A large coronal loop in the Algol system.

The close binary Algol system contains a radio-bright KIV subgiant star in a very close (0.062 astronomical units) and rapid (2.86 day) orbit with a main sequence B8 star.

Detection of the intrinsic size of Sagittarius A* through closure amplitude imaging.

We have detected the intrinsic size of Sagittarius A*, the Galactic center radio source associated with a supermassive black hole, showing that the short-wavelength radio emission arises from very near the event horizon of the black hole. Radio observations with the Very Long Baseline Array show that the source has a size of 24 +/- 2 Schwarzschild radii at 7-millimeter wavelength. In one of eight 7-millimeter epochs, we also detected an increase in the intrinsic size of 60(-17)(+25)%.

Multidrug resistance-associated protein--reduction of expression in human leukaemia cells by antisense phosphorothioate olignucleotides.

Multidrug resistance-associated protein (MRP1) causes cellular drug resistance in several cancer cell lines. In this paper we show that antisense oligonucleotides decrease MRP1 expression in human leukaemia cells. We investigated biological activity of a series of 12 linear phosphorothioate oligonucleotides, complementary to several regions of MRP1 mRNA.

A Transient Radio Source near the Center of the Milky Way Galaxy.

In late December 1990, a new radio source appeared near the center of our galaxy rivaling the intensity of Sgr A(*) (the compact radio source at the galactic center). Following its first detection, the flux density of the galactic center transient (GCT) increased rapidly to a maximum 1 month later, and then declined gradually with a time scale of about 3 months. Surprisingly, the GCT maintained a steep radio spectrum during both its rising and decay phases.

Fiber-optic rotation sensor technology.

A concept for an all-waveguide fiber-optic rotation sensor is discussed, and the results of preliminary tests of key elements are described. A single channel waveguide coupler design provides the functions of an optical switch, a 3-dB beam splitter, a phase retarder, and a signal modulator, all of which may be formed on the same chip and interconnected by channel single-mode waveguides. Preliminary test results for the waveguide coupler and for a rotation sensor without the coupler are presented.

Mutational biosynthesis by idiotrophs of Micromonospora purpurea. II. Conversion of non-amino containing cyclitols to aminoglycoside antibiotics.

A mutant of Micromonospora purpurea, which produces the gentamicin complex only when 2-deoxystreptamine is added to the fermentation medium, produces a new antibiotic complex, 2-hydroxygentamicin, when streptamine or 2,4,6/3,5-pentahydroxycyclohexanone is added to the fermentation medium. This mutant also produces the gentamicin complex when 2,4/3,5-tetrahydroxycyclohexanone is added to the fermentation medium. The C1 and C2 components of 2-hydroxygentamicin have broad spectrum in vitro antibacterial activity similar to the gentamicin C1 and C2 components, but with greater activity against some gentamicin-resistant strains.

Mutational biosynthesis by idiotrophs of Micromonospora purpurea. I. Conversion of aminocyclitols to new aminoglycoside antibiotics.

By mutation and strain improvement techniques idiotrophs of Micromonospora purpurea, the gentamicin-producing organism, were obtained which require an exogenous source of 2-deoxystreptamine in order to produce gentamicin. Streptamine incorporation afforded a mixture of 2-hydroxygentamicin C as a complex of essentially the C1 and C2 components whereas 2-deoxystreptamine when incorporated by the same idiotroph afforded the same mixture of C1, C2 and C1a gentamicins as the parent (m1) organism. The 2-hydroxygentamicin C complex exhibited broad-spectrum antibiotic activity with an in vitro potency less than that for the gentamicin C complex, but with greater activity against selected gentamicin C resistant organisms.

Application of a gloved-hand model for multiparameter measurements of skin-degerming activity.

The application of an established gloved-hand model to multiparameter measurements of skin-degerming activity is described. In particular, appropriate experimental designs are illustrated which allow characterization of performance of topical skin-cleansing preparations in terms of rapid, sustained, cummulative, and persistent skin-degerming effects on the hand. Single-contact studies were used to define the degerming activity profiles of selected commercial surgical scrub preparations, and to establish the optimal post-treatment sampling interval for individual preparations.

Evaluation of an automated colony counter.

An automated colony counter was found to readily detect surface and subsurface bacterial colonies of 0.3-mm size or greater with a high degree of precision. On a logarithmic scale, counting efficiency consistently ranged from 89 to 95% of corresponding manual count determinations for plates containing up to 1,000 colonies.

Improved experimental model for measuring skin degerming activity on the human hand.

A gloved-hand method is presented for evaluating the interaction of antimicrobial agents with the normal resident bacterial flora of human skin. One of the key features of the experimental model is a simplified technique for sampling the skin, which involves the addition of eluting fluid to the gloved hand. As with other skin sampling techniques, the number of bacteria recovered from the hands showed considerable variation from subject to subject.

The mariner spacecraft star sensors.

The development history of the star sensors used on the Mariner spacecraft is traced, and design and performance details are described. The electrooptically controlled sensor, which was developed for the 1964 Mariner IV Mars mission, was modified for the 1967 Mariner V Venus mission to withstand the intense planetary illumination. The sensor has been further modified for the 1969 Mariner mission to Mars to survive the more severe launch environment and to provide greater capability for automatic search, identification, and tracking.

Mechanism of action of nalidixic acid on Escherichia coli. Vi. Cell-free studies.

The effects of nalidixic acid in vitro on deoxyribonucleic acid (DNA)- polymerase (deoxyribonucleosidetriphosphate: DNA deoxynucleotidyltransferase, EC 2.7.7.

Induction of excessive deoxyribonucleic acid synthesis in Escherichia coli by nalidixic acid.

Prior treatment of Escherichia coli with nalidixic acid in nutritionally complete medium altered the subsequent pattern of deoxyribonucleic acid (DNA) synthesis normally observed in nutritionally deficient medium. Transfer of E. coli 15 TAU to an amino acid- and pyrimidine-deficient medium usually resulted in a 40 to 50% increase in DNA content.

Bactericidal action of nalidixic acid on Bacillus subtilis.

Cook, Thomas M. (Sterling-Winthrop Research Institute, Rensselaer, N.Y.

Mechanism of Action of Nalidixic Acid on Escherichia coli V. Possible Mutagenic Effect.

Cook, Thomas M., (Sterling-Winthrop Research Institute, Rensselaer, N.Y.

Mechanism of action of nalidixic acid on Escherichia coli. IV. Effects on the stability of cellular constituents.

Cook, Thomas M. (Sterling-Winthrop Research Institute, Rensselaer, N.Y.

Mechanism of action of nalidixic acid on Escherichia coli. 3. Conditions required for lethality.

Deitz, William H. (Sterling-Winthrop Research Institute, Rensselaer, N.Y.

MECHANISM OF ACTION OF NALIDIXIC ACID ON ESCHERICHIA COLI.II. INHIBITION OF DEOXYRIBONUCLEIC ACID SYNTHESIS.

Goss, William A. (Sterling-Winthrop Research Institute, Rensselaer, N.Y.

MECHANISM OF ACTION OF NALIDIXIC ACID ON ESCHERICHIA COLI.

Goss, William A. (Sterling-Winthrop Research Institute, Rensselaer, N.Y.