Current intraoperative storage and handling practices of autologous bypass conduit: A survey of the royal australasian college of surgeons.

During bypass surgery for peripheral arterial occlusive disease and ischaemic heart disease, autologous graft conduit including great saphenous veins and radial arteries are frequently stored in solution. Endothelial damage adversely affects the performance and patency of autologous bypass grafts, and intraoperative graft storage solutions have been shown to influence this process. The distribution of storage solutions currently used amongst Cardiothoracic and Vascular Surgeons from Australia and New Zealand is not well defined in the literature. The aim of this study was to determine current practices regarding autologous graft storage and handling amongst this cohort of surgeons, and discuss their potential relevance in the context of early graft failure. From this survey, the most frequently used storage solutions were heparinized saline for great saphenous veins, and pH-buffered solutions for radial arteries. Duration of storage was 30-45 min for almost half of respondents, although responses to this question were limited. Further research is required to investigate whether ischaemic endothelial injury generates a prothrombotic state, whether different storage media can alter this state, and whether this is directly associated with clinical outcomes of interest such as early graft failure.

Brain stem death induces pro-inflammatory cytokine production and cardiac dysfunction in sheep model.

INTRODUCTION: Organs procured following brain stem death (BSD) are the main source of organ grafts for transplantation. However, BSD is associated with inflammatory responses that may damage the organ and affect both the quantity and quality of organs available for transplant. Therefore, we aimed to investigate plasma and bronchoalveolar lavage (BAL) pro-inflammatory cytokine profiles and cardiovascular physiology in a clinically relevant 6-h ovine model of BSD. METHODS: Twelve healthy female sheep (37-42 Kg) were anaesthetized and mechanically ventilated prior to undergoing BSD induction and then monitored for 6 h. Plasma and BAL endothelin-1 and cytokines (IL-1ß, 6, 8 and tumour necrosis factor alpha (TNF-α)) were assessed by ELISA. Differential white blood cell counts were performed. Cardiac function during BSD was also examined using echocardiography, and cardiac biomarkers (A-type natriuretic peptide and troponin I were measured in plasma. RESULTS: Plasma concentrations big ET-1, IL-6, IL-8, TNF-α and BAL IL-8 were significantly (p < 0.01) increased over baseline at 6 h post-BSD. Increased numbers of neutrophils were observed in the whole blood (3.1 × 109 cells/L [95% confidence interval (CI) 2.06-4.14] vs. 6 × 109 cells/L [95%CI 3.92-7.97]; p < 0.01) and BAL (4.5 × 109 cells/L [95%CI 0.41-9.41] vs. 26 [95%CI 12.29-39.80]; p = 0.03) after 6 h of BSD induction vs baseline. A significant increase in ANP production (20.28 pM [95%CI 16.18-24.37] vs. 78.68 pM [95%CI 53.16-104.21]; p < 0.0001) and cTnI release (0.039 ng/mL vs. 4.26 [95%CI 2.69-5.83] ng/mL; p < 0.0001), associated with a significant reduction in heart contractile function, were observed between baseline and 6 h. CONCLUSIONS: BSD induced systemic pro-inflammatory responses, characterized by increased neutrophil infiltration and cytokine production in the circulation and BAL fluid, and associated with reduced heart contractile function in ovine model of BSD.

Endothelin receptor antagonist improves donor lung function in an ex vivo perfusion system.

BACKGROUND: A lung transplant is the last resort treatment for many patients with advanced lung disease. The majority of donated lungs come from donors following brain death (BD). The endothelin axis is upregulated in the blood and lung of the donor after BD resulting in systemic inflammation, lung damage and poor lung graft outcomes in the recipient. Tezosentan (endothelin receptor blocker) improves the pulmonary haemodynamic profile; however, it induces adverse effects on other organs at high doses. Application of ex vivo lung perfusion (EVLP) allows the development of organ-specific hormone resuscitation, to maximise and optimise the donor pool. Therefore, we investigate whether the combination of EVLP and tezosentan administration could improve the quality of donor lungs in a clinically relevant 6-h ovine model of brain stem death (BSD). METHODS: After 6 h of BSD, lungs obtained from 12 sheep were divided into two groups, control and tezosentan-treated group, and cannulated for EVLP. The lungs were monitored for 6 h and lung perfusate and tissue samples were processed and analysed. Blood gas variables were measured in perfusate samples as well as total proteins and pro-inflammatory biomarkers, IL-6 and IL-8. Lung tissues were collected at the end of EVLP experiments for histology analysis and wet-dry weight ratio (a measure of oedema). RESULTS: Our results showed a significant improvement in gas exchange [elevated partial pressure of oxygen (P = 0.02) and reduced partial pressure of carbon dioxide (P = 0.03)] in tezosentan-treated lungs compared to controls. However, the lungs hematoxylin-eosin staining histology results showed minimum lung injuries and there was no difference between both control and tezosentan-treated lungs. Similarly, IL-6 and IL-8 levels in lung perfusate showed no difference between control and tezosentan-treated lungs throughout the EVLP. Histological and tissue analysis showed a non-significant reduction in wet/dry weight ratio in tezosentan-treated lung tissues (P = 0.09) when compared to control. CONCLUSIONS: These data indicate that administration of tezosentan could improve pulmonary gas exchange during EVLP.

Acquired von Willebrand syndrome in respiratory extracorporeal life support: a systematic review of the literature.

BACKGROUND AND OBJECTIVE: Venovenous extracorporeal membrane oxygenation (VV ECMO) and extracorporeal CO2 removal (ECCO2R) are increasingly used in the management of severe respiratory failure. With bleeding complications being one of the major risks of these techniques, our aim in this systematic review was to assess the available literature on acquired von Willebrand syndrome (AvWS) and extracorporeal support. AvWS has previously been associated with bleeding and shear stress. DESIGN AND DATA SOURCES: A systematic review, using Medline via PubMed, was performed to identify eligible studies up to January 2017. RESULTS AND CONCLUSION: The prevalence of AvWF among patients on VV ECMO or ECCO2R is high, but only a limited number of studies are reported in the literature. AvWS testing should be performed, including vWF multimer analysis, vWF activity and vWF antigen concentration. The extent to which vWF contributes to bleeding during ECMO, or how much changes in ECMO management can influence high molecular weight vWF multimer levels, cannot be answered from the currently available evidence and there remains a need for future studies.

Mapping transmembrane residues of proteinase activated receptor 2 (PAR2) that influence ligand-modulated calcium signaling.

Proteinase-activated receptor 2 (PAR2) is a G protein-coupled receptor involved in metabolism, inflammation, and cancers. It is activated by proteolysis, which exposes a nascent N-terminal sequence that becomes a tethered agonist. Short synthetic peptides corresponding to this sequence also activate PAR2, while small organic molecules show promising PAR2 antagonism. Developing PAR2 ligands into pharmaceuticals is hindered by a lack of knowledge of how synthetic ligands interact with and differentially modulate PAR2. Guided by PAR2 homology modeling and ligand docking based on bovine rhodopsin, followed by cross-checking with newer PAR2 models based on ORL-1 and PAR1, site-directed mutagenesis of PAR2 was used to investigate the pharmacology of three agonists (two synthetic agonists and trypsin-exposed tethered ligand) and one antagonist for modulation of PAR2 signaling. Effects of 28 PAR2 mutations were examined for PAR2-mediated calcium mobilization and key mutants were selected for measuring ligand binding. Nineteen of twenty-eight PAR2 mutations reduced the potency of at least one ligand by >10-fold. Key residues mapped predominantly to a cluster in the transmembrane (TM) domains of PAR2, differentially influence intracellular Ca2+ induced by synthetic agonists versus a native agonist, and highlight subtly different TM residues involved in receptor activation. This is the first evidence highlighting the importance of the PAR2 TM regions for receptor activation by synthetic PAR2 agonists and antagonists. The trypsin-cleaved N-terminus that activates PAR2 was unaffected by residues that affected synthetic peptides, challenging the widespread practice of substituting peptides for proteases to characterize PAR2 physiology.

Pathway-selective antagonism of proteinase activated receptor 2.

BACKGROUND AND PURPOSE: Proteinase activated receptor 2 (PAR2) is a GPCR associated with inflammation, metabolism and disease. Clues to understanding how to block PAR2 signalling associated with disease without inhibiting PAR2 activation in normal physiology could be provided by studies of biased signalling. EXPERIMENTAL APPROACH: PAR2 ligand GB88 was profiled for PAR2 agonist and antagonist properties by several functional assays associated with intracellular G-protein-coupled signalling in vitro in three cell types and with PAR2-induced rat paw oedema in vivo. KEY RESULTS: In HT29 cells, GB88 was a PAR2 antagonist in terms of Ca(2+) mobilization and PKC phosphorylation, but a PAR2 agonist in attenuating forskolin-induced cAMP accumulation, increasing ERK1/2 phosphorylation, RhoA activation, myosin phosphatase phosphorylation and actin filament rearrangement. In CHO-hPAR2 cells, GB88 inhibited Ca(2+) release, but activated G(i/o) and increased ERK1/2 phosphorylation. In human kidney tubule cells, GB88 inhibited cytokine secretion (IL6, IL8, GM-CSF, TNF-α) mediated by PAR2. A rat paw oedema induced by PAR2 agonists was also inhibited by orally administered GB88 and compared with effects of locally administered inhibitors of G-protein coupled pathways. CONCLUSIONS AND IMPLICATIONS: GB88 is a biased antagonist of PAR2 that selectively inhibits PAR2/G(q/11)/Ca(2+)/PKC signalling, leading to anti-inflammatory activity in vivo, while being an agonist in activating three other PAR2-activated pathways (cAMP, ERK, Rho) in human cells. These findings highlight opportunities to design drugs to block specific PAR2-linked signalling pathways in disease, without blocking beneficial PAR2 signalling in normal physiology, and to dissect PAR2-associated mechanisms of disease in vivo.

Biased signalling and proteinase-activated receptors (PARs): targeting inflammatory disease.

Although it has been known since the 1960s that trypsin and chymotrypsin can mimic hormone action in tissues, it took until the 1990s to discover that serine proteinases can regulate cells by cleaving and activating a unique four-member family of GPCRs known as proteinase-activated receptors (PARs). PAR activation involves the proteolytic exposure of its N-terminal receptor sequence that folds back to function as a 'tethered' receptor-activating ligand (TL). A key N-terminal arginine in each of PARs 1 to 4 has been singled out as a target for cleavage by thrombin (PARs 1, 3 and 4), trypsin (PARs 2 and 4) or other proteases to unmask the TL that activates signalling via Gq , Gi or G12 /13 . Similarly, synthetic receptor-activating peptides, corresponding to the exposed 'TL sequences' (e.g. SFLLRN-, for PAR1 or SLIGRL- for PAR2) can, like proteinase activation, also drive signalling via Gq , Gi and G12 /13 , without requiring receptor cleavage. Recent data show, however, that distinct proteinase-revealed 'non-canonical' PAR tethered-ligand sequences and PAR-activating agonist and antagonist peptide analogues can induce 'biased' PAR signalling, for example, via G12 /13 -MAPKinase instead of Gq -calcium. This overview summarizes implications of this 'biased' signalling by PAR agonists and antagonists for the recognized roles the PARs play in inflammatory settings.

Modulating human proteinase activated receptor 2 with a novel antagonist (GB88) and agonist (GB110).

BACKGROUND AND PURPOSE: Many cells express proteinase activated receptor 2 (PAR2) on their plasma membrane. PAR2 is activated by proteolytic enzymes, such as trypsin and tryptase that cleave the receptor N-terminus, inititating signalling to intracellular G proteins. Studies on PAR2 have relied heavily upon activating effects of proteases and peptide agonists that lack stability and bioavailability in vivo. EXPERIMENTAL APPROACH: A novel small molecule agonist GB110 and an antagonist GB88 were characterized in vitro against trypsin, peptide agonists, PAR2 antibody, PAR1 agonists and flow cytometry,in seven cell lines using intracellular Ca(2+) mobilization and examined in vivo against PAR2- and PAR1-induced rat paw oedema. KEY RESULTS: GB110 is a potent non-peptidic agonist activating PAR2-mediated Ca(2+) release in HT29 cells (EC(50) ∼200 nM) and six other human cell lines, inducing PAR2 internalization. GB88 is a unique PAR2 antagonist, inhibiting PAR2 activated Ca(2+) release (IC(50) ∼2 µM) induced by native (trypsin) or synthetic peptide and non-peptide agonists. GB88 was a competitive and surmountable antagonist of agonist 2f-LIGRLO-NH(2), a competitive but insurmountable antagonist of agonist GB110, and a non-competitive insurmountable antagonist of trypsin. GB88 was orally active and anti-inflammatory in vivo, inhibiting acute rat paw oedema elicited by agonist GB110 and proteolytic or peptide agonists of PAR2 but not by corresponding agonists of PAR1 or PAR4. CONCLUSIONS AND IMPLICATIONS: The novel PAR2 agonist and antagonist modulate intracellular Ca(2+) and rat paw oedema, providing novel molecular tools for examining PAR2-mediated diseases.

Diagnosis and management of hemangiomas and vascular malformations of the head and neck.

Vascular anomalies are congenital errors in vascular development. They frequently involve the head, neck, and oral cavity. Subdivided into vascular tumors (hemangiomas) and vascular malformations, vascular anomalies remain poorly understood. However, growing interest and recent advances in the diagnosis, management, and molecular characterization of these lesions are improving treatment strategies. The role of the multidisciplinary team cannot be overstated. This review provides both basic and up-to-date knowledge on the most common vascular anomalies encountered by physicians and practitioners. Because treatment options for vascular anomalies are widely variable and often debated, this report aims to provide a comprehensive approach to these lesions based upon current concepts and practical clinical experience.

Toward a 1550 nm InGaAs photoconductive switch for terahertz generation.

We report a terahertz (THz) photoconductive switch made from a composite of metal ErAs nanoparticles embedded in In(0.53)Ga(0.47)As and coupled to a square spiral antenna. The THz output power was measured in a 77 K cryostat by using a standard hyperhemisphere-lens package, a Golay cell outside the cryostat, and a quasi-optical filter bank for spot frequency spectral measurements. Results indicate an average output power of approximately 12 microW at 22 V bias using 140 mW of optical pump power from a subpicosecond fiber mode-locked laser. In addition, the THz spectra displayed invariance to bias voltage despite operating near impact ionization.

Reflective terahertz imaging of porcine skin burns.

A reflective pulsed terahertz imaging system based on direct detection was developed and used to obtain high-resolution images of a porcine skin specimen with superficial partial-thickness (second-degree) burns. Images were also obtained of the sample through ten layers of dry medical (cotton) gauze with minimal image degradation. The burned and unburned regions of skin had large differences in terahertz reflectivity, displaying clear delineation [20 dB signal-to-noise ratio (SNR) difference signal] between both regions in the images. The terahertz images also exhibited a "halo" surrounding the burn areas that may correlate to the extent of burn injury. The system operated at a center frequency of 500 GHz with 125 GHz of 3 dB bandwidth and used whiskbroom scanning to generate images with a spatial resolution of 1.5 mm. Each pixel was acquired with a 16 ms integration time, resulting in a 40 dB postdetection SNR. The simplicity and high SNR of the reflective terahertz system are promising steps toward real-time terahertz medical imaging.

Clinical experience with HLA-B7 plasmid DNA/lipid complex in advanced squamous cell carcinoma of the head and neck.

OBJECTIVE: To investigate the safety and efficacy of alloantigen plasmid DNA therapy in patients with advanced head and neck squamous cell carcinoma using Allovectin-7 (Vical Inc, San Diego, Calif), a DNA/lipid complex designed to express the class I major histocompatibility complex antigen HLA-B7. DESIGN: Multi-institutional prospective trial. SETTING: Academic medical setting. PATIENTS: A total of 69 patients were enrolled in 3 sequential clinical trials: a single-center phase 1 trial and 2 multicenter phase 2 trials. Eligibility criteria included unresectable squamous cell carcinoma that failed conventional therapy, Karnofsky performance status score of 70 or greater, and no concurrent anticancer or immunosuppressive therapies. INTERVENTION: Patients received 2 biweekly intratumoral injections of 10 microg (phase 1 and first phase 2 trials) or 100 microg (second phase 2 trial) of Allovectin-7 followed by 4 weeks of observation. Patients with stable or responding disease after the observation period were given a second treatment cycle identical to the first. MAIN OUTCOME MEASURES: Patients were assessed for toxic effects, and tumor size was measured after cycles 1 (at 6 weeks) and 2 (at 16 weeks). RESULTS: Allovectin-7 treatment was well tolerated, with no grade 3 or 4 drug-related toxic effects. Of 69 patients treated, 23 (33%) had stable disease or a partial response after the first cycle of treatment and proceeded to the second cycle. After the second cycle, 6 patients had stable disease, 4 had a partial response, and 1 had a complete response. Responses persisted for 21 to 106 weeks. CONCLUSIONS: Intratumoral plasmid DNA immunotherapy for head and neck cancer with Allovectin-7 is safe, and further investigations are planned in patients with less advanced disease, where it could potentially improve patient survival and reduce the need for radical high-morbidity treatments.

A unique microvascular phenotype shared by juvenile hemangiomas and human placenta.

BACKGROUND: Juvenile hemangiomas are common, benign tumors, distinctive for their perinatal presentation, rapid growth during the first year of life, and subsequent involution. We recently reported that endothelia of hemangiomas highly express GLUT1, a glucose transporter normally restricted to endothelia with blood-tissue barrier function, as in brain and placenta. OBJECTIVE: To investigate possible further similarities between hemangioma and placental vessels. DESIGN: In a retrospective study of a variety of vascular tumors and anomalies, we assessed lesional immunoreactivities for the placenta-associated vascular antigens FcgammaRII, Lewis Y antigen (LeY), merosin, and GLUT1. SETTING: A university-affiliated pediatric hospital. MAIN OUTCOME MEASURE: Immunoreactivities scored for each antigen were summarized according to lesional type, compared with those of normal skin, brain, and placenta, and correlated with patient age, sex, and lesional location. RESULTS: All of 66 hemangiomas (patients aged 22 days to 7 years) showed intense immunoreactivity for FcgammaRII, merosin, LeY, and GLUT1. No immunoreactivities for these markers were seen in any of 26 vascular malformations, 4 granulation tissue specimens, 13 pyogenic granulomas, or in the tumor vasculature of 6 malignant tumors of nonvascular origin. Microvascular immunoreactivity for all 4 markers was observed in placental chorionic villi, but was absent in microvessels of normal skin and subcutis. Brain microvessels expressed only GLUT1 and merosin. CONCLUSIONS: A distinct constellation of tissue-specific markers is uniquely coexpressed by hemangiomas and placental microvessels. These findings imply a unique relationship between hemangioma and the placenta and suggest new hypotheses concerning the origin of these tumors.

The submental island flap in head and neck reconstruction.

BACKGROUND: The submental island flap (SIF) is a new alternative in the reconstruction of various head and neck defects. We present our preliminary experience in the use of this flap and describe the surgical technique. METHODS: Nine patients underwent reconstruction with the SIF between January 1998 and July 1999. The SIF has been used for the reconstruction of the cervical esophageal stenosis in 2 patients, floor of mouth and tongue defects in 6 patients, and a hemilaryngectomy defect in 1 patient. RESULTS: With the exception of one partial flap loss caused by arterial insufficiency, no flap failures were observed. All the donor site defects but one were closed primarily. One patient who underwent reconstruction of a hemilaryngectomy defect underwent revision surgery because of intractable hair growth on the transferred skin paddle. Marginal mandibular nerve function was intact in all the cases. CONCLUSIONS: When combined with the reported experience of other surgeons, our preliminary experience showed that the SIF was an excellent alternative in the reconstruction of head and neck defects because of its reliability, versatility, and relative ease of application.

Intracranial extension of inverted papilloma: An unusual and potentially fatal complication.

BACKGROUND: The purpose of this article is to define the outcome of intracranial extension of inverted papilloma and outline a rationale for management of this rare clinical presentation. METHODS: A review of patients with intracranial extension of inverted papilloma reported in the literature (18 patients), or treated in our institution (3 patients ) was performed. The data of these 21 patients were consolidated with regard to clinical presentation, treatment, and outcome. Nine patients, including 1 of our cases, had coexisting squamous cell carcinoma and therefore were excluded from the analysis. Twelve patients with "pure" inverted papilloma formed the basis of this study. RESULTS: The majority of patients (83%) with intracranial inverted papilloma had recurrent disease. Patients with extradural disease had a survival rate of 86% with an average follow-up of 4.4 years. Eighty-six percent of these survivors were treated with craniofacial resection. In contrast, 75% of patients with intradural inverted papilloma were dead of disease with an average follow-up of 9.3 months regardless of the treatment modality. CONCLUSIONS: Intracranial extension of inverted papilloma is mostly associated with recurrent disease. Intracranial extradural inverted papilloma can be effectively controlled with craniofacial resection. Intracranial intradural involvement of inverted papilloma has a poor prognosis regardless of treatment. Aggressive treatment of intranasal inverted papilloma may be the most important factor in preventing intracranial presentation.

Management of the N(0) neck.

Paramount among the challenges and controversies among the head and neck surgeon is the proper treatment of the N0 neck. Therapeutic intervention for the N0 neck usually involves any of two treatment modalities alone or in combination: surgery or radiation therapy. This article discusses the potential treatment strategies for possible subclinical neck metastasis and the rationale for their use on a site by site basis for head and neck primary tumors.

Neurotic effects of doxycycline sclerotherapy.

A patient experienced phrenic nerve paralysis after doxycycline sclerotherapy for treatment of chylous fistula at our institution. The purpose of this study is to use physiologic testing to determine whether doxycycline is capable of inducing defects in neural function. A nonrandomized, controlled trial was performed with nerve-conduction studies to determine possible deleterious effects of doxycycline sclerotherapy. Thirty-eight CD rats were used and separated into four groups. Doxycycline was applied to the sciatic nerves of rats by either topical application directly on the nerve or by intraneural injection. Nerve-conduction studies were done before surgery and at 1,7, and 21 days after surgery. The results showed a statistically significant decrement in nerve-conduction velocity and strength of transmitted impulse in those nerves injected with doxycycline solution. Complete nerve block was seen frequently. This effect was not seen with topical application of doxycycline or normal saline solution or with intraneural injection of normal saline solution. This study demonstrates that doxycycline can induce a marked decrement in neural function when applied to the subepineural layers of the sciatic nerve in the rat. Therefore doxycycline sclerotherapy should be used with great caution in situations in which it could become exposed to nerves that have sustained surgical trauma.

Histologic effect of doxycycline sclerotherapy on rat femoral nerve.

BACKGROUND: This study stems from an encounter with a phrenic nerve paralysis in a patient following doxycycline sclerotherapy for treatment of chylous fistula. The purpose of this study is to identify possible histologic evidence of doxycycline-induced nerve injury. METHODS: The femoral nerves of CD rats were used as the in vivo animal model. The nerves were exposed to varying concentrations doxycycline and normal saline was the control. The nerves were studied at several time intervals using two different staining techniques. RESULTS: The results suggest that topical doxycycline induces tissue reactions which are different from normal saline. These reactions include stimulation of a local giant cell inflammatory reaction and disruption of the myelin sheath. CONCLUSIONS: Despite the fact that this study does not give physiologic evidence of neurotoxicity, the histologic results suggest that topical doxycycline may cause nerve damage directly or indirectly. We conclude that doxycycline should not be used for sclerotherapy where unprotected nerves are exposed to the agent until further physiologic tests are performed to prove its safety.