International review of blood donation nucleic acid amplification testing

BACKGROUND AND OBJECTIVES

Nucleic acid amplification testing (NAT), in blood services context, is used for the detection of viral and parasite nucleic acids to reduce transfusion-transmitted infections. This project reviewed NAT for screening blood donations globally.

MATERIALS AND METHODS

A survey on NAT usage, developed by the International Society of Blood Transfusion Working Party on Transfusion-transmitted Infectious Diseases (ISBT WP-TTID), was distributed through ISBT WP-TTID members. Data were analysed using descriptive statistics.

RESULTS

Forty-three responses were received from 32 countries. Increased adoption of blood donation viral screening by NAT was observed over the past decade. NAT-positive donations were detected for all viruses tested in 2019 (proportion of donations positive by NAT were 0.0099% for human immunodeficiency virus [HIV], 0.0063% for hepatitis C virus [HCV], 0.0247% for hepatitis B virus [HBV], 0.0323% for hepatitis E virus [HEV], 0.0014% for West Nile virus [WNV] and 0.00005% for Zika virus [ZIKV]). Globally, over 3100 NAT-positive donations were identified as NAT yield or solely by NAT in 2019 and over 22,000 since the introduction of NAT, with HBV accounting for over half. NAT-positivity rate was higher in first-time donors for all viruses tested except WNV. During 2019, a small number of participants performed NAT for parasites (Trypanosoma cruzi, Babesia spp., Plasmodium spp.).

CONCLUSION

This survey captures current use of blood donation NAT globally. There has been increased NAT usage over the last decade. It is clear that NAT contributes to improving blood transfusion safety globally; however, there is a need to overcome economic barriers for regions/countries not performing NAT.

An international review of the characteristics of viral nucleic acid-amplification testing (NAT) reveals a trend towards the use of smaller pool sizes and individual donation NAT

BACKGROUND AND OBJECTIVES

Nucleic acid-amplification testing (NAT) is used for screening blood donations/donors for blood-borne viruses. We reviewed global viral NAT characteristics and NAT-yield confirmatory testing used by blood operators.

MATERIALS AND METHODS

NAT characteristics and NAT-yield confirmatory testing used during 2019 was surveyed internationally by the International Society of Blood Transfusion Working Party Transfusion-Transmitted Infectious Diseases. Reported characteristics are presented herein.

RESULTS

NAT was mainly performed under government mandate. Human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV) NAT was performed on all donors and donation types, while selective testing was reported for West Nile virus, hepatitis E virus (HEV), and Zika virus. Individual donation NAT was used for HIV, HCV and HBV by ~50% of responders, while HEV was screened in mini-pools by 83% of responders performing HEV NAT. Confirmatory testing for NAT-yield samples was generally performed by NAT on a sample from the same donation or by NAT and serology on samples from the same donation and a follow-up sample.

CONCLUSION

In the last decade, there has been a trend towards use of smaller pool sizes or individual donation NAT. We captured characteristics of NAT internationally in 2019 and provide insights into confirmatory testing approaches used for NAT-yields, potentially benefitting blood operators seeking to implement NAT.

Evolutionary remodelling of N-terminal domain loops fine-tunes SARS-CoV-2 spike

The emergence of SARS-CoV-2 variants has exacerbated the COVID-19 global health crisis. Thus far, all variants carry mutations in the spike glycoprotein, which is a critical determinant of viral transmission being responsible for attachment, receptor engagement and membrane fusion, and an important target of immunity. Variants frequently bear truncations of flexible loops in the N-terminal domain (NTD) of spike; the functional importance of these modifications has remained poorly characterised. We demonstrate that NTD deletions are important for efficient entry by the Alpha and Omicron variants and that this correlates with spike stability. Phylogenetic analysis reveals extensive NTD loop length polymorphisms across the sarbecoviruses, setting an evolutionary precedent for loop remodelling. Guided by these analyses, we demonstrate that variations in NTD loop length, alone, are sufficient to modulate virus entry. We propose that variations in NTD loop length act to fine-tune spike; this may provide a mechanism for SARS-CoV-2 to navigate a complex selection landscape encompassing optimisation of essential functionality, immune-driven antigenic variation and ongoing adaptation to a new host.

Fatal COVID-19 outcomes are associated with an antibody response targeting epitopes shared with endemic coronaviruses

The role of immune responses to previously seen endemic coronavirus epitopes in severe acute respiratory coronavirus 2 (SARS-CoV-2) infection and disease progression has not yet been determined. Here, we show that a key characteristic of fatal outcomes with coronavirus disease 2019 (COVID-19) is that the immune response to the SARS-CoV-2 spike protein is enriched for antibodies directed against epitopes shared with endemic beta-coronaviruses and has a lower proportion of antibodies targeting the more protective variable regions of the spike. The magnitude of antibody responses to the SARS-CoV-2 full-length spike protein, its domains and subunits, and the SARS-CoV-2 nucleocapsid also correlated strongly with responses to the endemic beta-coronavirus spike proteins in individuals admitted to an intensive care unit (ICU) with fatal COVID-19 outcomes, but not in individuals with nonfatal outcomes. This correlation was found to be due to the antibody response directed at the S2 subunit of the SARS-CoV-2 spike protein, which has the highest degree of conservation between the beta-coronavirus spike proteins. Intriguingly, antibody responses to the less cross-reactive SARS-CoV-2 nucleocapsid were not significantly different in individuals who were admitted to an ICU with fatal and nonfatal outcomes, suggesting an antibody profile in individuals with fatal outcomes consistent with an "original antigenic sin" type response.

Longitudinal variation in SARS-CoV-2 antibody levels and emergence of viral variants: a serological analysis

BACKGROUND

Serological assays are being used to monitor antibody responses in individuals who had SARS-CoV-2 infection and those who received a COVID-19 vaccine. We aimed to determine whether such assays can predict neutralising antibody titres as antibody levels wane and viral variants emerge.

METHODS

We measured antibody levels in serum samples from a cohort of 112 participants with SARS-CoV-2 infection using ten high-throughput serological tests and functional neutralisation assays. Serum samples were taken at baseline and at up to four subsequent visits. We assessed the effects of time and spike protein sequence variation on the performance and predictive value of the various assays. We did correlation analyses for individual timepoints using non-parametric Spearman correlation, and differences between timepoints were determined by use of a two-tailed Wilcoxon matched-pairs signed rank test.

FINDINGS

Neutralising antibody titres decreased over the first few months post-infection but stabilised thereafter, at about 30% of the level observed shortly after infection. Serological assays commonly used to measure antibodies against SARS-CoV-2 displayed a range of sensitivities that declined to varying extents over time. Quantitative measurements generated by serological assays based on the spike protein were better at predicting neutralising antibody titres than those based on nucleocapsid, but performance was variable, and manufacturer positivity thresholds were not able to predict the presence or absence of detectable neutralising activity. Although we observed some deterioration in correlation between serological measurements and functional neutralisation activity, some assays maintained an ability to predict neutralising titres, even against variants of concern.

INTERPRETATION

The ability of high-throughput serological assays to predict neutralising antibody titres is likely to be crucial for evaluation of immunity at the population scale. These data can facilitate the selection of the most suitable assays as surrogates of functional neutralising activity and suggest that such measurements might be useful in clinical practice.

FUNDING

US National Institutes of Health and National Health Service Research Scotland BioResource.

Unobtrusive, Continuous LIDAR-Based Measurement of Gait Characteristics at Home

This paper describes a novel approach to the unobtrusive assessment of a subset of gait characteristics using a light detection and ranging (LIDAR) device. The developed device is poised to enable unobtrusive, nearly continuous monitoring and inference of patients' gait characteristics to assess physical and cognitive states. The device provides a rapidly sampled signal representing the distance of a participant's body from the LIDAR device. The densely sampled distance estimation is processed by custom algorithms that can potentially be used to estimate various gait characteristics such as step size, cadence, double support, and even step-size symmetry.Clinical Relevance- Since gait is a complex behavior that requires seamless cooperation of multiple systems, including sensation, perception, muscular synergies, and even cognition. Subtle changes in gait may, therefore, indicate issues with physical and mental functionality. In addition to the walking speed, the gait monitoring results can provide inferences about the physical and cognitive states of the unobtrusively monitored individuals using their own data as a baseline.

Comparison of SARS-CoV-2 serological assays for use in epidemiological surveillance in Scotland

Background

Sero-surveillance of SARS-CoV-2 is crucial to monitoring levels of population exposure and informing public health responses, but may be influenced by variability in performance between available assays.

Methods

Five commercial immunoassays and a neutralising activity assay were used to detect antibodies to SARS-CoV-2 in routine primary care and paediatric samples collected during the first wave of the pandemic in NHS Lothian, Scotland as part of ongoing surveillance efforts. For each assay, sensitivity and specificity was calculated relative to consensus results (majority of immunoassays positive = overall positive) and neutralising activity. Quantitative correlation was performed between serological and neutralising titres.

Results

Seroprevalence ranged from 3.4-7.3 % in primary care patients and 3-5.9 % in paediatric patients according to different immunoassays. Neutralising activity was detectable in 2.8 % and 1.3 % respectively. Relative assay performance changed depending on comparison to immunoassay consensus versus neutralising activity and qualititative versus quantitative agreement. Cross-reactivity with endemic seasonal coronaviruses was confirmed by neutralising assay in false positives for one immunoassay. Presence of false positives for another assay was found specifically in paediatric but not adult samples.

Conclusions

Five serological assays show variable accuracy when applied to the general population, impacting seroprevalence estimates. Assay performance may also vary in detection of protective neutralising antibody levels. These aspects should be considered in assay selection and interpretation in epidemiological studies.

Application of QMRA to prioritise water supplies for Cryptosporidium risk in New South Wales, Australia

A Quantitative Microbial Risk Assessment (QMRA) framework was applied to assess 312 drinking water supply systems across regional New South Wales (NSW). The framework was needed to support the implementation of a recommendation in the Australian Drinking Water Guidelines (ADWG) for appropriate treatment barriers to be operating in systems 'at risk' for Cryptosporidium. The objective was to prioritise systems so that those with the highest risk could be identified and addressed first. The framework was developed in a pilot study of 30 systems, selected to represent the range of water supplies across regional NSW. From these, source water categories were defined to represent local conditions with reference to the literature and Cryptosporidium risk factors. Values for Cryptosporidium oocyst concentration were assigned to the categories to allow quantification of the health risk from those water sources. The framework was then used to assess the risks in all 312 regional drinking water supply systems. Combining the disciplined approach of QMRA with simple catchment and treatment information and categorical risk outputs provided a useful and transparent method for prioritising systems for further investigation and potential risk management intervention. The risk rankings for drinking water supplies from this QMRA process have been used to set priorities for a large State Government funding program.

Longitudinal variation in SARS-CoV-2 antibody levels and emergence of viral variants: implications for the ability of serological assays to predict immunity

BACKGROUND

Serological assays are being deployed to monitor antibody responses in SARS-CoV-2 convalescents and vaccine recipients. There is a need to determine whether such assays can predict immunity, as antibody levels wane and viral variants emerge.

METHODS

We measured antibodies in a cohort of SARS-CoV-2 infected patients using several high-throughput serological tests and functional neutralization assays. The effects of time and spike protein sequence variation on the performance and predictive value of the various assays was assessed.

FINDINGS

Neutralizing antibody titers decreased over the first few months post-infection but stabilized thereafter, at about 30% of the level observed shortly after infection. Serological assays commonly used to measure antibodies against SARS-CoV-2 displayed a range of sensitivities that declined to varying extents over time. Quantitative measurements generated by serological assays based on the spike protein were better at predicting neutralizing antibody titers than assays based on nucleocapsid, but performance was variable and manufacturer positivity thresholds were not able to predict the presence or absence of detectable neutralizing activity. Even though there was some deterioration in correlation between serological measurements and functional neutralization activity, some assays maintained an ability to predict neutralizing titers, even against variants of concern.

INTERPRETATION

The ability of high throughput serological assays to predict neutralizing antibody titers is likely crucial for evaluation of immunity at the population scale. These data will facilitate the selection of the most suitable assays as surrogates of functional neutralizing activity and suggest that such measurements may have utility in clinical practice.

Patterns of Hepatitis G Viraemia and Liver Disease in Haemophiliacs Previously Exposed to Non-virus Inactivated Coagulation Factor Concentrates

Hepatitis G virus (HGV), a novel flavivirus, has been implicated as a cause of posttransfusion hepatitis. We have performed a longitudinal study in a cohort of haemophiliacs (n = 68) who previously received non-virus inactivated coagulation factor concentrates to assess both patterns of HGV viraemia and any associated liver disease. Hepatitis C virus (HCV) RNA was present in 58/68 and co-infection with human immunodeficiency virus (HIV) was present in 15/68.

HGV RNA was detected in 17/68 (25%) samples from the mid-1980s. There was no association between either HIV infection (p = 0.74) or co-infection with a particular HCV genotype (p = 0.62). However, there was a relationship between HGV viraemia and the severity of haemophilia (p = 0.0004) with HGV RNA detected in 5/19, 9/16 and 3/32 patients with mild, moderate and severe haemophilia respectively.

A longitudinal study was performed in 15/17 haemophiliacs with HGV viraemia using stored serum samples from the 1980s and 1990s. HGV viraemia persisted in 8/15 and cleared in 7/15 over a variable period of time. A Weibull model was constructed to estimate the duration of HGV viraemia in the study group. The 75th and 90th percentiles for the duration of HGV were estimated to be 8.7 years (95%, confidence interval 4.8-15.7) and 23.6 years (95% confidence interval 11.8-47.1) respectively. Laparoscopic liver inspection/biopsy was performed in 25/68. There was no association between severity of liver disease and HGV viraemia (p = 0.43). This study demonstrates considerable variation in patterns of HGV viraemia in haemophiliacs. We found little evidence to implicate HGV as a major cause of chronic liver disease in haemophiliacs.

16: POSTPARTUM DEPRESSION SCREENING IN A PEDIATRIC ED

Purpose of Study

Postpartum depression (PPD) occurs in up to 20% of mothers. The American Academy of Pediatrics recommends routine screening for PPD. The pediatric emergency department (PED) serves as a safety-net for vulnerable, high-risk populations, and may be a useful site for screening. This study investigates (1) prevalence of PPD positive screens, (2) factors associated with a positive PPD screen, (3) frequency of mothers who had not completed a PPD screen previously, and (3) acceptability and impact of PPD screening.

Methods Used

We performed a prospective, cross-sectional survey of a convenience sample of mothers of infants </=6 months of age presenting with low-acuity complaints. Mothers completed a computerized survey that included a validated PPD screening tool (Edinburgh Postnatal Depression Scale). We calculated frequency of positive screens and performed bivariable logistic regression to identify factors associated with a positive PPD screen. PPD positive-screened mothers were contacted for phone follow-up at one-month.

Summary of Results

121 mothers were screened for PPD (mean age=28± SD 6 years; 86% English vs. Spanish language; 50% non-Hispanic Black race/ethnicity; 75% non-private insurance) during presentation to the ED with their infant (mean age=3±SD 2 months; 51% female). Twenty-seven mothers (22%) screened positive for PPD with eight mothers (7%) reporting suicidal thoughts. Forty-seven percent (57/121) of mothers had never previously been screened, including 59% (16/27) of PPD-positive screened and those endorsing suicidal thoughts (5/8, 63%). Infants of PPD-screened positive mothers had more ED visits than those whose mothers screened negative (median 2 vs. 1). Seventy-four percent (90/121) of participants viewed ED-based PPD screening favorably. At one-month follow-up 100% (n=12) reported ED-based PPD screening acceptable and the majority endorsed positive impact of screening, including increased access to support (8/12, 67%) and improved activities of daily living (10/12, 83%).

Conclusions

PPD is reported by approximately 1 in 5 mothers in an urban PED and the majority of PED-screen positive mothers had not been screened previously. PED-based screening was well-accepted and had a positive impact. Our study informs future efforts for interventions to support mothers of young infants who use the PED for care.

P7: POSTPARTUM DEPRESSION POSITIVE SCREEN PREDICTORS IN A PEDIATRIC ED

Purpose of Study

The World Health Organization (WHO) and Toronto Public Health (TPH) performed a systematic literature review to identify predictors for different risk categories for postpartum depression (PPD). This review did not include patients in the pediatric emergency department (PED) setting. This study determines if the predictors identified in the WHO/TPH review are associated with positive PPD screens in an urban PED.

Methods Used

We performed a prospective, cross-sectional survey of a convenience sample of mothers presenting with low-acuity triage level infants </=six months old to a PED. We calculated frequency of positive PPD screen predictors and performed multivariable logistic regression to identify association with a positive PPD screen.

Summary of Results

121 mothers were screened for PPD during presentation to the PED with their infant; 27 (22%) screened positive. Adjusting for maternal age, race/ethnicity, and insurance status, WHO/TPH “strong” predictors of a previous history of depression (aOR 6.7; 95% CI 1.6, 28.6), a previous history of anxiety (aOR 16.1; 95% CI 2.1, 125.5), depressed mood or anxiety during this pregnancy (aOR 25.6; 95% CI 6.7, 98.2), a recent stressful life event (aOR 5.4; 95% CI 1.9, 15.2), and lack of social support (report that they did not have someone they could count on to help with the baby; aOR 6.5; 95% CI 1.6, 26.9) were significantly associated with a positive PPD screen. “Moderate” predictors of infant fussiness, (all/most of the time; aOR 8.4; 95% CI 2.0, 35.3) and high levels of childcare stress (all/most of the time; aOR 4.6; 95% CI 1.7, 12.4) were significantly associated with a positive screen. “Small” predictors of quality of relationship with the partner (sometimes vs. all/most of the time having a good relationship with the partner; aOR 3.8; 95% CI 1.0, 6.3) was significantly associated; obstetric and pregnancy complications and socioeconomic status were not significantly associated. Our study was consistent with the WHO/TPH review which found no association of PPD with ethnicity, maternal age, education level, parity, or gender of the child.

Conclusions

Results in this urban PED are largely consistent with WHO/TPH predictors of PPD developed in other settings. Understanding PPD predictors can help physicians to improve screening and identification of PPD positive mothers.

The Joint Theatre Clinical Case Conference (JTCCC): clinical governance in action

OBJECTIVES

To quantify the type and nature of the lessons and issues arising from the Joint Theatre Clinical Case Conference

METHODS

An evaluation of all JTCCC minutes from inception on 30 Mar 07 to 05 Jun 08 (n = 61) was performed in Jul 08. Each separate issue (n = 207) was assigned a NATO 'J' category and further sub-divided into clinical and non-clinical issues. Detail of whether the issues were raised for information only, or required action to be taken was recorded, as was the outcome of this action.

RESULTS

A wide range of clinical and non-clinical issues (J1-J8), were identified. 23% (47) of the 207 issues were raised for information only. 77% (160) issues required action to be taken. 109 were dosed within 3 weeks. 23 took more than 3 weeks to close. Eight weeks after the study period 28 issues were still being actively resolved. 85% of JTCCC teleconferences had full participation from both theatres. Technical difficulties and/or the treatment of casualties prevented the participation of one or both theatres on 9 occasions.

CONCLUSIONS

JTCCC supports deployed clinicians and enables rapid resolution of issues affecting combat casualty care. It is limited by its focus on UK casualties only. Although intended as a Clinical Governance tool the evidence of this review is that JTCCC has wider effects in a number of clinical and non-clinical areas.

Word learning and the cerebral hemispheres: from serial to parallel processing of written words

Reading familiar words differs from reading unfamiliar non-words in two ways. First, word reading is faster and more accurate than reading of unfamiliar non-words. Second, effects of letter length are reduced for words, particularly when they are presented in the right visual field in familiar formats. Two experiments are reported in which right-handed participants read aloud non-words presented briefly in their left and right visual fields before and after training on those items. The non-words were interleaved with familiar words in the naming tests. Before training, naming was slow and error prone, with marked effects of length in both visual fields. After training, fewer errors were made, naming was faster, and the effect of length was much reduced in the right visual field compared with the left. We propose that word learning creates orthographic word forms in the mid-fusiform gyrus of the left cerebral hemisphere. Those word forms allow words to access their phonological and semantic representations on a lexical basis. But orthographic word forms also interact with more posterior letter recognition systems in the middle/inferior occipital gyri, inducing more parallel processing of right visual field words than is possible for any left visual field stimulus, or for unfamiliar non-words presented in the right visual field.

Food portion weights in primary and secondary school lunches in England

BACKGROUND

National Nutritional Standards for school lunches were reintroduced in 2001, and included guidance on portion sizes for primary schools. For the first time since 1997, nationally representative data on school food portion sizes in England have been collected using direct assessment rather than reported portion sizes.

METHODS

Food portions were weighed directly in foods served in nationally representative samples of primary and secondary school meals. Results were grouped by food or food group.

RESULTS

The number of portions weighed was 7975 in primary schools and 3354 in secondary schools. Individual portion weights were grouped by food or food group to yield mean, median, SD and inter-quartile range. For a given food or food group, the number of portions weighed varied from 5 to 210 portions in primary schools and between 5 and 194 portions in secondary schools.

CONCLUSIONS

The results provide a good representation of typical portion weights for different foods and food groups in primary and secondary schools in England. Portion size is one factor that determines nutrient intake. New standards for school lunches are both nutrient and food-based. Guidance on portion weights will help to ensure that pupils consume the correct balance of foods to obtain the recommended nutrient intake. The present findings complement and extend existing guidance on portion sizes for pupils in schools in England and Scotland.

Teleradiology: threat or opportunity?

The rapid advances in information technology and communication bandwidth have spawned an equally rapid development of clinical teleradiology. Current computer technology and communication capability allow easy transfer of diagnostic images, of any complexity, to any location in the world. This provides the opportunity to acquire swift primary and secondary diagnostic opinions from the remotest of locations, often at economically attractive rates, with the potential for easing the burden on hard-pressed departments of radiology. However, this comes at the potential cost of distancing the clinical radiologist from the patient, with consequent impact upon direct clinical care. As this technology advances across the world, it is vital that UK radiologists are familiar with the clinical implications, the medicolegal framework within which the field operates and the associated governance issues. This paper reviews current practice and discusses the associated risks.

Standardization of reticulocyte values in an antidoping context

The lack of standardization of reticulocyte results hinders the ability of sports authorities to recognize the telltale fluctuations over time that are typical for athletes using illegal blood doping to improve their performance. Therefore, the aim of the present study was to devise a tenable approach for antidoping authorities to quantify, instrument bias. We evaluated reticulocyte data derived during a 42-week period from 210 hospital patient blood samples measured in duplicate simultaneously on up to 11 hematology analyzers located in a single laboratory. We found that square root transformation of reticulocyte values enabled quantification of interinstrument bias by using the mean reticulocyte value of a cohort of approximately 54 subjects as a de facto calibration agent. We also demonstrated that measurement precision associated with low reticulocyte values was not inferior to that associated with higher values.

HTLV antibody screening using mini-pools

At the present time, the UK blood transfusion services do not screen blood donations for anti-HTLV. This presentation describes a pilot study to ascertain the feasibility of HTLV antibody screening using mini-pools and also provides an estimate of HTLV prevalence within our donor population in Scotland and Northern Ireland. The Abbott/Murex HTLV I/II GE80/81 ELISA was selected for the trial. Thirty confirmed HTLV positive library samples were tested at various dilutions and five were shown to be nonreactive at a dilution of 1:100. Residues of mini-pools (of up to 95 individual donations) prepared for HCV NAT testing were tested with the Abbott/Murex GE80/81 assay. Of 6666 mini-pools (equivalent to 570 609 donations) tested, six were repeatedly reactive. All six mini-pools were confirmed HTLV antibody positive by line immunoassay. Four were confirmed to be HTLV-I positive, one HTLV-II positive and one HTLV positive (unable to type). Dilutions (1:100) of the five HTLV "nonreactive" positive samples were included in each test plate and used to determine a grey-zone cut-off. Using this grey-zone system an additional six (0.09%) mini-pool samples gave repeatedly reactive grey-zone results, none of which were confirmed. The minimum Scottish/Irish HTLV donor prevalence was shown to be 1:95 000.

Inhibition of angiogenesis by a mouse sprouty protein

Sprouty negatively modulates branching morphogenesis in the Drosophila tracheal system. To address the role of mammalian Sprouty homologues in angiogenesis, another form of branching morphogenesis, a recombinant adenovirus engineered to express murine Sprouty-4 selectively in endothelial cells, was injected into the sinus venosus of embryonic day 9.0 cultured mouse embryos. Sprouty-4 expression inhibited branching and sprouting of small vessels, resulting in abnormal embryonic development. In vitro, Sprouty-4 inhibited fibroblast growth factor and vascular endothelial cell growth factor-mediated cell proliferation and migration and prevented basic fibroblast growth factor and vascular endothelial cell growth factor-induced MAPK phosphorylation in endothelial cells, indicating inhibition of tyrosine kinase-mediated signaling pathways. The ability of constitutively activated mutant Ras(L61) to rescue Sprouty-4 inhibition of MAPK phosphorylation suggests that Sprouty inhibits receptor tyrosine kinase signaling upstream of Ras. Thus, Sprouty may regulate angiogenesis in normal and disease processes by modulating signaling by endothelial tyrosine kinases.

Clinical teaching by community nurses in the Australian context

A study was conducted to explore factors that impact on the clinical teaching role of community nurses involved in the education of pre-registration nursing students. Respondents were community nurses working in the Western Sydney Area Health Service in New South Wales, Australia. A self-report questionnaire was developed to collect data. Results indicate that community nurses are interested in clinical teaching, that it is an important part of their role and that they perceive themselves to be effective clinical teachers, with the majority indicating motivation to continue developing their clinical teaching skills. Aspects of clinical teaching important to community nurses included facilitating the transition of education from theory to practice, sharing expertise, knowledge and skills and maintaining high standards of nursing practice. There was little support for the view that community nurses experienced difficulty in managing the dual teaching and practice role. Approximately a third of participants reported that being with a student on a one-to-one basis could be stressful. Strategies to assist community nurses in their clinical teaching role were identified.

Use of bovine viral diarrhoea virus as an internal control for amplification of hepatitis C virus

BACKGROUND AND OBJECTIVES

Screening for hepatitis C virus (HCV) by polymerase chain reaction (PCR) will be mandatory for screening blood and plasma donors in Europe and elsewhere. This study describes an internally controlled, highly sensitive PCR method designed for screening blood donations in pools.

MATERIAL AND METHODS

RNA extracted from bovine viral diarrhoea virus (BVDV) was used as an internal control to monitor the efficiency of extraction, reverse transcription and amplification steps in HCV PCR.

RESULTS

Sensitivity of PCR for single molecules of HCV in the presence of 33 genome equivalents of BVDV RNA was achieved by reducing the efficiency of BVDV amplification. BVDV could be recovered at high efficiency from large volume pools (2-5 ml) by ultracentrifugation and by the NucliSens extraction method.

CONCLUSION

Detection of BVDV validates the extraction, reverse transcription and amplification methods used for HCV detection in plasma pools and provides valuable quality assurance for negative results.

Community-level determinants of child growth in an Indonesian tea plantation

OBJECTIVES

The paper presents the results of an ecological-economic approach to identifying community-level factors that influence the physical growth of young children.

DESIGN

A cross-sectional design was used to obtain both the anthropometry and the ecological-economic data.

SETTING

The sites were 24 communities located in a tea plantation near Bandung, West Java, Indonesia.

SUBJECTS

415 children between the ages of 6 and 18 months.

METHODS

Epidemiological and ethnographic methods were used to measure community infrastructure and services related to child growth. Anthropometry was used to measure child growth. Econometric methods, including probit and ordinary least squares regression, were used to analyze the effect of community-level factors on child growth.

RESULTS

Community vaccination programs, child care services, environmental sanitation and latrines were associated with better child growth. We concluded that community-level goods and services substantially contributed to health in early childhood.

High prevalence of hepatitis G virus infection in multiply transfused children with thalassaemia

We investigated the prevalence of hepatitis G virus (HGV) RNA in relation to the frequency of blood transfusions in thalassaemic children and in volunteer blood donors in Thailand. Furthermore, we studied the frequency of coinfection with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) as well as a possible relationship to the alanine aminotransferase (ALT) status of the blood samples, taken at random from thalassaemic children who have received multiple blood transfusions and from volunteer blood donors. The results show detectable HGV-RNA in 32.6% of transfusion patients and in 5% of blood donors. The prevalence of HGV-RNA peaked between the 11th and 50th transfusion. The relationship between HGV infection and ALT status was not statistically relevant.

A combined management protocol for patients with coagulation disorders infected with hepatitis C virus

The case notes of 394 adults with bleeding disorders registered at our centre together with those of the 72 patients who had died since 1971 were reviewed. 36/72 deceased patients had evidence of HCV infection. Liver decompensation was present at time of death in six. 274 (70%) of the currently registered patients had received factor concentrate or cryoprecipitate and 174 of these were screened for HCV infection. 76% of tested patients were RIBA positive. 87% of RIBA-positive patients were RT-PCR positive. 50 RIBA-positive patients, including nine who were HIV infected, have undergone percutaneous liver biopsy following appropriate factor infusion with no complication. The biopsy was assessed using a Histological Activity Index (HAI) ranging from 0 to 13. Patients with HAI > or = 6 were offered treatment with interferon. Patients with HAI < 6 were followed up with a view to re-biopsy in 2-3 years to assess progression. The median HAI was 4.5 (range 0-10) with HAI > or = 6 in 13 cases (27%). HAI was not correlated with duration of infection. haemophilia severity. RT-PCR status. HIV status or HCV genotype. Liver biopsy, a safe procedure in our hands, is an important investigation in HCV-infected patients to assess suitability for interferon therapy.

Direct association of Grb2 with the p85 subunit of phosphatidylinositol 3-kinase

Phosphatidylinositol 3-kinase (PI 3-kinase) has been shown to play a key role in growth factor signaling pathways, although its signaling mechanism has not been fully elucidated. Using the yeast interaction trap system, we have identified Grb2 as a PI 3-kinase interacting protein. Our experiments demonstrate that p85, the regulatory subunit of PI 3-kinase, interacts with Grb2 in vivo, and this interaction is independent of growth factor stimulation. The direct association between Grb2 and p85 was reconstituted in vitro with glutathione S-transferase fusion proteins. Domain analyses and peptide competition indicate that the association is mediated by the SH3 domains of Grb2 and the proline-rich motifs of p85 and that only one SH3 domain is required for minimal binding. The interaction does not displace the catalytic subunit of PI 3-kinase but is exclusive of Sos. Signaling through PI 3-kinase, therefore, may involve the ubiquitous adapter Grb2, which serves as a convergence point for multiple pathways.

Signaling through CD19 activates Vav/mitogen-activated protein kinase pathway and induces formation of a CD19/Vav/phosphatidylinositol 3-kinase complex in human B cell precursors

The B cell-specific cell surface molecule CD19 plays a role in regulating immunoglobulin (Ig) receptor signaling, and cross-linking CD19 activates several signaling molecules in mature human B cells. In surface Ig-negative B cell precursors, a protein tyrosine kinase (PTK)-dependent homotypic aggregation response can be triggered by cross-linking CD19. In the current study, we examined the outcome of PTK-mediated signal transduction following CD19 cross-linking on surface Ig negative and surface Ig positive B cell lines, as well as freshly isolated surface Ig-negative B cell precursors. PTK activation resulted in the tyrosine phosphorylation of multiple protein substrates and peaked at 0.5-1 min following CD19 cross-linking in all B-lineage cells examined. One of the tyrosine-phosphorylated substrates was identified as the hematopoietic-specific protein Vav, a guanine nucleotide exchange factor that activates the Ras pathway. Evidence consistent with Ras pathway activation was also demonstrated by MEK activation and subsequent phosphorylation of a MAP kinase fusion protein. CD19 cross-linking, sequential immunoprecipitation, and Western blotting revealed that: (a) Vav becomes associated with CD19, (b) phosphatidylinositol 3-kinase (PI 3-kinase) becomes associated with CD19, and (c) PI 3-kinase becomes associated with Vav. No such physical interaction occurred following control IgG1 cross-linking or cross-linking of class I major histocompatability complex cell surface molecules. Coupled with a previous report (Tuveson, D.A., Carter, R.H., Soltoff, S.P., and Fearon, D.T. (1993) Science 260, 986-988), our data support a model in which CD19 cross-linking induces the formation of a signaling complex that leads to the activation of two pathways involving Ras and PI 3-kinase.