Power spectral analysis of the effects of epinephrine,norepinephrine, dobutamine and dopexamine on microcirculation following free tissue transfer

Background: The use of pressor drugs after microsurgical free tissue transfer remains controversial because of potential vasoconstrictor effects on the free flap. Noninvasive monitoring of free flaps with laser Doppler flowmetry may provide further information regarding the local regulation of blood flow in the flap tissues during pressor infusions. This study evaluated the effects of four commonly used pressor agents. Methods: Twenty four patients (25 data sets) undergoing head and neck cancer resection and free flap reconstruction were recruited. Epinephrine, norepinephrine, dopexamine, and dobutamine were infused in a random order at four infusion rates, after surgery, with free flap and control area (deltoid region) laser Doppler skin blood flow monitoring. Frequency analysis of the Doppler waveform was performed utilizing the time period immediately before the first drug infusion for each patient as baseline. Results: At baseline there was less power at the 0.002–0.6 Hz frequency in the flap compared with control tissue consistent with surgical denervation. At maximum epinephrine infusion rates, the control of blood flow moved toward (i.e., proportion of power increased in) the lower frequencies, as smooth muscle mediated (myogenic) control began to dominate blood flow, an effect most marked with norepinephrine. Dobutamine and dopexamine had little effect on control of blood flow. Conclusions: Denervation of free flap tissue is demonstrable using spectral analysis of laser Doppler blood flow signals. With norepinephrine the control of blood flow shifts toward low frequency vasomotion where blood flow depends mostly on average blood pressure, making it potentially the most suitable agent following free tissue transfer. © 2013 Wiley Periodicals, Inc. Microsurgery, 2013.     

Biological Advantages of Porous Hydroxyapatite Scaffold Made by Solid Freeform Fabrication for Bone Tissue Regeneration

Presently, commercially available porous bone substitutes are manufactured by the sacrificial template method, direct foaming method, and polymer replication method (PRM). However, current manufacturing methods provide only the simplest form of the bone scaffold and cannot easily control pore size. Recent developments in medical imaging technology, computer‐aided design, and solid freeform fabrication (SFF), have made it possible to accurately produce porous synthetic bone scaffolds to fit the defected bone shape. Porous scaffolds were fabricated by SFF and PRM for a comparison of physical and mechanical properties of scaffold. The suggested three‐dimensional model has interconnected cubic pores of 500 μm and its calculated porosity is 25%. Whereas hydroxyapatite scaffolds fabricated by SFF had connective macropores, those by PRM formed a closed pore external surface with internally interconnected pores. SFF was supposed to be a proper method for fabricating an interconnected macroporous network. Biocompatibility was confirmed by testing the cytotoxicity, hemolysis, irritation, sensitization, and implantation. In summary, the aim was to verify the safety and efficacy of the scaffolds by biomechanical and biological tests with the hope that this research could promote the feasibility of using the scaffolds as a bone substitute.     

Kidney Transplantation From Donors After Cardiac Death: An Initial Report of 71 Cases From China

Shortage of deceased donors is a severe problem in recent years in China especially in a culture in which brain death criteria is not widely accepted. Donation after cardiac death (DCD) has been reported to expand the donor pool despite higher rates of primary nonfunction (PNF) and delayed graft function (DGF) after transplantation. We collected 71 DCD kidney transplants performed at our hospital between February, 2007 and June, 2012 with aims to demonstrate the feasibility of DCD donation in China. All patients were followed up, and postoperative complications and graft loss were recorded. The PNF rate was 2.8%, and DGF rate was 28.2%. The 1‐ and 3‐year graft survival was 95.7% and 92.4%. In conclusion, graft survival of DCD kidney transplantation in China is excellent despite of higher rates of PNF and DGF after transplantation.     

Finite Element Modeling of Stress Distribution in Intervertebral Spacers of Different Surface Geometries

Intervertebral disc spacers using bioactive ceramics have been used to treat degenerative spinal disease. Tooth‐shaped spacers are commonly used to prevent migration, but there is a possibility of fracture when inserted or after insertion. Intervertebral disc spacers with either an isosceles triangle‐shaped tooth (T1) or a right triangle‐shaped tooth (T2) were used as a control group. The design factors for the experimental group were modified to prevent fractures induced by stress concentration, and the surfaces of the spacers were designed as either an isosceles triangle‐shaped valley (V1) or a right triangle‐shaped valley (V2). Linear analysis using finite element model (FEM) was performed, and Von Mises stress distribution was calculated by applying 1000 N of uniformly distributed load. Samples of the V2 design were made with bioactive glass‐ceramics (BGS‐7) and evaluated for compressive strength, fatigue degree, and impact strength. Von Mises stress was highest at the first tooth from the posterior side for the control group and at the center for the experimental group. Compared with the control group, the experimental group showed 18.4% and 82.5% reduction (V1 vs. T1 and V2 vs. T2, respectively) in the maximum stress at the bottom of the valleys. The FEM analysis revealed that the V2 design had the most even load distribution. The V2 samples with bioactive glass‐ceramics were evaluated for compressive strength, and all six samples were not fractured up to 24 000 N. However, the average impact strength was 19.42 kN, suggesting that momentary force caused damage at a lower load than compression with a steady speed. The BGS‐7 intervertebral disc spacer with V2 design was not fractured during the fatigue test at maximum pressure of 8000 N, R ≥10, 5 Hz, and 5 million cycles. These data confirm that the BGS‐7 spacer with the V2 design may be clinically applicable. Collectively, the modified surface geometry of the experimental group significantly lowered Von Mises stress values at the bottom of the valleys, and thus the possibility of fracture by compressive load was greatly reduced. Also, impact during insertion was confirmed to cause fracture more easily, as the impact strength was lower than the compressive strength in the experimental group.     

Leucine‐rich glioma inactivated 3 promotes HaCaT keratinocyte migration

Our finding that human skin expresses leucine‐rich glioma inactivated 3 (LGI3) raises the question of the function of this cytokine in keratinocytes. We have shown that LGI3 stimulates human HaCaT keratinocyte migration without affecting viability or proliferation. Western blot analysis showed that LGI3 induced focal adhesion kinase activation, Akt phosphorylation, and glycogen synthase kinase 3β (GSK3β) phosphorylation in these cells. Using the scratch wound assay and a modified Boyden chamber, we found that LY294002, a selective phosphatidylinositol 3‐kinase inhibitor, and LiCl, a selective GSK3β inhibitor, abolished LGI3‐induced cell migration. We tested β‐catenin levels after LGI3 treatment because the Akt‐GSK3β pathway regulates β‐catenin accumulation, and β‐catenin promotes cell migration. LGI3 treatment increased β‐catenin protein and nuclear localization, whereas LY294002 prevented LGI3‐induced focal adhesion kinase and Akt activation as well as β‐catenin accumulation. Overall, these data suggest that LGI3 stimulates HaCaT cell migration following β‐catenin accumulation through the Akt pathway.     

Retrograde Versus Antegrade Nerve Sparing During Robot-assisted Radical Prostatectomy: Which Is Better for Achieving Early Functional Recovery?

Background

Although the retrograde approach to nerve sparing (NS) aimed at maximizing NS during robot-assisted radical prostatectomy (RARP) has been described, its significant benefits compared to the antegrade approach have not yet been investigated.

Objective

To evaluate the impact of NS approaches on perioperative, pathologic, and functional outcomes.

Design, setting, and participants

Five hundred one potent (Sexual Health Inventory for Men [SHIM] score >21) men underwent bilateral full NS and were followed up for a minimum of 1 yr. After propensity score matching, 344 patients were selected and were then categorized into two groups.

Surgical procedure

RARP with antegrade NS (n = 172) or RARP with retrograde NS (n = 172).

Outcome measurements and statistical analysis

Functional outcomes were assessed using validated questionnaires. Multivariable logistic regression models were applied.

Results and limitations

Positive margin rates were similar (11.1% vs 6.9%; p = 0.192), and no correlation with the NS approach was found on regression analysis. At 3, 6, and 9 mo, the potency rate was significantly higher in the retrograde approach (65% vs 80.8% and 72.1% vs 90.1% and 85.3% vs 92.9%, respectively). The multivariable model indicated that the NS approach was an independent predictor for potency recovery at 3, 6, and 9 mo, along with age, gland size, and hyperlipidemia. After adjusting for these predictors, the hazard ratio (HR) for the retrograde relative to the antegrade approach was 2.462 (95% confidence interval [CI], 1.482–4.089; p = 0.001) at 3, 4.024 (95% CI, 2.171–7.457; p < 0.001) at 6, and 2.145 (95% CI, 1.019–4.514; p = 0.044) at 9 mo. Regarding continence, the recovery rates at each time point and the mean time to regaining it were similar, and the method of NS had no effect on multivariable analysis. The absence of randomization is a major limitation of this study.

Conclusions

In patients with normal erectile function who underwent bilateral full NS, a retrograde NS approach facilitated early recovery of potency compared to that with an antegrade NS approach without compromising cancer control.     

Sentinel node biopsy using dye and isotope double tracers in early gastric cancer

Background The results of sentinel node (SN) biopsy have been improved by the use of dye and isotope double tracers in melanoma and breast cancer. However, the usefulness of this double tracer technique has not been determined in gastric cancer. The aim of this study was to investigate the possibility of improving SN biopsy results by using double tracers in gastric cancer.Methods Sixty-four gastric adenocarcinoma patients preoperatively diagnosed as cT1N0, were enrolled in the study. ^99mTc tin colloid was injected by preoperative endoscopy, and lymphoscintigraphy was performed prior to operation. After laparotomy, isosulfan blue was intraoperatively injected using an endoscope. Blue-stained or radioactive nodes were identified and defined as SNs. Gastrectomy with D2 lymphadenectomy was performed in all patients. All dissected lymph nodes were evaluated for metastasis by hematoxylin and eosin staining and immunohistochemistry.Results SN detection rates using dye, isotope, or both tracers were 95.3%, 84.4%, and 96.9%, respectively, and their corresponding sensitivities were 52.9%, 52.9%, and 70.6%. In the pT1 subset, the sensitivity of the double tracer was 87.5%; and in a subset of tumors with diameter <4.5 cm, this was also 87.5%.Conclusions These findings confirm that SN biopsy results are improved by using double tracers in gastric cancer and suggest that SN biopsy is suitable in cases of small-sized early gastric cancer.     

Dynamic airflow limitation after topical anaesthesia of the upper airway

This prospective before-and-after observational study investigated the effect of upper airway anaesthesia on dynamic airflow. Six consenting ASA 1 adults, all authors of this study, underwent a series of spirometric measurements before and after topical anaesthesia of the upper airway using lignocaine. Peak inspiratory flow rate, forced inspiratory flow between 25% and 75% of the maximum inhaled volume, forced expiratory volume at 1 second, and forced vital capacity in the supine and sitting positions were measured. The measured inspiratory parameters were significantly reduced after lignocaine topical anaesthesia of the upper airway. Expiratory flow parameters were not affected. We conclude that topical anaesthesia of the upper airway leads to dynamic inspiratory airflow limitation.