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Introduction Identifying a ‘Golden Patient’ the proceeding day improves emergency theatre efficiency and overall operating capacity. Aim Use this strategy to improve theatre efficiency in our Regional Plastic Surgery Department. Methods Cycle one: Interventions: Cycle two: Cycle three: Results Cycle one: Cycle two: Cycle three: Conclusions Use of the ‘Golden Patient’ protocol improves emergency theatre efficiency with subsequent effect on overall operating capacity.

Breast cancer is the commonest cancer to affect women in developed countries and is increasing in frequency in the Western world. Approximately 50,000 women and 400 men are diagnosed with breast cancer in the United Kingdom each year. Eighty per cent of these individuals will survive for at least 5 years after diagnosis. In 2012, 11,762 women died of breast cancer in the United Kingdom. Age-standardized rates of new invasive breast cancer diagnosis have increased from 75 to 126 per 100,000 population in the United Kingdom between 1977 and 2010.

Reconstruction of soft tissue defects in lower limb fractures requiring internal fixation remains a challenging scenario with the optimal surgical treatment still debated. This study aims to recommend, and eventually redefine, surgical indications for propeller flaps reconstruction in the distal lower limb, with a particular focus on the presence or not of metalwork.A retrospective study of lower limb soft tissue reconstructions performed between January 2015 and July 2018 was carried out including all patients treated with a propeller perforator flap (PPF) with at least 6-month follow-up. Patients were further divided in 2 groups depending on the presence of metalwork fixation beneath the flap (F group, propeller on Framework; NF group, propeller with No-Framework).21 patients were retained (F group, 11 patients; NF group, 10 patients). There were no significant differences between the two groups in age, BMI, ASA scores, comorbidities or defect size. There was a statistically significant difference between the groups (p0.05) in the cumulative hospital stay with a mean cumulative hospital stay of 22 ± 9 days in the F group and 12 ± 8 days in NF group. Failures were higher where PPF were used to cover hardware material, with 3 patients requiring a major secondary procedure in F group versus 1 patient in NF group.The presence of underlying metalwork significantly reduced the margin for small, day-case revision procedures such as flap readvancement or STSG. This study emphasizes clinical intuition that whilst PPF are a useful and elegant tool in lower limb reconstruction, their use should be limited when underlying metalwork is present.

In breast reduction, traditionally the inferior pedicle (IFP) technique is considered the most performed by plastic surgeons. A growing interest for the superomedial pedicle (SMP) mammoplasty technique has been documented in literature and clinical practice. Sensory recovery of the nipple-areolar complex (NAC), final areolar shape and scarring may also have a significant impact on patient satisfaction.This study represents a retrospective multimodal analysis comparing NAC sensation and appearance outcomes in IFP and SMP wise pattern breast reductions with 2-year follow-up.From 2013 to 2017, all performed reduction mammoplasty were included and divided in two groups (IFP or SMP technique). Testing included pressure perception (Semmes-Weinstein monofilaments), NAC measurement (diameters ratio and circumference) and circumareolar scar hypertrophy assessment. Measurements were repeated at 2 weeks, 6 and 24 months postoperatively.amongst the 73 patients, 42 (58%) had SMP technique and 31 (42%) had IFP technique. Values at 6-months showed better sensory return in the SMP (p 0.01**). NAC enlargement, showed no difference between groups. However, there was a statistically significant increase in both the SMP (p 0.001***) and the IFP (p 0.01**) groups when comparing the 2-week and 24-month follow-up visits measured ratios confirming a more oval appearance over time with both techniques. Scar hypertrophy showed statistically significant reduction in both the SMP (p 0.001***) and the IFP (p 0.01**) groups over time.This 2-year follow-up study showed little difference in outcomes between the two techniques, but some advantages in NAC sensory recovery with the SMP.

Background: Prior to DIEP flap breast reconstruction, mapping the perforators of the lower abdominal wall using ultrasound, computed tomography angiography (CTA) or magnetic resonance angiography (MRA) reduces the risk of flap failure. This review aimed to investigate the additional potential benefit of a reduction in operating time. Methods: We systematically searched the literature for studies concerning adult women undergoing DIEP flap breast reconstruction, which directly compared the operating times and adverse outcomes for those with and without preoperative perforator mapping by ultrasound, CTA or MRA. Outcomes were extracted, data meta-analysed and the quality of the evidence appraised. Results: Fourteen articles were included. Preoperative perforator mapping by CTA or MRA significantly reduced operating time (mean reduction of 54 minutes [95% CI 3, 105], p = 0.04), when directly compared to DIEP flap breast reconstruction with no perforator mapping. Further, perforator mapping by CTA was superior to ultrasound, as CTA saved more time in theatre (mean reduction of 58 minutes [95% CI 25, 91], p

Background: The central round block repair is a volume displacement technique to reconstruct large wide local excision (WLE) defects in breasts with moderate ptosis or hypertrophy. There are limited published data on the outcomes of this technique. Methods: Data were collected prospectively for 57 consecutive patients and follow up information obtained from patient records. The volume of breast resection was estimated geometrically from mammography. Aesthetic outcomes were assessed from clinical measurements and panel review of patient photographs. Results: The median age was 51 [22–86] years and follow-up 5 (1.9–8.4) years. The median specimen resection weight was 50 [25–361] g and tumour size 25 [10–75] mm. Estimated volume of breast excised was 17.8% (6–31%). In total, 12/57 patients had incomplete margins: five patients had re-excision to achieve clear margins and seven required mastectomy. Two patients had local recurrence during the follow-up period, five developed distant metastases. Aesthetic data were completed for 35/50 patients. Twelve (34%) had no measurable asymmetry and 31 (89%) had a nipple position within 2 cm of the original height. Only two patients requested symmetrising surgery. Conclusions: Central round block reconstruction of large defects after WLE is a safe technique with good aesthetic outcomes. Contralateral symmetrising surgery is not usually required.

Nipple reconstructions are prone to a variable and unpredictable degree of flattening, which in some cases lead to secondary reconstruction. The use of an acellular dermal matrix (ADM) augmentation may be appropriate in cases with very thin dermis that are particularly prone to flattening or in revision cases where the first procedure has already failed. The authors present a series of 13 nipple reconstructions in ten cases. Average projection at 12 months was 51% in primary cases and 46% in secondary revision cases. This represents a better than expected long term result in a difficult cohort of patients.

Summary Introduction Implant-based breast reconstruction has relatively high complication rates. Removal of infected implants and immediate autologous reconstruction is a safe single-stage procedure that preserves the native breast skin envelope. Methods A single-centre, retrospective proof-of-concept review of all salvage procedures performed for acute/chronic infected or exposed implant-based reconstructions by a single surgeon over a 6-year period. Results We present 13 cases of a particularly difficult subgroup of acute/chronic infection/extrusion over a 6-year period. All were successfully salvaged in a single procedure by implant removal and immediate free flap reconstruction with no significant complications. All patients had a change of pocket from subpectoral to subcutaneous and partial capsulectomies. Four patients had unilateral DIEP flaps for unilateral reconstruction, 3 bi-pedicle DIEP flaps for unilateral reconstruction, 2 bilateral TUG flaps for unilateral reconstruction, 3 bilateral DIEP flaps for bilateral reconstruction and 1 unilateral DIEP and implant for unilateral reconstruction. Conclusions These patients are often slim with limited donor sites and pose technical challenges, often requiring double free flap reconstructions. Single-stage implant removal and autologous reconstruction preserves the breast skin envelope to maximise cosmesis in a single procedure. The introduction of healthy, well-vascularised tissue may also help treat the infection.

Background Perioperative hypothermia has been reported to increase the occurrence of cardiovascular complications. By increasing the activity of sympathetic nervous system, perioperative hypothermia also has the potential to increase cardiac injury and dysfunction associated with subarachnoid hemorrhage. Methods The Intraoperative Hypothermia for Aneurysm Surgery Trial randomized patients undergoing cerebral aneurysm surgery to intraoperative hypothermia (n = 499, 33.3 degrees +/- 0.8 degrees C) or normothermia (n = 501, 36.7 degrees +/- 0.5 degrees C). Cardiovascular events (hypotension, arrhythmias, vasopressor use, myocardial infarction, and others) were prospectively followed until 3-month follow-up and were compared in hypothermic and normothermic patients. A subset of 62 patients (hypothermia, n = 33; normothermia, n = 29) also had preoperative and postoperative (within 24 h) measurement of cardiac troponin-I and echocardiography to explore the association between perioperative hypothermia and subarachnoid hemorrhage-associated myocardial injury and left ventricular function. Results There was no difference between hypothermic and normothermic patients in the occurrence of any single cardiovascular event or in composite cardiovascular events. There was no difference in mortality (6%) between groups, and there was only a single primary cardiovascular death (normothermia). There was no difference between hypothermic and normothermic patients in postoperative versus preoperative left ventricular regional wall motion or ejection fraction. Compared with preoperative values, hypothermic patients had no postoperative increase in cardiac troponin-I (median change 0.00 microg/l), whereas normothermic patients had a small postoperative increase (median change + 0.01 microg/l, P = 0.038). Conclusion In patients undergoing cerebral aneurysm surgery, perioperative hypothermia was not associated with an increased occurrence of cardiovascular events.

Background Although hypothermia and barbiturates improve neurologic outcomes in animal temporary focal ischemia models, the clinical efficacy of these interventions during temporary occlusion of the cerebral vasculature during intracranial aneurysm surgery (temporary clipping) is not established. Methods A post hoc analysis of patients from the Intraoperative Hypothermia for Aneurysm Surgery Trial who underwent temporary clipping was performed. Univariate and multivariate logistic regression methods were used to test for associations between hypothermia, supplemental protective drug, and short- (24-h) and long-term (3-month) neurologic outcomes. An odds ratio more than 1 denotes better outcome. Results Patients undergoing temporary clipping (n = 441) were assigned to intraoperative hypothermia (33.3 degrees +/- 0.8 degrees C, n = 208) or normothermia (36.7 degrees +/- 0.5 degrees C, n = 233), with 178 patients also receiving supplemental protective drug (thiopental or etomidate) during temporary clipping. Three months after surgery, 278 patients (63%) had good outcome (Glasgow Outcome Score = 1). Neither hypothermia (P = 0.847; odds ratio = 1.043, 95% CI = 0.678-1.606) nor supplemental protective drug (P = 0.835; odds ratio = 1.048, 95% CI = 0.674-1.631) were associated with 3-month Glasgow Outcome Score. The effect of supplemental protective drug did not significantly vary with temperature. The effects of hypothermia and protective drug did not significantly vary with temporary clip duration. Similar findings were made for 24-h neurologic status and 3-month Neuropsychological Composite Score. Conclusion In the Intraoperative Hypothermia for Aneurysm Surgery Trial, neither systemic hypothermia nor supplemental protective drug affected short- or long-term neurologic outcomes of patients undergoing temporary clipping.

Summary Background Periorbital haemangiomas cause severe effects on visual development. They can be treated with some success, but there is currently no literature on the selection of patients for intervention. Our study aims to review all periorbital haemangioma cases in Edinburgh over the past 20 years, to set more stringent guidelines regarding the appropriate selection of patients for treatment and determine prognostic indicators of visual outcome. Methods A review of 58 patients since 1980 with significant lesions, seen by ophthalmologists and/or plastic surgeons. Results 82% of those presenting were female. The mean age of presentation was 4 months and 2 months in more serious cases. Mean follow up was for 5.6 (range 0–15) years. Loss of visual field was the most sensitive prediction of the development of visual complications (67%), but least specific (76%). Pressure on the globe and pupillary obstruction were more specific (77–100%), but less sensitive (33–50%). Conclusions Loss of visual field, partial/complete pupillary obstruction and pressure exerted on the globe are all valuable prognostic indicators. The size and position of the lesion are also relevant, but are probably due to these factors. Based on these results we recommend specific guidelines for the selection of patients for intervention.

OBJECTIVE: We examined the incidence of perioperative fever and its relationship to outcome among patients enrolled in the Intraoperative Hypothermia for Aneurysm Surgery Trial. METHODS: One thousand patients with initial World Federation of Neurological Surgeons grades of I to III undergoing clipping of intracranial aneurysms after subarachnoid hemorrhage were randomized to intraoperative normothermia (36 degrees C-37 degrees C) or hypothermia (32.5 degrees C-33.5 degrees C). Fever (> or =38.5 degrees C) and other complications (including infections) occurring between admission and discharge (or death) were recorded. Functional and neuropsychologic outcomes were assessed 3 months postoperatively. The primary outcome variable for the trial was dichotomized Glasgow Outcome Scale (good outcome versus all others). RESULTS: Fever was reported in 41% of patients. In 97% of these, fever occurred in the postoperative period. The median time from surgery to first fever was 3 days. All measures of outcome were worse in patients who developed fever, even in those without infections or who were World Federation of Neurological Surgeons grade I. Logistic regression analyses were performed to adjust for differences in preoperative factors (e.g., age, Fisher grade, initial neurological status). This demonstrated that fever continued to be significantly associated with most outcome measures, even when infection was added to the model. An alternative stepwise model selection process including all fever-related measures from the preoperative and intraoperative period (e.g., hydrocephalus, duration of surgery, intraoperative blood loss) resulted in the loss of significance for dichotomized Glasgow Outcome Scale, but significant associations between fever and several other outcome measures remained. After adding postoperative delayed ischemic neurological deficits to the model, only worsened National Institutes of Health Stroke Scale score, Barthel Activities of Daily Living index, and discharge destination (home versus other) remained independently associated with fever. CONCLUSION: These findings suggest that fever is associated with worsened outcome in surgical subarachnoid hemorrhage patients, although, because the association between fever and the primary outcome measure for the trial is dependent on the covariates used in the analysis (particularly operative events and delayed ischemic neurological deficits), we cannot rule out the possibility that fever is a marker for other events. Only a formal trial of fever treatment or prevention can address this issue.

S S69 on ANC. 9 elderly and frail patients chose to have ANC rather than SLNB to avoid a second operation. 2/9 patients in this group had positive nodes, 7 were negative for metastasis. Only 3/15 SLNB positive patient had ANC and would have benefitted from IOA. However 7/9 node negative elderly frail patients would have also benefitted with IOA by avoiding ANC with its potential complications. Conclusion: In our cohort only 10/97 (10%) patients would have benefitted from IOA. http://dx.doi.org/10.1016/j.ejso.2015.03.189 P152. Is lipomodelling after breast cancer safe? Stacey Jones, Tapan Sircar, Pilar Matey New Cross Hospital, Wolverhampton, UK Introduction: Lipomodelling is the process of relocating autologous fat and is now widely used in reconstruction following breast cancer surgery within the United Kingdom, despite limited data on long term safety and outcomes. The aim of this audit is to establish the main complications associated with lipomodelling especially the breast cancer recurrence rates. Method: We retrospectively audited 140 lipomodelling procedures carried out in a district general hospital over a 6 year period. Audit standards were based on the joint guidelines from the ABS and BAPRAS. Results: The majority of procedures 83% were performed for asymmetry after implant reconstruction followed by deformity after wide local excision in 9% of cases. Other indications included to improve soft tissue coverage after implant reconstruction (4%), to augment the volume after autologous reconstruction (3%) and lastly for contour deformity after breast reduction (1%). The number of lipomodelling procedures performed on a patient ranged from one to five sessions with 59/140 (42%) of patients only having one session. 81% of individuals did not report any recipient site complications. The main recipient site complications comprised of fat necrosis (9%), bruising (5%), pain (3%), infection (1%) and calcifications (1%). 9% of individuals had donor site complications which included bruising (6%), pain (2%) and infection (1%). 3/140 (2%) of individuals had a local recurrence. Overall, 88% of individuals had either a very good or good outcome. Conclusion: Lipomodelling after breast cancer is a safe procedure with no increase in local recurrence and providing a very good outcome. http://dx.doi.org/10.1016/j.ejso.2015.03.190 P153. Use of acellular dermal matrix (ADM) in nipple reconstruction following breast reconstruction; the ‘central-pillar technique’ Paul Thiruchelvam,MaeConcepcion, Russell Bramhall, GeraldGui 1 The Royal Marsden Hospital, London, UK The London Clinic, London, UK Introduction: A number of techniques for reconstructing the nippleareolar complex have been developed, but no single method reliably yields a consistent aesthetic result with low morbidity and durable nipple projection. In a recent retrospective study, the factor patients disliked most about their nipple reconstruction was the lack of projection. We propose the use of a nipple shaped cylinder of layered acellular dermal matrix (ADM) as an augment to nipple reconstruction. Methods: 10 patients were recruited to have nipple reconstruction following either skin sparing mastectomy, ADM and implant reconstruction or central excision. Nipple projection and diameter were recorded before, immediately after and following surgery at 6 and 12 months. Results: Of the 5 patients undergoing a nipple revision (one bilateral) e the average nipple height at the end of the procedure was 11.5mm. 12 months following revision surgery the average nipple height was 5.3mm. 3 patients had a further nipple revision between 6 and 12 months. In the nipple revision group, nipple diameter immediately following surgery was 11.5mm, and 9.2mm at 12 months. 4 patients undertaking a primary nipple reconstruction, 2 were bilateral, and of these, immediately following reconstruction the nipple height measured 10.2mm. At 12 months, the average nipple height was 5.2mm. Nipple diameter following surgery measured 10.2mm and 9.2mm at 12 months. Conclusion: We describe a case series of nipple reconstruction using an ADM as an augment, to improve durability of nipple height and diameter. Further improvements in surgical technique will hopefully result in better projection using this novel approach http://dx.doi.org/10.1016/j.ejso.2015.03.191 P154. Implant breast reconstruction with and without acellular dermal matrix e Audit and comparative analysis Velin Voynov, Sankaran Narayanan, Soni Soumian 1 The Royal Marsden NHS FT, London, UK University Hospital of North Midlands, Stoke on Trent, UK Introduction: The most common form of immediate breast reconstruction after mastectomy is implant based. Acellular dermal matrix (ADM) has become a very popular addition to this type of reconstruction. The vast majority of published data relates to an ADM product which is not in use in the UK. With this in mind we audited our initial experience with Strattice and compared the outcome to that of non-ADM implant breast reconstruction. Methods: All consecutive patients with ADM assisted implant breast reconstruction until July 2014 were retrospectively audited against ‘Oncoplastic breast reconstruction’ and ‘ADM assisted breast reconstruction’ guidelines. Furthermore a comparison was done to all non-ADM implant reconstructions. Group difference analysis and logistic regression were used to examine the data. Results: The audit showed that unplanned return to theatre (6.9%), implant loss (6.9%) and therapeutic antibiotic use (37.9%) were higher than the suggested targets. The analysis showed no significant difference between ADM and non-ADM cases for erythema, seroma, skin necrosis, infection, implant loss, re-operation, therapeutic antibiotic use, or time to start of adjuvant therapy (p > 0.05 for all). Postoperative clinic visits were increased for the ADM group and this was close to becoming statistically significant (p 1⁄4 0.053). On univariate and multivariate regression ADM was not a significant predictor for any of the above mentioned outcomes. On multivariate regression smoking was an independent predictor of infection (p 1⁄4 0.0103) and skin necrosis (p < 0.0001), and prior breast radiotherapy was an independent predictor of seroma (p 1⁄4 0.0054). Conclusions: ADM and non-ADM immediate implant breast reconstructions were comparable in terms of early postoperative complications and ADM (Strattice) did not significantly increase the complications. http://dx.doi.org/10.1016/j.ejso.2015.03.192 P155. The use of Titanium mesh (TiLOOP ) in immediate breast reconstruction; low cost, low complications Lisa Caldon, Clare Allison, Henry Cain, Joe O’Donoghue, Adam Critchley Newcastle Upon Tyne Trust, Newcastle, UK Introduction: Immediate Breast Reconstruction (IBR) is increasing. One-stage implant-based procedures are facilitated by non-autologous lower-pole coverage (Acellular dermal matrices and synthetic materials i.e. TiLOOP ). Published data regarding these materials is limited and costs vary. Methods: Consecutive series of short-term outcomes of mastectomy and definitive implant-based IBR with TiLOOP at a single institution. Patients were identified through theatre records and implant registries November 2013 to January 2015. Data was extracted from electronic

Previous studies in our laboratory on the natural killer (NK) lytic mechanism demonstrated that following interaction of target cell with effector cell, the effector cell releases NK cytotoxic factors (NKCF) that can then bind to and lyse the target cell. This study investigates the mechanism by which the target cell signals the effector cell to release NKCF. Studies on other cell systems with secretory functions have indicated that receptor-induced transmembrane signaling leads to the metabolism of phosphatidylinositol and activation of protein kinase C (PKC) by increased cytosolic Ca++ and diacylglycerol (DAG). We tested the hypothesis that a similar sequence of activation events occurs in human NK cells by examining the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), and the calcium ionophores A23187 and ionomycin in their ability to induce release of NKCF. The amount of NKCF released was determined in a 20-hr 51Cr release assay against an NK-sensitive target cell. A23187, ionomycin, or TPA alone did not induce release of NKCF. However, ionophores (200 mM) in conjunction with TPA (20 ng/ml) induced release of NKCF. Several properties of the induced NKCF by TPA and ionophores were concordant with those of the NK cell-mediated cytotoxicity (CMC) reaction. The kinetics of release were faster (less than 1 hr) than when either Con A or target cells were used to stimulate NKCF. Only NK-sensitive target cells were killed by NKCF. Pretreatment of effector cells with interferon enhanced release of NKCF from effector cells. Several lines of evidence suggested that the pathway of activation takes place through phosphatidyl inositol metabolism. Activation of PKC was indicated because TPA and A23187 enhanced protein phosphorylation in the LGL-enriched fraction. Experiments that made use of oleoyl acetyl glycerol, a synthetic DAG, showed release of NKCF in the absence of A23187 but was augmented by the ionophore. The above studies suggest that NKCF is released from NK effector cells within a period of time consistent with NK CMC, and the release of NKCF results either directly or indirectly from protein phosphorylation by PKC.

Studies with human U937 cells as targets established that a 15-min exposure to rTNF at pH 5.3 caused a significant increase in TNF-mediated cytolysis when compared to cells exposed to TNF at pH 7.4. A detailed examination of TNF-membrane interactions revealed that although TNF bound avidly to model membrane targets, no damage was generated under any condition tested. Binding of TNF, monitored with 125I-labeled as well as unlabeled protein, was enhanced at low pH. In the pH range tested (i.e., 4 to 8), target membrane permeability actually decreased in the presence of TNF. This membrane stabilization may be a consequence of TNF insertion into the target bilayer, a process we detected through use of an intramembranous photolabeling assay; interestingly, the efficiency of TNF insertion into membranes increased dramatically with decreasing pH. We conclude that native TNF does not cause pore formation directly and that its ability to induce cell lysis, as monitored by 51Cr release, is a consequence of some as yet obscure signaling event or intracellular activity. Parallel studies were carried out with diphtheria toxin, a protein with a more thoroughly characterized pH-dependent intoxification pathway. This toxin displayed acid-enhanced activities with both biologic and artificial targets.

A computer graphics system with refresh and storage displays, flat-bed plotter, digitizer and film recorder is described. The software structure comprises a device-independent, front-end graphics package and a driver program for each device. Two and three-dimensional vectors, hardware and software characters, transformations and windowing, picture segmentation, element and segment attributes, and input from interactive tools, such as a light-pen, are supported. The extent to which the system is used by different research groups shows that this is a very cost-effective way to provide computer graphics facilities.

A brief description of the basic oxidation-reduction processes taking place in the dry cell is used to show that substitution of solid electrolytes for conventional liquid electrolytes can enhance battery miniaturization potential without sacrifice of shelf life. Previously developed solid-electrolyte batteries, however, exhibited prohibitively high internal resistance. Solid-electrolyte batteries of the type Ag-AgI-Pt, working on concentration-cell rather than conventional oxidation- reduction principles, have significantly lower internal resistance. Such cells can be made quite small (possibly down to 0.002 cm3 per cell), have apparently excellent shelf life, and are operable at 100° C. More- over, they show a recharge capability. In addition, they appear amenable to development effort leading to a thin-film, printable battery with interesting application possibilities.

Diphtheria toxin (DTx) is an extremely potent inhibitor of protein synthesis. Cell death has been generally accepted as a straightforward effect of translation inhibition. Using human U937 cells, we found that DTx intoxication leads to cytolysis; indeed, release of 51Cr- and 75Se-labeled proteins could be detected within 7 h. However, little or no cell lysis was observed over a 20-50-h period when human U937 cells were exposed to cycloheximide, amino acid-deficient medium, or metabolic poisons even though protein synthesis was rapidly inhibited to levels observed with DTx. Likewise, investigations with human K562 cells revealed full resistance to the cytolytic action of DTx over a 50-h period despite a severe reduction in translation activity. These observations establish that inhibition of protein synthesis per se is not sufficient to provoke cell lysis. A characterization of DTx-induced cytolysis revealed a long lag period (6-7 h) which could be shortened considerably by a short exposure to low pH. NH4Cl and metabolic poisons blocked the cytolytic action of DTx, indicating that endocytic uptake of toxin is required for lytic activity. Surprisingly, DTx also induced extensive internucleosomal degradation of cellular DNA, a characteristic feature of apoptosis or programmed cell death. DNA-fragmentation preceded cell lysis and did not occur in DTx-treated K562 cells or in U937 cells that were treated with the other protein synthesis inhibitors. From these observations, we conclude that DTx-mediated cytolysis is not a simple consequence of translation inhibition and that internucleosomal DNA fragmentation is a newly identified and relatively early step in the cytolytic pathway of DTx.

We have developed a simple protocol for the routine purification of essentially homogeneous human interleukin 2. The procedures applied include ammonium sulfate precipitation, ACA-54 gel filtration, ultrafiltration and chromatofocusing. The product has a molecular weight of 14 000, as determined by electrophoretic mobility, and is free of interleukin 1, interferon, granulocyte and monocyte stimulating factors, B cell growth factor and phytohemagglutinin. The method is efficient, rapid and reproduceable and provides a helpful method for preparation of IL-2 for biochemical and biological studies at moderate cost and without the use of complex equipment.

The preparation and characterization of a novel series of radioactively labeled membrane probes is described. These probes are carbohydrate derivatives of fatty acids which contain a photosensitive azide moiety at a specified distance along the alkyl chain. The function of the carbohydrate group is to restrict the azide function to the outer surface monolayer of sealed membrane systems. The azide probes have been used in several well-characterized membrane systems including erythrocyte ghosts, membrane-enveloped viruses, and artificial vesicles. Upon activation, the probes attach to integral proteins to form a stable, covalent complex which may be extracted and identified. The activation protocol is outlined and some of the preliminary results are discussed.