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Biomedical subjects

A Destree

Publications and source records attributed to A Destree.

13 recordsLinked to original sources
PubMed2005

Prenatal diagnosis of trisomy 6 mosaicism.

We report on a fetus with multiple congenital anomalies detected at the prenatal ultrasound examination and a trisomy 6 mosaicism in the amniocytes. The pregnancy was interrupted in the 18th gestational week and the autopsy revealed malformations including cleft right hand, arthrogryposis and hypoplasia of the 4th digit of the left hand, syndactylies and overlapping toes, facial dysmorphism with hypertelorism and low-set ears, ventricular septum defect (VSD), intestinal malrotation and scoliosis. Trisomy 6 mosaicism was detected in cultured amniocytes (13.3%), confirmed in umbilical cord fibroblasts (40%) and by fluorescence in situ hybridization on other fetal tissues. Trisomy 6 mosaicism is a very rare finding with only eight cases previously reported to our best knowledge.

Abnormalities, Multiple↗
PubMed1999

Proteasome inhibitors: a novel class of potent and effective antitumor agents.

The ubiquitin-proteasome pathway plays a critical role in the regulated degradation of proteins involved in cell cycle control and tumor growth. Dysregulating the degradation of such proteins should have profound effects on tumor growth and cause cells to undergo apoptosis. To test this hypothesis, we developed a novel series of proteasome inhibitors, exemplified by PS-341, which we describe here. As determined by the National Cancer Institute in vitro screen, PS-341 has substantial cytotoxicity against a broad range of human tumor cells, including prostate cancer cell lines. The PC-3 prostate cell line was, therefore, chosen to further examine the antitumor activity of PS-341. In vitro, PS-341 elicits proteasome inhibition, leading to an increase in the intracellular levels of specific proteins, including the cyclin-dependent kinase inhibitor, p21. Moreover, exposure of such cells to PS-341 caused them to accumulate in the G2-M phase of the cell cycle and subsequently undergo apoptosis, as indicated by nuclear condensation and poly(ADP-ribose) polymerase cleavage. Following weekly i.v. treatment of PS-341 to mice bearing the PC-3 tumor, a significant decrease (60%) in tumor burden was observed in vivo. Direct injection of PS-341 into the tumor also caused a substantial (70%) decrease in tumor volume with 40% of the drug-treated mice having no detectable tumors at the end of the study. Studies also revealed that i.v. administration of PS-341 resulted in a rapid and widespread distribution of PS-341, with highest levels identified in the liver and gastrointestinal tract and lowest levels in the skin and muscle. Modest levels were found in the prostate, whereas there was no apparent penetration of the central nervous system. An assay to follow the biological activity of the PS-341 was established and used to determine temporal drug activity as well as its ability to penetrate tissues. As such, PS-341 was shown to penetrate PC-3 tumors and inhibit intracellular proteasome activity 1.0 h after i.v. dosing. These data illustrate that PS-341 not only reaches its biological target but has a direct effect on its biochemical target, the proteasome. Importantly, the data show that inhibition of this target site by PS-341 results in reduced tumor growth in murine tumor models. Together, the results highlight that the proteasome is a novel biochemical target and that inhibitors such as PS-341 represent a unique class of antitumor agents. PS-341 is currently under clinical evaluation for advanced cancers.

Algorithms↗
PubMed1999

Inhibition of NF-kappa B activation in vitro and in vivo: role of 26S proteasome.

It is becoming increasingly apparent that NF-kappa B plays a critical role in regulating the inflammatory response. Data obtained from studies in our laboratories demonstrate that the proteasome plays an important role in the inflammatory cascade by regulating the activation of NF-kappa B. Indeed, the availability of selective and orally active proteasome inhibitors should prove useful in delineating the roles of the proteasome and NF-kappa B in other pathophysiological conditions such as cancer and heart disease.

Acetylcysteine↗
PubMed1998

Role of the proteasome and NF-kappaB in streptococcal cell wall-induced polyarthritis.

The transcription factor NF-kappaB activates a number of genes whose protein products are proinflammatory. In quiescent cells, NF-kappaB exists in a latent form and is activated via a signal-dependent proteolytic mechanism in which the inhibitory protein IkappaB is degraded by the ubiquitin-proteasome pathway. Consequently, inhibition of the proteasome suppresses activation of NF-kappaB. This suppression should therefore decrease transcription of many genes encoding proinflammatory proteins and should ultimately have an anti-inflammatory effect. To this end, a series of peptide boronic acid inhibitors of the proteasome, exemplified herein by PS-341, were developed. The proteasome is the large multimeric protease that catalyzes the final proteolytic step of the ubiquitin-proteasome pathway. PS-341, a potent, competitive inhibitor of the proteasome, readily entered cells and inhibited the activation of NF-kappaB and the subsequent transcription of genes that are regulated by NF-kappaB. Significantly, PS-341 displayed similar effects in vivo. Oral administration of PS-341 had anti-inflammatory effects in a model of Streptococcal cell wall-induced polyarthritis and liver inflammation in rats. The attenuation of inflammation in this model was associated with an inhibition of IkappaBalpha degradation and NF-kappaB-dependent gene expression. These experiments clearly demonstrate that the ubiquitin-proteasome pathway and NF-kappaB play important roles in regulating chronic inflammation and that, as predicted, proteasome inhibition has an anti-inflammatory effect.

Animals↗
PubMed1990

Expression of Mycobacterium tuberculosis and Mycobacterium leprae proteins by vaccinia virus.

Eight Mycobacterium tuberculosis and M. leprae genes were inserted into the vaccinia virus genome by in vivo recombination. The resulting virus recombinants were shown to express five different M. tuberculosis proteins (71, 65, 35, 19, and 12 kDa) and three M. leprae proteins (65 and 18 kDa and a biotin-binding protein) by Western immunoblot analysis, radioimmunoprecipitation, or black-plaque assay. When injected into BALB/c mice, the recombinants expressing the M. tuberculosis 71-, 65-, or 35-kDa protein and the M. leprae 65-kDa protein or the biotin-binding protein elicited antibodies against the appropriate M. tuberculosis or M. leprae protein. These vaccinia virus recombinants are being tested for the ability to elicit immune protection against M. tuberculosis or M. leprae challenge in animal model systems. The recombinants are also useful in generating target cells for assays aimed at elucidating the cellular immune responses to mycobacterial proteins in leprosy and tuberculosis. Furthermore, the M. tuberculosis 65-kDa protein and four of the other mycobacterial proteins share homology with known eucaryotic and procaryotic stress proteins, some of which may play a role in autoimmunity.

Animals↗
PubMed1990

Generation of hybrid genes and proteins by vaccinia virus-mediated recombination: application to human immunodeficiency virus type 1 env.

The ability of poxviruses to undergo intramolecular recombination within tandemly arranged homologous sequences can be used to generate chimeric genes and proteins. Genes containing regions of nucleotide homology will recombine to yield a single sequence composed of portions of both original genes. A recombinant virus containing two genes with a number of conserved regions will yield a population of recombinant viruses containing a spectrum of hybrid sequences derived by recombination between the original genes. This scheme has been used to generate hybrid human immunodeficiency virus type 1 env genes. Recombinant vaccinia viruses that contain two divergent env genes in tandem array have been constructed. In the absence of selective pressure to maintain both genes, recombination between conserved homologous regions in these genes generated a wide range of progeny, each of which expressed a novel variant polypeptide encoded by the newly created hybrid env gene. Poxvirus-mediated recombination may be applied to map type-specific epitopes, to create novel pharmaceuticals such as hybrid interferons, to study receptor-binding or enzyme substrate specificities, or to mimic the antigenic diversity found in numerous pathogens.

Animals↗
PubMed1987

Effective tumor immunotherapy directed against an oncogene-encoded product using a vaccinia virus vector.

We have constructed a vaccinia virus recombinant that expresses the extracellular domain of the rat neu oncogene-encoded protein, a 185-kDa transmembrane glycoprotein termed p185. Strain NFS mice immunized with this recombinant virus developed a strong antibody response against the neu oncogene product and were fully protected against subsequent tumor challenge with neu-transformed NIH 3T3 cells. No tumor immunoprotection was found when recombinant virus-immunized mice were challenged with Ha-ras-transformed NIH 3T3 cells. These data indicate that immunization with a single oncogene-encoded antigen can fully and specifically protect animals against tumor cells bearing this antigen.

Animals↗
PubMed1978

LETS glycoprotein: arrangement and function at the cell surface.

LETS is a large surface glycoprotein that is found on normal fibroblasts, but is absent or exists in amounts on transformed cells. Immunofluorescent staining shows LETS protein fibrils arrayed around the cells, particularly concentrated beneath the cells and in the area between neighboring cells. LETS glycoprotein is disulfide-bonded at the cell surface into dimers and higher aggregates. Other surface proteins also appear to participate in disulfide bonding. Reduction of disulfide bonds leads to increased release of LETS protein from the cells, as does the addition of cytochalasin B. Purified LETS protein added to transformed cells binds to the cells in a fibrillar array similar to that seen on normal cells. Addition of LETS protein leads to increased attachment and spreading of cells and causes transformed cells to align like normal ones. It also causes the appearance of actin cables in transformed cells, which normally lack them. These effects are inhibited by specific antisera to LETS protein or by reduction of disulfide bonds in the protein and are blocked or reversed by proteolysis. The results suggest that LETS protein plays a role in adhesion of cells.

Actins↗
PubMed1977

Extensive disulfide bonding at the mammalian cell surface.

Cell surface proteins of cultured cells are disulfide bonded to a greater degree than are total cellular proteins. In particular, the "large external transformation-sensitive" (LETS) protein, a major surface protein, is present almost exclusively in disulfide-bonded complexes including homodimers and also higher aggregates held together by disulfide bonds or concovalent interactions. Other cell surface proteins also appear to be involved in disulfide bonding, both intramolecular and intermolecular. In virally transformed cells, LETS protein and its disulfide complexes are absent and certain other disulfide-bonded proteins are also not observed.

Cell Line↗
PubMed1967

Genetic control of lactate dehydrogenase formation in the hagfish Eptatretus stoutii.

The isozyme patterns of lactate dehydrogenases of various tissues were studied on 51 hagfish by starch-gel electrophoresis. Nine lactate dehydrogenase phenotypes were encountered, suggesting the coexistence of two alleles at each of the two separate gene loci. There apparently was no interaction between the products of these two separate loci. Even the products of two alleles at the same locus were apparently incapable of forming hybrid molecules, an indication of the possible monomeric nature of each lactate dehydrogenase molecule.

Animals↗