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Biomedical subjects

M E Boon

Publications and source records attributed to M E Boon.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cell replication rates and processes concerning antibody production in vitro are not influenced by 2.45-GHz microwaves at physiologically normal temperatures.

Several contradictory papers concerning the effects of microwaves on living organisms and on in vitro cell suspensions have been published through the years. These papers are difficult to interpret, because temperature measurement data are often lacking. Reliable temperature measurements are important, because they enable one to determine whether the observed microwave effects are thermal or nonthermal. Therefore, a method was developed to investigate microwave effects on cellular processes, in which the temperature was precisely monitored during microwave treatment using a fiberoptic thermometer. This method involved the processes required for in vitro production of monoclonal antibodies. Monoclonal antibodies are vital ingredients in (microwave-stimulated) immunostaining techniques and ELISAs, which have become important techniques in neuroscience. The effects of 2.45-GHz microwaves on mouse myeloma and (neural) hybridoma cell replication rates and on antibody production were investigated. In addition, the effects on the cell fusion abilities of spleen lymphocytes and myeloma cells and on in vitro immunization were studied. The results of this study show no effects of microwaves on either of the processes mentioned using exposure times up to 5 h a day at a physiologically normal temperature of 37 degrees C. It was concluded that the effects of 2.45-GHz microwaves detected at higher temperatures are thermal effects and that no indications for nonthermal 2.45-GHz microwave effects exist under the exposure conditions used in the present study.

Animals↗
PubMed1998

Visualization of vaginal flora in cervical smears using a modified microwave silver-staining method.

The advantage of studying the vaginal flora to determine the bacteria and fungi present in cervical smears (as opposed to cultivation of these micro-organisms) is that the micro-organisms can be observed in their natural habitat. However, they are only faintly stained by the conventional Papanicolaou method. Accordingly, contrast is weak and visualization poor. For this reason, we developed a modified microwave silver-staining method that can be performed retrospectively on stained smears. Bacteria and fungi stain distinctly black and can be studied in greater detail, and their inter-relationship can be visualized. Haematoxylin or Eosin counterstain allows us to visualize vaginal inhabitants in relation to epithelial cells. In the series presented here, we show that a modified microwave silver-staining method is well suited to studying the ecology of micro-organisms in smears taken from women presenting to their doctor with clinical symptoms. Using this staining method, we have shown that lactobacilli overgrowth is associated with symptoms.

Actinomyces↗
PubMed1997

Rapid microwave-stimulated fixation of entire prostatectomy specimens. Biomed-II MPC Study Group.

Conventional fixation of large solid surgical specimens is a slow process. Consequently, autolytic damage to tissues may occur if the fixative does not reach the central part of the specimen in time. However, as there is also a time relationship between formalin fixation and antigen masking, fixation for too long can also be detrimental. In seeking the optimum balance for fixation, microwave irradiation might be of assistance. This study set out to evaluate methods for fixing entire prostate glands within a brief period of time, using microwave-stimulated formalin fixation. The results show that entire prostates can be optimally fixed if formalin is present throughout the tissue as the temperature is increased by microwave irradiation. This is achieved by injecting the fixative into the prostate at multiple sites immediately following prostatectomy. The technique described ensures standardization of a critical step during tissue processing, leading to uniform microscopic results with both routine and immunohistochemical stains. It is a simple, rapid method, suitable for routine diagnostic use. Using this modified approach, DNA of much larger sizes can be extracted from paraffin-embedded material, which could expand the possibilities for molecular analysis.

Cadherins↗
PubMed1997

Seasonal fluctuations in the cervical smear detection rates for (pre)malignant changes and for infections.

The detection of diseases can exhibit seasonal fluctuations. This can be studied in cervical smears. Over a 9-year observation span (January 1983-January 1992) a series of 504,093 cervical smears obtained from a routine cytology laboratory in The Netherlands were examined for infections (monilia, trichomonas, actinomyces, human papilloma virus [HPV], chlamydia, and herpes) as well as for mild, moderate, and severe dysplasias, carcinoma in situ, and squamous carcinoma. Statistical analysis (principal component analysis) demonstrates clear seasonal rhythms in the detection of infections as well as in precursor lesions. These findings suggest that we are dealing with "true" detection rhythms. For the detection of (pre)malignancy and HPV, yearly fluctuations in women being screened might be the explanation for our observations.

Actinomycosis↗
PubMed1997

Confocal laser scanning microscopy of porcine skin: implications for human wound healing studies.

The structure of porcine skin as examined by light microscopy is reviewed and its similarities to and differences from human skin are highlighted. Special imaging techniques and staining procedures are described and their use in gathering morphological information in porcine skin is discussed. Confocal laser scanning microscopy (CLSM) was employed to examine the structure of porcine skin and the findings are presented as an adjunct to the information already available in the literature. It is concluded that CLSM provides valuable additional morphological information to material examined by conventional microscopy and is useful for wound healing studies in the porcine model.

Animals↗
PubMed1997

Sporicidal activity of chemical and physical tissue fixation methods.

AIMS: The effects of alcohol based fixation and microwave stimulated alcohol fixation were investigated on spores of Bacillus stearothermophilus and Bacillus subtilis (var. niger). METHODS: Spores were exposed to 10% formalin, or different concentrations of various alcohol containing fixatives (Kryofix/Spuitfix). Adequate controls were also set up in conjunction with the test solutions. The spores were immersed with and without adjunctive microwave stimulation in the various solutions tested. Possible surviving spores were recovered in revival broth and after incubation, and Gram staining viable counts were performed. RESULTS: Alcohol based fixatives did not have a sporicidal effect on B stearothermophilus or B subtilis (var. niger) spores, and microwave stimulated alcohol fixation at 450 W and up to 75 degrees C did not have a sporicidal effect. CONCLUSIONS: When alcohol based fixatives are used for fixation, precautions should be taken with the material thus treated, as it may contain viable spores or other pathogens, which are destroyed after 24 hours of formalin treatment. Of the physicochemical methods tested involving microwaving, none was successful in eliminating viable spores from the test material.

Bacillus↗
PubMed1997

Conventional bladder wash cytology performed by four experts versus quantitative image analysis.

Bladder wash cytology provides superior results for the detection of bladder malignancies than does voided urine analysis. Image analysis systems have been developed for quantification of cytologic features. In this study, routine bladder wash cytology is compared with an automated image analysis system (QUANTICYT). We studied a random set of 100 bladder wash samples from a population of 1614 patients in follow-up after bladder cancer. Four experienced pathologists interpreted the same 100 Papanicolaou-stained slides. Cytologic and image analysis results were compared for prediction of a cystoscopic lesion, histologic abnormalities, and tumor recurrence. After application of receiver operating characteristic curves, prediction of a cystoscopic lesion by cytology and image analysis was comparable. Both the image analysis system and the cytologic examination detected all of the high-grade lesions. Image analysis was superior to cytologic analysis for the prediction of tumor recurrence after normal findings at cystoscopic examination.

Cell Nucleus↗
PubMed1996

Consequences of neural network technology for cervical screening: increase in diagnostic consistency and positive scores.

BACKGROUND: Screening programs for the early detection of cervical carcinoma are criticized because of the problem of false-negative diagnoses. A successful approach for solving this problem is applying neural network technology (PAP-NET) to assist the cytotechnologist (CT) in finding the (few) abnormal cells in the smear. METHODS: In 3 consecutive years (1992, 1993, and 1994), 25,767 smears were screened conventionally and 65,527 with the aid of PAPNET by 7 CTs. For each CT, the scores for atypias of undetermined significance, squamous or glandular (ASCUC/AGUS according to the Bethesda classification system), indicated by Positive 1, for low grade precursor lesions, by Positive II, for high grade lesions and invasive carcinoma, by Positive III, were calculated for both screening methods. The histologic scores were also calculated. RESULTS: The mean positive scores of the seven CTs were higher for PAPNET than for conventional screening, and the coefficients of variability were lower. For Positive III smears, the consistency in screening was significantly higher for PAPNET than for conventional screening. The higher histologically positive scores for carcinoma in situ and invasive carcinoma indicated an increased screening sensitivity. CONCLUSIONS: As demonstrated by the improvement in the performances of all CTs involved, screening efficacy was enhanced by the use of neural network technology.

Adult↗
PubMed1996

Upgrading unsatisfactory cervical smears with the MiB-1 method.

When an unsatisfactory smear (thick inflammatory infiltrate or blood influencing the staining characteristics of the epithelial cells) is restained for MiB-1, the diagnostic proliferating cells are visualized, and the MiB-1-positive smears can be thus upgraded as borderline, grade I, II, and III, corresponding with the cytologic diagnoses of, respectively, ASCUS, CIN I, II, and > or = III. In a period of 18 months, 2,068 unsatisfactory smears out of a material of 84,817 smears were restained for MiB-1. In the unsatisfactory group, significantly more abnormal smears were detected than in the satisfactory group. Seventy-five of the unsatisfactory group were biopsied because of the MiB-1 findings: Three women proved to have severe dysplasia, four had carcinoma in situ, and three had invasive carcinoma. The per mileage for invasive cervical carcinoma was ten times larger in the unsatisfactory group than in the satisfactory group; thus the MiB-1 method has further enhanced our diagnostic acumen in this difficult type of smears.

Antigens, Nuclear↗
PubMed1996

Calcification of cross-linked collagen-elastin membrane implants in vivo and their proposed use in bone regeneration.

Factors influencing the in vivo calcification of porcine collagen membranes containing elastic fibres were investigated by light and confocal microscopy. Two glutaraldehyde (GA) cross-linking protocols were used: a new one involving microwaving (NEWGA), and a conventional method using GA treatment at room temperature (OLDGA). We observed that the physical and chemical properties of implanted membranes will influence the acute inflammatory response, which initially checks the calcification process. The NEWGA membranes are superior in cases where rapid calcification is desired. In this context, it is proposed that NEWGA membranes may serve as a useful delivery system for bone morphogenetic protein (BMP).

Animals↗
PubMed1996

Quanticyt: karyometric analysis of bladder washing for patients with superficial bladder cancer.

OBJECTIVES: Quantitative cytology by image-analysis techniques enables objective interpretation of nuclear features in light microscopic images. QUANTICYT, a quantitative karyometric cytology system, was used in the follow-up of patients with superficial bladder cancer. METHODS: From 1992 to 1995, 4137 samples from 1412 patients were obtained. At 1-year follow-up after the initial bladder washing, a tumor recurrence rate of 21% was found. In this period, tumor progression to invasive disease occurred in 1.6% of patients. Scoring of tumor by the QUANTICYT system was based on two nuclear features: the 2c deviation index and the mean of a nuclear shape feature: MPASS. RESULTS: The method was found to be reproducible and superior to visual cytologic interpretation. QUANTICYT analysis of the bladder washings resulted in a score of low, intermediate, and high risk. In a multivariate analysis, highest grade of earlier tumor and QUANTICYT risk score were the best predictors of tumor recurrence and progression. For the easy application of QUANTICYT analysis in daily routine, a report form that included patient history and DNA histogram was developed. CONCLUSIONS: QUANTICYT karyometric analysis of bladder-wash material proved a useful, clinically applicable grading tool in the follow-up of patients with superficial bladder cancer, with sufficient power to be used in decision-making in the individual patient.

Administration, Intravesical↗
PubMed1996

4D confocal microscopy for visualisation of bone remodelling.

Until recently it was very time consuming and difficult to make three-dimensional (3D) images of newly formed bone. With the advent of confocal technologies and increased computer power, 3D imaging is greatly facilitated. In this paper we demonstrate that enhanced confocal visualisation of newly formed bone is possible when bone is labelled in vivo sequentially with two osteotropic markers (xylenol orange and tetracycline). Computer-assisted reconstruction of the confocal optical sections was achieved through the use of the CONVEX Application Visualisation System (AVS). The computerised image data provides the researcher with ample flexibility in displaying the results. It was found that CSLM combined with AVS is excellent for visualising the remodelling process in three and four dimensions, in which the fourth dimension is time. With this approach visualised bone remodelling has become possible in a manner not easily achieved by other techniques.

Animals↗
PubMed1996

Lessons from the experimental stage of the two-step vacuum-microwave method for histoprocessing.

The two-step vacuum-microwave method simplifies and shortens histoprocessing. Acting margins are small so that fine-tuning is required. Temperature, vacuum and time should be in perfect balance. If not, a "cooking" effect (too high temperature) can easily be detected in the epidermis of skin biopsies. An adverse vacuum effect (when vacuum is obtained too abruptly) produces clefts, first observed where different tissues are contiguous. When time is set too shortly, impregnation will be insufficient, which is best seen in kidney tissue. The lessons from these observations may help future users to be troubleshooters while installing their unit.

Biopsy↗
PubMed1996

Microwave-antigen retrieval: the importance of pH of the retrieval solution for MIB-1 staining.

Using microwaves for microscopy almost invariably implies working at elevated temperatures. In microwave studies it became evident that high temperatures do not inevitably damage the tissues. On the contrary very high temperatures can even be beneficial. The most striking example is the 'heat shock' of formalin-fixed paraffin sections in the microwave oven with temperatures higher than 100 degrees C, revealing otherwise hidden epitopes. These microwave applications have triggered a breakthrough in pathology. The pH of the microwave-retrieval solution is decisive for the staining results, particularly for MiB-1. There is no staining of proliferating cells between pH 3.5 and 5.0. Between pH 5.0 and 6.5 we observed an increase in the number of MiB-1-positive stained nuclei. Our findings indicate that in quantitative work it is of extreme importance to standardise the pH of the retrieval solution and to choose pH 6.5 for optimal results.

Antibodies, Monoclonal↗
PubMed1996

The cervico-vaginal epithelium during 20 cycles' use of a combined contraceptive vaginal ring.

The aim of the study was to evaluate the influence of a combined contraceptive vaginal ring (CCVR) made of Silastic on the cervico-vaginal epithelium during 20 cycles of use. A total of 76 volunteers used the CCVR releasing 0.120 mg etonogestrel and 0.015 mg ethinyloestradiol daily. Cytological samples were taken of the vaginal epithelium, the ectocervix and the endocervix before the start, at 4 and 12 months, and at the end of the study. Cytology, hormonal profiles, human papilloma virus (HPV) status, DNA-flow cytometry, bacterial flora, and morphometry was performed on these samples. Colposcopy and histopathology of biopsy specimens were performed at the end. No cytological changes of the squamous epithelium or the columnar epithelium were found. HPV was detected in three samples of three different women. At least two of them reverted to HPV negative during the rest of the study period. Aneuploidy was diagnosed in 11 women before the study. Seven of them changed to diploid during the study. No changes from diploid to aneuploid were seen. Aneuploidy was not seen in any of the HPV positive samples. Although bacterial flora showed considerable variation during the study, no significant influence of the CCVR could be established. Morphometrical analysis showed an increasing nucleus:cytoplasm ratio of the squamous cells during the study. Mild dysplasia was detected in one woman at the end of the study. It was concluded that no unfavourable cytological or bacteriological changes of the cervico-vaginal epithelium were demonstrated during 20 cycles of CCVR use. The vaginal epithelium became more progestogenic during the study.

Aneuploidy↗
PubMed1996

Evidence for dissociation of histone mRNA expression from cellular proliferation in cutaneous human papillomavirus infection.

Replication of human papillomavirus (HPV) is thought to require the expression of components of the host cell DNA replication apparatus. The expression of the mRNA encoding the DNA replication-dependent histones H2B, H3, and H4 was investigated in a series of verrucae using an FITC-labelled oligonucleotide cocktail for in situ hybridization, to explore the possibility of HPV inducing the transcription of host cell histones. In contrast to normal epidermis, in which the majority of histone mRNA labelling was confined to basal cells, a bimodal distribution of histone positivity was observed in all verrucae. In addition to basal hyperproliferation-associated labelling, numerous positive suprabasal cells were found within the stratum spinosum. By contrast, in another hyperproliferative lesion, psoriasis, the labelling pattern was similar to that found in the normal controls, with characteristic basal hyperproliferation but no evidence of suprabasal labelling. The presence of HPV replication in every verruca and its absence from all controls of normal and psoriatic skin were demonstrated immunohistochemically, using a polyclonal antibody to the viral capsid proteins. It is proposed that the presence of histone mRNAs in differentiated suprabasal keratinocytes of verrucae is due to the virus turning on parts of the cellular apparatus in order for it to replicate in the absence of cellular proliferation. The results also emphasize that when assessing proliferation with in situ hybridization for histone mRNA, the possibility of HPV causing the labelling of non-proliferating cells should be considered.

Adolescent↗
PubMed1995

Confocal microscopy of false-negative breast aspirates.

Even when using a novel optimized FNA-21 for breast fine-needle aspiration biopsy, our series of 163 breast lesions with consecutive histology, including 110 carcinomas, contained eight cancer cases with a negative cytologic diagnosis. Two consisted exclusively of thick, undiagnosable epithelial fragments and were devoid of detached malignant cells on which the proper diagnosis could have been made. Optical sectioning of the original smears by the confocal microscope allowed us to reclaim from these epithelial fragments the diagnostic abnormal chromatin patterns, even in the air-dried smears. In the thin optical sections the cancerous tubular or cribriform growing pattern was visualized. The high spatial resolution of the confocal microscope can be further exploited with the application visualization system (AVS). The AVS three-dimensional reconstructions allow us to see the surface of these malignant cells in a detail approaching that of scanning electron microscopy. Furthermore, the internal aspects of the malignant nuclei can be visualized with these techniques.

Biopsy, Needle↗