Haemostatic resuscitation in practice: a descriptive analysis of blood products administered during Operation HERRICK, Afghanistan

INTRODUCTION

Life-threatening haemorrhage is the leading cause of potentially survivable injury in battlefield casualties. During Operation HERRICK (Afghanistan), mortality rates improved year on year due to a number of advances in trauma care, including haemostatic resuscitation. Blood transfusion practice has not previously been reported in detail during this period.

METHODS

A retrospective analysis of blood transfusion at the UK role 3 medical treatment facility (MTF) at Camp Bastion between March 2006 and September 2014 was performed. Data were extracted from two sources: the UK Joint Theatre Trauma Registry (JTTR) and the newly established Deployed Blood Transfusion Database (DBTD).

RESULTS

3840 casualties were transfused 72 138 units of blood and blood products. 2709 adult casualties (71%) were fully linked with JTTR data and were transfused a total of 59 842 units. Casualties received between 1 unit and 264 units of blood product with a median of 13 units per patient. Casualties wounded by explosion required almost twice the volume of blood product transfusion as those wounded by small arms fire or in a motor vehicle collision (18 units, 9 units, and 10 units, respectively). More than half of blood products were transfused within the first 2 hours following arrival at the MTF. There was a trend towards balanced resuscitation with more equal ratios of blood and blood products being used over time.

CONCLUSION

This study has defined the epidemiology of blood transfusion practice during Operation HERRICK. The DBTD is the largest combined trauma database of its kind. It will ensure that lessons learnt during this period are defined and not forgotten; it should also allow further research questions to be answered in this important area of resuscitation practice.

A versatile microtomography system to study in situ the failure and fragmentation in geomaterials

This article describes a microtomography experimental platform enabling in situ micro-mechanical study of failure and fragmentation in geomaterials. The system is based on an original high-pressure triaxial flow cell, which is fully integrated into a custom built microtomography scanner equipped with a laboratory x-ray source. The design of the high-precision mechanical apparatus was informed by the concurrent development of advanced tomographic reconstruction methods based on helical scanning and of algorithms correcting for hardware inaccuracies. This experimental system produces very high-quality 3D images of microstructural changes occurring in rocks undergoing mechanical failure and substantial fragmentation. We present the results of two experiments as case studies to demonstrate the capabilities and versatility of this instrumental platform. These experiments tackle various questions related to the onset of rock failure, the hydromechanical coupling and relaxation mechanisms in fractured rocks, or the fragmentation process in geomaterials such as copper ores.

Tackling the burden of the hepatitis C virus in the UK: characterizing and assessing the clinical and economic consequences

OBJECTIVES

The hepatitis C virus (HCV) remains a significant public health issue. This study aimed to quantify the clinical and economic burden of chronic hepatitis C in the UK, stratified by disease severity, age and awareness of infection, with concurrent assessment of the impact of implementing a treatment prioritization approach.

STUDY DESIGN AND METHODS

A previously published back projection, natural history and cost-effectiveness HCV model was adapted to a UK setting to estimate the disease burden of chronic hepatitis C and end-stage liver disease (ESLD) between 1980 and 2035. A published meta-regression analysis informed disease progression, and UK-specific data informed other model inputs.

RESULTS

At 2015, prevalence of chronic hepatitis C is estimated to be 241,487 with 22.20%, 33.72%, 17.22%, 16.67% and 10.19% of patients in METAVIR stages F0, F1, F2, F3 and F4, respectively, but is estimated to fall to 193,999 by 2035. ESLD incidence is predicted to peak in 2031. Assuming all patients are diagnosed and treatment is prioritized in F3 and F4 using highly efficacious direct-acting antiviral (DAA) regimens, a 69.85% reduction in ESLD incidence is predicted between 2015 and 2035, and the cumulative discounted medical expenditure associated with the lifetime management of incident ESLD events is estimated to be £1,202,827,444.

CONCLUSIONS

The prevalence of chronic hepatitis C is expected to fall in coming decades; however, the ongoing financial burden is expected to be high due to an increase in ESLD incidence. This study highlights the significant costs of managing ESLD that are likely to be incurred without the employment of effective treatment approaches.

Dehydrative thiolation of allenols: indium vs gold catalysis

Intermolecular additions of thiols to allenols via formal S(N)2' selectivity to produce functionalized dienes are described. Although this dehydrative reaction was initially developed using gold(I) catalysis, indium(III) proves to be a far superior catalyst in terms of selectivity and substrate scope.

In vivo RAF signal transduction as a potential biomarker for sorafenib efficacy in patients with neuroendocrine tumours

BACKGROUND

Targeted therapies elicit anticancer activity by exerting pharmacodynamic effects on specific molecular targets. Currently, there is limited use of pharmacodynamic assessment to guide drug administration in the routine oncology setting.

METHODS

We developed a phosphoshift (pShift) flow cytometry-based test that measures RAF signal transduction capacity in peripheral blood cells, and evaluated it in a phase II clinical trial of oral sorafenib plus low-dose cyclophosphamide in patients with advanced neuroendocrine tumours (NETs), in order to predict clinical course and/or guide individual dose-titration.

RESULTS

Twenty-two patients were enrolled. Median progression-free survival (PFS) was 3 months (95% CI 2-10.7), and one patient had a partial response. PFS was longer among five patients who demonstrated an increase in pShift after 7 days of sorafenib compared with those who did not (14.9 months vs 2.8 months; P=0.047). However, pShift did not add value to toxicity-based dose-titration.

CONCLUSION

The pharmacodynamic assessment of RAF transduction may identify selected patients with advanced NETs most likely to benefit from the combination of sorafenib plus cyclophosphamide. Further investigation of this test as a potential biomarker is warranted.

Raman Characterization of Nitrogen Doped Multiwalled Carbon Nanotubes

N-type multi-walled nanotubes were synthesized by nitrogen doping using pyridine and pyridine-melamine mixtures in chemical vapor deposition, and their donor states were verified by Scanning Tunneling Spectroscopy. Tunneling Electron Microscopy reveals small amounts of residual catalyst and Scanning Electron Microscopy show well aligned mats of the Nitrogen doped nanotubes. Nitrogen is present in the lattice of these MWNTs as pyridine structures and CNx structures. Raman scattering measurements were performed as a function of increasing growth temperature and the results compared to previously studied boron doped multiwalled nanotubes.

An assessment of the efficiency of the Glostavent ventilator

In parts of the world where supplies of oxygen and electricity are erratic, ventilating patients' lungs can be problematic. Should the electricity supply fail, gas driven ventilators have an advantage as they can continue functioning. However, many are extravagant in their requirement for the driving gas. The Glostavent ventilator was designed to minimise these requirements. We measured the duration of ventilation achieved by the Glostavent ventilator using an E-size oxygen cylinder at a range of minute volumes, and the inspired oxygen concentration achieved by recycling the driving gas. The period of mechanical ventilation from a single E-size cylinder ranged from 11 h 8 min (SD 4 min) with a minute volume of 7 l min(-1) to 18 h 15 min (SD 7 min) with a minute volume of 3 l min(-1). The mean fractional inspired oxygen concentration achieved by recycling the driving gas without further inspired oxygen supplementation was 0.33. We conclude that the Glostavent ventilator performs as efficiently and cost effectively as predicted.

Phase II trial of pharmacodynamically (PDally)-guided optimal biologic dose titration (OBDT) of sorafenib (S) in combination with metronomic cyclophosphamide (mC) in advanced neuroendocrine tumors (aNET)

3526

Background: There is a paucity of reliable PD assays for guiding individual OBDT. PD effects of kinase inhibitors have been previously measured in static tissues. We developed a dynamic flow-cytometric PD assay that quantitates RAF signal transduction capacity (STC) based on the differential MEK´s phosphor-status in stimulated vs. basal conditions (phosphor-shift [PS]) in PBMCs. In a pilot study of 7 patients (pt) with advanced solid tumors in a phase I trial (unpublished data) the % of PS inhibition (I) 7 days after starting S at 400 mg BID showed a 10-fold interpatient variation and correlation with TTP. PDGFR-B/VEGFR2 blockade plus mC showed synergistic effect in the RIP1-Tag2 mouse NET model (J Clin Oncol. 23:939) In this phase II trial of aNET a double antiagniogenic strategy is undertaken: PD-guided OBDT of S + mC. Methods: Eligibility criteria included: unresectable NET with documented PD within 6 months prior to entry; ECOG 0–2; unlimited prior therapy but S; octreotide allowed. Therapy: pt start run-in phase with S at 200mg bid + 50 mg QD fixed dose of mC. After 7 d they escalate to 400 mg BID of S regardless of RAF STC assay results. RAF STC and toxicity are then assessed Q14d, escalating S at 200 mg BID increments until any of the following is achieved: a) 90% RAF STC I; b) maximum S dose of 800 mg BID; or c) intolerable Gr 2 or G3+ toxicity. Once S dose is determined based on these criteria, cycle 1 begins. Design: Simon 2-stage optimal; P0 = 0.05 P1 = 0.2; α =0.05 β = 0.1. Results: Accrual: 10 pt M:F = 6:4, islet cell:carcinoid = 5:5, age median 56 (40–79), ECOG 0:1 = 5:5. S doses (mg BID) at cycle 1 were 200 (2 pt)/400 (5)/600 (2)/800 (1); corresponding cycle 1 day 1RAF STC I (%) were 5, 53/94, 100, 95, 16, 65/25, 41/71, respectively (R2 = 0.13 p = 0.72) Most frequent Gr 3 non-hematologic possibly related adverse events in 30 cycles: hand-foot (2 pt), hypertension, abdominal pain, diarrhea, vomiting, lipase, ileal perforation (1 each). Disease control rate (9 evaluable pt): 78% (95% CI: 52–100%) (1PR, 6 SD). Conclusions: This approach appears feasible/safe. Large interpatient S dose differences are needed to achieve RAF SCT I/toxicity balance. No S dose-RAF SCT I relation is shown. Disease control rate is promising.

No significant financial relationships to disclose.

Phase I study of intravenous decitabine in combination with oral vorinostat in patients with advanced solid tumors and non-Hodgkin's lymphomas (NHL)

3528

Background: Decitabine (D), a hypomethylating agent, and vorinostat (V), a histone deacetylase inhibitor, belong to two different classes of drugs with an epigenetic effect. The ideal dose scheduling of these drugs remains controversial. This phase I study aims to determine the recommended phase II dose (RPTD) of the combination, their toxicity profile, pharmacokinetic (PK) interaction and preliminary clinical activity. Methods: Patients (pts) with advanced solid tumors or relapsed/refractory NHL are eligible. Two different schedules of D and V are being evaluated: sequential administration of D followed by V and concurrent administration of D and V. Dose escalation of D and V on the sequential schedule is described in Table. Results: To date, 27 pts have been entered into dose levels 1, -1, 1a, 1b, -1b, -2b of the sequential schedule. Demographics: median age 61 (range 31–76), F:M = 13:14, ECOG 0:1:2 = 8:16:3, tumor types: 24 solid tumor and 3 NHL. Pts received a total of 77 cycles with a median of 2 cycles (range 1–8). Adverse events (AE) of grade 3 or higher of at least possible attribution to the study treatment were neutropenia (16 pts), thrombocytopenia (4), febrile neutropenia (2), fatigue (2), and 1 pt each for constipation, dehydration, nasal bleeding, elevated alanine aminotransferase, and hyponatremia. Dose limiting toxicities (DLT) consisted mainly of myelosuppression, constitutional and gastrointestinal symptoms occurred in 7/27 (26%) of pts so far. Disease stabilization for 4 or more cycles was observed in 7 out of 22 (31.8%) evaluable pts (two with breast and one each of thymus, colon, pancreatic, appendix and non-small cell lung cancers). Conclusions: The sequential combination of D and V seems to be tolerable after some adjustments in the doses and duration of drug administration. Prolonged disease stabilization has been observed in multiple tumor types. Accrual is ongoing and RPTD will likely be dose level -1b or -2b. ( Supported by NCI Grant No. U01CA132123.)

[Table: see text]

No significant financial relationships to disclose.

A phase I study of vorinostat (VOR) in combination with capecitabine (CAP) in patients (pts) with advanced solid tumors

3576

Background: VOR (suberoylanilide hydroxamic acid; SAHA) is a small molecule inhibitor of histone deacetylase (HDAC) that binds directly to the enzyme’s active site in the presence of a zinc ion. Aberrant HDAC activity has been implicated in a variety of cancers. The combination of 5-fluorouracil and VOR is synergistic in preclinical tumor models. Methods: This phase I study evaluated safety, tolerability, and the recommended phase II dose (RPTD) of VOR and CAP in pts with advanced solid tumors. VOR was administered orally daily while CAP was administered orally bid on days 1–14 of a 21 d cycle. Results: Three dose levels have been evaluated (VOR (mg/d)/CAP (mg/bid)): 300/750, 300/1,000 and 400/1,000. Twenty-three pts have been treated: 6M/17F, median age 59 (range 41–73), ECOG 0:1:2 = 9:13:1, prior therapy 1:2:3 or more = 3:7:13. Pts had colorectal cancer (n=6), nasopharyngeal (n=3) and various other tumors. A total of 104 cycles have been administered, with median = 2 (range 1–15). One dose limiting toxicity (DLT) (grade 3 diarrhea) occurred in 6 patients at dose level 1. No DLT were observed at dose level 2, and 2 DLTs (grade 3 fatigue and grade 3 nausea/vomiting) occurred at dose level 3. RPTD was determined to be VOR 300 mg/d and CAP 1,000 mg/bid. Most common toxicities of any grade and at least possibly attributable (n=22) are: thrombocytopenia (59% of pts), fatigue (55%), nausea (55%), vomiting (50%), hypoalbuminemia (45%), anemia (41%), diarrhea (41%), anorexia (41%), elevated creatinine (36%), lymphopenia (36%), hyponatremia (36%), and hyperglycemia (36%). Common grade 3 toxicities included: hand-foot syndrome (23% of pts), diarrhea (14%), fatigue (14%), and lymphopenia (14%). One pt died on study from ventricular fibrillation due to sotalol and hypocalcemia from pre-existing hypoparathyroidism. Five patients with various tumor types had PR (2 confirmed, 3 unconfirmed) (2 nasopharyngeal, 1 each of ovarian, endometrial and squamous cell carcinoma of head and neck). In addition, disease stabilization was seen in 12 patients. Conclusions: VOR and CAP are well tolerated, and this combination is active in several tumor types. Further evaluations of VOR and CAP are warranted.

No significant financial relationships to disclose.

Optical properties of vanadium oxide nanotubes

The optical properties of vanadium oxide nanotube dispersions have been characterized using visible and near infrared absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and nonlinear transmission of optical intensities in the visible and near infrared. Using transmission electron microscopy, optical properties have been correlated to the occurrence of two distinct nanoparticle morphologies: nanotubes and unrolled tubes or platelets. Raman spectroscopy indicates that color changes associated with tub unrolling can be attributed to V2O5 formation. The nanotube and platelet morphologies both show strong optical intensity limiting at 532 and 1064 nm. However, dependencies on repetition rate suggest that slightly different mechanisms dominate at the two wavelengths.

The multidisciplinary approach to mental health crisis management: an Australian example

Changes within the Australian health care system have led many people with mental health disorders to use emergency departments as the point of access to mental health services. Staff in emergency departments are not necessarily equipped to assess the needs of such clients. This paper briefly describes the development of a multidisciplinary mental health liaison team, within the emergency department of one hospital in Sydney, which was designed to assist both staff and clients. Available evidence suggests the implementation of the team has been a success, however, more research is required to confirm the effectiveness of this approach. Questions are raised about appropriate referral and follow-up for some clients. The study also found deficiencies in the method of routine data collection (Emergency Department Identification System), which makes formal auditing of the team and the services it provides a difficult task.

High-protein diets augment albuminuria in rats with Heymann nephritis by angiotensin II-dependent and -independent mechanisms

Urinary albumin excretion (U(alb)V) increases following dietary protein augmentation (DPA) in nephrotic humans and rats. Angiotensin-converting enzyme inhibitors (ACEI) blunt, but do not entirely prevent, increased U(alb)V at doses that reduce blood pressure and entirely block the pressor effect of exogenously administered angiotensin I (Ang-I), suggesting that angiotensin II (Ang-II) might not mediate the effect of DPA on U(alb)V. We determined the effect of losartan (Los), a specific Ang-II receptor antagonist, and compared its effect to that of enalapril (En), an ACEI, on DPA-induced increase in U(alb)V in rats with passive Heymann nephritis (HN). When Los was administered to HN rats for 48 h prior to DPA from 8.5 to 40% casein. U(alb)V increased in an identical fashion in treated and untreated rats, even though Los caused hypotension and prevented the pressor effect of infused Ang-II. Only on day 6 after DPA did U(alb)V decrease. We then measured the effect of duration of pretreatment with Los on Ang-II binding to isolated glomeruli. Maximal inhibition of Ang-II binding required treatment with Los for 6 days. We then pretreated HN rats with either En or Los for 6 days prior to DPA. In contrast to administration of Los for 2 days prior to DPA, pretreatment with either Los or En for 6 days entirely prevented any increase in U(alb)V. We then increased dietary NaCl from 0.2% to 2% (HS) to determine whether En or Los would modulate U(alb)V after DPA when Ang-II activity was suppressed. En reduced the DPA-mediated increase in U(alb)V regardless of dietary NaCl, while Los was effective only in when dietary NaCl was reduced (0.2%), suggesting that under these conditions ACEI reduces U(alb)V by a mechanism that is independent of inhibition of Ang-II and that high protein diets augment U(alb)V by both Ang-II-independent and Ang-II-dependent mechanisms.

Comorbidities and quality of life in patients with interferon-refractory chronic hepatitis C

OBJECTIVES

Patients with chronic hepatitis C (HCV) consistently report a reduction in multiple domains of health-related quality of life (HRQOL) that does not correlate with liver disease severity. This may in part be due to the use of insensitive HRQOL instruments or extrahepatic factors that independently influence HRQOL. We hypothesized that a past history of substance abuse or active medical and psychiatric comorbidities would correlate with HRQOL scores.

METHODS

In 107 patients who had failed previous interferon therapy, HRQOL was measured by using the modified SF-36, a disease-specific instrument, and the Health Utilities Index (HUI) Mark III, a generic instrument.

RESULTS

Multiple SF-36 subscale and summary scores as well as the HUI Mark III attributes of emotion and pain were significantly reduced in the study population compared with healthy controls (p < 0.001). Serum alanine aminotransferase and HCV RNA levels, HCV genotype, liver histology, and HCV risk factors as well as demographic variables did not correlate with modified SF-36 and HUI scores. In addition, a history of alcohol abuse or dependency and intravenous drug use or dependency, identified in 52 and 51% of participants, respectively, did not correlate with HRQOL scores. However, the presence of one or more active medical comorbidities, defined as a chronic medical condition requiring treatment and monitoring, was significantly associated with both the modified SF-36 scores and HUI attribute deficits (p < 0.001). In particular, painful medical comorbidities or depressed mood requiring treatment were significantly associated with modified SF-36 scores and with HUI attribute deficits and utility scores (p < 0.001).

CONCLUSIONS

Active medical and psychiatric comorbidities may account for some of the reduction and variability in HRQOL scores in patients with chronic HCV who have failed previous interferon therapy. Future studies that control for the presence of active comorbidities in large groups of treatment naive patients with varying severity of chronic HCV are needed to confirm these findings.

Systemic delivery of an adenoviral vector encoding canine factor VIII results in short-term phenotypic correction, inhibitor development, and biphasic liver toxicity in hemophilia A dogs

Canine hemophilia A closely mimics the human disease and has been used previously in the development of factor VIII (FVIII) protein replacement products. FVIII-deficient dogs were studied to evaluate an in vivo gene therapy approach using an E1/E2a/E3-deficient adenoviral vector encoding canine FVIII. Results demonstrated a high level of expression of the canine protein and complete phenotypic correction of the coagulation defect in all 4 treated animals. However, FVIII expression was short-term, lasting 5 to 10 days following vector infusion. All 4 dogs displayed a biphasic liver toxicity, a transient drop in platelets, and development of anticanine FVIII antibody. Canine FVIII inhibitor development was transient in 2 of the 4 treated animals. These data demonstrate that systemic delivery of attenuated adenoviral vectors resulted in liver toxicity and hematologic changes. Therefore, the development of further attenuated adenoviral vectors encoding canine FVIII will be required to improve vector safety and reduce the risk of immunologic sequelae, and may allow achievement of sustained phenotypic correction of canine hemophilia A.

Predictive value of plasma human chorionic gonadotrophin following assisted conception treatment

A total of 429 pregnancies after assisted conception treatment was analysed, using receiver operator characteristic curves. The best balance between sensitivity and specificity for predicting viable (single and multiple births) and non-viable (fetal heart positive abortions, ectopic and biochemical pregnancies) outcomes was human chorionic gonadotrophin (HCG) 50 IU/l on day 14 and 200 IU/l on day 21 after treatment. Utilizing these indices all pregnancies could be classified into one of four groups. In group A (day 14 HCG <50 IU/l and day 21 <200 IU/l), the probability of a birth was 0%, pregnancy loss 72% and ectopic pregnancy 28%. Conversely for group D (day 14 HCG >50 IU/l and day 21 >1000 IU/l), the likelihood of a birth was 90%, pregnancy loss 8% and ectopic pregnancy only 1%. Between groups A and D there was, as expected, a gradually shifting balance in favour of a reduction in ectopic (28, 13, 3, 1%) and biochemical pregnancies (70, 36, 33, 2%) and an increase in fetal heart positive pregnancy losses (2, 6, 13, 7%) and births (0, 44, 50, 90%). The majority of multiple pregnancies (98%) occurred in group D. Two accurately linked HCG measurements allowed a greater predictive accuracy of pregnancy outcome than could be obtained using either alone.

Donor variation in the growth properties and osteogenic potential of human marrow stromal cells

Human marrow stromal cells (MSCs) were isolated from posterior illiac crest marrow aspirates obtained from 17 healthy donors, ages 19-45 years, with no apparent physical disability. First passage hMSCs exhibited growth rates in vitro that varied up to 12-fold between donors. No correlation between growth rate and the age or gender of the donor was evident (P </= 0.05). When hMSCs were cultured without passage for eight days (subconfluent cultures) or 22 days (confluent cultures) in the absence of any osteogenic agonists, levels of alkaline phosphatase enzyme activity varied 40-fold and 10-fold, respectively, between donors. When exposed to osteo-inductive media, donor populations also showed dramatic differences in levels of bone-specific gene induction. Collectively, these data demonstrate that hMSC cultures are composed of a heterogeneous mixture of cells at various stages of differentiation and with distinct osteogenic potentials. Differences in both growth rate and ALP activity were evident in hMSC cultures established from multiple aspirates obtained over a six month period from the same donors. Therefore, it appears that cellular heterogeneity produced by the method of harvest is propagated within and among different donor populations during culture expansion in vitro.

Alternative pathway of complement is activated during in vitro ventricular assist

BACKGROUND

Although ventricular assist devices (VAD) have improved survival in selected patients, their use continues to be complicated by thromboembolism and end-organ failure. Complement activation may play a role in the pathogenesis of these complications. Previous studies have found that the complement common terminal pathway is activated during VAD circulation. C3a levels rise dramatically during VAD use. Because the C3a fragment is generated by either the alternative or classical pathway, the purpose of this study is to determine the relative importance of the respective pathways in complement activation during in vitro VAD circulation.

METHODS

Six in vitro VAD circuits were simulated for 3 days using 450 mL of human blood. Temperature, activated clotting time, pH, pCO2, pO2, Ca2+, and glucose were maintained at physiologic levels. Enzyme immunoassays were used to measure concentrations of fragment Bb to indicate alternative pathway activation and fragment C4d to indicate classical pathway activation.

RESULTS

Fragment Bb concentrations rise from 1.92 to 10.77 micrograms/mL during the first 6 hours of circulation. Thereafter, Bb levels plateau. C4d concentrations slowly rise from a baseline of 1.49 to 6.84 micrograms/mL in 72 hours.

CONCLUSIONS

These findings suggest that both the alternative and classical pathways of complement are activated during VAD circulation. Alternative pathway activation precedes classical pathway activation during in vitro VAD circulation and may be of greater clinical importance during clinical VAD circulation.

Phase II study of dexverapamil plus anthracycline in patients with metastatic breast cancer who have progressed on the same anthracycline regimen

The purpose of this study is to evaluate whether metastatic breast cancer that has progressed on an anthracycline-containing drug regimen will subsequently respond to that identical regimen if dexverapamil, a modulator of P-glycoprotein-mediated drug resistance, is given concomitantly. Eligible patients received 180 mg/m2 dexverapamil every 6 h for 15 doses with the anthracycline administered 30 min after the seventh dose. Blood for dexverapamil levels was drawn before and 30 min after this dose. When possible, biopsies were obtained to measure mdr-1 expression by reverse transcription-PCR and by image cytometry. Of the 21 patients entered onto the trial, 20 were evaluable for response. There were two partial responses (10%) that both lasted for 6 months, and two additional patients had stable disease. Seven patients had asymptomatic cardiotoxicity consisting of hypotension (24%), bradycardia (5%), or prolongation of the P-R interval (14%). Two patients developed acute congestive heart failure, one on dexverapamil and one 10 days after stopping it. Dexverapamil did not seem to increase anthracycline toxicity. The median trough dexverapamil plus norverapamil level on day 3 was 1110 ng/ml (range, 186-3385 ng/ml), and the median peak level was 2164 ng/ml (range, 964-8382 ng/ml). There was poor correlation between reverse transcription-PCR and image cytometry for the level of mdr-1 expression. Because dexverapamil has been shown to affect doxorubicin pharmacokinetics subsequent to the initiation of this trial, it cannot be concluded that the responses seen were necessarily due to P-glycoprotein inhibition. Additional studies are necessary to determine whether mdr-1 modulators can reverse clinical drug resistance in breast cancer patients. The intrinsic cardiotoxicity of dexverapamil makes it less suitable for such studies than several other available agents.

Irreversible dimerization/tetramerization and post-translational modifications inhibit proteolytic degradation of A beta peptides of Alzheimer's disease

Experimental evidence increasingly implicates the beta-amyloid peptide in the pathogenesis of Alzheimer's disease. Beta-amyloid filaments dramatically accumulate in the neuritic plaques and vascular deposits as the result of the brain's inability to clear these structures. In this paper, we demonstrate that in addition to the intrinsic stability of A beta N-42, the time dependent generation of irreversibly associated A beta dimers and tetramers incorporated into A beta filaments are themselves resistant to proteolytic degradation. The presence of post-translational modifications such as isomerization of aspartyls 1 and 7, cyclization of glutamyl 3 to pyroglutamyl and oxidation of methionyl 35, further contribute to the insolubility and stability of A beta. All these factors promote the accumulation of neurotoxic amyloid in the brains of patients with Alzheimer's disease, and should be considered in therapeutic strategies directed towards the dissociation of the brain's A beta filaments.

Realtime three-dimensional remote medical skills acquisition

Three-dimensional techniques are gaining widespread use in a number of disciplines, including medicine, where the visualization of depth information is not only useful but important. Both computer-generated 3-D imaging and 3-D video are set to become increasingly important tools for both diagnosis and teaching. In this paper we will present some of the work that we are currently undertaking using 3-D techniques for remote surgical skills acquisition. This work is based on the use of a small headset with twin miniature video cameras, video codecs, two different 3-D visualization systems and BT's ISDN telecommunications network.

Complications of obstetric epidural analgesia and anaesthesia: a prospective analysis of 10 995 cases

Although epidural anaesthesia and analgesia are widely used in obstetrics, there are no large contemporary prospective series detailing associated complications. Prospective data was collected on all obstetric epidural blocks performed for labour and delivery in a single institution between July 1989 and August 1994. A data entry sheet was compiled and entered onto a computer database. Confidence intervals for proportions were calculated using standard methods. Information from 10 995 epidural blocks was analysed. Epidural analgesia in labour was the primary indication in 7648, and anaesthesia for caesarean section in 3311. Minor complications included failed or abandoned insertion (incidence 0.5%), reinsertion of the epidural catheter (5%), and inadequate anaesthesia (1.7%) or analgesia (0.9%). Three percent were associated with venous puncture and 0.6% with accidental dural puncture. Maternal mortality was zero. Unexpectedly high blocks occurred on eight occasions (0.07%), two requiring intubation and ventilation. Three women (0.06%) experienced mild respiratory depression after postoperative epidural opioid. There was no major local anaesthetic toxicity or neurological deficit. The incidence of potentially life-threatening morbidity was thus 0.02% although in both cases outcome was good. The only persisting complication was neurological, an apparent epidural catheter-induced traumatic mononeuropathy.