Faculty Bibliography

BACKGROUND:The use of intraoperative carbon dioxide (CO(2)) colonoscopy during a laparoscopic colon operation is becoming more common. Simultaneous intracolonic and intraabdominal CO(2) insufflation may result in significant physiologic changes, but in-depth physiologic effects have not been studied to date. This study aimed to evaluate the physiologic changes and the overall safety of simultaneous CO(2) laparoscopy and colonoscopy. METHODS:A prospective pilot study was performed with 26 subjects (17 men and 9 women) undergoing laparoscopic surgical treatment for colorectal conditions adjunctively managed with CO(2) intraoperative colonoscopy. Surgery proceeded with CO(2) insufflation to a maximum pressure of 12 mmHg by laparoscopy and with a maximum CO(2) flow of 5 l/min via colonoscopy. Serial intra- and postoperative arterial blood gases, end-tidal CO(2), and minute ventilation were recorded during predetermined periods: during initial laparoscopy, during simultaneous colonoscopy and laparoscopy, during laparoscopy after colonoscopy, and after desufflation. RESULTS:No significant morbidity resulted from simultaneous CO(2) insufflation. Three patients had a CO(2) partial pressure (PaCO(2)) greater than 50, and one patient with a body mass index (BMI) higher than 42 kg/m(2) had a PaCO(2) greater than 50 for more than 30 min and was compensated by increasing minute ventilation. The mean pH was 7.36 in the recovery room. Postoperatively, no patient had a pH lower than 7.3, prolonged intubation, or reintubation. CONCLUSION/CONCLUSIONS:Simultaneous CO(2) colonoscopy and laparoscopy lead only to transient alterations in respiratory parameters that can be compensated. Based on these findings, simultaneous insufflation of CO(2) into the peritoneal cavity and the large bowel lumen during complex endoscopic procedures may be considered safe for most patients.

BACKGROUND: Previous studies of major depressive disorder (MDD) have focused on abnormalities in the prefrontal cortex and medial temporal regions. There has been little investigation in MDD of midbrain and subcortical regions central to reward/aversion function, such as the ventral tegmental area/substantia nigra (VTA/SN), and medial forebrain bundle (MFB). METHODOLOGY/PRINCIPAL FINDINGS: We investigated the microstructural integrity of this circuitry using diffusion tensor imaging (DTI) in 22 MDD subjects and compared them with 22 matched healthy control subjects. Fractional anisotropy (FA) values were increased in the right VT and reduced in dorsolateral prefrontal white matter in MDD subjects. Follow-up analysis suggested two distinct subgroups of MDD patients, which exhibited non-overlapping abnormalities in reward/aversion circuitry. The MDD subgroup with abnormal FA values in VT exhibited significantly greater trait anxiety than the subgroup with normal FA values in VT, but the subgroups did not differ in levels of anhedonia, sadness, or overall depression severity. CONCLUSIONS/SIGNIFICANCE: These findings suggest that MDD may be associated with abnormal microstructure in brain reward/aversion regions, and that there may be at least two subtypes of microstructural abnormalities which each impact core symptoms of depression.

Recent years have witnessed an upsurge in the usage of resting-state functional magnetic resonance imaging (fMRI) to examine functional connectivity (fcMRI), both in normal and pathological populations. Despite this increasing popularity, concerns about the psychologically unconstrained nature of the 'resting-state' remain. Across studies, the patterns of functional connectivity detected are remarkably consistent. However, the test-retest reliability for measures of resting state fcMRI measures has not been determined. Here, we quantify the test-retest reliability, using resting scans from 26 participants at 3 different time points. Specifically, we assessed intersession (>5 months apart), intrasession (<1 h apart), and multiscan (across all 3 scans) reliability and consistency for both region-of-interest and voxel-wise analyses. For both approaches, we observed modest to high reliability across connections, dependent upon 3 predictive factors: 1) correlation significance (significantly nonzero > nonsignificant), 2) correlation valence (positive > negative), and 3) network membership (default mode > task positive network). Short- and long-term measures of the consistency of global connectivity patterns were highly robust. Finally, hierarchical clustering solutions were highly reproducible, both across participants and sessions. Our findings provide a solid foundation for continued examination of resting state fcMRI in typical and atypical populations

BACKGROUND:Hand-assisted laparoscopic surgery (HALS) requires a larger incision compared with standard laparoscopic surgery (SLS). Whether this leads to more longterm complications, such as incisional hernia (IH) and small bowel obstruction (SBO), has not been studied to date. This study compares the rates of SBO and IH after HALS and SLS in patients undergoing operations for colon and rectal diseases. STUDY DESIGN/METHODS:From a colorectal database, 536 consecutive patients were identified who underwent bowel resection using HALS (n = 266) and SLS (n = 270) between 2001 to 2006. All medical records were reviewed, and all subjects were contacted by telephone for accurate followup. Statistical analysis was performed using chi-square, Fisher's exact, and Mann-Whitney U tests, where appropriate. RESULTS:Median followup was 27 months (range 1 to 72 months). Overall conversion rate was 2.2% (SLS, n = 4; HALS, n = 8). Median incision size in HALS (75 mm; range 60 to 140 mm) was larger than SLS (45 mm; range 30 to 130 mm; p < 0.01). Despite the larger wound, the incidence of IH was similar between both approaches (HALS, n = 16 [6.0%] versus SLS, n = 13 [4.8%]; p < 0.54). Rate of SBO was also comparable (HALS, n = 11 [4.1%] versus SLS, n = 20 [7.4%]; p = 0.11). Wound infections occurred similarly between both groups (HALS, n = 18 [6.8%]; SLS, n = 13 [4.8%]; p = 0.33). Converted patients had a higher rate of IH compared with nonconverted ones (25% versus 5%; p = 0.02), although the rate of SBO was similar (8.3% versus 5.7%; p = 0.51). CONCLUSIONS:HALS does not lead to more longterm complications of IH and SBO when compared with SLS for resections of the colon and rectum.

The structural effects of cocaine on neural systems mediating cognition and motivation are not well known. By comparing the thickness of neocortical and paralimbic brain regions between cocaine-dependent and matched control subjects, we found that four of 18 a priori regions involved with executive regulation of reward and attention were significantly thinner in addicts. Correlations were significant between thinner prefrontal cortex and reduced keypresses during judgment and decision making of relative preference in addicts, suggesting one basis for restricted behavioral repertoires in drug dependence. Reduced effortful attention performance in addicts also correlated with thinner paralimbic cortices. Some thickness differences in addicts were correlated with cocaine use independent of nicotine and alcohol, but addicts also showed diminished thickness heterogeneity and altered hemispheric thickness asymmetry. These observations suggest that brain structure abnormalities in addicts are related in part to drug use and in part to predisposition toward addiction.

The paper here presented was motivated by a case study involving high-dimensional and high-frequency tidal volume traces measured during induced panic attacks. The focus was to develop a procedure to determine the significance of whether a mean curve dominates another one. The key idea of the suggested method relies on preserving the order in mean while reducing the dimension of the data. The observed data matrix is projected onto a set of lower rank matrices with a positive constraint. A multivariate testing procedure is then applied in the lower dimension. We use simulated data to illustrate the statistical properties of the proposed testing procedure. Results on the case study confirm the preliminary hypothesis of the investigators and provide critical support to their overall goal of creating an experimental model of the clinical panic attack in normal subjects