Biomedical subjects

Michael D Jones

Publications and source records attributed to Michael D Jones.

6 recordsLinked to original sources

PubMed2006

The application of sub-2-microm particle liquid chromatography-operated high mobile linear velocities coupled to orthogonal accelerated time-of-flight mass spectrometry for the analysis of ranitidine and its impurities.

Impurity profiling of pharmaceutical drug substances or dosage formulations require methods involving high sensitivity and resolution from LC and MS alike as well as an acceptable analysis time. While throughput can be increased, it is usually at the expense of chromatographic resolution. The application of sub-2-microm stationary phases and high mobile linear velocities has been combined with orthogonal acceleration (oa)-TOF MS for the impurity structural characterization analysis of small-molecule pharmaceutics. A pharmaceutical drug substance was forcefully degraded and used to test the proof of concept of developing an impurity profile method by ultra performance liquid chromatography (UPLC). Optimum conditions were identified by use of method development simulation software as well as traditional approaches of method scouting with columns and a varied range of pH. Further analysis illustrated the effectiveness of applying oa-TOF MS techniques to assist in achieving exact mass coupled with MS/MS to define the structural characterization of the related substances relative to the pharmaceutical active ingredient and identification of any unknown impurity substances. The barriers with trade-offs between resolution and speed are overcome by the application of UPLC, whereas the increased sensitivity provides for superior exact mass oa-TOF MS.

Chemistry Techniques, Analytical↗

PubMed2005

Candida glabrata Ste11 is involved in adaptation to hypertonic stress, maintenance of wild-type levels of filamentation and plays a role in virulence.

The conserved family of fungal Ste11 mitogen activated protein kinase/kinases play important roles in several signalling cascades. We have cloned the STE11 homologue from the fungal pathogen Candida glabrata. The C. glabrata gene is present in a single copy in the genome, contains a well-conserved catalytic domain typical of the serine-threonine protein kinases and a sterile alpha motif widespread in signalling and nuclear proteins. Hypothetical translation of C. glabrata STE11 suggests that the protein has 64% identity and 77% similarity at the amino acid level to Saccharomyces cerevisiae Ste11. We have shown that C. glabrata STE11 can complement the mating defect and partially rescue the reduced nitrogen starvation induced filamentation of S. cerevisiae ste11 mutants. Functional analysis of a C. glabrata ste11 null mutant demonstrates that Ste11 is required for adaptation to hypertonic stress but is largely dispensable for maintenance of cell wall integrity. It also plays a role in C. glabrata nitrogen starvation induced filamentation. Survival analysis revealed that C. glabrata ste11 mutants, while still able to cause disease, are attenuated for virulence compared to reconstituted, STE11 cells. These data suggest that C. glabrata Ste11, in a similar fashion to the S. cerevisiae protein, functions in a number of different signalling modules.

Amino Acid Sequence↗

PubMed2005

Pinch-an-inch test for appendicitis.

Rebound tenderness is a widely used examination technique for patients with suspected appendicitis, but it can be quite uncomfortable. An alternative test for peritonitis is termed the "pinch-an-inch" test. This report describes two patients who presented with mild abdominal pain who subsequently were found to have appendicitis. In both patients, classic peritoneal signs were absent, but the pinch-an-inch test was positive. The experienced physician's bedside clinical examination remains the most critical component for rapidly identifying peritonitis. Although rebound tenderness is a widely used examination, it is uncomfortable and may be inaccurate. To perform the pinch-an-inch test, a fold of abdominal skin over McBurney's point is grasped and elevated away from the peritoneum. The skin is allowed to recoil back briskly against the peritoneum. If the patient has increased pain when the skin fold strikes the peritoneum, the test is positive and peritonitis probably is present.

Adult↗

PubMed2004

Use of mass spectrometry to identify protein biomarkers of disease severity in the synovial fluid and serum of patients with rheumatoid arthritis.

OBJECTIVE: To identify a panel of candidate protein biomarkers of rheumatoid arthritis (RA) that can predict which patients will develop erosive, disabling disease. METHODS: A 2-step proteomic approach was used for biomarker discovery and verification. In the first step, 2-dimensional liquid chromatography-coupled tandem mass spectrometry was used to generate protein profiles of synovial fluid (SF) from patients with either erosive RA (n = 5) or nonerosive RA (n = 5). In the second step, the selected candidate markers were verified using quantitative multiple reaction monitoring mass spectrometry in sera of patients with erosive RA (n = 15) or nonerosive RA (n = 15) and of healthy controls (n = 15). RESULTS: Through differential profiling of proteins in the <40-kd portion of the SF proteome, we selected 33 prospective candidate biomarkers from a total of 418 identified proteins. Among the proteins that were elevated in the SF of patients with erosive RA were C-reactive protein (CRP) and 6 members of the S100 protein family of calcium-binding proteins. Significantly, levels of CRP, S100A8 (calgranulin A), S100A9 (calgranulin B), and S100A12 (calgranulin C) proteins were also elevated in the serum of patients with erosive disease compared with patients with nonerosive RA or healthy individuals. CONCLUSION: Several potential protein marker candidates have been identified for prognosis of the erosive form of RA. This study demonstrates the facility of using protein mass spectrometry in SF and serum for global discovery and verification of clinically relevant sets of disease biomarkers.

Adult↗

PubMed2004

Inactivation of transcription factor gene ACE2 in the fungal pathogen Candida glabrata results in hypervirulence.

During an infection, the coordinated orchestration of many factors by the invading organism is required for disease to be initiated and to progress. The elucidation of the processes involved is critical to the development of a clear understanding of host-pathogen interactions. For Candida species, the inactivation of many fungal attributes has been shown to result in attenuation. Here we demonstrate that the Candida glabrata homolog of the Saccharomyces cerevisiae transcription factor gene ACE2 encodes a function that mediates virulence in a novel way. Inactivation of C. glabrata ACE2 does not result in attenuation but, conversely, in a strain that is hypervirulent in a murine model of invasive candidiasis. C. glabrata ace2 null mutants cause systemic infections characterized by fungal escape from the vasculature, tissue penetration, proliferation in vivo, and considerable overstimulation of the proinflammatory arm of the innate immune response. Compared to the case with wild-type fungi, mortality occurs much earlier in mice infected with C. glabrata ace2 cells, and furthermore, 200-fold lower doses are required to induce uniformly fatal infections. These data demonstrate that C. glabrata ACE2 encodes a function that plays a critical role in mediating the host-Candida interaction. It is the first virulence-moderating gene to be described for a Candida species.

Alleles↗

PubMed2003

Candida glabrata STE12 is required for wild-type levels of virulence and nitrogen starvation induced filamentation.

The highly conserved fungal Ste12 transcription factor family of proteins play critical roles in the regulation of many cellular processes including mating, cell wall biosynthesis, filamentation and invasive growth. They are also important mediators of fungal virulence. The Candida glabrata STE12 homologue was cloned. The encoded protein has a single DNA binding homeodomain but lacks both a C2H2 zinc finger DNA binding domain and an apparent Dig1/Dig2 regulatory motif. Candida glabrata STE12 can functionally complement the nitrogen starvation induced filamentation and mating defects of Saccharomyces cerevisiae ste12 mutants. We also show that C. glabrata STE12 is required for nitrogen starvation-induced filamentation as ste12 mutants rarely produce pseudohyphae on nitrogen depleted media. Finally we describe a novel murine model of C. glabrata systemic disease and use this to demonstrate that C. glabrata ste12 mutants, although still able to cause disease, are attenuated for virulence compared with STE12 reconstituted strains. Candida glabrata STE12 is therefore the first virulence factor encoding gene to be described in this increasingly important fungal pathogen.

Animals↗