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Biomedical subjects

D Jansen

Publications and source records attributed to D Jansen.

13 recordsLinked to original sources
PubMed2000

Cloning and characterization of a novel Kruppel-associated box family transcriptional repressor that interacts with the retinoblastoma gene product, RB.

The retinoblastoma gene product, RB, seems to function as a key tumor suppressor by repressing the expression of genes activated by members of the E2F family of transcription factors. In order to accomplish this, RB has been proposed to interact with a transcriptional repressor. However, no genuine transcriptional repressors have been identified by virtue of interaction with RB. By using the yeast two-hybrid system, we have identified a novel member of a known family of transcriptional repressors that contain zinc fingers of the Kruppel type and a portable transcriptional repressor motif known as the Kruppel-associated box (KRAB). The mouse and human forms of the novel RB-associated KRAB protein (RBaK) are widely expressed. The amino acid motif that links the KRAB domain and zinc fingers appears to be required for interaction with RB in vitro. Human RBaK ectopically expressed in fibroblasts is an 80-kDa protein that is localized to the nucleus. The expression of either RB or RBaK in 10T1/2 fibroblasts represses the activation of an E2F-dependent promoter and decreases DNA synthesis to a similar degree. However, a mutant form of RBaK that cannot interact with RB in vitro is unable to prevent DNA synthesis. We present a model in which RB physically interacts with the novel transcriptional repressor RBaK to repress E2F-dependent genes and prevent DNA synthesis.

Amino Acid Sequence↗
PubMed2000

Revisiting breast masses with the plastic surgeon: suggestions for biopsy and resection.

Between 250,000 and 500,000 breast mass biopsies are performed each year. This is a common procedure of the breast that should be planned such that maximum treatment is achieved with minimal disfigurement and scarring. Plastic surgery techniques must be used in the choice of biopsy site and planned excision and can result in an improved cosmetic result for the patient. Subareolar masses are resected using a radial elliptical incision. Lateral and medial masses are resected using the Wise pattern reduction mammaplasty whereas the vertical mammaplasty is used for lesions of the central inferior breast and inframammary fold. Awareness of these basic reconstructive principles by the general surgeon can minimize disfigurement and facilitate future reconstruction by the plastic surgeon so that both cure and cosmesis can be achieved.

Biopsy↗
PubMed1999

Marked impairment of protein tyrosine phosphatase 1B activity in adipose tissue of obese subjects with and without type 2 diabetes mellitus.

Protein tyrosine phosphatases (PTPs) are required for the dephosphorylation of the insulin receptor (IR) and its initial cellular substrates, and it has recently been reported that PTP-1B may play a role in the pathogenesis of insulin resistance in obesity and type 2 diabetes mellitus (DM). We therefore determined the amount and activity of PTP-1B in abdominal adipose tissue obtained from lean nondiabetic subjects (lean control (LC)), obese nondiabetic subjects (obese control (OC)), and subjects with both type 2 DM (DM2) and obesity (obese diabetic (OD)). PTP-1B protein levels were 3-fold higher in OC than in LC (1444 +/- 195 U vs 500 +/- 146 U (mean +/- SEM), P < .015), while OD exhibited a 5.5-fold increase (2728 +/- 286 U, P < .01). PTP activity was assayed by measuring the dephosphorylating activity toward a phosphorus 32-labeled synthetic dodecapeptide. In contrast to the increased PTP-1B protein levels, PTP-1B activity per unit of PTP-1B protein was markedly reduced, by 71% and 88% in OC and OD, respectively. Non-PTP-1B tyrosine phosphatase activity was comparable in all three groups. Similar results were obtained when PTP-1B activity was measured against intact human IR. A significant correlation was found between body mass index (BMI) and PTP-1B level (r = 0.672, P < .02), whereas BMI and PTP-1B activity per unit of PTP-1B showed a strong inverse correlation (r = -0.801, P < .002). These data suggest that the insulin resistance of obesity and DM2 is characterized by the increased expression of a catalytically impaired PTP-1B in adipose tissue and that impaired PTP-1B activity may be pathogenic for insulin resistance in these conditions.

Adipose Tissue↗
PubMed1998

Type VI collagen is associated with microfibrils and oxytalan fibers in the extracellular matrix of periodontium, mesenterium and periosteum.

Type VI collagen was immunolocalized in several soft connective tissues at the light and electron microscopic level. Positive labeling was found in all tissues examined, periodontal ligament, gingiva, mesenterium and periosteum. The labeled structures could be divided into 2 categories: microfibrils intermingling with collagen fibrils, and those that formed bundles (oxytalan fibres and elastin-associated microfibrils). Control sections incubated with antibody preabsorbed to purified type VI collagen, or with non-immune antibody, proved to be negative. Our observations indicate that the structural organization of type VI collagen varies from small microfibrillar structures associated with the collagen and elastin fibre systems to highly ordered parallel arrays of oxytalan bundles.

Animals↗
PubMed1996

[The monorail system--bone segment transport over unreamed interlocking nails].

A treatment protocol is demonstrated, consisting of an osteotomy, either proximal or distal, of the bone defect with subsequent segmental transport via an anteromedially (tibia) or laterally (femur) mounted AO external fixation over an unreamed interlocking nail (monorail system). Twenty patients were treated by this method with indications as follows: 13 had a segmental bone defect of the tibia, 3 of the femur. Three patients showed post-traumatic and postinfectious leg-length discrepancies and one was treated for hypertrophic non-union of the femur. Defect distance varied between 5 and 18.5 cm and average time for transport was 19,42 days/ cm for the tibial shaft, 15,93 days/cm for the femur. Two patients developed deep infection, which required change of treatment, removing the monorail system and application of an Ilizarov apparatus. Despite complications using the monorail system, all patients healed and no amputations were required. The monorail system can be used as an alternative to the Ilizarov method under certain criteria of patient selection; these criteria are shown by an algorithm for segmental bone defects without infection, respecting the soft-tissue status with or without neurovascular compromise.

Adolescent↗
PubMed1994

The impact of a clinical nurse's role on CVC infections and bacteremia: a two year comparative, retrospective study.

The purpose of this study was to compare the central venous catheter (CVC) tip infection rate among patients in general wards for the 12 months prior to, and during, the appointment of a TPN clinical nurse at the 500 bed Gold Coast Hospital, Southport, Queensland. These data could then be utilized to assess the benefits of a TPN clinical nurse dedicated to the care of CVCs on the central line infection rate. A comparative retrospective study of 542 CVC tips cultured and analysis of positive blood cultures growing the same organisms was carried out over a two year period. The incidence of CVC tip infections over the study period showed a significant reduction from 37% in the year prior to the appointment of the TPN clinical nurse, to 16% during the first year of appointment. The incidence of bacteremia from all positive CVC tips cultured also decreased from 7.1% to 3.3% respectively.

Bacteremia↗
PubMed1991

Laser thermal ablation.

Continuous wave and pulsed laser ablation of tissue is described as an explosive event. A subsurface temperature maximum and superheated tissue produce high pressures that eject fragments from the tissue. Decreased water content due to dehydration and vaporization decreases thermal conductivity which reduces heat conduction. Also, a decrease in water content dramatically alters the local rate of heat generation of laser radiation above 1.3 microns since water is the primary absorber. In contrast, at UV wavelengths protein and DNA are the primary absorbers so destruction of tissue bonds is due to direct absorption of the laser light rather than heat transfer from water.

Animals↗
PubMedDate not supplied

Homosexuality in Dutch instruction books for youths.

The information on homosexuality was analyzed in the 71 sex-instruction books for youths published in The Netherlands between 1945 and 1982. Within this period, substantial shifts occurred toward a more tolerant attitude regarding homosexuality. Still, quite a few things can be said against the modern instruction books and the authors urge an unremitting critical attitude in evaluating these books.

Adolescent↗