Prodrugs for antibody- and gene-directed enzyme prodrug therapies (ADEPT and GDEPT)

Antibody- and gene-directed enzyme prodrug therapy are two-step targeting strategies designed to improve the selectivity of antitumour agents. The approaches are based on the activation of specially designed prodrugs by antibody-enzyme conjugates targeted to tumour-associated antigens (ADEPT) or by enzymes expressed by exogenous genes in tumour cells (GDEPT). Herein the design, synthesis, physico-chemical and biological properties, kinetics and clinical trials of the prodrugs and the enzymes carboxypeptidase G2 and nitroreductase are reviewed for ADEPT and GDEPT.

Prosocial action in very early childhood

We tested a model of prosocial development, which predicted that prosocial action might decline, not increase, throughout childhood, becoming increasingly selective, individual, gender-related, and linked to emotional dysregulation. Sixty-six focal children at 18, 24, or 30 months of age were observed at home with familiar peers and then again 6 months later. Episodes of peer interaction were analysed for instances of sharing. The predicted decline in sharing with age was qualified by cohort differences and many associations with gender. Most children shared less as they grew older, but the oldest girls slightly increased their rate of sharing over time. As peer relationships developed, girls were more likely to share with other girls; boys were more likely to show reciprocity in sharing. Individual differences in sharing were moderately stable over time and linked to another form of prosocial action, sensitivity to the peer's distress. As predicted, children who shared at higher rates were rated more negatively by their mothers. The positive relationship between prosocial action and mothers' ratings of negative personality traits was especially strong for boys.

Enhancement of antibody-directed enzyme prodrug therapy in colorectal xenografts by an antivascular agent

The irregular nature of solid tumor vasculature produces a heterogeneous distribution of antibody-targeted therapies within the tumor mass, which frequently results in reduced therapeutic efficacy. We have, therefore, combined two complementary therapies: Antibody-directed Enzyme Prodrug Therapy (ADEPT), which targets tumor cells, and an agent that selectively destroys tumor vasculature. A single i.p. dose (27.5 mg/kg) of the drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA), given to nude mice bearing the LS174T colorectal xenograft, destroyed all but a peripheral rim of tumor cells, without enhancing survival. The ADEPT system, in which a pretargeted enzyme activates a prodrug, consisted of the F(ab')2 fragment of anti-carcinoembryonic antigen antibody A5B7 conjugated to the bacterial enzyme carboxypeptidase G2 and the prodrug 4-[(2-chloroethyl)(2-mesyloxyethyl)amino]benzoyl-L-glutamic acid, which was given i.p. in three doses of 500 mg/kg at 72, 84, and 96 h post-conjugate administration (25 units of carboxypeptidase G2). The antibody-enzyme conjugate could be selectively retained at approximately twice the control levels by administration of the antivascular agent at the time of optimal conjugate localization within the tumor (20 h post-conjugate administration), as demonstrated by gamma counting, phosphor plate image analysis, and active enzyme measurement. This resulted in significantly enhanced tumor growth inhibition in groups of six mice, compared to conventional ADEPT therapy, with no concomitant increase in systemic toxicity. In a separate experiment, aimed at trapping the prodrug within the tumor, a 16-fold increase over control values was produced (means, 44.8 versus 2.8 microg/g tumor) when DMXAA was given 4 h prior to 4-[(2-chloroethyl)(2-mesyloxyethyl)amino]benzoyl-L-glutamic acid. The therapeutic window was small, with no significant enhancement of prodrug retention when DMXAA was given at either earlier or later time points. This correlated with the time of vascular shut-down induced by the antivascular agent. We are currently investigating whether it is more advantageous to trap increased levels of conjugate or prodrug within the tumor for maximal enhancement of conventional ADEPT. These studies demonstrate that combined use of antibody-directed and antivascular therapies can significantly benefit the therapeutic outcome of either strategy alone.

Oral corticosteroids in patients admitted to hospital with exacerbations of chronic obstructive pulmonary disease: a prospective randomised controlled trial

BACKGROUND

The role of oral corticosteroids in treating patients with exacerbations of chronic obstructive pulmonary disease (COPD) remains contentious. We assessed in a prospective, randomised, double-blind, placebo-controlled trial the effects of oral corticosteroid therapy in patients with exacerbations of COPD requiring hospital admission.

METHODS

We recruited patients with non-acidotic exacerbations of COPD who were randomly assigned oral prednisolone 30 mg once daily (n=29) or identical placebo (n=27) for 14 days, in addition to standard treatment with nebulised bronchodilators, antibiotics, and oxygen. We did spirometry and recorded symptom scores daily in inpatients. Time to discharge and withdrawals were noted in each group. We recalled patients at 6 weeks to repeat spirometry and collect data on subsequent exacerbations and treatment. Hospital stay was analysed by intention to treat and forced expiratory volume in 1 s (FEV1) according to protocol.

FINDINGS

FEV1 after bronchodilation increased more rapidly and to a greater extent in the corticosteroid-treated group: percentage predicted FEV1 after bronchodilation rose from 25.7% (95% CI 21.0-30.4) to 32.2% (27.3-27.1) in the placebo group (p<0.0001) compared with 28.2% (23.5-32.9) to 41.5% (35.8-47.2) in the corticosteroid-treated group (p<0.0001). Up to day 5 of hospital stay, FEV1 after bronchodilation increased by 90 mL daily (50.8-129.2) and by 30 mL daily (10.4-49.6) in the placebo group (p=0.039). Hospital stays were shorter in the corticosteroid-treated group. Groups did not differ at 6-week follow-up.

INTERPRETATION

These data provide evidence to support the current practice of prescribing low-dose oral corticosteroids to all patients with non-acidotic exacerbations of COPD requiring hospital admission.

Behavioural management in nursing and residential homes: a randomised controlled trial

BACKGROUND

As more and more elderly people are being cared for in residential and nursing homes, how best can their psychiatric needs be met? We report on evaluation of a behavioural intervention by an old-age psychiatry hospital outreach team.

METHODS

This randomised controlled trial of a training and education intervention over 6 months was done in south Manchester, UK. 12 matched nursing and residential homes were randomised to the control or intervention group and within each, the staff selected 10 residents whose behavioural problems made them difficult to care for. Care staff in the intervention homes attended seminars from the hospital outreach team and received weekly visits from a psychiatric nurse to assist in developing care planning skills. The main outcome measures were cognitive impairment and depression, behavioural disturbance, and functional ability, assessed by the geriatric mental state schedule, Crichton Royal behaviour rating scale, and Barthel index, respectively.

FINDINGS

Residents in the intervention group had significantly improved scores for depression (before-and-after change difference -0.5 [95% CI -0.8 to -0.1]) and for cognitive impairment (-0.7 [-1.1 to -0.2]) but not for behaviour rating or Barthel index.

INTERPRETATION

Elderly residents can benefit from improved quality of care achieved by training from a hospital outreach team.

Oral corticosteroid trials in the management of stable chronic obstructive pulmonary disease

Although recent guidelines for managing chronic obstructive pulmonary disease (COPD) recommend a trial of oral corticosteroids in the initial assessment, its prognostic value remains unclear. We prospectively studied 127 adults (64% men) with stable COPD (FEV1/FVC < 60%) over 1 year. At entry, we measured lung volumes, gas transfer factor, respiratory symptoms (by questionnaire), and peripheral blood eosinophil count. Skin-prick testing was done, and spirometry after nebulized 5 mg salbutamol and, after 2 weeks, oral prednisolone. Physician A gave all patients inhaled beclomethasone dipropionate (800 mcg/day), whereas physician B prescribed this only to those with a positive oral corticosteroid trial. At 1 year, spirometry and respiratory questionnaire were repeated, with an estimate of overall symptom severity on a visual analogue scale. Follow-up data were available in 104 (82%) patients. Of these, 32 (31%) were unresponsive to salbutamol and prednisolone; 48 (46%) were responsive to beta agonists but not to corticosteroids, and 24 (23%) responded to corticosteroids and salbutamol. Patients in all groups were comparable, except that the prednisolone responders had a higher mean eosinophil count (p < 0.001) and more were ex-smokers (p < 0.001). Only the response to oral prednisolone correlated with the change in prebronchodilator FEV1 over 1 year. Oral prednisolone responders had higher FEV1 at 1 year (p < 0.02) and significantly lower symptom scores (p < 0.02). In COPD, corticosteroid trials contribute information additional to that gained from nebulized bronchodilator reversibility testing. Patients with a positive response to a corticosteroid trial are more likely to have improved symptomatically and spirometrically at 1 year.

Seasonal and spatial changes in blowfly production from small and large carcasses at Durham in lowland northeast England

Colonization by blowflies (Diptera: Calliphoridae) of mouse carcasses exposed in open agricultural land near Durham (54 45'N) changed from early spring monopolization by Calliphora vicina R.-D. to a summer pattern of multiple species exploitation by this species together with Lucilia caesar L., L. illustris Mg., L. silvarum Mg., L. sericata Mg. and L. richardsi Collin. In a garden at the edge of Durham, mouse carcasses were dominated by C. vicina from spring to autumn. Difference in mouse colonization between the agricultural and garden sites seemed to reflect differences in the blowfly species present, as measured by baited trap catches at the sites. In sets of C. vicina reared from mice under conditions of competition for larval food, it was found that resulting females were significantly larger than males, size being measured as mean wing length. Blowfly production from three sheep carcasses exposed successively at the agricultural site was dominated by C. vomitoria L. and L. caesar, but also produced other Lucilia species in small numbers, including L. sericata. These L. sericata females from sheep that had died from causes other than myiasis included full-sized specimens, in contrast to those produced from mouse carcasses that were all undersized individuals. As L. sericata females trapped on sheep pastures are predominantly full-sized, this suggests that large carcasses may, in part, be a source of the L. sericata population that attacks sheep as a myiasis agent. The nature of large carcasses as possible sources of L. sericata in lowland Britain is discussed.

Spinal root and plexus hypertrophy in chronic inflammatory demyelinating polyneuropathy

MRI was performed on the spinal roots, brachial and lumbar plexuses of 14 patients with chronic inflammatory demyelinating polyneuropathy (CIDP). Hypertrophy of cervical roots and brachial plexus was demonstrated in eight cases, six of whom also had hypertrophy of the lumbar plexus. Of 11 patients who received gadolinium, five of six cases with hypertrophy and one of five without hypertrophy demonstrated enhancement. All patients with hypertrophy had a relapsing-remitting course and a significantly longer disease duration. Gross onion-bulb formations were seen in a biopsy of nerve from the brachial plexus in one case with clinically evident nodular hypertrophy. We conclude that spinal root and plexus hypertrophy may be seen on MRI, particularly in cases of CIDP of long duration, and gadolinium enhancement may be present in active disease.

Cooling and freezing damage platelet membrane integrity

Cytoskeletal rearrangements and a membrane lipid phase transition (liquid crystalline to gel) occur in platelets on cooling from 23 to 4 degrees C. A consequence of these structural alterations is irreversible cellular damage. We investigated whether platelet membrane integrity could be preserved by (a) previously studied combinations of a calcium chelator (EGTA) and microfilament stabilizer (cytochalasin B) with apparent benefit in protecting platelets from cooling injury or (b) agents of known benefit in protecting membranes and proteins from freezing injury. Platelet function and activation before and after freezing or cooling were measured by agglutination with ristocetin, aggregation with thrombin or ADP, platelet-induced clot retraction (PICR), and expression of P-selectin. Platelets were loaded with 10 nM fluorescein diacetate. After freezing or cooling, the preparations were centrifuged and the supernatant was measured for fluorescein. For cooling experiments, fresh platelets were chilled at 4 degrees C for 1 to 21 days with or without the combination of 80 microM EGTA/AM and 2 microM cytochalasin B (EGTA/AM-CytoB) and then warmed rapidly at 37 degrees C. For freezing experiments, 5% dimethyl sulfoxide (Me2SO) or 5 mM glycerol were added to fresh platelets. The preparations were then frozen at -1 degrees C/min to -70 degrees C and then thawed rapidly at 37 degrees C. Platelet membrane integrity, as measured by supernatant levels of fluorescein, correlated inversely with platelet function. Chilling platelets at 4 degrees C with EGTA/AM-CytoB showed a gradual loss of membrane integrity, with maximum loss reached on day 7. The loss of membrane integrity preceded complete loss of function as demonstrated by PICR. In contrast, platelets chilled without these agents had complete loss of membrane integrity and function after 1 day of storage. Freezing platelets in Me2SO resulted in far less release of fluorescein than did freezing with or without other cryoprotectants (P < 0.001). This result correlated with enhanced function as demonstrated by PICR and supports earlier observations that Me2SO protects platelet membranes from freezing injury. Release of fluorescein into the surrounding medium reflected loss of membrane integrity and function in both cooled and frozen platelets. Membrane cytoskeletal rearrangements are linked to membrane changes during storage. These results may be generally applicable to the study of platelet storage.

Effects of eyelid scrubbing on the lid margin

PURPOSE

To compare the effects of eyelid scrubbing with an eyelid cleansing solution (ECS) to eyelid scrubbing with ECS and the addition of antibacterial or anti-inflammatory pharmaceuticals on the clinical appearance, microbial status, tissue histology, and the inflammatory cell profile of the normal eyelid margin.

METHODS

Eyelid scrubbing was performed twice daily using ECS; ECS with the antibacterial sulfacetamide (ECS+); and ECS with sulfacetamide and prednisolone acetate (ECS++) over a 21 day period on three groups of 16 rabbits with clinically normal eyelids.

RESULTS

Significant hyperemia of the margin occurred in all three groups over the 3 week period; however, the degree of hyperemia was less with ECS+ (P<0.05) and ECS++ (P<0.05). Chemosis, tearing, mucus discharge, and the microbial status were not significantly different than controls. There were no marked histologic differences in the tissues, except for increased red blood cell packing in the small vessels near the lid margins in scrubbed eyelids, consistent with hyperemia. The inflammatory cell profile showed minimal changes that were not statistically significant in any of the three groups, except that >50% of mast cells showed evidence of degranulation.

CONCLUSIONS

Use of ECS with an antibiotic, or an antibiotic and steroid solution, resulted in less inflammation than scrubbing with ECS alone.

Inequalities in mortality and illness in Trent NHS Region

BACKGROUND

The Department of Health is encouraging health authorities to improve health status by tackling health inequalities. We defined ward level spatial health variations in Trent National Health Service Region, England, investigated urban and rural inequalities, and examined the relationship with deprivation, to identify the extent of small area health inequalities and to establish whether a quantifiable difference exists between urban and rural health as affected by deprivation.

METHOD

A small area ecological study design was adopted and ward level (n=591) standardized ratios were calculated (population aged <75, n=3,900,000) for specific causes of death and limiting long-term illness. A classification was devised to assess ward health inequalities according to an urban-rural dimension. Deprivation was measured using the Townsend Index and the relationship with mortality and illness was analysed using Pearson product moment correlation.

RESULTS

Wide variations in mortality and illness were evident at ward level, being widest for accident mortality (standardized mortality range 0-508). Stroke mortality accounted for the largest proportion of wards with standardized mortality ratios over 125 (36.2 per cent). Relative deprivation correlated strongly with limiting long-term illness (r=0.82) and all-cause mortality (r=0.68) across Trent, and in both urban and rural environments.

CONCLUSION

The study set health inequalities within a regional context for Trent as an initiative to coincide with the Government's proposed health strategy for the next few years. Wide health inequalities were evident in Trent and the association between deprivation and health was of a similar magnitude in urban and rural wards. This small area approach allows health authorities access to ward level information in order to inform key debate on tackling health inequalities and distributing resources in relation to need.

Endogenous mouse interleukin-10 is up-regulated by exogenously administered recombinant human interleukin-10, but does not contribute to the efficacy of the human protein in mouse models of endotoxemia

In murine models of experimental endotoxemia, inflammatory cytokines as well as antiinflammatory interleukin-10 (IL-10) appear in the circulation after the injection of lipopolysaccharide (LPS). There is considerable experimental evidence to suggest that the major function of endogenously produced IL-10 is to down-regulate inflammatory cytokine production. Indeed, the protective effects of exogenously administered IL-10 against murine endotoxin lethality have been shown to correlate with its ability to inhibit the LPS-induced production of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). While mouse IL-10 (mIL-10) has been used in the majority of studies in murine endotoxemia, we have found the human homolog to be equally effective in suppressing inflammatory cytokine production and in protecting mice from endotoxin lethality. However, we have recently observed that the LPS-induced endogenous IL-10 response is enhanced when mice are treated with recombinant human IL-10 (rhuIL-10). The upregulation of endogenous IL-10 by exogenously administered rhuIL-10 is particularly evident in mice that are primed with Corynebacterium partum (Proprionibacterium acnes). In the present study, we have examined the potential contributions of the increased circulating levels of mouse IL-10 to the inhibitory effects seen with rhuIL-10 on inflammatory cytokine production and endotoxin lethality. We show that pretreatment with a neutralizing anti-mouse IL-10 monoclonal antibody (mAb) has no effect on the ability of rhuIL-10 to suppress an LPS-induced inflammatory cytokine response in these mice. In contrast, the suppressive effects of the human protein on inflammatory cytokine responses are blocked completely by pretreating the animals with an anti-huIL-10 mAb. These data show that despite the up-regulated endogenous IL-10 response, it is the exogenously administered rhuIL-10 that is directly responsible for the suppressed inflammatory cytokine responses that are observed when the human protein is given to endotoxemic mice.

The relationship of prorenin values to microvascular complications in patients with insulin-dependent diabetes mellitus

We have performed a cross-sectional analysis of the relationship between prorenin values and the microvascular complications of diabetes in a well controlled population of insulin-dependent diabetes mellitus (IDDM) subjects. One hundred and thirty-nine subjects (75 men, 64 women, age 44 +/- 17 years; duration of diabetes 19 +/- 15 years), formed the study group. Sixty-seven subjects (48.2%) had no complications, 55 (39.6%) had retinopathy alone, and 17 (12.2%) had retinopathy and albuminuria. Patients with no complications had lower prorenin values than those with microvascular complications (p < 0.001), whilst patients with both albuminuria and retinopathy had higher values than those with retinopathy alone (p < 0.05). Retinopathy was associated with duration of diabetes (p < 0.0001), diastolic blood pressure (p < 0.02) and albuminuria (p < 0.0001) while albuminuria was associated with prorenin (p < 0.02), serum triglyceride (p < 0.01) and retinopathy (p < 0.001). Patients with albuminuria were 5.5 times more likely to have raised prorenin values (>80 ng/mL/h) than those with normal albumin excretion [95% confidence interval (CI): 1.48-20.12] and those with retinopathy alone were 2.5 times as likely (95% CI: 1.19-5.15). Eighty patients with IDDM (40 males, 40 females; age: 47 +/- 17 years; duration of diabetes: 20 +/- 15 years), had retinal photography performed to determine the association between the severity of retinopathy and prorenin values. Retinopathy was more severe in patients with retinopathy and albuminuria than in those with retinopathy alone (p < 0.002). When the prorenin values of patients with more marked retinopathy (eye grade greater than 3) were compared, prorenin values of those with retinopathy and albuminuria were greater than those of patients with retinopathy alone [269 (139-1406) versus 91 (41-273) ng/mL/h: geometric mean (range); p < 0.05]. Furthermore, when patients without albuminuria were considered, there was no significant difference between the prorenin levels of patients with more severe retinopathy (eye grade >3) when compared to patients with lesser degrees of retinopathy [91 (41-273) versus 69 (23-375). In patients with microvascular complications, prorenin values were independently predicted by albuminuria (p < 0.0001) and diastolic blood pressure (p < 0.02) but not the severity of retinopathy. In conclusion, prorenin values are significantly associated with the presence of microvascular complications in patients with IDDM. The association with albuminuria may be stronger than the association with retinopathy.

Self-immolative nitrogen mustard prodrugs for suicide gene therapy

Four new potential self-immolative prodrugs derived from phenol and aniline nitrogen mustards, four model compounds derived from their corresponding fluoroethyl analogues and two new self-immolative linkers were designed and synthesized for use in the suicide gene therapy termed GDEPT (gene-directed enzyme prodrug therapy). The self-immolative prodrugs were designed to be activated by the enzyme carboxypeptidase G2 (CPG2) releasing an active drug by a 1, 6-elimination mechanism via an unstable intermediate. Thus, N-[(4-¿[4-(bis¿2-chloroethyl¿amino)phenoxycarbonyloxy]methyl¿pheny l)c arbamoyl]-L-glutamic acid (23), N-[(4-¿[4-(bis¿2-chloroethyl¿amino)phenoxycarbonyloxy]methyl¿pheno xy) carbonyl]-L-glutamic acid (30), N-[(4-¿[N-(4-¿bis[2-chloroethyl]amino¿phenyl)carbamoyloxy]methyl¿+ ++phen oxy)carbonyl]-L-glutamic acid (37), and N-[(4-¿[N-(4-¿bis[2-chloroethyl]amino¿phenyl)carbamoyloxy]methyl¿+ ++phen yl)carbamoyl]-L-glutamic acid (40) were synthesized. They are bifunctional alkylating agents in which the activating effects of the phenolic hydroxyl or amino functions are masked through an oxycarbonyl or a carbamoyl bond to a benzylic spacer which is itself linked to a glutamic acid by an oxycarbonyl or a carbamoyl bond. The corresponding fluoroethyl compounds 25, 32, 42, and 44 were also synthesized. The rationale was to obtain model compounds with greatly reduced alkylating abilities that would be much less reactive with nucleophiles compared to the corresponding chloroethyl derivatives. This enabled studies of these model compounds as substrates for CPG2, without incurring the rapid and complicated decomposition pathways of the chloroethyl derivatives. The prodrugs were designed to be activated to their corresponding phenol and aniline nitrogen mustard drugs by CPG2 for use in GDEPT. The synthesis of the analogous novel parent drugs (21b, 51) is also described. A colorectal cell line was engineered to express CPG2 tethered to the outer cell surface. The phenylenediamine compounds were found to behave as prodrugs, yielding IC50 prodrug/IC50 drug ratios between 20- and 33-fold (for 37 and 40) and differentials of 12-14-fold between CPG2-expressing and control LacZ-expressing clones. The drugs released are up to 70-fold more potent than 4-[(2-chloroethyl)(2-mesyloxyethyl)amino]benzoic acid that results from the prodrug 4-[(2-chloroethyl)(2-mesyloxyethyl)amino]benzoyl-L-glutamic acid (CMDA) which has been used previously for GDEPT. These data demonstrate the viability of this strategy and indicate that self-immolative prodrugs can be synthesized to release potent mustard drugs selectively by cells expressing CPG2 tethered to the cell surface in GDEPT.

Resource costing for multinational neurologic clinical trials: methods and results

We present the results of a multinational resource costing study for a prospective economic evaluation of a new medical technology for treatment of subarachnoid hemorrhage within a clinical trial. The study describes a framework for the collection and analysis of international resource cost data that can contribute to a consistent and accurate intercountry estimation of cost. Of the 15 countries that participated in the clinical trial, we collected cost information in the following seven: Australia, France, Germany, the UK, Italy, Spain, and Sweden. The collection of cost data in these countries was structured through the use of worksheets to provide accurate and efficient cost reporting. We converted total average costs to average variable costs and then aggregated the data to develop study unit costs. When unit costs were unavailable, we developed an index table, based on a market-basket approach, to estimate unit costs. To estimate the cost of a given procedure, the market-basket estimation process required that cost information be available for at least one country. When cost information was unavailable in all countries for a given procedure, we estimated costs using a method based on physician-work and practice-expense resource-based relative value units. Finally, we converted study unit costs to a common currency using purchasing power parity measures. Through this costing exercise we developed a set of unit costs for patient services and per diem hospital services. We conclude by discussing the implications of our costing exercise and suggest guidelines to facilitate more effective multinational costing exercises.

Delayed egg production and a possible group effect in the blowfly Calliphora vicina

Protein-fed Calliphora vicina, F1 offspring of wild flies in two cages with lower and higher fly densities showed variable delay in starting oocyte vitellogenesis at ambient semi-natural temperatures in warm July-August weather in 1996 and 1997 at Durham in northern England (54 degrees 45' N). The high-density flies in 1996 showed no delay, in that the thermal sum (degree-days) experienced was 133, comparable to 18 degrees C constant, assuming the lower threshold for egg maturation to be 5 degrees C. Low-density cages and flies in a large outdoor cage (2 m3) in both years showed delays in production of first eggs of 34 days (thermal sum 293 degree-days) in 1996 and 32 days (396 degree-days) in 1997, and longer delays for other individuals. Delays in egg production at low densities relative to high densities seem to be a group effect of unknown mechanism.

Conduction block in vasculitic neuropathy

Vasculitis involving peripheral nerves usually presents as an acute asymmetrical axonal neuropathy. We report a 67-year-old man with a symmetrical subacute neuropathy in which nerve conduction studies showed prominent conduction block, a finding indicative of demyelination. Sural nerve biopsy showed a vasculitic neuropathy with invasion of blood vessel walls by inflammatory cells and a mixture of nerve fiber loss and demyelination. The demyelination in this case was presumably a consequence of subinfarctive nerve ischemia.

Methodological and statistical issues of quality of life (QoL) and economic evaluation in cancer clinical trials: report of a workshop

In recent years, quality of life (QoL) and economic evaluations have become increasingly important as additional outcome measures in cancer clinical trials. However, both fields of research are relatively new and in need of finding solutions to a substantial number of specific methodological problems. This paper reports on the proceedings of a symposium aimed at summarising and discussing some of the most contentious methodological and statistical issues in QoL and economic evaluations. In addition, possible solutions are indicated and the most pertinent areas of research are identified. Issues specific to QoL evaluations that are addressed include clinically meaningful changes in QoL scores; how to analyse QoL data and to handle missing and censored data and integration of length of life and QoL outcomes. Issues specific to economic evaluations are the advantages and disadvantages of various outcome measures; statistical methods to analyse economic data and choice of decision criteria and analytical perspective. How to perform QoL and economic evaluations in large and simple trials and whether the gap between QoL and utility measures can be bridged are also discussed.

The role of descending basal ganglia connections to the brain stem in parkinsonian akinesia

Akinesia is the most disabling symptom of Parkinson's disease. The neural mechanisms underlying it probably involve the descending projections of the basal ganglia to the brain stem as it improves after a pallidotomy or subthalamic nucleotomy but not after a thalamotomy. We describe the effects of lesioning the pedunculopontine nucleus in the normal primate in generating an akinetic syndrome. The possible clinical implications of this study are discussed.

Safety of plasmapheresis in the treatment of neurological disease

BACKGROUND

Plasmapheresis is used as a treatment modality in several neurological disorders. Adverse reactions relating to vascular access, replacement fluid and anticoagulant use have been reported.

AIMS

To establish the incidence of complications of therapeutic plasmapheresis in the treatment of neurological diseases.

METHODS

A retrospective study was performed, in which case records of patients undergoing plasmapheresis for neurological indications between 1 April 1992 and 1 September 1996 were reviewed for fatalities and adverse reactions related to vascular access, transmission of Hepatitis B or C or Human Immunodeficiency Virus (HIV), fluid imbalance, allergic or febrile reactions, haematological complications, machine failure and citrate toxicity.

RESULTS

In the study period, 1283 plasmapheresis procedures were performed on 73 patients with neurological disease. There were no fatalities, no cases of Hepatitis B or C or HIV transmission, no allergic or febrile reactions, thrombosis, bleeding diathesis or severe citrate toxicity. Infections related to venous access occurred in 0.5 per cent of procedures with septicaemia in 0.2 per cent of procedures (4.1% of patients). Less serious complications included hypotension in 1.2 per cent of procedures (11% of patients) and citrate toxicity manifesting as nausea, vomiting, cramping or paraesthesia in 1.2 per cent of procedures. Machine failure occurred in 0.2 per cent of procedures.

CONCLUSIONS

Plasmapheresis is a safe procedure when performed for neurological indications by experienced personnel in a large pheresis unit. The most frequent adverse event is infection of the venous access site.