Modulation of biliverdin dynamics and spectral properties by Sandercyanin

Biliverdin IX-alpha (BV), a tetrapyrrole, is found ubiquitously in most living organisms. It functions as a metabolite, pigment, and signaling compound. While BV is known to bind to diverse protein families such as heme-metabolizing enzymes and phytochromes, not many BV-bound lipocalins (ubiquitous, small lipid-binding proteins) have been studied. The molecular basis of binding and conformational selectivity of BV in lipocalins remains unexplained. Sandercyanin (SFP)–BV complex is a blue lipocalin protein present in the mucus of the Canadian walleye (Stizostedion vitreum). In this study, we present the structures and binding modes of BV to SFP. Using a combination of designed site-directed mutations, X-ray crystallography, UV/VIS, and resonance Raman spectroscopy, we have identified multiple conformations of BV that are stabilized in the binding pocket of SFP. In complex with the protein, these conformers generate varied spectroscopic signatures both in their absorption and fluorescence spectra. We show that despite no covalent anchor, structural heterogeneity of the chromophore is primarily driven by the D-ring pyrrole of BV. Our work shows how conformational promiscuity of BV is correlated to the rearrangement of amino acids in the protein matrix leading to modulation of spectral properties.

Biliverdin IX-alpha undergoes rotation around the D-ring pyrrole and displays a broad far-red absorbance on binding to monomeric Sandercyanin variant (orange) compared to the wild-type tetrameric protein (cyan).     

Objective assessment of the human visual attentional state

Primary objective

The purpose of this study was to develop an objective way to assess human visual attention using the alpha-band component of the visual-evoked potential (VEP).

Design and methods

Six different attentional conditions were tested: eyes-open, eyes-closed, eyes-closed with backwards number counting, and three rapid-serial visual presentation (RSVP) tasks. Eighteen visually normal, young-adult subjects (ages 21–28 years) were tested binocularly at 1 m for each condition on two separate days. The Diopsys? NOVA-TR system was used to obtain the visual-evoked potential (VEP) and extracted alpha wave and its related power spectrum. Additionally, the Visual Search and Attention Test (VSAT) was administered as a subjective measure of visual attention.

Results

Subjects exhibited significant decreases in power in the alpha band when comparing the eyes-closed with the eyes-open conditions, with power in the eyes-closed condition being, on average, twice as large. The response from the other four conditions did not reflect the differential attentional demands. The ratio of the power in the eyes-closed condition to the eyes-open condition in the lower-alpha frequencies (8–10 Hz) was found to be significantly correlated with the group’s performance on the VSAT, especially the 10-Hz component.

Conclusions

An individual’s ability to attenuate their alpha component during visual processing may be a predictor of their visual attentional state. These findings solidify the role of the VEP alpha subcomponent as an objective electrophysiological correlate of visual attention, which may be useful in the diagnosis and treatment of human visual attention disorders in the future.     

Pseudo-aneurysm of mitral aortic intervalvular fibrosa: Two case reports

The fibrous body between the mitral and aortic valve, known as mitral-aortic intervalvular fibrosa (MAIVF) is prone to infection and injury resulting in pseudo-aneurysm formation. Because of its relative rarity, we are far from making any conclusion regarding the natural history and appropriate therapeutic strategy for this condition. We report two cases of this condition with two different and rare etiologies with strikingly different natural courses, providing insight into the natural course and timing of surgery in this rare entity.     

Local warming at injection site helps alleviate pain after rocuronium administration

Purpose

Various strategies have been proposed to reduce discomfort of pain after rocuronium injection. These studies have shown pretreatment of drugs such as fentanyl and lidocaine to be effective. In a prospective randomized study, we evaluated whether pretreatment with local warming at injection site using an air-warming device could effectively alleviate pain induced by rocuronium.

Methods

Ninety patients undergoing spinal surgeries were randomly divided into two groups: group C (control) and group T (treatment). Patients in group T were subjected to warming at 40°C for 1 min prior to injecting 1 ml (10 mg) of rocuronium at the site of venous access. Patients were then assessed for any discomfort and to quantify their discomfort on a 5-point scale.

Results

Age, sex, and weight were comparable between the two groups. Pain on rocuronium administration was reported by 88.9% patient in group C versus 66.7% in group T (p < 0.05). Severe pain was significantly less in group T (35.6% vs. 8.9%).

Conclusion

Application of warmth over the vascular access prior to rocuronium administration effectively reduces injection-related pain.     

“Extended length” endoscopic harvest of the great saphenous vein for coronary artery bypass grafting

Introduction The endoscopically harvested vein from thigh usually falls short by half to one length in patients requiring multiple conduits. Increased risk of complications precludes routine endoscopic vein harvest from the leg and an extra incision for open technique is often required thereby nullifying the sole purpose of the former. We employed the endoscope to harvest this extra length of vein from the upper half of the leg with little or no extra risk. Methods From January 2006 to September 2006 we endoscopically harvested the vein in thigh as well as the leg using the same entry point incision over the medial epicondyle in 40 cases. The only exclusion criterion for the study was a superficial location and subcutaneous visibility of the vein in the leg. We made 3 incisions in each patient of average size 2.5 cm. Results Five patients required conversion to the open technique. The average harvest time was 59 minutes. Average length of the conduit was 48 cms. Complications included 1 minor wound infection, 1 case of superificial wound dehiscence, 1 haematoma requiring aspiration and minor erythema at the incision site in 2 patients. Most common complication observed was ecchymosis in 6 patients (5 high; 3 leg). None of the patient developed lymphoedema and none required re-hospitalization for vein harvest related wound complications. Conclusion “Extended endoscopic vein harvest” and avoidance of the open incision was possible in most patients with no additional risk and that the procedure could be routinely employed in patients requiring multiple conduits.     

Chimeric superficial temporal artery based skin and temporal fascia flap plus temporalis muscle flap �C An alternative to free flap for suprastructure maxillectomy with external skin defect

Flaps from temporal region have been used for mid face, orbital and peri-orbital reconstruction. The knowledge of the vascular anatomy of the region helps to dissect and harvest the muscle/fascia/skin/combined tissue flaps from that region depending upon the requirement. Suprastructure maxillectomy defects are usually covered with free flaps to fill the cavity. Here we report an innovative idea in which a patient with a supra structure maxillectomy with external skin defect was covered with chimeric flap based on the parietal and frontal branches of superficial temporal artery and the temporalis muscle flap based on deep temporal artery.KEY WORDS: Chimeric flap, orbital floor defect, suprastructure maxillectomy, superficial temporal artery     

“Dynamic” liver retraction at laparoscopy: An easy and effective technique

Liver retraction is an essential step during any laparoscopic upper gastrointestinal operation, especially during dissection at the oesophageal hiatus. However, the generally employed Nathanson retractor may cause significant postoperative liver dysfunction secondary to congestion of the liver.1,2 It may be technically cumbersome to systematize its frequent use intraoperatively and it may not be readily available at large. Furthermore, the unabated pressure it inflicts on the left lobe of the liver, especially during prolonged surgeries, may lead to hepatic ischaemic necrosis, gangrene, or even unexpected mortality.1 While few recently developed innovative liver retraction techniques seem useful in this context, 2-5 they tend to offer a “static” liver retraction. In this paper, we describe an easy-to-use method of laparoscopic liver retraction wherein any 5mm laparoscopic instrument can be used to manipulate the “heavy” liver so as to provide a “dynamic” counter-traction at will.