Method of preparing a decellularized porcine tendon using tributyl phosphate

Extracellular matrix (ECM) materials are currently utilized for soft tissue repair applications such as vascular grafts, tendon reconstruction, and hernia repair. These materials are derived from tissues such as human dermis and porcine small intestine submucosa, which must be rendered acellular to prevent disease transmission and decrease the risk of an immune response. The ideal decellularization technique removes cells and cellular remnants, but leaves the original collagen architecture intact. The tissue utilized in this study was the central tendon of the porcine diaphragm, which had not been previously investigated for soft tissue repair. Several treatments were investigated during this study including peracetic acid, TritonX-100, sodium dodecyl sulfate, and tri(n-butyl) phosphate (TnBP). Of the decellularization treatments investigated, only 1% TnBP was effective in removing cell nuclei while leaving the structure and composition of the tissue intact. Overall, the resulting acellular tissue scaffold retained the ECM composition, strength, resistance to enzymatic degradation, and biocompatibility of the original tissue, making 1% TnBP an acceptable decellularization treatment for porcine diaphragm tendon.

Materials characterization of explanted polypropylene hernia meshes

Hernia repair with prosthetic mesh significantly decreases the rate of recurrence compared with traditional, primary suture repair by reducing the tension on the edges of the wound. However, there are several complications associated with the use of mesh that may be due to the chronic inflammatory reaction to the mesh or a loss of compliance after degradation of the material. Mesh contraction and migration can also occur, sometimes resulting in a recurrent hernia. Based on the chemical structure of the polypropylene mesh material and the physiological conditions to which it is subjected, it is possible that oxidation is responsible for these changes in material properties. Oxidation would result in surface cracking, decreased melting temperature, loss of mass, and reduced compliance of the material. The objective of this study was to identify physiochemical changes in the surface and bulk properties of explanted polypropylene hernia meshes compared to pristine polypropylene mesh materials. Several characterization techniques were utilized, including scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and compliance testing. Overall, the results supported our hypothesis that oxidation is involved with the degradation of polypropylene hernia mesh materials.

Assessment of parental knowledge and attitudes toward pediatric sports-related concussions

Background:

Parents of young athletes play a major role in the identification and management of sports-related concussions. However, they are often unaware of the consequences of concussions and recommended management techniques.

Hypothesis:

This study quantitatively assessed parental understanding of concussions to identify specific populations in need of additional education. We predicted that parents with increased education and prior sports- and concussion-related experience would have more knowledge and safer attitudes toward concussions.

Study Design:

Cross-sectional survey.

Level of Evidence:

Level 5.

Methods:

Participants were parents of children brought to a pediatric hospital and 4 satellite clinics for evaluation of orthopaedic injuries. Participants completed a validated questionnaire that assessed knowledge of concussion symptoms, attitudes regarding diagnosis and return-to-play guidelines, and previous sports- and concussion-related experience.

Results:

Over 8 months, 214 parents completed surveys. Participants scored an average of 18.4 (possible, 0-25) on the Concussion Knowledge Index and 63.1 (possible, 15-75) on the Concussion Attitude Index. Attitudes were safest among white women, and knowledge increased with income and education levels. Previous sports experience did not affect knowledge or attitudes, but parents who reported experiencing an undiagnosed concussion had significantly better concussion knowledge than those who did not.

Conclusion:

Parents with low income and education levels may benefit from additional concussion-related education.

Clinical Relevance:

There exist many opportunities for improvement in parental knowledge and attitudes about pediatric sports-related concussions. Ongoing efforts to understand parental knowledge of concussions will inform the development of a strategic and tailored approach to the prevention and management of pediatric concussions.

Effect of aging on the electrocardiogram

Previous cross-sectional population studies have shown age differences in electrocardiographic wave patterns, including lower wave amplitudes and a leftward shift of the frontal plane axis in older people. However, cross-sectional results may be due to cohort differences and the data imply only that these changes actually occur in persons as they age. In order to examine electrocardiographic changes with aging in the same persons, serial recordings, obtained 10 years apart, were taken in 440 healthy male participants of the Normative Aging Study, who were 23 to 66 years old on their first examination. At examination 1, R and S wave amplitudes were smaller and frontal plane axis measurements were shifted to the left in older men. Longitudinal changes in these same variables were consistent with the cross-sectional results. In addition, the P-R and Q-T interval durations were longer, the QRS duration was shorter and the T wave amplitude was smaller at the second examination. The longitudinal rate of change of S wave amplitude varied among age groups, decreasing more in younger men. Thus, some previously described cross-sectional age differences truly represent longitudinal age trends in electrocardiographic patterns.

Characterization of heavyweight and lightweight polypropylene prosthetic mesh explants from a single patient

Although polypropylene has been used as a hernia repair material for nearly 50 years, very little science has been applied to studying the body's effect on this material. It is possible that oxidation of mesh occurs as a result of the chemical structure of polypropylene and the physiological conditions to which it is subjected; this leads to embrittlement of the material, impaired abdominal movement, and chronic pain. It is also possible that lightweight polypropylene meshes undergo less oxidation due to a reduced inflammatory reaction. The objective of this study was to characterize explanted hernia meshes using techniques such as scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and compliance testing to determine whether the mesh density of polypropylene affects the oxidative degradation of the material. The hypothesis was that heavyweight polypropylene would incite a more intense inflammatory response than lightweight polypropylene and thus undergo greater oxidative degradation. Overall, the results support this theory.

Carbon dioxide pneumoperitoneum prevents mortality from sepsis

BACKGROUND

Carbon dioxide (CO2) pneumoperitoneum has been shown to attenuate the inflammatory response after laparoscopy. This study tested the hypothesis that abdominal insufflation with CO2 improves survival in an animal model of sepsis and investigated the associated mechanism.

METHODS

The effect of CO2, helium, and air pneumoperitoneum on mortality was studied by inducing sepsis in 143 rats via intravenous injection of lipopolysaccharide (LPS). To test the protective effect of CO2 in the setting of a laparotomy, an additional 65 animals were subjected to CO2 pneumoperitoneum, helium pneumoperitoneum, or the control condition after laparotomy and intraperitoneal LPS injection. The mechanism of CO2 protection was investigated in another 84 animals. Statistical significance was determined via Kaplan-Meier analysis for survival and analysis of variance (ANOVA) for serum cytokines.

RESULTS

Among rats with LPS-induced sepsis, CO2 pneumoperitoneum increased survival to 78%, as compared with using helium pneumoperitoneum (52%; p < 0.05), air pneumoperitoneum (55%; p = 0.09), anesthesia control (50%; p < 0.05), and LPS-only control (42%; p < 0.01). Carbon dioxide insufflation also significantly increased survival over the control condition (85% vs 25%; p < 0.05) among laparotomized septic animals, whereas helium insufflation did not (65% survival). Carbon dioxide insufflation increased plasma interleukin-10 (IL-10) levels by 35% compared with helium pneumoperitoneum (p < 0.05), and by 34% compared with anesthesia control (p < 0.05) 90 min after LPS stimulation. Carbon dioxide pneumoperitoneum resulted in a threefold reduction in tumor necrosis factor-alpha (TNF-alpha) compared with helium pneumoperitoneum (p < 0.05), and a sixfold reduction with anesthesia control (p < 0.001).

CONCLUSION

Abdominal insufflation with CO2, but not helium or air, significantly reduces mortality among animals with LPS-induced sepsis. Furthermore, CO2 pneumoperitoneum rescues animals from abdominal sepsis after a laparotomy. Because IL-10 is known to downregulate TNF-alpha, the increase in IL-10 and the decrease in TNF-alpha found among the CO2-insufflated animals in our study provide evidence for a mechanism whereby CO2 pneumoperitoneum reduces mortality via IL-10-mediated downregulation of TNF-alpha.

Use of porcine dermal collagen as a prosthetic mesh in a contaminated field for ventral hernia repair: a case report

Chronic infection of a prosthetic mesh implant is a severe complication of ventral hernia repair, and mesh explantation is usually required in these cases. Biologic mesh implants have a possible role in ventral hernia repair in this setting. Here we present a case of chronic mesh infection following ventral hernia repair and the use of a biologic mesh to repair the existing defect following explantation of the infected mesh. Analysis of the explant material demonstrated possible oxidative degradation of the original polypropylene. A review of the literature follows.

Age-related reduced prefrontal-amygdala structural connectivity is associated with lower trait anxiety

OBJECTIVE

A current neuroanatomical model of anxiety posits that greater structural connectivity between the amygdala and ventral prefrontal cortex (vPFC) facilitates regulatory control over the amygdala and helps reduce anxiety. However, some neuroimaging studies have reported contradictory findings, demonstrating a positive rather than negative association between trait anxiety and amygdala-vPFC white matter integrity. To help reconcile these findings, we tested the regulatory hypothesis of anxiety circuitry using aging as a model of white matter decline in the amygdala-vPFC pathway.

METHODS

We used probabilistic tractography to trace connections between the amygdala and vPFC in 21 younger, 18 middle-aged, and 15 healthy older adults. The resulting tract estimates were used to extract 3 indices of white-matter integrity: fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). The relationship between these amygdala-vPFC structural connectivity measures and age and State-Trait Anxiety Inventory (STAI) scores were assessed.

RESULTS

The tractography results revealed age-related decline in the FA (p = .005) and radial diffusivity (p = .002) of the amygdala-vPFC pathway. Contrary to the regulatory hypothesis, we found a positive rather than negative association between trait anxiety and right amygdala-vPFC FA (p = .01).

CONCLUSION

These findings argue against the notion that greater amygdala-vPFC structural integrity facilitates better anxiety outcomes in healthy adults. Instead, our results suggest that white matter degeneration in this network relates to lower anxiety in older adults.

Locus coeruleus MRI contrast is associated with cortical thickness in older adults

There is growing evidence that neuronal integrity of the noradrenergic locus coeruleus (LC) is important for later-life cognition. Less understood is how LC integrity relates to brain correlates of cognition, such as brain structure. Here, we examined the relationship between cortical thickness and a measure reflecting LC integrity in older (n = 229) and younger adults (n = 67). Using a magnetic resonance imaging sequence which yields high signal intensity in the LC, we assessed the contrast between signal intensity of the LC and that of neighboring pontine reference tissue. The Freesurfer software suite was used to quantify cortical thickness. LC contrast was positively related to cortical thickness in older adults, and this association was prominent in parietal, frontal, and occipital regions. Brain regions where LC contrast was related to cortical thickness include portions of the frontoparietal network which have been implicated in noradrenergically modulated cognitive functions. These findings provide novel evidence for a link between LC structure and cortical brain structure in later adulthood.

Increasing coordination and responsivity of emotion-related brain regions with a heart rate variability biofeedback randomized trial

Heart rate variability is a robust biomarker of emotional well-being, consistent with the shared brain networks regulating emotion regulation and heart rate. While high heart rate oscillatory activity clearly indicates healthy regulatory brain systems, can increasing this oscillatory activity also enhance brain function? To test this possibility, we randomly assigned 106 young adult participants to one of two 5-week interventions involving daily biofeedback that either increased heart rate oscillations (Osc+ condition) or had little effect on heart rate oscillations (Osc- condition) and examined effects on brain activity during rest and during regulating emotion. While there were no significant changes in the right amygdala-medial prefrontal cortex (MPFC) functional connectivity (our primary outcome), the Osc+ intervention increased left amygdala-MPFC functional connectivity and functional connectivity in emotion-related resting-state networks during rest. It also increased down-regulation of activity in somatosensory brain regions during an emotion regulation task. The Osc- intervention did not have these effects. In this healthy cohort, the two conditions did not differentially affect anxiety, depression, or mood. These findings indicate that modulating heart rate oscillatory activity changes emotion network coordination in the brain.

Degenerate and specific PCR assays for the detection of bovine leukaemia virus and primate T cell leukaemia/lymphoma virus pol DNA and RNA: phylogenetic comparisons of amplified sequences from cattle and primates from around the world

Degenerate and specific PCR assays were developed for bovine leukaemia virus (BLV) and/or primate T cell leukaemia/lymphoma viruses (PTLV). The degenerate assays detected all major variants of the BLV/PTLV genus at a sensitivity of 10-100 copies of input DNA; the specific systems detected 1-10 copies of input target. Sensitivity was 100% in specific DNA-PCR assays done on peripheral blood from seropositive BLV-infected cattle and HTLV-I- or HTLV-II-infected humans, and 62% in RNA/DNA-PCR assays on sera from BLV seropositive cattle. The pol fragments from 21 different BLV strains, isolated from cattle in North and Central America, were cloned and sequenced, and compared to other published BLV and PTLV pol sequences. BLV and PTLV sequences differed by 42%. Sequence divergence was up to 6% among the BLV strains, and up to 36% among the PTLV strains (with PTLV-I and PTLV-II differing among themselves by 15% and 8%, respectively). Some cows were infected with several BLV strains. Among retroviruses, BLV and PTLV sequences formed a distinct clade. The data support the interpretation that BLV and PTLV evolved from a common ancestor many millennia ago, and some considerable time before the PTLV-I and PTLV-II strains diverged from each other. The dissemination of the BLV strains studied probably resulted from the export of European cattle throughout the world over the last 500 years. The relatively similar mutation rates of BLV and PTLV, after their various points of divergence, suggest that there could be a much wider genetic range of BLV than has currently been defined.

Effect of irradiation on the patulin content and chemical composition of apple juice concentrate

The influence of ionizing radiation on the patulin content of apple juice concentrate was investigated. The results indicated that patulin, at an initial concentration of about 2 mg/kg, disappeared after irradiation of the concentrate with doses as low as 2.5 kGy. For lower doses, the extent of patulin degradation was proportional to the absorbed dose. Irradiation of the concentrate with doses sufficient for patulin disappearance did not change the titratable acidity, the content of reducing sugars and carbonyl compounds or the amino acid composition. The content of ascorbic acid slightly decreased and the colour of the concentrate brightened. The intensity of the patulin absorption spectra after irradiation of mycotoxin in aqueous solutions decreased.

The integrity of dopaminergic and noradrenergic brain regions is associated with different aspects of late-life memory performance

Changes in dopaminergic neuromodulation play a key role in adult memory decline. Recent research has also implicated noradrenaline in shaping late-life memory. However, it is unclear whether these two neuromodulators have distinct roles in age-related cognitive changes. Here, combining longitudinal MRI of the dopaminergic substantia nigra-ventral tegmental area (SN-VTA) and noradrenergic locus coeruleus (LC) in younger (n = 69) and older (n = 251) adults, we found that dopaminergic and noradrenergic integrity are differentially associated with memory performance. While LC integrity was related to better episodic memory across several tasks, SN-VTA integrity was linked to working memory. Longitudinally, we found that older age was associated with more negative change in SN-VTA and LC integrity. Notably, changes in LC integrity reliably predicted future episodic memory. These differential associations of dopaminergic and noradrenergic nuclei with late-life cognitive decline have potential clinical utility, given their degeneration in several age-associated diseases.

Value of the SAGES Learning Center in introducing new technology

BACKGROUND

The Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) Learning Center is a group of educational "classrooms" designed to tutor meeting attendees on specific technology-intensive content areas. The objectives of the Robotics Station were to familiarize participants with basic laparoscopic skills as implemented with surgical robotic assistance and to help them explore the benefits and drawbacks of using robotics in their institutions.

METHODS

Sixty-six volunteer surgeon attendees of the 2003 SAGES meeting representing a diverse group of backgrounds and possessing varying levels of surgical experience were directed through a series of drills on two different surgical robots. Each participant was directed through a series of three drills that practiced surgically relevant skills. Participants were given feedback on their performance. They then completed a 12-question computer-based questionnaire that surveyed their personal demographic backgrounds, their impressions of robotic surgery, and their opinions regarding the learning center's utility in educating them about new technology.

RESULTS

Sixty-eight percent of participants had never used a surgical robot, and 89% had never used a robot clinically. Eighty-eight percent of respondents found one or both robots easier to use than they had expected, and 91% found that one or both robots made simple surgical tasks easier compared to standard laparoscopy. Sixty-four percent of participants stated that they were more likely to pursue purchase of a robotic system for use in their practice as a result of their exposure to robotics in the Learning Center. After completing the Robotics Station, 80% of surgeons believed that current surgical robots are of clinical benefit. However, 71% of participants stated that surgical robotic systems priced above $500,000 would not be financially viable in their practices.

CONCLUSION

The structured learning environment used in the SAGES Learning Center fostered among participants a positive attitude toward surgical robotics. The format of their exposure to this technology at the Robotics Station also enabled participants to gauge the potential financial value of surgical robots in clinical practice. The SAGES Learning Center Robotics Station succeeded in exposing surgeons to surgical robotics in a way that helped them assess the value of this technology for their individual practices and institutions.

Assessment of the biocompatibility of two novel, bionanocomposite scaffolds in a rodent model

Two novel, bionanocomposite scaffolds were evaluated in a rodent model over the course of three months to determine whether these scaffolds possessed adequate biocompatibility characteristics to warrant further evaluation as possible tissue reconstruction scaffolds. These bionanocomposite scaffolds were comprised of amine-functionalized gold nanoparticles (AuNP) or silicon carbide nanowires (SiCNW) crosslinked to an acellular porcine diaphragm tendon. It was hypothesized that the addition of nanomaterials to the porcine tendon would also improve its biocompatibility by imparting a nanostructured surface. As early as seven days after implantation, both types of bionanocomposite scaffolds displayed evidence of granulation tissue and the beginning of scaffold remodeling with new collagen deposited by the host, and by ninety-seven days the bionanocomposite scaffolds were completely remodeled with no evidence of any adverse host tissue reaction or scar tissue formation. The AuNP bionanocomposite scaffolds exhibited accelerated scaffold remodeling compared to the SiCNW scaffolds.

Observed child restraint misuse in a large, urban community: Results from three years of inspection events

PROBLEM

Child restraints (CRs) are vital for optimizing child passenger safety and reducing the risk of pediatric injury and fatality in motor vehicle crashes. However, most CRs are installed improperly.

METHODS

This present study was an assessment of observed instances of CR misuse. Participants were recruited through advertisements for CR inspection events in Los Angeles County, California. Child Passenger Safety Technicians collected information about each child passenger, vehicle, and aspects of CR selection and installation.

RESULTS

Of 693 CRs installed upon arrival, only 3.8% were used with no instances of misuse. The most common misuses were inappropriate use of the top tether and failure to secure the seatbelt in locked mode.

CONCLUSIONS

The majority of observed CRs were installed with instances of misuse. CRs in newer vehicles were less likely to be installed in front of airbags and more likely to have the seatbelt routed inappropriately compared to those in older vehicles. Older children were more likely to be prematurely restrained in the front vehicle seat.

PRACTICAL APPLICATIONS

The majority of CRs are installed improperly. We identified specific instances of CR misuse that are common in a large, urban community and present recommendations to improve child passenger safety practices and education.

Heart rate variability (HRV) changes and cortical volume changes in a randomized trial of five weeks of daily HRV biofeedback in younger and older adults

Previous studies indicate that the structure and function of medial prefrontal cortex (PFC) and lateral orbitofrontal cortex (OFC) are associated with heart rate variability (HRV). Typically, this association is assumed to reflect the PFC's role in controlling HRV and emotion regulation, with better prefrontal structural integrity supporting greater HRV and better emotion regulation. However, as a control system, the PFC must monitor and respond to heart rate oscillatory activity. Thus, engaging in regulatory feedback during heart rate oscillatory activity may over time help shape PFC structure, as relevant circuits and connections are modified. In the current study with younger and older adults, we tested whether 5 weeks of daily sessions of biofeedback to increase heart rate oscillations (Osc+ condition) vs. to decrease heart rate oscillations (Osc- condition) affected cortical volume in left OFC and right OFC, two regions particularly associated with HRV in prior studies. The left OFC showed significant differences in volume change across conditions, with Osc+ increasing volume relative to Osc-. The volume changes in left OFC were significantly correlated with changes in mood disturbance. In addition, resting low frequency HRV increased more in the Osc+ than in the Osc- condition. These findings indicate that daily biofeedback sessions regulating heart rate oscillatory activity can shape both resting HRV and the brain circuits that help control HRV and regulate emotion.

Endoscopic colotomy closure after full thickness excision: comparison of T fastener with multiclip applier

BACKGROUND AND STUDY AIMS

Safe, reliable, and efficient endoscopic closure of a colotomy is paramount for endoscopic full thickness excision of the colon. Two newly developed devices, the Tissue Apposition System (TAS) and the InScope Multi-Clip Applier (IMCA), may help to achieve this. The aim of this study was to determine the feasibility of using each device to close colotomies after full thickness wall excisions.

MATERIAL AND METHODS

12 pigs were used in the study. After laparoscopic full thickness excision of the colonic wall, the defect was closed using either the TAS or the IMCA. Closure was performed under laparoscopic vision. Success of colotomy closure, time taken for colotomy closure, postoperative infections, and complication rates were recorded.

RESULTS

Complete closure was achieved in 6/6 pigs in the TAS group. In 5/6 pigs in the IMCA group closure was successful; in one pig laparoscopic assistance was used. Median closure time (range) was significantly lower in the TAS group at 48 minutes (15 - 51) vs. 76 minutes (43 - 145) in the IMCA group. There were no postoperative infections or complications.

CONCLUSIONS

Endoscopic closure after full thickness colonic wall excision is feasible with both the TAS and the IMCA. Closure times are significantly shorter and handling is easier with the TAS. Combined use of both systems might be beneficial.

Conjugation of gold nanoparticles to polypropylene mesh for enhanced biocompatibility

Polypropylene mesh materials have been utilized in hernia surgery for over 40 years. However, they are prone to degradation due to the body's aggressive foreign body reaction, which may cause pain or complications, forcing mesh removal from the patient. To mitigate these complications, gold nanomaterials were attached to polypropylene mesh in order to improve cellular response. Pristine samples of polypropylene mesh were exposed to hydrogen peroxide/cobalt chloride solutions to induce formation of surface carboxyl functional groups. Gold nanoparticles were covalently linked to the mesh. Scanning electron microscopy confirmed the presence of gold nanoparticles. Differential scanning calorimetry and mechanical testing confirmed that the polypropylene did not undergo any significantly detrimental changes in physicochemical properties. A WST-1 cell culture study showed an increase in cellularity on the gold nanoparticle-polypropylene mesh as compared to pristine mesh. This study showed that biocompatibility of polypropylene mesh may be improved via the conjugation of gold nanoparticles.

The effect of timing of pneumoperitoneum on the inflammatory response

BACKGROUND

We examined the effects of an identical period of pneumoperitoneum applied at three different time points after lipopolysaccharide (LPS) challenge. Two different insufflation gases were also compared.

METHODS

Male rats (n = 70) were injected intravenously with 1 mg/kg of LPS (time 0). The time relationship between a 1.5-h period of insufflation and initial LPS stimulation was the experimental variable. All rats were killed 6 h after injection. CO2 and helium insufflation were investigated. Ten control rats received LPS only. Serum interleukin-6 (IL-6) levels were determined by enzyme-linked immunosorbent assay (ELISA). Hepatic expression of alpha2-macroglobulin, beta-fibrinogen, and metallothionein were measured by Northern blot analysis. Statistical analysis was performed using one-way analysis of variance (ANOVA).

RESULTS

Expression of alpha2-macroglobulin mRNA was lower in CO2 groups compared to the control group (p < 0.05 at time 120 and 270). beta-Fibrinogen message was diminished in CO2 0 and 120 groups compared to control. Serum levels of IL-6 and expression of metallothionein mRNA did not show significant differences between groups.

CONCLUSIONS

These findings suggest that CO2 pneumoperitoneum downregulates the inflammatory response to LPS challenge. Start time of CO2 insufflation does not appear to alter hepatic expression of acute phase genes. The mechanism of alpha2-macroglobulin downregulation does not appear to be due to IL-6.

Transgastric biologic mesh delivery and abdominal wall hernia repair in a porcine model

BACKGROUND AND STUDY AIMS

Incisional abdominal wall hernias currently require repair with open or laparoscopic surgery, which is associated with wound complications and recurrent hernia formation. Natural orifice transluminal endoscopic surgery (NOTES) techniques may have the potential to decrease the morbidity associated with hernia repair. The aim of this study was to repair a chronic ventral hernia with a biologic mesh placed transgastrically in a porcine model.

MATERIALS AND METHODS

Six pigs underwent creation of an incisional abdominal wall hernia. At least 4 weeks later, transgastric repair was done using an underlay biologic mesh with at least 5 cm of overlap from the hernia fascial edge. The mesh was secured with transfascial sutures and the stomach was closed with a sutured gastropexy. Pigs were evaluated 2 weeks later by laparoscopy. Pigs were sacrificed and necropsy wa s performed 4 weeks after the repair.

RESULTS

Six pigs underwent hernia repair lasting a mean (+/- SD) of 204 +/- 123 minutes, with one perioperative death. At 2 weeks after hernia repair, laparoscopy showed significant adhesions in all pigs; one pig had extensive mesh infection and was sacrificed. Necropsy on one pig at 2 weeks and four pigs at 4 weeks showed complete coverage of the hernia defect in all pigs. All pigs had mesh abscesses or a positive mesh culture.

CONCLUSION

Transgastric repair of a chronic ventral hernia is technically feasible. Difficulties with mesh delivery and infection need to be overcome before this approach can be used in humans.

Combining independent decisions increases diagnostic accuracy of reading lumbosacral radiographs and magnetic resonance imaging

Diagnosing the causes of low back pain is a challenging task, prone to errors. A novel approach to increase diagnostic accuracy in medical decision making is collective intelligence, which refers to the ability of groups to outperform individual decision makers in solving problems. We investigated whether combining the independent ratings of chiropractors, chiropractic radiologists and medical radiologists can improve diagnostic accuracy when interpreting diagnostic images of the lumbosacral spine. Evaluations were obtained from two previously published studies: study 1 consisted of 13 raters independently rating 300 lumbosacral radiographs; study 2 consisted of 14 raters independently rating 100 lumbosacral magnetic resonance images. In both studies, raters evaluated the presence of "abnormalities", which are indicators of a serious health risk and warrant immediate further examination. We combined independent decisions of raters using a majority rule which takes as final diagnosis the decision of the majority of the group. We compared the performance of the majority rule to the performance of single raters. Our results show that with increasing group size (i.e., increasing the number of independent decisions) both sensitivity and specificity increased in both data-sets, with groups consistently outperforming single raters. These results were found for radiographs and MR image reading alike. Our findings suggest that combining independent ratings can improve the accuracy of lumbosacral diagnostic image reading.

Associations between locus coeruleus MRI contrast and physiological responses to acute stress in younger and older adults

Acute stress activates the brain's locus coeruleus (LC)-noradrenaline system. Recent studies indicate that a magnetic resonance imaging (MRI)-based measure of LC structure is associated with better cognitive outcomes in later life. Yet despite the LC's documented role in promoting physiological arousal during acute stress, no studies have examined whether MRI-assessed LC structure is related to arousal responses to acute stress. In this study, 102 younger and 51 older adults completed an acute stress induction task while we assessed multiple measures of physiological arousal (heart rate, breathing rate, systolic and diastolic blood pressure, sympathetic tone, and heart rate variability, HRV). We used turbo spin echo MRI scans to quantify LC MRI contrast as a measure of LC structure. We applied univariate and multivariate approaches to assess how LC MRI contrast was associated with arousal at rest and during acute stress reactivity and recovery. In older participants, having higher caudal LC MRI contrast was associated with greater stress-related increases in systolic blood pressure and decreases in HRV, as well as lower HRV during recovery from acute stress. These results suggest that having higher caudal LC MRI contrast in older adulthood is associated with more pronounced physiological responses to acute stress. Further work is needed to confirm these patterns in larger samples of older adults.