Prevalence of new variants of Chlamydia trachomatis escaping detection by the Aptima Combo 2 assay, England, June to August 2019

We identified two new Chlamydia trachomatis (CT) variants escaping Aptima Combo 2 (AC2) assay detection, in clinical specimens of two patients. One had a C1514T mutation the other a G1523A mutation, both within the AC2 23S rRNA target region. The prevalence of such variants among persons tested for CT in England was estimated to be fewer than 0.003%.

National outbreak of Pseudomonas aeruginosa associated with an aftercare solution following piercings, July to September 2016, England

We report a national Pseudomonas aeruginosa outbreak from a common source following piercings between July and September 2016 in England. The multi-agency outbreak investigation included active case finding, microbiological testing of environmental samples and case specimens including Variable Number Tandem Repeat (VNTR) typing and a retrospective cohort study. Overall, 162 outbreak cases (29 confirmed, 14 probable and 119 possible) and 14 non-outbreak cases were identified; all confirmed cases had ear piercings (93% cartilage). Outbreak cases were predominantly female (95%) and had a median age of 18 years (interquartile range: 13-56 years). Nineteen outbreak cases required surgery under general anaesthetic The same outbreak VNTR type (11,3,5,3,3,3,6,4,7) was isolated from bottles of an aftercare solution from a single manufacturer and in specimens from confirmed cases who attended eight different piercing studios supplied with this product. In the cohort study, use of aftercare solution was associated with becoming a case (aOR: 4.60, 95% confidence interval: 1.65-12.90). Environmental, microbiological and epidemiological investigations confirmed that contamination during production of aftercare solution was the source of this national outbreak; highlighting challenges in the regulation of a cosmetic products used in the piercing industry and that guidance on piercing aftercare may need to be reviewed.

Acceptability and potential impact of delivering sexual health promotion information through social media and dating apps to MSM in England: a qualitative study

Background

Increasing rates of sexually transmitted infections (STIs) in men-who-have-sex-with-men (MSM) in England is a pressing public health concern. Interventions targeting MSM, including information provision that effectively promotes sexual health, are needed. To support such intervention development, it is necessary to understand acceptable ways of delivering sexual health information. We explored the acceptability and potential uses and impacts of delivering sexual health information to MSM through social media and geosocial networking apps or dating apps.

Methods

Semi-structured interviews were conducted in person or by telephone with 25 MSM resident in England recruited via dating apps and social media advertisements. Interviews explored sexual health information sources, perceptions and uses. Attitudes towards sexual health promotion through social media and dating apps were then discussed. The data were analysed using thematic analysis.

Results

Sexual health information delivery through social media and dating apps was considered acceptable. Receiving information when browsing social media was viewed positively by most, as people have time to absorb information. In contrast, concerns were expressed that sharing or commenting on social media sexual health information may lead to judgements and discrimination. While social media reaches a high proportion of the population, dating apps can easily target MSM. However, tensions exist between the ability to provide information at an opportune time through dating apps, when users are connecting with new sexual partners, with the potential to adversely affect the app user’s experience. Hypothetical and actual uses and impacts of sexual health information ranged from no impact to reading information, sharing with peers, and increased awareness, to influencing healthcare-seeking, decision-making and risk-taking behaviours. Ensuring that information is engaging, positive in tone, not too clinical, focused on building social norms and delivered by trusted organisations were viewed as important for supporting its use.

Conclusions

Overall, these findings support the development of new interventions that use dating apps and social media for sexual health promotion.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7558-7) contains supplementary material, which is available to authorized users.

Genomic approaches used to investigate an atypical outbreak of Salmonella Adjame

In 2017, an outbreak of gastroenteritis in England attributed to Salmonella Adjame was detected and investigated. With the introduction of whole genome sequencing (WGS) for microbial typing, methods for comparing international outbreak data require evaluation. A case was defined as a person resident in England with a clinical sample from 1 June 2017 to 27 July 2017 from whom S. Adjame was isolated. Cases were interviewed and exposures analysed. Backward tracing of food provenance was undertaken. WGS was performed on isolates from cases and historical isolates and compared using Public Health England’s SnapperDB high-quality SNP pipeline and Enterobase’s Salmonella core genome multi-locus sequence typing (cgMLST) scheme. In total, 14 cases were identified. The majority were vegetarian, probably of South Asian descent, with a median age of 66.5 years with no recent international travel reported. Cases consumed a range of fresh food products including herbs and spices bought from South Asian grocers. Backward tracing did not identify a common source. WGS typing showed sub-clustering and considerable genetic variation across human samples. cgMLST allele-based analysis was comparable to SNP-derived phylogenetic analysis and clusters were defined using each method. Imported herbs or spices were suspected vehicles. The cases were linked in time and place but WGS showed marked heterogeneity, atypical of a point source Salmonella outbreak. The application of incorporating SNP or allelic differences into the case definition may not always be appropriate. With further validation, cgMLST could be used for international outbreak alerts when WGS analysis is being undertaken to facilitate comparison.

Enhanced surveillance of syphilis cases among men who have sex with men in London, October 2016-January 2017

Syphilis rates have been increasing in men who have sex with men (MSM) in London. To describe risk behaviour and refine public health interventions, we conducted prospective enhanced surveillance of new syphilis cases in MSM attending selected London sexual health clinics (SHCs) between October 2016 and January 2017. Sexual health advisors (SHAs) completed 107 questionnaires. Eighteen per cent of respondents reported always using condoms, with lower use in HIV-positive (8%, 4/53) than HIV-negative men (33%, 14/52). Almost half of respondents reported condomless sero-discordant sex (46%, 33/72). The most frequent means of meeting new partners reported were venues (80%, 76/95), particularly bars or clubs (34%, 32/95), and apps or websites (79%, 75/95). Nearly a third of respondents reported engaging in group sex (32%, 30/95). Almost half reported drug use during sex (47%, 46/98), with HIV-positive men more likely to report use of the three main 'chemsex' drugs. The majority of respondents preferred health promotion information from SHAs (63%, 58/92) compared to other sources such as Google/Wikipedia and apps. Prevention activity should continue to focus on condomless sex, serosorting, multiple and overlapping partners, and chemsex. SHCs, particularly those serving HIV-positive men, are important sources for sexual health promotion advice.

Lack of Secondary Transmission of Ebola Virus from Healthcare Worker to 238 Contacts, United Kingdom, December 2014

In December 2014, Ebola virus disease (EVD) was diagnosed in a healthcare worker in the United Kingdom after the worker returned from an Ebola treatment center in Sierra Leone. The worker flew on 2 flights during the early stages of disease. Follow-up of 238 contacts showed no evidence of secondary transmission of Ebola virus.

National outbreak of Shiga toxin-producing Escherichia coli O157:H7 linked to mixed salad leaves, United Kingdom, 2016

We investigated a large outbreak of Escherichia coli O157 in the United Kingdom (UK) with 165 cases between 31 May and 29 July 2016. No linked cases were reported in other countries. Cases were predominately female (n = 128) and adult (n = 150), 66 attended hospital and nine had features of haemorrhagic uraemic syndrome. A series of epidemiological studies (case-control, case-case, ingredients-based and venue-based studies) and supply chain investigations implicated mixed salad leaves from Supplier A as the likely outbreak vehicle. Whole genome sequencing (WGS) indicated a link with strains from the Mediterranean and informed the outbreak control team to request that Supplier A cease distributing salad leaves imported from Italy. Microbiological tests of samples of salad leaves from Supplier A were negative. We were unable to confirm the source of contamination or the contaminated constituent leaf although our evidence pointed to red batavia received from Italy as the most likely vehicle. Variations in Shiga toxin-producing E.coli surveillance and diagnosis may have prevented detection of cases outside the UK and highlights a need for greater standardisation. WGS was useful in targeting investigations, but greater coverage across Europe is needed to maximise its potential.

ESBL-Producing and Macrolide-Resistant Shigella sonnei Infections among Men Who Have Sex with Men, England, 2015

In England in 2015, Shigella sonnei isolates from men who have sex with men produced extended-spectrum β-lactamases and exhibited macrolide resistance. Whole-genome sequencing showed a close relationship among the isolates, which harbored a plasmid that was previously identified in a shigellosis outbreak among this population but has acquired a mobile element.

Taste and Safety: Is the Exceptional Cuisine Offered by High End Restaurants Paralleled by High Standards of Food Safety?

Introduction: Restaurant guides such as the Good Food Guide Top 50 create a hierarchy focussing on taste and sophistication. Safety is not explicitly included. We used restaurant associated outbreaks to assess evidence for safety.

Methods: All foodborne disease outbreaks in England reported to the national database from 2000 to 2014 were used to compare the Top 50 restaurants (2015) to other registered food businesses using the Public Health England (PHE) outbreak database. Health Protection Teams were also contacted to identify any outbreaks not reported to the national database. Among Good Food Guide Top 50 restaurants, regression analysis estimated the association between outbreak occurrence and position on the list.

Results: Four outbreaks were reported to the PHE national outbreak database among the Top 50 giving a rate 39 times higher (95% CI 14.5–103.2) than other registered food businesses. Eight outbreaks among the 44 English restaurants in the Top 50 were identified by direct contact with local Health Protection Teams. For every ten places higher ranked, Top 50 restaurants were 66% more likely to have an outbreak (Odds Ratio 1.66, 95% CI 0.89–3.13).

Discussion: Top 50 restaurants were substantially more likely to have had reported outbreaks from 2000-2014 than other food premises, and there was a trend for higher rating position to be associated with higher probability of reported outbreaks. Our findings, that eating at some of these restaurants may pose an increased risk to health compared to other dining out, raises the question of whether food guides should consider aspects of food safety alongside the clearly important complementary focus on taste and other aspects of the dining experience.

A multi-country Salmonella Enteritidis phage type 14b outbreak associated with eggs from a German producer: ‘near real-time’ application of whole genome sequencing and food chain investigations, United Kingdom, May to September 2014

Binary file ES_Abstracts_Final_ECDC.txt matches

Olympics and Paralympics 2012 mass gathering in London: time-series analysis shows no increase in attendances at sexual health clinics

OBJECTIVE

To determine whether the 2012 Olympic and Paralympic Games were associated with a change in the number of patients attending or diagnosed with a new sexually transmitted infection (STI) at sexual health clinics in London and Weymouth.

METHODS

We undertook an interrupted time-series analysis of surveillance data from the Genitourinary Medicine Clinic Activity Dataset (GUMCAD) collected at 33 genitourinary medicine (GUM) clinics in London and Weymouth (where Games events were concentrated) between 2009 and 2012. Mixed-effects linear regression models of weekly attendance and diagnoses, incorporating temporal trends, bank holidays, categorical month and clinic closures, were used to test for the effect of the 'Olympic-Paralympic' period. We subdivided the 9-week 'Olympic-Paralympic' period (16 July 2012 to 17 September 2012) into five periods, including three Olympic weeks, two Paralympic weeks, pre-, post- and inter-Games weeks. We also compared characteristics of patients attending during the Olympic-Paralympic period and those attending during the same period in 2011.

RESULTS

During the 3 weeks of the Olympics, there was a significant reduction in the number of new episode attendances (2020 fewer, 5.6% reduction (95% CI -8.2 to -2.9)) and the number of patients diagnosed with an STI (267 fewer, 4.8% reduction (95% CI -8.6 to -0.9)) compared to expected. There were no important differences in the profile of patients attending during the 2012 Olympic-Paralympic period and those attending during the same period in 2011.

CONCLUSIONS

We conclude that a 'business-as-usual' approach to managing local sexual health clinics during the 2012 Olympic and Paralympics would have been appropriate.

Evaluation of the Health Protection Event-Based Surveillance for the London 2012 Olympic and Paralympic Games

The Health Protection Agency (HPA) (currently Public Health England) implemented the Health Protection Event-Based Surveillance (EBS) to provide additional national epidemic intelligence for the 2012 London Olympic and Paralympic Games (the Games). We describe EBS and evaluate the system attributes. EBS aimed at identifying, assessing and reporting to the HPA Olympic Coordination Centre (OCC) possible national infectious disease threats that may significantly impact the Games. EBS reported events in England from 2 July to 12 September 2012. EBS sourced events from reports from local health protection units and from screening an electronic application 'HPZone Dashboard' (DB). During this period, 147 new events were reported to EBS, mostly food-borne and vaccine-preventable diseases: 79 from regional units, 144 from DB (76 from both). EBS reported 61 events to the OCC: 21 of these were reported onwards. EBS sensitivity was 95.2%; positive predictive value was 32.8%; reports were timely (median one day; 10th percentile: 0 days - same day; 90th percentile: 3.6 days); completeness was 99.7%; stability was 100%; EBS simplicity was assessed as good; the daily time per regional or national unit dedicated to EBS was approximately 4 hours (weekdays) and 3 hours (weekends). OCC directors judged EBS as efficient, fast and responsive. EBS provided reliable, reassuring, timely, simple and stable national epidemic intelligence for the Games.

London 2012 Olympic and Paralympic Games: public health surveillance and epidemiology

Mass gatherings are regarded as potential risks for transmission of infectious diseases, and might compromise the health system of countries in which they are hosted. The evidence for increased transmission of infectious diseases at international sporting mass gatherings that attract many visitors from all over the world is not clear, and the evidence base for public health surveillance, epidemiology, and response at events such as the Olympics is small. However, infectious diseases are a recognised risk, and public health planning is, and should remain, a crucial part of the overall planning of sporting events. In this Series paper, we set out the planning and the surveillance systems that were used to monitor public health risks during the London 2012 Olympic and Paralympic Games in the summer of 2012, and draw attention to the public health issues-infectious diseases and chemical, radiation, and environmental hazards-that arose. Although the absolute risk of health-protection problems, including infectious diseases, at sporting mass gatherings is small, the need for reassurance of the absence of problems is higher than has previously been considered; this could challenge conventional public health surveillance systems. Recognition of the limitations of health-surveillance systems needs to be part of the planning for future sporting events.

Assessment of the impact of the London Olympics 2012 on selected non-genitourinary medicine clinic sexual health services

With minimal information on sexual health provision during mass-gathering events, our aim was to describe the use of sexual health, contraceptive, sex worker and sexual assault services during the London 2012 Olympics. We analysed data from five sources. One contraceptive service provider reported a 10% increase in attendance during the main Games, while emergency contraception prescriptions rose during the main Olympics, compared to the week before, but were similar or lower than at the beginning and end of the summer period. A health telephone advice line reported a 16% fall in sexual health-related calls during the main Olympics, but a 33% increase subsequently. London sexual assault referral centres reported that 1.8% of sexual assaults were Olympics-linked. A service for sex workers reported that 16% started working in the sex industry and 7% moved to London to work during the Olympics. Fifty-eight per cent and 45% of sex workers reported fewer clients and an increase in police crack-downs, respectively. Our results show a change in activity across these services during the 2012 summer, which may be associated with the Olympics. Our data are a guide to other services when anticipating changes in service activity and planning staffing for mass-gathering events.

Expanded HIV testing in high-prevalence areas in England: results of a 2012 audit of sexual health commissioners

OBJECTIVES

The aim of the study was to examine whether UK HIV testing guidelines which recommend the expansion of HIV testing in high HIV prevalence areas have been implemented in England.

METHODS

An online survey tool was used to conduct an audit of sexual health commissioners in 40 high HIV prevalence areas (diagnosed prevalence > 2 per 1000) between May and June 2012. Responders were asked to provide details of expanded HIV testing programmes that they had commissioned in nontraditional settings and perceived barriers and facilitators involved in introducing expanded testing.

RESULTS

The response rate was 88% (35 of 40). Against the key audit standards, 31% (11 of 35) of areas had commissioned routine testing of new registrants in general practice, and 14% (five of 35) routine testing of general medical admissions. The majority of responders (80%; 28 of 35) had commissioned some form of expanded testing, often targeted at risk groups. The most common setting for commissioning of testing was the community (51%; 18 of 35), followed by general practice (49%; 17 of 35) and hospital departments (36%; 13 of 35). A minority (11%; four of 35) of responders had commissioned testing in all three settings. Where testing in general practice took place this was typically in a minority of practices (median 10-20%). Most (77%; 27 of 35) expected the rate of HIV testing to increase over the next year, but lack of resources was cited as a barrier to testing by 94% (33 of 35) of responders.

CONCLUSIONS

Not all high HIV prevalence areas in England have fully implemented testing guidelines. Scale-up of existing programmes and continued expansion of testing into new settings will be necessary to achieve this.

Ongoing outbreak of Shigella flexneri serotype 3a in men who have sex with men in England and Wales, data from 2009-2011

Diagnoses of Shigella flexneri in the United Kingdom (UK) are usually travel-related. However, since 2009, there has been an overall increase in UK-acquired cases. The Health Protection Agency has been investigating a national outbreak of S. flexneri detected in 2011 and which is still ongoing. Cases occurred mostly in men who have sex with men and were of serotype 3a. The investigation aimed at obtaining epidemiological data to inform targeted outbreak management and control.

Ethnic differences in patient perceptions of heart failure and treatment: the West Birmingham heart failure project

OBJECTIVE

To investigate further the hypothesis that ethnic groups would have different levels of knowledge and perceptions of congestive heart failure (CHF) and treatments for this condition, a cross sectional survey was conducted of patients who were attending the heart failure clinics in two teaching hospitals of Birmingham, UK, that serve a multiethnic population.

METHODS

103 patients with CHF (66 men, 37 women) were surveyed by standard questionnaire: 42 were white, 34 Indo-Asian, 22 Afro-Caribbean, and 5 Oriental.

RESULTS

When asked about their beliefs about control of one's health, 22 (64.7%) of Indo-Asians felt that God/fate controlled their health. The majority of white patients tended to believe that the greatest factor influencing their health was the doctor (15 (35.7%)). Of the total study cohort, only 68 (66%) of patients were aware of their primary diagnosis of heart failure; the majority of Indo-Asians (21 (61.8%)) were not aware of their diagnosis. Half of Indo-Asians (17 (50%)) felt that heart failure was not severe, in contrast to 40.9% (n = 9) of Afro-Caribbeans and only 19.1% (n = 8) of white patients. Of the study cohort, 38 (36.9%) were taking their drugs because their doctor told them to, a response most common among the Indo-Asians. The majority of Indo-Asians (22 (64.7%)) and Afro-Caribbeans (14 (63.6%)) stated that they did not have, or did not know whether they had enough, information about their drug. The corresponding figure for white patients was 21.4% (n = 9). When asked whether they took their medication regularly as prescribed, 7 (31.8%) of Afro-Caribbeans reported that they did not take their drugs regularly.

CONCLUSIONS

Our study has highlighted deficiencies in the knowledge of CHF among patients from ethnic minority groups, as well as deficiencies in the information being given to these patients. There is a clear need to invest more in patient education for CHF, with special emphasis on certain high risk subgroups.

Burden and cost of imported infections admitted to infectious diseases units in England and Wales in 1998 and 1999

BACKGROUND

International travel from the UK has been rising, and the number of imported infections has increased. This study aimed to describe the number, nature, origin, clinical burden and cost of imported infections treated in infectious disease units (IDU) in England and Wales.

METHOD

Information about all admissions in 1998 and 1999 with illnesses considered to have been acquired during their most recent travel abroad was collected retrospectively by IDUs using a pre-piloted questionnaire.

RESULTS AND ANALYSIS

Four of the 23 IDUs in England and Wales were able to complete the questionnaires. They reported a total of 421 travel related admissions during the 2-year period. Three hundred and ninety-two of these cases were attributed to infectious causes, and of these a discharge diagnosis was made for 340 cases. The total number of bed days used to treat cases of imported infection was 2918. The most common diagnosis was malaria. The odds ratio that cases of imported infection were malaria was highest following visits to Africa. The average cost per bed day on the IDUs was around pound sterling 100, and on this basis, the total cost of treating imported infections on the four IDUs in 2 years was around pound sterling 289,000. The relative risk of acquiring an imported infection requiring treatment on an IDU was greatest for travellers to Africa.

CONCLUSIONS

From this study, the estimate of the total annual cost of IDU treatment for imported infections in England and Wales is in excess of pound sterling 800,000. Many cases may be preventable with prophylactic medication and vaccination and travel advice on risk reduction. Further information about imported infections would be useful to inform travel medicine services, other clinicians and travellers about the health risks associated with travel to specific areas, and help to target and assess the cost effectiveness of preventative measures.

Enhancing surveillance of cryptosporidiosis: test all faecal specimens from children

The heightened risk of waterborne cryptosporidiosis, associated with heavy rainfall in autumn 2000, prompted us to survey laboratory practice in the South East Region of England in testing faecal specimens for Cryptosporidium spp. oocysts and reporting to the Public Health Laboratory Service Communicable Disease Surveillance Centre (PHLS CDSC). Varied practices were found. Ideally, all faecal specimens should be tested, but where laboratories are unable to do so, screening all faecal specimens from children age 15 years or younger would improve surveillance and could probably be accomplished with minimal additional resources.

Early predictors of mortality in pneumococcal bacteraemia

OBJECTIVES

Pneumococcal bacteraemia carries a mortality of about 20%. Approximately 50% of deaths from pneumococcal bacteraemia occur within the first 48 h of admission. In order to influence outcome, critically ill patients should be identified at the time of presentation. This study enables the clinician to rapidly make an evidence-based assessment of a patient's prognosis, allowing the identification of patients who should be placed in a high-risk category at an early stage, when appropriate management is most likely to be effective.

METHODS

Data were collected from the medical record of history, physical examination, radiological examination and laboratory investigations done on initial presentation using a standardized proforma. The data were first examined by Pearson's Chi-squared test, with Yates' correction if needed. Variables found to be significantly associated with case fatality ( P < 0.05) by these methods were examined by stepwise logistic regression analysis in order to identify those factors which were independent predictors of case fatality.

RESULTS

The overall case fatality was 21%. Older age, apyrexia, tachypnoea, bilateral consolidation, hypoalbuminaemia, elevated aminotransferases, renal impairment, acidosis and leucopaenia were significantly associated with higher case fatality. Older age, acidosis and elevated serum alanine aminotransferase (ALT) were independent predictors of case fatality. Fifty-five percent of isolates belonged to serotypes 4, 6B, 9V, 14, 19F and 23F, to which good antibody levels have been documented in both young and elderly patients post-vaccination. Serotype 14 was most common, and was significantly associated with higher case fatality. Colder weather was associated with a higher incidence of both infection and case fatality. The case fatality amongst patients receiving ITU management was 44%. Less than 50% of patients who died received ITU management.

CONCLUSIONS

Despite the increased availability of new antibiotics and vaccines, the mortality of patients with pneumococcal bacteraemia remains unchanged. The parameters above allow early identification of patients with a higher case fatality; these patients may benefit from being placed in a "high-risk" category early on in their management. Vaccination of the elderly may reduce the incidence and/or mortality from pneumococcal bacteraemia. Further studies are required to understand the reasons for referral for intensive therapy in acute pneumococcal bacteraemia and whether ITU management affects outcome.

The role of nitric oxide as an endogenous regulator of platelet and neutrophil activation within the pulmonary circulation of the rabbit

1. Intravenous (i.v.) administration of adenosine diphosphate (ADP), platelet activating factor (PAF) and thrombin induced a dose-related accumulation of 111indium-labelled platelets within the thoracic region of anaesthetized rabbits. 2. I.v. administration of the inhibitor of NO biosynthesis, L-NG-nitro arginine methyl ester (L-NAME; 10 mg kg-1) significantly potentiated the peak platelet accumulation induced by ADP, PAF and thrombin. Additionally L-NAME prolonged the disaggregation of platelets in comparison to D-NAME (10 mg kg-1). Such changes were reversible by the administration of L-arginine (900 mg kg-1). 3. I.v. administration of PAF induced a small accumulation of 111indium-labelled neutrophils within the pulmonary circulation which could be greatly potentiated by pretreatment of the animals with L-NAME. In contrast, thrombin administration did not cause significant accumulation of 11indium-labelled erythrocytes in the pulmonary circulation of anaesthetized rabbits. 4. Intracarotid (i.c.) administration of thrombin induced a marked accumulation of radiolabelled platelets within the cranial vasculature which was not potentiated by the prior administration of L-NAME (at either 10 mg kg-1 or 100 mg kg-1). 5. These results suggest that endogenous NO may regulate platelet and polymorphonuclear leukocyte activation within the pulmonary but not the cerebral circulation of rabbits.

Altered platelet function associated with the bronchial hyperresponsiveness accompanying nocturnal asthma

BACKGROUND

Nocturnal awakening is a common feature of bronchial asthma, and yet the mechanisms underlying this phenomenon are poorly understood. We investigated whether nocturnal awakening is associated with changes in platelet function with the use of a variety of markers of platelet activation.

METHODS

Ten patients with a history of nocturnal asthma and 10 age- and sex-matched healthy control subjects were studied at 10:00 PM, 4:00 AM, and 10:00 AM on 2 consecutive days. The following parameters were tested: forced expiratory volume in 1 second (FEV1), log dose of methacholine inducing a 20% fall in FEV1, platelet count and volume, platelet aggregation induced by collagen or activating factor, and plasma and intraplatelet levels of beta-thromboglobulin and platelet factor 4.

RESULTS

We have demonstrated that altered platelet function and platelet activation occurs at 4:00 AM in patients with nocturnal asthma and is associated with the maximum increases in bronchial reactivity. Such changes were not observed in 10 control subjects. Platelet dysfunction has been detected as a reduced aggregatory response of platelets to collagen and platelet activating factor such that up to 5 times more platelet activating factor and 1.5 times more collagen were required to elicit a threshold aggregatory response in asthmatic subjects when compared with control subjects; this difference was evident at all time points tested. Furthermore, at 4:00 AM there were significantly lower levels of intraplatelet beta-thromboglobulin corresponding to the maximum reduction in peak expiratory flow and to the maximal increase in bronchial responses to inhaled methacholine.

CONCLUSIONS

These results suggest that platelet activation accompanies nocturnal asthma and further suggest that platelets may play a role in this common clinical condition.

The pharmacological modulation of thrombin-induced cerebral thromboembolism in the rabbit

1. Intracarotid (i.c.) administration of thrombin induced a marked accumulation of 111indium-labelled platelets and 125I-labelled fibrinogen within the cranial vasculature of anaesthetized rabbits. 2. Thrombin (100 iu kg-1, i.c.) - induced platelet accumulation was completely abolished by pretreatment with desulphatohirudin (CGP 39393; 1 mg kg-1 i.c., 1 min prior to thrombin). Administration of CGP 39393 1 or 20 min after thrombin produced a significant reduction in platelet accumulation. 3. Intravenous (i.v.) administration of the platelet activating factor (PAF) receptor antagonist BN 52021 (10 mg kg-1) 5 min prior to thrombin (100 iu kg-1, i.c.) had no effect on platelet accumulation. 4. An inhibitor of NO biosynthesis, L-NG-nitro arginine methyl ester (L-NAME; 100 mg kg-1, i.c.), had no significant effect on the cranial platelet accumulation response to thrombin (10 iu kg-1, i.c.) when administered 5 min prior to thrombin. 5. Defibrotide (32 or 64 mg kg-1 bolus i.c. followed by 32 or 64 mg kg-1 h-1, i.c., infusion for 45 min) treatment begun 20 min after thrombin (100 iu kg-1, i.c.) did not significantly modify the cranial platelet accumulation response. 6. Cranial platelet accumulation induced by thrombin (100 iu kg-1, i.c.) was significantly reversed by the fibrinolytic drugs urokinase (20 iu kg-1, i.c., infusion for 45 min), anisoylated plasminogen streptokinase activator complex (APSAC) (200 micrograms kg-1, i.v. bolus) or recombinant tissue plasminogen activator (rt-PA; 100 micrograms kg-1, i.c. bolus followed by 20 micrograms kg-1 min-1, i.c., infusion for 45 min) administered 20 min after thrombin.8. These results suggest that neither endogenous PAF nor NO modulate thrombin-induced intracranial platelet accumulation in the rabbit. However, fibrin deposition appears to play an important role as shown by the ability of fibrinolytic agents to reverse platelet and fibrinogen accumulation induced by i.c. thrombin.

The involvement of platelet activating factor in endotoxin-induced pulmonary platelet recruitment in the guinea-pig

1 Exposure of conscious guinea-pigs to an aerosol of endotoxin (25-100 micrograms ml-1) resulted in a dose-related, progressive accumulation of platelets in the thoracic region. Accumulation of 111indium oxine labelled erythrocytes was not observed following exposure to an aerosol of endotoxin (50 micrograms ml-1). 2 Pretreatment of guinea-pigs with the selective platelet activating factor (Paf)-antagonists. CV-3988 or brotizolam resulted in a dose-related inhibition of endotoxin-induced pulmonary platelet recruitment. Pretreatment of guinea-pigs with the selective Paf-antagonist BN 52021 resulted in significant inhibition of endotoxin-induced pulmonary platelet recruitment, although the effects of BN 52021 were not dose-related. 3 Pretreatment of guinea-pigs with indomethacin at doses known to inhibit cyclo-oxygenase did not inhibit endotoxin-induced pulmonary platelet recruitment, whereas higher doses of indomethacin produced a reduction in platelet recruitment in the lung. 4 Pretreatment of guinea-pigs with the anticoagulant heparin and the prostacyclin analogue ZK 36374 inhibited endotoxin-induced platelet recruitment. 5 These observations suggest that endotoxin-induced pulmonary platelet recruitment in the guinea-pig is secondary to the release of platelet activating factor, but not to cyclo-oxygenase products of arachidonic acid and may also involve activation of the coagulation cascade.