Search PubMed⌕ Search

Biomedical subjects

L M Hall

Publications and source records attributed to L M Hall.

At least 127 records · Page 7Linked to original sources
PubMed1985

High-pressure liquid chromatographic methods for determining arabinosyladenine-5'-monophosphate, arabinosyladenine, and arabinosylhypoxanthine in plasma and urine.

New high-pressure liquid chromatographic methods for determining concentrations of arabinosyladenine (Ara-A), its 5'-monophosphate (Ara-AMP), and arabinosylhypoxanthine (Ara-H) in plasma and urine are presented. A fluorescence detector is used for Ara-A and Ara-AMP, which are first converted to highly fluorescent derivatives with chloroacetaldehyde. This increases sensitivity greatly over previous methods. The sensitivities of the methods (in micrograms per milliliter) are as follows: in plasma, Ara-AMP, 0.002; Ara-A, 0.0015; and Ara-H, 0.35; and in urine, 9 times these values, respectively. Drug concentration data are also presented, which were obtained after doses of Ara-AMP were given intramuscularly to two patients treated with this drug for severe herpes zoster. One patient was given 13 mg of Ara-AMP per kg of body weight once daily, and the other was given 6.5 mg/kg twice daily. Peak Ara-AMP and Ara-A levels in plasma occurred within 1 h after the doses, and neither exceeded 2 micrograms/ml. Ara-AMP and Ara-A concentrations in plasma fell to less than 0.01 micrograms/ml in both patients by 4 to 6 h after the doses. Peak Ara-H concentrations in plasma occurred within 1 to 2 h after doses and were 21 micrograms/ml in patient 1 and 2. The highest concentration of Ara-AMP in urine was 0.09 micrograms/ml. The highest Ara-A concentration in urine was 62 micrograms/ml, and the highest Ara-H concentration in urine was 1,080 micrograms/ml. An interfering substance of unknown nature, cochromatographing with Ara-H, was encountered sporadically in urine samples. An algorithm based on differential spectrophotometry to identify and correct for this problem is described. Estimates of the renal clearances of Ara-AMP, Ara-A, and Ara-H are also given.

Arabinonucleosides↗
PubMed1985

Genetic modifications of voltage-sensitive sodium channels in Drosophila: gene dosage studies of the seizure locus.

We have identified a genetic locus in Drosophila melanogaster whose product appears to have a structural role in the formation of functional voltage-sensitive sodium channels. This locus, designated seizure, is defined by two temperature-sensitive alleles (seits-1 and seits-2), each of which causes convulsive seizures followed by a rapid but reversible paralysis of adults at restrictive temperatures above 38 degrees C. Previous work had shown that seits-2 extracts display an altered pH dependence and an abnormally high Kd for [3H]-saxitoxin binding at high temperatures, suggesting that sodium channels in seits-2 mutants have an altered structure (Jackson F. R., S. D. Wilson, G. R. Strichartz, and L. M. Hall (1984) Nature 308: 189-191). These binding studies have now been extended to extracts of seits-1 which have a Kd not significantly different from wild-type at all assay temperatures. However, seits-1 extracts show a reduced number of saxitoxin binding sites (Bmax) relative to wild-type. This reduction is only 5 to 18% at 0 degree C but is 17 to 37% at 39 degrees C, suggesting that under certain conditions sodium channels in the seits-1 mutant are more labile than those of wild-type. Cytogenetic studies demonstrate that the seizure locus maps within region 60A to 60B8-10 on the second chromosome. Gene dosage analysis of approximately 99.7% of the genome, including this second chromosome region, failed to detect a wild-type locus whose dose affected saxitoxin-binding activity. Nevertheless, the mutant seits-2 allele has codominant and dose-dependent effects on paralytic behavior and saxitoxin-binding activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Drosophila cAMP-dependent protein kinase.

cAMP-dependent protein kinase has been purified to homogeneity from adult bodies of Drosophila melanogaster. It is tetrameric in structure with two regulatory and two catalytic subunits that dissociate when activated by cAMP. The regulatory subunit exists in phospho and dephospho forms, which have electrophoretic mobilities in sodium dodecyl sulfate-polyacrylamide gels corresponding to Mr = 58,000 and 52,000, respectively. The catalytic subunit has a molecular weight of 40,000. The holoenzyme has a Stokes radius of 4.7 nm. The Km for activation by cAMP is substrate-dependent with Km values of 20 nM with histone H2B and 100 nM with the peptide, Leu-Arg-Arg-Ala-Ser-Leu-Gly. These physical and kinetic properties are very similar to those of the bovine heart Type II cAMP-dependent protein kinase. A Drosophila Type I cAMP-dependent protein kinase was also found in larval stages and during the first half of pupation but was absent in embryos and adults. The fly Type II enzyme was present in all developmental stages. Three regions of the Drosophila genome were found which, when present in three copies, significantly alter the specific activity of cAMP-dependent protein kinase. These are located at 29F-33F (30% increase), 46A-50C (17% increase), and 66B-67D (16% decrease).

Animals↗
PubMed1984

Genetic activity along 315 kb of the Drosophila chromosome.

Transcripts from different tissues were mapped along a 315 kb segment of the Drosophila chromosome, a region which includes the rosy and Ace loci. Forty-three distinct RNA species were detected, though only 12 recessive lethal complementation groups had been mapped in the interval. The sum of the sizes of the transcripts covers 33% of the genomic DNA. The distribution of transcription units along the walk is very uneven. Sixty-three kb of genomic DNA at the proximal end of the walk encode 18 transcripts, while only seven are found in the next 153 kb. Each tissue exhibits a specific spectrum of transcripts. No clustering was seen among genes expressed coordinately. In salivary glands, the number of transcripts detected corresponds to the number of chromomeric units in the polytene chromosomes of this tissue. Moreover, the density distribution of transcripts along the DNA walk is parallel to the density distribution of chromomeric units.

Journal Article↗
PubMed1984

Monoclonal antibodies detect the conservation of muscarinic cholinergic receptor structure from Drosophila to human brain and detect possible structural homology with alpha 1-adrenergic receptors.

Muscarinic cholinergic receptors isolated from Drosophila heads, rat and human brain, dog heart, and monkey ciliary muscle were examined for structural similarities/differences by utilizing isoelectric focusing, sodium dodecyl sulfate/polyacrylamide gel electrophoresis, and monoclonal antibody crossreactivity. Muscarinic receptors were affinity labeled with [3H]propylbenzilylcholine mustard and subjected to isoelectric focusing. Muscarinic receptors from each species focused with an isoelectric point of 5.9. The same proteins all migrated with an apparent molecular mass of 80,000 daltons on sodium dodecyl sulfate gels. Six hybridomas secreting monoclonal antibodies specific for muscarinic receptors were developed by using purified rat brain muscarinic receptors as the antigen. The six different monoclonal antibodies immunoprecipitated muscarinic receptors from all tissues and species tested, including human and Drosophila brains, with equal efficacy. These data indicate that muscarinic receptors are highly conserved over a considerable evolutionary period. One of the six muscarinic receptor monoclonal antibodies also immunoprecipitated rat liver alpha 1-adrenergic receptors. Furthermore, two out of five monoclonal antibodies raised against alpha 1-receptors immunoprecipitated muscarinic receptors. These data suggest that some degree of structural homology exists between muscarinic cholinergic receptors and alpha 1-adrenergic receptors.

Animals↗
PubMed1984

Abnormal lactate dehydrogenase isoenzyme pattern in a critically ill patient.

We have described a patient who had an abnormal isoenzyme of lactate dehydrogenase in both serum and tissue. The presence of LD6 is indicative of a poor prognosis. Some of the biochemical characteristics of the isoenzyme are (1) LD6 is not an artifact, (2) it contains an M subunit but not an H subunit, and (3) it is not an immunoglobulin complex. We believe LD6 may arise during episodes of severe shock as lysosomes rupture and is either a previously sequestered lysosomal LD or is a lysosomal modification of LD5.

Acidosis↗
PubMed1984

Clinical significance and partial biochemical characterization of lactate dehydrogenase isoenzyme 6.

We report nine patients with a sixth band, migrating cathodic to lactate dehydrogenase 5, appearing on routine electrophoresis for serum lactate dehydrogenase (LD, EC 1.1.1.27). Eight of these patients died during their hospitalization. Acidosis, hypotension, and sepsis were the common clinical conditions preceding the band's appearance. In several cases the band appeared transiently. We examined tissue samples from two of the cases, finding LD-6 in liver and skeletal muscle but not in heart. In randomly selected autopsy tissues, LD-6 was detected consistently in liver and skeletal muscle, sometimes in spleen, kidney, and adrenal tissue, but never in heart. Biochemical studies indicate that the LD-6 isoenzyme is not an artifact or an immunoglobulin complex, is larger than the other LD isoenzymes, contains an M-subunit but not an H-subunit, has an isoelectric point in the pH range of 9.0-9.6, and is more heat stable than LD-5.

Adolescent↗
PubMed1983

Transcripts, genes and bands in 315,000 base-pairs of Drosophila DNA.

We have mapped transcripts arising from 315,000 base-pairs of DNA from chromosome region 87D,E of Drosophila melanogaster. The DNA is represented in a series of overlapping recombinant phages; it constitutes about 14 bands in the polytene chromosome from 87D5,6 to 87E5,6 and contains the essential sequences for at least 12 complementation groups. We have defined 20 discrete polyadenylated RNA species transcribed from non-repetitive DNA in the region at various developmental stages. There is a generally good correlation between the position of transcription units, chromomeric units and complementation groups but with some significant exceptions. In particular, the two large bands in the region (E1,2 and E5,6) each contain several transcription units. We also find that a major part of a large band (E1,2) has no detectable transcripts and is apparently genetically silent.

Chromosome Banding↗
PubMed1983

A new opine derived from nopaline.

Nopaline (N-[4-[(aminoiminomethyl)amino-]-1S-carboxybutyl]-2R-aminopentanedioic acid and isonopaline (N-[4-[(aminoiminomethyl)amino-1S-carboxybutyl]- 2S-aminopentanedioic acid) have been synthesized and separated by crystallization. In addition, a derivative of each of these compounds that forms spontaneously from the parent compounds under the usual crystallization conditions was isolated and characterized. The chemical properties, elemental analysis, 1H-NMR spectrum, and electrophoretic behavior of the derivative from nopaline are consistent with N-[4-[ (aminoiminomethyl)amino]-1S-carboxybutyl]-2-pyrrolidone-5R-carboxylic acid, also called pyronopaline. The presence of pyronopaline in crown gall tumor tissue and the catabolism of it by the bacterium A. tumefaciens establish it as a new opine.

Arginine↗
PubMed1983

Multiple heterogeneities in the transcribed spacers of ribosomal DNA from Xenopus laevis.

Ribosomal DNA (rDNA) from Xenopus laevis contains several heterogeneities in all three transcribed spacers, as revealed by analysis of cloned and uncloned amplified rDNA from oocytes and cloned chromosomal rDNA from erythrocytes. Heterogeneities include single base changes and length variants of one to several nucleotides. Sites of variation are widely but non-uniformly distributed, some occurring only a short distance outside the boundaries of the rRNA coding regions. No two transcription units that we have yet examined are identical throughout their transcribed spacer regions.

Animals↗
PubMed1983

alpha-Bungarotoxin labeling and acetylcholinesterase localization at the Mauthner fiber giant synapse in the hatchetfish.

Autoradiographic and histochemical techniques have been used to characterize further the pharmacology of transmission at the Mauthner fiber giant synapse of the South American hatchetfish. [125I]alpha-Bungarotoxin was applied to hatchetfish medullae and a standard autoradiographic procedure was carried out on 3- to 4-microns sections of glutaraldehyde-fixed tissue. All Mauthner fiber giant synapses, as identified by light microscopic criteria, had closely associated silver grains. Labeling was blocked by d-tubocurarine. Glutaraldehyde-fixed slices of hatchetfish medulla were stained histochemically for acetylcholinesterase; all giant synapses that could be identified in the light microscope showed heavy deposits of reaction product. Staining was blocked by diisopropyl-fluorophosphate, which inhibits both pseudocholinesterase and acetylcholinesterase, but was not blocked by tetraisopropylpyrophosphoramide, a specific pseudocholinesterase inhibitor. This evidence strongly supports the suggestion that the Mauthner fiber giant synapse is nicotinic cholinergic.

Acetylcholinesterase↗
PubMed1982

Herpes simplex virus mRNA species mapping in EcoRI fragment I.

We described the detailed characterization and high-resolution mapping of nine herpes simplex virus type 1 mRNAs encoded in EcoRI fragment I. Four of these mRNAs are partially colinear and encode the same sized polypeptide in vitro. Nucleotide sequence analysis of the DNA around the 5' ends of these mRNAs suggested that the larger may encode a small (ca. 100-dalton) polypeptide not resolvable by in vitro translation.

Base Sequence↗
PubMed1982

Decrease in creatine kinase in human prostatic carcinoma compared to benign prostatic hyperplasia.

Many previous studies have shown that a proportion of patients with carcinoma of the prostate have increased activity of the creatine kinase (E.C. 2.7.3.2) isoenzyme designated BB in sera from their peripheral blood. We have analyzed tissues from prostatic hyperplasia of 22 patients and from prostatic carcinoma of 23 additional patients. Prostatic carcinomas contain less (p less than 0.001) creatine kinase activity (units/g) than do prostates with benign prostatic hyperplasia. The facts that (a) histochemical studies that we performed confirmed the observation reported previously by others that creatine kinase activity is found primarily in the epithelial elements of hyperplastic prostates and prostatic carcinomas, (b) the carcinomas that we examined had, on the average, a somewhat larger epithelial component than the hyperplastic prostates that we examined, and (c) prostate cancer was found to contain less creatine kinase activity than hyperplastic prostates suggest that the epithelial cells in prostate cancers contain less creatine kinase activity per cell than do those from hyperplastic prostates. The BB form of creatine kinase accounts for 98% of the activity in prostatic carcinoma and in prostates without cancer. Creatine kinase has been discussed as a possible marker for prostatic carcinoma, and we had hoped that it might be useful for the assay of tumor burden. Our data suggest that, if creatine kinase is to be useful in the monitoring of tumor burden, it will be useful only in the contexts of particular patients studied longitudinally since the creatine kinase activity varies enormously among different prostatic carcinomas.

Aged↗
PubMed1980

Nucleotide sequence through the 18S-28S intergene region of a vertebrate ribosomal transcription unit.

We have determined the nucleotide sequence of part of a cloned ribosomal transcription unit from Xenopus laevis extending from the 3' region of the 18S gene through the 18S-28S intergene region into the start of the 28S gene. The 18S 3' region possess two tracts of high homology with the corresponding segments of other eukaryotic 18S genes (yeast and Bombyx mori) separated by a tract of low homology which in X. laevis is rich in G plus C. The first internal transcribed spacer, between the 18S and 5.8S genes, is 557 nucleotides long, very rich in G plus C (84%) and shows no sequence homology with the corresponding yeast sequence. The 5.8S rRNA sequence is revised slightly in the light of the DNA sequence. The second internal transcribed spacer, between the 5.8S and 28S genes, is 262 nucleotides long and is even richer in G plus C (88%) than the first internal spacer. 28S rRNA starts with the sequence pUCAG. This is encoded at the first of three closely linked TCAG sites in rDNA.

Animals↗
PubMed1980

Saxitoxin binding to sodium channels in head extracts from wild-type and tetrodotoxin-sensitive strains of Drosophila melanogaster.

Extracts prepared from heads of Drosophila melanogaster show high-affinity binding (KD = 1.9 nM) of [3H]saxitonin, a compound known to bind to and block voltage-sensitive sodium channels in other organisms. The interaction between saxitoxin and the Drosophila saxitoxin receptor is non-cooperative and reversible with a half-life of 18.3 s for binding at 4 degrees C. The saturable binding is specifically inhibited by tetrodotoxin with a K1 = 0.30 nM. The number of saturable binding sites in the extract is 97 fmol/mg protein. Since approx. 50% of the binding activity is recovered in the extract, the number of binding sites in the head is estimated to be 6.4 fmol/mg head. Nerve conduction in Drosophila larvae is completely blocked after 20 min in a bathing solution containing 200 nM tetrodotoxin. A comparison between the binding and the electrophysiological studies in Drosophila and other organisms suggests that the Drosophila saxitoxin receptor is part of the voltage-sensitive sodium channel involved in the propagation of action potentials. A mutant (ttxs), which is abnormally sensitive to dietary tetrodotoxin, is shown to be indistinguishable from wild type with respect to [3H]saxitonin-binding properties and physiological sensitivity to tetrodotoxin. These studies provide techniques which can be used to identify mutants with defects in the saxitoxin-binding component of the sodium channel.

Animals↗