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Biomedical subjects

M Shanks

Publications and source records attributed to M Shanks.

At least 19 recordsLinked to original sources
PubMed2005

The use of viral vectors to produce hepatitis B virus core particles in plants.

The expression and assembly of the hepatitis B virus (HBV) nucleocapsid protein (HBcAg) were investigated in plants using viral vectors. Constructs based on either Potato virus X (PVX) or Cowpea mosaic virus (CPMV) containing the sequence of HBcAg were able to infect the appropriate host plants and remained genetically stable during infection. Analysis of HBcAg expression revealed that the protein can self-assemble into core-like particles and that the assembled material could be partially purified by differential centrifugation. Thus, the use of viral vectors can be considered a practical method for rapid production of assembled HBcAg particles in plants. This approach provides a means whereby a variety of chimaeric particles can be assessed quickly and cheaply for various diagnostic and vaccine applications.

Centrifugation↗
PubMed2005

Cochlear implantation and management of chronic suppurative otitis media: single stage procedure?

In a series of 360 patients who underwent cochlear implantation at our center, four patients (five procedures) had cochlear implantation with obliteration of the mastoid cavity and management of cholesteatoma as a single-staged procedure. Three patients were bilaterally deaf secondary to CSOM and had bilateral mastoid cavities, and in one patient congenital cholesteatoma was identified during cochlear implantation. A mastoidectomy or revision mastoidectomy with obliteration of the mastoid cavity and cochlear implantation was performed as a single stage procedure. Cholesteatoma reoccurred in one patient 9 years after cochlear implantation. Surgical procedures, complications, follow-up and outcomes are discussed.

Adult↗
PubMed2000

Use of palatal lift and palatal augmentation prostheses to improve dysarthria in patients with amyotrophic lateral sclerosis: a case series.

STATEMENT OF PROBLEM: Amyotrophic Lateral Sclerosis (ALS) is a progressive, adult onset neurodegenerative disorder manifesting itself as a loss of motor capabilities and untimely death. The dysarthria seen in patients with ALS who have bulbar symptoms causes severe problems with communication. The struggle to be understood comes at a time when progressive cumulative disabilities make communication with family, friends, and healthcare workers vital. The use of palatal lift/augmentation prostheses for dysarthria in ALS is not a frequently requested procedure by neurologists. PURPOSE: The purpose of this retrospective outcomes study was to evaluate the effectiveness of this treatment on improving speech function and intelligibility in this group of patients. This study also reviews the history, incidence, pathogenesis, and speech characteristics of the patient with ALS. METHODS: A retrospective study of 25 patients treated with a prosthesis was performed using chart reviews and phone/office interviews to evaluate the efficacy of a palatal lift and/or augmentation prosthesis to improve speech in ALS patients. RESULTS: Twenty-one patients (84%) treated with a palatal lift demonstrated improvement in their dysarthria, specifically in reduction of hypernasality, with 19 (76%) benefiting at least moderately for 6 months. Of the 10 patients treated with a combination palatal lift and augmentation prosthesis, 6 (60%) demonstrated improvement in articulation. A majority of patients indicated it was easier to speak with less effort involved when wearing the prosthesis. CONCLUSION: On the basis of this preliminary retrospective study, the use of a palatal lift/augmentation prosthesis should be considered in ALS patients with dysarthria.

Adult↗
PubMed2000

Association of phosphatidylinositol 3-kinase with nuclear transcription sites in higher plants.

The kinases responsible for phosphorylation of inositol-containing lipids are essential for many aspects of normal eukaryotic cell function. Genetic and biochemical studies have established that the phosphatidylinositol (PtdIns) 3-kinase encoded by the yeast VPS34 gene is essential for the efficient sorting and delivery of proteins to the vacuole; the kinase encoded by the human VPS34 homolog has been equally implicated in the control of intracellular vesicle traffic. The plant VPS34 homolog also is required for normal growth and development, and although a role for PtdIns 3-kinase in vesicle trafficking is likely, it has not been established. In this study, we have shown that considerable PtdIns 3-kinase activity is associated with the internal matrix of nuclei isolated from carrot suspension cells. Immunocytochemical and confocal laser scanning microscopy studies using the monoclonal antibody JIM135 (John Innes Monoclonal 135), raised against a truncated version of the soybean PtdIns 3-kinase, SPI3K-5p, revealed that this kinase appears to have a distinct and punctate distribution within the plant nucleus and nucleolus. Dual probing of root sections with JIM135 and anti-bromo-UTP antibodies, after in vitro transcription had been allowed to proceed in the presence of bromo-UTP, showed that SPI3K-5p associates with active nuclear and nucleolar transcription sites. These findings suggest a possible link between PtdIns 3-kinase activity and nuclear transcription in plants.

Cell Nucleus↗
PubMed2000

Structural fingerprinting: subgrouping of comoviruses by structural studies of red clover mottle virus to 2.4-A resolution and comparisons with other comoviruses.

Red clover mottle virus (RCMV) is a member of the comoviruses, a group of picornavirus-like plant viruses. The X-ray structure of RCMV strain S has been determined and refined to 2.4 A. The overall structure of RCMV is similar to that of two other comoviruses, Cowpea mosaic virus (CPMV) and Bean pod mottle virus (BPMV). The sequence of the coat proteins of RCMV strain O were modeled into the capsid structure of strain S without causing any distortion, confirming the close resemblance between the two strains. By comparing the RCMV structure with that of other comoviruses, a structural fingerprint at the N terminus of the small subunit was identified which allowed subgrouping of comoviruses into CPMV-like and BPMV-like viruses.

Amino Acid Sequence↗
PubMed1999

Studies on hybrid comoviruses reveal the importance of three-dimensional structure for processing of the viral coat proteins and show that the specificity of cleavage is greater in trans than in cis.

A series of cowpea mosaic virus (CPMV)-based hybrid comoviral RNA-2 molecules have been constructed. In these, the region encoding both the large (L) and small (S) viral coat proteins was replaced by the equivalent region from bean pod mottle virus (BPMV). The hybrid RNA-2 molecules were able to replicate in cowpea protoplasts in the presence of CPMV RNA-1. Though processing of the hybrid polyproteins by the CPMV-specific 24K proteinase at the site between the 58/48K and L proteins could readily be achieved, no processing at the site between the L and S coat proteins could be obtained even when the sequence of amino acids between the two coat proteins was made CPMV-like. As a result, none of the hybrids was able to form functional virus particles, and they could not infect cowpea plants. Comparison with the processing of the L-S site in cis in reticulocyte lysates demonstrated that the requirements for processing are more stringent in trans than in cis. The results suggest that the L-S cleavage site is defined by more than just a linear sequence of amino acids and probably involves interactions between the L-S loop and the beta barrels of the viral coat proteins.

Amino Acid Sequence↗
PubMed1997

The coat and cylindrical inclusion proteins of a potyvirus are associated with connections between plant cells.

The subcellular locations of two potyviral proteins, the coat (CP) and nonstructural cylindrical inclusion (CI) proteins of tobacco vein mottling virus (TVMV), during early stages in the development of systemic infections in plants, have been investigated. Ultrathin sections of newly emerged leaves in infected plants were treated with antibodies specific to these proteins and then with gold-labeled secondary antibodies and examined by electron microscopy. CI was detected near plasmodesmatal connections between mesophyll cells prior to the appearance of CP or any virus-induced features or effects. Further accumulation of CI was evident in the form of conical structures, many of which appeared to penetrate the cell wall and to be connected to cones in neighboring cells. Prior to its appearance in other parts of the cells, the viral CP was detected, often in linear arrays, near the vertices or inside the cones and in plasmodesmata. In situ hybridization analysis of similar tissue sections with a TVMV RNA-specific oligoribonucleotide probe revealed the presence of the viral RNA in plasmodesmata. These results lend support to the notion that the formation of specific structures by potyviral CI proteins is required for and plays a direct role in the intercellular passage of viral genetic material, in the form of virus particles or complexes containing viral CP and RNA, in infected plants.

Capsid↗
PubMed1997

Early-onset Alzheimer's disease with a presenilin-1 mutation at the site corresponding to the Volga German presenilin-2 mutation.

We describe a new mutation causing Alzheimer's disease (AD) in presenilin-1 (N135D) that is at the homologous site to the presenilin 2 mutation (N141I) in Volga German kindreds. The phenotype of PS1 N135D is an early-onset (34-38 years) disease. The mutation forms part of, and extends, the alpha-helical array of mutations in transmembrane 2 of the presenilins and leads to the suggestion that disruption of this helical face is the molecular insult that leads to disease.

Adult↗
PubMed1996

The 24 kDa proteinases of comoviruses are virus-specific in cis as well as in trans.

To investigate the specificity of comoviral 24 kDa ('24K') proteinases, a full-length cDNA copy of red clover mottle virus (RCMV) RNA 1 has been cloned downstream of a T7 promoter. Translation in rabbit reticulocyte lysates of in vitro transcripts from this clone resulted in the synthesis of a 200K protein which was processed in a manner similar to that of the equivalent protein from cowpea mosaic virus (CPMV). Full-length cDNA clones of the RNA 1 molecules of RCMV and CPMV were used to create hybrid RNA 1 molecules. RNA transcribed in vitro from these hybrids was translated in vitro and the ability of the 24K proteinase from one comovirus to cleave the 32K/170K processing site from the other assessed. The results of the experiments show that the 24K proteinases are virus-specific in cis.

Animals↗
PubMed1993

Expression of an animal virus antigenic site on the surface of a plant virus particle.

To investigate if cowpea mosaic virus (CPMV) particles can be used to express foreign protein sequences, oligonucleotides encoding an epitope derived from VP1 of foot-and-mouth disease virus (FMDV) were cloned into the region of the CPMV genome encoding the small (S) coat protein. The chimeras were designed so that the foreign sequence was expressed either as an insertion or as a replacement for part of the wild-type sequence. While RNA from both chimeras was able to replicate in cowpea protoplasts only the construct containing the FMDV sequence as an insertion was able to direct capsid formation and infect whole cowpea plants. The modified S protein produced in plants infected with the insertion derivative reacted with FMDV-specific antiserum. These results show that CPMV can be used as an antigen presentation system and raises the possibility of producing vaccines in plants using a RNA virus-based vector.

Amino Acid Sequence↗
PubMed1992

Identification and characterization of pseudo-recombinants of red clover mottle comovirus.

cDNA clones specific for the two genomic RNAs of strain O of the comovirus red clover mottle virus (RCMV) were constructed. Using these clones, in conjunction with clones specific for RNAs of RCMV strain S, local lesion isolates containing reciprocal pseudo-recombinants between strains S and O were identified. Investigation of the biological properties of these pseudo-recombinants showed that the ability of RCMV to infect Chenopodium quinoa is determined by B RNA. The results also suggest that both RNAs are involved in symptom formation in Pisum sativum. Analysis of the strain O clones enabled the sequences at the 3' ends of both genomic RNAs of strain O to be determined. Comparison of these sequences with the corresponding region of the strain S RNAs suggests that the 3' terminal sequences critical for replicase recognition may lie somewhat upstream of the poly(A) tract.

Base Sequence↗
PubMed1992

The nucleotide sequence of red clover mottle virus bottom component RNA.

The complete nucleotide sequence of the bottom component RNA (B RNA) of red clover mottle virus strain S has been determined. The sequence consists of 6033 nucleotides and contains a single long open reading frame sufficient to encode a protein of M(r) 210,258. The proteolytic processing sites within this protein have been deduced by comparison of its sequence with that of the B RNA-encoded protein of cowpea mosaic virus. Comparison of the amino acid sequences of the individual proteins confirms that the two viruses have a similar genome organization.

Amino Acid Sequence↗
PubMed1991

Analysis of the nucleotide sequence of bean pod mottle virus middle component RNA.

The complete nucleotide sequence of the middle component RNA (M RNA) of the comovirus bean pod mottle virus (BPMV) has been determined. The sequence consists of 3662 nucleotides and contains a single long open reading frame sufficient to code for a protein of 113,353 Da. The proteolytic processing sites within this protein have been identified by comparison with the known three-dimensional structure of the virion and cleavage at these sites would lead to a range of products consistent with those observed during processing of the M RNA-encoded polyproteins in vitro. We have performed computer-aided searches for reiterated sequences within BPMV M RNA which might explain why ordered RNA is visible in the electron density map of BPMV middle component particles (Chen, Z., Stauffacher, C. V., Li, Y., Schmidt, T., Bomu, W., Kamer, G., Shanks, M., Lomonossoff, G., and Johnson, J. E., 1989, Science 245, 154-159). These searches revealed both the presence of overrepresented pentameric sequences and a consensus sequence which was repeated 15 times within the RNA sequence.

Amino Acid Sequence↗
PubMed1990

The primary structure of the 24K protease from red clover mottle virus: implications for the mode of action of comovirus proteases.

We have determined the nucleotide sequence of the region of red clover mottle virus (RCMV) bottom component RNA which encodes the RCMV equivalent of the cowpea mosaic virus (CPMV) 24K protease. From the alignment of the deduced amino acid sequence of the RCMV 24K protein with that of the homologous protein from CPMV, we speculate on the relative importance of the various amino acid residues which have been implicated in the catalytic mechanism of comovirus proteases.

Amino Acid Sequence↗
PubMed1989

Protein-RNA interactions in an icosahedral virus at 3.0 A resolution.

Nearly 20 percent of the packaged RNA in bean-pod mottle virus (BPMV) binds to the capsid interior in a symmetric fashion and is clearly visible in the electron density map. The RNA displaying icosahedral symmetry is single-stranded with well-defined polarity and stereochemical properties. Interactions with protein are dominated by nonbonding forces with few specific contacts. The tertiary and quaternary structures of the BPMV capsid proteins are similar to those observed in animal picornaviruses, supporting the close relation between plant comoviruses and animal picornaviruses established by previous biological studies.

Amino Acid Sequence↗