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T Lu

Publications and source records attributed to T Lu.

At least 145 records · Page 8Linked to original sources
PubMed1991

Effects of antihypertensive factor from erythrocyte of spontaneously hypertensive rats on the blood pressure and Ca2+ influx of arterial smooth muscle in rats.

The effects of a partially purified antihypertensive factor (AHF) from erythrocytes of spontaneously hypertensive rats (SHR) on the blood pressure (BP) and Ca2+ influx of vascular smooth muscle (VSM) in rats were studied. The results indicated that AHF could produce a marked prolonged depressor effect and significantly inhibit the Ca2+ influx dose-dependently on both SHR and renal hypertensive rat (RHR) either in acute or in chronic experiments, but not on normotensive rats. It suggested that the inhibition of Ca2+ influx might be one of the important mechanisms for AHF as an endogenous depressor substance.

Animals↗
PubMed1990

Surface-enhanced resonance raman scattering spectroscopy of bacterial photosynthetic membranes: orientation of the carotenoids of Rhodobacter sphaeroides 2.4.1.

Surface-enhanced resonance Raman scattering (SERRS) spectra were obtained from carotenoids, in the all-trans configuration, located on the antenna complexes of Rhodobacter sphaeroides 2.4.1 membranes. Since resonance Raman (RR) spectra are barely detectable at the concentration that SERRS signals saturate, SERRS represents a very sensitive means of detecting pigments in biological systems. Prominent SERRS spectra of sphaeroidenone were detected in chromatophores (cytoplasmic side out) but not in spheroplast-derived vesicles (periplasmic side out), demonstrating that the carotenoid is asymmetrically located on the cytoplasmic side of the cell membrane. Comparison of peak frequencies from SERRS and RR spectral data suggests that the carotenoids are oriented into the membrane with the methoxy end of the isoprenoid chains located closest to the cytoplasmic side of the intracytoplasmic membrane. This work not only shows that SERRS spectroscopy can provide information on the location of a chromophore in a biological membrane but also for the first time demonstrates that SERRS data can be used to ascertain the orientation of a chromophore within the membrane. This observation greatly increases the potential of this technique for structural analysis of intact membranes at the molecular level.

Bacterial Chromatophores↗
PubMed1990

Novel fatty acyl substrates for myristoyl-CoA:protein N-myristoyl-transferase.

Myristoyl-CoA:protein N-myristoyltransferase (NMT) catalyzes the covalent attachment of myristic acid to the NH2-terminal Gly residues of a number of viral and cellular proteins. The remarkable specificity of this enzyme for myristoyl CoA observed in vivo appears to arise in large part from a cooperativity between NMT's acylCoA and peptide binding sites: the length of the acylCoA bound to NMT influences the interactions of peptide substrates with NMT. We have previously synthesized analogs of myristic acid with single oxygen or sulfur for methylene substitutions. These heteroatom substitutions produce significant reductions in acyl chain hydrophobicity without accompanying alterations in chain length or stereochemical restrictions. In vitro studies have shown that the CoA thioesters of these analogs are substrates for S. cerevisiae NMT and that the efficiency of their transfer to octapeptide substrates is peptide sequence-dependent. In vivo studies with cultured mammalian cells have confirmed that these fatty acid analogs are selectively incorporated into a subset of cellular N-myristoylproteins, that only a subset of analog-substituted proteins undergo redistribution from membrane to cytosolic fractions, and that these analogs can inhibit the replication of human immunodeficiency virus I and Moloney murine leukemia viruses--two retroviruses that depend upon N-myristoylation of their gag polyprotein precursors for assembly. We have now extended our analysis of NMT-acylCoA interactions by synthesizing additional analogs of myristic acid and testing them in a coupled in vitro assay system. Myristic acid analogs with two oxygen or two sulfur substitutions have hydrophobicities comparable to that of hexanoic acid and decanoic acid, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acyl Coenzyme A↗
PubMed1982

Concurrence of malignant and benign heterologous mixed tumors of the uterus.

A large polypoid uterine mas was composed to two distinct and separate parts: a malignant mixed müllerian tumor (MMMT) and a benign mixed mesenchymal tumor (BMMT). It was considered a collision of two neoplasms rather than a malignant degeneration of the BMMT. Malignant transformation of benign mesenchymal uterine tumors is a controversial concept which is difficult to prove or disprove. Concerning the histogenesis of MMMT it appears, at least in some cases, that they originate not from a single multipotential mullerian cell, but rather from two, a stromal cell and an epithelial cell. It is suggested furthermore, that in certain instances presence of one neoplastic component, e.g., adenocarcinoma, can incite proliferation of the second, sarcomatous element of the MMMT.

Aged↗