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Biomedical subjects

T M Wilson

Publications and source records attributed to T M Wilson.

At least 55 records · Page 3Linked to original sources
PubMed1994

Detection and sequence analysis of a spontaneous deletion mutant of soil-borne wheat mosaic virus RNA2 associated with increased symptom severity.

Repeated passage of soil-borne wheat mosaic virus (SBWMV; wild-type Oklahoma field isolate; designated Okl-0) by manual inoculation resulted in deletion of part of SBWMV RNA2. Deletion was apparent in the population of RNA2 molecules after only 11 weeks in primary inoculated wheat plants (called Okl-1) and after 5 passages (Okl-5; 20 weeks) no full-length RNA2 remained. The extent of deletion in the Oklahoma isolate was compared with that in the previously studied Lab 1 (Nebraska) isolate. RNA2 from Okl-1, Okl-7, and Lab 1 were analyzed by RT-PCR amplification using sets of primer pairs which spanned all portions of the intact molecule. Lab 1 and the new stable isolate, Okl-7, were found to be deleted for 1058 and 759 nt, respectively, within the region encoding the coat protein-readthrough domain. However, the Okl-7 deletion was in a different position from the Lab 1 deletion. This suggests that deletions of SBWMV RNA2 which occur during serial manual inoculation are not directed toward production of a conserved, truncated form of the 84-kDa extended coat protein, but might reflect an RNA sequence-dependent event.

Amino Acid Sequence↗
PubMed1994

Assembly of tobacco mosaic virus and TMV-like pseudovirus particles in Escherichia coli.

High-level expression of plant viral proteins, including coat protein (CP), is possible in Escherichia coli. Native tobacco mosaic virus (TMV) CP expressed in E. coli remains soluble but has a non-acetylated N-terminal Ser residue and following extraction, is unable to package TMV RNA in vitro under standard assembly conditions. Changing the Ser to Ala or Pro by PCR-mutagenesis did not confer assembly competence in vitro, despite these being non-acetylated N-termini present in two natural strains of TMV. All TMV CPs made in E. coli formed stacked cylindrical aggregates in vitro at pH 5.0 and failed to be immunogold-labelled using a mouse monoclonal antibody specific for helically assembled TMV CP. TMV self-assembly has been studied extensively in vitro, and an origin of assembly sequence (OAS) mapped internally on the 6.4 kb ssRNA genome. Pseudovirus particles can be assembled mono- or bi-directionally in vitro using virus-derived CP and chimeric ssRNAs containing the cognate TMV OAS, but otherwise of unlimited length and sequence. Studies on plant virus assembly in vivo would be facilitated by a model system amenable to site-directed mutagenesis and rapid recovery of progeny particles. When chimeric transcripts containing the TMV OAS were co-expressed with TMV CP in vivo for 2-18 h, helical TMV-like ribonucleoprotein particles of the predicted length were formed in high yield (up to 7.4 micrograms/mg total bacterial protein). In addition to providing a rapid, inexpensive and convenient system to produce, protect and recover chimeric gene transcripts of any length or sequence, this E. coli system also offers a rapid approach for studying the molecular requirements for plant virus "self-assembly" in vivo. Transcription of a full-length cDNA clone of TMV RNA also resulted in high levels of CP expression and assembly of sufficient intact genomic RNA to initiate virus infection of susceptible tobacco plants.

Capsid↗
PubMed1994

Replacement of a conserved glycine residue in subunit II of cytochrome c oxidase interferes with protein function.

In this paper we describe the isolation and characterization of a respiration-deficient yeast strain which is defective in the function of subunit II of cytochrome c oxidase. This strain, VC32, carries a mutation in the mitochondrial COX2 gene which converts a conserved glycine residue to arginine. The conserved glycine is in a region implicated as important for ligating the CuA redox center and for interaction with cytochrome c. We have also characterized five revertants of VC32 which have recovered respiratory function; all five were mapped to the mitochondrial genome. In three of the five revertants the wild-type glycine codon is restored, while in two of the five the mutant arginine codon is still present. These two strains are likely to possess alterations either in components of the mitochondrial translation machinery or in mitochondrially-encoded gene products that interact directly with subunit II to assemble an active oxidase complex.

Amino Acid Sequence↗
PubMed1994

Acute ethanol exposure suppresses the repair of O6-methylguanine DNA lesions in castrated adult male rats.

Alcohol has clearly been associated with an increase of cancers in numerous tissue, including the respiratory tract, colon, rectum, liver, but especially the esophagus, larynx, pharynx, and mouth. Alcohol alone has not been shown to be a mutagen until it is converted to acetaldehyde and, therefore, alcohol presumably acts as a cocarcinogen. Previous data has shown that alcohol concentrations of 2% or greater inhibits DNA repair, and in light of the widespread consumption of alcoholic beverages with alcohol contents ranging from 4 to 5% (beer and wine coolers) to 50% (whiskey), interest in determining the mechanism(s) responsible for alcohol-induced carcinogenesis has heightened. Although previous studies, in intact rats, have investigated the effects of chronic alcohol exposure on some aspects of DNA repair, we have begun to address the effects of acute or "binge" alcohol exposure on mammalian DNA repair. Toward this end, we report the inhibition of O6-methylguanine-DNA methyltransferase (MGMT) by a single intraperitoneal injection of 30% ethanol in adult male castrated rats. This inhibition lasted for at least 24 hr. We also observed a dose-response effect of ethanol on MGMT activity, again only in the castrated rats. The finding of ethanol's effect on MGMT activity in castrated and not intact rats implies a hormonal component of MGMT DNA repair response, which has only been alluded to in past research.

Animals↗
PubMed1993

Strategies to protect crop plants against viruses: pathogen-derived resistance blossoms.

Since 1986, the ability to confer resistance against an otherwise devastating virus by introducing a single pathogen-derived or virus-targeted sequence into the DNA of a potential host plant has had a marked influence on much of the research effort, focus, and short-term objectives of plant virologists throughout the world. The vast literature on coat protein-mediated protection, for example, attests to our fascination for unraveling fundamental molecular mechanism(s), our (vain) search for a unifying hypothesis, our pragmatic interest in commercially exploitable opportunities for crop protection, and our ingenuity in manipulating transgene constructions to broaden their utility and reduce real or perceived environmental risk issues. Other single dominant, pathogen-derived plant resistance genes have recently been discovered from a wide variety of viruses and are operative in an ever-increasing range of plant species. Additional candidates seem limited only by the effort invested in experimentation and by our ingenuity and imagination. This review attempts to consider, in a critical way, the current state of the art, some exceptions, and some proposed rules. The final impression, from all the case evidence considered, is that normal virus replication requires a subtle blend of host- and virus-coded proteins, present in critical relative concentrations and at specific times and places. Any unregulated superimposition of interfering protein or nucleic acid species can, therefore, result in an apparently virus-resistant plant phenotype.

Agriculture↗
PubMed1993

Complete nucleotide sequence and organization of the bipartite RNA genome of soil-borne wheat mosaic virus.

The complete nucleotide sequences of RNAs 1 and 2 of soil-borne wheat mosaic virus (SBWMV), type member of the furovirus group, were determined. RNA 1 is 7099 nucleotides (nt) and encodes a 150-kDa protein from the 5' end region, the UGA termination codon of which can be partially read through to produce a 209-kDa protein, and a 37-kDa protein in the 3' end region. The C-terminal region of the 150-kDa protein contains an NTP-binding helicase motif and the readthrough region, an RNA polymerase motif, indicating that these two overlapping proteins may form an RNA replication complex similar to those of tobamo- and tobraviruses. The 37-kDa protein has sequence similarity with the cell-to-cell transport protein of dianthoviruses. RNA 2 is 3593 nt and, from the 5' end region, encodes the 19-kDa capsid protein, whose UGA termination codon can be partially suppressed to produce an 84-kDa readthrough protein and, at the 3' proximity, a 19-kDa protein which is rich in cysteine residues. The 28K (kilodaltons, as estimated by SDS-PAGE) protein, previously considered as another capsid readthrough product, is apparently initiated at an in-frame non-AUG codon upstream from the capsid protein gene. In both RNAs 1 and 2, the 5' terminus is capped, and the 3' untranslated region possibly forms internal consecutive pseudoknots as found in tobamovirus RNA as well as a terminal tRNA-like structure similar to tymovirus RNA. An amino acid sequence comparison of RNA replicase genes indicates that, phylogenetically, SBWMV belongs to a cluster formed by tobamo-, tobra-, and hordeiviruses. Differences in the 3' end structure and in the cell-to-cell movement protein, and the distant phylogeny of the RNA replicase genes of SBWMV and beet necrotic yellow vein virus, suggest that the furoviruses should be divided into at least two groups.

Amino Acid Sequence↗
PubMed1993

Plant viral leaders influence expression of a reporter gene in tobacco.

In order to optimise expression of a foreign protein in transgenic plants we investigated the potential benefits of including a viral untranslated leader sequence within a plant transformation vector. A variety of 5 leaders, including the tobacco mosaic virus (TMV) leader sequence and 31 nucleotides of the cauliflower mosaic virus (CaMV) 35S RNA leader, were compared. Viral leader constructs employing the 35S promoter and the reporter beta-glucuronidase (GUS) were tested by electroporation into tobacco mesophyll protoplasts and against a cointroduced chloramphenicol acetyl transferase (CAT) gene in transgenic tobacco leaves. In the transient assay system, GUS activities from the viral leaders were compared with those from either a short, random leader or a translational fusion of the CaMV 19S RNA ORF VI to GUS. A two- to-three-fold enhanced level of expression resulted when these leaders were substituted with either the 35S RNA or the TMV leader sequences. This enhancement was further increased, to four- to five-fold, by inclusion of four or seven of the bases from the 35S transcription initiation site adjacent to the TMV leader. In transgenic tobacco the improved GUS levels were maintained from constructs including either the TMV leader (eight-fold) or this sequence with the addition of the 35S transcription initiation site bases (ten-fold). A comparison of GUS enzyme amounts with GUS mRNA amounts, using the CAT gene as an internal standard, revealed that TMV leader-bearing mRNA was translated from four- to six-fold more efficiently than the random leader control.

Base Sequence↗
PubMed1993

Clinical Stage B0 or T1c prostate cancer: nonpalpable disease identified by elevated serum prostate-specific antigen concentration.

A retrospective study was performed to evaluate the clinical and pathologic characteristics of 60 patients with a palpably benign prostate gland, but with biopsy-proved prostate cancer. All patients underwent prostate biopsy because of elevated serum prostate-specific antigen (PSA) concentration, and subsequently underwent radical retropubic prostatectomy (RRP). Similar analysis was performed for a randomly selected group of 60 clinical Stage B1 prostate cancers from the same period (control cohort). Patients with nonpalpable prostate cancers had a higher preoperative PSA level as compared with the clinical Stage B1 group (median value: 12.3 ng/mL versus 4.6 ng/mL, p < 0.001). There was no significant difference between the two groups with regard to clinical parameters (voiding symptoms, hematuria, age). The nonpalpable prostate cancers exhibited a significant tumor volume (mean: 7.4 cc; range: 0.3-56 cc), and 18 (30%) demonstrated capsular perforation to involve the periprostatic tissues. Of these, three (5%) had seminal vesicle invasion, and one (2%) had pelvic lymph node involvement. There was no difference between these pathologic characteristics and those of the clinical Stage B1 prostate cancers. These findings suggest that nonpalpable prostate cancers identified by an elevated serum PSA level can be of clinical significance and warrant therapeutic consideration. Although nonpalpable, these cancers are peripherally located and were clinically suspected prior to biopsy. Therefore, we propose that these cancers be classified as clinical Stage B0 in the Whitmore-Jewett staging system; in the new TNM staging system, they are designated as clinical Stage T1c.

Adult↗
PubMed1993

Biopsy-proved prostate cancer in 100 consecutive men with benign digital rectal examination and elevated serum prostate-specific antigen level. Prevalence and pathologic characteristics.

To determine whether a significant percentage of patients with a benign digital rectal examination (DRE) and an elevated serum prostate-specific antigen (PSA) level harbor a prostatic malignancy, 100 consecutive patients underwent transrectal ultrasound (TRUS)-guided biopsy of the prostate. The biopsy results were correlated with the pre-biopsy serum PSA level and ultrasound findings. Overall, the cancer detection rate was 35 percent (S.E. 4.8%). When the biopsy results were analyzed according to the PSA level, the rate of cancer detection increased with advancing PSA levels, irrespective of ultrasound findings. In the 60 patients with ultrasound abnormalities, the cancer detection rate was 47 percent compared with 18 percent for those without ultrasound abnormalities. Comparison of TRUS-negative and TRUS-positive biopsy results revealed a more than two-fold increase in cancer detection for the TRUS-positive group in each PSA range. Cancer detection in the TRUS-positive, PSA 4.1-10, 10.1-20.0, and > 20 ng/mL groups was 40 percent, 56 percent, and 67 percent, respectively; in the TRUS-negative group, cancer detection was 12 percent, 27 percent, and 33 percent, respectively. Twenty (57%) of the patients with prostate cancer underwent radical retropubic prostatectomy. The mean tumor volume was 4.7 cc. Seventy percent had organ-confined disease, 30 percent demonstrated capsular penetration only, and no patients had seminal vesicle or pelvic lymph node invasion. These data indicate that a significant percentage of patients with a benign DRE and an elevated serum PSA value harbor a clinically significant, but potentially curable prostatic malignancy.

Adenocarcinoma↗
PubMed1993

Clinical evaluation of antibiotic-supplemented bone allograft.

Antibiotic-supplemented bone allograft (ASBA) was originally developed for treatment of combat-acquired, avulsive defects of the oral and maxillofacial skeleton. Earlier findings in experimental wound models showed that ASBA resulted in significantly improved wound repair of infected osseous defects when compared with conventional treatment. In this study, ASBA was evaluated in paired, comparable, mandibular third molar sockets and compared with the findings following conventional surgical removal. The results of this assessment showed that wound healing was significantly improved with the use of ASBA. Evidence produced by this clinical evaluation of ASBA suggests its potential use for other surgical bone defects when grafting is precluded by the risk of infection as a result of contamination by oral flora.

Adult↗
PubMed1993

Experimental equine leukoencephalomalacia, toxic hepatosis, and encephalopathy caused by corn naturally contaminated with fumonisins.

A study to evaluate the effects of dietary fumonisin B1 was conducted using 6 ponies (4 test and 2 control). A ration naturally contaminated with fumonisin B1 was fed in 3 phases: 1) 44 ppm fumonisin B1, 2) less than 1 ppm fumonisin B1, and 3) 88 ppm fumonisin B1. All ponies were monitored daily, weighed weekly, and limit fed at a rate of 0.8% body weight plus hay. Feed intake was measured daily, and a serum chemistry panel was completed once or twice weekly. Four to 7 days after initiation of the trial (Phase 1), all 4 test ponies had decreased feed consumption, and selected serum chemistry parameters were markedly elevated. On day 9, 1 pony died acutely with mild encephalopathy and hepatic necrosis. Another pony, euthanized on day 45, also had mild encephalopathy and hepatic necrosis. The remaining 2 test ponies continued the 44 ppm fumonisin B1 diet for 98 days. Phase 2 consisted of a diet with < 1 ppm fumonisin B1 for 120 days. During this phase, the serum chemistry values of the 2 ponies returned to normal. Following Phase 2, the 2 ponies were fed a diet containing 88 ppm fumonisin B1. After 75 days, 1 animal died of equine leukoencephalomalacia with mild hepatic necrosis. On day 78, the remaining pony was euthanized after showing distress; it also had leukoencephalomalacia and hepatic lesions.

Animal Feed↗
PubMed1993

Effects of fumonisin-contaminated corn screenings on growth and health of feeder calves.

Fumonisins are myocotoxins produced by Fusarium moniliforme and F. proliferatum, common molds of corn in North America. The toxin is at especially high concentrations in corn screenings. Fumonisins are toxic to swine and horses, but effects of these toxins in cattle have not been evaluated. This experiment was conducted to determine the effects in cattle of feeding fumonisins at levels known to be toxic to swine and horses. A total of 18 crossbred feeder calves were fed diets containing fumonisins at 15, 31, or 148 micrograms/g for 31 d. Feed consumption, weight gain, complete blood count, serum clinical chemistries, and an immune function profile were done on d -3, 4, 10, 17 and 31 relative to the start of fumonisin feeding. There was no treatment-related effect on feed intake or weight gain, but feed containing 148 micrograms/g of fumonisins seemed to be less palatable than other feeds. Significant increases in serum aspartate amino transferase, gamma glutamyl transpeptidase, lactate dehydrogenase, bilirubin, and cholesterol occurred from d 10 through 31. Mild microscopic liver lesions were present in two calves fed at the highest fumonisin level. Lymphocyte blastogenesis was significantly impaired at the end of the feeding period in the group given the highest dose. Other measures of immune function were not affected significantly. Fumonisins are capable of causing changes in liver function and in some measures of immune function. However, cattle seem to be relatively less susceptible to fumonisins present naturally in grains than either swine or horses.

Animal Feed↗
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↗