Effects of Red Beetroot Juice and Inorganic Nitrate Supplementation on Oral Bacteria and Nitric Oxide Metabolites in Middle-Aged/Older Adults with Overweight and Obesity

Objectives

Dietary inorganic nitrate from foods such as red beetroot juice (RBJ) can contribute to nitric oxide (NO) bioavailability through the enterosalivary nitrate-nitrite-NO pathway. A critical step in this pathway is the reduction of nitrate to nitrite by oral bacteria. We investigated the effects of inorganic nitrate supplementation, as RBJ or placebo + potassium nitrate (PBO+NIT), on the oral microbiota, and its relationship with saliva and plasma NO metabolites and vascular endothelial function.

Methods

In a randomized, double-blind, placebo-controlled trial, we measured the abundance of oral nitrate-reducing bacteria in saliva samples from 15 middle-aged/older adults with overweight and obesity using 16 rRNA sequencing. We also assessed the relationship of oral nitrate-reducing bacteria with the physiological responses to acute (4 hours) and chronic (4 weeks) RBJ, PBO+NIT, nitrate-free RBJ, and placebo supplementation via measurement of saliva and plasma nitrate/nitrite (NOx), plasma nitrite levels, and reactive hyperemia index (RHI).

Results

A significant decrease in the alpha diversity metric, Pileou's Evenness, was detected after chronic consumption of PBO+NIT (0.69 ± 0.05 at week 0 vs. 0.65 ± 0.05 at week 4; P < 0.05), while there was a trend for a decline following RBJ consumption (0.69 ± 0.05 at week 0 vs. 0.65 ± 0.05 at week 4; P = 0.08). No significant differences in abundance of nitrate-reducing bacteria were observed after chronic supplementation, although abundance of the species Neisseria subflava was trending toward an increase in the RBJ group (10.8% at week 0 vs. 12.2% at week 4; P = 0.07). Plasma and saliva NOx increased from baseline and remained elevated for the 4-hour testing period after acute and chronic RBJ and PBO+NIT supplementation (all P < 0.05), while plasma nitrite only peaked at 2 hours in the RBJ group after acute supplementation and was significantly higher than PBO+NIT group (P < 0.01). RHI change from baseline to 4 hours was positively correlated with total abundance of nitrate-reducing species after chronic RBJ supplementation (r = 0.5; P = 0.05).

Conclusions

Acute and chronic RBJ and PBO+NIT supplementation increases NO metabolites and may alter the oral microbiota to favorably affect vascular endothelial function in middle-aged/older adults with overweight and obesity.

Funding Sources

NIFA, USDA.

Evaluating the Impact of an Aronia Berry Dietary Supplement on Vascular Endothelial Function and the Gut Microbiota in Healthy Middle-Aged/Older Adults: Study Protocol

Objectives

Aging is the primary risk factor for cardiovascular disease (CVD) largely due to vascular endothelial dysfunction, an initiating step in the development of atherosclerosis. The gut microbiota has emerged as an important regulator of cardiovascular health. Aronia berries are rich in polyphenols such as anthocyanins, proanthocyanidins, and phenolic acids. These compounds, and metabolites resulting from gut microbial and phase II metabolism, have been shown to improve endothelial function. The primary objective of this study is to assess the dose-dependent efficacy of an aronia berry full spectrum dietary supplement to improve vascular endothelial function in middle-aged/older men and postmenopausal women. A secondary goal is to determine whether aronia full spectrum modulation of the gut microbiota is associated with improvements in vascular endothelial function.

Methods

Healthy men and postmenopausal women (n = 28) aged 45–75 years are being recruited for this randomized, double-blind, placebo-controlled, crossover trial. In random order, participants take a placebo, 500 mg aronia full spectrum, or 1000 mg aronia full spectrum daily for a 6-week period. Each treatment period is separated by a 6-week washout period. The primary outcome is reactive hyperemia index (RHI), a validated measure of vascular endothelial function assessed using peripheral arterial tonometry. Secondary outcome measures include analysis of the gut microbiota in stool samples, hemodynamic parameters including blood pressure and augmentation index, arterial stiffness, and blood biomarkers of cardiovascular and metabolic health including blood lipids, hemoglobin a1c, oxidized LDL, and adhesion molecules. Other outcome measures will include plasma, fecal, and urine polyphenol metabolites. Gut microbial populations will be statistically compared with RHI.

Results

To date, a total of 22 individuals (11 men/11 women) have been enrolled in the trial and randomized to their intervention order. Of these, 3 have completed the study, 1 was lost to follow-up, and 18 are currently enrolled.

Conclusions

We hypothesize that this aronia berry dietary supplement will dose-dependently improve vascular endothelial function in healthy middle-aged/older adults, and that improvements will be linked to modulation of the gut microbiota.

Funding Sources

Naturex.

Amounts and Botanical Diversity of Dietary Fruits and Vegetables Affect Distinctly the Human Gut Microbiome

Objectives

While increasing fruit and vegetable (FV) intake is a near-universal recommendation for improved health outcomes, information on dietary FV amount and diversity impact on health biomarkers is scarce. FV are a major dietary source of gut microbiota (GM) accessible carbohydrates and phytochemicals, however, most studies have focused on single food items or their extracted components, with few holistic studies available. Here, two separate randomized dietary interventions were used to assess the impact of low vs high FV intake and low vs high botanical diversity on GM profiles in healthy adults. We hypothesized that increasing FV would result in beneficial modulations to GM with further increases benefits in those consuming FV from diverse botanical families.

Methods

Study 1 was a crossover design with, 11 males randomized to starting diets of low FV (L) or high FV (H) over 9 days. Stool samples were obtained at day 0, 3, 6 and 9 of each treatment period. In Study 2, 21 individuals were provided a low FV (L) lead-in diet for 4 days and then randomly assigned to a high FV diet with either low (LB; 11 families) or high botanical diversity (HB; 24 families) for an additional 4 days. Stool was collected at baseline, and after each diet intervention. GM was analyzed using 16S rRNA sequencing performed on an Illumina MiSeq. The Mothur pipeline was used for preliminary data analysis, followed by statistical analyses in PAST.

Results

In Study 1, the L treatment resulted in minimal microbiota alterations, while a significant increase in Bacteroidetes and decrease in Firmicutes (which peaked at day 6) was observed in the H group. Intriguingly, the L group experienced a short-term increase in Bifidobacterium and Lactobacillus, and both treatments incurred significant increases in Bacteroides and Akkermansia and a decline of Faecalibacterium. In study 2 the transition from low to high FV resulted in similar trends than in Study 1. However, the HB treatment resulted in a more diverse GM, characterized by increased relative abundances of beneficial Firmicutes (Lachnospiraceae, Faecalibacterium and Clostridium XIVa).

Conclusions

Our results suggest that both amounts of FV consumed and botanical diversity modulate the GM. Determining better FV combinations from a GM perspective thus appears as a possible task for future research.

Funding Sources

Colorado Agriculture Experiment Station.

Impact of Acute and Chronic Red Beetroot Juice Consumption on Postprandial Endothelial Function and Levels of Nitrate/Nitrite in Plasma and Saliva (P06-113-19)

Objectives

High-fat meal (HFM) consumption has been shown to impair postprandial endothelial function. Red beetroot juice (RBJ) contains polyphenols, betalains, carotenoids, ascorbic acid, and inorganic nitrate, and has been shown to improve endothelial function. This study investigated the acute and chronic effects of RBJ and its bioactive components on postprandial endothelial function. We hypothesized that a HFM would impair postprandial endothelial function, and that RBJ would attenuate this, in part, through increased circulating nitrate/nitrite (NOx) levels.

Methods

A 4-period randomized, double-blind, placebo-controlled crossover clinical trial was conducted. Fifteen overweight and obese middle-aged/older men and postmenopausal women underwent baseline (T0) assessment of endothelial function (via reactive hyperemia index, RHI) and collection of blood and saliva. Participants consumed one of the following 70 mL treatments (acute exposure): 1) RBJ, 2) nitrate-free RBJ (NF-RBJ), 3) placebo + nitrate (PBO + NIT), and 4) placebo (PBO), followed by a HFM. RHI was measured at 4 hours (T4) post-HFM, and blood and saliva were collected at 1 hour (T1), 2 hours (T2), and T4. Participants then consumed treatments daily for 4 weeks (chronic exposure), and all assessments were repeated before/after the HFM but without consuming treatments.

Results

No significant time or treatment effects were observed for RHI. Following acute and chronic exposure to RBJ and PBO + NIT, plasma NOx levels were higher at T0 (chronic only), T1, T2, and T4 compared to PBO and NF-RBJ (P < 0.001). After chronic exposure to RBJ, saliva NOx levels were higher at T0, T1, T2, and T4 compared to PBO and NF-RBJ (P < 0.001). Saliva NOx levels for PBO + NIT were higher than both PBO and NF-RBJ at T0 (P < 0.001), but only higher than NF-RBJ at T1 (P = 0.02), and higher than PBO at T4 (P = 0.02). Additionally, there was a time*treatment interaction for plasma and saliva NOx levels following 4 weeks of daily exposure to RBJ and PBO + NIT (P < 0.001).

Conclusions

The preliminary results of this study suggest that HFM consumption does not significantly impair postprandial endothelial function in this population. In addition, acute and chronic RBJ exposure does not significantly improve endothelial function despite increases in plasma and saliva NOx.

Funding Sources

Colorado Agricultural Experiment Station, NIFA, USDA.

Cardiometabolic Effects of a Gut Microbial Metabolite of Tryptophan in Western Diet-fed Mice (P21-025-19)

Objectives

Our lab has recently established that the gut microbiota regulates obesity-related vascular dysfunction. However, the specific mechanisms by which the gut microbiota regulates host physiology remain obscure. Indoles are products of bacterial tryptophan metabolism and have been shown to exert various physiological effects on the host. In the current study, we examine the effects of indole-3-propionic acid (IPA) on cardiometabolic outcomes in western diet-fed mice.

Methods

Male C57BL/6 mice were fed either and standard diet (SD) or western diet (WD) for 5-months (mo). Two additional groups were fed the same diets and supplemented with IPA (SD + IPA and WD + IPA) in autoclaved drinking water (0.1 mg/ml) during the dietary intervention. After 5mo, arterial stiffness was assessed by aortic pulse wave velocity (aPWV). Intestinal permeability was measured with FITC-dextran. Glucose tolerance was assessed after a 6 hour fast followed by intraperitoneal injection of 2 g/kg glucose solution.

Results

Both WD-fed groups displayed significantly higher body weight than SD and SD + IPA (P < 0.05) with no effect of IPA supplementation. aPWV was significantly higher in WD and WD + IPA compared to SD (485.7 ± 6.7 & 492.8 ± 8.6 vs 436.9 ± 7.0 cm/s, P < 0.05), whereas the SD + IPA was not significantly different than either WD-fed groups (468.1 ± 6.6, P > 0.05). Supplementation with IPA in the SD + IPA group significantly increased glucose AUC compared to SD mice (1763.3 ± 92.0 vs 1397.6 ± 64.0, P < 0.05) and no significant differences were observed with either WD or WD + IPA groups (1623.5 ± 77.3 & 1658.4 ± 88.4, P > 0.05). No significant differences were observed between groups with regard to intestinal permeability.

Conclusions

In the current study, supplementation with IPA in WD-fed mice did not affect arterial stiffness, glucose tolerance, or intestinal permeability. Future analyses will determine other cardiometabolic effects and characterize the gut microbiota.

Funding Sources

Colorado Agricultural Experimental Station Research Grant #COL00766.

Suppression of the gut microbiome ameliorates age-related arterial dysfunction and oxidative stress in mice

KEY POINTS

Age-related arterial dysfunction, characterized by oxidative stress- and inflammation-mediated endothelial dysfunction and arterial stiffening, is the primary risk factor for cardiovascular diseases. To investigate whether age-related changes in the gut microbiome may mediate arterial dysfunction, we suppressed gut microbiota in young and old mice with a cocktail of broad-spectrum, poorly-absorbed antibiotics in drinking water for 3-4 weeks. In old mice, antibiotic treatment reversed endothelial dysfunction and arterial stiffening and attenuated vascular oxidative stress and inflammation. To provide insight into age-related changes in gut microbiota that may underlie these observations, we show that ageing altered the abundance of microbial taxa associated with gut dysbiosis and increased plasma levels of the adverse gut-derived metabolite trimethylamine N-oxide. The results of the present study provide the first proof-of-concept evidence that the gut microbiome is an important mediator of age-related arterial dysfunction and therefore may be a promising therapeutic target for preserving arterial function with ageing, thereby reducing the risk of cardiovascular diseases.

ABSTRACT

Oxidative stress-mediated arterial dysfunction (e.g. endothelial dysfunction and large elastic artery stiffening) is the primary mechanism driving age-related cardiovascular diseases. Accumulating evidence suggests the gut microbiome modulates host physiology because dysregulation ('gut dysbiosis') has systemic consequences, including promotion of oxidative stress. The present study aimed to determine whether the gut microbiome modulates arterial function with ageing. We measured arterial function in young and older mice after 3-4 weeks of treatment with broad-spectrum, poorly-absorbed antibiotics to suppress the gut microbiome. To identify potential mechanistic links between the gut microbiome and age-related arterial dysfunction, we sequenced microbiota from young and older mice and measured plasma levels of the adverse gut-derived metabolite trimethylamine N-oxide (TMAO). In old mice, antibiotics reversed endothelial dysfunction [area-under-the-curve carotid artery dilatation to acetylcholine in young: 345 ± 16 AU vs. old control (OC): 220 ± 34 AU, P < 0.01; vs. old antibiotic-treated (OA): 334 ± 15 AU; P < 0.01 vs. OC] and arterial stiffening (aortic pulse wave velocity in young: 3.62 ± 0.15 m  s-1  vs. OC: 4.43 ± 0.38 m  s-1 ; vs. OA: 3.52 ± 0.35 m  s-1 ; P = 0.03). These improvements were accompanied by lower oxidative stress and greater antioxidant enzyme expression. Ageing altered the abundance of gut microbial taxa associated with gut dysbiosis. Lastly, plasma TMAO was higher with ageing (young: 2.6 ± 0.4 μmol  L-1   vs. OC: 7.2 ± 2.0 μmol  L-1 ; P < 0.0001) and suppressed by antibiotic treatment (OA: 1.2 ± 0.2 μmol  L-1 ; P < 0.0001 vs. OC). The results of the present study provide the first evidence for the gut microbiome being an important mediator of age-related arterial dysfunction and oxidative stress and suggest that therapeutic strategies targeting gut microbiome health may hold promise for preserving arterial function and reducing cardiovascular risk with ageing in humans.

The gut microbiota in infants of obese mothers increases inflammation and susceptibility to NAFLD

Maternal obesity is associated with increased risk for offspring obesity and non-alcoholic fatty liver disease (NAFLD), but the causal drivers of this association are unclear. Early colonization of the infant gut by microbes plays a critical role in establishing immunity and metabolic function. Here, we compare germ-free mice colonized with stool microbes (MB) from 2-week-old infants born to obese (Inf-ObMB) or normal-weight (Inf-NWMB) mothers. Inf-ObMB-colonized mice demonstrate increased hepatic gene expression for endoplasmic reticulum stress and innate immunity together with histological signs of periportal inflammation, a histological pattern more commonly reported in pediatric cases of NAFLD. Inf-ObMB mice show increased intestinal permeability, reduced macrophage phagocytosis, and dampened cytokine production suggestive of impaired macrophage function. Furthermore, exposure to a Western-style diet in Inf-ObMB mice promotes excess weight gain and accelerates NAFLD. Overall, these results provide functional evidence supporting a causative role of maternal obesity-associated infant dysbiosis in childhood obesity and NAFLD.

Abstract 165: Role of the Gut Microbiome in Obesity-Related Vascular Dysfunction

Vascular dysfunction, characterized by arterial stiffness and endothelial dysfunction, represents an important link between obesity and cardiovascular disease. Deleterious changes to the gut microbiome, termed dysbiosis, are associated with obesity and may contribute to the development of vascular dysfunction by promoting systemic and arterial inflammation. We tested the hypothesis that antibiotic treatment in diet-induced obese mice would improve vascular function by suppressing potentially harmful gut-derived bacterial products to reduce dysbiosis-related inflammation. Male C57BL/6 mice were fed either a standard diet (SD) or Western diet (WD) for 5 months. Obese WD-fed mice were then randomized to receive 8 weeks of antibiotic treatment via drinking water. Arterial stiffness was measured via in vivo aortic pulse wave velocity and endothelial function assessed via ex vivo pressure myography in isolated mesenteric arteries. Plasma and arterial tissue samples were collected for measures of endotoxemia and inflammation and fecal samples were collected for microbial sequencing. Our results showed that mice fed a WD for 5 months had significantly higher body weight and arterial stiffness compared to SD. Antibiotic treatment significantly reduced arterial stiffness in WD-fed mice without affecting body weight. Endothelial function was impaired in WD-fed mice, whereas WD-Abx mice had similar endothelial function to SD-fed mice. Plasma levels of the pro-inflammatory cytokine IL-6 and endotoxemia marker LPS binding protein (LBP) were significantly increased in WD vs SD, but reduced in WD-Abx vs WD. Gut microbial suppression with antibiotic treatment was confirmed using quantitative PCR and ongoing analyses are being conducted to determine specific diet-induced changes to the composition of the gut microbiome. Overall, our results support the hypothesis that gut dysbiosis contributes the development of vascular dysfunction in obesity and provide evidence that a gut-targeted therapy can improve endothelial function and arterial stiffness in diet-induced obese mice. Future studies will further examine the mechanisms involved in, and help identify potential therapeutic targets for, obesity-related vascular dysfunction.

Alterations in human milk leptin and insulin are associated with early changes in the infant intestinal microbiome

BACKGROUND

Increased maternal body mass index (BMI) is a robust risk factor for later pediatric obesity. Accumulating evidence suggests that human milk (HM) may attenuate the transfer of obesity from mother to offspring, potentially through its effects on early development of the infant microbiome.

OBJECTIVES

Our objective was to identify early differences in intestinal microbiota in a cohort of breastfeeding infants born to obese compared with normal-weight (NW) mothers. We also investigated relations between HM hormones (leptin and insulin) and both the taxonomic and functional potentials of the infant microbiome.

DESIGN

Clinical data and infant stool and fasting HM samples were collected from 18 NW [prepregnancy BMI (in kg/m(2)) <24.0] and 12 obese (prepregnancy BMI >30.0) mothers and their exclusively breastfed infants at 2 wk postpartum. Infant body composition at 2 wk was determined by air-displacement plethysmography. Infant gastrointestinal microbes were estimated by using 16S amplicon and whole-genome sequencing. HM insulin and leptin were determined by ELISA; short-chain fatty acids (SCFAs) were measured in stool samples by using gas chromatography. Power was set at 80%.

RESULTS

Infants born to obese mothers were exposed to 2-fold higher HM insulin and leptin concentrations (P < 0.01) and showed a significant reduction in the early pioneering bacteria Gammaproteobacteria (P = 0.03) and exhibited a trend for elevated total SCFA content (P < 0.06). Independent of maternal prepregnancy BMI, HM insulin was positively associated with both microbial taxonomic diversity (P = 0.03) and Gammaproteobacteria (e.g., Enterobacteriaceae; P = 0.04) and was negatively associated with Lactobacillales (e.g., Streptococcaceae; P = 0.05). Metagenomic analysis showed that HM leptin and insulin were associated with decreased bacterial proteases, which are implicated in intestinal permeability, and reduced concentrations of pyruvate kinase, a biomarker of pediatric gastrointestinal inflammation.

CONCLUSION

Our results indicate that, although maternal obesity may adversely affect the early infant intestinal microbiome, HM insulin and leptin are independently associated with beneficial microbial metabolic pathways predicted to increase intestinal barrier function and reduce intestinal inflammation. This trial was registered at clinicaltrials.gov as NCT01693406.

Fecal metabolome and microflora differences between colorectal cancer patients and healthy adults

11050

Background: High throughput genomic technologies such as 454 pyrosequencing and metabolomics platforms are now available to explore the relationships between gastrointestinal microflora, metabolism and colorectal cancer (CRC). Recent efforts to characterize the colorectal cancer microbiome have led to the identification of numerous bacteria whose presence or absence is associated with diseased tissue. Methods: Stool samples were collected from 10 healthy adults and 11 colorectal cancer patients prior to surgery at the University of Colorado Health-Poudre Valley Hospital in Fort Collins, CO. Fecal samples were processed for isolation of microbial DNA and sequenced using the 454 pyrosequencing platform. Metabolites were extracted using acidified water for short chain fatty acids (SCFA) and 3:2:2 isopropanol:acetonitrile:water to obtain global metabolite profiles utilizing Gas Chromatography-Mass Spectrometry (GC-MS). Results: There were no significant differences in the overall microbial community structure associated with disease state, but several bacterial genera, particularly butyrate-producing species, were under-represented in the CRC samples, while a mucin-degrading species, Akkermansia muciniphila, was about 4-fold higher in CRC (p<0.01). Consequently, the chemoprotective SCFA, butyrate, was significantly lower in CRC samples than in those from healthy adults (p<0.0001) and GC-MS profiling revealed that there were higher levels of amino acids in stool samples from CRC patients and higher poly and monounsaturated fatty acids in stool from healthy adults (p<0.01). Conclusions: This systems biology approach may allow us to identify functional groups of gastrointestinal bacteria and their associated metabolites as novel therapeutic and chemopreventive targets. The Colorado Agricultural Experiment Station, Shipley Foundation and the NIH R03CA150070 supported this work.

Increasing dietary rice bran consumption for colorectal cancer prevention and control

1558

Background: Emerging evidence supports that dietary rice bran (RB) exhibits colorectal cancer (CRC) control and prevention activity, yet a significant knowledge gap exists for feasibility of increased RB intake in humans. BENEFIT (Bran Enriching Nutritional Eating For Intestinal health Trial), is a community-academic partnership for dietary chemoprevention research. Our main objectives were to pilot the feasibility of increased RB consumption in healthy adults, with and without a history of CRC, and to examine changes in gut microflora and fecal metabolite profiles following RB consumption. Methods: Seven meals and six snacks were developed for inclusion of dietary RB (30g/day). A total of 15 adults (7 non-cancer and 8 CRC survivors) completed the randomized-controlled, dietary intervention trial. Participants were blinded to their study group (placebo-control or RB) and consumed one study meal and snack daily for 28 days. Blood, urine, saliva and stool samples were collected at baseline, 2-week, and 4-week timepoints for metabolomic and microbiome analyses. Participants recorded weekly 3-day dietary food logs. Results: Adding RB (30g) into prepared foods provided 4-8% daily caloric intake with 95.5% intervention compliance. Inclusion of RB or control diet intervention in our non-cancer cohort did not result in a major shift of the fecal microbiome after 2- and 4-weeks. For CRC survivors, we observed that 19% of the total variation in the fecal microbiome was due to the rice bran intervention. At the genus level, we saw changes in Bacteroides, Bifidobacterium, and Ruminococcus. Principal Components Analyses of fecal metabolome detected using liquid-chromatography mass spectrometry revealed 16% variation between time points and 8% variation when comparing RB and control groups at 4 weeks. Candidate metabolites from ~50 features will be determined by spectral libraries and database matches. Conclusions: The accessibility, affordability, and availability of RB support the global public health impact potential for novel RB “phytochemical teamwork” based CRC control and prevention strategies. These findings warrant further evaluation of increased RB intake in a larger cohort for CRC control and prevention.

Driven dynamics and rotary echo of a qubit tunably coupled to a harmonic oscillator

We have investigated the driven dynamics of a superconducting flux qubit that is tunably coupled to a microwave resonator. We find that the qubit experiences an oscillating field mediated by off-resonant driving of the resonator, leading to strong modifications of the qubit Rabi frequency. This opens an additional noise channel, and we find that low-frequency noise in the coupling parameter causes a reduction of the coherence time during driven evolution. The noise can be mitigated with the rotary-echo pulse sequence, which, for driven systems, is analogous to the Hahn-echo sequence.

Down regulation of virulence factors of Pseudomonas aeruginosa by salicylic acid attenuates its virulence on Arabidopsis thaliana and Caenorhabditis elegans

Salicylic acid (SA) is a phenolic metabolite produced by plants and is known to play an important role in several physiological processes, such as the induction of plant defense responses against pathogen attack. Here, using the Arabidopsis thaliana-Pseudomonas aeruginosa pathosystem, we provide evidence that SA acts directly on the pathogen, down regulating fitness and virulence factor production of the bacteria. Pseudomonas aeruginosa PA14 showed reduced attachment and biofilm formation on the roots of the Arabidopsis mutants lox2 and cpr5-2, which produce elevated amounts of SA, as well as on wild-type Arabidopsis plants primed with exogenous SA, a treatment known to enhance endogenous SA concentration. Salicylic acid at a concentration that did not inhibit PA14 growth was sufficient to significantly affect the ability of the bacteria to attach and form biofilm communities on abiotic surfaces. Furthermore, SA down regulated three known virulence factors of PA14: pyocyanin, protease, and elastase. Interestingly, P. aeruginosa produced more pyocyanin when infiltrated into leaves of the Arabidopsis transgenic line NahG, which accumulates less SA than wild-type plants. This finding suggests that endogenous SA plays a role in down regulating the synthesis and secretion of pyocyanin in vivo. To further test if SA directly affects the virulence of P. aeruginosa, we used the Caenorhabditis elegans-P. aeruginosa infection model. The addition of SA to P. aeruginosa lawns significantly diminished the bacterium's ability to kill the worms, without affecting the accumulation of bacteria inside the nematodes' guts, suggesting that SA negatively affects factors that influence the virulence of P. aeruginosa. We employed microarray technology to identify SA target genes. These analyses showed that SA treatment affected expression of 331 genes. It selectively repressed transcription of exoproteins and other virulence factors, while it had no effect on expression of housekeeping genes. Our results indicate that in addition to its role as a signal molecule in plant defense responses, SA works as an anti-infective compound by affecting the physiology of P. aeruginosa and ultimately attenuating its virulence.

Plant models for animal pathogenesis

Several bacteria that are pathogenic to animals also infect plants. Mechanistic studies have proven that some human/animal pathogenic bacteria employ a similar subset of virulence determinants to elicit disease in animals, invertebrates and plants. Therefore, the results of plant infection studies are relevant to animal pathogenesis. This discovery has resulted in the development of convenient, cost-effective, and reliable plant infection models to study the molecular basis of infection by animal pathogens. Plant infection models provide a number of advantages in the study of animal pathogenesis. Using a plant model, mutations in animal pathogenic bacteria can easily be screened for putative virulence factors, a process which if done using existing animal infection models would be time-consuming and tedious. High-throughput screening of plants also provides the potential for unravelling the mechanisms by which plants resist animal pathogenic bacteria, and provides a means to discover novel therapeutic agents such as antibiotics and anti-infective compounds. In this review, we describe the developing technique of using plants as a model system to study Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus pathogenesis, and discuss ways to use this new technology against disease warfare and other types of bioterrorism.

Leukemia inhibitory factor is synthesized and released by human eosinophils and modulates activation state and chemotaxis

BACKGROUND

The cytokine leukemia inhibitory factor (LIF) is known to be produced by both inflamed peripheral autonomic nerves and several cell types involved in the regulation of the immune response. We have recently demonstrated that several structural cell types in human airways produce LIF in response to inflammatory stimuli and that LIF augments contractile responses to tachykinins in airway explants. Because the eosinophil is a major effector cell in asthma and often found adjacent to the nerves, we hypothesized that eosinophils produce LIF and that LIF primes and upregulates eosinophil recruitment and function, allowing bidirectional neuroimmune interactions and augmentation of eosinophil-mediated injury.

OBJECTIVE

The purpose of this study was to demonstrate that human eosinophils synthesize and release LIF, to determine the effects of LIF on eosinophil functions (ie, chemotaxis, granule protein release, expression of the activation marker CD69, and apoptosis), and to compare serum LIF levels between atopic and nonatopic individuals.

METHODS

Reverse-transcription PCR, ELISA, immunocytochemistry, chemotaxis assay, and flow cytometry were used.

RESULTS

Peripheral blood eosinophils express LIF and messenger RNA for LIF and LIF receptor. Serum LIF levels were higher in atopic patients with mild asthma than in nonatopic normal donors. Eosinophils from nonatopic donors were stimulated by calcium ionophore to release small amounts of LIF (from almost none to 5.3 +/- 1.8 pg/10(6) cells). Eosinophils from atopic donors showed a 10-fold increase (from 45.1 +/- 38.7 pg/106 cells to 414.5 +/- 189.9 pg/10(6) cells). Preincubation of eosinophils with LIF increased eosinophil peroxidase release 4-fold. LIF was not chemotactic for eosinophils but augmented chemotaxis mediated by substance P by 82% and by platelet-activating factor by 31%. LIF did not effect eosinophil apoptosis but increased CD69 expression.

CONCLUSION

LIF has proinflammatory roles in eosinophil-dependent airway disorders.

Linkage of microsatellites to the AGXT gene on chromosome 2q37.3 and their role in prenatal diagnosis of primary hyperoxaluria type 1

Defects in the AGXT gene mapped to chromosome 2q37.3 cause primary hyperoxaluria type 1 (PH1), one of the inherited disorders of endogenous oxalate overproduction. In order to identify diagnostically useful linkage markers in this region of chromosome 2 we have typed three microsatellite loci mapping to the q37 region of chromosome 2 in 192 individuals from 30 families. They were additionally studied for mutations and polymorphisms in the AGXT gene. Maximum lod scores of 29.1, 22.8 and 15.8 were obtained for D2S140, D2S125 and D2S395 respectively at recombination fractions (theta) of 0.001, 0.015 and 0.02. Confidence intervals for recombination as determined by the 'lod-1 rule' were 0.015, 0.05 and 0.06. Three recombinants were identified between AGXT and D2S125/D2S395, whereas no recombination between AGXT and D2S140 was observed. These data allow the calculation of the risk of incorrect prenatal diagnosis of PH1 based solely on linkage analysis with these extragenic markers.

A semiautomated alanine:glyoxylate aminotransferase assay for the tissue diagnosis of primary hyperoxaluria type 1

We have developed a sensitive assay for the measurement of alanine:glyoxylate aminotransferase (EC 2.6.1.44) activity in human liver. The assay is partly automated, and takes into consideration the sensitivity of the reaction to pH and to glyoxylate concentration. It is less subject to interference from other enzymes utilizing glyoxylate and to chemical interference from glyoxylate itself and can therefore be used without correction for cross-over by glutamate:glyoxylate aminotranferase (EC 2.6.1.4). The assay allows clear discrimination between normal and affected livers and is sufficiently sensitive to measure enzyme activity in fetal liver samples. Enzyme activity ranged from 17.9 to 38.5 mumol/h/mg protein in control livers (n = 9) and 0.8 to 9.5 mumol/h/mg protein in 30 of 39 hyperoxaluric patients studied. Normal alanine:glyoxylate aminotransferase activity (from 22.8 to 45.5 mumol/h/mg protein) allowed exclusion of primary hyperoxaluria type 1 in the other nine hyperoxaluric patients.

Adenosine A3 receptor expression and function in eosinophils

The A3 adenosine receptor is widely expressed in human tissues with the most abundant expression in the lung and liver, but the predominant cellular localization and functions of this receptor in humans are unknown. Since adenosine influences the activation of circulating and resident inflammatory cells within the lung and leads to exaggerated airway narrowing in individuals with inflammatory airway disorders, we hypothesized that A3 receptor gene expression is localized to inflammatory cells and that gene expression is upregulated in airway inflammation. Lung and airway tissue were obtained at thoracotomy from nonsmoking subjects and subjects with inflammatory airway disorders associated with tobacco smoke or asthma. In situ hybridization identified A3 receptors in mesenchymal cells and eosinophils within the lamina propria of the airways and the adventitia of blood vessels, but not in mast cells. A3 receptor transcripts were highly expressed in peripheral blood eosinophils purified from atopic donors (6.36 +/- 0.60 pg/microg total RNA) in comparison with neutrophils (0.26 +/- 0.06 pg/microg) or mononuclear cells (0.9 +/- 0.15 pg/microg). Mean A3 receptor transcript abundance was greater in lung tissue from subjects with airway inflammation (0.33 +/- 0.04 pg/microg total RNA) than in normal lung (0.24 +/- 0.03 pg/microg total RNA, P = 0.035). The A3 receptor agonist N6-(4-amino-3-iodobenzyl)adenosine dose-dependently inhibited platelet activating factor-induced eosinophil chemotaxis to a maximum of 41%. This inhibitory effect was completely abolished by addition of the A3 receptor selective antagonist 3-(3-iodo-4-aminobenzyl)-8-(4-oxyacetate)phenyl-1-propylxanthine. We conclude that A3 receptors are primarily expressed on eosinophils in human lung, where they mediate inhibition of eosinophil chemotaxis. Specific A3 receptor ligands may be useful agents in the treatment of eosinophil-dependent diseases such as asthma and rhinitis.

Characterization of an RNA-dependent RNA polymerase activity associated with La France isometric virus

Purified preparations of La France isometric virus (LIV), an unclassified, double-stranded RNA (dsRNA) virus of Agaricus bisporus, were associated with an RNA-dependent RNA polymerase (RDRP) activity. RDRP activity cosedimented with the 36-nm isometric particles and genomic dsRNAs of LIV during rate-zonal centrifugation in sucrose density gradients, suggesting that the enzyme is a constituent of the virion. Enzyme activity was maximal in the presence of all four nucleotides, a reducing agent (dithiothreitol or beta-mercaptoethanol), and Mg2+ and was resistant to inhibitors of DNA-dependent RNA polymerases (actinomycin D, alpha-amanitin, and rifampin). The radiolabeled enzyme reaction products were predominantly (95%) single-stranded RNA (ssRNA) as determined by cellulose column chromatography and ionic-strength-dependent sensitivity to hydrolysis by RNase A. Three major size classes of ssRNA transcripts of 0.95, 1.3, and 1.8 kb were detected by agarose gel electrophoresis, although the transcripts hybridized to all nine of the virion-associated dsRNAs. The RNA products synthesized in vitro appeared to be of a single polarity, as they hybridized to an ssDNA corresponding to one strand of a genomic dsRNA and not to the complementary strand. Similarly, reverse transcription-PCR with total cellular ssRNA as a template and strand-specific primers targeting a genomic dsRNA during synthesis of cDNA suggested that only the coding strand was transcribed in vivo. Our data indicate that the RDRP activity associated with virions of LIV is probably a transcriptase engaged in the synthesis of ssRNA transcripts corresponding to each of the virion-associated dsRNAs.

Fire Studies in Mallee (Eucalyptus Spp.) Communities of Western New South Wales: Reptile and Beetle Populations in Sites of Differing Fire History

Reptile and terrestrial beetle populations were sampled within adjoining mallee communities of similar botanical composition, but differing in fire history and vegetation structure. Studies were aimed at determining whether there were any major differences between faunal communities in sites with different fire histories. While the number of beetle species captured was significantly higher in the two most recently burnt sites, overall abundance of beetles did not differ significantly between various fire histories. Captures of Carenurn interiove were highest in a site burnt seven years prior to the study whereas captures of Tvichocarenum sp. were most common in the two most recently burnt areas. The number of reptile species captured did not differ significantly between sites but the relative abundance of nocturnal and diurnal reptiles was found to be significantly related to time since last fire. The number of geckos captured at the oldest fire site (burnt 18 years earlier) were significantly fewer than at the more recently burnt sites whereas captures of diurnal lizards did not differ. These patterns of reptile abundance are consistent with those found in other fire studies undertaken in similar habitats. This preliminary study confirms that both reptiles and beetles may be usefully incorporated in future management systems designed to monitor biological diversity in mallee ecosystems. Key words: fire, mallee, porcupine grass, nocturnal and diurnal reptiles and beetles

The genetics of asthma

In this paper we have summarized the evidence for a genetic contribution to asthma as well as the recent advances in techniques for identifying the location and function of genes that cause complex diseases. We have also reviewed how these techniques have been applied to the study of asthma and allergy. It is likely that rapid additional advances will be made over the next several years. There are ongoing genome-wide searches to identify additional genes. An understanding of the genetic variation that predisposes people to asthma and the atopic diseases could open a variety of potential diagnostic and therapeutic avenues. Firstly, the identification of the specific mutations that alter the immune response could provide targets for gene therapy. However, in the short run this is unlikely because the risks and costs associated with gene therapy do not presently justify application to alleviate the relatively nonlethal manifestations of allergic diseases. The second potential avenue will be in the development of specific pharmacologic therapy. For example, if variants of the IL-4 gene with enhanced function or of the IFN-gamma gene that have deficient function are identified as causative factors, drug development could be directed toward specific modulators of their effects. However, it is possible that redundancy in the immune and inflammatory responses, coupled with the likelihood of multiple gene involvement, will make such targeting fruitless or dangerous. The third consequence of identifying genetic variants predisposing to asthma and allergy is the possibility of screening. This is perhaps the most likely beneficial outcome of the present search for atopy genes. Recent studies suggest that the clinical onset of atopic diseases can be modified by preventing exposure to cigarette smoke and highly allergenic proteins in the first few years of life (188). At present the power of such studies is limited by the inability to predict those at risk with any certainty. Genetic screening of children born to atopic parents will allow more precise identification of those carrying atopy genes, and this could allow a focused attempt at environmental modification. In the short run this will allow the design of much more powerful prospective studies of prophylaxis, and in the long run screening may prove an effective strategy for asthma prevention.

Substance P (NK1)- and neurokinin A (NK2)-receptor gene expression in inflammatory airway diseases

The tachykinin neuropeptides substance P and neurokinin (NK) A have been postulated to participate in the inflammatory reaction in airways of smokers and asthmatics. We have examined the hypothesis that the expression of one or more of the three cloned tachykinin receptors (NK1, NK2, and NK3) is increased in inflammatory airway disorders, which could result in augmentation of the effect of released tachykinin neuropeptides. NK1 receptor and NK2 receptor but not NK3-receptor mRNA were detected by ribonuclease protection assay in RNA from both cartilaginous and membranous bronchi and subpleural lung. In lung samples containing membranous airways, NK2-receptor mRNA expression was increased fourfold in asthmatics compared with nonsmoking controls, whereas NK1-receptor mRNA levels were similar in the two groups. NK1- and NK2-receptor mRNA expression was increased twofold in smokers without airflow obstruction compared with nonsmokers, whereas NK1-receptor mRNA expression was significantly lower in patients with chronic obstructive pulmonary disease compared with smoking controls. In situ hybridization indicated NK1-receptor mRNA was expressed in submucosal glands and airway epithelial cells, whereas NK2-receptor and NK3-receptor mRNA were not detected. These observations have implications for the pathophysiology and treatment of both asthma and tobacco smoke-induced airway inflammation.

Enhancement of growth hormone bioactivity by zinc in the eluted stain assay system

The effects of ionic zinc (Zn2+) on human (h) GH bioactivity have been examined using a lactogenic bioassay. The potencies of pituitary-derived hGH (IRP 80/505), recombinant 22K hGH (IRP 88/624), pituitary-derived human PRL (IRP 84/500), and a recombinant methionyl 20-kilodalton variant of hGH in the presence of selected concentrations of ZnCl2 were investigated with an eluted stain assay that uses Nb2 rat lymphoma cells. This precise colorimetric bioassay is based upon the reduction of a yellow tetrazolium salt, 3-[4,5-dimethyl-thiazol-2-yl]2,5-di-phenyl-tetrazolium bromide, to its purple formazan by lactogen-activated Nb2 cells. Zinc (6-100 microM) enhanced the bioactivity of low doses (< 0.045 nM) of both pituitary-derived and recombinant 22K hGH, although the magnitude of enhancement was considerably less than might have been anticipated from previous binding studies (13). Higher concentrations of pituitary-derived hGH (> 0.045 nM) were inhibited by Zn2+. The bioactivity of recombinant methionyl 20K hGH was greatly enhanced by zinc (3-100 microM). In contrast to hGH, the bioactivity of hPRL was not potentiated by Zn2+. These discriminatory effects of Zn2+ when stimulating via the lactogenic receptor are in concordance with the results of previous radioligand binding studies (13). The striking enhancement of 20K hGH lactogenic bioactivity was observed at Zn2+ concentrations within the physiological range for normal human serum (5-20 microM).

Cognitive and motor skills in achondroplastic infants: neurologic and respiratory correlates

Thirteen infants with achondroplasia underwent psychometric testing as part of a comprehensive neurologic assessment. As a group, mental development was average and motor development was delayed, although a wide range of scores was obtained. Foramen magnum measurements were correlated with respiratory dysfunction, abnormal somatosensory evoked potentials, and delayed motor development. Abnormal polysomnogram outcome was associated with reduced mental capacity. In light of the reported increased frequency of respiratory dysfunction in achondroplasia, these findings warrant careful attention and further study.

The Type A experience: occupational and life demands, satisfaction and well-being

This study investigated the relationship of Type A behavior to occupational and life demands, occupational and life satisfactions, and emotional and physical health. Respondents were 127 senior administrators of correctional institutions. Data were collected via questionnaires and objective physiological and physical health assessments. Greater Type A's reported more occupational demands, more concrete stressful life events at work, greater interference of work with home and family life, and less marital satisfaction. But greater Type A's also reported more self-esteem at work, greater job involvement and organizational identification and greater life satisfaction. The latter findings highlight the resistance to behavior change by Type A men. Contrary to other studies, Type A behavior bore little relationship to emotional or physical health. Exploratory analyses relating Type A behavior to emotional and physical health did confirm previous findings when the older half of the sample (45 and above) was examined.

Personality, value and behavioral correlates of the type A individual

127 senior administrators of correctional institutions completed a self-report Type A scale as well as measures of personality, work values, social participation, and coping behaviors. Greater Type As were more rigid, had stronger needs for social approval, and were more social. Their work values were more in line with the Protestant work ethic. Greater Type As were also more active in community organizations, but not in friendships, and preferred active coping behaviors. Implications for Type A behavior change programs are offered.

Sex differences in adolescent life stress, social support, and well-being

The present study compared male and female adolescents in terms of experienced life stress, social support recieved from parents and peers, and emotional and physical well-being. Ss were 93 male and 181 female adolescents obtained from three high schools. Data were collected by anonymous questionnaires. The results showed that female adolescents reported significantly greater life stress, and although they received significantly more social support from peers, they also reported significantly poorer emotional and physical well-being than males. An explanation for these findings in terms of difficulties in the socialization of female adolescents is proposed.

Husband-wife helping-relationships: the "mental hygiene" function in marriage

This study examined the relationships between several correlates and consequences of the husband-wife helping-relationship. 189 husband-wife pairs provided information about several aspects of their: experienced stress, their informal helping-relationship, and their satisfactions and well-being. Effective husband-wife helping-relationships were signficantly related to the quality of life of the marital partners.

Disclosure of problems and tensions experienced by marital partners

189 husband-wife pairs indicated how likely they were to disclose to their spouses when they were experiencing problems, and their reasons for disclosing and/or not disclosing. Wives disclosed significantly more than husbands. Both gave similar reasons for disclosing, but different reasons for not disclosing. Husbands and wives who were more likely to disclose to their spouses also reported greater marital and life satisfaction, but level of disclosing was not related to measures of mental and physical well-being or job satisfaction.

Personality characteristics associated with giving and receiving help

Adult males over females frequently involved in helping others with day-to-day difficulties reported greater needs to express affection and control than males and females infrequently involved in helping others. (Study ns: 228 men, 214 women.) Females frequently involved in helping also had greater need for expressed and wanted inclusion.