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Biomedical subjects

A Ng

Publications and source records attributed to A Ng.

At least 19 recordsLinked to original sources
PubMed2007

Anaplastic large cell lymphoma of bone--is it a bad tumor?

A teenage boy presented with a CD30-positive anaplastic large cell lymphoma (ALCL) affecting his scapula and was successfully treated with chemotherapy. His clinical features and outcome were compared with other cases described in the literature. A further review of 11 ALCL cases with bony involvement treated in the UK since 1990, including two with primary bone disease, did not suggest an unfavorable treatment outcome. This finding will need to be confirmed by further study on a larger patient cohort with primary bone ALCL.

Activin Receptors, Type II↗
PubMed2007

Anaesthetic outcome and predictive risk factors in children with mediastinal tumours.

PURPOSE: The aims were to identify and test the significance of specific factors associated with risks for anaesthesia in children with mediastinal tumours. PATIENTS AND METHOD: Clinical information was retrospectively collected from the records of 63 children presented with mediastinal tumour (1964-2002) in a regional Paediatric Oncology centre and correlated with the type and outcome of anaesthesia, using non-parametric analyses. RESULTS: Thirteen patients had local anaesthesia or sedation for diagnostic procedures and none developed any complication. Fifty children received general anaesthesia (GA) for diagnostic investigations or tumour resection. Two patients were excluded from the analysis because of treatment prior to GA. Problems with intubation, ventilation and cardiovascular collapse were encountered in 7 of 48 (15%) patients and this resulted in tracheostomy in one patient and death in 2 other cases. When compared with the 41 uncomplicated cases, the presence of at least 3 respiratory symptoms/signs, tracheal and vascular compression, and infection significantly increased the risk of GA. Of these, tracheal compression remained the strongest predictive factor. CONCLUSIONS: Decision to postpone GA should be considered if all these risk factors (tracheal compression, vascular compression, the presence of at least three respiratory symptoms/signs) are present in the same patient.

Adolescent↗
PubMed2006

Broadband dielectric function of nonequilibrium warm dense gold.

We report on the first single-state measurement of the broadband (450-800 nm) dielectric function of gold isochorically heated by a femtosecond laser pulse to energy densities of 10(6) - 10(7) J/kg. A Drude and an interband component are clearly seen in the imaginary part of the dielectric function. The Drude component increases with energy density while the interband component shows both enhancement and redshift. This is in strong disagreement with predictions of a recent calculation of dielectric function based on limited Brillouin zone sampling.

Journal Article↗
PubMed2006

Optical properties in nonequilibrium phase transitions.

An open question about the dynamical behavior of materials is how phase transition occurs in highly nonequilibrium systems. One important class of study is the excitation of a solid by an ultrafast, intense laser. The preferential heating of electrons by the laser field gives rise to initial states dominated by hot electrons in a cold lattice. Using a femtosecond laser pump-probe approach, we have followed the temporal evolution of the optical properties of such a system. The results show interesting correlation to nonthermal melting and lattice disordering processes. They also reveal a liquid-plasma transition when the lattice energy density reaches a critical value.

Journal Article↗
PubMed2006

Genotoxicity of etoposide: greater susceptibility of MLL than other target genes.

The ability of topoisomerase 2 inhibitors to induce DNA breakage is well recognized. Previous studies, however, have concentrated on the effects on individual genes. The effects of etoposide on the MLL, RUNX1, and MLLT3 genes were simultaneously studied in the same hemopoietic cell population. We found MLL to be more susceptible to etoposide-induced cleavage than RUNX1 and MLLT3, with maximum cleavage at a lower drug concentration. A higher level of MLL than other gene cleavage was also detected after cellular exposure to all drug concentrations. Greater susceptibility to topoisomerase 2 inhibitor-induced cleavage may explain the more frequent involvement of MLL in treatment-related leukemogenesis.

Core Binding Factor Alpha 2 Subunit↗
PubMed2005

A prospective study of septicaemia on a paediatric oncology unit: a three-year experience at The Royal Liverpool Children's Hospital, Alder Hey, UK.

Septicaemia in neutropaenic patients is predominantly due to gut translocation [endogenous septicaemia] and contamination of the central venous catheter by microorganisms not carried by the patient [exogenous septicaemia]. To control both types of infection, a protocol was implemented based on pre 1990's parenteral and enteral antimicrobials together with strict hygiene. Surveillance cultures of throat/rectum were taken to distinguish exogenous from endogenous septicaemia and enteral non-absorbable antibiotics are administered as part of selective decontamination of the digestive tract (SDD). This protocol was evaluated in a 14-bedded paediatric oncology unit over a period of 3 years. 313 Septicaemia episodes were recorded in 131 children. 28.4% of the septicaemias were caused by microorganisms associated with the unit, equivalent to 0.82 episodes per 100 patient days. Low-level pathogens such as coagulase-negative staphylococci caused more than 70% of infections. Amongst the potential pathogens, Pseudomonas species (7.8%) and Staphylococcus aureus (5.5%) were predominant. Antibiotic resistance was rare with no superinfections or outbreaks. Four patients (3%) died, two due to Candida species and two due to Pseudomonas aeruginosa. We believe that the addition of enteral non-absorbable antibiotics to systemic antibiotics maintained a low level of resistance and mortality but a randomised controlled trial is indicated to confirm these observations.

Adolescent↗
PubMed2005

Effects of topoisomerase 2 inhibitors on the MLL gene in children receiving chemotherapy: a prospective study.

The molecular effects of etoposide in haemopoietic cells suggest that mixed lineage leukaemia (MLL) abnormalities can be biomarkers of patient susceptibility to the genotoxic effects of topoisomerase 2 (topo 2) inhibitors. We have prospectively studied treatment-related MLL cleavage and rearrangement in serial samples from 71 children receiving chemotherapy, using Southern blot analysis and panhandle PCR. The results were related to patient demographics, treatment details and outcome. MLL cleavage was identified in six bone marrow samples from five patients 2-10 months after the start of therapy. There was no obvious relationship between the degree of MLL cleavage and cumulative dose or schedule of topo 2 inhibitors. Three children with low percentage (23-30%) cleavage remained well and two were still receiving treatment at study completion. One child with two consecutively positive samples and higher level of MLL cleavage (45-48%) died from treatment-related toxicities and relapsed leukaemia. A patient with haemophagocytic lymphohistiocytosis developed the highest level of MLL cleavage (50%) at 3 months and a treatment-related leukaemia with MLL rearrangement 6 months after the start of treatment. It would appear that some patients are inherently more susceptible to the genotoxic effect of topo 2 inhibitors. The degree and persistence of MLL cleavage may identify patients at risk.

Adolescent↗
PubMed2004

Coexistence of treatment-related MLL cleavage and rearrangement in a child with haemophagocytic lymphohistiocytosis.

Treatment-related acute myeloid leukaemia (t-AML) is a serious complication of topoisomerase 2 inhibitor therapy and is characterised by the presence of mixed lineage leukaemia (MLL) rearrangement. By molecular tracking, we were able to show that MLL cleavage preceded gene rearrangement by 3 months and before the clinical diagnosis of t-AML in a patient with haemophagocytic lymphohistiocytosis. This is the first report on the sequential detection of the two biomarkers in treatment-related leukaemogenesis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2004

Early analgesic effects of parecoxib versus ketorolac following laparoscopic sterilization: a randomized controlled trial.

BACKGROUND: The aim of this prospective double blind randomized controlled trial was to compare the effects of ketorolac and parecoxib on early postoperative pain. METHOD: We studied 36 ASA I/II patients who received a standardized general anaesthetic for laparoscopic sterilization. Patients were allocated randomly to receive either parecoxib 40 mg i.v. or ketorolac 30 mg i.v., at induction. After surgery, patients were assessed on awakening and then at 1, 2, and 3 h. Abdominal pain at rest and on inspiration, in addition to nausea and sedation were assessed on a 100 mm visual analogue scale. RESULTS: Of 36 patients, one was excluded from analysis. In the remaining patients, pain scores at rest and on inspiration were significantly lower in patients given ketorolac compared with those given parecoxib. This difference was attributable to the higher pain scores on awakening and at 1 h postoperatively in the parecoxib group compared with the ketorolac group. Despite this initial difference, there was no significant difference between the two groups in the number of patients receiving rescue analgesia. The median (interquartile range) time to consumption of rescue cocodamol of 60 (46-74) min in the parecoxib group was not significantly shorter than that of 100 (70-130) min in the ketorolac group. The amount of cyclizine given, nausea and sedation did not differ significantly between the groups. CONCLUSION: We found that parecoxib 40 mg i.v. given at induction of anaesthesia was less effective than or ketorolac 30 mg i.v., in the first hour after laparoscopic sterilization.

Adult↗
PubMed2004

Single-state measurement of electrical conductivity of warm dense gold.

We report on a single-state measurement of electrical conductivity of warm dense gold in the solid to plasma transition regime. This is achieved using the idealized slab plasma approach of isochoric heating of ultrathin samples by a femtosecond laser, coupled with femtosecond probe measurements of reflectivity and transmission. The experiment also reveals the time scale associated with the disassembly of laser heated solid.

Journal Article↗
PubMed2004

Is continuous spinal analgesia via an epidural catheter appropriate after accidental subarachnoid administration of 15 mL of bupivacaine 0.1% containing fentanyl 2 micrograms/mL?

We report a case of accidental insertion of an epidural catheter into the subarachnoid space and accidental administration of 15 mL of bupivacaine 0.1% with fentanyl 2 micrograms/mL, in the sitting position, during labour. Within 5 min, the patient was unable to move her lower limbs. Although the upper level of the sensory block using ethyl chloride was found to be T5, there was no cardiovascular depression. The catheter was left in situ and used for continuous spinal analgesia. Further administration of the bupivacaine-fentanyl solution was not required until after 315 min. The patient was given five further 2- to 3-mL top-up doses of bupivacaine-fentanyl at intervals of 105 to 145 min. After 16 h, caesarean section was performed for failure to progress in the first stage of labour. This was conducted under spinal anaesthesia using 2 mL of hyperbaric bupivacaine 0.5% with fentanyl 20 micrograms. A healthy baby was delivered with Apgar scores of 10 and 10, at 1 and 5 min, respectively. There was no postdural puncture headache or any neurological complications.

Adult↗
PubMed2004

Is intraperitoneal levobupivacaine with epinephrine useful for analgesia following laparoscopic cholecystectomy? A randomized controlled trial.

BACKGROUND AND OBJECTIVE: A randomized controlled trial of patients undergoing laparoscopic cholecystectomy. To evaluate whether the instillation of levobupivacaine, with epinephrine, intraperitoneally, reduces morphine consumption; further, to consider the degree of abdominal and shoulder pain in the presence of local anaesthetic at the site of surgical incision. METHODS: Patients received a standardized procedure and were allocated randomly to receive either (a) 2.5 mg mL(-1) levobupivacaine 30 mL, with epinephrine 5 microg mL(-1), or (b) normal saline 30 mL, with epinephrine 5 microg mL(-1), to the bed of the gall bladder and above the liver, immediately before wound closure. RESULTS: Median (interquartile range) total abdominal pain during inspiration in the levobupivacaine group was significantly (P = 0.041) lower (71 (21-129) mm) than that in the placebo group (123 (71-179) mm). However, there was no significant difference between the two groups with respect to total abdominal pain at rest, right shoulder pain or the consumption of rescue morphine and rescue dihydrocodeine. There were no differences between the two groups with respect to the administration of cyclizine, total nausea and total sedation scores. In addition, the number of episodes of vomiting was not significantly different. CONCLUSIONS: Intraperitoneal administration of levobupivacaine with epinephrine is associated with modest analgesia following laparoscopic cholecystectomy.

Adult↗
PubMed2004

Partial CD8+ T-cell depletion of allogeneic peripheral blood stem cell transplantation is insufficient to prevent graft-versus-host disease.

Prior studies suggest that depletion of CD8+ T cells from donor bone marrow or donor lymphocyte infusions can reduce graft-versus-host disease (GVHD) without compromising graft-versus-leukemia. We explored CD8 depletion in patients undergoing matched related donor (MRD, n=25) and unrelated donor (URD, n=16) peripheral blood stem cell transplantation following myeloablative conditioning with cyclophosphamide (60 mg/kg/day i.v. x 2) and total body irradiation (200 cGy x 7 fractions). Ex vivo incubation of mobilized donor peripheral blood cells with anti-CD8 antibody coated high-density microparticles removed 99% of CD8+ cells. The median number of CD8+ cells infused was 3.9 x 10(5) cells/kg (2.2 x 10(5) in MRD, and 8.1 x 10(5) in URD patients). Post transplant immune suppression included tacrolimus in the MRD cohort, and tacrolimus plus mini-methotrexate (5 mg/m2 days +1, 3, 6, 11) in the URD cohort. All 41 patients engrafted. Grade 2-4 acute GVHD incidence was 61% (44% MRD, 88% URD). Chronic GVHD incidence was 50% (48% MRD, 55% URD). Relapse incidence was 4.9%. Estimated event-free and overall survival rates were 65 and 63%, respectively, at 1 year and 56 and 57%, respectively, at 2 years. There was no correlation between CD8+ number and GVHD or survival. A 2-log depletion of CD8+ cells from PBSC is insufficient to prevent GVHD.

Adult↗
PubMed2003

Nonequilibrium and non-steady-state evolution of a shock state.

Using numerical simulations, we study the evolution of silicon in the passage of a constant-pressure shock wave launched from an adjacent pusher. We examine also its optical characteristics of reflectivity and emission. Our finding points to the study of shocked interfaces as a novel means to explore nonequilibrium, non-steady-state behaviors of shock states and an alternative approach to assess electron-ion equilibration rate in a shock wave. It also reveals important structures in such a shock wave in contrast to its usual notion as a propagating discontinuity. This offers some possibilities for reconciling the different findings on the compressibility of deuterium.

Journal Article↗
PubMed2003

Outcome after autologous and allogeneic stem cell transplantation for patients with multiple myeloma: impact of graft-versus-myeloma effect.

A total of 228 patients with multiple myeloma (MM), 166 patients receiving autologous transplantation (124 PBSC and 38 BM) and 66 patients receiving T-cell-depleted allogeneic transplantation were analyzed to compare overall survival (OS), progression-free survival (PFS) and risk of relapse. Patients receiving autologous transplantation had a significantly improved OS (P=0.006) and PFS (P=0.002) at 2 years with OS and PFS for autologous transplant 74% and 48%, respectively, compared with 51% and 28% for allogeneic transplantation. By 4 years after transplantation, outcome was similar with OS and PFS for autologous transplantation 41% and 23%, respectively, compared with 39% and 18% for allogeneic transplantation. The 4-year cumulative incidence of nonrelapse mortality was significantly higher in patients receiving allogeneic transplantation (24% vs 13%) (P=0.004). Relapse was the principle cause of treatment failure for both groups; however, there was a significantly reduced risk of relapse associated with allogeneic transplantation at 4 years: 46% for allograft vs 56% for autograft (P=0.02). Despite a lower risk of relapse after allogeneic transplantation, autologous transplantation is associated with improved OS and PFS compared with allogeneic transplantation in patients with MM. Strategies focused on reducing nonrelapse mortality in allogeneic transplantation may translate into an improved outcome for patients receiving allogeneic transplantation.

Adult↗