Stanley T. Crooke

The signal transduction system of the leukotriene D4 receptor

During the past several years, substantial progress in understanding the receptors and signal transduction processes for peptidyl leukotrienes has been reported. Receptors have been identified and characterized, the major steps in the signal transduction pathway have been described, and the genetic and epigenetic regulatory processes have been characterized. Very recent studies have defined the mechanisms by which LTE4 acts as a partial agonist at the LTD4 receptor. The cloning of the genes for the proteins involved in the major steps of the signalling process has also been initiated. Stanley Crooke and co-authors summarize this recent progress and present their current notions about the LTD4 receptor signalling process.

Genetic Engineering and Cancer Chemotherapy

Studies on the composition of newly-synthesized nucleolar and ribosomal RNA of the Novikoff rat hepatoma have demonstrated that a portion of these molecules differs from the corresponding portion of s

Comparison of bleomycin A2 and talisomycin A specific fragmentation of linear duplex DNA.

Abstract The fragmentation of Hind III digested PM2 DNA by treatment with bleomycin and talisomycin has been compared. As observed by electrophoresis on agarose gels, the ethidium bromide staining band patterns produced following incubation of the Hind III PM2 DNA with the drugs differed for bleomycin and talisomycin. These results show that in this system bleomycin and talisomycin treatment of PM2 DNA resulted in breakage of DNA producing different length DNA fragments and may indicate different site specificities for the two drugs.

Rat liver nuclear ribonucleoprotein particles: Reassociation of residues with various types of RNA

Abstract The 35–40-S nuclear ribonucleoprotein particles previously reported to be associated with messenger RNA were extracted from rat liver nuclei at pH 8 after several extractions at pH 7 released most of the more soluble ribonucleoproteins. The protein components of the ribonucleoprotein particles were analyzed by polyacrylamide gel electrophoresis; they were found in high concentrations in urea extracts of nuclei of normal liver and Morris hepatoma and in lower amounts in nuclear preparations of the Novikoff hepatoma ascites cells and a number of other nontumor tissues. The ribonucleoprotein particle was dissociated into an RNA fraction and ribonucleoprotein residue by treatment with 6 M urea or 1.1 M KCl. When the “residue fraction” was reassociated with various types of nuclear RNA, its affinity generally paralleled the amount of the specific ribonucleoprotein protein in the nuclear extracts. It had little affinity for nucleolar RNA, and had the highest affinity for nuclear 8–18-S RNA. Competition between liver nuclear RNA and nuclear RNA from other sources was determined, and in general, paralleled the presence of proteins of the ribonucleoprotein particle.

Uptake of Exogenous tRNA by Novikoff Hepatoma Ascites Cells

Summary Studies with 32P-labeled tRNA indicate that intact tRNA is efficiently taken up into Novikoff hepatoma ascites cells in the presence of DEAE-dextran (0.1 mg/ml). The 32P-tRNA was taken up intact as demonstrated by DEAE-cellulose column chromatography and sucrose density gradient centrifugation. The formation of a DEAE-dextran-tRNA complex was demonstrated by hyperchromicity, sucrose density gradient centrifugation, and the lack of precipitation of the tRNA in the complex with ethanol. Although DEAE-dextran protects tRNA from intracellular RNases, it does not protect tRNA against high concentrations of pancreatic RNase. Inhibition of uptake of tRNA by the cells with either iodoacetate (IC50 = 2 × 10-2 M) or azide (IC50 = 8 × 10-2 M) demonstrated that both cell association and uptake of tRNA are energy dependent. To demonstrate that tRNA was intracellular and not simply adsorbed, control studies were made at 0° and zero time and by treatment of the cells with pancreatic RNase after the incubations. On the basis of these studies, approximately 25% of the total tRNA in the incubation mixture was cell associated at 120 min in the presence of DEAE-D. Of the cell associated tRNA, approximately 40% was intracellular.

IN VITRO INTERACTION OF COVALENTLY LINKED CLOSED CIRCULAR DNA WITH THE SECOND-GENERATION PLATINUM COMPOUNDS

Publisher Summary The binding of cis-diamminedichloroplatinum II (CDDP or cisplatin) to cellular DNA is the major mechanism of its antitumor activity. It has been proposed that CDDP causes intra- and interstrand crosslinks in DNA molecules by coordinate bonding of cis-diamminediaquoplatinum II, the solvated form of CDDP. The strong, nearly irrevisible binding is inhibited by chloride, cyanide, or other strong electron-donating ligands. Covalently closed circular DNAs have been used to investigate the interaction of CDDP with various DNA species. Using agarose gel electrophoretic and electronmicroscopic methods, it has been reported that CDDP induced conformational changes on superhelical covalently closed circular DNAs. The second-generation platinum analogs are categorized in two classes: platinum IV compounds that appear to break PM-2 DNA in vitro and platinum II compounds that produce conformational changes in supercoiled PM-2 DNA. The breakage of CCC PM-2 DNA is related to the trans-dihydroxy groups.

MORPHOLOGICAL MANIFESTATIONS OF CISPLATIN ANALOGS IN RATS: AN ULTRASTRUCTURAL STUDY

Publisher Summary The dose-limiting nephrotoxicity of cisplatin (cis-diamminedichloroplatinum II) presents a major problem in the treatment of various malignancies with this drug. Many analogs of cisplatin have been synthesized and tested for antitumor activity in experimental animal tumors. In addition to the investigations of the activity of these analogs, various animal toxicity models have been utilized to study the nephrotoxic and myelosuppressive potential of a number of the analogs. The primary action of cisplatin is on DNA resulting in the inhibition of DNA synthesis, the cytoarchitecture of the nuclei of cells are expected to be altered after treatment with cisplatin. Giant multinucleated sarcoma 180 cells have been observed in mice after treatment with cisplatin. These nuclei are in communication with each other by thin strands of nuclear material, and there are practically no cells in mitosis. Cytoplasmic organelles such as Golgi and mitochondria also show altered morphology. The chapter discusses the ultrastructural toxicity of cisplatin analogs on organ tissues including kidney, liver, spleen, and sciatic nerve of rats.

DNA breakage activity of the methanol extract of auromomycin

SummaryThe constituents of the antitumor agent auromomycin have been analyzed to determine their DNA-breakage activities. Spectral analysis showed that the methanol extract contained 70% of the non-peptide chromophore, whereas the residue contained 20%. Amino acid analysis of the methanol extract showed that it contained 21%–26% of the original auromomycin polypeptides.The DNA-degradation activity of the extract was 121%±28% of that of the untreated auromoycin, whereas that of the residue was only 22%±3.8%. Mixing of the residue and the methanol extract resulted in the loss of three-fourths of the total activity. Agarose gel electrophoretic analysis showed that the single-strand DNA breakage activity of the methanol extract was 6.5-fold greater than that of the double-strand DNA-breakage activity.The difference in the total DNA-cleavage activity of the untreated, methanol-treated, and remixed auromomycin preparations may suggest the occurrence of certain non-peptide chromophore-polypeptide interactions in both the untreated and the remixed preparations. This is consistent with the fluorescent changes observed upon mixing of the extract and residue.Fractionation of the methanol extract by Sephadex chromatography revealed that several column fractions which were enriched with non-peptide chromophore relative to the polypeptides contained in them still had significant DNA-degradation activity. These studies suggest that the non-peptide chromophore in the auromomycin preparation may contribute to most of the observed DNA breakage activity.

Leukotriene D4 Increases the Metabolism of an Inositol Tetrakisphosphate - Containing Phospholipid in U937 Cells

Substantial progress has been made over the last several years in understanding leukotriene (LT)D4 receptors and the signal transduction process (Crooke et al., 1988; Crooke et al., 1989). LTD4 interacts with highly selective, specific receptors for LTD4 which are located on the plasma membrane and which have been characterized in guinea pig lung, guinea-pig heart, human lung, rat basophilic leukemia cells, human monocytic leukemia U937 cells, human mesangial cells and sheep tracheal smooth muscle cells. The receptors are coupled through guanine nucleotide binding proteins (G proteins) to a phosphatidylinositol-specific phospholipase C (PIP2-PLC). In U937 cells, LTD4 receptors interact with at least two types of G proteins, one being sensitive and the other insensitive to pertussis toxin. LTD4-induced activation of PIP2-PLC results in increased formation of inositol phosphates (IP), diacylglycerol (DAG) and transient increases in intracellular calcium ([ca2+]i). Subsequently, protein kinase C is activated, phosphatidyl choline specific phospholipase A2 is activated, enhancing the release of arachidonic acid and its metabolism to various products (Crooke et al., 1989).

PREFACE TO VOLUME II

This second volume to the treatise Physics of Lakes is dedicated to a single topic, namely Lakes as Oscillators. There are several reasons why this topic plays such a prominent role. First, oscillations in lakes belong to those subjects, which were already studied by the pioneers in the seventeenth century. As Mortimer writes: “Readily observed, rhythmic fluctuations in lake level have long exercised a fascination and have stimulated mathematical modeling, but often with a longtime gap between observation and theoretical resolution [20]. The first detailed set of observations ([9], on Léman, 1730, introducing the local name ‘seiche’) and recognition of their occurrences in many lakes [26] were, it is interesting to note, preceded by systematic observations and conjectures by a Jesuit missionary [3] in 1671, describing the large but irregular ‘tides’ at the head of Green Bay (a gulf which opens onto Lake Michigan) and attributing to a combination of lunar tidal influence and to the main influence of the lake. Three centuries elapsed before those conjectures were confirmed by spectral analysis and numerical modelling [12, 13, 19]”, from [20]. Mortimer continues: “With early observations and conjectures as a prelude, physical limnology was launched as a distinct branch of geophysical fluid mechanics (L’ océanographie des lacs) by Forel’s lifetime study of Léman seiches and temperature regime [10]. But again, in one respect priority must go to Lake Michigan, i.e. to a US Army surveyor’s 1872 interpretation [8] of the conspicuous 2.2 h seiche at Milwaukee as a standing wave, thereby antedating Forel’s similar interpretation [11] by 3 years and providing yet another example of an original idea occurring to two persons at about the same time. Mathematical modelling of this seiche (as the first transverse mode [23]) confirmed the 1872 interpretation. In fact, hydrodynamic modelling may be said to have ‘cut its teeth’ on seiches : : :”, from [20]. Second, since the availability of electronic computation and the development of electronically based measuring techniques, which permitted relatively long term recording of detailed time series of density (via temperature and electrical conductivity) and velocity, the internal motion of the water in lakes became ‘observable’ via the construction of isotherm-depth or isopycnal time series at fixed mooring positions. Fast Fourier and more recently wavelet transforms and cross correlation analyses of such time series between synoptically recorded quantities became key working techniques to interpret whole-basin or localized internal processes. These