PubMed Health⌕ Search

Biomedical subjects

M M van der Linden

Publications and source records attributed to M M van der Linden.

12 recordsLinked to original sources
PubMed1993

Can the same edge-detection algorithm be applied to on-line and off-line analysis systems? Validation of a new cinefilm-based geometric coronary measurement software.

In the Cardiovascular Measurement System (CMS) the edge-detection algorithm, which was primarily designed for the Philips digital cardiac imaging system (DCI), is applied to cinefilms. Comparative validation of CMS and DCI was performed in vitro and in vivo with intracoronary insertion of stenosis phantoms in anesthetized pigs. The "obstruction diameter" (OD) was measured at the artificial stenoses visualized by angiography with calibration at the isocenter (ISO) and catheter calibration (CATH) and compared with the true phantom diameters. A clinical comparison of OD, reference diameter (RD), and percentage diameter stenosis (DS) was performed on 70 corresponding images from post-PTCA angiograms. In vitro, OD (CMS) yielded an accuracy of 0.18 +/- 0.14 mm with 100% (correlation coefficient: r = 0.97, y = 0.06 + 0.75x, standard error of estimate [SEE] = 0.09) and 0.19 +/- 0.15 mm with 50% contrast (r = 0.94, y = 0.02 + 0.81 x). OD (DCI) yielded an accuracy of 0.11 +/- 0.06 mm with 100% (r = 0.99, y = -0.03 + 0.91 x, SEE = 0.05) and 0.24 +/- 0.13 mm with 50% contrast (r = 0.94, y = 0.29 + 6.69 x, SEE = 0.12). In vivo, OD (CMS) yielded an accuracy of 0.18 +/- 0.23 mm with ISO (r = 0.89, y = 0.02 + 0.83 x, SEE = 0.22) and 0.26 +/- 0.24 mm with CATH (r = 0.89, y = 0.06 + 0.72 x, SEE = 0.19). OD (DCI) yielded an accuracy of 0.08 +/- 0.15 mm with ISO (r = 0.96, y = 0.08 + 0.86 x, SEE = 0.14) and 0.18 +/- 0.21 mm with CATH (r = 0.92, y = 0.09 + 0.76 x, SEE = 0.17). The clinical comparison showed reasonable agreement for OD only (r = 0.81, y = 0.26 + 0.81 x, SEE = 0.29). Transformation of an edge-detection algorithm from a digital to a cinefilm-based system can lead to impairment of measurement reliability.

Algorithms↗
PubMed1992

Prevalence of human papillomavirus infections among heterosexual men and women with multiple sexual partners.

A prospective study of 65 men and 111 women with multiple heterosexual partners was designed to assess the prevalence and potential risk factors of genital human papillomavirus (HPV) infections. In addition, the HPV reservoir in genital, rectal, and oral mucosa was examined. The specimens for the detection of HPV DNA were taken from different sites such as the urethra and coronal sulcus (men), cervix and labia minora (women), anus, rectum, tongue, and buccal mucosa (both men and women). Women underwent speculum examination and colposcopic evaluation of the anogenital region, and a smear for routine cytological classification was also taken. In men, the anogenital region was examined clinically and colposcopically. The polymerase chain reaction (PCR) was used for the detection of HPV types 6/11, 16, 18, and 33. A high prevalence of HPV infection at one or more sites was detected, in 32% of the male and in 23% of the female participants. Seventeen percent of the male distal urethral specimens were positive for HPV DNA. From the female cervical specimens 14% were found positive. Ten proctal specimens (five men and five women) were positive for HPV DNA without any discernible lesion. The persons from whom these samples were taken denied anal insertive intercourse. No oral manifestation of HPV infection was detected. In both men and women a difference between HPV DNA-positive and -negative persons was not found in relation to known risk factors associated HPV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Prevalence of hepatitis C virus infections among heterosexuals with multiple partners.

A study among heterosexual men and women with multiple sexual partners was carried out to assess the seroprevalence of antibody against hepatitis C virus (HCV). The 468 participants were recruited among visitors to the Clinic for Sexually Transmitted Diseases in Amsterdam. Sera were tested by an enzyme-linked immunosorbent assay (ELISA; Ortho), a recombinant-based immunoblot assay (RIBA; Chiron), and the polymerase chain reaction (PCR). A total of 468 persons were tested, and seven (1.5%) were found ELISA positive. Another 25 (5%) were ELISA indeterminate. Six of the seven ELISA-positive cases were RIBA positive. Further serum samples from five HCV ELISA-positive persons were tested by PCR, and four were found to be positive. The HCV ELISA-positive/RIBA-indeterminate reaction was PCR negative. None of the 17 RIBA-tested sera of the ELISA-indeterminate group yielded a positive result. There was a good correlation between an ELISA optical density/cut-off ratio greater than 2 and a positive RIBA result. The risk factor for HCV appeared to be the type of sexual partner, i.e., belonging to a "high-risk" group for human immunodeficiency virus infection and origin from hepatitis B-endemic countries. It is concluded that HCV may be transmitted through heterosexual contact but probably with low efficiency.

Adult↗
PubMed1991

Limited changes in sexual behaviour of heterosexual men and women with multiple partners in The Netherlands.

To study changes in sexual behaviour, heterosexuals with multiple sexual partners were recruited through an STD-clinic and asked to return every 4 months for follow-up. Between October 1987 and June 1989, 512 heterosexuals entered the study and 140 men and 200 women had at least one follow-up visit. No changes were found between 3 visits in the kind of sexual techniques practiced. Condom use during vaginal intercourse with commercial partners (prostitutes or clients) was relatively high and remained high, but was low and remained at that level with private partners. Men and women reduced their number of private sexual partners by 50%, but the decline in the number of commercial partners was nonsignificant. Although more information is needed about the underlying social-psychological aspects of behavioural change, it seems necessary to redesign prevention activities to stress the effectiveness of condoms and to encourage condom use especially among heterosexuals with multiple private partners.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The importance of ethnicity as a risk factor for STDs and sexual behaviour among heterosexuals.

OBJECTIVES: To study risk factors for sexually transmitted diseases (STDs) and sexual behaviour. Especially to assess whether there is a higher risk of being infected with STDs among ethnic minorities, and if so for what reasons. SETTING: STD-clinic of the Municipal Health Service of Amsterdam, the Netherlands. SUBJECTS: Cross-sectional study of heterosexuals (255 men and 343 women) with multiple sexual partners, who participated between October 1987 and January 1990. RESULTS: Besides STD-related complaints, ethnicity was an important independent predictor of one or more diagnosed genital STDs. STD-prevalence was higher among men born in Turkey (47%, OR = 3.4) and men born in Surinam (36%, OR = 2.1), compared with Dutch men (21%). While Turkish men had mainly riskful sexual behaviour with prostitutes, Surinam men had more often riskful sexual contact with private partners. Among women, STD prevalence was higher among West-European (38%, OR = 2.3) and Latin-American women (30%, OR = 1.6), compared with Dutch women (21%). Latin American women had more often riskful sexual contact with clients; sexual behaviour of West-European women was riskful with both clients and private partners. CONCLUSIONS: Prevention activities should be directed at specific sexual and ethnic groups, sources of information should be carefully selected, and some groups should be addressed differently with regard to language but to content as well.

Adult↗
PubMed1990

[HIV prevalence among heterosexual subjects with multiple partners in Amsterdam].

To study the prevalence of HIV-infection among heterosexuals with multiple partners, participants were recruited from a STD clinic in Amsterdam. In 1988, 785 visitors met the selection criteria, of whom 361 (46%) finally participated. An HIV prevalence of 2/361 (0.6%) was found among participants. To test representativity, participants and refusers were compared on demographic characteristics and prevalence of STDs. Male refusers were on average younger, had on average fewer partners and relatively more often had a foreign nationality. Female refusers had on average fewer partners. No differences were found in the prevalence of STDs between participants and refusers. Because of the high refusal rate and differences between participants and refusers, the HIV prevalence found is not representative of heterosexuals with multiple partners.

Adult↗
PubMed1990

Prevalence of human T-cell leukemia virus antibody among heterosexuals living in Amsterdam, The Netherlands.

To determine the heterosexual spread of human T-cell leukemia virus (HTLV-I) infections, a cohort of 472 individuals with more than 5 heterosexual partners in the 6 months before entry was studied. They were recruited from visitors to the Clinic for Sexually Transmitted Diseases of the Municipal Health Service. Half of the study group was born in the Netherlands, 13% in Surinam or the Dutch Antilles, and 8% in Turkey or Morocco. Seventy percent were involved in commercial sex. Three persons were positive for HTLV-I, with serum antibodies against p19, p24, p28, gp46, and gp61 in Western immunoblot (WIB) and radio-immunoprecipitation assay (RIPA). Two of them originated from Surinam and the third was a Dutch woman. Two other individuals were HIV-positive, 19% had hepatitis B virus (HBV)-markers and 6% Treponema pallidum reacted in the hemagglutination assay (TPHA). It is concluded that HTLV-I circulates in the Surinamese population in Amsterdam and there was no evidence of appreciable heterosexual transmission.

Adult↗
PubMed1989

[Incidence of sexually transmissible disorders in clients of 2 ambulatory venereal disease clinics in Amsterdam, 1981-1987].

Since 1981 sexually transmitted diseases (STD) diagnosed at the STD clinics of the Municipal Health Service of Amsterdam, are registered by sex, sexual orientation and prostitution. Numbers of diagnoses per 1,000 new consultations are compared for each group of visitors over the period 1981-1987. Among heterosexual visitors there has been a steady decline of gonorrhoea and trichomoniasis since 1981. Genital herpes and venereal warts after increasing until 1985 have reached a plateau. Because of the early appearance of these trends they cannot be attributed to changes in heterosexual behaviour brought about by the AIDS epidemic. Nongonococcal urethritis has been increasing since 1981, possibly due to insufficient Chlamydia trachomatis detection in the country. After several years of decline, early syphilis has been increasing since 1987 among heterosexual men and women. Among homo/bisexual men the numbers of cases of gonorrhoea and early syphilis as well as the number of consultations for STD have decreased strongly since 1984, which may well be the result of changes in homosexual behaviour because of AIDS.

Ambulatory Care Facilities↗
PubMed1989

Heterosexuals at risk for HIV: differences between private and commercial partners in sexual behaviour and condom use.

To study the prevalence of HIV and other sexually transmitted diseases (STDs), sexual behaviour and condom use among heterosexuals, 193 women and 157 men entered a longitudinal study. Participants were recruited through an STD clinic, and had had five or more heterosexual partners in the preceding 6 months but had no other AIDS risk factors. Participants were divided in groups with respect to private and/or commercial sexual partners. One hundred and thirty-six (71%) women worked as prostitutes and had, on average, 115 customers a month, and 99 (63%) men had visited, on the average, eight prostitutes in the past 4 months. One hundred and seventy-one (89%) women (114 prostitutes) had had, on average, four partners, and 112 (78%) men (of whom 64 had visited prostitutes) had had, on average, seven private partners in the past 4 months. Vaginal intercourse was often or always reported by all participants whilst anal contact was seldom reported. Non-high-risk sexual techniques (for example, oro-oral, masturbation) were practised more frequently with private than with commercial partners (P less than 0.001). Although no differences were found in the frequency of practising high-risk sexual techniques (for example, vaginal, ano-genital), differences were found for frequency of condom use. Condom use during vaginal intercourse was reported more frequently with commercial than with private partners (P less than 0.01). However, if the number of partners is taken into account, prostitutes had unprotected vaginal intercourse with an estimated average number of 160 partners in 4 months, which is far more than customers (seven) and men and women with private partners only (four).(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗