Mucous solids and liquid secretion by airways: studies with normal pig, cystic fibrosis human, and non-cystic fibrosis human bronchi

To better understand how airways produce thick airway mucus, nonvolatile solids were measured in liquid secreted by bronchi from normal pig, cystic fibrosis (CF) human, and non-CF human lungs. Bronchi were exposed to various secretagogues and anion secretion inhibitors to induce a range of liquid volume secretion rates. In all three groups, the relationship of solids concentration (percent nonvolatile solids) to liquid volume secretion rate was curvilinear, with higher solids concentration associated with lower rates of liquid volume secretion. In contrast, the secretion rates of solids mass and water mass as functions of liquid volume secretion rates exhibited positive linear correlations. The y-intercepts of the solids mass-liquid volume secretion relationships for all three groups were positive, thus accounting for the higher solids concentrations in airway liquid at low rates of secretion. Predictive models derived from the solids mass and water mass linear equations fit the experimental percent solids data for the three groups. The ratio of solids mass secretion to liquid volume secretion was 5.2 and 2.4 times higher for CF bronchi than for pig and non-CF bronchi, respectively. These results indicate that normal pig, non-CF human, and CF human bronchi produce a high-percent-solids mucus (>8%) at low rates of liquid volume secretion (≤1.0 μl·cm(-2)·h(-1)). However, CF bronchi produce mucus with twice the percent solids (~8%) of pig or non-CF human bronchi at liquid volume secretion rates ≥4.0 μl·cm(-2)·h(-1).     

Assessment of the Correlation Between Two Defining Criteria for Bidirectional Isthmic Block in the Ablation of Typical Atrial Flutter

Background

A complete, bidirectional conduction block in the cavotricuspid isthmus (CTI) represents the end-point of the typical atrial flutter ablation. We investigated the correlation between two criteria for successful ablation, one based on the atrial bipolar electrogram morphology before and after complete CTI conduction block, compared to the standard criteria of differential pacing and reversal in the right atrial depolarization sequence during coronary sinus (CS) pacing.

Method

We conducted a retrospective study in 111 patients (81 males, average age 62±10 years) who underwent an atrial flutter ablation during September 2007 - July 2009 in the Cardiology - Rehabilitation Hospital, UMF Cluj-Napoca. We assessed the presence of a bidirectional block at the end of the procedure using the standard criteria. We then analyzed the morphology of the bipolar atrial electrograms adjacent to the ablation line, before and after CTI conduction block.

Results

A change from a qRs morphology to a rSr'' morphology when pacing from the coronary sinus and from a rsr'' morphology to a QRS morphology when pacing from the low-lateral right atrium was associated with a CTI conduction block. Sensitivity (Se), specificity(Sp), positive predictive value (PPV), negative predictive value (NPV) were 96%, 89%, 99% and 67% respectively.

Conclusion

Our study suggests that the analysis of the atrial bipolar electrogram next to the ablation line before and after CTI ablation may be used as a reliable criterion to validate CTI conduction block due to its high sensitivity, specificity and positive predictive value.     

Prolonged Survival of Campylobacter Species in Bovine Manure Compost

The persistence of naturally occurring campylobacteria in aerobic compost constructed of manure from beef cattle that were administered chlortetracycline and sulfamethazine (AS700) or from cattle not administered antibiotics (control) was examined. Although there were no differences in population sizes of heterotrophic bacteria, the temperature of AS700 compost was more variable and did not become as high as that of control compost. There were significant differences in water content, total carbon (C), total nitrogen (N), and electrical conductivity but not in the C/N ratio or pH between the two compost treatments. Campylobacteria were readily isolated from pen manure, for up to day 15 from control compost, and throughout the active phase of AS700 compost. Campylobacter DNA (including Campylobacter coli, Campylobacter fetus, Campylobacter hyointestinalis, and Campylobacter jejuni) was detected over the ca. 10-month composting period, and no reductions in quantities of C. jejuni DNA were observed over the duration of the active phase. The utilization of centrifugation in combination with ethidium monoazide (EMA) significantly reduced (>90%) the amplification of C. jejuni DNA that did not originate from cells with intact cell membranes. No differences were observed in the frequency of Campylobacter DNA detection between EMA- and non-EMA-treated samples, suggesting that Campylobacter DNA amplified from compost was extracted from cells with intact cell membranes (i.e., from viable cells). The findings of this study indicate that campylobacteria excreted in cattle feces persist for long periods in compost and call into question the common belief that these bacteria do not persist in manure.Campylobacter jejuni and, to a lesser extent, Campylobacter coli incite serious acute and chronic afflictions. Enteritis caused by C. jejuni (i.e., campylobacteriosis) is the most common cause of bacterial enteritis in Canada (http://dsol-smed.phac-aspc.gc.ca/dsol-smed/ndis/index-eng.php). Although the epidemiology of campylobacteriosis is poorly understood, sporadic outbreaks of campylobacteriosis involving contaminated water have occurred when water treatment has failed. The most serious outbreak in Canada occurred in Walkerton Ontario in 2000; more than 2,300 people became infected with waterborne Escherichia coli O157:H7 and/or C. jejuni originating from cattle feces (3). Alberta, Canada, possesses a very large beef cattle population (≈6 million animals) primarily concentrated in the southern region of the province, and ≈2 million of these animals are in finishing feedlots (1). Large quantities of manure are produced by feedlot cattle. For example, in the Chinook Health Region of Southwestern Alberta in which Lethbridge is situated, there are ≈700,000 cattle in feedlots at any given time, producing ≈12 million kg of manure (fresh weight) per day. Several Campylobacter species, including C. jejuni and C. coli, are frequently shed in beef cattle feces in large numbers (15, 16). Although the impact of cattle-borne campylobacters on human health has not been definitely determined, the southern region of Alberta possesses one of the highest rates of campylobacteriosis in Canada among its human inhabitants, concomitant with the very high density of cattle in this region.Large-scale windrow composting of bovine manure from intensive cattle operations is practiced by some Alberta feedlots. Composting is an aerobic process in which organic matter in manure is stabilized into a humus-like product (30). The process results in water loss and mass reduction, nutrient transformation (22), alteration of physical structure (23), elimination of weed seeds (21), and the inactivation of coliform bacteria (25), protozoan cysts and oocysts (34), and viruses (39). Limited research has investigated the impact of manure management systems, such as aerobic composting, on deactivation of campylobacters. Furthermore, the impact of antimicrobial agents excreted into the manure on the efficacy of the composting process on Campylobacter deactivation has not been investigated. Most studies conducted to date have indicated that campylobacters do not persist well in solid manure once excreted (7, 11, 12, 26, 32, 39). Although it is difficult to isolate or enumerate Campylobacter species within microbiologically complex substrates, molecular detection and/or quantification methods have not been extensively applied to study the persistence of campylobacteria. Furthermore, the persistence of naturally shed campylobacteria has largely been overlooked. Thus, the overall objective of the current study was to measure the ability of campylobacteria naturally shed in bovine feces to persist in manure compost using a combination of culture- and culture-independent methods. Specific objectives were (i) to develop and utilize a centrifugation method to facilitate isolation and detection of DNA from Campylobacter species in bovine manure compost, (ii) to apply qualitative and quantitative PCR methods to evaluate persistence of campylobacteria in compost, (iii) to validate the molecular methods used to amplify DNA from viable cells, and (iv) to contrast the persistence of Campylobacter species in composted manure obtained from beef cattle maintained on a diet supplemented with chlortetracycline and sulfamethazine (AS700) with composted manure from animals not administered antimicrobial agents.     

Formation of proline thiohydantoin with ammonium thiocyanate: progress towards a viable C-terminal amino-acid-sequencing procedure.

Pure amino acid thiohydantoins are required as reference standards for development of C-terminal-sequencing procedures based on thiohydantoin formation of the C-terminal amino acids of peptides and proteins. Proline thiohydantoin was prepared using a straightforward method involving reaction of acetylproline with ammonium thiocyanate. It was characterized by UV spectrophotometry, mass spectrometry and back-hydrolysis to the free amino acid. These data establish unequivocally that the thiocyanate procedure is applicable to proline as well as to the other common amino acids. This work also validates earlier claims that proline thiohydantoin can be prepared by reaction with thiocyanic acid.     

Boat harbour design can exacerbate hull fouling

Abstract Hull fouling is a major cost for owners of small vessels and an important pathway for the spread of non‐indigenous aquatic species. The extent of fouling depends on a hull's susceptibility to recruitment by aquatic organisms and the local availability of competent planktonic propagules (‘propagule pressure’). Management strategies have typically been concerned with increasing resistance of the hull to recruitment through the use of toxic paints. Here we tested the hypothesis that fouling is influenced by the design of the harbour in which the boat is moored. We compared recruitment of sessile invertebrates to available surfaces in two types of recreational boat harbours: marinas that were partially enclosed by a permanent breakwall, and marinas that lacked breakwalls. Recruitment in the marinas was compared to coastal reference sites that were not used for mooring. At each location, recruitment tiles were deployed for 4 weeks on four separate occasions over a period of 2 years. Measurements of current velocities and spatial patterns of water flow at each location showed that permanent breakwalls created complex patterns of circulation that retained water within the marina basin for up to 12 h d^?1. Despite large regional and temporal variability in fouling over time, most organisms recruited in greatest numbers to surfaces in partially enclosed marinas, and were often several orders of magnitude more abundant in the enclosed marinas than in unenclosed marinas or coastal reference locations. Harbour design has an important influence on the rate at which fouling organisms recruit to available surfaces within marinas. Entrainment of water in enclosed marinas may limit the dispersal of planktonic propagules by advective currents but effectively increases propagule pressure to available surfaces, including resident boat hulls. This is likely to accelerate the development of hull‐fouling assemblages and increase the chances of transport of non‐indigenous species that establish populations in the harbour basin.     

Electromyographic recordings of paraspinal muscles: Variations related to subcutaneous tissue thickness

The aim of this study was to assess the effect on EMG amplitude measures of variations in the thickness of underlying tissue between surface electrodes and the active muscle. 20 normal subjects with different amounts of subcutaneous tissue performed comparable constant force contractions for a 45-second period, during which paraspinal EMG recordings were taken. Three measures of subcutaneous tissue thickness were obtained from each subject: Body Mass Index, total body fat as calculated by Durnin's formula, and skinfold thickness at the recording sites. The results show that (i) the greater the thickness of subcutaneous tissue between the surface recording site and the contracting muscles, the lower the recorded electromyographic activity, and that (ii) up to 81.2% of the variance in the EMG measures can be explained by variation in the amount of subcutaneous tissue. These findings support the view that the absolute level of surface-recorded EMG cannot simply be taken at face value. The amplitude of the signal will be affected by, for example, the amount of body fat.Supported by the Physician's Services Inc. Foundation.