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Biomedical subjects

M E Boon

Publications and source records attributed to M E Boon.

At least 73 records · Page 4Linked to original sources
PubMed1994

Involving the general practitioner in screening for cervical cancer.

In the Leiden region, the cervical cancer screening programme for the age group 35-54 years shifted in 1989 from one in which the smears were taken by specially trained paramedical personnel in health centres to a programme where the general practitioner is the smear taker. Hence, it is possible to compare the results of the two types of screening to evaluate whether involvement of general practitioners leads to better uptake of screening. In the 6 year period evaluated in this paper, the 3-yearly cytological rate per thousand for severe dysplasia or worse increased from 1.00 to 3.40; when stratified by age the positive rates were significantly higher. The histological rate per thousand for severe dysplasia increased from 0.60 to 2.09, and for carcinoma in situ from 0.35 to 1.36. All six invasive carcinomata were detected in the GP programme (0.31%). The general practitioner is clearly more able to attract the 'high-risk' groups.

Adult↗
PubMed1994

Detection of the BC 24 transforming fragment of the herpes simplex virus type 2 (HSV-2) DNA in cervical carcinoma tissue by polymerase chain reaction (PCR).

The polymerase chain reaction (PCR) was used to investigate samples from Indonesian and Swedish patients with cervical intraepithelial neoplasia grade III (CIN III), squamous cell carcinoma or adenocarcinoma of the cervix for the presence of a transforming fragment (BC 24) of herpes simplex virus type 2 (HSV-2) DNA. The PCR test for HSV-2 DNA was more sensitive than the infectivity endpoint titer in a cell culture system and no cross reactivity was found with either varicella-zoster virus, cytomegalovirus, Epstein-Barr virus, human papillomavirus 16 or 18, or human genomic DNA. Using this PCR test, 2 out of 5 cases with CIN III, 10 of 71 squamous cell carcinomas, and 3 of 11 adenocarcinomas of the uterine cervix were found to contain DNA sequences homologous to the BC 24 fragment of the HSV-2 genome. Only two of the samples containing this transforming region of the HSV-2 DNA were positive in a PCR assay for the HSV-2 DNA polymerase gene. The great majority of the HSV-2 BC 24 DNA positive (12 of 15) came from the Indonesian group of patients. All 15 CIN III or cancer samples positive for the HSV-2 BC 24 fragment were also positive for papillomavirus DNA. In line with observations made by others, our data support the hypothesis that HSV infection could represent one of several possible oncogenic cofactors leading to cervical carcinoma. The HSV cofactor might be more important in the Indonesian than in the Swedish population.

Adenocarcinoma↗
PubMed1994

Neural network processing of cervical smears can lead to a decrease in diagnostic variability and an increase in screening efficacy: a study of 63 false-negative smears.

A realistic approach for decreasing the number of erroneous diagnoses plaguing cervical cytology screening is to try to reduce the amount of nondiagnostic visual information. The neural network of PAPNET selects 128 cytological views from the routinely prepared smear which in digitized form can be displayed on a high-resolution videoscreen. From these 128 videotiles the abnormal ones can be selected by the diagnostician and brought together on the "summarizing videoscreen" containing 16 tiles. Thus, the diagnostic information can be further condensed. This facilitates the proper interpretation of the diagnostic cell material dispersed over the smear. A series of 63 false-negative smears were rescreened twice conventionally and twice using the PAPNET-assisted method. We found that, using PAPNET, the screening efficacy increased and the diagnostic variability decreased. The PAPNET in particular proved to be superior for smears containing few abnormal cells and cases of malignancies of the reserve cell lineage.

Adult↗
PubMed1994

Effect of embedding methods versus fixative type on karyometric measures.

The influence of fixation and embedding methods in seven urologic tumor samples was studied karyometrically for 12 preparatory techniques. Routine histologic formalin fixation was compared with Carbowax and Kryofix fixatives. Also, histologic material was studied embedded in paraffin and plastic (GMA) and secondarily in plastic (after paraffin embedding). From the cell suspensions, cytocentrifuge preparations were made (10 minutes, 1,500 rpm). The influence on nuclear light microscopic characteristics for two morphometric and five texture features in Feulgen-stained nuclei was evaluated. Nuclear features were influenced by both fixation and embedding method. The most extensive karyometric differences were found between different embedding techniques. More abnormally shaped tumor cell nuclei tended to occur with plastic (GMA) embedding methods. Plastic embedding proved to be superior to paraffin for all three fixation methods. Reembedding of archival formalin-fixed, paraffin-embedded material in plastic greatly influenced nuclear features, nuclear area in particular. We conclude that nuclear features are particularly influenced by the embedding method applied.

Cell Nucleus↗
PubMed1994

Microwave-antigen retrieval for proliferation analysis (MIB-1) and quanticyt karyometry of bladder washings.

Bladder washings can be used for simultaneous karyometry and proliferation analysis using MiB-1 as a proliferation marker. We analyzed 42 problem cases with a discordance between cytologic and karyometric classification (QUANTICYT), in which the karyometric classification was based on a combination of a nuclear shape parameter and DNA (2cDI). Moreover, 25 concordant cases were analyzed: 5 normal samples, 6 low-grade tumors and 7 high-grade tumors. All normal samples and all low-grade tumors had labelling indices below 10%, and all high-grade tumors over 10%. For the discordant low-grade tumors, the QUANTICYT classification correlated better with the MiB-1 labelling than the cytologic diagnosis. There was a clear correlation between 2cDI and MiB-1 labelling index. Slightly elevated MiB-1 labelling indices might have some prognostic value.

Antibodies, Monoclonal↗
PubMed1994

PAPNET for analysis of proliferating (MIB-1 positive) cell populations in cervical smears.

In diagnostic tumor pathology, immunohistochemical detection of proliferating cell populations is increasingly used. With the event of microwave-antigen retrieval it has become possible to detect proliferating cells in cervical smears staining positive for MiB-1. We report that with the PAPNET system, using neural network computing, it is possible to collect from the smears the images with epithelial fragments containing positive nuclei. We used this system for quantification of staining results. Cases with carcinoma in situ contained many epithelial fragments having a large number of positive-staining nuclei and with labelling indices of 60 +/- 16. Dysplasias were often completely devoid of cells with positive nuclei. In addition, we could not detect differences between progressive and regressive dysplasias. Automatic prescreening of immunostained smears using PAPNET is useful when it is desired to quantify staining results.

Antibodies, Monoclonal↗
PubMed1994

Nonchemical dehydration of fixed tissue combining microwaves and vacuum.

A novel histoprocessing method for paraffin and plastic sections is presented in which dehydration of fixed tissue blocks is achieved within 5 minutes by microwaving under vacuum. Exploiting the decrease in boiling temperature under vacuum, we succeed in evaporating liquid molecules in the tissues at physiological temperatures. In this microwave-vacuum dehydration method, the fixed tissue does not come in contact with ethyl alcohol. For the paraffin method, the nonchemically dehydrated tissue is directly placed in the intermedium isopropanol prior to embedding. For the resin method, it is directly placed in the monomer solution. With this method, microscopical imaging can be brought closer to the in-vivo situation as is illustrated in liver and kidney sections. In principle, this microwave-vacuum dehydration method can also be used for ultrastructural studies.

Animals↗
PubMed1993

Neural network processing can provide means to catch errors that slip through human screening of pap smears.

The problem of the false-negative smear deserves the attention of the cytologic community. We found that by using the PAPNET system, equipped with neural network programming, cancer cells can be detected in repeatedly misdiagnosed Pap smears. The correct diagnosis of these false-negative smears depended on the skills of the diagnostician to recognize the cells on one or more of the 128 tiles of the video display as abnormal, and to make the proper decision when to turn to light microscopy. In 8 of the 10 tested false-negative smears, the cancer cells were found exclusively in epithelial fragments; in two cases there were no more than five abnormal cells in the smear (which were detected by PAPNET). This study gave us insight into the nature of the false-negative problem and showed us that the application of neural network processing can provide means to catch errors that slip through human screening of Pap smears.

Clinical Competence↗
PubMed1993

PCNA independence of Ki-67 expression in HPV infection.

12 Infectious Wart lesions were stained using the streptavidin-biotin immunoperoxidase method for PCNA10, MIB-1 (Ki-67 equivalent antigen) and Human Papilloma Virus antigen to study the effect of HPV presence on epidermal proliferation. Using strict methods to avoid observer bias, Ki-67 antigen was found in a high proportion of nuclei in the suprabasal layers together with HPV antigens, in the absence of PCNA staining. This finding indicates that DNA synthesis related, Ki-67 antigen bearing structures can be raised in the human nucleus in the absence of induction of PCNA bearing structures, suggesting also structural independence between the antigen bearing molecules.

Antigens, Neoplasm↗
PubMed1993

A rapid ELISA for measurement of anti-glomerular basement membrane antibodies using microwaves.

The presence of anti-glomerular basement membrane antibodies is one of the features of Goodpasture's syndrome. Since the disease has a rapidly progressive course, an early diagnosis is essential. As was already demonstrated in other ELISA methods, 2.45-GHz microwave irradiation can accelerate all kinds of time consuming processes in several laboratory techniques. The application of microwaves in an ELISA for the measurement of anti-GBM antibodies in serum indicated that a considerable time reduction of 75% can be achieved, resulting in a rapid and reliable assay. In addition, microwaves can also have a positive effect on the resolution of that particular ELISA as shown in this study.

Anti-Glomerular Basement Membrane Disease↗
PubMed1993

Does microwave irradiation have other than thermal effects on glutaraldehyde crosslinking of collagen?

The effects of microwave irradiation (MWI) can theoretically be divided in thermal and non-thermal effects. Because there is still much debate on the contribution of non-thermal microwave effects, experiments were carried out in which the effects of isothermal microwave irradiation on glutaraldehyde (GA) crosslinking of native collagen membranes (NCM) is studied. A total of 20 strips of collagen membrane of porcine origin were isothermally irradiated in 300 ml of a 0.1 (w/w) GA solution, 10 strips at 4 degrees C, and 10 strips at 20 degrees C. A temperature controlled microwave oven (630W) was adapted to allow for simultaneous cooling of the fixation solution preventing the MWI to induce any measurable thermal effects. Any possible temperature variations were recorded employing continuous fiberoptic temperature measurement. Control experiments were carried out under the same (isothermal) fixation conditions, but without MWI. The crosslinking action of the GA was evaluated by determining the shrinkage temperature (Ts) of the collagen strips. No significant difference (p > 0.05) could be observed between the increase in (Ts) of the microwaved and the increase in Ts of the nonmicrowaved strips. The increase in Ts at 4 degrees C (c. 14 degrees C) was lower than that obtained at 20 degrees C (c. 16 degrees C). It was concluded that MWI induces no substantial nonthermal effect on enhancement of GA crosslinking of collagen at these temperatures.

Animals↗
PubMed1993

Microwave immunoincubations using coverplate units.

Recently, the Coverplate immunostaining method was introduced. This system allows easy handling of the slides and is suitable for immunoincubations for a variety of antigens at the same time on consecutive sections, without having to apply droplets of the individual primary antibodies on the sections. In this study, temperature rise inside the Coverplate units during microwave exposure is investigated. The most suitable conditions for microwave immunoincubations are determined. Immunoincubations with the Coverplate unit are conducted in the microwave oven and the results evaluated.

Humans↗
PubMed1992

A model for quantitative follow-up studies of cervical lesions.

A model for follow-up studies of cervical lesions is described in which the specimen were taken in a noninvasive way using Cytobrushes and in which automatic measurement of the abnormal nuclei in the sampled epithelial fragments was possible because 2-microns thin Feulgen-stained plastic sections were prepared. The planimetric parameters AREA, PERIMETER, FORM PE, and FORM ELL, and the densitometric parameters optical density (OD) and integrated optical density (IOD) were assessed. The mean total volume and the mean total DNA were calculated using stereological methods. The moderate dysplasias differed from the carcinoma in situs for all the densitometric parameters except for OD, and from the invasive carcinomas for IOD and 5cER. In the moderate-dysplasia group, there were three types of DNA histograms: a highly abnormal type resembling the histograms of the carcinoma group, a normal type, and an intermediate type. Changes in DNA histograms can be established during follow-up studies of dysplasias without having disturbed the lesion due to the efficient and elegant noninvasive sampling method that was not used in earlier quantitative studies.

Carcinoma in Situ↗
PubMed1992

Fine-needle cytology of an eccrine spiradenoma of the breast: diagnosis made by a holistic approach.

Eccrine spiradenoma is a rather rare adnexal tumor of the skin. When the clinical presentation is that of a breast neoplasm, diagnosis can be difficult. As cytology was a new procedure for this tumor, the approach of choice appeared to be a holistic one. The cytologic picture showed bland groups of uniformly sized cuboid cells with scant cytoplasm, round to ovoid nuclei, and inconspicuous nucleoli, while in the groups rosettelike structures could be discerned. Only by integrating the data of clinical history, inspection, palpation, reaction on breast puncture, and immunologic findings could the diagnosis be made.

Adenoma, Sweat Gland↗
PubMed1992

Karyometry in recurrent superficial transitional cell tumors of the bladder.

Transitional cell carcinoma of the bladder has a high recurrence rate after local treatment. Progression to a higher stage occurs in 10-30% of the recurrent tumors, and early detection of potentially progressive tumors is important. In the current study morphometric, densitometric, and chromatin textural features of nuclei of superficial bladder tumors (pTa-T1) were studied to determine the value of karyometric features in the prediction of tumor progression. Seventy-two histological samples from 36 patients, consisting of both the primary and the first recurrent superficial tumor, were analyzed. Patients were divided into two groups: those with tumor progression, defined as an increase in tumor stage or occurrence of metastatic disease, and those without. Discriminant analysis on four karyometric features resulted in correct prediction of prognosis of 78% and 97% in the primary and recurrent tumors, respectively (P < 0.001). Tumor grade and stage did not offer additional information concerning prognosis. Karyometric analysis of recurrent superficial transitional cell tumors can be useful in selecting patients who need a more aggressive therapy. However, tumor characteristics of recurrent tumors varied and continuous evaluation of the karyometric features is necessary for early detection of an increase in the malignant potential of the tumor.

Carcinoma, Transitional Cell↗
PubMed1992

Microwave irradiation and cross-linking of collagen.

In a multifactorial experiment, dermal sheep collagen was treated in diluted glutaraldehyde solutions, 70% ethyl alcohol, Cialit 1:5000, and distilled water for 1, 3 and 5 min, respectively, in combination with microwave irradiation at different temperature settings. The shrinkage temperature indicating the degree of cross-linking achieved was then determined. Treatment in 0.65% glutaraldehyde with microwave irradiation setting for 60 degrees C resulted in the maximum shrinkage temperature within 1 min, whilst at the lower setting of 50 degrees C, the maximum shrinkage temperature for both glutaraldehyde solutions is only reached after 5 min. Neither microwave irradiation by itself, Cialit or ethyl alcohol induce cross-linking of collagen fibres. These findings are relevant for implant studies.

Animals↗
PubMed1992

Using Kryofix as alternative for formalin results in more optimal and standardized immunostaining of paraffin sections.

Although used for over one century formalin has several disadvantages which Kryofix, an alternative fixative for paraffin blocks used in Leiden for 6 years, does not have. In this study the effects of Kryofix on tissue regarding immunohistochemistry are compared with those of buffered formalin. All markers studied showed enhanced staining in the Kryofix blocks after 4 hours of fixation, whilst in some cases the immunostaining of the formalin blocks was even negative. For all markers, the sera could be further diluted for the Kryofix sections, for some with as much as a factor 20, enhancing the cost-effectiveness of the method. We established that for formalin, the fixation time strongly influenced the results. For Kryofix there was no time factor: the immunostaining results of 1 hour fixation were identical to those after 3 months of fixation. This study shows that by this method of fixation, in which there is no cross-linking of proteins, immunostaining of paraffin sections is optimized and standardized.

Ethanol↗