Search PubMed⌕ Search

Biomedical subjects

D O'Sullivan

Publications and source records attributed to D O'Sullivan.

At least 37 records · Page 2Linked to original sources
PubMed2000

Measurements comparing the initial stability of five designs of dental implants: a human cadaver study.

BACKGROUND: A number of different dental implant designs are currently in clinical use. A successful outcome of implant placement is thought, at least in part, to be due to the primary stability of an implant after placement. Few data are available for comparing the primary stability characteristics of different implant designs. PURPOSE: This investigation compared the primary stability of five types of endosseous dental implant of varying geometry and surface topography. MATERIALS AND METHODS: Comparison was made between a standard threaded commercially pure titanium implant (Nobel Biocare AB, Göteborg, Sweden), the Mark II self-tapping implant (Nobel Biocare AB, Göteborg, Sweden), the Mark IV tapered self-tapping implant (Nobel Biocare AB, Göteborg, Sweden), the Astra Tioblast (AstraTech AB, Mölndahl, Sweden), and the 3i Osseotite (3I [Implant Innovations Incorporated], Palm Beach, Florida, USA). Fifty-two fixtures were placed in the maxillary bone of nine unembalmed human cadavers. Implant stability as a function of peak insertion torque and resonance frequency values was recorded for each fixture site after placement. Removal torque was also measured 1-hour postinsertion. Assessment of bone quality at each site was made. RESULTS: All of the implants tested demonstrated good primary stability in type 2 and 3 bone. The Standard, Mark II, Osseotite, and Tioblast were less stable when placed into bone type 4. The Mark IV implants appeared to maintain a high primary stability even in Type 4 bone. CONCLUSION: When looking across all bone qualities, the Mark IV implant develops a significantly higher insertion torque than the Standard, Mark II, and Osseotite implant types, and a significantly higher resonance frequency value than the Standard implant, indicating a higher interfacial stiffness at the implant-bone interface.

Aged↗
PubMed2000

Investigation of the relationship between lysogeny and lysis of Lactococcus lactis in cheese using prophage-targeted PCR.

The ability of lactococcal strains to lyse (and release intracellular enzymes) during cheese manufacture can be a very desirable trait and has been associated with improvement in flavor and acceleration of cheese ripening. Using a laboratory-scale cheese manufacturing assay, the autolytic behavior of 31 strains of Lactococcus lactis was assessed. In general, marked variation was observed between strains with a 20-fold difference between the best and worst lysing strains based on the release of the intracellular enzyme lactate dehydrogenase. In a parallel experiment, the genomes of these strains were examined for the presence of prophage integrase (int) sequences by using conserved primer sequences from known lysogenic phage. Results demonstrated that the lytic behavior of lactococcal starter strains significantly correlates with the presence of prophage sequences. These results highlight not only the contribution of prophage to starter cell lysis but also the potential of PCR as a useful initial screen to assess strains for this important industrial trait.

Cheese↗
PubMed2000

Catabolism of arginine and ornithine in the perfused rat liver: effect of dietary protein and of glucagon.

The rates of oxidation of arginine and ornithine that occurred through a reaction pathway involving the enzyme ornithine aminotransferase (EC 2.6.1.13) were determined using (14)C-labeled amino acids in the isolated nonrecirculating perfused rat liver. At physiological concentrations of these amino acids, their catabolism is subject to chronic regulation by the level of protein consumed in the diet. (14)CO(2) production from [U-(14)C]ornithine (0.1 mM) and from [U-(14)C]arginine (0.2 mM) was increased about fourfold in livers from rats fed 60% casein diets for 3-4 days. The catabolism of arginine in the perfused rat liver, but not that of ornithine, is subject to acute regulation by glucagon (10(-7) M), which stimulated arginine catabolism by approximately 40%. Dibutyryl cAMP (0.1 mM) activated arginine catabolism to a similar extent. In retrograde perfusions, glucagon caused a twofold increase in the rate of arginine catabolism, suggesting an effect of glucagon on arginase in the perivenous cells.

Adaptation, Physiological↗
PubMed1999

Efficacy of live, attenuated, human rotavirus vaccine 89-12 in infants: a randomised placebo-controlled trial.

BACKGROUND: Rotavirus is the most common cause of severe, dehydrating diarrhoea in infants worldwide. We assessed the safety, immunogenicity, and efficacy of a live, oral human rotavirus vaccine, 89-12, in US children in a randomised, placebo-controlled, double-blind multicentre trial. METHODS: 215 healthy infants were enrolled, of whom 213 were given two doses of 89-12 (containing 1x10(5) plaque-forming units) or placebo, and 213 were followed up through one rotavirus season. The frequency of side-effects was compared for 7 days after each dose of vaccine. Immune responses to rotavirus were assessed by serum and stool IgA, and by serum 89-12 neutralising titres. The primary outcome variable (protection from rotavirus disease) was evaluated by comparing the frequencies of rotavirus gastroenteritis in an intention-to-treat analysis. FINDINGS: Adverse reactions were mild. Low-grade fever (> or = 38.1 degrees C) after the first dose was the only side-effect significantly more common in the vaccine group than in the placebo group (21 [19%] vs 5 [5%], p=0.001). An immune response to vaccine was detected in 94.4% of vaccinees. Rotavirus disease occurred in 18 of 107 placebo recipients and two of 108 vaccine recipients (vaccine efficacy 89.0% [95% CI 65.4-94.5]). Ten infants in the placebo group but none in the vaccine group were presented for medical care. INTERPRETATION: The 89-12 rotavirus vaccine was safe and immunogenic and provided a high degree of protection against rotavirus disease. Further investigations of this vaccine are needed to confirm these findings in other settings.

Administration, Oral↗
PubMed1999

Cosmic rays and dosimetry at aviation altitudes.

Recent concerns regarding the effects of the cosmic radiation field at aircraft altitudes on aircrew have resulted in a renewed interest in detailed measurements of the neutral and charged particle components in the atmosphere. CR-39 nuclear track detectors have been employed on a number of subsonic and supersonic aircraft to measure charge spectra and LET spectra at aircraft altitudes. These detectors are ideal for long term exposures required for these studies and their passive nature makes them suitable for an environment where interference with flight instrumentation could be a problem. We report here on measurements and analysis of short range tracks which were produced by high LET particles generated mainly by neutron interactions at aviation altitudes. In order to test the overall validity of the technique measurements were also carried out at the CERN-CEC field which simulates the radiation field at aviation altitudes and good agreement was found with dose values obtained using mainly heavy ion calibration.

Aircraft↗
PubMed1999

Active monitoring of 12,760 clozapine recipients in the UK and Ireland. Beyond pharmacovigilance.

BACKGROUND: People prescribed clozapine for treatment-resistant schizophrenia have mandatory haematological monitoring through a case register for identifying reversible neutropenia. AIMS: To quantify risk factors for agranulocytosis in subjects receiving clozapine. METHOD: Data from 12,760 subjects registered to receive clozapine from January 1990 to April 1997 were analysed. Risk factors for agranulocytosis were quantified using a Cox proportional-hazards regression analysis. RESULTS: The risk for agranulocytosis in Asian subjects was 2.4 times that in Caucasians (P = 0.03). There was an age-related increase in risk of 53% per decade (P = 0.0001). CONCLUSIONS: The case register yielded valuable information for guiding research into the causes of the haematological reactions.

Adolescent↗
PubMed1999

Tuberculosis among homeless people in London: an effective model of screening and treatment.

SETTING: Hostels and day centres for homeless people in south London. OBJECTIVE: To develop an appropriate and effective method of screening for pulmonary tuberculosis (TB) among the homeless. DESIGN: Observational study evaluated for acceptability, yield of cases and completion of treatment. The screening included a symptom questionnaire, a Heaf test and a chest X-ray, developed and read on site. RESULTS: Ten clients (0.5%) were identified as having active pulmonary TB; seven of these were white men over the age of 50. The symptom questionnaire was seldom helpful. Nine of the cases were initially identified by chest X-ray, however only three of the 10 had a Heaf test performed. Eight of the 10 clients with active TB completed therapy; five additional clients were started on chemoprophylaxis. All of these had strongly positive Heaf reactions and normal chest X-rays. CONCLUSIONS: Chest X-ray screening is the most useful screening method and is effective if it is targeted. The use of incentives seems to increase the uptake of screening. Heaf testing is useful for the identification of those clients needing prophylactic treatment or BCG immunisation. Good compliance can be achieved provided clients are case managed appropriately.

Adult↗
PubMed1998

Variation in genome organization of the plant pathogenic fungus Colletotrichum lindemuthianum.

The genome structure of Colletotrichum lindemuthianum in a set of diverse isolates was investigated using a combination of physical and molecular approaches. Flow cytometric measurement of genome size revealed significant variation between strains, with the smallest genome representing 59% of the largest. Southern-blot profiles of a cloned fungal telomere revealed a total chromosome number varying from 9 to 12. Chromosome separations using pulsed-field gel electrophoresis (PFGE) showed that these chromosomes belong to two distinct size classes: a variable number of small (< 2.5 Mb) polymorphic chromosomes and a set of unresolved chromosomes larger than 7 Mb. Two dispersed repeat elements were shown to cluster on distinct polymorphic minichromosomes. Single-copy flanking sequences from these repeat-containing clones specifically marked distinct small chromosomes. These markers were absent in some strains, indicating that part of the observed variability in genome organization may be explained by the presence or absence, in a given strain, of dispensable genomic regions and/or chromosomes.

Ascomycota↗
PubMed1998

Design of a phage-insensitive lactococcal dairy starter via sequential transfer of naturally occurring conjugative plasmids

The plasmid-free Lactococcus lactis subsp. cremoris MG1614 is highly phage sensitive and lacks lactose fermenting ability (Lac) and primary casein degrading ability (Prt). Food grade gene transfer systems were used to sequentially superimpose different phage defense systems on this background, resulting in a gradual increase in resistance to bacteriophage in the derivatives. pLP712, encoding Lac and Prt, was then transferred to one of these hosts, into which plasmids encoding adsorption inhibition, restriction modification, and abortive infection had already been introduced. This resulted in a phage-resistant strain which was successfully used as a single-strain starter for cheddar cheese manufacture under industrial conditions.

Journal Article↗
PubMed1998

A deficiency in aspartate biosynthesis in Lactococcus lactis subsp. lactis C2 causes slow milk coagulation.

A mutant of fast milk-coagulating (Fmc+) Lactococcus lactis subsp. lactis C2, designated L. lactis KB4, was identified. Although possessing the known components essential for utilizing casein as a nitrogen source, which include functional proteinase (PrtP) activity and oligopeptide, di- and tripeptide, and amino acid transport systems, KB4 exhibited a slow milk coagulation (Fmc-) phenotype. When the amino acid requirements of L. lactis C2 were compared with those of KB4 by use of a chemically defined medium, it was found that KB4 was unable to grow in the absence of aspartic acid. This aspartic acid requirement could also be met by aspartate-containing peptides. The addition of aspartic acid to milk restored the Fmc+ phenotype of KB4. KB4 was found to be defective in pyruvate carboxylase and thus was deficient in the ability to form oxaloacetate and hence aspartic acid from pyruvate and carbon dioxide. The results suggest that when lactococci are propagated in milk, aspartate derived from casein is unable to meet fully the nutritional demands of the lactococci, and they become dependent upon aspartate biosynthesis.

Animals↗
PubMed1997

Audit of the implementation of selective neonatal BCG immunisation in south east London.

The implementation of a selective neonatal BCG immunisation policy adopted in south east London boroughs of Lambeth, Southwark, and Lewisham in 1992 has been audited. A survey conducted 18 months after the policy was implemented showed that only 11% of infants identified as eligible for neonatal BCG immunisation had been immunised. The results of the survey were fed back to neonatal units, which were encouraged to improve access to BCG immunisations for eligible infants. A second survey 17 months later showed that 14% of eligible infants had been immunised. Difficulties in applying complex selection criteria, rapid turnover of trained staff in acute units, and short neonatal stay were thought to contribute to the poor uptake of the selective programme delivered in the neonatal units. A community based BCG immunisation service has been commissioned to improve uptake.

BCG Vaccine↗
PubMed1997

Safety of oral terbinafine: results of a postmarketing surveillance study in 25,884 patients.

OBJECTIVE: To broaden the safety database for oral terbinafine by determining the incidence of adverse events, particularly rare risks, that accompany its uncontrolled use in actual clinical practice. DESIGN: Four open, prospective, uncontrolled, postmarketing surveillance studies were conducted in unselected patients in 4 countries. No exclusion criteria were applied. The only treatment instructions participating physicians received were the manufacturer's product information. Physicians monitored patients for adverse events at baseline, during treatment, and at the end of treatment. Serious events were identified according to study protocol, which was consistent for all 4 studies, allowing data to be pooled and analyzed collectively. SETTING: Patients were recruited from dermatology, general, and family practices in the United Kingdom, the Netherlands, Germany, and Austria. PATIENTS: Of the 25884 patients who entered the study, 38.6% had concomitant diseases, 42.8% were taking other medications, and 22.7% were older than 60 years. The predominant indication for terbinafine treatment was onychomycosis (72.2%). INTERVENTIONS: Data on treatment duration was available for 25091 patients. Median duration of treatment was 12 weeks (mean, 13.2 weeks). Treatment extended beyond 6 weeks in 76.0% of patients and for at least 12 weeks in 59.3%. MAIN OUTCOME MEASURES: The incidence of adverse events as reported by physicians, with their opinions regarding relationship to terbinafine therapy. RESULTS: The incidence of adverse events was 10.5%; the majority involved the gastrointestinal system (4.9%) or skin (2.3%). These tended to be mild, transient, and reversible. Terbinafine was considered a possible or probable cause of 11 (0.04%) serious adverse events. No drug interactions were reported, even in patients taking oral antidiabetic agents, astemizole, terfenadine, or cimetidine hydrochloride. CONCLUSIONS: The positive safety profile established during controlled clinical trials of oral terbinafine extends to its uncontrolled use in clinical practice. No previously unrecognized risks were identified.

Adolescent↗
PubMed1997

Amperometric bienzymic sensor for aspartame.

An amperometric enzyme electrode for the determination of aspartame was developed by covalent immobilization of alcohol oxidase and alpha-chymotrypsin. A platinum based hydrogen peroxide electrode was used as the detector. Excellent sensitivity was obtained using batch, flow-through and flow injection methods with detection limits of 2 x 10(-7), 4 x 10(-7) and 10(-6) mol l-1, respectively. Different strategies for eliminating interfering compounds, including the introduction of an additional alcohol oxidase-catalase membrane and signal subtraction using an alcohol electrode, were employed. A recovery study on seven food samples was carried out and the results were satisfactory.

Aspartame↗
PubMed1997

Hospital leadership for quality: theory and practice: II. Quality performance evaluation.

Hospitals need excellent leadership to be efficient in the use of scarce stakeholder resources and to be effective in the competitive provision of services to multiple customers. This paper is the second report on a study conducted with cooperation of the executive team at a large government-funded hospital in Brisbane, Australia. The overall study focused on linking the leadership concepts and attributes of the members of the executive with an overall evaluation of quality practice in the hospital. The first paper reported the leadership results. This paper reports the quality practice and its links with leadership. The study revealed use of data, understanding of processes and the formation of supplier partnerships as the areas of hospital activity most limiting the ability to improve. Little impact of leadership attributes was found, contrary to studies conducted elsewhere. This may be due to the strong influence of different professional groups within the hospital, since domains of leadership influence largely coincided with these groups.

Attitude of Health Personnel↗
PubMed1997

Evaluation of Peru-15, a new live oral vaccine for cholera, in volunteers.

A new live oral cholera vaccine, Peru-15, was studied for safety, immunogenicity, and excretion in 2 groups of healthy volunteers. Twelve inpatient volunteers received freshly harvested vaccine in doses of either 10(7) or 10(9) cfu. Subsequently 50 outpatient volunteers received freeze-dried vaccine in doses of 10(8) or 10(9) cfu or placebo in a three-cell, double-masked, placebo-controlled trial. The strain was well tolerated at all dose levels, and it stimulated high levels of vibriocidal antibodies in most inpatient volunteers and in all outpatient volunteers. Although antitoxin responses were less frequent and of lower magnitude than the vibriocidal responses, antitoxin responses were seen in >60% of the outpatient volunteers. About 60% of the volunteers excreted the vaccine in their feces; however, fecal excretion did not correlate with serologic responses. It is concluded that Peru-15 is a safe and immunogenic oral vaccine for cholera.

Administration, Oral↗
PubMed1997

Digital radiographic imaging transfer: comparison with plain radiographs.

Advances in digital imaging and computer display technology have allowed development of clinical teleradiographic systems. There are limited data assessing the effectiveness of such systems when applied to urologic pathology. In an effort to appraise the effectiveness of teleradiology in identifying renal calculi, the accuracy of findings on transmitted radiographic images were compared with those made when viewing the actual plain film. Plain films (KUB) were obtained from 26 patients who presented to the radiology department to rule out urinary calculous disease. The films were digitalized by a radiograph scanner into ARCNEMA-2 file format, compressed by a NASA algorithm, and transferred via a 28.8-kbps modern over standard telephone lines to a remote section 25 miles away, where they were decompressed and viewed on a 1600 x 1200-pixel monitor. Two attending urologists and two endourologic fellows were randomized to read either the transmitted image or the original radiograph with minimal clinical history provided. Of the 26 plain radiographic films, 24 were correctly interpreted by the fellows and 25 by the attending physicians (92% and 96% accuracy, respectively) for a total accuracy of 94% with no statistical difference (p = 0.16). After compression, all but one of the digital images were transferred successfully. The attending physicians correctly interpreted 24 of the 25 digital images (96%), whereas the fellows were correct on 21 interpretations (84%), resulting in a total 90% accuracy with a significant difference between the groups (p < or = 0.04). Overall, no statistical difference between the interpretations of the plain film and the digital image was revealed (p = 0.21). Using available technology, KUB images can be transmitted to a remote site, and the location of a stone can be determined correctly. Higher accuracy is demonstrated by experienced surgeons.

Algorithms↗
PubMed1997

Ureteral anastomosis in the orthotopic ileal neobladder: comparison of 2 techniques.

PURPOSE: The functional results and complications of 2 different ureteroileal anastomoses were evaluated in patients with bladder cancer undergoing radical cystectomy and orthotopic ileal bladder substitution. MATERIALS AND METHODS: Between 1989 and 1995, 102 patients underwent creation of a low pressure neobladder. In the first 50 cases the ureteroileal anastomosis was created with a split-cuff nipple technique as an additional antireflux mechanism. In the next 52 cases the ureteroileal anastomoses were constructed via the direct end-to-side technique counting on the antireflux protection of the afferent tubular limb. RESULTS: Stenosis occurred in 7 of the 100 ureters (6 patients) treated with the split-cuff nipple technique and 7 of 104 treated with a direct end-to-side anastomosis. This complication occurred more commonly in the left ureter (11 of 14 patients). Reflux was noted at cystography in 10 cases with the split-cuff nipple method and 12 with end-to-side anastomoses, and was symptomatic in only 3 patients. Four ureteral strictures were treated successfully with primary open repair. Percutaneous dilation and stenting were performed for 8 ureteral strictures: 2 cases were successful, 3 failed and 3 are unresolved. CONCLUSIONS: We observed no differences between the antireflux split-cuff and end-to-side anastomoses with regard to stricture formation or ureteral reflux. Therefore, we do not believe that there is a need to create antireflux ureteral anastomoses due to the tubular afferent ileal segment and given that the reflux is asymptomatic in most patients. Strictures may be treated with percutaneous balloon dilation and stenting but open repair appeared to be more effective.

Anastomosis, Surgical↗