Search PubMed⌕ Search

Biomedical subjects

E Kahn

Publications and source records attributed to E Kahn.

At least 55 records · Page 3Linked to original sources
PubMed1996

Spectral and dynamic confocal fluorescence characterization of cytogenetic preparations.

Investigations were performed on fluorescent in situ hybridization (FISH) preparations to examine whether factor analysis of medical image sequences (FAMIS) can be used to isolate fluorescent probes by means of their spectral and/or extinction dynamic emission properties. FISH is used to track down chromosomes of interest in cell nuclei and mitoses. Cytogenetic techniques producing flat preparations of whole cells were assumed to preserve the probes' access to their targets. To isolate the result of hybridization in the human nuclear interphase, we used a confocal microscope. Labelling of the targets by the probes (sequences labelled by FITC and TRITC) in the nuclei stained by propidium iodide was used as a biological model. We used two methods to isolate the component parts of the model: multispectral analysis and dynamic studies. In the case of multispectral analysis, the investigation was performed on 2D and 3D sequences of 28 images obtained on a single photomultiplier (PM) detector of the confocal microscope by selection of emission through 10-nm interference filters in the range of 500-780 nm and by z-displacement in each filter setting. In the case of dynamic studies, the investigation was performed on sequences of 30-70 images obtained on the same detector by single or average integrated acquisition of 10-30 scans. Confocal scanning yields images with constant excitation time. These images were investigated by FAMIS and the results revealed that the spectra and kinetics as factors, and factor images corresponded to FITC and TRITC stained targets, as well as to propidium iodide stained interphase. In conclusion, we would verify that targets were isolated through the spectrum of the fluorescent probes and could be distinguished from the propidium iodide used to stain the nuclei. It was also possible to distinguish them from the propidium iodide by taking into account differences in photobleaching of the different fluorochromes. The study leads us to process displacements by registration methods prior to factor analysis to improve the results.

Fluorescein-5-isothiocyanate↗
PubMed1995

Pancreatic disorders in pediatric acquired immune deficiency syndrome.

Acute pancreatitis, reported in 17% of pediatric patients with acquired immune deficiency syndrome (AIDS), is said to have a poor prognosis. We describe the pancreatic changes observed at autopsy from 71 children with human immunodeficiency virus (HIV) infection and document their nature, extent, and clinical relevance. The median age at autopsy of the children was 17 months (range, 2 months to 19 years); 38 were boys and 33 were girls. Parental intravenous drug use was the most frequent risk factor for AIDS, followed by blood transfusions. Respiratory failure and sepsis constituted the predominant causes of death. Nonspecific changes, such as edema, inflammation, fibrosis, inspissated material in acini and ducts, and enlarged Langerhans' islet predominated. Acute and chronic pancreatitis were mild except in one instance of a fatal acute probably dideoxyinosine-associated pancreatitis. Pancreatic involvement by opportunistic infections, such as cytomegalovirus (CMV), Mycobacterium avium intracellulare (MAI), and Candida, was focal and rare despite the high prevalence of these infections at autopsy. Focal lymphoplasmacytic infiltration and vascular calcifications were also observed. We conclude that pancreatic changes were frequently noted at autopsy in children with AIDS. They were usually mild, reflected systemic disease states, and were usually not life threatening. The incidence of opportunistic infections of the pancreas was low.

AIDS-Related Opportunistic Infections↗
PubMed1995

A fractal approach to the segmentation of microcalcifications in digital mammograms.

This paper presents a computerized method for the automated segmentation of individual microcalcifications in a region of interest (ROI) known to contain a cluster in digital mammograms. Mammographic parenchyma caj be accurately modeled with the fractal approach, but not areas with microcalcifications. The digitized image is divided into 16 x 16-pixel overlapping windows and those accurately modeled by the fractal model are eliminated. The next steps include local thresholding of the ROIs using an iterative method, the elimination of some of the artifacts and identification of the clustered microcalcifications using a clustering algorithm. The evaluation was performed on 81 simulated clusters superimposed on normal mammographic backgrounds and on a representative database of 408 real mammograms. Microcalcification locations were identified by two radiologists independently. These locations were compared to those found by the computer algorithm. An average of 59% of the simulated microcalcifications and 69% of the microcalcifications common to both radiologists were detected. The algorithm described provides a fully automated method for the segmentation of individual microcalcifications in an area of the mammogram known to contain a cluster.

Biopsy↗
PubMed1994

Erythropoietin (EPO) levels in fetal rats after ritodrine and terbutaline administration.

Beta-2 sympathomimetics, such as terbutaline, have been shown to alter erythropoietin (EPO) secretion in animal studies. More recently introduced sympathomimetics, such as ritodrine, have been extensively used to inhibit uterine contractions in preterm labor. It has not been determined what effect ritodrine may have on EPO production. We investigated the effect of RD administered to rats in the last day of gestation on the dam and the fetuses' levels of EPO. Rats at the 20th day of gestation were given, under anesthesia, either 3000 micrograms/kg ritodrine over a 10-min period or a similar volume of saline as control (CTL). Fetuses were removed at 0 and 4 h after injection. Ritodrine administration produced a decrease of dam EPO (23.4 +/- 4.2 to 12.0 +/- 2.9 pmol/ml), while the CTL showed no changes. The fetuses from the ritodrine-injected dams exhibited a marked decline over the 4-h period, while the CTL fetuses did not change. In other experiments 500 micrograms terbutaline was administered daily during the last 5 days of rat gestation. The drug produced a significant decline in EPO at delivery time, but plasma EPO in the pups was unchanged. Blood hematocrits were comparable to those of controls. The data show that acute administration of ritodrine reduces fetal and dam plasma EPO, while long-term terbutaline treatment late in gestation alters maternal, but not fetal plasma EPO, indicating that neither drug has any direct regulatory effect on the erythropoietic ability of the fetuses.

Animals↗
PubMed1994

Use of texture parameters in the classification of soft tissue tumors.

Soft tissue tumors are a challenging group of tumors that presents wide morphologic variety. For pathologists, the degree of cellular differentiation, the cellular and nuclear polymorphism and the mitotic rate are major criteria for diagnosis. In image analysis, the architectural organization of such tumors shows local variations that can be understood as texture variations. This study introduced a method of measuring the architectural organization of soft tissue tumors from texture analysis of tissue sections at low magnification. We studied 40 cases of soft tissue tumors classified by pathologists into three groups according to their histologic patterns. Twelve texture parameters were calculated on subimages of 128 x 128 pixels. Our results show that tissue architecture evaluated by texture analysis provides good discrimination of myxoid, spindle cell and round cell tumors.

Cell Differentiation↗
PubMed1994

Grading of cystosarcoma phyllodes by texture analysis of tissue architecture.

Conventional histologic grading of cystosarcoma phyllodes of the breast has not been entirely successful in the prognosis of recurrence or metastasis. Our study first developed a tumor grade classification based on computerized texture features and then compared the classification to conventional grading of these tumors. Evaluation of the tissue architecture of histologic sections was obtained by measuring nine texture features on an image analysis system. Forty cases of cystosarcoma phyllodes were studied. Each parameter was calculated on subimages of 128 x 128 pixels. This size resulted from a preliminary study that confirmed that the difference between texture primitives depends on the area of subimages. We also compared our series to a panel of 20 extramammary sarcomas. The results show that tissue architecture evaluated by texture analysis allows good discrimination between benign, borderline and malignant cystosarcoma phyllodes. Furthermore, extramammary sarcomas and malignant cystosarcoma phyllodes were discriminated well in most cases.

Breast Neoplasms↗
PubMed1993

Hypertension secondary to renin-secreting juxtaglomerular cell tumor: case report and review of 38 cases.

A 15-year-old girl with severe high renin hypertension caused by a juxtaglomerular cell tumor (JCT) was successfully treated with the calcium channel blocker nifedipine until surgical removal effected a permanent cure. This case was incorporated into a review of the 37 cases previously published. Comparison of the children and adolescents with the adult population showed that the features of JCT were similar in the two groups except for the average duration of symptoms prior to diagnosis (pediatric group 2.6 years vs. 6.0 years for the adult group). Analysis of all 38 cases demonstrated the following: 1. Teenagers constituted the largest single population with JCT (39%) and approximately two-thirds of the entire population were female. 2. Many patients failed to show persistent hypokalemia despite high plasma renin activity and secondary hyperaldosteronism. 3. Renal angiography was initially negative in more than half the cases. 4. Renal vein renin failed to show lateralization to the affected kidney in 52% of the cases. 5. Computerized tomography demonstrated a renal mass in all of the cases in which it was performed, even when other imaging studies were negative. 6. Calcium channel blockers may evolve as the preferred treatment for the high renin hypertension of JCT.

Adenocarcinoma↗
PubMed1993

Atypical rectosigmoid histology in children with newly diagnosed ulcerative colitis.

BACKGROUND: In the untreated patient with inflammatory colitis, rectal sparing or patchy rectal inflammation is generally considered a sign of Crohn's disease (CD), rather than ulcerative colitis (UC). METHODS: The initial endoscopic rectosigmoid mucosal biopsies obtained at disease onset from 12 untreated children with UC who ultimately required surgery were blindly reviewed (randomly mixed with another 62 specimens obtained from children with CD or treated UC). Biopsies were classified as typical UC if there was diffuse, active inflammation and severe crypt destruction or distortion. Those with patchy, active inflammation and only mild crypt changes were classified as CD. Because all 12 subjects had ultimately been proven to have UC by examination of a subtotal colectomy specimen, for the purposes of this report biopsies read as either normal or CD were both considered evidence of atypical UC with rectal sparing. RESULTS: Five of 12 subjects (seven biopsies) had atypical histology. Mild, patchy inflammation was seen in six rectal or sigmoid biopsies, whereas one rectal biopsy was normal. The remaining seven subjects (10 biopsies) had diffuse inflammation. Two of five subjects with atypical biopsies had an endoscopically normal rectosigmoid, one had patchy inflammation, and the remaining two had diffuse endoscopic changes. All seven subjects with typical UC histology had diffuse endoscopic changes. Subjects with atypical findings could not be differentiated by age, duration, or types of symptoms at presentation, years of disease at colectomy, or indications for colectomy. CONCLUSIONS: Patchy or absent inflammation of the rectum and sigmoid can be present in untreated children with UC at disease onset. Because such children may be mistakenly diagnosed as having CD, these data must be considered when treatments or clinical research protocols are designed to include children with colitis.

Adolescent↗
PubMed1993

Correlation between clinical diagnoses and autopsy findings in critically ill children.

STUDY OBJECTIVE: To examine the correlation between clinical diagnoses and autopsy findings in children who die in the pediatric intensive care unit (PICU). DESIGN: Retrospective chart review. SETTING: PICU of a university-affiliated hospital. PATIENTS: A consecutive sample of patients who died in the PICU and had autopsies performed. MEASUREMENTS AND MAIN RESULTS: Of 193 patients who died during the 7 1/2-year study period, 50 (26%) had autopsies performed. The mean age was 34.7 months (range 15 hours to 17 years), and the mean length of stay in the PICU was 12.2 days (range 2 hours to 60 days). Major admitting diagnoses included postoperative cardiac surgery (19), nonoperative cardiac disease (7), hematologic/malignant disorder (5), and acquired immunodeficiency syndrome (5). There were 5 cases (10%) where autopsy revealed a major finding that, if known prior to death, would have altered clinical management and might have resulted in cure or prolonged survival. In another 9 patients (18%) the autopsy revealed major findings that, if known prior to death, would not have altered management. Eight of these findings related to the cause of death and 2 of them involved the basic disease. There was no correlation between new findings and either patient age or length of stay in the PICU. CONCLUSIONS: Despite modern diagnostic techniques, the autopsy continues to reveal valuable and unsuspected information.

Adolescent↗
PubMed1993

The morphologic relationship of sinus and fistula formation to intestinal stenoses in children with Crohn's disease.

Sinus and fistula (SF) formation in adults with Crohn's disease has been ascribed to increased intraluminal pressure from stenotic lesions or to inflammation. We retrospectively evaluated 55 surgically resected specimens from 30 children with Crohn's disease for stenotic lesions, sinuses, fistulas, and inflammation. Eighteen of 30 children had one operation, and there were 12 multiple surgeries. Thirty-one of 55 specimens (56%) contained stenoses. SF formation was seen in 16 of 31 specimens with stenosis; it developed proximal to the stenosis in seven patients, distal in five, and both proximal and distal in four. SF formation was also noted in 12/24 specimens without stenosis. In 93% of the cases, the SF was associated with moderate to severe inflammation. Although 56% of the patients had stenoses, SF frequently developed independent of stenosis. All SF were associated with inflammation. Therefore, inflammation rather than increased intraluminal pressure appears to be the primary factor in SF formation in children with Crohn's disease.

Adolescent↗
PubMed1992

The appendix in inflammatory bowel disease in children.

The morphologic characteristics of the colon in ulcerative colitis and Crohn's disease are well established, but specific appendiceal pathology is less clearly defined. In addition, the frequency of appendiceal involvement in children with inflammatory bowel disease has also not been delineated. We have determined the prevalence of appendiceal involvement in 41 children with inflammatory bowel disease (24 with Crohn's disease and 17 with ulcerative colitis) who required colonic resection and have defined the histopathologic characteristics of the appendix in these diseases. All appendices were abnormal. Specific changes of Crohn's disease or ulcerative colitis were observed respectively in 50% and 56% of the appendices in our patient population. Nonspecific changes only such as fibrous obliteration, serosal fibrosis and lymphoid and/or neuronal hyperplasia were noted in the remaining appendices. The severity of ileocolonic and appendiceal inflammation was similar in about two thirds of the patients with either type of inflammatory bowel disease.

Adolescent↗
PubMed1991

Bradykinin-induced oscillations of cell membrane potential in cells expressing the Ha-ras oncogene.

Products of ras genes are putative elements of growth factor signal transduction. However, the mechanism of action of these proteins in normal and malignant growth is as yet obscure. To test for functional consequences of ras oncogene expression, electrophysiological experiments were performed on NIH-3T3 fibroblasts transfected with a transforming Ha-ras MMTV-LTR construct expressing the oncogene on treatment with dexamethasone (+ras). Transfected cells in the absence of dexamethasone (-ras) and nontransfected cells in the presence of dexamethasone (oras) served as controls. In -ras and oras, bradykinin induces a single, transient hyperpolarization. In +ras, bradykinin elicits oscillations of cell membrane potential throughout the presence of the hormone by activation of calcium-sensitive K+ channels. The oscillations of cell membrane potential are abolished in the absence of extracellular calcium. As evident from fura 2 fluorescence, bradykinin leads to a transient increase of intracellular calcium both in the presence and absence of extracellular calcium. Oscillations of intracellular calcium could be observed in +ras cells, if bradykinin was applied at reduced extracellular sodium concentration possibly to impair calcium extrusion via the sodium/calcium exchange. Bradykinin induces oscillations of cell membrane potential similarly in -ras cells loaded with GTP[S], a nonhydrolyzable analogue of GTP. Thus, the altered response of ras oncogene expressing cells to bradykinin relates to the GTP binding property of the ras protein. It is concluded that in cells expressing ras oncogene but not in other fibroblasts bradykinin mimicks the effect of growth factors on the cell membrane.

Bradykinin↗
PubMed1991

Hepatic pathology in pediatric acquired immunodeficiency syndrome.

In a retrospective study we assessed the hepatic changes in children with the acquired immunodeficiency syndrome by reviewing 12 biopsy specimens and 48 autopsy specimens from 54 children. Hepatopathology differed in biopsy and autopsy material. In biopsy specimens, chronic active hepatitis with predominantly T8 lymphocytes by tissue immunochemistry was common (five of 12 specimens). Fatty degeneration and hepatocellular necrosis were either absent, mild, or patchy. On the other hand, at autopsy, chronic active hepatitis was not observed. The most prominent changes were extensive fatty degeneration, nonspecific portal mononuclear infiltration, portal fibrosis, and confluent (ischemic) necrosis. Opportunistic infections such as Mycobacterium avium-intracellulare (MAI) were noted only at autopsy. In addition, three unusual morphologic characteristics were noted: nodular lymphoplasmacytic portal infiltrate, a pseudosarcomatous variant of Mycobacterium avium-intracellulare infection, and multinucleated giant cells (foreign both type and giant cell transformation of hepatocytes).

Acquired Immunodeficiency Syndrome↗
PubMed1991

Erosion through the posterior gastric wall by a pancreatic pseudocyst secondary to gastric duplication.

Gastric duplications are the rarest form of enteric duplication. They account for about 20% of all gastrointestinal duplications. Delayed and missed diagnosis leads to prolonged morbidity and mortality. We report a case of a child with a gastric duplication cyst in the body of the pancreas, associated with a pancreatic pseudocyst that ultimately eroded into the posterior wall of the stomach.

Humans↗