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Biomedical subjects

A Groeneveld

Publications and source records attributed to A Groeneveld.

At least 19 recordsLinked to original sources
PubMed2002

Immune modulation by fish kinetoplastid parasites: a role for nitric oxide.

Trypanoplasma borreli and Trypanosoma carassii are kinetoplastid parasites infecting cyprinid fish. We investigated the role of nitric oxide (NO) in immune modulation during T. borreli and T. carassii infection of carp. Phagocytic cells from different organs produced NO and serum nitrate levels increased, demonstrating that T. borreli activates NO production in vivo. In contrast, T. carassii did not induce NO production in vivo and inhibited LPS-induced NO production in vitro. Production of NO was detrimental to the host as T. borreli-infected carp treated with the inducible NO synthase inhibitor aminoguanidine had a higher survival than infected control carp. This detrimental effect can be explained (in part) by the toxicity of NO to cells in vitro as NO inhibited the proliferative response of blood and spleen leukocytes. Head-kidney phagocytes were resistant to the immunosuppressive effects of NO in vitro. The NO-inducing activity of T. borreli may be an adaptation developed to ensure survival and immune evasion in the fish host. Apparently, T. carassii has adopted another strategy by deactivating specific functions of phagocytes. Both strategies may ensure long-term survival of the parasite.

Animals↗
PubMed2000

Molecular and functional characterization of a fish inducible-type nitric oxide synthase.

Using an oligonucleotide primer based on a partial goldfish inducible nitric oxide synthase (iNOS) sequence, a complete carp iNOS cDNA was isolated from an activated carp phagocyte cDNA library. Nucleotide and predicted amino acid sequence analysis indicate that carp iNOS encodes a 1,127-amino acid protein with 57% sequence identity to human iNOS. Like mammalian NOSs, carp iNOS protein contains putative binding sites for heme, tetrahydrobiopterin, calmodulin, flavine mononucleotide, flavine adenine dinucleotide, and NADPH. Phylogenetic analysis, using neighbor joining, showed that the carp iNOS protein clustered together with the other vertebrate iNOS proteins. Inducibility of carp iNOS was confirmed by reverse transcription-polymerase chain reaction after stimulation of carp phagocytes with lipopolysaccharide or the protozoan blood flagellate Trypanoplasma borreli. These stimulators produced high amounts of nitric oxide that were toxic for T. borreli in vitro. The nuclear transcription factor NF-kappaB was shown to play a role in the induction of iNOS transcription.

Amino Acid Sequence↗
PubMed1998

Analysis of epidemiological data on oral diseases in Nepal and the need for a national oral health survey.

This paper reviews and analyses the results of epidemiological studies on periodontal diseases and dental caries in Nepal and considers the need for additional data on oral diseases for the planning of a national oral health strategy. Almost all subjects aged 12 to 19 years (68-97 per cent) and 35 to 44 years (93-100 per cent) had calculus. The various studies showed that a median 29 per cent of subjects aged 35-44 years had deep periodontal pockets. According to this estimate it can tentatively be concluded that Nepal belongs to the 15 per cent of countries in the world where periodontal conditions of the population are among the worst. An accurate DMFT-value for different age groups at present cannot be estimated due to period and sampling effects. The observed cohort effect over time suggests that caries has increased in the 12-19 years age group in Nepal in the period 1980-1996. The estimated range of DMFT-values for 12 years old children is between 0.6-1.9 and for 35 to 44 years old persons between 2.5-4.0. With these DMFT-values Nepal belongs to the countries with a 'low to very low' caries experience according to the WHO decay rating. The present epidemiological data do not justify a claim for a national oral health survey as a starting point for a national plan of oral health since more accurate data do not add additional value to that planning, particularly not in poor countries as Nepal where the oral health service is still in its infancy.

Adolescent↗
PubMed1996

Multiple regulation of carp (Cyprinus carpio L.) macrophages and neutrophilic granulocytes by serum factors: influence of infection with atypical Aeromonas salmonicida.

Normal carp serum contains inhibitory and stimulatory factors for macrophage and neutrophilic granulocyte respiratory burst activity. As stimulatory factors were only effective in combination with phorbol myristate actetate (PMA) activation, it is concluded that they are probably linked to protein kinase C activation. Both the stimulatory and inhibitory factors are heat stable. Macrophage- and neutrophilic granulocyte-enriched cell fractions from the pronephros of carp had high respiratory burst- and high bactericidal in vitro responses to virulent atypical Aeromonas salmonicida bacteria. Serum factors were inhibitory for the A. salmonicida induced respiratory burst activity. No change in inhibitory or stimulatory serum factors could be observed during a 12-day challenge experiment with A. salmonicida, or during a rechallenge of survivors from a previous sub-lethal infection. The sensitivity of macrophages and neutrophilic granulocytes to stimulation of respiratory burst activity by PMA was not significantly altered. Culture supernatants from PHA pre-treated lymphocytes stimulated the respiratory burst activity of macrophages and neutrophilic granulocytes suggesting that serum factors may partially be lymphocyte derived.

Aeromonas↗
PubMed1996

Characterization of isogenic carp (Cyprinus carpio L.) lines with a genetically determined high or low antibody production.

Antibody production to dinitrophenyl-keyhole limpet haemocyanin (DNP-KLH) served as the immune parameter to divergently select carp (Cyprinus carpio L.) to produce high- and low-responder F1 hybrid lines. Antibody production to trinitrophenyl-lipopolysaccharide (TNP-LPS) and to DNP-KLH were similar in magnitude. By contrast, some high-responder lines were low responders to DNP-human serum albumin, and vice versa. Low-responder carp were relatively susceptible to infection with the parasite Trypanoplasma borreli. This suggested that at least one gene with a major influence on resistance differed between the two homozygous parents (69, 85) used to generate the high- and low-responder homozygous families, respectively. The isogenic lines showed no within-line variation in DNA fingerprints, but differed with respect to their MhcCyca-DAB genes.

Animals↗
PubMed1995

Genetic variation in susceptibility to Trypanoplasma borreli infection in common carp (Cyprinus carpio L.).

Gynogenetic reproduction of homozygous females, or crossbreeding two homozygous animals, results in fish lines without genetic variation. Hybrid crosses are expected to express a more stable development than homozygous lines, the latter may have an important value for gaining insight into genetic components of host resistance to parasite infection. We examined the antibody response of carp (Cyprinus carpio L.) to infection with Trypanoplasma borreli. Outbred carp responded with a production of specific antibodies, but highly susceptible isogenic hybrid carp did not. This suggests an apparent relationship between susceptibility and the lack of specific antibody production. This relation was partially confirmed by the passive transfer of immunity with immune plasma. In addition, two isogenic homozygous carp lines were highly susceptible to the trypanoplasm (100% mortality), in contrast with outbred carp, the majority of which survived infection. None of the carp in either homozygous carp line produced an antibody response to parasite-unrelated antigen (DNP-KLH). This suggests that the low antibody response was not entirely due to a poor state of health, but that these carp have a genetically predetermined low antibody response.

Animals↗
PubMed1994

CHARACTERIZATION OF MACROPHAGES AND NEUTROPHILIC GRANULOCYTES FROM THE PRONEPHROS OF CARP (CYPRINUS CARPIO)

To analyse the functional activity of different leucocyte types, carp pronephros cells were separated on Percoll density gradients and by use of fluorescence-activated cell sorting. Cell populations were characterised by light and electron microscopy and by flow cytometry. Fractions enriched in macrophages and neutrophilic granulocytes were subsequently analysed for phagocytic activity in vitro by quantification of the uptake of Escherichia coli bacteria or yeast cells, and for respiratory burst response by measurement of the production of the reactive oxygen intermediates O2· and H2O2. Both cell types showed very active in vitro phagocytosis and production of both O2· and H2O2. When activated with phorbol myristate acetate or bacteria, it was evident that the neutrophilic granulocytes were significantly more active than the macrophages. Analysis of single-cell respiratory burst activity in fish phagocytes was investigated after preloading of cells with dihydrorhodamine123. Cells were subsequently separated and analysed for fluorescence using flow cytometry. Both the macrophage-enriched fraction and the granulocyte-enriched fraction appeared to consist of active and inactive subpopulations. In comparison with the inactive populations, active populations had characteristic high forward/sideward scatter profiles.

Journal Article↗
PubMed1993

Relationships between birefringence and mineral content in artificial caries lesions of enamel.

The microradiographic mineral content and birefringence in water and Thoulet's solution were measured at selected points in sections of caries-like lesions. Birefringence was not related to mineral content in sound superficial enamel immersed in Thoulet's solution or in the lesion body immersed in water. For the surface layer of the lesion, birefringence in water could be used to obtain qualitative information about mineral content. For the lesion body, birefringence in Thoulet's solution was linearly related to mineral content and can be used to estimate the latter with a standard error of about 7 vol%. The intrinsic birefringence for the lesion body was estimated as -34.5 (+/- 2.3) x 10(-4); This value may also be valid for other parts of the lesion. From consideration of ionic sizes, it is argued that Thoulet's solution cannot necessarily penetrate all enamel pores accessible to water. It appeared that there is a progressive fall in the content of pores inaccessible to Thoulet's solution in the surface layer of the lesion as demineralisation increases.

Birefringence↗
PubMed1993

Caries experience of 15-year-old children in The Netherlands after discontinuation of water fluoridation.

In 1973 the fluoridation of drinking water in the Dutch town of Tiel was discontinued. In order to monitor the effect of this measure, the caries experience in 15-year-old children was investigated annually from 1979 to 1988, both in Tiel and in Culemborg. In the latter town the drinking water had never been fluoridated. The caries data of 15-year-old children examined between 1968 and 1969 in Tiel (children having used fluoridated water from birth) and Culemborg were used as historical controls. In Tiel the mean number of DMFS increased between 1968/69 and 1979/80 from 10.8 to 12.7 (+18%) and decreased to 9.6 (-26%) in the following years; in 1987/88 the mean DMFS was 11% lower than in 1968/69. In Culemborg the mean DMFS score decreased between 1968/69 and 1987/88 from 27.7 to 7.7 (-72%). In 1968/69 the mean DMFS score in Tiel was 61% lower and in 1987/88 17% higher than in Culemborg. The question as to whether water fluoridation would have had an additional effect if it had been continued (presuming the application of existing preventive measures) cannot be answered, as there are no remaining communities with fluoridated water in The Netherlands.

Adolescent↗
PubMed1992

Monoclonal antibody MON-114: detection of a marker for neuroendocrine differentiation in human lung cancer.

Mouse monoclonal antibody MON-114 was generated upon immunization with a human small cell lung carcinoma cell line GLC-19. Immunohistochemical analysis of normal tissues with MON-114 showed staining of the adrenal gland, brain and peripheral nerves. With respect to human lung carcinomas, 7 out of 8 small cell lung carcinomas were positively stained as well as 5 out of 5 carcinoid tumors, whereas only 4 out of 31 squamous cell carcinomas and 3 out of 19 adenocarcinomas were weakly stained. Furthermore, 1 large cell carcinoma was negative for MON-114 staining. Apparently, MON-114 stains cells of neuroendocrine differentiation.

Animals↗
PubMed1992

MON-150, a versatile monoclonal antibody against involucrin: characterization and applications.

A monoclonal antibody, designated MON-150, was found serendipitously to react strongly with the granular layer of normal human epidermis and with the upper spinous layers of psoriatic epidermis. From analysis by flow cytometry of cultured human keratinocytes, it appeared that the percentage of MON-150-positive cells strongly increased when the cells reached confluence and the growth fraction declined. To identify the antigen recognized by MON-150, a lysate of human keratinocytes was subjected to affinity chromatography using a MON-150 Sepharose column. This yielded a single protein of approximately 350 kDa as measured on Superose 6 FPLC gel permeation chromatography using non-denaturing conditions. In Western blot analysis under denaturing and reducing conditions, a 140-kDa protein was detected. The subcellular localization and the molecular weight of the antigen recognized by MON-150 suggested that the antigen involved might be involucrin. This was confirmed using a commercial polyclonal antiserum against involucrin. We conclude that MON-150 is a new, versatile antibody against human involucrin.

Antibodies, Monoclonal↗
PubMed1992

Development and characterization of a panel of monoclonal antibodies against the novel subtilisin-like proprotein processing enzyme furin.

Monoclonal antibodies were raised against the recently discovered subtilisin-like proprotein processing enzyme furin. As immunogen, a bacterially expressed hybrid protein was used which consisted of glutathione S-transferase fused to almost the entire human furin protein. Ten monoclonal antibodies were obtained and these could be divided into four categories on the basis of their reactivity towards a number of bacterially expressed hybrid proteins, each of which contained a different portion of human furin. Four of the monoclonal antibodies did not recognize mouse furin. All monoclonal antibodies were tested for their applicability in Western blot and immunofluorescence analysis. Western blot analysis was performed with COS-1 cells in which biologically active forms of human and mouse furin were expressed transiently under control of the SV40 late promoter. This approach was necessary, since physiological levels of fur gene encoded proteins appeared to be very low. In cells transfected with human or mouse fur cDNA, a protein of about 100 kDa and a doublet of about 90 kDa could be detected with most of the monoclonal antibodies. Some of these antibodies appeared to be also reactive in immunofluorescence analysis of transfected COS-1 cells.

Animals↗
PubMed1992

[Cessation of fluoridation of drinking water; results of caries research in Tiel and Culemborg in the period of 1968-1988].

In December 1973 water fluoridation was discontinued in Tiel, the Netherlands. Six years later an epidemiological study was started, with the aim to investigate the consequences. In the period from 1979 to 1988 a yearly caries investigation was carried out in 15 year old children born and living in Tiel and children living in the control town of Culemborg, where the drinking water had never been fluoridated. The 15 year old children in 1979-1980 in Tiel had a 18% higher caries experience than the same age group in 1968-1969, to whom fluoridated water had been available from birth onward. In the same period a 28% decrease of the caries was found in Culemborg. In 1979-1980 the DMFS-index in Tiel was still 36% lower than in Culemborg. Between 1979-1980 and 1987-1988 the caries experience decreased in both towns.

Administration, Oral↗
PubMed1992

Ketamine. A solution to procedural pain in burned children.

Our experience has shown ketamine to be a safe and effective method of providing pain relief during specific procedures in burned children. It renders high doses of narcotics unnecessary and offers children the benefit of general anesthesia without the requirement of endotracheal intubation and a trip to the operating room. The response of parents and staff to the use of ketamine has been positive. Parents often experience feelings of guilt following injury to a child and are eager to employ methods that reduce their child's pain. So far, no parent has refused the administration of ketamine; some have even asked that it be used during subsequent procedures on their child. With adequate pre-procedure teaching, parents are prepared for the possible occurrence of emergent reactions and can assist in reorienting the child during recovery. Staff have found that the stress of doing painful procedures on children is reduced when ketamine is used. The procedures tend to be quicker and the predicament of working on a screaming, agitated child is eliminated. At the same time, nursing staff have had to get used to the nystagmic gaze of the children and accept that these patients are truly anesthetized even though they might move and talk. Despite the success we and others have had with ketamine, several questions about its use in burn patients remain unanswered. The literature does not answer such questions as: Which nursing measures reduce the incidence of emergent reactions? How many ketamine anesthetics can safely be administered to one individual? How does the frequency of administration relate to tolerance in a burn patient? Are there detrimental effects of frequent or long-term use? Clearly, an understanding of these questions is necessary to determine the safe boundaries of ketamine use in burn patients. Ketamine is not a panacea for the problem of pain in burned children. But it is one means of managing procedural pain, which is, after all, a significant clinical factor in treatment and recovery.

Burn Units↗
PubMed1991

Application of recombinant DNA technology in epitope mapping and targeting. Development and characterization of a panel of monoclonal antibodies against the 7B2 neuroendocrine protein.

Three mouse monoclonal antibodies (Moabs) have been obtained with specificity for the 7B2 protein, a proposed member of the granin family of neuroendocrine proteins. Bacterially produced hybrid proteins of 7B2 were used as immunogens. The Moabs were designated MON-100, MON-101, and MON-102. Furthermore, we report the construction of 35 deletion mutants of the glutathione S-transferase-7B2 (GST-7B2) fusion-gene using recombinant DNA technology. The hybrid proteins encoded by eleven of these mutants were used in epitope mapping experiments and the results of these studies strongly suggested that recognition of 7B2 by all three Moabs involved the same 16 amino acid region of 7B2 (from amino acid residue 128-135). This was further substantiated by the observation that MON-101 and MON-102 specifically recognized a conjugate between bovine serum albumin and the synthetic peptide Phe-Glu-Pro-Glu-His-Asp-Tyr-Pro-Gly-Leu-Gly-Lys based upon the deduced amino acid sequence of the predicted epitope region in 7B2. In an approach to generate a series of 7B2-specific Moabs targeted against another epitope region in the 7B2 protein, the hybrid protein encoded by deletion mutant pPV32 was used as the immunogen. This protein lacked the epitope region recognized by the first series of Moabs. A second series of three Moabs, designated MON-142, MON-143, and MON-144, was obtained and, in all three cases, the region of 7B2 from amino acid residue 64-94 appeared to be involved in specific recognition by the Moabs. The whole panel of six anti-7B2 antibodies appeared to be useful in immunoprecipitation and Western blot analysis of the 7B2 protein and specifically stained neuroendocrine cells in immunohistochemical experiments. Using a double determinant sandwich enzyme immunoassay, 7B2 protein levels in rat pituitary were determined as 20 ng/mg tissue.

Amino Acid Sequence↗
PubMed1990

Depth of occlusal caries assessed clinically, by conventional film radiographs, and by digitized, processed radiographs.

Occlusal caries depth was assessed in 47 extracted premolars and permanent molars by 4 observers on a rank scale by eye inspection, by film radiographs, and by 2 of the observers also by digitized radiographs after filtering and contrast enhancement of the image. Quantitative estimates of caries depth were obtained from the digitized radiographs. Accuracy of scorings was determined with the histologic section as validating criterion. Occlusal caries was present in a spectrum from incipient fissure decalcification to large cavity formation. Clinical as well as radiographic scorings most frequently under-estimated lesion depth. Accuracy of radiographic assessments increased substantially by digital processing of the radiographic image. Quantitative measures of caries depth on digitized radiographs were strongly correlated to the histologic measures (r = 0.91). Interobserver agreement was fair to moderate according to kappa coefficients for the clinical and the radiographic scorings. The agreement was highest for the scorings of the digitally enhanced images. The study suggests that digital processing of radiographic images constitutes a diagnostic aid that may give a more accurate estimate of occlusal caries depth.

Analog-Digital Conversion↗
PubMed1990

Fluoride in caries prevention: is the effect pre- or post-eruptive?

A longitudinal study of children from ages 7 to 18 showed that, if enamel lesions were included, the overall number was the same in fluoridated and non-fluoridated areas. However, a significant reducing effect of pre-eruptive fluoride could be seen in the number of dentinal lesions in a fluoridated area, provided that fluoride was also consumed post-eruptively for a considerable period of time. A precise estimation of both pre- and post-eruptive effects was obtained when teeth were classified according to their eruption time as related to the onset of water fluoridation. About 66% of the greatest reduction in pit and fissure caries came from pre-eruptive fluoride, while in smooth surfaces, this effect was reduced to 25%. In approximal surfaces, the reduction was due half to pre- and half to post-eruptive fluoride. Post-eruptive fluoride became more important with decreasing severity of caries attack. Thus, assuming a continuing decline in dental caries, the majority of such populations will benefit most from the use of topical fluorides. However, in high-risk groups, supplementation of pre-eruptive fluoride can still be of major importance.

Child↗