Dissociable Contributions of Basolateral Amygdala and Ventrolateral Orbitofrontal Cortex to Flexible Learning Under Uncertainty.

Reversal learning measures the ability to form flexible associations between choice outcomes with stimuli and actions that precede them. This type of learning is thought to rely on several cortical and subcortical areas, including the highly interconnected orbitofrontal cortex (OFC) and basolateral amygdala (BLA), and is often impaired in various neuropsychiatric and substance use disorders. However, the unique contributions of these regions to stimulus- and action-based reversal learning have not been systematically compared using a chemogenetic approach particularly before and after the first reversal that introduces new uncertainty. Here, we examined the roles of ventrolateral OFC (vlOFC) and BLA during reversal learning. Male and female rats were prepared with inhibitory designer receptors exclusively activated by designer drugs targeting projection neurons in these regions and tested on a series of deterministic and probabilistic reversals during which they learned about stimulus identity or side (left or right) associated with different reward probabilities. Using a counterbalanced within-subject design, we inhibited these regions prior to reversal sessions. We assessed initial and pre-/post-reversal changes in performance to measure learning and adjustments to reversals, respectively. We found that inhibition of the ventrolateral orbitofrontal cortex (vlOFC), but not BLA, eliminated adjustments to stimulus-based reversals. Inhibition of BLA, but not vlOFC, selectively impaired action-based probabilistic reversal learning, leaving deterministic reversal learning intact. vlOFC exhibited a sex-dependent role in early adjustment to action-based reversals, but not in overall learning. These results reveal dissociable roles for BLA and vlOFC in flexible learning and highlight a more crucial role for BLA in learning meaningful changes in the reward environment.

Modulated Arc Therapy for hippocampal-avoidance whole brain radiation therapy: planning comparison with intensity modulated Radiation Therapy.

This study aimed to evaluate the modulated arc therapy (mARC) technique as a planning and treatment option for hippocampal sparing whole brain radiotherapy (HS-WBRT) following the Radiation Therapy Oncology Group (RTOG) 0933 dosimetric criteria. Computed tomography (CT) and magnetic resonance imaging (MRI) were selected retrospectively for 15 patients. Two types of plans were created for each patient, namely an intensity-modulated radiation therapy (IMRT) and a mARC plan. IMRT and mARC plans were compared in terms of plan quality indices, absorbed dose to organs at risk (OARs), number of monitor units (MUs), and treatment time. All plans in both techniques were considered clinically acceptable for treatment. However, IMRT plans presented a higher conformity (p = 0.01) as well as a higher homogeneity as compared to mARC plans, but this difference was not statistically significant (p > 0.05). In terms of the preservation of the hippocampus, it was observed that the IMRT plans achieved significantly lower doses for both 100% of its volume and for its maximum dose (p < 0.001). The evaluation of the remaining OARs showed that the IMRT technique resulted in lower doses, and significant differences were observed for the following organs: left cochlea (p < 0.001), left eye (p < 0.001), right eye (p = 0.03), both lenses of the eye (p < 0.001), and right optic nerve (p = 0.02). Despite these differences, the absolute differences in all dosimetric parameters were low enough to bear any clinical relevance. A drastic (close to 65%) and significant (p < 0.001) decrease was observed in the number of MUs for the mARC plans. This resulted in a substantial decrease in treatment time (60.45%, p < 0.001). It is concluded that the mARC technique is a feasible planning and treatment solution for HS-WBRT that meets the RTOG 0933 criteria. The main advantage of using mARC over IMRT for HS-WBRT is the considerable reduction in MUs and treatment time.

Laparoscopic gastric bypass beyond age 60.

BACKGROUND: Previous reports have questioned the safety and efficacy of gastric bypass in older patients. We examine our results in the older group of patients to shed some light on the appropriateness of offering gastric bypass to senior patients. METHODS: A retrospective review of a prospectively collected database on all laparoscopic Roux-en-Y gastric bypass (LRYGBP) cases performed from March 2001 to October 2003 was conducted. Patients >60 years of age were compared to the overall group. RESULTS: A total of 550 patients underwent LRYGBP: all were completed laparoscopically. In the 527 patients <60 years of age, there were no deaths and there were 15 complications (2.8% perioperative morbidity). In the group of patients >60 years old, there were 23 patients; mean age was 64.4 years (60-75 years). There was 1 death in this group (4.3% mortality rate) and 1 postoperative complication (4.3% morbidity rate). In the >60 year group at an average of 12 months follow-up, weight loss was 43.2 kg (28.6-73.2 kg), change in BMI was 16.5 (11-23), and excess weight loss was 65% (40-110%). Also, diabetes resolved in 3 out of 4 patients (75%), obstructive sleep apnea in 2 of 3 (67%), hypercholesterolemia in 3 of 5 (60%) and hypertension resolved or improved in 10 of 11 patients (91%). CONCLUSION: While patients >60 years of age had a higher morbidity and mortality, their risk/benefit ratio was acceptable. Older patients achieve significant weight loss and resolution of obesity-associated comorbidities.

Laparoscopic evaluation of tangential abdominal gunshot wounds.

The use of laparoscopy in abdominal trauma has been proposed for several decades; however, it has not been widely used. With the advent of laparoscopic cholecystectomy, general surgeons are realizing the potential of this technique. This should result in an expanded role for laparoscopy, including the evaluation of abdominal trauma. We present a series in which laparoscopy was used in the evaluation of tangential gunshot wounds to the abdomen. Laparoscopy enabled us to demonstrate whether the missile had violated the peritoneal cavity and to avoid laparotomy in cases without peritoneal penetration.

The role of thoracoscopy in the management of retained thoracic collections after trauma.

BACKGROUND: Retained hemothorax and infected thoracic collections after trauma can be seen in up to 20% of patients initially treated with tube thoracostomy and have traditionally been treated nonoperatively, often with prolonged hospital stays. METHODS: Twenty-five patients with retained thoracic collections were reviewed. They underwent 26 thoracoscopies to evacuate undrained blood with or without infection. RESULTS: In 19 patients (76%), the collections were evacuated thoracoscopically. In 4 patients the procedure was converted to an open thoracotomy, and 2 patients required additional procedures to drain these collections. Failure of thoracoscopy correlated with the time between injury and operation and the type of collection, but not with the mechanism of injury. When thoracoscopy was performed in less than 7 days after admission, no cases of empyema were noted at operation. CONCLUSIONS: Videothoracoscopy is an accurate, safe, and reliable operative therapy to evacuate retained thoracic collections. In 90% of the patients in whom the procedure was completed, good results were obtained, reducing hospital stay and possible complications. Videothoracoscopy should be the initial treatment in trauma patients with retained thoracic collections and should be used earlier and more frequently in these patients.

Reclosure of the open abdomen.

BACKGROUND: The open abdomen technique for the treatment of diffuse peritonitis has gained acceptance. Our approach has been to use the zipper technique with daily irrigations. Once the abdominal problem has resolved, the mesh and zipper are removed. Surgeons are reluctant to reoperate on patients with such prior treatment because of the anticipation of a hostile abdomen. Our study is a retrospective review of 12 patients who were treated with the open abdomen technique. At a later date, they underwent elective reoperation. STUDY DESIGN: The charts of 12 patients were reviewed. After initial injury, the patients were in the surgical intensive care unit. Reoperations were performed nine months (mean) after discharge from this facility. The reasons for reoperation were closure of enteric fistula (five patients) and closure of an ostomy (seven patients). The abdominal wall was reconstructed in nine patients. In the other three patients, the abdomen was entered through a lateral incision and the bowel was reanastomosed. RESULTS: All of the patients survived. There were five complications. Two patients had ischemic skin grafts successfully treated by hyperbaric oxygen therapy (HBO). Two patients had ischemic skin flaps that were covering mesh. They responded to HBO with minimal slough of superficial tissue. One patient had a low output fistula that closed after two weeks of total parenteral nutrition. CONCLUSIONS: A history of an open abdomen is not a contraindication to later operation. Bowel continuity can be restored and abdominal wall reconstruction can be performed safely. This can be done as early as three to four months after recovery from the original injury.

Blunt traumatic injuries to the colon and rectum.

BACKGROUND: Experience in the treatment of patients with blunt colonic injuries is based on isolated case reports, and it is unclear whether the principles that guide the management of penetrating colonic injuries should be applied to these patients. Reviews of patients with these injuries suggest that such injuries present unique problems for diagnosis and treatment and are accompanied by excessive morbidity and mortality. STUDY DESIGN: A 42-month retrospective case series was analyzed. RESULTS: Data from 27 patients were analyzed, accounting for 8.5 percent of all colon and rectal injuries and for 0.5 percent of total blunt trauma admissions. Automobile crashes were the cause of injuries in 20 patients (74 percent). The mean Injury Severity Score was 28. All but 2 patients were operated on within 3 hours after admission. No significant difference was found in the morbidity and mortality rates based on the operation performed to manage the colonic injury. Indications for early exploration included a positive diagnostic peritoneal lavage in 23 patients, abnormal radiologic findings in 2, and positive clinical abdominal findings in the remaining 2 patients. CONCLUSIONS: Blunt colonic and rectal injuries are uncommon and pose problems for diagnosis and treatment. Associated injuries are common, and steering wheel compression of the upper abdomen as well as lap belts seem to predispose to colonic injuries. Initial diagnosis is made at the time of operation, and a thorough exploration of the abdominal cavity is important to diagnose associated injuries. Treatment must be individualized; however, based on our observations, the creation of ostomies is not mandatory for the treatment of these injuries.

Melanosis coli: a case report in a trauma patient and review of the literature.

Melanosis Coli (MC) is a benign pigmentation disorder of the colon occasionally diagnosed at endoscopy. The authors report a case of M. coli in a patient with a gunshot to the abdomen, in whom the entity produced an interesting clinical picture, and a review of the literature on this condition.

Laparoscopic patching of crack cocaine-induced perforated ulcers.

Since the advent of "crack" cocaine use in the United States as an illicit drug, crack-related perforated ulcers have been reported in the surgical literature. An ischemic process has been postulated as a cause of these perforations. As such, an acid-reducing operative procedure is not recommended. Omental patching of these ulcers has been recommended as the procedure of choice. With the advent of laparoscopic techniques in general surgery, it is now possible to perform this procedure laparoscopically. Laparoscopy may afford the advantages of reduced morbidity, decreased hospital stay, and results potentially equal to the open technique. We present three patients with crack-related perforated ulcers that have been repaired with laparoscopic-assisted patching techniques.

Laparoscopic management of achalasia.

Eight patients with achalasia were treated using laparoscopic esophagomyotomy and anterior (Dor) fundoplication. The procedures were done on patients with clinical, radiological, and manometric diagnoses of achalasia. All procedures were completed laparoscopically. Seven (88%) of the patients were eating by the 3rd postoperative day. The average hospital stay was 4.1 days (2-11 days); analgesic use was minimal. All myotomies were complete, with no patient requiring reoperation or dilation. The only complication was a mucosal laceration in one patient; this was successfully repaired laparoscopically. Follow-up from 8 to 20 months shows that swallowing is excellent in 88 per cent and good in 12 per cent of patients, and no patient requires antireflux medication. These results support minimally invasive surgical myotomy as the treatment of choice for symptomatic achalasia.

Pyloric exclusion in the management of duodenal trauma: is concomitant gastrojejunostomy necessary?

Pyloric exclusion with gastrojejunostomy (PE-GJ) has been recommended in patients with severe injuries to the pancreatoduodenal complex. Recently, the management philosophy for pancreatoduodenal injuries has been that less treatment is probably the best treatment. But whether gastrojejunostomy (GJ) should be used routinely with pyloric exclusion (PE) remains controversial. A retrospective review was conducted of patients who underwent PE at a Level I trauma center during a 36-month period. Forty-five patients had duodenal injuries and 12 of these (27%) underwent PE for management of complex duodenal injuries. Gunshot wounds were the cause of the injuries in 10 of the 12 patients (83%). Eight patients (67%) underwent PE-GJ and had a mean hospital stay of 25 days. Four patients (33%) underwent PE alone and had a mean hospital stay of 29 days. All 12 patients had spontaneous opening of the PE, regardless of the technique used. One patient (12.5%) in the PE-GJ group developed marginal ulceration and significant hemorrhage, and one patient died in the PE-GJ group. The reported incidence of marginal ulceration in the PE-GJ group, the spontaneous opening of the pylorus, and the need to limit the extent of surgical repair to focus on all other associated lesions present in these patients, suggest that GJ should not be used routinely in patients undergoing PE for the management of severe pancreatoduodenal injuries.

The relationship of burn wound fluid to serum creatinine and creatinine clearance.

A case is presented with emphasis on creatinine clearance and burn wound closure. It suggests that the burn wound acts as an extrarenal site for creatinine loss. As a result, renal creatinine clearance may be falsely elevated while the burn wound is open, and closure of the burn wound may affect creatinine clearance.

Urgent lobectomy and pneumonectomy.

A small number of trauma patients with penetrating thoracic trauma will require formal pulmonary resections to repair severe injuries or control massive haemorrhage. Although previous reports on this subject have addressed the management of these injuries in battle conditions, civilian experience with this type of chest injury is limited. In a 3-year period, 259 patients underwent urgent thoracotomies for penetrating thoracic trauma. We retrospectively reviewed 43 patients who underwent lobectomies or pneumonectomies to control bleeding (93%) or bronchial injuries (7%). Handguns were the aetiologic agent in 41 patients (95%). The most common complication, pneumonia, was seen in 21 patients (87%). Fifteen patients (62%) developed respiratory failure. The complications of wound infection, post-operative haemorrhage and empyema were seen in equal frequency in four patients (16%). Two patients (8%) developed bronchopleural fistulas. Nine pneumonectomies and 34 lobectomies were performed with mortality rates of 66% and 38%, respectively (overall mortality, 44%). Ten (53%) deaths occurred in the operating room, late deaths (2-15 days) were secondary to sepsis and multiple organ dysfunction syndrome (MODS). Currently, the management of patients with devastating thoracic injuries to the thoracic cavity is divided into two stages. First, initial resuscitation with rapid surgery to control major bleeding, cardiac tamponade, tracheal disruptions and potentially lethal air embolism is indicated. Once the life-threatening conditions have been resolved, definitive surgical procedures are performed to repair injuries to any of the thoracic structures.

Thoracoscopy in the evaluation and management of thoracic trauma.

Video-thoracoscopy was used to evaluate and manage patients after thoracic trauma. It was used in 29 patients. Indications included retained hemothorax in 16 patients, empyema in 11, evaluation for the source of thoracic bleeding in 1, and an airleak in 1. The mechanism of injury was blunt trauma in 8 cases, 10 with stab wounds, and 11 with gunshot wounds. In blunt trauma, thoracoscopy was carried out an average of 11.7 days post injury, chest tubes were removed after an average of 7 days post thoracoscopy, and discharge averaged 10.7 days after thoracoscopy. The failure rate was 12.5% with no mortality. In stab wounds, it was carried out an average of 8.8 days post injury, chest tube removal occurred after 6.1 days, and discharge averaged 7.8 days after thoracoscopy. The failure rate was 20% with no mortality. In gunshot wounds, it was carried out an average of 7.5 days after injury, chest tubes were removed after 9.9 days, and discharge averaged 16 days post thoracoscopy. The failure rate was 9% with a mortality of 9%. Overall, the failure rate for thoracoscopy was 13.8% (4/29). The mortality rate was 3.5% (1/29). It was successfully performed up to 30 days post injury. It proved to be effective in the management of empyema, evacuation of clotted hemothorax, and diagnosis of ongoing thoracic bleeding.

Homotopy semi-numerical simulation of peristaltic flow of generalised Oldroyd-B fluids with slip effects.

This investigation deals with the peristaltic flow of generalised Oldroyd-B fluids (with the fractional model) through a cylindrical tube under the influence of wall slip conditions. The analysis is carried out under the assumptions of long wavelength and low Reynolds number. Analytical approximate solutions are obtained by using the highly versatile and rigorous semi-numerical procedure known as the homotopy analysis method. It is assumed that the cross section of the tube varies sinusoidally along the length of the tube. The effects of the dominant hydromechanical parameters, i.e. fractional parameters, material constants, slip parameter, time and amplitude on the pressure difference across one wavelength, are studied. Graphical plots reveal that the influence of both fractional parameters on pressure is opposite to each other. Interesting responses to a variation in the constants are obtained. Pressure is shown to be reduced by increasing the slip parameter. Furthermore, the pressure in the case of fractional models (fractional Oldroyd-B model and fractional Maxwell model) of viscoelastic fluids is considerably more substantial than that in the corresponding classical viscoelastic models (Oldroyd-B and Maxwell models). Applications of the study arise in biophysical food processing, embryology and gastro-fluid dynamics.

Effect of processing on the nutritive value of Canavalia Jackbeans (Canavalia ensiformis L).

A comparative study of roasting, cooking with and without calcium hydroxide and extrusion cooking on the protein quality of Canavalia was conducted. The results suggested both extrusion and pressure cooking with lime to be equally effective in improving the protein quality of Canavalia and superior to pressure cooking alone and roasting, the latter effective possibly in destroying the antiphysiological factors in Canavalia but possibly also damaging its protein quality. The individual effects of roasting, cooking with different levels of calcium hydroxide, and with water under pressure at different times on the protein quality of Canavalia were also studied. These indicated a beneficial effect of calcium hydroxide added at a level of 0.45% by weight of seed, for 30 minutes under pressure. Cooking in water under pressure for 30 minutes with and without lime added was slightly better than cooking for longer periods of time. Roasting was also effective in improving the quality of Canavalia particularly when the T was adjusted at 170 degrees C, and roasting conducted for 15 minutes. A significant improvement in the protein quality of processed Canavalia was obtained by methionine supplementation.

Surgical laparoscopy: impact on the management of abdominal disorders.

Over the last 5 years, laparoscopy has revolutionized the surgical management of many abdominal disorders. Some of the problems being so treated include biliary tract disease, achalasia, gastroesophageal reflux, peptic ulcers, colonic disorders, appendicitis, and inguinal hernias. Patient acceptance is excellent and hospitalization is reduced. Safety, long-term efficacy, and cost efficiency are finally in the process of being objectively evaluated.