RESUMEN

The term affordance refers to the property or quality of an object that indicates the ways in which it could potentially be used. Affordances elicit automatic motor representations that sometimes differ from the current action representation, resulting in behavioural interference effects. This affordance-induces interference could result in automatic and involuntary behavioural inhibition, probably according to the same mechanism that controls the voluntary motor inhibition. Nevertheless, few studies have considered how voluntary response inhibition is modulated by affordance. In this study, we assess the effect of affordance on voluntary action inhibition using a stop-signal task with an affordance object as a Stop Signal. An image of a mug, with the handle orientated in the same or in the opposite direction of the hand recruited to respond at the target, was used as Stop Signal. Our results showed a reduction of the time necessary to withhold the response when the handle of the mug was pointed toward the hand pre-activated to respond. This effect indicates an increased inhibition due to the mismatch between the motor representation elicited by the affordance and the motor representation pre-activated by the target. This suggests a specific interference effect, reflected in an enhanced ability to inhibit an ongoing action.

RESUMEN

The ventral premotor cortex (PMv) and primary motor cortex (M1) represent critical nodes of a parietofrontal network involved in grasping actions, such as power and precision grip. Here, we investigated how the functional PMv-M1 connectivity drives the dissociation between these two actions. We applied a PMv-M1 cortico-cortical paired associative stimulation (cc-PAS) protocol, stimulating M1 in both postero-anterior (PA) and antero-posterior (AP) directions, in order to induce long-term changes in the activity of different neuronal populations within M1. We evaluated the motor-evoked potential (MEP) amplitude, MEP latency and cortical silent period, in both PA and AP, during the isometric execution of precision and power grip, before and after the PMv-M1 cc-PAS. The repeated activation of the PMv-M1 cortico-cortical network with PA orientation over M1 did not change MEP amplitude or cortical silent period duration during both actions. In contrast, the PMv-M1 cc-PAS stimulation of M1 with an AP direction led to a specific modulation of precision grip motor drive. In particular, MEPs tested with AP stimulation showed a selective increase of corticospinal excitability during precision grip. These findings suggest that the more superficial M1 neuronal populations recruited by the PMv input are involved preferentially in the execution of precision grip actions. KEY POINTS: Ventral premotor cortex (PMv)-primary motor cortex (M1) cortico-cortical paired associative stimulation (cc-PAS) with different coil orientation targets dissociable neural populations. PMv-M1 cc-PAS with M1 antero-posterior coil orientation specifically modulates corticospinal excitability during precision grip. Superficial M1 populations are involved preferentially in the execution of precision grip. A plasticity induction protocol targeting the specific PMv-M1 subpopulation might have important translational value for the rehabilitation of hand function.

Asunto(s)

RESUMEN

The functional connection between ventral premotor cortex (PMv) and primary motor cortex (M1) is critical for the organization of goal-directed actions. Repeated activation of this connection by means of cortico-cortical paired associative stimulation (cc-PAS), a transcranial magnetic stimulation (TMS) protocol, may induce Hebbian-like plasticity. However, the physiological modifications produced by Hebbian-like plasticity in the PMv-M1 network are poorly understood. To fill this gap, we investigated the effects of cc-PAS on PMv-M1 circuits. We hypothesized that specific interactions would occur with I2 -wave interneurons as measured by the short intracortical facilitation protocol (SICF). We used different paired-pulse TMS protocols to examine the effects of PMv-M1 cc-PAS on SICF, on GABAergic circuits as measured by short (SICI) and long (LICI) intracortical inhibition protocols, and varied the current direction in M1 to target different M1 neuronal populations. Finally, we examined the effects of cc-PAS on PMv-M1 connectivity using a dual coil approach. We found that PMv-M1 cc-PAS induces both a long-term potentiation (LTP)- or long-term depression (LTD)-like after-effect in M1 neuronal activity that is strongly associated with a bidirectional-specific change in I2 -wave activity (SICF = 2.5 ms ISI). Moreover, cc-PAS induces a specific modulation of the LICI circuit and separately modulates PMv-M1 connectivity. We suggest that plasticity within the PMv-M1 circuit is mediated by a selective mechanism exerted by PMv on M1 by targeting I2 -wave interneurons. These results provide new mechanistic insights into how PMv modulates M1 activity that are relevant for the design of brain stimulation protocols in health and disease. KEY POINTS: The I2 -wave is specifically modulated by the induction of ventral premotor cortex - primary motor cortex (PMv-M1) plasticity. After PMv-M1 cortico-cortical paired associative stimulation (cc-PAS), corticospinal excitability correlates negatively with I2 -wave amplitude. Different cc-PAS coil orientations can lead to a long-term potentiation- or long-term depression-like after-effect in M1.

Asunto(s)

Asunto(s)

RESUMEN

UNLABELLED: In a prospective randomized double-blind study, we evaluated the post-operative biological and clinical effects of a single preoperative hyperbaric-treatment the day before surgery for pancreatic ductal adenocarcinoma. PATIENTS AND METHODS: Twenty one patients were randomized and divided into two groups: group-A (10 patients, 48%) were exposed to a HyperBaric Oxygen (HBO) session the day before intervention [Pre-Intervention Day (PID)], group-B (11 patients, 52%) breathed air for 40 min in a hyperbaric chamber pressurized to 1.15 ATA (placebo group). For all patients blood samples were obtained before HBO treatment or the placebo procedure (T0); at the end of HBO session or placebo procedure (T1); on the first post-operative day (POD)(T2) and on seventh POD(T3) day, measuring interleukin (IL)-1, IL-6, IL-8, IL-10, IL-12 and TNF-α, recording postoperative pancreatic fistula (POPF), biliary-fistula, fever, intra-abdominal abscess, bleeding, pulmonary complications, delayed gastric emptying and requirement for post-operative antibiotics. The results of the present pilot study suggest that a single preoperative hyperbaric oxygen treatment on the day before surgery may reduce the complication rate in pancreatic resection.

Asunto(s)

RESUMEN

BACKGROUND: Acute appendicitis is the most common emergency in abdominal surgery, but remains a continuing controversy regarding the most appropriate method of removing the inflamed appendix. MATERIALS AND METHODS: From January 2002 to December 2012, 1037 women underwent appendectomy (average age: 25±15.7 y; range: 6 to 91 y). Of these, 519 underwent open appendectomy (OA) and 518 underwent laparoscopic appendectomy (LA). For all the patients we determined the postoperative hospital stay, the eventual readmissions within 30 days after discharge, the length of surgical procedures (data were available only for the period from January 2008 to December 2012), the costs for the OA and LA, and the rate of negative appendicitis. RESULTS: In our cohort of patients, 189 women (18.2%) had a negative appendectomy. Considering the postoperative hospital stay (average: 4.2±3.6 d; range: 1 to 32 d in OA group and average: 3.9±3.1 d; range: 1 to 21 d in LA group; P=0.15) there were no statistical differences between 2 groups. The average length of surgical procedures in LA group was 42.3±18.4 minutes (range: 8 to 135 min) and 43.2±19 minutes in the OA group (range: 10 to 135 min) (P=0.63). The average net cost of LA was 1203.61 euros, whereas for OA it was 95.18 euros. In this study, we considered only the surgical materials. CONCLUSIONS: LAs are not associated with a lower complication rate than the OAs and, above all, LAs are more expensive than OAs. Also we believe that laparoscopic approach should be used only in case of unclear abdominal pain and not for the treatment of clear acute and uncomplicated appendicitis.

Asunto(s)

RESUMEN

BACKGROUND: Gemcitabine is first-line therapy for advanced pancreatic ductal adenocarcinoma (PDAC) with a poor survival and response rate. Hyperbaric oxygenation (HBO) enhances delivery of oxygen to hypoxic tumor cells and increases their susceptibility to cytotoxic effects of chemotherapy. We hypothesized that the anticancer activity of gemcitabine (GEM) may be enhanced if tumor cells are placed in an oxygen-rich environment. The present study evaluated the effects of gemcitabine, HBO and their combination on apoptosis of tumor cells. MATERIALS AND METHODS: PANC-1 and AsPc-1 PDAC tumor cell lines were used. Cultured tumor cells were treated with GEM at its growth-inhibitory concentration (IC50) and HBO at 2.5 ATA for 90 min or a combination of both (HBO then GEM and GEM then HBO). Twenty-four hours later, apoptotic cells in each group were analyzed and the apoptotic index (AI) was calculated. RESULTS: PANC-1 cell line: HBO alone had no effect on AI: 6.5 ± 0.1 vs. 5.9 ± 0.1. HBO before and after gemcitabine did not further increase AI: 8.2 ± 0.1 (HBO-GEM), 8.5 ± 0.1 (GEM-HBO) vs. 8.1 ± 0.1 (GEM). The combination of HBO and gemcitabine significantly increased AI: 10.7 ± 0.02 (p<0.001 vs. all groups). AsPc-1 cell line: HBO-alone had no effect on AI: 5.9 ± 0.1 vs. 5.9 ± 0.1. HBO before and after gemcitabine did not further increase AI: 8.2 ± 0.1 (HBO-GEM), 8.4 ± 0.1 (GEM-HBO) vs. 8.0 ± 0.1 (GEM). The combination of HBO and gemcitabine significantly increased AI: 9.7 ± 0.1 (p<0.001 vs. all groups). CONCLUSION: HBO-alone, whether administered before and after gemcitabine has no effect on apoptosis of PDAC cells in vitro. HBO significantly enhanced gemcitabine-induced apoptosis when administered during gemcitabine. Our findings suggest that the time window would be critical for using HBO as adjuvant to chemotherapy.

Asunto(s)

RESUMEN

PURPOSE: The aims of this paper were to evaluate the clinical features of patients with primary duodenal adenocarcinoma and to address the prognostic relevance of different surgical and pathological variables after potentially curative pancreaticoduodenectomy. METHODS: Patients with primary duodenal adenocarcinoma observed from 2000 through 2009 were identified from a single-institution electronic database. Univariate and multivariate analyses were performed to identify factors associated with survival. RESULTS: The study population consisted of 37 patients. Of these, 25 underwent pancreaticoduodenectomy, while the remaining 12 were not amenable to resection and underwent bypass operations or were given best supportive care. Overall survival after radical resection (R0) was significantly longer than after palliative surgery (180 versus 35 months, p = 0.013). On multivariate analysis, tumor grade (hazard ratio (HR) = 1.345, 95% CI = 1.28-1.91, p = 0.03) and the occurrence of postoperative or abdominal complications (HR = 1.781, 95% CI = 1.10-2.89, p = 0.037; HR = 1.878, 95% CI = 1.21-3.08, p = 0.029) were found to be significant prognostic factors for survival in patients undergoing potentially curative resection. In particular, median survival was 180 months in patients with an uneventful postoperative course and 52 months in those with abdominal complications. The 5-year overall survival rates were 100 and 60 %, respectively. CONCLUSIONS: According to the present findings, the development of postoperative complications may be an additional prognostic factor after potentially curative pancreaticoduodenectomy for primary duodenal adenocarcinoma. This emphasizes the need for centralization to high-volume centers where an appropriate postoperative care can be delivered.

Asunto(s)

Asunto(s)

RESUMEN

Postoperative pancreatic fistula (POPF) is the most common major complication after pancreatoduodenectomy (PD) and it can lead to prolonged hospital stay, increased costs, and mortality. The POPF rate is strictly correlated to the definition applied, but there are so many different definitions in the literature that comparison between published series of patients is difficult. The International Study Group of Pancreatic Fistula (IGSPF) has developed a new definition, with a grading system able to stratify complicated patients into three groups, based upon the clinical implications and costs of their postoperative course. The most important risk factors identified are a soft pancreatic texture and a main pancreatic duct diameter of 3 mm or less. Several surgical techniques have been studied in order to prevent anastomotic leakage, but none has been demonstrated to be superior to others. The use of somatostatin analogues is still matter of controversy. Conservative management of POPF is usually effective, but in patients with deteriorating clinical status with evidence of sepsis, surgical management is needed.

Asunto(s)

RESUMEN

AIM: Several new irreversible hydrocolloid formulations have recently become available with claims of an improved dimensional stability by the manufacturers. The aim of this study was to evaluate the accuracy of casts made from alginate impression materials poured immediately and after specific storage periods. METHODS AND MATERIALS: Five alginates were tested: CA 37 (Cavex); Jeltrate (Dentsply Caulk); Jeltrate Plus (Dentsply Latin America); Hydrogum 5 (Zhermack); and Alginoplast (Heraeus Kulzer). A master model was mounted on a special device and used to obtain the impressions. These impressions were stored at 23 degrees C and 100% relative humidity, then poured with gypsum immediately, and again after 24, 72 and 120 hours. The casts were measured and the data were analyzed by one way analysis of variance (ANOVA) and Tukey test at p<0.05. RESULTS: The dimensional stability of the alginate impressions was both material and time dependent (p<0.05). After 24 hours of storage, only Alginoplast and Hydrogum 5 comply with the master model (p>0.05). After 72 and 120 hours, only Hydrogum 5 was dimensionally stable (p>0.05). CONCLUSION: The dimensional stability of the alginate impressions is influenced by the selected material and the storage time. CLINICAL SIGNIFICANCE: Alginate impressions should generally be poured immediately. However, some new types of alginate may have the pouring delayed.

Asunto(s)

RESUMEN

Long-term survival for patients with pancreatic carcinoma is low, even following resection. Most patients who undergo curative treatment, develop recurrence usually at the same site of resection or in the liver. Failure seals the fate of the patient. Local recurrence occurs frequently; however, it is rarely a direct cause of death. In fact, most patients die from distant metastases. From a clinical point of view, it is important to distinguish recurrence from relapse. In fact, recurrence can be recognized as the reappearance of the disease in the surgical bed, often due to inadequate surgical clearance. On the other hand, the concept of relapse should be much more related to the appearance of the disease in a distant site. Both underestimated staging of the diagnosis and the biological features of the tumor can cause relapse. Up to now, there have only been a few reviews on the incidence and pattern of failure following resection. Detailed knowledge of the recurring sites of pancreatic carcinoma and study of the factors influencing disease-free survival are significant in developing neoadjuvant, surgical and adjuvant treatment. The aim of this review is to point out the major factors most commonly identified as determinants of both recurrence and relapse.

Asunto(s)