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M Koopmans

Publications and source records attributed to M Koopmans.

At least 19 recordsLinked to original sources
PubMed2002

Human caliciviruses in Europe.

Caliciviruses are single-stranded RNA viruses, which are divided into four genera based on their morphology and genomic structure. Viruses from two genera, the Norwalk like viruses and Sapporo like viruses, are a common cause of acute, nonbacterial gastroenteritis in humans. Although the first human calicivirus discovered nearly 30 years ago, much of the epidemiological and biological character of these viruses is only now beginning to unfold. Investigation has been difficult due to a number of factors, the viruses cannot be amplified by in vitro cell culture or animal models and electron microscopy (EM) is often not sensitive enough to detect the viruses in stool samples. Recent advances in molecular diagnostic techniques and the advent of a baculovirus expression system have highlighted the clinical and public health importance of calicivirus in all age groups, their ability to cause infection via a number of transmission routes as well as their considerable genetic diversity. These characteristics, in conjunction with the inability of humans to develop long-term immunity make HuCV an important public health issue in Europe and worldwide.

Animals↗
PubMed2001

Molecular epidemiology of human enteric caliciviruses in The Netherlands.

Caliciviruses are among the most common causes of gastroenteritis in people of all age groups. These antigenetically and genetically diverse viruses have been grouped into two genera within the family Caliciviridae, designated Norwalk-like viruses (NLV) and Sapporo-like viruses (SLV). To gain more insight in their epidemiology, we have developed a tentative genotyping scheme, which was used to differentiate the viruses detected in a set of epidemiological studies. NLVs and SLVs were detected by generic RT-PCR in stool specimens from 5.1% and 2.4% of cases with acute gastroenteritis for which a general practitioner was consulted, and in 16.5% and 6.3% of community cases of gastroenteritis. In addition, NLVs were associated with more than 80% of reported outbreaks of gastroenteritis from 1994-1999. Typically, several genotypes of NLV co-circulate in the community. Occasionally, however, several consecutive outbreaks were caused by essentially the same virus, although an epidemiological link had not previously been noted. This was most pronounced in 1995/1996, when a Lordsdale-like variant was detected that subsequently was found worldwide. This epidemic spread suggests differences in virulence or mode of transmission. In addition, we found that related NLVs are highly prevalent in calves in The Netherlands, raising questions about their potential for zoonotic transmission.

Animals↗
PubMed2000

Emerging group-A rotavirus and a nosocomial outbreak of diarrhoea.

A P[6]G9 group-A rotavirus caused a protracted hospital outbreak of neonatal diarrhoea in The Netherlands. The outbreak lasted 5 months with 52 cases and an average attack rate of 40%, 46 cases were in an incubator section for neonates under 1 month of age. Rotavirus P161G9 was detected by RT-PCR in stool samples from the 31 cases tested. Emergence of this genotype in Europe may have implications for neonates lacking protective maternal antibodies and for the development of rotavirus vaccines.

Cross Infection↗
PubMed2000

Isinglass/collagen: denaturation and functionality.

Isinglass is widely used commercially to clarify alcoholic beverages by aggregation of the yeast and other insoluble particles. It is derived from swim bladders of tropical fish by solubilisation in organic acids and consists predominantly of the protein collagen. The low content of intermolecular cross-links allows ready dissolution of swim bladder compared to bovine hide which is cross-linked by a high proportion of stable bonds and requires enzymic digestion to solubilise. Isinglass is no longer effective as a clarifying agent if thermally denatured hence the collagenous triple helical structure must be maintained. Thermal denaturation of isinglass occurs at 29 degrees C, compared to 40-41 degrees C for mammalian collagens, primarily due to the lower hydroxyproline content. The hydroxyproline is essential for the formation of H-bonded water-bridges through the hydroxyl group and the peptide chain thereby stabilising the triple helix. Based on the lower enthalpy determined by differential scanning calorimetry we have calculated that the thermally labile domain of the isinglass molecule was 41 residues compared to 66 for mammalian collagen. The fining efficiency was unaffected by pH, chelating agents, detergents and removal of surface proteins from yeast cells. Studies on the mechanism of action of isinglass have shown that higher molecular weight aggregates that increase the length of the collagen molecules (trimers, tetramers, etc.) increase efficiency and that their surface charge are important in the clarification process. By chemical modification, we have shown that blocking positively charged groups had no effect on the fining process, whilst negative charges are clearly essential and that increasing the negative charge by succinylation increases its efficacy. Solutions of bovine hide collagen were shown to be equally effective in refining beers and standard yeast preparations. The higher thermal denaturation temperature, ready availability and reproducibility of bovine collagen preparations gives it considerable advantages over isinglass.

Air Sacs↗
PubMed2000

Capsid protein diversity among Norwalk-like viruses.

We have determined the complete capsid gene sequence of 20 Norwalk-like viruses (NLVs) collected predominantly from outbreaks in the UK between 1989 and 1996. These comprised nine genogroup I and eleven genogroup II strains. Phylogenetic analysis of these and 15 published sequences suggest seven genomic sub-groups within genogroup I, including three previously described. In genogroup II, eight sub-groups were apparent, of which four were novel. Amino acid identities between strains of distinct genogroups ranged from 37 to 44% while varying between 61 and 100% for strains within a genogroup. Separate phylogenetic analyses of the N-terminus and central variable region of the capsid showed good correlation. Sequence divergence between strains was greatest within the central variable region, with amino acid sequence identities as low as 28% within a genogroup. These 15 genomic sub-groups provide a framework for further investigations of genetic and antigenic relationships within this calicivirus clade.

Amino Acid Sequence↗
PubMed2000

Molecular epidemiology of human enteric caliciviruses in The Netherlands.

In The Netherlands, illness due to Norwalk-like viruses (NLVs) of the family Caliciviridae is quite common. NLVs cause >80% of the outbreaks of gastroenteritis reported to municipal public health centers and at least 5% of the cases of gastroenteritis for which a general practitioner is consulted. In addition, up to 18% of community cases of gastroenteritis in the 1998/1999 winter season have been attributed to NLVs. Patterns of disease activity differ remarkably, with "normal years, when outbreaks occur that are caused by different types of NLV, and "epidemic years, when outbreaks appear to be caused by a single strain. This observation suggests selection of antigenic variants with increased virulence or altered modes of transmission. In addition, since caliciviruses related to the NLVs from humans have been detected in stool specimens from calves at 45% of the dairy farms in The Netherlands, the possibility of spillover of epidemic strains from an animal reservoir to humans should be considered.

Animals↗
PubMed2000

Cold weather seasonality of gastroenteritis associated with Norwalk-like viruses.

Norwalk-like viruses (NLVs) are the most common cause of acute nonbacterial gastroenteritis in adults, but little is known about their seasonality. The lack of specific diagnostic tools impeded study of these viruses in the past, and surveys using electron microscopy often grouped NLVs with other unrelated viruses. A search of the scientific literature found eight surveys of gastroenteritis, which were conducted for at least 1 year, that specifically identified NLVs. Unpublished data from laboratories of 4 NLV researchers were also used. These surveys, which were conducted in eight countries, reported sporadic cases and outbreaks of NLV-associated gastroenteritis among all age groups. The monthly occurrence of these cases and outbreaks was plotted, and while transmission occurred year-round in most surveys, a cold weather peak was demonstrated in 11 of the 12 studies. This key epidemiologic feature of the viruses has important implications concerning their mode of transmission and for understanding the etiology of acute gastroenteritis in adults.

Adult↗
PubMed1999

Seasonality and diversity of Group A rotaviruses in Europe.

Group A rotaviruses are a major cause of severe gastroenteritis in children under 4 y of age worldwide. Group A rotaviruses have been identified in many animal and bird species, they are antigenically complex, and multiple serotypes infect humans. Re-assortant rotavirus vaccines are now available which confer protection against severe illness due to rotavirus serotypes G1-4. Before vaccines are introduced it is necessary to establish the diversity of rotavirus in the target population to ensure efficacy and to establish a baseline for future surveillance strategies. The purpose of this review is to describe our current knowledge of the diversity of rotaviruses across Europe. Since multinational studies with standardized methodology have not been performed, this review is based on the available published studies. In Europe, more than 90% of Group A rotavirus strains that have been typed are of serotypes G1-4, with an average 8% of non-G1-4 strains in published studies. The percentage of non-typeable strains may fluctuate from one year to another, and has been as high as 18% in one study in Great Britain, indicating the need for a more systematic study. Group A rotavirus infection typically occurs as a winter peak in the European countries studied. Comparison of seasonality data from national laboratory surveillance systems showed seasonal differences, with the annual rotavirus peak occurring first in Spain, usually in December, followed by France in February, and ending in Northern Europe in England and Wales in February or March, and the Netherlands and Finland in March.

Child↗
PubMed1999

Epidemiology of rotavirus infections in The Netherlands.

This paper reviews published and unpublished data from epidemiological and virological studies of rotavirus in the Netherlands to identify gaps in our knowledge; it includes analysis of surveillance data for seasonality and age groups at risk. Rotavirus was found in approximately 5% of stool specimens from people consulting a physician for gastroenteritis. Of these cases, 38% were under 5 y of age. A clear seasonality was observed, with a peak in rotavirus activity in winter and early spring. In one hospital-based study between 1976 and 1983, rotavirus was found in 30% of children under 3 y of age hospitalized for gastroenteritis. In addition, nosocomial infections have been documented. Analysis of monthly data from laboratory surveillance from 1981 to 1996 showed that between 6 and 16% of stool samples tested positive for rotavirus, again with a clear seasonal distribution. A total of 98% of rotavirus strains that were typed were G-type 1-4. We conclude that more recent data about hospitalization rates are needed for a well-founded cost-benefit analysis.

Adolescent↗
PubMed1995

Evaluation of antigen and antibody detection in urine specimens from children with congenital human cytomegalovirus infection.

Fetal infection with human cytomegalovirus (HCMV) is the leading viral cause of brain damage among newborns at birth or later in life. Efforts to screen newborns routinely for shedding of the virus by immunoassay have been hampered by inhibitors in urine, reportedly the host protein beta2-microglobulin (beta 2m). An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of HCMV antigen in which the reactivity was not affected by the presence of beta 2m, but nevertheless inhibition was observed when urine samples with high levels of virus were tested. The presence of antibodies to HCMV was demonstrated in these urine samples by antibody ELISA and immunoblot using the major antigenic protein of HCMV (pp150) expressed in Escherichia coli; this offers an alternative explanation for the inhibition in ELISA. The presence of HCMV antibodies correlated significantly with congenital HCMV infection (as detected by tissue culture isolation of virus from urine samples of newborns), especially with asymptomatic cases (sensitivity 70%; specificity 94%). The data indicate a local (renal) immune response to HCMV in congenitally infected children, which may have future diagnostic applications.

Adult↗
PubMed1995

A case of family dysfunction and teenage suicide attempt: applicability of a family systems paradigm.

A large body of research indicates that suicidal behavior in adolescence is related to dysfunctional family processes. The purpose of this paper was to investigate this relationship focusing on the concepts of boundary transgression, double bind interactions, and the demarcation of kinship roles in the family. The possibility is explored that suicidal behavior is a double bind response to contradictions in the way roles and responsibilities are distributed in the family, and that as a response, suicide attempts may contain a simultaneous appeal for help and an assertion of independence from the family. A case vignette is presented to illustrate these processes.

Adolescent↗
PubMed1994

Self-reports of sexual abuse, mental health status, and perceived confusion of family roles: a retrospective study of college students.

This study examined the possibility that mental health problems which may result from sexual abuse are exacerbated by a confusion of family roles in the victim's perception of the family of origin. A sample of 234 undergraduate students completed a questionnaire. Analyses confirmed associations between (1) perceived sexual abuse and indicators of mental health problems, (2) confusion of family roles and perceived sexual abuse, and (3) mental health problems and confusion of family roles. A good prediction of the occurrence of mental health problems could only be obtained if both perceived sexual abuse and the confusion of family roles were considered.

Adaptation, Psychological↗
PubMed1993

An in-depth study of Crohn's disease in two French families.

BACKGROUND: Two French families were investigated. In the first a husband, wife, and 4 children had Crohn's disease; in the second 7 of 11 children had the disease. There was no history of Crohn's disease in antecedent generations and no linkage to HLA haplotypes. METHODS: Methods included family interviews; review of medical records, radiographs, and pathology slides; serology; selective stool culture; enzyme-linked immunosorbent assay for fecal viral detection; and immunocytochemistry. RESULTS: In both families multiple cases occurred among siblings in 7-13-month periods. There appeared to be a 4-8-year recurrence of new disease in both families. Radiographs showed a remarkable similarity in the pattern of disease, confined to distal ileum and cecum, in the members of family 1. Examination for pathology showed granulomas in all 8 patients for whom tissues were available. Acid-fast organisms or Campylobacter-like organisms were not found in tissue sections, and immunocytochemistry was negative for mycobacteria and Yersinia. Stool cultures were negative for mycobacteria, Yersinia, and Mycoplasma. Torovirus and coronavirus antigens were not found in stool. Serology was negative for antibodies to Brucella, Yersinia, influenza, and three enteropathogenic viruses of animals. CONCLUSIONS: The circumstances and data suggest that an infectious microorganism is responsible for these clusterings of Crohn's disease.

Adult↗
PubMed1993

Optimization of extraction and PCR amplification of RNA extracts from paraffin-embedded tissue in different fixatives.

A method was developed for fast and efficient isolation of RNA from paraffin-embedded tissue sections for subsequent PCR analysis. This method is based on the binding of RNA to acid-treated glass beads in the presence of a high molarity of guanidinium salt. It can be completed within an hour, and obviates the need for dewaxing and phenol/chloroform extractions. The effect of various fixatives and fixation times was tested and the amplification of actin mRNA fragments ranging in length from 82 to 507 bp was used to demonstrate the presence of RNA in the extracts. The method was compared to existing extraction techniques by studying the quality of the templates for reverse-transcriptase polymerase chain reaction amplification (RT-PCR), using virus-infected and mock-infected paraffin-embedded cell pellets as a model. PCR amplification of cellular and viral RNA was successful for RNA isolated by use of all extraction techniques, although the glass bead method was preferred for its simplicity and rapidity. Specimens fixed with formalin were found to be suitable for PCR, but the best results were obtained with acetone-fixed paraffin-embedded material. Dewaxing of tissue sections had no effect on the yield and quality of RNA extractions, and further purification of the extracts using gel filtration did not improve the results. After the protocols were optimized, rotavirus-infected cell pellets were used to demonstrate that extraction and amplification of dsRNA was possible. The information obtained from the studies with the model system was used for extraction of toroviral and rotaviral RNA from archival intestinal material. These data indicate that paraffin-embedded archival tissue can be used for RT-PCR analysis, adding an important technique to diagnostic pathology and retrospective studies.

Animals↗