Effect of Lifelong Exposure to Dietary Plant and Marine Sources of n-3 Polyunsaturated Fatty Acids on Morphologic and Gene Expression Biomarkers of Intestinal Health in Early Life

Altered intestinal health is also associated with the incidence and severity of many chronic inflammatory conditions, which could be attenuated via dietary n-3 PUFA interventions. However, little is known about the effect of lifelong exposure to n-3 PUFA from plant and marine sources (beginning in utero via the maternal diet) on early life biomarkers of intestinal health. Harems of C57Bl/6 mice were randomly assigned to one of three isocaloric AIN-93G modified diets differing in their fat sources consisting of the following: (i) 10% safflower oil (SO, enriched in n-6 PUFA), (ii) 3% flaxseed oil + 7% safflower oil (FX, plant-based n-3 PUFA-enriched diet), or (iii) 3% menhaden fish oil + 7% safflower oil (MO, marine-based n-3 PUFA-enriched diet). Mothers remained on these diets throughout pregnancy and offspring (n = 14/diet) continued on the same parental diet until termination at 3 weeks of age. In ileum, villi:crypt length ratios were increased in both the FX and MO dietary groups compared to SO (p < 0.05). Ileum mRNA expression of critical intestinal health biomarkers was increased by both n-3 PUFA-enriched diets including Relmβ and REG3γ compared to SO (p < 0.05), whereas only the FX diet increased mRNA expression of TFF3 and Muc2 (p < 0.05) and only the MO diet increased mRNA expression of ZO-1 (p < 0.05). In the proximal colon, both the FX and MO diets increased crypt lengths compared to SO (p < 0.05), whereas only the MO diet increased goblet cell numbers compared to SO (p < 0.05). Further, the MO diet increased proximal colon mRNA expression of Relmβ and REG3γ (p < 0.05) and both MO and FX increased mRNA expression of Muc2 compared to SO (p < 0.05). Collectively, these results demonstrate that lifelong exposure to dietary n-3 PUFA, beginning in utero, from both plant and marine sources, can support intestinal health development in early life. The differential effects between plant and marine sources warrants further investigation for optimizing health.

Parental Cooking Confidence is Associated with Children's Intake of Fish and Seafood

Purpose: Fish and seafood consumption by North American children is low. This is concerning, given the critical role of n-3 polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid), found in fish and seafood, in early development. This study aimed to determine whether parental factors related to fish and seafood consumption are associated with frequency of fish and seafood consumption in Canadian children.Methods: A subgroup of parents (n = 28) participating in the Guelph Family Health Study Pilot reported their perceptions and history of fish and seafood consumption, confidence in preparing fish and seafood dishes, and the frequency of intake for their children (n = 40).Results: This study found that 20% of children consumed one serving of saltwater fish, freshwater fish, or shellfish weekly and 63% consumed at least one type of fish or seafood monthly. Parental cooking confidence preparing fish and seafood was positively associated with at least monthly fish and seafood intake in children.Conclusions: These findings suggest that some children may have low intakes of fish and seafood due to a lack of parental cooking confidence when preparing fish and seafood dishes. Therefore, future research and interventions focused on addressing this barrier may aid in improving fish and seafood intake.

Effect of Short-Chain Fatty Acids on Inflammatory and Metabolic Function in an Obese Skeletal Muscle Cell Culture Model

The fermentation of non-digestible carbohydrates produces short-chain fatty acids (SCFAs), which have been shown to impact both skeletal muscle metabolic and inflammatory function; however, their effects within the obese skeletal muscle microenvironment are unknown. In this study, we developed a skeletal muscle in vitro model to mimic the critical features of the obese skeletal muscle microenvironment using L6 myotubes co-treated with 10 ng/mL lipopolysaccharide (LPS) and 500 µM palmitic acid (PA) for 24 h ± individual SCFAs, namely acetate, propionate and butyrate at 0.5 mM and 2.5 mM. At the lower SCFA concentration (0.5 mM), all three SCFA reduced the secreted protein level of RANTES, and only butyrate reduced IL-6 protein secretion and the intracellular protein levels of activated (i.e., ratio of phosphorylated-total) NFκB p65 and STAT3 (p < 0.05). Conversely, at the higher SCFA concentration (2.5 mM), individual SCFAs exerted different effects on inflammatory mediator secretion. Specifically, butyrate reduced IL-6, MCP-1 and RANTES secretion, propionate reduced IL-6 and RANTES, and acetate only reduced RANTES secretion (p < 0.05). All three SCFAs reduced intracellular protein levels of activated NFκB p65 and STAT3 (p < 0.05). Importantly, only the 2.5 mM SCFA concentration resulted in all three SCFAs increasing insulin-stimulated glucose uptake compared to control L6 myotube cultures (p < 0.05). Therefore, SCFAs exert differential effects on inflammatory mediator secretion in a cell culture model, recapitulating the obese skeletal muscle microenvironment; however, all three SCFAs exerted a beneficial metabolic effect only at a higher concentration via increasing insulin-stimulated glucose uptake, collectively exerting differing degrees of a beneficial effect on obesity-associated skeletal muscle dysfunction.

Sensory evaluations of a novel iron and zinc-enriched powder for the potential treatment and prevention of iron deficiency in women of reproductive age

Iron deficiency (ID) and ID with anaemia (IDA) are serious global health problems that disproportionately affect women aged 15-49 years. Although food fortification is one of the most effective and sustainable ways to combat nutritional deficiencies, iron remains one of the most difficult micronutrients to fortify, given its tendency to react strongly with food constituents. Therefore, it is important to assess the sensory properties of foods fortified with iron to determine the acceptability and palatability in target populations. We aimed to determine the palatability and acceptability of a novel iron and zinc-enriched powder fortified in tap water by conducting sensory evaluations in 35 women of reproductive age using a 9-point hedonic scale, where participants rated the sensory properties of six samples containing different amounts of the active or placebo powder. We found significant differences between samples reconstituted at 1, 2, and 3 g/L for sensory properties, including overall taste. Participants were found to be more willing to drink the mineral-enriched powder when prepared at the lowest concentration (1 g/L) compared to higher concentrations. Our results provide important insight into the sensory qualities of a novel formulation of an iron and zinc-enriched powder for at-home fortification and indicate consumer acceptability in reproductive-aged women, a key group at risk for ID/IDA. If found to improve iron status, novel treatments like this product will contribute to global efforts to develop safe, acceptable and sustainable interventions for ID and IDA.

Intakes of PUFA are Low in Preschool-aged Children in the Guelph Family Health Study Pilot Cohort

This study investigated intakes of total, n-3, and n-6 polyunsaturated fatty acids (PUFA) in 109 preschool-aged children who participated in the Guelph Family Health Study pilot. Intakes of total, n-3, and n-6 PUFA did not meet recommendations. This study highlights the need for additional monitoring and potential interventions to improve PUFA intake in preschool-aged children. Clinical trial #NCT02223234. Novelty: Canadian preschool-aged children are not consuming enough n-3 and n-6 polyunsaturated fatty acids.

Fish oil supplementation increases expression of mammary tumor apoptosis mediators and reduces inflammation in an obesity-associated HER-2 breast cancer model

Obesity is associated with inflammation and has been shown to increase breast cancer severity. The objective of this study was to examine the effect of fish oil (FO) supplementation in obesity-associated mammary tumorigenesis in the MMTV-neu(ndl)-YD5 mouse model of human epidermal growth factor receptor-2 positive BC. Female mice were fed one of three diets for 16 weeks: i) high fat diet [HF, % kacl: 41.2% lard, 18.7% corn oil (CO)], ii) an isocaloric HF plus menhaden FO diet (HF+FO, % kcal: 41.2 lard, 13.4% CO, 5.3% FO), iii) low fat diet (LF, % kcal: 4.7% lard, 6% CO). HF mice had increased body weight, visceral adipose weight and serum hormone concentrations (increased leptin and resistin; decreased adiponectin) versus LF, which was attenuated in the HF+FO group versus HF (P<.05). Compared to HF, tumor onset was delayed in HF+FO and LF mice (P<0.05). Compared to HF, HF+FO reduced mammary tumor multiplicity (-27%), tumor weight (-46%) and total tumor volume (-50%) (P<0.05). Additionally, HF+FO reduced mammary tumor multiplicity (-33%), tumor weight (-39%) and total tumor volume (-60%) versus LF. HF+FO improved mammary tumor apoptosis status with increased expression of pro-apoptotic Bad and decreased expression of anti-apoptotic Bcl-xLmediators versus HF (P<0.05). Additionally, HF+FO decreased tumor protein expression of activated Akt, NFκB p65 and STAT3, versus HF (P<0.05). Tumor mRNA expression of inflammatory mediators TNFα, IL-6 and leptin were reduced in HF+FO, whereas IL-10 expression was increased compared to HF (P<0.05). Collectively these results demonstrate the efficacy of FO supplementation for improving obesity-associated breast cancer outcomes.

Analysis of major fatty acids from matched plasma and serum samples reveals highly comparable absolute and relative levels

Measuring fatty acid (FA) levels in blood as a risk factor for chronic disease has been studied extensively. Previous research has used either plasma or serum samples to examine these associations. However, whether results from plasma and serum samples can be compared remains unclear, as differences in methodology related to the separation of plasma and serum from whole blood may impact FA levels. This study analyzed the individual FA content of matched plasma and serum samples in both absolute (μg/mL) and relative percent (%) composition. Analyses were performed using archived fasted morning samples from the Florey Adelaide Male Ageing Study (FAMAS). Matched plasma and serum samples were available from 98 male subjects aged 40-85. Total FA were analyzed by gas-liquid chromatography equipped with a flame ionization detector (GLC-FID). Analyses comprised of over 60 FA including major FA such as Palmitic Acid (PA), Palmitoleic acid (POA), Stearic Acid (SA), Oleic Acid (OA), Linoleic Acid (LNA), alpha-linolenic acid (ALA), Eicosapentaenoic acid (EPA), Arachidonic Acid (ARA), and Docosahexaenoic acid (DHA). Differences between groups was determined by t-test. Correlation and Bland-Altman analyses were also performed to examine the relationship between plasma and serum samples. There were no significant differences between major plasma and serum fatty acids expressed in μg/mL and relative % composition. Correlation analysis determined a strong and significantly positive association (r ≥ 0.65, p < 0.05) between major plasma and serum FA in absolute and relative terms. Bland-Altman analysis further supported the strong agreement between plasma and serum values in both absolute and relative terms. These findings demonstrate that studies reporting plasma or serum fatty acid analyzed by GLC-FID can be compared with one another.

Differentiating the biological effects of linoleic acid from arachidonic acid in health and disease

Dietary fatty acids are associated with the development of many chronic diseases, such as obesity, diabetes, cardiovascular disease, metabolic syndrome, and several cancers. This review explores the literature surrounding the combined and individual roles of n-6 PUFAs linoleic acid (LA) and arachidonic acid (AA) as they relate to immune and inflammatory response, cardiovascular health, liver health, and cancer. The evidence suggests that a pro-inflammatory view of LA and AA may be over simplified. Overall, this review highlights gaps in our understanding of the biological roles of LA, AA and their complex relationship with n-3 PUFA and the need for future studies that examine the roles of individual fatty acids, rather than groups.

Phase II studies of nebulised Arikace in CF patients with Pseudomonas aeruginosa infection

Rationale

Arikace is a liposomal amikacin preparation for aerosol delivery with potent Pseudomonas aeruginosa killing and prolonged lung deposition.

Objectives

To examine the safety and efficacy of 28 days of once-daily Arikace in cystic fibrosis (CF) patients chronically infected with P aeruginosa.

Methods

105 subjects were evaluated in double-blind, placebo-controlled studies. Subjects were randomised to once-daily Arikace (70, 140, 280 and 560 mg; n=7, 5, 21 and 36 subjects) or placebo (n=36) for 28 days. Primary outcomes included safety and tolerability. Secondary outcomes included lung function (forced expiratory volume at one second (FEV₁)), P aeruginosa density in sputum, and the Cystic Fibrosis Quality of Life Questionnaire—Revised (CFQ-R).

Results

The adverse event profile was similar among Arikace and placebo subjects. The relative change in FEV₁ was higher in the 560 mg dose group at day 28 (p=0.033) and at day 56 (28 days post-treatment, 0.093L±0.203 vs −0.032L±0.119; p=0.003) versus placebo. Sputum P aeruginosa density decreased >1 log in the 560 mg group versus placebo (days 14, 28 and 35; p=0.021). The Respiratory Domain of the CFQ-R increased by the Minimal Clinically Important Difference (MCID) in 67% of Arikace subjects (560 mg) versus 36% of placebo (p=0.006), and correlated with FEV₁ improvements at days 14, 28 and 42 (p<0.05). An open-label extension (560 mg Arikace) for 28 days followed by 56 days off over six cycles confirmed durable improvements in lung function and sputum P aeruginosa density (n=49).

Conclusions

Once-daily Arikace demonstrated acute tolerability, safety, biologic activity and efficacy in patients with CF with P aeruginosa infection.

Evolution of Pseudomonas aeruginosa virulence in infected patients revealed in a Dictyostelium discoideum host model

Pseudomonas aeruginosa can cause acute lung infections in intubated patients or chronic infections in patients with cystic fibrosis (CF). In both situations, P. aeruginosa accumulates specific mutations, in particular in the lasR quorum-sensing regulator gene. Using a Dictyostelium discoideum amoeba model, we assessed whether these mutations affect bacterial virulence. Among a collection of clinical isolates from 16 CF patients, initial isolates were fully virulent in 15 patients, but for late isolates collected several years later, virulence was decreased in eight patients. No significant correlation between genetic inactivation of lasR and decreased virulence was observed. Among strains isolated from ten colonized intubated patients, all initial isolates were fully virulent. Despite the accumulation of lasR-inactivating mutations in strains collected over a 3-week period, no decrease in virulence was observed in eight of 10 patients. In one intubated patient, the virulent initial strain was replaced a few days later with a different, less virulent, strain. We observed a gradual decrease in bacterial virulence in only one intubated patient. We conclude that adaptation of P. aeruginosa to chronically infected CF patients can lead to a slow and gradual loss of virulence, as measured in a Dictyostelium model system. However, loss of virulence is not caused predominantly by mutations in lasR. During short-term colonization of intubated patients for up to 20 days, a decrease in virulence was exceptional, despite the accumulation of lasR mutations.

Genetic adaptation of Pseudomonas aeruginosa to the airways of cystic fibrosis patients is catalyzed by hypermutation

In previous work (E. E. Smith, D. G. Buckley, Z. Wu, C. Saenphimmachack, L. R. Hoffman, D. A. D'Argenio, S. I. Miller, B. W. Ramsey, D. P. Speert, S. M. Moskowitz, J. L. Burns, R. Kaul, and M. V. Olson, Proc. Natl. Acad. Sci. USA 103:8487-8492, 2006) it was shown that Pseudomonas aeruginosa undergoes intense genetic adaptation during chronic respiratory infection (CRI) in cystic fibrosis (CF) patients. We used the same collection of isolates to explore the role of hypermutation in this process, since one of the hallmarks of CRI is the high prevalence of DNA mismatch repair (MMR) system-deficient mutator strains. The presence of mutations in 34 genes (many of them positively linked to adaptation in CF patients) in the study collection of 90 P. aeruginosa isolates obtained longitudinally from 29 CF patients was not homogeneous; on the contrary, mutations were significantly concentrated in the mutator lineages, which represented 17% of the isolates (87% MMR deficient). While sequential nonmutator lineages acquired a median of only 0.25 mutation per year of infection, mutator lineages accumulated more than 3 mutations per year. On the whole-genome scale, data for the first fully sequenced late CF isolate, which was also shown to be an MMR-deficient mutator, also support these findings. Moreover, for the first time the predicted amplification of mutator populations due to hitchhiking with adaptive mutations in the course of natural human infections is clearly documented. Interestingly, increased accumulation of mutations in mutator lineages was not a consequence of overrepresentation of mutations in genes involved in antimicrobial resistance, the only adaptive trait linked so far to hypermutation in CF patients, demonstrating that hypermutation also plays a major role in P. aeruginosa genome evolution and adaptation during CRI.

Covariates of tooth-brushing frequency in low-income African Americans from grades 5 to 8

PURPOSE

The purpose of this study was to examine tooth-brushing frequency in 575 urban and nearby suburban African American children as part of a comprehensive risk-reduction study for students at high risk for violence, drugs, school delinquency, and unsafe sexual behaviors to determine which covariates predicted tooth-brushing frequency.

METHODS

Students were surveyed 5 times, from the beginning of grade 5 and the end of each year through grade 8, and parents were surveyed at the beginning of grade 5. Peer influence, importance of being liked, self-esteem, attitudes towards tooth-brushing, oral health knowledge, self-efficacy, parental attitudes, and other covariates were examined for the ability to predict self-reporting of tooth-brushing frequency.

RESULTS

In the fifth grade, peer influence, the importance of being liked, and physical self-esteem were the significant predictors, and peer influence continued to predict tooth-brushing in the eighth grade. Oral health knowledge and parental influence were not significant.

CONCLUSION

Peer influence is an important factor in tooth-brushing behavior in metropolitan African American preadolescent children.

Insulin-like growth factor ligands, receptors, and binding proteins in cancer

This review aims to summarize experimental evidence supporting the role of the insulin-like growth factor (IGF) signalling system in the progression, maintenance, and treatment of cancer. These data implicate the IGF system as an important modifier of cancer cell proliferation, survival, growth, and treatment sensitivity. The role of the IGF system in cancer should be examined in the context of the extra-cellular and intra-cellular signalling networks, in particular: phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt/PKB), mammalian target of rapamycin (mTOR), and forkhead transcription factors (FOXO). This review highlights evidence derived from molecular structure and functional genetics with respect to how the extra-cellular components of the IGF system function normally, and their subsequent modifications in cancer. The therapeutic relevance of the research evidence described is also addressed, as the challenge is to apply this knowledge to human health.

Viscosity effect on the structural compactness of latex flocs formed under weak depletion attractions

Dilute aqueous dispersions of colloidal polystyrene latex spheres were flocculated by adding a nonadsorbing polymer sample, poly(acrylic acid). The structural compactness of the flocs thus formed was characterized in terms of their mass fractal dimension using the small-angle static light scattering technique. It was found that with low poly(acrylic acid) concentrations and thus weak depletion attraction forces, the dispersion medium viscosity had a marked effect on the floc structure. An increase in the viscosity led to formation of denser flocs. This was revealed in three sets of depletion flocculation experiments: (a) adjusting the background electrolyte concentration at a fixed level of poly(acrylic acid), (b) using water and 30% (w/w) glycerol as the respective solvents, and (c) inducing latex flocculation with two poly(acrylic acids) of different molecular weights at the respective critical polyacid concentrations. Direct force measurements were made with atomic force microscopy to isolate the influence of viscosity on floc structure from that of interparticle interaction energies. We conclude that the formation of denser flocs with increasing medium viscosity can be attributed to the reduced diffusivity of particles in the solution. The latter resulted in an enhanced rate of floc restructuring (through relaxation of attached particles) relative to floc growth.

Early pulmonary infection, inflammation, and clinical outcomes in infants with cystic fibrosis

A thorough understanding of the early natural history of cystic fibrosis (CF) lung disease is critical for the development of effective interventions in the youngest patients. We assessed the evolution of pulmonary infection, inflammation, and clinical course among 40 infants over a 2-year period through annual bronchoalveolar lavage (BAL) for culture and measurements of pro- and anti-inflammatory cytokines, semiannual infant pulmonary function testing, and quarterly clinical evaluations. Both the prevalence of CF pathogens and their density in BAL fluid increased with age. Infants had neutrophilic lower airway inflammation and elevated IL-8 concentrations independent of whether CF pathogens were recovered. Total leukocyte and neutrophil densities and IL-8 concentrations increased with density of CF pathogens in BAL fluid, whether the isolated organism was P. aeruginosa or another pathogen. IL-10 concentrations were similar in CF subjects and non-CF historical controls. Infants generally had suboptimal growth (low weight and height percentiles) and obstructive lung disease (decreased expiratory flows and air trapping). Subjects from whom CF pathogens were isolated at > 10(5) cfu/mL had the worst air trapping and lowest Brasfield chest X-ray scores. Our findings provide a foundation for future studies of early intervention in CF lung disease, including antimicrobial and anti-inflammatory therapy.

Cell survival and proliferation are modified by insulin-like growth factor 2 between days 9 and 10 of mouse gestation

The size of mammalian species involves the interaction of multiple genetic modifiers that control the timing and extent of growth mechanisms. Disruption of the paternal allele of the imprinted embryonic gene coding for insulin-like growth factor 2 (IGF2, Igf2+m/−p), results in viable mice that are 60% the weight of wild-type littermates. Differences in weight are first detected at embryonic day (E) 11, and the growth deficit is maintained throughout life. We report the mechanisms that account for this unusual phenotype. In order to quantify growth, we used novel methods to generate single cell suspensions of post-implantation mouse embryos. We were then able to quantify cell number, cell proliferation and cell death between E8.5 and E11.5 using flow cytometry. Determination of total embryo cell number also allowed us to time litters by a method other than by plugging. Wild-type and Igf2+m/−p embryos accumulated similar total cell numbers up to E9.25, but cell number began to diverge by around E9.5, with significant differences by E11 (75% of wild type). A relative increase in pyknotic nuclei, sub-GI cytometry counts and caspase activity, all indicative of cell death, occurred in Igf2+m/−p embryos at E9.25, reverting to wild-type levels by E9.75. This was followed at E9.75 by a significant reduction in the proportion of cells in S phase, quantified by S-phase cytometry counts and BrdU labelling. No significant differences in cell size were detected. We conclude that the majority of the cell number differences between wild-type and Igf2+m/−p mice can be accounted for by modification of cell survival and proliferation during the period (E9 to E10) of post-implantation development.

Serum and lower respiratory tract drug concentrations after tobramycin inhalation in young children with cystic fibrosis

OBJECTIVES

To assess the serum and lower respiratory tract tobramycin concentrations (C(T)) produced by a single dose of tobramycin for inhalation delivered by a nebulizer and a compressor in patients with cystic fibrosis (CF) 6 months to 6 years of age.

STUDY DESIGN

We performed a dose escalation study of serum C(T) measured before and 0.5, 1, 2, and 4 hours after a single dose of inhaled tobramycin, either 180 mg (10 patients) or 300 mg (19 patients). In a separate group of 12 patients, epithelial lining fluid (ELF) C(T) was measured by bronchoalveolar lavage 30 to 45 minutes after a 300-mg dose.

RESULTS

A 180-mg dose of inhaled tobramycin produced a mean peak serum C(T) of 0.5 microg/mL (SD 0.4; range, <0.2 to 1.4 microg/mL). A 300-mg dose produced a mean peak serum C(T) of 0.6 microg/mL (SD 0.5; range, <0.2 to 1.2 microg/mL). These peak values are well below the accepted maximum trough concentration with parenteral dosing (2 microg/mL). The target ELF C(T) was 20 microg/mL, 10-fold greater than the minimal inhibitory concentration for most Pseudomonas aeruginosa isolates from very young patients with CF (2 microg/mL). Mean ELF C(T) was 90 microg/mL (SD 54; range, 16 to 204 microg/mL) and exceeded the target concentration in 11 patients.

CONCLUSION

In patients with CF ages 6 months to 6 years, a single 300-mg dose of inhaled tobramycin appears to produce safe peak serum concentrations and drug concentrations in the bactericidal range in the lower respiratory tract.

Use of random amplified polymorphic DNA PCR to examine epidemiology of Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans from patients with cystic fibrosis

Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans have been increasingly recognized as a cause of respiratory tract colonization in cystic fibrosis (CF). Although both organisms have been associated with progressive deterioration of pulmonary function, demonstration of causality is lacking. To examine the molecular epidemiology of S. maltophilia and A. xylosoxidans in CF, isolates from patients monitored for up to 2 years were fingerprinted using a PCR-based randomly amplified polymorphic DNA (RAPD-PCR) method. Sixty-one of 69 CF centers screened had 183 S. maltophilia culture-positive patients, and 46 centers had 92 A. xylosoxidans-positive patients. At least one isolate from each patient was genotyped, and patients with > or =10 positive cultures (12 S. maltophilia cultures, 15 A. xylosoxidans cultures) had serial isolates genotyped. In addition, centers with multiple culture-positive patients were examined for evidence of shared clones. There were no instances of shared genotypes among different CF centers. Some patients demonstrated isolates with a single genotype throughout the observation period, and others had intervening or sequential genotypes. At the six centers with multiple S. maltophilia culture-positive patients and the seven centers with multiple A. xylosoxidans-positive patients, there were three and five instances of shared genotypes, respectively. The majority of shared isolates were from pairs who were siblings or otherwise epidemiologically linked. These findings suggest RAPD-PCR typing can distinguish unique CF isolates of S. maltophilia and A. xylosoxidans, person-to-person transmission may occur, there are not a small number of clones infecting CF airways, and patients with long-term colonization may either have a persistent organism or may acquire additional organisms over time.

A view through the clouds of imprinting

The purpose of this review is to examine whether our current knowledge of the higher order control of gene expression and nuclear organization can help us understand the mechanisms of genomic imprinting. Imprinting involves the inheritance of a silenced allele of a gene through either a paternal or maternal germline. We have approached the problem of imprinting using a model based on the dynamic attachment of chromatin loops to immobilized RNA polymerases and control elements. We have combined the information from different experimental approaches, examining primarily the IGF2-H19 locus, in an attempt to simplify the complexity of the imprinting data that has accumulated. It is hoped that a unified model may generate predictions amenable to experimental testing and contribute to the interpretation of future experiments.

A rare continual flowering strategy and its influence on offspring quality in a gynodioecious plant

The majority of angiosperms have a single annual bout of reproduction; species that flower continually throughout the year are rare. Ochradenus baccatus is a gynodioecious, desert shrub whose principal flowering period is associated with the winter rains, although large individuals also remain in flower during the hot, dry summer. The goal of this study was to examine the reproductive consequences of continual flowering in a large population of O. baccatus in Israel. Over the two years of this study, 60% of individuals flowered continuously. The number of fruit and seeds per fruit were greater in winter. Winter seeds were ∼12% heavier than summer seeds and had significantly higher germination rates (80 vs. 60%, respectively). Although summer seeds were smaller and less likely to germinate, we propose that the benefit derived from their production lies in their ability to capitalize on the first winter rains. These early rain events provide a head start on establishment and growth in the hostile desert environment. Plants that delay reproduction until the onset of rains risk having their offspring face the dry conditions of spring and summer.

Young at heart: understanding the unique psychosocial adjustment of young implantable cardioverter defibrillator recipients

This article reviews the data related to psychosocial adjustment of young ICD recipients, postulates theories to explain potential adjustment difficulties to ICD therapy experienced by younger recipients, and suggests clinical management techniques for addressing the unique psychosocial concerns of young ICD recipients. Studies of young ICD recipients suggest that a wide range of psychosocial adjustment issues are prominent in the post-ICD implantation period and that the issues may be different from older ICD recipients. The disability-stress-coping model and the transactional-stress-coping model are postulated as explanations for the unique adjustment concerns of children and adolescents with ICDs. Social comparison theory is also applied to the concerns of young adults with ICDs such that they often lack same age peers to compare experiences with cardiac difficulties. Brief, clinic-based interventions by health care providers, like a screening and referral heuristic and an "ICD Buddy" system, are suggested to increase effective coping and decrease social isolation for young ICD recipients.

Comparison of two commercial systems (Vitek and MicroScan-WalkAway) for antimicrobial susceptibility testing of Pseudomonas aeruginosa isolates from cystic fibrosis patients

Antimicrobial susceptibility testing of cystic fibrosis (CF) isolates of Pseudomonas aeruginosa is difficult because the organisms are often mucoid and slow-growing. This study of 498 CF strains examined the correlation of results derived from two commonly used commercial systems (Vitek, MicroScan-WalkAway) with a reference method for 10 antimicrobials. Correlation to reference results was unacceptably low for all agents and both commercial systems had a high rate of very major (false-susceptible) errors. Although mucoid strains produced a 4.8% greater intermethod error, it was not markedly different than non-mucoid strains for the Vitek System. Overall, these tested commercial systems performed poorly for CF isolates in contrast to earlier reported, high correlations with the reference methods (broth microdilution frozen panels and agar dilution) of the National Committee for Clinical Laboratory Standards, the standardized disk diffusion test, and the Etest (AB BIODISK, Solna, Sweden).

Sputum induction as a research tool for sampling the airways of subjects with cystic fibrosis

BACKGROUND

Sputum induction (SI) has proved to be a reliable non-invasive tool for sampling inflammatory airway contents in asthma, with distinct advantages over collection of expectorated sputum (ES) and bronchoalveolar lavage (BAL). A study was undertaken to evaluate the safety of SI and to assess if it might be an equally valuable outcome tool in patients with cystic fibrosis (CF).

METHODS

The safety of the procedure was examined and sample volume, cell counts, cytokine concentrations, and bacterial culture results obtained by SI, spontaneous ES, and fibreoptic bronchoscopy were compared in 10 adults with CF.

RESULTS

SI was well tolerated and was preferred to BAL by all subjects. The mean (SE) sample volume obtained by SI was significantly greater than ES (6.74 (1.46) ml v 1.85 (0.33) ml, p = 0.005). There was no significant difference in the number of cells per ml of sample collected. There was a difference in the mean (SD) percentage of non-epithelial, non-squamous cells collected (67 (28)%, 86 (21)%, and 99 (1)% for ES, SI, and BAL, respectively). These percentage counts were different between ES and both SI and BAL (p=0.03 and p=0.006, respectively). Cell differential counts (excluding squamous cells) from all collection methods were similar (mean (SD) 84 (9)%, 87 (7)%, and 88 (11)% polymorphonuclear cells for ES, SI, and BAL, respectively). The concentrations of interleukin (IL)-8 and tumour necrosis factor (TNF)-alpha were the same in all three samples when corrected for dilution using urea concentration. The test specific detection rate for recovery of bacteriological pathogens was 79% for SI, 76% for ES, and 73% for BAL.

CONCLUSION

SI offers safety advantages over BAL and may be a more representative airway outcome measurement in patients with CF.

Longitudinal assessment of Pseudomonas aeruginosa in young children with cystic fibrosis

Pseudomonas aeruginosa lung infection is an important cause of morbidity and mortality in cystic fibrosis (CF). Longitudinal assessment of the phenotypic changes in P. aeruginosa isolated from young children with CF is lacking. This study investigated genotypic and phenotypic changes in P. aeruginosa from oropharynx (OP) and bronchoalveolar lavage fluid (BALF) in a cohort of 40 CF patients during the first 3 years of life; antibody response was also examined. A high degree of genotypic variability was identified, and each patient had unique genotypes. Early isolates had a phenotype distinct from those of usual CF isolates: generally nonmucoid and antibiotic susceptible. Genotype and phenotype correlated between OP and BALF isolates. As determined by culture, 72.5% of patients demonstrated P. aeruginosa during their first 3 years. On the basis of combined culture and serologic results, 97.5% of patients had evidence of infection by age 3 years, which suggests that P. aeruginosa infection occurs early in CF and may be intermittent or undetectable by culture.

Transcytosis of gastrointestinal epithelial cells by Escherichia coli K1

Escherichia coli K1 is an important neonatal pathogen that is usually transferred from maternal to infant gastrointestinal tract at the time of parturition. Approximately 20% of neonates are colonized, and a proportion of colonized infants goes on to have systemic infection. Entry into the bloodstream from the gastrointestinal tract is hypothesized to occur via epithelial cell invasion. Invasion of multiple epithelial cell lines was studied using gentamicin protection assays and transcytosis of polarized monolayers. Electron microscopy was used to confirm cellular invasion. Cell lines used include two human gastrointestinal lines, Caco-2 and T84; a human respiratory cell line, A549; a human laryngeal cell line, HEp-2; and a canine kidney cell line, MDCK. A virulent E. coli K1 strain, RS218, readily invaded HEp-2, A549, and T84 cell lines in gentamicin protection assays, but was less invasive into MDCK and Caco-2 cells. RS218 also demonstrated transcytosis of both T84 and Caco-2 cells. Four clinical isolates of E. coli K1 demonstrated levels of transcytosis of T84 cells similar to RS218. Caco-2 invasiveness correlated with length of time in tissue culture with maximum invasiveness demonstrated at 11 d in culture, when cells were polarized and differentiated.

Identification and detection of Stenotrophomonas maltophilia by rRNA-directed PCR

Stenotrophomonas maltophilia has recently emerged as an important nosocomial pathogen in immunocompromised patients, in transplant recipients, and in persons with cystic fibrosis (CF). While this organism is nonpathogenic in healthy individuals, it is increasingly associated with morbidity and mortality in susceptible populations. Recent studies have indicated that for approximately 10% of CF patients with moderate lung disease, S. maltophilia can be cultured from respiratory tract secretions. Identification of S. maltophilia can be problematic, and analysis of isolates from the Burkholderia cepacia Research Laboratory and Repository showed that several isolates presumptively identified as B. cepacia by clinical microbiology laboratories were in fact S. maltophilia. To overcome the problems associated with definitive identification, we developed species-specific PCR (SS-PCR) primers, designated SM1 and SM4, directed to the 23S rRNA gene, and tested their utility to accurately identify S. maltophilia directly from sputum. The SS-PCR was developed and tested against a panel of 112 S. maltophilia isolates collected from diverse geographic locations. To test for specificity, 43 isolates from 17 different species were analyzed. PCR with the SM1-SM4 primer pair and isolated genomic DNA as a template resulted in amplification of a band from all S. maltophilia isolates and was uniformly negative for all other species tested, yielding a sensitivity and a specificity of 100% for the SS-PCR. The utility of the SS-PCR to directly identify S. maltophilia in sputum was examined. Thirteen expectorated sputum samples from CF patients were analyzed by SS-PCR. Three samples were PCR positive, in complete concordance with the conventional laboratory culture. Thus, we have developed an SS-PCR protocol that can rapidly and accurately identify S. maltophilia isolates and which can be used for the direct detection of this organism in CF patient sputum.

Factor analysis of the Condom Use Self-Efficacy Scale among multicultural college students

The Condom Use Self-Efficacy Scale (CUSES) was administered to 447 multicultural college students. The sample consisted of 63.5% Hispanic/Latino, 17.1% African-American, 13.7% Caucasian, 4.1% other and 1.6% Asian students. The obtained scores were subjected to a principal components factor analysis with a Varimax rotation. An item designation criteria was used and three distinct factors were extracted: (1) 'Appropriation', (2) 'Sexually Transmitted Diseases' and (3) 'Partners' Disapproval'. Comparisons to the only other published factor analysis of the CUSES are made. Implications for future research using the CUSES to design AIDS education curricula for multicultural college students are discussed.

Comparison of agar diffusion methodologies for antimicrobial susceptibility testing of Pseudomonas aeruginosa isolates from cystic fibrosis patients

Pseudomonas aeruginosa is the most common pathogen infecting the lungs of patients with cystic fibrosis (CF). Improved antimicrobial chemotherapy has significantly increased the life expectancy of these patients. However, accurate susceptibility testing of P. aeruginosa isolates from CF sputum may be difficult because the organisms are often mucoid and slow growing. This study of 597 CF isolates of P. aeruginosa examined the correlation of disk diffusion and Etest (AB BIODISK, Solna, Sweden) results with a reference broth microdilution method. The rates of interpretive errors for 12 commonly used antipseudomonal antimicrobials were determined. The disk diffusion method correlated well (zone diameter versus MIC) for all of the agents tested. However, for mucoid isolates, correlation coefficients (r values) for piperacillin, piperacillin-tazobactam, and meropenem were <0.80. The Etest correlation with reference broth microdilution results (MIC versus MIC) was acceptable for all of the agents tested, for both mucoid and nonmucoid isolates. Category interpretation errors were similar for the disk diffusion and Etest methods with 0.4 and 0.1%, respectively, very major errors (false susceptibility) and 1.1 and 2.2% major errors (false resistance). Overall, both agar diffusion methods appear to be broadly acceptable for routine clinical use in susceptibility testing of CF isolates of P. aeruginosa.

Aminoglycoside-resistance mechanisms for cystic fibrosis Pseudomonas aeruginosa isolates are unchanged by long-term, intermittent, inhaled tobramycin treatment

Aminoglycoside-resistance mechanisms were characterized in Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients during a recent clinical trial of inhaled tobramycin. Impermeability, in which bacteria have reduced susceptibility to all aminoglycosides, was the predominant mode of resistance in isolates obtained both before and after 6 months of cyclic treatment with tobramycin or placebo administered by aerosol. Enzymatic resistance mechanisms were found in fewer than 10% of resistant isolates. P. aeruginosa from individual patients could be grouped on the basis of genetic relatedness. When enzymatic resistance was involved, all isolates in a group had elevated tobramycin MICs. When impermeability occurred, MICs of a genotypic group varied from susceptible to resistant. These findings suggest that impermeability resistance occurs in only a fraction of the P. aeruginosa population in lungs of persons with CF and that this form of resistance arises by a process involving multiple small changes in MIC.

Activities of tobramycin and six other antibiotics against Pseudomonas aeruginosa isolates from patients with cystic fibrosis

The in vitro activity of tobramycin was compared with those of six other antimicrobial agents against 1,240 Pseudomonas aeruginosa isolates collected from 508 patients with cystic fibrosis during pretreatment visits as part of the phase III clinical trials of tobramycin solution for inhalation. The tobramycin MIC at which 50% of isolates are inhibited (MIC(50)) and MIC(90) were 1 and 8 microg/ml, respectively. Tobramycin was the most active drug tested and also showed good activity against isolates resistant to multiple antibiotics. The isolates were less frequently resistant to tobramycin (5.4%) than to ceftazidime (11.1%), aztreonam (11.9%), amikacin (13.1%), ticarcillin (16.7%), gentamicin (19.3%), or ciprofloxacin (20.7%). For all antibiotics tested, nonmucoid isolates were more resistant than mucoid isolates. Of 56 isolates for which the tobramycin MIC was > or = 16 microg/ml and that were investigated for resistance mechanisms, only 7 (12.5%) were shown to possess known aminoglycoside-modifying enzymes; the remaining were presumably resistant by an incompletely understood mechanism often referred to as "impermeability."

Specific lipopolysaccharide found in cystic fibrosis airway Pseudomonas aeruginosa

Cystic fibrosis (CF) patients develop chronic airway infections with Pseudomonas aeruginosa (PA). Pseudomonas aeruginosa synthesized lipopolysaccharide (LPS) with a variety of penta- and hexa-acylated lipid A structures under different environmental conditions. CF patient PA synthesized LPS with specific lipid A structures indicating unique recognition of the CF airway environment. CF-specific lipid A forms containing palmitate and aminoarabinose were associated with resistance to cationic antimicrobial peptides and increased inflammatory responses, indicating that they are likely to be involved in airway disease.

Fifteen years of experience with bacterial meningitis

BACKGROUND

Introduction of Haemophilus influenzae type b (Hib) vaccines has dramatically altered the epidemiology of bacterial meningitis in children. The goal of this study was to describe these changes in a pediatric teaching hospital.

METHODS

Patient charts at Children's Hospital and Regional Medical Center, Seattle, were identified by diagnosis codes and reviewed retrospectively. The 1981 to 1995 time period was chosen to incorporate three distinct 5-year periods: before the use of unconjugated Hib vaccine; between the unconjugated and conjugate vaccines; and after the conjugate vaccines were available for routine immunization of infants.

RESULTS

Bacterial meningitis was identified in 806 cases. In 13 premature infant cases Escherichia coli was most frequently isolated (6 cases). Group B Streptococcus, E. coli and Listeria monocytogenes were the most common pathogens in 87 neonatal cases. The most common pathogens in 706 cases of childhood meningitis were H. influenzae, Streptococcus pneumoniae and Neisseria meningitidis. H. influenzae was the most common pathogen in the first two time periods (73 and 69% of childhood cases, respectively), but not so in the third period (16%).

CONCLUSIONS

A changing pattern in childhood meningitis was observed during the study period. H. influenzae cases dramatically declined, altering the relative proportions of other pathogens, S. pneumoniae and N. meningitidis. However, the number of cases caused by these latter pathogens remained steady.

Evaluation of reference dilution test methods for antimicrobial susceptibility testing of Pseudomonas aeruginosa strains isolated from patients with cystic fibrosis

The development of multidrug-resistant Pseudomonas aeruginosa in patients with cystic fibrosis (CF) is most likely a consequence of increasing life expectancy and more prolonged exposure to antibiotics. The optimal method for antibiotic susceptibility testing of CF strains, particularly mucoid P. aeruginosa strains, is unknown. Antimicrobial susceptibilities of 48 CF strains (25 mucoid) and 50 non-CF strains to 12 anti-Pseudomonas agents were tested by both agar dilution and commercially custom-prepared broth microdilution plates (PML Microbiologicals, Portland, Oreg.) in three laboratories simultaneously to determine if broth microdilution could substitute for agar dilution as the reference method in subsequent studies. Comparison of MICs generated by agar dilution and broth microdilution demonstrated correlation coefficients (r) exceeding 0.85 for all agents tested; correlation was excellent for aminoglycosides (r >/= 0.92) and very good for beta-lactam agents including agents paired with a beta-lactamase inhibitor (r >/= 0.87) and for ciprofloxacin (r = 0.86). Correlation was not improved by 48-h readings, but correlation between 24- and 48-h readings ranged between 0.91 and 0.98 for both methods. Interlaboratory variations were minimal, as the percentage of acceptable variations was 94% for both methods, and serious discords were infrequent (<2% of comparisons). However, CF strains were more likely to have serious discords than were non-CF strains (P < 0. 0001), although mucoid strains were not more likely to have serious discords than were nonmucoid strains. In this study, MICs determined by custom-prepared broth microdilution compared favorably with MICs determined by agar dilution. Thus, this broth microdilution assay can serve as a reference method and facilitate future studies to determine the optimal method for antibiotic susceptibility testing of CF strains.

Calcineurin is required for skeletal muscle hypertrophy

Molecular signaling pathways linking increases in skeletal muscle usage to alterations in muscle size have not been identified. In the present study, we tested the hypothesis that calcineurin, a calcium-regulated phosphatase recently implicated in the signaling of some forms of cardiomyopathic growth, is required to induce skeletal muscle hypertrophy and muscle fiber type conversions associated with functional overload in vivo. Administration of the specific calcineurin inhibitors cyclosporin (CsA) or FK506 to mice, for which the fast plantaris muscle was overloaded for 1-4 weeks, prevented the rapid doubling of mass and individual fiber size and the 4-20-fold increase in the number of slow fibers that characterize this condition. CsA treatment influenced the expression of muscle myofibrillar protein genes in a way reflective of fiber phenotype transformations but only in the long term of the overload condition, suggesting that the control of this growth response by calcineurin is not limited to the transcriptional activation of these muscle-specific genes. Clinically, these results provide insight to the post-surgical muscle wasting and weakness observed in recovering transplant recipients administered therapeutic dosages of these immunosuppressants.

Effect of chronic intermittent administration of inhaled tobramycin on respiratory microbial flora in patients with cystic fibrosis

Pseudomonas aeruginosa endobronchial infection causes significant morbidity and mortality among cystic fibrosis patients. Microbiology results from two multicenter, double-blind, placebo-controlled trials of inhaled tobramycin in cystic fibrosis were monitored for longitudinal changes in sputum microbial flora, antibiotic susceptibility, and selection of P. aeruginosa isolates with decreased tobramycin susceptibility. Clinical response was examined to determine whether current susceptibility standards are applicable to aerosolized administration. Treatment with inhaled tobramycin did not increase isolation of Burkholderia cepacia, Stenotrophomonas maltophilia, or Alcaligenes xylosoxidans; however, isolation of Candida albicans and Aspergillus species did increase. Although P. aeruginosa tobramycin susceptibility decreased in the tobramycin group compared with that in the placebo group, there was no evidence of selection for the most resistant isolates to become most prevalent. The definition of resistance for parenteral administration does not apply to inhaled tobramycin: too few patients had P. aeruginosa with a tobramycin MIC >/=16 microgram/mL to define a new break point on the basis of clinical response.

Comparison of isolation media for recovery of Burkholderia cepacia complex from respiratory secretions of patients with cystic fibrosis

Burkholderia cepacia selective agar (BCSA) has previously been devised for isolation of B. cepacia from respiratory secretions of patients with cystic fibrosis and tested under research laboratory conditions. Here we describe a study in which BCSA, oxidation-fermentation polymyxin bacitracin lactose agar (OFPBL), and Pseudomonas cepacia agar (PCA) were compared in routine culture procedures for the ability to grow B. cepacia and inhibit other organisms. Three hundred twenty-eight specimens from 209 patients at two pediatric centers and 328 specimens from 109 adults were tested. Plates were inoculated, incubated, and read for quality and quantity of growth at 24, 48, and 72 h. Five (1.5%) specimens from 4 (1.9%) children and 75 (22.9%) specimens from 16 (14.7%) adults grew B. cepacia complex. At 24, 48, and 72 h, BCSA achieved 43, 93, and 100% detection, respectively; OFPBL achieved 26, 84, and 96%, respectively; and PCA achieved 33, 74, and 84% detection, respectively. Quality was assessed as pinpoint or good growth. At 24 h, most cultures growing B. cepacia complex had pinpoint colonies. By 48 and 72 h, 48 and 69% of B. cepacia complex cultures, respectively, had good growth on BCSA, while on OFPBL 19 and 30%, respectively, had good growth and on PCA 11 and 18%, respectively, had good growth. BCSA was superior to OFPBL and PCA in suppressing organisms other than B. cepacia complex; 40 non-B. cepacia complex organisms were isolated from BCSA, 263 were isolated from OFPBL, and 116 were isolated from PCA. We conclude that BCSA is superior to OFPBL and PCA in its ability to support the growth of B. cepacia complex and to suppress other respiratory organisms.

Microbiology of sputum from patients at cystic fibrosis centers in the United States

During a phase III national collaborative study of aerosolized tobramycin (1 July 1995 through 30 September 1996), the microbiology of specimens from 595 patients at 69 cystic fibrosis (CF) centers was examined. Samples from three screening visits were processed in a single laboratory by means of standardized techniques for identification and susceptibility testing. From 1,753 pretreatment specimens, 5,128 pathogens were isolated (average, 2.9/specimen). Of the 3,936 Pseudomonas aeruginosa isolates, 56.7% were mucoid. The specimens of 125 patients (21.0%) yielded tobramycin-resistant P. aeruginosa (213 isolates); 61 (10.3%), Stenotrophomonas maltophilia; and 52 (8.7%), Alcaligenes xylosoxidans. Isolation of Burkholderia cepacia was an exclusion criterion. Only visit 3 sputum samples were cultured for gram-positive organisms and fungi (n = 465 patients); samples from 201 patients (43.2%) yielded Staphylococcus aureus (18.8% of isolates were oxacillin-resistant), and those from 114 (24.5%) yielded an Aspergillus species. Compared with the Cystic Fibrosis Foundation Patient Registry, the current study identified many more patients colonized with S. maltophilia, A. xylosoxidans, Aspergillus species, and oxacillin-resistant S. aureus, suggesting the utility of standardized processing of CF specimens.