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Timothy D Anderson

Publications and source records attributed to Timothy D Anderson.

16 recordsLinked to original sources
PubMed2006

CpSufE activates the cysteine desulfurase CpNifS for chloroplastic Fe-S cluster formation.

CpNifS, a cysteine desulfurase required to supply sulfur for ironsulfur cluster biogenesis in Arabidopsis thaliana chloroplasts, belongs to a class of NifS-like enzymes with low endogenous cysteine desulfurase activity. Its bacterial homologue SufS is stimulated by SufE. Here we characterize the Arabidopsis chloroplast protein CpSufE, which has an N-terminal SufE-like domain and a C-terminal BolA-like domain unique to higher plants. CpSufE is targeted to the chloroplast stroma, indicated by green fluorescent protein localization and immunoblot experiments. Like CpNifS, CpSufE is expressed in all major tissues, with higher expression in green parts. Its expression is light-dependent and regulated at the mRNA level. The addition of purified recombinant CpSufE increased the Vmax for the cysteine desulfurase activity of CpNifS over 40-fold and decreased the KM toward cysteine from 0.1 to 0.043 mm. In contrast, CpSufE addition decreased the affinity of CpNifS for selenocysteine, as indicated by an increase in the KM from 2.9 to 4.17 mm, and decreased the Vmax for selenocysteine lyase activity by 30%. CpSufE forms dynamic complexes with CpNifS, indicated by gel filtration, native PAGE, and affinity chromatography experiments. A mutant of CpSufE in which the single cysteine was changed to serine was not active in stimulating CpNifS, although it did compete with WT CpSufE. The iron-sulfur cluster reconstitution activity of the CpNifS-CpSufE complex toward apoferredoxin was 20-fold higher than that of CpNifS alone. We conclude that CpNifS and CpSufE together form a cysteine desulfurase required for iron-sulfur cluster formation in chloroplasts.

Amino Acid Sequence↗
PubMed2005

Comparison of antibody array substrates and the use of glycerol to normalize spot morphology.

Antibody microarrays are a high-throughput proteomic technology used to examine the expression of multiple proteins in complex solutions. Antibody microarrays can be manufactured on a variety of commercially available activated glass or coated slides. The goal of this study was to compare Hydrogeltrade mark, nitrocellulose, aldehyde-silane and epoxy-silane slides to determine the amount of antibody bound. The optimal substrate was defined as one that bound the greatest amount of antibody with minimal background. Our studies found that epoxy-silane enhanced surface (ES) slides gave the greatest degree of binding along with a minimal background. However, larger antibody microarrays showed variability in spot size, high intra-spot coefficient of variation and drying artifacts. Increasing the amount of glycerol in the spotting buffer caused a dose-dependent improvement in overall spot morphology. Glycerol was tested on 128 different antibodies and showed decreased: mean spot diameter, intra-spot coefficient of variation and drying artifacts. These studies revealed that the optimal slide substrate was epoxy-silane ES microarray slides. Furthermore, glycerol could normalize spot size, decrease intra-spot coefficient of variability, decrease drying artifacts and increase antibody-spotting density.

Animals↗
PubMed2005

Development of an internally controlled antibody microarray.

Antibody microarrays are a high throughput technology used to concurrently screen for protein expression. Most antibody arrays currently used are based on the ELISA sandwich approach that uses two antibodies to screen for the expression of a limited number of proteins. Also because antigen-antibody interactions are concentration-dependent, antibody microarrays need to normalize the amount of antibody that is used. In response to the limitations with the currently existing technology we have developed a single antibody-based microarray where the quantity of antibody spotted is used to standardize the antigen concentration. In addition, this new array utilizes an internally controlled system where one color represents the amount of antibody spotted, and the other color represents the amount of the antigen that is used to quantify the level of protein expression. When compared with median fluorescence intensity alone, normalization for antibody spot intensity decreased variability and lowered the limits of detection. This new antibody array was tested using standard cytokine proteins and also cell lysates obtained from mouse macrophages stimulated in vitro and evaluated for the expression of the cytokine proteins interleukin (IL)-1beta, IL-5, IL-6, and macrophage inflammatory proteins 1alpha and 1beta. The levels of protein expression seen with the antibody microarray was compared with that obtained with Western blot analysis, and the magnitude of protein expression observed was similar with both technologies with the antibody array actually showing a greater degree of sensitivity. In summary, we have developed a new type of antibody microarray to screen for protein expression that utilizes a single antibody and controls for the amount of antibody spotted. This type of array appears at least as sensitive as Western blot analysis, and the technology can be scaled up for high throughput screening for hundreds of proteins in complex biofluids such as blood.

Animals↗
PubMed2005

Transnasal esophagoscopy: a high-yield diagnostic tool.

OBJECTIVES: Transnasal esophagoscopy (TNE) reveals a wide range of esophageal findings. TNE technique, indications, outcomes, advantages, limitations, and impact on patient care are described. STUDY DESIGN: Retrospective chart review. METHODS: Charts of the first 30 patients to undergo TNE in an academic otolaryngology practice were reviewed. Technique details, patient demographics, and procedure indications and findings as well as the disposition of patients in this series are described. TNE limitations are discussed with areas for future development. RESULTS: Thirty patients who underwent unsedated outpatient TNE by their otolaryngologist are described. TNE was directed toward select indications: dysphagia, screening esophagoscopy given long-standing gastroesophageal reflux (GER) or laryngopharyngeal reflux (LPR), and esophageal surveillance with a new diagnosis of head and neck squamous cell carcinoma. Positive findings included mucosal cobblestoning, Barrett's esophagus, esophagitis, gastritis, candidal esophagitis, esophageal diverticulum, postcricoid mass, patulous esophagus, and absence of secondary esophageal peristalsis. Outcomes included referral to a gastroenterologist for evaluation, with or without biopsy; direct laryngoscopy or esophagoscopy with biopsy by the otolaryngologist; planned cancer resection by the otolaryngologist; and medical management of GER/LPR by the otolaryngologist. CONCLUSIONS: With appropriate selection criteria, TNE yields a high percentage of positive findings and wide range of esophageal abnormalities, directly impacting patient management. Available to otolaryngologists in the outpatient setting, TNE expedites interventions by providing a safe, effective alternative to rigid esophagoscopy under general anesthesia and flexible upper endoscopy with sedation. Patients will benefit from the integration of TNE into otolaryngologists' outpatient diagnostic armamentarium.

Adult↗
PubMed2004

Complications of collagen injection of the vocal fold: report of several unusual cases and review of the literature.

UNLABELLED: Injection laryngoplasty is one of the most frequently performed procedures in patients with voice complaints. Various biomaterials have been used to medialize vocal folds or to treat symptoms of vocal fold scar. The ideal biomaterial would be easily injected through a fine-gauge needle, well tolerated, and long lasting. Injectable collagen preparations fulfill at least two of these criteria, and collagen has been used widely for vocal fold injections. MATERIALS AND METHODS: We present a retrospective review of two unusual complications of collagen injection and a review of the relevant literature on the complications of medical use of collagen compounds. RESULTS: Two patients in whom collagen was injected formed firm submucosal deposits that interrupted the normal mucosal wave and produced significant dysphonia. Surgical removal of these deposits restored the mucosal wave and improved voice quality. Management of this unusual complication of human collagen injection in the vocal fold has not been reported previously. Other complications of collagen injection include hypersensitivity reactions to bovine collagen, local abscess formation at injection sites, and possibly induction of collagen vascular disease in some patients. CONCLUSIONS: Although collagen injections of the vocal fold rarely result in complications, physicians using collagen must be familiar with the types of complications that can occur. Proper diagnosis and prompt management of complications can result in good outcomes.

Adult↗
PubMed2003

Immunologic characterization of spasmodic dysphonia patients who develop resistance to botulinum toxin.

The immune status of six spasmodic dysphonia patients who became resistant to botulinum toxin was compared to that of a series of patients who remained responsive. The two groups were similar in terms of age, sex, and cumulative dose of toxin. Five of the resistant patients had a significant titer of anti-botulinum toxin IgG antibodies, as determined by enzyme-linked immunosorbent assay (ELISA). These same five resistant patients had a circulating titer of anti-heavy chain antibodies, but only three of these patients had a circulating titer of anti-light chain antibodies, as determined by Western blotting. By contrast, none of the responsive patients had antibodies against the holotoxin or its two chains. Interestingly, two of the resistant patients also had a low circulating titer of anti-botulinum toxin IgA antibodies. None of the responsive patients was IgA-positive. The cumulative dose of botulinum toxin administered to resistant patients was lower than that customarily associated with emergence of immunity in dystonia patients.

Adult↗
PubMed2003

Thyroplasty revisions: frequency and predictive factors.

UNLABELLED: Thyroplasty is the most commonly performed type of laryngeal framework surgery, and the surgical indications are gradually being expanded. Although many reports have described thyroplasty results and rates of success, no study has attempted to determine predictors of the need for revisions or other secondary surgical procedures. METHODS: Retrospective review of 118 primary thyroplasty procedures performed on 96 patients. Secondary surgical procedures were divided into planned second-stage procedures (all fat implantation due to scarring), touchup procedures (primarily fat or collagen injections to close localized glottic gaps), and thyroplasty revisions (for implant extrusion or slippage). Statistical analysis was performed via the chi-squared technique with p < 0.05 considered significant. RESULTS: 96 patients underwent thyroplasty, 58 for vocal fold paresis or paralysis and 38 for other indications. Thirty-two (33%) patients underwent secondary surgical procedures, including 4 planned second stage procedures, and 6 patients with progression of their underlying disease. Thirty-two secondary procedures were performed in the other 22 patients. Professional singers were found to be more likely to require touchup or planned second-stage procedures (p = 0.029). Patients with abnormal preoperative noise-toharmonic ratios were more likely to undergo secondary surgeries (p = 0.039). Maximum phonation time was not associated with need for secondary surgery. Implant material did not influence revision rates. CONCLUSIONS: Professional singers and those patients with severe voice disorders (as measured by more abnormal noise-to-harmonic ratios) are more likely to undergo secondary surgical procedures. The choice of implant material does not affect need for secondary surgical procedures.

Adolescent↗
PubMed2002

Desmoplastic neurotropic melanoma of the head and neck: the role of radiation therapy.

BACKGROUND: Desmoplastic neurotropic melanoma (DNM) is an uncommon cutaneous melanoma variant with pronounced neurotropism. In contrast to ordinary melanomas, locoregional recurrences are common and distant metastasis are uncommon in patients with DNM. Local control with surgery and radiation therapy may assume a more important role in this variant of melanoma. We present a case of an unresectable skull base recurrence of DNM that was controlled using radiation therapy alone and review the literature. METHODS: Case report with 36-month follow-up. RESULTS: The patient is a 68-year-old with multiple recurrences of a DNM that originated on the forehead. After extensive surgery, including total parotidectomy and temporal bone resection, the patient had an unresectable recurrence of the skull base develop. This was treated with definitive radiation therapy, resulting in a complete response. The patient has had no evidence of recurrence at 3 years. CONCLUSIONS: DNM is a locally aggressive type of melanoma with a high risk of local recurrence that can be radioresponsive. The incidence of distant metastasis is low, so aggressive treatment to control local disease is warranted. This may include surgery plus adjuvant radiation therapy or definitive radiotherapy for unresectable recurrences.

Aged↗
PubMed2002

Airway complications of infant botulism: ten-year experience with 60 cases.

OBJECTIVE: The study goal was to understand the incidence, etiology, and management of airway complications in infant botulism. METHODS: We conducted a retrospective review of the period from January 1, 1987, to December 31, 1997. SETTING: Urban tertiary care children's hospital. RESULTS: Of 60 children with infant botulism, 37 (61.7%) required endotracheal intubation for a mean of 21 days. No patient required a tracheostomy. Airway complications (stridor, subglottic stenosis, granuloma formation) occurred in 5 (13.5%) of 37 patients, with 3 requiring surgical bronchoscopy. Of the 37 children, 14 (37.8%), including 4 with airway complications, had endotracheal tube leak pressures recorded. In 3 (50%) of 6 patients with measured leak pressures of greater than 40 cm H2O, airway complications developed. Complications did not develop in patients with leak pressures of less than 20 cm H2O. No correlation between length of intubation and complications could be established. CONCLUSION: Airway complications in infant botulism may be accompanied by high leak pressures and can be managed with endoscopic techniques. The study data suggest that leak pressures should be measured on a regular basis and maintained at less than 20 to 25 cm H2O. A prospective trial to study this issue is warranted. Tracheotomy is not routinely necessary. A high index of suspicion, early diagnosis, and prompt intervention are required for the optimal management of airway complications in infant botulism.

Botulism↗