Biomedical subjects

Lambrecht P Kok

Publications and source records attributed to Lambrecht P Kok.

8 recordsLinked to original sources

PubMed2006

Dysbacteriosis in silver-stained cervical smears of Dutch-Moroccan immigrants: HPV infection and preneoplasia.

The vaginal/cervical smears of a group of Moroccan immigrants were used to compare vaginal dysbacteriosis (i.e., a bacterial population change with a decrease in lactobacilli and an increase of coccoid bacteria in vaginal/cervical smears) with Dutch women. From our archives, 779 smears from Moroccan immigrants were compared with 1,060 smears of age-matched Dutch women. For bacterial flora, Jones-Marres silver stains were used to define four groups. Koilocytosis and cervical intraepithelial neoplasia (CIN) were also recorded. The bacterial vaginal flora of Moroccan immigrants and Dutch women was different. The Moroccan women had a lower dysbacteriosis than Dutch women (3% vs. 24%). Koilocytosis and CIN were less frequent in the immigrant population. The possible synergy of a disturbed vaginal flora with human papillomavirus (HPV), HIV, or cervical preneoplasia indicates that vaginal hygiene and a normal flora may have positive effects on the uterine cervix.

Case-Control Studies↗

PubMed2006

Optimized quality of histologic images allows the use of neural network scanning in diagnosis of fungal infection of abnormal nails.

OBJECTIVE: The neural network scanning (NNS) system, formerly known as Papnet, is capable of selecting fungi in cervical smears. The objective of this study was to investigate whether the optimized quality of histologic images created using a combination of coagulant fixation and microwave histoprocessing allows the application of this computer-assisted microscopy in the diagnostic process. STUDY DESIGN: In a prospective study, 117 abnormal nails clinically suspect for fungal disease werefixed in a coagulant fixative, BoonFix, processed in a microwave histoprocessor to obtain optimal paraffin sections and stained with the periodic acid-Schiff (PAS) method. The stained paraffin sections were randomly numbered and screened by two independent pathologists for diagnosis of fungal hyphae and spores. The same sections were subsequently scanned by a neural network, and a maximum of 128 digital images produced by the system were screened and diagnosed by pathologists. Using light microscopy as the gold standard for diagnosis of fungi, the usefulness of NNS was then assessed. RESULTS: The fungi and spores were clearly demonstrated in the paraffin sections, and the NNS system detected and recorded them efficiently. The hyphae and spores could be identified in these pixilated images with relative ease. Of the 117 examined cases, 50 were positive and 47 negative by both methods. In the 20 remaining cases, NNS did not present images of fungi that were present in the histologic sections. In practice, this implies that only 67 out of 117 cases (57%) must be screened by light microscopy. NNS recorded not only fungi and spores in the 128 digital images but also artifacts, such as round, deeply PAS-positive granules of talcum powder, which by light microscopy might be mistaken for fungal spores. CONCLUSION: NNS proves applicable for the selection of spores and fungi if the histologic sections are of sufficiently high quality. As a result, the number of slides to be screened by light microscopy can be reduced substantially. In a throughput diagnostic laboratory handling a large number of such cases this technology can be highly valuable.

Adolescent↗

PubMed2005

Human papillomavirus testing as a cytology gold standard: comparing Surinam with the Netherlands.

Polymerase chain reaction to detect high-risk human papillomavirus has been suggested as a gold standard for cytology. The Netherlands and Surinam were prospectively compared in regard to the proportions of Negative, Atypical Squamous Cells of Undetermined Significance, and Squamous Intraepithelial Lesion smears that had detectable high-risk human papillomavirus. For the Netherlands, 14 600 negative, 270 Atypical Squamous Cells of Undetermined Significance and 120 Squamous Intraepithelial Lesion smears were evaluated by polymerase chain reaction. For Surinam, 150 negative, 50 Atypical Squamous Cells of Undetermined Significance, and 150 Squamous Intraepithelial Lesion smears were evaluated by polymerase chain reaction. In all, 4% of Dutch and 80% of Surinamese negative smears had detectable high-risk human papillomavirus (chi2=1313, P<0.00001). In total, 41.9% of Dutch and 84% of Surinamese Atypical Squamous Cells of Undetermined Significance smears had detectable high-risk human papillomavirus (chi2=28, P<0.00001). Totally, 67.5% of Dutch and 94% of Surinamese SIL smears had detectable high-risk human papillomavirus (chi2=30, P<0.00001). The Negative: Atypical Squamous Cells of Undetermined Significance odds ratio was 0.058 for the Netherlands and 0.762 for Surinam (chi2homog=31, P<0.00001). The Negative: Squamous Intraepithelial Lesion odds ratio was 0.020 for the Netherlands and 0.255 for Surinam (chi2homog=31, P<0.00001). The Atypical Squamous Cells of Undetermined Significance: Squamous Intraepithelial Lesion odds ratio was 0.347 for the Netherlands and 0.335 for Surinam (chi2homog=0.005, P>0.75). Human papillomavirus DNA testing may not be a suitable gold standard in general because its use would make specificity and sensitivity prevalence-dependent. A new statistic, the percent of Negative pap smears with detectable high-risk human papillomavirus, is posited, which may be important if human papillomavirus DNA testing is used clinically.

Cervix Uteri↗

PubMed2004

Using urbanization profiles to assess screening performance.

The large Dutch data sets acquired as a result of population-based cervical smear screening programs can be further exploited to obtain an urbanization-weighted score to gain insight into the quality of the performance of the individual cytology laboratories. Based on the first four digits of the postal code of the screenees, the data are stratified according to urbanization. Urb 1 corresponds to (semi)rural, which includes villages and small townships with less than 20,000 inhabitants; Urb 2, to towns with between 20,000 and 250,000 inhabitants; and Urb 3, to big cities, in this case, The Hague. From the postal code data of the screenees, the urbanization profiles of the laboratories can be calculated. The urbanization degree proved to have a substantial effect on the cytologic scores in the four laboratories. The number of expected, urbanization-weighted patient cases is calculated. Accordingly, the laboratories could be compared with respect to performance. We conclude that laboratories in our screening program were quite similar in performance for the cytologic diagnosis leading to referral to the hospital, with little difference between the actual and the expected, urbanization-weighted number of cases. It is evident that the equation for calculating the expected scores for S5-S9 is relevant for control of quality of care provided by laboratories and regions, but also for the quality of these assessments.

Female↗

PubMed2003

Urbanization and the incidence of abnormalities of squamous and glandular epithelium of the cervix.

BACKGROUND: The large data bases of the Dutch cervical screening program can be exploited to establish the relation between urbanization and the incidence of abnormalities of the squamous and glandular epithelium, including mild or greater changes of the squamous and glandular epithelium of the cervix. METHODS: Six cytology laboratories in the context of the Dutch cervical screening program screened over 190,000 cervical smears. Urbanization (place of residence) data were derived from postal codes. All smears were coded with the Dutch national coding system, the Dutch national classification system KOPAC, in which squamous abnormalities are coded S4-S9, and glandular cell changes are coded G4-G9. From the scores per 1000 screened women, the relative risk (RR) of living in a large city compared with living in rural areas was calculated. To investigate a trend in incidence in relation to urbanization, the Schaafsma method was used. RESULTS: Of the smears with positive cytology, mild squamous dysplasia (S4) had the highest incidence per 1000 screened women (4.32), and the lowest incidence was found for adenocarcinoma (in situ; G7/G9; RR, 0.07). The RR for urban women ranged from 1.73 for moderate squamous dysplasia (S5) to 7.55 for adenocarcinoma (in situ; G7/G9). For smears with positive cytology for both squamous and glandular abnormalities, the Schaafsma method indicated a significant positive trend. CONCLUSIONS: The incidence of squamous and glandular abnormalities are maximal in women who live in a large city, which, in The Netherlands, is where there also is a population at high risk for human papillomavirus and bacterial vaginosis.

Adenocarcinoma↗

PubMed2002

Urbanization and baseline prevalence of genital infections including Candida, Trichomonas, and human papillomavirus and of a disturbed vaginal ecology as established in the Dutch Cervical Screening Program.

OBJECTIVE: An overgrowth of coccoid bacilli in the absence of lactobacilli (bacterial vaginosis) is considered a sign of a "disturbed" vaginal ecologic system. The aim of this study was to establish the baseline prevalence of genital infections and of a disturbed vaginal ecologic system and their relationship to urbanization. STUDY DESIGN: More than 190,000 cervical smears were screened by 1 cytology laboratory in the context of the Dutch national screening programs. The women who were symptom free and had been registered in the statutory files of municipal units were screened by invitation. Urbanization (place of residence) was derived from the postal code. To investigate a trend in prevalence in relation to urbanization, Schaafsma's method was used. RESULTS: Bacterial vaginosis had the highest score per 1000 screened women (36.1), followed by Candida (12.6). Higher prevalence of human papillomavirus, bacterial vaginosis, and Trichomonas was related to urbanization as was, whereas Candida was not. CONCLUSION: Human papillomavirus and Trichomonas are more frequently found in women who live in the large cities, which in The Netherlands also harbor the high-risk population for premalignant cytologic evidence. Our findings concerning the baseline prevalence pattern of bacterial vaginosis support the hypothesis of the importance of a disturbed bacterial ecologic system in cervical carcinogenesis.

Adult↗

PubMedDate not supplied

Diagnostic parameters in liquid-based cervical cytology using a coagulant suspension fixative.

OBJECTIVE: To evaluate in detail the morphology of cervical cell samples suspended in the coagulant fixative BoonFix (Finetec, Tokyo, Japan) in liquid-based Papspin slides (Thermo Shandon, Pittsburgh, Pennsylvania, U.S.A) to detect shifts in diagnostic parameters for infections and neoplasia. STUDY DESIGN: Split samples of 1,010 cases were collected. All Papspin slides were scanned with neural network technology. In 849 cases the diagnosis was "within normal limits"; in 22 cases it was preneoplasia. In 151 special cases conventional smears were compared with thin-layer slides. RESULTS: In 85% of the 151 special cases, a shift of the diagnostic parameter was observed in the Papspin slide. The parameter adhesion of inflammatory cells to epithelial cells was easier to discern in 94% of the cases, and adhesion of microorganisms varied 43-100%. Koilocytosis was more visible in 79%. Prominent nucleoli in atypical and malignant cells were enhanced in 50-100% of cases with preneoplasia. The fact that the cells on the Papspin slide were no longer present in diagnostic streaks posed a problem only in the case of follicular cervicitis. CONCLUSION: The shifts in parameters facilitated the diagnostic process. BoonFix permits the screening of liquid-based Papspin slides, which have proven to be well suited to automated neural network scanning.

Bacterial Infections↗

PubMedDate not supplied

Population-based cervical screening with a 5-year interval in The Netherlands. Stabilization of the incidence of squamous cell carcinoma and its precursor lesions in the screened population.

OBJECTIVE: To evaluate the outcome of population-based cervical screening at 5-year intervals. STUDY DESIGN: Results from the west region of the Netherlands (population 2 million) were used. The 1995-2000 round was compared with the first 2 years of the second (2001-2002). All results were prospectively collected in a central database. Positive cytologies and histoscores per 1,000 screened for preinvasive squamous cervical intraepithelial neoplasia (CIN) lesions and invasive squamous cell carcinoma were calculated. RESULTS: In the first round, 378,081 women were screened; in the second round, 100,561 women were screened. In both rounds the youngest screenees had the highest cytoscores. Cytoscores in the first round did not differ significantly from those in the second. The histoscore for CIN 1 and 2 was 1.42 per 1,000 in the first round and 1.18 per 1,000 (NS, P < .01) in the second. The histoscore for CIN 3 was 2.07 per 1,000 in the first round and 2.13 per 1,000 (NS, P < .01) in the second. Histoscores for invasive squamous cell carcinoma remained virtually the same (0.16 per 1,000 in the first, 0.14 per 1,000 in the second round). CONCLUSION: Population-based screening at 5-year intervals in the Netherlands may result in stabilization of positive cytology and of the incidence of CIN and (histologic) invasive squamous cell carcinoma. The program seems more cost effective than that of 2 decades ago, with a screening interval of 3 years.

Adult↗