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R Vranckx

Publications and source records attributed to R Vranckx.

97 records · Page 6Linked to original sources
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Hepatitis A virus antibodies in Belgium: relationship between prevalence and age.

Epidemiological data from various countries show that the frequency of Hepatitis A virus antibodies (anti-HAV) in different population groups is largely dependent on the geographical and age distribution of the population surveyed. As regards Europe anti-HAV antibodies are generally frequent in all groups in Southern Europe while in Northern Europe these antibodies are common in older people only. The prevalence data collected in 1979 and in 1989 show that the anti-HAV antibodies rate is a function of age, but the rates for all age groups were lower in 1989 compared to 1979. In 1979, at an age between 25 and 30, some 50% of the population was anti-HAV antibody positive. The same results were obtained in another Belgian study conducted in 1979. In 1989 50% positivity was only reached at an age between 35 and 40 years. The present study confirms that anti-HAV antibody prevalence decreases with higher socioeconomic status. The higher rate relative to age is associated with socioeconomic and hygienic living conditions at the time when most infections occur, i.e. before the age of 20. It can be concluded by comparing the 1979 and 1989 results that the number of adults susceptible to HAV infections has increased. This fact drew attention in view of the strongly altered travelling pattern of fairly large sections of the population.

Adult↗
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Hepatitis A virus infections in Belgian children.

In childhood HAV infection most often passes subclinically. In this study we evaluate the percentages of clinically and subclinically developing HAV infections and the age distribution of the prevalence of immunity to HAV. The study population (n = 1,008) included newborns, children and teenagers up to 20 years of age from the Brussels area. Sera were randomly collected at a general hospital. Subjects were stratified into six age groups. Among children and teenagers, the overall prevalence of anti-HAV (IgG) was 13.4%; this prevalence increased from 4.8% among children in the first group (1-2-year-olds) to 33.9% in the group of teenagers (16-20-year-olds). Among children and teenagers, 10% HAV infections on average is clinically recognized. For the different age groups, these figures are 3.5%, 18.7%, 12.3% and 5.5%, respectively. It can be concluded that, relative to the overall population of each age group, 0.3%, 1.8%, 1.6% and 0.3%, respectively, will have a clinically recognized HAV infection as members of that specific age group.

Adolescent↗
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The physicochemical and biological properties of alpha-fetoprotein depend of its ligand environment.

The majority of studies have concentrated on the endocrine and immunological roles of alpha-fetoprotein (AFP). These studies have been strongly orientated and sustained by research showing that rat and mouse AFPs competitively bind estrogen and non-esterified fatty acids. AFPs of other species, such as humans, are not estrogenophilic but all those studied to date bind NEFAs tightly. Endogenous ligands can greatly influence the conformation of the protein and consequently its biological activity. AFP may have three possible mechanisms of action: a) Murine AFP may be a modulatory element of estrogen expression which determines, under the control of NEFAs the concentration of the active free steroid. b) The protein could be transformed by bound ligands, so enhancing or inhibiting its binding to a target cell receptor, and consequently modifying its biological activity. AFP per se, can be the regulatory element. c) AFPs of all species can work as fatty acid binding proteins and modulate the availability of free NEFAs (not bound to protein). These free NEFAs can, in turn, act positively or negatively on various proteins involved in the pathways of the transfer of the steroid and peptide informations leading to cell multiplication or differentiation.

Animals↗
PubMedDate not supplied

The shift in prevalence of hepatitis A immunity in Flanders, Belgium.

The purpose of this study was to obtain data on the prevalence of hepatitis A in Flanders, Belgium, in order to analyse any change in the epidemiological pattern of hepatitis A virus (HAV) in the region, and to determine at which age pre-vaccination testing would be useful. To meet these goals, a sero-epidemiological survey was conducted: 4058 serum samples were collected from a random sample of the general population in 1993-94. The overall age-standardised prevalence was 51.3%. Among non-Belgians (N = 245), the age-standardised anti-HAV prevalence was 66.4%, significantly higher than the 49.6% anti-HAV prevalence found in Belgians (N = 3186). Among Belgians, seroprevalence increased with age: from 5.4% in the youngest age group (0-14 years) to over 80% in the two oldest age groups (55-64 years and > or = 65 years). Prevalence rates were as high as 31.7% in the 25-34 year old age category, and 60.8% in the 35-44 year old age category. The age-specific prevalence figures among Belgians and non-Belgians reflect two different epidemiological patterns: the epidemiological pattern of a low endemic region for Belgians and the epidemiological profile of an intermediate endemic region forn non-Belgians. The age-specific prevalence figures in Belgians were compared with the 1979 and 1989 anti-HAV prevalence figures in Belgian first-time blood donors. A clear epidemiological shift showing decreasing HAV prevalence in the youngest age groups was found. If we accept that pre-vaccination screening is useful at a 35% prevalence rate, all persons over 35 years of age should be screened before vaccination.

Adolescent↗