St Louis University Medical School

St. Louis, MO, United States

St Louis University Medical School

St. Louis, MO, United States
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Panneton W.M.,St Louis University Medical School | Gan Q.,St Louis University Medical School
Frontiers in Neuroscience | Year: 2014

Few trigeminal sensory fibers project centrally beyond the trigeminal sensory complex, with only projections of fibers carried in its sensory anterior ethmoidal (AEN) and intraoral nerves described. Fibers of the AEN project into the brainstem reticular formation where immunoreactivity against substance P and CGRP are found. We investigated whether the source of these peptides could be from trigeminal ganglion neurons by performing unilateral rhizotomies of the trigeminal root and looking for absence of label. After an 8-14 days survival, substance P immunoreactivity in the trigeminal sensory complex was diminished, but we could not conclude that the sole source of this peptide in the lateral parabrachial area and lateral reticular formation arises from primary afferent fibers. Immunoreactivity to CGRP after rhizotomy however was greatly diminished in the trigeminal sensory complex, confirming the observations of others. Moreover, CGRP immunoreactivity was nearly eliminated in fibers in the lateral parabrachial area, the caudal ventrolateral medulla, both the peri-ambiguus and ventral parts of the rostral ventrolateral medulla, in the external formation of the nucleus ambiguus, and diminished in the caudal pressor area. The nearly complete elimination of CGRP in the lateral reticular formation after rhizotomy suggests this peptide is carried in primary afferent fibers. Moreover, the arborization of CGRP immunoreactive fibers in these areas mimics that of direct projections from the AEN. Since electrical stimulation of the AEN induces cardiorespiratory adjustments including an apnea, peripheral vasoconstriction, and bradycardia similar to those seen in the mammalian diving response, we suggest these perturbations of autonomic behavior are enhanced by direct somatic primary afferent projections to these reticular neurons. We believe this to be first description of potential direct somatoautonomic projections to brainstem neurons regulating autonomic activity. © 2014 Panneton and Gan.

Strober B.E.,University of Connecticut | Armour K.,Alfred Hospital | Romiti R.,University of Sao Paulo | Smith C.,St Johns Institute Of Dermatology | And 3 more authors.
Journal of the American Academy of Dermatology | Year: 2012

The entry of biosimilar forms of biopharmaceutical therapies for the treatment of psoriasis and other immune-mediated disorders has provoked considerable interest. Although dermatologists are accustomed to the use of a wide range of generic topical agents, recognition of key differences between original agent (ie, the name brand) and the generic or biosimilar agent is necessary to support optimal therapy management and patient care. In this review we have summarized the current state of the art related to the impending introduction of biosimilars into dermatology. Biosimilars represent important interventions that are less expensive and hence offer the potential to deliver benefit to large numbers of patients who may not currently be able to access these therapies. But the development of biosimilars is not equivalent to that of small molecule generic therapies because of differences in molecular structure and processes of manufacture. The planned regulatory guidelines and path to approval may not encompass all of these potentially important differences and this may have clinical relevance to the prescriber and patient. Consequently, we have identified a series of key issues that should be considered to support the full potential of biosimilars for the treatment of psoriasis; ie, that of increased access to appropriate therapy for the psoriasis population worldwide. © 2010 by the American Academy of Dermatology, Inc.

Heyduk E.,St Louis University Medical School | Heyduk T.,St Louis University Medical School
Biochemistry | Year: 2014

Promoter melting by bacterial RNA polymerase is a key step in transcription initiation. We used a next generation sequencing (NGS) based approach to analyze in parallel promoter melting of all 4096 sequence variants of the 6 bp -10 promoter element. We used NGS read count for each sequence of a promoter library containing a randomized -10 sequence as an observable to determine relative enrichment of -10 element sequence variants at different time points of the promoter melting reaction. The analysis reinforced the dominating role of consensus bases at positions -11 and -7, demonstrated an enhanced preference for A at -11 among sequences exhibiting the fastest melting kinetics, and showed higher overall importance of the T at -7 compared to the A at -11 for efficient promoter melting. Sequences lacking the consensus bases at -7 or -11 could still melt fast if they contained compensatory base patterns at other positions. We observed a significant correlation between the duplex melting energy of -10 element and the kinetics of promoter melting that became more pronounced when the dominating base-specific interactions with RNAP were diminished. These observations indicate that promoter melting kinetics is determined by a combination of base-specific effects/interactions and sequence-dependent stability of DNA duplex with the former playing a dominating role. Our data show that NGS can provide a reliable, quantitative readout for a highly parallel analysis of DNA template sequence dependence of activities of proteins that bind or operate on a DNA template. © 2013 American Chemical Society.

Ko J.,St Louis University Medical School | Heyduk T.,St Louis University Medical School
Biochemical Journal | Year: 2014

Promoter escape by RNA polymerase, the transition between the initiation and elongation, is a critical step that defines transcription output at many promoters. In the present study we used a realtime fluorescence assay for promoter melting and escape to study the determinants of the escape. Perturbation of core promoter- polymerase contacts had opposing effects on the rates of melting and escape, demonstrating a direct role of core promoter elements sequence in setting not only the kinetics of promoter melting, but also the kinetics of promoter escape. The start of RNA synthesis is accompanied by an enlargement of the transcription bubble and pulling in of the downstream DNA into the enzyme, resulting in DNA scrunching. Promoter escape results in collapse of the enlarged bubble. To test whether the energy that could be potentially released by the collapse of the bubble plays a role in determining escape kinetics, we measured the rates of promoter escape in promoter constructs, in which the amount of this energy was perturbed by introducing sequence mismatches. We found no significant changes in the rate of promoter escape with these promoter constructs suggesting that the energy released upon bubble collapse does not play a critical role in determining the kinetics of promoter escape. © 2014 Biochemical Society.

Lass-Napiorkowska A.,St Louis University Medical School | Heyduk E.,St Louis University Medical School | Tian L.,St Louis University Medical School | Tian L.,Mediomics, Llc | Heyduk T.,St Louis University Medical School
Analytical Chemistry | Year: 2012

We have recently developed a mix-and-read format homogeneous antigen peptide based assay for detection of the antibodies (Tian, L.; Heyduk, T. Anal. Chem.2009, 81, 5218-5225) that employed for target detection a simple biophysical mechanism of target antibody induced annealing between two complementary oligonucleotides attached to the antigen peptide. In this work, we propose and experimentally validate an alternative variant of this assay format in which target antibody binding to antigen peptide-oligonucleotide conjugate produces a complex with high sequence-specific binding affinity to a single-stranded capture oligonucleotide. This new assay format can be used for preparing various solid-surface based assays by immobilizing the capture oligonucleotide. This assay design is not limited to antibody detection. We demonstrate that it can also be employed for detecting proteins or pathogenic bacteria using oligonucleotide-labeled antibodies as target recognition elements. Preparation of these solid-surface based assays is simplified because all interactions with the solid surfaces are mediated by well-understood oligonucleotide-oligonucleotide interactions and because of the relative ease of immobilizing oligonucleotides on various solid surfaces. These unique aspects of the assay design also allow microarray-style multiplexing that could be most useful for multiplexed antibody profiling for diagnosis and analysis of cancer, autoimmune, and infectious diseases. © 2012 American Chemical Society.

Rodin M.B.,St Louis University Medical School
Journal of Geriatric Oncology | Year: 2012

Geriatric oncology just makes sense. Cancers are age-associated diseases and one cannot treat one without attending to the other. We are in the phase of professional evolution now where we need to develop, test and report on models of care that fuse knowledge and tools of both fields. © 2011 Elsevier Inc.

Heyduk E.,St Louis University Medical School | Moxley M.M.,St Louis University Medical School | Salvatori A.,St Louis University Medical School | Corbett J.A.,University of Alabama at Birmingham | Heyduk T.,St Louis University Medical School
Diabetes | Year: 2010

OBJECTIVE - Glucose-stimulated islet insulin or C-peptide secretion experiments are a fundamental tool for studying and assessing islet function. The goal of this work was to develop Ab-based fluorescent homogenous sensors that would allow rapid, inexpensive, near-instantaneous determinations of insulin and C-peptide levels in biological samples. RESEARCH DESIGN AND METHODS - Our approach was to use molecular pincer design (Heyduk et al., Anal Chem 2008;80: 5152-5159) in which a pair of antibodies recognizing nonoverlapping epitopes of the target are modified with short fluorochrome-labeled complementary oligonucleotides and are used to generate a fluorescence energy transfer (FRET) signal in the presence of insulin or C-peptide. RESULTS - The sensors were capable of detecting insulin and C-peptide with high specificity and with picomolar concentration detection limits in times as short as 20 min. Insulin and C-peptide levels determined with the FRET sensors showed outstanding correlation with determinations performed under the same conditions with enzyme-linked immunosorbent assay. Most importantly, the sensors were capable of rapid and accurate determinations of insulin and C-peptide secreted from human or rodent islets, verifying their applicability for rapid assessment of islet function. CONCLUSIONS - The homogeneous, rapid, and uncomplicated nature of insulin and C-peptide FRET sensors allows rapid assessment of β-cell function and could enable point-of-care determinations of insulin and C-peptide. © 2010 by the American Diabetes Association.

Kriedt C.L.,St Louis University Medical School | Baldassare J.,St Louis University Medical School | Shah M.,St Louis University Medical School | Klein C.,St Louis University Medical School
Journal of Experimental Therapeutics and Oncology | Year: 2010

The effects of zinc on the viability of PC3, LNCaP and DU145 prostate cancer cell lines in vitro were examined. The data indicate that, despite their distinctly different gene expression profiles, morphology and tissue origin, all cell lines responded to zinc in a similar time and dose dependent manner. Experiments using pyrithione indicated that cell death is mediated by internalized zinc. Zinc effects on cells plated as monolayers were compared to its effects on cells plated in a collagen matrix. Although the rate of cell growth in the matrix was delayed compared to cells in 2-dimensional cultures, the cytotoxic effects of zinc were unaltered. Using both 2-dimensional and 3-dimensional cultures, we observed that zinc cytotoxicity was independent of both the cul-ture conditions and the rate of cell growth, results that contrast the activity of the current chemotherapeutics used to treat prostate cancer. The attractive properties of zinc cytotoxicity demonstrated in this paper suggest that is can be developed as a novel and effective chemotherapeutic agent for prostate cancer treatment. © 2010 Old City Publishing, Inc.

Heyduk E.,St Louis University Medical School | Heyduk T.,St Louis University Medical School
Analytical Biochemistry | Year: 2010

We developed a straightforward antibody-based assay for rapid homogeneous detection of bacteria. Our sensors utilize antibody recognizing cell-surface epitopes of the target cell. Two samples of the antibody are prepared, each labeled via nanometer size flexible linkers with short complementary oligonucleotides that are modified with fluorochromes that could participate in fluorescence resonance energy transfer (FRET). The length of the complementary oligonucleotide sequences was designed such that very little annealing occurred in the absence of the target cells. In the presence of the target cells the two labeled antibodies bind to the surface of the cell resulting in a large local concentration of the complementary oligonucleotides that are attached to the antibody. This in turn drives the annealing of the complementary oligonucleotides which brings the fluorescence probes to close proximity producing large FRET signals proportional to the amount of target cells. Long flexible linkers used to attach the oligonucleotides to the antibody enable target-induced oligonucleotide annealing even if the density of surface antigens is only modest. We used Escherichia coli 0157:H7 and Salmonella typhimurium to demonstrate that this design produced sensors exhibiting rapid response time, high specificity, and sensitivity in detecting the target bacteria. © 2009 Elsevier Inc. All rights reserved.

Heyduk E.,St Louis University Medical School | Heyduk T.,St Louis University Medical School
Analytical Biochemistry | Year: 2014

Detection of antibodies in serum has many important applications. Our goal was to develop a facile general experimental approach for identifying antibody-specific peptide ligands that could be used as the reagents for antibody detection. Our emphasis was on an approach that would allow identification of peptide ligands for antibodies in serum without the need to isolate the target antibody or to know the identity of its antigen. We combined ribosome display (RD) with the analysis of peptide libraries by next generation sequencing (NGS) of their coding RNA to facilitate identification of antibody-specific peptide ligands from random sequence peptide library. We first demonstrated, using purified antibodies, that with our approach-specific peptide ligands for antibodies with simple linear epitopes, as well as peptide mimotopes for antibodies recognizing complex epitopes, were readily identified. Inclusion of NGS analysis reduced the number of RD selection rounds that were required to identify specific ligands and facilitated discrimination between specific and spurious nonspecific sequences. We then used a model of human serum spiked with a known target antibody to develop NGS-based analysis that allowed identification of specific ligands for a target antibody in the context of an overwhelming amount of unrelated immunoglobins present in serum. © 2014 Elsevier Inc. All rights reserved.

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