Core Outcome Set for Reporting Outcomes of Interventions for Velopharyngeal Dysfunction: Final Results of the COS-VPD Initiative

OBJECTIVE

To date, the recording of outcomes of interventions for velopharyngeal dysfunction (VPD) has not been standardized. This makes a comparison of results between studies challenging. The aim of this study was to develop a core outcome set (COS) for reporting outcomes in studies examining the management of VPD.

DESIGN

A two-round Delphi consensus process was used to develop the COS.

PATIENTS, PARTICIPANTS

The expert Delphi panel comprised patients and caregivers of patients with VPD, surgeons and speech and language therapists specializing in cleft palate, and researchers with expertise in VPD.

INTERVENTIONS

A long list of outcomes was derived from the published literature. In each round of a Delphi survey, participants were asked to score outcomes using the Grading of Recommendations, Assessment, Development, and Evaluations scale of 1 to 9, with 1 to 3 labeled "not important," 4 to 6 labeled "important but not critical," and 7 to 9 labeled "critical."

MAIN OUTCOME MEASURE

Consensus criteria were specified a priori. Outcomes with a rating of 75% or more of the panel rating 7 to 9 and 25% or fewer rating 1 to 3 were included in the COS.

RESULTS

A total of 31 core outcomes were identified from the Delphi process. This list was condensed to combine topic areas to produce a final COS of 10 outcomes, including both processes of care and patient-reported outcomes that should be considered for reporting in future studies of VPD.

CONCLUSIONS

Implementation of the COS-VPD will facilitate consistency of outcomes data collection and comparison of results across studies.

Protocol for the development of a core outcome set for reporting outcomes of management of velopharyngeal dysfunction

INTRODUCTION

Velopharyngeal dysfunction (VPD) is present in up to 40% of patients following cleft palate repair. Children with VPD display hypernasal speech, nasal air emission and are at a high risk for developing articulation disorders. The overall result is decreased intelligibility and acceptability of speech, as well as significant functional and social impairments. Although there are several surgical approaches for the management of children with VPD, standard treatment protocols have not been well defined. There is a need for a core outcome set (COS) to reduce outcome reporting bias and heterogeneity across studies of VPD. The COS-VPD Initiative is an international effort to establish a COS for the reporting of studies of the management of VPD.

METHODS AND ANALYSIS

The study has been developed according to the Core Outcome Set-STAandards for Development standards for the design of a COS study and will be carried out according to the guidance of the Core Outcome Measures in Effectiveness Trials (COMET) initiative. A long list of clinical and patient-reported outcomes will be identified from a systematic review of the literature. A two-stage Delphi consensus process will be used to refine this list into a COS. An international panel of key stakeholders including patients, parents and multidisciplinary clinical and academic experts will be invited to participate in this process. Consensus criteria will be specified a priori and the steering group will ratify the final COS.

ETHICS AND DISSEMINATION

The study has ethical approval through Children's Health Ireland at Crumlin Research and Ethics Committee, Ref: GEN/683/18. The study is registered with the COMET Initiative (http://www.cometinitiative.org/studies/details/1146?result=true). The COS will be disseminated by publication in the peer-reviewed literature, presentation at international research meetings and distribution to patient-representative organisations. This will facilitate the application of the COS in future studies of the management of VPD.

Clinicopathological case: headache and systemic inflammatory illness—Occam vs Hickam

A 63-year-old woman presented with a sudden headache, which persisted and subsequently changed in character. Over time, constitutional features developed, leading to an unexpected diagnosis. This report documents the clinicopathological conference at the Association of British Neurologists Annual Meeting 2019.

Monitoring the hepatitis C epidemic in England and evaluating intervention scale-up using routinely collected data

In England, 160 000 individuals were estimated to be chronically infected with hepatitis C virus (HCV) in 2005 and the burden of severe HCV-related liver disease has increased steadily for the past 15 years. Direct-acting antiviral treatments can clear infection in most patients, motivating HCV elimination targets. However, the current burden of HCV is unknown and new methods are required to monitor progress. We employed a Bayesian back-calculation approach, combining data on severe HCV-related liver disease and disease progression, to reconstruct historical HCV incidence and estimate current prevalence in England. We explicitly modelled infections occurring in people who inject drugs, the key risk group, allowing information on the size of this population and surveillance data on HCV prevalence to inform recent incidence. We estimated that there were 143 000 chronic infections in 2015 (95% credible interval 123 000-161 000), with 34% and 54% in those with recent and past injecting drug use, respectively. Following the planned scale-up of new treatments, chronic infections were predicted to fall to 113 400 (94 900-132 400) by the end of 2018 and to 89 500 (71 300-108 600) by the end of 2020. Numbers developing severe HCV-related liver disease were predicted to fall by at least 24% from 2015 to 2020. Thus, we describe a coherent framework to monitor progress using routinely collected data, which can be extended to incorporate additional data sources. Planned treatment scale-up is likely to achieve 2020 WHO targets for HCV morbidity, but substantial efforts will be required to ensure that HCV testing and patient engagement are sufficiently high.

Translocation of the novel cytokine HMGB1 to the cytoplasm and extracellular space coincides with the peak of clinical activity in experimentally UV-induced lesions of cutaneous lupus erythematosus

HMGB1 is a pro-inflammatory cytokine that together with TNF-α and IL-1β is involved in the pathogenesis of spontaneously occurring skin lesions in lupus erythematosus. The purpose of the present study was to explore the sequence of events in HMGB1, TNF-α and IL-1β expression under development and resolution of experimentally induced CLE lesions. The study involved investigation of 38 serial skin biopsies acquired from photoprovoked skin lesions of nine CLE patients, using immunohistochemical staining of tissue sections. In biopsies from the clinically most active phase of skin involvement extracellular, secreted HMGB1 and increased cytoplasmic HMGB1 were found, as compared with the late and fading lesions or non-lesional skin. Besides HMGB1, increased expression of TNF-α and IL-1β was observed in dermal infiltrates of the induced CLE lesions. These cytokines were however not upregulated in all lesions, and increased expression of IL-1β was seen predominantly in late biopsies.

In conclusion, extracellular and cytoplasmic HMGB1 coincides with the clinically most active phase of photoinduced lesions of cutaneous lupus, and suggests that HMGB1 is an important factor in the inflammatory autoimmune process of CLE. HMGB1 can induce expression of TNF-α and IL-1β, and formation of a pro-inflammatory loop between HMGB1, TNF-α, and IL-1β may be responsible for the prolonged and sustained inflammation in CLE. Lupus (2007) 16, 794—802.

LACC1 polymorphisms in inflammatory bowel disease and juvenile idiopathic arthritis

The function of the Laccase domain-containing 1 (LACC1) gene is unknown, but genetic variation at this locus has been reported to consistently affect the risk of Crohn's disease (CD) and leprosy. Recently, a LACC1 missense mutation was found in patients suffering from monogenic forms of CD, but also systemic juvenile idiopathic arthritis. We tested the hypothesis that LACC1 single nucleotide polymorphisms (SNPs), in addition to CD, are associated with juvenile idiopathic arthritis (JIA, non-systemic), and another major form of inflammatory bowel disease, ulcerative colitis (UC). We selected 11 LACC1 tagging SNPs, and tested their effect on disease risk in 3855 Swedish individuals from three case-control cohorts of CD, UC and JIA. We detected false discovery rate corrected significant associations with individual markers in all three cohorts, thereby expanding previous results for CD also to UC and JIA. LACC1's link to several inflammatory diseases suggests a key role in the human immune system and justifies further characterization of its function(s).

How to Motivate Patients with Rheumatoid Arthritis to Quit Smoking

OBJECTIVE

Seropositive rheumatoid arthritis (RA) is strongly linked to cigarette smoking, and smoking cessation is an essential step in RA management. Our objectives were to develop RA and smoking awareness materials and to evaluate the influence of the materials on awareness about the links between RA and smoking and on motivation to quit smoking.

METHODS

A group of patients with seropositive RA in Fife, Scotland, were telephoned before the campaign, and the results of the precampaign questionnaire were used to develop the image for the campaign. After the campaign a second group of patients were questioned to ascertain the effect of the campaign.

RESULTS

The 320 patient responses to the precampaign questionnaire revealed that many ex-smokers with RA had quit when they developed a known smoking-related disease such as emphysema. This concept was used to develop an image illustrating that RA is a smoking-related disease. The campaign was launched in Fife in 2011. The postcampaign questionnaire involving 380 patients revealed that there was 21% higher awareness of a link between RA and smoking and 45% higher awareness that smoking could interfere with treatment of RA. In total, 13/75 smokers who had cut down since the campaign had been influenced by the new information.

CONCLUSION

The new materials have successfully increased patients' knowledge of the link between RA and smoking and the effect of smoking on RA therapy. RA smokers' attitudes to smoking may have been affected by the campaign.

Retrospective cohort study of liver transplantation in the United Kingdom between 1994 and 2010: the impact of hepatitis C infection

BACKGROUND

Liver transplantation is an important and established treatment option for chronic hepatitis C virus (HCV) related end-stage liver disease (HCV-related ESLD). This study describes trends in elective liver transplantation among persons with HCV-related ESLD.

STUDY DESIGN

Retrospective cohort.

METHODS

Analyses of United Kingdom (UK) Transplant Registry data for the period 1994 to 2010, with follow-up information extending to 2011.

RESULTS

Annual registrations for liver transplantation increased linearly and alcoholic liver cirrhosis (2075, 24%) and HCV-related ESLD (1213, 14%) were the most common indications. HCV-related ESLD patients were mainly aged 40-49 years (32%) and 50-59 years (43%); males (76%); and of white ethnicity (74%). Overall, 75% (956/1213) received a liver transplant with a linear increase over the period (OR 1.11, 95% CI 1.08, 1.13). Pre transplant mortality was unchanged (adjusted OR 1.0, 95% CI 0.96, 1.05) and post-transplant mortality decreased in both HCV-related (adjusted OR 0.77, 95% CI 0.68, 0.88) and non-HCV-related ESLD (adjusted OR 0.82, 95% CI 0.75, 0.89) patients.

CONCLUSION

The increase in demand for and receipt of liver transplants among persons with HCV-related ESLD requires coordinated efforts to increase not only organ donation, but investment in HCV prevention programmes and improved access to hepatitis C treatment services.

IL-1β/HMGB1 complexes promote The PGE2 biosynthesis pathway in synovial fibroblasts

PGE₂ is a potent lipid mediator of pain and oedema found elevated in RA. Microsomal prostaglandin E synthase-1 (mPGES-1) is a terminal enzyme of the PGE₂ pathway inducible by proinflammatory cytokines. mPGES-1 is markedly upregulated in RA synovial tissue despite antirheumatic treatments, suggesting that multiple inflammatory stimuli contribute to its induction. High-mobility group box chromosomal protein 1 (HMGB1) is known to induce inflammation both by direct interaction with TLR4 and by enhancement of other proinflammatory molecules signalling, through complex formation. The high expression of extracellular HMGB1 within the inflamed synovium, implies its pro-arthritogenic role in RA. We aimed to investigate the effects of IL-1β/HMGB1 complexes on mPGES-1 and other enzymes of the PGE₂ pathway in synovial fibroblasts (SFs) from patients with arthritis. Furthermore, we studied the effect of COX-2 inhibition and IL-1RI antagonism on prostanoid and cytokine production by SFs. Stimulation of SFs with HMGB1 in complex with suboptimal amounts of IL-1β significantly increased mPGES-1 and COX-2 expressions as well as PGE₂ production, as compared to treatment with HMGB1 or IL-1β alone. Furthermore, NS-398 reduced the production of IL-6 and IL-8, thus indicating that IL-1β/HMGB1 complexes modulate cytokine production in part through prostanoid synthesis. Treatment with IL-1RA completely abolished the induced PGE₂ and cytokine production, suggesting an effect mediated through IL-1RI. IL-1β/HMGB1 complexes promote the induction of mPGES-1, COX-2 and PGE₂ in SF. The amplification of the PGE₂ biosynthesis pathway by HMGB1 might constitute an important pathogenic mechanism perpetuating inflammatory and destructive activities in rheumatoid arthritis.

Improved hepatitis C treatment response in younger patients: findings from the UK HCV National Register cohort study

In a cohort of 272 treatment-naive individuals with chronic hepatitis C infection acquired on a known date who were enrolled in the UK HCV National Register, a progressive improvement in response to treatment was found with the evolution of antiviral therapies from 20% (25/122) for interferon monotherapy to 63% (55/88) for pegylated interferon+ribavirin therapy. Multivariable analysis results showed increasing age to be associated with poorer response to therapy [odds ratio (OR) 0·84, 95% confidence interval (CI) 0·72-0·99, P=0·03] whereas time since infection was not associated with response (OR 0·93, 95% CI 0·44-1·98, P=0·85). Other factors significantly associated with a positive response were non-type 1 genotype (P<0·0001) and combination therapies (P<0·0001). During the first two decades of chronic HCV infection, treatment at a younger age was found to be more influential in achieving a sustained viral response than treating earlier in the course of infection.

Spontaneous loss of hepatitis C virus RNA from serum is associated with genotype 1 and younger age at exposure

A variety of factors have been associated with spontaneous loss of hepatitis C virus (HCV)-RNA from serum, including infecting HCV type, although results are conflicting. This study aimed to investigate further whether infecting HCV type was linked to spontaneous loss of HCV-RNA. Serum samples from 321 untreated HCV antibody positive patients presenting at the Hepatology clinic at Addenbrooke's Hospital, Cambridge between 2004 and 2007 were tested. These individuals were classified either as HCV antibody and HCV-RNA positive (viremic, n = 219) or HCV antibody positive and repeatedly HCV-RNA negative (non-viremic, n = 102). Infecting HCV type was identified by genotyping (viremic) or serotyping (non-viremic). Binomial regression analysis investigated the independent effect of HCV type on spontaneous loss of HCV-RNA from serum by comparing the two groups. Ninety-one percent of patients were found to be either genotype 1 or genotype 3. The prevalence of type 1 infection was greater among non-viremic (64.5%) than viremic individuals (45%). After controlling for the effects of potential confounding factors, multivariable analyses showed that individuals with type 1 infections were more likely to be non-viremic than genotype 3 infections (RR = 2.07; 95% CI: 1.25, 3.43; P = 0.005). Individuals infected at an older age were also less likely to become HCV-RNA negative spontaneously (RR = 0.42 comparing those infected at ≥20 years of age against those infected at <20 years of age, 95% CI: 0.25, 0.72; P = 0.002). In conclusion, the results suggest that HCV genotype 1 infections are more likely than genotype 3 infections to become spontaneously non-viremic, as are infections acquired at younger age.

A national sample of individuals who acquired hepatitis C virus infections in childhood or adolescence: risk factors for advanced disease

OBJECTIVES

To describe hepatitis C virus (HCV)-related liver disease in a national cohort of patients who acquired their infections in childhood or adolescence and to assess risk factors for progressive disease and response to antiviral therapy.

PATIENTS AND METHODS

Demographic, laboratory, and clinical outcome data on 246 individuals who acquired HCV infection before the age of 16 years were extracted from the UK HCV National Register database. Logistic regression analysis was used to investigate the independent effects of sex, age, duration and route of infection, and comorbidity on histological stage of liver disease.

RESULTS

Median ages at enrollment and follow-up were 14.0 years (range, 2.2-29.6 years) and 19.2 years (range, 2.3-35.5 years), respectively. Mean duration of infection at enrollment was 8.5 years (standard deviation [SD], 3.3 years), and mean duration of follow-up was 4.5 years (SD, 4.5 years). Fifty-nine (24%) had persistently abnormal liver aminotransferase levels; 22% reported physical signs and symptoms of liver disease. Among 123 individuals with liver biopsies, 117 (95%) had abnormal histological findings. Ninety-eight individuals had biopsies referred for independent blind scoring; median Ishak grade and stage scores were 3 and 1, respectively. Presence of comorbidities (odds ratio [OR], 7.19; 95% CI, 2.00-26.17; P = 0.003) and female sex (OR, 0.31; 95% CI, 0.10-1.00; P = 0.05) were independently associated with histological stage scores greater than the median. A total of 110 individuals received antiviral therapy; 47% achieved a sustained response.

CONCLUSIONS

HCV-related liver disease in those who acquired the infection in childhood or adolescence was mild for most, although comorbidity and female sex were associated with more advanced disease. Antiviral therapy in childhood or adolescence successfully eradicates the virus for many patients.

The burden of hepatitis C in England

In England, a large number of individuals are infected with the hepatitis C virus (HCV) and may develop future liver complications, such as decompensated cirrhosis and hepatocellular carcinoma (HCC). Estimates of the magnitude of this future burden are required to plan healthcare resources. We have estimated past incidence of HCV infection in England and predict future burden of end-stage liver disease in the HCV-infected population. A model of the natural history of HCV as a series of disease stages was constructed. A back-calculation approach was performed, using the natural history model and data on annual HCC deaths in England from 1996 to 2004 with mention of HCV and hospital episode statistics for end-stage liver disease with HCV. The number of HCV-infected people living with compensated cirrhosis is predicted to rise from 3705 [95% credible interval (CrI): 2820-4975] in 2005 to 7550 (95% CrI: 5120-11,640) in 2015. The number of decompensated cirrhosis and/or HCC cases is also predicted to rise, to 2540 (95% CrI: 2035-3310) by 2015. HCV incidence increased during the 1980s, with an annual incidence of 12 650 (95% CrI: 6150-26,450) by 1989. HCV-related cirrhosis and deaths from HCC in England are likely to increase dramatically within the next decade. If patients are left undiagnosed and untreated, the future burden of the disease on healthcare resources will be substantial.

Does the clinical outcome of hepatitis C infection vary with the infecting hepatitis C virus type?

Whether differences in the natural history of hepatitis C virus (HCV) can be explained by differences in the infecting HCV type is unknown. The aim of this study was to investigate whether the HCV type might influence the clinical outcome of infection. Study serum samples were assembled from 749 individuals enrolled into the UK HCV National Register from which data on clinical outcomes were extracted. HCV-RNA-positive specimens were genotyped and HCV-RNA-negative specimens serotyped. Logistic regression analysis was used to investigate the independent effect of HCV type on viral clearance by comparing patients who were HCV RNA negative (n = 86) with those who were HCV RNA positive (n = 508). The same method was used to investigate whether HCV type was associated with histological stage of liver disease. The prevalence of HCV type 1 among those who cleared infection was 69% and among those who remained HCV RNA positive was 51%: Type 1 infections were more likely to be HCV RNA negative than non-1 types (OR 0.47, 95% CI 0.29-0.78, P = 0.003). Type 1 infections were also more likely to be associated with histological stage scores above the median when compared with non-1 types (OR 2.03, 95% CI 1.07-3.83, P = 0.03). In conclusion, HCV type 1 infection was more often HCV RNA negative, suggesting that spontaneous clearance may occur more commonly with this type. Among the RNA-positive infections, type 1 infection may be more aggressive than types 2/3.

Estimated progression rates in three United Kingdom hepatitis C cohorts differed according to method of recruitment

OBJECTIVES

To estimate hepatitis C virus (HCV) progression rates between disease stages prior to cirrhosis, using data from liver biopsies in three observational cohorts. To demonstrate how the method of cohort recruitment can influence the estimation of HCV-progression rates.

STUDY DESIGN AND SETTING

Data came from three United Kingdom observational cohorts, assembled from different referral sources. In total, 987 HCV-infected patients with an estimated (or known) date of infection and at least one histologically scored liver biopsy were eligible for inclusion in the analysis. Liver biopsy scores were used to determine the stage of HCV-related liver disease. A three-state continuous time Markov model was used to estimate covariate-specific average probabilities of progression of disease.

RESULTS

After adjusting for confounders, considerably different rates of disease progression were estimated in the three cohorts. For a group of patients with the same demographics, the estimated 20-year probability of progression to cirrhosis was 12% (95% confidence interval CI = 6-22) in a hospital-based cohort, 6% (95% CI = 3-13) in a posttransfusion cohort, and 23% (95% CI = 14-37) in a cohort recruited from a tertiary referral center.

CONCLUSION

Researchers using estimates of disease progression should be aware that the method of cohort recruitment has considerable influence on the progression rates that are derived.

Pathways of care and resource utilization in a national cohort of patients with transfusion-acquired hepatitis C

The Hepatitis C Strategy and Action Plan for England recommend that all individuals testing positive for hepatitis C virus (HCV) should be referred to a specialist centre for assessment and care. One key aim is to reduce the number of people progressing to liver disease and therefore reduce the associated costs. The aims of this paper are to describe the care pathways and evaluate resource utilization in a cohort of 826 patients with transfusion-acquired hepatitis C enrolled in the HCV national register. We reviewed data extracted from patient notes to establish pathways of care since HCV-positive diagnosis through to May 2002, and to document all treatment, liver biopsy and hospital usage for each patient. Type of care was classified into specialist-interest in HCV-related care, other-hospital care or general practitioner (GP)-led care. Over 70% of patients were referred to specialist care following HCV diagnosis. Patients who were older or who had normal liver function were less likely to be referred to specialist-care. Between first diagnosis and May 2002, no patients were referred from GP to specialist-care. Less than half of this cohort had undergone liver biopsy and only 18% had been treated. Younger patients and those with abnormal liver function were more likely to have undergone liver biopsy and to have received treatment. Analysis of care histories of patients with transfusion-acquired hepatitis C suggest that changes are needed in the care and management of patients with HCV infection, if the recommendations of the HCV strategy and action plan are to be fully implemented.

CNI-1493, an inhibitor of proinflammatory cytokines, retards cartilage destruction in rats with collagen induced arthritis

OBJECTIVE

To investigate if administration of CNI-1493, an inhibitor of the synthesis of proinflammatory cytokines and NO, protects against development of joint destruction in collagen induced arthritis (CIA) in rats.

METHODS

In a placebo controlled experiment, CNI-1493 was given once daily intraperitoneally after onset of clinical arthritis in DA rats. Disease progression was studied by clinical scoring of arthritis, serial measurement of serum levels of COMP, and histological examination of joints.

RESULTS

Clinical signs of arthritis were significantly reduced in the CNI-1493 treated group of rats in comparison with the placebo treated group. Histological examinations of paws demonstrated a significant reduction of cartilage destruction in the CNI-1493 treated group, but marked destruction of cartilage in the placebo group. Serum levels of COMP increased in the placebo group, whereas in the CNI-1493 treated group levels were low and decreased significantly during the observation time.

CONCLUSIONS

Treatment with CNI-1493 provides efficient protection against synovial inflammation and cartilage destruction when used therapeutically in CIA. The protective effect against cartilage destruction can be monitored by measuring serum COMP. These observations make CNI-1493 an attractive candidate for therapeutic studies in human arthritis, and COMP an attractive serum marker for monitoring joint protective effects.

Inhibition by Artocarpus tonkinensis of the Development of Collagen-Induced Arthritis in Rats

Extracts of the leaves and roots from the tree Artocarpus tonkinensis A Cheval (family Moraceae) are used in traditional Vietnamese medicine in order to treat backache as well as rheumatic joint diseases. We prepared an ethyl acetate (EtOAc) extract from this plant and tested its anti-inflammatory properties in an experimental arthritis model, collagen-induced arthritis (CIA). CIA was induced in Dark Agouti rats by means of immunization with collagen type II (CII) emulsified in incomplete Freund's adjuvant. Starting at the day of immunization, the rats were treated daily with intraperitoneal injections of Artocarpus extract. Arthritis progression was measured by means of clinical scoring of paws and anti-CII antibody titres were measured by means of ELISA. In vitro, lymph node (LN) cell cultures were treated with Artocarpus extract and the apoptosis-inducing effect was determined with FACS staining by using annexin V and propidium iodide as well as the TUNEL method. Treatment of the rats with Artocarpus extract decreased arthritis incidence and severity and delayed disease onset. When treatment was started after the onset of arthritis, a tendency towards arthritis amelioration was observed. In vitro, Artocarpus extract acted as a T-cell modulator, inhibiting mitogen-induced T-cell proliferation and inducing apoptosis of activated LN-derived lymphocytes. Thus, we have demonstrated that an EtOAc extract of Artocarpus, a plant traditionally used in Vietnamese folk medicine for treating arthritic conditions, has beneficial effects in an experimental arthritis model. This effect is likely to be T cell-dependent and mediated through apoptosis induction in activated cells.

RAGE is the major receptor for the proinflammatory activity of HMGB1 in rodent macrophages

Abstract High-mobility group box chromosomal protein 1 (HMGB1) is a protein with both intranuclear functions and extracellular cytokine-like effects. In this report, we study possible candidate receptors for HMGB1 on macrophages (Mphi) and define pathways activated by HMGB1 binding. Bone marrow Mphi were prepared from Dark Agouti (DA) rats and stimulated in vitro with HMGB1. The kinetics of tumour necrosis factor (TNF) production, NO production, activation of p38 mitogen-activated protein kinase (MAPK), p44/42 MAPK- and SAPK/JNK-signalling pathways, nuclear translocation of nuclear factor kappa B (NF-kappaB) and HMGB1-induced upregulation of major histocompatibility complex (MHC) class II and CD86 were analysed. Mphi from interleukin (IL)-1 receptor type I-/-, Toll-like receptor 2 (TLR2-/-) and RAGE-/- mice were used to investigate the role of these receptors in HMGB1 signalling. HMGB1 induced TNF and NO production by Mphi, phosphorylation of all investigated MAP kinase pathways and NF-kappaB translocation, and expression of MHC class II was increased. Mphi from RAGE-/- mice produced significantly lower amounts of TNF, IL-1beta and IL-6, while IL-1RI-/- and TLR2-/- Mphi produced cytokine levels comparable with wildtype controls in response to HMGB1 stimulation. We conclude that HMGB1 has the potential to induce a proinflammatory phenotype in Mphi, with RAGE as the major activation-inducing receptor.

Alteration of an Autoantigen by Chlorination, a Process Occurring During Inflammation, Can Overcome Adaptive Immune Tolerance

Autoimmune diseases are characterized by chronic inflammation in target organs and immunoreactivity towards one or multiple autoantigens. Several potential mechanisms of tolerance breaking have been postulated, one being inflammation-associated events. We have investigated whether chlorination of an autoantigen can lead to disruption of self-tolerance. Chlorination of antigens might occur during inflammation via the granulocyte-specific, myeloperoxidase-catalysed conversion of hydrogen peroxide to hypochlorous acid (HOCl). HOCl, being a strong oxidant, reacts with proteins both within cellular phagosomes and in the immediate extracellular environment. By immunizing Lew.1AV1 rats with chlorinated or unmodified rat serum albumin (RSA), we could detect tolerance-breaking effects of chlorination. RSA is a systemic autoantigen in rat not inducing antibody production upon immunization in its unmodified form. Rats immunized with chlorinated RSA (RSA-Cl) developed high titres of immunoglobulin G (IgG) specific for RSA-Cl which cross-reacted with native RSA. T cells reactive with both RSA-Cl and RSA were detected by [(3)H]-thymidine incorporation. We hence speculated that immunological tolerance established for unmodified proteins, during certain circumstances such as inflammation, might be broken by induced protein chlorination. T cells specific for the chlorinated protein can confer help to B cells recognizing both the chlorinated and the native form of the protein, leading to the formation of high-affinity autoreactive antibodies and possibly autoimmune disease.

Clinical course of hepatitis C virus during the first decade of infection: cohort study

OBJECTIVE

To determine the clinical course of hepatitis C virus in the first decade of infection in a group of patients who acquired their infections on a known date.

DESIGN

Cohort study.

SETTING

Clinical centres throughout the United Kingdom.

PARTICIPANTS

924 transfusion recipients infected with the hepatitis C virus (HCV) traced during the HCV lookback programme and 475 transfusion recipients who tested negative for antibodies to HCV (controls).

MAIN OUTCOME MEASURES

Clinical evidence of liver disease and survival after 10 years of infection.

RESULTS

All cause mortality was not significantly different between patients and controls (Cox's hazards ratio 1.41, 95% confidence interval 0.95 to 2.08). Patients were more likely to be certified with a death related to liver disease than were controls (12.84, 1.73 to 95.44), but although the risk of death directly from liver disease was higher in patients than controls this difference was not significant (5.78, 0.72 to 46.70). Forty per cent of the patients who died directly from liver disease were known to have consumed excess alcohol. Clinical follow up of 826 patients showed that liver function was abnormal in 307 (37.2%), and 115 (13.9%) reported physical signs or symptoms of liver disease. Factors associated with developing liver disease were testing positive for HCV ribonucleic acid (odds ratio 6.44, 2.67 to 15.48), having acquired infection when older (at age > or = 40 years; 1.80, 1.14 to 2.85), and years since transfusion (odds ratio 1.096 per year, 1.00 to 1.20). For patients with severe disease, sex was also significant (odds ratio for women 0.38, 0.17 to 0.88). Of the 362 patients who had undergone liver biopsy, 328 (91%) had abnormal histological results and 35 (10%) of these were cirrhotic.

CONCLUSIONS

Hepatitis C virus infection did not have a great impact on all cause mortality in the first decade of infection. Infected patients were at increased risk of dying directly from liver disease, particularly if they consumed excess alcohol, but this difference was not statistically significant.

Binding, pharmacological and immunological profiles of the delta-selective opioid receptor antagonist HS 378

HS 378 is a recently developed indolomorphinan with high selectivity and antagonist potency at the delta-opioid receptor. The present study was performed to characterize the opioid binding properties and pharmacological and immunological activity of HS 378 and to compare them with those of two well-known delta-opioid receptor antagonists, naltrindole (NTI) and naltriben (NTB). In vitro opioid receptor binding profiles were determined in rat brain homogenates. HS 378 showed 4.7- and 2.4-fold higher mu/delta selectivity compared to NTI and NTB, respectively. In the [35S]GTPgammaS functional assay carried out in cell lines expressing cloned human opioid receptors, HS 378 was found to be a pure delta-opioid receptor antagonist. In vitro, exposure of HS 378 resulted in an apparent dose-related suppression of concanavalin A induced rat T-lymphocyte proliferation with an IC50 value of 0.54 microM. NTI showed also immunosuppression with an IC50 value of 6.93 microM, whereas NTB had no effect. The IC50 of HS 378 was 13 times lower than that of NTI and 8 times higher than that of cyclosporin A. Taken together, our findings indicate that the small molecule HS 378 has properties that may be of therapeutic value in the setting of human inflammatory diseases.

The HCV National Register: towards informing the natural history of hepatitis C infection in the UK

The aim of this paper is to describe the development of a national hepatitis C register and the completeness of the data it contains. This is a descriptive report of the structure and function of the register, including case definitions, registration and follow-up procedures, and methods used to maximize data quality and to obtain comparative data sources. The register contains data on HCV-infected individuals who acquired their infections on a known date and by a known route; to date all are transfusion recipients identified during the UK lookback exercise, who tested positive or indeterminate for anti-HCV after receiving 'infected' blood issued before the introduction of routine testing of the blood supply for anti-HCV. By 31 December 1999, 871 (87%) of 996 eligible transfusion recipients had been registered, and 984 (99%) flagged in the NHS Central Registers. Registered patients had been infected for an average of 11.1 years (SEM 0.1); around half were being cared for by clinicians with a specialist interest in liver disease. Except for the information on tobacco use, current alcohol use, and hepatitis B status, data were more than 80% complete, and for most variables, more than 90% complete. The consistency of data abstraction was found to be 98% (SEM 0.5). In conclusion, the Register contains high quality anonymised data on one of the largest cohorts of individuals with HCV infections acquired on a known date and by a known route. It could serve as a model for other chronic disease registers; developers may find the structure, design, and methodological issues addressed useful.

Do the psychosocial and behavioral changes that accompany motherhood influence the impact of pregnancy on long-term weight gain?

The aim of the present study was to assess whether the psychosocial and behavioral changes that occur during and after pregnancy influence long-term weight gain. The study examined 74 mothers enrolled in the Antenatal Care (ANC) Project (a randomized controlled trial of antenatal care based in South London), all of whom had volunteered to take part in a subsequent follow-up study. Data on body weight at the beginning of pregnancy; lifestyle and behavior during pregnancy; antenatal care and obstetric history; together with measures of postnatal depression and parenting stress following pregnancy were taken from the existing ANC Project database. Additional measurements of height and weight together with information on a variety of lifestyle changes and psychosocial characteristics, were gathered during semi-structured interviews at each mother's home, two and a half years after their children had been born. The results show that pregnancy-related weight gains are not simply the result of retaining weight that is gained during pregnancy, but that they also originate from gaining additional weight in the postpartum period. Mothers who felt they ate more after their children were born, had significantly greater long-term weight gains (2.78 (1.42) kg) than those who felt that they had not increased their food intake (-1.15 (0.76) kg; t = 2.49, p = 0.016). Similarly, mothers who felt they had greater access to food postpartum, had significantly greater long-term weight gains (1.70 (0.87) kg) than those who felt they did not have greater access to food (-1.37 (1.13) kg; t = 2.18, p = 0.032). There was some evidence that the lifestyle changes which accompany pregnancy and motherhood increase some women's vulnerability to eating disorder psychopathology. Mothers who felt they did less exercise after pregnancy than they did before, were also at greater risk of long-term weight gain (p = 0.028), as were mothers with low numbers of supportive individuals (p = 0.033). Neither the stress of parenting nor maternal depression were significantly associated with an increased risk of long-term weight gain (p > 0.05).

Relative importance of heritable characteristics and lifestyle in the development of maternal obesity

STUDY OBJECTIVE

To assess the relative importance of heritable characteristics and lifestyle in the development of "maternal obesity" after pregnancy.

SETTING

South east London, in the homes of mothers who had delivered their babies at either Guy's, Lewisham or St Thomas's hospitals.

PARTICIPANTS

Seventy four mothers of low antenatal risk who had been enrolled in the Antenatal Care (ANC) Project (a previous trial of antenatal care) during the first trimester of pregnancy, and who had subsequently been followed up 2.5 years after delivery.

DESIGN

Information on parental obesity, psychosocial and sociodemographic factors as well as lifestyle, was gathered during a semi-structured interview at each mother's home. Additional anthropometric and psychosocial data were taken from the existing ANC Project database. These data were used to assess the relative importance of heritable characteristics and lifestyle on changes in maternal body weight from the beginning of pregnancy to the follow up interview.

MAIN RESULTS

After adjusting for the effects of potential confounders and known risk factors for maternal obesity, women who selected larger silhouettes to represent their biological mothers were significantly more likely to have higher long term weight gains than those who selected thinner maternal silhouettes (r = 0.083, p = 0.004). Women who were less satisfied with their bodies postpartum had significantly greater long term weight gains than those women who displayed no increase in dissatisfaction with their bodies after pregnancy (r = 0.067, p = 0.010).

CONCLUSIONS

A heritable predisposition to gain weight together with changing attitudes to body size, both had an independent role in the development of maternal body weight after pregnancy. Differences in each woman's heritable predisposition to gain weight and any changes in body image that occur after pregnancy might explain why some women gain weight in association with pregnancy.

Surveillance of hepatitis B: an example of a vaccine preventable disease

The objectives of surveillance for vaccine preventable disease vary with the stage of the vaccination programme. Pre-implementation data is required to estimate the burden of disease and to decide on the appropriate vaccination strategy. Post-implementation data is required to monitor effectiveness but when high coverage is achieved surveillance must be able to accurately identify remaining pockets of susceptible persons. Sources of data include clinical and laboratory reporting. In most countries, all vaccine preventable diseases (including acute viral hepatitis) are notifiable by law. Such systems are prone to under-reporting but are usually satisfactory for monitoring trends. To encourage the rapid tracing and vaccination of contacts of acute hepatitis B, a sensitive case definition and timely reporting system are required. A clinical definition (e.g. for viral hepatitis) may be too broad, however, to assess the impact of vaccination and additional laboratory criteria may be necessary. As a country nears elimination, the predictive value of any case definition will fall and laboratory confirmation will always be required to target policy appropriately. Serological surveillance is another method for estimating disease incidence. This may be useful for hepatitis B as tests can distinguish vaccine induced immunity from natural infection and acute from prevalent cases. To monitor vaccine impact, age-coded specimens can be collected on an intermittent basis. Where the incidence is low, however, this approach, will be very expensive. Surveillance of vaccine preventable disease therefore requires flexible surveillance systems which are able to adapt to changes in incidence of infection and in control policy. The use of multiple data sources and supportive information from special studies is essential for the valid interpretation of routine data.

Are overweight women at increased risk of obesity following pregnancy?

Longitudinal studies suggest that women who already have a high BMI are at greater risk of maternal obesity than their lighter counterparts. The aim of the present study was to investigate this possibility by examining the relationship between reproductive history and maternal BMI in a community of 627 women from South Africa with a high prevalence of obesity. Standardized questionnaires were used to obtain detailed sociodemographic and behavioural information, while maternal weight and height were both measured at the time of the interview. Analysis of covariance (ANCOVA) showed that maternal age (r2 0.015, P = 0.001), smoking status (r2 0.012, P = 0.036), and social support (r2 0.011, P = 0.006) were all independently associated with maternal BMI. If overweight women were at increased risk of maternal obesity, then the positive relationship between reproductive history and maternal BMI should be enhanced in this relatively obese community, yet the ANCOVA models showed no independent association between gravidity and maternal BMI after controlling for the effects of confounding factors. Although previous longitudinal studies have found a positive association between prepregnant weight and long-term weight gain, this relationship might arise because overweight women gain more weight over a fixed period of time than normal weight women, and therefore they may appear to be at greater risk of pregnancy-related weight gains. Overweight women are at greater risk of weight gain generally, but there is little unequivocal evidence to suggest that they are at any increased risk of maternal obesity, when compared with women of lower BMI.

How accurate are antenatal weight measurements? A survey of hospital and community clinics in a South Thames Region NHS Trust

The accuracy of antenatal weight data recorded in obstetric notes was investigated in the 45 hospital and community antenatal clinics within a South Thames Region NHS Trust. In order to assess the reliability and validity of all 60 clinic scales triplicate measurements of body weight for low- and high-weight subjects were recorded on each clinical scale and on a calibrated standard scale. The quality of weighing practice during antenatal care was investigated by means of semi-structured interviews conducted with all 33 midwives who currently provide antenatal care within the Trust. Beam balances had the highest reliability and validity, whereas scales with spring mechanisms were the least accurate. Only 40% of the clinics surveyed had access to beam balances, yet most of the maternal weight measurements recorded during antenatal care are likely to be out by no more than 1-1.5% of body weight. Weighing practice was generally inconsistent, and serial measurements of maternal body weight collected during pregnancy are probably too imprecise to provide a sensitive screen for conditions associated with unusual weight gain and too inaccurate to assess compliance with guidelines for weight gain.

Practical approaches for estimating prepregnant body weight

Measurements of prepregnant body weight have important research and clinical applications. In practice, however, they are not always recorded; even when they are, this information is not always readily available. For this reason, researchers and clinicians have to rely on retrospective estimates of prepregnant weight, which can be estimated using: 1) maternal self-reports, 2) retrospective extrapolation, or 3) standardized estimates that correct for weight gained during early pregnancy. The aim of the present study was to examine the relative merits of these three approaches. Maternal self-reports tend to be unreliable and biased, being influenced by a variety of sociodemographic characteristics that generally underestimate true prepregnant body weight. Estimates of prepregnant weight based on retrospective extrapolation are vulnerable to measurement error, transient fluctuations in body weight, and incorrectly assume that the rate of weight gain is constant throughout pregnancy. Standardized estimates that correct for weight gained during early pregnancy incorrectly presume that there is little interindividual variation in gestational weight gain and that weight gain is similar for each woman in consecutive pregnancies. Because none of these techniques can provide a precise measure of prepregnant weight, researchers have little alternative but to recruit and weigh women before they become pregnant, although measurements of body weight recorded during the first trimester of pregnancy may provide a reasonable indication of prepregnant weight. For clinicians, self-reports of prepregnant weight or measurements recorded early in pregnancy are probably sufficiently accurate for practical purposes whenever recent, accurate measurements of prepregnant weight are unavailable.

Adolescents' misperceptions of the dangerousness of acetaminophen in overdose

Clinical observations suggest that adolescents commonly and naively use acetaminophen in suicide attempts even when they do not wish to die. It is estimated that 18,500-mg acetaminophen tablets can lead to hepatotoxicity, while death is usually associated with ingestion of 50 or more tablets. A sample comprising 569 adolescent students completed an author-designed survey assessing teenagers' knowledge of acetaminophen's therapeutic and harmful effects. The findings support our original data that adolescents have ready access to acetaminophen and use it in suicide attempts, but underestimate its potential for toxicity. Forty-two percent of this sample underestimated the dose to cause harm, believing it would require 20 or more tablets, and 50% underestimated the dose to cause death, stating 100 or more pills would be necessary. Adolescents appear to seriously underestimate the dangerousness of acetaminophen in overdose, and lack knowledge regarding side effects of overdose.

Is there an independent association between parity and maternal weight gain?

The independent associations between parity and maternal body mass index (BMI), and between parity and maternal weight gain, were investigated using a combination of cross-sectional and longitudinal analyses based on a retrospective, repeat-pregnancy study that examined the change in maternal body weight from the beginning of one pregnancy to the beginning of the next. A group of 523 multiparous women who had been weighed regularly during pregnancy, and none of whom had fallen pregnant less than 12 months after the birth of their previous child, were examined. Sociodemographic, behavioural, medical, obstetric and perinatal data, together with antenatal measurements of maternal body weight and height, were abstracted from each mother's obstetric notes. Parity was found to be independently associated with maternal BMI (p < 0.001), gestational weight gain (p < 0.001) and interpregnancy weight gain (p = 0.032). Women of different parities were found to be at differential risk of long-term weight gain for two reasons. First, primiparous women are at risk of long-term weight gain because they gain the most weight during pregnancy, and high gestational weight gain is in itself a risk factor for long-term weight gain. Second, women of higher parity (4+) are at risk of long-term weight gain because they gain more weight in association with pregnancy, irrespective of the amount of weight they gain during their pregnancies. For women of parity 3 or less, the association between maternal body weight and parity appears to be the result of cumulative weight gained during successive pregnancies. For women of greater parity, the association between maternal body weight and parity is partly the result of cumulative excess gestational weight gained during successive pregnancies, and partly the result of gaining more weight from the beginning of one pregnancy to the next at later pregnancies.

Characterization of adhesion molecule expression in the pathogenesis of homologous collagen-induced arthritis in the DA rat

We have investigated the inflammatory cell infiltrates and adhesion molecule expression in the synovial fluid (SF) and synovial membranes (SM) of rats with homologous collagen-induced arthritis. Immunohistochemical staining revealed that the majority of the cells in the SF were granulocytes, expressing CD11b and CD11c. In SM, the majority of the cells were monocytes/macrophages. CD49d and CD49f were expressed mainly in the erosion zone in SM, and ICAM-1 was expressed in the lining layer, in the capillaries, and in the erosion zone. In SF 7% of the cells were ICAM-1 positive. CD2 was more abundant in SM than in SF. These findings might explain the difference in granulocyte counts between SF and SM. CD49d and CD49f expression might retain lymphocytes and monocytes in SM, while granulocytes not expressing CD49d and CD49f are not retained.

The impact of pregnancy on the long-term weight gain of primiparous women in England

OBJECTIVES

To investigate the impact of pregnancy on long-term weight gain of primiparous mothers in England, and to identify potential risk factors for maternal obesity.

DESIGN

A retrospective, repeat-pregnancy study which examined the change in maternal body weight from the beginning of the first successful pregnancy to the beginning of the second.

SUBJECTS

Two hundred and forty-three mothers, all of whom had been weighed during the first trimester of their first and second pregnancies, and none of whom had fallen pregnant less than 12 months after the birth of their first child.

MEASUREMENTS

Sociodemographic, behavioural, medical, obstetric and perinatal data, together with antenatal measurements of maternal body weight and height, were extracted from each mother's obstetric notes. A comprehensive survey of weighing scales used at all antenatal clinics was undertaken.

RESULTS

After accounting for the effect of ageing, there was no significant long-term increase in mean maternal body weight following the first pregnancy (95% Confidence Intervals: -0.82-0.28kg). While most mothers (70.8%) gained 1.0 kg or less, 24.7% gained more than 1.54 kg. Even after accounting for the maximum error in clinic scales, 14.8% of the mothers gained 1.54 kg or more in association with their first pregnancy. Mothers with higher BMIs at the beginning of their first pregnancy, who gained more weight during pregnancy, gave birth to heavier babies and had longer intervals between their pregnancies, gained significantly more weight from one pregnancy to the next.

CONCLUSIONS

Pregnancy has little impact on the mean weight gain of primiparous women from England, who have a low prevalence of obesity (BMI > or = 26.0, 25.5%). Nevertheless, pregnancy may be associated with a permanent increase in maternal body weight simply because it is a period of positive energy balance during which some women gain excessive weight. Other factors, such as prepregnant BMI, determine whether long-term weight gain actually occurs.

Methodological considerations in the design of an obstetric database abstracted from medical records

The quality of maternal information contained within contemporary obstetric notes was investigated by abstracting data from the medical records of multiparous women who were admitted to a major city hospital in the South Thames Region. Potential sources of error were identified by comparing information recorded in different sections of each obstetric notes and within the obstetric notes of consecutive pregnancies. The format of the obstetric notes largely determined which variables were recorded and, to some extent, the accuracy of information collected. However, the quality of the data ultimately depended upon whether each variable was self-reported or directly measured. Self-reported variables were subject to selective omission and subjective bias, while measured variables were susceptible to inaccurate equipment and poor measurement practice. By interviewing a sample of midwives currently involved in antenatal care at the Trust it was possible to confirm that extensive variation in measurement and recording procedures routinely occurred.

The reliability of hand-written and computerised records of birth data collected at Baragwanath hospital in Soweto

This study examined the reliability of hand written and computerised records of birth data collected during the Birth to Ten study at Baragwanath Hospital in Soweto. The reliability of record-keeping in hand-written obstetric and neonatal files was assessed by comparing duplicate records of six different variables abstracted from six different sections in these files. The reliability of computerised record keeping was assessed by comparing the original hand-written record of each variable with records contained in the hospital's computerised database. These data sets displayed similar levels of reliability which suggests that similar errors occurred when data were transcribed from one section of the files to the next, and from these files to the computerised database. In both sets of records reliability was highest for the categorical variable infant sex, and for those continuous variables (such as maternal age and gravidity) recorded with unambiguous units. Reliability was lower for continuous variables that could be recorded with different levels of precision (such as birth weight), those that were occasionally measured more than once, and those that could be measured using more than one measurement technique (such as gestational age). Reducing the number of times records are transcribed, categorising continuous variables, and standardising the techniques used for measuring and recording variables would improve the reliability of both hand-written and computerised data sets.

Adolescent psychopathy in relation to delinquent behaviors, conduct disorder, and personality disorders

The purpose of this study was to explore the relationship between psychopathy as measured by The Revised Psychopathy Checklist (PCL-R) and delinquent behaviors, conduct disorder, and personality disorders in psychiatrically hospitalized adolescents. Thirty adolescent inpatients were assessed for psychopathy, delinquent behaviors, DSM-III-R Axis I disorders, and personality disorders using the Revised Psychopathy Checklist (PCL-R), the Diagnostic Interview for Children and Adolescents (DICA-R), and the Structured Interview for DSM-III-R Personality Disorders (SIDP-R). Significant relationships were noted between elevated PCL-R psychopathy scores and delinquent behaviors, conduct disorder, and narcissistic personality disorder. The validity of the PCL-R as a measure of psychopathy in adolescence was supported. Longitudinal studies are needed to clarify the clinical application of the PCL-R to adolescent populations.

The binary complex of pig plasma gelsolin with Mg2+-G-actin in ATP and ADP

Pig plasma gelsolin combined with Mg-G-actin at less than 10(-8) M Ca2+ to yield a binary complex. Complexes formed from G-actin with bound ATP or ADP. They contained approx. 1 mol of non-exchangeable nucleotide per mol of actin. ATP hydrolysis was not coupled to binary complex formation, but ATP in the complex hydrolysed very slowly. The nucleotide in the binary complex behaved like one of the two nucleotide molecules in the ternary complex (two actin monomers to one gelsolin), but the actin-gelsolin interaction was weaker in the binary complex.

Preparation and characterization of pig plasma and platelet gelsolins

Pig plasma gelsolin has been prepared by a revised method involving poly(ethylene glycol) precipitation, chromatography on CM-cellulose and affinity chromatography on actin-Sepharose. Pig platelet gelsolin has been prepared by chromatography on DEAE-cellulose and actin-Sepharose. Partial chemical and proteolytic cleavage shows that the two proteins are closely related in their fragmentation patterns. The amino acid sequences are identical at the N-terminus of the platelet protein, but the plasma protein has an additional nine residues on the N-terminal side of the common sequence. Calcium binding studies show that the plasma protein has similar calcium binding properties to both macrophage and platelet gelsolins.

Covalent complexes formed between plasma gelsolin and actin with a zero-length cross-linking compound

Actin and plasma gelsolin were covalently cross-linked with the zero-length cross-linker 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. Two major intermolecularly linked products were identified on polyacrylamide gels. By use of 14C-labeled actin and 125I-labeled gelsolin, these were shown to be the 1:1 and 2:1 complexes of actin with gelsolin, respectively. The higher molecular weight complex predominated under all conditions tested including the presence and absence of Ca2+. In titration experiments in which actin at different concentrations was reacted with a fixed concentration of gelsolin, end points were obtained for the formation of both cross-linked species at about two actins per gelsolin, implying that a 2:1 noncovalent complex is cross-linked. In 0.1 mM Ca2+, the extent of cross-linking was independent of protein concentration down to 50 nM gelsolin. At low Ca2+ concentrations (less than 10(-8)M), the extent of cross-linking was very much reduced at micromolar gelsolin and fell to zero at about 100 nM gelsolin. The binding of actin to gelsolin to give a cross-linkable complex is therefore very strong at 0.1 mM Ca2+ but much weaker at low Ca2+ concentrations.

Lack of nucleotide cleavage on the binding of G-actin-ATP to plasma gelsolin

G-Actin-ATP bound to plasma gelsolin to form a 2:1 complex. The complex contained approximately equivalent amounts of nucleotide and actin. More than 84% of this nucleotide was ATP. Half of the bound nucleotide was displaced by cold chase and the remainder did not exchange, implying that the two actins in the complex are not equivalent.

Plasma gelsolin caps and severs actin filaments

Plasma gelsolin caps actin filaments at their 'barbed' ends and severs them along their length. Capping has been demonstrated both by direct visualization using gold-labeled gelsolin and by inhibition of actin polymerization onto the barbed ends of fragments of the acrosomal process of Limulus sperm. Severing activity is demonstrated by the fact that actin filaments nucleated off acrosomal fragments are shortened or removed within a few seconds by added plasma gelsolin without any obvious disruption of the actin bundles in the acrosomal processes themselves.

Plasma actin depolymerizing factor has both calcium-dependent and calcium-independent effects on actin

The effects of pig plasma actin depolymerizing factor (ADF) on both G-actin polymerization and F-actin fragmentation have been examined by using rabbit skeletal muscle actin labeled with N-(1-pyrenyl)iodoacetamide, a sensitive fluorescent probe for monomer to filament interconversion. Fluorescence data have been compared with results obtained by viscometry and by difference absorption measurements at 232 nm. Plasma ADF nucleates actin filament assembly in a Ca2+-dependent manner; actin polymerization rates are enhanced at greater than 10(-6) M Ca2+. The calcium concentration dependence of this effect, showing a shift in ADF nucleating capacity between 10(-6) and 10(-7) M Ca2+, is that expected for an intracellular regulatory effect, but in plasma, the protein would always be saturated with Ca2+. Although the rate of polymerization is markedly enhanced in the presence of calcium ions, the extent of polymerization (as determined by the amplitude of the fluorescence change or the specific viscosity) is reduced in the presence of ADF and shows little or no Ca2+ dependence. The critical concentration of actin monomers is increased in the presence of ADF whether calcium is present or not. When ADF is added to F-actin, there is an immediate fall in fluorescence. This conversion of filaments to monomers by ADF (as defined by the fluorescence changes) is unaffected by calcium concentration. Electron micrographs of F-actin treated with ADF show that the filaments are indeed shortened at both high and low calcium concentrations. Taken together, these observations are interpreted in terms of a model in which ADF has both Ca2+-sensitive and Ca2+-insensitive binding sites for actin.