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Biomedical subjects

A H van Hattum

Publications and source records attributed to A H van Hattum.

11 recordsLinked to original sources
PubMed2002

Induction of breast cancer resistance protein by the camptothecin derivative DX-8951f is associated with minor reduction of antitumour activity.

DX-8951f (exatecan mesylate), a new water-soluble derivative of camptothecin, is currently being evaluated in phase II clinical trials. Resistance may be acquired when treating cancer patients with DX-8951f. Therefore, we selected a subline of the human ovarian cancer cell line A2780 for resistance against DX-8951f to investigate possible mechanisms of resistance. This DX-8951f-resistant subline, designated 2780DX8 (resistance factor=9.3), displayed a typical cross-resistance pattern including compounds, such as topotecan (resistance factor =34), SN-38 (resistance factor =47), mitoxantrone (resistance factor =59) and doxorubicin (resistance factor =2.9), which have previously been associated with the expression of breast cancer resistance protein. 2780DX8 cells did not show changes in the topoisomerase I gene, in topoisomerase I protein levels or catalytic activity. Overexpression of breast cancer resistance protein could be detected, both at the mRNA and protein level, while staining for Pgp, MRP1, or LRP was negative. GF120918, an inhibitor of breast cancer resistance protein, was able to reverse the DX-8951f-induced resistance in 2780DX8 cells. In vivo experiments in well-established 2780DX8 human tumour xenografts demonstrated that the growth inhibition induced by CPT-11 was more affected by breast cancer resistance protein expression than that of DX-8951f. These data indicate for the first time that DX-8951f is able to induce breast cancer resistance protein as a mechanism of resistance. Breast cancer resistance protein, however, results in only minor reduction of antitumour activity of DX-8951f which is an advantage over topotecan and CPT-11/SN-38.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Characterization of human soft-tissue sarcoma xenografts for use in secondary drug screening.

We have established ten transplantable human soft-tissue sarcoma (STS) xenografts grown as subcutaneous tumours in the nude mouse. Nine xenografts originated from patients that needed chemotherapy in the course of their disease. The xenografts were tested for their sensitivity to maximum tolerated doses of five anti-cancer agents. Growth of treated tumours was expressed as a percentage of control tumour growth and a growth inhibition > 75% was measured for doxorubicin in 20% of the STS xenografts, for cyclophosphamide in 30%, for ifosfamide in 20%, for vincristine in 20%, whereas etoposide was not effective in the STS xenografts. In three out of ten STS xenografts MDR1 mRNA was detectable, but this was not related to the resistance against doxorubicin, vincristine or etoposide. Topoisomerase IIalpha mRNA expression levels did not reflect sensitivity to doxorubicin or etoposide. In all STS tissues, however, these levels were lower than topoisomerase IIalpha mRNA in a drug-sensitive human ovarian cancer xenograft. Glutathione concentrations and the activities of glutathione S-transferase, glutathione peroxidase and glutathione reductase were not related to resistance against the alkylating agents or doxorubicin. Of interest, in all STS tissues, glutathione S-transferase pi was the predominant isoenzyme present. In conclusion, chemosensitivity of the STS xenografts reflects clinical response rates in phase II trials on the same compounds in adult STS patients. Relatively low levels of topoisomerase IIalpha mRNA may partly account for intrinsic resistance against, for example, doxorubicin. Additional factors must contribute to moderate responsiveness to alkylating agents.

Animals↗
PubMed1996

Text processing by digital voice recognition.

OBJECTIVE: To evaluate digital voice recognition in free text mode. STUDY DESIGN: A standard medical text (182 words and punctuation marks) was dictated four times each by six people using a commercially available voice recognition system. RESULTS: The time used, including the time needed for making corrections, decreased from a median of 14.5 (6.3-18.8) minutes in the first session to a median of 6.7 (5.1-15.7) in the fourth session. the number of corrections necessary in the last session was a median of 20.5 (15-97)-i.e., 11% of the number of words in the text. All users described working with the system as highly strenuous. Dictating the same text with a dictaphone took median 1.4 (0.9-1.6) minutes and about five minutes of typing and correction time. CONCLUSION: Although the total time was about the same with the two methods, the time for the pathologist increased fourfold when using the voice recognition system. To obtain acceptable input speed, an appropriate template module is essential.

Signal Processing, Computer-Assisted↗
PubMed1992

Further evaluation of quantitative nuclear image features for classification of lung carcinomas.

The usefulness of quantitative nuclear image features (QNI) for the histological classification of lung carcinomas was investigated. As no clear distinction could be established between the distributions of these features for the nuclei of squamous cell, adenocarcinoma, and large cell carcinoma, the attention was restricted to the discrimination between small cell lung carcinoma (SCLC) and non-small cell carcinoma (NSCLC). This discrimination is the crucial one in discussions about the choice of treatment. The differences between SCLC and NSCLC are statistically highly significant for various QNI features. The use of more than one QNI feature hardly raised the discriminatory performance with respect to the distinction between SCLC and NSCLC. Inferences were made about the probability and confidence interval of SCLC for a given QNI feature. It is concluded that in cases of uncertainty or disagreement, nuclear characteristics are useful for the discrimination between SCLC and NSCLC.

Adenocarcinoma↗
PubMed1989

[Diagnosis of laryngeal carcinoma using proton spin resonance tomography].

Seventy-eight patients were investigated by magnetic resonance (MR) imaging using optimal scan parameters and a surface coil. Forty-two patients were also examined by computer tomography (CT). Sixteen patients underwent laryngectomy. MR imaging of cancerous tissue in the larynx, and particularly of non-invaded and invaded cartilages, was examined by comparing MR images with sliced surgical specimens. Pre-operative CT and MRI findings were evaluated by comparing them with postoperative histopathological findings. MR T1-weighted images demonstrate localisation and extent of cancerous tissue. With combined use of T1-weighted and proton-density images MR imaging is superior to CT for showing cartilage invasion. Unfortunately, gross movement artifacts, which resulted in non-diagnostic images, occurred in 16% of the examinations.

Aged↗
PubMed1988

The effect of sampling on quantitative nuclear image features in histologic sections of lung carcinomas.

A feasibility study showed that quantitative nuclear image (QNI) analysis, in which the morphology of the nucleus is described by a number of mathematical parameters, can be used to make the therapeutically and prognostically important distinction between small cell lung carcinoma (SCLC) and non-SCLC, which can be difficult to make with subjective histologic typing. In the present study, the effects of sample size and sample site on the QNI features were investigated. For all sample sites in a given tumor, comparison was made between the histologic classification, the ultrastructural findings and the classification based on the QNI features. Using a running mean, it was found that a sample size of 25 nuclei is sufficiently large. Histologic and quantitative classifications of samples from different sites of the same tumors were in agreement with regard to the separation of SCLC and non-SCLC in 19 of 20 sections. In the case in which disagreement occurred in one section, the ultrastructural findings supported the quantitative classification. These data indicate that sampling from different sites has no essential influence on the QNI classification of lung carcinomas.

Carcinoma, Small Cell↗
PubMed1981

Healing of a superficial lesion in the common bile duct of the rabbit.

By means of a special apparatus a superficial lesion was made in the common bile duct of the rabbit; the healing of the lesion was studied by transmitted light microscopy and scanning electron microscopy. Within a few hours the cells in the epithelial margin became flattened and started to migrate over the bottom of the defect. In most cases the lesion was closed after 16 to 24 hours by epithelial migration. After 24 hours a sharp increase in the mitotic activity occurred, first especially in the crypts, later also in the superficial epithelium. A blood clot on or necrosis of the wound basis seemed to stop the migration of the epithelium. Necrosis of the connective tissue in the central part of the lesion occurred after 24 hours if the lesion was not epithelialized, possibly by the action of bile. In that case the lesion healed by secondary intention. After 2-8 weeks all lesions were healed completely, no strictures being observed.

Animals↗
PubMed1979

A model for the study of epithelial migration in wound healing.

A model is described which enables the detailed study of epithelial regeneration in experimentally produced lesions in the common bile duct of the rabbit. The circular on slightly oval defect of 1 mm diameter produced by a specially developed apparatus has a perfectly smooth base. Epithelial migration in this model has been investigated using light microscopy of transverse sections and scanning electron microscopy of whole preparations. Typical changes in the border cells, characterised by the formation of tapered protusions, can be observed as early as two hours after the lesion has been made. Later the cells in the flattened edge of the moving border also show various types of protrusion which rest on the substratum. Mitotic activity in the surface epithelium and crypts in the surrounding region only increases after closure of the lesion, which usually takes place within 16--24 h.

Animals↗
PubMedDate not supplied

MR imaging of laryngeal cancer.

Forty-four consecutive patients with laryngeal carcinomas presenting at different stages of the disease were investigated by magnetic resonance (MR) imaging. Twelve patients (six with primary lesions and six with recurrent tumors) underwent laryngectomy, and the macro- and microscopic appearance of the slice specimens were correlated with MR imaging. In the remaining patients surgery was not performed, and MR results are compared with the laryngoscopic findings. Cancerous tissue was seen on T1-weighted images as a homogeneous mass of intermediate signal intensity. slightly higher than infrahyoid muscles. The MR examinations failed mainly in patients with tumor recurrence who had undergone previous radiation treatment.

Aged↗