Quantum droplets of electrons and holes.

Interacting many-body systems are characterized by stable configurations of objects--ranging from elementary particles to cosmological formations--that also act as building blocks for more complicated structures. It is often possible to incorporate interactions in theoretical treatments of crystalline solids by introducing suitable quasiparticles that have an effective mass, spin or charge which in turn affects the material's conductivity, optical response or phase transitions. Additional quasiparticle interactions may also create strongly correlated configurations yielding new macroscopic phenomena, such as the emergence of a Mott insulator, superconductivity or the pseudogap phase of high-temperature superconductors. In semiconductors, a conduction-band electron attracts a valence-band hole (electronic vacancy) to create a bound pair, known as an exciton, which is yet another quasiparticle. Two excitons may also bind together to give molecules, often referred to as biexcitons, and even polyexcitons may exist. In indirect-gap semiconductors such as germanium or silicon, a thermodynamic phase transition may produce electron-hole droplets whose diameter can approach the micrometre range. In direct-gap semiconductors such as gallium arsenide, the exciton lifetime is too short for such a thermodynamic process. Instead, different quasiparticle configurations are stabilized dominantly by many-body interactions, not by thermalization. The resulting non-equilibrium quantum kinetics is so complicated that stable aggregates containing three or more Coulomb-correlated electron-hole pairs remain mostly unexplored. Here we study such complex aggregates and identify a new stable configuration of charged particles that we call a quantum droplet. This configuration exists in a plasma and exhibits quantization owing to its small size. It is charge neutral and contains a small number of particles with a pair-correlation function that is characteristic of a liquid. We present experimental and theoretical evidence for the existence of quantum droplets in an electron-hole plasma created in a gallium arsenide quantum well by ultrashort optical pulses.

Laparoscopic extralevator abdominoperineal excision of the rectum: short-term outcomes of a prospective case series.

BACKGROUND: Laparoscopic approaches for the resection of low rectal cancer and the extralevator technique for abdominoperineal excision are both becoming increasingly popular. There are little published data regarding the combined application of these techniques to the resection of low rectal tumours. The aim of this study was to assess the feasibility of such an approach and to appraise short-term outcomes in a consecutive series of patients undergoing laparoscopic extralevator abdominoperineal excision (ELAPE). METHODS: Consecutive patients undergoing laparoscopic ELAPE at our institution between 2008 and 2011 were identified from a prospectively maintained database. The abdominal phase of the operation was performed laparoscopically, and following extralevator resection, the perineum was reconstructed using a biologic mesh. All patients were enrolled in an enhanced recovery programme. RESULTS: Of 166 patients undergoing radical resection of rectal cancer at our institution between 2008 and 2011, 28 underwent laparoscopic ELAPE. Median age was 70 years, median body mass index was 27.5 kg/m(2), and 71% were male. The conversion rate to laparotomy was 18%. Three patients (10.8%) had circumferential resection margins <1 mm; no intraoperative tumour perforation occurred. The median length of stay was 7 days, with a 30-day readmission rate of 21% and no 30-day mortality. Post-operative perineal wound complications occurred in 25%. At median 38-month follow-up (range 23-66 months), overall survival was 75%, disease-free survival was 71%, and there were three local recurrences (11%). CONCLUSIONS: Laparoscopic extralevator abdominoperineal excision can be safely performed without compromising short-term outcomes.

The addition of gemtuzumab ozogamicin to low-dose Ara-C improves remission rate but does not significantly prolong survival in older patients with acute myeloid leukaemia: results from the LRF AML14 and NCRI AML16 pick-a-winner comparison.

The treatment of older patients with acute myeloid leukaemia, who are not considered suitable for conventional intensive therapy, is unsatisfactory. Low-dose Ara-C(LDAC) has been established as superior to best supportive care, but only benefits the few patients who enter complete remission. Alternative or additional treatments are required to improve the situation. This randomised trial compared the addition of the immunoconjugate, gemtuzumab ozogamicin (GO), at a dose of 5 mg on day 1 of each course of LDAC, with the intention of improving the remission rate and consequently survival. Between June 2004 and June 2010, 495 patients entered the randomisation. The addition of GO significantly improved the remission rate (30% vs 17%; odds ratio(OR) 0.48 (0.32-0.73); P=0.006), but not the 12 month overall survival (25% vs 27%). The reason for the induction benefit failing to improve OS was two-fold: survival of patients in the LDAC arm who did not enter remission and survival after relapse were both superior in the LDAC arm. Although the addition of GO to LDAC doubled the remission rate it did not improve overall survival. Maintaining remission in older patients remains elusive.

Assessing pig body language: agreement and consistency between pig farmers, veterinarians, and animal activists.

This study investigates the interobserver and intraobserver reliability of qualitative behavior assessments (QBA) of individual pigs by 3 observer groups selected for their diverging backgrounds, experience, and views of pigs. Qualitative behavior assessment is a "whole animal" assessment approach that characterizes the demeanor of an animal as an expressive body language, using descriptors such as relaxed, anxious, or content. This paper addresses the concern that use of such descriptors in animal science may be prone to distortion by observer-related bias. Using a free-choice profiling methodology, 12 pig farmers, 10 large animal veterinarians, and 10 animal protectionists were instructed to describe and score the behavioral expressions of 10 individual pigs (sus scrofa) in 2 repeat sets of 10 video clips, showing these pigs in interaction with a human female. They were also asked to fill in a questionnaire gauging their experiences with and views on pigs. Pig scores were analyzed with generalized procrustes analysis and effect of treatment on these scores with ANOVA. Questionnaire scores were analyzed with a χ(2) test or ANOVA. Observers achieved consensus both within and among observer groups (P < 0.001), identifying 2 main dimensions of pig expression (dim1: playful/confident-cautious/timid; dim2: aggressive/nervous-relaxed/bored), on which pig scores for different observer groups were highly correlated (pearson r > 0.90). The 3 groups also repeated their assessments of individual pigs with high precision (r > 0.85). Animal protectionists used a wider quantitative range in scoring individual pigs on dimension 2 than the other groups (P < 0.001); however, this difference did not distort the strong overall consistency of characterizations by observers of individual pigs. Questionnaire results indicated observer groups to differ in various ways, such as daily and lifetime contact with pigs (P < 0.001), some aspects of affection and empathy for pigs (P < 0.05), and confidence in the validity of personal QBA descriptors (P < 0.02). The main finding of this study is that despite such differences in background and outlook, the 3 observer groups showed high interobserver and intraobserver reliability in their characterizations of pig body language. This supports the empirical nature of QBA in context of the wider anthropomorphism debate.

Low-dose filgrastim significantly enhances neutrophil recovery following autologous peripheral-blood stem-cell transplantation in patients with lymphoproliferative disorders: evidence for clinical and economic benefit.

PURPOSE: To assess the clinical and economic benefit of low-dose (50 microg/m2) filgrastim after peripheral blood stem-cell transplantation (PBSCT) in a randomized, placebo-controlled double-blinded study. PATIENTS AND METHODS: Thirty-eight patients with lymphoproliferative disorders were randomized to receive low-dose filgrastim (19 patients) or placebo (19 patients) beginning on the first day after stem-cell reinfusion and continuing until absolute neutrophil count (ANC) was greater than 0.5 x 10(9)/L. All patients received greater than 2.5 x 10(6) CD34+ cells/kg, which was mobilized with chemotherapy and filgrastim 300 microg from the fifth day. An economic analysis was performed based on the outcome in the two groups. RESULTS: Neutrophil engraftment was significantly more rapid in patients who received filgrastim with a median number of days until ANC was greater that 0.5 x 10(9)/L of 10 (9 to 13) versus 14 (9 to 19; P < .0001). The time to reach an ANC greater than 1 x 109/L was 12 (9 to 14) versus 16 days (10 to 25; P < .0001). The total number of patients who required intravenous antibiotic therapy was lower in the filgrastim-treated group (68%) compared with the placebo group (89%); also, the median number of days with fever and the duration of antibiotic therapy were shorter, although these differences did not reach statistical significance. However, although only three of 19 (16%) patients who received filgrastim required amphotericin, 11 of 19 (58%) who received placebo did require it, and amphotericin usage was significantly less in the filgrastim group (P = .029). Finally, in-patient stay was significantly shortened in those who received filgrastim from 16 (13 to 23) to 13 days (11 to 18; P = .0003). CONCLUSION: Low-dose filgrastim significantly reduces neutrophil engraftment time post-PBSCT and also reduces in-patient stay and costs, which makes it economically viable for patients who are undergoing high-dose chemotherapy.

Bone marrow transplantation: current situation, complications and prevention.

The number of patients undergoing BMT is rising steadily. The increase is due to a broadening of the indications for transplantation and an increase in the donor pool. There has been a progressive improvement in outcome particularly due to a fall in transplant-related mortality. Methotrexate and cyclosporin are the mainstay of graft versus host disease (GVHD) prophylaxis, but acute GVHD remains a major problem in the unrelated donor recipient. Infections remain an important cause of death and emphasise the crucial role of antimicrobial prophylaxis; death from Gram-negative sepsis has been significantly reduced by the use of prophylactic antibiotics. Fungal infections carry a high mortality, especially in allogenic transplant recipients. Fluconazole is used to protect patients in the neutropenic period and beyond in higher risk individuals. Viral infections, which may occur late, are emerging as a significant cause of morbidity and mortality in the allogeneic, particularly unrelated transplantation setting. A long term susceptibility to encapsulated bacteria suggests delayed immune reconstitution; revaccination policies are standard in most units. The longer term effects of transplantation are increasingly important with improving survival and include chronic GVHD, endocrine, cardiorespiratory and other systemic abnormalities. The increased risk of secondary malignancies is also of concern.

Biological features of leukaemic cells associated with autonomous growth and reduced survival in acute myeloblastic leukaemia.

The blast cells from up to 70% of patients with acute myeloblastic leukaemia exhibit a variable degree of autonomous growth in vitro, which is related to the production of autocrine growth factors. It has recently been established that patients with autonomous blast cell growth have both a lower remission rate and a higher relapse rate, compared to otherwise comparable patients whose blasts exhibit non-autonomous in vitro growth. In a group of 50 patients the actuarial disease-free survival for the autonomous growth group was 11% at 5 years compared to greater than 50% for the non-autonomous growth group. This data suggests that AML blasts with autocrine growth characteristics may be resistant to cytotoxic drug therapy. Here we present further data demonstrating that AML blasts with autonomous growth are relatively resistant to the induction of programmed cell death (apoptosis) and that this is related to the autocrine production of GM-CSF. Also AML blasts with autonomous growths have aberrant expression of genes associated with resistance to apoptosis induced by cytotoxic drugs. These include high expression of the bcl-2 oncoprotein and abnormalities of expression of the p53 tumour suppressor gene. Furthermore bcl-2 expression was found to be unregulated by both exogenous and autocrine GM-CSF suggesting that the documented negative prognostic effect of autonomous growth on treatment outcome in AML, is in part due to the regulatory effect of autocrine GM-CSF on bcl-2 expression, thus protecting cells from apoptosis induced by cytotoxic drug therapy.

Differential toxicity of alpha-keto hydroxypyridine iron chelators and desferrioxamine to human haemopoietic precursors in vitro.

Compliance with iron chelation therapy improves life expectancy in transfusion-dependent haematological disorders. However, failure of compliance with parenteral desferrioxamine (DF) therapy and the expense incurred makes this drug unavailable for most patients in the developing world. We have been evaluating the orally active iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1) in both preclinical and clinical trials. Five patients have developed reversible agranulocytosis during treatment with this agent. We have now studied the effects of L1, other alpha-ketohydroxypyridines and DF on bone marrow myeloid progenitors using the CFU-GM system. The results show that L1 is less toxic than DF to normal bone marrow myeloid progenitors (ID50:130 mumol/l versus 7.9 mumol/l). The L1 ID50 is within the previously reported range of peak plasma values (80-450 mumol/l). When saturating concentrations of iron were added to the cultures, the mean toxicity of all the chelators was significantly decreased over the range of doses tested, e.g. L1 ID50, 567 mumol/l; DF ID50, > 1000 mumol/l. The toxicity of L1 in vitro was similar for marrows from 3 normal donors and for the recovery marrow from a patient with thalassaemia major who had experienced agranulocytosis. Further studies are required to elucidate the mechanisms of L1-induced agranulocytosis.

Autonomous growth of blast cells is associated with reduced survival in acute myeloblastic leukemia.

We have previously classified the in vitro growth characteristics of clonogenic blasts from patients with acute myeloblastic leukemia (AML) according to their capacity to proliferate autonomously in a blast cell colony assay. Here we have analyzed whether the presence of in vitro autonomous growth characteristics has any clinical relevance in AML. We have studied 50 patients (age 2 to 64 years), all of whom were treated with combination chemotherapy, excluding patients with a history of antecedent myelodysplasia. Leukemic cells from 34 of 50 patients (68%) exhibited either partial or totally autonomous growth in a blast cell colony assay. Cells from the remaining patients exhibited nonautonomous growth and were either totally dependent on exogenous growth factor (n = 8) or failed to proliferate at all in the culture system used (n = 8). All 50 patients were treated by intensive chemotherapy and 69% achieved complete remission (CR). Patients whose blasts exhibited autonomous growth in vitro had a significantly lower CR rate (57%) compared with the 16 patients with nonautonomous growth (94%, P = .02). White blood cell count was the only other significant factor (P = .03), but in multivariate analysis growth characteristics remains the most important predictor of CR. Actuarial relapse risk is 80% and 42% at 5 years for autonomous and nonautonomous groups respectively (P = .1). Overall disease-free survival is 21.8% and is higher in the nonautonomous growth group at 54.2% compared with 11.3% at 5 years (P = .0015) in the autonomous growth characteristics was found to be the single most important indicator of CR and disease-free survival. Our data suggests that the suppression of autocrine growth factor production may be of value in the treatment of AML.

Effective prevention of acute GVHD following allogeneic BMT with low leukaemic relapse using methotrexate and therapeutically monitored levels of cyclosporin A.

Although the combination of cyclosporin A (CYA) and methotrexate has been reported to reduce the incidence of acute GVHD in patients undergoing allogeneic BMT for leukaemia, it has been associated with a higher risk of leukaemic relapse. Since 1987 we have used the combination of CYA and methotrexate for GVHD prophylaxis in 24 patients undergoing allogeneic BMT for leukaemia or myelodysplasia. Over the first 50 days post-transplantation, CYA dosage was adjusted to keep within a therapeutic range of 95-205 ng/ml. This resulted in a 60% reduction in CYA dosage by day 50 post-transplant compared to the original Seattle protocol. Despite the low dosage of CYA administered, the incidence of acute GVHD was only 25% with no patient having greater than grade I GVHD. There have been no leukaemic relapses in low risk patients. The results indicate that decreasing CYA dosage does not increase the incidence of GVHD but may reduce the risk of leukaemic relapse following allogeneic BMT.

Failure of purged autologous bone marrow transplantation in high risk acute lymphoblastic leukaemia in first complete remission.

Patients in first remission of acute lymphoblastic leukaemia (ALL) considered to be at high risk of relapse were offered autologous bone marrow transplantation (ABMT) using purged marrow as a therapeutic alternative to cranial irradiation and maintenance chemotherapy. Twenty-seven bone marrows taken in remission, were purged using monoclonal antibodies (anti CD7 for T lineage and anti CD10 and/or anti CD19 for B lineage leukaemias) plus rabbit complement. Retrospective analysis of 19 purged marrows by immunophenotyping or immunoglobulin gene rearrangement studies demonstrated no evidence of disease. Engraftment was seen in 26 of the patients. No correlation was found between the numbers of infused nucleated cells or colony forming units-granulocyte-macrophage (CFU-GM) and subsequent engraftment kinetics. The actuarial disease-free survival (DFS) is 32% at 7 years (median follow-up 3.4 years). There were two transplant related deaths (actuarial risk 8%); the main cause of treatment failure has been disease recurrence with an overall actuarial risk of 67%; 76% for T-ALL (five of nine), 62% for common ALL (five of 10), two of five pre B and none of three patients with B-ALL. In these 27 high risk patients in vitro purging of remission marrow as part of ABMT appears not to improve patient outcome, although confirmation of this would require a randomized trial.

Granisetron, a selective 5-HT3 receptor antagonist, for the prevention of radiation induced emesis during total body irradiation.

The antiemetic efficacy of granisetron was tested in an open trial in patients undergoing highly emetogenic treatment by single fraction total body irradiation. Thirty-two consecutive patients were entered. Results were both patient- and observer-rated. Following a single intravenous dose of granisetron 18 patients (56.3%) experienced total protection and a further 13 (40.6%) had major antiemetic protection with four of these patients experiencing nausea only. One patient experienced an anaphylactic reaction on infusion of monoclonal antibody-treated donor marrow 5 h after administration of the trial drug and vomited on multiple occasions. The reaction was associated with hypotension. A further patient experienced transient hypotension secondary to septicaemia 8 h after receiving granisetron. Three patients required a second dose. Headache was the most frequent side-effect occurring in three patients, but in to of these patients the test drug was not thought to be implicated. In conclusion granisetron is a highly effective agent in controlling radiation induced emesis with a favourable toxicity profile.

Long-term indwelling silastic central venous catheters: clinical audit leading to improved surgical technique.

A retrospective audit of the surgical insertion and clinical outcome of silastic venous catheters on our Haematology Unit was performed for the period 1985 to 1988. Twenty-three (58%) of the 40 lines had complications, and analysis showed that many were due to problems related to the surgical technique used. This altered our clinical practice, and over a 12 month period (January 1989 to January 1990) 26 central venous catheters have been placed in 24 patients by a dedicated surgical team using a standardized, altered technique. This has been to place all catheters via the right internal jugular vein and to confirm line position by on-table radiographic screening. A significant improvement in results is presented.