Dendritic dynamics in vivo change during neuronal maturation

In vivo imaging of optic tectal neurons in the intact Xenopus tadpole permits direct observation of the structural dynamics that occur during dendritic arbor formation. Based on images of single DiI-labeled neurons collected at daily intervals over a period of 6 d, we divided tectal cell development into three phases according to the total length of the dendritic arbor. During phase 1, the cell differentiates from a neuroepithelial cell type and extends an axon out of the tectum. The total dendritic branch length (TDBL) is <100 micrometers. During phase 2, when TDBL is 100-400 micrometers, the dendritic arbor grows rapidly. During phase 3, when TDBL is >400 micrometers, the dendritic arbor grows slowly and appears stable. Neurons at different positions along the rostrocaudal developmental axis of the tectum were imaged at 2 hr intervals over 6 hr and at 24 hr intervals over several days. Images collected at 2 hr intervals were analyzed to determine rates of branch additions and retractions. Morphologically complex, phase 3 neurons show half the rate of branch additions and retractions as phase 2 neurons. Therefore, rapidly growing neurons have dynamic dendritic arbors, and slower-growing neurons are structurally stable. The change in growth rate and dendritic arbor dynamics from phase 2 to phase 3 correlates with the developmental increase in synaptic strength in neurons located along the rostrocaudal tectal axis. The data are consistent with the idea that strong synaptic inputs stabilize dendritic arbor structures and that weaker synaptic inputs are permissive for a greater degree of dynamic rearrangements and a faster growth rate in the dendritic arbor.     

Multidisciplinary management of hilar cholangiocarcinoma (Klatskin tumor): Extended resection is associated with improved survival

Background

Effective diagnosis and treatment of patients with hilar cholangiocarcinoma (HCCA) is based on the synergy of endoscopists, interventional radiologists, radiotherapists and surgeons. This report summarizes the multidisciplinary experience in management of HCCA over a period of two decades at the Academic Medical Center in Amsterdam, with emphasis on surgical outcome.

Methods

From 1988 until 2003, 117 consecutive patients underwent resection on the suspicion of HCCA. Preoperative work-up included staging laparoscopy, preoperative biliary drainage, assessment of volume/function of future remnant liver and radiation therapy to prevent seeding metastases. More aggressive surgical approach combining hilar resection with extended liver resection was applied as of 1998. Outcomes of resection including actuarial 5-year survival were assessed.

Results

Eighteen patients (15.3%) appeared to have a benign lesion on microscopical examination of the specimen, leaving 99 patients with histologically proven HCCA. These 99 patients were analysed according to three 5-year time periods of resection, i.e. period 1 (1988-1993, n = 45), 2 (1993-1998, n = 25) and 3 (1998-2003, n = 29). The rate of R0 resections increased and actuarial five-year survival significantly improved from 20 ± 5% for the periods 1 and 2, to 33 ± 9% in period 3 (p < 0.05). Postoperative morbidity and mortality in the last period were 68% and 10%, respectively.

Conclusion

Extended surgical resection resulted in increased rate of R0 resections and significantly improved survival. Candidates for resection should be considered by a specialized, multidisciplinary team.     

Posteroanterior thoracic spinal stiffness does not change after manipulation in asymptomatic subjects

Campbell BD, Snodgrass SJ. The effect of spinal manipulation on posteroanterior thoracic stiffness. J Orthop Sports Phys Ther 2010; 40: 685–93.     

Presence and Persistence of Nutrition-Related Symptoms During the First Year Following Esophagectomy with Gastric Tube Reconstruction in Clinically Disease-Free Patients

Background  

Esophagectomy with gastric tube reconstruction results in a variety of postoperative nutrition-related symptoms that may influence the patient’s nutritional status.     

Delayed gastric emptying (DGE) after pancreatic surgery: a suggested definition by the International Study Group of Pancreatic Surgery (ISGPS)

BACKGROUND: Delayed gastric emptying (DGE) is one of the most common complications after pancreatic resection. In the literature, the reported incidence of DGE after pancreatic surgery varies considerably between different surgical centers, primarily because an internationally accepted consensus definition of DGE is not available. Several surgical centers use a different definition of DGE. Hence, a valid comparison of different study reports and operative techniques is not possible. METHODS: After a literature review on DGE after pancreatic resection, the International Study Group of Pancreatic Surgery (ISGPS) developed an objective and generally applicable definition with grades of DGE based primarily on severity and clinical impact. RESULTS: DGE represents the inability to return to a standard diet by the end of the first postoperative week and includes prolonged nasogastric intubation of the patient. Three different grades (A, B, and C) were defined based on the impact on the clinical course and on postoperative management. CONCLUSION: The proposed definition, which includes a clinical grading of DGE, should allow objective and accurate comparison of the results of future clinical trials and will facilitate the objective evaluation of novel interventions and surgical modalities in the field of pancreatic surgery.     

Cis-isomerism and other chemical requirements of steroidal agonists and partial agonists acting at TRPM3 channels

BACKGROUND AND PURPOSE

The transient receptor potential melastatin-3 (TRPM3) channel forms calcium-permeable, non-selective, cationic channels that are stimulated by pregnenolone sulphate (PregS). Here, we aimed to define chemical requirements of this acute steroid action and potentially reveal novel stimulators with physiological relevance.

EXPERIMENTAL APPROACH

We used TRPM3 channels over-expressed in HEK 293 cells, with intracellular calcium measurement and whole-cell patch-clamp recording techniques.

KEY RESULTS

The stimulation of TRPM3 channels was confined to PregS and closely related steroids and not mimicked by other major classes of steroids, including progesterone. Relatively potent stimulation of TRPM3-dependent calcium entry was observed. A sulphate group positioned at ring A was important for strong stimulation but more striking was the requirement for a cis (β) configuration of the side group, revealing previously unrecognized stereo-selectivity and supporting existence of a specific binding site. A cis-oriented side group on ring A was not the only feature necessary for high activity because loss of the double bond in ring B reduced potency and loss of the acetyl group at ring D reduced efficacy and potency. Weak steroid stimulators of TRPM3 channels inhibited effects of PregS, suggesting partial agonism. In silico screening of chemical libraries for non-steroid modulators of TRPM3 channels revealed the importance of the steroid backbone for stimulatory effects.

CONCLUSIONS AND IMPLICATIONS

Our data defined some of the chemical requirements for acute stimulation of TRPM3 channels by steroids, supporting the existence of a specific and unique steroid binding site. Epipregnanolone sulphate was identified as a novel TRPM3 channel stimulator.     

Prevention of biliary leakage after partial liver resection using topical hemostatic agents

Liver resection is widely accepted as the only potentially curative treatment in malignant or benign hepatobiliary lesions. Although not frequent, biliary leakage is a postoperative complication which may have considerable consequences. The field of topical hemostatic agents is rapidly developing, with various products currently available. This article reviews the risk factors associated with biliary leakage and the methods used for testing or prevention of biliary leakage. A literature search was performed using key words related to experimental and clinical studies dealing with biliary leakage. Experimental studies assessed the potential bilio-static effect of different topical hemostatic agents after bile duct reconstruction. Clinical series show biliary leakage rates up to 12%. There is no evidence that flushing of the bile duct system after resection reduces the incidence of biliary leakage. Further controlled studies are needed to clarify the preventive effect of topical hemostatic agents on biliary leakage after liver resection.