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Biomedical subjects

J De Boever

Publications and source records attributed to J De Boever.

At least 19 recordsLinked to original sources
PubMed2001

Expression of Ly49E and CD94/NKG2 on fetal and adult NK cells.

Murine NK cells express inhibitory receptors belonging to the Ly49 and CD94/NKG2 family. Ly49E and CD94 are the only NK cell receptor transcripts detectable in fetal NK cells. Still unproved is the surface expression of Ly49E on NK cells. Here we generated two novel mAbs, a mAb recognizing Ly49E with cross-reactivity to Ly49C, and a mAb against NKG2A/C/E. Ly49E was immunoprecipitated as a disulfide-linked homodimer with 46-kDa subunits. Removal of N-linked carbohydrates revealed a 31-kDa protein backbone. NKG2A was immunoprecipitated as a 38-kDa protein. Although the frequency of fetal NK cells expressing Ly49E was higher than 25%, it decreased drastically from 2 wk after birth. Phenotypic analysis showed that approximately 90% of fetal NK cells and approximately 50% of adult NK cells express high levels of CD94/NKG2. The remaining 50% of adult NK cells expressed low surface levels of CD94/NKG2. Expression of Ly49E and CD94/NKG2 was not restricted to NK cells, but was also observed on NK T and memory T cells. Functional analysis showed that sorted Ly49E(+) and CD94/NKG2(+) fetal NK cells could discriminate between MHC class I-positive and MHC class I-negative tumor cells. We also demonstrated that Ly49E becomes phosphorylated following pervanadate stimulation of fetal NK cells. The expression levels of Ly49E and CD94/NKG2 were similar in wild-type compared with beta(2)-microglobulin(-/-) mice. In conclusion, generation of mAbs against Ly49E and NKG2 extended the phenotypic and functional characterization of NK cells.

Aging↗
PubMed2000

The involvement of the styloid process in head and neck pain--a preliminary study.

The styloid process and associated structures have been implicated in a variety of craniomandibular dysfunctions and pain complaints. There have been anecdotal reports that treatment directed at this area can result in a dramatic reduction in referred symptoms, somatic pain and autonomic signs as well as an increase in mandibular range of motion. In the past, an elongation of the styloid process was considered necessary for pain and dysfunction symptoms to arise from this area. The patients in this study did not have elongated styloid processes, yet had orofacial pain and dysfunction symptoms seemingly referred from this area. An injection of local anaesthetic and corticosteroid in the area of the styloid process significantly reduced lateral head pain and improved mandibular function in spite of an absence of any demonstrable pathology at the styloid process.

Adolescent↗
PubMed1999

Murine fetal natural killer cells are functionally and structurally distinct from adult natural killer cells.

Natural killer (NK) cell phenotype and activity was studied by analyzing uncultured and short-time-cultured murine NK cells from fetal day 17 spleen and thymus. In contrast to NK cells from adult mice, freshly sorted fetal NK cells did not contain NK receptor transcripts for Ly-49A, B, C/I, D, F, G2, or H. The only NK receptor transcripts that could be detected were Ly-49E and CD94. It is important that Ly-49E was present at a 10- to 30-fold higher level compared with uncultured NK cells from adult mice. After short-time interleukin-2 culture, the level of Ly-49E mRNA was comparable between fetal and adult NK cells. Functionally, fetal NK cells only killed MHC class I-negative tumor cells when activating NK receptors were cross-linked with antibody. We show that fetal NK cells are mature but are different from NK cells in adult mice regarding their NK cell receptor repertoire and function.

Animals↗
PubMed1995

A direct non-competitive idiometric enzyme immunoassay for serum oestradiol.

We report a novel non-competitive enzyme immunoassay for oestradiol based on the use of two types of anti-idiotypic antibody that recognize different epitopes within the hypervariable region of the primary anti-oestradiol idiotypic antibody (Ab1). The first anti-idiotype, the betatype, competes with the analyte for an epitope of the primary antibody at the binding site. On the other hand, the second anti-idiotype, the alphatype, binds to the Ab1 in the presence of analyte but does not bind to the betatype/Ab1 complex because of steric hindrance. In the present format the biotinylated alphatype was captured onto anti-biotin IgG which was adsorbed on the surface of microtitre wells. Reaction mixtures containing the Ab1 complexed sequentially with an enzyme labelled second antibody reagent, with oestradiol standards or serum samples and with the betatype anti-idiotypic antibody were then allowed to react with the immobilized alphatype anti-idiotypic antibody. The enzyme activity of the bound fraction measured at 405 nm increased with increasing oestradiol concentrations over the range 0.06-2.5 ng/ml. The detection limit of the assay was 28 pg/ml. The intra-assay variation ranged from 3.5 to 12.4%, and inter-assay variation from 6 to 13.4%. The results obtained by the colorimetric idiometric immunoassay correlated well with those obtained by a direct radioimmunoassay (n = 85, r = 0.97). This non-competitive immunoassay, termed idiometric assay, for haptens permits the development of sensitive immunoassays with a wide working range, and a variety of end-point determinations depending on the label used (e.g., enzyme, chemiluminescent or fluorogenic compound).

Animals↗
PubMed1995

The measurement of progesterone in serum by a non-competitive idiometric assay.

A novel non-competitive idiometric time-resolved fluoroimmunoassay for the determination of serum progesterone was developed, based on the use of two types of anti-idiotypic antibody that recognize different epitopes within the hypervariable region of the primary antiprogesterone antibody. The first anti-idiotype, the betatype, competes with progesterone for an epitope of the primary antiprogesterone antibody at the binding site. The second anti-idiotype, the alphatype, binds to the antiprogesterone antibody in the presence of progesterone, but does not bind to the betatype antiprogesterone complex due to epitope proximity. In the present configuration, the biotinylated alphatype was captured onto anti-biotin IgG which was immobilized on microtiter wells. Reaction mixtures containing europium-labeled antiprogesterone antibody complexed sequentially with progesterone in standards or serum samples and with the betatype anti-idiotypic antibody were then reacted with the immobilized alphatype anti-idiotypic antibody. After 30 min of incubation, the fluorescence of europium is measured by time-resolved fluorescence and is proportional to the concentration of progesterone over the range 0-320 nmol/mL. The method demonstrates good sensitivity, precision, and comparability with a direct competitive radioimmunoassay. The idiometric assay for progesterone is suitable for dipstick technology and biosensors.

Antibodies, Anti-Idiotypic↗
PubMed1995

[The problem of cross infection and risk of infection for the practitioner].

Epidemiologic data show that in Belgium, the number of HIV-infected persons increases with an average of 3 a day. This increase will pose a real problem to all health workers including the dentists. The chance that the general dental practitioner comes in contact with HIV-infected patients will increase in the years to come. Therefore, each dental practitioner should have a scheme in his office to prevent cross infection. The transmission of HIV is analogue to HBV: blood, blood products, injury, wound, use of non-sterile instruments and needles... Transmission of HIV by saliva has not been proved yet. Both viruses have the same route of transmission but with a different probability, due to the difference of viral particles per ml plasma. The average chance of transmission from patient to health care worker for HIV is 0.5%, for HBV 6 to 30%. The probability of HIV transmission from a HIV-infected dentist to his patient during one invasive procedure is 3.8 x 10(-6) - 3.8 x 10(-8). In spite of this (low) chance precautions are a prerequisite. On one hand the health care worker has to protect himself and the assistant, on the other hand it's his duty to protect the patient whose immune system is deficient for infection. In this paper a practical approach for the general dental practitioner is proposed. The authors stress the use of exact sterilisation technics, the use of sterile clothes and gloves and the routine uses of glasses and a mask. One of the most important problems, the handling of the infected and contaminated waste, has not been properly solved. Only for medical institutions and hospitals, strict rules have been adopted by the Belgian Government. However, rules and laws for the handling of contaminated material of dental offices have not been published yet.

Adult↗
PubMed1995

[Drug-induced gingival proliferation: overview of etiology and treatment].

Cyclosporine, substituted Dihydropyridines and Phenytoin are three drugs that are often correlated with gingival overgrowth. Differences in incidence and histology are reviewed. Due to the large range of illnesses for which these drugs are prescribed, we can only anticipate a high increase in the number of patients who seek treatment for their enlarged gums. Contemporary treatment modalities are changing towards increased usage of these pharmaceutics which will lead to a high frequency of patients which have drug induced alterations of their gingival structures. The dental practitioners will also need to be consulted prior to drug treatment so that preventive measures can be taken. Treatment of gingival overgrowth is discussed.

Adolescent↗
PubMed1994

[Retention of adhesive bridges].

Since the development of adhesive bridges in the early seventies, the retention and therefore the durability of these bridges has been tremendously improved. Conditioning of the non-precious metal by silanisation, careful acid etching of the enamel and the use of the appropriate composite resin are of prime importance. Furthermore, the meticulous preparation with enough interproximal embrace, occlusal rests, interocclusal clearance and cingulum stops is equally important. Including more teeth in the design does not necessarily lead to an improved retention. Besides the material and technical aspects, the whole clinical procedure needs much attention. The retention does not depend on one single factor, but on the precision of all the necessary clinical steps and on a well-defined selection of the material. In this way a five-year survival rate of close to 80% can be obtained.

Acid Etching, Dental↗
PubMed1993

Subgingival minocycline hydrochloride ointment in moderate to severe chronic adult periodontitis: a randomized, double-blind, vehicle-controlled, multicenter study.

The safety and efficacy of subgingivally-applied 2% minocycline ointment was evaluated in a randomized, double-blind study of 103 adults with moderate to severe periodontitis. Two groups were compared; one received the test minocycline ointment and the other a vehicle control. Both groups had scaling and root planing at baseline, after which the test or control ointments were applied with an applicator into the periodontal pockets at baseline, and at 2, 4, and 6 weeks. Assessment of clinical response was made by measuring probing depth and probing attachment level and gingival bleeding. These measurements were made at baseline prior to scaling and root planing, and at weeks 4 and 12. Microbiological assessment of the subgingival flora was carried out with DNA probes at baseline, and at weeks 2, 4, 6, and 12 to identify and quantify Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans. Subgingival minocycline ointment resulted in statistically significantly greater reduction of P. gingivalis at weeks 2, 4, 6, and 12; P. intermedia at weeks 2, 4, 6, and 12; and A. actinomycetemcomitans at weeks 6 and 12. Probing depth reductions were seen for both groups at weeks 4 and 12; however, this reduction was statistically significantly greater in subjects treated with minocycline ointment. Reduction in gingival index and probing attachment gain were seen in both groups, however, the differences between the groups were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1992

Direct enzyme immunoassay of estradiol in serum of women enrolled in an in vitro fertilization and embryo transfer program.

We present a fast and simple direct enzyme immunoassay for the sexual steroid hormone estradiol-17 beta in serum of women enrolled in an in vitro fertilization and embryo transfer program. We added 25 microL of standards or samples and 125 microL of a mixture of monoclonal antibody and displacing agents to the wells of a microtiter plate previously coated with a second antibody. After 30 min 50 microL estradiol-horseradish peroxidase conjugate is added. Total incubation time is 75 min. The immunoassay is stopped by washing the microtiter plate. The amount of bound conjugate is then measured at 450 nm with hydrogen peroxide as a substrate and 3,3',5,5'-tetramethylbenzidine as chromogen. The detection limit is 0.24 nmol/L. The assay is thus limited in its application. Analytical recovery is 90.8% (range 80.4-102.9%); within- and between-assay CVs range between 1.3% and 15.4%. Total assay time, including preparation of reagents and data reduction, is only 2.5 h. Results of this enzyme immunoassay compare well with those obtained with four different commercial radioimmunoassays (r = 0.88-0.93).

Embryo Transfer↗
PubMed1990

Correlation between peripheral CA-125 levels and ovarian activity.

Serum CA-125 concentrations were measured at three different times in normal cycles, pill-suppressed cycles, and cycles stimulated for intrauterine insemination (IUI) or oocyte retrieval, i.e., (1) during the first half of the cycle, (2) at midcycle or at the moment of oocyte retrieval, and (3) the second half of the cycle. Significant variations of serum CA-125 concentrations were not seen during the cycle in normally cycling women or in women taking oral contraceptives: mean +/- SD 28.9 +/- 13.3 U/mL and 26.9 +/- 11.3 U/mL, respectively. In patients stimulated for in vitro fertilization, luteal phase CA-125 levels (60.6 +/- 38 U/mL) were significantly higher than during stimulation (21.5 +/- 5.9 U/mL) or at oocyte retrieval (19.6 +/- 6.4 U/mL). In stimulated cycles for IUI, without laparoscopy or follicular puncture, a comparable rise of CA-125 was observed in the luteal phase (49.6 +/- 37.8 U/mL). However, in patients undergoing laparoscopic sterilization, serum CA-125 concentrations before and after laparoscopy were not significantly different (22.8 +/- 6.3 U/mL and 25 +/- 4.2 U/mL, respectively).

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1990

[Retention of adhesive bridges].

Since the development of adhesive bridges in the early seventies, the retention and therefore the durability of these bridges has been tremendously improved. To ensure an adequate retention over a number of years different factors have to be considered. Conditioning of the non-precious metal by silanisation, careful acid etching of the enamel and the use of the appropriate composite resin (Panavia Ex) are of prime importance. Furthermore, the meticulous preparation with enough interproximal embrace, occlusal rets, interocclusal clearance of 0.4 mm and cingulum stops is equally important. Care should be taken not to remove all the enamel in the cervical region in preparing a mini chamfer. Including more teeth in the design does not necessarily lead to an improved retention. Teeth with a different mobility should not be included in the same bridge. Besides the material and technical aspects, the whole clinical procedure needs much attention. Only an exact impression, a precise model and a reliable casting technique will provide a metal frame with an optimal marginal adaptation and a close fit. The retention does not depend on one single factor but on the precision of all the necessary clinical steps and on a well-defined selection of the material. In this way a five-year survival rate of close to 90% can be obtained.

Acid Etching, Dental↗
PubMed1990

Direct chemiluminescence immunoassay of estradiol in saliva.

A sensitive and simple direct solid-phase chemiluminescence immunoassay is described for estradiol in saliva. In this assay, a second antibody is bound to the wells of microtiter plates. Either buffer with standards or saliva (100 microL) is incubated in these wells with monoclonal anti-estradiol antibody and with estradiol-isoluminol conjugate. Incubation time is 2 h. Chemiluminescence of the bound fraction is measured in a manually operated luminometer (Biocounter). The assay has a detection limit of 3.8 pmol/L; analytical recovery of added estradiol is 96.8% (SD 7.0%); within- and between-assay CVs range between 2.5% and 12.7%. Forty unknown saliva samples can be assayed and results calculated within 4.5 h. Results of a slightly modified procedure-with black microtiter plates and a prototype of an automated plate reader (Luminoskan)--compare well with those of the described method (r = 0.97). Because steroid-binding globulins have been found in saliva, the effect of displacing agents on the results of the direct chemiluminescence assay is described.

Estradiol↗
PubMed1989

The expression of the neu oncogene product in breast lesions and in normal fetal and adult human tissues.

The expression of the neu oncogene product was investigated in invasive and non-invasive ductal carcinomas of the breast, non-neoplastic lesions of the breast, fragments of normal adult and fetal breasts and in several other normal and fetal tissues at different weeks of pregnancy by means of an immunohistochemical study with monoclonal antibodies. The staining pattern along the cytoplasmic membrane was specific for malignancy and occurred in 29% of the breast carcinomas. It was observed in invasive carcinomas as well as in ductal carcinoma in situ and it showed a significantly higher expression in premenopausal women than in postmenopausal women. This higher expression was also present in oestrogen receptor-negative tumours. The tubules of the fetal and adult kidney, the absorption cells of the fetal and adult small and large intestine, the sebaceous glands of the fetal and adult small and large intestine, the sebaceous glands of the fetal and adult skin, the adult endocervix, the endometrium, the C-cells of the thyroid, hepatocytes and all ductal cells of the fetal breast showed a constant diffuse intracytoplasmic granular staining. staining. The same granular intracytoplasmic staining pattern was focally observed in rare cases of normal breast tissue in adults and in some cases of epitheliosis, aprocrine metaplasia and some breast carcinoma cells, which did not express neu oncogene product on their membrane. Western blot experiments showed that the cytoplasmic protein had a molecular weight of 155 kD (kilodaltons); the membrane protein is the known 185 kD neu protein.

Adult↗
PubMed1987

Recent advances in chemiluminescence-based immunoassays for steroid hormones.

Several formats of solid-phase separation techniques for the measurement of steroids and urinary steroid conjugates using chemiluminescence as an end point are described. These formats include: (1) immunoadsorption of second antibodies directed against the first antibody on solid support; (2) specific immunoadsorbents consisting of primary antibodies covalently coupled to polymer beads; (3) second antibody coupled to a polymer containing magnetic particles. In these assays a steroid-chemiluminescent marker conjugate serves as the labelled ligand, and highly specific homologous monoclonal antibodies are used to provide optimal specificity and rigorous standardization. These techniques enabled the direct measurement of steroid glucuronides in diluted urine and of steroids in plasma.

Animals↗