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Biomedical subjects

L H Kedes

Publications and source records attributed to L H Kedes.

At least 19 recordsLinked to original sources
PubMed1996

Transplantation of fetal myocardial tissue into the infarcted myocardium of rat. A potential method for repair of infarcted myocardium?

BACKGROUND: Unlike skeletal myocytes, mammalian adult cardiomyocytes cannot regenerate after injury. A possible strategy to increase viability and augment ventricular function after myocardial injury is fetal myocardial tissue transplantation. The engrafted fetal cells are a potential source of growth factors and can be used for cardiomyocyte-based gene therapy. The purpose of our study was to test the feasibility and efficiency of fetal cardiomyocyte transplantation into a model of myocardial infarction. METHODS AND RESULTS: We subjected rats after myocardial infarction to three protocols of therapy. In the first protocol, tissue fragments of cultured human fetal ventricles were injected into the scar 7 to 24 days after infarction. The rats were treated with intraperitoneal injections of 12.5 mg.kg-1.d-1 cyclosporine. In the second protocol, fragments of cultured fetal rat ventricles were injected into the scar 9 to 17 days after infarction. A third group of animals with myocardial infarction was treated with injection of saline into the scar (control). After 7 to 65 days post-transplantation, hearts were harvested and processed for electron microscopy and alpha-actin immunohistochemistry. Toluidine blue staining and electron microscopy revealed the presence of engrafted human and rat cardiomyocytes in the infarcted myocardium up to 14 and 65 days after transplantation, respectively. The morphology was similar to that of cultured fetal cardiomyocytes. The engrafted fetal tissues were also stained positive for alpha-actin, which is unusual for the adult rat myocardium. Examination of control hearts detected infarcted tissue only, and alpha-actin staining was limited to vessel walls. CONCLUSIONS: Fetal cardiomyocyte tissue can be implanted and survive in the infarcted myocardium. This experimental approach may provide a therapeutic strategy for cardiomyocyte-based gene therapy for introduction of therapeutic proteins into myocardial infarction.

Actins↗
PubMed1986

BIONET: national computer resource for molecular biology.

This paper describes briefly the BIONET National Computer Resource for Molecular Biology. This presentation is intended as information for scientists in molecular biology and related disciplines who require access to computational methods for sequence analysis. We describe the goals, and the service and research opportunities offered to the community by BIONET, the relationship of BIONET to other national and regional resources, our recent efforts toward distribution of the resource to BIONET Satellites, and procedures for investigators to gain access to the Resource.

Amino Acid Sequence↗
PubMed1986

Human homologs of TU transposon sequences: polypurine/polypyrimidine sequence elements that can alter DNA conformation in vitro and in vivo.

We previously have shown that homologs of the outer domain segment of the inverted repeat termini (IVR-OD) of the sea urchin TU transposons are conserved among multiple eucaryotic species, including humans. We report here that two cloned human DNA IVR-OD homologs, Hut2 and Hut17, consist of a series of tandem repeats of the trimer AGG/TCC, forming segments (313 and 221 base pairs in length, respectively) of polypurine/polypyrimidine (pPu/pPy or "Puppy") asymmetry in the two DNA strands; these are punctuated at certain sites with variant trimers, which are different for the two clones. Sequences homologous to the Hut2 pPu/pPy tract exist at multiple sites in the DNA of a wide variety of eucaryotes. Hybridization of human DNA with a Hut2 probe or with a previously described chicken DNA pPu/pPy sequence indicates that pPu/pPy sequences can be grouped into families distinguishable by the extent of their homology with each probe at different hybridization stringencies. Moreover, particular pPu/pPy tracts show species-specific differences in their distribution. Both the Hut2 and Hut17 pPu/pPy tracts are cleaved by S1 nuclease when tested on supercoiled plasmids. Most if not all of the 313-base-pair Hut2 pPu/pPy tract is also sensitive to S1 in its native location in HeLa cell chromatin, indicating that the sequence contains conformational information that can be expressed in vivo. This view is supported by evidence that exogenously derived Hut2 pPu/pPy tracts introduced into mouse L cells and integrated in chromatin can assume an S1-sensitive conformation.

Animals↗
PubMed1985

TU elements: a heterogeneous family of modularly structured eucaryotic transposons.

We describe here a family of foldback transposons found in the genome of the higher eucaryote, the sea urchin Strongylocentrotus purpuratus. Two major classes of TU elements have been identified by analysis of genomic DNA and TU element clones. One class consists of largely similar elements with long terminal inverted repeats (IVRs) containing outer and inner domains and sharing a common middle segment that can undergo deletions. Some of these elements contain insertions. The second class is highly heterogeneous, with many different middle segments nonhomologous to those of the first-class and variable-sized inverted repeats that contain only an outer domain. The middle and insertion segments of both classes carry sequences that also are found unassociated from the inverted repeats at many other genomic locations. We conclude that the TU elements are modular structures composed of inverted repeats plus other sequence domains that are themselves members of different families of dispersed repetitive sequences. Such modular elements may have a role in the dispersion and rearrangement of genomic DNA segments.

Animals↗
PubMed1982

SEQ: a nucleotide sequence analysis and recombination system.

SEQ is an interactive, self-documenting computer program that contains procedures for the analysis of nucleotide sequences and the manipulation of such sequences to allow the simulation and prediction of the results of recombinant DNA experiments.

Amino Acid Sequence↗
PubMed1981

Isolation of two clusters of mouse histone genes.

Histone mRNA was partially purified from mouse myeloma cells synchronized in S phase by isoleucine starvation. A cDNA was prepared that contained sequences complementary to all five mouse histone genes. This cDNA was used to screen a library of mouse DNA in lambda phage. The positive clones were screened by hybridization with sea urchin histone gene-specific probes to identify those clones that contained histone genes. Confirmation of this identification was obtained by hybridization with Drosophila histone genes. Two independent clusters of histone genes were isolated. One, MM531, contains regions hybridizing specifically to H3, H4, and H1 and the other, MM221, contains two regions hybridizing specifically to H3 and single regions complementary to H4, H2b, and H2a. They are not part of a simple repeating structure. The nucleotide sequence of the coding region of the H3 gene in MM531 has been determined. This gene could code for a variant H3 protein that has several amino acid substitutions not reported in other H3 proteins.

Animals↗
PubMed1980

Leader sequences of Strongylocentrotus purpuratus histone mRNAs start at a unique heptanucleotide common to all five histone genes.

We have determined the sequence of the untranslated leader nucleotides of all five histone mRNAs from Strongylocentrotus purpuratus by the dideoxy chain termination method. Total polysomal RNA from sea urchin embryos was used as a substrate for cDNA synthesis primed by specific DNA restriction fragments. Each of the primers was derived from the 5'-terminal part of the coding region for a different histone protein. The five histone mRNA leader sequences are different in length and primary structure. The 5' termini of all five histone mRNAs coincide with the unique heptanucleotide Py-Py-A-T-T-C-Pu in genomic DNA. This sequence, which defines the start of the individual histone mRNAs, is preceded by the A+T-rich octanucleotide identified in front of all eukaryotic structural genes where sequences have been determined to date.

Animals↗
PubMed1979

Rapid purification of biologically active individual histone messenger RNAs by hybridization to cloned DNA linked to cellulose.

We describe a rapid and simple method for the purification of biologically active messenger RNAs. The method allows the isolation in a few hours of specific mRNAs from either whole cell or polysomal RNA even if the RNA represents less than 1% of the starting molecules. We used, as a model, cloned sea urchin (Strongylocentrotus purpuratus) histone gene fragments linked to cellulose by the method of B. E. Noyes & G. R. Stark (1975) Cell 5, 301--310) as hybridization probes to isolate specific histone mRNAs from whole cell and polysomal RNA extracts. RNAs isolated in this manner maintain their biological activity, serving as templates for histone proteins in a wheat-germ, cell-free protein translation system. In addition, radiolabeled histone-specific RNA purified from cleavage stage sea urchin embryos, pulse labeled for short periods of time and analyzed on denaturing polyacrylamide gels, was the same size as mature histone mRNA's.

Animals↗
PubMed1979

Nonallelic histone gene clusters of individual sea urchins (Lytechinus pictus): polarity and gene organization.

We have analyzed the histone genes from the sea urchin Lytechinus pictus. Examination of native DNA from individuals reveals four major Eco RI restriction endonuclease histone gene DNA fragments which have been labeled A (6.0 kb), B (4.1 kb), C (3.1kb) and D (1.2 kb). The fragments A, B and C have been cloned into E. coli plasmids (pLpA, pLpB and pLpC). These histone gene fragments display length and sequence heterogeneity in different individuals. The plasmid pLpA contains the coding regions for H1, H4, H2B and H3 histones, and we determined that the DNA fragment D is tandem to A in native DNA and that it contains the H2A gene. The plasmids pLpB and pLpC contain the histone genes H2A-H1-H4 and H2B-H3, respectively, and together contain the sequences for the five major histones. Restriction analysis of native L. pictus DNA reveals that B and C are tandem to each other but not intermingled with the A--D-type repeat units, and are thus in separate clusters with a repeat length of 7.2 kb. Since the two cluster types do not segregate, they are not alleles. Hybridization of histone mRNA to exonuclease III-digested linear DNA demonstrated an identical polarity of the histone genes in the A--D- and B--C-type repeat units. This result revealed that the L. pictus histone genes have a polarity which is the same as other sea urchin histone genes examined to date--that is, 3' H1-H4-H2B-H3-H2A 5'. Restriction endonuclease cleavage patterns of the cloned segments indicate that considerable sequence heterogeneity exists between the two types of histone gene repeat units.

Animals↗
PubMed1979

Nonallelic histone gene clusters of individual sea urchins (Lytechinus pictus): mapping of homologies in coding and spacer DNA.

The linear arrangement and lengths of the spacers and coding regions in the two nonallelic histone gene variant clusters of L. pictus are remarkably homologous by R loop analysis and are similar in general topography to the histone gene repeat units of other sea urchins examined to date. No interventing sequences were detected. The coding regions of these two histone gene variants share considerable sequence homology; however, there are areas of nonhomology in every spacer region and the lengths of the nonhomologous spacers between the H2A and H1 genes are not the same for the two repeat unit classes (inter-gene heterogeneity). Combining length measurements obtained with both R loops and heteroduplexes suggests that the DNA sequences of the analogous leader regions for the two H1 mRNAs are nonhomologous. Similar observations were made for the H4 leader sequences, as well as the trailer region on H2B. S. purpuratus spacer DNA segments share little sequence homology with L. pictus; however, the analgous coding (and possibly flanking) regions have conserved their sequences. The various coding and spacer regions within a repeat unit do not share DNA sequences. Thus certain areas in the sea urchin histone gene repeat units have been highly conserved during evolution, while other areas have been allowed to undergo considerable sequence change not only between species but within a species.

Animals↗
PubMed1978

Decreased ribosomal RNA content and in vitro RNA synthesis in purified bone marrow erythroblasts of patients with idiopathic ineffective erythropoiesis and DiGuglielmo disease.

Ribsomal RNA content and in vitro 3H-uridine and 3H-thymidine incorporation with examined in purified marrow erythroblasts of patients with idiopathic ineffective erythropoiesis (IIE) and DiGuglielmo disease (DD) and compared with cells from normal marrows. Whereas 3H-thymidine incorporation rates were normal in all patients, 3H-uridine incorporation was 42%--75% of normal in cells from patients examined. Ribosomal RNA content was measured by spectrophotometric scanning of RNA electrophoresed on polyacrylamide gels and corrections made for contamination of the erythroblast preparations with ribosome bearing reticulocytes. In cells from every patient examined RNA content was decreased to 60--76% of normal. Uridine incorporation and rRNA content of patients with beta thalassemia minor and megaloblastic anemia were normal, suggesting that the defects observed in IIE and DD were not due to ineffective erythropoiesis per se. Since erythroblast ribosomes may be rate limiting in protein synthesis, we postulate that even a minor decrease in ribosome content might engender the ubiquitous abnormalities reported in erythroid cells in both IIE and DD.

Bone Marrow Cells↗
PubMed1978

The DNA sequence of sea urchin (S. purpuratus) H2A, H2B and H3 histone coding and spacer regions.

The DNA sequence of two cloned segments of the histone gene repeat unit of the sea urchin S. purpuratus has been determined. One sequence contains the contiguous H2B and H3 genes and their interdigitated spacer regions; the other comprises the H2A gene and flanking spacer sequences. Analysis of the coding regions reveals a methionine residue within the H2A protein. H2A, which generally lacks this amino acid, contains methionine only in a protein variant which is synthesized in early sea urchin embryogenesis. We thus conclude that the cloned DNA represents a set of genes which is active early in development. Codon selection is markedly skewed and similar for each of the three genes. The DNA sequences are co-linear with known histone protein sequences and-unlike several other eucaryotic genes-do not show any insertions in the coding regions. The spacer regions are relatively AT-rich although GC cluster are scattered throughout. Several short stretches of homology are found in regions both upstream and downstream from the protein coding segments. The conservation of these sequences and their location at analogous sites suggest that they are involved in gene transcription or in mRNA translation. No tandem or dispersed repeats were found, with the exception of the remarkable sequence having the structure located in the spacer between the H2A and H1 genes.

Animals↗