Application of pulsed electric field technology to skin engineering

Tissue engineering encompasses a range of techniques that direct the growth of cells into a living tissue construct for regenerative medicine applications, disease models, drug discovery, and safety testing. These techniques have been implemented to alleviate the clinical burdens of impaired healing of skin, bone, and other tissues. Construct development requires the integration of tissue-specific cells and/or an extracellular matrix-mimicking biomaterial for structural support. Production of such constructs is generally expensive and environmentally costly, thus eco-sustainable approaches should be explored. Pulsed electric field (PEF) technology is a nonthermal physical processing method commonly used in food production and biomedical applications. In this review, the key principles of PEF and the application of PEF technology for skin engineering will be discussed, with an emphasis on how PEF can be applied to skin cells to modify their behaviour, and to biomaterials to assist in their isolation or sterilisation, or to modify their physical properties. The findings indicate that the success of PEF in tissue engineering will be reliant on systematic evaluation of key parameters, such as electric field strength, and their impact on different skin cell and biomaterial types. Linking tangible input parameters to biological responses critical to healing will assist with the development of PEF as a sustainable tool for skin repair and other tissue engineering applications.

Patient-directed Volume Reduction for Emphysema: Sequential Surgical and Endobronchial Techniques

BACKGROUND

Lung volume reduction (LVR) surgery has traditionally been performed as a 1-stage bilateral procedure or staged at a predetermined interval. However to maximize the overall benefit we have allowed the patient to determine the timing of further interventions and have added endobronchial LVR into the protocol. We have reviewed the long-term outcome.

METHODS

Three hundred thirty-one LVR procedures were performed on 254 patients (median age, 61 years [range, 23-79]) with baseline predicted lung function of (mean ± SD) forced expiratory volume in 1 second 28% ± 11% and residual volume 253% ± 53%. The initial procedure was by video-assisted thoracoscopic surgery in 236 patients (unilateral, 227; bilateral, 9), by open surgery in 5, and by endobronchial valve insertion in 13. Sixty-four patients received a second and 13 a third LVR procedure. The median time interval between first and third stage was 5.8 years (range, 1.9-10) RESULTS: In the subgroup of patients who underwent staged procedures there was a significant improvement in predicted forced expiratory volume in 1 second from 28% at baseline to 34% up to 6 years. There was sustained reduction in static lung volumes up to 8 years: Predicted residual volume remained reduced from 259% to 189%. There were sustained improvements over baseline in health status: EuroQol-5D improved from 50 ± 26 to 62 ± 23 (P < .01) for up to 5 years and the Short Form 36-item questionnaire for up to 9 years. Overall 30-day mortality was 3%. Median survival was 5.6 years (95% confidence interval, 4.7-6.9).

CONCLUSIONS

A program of staged unilateral procedures of LVR has resulted in sustained benefits for up to 9 years in physiology and health status.

The role of the multidisciplinary emphysema team meeting in the provision of lung volume reduction

Despite a positive result in favour of lung volume reduction surgery (LVRS), from one of the largest randomized controlled trial in thoracic surgery, the identification of poor outcome in certain high-risk groups has resulted in a worldwide decrease in its utilization. Patient selection is the key to successful lung volume reduction which, with the advent of a range of less invasive techniques, has become more complex. The greater variety of potential therapeutic options will inevitably lead to debate amongst treating clinicians. Therefore, to be able to make an informed decision on the best treatment for an individual patient, discussion between clinicians in a multidisciplinary team (MDT) meeting is advisable. The membership of this MDT must include all specialists involved in assessment and subsequent treatment of the patient including non-medical input. There must be robust administrative organization and record of decisions together with inter-disciplinary communication of decisions. Whilst ultimately it is the patient who will benefit from the MDT, individual participants will enhance their continued professional development. The referral pathway into the MDT must be clearly defined and disseminated. Which investigations are to be performed by referrers and which by the specialist centre need to be in an agreed protocol. Specialist input may be required to interpret the results of the latest assessment tools. The decision-making process of the MDT begins with confirmation of basic selection criteria but addresses three main areas of discussion: the definition of target areas of lung for reduction; the presence of collateral, interlobar ventilation and an assessment of individualized risk and benefit. The emphysema or lung volume reduction MDT has been established in several specialist units and its benefits include an increase in referrals overall for LVR. The establishment of an MDT approach to lung volume reduction has now been incorporated into several national guidelines.

Hybrid bilobectomy for treatment of an early-stage lung cancer in a patient with severe emphysema using the benefits of lung volume reduction

Patients with resectable lung cancer and concomitant emphysema can fall outside the accepted guidelines for surgery. Lung volume reduction can improve their lung function but involves resecting an emphysematous lobe containing the tumour. Volume reduction can also be achieved by endobronchial one-way valve insertion, causing lobar collapse, but intact fissures are required. A 'hybrid bilobectomy' was performed on a 77-year-old ex-smoker with suspected T2aN0M0 bronchogenic carcinoma and severe pulmonary emphysema. The procedure consisted of endobronchial right lower lobe volume reduction and video-assisted middle lobectomy with stapled completion of the oblique fissure. Complete collapse of the right lower lobe was confirmed intraoperatively and on follow-up chest films. The recovery period was complicated by a prolonged air leak. We believe that concomitant endobronchial volume reduction of an ipsilateral lobe can facilitate video-assisted lobectomy in high-risk patients with severe emphysema. The success of endobronchial valves to achieve a hybrid bilobectomy is increased by stapled completion of fissure to prevent collateral ventilation.

Patient experience of lung volume reduction procedures for emphysema: a qualitative service improvement project

The aim of this service improvement project was to gain understanding of the patient experience of lung volume reduction surgery (LVRS) and endobronchial valve (EBV) placement, from referral through to post-discharge care.

Focus group interviews were carried out in two tertiary centres in London and Leicester, UK. Sixteen patients who had undergone lung volume reduction surgery (LVRS), endobronchial valve (EBV) placement, or both, were recruited. Prior to participation in each focus group, participants completed a questionnaire to guide and focus discussion. Thematic analysis identified common themes to the participant experience of receiving lung volume reduction interventions.

Themes included patient focus on declining health and the need to “fight” for a referral; consequences of having procedures and potential unexpected complications; and vulnerability post discharge and limited continuity of care. Participants were clear that the benefits of having had either LVRS or EBV procedures outweighed any difficulties experienced. Participants were keen to have further similar interventions if appropriate.

These data confirm the need to develop more systematic lung volume reduction pathways, provide appropriate information, and ensure that post-discharge care is optimal.

Patients feel they have to fight to get a lung volume reduction procedure; a more systematic approach is neededhttp://ow.ly/82Oy30cLORk

Individualised risk in patients undergoing lung volume reduction surgery: the Glenfield BFG score

Lung volume reduction surgery (LVRS) has been shown to be beneficial in patients with chronic obstructive pulmonary disease, but there is low uptake, partly due to perceived concerns of high operative mortality. We aimed to develop an individualised risk score following LVRS.This was a cohort study of patients undergoing LVRS. Factors independently predicting 90-day mortality and a risk prediction score were identified. Reliability of the score was tested using area under the receiver operating characteristic curve (AUROC).237 LVRS procedures were performed. The multivariate analysis factors associated independently with death were: body mass index (BMI)<18.5 kg·m^-2 (OR 2.83, p=0.059), forced expiratory volume in 1 s (FEV₁)<0.71 L (OR 5.47, p=0.011) and transfer factor of the lung for carbon monoxide (T_LCO) <20% (OR 5.56, p=0.031). A risk score was calculated and total score assigned. AUROC for the risk score was 0.80 and a better predictor than individual components (p<0.01). The score was stratified into three risk groups. Of the total patients, 46% were classified as low risk. Similar improvements in lung function and health status were seen in all groups. The score was introduced and tested in a further 71 patients. AUROC for 90-day mortality in this cohort was 0.84.It is possible to provide an individualised predictive risk score for LVRS, which may aid decision making for both clinicians and patients.

The role of the emphysema multidisciplinary team in a successful lung volume reduction surgery programme†

OBJECTIVES

Lung volume reduction surgery (LVRS) for advanced emphysema is well established, with strong evidence from the National Emphysema Treatment Trial. However, there is still reluctance to offer the procedure, and many have looked for alternative, unproven treatments. The multidisciplinary approach has been well established in treatment of lung cancer and, more recently, in coronary artery surgery. We reviewed our practice to validate the role of our multidisciplinary team approach in our LVRS programme.

METHODS

Our multidisciplinary approach employs respiratory physicians, radiologists and surgeons involved in case selection, who meet on a regular basis. Cases are selected on the basis of clinical presentation, imaging (radionuclide lung perfusion and computerized tomography) and respiratory physiology. Retrospective analysis of prospectively collected data on 633 patients referred for lung volume reduction surgery between July 1995 and July 2013.

RESULTS

Six hundred and thirty-three patients (422 male) were referred for LVRS, of whom 253 [178 male; median age 61 years (range 37-79 years)] underwent 292 LVRS procedures.There were 268 video-assisted thoracoscopic surgical procedures, of which 13 were one-stage bilateral procedures and 37 required a staged second side. Overall median hospital stay was 13 (4-197) days, during which 11 patients died. Prolonged hospital stay was associated with increasing age and with duration of air leak, which in turn was associated with diffusion capacity and forced expiratory volume in 1 s.

CONCLUSIONS

The outcomes of a successful LVRS programme are not only dependent on good surgical technique and post-operative care. Case selection and work-up by a dedicated multidisciplinary approach for emphysema patients plays an invaluable and integral part in an LVRS programme.

L-ascorbic acid improves the serum folate response to an oral dose of [6S]-5-methyltetrahydrofolic acid in healthy men

OBJECTIVE

To investigate the effect of simultaneous administration of [6S]-5-methyltetrahydrofolic acid ([6S]-5-CH(3)H(4)PteGlu) with L-ascorbic acid (L-AA) on serum folate concentrations in healthy male subjects.

SUBJECTS AND METHODS

A total of nine healthy male volunteers were recruited. Serum folate concentrations were measured before and up to 8 h after administration of each treatment (1) placebo, (2) 343 microg [6S]-5-CH(3)H(4)PteGlu), (3) 343 microg [6S]-5-CH(3)H(4)PteGlu) with 289.4 mg L-AA and (4) 343 microg [6S]-5-CH(3)H(4)PteGlu) with 973.8 mg L-AA (n=10 samples per treatment).

RESULTS

Serum folate concentrations significantly increased compared with baseline values, starting from 30 min after [6S]-5-CH(3)H(4)PteGlu administration and remained significantly higher than baseline values during the first 6 h for treatments 3 and 4, and during the first 4 h for treatment 2. Maximal serum folate responses were observed between 0.5 and 1.5 h after [6S]-5-CH(3)H(4)PteGlu consumption and significantly differed between treatments 2 and 4 (P<0.05). When [6S]-5-CH(3)H(4)PteGlu was concurrently administered with 289.4 or 973.8 mg L-AA, the total serum folate response, calculated as the area under the curve (AUC), was significantly improved (46.5+/-4.0 and 53.0+/-4.0 vs 34.3+/-3.8 h nmol/l, P<0.05). No significant difference in AUC was found between the 289.4 and the 973.8 mg L-AA treatments.

CONCLUSIONS

Administration of a physiological dose of [6S]-5-CH(3)H(4)PteGlu with L-AA significantly improved the measured serum folate response in folate saturated healthy men.

Kinetics of the stability of broccoli (Brassica oleracea Cv. Italica) myrosinase and isothiocyanates in broccoli juice during pressure/temperature treatments

The Brassicaceae plant family contains high concentrations of glucosinolates, which can be hydrolyzed by myrosinase yielding products having an anticarcinogenic activity. The pressure and temperature stabilities of endogenous broccoli myrosinase, as well as of the synthetic isothiocyanates sulforaphane and phenylethyl isothiocyanate, were studied in broccoli juice on a kinetic basis. At atmospheric pressure, kinetics of thermal (45-60 degrees C) myrosinase inactivation could be described by a consecutive step model. In contrast, only one phase of myrosinase inactivation was observed at elevated pressure (100-600 MPa) combined with temperatures from 10 up to 60 degrees C, indicating inactivation according to first-order kinetics. An antagonistic effect of pressure (up to 200 MPa) on thermal inactivation (50 degrees C and above) of myrosinase was observed indicating that pressure retarded the thermal inactivation. The kinetic parameters of myrosinase inactivation were described as inactivation rate constants (k values), activation energy (Ea values), and activation volume (Va values). On the basis of the kinetic data, a mathematical model describing the pressure and temperature dependence of myrosinase inactivation rate constants was constructed. The stability of isothiocyanates was studied at atmospheric pressure in the temperature range from 60 to 90 degrees C and at elevated pressures in the combined pressure-temperature range from 600 to 800 MPa and from 30 to 60 degrees C. It was found that isothiocyanates were relatively thermolabile and pressure stable. The kinetics of HP/T isothiocyanate degradation could be adequately described by a first-order kinetic model. The obtained kinetic information can be used for process evaluation and optimization to increase the health effect of Brassicaceae.

Is there a role for therapeutic lobectomy for emphysema?☆☆☆

OBJECTIVE

The feasibility of performing a standard lobectomy in patients with non-small cell lung cancer (NSCLC) and severe heterogeneous emphysema whose respiratory reserve is outside standard operability guidelines has been described [Edwards JG, Duthie DJR, Waller DA. Lobar volume reduction surgery: a method of increasing the lung cancer resection rate in patients with emphysema. Thorax 2001;56:791-5; Korst RJ, Ginsberg RJ, Ailawadi M, Bains MS, Downey RJ, Rusch V, Stover D. Lobectomy improves ventilatory function in selected patients with severe COPD. Ann Thorac Surg 1998;66:898-902; Carretta A, Zannini P, Puglisi A, Chiesa G, Vanzulli A, Bianchi A, Fumagalli A, Bianco S. Improvement in pulmonary function after lobectomy for non-small cell lung cancer in emphysematous patients. Eur J Cardiothorac Surg 1999;15(5):602-7]. Postoperative lung function was better than predicted, attributable to the therapeutic benefit of deflation of the hemithorax. Our aim was to determine whether the physiological benefits of this approach were superior to conventional non-anatomical lung volume reduction surgery (LVRS) in similar patients.

METHODS

A retrospective review of a single surgeon's experience identified 34 consecutive patients who underwent upper lobectomy for completely resected stage I-II NSCLC, and who had severe heterogeneous emphysema of apical distribution with a predicted postoperative FEV1 of less than 40%. Their perioperative characteristics, postoperative spirometry and survival of these cases were compared to 46 similar patients who underwent unilateral upper lobe LVRS during the same period.

RESULTS

Data expressed as median (range). LVRS patients were significantly younger (59 years [39-70] vs 67 years [48-79] p<0.001), with more severe airflow obstruction (FEV(1) %pred 24 [12-60] vs 44 [17-54] p<0.001) and more heterogenous disease ('Q' score 4 [0.5-11.5] vs 7 [1-13] p=0.001) than the lobectomy group. No significant difference was found in median survival (88 vs 53 months, p=0.06). Lobectomy patients had a shorter air leak duration (5 days [2-36] vs 9 days [1-40], p=0.02) and hospital stay (8 days [3-63] vs 13 days [6-90] p=0.01). A significant correlation was found between pre-operative Q score and percentage improvement in FEV1 (r=-0.33, p=0.02).

CONCLUSIONS

Lobectomy for lung cancer in patients in severe heterogenous chronic obstructive pulmonary disease is associated with similar improvement in airflow obstruction as conventional LVRS, but is associated with a shorter postoperative course. Lobectomy may therefore offer a therapeutic alternative to conventional LVRS in a selected population.

En-bloc chest wall and lung resection for non-small cell lung cancer. Predictors of 60-day non-cancer related mortality

OBJECTIVE

Predictors for early mortality after isolated pulmonary resection have been identified and clear guidelines regarding fitness for surgery have been produced. However, the additional risk of en-bloc chest wall resection has not been extensively studied.

AIM

We analyzed our total experience of combined chest wall and lung resection for non-small-cell lung cancer (NSCLC) to identify additional risk factors for early non-tumour related mortality.

PATIENTS AND METHODS

A retrospective review of 41 consecutive patients, with median age of 69 (range 37-84) years, operated by a single surgeon over a 4-year period. Univariate analysis was performed to assess the relationship of selected preoperative and operative variables on mortality within 2 months from surgery.

RESULTS

Low preoperative body mass index, age over 75 years, and preoperative FEV(1) of less than 70% of predicted were associated with a significantly increased 60-day mortality. In those patients with any of these risk factors 60-day mortality was 47% (8 of 17). In those with none of the above there was no mortality (of 24 patients) (P=0.0004).

DISCUSSION

En-bloc pulmonary and chest wall resection for NSCLC should be avoided in the elderly, those with limited respiratory reserve or significant weight loss. These factors render the patient highly susceptible to chest complications leading to increased mortality.

Metalloptysis: a late complication of lung volume reduction surgery

We describe three cases where patients expectorated titanium staples many months after lung volume reduction surgery (LVRS). The possible mechanisms and technical implications of this rare complication are discussed.