Selective modification of fluciclovine (18F) transport in prostate carcinoma xenografts.

We investigated if previously demonstrated inhibition of fluciclovine (18F) in vitro could be replicated in a PC3-Luc xenograft mouse model. Following intratumoral injection of 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH), alpha-(methylamino)isobutyric acid (MeAIB) or saline, fluciclovine PET tumor-to-background activity was 43.6 (± 5.4)% and 25.3 (± 5.2)% lower in BCH (n = 6) and MeAIB (n = 5) injected PC3 Luc xenografts, respectively, compared to saline-injected controls (n = 2). Partial inhibition of fluciclovine uptake by BCH and MeAIB can be demonstrated in vivo similar to previous in vitro modeling.

Dwarf8 polymorphisms associate with variation in flowering time.

Historically, association tests have been used extensively in medical genetics, but have had virtually no application in plant genetics. One obstacle to their application is the structured populations often found in crop plants, which may lead to nonfunctional, spurious associations. In this study, statistical methods to account for population structure were extended for use with quantitative variation and applied to our evaluation of maize flowering time. Mutagenesis and quantitative trait locus (QTL) studies suggested that the maize gene Dwarf8 might affect the quantitative variation of maize flowering time and plant height. The wheat orthologs of this gene contributed to the increased yields seen in the 'Green Revolution' varieties. We used association approaches to evaluate Dwarf8 sequence polymorphisms from 92 maize inbred lines. Population structure was estimated using a Bayesian analysis of 141 simple sequence repeat (SSR) loci. Our results indicate that a suite of polymorphisms associate with differences in flowering time, which include a deletion that may alter a key domain in the coding region. The distribution of nonsynonymous polymorphisms suggests that Dwarf8 has been a target of selection.

Regional myocardial substrate uptake in hypertensive rats: a quantitative autoradiographic measurement.

Severe hypertension causes global and regional changes in myocardial perfusion and substrate utilization. Regional perfusion and fatty acid utilization were evaluated by dual-tracer autoradiography in normotensive and hypertensive rats of the Dahl strain. The regional distributions of perfusion and fatty acid utilization were homogeneous in normotensive rats. Severe hypertension was associated with a homogeneous pattern of regional perfusion, but fatty acid utilization was focally decreased in the free wall of the left ventricle. The decrease in fatty acid uptake was associated with a concomitant increase in glucose utilization. These findings suggest that severe hypertension is associated with uniform myocardial perfusion and focal alterations in the substrates used for the performance of myocardial work.

Feasibility of Hyperfunctioning Parathyroid Gland Localization Using [18F]fluciclovine PET/CT.

PURPOSE: To evaluate the ability of anti-1-amino-3-anti-1-amino-3-[18F]fluorocyclobutane-1-carboxylic acid ([18F]fluciclovine) positron emission tomography/X-ray computed tomography (PET/CT) in comparison to Technetium-99m 2-methoxy isobutyl isonitrile ([99mTc]sestamibi) single-photon emission computed tomography/CT (SPECT/CT) for the localization of hyperfunctioning parathyroid glands in patients with hyperparathyroidism. PROCEDURES: Four patients with hyperparathyroidism underwent 60-minutes sequential neck and thorax PET/CT after [18F]fluciclovine (352 ± 28 MBq) injection. Lesion uptake and target-to-background ratios (TBR) were compared with [99mTc]sestamibi (798 ± 27 MBq) SPECT/CT in the same patient. RESULTS: Both techniques detected 4/5 hyperfunctioning parathyroid glands identified at surgery. The highest [18F]fluciclovine uptake and TBRs were at 5-9 min with rapid washout. [99mTc]sestamibi had significantly higher TBRs compared with [18F]fluciclovine (5-9 min) for blood pool (10.9 ± 4.7 vs 1.3 ± 0.6; p < 0.01) and reference muscle backgrounds (5.8 ± 3.0 vs 1.7 ± 0.6; p < 0.01), with non-significant trend for thyroid tissue background (1.3 ± 0.5 vs 1.1 ± 0.5; p = 0.73). CONCLUSION: Hyperfunctioning parathyroid glands can be detected on [18F]fluciclovine PET/CT at early imaging, but conspicuity (TBR) is better with [99mTc]sestamibi. [18F]fluciclovine PET/CT does not seem promising in the detection of hyperfunctioning parathyroid glands.

Identification of quantitative trait Loci for resistance to southern leaf blight and days to anthesis in a maize recombinant inbred line population.

ABSTRACT A recombinant inbred line population derived from a cross between the maize lines NC300 (resistant) and B104 (susceptible) was evaluated for resistance to southern leaf blight (SLB) disease caused by Cochliobolus heterostrophus race O and for days to anthesis in four environments (Clayton, NC, and Tifton, GA, in both 2004 and 2005). Entry mean and average genetic correlations between disease ratings in different environments were high (0.78 to 0.89 and 0.9, respectively) and the overall entry mean heritability for SLB resistance was 0.89. When weighted mean disease ratings were fitted to a model using multiple interval mapping, seven potential quantitative trait loci (QTL) were identified, the two strongest being on chromosomes 3 (bin 3.04) and 9 (bin 9.03-9.04). These QTL explained a combined 80% of the phenotypic variation for SLB resistance. Some time-point-specific SLB resistance QTL were also identified. There was no significant correlation between disease resistance and days to anthesis. Six putative QTL for time to anthesis were identified, none of which coincided with any SLB resistance QTL.

Accumulation of radioiodinated 15-(p-iodophenyl)-6-tellurapentadecanoic acid in ischemic myocardium during acute coronary occlusion and reperfusion.

The myocardial uptake of 15-(p-iodophenyl)-6- tellurapentadecanoic acid ( TPDA ) was studied in dogs during coronary occlusion and after reperfusion. In eight dogs with a 3 hour occlusion (Group A) with (n = 5) and without (n = 3) 30 minutes of reperfusion, iodine-125 TPDA uptake correlated well with microsphere myocardial blood flow over a wide range of flow levels (n = 111, r = 0.94). In six dogs with a 20 minute occlusion of the left anterior descending coronary artery and 1 hour of reperfusion (Group B), iodine-125 TPDA uptake correlated equally well with myocardial blood flow (n = 37, r = 0.90). There was no difference between the slopes of regression lines for Groups A and B, indicating no release from the myocardium of radioiodinated TPDA . Dual radiolabeling of TPDA was employed in five Group A animals by intravenous injection of iodine-125 TPDA during coronary occlusion and iodine-131 TPDA after reperfusion. In 63 myocardial samples, microsphere reperfusion flow and iodine-131 TPDA uptake were closely correlated (r = 0.91). As with monovalent cations, at myocardial flows higher than control flows, iodine-131 TPDA uptake was flow-limited. It is concluded that: 1) radioiodinated TPDA accurately reveals severely ischemic areas of myocardium without myocardial release of the radionuclide in coronary occlusions lasting 20 to 180 minutes and followed by reperfusion, and 2) double radiolabeled TPDA allows assessment of both occlusion and reperfusion flows. This compound may find an application in the measurement of infarct size and the evaluation of interventional therapies in acute myocardial infarction.

Comparative recombination distances among Zea mays L. inbreds, wide crosses and interspecific hybrids.

Recombination distances and linkage heterogeneity were compared among a wide range of maize inbreds, wide crosses and maize x teosinte hybrids. Twelve maize and four teosinte races were backcrossed to stocks fixed for rare marker alleles on chromosome arm 1L. Recombination fraction estimates were higher for exotic germplasm than for either U.S. maize or maize x teosinte crosses. Serrano, Tuxpeño and a US-adapted inbred line of tropical origin, NC300, exhibited enhanced recombination. Three of the four maize x teosinte hybrids had little or no recombination between two loci. The observed recombination "shrinkage" resulted from an apparent inversion in the vicinity of the Amp1 locus. Average recombination distances among common marker loci for composite maps were highly variable, even when map construction was restricted to maize germplasm of similar origins.

Linkage relationships of 19 enzyme Loci in maize.

Linkage relationships of 19 enzyme loci have been examined. The chromosomal locations of eight of these loci are formally reported for the first time in this paper. These localizations should assist in the construction of additional useful chromosome marker stocks, especially since several of these enzyme loci lie in regions that were previously poorly mapped. Six loci are on the long arm of chromosome 1. The arrangement is (centromere)-Mdh4-mmm-Pgm1-Adh1-Phi-Gdh1, with about 46% recombination between Mdh4 and Gdh1.-Linkage studies with a2 and pr have resulted in the localization of four enzyme genes to chromosome 5 with arrangement Pgm2-Mdh5-Got3-a2-(centromere)-pr-Got2. Pgm2 lies approximately 35 map units distal to a2 in a previously unmapped region of the short arm of 5, beyond ameiotic.-Approximately 23% recombination was observed between Mdh4 and Pgm1 on chromosome 1, while 17% recombination occurred between Mdh5 and Pgm2 on chromosome 5. Similarly, linkages between Idh1 and Mdh1, about 22 map units apart on chromosome 8, and between Mdh2 and Idh2, less than 5 map units apart on chromosome 6, were observed. Thus, segments of chromosomes 1 and 5 and segments of 6 and 8 may represent duplications on nonhomologous chromosomes.

Patterns of mitochondrial DNA variation in indigenous maize races of latin america.

Mitochondrial DNAs (mtDNAs) were isolated from 93 diverse races of maize from Latin America. DNAs were examined by agarose gel electrophoresis of undigested DNA and by BamHI and EcoRI cleavage fragment analysis. Eighteen races contained plasmid-like mtDNAs. One race contained the S-1 and S-2 molecules associated with the S cytoplasmic male-sterile, and 17 were found to have the R-1 and R-2 plasmid-like DNAs. BamHI digestion of mtDNAs generated ten distinct electrophoretograms, and Eco RI digestion produced eight different fragment patterns. Races were assigned to one of 18 groups according to EcoRI and BamHI fragment patterns and whether or not they contained plasmid-like DNAs. Eight races produced restriction patterns similar to one of the characterized cytoplasmic male-steriles C, T, or S. Races from Meso-America and some from South America with Meso-American affinities were separated from other South American races. South American races were placed in three general classes of related groups. There was considerable agreement among the groupings here and those based on morphological and cytological affinities.

Use of genetic effects and genotype by environmental interactions for the classification of mexican races of maize.

To examine the questions of whether the additive and dominance effects present for morphological characters in racial crosses are of sufficient consistency and magnitude to allow such genetic effects to be used for racial classification, we used a diallel experiment among the 25 well-defined Mexican races of maize, which include the ancestral stocks of most commercial and genetic maize types. With such an experiment, genetic effects and genotype by environmental interactions for one or more characters can be used to measure genetic and adaptational or environmental similarity. We used average parental effects (general combining abilities), specific effects, and genotype by environmental effects of 21 characters from the diallel (grown at three locations) to group the Mexican races of maize. The groupings based upon average genetic effects and upon genotype by environmental interactions are more satisfactory than groupings based upon specific effects. The standard errors for genetic distances based upon specific (largely dominance) effects seem to be too high for practical use. Principal components analyses of the same data suggest a similar conclusion.-The groupings based upon average genetic effects are in general agreement with previous studies, with the exception of Maíz Dulce, which is grouped with the Cónicos, rather than being isolated from the other Mexican races of maize.

Genetic control of malate dehydrogenase isozymes in maize.

At least six nuclear loci are responsible for the genetic control of malate dehydrogenase (L-malate: NAD oxidoreductase; EC 1.1.1.37; MDH) in coleoptiles of maize. Three independently segregating loci (Mdh1, Mdh2, Mdh3) govern the production of MDH isozymes resistant to inactivation by ascorbic acid and found largely or solely in the mitochondria. A rare recessive allele found at a fourth nuclear locus (mmm) causes increased electrophoretic mobility of the MDH isozymes governed by the Mdh1, Mdh2 and Mdh3 loci.-Two loci (Mdh4, Mdh5) govern MDH isozymes that are selectively inactivated by homogenization in an ascorbic acid solution and that appear to be nonmitochondrial (soluble). Mdh4 and Mdh5 segregate independently of each other and independently of Mdh1, Mdh2 and Mdh3. However, there is close linkage between the migration modifier and Mdh4.--Multiple alleles have been found for all of the Mdh loci except the migration modifier, and electrophoretically "null" or near "null" alleles (as expressed in standardized sections of maize coleoptile) have been found for all loci except Mdh4. Duplicate inheritance commonly occurs for Mdh1 and Mdh2 and also for Mdh4 and Mdh5.--Inter- and intragenic heterodimers are formed between sub-units specified by the three loci governing the mitochondrial MDH isozymes. The same is true of the alleles and nonalleles at the two loci governing the soluble variants. No such heterodimers are formed by interactions between mitochondrial and soluble MDH isozymes.

Allozyme Frequency Changes Associated with Selection for Increased Grain Yield in Maize (ZEA MAYS L.).

Frequency changes of alleles at eight enzyme loci were monitored in four long-term maize selection experiments. The results indicate that changes in frequencies of the alleles at these loci are associated with changes due to selection for improved grain yield. The frequencies changed more than is consistent with the hypothesis of selective neutrality. In addition, significant deviations from a random-drift model were nearly always accompanied by significant linear trends as would result if allozyme frequencies respond to directional selection. Evaluations of linkages and linkage disequilibria in the selected populations indicate that the eight enzyme loci responded independently as selection progressed.

A candidate recombination modifier gene for Zea mays L.

Maize meiotic mutant desynaptic (dy) was tested as a candidate recombination modifier gene because its effect is manifested in prophase I. Recombination rates for desynaptic (dy) and its wild type were compared in two ways: (1) segregation analysis using six linked molecular markers on chromosome 1L and (2) cytogenetic analysis using fluorescence in situ hybridization (FISH)-aided meiotic configurations observed in metaphase I. Chromosome 1L map lengths among the six linked markers were 45-63 cM for five F2 dy/dy plants, significantly lower than the wild-type F2 map distance of 72 cM. Chromosomes 2 and 6 were marked with rDNA FISH probes, and their map lengths were estimated from FISH-adorned meiotic configurations using the expectation-maximization algorithm. Chiasma frequencies for dy/dy plants were significantly reduced for both arms of chromosome 2, for chromosome arm 6L, and for eight unidentified chromosomes. There was a notable exception for the nucleolus-organizing region-bearing arm chromosome arm 6S, where dy increased chiasma frequency. Maize meiotic mutant desynaptic is a recombination modifier gene based on cytogenetic and segregation analyses.

Evolution of anthocyanin biosynthesis in maize kernels: the role of regulatory and enzymatic loci.

Understanding which genes contribute to evolutionary change and the nature of the alterations in them are fundamental challenges in evolution. We analyzed regulatory and enzymatic genes in the maize anthocyanin pathway as related to the evolution of anthocyanin-pigmented kernels in maize from colorless kernels of its progenitor, teosinte. Genetic tests indicate that teosinte possesses functional alleles at all enzymatic loci. At two regulatory loci, most teosintes possess alleles that encode functional proteins, but ones that are not expressed during kernel development and not capable of activating anthocyanin biosynthesis there. We investigated nucleotide polymorphism at one of the regulatory loci, cl. Several observations suggest that cl has not evolved in a strictly neutral manner, including an exceptionally low level of polymorphism and a biased representation of haplotypes in maize. Curiously, sequence data show that most of our teosinte samples possess a promoter element necessary for the activation of the anthocyanin pathway during kernel development, although genetic tests indicate that teosinte cl alleles are not active during kernel development. Our analyses suggest that the evolution of the purple kernels resulted from changes in cis regulatory elements at regulatory loci and not changes in either regulatory protein function nor the enzymatic loci.

A model of human melanoma in cyclosporine-immunosuppressed rats.

A human malignant melanoma maintained in athymic nude mice has been successfully implanted and grown in cyclosporine (Cys)-immunosuppressed Lewis rats. Suspended melanoma cells (10(6)) or solid tumor sections measuring 2-4 mm in diameter were implanted s.c. in rats receiving parenteral Cys doses of 15-50 mg/kg each day for 1 week, and 3 times per week thereafter. Eighty-five percent of solid tumor sections implanted in animals receiving 25 mg/kg resulted in tumor growth, whereas no tumors grew from cell suspension injection sites. The average maximum tumor growth rate was 2 cm3/day, with a doubling time of 8 days. Tumors retained pretransplant gross and microscopic morphology, karyotype, and labeling index. Possible advantages of this model over the athymic nude mouse include greater longevity, larger animal and tumor size, and less stringent aseptic environmental requirements. This model may prove useful for further study of the pathophysiology of melanoma and for testing of new antimelanoma therapies.

Butanol is superior to water for performing positron emission tomography activation studies.

[15(O)]Butanol has been shown to be superior to [15(O)]water for measuring cerebral blood flow with positron emission tomography. This work demonstrates that it is also superior for performing activation studies. Data were collected under three conditions: a visual confrontation animal-naming task, nonsense figure size discrimination, and a nonvisual darkroom control task. Time-activity curves (TAC) were obtained for regions known to be activated by the confrontation naming task to compare absolute uptake and the different kinetics of the two tracers. Also, t statistic maps were calculated from the data of 10 subjects for both tracers and compared for magnitude of change and size of activated regions. Peak uptake in the whole-brain TAC were similar for the two tracers. For all regions and conditions, the washout rate of [15(O)]butanol was 41% greater than that of [15(O)]water. At a threshold of 0, the [15(O)]water and [15(O)]butanol percent difference (nonnormalized) and t statistic (global normalization) images are nearly identical, indicating that the same property is being measured with both tracers. The [15(O)]butanol parametric images displayed at a threshold of /t/ = 5 look similar to the [15(O)]water parametric maps displayed at a threshold of /t/ = 4, which is consistent with the observation that t statistic values in [15(O)]butanol images are generally greater. The t statistic values were equal when the [15(O)]butanol parametric map was created from any subset of 6 subjects and the [15(O)]water parametric map was created from all 10 subjects. Fewer subjects need to be studied with [15(O)]butanol to reach the same statistical power as an [15(O)]water-based study.

Digoxin-quinidine-spironolactone interaction.

Digoxin kinetics are substantially altered by quinidine and by spironolactone. We evaluated the effect of the combination of quinidine and spironolactone on digoxin kinetics and compared it to the effect on digoxin of each drug alone. Six normal subjects each received a 1.0-mg intravenous dose of digoxin alone, digoxin with quinidine, digoxin with spironolactone, and digoxin with both quinidine and spironolactone. Spironolactone and quinidine, alone and in combination, reduced digoxin systemic, renal, and nonrenal clearances and prolonged digoxin elimination t 1/2. A greater alteration in digoxin kinetics was induced by quinidine than by spironolactone, and an even greater effect resulted from the combination. We did not assess clinical consequences of the interaction. We advise reduction in digoxin dose, careful clinical evaluation, and measurement of serum digoxin concentrations when digoxin is used in combination with quinidine and spironolactone.

Synthesis and evaluation of radioiodinated terminal p-iodophenyl-substituted alpha- and beta-methyl-branched fatty acids.

Methods have been developed for the preparation of terminal p-idophenyl-substituted alpha- and beta-methyl-branched long-chain fatty acids. The syntheses and physical properties of 14-(p-iodophenyl)-2(RS)-methyltetradecanoic acid and 15-p-iodophenyl)-3(RS)-methylpentadecanoic acid are described. The radioiodinated agents are of interest as a result of the expected pronounced uptake and prolonged myocardial retention that may result from the inhibition of fatty acid metabolism. Tissue distribution studies in rats with 14-(p-[125I]iodophenyl)-2(RS)-methyltetradecanoic acid and 15-(p-[125I]iodophenyl)-3(RS)-methylpentadecanoic acid show significant heart uptake and prolonged retention accompanied by low in vivo deiodination and high blood levels. A comparison of the heart uptake of the radioiodinated methyl-branched fatty acids and their unbranched analogues has demonstrated a greater myocardial retention of the methyl-branched fatty acids than the unbranched analogues. These results suggest that the mechanism of myocardial retention results from steric or chemical inhibition of the metabolism of these fatty acids by the presence of the methyl group.

Design, synthesis, and evaluation of omega-iodovinyl- and omega-iodoalkyl-substituted methyl-branched long-chain fatty acids.

The synthesis of a new methyl-branched fatty acid, (E)-19-iodo-3(RS)-methyl-18-nonadecenoic acid (19), is described. Methyl branching has been introduced at the 3-position to inhibit beta-oxidation and radioiodide has been attached as a trans-vinyl iodide. Preparation of 19 involved a 15-step sequence of reactions climaxing with formation of the methyl ester 18 by iododestannylation of methyl (E)-19-(tri-n-butylstannyl)-3(RS)-methyl-18-nonadecenoate (17) resulting from the reaction of n-Bu3SnH with methyl 3(RS)-methyl-18-nonadecynoate (16). Methyl branching was introduced at an early stage by Friedel-Crafts acylation of thiophene with 3(RS)-methyl-4-carbomethoxybutanoyl chloride (3) generated from 3-methylglutaric anhydride. The new agent, [125I]-19, showed high myocardial uptake (5 min, 4.89% dose/g; 30 min, 3.32% dose/g), good heart/blood (H/B) ratios (5 min, 5.4/1; 30 min, 4.3/1), and significantly greater myocardial retention in fasted rats than the corresponding straight-chain analogue 19-[125I]-iodo-18-nonadecenoic acid (5 min, 3.52% dose/g, H/B = 4.8/1; 30 min, 1.19% dose/g, H/B = 1.6/1). Excellent myocardial images were obtained in rats after administration of [123I]-19 and confirmed the slow myocardial washout over a 60-min period. These data suggest that 19 is a good candidate for evaluation of heart disease involving aberrations in fatty acid metabolism by use of imaging techniques such as single photon emission computerized tomography (SPECT) where redistribution or washout should be minimized.

Synthesis and evaluation of radioiodinated (E)-18-iodo-17-octadecenoic acid as a model iodoalkenyl fatty acid for myocardial imaging.

125I-labeled (E)-18-iodo-17-octadecenoic acid (13) has been prepared and evaluated in rats to determine the myocardial uptake and retention and degree of in vivo deiodination of this model iodovinyl-substituted fatty acid, which contains no structural perturbation to inhibit metabolism. This new agent was prepared by NaI-chloramine-T treatment of (17-carbomethoxyheptadec-1-en-1-yl)boronic acid (11) prepared by catecholborane treatment of methyl 17-octadecynoate (10), followed by basic hydrolysis to the free acid (13). The pivotal substrate, 17-octadecynoic acid (9), was prepared by two new routes. The 125I-labeled acid 13 showed high myocardial uptake (1 h, 1.90-2.28% dose/g) with 45% washout after 2 h but lower heart/blood ratios in comparison to analogues containing the tellurium heteroatom. Deiodination was low for the first 2 h after injection (2 h, 61% dose/g). Excellent myocardial images were obtained in a dog with the 123I-labeled agent.