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Biomedical subjects

M Mulholland

Publications and source records attributed to M Mulholland.

At least 19 recordsLinked to original sources
PubMed2005

Classification of chondroitin sulfate A, chondroitin sulfate C, glucosamine hydrochloride and glucosamine 6 sulfate using chemometric techniques.

Chondroitin sulfate A, chondroitin sulfate C, glucosamine hydrochloride and glucosamine sulfate are natural products that are becoming increasingly popular in the treatment of arthritis. They belong to a class of compounds known as glycosaminoglycans (GAGs). They are available over the counter as nutritional supplements. However, increasing use has led to increasing scrutiny of the quality of products on the market. There is also interest in the pharmacological properties of these compounds. To facilitate this, there is a need for better qualitative and quantitative methods of analysis. This paper describes methods for achieving the qualitative identification of chondroitin sulfate A, chondroitin sulfate C, glucosamine hydrochloride or glucosamine sulfate. Fourier transform infrared spectroscopy coupled with a variety of chemometric methods successfully classified these compounds. Using soft independent modeling of class analogies (SIMCA), hierarchical cluster analysis (HCA) and principal components analysis (PCA) samples were classified as either chondroitin sulfate A, chondroitin sulfate C, glucosamine hydrochloride or glucosamine sulfate. This work also examined the discriminating ability of different sections of the spectrum. It was found that for the classification of these compounds that using the finger print region of the spectrum (below 2000 cm(-1)) gave the best discrimination.

Chondroitin Sulfates↗
PubMed2004

Comparison of equations describing band broadening in high-performance liquid chromatography.

Several models are well established that describe band broadening in gas and liquid chromatography, including those due to Van Deemter and Knox. Comparison of competing models is complicated if raw data are noisy or if the equations to be fitted to data contain many adjustable parameters. This paper describes a comparison of fitting the Van Deemter, Knox and other equations to low noise data gathered during the separation of propyl- and methylparaben by HPLC. Equations are compared using established statistical methods, including analysis of residuals, inference of parameter estimates and Akaikes Information Criterion for model identification. This work indicates that equations that account for non-linear band broadening at elevated mobile phase velocities are more successful at describing the relationship between height equivalent to a theoretical plate, H, and the velocity of the mobile phase, u.

Chromatography, High Pressure Liquid↗
PubMed2003

Optimisation for the separation of the oligosaccharide, sodium Pentosan Polysulfate by reverse polarity capillary zone electrophoresis using a central composite design.

The separation by reverse polarity capillary zone electrophoresis of the therapeutically developed sodium salt of Pentosan Polysulfate was optimised through the analysis of response surface methodologies, modeled using a central composite design. The optimisation investigated injection pressure, injection time and voltage and the effect of the conditions on retention times, peak areas, separation efficiency and the method sensitivity. The overall goal was to develop the most sensitive results with no decrease in separation efficiency. The following results were obtained: (1) retention times generally decreased as injection pressure, injection time and voltage increased, injection time having the least effect; (2) as expected peak areas increased as injection pressure and injection time increased but decreased as voltage increased; (3) separation efficiencies generally increased as injection pressure and injection time decreased, with voltage having almost no effect. For the optimum condition, the sample was introduced at the inlet vial at the cathode hydrodynamically, at optimal setting of 44 s at 35 mbar. The optimal voltage was -20 kV. In comparison with other methods, the optimum showed increased sensitivity, resolution and separation efficiency. Repeatability studies were performed on the optimum parameter conditions. Relative standard deviation values obtained were between 0.9 and 5.4%.

Carbohydrate Sequence↗
PubMed2003

The role of the cytoskeleton in capacitative calcium entry in myenteric glia.

Capacitative calcium entry (CCE) is the process by which intracellular calcium is replenished from the external milieu upon depletion of intracellular stores. CCE is thought to participate in chemotaxis, proliferation and cell signalling. A physical interaction between intracellular stores and the plasma membrane is postulated to regulate CCE. We hypothesized that cytoskeletal disruption alters this interaction, inhibiting CCE in enteric glia. Cultured myenteric glia from neonatal guinea-pigs were treated with cytochalasin D (10 micro mol L-1), a microfilament disrupting agent, nocodazole (20 micro mol L-1), a microtubule disrupting agent, or vehicle (dimethyl sulphoxide). Intracellular calcium changes were measured using fura-2 microfluorimetry. To evaluate the rate of cation re-entry, barium was substituted for calcium because barium is not sequestered internally. Cytochalasin D-treated glia had diminished CCE responses (57 +/- 3 nmol L-1) compared with controls (97 +/- 7 nmol L-1) as did nocodazole-treated glia (30 +/- 2 nmol L-1) vs controls (77 +/- 6 nmol L-1). The proportion of cells demonstrating CCE abolition was greater in the cytochalasin (50 +/- 8%) and nocodazole-treated (89 +/- 2%) groups compared with controls (21 +/- 2%, 40 +/- 9%, respectively). Cytochalasin D and nocodazole treatment diminished the rate of cation re-entry based on diminished barium entry in treated vs control cells. From this study, we conclude that disruption of cytoskeletal elements diminishes calcium influx essential to calcium store repletion in myenteric glia.

Animals↗
PubMed2002

Modelling and control of potable water chlorination.

The Umgeni Water Wiggins water treatment plant feeds the southern areas of Durban in South Africa and has a maximum treatment capacity of about 350 Ml/d. Two interconnected reservoirs at this facility hold treated water before it enters the distribution network. Because of the variable demand, the reservoir levels and residence times undergo considerable variation. This has a strong influence on the free chlorine concentration in the water leaving the reservoir, which should be 0.8 to 1.2 mg/l, to ensure an adequate disinfection potential within the network. This paper describes a model which accounts for the observed variations of chlorine concentration, and will form the basis of a predictive controller for the chlorine concentration in the outlet.

Chlorine Compounds↗
PubMed2002

Optimal operation of a potable water distribution network.

This paper presents an approach to an optimal operation of a potable water distribution network. The main control objective defined during the preliminary steps was to maximise the use of low-cost power, maintaining at the same time minimum emergency levels in all reservoirs. The combination of dynamic elements (e.g. reservoirs) and discrete elements (pumps, valves, routing) makes this a challenging predictive control and constrained optimisation problem, which is being solved by MINLP (Mixed Integer Non-linear Programming). Initial experimental results show the performance of this algorithm and its ability to control the water distribution process.

Engineering↗
PubMed2001

The levonorgestrel intra-uterine system: therapeutic application in family planning.

OBJECTIVE: To assess the non-contraceptive benefits of the levonorgestrel intra-uterine system 12 months following insertion in a family planning setting. DESIGN: Postal questionnaire survey. SETTING: Family planning clinics at the Ulster and Bangor Hospitals. SUBJECTS: Eighty-six consecutive subjects fitted with the levonorgestrel intra-uterine system. RESULTS: Response rate 87.3%. Outcome measured in terms of compliance, satisfaction and menstrual symptomatology. Reasons for insertion were as follows: 21.7% contraception only; 65.2% menorrhagia, 24.6% dysmenorrhoea and 1.4% premenstrual syndrome. Duration of menses was 8.25 days pre-insertion and 2.41 days at 12 months. Of the subjects, 59.4% experienced at least one hormonal side effect; 10.1% of systems were removed within 12 months. At 12 months 86.9% of women were satisfied and 9.8% of women planned to discontinue. CONCLUSION: The levonorgestrel intra-uterine system was acceptable to almost 80% of women after 12 months, with significant reduction in duration of menses. Family planning clinics are an ideal setting to implement the guidelines for the initial management of menorrhagia.

Adolescent↗
PubMed2000

Quantitative determination of isoflavones and coumestrol in soybean by column liquid chromatography.

Four different stationary phases and a variety of solvents in varying proportions were examined in this study. Daidzein, genistein, formononetin, biochanin A and coumestrol were separated within 24 min on a phenyl column with acetonitrile-water (33:67, v/v) as eluent. The proposed method showed an acceptable repeatability with a RSD of quantitation <6%. The mean recoveries of daidzein, genistein, formononetin, biochanin A and coumestrol from soybean ranged from 89 to 104%. The identity of the individual analytes was confirmed by LC-MS-MS. The four isoflavones and coumestrol were isolated from soybean by hydrolysis with acid and heat. Neutralization of the soybean samples prior to identification did not alter the concentration of daidzein and genistein in soybean.

Chromatography, Liquid↗
PubMed2000

Direct identification and quantitation of prednisone in the presence of overlapping hydrocortisone by liquid chromatography with electrospray and atmospheric-pressure chemical-ionisation mass spectrometry.

The paper describes the application of liquid chromatography interfaced to a triple quadrupole mass spectrometer utilising the multiple reaction monitoring (MRM) mode. The technique was shown to provide detection limits lower than 0.01% for the analysis of prednisone in the presence of hydrocortisone. Prednisone was mixed in concentrations from 0.500 to 0.0005 ppm (corresponding to 1% to 0.001% of the hydrocortisone concentration). These solutions were assayed using MRM observing the product ion transitions of 359.2-->147.1 and 359.2-->171.2 and was shown to be capable of detecting co-eluting impurities at concentrations of less than 0.001% of the major component. The assay of prednisone was shown to be linear over the range 0.500-0.0005 ppm with a correlation coefficient of 0.999 and a precision of 6.9% at the concentration of 0.005 ppm. The analysis was carried out using both atmospheric pressure chemical ionisation (APCI) and electrospray ionisation (ESI) as an interface. However, for these compounds APCI provided significantly more sensitive data compared to ESI.

Atmospheric Pressure↗
PubMed2000

Full and fractionated experimental designs for robustness testing in the high-performance liquid chromatographic analysis of codeine phosphate, pseudoephedrine hydrochloride and chlorpheniramine maleate in a pharmaceutical preparation.

This paper describes the testing of a saturated factorial design using a full factorial design. Saturated factorial designs are often used to test the robustness of high-performance liquid chromatography (HPLC) methods, however they are based on several assumptions. A full factorial design relies on fewer assumptions and hence could be used to evaluate the effectiveness of the saturated design. Both designs were used to test a gradient HPLC method for the assay of codeine phosphate, pseudoephedrine hydrochloride and chlorpheniramine maleate. Six HPLC conditions, including wavelength, mobile phase pH and ion pairing reagent concentration were tested using the saturated design. Three of these factors were selected for full evaluation using a full factorial design. The results showed that the main effects calculated by each design were comparable. However, the saturated design showed higher standard errors, probably due to the effects of changing several more factors. One interaction effect was indicated as a confounding effect by the saturated design and this was confirmed by the calculation of the same interaction effect using the full design. Overall the method was shown to be robust under the variety of HPLC conditions tested.

Chlorpheniramine↗
PubMed2000

Safety and long-term efficacy of transduodenal excision for tumors of the ampulla of Vater.

BACKGROUND: Ampullary tumors should be resected because of the high incidence of malignancy and the unreliability of preoperative endoscopic diagnosis. Controversy exists about whether to perform a transduodenal excision (TDE) or a pancreatoduodenectomy. This study evaluated the safety and long-term efficacy of TDE. METHODS: The records of 21 patients with a pathologic diagnosis of ampullary adenoma who underwent TDE were reviewed. Demographics, symptoms, pathologic findings, and outcomes were analyzed and long-term follow-up was ascertained. RESULTS: Twenty-one patients (mean age, 61 years) underwent TDE. Final pathology showed adenoma in all patients including 1 (5%) with invasive cancer, 2 (9%) with microinvasive cancer, 6 (28%) with high-grade dysplasia, and 1 (5%) with low-grade dysplasia. The overall survival was 85% (mean follow-up of 38 months). One of 3 late deaths was likely related to disease progression. Sixteen of the 18 remaining patients (89%) had no evidence of tumor recurrence. One benign ampullary recurrence was successfully treated endoscopically. One additional patient developed an ampullary cancer and underwent pancreatoduodenectomy. CONCLUSIONS: TDE of benign ampullary tumors, even those with varying grades of dysplasia, can be performed with acceptable morbidity and low rates of recurrence. Postoperative endoscopic surveillance is mandatory to identify recurrent tumors.

Adenoma↗
PubMed1997

Linearity and the limitations of least squares calibration.

The magnitude of errors that can arise in practice from the limitations of the least squares method of calibration is estimated. Data generated from y = xn (0.7 < or = n < or = 1.3 and 1 < or = x < or = 30, or < or = 60) was analysed by least squares regression. Each y-value was then presented to the linear model and an x-value predicted. The relative errors on small x-values reached 70% of the concentration value even when r2 exceeded 0.999. Estimates of the errors on each predicted x-value, determined from the standard errors of the slope and intercept failed to reveal large errors at small x-values. Reducing the range over which linear regression is performed improved the errors. Other data sets with a heteroscedastic error distribution show that linear regression by least squares can also lead to the rejection of methods that performed sufficiently well for their application. Heteroscedastic data may be treated by repeated measurements at the lower end of the range. Data from a validation of an HPLC method for isoflavones in legumes is used to show the errors in recovery when a check sample is presented to the instrument using a calibration which satisfies the linearity tests. It is recommended that both y- and relative x-residuals are inspected. It is proposed that over-reliance on linear calibration supported by r2 may make a major contribution to large, hitherto unexplained, inter-laboratory errors.

Calibration↗
PubMed1997

Multimodality staging optimizes resectability in patients with pancreatic and ampullary cancer.

Few patients with pancreatic cancer have resectable disease at the time of diagnosis, and a variety of nonsurgical techniques are available to provide effective palliation of jaundice and pain. Accurate preoperative staging is essential to identify patients with unresectable disease, thereby minimizing unnecessary surgery. Currently used diagnostic tests include contrast-enhanced computerized tomography (CT), visceral angiography, endoscopic ultrasound, and laparoscopy, but their utility remains controversial. To evaluate the accuracy of these various diagnostic tests, 30 consecutive patients with histologically proven pancreatic or ampullary adenocarcinoma treated between 1992 and 1996 were evaluated. All 30 patients had contrast-enhanced CT and laparoscopy, 22 patients (73%) had visceral angiography, and 16 patients (53%) had endoscopic ultrasound. Individual and combined predictive values of resectability and unresectability as well as the sensitivities and specificities were determined for all diagnostic tests and compared with intraoperative findings. When CT, visceral angiography, and laparoscopy were combined, the predictive values of resectability and unresectability were 75 and 90 per cent, respectively, with a sensitivity of 75 per cent and a specificity of 90 per cent. Therefore, the combined use of selected diagnostic tests proved more effective than any single diagnostic test for accurately staging patients with pancreatic head and ampullary cancers and should be considered to minimize unnecessary surgery.

Adenocarcinoma↗
PubMed1994

Urinary tract glycoprotein: distribution and antigenic specificity.

It has previously been demonstrated that the urinary tract contains a unique glycoprotein (GP1) that appears to serve a function in the clearance of pathogenic bacteria. We prepared a panel of monoclonal antibodies (mAbs) to human GP1 and examined its antigenic specificity and distribution in the human urinary tract. This was also observed in relation to another glycoprotein associated with infection, Tamm-Horsfall protein (THP), as well as to URO-5, a protein used in identifying the lower urinary tract. In enzyme-linked immunoadsorbent assays (ELISA), all of the GP1 mAbs reacted with GP1 prepared from both human urine and rabbit bladder mucosa. No immunoreactivity was observed with either THP mAbs or URO-5 mAbs. Western-blot analyses using GP1 mAbs with human urine GP1 preparations detected a single band of approximately 50-52 kDa. Human urinary tract tissues were also examined by immunohistochemical techniques using the GP1 mAbs, commercial THP, and URO-5 mAbs. In paraffin-embedded bladder sections, only GP1 mAbs reacted with the urothelium. Selective staining of distal collecting tubules, renal pelvis, and ureters was demonstrated for GP1 mAbs. Proximal convoluted tubules, loops of Henle, and Bowman's capsule failed to stain for GP1. In the same tissues, THP mAbs reacted with the thick and thin segments of medullary loops of nephrons (Henle's loops). URO-5 mAbs stained fresh frozen sections of bladder urothelium, distal collecting tubules, and portions of Henle's loops; however, they failed to stain paraffin-embedded tissue sections. These GP1 mAbs provide a new tool for biochemical and histochemical investigations of the mucin layer in both healthy and diseased urinary tract tissue.

Animals↗
PubMed1989

Personality types of women attending an STD clinic: correlation with keeping first review appointments.

One hundred and eighty new women patients attending a sexually transmitted disease (STD) clinic answered the Eysenck personality questionnaire (EPQ) which measures psychoticism, extraversion, neuroticism, and a tendency to "fake good". These personality scores were correlated with the patients' attendance or non-attendance for their first review appointments. The results showed that the mean psychoticism scale scores of the 41 non-attenders was significantly higher than that of the 139 who kept their first appointment. This relation was confirmed using point biserial correlations. The mean scores of non-attenders on the other three EPQ scales were not significantly different from those of attenders, and none of the correlations between the other EPQ scales and this behavioural criterion was significant. The psychoticism scale is tentatively recommended for identifying women patients who may need special counselling about the importance of keeping their first review appointment.

Adult↗