Adenovirus-mediated expression of Fas ligand induces apoptosis of human prostate cancer cells

Several laboratories have reported on the apoptotic potentials of human prostate cancer (PC) cell lines in response to crosslinking of Fas (CD95/APO-1) with agonistic anti-Fas antibodies. We have re-evaluated the apoptotic potentials of seven human PC cell lines using the natural Fas ligand (FasL) in place of agonistic antibody. First, PC cell lines were tested in a standard cytotoxicity assay with a transfected cell line that stably expresses human FasL. Next, we developed an adenoviral expression system employing 293 cells that stably express crmA, a poxvirus inhibitor of apoptosis, to analyze the effects of FasL when expressed internally by the PC cell lines. Our data suggest that the apoptotic potentials of these cell lines were greatly underestimated in previous studies utilizing agonistic anti-Fas antibodies. Lastly, adenoviral-mediated expression of FasL prevented growth and induced regression of two human PC cell lines in immunodeficient mice. These preliminary in vivo results suggest a potential use for adenovirus encoding FasL as a gene therapy for PC.     

The nucleotide and deduced amino acid sequences of the encephalomyocarditis viral polyprotein coding region.

The nucleotide sequence of 7200 bases of encephalomyocarditis (EMC) viral RNA, including the complete polyprotein-coding region, was determined. The polyprotein is encoded within a unique translational reading frame, 6870 bases in length. Protein synthesis begins with the sequence Met-Ala-Thr, and ends with the sequence Leu-Phe-Trp, 126 bases from the 3' end of the RNA. Viral capsid and noncapsid proteins were aligned with the deduced amino acid sequence of the polyprotein. The proteolytic processing map follows the standard 4-3-4 picornaviral pattern except for a short leader peptide (8 kd), which precedes the capsid proteins. Identification of the proteolytic cleavage sites showed that EMC viral protease, p22, has cleavage specificity for gln-gly or gln-ser sequences with adjacent proline residues. The cleavage specificity of the host-coded protease(s) includes both tyr-pro and gln-gly sequences.     

Light control of porphyrin accumulation in acifluorfen-methyl-treated Lemna pausicostata

In Lemna pausicostata Hegelm. 6746, light is required for sufficient acifluorfenmethyl (AFM) stimulation of protoporphyrin IX (Proto IX) accumulation to cause significant herbicidal action. In darkness, AFM causes Proto IX levels to increase for about 2 h, after which Proto IX content is stable at levels significantly lower than those accumulated in light. In darkness, sucrose cannot increase levels of AFM-induced Proto IX. However, addition of δ-aminolevulinic acid (ALA) increases Proto IX levels in AFM-treated plants in darkness, demonstrating that the herbicide blocks the porphyrin pathway in darkness as it does in the light. Thus, Proto IX accumulation in darkness appears to be limited by ALA availability. This is supported by the finding that dioxoheptanoic acid caused more ALA to accumulate in light than in darkness. Heme is a feedback inhibitor of ALA synthesis, and heme synthesis is inhibited by AFM. However, total extractable heme levels were reduced by AFM by about the same amount in both light and darkness. Exogenously supplied hemin reduced AFM-caused Proto IX accumulation and herbicidal damage in the light and also reduced Proto IX accumulation caused by AFM or AFM plus ALA in darkness. AFM-stimulated Proto IX accumulation was inversely proportional to the log of the photon flux density between 5 and 500 μmol in m⁻² s⁻¹. Reduced effects of higher photon fluxes on AFM-stimulated Proto IX accumulation are probably due to both increased photobleaching of Proto IX and reduced porphyrin synthesis because of herbicidal damage. AFM-stimulated Proto IX accumulation in darkness could not be demonstrated to be under phytochrome control, but it appeared to be under the negative influence of protochlorophyllide levels.     

Analysis of thirteen populations of black cohosh for formononetin.

Black cohosh (Actaea racemosa L. syn. Cimicifuga racemosa (L.) Nutt.), a North American perennial plant, is a promising natural alternative to hormone replacement therapy for treating menopausal symptoms, but the mechanism of action is not understood. The clinical actions of this plant have been attributed to the isoflavonone formononetin since 1985, when its presence was reported in a black cohosh extract. Others have since looked for formononetin, but have not detected it. We looked for formononetin in extracts of black cohosh roots and rhizomes collected in thirteen locations in the eastern United States, including Maryland, New Jersey, New York, North Carolina, Pennsylvania, Virginia, and Tennessee. The rhizome samples were extracted using 80% methanol, and the extracts were partially purified using solid-phase extraction to concentrate any isoflavonoids that might be present. We tested for formononetin in these partially purified samples using thin-layer chromatography and high-performance liquid chromatography with a photodiode array detector and a mass spectrometer. Formononetin was not detected in any of the thirteen plant populations examined. Remifemin, a German product now on the United States market, and CimiPure, a commercially available black cohosh rhizome extract, were also analyzed. We did not detect formononetin, or ononin (formononetin-7-glucoside), in any sample tested by the above-mentioned chemical analyses. Therefore, the clinically observed estrogen-like actions of black cohosh, such as reduction of hot flashes, are likely due to a compound, or combination of compounds, other than formononetin.     

Design,synthesis, functional and structural characterization of an inhibitor of N-acetylneuraminate-9-phosphate phosphatase: Observation of extensive dynamics in an enzyme/inhibitor complex

The design, synthesis and characterization of a phosphonate inhibitor of N-acetylneuraminate-9-phosphate phosphatase (HDHD4) is described. Compound 3, where the substrate C-9 oxygen was replaced with a nonlabile CH₂ group, inhibits HDHD4 with a binding affinity (IC₅₀ 11 μM) in the range of the native substrate Neu5Ac-9-P (compound 1, K_m 47 μM). Combined SAR, modeling and NMR studies are consistent with the phosphonate group in inhibitor 3 forming a stable complex with native Mg²⁺. In addition to this key interaction, the C-1 carboxylate of the sugar interacts with a cluster of basic residues, K141, R104 and R72. Comparative NMR studies of compounds 3 and 1 with Ca²⁺ and Mg²⁺ are indicative of a highly dynamic process in the active site for the HDHD4/Mg²⁺/3 complex. Possible explanations for this observation are discussed.     

A common precursor to neurotensin and LANT6 and its differential processing in chicken tissues

Antisera towards neurotensin (NT) and the structurally related peptide, LANT6, were used to characterize immunoreactive peptides and proteins in extracts of chicken tissues. A 17 kDa protein was identified by Western blotting as a potential precursor to NT and LANT6. However, the posttranslational processing of this common precursor appeared to be tissue specific, giving rise to disproportionate amounts of NT and LANT6, along with varying expression of a large molecular LANT6 (M_r, 15 kDa). The intestinal cells containing immunoreactive NT, LANT6, and large molecular LANT6 behaved similarly during fractionation by size and density. These activities also banded together in particles resembling vesicles during centrifugation of isotonic homogenates of tissue. These results suggest that chicken NT and LANT6 are biosynthesized as parts of the same precursor, the processing of which can give rise to a variety of products stored within secretory vesicles.     

Frequency clustering in spontaneous otoacoustic emissions from a lizard's ear

Spontaneous otoacoustic emissions (SOAEs) are indicators of an active process in the inner ear that enhances the sensitivity and frequency selectivity of hearing. They are particularly regular and robust in certain lizards, so these animals are good model organisms for studying how SOAEs are generated. We show that the published properties of SOAEs in the bobtail lizard are wholly consistent with a mathematical model in which active oscillators, with exponentially varying characteristic frequencies, are coupled together in a chain by visco-elastic elements. Physically, each oscillator corresponds to a small group of hair cells, covered by a tectorial sallet, so our theoretical analysis directly links SOAEs to the micromechanics of active hair bundles.     

Defining the "fast-reacting" thiols of myosin by reaction with 1, 5 IAEDANS.

The specificity of the fluorescent reagent N-iodoacetyl-N-(5-sulfo-1-naphthyl)ethylenediamine (1,5 IAEDANS) for a specific thiol group of myosin has been characterized by a comparison with iodoacetamide (IAA) and by observing maximal enhancement of the Ca²⁺-ATPase activity and inhibition of the K⁺-EDTA-ATPase activity of myosin. The stoichiometry of the [³H]1,5 IAEDANS bound to myosin indicates the presence of two fast-reacting thiols which correspond to the “SH₁” groups responsible for the catalytic properties of myosin. Moreover, it has been unequivocally demonstrated by gel electrophoresis that the fast-reacting thiol is located on the myosin heavy chain. A single radioactivity-labeled thiol peptide obtained from tryptic digests of myosin labeled with [³H]1,5 IAEDANS or iodo[1-¹⁴C]acetamide indicates strongly that the identical thiol was labeled by both reagents.