Climate and geochemistry as drivers of eucalypt diversification in Australia

Eucalypts cover most of Australia. Here, we investigate the relative contribution of climate and geochemistry to the distribution and diversity of eucalypts. Using geostatistics, we estimate major element concentrations, pH, and electrical conductivity at sites where eucalypts have been recorded. We compare the median predicted geochemistry and reported substrate for individual species that appear associated with extreme conditions; this provides a partial evaluation of the predictions. We generate a site-by-species matrix by aggregating observations to the centroids of 100-km-wide grid cells, calculate diversity indices, and use numerical ecology methods (ordination, variation partitioning) to investigate the ecology of eucalypts and their response to climatic and geochemical gradients. We find that β-diversity coincides with variations in climatic and geochemical patterns. Climate and geochemistry together account for less than half of the variation in eucalypt species assemblages across Australia but for greater than 80% in areas of high species richness. Climate is more important than geochemistry in explaining eucalypts species distribution and change in assemblages across Australia as a whole but there are correlations between the two sets of environmental variables. Many individual eucalypt species and entire taxonomic sections (Aromatica, Longistylus of subgenus Eucalyptus, Dumaria, and Liberivalvae of subgenus Symphyomyrtus) have distributions affected strongly by geochemistry. We conclude that eucalypt diversity is driven by steep geochemical gradients that have arisen as climate patterns have fluctuated over Australia over the Cenozoic, generally aridifying since the Miocene. The diversification of eucalypts across Australia is thus an excellent example of co-evolution of landscapes and biota in space and time and challenges accepted notions of macroecology.

Bimetallic Ni–Cu alloy nanoparticles supported on silica for the water-gas shift reaction: activating surface hydroxyls via enhanced CO adsorption

Strong CO adsorption activates surface OH for enhanced WGS activity.

Shapes of a suspended curly hair

We investigate how natural curvature affects the configuration of a thin elastic rod suspended under its own weight, as when a single strand of hair hangs under gravity. We combine precision desktop experiments, numerics, and theoretical analysis to explore the equilibrium shapes set by the coupled effects of elasticity, natural curvature, nonlinear geometry, and gravity. A phase diagram is constructed in terms of the control parameters of the system, namely the dimensionless curvature and weight, where we identify three distinct regions: planar curls, localized helices, and global helices. We analyze the stability of planar configurations, and describe the localization of helical patterns for long rods, near their free end. The observed shapes and their associated phase boundaries are then rationalized based on the underlying physical ingredients.

The role of discriminative stimuli in concurrent performances

Key pecking in pigeons was examined under concurrent and parallel arrangements of two independent and simultaneously available variable-interval schedules. Pecks on the changeover key alternated the schedule of reinforcement for responses on the main key. Under concurrent schedules, discriminative stimuli were paired with the reinforcement schedule arranged in each component and changeover responses also alternated these stimuli. Under parallel schedules, changeover responses alternated the effective reinforcement schedule, but did not change the discriminative stimulus. On concurrent procedures, changeover response rate was inversely related to the difference in reinforcement rate between the two components, whereas on parallel schedules no consistent relationship was found. With both schedules, absolute response and reinforcement rates were positively related, although for a given set of reinforcement frequencies, rates were often higher on the concurrent schedules. On concurrent schedules, relative response rates and relative times were equal to relative reinforcement rates. On parallel schedules these ratios were positively related, but response and time ratios were much smaller than were obtained with comparable concurrent schedules. This inequality was most pronounced when absolute reinforcement frequencies were lowest.

An efficient homologous recombination vector pTV(I) contains a hot spot for increased recombinant protein expression in Chinese hamster ovary cells

We employed reverse genetics to clone a 5.0 kb genomic DNA hot spot HIRPE (hot spot for increased recombinant protein expression) flanking the plasmid integration site from a recombinant Chinese hamster ovary (CHO) cell line. DNA sequence analysis of the 5.0 kb fragment revealed that HIRPE is enriched for repetitive elements, Alu-like sequences and matrix-associated regions that are known to be linked with transcriptionally active regions in a number of mammalian systems. The construction of a homologous recombination vector, pTV1, containing the 5.0 kb HIRPE genomic DNA, a recombinant gene human CTLA4-Ig, and the dhfr gene as a positive selection marker is described. It was observed that the pTV1 vector targeted the CTLA4Ig gene to a preferred locus in the CHO genome contributing to high recombinant gene expression in transfected CHO cells. Preliminary studies suggest that similar to the observation with the parental cell line, pTV1-generated transfectomas that were analyzed appear to harbor an inverted duplication of the genomic DNA at the plasmid integration site.

A novel interaction of tRNA(Lys,3) with the feline immunodeficiency virus RNA genome governs initiation of minus strand DNA synthesis

Complementarity between nucleotides at the 5' terminus of tRNA(Lys,3) and the U5-IR loop of the feline immunodeficiency virus RNA genome suggests a novel intermolecular interaction controls initiation of minus strand synthesis in a manner analogous to other retroviral systems. Base pairing of this tRNA-viral RNA duplex was confirmed by nuclease mapping of the RNA genome containing full-length or 5'-deleted variants of tRNA(Lys,3) hybridized to the primer-binding site. A major pause in RNA-dependent DNA synthesis occurred 14 nucleotides ahead of the primer-binding site with natural and synthetic tRNA(Lys,3) primers, indicating it was not a consequence of tRNA base modifications. The majority of the paused complexes resulted in dissociation of the reverse transcriptase from the template/primer, as demonstrated by an assay limited to a single binding event. Hybridization of a tRNA mutant whose 5' nucleotides are deleted relieved pausing at this position and subsequently allowed high level DNA synthesis. Additional experiments with tRNA-DNA chimeric primers were used to localize the stage of minus strand synthesis at which the tRNA-viral RNA interaction was disrupted. Finally, replacing nucleotides of the feline immunodeficiency virus U5-IR loop with the (A)(4) sequence of its human immunodeficiency virus (HIV)-1 counterpart also relieved pausing, but did not induce pausing immediately downstream of the primer-binding site previously noted during initiation of HIV-1 DNA synthesis. These combined observations provide further evidence of cis-acting sequences immediately adjacent to the primer-binding site controlling initiation of minus strand DNA synthesis in retroviruses and retrotransposons.

Molecular phylogenetics of Acacia (Fabaceae: Mimosoideae) based on the chloroplast MATK coding sequence and flanking TRNK intron spacer regions

The tribe Acacieae (Fabaceae: Mimosoideae) contains two genera, the monotypic African Faidherbia and the pantropical Acacia, which comprise about 1200 species with over 950 confined to Australia. As currently recognized, the genus Acacia is subdivided into three subgenera: subg. Acacia, subg. Aculeiferum, and the predominantly Australian subg. Phyllodineae. Morphological studies have suggested the tribe Acacieae and genus Acacia are artificial and have a close affinity to the tribe Ingeae. Based on available data there is no consensus on whether Acacia should be subdivided. Sequence analysis of the chloroplast trnK intron, including the matK coding region and flanking noncoding regions, indicate that neither the tribe Acacieae nor the genus Acacia are monophyletic. Two subgenera are monophyletic; section Filicinae of subgenus Aculeiferum does not group with taxa of the subgenus. Section Filicinae, eight Ingeae genera, and Faidherbia form a weakly supported paraphyletic grade with respect to subg. Phyllodineae. Acacia subg. Aculeiferum (s. s.) is sister to the grade. These data suggest that characters currently used to differentiate taxa at the tribal, generic, and subgeneric levels are polymorphic and homoplasious in cladistic analyses.

Molecular phylogenetics of Acacia (Fabaceae: Mimosoideae) based on the chloroplast MATK coding sequence and flanking TRNK intron spacer regions

The tribe Acacieae (Fabaceae: Mimosoideae) contains two genera, the monotypic African Faidherbia and the pantropical Acacia, which comprise about 1200 species with over 950 confined to Australia. As currently recognized, the genus Acacia is subdivided into three subgenera: subg. Acacia, subg. Aculeiferum, and the predominantly Australian subg. Phyllodineae. Morphological studies have suggested the tribe Acacieae and genus Acacia are artificial and have a close affinity to the tribe Ingeae. Based on available data there is no consensus on whether Acacia should be subdivided. Sequence analysis of the chloroplast trnK intron, including the matK coding region and flanking noncoding regions, indicate that neither the tribe Acacieae nor the genus Acacia are monophyletic. Two subgenera are monophyletic; section Filicinae of subgenus Aculeiferum does not group with taxa of the subgenus. Section Filicinae, eight Ingeae genera, and Faidherbia form a weakly supported paraphyletic grade with respect to subg. Phyllodineae. Acacia subg. Aculeiferum (s. s.) is sister to the grade. These data suggest that characters currently used to differentiate taxa at the tribal, generic, and subgeneric levels are polymorphic and homoplasious in cladistic analyses.

[Phosphinic analog of methionine inhibits growth of leucosis cell L1210 and transforms to phosphinic analog of S-adenosylmethionine]

A phosphinic analogue of methionine bearing a phosphinic H(OH)(O)P fragment in place of the carboxyl group inhibited the growth of the L1210 cells and was intracellularly transformed to the phosphinic analogue of S-adenosylmethionine.

Interaction of p55 reverse transcriptase from the Saccharomyces cerevisiae retrotransposon Ty3 with conformationally distinct nucleic acid duplexes

The 55-kDa reverse transcriptase (RT) domain of the Ty3 POL3 open reading frame was purified and evaluated on conformationally distinct nucleic acid duplexes. Purified enzyme migrated as a monomer by size exclusion chromatography. Enzymatic footprinting indicate Ty3 RT protects template nucleotides +7 through -21 and primer nucleotides -1 through -24. Contrary to previous data with retroviral enzymes, a 4-base pair region of the template-primer duplex remained nuclease accessible. The C-terminal portion of Ty3 RT encodes a functional RNase H domain, although the hydrolysis profile suggests an increased spatial separation between the catalytic centers. Despite conservation of catalytically important residues in the RNase H domain, Fe(2+) fails to replace Mg(2+) in the RNase H catalytic center for localized generation of hydroxyl radicals, again suggesting this domain may be structurally distinct from its retroviral counterparts. RNase H specificity was investigated using a model system challenging the enzyme to select the polypurine tract primer from within an RNA/DNA hybrid, extend this into (+) DNA, and excise the primer from nascent DNA. Purified RT catalyzed each of these three steps but was almost inactive on a non-polypurine tract RNA primer. Our studies provide the first detailed characterization of the enzymatic activities of a retrotransposon reverse transcriptase.

Polyamine analogue induction of the p53-p21WAF1/CIP1-Rb pathway and G1 arrest in human melanoma cells

Although polyamines are well recognized for their critical involvement in cell growth, the cell cycle specificity of this requirement has not yet been characterized with respect to the newly delineated regulatory pathways. We recently reported that polyamine analogues having close structural and functional similarities to the natural polyamines produce a distinct G1 and G2-M cell cycle arrest in MALME-3M human melanoma cells. To determine a molecular basis for this observation, we examined the effects of N1,N11-diethylnorspermine on cell cycle regulatory proteins associated with G1 arrest. The analogue is known to deplete polyamine pools by suppressing biosynthetic enzymes and potently inducing the polyamine catabolic enzyme spermidine/spermine N1-acetyltransferase. Treatment of MALME-3M cells with 10 microM N1,N11-diethylnorspermine caused an increase in hypophosphorylated Rb, which correlated temporally with the onset of G1 arrest at 16-24 h. Rb hypophosphorylation was preceded by an increase in wild-type p53 (approximately 100-fold at maximum) and a concomitant increase in the cyclin-dependent kinase inhibitor, p21WAF1/CIP1 (p21; approximately 5-fold at maximum). Another cyclin-dependent kinase inhibitor, p27KIP1, and cyclin D increased slightly, whereas proliferating cell nuclear antigen and p130 remained unchanged. Induction of p21 protein was accompanied by an increase in p21 mRNA, whereas induction of p53 protein was not, suggesting transcriptional activation of the former and posttranscriptional regulation of the latter. SK-MEL-28 human melanoma cells, which contain a mutated p53, failed to induce p53 or p21 and did not arrest in G1. Rather, these cells rapidly underwent programmed cell death within 48 h. Overall, these findings provide the first indication of the cell cycle regulatory pathways by which polyamine antagonists such as analogues might inhibit growth in cells containing wild-type p53 and further suggest a mechanistic basis for differential cellular responses to these agents.

Retrotransposon-related DNA sequences in the centromeres of grass chromosomes

Several distinct DNA fragments were subcloned from a sorghum (Sorghum bicolor) bacterial artificial chromosome clone 13I16 that was derived from a centromere. Three fragments showed significant sequence identity to either Ty3/gypsy- or Ty1/copia-like retrotransposons. Fluorescence in situ hybridization (FISH) analysis revealed that the Ty1/copia-related DNA sequences are not specific to the centromeric regions. However, the Ty3/gypsy-related sequences were present exclusively in the centromeres of all sorghum chromosomes. FISH and gel-blot hybridization showed that these sequences are also conserved in the centromeric regions of all species within Gramineae. Thus, we report a new retrotransposon that is conserved in specific chromosomal regions of distantly related eukaryotic species. We propose that the Ty3/gypsy-like retrotransposons in the grass centromeres may be ancient insertions and are likely to have been amplified during centromere evolution. The possible role of centromeric retrotransposons in plant centromere function is discussed.

Rice (Oryza sativa) centromeric regions consist of complex DNA

Rice bacterial artificial chromosome clones containing centromeric DNA were isolated by using a DNA sequence (pSau3A9) that is present in the centromeres of Gramineae species. Seven distinct repetitive DNA elements were isolated from a 75-kilobase rice bacterial artificial chromosome clone. All seven DNA elements are present in every rice centromere as demonstrated by fluorescence in situ hybridization. Six of the elements are middle repetitive, and their copy numbers range from approximately 50 to approximately 300 in the rice genome. Five of these six middle repetitive DNA elements are present in all of the Gramineae species, and the other element is detected only in species within the Bambusoideae subfamily of Gramineae. All six middle repetitive DNA elements are dispersed in the centromeric regions. The seventh element, the RCS2 family, is a tandem repeat of a 168-bp sequence that is represented approximately 6,000 times in the rice genome and is detected only in Oryza species. Fiber-fluorescence in situ hybridization analysis revealed that the RCS2 family is organized into long uninterrupted arrays and resembles previously reported tandem repeats located in the centromeres of human and Arabidopsis thaliana chromosomes. We characterized a large DNA fragment derived from a plant centromere and demonstrated that rice centromeres consist of complex DNA, including both highly and middle repetitive DNA sequences.

Mutating a region of HIV-1 reverse transcriptase implicated in tRNA(Lys-3) binding and the consequences for (-)-strand DNA synthesis

Recently, tRNALys-3 was cross-linked via its anticodon loop to human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) between residues 230 and 357 (Mishima, Y., and Steitz, J. A. (1995) EMBO J. 14, 2679-2687). Scanning the surface of this region identified three basic amino acids Lys249, Arg307, and Lys311 flanking a small crevice on the p66 thumb subdomain outside the primer-template binding cleft. To assess an interaction of this region with the tRNA anticodon loop, these p66 residues were altered to Glu or Gln. p66 subunits containing K249Q, K311Q, K311E, and a dual R307E/K311E mutation formed a stable dimer with wild type p51. All mutants showed reduced affinity for tRNALys-3 and supported significantly less (-)-strand DNA synthesis from this primer than the parental heterodimer. In contrast, these variants efficiently synthesized HIV-1 (-)-strand strong-stop DNA from oligonucleotide primers and had minimal effect on RNase H activity, retaining endonucleolytic and directed cleavage of an RNA/DNA hybrid. Structural features of binary RT.tRNALys-3 complexes were examined by in situ footprinting, via susceptibility to 1, 10-phenanthroline-copper-mediated cleavage. Unlike wild type RT, mutants p66(K311Q)/p51 and p66(K311E)/p51 failed to protect the tRNA anticodon domain from chemical cleavage, indicating a significant structural alteration in the binary RT.tRNA complex. These results suggest a crevice in the p66 thumb subdomain of HIV-1 RT supports an interaction with the tRNALys-3 anticodon loop critical for efficient (-)-strand DNA synthesis.

Human prostatic carcinoma cell lines display altered regulation of polyamine transport in response to polyamine analogs and inhibitors

BACKGROUND

The possibility was investigated that complex homeostatic mechanisms which maintain polyamine pools in prostate-derived tumors may differ from those which are typically seen in other tissues and tumors.

METHODS

Growth sensitivity and various regulatory responses were investigated in three human prostate carcinoma cell lines (LNCaP, DU145, and PC-3) treated with the inhibitor of S-adenosylmethionine decarboxylase CGP-48664 or the polyamine analog N1,N11-diethylnorspermine (DENSPM), both of which are currently undergoing phase I clinical trial.

RESULTS

Prostate tumor cell lines were all similarly growth-inhibited by the inhibitor CGP-48664 (IC50 values, 1-5 microM at 72 hr), but varied considerably in their sensitivity to DENSPM. The rank-order for cell-line growth inhibition by the analog was DU145 > PC-3 > LNCaP, with IC50 values of 1, 30, and 1,000 microM, respectively. Both compounds depleted intracellular polyamine pools to levels which seemed sufficient to account for inhibition of cell growth. While polyamine enzyme regulatory responses to both CGP-48664 and DENSPM were typical of those seen in other cell types, regulation of polyamine transport differed distinctly. Based on Vmax determinations, LNCaP cells failed to upregulate transport in response to CGP-48664, while PC-3 and LNCaP cells failed to downregulate transport in response to DENSPM.

CONCLUSIONS

Relative to other cell lines, polyamine transport in prostate carcinoma cell lines was found to be uniquely insensitive to regulation by polyamines or analogs. Although this did not seem to correlate with growth sensitivity to polyamine analogs in vitro, it should be therapeutically exploitable in in vivo systems.

Multiple biological roles associated with the Rous sarcoma virus 5' untranslated RNA U5-IR stem and loop

The 5' untranslated region of Rous sarcoma virus (RSV) RNA is a highly ordered structure involved in multiple processes in the viral replication cycle. One of these structures, referred to as the U5-IR stem, is located immediately upstream of the 5' end of the primer binding site. Disruption of its base pairing results in a decrease in initiation of reverse transcription (D. Cobrinik, A. Aiyar, Z. Ge, M. Katzman, H. Huang, and J. Leis, J. Virol. 65:3864-3872, 1991). In the present study, the length of the U5-IR stem structure has been extended by insertions of different sequences which decrease the efficiency of reverse transcription, in vivo and in vitro. Reverse transcription is rescued partially by placing single-stranded bulges into the middle of the extended duplexes. Nucleotide substitutions or insertions into the loop region of the U5-IR stem also decrease the efficiency of reverse transcription, suggesting that these sequences may specifically interact with reverse transcriptase. Surprisingly, all of the extended stem mutations cause significant RNA packaging defects. In contrast, nucleotide insertions or base substitutions in the U5-IR loop do not affect RNA packaging. These data indicate that the reverse transcription initiation complex and RNA packaging apparatus are influenced by the same region of RSV RNA and that each process is differentially sensitive to changes in sequence and/or secondary structure.

Cholecystojejunostomy varices demonstrated by enteroclysis

Varices in unusual sites constitute a minor but significant cause of gastrointestinal bleeding in patients with liver disease. We report a case of varices across the anastomotic line between the jejunum and gallbladder after cholecystojejunostomy. Although such varices have been demonstrated by angiography, to our knowledge they have never been demonstrated by small bowel enema (enteroclysis). We report a case and describe the findings on enteroclysis.

Comparison of four molecular markers in measuring relationships among the wild potato relatives Solanum section Etuberosum (subgenus Potatoe)

We evaluated chloroplast DNA (cpDNA), isozymes, single to low-copy nuclear DNA (RFLPs), and random amplified polymorphic DNAs (RAPDs) in terms of concordance for genetic distance of 15 accessions each of Solanum etuberosum and S. palustre, and 4 accessions of S. fernandezianum. These self-compatible, diploid (2n=24), and morphologically very similar taxa constitute all species in Solanum sect. Etuberosum, a group of non-tuber-bearing species closely related to Solanum sect. Petota (the potato and its wild relatives). Genetic distance and multidimentional scaling results show general concordance of isozymes, RFLPs and RAPDs between all three taxa; cpDNA shows S. etuberosum and S. palustre to be more similar to each other than to S. fernandezianum. Interspecific sampling variance shows a gradation of resolution from allozyme (low) to RAPD to RFLP (high); while intraspecific comparisons graded from RFLPs (low) to RAPDs (high; lack of sufficient allozyme variability within species precluded comparisons for allozymes). Experimental error was low in RFLPs and RAPDs.

Characterization of tyrosine phosphorylation of paxillin in vitro by focal adhesion kinase

The concomitant tyrosine phosphorylation of the focal adhesion protein, paxillin, and the tyrosine kinase, focal adhesion kinase (FAK), in response to multiple stimuli including integrin-mediated cell adhesion suggests that paxillin phosphorylation is closely coupled to FAK activity. In the present study, we have identified a specific tyrosine residue within paxillin, tyrosine 118 (Tyr-118), that represents the principle site of phosphorylation by FAK in vitro. The identification of this site as a target for FAK phosphorylation was accomplished by immunoprecipitating FAK and performing in vitro kinase assays, using as substrate either glutathione S-transferase (GST)-paxillin fusion proteins containing truncations in paxillin sequence or fusion proteins with phenylalanine substitutions for tyrosine residues. GST-paxillin containing a phenylalanine substitution at Tyr-118 (Y118F) was not phosphorylated by FAK immunoprecipitates; however, this mutant was shown to bind FAK equally as well as the wild type fusion protein. As a first step toward assessing the function of paxillin phosphorylation on Tyr-118, a Y118F paxillin cDNA construct was transiently transfected into NIH 3T3 cells. Similar to wild type paxillin, mutated paxillin localized to focal adhesions, indicating that the phosphorylation of paxillin on Tyr-118 is not essential for the recruitment of paxillin to sites of cell adhesion.

Femoral artery catheterization complications: a study of 503 consecutive patients

This report describes a prospective randomized trial of 503 patients who underwent a cardiac catheterization or interventional procedure at a single institution. In an effort to study femoral complications postprocedure, we evaluated three methods of femoral artery hemostasis as well as 38 variables that were felt to potentially relate to local complications. Only a marginally significant relationship between the hemostasis method and complication rate was found. The factors that contributed to femoral artery complications were: restarting heparin postsheath removal, number of procedures done during one hospitalization, noncompliance of the patient with bedrest after the procedure, number of arterial punctures to initiate the procedure, and preprocedure treatment with corticosteroids.

Primary sequence of paxillin contains putative SH2 and SH3 domain binding motifs and multiple LIM domains: identification of a vinculin and pp125Fak-binding region

Paxillin is a cytoskeletal protein involved in actin-membrane attachment at sites of cell adhesion to the extracellular matrix. Extensive tyrosine phosphorylation of this protein occurs during integrin-mediated cell adhesion, embryonic development, fibroblast transformation and following stimulation of cells by mitogens that operate through the family of seven membrane-spanning G-protein-coupled receptors. Paxillin binds in vitro to the focal adhesion protein vinculin as well as to the SH3 domain of c-src and, when tyrosine phosphorylated, to the SH2 domain of v-crk. Here, we report the complementary DNA, and derived amino acid sequence, that codes for approximately 90% of the paxillin protein. We have identified a region in the amino-terminal half of the protein that supports the binding of both vinculin and the focal adhesion tyrosine kinase, pp125Fak. Although there is no significant overall homology with other identified proteins, the carboxyl third of paxillin contains one LIM domain and three LIM-like sequences. The LIM motif is common to a number of transcription factors and to two other focal adhesion proteins, zyxin and cysteine-rich protein. In addition to several potential tyrosine phosphorylation sites there are five tyrosine-containing sequences that conform to SH2-binding motifs. The protein also contains a short proline-rich region indicative of a SH3-binding domain. Taken together, these data suggest that paxillin is a unique cytoskeletal protein capable of interaction with a variety of intracellular signalling, and structural, molecules important in growth control and the regulation of cytoskeletal organization.(ABSTRACT TRUNCATED AT 250 WORDS)

Staphylococcal esophagitis causing giant ulcers

A 29-year-old woman with Hodgkin disease developed odynophagia while receiving chemotherapy. Large esophageal ulcers due to staphylococcal infection of the mucosa were visualized by endoscopy and radiography. This unusual bacterial esophagitis represents another potential cause of giant esophageal ulcerations.

Regulation of polyamine transport by polyamines and polyamine analogs

Regulation of polyamine transport in murine L1210 leukemia cells was characterized in order to better understand its relationship to specific intracellular polyamines and their analogs and to quantitate the sensitivity by which it is controlled. Up-regulation of polyamine uptake was evaluated following a 48-hr treatment with a combination of biosynthetic enzyme inhibitors to deplete intracellular polyamine pools. The latter declined gradually over 48 hr and was accompanied by a steady increase in spermidine (SPD) and spermine (SPM) transport as indicated by rises in Vmax to levels approximately 4.5 times higher than control values. Restoration of individual polyamine pools during a 6-hr period following inhibitor treatment revealed that SPD and SPM uptake could not be selectively affected by specific pool changes. The effectiveness of individual polyamines in reversing inhibitor-induced stimulation of uptake was as follows: putrescine < SPD < SPM = the SPM analog, N1, N12-bis(ethyl)spermine (BESPM). In contrast to stimulation of transport, down-regulation by exogenous polyamines or analogs occurred rapidly and in response to subtle increases in intracellular pools. Following a 1-hr exposure to 10 microM BESPM, Vmax values for SPD and SPM fell by 70%, whereas the analog pool increased to only 400-500 pmol/10(6) cells--about 15-20% of the total polyamine pool (approximately 2.8 nmol/10(6) cells). SPM produced nearly identical regulatory effects on transport kinetics. Both BESPM and SPM were even more effective at down-regulating transport that had been previously stimulated four to fivefold by polyamine depletion achieved with enzyme inhibitors. A dose response with BESPM at 48 hr revealed a biphasic effect on uptake whereby concentrations of analog < 3 microM produced an increase in SPD and SPM Vmax values, whereas concentrations 3 microM and higher produced a marked suppression of these values. Cells treated with 3 microM BESPM for 2 hr and placed in analog-free medium recovered transport capability in only 3 hr. Thus, whereas stimulation of polyamine transport is a relatively insensitive and slowly responsive process that tends to parallel polyamine depletion, down-regulation of polyamine transport by exogenous polyamines and analogs and its reversal are rapidly responsive events that correlate with relatively small (i.e., 15-20%) changes in intracellular polyamine pools.

Differential effects of the spermine analog, N1, N12-bis(ethyl)-spermine, on polyamine metabolism and cell growth in human melanoma cell lines and melanocytes

We have previously found that in one of two human melanoma cell lines, potent increase in the polyamine catabolizing enzyme, spermidine/spermine N1-acetyltransferase (SSAT), correlate with growth sensitivity to the spermine analog, N1, N12-bis(ethyl) spermine (BESPM). Herein, we examine the generality of this SSAT response among seven human melanoma cell lines (LOX, SH-1, STO-1, HO, PANUT-3, MALME-3 and Ebey) and normal melanocytes and further evaluate its possible correlation with growth sensitivity. Following treatment with 10 microM BESPM for 48 hr, SSAT activity among the various cell lines increased from basal levels of 20-90 pmol/min/mg to levels ranging from 170 to 30,470 pmol/min/mg. Five of the seven cell lines and melanocytes induced SSAT activity to levels to greater than 2,500 pmol/min/mg and three of these, to levels greater than 10,000 pmol/min/mg. When ranked according to SSAT responsiveness (LOX less than SH-1 less than STO-1 less than HO less than PANUT-3 less than MALME3 less than Ebey), there was a general correlation among the cell lines with growth sensitivity. Antiproliferative effects ranged from slowing of cell growth in the less SSAT responsive lines (LOX, SH-1) to total cessation of cell growth or overt cytotoxicity in the more potently SSAT responsive lines (MALME-3, Ebey). The polyamine biosynthetic enzyme activities, ornithine and S-adenosylmethionine decarboxylase, were similarly suppressed in all cell lines, presumably via analog activation of inherent regulatory mechanisms. Polyamine pool reduction occurred to a greater extent than predicted in cell lines where SSAT was increased to greater than 2500 pmol/min/mg suggesting a possible role for the enzyme in enhancing polyamine excretion and/or catabolism. The occurrence of potent SSAT induction among several human melanoma cell lines and the growth sensitivity of these same lines to BESPM suggests that the enzyme response may represent a determinant of drug action in this particular malignancy.

Two distant upstream regions containing cis-acting signals regulating splicing facilitate 3'-end processing of avian sarcoma virus RNA

Retroviruses, pararetroviruses, and related retrotransposons generate terminally redundant RNAs by transcription of a template flanked by long terminal repeats in which initiation occurs within the 5' long terminal repeat sequences and 3'-end processing occurs within the 3' long terminal repeat sequences. Processing of avian sarcoma virus RNA is relatively inefficient; approximately 15% of the viral RNA transcripts are read-through products; i.e., they are not processed at the viral poly(A) addition site but at sites in the cellular sequence further downstream. In this report, we show that the efficiency of processing at the viral site is further reduced by deletion of two distant upstream sequences: (i) a 606-nucleotide sequence in the gag gene containing a cis-acting negative regulator of splicing and (ii) a 136-nucleotide sequence spanning the env 3' splice site. The deletion of either or both upstream regions increases the levels of read-through products of both unspliced and spliced viral RNA. In contrast, deletion of the src 3' splice site does not affect the efficiency of processing at the viral poly(A) addition site. The effects on 3'-end processing are not correlated either with distance from the promoter to the poly(A) addition site or with the overall level of viral RNA splicing. Substitution of the avian sarcoma virus poly(A) signal with the simian virus 40 early or late poly(A) signal relieves the requirement for the distant upstream sequences. We propose that cellular factors, which may correspond to splicing factors, bound to the upstream viral sequences may interact with factors bound at the avian sarcoma virus poly(A) signal to stabilize the polyadenylation-cleavage complex and allow for more efficient 3'-end processing.

Current therapy of impending myocardial infarction and acute cholecystitis

The authors discuss the treatment of severe coronary artery disease and acute cholecystitis using laparoscopic laser in one instance and percutaneous transluminal coronary angioplasty (PTCA) in the other. Their report demonstrates that both can be applied with relative safety in close temporal proximity.

Targeting 5'-deoxy-5'-(methylthio)adenosine phosphorylase by 5'-haloalkyl analogues of 5'-deoxy-5'-(methylthio)adenosine

A series of 5'-haloalkyl-modified analogues of 5'-deoxy-5'-(methylthio)adenosine (MTA), a nucleoside byproduct of polyamine biosynthesis, has been synthesized: 5'-deoxy-5'-[(2-monofluoroethyl)thio]adenosine (10), 5'-deoxy-5'-[(2-chloroethyl)thio]adenosine (4), 5'-deoxy-5'-[(2-bromoethyl)thio] adenosine (5), and 5'-deoxy-5'-[(3-monofluoropropyl)thio]adenosine (13). On the basis of their abilities to serve as substrates of MTA phosphorylase prepared from mouse liver, several of these analogues were characterized for their growth inhibitory effects in MTA phosphorylase-containing (murine L5178Y and human MOLT-4) and MTA phosphorylase-deficient (murine L1210 and human CCRF-CEM) leukemia cell lines. The MTA phosphorylase-containing tumor cell lines, especially of human origin, were found to be more sensitive to treatment by these analogues. Of the analogue series, 10 was the most potent inhibitor of growth in each of the cell lines tested. The analogues, especially compound 10, displayed a reduced capacity to alter polyamine pools relative to MTA, mechanistically indicating a decreased potential for interactions at sites other than MTA phosphorylase. The results indicate that of the analogues tested, compound 10 displayed the best inhibitor/substrate interaction with MTA phosphorylase, which, in turn, correlated with more potent growth inhibition in tumor cell lines containing MTA phosphorylase. Overall, this supports the concept that MTA phosphorylase plays a role in the activation of such analogues.

Foreign body retrieval using a simple snare device

We report three patients who had intravascular catheter fragments removed using an easily made snare device fashioned from a 0.038 inch movable-core J-wire and a multi-purpose catheter. The device is easily manipulated and facilitates safe removal of embolized catheters.

Use of exchange wires in coronary angioplasty

A 300 cm exchange guide wire was used as the primary wire in 59 consecutive patients referred for percutaneous transluminal coronary angioplasty. The success rate of the angioplasty using this as the only wire was 92% (54 of 59), and we were able to pass the exchange guide wire into the distal vessel in 56 of the 59 patients (95%). We believe the exchange wire technique has a place in the first-line approach to complex coronary angioplasty.

Effects of beta-adrenergic blockade on nitroglycerin-induced augmentation of regional coronary blood flow in patients

Although beta-adrenergic blockade may increase coronary vascular resistance in some patients with severe ischemic heart disease, the effects of beta blockade on the nitroglycerin (NTG)-induced augmentation of coronary blood flow have not been elucidated. Therefore, systemic hemodynamic and anterior left ventricular regional coronary blood-flow (thermodilution) data were measured during administration of NTG into the left coronary artery, before and 10 min after intravenous propranolol (0.1 mg/kg) in 22 patients. Six patients (Group 1) had normal left coronary arteries and nine (Group 2) had severe coronary artery disease with at least greater than 70% narrowing of the left anterior descending artery. In seven additional patients (three without and four with greater than 70% left anterior descending coronary artery disease), measurements were obtained with constant-paced heart rates (Group 3). Before beta blockade, NTG (200 mcg) significantly increased anterior regional great-vein flow [for Group 1, 84 +/- 38% (81 +/- 20 to 140 +/- 60 ml/min); Group 2, 39 +/- 41% (61 +/- 26 to 83 +/- 38 ml/min); and Group 3, 87 +/- 55% (75 +/- 36 to 144 +/- 86 ml/min)]. In Groups 1 and 2, beta-adrenergic blockade reduced heart rate 10% (p less than 0.01) but did not affect mean arterial or pulmonary artery pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitroglycerin-induced coronary vasodilatory responses in patients during isometric handgrip exercise

Intracoronary nitroglycerin is frequently administered during invasive procedures such as coronary angioplasty or thrombolysis which may be associated with pain and sympathetic neural stimulation. Whether sympathetic-mediated reflex vasoconstriction interferes with nitroglycerin-induced augmentation of coronary blood flow is unknown. Therefore, coronary and systemic hemodynamics were measured in 19 patients during isometric handgrip exercise (3 min x 25% maximal effort), during intracoronary nitroglycerin, and during handgrip plus intracoronary nitroglycerin. Nine patients had no significant left anterior descending coronary artery stenosis (group 1) and ten patients had greater than 70% left anterior descending coronary artery stenosis (group 2). Handgrip exercise increased heart rate, mean arterial pressure, and coronary sinus and great vein flow 15% while increasing coronary resistance 10%. Intracoronary nitroglycerin (200 micrograms) reduced mean arterial pressure -4 +/- 6% and increased great cardiac vein flow 35-72%. Anterior left ventricular regional coronary flow responses to intracoronary nitroglycerin were unaffected by sympathetic stimulation for group 1. Group 2 had a greater increase in great vein flow with intracoronary nitroglycerin plus handgrip compared to nitroglycerin alone due to increased mean arterial pressure with no change in the great vein resistance. These data indicate that sympathetic stimulation does not alter the nitroglycerin-induced augmentation of coronary sinus and great vein blood flow in patients with and without significant left anterior descending coronary artery stenosis. In patients undergoing invasive interventions who may have increased circulating catecholamines, mild sympathetic (isometric) stimulation does not appear to interfere with the coronary vasodilatory responses to intracoronary nitroglycerin.

Attenuation of nitroglycerin-induced coronary hyperemic blood flow in patients with left anterior descending coronary collaterals

Although intracoronary nitroglycerin (NTG) is frequently administered to patients having occluded coronary arteries undergoing invasive procedures such as percutaneous transluminal coronary angioplasty or thrombolysis, the extent of NTG-induced augmentation of myocardial blood flow in patients with collaterally filled occluded arteries is incompletely understood. To examine NTG-induced increases in coronary blood flow in patients with occluded left anterior descending coronary arteries (LAD), coronary and systemic hemodynamics were measured during bolus administration of NTG into the left coronary artery in 10 patients with normal LAD (Group 1), 11 patients with greater than 70% and less than 100% narrowing of the LAD (Group 2), and 10 patients who had total occlusion of the LAD with angiographic collateral filling and anterior ventricular wall motion abnormalities (Group 3). NTG increased anterior regional great vein flow (thermodilution) from 72 +/- 19 to 140 +/- 60 ml/min (p less than 0.05), 67 +/- 27 to 108 +/- 66 ml/min (p less than 0.05), and 59 +/- 27 to 74 +/- 36 ml/min (p = NS vs. control, p less than 0.05 vs. peak flow for Group 1) with relative increases from control of 91 +/- 41%, 56 +/- 34%, and 25 +/- 22% for the three groups, respectively. The percent change for Group 3 was significantly lower than both Groups 1 (p less than 0.01) and 2 (p less than 0.05). These data indicate that myocardial hyperemic blood flow responses to intracoronary NTG are markedly attenuated in patients with occluded but collaterally supplied vessels. During invasive procedures in these patients, although significantly attenuated, intracoronary NTG may potentially provide a beneficial effect by augmenting blood flow through collaterals or in adjacent regions.

Dose-related effects of intracoronary nitroglycerin on coronary hyperemia in patients with coronary artery disease

Although intracoronary nitroglycerin (NTG) is frequently required during percutaneous transluminal coronary angioplasty or thrombolysis, the dose-related hemodynamic effects and the extent to which intracoronary NTG--induced coronary hyperemia is limited in patients with coronary artery disease have not been defined. Therefore, we studied 19 patients with coronary artery disease (nine with no or minimal luminal narrowing of the left anterior descending coronary artery [group 1] and 10 with significant left anterior descending coronary stenosis [group 2]; mean arterial pressure and thermodilution coronary sinus and great cardiac vein blood flow were measured during bolus administrations of 50, 200, and 300 micrograms of intracoronary NTG. During the NTG-induced hyperemia, mean arterial pressure decreased 0%, 4% (both p = NS), and 6% (p less than 0.05) after 50, 200, and 300 micrograms doses, respectively. heart rate did not change. Global coronary hyperemia was greatest for 200 micrograms with coronary blood flow increasing (74 +/- 32% in group 1 and 53 +/- 25% for group 2) but was significantly different from 50 micrograms only in group 2 patients. Moreover, the regional coronary blood flow responses were attenuated in group 2 compared to group 1 for 50 micrograms, 18 +/- 13% vs 38 +/- 18%, and for 200 micrograms, 35 +/- 15% vs 72 +/- 34% (both p less than 0.05), with the reduction of regional coronary resistance in group 2 attenuated for all three doses of intracoronary NTG. The 300 micrograms dose did not provide further augmentation of either global or regional coronary blood flow or greater reduction in coronary resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Morse-code-controlled computer aid for the nonvocal quadriplegic

A computer-based communications system was established for a quadriplegic patient who suffered a brainstem infarction that left him with normal intelligence, but without speech and without functional motor control except for the thumb of his right hand. An arm brace was developed to support the hand and thumb so it could control two switches that generated Morse code signals. An interface was also devised to translate Morse code into ASCII characters to access a personal computer. Additional codes were added to represent keyboard control functions. This device allows the patient to communicate with others and control, to some extent, his environment.