Showing papers by "University of Texas at Dallas published in 1973"
TL;DR: Feeding breast or soy milk in place of proprietary liquid cow milk from birth to 6 months did not affect the development of childhood allergy, and the cow group showed allergy earlier than the breast group.
Abstract: Seventeen hundred and fifty-three infants fed breast, soy, or cow milk from birth to 6 months of age were followed for varying periods to 7 years to observe the development of childhood allergy. There were 45.8 per cent with an immediate family history of allergy, 15.6 per cent with a remote history, and 38.6 per cent with a negative history. Allergy occurred in 218 (12.4 per cent), 132 males, 86 females. The development of allergy was similar in the 3 milk groups. The cow group showed allergy earlier than the breast group. Diet did not affect the incidence of the allergic diseases. In 218 allergic children, gastrointestinal allergy occurred in 13 per cent, atopic dermatitis in 33 per cent, urticaria in 8.0 per cent, allergic rhinitis in 50 per cent, and asthma in 43 per cent. Feeding egg yolk before 3 weeks of age or after 6 months of age did not affect the development of allergy. Allergy to soy milk occurred in 0.5 per cent; to cow milk, in 1.8 per cent. The incidence of allergy by family history showed significant differences: immediate, 15.6 per cent; remote, 12.1 per cent; and negative, 8.8 per cent. In the immediate group, allergy occurred earlier and asthma and allergic rhinitis more often. Feeding breast or soy milk in place of proprietary liquid cow milk from birth to 6 months did not affect the development of childhood allergy.
228 citations
TL;DR: In the Magellan Basin of southern Chile, the oldest known rocks are metamorphosed as mentioned in this paper, with an initial Sr 87 Sr 86 ratio of 0.7112 ± 0.0033.
Abstract: In southern Chile the oldest known rocks are metamorphosed. Gneiss from the basement rocks of the Magellan Basin at the Atlantic entrance to the Strait of Magellan has been dated by Rb-Sr total-rock analyses at 306 ± 156 m.y. (λβ = 1.47 × 10 −11 yr −1 ), with an initial Sr 87 Sr 86 ratio of 0.7112 ± 0.0033. Biotite from a sample of gneiss has been dated as Permian age by the Rb-Sr and K-Ar methods; this implies that the basement rocks of the Magellan Basin have been involved in one or more Paleozoic geologic events. Paraschist from the basement complex along Chile9s Pacific margin indicated Paleozoic to Mesozoic total-rock Rb-Sr ages, based on an assumed initial Sr 87 Sr 86 ratio of 0.710; minerals separated from the schists gave late Mesozoic Rb-Sr and K-Ar dates. Volcanic rocks that overlie the basement rocks and are generally accepted as being of Late Jurassic or Early Cretaceous age based on stratigraphic position gave total-rock Rb-Sr and K-Ar dates of Late Cretaceous to Tertiary age; these dates are considered to represent the time of final closure of their isotopic systems, perhaps associated with deformation in the region. The plutonic igneous rocks that constitute the southern Andes Patagonian batholithic complex range in age from Jurassic to Tertiary. Late Jurassic to Early Cretaceous (155 to 120 m.y.), Late Cretaceous (100 to 75 m.y.), and middle to late Tertiary (50 to 10 m.y.) phases of magmatic activity have been recognized. In the Cordillera Darwin region of the Beagle Canal, minerals separated from plutonic rocks of the Cordillera Darwin suite and from the metamorphic rocks it intrudes gave Rb-Sr and K-Ar dates of Late Cretaceous to early Tertiary age.
137 citations
TL;DR: In this paper, the authors conclude that the intrusive rocks are best explained by repeated episodes of equilibrium fusion corresponding to magmatic sequences defined by field, petrologic, chemical, and geochronologic data.
Abstract: Chemical analyses of 167 typical specimens indicate that about 95 percent of the intrusive rocks of the central Sierra Nevada contain more than 79 percent normative Ab + An + Or + Qz. If the composition of the lower continental crust is similar to or slightly more felsic than andesite, as seems likely, the system NaAlSi 3 O 8 -CaAl 2 Si 2 O 8 -KAlSi 3 O 8 -SiO 2 -H 2 O provides an excellent chemical model for testing various schemes of fusion of the lower crust and crystallization of the resulting magmas. From consideration of this system in conjunction with field and petrographic data, we conclude that the intrusive rocks are best explained by repeated episodes of equilibrium fusion corresponding to magmatic sequences defined by field, petrologic, chemical, and geochronologic data. Fractional crystallization of the crystal-liquid mush generated by equilibrium fusion, coupled with periodic upward or lateral movement of the less crystallized central part of the magma, would produce the characteristic mafic to felsic sequence of intrusion; each mafic to felsic sequence corresponds to a separate equilibrium fusion event. In contrast, a close approach to fractional fusion of the lower crust is inadequate for obtaining most of the plutonic rocks, because rock compositions capable of being produced by this process do not match those observed. Normal amounts of conductive heat from the mantle and from radioactive decay in the crust may have been capable of causing fusion in the deepest parts of a thickened crust under the central part of the Sierra Nevada without the aid of a transient heat source from the mantle, but would have been inadequate where the crust was thin in the western Sierra Nevada. However, upward transport of andesitic and basaltic magmas generated along a Mesozoic subduction zone dipping beneath the Sierra Nevada would have provided sufficient additional heat to make fusion of the lower crust unavoidable. This implies that a major portion of the present batholith must have been derived from the lower crust.
113 citations
TL;DR: The magnetic ion-mass spectrometer as discussed by the authors is designed to measure the abundances of the ambient positive ions in the ionosphere, and it will be calibrated in flight against the retardingpotential analyzer and the cylindrical electrostatic probe to give absolute concentration data for the ion species detected.
Abstract: The magnetic ion-mass spectrometer is designed to measure the abundances of the ambient positive ions in the ionosphere. It will be calibrated in flight against the retarding-potential analyzer and the cylindrical electrostatic probe to give absolute concentration data for the ion species detected. These parameters can be measured to approximately plus or minus 10% in well-behaved regions where concentrations are above 1000/cu cm. However, in highly structured polar regions, some degradation in accuracy may be expected. Three mass ranges, covered simultaneously by the scan of the instrument, 1 to 4, 4 to 16, and 16 to 64 amu, permit measurement of the entire mass range, 1 to 64 amu, in 1 sec in the main (peaks) mode. An alternate mode, analog-long, will extend the mass range to 90 amu with a 9-sec period.
102 citations
TL;DR: A analysis of the observations revealed supercoils of first, second and third order for the above lengths, suggesting DNA supercoiling may be the consequence of dehydration by ethanol and drying and, in native chromatin, of dehydrationBy histone.
78 citations
TL;DR: Calculations indicate that the linear density of polymerase molecules on the ribosomal DNA template increases with the bacterial growth rate, such that in rapidly growing bacteria all Ribosomal RNA genes are nearly saturated with RNA polymerase.
76 citations
TL;DR: In this paper, the integrability conditions for the existence of a certain valence two Killing tensor were reduced to a simple criterion involving the ratio of the amplitude of the Weyl spinor to a test solution of the spin two zero restmass field equations.
Abstract: For Einstein-Maxwell fields for which the Weyl spinor is of type {2, 2}, and the electromagnetic field spinor is of type {1, 1} with its principal null directions coaligned with those of the Weyl spinor, the integrability conditions for the existence of a certain valence two Killing tensor are shown to reduce to a simple criterion involving the ratio of the amplitude of the Weyl spinor to the amplitude of a certain test solution of the spin two zero restmass field equations. The charged Kerr solution provides an example of a spacetime for which the criterion is satisfied; the chargedC-metric provides an example for which it is not.
68 citations
TL;DR: The relative rates of stable RNA synthesis (rate of stable synthesis/rate of total RNA synthesis) were determined for Escherichia coli Br growing in succinate, glucose and glucose/amino acids media and the relationship between these ψs values and μ has two implications for the control of RNA synthesis during a nutritional shift-up.
65 citations
TL;DR: Terbium(III) binds to nucleic acids and acts as an acceptor of electronic excitation energy and the transfer appears to be primarily from guanosine residues, potentially useful in nucleic acid studies.
61 citations
TL;DR: Evidence is given of two equivalent binding sites per monomer in the binding of Mn 2+, Ca 2+ , and rare earth ions to apoconcanavalin A by water proton relaxation enhancement, electron paramagnetic resonance spectroscopy, and fluorescence Spectroscopy.
57 citations
TL;DR: Equilibrium dialysis measurements of the binding of the allosteric activator ATP and theallosteric inhibitor CTP to native aspartate transcarbamylase show that ATP is bound at 5.1 to 6 sites with similar affinities, whereas Scatchard plots of CTP binding data display a sharp "negative" curvature indicating that CTP is bound with markedly heterogeneous affinITIES.
TL;DR: In this paper, the relative importance of several effects which influence the diurnal variation of atomic hydrogen abundance near the critical level was examined, and it was pointed out that the neglect of exospheric hydrogen in a recent theoretical treatment causes an overestimation of the durnal variation at high exosphere temperatures, and an underestimation at low exosphere temperature.
TL;DR: Polyacrylamide gel electrophoresis of unfractionated sodium dodecyl sulfate lysates of Escherichia coli B r has been used to investigate the synthesis of β and β′ subunits of RNA polymerase as a function of bacterial growth rate, suggesting an excess of total over functioningRNA polymerase.
TL;DR: CD data for 5′-UMP, and5′-CMP in 0.01 M β-cyclodextrin show that the binding is not as specific as previously reported.
TL;DR: In this paper, the photodissociation of oxygen in the lower thermosphere was evaluated to obtain its global average value and the hemispheric imbalance and the observed concentrations of atomic oxygen do not reflect this imbalance in production due to the effect of seasonal wind patterns redistributing the atomic oxygen.
TL;DR: A preliminary but comprehensive report on coordinated data obtained with the ISIS-II spacecraft, fourth in the ISIS series, launched 1 April 1971, into a near circular 1400 km orbit is given in this article.
TL;DR: There does appear to be a general decrease in the percentage usage of ribosomal and transfer RNA genes as a mammalian species' aging rate decreases, and the results are discussed with respect to a unified theory of aging for mammalian species.
TL;DR: In this paper, the simultaneous time-dependent continuity equations for O(+), H(+) and He(+) in the low latitude F-region were solved, where account is taken of E x B drift, a meridional neutral wind, and ion-ion and ion neutral drag.
TL;DR: The action of an endonuclease from Micrococcus luteus, that operates on ultraviolet (UV) radiation damage, overlaps greatly with that of the yeast photoreactivating enzyme: homo and hetero cyclobutyl pyrimidine dimers in DNA are substrate for both enzymes, but p Skyrimidine adducts or the ‘spore photoproduct’ inDNA are not.
Abstract: — The action of an endonuclease from Micrococcus luteus, that operates on ultraviolet (UV) radiation damage, overlaps greatly with that of the yeast photoreactivating enzyme: homo and hetero cyclobutyl pyrimidine dimers in DNA are substrate for both enzymes, but pyrimidine adducts or the ‘spore photoproduct’ in DNA are not.
As expected from this overlap, the action of the two enzymes is mutually interfering: single-strand nicks introduced by the endonuclease effectively preclude photoreactivation; conversely, formation of a photoreactivating enzyme-dimer complex can prevent nicking by the UV endonuclease. While complex formation between photoreactivating enzyme and dimers in UV-endonuclease-treated DNA is apparently normal, the light-dependent repair step either fails to occur or proceeds at a very low rate. Hence, besides the requirement of a minimum chain length for the function of the photoreactivating enzyme, there is the additional restriction on the position of the dimer in a polynucleotide strand.
Finally, rough approximations of the rate constants, k1 and k2, for the UV endonuclease indicate that the in vitro UV-endonuclease-dimer complex is relatively unstable, with dissociation of the complex being more probable than hydrolysis of the phosphodiester bond.
TL;DR: The analysis does infer the existence of a majority (86%) of AA, TT, AT, and TA first neighbors but does not precisely indicate their relative proportions, and the agreement between the measured and approximated spectra for poly r(AAU):r(AUU) is surprisingly good.
Abstract: We present absorption and circular dichroism (CD) spectra for the synthetic polymers poly d(AAT):d(AAT) and poly r(AAU):r(AAU), in both native and heat-denatured forms. As a means of evaluating the first-neighbor hypothesis, the CD spectra are compared with approximations derived from spectra of other synthetic polymers containing the same first-neighbor sequences. This is the first instance where such a comparison has been possible using spectra of double-stranded RNA sequences, and the agreement between the measured and approximated spectra for poly r(AAU):r(AUU) is surprisingly good. We have also subjected the CD spectrum of poly d(AAT):d(AAT) to a previously published analytical procedure for obtaining estimates of first-neighbor frequencies. In this first independent test of the procedure, we find that the analysis does infer the existence of a majority (86%) of AA, TT, AT, and TA first neighbors but does not precisely indicate their relative proportions.
TL;DR: Plasmid DNA from Escherichia coli strains harboring drug resistance either of the infectious or noninfectious kind has been separated by CsCl centrifugation of crude cell lysates in the presence of ethidium bromide and examined by electron microscopy, concluding that ampicillin resistance is carried by a DNA molecule (the A determinant) of 2.7 μm, and streptomycin-sulfonamide resistance is carrying by an independent molecule (
Abstract: Plasmid DNA from Escherichia coli strains harboring drug resistance either of the infectious or noninfectious kind has been separated by CsCl centrifugation of crude cell lysates in the presence of ethidium bromide and examined by electron microscopy. Plasmid deoxyribonucleic acid (DNA) from an S(+) strain (which has the property of noninfectious streptomycin-sulfonamide resistance) consists of a monomolecular covalently closed circular species of 2.7 mum in contour length (5.6 x 10(6) atomic mass units; amu). DNA from a strain carrying a transfer factor, termed Delta, but no determinant for drug resistance, is a monomolecular covalently closed circular species of 29.3 mum in contour length (61 x 10(6) amu). DNA from either Delta(+)A(+) or Delta(+)S(+) strains, (which are respectively ampicillin or streptomycin-sulfonamide resistant, and can transfer this drug resistance), shows a bimodal distribution of molecules of contour lengths 2.7 mum and 29.3 mum, whereas DNA from a (Delta-T)(+) strain (showing infectious tetracycline resistance) contains only one species of molecule measuring 32.3 mum (67 x 10(6) amu). We conclude that ampicillin resistance is carried by a DNA molecule (the A determinant) of 2.7 mum, and streptomycin-sulfonamide resistance is carried by an independent molecule (the S determinant) of similar size. These molecules are not able to effect their own transfer, but can be transmitted to other cells due to the simultaneous presence of the transfer factor, Delta, which also constitutes an independent molecule, of size 29.3 mum. In general, there appears to be little recombination or integration of the A or S molecules into that of Delta, although a small proportion (5-10%) of recombinant molecules cannot be excluded. In contrast, the third drug-resistance determinant, that for tetracycline resistance (denoted as T), is integrated in the Delta molecule to form the composite structure Delta-T of size 32.3 mum, which determines infectious tetracycline resistance. The Delta(+)A(+) and Delta(+)S(+) strains are defined as harboring plasmid aggregates, and the (Delta-T)(+) strain is defined as carrying a plasmid cointegrate; the properties of all three strains are characteristic of strains harboring R factors. These results are compatible with the previously published genetic data. The number of Delta molecules per cell appears to be equal to the chromosomal number irrespective of growth phase, and this plasmid can thus be defined as stringently regulated in DNA replication. In contrast, S and A exist as multiple copies, probably in at least a 10-fold excess of chromosomal copy number. S and A can thus be defined as relaxed in the regulation of their DNA replication.
TL;DR: It is shown that two distinct heterothallic - mating types exist: a stable one (h(-S)) and an unstable one ( h(-U), which can mutate to heterothallism + and homothallists.
Abstract: In the strains of Schizosaccharomyces pombe introduced by Leupold (1950, 1958) into genetic research, heterothallic and homothallic mating types are known. The mating types are determined by two closely linked genes. We show that two distinct heterothallic - mating types exist: a stable one (h(-S)) and an unstable one (h(-U)), which can mutate to heterothallism + and homothallism. A proposal for incorporation of the new mating type h(-U) into Leupold's two-gene scheme is discussed.
TL;DR: In this paper, the isobaric binary eutectic between enstatite and forsterite has been established at a composition of En 85 Fo 15 (weight percent) at 1710°C.
Abstract: Crystal-liquid equilibria have been determined in a portion of the system MgO-Al 2 O 3 -SiO 2 at 15 kb. The isobaric binary eutectic between enstatite and forsterite has been established at a composition of En 85 Fo 15 (weight percent) at 1710°C. The pressure at which enstatite changes from incongruent to congruent melting, as pressure is increased, is estimated to be approximately 4 kb. Six isobaric invariant points within the ternary system have been established which involve the phase relations between a liquid and the crystalline phases forsterite, spinel, aluminous enstatite, sapphirine, quartz, sillimanite, and corundum. Enstatite was found to contain up to 18.9 wt percent Al 2 O 3 in the assemblage quartz + sapphirine + enstatite at 1420°C. The AlAl/MgSi substitution in enstatite seems to be highly dependent upon temperature. Due to a reduction in the size of the primary phase field of forsterite with increasing pressure, partial fusion of a simplified upper-mantle material consisting of enstatite, forsterite, and spinel would produce an initial liquid richer in MgO and poorer in SiO 2 and Al 2 O 3 as pressure is increased to 15 kb. Due to a reaction relation between aluminous enstatite, forsterite, and liquid, silica-enriched liquids can be produced from silica-undersaturated compositions by fractional crystallization at high pressures. Similarly, aluminous enstatite can melt at pressures greater than approximately 4 kb, in an anhydrous environment, to produce silica-enriched liquids. The effect of alumina solid-solution and the effect of water on the melting of enstatite at high pressures are complementary effects which allow the incongruent melting of enstatite at greater depths than previously expected and support the possibility of generating silica-enriched magmas by partial fusion at high pressures as well as the production of such magmas by high-pressure fractional crystallization.
TL;DR: In this article, the two-photon ionization of molecular cesium as a continuous function of laser wavelength in the 6200-6600-AA{} region with a tunable dye laser having a 0.18-${\mathrm{Cm}}^{\ensuremath{-}1}$ linewidth was observed.
Abstract: This paper reports the observation of the two-photon ionization of molecular cesium as a continuous function of laser wavelength in the 6200-6600-\AA{} region with a tunable dye laser having a 0.18-${\mathrm{Cm}}^{\ensuremath{-}1}$ linewidth. To the author's knowledge, it serves to illustrate the first extension to neutral molecular species of the important techniques of resonant multiphoton photodetachment spectroscopy. The resulting two-photon photoionization spectrum is intepreted in terms of the vibrational structure of the resonant intermediate molecular state.
TL;DR: A rapid assay for DNA photolyase was developed that makes use of the membrane binding technique and the speed and reproducibility of the new method makes it a convenient one for assaying column effluents and as many as one hundred samples can be handled routinely in an afternoon.
Abstract: — A rapid assay for DNA photolyase was developed that makes use of the membrane binding technique of A. D. Riggs, H. Suzuki and S. Bourgeois, J. Mol. Biol.48, 67–83 (1970). The complex formed between UV-irradiated bacteriophage T7 DNA-3H and the enzyme is trapped on a nitrocellulose filter after a five-minute equilibration and is counted. Using this technique, one can calculate the molar concentration of enzyme in an enzyme preparation and the saturation constant (K) for the complex formation. The latter value is 2.6 cyclobutadipyrimidines per genome (T7) for yeast DNA photolyase; thus approximately 5.2 dipyrimidines/genome are necessary for the full retention of the DNA on the membrane. The speed and reproducibility of the new method makes it a convenient one for assaying column effluents and as many as one hundred samples can be handled routinely in an afternoon.
TL;DR: Genetic crosses between mutants defective in the known pre-early genes of T5 and BF23 and the detection of putative N-terminal fragments have allowed the determination of the order of genes along the initially transferred 8% section of DNA of these phages.
Abstract: Genetic crosses between mutants defective in the known pre-early genes of T5 and BF23 and the detection of putative N-terminal fragments have allowed the determination of the order of genes along the initially transferred 8% section of DNA of these phages.
TL;DR: Blood sampling is the easiest means of conducting a large scale investigation of lead in the human body and here some measurements are reported as part of an exploration of the feasibility of such a programme.
Abstract: THERE have been several attempts1–6 to identify the sources of lead in the air and vegetable or animal tissue by analysis of stable isotopes. Blood sampling is the easiest means of conducting a large scale investigation of lead in the human body. Here I report some measurements as part of an exploration of the feasibility of such a programme.