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D Obradovic

Publications and source records attributed to D Obradovic.

11 recordsLinked to original sources
PubMed1998

Information maximization and independent component analysis; is there a difference?

This article provides a detailed and rigorous analysis of the two commonly used methods for redundancy reduction: linear independent component analysis (ICA) posed as a direct minimization of a suitably chosen redundancy measure and information maximization (InfoMax) of a continuous stochastic signal transmitted through an appropriate nonlinear network. The article shows analytically that ICA based on the Kullback-Leibler information as a redundancy measure and InfoMax lead to the same solution if the parameterization of the output nonlinear functions in the latter method is sufficiently rich. Furthermore, this work discusses the alternative redundancy measures not based on the Kullback-Leibler information distance. The practical issues of applying ICA and InfoMax are also discussed and illustrated on the problem of extracting statistically independent factors from a linear, pixel-by-pixel mixture of images.

Algorithms↗
PubMed1995

Physical mapping of sequences homologous to an endogenous retrovirus LTR on human chromosome 19.

The human genome contains multiple copies of sequences related to the HERV-K family of endogenous retroviruses, homologous to the B-type mouse mammary tumour virus. A DNA fragment closely resembling an HERV-K long tandem repeat (LTR) was detected in a library of hncDNA clones enriched for sequences from human chromosome 19. Sites showing homology to the sequence of this fragment have been identified on human chromosome 19 by hybridization to previously mapped chromosome 19 cosmids. Thus the distribution of LTR sequences on a specific human chromosome has been mapped for the first time. We estimate the total number of such sites on human chromosome 19 to be at least 110. Many of these sites are located in the vicinity of known genes. The precise localizations (to specific cosmids) of LTR-homologous sequences on chromosome 19 can serve as a reference source and will automatically provide further insight into LTR-gene relationships as new genes are mapped onto the chromosome.

Animals↗
PubMed1993

Fine-needle aspiration in the diagnosis of head and neck growths: the pitfalls of false-positive diagnosis.

The results of fine-needle aspiration cytology (FNA) performed on 235 patients with head and neck growths were analyzed. The accuracy rate was 83%. The FNA was nondiagnostic in 9%, false negative in 7% and false positive in 1% of the cases. These results are similar to those in other centers. Due to false-negative diagnoses, FNA rarely allows the making of a major clinical decision. False-positive diagnoses oblige the clinician to perform several investigations to assess the diagnosis of nonmalignancy and to reassure the patient. Thus, in our opinion, FNA is helpful for the diagnosis of head and neck growths in some rare situations only.

Biopsy, Needle↗
PubMed1990

Fine-needle aspiration in the diagnosis of head and neck growths: is it necessary?

The results of fine-needle aspiration cytology performed on 150 patients at the Geneva Clinic of Otolaryngology were analyzed. The accuracy rate was 80%. The study was nondiagnostic in 10% of the cases and falsely negative in another 10%. These results are similar to those in other centers. Nevertheless, several recent reports attest to the accuracy of fine-needle aspirations cytology, and in some clinics it is now part of the initial workup of every patient with a growth in the head and neck. On the basis of our own retrospective analysis, we believe fine-needle aspiration is a useful study only in patients with a previously treated malignancy and who have a new lump in the neck suspected to be a recurrence.

Biopsy, Needle↗
PubMed1988

Cancer of the cervix stage Ib and IIa: survival related to treatment and histopathological risk factors.

Forty-five patients with carcinoma of the cervix stage Ib or IIa underwent primary radical surgery. The patho-histological examination of the surgical specimens showed, that pelvic lymph node metastases, tumour volume, depth of tumour invasion, lymphatic or vascular permeation and parametrial involvement were significant bad prognostic factors. The histological types of squamous cell carcinomas and local lymphoplasmocytic stromal reaction to the tumour had no statistical prognostic significance. A simple and objective method of assessing tumour volume is described. A 5-year actuarial survival rate for patients with metastatic pelvic lymph nodes (33% of the patients in this study) treated by surgery and additional postoperative external whole pelvis radiotherapy was 55%. This is significantly lower than the 86% 5-year actuarial survival rate of patients without pelvic lymph node metastases treated by surgery alone (P less than 0.05). The postoperative radiotherapy of carcinoma of the cervix with bad prognostic factors including pelvic lymph node metastases seems to improve local tumour control and perhaps survival in a subgroup of node negative tumours presenting other histopathological risk factors.

Adult↗
PubMed1987

Surgery as part of a combined modality approach for inflammatory breast carcinoma.

From November 1977 to February 1984 21 patients with inflammatory breast carcinoma (IBC) were treated in a prospective, nonrandomized study with initial chemotherapy, consisting of a combination of chlorambucil, methotrexate, 5-fluorouracil, and doxorubicin. Modified radical mastectomy was performed after three courses of chemotherapy followed by another six courses of the same chemotherapy. Locoregional radiotherapy concluded the treatment program. All patients responded clinically to the initial chemotherapy. Modified radical mastectomy provided a direct histologic control of the effectiveness of the treatment and, in case of tumor persistence, allowed cytoreduction. No scarring problems were observed and postoperative chemotherapy could be administered without any delay. Radiotherapy was decisive for locoregional tumor control which was obtained in all patients who were treated strictly according to the protocol. Dermal lymphatic involvement represented in this series of clinical inflammatory breast carcinoma no pejorative feature and positive hormone receptors failed to be of predictive value for response to treatment. Considerably variable tumor persistence after initial chemotherapy and the results relative to local tumor control advocate surgery as part of a combined modality approach for inflammatory breast carcinoma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Early ultrastructural changes in RU-486-exposed decidua.

An antiprogesterone (RU-486) was administered to women undergoing voluntary interruption of pregnancy. Five patients received 100 mg 12 h before surgical interruption, 5 others received 100 mg twice, 24 and 12 h before interruption, respectively, and another 5 received no drug at all and served as controls. Placentas and deciduae were examined morphologically with the light microscope and by electron microscopy. No specific lesions were detected in placental tissue. With conventional histology, the deciduae showed various degrees of interstitial edema and necrosis, changes which did not enable a distinction between treated cases and controls, although stromal disintegration tended to be more marked in RU-486-treated patients. At the ultrastructural level, the endothelium of decidual capillaries showed striking hyperplasia of the endoplasmic reticulum. Morphometric evaluation showed a statistically significant difference between RU-486-treated patients (2 X 100 mg) and controls. A possible link between these morphological changes and the induction of prostaglandin synthesis by the antiprogesterone is suggested. However, the full significance of the observed lesions remains uncertain and does not allow definite conclusions concerning the abortifacient effect of RU-486.

Capillaries↗
PubMed1982

Endometrial and plasma concentrations of pregnancy-associated plasma protein-A (PAPP-A).

Pregnancy-associated plasma protein-A (PAPP-A), oestradiol and progesterone levels have been measured by radioimmunoassay in plasma and in endometrial homogenates of 20 women undergoing hysterectomy. Results were grouped according to the histological stages of the endometrium. In plasma, oestradiol and progesterone concentrations changed from proliferative to secretory stages in the well-established pattern of the menstrual cycle, but PAPP-A levels did not change. In endometrium, oestradiol levels were high during the proliferative stage and low in inactive and secretory endometrium. Endometrial PAPP-A and progesterone concentrations increased from inactive to secretory stages, but only the increase in PAPP-A was statistically significant. A positive correlation observed between endometrial PAPP-A concentrations and plasma oestradiol/progesterone ratio suggests a possible hormonal control for the presence of PAPP-A in the uterus.

Adult↗
PubMed1979

[Prospective study of digestive tumor detection by endoscopy: a comparison of brush cytology and histology].

The diagnostic accuracy of endoscopic appearance, histology and brush cytology has been compared in a prospective study of 192 cases involving esogastric lesions. Macroscopic diagnosis of malignancy was more frequent in benign lesions (23/145) than in true malignancies (21/42). Histology was positive in 29/36 tumors and cytology in 23/36. In cytology there were no false negatives in esophageal tumors, but there were 52% false negatives in gastric tumors and 66% in carcinoma in situ. The combination of the 2 methods resulted in a correct diagnosis in 86% of the tumors in this study.

Biopsy↗