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Biomedical subjects

K Weber

Publications and source records attributed to K Weber.

At least 847 records · Page 47Linked to original sources
PubMedDate not supplied

The prevention of recurrent fractures of the lower extremities in severe osteogenesis imperfecta using vacuum pants: a preliminary report in four patients.

Severe osteogenesis imperfecta results in frequent fracturing of lower extremity bones when the child assumes upright weightbearing. To prevent such breakage and to provide simple, comfortable standing, a special "vacuum pant" orthosis was designed and assessed in four patients. Not only has this enabled the family to help their children stand up safely and comfortably, but the frequency of fracturing has diminished. Bone densitometry studies of the tibia revealed an increase in both the mineral content (0.39 to 0.70 g/cm) and the bone density (0.44 g/cm2) above that expected for growth alone in one patient. The "vacuum pant" orthosis is a useful addition to the treatment program of the severe osteogenesis imperfecta child.

Child↗
PubMedDate not supplied

Early- and middle-aer components to clicks as response indices for neonatal hearing screening.

Early- and middle-component-averaged electroencephalic responses (AER) to monotic clicks at 60, 40 and 20 dB normal hearing level were elicited from 18 carefully selected normal neonates. Grand-composite AERs of the responses from all 18 babies showed stimulus-related configurations at all three stimulus levels. AERs for individual babies were more frequently identified as stimulus-related when poststimulus activity beyond 10 ms was included in response-identification procedures than when only the first 10 ms was observed.

Audiometry↗
PubMedDate not supplied

Apoptosis of human T-cells: induction by glucocorticoids or surface receptor ligation in vitro and ex vivo.

Activated T-cells are susceptible to induction of apoptosis or programmed cell death in response to ligation of several cell surface structures, including CD2, CD3, and CD95/Fas. These mechanisms may be important in the regulation of immune responses and in prevention of autoimmunity. We used flow cytometric quantitation of DNA strand breaks to detect T-cells committed to programmed cell death. Activated human peripheral blood T-lymphocytes, and freshly isolated human thymocytes underwent apoptosis when exposed to dexamethasone or to monoclonal antibodies directed at CD2 or CD3. Interleukin-2 reduced spontaneous or dexamethasone-induced apoptosis, but augmented apoptosis due to ligation of CD2. A neutralizing anti-Fas antibody reduced the amount of DNA strand breakage, not only in T-cells exposed to antibodies to CD2 or CD3, but also in dexamethasone-treated cultures. In vivo activated T-cells, from inflammatory synovial fluids, were sensitive to immediate induction of DNA strand breaks without prior in vitro activation by lectin and IL-2. Taken together, the results indicated that: 1. Human lymphocytes, like murine thymocytes, are sensitive to glucocorticoid-induced apoptosis, as well as to programmed cell death triggered through surface receptors; 2. The effects of IL-2 on T-cell apoptosis depend on the apoptotic stimulus; 3. Fas/Fas ligand interactions may be relevant for both membrane receptor and glucocorticoid-induced cell death; and 4. Induction of T-cell apoptosis may be important in therapeutic effects of glucocorticoids in human disease.

Administration, Topical↗
PubMedDate not supplied

Antitumoral effects of an intravesically applied aqueous mistletoe extract on urinary bladder carcinoma MB49 in mice.

The objective of the present study was to investigate the effects of a locally applied aqueous mistletoe extract (AME) on the growth of urinary bladder carcinoma MB49 in an orthotopic murine model. On day 1, a total of 4 x 10(4) tumor cells was implanted into the bladder of female C57BL/6J mice. The animals were then randomly allocated to three groups of 13 mice each. From day 11 onwards, AME was given intravesically 3 days a week for 4 consecutive weeks at concentrations related to 30 or 300 ng bioactive mistletoe lectin (ML)/ml. The animals received a total volume of 0.1 ml. In the control group, 39% of the mice survived to the end of the scheduled study period in comparison to 69% and 85% in the groups treated with 30 or 300 ng ML/ml, respectively. At necropsy, 80% of the surviving control animals showed a visible solid bladder tumor, whereas only 56% and 18% had tumors in the treated groups. In both cases, the differences were statistically significant at the high concentration in comparison to controls (p < 0.05). A non-significant effect was observed regarding the formation of multiple metastases (40% in controls vs 33% and 18% in the treated groups). From the results, it was concluded that under the conditions described, AME shows antitumoral activity which is considered to be mainly due to the cytotoxic properties of mistletoe lectins, the main effective constituents of mistletoe extracts.

Administration, Intravesical↗
PubMedDate not supplied

Keratin-positive reticulum cells in fine needle aspirates and touch imprints of hyperplastic lymph nodes. A possible pitfall in the immunocytochemical diagnosis of metastatic carcinoma.

Fine needle aspirates and touch imprints of 36 hyperplastic (reactive) lymph nodes were tested for the presence of keratin and desmin. Keratin-positive cells with morphologic characteristics corresponding to extrafollicular (fibroblastic) reticulum cells were found in 18% of the fine needle aspirates and 42% of the touch imprints. The number of keratin-positive reticulum cells varied from 1 to greater than 30 per slide. Desmin-positive cells with similar morphology were found in 23% of fine needle aspirates and 37% of touch imprints, and the number of such cells per slide ranged from 2 to greater than 70. The relatively frequent occurrence of keratin-positive reticulum cells in these preparations from hyperplastic lymph nodes should be taken into account if keratin antibodies are used to search for carcinoma micrometastases.

Biopsy, Needle↗
PubMedDate not supplied

Immunocytochemistry on fine needle aspirates in paraffin miniblocks.

A simplified method of processing of fine needle aspirates for paraffin miniblocks suitable for both morphologic and immunocytochemical evaluation is described. Aspirates were fixed in ethanol at 4 degrees C, dehydrated in acetone and xylene and embedded in paraffin (58 degrees C). All steps were carried out in a single Eppendorf centrifuge tube; the total process took less than four hours. Deparaffinized sections were stained using the alkaline phosphatase-antialkaline phosphatase technique with monoclonal and conventional antibodies helpful in the differential cytologic diagnosis of alcohol-fixed aspiration biopsy specimens. Antibodies to keratin, vimentin, desmin, neurofilaments, glial fibrillary acidic protein, leukocyte-common antigen, synaptophysin and immunoglobulin kappa and lambda light chains reacted positively on the miniblock material. Since the paraffin miniblocks combine the histologic pattern of the tumor with the differentiation-specific information provided by immunocytochemistry, their use can improve the accuracy of tumor typing in aspirates.

Antigens, CD↗
PubMedDate not supplied

Intermediate filament typing of tumor cells in fine needle aspirates by means of monoclonal antibodies.

Well-characterized monoclonal antibodies directed against different intermediate filament proteins were used in the typing of tumor cells in 30 fine needle aspiration (FNA) biopsy specimens received for routine cytologic examination to assess the value of intermediate filament typing in FNA cytology. Tumors from sites that included liver, large bowel, pancreas, breast, skin, thyroid, thigh and kidney were examined with monoclonal antibodies specific for either all keratins or keratin subsets, vimentin, desmin or specific neurofilament polypeptides. Intermediate filament typing helped to confirm, revise or refine the diagnoses made by light microscopy and provided information of value in the classification of tumors of uncertain origin.

Antibodies, Monoclonal↗
PubMedDate not supplied

Neuroendocrine (Merkel-cell) carcinoma of the skin. Cytology, intermediate filament typing and ultrastructure of tumor cells in fine needle aspirates.

The light and transmission electron microscopic findings and the intermediate filament typing of tumor cells from fine needle aspirates of primary, recurrent and metastatic neuroendocrine (Merkel-cell) carcinoma of the skin are described. The tumor cells in the smears coexpressed keratins and neurofilaments and were characterized by "intermediate filament buttons," i.e., buttonlike fragments of cytoplasm of tumor cells, which could be observed either by staining with intermediate filament-specific antibodies using immunofluorescence or by their appearance in hematoxylin-and-eosin-stained smears. These features may help in the differential diagnosis of fine needle aspirates of neuroendocrine carcinomas of the skin.

Adenocarcinoma↗
PubMedDate not supplied

Diagnostic significance of coexpression of intermediate filaments in fine needle aspirates of human tumors.

A study was undertaken of the diagnostic significance of the coexpression of intermediate filaments in fine needle aspirates of human tumors. Three types of coexpression were found: (1) true coexpression, in which tumor cells simultaneously express more than one intermediate filament protein; (2) pseudocoexpression, in which various tumor cell types from histogenetically different parts of a complex tumor show different results; and (3) false coexpression, in which tumor cells with one or two types of intermediate filaments are present together with benign cells expressing a different filament type. True coexpression of vimentin and keratin was documented in renal cell carcinomas, endometrial carcinomas, certain thyroid carcinomas and Hürthle cell adenomas. Coexpression of keratin and neurofilaments was seen in Merkel cell carcinomas, and coexpression of desmin and vimentin was found in leiomyosarcomas. Keratin, vimentin and neurofilament expression was seen in medullary thyroid carcinomas, and keratin, vimentin and glial fibrillary acidic protein expression was observed in pleomorphic adenomas of the salivary gland. Pseudocoexpression was noted in synovial sarcoma, epithelioid sarcoma, benign cystosarcoma phyllodes of the breast, teratocarcinoma, malignant granular cell tumor, progonoma, Wilms' tumor and triton tumor. Sources of false coexpression are also discussed.

Biopsy, Needle↗
PubMedDate not supplied

Coexpression of glial fibrillary acid protein, keratin and vimentin. A unique feature useful in the diagnosis of pleomorphic adenoma of the salivary gland in fine needle aspiration biopsy smears.

Positive staining for glial fibrillary acidic protein (GFAP) of tumor cells in fine needle aspirates of 11 of 12 pleomorphic adenomas of the parotid gland is reported. Tumor cells in these neoplasms also coexpressed keratin and vimentin to varying extents. Coexpression of GFAP, keratin and vimentin in tumor cells in aspirates is an unusual feature, so far demonstrated only in pleomorphic adenomas. Thus, intermediate filament typing may help to distinguish: (1) pleomorphic adenomas of the salivary glands from head and neck tumors of nonsalivary gland origin; (2) intracranial metastases of malignant mixed tumors of the salivary gland from gliomas; and (3) pleomorphic adenomas from extracranial gliomas.

Adenoma, Pleomorphic↗
PubMedDate not supplied

Diagnosis of metastatic renal cell and thyroid carcinomas by intermediate filament typing and cytology of tumor cells in fine needle aspirates.

Coexpression of keratin and vimentin was found in carcinoma cells of 13 fine needle aspirates of metastatic lesions that showed some cytologic features considered to be consistent with a renal or thyroid origin, but in which a large number of other possible primary sites would have to be taken into account on the basis of the morphologic evidence alone. Immunochemistry thus narrowed the cytologic differential diagnosis to thyroid, renal, endometrial and ovarian carcinomas, which are known to show true coexpression of keratin and vimentin. In most cases, clinical data available at the time of the fine needle aspiration supported the thyroid or renal origin of the carcinoma cells found in the aspirates. In two cases, which lacked significant clinical information, the diagnosis of metastatic renal cell carcinoma was provided on the basis of the combined morphologic and immunocytochemical evidence. In these two cases, computed tomography or ultrasonography revealed kidney tumors, which were removed and confirmed histologically to be clear cell carcinomas.

Adenocarcinoma↗
PubMedDate not supplied

Transporting children in body casts.

Automotive restraint systems for children in body or hip spica casts, who cannot be accommodated by conventional child restraints or seat belts, were investigated. A car bed restraint and a harness vest restraint were subjected to simulated 30-miles/h crash tests to assess their effectiveness. The successful systems were then tried by patients and their families and found to be convenient as well. Details of the testing, potential limitations of the systems, and a subsequent actual crash experience are reported.

Casts, Surgical↗
PubMedDate not supplied

Decisive role of intermediate filament typing of tumor cells in the differential diagnosis of difficult fine needle aspirates.

Thirty-six diagnostically difficult fine needle aspirates from enlarged lymph nodes and malignant soft tissue tumors, containing tumor cells with scanty or no obvious light microscopic features indicative of their differentiation, were assessed by a panel of six cytopathologists. Their diagnoses were recorded and then compared with the definitive diagnosis established by combining the cytologic findings with the results of intermediate filament typing of tumor cells in the smears using monoclonal antibodies specific for each filament type. The results show that use of these antibodies can markedly improve the accuracy of the cytologic diagnosis of tumor type as well as revise or prevent erroneous cytologic diagnoses in difficult cases. This pertains especially to the differential diagnoses of carcinoma versus malignant lymphoma, carcinoma versus malignant melanoma, carcinoma versus sarcoma and squamous carcinoma versus carcinoma of simple epithelia. Intermediate filament typing of tumor cells in aspirates as an objective histogenetic criterium makes the differential diagnosis of the difficult aspirates much more reliable and reproducible, provided that appropriate questions are asked, monoclonal antibodies with well-defined specificities are used and the antigenicity of the intermediate filaments in smears is preserved.

Adult↗
PubMedDate not supplied

Differential diagnosis of lymph node aspirates by intermediate filament typing of tumor cells.

Twenty-one lymph node aspirates for which a differential diagnosis was difficult or not possible by light microscopy alone were selected for further study by intermediate filament typing. The use of four monoclonal antibodies specific for different keratin subsets or for vimentin resulted in a definitive diagnosis in all instances. The results show that use of these antibodies can improve the accuracy of cytologic diagnosis and provide further evidence that intermediate filament typing can help differentiate (1) malignant melanoma from adenocarcinoma, (2) malignant lymphoma from small-cell anaplastic carcinoma and (3) squamous-cell carcinoma from adenocarcinoma. Intermediate filament typing can also be used to identify very small numbers of carcinoma cells in specimens that are apparently negative for tumor cells by light microscopy. The method is quick, relatively simple, reliable and unambiguous, provided that appropriate questions are asked and antibodies with well-defined specificities are used.

Antibodies, Monoclonal↗