PubMed Health⌕ Search

Biomedical subjects

L K Miller

Publications and source records attributed to L K Miller.

At least 181 records · Page 10Linked to original sources
PubMed1982

Molecular cloning of DNA complementary to mRNA of the baculovirus Autographa californica nuclear polyhedrosis virus: location and gene products of RNA transcripts found late in infection.

DNAs complementary to late Autographa californica nuclear polyhedrosis virus (AcNPV) mRNA were synthesized by reverse transcription and cloned in Escherichia coli by using pBR322 as a vector. Eleven different cDNAs were distinguished in our screening of 45 AcNPV-homologous clones. Location of the regions of cDNA homology with respect to the AcNPV physical map showed that the 11 cDNAs were dispersed throughout the genome. The most abundant cDNA insertion, representing approximately one-third of the late viral mRNAs, was homologous to the AcNPV HindIII-P,Q and EcoRI-P fragments. The direction of transcription in this region was from left to right on a linearized AcNPV physical map. Hybridization selection followed by in vitro translation showed that this region encoded a 7,200-dalton (7.2K) protein which comigrated with a minor protein found in the extracellular nonoccluded form of the virus (NOV). Similarly, the gene for polyhedrin, the major structural protein of the occluded virus form, was located, at least in part, in the HindIII-V/EcoRI-I region of the AcNPV map. The polyhedrin transcript represented approximately one-quarter of the viral polyadenylic acid-containing RNAs at 27 h postinfection. Another relatively abundant cDNA was homologous to the HindIII-A/EcoRI-C/SstI-G region, and RNA selected by this cDNA directed the synthesis of two proteins (31K and 30K). The protein products of five other cDNA-selected RNAs were identified. The HindIII-D/EcoRI-O, HindIII-C/EcoRI-D, HindIII-B1/EcoRI-E, and HindIII-B2/EcoRI-H regions of the AcNPV L-1 genome were homologous to RNAs which directed the synthesis of a 57K protein, a 25K protein, a 61K protein, and a 37K protein (plus a minor 26K protein), respectively. Late mRNA selected by a cDNA homologous to the HindIII-P/EcoRI-B region of the AcNPV map directed the synthesis of 31K and 30K proteins which comigrated with the 31K and 30K proteins translated from RNA selected by the HindIII-A/EcoRI-C/SstI-G cDNA. Three other cDNAs have not been correlated yet with specific protein products.

Cloning, Molecular↗
PubMed1982

Side-chain oxidation of lipoprotein-bound [24,25-3H]cholesterol in the rat: comparison of HDL and LDL and implications for bile acid synthesis.

The purpose of the study was to test the hypothesis that high density lipoprotein (HDL) cholesterol would be more easily oxidized in vivo than low density lipoprotein (LDL) cholesterol. Homologous plasma was incubated with [24,25-3H]cholesterol and fractionated by ultracentrifugation to obtain HDL and LDL each labeled with [3H] free sterol. HDL and LDL labeled with [24,25-3H]cholesteryl esters were prepared by ultracentrifugation of plasma from donor rats injected 24 hr previously with [24,25-3H]cholesterol in propylene glycol. These four labeled lipoproteins were administered to recipient rats. It was found that more tritium oxide (3H2O) was produced after the HDL doses than after the corresponding LDL doses, from 2--3-fold more when lipoprotein free cholesterol was labeled and from 2--6-fold more when lipoprotein cholesteryl esters were labeled. More 3H2O was produced from free cholesterol-labeled lipoproteins than from cholesteryl ester-labeled lipoproteins. Since oxidation of cholesterol is a measure of bile acid formation, it is concluded that under the conditions of the study HDL-cholesterol is a better precursor of bile acids than LDL-cholesterol.

Animals↗
PubMed1981

Construction of a Genetic Map of the Baculovirus Autographa californica Nuclear Polyhedrosis Virus by Marker Rescue of Temperature-Sensitive Mutants.

Mutations of seven temperature-sensitive mutants of the baculovirus Autographa californica nuclear polyhedrosis virus (NPV) were mapped with respect to the physical restriction map of the A. californica NPV DNA by marker rescue. DNAs from two distantly related NPVs of the multiply embedded type and two NPVs of the singly embedded type were unable to rescue two A. californica NPV mutants.

Journal Article↗
PubMed1981

Baculovirus induction of a DNA polymerase.

The baculovirus, Autographa california nuclear polyhedrosis virus, induced a new aphidicolin-sensitive, alpha-like, DNA polymerase upon infection of the lepidopteran noctuid, Trichoplusia ni. The new virus-induced DNA polymerase could be separated from the host alpha-like polymerase by phosphocellulose chromatography. The two polymerases differed in their sensitivities to heat inactivation, high salt concentrations, and 0.1 M phosphate buffer.

Animals↗
PubMed1981

Human breast tumor estrogen receptor: effects of molybdate and electrophoretic analyses.

The largest and smallest discrete forms of the estrogen receptor in human breast tumor cytosol were characterized by competitive steroid binding, ultracentrifugation, gel filtration, and electrophoresis in polyacrylamide gels of several concentrations. Incubation of cytosol with [3H]estradiol and centrifugation in glycerol gradients containing 20 mM Na2MoO4 and 0 or 150 mM KCl revealed a 9-10S form of the receptor. It resembles the molybdate-stabilized complexes in cytosols of other human and rodent, malignant and healthy tissues, and the complex detected in breast tumor cytosol containing leupeptin, a bacterial protease inhibitor. Preservation of receptor integrity during purification and discrimination from serum steroid-binding components are facilitated by inclusion of molybdate in all buffers. Possible mechanisms of action of molybdate include the inhibition of ribonuclease action on RNA-associated receptor forms and protection against specific proteolytic cleavage by stabilization of a phosphate group on the vulnerable residue or a neighboring one. During fractionation of tumor cytosol in the absence of molybdate, the receptor is converted to a mixture of fragments. The smallest that retains the bound steroid, the mero-receptor, resembles the products of endogenous and exogenous protease action on receptors for all classes of steroids in a wide range of tissues. The similarities between both the largest and the smallest known forms of the breast tumor estrogen receptor and corresponding forms of other receptors support the notion of the common architecture of steroid receptors in normal and malignant tissues of diverse origins.

Binding, Competitive↗
PubMed1981

Extensive abdominal lymphadenopathy in sarcoidosis.

A case of sarcoidosis with minimal pulmonary findings and extensive abdominal lymphadenopathy is presented. As radiologists continue to examine the abdomen with the newer diagnostic modalities of computed tomography and ultrasound, they may find that abdominal nodal involvement in sarcoidosis is more common than currently recognized.

Abdomen↗
PubMed1980

Virulence of cloned variants of Autographa californica nuclear polyhedrosis virus.

The relative virulence of five different genotypic variants of Autographa californica nuclear polyhedrosis virus was tested by determining the 50% lethal dose of occluded virus for larvae of Trichoplusia ni. The 50% lethal dose values of uncloned virus and the five cloned genotypic variants ranged between 10 and 21 polyhedra per larva, and no statistically significant differences were observed. Cloning has therefore neither enhanced nor decreased the virulence of this potential microbial pesticide.

Genes, Viral↗
PubMed1980

Estrogen receptor cleavage and plasminogen activation by enzymes in human breast tumor cytosol.

Estrogen receptors in cytoplasmic extracts of breast tumors from more than 40 patients were separately analyzed by gel filtration and/or ultracentrifugation under diverse conditions. Resultant patterns are presented for specimens from 11 women with infiltrating duct carcinoma and are representative of results obtained in all samples of sufficient size and receptor content (approximately 40 fmol/mg cytosol protein) for accurate determination of hydrodynamic parameters. Estradiol-binding components of intracellular origin were distinguished from the serum contaminant, sex hormone-binding globulin by their high affinity for diethylstilbestrol and negligible affinity for 5 alpha-dihydrotestosterone. The predominant molecular forms of the receptors, but not the steroid specificity, varied dramatically with experimental factors, including the duration of the fractionation procedure, ionic strength, and the presence of protease inhibitors, particularly the bacterial tripeptides N-acetyl- and N-propionyl-L-leucyl-L-leucyl-DL-arginine aldehydes (leupeptin). At least three discrete forms of the intracellular receptors were detected. The smallest labeled complex, the mero-receptor, with a sedimentation coefficient of about 3S and a Stokes radius of about 24 A, was formed during prolonged analysis of control cytosol in hypotonic or hypertonic buffers. Complexes with an intermediate sedimentation coefficient (approximately 5S) and Stokes radius (approximately 34A) were detected when control cytosol was analyzed rapidly in hypotonic buffer or when cytosol containing 50 nM leupeptin was analyzed in hypertonic buffer. The largest receptor form (10.5S, 71A) was predominant in cytosol prepared with 50 mM leupeptin and analyzed in hypotonic buffer. In this small series of patients, there was no obvious correlation between the molecular form of the receptors and the clinical status or eventual responsiveness to endocrine therapy. Preliminary studies of endogenous proteolytic enzymes in breast tumor cytosol that may be involved in mero-receptor formation included assays of plasminogen activators (EC 3.4.21.-) by fibrinolytic and spectrofluorometric techniques. The detection of high concentrations of plasminogen activators in several tumor cytosols and the inhibition of this activity by leupeptin, which stabilizes the large receptor forms in this and other systems, are consistent with a possible role of these enzymes in receptor cleavage.

Aged↗
PubMed1980

Hemispheric asymmetry: a signal detection analysis.

Subjects were asked to indicate, by a simple motor response, the presence or absence of a predesignated target letter in unilaterally presented consonant trigrams. Perceptual sensitivity (d') was signficantly greater in the right visual hemifield and did not depend upon hand of response. Reaction times were slightly higher in the left hemifield and for the left hand. Response bias (beta) did not differ between hemifields. Models of perceptual asymmetry as a consequence of information loss transcallosally are weakened by the results.

Dominance, Cerebral↗
PubMed1979

Physical Map of the DNA Genome of Autographa californica Nuclear Polyhedrosis Virus.

A physical map of the 88 x 10(6) dalton, circular DNA genome of Autographa californica nuclear polyhedrosis virus was constructed. The complete order of BamHI and XmaI restriction enzyme sites was determined. The EcoRI and HindIII fragments were partially ordered, and their general locations, relative to the BamHI and XmaI maps, were determined. Alterations in the restriction endonuclease fragment patterns of natural genotypic variants of A. californica nuclear polyhedrosis virus, including Trichoplusia ni MEV nuclear polyhedrosis virus, were located on the physical map. Alterations were found throughout the A. californica nuclear polyhedrosis virus DNA genome.

Journal Article↗
PubMed1979

Isolation, Complementation, and Initial Characterization of Temperature-Sensitive Mutants of the Baculovirus Autographa californica Nuclear Polyhedrosis Virus.

Sixteen temperature-sensitive mutants of Autographa californica nuclear polyhedrosis virus were isolated. Several interesting phenotypes were observed. A large proportion of the mutants were unable to form polyhedral occlusion bodies (polyhedra) at the nonpermissive temperature (32.5 degrees C). At 32.5 degrees C, one mutant formed plaques in which the cells lacked polyhedra. Another mutant type was defective in the production of progeny extracellular nonoccluded virus and produced a "plaque" consisting of only a single cell containing polyhedra at 32.5 degrees C. One mutant was defective in plaque formation, progeny nonoccluded virus formation, and polyhedra formation at 32.5 degrees C. Several mutants produced nonoccluded virus but failed to produce plaques or polyhedra at 32.5 degrees C. Other phenotypes were also distinguished. Complementation analyses, performed by either measuring the increase in extracellular nonoccluded virus formation or by observing polyhedra formation in mixed infections at 32.5 degrees C, indicated the presence of 15 complementation groups. A high frequency of recombination was observed. Four of the mutants were found to be host dependent in their temperature sensitivity for polyhedra formation.

Journal Article↗