Factors associated with Giardia infection in dogs in southern Ontario, Canada

Information concerning risk factors associated with Giardia infection in dogs in southern Ontario, Canada, is currently lacking. This study therefore aimed to identify risk factors for Giardia infection in dogs that visit off-leash dog parks in southern Ontario. From May-November 2018, fecal samples were collected from 466 dogs in 12 off-leash dog parks in the Niagara and Hamilton regions of Ontario. A survey that asked questions pertaining to travel history (i.e., area of residence, locations and regions visited in the previous 6 months), basic medical history (i.e., spay/neuter status, veterinary visits, use of deworming medication), consumption of a raw diet, and the physical (i.e., age, sex, breed) and behavioral characteristics (i.e., off-leash activities, hunting activities) of each dog sampled was administered to the respective owner. All fecal samples were examined with the Giardia plate ELISA (IDEXX Laboratories) for parasite antigen. Multivariable logistic regression analyses were conducted on the survey data to investigate putative risk factors for Giardia infection. Overall, 11.8% (95% CI: 9.2-15.1%) of samples tested positive for Giardia antigen. Results from the multivariable logistic regression analyses identified an interaction between dog age and spay/neuter status that was significantly associated with Giardia infection. The odds of infection were greater in intact as compared to neutered adult dogs (OR: 3.6, 95% CI: 1.7-7.9, p = 0.001), and in neutered juvenile dogs as compared to neutered adults (OR: 5.2, 95% CI: 2.2-12.2, p < 0.001). The results provide veterinarians with evidence-based information for identifying dogs at greatest risk of Giardia infection in southern Ontario.

Maximizing hydrophobic peptide recovery in proteomics and antibody development using a mass spectrometry compatible surfactant

Peptide loss due to surface absorption can happen at any step in a protein analysis workflow and is sometimes especially deleterious for hydrophobic peptides. In this study, we found the LC-MS compatible surfactant, n-Dodecyl-β-D-maltoside (DDM), can maximize hydrophobic peptide recovery in various samples including single cell digests, mAb clinical PK samples, and mAb peptide mapping samples. In HeLa single cell proteomics analysis, more than half of all unique peptides identified were found only in DDM prepared samples, most of which had significantly higher hydrophobicities compared to peptides in control samples. In clinical PK studies, DDM enhanced hydrophobic complementarity-determining region (CDR) peptide signals significantly. The fold change of CDR peptides' intensity enhancement in DDM added samples compared to controls correlate with peptide retention time and hydrophobicity, providing guidance for surrogate peptide selection and peptide standard handling in PK studies. For peptide mapping analysis of mAbs, DDM can improve hydrophobic peptide signal and solution stability over 48 h in an autosampler at 4 °C, which can aid method qualification and transfer during drug development. Lastly, maximizing hydrophobic peptide recovery from samples dried in vacuo was achieved by DDM reconstitution, which provided higher signal for later eluting peaks and higher proteome coverage overall.

Development of a simple non-reduced peptide mapping method that prevents disulfide scrambling of mAbs without affecting tryptic enzyme activity

Non-reduced peptide mapping by liquid chromatography-mass spectrometry (LC-MS) analysis is a commonly used method for disulfide linkage characterization to assess structural integrity and quality of therapeutic monoclonal antibodies (mAbs). However, disulfide scrambling artifacts induced during sample preparation are often observed when basic pH and high temperatures are used during denaturation and digestion. To minimize disulfide scrambling artifacts, methods using various acidic pH conditions have been developed by multiple groups. However, lower pH conditions increase missed and non-specific cleavages, which complicates disulfide bond analysis because the majority of enzymes used in protein characterization are most efficient at alkaline pH. Here, we developed a non-reduced peptide mapping method for mAb characterization that minimizes disulfide scrambling at basic pH by adding an oxidizing agent, cystamine, and a low concentration of iodoacetamide (IAA) alkylating agent. Two human IgG1 mAbs, one with kappa light chain and another one with lambda light chain, were used as model proteins to develop and optimize the method. Using this novel method, disulfide scrambled peptides related to light chain-heavy chain (LC-HC) inter-disulfide disruption were significantly reduced with high reproducibility compared to conventional methods. Results demonstrated that the cystamine-added method is robust and minimizes disulfide scrambling artifacts produced during sample preparation.

Prevalence of intestinal parasites in dogs in southern Ontario, Canada, based on fecal samples tested using sucrose double centrifugation and Fecal Dx® tests

In southern Ontario, Canada, there is a lack of information concerning the prevalence of intestinal parasites in dogs. As such, this study aimed to characterize the prevalence of intestinal parasites in dogs visiting off-leash parks in the region using sucrose double centrifugation and Fecal Dx® tests. Additionally, data obtained via the sucrose double centrifugation method were used to evaluate the performance of the Fecal Dx® tests. Fecal samples were collected from 466 dogs aged ≥6 months from May to November 2018 (mean age = 3.7 years). Overall, eleven intestinal parasites were identified using sucrose double centrifugation. Roundworm eggs (Toxocara canis and Baylisascaris procyonis), hookworm eggs (Ancylostoma caninum and Uncinaria stenocephala), and whipworm eggs (Trichuris vulpis) were identified in 1.07% (95% confidence interval [CI] 0.38-2.56%), 5.79% (95% CI 3.85-8.31%), and 5.15% (95% CI 3.33-7.57) of samples, respectively. Using the Fecal Dx® tests, 1.07% (95% CI 0.38-2.56%), 4.29% (95% CI 2.64-6.55%), and 2.15% (95% CI 1.03-3.91) of the samples tested positive for roundworm, hookworm, and whipworm antigen, respectively. To assess the level of agreement between the Fecal Dx® tests and sucrose double centrifugation, three methods were used. Cohen's kappa indicated a fair-to-moderate level of agreement between Fecal Dx® tests and sucrose double centrifugation. In contrast, the prevalence-adjusted bias-adjusted kappa and Gwet's first-order agreement coefficient indicated almost perfect agreement between these tests, ranging from 0.87 to 0.99 among the parasites examined. This study provides valuable information on the prevalence of intestinal parasites in mature dogs in southern Ontario that will help guide parasite control recommendations for dogs in this region.

Giant Red Kidney Worm (Dioctophyma renale) Screening and Treatment Protocol and Aberrant Worm Migration In Dogs From Ontario and Manitoba, Canada

The life cycle of Dioctophyma renale involves an intermediate host (oligochaete), a paratenic hosts (fish and frogs), and a definitive host (mustelids and canids). Dogs are at risk of infection with D. renale when they consume paratenic hosts infected with the larval form of D. renale. Water containing the oligochaete intermediate host cannot be disregarded as another source of infection. Infections occur mainly in the right kidney, but worms have also been found in the abdominal cavity as well as other organs. Most dogs appear asymptomatic and infections are usually noted as incidental findings on necropsy. Recently, the Ontario Society for the Prevention of Cruelty to Animals (SPCA) and Humane Society conducted transports of dogs located in northern remote communities. In 2016, some female dogs were found to be infected with D. renale upon ovariohysterectomy. In response to this discovery, we developed a screening protocol to screen for D. renale infections. In 2018, a total of 130 intact dogs were transferred from 2 northern communities in the provinces of Ontario and Manitoba. A prevalence of 7.94% (95% confidence interval 3.87-14.11%) was found from dogs from the northern communities. The screening protocol we developed provides a method of screening for dogs that are transported from communities that could be at risk of infection with D. renale.

Simple and Sensitive Method for Deep Profiling of Host Cell Proteins in Therapeutic Antibodies by Combining Ultra-Low Trypsin Concentration Digestion, Long Chromatographic Gradients, and BoxCar Mass Spectrometry Acquisition

Liquid chromatography coupled to mass spectrometry (LC-MS) is a powerful tool for the analysis of host cell proteins (HCP) during antibody drug process development due to its sensitivity, selectivity, and adaptability. However, the enormous dynamic range between the therapeutic antibody and accompanying HCPs poses a significant challenge for LC-MS based detection of these low abundance impurities. To address this challenge, enrichment of HCPs via immunoaffinity, protein A, 2D-LC, or other strategies is typically performed. However, these enrichments are time-consuming and sometimes require a large quantity of sample. Here, we report a simple and sensitive strategy to analyze HCPs in therapeutic antibody samples without cumbersome enrichment by combining an ultra-low trypsin concentration during digestion under nondenaturing conditions, a long chromatographic gradient, and BoxCar acquisition (ULTLB) on a quadrupole-Orbitrap mass spectrometer. Application of this strategy to the NIST monoclonal antibody standard (NISTmAb) resulted in the identification of 453 mouse HCPs, which is a significant increase in the number of identified HCPs without enrichment compared to previous reports. Known amounts of HCPs were spiked into the purified antibody drug substance, demonstrating that the method sensitivity is as low as 0.5 ppm. Thus, the ULTLB method represents a sensitive and simple platform for deep profiling of HCPs in antibodies.

Electron Transfer Dissociation Parameter Optimization Using Design of Experiments Increases Sequence Coverage of Monoclonal Antibodies

Middle-down analysis of monoclonal antibodies (mAbs) by tandem mass spectrometry (MS²) can provide detailed insight into their primary structure with minimal sample preparation. The middle-down approach uses an enzyme to cleave mAbs into Fc/2, LC, and Fd subunits that are then analyzed by reversed phase liquid chromatography tandem mass spectrometry (RPLC-MS²). As maximum sequence coverage is desired to obtain meaningful structural information at the subunit level, a host of dissociation methods have been developed, and sometimes combined, to bolster fragmentation and increase the number of identified fragments. Here, we present a design of experiments (DOE) approach to optimize MS² parameters, in particular those that may influence electron transfer dissociation (ETD) efficiency to increase the sequence coverage of antibody subunits. Applying this approach to the NIST monoclonal antibody standard (NISTmAb) using three RPLC-MS² runs resulted in high sequence coverages of 67%, 67%, and 52% for Fc/2, LC, and Fd subunits, respectively. In addition, we apply this DOE strategy to model the parameters required to maximize the number of fragments produced in "low", "medium", and "high" mass ranges, which ultimately resulted in even higher sequence coverages of NISTmAb subunits (75%, 78%, and 64% for Fc/2, LC, and Fd subunits, respectively). The DOE approach provides high sequence coverage percentages utilizing only one fragmentation method, ETD, and could be extended to other state-of-the-art techniques that combine multiple fragmentation mechanisms to increase coverage.

Integration of liquid chromatography mass spectrometry with a heavy peptide response curve accurately measures unprocessed C-terminal lysine during peptide mapping analysis of therapeutic antibodies in a single run

Therapeutic monoclonal and bispecific antibodies are susceptible to modification after protein biosynthesis. These post-translational modifications (PTMs) not only contribute to mass and charge heterogeneity, but they can also negatively impact the molecule's activity, half-life, and immunogenicity. Therefore, identification and quantification of PTMs are critical to ensure the safety and efficacy of an antibody therapeutic as well as demonstrate product consistency and process control. Unprocessed C-terminal lysine on the heavy chain (HC) is a prevalent modification that contributes to this charge heterogeneity in antibodies. Peptide mapping through liquid chromatography tandem mass spectrometry (LC-MS²) enjoys higher selectivity and sensitivity for measuring this PTM relative to global PTM methods, but differences in the ionization efficiencies of the unprocessed C-terminal K peptide and the truncated C-terminal K peptide result in its overestimation. Consequently, large discrepancies in this PTM's measured abundance may exist between different characterization assays used in regulatory filings, which can be further compounded by large variability when multiple mass spectrometers are used to quantify C-terminal K during a therapeutic's lifespan. In this study, we propose a simple new method to quantify unprocessed C-terminal K in antibodies in a single LC-MS² run that incorporates heavy isotopic standards for both the unprocessed and truncated C-terminal K peptide to build a response curve and correct for the disparity in ionization efficiency between these two different peptide sequences. The approach was evaluated across two different Orbitrap-based mass spectrometers using multiple monoclonal and bispecific therapeutic antibodies, resulting in accurate (<10% error, as determined with peptide standards) and precise C-terminal K quantification during peptide mapping analysis.

Evaluation of the prevalence of Echinococcus multilocularis in dogs that visit off-leash dog parks in southern Ontario, Canada

Prior to 2012, Echinococcus multilocularis was not known to occur in any host in Ontario, Canada. However, since that year, five cases of alveolar echinococcosis have been diagnosed in dogs that resided at the western end of Lake Ontario. In addition, E. multilocularis has been shown to be a common infection in wild canids (i.e. coyotes and foxes) across southern Ontario with a high-risk infection cluster in the area surrounding the western shores of Lake Ontario and northern shores of Lake Erie. In regions endemic for E. multilocularis, dog ownership is considered a risk factor for human alveolar echinococcosis. A study was therefore carried out to determine the prevalence of E. multilocularis intestinal infections in dogs within the high-risk infection cluster. From May to November 2018, faecal samples were collected from 477 dogs aged ≥6 months that visited 12 off-leash dog parks in the Halton, Hamilton and Niagara public health units. Faecal samples were analysed via a magnetic capture probe DNA extraction and real-time PCR method for E. multilocularis DNA. Overall, 0% (97.5% CI: 0%-0.80%) of samples tested positive. This result informs preventive recommendations for E. multilocularis infections in dogs in this region.

Quantitative proteomic analysis of a genetically induced prostate inflammation mouse model via custom 4-plex DiLeu isobaric labeling

Inflammation is involved in many prostate pathologies including infection, benign prostatic hyperplasia, and prostate cancer. Preclinical models are critical to our understanding of disease mechanisms, yet few models are genetically tractable. Here, we present a comparative quantitative proteomic analysis of urine from mice with and without prostate-specific inflammation induced by conditional prostate epithelial IL-1β expression. Relative quantification and sample multiplexing was achieved using custom 4-plex N,N-dimethyl leucine (DiLeu) isobaric tags and nanoflow ultrahigh-performance liquid chromatography coupled to high-resolution tandem mass spectrometry. Each set of 4-plex DiLeu reagents allows four urine samples to be analyzed simultaneously, providing high-throughput and accurate quantification of urinary proteins. Proteins involved in the acute phase response, including haptoglobin, inter-α-trypsin inhibitor, and α1-antitrypsin 1-1, were differentially represented in the urine of mice with prostate inflammation. Mass spectrometry-based quantitative urinary proteomics represents a promising bioanalytical strategy for biomarker discovery and the elucidation of molecular mechanisms in urological research.

Evaluation and Application of Dimethylated Amino Acids as Isobaric Tags for Quantitative Proteomics of the TGF-β/Smad3 Signaling Pathway

Isobaric labeling has become a widespread tool for quantitative proteomic studies. Here, we report the development and evaluation of several dimethylated amino acids as novel isobaric tags for quantitative proteomics. Four-plex dimethylated alanine (DiAla), valine (DiVal), and leucine (DiLeu) have been synthesized, sharing common features of peptide tagging and reporter ion production. DiAla and DiLeu are shown to achieve complete labeling. These two tags' impacts on peptide fragmentation and quantitation are further evaluated using HEK293 cell lysate. DiAla labeling generates more abundant backbone fragmentation whereas DiLeu labeling produces more intense reporter ions. Nonetheless, both tags enable accurate quantitative analysis of HEK293 cell proteomes. DiAla and DiLeu tags are then applied to study the TGF-β/Smad3 pathway with four differentially treated mouse vascular smooth muscle (MOVAS) cells. Our MS data reveal proteome-wide changes of AdSmad3 as compared to the GFP control, consistent with previous findings of causing smooth muscle cell (SMC) dedifferentiation.1 Additionally, the other two novel mutations on the hub protein Smad3, Y226A, and D408H, show compromised TGF-β/Smad3-dependent gene transcription and reversed phenotypic switch. These results are further corroborated with Western blotting and demonstrate that the novel DiAla and DiLeu isobaric tagging reagents provide useful tools for multiplex quantitative proteomics.

In-Depth Characterization and Validation of Human Urine Metabolomes Reveal Novel Metabolic Signatures of Lower Urinary Tract Symptoms

Lower urinary tract symptoms (LUTS) are a range of irritative or obstructive symptoms that commonly afflict aging population. The diagnosis is mostly based on patient-reported symptoms, and current medication often fails to completely eliminate these symptoms. There is a pressing need for objective non-invasive approaches to measure symptoms and understand disease mechanisms. We developed an in-depth workflow combining urine metabolomics analysis and machine learning bioinformatics to characterize metabolic alterations and support objective diagnosis of LUTS. Machine learning feature selection and statistical tests were combined to identify candidate biomarkers, which were statistically validated with leave-one-patient-out cross-validation and absolutely quantified by selected reaction monitoring assay. Receiver operating characteristic analysis showed highly-accurate prediction power of candidate biomarkers to stratify patients into disease or non-diseased categories. The key metabolites and pathways may be possibly correlated with smooth muscle tone changes, increased collagen content, and inflammation, which have been identified as potential contributors to urinary dysfunction in humans and rodents. Periurethral tissue staining revealed a significant increase in collagen content and tissue stiffness in men with LUTS. Together, our study provides the first characterization and validation of LUTS urinary metabolites and pathways to support the future development of a urine-based diagnostic test for LUTS.

Ten years of experience with intravesical and intrasphincteric onabotulinumtoxinA in children

OBJECTIVE

To review 10 years of experience with both intravesical and intrasphincteric onabotulinumtoxinA (Botox(®)) injections in children.

PATIENTS AND METHODS

Fifty three children aged between 1 and 18 years at first injection had a combined total of 134 injections (106 intravesical, 23 intrasphincteric and five combined) between January 2004 and December 2013 at Princess Margaret Hospital. Follow-up occurred 3 months post procedure, and then 3-6 monthly. Response to Botox was graded according to the International Children's Continence Society (ICCS) response to treatment scale. Response time was the time that the injection remained effective before symptoms relapsed to the ICCS 'no response' category Nevéus et al., 2006.

RESULTS

Median response times to Botox by pathology are summarised in Table 1. For detrusor overactivity (DO), the response after each Botox injection was in the ICCS '>90% symptom reduction' category Nevéus et al., 2006. Two children had sustained responses to Botox for a tenth and eleventh injection, respectively. A total of 45% of children receiving intrasphincteric Botox for chronic dysfunctional voiding (DV) or detrusor sphincter dyssynergia (DSD) had no symptom recurrence. Intravesical Botox was effective for treating new-onset hydronephrosis secondary to neurogenic bladder in one child. Intravesical Botox had a sustained effect over five injections in eliminating trigonal hypersensitivity and pain with CIC in one child. Episodes of severe autonomic dysreflexia in one child with a high cord transection were effectively eliminated by intravesical Botox, and were sustained over three injections. Thirteen of the 134 Botox injections (9.7%) had a symptomatic culture-positive urinary tract infection (UTI) in the 2 weeks following injection. All had a history of previous UTI. Three children (2.8%) developed urinary retention after intravesical injection.

DISCUSSION

Intravesical Botox remained effective after up to eleven injections. In children with DV or DSD, the response to Botox was more variable, but 45% experienced symptom resolution with no recurrence. Trigonal hypersensitivity with CIC improved in a child after Botox. Botox may confer long-term bladder and upper tract protection in the neurogenic patient group. Severe episodes of autonomic dysreflexia triggered by bladder fill in a child with high cord lesion were eliminated by intravesical Botox.

CONCLUSION

This study demonstrated that intravesical Botox remained effective in response quality and response time in children up to an eleventh injection. This is one of the longer follow-up studies in children published to date. Botox was effective in numbing trigonal hypersensitivity, treating new-onset hydronephrosis secondary to neurogenic bladder, and eliminating episodes of autonomic dysreflexia in one patient each.

Isotopic N,N-Dimethyl Leucine (iDiLeu) for Absolute Quantification of Peptides Using a Standard Curve Approach

Quantitative proteomics studies require an absolute quantification step to accurately measure changes in protein concentration. Absolute quantification using liquid chromatography-mass spectrometry (LC-MS) traditionally combines triple quadrupole instrumentation with stable isotope-labeled standards to measure protein concentrations via their enzymatically produced peptides. Chemical modification of peptides using labels like mass differential tags for relative and absolute quantification (mTRAQ) provides another route to determine protein quantities. This chapter describes a cost-effective and high-throughput chemical labeling method that utilizes five amine-reactive, isotopic N,N-dimethyl leucine (iDiLeu) reagents. These tags enable generation of four-point calibration curves in one LC-MS run to determine protein concentrations from labeled peptides. In particular, we provide a detailed workflow for protein quantification using the iDiLeu reagent that includes important considerations like labeling conditions and isotopic interference correction.

Relative quantification of amine-containing metabolites using isobaric N,N-dimethyl leucine (DiLeu) reagents via LC-ESI-MS/MS and CE-ESI-MS/MS

Tandem mass spectrometry (MS/MS)-based relative quantification by isobaric labeling is a useful technique to compare different metabolic expression levels in biological systems. For the first time, we have labeled primary and secondary amine-containing small molecules using 4-plex isobaric N,N-dimethyl leucine (DiLeu) to perform relative quantification. Good labeling efficiency and quantification accuracy were demonstrated with a mixture of 12 metabolite standards including amino acids and small molecule neurotransmitters. Labeling amine-containing metabolites with DiLeu reagents also enabled the separation of polar metabolites by nanoRPLC and improved the detection sensitivity by CE-ESI-MS. The 4-plex DiLeu labeling technique combined with LC-MS/MS and CE-MS/MS platforms were applied to profile and quantify amine-containing metabolites in mouse urine. The variability of concentrations of identified metabolites in urine samples from different mouse individuals was illustrated by the ratios of reporter ion intensities acquired from online data-dependent analysis.

Custom 4-Plex DiLeu Isobaric Labels Enable Relative Quantification of Urinary Proteins in Men with Lower Urinary Tract Symptoms (LUTS)

The relative quantification of proteins using liquid chromatography mass spectrometry (LC-MS) has allowed researchers to compile lists of potential disease markers. These complex quantitative workflows often include isobaric labeling of enzymatically-produced peptides to analyze their relative abundances across multiple samples in a single LC-MS run. Recent efforts by our lab have provided scientists with cost-effective alternatives to expensive commercial labels. Although the quantitative performance of these dimethyl leucine (DiLeu) labels has been reported using known ratios of complex protein and peptide standards, their potential in large-scale proteomics studies using a clinically relevant system has never been investigated. Our work rectifies this oversight by implementing 4-plex DiLeu to quantify proteins in the urine of aging human males who suffer from lower urinary tract symptoms (LUTS). Protein abundances in 25 LUTS and 15 control patients were compared, revealing that of the 836 proteins quantified, 50 were found to be differentially expressed (>20% change) and statistically significant (p-value <0.05). Gene ontology (GO) analysis of the differentiated proteins showed that many were involved in inflammatory responses and implicated in fibrosis. While confirmation of individual protein abundance changes would be required to verify protein expression, this study represents the first report using the custom isobaric label, 4-plex DiLeu, to quantify protein abundances in a clinically relevant system.

Development and characterization of novel 8-plex DiLeu isobaric labels for quantitative proteomics and peptidomics

RATIONALE

Relative quantification of proteins via their enzymatically digested peptide products determines disease biomarker candidate lists in discovery studies. Isobaric label-based strategies using TMT and iTRAQ allow for up to 10 samples to be multiplexed in one experiment, but their expense limits their use. The demand for cost-effective tagging reagents capable of multiplexing many samples led us to develop an 8-plex version of our isobaric labeling reagent, DiLeu.

METHODS

The original 4-plex DiLeu reagent was extended to an 8-plex set by coupling isotopic variants of dimethylated leucine to an alanine balance group designed to offset the increasing mass of the label's reporter group. Tryptic peptides from a single protein digest, a protein mixture digest, and Saccharomyces cerevisiae lysate digest were labeled with 8-plex DiLeu and analyzed via nanospray liquid chromatography/tandem mass spectrometry (nanoLC/MS(2) ) on a Q-Exactive Orbitrap mass spectrometer. Characteristics of 8-plex DiLeu-labeled peptides, including quantitative accuracy and fragmentation, were examined.

RESULTS

An 8-plex set of DiLeu reagents with 1 Da spaced reporters was synthesized at a yield of 36%. The average cost to label eight 100 µg peptide samples was calculated to be approximately $15. Normalized collision energy tests on the Q-Exactive revealed that a higher-energy collisional dissociation value of 27 generated the optimum number of high-quality spectral matches. Relative quantification of DiLeu-labeled peptides yielded normalized median ratios accurate to within 12% of their expected values.

CONCLUSIONS

Cost-effective 8-plex DiLeu reagents can be synthesized and applied to relative peptide and protein quantification. These labels increase the multiplexing capacity of our previous 4-plex implementation without requiring high-resolution instrumentation to resolve reporter ion signals.

Novel isotopic N,N-dimethyl leucine (iDiLeu) reagents enable absolute quantification of peptides and proteins using a standard curve approach

Absolute quantification of protein targets using liquid chromatography-mass spectrometry (LC-MS) is a key component of candidate biomarker validation. One popular method combines multiple reaction monitoring (MRM) using a triple quadrupole instrument with stable isotope-labeled standards (SIS) for absolute quantification (AQUA). LC-MRM AQUA assays are sensitive and specific, but they are also expensive because of the cost of synthesizing stable isotope peptide standards. While the chemical modification approach using mass differential tags for relative and absolute quantification (mTRAQ) represents a more economical approach when quantifying large numbers of peptides, these reagents are costly and still suffer from lower throughput because only two concentration values per peptide can be obtained in a single LC-MS run. Here, we have developed and applied a set of five novel mass difference reagents, isotopic N,N-dimethyl leucine (iDiLeu). These labels contain an amine reactive group, triazine ester, are cost effective because of their synthetic simplicity, and have increased throughput compared with previous LC-MS quantification methods by allowing construction of a four-point standard curve in one run. iDiLeu-labeled peptides show remarkably similar retention time shifts, slightly lower energy thresholds for higher-energy collisional dissociation (HCD) fragmentation, and high quantification accuracy for trypsin-digested protein samples (median errors <15%). By spiking in an iDiLeu-labeled neuropeptide, allatostatin, into mouse urine matrix, two quantification methods are validated. The first uses one labeled peptide as an internal standard to normalize labeled peptide peak areas across runs (<19% error), whereas the second enables standard curve creation and analyte quantification in one run (<8% error).

High-resolution enabled 12-plex DiLeu isobaric tags for quantitative proteomics

Multiplex isobaric tags (e.g., tandem mass tags (TMT) and isobaric tags for relative and absolute quantification (iTRAQ)) are a valuable tool for high-throughput mass spectrometry based quantitative proteomics. We have developed our own multiplex isobaric tags, DiLeu, that feature quantitative performance on par with commercial offerings but can be readily synthesized in-house as a cost-effective alternative. In this work, we achieve a 3-fold increase in the multiplexing capacity of the DiLeu reagent without increasing structural complexity by exploiting mass defects that arise from selective incorporation of ¹³C, ¹⁵N, and ²H stable isotopes in the reporter group. The inclusion of eight new reporter isotopologues that differ in mass from the existing four reporters by intervals of 6 mDa yields a 12-plex isobaric set that preserves the synthetic simplicity and quantitative performance of the original implementation. We show that the new reporter variants can be baseline-resolved in high-resolution higher-energy C-trap dissociation (HCD) spectra, and we demonstrate accurate 12-plex quantitation of a DiLeu-labeled Saccharomyces cerevisiae lysate digest via high-resolution nano liquid chromatography–tandem mass spectrometry (nanoLC–MS²) analysis on an Orbitrap Elite mass spectrometer.

Visualizing neurotransmitters and metabolites in the central nervous system by high resolution and high accuracy mass spectrometric imaging

The spatial localization and molecular distribution of metabolites and neurotransmitters within biological organisms is of tremendous interest to neuroscientists. In comparison to conventional imaging techniques such as immunohistochemistry, matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging (MSI) has demonstrated its unique advantage by directly localizing the distribution of a wide range of biomolecules simultaneously from a tissue specimen. Although MALDI-MSI of metabolites and neurotransmitters is hindered by numerous matrix-derived peaks, high-resolution and high-accuracy mass spectrometers (HRMS) allow differentiation of endogenous analytes from matrix peaks, unambiguously obtaining biomolecular distributions. In this study, we present MSI of metabolites and neurotransmitters in rodent and crustacean central nervous systems acquired on HRMS. Results were compared with those obtained from a medium-resolution mass spectrometer (MRMS), tandem time-of-flight instrument, to demonstrate the power and unique advantages of HRMSI and reveal how this new tool would benefit molecular imaging applications in neuroscience.

Mass spectrometric evaluation of neuropeptidomic profiles upon heat stabilization treatment of neuroendocrine tissues in crustaceans

Tissue heat stabilization is a vital component in successful mammalian neuropeptidomic studies. Heat stabilization using focused microwave irradiation, conventional microwave irradiation, boiling, and treatment with the Denator Stabilizor T1 have all proven effective in arresting post-mortem protein degradation. Although research has reported the presence of protein fragments in crustacean hemolymph when protease inhibitors were not added to the sample, the degree to which post-mortem protease activity affects neuropeptidomic tissue studies in crustacean species has not been investigated in depth. This work examines the need for Stabilizor T1 or boiling tissue stabilization methods for neuropeptide studies of Callinectes sapidus (blue crab) pericardial organ tissue. Neuropeptides in stabilized and nonstabilized tissue were extracted using acidified methanol or N,N-dimethylformamide (DMF) and analyzed by MALDI-TOF and nanoLC-ESI-MS/MS platforms. Post-mortem fragments did not dramatically affect MALDI analysis in the range m/z 650-1600, but observations in ESI MS/MS experiments suggest that putative post-mortem fragments can mask neuropeptide signal and add spectral complexity to crustacean neuropeptidomic studies. The impact of the added spectral complexity did not dramatically affect the number of detected neuropeptides between stabilized and nonstabilized tissues. However, it is prudent that neuropeptidomic studies of crustacean species include a preliminary experiment using the heat stabilization method to assess the extent of neuropeptide masking by larger, highly charged molecular species.

Comparison of NIMS and MALDI platforms for neuropeptide and lipid mass spectrometric imaging in C. borealis brain tissue

Nanostructure-initiator mass spectrometry (NIMS) is a recently developed matrix-free laser desorption/ionization technique that has shown promise for peptide analyses. It is also useful in mass spectrometric imaging (MSI) studies of small molecule drugs, metabolites, and lipids, minimizing analyte diffusion caused by matrix application. In this study, NIMS and matrix-assisted laser desorption/ionization (MALDI) MSI of a crustacean model organism Cancer borealis brain were compared. MALDI was found to perform better than NIMS in these neuropeptide imaging experiments. Twelve neuropeptides were identified in MALDI MSI experiments whereas none were identified in NIMS MSI experiments. In addition, lipid profiles were compared using each ionization method. Both techniques provided similar lipid profiles in the m/z range 700 - 900.

Dolphin shows and interaction programs: benefits for conservation education?

Dolphin shows and dolphin interaction programs are two types of education programs within zoological institutions used to educate visitors about dolphins and the marine environment. The current study examined the short- and long-term effects of these programs on visitors' conservation-related knowledge, attitude, and behavior. Participants of both dolphin shows and interaction programs demonstrated a significant short-term increase in knowledge, attitudes, and behavioral intentions. Three months following the experience, participants of both dolphin shows and interaction programs retained the knowledge learned during their experience and reported engaging in more conservation-related behaviors. Additionally, the number of dolphin shows attended in the past was a significant predictor of recent conservation-related behavior suggesting that repetition of these types of experiences may be important in inspiring people to conservation action. These results suggest that both dolphin shows and dolphin interaction programs can be an important part of a conservation education program for visitors of zoological facilities.

Mass spectrometry imaging for drugs and metabolites

Mass spectrometric imaging (MSI) is a powerful analytical technique that provides two- and three-dimensional spatial maps of multiple compounds in a single experiment. This technique has been routinely applied to protein, peptide, and lipid molecules with much less research reporting small molecule distributions, especially pharmaceutical drugs. This review's main focus is to provide readers with an up-to-date description of the substrates and compounds that have been analyzed for drug and metabolite composition using MSI technology. Additionally, ionization techniques, sample preparation, and instrumentation developments are discussed.

A simulation study on the abatement of CO2 emissions by de-absorption with monoethanolamine

Because of the adverse effect of CO2 from fossil fuel combustion on the earth's ecosystems, the most cost-effective method for CO2 capture is an important area of research. The predominant process for CO2 capture currently employed by industry is chemical absorption in amine solutions. A dynamic model for the de-absorption process was developed with monoethanolamine (MEA) solution. Henry's law was used for modelling the vapour phase equilibrium of the CO2, and fugacity ratios calculated by the Peng-Robinson equation of state (EOS) were used for H2O, MEA, N2 and O2. Chemical reactions between CO2 and MEA were included in the model along with the enhancement factor for chemical absorption. Liquid and vapour energy balances were developed to calculate the liquid and vapour temperature, respectively.

A computer-assisted administration of the Continuous Visual Memory Test

The Continuous Visual Memory Test (CVMT) is a continuous design recognition test designed for the assessment of visual memory for clinical and research applications. Comparisons were made between the traditional and a computer-assisted format of the CVMT using 51 university students. Formats were compared on five CVMT dependent measures, concurrent validity, split-half reliability, and selected dependent measures from the California Verbal Learning Test (CVLT). Participants scored higher on the computer format dependent measures, with the exception of false alarms (new items incorrectly identified as old), which remained comparable between formats. Adequate concurrent validity (r =.70) and split-half reliability (rs =.61-.70) were demonstrated for CVMT Total Score. Restriction of range and ceiling effects precluded reliability and validity conclusions for CVMT Delay. The computer format showed a nonsignificant trend towards lower correlations with CVLT dependent measures.

Canonical correlation and chi-square: relationships and interpretation

A 2 x 2 chi-square can be computed from a phi coefficient, which is the Pearson correlation between two binomial variables. Similarly, chi-square for larger contingency tables can be computed from canonical correlation coefficients. The authors address the following series of issues involving this relationship: (a) how to represent a contingency table in terms of a correlation matrix involving r - 1 row and c - 1 column dummy predictors; (b) how to compute chi-square from canonical correlations solved from this matrix; (c) how to compute loadings for the omitted row and column variables; and (d) the possible interpretive advantage of describing canonical relationships that comprise chi-square, together with some examples. The proposed procedures integrate chi-square analysis of contingency tables with general correlational theory and serve as an introduction to some recent methods of analysis more widely known by sociologists.

The role of extreme events in the impacts of selective tropical forestry on erosion during harvesting and recovery phases at Danum Valley, Sabah

Ten years' hydrological investigations at Danum have provided strong evidence of the effects of extremes of drought, as in the April 1992 El Niño southern oscillation event, and flood, as in January 1996. The 1.5 km2 undisturbed forest control catchment experienced a complete drying out of the stream for the whole 1.5 km of defined channel above the gauging station in 1992, but concentrated surface flow along every declivity from within a few metres of the catchment divide after the exceptional rains of 19 January 1996. Under these natural conditions, erosion is episodic. Sediment is discharged in pulses caused by storm events, collapse of debris dams and occasional landslips. Disturbance by logging accentuates this irregular regime. In the first few months following disturbance, a wave of sediment is moved by each storm, but over subsequent years, rare events scour sediment from bare areas, gullies and channel deposits. The spatial distribution of sediment sources changes with time after logging, as bare areas on slopes are revegetated and small gullies are filled with debris. Extreme storm events, as in January 1996, cause logging roads to collapse, with landslides leading to surges of sediment into channels, reactivating the pulsed sediment delivery by every storm that happened immediately after logging. These effects are not dampened out with increasing catchment scale. Even the 721 km2 Sungai Segama has a sediment yield regime dominated by extreme events, the sediment yield in that single day on 19 January 1996 exceeding the annual sediment load in several previous years. In a large disturbed catchment, such road failures and logging-activity-induced mass movements increase the mud and silt in floodwaters affecting settlements downstream. Management systems require long-term sediment reduction strategies. This implies careful road design and good water movement regulation and erosion control throughout the logging process.

Using writing instruments: invariances in young children and adults

In 2 studies, developmental changes in variability associated with handwriting were investigated. In Study 1, variability in grip patterns and pen positioning relative to a flat surface were examined in 3- and 5-year-olds and adults. The results indicated that between 3 and 5 years of age there is a reduction in the number of grips that individual children routinely use and a reduction in variability associated with pen-surface positioning. In Study 2, the 3-year-old children who participated in Study 1 were tested 6 months later. In comparison to young 3-year-old children, older 3-year-olds use an adult grip pattern more often and are less variable in pen-surface positioning, although the use of multiple grip patterns is still common. The findings from both studies are considered in relation to prior research that emphasized modal patterns of motor development and newer work that uses developmental changes in variability to understand the acquisition of motor skill.

Behavior problems in children with diabetes: disentangling possible scoring confounds on the Child Behavior Checklist

OBJECTIVE

The Child Behavior Checklist (CBCL; T. M. Achenbach, 1991), when used to assess the behavior of children with diabetes, may contain confounds because some behavioral items can have a physiologic etiology, and may skew reports of behavioral disturbance.

METHODS

Two techniques were used to disentangle possible scoring confounds in the behavioral ratings of children with and without diabetes: (1) the Somatic Complaints scale was deleted, or (2) Diabetes Items, identified a priori with 89% agreement by nine medical personnel, were deleted.

RESULTS

As expected, with traditionally scored protocols, children with diabetes obtained higher Internalizing and Total Behavior Problem scores than controls. This group difference persisted whether the Somatic Complaints scale or the Diabetes Items were deleted.

CONCLUSIONS

Compared to controls, children with diabetes obtained mildly elevated scores on six of the eight CBCL scales, regardless of scoring method, suggesting that their mildly elevated behavioral profile is not confounded by physiologic symptomatology.

The effect of a comprehensive Medicaid expansion on physicians' obstetric practices in Washington State

BACKGROUND

In 1989 Washington State implemented a comprehensive expansion of its Medicaid perinatal program, augmenting services, increasing provider reimbursement, and broadening eligibility. This study examines the influence of this legislation on physicians' obstetric practices and attitudes toward caring for pregnant Medicaid patients.

METHODS

Family physicians and obstetrician-gynecologists were surveyed at the start and 18 months after the Medicaid expansion. The study sample comprised physicians responding to the survey in both years.

RESULTS

A greater proportion of family physicians provided unlimited obstetric care to Medicaid patients after the expansion. Sixty percent of family physicians and 56 percent of obstetrician-gynecologists were more willing to provide prenatal care to Medicaid patients as a result of the expansion. Physicians and their office staff were more comfortable with Medicaid patients in the later time period. Many physicians felt that they were better able to link their patients to a variety of social services after the expansion.

CONCLUSIONS

A Medicaid expansion program can increase provider participation in Medicaid and increase provider comfort in caring for Medicaid patients.

Family environment and the interrelation of family structure, child behavior, and metabolic control for children with diabetes

Examined perceptions of the family environment in a cross-regional sample of 90 families who had children with diabetes and 89 controls. Families were classified as either traditional (intact) or nontraditional (single-parent or blended families). Parents of children with diabetes reported less family expressiveness, which was a predictor of clinically higher levels of child behavior problems than controls. Parents in nontraditional families reported lower levels of organization, less emphasis on active-recreational pursuits, and more child behavior problems than traditional families. An additive effect of diabetes and nontraditional family structure was found for children with diabetes from nontraditional families, who reported substantially less cohesion than all other groups. Nontraditional family structure was more disruptive for children with diabetes than for controls; it was the best predictor of behavior problems and was related to poorer metabolic control.

Implementation issues in generalist education

Devising a strategy for the implementation of a generalist medical educational program can be aided by grouping the many issues to be addressed into developmental stages. In this way, problems can be anticipated and resources marshalled. Initially, leadership and institutional support for the program must be developed. Next, detailed financial, curricular, and site planning must be undertaken. Implementation of the program must contend with faculty, site, and trainee concerns while consolidating financial and institutional support. Finally, in institutionalizing the program, financing must be secured and ongoing evaluation should provide information necessary to regularly reassess the program and renew its goals.

A comparison of student clerkship experiences in community practices and residency-based clinics

BACKGROUND

In our required family medicine clerkship, we used data from student logbook records of clinical experience to compare the learning experiences of students in community practices and residency-based clinics.

METHODS

Sixty-eight University of Washington students collected data on patients seen during the final two weeks of their family medicine clerkships. We compared patient demographics, location of patient encounters, and clinical problems seen at nine residency and eight community locations in a four-state area. National Ambulatory Medical Care Survey data were used to compare student experiences to national practices.

RESULTS

Log data documented that both community practices and residency sites met the course curriculum goals. Some variations occurred between the two types of clerkship sites, however. Students at community practices saw a higher mean number of patients and did more procedures than students at residency sites. Students at residencies were more likely to see patients for health maintenance and pregnancy care and less likely to see lacerations, sprains or strains, and some chronic diseases.

CONCLUSION

Episodic log data were successfully used to monitor the objective educational strategies for residency- and community-based student clerkship sites. Although all students met clerkship objectives, there were significant differences in certain aspects of students' clinical experiences at the two types of clerkship sites.

Thorotrast-induced ruptured hepatic angiosarcoma

The use of Thorotrast as a contrast medium is now of historical interest. Thorotrast-induced angiosarcoma, though rare, still generates considerable clinical interest because of the characteristic opacification of the liver, spleen, and lymph nodes, and the long latency period between exposure and the onset of the tumor. We present a case of hepatic angiosarcoma which developed 37 years after the administration of Thorotrast.

Differences in the obstetric malpractice claims filed by Medicaid and non-Medicaid patients

BACKGROUND

Many physicians believe Medicaid patients are more likely than non-Medicaid patients to file malpractice claims. This study examines the accuracy of this belief in regard to obstetric malpractice claims.

METHODS

Claims filed between January 1982 and June 1988 from the major malpractice insurer in Washington State were used to compare obstetric malpractice claims filed on behalf of Medicaid and non-Medicaid patients.

RESULTS

Eleven percent (7/62) of all closed obstetric claims were filed by Medicaid patients, whereas 19 percent of all births in Washington State were to Medicaid patients between 1982 and 1988. Failure to diagnose or treat a fetal condition was the most commonly alleged negligence in both Medicaid and non-Medicaid groups. Most claims in both groups were settled before the cases went to court; a substantial minority of claims were dropped. The mean cost of Medicaid claims ($406,984) was three times that of non-Medicaid claims ($133,743), suggesting that paid Medicaid claims were more severe than paid non-Medicaid claims.

CONCLUSIONS

Medicaid patients appear no more likely to file obstetric malpractice claims than non-Medicaid patients. The low likelihood of filing claims, coupled with large settlements, suggests that Medicaid patients may have less access to legal services than non-Medicaid patients.

Can physicians be induced to resume obstetric practice?

BACKGROUND

Decreased numbers of obstetric providers during the last decade have limited access to obstetrics care, especially for some groups of women. Increasing or stabilizing the number of providers could increase access.

METHODS

A questionnaire was mailed in 1989 to 1965 Washington State family physicians and obstetricians to determine their attitudes toward the practice of obstetrics. Sixty-six percent of physicians responded to the survey.

RESULTS

Of those who had quit obstetrics in the previous 3 years, 42 percent of responding family physicians and 19 percent of responding obstetricians would consider resuming. Those family physicians willing to consider resuming their obstetric practices were more likely to have been in practice fewer years, employed by a health maintenance organization (HMO), or located in a rural area. A majority of all respondents cited excessive malpractice premiums and fear of malpractice suit as reasons for stopping obstetric practice. Family physicians willing to consider resuming obstetrics were more concerned about the overall number of obstetric providers in their area. Rural family physicians willing to consider resuming obstetrics listed poor backup or shared call more often as a reason they had quit.

CONCLUSIONS

Attention targeted to the concerns of family physicians who have been in practice for a short time, who work for HMOs, or who are in rural practice might help induce some physicians to resume obstetrics.

Characteristics of physicians with obstetric malpractice claims experience

This study compared the demographic and practice characteristics of physicians with and without obstetric malpractice experience. The sample consisted of 387 family physicians and 204 obstetricians in Washington state who were insured for obstetrics by a major malpractice carrier between January 1982 and June 1988. Fifty-three physicians (9%) had an obstetric malpractice claim during the study period. The approximate overall rate of obstetric malpractice claims was low: 0.32 per 1000 deliveries. The higher the total delivery volume (exposure), the greater the chance of having malpractice experience. Although physicians with practices of over 200 deliveries per year were more likely to have had malpractice experience, their risk of malpractice experience per delivery was lower than that of providers doing fewer than 200 deliveries per year. Our work suggests that insurers might consider basing obstetric malpractice premiums on numbers of deliveries rather than specialty.

Comparing physicians' specialty interests upon entering medical school with their eventual practice specialties

The stability of specialty choices of 519 graduates of the University of Washington School of Medicine were studied by means of a mail survey in 1986. The graduates' actual practice specialties were compared with the one or more specialties each had indicated as possible career specialty choices when they entered medical school. Nearly 70% of the graduates' early choices remained stable, double the percentage found by other studies that based stability on an entering medical student's single choice of a career specialty. The findings suggest that students entering medical school have in mind a variety of acceptable specialties and later are likely to choose one of these as a career.

Specialty choice by medical students: recent graduate follow-up survey at the University of Washington

Understanding the factors that contribute to specialty choice by medical students is crucial if the proportion of physicians in primary care is to be increased. We surveyed 1,182 graduates of the University of Washington (1978-84) inquiring about residency training, current clinical specialty, influences and attributes in specialty selection, satisfaction with current specialty, and timing of the decision. Usable responses were 56% of the total surveyed (67% without 194 undeliverable surveys). When rates of non-response, bad address, and usable response were compared across graduating classes, no significant differences were found. The data also do not overrepresent a particular training choice or specialty group compared to all graduates. The majority of respondents (n = 404, 62.3%) were in practice at the time of the survey. The distribution of specialty groups was significantly different for those in practice compared to those still in training (X2 = 27.28, P less than .001). Although the groups were somewhat different, these differences did not lead to major changes in responses. Sixty percent of graduates choosing family medicine did so either before or during the first two years of medical school. This contrasts with other specialties, where the majority of students did not make a decision until the third year of medical school. Medical school courses were an important influence.(ABSTRACT TRUNCATED AT 250 WORDS)

Endocrine and immunologic studies in a patient with resistant ovary syndrome

A patient with the resistant ovary syndrome is reported. To evaluate the hypothesis that the hypogonadism might be the result of circulating antibodies to gonadotropin receptors or to an abnormal gonadotropin molecule, a series of clinical and laboratory studies was carried out. Administration of human menopausal gonadotropin had no effect on the serum estradiol level. The patient's serum did not affect follicle-stimulating hormone binding to a membrane preparation of monkey testes, suggesting the absence of antibodies to follicle-stimulating hormone receptors, nor did the patient's serum affect in vitro responsiveness of human granulosa cells to human menopausal gonadotropin. Unresponsiveness to exogenous gonadotropins, combined with anatomically normal follicular apparatus and the absence of serum antibodies to gonadotropin receptors, supports the concept of a gonadotropin receptor or a postreceptor defect.