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Biomedical subjects

Michael O'Leary

Publications and source records attributed to Michael O'Leary.

5 recordsLinked to original sources
PubMed2003

Late genitourinary and gastrointestinal toxicity after magnetic resonance image-guided prostate brachytherapy with or without neoadjuvant external beam radiation therapy.

BACKGROUND: This study was designed to estimate the rates of late genitourinary (GU) and rectal toxicity after magnetic resonance image (MRI)-guided prostate brachytherapy exclusively or in conjunction with external beam radiation therapy (EBRT). METHODS: Between November 1997 and April 2002, 201 patients with category T1C prostate carcinoma (according to the 2002 American Joint Committee on Cancer staging criteria), prostate specific antigen levels < 10 ng/mL, and biopsy Gleason score 3 + 4 disease were treated with MRI-guided brachytherapy exclusively or in conjunction with EBRT. The MRI-guided technique was designed to spare the urethra based on delivery of the prescription dose to the peripheral zone exclusively. The Kaplan-Meier method was used to estimate rates of freedom from late GU and rectal toxicity. Comparisons were made using a log-rank test. RESULTS: At a median follow-up of 2.8 years (range, 0.5-5.0 years), the 4-year estimates of rectal bleeding requiring coagulation for patients who underwent implantation therapy, compared with patients who received combined-modality therapy, were 8% versus 30%, respectively (log-rank P value = 0.0001). Although erectile dysfunction was common (range, 82-93%), with the use of sildenafil citrate (Viagra), it was estimated that at least two-thirds of patients had erectile function comparable to or superior to baseline function, independent of whether they received monotherapy or combined-modality therapy (P = 0.46). The 4-year estimate of freedom from radiation cystitis was 100% versus 95% (P = 0.01) for patients who received monotherapy and patients who received combined-modality therapy, respectively. No urethral strictures were observed, and no patients underwent postimplantation transurethral resection of the prostate. CONCLUSIONS: In the current study, rectal bleeding after MRI-guided prostate brachymonotherapy was infrequent, and urethral and bladder toxicity is reported to be rare and may be attributed to the urethral-sparing technique of the MRI-guided approach.

Aged↗
PubMed2003

Estimating the Haemophilus influenzae type b (Hib) disease burden and the impact of Hib vaccine in Fiji.

AIMS: To estimate Haemophilus influenzae type b (Hib) disease burden in Fiji in children under the age of 5 years (under-5s) prior to vaccine introduction. To compare estimates from WHO's Hib rapid assessment tool (RAT), with that from decline in disease after vaccine introduction. METHODS: Laboratory data (meningitis), hospitalization and mortality data (pneumonia and meningitis) before and after Hib vaccine introduction were collected. The RAT protocol provides two independent estimates of pre-vaccine disease burden (one based on meningitis incidence laboratory data and the other based on mortality statistics). A third estimate uses the decline in disease following vaccine introduction. RESULTS: The decline in meningitis hospitalizations implies a pre-vaccine Hib meningitis incidence of 66 per 100,000 in under-5s. This compares with a pre-vaccine RAT estimate of Hib meningitis incidence of 84 per 100,000 (for 1992-1993). The RAT estimated the total annual pre-vaccine Hib burden (meningitis plus pneumonia) at 476 cases and 36 deaths per year ("meningitis incidence method") and 70 cases and 5 deaths ("child mortality method"). Hib vaccine led to declines of 32% (95% confidence interval (CI)=11-48%), and 78% (95% CI=22-94%) for all under-5s meningitis hospitalizations and deaths, respectively. There was no similar consistent decline in pneumonia hospitalizations or deaths after vaccine introduction, except for a statistically significant reduction in pneumonia mortality in children aged under 1 year. CONCLUSIONS: Hib disease constitutes an important burden on the health of Pacific children that can be rapidly reduced with Hib vaccine. In this setting, routine morbidity statistics (comparing pre-and post-vaccine) provided an estimate of Hib meningitis burden which is broadly similar to that of the Hib RAT, suggesting that both might be valid ways to estimate Hib meningitis incidence. However, Hib pneumonia burden could not be estimated from routine statistics.

Animals↗
PubMed2003

Prevalence of sexually transmitted infections among antenatal women in Vanuatu, 1999-2000.

BACKGROUND: The epidemiology of sexually transmitted infections (STIs) and HIV in Vanuatu is poorly defined. GOAL: The goal was to determine the prevalence of laboratory-confirmed gonorrhea, chlamydia, trichomoniasis, syphilis seroreactivity, and HIV among pregnant women in Vila, Vanuatu. STUDY DESIGN: A cross-sectional survey of 547 pregnant women attending a first-visit antenatal hospital clinic in Vila. Laboratory testing included polymerase chain reaction on tampons for chlamydia, gonorrhea, and trichomoniasis; testing of sera for syphilis with rapid plasmid reagin; and enzyme-linked immunosorbent assay for HIV. RESULTS: The prevalence of trichomoniasis was 27.5% (150); of chlamydia, 21.5% (117); of gonorrhea, 5.9% (32); and of syphilis, 13 (2.4%). No HIV cases were detected; 214 women (40%) had > or =1 STI. Young age and single marital status were both significantly associated with infection (P < 0.001). CONCLUSION: Chlamydial infection and trichomoniasis are hyperendemic among pregnant women in Vila. Young, single women are at greatest risk for infection.

Adult↗
PubMed2003

Radiation exposure of normal temporal bone structures during stereotactically guided gamma knife surgery for vestibular schwannomas.

OBJECT: The dosimetry of radiation exposure of healthy inner, middle, and external ear structures that leads to hearing loss, tinnitus, facial weakness, dizziness, vertigo, and imbalance after gamma knife surgery (GKS) for vestibular schwannomas (VSs) is unknown. The authors quantified the dose of radiation received by these structures after GKS for VS to assess the likelihood that these doses contributed to postradiosurgery complications. METHODS: A retrospective study was performed using a prospectively acquired database of a consecutive series of 54 patients with VS who were treated with GKS during a 3.5-year period at an "open unit" gamma knife center. Point doses were measured for 18 healthy temporal bone structures in each patient, with the anatomical position of each sampling point confirmed by a fellowship-trained neurootologist. These values were compared against single-dose equivalents for the 5-year tolerance dose for a 5% risk of complications and the 5-year tolerance dose for a 50% risk of complications, which were calculated using known 2-Gy/fraction thresholds for chronic otitis, chondromalacia, and osseous necrosis, as well as the tumor margin dose and typical tumor margin prescription doses for patients in whom hearing preservation was attempted. External and middle ear doses were uniformly low. The intratemporal facial nerve is susceptible to unintentionally high radiation exposure at the fundus of the internal auditory canal, with higher than tumor margin doses detected in 26% of cases. In the cochlea, the basal turn near the modiolus and its inferior portion are most susceptible, with doses greater than 12 Gy detected in 10.8 and 14.8% of cases. In the vestibular labyrinth, the ampulated ends of the lateral and posterior semicircular canals are most susceptible, with doses greater than 12 Gy detected in 7.4 and 5.1% of cases. CONCLUSIONS: Doses delivered to middle and external ear structures are unlikely to contribute to post-GKS complications, but unexpectedly high doses may be delivered to sensitive areas of the intratemporal facial nerve and inner ear. Unintentional delivery of high doses to the stria vascularis, the sensory neuroepithelium of the inner ear organs and/or their ganglia, may play a role in the development of post-GKS tinnitus, hearing loss, dizziness, vertigo, and imbalance. Minimizing treatment complications post-GKS for VS requires precise dose planning conformality with the three-dimensional surface of the tumor.

Facial Nerve↗