Screening for small molecule inhibitors of SAH nucleosidase using an SAH riboswitch

Due to the emergence of multidrug resistant pathogens, it is imperative to identify new targets for antibiotic drug discovery. The S-adenosylhomocysteine (SAH) nucleosidase enzyme is a promising target for antimicrobial drug development due to its critical functions in multiple bacterial processes including recycling of toxic byproducts of S-adenosylmethionine (SAM)-mediated reactions and producing the precursor of the universal quorum sensing signal, autoinducer-2 (AI-2). Riboswitches are structured RNA elements typically used by bacteria to precisely monitor and respond to changes in essential bacterial processes, including metabolism. Natural riboswitches fused to a reporter gene can be exploited to detect changes in metabolism or in physiological signaling. We performed a high-throughput screen (HTS) using an SAH-riboswitch controlled β-galactosidase reporter gene in Escherichia coli to discover small molecules that inhibit SAH recycling. We demonstrate that the assay strategy using SAH riboswitches to detect the effects of SAH nucleosidase inhibitors can quickly identify compounds that penetrate the barriers of Gram-negative bacterial cells and perturb pathways involving SAH.

Identification of Efflux Substrates Using a Riboswitch-Based Reporter in Pseudomonas aeruginosa

Pseudomonas aeruginosa is intrinsically resistant to many classes of antibiotics, reflecting the restrictive nature of its outer membrane and the action of its numerous efflux systems. However, the dynamics of compound uptake, retention, and efflux in this bacterium remain incompletely understood. Here, we exploited the sensor capabilities of a Z-nucleotide-sensing riboswitch to create an experimental system able to identify physicochemical and structural properties of compounds that permeate the bacterial cell, avoid efflux, and perturb the folate cycle or de novo purine synthesis. In the first step, a collection of structurally diverse compounds enriched in antifolate drugs was screened for ZTP (5-aminoimidazole-4-carboxamide riboside 5'-triphosphate) riboswitch reporter activity in efflux-deficient P. aeruginosa, allowing us to identify compounds that entered the cell and disrupted the folate pathway. These initial hits were then rescreened using isogenic efflux-proficient bacteria, allowing us to separate efflux substrates from efflux avoiders. We confirmed this categorization by measuring intracellular levels of select compounds in the efflux-deficient and -proficient strain using high-resolution liquid chromatography-mass spectrometry (LC-MS). This simple yet powerful method, optimized for high-throughput screening, enables the discovery of numerous permeable compounds that avoid efflux and paves the way for further refinement of the physicochemical and structural rules governing efflux in this multidrug-resistant Gram-negative pathogen. IMPORTANCE Treatment of Pseudomonas aeruginosa infections has become increasingly challenging. The development of novel antibiotics against this multidrug-resistant bacterium is a priority, but many drug candidates never achieve effective concentrations in the bacterial cell due to its highly restrictive outer membrane and the action of multiple efflux pumps. Here, we develop a robust and simple reporter system in P. aeruginosa to screen chemical libraries and identify compounds that either enter the cell and remain inside or enter the cell and are exported by efflux systems. This approach enables the development of rules of compound uptake and retention in P. aeruginosa that will lead to more rational design of novel antibiotics.

Inhibition of Macrophage Migration Inhibitory Factor by a Chimera of Two Allosteric Binders

Human Macrophage Migration Inhibitory Factor (MIF) is a trimeric cytokine implicated in a number of inflammatory and autoimmune diseases and cancer. We previously reported that the dye p425 (Chicago Sky Blue), which bound MIF at the interface of two MIF trimers covering the tautomerase and allosteric pockets, revealed a unique strategy to block MIF's pro-inflammatory activities. Structural liabilities, including the large size, precluded p425 as a medicinal chemistry lead for drug development. We report here a rational design strategy linking only the fragment of p425 that binds over the tautomerase pocket to the core of ibudilast, a known MIF allosteric site-specific inhibitor. The chimeric compound, termed L2-4048, was shown by X-ray crystallography to bind at the allosteric and tautomerase sites as anticipated. L2-4048 retained target binding and blocked MIF's tautomerase CD74 receptor binding, and pro-inflammatory activities. Our studies lay the foundation for the design and synthesis of smaller and more drug-like compounds that retain the MIF inhibitory properties of this chimera.

The Benefits of Streamlined Hip Fracture Management in a Regional Hospital

Introduction:

Hip fracture is an increasingly common injury in the growing elderly population. The morbidity and mortality associated with this injury can be reduced by minimizing delays to surgical treatment. We describe the impact of a regional hospital service redesign project that utilized the principles of smart simplicity, a management strategy that lays emphasis on collaboration to achieve desired goals.

Methods:

Prior to the redesign, patients with hip fractures were taking an average of 72 hours for surgical treatment. A hip fracture working group was created to examine closely the process of hip fracture care, and a single key performance indicator (KPI) of “surgery within 48 hours” was adopted. This allowed identification of processes that could be clarified and streamlined, with the agreement of relevant stakeholders, in the creation of a new hip fracture pathway.

Results:

In the first 3 months of the pathway’s implementation, 16 of 18 patients had surgery within 48 hours of presentation. In a 6-month follow-up audit after 2 years of implementation, 36 of 39 patients were treated within 48 hours. This was significantly different to the time to surgery seen in the 12 months prior to the redesign (P < .001, Student t test). The mean time to surgery was reduced from 72 hours to 36 hours, a saving in an annual acute bed stay cost of A$152 000.

Discussion:

Decreased time to the operating room, the cost savings inherent to this, can be achieved with the introduction of the best standard of care. A redesign that mandates collaboration in achieving a single KPI has allowed a significant culture shift in the treatment of hip fractures in our institution in the months following its institution.

Conclusion:

Collaborative, multidisciplinary collaboration has facilitated a higher standard of care and demonstrated significant cost benefit.

Reducing time to surgery after anterior cruciate ligament injury

Introduction

Recent work suggests that reconstruction of the ruptured anterior cruciate ligament within 12 months of injury results in better outcomes. We present a complete audit cycle examining the effect of establishment of an Acute Knee Clinic on time to surgery.

Methods

Records of 20 anterior cruciate ligament reconstructions undertaken by the senior author between June 2003 and May 2004 were examined to identify the time to surgery. The Acute Knee Clinic was established in December 2004. Prospectively collected data on patients attending the Acute Knee Clinic between May 2005 and July 2007 and patients undergoing anterior cruciate ligament reconstruction from September 2006 to 2007 were reviewed with respect to referral route, time from injury to specialist review and time to surgery.

Results

Mean time from injury to surgery of the initial cohort was 14 months (range 3–56). After establishment of the Acute Knee Clinic, 90% of referrals from Accident and Emergency (A&E) were seen by a specialist within four weeks. Between September 2006 and September 2007, 49 patients underwent anterior cruciate ligament reconstruction: 21 came via the Acute Knee Clinic, with a mean time from injury to surgery of 6 months; 28 patients from the elective clinic had a mean time to surgery of 25 months. 95% of Acute Knee Clinic patients and 53 % of elective clinic patients had surgery within 12 months of injury.

Discussion

The Acute Knee Clinic has been shown to reduce the time from injury to anterior cruciate ligament reconstruction. The Acute Knee Clinic only accounts for the referral of 40% of anterior cruciate ligament reconstructions in this series: Further education work is required with A&E staff and GPs regarding the referral of knee injuries. Access to the Acute Knee Clinic could be extended to GPs, although this could create service overload.

If a trauma patient is tachycardic, should we call for a counsellor?

BACKGROUND

It has been suggested in the literature that raised heart rate in the early period after trauma is associated with the development of post-traumatic psychopathology, but little account has been taken of the potential confounding effect of injury severity.

MATERIALS AND METHODS

A cohort of 154 patients, studied as part of a wider investigation of trauma outcomes, was included. Initial heart rate in the accident & emergency department, and injury severity score and new injury severity scores were recorded. Patients completed the General Health Questionnaire (GHQ-28) as a measure of psychopathology at presentation and again at two- and six-month follow-up.

RESULTS

There was no relationship between psychopathology at presentation and initial heart rate or injury severity. Raised heart rate was associated with post-traumatic psychopathology at two months but not at six months. When the potential confounding effect of injury severity was controlled for, there was no independent correlation between heart rate and post-traumatic psychopathology. Injury severity score and new injury severity scores were strongly associated with GHQ-28 caseness.

CONCLUSION

Post-traumatic tachycardia is not associated with development of psychopathology, but injury severity is. Previous studies that have suggested a link between tachycardia and development of psychopathology are flawed because they have not considered the confounding effect of severity of injury.

Is Anterior Cruciate Reconstruction Superior to Conservative Treatment?

Not all patients who have a rupture of the anterior cruciate ligament (ACL) elect to have surgical reconstruction. The aim of this study was to assess the short-to-medium-term results of patients who chose conservative management in comparison to patients who had reconstructive surgery within the same time period. Sixty-three patients with an ACL injury were retrospectively studied. Forty patients were managed, according to patient choice, with ACL reconstruction and 23 conservatively. Four validated questionnaires were used to assess general and knee-specific function in a cohort with a median age of 32 years and a median follow-up period of 38 months. Patients were matched on demographic variables except for gender. There were no statistically significant differences in the outcome measures, and the majority of patients would proceed with the same treatment in the event the control leg became injured. Patients who elect to have conservative management of an ACL rupture can achieve similar function and satisfaction to those who elect to have reconstruction. Until a large randomized controlled trial is conducted, patients need to be made aware of the merits of both management strategies and the lack of evidence of superiority of one over the other.

Analysis of sequential cytokine release after ACL reconstruction

PURPOSE

Rupture of the anterior cruciate ligament is common and may necessitate surgical reconstruction. Surgical reconstruction aims to restore normal kinematics and biology within the knee. The acute phase response after surgical reconstruction remains poorly defined but may influence graft integration through modulation of host tissue remodelling.

METHODS

The very early host production of key cytokines after surgery was studied. A consecutive series of 14 patients undergoing reconstructive surgery were studied per-operatively, 1 and 6 h after surgery, examining the hypothesis that the acute phase response would be non-specific but consistent between individuals, demonstrating increases of pro-inflammatory cytokines.

RESULTS

A consistent increased release of monocyte-driven, non-specific, IL-1 and IL-6 release but not T cell-derived IL-2 was found. Perhaps, more interestingly, very early high concentrations of secondary growth factors PDGF and TGF-β suggestive of an anabolic response were found.

CONCLUSION

These data support the contention that an anabolic response starts earlier than previously thought within the surgically reconstructed knee.

Design and SAR of macrocyclic Hsp90 inhibitors with increased metabolic stability and potent cell-proliferation activity

A novel series of macrocyclic ortho-aminobenzamide Hsp90 inhibitors is reported. A basic nitrogen within the tether linking the aniline nitrogen atom to a tetrahydroindolone moiety allowed access to compounds with good physical properties. Important structure-activity relationship information was obtained from this series which led to the discovery of a soluble and stable compound which is potent in an Hsp90 binding and cell-proliferation assay.

Developing a placebo-controlled trial in surgery: issues of design, acceptability and feasibility

Background

Surgical placebos are controversial. This in-depth study explored the design, acceptability, and feasibility issues relevant to designing a surgical placebo-controlled trial for the evaluation of the clinical and cost effectiveness of arthroscopic lavage for the management of people with osteoarthritis of the knee in the UK.

Methods

Two surgeon focus groups at a UK national meeting for orthopaedic surgeons and one regional surgeon focus group (41 surgeons); plenary discussion at a UK national meeting for orthopaedic anaesthetists (130 anaesthetists); three focus groups with anaesthetists (one national, two regional; 58 anaesthetists); two focus groups with members of the patient organisation Arthritis Care (7 participants); telephone interviews with people on consultant waiting lists from two UK regional centres (15 participants); interviews with Chairs of UK ethics committees (6 individuals); postal surveys of members of the British Association of Surgeons of the Knee (382 surgeons) and members of the British Society of Orthopaedic Anaesthetists (398 anaesthetists); two centre pilot (49 patients assessed).

Results

There was widespread acceptance that evaluation of arthroscopic lavage had to be conducted with a placebo control if scientific rigour was not to be compromised. The choice of placebo surgical procedure (three small incisions) proved easier than the method of anaesthesia (general anaesthesia). General anaesthesia, while an excellent mimic, was more intrusive and raised concerns among some stakeholders and caused extensive discussion with local decision-makers when seeking formal approval for the pilot.

Patients were willing to participate in a pilot with a placebo arm; although some patients when allocated to surgery became apprehensive about the possibility of receiving placebo, and withdrew. Placebo surgery was undertaken successfully.

Conclusions

Our study illustrated the opposing and often strongly held opinions about surgical placebos, the ethical issues underpinning this controversy, and the challenges that exist even when ethics committee approval has been granted. It showed that a placebo-controlled trial could be conducted in principle, albeit with difficulty. It also highlighted that not only does a placebo-controlled trial in surgery have to be ethically and scientifically acceptable but that it also must be a feasible course of action. The place of placebo-controlled surgical trials more generally is likely to be limited and require specific circumstances to be met. Suggested criteria are presented.

Trial registration number

The trial was assigned ISRCTN02328576 through http://controlled-trials.com/ in June 2006. The first patient was randomised to the pilot in July 2007.

Intra-articular morphine and bupivicaine for post-operative analgesia in anterior cruciate ligament reconstruction: a prospective randomised controlled trial

Anterior cruciate ligament reconstruction (ACLR) has the potential for significant post-operative pain. Conventional systemic opiate treatment may cause nausea and drowsiness, which may delay recovery. The use of intra-articular local anaesthesia has been shown to be effective. We wished to examine the additional effect of intra-articular morphine. This is a prospective, randomised, double-blind trial. Sixty patients were randomised to receive 20 ml 0.5% bupivicaine (group L, n = 30) or bupivicaine with 10 mg morphine (group M, n = 30) by intra-articular injection at the end of the operation. Visual analogue scores (VAS) were recorded before ACLR (expected pain) and repeated at 6 and 24 h after surgery. Time to first analgesic request and total systemic opiate and other analgesic use in the first 24 h was recorded. Pre-operative VAS measurements did not predict pain or analgesic use post-operatively. There were no significant differences between groups L and M with regard post-operative VAS or time to first analgesic request. Group M required less opiate analgesic post-operatively (oral morphine equivalent 50 mg for group L and 27 mg for group M, P < 0.007). There were no complications associated with the intra-articular analgesic. The simple addition of morphine to the intra-articular injection of bupivicaine gives a significant reduction in opiate analgesic requirement after ACLR.

Discovery of novel inhibitors of the ZipA/FtsZ complex by NMR fragment screening coupled with structure-based design

ZipA is a membrane anchored protein in Escherichia coli that interacts with FtsZ, a homolog of eukaryotic tubulins, forming a septal ring structure that mediates bacterial cell division. Thus, the ZipA/FtsZ protein-protein interaction is a potential target for an antibacterial agent. We report here an NMR-based fragment screening approach which identified several hits that bind to the C-terminal region of ZipA. The screen was performed by 1H-15N HSQC experiments on a library of 825 fragments that are small, lead-like, and highly soluble. Seven hits were identified, and the binding mode of the best one was revealed in the X-ray crystal structure. Similar to the ZipA/FtsZ contacts, the driving force in the binding of the small molecule ligands to ZipA is achieved through hydrophobic interactions. Analogs of this hit were also evaluated by NMR and X-ray crystal structures of these analogs with ZipA were obtained, providing structural information to help guide the medicinal chemistry efforts.

Rapid, automated screening method for enzymatic transformations using a robotic system and supercritical fluid chromatography

An automated screening method was developed for enzymatic transformations using a robotic system and rapid chiral supercritical fluid chromatography (SFC) analysis with a run time of 1.5 min. The method accelerates the enzyme selection process for screening biocatalysts, where a large number of enzymes are evaluated for activity and enantioselectivity. Kinetic resolution of secondary alcohols by enzymatic transesterification was used as a prototype for method development. The rapid automated method can be used effectively for screening enzymes and optimizing reaction conditions in biocatalysis.

Disturbance of pro-inflammatory cytokines in post-traumatic psychopathology

BACKGROUND

Post-traumatic psychopathology (PTP) is important to the orthopaedic surgeon as it may complicate the recovery from musculoskeletal injury. PTP is associated with a disturbance of the hypothalamic-pituitary-adrenal axis, and may lead to impaired healing. We have investigated the relationship between PTP and pro-inflammatory markers of the metabolic response to trauma.

MATERIALS AND METHODS

A prospective cohort study of 82 patients with musculoskeletal injuries, correlating development of psychopathology (measured by general health questionnaire) and pro-inflammatory markers (CRP, IL-6, sIL-6r, TNF-alpha) two and six months after their injury.

RESULTS

Psychological disturbance was found in 39% of patients at two months and 18% at six months. This disturbance was associated with significantly increased levels of IL-6 at two months and of sIL-6r and TNF-alpha at six months. CRP levels were not related to the development of PTP.

CONCLUSIONS

The relationship between PTP and disturbances of pro-inflammatory markers needs further exploration, but may explain in part the impaired functional recovery when musculoskeletal trauma is complicated by psychological disturbance.

Hydrophobic Acetal and Ketal Derivatives of Mannopeptimycin-α and Desmethylhexahydromannopeptimycin-α: Semisynthetic Glycopeptides with Potent Activity Against Gram-Positive Bacteria

The effect of introducing hydrophobic groups onto the disaccharide portion of the mannopeptimycins has been examined. Under acid-catalyzed conditions dimethyl acetals and ketals react on the terminal mannose of the disaccharide moiety of mannopeptimycin-alpha and the cyclohexylalanyl analogue 2. The preferentially formed monofunctionalized 4,6-acetals and -ketals display potent antibacterial activities against Gram-positive microorganisms, including MRSA, PRSP, and VRE pathogens.

Mechanism of action of the mannopeptimycins, a novel class of glycopeptide antibiotics active against vancomycin-resistant gram-positive bacteria

The naturally occurring mannopeptimycins (formerly AC98-1 through AC98-5) are a novel class of glycopeptide antibiotics that are active against a wide variety of gram-positive bacteria. The structures of the mannopeptimycins suggested that they might act by targeting cell wall biosynthesis, similar to other known glycopeptide antibiotics; but the fact that the mannopeptimycins retain activity against vancomycin-resistant organisms suggested that they might have a unique mode of action. By using a radioactive mannopeptimycin derivative bearing a photoactivation ligand, it was shown that mannopeptimycins interact with the membrane-bound cell wall precursor lipid II [C(55)-MurNAc-(peptide)-GlcNAc] and that this interaction is different from the binding of other lipid II-binding antibiotics such as vancomycin and mersacidin. The antimicrobial activities of several mannopeptimycin derivatives correlated with their affinities toward lipid II, suggesting that the inhibition of cell wall biosynthesis was primarily through lipid II binding. In addition, it was shown that mannopeptimycins bind to lipoteichoic acid in a rather nonspecific interaction, which might facilitate the accumulation of antibiotic on the bacterial cell surface.

Design and synthesis of indolo[2,3-a]quinolizin-7-one inhibitors of the ZipA–FtsZ interaction

The binding of FtsZ to ZipA is a potential target for antibacterial therapy. Based on a small molecule inhibitor of the ZipA-FtsZ interaction, a parallel synthesis of small molecules was initiated which targeted a key region of ZipA involved in FtsZ binding. The X-ray crystal structure of one of these molecules complexed with ZipA was solved. The structure revealed an unexpected binding mode, facilitated by desolvation of a loosely bound surface water.

Development of a fluorescence polarization assay to screen for inhibitors of the FtsZ/ZipA interaction

A fluorescence polarization competition assay has been developed to screen for inhibitors of the Escherichia coli FtsZ/ZipA protein-protein interaction. A previously published X-ray costructure demonstrated that a 17-amino-acid peptide, corresponding to FtsZ C-terminal residues 367-383 (FtsZ(367-383)), interacts with the C-terminal FtsZ binding domain of ZipA (ZipA(185-328)). Phage display was employed to identify a unique but related peptide which when further modified and labeled was shown to have a higher affinity to ZipA(185-328) than the FtsZ(367-383) peptide and binds to the same site. This peptide had a six fold increase in fluorescence polarization upon binding to ZipA(185-328) compared to a two fold increase for the FtsZ(367-383) fluorophore. As a result, assay parameters using the phage display peptide were further optimized and adapted for the high-throughput screen. A high-throughput screen of 250,000 compounds identified 29 hits with inhibition equal to or greater than 30% at 50 microg/ml. An X-ray costructure of a promising small molecule in this library complexed with ZipA(185-328) (KI=12 microM) revealed that the compound binds to the same hydrophobic pocket as the FtsZ(367-383) peptide.

Structure-based design of carboxybiphenylindole inhibitors of the ZipA–FtsZ interaction

Structural features of two weak inhibitors of the ZipA-FtsZ protein-protein interaction which were found to bind to overlapping but different areas of the key binding site were combined in one new series of carboxybiphenyl-indoles with improved inhibitory activity.

C-reactive protein and interleukin 6 receptor in post-traumatic stress disorder: a pilot study

BACKGROUND

it has been reported that psychological stress in humans is associated with a derangement of biological homeostasis. This pilot study aimed to examine the inflammatory response to post-traumatic stress disorder (PTSD) through measurements of the serum levels of the receptor to interleukin 6 (sIL-6r) and C-reactive protein (CRP), in relation to measures of psychological disturbance.

METHODS

15 patients with established PTSD and eight control patients with musculoskeletal injuries were studied at least three months after their index trauma. All completed revised impact of events scale (RIES), Davidson's trauma scale (DTS) and the general health questionnaire (GHQ), and gave blood samples that were assayed for CRP and sIL-6r. Statistical analysis was by the Mann-Whitney U-Wilcoxon rank sum tests.

RESULTS

positive relationships were found between sIL-6r and the RIES intrusion score (P=0.026), and between CRP and DTS intrusion scores (P=0.016), GHQ depression (P=0.028), and RIES intrusion (P=0.044) in the case group.

DISCUSSION

we have demonstrated a relationship between post-traumatic psychological and biological disturbance, which provides the basis for further research on the effects of psychological disturbance on physical recovery after injury.

Urinary soluble IL-6 receptor levels after cardiopulmonary bypass

To investigate the possible role of soluble interleukin 6 receptor (sIL-6r) in the inflammatory response to cardiopulmonary bypass (CPB) with extracorporeal circulation (ECC), we examined the levels of sIL-6r in the urine of 50 patients undergoing coronary artery bypass surgery. The presence of sIL-6r in urine was confirmed in these patients, with levels rising from 6 pg/ml preoperatively to 19.5 pg/ml at 6 h and 41 pg/ml at 24 h after the start of cardiopulmonary bypass. Cardiopulmonary bypass leads to a rise in sIL-6r in urine that has not returned to normal after 24 h, suggesting a role for sIL-6r and IL-6 in the inflammatory response to such surgery. Determination of cytokine receptor presence in urine offers a non-invasive approach to the monitoring of the immune and inflammatory response to the stress of surgical and traumatic injury.

Bilateral fractured clavicles--a pair of cases

The authors present two cases of bilateral fractured clavicles, both resulting from direct trauma to both shoulders. In both cases, the fractures healed uneventfully with non-operative treatment.

Removal of the subchondral plate in acetabular preparation

Retention of the subchondral plate during acetabular preparation in total hip replacement is believed to be an important part of modern cementing techniques. We have constructed a two-dimensional finite element analysis to assess the effect of retention and removal of this relatively stiff structure. The finite element analysis demonstrates increased stiffness and stress concentrations at the bone-cement interface that may have an adverse effect. Although further study is required, it may be that subchondral bone retention is not advantageous.

Abductor weakness and stresses around acetabular components of total hip arthroplasty: a finite element analysis

Abductor weakness, and the resulting Trendelenburg gait, after total hip arthroplasty is believed to be associated with a poor long-term outcome. We have constructed a two-dimensional finite element analysis using load cases to mimic this abductor weakness. The finite element analysis demonstrates slightly increased stresses, particularly at the bone-cement interface in the DeLee-Charnley zone I, which does not seem sufficient to explain the adverse effect of abductor weakness.

Ring-Chain Tautomerism of the 1,4-Oxathiane S,S-Dioxide Anion

The ring-chain tautomer of the α-sulfonyl anion of 1,4-oxathiane S,S-dioxide can be trapped by addition of alkoxides to the vinyl sulfone; the scope of this reaction is explored.

Who actually does orthopaedic operating?

Recent correspondence in the British Medical Journal suggested that up to 80% of orthopaedic trauma surgery is carried out by unsupervised trainees. We examined our own experience by gathering theatre computer system data over a six month period and case note verification. Unsupervised trainees carried out 48% of the trauma surgery, but only 13% of the elective surgery. Case sheet review demonstrated that the computer system over-attributed operating to the senior surgeon, and under-recorded the presence of unscrubbed consultants. Supervision of trainees is important for both training and service provision, and needs to be tailored to the needs of individual trainees, but we were disappointed with our results. Theatre computer records may not be accurate enough to allow assessment of the level of supervision.

Screening times with image intensifier in orthopaedic trauma surgery

Image intensifier technology has been of great benefit to orthopaedic, but not a benign aid. We have examined the image intensifier screening times for trainees and consultants over a seven month period. Consultants did not always have shorter screening times, and there were no differences between radiographers, Surgeons of all grades should depend more upon anatomical knowledge and spatial orientation, and less upon the image intensifier.

Infection associated with the use of allograft bone from the north east Scotland Bone Bank

To assess the rate of infection associated with use of banked allograft bone, the case records of patients receiving banked bone over one year were reviewed. The notes of patients undergoing autografting procedures during the same period were reviewed as controls. Eighty-two patients received 98 banked allograft femoral heads and there were 10 proven infections (12.2%). Fifty-seven patients had autograft procedures, with two cases of infection (3.5%). The results of bacteriological surveillance of grafts harvested during the same period were analysed; there was a discard rate due to bacterial contamination of 1.3%, and two patients received three contaminated grafts, one of these patients suffering a postoperative infection. The failure rate of procedures was 50% where there was postoperative infection and 4.2% where there was none. Procedures using banked allograft bone have a substantial infection risk, and this is associated with a much higher rate of failure of the procedure. Prospective audit of allograft use should be applied to reduce this risk.

Differing injury patterns in snowboarding and alpine skiing

This is a study of all people presenting to ski patrollers with ski and snowboard injuries during the 1995 season. There were 476 casualties of whom 396 were skiers and 57 were snowboarders. Information was collected retrospectively on the mechanism, region and injury, and also personal details of the casualties. The information was compared with the numbers of ski and snowboard injuries for the 1994 season. Injuries due to snowboarding increased in frequency, from 4 per cent in 1994 to 11 per cent in 1995. Snowboarders were younger, predominantly male, and were more often beginners than were skiers. They most commonly sustained ligament strains, dislocations and fractures, with the hand and forearm and shoulder most affected. Skiers sustained more ligament strains and soft tissue bruising, particularly of the knee and thumb. Snowboarders sustain a different pattern of injuries compared with skiers, and this has important implications for preventing accidents in the instruction of novices.

Gastric lymphoma in Grampian Region: presentation, treatment and outcome

Forty cases of gastric lymphoma presenting in Grampian Region (1974-91) were reviewed to examine the effects of changing ideas in the fields of chemotherapy, gastric surgery and diagnostic techniques, as well as the impact of Helicobacter pylori. Presentation was non-specific, and the diagnosis was made pre-operatively in only 12 cases. Survival was related to tumour size, staging (Ann Arbor), and grade, with a crude 5-year survival of 49%. Helicobacter pylori was found in all specimens reviewed. Patients who underwent "potentially curative' surgery followed by adjuvant therapy had the best survival (85% at 5 years). There remains a need for larger studies to define the best treatment for this uncommon condition.