Probiotic supplementation and risk of necrotizing enterocolitis and mortality among extremely preterm infants-the Probiotics in Extreme Prematurity in Scandinavia (PEPS) trial: study protocol for a multicenter, double-blinded, placebo-controlled, and registry-based randomized controlled trial

BACKGROUND

Extremely preterm infants, defined as those born before 28 weeks' gestational age, are a very vulnerable patient group at high risk for adverse outcomes, such as necrotizing enterocolitis and death. Necrotizing enterocolitis is an inflammatory gastrointestinal disease with high incidence in this cohort and has severe implications on morbidity and mortality. Previous randomized controlled trials have shown reduced incidence of necrotizing enterocolitis among older preterm infants following probiotic supplementation. However, these trials were underpowered for extremely preterm infants, rendering evidence for probiotic supplementation in this population insufficient to date.

METHODS

The Probiotics in Extreme Prematurity in Scandinavia (PEPS) trial is a multicenter, double-blinded, placebo-controlled and registry-based randomized controlled trial conducted among extremely preterm infants (n = 1620) born at six tertiary neonatal units in Sweden and four units in Denmark. Enrolled infants will be allocated to receive either probiotic supplementation with ProPrems® (Bifidobacterium infantis, Bifidobacterium lactis, and Streptococcus thermophilus) diluted in 3 mL breastmilk or placebo (0.5 g maltodextrin powder) diluted in 3 mL breastmilk per day until gestational week 34. The primary composite outcome is incidence of necrotizing enterocolitis and/or mortality. Secondary outcomes include incidence of late-onset sepsis, length of hospitalization, use of antibiotics, feeding tolerance, growth, and body composition at age of full-term and 3 months corrected age after hospital discharge.

DISCUSSION

Current recommendations for probiotic supplementation in Sweden and Denmark do not include extremely preterm infants due to lack of evidence in this population. However, this young subgroup is notably the most at risk for experiencing adverse outcomes. This trial aims to investigate the effects of probiotic supplementation on necrotizing enterocolitis, death, and other relevant outcomes to provide sufficiently powered, high-quality evidence to inform probiotic supplementation guidelines in this population. The results could have implications for clinical practice both in Sweden and Denmark and worldwide.

TRIAL REGISTRATION

( Clinicaltrials.gov ): NCT05604846.

Social Services Post-discharge and Their Association With Readmission in a 2016 Swedish Geriatric Cohort

OBJECTIVES

To describe the social services received by a 2016 Swedish cohort after discharge from inpatient geriatric care and to analyze the association between level of social services post-discharge and 30-day readmission.

DESIGN

Observational, closed-cohort study.

SETTING AND PARTICIPANTS

All patients admitted to 1 of 3 regionally operated inpatient geriatric care settings in Region Stockholm, Sweden, in 2016 (n = 7453).

METHODS

Individual-level data from medical records and population registries were linked using unique personal identification numbers. Descriptive statistics were reported for 4 levels of municipal social services post-discharge: long-term care, 1 to 50 home help hours per month, >50 home help hours per month, and no home help. Multinomial logistic regression was performed to analyze the association between level of social services post-discharge and 3 outcomes within 30 days: readmission, death without readmission, or neither readmission nor death.

RESULTS

Results show that almost 11% of patients were discharged to long-term care and 54% received municipal home help services. Individuals with no municipal home help or with 1 to 50 hours per month were more likely to be readmitted within 30 days compared with those in long-term care. Living with more than 50 hours of help was not associated with an increased likelihood of 30-day readmission.

CONCLUSIONS AND IMPLICATIONS

Patients who received inpatient geriatric care are significant users of municipal social services post-discharge. Living in long-term care or with extensive home help appears to be a protective factor in preventing readmission compared with more limited or no home help services. Care transitions for this frail patient group require careful social care planning. Supporting individuals discharged with fewer social service hours may help reduce readmissions.

Osteoporosis in Europe: a compendium of country-specific reports

This report describes epidemiology, burden, and treatment of osteoporosis in each of the 27 countries of the European Union plus Switzerland and the UK (EU 27+2).

INTRODUCTION

The aim of this report was to characterize the burden of osteoporosis in each of the countries of the European Union plus Switzerland and the UK in 2019 and beyond.

METHODS

The data on fracture incidence and costs of fractures in the EU27+2 was taken from a concurrent publication in this journal (SCOPE 2021: a new scorecard for osteoporosis in Europe) and country-specific information extracted. The information extracted covered four domains: burden of osteoporosis and fractures; policy framework; service provision; and service uptake.

RESULTS

The clinical and economic burden of osteoporotic fractures in 2019 is given for each of the 27 countries of the EU plus Switzerland and the UK. Each domain was ranked and the country performance set against the scorecard for all nations studied. Data were also compared with the first SCOPE undertaken in 2010. Fifteen of the 16 score card metrics on healthcare provision were used in the two surveys. Scores had improved or markedly improved in 15 countries, remained constant in 8 countries and worsened in 3 countries. The average treatment gap increased from 55% in 2010 to 71% in 2019. Overall, 10.6 million women who were eligible for treatment were untreated in 2010. In 2019, this number had risen to 14.0 million.

CONCLUSIONS

In spite of the high cost of osteoporosis, a substantial treatment gap and projected increase of the economic burden driven by aging populations, the use of pharmacological prevention of osteoporosis has decreased in recent years, suggesting that a change in healthcare policy concerning the disease is warranted.

Health status and health care utilization after discharge from geriatric in-hospital stay - description of a register-based study

Background

This study is the first part of a register-based research program with the overall aim to increase the knowledge of the health status among geriatric patients and to identify risk factors for readmission in this population. The aim of this study was two-fold: 1) to evaluate the validity of the study cohorts in terms of health care utilization in relation to regional cohorts; 2) to describe the study cohorts in terms of health status and health care utilization after discharge.

Methods

The project consist of two cohorts with data from patient records of geriatric in-hospital stays, health care utilization data from Stockholm Regional Healthcare Data Warehouse 6 months after discharge, socioeconomic data from Statistics Sweden. The 2012 cohort include 6710 patients and the 2016 cohort, 8091 patients; 64% are women, mean age is 84 (SD 8).

Results

Mean days to first visit in primary care was 12 (23) and 10 (19) in the 2012 and 2016 cohort, respectively. Readmissions to hospital was 38% in 2012 and 39% in 2016. The validity of the study cohorts was evaluated by comparing them with regional cohorts. The study cohorts were comparable in most cases but there were some significant differences between the study cohorts and the regional cohorts, especially regarding amount and type of primary care.

Conclusion

The study cohorts seem valid in terms of health care utilization compared to the regional cohorts regarding hospital care, but less so regarding primary care. This will be considered in the analyses and when interpreting data in future studies based on these study cohorts. Future studies will explore factors associated with health status and re-admissions in a population with multi-morbidity and disability.

Health insurance utilisation after ischaemic stroke in Sweden: a retrospective cohort study in a system of universal healthcare and social insurance

BACKGROUND

Stroke is one of the largest single-condition sources of the global burden of non-communicable disease in terms of disability-adjusted life-years and monetary costs, directly as well as indirectly in terms of informal care and productivity loss. The objective was to assess the population afflicted with ischaemic stroke in working age in the context of universal healthcare and social insurance; to estimate the levels of absence from work, the indirect costs related to that and to assess the associated patient characteristics.

METHODS

This was a retrospective register-based study; all individuals registered with an ischaemic stroke during 2008-2011 in seven Swedish regions, covering the largest cities as well as more rural areas, were included. Individual-level data were used to compute net days of sick leave and disability pension, indirect costs due to productivity loss and to perform regression analysis on net absence from work to assess the associated factors. Costs related to productivity loss were estimated using the human capital approach.

RESULTS

Women had significantly fewer net days of sick leave and disability pension than men after multivariable adjustment, and high-income groups had higher levels of sick leave than low-income groups. There were no significant differences for participants regarding educational level, region of birth or civil status. Indirect monetary costs amounted to €17 400 per stroke case during the first year, totalling approximately €169 million in Sweden.

CONCLUSION

The individual's burden of stroke is heavy in terms of morbidity, and the related productivity loss for society is immense. Income-group differences point to a socioeconomic gradient in the utilisation of the Swedish social insurance.

Readmission within three months after inpatient geriatric care-Incidence, diagnosis and associated factors in a Swedish cohort

INTRODUCTION

Readmissions are very costly, in monetary terms but also for the individual patient's safety and health. Only by understanding the reasons and drivers of readmissions, it is possible to ensure quality of care and improve the situation. The aim of this study was to assess inpatient readmissions during the first three months after discharge from geriatric inpatient care regarding main diagnosis and frequency of readmission. Furthermore, the aim was to analyze association between readmission and patient characteristics including demography and socioeconomics, morbidity, physical function, risk screening and care process respectively.

METHODS

The study includes all individuals admitted for inpatient care at three geriatric departments operated by the Stockholm region during 2016. Readmission after discharge was studied within three different time intervals; readmission within 10 days after discharge, within 11-30 days and within 31-90 days, respectively. Main diagnosis at readmission was assessed.

RESULTS

One fourth of the individuals discharged from inpatient geriatric care was readmitted during the first three months after discharge. The most common main diagnoses for readmission were heart failure, chronic obstructive pulmonary disease and pneumonia. Statistically significant risk factors for readmission included age, sex, number of diagnoses at discharge, and to some extent polypharmacy and destination of discharge.

CONCLUSIONS

Several clinical risk factors relating to physical performance and vulnerability were associated with risk of readmission. Socioeconomic information did not add to the predictability. To enable reductions in readmission rates, proactive monitoring of frail individuals afflicted with chronic conditions is necessary, and an integrated perspective including all stakeholders involved is crucial.

SCOPE 2021: a new scorecard for osteoporosis in Europe

This scorecard summarises key indicators of the burden of osteoporosis and its management in the 27 member states of the European Union, as well as the UK and Switzerland. The resulting scorecard elements, assembled on a single sheet, provide a unique overview of osteoporosis in Europe.

INTRODUCTION

The scorecard for osteoporosis in Europe (SCOPE) is a project of the International Osteoporosis Foundation (IOF) that seeks to raise awareness of osteoporosis care in Europe. The aim of this project was to develop a scorecard and background documents to draw attention to gaps and inequalities in the provision of primary and secondary prevention of fractures due to osteoporosis.

METHODS

The SCOPE panel reviewed the information available on osteoporosis and the resulting fractures for each of the 27 countries of the European Union plus the UK and Switzerland (termed EU27+2). The information obtained covered four domains: background information (e.g. the burden of osteoporosis and fractures), policy framework, service provision and service uptake, e.g. the proportion of men and women at high risk that do not receive treatment (the treatment gap).

RESULTS

There was a marked difference in fracture risk among the EU27+2 countries. Of concern was the marked heterogeneity in the policy framework, service provision and service uptake for osteoporotic fracture that bore little relation to the fracture burden. For example, despite the wide availability of treatments to prevent fractures, in the majority of the EU27+2, only a minority of patients at high risk receive treatment even after their first fracture. The elements of each domain in each country were scored and coded using a traffic light system (red, orange, green) and used to synthesise a scorecard. The resulting scorecard elements, assembled on a single sheet, provide a unique overview of osteoporosis in Europe.

CONCLUSIONS

The scorecard enables healthcare professionals and policy makers to assess their country's general approach to the disease and provide indicators to inform the future provision of healthcare.

Comparison of individual and neighbourhood socioeconomic status in case mix adjustment of hospital performance in primary total hip replacement in Sweden: a register-based study

BACKGROUND

Case mix adjustment is a pre-requisite for valid measurement of healthcare performance and socioeconomic status (SES) is important to account for. Lack of information on individual-level SES has led to investigations into using a proxy for SES based on patient area of residence. The objective of this study was to use neighbourhood SES for case mix adjustment of performance indicators in total hip replacement (THR) in Sweden, and to compare with use of individual SES.

METHODS

Data from patient administrative systems and the Swedish Hip Arthroplasty Register were extracted for all patients undergoing THR in four Swedish regions. For each subject, individual data and neighbourhood data on country of birth, educational level, and income were provided by Statistics Sweden. Three variables were selected for analysis of performance; EQ-5D, hip pain and length of stay (LoS). In addition to socioeconomic information, several important clinical characteristics were used as case mix factors. Regression analysis was used to study each variable's impact on the three outcome variables and model fit was evaluated using mean squared error.

RESULTS

A total of 27,121 patients operated between 2010 and 2016 were included in the study. Both educational level and income were higher when based on neighbourhood information than individual information, while proportion born in Sweden was similar. Higher SES was generally found to be associated with better outcomes and lower LoS, albeit with certain differences between the different measures of SES. The predictive ability of the models was increased when adding information on SES to the clinical characteristics. The increase in predictive ability was higher for individual SES compared to neighbourhood SES. When analysing performance for the two providers with most diverging case mix in terms of SES, the inclusion of SES altered the relative performance using individual as well as neighbourhood SES.

CONCLUSIONS

Incorporating SES improves case mix adjustment marginally compared to using only clinical information. In this patient group, geographically derived SES was found to improve case mix adjustment compared to only clinical information but not to the same extent as actual individual-level SES.

Predicting clinical outcome and length of sick leave after surgery for lumbar spinal stenosis in Sweden: a multi-register evaluation

PURPOSE

Lumbar spinal stenosis (LSS) can be surgically treated, with variable outcome. Studies have linked socioeconomic factors to outcome, but no nation-wide studies have been performed. This register-based study, including all patients surgically treated for LSS during 2008-2012 in Sweden, aimed to determine predictive factors for the outcome of surgery.

METHODS

Clinical and socioeconomic factors with impact on outcome in LSS surgery were identified in several high-coverage registers, e.g., the national quality registry for spine surgery (Swespine, FU-rate 70-90%). Multivariate regression analyses were conducted to assess their effect on outcome. Two patient-reported outcome measures, Global Assessment of leg pain (GA) and the Oswestry Disability Index (ODI), as well as length of sick leave after surgery were analyzed.

RESULTS

Clinical and socioeconomic factors significantly affected health outcome (both GA and ODI). Some predictors of a good outcome (ODI) were: being born in the EU, reporting no back pain at baseline, a high disposable income and a high educational level. Some factors predicting a worse outcome were previous surgery, having had back pain more than 2 years, having comorbidities, being a smoker, being on social welfare and being unemployed.

CONCLUSIONS

The study highlights the relevance of adding socioeconomic factors to clinical factors for analysis of patient-reported outcomes, although the causal pathway of most predictors' impact is unknown. These findings should be further investigated in the perspective of treatment selection for individual LSS patients. The study also presents a foundation of case mix algorithms for predicting outcome of surgery for LSS. These slides can be retrieved under Electronic Supplementary Material.

The Association of Pre-stroke Psychosis and Post-stroke Levels of Health, Resource Utilization, and Care Process: A Register-Based Study

Background: While approximately one percent of the global population is formally diagnosed with psychosis or schizophrenia, the actual number is expected to be significantly higher. These patients often consume more healthcare resources and have poorer somatic health. In this study, we analyze potential differences in health, resources, and care process between stroke patients with and without a previous diagnosis of psychosis or schizophrenia.

Methods: Ischemic stroke patients from seven regions in Sweden were identified via ICD-10 codes (I63.0-9) in regional administrative systems and the Swedish Stroke Register, and approximately 70% of all ischemic stroke cases in Sweden during 2008–2011 were included (n = 46,350). Relevant patient-level data from national registries were linked to enable multivariate regression analysis, including data on socioeconomics, mortality, municipality services, and filled prescriptions. History of psychosis or schizophrenia was defined via ICD-10 codes F20-29 (n = 389).

Results: Patient-reported functional outcomes at 3 months and 1 year were significantly lower in the psychosis subgroup, and stroke recurrence was higher. Patients with pre-stroke psychosis did not receive the same levels of reperfusion treatment as the non-psychosis group. Time at the stroke unit was the same, as were first-year levels of somatic care, but dispensation of antihypertensives was less common.

Conclusion: Our findings emphasize the importance of taking mental comorbidity into account during stroke treatment as well as when evaluating indicators for health, resources, and the care process, since mental comorbidity such as psychosis or schizophrenia may have a significant impact the year preceding and the year succeeding the stroke event.

Sociodemographic determinants and health outcome variation in individuals with type 1 diabetes mellitus: A register-based study

BACKGROUND

Socioeconomic status, origin or demographic attributes shall not determine the quality of healthcare delivery, according to e.g. United Nations and European Union rules. Health equity has been defined as the absence of systematic disparities and unwarranted differences between groups defined by differences in social advantages. A study was performed to investigate whether this was applicable to type 1 diabetes mellitus (T1D) care in a setting with universal, tax-funded healthcare.

METHODS

This retrospective registry-study was based on patient-level data from individuals diagnosed with T1D during 2010-2011 (n = 16,367) in any of seven Swedish county councils (covering ~65% of the Swedish population). Health equity in T1D care was analysed through multivariate regression analyses on absolute HbA1c level at one-year follow-up, one-year change in estimated glomerular filtration rate (eGFR) and one-year change in cardiovascular risk score, using selected sociodemographic dimensions as case-mix factors.

RESULTS

Higher educational level was consistently associated with lower levels of HbA1c, and so was being married. Never married was associated with worse eGFR development, and lower educational level was associated with higher cardiovascular risk. Women had higher HbA1c levels than men, and glucose control was significantly worse in patients below the age of 25.

CONCLUSION

Patients' sociodemographic profile was strongly associated with absolute levels of risk factor control in T1D, but also with an increased annual deterioration in eGFR. Whether these systematic differences stem from patient-related problems or healthcare organisational shortcomings is a matter for further research. The results, though, highlight the need for intensified diabetes management education and secondary prevention directed towards T1D patients, taking sociodemographic characteristics into account.

Association between sociodemographic determinants and health outcomes in individuals with type 2 diabetes in Sweden

BACKGROUND

Concurrent multifactorial treatment is needed to reduce consequent risks of diabetes, yet most studies investigating the relationship between sociodemographic factors and health outcomes have focused on only one risk factor at a time. Swedish health care is mainly tax-funded, thus providing an environment that should facilitate equal health outcomes in patients, independent of background, socioeconomic status, or health profile. This study aimed at investigating the association between several sociodemographic factors and diabetes-related health outcomes represented by HbA_1c , systolic blood pressure, low-density lipoprotein cholesterol, predicted 5-year risk of cardiovascular disease, and statin use.

METHODS

This large retrospective registry study was based on patient-level data from individuals diagnosed with type 2 diabetes during 2010 to 2011 (n = 416,228) in any of 7 Swedish regions (~65% of the Swedish population). Health equity in diabetes care analysed through multivariate regression analyses on intermediary outcomes (HbA_1c , systolic blood pressure, and low-density lipoprotein), predicted 5-year risk of cardiovascular disease and process (i.e., statin use) after 1-year follow-up, adjusting for several sociodemographic factors.

RESULTS

We observed differences in intermediary risk measures, predicted 5-year risk of cardiovascular disease, and process dependent on place of birth, sex, age, education, and social setting, despite Sweden's articulated vision of equal health care.

CONCLUSIONS

Diabetes patients' health was associated with sociodemographic prerequisites. Furthermore, in addition to demographics (age and sex) and disease history, educational level, marital status, and region of birth are important factors to consider when benchmarking health outcomes, e.g., average HbA_1c level, and evaluating the level of health equity between organizational units or between different administrative regions.

Sex as predictor for achieved health outcomes and received care in ischemic stroke and intracerebral hemorrhage: a register-based study

BACKGROUND

Differences in stroke care and health outcomes between men and women are debated. The objective of this study was to explore the relationship between patients' sex and post-stroke health outcomes and received care in a Swedish setting.

METHODS

Patients with a registered diagnosis of acute intracerebral hemorrhage (ICH) or ischemic stroke (IS) within regional administrative systems (ICD-10 codes I61* or I63*) and the Swedish Stroke Register during 2010-2011 were included and followed for 1 year. Data linkage to multiple other data sources on individual level was performed. Adjustments were performed for age, socioeconomic factors, living arrangements, ADL dependency, and stroke severity in multivariate regression analyses of health outcomes and received care. Health outcomes (e.g., survival, functioning, satisfaction) and received care measures (regional and municipal resources and processes) were studied.

RESULTS

Study population: 13,775 women and 13,916 men. After case-mix adjustments for the above factors, we found women to have higher 1-year survival rates after both IS (OR_female = 1.17, p < 0.001) and ICH (OR_female = 1.65, p < 0.001). Initial inpatient stay at hospital was, however, shorter for women (β_{female, IS} = - 0.05, p < 0.001; β_{female, ICH} = - 0.08, p < 0.005). For IS, good function (mRS ≤ 2) was more common in men (OR_female = 0.86, p < 0.001) who also received more inpatient care during the first year (β_female = - 0.05, p < 0.001).

CONCLUSIONS

A lower proportion of women had good functioning, a difference that remained in IS after adjustments for age, socioeconomic factors, living arrangements, ADL dependency, and stroke severity. The amount of received hospital care was lower for women after adjustments. Whether shorter hospital stay results in lower function or is a consequence of lower function cannot be elucidated. One-year survival was higher in men when no adjustments were made but lower after adjustments. This likely reflects that women were older at time of stroke, had more severe strokes, and more disability pre-stroke-factors that make a direct comparison between the sexes intricate.

Hospital comparison of stroke care in Sweden: a register-based study

BACKGROUND AND PURPOSE

The objective of this study was to estimate the level of health outcomes and resource use at a hospital level during the first year after a stroke, and to identify any potential differences between hospitals after adjusting for patient characteristics (case mix).

METHOD

Data from several registries were linked on individual level: seven regional patient administrative systems, Swedish Stroke Register, Statistics Sweden, National Board of Health and Welfare and Swedish Social Insurance Agency. The study population consisted of 14 125 patients presenting with a stroke during 2010. Case-mix adjusted analysis of hospital differences was made on five aspects of health outcomes and resource use, 1 year post-stroke.

RESULTS

The results indicated that 26% of patients had died within a year of their stroke. Among those who survived, almost 5% had a recurrent stroke and 40% were left with a disability. On average, the patients had 22 inpatient days and 23 outpatient visits, and 13% had moved into special housing. There were significant variations between hospitals in levels of health outcomes achieved and resources used after adjusting for case mix.

CONCLUSION

Differences in health outcomes and resource use between hospitals were substantial and not entirely explained by differences in patient mix, indicating tendencies of unequal stroke care in Sweden. Healthcare organisation of regions and other structural features could potentially explain parts of the differences identified.

Relationship between functional disability and costs one and two years post stroke

BACKGROUND AND PURPOSE

Stroke affects mortality, functional ability, quality of life and incurs costs. The primary objective of this study was to estimate the costs of stroke care in Sweden by level of disability and stroke type (ischemic (IS) or hemorrhagic stroke (ICH)).

METHOD

Resource use during first and second year following a stroke was estimated based on a research database containing linked data from several registries. Costs were estimated for the acute and post-acute management of stroke, including direct (health care consumption and municipal services) and indirect (productivity losses) costs. Resources and costs were estimated per stroke type and functional disability categorised by Modified Rankin Scale (mRS).

RESULTS

The results indicated that the average costs per patient following a stroke were 350,000SEK/€37,000-480,000SEK/€50,000, dependent on stroke type and whether it was the first or second year post stroke. Large variations were identified between different subgroups of functional disability and stroke type, ranging from annual costs of 100,000SEK/€10,000-1,100,000SEK/€120,000 per patient, with higher costs for patients with ICH compared to IS and increasing costs with more severe functional disability.

CONCLUSION

Functional outcome is a major determinant on costs of stroke care. The stroke type associated with worse outcome (ICH) was also consistently associated to higher costs. Measures to improve function are not only important to individual patients and their family but may also decrease the societal burden of stroke.

A prospective randomized exploratory study comparing the efficacy of once-daily topical 0.5% 5-fluorouracil in combination with 10.0% salicylic acid (5-FU/SA) vs. cryosurgery for the treatment of hyperkeratotic actinic keratosis

BACKGROUND

Actinic keratoses (AKs) are clinically significant and require therapy. Efficacy of low-dose (0.5%) 5-fluorouracil with 10% salicylic acid (5-FU/SA) has been shown in randomized comparative trials of hyperkeratotic lesions of various grades.

OBJECTIVES

To evaluate the efficacy, tolerability and safety of low-dose 5-FU/SA topical solution vs. cryosurgery in patients with moderate/severe (grade II/III) hyperkeratotic AKs (NCT01358851).

METHODS

In an exploratory, open, randomized study, patients with histologically confirmed moderate/severe hyperkeratotic AKs on the face/forehead or bald scalp received 6 weeks of once-daily topical 0.5% 5-FU/SA, or up to two cryosurgery treatments (3 weeks apart). Histological outcomes were determined from punch biopsies. Clinical, cosmetic and tolerability outcomes were also assessed.

RESULTS

Sixty-six patients received treatment (33 per arm). The baseline total number of lesions was 266 (8.1/patient) in the 0.5% 5-FU/SA and 263 (8.0/patient) in the cryosurgery group. Most (74.5%) lesions were grade II (grade III, 25.5%). Mean change in lesion count from baseline to Day 98 was -5.2 and -5.7 lesions per patient for 0.5% 5-FU/SA and cryotherapy groups respectively. Histological AK clearance rates on Day 98 were 62.1% and 41.9% respectively. At 6-month posttreatment follow-up, recurrence of cleared lesions (no clinically visible lesions in treatment area) occurred in 39.4% of 0.5% 5-FU/SA and 84.8% of cryosurgery patients. Drug-related adverse events (AEs), including local skin reactions considered 'severe' by the investigator, were reported in 24.2% of 0.5% 5-FU/SA and 6.1% of cryosurgery patients. All drug-related AEs were skin reactions.

CONCLUSIONS

Although the study was not powered to explore statistical differences in clinical efficacy between treatments, a short (6-week) schedule of topical treatment with 0.5% 5-FU/SA achieved greater histological clearance and lower recurrence of grade II/III hyperkeratotic AKs than cryosurgery. AE incidence across both treatment groups was relatively low and AEs were generally mild or moderate. Clinical trials.gov identifier: NCT01358851.

Bioavailability, antipsoriatic efficacy and tolerability of a new light cream with mometasone furoate 0.1%

Mometasone furoate, a potent glucocorticoid (class III) with a favorable benefit/risk ratio, has emerged as a standard medication for the treatment of inflammatory skin disorders. The purpose of the investigation presented here was to determine the noninferiority of a topical mometasone formulation, a light cream (O/W 60/40 emulsion) with mometasone furoate 0.1% (water content of 33%) versus marketed comparators. Using the vasoconstrictor assay, a strong blanching effect of the new cream (called Mometasone cream) comparable to that of a mometasone comparator, a fatty cream with mometasone furoate 0.1%, could be demonstrated. Thus, the topical bioavailability of the active ingredient mometasone furoate (0.1%) was regarded to be similar for Mometasone cream and the mometasone comparator. Using the psoriasis plaque test, a strong antipsoriatic effect comparable to that of the mometasone comparator was found for Mometasone cream after 12 days of occlusive treatment. A nearly identical reduction in the mean infiltrate thickness and similar mean AUC values were noted with both formulations confirmed by clinical assessment data. The noninferiority of Mometasone cream to its active comparator with respect to the AUC of change to baseline in infiltrate thickness was demonstrated. Both medications were well tolerated. Overall, Mometasone cream and the mometasone comparator showed similar efficacy and tolerability. Mometasone cream, in addition to its high potency and good tolerability, provides the properties of a light cream, which might make this new medication particularly suitable for application on acutely inflamed and sensitive skin.

Low-dose 5-fluorouracil in combination with salicylic acid as a new lesion-directed option to treat topically actinic keratoses: histological and clinical study results

BACKGROUND

Actinic keratoses (AKs) arise after chronic sun exposure. Because long-term ultraviolet (UV) damage may induce proliferation of atypical keratinocytes, treatment of AKs is recommended.

OBJECTIVES

To compare 5-fluorouracil 0·5%/salicylic acid 10·0% [low-dose 5-FU/SA (Actikerall®)] with diclofenac 3% in hyaluronic acid (diclofenac HA) and vehicle for the treatment of AKs.

METHODS

This was a randomized, placebo-controlled, double-blind, parallel-group, multicentre trial. Patients received topical low-dose 5-FU/SA once daily, its vehicle or diclofenac HA twice daily for a maximum of 12 weeks. The final evaluation was at week 20. The primary objectives were to demonstrate the histological clearance rate of one predefined lesion. The secondary objectives were the improvement of treated lesions, tolerability and safety.

RESULTS

There were 470 patients with 4-10 AK lesions each (grade I or II) on the face/forehead or bald scalp included in the study. Low-dose 5-FU/SA was superior to diclofenac HA (P < 0·01) and vehicle (P < 0·0001) for histological clearance of one representative lesion 8 weeks post-treatment. In 72·0%, 59·1% and 44·8% of patients in the low-dose 5-FU/SA, diclofenac HA and vehicle groups, respectively, the week-20 biopsy revealed no AKs. Significantly more lesions were cleared with low-dose 5-FU/SA (74·5%) compared with diclofenac HA (54·6%; P < 0·001) or vehicle (35·5%; P< 0·001). Low-dose 5-FU/SA was superior in terms of complete clinical clearance: 55·4%, vs. diclofenac HA (32·0%, P < 0·001) and vehicle (15·1%P < 0·001). Application-site disorders (mainly burning and inflammation) were more frequent with low-dose 5-FU/SA but mainly of mild to moderate intensity.

CONCLUSIONS

Topical low-dose 5-FU/SA demonstrated higher histological and clinical clearance rates vs. diclofenac HA or vehicle. Low-dose 5-FU/SA is an effective lesion-directed treatment for AKs.

QUANTIFICATION OF CHONDROCYTE MORPHOLOGY BY CONFOCAL ARTHROSCOPY

The purpose of this study was to determine the effectiveness of a novel Laser Scanning Confocal Arthroscope (LSCA) for the morphological quantification of articular cartilage chondrocytes.

Healthy and debrided regions of the knee articular cartilage of six (6) New Zealand White rabbits were imaged during open follow-up surgery. Quantitative morphological analysis of chondrocyte cell populations was performed and compared to known parameters. Optical histology images were compared to conventional histology of similar sites.

Optical histology revealed viable cells in normal hyaline cartilage tissue and enabled the visualization of fibro-cartilage in defect tissue. Morphological analysis was able to characterize the in vivo two-dimensional equivalent-area-diameter of chondrocytes. Significant differences (P<0.05) were seen between the morphology of chondrocytes observed in optical and conventional histology.

This study concludes that the LSCA is capable of illustrating the surface and sub-surface appearance of healthy and defect articular cartilage, thereby providing a non-destructive method for assessing cartilage condition in vivo. In this role the LSCA may find application in the investigation of cartilage pathologies or repair techniques.

Deletion of tolA in Salmonella Typhimurium generates an attenuated strain with vaccine potential

The Gram-negative Tol-Pal system of envelope proteins plays a key role in maintaining outer membrane integrity and contributes to the virulence of several pathogens. We have investigated the role of one of these proteins, TolA, in the biology of Salmonella enterica serovar Typhimurium. Deletion of tolA rendered strain SL1344 more susceptible to killing by bile and human serum. In addition the mutant had impaired membrane integrity and displayed alterations in LPS production. The tolA mutant was highly attenuated in mouse infections via the oral and intravenous routes. Importantly, each phenotype displayed by the mutant was complemented by provision of tolA in trans. The tolA gene therefore contributes to virulence, membrane integrity, LPS production and bile and serum resistance in S. enterica serovar Typhimurium SL1344. Finally, immunization with the tolA mutant provided significant protection against subsequent challenge with wild-type SL1344. The Tol-Pal system is therefore a potential target in the development of novel attenuated live vaccines against Salmonella and other Gram-negative pathogens.

An ex-vivo oral mucosa infection model for the evaluation of the topical activity of antifungal agents

Although Nystatin has been used since 1950s as a non-absorbable antifungal agent, there is still no reliable in-vivo data available stating a dose-effect relationship of Nystatin-suspension in the treatment of oropharyngeal infection with Candida albicans. Here, we studied the efficacy of a commercially available topical Nystatin suspension in a new ex-vivo model of candidiasis using porcine oral mucosa. After 48 and 96 h of C. albicans infection, 230 IU Nystatin (standard dosage), 100 IU and 20 IU proved to be equally efficacious. Multiple applications of Nystatin were not superior compared with single application. In dosages of 10 and 0.1 IU the activity of Nystatin suspension against C. albicans was no longer confirmed. In an agar diffusion model, the minimal biocidal concentration of Nystatin proved to be 0.25 IU. Our results suggest that the proposed porcine ex-vivo model is much closer to the in-vivo situation compared with other established in-vitro models of the treatment of muco-cutaneous candidiasis and may provide a substitute for animal models in the investigation of antifungal agents. Additionally, it seems to be a valuable tool for further investigations of the pathogenesis of C. albicans infections.

Matrix-induced autologous chondrocyte implantation in sheep: objective assessments including confocal arthroscopy

The assessment of cartilage repair has largely been limited to macroscopic observation, magnetic resonance imaging (MRI), or destructive biopsy. The aims of this study were to establish an ovine model of articular cartilage injury repair and to examine the efficacy of nondestructive techniques for assessing cartilage regeneration by matrix-induced autologous chondrocyte implantation (MACI). The development of nondestructive assessment techniques facilitates the monitoring of repair treatments in both experimental animal models and human clinical subjects. Defects (Ø 6 mm) were created on the trochlea and medial femoral condyle of 21 sheep randomized into untreated controls or one of two treatment arms: MACI or collagen-only membrane. Each group was divided into 8-, 10-, and 12-week time points. Repair outcomes were examined using laser scanning confocal arthroscopy (LSCA), MRI, histology, macroscopic ICRS grading, and biomechanical compression analysis. Interobserver analysis of the randomized blinded scoring of LSCA images validated our scoring protocol. Pearson correlation analysis demonstrated the correlation between LSCA, MRI, and ICRS grading. Testing of overall treatment effect independent of time point revealed significant differences between MACI and control groups for all sites and assessment modalities (Asym Sig < 0.05), except condyle histology. Biomechanical analysis suggests that while MACI tissue may resemble native tissue histologically in the early stages of remodeling, the biomechanical properties remain inferior at least in the short term. This study demonstrates the potential of a multisite sheep model of articular cartilage defect repair and its assessment via nondestructive methods.

Laser scanning confocal arthroscopy of a fresh cadaveric knee joint

OBJECTIVE

Osteoarthritis (OA) inflicts an enormous burden upon sufferers and healthcare systems worldwide. Continuing efforts to elucidate the aetiology of OA have indicated the need for non-destructive methods of in vivo microstructural assessment of articular cartilage (AC). In this study, we describe the first use of a recently developed laser scanning confocal arthroscope (LSCA) to image the cartilage of a fresh frozen cadaveric knee from a patient with OA.

DESIGN

Using an adaptation of the International Cartilage Repair Society (ICRS) joint mapping protocol, the joint was divided into three discrete regions (femoral condyle, patella and tibial plateau) for grading according to the ICRS (Outerbridge) system. The LSCA was used to generate images from each area within the three regions. Following imaging, the joint was sectioned and histology was performed on the corresponding sites with histological grading (modified-Mankin).

RESULTS

Quantitative results of ICRS, LSCA and histological OA assessment were compared using intraclass correlation (ICC) and Pearson correlation analysis. The LSCA enabled visualisation of chondrocyte morphology and cell density, with classical OA changes such as chondrocyte clustering, surface fibrillation and fissure formation evident. Obvious qualitative similarities between LSCA images and histology were observed, with fair to moderate agreement (P<0.05) demonstrated between modalities.

CONCLUSIONS

In this study, we have shown the viability of the LSCA for non-destructive imaging of the microstructure of OA knee cartilage. LSCA technology is potentially a valuable research and clinical tool for the non-destructive assessment of AC microstructure in early to late OA.

Evidence of circulating donor genetic material in bone allotransplantation

Musculoskeletal allotransplantion is the most common form of human tissue transplantation. Unlike solid organ transplants, bone allotransplants undergo rigorous processing and are considered non-viable tissue. In this study, we propose that donor genetic material may exist in circulation after bone allotransplantation. Fifty-one female patients who received bone allotransplants from male donors were assessed. Blood plasma samples were analyzed using real-time quantitative polymerase chain reaction (PCR) with dual labeled fluorogenic probes for the presence of the SRY gene on the Y chromosome. Of the total 51 patients, the SRY sequence was detected in 6 patients. Five were positive at day 1 postoperatively and negative thereafter, with the remaining patient positive at 3 months post-transplantation. Our results document, for the first time, the presence of donor DNA in the circulation of recipients after bone allotransplantation. Our findings suggest a potential new investigative tool to assess the postoperative status of bone allotransplants.

Autologous chondrocyte implantation with collagen bioscaffold for the treatment of osteochondral defects in rabbits

Osteochondral injury is therapeutically irreversible within current treatment parameters. Autologous chondrocyte implantation (ACI) promises to regenerate hyaline articular cartilage, but conventional ACI is plagued by complications determined by periosteal grafting. Here we propose the utilization of collagen membrane in ACI as an effective bioscaffold for the regeneration of osteochondral lesions. Using a rabbit model of osteochondral injury, we have inoculated autologous chondrocytes onto a type I/III collagen scaffold [so-called matrix-induced ACI (MACI)] and implanted into 3-mm osteochondral knee defects. All untreated defect histology showed inferior fibrocartilage and/or fibrous tissue repair. In our time-course study, ACI with type I/III collagen membrane regenerated cartilage with healthy osteochondral architecture in osteochondral defects at 6 weeks. At 12 weeks, articular cartilage regeneration was maintained, with reduced thickness and proteoglycan compared with the adjacent cartilage. Both 6-week (p < 0.01) and 12-week (p < 0.05) ACI with collagen membrane showed significant improvement as compared with untreated controls. To further examine the efficacy of cartilage regeneration by ACI, we conducted a dose-response study, using chondrocytes at various cell densities between 10(4) and 10(6) cells/cm(2). The results showed that cell density had no effect on outcome histology, but all cell densities were significantly better than untreated controls (p < 0.01) and cell-free collagen membrane treatment (p < 0.05). In short, our data suggest that autologous chondrocyte-seeded type I/III collagen membrane is an effective method for the treatment of focal osteochondral knee injury in rabbits.

Porcine small intestine submucosa (SIS) is not an acellular collagenous matrix and contains porcine DNA: possible implications in human implantation

Porcine small intestinal submucosa (SIS) has been recommended as a cell-free, biocompatible biomaterial for the repair of rotator cuff tendon tear. However, we have observed noninfectious edema and severe pain in patients who have undergone SIS implantation for tendon repair. The aim of this study was to conduct an independent assessment of the safety and efficacy of Restore SIS membrane. The Restore orthobiologic implant was examined by histology and the nested PCR technique using porcine immunoreceptor DAP12 gene to examine if SIS membrane contained porcine cells or DNA, respectively. The material was also implanted into mice and rabbits for the evaluation of biological reaction and inflammatory response. Restore SIS was found to contain multiple layers of porcine cells. Chloroacetate esterase staining showed that some of these cells were mast cells. Nested PCR of the DAP12 gene demonstrated that Restore SIS contained porcine DNA material. Subcutaneous implantation of Restore SIS membrane in mice, and in rabbits for rotator cuff tendon repair, showed that the membrane caused an inflammatory reaction characterized by massive lymphocyte infiltration. In conclusion, Restore SIS is not an acellular collagenous matrix, and contains porcine DNA. Our results contradict the current view that Restore SIS is a cell-free biomaterial, and that no inflammatory response is elicited by its implantation. We suggest that further studies should be conducted to evaluate the clinical safety and efficacy of SIS implant biomaterials.

An aberrant form of CD59 derived from HeLa cells

We isolated a CD59 cDNA from a HeLa cell library which encoded a mutated form of CD59, having a single base substitution (G to T) that changed Arg55 to Met. Since this mutation occurred in the vicinity of the putative active site of CD59, we expressed the aberrant form of the protein in Chinese hamster ovary cells in order to test for effects upon function. We found that the mutation did not influence complement inhibitory activity of CD59. However, the epitopes recognised by the function-blocking CD59 monoclonal antibodies BRIC229 and YTH 53.1 were significantly affected. The G to T substitution caused loss of an Mnl I restriction site which permitted PCR-RFLP analysis. All of 52 human subjects studied, and our in-house HeLa cells, were homozygous for the normal CD59 sequence, indicating that the altered sequence was not due to normal variation in the general population. Therefore this mutation probably arose spontaneously in the HeLa cell line used to generate the commercially obtained cDNA library.

Interaction between host complement and mosquito-midgut-stage Plasmodium berghei

After ingestion by mosquitoes, gametocytes of malaria parasites become activated and form extracellular gametes that are no longer protected by the red blood cell membrane against immune effectors of host blood. We have studied the action of complement on Plasmodium developmental stages in the mosquito blood meal using the rodent malaria parasite Plasmodium berghei and rat complement as a model. We have shown that in the mosquito midgut, rat complement components necessary to initiate the alternative pathway (factor B, factor D, and C3) as well as C5 are present for several hours following ingestion of P. berghei-infected rat blood. In culture, 30 to 50% of mosquito midgut stages of P. berghei survived complement exposure during the first 3 h of development. Subsequently, parasites became increasingly sensitive to complement lysis. To investigate the mechanisms involved in their protection, we tested for C3 deposition on parasite surfaces and whether host CD59 (a potent inhibitor of the complement membrane attack complex present on red blood cells) was taken up by gametes while emerging from the host cell. Between 0.5 and 22 h, 90% of Pbs21-positive parasites were positive for C3. While rat red and white blood cells stained positive for CD59, Pbs21-positive parasites were negative for CD59. In addition, exposure of parasites to rat complement in the presence of anti-rat CD59 antibodies did not increase lysis. These data suggest that parasite or host molecules other than CD59 are responsible for the protection of malaria parasites against complement-mediated lysis. Ongoing research aims to identify these molecules.

Streptococcal inhibitor of complement (SIC) inhibits the membrane attack complex by preventing uptake of C567 onto cell membranes

Streptococcal inhibitor of complement (SIC) was first described in 1996 as a putative inhibitor of the membrane attack complex of complement (MAC). SIC is a 31 000 MW protein secreted in large quantities by the virulent Streptococcus pyogenes strains M1 and M57, and is encoded by a gene which is extremely variable. In order to study further the interactions of SIC with the MAC, we have made a recombinant form of SIC (rSIC) in Escherichia coli and purified native M1 SIC which was used to raise a polyclonal antibody. SIC prevented reactive lysis of guinea pig erythrocytes by the MAC at a stage prior to C5b67 complexes binding to cell membranes, presumably by blocking the transiently expressed membrane insertion site on C7. The ability of SIC and clusterin (another putative fluid phase complement inhibitor) to inhibit complement lysis was compared, and found to be equally efficient. In parallel, by enzyme-linked immunosorbent assay both SIC and rSIC bound strongly to C5b67 and C5b678 complexes and to a lesser extent C5b-9, but only weakly to individual complement components. The implications of these data for virulence of SIC-positive streptococci are discussed, in light of the fact that Gram-positive organisms are already protected against complement lysis by the presence of their peptidoglycan cell walls. We speculate that MAC inhibition may not be the sole function of SIC.

Antigen S1, encoded by the MIC1 gene, is characterized as an epitope of human CD59, enabling measurement of mutagen-induced intragenic deletions in the AL cell system

S1 cell membrane antigen is encoded by the MIC1 gene on human chromosome 11. This antigen has been widely used as a marker for studies in gene mapping or in analysis of mutagen-induced gene deletions/mutations, which utilized the human-hamster hybrid cell-line, AL-J1, carrying human chromosome 11. Evidence is presented here which identifies S1 as an epitope of CD59, a cell membrane complement inhibiting protein. E7.1 monoclonal antibody, specific for the S1 determinant, was found to react strongly with membrane CD59 in Western blotting, and to bind to purified, urinary form of CD59 in ELISAs. Cell membrane expression of S1 on various cell lines always correlated with that of CD59 when examined by immunofluorescent staining. In addition, E7.1 antibody inhibited the complement regulatory function of CD59. Identification of S1 protein as CD59 has increased the scope of the AL cell system by enabling analysis of intragenic mutations, and multiplex PCR analysis of mutated cells is described, showing variable loss of CD59 exons.

Construction of a consistent YAC contig for human chromosome region 3p14.1

Chromosomal deletions and translocations of human chromosome region 3p14 are observed in various human malignancies and suggest the existence of a tumor suppressor gene locus within this region. Tumors most frequently affected by these aberrations are small-cell lung cancer and renal-cell carcinoma. In continuation of our previously published YAC contig of chromosome region 3p14.2-p14.3, we report here on the construction of a YAC contig of at least 11 Mb that consisted of 171 YACs and covers the entire subregion 3p14.1. This contig includes the t(3;8) breakpoint of a hereditary renal-cell carcinoma localized in 3p14.2 and extends into human chromosome region 3p12-p13. It defines the order of 34 DNA probes in relation to reference markers D3S6 and D3S30 as well as the human protein tyrosine phosphatase-gamma gene. For 31 DNA probes we identified nonchimeric YACs by fluorescence in situ hybridization. The minimal tilling pathway consists of 16 yeast artificial chromosomes. As a prerequisite for identification of a putative tumor suppressor gene within this region, this contig renders human chromosome region 3p14.1 accessible to gene isolation.

Identification of MIC 11 antigen as an epitope of the CD59 molecule

The MIC 11 antigen is expressed on human cells and is characterized by reaction with a monoclonal antibody (mAb), 16.3A5. The gene controlling MIC 11 was recently mapped to the p13 region of chromosome 11 within 500 kb of the gene encoding CD59, a complement regulatory protein. The present report investigates the antigenic relationship between these cell-membrane determinants and sets out evidence that MIC 11 and CD59 are encoded by the same gene. Western blotting of human erythrocyte membrane proteins and purified membrane CD59 showed that 16.3A5 anti-MIC 11 antibody bound to a 19-24,000 MW band with the characteristic appearance of CD59 protein, and gave staining patterns identical to those obtained with the CD59 antibody, BRIC 229. The binding of 16.3A5 monoclonal IgG to purified urine-derived CD59 in enzyme-linked immunosorbent assay (ELISA) was inhibited by YTH 53.1 rat CD59 antibody, indicating that the MIC 11 epitope is the same as, or close to, that recognized by CD59 antibodies such as YTH 53.1, BRIC 229 and 2/24. Prior exposure of erythrocytes to 16.3A5 anti-MIC 11 also reduced the ability of the CD59 antibodies, BRIC 229 and YTH 53.1, to block the complement-inhibiting function of membrane CD59. Anti-MIC 11 antibody alone, however, had no inhibitory effect on CD59 function. This may be due to its relatively low binding affinity or to some slight difference in epitope specificity. Further studies using immunofluorescence showed that the MIC 11 epitope, like CD59, is absent from EBV-B cells lacking GPI-anchored proteins and from a B-cell line specifically deficient in CD59 protein. Overall, the results provide strong evidence that MIC 11 is a determinant on the CD59 molecule.

Characterization and chromosomal assignment of yeast artificial chromosomes containing human 3p13-p21-specific sequence tagged sites

Human chromosomal region 3p12-p23 is proposed to harbor at least three tumor suppressor genes involved in the development of lung cancer, renal cell carcinoma, and other neoplasias. In order to identify one of these genes we defined sequence tagged sites (STSs) specific for 3p13-p24.2 by analyzing a chromosome 3p14 microdissection library. STSs were used for isolating yeast artificial chromosome (YAC) clones from the Centre d'Etude du Polymorphisme Humain (CEPH) YAC libraries. Thirty-eight YACs were assembled into a contig approximately 2.5 Mb in size spanning the t(3;8) and t(3;6) translocation breakpoints associated with hereditary renal cell carcinoma and hematologic malignancies, respectively. Chromosomal localization and chimeric status of 126 YACs was analyzed by fluorescence in situ hybridization (FISH). The order of 17 YACs determined by double-color FISH was in agreement with the STS-based arrangement of the YAC-contig.

Glycosylation governs the binding of antipeptide antibodies to regions of hypervariable amino acid sequence within recombinant gp120 of human immunodeficiency virus type 1

Antibodies raised to an overlapping series of peptides following the amino acid sequence of the external envelope glycoprotein (gp 120) of human immunodeficiency virus type 1 (HIV-1) recognize eight regions in recombinant gp 120 molecules. If the recombinant molecules are glycosylated, three of these regions show a reduced capacity to bind antibody. Of the other five regions, two are strain-specific and carbohydrate restricts antibody binding to their N-terminal flanks, and three can be recognized by antibodies in recombinant gp 120 from an unrelated strain of HIV-1. Antibodies in sera from HIV-1-infected patients bind at high levels to peptides from five regions of gp 120. Of these regions, two coincide with those recognized by antibodies raised to peptides. Four of the five epitopes recognized by the rat antipeptide sera whose ability to bind antibody is influenced most by glycosylation, and three of the five regions which induce high levels of antibodies in patients' sera, contain putative glycosylation sites which are variable between strains of HIV-1. Such sites flank the putative neutralization and CD4-binding regions of gp 120. It is suggested that changes in the number and position of carbohydrate moieties following mutation can alternately mask and reveal epitopes. Masking an epitope can render a virus resistant to neutralization, whereas virus which binds antibody without being neutralized is able to gain entry to cells bearing antibody and complement receptors. Changes in the glycosylation pattern of gp 120 may therefore contribute to the control of HIV-1 spread within its host.

The immunodominance of epitopes within the transmembrane protein (gp41) of human immunodeficiency virus type 1 may be determined by the host's previous exposure to similar epitopes on unrelated antigens

Six major epitopes have been recognized within the transmembrane gp41 molecule of human immunodeficiency virus type 1 (HIV-1). The immunodominant epitope is also recognized by antibodies in sera from laboratory personnel and is similar to a linear sequence of amino acids in the genome protein of two rhinovirus serotypes. The hypothesis is presented that immunodominance is produced by multiple priming of the host, following repeated infections with viruses unrelated to HIV-1, which share similar epitopes.