Dynamic light filtering over dermal opsin as a sensory feedback system in fish color change.

Dynamic color change has evolved multiple times, with a physiological basis that has been repeatedly linked to dermal photoreception via the study of excised skin preparations. Despite the widespread prevalence of dermal photoreception, both its physiology and its function in regulating color change remain poorly understood. By examining the morphology, physiology, and optics of dermal photoreception in hogfish (Lachnolaimus maximus), we describe a cellular mechanism in which chromatophore pigment activity (i.e., dispersion and aggregation) alters the transmitted light striking SWS1 receptors in the skin. When dispersed, chromatophore pigment selectively absorbs the short-wavelength light required to activate the skin's SWS1 opsin, which we localized to a morphologically specialized population of putative dermal photoreceptors. As SWS1 is nested beneath chromatophores and thus subject to light changes from pigment activity, one possible function of dermal photoreception in hogfish is to monitor chromatophores to detect information about color change performance. This framework of sensory feedback provides insight into the significance of dermal photoreception among color-changing animals.

Effect of a magnetic pulse on orientation behavior in rainbow trout (Oncorhynchus mykiss).

Magnetoreception remains one of the most enigmatic of animal senses. Rainbow trout (Oncorhynchus mykiss) represent an ideal species to study this sense, as magnetoreception based upon microscopic particles of magnetite is suspected to play an important role in their orientation and navigation. Here we found that compared with controls, a magnetic pulse (a treatment commonly used to demonstrate magnetite-based magnetoreception) can induce orientation behavior in juvenile rainbow trout on a specific experimental day. Multiple circular-linear regression also indicated that this effect could at least be partially explained by daily variation in solar electromagnetic activity (i.e., sunspot count and disturbance storm time index). These results are consistent with magnetite-based magnetoreception in rainbow trout and suggest that 1) solar activity may impact magnetic orientation and 2) researchers should be cognizant of its potential consequences on studies of magnetoreception.

Near absence of differential gene expression in the retina of rainbow trout after exposure to a magnetic pulse: implications for magnetoreception.

The ability to perceive the Earth's magnetic field, or magnetoreception, exists in numerous animals. Although the mechanism underlying magnetoreception has not been clearly established in any species, in salmonid fish, it is hypothesized to occur by means of crystals of magnetite associated with nervous tissue such as the brain, olfactory organ or retina. In this study, rainbow trout (Oncorhynchus mykiss) were exposed to a brief magnetic pulse known to disrupt magnetic orientation behaviour in several animals. Changes in gene expression induced by the pulse were then examined in the retina. Analyses indicated that the pulse elicited differential expression of only a single gene, gamma-crystallin M3-like (crygm3). The near absence of an effect of the magnetic pulse on gene expression in the retina stands in sharp contrast to a recent study in which 181 genes were differentially expressed in brain tissue of O. mykiss after exposure to the same pulse. Overall, our results suggest either that magnetite-based magnetoreceptors in trout are not located in the retina, or else that they are unaffected by magnetic pulses that can disrupt magnetic orientation behaviour in animals.

Candidate genes mediating magnetoreception in rainbow trout (Oncorhynchus mykiss).

Diverse animals use Earth's magnetic field in orientation and navigation, but little is known about the molecular mechanisms that underlie magnetoreception. Recent studies have focused on two possibilities: (i) magnetite-based receptors; and (ii) biochemical reactions involving radical pairs. We used RNA sequencing to examine gene expression in the brain of rainbow trout (Oncorhynchus mykiss) after exposure to a magnetic pulse known to disrupt magnetic orientation behaviour. We identified 181 differentially expressed genes, including increased expression of six copies of the frim gene, which encodes a subunit of the universal iron-binding and trafficking protein ferritin. Functions linked to the oxidative effects of free iron (e.g. oxidoreductase activity, transition metal ion binding, mitochondrial oxidative phosphorylation) were also affected. These results are consistent with the hypothesis that a magnetic pulse alters or damages magnetite-based receptors and/or other iron-containing structures, which are subsequently repaired or replaced through processes involving ferritin. Additionally, some genes that function in the development and repair of photoreceptive structures (e.g. crggm3, purp, prl, gcip, crabp1 and pax6) were also differentially expressed, raising the possibility that a magnetic pulse might affect structures and processes unrelated to magnetite-based magnetoreceptors.

Cuttlefish Sepia officinalis Preferentially Respond to Bottom Rather than Side Stimuli When Not Allowed Adjacent to Tank Walls.

Cuttlefish are cephalopods capable of rapid camouflage responses to visual stimuli. However, it is not always clear to what these animals are responding. Previous studies have found cuttlefish to be more responsive to lateral stimuli rather than substrate. However, in previous works, the cuttlefish were allowed to settle next to the lateral stimuli. In this study, we examine whether juvenile cuttlefish (Sepia officinalis) respond more strongly to visual stimuli seen on the sides versus the bottom of an experimental aquarium, specifically when the animals are not allowed to be adjacent to the tank walls. We used the Sub Sea Holodeck, a novel aquarium that employs plasma display screens to create a variety of artificial visual environments without disturbing the animals. Once the cuttlefish were acclimated, we compared the variability of camouflage patterns that were elicited from displaying various stimuli on the bottom versus the sides of the Holodeck. To characterize the camouflage patterns, we classified them in terms of uniform, disruptive, and mottled patterning. The elicited camouflage patterns from different bottom stimuli were more variable than those elicited by different side stimuli, suggesting that S. officinalis responds more strongly to the patterns displayed on the bottom than the sides of the tank. We argue that the cuttlefish pay more attention to the bottom of the Holodeck because it is closer and thus more relevant for camouflage.

Treating pseudomyxoma peritonei without heated intraperitoneal chemotherapy--a first look in New Zealand.

BACKGROUND: Pseudomyxoma peritonei is a condition characterised by dissemination of mucin-producing neoplastic cells throughout the peritoneal cavity. There are two pathological subsets, disseminated peritoneal adenomucinosis and peritoneal mucinosis carcinomatosis. Once a lethal disease, cytoreductive surgery combined with heated intraperitoneal chemotherapy (HIPEC) is challenging debulking as the standard of care. OBJECTIVE: We present the first case series detailing the postoperative morbidity, mortality and survival outcomes of patients treated for pseudomyxoma peritonei by cytoreductive surgery without heated intraperitoneal chemotherapy by a single surgeon. DESIGN: Wellington Hospital clinical databases were retrospectively searched. Inclusion criteria were a diagnosis of pseudomyxoma peritonei with a major cytoreductive operation with the intention of complete cytoreductive clearance. Exclusion criteria were palliative debulking operations and patient records not available for analysis. RESULTS: 25 patients underwent cytoreductive surgery between June 1999 and July 2011. Mean follow-up was 43.5 months (1.5-138). Histological classification was DPAM for 13/25 and PMCA for 12/25. Complete cytoreduction (CC-0 and CC-1) was achieved in 21/25 patients. There was no 30 day mortality following primary cytoreduction. Six patients underwent subsequent debulking/cytoreductive surgery; one patient died following repeat surgery. Clavien-Dindo grade 3 or 4 complications occurred in 7/25 patients. Combined 5-year survival was 64%, 92% for DPAM and 33% for PMCA. CONCLUSION: Cytoreductive surgery alone may result in comparable survival outcomes to those achieved with combined surgery and HIPEC in selected patients, especially for patients with DPAM.

The effect of perioperative psychological intervention on fatigue after laparoscopic cholecystectomy: a randomized controlled trial.

BACKGROUND: Fatigue is one of the main complaints after surgery and may last longer than physical symptoms. It prevents return to normal function and activity. Relaxation interventions, performed prior to abdominal surgery, have been shown to reduce pain, wound erythema, and systemic cortisol levels. However, there is a lack of data on the impact of this intervention on patient well-being, functional recovery, activities of daily living, and fatigue after discharge from hospital. METHODS: The study was a randomised single-blinded trial. Patients who were to undergo elective laparoscopic cholecystectomy for any indication between April 2008 and May 2010 were screened for inclusion. Those in the intervention group attended a standardised 45 min relaxation session with a health psychologist and were given relaxation exercise CDs to take home. The control group did not have the intervention. Patients were followed for 30 days. Fatigue was measured using the identity-consequence fatigue scale. RESULTS: Seventy-five patients were randomised. Fifteen patients were excluded after randomization for various reasons; hence, 60 patients were followed up and analysed. Both groups had similar fatigue at baseline. There was improved fatigue and consequence of fatigue on postoperative day 30 in the intervention group. There was no difference in fatigue at any other time point postoperatively. CONCLUSION: This was the first interventional study targeting fatigue after laparoscopic cholecystectomy by using a brief psychological relaxation intervention. It has shown a reduction of fatigue and impact of fatigue at 30 days postoperatively in the intervention group.

A brief relaxation intervention reduces stress and improves surgical wound healing response: a randomised trial.

Psychological stress has been shown to impair wound healing, but experimental research in surgical patients is lacking. This study investigated whether a brief psychological intervention could reduce stress and improve wound healing in surgical patients. This randomised controlled trial was conducted at a surgical centre. Inclusion criteria were English-speaking patients over 18 years booked to undergo elective laparoscopic cholecystectomy; exclusion criteria were cancellation of surgery, medical complications, and refusal of consent. Seventy five patients were randomised and 15 patients were excluded; 60 patients completed the study (15 male, 45 female). Participants were randomised to receive standard care or standard care plus a 45-min psychological intervention that included relaxation and guided imagery with take-home relaxation CDs for listening to for 3 days before and 7 days after surgery. In both groups ePTFE tubes were inserted during surgery and removed at 7 days after surgery and analysed for hydroxyproline as a measure of collagen deposition and wound healing. Change in perceived stress from before surgery to 7-day follow-up was assessed using questionnaires. Intervention group patients showed a reduction in perceived stress compared with the control group, controlling for age. Patients in the intervention group had higher hydroxyproline deposition in the wound than did control group patients (difference in means 0.35, 95% CI 0.66-0.03; t(43)=2.23, p=0.03). Changes in perceived stress were not associated with hydroxyproline deposition. A brief relaxation intervention prior to surgery can reduce stress and improve the wound healing response in surgical patients. The intervention may have particular clinical application for those at risk of poor healing following surgery.

Clinical supervisor evaluations during general surgery clerkships.

BACKGROUND: Clerkship performance is commonly evaluated by consultant surgeons who seldom supervise medical students directly. In contrast, surgical residents and interns frequently supervise students and provide essential teaching but are not tasked with evaluating them. AIM: To prospectively investigate and compare the accuracy of general surgery clerkship performance evaluations by clinical supervisors of differing seniorities. METHOD: Between September 2008 and May 2010, clinical supervisors of varying seniorities independently evaluated 57 fourth-year medical students using a multi-dimensional performance evaluation tool. Total evaluation grades and subtotal grades for clinical ability were correlated to the results of a validated surgical objective structured clinical examination (OSCE). RESULTS: In this study, 85 clinical supervisors provided 427 student performance evaluations. Total evaluation grades awarded by consultant surgeons had weak correlation to student OSCE results (r = 0.27, p < 0.05) and associated subtotal grades for clinical ability had no correlation. In comparison, the equivalent sets of grades awarded by residents and interns had moderate correlations to OSCE results (r = 0.49 and r = 0.54, p < 0.01). CONCLUSIONS: Validity of clinical supervisor evaluations during general surgery clerkships vary according to assessor seniority. Including performance evaluation grades by surgical residents and interns may enhance the overall validity of this common clerkship evaluation tool and improve its summative and formative assessment value.