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N Tucker

Publications and source records attributed to N Tucker.

14 recordsLinked to original sources
PubMed2005

DNA binding properties of the Escherichia coli nitric oxide sensor NorR: towards an understanding of the regulation of flavorubredoxin expression.

Nitric oxide is an intermediate of denitrification, and is one of the radical species deployed by macrophages against invading pathogens, therefore bacterial responses to NO are of considerable importance. The Escherichia coli flavorubredoxin and its associated oxidoreductase reduce NO to nitrous oxide under anaerobic conditions, and are encoded by the norVW transcription unit. Expression of norVW requires the NO sensing regulatory protein NorR and is dependent on RNA polymerase containing the alternative sigma factor, sigma(54). We have purified NorR and shown that it binds to three sites in the norVW promoter region, located 75-140 bp upstream of the experimentally verified transcription start site. We have also identified two binding sites for the integration host factor, one between the NorR sites and the sigma(54)-RNA polymerase binding site, and a second downstream of the norVW transcription start site. Comparison of the norVW promoters of enteric bacteria along with known and putative NorR-regulated promoters from Vibrio, Ralstonia and Pseudomonas species suggests that NorR binding sites contain an invariant GT(N7)AC motif flanking an AT-rich central region. The identification of a consensus for NorR binding sites will help to elucidate additional members of the NorR regulon.

Base Sequence↗
PubMed2001

Resolution of natural groups using iterative assignment tests: an example from two species of Australian native rats (Rattus).

Sympatric individuals of Rattus fuscipes and Rattus leucopus, two Australian native rats from the tropical wet forests of north Queensland, are difficult to distinguish morphologically and are often confused in the field. When we started a study on fine-scale movements of these species, using microsatellite markers, we found that the species as identified in the field did not form coherent genetic groups. In this study, we examined the potential of an iterative process of genetic assignment to separate specimens from distinct (e.g. species, populations) natural groups. Five loci with extensive overlap in allele distributions between species were used for the iterative process. Samples were randomly distributed into two starting groups of equal size and then subjected to the test. At each iteration, misassigned samples switched groups, and the output groups from a given round of assignment formed the input groups for the next round. All samples were assigned correctly on the 10th iteration, in which two genetic groups were clearly separated. Mitochondrial DNA sequences were obtained from samples from each genetic group identified by assignment, together with those of museum voucher specimens, to assess which species corresponded to which genetic group. The iterative procedure was also used to resolve groups within species, adequately separating the genetically identified R. leucopus from our two sampling sites. These results show that the iterative assignment process can correctly differentiate samples into their appropriate natural groups when diagnostic genetic markers are not available, which allowed us to resolve accurately the two R. leucopus and R. fuscipes species. Our approach provides an analytical tool that may be applicable to a broad variety of situations where genetic groups need to be resolved.

Alleles↗
PubMed1997

Thymic carcinoma metastatic to the orbit.

PURPOSE: To report a case of small cell carcinoma of the thymus metastatic to the orbit. METHODS: At age 37 years, a man who had been previously diagnosed and treated for small cell carcinoma of the thymus was initially examined for vertical diplopia and left proptosis. Computed tomographic scan disclosed a soft tissue mass in the superior aspect of the left orbit. A fine-needle aspiration biopsy of the mass was performed and submitted for cytopathologic examination. RESULT: The cytopathology and immunopathology disclosed malignant cells consistent with metastatic small cell thymic carcinoma. CONCLUSION: This is the first reported case of a primary thymus gland tumor metastatic to the orbit.

Adult↗
PubMed1997

Clinically suspected primary acquired nasolacrimal duct obstruction: clinicopathologic review of 150 patients.

PURPOSE: The incidence of lacrimal sac pathology in patients with clinically suspected primary acquired nasolacrimal duct obstruction is unknown. This is an important issue when considering the potential risk of either conservative nonsurgical management or laser dacryocystorhinostomy, neither of which permits direct visualization and biopsy of the lacrimal outflow apparatus. METHODS: A total of 162 lacrimal sac biopsy specimens were obtained in 150 consecutive patients undergoing external or endonasal dacryocystorhinostomy for clinical primary acquired nasolacrimal duct obstruction from January 1992 to October 1994. RESULTS: A total of 147 patients (98%) had histopathologic findings consistent with inflammation or fibrosis of the lacrimal sac or both. In the remaining three patients, abnormalities included sarcoid granuloma (one patient), oncocytoma (one patient), and lymphoma (one patient). CONCLUSIONS: The incidence of significant pathology of the lacrimal sac in clinically suspected primary acquired nasolacrimal duct obstruction is low. However, these cases can be identified correctly only by routine biopsy of the lacrimal sac during dacryocystorhinostomy.

Adult↗
PubMed1995

Efficacy of unanesthetized spiral computed tomography scanning in initial evaluation of childhood leukocoria.

PURPOSE: To evaluate the use of spiral/helical computed tomography (CT) in the preoperative evaluation of pediatric leukocoria. METHODS: A total of 34 patient charts and imaging studies were reviewed from a consecutive series of children referred with the diagnosis of presumed retinoblastoma. Of these patients, 31 had a confirmed diagnosis of retinoblastoma. Three patients had simulating lesions, including one patient with persistent hyperplastic primary vitreous and two with Coats disease. RESULTS: In all patients, a diagnosis of intraocular retinoblastoma could be established or excluded at the same clinical level by spiral CT as by conventional CT. Spiral CT of the eye, orbit, and midline structures was performed without a requirement for patient anesthesia. This technique resulted in a reduced volume of contrast material required for evaluation of the central nervous system and a small decrease in total radiation exposure. There was an attendant reduction in the amount of monitoring equipment required and the necessity for attending anesthesia staff. CONCLUSIONS: The primary advantage of spiral CT is reduced anesthesia risk in small children. In addition, this technique provides necessary clinical information with a reduction in image acquisition time, monitoring equipment, and monitoring staff.

Anesthesia↗
PubMed1994

Thyroid ophthalmopathy.

Thyroid ophthalmopathy, idiopathic orbital inflammation, and orbital infection can occasionally demonstrate overlapping clinical features. It is essential to distinguish between these processes because appropriate treatments are distinct in each case. In the past year, the pathophysiology of thyroid ophthalmopathy has been the topic of many reports. Orbital inflammation, particularly the fibrotic form, has been recognized to represent a distinct disease entity that may require more specifically directed treatment. In some cases cytotoxic therapies may be indicated. Orbital infection, particularly in the setting of orbital abscess, may be treated conservatively with antibiotic therapy and observation or more aggressively with surgical drainage procedures. In several recent studies, appropriate management of such infectious processes appears to be related to patient age, as well as to the specific clinical pattern of presentation.

Eye Diseases↗
PubMed1993

Interlocking Crawford triangles in frontalis suspension.

In Crawford's pattern of frontalis suspension, two bands are passed, one nasally and the other temporally, forming two base-down triangles with their apexes attached at the brow incisions. Over time, opposing vector forces in the center of the eyelid can cause "cheese-wiring" of the bands with resultant shortening of the inferior bases of both triangles and loosening of the suspensory loops. We modified the standard pattern by interlocking the bands centrally in the lid. A mathematical model was developed that demonstrates neutralization of these opposing forces, resulting in a symmetrical and flexible redistribution of the lifting forces. In support of this mathematical model, a retrospective analysis of 42 consecutive cases using this technique revealed good aesthetic results in terms of lid height, contour, and symmetry, with no important complications from this modification.

Adolescent↗
PubMed1993

Effect of a topical anesthetic cream (EMLA) in reducing pain caused by infiltration of local anesthetic in eyelid surgery.

EMLA (eutectic mixture of local anesthetics) cream is a topical formulation of a mixture of lidocaine and prilocaine. It has been used to achieve local analgesia after application under an occlusive dressing. We carried out a double-blind randomized controlled clinical trial to assess the effect of 5% EMLA (25 mg/mL of lidocaine and of prilocaine) in reducing the pain caused by infiltration of local anesthetic in eyelid surgery. Pain was assessed by means of a modified visual analogue scale ranging from 0 (no pain) to 10 (excruciating pain) in 25 consecutive patients (average age 65 years) undergoing bilateral eyelid surgery. Clinical significance was defined as a difference in pain scores of 3 or more between EMLA and placebo. The mean pain scores for EMLA and placebo were 3.1 and 4.0 respectively, a nonsignificant difference. The EMLA preparation was found not to be clinically effective in reducing pain caused by infiltration of local anesthetic in eyelid surgery.

Aged↗
PubMed1992

Orbital decompression for Graves' disease: exposure through a modified blepharoplasty incision.

A "transorbital" three-wall decompression through a modified blepharoplasty incision was used to treat 19 orbits for either cosmetic disfigurement or optic neuropathy. In the 14 orbits with disfigurement, surgical retroplacement averaged 5.2 mm; vision improved to 20/40 or better in four of five eyes with optic neuropathy. Complications attributed to the surgery included: acquired strabismus (two transient, one permanent) and infraorbital hypesthesia (one transient, one permanent). This technique's advantages are: 1) a single incision with wide exposure, 2) a low incidence of permanent strabismus, 3) a lateral orbital rim and canthal tendon preservation, and 4) a large reduction in proptosis.

Adult↗
PubMed1990

What do psychiatric emergency patients really want and how do they feel about what they get?

Psychiatric emergency patients range along a continuum from persons who present to the service with specific requests for help, to individuals who are brought to the service in handcuffs against their will for reasons they do not understand. In addition, studies suggest that psychiatric emergency patients' wishes and expectations often fall outside the traditional framework of psychiatric assessment, are not straightforward or concrete or are not accurately perceived by the clinicians who see them. How these factors impact on patient satisfaction with the treatment they have received is not well-understood, because the manner in which specific patient variables and treatments might relate to patient satisfaction among the psychiatric emergency service population has not been systematically studied. In contrast, psychiatric inpatients and outpatients usually express positive attitudes about their mental health care, although this finding may be skewed by a lack of real anonymity. Chronic patients tend to express less satisfaction with their treatment programs than do others, and patient satisfaction in some studies has been related to patient demographics, diagnoses, treatment histories and patients' global rating of treatment outcome.

Consumer Behavior↗
PubMedDate not supplied

Relationship of endomysial antibodies to jejunal mucosal pathology: specificity towards both symptomatic and asymptomatic celiacs.

Serum immunoglobulin A class antibodies reactive to the endomysial lining of the smooth muscle bundles of the gastrointestinal tract have recently been reported to be specific and sensitive indicators of celiac disease (CD). A total of 203 subjects were examined for serum endomysial antibodies (EmA) and in 103 small bowel biopsies were obtained. EmA were detected in 43 cases including 26 CD patients evaluated during the gluten challenge phase of diagnosis by European Society for Pediatric Gastroenterology and Nutrition criteria, 11 of 53 symptomatic patients, and 6 asymptomatic family members. All patients with detectable antibody at the time of biopsy exhibited grade III-IV villous atrophy. Disaccharidase activities performed in 19 cases revealed severe deficiencies. EmA were not detected in 160 subjects including 42 infants and children with chronic nonspecific diarrhea. Eighteen of these possessed grade II-III villous atrophy with moderate disaccharidase deficiency and 24 were found to have normal histology and enzymes. The EmA were also not detected in 3 CD patients who were well maintained on a gluten-free diet for greater than 1 year and 25 asymptomatic family members exhibiting normal histology and enzymes. An additional 90 infants and children with other gastrointestinal and liver diseases were also negative for the serum EmA. Fourteen of these patients underwent biopsies and were demonstrated to have normal histology.

Adolescent↗