour in women with bacterial vaginosis. One trial started in February 2005 and was terminated in 2007 because the tightly defined inclusion criteria were making recruitment very slow. Another trial started in 2006 and was terminated in 2009 because of limitation of funding.  One trial with 381women recruited was excluded because there were no data on clinical outcomes in the published article; we tried to contact the author with no response. The second trial was excluded because they used prebiotics not probiotics in the trial. Of the three trials included in the review, one enrolled 24 women after 34 weeks of pregnancy using oral fermented milk as probiotic, while the other study with 64 participants utilised commercially available yoghurt to be used vaginally by women diagnosed with bacterial vaginosis in early pregnancy. Third study enrolled 256 women in Finland. Participants were randomised into two experimental groups and one placebo control group. One of the experimental groups received placebo and dietary counselling while the other experimental group received probiotics (Lactobacillus rhamnosus GG and Bi-fidobacterium lactis Bb12 once daily) from the first trimester of pregnancy to the end of breastfeeding and dietary counselling. Effects on very preterm birth (less than 32 weeks) (risk ratio (RR) 0.65; 95% confidence interval (CI) 0.03 to 15.88) and preterm birth (less than 37 weeks) (RR 3.95; 95% CI 0.36 to 42.91) showed very wide CIs and no effect of statistical significance. The trial reports focused on laboratory evidence of infection (lactobacillus count, type of abnormal vaginal flora, vaginal fluid pH, presence of clue cells in vaginal wet smear, number of leukocytes) rather than clinical signs of infection or preterm labour. Reduction in genital infection was therefore the only prespecified clinical outcome for which the data were available for both studies with pooled results showing 81% reduction in genital infection with the use of probiotics {Risk Ratio (RR) 0.19; 95% Confidence Interval (CI) 0.08, 0.48}. We contacted the authors to provide us with the data on any clinical pregnancy related outcomes, but there were no other data than the published. Clinical pregnancy related outcomes include preterm birth before 28, 34, 37 weeks, preterm labour requiring hospital admission, neonatal mortality and severe morbidity. The preceding outcomes were going to help us to study the impact of probiotics on preterm labour and its complications.

Rationale for further studies of probiotics in preterm labour:
Probiotics have been found to be an effective treatment for Crohn’s disease. In Crohn’s disease, enhanced mucosa permeability may play a pivotal role in causing and perpetuating intestinal inflammation (33). The benefits of probiotics have been attributed to the stabilisation of the intestinal barrier and stimulation of a host response, in particular mucosal IgA secretion (13). This evidence could contribute to the better understanding of pathophysiology of preterm labour because of similarities between the immunobiology of Crohn’s disease and recurrent preterm labour. Crohn’s disease is a chronic inflammatory disorder with features which are similar to those produced by infection with organisms such as mycobacteria. More importantly Marks et al 2006 (34) showed that in patients with Crohn’s disease, trauma to rectum, ileum or skin led to abnormally low neutrophil accumulation and lower production of pro-inflammatory interleukin 8 (34). They concluded that in Crohn's disease, a constitutionally weak immune response predisposes to accumulation of intestinal contents that breach the mucosal barrier of the bowel wall, resulting in granuloma formation and chronic inflammation.  These observations are strikingly similar to our recent findings showing that a lack of cervical macrophages was associated with recurrent preterm labour. We have analysed the observational data on 89 women with a past history of preterm labour and delivery. We found that in a subsequent pregnancy, 19 out of 49 women with a low macrophage count (<5% of cervical epithelial cells expressing CD14 antigen) before 20 weeks gestation, delivered before 35+0 (41%), compared with only 5 out of 40 women (12.5%) who had normal cervical macrophage count (Odds Ratio 4.9, 95%CI 1.5 to 18.7; P 0.0037). Therefore, we hypothesize that stimulation of the cervical host response with probiotics will stimulate cervical and vaginal IgA secretion which, in turn, will increase cervical macrophage count. This process may reduce the risk of preterm labour by inhibiting pathogenic organisms and by improving host defence against ascending infection.

Aims of the study


This is feasibility, ‘proof of principle’ study with the following aims:
1. To confirm the association between pre-randomisation cervical macrophage count and risk of preterm birth
2. To evaluate whether the combination of oral and vaginal probiotics is acceptable intervention for pregnant women with history of preterm birth
3. To assess the feasibility of consenting procedures, randomisation and data collection in this group of women
4. To determine if probiotics can influence the cervical macrophage count
5. To determine if post-probiotic cervical macrophage count is associated with timing of spontaneous delivery.

Methodology


Design: Hospital open label randomised controlled trial.

Method of randomisation:
Women will be randomised to one of the treatment groups using central randomisation service. There are no plans to stratify women by their baseline characteristics.

Participants: 50

Inclusion criteria:
1. Pregnant women between 12-16 weeks gestation
2. Certain gestational age confirmed by ultrasound
3. History of at least one spontaneous previous birth between 14 and 32 completed weeks
4. No pathogenic microorganisms on high vaginal and cervical swabs

Exclusion criteria:
1. History of cervical cerclage or history of cervical weakness as defined by need for elective cervical suture at before 16 gestation
2. Uterine congenital anomalies
3. Fetal congenital anomalies
4. Fetal death
5. Ethanol abuse
6. Drug addiction
7. Younger than 16 years old
8. Planned for antenatal care or delivery elsewhere
9. Regular user of probiotics  (e.g. yogurt) unwilling to stop during the course of the trial

Clinical Protocol:
In the normal routine the booking visit, at 12 to 15+6 weeks all patients with history of previous delivery between 14 and 32 weeks will be assessed in the Preterm Labour Clinic. Visualization of the cervix, HVS, Endocervical swab, Trichomonas Vaginalis swab, Chlamydia swab, Ureaplasma and Mycoplasma swab will be carried out. After the initial assessment, patients will be informed about the trial and information sheet will be given to them. At the next visit between16 weeks and 18 weeks all patients will have trans-vaginal scan and the results of the swabs from the first visit will be reviewed. Patients diagnosed with an infection will be treated and will not be eligible to participate in this trial. Women free from any infection who agree to take part in this trial will be consented, have a vaginal swab taken for cytokines and Cytobrush for leukocytes and will be randomised to either the treatment group or control group. Both the experimental and control group will be managed as shown in Illustration 1.

Intervention:
Women randomised to the treatment arm will receive sufficient vaginal probiotic pessary and oral probiotic tablet to take as described once daily for a period of 6 weeks starting at 16-18 weeks gestation. Women in the control group will be managed as per standard clinical protocol. Any complications in both groups will be managed at the discretion of the attending clinicians.

Consent:
Potentially eligible women will be given written information about the study after initial assessment. Eligibility criteria will be confirmed 1-2 weeks later when written consent form will be obtained.

Maternal outcomes:
1. Neutrophil count (measured by ten fields ×400 magnification using a 10-mm×10-mm graticule Covering an area of 0.0625mm2  from the cervical swabs) at 24 and 28 weeks.
2. Cervical mucus inflammatory cytokines –IL6, IL8, TNF-α at 24 weeks.
3. Cervical mucous and vaginal IgA concentrations at 24 weeks.
4. Gestational age at delivery.
5. Preterm birth before 28 and 34 complete weeks of pregnancy.
6. Threatened preterm labour requiring administration of antenatal steroids and/or tocolysis.
7. Cervical length at 23-24 weeks.
8. Vaginal infection before birth confirmed by microbiological findings.
9. Incidence of chorioamnionitis on placental pathology
10. Maternal morbidity: Obstetric and local symptoms related to study interventions.
11. Assessment of compliance using the compliance diary.
12. Woman’s experiences using the compliance diary.

Neonatal outcomes:
1. Incidence of superficial colonisation with Candida species on admission to the neonatal unit
2. Incidence of superficial colonisation with Candida species one week after admission
3. Incidence of early onset neonatal sepsis (CRP ≥ 10mg/l within 72 hours of birth, ± positive blood cultures)
4. Incidence of invasive Candidal disease
5. Survival to discharge

Blinding:
Given the nature of the intervention (open label medications), it will not be possible to blind clinicians or women when clinical outcomes are assessed (including trans vaginal scan). However, laboratory based outcomes (neutrophil count, cytokines and IgA concentrations) will be assessed blindly and the specimens will be labelled using unique trial identifier only.

Data analysis:
The analysis will be descriptive with the aim of estimating the parameters for sample size calculation in a larger study. Data of patient drop out will not be included in the analysis.

Trial end point:
Trial will end by the birth of the last participating woman

Feasibility/ Sample size:
Normally, the high-risk preterm labour clinic at reputable specialised Hospital accepts 50 new referrals per annum at least who are eligible and that around two third will consent. Therefore, it is expected to recruit 50 women in 18 months and this will be the main target of this feasibility study. Twenty five women in each group will be sufficient to test feasibility and estimate parameters for the main trial.

Safety considerations


Most of the current probiotic strains occur as normal commensal of the mammalian flora or are present in fermented food products already consumed for generations worldwide (Illustration 2). On this basis, the WHO and FAO concluded that probiotics can be generally recognized as safe. However, the organizations also state that probiotics may theoretically be responsible for three types of side effects (1) excessive immune stimulation in susceptible individuals, (2) systemic infections, and (3) deleterious metabolic activities (35). Adverse effects were mainly observed in immunocompromised patients, but vigilance regarding the detection of possible rare cases of infection due to probiotics should be exercised (36, 37, 46). No immunological side effect of any probiotic has been reported in man. However when administered parenterally cell wall components such as peptidoglycans from different gram-positive bacteria, including lactobacilli, can induce side-effects such as fever and arthritis (28, 37). There is no evidence that ingested probiotic pose any risk of infection greater than that associated with commensal strains. In quantitative terms, the existing data suggest that the risk of bacteraemia is one case per million individuals. It is virtually impossible to propose a risk of death because of the common association of infections involving lactobacilli with fatal underlying conditions or the presence of polymicrobial infections. However, the risk is unequivocally in the “negligible” range (38, 39, 47) Immunocompromised patients generally are more vulnerable to infection with pathogens and have a higher incidence of opportunistic infections. However, there is no published evidence that consumption of probiotics increases the risk of opportunistic infection among such individuals (28, 38, 40, 47). In addition, 2 clinical studies have been conducted to assess the safety of probiotics in small groups of specific immunocompromised patients (e.g. patients with HIV infection), and the findings of these studies support the safety of probiotics consumed by such groups (41, 42). The risk of probiotic lactobacilli passage in blood, eventually by translocation, is important to determine. Bacterial translocation is defined as the passage of microorganisms from the gastrointestinal to extra-intestinal sites such as the mesenteric lymph nodes, liver, spleen and bloodstream. Indigenous bacteria are continuously translocating in low numbers but are rapidly killed in the lymphoid organs. Bacterial translocation is a major cause of severe infection in immunosuppressed, trauma and post-surgical patients. This may result from three mechanisms: intestinal bacterial overgrowth, increased permeability or damage of the intestinal mucosal barrier, and immunodeficiency (43, 44, 47). Rare cases of infection, including septicaemia and endocarditis caused by lactobacilli, bifidobacteria or other lactic acid bacteria have been reported with the incidence of less than 0.002% (38, 44). The survival of ingested probiotics at different levels of the gastrointestinal tract differs between strains. Some strains are rapidly killed in the stomach while others, such as Lactobacillus acidophilus, can pass through the entire gut at very high concentrations. Milk as a vehicle protects probiotics against gastric conditions. Excessive degradation of the intestinal mucus by probiotics may theoretically be detrimental. Some endogenous bacteria, including lactobacilli, and some strains of bacteroides have the ability to degrade mucus. No mucus degradation has been observed in vitro or in gnotobiotic rats to date (36, 37). The only observed metabolic side effect is gastric upset and this still uncommon side effect of oral probiotics with an incidence of 2%(37, 44).

From the above, adverse effects which we will be looking for are:
1. Local side effects
2. Allergy
3. Bacteraemia
4. Septicaemia
5. Endocarditis
6. Gastric upset.

Altering the vaginal flora could impact on the baby by modifying ascending infection or by modifying microbial colonisation of the baby during vaginal delivery. We expect probiotics to protect the baby. However, the predefined neonatal outcomes will also serve as makers of neonatal safety.

References


1. Kiss H, Petricevic L, Husslein P. Prospective randomised controlled trial of an infection-screening programme to reduce the rate of preterm delivery. BMJ 2004; 1136(10):1-5.
2. McGregor JA, French JI. Pathogenesis to treatment: preventing preterm birth mediated by infection. Infectious Diseases in Obstetrics and Gynaecology 1997; 5:106-14.
3. Chaim W, Mazor M, Leiberman JR. The relationship between bacterial vaginosis and preterm birth. Archives of Gynecology and Obstetrics 1997; 257:51-58.
4. Cram LF, Zapata MI, Toy EC, Baker B. Genitourinary infections and their association with preterm labour. American Family Physician 2002; 65(2):241-8.
5. Crowther CA, Thomas N, Middleton P, Chua M, Esposito M. Treating periodontal disease for preventing preterm birth in pregnant women. In: The Cochrane Database of Systematic Reviews, Issue 2, 2005.
6. Klein LL, Gibbs RS. Use of microbial cultures and antibiotics in the prevention of infection-associated preterm birth. American Journal of Obstetrics and Gynecology 2004; 190:1493-502.
7. Reid G, Bocking A. The potential for probiotics to prevent bacterial vaginosis and preterm labour. American Journal of Obstetrics and Gynecology 2003; 189(4):1202-8.
8. Romero R, Espinoza J, Chaiworapongsa T, Kalache K. Infection and prematurity and the role of preventive strategies. Seminars in Neonatology 2002; 7:259-74.
9. Hillier SL, Nugent RP, Eschenbach DA, Krohn MA, Gibb RS, Martin DH, et al. Association between bacterial vaginosis and preterm delivery of a low-birth-weight infant. The Vaginal Infections and Prematurity Study Group.New EnglandJournal of Medicine 1995; 333(26):1737-42.
10. Leitich H, Brunbauer M, Bodner-Adler B, Kaider A, Egarter C, Husslein P. Antibiotic treatment of bacterial vaginosis in pregnancy: a meta-analysis. American Journal of Obstetrics and Gynecology 2003; 188(3):752-8.
11. McGregor JA, French JI. Pathogenesis to treatment: preventing preterm birth mediated by infection. Infectious Diseases in Obstetrics and Gynaecology 1997; 5:106-14.
12. Reid G, Bruce AW, Fraser N, Heinemann C, Owen J, Henning B. Oral probiotics can resolve urogenital infections. FEMS Immunology and Medical Microbiology 2001; 30:49-52.
13. Reid G, Jass J,Sebulsky MT, McCormick JK. Potential uses of probiotics in clinical practice. Clinical Microbiology Reviews 2003; 16(4):658-72.
14. Howe L, Wiggins R, Soothill PW, Millar MR, Horner PJ, Coroeld AP. Mucinase and sialidase activity of the vaginal microflora: implications for the pathogenesis of preterm labour. International Journal of STD & AIDS 1999; 10:442-7.
15. Reid G. Probiotics for urogenital health. Nutrition in Clinical Care 2002; 5(1):3-8.
16. Riggs MA, Klebanoff MA. Treatment of vaginal infections to prevent preterm birth: a meta-analysis. Clinical Obstetrics and Gynaecology 2004; 47(4):796-807.
17. Ugwumadu AHN, Hay P. Bacterial vaginosis: sequelae and management. Current Opinion in Infectious Diseases 1999; 12(1):53-9.
18. Andreu A. Lactobacillus as a probiotic for preventing urogenital infections. Reviews in Medical Microbiology 2004; 15:1-6.
19. Reid G, Burton J. Use of lactobacillus to prevent infection by pathogenic bacteria. Microbes and Infection 2002; 4:319-24.
20. Reid G, Charbonneau D, Erb J, Kochanowski B, Beuerman D, Poehner R, et al. Fermentum      RC-14 significantly alters vaginal flora. FEMS Immunology and Medical   Microbiology 2003; 35:131-4.
21. Sieber R,Dietz UT.Lactobacillus acidophilus and yogurt in the prevention and therapy of bacterial vaginosis. International Dairy Journal 1998; 8:599-607
22. Wilks M, Wiggins R, Whiley A, Hennessy E, Warwick S, Porter H,et al. Identification and H2O2 production of vaginal lactobacilli from pregnant women at high risk of preterm birth and relation with outcome. Journal of Clinical Microbiology 2004; 42(2):713-7.
23. Elmer GW. Probiotics: Living drugs. American Journal of Health-Systematic Pharmacology 2001; 58:1101-9.
24. Reid G, Charbonneau D, Erb J, Kochanowski B, Beuerman D, Poehner R, et al. Fermentum RC-14 significantly alters vaginal flora. FEMS Immunology and Medical Microbiology 2003; 35:131-4.
25. Bengmark S. Pre-, pro- and synbiotics. Current Opinion in Clinical Nutrition and Metabolic Care 2001; 4:571-9.
26. Mombelli B, Gismondo MR. The use of probiotics in medical practice. International Journal of Antimicrobial Agents. 2000; 16: 531–6.
27. Niers LEM, Timmerman HM, Rijkers GT, van Bleek GM, van Uden NOP, Knol EF,      Kapsenberg ML, Kimpen JLL, Hoekstra MO. Identification of strong interleukin-10 inducing lactic acid bacteria which down-regulate T helper type 2 cytokines. Clinical Expert in Allergy 2005, 35: 1481 – 1489
28. Senok AC, Ismaeel AY, Botta GA. Probiotics: facts and myths. Clinical Microbial Infection. 2005; 11: 958–66.
29. Reid G,BurtonJ, Devillard E. The rationale for probiotics in female urogenital healthcare. Medscape General Medicine 2004; 6(1): 49-72.
30. Marelli G, Papaleo E, Ferrari A. Lactobacilli for prevention of urogenital infections: a review. European Revision of Medical Pharmacological Science 2004; 8: 87-95.
31. Falagas ME, Betsi GI, Tokas T, Athanasiou S. Probiotics for the prevention of  recurrent urinary tract infections in women: a review of the evidence from microbiological and clinical studies Drugs 2006; 66: 1253-61
32. Othman M, Alfirevic Z, Neilson JP. Probiotics for preventing preterm labour. The Cochrane Database of Systematic Reviews 2012, Issue 2.
33. Prantera C. Probiotics for Crohn’s disease: what have we learned? Gut 2006; 55: 757-759
34. Marks DJ, Harbord MW, MacAllister R, Rahman FZ, Young J, Al-Lazikani B, Lees W, Novelli M, Bloomy S, Segal AW. Defective acute inflammation in Crohn’s disease: a clinical investigation. Lancet 2006;367(9511): 668-678.
35. FAO⁄WHO. Evaluation of health and nutritional properties of powder milk and live lactic acid bacteria.Cordoba,Argentina: Food and Agriculture Organization of the United Nations and World Health Organization Expert Consultation Report, 2001; 1–34.
36. Hoesl CE, Altwein JE. The probiotic approach: an alternative treatment option in urology. European Urology. 2005; 47: 288–96.
37. Salminen S, Wright AV, Morelli L, Marteau P, Brassart D, Vos WM, Fonde´ng R, Saxelinh M, Collinsi K, Mogensenj G, Birkelandk SE, Mattila-Sandholmb T. Demonstration of safety of probiotics. International Journal of Food Microbiology. 1998; 44: 93–106.
38. Borriello SP, Hammes WP, Holzapfel W, Marteau P, Schrezenmeir J, Vaara M, Valtonen V. Safety of Probiotics That Contain Lactobacilli or Bifidobacteria. Clinical Infectious Diseases 2003; 36:775–80.
39. Reid G. Safe and efficacious probiotics: what are they? TRENDS in Microbiology. 2006; 30(10): 406-10.
40. Ezendam J, Loveren HV. Probiotics immunomodulation and evaluation of safety and    efficacy. Nutrition Reviews. 2006; 64(1): 1-14.
41. Cunningham-Rundles S, Ahrne S, Bengmark S. Probiotics and immune response. American Journal of Gastroenterology. 2000; 95:S22–5.
42. Wolf BW, Wheeler KB, Ataya DG, Garleb KA. Safety and tolerance of Lactobacillus reuteri supplementation to a population infected with the human immunodeficiency virus. Food      Chemical Toxicology 1998; 36: 1085–94.
43. Boyle RJ, Robins-Browne RM, Tang MLK. Probiotic use in clinical practice: what are the risks? American Journal of Clinical Nutrition. 2006; 83:1256–64.
44. Marteau P, Shanahan F. Basic aspects and pharmacology of probiotics: an overview of pharmacokinetics, mechanisms of action and side effects. Best Practice & Research Clinical Gastroenterology. 2003; 17(5): 725-40.
45. Smits HH,Engering A, van der Kleij D, de Jong EC, Schipper K, van Capel TMM, Zaat  BAJ, Yazdanbakhsh M, Wierenga EA, van Kooyk Y, Kapsenberg ML, Selective probiotic bacteria induce IL-10 producing regulatory T cells in vitro by modulating dendritic cell function through dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin. Journal of Allergy and Clinical Immunology 2005; 115:1260-1267.
46. Hammerman C, Bin-Nun A, Kaplan M. Safety of probiotics: comparison of two      popular strains. BMJ. 2006; 333:1006–8

Source(s) of Funding


None

Competing Interests


None

Disclaimer


This article has been downloaded from WebmedCentral. With our unique author driven post publication peer review, contents posted on this web portal do not undergo any prepublication peer or editorial review. It is completely the responsibility of the authors to ensure not only scientific and ethical standards of the manuscript but also its grammatical accuracy. Authors must ensure that they obtain all the necessary permissions before submitting any information that requires obtaining a consent or approval from a third party. Authors should also ensure not to submit any information which they do not have the copyright of or of which they have transferred the copyrights to a third party.
Contents on WebmedCentral are purely for biomedical researchers and scientists. They are not meant to cater to the needs of an individual patient. The web portal or any content(s) therein is neither designed to support, nor replace, the relationship that exists between a patient/site visitor and his/her physician. Your use of the WebmedCentral site and its contents is entirely at your own risk. We do not take any responsibility for any harm that you may suffer or inflict on a third person by following the contents of this website.

Comments
0 comments posted so far

Please use this functionality to flag objectionable, inappropriate, inaccurate, and offensive content to WebmedCentral Team and the authors.

 

Author Comments
0 comments posted so far

 

What is article Popularity?

Article popularity is calculated by considering the scores: age of the article
Popularity = (P - 1) / (T + 2)^1.5
Where
P : points is the sum of individual scores, which includes article Views, Downloads, Reviews, Comments and their weightage

Scores   Weightage
Views Points X 1
Download Points X 2
Comment Points X 5
Review Points X 10
Points= sum(Views Points + Download Points + Comment Points + Review Points)
T : time since submission in hours.
P is subtracted by 1 to negate submitter's vote.
Age factor is (time since submission in hours plus two) to the power of 1.5.factor.

How Article Quality Works?

For each article Authors/Readers, Reviewers and WMC Editors can review/rate the articles. These ratings are used to determine Feedback Scores.

In most cases, article receive ratings in the range of 0 to 10. We calculate average of all the ratings and consider it as article quality.

Quality=Average(Authors/Readers Ratings + Reviewers Ratings + WMC Editor Ratings)