Papers by Reidar Albrechtsen
PubMed, May 1, 1988
Silent pituitary adenomas were compared with hormonally active tumors taking into account the siz... more Silent pituitary adenomas were compared with hormonally active tumors taking into account the size, number, and ultrastructural characteristics of secretory granules (SG). The study group (a total of 79 primary pituitary adenomas) comprised 27 silent, 21 growth hormone (GH)-producing-, 16 prolactin (PRL)-producing-, 5 GH-PRL-producing- and 10 adrenocorticotropic hormone (ACTH)-producing adenomas. The SG of silent adenomas were significantly smaller than SG in endocrine active adenomas. All hormonally inactive tumors also contained small (mean, 94 nm) specific cytoplasmic granules, designated "silent adenoma granules" (SIG). The fine structural features of the SIG included: a flocculent, granular material occupying an eccentric position in a larger vesicle limited by a double membrane. In the silent adenomas this particular granule was present in up to 90% of the adenoma cells and constituted approximately 10 to 50% of the granules in each cell. These granules were not seen in hormonally active tumors and considered therefore diagnostic of silent pituitary adenomas.
Bookmarks Related papers MentionsView impact
PubMed, May 1, 1976
Twelve patients with histologically verified polycystic ovary syndrome were investigated with spe... more Twelve patients with histologically verified polycystic ovary syndrome were investigated with special regard given to the effect of wedge resection on androgen status. Adrenal disorders were excluded in every case by determination of cortisol and corticosterone metabolites. Prior to and at least 6 months after surgery all patients were subjected to adrenal stimulation followed by adrenal suppression and ovarian stimulation. Comparison between pre- and postoperative studies revealed that only an insignificant reduction in the excretion of 17-ketosteroid had occurred and, although at lower levels, the stimulatory effect of hCG on ovarian androgens was still present. Clinically, 10 patients had had regular periods at followup, and 3 had become pregnant. In no case had hair growth slowed, bu the rate had declined. Seemingly, wedge resection does not significantly influence the biochemical pattern connected with the polycystic ovary syndrome.
Bookmarks Related papers MentionsView impact
PubMed, 1972
Bookmarks Related papers MentionsView impact
PubMed, Apr 1, 1981
Laminin, a glycoprotein antigenically similar or identical to a component of epithelial basement ... more Laminin, a glycoprotein antigenically similar or identical to a component of epithelial basement membranes, was identified as a major component of the abundant extracellular matrix synthesized by an experimentally induced rat yolk sac tumor. Immunocytochemical staining revealed laminin in cultured tumor cells as well as in their extracellular matrix. The presence of soluble laminin in the culture media of the tumor cells was demonstrated using metabolic labeling followed by identification by immunoprecipitation and sodium dodecyl sulfate:polyacrylamide gel electrophoresis. This revealed two polypeptides with molecular weights of approximately 200,000 and 400,000. These comigrated with the polypeptides of mouse laminin isolated previously. The yolk sac tumor tissue grown in vivo contained laminin in the tumor cells and in the extracellular material as evidenced by immunofluorescence and immunoperoxidase staining. Immunization with the tumor matrix resulted in an antiserum that contained antilaminin and natifibronectin and was made specific for laminin by absorption with fibronectin. This antiserum precipitated laminin polypeptides from culture medium of yolk sac tumour cells and stained basement membranes in rat tissues in a manner indistinguishable from antilaminin. The presence of laminin in rat yolk sac cells, the presumed origin of our yolk sac tumor, was studied in some detail. Laminin was found to be present in normal cells of the visceral as well as the parietal yolk sac layer and in their basement membranes suggesting, but not proving, that both types of cells have ability to synthesize laminin. Production of laminin and the presence of laminin-containing basement membrane material may be important for the biological behavior of the yolk sac tumor. This tumor will also be a useful source of laminin for chemical and biological characterization of this basement membrane protein.
Bookmarks Related papers MentionsView impact
Cell Reports, Dec 1, 2016
Bookmarks Related papers MentionsView impact
PubMed, Mar 1, 1992
The expression of laminin subunits (A, B1, B2, S and M) in the perisinusoidal space of the rat li... more The expression of laminin subunits (A, B1, B2, S and M) in the perisinusoidal space of the rat liver was studied in early postnatal life, in the adult, and after partial hepatectomy. In the perisinusoidal space of the normal adult rat, laminin was detected with polyclonal antibodies only in small streaks of basement membranes extending from the portobiliary tract and to a lesser degree from the central vein. Occasionally, droplets of laminin immunoreactivity were also found along the intervening portions of the perisinusoidal spaces. All morphologically identifiable basement membranes of the rat liver (biliary ducts and blood vessels) irrespective of the age of animals exhibited B1, B2 and S immunoreactivity. Laminin A was restricted to the larger blood vessels and could not be detected in the biliary ducts. In the adult rat, immunoreactivity for the A-like M subunit was absent except for some negligible immunostaining of the blood vessels. In the neonatal rat strong linear laminin immunoreactivity was present in the perisinusoidal spaces throughout the entire lobule. Structurally, this laminin is not organized into a basement membrane as defined by electron microscopy. The perisinusoidal laminin was reactive with antibodies to B1, B2, S and M but the A subunit was absent. Sequential immunohistochemical studies of progressively older animals revealed that B1, B2, S and M immunoreactivity was weak in the perisinusoidal spaces before birth but during the postnatal life distinct linear immunoreactivities appeared. Most intense immunoreactivity was present at 1 to 2 weeks after birth. The perisinusoidal laminin gradually disappeared in growing animals and by 6 to 8 weeks basically no laminin could be detected in this location. By Northern blot analysis increased levels of B1 and B2 were detected in neonatal rats as compared to adult rats. S-laminin mRNA could readily be demonstrated in neonatal rat livers by Northern blot analysis, whereas A and M could not. Expression of S and M-laminin transcripts were demonstrated by polymerase chain reaction, but we were unable to obtain a laminin A product. After partial hepatectomy a transient laminin immunoreactivity, comparable to that in the neonatal rats, was detected in the perisinusoidal spaces. Laminin was most prominent 3 days after resection and reacted with antibodies to B1, B2, S and M. No A subunit could be detected in this extracellular matrix.(ABSTRACT TRUNCATED AT 400 WORDS)
Bookmarks Related papers MentionsView impact
Differentiation, Nov 1, 1985
Using immunological assays, we determined the relationship between the heparan sulfate proteoglyc... more Using immunological assays, we determined the relationship between the heparan sulfate proteoglycans produced by two different murine basement-membrane-producing tumors, i.e., the mouse Engelbreth-Holm-Swarm (EHS) tumor and the L2 rat yolk-sac tumor. Antibodies prepared against the heparan sulfate proteoglycans obtained from these two sources immunoprecipitated the same precursor protein with a molecular mass of 400,000 daltons from 35S-methionine pulse-labeled cells of both tumors. Immunohistochemistry showed the heparan sulfate proteoglycan to be distributed in the extracellular matrix and also in the native basement membrane of surrounding normal murine tissues. Blocking and ELISA assays demonstrated that the antibodies recognized both antigens. Using techniques involving the chemical and enzymatic degradation of 35S-sulfate-labeled glycosaminoglycans, the mouse EHS tumor cells were found to produce mainly heparan sulfate (75%) along with smaller amounts of chondroitin sulfate (19%), whereas the L2 rat yolk-sac tumor produced mainly chondroitin sulfate (76%) with smaller amounts of heparan sulfate (21%). We conclude that these two murine basement-membrane-producing tumors elaborate an immunologically and structurally similar type of high-molecular-weight heparan sulfate proteoglycan which subsequently becomes incorporated into basement-membrane-like material.
Bookmarks Related papers MentionsView impact
Experimental Cell Research, Oct 1, 2005
Bookmarks Related papers MentionsView impact
PubMed, Aug 1, 1988
The identification and cDNA cloning of bone-enriched osteonectin and parietal endoderm-enriched S... more The identification and cDNA cloning of bone-enriched osteonectin and parietal endoderm-enriched SPARC indicated that these proteins share greater than 90% homology. The present study reports substantial expression of this Mr 43,000 protein in human decidua and carcinoma. Metabolic labeling of human decidua tissue in organ culture demonstrated significant osteonectin biosynthesis. Further, Northern analysis and in situ hybridization showed that the osteonectin mRNA level in human decidua is very high. Immunohistochemically, the large mature decidual cells exhibited faint cytoplasmic immunoreactivity with antibodies to osteonectin and a distinct immunoreactivity of the newly deposited basement membranes encircling these cells. The intermediate-sized decidual cells exhibited a strong cytoplasmic immunostaining with antibodies to osteonectin. The small elongated stromal cells were devoid of osteonectin immunoreactivity. Blood vessels exhibited variable positive immunoreactivity. The osteonectin expression in 38 cases of human carcinomas was examined. In well-differentiated carcinomas osteonectin immunoreactivity was located in the basement membrane area, codistributing with laminin. Cytoplasmic osteonectin immunoreactivity was found in poorly differentiated carcinomas. Stromal cells in the peritumoral tissue and some vessels were immunoreactive. Using in situ hybridization, it appeared that both the tumor cells and the stromal cells contained osteonectin transcripts. In normal steady state human nonosseus tissues investigated, osteonectin was found inconsistently in the basement membranes only, as based on the present immunohistochemical technique. These results suggest that the osteonectin/SPARC gene appears activated in certain human tissues characterized by de novo formation of basement membrane.
Bookmarks Related papers MentionsView impact
PubMed, Nov 1, 1997
The role of the integrin alpha 6 beta 1 in breast carcinoma progression was studied by targeted e... more The role of the integrin alpha 6 beta 1 in breast carcinoma progression was studied by targeted elimination of this integrin in MDA-MB-435 cells, a human breast carcinoma cell line that is highly metastatic in athymic mice. The strategy used is based on the finding that expression of a cytoplasmic domain deletion mutant of the beta 4-integrin subunit (beta 4-delta CYT) in MDA-MB-435 cells eliminates formation of the alpha 6 beta 1 heterodimer. MDA-MB-435 cells that lacked alpha 6 beta 1 expression (beta 4-delta CYT transfectants) formed tumors in athymic mice that were suppressed in their growth and that exhibited a significant increase in apoptosis in comparison to the control tumors. Unlike the control MDA-MB-435 cells, the beta 4-delta CYT transfectants were unable to establish metastatic foci in the lungs. Also, the control transfectants grew substantially better than the beta 4-delta CYT transfectants in the liver after intrahepatic injection because of extensive apoptosis in the beta 4-delta CYT transfectants. These data suggest that a major function of the alpha 6 beta 1 integrin in breast carcinoma is to facilitate tumorigenesis and promote tumor cell survival in distant organs.
Bookmarks Related papers MentionsView impact
PubMed, Dec 1, 1985
Human decidual cells of early and late pregnancy were studied immunochemically and ultrastructura... more Human decidual cells of early and late pregnancy were studied immunochemically and ultrastructurally with respect to the presence and nature of pericellular basement membrane material. The most prominent cell type in decidual tissue of both early and late pregnancy were large, mature epithelioid decidual cells (greater than 25 micron) with a distinct pericellular basement membrane, containing at least laminin, type IV collagen, heparan sulfate proteoglycan, and fibronectin. Laminin was extracted from the decidual tissue at a concentration of 3 micrograms/gm as measured by enzyme-linked immunosorbent assay. Biosynthesis of laminin was shown by [35S]methionine labeling of short term organ cultures of decidual tissue followed by immunoprecipation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and fluorography. The laminin chains migrated with the apparent molecular weights of 300 and 200 kilodaltons under reducing conditions. Two other separate populations of cells were apparent in the decidual tissue of early pregnancy. A smaller group of rounded intermediate sized (15 to 25 micron) decidual cells had focal deposits basement membrane immunoreactive material scattered at the cell surfaces. Ultrastructurally, clumps of electron dense basement membrane material were present in close vicinity to the cell membrane. Occasional populations of small (greater than 15 micron) elongated fibroblastic-like cells were identified which did not display any immunoreactivity for any of the investigated basement membrane components. The two latter populations of decidual cells were not observed in the decidual tissue investigated from the placental bed of late pregnancy. It is suggested that these three types of decidual cells might represent various stages of the sequential differentiation of stromal cells into decidual cells of the pregnant endometrium. Predecidualization of the human endometrium, which is seen in the late secretory phase of the normal menstrual cycle and in some states of hyperplasia, was also shown to be accompanied by the presence of deposits of laminin-positive material at the cell surfaces. In the latter case, these cells resembled the intermediate sized decidual cells of the pregnant endometrium. In conclusion, the results suggest that the process of decidualization and predecidualization can be characterized morphologically and immunochemically by the accumulation of basement membrane material in specific decidua cell subpopulations.
Bookmarks Related papers MentionsView impact
PubMed, Dec 1, 1981
The distribution of the basement membrane glycoprotein laminin was studied by the immunoperoxidas... more The distribution of the basement membrane glycoprotein laminin was studied by the immunoperoxidase technique in benign and malignant human breast tissue and in axillary lymph nodes from patients with breast cancer. An antiserum prepared against rat laminin was used. The specificity of this antiserum against human laminin was studied using the FL cell line of human epithelial-like cells derived from normal amniotic membrane. The antiserum reacted with these cells in immunoperoxidase staining and precipitated metabolically labeled secreted polypeptides which comigrated with polypeptides with molecular weights of 400,000 and 200,000 of rat laminin in sodium dodecyl sulfate:polyacrylamide gel electrophoresis. The neoplastic cells in malignant breast tissues showed strong cytoplasmic staining for laminin, and a positive reaction was aslo found in lymph node metastases. In some cases in which only micrometastases were present, these cells also stained strongly for laminin. In nonmalignant breast tissues, the epithelial cells of the duct were positive for laminin, but the staining was weaker than in the carcinomas. Pretreatment of the fixed tissue sections with trypsin markedly enhanced the staining of basement membranes for laminin. In trypsin-treated sections of normal breast tissue and benign lesions, the laminin staining delineated continuous basement membranes. In carcinomas representing the more differentiated types, basement membranes presumably produced by the tumor cells could be revealed by laminin staining, but they were thinner and discontinuous. The poorly differentiated carcinomas lacked organized basement membranes detectable by laminin staining. Our studies suggest that staining for laminin may be a useful adjunct test for detection of micrometatases in lymph nodes. The correlation of disintegration of the laminin-containing basement membranes of tumors with increasingly anaplastic appearance supports the notion that basement membranes may play a role in tumor invasion.
Bookmarks Related papers MentionsView impact
Cancer Research, Jun 1, 2005
Bookmarks Related papers MentionsView impact
Journal of Biological Chemistry, 1998
Bookmarks Related papers MentionsView impact
Nature, Oct 1, 1977
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Cancer Research, Apr 15, 2006
BACKGROUND: Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that has ... more BACKGROUND: Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that has recently been implicated to play a role in carcinogenesis in a variety of systems. MIF regulates both innate and adaptive immune responses and can alter cell cycle events by ...
Bookmarks Related papers MentionsView impact
Biochemical and Biophysical Research Communications, Sep 1, 1998
The laminin alpha5 chain is a component of the basement membranes of many developing and adult ti... more The laminin alpha5 chain is a component of the basement membranes of many developing and adult tissues. The mouse laminin alpha5 chain gene (Lama5) has been mapped close to the locus of the semidominant ragged (Ra) mutation on distal chromosome 2. The cause of the Ra mutation, which is usually lethal in the homozygous state, has not been determined. We have investigated whether a defect in Lama5 is responsible for the ragged mutation, using the RaJ strain. No differences in the level of the laminin alpha5 chain transcript were found in placental RNA from homozygous RaJ mutant embryos compared to normal littermates. Antiserum raised against a recombinant laminin alpha5 chain polypeptide stained the basement membranes of both normal and homozygous mutant embryos to a similar extent. More precise mapping of Lama5 on an interspecific Ra backcross indicated that Lama5 is proximal to the Ra locus. These results exclude Lama5 as a candidate gene for the Ra mutation.
Bookmarks Related papers MentionsView impact
Uploads
Papers by Reidar Albrechtsen