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Biomedical subjects

M Rabinowitz

Publications and source records attributed to M Rabinowitz.

At least 37 records · Page 2Linked to original sources
PubMed1985

Home refinishing, lead paint, and infant blood lead levels.

We measured the blood lead levels of 249 infants semi-annually from birth to two years of age; we sampled the home paint and recorded any recent home refinishing activity. Mean blood lead from birth to age 2 years did not vary systematically with age but did correlate significantly with the amount of lead in the indoor paint (p less than .01). Refinishing activity in homes with high lead paint was associated with elevations of blood lead averaging 69 per cent.

Adult↗
PubMed1979

Transcription, processing, and mapping of mitochondrial RNA from grande and petite yeast.

Mitochondrial RNA (mtRNA) from petite yeast strains was analyzed by electrophoresis in agarose-urea, acrylamide-urea, and agarose-methyl mercuric hydroxide gels, and by transfer to diazobenzyloxy-methyl paper and hybridization to labeled mitochondrial DNA (mtDNA). Petites contain numerous mitochondrial transcripts, including processed species like 21 S and 14 S rRNA. Petite transcripts were found to fall into three classes: 1) bands that comigrate with grande mtRNA species; 2) "group-specific" new bands found in multiple strains and coinciding with specific regions of the mitochondrial genome; and 3) "strain-specific" new bands found only in individual petite strains. A deletion map was constructed in which we used the presence or absence of the first two types of mtRNA bands in specific strains, and the restriction endonuclease map of these strains. This map confirmed the localization of 21 S and 14 S rRNA, which were mapped previously by hybridization, and also localized more than 20 additional mtRNA species. The mtRNA species were grouped in regions of the genome in a fashion that strongly suggests that many of them are precursors to fully processed mtRNA species. Hybridization experiments with grande mtRNA and cloned mtDNA fragments have shown the same kind of transcript grouping. Other hybridization experiments have demonstrated two apparent precursors to 21 S rRNA (3700 nucleotides) measuring 5500 and 4500 nucleotides. Processed tRNAs are found only in petites that contain a specific region of the genome near the P (paromomycin resistance) locus. When this region is absent, processed tRNAs are not detected, even for tRNA genes quite distant from the P locus. Since this phenotype is expressed in petites that lack mitochondrial protein synthesis, and since it maps to a specific location in the mitochondrial genome, there appears to be a mtRNA species which has a role in processing of mitochondrial tRNA.

DNA, Mitochondrial↗
PubMed1979

Differential competition with cytotoxic agents: an approach to selectivity in cancer chemotherapy.

An approach to increasing the selectivity of cancer chemotherapeutic agents is presented in which noncytotoxic competitive substrates are used to discern the differences in structural requirements for transport of cytotoxic agents between tumor cells and a sensitive host tissue, the hematopoietic precursor cells of the bone marrow. Examples are given for two such systems, one responsible for the transport of nucleosides and another for the transport of amino acids. Cytidine is twice as effective in reducing the toxicity of showdomycin for murine bone marrow cells in culture as it is for murine L1210 leukemia cella. Conversely, homoleucine is twice as effective in reducing the toxicity of melphalan for L1210 cells as it is for bone marrow cells. These observations can serve as a basis for the development of bone marrow protective agents and for the design of cytotoxic agents that may be preferentially transported into tumor cells.

Animals↗
PubMed1979

Physical mapping of the Xba I, Hinc II, Bgl II, Xho I, Sst I, and Pvu II restriction endonuclease cleavage fragments of mitochondrial DNA of S. cerevisiae.

A detailed molecular dissection of the yeast mitochondrial genome can be made with restriction endonucleases that generate site-specific cuts in DNA. The ordering of restriction fragments provides the basis of the physical mapping of mitochondrial transcripts and antibiotic resistance (antR) loci, and is a means of analyzing the molecular organization of mtDNA of petite and mit- deletion mutants. We have previously mapped the sites in the mtDNA of yeast strain MH41-7B recognized by the endonucleases Eco RI, Hpa I, Hind III, Bam HI, Sal I, Pst I, and Hha I, providing a total of 41 cleavage sites. We have now mapped the sites recognized by the endonucleases Xba I, Hinc II, Bgl II, Pvu II, Xho I, and Sst I, which make 6, 13, 5, 6, 2, and 2 cuts, respectively. Fragment maps for each of these endonuclease sites were derived by analysis of the products of double-enzyme digests and by hybridization of 3H-cRNA probes transcribed from low-kinetic-complexity petite mtDNAs to restriction fragments generated by various combinations of enzymes.

Base Sequence↗
PubMed1979

Physical mapping of the yeast mitochondrial genome: derivation of the fine structure and gene map of strain D273-10B and comparison with a strain (MH41-7B) differing in genome size.

(1) We have derived a fine-structure map of the 70 kb mitochondrial genome of the yeast S. cerevisiae, strain D273-10B, and compared it with our previous maps for strain MH41-7B. Restriction fragment maps for 56 enzyme recognition sites for 13 endonucleases, Eco RI, Hpa I, Bam HI, Hha I, Hinc II, Xba I, Hind III, Bgl II, Pvu II, Sal I, Pst I, Sst I, and Xho I, have been derived. We have used several methods to obtain these maps: (a) Four enzymes (Sal I, Sst I, Xho I, Pst I), each of which cuts D273-10B mtDNA at a single site, were employed to localize and orient fragments from multi-site enzyme digests that are cleaved by the single-site enzyme. (b) Radioactively labeled probes (rRNA or copy RNA [cRNA] transcribed from simple-sequence petite mtDNA) were hybridized to restriction fragments from different digests for identification of fragments which share common sequences. (c) The products of double or triple enzyme digests were identified for mapping and confirmation of the localization of restriction sites. (2) The antibiotic-resistant (antR) loci for erythromycin (E), chloramphenicol (C), paromomycin (P), and oligomycin (OI, OII) were positioned on the physical restriction map by hybridization of 3H-labeled cRNA transcribed from simple-sequence petite mtDNAs that retain a single genetic antR marker to appropriate restriction fragments bound to nitrocellulose filters. (3) Mitochondrial transcripts (21s rRNA, 14s rRNA, and tRNAs) labeled with 125I were hybridized to restriction fragments for identification of the corresponding coding sequence. (4) The gene order and localization of the antR loci and mitochondrial transcripts are as follows: C(0-1.5u)-tRNA I(0-21.5u)-P(29-36.6u)-tRNA II(29-46.4u)-14s rRNA(36-38.3u)-OII(60.3-62.5u) - tRNA III(73-76u) - OI(78.6-83.0u) - tRNA IV(82.5-83.0u) - E(94.2-98.6u) - 21s rRNA (94.2-99.4u). (5) The DNA fine structure and gene map of the 70 kb D273-10B mtDNA were compared to the map of the larger MH41-7B (76 kb) mtDNA. There are 56 restriction sites on D273-10B and 67 sites on MH41-7B for the 13 enzymes studied. The additional restriction sites are largely accounted for by the presence, in MH41-7B, of two sets of sequences, "A" (2.7 kb) and "B" (3.0 kb), located on either side of the OII marker. The remainder of the fragments map is remarkably similar for the two strains. The distances separating the antR loci and the mitochondrial transcripts are very similar except in the two regions surrounding OII.

DNA Restriction Enzymes↗
PubMed1979

Propagation of restriction fragments from the mitochondrial DNA of Saccharomyces cerevisiae in E. coli by means of plasmid vectors.

Some of the EcoRI fragments of yeast (Saccharomyces cerevisiae) mitochondrial DNA were cloned into E. coli using plasmid pMB9. The five smallest fragments in molecular weight appeared to be preferentially retained by E coli; partial fragments derived from larger mitochondrial DNA fragments were also found. One of the fragments, R7 (2.4 kb), may contain the OII gene. Cloned R7 DNA was stable under a variety of growth conditions, but showed some changes in molecular weight after transfer to different E. coli strains. Fragment R7 is transcribed in minicells, producing RNA that hybridizes specifically to mitochondrial DNA. Both DNA strands are transcribed, in contrast to the asymmetric transcription found in mitochondria. No new polypeptides were observed in minicells containing cloned fragment 7.

DNA Restriction Enzymes↗
PubMed1979

Molecular aspects of cardiac hypertrophy.

Despite continuous interest in cardiac hypertrophy, our knowledge of its molecular aspects is still elementary. Recently, however, several advancements of particular interest have been made: (a) Nuclei of muscle and nonmuscle cells have been separated, allowing for the first time the study of nuclear activity in specified cells (18). (b) Cardiac growth induced by pressure-overload (72) or by hormone treatment (26) has been shown to lead to myosin of altered ATPase, and strong evidence suggests that new species of myosin molecules thus appear. (c) The basis for assessment of protein synthesis and degradation has been established (46, 48). (d) Methods are being developed to supplement radioautography in evaluating cell proliferation (42, 59, 69). (e) In spontaneously hypertensive rats it has been shown that blood pressure might not be the sole factor responsible for cardiac enlargement, but that hypertrophy can be the result of genetic cardiovascular abnormality (19, 66). (f) A hypothesis relating the extent of energy utilization to the nuclear activity via NAD+ metabolism has been proposed, which allows for experimental verification (43).

Adenosine Triphosphatases↗
PubMed1979

Changes in mitochondrial DNA in cardiac hypertrophy in the rat.

We studied DNA (mtDNA) replication in adult female rat hearts undergoing hypertrophy secondary to constriction of the ascending aorta. MtDNA was measured in isolated mitochondria by a fluorometric method adapted for that purpose. The conditions for removal of contaminating nuclear DNA were developed, and the purity of the mtDNA was assessed from its molecular conformation (open and closed circles) and by renaturation-kinetic analysis. The mtDNA concentration in mitochondria, expressed as micrograms of DNA per milligram of mitochondrial protein, increased 2, 4, and 7 days postoperatively by 21, 73, and 98%, respectively. Similar results were obtained when mtDNA was expressed per nonomole of cytochrome a. The population of replicative intermediates of mtDNA was analyzed by electron microscopy. In normal hearts, we observed molecular forms characteristic of animal mtDNA, such as circular monomers and dimers, catenated molecules, D-loops, expanded D-loops, and gapped molecules. D-loop frequency, which was near 50% in the mtDNA of control hearts, was markedly reduced to 5-7% in hypertrophying hearts. This result indicates that the increase in replicative flux of mtDNA is associated with the removal of a block in the conversion of D-loops to other intermediates.

Animals↗
PubMed1978

Physical mapping of genes on yeast mitochondrial DNA: localization of antibiotic resistance loci, and rRNA and tRNA genes.

We have physically mapped the loci conferring resistance to antibiotics that inhibit mitochondrial protein synthesis (erythromycin, chloramphenicol and paromomycin) or respiration (oligomycin I and II), as well as the 21s and 14s rRNA and tRNA genes on the restriction map of the mitochondrial genome of the yeast Saccharomyces cerevisiae. The mitochondrial genes were localized by hybridization of labeled RNA probes to restriction fragments of grande (strain MH41-7B) mitochondrial DNA (mtDNA) generated by endonucleases EcoRI, HpaI, BamHI, HindIII, SalI, PstI and HhaI. We have derived the HhaI restriction fragment map of MH41-7B mit DNA, to be added to our previously reported maps for the six other endonucleases. The antibiotic resistance loci (antR) were mapped by hybridization of 3H-cRNA transcribed from single marker petite mtDNA's of low kinetic complexity to grande restriction fragments. We have chosen the single Sal I site as the origin of the circular physical map and have positioned the antibiotic loci as follows: C (99.5-1.Ou)--P (27-36.Ou)--OII (58.3-62u--OI (80-84u)--E (94.4-98.4u). The 21s rRNA is localized at 94.4-99.2u, and the 14s rRNA is positioned between 36.2-39.8u. The two rRNA species are separated by 36% of the genome. Total mitochondrial tRNA labeled with 125I hybridized primarily to two regions of the genome, at 99.5-11.5u and 34-44u. A third region of hybridization was occasionally detected at 70--76u, which probably corresponds to seryl and glutamyl tRNA genes, previously located to this region by petite deletion mapping.

Chloramphenicol↗
PubMed1978

Restriction enzyme analysis of mitochondrial DNAs of petite mutants of yeast: classification of petites, and deletion mapping of mitochondrial genes.

We have analyzed the restriction digest patterns of the mitochondrial DNA from 41 cytoplasmic petite strains of Saccharomyces cerevisiae, that have been extensively characterized with respect to genetic markers. Each mitochondrial DNA was digested with seven restriction endonucleases (EcoRI, HPaI, HindIII, BamHI, HhaI, SalI, and PstI) which together make 41 cuts in grande mitochondrial DNA and for which we have derived fragment maps. The petite mitochondrial DNAs were also analyzed with HpaII, HaeIII, and AluI, each of which makes more than 80 cleavages in grande mitochondrial DNA. On the basis of the restriction patterns observed (i.e., only one fragment migrating differently from grande for a single deletion, and more than one for multiple deletions) and by comparing petite and grande mitochondrial DNA restriction maps, the petite clones could be classified into two main groups: (1) petites representing a single deletion of grande mitochondrial DNA and (2) petites containing multiple deletions of the grande mitochondrial DNA resulting in rearranged sequences. Single deletion petites may retain a large portion of the grande mitochondrial genome or may be of low kinetic cimplexity. Many petites which are scored as single continuous deletions by genetic criteria were later demonstrated to be internally deleted by restriction endonuclease analysis. Heterogeneous sequences, manifested by the presence of sub-stoichiometric amounts of some restriction fragments, may accompany the single or multiple deletions. Single deletions with heterogeneous sequences remain useful for mapping if the low concentration sequences represent a subset of the stoichiometric bands. Using a group of petites which retain single continuous regions of the grande mitochondrial DNA, we have physically mapped antibiotic resistance and mit- markers to regions of the grande restriction map as follows: C (99.3--1.4 map units)--OXI-1 (2.5--15.7)--OXI-2 (18.5--25)--P (28.1--34.2)--OXI-3 (32.2--61.2--OII (60--62)--COB (64.6--80.8--0I (80.4--85.7)--E (95--98.9).

DNA Restriction Enzymes↗