Vibrational sum frequency study on biological interfaces

Vibrational sum frequency spectroscopy (VSFS) is a nonlinear optical process. The sum frequency signal is proportional to the square of second order nonlinear susceptibility, which is proportional to the average of polarizabilities of molecules, which is related to molecular orientation. Since the polarizabilities of molecules in bulk phase will be canceled out, a sum frequency signal can only be generated from interfaces where the inversion symmetry is broken. Because of its interfacial specificity, VSFS has been applied to study many interfacial phenomena. In this dissertation we investigated various biological interfaces with VSFS. Fibrinogen adsorption was studied at the protein/solid interface in combination with atomic force microscopy (AFM), immunoassay, and VSFS. Astonishing changes in the interfacial water orientation accompanied by the pH changes provided fibrinogen’s adsorption mechanism up to the amino acid level. Enzymatic fragmentation of fibrinogen revealed that the adsorption property of fibrinogen was mainly from the alpha C fragments of the protein. Mimicking of the fibrinogen binding site with polypeptides was successfully performed and showed very similar properties of fibrinogen adsorption. Protein stability is sensitive to the salts in solutions. The ability of ions to stabilize protein was ordered by Hofmeister in 1888 and the order is SO4 2- ≅ HPO4 2- > F- > Cl- > Br- > NO3 - > I- (≅ ClO4 -) > SCN-. Even though the phenomenon was observed in various biological systems, the origin of those ionic effects is still not well understood. We studied ion effects on alkyl chain ordering and interfacial water structure for octadecylamine, dimethyldidodecylammonium bromide, and dilauroylphosphotidyl choline monolayers. Because of its ability to probe a hydrophobic moiety and interfacial water at the same time, VSFS provided further information to understand the Hofmeister series. We found that the Hofmeister effect is a combinatorial effect of screening effects, ion binding, and dispersion forces

Orthodontic bonding procedures significantly influence biofilm composition

Background Because changes in surface properties affect bacterial adhesion, orthodontic bonding procedures may significantly influence biofilm formation and composition around orthodontic appliances. However, most studies used a mono-species biofilm model under static conditions, which does not simulate the intraoral environment and complex interactions of oral microflora because the oral cavity is a diverse and changeable environment. In this study, a multi-species biofilm model was used under dynamic culture conditions to assess the effects of the orthodontic bonding procedure on biofilm formation and compositional changes in two main oral pathogens, Streptococcus mutans and Porphyromonas gingivalis. Methods Four specimens were prepared with bovine incisors and bonding adhesive: untreated enamel surface (BI), enamel surface etched with 37% phosphoric acid (ET), primed enamel surface after etching (PR), and adhesive surface (AD). Surface roughness (SR), surface wettability (SW), and surface texture were evaluated. A multi-species biofilm was developed on each surface and adhesion amounts of Streptococcus mutans, Porphyromonas gingivalis, and total bacteria were analyzed at day 1 and day 4 using real-time polymerase chain reaction. After determining the differences in biofilm formation, SR, and SW between the four surfaces, relationships between bacteria levels and surface properties were analyzed. Results The order of SR was AD < PR < BI < ET, as BI and ET showed more irregular surface texture than PR and AD. For SW, ET had the greatest value followed by PR, BI, and AD. S. mutans and P. gingivalis showed greater adhesion to BI and ET with rougher and more wettable surfaces than to AD with smoother and less wettable surfaces. The adhesion of total bacteria and S. mutans significantly increased over time, but the amount of P. gingivalis decreased. The adhesion amounts of all bacteria were positively correlated with SR and SW, irrespective of incubation time. Conclusions Within the limitations of this study, changes in SR and SW associated with orthodontic bonding had significant effects on biofilm formation and composition of S. mutans and P. gingivalis.This work was supported by the National Research Foundation of Korea [NRF-2017R1A2B4001834]

The Effect of Clonidine Pretreatment on Epidural Resiniferatoxin in a Neuropathic Pain Rat Model

Resiniferatoxin (RTX) is an ultrapotent synthetic TRPV1 (transient receptor potential vanilloid subtype 1) agonist with significant initial transient hyperalgesia followed by a prolonged analgesic effect in response to thermal stimulus. Using a rat model of neuropathic pain, we evaluated the effect of pretreatment with clonidine－which has been shown to relieve intradermal capsaicin-induced hyperalgesia－on the initial hyperalgesic response and the thermal analgesic property of RTX. Thirty-six male rats were divided into 6 treatment groups (n＝6 each):RTX 500ng, RTX 1μg, clonidine 20μg (Cl), Cl＋RTX 500ng, Cl＋RTX 1μg, or normal saline 20μL (control). We evaluated the short-term (180min) and long-term (20 days) analgesic effects of RTX after thermal stimulation and mechanical stimulation. RTX had significant initial transient hyperalgesia followed by a prolonged analgesic effect in response to the thermal stimulus, but the RTX 500ng and RTX 1μg groups showed no initial short-term thermal hyperalgesic responses when pretreated with clonidine. The Cl＋RTX 1μg ratsʼ behavior scores indicated that they were more calm and comfortable compared to the RTX 1μg rats. Even though we cannot precisely confirm that pretreatment with clonidine potentiates or adds to the analgesic effect of RTX, clonidine pretreatment with epidural RTX eliminated the initial RTX-associated hyperalgesic response and systemic toxicity in this neuropathic pain rat model

Autosomal dominant transmission of complicated hereditary spastic paraplegia due to a dominant negative mutation of KIF1A, SPG30 gene.

KIF1A is a brain-specific anterograde motor protein that transports cargoes towards the plus-ends of microtubules. Many variants of the KIF1A gene have been associated with neurodegenerative diseases and developmental delay. Homozygous mutations of KIF1A have been identified in a recessive subtype of hereditary spastic paraplegia (HSP), SPG30. In addition, KIF1A mutations have been found in pure HSP with autosomal dominant inheritance. Here we report the first case of familial complicated HSP with a KIF1A mutation transmitted in autosomal dominant inheritance. A heterozygous p.T258M mutation in KIF1A was found in a Korean family through targeted exome sequencing. They displayed phenotypes of mild intellectual disability with language delay, epilepsy, optic nerve atrophy, thinning of corpus callosum, periventricular white matter lesion, and microcephaly. A structural modeling revealed that the p.T258M mutation disrupted the binding of KIF1A motor domain to microtubules and its movement along microtubules. Assays of peripheral accumulation and proximal distribution of KIF1A motor indicated that the KIF1A motor domain with p.T258M mutation has reduced motor activity and exerts a dominant negative effect on wild-type KIF1A. These results suggest that the p.T258M mutation suppresses KIF1A motor activity and induces complicated HSP accompanying intellectual disability transmitted in autosomal dominant inheritance. © The Author(s) 20171

Delayed Rupture of the Right Sinus of Valsalva into the Right Atrium after Percutaneous Coronary Intervention

Rupture of the sinus of Valsalva is an extremely rare complication after percutaneous coronary intervention (PCI). Because it usually results from the retrograde extension of a dissection of the right coronary artery and may quickly spread to involve the entire aorta, it can cause life-threatening complications such as aortic dissection. If the dissection remains localized, it can resolve spontaneously in the first month. Our patient experienced a delayed rupture of the right sinus of Valsalva into the right atrium at approximately 3 months after PCI

Effects of 92% oxygen administration on cognitive performance and physiological changes of intellectually and developmentally disabled people

Background: The present study addressed how 92% oxygen administration affects cognitive performance, blood oxygen saturation (SpO(2)), and heart rate (HR) of intellectually and developmentally disabled people. Methods: Seven males (28.9 +/- 1.8 years) and seven females (34.4 +/- 8.3 years) with intellectual and developmental disabilities (disabled level 2.1 +/- 0.5) completed an experiment consisting a 0-back task with normal air (21% oxygen) administered in one run and hyperoxic air (92% oxygen) administered in the other run. The experimental sequence in each run consisted of a 1-min adaptation phase, 2-min control phase, and 2-min 0-back task phase, where SpO(2) and HR were gauged for each phase. Results: The administration of 92% oxygen increased 0-back task performance of intellectually and developmentally disabled people, in association with increased SpO(2) and decreased HR. Our results demonstrate that sufficient oxygen supply subserving cognitive functions, even as a short-term effect, could increase cognitive ability for the intellectually and developmentally disabled people. Conclusions: It is concluded that enriched oxygen can positively affect, at least in the short-term, the working memory of those with intellectual and developmental disabilityopen0