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Biomedical subjects

M A den Bakker

Publications and source records attributed to M A den Bakker.

At least 19 recordsLinked to original sources
PubMed2007

Molecular analysis of human endometrium: short-term tibolone signaling differs significantly from estrogen and estrogen + progestagen signaling.

Tibolone, a tissue-selective compound with a combination of estrogenic, progestagenic, and androgenic properties, is used as an alternative for estrogen or estrogen plus progesterone hormone therapy for the treatment of symptoms associated with menopause and osteoporosis. The current study compares the endometrial gene expression profiles after short-term (21 days) treatment with tibolone to the profiles after treatment with estradiol-only (E(2)) and E(2) + medroxyprogesterone acetate (E(2) + MPA) in healthy postmenopausal women undergoing hysterectomy for endometrial prolapse. The impact of E(2) treatment on endometrial gene expression (799 genes) was much higher than the effect of tibolone (173 genes) or E(2) + MPA treatment (174 genes). Furthermore, endometrial gene expression profiles after tibolone treatment show a weak similarity to the profiles after E(2) treatment (overlap 72 genes) and even less profile similarity to E(2) + MPA treatment (overlap 17 genes). Interestingly, 95 tibolone-specific genes were identified. Translation of profile similarity into biological processes and pathways showed that ER-mediated downstream processes, such as cell cycle and cell proliferation, are not affected by E2 + MPA, slightly by tibolone, but are significantly affected by E(2). In conclusion, tibolone treatment results in a tibolone-specific gene expression profile in the human endometrium, which shares only limited resemblance to E(2) and even less resemblance to E2 + MPA induced profiles.

Cluster Analysis↗
PubMed2006

A critical appraisal of prognostic and predictive factors for common lung cancers.

The outlook for patients with lung cancer remains poor despite advances in the understanding of the pathology and biology of this disease. To optimize treatment protocols prognostic data are essential. The current era with molecular research on mRNA expression analysis and proteomics will lead to a plethora of new molecular markers, which are likely to be correlated, at least in part, with each other and with disease activity, progression and survival. However, although the number of prognostic factors analysed in published systematic reviews on lung cancer is large, the scope of these factors in individual studies is often narrow. In daily practice prognostic factors other than general TNM staging are not implemented. To assess the efficacy of new prognostic factors for the management of individual patients with non-small cell lung cancer, studies with clinically relevant modelling are required. In this review arguments are provided to use a model combining radiological and histopathological growth rate, histopathological diagnosis and molecular characteristics as markers for metastatic capacity, tumour volume doubling time and expected response to targeted therapy. This may reveal time-related predictive information useful for treatment guidance of the individual patient.

Biomarkers, Tumor↗
PubMed2006

"Cutaneous-type" angiosarcoma arising in a mature cystic teratoma of the ovary.

Benign and malignant somatic tumours arising in mature cystic teratomas of the ovary are a rare but recognised phenomenon. Squamous cell carcinoma is the most common somatic malignancy arising in ovarian teratomas, although many other types of tumour have been described. An angiosarcoma with "cutaneous" type typical features arising in a dermoid cyst of the ovary is reported. Vascular tumours have only rarely been described as secondary somatic tumours in ovarian teratomas. The diagnostic features and complications of such tumours are described.

Adult↗
PubMed2006

Extra-axial chordoma.

A chordoma which occurs as a primary tumour outside the axial skeleton is known as an extra-axial chordoma, parachordoma or chordoma periphericum. It is extremely rare and therefore survival, recurrence and the rates of metastasis are not known. Whilst few recurrences have been described, the extra-axial chordoma has the potential for late recurrence at up to 12 years. Metastases are even less frequent. We report the case of a 56-year-old woman who developed an extra-axial chordoma of the right thoracic wall in close relationship with the tenth rib. The tumour was completely removed and the prognosis is excellent.

Chordoma↗
PubMed2004

Fatal outcome of a hypersensitivity reaction to paclitaxel: a critical review of premedication regimens.

Hypersensitivity reactions (HSRs) to paclitaxel are frequently encountered in patients receiving this antitumour drug. Administration of histamine H1- and H2-receptor antagonists and corticosteroids has been shown to reduce significantly the risk of developing an HSR in patients receiving taxanes. In this case report, we describe the fatal outcome of an HSR in a patient receiving paclitaxel despite short-course premedication. The level of evidence supporting the short-course i.v. premedication schedule is challenged, as it is not compatible with the pharmacokinetic properties of dexamethasone.

Anti-Inflammatory Agents↗
PubMed2003

CD31 staining in epithelioid sarcoma.

We report an unusual case of epithelioid sarcoma. The tumour occurred in the finger of a 27-year-old female. The clinical history, histology and the electron microscopy of the lesion were typical for epithelioid sarcoma. However, immunohistochemical analysis showed strong membranous CD31 staining, a finding hitherto not described. All other robust vascular markers, including factor-VIII-related antigen (FVIIIrag) were negative. The findings were compared with the available literature data, leading us to conclude that there is insufficient evidence for endothelial derivation of epithelioid sarcoma, but in the differential diagnosis with vascular tumours CD31 may stain and to rule out angiosarcoma FVIIIrag is a useful antibody.

Adult↗
PubMed2003

Lack of c-kit exon 11 activating mutations in c-KIT/CD117-positive SCLC tumour specimens.

Previous studies have shown that STI571, a selective tyrosine kinase inhibitor of c-KIT, is highly effective in c-KIT/CD117-positive gastrointestinal stromal tumours (GIST), especially those that have activating mutations in the c-kit exon 11 that encodes the juxtamembrane (JM) domain of the c-KIT oncoprotein. We examined the prevalence of activating exon 11 c-kit mutations in 26 small-cell lung cancer (SCLC) cases in order to explore whether this disease is also a potential target for treatment with STI571. Expression of c-KIT, estimated by immunohistochemistry, was demonstrated in 14 out of 22 SCLC samples (64%); nine samples showed moderate to strong staining (41%), five samples were weakly positive (23%), whereas eight samples (36%) were negative for CD117. Next, we examined the mutational status of exon 11 of the c-kit gene, by single-stranded conformational polymorphism (SSCP) and sequencing in all of the cKIT/CD117-positive tumours. However, no activating mutations in the c-kit exon 11 were found by either technique. Apparently, c-KIT oncoprotein expression in SCLC was not correlated with activating mutations in c-kit exon 11. In analogy to GISTs, our results could imply that SCLC patients would not benefit from treatment with STI571.

Carcinoma, Small Cell↗
PubMed2003

Microsatellite instability in a pleomorphic rhabdomyosarcoma in a patient with hereditary non-polyposis colorectal cancer.

AIMS: To describe the rare occurrence of a pleomorphic sarcoma with microsatellite instability in a patient with hereditary non-polyposis colorectal cancer (HNPCC). METHODS AND RESULTS: A soft tissue tumour was removed from the upper leg of a patient who had previously been shown to harbour a germ-line MSH-2 mutation. The tumour was analysed with immunohistochemistry and molecular methods. The morphology and immunohistochemical findings were in keeping with a pleomorphic rhabdomyosarcoma. Microsatellite instability was documented in the tumour with molecular methods and in addition loss of MSH-2 expression in the tumour cells was confirmed by immunohistochemistry. CONCLUSIONS: Although sarcomas do not form part of the HNPCC diagnostic criteria, they may occur in this mismatch repair syndrome and, moreover, may well be caused by the underlying genetic defect.

Adult↗
PubMed2002

Malignant mesenchymoma of the uterus, arising in a leiomyoma.

AIMS: To document and find evidence for the rare occurrence of malignant progression of a benign uterine leiomyoma with divergent mesenchymal differentiation. In a 54-year-old female a large pedunculated tumour was encountered which had suddenly increased in size and had apparently arisen at the site of a subserosal uterine leiomyoma first described 19 years earlier. The tumour seemed histologically diverse in its composition. The possibility of malignant progression of the benign leiomyoma with divergent mesenchymal differentiation was entertained. METHODS AND RESULTS: In the resected tumour, smooth muscle, osseous and adipose components were identified and these were assessed using recognized histological criteria of malignancy. In addition to a benign smooth muscle component, malignant leiomyosarcomatous tissue was seen in addition to a malignant osseous component and a malignant adipose component. The tumour thus met the criteria of a malignant mesenchymoma. The relationship of the different components of the tumour was analysed by immunohistochemistry and with molecular loss of heterozygosity (LOH) analysis. In the osseous and leiomyosarcomatous components a similar LOH pattern was observed. The adipose component showed a distinct LOH pattern. Retention of smooth muscle differentiation in the osseous component was demonstrated by desmin immunostaining. CONCLUSION: Malignant transformation of benign uterine leiomyoma may rarely occur. Mesenchymal stem cells underlying these tumours may show divergent mesenchymal differentiation.

Adipose Tissue↗
PubMed2002

Non-sentinel lymph node involvement in patients with breast cancer and sentinel node micrometastasis; too early to abandon axillary clearance.

AIMS: It has been suggested that patients with T1-2 breast tumours and sentinel node (SLN) micrometastases, defined as foci of tumour cells smaller than 2 mm, may be spared completion axillary lymph node dissection because of the low incidence of further metastatic disease. To gain insight into the extent of non-sentinel lymph node (n-SLN) involvement, SLNs and complementary axillary clearance specimens in patients with SLN micrometastases were examined. METHODS: A set of 32 patients with SLN micrometastases was selected on the basis of pathology reports and review of SLNs. Five hundred and thirteen n-SLNs from the axillary clearance specimens were serially sectioned and analysed by means of immunohistochemistry for metastatic disease. Lymph node metastases were grouped as macrometastases (> 2 mm), and micrometastases (< 2 mm), and further subdivided as isolated tumour cells (ITCs) or clusters. RESULTS: In 11 of 32 patients, one or more n-SLN was involved. Grade 3 tumours and tumours > 2 cm (T2-3 v T1) were significantly associated with n-SLN micrometastases as clusters (grade: odds ratio (OR), 8.3; 95% confidence interval (CI), 1.4 to 50.0; size: T2-3 tumours v T1: OR, 15; 95% CI, 2.18 to 103.0). However, no subgroup of tumours with regard to size and grade was identified that did not have n-SLN metastases. CONCLUSIONS: In patients with breast cancer and SLN micrometastases, n-SLN involvement is relatively common. The incidence of metastatic clusters in n-SLN is greatly increased in patients with T2-3 tumours and grade 3 tumours. Therefore, axillary lymph node dissection is especially warranted in these patients. However, because n-SLN metastases also occur in T1 and low grade tumours, even these should be subjected to routine axillary dissection to achieve local control.

Axilla↗
PubMed2000

Evidence for a cytoskeleton attachment domain at the N-terminus of the NF2 protein.

Neurofibromatosis type 2 is a hereditary cancer syndrome characterized by the development of bilateral vestibular schwannomas. Underlying the disease are inactivating mutations of the NF2 tumor suppressor gene, located on chromosome 22, encoding a 595-amino-acid protein. The NF2 protein, also known as merlin or schwannomin, is reported to act as a membrane-cytoskeleton linking protein. This assumption is based on the homology of the NF2 protein to a group of band 4.1-related proteins, ezrin, radixin, and moesin. The cytoskeletal association of the NF2 protein has in part been confirmed by its ability to resist extraction from cells by nonionic detergents. We performed detergent extraction on COS cells transfected with NF2 cDNA constructs. The extracts were analyzed by Western blotting and immunofluorescent staining with monoclonal anti-NF2 antibodies. The results provide evidence for a high-affinity cytoskeleton attachment domain at amino acids 29-131 and a putative lower affinity domain between amino acids 321 and 470.

Animals↗
PubMed1999

Expression of the neurofibromatosis type 2 gene in human tissues.

The neurofibromatosis Type 2 tumor suppressor gene is implicated in the hereditary tumor syndrome NF2, hallmarked by bilateral vestibular schwannomas, meningiomas, and ocular non-neoplastic features. The gene product has characteristics of a membrane cytoskeleton-linking protein but the mechanism of tumor suppression by the NF2 protein remains to be elucidated. The NF2 gene is widely expressed in mouse and rat tissues. In humans, most of the expression data have accumulated through Northern blot analysis, RT-PCR and, more recently, Western blot analysis, providing information on whole tissues and organs rather than on specific cell types. We report here an extensive survey of NF2 gene expression in human tissues using a combination of mRNA in situ hybridization (mRNA ISH) and immunohistochemistry (IH) with a panel of monoclonal antibodies (MAbs) supplemented by tissue immunoprecipitation experiments with affinity-purified polyclonal antibodies. Expression was observed in many different cell types, most of which appear functionally normal in individuals affected by NF2. Surprisingly, expression could not be consistently documented in Schwann cells and arachnoidal cells by IH or by mRNA ISH in formalin-fixed tissue. However, consistent immunostaining of Schwann cells was seen in frozen sections. (J Histochem Cytochem 47:1471-1479, 1999)

Animals↗
PubMed1998

Subtotal liver calcification due to epithelioid hemangioendothelioma.

A hepatic epithelioid hemangioendothelioma leading to almost complete calcification of the right and left liver lobes in a 75-year-old female is reported. Over a period of 16 years the liver progressively calcified, but its function remained normal by compensatory hypertrophy of the caudate lobe. Multiple partially calcified metastases were present in the lungs, peripancreatic region and along the left principal bronchus. Extreme liver calcification has only rarely been reported. The case presented here reflected slow tumor growth and subsequent long disease course. The vascular nature of the tumor was confirmed by immunohistochemical and ultrastructural analysis.

Aged↗
PubMed1998

A G-->A transition creates a branch point sequence and activation of a cryptic exon, resulting in the hereditary disorder neurofibromatosis 2.

We describe a G-->A transition within intron 5 of the NF2 gene. This mutation creates a consensus splice branch point sequence. To our knowledge this is the first report of a mutation that creates a functional branch point sequence in a human hereditary disorder. The new branch point sequence is located 18 bp upstream of a consensus splice acceptor site. A consensus splice donor site is found 106 bp 3' of the acceptor site. Asa consequence the G-->A transition results in an alternatively spliced mRNA containing an additional exon 5a of 106 bp derived from intron sequences. We cloned the mutant cDNA and show that due to an in-frame stop codon the cDNA codes for a truncated NF2 protein. The mutation was observed in three affected members of an NF2 family. In a tumour of one of the family members both alternatively spliced and wild-type mRNA were found, although the wild-type allele of the gene is absent due to an interstitial deletion on chromosome 22. We also show that immunoprecipitations reveal the presence of full-length wild-type NF2 protein in the tumour lysate. These data support the hypothesis that some degree of normal splicing of the mutant precursor RNA is taking place. It is therefore likely that this residual activity of the mutant allele explains the relatively mild phenotype in the family. These data also indicate that complete inactivation of the gene is not required for tumour formation.

Adenine↗
PubMed1997

Rupture of a hepatic artery aneurysm caused by Wegener's granulomatosis.

Among vasculitis syndromes Wegener's granulomatosis (WG) is characterized by involvement of the upper and lower airways and kidneys. The associated vasculitis involves small and medium sized arteries and veins. Aneurysm formation and a segmental pattern of involvement of larger arteries is not typically seen in WG--a presentation more in keeping with polyarteritis nodosa. We report on a patient hospitalized with classical manifestations of WG who died suddenly of hypovolemic shock caused by intraperitoneal hemorrhage resulting from rupture of a hepatic artery aneurysm. The aneurysm was caused by involvement of the hepatic artery in the disease process. To our knowledge aneurysmatic dilatation of the hepatic artery due to WG has not been previously described. This case illustrates an unusual disease course in WG and the overlap which exists in classical vasculitis syndromes.

Aneurysm, Ruptured↗