Discrimination between respiratory and non-respiratory sound waveforms in dogs using acoustic wave recordings: An objective metric of cough.

Cough is an important respiratory protective mechanism, which when persistent also contributes to disease pathology. It is therefore both a marker for and a target of therapeutic intervention. In dogs, assessment of cough is subjective, generally based on owner's perceptions of clinical signs. In humans, acoustic cough monitoring provides objective data on cough frequency by examining acoustic waveforms. We hypothesized that healthy mesocephalic dogs would demonstrate characteristic cough waveforms which could be distinguished from other acoustic behaviors (AB); whine, bark, growl, lick, drink, chew and throat-clear. Data were obtained from 10 healthy employee-owned dogs. Acoustic behaviors were recorded using a CTA-laryngeal-microphone and analyzed using RavenPro bioacoustics software for nine objective acoustic parameters (AP). Similarity between AB were assessed using a one-way analysis of similarity (ANOSIM) with a P<0.001 significance level. Inter- and intra-group statistical analysis was performed using a one-way ANOVA on ranks with P<0.05 significance level. With the exception of throat-clear, cough was dissimilar to every other evaluated AB (P<0.0001), with significant differences in one or more of the analyzed waveform parameters (P<0.001 for each). No between-subject differences were identified between cough and throat-clear groups for any parameter. All other behaviors showed statistically significant within-group variation (P<0.001). Cough and throat-clear (a clinically similar mechanism to protect the airways) have repeatable acoustic features that are distinguishable from other common AB and are consistent between dogs. Acoustic monitoring may provide an objective means for evaluating cough frequency and intensity in dogs with respiratory disease and assessing response to therapeutic intervention.

Mechanical dilation, botulinum toxin A injection, and surgical myotomy with fundoplication for treatment of lower esophageal sphincter achalasia-like syndrome in dogs.

BACKGROUND: Megaesophagus (ME) carries a poor long-term prognosis in dogs. In people, lower esophageal sphincter (LES) achalasia is a rare cause of ME that may respond to targeted intervention. Dogs with lower esophageal sphincter achalasia-like syndrome (LES-AS) have been described recently, warranting investigation of analogous targeted treatment. HYPOTHESIS/OBJECTIVES: Evaluate response of dogs with LES-AS to LES mechanical dilation and botulinum toxin A (BTA) injections, with or without surgical myotomy and fundoplication. We hypothesized that clinical and videofluoroscopic swallow study (VFSS) features of LES-AS would improve after treatment targeting functional LES obstruction. ANIMALS: Fourteen client-owned dogs with LES-AS diagnosed by VFSS. METHODS: Retrospective study. Dogs diagnosed with LES-AS underwent treatment between April 2015 and December 2017. Outcome measures included client perception of clinical severity, body weight (BW), body condition score (BCS), regurgitation frequency, and VFSS parameters (ME, esophageal motility, gastric filling). Dogs with positive responses were considered candidates for LES myotomy with fundoplication. RESULTS: By a median IQR of 21 (IQR, 14-25) days after mechanical dilation and BTA, clients reported clinical improvement in 100% of dogs, BW increased 20.4% (IQR, 12.7%-25%), pre- and post-treatment BCS was 3 (IQR, 3-4) and 5 (IQR, 4-5), respectively, and frequency of regurgitation decreased by 80% (IQR, 50%-85%). Duration of effect was 40 (IQR, 17-53) days. Despite clinical improvement, ME and abnormal esophageal motility persisted in 14 dogs. Six dogs subsequently underwent myotomy and fundoplication and maintained improvement observed after mechanical dilation and BTA. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with LES-AS experienced significant, temporary, clinical improvement after mechanical dilation and BTA. Preliminary results suggest myotomy with fundoplication provide lasting clinical benefit despite persistence of ME.

Standardization of a Videofluoroscopic Swallow Study Protocol to Investigate Dysphagia in Dogs.

BACKGROUND: Videofluoroscopic swallow study (VFSS) is the gold standard for diagnosis of dysphagia in veterinary medicine but lacks standardized protocols that emulate physiologic feeding practices. Age impacts swallow function in humans but has not been evaluated by VFSS in dogs. HYPOTHESIS/OBJECTIVES: To develop a protocol with custom kennels designed to allow free-feeding of 3 optimized formulations of contrast media and diets that address limitations of current VFSS protocols. We hypothesized that dogs evaluated by a free-feeding VFSS protocol would show differences in objective swallow metrics based on age. ANIMALS: Healthy juvenile, adult, and geriatric dogs (n = 24). METHODS: Prospective, experimental study. Custom kennels were developed to maintain natural feeding behaviors during VFSS. Three food consistencies (thin liquid, pureed food, and dry kibble) were formulated with either iohexol or barium to maximize palatability and voluntary prehension. Dogs were evaluated by 16 swallow metrics and compared across age groups. RESULTS: Development of a standardized VFSS protocol resulted in successful collection of swallow data in healthy dogs. No significant differences in swallow metrics were observed among age groups. Substantial variability was observed in healthy dogs when evaluated under these physiologic conditions. Features typically attributed to pathologic states, such as gastric reflux, were seen in healthy dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Development of a VFSS protocol that reflects natural feeding practices may allow emulation of physiology resulting in clinical signs of dysphagia. Age did not result in significant changes in swallow metrics, but additional studies are needed, particularly in light of substantial normal variation.

Effects of effortful swallow on esophageal function in healthy adults.

BACKGROUND: Treatment for esophageal dysmotility is currently limited to primarily pharmacologic intervention, which has questionable utility and frequently associated negative side effects. A potential behavioral intervention for esophageal dysmotility is the effortful oropharyngeal swallow. A previous pilot study using water perfusion manometry found an increase in distal esophageal amplitudes during effortful vs non-effortful swallowing. The current study sought to duplicate the previous study with improvements in methodology. METHODS: The effects of swallow condition (effortful vs non-effortful), sensor site, and gender on esophageal amplitude, duration, velocity, and bolus clearance were examined for 18 adults (nine males and nine females, mean age = 29.9 years) via combined solid-state manometry and intraluminal impedance. KEY RESULTS: The effortful swallow condition yielded significantly higher esophageal amplitudes across all sensor locations (P < 0.05). Further, the effortful swallowing decreased the risk of incomplete bolus clearance when compared with non-effortful swallowing (OR: 0.51; 95% CI: 0.30-0.86). CONCLUSIONS & INFERENCES: With improved manometric instrumentation, larger participant numbers, and methodology that controlled for potential confounding factors, this study confirms and advances the results of the previous pilot study: Volitional manipulation of the oropharyngeal phase of swallowing using the effortful swallow indeed affects esophageal physiology. Thus, the effortful swallow offers a behavioral manipulation of the esophageal phase of swallowing, and future studies will determine its clinical potential for treating esophageal dysmotility in patient populations.

Long-term cardiac outcome in high-risk patients undergoing elective endovascular or open infrarenal abdominal aortic aneurysm repair.

OBJECTIVES: To assess long-term outcome of patients at high cardiac risk undergoing endovascular or open AAA repair. METHODS: Patients undergoing open or endovascular infrarenal AAA repair with >or=3 cardiac risk factors and preoperative cardiac stress testing (DSE) at 2 university hospitals were studied. Main outcome was cardiac event free and overall survival. Multivariate Cox regression analysis was used to evaluate the influence of type of AAA repair on long-term outcome. RESULTS: In 124 patients (55 endovascular, 69 open) the number and type of cardiac risk factors, medication use and DSE results were similar in both groups. In multivariable analysis, adjusting for cardiac risk factors, stress test results, medication use, and propensity score endovascular repair was associated with improved cardiac event free survival (HR 0.54; 95% CI 0.30-0.98) but not with an overall survival benefit (HR 0.73; 95% CI 0.37-1.46). Importantly, statin therapy was associated with both improved overall survival (HR 0.42; 95% CI 0.21-0.83) and cardiac event free survival (HR 0.45; 95% CI 0.23-0.86). CONCLUSIONS: The perioperative cardiac benefit of endovascular AAA repair in high cardiac risk patients is sustained during long-term follow-up provided patients are on optimal medical therapy but it is not associated with improved overall long-term survival.

An investigation into the use of micro-thermal analysis for the solid state characterisation of an HPMC tablet formulation.

The use of micro-thermal analysis (microTA) as a novel means of differentiating between components in a model tablet formulation is described. This technique involves a modification of atomic force microscopy (AFM) such that the standard AFM tip is replaced with a Wollaston wire, thereby allowing the probe to act as a thermistor and temperature probe. Consequently it is possible to map not only the topology but also the thermal conductivity of the sample. Furthermore, it is possible to apply a heating signal to the material and thereby to perform thermal analysis on highly localised regions of the sample. Compacts were prepared comprising ibuprofen, HPMC E4M prem and 1:1 mixes of the two components and analysed using a microTA micro-thermal analyser. The surface topology and conductivity images of the three systems are reported. In addition, the ability of the technique to perform thermal analysis on highly specific regions of the sample is described. The method was able to differentiate between the components of the sample on the basis of micro-thermomechanical experiments. The implications of the use of the technique for the study of pharmaceutical tablets is discussed.

Purification and properties of the H(+)-nicotinamide nucleotide transhydrogenase from Rhodobacter capsulatus.

1. H(+)-transhydrogenase from Rhodobacter capsulatus is an integral membrane protein which, unlike the enzyme from Rhodospirillum rubrum, does not require the presence of a water-soluble component for activity. 2. The enzyme from Rb. capsulatus was solubilised in Triton X-100 and subjected to ion-exchange, hydroxyapatite and then gel-exclusion column chromatography. SDS/PAGE of the purified enzyme revealed the presence of two polypeptides with apparent Mr 53,000 and 48,000. Other minor components which were stained on the electrophoresis gels or which were revealed on Western blots exposed to antibodies raised to total membrane proteins, were probably contaminants. 3. Antibodies raised to the 53-kDa and 48-kDa polypeptides cross-reacted with equivalent polypeptides in Western blots of solubilised membranes from Rb. capsulatus, Rhodobacter sphaeroides and Rhs. rubrum. The significance of this finding is discussed in the context of the hypothesis [Fisher, R.R. & Earle, S.R. (1982) The pyridine nucleotide coenzymes, pp. 279-324, Academic Press, New York] that the soluble component associated with H(+)-transhydrogenase from Rhs. rubrum is an integral part of the catalytic machinery. Antibodies against the 48-kDa and 53-kDa polypeptides of the Rb. capsulatus enzyme cross-reacted with equivalent polypeptides in solubilised membranes of Escherichia coli. 4. The dependence of the rate of H- transfer by purified H(+)-transhydrogenase on the nucleotide substrate concentrations under steady-state conditions, the effects of inhibition by nucleotide products and the inhibition by 2'-AMP and by 5'-AMP suggest that the reaction proceeds by the random addition of substrates to the enzyme with the formation of a ternary complex. 5. In conflict with this conclusion, the reduction of acetylpyridine adenine dinucleotide (AcPdAD+) by NADH in the absence of NADP+ by bacterial membranes was earlier taken as evidence for the existence of a reduced enzyme intermediate [Fisher, R.R. & Earle, S.R. (1982) The pyridine nucleotide coenzymes, pp. 279-324, Academic Press, New York]. However, it is shown here that although chromatophore membranes of Rb. capsulatus catalysed the reduction of AcPdAD+ by NADH, the reaction was not associated with the purified H(+)-transhydrogenase. Moreover, in contrast with the true transhydrogenase reaction, the reconstitution of AcPdAD+ reduction by NADH (in the absence of NADP+) in washed membranes of Rhs. rubrum with partially purified transhydrogenase factor, was only additive.

The coupling between protonmotive force and the NAD(P)+ transhydrogenase in chromatophores from photosynthetic bacteria.

1. The activity of NAD(P)+ transhydrogenase in chromatophores of Rhodobacter capsulatus relaxed from a high rate during illumination to a lower rate after darkening with a half-time of approximately 100 ms. 2. The dissipative ionic current flowing across the chromatophore membrane was increased in the presence of transhydrogenase substrates. This is attributed to proton current through the transhydrogenase enzyme. Subject to the assumption that transhydrogenase does not conduct in the absence of nucleotide substrates, the ratio of protons translocated across the membrane per hydride ion transferred was 0.4 +/- 0.5. Within the error and uncertainities in the calibration procedure, this ratio may be consistent with a stoichiometry of one but higher values seem unlikely. The ratio of hydride ion transferred in the transhydrogenase to electrons transferred through the cyclic electron transport system was approximately 0.2. 3. The Kappm values for the transhydrogenase substrates were determined for chromatophores in illuminated and darkened suspensions over a range of pH. These values are discussed in relation to the equivalent parameters reported for mitochondria transhydrogenase [Rydstrom, J. (1977) Biochim. Biophys. Acta 255, 9641-9646] and were used to calculate the concentrations of substrates which effectively saturate the enzyme. 4. At substrate concentrations which were in excess of 8 X Kappm the dependence of transhydrogenase rate on the value of the membrane potential (zero pH gradient) was determined at pH 6.3, 6.9, 7.6 and 9.0. The relation was similar at pH 6.9 and 7.6. At alkaline pH the apparent threshold in the relation became more prominent as it was shifted to slightly higher values of membrane potential. At acid pH a shift in the opposite direction diminished the apparent threshold and saturation at high membrane potential became more dominant. We use these data in an attempt to discriminate between two models of energy transduction: (a) the driving force exerted by the membrane potential is mediated by a pH gradient formed through the operation of a proton well in the transhydrogenase; (b) the membrane potential increases a rate constant for charge translocation through transhydrogenase by decreasing the effective height of the Eyring barrier for charge transfer across the membrane through the enzyme. The second model leads to a more simple description than the first of the pH dependence of transhydrogenase rate on membrane potential.4+ transhydrogenase activity in chromatopho