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Biomedical subjects

M Jansen

Publications and source records attributed to M Jansen.

At least 73 records · Page 4Linked to original sources
PubMed2001

A randomized controlled trial of three years growth hormone and gonadotropin-releasing hormone agonist treatment in children with idiopathic short stature and intrauterine growth retardation.

We assessed the effectiveness and safety of 3 yr combined GH and GnRH agonist (GnRHa) treatment in a randomized controlled study in children with idiopathic short stature (ISS) or intrauterine growth retardation (IUGR). Gonadal suppression, GH reserve, and adrenal development were assessed by hormone measurements in both treated children and controls during the study period. Thirty-six short children, 24 girls (16 ISS/8 IUGR) and 12 boys (8 ISS/4 IUGR), with a height SD score of -2 SD or less in early puberty (girls, B2-3; boys, G2-3), were randomly assigned to treatment (n = 18) with GH (genotropin 4 IU/m(2). day) and GnRHa (triptorelin, 3.75 mg/28 days) or no treatment (n = 18). At the start of the study mean (SD) age was 11.4 (0.56) or 12.2 (1.12) yr whereas bone age was 10.7 (0.87) or 10.9 (0.63) yrs in girls and boys, respectively. During 3 yr of study height SD score for chronological age did not change in both treated children and controls, whereas a decreased rate of bone maturation after treatment was observed [mean (SD) 0.55 (0.21) 'yr'/yr vs. 1.15 (0.37) 'yr'/yr in controls, P < 0.001, girls and boys together]. Height SD score for bone age and predicted adult height increased significantly after 3 yr of treatment; compared with controls the predicted adult height gain was 8.0 cm in girls and 10.4 cm in boys. Furthermore, the ratio between sitting height/height SD score decreased significantly in treated children, whereas body mass index was not influenced by treatment. Puberty was effectively arrested in the treated children, as was confirmed by physical examination and prepubertal testosterone and estradiol levels. GH-dependent hormones including serum insulin-like growth factor I and II, carboxy terminal propeptide of type I collagen, amino terminal propeptide of type III collagen, alkaline phosphatase, and osteocalcin were not different between treated children and controls during the study period. Thus, a GH dose of 4 IU/m(2) seems adequate for stabilization of the GH reserve and growth in these GnRHa-treated children. We conclude that 3 yr treatment with GnRHa was effective in suppressing pubertal development and skeletal maturation, whereas the addition of GH preserved growth velocity during treatment. This resulted in a considerable gain in predicted adult height, without demonstrable side effects. Final height results will provide the definite answer on the effectiveness of this combined treatment.

Adolescent↗
PubMed2000

Studies on the interaction between TWEAK and the death receptor WSL-1/TRAMP (DR3).

WSL-1/TRAMP (DR3) is a member of the tumour necrosis factor (TNF) receptor superfamily which exhibits effects on NF-kappaB activation and apoptosis. TWEAK, a novel TNF-related molecule, has been proposed as the ligand for this receptor. Utilising both human and murine TWEAK ligand, it is shown that TWEAK and WSL-1/TRAMP do not interact in an in vitro binding assay and that TWEAK binds strongly to cells that do not express WSL-1/TRAMP on the cell surface. Biological activity of TWEAK is also observed in these cells. Finally, cells isolated from WSL-1/TRAMP knockout mice are shown to retain their ability to interact with TWEAK. These results suggest that WSL-1/TRAMP is not the major receptor for TWEAK

Animals↗
PubMed2000

Inorganic yellow-red pigments without toxic metals

Inorganic pigments have been utilized by mankind since ancient times, and are still widely used to colour materials exposed to elevated temperatures during processing or application. Indeed, in the case of glasses, glazes and ceramics, there is no alternative to inorganic pigments for colouring. However, most inorganic pigments contain heavy metals or transition metals that can adversely effect the environment and human health if critical levels are exceeded. Cadmium-based pigments in particular are a cause of concern: although the pigments are not toxic due to their very low solubility in water and dilute mineral acids, cadmium itself is toxic and can enter the environment in a bioavailable form through waste-disposal sites and incineration plants. This has led to regulations, based on the precautionary principle, that strongly restrict the use of cadmium pigments. And even though recent assessments have concluded that the risk to humans or the environment might be not as significant as originally feared, a strong demand for inherently safer substitutes remains. Here we demonstrate that solid solutions of the perovskites CaTaO2N and LaTaON2 constitute promising candidates for such substitutes: their brilliance, tinting strength, opacity, dispersability, light-fastness and heat stability rival that of the cadmium pigments, while their colour can be tuned through the desired range, from yellow through orange to deep red, by simple composition adjustments. Because all the constituent elements are harmless, this perovskite-based inorganic pigment system seems a promising replacement that could eliminate one of the sources for cadmium emissions to the environment and some of the remaining concerns about pigment safety.

Journal Article↗
PubMed2000

Direct adsorption of lipoproteins (DALI) from whole blood: first long-term clinical experience with a new LDL-apheresis system for the treatment of familial hypercholesterolaemia.

BACKGROUND: The DALI (direct adsorption of lipoproteins) LDL-apheresis system is a novel device for the removal of lipoproteins from whole blood. METHODS: We report the first long-term treatment experience (16.7 +/- 12.6 months; 57 +/- 43 treatments/patient) using different DALI adsorber sizes (DALI-500, DALI-750, DALI-1000) in seven patients with homozygous (n = 1) and severe heterozygous familial hypercholesterolaemia. For each treatment, 1.6 fold of the calculated blood volume was processed. Treatments were scheduled at weekly or two-weekly intervals. RESULTS: The smallest DALI-500 configuration was unable to achieve sufficient removal of LDL cholesterol, with the adsorber being exhausted already at desorption of 65% of the calculated blood volume. In contrast, both larger adsorber systems effectively removed lipoproteins until the end of treatment. Therefore, the DALI-750 device was used for long-term treatment. LDL cholesterol (mean pretreatment value: 179 +/- 44 mg/dl) was reduced by 73.4 +/- 7.7% and Lp(a) levels (mean pretreatment value: 43 +/- 33 mg/dl) by 69.5 +/- 8.3%. HDL cholesterol (mean pretreatment value: 47 +/- 15 mg/dl) was reduced by 16.3 +/- 8.0% during the treatment. In the long term, LDL cholesterol was reduced by 54.0 +/- 10.5%--from 259 +/- 101 mg/dl to 119 +/- 19 mg/dl. No serious side effects occurred during the treatment. Long-term evaluation of other laboratory parameters showed a reduction in haemoglobin due to treatment-associated blood loss despite frequent iron supplementation. CONCLUSION: Sufficient reductions in LDL cholesterol and Lp(a) were achieved using the DALI-750 system and the treatment was well tolerated. The easy use and short period of 153 +/- 22 minutes required for each treatment are the major advantages of the DALI system as compared to other available LDL-apheresis devices. Potential particle release from the adsorber into the circulation must be ruled out before the system can be introduced in clinical routine.

Adult↗
PubMed2000

Synthesis and SAR of 4-aryl-2-hydroxy-4-oxobut-2-enoic acids and esters and 2-amino-4-aryl-4-oxobut-2-enoic acids and esters: potent inhibitors of kynurenine-3-hydroxylase as potential neuroprotective agents.

The synthesis and structure-activity relationship of a series of 4-aryl-2-hydroxy-4-oxobut-2-enoic acids and esters and 2-amino-4-aryl-4-oxobut-2-enoic acids and esters as potent inhibitors of kynurenine-3-hydroxylase are described. These compounds are the most potent inhibitors of the kynurenine-3-hydroxylase enzyme so far disclosed. Additionally methyl 4-(3-chlorophenyl)-2-hydroxy-4-oxobut-2-enoate (2d), 4-(3-chlorophenyl)-2-hydroxy-4-oxobut-2-enoic acid (3d), methyl 4-(3-fluorophenyl)-2-hydroxy-4-oxobut-2-enoate (2f), and 4-(3-fluorophenyl)-2-hydroxy-4-oxobut-2-enoic acid (3f) prevent the increase in the interferon-gamma-induced synthesis of quinolinic acid in primary cultures of cultured human peripheral blood monocyte-derived macrophages.

Animals↗
PubMed2000

Prospective randomised cross-over comparison of three LDL-apheresis systems in statin pretreated patients with familial hypercholesterolaemia.

Various LDL-apheresis systems have gained wider clinical acceptance in recent years to treat patients with severe familial hypercholesterolaemia, in particular in patients with coronary artery disease. For each single device data on efficacy have been provided, but up to now no comparative analysis including the novel direct adsorption of lipoproteins from whole blood has been reported. This prospectively designed cross-over comparison of three commercially available LDL-apheresis systems (immunoadsorption, IMAL; dextran sulphate adsorption, DSA; direct adsorption of lipoproteins, DALI) was performed in eight patients with homozygous (n = 3) and heterozygous (n = 5) familial hypercholesterolaemia. Removal of atherogenic lipoproteins was highly effective in all systems, for LDL-cholesterol in particular: DSA: - 84.3 +/- 6.2%; IMAL: -82.1 +/- 8.3%; DALI: -76.6 +/- 7.2% (P < 0.05 as compared DALI versus IMAL and DSA). A reduction in Lp(a) of about 63% was achieved by each device. Loss in HDL-cholesterol was highest with IMAL (-21.3 +/- 4.9%, P < 0.05) as compared to the other two treatment modalities. DSA decreased HDL-cholesterol by - 10.4 +/- 6.1% and the DALI system by -12.7 +/- 5.0%. Remarkable differences were found for the removal of fibrinogen (DSA: -29.8 +/- 14.7%, (P < 0.05 versus DALI/IMAL); IMAL: -21.4 +/- 10.1% (P < 0.05 versus DALI); DALI: -14.8 +/- 8.0%). The shortest duration for treatment was achieved by the DALI system (135 +/- 20 min, P < 0.05 versus IMAL (195 +/- 20 min) and DSA (187 +/- 29 min)). No side effects were recorded in the total of 96 treatments performed during the study. Long-term observations have yet to prove whether these differences in efficacy may be of clinical relevance.

Adsorption↗
PubMed2000

Determination of the (Na+) Sternheimer antishielding factor by 23Na NMR spectroscopy on sodium oxide chloride, Na3OCl.

The (Na+) Sternheimer antishielding factor gammainifinity (Na+) was determined by 23Na NMR spectroscopy on sodium oxide-chloride, Na3OCl. The quadrupolar coupling constant of the sodium ion in Na3OCI was determined to QCC = 11.34 MHz, which presents the largest coupling constant of a sodium nucleus observed so far. Applying a simple point charge model, the largest principal value of the electric field gradient at the sodium site was calculated to V(zz) = -6.76762 x 10(20) V/m2. From these values we calculated the (Na+) Sternheimer antishielding factor to gammainifinity (Na+)= -5.36. In sodium oxide, Na2O, we observed an isotropic chemical shift of deltaCS = 55.1 ppm, referenced to 1 M aqueous NaCI (delta = 0 ppm).

Chlorides↗
PubMed2000

Effects of intraperitoneal mitomycin C adsorbed on activated carbon on adhesion formation and mesothelial cells in vitro.

OBJECTIVE: To investigate the incidence of adhesions after intraperitoneal instillation of mitomycin C adsorbed on activated carbon (MMC-CH). DESIGN: Animal and laboratory studies. SETTING: University hospital, Germany. ANIMALS: 90 Sprague-Dawley rats. INTERVENTIONS: Laparotomy, small bowel anastomosis, and intraperitoneal instillation of saline (controls, n = 27), activated carbon alone (n = 24) or MMC-CH (n = 26). Cultures of monolayers of human mesothelial cells. MAIN OUTCOME MEASURES: Measurements of adhesions by planimetry. Toxicity of mitomycin C alone and charcoal alone in mesothelial cell monolayers as reflected by cell proliferation and measurement of lactate dehydrogenase activity. Concentrations of plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) as measures of the fibrinolytic activity of mesothelial cells. RESULTS: Both activated carbon and MMC-CH caused a significant increase of adhesion formation in rats. Activated carbon also reduced the fibrinolytic activity of mesothelial cells, and mitomycin C caused concentration-dependent cytotoxicity in vitro. CONCLUSIONS: Activated carbon combined with high concentrations of mitomycin C may cause intraperitoneal infective complications by increasing the rate of adhesion formation and reducing the fibrinolytic activity of mesothelial cells. We recommend a new absorbable carrier for intraperitoneal chemotherapy.

Animals↗
PubMed2000

Modulated structure of Ag2SnO3 studied by high-resolution electron microscopy

The modulated structure of Ag2SnO3, disilver tin trioxide, was investigated by high-resolution electron microscopy and electron diffraction along four different directions. Electron diffraction showed an incommensurate one-dimensional modulated structure with a modulation wavevector of 1/6.4a*. High-resolution images showed a large number of superstructure domains with the size range 10-100 nm and orientations related by hexagonal rotation. The modulation was determined to be displacements along the c axis of the Ag atoms both in octahedral and linear coordination. An approximate structure model with a commensurate sixfold superstructure, with an orthorhombic cell (P2(1)2(1)2(1), a = 2.922, b = 1.267, c = 0.562 nm), is proposed. Calculated images and electron diffraction patterns, based on this model, agree well with experimental observations.

Journal Article↗
PubMed2000

A novel nonsense mutation of the KAL gene in two brothers with Kallmann syndrome.

Kallmann syndrome (KS), defined by the association of hypogonadotropic hypogonadism and anosmia or hyposmia, can be caused by mutations in the KAL gene on Xp 22.3. This gene encodes an extracellular matrix glycoprotein called anosmin-1, which belongs to the class of cell adhesion molecules. In the absence of a functional KAL protein, migration of both olfactory and gonadotropin-releasing hormone neurons is arrested. A defective anosmin-1 molecule may also play a role in the development of synkinesia and renal agenesis, which are exclusively seen in the X-linked form of KS. We describe the clinical presentation and molecular diagnosis of the defect in two brothers with KS. An X-linked mode of transmission was assumed on the basis of synkinesia and the presence of oligomenorrhoea in the mother. A novel nonsense mutation was found in exon 13 of the KAL gene, encoding the region of the fourth fibronectin type III repeat of anosmin-1, which results in an apparently nonfunctional truncated protein.

Adolescent↗
PubMed2000

Final height after gonadotrophin releasing hormone agonist treatment for central precocious puberty: the Dutch experience.

Final height (FH) data of 96 children (87 girls) treated with GnRH agonist for central precocious puberty were studied. In girls mean FH exceeded initial height prediction by 7.4 (5.7) cm (p < 0.001); FH was significantly lower than target height, but still in the genetic target range. When treatment started < 6 years of age, height gain was significantly higher than when started > 8 years of age. Bone age (BA) and chronological age (CA) at start of treatment, as well as BA advance at cessation of treatment, were the most important variables influencing height gain in multiple regression analysis. BA advance at start of treatment was most important in simple correlation. In girls, GnRHa treatment seems to restore FH into the target range. A younger age and advanced bone age at start of treatment are associated with more height gain from GnRHa treatment.

Body Height↗
PubMed1999

Ceramic fibers for matrix composites in high-temperature engine applications

High-temperature engine applications have been limited by the performance of metal alloys and carbide fiber composites at elevated temperatures. Random inorganic networks composed of silicon, boron, nitrogen, and carbon represent a novel class of ceramics with outstanding durability at elevated temperatures. SiBN(3)C was synthesized by pyrolysis of a preceramic N-methylpolyborosilazane made from the single-source precursor Cl(3)Si-NH-BCl(2). The polymer can be processed to a green fiber by melt-spinning, which then undergoes an intermediate curing step and successive pyrolysis. The ceramic fibers, which are presently produced on a semitechnical scale, combine several desired properties relevant for an application in fiber-reinforced ceramic composites: thermal stability, mechanical strength, high-temperature creep resistivity, low density, and stability against oxidation or molten silicon.

Journal Article↗
PubMed1999

[Prophylactic total thyroidectomy in childhood for multiple endocrine neoplasia type 2A: preliminary results].

OBJECTIVE: Evaluation of prophylactic total thyroidectomy in childhood in case of MEN2A gene carriership. DESIGN: Retrospective. METHOD: Prophylactic thyroidectomy was performed in 14 MEN2A gene carriers (7 boys, 7 girls; median age 9.1 year (range: 4.8-14.7)), in June 1993-July 1997 at the department Pediatric Surgery of the Wilhelmina Children's Hospital in Utrecht, the Netherlands. Median time between genetic investigation and operation was 5.5 months (range: 2-35). Lymph node dissection was not performed. The parathyroids were identified and left untouched as far as possible, autotransplantation was performed twice because of doubt about viability. Outpatient follow-up took place every 3-6 months. RESULTS: One patient (13.4 year) showed macroscopic, the other 13 microscopic multifocal medullary thyroid carcinoma, 11 bilateral and 3 unilateral. In 1 child (6.2 year) neuroinvasive growth existed already. Surgical sections were free of tumour. After the operation temporary hoarseness occurred once, temporary hypocalcaemia three times and permanent hypoparathyroidism twice; after autotransplantation no hypocalcaemia occurred. Median follow-up was 3.2 year (range: 1 month-4.0 year). Mild psychological problems were observed in 4 patients, psychiatric problems in 1. CONCLUSION: Prophylactic total thyroidectomy during the first decade is recommended. Additional lymph node dissection and total parathyroidectomy are unnecessary than. In order to prevent postoperative hypoparathyroidism, autotransplantation of at least one parathyroid is advisable.

Adolescent↗
PubMed1999

Interferon response heterogeneity: activation of a pro-inflammatory response by interferon alpha and beta. A possible basis for diverse responses to interferon beta in MS.

Interferon gamma (IFN-gamma) stimulates the (pro-inflammatory) type II interferon receptor and is known to exacerbate multiple sclerosis (MS). In contrast, IFN-alpha and IFN-beta are ligands for the (anti-inflammatory) type I interferon receptor and are beneficial in some (but not all) patients with MS. Should IFN-beta elicit a type-II-like pro-inflammatory response, the beneficial effects might be attenuated. These studies were undertaken to test this possibility with the use of quinolinic acid (QUIN) formation as a measure of type II receptor activation. In normal human macrophage cultures, IFN-gamma was the most potent stimulus for QUIN formation. Generally, IFN-beta and IFN-alpha were less potent. However, an unexpected inter-patient variability was observed. In some subjects, IFN-alpha was more potent than IFN-beta. In other subjects, IFN-beta was more potent than IFN-alpha. The present data demonstrate an inter-subject variability for QUIN production following exposure to the interferons. MS patients who demonstrate a pro-inflammatory response to IFN-beta (e.g., increased QUIN) may be less likely to benefit from this therapy.

Adult↗
PubMed1999

Value of intravenous cholangiography prior to laparoscopic cholecystectomy.

We performed a retrospective study on 163 patients for evaluation of the benefit of intravenous cholangiography prior to laparoscopic cholecystectomy. Radiographic evaluation of the various areas of the biliary system was classified regarding resolution of anatomic structures: well detailed (excellent), impaired image but reliable interpretation possible (good), insufficient contrast with limited assessment (poor), no reliable judgment possible (insufficient). The common bile duct could be described as "good" in 96.3%, whereas the cystic duct could be described as "good" in only 54.6%. Concrements of the gallbladder were recognized in 72.4%, and common bile duct stones were diagnosed in only two of three patients. A distal junction of the cystic duct was found in nine cases, but there was no influence on the following operative procedure. Only one of two patients with a short cystic duct was identified. We found no improvement after routine use of intravenous cholangiography concerning the evidence of common bile duct stones or the avoidance of lesions of the common bile duct. Hence routine use of intravenous cholangiography prior to laparoscopic cholecystectomy is not justified.

Bile Ducts, Intrahepatic↗
PubMed1999

[Subtotal esophagus resection and stomach tube transposition in laryngectomized patients without loss of esophageal speech].

We report the case of a 71-year-old patient who had a laryngectomy 16 years ago because of a laryngeal carcinoma and achieved voice restoration by esophageal speech. Now a squamous cell carcinoma of the esophagus had been diagnosed and was treated with a subtotal esophagectomy, stomach transposition, and collar anastomosis. Postoperatively, the patient remained esophageal speech without loss of quality.

Aged↗