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Biomedical subjects

M E Boon

Publications and source records attributed to M E Boon.

At least 91 records · Page 5Linked to original sources
PubMed1992

Prediction of various grades of cervical neoplasia on plastic-embedded cytobrush samples. Discriminant analysis with qualitative and quantitative predictors.

The purpose of this study was to investigate whether discrimination into five groups of various grades of cervical preneoplasia and neoplasia is possible using discriminant analysis models. Data were analyzed for 242 cases diagnosed as either slight dysplasia (n = 50), moderate dysplasia (n = 50), severe dysplasia (n = 50), carcinoma in situ (n = 50) or invasive carcinoma (n = 42) and consisted of qualitative and quantitative features of cells derived from a repeat sample taken from the ectocervix as well as the endocervix using Cytobrushes. The samples were embedded in plastic, and thin sections were prepared, resulting in a monolayer of cut nuclei. The percentages of expected correct prediction were obtained by using 10,000 double cross-validation samples; the mean percentage of correct prediction into five groups using cross-validation was 65% (in the original analysis, 72%) and into two groups (dysplasia versus carcinoma in situ and invasive carcinoma) was 91% (93%). The results reflect group discrimination potential; we do not claim reliability of prediction for an individual patient. The patients were not a representative sample of the population; to investigate whether groups of patients could be discriminated on the basis of both qualitative and quantitative features, the data analyzed contain an almost equal number of observations in each of the five groups. The results indicate that features do not classify the cases in the same way; the discriminant analyses suggest that quantitative features play an important role in the discrimination of dysplasia from carcinoma cases, while the majority of the qualitative features are important in discrimination within the three dysplasia groups.

Biopsy↗
PubMed1991

ELISA incubation times can be reduced by 2.45-GHz microwaves.

The ELISA (Enzyme Linked Immuno Sorbent Assay) technique is widely applied in the field of immunology. The use of this technique implies several incubation periods, often requiring more than one hour each. Microwave irradiation is known to be very useful in accelerating different kinds of processes. This knowledge has led to the present study in which it is proved that 2.45-GHz microwaves are able to reduce ELISA incubation times. This time reduction of 50% or more concerns each of the four incubation steps of the specific indirect ELISA which is used to determine the amount of antibodies in NF90-hybridoma cell culture supernatants. These incubation steps involve the coating of the microtiter plate, the incubation with BSA against non-specific binding, and the incubations with the first and second antibody. Combinations of more microwave-influenced steps in one ELISA save a considerable amount of time. When in addition air is blown through the incubation fluid during microwaving, the extinction values are almost the same as those of conventionally performed ELISAs. Thus, a good match of power setting and irradiation time results in a total incubation time reduction from 5.5 hours to 2 hours in this particular ELISA. Carefully monitoring the temperature of the incubation fluids during irradiation with the use of a fiberoptic thermometer appeared to be of crucial importance in the development of an optimal procedure.

Enzyme-Linked Immunosorbent Assay↗
PubMed1991

Formalin is deleterious to cytoskeleton proteins: do we need to replace it by formalin-free Kryofix?

Formalin is hazardous for the environment and for the laboratory personnel and deleterious to cytoskeleton proteins. The pathology and anatomy laboratory can be formalin-free when Kryofix is used as a substitute fixative. In four years experience with Kryofix, we learned that immunostaining on paraffin sections is reproducible and of excellent quality. The current study concerns the comparison of interfilament staining on paraffin sections made from formalin or from Kryofix-treated tumors. For both keratin and vimentin there were false-negative findings in the formalin-fixed tumors. Of these two, vimentin was het most susceptible to formalin fixation. Three of the ten adenocarcinomas were positive for both keratin and vimentin, indicating that this double staining pattern is not uncommon. Postfixation of Kryofix-treated tissue with formalin results in false-negative immunostaining.

Adenocarcinoma↗
PubMed1991

Morphometry, densitometry and pattern analysis of plastic-embedded histologic material from urothelial cell carcinoma of the bladder.

An image analysis method of grading histologic sections of bladder carcinoma was tested. The method was new in four respects. First, for fixation of the biopsies a coagulant fixative was used. Second, 2-microns plastic sections were used to ensure the reproducibility of nuclear imaging. Third, a new stereologic approach was used for calculation of the nuclear volume and DNA content. Fourth, for the classification rule the morphometric, densitometric and texture features were used in concert. The IBAS 2000 instrument was used for the measurements. Texture analysis of the chromatin patterns was performed using Markovian texture features. Using discriminant analysis, of 22 parameters, 2 morphometric, 2 densitometric and 3 texture features were selected for the classification rule. With them, 89% of the bladder carcinomas were correctly classified into the three grades. All grade III tumors were classified correctly. Among the features tested, the densitometry of the DNA had the highest F values. All of the grade III tumors and 45% of the grade II tumor group had DNA histograms indicating aneuploidy. This study showed that plastic-embedded material is well suited to morphometry and densitometry and can be used for quantitative grading of bladder carcinoma.

Carcinoma, Transitional Cell↗
PubMed1990

[Malignant melanoma in a primary care pathologico-anatomical laboratory in 1988 and the freckle bus year].

Our laboratory is specialized in pathology and cytology service to general practitioners (GPs). In 1988 we received approx. 1600 skin biopsies from GPs, two were melanomas. In 1989, when some 3200 biopsies were examined, the number of melanomas increased to 15. In that year a screening service was provided in the summer months using a 'freckle bus'. Only one melanoma patient was sent to the GP for further investigation through this screening service. We presume that the concomitant publicity in the mass media was more important for melanoma detection. The characteristics of the 17 melanomas detected by the GPs were in accordance with published epidemiological data. They were, however, very small with a median diameter of 5 mm. More than 70% of the melanomas had a thickness less than 1 mm. The task of the GP in detecting melanomas is discussed. In our study the GPs act in accordance with the proposed guidelines: they only excise lesions with a low suspicion, the margin being at least 1 mm and all biopsies are verified histologically.

Adult↗
PubMed1990

[Results of the Leiden mass screening for cervix uteri carcinoma; the 'young' (24-34 years) versus the 'old' (35-54 years) group of women].

The population screening for cervical carcinoma in the Leiden region took place in the period 1977-1988. It involved four screenings of women in the age group 35-54 years, and two screenings of women in the age group 25-34 years, with a screening interval of 3 years. We conclude that screening for cervical carcinoma is useful. Cytological investigation of young women (under 35 years) is indicated. This conclusion is based in part on the data of the regional and national cancer registries and on the mortality figures in The Netherlands. Data on HPV infection in Dutch males and females were also taken into account.

Adult↗
PubMed1990

The reproducibility of cytomorphometrical grading of bladder tumours.

The reproducibility of cytomorphometrical nuclear area measurements on transitional cell carcinoma is studied. The inter-individual consistency is low (r = 0.55, P = 0.0005) when nuclei for measurement are chosen at random. When we use a systematic analysis based on cell situation and cytological features of malignancy to select the 50 nuclei for measurement per slide, the consistency between two technicians appears to be significantly higher (r = 0.90, P = 0.015). Not only interindividual consistency increases using the selection, but the correlation with histological tumour grade also improves significantly for both technicians. The results show that cytomorphometry is a method of grading bladder carcinoma when an accurate selection of nuclei to measure is used. Cytomorphometrical studies should contain a clear description of the way the nuclei for measurement are chosen.

Humans↗
PubMed1990

Immunocytochemistry on free-floating sections of rat brain using microwave irradiation during the incubation in the primary antiserum: light and electron microscopy.

We studied the effects of microwave irradiation during the incubation of free-floating brain sections with primary antibodies against gamma-aminobutyric acid (GABA), enkephalin and vasopressin. Vibratome sections of perfusion-fixed rat brain were incubated: (a) overnight at room temperature (20-22 degrees C), (b) during various periods of time under microwave irradiation, such that the induced temperatures did not exceed 10 degrees C, (c) same as (b) but with induced temperatures not exceeding 40 degrees C, (d) without microwave irradiation, at 4-10 degrees C (temperature control for (b)), (e) same as (d) but at 40 degrees C (temperature control for (c)). During the incubation-irradiation we continuously monitored the temperature and controlled it by cooling and by manipulating the energy output of the magnetron. The peroxidase immunocytochemical procedure was completed using for all sections the same incubation parameters. Selected GABA-immunoreacted sections were examined in the electron microscope. Incubation at 10 degrees C in the primary antiserum as short as 30 min, with or without microwave irradiation, already results in (weak) binding of the antibodies to immunoreactive structures. One or 2 h of incubation in the primary antiserum in the microwave oven at 40 degrees C or at the same temperature outside the microwave oven results in excellent staining of GABA-immunoreactive structures and of good staining of enkephalin- or vasopressin-immunoreactive structures. The ultrastructural details were much better preserved in incubated-irradiated sections than in sections incubated overnight and only slightly less preserved than in the other control sections. There is no improved penetration of the antibodies into the sections. We conclude that by using microwave technology or by raising the temperature of the incubation medium, the time of incubation, at least in these antisera, can be shortened drastically, whereas the ultrastructural details remain well preserved.

Animals↗
PubMed1990

Effect of regular 3-yearly screening on the incidence of cervical smears: the Leiden experience.

The effect of regular 3-yearly screening over a period of 12 years, on the incidence of cervical cancer in 25,000 women aged 35-54 years, is examined. The rate of squamous cell carcinoma decreased from 0.38 per 1000 women in the first round to zero in the fourth round. Similarly, the rate of carcinoma in situ declined from 1.69 per 1000 women in the first round to 0.35 per 1000 in the fourth round. The rates of severe dysplasia showed no decline. Cytologic under diagnosis of carcinoma-in-situ and cervical carcinoma increased with each round. Widowed and divorced women and those living in urban areas were identified as high risk groups.

Adenocarcinoma↗
PubMed1990

Microwaves for microscopy.

Sample preparation for microscopy is based on physical and chemical processes. These processes can be influenced by microwave irradiation. The prerequisite for the development of good microwave procedures is knowledge of histochemistry combined with understanding of the physics of microwave irradiation. Examples of superior results of fixation, processing, and (immuno) staining performed in the microwave oven are presented, both for light- and electron microscopy.

Animals↗
PubMed1990

Microwave-stimulated brain enzyme incubations are possible at the unphysiological condition of 50 degrees C.

Microwave-stimulated enzyme incubations for acetylcholinesterase, 5'-nucleotidase, alkaline phosphatase, lactate dehydrogenase, malate dehydrogenase, succinic dehydrogenase and isocitric dehydrogenase were studied, and compared with incubations in a waterbath. Temperature settings of 37 degrees C and 50 degrees C were used, and the incubation times were varied from 30 seconds to 30 minutes. The desired temperature of the incubation solution was reached in the microwave oven within 1 minute, whilst in the waterbath it took 10 to 25 minutes. The microscopic results for alkaline phosphatase and succinic dehydrogenase at a temperature setting of 50 degrees C were superior in the microwave method for incubation times less than 15 minutes. It is postulated that the increased reaction product of alkaline phosphatase and succinic dehydrogenase is due to a temperature effect, which has to be large enough to be of practical value. For the other enzymes studied, microwave-stimulated incubations were no better than the conventional incubations at corresponding temperatures. For 5'-nucleotidase there were aspecific lead deposits in the microwave method. All enzymes performed at the elevated, unphysiological temperature of 50 degrees C proved to have advantages, except for 5'-nucleotidase, whilst for malate dehydrogenase there was an aspecific reduction of the colour developer at this temperature.

Animals↗
PubMed1989

Human papillomavirus (HPV)-associated male and female genital carcinomas in a Hindu population. The male as vector and victim.

Epidemiologic, histologic and immunohistochemical data concerning male (penile) and female (cervical and vulvar/vaginal) genital carcinomas in a Hindu population are reported. The data are from Bali, an Indonesian Hindu island in a country with a predominantly Muslim population. In contrast to the surrounding Muslim population, circumcision is rare in the people of Bali, and the rate of phimosis in grown men is very high. The Balinese epidemiologic data of 1985 to 1986 were compared with 1986 data from The Netherlands. In Bali, cervical carcinoma was the most frequent carcinoma in women, and vulvar/vaginal carcinoma ranked seven. These carcinomas were much less frequent in The Netherlands. In Balinese men, penile carcinoma is the second most frequent carcinoma, whereas it is rarely diagnosed in The Netherlands. Penile carcinomas are found in Bali in younger age groups than in The Netherlands. Based on the immunohistochemical staining results, it is estimated that over 75% of the studied Balinese genital carcinomas contain human papillomavirus (HPV). The data presented in this paper may indicate that the cofactor of impeded postcoital hygiene can be of great importance for male and female HPV-associated genital carcinogenesis. It is clear that Balinese men, in particular men with extreme phimosis, are both vectors and victims of HPV. In The Netherlands the man is exclusively the vector of HPV.

Adult↗
PubMed1989

Microwave treatment of xenogeneic cartilage transplants.

Human rib cartilage was irradiated with microwaves according to six different methods and transplanted into rabbits. Untreated rib cartilage preserved in Cialit served as a control. After 12 and 40 wk of implantation, the microscopic appearance of these xenogeneic cartilage transplants was given a score in comparison with the transplants preserved in Cialit. The microwave treatment of the cartilage appeared to improve the results. The Cialit-preserved transplants showed progressive resorption by macrophages with central necrosis and fragmentation, which was not present in the microwave-treated grafts. Microwaves seem to stabilize the cartilage matrix and enhance the diffusion of fixatives. Irradiation in ethanol as an immersion fluid appeared to be the best method. The results of transplantation can benefit from the use of microwaves in the preservation of the cartilage. It is argued that, in addition, microwave irradiation might be used for inactivation of human immunodeficiency virus in human cartilage used for transplantation.

Animals↗
PubMed1989

Accelerated immunogold silver and immunoperoxidase staining of paraffin sections with the use of microwave irradiation. Factors influencing results.

With the use of microwave irradiation, incubation times for the immunotechniques used in immunomicroscopy can be shortened significantly. The authors found that factors influencing results are irradiation time, power output, and presence of gold label. Precise temperature control is essential, and techniques to achieve this are discussed. For beta-human chorionic gonadotropin (beta-HCG), the results with the immunoperoxidase technique were inferior to those of the conventional technique, and with the immunogold silver technique an enhancement of labeling results was achieved. Immunogold silver staining for beta-HCG on paraffin sections can be performed with the use of microwave irradiation within one hour.

Histological Techniques↗