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.

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.

Diagnostic accuracy of oropharyngeal cultures in infants and young children with cystic fibrosis

The objective of this study was to assess the diagnostic accuracy of oropharyngeal (OP) cultures relative to simultaneous bronchoalveolar lavage (BAL) cultures in very young children with CF, and to examine the effects of bacterial density, age, and study cohort on diagnostic accuracy. Respiratory culture data were analyzed from three independent, prospective studies involving simultaneous collection of 286 OP and BAL cultures from 141 children with CF <5 years of age. For predicting any growth of Pseudomonas aeruginosa (Pa) from the lower airway in subjects </=18 months of age (mean age, 8 +/- 5 months), OP cultures had a sensitivity of 44% (95% CI 14%, 79%), specificity of 95% (90%, 99%), positive predictive value of 44% (14%, 79%), and negative predictive value of 95% (90%, 99%). Diagnostic accuracy was similar for Haemophilus influenzae (Hi). Specificity was significantly lower for Staphylococcus aureus (Sa). Sensitivity for all organisms improved if a positive lower airway culture was defined as >/=10(3) or >/=10(5) cfu/mL. Specificity for Pa declined significantly with increasing age. In children with CF <5 years of age, the specificity and negative predictive value of OP cultures for Pa are high, while the sensitivity and positive predictive value are poor. Thus, in this age range, a negative throat culture is helpful in "ruling out" lower airway infection with Pa. However, a positive culture does not reliably "rule in" the presence of Pa in the lower respiratory tract. These findings may have implications for study design and interpretation as well as clinical management of young children with CF.

3D printed microfluidic devices with integrated versatile and reusable electrodes

We report two 3D printed devices that can be used for electrochemical detection. In both cases, the electrode is housed in commercially available, polymer-based fittings so that the various electrode materials (platinum, platinum black, carbon, gold, silver) can be easily added to a threaded receiving port printed on the device; this enables a module-like approach to the experimental design, where the electrodes are removable and can be easily repolished for reuse after exposure to biological samples. The first printed device represents a microfluidic platform with a 500 × 500 μm channel and a threaded receiving port to allow integration of either polyetheretherketone (PEEK) nut-encased glassy carbon or platinum black (Pt-black) electrodes for dopamine and nitric oxide (NO) detection, respectively. The embedded 1 mm glassy carbon electrode had a limit of detection (LOD) of 500 nM for dopamine and a linear response (R(2) = 0.99) for concentrations between 25-500 μM. When the glassy carbon electrode was coated with 0.05% Nafion, significant exclusion of nitrite was observed when compared to signal obtained from equimolar injections of dopamine. When using flow injection analysis with a Pt/Pt-black electrode and standards derived from NO gas, a linear correlation (R(2) = 0.99) over a wide range of concentrations (7.6-190 μM) was obtained, with the LOD for NO being 1 μM. The second application showcases a 3D printed fluidic device that allows collection of the biologically relevant analyte adenosine triphosphate (ATP) while simultaneously measuring the release stimulus (reduced oxygen concentration). The hypoxic sample (4.8 ± 0.5 ppm oxygen) released 2.4 ± 0.4 times more ATP than the normoxic sample (8.4 ± 0.6 ppm oxygen). Importantly, the results reported here verify the reproducible and transferable nature of using 3D printing as a fabrication technique, as devices and electrodes were moved between labs multiple times during completion of the study.

Dissociating the dual roles of apoptosis-inducing factor in maintaining mitochondrial structure and apoptosis

The mitochondrial protein apoptosis-inducing factor (AIF) translocates to the nucleus and induces apoptosis. Recent studies, however, have indicated the importance of AIF for survival in mitochondria. In the absence of a means to dissociate these two functions, the precise roles of AIF remain unclear. Here, we dissociate these dual roles using mitochondrially anchored AIF that cannot be released during apoptosis. Forebrain-specific AIF null (tel. AifDelta) mice have defective cortical development and reduced neuronal survival due to defects in mitochondrial respiration. Mitochondria in AIF deficient neurons are fragmented with aberrant cristae, indicating a novel role of AIF in controlling mitochondrial structure. While tel. AifDelta Apaf1(-/-) neurons remain sensitive to DNA damage, mitochondrially anchored AIF expression in these cells significantly enhanced survival. AIF mutants that cannot translocate into nucleus failed to induce cell death. These results indicate that the proapoptotic role of AIF can be uncoupled from its physiological function. Cell death induced by AIF is through its proapoptotic activity once it is translocated to the nucleus, not due to the loss of AIF from the mitochondria.

Relationships among milk production, energy balance, plasma analytes, and reproduction in Holstein-Friesian cows

Associations were examined between components and indicators of early lactation energy balance (EB) and measures of fertility in Holstein cows. Milk production, dry matter intake (DMI), body condition score (BCS), and endocrine and metabolite data from 96 cows were analyzed using multivariate logistic regression and survival analysis. Fertility variables investigated were interval to commencement of luteal activity (C-LA), calving to conception interval (CCI), and conception rate to first service (CON1). Mean daily EB, milk protein content, and DMI during the first 28 d in milk were associated positively with CON1. Cows having poorer BCS (< or =2.25) at first service had a lower CON1. Positive associations were identified among EB, milk protein content, DMI, and the likelihood of a shorter interval to C-LA. Cows having greater DMI and a more positive EB had an increased likelihood of a shorter CCI, whereas a lower nadir BCS was associated with an increased likelihood of a longer CCI. Milk yield was not associated with any of the fertility variables investigated. A greater plasma concentration of insulin-like growth factor I (IGF-I) during the first 2 wk of lactation was associated with a greater CON1 and an increased likelihood of a shorter interval to C-LA. In conclusion, we identified DMI as the principal component of EB influencing subsequent fertility. Furthermore, results indicate that milk protein content and plasma IGF-I concentration in early lactation may be useful indicators of reproductive efficiency.

HLA class I (A, B) and II (DR, DQ) gene and haplotype frequencies in blood donors from Wales

Accurate estimates of HLA-A, B, DR and DQ phenotype, gene and haplotype frequencies (HF) in the normal population are of importance in, for example, disease susceptibility studies, platelet transfusion support and transplantation. HLA population genetics studies have been performed on numerous groups, however, no major studies have been carried out on the population of Wales. As part of the validation process for our routine HLA-A and B typing by PCR using sequence-specific primers (PCR-SSP) we examined 1,798 normal, unrelated Caucasoid blood donors living in Wales and recruited onto the Welsh Bone Marrow Donor Registry (WBMDR). Typing was performed by serology (HLA-A, B) and PCR-SSP at low resolution (HLA-A, B, DR, DQ) resulting in a particularly rigorous level of HLA specificity assignment. Four discrepancies were found between the HLA-A and B serological and PCR-SSP specificity assignments: (1) two instances of HLA-A2 by serology were undetected by PCR-SSP and were a new HLA-A2 allele - A*0224; (2) one example of HLA-B*15 by PCR-SSP failed to react by serology, and remained undetectable by serology in subsequent samples, and (3) one example of HLA-B45 by serology was identified as HLA-B*5002 by PCR-SSP. Hardy-Weinberg and homozygosity analysis showed that the goodness-of-fit was excellent (p > 0.05), for both phenotype distribution and the number of homozygotes identified, for all four loci. The phenotype and gene frequencies for the 18 HLA-A, 34 -B, 15 -DR and 8 -DQ specificities identified and two- and three-locus HF, linkage disequilibrium and related values for HLA-A/B, B/DR, DR/DQ and HLA-A/B/DR and B/DR/DQ were essentially typical of a northern European population. HLA-A2, B44, DR4 and DQ2 were the highest frequency phenotypes and HLA-A2403, A34, A74, B42, B75, B2708, B48, B67 and B703 occurred once only. There were no examples of: A36, A43, A69, A80, B46, B54, B59, B73, B76, B77, B7801, B8101 or DR18 specificities. DR17, DQ2 and A1, B8, DR17 were the highest frequency two- and three-locus haplotypes identified. Diverse HLA-A, B, DR phenotypes were identified in 87.0% (1,564) of subjects. When HLA-DQ was also considered, different four locus phenotypes were identified in 89.1% (1,602) of subjects. This frequency information will be beneficial as a high-quality reference control for disease susceptibility studies and in calculating the chances of identifying a bone marrow donor in a patient's extended family. This process was successful for the validation of our HLA-A and -B PCR-SSP typing procedure and the findings suggest an accurate level of specificity assignment of WBMDR panel donors who had previously been typed by serology alone.

Effects of different transition diets on dry matter intake, milk production, and milk composition in dairy cows

The primary objective of this study was to evaluate the effect on dry matter intake (DMI), milk yield, milk composition, body weight (BW), and body condition score (BCS) change of cows offered diets differing in energy density in the last 4 wk of gestation and in the first 8 wk of lactation. Three diets (grass silage:straw, 75:25 on a dry matter basis (SS), grass silage (S), and grass silage + 3 kg concentrate daily (C)) precalving, and two diets (4 kg [LC] or 8 kg [HC] concentrate daily + grass silage ad libitum) postcalving were combined in a 3 x 2 factorial design. Sixty Holstein-Friesian cows entering their second lactation were blocked according to expected calving date and BCS into groups of six and were then allocated at random to the treatments. Individual feeding started 4 wk prior to the expected calving date and measurements were made until the end of the 8th wk of lactation. Mean DMI differed between each of the precalving treatments (7.4, 8.1, and 9.9 kg/d for SS, S, and C, respectively) in the precalving period. The DMI also differed between SS and C for wk 1 to 8 (13.5 and 14.2 kg/d) postcalving. Postcalving, milk (24.2, 26.2, and 28.2 kg/d), fat (933, 1063, and 1171 g/d), and protein (736, 797, and 874 g/d) yields differed between SS, S, and C, respectively. The BCS changes differed between SS and C (-0.09 and 0.12 of a BCS) in the precalving period and between SS and S compared with C (0.02, 0.06, and -0.26 of a BCS) for wk 1 to 8 postcalving. The BW change differed between SS and S compared with C in both wk 1 to 4 (-0.23, -0.37, and -1.25 kg/d) and wk 1 to 8 (0.18, 0.10, and -0.58 kg/ d) postcalving. The BW and BCS were lower at calving for cows on SS compared with C. The greater amount of concentrate supplement postcalving increased DMI, yields of milk, fat, and protein and decreased BW loss in the first 8 wk of lactation. In conclusion, these results indicate that a greater energy density diet in the final 4 wk of the dry period improves cow production in early lactation.

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.

Disposition of drugs in cystic fibrosis. I. Sulfamethoxazole and trimethoprim

The disposition of sulfamethoxazole and trimethoprim, after constant rate intravenous administration (10 mg/kg/hr sulfamethoxazole and 2 mg/kg/hr trimethoprim for 1 hour), was investigated in adult patients with cystic fibrosis (n = 7) and in age-matched healthy subjects (control subjects, n = 8). The total plasma clearance of sulfamethoxazole was found to be increased in cystic fibrosis (0.0262 +/- 0.0064 L/hr/kg) when compared with that found in control subjects (0.0188 +/- 0.0043 L/hr/kg). This increase in clearance was found to be primarily attributable to an increase in the metabolic clearance of sulfamethoxazole to N4-acetylsulfamethoxazole (0.00903 +/- 0.00247 versus 0.00355 +/- 0.00049 L/hr/kg) with the renal clearance of sulfamethoxazole remaining unchanged. These conclusions were not altered when the pharmacokinetic parameters were computed for the unbound drug or when they were normalized with respect to body surface area. These data indicate that, in cystic fibrosis, the enzymes mediating the metabolism of sulfamethoxazole to N4-acetylsulfamethoxazole, N-acetyltransferase(s), may be induced, activated, or both, or that the uptake of sulfamethoxazole by cells that metabolize sulfamethoxazole to N4-acetylsulfamethoxazole is enhanced. The total plasma clearance of trimethoprim was also found to be increased in cystic fibrosis (0.1808 +/- 0.0440 L/hr/kg) when compared with that found in control subjects (0.1139 +/- 0.0193 L/hr/kg). In contrast to sulfamethoxazole, this increase in clearance was found to be primarily attributable to an increase in the renal clearance of trimethoprim (0.1240 +/- 0.0299 versus 0.0720 +/- 0.0166 L/hr/kg). These data indicate that the tubular secretion of trimethoprim may be enhanced in cystic fibrosis.

Survey of nurses' assessment of cancer-related fatigue

Fatigue is now widely recognised as a significant' problem for patients with cancer. While research effort into this subject has grown considerably in recent years, the exact mechanisms underlying fatigue remain unclear. Therefore assessing and managing this symptom can be problematic. This paper describes the findings from a survey evaluating how nurses (n = 84) in a Cancer Centre in Edinburgh currently define and assess fatigue. The results demonstrate that while the problems associated with fatigue are acknowledged, assessment tools are not widely used and the majority of nurses report that they would benefit from further education on the subject to assist in the care of patients.

Effect of offering rumen-protected fat supplements on fertility and performance in spring-calving Holstein-Friesian cows

The objective of this study was to evaluate the effect of two different rumen-protected fat supplements, on reproductive performance and milk production, in grass-based spring calving cows. Two hundred and one Holstein-Friesian cows with an average lactation number of 3.6 (20% first lactation, 16% second lactation and 64% third lactation or greater) were grouped into blocks of three on the basis of calving date, lactation number and previous lactation milk yield for cows of second lactation or greater and on the basis of calving date for first lactation animals. From within-blocks individual animals were assigned at random, within 10 days post-calving, to one of the following three treatments: (1) Megalac Plus 3% (MP; 0.4kg/day, containing Ca salt of palm fatty acids and Ca salt of methionine hydroxy analogue), (2) Megapro Gold (MPG; 1.5kg/day, containing Ca salt of palm fatty acids, extracted rapeseed meal and whey permeate), and (3) Control (C; unsupplemented). Cows were supplemented for on average 103 days (range 54-134 days). The average milk yield over the first 12 weeks of lactation was higher (P<0.05) for both fat supplements compared to C and was higher for MP compared to C over the full lactation. Both supplements reduced (P<0.05) milk protein concentration over the first 6 weeks of lactation. MPG increased (P<0.05) conception rate to first service compared to C. Conception rate to first service was similar (P=0.14) on MP compared to C. For pregnancy to second service, C had a higher (P<0.05) conception rate than MP. There were no significant differences between treatments in overall pregnancy rate, services per conception, number of cows served in the first 3 weeks of the breeding season or the 6-weeks in-calf rate. Comparing the combined fat treatments to C resulted in a higher (P<0.05) conception rate to first service for the fat treatments but no significant difference in overall pregnancy rate. In conclusion, fat supplements increased conception rate to first service but did not significantly affect the proportion of cows pregnant at the end of the breeding season.

Fluorescence polarization assay for the diagnosis of bovine brucellosis: adaptation to field use

A fluorescence polarization assay (FPA) was used to test whole blood samples prepared by mixing blood cells from cattle without exposure to Brucella abortus (B. abortus) with sera from animals with confirmed (bacteriologically) infection. A cut-off value between negative and positive values was initially established to be 87.2mP. This value was changed to 95mP to increase assay specificity without loss of sensitivity when testing blood samples from negative animals. The FPA technology was applied to whole blood samples in the field and to stored whole blood samples using two diluent buffers. Relative sensitivity and specificity values for the FPA performed in the field, based on buffered antigen plate agglutination test and competitive enzyme immunoassay results were 95.3 and 97.3%, respectively. However, to obtain maximum sensitivity and specificity, a cut-off value of 105mP was determined for fresh whole blood samples. The relative sensitivity and specificity values of the FPA when testing stored whole blood samples were 100% each using a 95mP cut-off.The usefulness of the FPA for testing whole blood samples in the field was demonstrated.

Resting-state connectivity deficits associated with impaired inhibitory control in non-treatment-seeking adolescents with psychotic symptoms

OBJECTIVE

Psychotic symptoms are common in the population and index risk for a range of severe psychopathological outcomes. We wished to investigate functional connectivity in a community sample of adolescents who reported psychotic symptoms (the extended psychosis phenotype).

METHOD

This study investigated intrinsic functional connectivity (iFC) during resting-state functional magnetic resonance imaging (fMRI; rs-fMRI). Following screening in schools, 11 non-treatment seeking, youth with psychotic symptoms (aged 11-13) and 14 community controls participated in the study. Seed regions of interest comprised brain regions previously shown to exhibit aberrant activation during inhibitory control in adolescents with psychotic symptoms.

RESULTS

Relative to controls, adolescents with psychotic symptoms exhibited reduced iFC between regions supporting inhibitory control. Specifically, they showed weaker iFC between the right inferior frontal gyrus (IFG) and the cingulate, IFG and the striatum, anterior cingulate and claustrum, and precuneus and supramarginal gyrus. Conversely, the psychotic symptoms group exhibited stronger iFC between the superior frontal gyrus and claustrum and IFG and lingual gyrus.

CONCLUSION

The present findings are the first to reveal aberrant functional connectivity in resting-state networks in a community sample of adolescents with psychotic symptoms and suggest that disruption in integration between distributed neural networks (particularly between prefrontal, cingulate and striatal brain regions) may be a key neurobiological feature of the extended psychosis phenotype.

Respiratory challenge induces high frequency spiking on the static charge sensitive bed (SCSB)

The static charge sensitive bed (SCSB) is a simple and noninvasive device used for the detection of sleep apnoea. In addition to episodes of apnoea or hypopnoea, heavy snorers commonly present with episodes of high frequency spiking on the SCSB. These spiking episodes have been claimed to represent partial upper airway obstruction during sleep, but the mechanism of their appearance is not known. We studied the SCSB spiking phenomenon in awake subjects during experimental respiratory challenge. One female and five male volunteers were studied whilst breathing freely, during hypoxia, hypercapnia and inspiratory and expiratory loading. Oxygen saturation, end-tidal carbon dioxide tension, minute ventilation, oesophageal pressure, electrocardiographic activity (ECG), blood pressure and the SCSB signals were monitored. During free breathing, the SCSB high frequency signal consisted of low amplitude complexes with close time relationship to the cardiac cycle. During respiratory challenge, spiking occurred. These spikes showed no time relationship to the cardiac cycle, but were time-linked to the onset of inspiration or expiration. Spike amplitude correlated with breathing frequency (r2 = 0.59; p < 0.005) and variation in oesophageal pressure (r2 = 0.57; p < 0.005). We conclude that during quiet, unobstructed breathing the static charge sensitive bed high frequency signal represents cardiac activity (ballistocardiogram), whereas during high-drive breathing high frequency spikes are produced. These spikes are respiratory in origin and are likely to represent fast components of respiratory movements. Our results support the use of static charge sensitive bed spiking as a noninvasive measure of breathing stimulation.

Changes in fecal microbiota with CFTR modulator therapy: A pilot study

Studies have demonstrated that people with CF with pancreatic insufficiency (PI) have fecal dysbioses. Evidence suggests the causes of these dysbioses are multifactorial, and that important drivers include antibiotic exposure, dietary intake, and CF gastrointestinal tract dysfunction, including nutrient malabsorption. In this pilot study, we tested whether initiation of the CFTR modulator treatments ivacaftor (in a cohort of pancreatic sufficient (PS) people with CF and an R117H CFTR variant) or lumacaftor/ivacaftor (in a cohort of PI people with CF and an F508del variant) changed fecal measures of malabsorption or fecal microbiomes. While we identified no statistically significant fecal changes with either treatment, we detected trends in the PI cohort when initiating lumacaftor/ivacaftor towards decreased fecal fat content and towards fecal microbiomes that more closely resembled the fecal microbiota of people without PI. While these findings support a model in which nutrient malabsorption resulting from CF-induced PI drives fecal dysbiosis, they must be validated in future, larger studies of fecal microbiome and malabsorption outcomes with highly effective CFTR modulator therapies.

Disposition of drugs in cystic fibrosis. V. In vivo CYP2C9 activity as probed by (S)-warfarin is not enhanced in cystic fibrosis

Enhanced metabolism of theophylline in subjects with cystic fibrosis suggests that the activity of certain cytochrome P450 isoforms is affected in subjects with this genetic disease. To determine whether this effect on the P450 enzymes is selective, the in vivo activity of the cytochrome P450 isoform CYP2C9 was determined in adult subjects with cystic fibrosis (n = 6) and in control subjects (n = 8). Subjects were administered (S)-warfarin as a single intravenous bolus dose (0.375 mg/kg), and urine and plasma samples were collected for 96 hours. Plasma (S)-warfarin concentrations were determined by HPLC; urinary concentrations of (S)-warfarin and its metabolites were determined by gas chromatography-mass spectrometry. The total plasma clearance of (S)-warfarin (subjects with cystic fibrosis, 3.6 +/- 0.48 ml/hr/kg; control subjects, 3.82 +/- 0.73 ml/hr/kg), elimination half-life (subjects with cystic fibrosis, 29.5 +/- 4.2 hours; control subjects, 25.9 +/- 5.4 hours); and steady-state volume of distribution (subjects with cystic fibrosis, 153 +/- 18 ml/kg; control subjects, 138 +/- 22 ml/kg) were similar in the two groups (p > 0.05). The metabolic clearance of (S)-warfarin to its major metabolites mediated by CYP2C9, 6-hydroxywarfarin and 7-hydroxywarfarin, was not significantly (p > 0.05) different between the two groups (6-hydroxywarfarin: subjects with cystic fibrosis, 0.33 +/- 0.1 ml/hr/kg; control subjects, 0.41 +/- 0.1 ml/hr/kg; 7-hydroxywarfarin: subjects with cystic fibrosis, 1.34 +/- 0.49 ml/hr/kg; control subjects, 1.8 +/- 0.45 ml/hr/kg). On the basis of these data, we conclude that the in vivo cytochrome P450 activity is selectively affected in persons with cystic fibrosis.

Origin of the hydrodynamic Lyapunov modes

Recent studies of the Lyapunov spectrum of the hard sphere fluid reveal that there are "hydrodynamic" Lyapunov exponents corresponding to collective perturbations in phase space. We show that these collective perturbations are due to the conservation of certain quantities during collisions. These new conservation laws generate new hydrodynamic fields, just as the conservation of mass, momentum, and energy generate the density, velocity, and temperature fields. We then construct a detailed theory of the new hydrodynamic fields using a kinetic theory approach. This theory predicts several properties of the modes, but not all of them. This suggests that the underlying idea is correct, but a detailed theory must be elaborated in another way. The hydrodynamic exponents are not related in a simple way to the transport coefficients.