Gangliosides inhibit 125I-labeled thyrotropin binding to the thyrotropin receptors on bovine thyroid plasma membranes, on guinea pig retro-orbital tissue plasma membranes, and on human adipocyte membranes. This inhibition by gangliosides is critically altered by the number and location of the sialic acid residues within the ganglioside structure, the efficacy of inhibition having the following order: GD1b greater than GT1 greater than GM1 greater than GM2 = GM3 greater than GD1a. The inhibition results from the interaction of thyrotropin and gangliosides, rather than the interaction of membrane and gangliosides. Fluorescence studies show that the inhibition is associated with a distinct conformational change of the thyrotropin molecule and that the progression from a "noninhibitory conformation" to an "inhibitory conformation" parallels exactly the order of effectiveness in inhibiting 125I-labeled thyrotropin binding. The ganglioside inhibition of 125I-labeled thyrotropin binding appears to be hormonally specific in that it is not affected by albumin, glucagon, insulin, prolactin, follicle-stimulating hormone, growth hormone, or corticotropin. The possibility that a ganglioside or ganglioside-like structure is a component of the thyrotropin receptor is suggested by the finding that gangliosides more complex than N-acetylneuraminylgalactosylglucosylceramide are present in bovine thyroid membranes in much higher quantities than have been previously found in extraneural tissue. The finding that the B component of cholera toxin, which also interacts with gangliosides, has a peptide sequence in common with the beta subunit of thyrotropin, suggests that thyrotropin and cholera toxin may be analogous in their mode of action on the membrane.

Adipose Tissue↗

PubMed1974

Computer analysis of ultrasoundcardiograms.

Explore the source record for details and available documents.

Cardiac Volume↗

PubMedDate not supplied

Production of discrete high specific activity DNA probes using the polymerase chain reaction.

Conditions are described for the synthesis of discrete DNA probes with high specific activity using the polymerase chain reaction. This method enables the production of DNA probes between any two oligonucleotide sequences from cloned or uncloned templates. These probes are uniform in length and their specific activity (1 x 10(9) cpm/microgram) is comparable to probes produced by other methods.

Cytidine Triphosphate↗

PubMedDate not supplied

Feasibility of hepatocellular transplantation via the umbilical vein in prenatal and perinatal lambs.

Hepatocellular transplantation has previously been performed in experimental animals by infusion of hepatocyte suspensions into the spleen or portal venous system. Cells injected into these sites flow to the liver and engraft within the hepatic parenchyma. We designed this study to evaluate the feasibility of hepatocellular transplantation through the umbilical vein in the prenatal or perinatal periods. Allogeneic sheep hepatocytes were harvested, stained with the vital fluorescent dye DiI, and injected into the umbilical vein of fetal lambs at 85% gestation and term. Hemodynamic studies performed to assess the physiological impact of transplantation on the recipient animal demonstrated that the procedure was well tolerated. No significant short-term complications were encountered and no lesions were found by conventional histological examination at necropsy 1-17 days after transplantation. Engrafted cells were identified within the liver by fluorescent microscopy and flow cytometry in 4/7 animals constituting 1.2-5% of the hepatocyte population. Fluorescent cellular material with the morphology of hepatocytes, noncellular material, and fluorescent phagocytic cells were seen occasionally in other organs including lung, brain, adrenal, and placenta. These studies demonstrate the feasibility of performing hepatocellular transplantation in the fetus via the umbilical vein in experimental animals.

Amniotic Fluid↗

PubMedDate not supplied

Effective cryopreservation and long-term storage of primary human hepatocytes with recovery of viability, differentiation, and replicative potential.

Despite reports of successful cryopreservation of primary human hepatocytes, existing methods do not produce sufficient recovery of viable cells to meet the needs of basic research or clinical trials of hepatocellular transplantation. We now describe a protocol for efficient cryopreservation of primary human hepatocytes using University of Wisconsin (UW) solution, fetal bovine serum, and dimethyl sulfoxide (DMSO). This method provides > 90% viability of differentiated, primary human hepatocytes 8 mo after cryopreservation as measured by trypan blue exclusion, preserves hepatocyte morphology, liver-specific gene expression (alpha 1 antitrypsin), and replication. The effectiveness of UW solution as a cryopreservative agent suggests that metabolic as well as ultrastructural factors may be important in the effective cryopreservation of primary human hepatocytes. The present method represents an effective protocol for cryopreserving differentiated primary human hepatocytes for research. This method may allow characterization and banking of human hepatocytes for clinical applications, including hepatocellular transplantation and hepatic assist devices.

Cell Differentiation↗