Bezold-Jarisch Reflex Induced by Dopamine during Isoflurane Anesthesia in Small Dogs

Background: Unlike other major reflexes contributing to hemodynamic homeostasis, the Bezold-Jarisch reflex (BJR) paradoxically decreases heart rate (HR) and mean arterial pressure (MAP) despite hypotension. In the veterinary field, there are few reported cases of BJR induced by dopamine, which is often used to manage hypotension. Herein, 2 cases involving small dogs exhibiting BJR due to dopamine infusion during general anesthesia are described.Cases: Case 1: A 7-year-old, 7 kg, mongrel was referred for external skeletal fixator removal. The patient was premedicated with 0.3 mg/kg midazolam and 0.2 mg/kg butorphanol intravenously (IV). General anesthesia was induced with 6 mg/kg propofol and maintained with 1.6% isoflurane in oxygen. The patient was given 5 mL/kg/h of Hartmann’s solution IV. The respiratory rate (RR) was set to 9 breaths/min with a ventilator. The HR and MAP values were initially 120 bpm and 76 mmHg and gradually decreased to 70 bpm and 40 mmHg, respectively. The end-tidal CO2 partial pressure (ETCO2) was 39 mmHg, and the patient was administered 2.5 μg/kg glycopyrrolate IV. Then, 5 μg/kg/min dopamine was administered IV since the MAP did not improve. The HR, MAP, and ETCO2 increased to 113 bpm, 72 mmHg, and 47 mmHg, respectively. Subsequently, HR and MAP dramatically decreased to 50 bpm and 43 mmHg, respectively. A second-degree atrioventricular block was detected, prompting dopamine infusion discontinuation, and 2.5 μg/kg glycopyrrolate was again administered IV. Within 5 min, HR and MAP values normalized, and postoperative patient recovery was typical. Case 2: A 2-year-old, 8.6 kg, mongrel underwent surgery to correct a medial luxating patella of the right leg. The patient was premedicated with 0.3 mg/kg midazolam and 0.2 mg/kg butorphanol IV. Anesthesia was induced with 4 mg/kg propofol IV and maintained with 3% isoflurane in oxygen; 10 mL/kg/h of Hartmann’s solution was administered IV. Within 15 min, the patient’s HR and MAP values decreased from 120 to 107 bpm and 73 to 50 mmHg, respectively. The ETCO2remained approximately 39 mmHg, and RR decreased from 20 to 17 breaths/min. Dopamine was infused at a rate of 5 µg/kg/min. After 10 min, the MAP slightly increased from 50 to 57 mmHg, but the HR dramatically decreased from 107 to 62 bpm and the RR also dropped to 12 breaths/min. Further, a second-degree atrioventricular block was observed. Dopamine infusion was immediately discontinued, and 2.5 μg/kg glycopyrrolate was injected IV. As the HR returned to 94 bpm, the atrioventricular block disappeared, and the RR increased to 15 breaths/min. After general anesthesia was terminated, the patient recovered well.Discussion: Among drugs used for anesthesia, propofol and isoflurane may lower the MAP and HR. Therefore, HR or MAP decreases at the beginning of anesthesia are likely due to the drugs. Considering half-life, it is unlikely that propofol provoked sudden HR or MAP decreases at about 25 min post-induction. Isoflurane may also be ruled out since the hemodynamic disorder depended on dopamine injection. Sudden decreases in the HR, MAP, or RR after dopamine injection are not generally expected dopaminergic or adrenergic responses, which likely occur due to the vagal cardiopulmonary reflex suggesting the BJR resulting from activation of cardiac mechano- or chemoreceptors. To the best of our knowledge, there have been no reports of dopamine-mediated BJR in young or middle-aged, small dogs. The BJR has been observed in older, larger dogs and humans. In the patients described, body condition score may be considered when estimating the cause of the BJR. Since they scored 8/9, it is possible that obesity increased the risk of the BJR. This report described the clinical features and treatment outcomes in young or middle-aged, obese, small-sized dogs, whose hypotension or bradycardia was exacerbated by dopamine.Keywords: Bezold-Jarisch reflex, dopamine, hypotension, bradycardia, canine.

Lyotropic columnar liquid crystals based on polycatenar 1H-imidazole amphiphiles and their assembly into bundles at the surface of silicon

Polycatenar 1H-imidazole amphiphiles, consisting of a 1H-imidazole head connected through a benzene ring to a trialkyloxyphenyl tail, were synthesized and their self-assembling properties investigated. The 1 H NMR and fluorescence spectroscopy studies showed that in nonpolar solvents, the amphiphiles formed reverse micelles in which the hydrophilic imidazole heads aggregated inside the micelles through intermolecular hydrogen bonding and the nonpolar alkyl chains were located at the periphery of the micelles. In concentrated solutions, they formed lyotropic liquid crystals having columnar hexagonal structures. The molecules were arranged in a disk via hydrogen bonding between successive imidazole moieties. When dilute solutions of the amphiphiles in n-hexane (0.1 wt%) were spin-coated on to a plasma-cleaned Si wafer, a band-like structure with a width of 60-100 nm was imaged by AFM. Microscopic fiber bundles with a diameter as large as 13 mm were observed by SEM when the lyotropic liquid crystals in 30 wt% hexane solution were dried on the glass

Optical spectroscopic investigation on the coupling of electronic and magnetic structure in multiferroic hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films

We investigated the effects of temperature and magnetic field on the electronic structure of hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films using optical spectroscopy. As the magnetic ordering of the system was disturbed, a systematic change in the electronic structure was commonly identified in this series. The optical absorption peak near 1.7 eV showed an unexpectedly large shift of more than 150 meV from 300 K to 15 K, accompanied by an anomaly of the shift at the Neel temperature. The magnetic field dependent measurement clearly revealed a sizable shift of the corresponding peak when a high magnetic field was applied. Our findings indicated strong coupling between the magnetic ordering and the electronic structure in the multiferroic hexagonal RMnO3 compounds.Comment: 16 pages including 4 figure

Long-Term Glycaemic Durability of Early Combination Therapy Strategy versus Metformin Monotherapy in Korean Patients with Newly Diagnosed Type 2 Diabetes Mellitus

We assessed the glycaemic durability with early combination (EC; vildagliptin+metformin [MET], n=22) versus MET monotherapy (n=17), among newly-diagnosed type 2 diabetes mellitus (T2DM) enrolled (between 2012 and 2014) in the VERIFY study from Korea (n=39). Primary endpoint was time to initial treatment failure (TF) (glycosylated hemoglobin [HbA1c]>= 7.0% at two consecutive scheduled visits after randomization [end of period 1]). Time to second TF was assessed when both groups were receiving and failing on the combination (end of period 2). With EC the risk of initial TF significantly reduced by 78% compared to MET (n=3 [15%] vs. n=10 [58.7%], P=0.0228). No secondary TF occurred in EC group versus five patients (29.4%) in MET. Patients receiving EC treatment achieved consistently lower HbA1c levels. Both treatment approaches were well tolerated with no hypoglycaemic events. In Korean patients with newly diagnosed T2DM, EC treatment significantly and consistently improved the long-term glycaemic durability as compared with MET.Peer reviewe

Electronic structures of hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films

We investigated the electronic structure of multiferroic hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films using both optical spectroscopy and first-principles calculations. Using artificially stabilized hexagonal RMnO3, we extended the optical spectroscopic studies on the hexagonal multiferroic manganite system. We observed two optical transitions located near 1.7 eV and 2.3 eV, in addition to the predominant absorption above 5 eV. With the help of first-principles calculations, we attribute the low-lying optical absorption peaks to inter-site transitions from the oxygen states hybridized strongly with different Mn orbital symmetries to the Mn 3d3z2-r2 state. As the ionic radius of the rare earth ion increased, the lowest peak showed a systematic increase in its peak position. We explained this systematic change in terms of a flattening of the MnO5 triangular bipyramid

Solubility enhancement of aggregation-prone heterologous proteins by fusion expression using stress-responsive Escherichia coli protein, RpoS

<p>Abstract</p> <p>Background</p> <p>The most efficient method for enhancing solubility of recombinant proteins appears to use the fusion expression partners. Although commercial fusion partners including maltose binding protein and glutathione-<it>S</it>-transferase have shown good performance in enhancing the solubility, they cannot be used for the proprietory production of commercially value-added proteins and likely cannot serve as universal helpers to solve all protein solubility and folding issues. Thus, novel fusion partners will continue to be developed through systematic investigations including proteome mining presented in this study.</p> <p>Results</p> <p>We analyzed the <it>Escherichia coli </it>proteome response to the exogenous stress of guanidine hydrochloride using 2-dimensional gel electrophoresis and found that RpoS (RNA polymerase sigma factor) was significantly stress responsive. While under the stress condition the total number of soluble proteins decreased by about 7 %, but a 6-fold increase in the level of RpoS was observed, indicating that RpoS is a stress-induced protein. As an N-terminus fusion expression partner, RpoS increased significantly the solubility of many aggregation-prone heterologous proteins in <it>E. coli </it>cytoplasm, indicating that RpoS is a very effective solubility enhancer for the synthesis of many recombinant proteins. RpoS was also well suited for the production of a biologically active fusion mutant of <it>Pseudomonas putida </it>cutinase.</p> <p>Conclusion</p> <p>RpoS is highly effective as a strong solubility enhancer for aggregation-prone heterologous proteins when it is used as a fusion expression partner in an <it>E. coli </it>expression system. The results of these findings may, therefore, be useful in the production of other biologically active industrial enzymes, as successfully demonstrated by cutinase.</p

Subarachnoid Hemorrhage Misdiagnosed as an Acute ST Elevation Myocardial Infarction

Without significant coronary artery stenosis, ischemic electrocardiographic change including ST segment elevation, segmental wall motion abnormality and elevated serum cardiac-specific markers (creatine kinase-MB, Troponin-T) may develop after central nervous system injuries such as subarachnoid, intracranial or subdural hemorrhage. Misdiagnosing these patients as acute myocardial infarction may result in catastrophic outcomes. By reporting a case of a 55-year old female with subarachnoid hemorrhage mimicking acute ST elevation myocardial infarction, we hope to underline that careful attention of neurologic abnormality is critical in making better prognosis

Independent effect of body mass index variation on amyloid-β positivity

ObjectivesThe relationship of body mass index (BMI) changes and variability with amyloid-β (Aβ) deposition remained unclear, although there were growing evidence that BMI is associated with the risk of developing cognitive impairment or AD dementia. To determine whether BMI changes and BMI variability affected Aβ positivity, we investigated the association of BMI changes and BMI variability with Aβ positivity, as assessed by PET in a non-demented population.MethodsWe retrospectively recruited 1,035 non-demented participants ≥50 years of age who underwent Aβ PET and had at least three BMI measurements in the memory clinic at Samsung Medical Center. To investigate the association between BMI change and variability with Aβ deposition, we performed multivariable logistic regression. Further distinctive underlying features of BMI subgroups were examined by employing a cluster analysis model.ResultsDecreased (odds ratio [OR] = 1.68, 95% confidence interval [CI] 1.16–2.42) or increased BMI (OR = 1.60, 95% CI 1.11–2.32) was associated with a greater risk of Aβ positivity after controlling for age, sex, APOE e4 genotype, years of education, hypertension, diabetes, baseline BMI, and BMI variability. A greater BMI variability (OR = 1.73, 95% CI 1.07–2.80) was associated with a greater risk of Aβ positivity after controlling for age, sex, APOE e4 genotype, years of education, hypertension, diabetes, baseline BMI, and BMI change. We also identified BMI subgroups showing a greater risk of Aβ positivity.ConclusionOur findings suggest that participants with BMI change, especially those with greater BMI variability, are more vulnerable to Aβ deposition regardless of baseline BMI. Furthermore, our results may contribute to the design of strategies to prevent Aβ deposition with respect to weight control

Ecological connectivity analysis based on the fish community in Jeongan Stream

This study focused on the longitudinal connectivity analysis, based on fish communities in the aspect of spatial variations of 34 sites from upstream to downstream. The Fish Assessment Index (FAI), based on ecological guilds and species composition, was applied to compare the ecological health among the sampling sites. The total number of 35 fish species, were sampled during the study period with dominant species of Zacco platypus (35.4%) and Zacco koreanus (11.8%). Cluster analysis showed that all sites were categorized as 4 distinct group communities (A, B, C, D). Non-metric multidimensional scaling analysis showed distinct difference between upstream (A, B) and downstream groups (C, D). Indicator Value Analysis (IndVal method), conducted to identify indicator species within each group, indicated that the species favoring upstream environments Rhynchocypris oxycephalus for the Group A and Iksookimia koreensis for the Group B. In contrast, the analysis indicated that the species with a preference for downstream habitats Pseudogobio esocinus for the Group C and Carassius auratus for the Group D. Ecological health, based on the FAI scores, showed a declining pattern toward the downstream, along with an increasing proportion of tolerant species and omnivores within the fish community. Overall these findings suggest the compositions of fish communities, as four groups, were modified by the weir structures and organic matter, nutrient pollutions