Biomedical subjects

Thomas H Roberts

Publications and source records attributed to Thomas H Roberts.

5 recordsLinked to original sources

PubMed2026

Comparative genomics reveals lineage-associated structural variation and diversification in a barley fungal pathogen.

Leaf rust, caused by Puccinia hordei, is a major barley disease worldwide. Despite repeated shifts in virulence, contrasting reproductive histories, and emerging fungicide insensitivity, the genomic basis of its diversification and adaptation remains poorly understood. In this study, we generated haplotype-resolved, chromosome-level genome assemblies for two isolates with contrasting virulence and analyzed 41 Australian isolates collected over 54 yr (1966-2020), integrating comparative and population genomics, mating-type gene phylogenies, chromosome-specific k-mer profiling, genome-wide copy-number variation (CNV) analysis, and gene-expression analysis. We identified a structurally dynamic chromosome characterized by repeat-associated rearrangements, structural variation, and lineage-associated CNV, representing the first evidence in a rust fungus of chromosome-scale structural diversification of this extent. Population analyses distinguished clonally expanded lineages from recombination-associated lineages, with mating-type gene phylogenies providing further support for lineage differentiation. More recently collected isolates showed increased duplication-associated variation, and CNV boundaries were associated with structural-variant breakpoints. We also identified lineage-associated amplification of Cyp51, with increased copy number associated with higher transcript abundance, supporting a potential role in fungicide adaptation. Overall, our findings highlight structural variation, contrasting reproductive histories, and lineage-associated CNV as important contributors to diversification in P. hordei, providing insights for future rust pathogen surveillance and management strategies.

Cyp51 gene↗

PubMed2005

Devastating injuries in healthcare workers: description of the crisis and legislative solution to the epidemic of back injury from patient lifting.

The purpose of this report is to describe a crisis in healthcare, disabling back injuries in US healthcare workers. In addition, outlined is the proven solution of safe, mechanized, patient lifting, which has been shown to prevent these injuries. A "Safe Patient Handling--No Manual Lift" policy must be immediately instituted throughout this country. Such a policy is essential to halt hazardous manual patient lifting, which promotes needless disability and loss of healthcare workers, pain and risk of severe injury to patients, and tremendous waste of financial resources to employers and workers' compensation insurance carriers. Healthcare workers consistently rank among top occupations with disabling back injuries, primarily from manually lifting patients. Back injury may be the single largest contributor to the nursing shortage. Reported injuries to certified nursing assistants are three to four times that of registered nurses. A national healthcare policy for "Safe Patient Handling--No Manual Lift" is urgently needed to address this crisis. Body mechanics training is ineffective in prevention of back injury with patient lifting. Mandated use of mechanical patient lift equipment has proven to prevent most back injury to nursing personnel and reduce pain and injury to patients associated with manual lifting. With the national epidemic of morbid obesity in our country, innovative devices are available for use in emergency medical systems and hospitals for patient lifting and transfer without injury to hospital personnel. The US healthcare industry has not voluntarily taken measures necessary to reduce patient handling injury by use of mechanical lift devices. US healthcare workers who suffer disabling work-related back injuries are limited to the fixed, and often inadequate, relief which they may obtain from workers' compensation. Under workers' compensation law, healthcare workers injured lifting patients may not sue their employer for not providing mechanical lift equipment. Discarding healthcare workers disabled by preventable back injuries is an abuse which legislators must remedy. In addition, Medicare reimbursement policies must also be updated to allow the disabled community to purchase electrically operated overhead ceiling lifts. The US lags far behind countries with legislated manual handling regulations and "No Lifting" nursing policies. England and Australia have had "No Lifting" nursing policies in place since 1996 and 1998, respectively. The National Occupational Research Agenda (NORA) recognized a model in 2003 for reduction of back injuries to nursing staff in US healthcare facilities. Also in 2003, the American Nurses Association called for elimination of manual patient handling because it is unsafe and causes musculoskeletal injuries to nurses. The first state legislation for safe patient handling passed both houses in California but was vetoed by the Governor in September 2004. California and other states are preparing to (re)introduce legislation in January 2005. A national, industry-specific policy is essential to quell the outflow of nursing personnel to disability from manual patient lifting.

Adult↗

PubMed2004

Serpins in unicellular Eukarya, Archaea, and Bacteria: sequence analysis and evolution.

Most serpins irreversibly inactivate specific serine proteinases of the chymotrypsin family. Inhibitory serpins are unusual proteins in that their native structure is metastable, and rapid conversion to a relaxed state is required to trap target enzymes in a covalent complex. The evolutionary origin of the serpin fold is unresolved, and while serpins in animals are known to be involved in the regulation of a remarkable diversity of metabolic processes, the physiological functions of homologues from other phyla are unknown. Addressing these questions, here we analyze serpin genes identified in unicellular eukaryotes: the green alga Chlamydomonas reinhardtii, the dinoflagellate Alexandrium tamarense, and the human pathogens Entamoeba spp., Eimera tenella, Toxoplasma gondii, and Giardia lamblia. We compare these sequences to others, particularly those in the complete genome sequences of Archaea, where serpins were found in only 4 of 13 genera, and Bacteria, in only 9 of 56 genera. The serpins from unicellular organisms appear to be phylogenetically distinct from all of the clades of higher eukaryotic serpins. Most of the sequences from unicellular organisms have the characteristics of inhibitory serpins, and where multiple serpin genes are found in one genome, variability is displayed in the region of the reactive-center loop important for specificity. All the unicellular eukaryotic serpins have large hydrophobic or positively charged residues at the putative PI position. In contrast, none of the prokaryotic serpins has a residue of these types at the predicted P1 position, but many have smaller, neutral residues. Serpin evolution is discussed.

Amino Acid Sequence↗

PubMed2004

Optimised expression and purification of recombinant human indoleamine 2,3-dioxygenase.

The hemoprotein indoleamine 2,3-dioxygenase (IDO) is the first and rate-limiting enzyme in mammalian tryptophan metabolism. It has received considerable attention in recent years, particularly due to its role in the pathogenesis of many diseases. Here, we report attempts to improve soluble expression and purification of hexahistidyl-tagged recombinant human IDO from Escherichia coli (EC538, pREP4, and pQE9-IDO). Significant formation of inclusion bodies was noted at the growth temperature of 37 degrees C, with reduced formation at 30 degrees C. The addition of the natural biosynthetic precursor of protoporphrin IX, delta-aminolevulinic acid (ALA), coupled with optimisation of IPTG induction levels during expression at 30 degrees C and purification by nickel-agarose and size exclusion chromatography, resulted in protein with 1 mol of heme/mol of protein and a specific activity of 160 micromol of kynurenine/h/mg of protein (both identical to native human IDO). The protein was homogeneous in terms of electrophoretic analysis. Yields of soluble protein (3-5 mg/L of bacterial culture) and heme content are greater than previously reported.

Aminolevulinic Acid↗

PubMed2003

Differential gene expression for suicide-substrate serine proteinase inhibitors (serpins) in vegetative and grain tissues of barley.

Proteins of the serpin superfamily (approximately 43 kDa) from mature cereal grains are in vitro suicide-substrate inhibitors of specific mammalian serine proteinases of the chymotrypsin family. However, unlike the 'standard-mechanism' serine proteinase inhibitors (<25 kDa), the biological functions of plant serpins are unknown. Expression studies of genes encoding members of three subfamilies of serpins (BSZx, BSZ4 and BSZ7) in developing grain and vegetative tissues of barley (Hordeum vulgare L.) showed that transcripts encoding BSZx, which inhibits distinct proteinases at overlapping reactive centres in vitro, were ubiquitous at low levels, but the protein could not be detected. EST analysis showed that expression of genes for serpins with BSZx-type reactive centres in vegetative tissues is widespread in the plant kingdom, suggesting a common regulatory function. For BSZ4 and BSZ7, expression at the protein level was highest in the maturing grain (> or d post-anthesis), where these serpins were localized by immunomicroscopy to the central and peripheral starchy endosperm, subaleurone, and (at lower levels) to the aleurone. Serpins were also localized to the meristem and vascular tissues of roots, and to the phloem of coleoptiles and leaves. The identification of BSZ4 in vegetative tissues by western blotting was confirmed for the roots by purification and amino acid sequencing, and for the leaves by in vitro reactive-centre loop cleavage studies. Plant serpins are likely to use their irreversible inhibitory mechanism in the inhibition of exogenous proteinases capable of breaking down seed storage proteins, and in the defence of specific cell types in vegetative tissues.

Blotting, Western↗