A Gender-Bias-Mitigated, Data-Driven Precision Medicine System to Assist in the Selection of Biological Treatments of Grade 3 and 4 Knee Osteoarthritis: Development and Preliminary Validation of precisionKNEE

Objective To identify key variables predictive of patient responses to microfragmented adipose tissue (MFAT) treatment in knee osteoarthritis (KOA) and evaluate its potential to delay or mitigate the need for total knee replacement (TKR). Methods We utilised a dataset comprising 329 patients treated with MFAT for KOA, incorporating variables such as gender, age, BMI, arthritic aetiology, radiological grade, and Oxford Knee Scores (OKS) pre- and post-treatment. We employed random forest regressors for model training and testing, with gender bias mitigation and outlier detection to enhance prediction accuracy. Model performance was assessed through root mean squared error (RMSE) and mean absolute error (MAE), with further validation in a TKR-suitable patient subset. Results The model achieved a test RMSE of 6.72 and an MAE of 5.38, reflecting moderate predictive accuracy across the patient cohort. Stratification by gender revealed no statistically significant differences between actual and predicted OKS improvements (p-values: males = 0.93, females = 0.92). For the subset of patients suitable for TKR, the model presented an increased RMSE of 9.77 and MAE of 7.81, indicating reduced accuracy in this group. The decision tree analysis identified pre-operative OKS, radiological grade, and gender as significant predictors of post-treatment outcomes, with pre-operative OKS being the most critical determinant. Patients with lower pre-operative OKS showed varying responses based on radiological severity and gender, suggesting a nuanced interaction between these factors in determining treatment efficacy. Conclusion This study highlights the potential of MFAT as a non-surgical alternative for KOA treatment, emphasising the importance of personalised patient assessments. While promising, the predictive model warrants further refinement and validation with a larger, more diverse dataset to improve its utility in clinical decision-making for KOA management.

Experience of being chair and co-chair of the ECMC and reasons why you should be the NEXT

This article provides testimonials of the past and current chairs and co-chairs of the ECMC (@EarlyCareerERS) and a glimpse of the NEXT programme, along with participants' experiences. https://bit.ly/3LzvqKf.

Oral and maxillofacial injuries associated with e-scooter use at Broomfield Hospital: a cohort study of 24 months of data since e-scooter legalisation in the UK

Introduction Rental electronic scooters (e-scooters) were legalised in July 2020 in the UK for use on public roads. This has led to higher numbers of emergency department (ED) attendances for head and neck injuries managed by the oral and maxillofacial surgical (OMFS) department.Aim The aim of this research is to assess the increase in e-scooter injuries requiring OMFS input and analyse factors and management associated.Method Data were collected over a 24-month period. A total of 212 e-scooter-related ED presentations were recorded, with 34 patients requiring input from the OMFS department. For the patients referred to OMFS, numerical and categorical factors used independent T-tests and one-way Analysis of Variance tests, respectively, to determine statistical significance at the 5% confidence level (p <0.05).Results The mean age was 32.8 years (SD = 15.9) in a predominately male cohort (79.4%). Alcohol intoxication was observed in 55.8% of accidents. Injuries were most common on Saturdays (41.2%). Soft tissue injuries were present in 64.7% of patients, bony injuries in 38.2% of patients and dental injuries in 11.8% of patients. Imaging was required for 76.5% of patients. In total, 44% of patients required surgical treatment, 5.9% required major surgery and 38.2% required minor surgery.Conclusion This research supports the literature suggesting significant growth in e-scooter-related injuries and their associated burden of conditions managed by the OMFS department.

370 Pure Primary Small Cell Carcinoma of the Prostate: A Rare Entity

Introduction

We report a case of small cell carcinoma of the prostate (SCCP) which is a rare, high-grade malignant neoplasm accounting for 1% of all prostate cancers (CPa).

Case

Presentation

Conclusions

SCCP metastasizes early and therefore the clinical presentation is often in an advanced stage. It is noted that there is limited value of serum PSA for SCCP diagnosis. Instead, pathological examinations and MRI rectum are vital. In terms of treatment, chemotherapy provides relief of the clinical symptoms and its use is in in accordance with the 2016 National Comprehensive Cancer Network guidelines.

130 Improving Documentation of Bowel Movement on Geriatric Wards

Introduction

Constipation is a widely prevalent issue in older adults that may result in complications such as urinary retention, delirium and bowel obstruction. Previous studies have indicated that while stool charts are well completed by nursing staff, they are infrequently monitored by doctors. This project aimed to improve the documentation of bowel movement by doctors on ward rounds to 85%, by the end of a 3-month period.

Methods

Formulation of the project was achieved using group work and a fishbone diagram which focussed on how doctors can improve on documenting bowel movements. Baseline data were collected from inpatient notes on weekdays over a three-week period on a geriatric ward in Northern General Hospital, Sheffield. Interventions of posters and stickers of the poo emoji were placed on walls and in inpatient notes respectively as a reminder. Post-intervention data were collected on weekdays over two weeks, and then repeated a month later to assess for a sustained change.

Results

The data on bowel activity documentation were collected from 28 patients. The baseline data showed that bowel activity was monitored daily on the ward 56.25% of the time. There was a significant increase in documentation of 85.75% following the interventions. The sustainability study showed that bowel activity was documented on the ward 59.09% of the time.

Conclusions

This study shows how a strong effect on behavioural change can be accomplished through simple interventions such as stickers and posters. As most wards currently still use paper notes, this is a generalisable model that other wards can trial. However, this study also shows the difficulty in maintaining behavioural change over extended periods of time. Further PDSA cycles should examine the reasons behind the difficulty sustaining the change and implement new changes that aim to overcome them.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

The Analysis of Teaching of Medical Schools (AToMS) survey: an analysis of 47,258 timetabled teaching events in 25 UK medical schools relating to timing, duration, teaching formats, teaching content, and problem-based learning

BACKGROUND

What subjects UK medical schools teach, what ways they teach subjects, and how much they teach those subjects is unclear. Whether teaching differences matter is a separate, important question. This study provides a detailed picture of timetabled undergraduate teaching activity at 25 UK medical schools, particularly in relation to problem-based learning (PBL).

METHOD

The Analysis of Teaching of Medical Schools (AToMS) survey used detailed timetables provided by 25 schools with standard 5-year courses. Timetabled teaching events were coded in terms of course year, duration, teaching format, and teaching content. Ten schools used PBL. Teaching times from timetables were validated against two other studies that had assessed GP teaching and lecture, seminar, and tutorial times.

RESULTS

A total of 47,258 timetabled teaching events in the academic year 2014/2015 were analysed, including SSCs (student-selected components) and elective studies. A typical UK medical student receives 3960 timetabled hours of teaching during their 5-year course. There was a clear difference between the initial 2 years which mostly contained basic medical science content and the later 3 years which mostly consisted of clinical teaching, although some clinical teaching occurs in the first 2 years. Medical schools differed in duration, format, and content of teaching. Two main factors underlay most of the variation between schools, Traditional vs PBL teaching and Structured vs Unstructured teaching. A curriculum map comparing medical schools was constructed using those factors. PBL schools differed on a number of measures, having more PBL teaching time, fewer lectures, more GP teaching, less surgery, less formal teaching of basic science, and more sessions with unspecified content.

DISCUSSION

UK medical schools differ in both format and content of teaching. PBL and non-PBL schools clearly differ, albeit with substantial variation within groups, and overlap in the middle. The important question of whether differences in teaching matter in terms of outcomes is analysed in a companion study (MedDifs) which examines how teaching differences relate to university infrastructure, entry requirements, student perceptions, and outcomes in Foundation Programme and postgraduate training.

Exploring UK medical school differences: the MedDifs study of selection, teaching, student and F1 perceptions, postgraduate outcomes and fitness to practise

BACKGROUND

Medical schools differ, particularly in their teaching, but it is unclear whether such differences matter, although influential claims are often made. The Medical School Differences (MedDifs) study brings together a wide range of measures of UK medical schools, including postgraduate performance, fitness to practise issues, specialty choice, preparedness, satisfaction, teaching styles, entry criteria and institutional factors.

METHOD

Aggregated data were collected for 50 measures across 29 UK medical schools. Data include institutional history (e.g. rate of production of hospital and GP specialists in the past), curricular influences (e.g. PBL schools, spend per student, staff-student ratio), selection measures (e.g. entry grades), teaching and assessment (e.g. traditional vs PBL, specialty teaching, self-regulated learning), student satisfaction, Foundation selection scores, Foundation satisfaction, postgraduate examination performance and fitness to practise (postgraduate progression, GMC sanctions). Six specialties (General Practice, Psychiatry, Anaesthetics, Obstetrics and Gynaecology, Internal Medicine, Surgery) were examined in more detail.

RESULTS

Medical school differences are stable across time (median alpha = 0.835). The 50 measures were highly correlated, 395 (32.2%) of 1225 correlations being significant with p < 0.05, and 201 (16.4%) reached a Tukey-adjusted criterion of p < 0.0025. Problem-based learning (PBL) schools differ on many measures, including lower performance on postgraduate assessments. While these are in part explained by lower entry grades, a surprising finding is that schools such as PBL schools which reported greater student satisfaction with feedback also showed lower performance at postgraduate examinations. More medical school teaching of psychiatry, surgery and anaesthetics did not result in more specialist trainees. Schools that taught more general practice did have more graduates entering GP training, but those graduates performed less well in MRCGP examinations, the negative correlation resulting from numbers of GP trainees and exam outcomes being affected both by non-traditional teaching and by greater historical production of GPs. Postgraduate exam outcomes were also higher in schools with more self-regulated learning, but lower in larger medical schools. A path model for 29 measures found a complex causal nexus, most measures causing or being caused by other measures. Postgraduate exam performance was influenced by earlier attainment, at entry to Foundation and entry to medical school (the so-called academic backbone), and by self-regulated learning. Foundation measures of satisfaction, including preparedness, had no subsequent influence on outcomes. Fitness to practise issues were more frequent in schools producing more male graduates and more GPs.

CONCLUSIONS

Medical schools differ in large numbers of ways that are causally interconnected. Differences between schools in postgraduate examination performance, training problems and GMC sanctions have important implications for the quality of patient care and patient safety.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

Aquatic therapy for children with Duchenne muscular dystrophy: a pilot feasibility randomised controlled trial and mixed-methods process evaluation

BACKGROUND

Duchenne muscular dystrophy (DMD) is a rare disease that causes the progressive loss of motor abilities such as walking. Standard treatment includes physiotherapy. No trial has evaluated whether or not adding aquatic therapy (AT) to land-based therapy (LBT) exercises helps to keep muscles strong and children independent.

OBJECTIVES

To assess the feasibility of recruiting boys with DMD to a randomised trial evaluating AT (primary objective) and to collect data from them; to assess how, and how well, the intervention and trial procedures work.

DESIGN

Parallel-group, single-blind, randomised pilot trial with nested qualitative research.

SETTING

Six paediatric neuromuscular units.

PARTICIPANTS

Children with DMD aged 7-16 years, established on corticosteroids, with a North Star Ambulatory Assessment (NSAA) score of 8-34 and able to complete a 10-m walk without aids/assistance. Exclusions: > 20% variation between baseline screens 4 weeks apart and contraindications.

INTERVENTIONS

Participants were allocated on a 1 : 1 ratio to (1) optimised, manualised LBT (prescribed by specialist neuromuscular physiotherapists) or (2) the same plus manualised AT (30 minutes, twice weekly for 6 months: active assisted and/or passive stretching regime; simulated or real functional activities; submaximal exercise). Semistructured interviews with participants, parents (n = 8) and professionals (n = 8) were analysed using Framework analysis. An independent rater reviewed patient records to determine the extent to which treatment was optimised. A cost-impact analysis was performed. Quantitative and qualitative data were mixed using a triangulation exercise.

MAIN OUTCOME MEASURES

Feasibility of recruiting 40 participants in 6 months, participant and therapist views on the acceptability of the intervention and research protocols, clinical outcomes including NSAA, independent assessment of treatment optimisation and intervention costs.

RESULTS

Over 6 months, 348 children were screened - most lived too far from centres or were enrolled in other trials. Twelve (30% of target) were randomised to AT (n = 8) or control (n = 4). People in the AT (n = 8) and control (n = 2: attrition because of parental report) arms contributed outcome data. The mean change in NSAA score at 6 months was -5.5 [standard deviation (SD) 7.8] for LBT and -2.8 (SD 4.1) in the AT arm. One boy suffered pain and fatigue after AT, which resolved the same day. Physiotherapists and parents valued AT and believed that it should be delivered in community settings. The independent rater considered AT optimised for three out of eight children, with other children given programmes that were too extensive and insufficiently focused. The estimated NHS costs of 6-month service were between £1970 and £2734 per patient.

LIMITATIONS

The focus on delivery in hospitals limits generalisability.

CONCLUSIONS

Neither a full-scale frequentist randomised controlled trial (RCT) recruiting in the UK alone nor a twice-weekly open-ended AT course delivered at tertiary centres is feasible. Further intervention development research is needed to identify how community-based pools can be accessed, and how families can link with each other and community physiotherapists to access tailored AT programmes guided by highly specialised physiotherapists. Bayesian RCTs may be feasible; otherwise, time series designs are recommended.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN41002956.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 27. See the NIHR Journals Library website for further project information.

Enzyme-free nucleic acid dynamical systems

Chemistries exhibiting complex dynamics—from inorganic oscillators to gene regulatory networks—have been long known but either cannot be reprogrammed at will or rely on the sophisticated enzyme chemistry underlying the central dogma. Can simpler molecular mechanisms, designed from scratch, exhibit the same range of behaviors? Abstract chemical reaction networks have been proposed as a programming language for complex dynamics, along with their systematic implementation using short synthetic DNA molecules. We developed this technology for dynamical systems by identifying critical design principles and codifying them into a compiler automating the design process. Using this approach, we built an oscillator containing only DNA components, establishing that Watson-Crick base-pairing interactions alone suffice for complex chemical dynamics and that autonomous molecular systems can be designed via molecular programming languages.

Aquatic therapy for boys with Duchenne muscular dystrophy (DMD): an external pilot randomised controlled trial

BACKGROUND

Standard treatment of Duchenne muscular dystrophy (DMD) includes regular physiotherapy. There are no data to show whether adding aquatic therapy (AT) to land-based exercises helps maintain motor function. We assessed the feasibility of recruiting and collecting data from boys with DMD in a parallel-group pilot randomised trial (primary objective), also assessing how intervention and trial procedures work.

METHODS

Ambulant boys with DMD aged 7-16 years established on steroids, with North Star Ambulatory Assessment (NSAA) score ≥8, who were able to complete a 10-m walk test without aids or assistance, were randomly allocated (1:1) to 6 months of either optimised land-based exercises 4 to 6 days/week, defined by local community physiotherapists, or the same 4 days/week plus AT 2 days/week. Those unable to commit to a programme, with >20% variation between NSAA scores 4 weeks apart, or contraindications to AT were excluded. The main outcome measures included feasibility of recruiting 40 participants in 6 months from six UK centres, clinical outcomes including NSAA, independent assessment of treatment optimisation, participant/therapist views on acceptability of intervention and research protocols, value of information (VoI) analysis and cost-impact analysis.

RESULTS

Over 6 months, 348 boys were screened: most lived too far from centres or were enrolled in other trials; 12 (30% of the targets) were randomised to AT (n = 8) or control (n = 4). The mean change in NSAA at 6 months was -5.5 (SD 7.8) in the control arm and -2.8 (SD 4.1) in the AT arm. Harms included fatigue in two boys, pain in one. Physiotherapists and parents valued AT but believed it should be delivered in community settings. Randomisation was unattractive to families, who had already decided that AT was useful and who often preferred to enrol in drug studies. The AT prescription was considered to be optimised for three boys, with other boys given programmes that were too extensive and insufficiently focused. Recruitment was insufficient for VoI analysis.

CONCLUSIONS

Neither a UK-based RCT of AT nor a twice weekly AT therapy delivered at tertiary centres is feasible. Our study will help in the optimisation of AT service provision and the design of future research.

TRIAL REGISTRATION

ISRCTN41002956.

Urinary C-peptide analysis in an intervention study: experience from the DEFEND-2 otelixizumab trial

AIMS

To demonstrate that analysis of urinary C-peptide across multiple study sites in the context of an intervention trial (DEFEND-2) is a viable alternative to mixed meal testing and delivers results that correlate to mixed meal testing estimation of endogenous insulin production.

METHODS

Second morning void urine was collected for analysis and was available from 161 subjects at baseline (55 placebo, 106 otelixizumab), and 146 subjects (47 placebo, 99 otelixizumab) at month 12. Urinary C-peptide concentration was corrected for urinary creatinine [urinary C-peptide/creatinine ratio (UCPCR)] and serum C-peptide from the mixed meal tolerance test was calculated using area under the plasma concentration-time curve (AUC) normalized over 120 min. The correlation between mixed meal stimulated C-peptide AUC (mmol/l/min) and UCPCR (nmol/mmol), as well as the correlation between insulin use (IU/kg), and HbA_1c (%) with UCPCR, was determined.

RESULTS

UCPCR and mixed meal testing C-peptide AUC were correlated, with a correlation coefficient of 0.4172. UCPCR was not correlated with exogenous insulin use (r = -0.089) or with HbA_1c (r = -0.032).

CONCLUSIONS

Urinary C-peptide estimation should be considered as a measure of endogenous insulin production in future Type 1 diabetes mellitus outcome trials. A change in the timing for urine collection (to 120 min post standard meal) may provide a tighter correlation to C-peptide measured via a traditional mixed meal test.

Subcutaneous Administration of Otelixizumab is Limited by Injection Site Reactions: Results of an Exploratory Study in Type 1 Diabetes Mellitus Patients

Targeting CD3 antigens on human T lymphocytes with monoclonal antibodies has been shown to reduce the rate of decline of C-peptides in recent-onset type 1 diabetes mellitus patients. However, effective doses are associated with infusion reactions typical of "cytokine release syndrome" and appear to be dose-limiting when administered as short-duration infusions. A possible alternative approach, which may reduce the rate of T cell activation and consequent systemic cytokine release, is to inject subcutaneously. We investigated single- and repeat-dose subcutaneous administration of the anti-CD3 monoclonal antibody otelixizumab in small cohorts of patients with type 1 diabetes. Transient reductions in free or unbound CD3 antigen on CD4+ and CD8+ cells and absolute lymphocyte count were observed in the blood of these patients during treatment, consistent with the known mechanism of action of otelixizumab and other anti-CD3 monoclonal antibodies. This was despite the very low systemic exposure of antibodies measured during the same time period. With the exception of sporadic headaches, other symptoms associated with cytokine release syndrome, such as fever, nausea, vomiting, myalgia, and arthralgia, were absent in treated patients. However, treatment-related injection site reactions were consistently observed. The reactions were erythematous and their sizes were dose-dependent; in some cases, reactions persisted for up to 2 weeks following the start of treatment. While patients responded well to topical corticosteroid treatment and prophylaxis reduced the intensity of injection site reactions, the reactions were considered dose-limiting and higher doses were not investigated.

Efficacy and safety of low-dose otelixizumab anti-CD3 monoclonal antibody in preserving C-peptide secretion in adolescent type 1 diabetes: DEFEND-2, a randomized, placebo-controlled, double-blind, multi-centre study

AIMS

Phase III DEFEND-2 investigated whether otelixizumab (3.1 mg over 8 days) preserved C-peptide secretion in patients with new-onset Type 1 diabetes, focusing on adolescents (12-17 years).

METHODS

One hundred and seventy-nine patients (54 adolescents) were randomized to otelixizumab or placebo. The primary endpoint was change in 2-h mixed-meal-stimulated C-peptide area under the curve at month 12. Enrolment was suspended in April 2011 following negative efficacy results from DEFEND-1. DEFEND-2 terminated early after 12 months' efficacy and safety follow-up.

RESULTS

Change from baseline C-peptide was not significantly different [∆ = -0.09 nmol/l (95% CI -0.17 to 0; P = 0.051)]. No differential C-peptide effect was seen for otelixizumab in adolescents and more adverse events were reported.

CONCLUSIONS

Efficacy and tolerability of otelixizumab was similar to DEFEND-1. The 3.1-mg dose was non-efficacious in adults and adolescents. Further investigation of the mechanism of action seen at higher doses and therapeutic window is required. Clinical Trials Registry No: NCT 00763451.

Asthma control in a random sample of New Zealand adolescent asthmatics

Asthma control, defined by asthma symptoms and lung function, and asthma medication use, was assessed in 123 adolescent asthmatics. Sputum eosinophilia (>or= 2.5% eosinophils) and bronchial hyperresponsiveness (BHR) to hypertonic saline were also measured to assess whether these additional objective parameters might aid in determining asthma control; 54.5% of subjects had adequately controlled asthma; 50.4% of all subjects reported inhaled corticosteroid use in the preceding 12 months; however, only 22.3% reported regular use. Although BHR and median eosinophil numbers were significantly higher in the inadequately controlled asthmatics, BHR and sputum eosinophilia had poor sensitivity for detecting inadequate asthma control.

Baseline Resistance and Virological Outcome in Patients with Virological Failure who Start a Regimen Containing Abacavir: Eurosida Study

Objectives

To investigate the ability of several HIV-1 drug-resistance interpretation systems, as well as the number of pre-specified combinations of abacavir-related mutations, to predict virological response to abacavir-containing regimens in antiretroviral therapy-experienced, abacavir-naive patients starting an abacavir-containing regimen in the EuroSIDA cohort.

Patients and methods

A total of 100 HIV-infected patients with viral load (VL) >500 copies/ml who had a plasma sample available at the time of starting abacavir (baseline) were included. Resistance to abacavir was interpreted by using eight different commonly used systems that consisted of rules-based algorithms or tables of mutations. Correlation between baseline abacavir-resistance mutations and month 6 virological response was performed on this population using a multivariable linear regression model accounting for censored data.

Results

The baseline VL was 4.36 log10 RNA copies/ml [interquartile range (IQR): 3.65–4.99 log10 RNA copies/ml] and the median CD4 cell count was 210 cells/μl (IQR: 67–305 cells/μl). Our patients were pre-exposed to a median of seven antiretrovirals (2–12) before starting abacavir therapy. The median (range) number of abacavir mutations (according to the International AIDS Society-USA) detected at baseline was 3.5 (0–8). Overall, the Kaplan–Meier estimate of the median month 6 VL decline was 0.86 log10 RNA copies/ml [95% confidence intervals (95% CI): 0.45–1.24]. The VL in those patients ( n=31) who intensified treatment by adding only abacavir decreased by a median 0.20 log10 RNA copies/ml (95% CI: -0.18; +0.94). The proportion of patients who harboured viruses fully resistant to abacavir among the eight genotypic resistance interpretation algorithms ranged from 12% [Agence Nationale de Recherches sur le SIDA (ANRS)] to 79% [Stanford HIV RT and PR Sequence Database (HIVdb)]. Some interpretation systems showed statistically significant associations between the predicted resistance status and the virological response while others showed no consistent association. The number of active drugs in the regimen was associated with greater virological suppression (additional month 6 VL reduction per additional sensitive drug=0.51, 95% CI: 0.15–0.88, P=0.006); baseline VL was also weakly associated (additional month 6 VL reduction per log10 higher=0.30, 95% CI: -0.02; +0.62, P=0.06). In contrast, the number of drugs previously received was associated with diminished viral reduction (additional month 6 VL reduction per additional drug=-0.14, 95% CI: -0.28; 0.00, P=0.05).

Conclusions

Our results revealed a high degree of variability among several genotypic resistance interpretation algorithms currently in use for abacavir. Therefore, the interpretation of genotypic resistance for predicting response to regimens containing abacavir remains a major challenge.

Genotyping Demonstrates That the Strains of Proteus Mirabilis From Bladder Stones and Catheter Encrustations of Patients Undergoing Long-Term Bladder Catheterization are Identical

PURPOSE

We established the incidence of bladder stones in patients who experienced recurrent encrustation and blockage of indwelling bladder catheters and examined the relationship between isolates of Proteus mirabilis from the stones and from the crystalline biofilms on the catheters.

MATERIALS AND METHODS

The first 100 patients attending a clinic for patients experiencing problems with the management of long-term bladder catheters were studied. Flexible cystoscopy was used to detect bladder stones. Catheter encrustation was assessed visually and by electron microscopy. Bacteriological analysis was performed on the stones and catheter biofilms. P. mirabilis isolates were genotyped by pulsed field gel electrophoresis of restriction enzyme digests of bacterial DNA.

RESULTS

Most patients (85%) had been referred because of catheter blockage and in 61 (72%) the catheters were encrusted. P. mirabilis was recovered from 37 of 47 encrusted catheters (79%) that were examined but not from any nonencrusted catheters. Of the 61 patients with encrusted catheters 38 (62%) had bladder stones. Pairs of isolates of P. mirabilis from the stones and the catheter biofilms from 6 patients were genotyped. The DNA profiles of each pair of isolates were identical.

CONCLUSIONS

The majority of patients (62%) with recurrent catheter encrustation had bladder stones. The stones harbored the strains of P. mirabilis that rapidly colonize replacement catheters with crystalline biofilm. Flexible cystoscopy to detect and remove stones might help resolve the problem of recurrent catheter encrustation.

Developing alternative devices to the long-term urinary catheter for draining urine from the bladder

The self-retaining urinary catheter is used for long-term drainage of urine from the bladder only as a last resort because of serious associated complications, yet it remains a routine method for managing older and disabled patients with loss of bladder control. Blockage of the catheter from calcified deposits within its lumen is a common occurrence, obstructing the passage of urine and causing an urgent, unpredictable problem for patients, carers and the nursing staff. The need for further research on the subject has been recognized for many years. The SuPort Project aimed to develop an alternative suprapubic urine collection system. This report outlines the approach adopted towards the design and selection of the novel device, the production problems that ensued and the small clinical trial of a modified prototype.

Endoluminal ultrasonography before retrograde endopyelotomy: can the results match laparoscopic pyeloplasty?

OBJECTIVE

To present the results of endopyelotomy using endoluminal ultrasonography (EUS) to identify crossing vessels, as the success rates of endopyelotomy are generally lower than pyeloplasty, especially in patients with crossing vessels.

PATIENTS AND METHODS

Forty-one consecutive patients who underwent EUS before a planned retrograde endopyelotomy were analysed retrospectively. EUS was used to direct the endopyelotomy incision for patients with crossing vessels. Treatment was considered successful if the patient was asymptomatic and unobstructed or improved on renography. The results were compared to those from 18 patients treated by laparoscopic pyeloplasty, some of whom had undergone EUS.

RESULTS

Crossing vessels were identified in 27 of the 41 patients (66%). Primary treatment consisted of endopyelotomy for 26 patients and laparoscopic pyeloplasty for 15. The overall success rate for 24 endopyelotomy patients with an adequate follow-up (mean 19 months) was 71%, with more success in patients with no crossing vessels (11 of 13 (85%) vs six of 11 (55%)). Of the 18 patients treated by laparoscopic pyeloplasty (mean follow-up 15.1 months) 17 were successful.

CONCLUSION

The results for endopyelotomy were disappointing in patients with crossing vessels, despite using EUS. The results suggest that patients with crossing vessels should be treated by laparoscopic pyeloplasty. More data are needed to compare endopyelotomy with laparoscopic pyeloplasty in patients with no crossing vessels.

Flexible ureteroscopes: a user's guide

OBJECTIVE

To compare, quantitatively and qualitatively, four small-diameter flexible ureteroscopes.

MATERIALS AND METHODS

Four flexible ureteroscopes from different manufacturers, i.e. the DUR-8 (ACMI, Southborough, MA, USA), Olympus UPF-3 (Keymed, Southend-on-Sea, UK), Storz 11274AA (Karl Storz GmbH, Tuttlingen, Germany) and the Wolf 9 F (Henke Sass Wolf GmbH, Tuttlingen, Germany), were assessed quantitatively by measuring the active tip deflection and irrigation flow rate with laser fibres (200 micro m, 365 micro m), an electrohydraulic lithotripter (1.9 F) and grasping forceps (3 F) in position. They were then assessed subjectively by two endourologists who scored them, using a visual analogue scale (maximum 10), for insertion, deflection mechanism, manoeuvrability, rigidity, image quality and overall satisfaction.

RESULTS

All the endoscopes are < 9 F at the tip, although the length of the smallest diameter (bevelled tip vs section of shaft) was variable. Tip deflection was 87-100% of the manufacturers' specifications and decreased by similar percentages with instruments in the working channel. The irrigation flow rate was comparable for instruments with a 3.6 F working channel (72-88 mL/min with an empty working channel), although much greater for the Wolf, which has a 4 F channel (116 mL/min). Direction and image size were nearly identical, as was the field of view, apart from the Wolf (60 degrees vs 90 degrees ). There was agreement in the user assessment for three instruments, with overall satisfaction scores being Storz (4), ACMI (7.5) and Olympus (8.6), but disagreement in scores for Wolf (1.9 vs 5.3).

CONCLUSIONS

Whilst there were considerable similarities in the objective assessment among the instruments, the user assessment showed qualitative variability. Thus it is important to try the different instruments before selecting one. Additional variables to consider include durability, cost and service/warranty, which vary considerably among instruments.

Urinary catheter 'deflation cuff' formation: clinical audit and quantitative in vitro analysis

OBJECTIVE

To investigate reports from district nursing staff of difficulty in removing long-term urinary catheters (LTCs) because of the formation of a 'cuff' on deflating the self-retaining balloon.

PATIENTS AND METHODS

Problems experienced by district nurses when removing urethral and suprapubic LTCs were audited, noting the type of problem, the catheter and any action taken. Quantitative in vitro studies were conducted on the deflated self-retaining balloons after incubating a similar range of catheters in saline at 37 degrees C for 6 weeks, using suprapubic profilometry to assess the resistance to withdrawal (retention force).

RESULTS

Questionnaires were returned on 154 patients with LTCs; 56% had urethral and 44% suprapubic catheters. The catheters were hydrogel-coated (83%), all-silicone (13%) and PTFE-coated (3%). Twenty-two (14%) of the sample reported problems with catheter removal in the previous year, including 15 (68%) with all-silicone catheters and 15 (68%) with suprapubic catheters; cuff formation was noted in 60%. In the laboratory, 10 of the balloons formed a 'cuff' on deflation, but there was great variability in the effect this had on the retention force, with values of 0.5-3 N for different catheters.

CONCLUSIONS

Most problems with catheter removal involved all-silicone and suprapubic catheters. Suprapubic profilometry confirmed increased resistance to withdrawal by formation of a 'cuff' on deflation of the balloon of all-silicone catheters. These results suggest that the first choice of catheter material for long-term urethral and suprapubic use should be hydrogel-coated latex.

Re-auditing a regional lithotripsy service

OBJECTIVE

To assess, in a repeat audit of a regional lithotripsy service, whether changes implemented after a regional audit in 1994 (which showed disappointing results from shock wave lithotripsy, attributable to both poor patient selection and an inadequate fixed-site lithotripter) have had any effect.

PATIENTS AND METHODS

A data-collection sheet was devised to gather information on the site, size and number of stones treated, together with information on the lithotripsy treatment and outcome. Patients selected for the audit were the first 50 new patients treated with lithotripsy at each centre in 1999. As only one hospital has a fixed-site lithotripsy machine, the results of mobile lithotripsy were grouped by machine for analysis.

RESULTS

There was an overall improvement in patient selection from the previous audits. Few stones of > 16 mm or < 4 mm were treated. Two units treated more ureteric stones, thought to reflect first the influence of a fixed-site lithotripter, and second a willingness to insert a ureteric stent and await the next mobile lithotripter visit. The stone free rates were all disappointingly low (16.7-26.7%) but the results improved when fragments of < 4 mm were included as "successful" giving an "overall success rate" of 45.9-66.7%. The unit with a fixed-site lithotripter appeared to perform better (two-thirds successful) than the mobile machines (Modulith SLX, 51%; Modulith SLK, 46%). One centre visited by both mobile machines had a success rate of 65% but a high rate of auxiliary procedures (35% vs 16-19% vs the fixed-site).

CONCLUSION

Although these results show some improvement in patient selection for our regional lithotripsy service, stone-free and success rates are poorer than those reported elsewhere. This may reflect the modern lithotripsy machines that allow day-case treatment with minimal analgesia, and confirms reports by other authors who encourage a re-examination of success rates of shock wave lithotripsy.

Response to Antiretroviral Therapy among Patients Exposed to Three Classes of Antiretrovirals: Results from the Eurosida Study

There is an increasing proportion of HIV-positive patients exposed to all licensed classes of antiretrovirals, and the response to salvage regimens may be poor. Among over 8500 patients in EuroSIDA, the proportion of treated patients exposed to nucleosides, protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitor (NNRTI) increased from 0% in 1996 to 47% in 2001. Four-hundred-and-thirteen patients, who had failed virologically two highly active antiretroviral therapy (HAART) regimens and experienced all three main drug classes, started a salvage regimen of at least three drugs, in which at least one new PI or NNRTI was included. Median viral load was 4.7 log copies/ml [Interquartile range (IQR) 4.2–5.2], CD4 lymphocyte count 150/mm3 (IQR 60–274/mm3) and follow-up 14 months. Of these patients, 283 (69%) subsequently experienced at least a 1 log decline in viral load and 202 (49%) achieved a viral load <500 copies/ml. Conversely, the CD4 count halved from the baseline value in 88 (21%), and 45 (11%) experienced a new AIDS-defining disease. In multivariable analyses, a 1 log viral load reduction was related to baseline viral load [relative hazard (RH) 1.27 per 1 log higher; P=0.008], a previous viral load of less than 500 copies/ml (RH 1.69; P=0.002), more recent initiation of the regimen (RH 1.36 per year more recent; P=0.02), number of new drugs in the regimen (RH 1.20 per drug; P=0.02), time since start of antiretroviral therapy (RH 0.94 per extra year; P=0.035) and time spent on HAART with viral load >1000 copies/ml (RH 0.96 per extra month; P=0.0001). Analysis of factors associated with CD4 count decline and new AIDS disease also indicated improved outcomes in more recent times and a tendency for a better response in those starting more new drugs, but no relationship with the total number of drugs. Outcomes in people starting salvage regimens appear to depend on the number of new drugs started but not on the total number of drugs being used.

Laparoscopic lymph node sampling in locally advanced prostate cancer

OBJECTIVE

To assess the role of laparoscopic lymph node sampling in patients with locally advanced prostate cancer before radical radiotherapy, and to show that the procedure is safe when carried out by urologists with the appropriate training.

PATIENTS AND METHODS

Patients were selected prospectively using a combination of prostate-specific antigen (PSA) level, clinical stage and Gleason grade, which predicted a > 20% risk of lymph node metastases. Between October 1998 and March 2001, 50 patients (mean age 65 years, range 54-78) underwent laparoscopic pelvic lymphadenectomy. Age, presenting PSA level, Gleason grade, clinical stage, operative time, length of stay, and any adverse events were recorded. The histology reports were reviewed for the presence of nodal metastases. The selection criteria were compared between the groups with and with no nodal metastases.

RESULTS

The mean (range) PSA level of the men was 36.8 (4.4-184) ng/mL and the Gleason grade 6.8 (4-9); 58% had stage T3 disease and 12 patients (24%) had lymph node metastases. There were no statistically significant differences in PSA, Gleason grade or clinical stage between those with positive or negative nodes. The mean operative duration was 110 min, although this decreased from 133 min for the first 10 cases; one case was converted to an open procedure. The median (range) postoperative stay was 1 (1-12) days. There were two major (5%) and seven (17%) minor complications.

CONCLUSIONS

This study confirms that laparoscopic lymph nodes can be sampled safely by urologists with experience in laparoscopic surgery. Patients with a significant risk of metastases can be selected preoperatively using a combination of PSA, clinical stage and Gleason grade. Lymph node sampling in this group is necessary, as there is no other method of reliably identifying the subgroup of patients with metastatic disease in which radical conformal radiotherapy cannot be justified.

An overview of the immune system

We are continually exposed to organisms that are inhaled, swallowed, or inhabit our skin and mucous membranes. Whether these organisms penetrate and cause disease is a result of both the pathogenicity of the organism (the virulence factors at its disposal) and the integrity of host defence mechanisms. The immune system is an interactive network of lymphoid organs, cells, humoral factors, and cytokines. The essential function of the immune system in host defence is best illustrated when it goes wrong; underactivity resulting in the severe infections and tumours of immunodeficiency, overactivity in allergic and autoimmune disease. In this review we have covered the normal function of the immune system in recognising, repelling, and eradicating pathogens and other foreign molecules.

Evidence-based practice: the arguments for and against

The term evidence-based practice is becoming increasingly common within the health care sector. This is not only because of a search for quality, but also because of economic factors which demand more effective use of resources. This article will present some of the arguments which both support and oppose evidence-based practice. These arguments may at times appear to be contradictory in nature. The implications of evidence-based practice, for both patients and health care workers, is considered.

Intravesical dimethyl sulfoxide (DMSO) for interstitial cystitis--a practical approach

OBJECTIVES

To provide a brief overview of intravesical dimethly sulfoxide (DMSO) therapy for interstitial cystitis and offer a practical approach to patient treatment.

METHODS

A review of the literature and a summation of the experience with treatment of > 300 patients with DMSO at the Interstitial Cystitis Clinic, New England Medical Center.

RESULTS

DMSO is helpful in a significant number of patients and it has acceptable morbidity and an excellent safety profile.

CONCLUSIONS

Intravesical DMSO (singly or in combination) is one of the mainstays in the pharmacologic treatment of interstitial cystitis.

Uveitis associated with rifabutin and macrolide therapy for Mycobacterium avium intracellulare infection in AIDS patients

OBJECTIVE

Uveitis has been increasingly recognised as a side effect of rifabutin regimens in the prophylaxis and treatment of Mycobacterium avium intracellulare (MAI) infection. This study describes the clinical features and analyses the factors associated with rifabutin induced uveitis.

DESIGN

Retrospective observational study.

SETTING

Tertiary care institution, The Royal Hospitals NHS Trust, London.

PATIENTS

68 HIV seropositive individuals receiving rifabutin for prophylaxis or treatment of MAI infection.

RESULTS

11 episodes of uveitis occurred in 10 different individuals at a median of 62 days. The disease was bilateral in four and unilateral in the remainder. All subjects experienced ocular pain and photophobia and 9 individuals had a significant reduction in visual acuity. Uveitis was treated with mydriatics and topical steroids and resolved in all cases when rifabutin was stopped. The risk of uveitis was significantly increased with concurrent clarithromycin therapy, Odds Ratio 13.08, 95% Confidence Interval 1.98 to 83.12.

CONCLUSION

Rifabutin can cause a reversible uveitis. This risk is increased with concurrent clarithromycin therapy. Adverse drug interactions can be an important cause of morbidity in patients with advanced HIV disease.

Eutectic mixture of local anaesthetics is not effective for extracorporeal shock wave lithotripsy

PURPOSE

Eutectic mixture of local anaesthetics (EMLA) produces cutaneous analgesia. This randomized, double blind, placebo controlled study evaluated the efficacy of EMLA cream during extracorporeal shock wave lithotripsy (ESWL) using the Dornier MFL 5000 lithotripter.

METHODS

Patients scheduled to undergo lithotripsy of renal or pelviureteric junction stones were randomized to receive either 30 g EMLA cream (E) or placebo (P) over the kidney area 60-90 min before the procedure. During lithotripsy all patients received alfentanil via a PCA machine (dose--10 mu.kg-1, lockout time--three minutes, no basal infusion). Additional bolus doses of 5 micrograms.kg-1 alfentanil were administered by the anaesthetist if analgesia was inadequate. Visual analogue scores (VAS) for pain were documented prior to application of the cream. On arrival in the post anaesthesia care unit VAS pain scores were documented for maximum pain and average pain felt during the procedure as well as for satisfaction of the analgesic technique used. Total time spent in the PACU and the Aldrete scores on arrival were compared.

RESULTS

Eighty-three patients completed the study. Demographic data were similar between the two groups. Also, VAS for maximal pain, average pain and satisfaction and the total number of shock waves were similar although the EMLA group received more shock waves at the lower energy level (kV) (P < 0.0001). Total dose of alfentanil, dose as boluses, rate of alfentanil use, total number of PCA attempts and missed attempts were similar. The incidence of adverse events such as bradypnoea, airway obstruction, transient hypoxaemia, pruritus and nausea were small and similar. There was a slightly higher incidence of inadequate analgesia documented by the anaesthetist in the EMLA group. There was no difference between the groups with regards to duration of stay in the PACU, incidence of nausea or Aldrete scores on admission to PACU.

CONCLUSIONS

During lithotripsy EMLA cream does not modify the pain perceived nor does it have any opioid sparing effect. It does not facilitate early discharge from the PACU.

High response rates with short infusional 2-chlorodeoxyadenosine in de novo and relapsed low-grade lymphoma. Australian and New Zealand Lymphoma Study Group

Thirty-five patients (eight de novo, 27 relapsed disease) with low-grade non-Hodgkin's lymphoma (diffuse small lymphocytic, follicular small cleaved cell, follicular mixed cell, and lymphoplasmacytoid) were treated with 2-chlorodeoxyadenosine (2CdA) at a daily dose of 0.14 mg/kg for 5d (2 h infusion) for an average of three cycles. Minor treatment delays, generally due to haematological toxicities, occurred in nine of 105 cycles. Major toxicities were lymphopenia, neutropenia and thrombocytopenia. Opportunistic infections occurred in seven patients. Overall response rate was 69% (five complete, 19 partial) reaching 88% for de novo patients (two complete, five partial). Elevated beta 2-microglobulin level was negatively predictive of response (P = 0.0014). Eight of 24 responders relapsed, with a median follow-up of 13 months. 2CdA administered as an intermittent infusion shows considerable single-agent activity in low-grade lymphomas achieving high response rates of prolonged duration. Consideration of schedules where 2CdA is alternatively administered with combination chemotherapy appears warranted.

The haemolytic uraemic syndrome in patients with AIDS

OBJECTIVE

Thrombotic microangiopathies have been increasingly recognised in HIV infection. The contribution of haemolytic uraemic syndrome (HUS) has not received as much emphasis as other members of the thrombotic microangiopathies. We describe the clinical features and prognosis of HUS in a group of patients with AIDS.

SETTING

St Bartholomew's and The Middlesex Hospitals, London.

PATIENTS

Five HIV seropositive individuals with clinical and histological features consistent with HUS.

INTERVENTIONS

Blood transfusion, fresh frozen plasma, haemodialysis, renal biopsy, autopsy.

CONCLUSIONS

HUS occurs in advanced HIV infection. Hypertension was a prominent clinical feature in HUS in this patient group. Measures to limit renovascular damage were unsuccessful and haemodialysis was usually needed to support renal function. The prognosis is poor, no patient achieved clinical remission and all died.

Glutamate exocytosis from cerebellar granule cells: the mechanism of a transition to an L-type Ca2+ channel coupling

When cerebellar granule cells in the presence of 1.3 mM calcium chloride (Ca2+) are depolarized by high potassium chloride (KCl), the release of endogenous glutamate is coupled to a high threshold Ca2+ channel blocked by the spider toxin omega Agatoxin-glutamate-release-inhibitor (Aga-GI) and insensitive to the L-type voltage-dependent Ca2+ channel-inhibitor nifedipine. A prolonged KCl depolarization in the absence of Ca2+ followed by addition of 5 mM Ca2+ results in an enhanced nifedipine-sensitive Ca2+ entry; glutamate exocytosis retains sensitivity to tetanus toxin and bafilomycin A1, is now totally inhibited by nifedipine and shows greatly reduced sensitivity to AGA-GI. Single cell Ca2+ imaging indicates that the L-type channel modulating release is preferentially located at somatic regions rather than neurites. A different pattern of vesicle endocytosis monitored with the fluorescent indicator FM1-43 is seen in response to the two depolarization protocols. Furthermore, vesicles loaded during depolarization with high KCl in the presence of 5 mM Ca2+ extensively exocytose dye in a nifedipine-insensitive manner in response to a second similar stimulation but release little dye in response to stimulus with high KCl in the absence of Ca2+ followed by the addition of 5 mM Ca2+. In contrast, vesicles loaded by stimulating with KCl in the absence of Ca2+ followed by the addition of 5 mM Ca2+ can be released by a second similar stimulus and this release is sensitive to nifedipine. Nifedipine sensitivity is not induced in cerebellar synaptosomes subjected to stimulation with high KCl in the absence of Ca2+ followed by the re-addition of 5 mM Ca2+. The results indicate that different populations of channels and vesicles may be functional during two depolarization protocols.

Factors influencing attendance at OHS programmes

Securing employee attendance at occupational health and safety programmes remains a problem for many OH departments. Jane Parkin's study looked at the possible factors influencing an individual's use of an OH service.

Iron overload in multiply transfused patients who are HIV seropositive

AIMS

To assess histologically the amount of iron deposited in liver biopsy specimens from HIV positive patients; and to perform estimations of liver iron on tissue from patients with an increase in parenchymal stainable iron. To correlate the amount of blood transfused and the degree of iron overload.

METHODS

Liver biopsy specimens (n = 120) from 109 HIV positive patients, 74 of whom had AIDS, were examined retrospectively and the amount of iron, as visualised with Perls's stain, was graded. Fibrosis was assessed using connective tissue stains. Estimations of liver iron were performed on tissue retrieved from paraffin wax blocks in cases with histological grade 3 or 4 iron overload. The amount of blood transfused before liver biopsy was determined from the notes for each patient.

RESULTS

Fifteen of the 120 liver biopsy specimens had significantly increased amounts of iron in their hepatocytes, as assessed histologically, and this was confirmed in seven cases by measurement of liver iron. There was a close correlation between the amount of blood transfused and the degree of iron overload. In the initial biopsy specimens only one case showed portal tract expansion. Three of the five patients who had repeat biopsies, however, showed progressive fibrosis.

CONCLUSION

Multiply transfused HIV positive patients may develop clinically important iron overload and are at risk of developing progressive fibrosis. Superimposed liver disease, especially viral hepatitis, in these high risk patients may exacerbate the effects of the iron overload.

Double-staining artefact observed in certain individuals during dual-colour immunophenotyping of lymphocytes by flow cytometry

An unusual double-staining artefact has been repeatedly observed in certain individuals (both HIV-positive and healthy laboratory controls) during 2-colour immunophenotyping of lymphocytes by flow cytometry after red cell lysis. This artefact can falsely suggest co-expression of CD4 and CD8, as well as some of the other monoclonal antibody pairs commonly used in the typing of lymphocytes. It is caused by a serum factor associated with the ammonium-sulphate-precipitated and gamma-globulin fractions. It appears to be fairly common in the population (being found in 6 out of 105 of our healthy laboratory controls and in 42 out of 247 of our HIV-1 seropositive subjects); it may be genetically determined, but may be acquired in some. It is a potential source of error in lymphocyte immunophenotyping, which can be avoided by simple adjustments to the recommended techniques.

Lymphoproliferative process with natural killer cell phenotype. Histopathologic, ultrastructural, and surface marker observations

We describe the clinical, structural, and immunophenotypic characteristics of a lymphoproliferative process characterized by persistent thrombocytopenia and prominent involvement of the spleen and, to a lesser degree, the liver. The proliferating cells lacked cytoplasmic azurophilic granules by light microscopy and on ultrastructural examination displayed prominent interdigitating cell processes and did not contain parallel tubular arrays. Immunophenotypically, the cells displayed markers of true natural killer cells (positive CD2, CD56, CD45, CD7, CD16, and CD33). No involvement of peripheral blood or bone marrow was detected. This case represents a proliferation of true natural killer cells probably arising in the spleen. The relationship of this process to other lymphoid proliferations at different sites with true natural killer cell or natural killer-like activity is unknown.