Search PubMed⌕ Search

Biomedical subjects

D Abbott

Publications and source records attributed to D Abbott.

At least 37 records · Page 2Linked to original sources
PubMed1997

Characterization of dynamic 3-D PET imaging for functional brain mapping.

Methods for optimizing the acquisition, reconstruction and analysis of positron emission tomography (PET) images for functional brain mapping have been investigated. The scatter fraction and noise-equivalent count rate characteristics were measured for the ECAT 951/31R PET scanner operating in septa-extended two-dimensional (2-D) and septa-retracted three-dimensional (3-D) modes. The 3-D mode is shown to provide higher signal-to-noise images than the 2-D mode at specific activities less than 30 kBq/ml. To enable increased temporal resolution in dynamic 3-D PET activation studies, a parallel version of the 3-D reconstruction algorithm was developed. Implementation of the reprojection algorithm on an 88 processor 1860 supercomputer resulted in a more than tenfold increase in reconstruction speed compared to a single 1860 processor system. An investigation of the optimal duration for imaging brain activations was undertaken in 12 normal subjects using repeated H2(15)O slow infusions and a visually presented lexical decision task. The significance of change in regional cerebral blood flow (CBF) was determined using statistical parametric maps for images acquired during stimulation, immediately after stimulation, and commencing 1 min after cessation of the stimulus. Regions of CBF change were detected in all three images. Dynamic 3-D, or four-dimensional (4-D), PET activation scanning is shown to be practical and likely to further improve the sensitivity of PET for detection of subtle regional CBF changes in functional brain mapping research.

Adult↗
PubMed1997

GAX collagen in the treatment of urinary incontinence in elderly women: a two year follow up.

OBJECTIVE: To determine the efficacy of GAX collagen in the treatment of elderly women with genuine stress incontinence. DESIGN: A single centre prospective study. SETTING: A London teaching hospital. PARTICIPANTS: Thirty-four women older than 60 years of age with genuine stress incontinence diagnosed on videocystourethrography. INTERVENTIONS: Up to three paraurethral injections of GAX collagen. MAIN OUTCOME MEASURES: Subjective and pad test assessments performed pre-operatively, after one month, one year and two years after the first injection of collagen. Videocystourethrography and urethral pressure profilometry were carried out pre-operatively, after three months and one year. RESULTS: There was a reduction in urinary leakage as measured on pad testing. After two years 77% of the surviving 26 women were symptomatically cured. Objectively after two years 48% of the women were cured and 9% were improved over their initial pre-treatment level of incontinence. The cure rate was the same whether or not the women had undergone previous vaginal surgery. The maximum urethral closure pressure was not increased with treatment indicating that collagen injections do not act by producing obstruction, but this should be interpreted with caution due to the small sample size. CONCLUSION: GAX collagen is an effective method of treating urinary incontinence in the elderly and especially women who have undergone previous continence procedures. The technique is easy to perform and particularly suitable in those who are frail, but if failure occurs after two years consideration needs to be given to its cost effectiveness.

Aged↗
PubMed1997

A complex arrangement of genes at a starch branching enzyme I locus in the D-genome donor of wheat.

Genomic DNA fragments from Triticum tauschii (D-genome donor to wheat) carrying starch branching enzyme I (SBE I) type genes have been characterized. One fragment contains one complete gene and two partial genes in 16 kb of DNA. One of the partial genes is oriented in the opposite strand to the other two. The gene that is complete was sequenced. Its structure corresponds closely to that of rice in that exons 3-8 are retained at similar sizes and spacings. A cDNA closely corresponding to the complete gene was isolated and characterized; it codes for a putative protein that represents a novel type of SBE I, as it is shorter at the 3' end than the forms reported so far in other plants. A second genomic fragment contains a different SBE I gene. There appear to be approximately 10 copies of SBE I type genes in wheat (approximately 5 in T. tauschii) and most of them have been assigned to group 7 chromosomes. In situ hybridization indicates that a major locus for the genes is located at the distal end of the short arm of chromosome 7D.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1995

Self-measurement of blood pressure: issues related to the training of patients. Canadian Coalition for High Blood Pressure Prevention and Control.

For effective self-measurement of blood pressure, patients need to be able to obtain accurate and reproducible measurements. Criteria for measuring blood pressure have been well developed in research studies, and through the use of standardized training programs it has been established that nonmedically trained individuals can obtain valid measurements. These recommendations for blood pressure measurement were adapted to the self-measurement situation. Either manual sphygmomanometers or automated electronic devices can be used effectively. Although automated devices may be easier to use, the health care practitioner should ensure that any such device has been demonstrated to be accurate and reliable before its adoption. There are no reported programs available for training individuals in the use of self-measurement. A check-list has been developed for use by health care practitioners. It is estimated that proper training will usually take more than 20 mins. Since many health care practitioners do not use the recommended blood pressure measurement technique, there is also a need to develop programs to 'train the trainers'. Finally, individuals undertaking regular self-measurement should have their technique and the calibration of their instruments checked at regular intervals (six to 12 months).

Blood Pressure Determination↗
PubMed1995

Self-measurement of blood pressure: recommendations of the Canadian Coalition for High Blood Pressure Prevention and Control.

OBJECTIVE: To provide health care professionals with guidelines on the use of blood pressure self-measurement. METHODS: Recommendations were devised after consideration of expert reviews and guidelines, personal files, international standards documents, personal communication with investigators and the results of a MEDLINE search (1966-94) using the term 'blood pressure determination'. BENEFITS, HARMS, COSTS: Self-measurement of blood pressure can be used to detect white coat hypertension, monitor changes in blood pressure closely, more rapidly achieve desired blood pressure goals, increase adherence to antihypertensive therapy and improve patient self-reliance. However, self-measured blood pressure readings may be misleading because there is insufficient normative, prognostic and outcome data and because some patients may not take accurate measurements. The use of self-measurement of blood pressure has a relatively small direct cost and may result in an overall reduction in treatment costs. RECOMMENDATIONS: Self-measured blood pressure readings can be a valuable supplement to clinic (or office) blood pressure readings. However, self-measurement is appropriate neither for patients who are physically or mentally incapable of accurate assessment and interpretation of readings nor for those who do not want to participate. Patients who self-monitor blood pressure require careful training in blood pressure measurement and instruction on the recording and interpretation of blood pressure readings. Advice to patients using monitoring equipment must take into account the needs and abilities of the patient. Although only a few electronic devices for the self-measurement of blood pressure have met recommended performance standards, their use may be more appropriate for some patients and the training requirements fewer than if manual devices are used. VALIDATION: The guidelines of several expert groups were examined in the preparation of these recommendations. The recommendations were presented at the World Conference on Hypertension Control in 1995 and were reviewed by the parent societies of the Canadian Coalition for High Blood Pressure Prevention and Control.

Blood Pressure Determination↗
PubMed1994

A novel technique for measuring bladder wall thickness in women using transvaginal ultrasound.

A new technique of measuring bladder wall thickness using transvaginal ultrasound is described. Measurement of the bladder wall using ultrasound was found to have a good intra- and interobserver reproducibility. Measurements of the bladder wall thickness were altered if more than 50 ml of fluid was within the bladder. Forty-five women with urinary symptoms were recruited from the urodynamic clinic; those with urodynamically diagnosed detrusor instability were found to have significantly thicker bladder walls than women with urodynamically diagnosed genuine stress incontinence. Application of this technique may be useful in the diagnosis of detrusor instability.

Journal Article↗
PubMed1993

Drainage of subretinal fluid with the argon laser.

We performed 115 scleral-buckling procedures for primary rhegmatogenous retinal detachments in which the argon endolaser drained subretinal fluid. The laser was set at 0.80 to 1.25 W and 0.5 second; the endolaser probe was held adjacent to, but not touching, the choroid. The procedure was successful in 112 of 115 (97.0%) patients. When inadequate drainage occurred, the use of the penetrating diathermy tip was successful. The only major complications were subretinal hemorrhages that had migrated posterior to the buckle in two patients (1.70%), retinal perforation in one patient (0.87%), and retinal incarceration in one patient (0.87%). Laser drainage caused a slow, controlled drainage of subretinal fluid.

Body Fluids↗
PubMed1993

Father involvement in infant care: two longitudinal studies.

Data collected from two samples of fathers in separate longitudinal studies were compared. One sample consisted of 53 first-time fathers and the other of 69 multiple-time fathers. A post-test only time-series design was used for both studies, and both employed the same procedures and instruments. The studies examined role enactment of fathers with different child-caring experiences using role-theory concepts. Fathers' normative expectations, personal expectations, and personal learning about parenting were tested to determine if they were predictive of paternal role performance. The findings seem to indicate that the culture of fatherhood has changed more rapidly than the conduct of fatherhood.

Adult↗
PubMed1992

The assessment of bladder neck movement in postpartum women using perineal ultrasonography.

Twenty-three postpartum women underwent perineal ultrasonography to determine bladder neck position at rest, on Valsalva and during pelvic floor contraction. On Valsalva, significant descent of the bladder neck and apposition to the symphysis pubis occurred. During pelvic floor contraction, there was significant elevation of the bladder neck; however, in approximately one-third of cases no movement was demonstrated. The bladder neck was shown to move through the arc of a circle whose center is the inferior border of the symphysis pubis. Perineal ultrasound provides a simple, objective way of measuring bladder neck elevation during pelvic floor contraction. This may be a more appropriate means of determining treatment outcome, in women undergoing conservative treatment for genuine stress incontinence, than measures of vaginal squeeze pressure.

Journal Article↗
PubMed1992

The effects of isoproterenol on the isolated perfused rat heart.

In isolated hearts infused with up to 100 ug/ml isoproterenol (ISO), there was only a transient effect on the frequency of contraction, and no effect on buffer flow through the heart. Infusion of hearts with 40-60 or 70-100 ug/ml ISO produced an increase in the release of lactate dehydrogenase, but not creatine kinase. Microscopic examination of hearts revealed myocyte separation and cytoplasmic vacuolation, of similar severity, in both control and ISO infused hearts; there was no necrosis. The data from this experiment are consistent with the view that ISO has little or no direct toxic effect on the heart. Since ISO is cardiotoxic In vivo, it is reasonable to suppose that this toxicity is linked primarily to the pharmacological effects of the drug. However, our study does not exclude the possibility that under the stressed conditions prevailing in vivo following a challenge with ISO, the susceptibility of myocytes to a direct toxic effect of ISO may increase.

Animals↗
PubMed1989

Achievement in an alternative high school for emotionally/behaviorally disturbed students.

Some 1,300 alternative high schools have been established in the United States for dealing with the special education needs of emotionally and behaviorally disturbed youth. The present study investigated cognitive, academic, and psychosocial variables associated with success in an alternative high school for such youth. Results indicated that psychosocial variables (Family Pathology, Duration of Disturbance, and Age of Admission) were associated with success, whereas cognitive and academic variables were not. These results are interpreted in light of their implications for assessment and placement decisions, management by mental health and school professionals, and curriculum modifications necessary for success.

Achievement↗
PubMed1988

Transfusion-induced specific anti-factor XI inhibitor in a patient with previously unrecognized factor XI deficiency.

This article reports the rare occurrence and investigation of a specific anti-factor XI inhibitor that arose after fresh-frozen plasma infusion into a patient with previously unrecognized Factor XI deficiency. The IgG fraction of the patient's plasma that contained anti-Factor XI antibody was isolated by chromatography on DEAE-Affigel and concentrated. It was shown to exert inhibitory effect on purified Factor XI and XIa both in the activated and nonactivated partial thromboplastin time assay.

Aged↗