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B Janssen

Publications and source records attributed to B Janssen.

At least 55 records · Page 3Linked to original sources
PubMed1995

Laxity characteristics of normal and pathological murine knee joints in vitro.

The aim of this study was to validate a device developed previously to measure laxity of murine knee joints and to investigate whether experimentally induced pathological conditions result in measurable laxity. The laxity characteristics of normal murine knee joints were derived from measurements of 25 left knees of normal mice. Reproducible, nonlinear s-shaped load-displacement curves were determined, and parameters of anterior-posterior translation, varus-valgus rotation, and compliance were calculated from the curves. No differences were found between the left and right knee joints of eight mice. The average displacement between 0.8 N of anterior force and 0.8 N of posterior force was 0.47 +/- 0.10 mm. The endpoint compliances for anterior and posterior displacements were 0.16 +/- 0.03 and 0.16 +/- 0.04 mm/N, respectively. The average rotation between a 4 Nmm valgus moment and a 4 Nmm varus moment was 17.4 +/- 3.3 degrees. The endpoint compliances for varus and valgus rotations were 1.1 +/- 0.7 and 1.0 +/- 0.3 degrees/Nmm, respectively. Storage of the joints at -70 degrees C had no effect on laxity. We also studied the parameters of laxity after pathology of the knee joint was induced. Zymosan-induced or antigen-induced arthritis did not increase laxity of the joint. In an osteoarthritis model induced by injection of collagenase, laxity was markedly increased. In conclusion, laxity in the knees of mice can be measured reproducibly and changes in the characteristics of laxity due to pathological conditions can be quantified.

Animals↗
PubMed1995

Cosmid contigs from the tuberous sclerosis candidate region on chromosome 9q34.

Tuberous sclerosis (TSC) is a heterogeneous multisystem disorder with loci on 9q34 (TSC1) and 16p13.3 (TSC2). The TSC2 gene has recently been isolated, while the TSC1 gene has been mapped to a 5-cM region between the markers D9S149 and D9S114. In our effort to localise and clone TSC1, we have obtained three adjacent cosmid contigs that cover the core of the candidate region. The three contigs comprise approximately 600 kb and include 80 cosmids, 2 P1 clones, 1 YAC, 5 anonymous markers and 4 sequence-tagged sites. The ABO blood group locus, the Surfeit gene cluster, the dopamine beta-hydroxylase gene (DBH) and VAV2, a homologue of the vav oncogene, have all been mapped within the contigs. Exon trapping and mutation screening experiments, aimed at identifying the TSC1 gene, are currently in progress.

Bacteriophage P1↗
PubMed1994

Refined localization of TSC1 by combined analysis of 9q34 and 16p13 data in 14 tuberous sclerosis families.

Tuberous sclerosis (TSC) is a heterogeneous trait. Since 1990, linkage studies have yielded putative TSC loci on chromosomes 9, 11, 12 and 16. Our current analysis, performed on 14 Dutch and British families, reveals only evidence for loci on chromosome 9q34 (TSC1) and chromosome 16p13 (TSC2). We have found no indication for a third locus for TSC, linked or unlinked to either of these chromosomal regions. The majority of our families shows linkage to chromosome 9. We have refined the candidate region for TSC1 to a region of approximately 5 cM between ABL and ABO.

Chromosome Mapping↗
PubMed1994

A pleiotropic response is induced in F9 embryonal carcinoma cells and rhino mouse skin by All-trans-retinoic acid, a RAR agonist but not by SR11237, a RXR-selective agonist.

We evaluated SR11237, a retinoid X receptor (RXR)-specific compound, for its pharmacologic effects on cell differentiation in F9 embryonal carcinoma cells and rhino mouse epidermis. SR11237 can cause RXR/RXR homodimers to form and transactivate a reporter gene containing a RXR-response element. We confirmed, using nuclear receptor co-transfection assays in COS-1 cells, that SR11237 is effective at transactivating a chloramphenicol acetyltransferase reporter gene through RXRs but not retinoic acid receptors. When SR11237 was tested for its ability to modulate cell differentiation, it was inactive on F9 embryonal carcinoma cells and rhino mouse skin. Because differentiation in these systems is known to be regulated by RAR-specific compounds, such as all-trans-retinoic acid and (E)-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-1-prope nyl benzoic acid], our results with SR11237 are compatible with the concept that classical retinoid pleiotropic responses are mediated by RXR/RAR heterodimeric nuclear receptors rather than through RXR/RXR homodimers.

Animals↗
PubMed1994

Linkage of hereditary haemorrhagic telangiectasia to chromosome 9q34 and evidence for locus heterogeneity.

Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant disorder with unknown pathophysiology that is characterised by arteriovenous lesions and recurrent haemorrhage in virtually every organ. Linkage of HHT to markers on chromosome 9q has recently been reported. In this study we report confirmation of this localisation in three unrelated families of Dutch origin. A fourth unrelated HHT family, in which considerably fewer pulmonary arteriovenous malformations (PAVM) were present, yielded evidence for non-linkage to this region. We conclude that HHT is a genetically heterogeneous disorder and our results indicate that the presence of PAVM may be more common in patients with a chromosome 9 linked form of HHT than in patients with the non-linked form.

Chromosome Mapping↗
PubMed1993

Translocation of BCR to chromosome 9: a new cytogenetic variant detected by FISH in two Ph-negative, BCR-positive patients with chronic myeloid leukemia.

Leukemic cells from two patients with Philadelphia-negative chronic myeloid leukemia (CML) were investigated: 1) Cytogenetics showed a normal 46,XY karyotype in both cases, 2) molecular studies revealed rearrangement of the M-BCR region and formation of BCR-ABL fusion mRNA with b2a2 (patient 1) or b3a2 (patient 2) configuration, and 3) fluorescence in situ hybridization (FISH) demonstrated relocation of the 5' BCR sequences from one chromosome 22 to one chromosome 9. The ABL probe hybridized to both chromosomes 9 at band q34, while two other probes which map centromeric and telomeric of BCR on 22q11 hybridized solely with chromosome 22. For the first time, a BCR-ABL rearrangement is shown to take place on 9q34 instead of in the usual location on 22q11. A rearrangement in the latter site is found in all Ph-positive CML and in almost all investigated CML with variant Ph or Ph-negative, BCR-positive cases. The few aberrant chromosomal localizations of BCR-ABL recombinant genes found previously were apparently the result of complex and successive changes. Furthermore in patient 2, both chromosomes 9 showed positive FISH signals with both ABL and BCR probes. Restriction fragment length polymorphism (RFLP) analysis indicated that mitotic recombination had occurred on the long arm of chromosome 9 and that the rearranged chromosome 9 was of paternal origin. The leukemic cells of this patient showed a duplication of the BCR-ABL gene, analogous to duplication of the Ph chromosome in classic CML. In addition they had lost the maternal alleles of the 9q34 chromosomal region.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Autoregulation and non-homeostatic behaviour of renal blood flow in conscious dogs.

1. Spontaneously occurring haemodynamic variations within 4 h affecting renal blood flow (RBF) were compared with externally induced short changes of renal artery pressure (RAP) in conscious resting dogs. 2. In all animals in which RAP was servo-controlled (n = 6), perfect autoregulation of RBF was observed. 3. In all 4 h recordings of spontaneous renal blood flow (n = 9), certain combinations of blood pressure and blood flow occurred remarkably frequently as indicated by three-dimensional frequency distributions. 4. Cluster analysis demonstrated significant differences between these areas of accumulation (P < 0.001). The average number of 'set points' per 4 h session was 3.1 +/- 0.3. 5. The shift from one set point to another is probably mediated by multiple control systems impinging on renal haemodynamics as suggested by 1/f fluctuations. 6. In seven dogs, an additional renal venous catheter allowed measurements of the arterial-venous (A-V) oxygen partial pressure (PO2) difference as an indicator of the renal metabolic demand. An inverse relationship between A-V PO2 difference and RBF (Y = X(-0.034) + 40.9, r = -0.9, P < 0.001) was found, indicating that the metabolic demands vary little (if at all) between the different set points. 7. The presented data suggest a modified view of renal homeostasis. There exist distinct combinations between RBF and RAP, which are very stable. Autoregulation merely buffers the fluctuations around these set points.

Animals↗
PubMed1992

[Is there an unusual incidence of the manifestation of intracranial angiomas in pregnancy? Risk assessment based on 17,733 patients over 10 years].

From 1979-1988, 134 inpatients (m:f = 80:54) were treated because of an intracranial angioma (AVM). The male/female ratio was 3/2 in general as well as during the "reproductive age" (15-45 yrs). In 6 patients (20-27 yrs; grav 2/para 1: n = 3; grav 1/para 0: n = 3) the AVM became symptomatic during pregnancy (n = 4: 23-33 gestational week) or at birth (n = 2). In the group of the presently non-pregnant women (n = 40) 47 uncomplicated deliveries had occurred years before. We conclude that the available data neither allow us to reject nor to confirm the hypothesis that pregnancy and/or delivery influence the manifestation of cerebral AVMs. The reasons for this dilemma of epidemiology are discussed.

Adolescent↗
PubMed1991

[Experience with hydrophilic silicone disc intraocular lenses].

When oxygen plasma was used for plasma etching it was possible to hydrophilize the surface of silicone intraocular lenses (IOLs) without changing the chemical composition or the properties of deeper layers of the polymer. The modification was characterized by surface analysis. (Electron spectroscopy = XPS, contact angle estimations) and by scanning electron microscope. A cytotoxic influence of the modified surface could be excluded by cell culture experiments in which we evaluated cell spreading, cell morphology, DNA synthesis and protein synthesis. In vivo experiments on rabbits showed that the postoperative foreign body reaction was not significantly influenced by the hydrophilization of the IOL surface. Over the entire follow-up period (12 weeks), there was a reduced tendency to induce posterior synechiae in the group with hydrophilized lenses (P = 0.009). The number of dislocations and the incidence of posterior opacification did not differ significantly; on the other hand there were indications of improved adhesion to the posterior lens capsule of the hydrophilized IOL.

Animals↗
PubMed1990

Motor-evoked potentials in patients with cervical spine disorders.

Measurements of motor-evoked potentials by means of fractionated magnetic stimulation of motor pathways to the upper limbs was performed as part of the clinical assessment in 268 patients with cervical spine disorders. Seventy-two percent of the 127 patients with degenerative changes of the cervical spine, 67% of the 55 patients with rheumatoid arthritis (RA), and 57% of the 51 patients with trauma of the cervical spine showed a pathologic delay of central motor latency (CML). The data suggest that this method has a high sensitivity and therefore is recommended in the diagnosis of cervical spine disorders in patients with suspected compression of neural structures.

Adolescent↗
PubMed1990

The neurologic workup in patients with cervical spine disorders.

Care must be exercised in interpreting the clinical and radiologic findings when assessing patients with cervical spondylosis and involvement of neural structures for surgery. If the clinical picture cannot logically be explained by the radiologic findings, further investigation is indicated to exclude a coexistent disorder. Investigations may include electrophysiologic tests, transcranial magnetic stimulation, cerebrospinal fluid (CSF) analysis, and magnetic resonance imaging (MRI). Only then can the indication for surgical intervention be properly determined.

Aged↗
PubMed1989

[Localization of the gene defect in tuberous sclerosis].

Elucidation of the genetic defect in tuberous sclerosis (TS) awaits a precise chromosomal localization. At present two chromosomal regions, 9q34 and 11q23, are candidates for the site of a TS locus. Family studies using polymorphic DNA markers are carried out in other laboratories and in ours and are expected to disclose the existence of one TS gene that is localized on either chromosome 9 or 11, or the involvement of two genes, one on #9 and one on #11. Early postnatal and potentially prenatal diagnosis by means of DNA analysis may be offered to a family with TS after identification of the gene defect, but also after the identification of very closely linked DNA markers.

Chromosomes, Human, Pair 11↗
PubMed1989

[Problem of the preservation of hearing in acoustic neuroma. Value of the mixed supra petrous and retrosigmoid approach].

The authors described their experience of the possibilities of preservation of hearing on the basis of a series including approximately 180 acoustic neurinomas. Whilst the initial experimental approach involving the use of a sub-occipital approach in seated position was abandoned, in view of the risk of complications inherent to the use of this approach, the authors progressively developed the possibility of the preservation of hearing by a retro-sigmoid approach in horizontal position as described in France by Bremond, Magnand and Garcin, and taken up subsequently by Sterkers. Currently, a retro-sigmoid approach is used combined with a classical supra petral approach which can be used in all cases to assess the tumour at the base of the internal auditory meatus and identify the position of the facial nerve. This surgery by mixed approach can safeguard hearing in small tumours (grades I, II and IIIa) in approximately 75% of cases. Functional hearing should nevertheless be differentiated (approximately one case out of two) in other cases where only residual auditory tissue remains. It is highly likely that improvement in radiological techniques (leading to earlier diagnosis) as well as surgical techniques will lead to the safeguard of hearing in even more cases, and hence the importance of evaluation of these techniques in terms of their relative indication in comparison with the translabyrinthine approach which the authors consider to remain the approach of choice in large tumours (grades IIIb and IV).

Audiometry↗
PubMed1988

Quieting during early infancy: evidence for a developmental change?

The ability to terminate crying (quieting) without intervention was studied from 0 to 18 weeks. Two groups were involved: 11 newborns during the first hour after birth and a longitudinal group of 14 infants seen every 3 weeks from 3 to 18 weeks. Most newborns who cried showed quieting with and without hand-mouth contacting. In the longitudinal group quieting with hand-mouth contacting appeared for the first time at 9 weeks (quieting without hand-mouth contacting being present from 3 weeks). Quieting with hand-mouth contacting was frequently accompanied by hand chewing/sucking. Explanations for the disappearance in quieting with hand-mouth contacting and its reappearance at 9 weeks concern changes in movement and posture. Explanations based on notions of intentionality in quieting were not supported by the data.

Behavior↗
PubMed1988

Response of rheumatoid arthritis to chemotherapy for Hodgkin's disease in a patient with IgA deficiency and overlap connective tissue disease.

A patient with IgA deficiency presented with classical rheumatoid arthritis (RA) and subsequently, features of multiple other connective tissue diseases (CTD). When Hodgkin's disease later developed the patient received combination chemotherapy, which induced remission of both neoplastic and connective tissue diseases. As the RA remained in remission for three years this case may offer insight into a mode of use of cytotoxic agents in CTD.

Adult↗
PubMed1987

Effect of lipopolysaccharides on cultured human endothelial cells. Relationship between tissue factor activity and prostacyclin release.

Exposure to lipopolysaccharides (LPS; 10 micrograms/ml derived from either S. enteritidis or E. coli or to their lipid A moiety alone induced procoagulant activity in cultured human endothelial cells. This exclusively cell-associated activity was identified as tissue factor activity by two criteria: Firstly, the presence of Factor VII was required for its expression and, secondly, clotting was abolished by the addition of the IgG fraction of anti-human tissue factor antibodies. Concomitant analysis of prostacyclin (PGl2) formation by the cells showed a substantial increase in the production of this potent platelet inhibiting substance during exposure to endotoxin. LPS-induced release of PGl2 did not result in refractoriness of the cells to generate new PGl2 as indicated by the retained response to stimulation with 20 microM arachidonic acid. While the release of PGl2 could be inhibited by pretreatment of the cells with 100 microM acetylsalicylic acid (ASA), the induction of tissue factor activity remained unaffected by ASA. In contrast to LPS-free control cultures, ASA did not completely prevent PGl2 formation by human endothelial cells after exposure to LPS suggesting the induction of a cyclooxygenase-independent pathway by LPS.

6-Ketoprostaglandin F1 alpha↗