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Biomedical subjects

Richard Harris

Publications and source records attributed to Richard Harris.

10 recordsLinked to original sources
PubMed2026

A single-case foodborne botulism outbreak caused by Clostridium botulinum type A1(B5) in diced garlic in Newfoundland and Labrador, 2024.

Foodborne botulism is a severe neuroparalytic disease caused by ingestion of foods containing botulinum neurotoxins, produced by Clostridium botulinum. In 2024, a 74-year-old woman from Newfoundland and Labrador with complete bilateral flaccid paralysis and respiratory distress was hospitalized and required intubation. From the broader differential diagnosis list, botulism was favoured prior to laboratory confirmation. Serum and feces samples initially tested negative for botulinum neurotoxins by mouse bioassay, yet viable C. botulinum type A was recovered from the feces. Food history investigation included some diced garlic in a repurposed coffee container that tested negative for botulinum neurotoxins by mouse bioassay, but viable C. botulinum type A was recovered from the sample. Both the fecal and garlic enrichment cultures were positive for bont/A and bont/B genes by real-time PCR. Whole genome sequencing revealed that both fecal and garlic isolates were highly similar with conserved gene synteny, including an intact bont/A1 gene and a disrupted (silent) bont/B5 gene encoded on the chromosome. This single-case foodborne botulism outbreak from Newfoundland and Labrador in 2024 was caused by C. botulinum type A1(B5) in diced garlic.

Aged↗
PubMed2003

Waterborne outbreak of gastroenteritis associated with a norovirus.

The Wyoming Department of Health investigated an outbreak of acute gastroenteritis among persons who dined at a tourist saloon in central Wyoming during October 2001. Human caliciviruses (HuCVs) were suspected as the etiological agent of the outbreak based on the incubation period, duration of illness, and symptoms observed in ill patrons. A retrospective cohort study demonstrated that ill patrons were 4.5 times more likely to have exposure to drinking water and/or ice than nonill patrons. No food items were associated with illness. An environmental investigation gave evidence that the saloon's groundwater was contaminated with sewage. Water from the saloon's only well was processed for viruses. The processed water sample and stool samples collected from three ill patrons were analyzed by reverse transcription-PCR (RT-PCR) for the presence of HuCV. All positive RT-PCR results were confirmed by sequence and phylogenetic analyses of cloned RT-PCR products. A genogroup I, subtype 3, HuCV stain was found to be present in the well water sample and two stool samples. In addition, a genogroup II, subtype 6, strain was detected in one stool sample. The identification of the same HuCV strain in both the well water and stool samples strongly suggests a link between exposure to well water and the outbreak of gastroenteritis. The presence of a genogroup II, subtype 6, strain in one of the stool samples suggests that multiple HuCV strains may have been involved in this outbreak. The laboratory isolation of HuCV strains from outbreak-associated drinking water is relatively novel in the United States. This investigation outlines the procedure for virus isolation and illustrates the utility of RT-PCR for the identification of HuCV in large volumes of water and stool samples obtained during outbreaks of acute nonbacterial gastroenteritis.

Base Sequence↗
PubMed2002

H-NS oligomerization domain structure reveals the mechanism for high order self-association of the intact protein.

H-NS plays a role in condensing DNA in the bacterial nucleoid. This 136 amino acid protein comprises two functional domains separated by a flexible linker. High order structures formed by the N-terminal oligomerization domain (residues 1-89) constitute the basis of a protein scaffold that binds DNA via the C-terminal domain. Deletion of residues 57-89 or 64-89 of the oligomerization domain precludes high order structure formation, yielding a discrete dimer. This dimerization event represents the initial event in the formation of high order structure. The dimers thus constitute the basic building block of the protein scaffold. The three-dimensional solution structure of one of these units (residues 1-57) has been determined. Activity of these structural units is demonstrated by a dominant negative effect on high order structure formation on addition to the full length protein. Truncated and site-directed mutant forms of the N-terminal domain of H-NS reveal how the dimeric unit self-associates in a head-to-tail manner and demonstrate the importance of secondary structure in this interaction to form high order structures. A model is presented for the structural basis for DNA packaging in bacterial cells.

Amino Acid Sequence↗
PubMed2002

Tenidap, a novel anti-inflammatory agent, is an opener of the inwardly rectifying K+ channel hKir2.3.

We studied the effect of a novel anti-inflammatory agent, tenidap, on a cloned inwardly rectifying K+ channel, hKir2.3. Tenidap (a) potently potentiated 86Rb+ efflux through hKir2.3 channels expressed in Chinese hamster ovary cells (EC50=402 nM), (b) reversibly and dose-dependently increased whole-cell and macro-patch hKir2.3 currents (maximum whole-cell current response to tenidap was 230+/-27% of control; EC50=1.3 microM.), and (c) caused dose-dependent and Ba2+-sensitive membrane hyperpolarizations and concurrent decreases in input resistance. Potentiation of hKir2.3 by tenidap was unaffected by inhibitors of phospholipase A2, protein kinase C, or arachidonic acid metabolic pathways. The action of tenidap was not intracellular. Tenidap also had little or no effect on currents flowing through hKir2.1, Kv1.5, and micro1 Na+ channels. Our results demonstrate that tenidap is a potent opener of hKir2.3 and suggest that it can serve as a valuable pharmacological tool for studying physiological and pathological processes involving Kir2.3.

Animals↗
PubMed2002

Chaperonin assisted overexpression, purification, and characterisation of human PP2A methyltransferase.

Protein phosphatase 2A (PP2A) is a ubiquitous phosphatase found in many eukaryotic cell types and is involved in regulating a number of intracellular signalling pathways. Its activity, in turn, is regulated through covalent modification, involving phosphorylation and methylation reactions. The effect of phosphorylation on the activity of the protein is well known, but the effects of methylation have only recently been documented and the mechanistic details of methylation are lacking. Methylation, which occurs on the catalytic subunit of PP2A, is catalysed by PP2A methyltransferase (PP2Amt). Here, we present a method for the large-scale purification of human PP2Amt using an Escherichia coli host, coexpressing the chaperonins GroEL and GroES. Purified PP2Amt was identified by peptide mass mapping using MALD-MS and peptide sequencing using ESI-LC-MS/MS. The CD spectrum indicated that purified PP2Amt was folded, with about one-third of the protein adopting an alpha-helical conformation. Analytical gel filtration estimated the molecular weight to be 34kDa, equivalent to the monomeric form of the protein. Further CD analysis showed that in the presence and absence of the ligand S-adenosylhomocysteine, the thermal denaturation profiles were biphasic. However, the transition midpoints shifted to a higher temperature in the presence of ligand, indicating stabilisation of ligand-bound PP2Amt compared to the apo-form. We also report on the progress made in determining the structure of PP2Amt, using both X-ray crystallography and NMR spectroscopy.

Base Sequence↗
PubMed2001

The X-ray crystal structure and putative ligand-derived peptide binding properties of gamma-aminobutyric acid receptor type A receptor-associated protein.

The gamma-aminobutyric acid receptor type A (GABA(A)) receptor-associated protein (GABARAP) has been reported to mediate the interaction between the GABA(A) receptor and microtubules. We present the three-dimensional structure of GABARAP obtained by x-ray diffraction at 1.75 A resolution. The structure was determined by molecular replacement using the structure of the homologous protein GATE-16. NMR spectroscopy of isotope-labeled GABARAP showed the structure in solution to be compatible with the overall fold but showed evidence of conformation heterogeneity that is not apparent in the crystal structure. We assessed the binding of GABARAP to peptides derived from reported binding partner proteins, including the M3-M4 loop of the gamma2 subunit of the GABA(A) receptor and the acidic carboxyl-terminal tails of human alpha- and beta-tubulin. There is a small area of concentrated positive charge on one surface of GABARAP, which we found interacts weakly with all peptides tested, but we found no evidence for specific binding to the proposed physiological target peptides. These results are compatible with a more general role in membrane targeting and transportation for the GABARAP family of proteins.

Adaptor Proteins, Signal Transducing↗