Search PubMed⌕ Search

Biomedical subjects

Patrick Byrne

Publications and source records attributed to Patrick Byrne.

6 recordsLinked to original sources
PubMed2005

Altered phenotype of dextran sulfate sodium colitis in interferon regulatory factor-1 knock-out mice.

BACKGROUND AND AIMS: Interferon regulatory factor-1 (IRF-1) is a transcription factor with antiviral, proinflammatory and tumor suppressor properties. We examined the role of IRF-1 in dextran sulfate sodium colitis, a murine model of inflammatory bowel disease, to determine if absence of the gene would protect against colitis. METHODS: C57BL/6J mice with a targeted disruption of IRF-1 and wild-type C57BL/6J controls received five 7-day cycles of 2% dextran sulfate sodium alternating with five 7-day cycles of water. Colonic tissue was formalin fixed for histological analysis and total RNA extracted for gene chip and SYBR green real-time polymerase chain reaction (PCR) analysis. RESULTS: Histological analysis revealed increased distortion of crypt architecture in the dextran sulfate sodium-treated, IRF-1 -/- animals as compared to dextran sulfate sodium-treated wild-type animals. Five of 15 dextran sulfate sodium-treated IRF-1 -/- mice, but only one of 14 dextran sulfate sodium-treated wild-type mice, developed colonic dysplasia. Microarray analysis comparing colonic gene expression in IRF-1 -/- and wild-type animals revealed decreased expression of caspases, genes involved in antigen presentation, and tumor suppressor genes in the IRF-1 -/- animals. Increased expression of genes involved in carcinogenesis and immunoglobulin and complement genes was also noted in the knock-out animals. CONCLUSIONS: Absence of IRF-1 is not protective in dextran sulfate sodium colitis.

Adenocarcinoma↗
PubMed2004

Modeling mental navigation in scenes with multiple objects.

Various lines of evidence indicate that animals process spatial information regarding object locations differently from spatial information regarding environmental boundaries or landmarks. Following Wang and Spelke's (2002) observation that spatial updating of egocentric representations appears to lie at the heart of many navigational tasks in many species, including humans, we postulate a neural circuit that can support this computation in parietal cortex, assuming that egocentric representations of multiple objects can be maintained in prefrontal cortex in spatial working memory (not simulated here). Our method is a generalization of an earlier model by Droulez and Berthoz (1991), with extensions to support observer rotation. We can thereby simulate perspective transformation of working memory representations of object coordinates based on an egomotion signal presumed to be generated via mental navigation. This biologically plausible transformation would allow a subject to recall the locations of previously viewed objects from novel viewpoints reached via imagined, discontinuous, or disoriented displacement. Finally, we discuss how this model can account for a wide range of experimental findings regarding memory for object locations, and we present several predictions made by the model.

Animals↗
PubMed2002

The effects of antiretroviral therapy on HIV-1 RNA loads in seminal plasma in HIV-positive patients with and without urethritis.

BACKGROUND: High seminal plasma HIV-1 RNA loads (SVL) have been reported during gonococcal, non-gonococcal and chlamydial urethritis in patients not taking antiretroviral therapy. OBJECTIVE: To examine if urethritis leads to increased SVL in HIV-positive patients taking antiretroviral therapy. METHODS: Men who had been taking therapy for at least 3 months were recruited: 24 had urethitis (PWU) and 16 were without urethritis (controls). At three visits, 1 week apart, blood plasma viral load (BVL) and SVL were assayed by quantitative polymerase chain reaction or the NASBA assay. RESULTS: Most subjects had undetectable SVL (18 PWU, 13 controls). Among those with undetectable BVL prior to first study visit, virus was undetectable in semen in 5/5 episodes of chlamydial urethritis, 6/7 episodes of non-gonococcal urethritis and 4/5 cases of gonococcal urethritis. Two PWU with undetectable BVL just prior to the first study visit had low to moderate SVL, which became undetectable by visit 2 following treatment. Of nine subjects with detectable SVL, eight had detectable BVL (3/3 controls and 5/6 PWU). Of these, 1/3 controls and 4/5 PWU (all with gonococcal urethritis) had poorly controlled BVL just prior to the first study visit. These four PWU had high SVL and one had higher levels in semen than in blood. This patient's SVL was reduced more than 20-fold following treatment for gonococcal urethritis. CONCLUSIONS: Effective antiretroviral therapy appeared to limit the effect of urethritis on SVL. When BVL was poorly controlled by antiretroviral therapy, high SVL occurred during gonococcal urethritis, increasing the potential risk of transmitting both wild type and drug resistant strains of HIV-1.

Adult↗
PubMed2002

Pathways to care in children at risk of attention-deficit hyperactivity disorder.

BACKGROUND: There is underdiagnosis of and low use of specialist services for attention-deficit hyperactivity disorder (ADHD). AIMS: To quantify the filters in the help-seeking pathway through primary care and to investigate factors influencing progress for children at risk of ADHD. METHOD: A total of 127 children (5-11 years old) with pervasive hyperactivity who passed each filter (primary care attendance and general practitioner (GP) recognition of disorder) were compared with those who had not. RESULTS: Primary care attendance was only associated with parental perception of the behaviour as problematic (OR 2.11; 95% CI 1.11-4.03). However, GP recognition was related to both parent and child factors - parental request for referral (OR 20.83; 95% CI 3.05-142.08) and conduct problems (OR 1.48; 95% CI 1.04-2.12). GP non-recognition was the main barrier in the pathway to care; following recognition, most children were referred. CONCLUSIONS: Parents can be regarded as the main gatekeepers for access to specialist services.

Attention Deficit Disorder with Hyperactivity↗
PubMedDate not supplied

Persistent blurred vision after blepharoplasty and ptosis repair.

BACKGROUND: Visual disturbance after upper (eyelid) blepharoplasty is a relatively common postoperative complaint. Recent ophthalmology literature has demonstrated alternations of corneal curvature after procedures that reposition the upper eyelid using corneal topography. Astigmatic changes induced by eyelid repositioning may be a cause of persistent blurred vision after upper eyelid procedures. This observation has not been reported in the facial plastic literature. OBJECTIVE: To determine the incidence of persistent visual disturbance after upper blepharoplasty. METHODS: A retrospective review of upper blepharoplasty by 1 facial plastic surgeon and 2 oculoplastic surgeons during the year 2000. Patient interviews were conducted via telephone. RESULTS: A total of 146 patients were identified, and 106 of them responded to the study request. Six patients (5.7%) had subjective visual acuity changes 1 year after upper blepharoplasty, and 4 of the 6 patients had combined blepharoplasty and ptosis repair. Three patients had worse vision, 2 had improved vision, and 1 was unable to wear rigid contact lenses because of fogging. CONCLUSIONS: Prior studies have shown that most patients have measurable astigmatic changes 3 months after blepharoplasty and ptosis repair. We found that only a small percentage of them have persistent subjective symptoms 1 year postoperatively. It is important for facial plastic surgeons to properly advise patients, especially those with combined procedures, that upper eyelid repositioning procedures may induce long-term vision changes. Patients may need to obtain new prescription spectacles and contact lenses postoperatively.

Astigmatism↗