Biomedical subjects

Dale R Gardner

Publications and source records attributed to Dale R Gardner.

13 recordsLinked to original sources

PubMed2006

Alkaloid profiles, concentration, and pools in velvet lupine (Lupinus leucophyllus) over the growing season.

Lupinus leucophyllus is one of many lupine species known to contain toxic and/or teratogenic alkaloids that can cause congenital birth defects. The concentrations of total alkaloids and the individual major alkaloids were measured in three different years from different plant parts over the phenological development of the plant. All of the alkaloids were found in the different plant tissues throughout the growing season, although their levels varied in different tissues. Concentrations of total alkaloids and the individual alkaloids varied on an annual basis and in their distribution in the different tissues. Anagyrine levels were highest in the floral tissue, lupanine and unknown F accumulated to the greatest level in the vegetative tissue, and 5,6-dehydrolupanine accumulated to the highest level in the stem. These alkaloids appear to be in a metabolically active state with the teratogenic alkaloid anagyrine accumulating to its highest level in the developing seed. The latter is, thus, the phenological stage posing the greatest danger to grazing livestock.

Alkaloids↗

PubMed2006

Study of biochemical pathways and enzymes involved in pyrene degradation by Mycobacterium sp. strain KMS.

Pyrene degradation is known in bacteria. In this study, Mycobacterium sp. strain KMS was used to study the metabolites produced during, and enzymes involved in, pyrene degradation. Several key metabolites, including pyrene-4,5-dione, cis-4,5-pyrene-dihydrodiol, phenanthrene-4,5-dicarboxylic acid, and 4-phenanthroic acid, were identified during pyrene degradation. Pyrene-4,5-dione, which accumulates as an end product in some gram-negative bacterial cultures, was further utilized and degraded by Mycobacterium sp. strain KMS. Enzymes involved in pyrene degradation by Mycobacterium sp. strain KMS were studied, using 2-D gel electrophoresis. The first protein in the catabolic pathway, aromatic-ring-hydroxylating dioxygenase, which oxidizes pyrene to cis-4,5-pyrene-dihydrodiol, was induced with the addition of pyrene and pyrene-4,5-dione to the cultures. The subcomponents of dioxygenase, including the alpha and beta subunits, 4Fe-4S ferredoxin, and the Rieske (2Fe-2S) region, were all induced. Other proteins responsible for further pyrene degradation, such as dihydrodiol dehydrogenase, oxidoreductase, and epoxide hydrolase, were also found to be significantly induced by the presence of pyrene and pyrene-4,5-dione. Several nonpathway-related proteins, including sterol-binding protein and cytochrome P450, were induced. A pyrene degradation pathway for Mycobacterium sp. strain KMS was proposed and confirmed by proteomic study by identifying almost all the enzymes required during the initial steps of pyrene degradation.

Bacterial Proteins↗

PubMed2006

Temporal and spatial variation in alkaloid levels in Achnatherum robustum, a native grass infected with the endophyte Neotyphodium.

The native North American perennial grass Achnatherum robustum (Vasey) Barkworth [= Stipa robusta (Vasey) Scribn.] or sleepygrass is toxic and narcotic to livestock. The causative agents are alkaloidal mycotoxins produced from infections by a systemic and asexual Neotyphodium endophyte. Recent studies suggest that toxicity is limited across the range of sleepygrass in the Southwest USA. We sampled 17 populations of sleepygrass with varying distance from one focal population known for its high toxicity levels near Cloudcroft, NM, USA. For some, we sampled individual plants twice within the same growing season and over successive years (2001-2004). We also determined infection levels in each population. In general, all populations were highly infected, but infection levels were more variable near the focal population. Only infected plants within populations near the Cloudcroft area produced alkaloids. The ergot alkaloid, ergonovine, comprised the bulk of the alkaloids, with lesser amounts of lysergic and isolysergic acid amides and ergonovinine alkaloids. Levels of all alkaloids were positively correlated among individual plants within and between growing seasons. Infected plants that produced no alkaloids in 1 yr did not produce any alkaloids within the same growing season or in other years. Levels of alkaloids in sleepygrass populations declined with distance from the Cloudcroft population, although infection levels increased. Infected plants in populations in northern New Mexico and southern Colorado produced no alkaloids at all despite 100% infectivity. Our results suggest that only specific Neotyphodium haplotypes or specific Neotyphodium-grass combinations produce ergot alkaloids in sleepygrass. The Neotyphodium haplotype or host-endophyte combination that produces toxic levels of alkaloids appears restricted to one locality across the range of sleepygrass. Because of the wide variation in alkaloid levels among populations, interactions between the endophyte and host, and consequences for herbivores, competitors, and pathogens and other components of the community, are likely to vary widely across the geographic range of this native grass.

Alkaloids↗

PubMed2006

Relative toxicities and neuromuscular nicotinic receptor agonistic potencies of anabasine enantiomers and anabaseine.

Anabasine occurring in wild tree tobacco (Nicotiana glauca) and anabaseine occurring in certain animal venoms are nicotinic receptor agonist toxins. Anabasine lacks the imine double bond of anabaseine; the two possible enantiomers of anabasine occur in N. glauca. A comparision of the relative potencies of S- and R-anabasine has not been previously reported. We separated the enantiomers of anabasine by reaction of the racemic N. glauca natural product with 9-fluorenylmethoxycarbonyl-L-alanine (Fmoc-L-Ala-OH) to give diastereomers, which were separated by preparative reversed phase HPLC. The S- and R-anabasine enantiomer fractions were then obtained by Edman degradation. A mouse bioassay was used to determine the relative lethalities of S- and R-enriched anabasine enantiomers. The intravenous LD50 of the (+)-R-anabasine rich fraction was 11 +/- 1.0 mg/kg and that of the (-)-S-anabasine-rich fraction was 16 +/- 1.0 mg/kg. The LD50 of anabaseine was 0.58 +/- 0.05 mg/kg. Anabaseine was significantly more toxic in the mouse bioassay than S-anabasine (27-fold) and R-anabasine (18-fold). The relative agonistic potencies of these three alkaloids on human fetal nicotinic neuromuscular receptors were of the same rank order: anabaseine>>R-anabasine>S-anabasine.

Anabasine↗

PubMed2005

Ammodendrine and N-methylammodendrine enantiomers: isolation, optical rotation, and toxicity.

Ammodendrine (1) was found to occur as a mixture of enantiomers in two different collections of plants identified as Lupinus formosus. The ammodendrine fraction was reacted in a peptide coupling reaction with 9-fluorenylmethoxycarbonyl-L-alanine (Fmoc-L-Ala-OH) to give diastereomers, which were separated by preparative HPLC. The pure D- and L-ammodendrine enantiomers were then obtained by Edman degradation. Optical rotation measurements revealed that the D- and L-enantiomers had optical rotations of [alpha]24D +5.4 and -5.7, respectively. D- and L-N-methylammodendrine enantiomers were synthesized from the corresponding ammodendrine enantiomers, and their optical rotations established as [alpha]23D +62.4 and -59.0, respectively. A mouse bioassay was used to determine the difference in toxicity between these two pairs of naturally occurring enantiomers. The LD50 of (+)-D-ammodendrine in mice was determined to be 94.1 +/- 7 mg/kg and that of (-)-L-ammodendrine as 115.0 +/- 7 mg/kg. The LD50 of (+)-D-N-methylammodendrine in mice was estimated to be 56.3 mg/kg, while that of (-)-L-N-methylammodendrine was determined to be 63.4 +/- 5 mg/kg. These results establish the rotation values for pure ammodendrine and N-methylammodendrine and indicate that there is little difference in acute murine toxicity between the respective enantiomers.

Animals↗

PubMed2003

Development of enzyme-linked immunosorbent assays for isocupressic acid and serum metabolites of isocupressic acid.

The consumption of ponderosa pine (Pinus ponderosa), lodgepole pine (Pinus contorta), common juniper (Juniperus communis), and Monterey cypress (Cupressus macrocarpa) causes abortions in pregnant cattle. Recent studies have identified isocupressic acid (1) as the primary abortificient compound in these plants. In vitro and in vivo studies using rumen and blood have shown isocupressic acid (1) is rapidly metabolized to agathic acid (3), dihydroagathic acid (4), and tetrahydroagathic acid (5). Rapid and sensitive diagnostic techniques are needed to identify poisoned animals, to study toxicokinetics, and to elucidate the mechanism of isocupressic acid-induced abortion in cattle. In this study, four competitive inhibition enzyme-linked immunosorbent assays for isocupressic acid and its sera metabolites were developed using polyclonal antibodies. One assay is specific to 1, whereas the other three assays show cross-reactivity to 3-5 in addition to 1. The assay specific to 1 had a limit of detection of 44.1 pg. The other assays which demonstrated cross-reactivity to the isocupressic acid blood metabolites also had comparably low limits of detection. One assay was used to follow the absorption and elimination profile of isocupressic acid metabolites in both cow serum and urine after oral dosage of a cow with common juniper.

Abortifacient Agents↗

PubMed2003

Sites of phosphorylation of P and V proteins from Hendra and Nipah viruses: newly emerged members of Paramyxoviridae.

Hendra (HeV) and Nipah (NiV) viruses are newly emerged, zoonotic viruses and their genomes have nucleotide and predicted amino acid homologies placing them in the subfamily Paramyxoviridae. The polymerase-associated phosphoproteins (P proteins) of paramyxoviruses have been shown, by direct and indirect methods, to be highly phosphorylated. In this study, a comprehensive comparison of in vivo phosphorylation of HeV and NiV P proteins, derived from virus particles, was achieved by a direct approach using electrospray ionization ion trap mass spectrometry (ESI-IT-MS). Phosphorylation sites for the P proteins were determined at Ser-224 and Thr-239 in HeV and at Ser-240 and Ser-472 in NiV. These phosphorylation patterns do not appear to be consistent with those reported for other paramyxoviruses. Protein V, a product of a frame shift in the P protein gene, was identified by specific antibodies in HeV preparations but not in NiV. HeV V protein was found to contain phosphoserine but not phosphothreonine. In addition, P proteins from both viruses were found to be modified by N-terminal acetylation.

Amino Acid Sequence↗

PubMed2003

Catastrophic cattle loss to low larkspur (Delphinium nuttallianum) in Idaho.

Low larkspur (Delphinium nuttallianum) is a toxic plant found on many western US rangelands. Episodes of fatal poisoning are often related to the abundance and toxicity of the low larkspurs. This report documents the fatal intoxication of 53 cattle in a herd of 404 animals in south-central Idaho during Spring 2002. Low larkspur had a toxic alkaloid concentration of 8.26 mg/g. Several factors were involved in a loss of this magnitude, including climatic conditions ideal for low larkspur growth, poor grass growth during the spring, the high alkaloid concentration in larkspur, and the deaths of many cattle while being moved from the pasture. It is important for livestock owners and managers to recognize toxic plants growing in their area. If there is an unusual abundance of larkspur or other toxic plants, correct identification can provoke caution in grazing management.

Animals↗

PubMed2002

Polyhydroxy alkaloids: chromatographic analysis.

Polyhydroxy alkaloids are a burgeoning category of natural products that encompass several structural types and generally exhibit potent activity as inhibitors of glycosidases. As presently defined the group consists of monocyclic or bicyclic aLkaloids of the pyrrolidine, piperidine, pyrrolizidine, indolizidine and tropane classes, bearing two or more hydroxyl groups. These structural features render the compounds highly water soluble and frequently quite insoluble in non-hydroxylic solvents, so that their isolation and analysis by chromatographic means are consequently difficult. This problem is further confounded by the lack of a chromophore which would permit their detection by UV absorption. This review presents chromatographic techniques that have been successfully applied to the problem of isolating, purifying, detecting and analyzing polyhydroxy alkaloids.

Alkaloids↗

PubMed2002

Preparation of tetrahydroagathic acid: a serum metabolite of isocupressic acid, a cattle abortifacient in ponderosa pine.

Isocupressic acid (1) was used to synthetically prepare a mixture of (8S,13R,S)-labda-15,19-dioic acid (tetrahydroagathic acid) (5) via a two-step oxidation procedure followed by hydrogenation of the double bonds at C13 and C8. Reduction of the C8,17 double bond was stereospecific producing only the 8S isomer and confirmed by the nOe interaction between the resulting C17 and C20 methyl groups. The 13R and 13S isomers of 5 were separated and analyzed by HPLC/MS, and (13S)-tetrahydroagathic acid was isolated and identified by comparison to a standard prepared by hydrogenation of naturally occurring (13S)-dihydroagathic acid (4). (13R,S)-dihydroagathic acid was prepared by selective sodium metal-catalyzed hydrogenation of the C13,14 allylic double bond of agathic acid (3). The prepared compounds were then used as standards to confirm the presence of 4 and 5 and their respective 13R and 13S isomers in bovine serum samples. Tetrahydroagathic acid was shown to be the only metabolite detected in serum samples taken from a suspected cattle abortion case submitted for diagnosis; and, thus, 5 could be a valuable diagnostic marker for pine needle-induced abortions.

Abortifacient Agents↗

PubMed2002

Development of STS and CAPS markers for identification of three tall larkspurs (Delphinium spp.).

One cleaved amplified polymorphic sequence (CAPS) and nine sequence tagged site (STS) markers were developed for identifying tall larkspur (Delphinium spp.) plants in three species based on the DNA sequence of known species-specific RAPD markers. Four STS markers were used for identification of Delphinium occidentale, three STS markers for Delphinium barbeyi, and one CAPS and two STS markers for Delphinium glaucum. One hundred sixty-six individual plants collected at 19 locations in the western U.S.A. were tested using the STS and CAPS markers. Over 95% of the D. occidentale plants contained all four D. occidentale specific STS markers, whereas the remaining plants contained three of the four STS markers. Approximately 97% of D. barbeyi plants contained all three D. barbeyi specific STS markers, and the rest had two of the three STS markers. A small percentage of D. barbeyi plants contained one D. occidentale specific STS marker. Hybrid populations were characterized as having more D. occidentale specific than D. barbeyi specific STS markers, suggesting that the three hybrid populations are composed not of F1 hybrid plants of the parental species but of segregating offspring of different generations from original hybrids. This set of STS and CAPS markers for larkspur species should be useful in classification of unknown plant materials and the identification of hybrid populations.

Crosses, Genetic↗

PubMed2002

Identification of swainsonine as a glycoside inhibitor responsible for Sida carpinifolia poisoning.

The indolizidine alkaloid swainsonine has been identified as the toxic constituent of Sida carpinifolia, a native perennial shrub-like plant, reported to produce neurological disorders in goats and ponies in southern Brazil. Swainsonine was detected in dry ground plant material after extraction and analysis by both liquid and gas chromatography mass spectrometry. The swainsonine concentration was 0.006% on a dry weight basis. The clinical and pathological features of this lysosomal storage disease were similar to those observed in Swainsona, Oxytropis, Astragalus, and Ipomoea poisonings with multiple cytoplasm vacuoles in neurons, acinar pancreatic cells, hepatocytes, and renal tubular cells.

Animals↗

PubMedDate not supplied

Preparative isolation of swainsonine from locoweed: extraction and purification procedures.

The trihydroxy indolizidine alkaloid swainsonine, a plant toxin with potent alpha-mannosidase-inhibitory activity and chemotherapeutic potential, was isolated in gram quantities from locoweed (Astragalus lentiginosus). The key isolation and purification step was a continuous liquid/liquid extraction procedure using dichloromethane to extract a basified aqueous methanol solution obtained after isolation of the polar base fraction by ion-exchange. The concentration of swainsonine was increased from ca. 7% in the polar base material to 68% using the liquid/liquid extraction procedure. Pure swainsonine was then obtained by recrystallisation from ammonia-saturated chloroform or by sublimation. Small samples of swainsonine were also purified by formation of the chloroform-soluble methylboronate derivative, from which the alkaloid could be regenerated easily by hydrolysis.

Alkaloids↗