Search PubMed⌕ Search

Biomedical subjects

J T Connor

Publications and source records attributed to J T Connor.

At least 19 recordsLinked to original sources
PubMed2005

Male sexual function improves after ileal pouch anal anastomosis.

PURPOSE: Restorative Proctocolectomy and Ileal Pouch Anal Anastomosis has become the gold standard surgical therapy for the majority of patients with mucosal ulcerative colitis. However sexual functional disturbances after this procedure can be a concern for patients. Therefore the aim of this study was to determine the outcome of sexual-function related quality of life in male patients undergoing restorative proctocolectomy. METHODS: One hundred and twenty-two male patients who underwent restorative proctocolectomy with ileal pouch anal anastomosis between 1995 and 2000 were evaluated by the validated International Index of Erectile Function (IIEF) scoring instrument. This index scale examines sexual function in five categories. These are erectile function, orgasmic function, sexual desire, intercourse satisfaction and overall satisfaction. The IIEF instrument was administered after surgery and then scores before and after RP/IPAA were evaluated and compared. The significance of age at the time of the surgery, type of surgery, type of anastomotic technique (mucosectomy vs stapled) and septic complications on sexual functional outcome were also investigated. RESULTS: Mean age at the time of the surgery was 39.9 +/- 11.5 years. The mean follow-up period (time between pouch surgery and IIEF completed) was 3.6 +/- 1.8 years. There was statistically significant improvement in 4 of 5 categories of sexual function (erectile function, sexual desire, intercourse satisfaction, and overall satisfaction) where patients had improved scores after surgery compared to prior to surgery. The mean erectile function score increased pre to post surgery by 2.12 points (P = 0.02), which indicates better sexual results. Anastomotic technique and septic complication did not influence the results, however, older age had a negative impact on results. CONCLUSIONS: Despite some adverse sexual functions, male patients who undergo RP/IPAA for the surgical management of their colitis may preserve or improve their overall sexual functional outcome.

Adult↗
PubMed2005

Human defensin 5 expression in intestinal metaplasia of the upper gastrointestinal tract.

BACKGROUND: Upper gastrointestinal tract intestinal metaplasia (IM) is termed Barrett's oesophagus (BO) or gastric intestinal metaplasia (GIM), depending on its location. BO and GIM are associated with chemical exposure resulting from gastro-oesophageal reflux and chronic Helicobacter pylori infection, respectively. Paneth cells (PCs), characterised by cytoplasmic eosinophilic granules, are found in a subset of IM at these sites, but histology may not accurately detect them. AIM: To determine human defensin 5 (HD5; an antimicrobial peptide produced by PCs) expression in BO and GIM, and to investigate its association with H pylori infection. METHODS: Endoscopic biopsies from 33 patients with BO and 51 with GIM, and control tissues, were examined by routine histology and for H pylori infection and HD5 mRNA and protein expression. RESULTS: In normal tissues, HD5 expression was specific for PCs in the small intestine. Five patients with BE and 42 with GIM expressed HD5, but few HD5 expressing cells in IM had the characteristic histological features of PCs. Most HD5 positive specimens were H pylori infected and most HD5 negative specimens were not infected. CONCLUSIONS: HD5 immunohistochemistry was often positive in IM when PCs were absent by conventional histology. Thus, HD5 immunohistochemistry may be superior to histology for identifying metaplastic PCs and distinguishing GIM from BO. The higher frequency of HD5 expression in GIM than in BO is associated with a higher frequency of H pylori infection, suggesting that in IM PCs may form part of the mucosal antibacterial response.

Adult↗
PubMed2004

Benefits of 'clean sweep' in Peutz-Jeghers patients.

OBJECTIVE: Laparotomy is the treatment of choice in Peutz-Jeghers Syndrome (PJS) patients for endoscopically irretrievable symptomatic polyps and polyp-related complications. During the last decade, we have operated on majority of the PJS patients with the purpose of removing all the gastrointestinal polyps (clean sweep), when an operation was indicated. The aim of this study is to evaluate the effect of clean sweep technique on the need for repeated surgery compared to a problem focused approach. PATIENTS AND METHODS: All patients with PJS treated in our institution since 1964 were studied. They were placed into two groups; those who had a problem-focused operation and those who were operated with the purpose of removing all small and large intestinal polyps. Demographics, presentation, follow-up period and the need for recurrent surgery were compared. RESULTS: We identified 11 patients (4 males, 7 females). Eight patients (5 females; median age 18.5) had problem-focused surgery for bleeding-anaemia (n = 3) or obstruction-intussusception (n = 5). These patients required 23 further operations within 87 patient-follow-up-years (2.64 operations per 10 years). Three patients (2 females; median age 6) were operated for bleeding-anaemia (n = 1) or obstruction-intussusception (n = 2) using the 'clean sweep' approach. These patients did not require any further surgery within 21 patient-follow-up-years. The gender, presentation and follow-up periods were similar between the groups. However, the 'clean sweep' technique appears to have reduced the need for further operations when it is compared with problem-focused approach (P = 0.01). CONCLUSION: To reduce the need for abdominal surgery and consequent problems in PJS patients, an attempt to remove all detected polyps (clean sweep technique) may be beneficial in these patients.

Adolescent↗
PubMed2003

The utility of the 13C-galactose breath test as a measure of liver function.

BACKGROUND: The 13C-galactose breath test has been reported to be an accurate, non-invasive method for the assessment of liver function. AIMS: To determine the optimal doses of labelled and unlabelled carrier galactose necessary to perform the 13C-galactose breath test, to assess the utility of the 13C-galactose breath test in distinguishing between normal subjects and those with liver cirrhosis and to determine whether the 13C-galactose breath test can stratify patients with cirrhosis based on their Child-Pugh score. METHODS: Twenty-three control subjects and 30 patients with liver cirrhosis received fixed doses of unlabelled carrier galactose and labelled 13C-galactose. Breath samples were collected just before and at 30-min intervals up to 4 h after the ingestion of unlabelled carrier galactose and labelled 13C-galactose. Each sample was analysed for its 13CO2 content. RESULTS: Doses of 25 g/m2 of unlabelled carrier galactose and 100 mg of 13C-galactose had the greatest sensitivity (93%; 95% confidence interval, 76-99%) and specificity (87%; 95% confidence interval, 65-97%) for distinguishing between normal subjects and cirrhotics when the test was performed 2 h after ingestion. The 13C-galactose breath test was also able to distinguish between class A and class B or C cirrhotics. CONCLUSION: The 13C-galactose breath test is a useful non-invasive tool for distinguishing between healthy subjects and patients with liver cirrhosis and between cirrhotics with well-compensated liver disease and those with decompensated liver disease.

Breath Tests↗
PubMed1998

Hybrid bilayer membranes in air and water: infrared spectroscopy and neutron reflectivity studies.

In this report we describe the fabrication and characterization of a phospholipid/alkanethiol hybrid bilayer membrane in air. The bilayer is formed by the interaction of phospholipid with the hydrophobic surface of a self-assembled alkanethiol monolayer on gold. We have characterized the resulting hybrid bilayer membrane in air using atomic force microscopy, spectroscopic ellipsometry, and reflection-absorption infrared spectroscopy. These analyses indicate that the phospholipid added is one monolayer thick, is continuous, and exhibits molecular order which is similar to that observed for phospholipid/phospholipid model membranes. The hybrid bilayer prepared in air has also been re-introduced to water and characterized using neutron reflectivity and impedance spectroscopy. Impedance data indicate that when moved from air to water, hybrid bilayers exhibit a dielectric constant and thickness that is essentially equivalent to hybrid bilayers prepared in situ by adding phospholipid vesicles to alkanethiol monolayers in water. Neutron scattering from these samples was collected out to a wave vector transfer of 0.25 A(-1), and provided a sensitivity to changes in total layer thickness on the order of 1-2 A. The data confirm that the acyl chain region of the phospholipid layer is consistent with that observed for phospholipid-phospholipid bilayers, but suggest greater hydration of the phospholipid headgroups of HBMs than has been reported in studies of lipid multilayers.

Lipid Bilayers↗
PubMed1997

A constrained neural network Kalman filter for price estimation in high frequency financial data.

In this paper we present a neural network extended Kalman filter for modeling noisy financial time series. The neural network is employed to estimate the nonlinear dynamics of the extended Kalman filter. Conditions for the neural network weight matrix are provided to guarantee the stability of the filter. The extended Kalman filter presented is designed to filter three types of noise commonly observed in financial data: process noise, measurement noise, and arrival noise. The erratic arrival of data (arrival noise) results in the neural network predictions being iterated into the future. Constraining the neural network to have a fixed point at the origin produces better iterated predictions and more stable results. The performance of constrained and unconstrained neural networks within the extended Kalman filter is demonstrated on "Quote" tick data from the $/DM exchange rate (1993-1995).

Algorithms↗
PubMed1997

Improved option pricing using artificial neural networks and bootstrap methods.

A hybrid neural network is used to predict the difference between the conventional option-pricing model and observed intraday option prices for stock index option futures. Confidence intervals derived with bootstrap methods are used in a trading strategy that only allows trades outside the estimated range of spurious model fits to be executed. Whilst hybrid neural network option pricing models can improve predictions they have bias. The hybrid option-pricing bias can be reduced with bootstrap methods. A modified bootstrap predictor is indexed by a parameter that allows the predictor to range from a pure bootstrap predictor, to a hybrid predictor, and finally the bagging predictor. The modified bootstrap predictor outperforms the hybrid and bagging predictors. Greatly improved performance was observed on the boundary of the training set and where only sparse training data exists. Finally, bootstrap bias estimates were studied.

Algorithms↗
PubMed1997

Cruel knives? Vivisection and biomedical research in Victorian English Canada.

This discussion shows how the use of animals in biomedical research in Canada evolved during the latter half of the nineteenth century from simple demonstrations to more sophisticated series of experiments. More important, however, is the argument advanced that Anglo-Canadian society's response to vivisection and the use of animals in research centred on issues such as cruelty, exploitation, and broader notions of religion, power, and gender. This exploration of vivisection in Victorian Canada, then, reveals that it was, as elsewhere, a complex debate involving more than the use of animals for biomedical research purposes.

Animal Welfare↗