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J Závada

Publications and source records attributed to J Závada.

At least 19 recordsLinked to original sources
PubMed2001

General approach to the synthesis of persubstituted hydrophilic and amphiphilic beta-cyclodextrin derivatives.

Heptakis(2,3,6-tri-O-allyl)-beta-cyclodextrin 2 was converted to heptakis[2,3,6-tri-O-(2,3-dihydroxypropyl)]-beta-cyclodextrin 3 by osmium tetroxide-catalyzed dihydroxylation. A diastereomeric mixture of 3 was treated with sodium periodate followed by sodium borohydride to give heptakis[2,3,6-tri-O-(2-hydroxyethyl)]-beta-cyclodextrin 5 in 86% yield. Compound 5 could be quantitatively transformed into heptakis(2,3,6-tri-O-carboxymethyl)-beta-cyclodextrin 6 by TEMPO-mediated oxidation. The same reaction sequence was also applied to heptakis(2,6-di-O-allyl-3-O-methyl)-beta-cyclodextrin 8, heptakis(2,3-di-O-allyl-6-O-methyl)-beta-cyclodextrin 12, and heptakis(2,3-di-O-allyl-6-O-butyl)-beta-cyclodextrin 16; the analogous corresponding hydroxyethyl and carboxymethyl derivatives were isolated in high yields. All products were proved to be chemically uniform.

Cyclodextrins↗
PubMed2000

Human tumour-associated cell adhesion protein MN/CA IX: identification of M75 epitope and of the region mediating cell adhesion.

MN/CA IX is a cell surface protein, strongly associated with several types of human carcinomas. It exerts activity of carbonic anhydrase and capacity of binding to cell surface receptors. In the present work, we used affinity purified MN/CA IX protein to demonstrate that the cells adhere to immobilized MN/CA IX and that the monoclonal antibody M75 abrogates cell attachment to MN/CA IX. Using synthetic oligopeptides, we identified M75 epitope and located it in the proteoglycan domain, which contains a sixfold tandem repeat of six amino acids GEEDLP. From phage display library of random heptapeptides we identified and chemically synthesized those which compete for the epitope with M75 and inhibit adhesion of cells to MN/CA IX. These heptapeptides might serve as lead compounds for drug design.

Amino Acid Sequence↗
PubMed1999

Identification of MaTu-MX agent as a new strain of lymphocytic choriomeningitis virus (LCMV) and serological indication of horizontal spread of LCMV in human population.

In this study we elucidated the molecular character of MaTu-MX, previously described as an unusual transmissible agent. Amino acid sequencing of peptides generated from a 58-kDa MX-related protein purified from MaTu human carcinoma cells allowed us to identify it as a nucleoprotein (NP) of lymphocytic choriomeningitis virus (LCMV). Northern blot analysis detected LCMV-specific RNAs in MaTu cells. Comparative immunoprecipitations showed cross-reactivity between NP of LCMV strain WE and MX NP. Using RT-PCR, we have cloned MX NP cDNA. According to sequence comparison, MX LCMV is as closely related to both LCMV strains WE and Armstrong as these strains are to one another. Based on this finding we propose that MX is a new strain of LCMV. We also showed that the stability of MX NP in MaTu cells is very high and that the virus is transmissible by cell-to-cell contact or by cell-free extract to human HeLa and monkey Vero cells, but not to human AGS, canine MDCK, mouse NIH 3T3, and hamster CHO cells. Finally, employing MX LCMV NP in immunoprecipitation and solid-phase radioimmunoassay, we found 37.5% prevalence of anti-LCMV antibodies in human sera, suggesting possible horizontal spread of the virus in the human population.

3T3 Cells↗
PubMed1996

Human MN/CA9 gene, a novel member of the carbonic anhydrase family: structure and exon to protein domain relationships.

We have isolated, sequenced, and characterized a human MN/CA9 gene. This gene is a novel member of the carbonic anhydrase (CA) family, which codes for widely distributed catalysts of the reversible conversion of carbon dioxide to carbonic acid. So far, MN/CA IX is the only tumor-associated CA isoenzyme. The entire genomic sequence of MN/CA9, including the 5'-flanking region, encompasses 10.9 kb. The coding sequence is divided into 11 exons, whose organization and relationships to predicted protein domains suggest that the gene arose by exon shuffling. Exon 1 encodes a signal peptide and a proteoglycan-related region. Exons 2-8 code for a CA domain with a highly conserved active site. The exon/intron pattern of the CA coding region is similar but not identical to other described animal kingdom alpha-CA genes. Exons 10 and 11 encode a transmembrane anchor and an intracytoplasmic tail, respectively. We have also determined the transcription initiation and termination sites by RNase protection assay and analyzed the 3. 5-kb region upstream of the MN/CA9 gene. Sequence of the proximate 5' end of the flanking region shows extensive homology to the long terminal repeats of HERV-K endogenous retroviruses. The putative MN/CA9 promoter immediately preceding the transcription start site does not possess a TATA box, but contains consensus sequences for the AP1, AP2, p53, and Inr transcription factors. This study will allow further investigations of the molecular events regulating expression of MN/CA IX as well as elucidation of its biological function.

Amino Acid Sequence↗
PubMed1994

Identification of the MN antigen as a diagnostic biomarker of cervical intraepithelial squamous and glandular neoplasia and cervical carcinomas.

A new tumor-associated antigen, MN, has been identified whose expression correlates with the tumorigenic phenotype of HeLa x fibroblast somatic cell hybrids. Because HeLa is a cell line derived from a cervical carcinoma, we investigated the diagnostic utility of MN expression in cervical neoplasia. It was found that normal cervical tissue does not express the antigen, or does so in occasional focal areas of weakly staining reserve cells. In contrast, significant immunoreactivity (immunoperoxidase staining of paraffin-embedded sections) was observed in cervical intraepithelial neoplasias, adenocarcinoma in situ, and frank carcinomas, both squamous cell and adenocarcinoma. Varying patterns of immunoreactivity were observed and were characterized as diffuse, diffuse/focal, or focal. Greater than 90% of dysplastic or malignant tissues showed immunoreactivity. An interesting observation was that normal cervical tissue associated with cervical intraepithelial neoplasias, or adenocarcinoma in situ showed a staining pattern in the reserve cells and/or normal columnar cells that approximated the level of intensity exhibited by the dysplastic tissue. These results indicate that MN antigen expression has potential utility as a biomarker of cervical neoplasms.

Adenocarcinoma↗
PubMed1993

Expression of MaTu-MN protein in human tumor cultures and in clinical specimens.

MaTu is a novel agent which may be of relevance in human oncogenesis, and has 2 components. One of them, the exogenous MX (coding for protein p58X), is transmissible to human fibroblasts, to HeLa and to HeLa x fibroblast (H/F) hybrids. The other component, MN, is a cellular gene. Its product, the protein p54/58N, is inducible by infecting HeLa cells with MX or by growing them in dense cultures. This p54/58N appears to be a tumor-associated antigen: it is expressed in HeLa and in tumorigenic cells (H/F-T), but not in fibroblasts or in nontumorigenic hybrid cells (H/F-N). Proteins related to p54/58N were also found on immunoblots prepared from human carcinomas of ovary, endometrium and uterine cervix, but not from normal tissues from corresponding organs or from placenta. Using genetically engineered MN protein, we developed a radioimmunoassay for MN-specific antibodies, and for quantitative determination of MN proteins in cell extracts. In HeLa cells infected with MX we observed conspicuous ultrastructural alterations: formation of abundant filaments on the cell surface and amplification of mitochondria. Using immunogold-staining, we visualized the p54/58N on the surface microvilli and in the nucleus, particularly in nucleoli.

Animals↗
PubMed1992

A novel quasi-viral agent, MaTu, is a two-component system.

MaTu is a quasi-viral agent presumably derived from a human mammary tumor. In some respects it resembles classical viruses and in some the "slow viruses," and in others it is different from both. Using monoclonal antibodies (Mabs), we showed that it is a two-component system. One part of the complex, MX, is exogenous; it is manifested by a protein, p58X, which is a cytoplasmic antigen and it reacts with some natural sera of man and of various animals. The other component, MN, is endogenous to human cells. This is manifested by a twin protein(s), p54/58N, localized on the cell surface and in the nucleus. This protein is absent in rapidly growing, sparse cultures of HeLa, but it is inducible either by keeping the cells in dense cultures or, more efficiently, by infecting them with MX. Both inducing factors are synergistic. Only p54/58N is associated with virions of vesicular stomatitis virus (VSV), reproduced in MaTu-infected HeLa. This suggests that MN is responsible for complementation of VSV mutants and for the formation of the VSV (MaTu) pseudotype. Both p54/58N peptides are glycosylated and they form oligomers linked by disulfidic bonds; p58X is not glycosylated and it does not form S-S-linked oligomers.

Antibodies, Monoclonal↗
PubMed1991

An unusual transmissible agent--MaTu.

MaTu is an agent, believed to be derived from a human mammary carcinoma, which displayed several extraordinary properties. These were: RIP and PAGE revealed in MaTu-infected cells only a single protein band of Mr 58 k, the gp 58. This gp 58 was immunoprecipitated by antibodies present in some human sera as well as in some sera of rabbits, sheep, and cattle. MaTu had an extremely restricted host range: it was transmissible only to HeLa cells, but not to human embryo fibroblasts, to three human tumour cell lines (T 47 D, T 24, and HMB 2) or to monkey Vero and rabbit SIRC cells. A retrovirus with a broad host range, used as a helper (X-MLV) enabled the transmission of MaTu to human fibroblasts, but not to Vero or SIRC, which are also permissive for X-MLV. These observations, together with our previous reports, support the view that MaTu might either be a novel type of defective virus, or even a non-viral autonomous genetic element.

Animals↗
PubMed1988

Rescued human virus (RHV): association with melanoma.

RHV, which is presumably a defective human retrovirus, has been recovered from the human melanoma cell line HMB2. In the presence of Moloney mouse leukemia virus (MLV), used as a helper, RHV is serially transmissible in mouse NIH-3T3 cells and can provide envelope antigens for vesicular stomatitis virus pseudotype--VSV(RHV). This pseudotype is neutralizable with an inhibitor, present in all human sera tested; the inhibitory activity is resistant to heating at 100 degrees C. To detect whether any specific response to RHV is connected with the disease, we isolated IgG from 140 human sera (70 melanoma patients and 70 control group donors) and tested it for neutralization of VSV(RHV) pseudotype in a randomized, blind experiment. Sixteen samples of IgG from the sera of melanoma patients, but only one control IgG, neutralized the pseudotype; this difference was significant (p less than 0.001). RHV thus appears to be in some way associated with melanoma.

Defective Viruses↗
PubMed1986

Rescue of presumptive viral information from human cells by a helper oncovirus.

We have attempted to rescue presumptive human endogenous retrovirus(es) by using a competent animal oncovirus as a helper. Human melanoma cells (line HMB2) were fused, using polyethylene glycol, with mouse NIH-3T3 cells which had been infected and transformed by the Harvey murine leukaemia and sarcoma virus complex (MLV and MSV). The heteropolykaryons obtained were co-cultivated with fresh NIH-3T3 cells; filtered (Millipore 0.22 micron) medium from these was used to infect further NIH-3T3 cells. In these cells after several passages, vesicular stomatitis virus (VSV) pseudotypes could be produced. These were infectious not only for mouse cells (manifesting the helper MLV), but also for human cells (HeLa, HEC human embryo fibroblasts, HMB2); they were not infectious for CCL64 (mink) or for Vero (African green monkey) cells. The presence of such VSV pseudotypes infectious for human cells indicated that a human ecotropic virus [provisionally named rescued human virus (RHV)] had been rescued by the fusion of human melanoma cells with MLV-infected mouse cells. This was supported by the following evidence. The human-specific pseudotype was neutralized by sheep antisera raised to antigens selected by VSV from human tumour cell lines HMB2, T47D and HeLa. These antisera also aggregated NIH cells infected with MLV and RHV. Mouse antisera raised to antigens present in HIH cells infected with MLV and RHV, in contrast to sera raised to NIH cells infected with MLV only, immunoprecipitated an 85,000 mol. wt. protein band from human cells (HEC, HMB2 and HeLa) surface-labelled with 125I.

Animals↗
PubMed1984

Further characterization of proteins assembled by vesicular stomatitis virus from human tumor cells.

Vesicular stomatitis virus (VSV), when reproduced in human tumor cell lines, assembled a specific subset of cell-derived proteins. These were detected by 35S]methionine labeling of cells prior to infection and subsequent immunoprecipitation of VSV grown in these cells, as well as by direct immunoprecipitation of labeled cell extracts with antiserum directed against the VSV-assembled proteins. Their molecular weight (Mr) ranged between 15K and 180K; the larger proteins were glycosylated. Two of the major protein species (gp88 and gp130) were common to all four cell lines used (HeLa-cervical carcinoma, T47D-breast carcinoma, and HMB2 and SK1477-two melanoma cell lines). Proteins of other molecular weights were detected only in one or two of the cell lines. The melanoma cell lines (even in the absence of VSV) shed large particulate material which had contained the same spectrum of proteins that were assembled by VSV. The major protein component had an Mr of 30K. Some of the VSV-assembled proteins might possibly serve as specific tumor markers. It is also conceivable that the proteins assembled by VSV as well as the large particulate material might be products of defective endogenous human retroviruses.

Breast Neoplasms↗
PubMed1984

Monoclonal antibody against an antigen selectively assembled into vesicular stomatitis virus virions from HeLa cells.

A mouse hybridoma cell line IIB9, secreting IgG2b antibody specific for a HeLa cell antigen, was obtained by fusion of a mouse myeloma cell line with spleen cells from mice immunized with purified VSV tsO45 mutant (defective in assembly of G protein) which had been reproduced at a non-permissive temperature in HeLa cells. The monoclonal antibody IIB9 was strictly specific for HeLa cells in two tests: (1) reaction with VSV or Chandipura virus phenotypically mixed with host cell antigen, (2) complement-dependent cytotoxicity test (51Cr-release).

Antibodies, Monoclonal↗
PubMed1983

Human cell surface proteins selectively assembled into vesicular stomatitis virus virions.

Vesicular stomatitis virus (VSV) selectively assembled proteins from human cells into progeny virions. These proteins can be surface labeled before infection with 125I, and when purified virus was examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, only two or three bands of proteins (Mr around 100K) were seen. Antisera to these proteins were produced, using as immunizing antigen VSV tsO45 mutant, defective in assembly of G protein, which had been made at the nonpermissive temperature in the three human tumor cell lines, HeLa (cervical carcinoma), T47D (breast carcinoma), and HMB2 (melanoma). After absorption with wild-type VSV, each of the antisera displayed a different pattern of reactivity; at least three antigenic specificities were detected. Two of them, corresponding to antigens selected by VSV from HeLa and T47D, were to some extent related and they showed an association mainly with epithelial cell-derived gynecological tumors, but they were absent in carcinomas of lung or of digestive tract. These (or related) antigens were expressed in a lower level in some normal tissues, mainly in ovaries. Antigen(s) assembled by VSV from the melanoma cell line was entirely different and appeared to be associated with cell growth. The grounds for selective assembly of these specific proteins by VSV are not clear; they either share with viral surface glycoproteins some physical or structural properties, which are critical for incorporation into the viral envelope, or conceivably they even may represent uncleaved precursor proteins coded by env genes of incomplete genomes of endogenous human retroviruses.

Antigens, Neoplasm↗
PubMed1983

Specific selection of host cell glycoproteins during assembly of murine leukaemia virus and vesicular stomatitis virus: presence of Thy-1 glycoprotein and absence of H-2, Pgp-1 and T-200 glycoproteins on the envelopes of these virus particles.

Using the indirect immunoelectron microscopy technique, it was investigated whether during assembly of murine leukaemia virus (MuLV) and vesicular stomatitis virus (VSV), the glycoproteins (gp) Thy-1, H-2, Pgp-1 and T-200 present on the surface of BW5147 and BuEL4 leukaemia cell lines were incorporated into the virus envelopes. This work was done mainly with monoclonal antibodies against these gps to exclude the presence of antibodies against endogenous MuLV present in conventional mouse antisera. Thy-1 gps were incorporated into MuLV and VSV envelopes. In contrast, H-2, Pgp-1 and T-200 gps were excluded from the budding of both virus particles. To study whether the presence of Thy-1 gps on the viral envelopes is due to some lateral affinity of this molecule with viral gps, the physical association of Thy-1.1 antigens and MuLV antigens was studied with antibody-induced redistribution of both antigens on the BW5147 cell surface. Antibody-induced patching of the viral antigens did not result in co-patching of the Thy-1.1 antigens. In the reciprocal tests no co-redistribution of viral antigens with Thy-1.1 antigens was seen. These studies show that the presence of Thy-1.1 gp on the MuLV envelope cannot be due to a lateral affinity of this molecule with viral gps and that a selection of surface gps takes place during assembly of MuLV and VSV.

Animals↗
PubMed1983

Assembly of xenotropic murine leukaemia virus-related antigens from the surface of mouse L cells by vesicular stomatitis virus.

Two xenotropic murine leukaemia virus (XMuLV)-related proteins--a major envelope glycoprotein gp70 and a 90K protein (probably corresponding to the uncleaved envelope precursor)--were expressed on the surface of mouse L cells as demonstrated by lactoperoxidase-catalysed iodination and immunoprecipitation with anti-XMuLV serum. These two proteins out of many labelled cell surface proteins were selectively incorporated into vesicular stomatitis virus (VSV) virions. Significant differences were found in the amounts of labelled XMuLV-related proteins between L cells and two cell lines infected with XMuLV (rabbit SIRC and lamb LKC cells). The two viral antigens represented only a small proportion of radioactivity on L cells. While in XMuLV-infected SIRC and LKC cells, the gp70 was the major labelled surface protein no detectable amounts of XMuLV-related 90K protein or of cell-specific proteins were found in these cells.

Animals↗
PubMed1983

Vesicular stomatitis virus phenotypically mixed with retroviruses: an efficient detection method.

Two methods of assaying vesicular stomatitis virus (VSV) particles phenotypically mixed with retrovirus-coded antigens were compared. Each of them detected phenotypically mixed particles with different minimum proportion of surface glycoprotein molecules of the donor virus, and consequently also profoundly different proportions of VSV virions containing retrovirus antigens. Only a low proportion (10(-4) of VSV virions grown in XMuLV-infected rabbit SIRC cells behaved as pseudotypes, resistant to anti-VSV serum and neutralized by anti-XMuLV serum. VSV produced in mouse L cells did not contain significant titre of pseudotype particles in the neutralization test. However, when immunoprecipitation was used with corresponding antibody and Staphylococcus aureus cells, almost 100% of the VSV virions produced in L cells and in XMuLV-preinfected SIRC cells were found to contain MuLV-related antigen molecules.

Animals↗
PubMed1982

The pseudotypic paradox.

The assembly of virion surface glycoproteins by enveloped viruses appears to be both specific and non-specific. It is non-specific in the sense that, during a dual infection by various unrelated viruses, there is very common (if not universal) and efficient mixing of envelope glycoproteins from both genotypes in the progeny virions. However, it seems to be specific in the sense that non-viral, cell surface proteins are, in the main, recognized as alien and are excluded from incorporation into virions during budding. These findings suggest that all enveloped viruses may share an essentially common molecular mechanism for the specific assembly and budding of virus glycoproteins while at the same time incorporating a mechanism for the exclusion of glycoproteins of cellular origin. One of the simplest explanations for this phenomenon may be that virus envelope surface structures all evolved from a single ancestral virus.

Biological Evolution↗