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Biomedical subjects

T M Wilson

Publications and source records attributed to T M Wilson.

At least 19 recordsLinked to original sources
PubMed1992

The localization, partial purification and regulation of pea plastid HMG-CoA reductase.

HMG-CoA reductase was located to the envelope membranes of pea etioplasts, the first report of the suborganelle localization of this key enzyme in isoprenoid synthesis. The enzyme was purified 156 fold from isolated envelope membranes. Purification was achieved by detergent solubilization, hydroxylapatite chromatography and glycerol gradient centrifugation. Membrane-bound etioplast HMG-CoA reductase was activated 4 to 5 fold by high concentrations of inorganic phosphate, this activation was prevented by arsenate, a structural analog of phosphate.

Arsenates↗
PubMed1992

A review and update of animal toxicoses associated with fumonisin-contaminated feeds and production of fumonisins by Fusarium isolates.

During the 1989 corn harvest season, numerous reports of equine leukoencephalomalacia (ELEM) outbreaks and a pulmonary edema (PPE) syndrome in swine from several regions of the United States were received by the National Veterinary Services Laboratories (NVSL), Ames, Iowa. Previous and concurrent research linked Fusarium moniliforme and fumonisin-contaminated feeds to both diseases. Chemical and mycological investigations revealed fumonisin B1 (FB1) concentrations of 20 to 360 ppm in suspect swine feeds and 8 to 117 ppm in suspect equine feeds. Nonproblem feeds contained concentrations below 8 ppm. Fusarium moniliforme and Fusarium proliferatum were isolated from both problem and nonproblem equine and swine feeds. When cultured on autoclaved corn, the F. moniliforme and F. proliferatum isolated produced respective FB1 and fumonisin B2 (FB2) that range from less than 5 to more than 2450 ppm and less than 5 to more than 1000 ppm, respectively. Isolates from both problem and nonproblem feeds produces high levels (greater than 500 ppm) in culture. Reported here is a review of chemical and mycological data resulting from the study of several cases of PPE and ELEM.

Animal Feed↗
PubMed1992

Experimental reproduction of ELEM. A study to determine the minimum toxic dose in ponies.

An experiment to gain insight into the minimum toxic dose of fumonisins was conducted by feeding ponies rations with known fumonisin concentrations. Naturally contaminated corn screenings (CS) were blended with pellets, corn, and molasses to formulate individual daily diets. One group of 4 ponies was fed a ration with fumonisin B1 (FB1) varying from less than 1 ppm to 22 ppm. A second group of 5 ponies was fed a ration at varying rates containing 8 ppm FB1 for 180 days. A panel of clinical chemistry parameters was evaluated twice weekly for both groups. One pony in the first group died of equine leukoencephalomalacia (ELEM) after 225 days of which the final 55 days' diet contained 22 ppm FB1. Approximately 9 days prior to death, this animal experienced elevated liver chemistry values. All 5 ponies in the second group experienced mild, transient, clinical signs; were euthanized at 180 days; and had mild, histopathological brain lesions.

Animal Feed↗
PubMed1992

Increases in serum sphingosine and sphinganine and decreases in complex sphingolipids in ponies given feed containing fumonisins, mycotoxins produced by Fusarium moniliforme.

Consumption of food contaminated with Fusarium moniliforme causes leucoencephalomalacia and hepatotoxicity in horses, pulmonary edema in pigs and liver cancer in rats, and has been correlated with esophageal cancer in humans. The causative agents are thought to be a family of compounds called fumonisins, which have recently been shown to be potent inhibitors of sphingosine (sphinganine) N-acyltransferase. Because inhibition at this step blocks the formation of complex sphingolipids while leading to accumulation of sphinganine, we hypothesized that exposure of animals to fumonisin-contaminated feed might be detected by analyses of serum sphingolipids. Within days of giving ponies feed contaminated with 15 to 44 micrograms/g fumonisin B1, there was an increase in the amount of free sphinganine (and sometimes sphingosine) and a reduction in complex sphingolipids. Free sphinganine and sphingosine decreased when ponies consumed less of the contaminated feed, and increased again when they consumed more fumonisin. When toxicosis was evident as indicated by other serum markers, complex sphingolipids as well as free sphingosine and sphinganine were elevated, probably due to loss of sphingolipids from dying cells. These findings establish that consumption of fumonisin-contaminated feed disrupts sphingolipid metabolism. Because the changes in sphinganine and sphingosine were seen before liver enzymes were noticeably elevated, they may be an early marker of exposure to fumonisins.

Animal Feed↗
PubMed1992

Characterization of an epizootic of pulmonary edema in swine associated with fumonisin in corn screenings.

In 1989, corn screenings were associated with acute interstitial pulmonary edema, hydrothorax, and death in swine. Attack rate was 5-50%, case fatality rate was 50-90%, and clinical course was 1-2 days. Screenings from farms with pigs affected with pulmonary edema contained 20-330 micrograms fumonisin B1 per gram. Screenings containing 92 micrograms fumonisin B1 per gram fed to weanling pigs caused pulmonary edema and death. Sterilized corn inoculated with Fusarium moniliforme and diluted 1:1 with clean corn contained fumonisin B1 (17 micrograms/g) and caused acute pulmonary edema when fed for 5 days. Survivors developed subacute hepatotoxicosis with individual hepatocellular necrosis, hepatomegalocytosis, and increased numbers of mitotic figures. Similar liver lesions occurred in pigs given fumonisin B1 intravenously at 0.8 mg/kg body weight for 14 days.

Animal Feed↗
PubMed1991

Familial combined hyperlipidaemia linked to the apolipoprotein AI-CII-AIV gene cluster on chromosome 11q23-q24.

Familial combined hyperlipidaemia (FCHL) is a common inherited disorder of lipid metabolism with a prevalence of 0.5-2.0% (refs 1, 2). It is estimated to cause 10% of premature coronary heart disease. The underlying metabolic and genetic defects in FCHL have not been identified, but a population study has suggested an association between FCHL and an XmnI restriction fragment length polymorphism (RFLP) within the apolipoprotein AI-CIII-AIV gene cluster. Here we confirm this association and show that it results from linkage disequilibrium between FCHL and the 6.6-kilobase (kb) allele of the XmnI RFLP. Subsequent analysis in seven FCHL families, ascertained through a proband carrying the 6.6 kb XmnI allele, demonstrated linkage to the AI-CIII-AIV cluster on 11q23-q24, zeta = 6.86 with no recombinants. This assignment will facilitate the identification of the mutation that causes hyperlipidaemia in these families.

Apolipoprotein A-I↗
PubMed1991

Concentrations of fumonisin B1 in feeds associated with animal health problems.

Ninety-eight samples of feeds associated with 44 cases of equine leukoencephalomalacia (ELEM) and 83 samples of feed associated with 42 cases of a porcine pulmonary edema syndrome (PPE) were analyzed for fumonisin B1 (FB1). For comparison purposes, 51 feed samples not associated with PPE or ELEM were also analyzed. Feed associated with ELEM contained FB1 ranging from less than 1 microgram/g to 126 micrograms/g with 75% of the cases having at least 1 sample above 10 micrograms/g. Feeds associated with PPE ranged from less than 1 microgram/g to 330 micrograms/g with 71% of the cases having at least 1 sample greater than 10 micrograms/g. Quantitation was by high performance liquid chromatography (HPLC)/fluorescence using the fluorescamine derivative with confirmation by thin layer chromatography (TLC) and/or gas chromatography/mass spectroscopy (GC/MS).

Animal Feed↗
PubMed1991

Complete uncoating of the 5' leader sequence of tobacco mosaic virus RNA occurs rapidly and is required to initiate cotranslational virus disassembly in vitro.

Destabilizing events required for subsequent cotranslational disassembly of tobacco mosaic virus (TMV) particles in vitro were studied. Brief treatment of U-32P-labelled TMV (strain vulgare or U2) with 1% SDS exposed only 2.5% of the RNA (160 5' nucleotides) in a susceptible subpopulation of virions. Limited uncoating occurred almost immediately and appeared to be synchronous because the amount of 5' oligonucleotide marker (omega) recovered remained constant throughout a 15 min period in SDS. Additional RNase T1-sensitive oligonucleotides were exposed only after 1 to 2 min in SDS. Coat protein (CP) subunits released from virions 'destabilized' by ultracentrifugation at between pH 7.2 and 9.2 were quantified using L-[35S]methionine-labelled particles of TMV strain U2. CP recovery and virus particle translation results were consistent with increasing numbers of virions uncoating for approximately 200 nucleotides. In the presence of sparsomycin (SPN), the TMV strain vulgare 5' leader and the first AUG codon can bind two 80S ribosomes. Electron microscopy of pH 7.5-treated TMV particles incubated in SPN-treated wheatgerm extract or rabbit reticulocyte lysate, showed that approximately 10% of virions complexed with one ribosome and approximately 10% with two bound ribosomes, confirming that omega at least had been uncoated. Nucleocapsids in these complexes were shorter than untreated TMV by 9 to 10 nm (i.e. equivalent to 192 to 217 nucleotides exposed). The template activities of virions pretreated at pH 7.2 to 9.2 were destroyed by RNase H when short cDNAs were hybridized to sequences at, or immediately 3' to, the first AUG codon. We propose that the complete 5' leader of TMV RNA interacts weakly with CP subunits and that this micro-instability is due to the absence of G residues and is essential for initiation of cotranslational virus disassembly.

Base Sequence↗
PubMed1991

Salicylic acid is a systemic signal and an inducer of pathogenesis-related proteins in virus-infected tobacco.

Systemic induction of pathogenesis-related (PR) proteins in tobacco, which occurs during the hypersensitive response to tobacco mosaic virus (TMV), may be caused by a minimum 10-fold systemic increase in endogenous levels of salicylic acid (SA). This rise in SA parallels PR-1 protein induction and occurs in TMV-resistant Xanthi-nc tobacco carrying the N gene, but not in TMV-susceptible (nn) tobacco. By feeding SA to excised leaves of Xanthi-nc (NN) tobacco, we have shown that the observed increase in endogenous SA levels is sufficient for the systemic induction of PR-1 proteins. TMV infection became systemic and Xanthi-nc plants failed to accumulate PR-1 proteins at 32 degrees C. This loss of hypersensitive response at high temperature was associated with an inability to accumulate SA. However, spraying leaves with SA induced PR-1 proteins at both 24 and 32 degrees C. SA is most likely exported from the primary site of infection to the uninfected tissues. A computer model predicts that SA should move rapidly in phloem. When leaves of Xanthi-nc tobacco were excised 24 hr after TMV inoculation and exudates from the cut petioles were collected, the increase in endogenous SA in TMV-inoculated leaves paralleled SA levels in exudates. Exudation and leaf accumulation of SA were proportional to TMV concentration and were higher in light than in darkness. Different components of TMV were compared for their ability to induce SA accumulation and exudation: three different aggregation states of coat protein failed to induce SA, but unencapsidated viral RNA elicited SA accumulation in leaves and phloem. These results further support the hypothesis that SA acts as an endogenous signal that triggers local and systemic induction of PR-1 proteins and, possibly, some components of systemic acquired resistance in NN tobacco.

Immunity, Innate↗
PubMed1991

Multiplication of Legionella spp. in tap water containing Hartmannella vermiformis.

A model was developed to study the multiplication of various Legionella spp. in tap water containing Hartmannella vermiformis. Tap water cultures prepared with the following components were suitable for the multiplication studies: Legionella spp., 10(3) CFU/ml; H. vermiformis, 10(4.4) cysts per ml; and killed Pseudomonas paucimobilis, 10(9) cells per ml. Cocultures were incubated at 37 degrees C for at least 1 week. The following legionellae multiplied in tap water cocultures in each replicate experiment: L. bozemanii (WIGA strain), L. dumoffii (NY-23 and TX-KL strains), L. micdadei (two environmental strains), and L. pneumophila (six environmental strains and one clinical isolate). Growth yield values for these strains were 0.6 to 3.5 log CFU/ml. Legionellae which did not multiply in replicate cocultures included L. anisa (one strain), L. bozemanii (MI-15 strain), L. micdadei (a clinical isolate), L. longbeachae, (one strain), and L. pneumophila (Philadelphia 1 strain). L. gormanii and an environmental isolate of L. pneumophila multiplied in only one of three experiments. None of the legionellae multiplied in tap water containing only killed P. paucimobilis. The mean growth yield (+/- standard deviation) of H. vermiformis in the cocultures was 1.2 +/- 0.1 log units/ml. H. vermiformis supports multiplication of only particular strains of legionellae, some of which are from diverse origins.

Animals↗
PubMed1991

Fumonisin B1 concentrations in feeds from 45 confirmed equine leukoencephalomalacia cases.

During the fall of 1989 and winter of 1990, numerous reports of equine leukoencephalomalacia (ELEM) occurred from many regions of the United States. Typically, horses were consuming feed partially or entirely composed of corn and/or corn screenings. From October 1989 through May 1990, samples from 55 confirmed or suspected ELEM cases were received at the National Veterinary Services Laboratories, Ames, Iowa, for fumonisin B1 analysis. Samples from 9 cases in 1984-1985 were also obtained. Fumonisin B1, a mycotoxin produced by Fusarium moniliforme, causes ELEM, but little is known of naturally occurring toxic or safe levels in feeds. To determine what levels of fumonisin B1 in feeds are associated with ELEM, 45 selected cases were studied. The fumonisin B1 concentrations ranged from less than 1 ppm to 126 ppm, with the majority of the samples above 10 ppm. All types of feeds were included: corn, screenings, sweet feeds, and commercially pelleted rations. The length of exposure varied from 7 to greater than 35 days. Horse feed samples not associated with ELEM were also collected and analyzed. None of the nonproblem feed samples contained fumonisin B1 levels greater than 8 ppm.

Animal Feed↗
PubMed1991

Current status of transrectal ultrasonography in the detection of prostate cancer.

Transrectal ultrasonography is a new procedure for detecting prostate cancer. Better imaging of the prostate results in a better understanding of the appearance of prostate cancer and a heightened awareness of cancer location within the prostate. The appearance of malignancy frequently is a hypoechoic lesion, most often in the peripheral zone of the prostate. Biopsy of suspected areas of the prostate is also more accurate when done in conjunction with transrectal ultrasonography, which also allows evaluation of lesions not yet palpable on rectal examination. This has introduced the concepts of early detection and mass screening for prostate cancer. Although controversial and limited by low specificity, transrectal ultrasonography is a valuable addition for better detection of prostate cancer.

Humans↗
PubMed1990

Translation initiation factor-dependent extracts from Saccharomyces cerevisiae.

Translation initiation factor 4A- and 4E-dependent extracts were developed from Saccharomyces cerevisiae and used to study factor requirements for translation of individual mRNAs in vitro. Whereas all mRNAs tested required eIF-4A, mRNAs devoid of secondary structure in their 5' untranslated region did not require exogenous eIF-4E for translation. The latter included alfalfa mosaic virus RNA4, mRNA containing the untranslated region of tobacco mosaic virus RNA and mRNA containing part of the untranslated region of poliovirus RNA. Furthermore, initiation of translation on mRNAs containing part of the untranslated region of poliovirus RNA is most likely internal.

Animals↗
PubMed1990

The 5'-leader sequence of tobacco mosaic virus RNA mediates initiation-factor-4E-independent, but still initiation-factor-4A-dependent translation in yeast extracts.

Messenger RNAs encoding chloramphenicol acetyltransferase (CAT) with or without the 5'-leader sequence of tobacco mosaic virus (TMV) RNA were synthesized in vitro and translated in Saccharomyces cerevisiae extracts dependent on eukaryotic initiation factors eIF-4E or eIF-4A. The 5'-leader sequence of TMV RNA renders translation of CAT mRNA eIF-4E-independent but still 4A-dependent.

Chloramphenicol O-Acetyltransferase↗