A practical approach to screening for carbapenemase-producing Enterobacterales- views of a group of multidisciplinary experts from English hospitals

INTRODUCTION

Carbapenemase-producing Enterobacterales (CPE) are an important public health threat, with costly operational and economic consequences for NHS Integrated Care Systems and NHS Trusts. UK Health Security Agency guidelines recommend that Trusts use locally developed risk assessments to accurately identify high-risk individuals for screening, and implement the most appropriate method of testing, but this presents many challenges.

METHODS

A convenience sample of cross-specialty experts from across England met to discuss the barriers and practical solutions to implementing UK Health Security Agency framework into operational and clinical workflows. The group derived responses to six key questions that are frequently asked about screening for CPE.

KEY FINDINGS

Four patient groups were identified for CPE screening: high-risk unplanned admissions, high-risk elective admissions, patients in high-risk units, and known positive contacts. Rapid molecular testing is a preferred screening method for some of these settings, offering faster turnaround times and more accurate results than culture-based testing. It is important to stimulate action now, as several lessons can be learnt from screening during the COVID-19 pandemic, as well as from CPE outbreaks.

CONCLUSION

Further decisive and instructive information is needed to establish CPE screening protocols based on local epidemiology and risk factors. Local management should continually evaluate local epidemiology, analysing data and undertaking frequent prevalence studies to understand risks, and prepare resources- such as upscaled screening- to prevent increasing prevalence, clusters or outbreaks. Rapid molecular-based methods will be a crucial part of these considerations, as they can reduce unnecessary isolation and opportunity costs.

965 Complication Rates in Operatively Managed Ankle Fracture/Dislocations - The Effect of Pre-Reduction Imaging and Compliance with BOAST 12 Guidance

Aim

The BOAST-12 guidelines for the management of ankle fractures aims to optimise functional recovery and reduce complications. They advise against having radiographs prior to urgent reduction of clinically deformed ankles as it could cause an unacceptable delay to subsequent management. Our study aimed to assess the effect of time to acceptable reduction on the risk of complications and time to definitive reduction.

Method

This was a retrospective observational study of patients with ankle fracture-dislocations between 2013 to 2017 at the Northern General Hospital’s Emergency Department (ED). Information collected from 2 patient groups (with and without pre-reduction radiographs), included patient demographics, time to accepted reduction, number of manipulations, operations, and subsequent complications.

Results

242 patients were identified. Time from arrival in ED to acceptable reduction was significantly longer in patients with pre-reduction radiographs versus patients without (184.5 vs 82 minutes, p < 0.00), but did not increase the overall risk of complications (p = 0.62). Pre-reduction radiographs were associated with insignificantly higher rates of post-traumatic osteoarthritis (p = 0.17) and slightly longer wait time for definitive intervention (1 vs 2 days, p = 0.72). However, this had no relationship with the number of manipulations (p = 0.53).

Conclusions

The use of pre-reduction radiographs significantly increased time to acceptable reduction of ankle fracture-dislocations. However, this was not associated with increased risk of complications or time to definitive management.

Response to Letter to the editor: Acute Medicine Journal

Editor- Thank you for giving us the opportunity to respond to the letter received regarding the Joint Royal College of Physicians Training Board (JRCPTB) curriculum for Acute Internal Medicine (AIM) that has previously been circulated for comment and consideration of implementation in August 2022. Dr Williamson is correct in asserting that the proposed curriculum hopes to produce doctors with generic professional and specialty specific capabilities needed to manage patients presenting with a wide range of medical symptoms and conditions. It does aim to produce a workforce that reflects the current trends of increasing patient attendances to both primary care and emergency departments- one that has a high level of diagnostic reasoning, the ability to manage uncertainty, deal with co-morbidities and recognise when specialty input is required in a variety of settings, including ambulatory and critical care.

Trauma to the medial ray of the foot: A classification of patterns of injury and their management

AIMS

Fractures and dislocations of the midfoot are relatively uncommon but can be life changing injuries. Within the literature, there has been scant specific reference to the identification and management of medial ray injuries in midfoot trauma. Moreover, it is appreciated that these injuries are associated with poor outcomes. We aim to clearly define these injury characteristics and demonstrate fixation techniques.

PATIENTS AND METHODS

A retrospective review of the case notes and imaging was conducted for operatively treated midfoot injuries between January 2013 and January 2018.

RESULTS

161 patients were identified, 31 of these with imaging and operative diagnosis suggestive of medial ray injury. Studying these 31 injuries revealed five patterns of injury.

CONCLUSION

When treating midfoot trauma, it is important to fully understand the injury pattern as this dictates the principles and techniques of fixation. Identification and knowledge of these five injury patterns will aid surgeons in future management of these injuries and may improve treatment outcomes.

Abstract P4-08-17: Expression score (Escore) for the prediction of likelihood of recurrence of DCIS

Background: Ductal carcinoma in situ (DCIS) accounts for at least 20% of breast cancers. Factors associated with recurrence of DCIS or progression to invasive carcinoma are not well delineated. The goals of the current study were to profile the epithelial cells using the GE Cell DIVE™ immuno-fluorescent based analyses. This was coupled with semi-automated algorithms to characterize the inter-relationships between cell populations and likelihood of recurrence.

Patients and Methods: A TMA-based (total 8 TMAs) cohort of cases of DCIS with and without recurrence was obtained from Oxford University. Recurrence in this cohort was defined as ipsilateral DCIS, ipsilateral invasive, contralateral invasive and metastatic. Analysis for 31 epithelial markers (HER4, CK56, ABCG2, PTEN, S6, CKAE1, PR, ER, NaKATPase, CK19, ALDH1, CK PCK26, cMET, CD44v6, HER2, CDCP1, p53, CK15, COX2, VEGFR2, ABCb1, HTF9C, CD10, MRP4, CEACAM5, EGFR, p21, MRP5, SLC7A5, Ki67, DAPI) was performed on a single FFPE TMA section containing cases of DCIS. Briefly, FFPE sections from TMAs containing DCIS were sequentially (cyclically) stained for the markers. Each cycle entailed staining with 2-3 markers followed by imaging, dye inactivation, and re-staining. DAPI was used for nuclear demarcation and for registration of the images, while S6, pan-cadherin, Na+K+ATPase and pan-cytokeratin were used for epithelial segmentation. K-means clustering followed regression analysis was performed to identify inter-relationships between markers and association with likelihood of recurrence. Log-rank analysis was performed and the relapse-free survival data depicted using Kaplan Meier plots. Escore was developed by logistic regression model, classification model on recurrence

Results: Filtering of the expression analysis by the quality, specificity, compartment localization and fields entirely composed of DCIS, in addition to availability of clinical data resulted final analysis of 31 markers in 67 cases. Correlation analyses were performed on each of the markers to identify markers that were significantly correlated in univariate analysis. K-means cluster analysis was performed using a set of 4 markers (ER, HER2, SLC7A5 and cMET) to identify 6 clusters. High cMET (cluster 1; low HER2 and SLC7A5) and High ER (low cMET, HER2, SLC7A5; Cluster 5) were associated with low risk of recurrence (p values 0.014 and <0.0001). In contrast, Cluster 2 (High HER2, high SLC7A5, low ER) and Cluster 3 (High HER2, low ER, SLC7A5and cMET) were associated with increased risk of recurrence (P values 0.038 and 0.076). A regression analysis based algorithm was developed using these markers to calculate a numerical score which could predict likelihood of recurrence. As depicted in the KM plots, the HR for recurrence increases significantly (P-value 2.4E-05; p=0.02 with LOOCV) with increase in expression score (Escore).

Conclusions: We describe the development of an Escore using expression 4 markers to predict likelihood of recurrence. Additional ongoing studies will seek to validate the utility of the Escore in predicting likelihood of recurrence of DCIS and development of invasive carcinomas and comparison with other scoring systems.

Citation Format: Badve SS, Cho S, Gokmen-Polar Y, Zavodszky M, Sui Y, Chadwick C, Tan PH, Gerdes M, Harris AL, Ginty F. Expression score (Escore) for the prediction of likelihood of recurrence of DCIS [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-17.

A new and reliable classification system for fractures of the navicular and associated injuries to the midfoot

AIMS

Fractures of the navicular can occur in isolation but, owing to the intimate anatomical and biomechanical relationships, are often associated with other injuries to the neighbouring bones and joints in the foot. As a result, they can lead to long-term morbidity and poor function. Our aim in this study was to identify patterns of injury in a new classification system of traumatic fractures of the navicular, with consideration being given to the commonly associated injuries to the midfoot.

PATIENTS AND METHODS

We undertook a retrospective review of 285 consecutive patients presenting over an eight- year period with a fracture of the navicular. Five common patterns of injury were identified and classified according to the radiological features. Type 1 fractures are dorsal avulsion injuries related to the capsule of the talonavicular joint. Type 2 fractures are isolated avulsion injuries to the tuberosity of the navicular. Type 3 fractures are a variant of tarsometatarsal fracture/dislocations creating instability of the medial ray. Type 4 fractures involve the body of the navicular with no associated injury to the lateral column and type 5 fractures occur in conjunction with disruption of the midtarsal joint with crushing of the medial or lateral, or both, columns of the foot.

RESULTS

In order to test the reliability and reproducibility of this new classification, a cohort of 30 patients with a fracture of the navicular were classified by six independent assessors at two separate times, six months apart. Interobserver reliability and intraobserver reproducibility both had substantial agreement, with kappa values of 0.80 and 0.72, respectively.

CONCLUSION

We propose a logical, all-inclusive, and mutually exclusive classification system for fractures of the navicular that gives associated injuries involving the lateral column due consideration. We have shown that this system is reliable and reproducible and have described the rationale for the subsequent treatment of each type. Cite this article: Bone Joint J 2018;100-B:176-82.

Symptomatic treatment or cast immobilisation for avulsion fractures of the base of the fifth metatarsal: a prospective, randomised, single-blinded non-inferiority controlled trial

AIMS

The purpose of this study was to compare symptomatic treatment of a fracture of the base of the fifth metatarsal with immobilisation in a cast. Our null hypothesis was that immobilisation gave better patient reported outcome measures (PROMs). The alternative hypothesis was that symptomatic treatment was not inferior.

PATIENTS AND METHODS

A total of 60 patients were randomised to receive four weeks of treatment, 36 in a double elasticated bandage (symptomatic treatment group) and 24 in a below-knee walking cast (immobilisation group). The primary outcome measure used was the validated Visual Analogue Scale Foot and Ankle (VAS-FA) Score. Data were analysed by a clinician, blinded to the form of treatment, at presentation and at four weeks, three months and six months after injury. Loss to follow-up was 43% at six months. Multiple imputations missing data analysis was performed.

RESULTS

At four weeks and six months, symptomatic treatment proved non-inferior in terms of primary outcome.

TAKE HOME MESSAGE

Immobilisation is no better than symptomatic treatment in the management of a fracture of the base of the fifth metatarsal when judged by PROMs. Significant loss to follow-up with this injury could be expected in longer term. Cite this article: Bone Joint J 2016;98-B:806-11.

Long-term follow-up of flexor digitorum longus transfer and calcaneal osteotomy for stage II posterior tibial tendon dysfunction

Flexor digitorum longus transfer and medial displacement calcaneal osteotomy is a well-recognised form of treatment for stage II posterior tibial tendon dysfunction. Although excellent short- and medium-term results have been reported, the long-term outcome is unknown. We reviewed the clinical outcome of 31 patients with a symptomatic flexible flat-foot deformity who underwent this procedure between 1994 and 1996. There were 21 women and ten men with a mean age of 54.3 years (42 to 70). The mean follow-up was 15.2 years (11.4 to 16.5). All scores improved significantly (p < 0.001). The mean American Orthopedic Foot and Ankle Society (AOFAS) score improved from 48.4 pre-operatively to 90.3 (54 to 100) at the final follow-up. The mean pain component improved from 12.3 to 35.2 (20 to 40). The mean function score improved from 35.2 to 45.6 (30 to 50). The mean visual analogue score for pain improved from 7.3 to 1.3 (0 to 6). The mean Short Form-36 physical component score was 40.6 (sd 8.9), and this showed a significant correlation with the mean AOFAS score (r = 0.68, p = 0.005). A total of 27 patients (87%) were pain free and functioning well at the final follow-up. We believe that flexor digitorum longus transfer and calcaneal osteotomy provides long-term pain relief and satisfactory function in the treatment of stage II posterior tibial tendon dysfunction.

Deferasirox (ICL670A) effectively inhibits oesophageal cancer growth in vitro and in vivo

BACKGROUND AND PURPOSE

Growing evidence implicates iron in the aetiology of gastrointestinal cancer. Furthermore, studies demonstrate that iron chelators possess potent anti-tumour activity, although whether iron chelators show activity against oesophageal cancer is not known.

EXPERIMENTAL APPROACH

The effect of the iron chelators, deferoxamine (DFO) and deferasirox, on cellular iron metabolism, viability and proliferation was assessed in two oesophageal adenocarcinoma cell lines, OE33 and OE19, and the squamous oesophageal cell line, OE21. A murine xenograft model was employed to assess the effect of deferasirox on oesophageal tumour burden. The ability of chelators to overcome chemoresistance and to enhance the efficacy of standard chemotherapeutic agents (cisplatin, fluorouracil and epirubicin) was also assessed.

KEY RESULTS

Deferasirox and DFO effectively inhibited cellular iron acquisition and promoted intracellular iron mobilization. The resulting reduction in cellular iron levels was reflected by increased transferrin receptor 1 expression and reduced cellular viability and proliferation. Treating oesophageal tumour cell lines with an iron chelator in addition to a standard chemotherapeutic agent resulted in a reduction in cellular viability and proliferation compared with the chemotherapeutic agent alone. Both DFO and deferasirox were able to overcome cisplatin resistance. Furthermore, in human xenograft models, deferasirox was able to significantly suppress tumour growth, which was associated with decreased tumour iron levels.

CONCLUSIONS AND IMPLICATIONS

The clinically established iron chelators, DFO and deferasirox, effectively deplete iron from oesophageal tumour cells, resulting in growth suppression. These data provide a platform for assessing the utility of these chelators in the treatment of oesophageal cancer patients.

Guidelines for the control of glycopeptide-resistant enterococci in hospitals

The increase since the mid 1980s in glycopeptide resistant enterococci (GRE) raised concerns about the limited options for antimicrobial therapy, the implications for ever-increasing numbers of immunocompromised hospitalised patients, and fuelled fears, now realised, for the transfer of glycopeptide resistance to more pathogenic bacteria, such as Staphylococcus aureus. These issues underlined the need for guidelines for the emergence and control of GRE in the hospital setting. This Hospital Infection Society (HIS) and Infection Control Nurses Association (ICNA) working party report reviews the literature relating to GRE prevention and control. It provides guidance on microbiological investigation, treatment and management, including antimicrobial prescribing and infection control measures. Evidence identified to support recommendations has been categorized. A risk assessment approach is recommended and areas for research and development identified.

Autologous blood pleurodesis for pneumothorax complicating graft-versus-host disease-related bronchiolitis obliterans

Bronchiolitis obliterans (BO) is a manifestation of chronic graft-versus-host disease (GVHD) after allogeneic haemopoietic stem cell transplantation. Complications associated with this include persistent air-leak syndromes such as pneumothorax. Many methods have been described for treating this condition, both surgical and nonsurgical. We describe an 8-year-old boy with acute lymphoblastic leukaemia complicated by chronic GVHD-related BO, and subsequent pneumothorax with persistent air leak, who was treated successfully with autologous blood pleurodesis.

Management of acute cholecystitis in UK hospitals: time for a change

Early cholecystectomy for patients with acute cholecystitis is safe, cost effective, and leads to less time off work compared with delayed surgery. This study was designed to assess current practice in the management of acute cholecystitis in the UK. A postal questionnaire was sent to 440 consultant general surgeons to ascertain their current management of patients with acute cholecystitis. Replies were received from 308 consultants who were involved in treating patients with acute cholecystitis of whom 18 transferred these patients on to another team for further management the day after admission. Thirty two consultants (11%) routinely treated patients by early cholecystectomy, with limiting factors stated to be the availability of surgical staff, theatre space, and radiological investigations. The remaining consultants (n = 258) routinely manage their patients conservatively with intravenous antibiotics and allow the inflammation to resolve before undertaking cholecystectomy at a later date. Indications for undertaking early cholecystectomy during the first admission by this latter group included the presence of spreading peritonitis due to bile leak, empyema, and unexpected space on theatre list. The commonest method for both elective and early cholecystectomy is laparoscopic, but the percentage of consultants using an open method rises from 8% in the elective situation to 47% for urgent early cholecystectomy. Despite evidence which strongly advocates early cholecystectomy, this practice is routinely carried out by only 11% of consultants in the UK at present.

Acute cholecystitis--room for improvement?

AIMS

A recent survey of UK general surgeons showed that almost 90% prefer to manage patients with acute cholecystitis by initial conservative management and delayed cholecystectomy (DC). The aim of this study was to assess the effectiveness of this management policy in a large university hospital.

PATIENTS AND METHODS

All patients admitted with acute cholecystitis between January 1997 and June 1999 who went on to have a cholecystectomy were identified. Patients were required to have right upper quadrant pain for > 12 h, a raised white cell count and findings consistent with acute cholecystitis on ultrasound to be included in the study.

RESULTS

109 patients were admitted with acute cholecystitis (76 female, 33 male) with a median age of 62 years (range, 22-88 years). Conservative management failed in 16 patients (14.7%) who underwent emergency cholecystectomy due to continuing symptoms (9), empyema (4) and peritonitis (3). Symptoms settled in 93 patients and delayed cholecystectomy was performed without further problems in 66 (60.6%). 27 patients were re-admitted with further symptoms before their elective surgery and, of these, 3 were admitted for a third time before surgical intervention. Ten of the 30 re-admission episodes (33%) occurred within 3 weeks of discharge but 15 (56%) occurred more than 2 months after discharge. Elective surgery was undertaken at a median of 10 weeks post-discharge with 67% of operations occurring within 3 months. Mean total hospital stay (days) +/- SEM, for the three groups were: emergency surgery group, 10.21 +/- 0.85; uncomplicated DC group, 12.48 +/- 0.37; re-admitted group, 14.75 +/- 0.71.

CONCLUSIONS

The policy of conservative management and DC was successful in 60.6% of cases but 14.7% of patients required emergency surgery and 24.8% were re-admitted prior to elective surgery with a resultant increase in total hospital stay. Performing elective surgery within 2 months of discharge in all cases would have reduced the re-admission rate by 56% and this along with the increased use of early cholecystectomy during the first admission are areas where the treatment of acute cholecystitis could be significantly improved.

Tanning salon exposure and molecular alterations

BACKGROUND

Human studies of the short-term cellular effects of tanning salon exposures are lacking. Findings of such studies may prove extremely helpful in educating consumers considering or currently attending tanning salons.

OBJECTIVE

Our purpose was to determine whether tanning salon exposure causes DNA alterations and p53 protein expression in epidermal keratinocytes and/or circulating peripheral lymphocytes.

METHODS

Eleven subjects received 10 full-body tanning salon exposures over a 2-week period. UV-induced DNA cyclobutane pyrimidine dimers and p53 protein expression were examined, comparing pretreatment peripheral blood lymphocytes and epidermal biopsy specimens with analogous specimens obtained after the 10 tanning salon exposures.

RESULTS

Cyclobutane pyrimidine dimers in DNA and p53 protein expression were detected in epidermal keratinocytes, but were absent in lymphocytes.

CONCLUSION

Similar to outdoor sun exposure, short-term recreational tanning salon exposure causes molecular alterations believed essential in the development of skin cancer.

Current practice in the management of acute cholecystitis

AIMS: Several recent papers have advocated emergency cholecystectomy for patients with acute cholecystitis, stating that it is safe, cost effective and leads to less time off work. This study was designed to assess current practice in the management of acute cholecystitis in the UK. METHODS: A postal questionnaire was sent to 357 consultant surgeons who were thought to be involved in a general surgical on-call rota, to ascertain their current management of patients with acute cholecystitis. Replies were received from 250 consultants (70 per cent) of whom 242 (68 per cent) were involved in a general surgical take. Sixteen of these consultants, however, handed their patients with acute cholecystitis on to a different team the following day for further management. RESULTS: Twenty-seven consultants (12 per cent) routinely treat their patients by emergency cholecystectomy whenever possible, with 24 stating that they would do this within 72 h. Limiting factors to this practice were stated to be availability of surgical staff (15), theatre space (nine) and radiological investigations (four). The remaining consultants (n = 199) routinely manage their patients conservatively initially and providing they settle, either (1) book directly for cholecystectomy (n = 94, 47 per cent), (2) reassess as an outpatient (n = 65, 33 per cent), (3) either of above (n = 21; 11 per cent) or (4) refer on to a colleague (n = 19, 10 per cent). The commonest indications for acute cholecystectomy stated by consultants whose initial treatment policy is conservative are spreading peritonitis due to bile leak (93 per cent), empyema (89 per cent), unexpected space on a theatre list (28 per cent) and failure of an acute episode to settle (21 per cent). The laparoscopic method is the commonest for both elective and emergency cholecystectomy, but the percentage of consultants using an open method rises dramatically from 9 per cent in the elective situation to 48 per cent for emergency cholecystectomy. CONCLUSIONS: Despite evidence to support the increased use of emergency cholecystectomy, this practice is routinely carried out by only 12 per cent of consultants. However, of the consultants who treat their patients conservatively, 28 per cent are prepared to undertake emergency cholecystectomy if an unexpected space appears on the theatre list.

Vancomycin-resistant enterococci: implications for infection control

The incidence of vancomycin-resistant enterococci (VRE) infection is increasing. Immunosuppressed individuals are particularly vulnerable to infection with VRE. Strict attention to infection control measures is important in preventing the spread of multiresistant organisms.

Enzyme therapy of xeroderma pigmentosum: safety and efficacy testing of T4N5 liposome lotion containing a prokaryotic DNA repair enzyme

Xeroderma pigmentosum (XP) is a rare genetic disease in which patients are defective in DNA repair and are extremely sensitive to solar UV radiation exposure. A new treatment approach was tested in these patients, in which a prokaryotic DNA repair enzyme specific for UV-induced DNA damage was delivered into the skin by means of topically applied liposomes to supplement the deficient activity. Acute and chronic safety testing in both mice and humans showed neither adverse reactions nor significant changes in serum chemistry or in skin histology. The skin of XP patients treated with the DNA repair liposomes had fewer cyclobutylpyrimidine dimers in DNA and showed less erythema than did control sites. The results encourage further clinical testing of this new enzyme therapy approach.

Apoptosis, intrinsic radiosensitivity and prediction of radiotherapy response in cervical carcinoma

Apoptosis is an important mechanism of cell death in tumours and it is seen both prior to and following radiotherapy. In this study patients with proven carcinoma of the cervix had measurement made of the percentage of apoptotic cells (apoptotic index or AI) in pre-therapy biopsies. Measurements of intrinsic radiosensitivity (SF2), already shown to be a predictor of outcome, had previously been made on the same pre-therapy biopsies. Mitotic index (MI) and Ki-67 antigen staining were also recorded as markers for proliferation. Patients were divided into those with an AI above or below the median and in general increasing apoptosis was associated with poor prognosis. The 5-year survival rate for tumours with an AI below the median was 79% and was significantly greater than the rate of 47% for those with an AI above the median (p = 0.003). There was also a significantly increased 5-year local recurrence-free rate for patients with an AI below the median compared with those with an AI above the median (79 versus 61%, p = 0.012). In addition, AI and SF2 acted as independent prognostic indicators. Patients with both an SF2 and AI value above the median did badly (25% 5-year survival, 46% local control) compared with those with an SF2 and AI below the median (80% 5-year survival, 100% local control). Apoptosis showed correlation with MI (n = 66, r = 0.34, p = 0.002) and cell staining for the Ki-67 antigen (n = 57, r = 0.25, p = 0.03), but neither MI nor Ki-67 were related to patient outcome. This suggests that while apoptosis may be a reflection of tumour proliferation this cannot in itself explain the ability of apoptosis to predict clinical outcome for this series of patients. The study raises the possibility of AI and SF2 being used together as predictors of tumour response to radiotherapy.

Cryo-EM of the native structure of the calcium release channel/ryanodine receptor from sarcoplasmic reticulum

The native structure of the calcium release channel (ryanodine receptor) from rabbit skeletal muscle has been analyzed in two dimensions from electron micrographs of frozen hydrated specimens. Within a resolution of 3.0 nm there is excellent agreement between the structure as seen in vitreous water and in negative stained specimens. Features seen in the three-dimensional reconstruction of the negatively stained channel can be identified in the projection of the unstained receptor.

The MRC Multicentre Study of Cognitive Function and Ageing: a EURODEM incidence study in progress

The purpose of this paper is to describe the design and methodology of this multicentre study of cognitive function and ageing, which is currently funded by the Medical Research Council (MRC) and the Department of Health for a period of 5 years. The study is designed to estimate and compare the prevalence and incidence of dementia in five centres in the United Kingdom, to examine the natural history of cognitive decline and dementia in the population and to evaluate the degree of disability associated with any decline. This will be achieved by the examination, twice, of the cognitive function of individuals aged 65 and over, with an interval of 2 years between the examinations. A 20% subsample, taken across the full range of cognitive function will be reviewed annually in more detail to chart the level of cognitive function and to ascertain a diagnosis of dementia. This represents the first systematic examination of different populations using a common methodology in the United Kingdom.

Molecular cloning and characterization of the ryanodine receptor/junctional channel complex cDNA from skeletal muscle sarcoplasmic reticulum

Major progress has been made in elucidating the calcium release mechanism involved in excitation-contraction coupling. The ryanodine receptor of sarcoplasmic reticulum has been isolated and found to be morphologically identical to the foot structure, which is involved in the junctional association of terminal cisternae with the transverse tubule. The foot structure also contains the calcium release channel itself. For this reason, we refer to the foot structure as the junctional channel complex (JCC). The JCC consists of an oligomer of a single high molecular weight protein. Although progress has been made in characterizing important aspects of the structure and function of the JCC, further understanding of the JCC protein subunit awaits the molecular cloning of the JCC. We report on the isolation of cDNA clones encoding portions of the JCC from rabbit fast-twitch skeletal muscle and its tissue distribution and expression. The large size and lack of solubility of the JCC protein posed particular challenges to cloning this molecule. Among these was the necessity to develop techniques for partially digesting the JCC protein subunit with endoproteases in the presence of detergent. With this approach we obtained partial amino acid sequences from regions of the JCC and designed oligonucleotide primers and probes to synthesize and screen cDNA libraries. The rabbit skeletal muscle JCC mRNA encodes an approximately 16-kilobase mRNA present in skeletal, heart, and aortic smooth muscle, as determined by RNA blot analysis with a 700-base-pair cDNA probe. Whereas the JCC mRNA appears to be relatively abundant in adult rabbit fast-twitch skeletal muscle, it is much less abundant in heart and smooth muscle. The JCC mRNA in BC3H1 (a myoblast cell line) is reversibly regulated by growth factors in a manner similar to muscle-specific contractile protein genes.

Availability of treatment and diagnostic labelling

A sample of pre-1967 case records with a hospital diagnosis of schizoaffective disorder were presented for rediagnosis to members of the present staff of the Institute of Psychiatry/Maudsley Hospital. The raters were asked to make a diagnostic choice of either schizophrenia or schizoaffective disorder or affective disorder and indicate how useful they would consider certain treatments for the present episode and for the long term. There was a significant trend in diagnosis to affective disorder but this trend was not correlated with the usefulness of certain treatments, e.g. lithium, a drug which had not been in use before 1967.

Characterization of the junctional face membrane from terminal cisternae of sarcoplasmic reticulum

We have recently described a preparation of junctional terminal cisternae (JTC) from fast skeletal muscle of rabbit hind leg. The fraction differs from other heavy sarcoplasmic reticulum (SR) fractions in that it contains a substantial amount of junctional face membrane (JFM) (15-20% of the membrane) with morphologically well-defined junctional feet structures. In common with other heavy SR preparations, it contains predominantly the calcium pump membrane (80-85% of the membrane) and compartmental contents (CC), consisting mainly of calcium-binding protein (calsequestrin). In this study, a modified procedure for the preparation of JTC from frozen rabbit back muscle is described. The yield is substantially greater (threefold per weight of muscle), yet retaining characteristics similar to JTC from fresh hind leg muscles. Methodology has been developed for the disassembly of the JTC. This is achieved by selectively extracting the calcium pump membrane with 0.5% Triton X-100 in the presence of 1 mM CaCl2 to yield a complex of JFM with CC. The CC are then solubilized in the presence of EDTA to yield JFM. This fraction contains unidirectionally aligned junctional feet structures protruding from the cytoplasmic face of the membrane with repeat spacings comparable to that observed in JTC. The JFM contains 0.16 mumol phosphorus (lipid) per milligram protein. Characteristic proteins include 340 and 79-kD bands, a doublet at 28 kD, and a component that migrates somewhat slower than or equivalent to the calcium pump protein. Approximately 10% of the calcium-binding protein remains bound to the JFM after EDTA extraction, indicating the presence of a specific binding component in the JFM. The JFM, which is involved in junctional association with transverse tubule and likely in the Ca2+ release process in excitation-contraction coupling, is now available in the test tube.

Monomers of the Neurospora plasma membrane H+-ATPase catalyze efficient proton translocation

Liposomes prepared by sonication of asolectin were fractionated by glycerol density gradient centrifugation, and the small liposomes contained in the upper region of the gradients were used for reconstitution of purified, radiolabeled Neurospora plasma membrane H+-ATPase molecules by our previously published procedures. The reconstituted liposomes were then subjected to two additional rounds of glycerol density gradient centrifugation, which separate the H+-ATPase-bearing proteoliposomes from ATPase-free liposomes by virtue of their greater density. The isolated H+-ATPase-bearing proteoliposomes in two such preparations exhibited a specific H+-ATPase activity of about 11 mumol of Pi liberated/mg of protein/min, which was approximately doubled in the presence of nigericin plus K+, indicating that a large percentage of the H+-ATPase molecules in both preparations were capable of generating a transmembrane protonic potential difference sufficient to impede further proton translocation. Importantly, quantitation of the number of 105,000-dalton ATPase monomers and liposomes in the same preparations by radioactivity determination and counting of negatively stained images in the electron microscope indicated ATPase monomer to liposome ratios of 0.97 and 1.06. Because every liposome in the preparations must have had at least one ATPase monomer, these ratios indicate that very few of the liposomes had more than one, and simple calculations show that the great majority of active ATPase molecules in the preparations must have been present as proton-translocating monomers. The results thus clearly demonstrate that 105,000-dalton monomers of the Neurospora plasma membrane H+-ATPase can catalyze efficient ATP hydrolysis-driven proton translocation.

The recruitability and cell-cycle state of intestinal stem cells

Evidence is presented which suggests that the crypts of the small intestine contain at least two discrete but interdependent classes of stem cells, some with discrete cell kinetic properties and some with discrete radiation responses or radiosensitivities. Very low doses of X rays or gamma rays, or neutrons, kill a few cells in the stem cell regions of the crypt in a sensitive dose-dependent manner. Similar doses generate several different cell kinetic responses within either the clonogenic fraction or the cells at the stem cell position within the crypt. The cell kinetic responses range from apparent recruitment of G0 clonogenic cells into cycle, to a marked shortening of the average cell cycle of the cells at the stem cell position. It is suggested that the cell kinetic changes may be the consequence of the cell destruction.

Cell death (apoptosis) in the mouse small intestine after low doses: effects of dose-rate, 14.7 MeV neutrons, and 600 MeV (maximum energy) neutrons

The production of dead (apoptotic) cells by low doses of gamma-rays was independent of dose-rate between 0.27 and 450 cGy per min. The r.b.e. for doses of 14.7 MeV neutrons between 1 and 15 cGy was about 4, and for neutrons generated by bombarding a beryllium target with 600 MeV protons the r.b.e. was about 2.7. The dose-incidence curves for all three radiation types reached a plateau at about 3-4 dead cells per crypt section, and this occurred at about 20-40 cGy of gamma-rays. These curves are compatible with exponential survival of the cell population at risk (D0 of 24 cGy for gamma-rays, 6 cGy for 14.7 MeV neutrons and 9 cGy for 600 MeV neutrons). Since the dose-response is exponential there is no indication of much higher r.b.e. values at very low doses, a point of concern in radiation protection. The spatial distribution of dead cells in the crypt was similar after doses of gamma-rays or neutrons, indicating that the same population of target cells was affected in both cases.

Potential methodological errors in the application of equilibrium dialysis to the determination of "free" and "bound" plasma tryptophan

The application of equilibrium dialysis to the determination of the "free", i.e. non-albumin bound fraction of human plasma or serum tryptophan has been re-examined. A potentially serious error in the application of this method is outlined and the necessary correction and some precautionary measures are discussed.