Use of a specific bacteriophage treatment to reduce Salmonella in poultry products

Bacteriophages represent a group of viruses that specifically infect and replicate in bacteria and could potentially be used to reduce recovery of Salmonella from poultry carcasses. Bacteriophages were isolated from municipal wastewater in the presence of Salmonella enteritidis phage type 13A (SE). In the first 2 experiments, commercially processed broiler carcass rinse water was pooled and divided. The addition of 10(10) pfu/mL of a single bacteriophage (PHL 4) with selected concentrations of SE reduced (P < 0.05) frequency of SE recovered as compared with the control rinse water sample. In experiments 3 and 4, broiler carcasses were intentionally inoculated with SE, sprayed with selected concentrations of PHL 4, and rinsed for SE enrichment and isolation. Application of 5.5 mL of 10(8) or 10(10) pfu/mL of PHL 4 reduced (P < 0.05) the frequency of SE recovery as compared with controls. In experiments 5 and 6, commercially processed turkeys were rinsed with water containing 72 wild-type bacteriophages isolated against SE, which were amplified in SE, or the Salmonella isolated antemortem from drag swabs from the flock selected for in-plant treatment, or a combination of bacteriophages amplified by each bacterial host. All bacteriophage treatments reduced (P < 0.05) frequency of Salmonella recovery as compared with controls. Sufficient concentrations of an appropriate bacteriophage, or a bacteriophage mixture, can significantly reduce recoverable Salmonella from carcass rinses.

In-Line Monitoring of Moisture Content in Fluid Bed Dryers Using Near-IR Spectroscopy with Consideration of Sampling Effects on Method Accuracy

In-line near-IR moisture monitoring of the dynamic, fluid bed drying environment has been reported in recent years by several research groups; however, analytical figures of merit with regard to prediction accuracy are discussed in only a subset of this work, and issues with sampling and sample presentation are scarcely addressed at all. In this study, experiments were performed at 65-, 300-, and 600-L drying scales using several different sampling configurations in an effort to better understand and improve in-line near-IR method accuracy. Findings from this work demonstrate that process heterogeneity plays a major role in determination of apparent prediction accuracy. This aspect is general to all in-line measurements and plays an especially important role in solids and slurry systems that are prone to heterogeneity. In addition to experimental results, simulations based on these findings and sampling theory demonstrate an interesting paradox: depending on the sampling configuration employed, the method with the smallest apparent error is not necessarily optimal for process monitoring and control. Furthermore, sampling configuration influences the number of samples necessary to define an adequate calibration set. Finally, process understanding that was gained as a result of temporally rich, in-line measurements will be presented.

Immunosuppression by the JAK3 Inhibitor CP-690,550 Delays Rejection and Significantly Prolongs Kidney Allograft Survival in Nonhuman Primates

BACKGROUND

Janus kinase 3 (JAK3) mediates signal transduction from cytokine receptors using the common chain (gammac). Because mutations in genes encoding gammac or JAK3 result in immunodeficiency, we investigated the potential of a rationally designed inhibitor of JAK3, CP-690,550, to prevent renal allograft rejection in nonhuman primates.

METHODS

Life-supporting kidney transplantations were performed between mixed leukocyte reaction-mismatched, ABO blood group-matched cynomolgus monkeys. Animals were treated with CP-690,550 (n = 18) or its vehicle (controls, n = 3) and were euthanized at day 90 or earlier if there was allograft rejection.

RESULTS

Mean survival time (+/- standard error of mean) in animals treated with CP-690,550 (53 +/- 7 days) was significantly longer than in control animals (7 +/- 1 days, P=0.0003) and was positively correlated with exposure to the drug (r = 0.79, P < 0.01). Four treated animals were euthanized at 90 days with a normal renal function and low-grade rejection at final pathology. Occurrence of rejection was significantly delayed in treated animals (46 +/- 7 days from transplantation vs. 7 +/- 1 days in controls, P = 0.0003). Persistent anemia, polyoma virus-like nephritis (n = 2), and urinary calcium carbonate accretions (n = 3) were seen in animals with high exposure. Natural killer cell and CD4 and CD8 T-cell numbers were significantly reduced in treated animals. Blood glucose, serum lipid levels, and arterial blood pressure were within normal range in treated animals, and no cancers were demonstrated.

CONCLUSIONS

CP-690,550 is the first reported JAK3 inhibitor combining efficacy and good tolerability in a preclinical model of allotransplantation in nonhuman primates and thus has interesting potential for immunosuppression in humans.

Comparison of near-infrared and laser-induced breakdown spectroscopy for determination of magnesium stearate in pharmaceutical powders and solid dosage forms

Near-infrared (NIR) spectroscopy has become well established in both the pharmaceutical arena and other areas as a useful technique for rapid quantitative analysis of solid materials. Though laser-induced breakdown spectroscopy (LIBS) has not been widely applied in the pharmaceutical industry, the technique has been used for rapid quantitative analysis of solids in many other applications. One analysis amenable to each technique is the determination of magnesium stearate in solids during the lubrication blending unit operation of pharmaceutical processing. A comparative study of the utility of these two techniques for this application will be presented. Necessary sample preparations and the extent and type of matrix effects will be discussed. Additionally, it will be shown that NIR provides better accuracy and precision than LIBS with the experimental parameters used; however, LIBS showed superior selectivity as it was demonstrated to be more robust to sample matrix perturbations. Examples of blending applications will also be presented.

A DNA microarray survey of gene expression in normal human tissues

A systematic survey of gene expression in 115 human tissue samples using cDNA microarrays provides a dataset that can be used as a baseline for comparison with expression in diseased tissue.

Background

Numerous studies have used DNA microarrays to survey gene expression in cancer and other disease states. Comparatively little is known about the genes expressed across the gamut of normal human tissues. Systematic studies of global gene-expression patterns, by linking variation in the expression of specific genes to phenotypic variation in the cells or tissues in which they are expressed, provide clues to the molecular organization of diverse cells and to the potential roles of the genes.

Results

Here we describe a systematic survey of gene expression in 115 human tissue samples representing 35 different tissue types, using cDNA microarrays representing approximately 26,000 different human genes. Unsupervised hierarchical cluster analysis of the gene-expression patterns in these tissues identified clusters of genes with related biological functions and grouped the tissue specimens in a pattern that reflected their anatomic locations, cellular compositions or physiologic functions. In unsupervised and supervised analyses, tissue-specific patterns of gene expression were readily discernable. By comparative hybridization to normal genomic DNA, we were also able to estimate transcript abundances for expressed genes.

Conclusions

Our dataset provides a baseline for comparison to diseased tissues, and will aid in the identification of tissue-specific functions. In addition, our analysis identifies potential molecular markers for detection of injury to specific organs and tissues, and provides a foundation for selection of potential targets for selective anticancer therapy.

Monitoring of a pharmaceutical nanomilling process using grating light reflection spectroscopy

An optical diagnostic method, grating light reflection spectroscopy (GLRS), has been demonstrated for the in situ monitoring of properties of heterogeneous matrices in industrial processes. The technique is based on measurements near the critical points of intensity and phase in waves reflected from a transmission diffraction grating in contact with a diagnostic sample. The features contained in the reflection spectrum near these thresholds allow for the simultaneous determination of the real and imaginary parts of the dielectric function of the sample. Using these data, the milling progress of highly concentrated fluid suspensions is observed as the material is milled from approximately 40 mm to 160 nm in diameter. A theoretical model that closely resembles experimentally determined spectra was constructed and applied in combination with principal components analysis (PCA) to demonstrate that GLRS can be used to closely monitor changes in the mean particle size of the nanomilled drug product.

Only the CD62L+ subpopulation of CD4+CD25+ regulatory T cells protects from lethal acute GVHD

CD4+CD25+ regulatory T (Treg) cells are potent modulators of alloimmune responses. In murine models of allogeneic bone marrow transplantation, adoptive transfer of donor CD4+CD25+ Treg cells protects recipient mice from lethal acute graft-versus-host disease (aGVHD) induced by donor CD4+CD25- T cells. Here we examined the differential effect of CD62L+ and CD62L- subsets of CD4+CD25+ Treg cells on aGVHD-related mortality. Both subpopulations showed the characteristic features of CD4+CD25+ Treg cells in vitro and did not induce aGVHD in vivo. However, in cotransfer with donor CD4+CD25- T cells, only the CD62L+ subset of CD4+CD25+ Treg cells prevented severe tissue damage to the colon and protected recipients from lethal aGVHD. Early after transplantation, a higher number of donor-type Treg cells accumulated in host mesenteric lymph node (LN) and spleen when CD4+CD25+CD62L+ Treg cells were transferred compared with the CD62L- subset. Subsequently, CD4+CD25+CD62L+ Treg cells showed a significantly higher capacity than their CD62L- counterpart to inhibit the expansion of donor CD4+CD25- T cells. The ability of Treg cells to efficiently enter the priming sites of pathogenic allo-reactive T cells appears to be a prerequisite for their protective function in aGVHD.

Gene expression profiling identifies clinically relevant subtypes of prostate cancer

Prostate cancer, a leading cause of cancer death, displays a broad range of clinical behavior from relatively indolent to aggressive metastatic disease. To explore potential molecular variation underlying this clinical heterogeneity, we profiled gene expression in 62 primary prostate tumors, as well as 41 normal prostate specimens and nine lymph node metastases, using cDNA microarrays containing approximately 26,000 genes. Unsupervised hierarchical clustering readily distinguished tumors from normal samples, and further identified three subclasses of prostate tumors based on distinct patterns of gene expression. High-grade and advanced stage tumors, as well as tumors associated with recurrence, were disproportionately represented among two of the three subtypes, one of which also included most lymph node metastases. To further characterize the clinical relevance of tumor subtypes, we evaluated as surrogate markers two genes differentially expressed among tumor subgroups by using immunohistochemistry on tissue microarrays representing an independent set of 225 prostate tumors. Positive staining for MUC1, a gene highly expressed in the subgroups with "aggressive" clinicopathological features, was associated with an elevated risk of recurrence (P = 0.003), whereas strong staining for AZGP1, a gene highly expressed in the other subgroup, was associated with a decreased risk of recurrence (P = 0.0008). In multivariate analysis, MUC1 and AZGP1 staining were strong predictors of tumor recurrence independent of tumor grade, stage, and preoperative prostate-specific antigen levels. Our results suggest that prostate tumors can be usefully classified according to their gene expression patterns, and these tumor subtypes may provide a basis for improved prognostication and treatment stratification.

Approach to the Determination of Hydrate Form Conversions of Drug Compounds and Solid Dosage Forms by Near‐Infrared Spectroscopy

Near-infrared (IR) spectroscopy is used for the rapid, nondestructive identification and quantitation of the hydrate form of drug compounds forming both single and multiple hydration states. Near-IR is shown to be useful in both bulk drug and in finished solid dosage forms. The capability of near-IR to nondestructively analyze samples allows the kinetics of hydrate form conversions to be measured directly in formulated products. In addition, the environmental conditions for stability of the individual hydration states are mapped out using near-IR spectroscopy. Detailed molecular mechanisms are given to account for the near-IR spectral changes that occur upon hydration. The technique is applied in both laboratory studies as well as in a process environment for at-line analysis of active pharmaceutical ingredient hydration state during pharmaceutical processing.

Chlamydia pneumoniae and coronary artery disease: legitimized linkages?

Chlamydia pneumoniae (Cp) infection in early life may accelerate atherosclerosis over ensuing decades, leading to cardiovascular complications. Cp promotes endothelial dysfunction and may modulate inflammation underlying atherosclerosis. It represents a biologically plausible candidate for the causation of atherosclerosis. Other infections simultaneously occurring with Cp may result in a synergistic effect to promote atherosclerosis. Studies on the treatment of Cp with antibiotics indicates decreased rates of infection, modulation of inflammation and in some settings, fewer cardiovascular complications.

Common lymphoid progenitors rapidly engraft and protect against lethal murine cytomegalovirus infection after hematopoietic stem cell transplantation

Lymphoid deficiency after allogeneic hematopoietic cell transplantation (HCT) results in increased susceptibility to infection; however, transplantation of mature lymphocytes frequently results in a serious complication known as graft-versus-host disease (GVHD). Here we demonstrate in mice that both congenic as well as allogeneic transplantation of low numbers of highly purified common lymphoid progenitors (CLPs)-a rare population of lymphoid-lineage-committed bone marrow cells-accelerates immune reconstitution after lethal irradiation and rescue with hematopoietic stem cells (HSCs). After congenic transplantation, 3 x 10(3) CLPs protected against murine cytomegalovirus (MCMV) infection at a level roughly equivalent to 107 unfractionated lymph node cells. In the allogeneic model of matched unrelated donor HSC transplantation, cotransplantation of 3 x 10(3) CLPs protected thymus-bearing as well as thymectomized hosts from MCMV infection and attenuated disease severity. Immunohistochemistry in combination with antibody depletion of T and natural killer (NK) cells confirmed that CLP-derived as well as residual host lymphocytes contribute to antiviral protection. Importantly, transplantation of allogeneic CLPs provided a durable antiviral immunity without inducing GVHD. These data support the potential for composing grafts with committed progenitors to reduce susceptibility to viral infection following HCT.

Treatment with humanized monoclonal antibodies against CD80 and CD86 combined with sirolimus prolongs renal allograft survival in cynomolgus monkeys

BACKGROUND

Co-stimulatory blockade has been shown to prolong allograft survival in different transplant models. We investigated the effect of combining humanized anti-CD80 and anti-CD86 monoclonal antibodies (mAb) with sirolimus in cynomolgus monkey renal transplant recipients.

METHODS

After renal transplantation, groups of four animals were treated daily with sirolimus, sirolimus and nine weekly doses of mAb, two weekly doses of mAb, or sirolimus and two weekly doses of mAb.

RESULTS

Survival was significantly better in monkeys treated with the combination of sirolimus and mAb when compared with treatment with either agent alone (P=0.0067 by log-rank analysis). When combined with sirolimus, nine weekly doses of mAb did not result in an additional survival benefit compared with only two mAb doses (P=0.74). None of the treatment regimens used in this study resulted in development of transplantation tolerance.

CONCLUSIONS

Sirolimus can be successfully combined with humanized mAb against CD80 and CD86. Induction with a short course of mAb is effective in prolonging allograft survival in combination with sirolimus.

Host conditioning with total lymphoid irradiation and antithymocyte globulin prevents graft-versus-host disease: the role of CD1-reactive natural killer T cells

Our previous studies in mice showed that the nonmyeloablative conditioning regimen of fractionated irradiation of the lymphoid tissues (total lymphoid irradiation; TLI) and depletive anti-T-cell antibodies (anti-thymocyte serum) markedly increased the percentage of regulatory DX5+ and natural killer 1.1+ T cells in the mouse spleen, and prevented acute lethal graft-versus-host disease (GVHD) in BALB/c mice (H-2(d)) following the transplantation of bone marrow (BM) and peripheral blood mononuclear cells (PBMC) from C57BL/6 (H-2(b)) donors. The object of the current study was to determine whether the TLI and anti-thymocyte serum regimen protected natural killer T-cell deficient CD1(-/-) BALB/c mice against GVHD after BM and PBMC transplantation from C57BL/6 donors, and whether a similar conditioning regimen of TLI and anti-thymocyte globulin (ATG) can prevent GVHD in Lewis rat (RT1(l)) hosts after BM and PBMC transplantation from ACI rat (RT1(a)) donors. The experimental results in mice showed that, although wild-type BALB/c hosts are protected in association with a marked increase in CD1- reactive T cells expressing the invariant TCR identified with a CD1 tetramer reagent; CD1(-/-) BALB/c hosts are not. Studies of chimeric donor cells in mice protected from GVHD showed donor T-cell polarization to a Th2 cytokine pattern. Results in rats showed that approximately 1000 fold more donor PBMC cells were required to induce a similar incidence of lethal GVHD in TLI and ATG conditioned hosts as compared with hosts conditioned with single-dose total-body irradiation or total-body irradiation and ATG. Surviving TLI and ATG conditioned rat hosts were complete chimeras. In conclusion, the TLI and ATG/anti-thymocyte serum conditioning regimen protects against GVHD in rats and mice, and regulatory natural killer T cells are required for protection.

Elevation of cardiac troponin I indicates more than myocardial ischemia

Elevated cardiac troponin I (cTnI) levels in patients hospitalized with chest pain often lead to a diagnosis of acute myocardial infarction (MI) or unstable angina. However, as we describe in this review, this finding may occur in other conditions, leading to an incorrect diagnosis and other, sometimes invasive, tests. We review briefly cTnI, its release and detection. We describe the various conditions that may cause an elevated cTnI level and give possible explanations for these findings, and we offer some guidelines for diagnosis in patients with an elevated cTnI.

Can angiotensin-converting enzyme inhibitors reverse atherosclerosis?

Angiotensin II, a potent vasoconstrictor, is mainly present in the vascular endothelium. Multiple studies have confirmed that angiotensin-converting enzyme (ACE) inhibitors, which block the formation of angiotensin II, lower blood pressure and also improve heart failure. These agents not only have beneficial hemodynamic effects but also bestow additional benefits on vascular function and prevent clinical cardiovascular events in patients at risk for coronary artery disease. These latter benefits may represent effects of ACE inhibitors on local endocrine pathways, inflammatory processes, and atherosclerosis taking place within the arterial wall. Current evidence suggests that, although ACE inhibitors may not substantially reverse atherosclerotic plaque already present, they may slow the progression of such atherosclerotic lesions. In addition, by modulating inflammatory pathways within and adjacent to the atherosclerotic lesion, they may stabilize an unstable plaque and therefore decrease the risk of plaque rupture and its complications.

Spectroscopic approach for on-line monitoring of particle size during the processing of pharmaceutical nanoparticles

A novel application of near-infrared (near-IR) spectroscopy for the on-line determination of nanoparticle size of a drug compound in a high solids dispersion is described. The on-line spectroscopic technique provides real-time data for process monitoring and control and overcomes the limitations that are encountered using laboratory-based instrumentation for nanoparticle size determination. Near-IR spectroscopy is capable of providing an accuracy of 2.4 nm near the endpoint of particle production, where the volume-weighted D90 particle size is determined to be 200-220 nm. The accuracy is adequate for endpoint control, which minimizes excess processing and provides control over the particle size throughout nanoparticle production.

Distribution of monoclonal antiferritin antibody in Kaposi's sarcoma, Hodgkin's disease, and hepatocellular carcinoma

The immunotherapeutic treatment of cancers using antibodies (naked or conjugated to a drug, toxin, or radionuclide) relies upon the preferential expression of a targeted antigen on the cancer cell compared to normal tissues. Polyclonal antiferritin antisera have shown selective distribution and therapeutic efficacy when radiolabeled in Hodgkin's disease and hepatoma. In this immunohistochemical study, we investigated the distribution of ferritin in tumors from 6 patients with Kaposi's sarcoma, 12 patients with Hodkgin's disease, and 9 patients with hepatoma, as well as in selected normal tissues. We found that the monoclonal antiferritin antibody binds primarily to histiocytes in samples from Kaposi's sarcoma and Hodgkin's disease. One hepatocellular carcinoma showed diffuse cytoplasmic staining with ferritin. Deposition of the monoclonal antibody was not detectable in the remaining hepatocellular carcinoma samples.

Chlamydia pneumoniae and coronary artery disease: the antibiotic trials

Parallel with the mounting evidence that atherosclerosis has a major inflammatory component, provoking agents that may initiate and drive this process have been sought. Infectious agents such as Chlamydia pneumoniae have been alleged to be activators of inflammation that may contribute to atherosclerosis and thus coronary artery disease (CAD) and its associated complications. A logical pneumoniae extension of this theory whether treating C pneumoniae infection with antibiotics and/or modulating inflammatory processes can affect CAD and its sequelae. This article discusses the potential role of C pneumoniae in atherosclerosis, its detection, and the rationale for antibiotics. Additionally, it summarizes the current randomized clinical trials of antichlamydial antibiotics in patients with CAD and draws conclusions based on the results.

Peripheral arterial disease--Part II: Management

While knowledge about peripheral arterial disease (PAD) appears well disseminated, the condition still goes largely undiagnosed and untreated. In PART 1 of this paper, we summarized the diagnosis, epidemiology and risk factors for PAD. Non-invasive treatment involves management of risk factors and targeted drug therapy. Invasive strategies include angioplasty, angiogenesis and surgery. Dealing with both the structural factors (physical plaque morphology) and functional ones (endothelial function) are important in effectively managing PAD. This paper (PART 2) deals with the management (medical and surgical) of PAD.

Fluoride toothpastes for preventing dental caries in children and adolescents

BACKGROUND

Fluoride toothpastes have been widely used for over three decades and remain a benchmark intervention for the prevention of dental caries.

OBJECTIVES

To determine the effectiveness and safety of fluoride toothpastes in the prevention of caries in children and to examine factors potentially modifying their effect.

SEARCH STRATEGY

We searched the Cochrane Oral Health Group's Trials Register (May 2000), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2000), MEDLINE (1966 to January 2000), plus several other databases. We handsearched journals, reference lists of articles and contacted selected authors and manufacturers.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials with blind outcome assessment, comparing fluoride toothpaste with placebo in children up to 16 years during at least one year. The main outcome was caries increment measured by the change in decayed, missing and filled tooth surfaces (D(M)FS).

DATA COLLECTION AND ANALYSIS

Inclusion decisions, quality assessment and data extraction were duplicated in a random sample of one third of studies, and consensus achieved by discussion or a third party. Authors were contacted for missing data. The primary measure of effect was the prevented fraction (PF) that is the difference in caries increments between the treatment and control groups expressed as a percentage of the increment in the control group. Random effects meta-analyses were performed where data could be pooled. Potential sources of heterogeneity were examined in random effects meta-regression analyses.

MAIN RESULTS

Seventy-four studies were included. For the 70 that contributed data for meta-analysis (involving 42,300 children) the D(M)FS pooled PF was 24% (95% confidence interval (CI), 21 to 28%; p<0.0001). This means that 1.6 children need to brush with a fluoride toothpaste (rather than a non-fluoride toothpaste) over three years to prevent one D(M)FS in populations with caries increment of 2.6 D(M)FS per year. In populations with caries increment of 1.1 D(M)FS per year, 3.7 children will need to use a fluoride toothpaste for three years to avoid one D(M)FS. There was clear heterogeneity, confirmed statistically (p<0.0001). The effect of fluoride toothpaste increased with higher baseline levels of D(M)FS, higher fluoride concentration, higher frequency of use, and supervised brushing, but was not influenced by exposure to water fluoridation. There is little information concerning the deciduous dentition or adverse effects (fluorosis).

REVIEWER'S CONCLUSIONS

Supported by more than half a century of research, the benefits of fluoride toothpastes are firmly established. Taken together, the trials are of relatively high quality, and provide clear evidence that fluoride toothpastes are efficacious in preventing caries.

Peripheral arterial disease--Part I: Diagnosis, epidemiology and risk factors

While knowledge about peripheral arterial disease (PAD) appears well disseminated, the condition still goes largely undiagnosed and untreated. We reviewed the current literature and found that PAD is a common condition that is equally prevalent in men and women. Most cases are asymptomatic and more so in women. Having PAD increases morbidity and mortality, as well as concomitant cardiovascular disease. Given the lack of symptoms in most patients, we recommend diagnosing PAD using non-invasive instruments such as the Ankle-Brachial Index (ABI). This paper deals with the diagnosis, epidemiology and risk factors for PAD.

Nonlinear systems in medicine

Many achievements in medicine have come from applying linear theory to problems. Most current methods of data analysis use linear models, which are based on proportionality between two variables and/or relationships described by linear differential equations. However, nonlinear behavior commonly occurs within human systems due to their complex dynamic nature; this cannot be described adequately by linear models. Nonlinear thinking has grown among physiologists and physicians over the past century, and non-linear system theories are beginning to be applied to assist in interpreting, explaining, and predicting biological phenomena. Chaos theory describes elements manifesting behavior that is extremely sensitive to initial conditions, does not repeat itself and yet is deterministic. Complexity theory goes one step beyond chaos and is attempting to explain complex behavior that emerges within dynamic nonlinear systems. Nonlinear modeling still has not been able to explain all of the complexity present in human systems, and further models still need to be refined and developed. However, nonlinear modeling is helping to explain some system behaviors that linear systems cannot and thus will augment our understanding of the nature of complex dynamic systems within the human body in health and in disease states.

Fluoride gels for preventing dental caries in children and adolescents

BACKGROUND

Topically applied fluoride gels have been widely used as a caries-preventive intervention in dental surgeries and school-based programs for over two decades.

OBJECTIVES

To determine the effectiveness and safety of fluoride gels in the prevention of dental caries in children and to examine factors potentially modifying their effect.

SEARCH STRATEGY

Multiple electronic database searches, reference lists of articles, journal handsearch, selected authors and manufacturers.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials with blind outcome assessment, comparing fluoride gel with placebo or no treatment in children up to 16 years during at least one year. The main outcome was caries increment measured by the change in decayed, missing and filled tooth surfaces (D(M)FS).

DATA COLLECTION AND ANALYSIS

Inclusion decisions, quality assessment and data extraction were duplicated in a random sample of one third of studies, and consensus achieved by discussion or a third party. Study authors were contacted for missing data. The primary outcome measure was the prevented fraction (PF), that is the caries increment in the treatment group expressed as a percentage of the control group. Random effects meta-analyses were performed where data could be pooled. Potential sources of heterogeneity were examined in random effects meta-regression analyses.

MAIN RESULTS

Twenty-five studies were included, involving 7747 children. For the 23 that contributed data for meta-analysis, the D(M)FS pooled prevented fraction estimate was 28% (95% CI, 19% to 37%; p<0.0001). There was clear heterogeneity, confirmed statistically (p<0.0001). The effect of fluoride gel varied according to type of control group used, with D(M)FS PF on average being 19% (95% CI, 5% to 33%; p<0.009) higher in non-placebo controlled trials. A funnel plot of the 23 studies indicated a relationship between prevented fraction and study precision. Only two trials reported on adverse events.

REVIEWER'S CONCLUSIONS

There is clear evidence of a caries-inhibiting effect of fluoride gel. The best estimate of the magnitude of this effect, based on the 14 placebo-controlled trials, is a 21% reduction (95% CI, 14 to 28%) in D(M)FS. This corresponds to an NNT of 2 (95% CI, 1 to 3) to avoid 1 D(M)FS in a population with a caries increment of 2.2 D(M)FS/year, or an NNT of 24 (95% CI, 18 to 36) based on an increment of 0.2 D(M)FS/year. There is little information concerning deciduous dentition, on adverse effects or on acceptability of treatment. Future trials should include assessment of potential adverse effects.

Fluoride varnishes for preventing dental caries in children and adolescents

BACKGROUND

Topically applied fluoride varnishes have been used extensively as an operator-applied caries-preventive intervention for over two decades.

OBJECTIVES

To determine the effectiveness and safety of fluoride varnishes in the prevention of dental caries in children and to examine factors potentially modifying their effect.

SEARCH STRATEGY

Multiple electronic database searches, reference lists of articles, journal handsearch, selected authors and manufacturers.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials with blind outcome assessment, comparing fluoride varnish with placebo or no treatment in children up to 16 years during at least one year. The main outcome was caries increment measured by the change in decayed, missing and filled tooth surfaces (D(M)FS).

DATA COLLECTION AND ANALYSIS

Inclusion decisions, quality assessment and data extraction were duplicated in a random sample of one third of studies, and consensus achieved by discussion or a third party. Study authors were contacted for missing data. The primary measure of effect was the prevented fraction (PF), that is the difference in caries increments between the treatment and control groups expressed as a percentage of the increment in the control group. Random effects meta-analyses were performed where data could be pooled. Potential sources of heterogeneity were examined in random effects meta-regression analyses.

MAIN RESULTS

Nine studies were included, involving 2709 children. For the seven that contributed data for the main meta-analysis, the D(M)FS pooled prevented fraction estimate was 46% (95% CI, 30% to 63%; p<0.0001). There was substantial heterogeneity, confirmed statistically (p<0.0001). The pooled d(e/m)fs prevented fraction estimate was 33% (95% CI, 19% to 48%; p<0.0001). No significant association between estimates of D(M)FS prevented fractions and baseline caries severity or background exposure to fluorides was found in meta-regression, and a funnel plot of the seven studies indicated no relationship between prevented fraction and study precision. In both methods, power is limited when only a few trials are included.

REVIEWER'S CONCLUSIONS

The review suggests a substantial caries-inhibiting effect of fluoride varnish in both the permanent and the deciduous dentitions based largely on trials with no treatment controls. There is little information concerning acceptability of treatment or possible side effects in the included trials. Given the relatively poor quality of most of the included studies and the wide confidence intervals around the estimates of effect, there remains a need for further trials. It is important that these trials should be of high quality and include assessment of potential adverse effects.