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Biomedical subjects

D Kaiser

Publications and source records attributed to D Kaiser.

At least 163 records · Page 9Linked to original sources
PubMed1987

[Magnetic resonance tomography of intrathoracic tumors].

65 patients suspected of having intrathoracic masses were studied using magnetic resonance imaging (MRI) and computed tomography (CT). The intensity difference between mass and adjacent normal tissue or mediastinal fat was greater on MRI than on CT images. MRI was superior to CT in differentiating bronchogenic carcinomatous tumours from postobstructive pneumonia and/or lobar collapse. MRI images most clearly depicted obstructed mediastinal vessels and were also able to indicate intravenous flow reductions. The latter could be demonstrated by an increase of signal intensity within venous structures proximal to the obstruction. In patients with lung cancer no significant differences were found between the two imaging methods for the evaluation of tumour extent or node involvement.

Bronchogenic Cyst↗
PubMed1987

Expression of many developmentally regulated genes in Myxococcus depends on a sequence of cell interactions.

Certain developmental mutants of Myxococcus xanthus can be complemented extracellularly by wild-type cells. These mutants behave as if they are defective in cell-cell interactions that are required for development. There may be several different interactions because the mutants belong to four extracellular complementation groups (A, B, C, and D). We report here that B- and C- mutations change the pattern of gene expression during Myxococcus development as detected by transcriptional fusions to lacZ mediated by Tn5 lac. The mutant C locus reduced or abolished developmental beta-galactosidase expression from 15 lac fusions that normally begin to be expressed in wild-type cells after 6 hr of development. Expression of these C-dependent lac fusions was restored to C- mutants by adding wild-type cells. The C- mutation did not affect the expression of 10 lac fusions that normally begin to be expressed before 6 hr of development, indicating that the C-mediated cell-cell interaction is required beginning at about 6 hr of development. Cells require the B+ function very early in development because a B- mutation reduced or abolished developmental beta-galactosidase expression from all 26 lac fusions tested, including some that normally begin to be expressed at the onset of development. In a C- mutant and in a B- mutant, some lac fusions responded with reduced beta-galactosidase expression, whereas other fusions, which would normally begin beta-galactosidase expression at about the same time during development, expressed no beta-galactosidase, indicating that developmental genes within a given temporal class display different sensitivities to the absence of cell-cell interactions. Requirements for B+ and C+ function, as well as the previously described A+ function, appear to lie on the same developmental pathway.

DNA Transposable Elements↗
PubMed1987

Multilineage synergistic activity produced by a murine adherent marrow cell line.

We reported previously that a cell line (TC-1) derived from adherent marrow cells produced colony-stimulating factor 1 (CSF-1) and a separate activity that acts synergistically with CSF-1 to stimulate giant macrophage colonies. We now report that an activity in TC-1 conditioned media (CM) separate from CSF-1 also synergizes multilineage colony formation by pure interleukin 3 (IL 3) and a crude source of granulocyte-macrophage colony-stimulating activity (GM-CSA) (murine lung-conditioned media). IL 3-induced megakaryocyte colony formation is also synergized. The CSF-1-dependent synergistic activity is not blocked by antibodies to IL 3 and is characterized as a nondialyzable (mol wt cutoff 3,000), heat-stable (56 degrees C, 30') activity that binds to DE-52 cellulose under conditions in which IL 3 does not. This material has an apparent mol wt of approximately 200,000 by Sephadex G100 chromatography, and the bulk of it binds to Concanavalin A (Con A) and elutes off with alpha-methyl mannoside, indicating that it is a glycoprotein. As reported separately, these purified active fractions also have a pre-B cell-inducing activity. In addition, a non-IL 3 activity stimulates proliferation of the factor-dependent cell lines FDC-P1 and DA-1. These data indicate that an adherent marrow cell line produces a growth factor(s) that synergizes with IL 3, GM-CSA, and CSF-1 and induces pre-B cell formation. This may be an important regulator of early multilineage lymphohemopoiesis.

Animals↗
PubMed1987

[Nuclear magnetic resonance tomography of superior vena cava obstruction].

The potential of magnetic resonance tomography (MRT) to demonstrate the mediastinal veins was evaluated retrospectively in 6 patients with superior vena cava obstruction. In each instance, MRT provided detailed information about the extent of venous obstruction and the precise site of the causative oncological pathology. Transaxial images most clearly and unequivocally depicted obstructed superior vena cava. MRT was also able to indicate some secondary effects of superior vena cava obstruction such as slow intravenous flow. The latter could be demonstrated by a significant increase of signal intensity within venous structures proximal to the obstruction. Peripheral venous collaterals in the chest wall were better seen with contrast enhanced computed tomography scans.

Collateral Circulation↗
PubMed1986

A global analysis of developmentally regulated genes in Myxococcus xanthus.

Tn5 lac is a transposon that fuses the transcription of lacZ to exogenous promoters. We generated 2374 Tn5 lac insertion-containing strains of Myxococcus xanthus, a soil bacterium that undergoes multicellular development which culminates in the formation of spores. Thirty-six strains were identified that specifically increase beta-galactosidase expression at some particular time during development and these expression times range from minutes after starvation initiates development to 24 hr, when sporulation begins. Different maximum levels of beta-galactosidase expression were also observed and the maximum for many strains that begin beta-galactosidase expression late in development was observed only if spores were disrupted. Seven of the 36 strains display mild to severe defects in aggregation and/or sporulation, as did an additional five strains whose beta-galactosidase expression was not developmentally regulated. Restriction maps of the DNA adjacent to the Tn5 lac insertions that are developmentally regulated and/or cause developmental defects show that most of the 41 insertions are in different regions of the Myxococcus genome. The developmentally regulated Tn5 lac insertions described here provide a set of at least 29 new developmental markers for Myxococcus.

Bacterial Proteins↗
PubMed1986

Intercellular signaling is required for developmental gene expression in Myxococcus xanthus.

Certain developmental mutants of Myxococcus xanthus can be complemented (extracellularly) by wild-type cells. Insertions of Tn5 lac (a transposon which couples beta-galactosidase expression to exogenous promoters) into developmentally regulated genes were used to investigate extracellular complementation of the A group mutations. A- mutations reduced developmental beta-galactosidase expression from 18 of 21 Tn5 lac insertions tested and that expression was restored to A- Tn5 lac cells by adding wild-type cells. The earliest A-dependent Tn5 lac normally expresses beta-galactosidase at 1.5 hr of development indicating a developmental block at 1-2 hr in A- mutants. A substance which can rescue the expression of this early Tn5 lac is released by wild-type (A+) but not by A- cells. This substance appears in a cell-free wash of wild-type cells or in starvation buffer conditioned by wild-type cells 1-2 hr after development is initiated. The conditioned starvation buffer also restores normal morphological development to an A- mutant.

Bacterial Proteins↗
PubMed1985

Cell interactions in myxobacterial growth and development.

During their complex life cycle, myxobacteria manifest a number of cell interactions. These include contact-mediated interactions as well as those mediated by soluble extracellular signals. Some of these interactions are well-defined; in addition, the tools for molecular and genetic analysis of these interactions in Myxococcus xanthus are now available.

Microscopy, Electron, Scanning↗
PubMed1985

Disorganization of cultured vascular endothelial cell monolayers by fibrinogen fragment D.

Fibrinogen fragment D, which is heterogeneous, has several important biological functions. Human fibrinogen fragments D94 (molecular weight, 94,000), D78 (78,000), and E (52,000) were purified. Fragments D78 and D94 but not purified fibrinogen or fragment E specifically caused disorganization of bovine aortic endothelial cells cultured as monolayers. Within 2 hours of exposure to pathophysiological concentrations of fragment D, the confluent endothelial cells retracted from each other and projected pseudopodia. These disturbed cells subsequently became rounded and detached from the substrate. The actin present in stress fibers in stationary monolayer cells was diffusely redistributed in cells with fragment D-induced alterations in morphology. This effect was not observed in monolayers of kidney epithelial cells. The results demonstrate a specific effect of fibrinogen fragment D on the disorganization of cultured vascular endothelial cell monolayers and suggest that fragment D plays a role in the pathogenesis of syndromes with vascular endothelial damage.

Actins↗
PubMed1985

Development of three human small cell lung cancer models in nude mice.

The transplantation of seven human small cell lung cancers (SCLC) into athymic nude mice resulted in the development of three tumor lines that are suitable for study of biology and for tests of new drugs and combinations. They were characterized and the response to known drugs was determined. An identical tumor response was observed in the nude mouse system and in the patient in all four comparisons available.

Animals↗
PubMed1985

Alloplastic replacement of canine trachea with Dacron.

Two by two centimeter fenestrations were created in the cervical tracheae of 2 groups of 9 mongrels each during intubation anesthesia. In one group the defect was closed with a Dacron patch of 25 to 50 micron pore-size, while in the other group a Dacron patch of pore-size 125 to 150 micron was inserted. The implant was sealed with 1 ml of fibrin adhesive. Seven dogs of each group were evaluated. Implants made of low-porosity Dacron were not incorporated in any animal, but sloughed into the tracheal lumen. Contrarywise large-pore Dacron underwent connective tissue incorporation in all but one case. As early as 90, and even more so at 270, days granulation tissue rich in fibroblasts and histiocytes had grown into the implant. On the implant, a stroma formed which was epithelialized from the margin already after 90 days. After 200 and 270 days the implant was covered with a respiratory epithelium, however, scattered undifferentiated cells still could be found in its center. Porous prosthetic fabrics when used for partial tracheal replacement can be incorporated by connective tissue and can be epithelialized if the polymer is tissue-compatible, the pore-size of the implant ranges between 120 and 150 micron, the implant is sufficiently stable, and if infection is prevented by fibrin seal.

Animals↗
PubMed1985

Bilateral breast cancer. Risk reduction by contralateral biopsy.

Although survival from primary breast cancer has improved with earlier diagnosis and treatment, the management of the opposite breast is still in question. The risk factors for bilaterality are known, and preoperative mammography is occasionally helpful, but identification of early second breast cancer is very limited. Contralateral biopsy may provide a reasonable answer to the problem. During a 5-year period, 62 elective contralateral biopsies were performed in patients having mastectomies for primary breast cancer. This consisted of either a mirror image biopsy or, more commonly, a biopsy of the upper outer quadrant. Thirteen patients had simultaneous contralateral cancers, of whom two had clinically overt bilateral cancers and 11 (18%) had clinically occult malignancy. Seven of these 11 had both radiologically and clinically normal breasts. Thus, 11.3% had radiologically and clinically occult cancer demonstrated by biopsy. Surgical management consisted of total mastectomy with low axillary dissection for noninvasive cancers and modified radical mastectomy for invasive cancers. Pathologic findings of the dominant breast cancer and the contralateral lesion were: bilateral, noninvasive: three patients; invasive, noninvasive: (seven patients), and invasive, invasive: three patients. Although follow-up is short (median of 40 months), 82% of the patients who had clinically occult second-breast cancer remain free of disease. During a previous 8-year period, 37 of 500 primary breast cancer patients (7.4%) developed metachronous (33) or synchronous (4) second-breast primary cancers primarily diagnosed clinically or radiologically. Of these, 35 were invasive and two noninvasive cancers; 41% had nodal metastases. A selected "favorable group," 28 of these patients who were free of disease 3 years after their first cancer, was analyzed. The analysis showed that only 10 (36%) were surviving free of disease at 7 years; 25% were free of disease at 10 years. Although the incidence of clinically-recognized, second-primary breast cancer is relatively low, development of a second invasive cancer severely impairs patient survival. Contralateral biopsy would appear useful to identify patients with early invasive or preinvasive cancer in the second breast, which appears normal after clinical observation or mammography. It provides opportunity to reduce the risk of invasive cancer in that breast, as well as to provide important diagnostic and prognostic information.

Biopsy↗