BACKGROUND

It has been suggested that nutrition and food patterns, particularly high consumption of animal fat and low intake of fish products, may play a role in the aetiology of multiple sclerosis (MS).

METHODS

The relation between nutritional factors and MS was studied among 197 incident cases and 202 frequency matched controls in metropolitan Montreal during 1992-1995. Dietary information was collected by employing a 164-item food frequency questionnaire in a face-to-face interview.

RESULTS

An inverse association was observed between high body mass index (BMI) and the risk of MS, with an odds ratio (OR) of 0.76 (95% confidence interval [CI]: 0.61-0.95), per 5-unit increase in BMI, both sexes combined. In addition, taller women showed a greater risk for MS; the OR per 10 cm increase in height was 1.58 (95% CI: 1.06-2.35). In continuous variable analyses, using the difference between the lowest and highest quartile of intake as a unit, a positive association was observed with energy and animal fat intake. The OR per 897 kcal increase was 2.03 (95% CI: 1.13-3.67) and 1.99 (95% CI: 1.12-3.54) per 33 g of animal fat intake above the baseline. A significant protective effect was observed with other nutrients, including vegetable protein, dietary fibre, cereal fibre, vitamin C, thiamin, riboflavin, calcium, and potassium. Similar trends were seen for males and females when analysed separately. With respect to specific foods (as opposed to nutrients), a higher intake of fruit juices was inversely associated with risk (OR = 0.82; 95% CI: 0.74-0.92). A protective effect was also observed with cereal/breads intake for all cases combined (OR = 0.62; 95% CI: 0.40-0.97) and for fish among women only; pork/hot dogs (OR = 1.24; 95% CI: 1.02-1.51) and sweets/candy (OR = 1.29; 95% CI: 1.07-1.55) were positively associated with risk.

CONCLUSIONS

The study generally supports a protective role for components commonly found in plants (fruit/vegetables and grains) and an increased risk with high energy and animal food intake.

BACKGROUND

The genome is constantly assaulted by oxidation reactions which are likely to be associated with oxygen metabolism, and oxidative lesions are generated by many types of oxidants. Such genotoxin-induced alterations in the genomic message have been implicated in aging and in several pathophysiological processes, particularly those associated with cancer. The guanine base (G) in genomic DNA is highly susceptible to oxidative stress due to having the lowest oxidation potential. Therefore, G-C->>T-A and G-C->>C-G transversion mutations frequently occur under oxidative conditions. One typical lesion of G is 8-oxo-7,8-dihydro-guanine (8-oxoG), which can pair with A. This pairing may cause G-C->>T-A transversion mutations. Although the number of G-C->>C-G transversions is rather high under specific oxidation conditions such as riboflavin photosensitization, the molecular basis of G-C->>C-G transversions is not known.

RESULTS

To determine which oxidative products are responsible for G-C->>C-G transversion mutations, we photooxidized 5'-d(AAAAAAGGAAAAAA)/5'-d(TTTTTTCCTTTTTT) using either riboflavin or anthraquinone (AQ) carboxylate under UV irradiation. Prolonged low-temperature (4 degrees C) enzymatic digestion of photoirradiated sample indicated that under both conditions the amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) initially increased with decreasing amounts of 2'-deoxyguanosine (dG), then decreased with the formation of 2-amino-5-[(2-deoxy-beta-D-erythro-pentofuranosyl)amino]-4H-imidazol-4-one (dIz), suggesting that nascent 8-oxoG was further oxidized to 2,5-diamino-4H-imidazol-4-one (Iz) in duplex DNA. Photoirradiation of an AQ-linked oligomer with a complementary strand containing 8-oxoG indicated that 8-oxoG residues were oxidized to Iz. These results indicate that Iz is formed from 8-oxoG through long-range hole migration. Primer extension experiments using a template containing Iz demonstrated that only dGTP is specifically incorporated opposite Iz suggesting that specific Iz-G base pairs are formed. The 'reverse' approach consisting of DNA polymerization using dIzTP showed that dIzTP is incorporated opposite G, further confirming the formation of a Iz-G base pair.

CONCLUSIONS

HPLC product analysis demonstrated that Iz is a key oxidation product of G through 8-oxoG in DNA photosensitized with riboflavin or anthraquinone. Photoreaction of AQ-linked oligomer confirmed that Iz is formed from 8-oxoG through long-range hole migration. Two sets of primer extension experiments demonstrated that Iz can specifically pair with G in vitro. Specific Iz-G base pair formation can explain the G-C->>C-G transversion mutations that appear under oxidative conditions.

Staphylococcus aureus is a preeminent bacterial pathogen capable of colonizing diverse ecological niches within its human host. We describe here the pangenome of S. aureus based on analysis of genome sequences from 64 strains of S. aureus spanning a range of ecological niches, host types, and antibiotic resistance profiles. Based on this set, S. aureus is expected to have an open pangenome composed of 7,411 genes and a core genome composed of 1,441 genes. Metabolism was highly conserved in this core genome; however, differences were identified in amino acid and nucleotide biosynthesis pathways between the strains. Genome-scale models (GEMs) of metabolism were constructed for the 64 strains of S. aureus These GEMs enabled a systems approach to characterizing the core metabolic and panmetabolic capabilities of the S. aureus species. All models were predicted to be auxotrophic for the vitamins niacin (vitamin B3) and thiamin (vitamin B1), whereas strain-specific auxotrophies were predicted for riboflavin (vitamin B2), guanosine, leucine, methionine, and cysteine, among others. GEMs were used to systematically analyze growth capabilities in more than 300 different growth-supporting environments. The results identified metabolic capabilities linked to pathogenic traits and virulence acquisitions. Such traits can be used to differentiate strains responsible for mild vs. severe infections and preference for hosts (e.g., animals vs. humans). Genome-scale analysis of multiple strains of a species can thus be used to identify metabolic determinants of virulence and increase our understanding of why certain strains of this deadly pathogen have spread rapidly throughout the world.

The purpose of this study is to examine the relationship between the free radical scavenging activities and the chemical structures of tea catechins ((-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC) and (-)-epicatechin (EC)) and their corresponding epimers ((-)-gallocatechin gallate (GCG), (-)-gallocatechin (GC) and (+)-catechin ((+)-C)). With electron spin resonance (ESR) we investigated their scavenging effects on superoxide anions (O-.2) generated in the irradiated riboflavin system, singlet oxygen(1O2) generated in the photoradiation-hemoporphyrin system, the free radicals generated from 2,2'-azobis(2-amidinopropane)hydrochloride (AAPH) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. The results showed that the scavenging effects of galloylated catechins (EGCG and GCG) on the four free radicals were stronger than those of nongalloylated catechins (EGC, GC, EC, (+)-C), and the scavenging effects of EGC and GC were stronger than those of EC and (+)-C. Thus, it is suggested that the presence of the gallate group at the 3 position plays the most important role in their free radical-scavenging abilities and an additional insertion of the hydroxyl group at the 5' position in the B ring also contributes to their scavenging activities. Moreover, the corresponding phenoxyl radicals formed after the reaction with O-.2 were trapped by DMPO and the ESR spectra of DMPO/phenoxyl radical adducts were observed (aN=15.6 G and aHbeta=21.5 G). No significant differences were found between the scavenging effects of the catechins and their epimers when their concentrations were high. However, significant differences were observed at relatively low concentrations, and the lower their concentrations, the higher the differences. The scavenging abilities of GCG, GC and (+)-C were stronger than those of their corresponding epimers (EGCG, EGC and EC). The differences between their sterical structures played a more important role in their abilities to scavenge large free radicals, such as the free radicals generated from AAPH and the DPPH radical, than to scavenge small free radicals, such as O-.2 and 1O2, especially in the case with EGCG and GCG with more bulky steric hindrance.

OBJECTIVE

To study the progression rate of keratoconus and assess the clinical outcome of corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A light in children and adolescent patients up to 3 years after treatment.

METHODS

Fifty-nine eyes from 42 children and adolescents (aged 9 to 19 years) with confirmed keratoconus were included in this retrospective interventional cohort study. Refraction, slit-lamp examination, Placido-based corneal topography, and Scheimpflug imaging were performed bilaterally in all patients preoperatively and at 6 and 12 months postoperatively. Maximal keratometry readings (Kmax), corrected distance visual acuity (CDVA), corneal thickness, and the keratoconus index (KI) were analyzed. Follow-up was up to 36 months (mean follow-up: 26.3 months [range: 12 to 36 months]).

RESULTS

Fifty-two of the 59 eyes enrolled in this study showed progression, corresponding to a progression rate of 88%. Forty-six eyes were treated by CXL. Maximal keratometry, CDVA, and KI showed significant changes over the follow-up period. However, significant Kmax reduction observed up to 24 months after CXL lost significance at 36 months.

CONCLUSIONS

Cross-linking seems to be safe in children and adolescents. Progression of keratoconus occurred in 88%. We propose that awaiting documentation of progression is not mandatory and CXL in children and adolescents should be performed as soon as the diagnosis has been made. However, the effect of arrest of disease progression might not be as long-lasting as in adults and longer follow-up is needed to verify this trend.

OBJECTIVE

: To report a case of polymicrobial keratitis caused by Streptococcus salivarius, Streptococcus oralis, and coagulase-negative Staphylococcus sp. in a patient who underwent collagen cross-linking for keratoconus.

METHODS

: Case report.

RESULTS

: A 32-year-old male presented with a 1-day history of a painful red eye, occurring 3 days after he had undergone a collagen cross-linking with riboflavin and UV-A on his left eye for keratoconus. He admitted to removing his bandage contact lens and cleaning it in his mouth before reapplying it in his eye. On presentation, a severe keratitis with an 8-mm epithelial defect and 360-degree ring infiltrate was found. Culture results from his contact lens were positive for S. salivarius and S. oralis, and coagulase-negative Staphylococcus sp. were grown from his corneal scrapings.

CONCLUSIONS

: Collagen cross-linking is a promising procedure for the treatment of progressive keratoconus with minimal reported side effects. However, the possibility of a secondary infection after the procedure exists because the patient is subjected to epithelial debridement and the application of a soft contact lens. The role of the UV light on the immune mechanisms of the cornea and its effect on corneal wound healing warrant further investigation.

OBJECTIVE

Collagen cross-linking using combined riboflavin/UVA treatment has been shown to increase the biomechanical rigidity of the cornea and has been used successfully for the treatment of progressive keratoconus. From morphological and biochemical investigations, a different degree of cross-linking for the anterior and posterior stroma by the treatment is suggested. The present study was undertaken to better evaluate this effect by testing the thermomechanical behavior.

METHODS

Ten 10 x 5 mm corneal strips from porcine cadaver eyes enucleated within 5 h post mortem were cross-linked using the photosensitizer riboflavin and UVA irradiation (370 nm, irradiance = 3 mW/cm(2)) for 30 min and compared to ten untreated corneal strips and ten corneal strips cross-linked with 0.1% glutaraldehyde. The temperature in a water bath was raised from 60 to 95 degrees C with temperature increments of 1 degrees C per minute. The hydrothermal shrinkage of the corneal strips was measured in 2.5 degrees C steps using a micrometer. In addition, six 10-mm whole corneal buttons were cross-linked with riboflavin/UVA and immersed into water at 70 or 75 degrees C.

RESULTS

The maximal hydrothermal shrinkage for the untreated control specimens and the posterior portion of the riboflavin/UVA-treated corneas was at 70 degrees C, for the anterior portion of the cornea cross-linked by riboflavin/UVA at 75 degrees C and for glutaraldehyde-cross-linked cornea at 90 degrees C. In the cross-linked corneal buttons, a typical mushroom-like shape was observed at 70 degrees C and a cylinder shape at 75 degrees C.

CONCLUSIONS

The different degree of collagen cross-linking in the corneal stroma after riboflavin/UVA treatment is reflected by the differences in the maximal shrinkage temperature of the anterior and posterior portion. Therefore, in the corneas cross-linked with riboflavin/UVA a higher shrinkage temperature was observed for the anterior portion of the cornea (75 degrees C) compared to the posterior stroma (70 degrees C) due to the higher degree of cross-linking of the anterior stroma. The anterior localization of the cross-linking effect is advantageous for the endothelium and for the preservation of the anterior corneal curvature.

Listeria monocytogenes was examined for superoxide dismutase(SOD) activity. Two catalase-negative strains possessed at least twofold greater SOD activities than the catalase-positive L. monocytogenes strains examined. Growth conditions such as aeration and iron concentration influenced the specific activity of SOD obtained from cells cultured in defined media. L. monocytogenes SOD from crude extracts and after partial purification was analyzed by polyacrylamide gel electrophoresis. Iron was associated with the single band of SOD activity detected in the gels. SOD activity appeared to be primarily extracytoplasmic. Survival of organisms in a superoxide-generating medium was studied, with photoactivation of riboflavin used as the source of free radical formation. Virulent, catalase-positive L. monocytogenes strains were relatively resistant to killing in a pH 7 superoxide-containing medium. An intact-cell assay for SOD was developed, which used the superoxide-generating system and employed the superoxide-dependent oxidation of sulfite, added to the medium, and inhibition of this oxidation by SOD. Maximal SOD activites of intact cells were observed when 100 to 400 micrograms (dry weight) of viable Listeria cells per ml was added to the medium. A possible role for SOD in the pathogenesis of listeric infection is discussed.

This work shows that the ribC wild-type gene product has both flavokinase and flavin adenine dinucleotide synthetase (FAD-synthetase) activities. RibC plays an essential role in the flavin metabolism of Bacillus subtilis, as growth of a ribC deletion mutant strain was dependent on exogenous supply of FMN and the presence of a heterologous FAD-synthetase gene in its chromosome. Upon cultivation with growth-limiting amounts of FMN, this ribC deletion mutant strain overproduced riboflavin, while with elevated amounts of FMN in the culture medium, no riboflavin overproduction was observed. In a B. subtilis ribC820 mutant strain, the corresponding ribC820 gene product has reduced flavokinase/FAD-synthetase activity. In this strain, riboflavin overproduction was also repressed by exogenous FMN but not by riboflavin. Thus, flavin nucleotides, but not riboflavin, have an effector function for regulation of riboflavin biosynthesis in B. subtilis, and RibC seemingly is not directly involved in the riboflavin regulatory system. The mutation ribC820 leads to deregulation of riboflavin biosynthesis in B. subtilis, most likely by preventing the accumulation of the effector molecule FMN or FAD.

BACKGROUND

For decades, the coronary heart disease (CHD) mortality rate has been four or more times higher in Finland than in France despite comparable intakes of dietary cholesterol and saturated fat. A potential answer to this paradox is provided by this study of 40 countries and the analyses of other nutrients in the diets besides cholesterol and saturated fat.

RESULTS

CHD death rates for men aged 55 to 64 years were derived from the World Health Organization annual vital statistics. Dietary intakes were gathered from the Food and Agriculture Organization of the United Nations database. Forty countries at various levels of economic development and 40 dietary variables were investigated, including a lipid score that combined the intakes of cholesterol and saturated fat (Cholesterol-Saturated Fat Index [CSI]). The CSI was significantly and positively related to CHD mortality in the 40 countries. The countries with low CSIs had low CHD death rates. Countries with high CSIs had a wide range of CHD death rates. France, Finland, and other Western industrialized countries had similar CSIs. After adjusting for cholesterol and saturated fat, milk and many components of milk (butterfat, milk protein, calcium from milk, and riboflavin) and total calcium remained positively related to CHD mortality for all 40 countries. There were differences in the consumption of these foods and nutrients in France and Finland. Milk and butterfat (fat from milk, cream, cheese, and butter) consumption was higher in Finland than in France. The consumption of plant foods, recently shown to be protective against CHD (vegetables and vegetable oils containing monounsaturated and polyunsaturated fatty acids), was greater in France than in Finland.

CONCLUSIONS

Over the years, France and Finland, with similar intakes of cholesterol and saturated fat, consistently have had very different CHD mortality rates. This paradox may be explained as follows. Given a high intake of cholesterol and saturated fat, the country in which people also consume more plant foods, including small amounts of liquid vegetable oils, and more vegetables (more antioxidants) had lower rates of CHD mortality. On the other hand, milk and butterfat were associated with increased CHD mortality, possibly through their effects on thrombosis as well as on atherosclerosis.

The risk of developing tuberculosis (TB) may be related to nutritional status. To determine the impact of nutritional status on TB incidence, the authors analyzed data from the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study (NHEFS). NHANES I collected information on a probability sample of the US population in 1971-1975. Adults were followed up in 1982-1992. Incident TB cases were ascertained through interviews, medical records, and death certificates. TB incidences were compared across different levels of nutritional status after controlling for potential confounding using proportional hazards regression appropriate to the complex sample design. TB incidence among adults with normal body mass index was 24.7 per 100,000 person-years (95% confidence interval (CI): 13.0, 36.3). In contrast, among persons who were underweight, overweight, and obese, estimated TB incidence rates were 260.2 (95% CI: 98.6, 421.8), 8.9 (95% CI: 2.2, 15.6), and 5.1 (95% CI: 0.0, 10.5) per 100,000 person-years, respectively. Adjusted hazard ratios were 12.43 (95% CI: 5.75, 26.95), 0.28 (95% CI: 0.13, 0.63), and 0.20 (95% CI: 0.07, 0.62), respectively, after controlling for demographic, socioeconomic, and medical characteristics. A low serum albumin level also increased the risk of TB, but low vitamin A, thiamine, riboflavin, and iron status did not. A population's nutritional profile is an important determinant of its TB incidence.

A characteristic of mucosal-associated invariant T (MAIT) cells is the expression of TRAV1-2(+) T cell receptors (TCRs) that are activated by riboflavin metabolite-based antigens (Ag) presented by the MHC-I related molecule, MR1. Whether the MR1-restricted T cell repertoire and associated Ag responsiveness extends beyond these cells remains unclear. Here, we describe MR1 autoreactivity and folate-derivative reactivity in a discrete subset of TRAV1-2(+) MAIT cells. This recognition was attributable to CDR3β loop-mediated effects within a consensus TRAV1-2(+) TCR-MR1-Ag footprint. Furthermore, we have demonstrated differential folate- and riboflavin-derivative reactivity by a diverse population of "atypical" TRAV1-2(-) MR1-restricted T cells. We have shown that TRAV1-2(-) T cells are phenotypically heterogeneous and largely distinct from TRAV1-2(+) MAIT cells. A TRAV1-2(-) TCR docks more centrally on MR1, thereby adopting a markedly different molecular footprint to the TRAV1-2(+) TCR. Accordingly, diversity within the MR1-restricted T cell repertoire leads to differing MR1-restricted Ag specificity.

In keratoconus, corneal stiffness is decreased. The purposes of this study were to search for techniques to stiffen the cornea and to determine a dose-response relation. The stiffness of collagenous tissues can be increased by cross-linking. Cross-linking techniques--riboflavin and ultraviolet irradiation (365 nm, 2 mW/cm2, 45 min), glutaraldehyde of low concentration, and several aldehyde sugars--were tested on corneas of enucleated porcine eyes. The stress-strain relation was measured and compared to untreated corneas. Aldehyde sugars produced cross-links by nonenzymatic glycation only after a prolonged time (realized in diabetics). Riboflavin and UV seems to be a promising technique to stabilize the cornea by artificial cross-linking.

OBJECTIVE

To compare geometrical shape factors of keratoconus corneas after cross-linking (CXL) by means of Scheimpflug imaging with those of untreated fellow eyes.

METHODS

Institut für Refraktive und Ophthalmo-Chirurgie, Zürich, Switzerland.

METHODS

Scheimpflug imaging of the anterior segments was performed with the Pentacam (Oculus, Wetzlar, Germany) in 21 patients with progressive keratectasia before and after CXL. Only 1 eye per patient was treated with corneal cross-linking using the riboflavin/UV-A approach, the fellow eye serving as control. The following corneal parameters and their postoperative evolution during 1 year after treatment have been evaluated: minimal curvature radius and its location, thickness at the thinnest point, location of the thinnest point, anterior and posterior elevation, conoid asphericity constants of the anterior and posterior surface, and 7 keratoconus indices. Statistical comparison was performed by means of the Wilcoxon test.

RESULTS

None of the treated eyes showed topographic progression in contrast to the untreated group where 8 eyes experienced significant progression. Minimal curvature radius increased significantly after 1 year compared with preoperative (6.14-6.21 mm), whereas in the untreated fellow eye, it significantly decreased (6.94-6.86 mm). Minimal corneal thickness was significantly reduced after treatment (P < 0.002 at 12 months). The cornea showed an evolution toward a more regular shape as indicated by a significant reduction in 4 of 7 keratoconus indices. No complications of CXL occurred in this small study group.

CONCLUSIONS

After cross-linking, the corneal shape undergoes a process of regularization. This process is active during the first year after treatment and may continue. Longer follow-up is warranted to estimate the full amount of regression of the keratectasia after CXL.

The cation pump activity of the ocular lens was damaged by exposure to light in the presence of riboflavin phosphate. The intensity of light was similar to that used for reading purposes. The observed light-induced damage was due to superoxide or its derivatives, the superoxide being produced photochemically. Such damage was attenuated by vitamin C in amounts comparable to that in the aqueous humor. Thus, a new role for the high ascorbate level present in the anterior chamber fluid and the lens has been suggested. Ascorbate in other tissues also might have this novel physiological function of protecting against damage due to superoxide and its derivatives produced during normal cellular oxidation.

Folate plays an important role in carcinogenesis. The enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR), encoded by the MTHFR gene, is involved in this process. We investigated both the independent and joint effects of dietary folate and other methyl-related nutrients, as well as three polymorphisms of MTHFR (677C>T, 1298A>C, and 1793G>A), on endometrial cancer risk in a population-based case-control study. Between 1997 and 2003, 1,204 newly diagnosed endometrial cancer cases and 1,212 controls were recruited among women between the ages of 30 and 69 years in urban Shanghai, China. Information on dietary intake of folate and other methyl-related nutrients, including vitamin B2 (riboflavin), vitamin B6, vitamin B12, and methionine, was derived from a validated food frequency questionnaire. Genotyping was completed on 1,041 cases and 1,030 controls for MTHFR 677C>T (rs1801133), 1298A>C (rs1801131), and 1793 G>A (rs2274967) [corrected] Haplotype estimation of the three single-nucleotide polymorphisms was performed using PHASE software. Odds ratios (OR) and 95% confidence intervals (95% CI) were calculated to evaluate associations of nutrients, MTHFR genotypes, and haplotypes with endometrial cancer risk. A significant inverse association between dietary folate intake and endometrial cancer risk was observed among all subjects and non-B vitamin supplement users. The greatest reduction in endometrial cancer risk was observed among non-users of supplements in the highest quartile of dietary folate intake (OR, 0.5; 95% CI, 0.4-0.7) as compared with those in the lowest quartile. Dietary intake of folate cofactors (methionine, vitamin B2, vitamin B6, and vitamin B12) was not related to risk of endometrial cancer. No association was observed between endometrial cancer and the MTHFR 677C>T, 1298 A>C, and 1793G>A polymorphisms or derived haplotypes. Among non-users of supplements, however, the 1298C and 1793A alleles were associated with a lower risk of endometrial cancer among women with high dietary folate intake but related to a higher risk among those with low dietary folate intake (P(interaction) = 0.08 and 0.03, respectively). Further analysis showed that the lowest risk (OR, 0.6; 95% CI, 0.4-1.1) was among women with the 1298C allele and the highest intake of both folate and riboflavin (P(interaction) = 0.04). A similar association was observed for the 1793A allele (P(interaction) = 0.03). Our findings suggest that folate intake may decrease the risk of endometrial cancer and modify the effect of MTHFR polymorphisms on risk.

BACKGROUND

The aim of this work as to investigate the photochemical interaction used in corneal crosslinking (CXL) as the primary therapy for bacterial keratitis.

METHODS

A prospective non-randomized study was conducted including 16 patients with a clinical diagnosis of bacterial keratitis. No patient had any prior antibiotic treatment for the current infection. Photography and microbial culturing of the infected cornea were performed. Riboflavin was topically administered for 20 min and ultraviolet light (UVA) exposure settings for treatment of keratoconus were used. After the procedure, clinical examinations were done at least once daily until signs of improvement had been established. The frequency of examinations was thereafter reduced. Antibiotic therapy was initiated if infectious progression was suspected. The trial was registered at ISCRTN.org (no: 21432643).

RESULTS

All eyes responded to the photochemical treatment with improvement in symptoms and signs of reduced inflammation. Epithelial healing was achieved in all cases. Antibiotic administration was necessary in two cases. One patient required a human amniotic membrane transplant.

CONCLUSIONS

This trial illustrates that photosensitization of riboflavin using UVA at 365 nm has the potential to induce healing in patients with microbial keratitis. The results from the treatment of these 16 patients with corneal ulcers indicate that UVA-riboflavin photochemical therapy merits a controlled study in order to assess its efficacy and safety compared to antibiotics.

In this study, we cloned and sequenced a DNA fragment from an ordered cosmid library of Helicobacter pylori NCTC 11638 which confers to a siderophore synthesis mutant of Escherichia coli (EB53 aroB hemA) the ability to grow on iron-restrictive media and to reduce ferric iron. Sequence analysis of the DNA fragment revealed the presence of an open reading frame with high homology to the ribA gene of Bacillus subtilis. This gene encodes a bifunctional enzyme with the activities of both 3,4-dihydroxy-2-butanone 4-phosphate (DHBP) synthase and GTP cyclohydrolase II, which catalyze two essential steps in riboflavin biosynthesis. Expression of the gene (designated ribBA) resulted in the formation of one translational product, which was able to complement both the ribA and the ribB mutation in E. coli. Expression of ribBA was iron regulated, as was suggested by the presence of a putative FUR box in its promotor region and as shown by RNA dot blot analysis. Furthermore, we showed that production of riboflavin in H. pylori cells is iron regulated. E. coli EB53 containing the plasmid with H. pylori ribBA excreted riboflavin in the culture medium, and this riboflavin excretion also appeared to be iron regulated. We postulate that the iron-regulated production of riboflavin and ferric-iron-reduction activity by E. coli EB53 transformed with the H. pylori ribBA gene is responsible for the survival of EB53 on iron-restrictive medium. Because disruption of ribBA in H. pylori eliminates its ferric-iron-reduction activity, we conclude that ribBA has an important role in ferric-iron reduction and iron acquisition by H. pylori.

Shigella spp. are the major cause of bacillary dysentery worldwide. The pathogenic process involves bacterial invasion and lysis of the phagocytic vacuole, followed by replication and movement within the cell cytoplasm and, ultimately, spread directly into adjacent cells. This study demonstrates that S. flexneri cytochrome bd expression is necessary for normal intracellular survival and virulence. Cytochrome bd is one of two terminal oxidases in the bacterial respiratory chain that reduce molecular oxygen to water, utilizing intermediates shuttled through the electron transport chain. S. flexneri mutants that contain a disruption in the cydC locus, which leads to defective cytochrome bd expression, or in the riboflavin (ribE) or ubiquinol-8 (ubiH) biosynthetic pathway, which leads to elevated cytochrome bd expression, were evaluated in intracellular survival and virulence assays. The cydC mutant formed significantly smaller plaques, had significantly decreased intracellular survival, and had a 100-fold increase in lethal dose for mice compared with the wild type. The ribE and ubiH mutants each formed significantly larger plaques and had a 10-fold decrease in lethal dose for mice compared with the wild type. The data indicate that expression of cytochrome bd is required for S. flexneri intracellular survival and virulence.

Despite its contribution to nutrient intake and status, consumption of milk and dairy products by children and adolescents in many countries has waned in recent decades, with a substantial proportion of youth failing to meet intake recommendations. Dairy products remain an important dietary source of multiple micronutrients, including calcium, phosphorus, magnesium, zinc, iodine, potassium, vitamin A, vitamin D, vitamin B12 , and riboflavin (vitamin B2 ). In addition, dairy products provide children with energy, high-quality protein, and essential and nonessential fatty acids. A review of evidence was conducted to evaluate associations between milk or dairy product intake and health outcomes in children and adolescents. Results suggest a neutral or inverse association between consumption of milk and dairy products in children and adolescents and indicators of adiposity, incidence of dental caries, and hypertension. Available data indicate that dairy products are important for linear growth and bone health during childhood. Additional research--in particular, controlled intervention trials and long-term prospective cohort studies--is warranted to better understand how dairy intake affects health outcomes in children and adolescents.

OBJECTIVE

To increase the stability of the cornea by artificial cross-linking (radiation or chemical agents) and to investigate a future therapy for keratoconus.

METHODS

The epithelium of enucleated porcine eyes was removed. Ten eyes in each of eight test groups were treated with UV light (lambda = 254 nm), 0.5% riboflavin and UV light (365 nm), blue light (436 nm) and sunlight, and the chemical agents glutaraldehyde (1% and 0.1%, 10 min) and Karnovsky's solution (0.1%, 10 min). Strips of 5 mm in width and 9 mm in length were cut from each cornea and the stress-strain behaviour of the strips was measured. For comparison, eight groups of ten untreated corneas each were measured by the same method.

RESULTS

Compared to untreated corneas riboflavin and UV irradiation as well as glutaraldehyde and Karnovsky's solution treatment resulted in significantly increased stiffness of the cornea (p < 0.05).

CONCLUSIONS

The biomechanical behaviour of the cornea can be altered by low-concentration glutaraldehyde, Karnovsky's solution, and by riboflavin and UV irradiation, which offers potential conservative treatment of keratoconus. To optimize this effect further investigation is necessary regarding the dose-effect relation and the in-vivo conditions.

OBJECTIVE

To assess the progression of keratoconus in patients treated with collagen cross-linking with riboflavin and ultraviolet A (UVA) irradiation.

METHODS

Thirty-eight eyes of 19 patients with progressive keratoconus were enrolled in a prospective comparative study. Average follow-up was 9 +/- 2 months (range: 5 to 12 months). The worse eye was treated with collagen cross-linking, and the fellow eye served as the control. Corneal epithelium was mechanically removed. Riboflavin 0.1% solution in dextran T-500 20% solution was applied every 2 to 3 minutes for 30 minutes throughout the irradiation. Ultraviolet A irradiation (370 nm) was performed using a commercially available UVA lamp for 30 minutes.

RESULTS

The group treated with collagen crosslinking demonstrated a mean decrease (less myopic) in spherical equivalent refraction and cylinder of 1.03 +/- 2.22 diopters (D) (range: -5.25 to +3.75 D) and 1.04 +/- 1.44 D (range: -2.00 to +4.00 D), respectively (P < .01), and an increase in uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA) of 0.06 +/- 0.05 (range: 0.00 to 0.20) and 0.10 +/- 0.14 (range: -0.10 to 0.34), respectively (P < .01). The maximal curvature decreased by 1.57 +/- 1.14 D (range: 0.00 to 3.90 D), and intraocular pressure increased by 2 +/- 2 mmHg (range: -1 to 6 mmHg), which was statistically significant. No statistical difference was noted regarding central corneal thickness (P = .06) and endothelial cell count (P = .07). The untreated group showed no statistical difference for any of the clinical parameters, apart from UCVA and BSCVA, which decreased by 0.08 +/- 0.12 (range: -0.40 to 0.10) and 0.06 +/- 0.09 (range: -0.20 to 0.10), respectively (P < .01).

CONCLUSIONS

Riboflavin/UVA collagen cross-linking appears to be efficacious in inhibiting the progression of keratoconus by reducing the corneal curvature, spherical equivalent refraction, and refractive cylinder in eyes with progressive keratoconus at average 9-month follow-up.

A systematic review was conducted to identify all studies that were published between 1988 and 2008 reporting micronutrient intakes of women in resource-poor settings. Inclusion criteria were study location (resource-poor), dietary assessment method (24-h recall, estimated/weighed record, or locally validated FFQ), energy and 1 or more micronutrient intakes reported (vitamin A, vitamin B-6, vitamin B-12, vitamin C, thiamin, riboflavin, niacin, folate, iron, or zinc), age range (15-50 y), sample size (≥30), and sex (female). Of the 1560 papers identified, 52 papers were included. Results showed that, except for vitamin A (29%), vitamin C (34%), and niacin (34%), the reported mean/median intakes in over 50% of studies were below the Estimated Average Requirement (EAR). Folate intake was most often below EAR (91% of studies). Regional differences were apparent for intakes of vitamins A, C, and B-6 and riboflavin; mean/median intakes in Latin America exceeded the EAR, whereas in Asia, reported mean/median intakes of vitamin C, vitamin A, and riboflavin were below the EAR in 47, 50, and 77% of the studies, respectively, as was the case for vitamin B-6 in 75% of the studies in Africa. These results suggest that inadequate intakes of multiple micronutrients are common among women living in resource-poor settings and emphasize the need for increased attention to the quality of women's diets. There is a need for more high-quality studies of women's micronutrient intakes.

OBJECTIVE

To report refractive, topographic, and biomechanical outcomes, efficiency, and safety of corneal collagen crosslinking (CXL) 1, 3, 6, and 12 months after treatment.

METHODS

National Reference Centre for Keratoconus, Bordeaux and Toulouse, France.

METHODS

Case series.

METHODS

This retrospective uncontrolled double-center study comprised eyes with progressive keratoconus. Uncorrected distance visual acuity, corrected distance visual acuity (CDVA), corneal pachymetry, endothelial cell count, and corneal hysteresis and corneal resistance factor were evaluated at baseline and at 1, 3, 6, and 12 months.

RESULTS

One hundred forty-two eyes were enrolled in the study. At 6 months, the CDVA had stabilized in 53 eyes (48.1%), improved in 36 eyes (32.7%), and decreased in 18 eyes (16.3%). At 12 months, the CDVA had stabilized in 31 eyes (47.6%), improved in 26 eyes (40.0%), and decreased in 8 eyes (12%). At 6 months, keratoconus progression had stopped in 51 eyes (49.03%) and the maximum keratometry (K) value had decreased by more than 1.0 diopter (D) in 37 eyes (35.5%); it continued to progress in 16 eyes (15.3%). At 12 months, keratoconus progression had stopped in 42 eyes (68.8%) and the maximum K value had decreased by more than 2.0 D in 13 eyes (21.3%). The complication rate with loss of vision was 3.5%.

CONCLUSIONS

Ultraviolet-A light associated with riboflavin CXL is an efficient procedure to stabilize and improve progressive keratoconus. The results reinforce previous studies highlighting the efficacy and safety of the procedure. A large prospective randomized clinical trial is needed.