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Biomedical subjects

M Prins

Publications and source records attributed to M Prins.

At least 37 records · Page 2Linked to original sources
PubMed2000

Risk factors for human herpesvirus 8 seropositivity and seroconversion in a cohort of homosexual men.

Sexual and nonsexual modes of transmission of human herpesvirus 8 (HHV8) have been suggested, but specific routes remain unclear. Therefore, the objective of this study was to assess risk factors for HHV8 seropositivity and determine specific sexual practices associated with HHV8 seroconversion. Sera from 1,458 homosexual men (Amsterdam Cohort Study, 1984-1996) were tested for antibodies to HHV8 with a modified version of an enzyme immunoassay, using recombinant HHV8 lytic phase capsid (ORF65) and latent phase nuclear (ORF73) proteins. HHV8 seroprevalence at study entry was 20.9% (305/1,458); was highest among those with positive human immunodeficiency virus (HIV) status, no steady partner, and southern European or Latin American nationality; and increased with older age and higher number of sexual partners. During follow-up, 215 men seroconverted for HHV8 (incidence: 3.6/100 person-years). Both prevalence and incidence rates remained more or less stable during the study period. Orogenital insertive sex (odds ratio (OR) = 5.95; 95% confidence interval (CI): 2.88, 12.29) or orogenital receptive sex (OR = 4.29; 95% CI: 2.11, 8.71) with more than five partners in the past 6 months, older age (OR = 2.89; 95% CI: 1.13, 7.34, when older than 45 years), and preceding HIV infection (OR = 2.47; 95% CI: 1.53, 3.99) were independent predictors for HHV8 seroconversion. The authors found strong evidence for orogenital transmission of HHV8 among homosexual men.

Adult↗
PubMed2000

Greater late lumen loss after successful coronary balloon angioplasty in the proximal left anterior descending coronary artery is not explained by extent of vessel wall damage or plaque burden.

OBJECTIVES: We investigated whether the greater late lumen loss after coronary balloon angioplasty in the proximal left anterior descending artery (P-LAD) compared with that in other segments might be related to differences in vascular dimensions or morphology as determined by angiography and intravascular ultrasound imaging. BACKGROUND: The greater late lumen loss after angioplasty in the P-LAD that has been observed in several studies has not been explained. METHODS: We studied 178 patients and 194 coronary artery lesions by quantitative angiography and 30 MHz intravascular ultrasound imaging after successful balloon angioplasty. Vessel wall morphology was compared among three proximal and three nonproximal segments. Follow-up quantitative angiography for late lumen loss calculation was performed in 168 lesions. Multivariate analysis was used to determine predictors of late lumen loss. RESULTS: Absolute and relative late loss were significantly greater at the P-LAD compared with the pooled group of other segments (0.42 +/- 0.60 mm vs. 0.10 +/- 0.48 mm, p = 0.0008 and 0.14 +/- 0.24 vs. 0.03 +/- 0.17, p < 0.001). Also, a greater percentage of calcific lesions (65% vs. 44%, p = 0.034), a lower incidence of rupture (51% vs. 74%, p = 0.009) and a larger reference segment plaque area (5.4 +/- 2.2 mm2 vs. 4.7 +/- 1.9 mm2, p = 0.05) were found in the P-LAD. In multivariate analysis however, these variables were not predictive of late loss. CONCLUSIONS: Greater late lumen loss after coronary balloon angioplasty of the P-LAD is not explained by differences in atherosclerotic plaque burden or in vessel wall damage.

Aortic Dissection↗
PubMed2000

The natural course of Gaucher disease in The Netherlands: implications for monitoring of disease manifestations.

This retrospective study in 20 untreated type I Gaucher disease patients shows that in Dutch patients clinical manifestations of Gaucher disease type I are progressive in the majority of patients, children as well as adults. This is in contrast with studies among Jewish patients. Our results emphasize the need for a regular follow-up to enable timely initiation of enzyme therapy.

Adolescent↗
PubMed2000

Constitutive expression of interferon-induced human MxA protein in transgenic tobacco plants does not confer resistance to a variety of RNA viruses.

MxA is a key component in the interferon-induced antiviral defense in humans. After viral infections, MxA is rapidly induced and accumulates in the cytoplasm. The multiplication of many RNA viruses, including all bunyaviruses tested so far, is inhibited by MxA. These findings prompted us to express MxA in plants in an attempt to create resistance to tospoviruses. Here, we report the generation of transgenic tobacco plants that constitutively express MxA under the control of the 35 S cauliflower mosaic virus promotor. Northern and western blot analysis confirmed the expression of MxA in several transgenic plant lines. MxA expression had no obvious detrimental effects on plant growth and fertility. However, challenge experiments with tomato spotted wilt virus, tomato chlorotic spot virus, and groundnut ringspot virus revealed no increased resistance of MxA-transgenic tobacco plants to tospovirus infections. Neither was the multiplication of tobacco mosaic virus, cucumber mosaic virus and potato virus Y inhibited in MxA-transgenic plants. The results indicate that the expression of human MxA alone does not enhance virus resistance in planta.

GTP-Binding Proteins↗
PubMed2000

Videodensitometric quantitative angiography after coronary balloon angioplasty, compared to edge-detection quantitative angiography and intracoronary ultrasound imaging.

AIMS: To assess the value of videodensitometric quantification of the coronary lumen after angioplasty by comparison to two other techniques of coronary artery lumen quantification. METHODS AND RESULTS: Videodensitometric quantitative angiography, edge detection quantitative angiography and 30 MHz intracoronary ultrasound imaging were performed after successful balloon angioplasty in 161 patients. Lumen cross-sectional areas were mean (SD) 2.82 (1.15) mm(2)for edge detection quantitative angiography, 3.67 (1.5) mm(2)for videodensitometric quantitative angiography and 5.32 (1.75) mm(2)for intracoronary ultrasound imaging (P<0.001). The correlation between intracoronary ultrasound imaging and videodensitometric quantitative angiography (r=0.44) was almost similar to that of intracoronary ultrasound imaging and edge detection quantitative angiography (r=0. 47). The correlation between the three techniques was not significantly influenced by the presence of ruptures and dissections on intracoronary ultrasound imaging. The absence of calcifications improved the correlation between videodensitometry and intracoronary ultrasound imaging. CONCLUSIONS: The luminal dimensions as measured by videodensitometric quantitative angiography matched intracoronary ultrasound imaging derived dimensions more closely than edge detection quantitative angiography. Videodensitometric quantitative angiography represents an on-line alternative to intracoronary ultrasound imaging for quantitative analysis regardless of the degree of vessel damage.

Absorptiometry, Photon↗
PubMed1999

Do gender differences in CD4 cell counts matter?

OBJECTIVE: To examine the effect of gender on disease progression and whether gender differences in CD4 lymphocyte counts persisted for the entire course from HIV seroconversion until (death from) AIDS. METHODS: CD4 lymphocyte counts were modelled in 221 female and 443 male seroconverters following seroconversion, backwards from AIDS and backwards from death using regression analysis for repeated measurements. RESULTS: In the period before use of highly active antiretroviral therapy (HAART), progression to AIDS and to death were marginally slower in women than in men as assessed by proportional hazards analysis. Women seroconverted for HIV, developed AIDS and died at higher CD4 cell counts than men (women: 815, 146 and 44 x 10(6) cells/l, respectively; men: 727, 49 and 22 x 10(6) cells/l, respectively), although differences were only statistically significant at AIDS onset. Declines in CD4 lymphocyte counts were not significantly affected by gender and absolute differences between men and women were stable, with exception for the trajectory close to AIDS when the decline became steeper for men than women. CONCLUSION: These gender differences in CD4 lymphocyte counts suggest a delay of initiation of therapy in women compared with men (our model predicted that women reach the threshold of starting HAART at about 12 months later than men). If this delay unfavourably influences progression, treatment guidelines should be revised so that women can benefit equally from HAART.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Recurrent venous thrombosis and heparin therapy: an evaluation of the importance of early activated partial thromboplastin times.

BACKGROUND: The presence of an association between early subtherapeutic activated partial thromboplastin times (aPTTs) and recurrent venous thromboembolism (VTE) remains controversial. OBJECTIVE: To determine the relation between early subtherapeutic aPTTs and recurrent VTE in patients who were treated with intravenous (i.v.) unfractionated heparin (UFH). PATIENTS AND METHODS: We studied 961 patients with acute VTE who received i.v. UFH in 3 randomized trials that compared the use of i.v. UFH (loading dose: 5000 U i.v.; initial infusion, 1250-1280 U/h) with that of subcutaneous low-molecular-weight heparin. According to aPTT criteria, patients were classified as being in a subtherapeutic or a therapeutic state during the first 24 and 48 hours of treatment. All episodes of possible recurrent VTE were adjudicated by an independent committee that was unaware of the aPTTs. RESULTS: At 24 hours, in 886 patients who were eligible for the analysis, the rate of recurrent VTE in the subtherapeutic group was 6.7% (11/163) compared with 5.3% (38/723) in the therapeutic group. The odds ratio for recurrence in patients in the subtherapeutic vs the therapeutic group at 24 hours was 1.30 (95% confidence interval: 0.64-2.63; P = .46). At 48 hours, in 917 patients who were eligible for the analysis, the rate of recurrent VTE in the subtherapeutic group was 7.8% (5/64) compared with 5.7% (49/853) in the therapeutic group. The odds ratio for recurrence in patients in the subtherapeutic vs the therapeutic group at 48 hours was 1.32 (95% confidence interval: 0.51-3.44; P = .56). CONCLUSION: In patients with acute VTE who receive an i.v. bolus of 5000 U, followed by a starting dose of at least 1250 U/h of UFH, a subtherapeutic aPTT response during the first 48 hours of treatment is not associated with a large increase in the risk of recurrent VTE.

Aged↗
PubMed1999

Value of brush cytology for dominant strictures in primary sclerosing cholangitis.

BACKGROUND AND STUDY AIMS: Around 10% of patients with primary sclerosing cholangitis (PSC) develop cholangiocarcinoma, which is cholangiographically often indistinguishable from a benign dominant stricture. The aim of the present study was to assess the value of brush cytology in discriminating between benign and malignant dominant strictures in primary sclerosing cholangitis. PATIENTS AND METHODS: The results of all brush cytology specimens from dominant strictures from patients with established primary sclerosing cholangitis, taken at endoscopic retrograde cholangiopancreatography between 1987 and 1996, were compared with the histological diagnosis or clinical status of the patients at least 2 years later. RESULTS: A total of 47 brush cytology samples, taken between 1987 and 1996, from 43 PSC patients could be included. Between 1993 and 1996, p53 immunocytochemical examination was done in 27 brush cytology specimens and K-ras mutation analysis in 25 patients. The sensitivity, specificity, positive predictive value, and negative predictive value of brush cytology for detection of malignancy were 60%, 89%, 59%, and 89%, respectively. These figures were not improved by adding the results of p53 and K-ras analysis. Logistic regression analysis did not reveal any additional benefit of p53 or K-ras analysis either. Prior stenting did not adversely affect specificity. CONCLUSIONS: The sensitivity and positive predictive value of brush cytology for dominant strictures in PSC are rather poor. The specificity and negative predictive value are reasonably good. There was no additional value from p53 immunocytochemistry and K-ras mutation analysis. Prior stenting did not affect the results.

Bile Duct Neoplasms↗
PubMed1999

Geographical variation in disease progression in HIV-1 seroconverted injecting drug users in Europe?

BACKGROUND: Human immunodeficiency virus (HIV) disease progression might vary by geographical region due to differences in the spectrum of HIV-related illnesses and (access to) health care. Therefore, the effect of geographical region, next to the effect of other potential cofactors, on disease progression in 664 injecting drug users (IDU) with documented HIV seroconversion from eight cohorts in Europe was studied. METHODS: Kaplan-Meier methods and Cox proportional hazards analysis were performed to assess the effect of geographical region, other sociodemographics, drug use and repeated HIV exposure on progression from HIV seroconversion to immunosuppression, AIDS and death with AIDS. We considered the confounding effect of study-design related factors (e.g. setting of follow-up), and accounted for pre-AIDS death from natural causes by imputing when each endpoint would have occurred, had they not died without AIDS. RESULTS: Estimates of progression to AIDS and death with AIDS were substantially faster after taking pre-AIDS mortality into account. Median incubation time from seroconversion to the first CD4 count < 200 cells/microliter was 7.7 years (95% CI: 7.1-8.3) and to AIDS 10.4 years (95% CI: 9.8-infinity). The 10-year survival was 70.3% (95% CI: 62.8-76.6). The relative hazards (RH) of AIDS for IDU from central and southern Europe compared with IDU from northern Europe was 1.9 (95% CI: 1.2-3.0) and 1.2 (95% CI: 0.6-2.3), respectively, before, and 1.5 (95% CI: 0.7-3.2) and 1.1 (95% CI: 0.6-2.3) after taking differences in study-design related factors into account. Accounting for these factors, the RH of death with AIDS was 0.9 (95% CI: 0.3-2.5) for central and 1.2 (95% CI: 0.4-3.4) for southern Europe compared with northern Europe. For the first CD4 count < 200 cells/microliter these figures were 0.8 (95% CI: 0.5-1.4) and 0.8 (95% CI: 0.5-1.4). Age at seroconversion was the strongest predictor of disease progression. No statistically significant differences in disease progression were found by gender, foreign nationality, drug use and potential repeated HIV exposure. CONCLUSIONS: We found no evidence for regional variability in HIV disease progression among European IDU. Future studies evaluating geographical differences should consider the confounding effect of study-design related factors and differential non-AIDS mortality. As age is an important determinant of disease progression, it should be considered in recommending treatment.

Adult↗
PubMed1998

Low T-cell responses to CD3 plus CD28 monoclonal antibodies are predictive of development of AIDS.

OBJECTIVE: Decreased T-cell reactivity in vitro is strongly associated with progression to AIDS and low CD4+ T-cell numbers. Low T-cell responses in vitro induced by CD3 monoclonal antibody (mAb) are predictive for progression to AIDS independent of low CD4+ T-cell counts and high HIV-1 RNA levels. We developed a whole-blood lymphocyte culture system in which T cells were stimulated by a combination of CD3 and CD28 mAb. Combined stimulation of CD28, a costimulatory molecule, and CD3 considerably enhances T-cell responses in vitro and reduces variation coefficients, which may increase the prognostic power of T-cell responses. DESIGN: A prospective study of HIV-1-infected homosexual men followed for 35 months. METHODS: The predictive value of low T-cell responses to CD3 plus CD28 mAb relative to low CD4+ T-cell counts, high HIV-1 RNA levels and the presence of syncytium-inducing (SI) HIV-1 variants was evaluated longitudinally in 202 HIV-1-infected homosexual men followed for 35 months. RESULTS: In multivariate analysis, decreased T-cell responses at baseline were predictive of development of AIDS, independent of low CD4+ T-cell numbers and high HIV-1 RNA levels. In a time-dependent model, HIV-1 RNA levels lost their predictive value, whereas low T-cell responses, low CD4+ T-cell numbers and the presence of SI HIV-1 variants independently predicted AIDS. CONCLUSIONS: These data demonstrate that combined use of virological and immunological markers may be useful in monitoring disease progression and response to antiretroviral therapy.

Antibodies, Monoclonal↗
PubMed1998

A common mutation in the lipoprotein lipase gene (N291S) alters the lipoprotein phenotype and risk for cardiovascular disease in patients with familial hypercholesterolemia.

BACKGROUND: Recently, a mutation in the lipoprotein lipase (LPL) gene (N291S) has been reported in 2% to 5% of individuals in western populations and is associated with increased triglyceride (TG) and reduced HDL cholesterol (HDLC) concentrations. METHODS AND RESULTS: Here we report a significant alteration in biochemical and clinical phenotype in subjects with familial hypercholesterolemia (FH) who are heterozygous for this N291S LPL mutation. Sixty-four FH heterozygotes carrying the N291S mutation had significantly a higher TG level (P=.004), a higher ratio of total cholesterol to HDLC (P<.001), and lower HDLC concentrations (P=.002) compared with 175 FH heterozygotes without this LPL mutation. Moreover, the N291S mutation conferred a significantly greater risk for developing cardiovascular disease in FH heterozygotes compared with FH heterozygotes without this LPL mutation (odds ratio, 3.875; P=.006). CONCLUSIONS: These data provide evidence that a common LPL variant (N291S) significantly influences the biochemical phenotype and risk for cardiovascular disease in patients with FH.

Adult↗
PubMed1998

The emerging problem of tospovirus infection and nonconventional methods of control.

The emergence of tospoviruses as a significant problem in the cultivation of many crops around the world makes it vital to develop strategies to restrain these viruses. So far, only a few natural resistance genes suitable for introduction into plant breeding programs have been identified, prompting the exploitation of alternative ways of introducing virus resistance into crop plants, such as genetic modifications.

Animals↗
PubMed1998

Skin irritation by dithranol cream. A blind study to assess the role of the cream formulation.

In connection with a national cost-effective evaluation study of short contact dithranol therapy for psoriasis, the question arose whether dithranol cream irritation is influenced by constituents of the vehicle. To establish the role of the different components of the vehicle in the mechanism of dithranol irritation, the dithranol 3% cream used in the evaluation study and its vehicle with nine different combinations of its components were tested in a blind study. The creams were applied for 15, 30 and 45 min on the backs of 12 healthy volunteers. Irritation was scored as erythema by visual and colorimeter scoring. The dithranol creams with salicylic acid among their stabilizers showed 42% more irritation than the dithranol creams with only sorbic acid or no stabilizers at all. Stability tests showed no significant degradation of dithranol in the two less irritating creams when kept at 4 degrees C for 11 months. Salicylic acid in the cream aggravates dithranol-induced erythema.

Administration, Topical↗