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M J White

Publications and source records attributed to M J White.

At least 19 recordsLinked to original sources
PubMed2006

Parametric mapping of the hepatic perfusion index with gadolinium-enhanced volumetric MRI.

The purpose of this study was to adapt the hepatic perfusion index (HPI) methodology previously developed for MRI to derive 3D parametric maps of HPI, and to investigate apparent differences in HPI maps between a group of colorectal cancer patients and controls. To achieve this, a new and simpler approach to HPI calculation which does not require measurements from the aorta or portal vein is introduced, and assessed with large liver regions of interest (ROIs) in patients and controls. Several example HPI maps showing localized variation are then presented. The subject group consisted of 12 patients with known colorectal metastases, and 13 control subjects referred for routine contrast-enhanced spine imaging with no history of neoplastic disease. HPI was evaluated from serial T1 volume acquisitions acquired over the course of a Gd-DTPA bolus injection. Regions of abnormal perfusion were visible on the HPI maps derived for the patient group, manifested as areas of locally increased HPI extending around the visible margins of known metastases evident on the conventional contrast-enhanced images. This method for MR voxel-based parametric mapping of HPI has the potential to demonstrate regional variations in perfusion at the segmental and subsegmental level.

Adult↗
PubMed2006

Recent trends and developments in dialogue on radioactive waste management: experience from the UK.

This paper highlights some recent trends and developments in dialogue on radioactive waste management in the UK. In particular, it focuses on the use of dialogue around options for the management of risk, and describes techniques for stakeholder dialogue in the field of radioactive waste management. The paper summarises past and on-going experience in the UK, and provides an overview of some practical examples from decommissioning of the former reprocessing facility at Dounreay in Scotland. In common with developments and trend in other countries, the UK has moved to a position where there is now widespread recognition that radioactive waste management requires not only sound technical assessment of risk, but also public participation, consultation and stakeholder dialogue on proposed solutions and the associated risks. In fact, the shift of position has arguably been quite pronounced, with formal procedures to identify, clarify and integrate stakeholders' issues and concerns within the decision-making processes. Experience suggests that citizens are capable of engaging with complex technical issues such as radioactive waste. Indeed, the earlier in the decision-making process that public and stakeholder engagement (PSE) occurs--for example, on the consideration of options and alternatives--the greater the chance of reaching a successful outcome that properly reflects the values and opinions of stakeholders. In the UK, the assessment of alternative waste management options is increasingly being addressed through Best Practical Environmental Option (BPEO) studies. Responses to stakeholder engagement processes and experience of conducting BPEO studies emphasise that consultation must be open, transparent, deliberative and inclusive. However, while early consideration of generic approaches and option choices is necessary to generate a climate of openness and understanding, it remains essential to fully engage with local stakeholder and community groups to consider issues associated with proposed developments at a site-specific level. An interesting area where further attention may be warranted is the use in final decision-making of the results from participatory processes such as BPEO studies. Demonstrating clearly that participants' views have influenced decisions appears to be essential for retaining legitimacy and trust, confidence and goodwill.

Community Participation↗
PubMed2004

The influence of age on quality of life outcome in women following a tension-free vaginal tape procedure.

PURPOSE: Tension-free vaginal tape (TVT) has been introduced and demonstrated to be an effective treatment for stress urinary incontinence. Improved general health in the elderly population has led to a greater number of patients seeking surgical treatment for incontinence. We evaluated the impact of TVT on quality of life in elderly patients, defined as age 70 and older. MATERIALS AND METHODS: We prospectively evaluated 67 patients with genuine stress incontinence differentiated by age into 2 groups, namely 21 who were 70 years and older, and a control group of 46 younger than 70 years, with a validated questionnaire. We assessed quality of life changes following TVT for incontinence treatment. RESULTS: At the most recent followup quality of life scores improved significantly in the 2 groups (p <0.05). Stress incontinence improved significantly in the 2 groups (p <0.05). CONCLUSIONS: TVT is effective in each group. It is a viable treatment option to improve quality of life in older women with stress urinary incontinence.

Age Factors↗
PubMed2003

Interaction between muscle metaboreflex and mechanoreflex modulation of arterial baroreflex sensitivity in exercise.

The effect of external calf compression on baroreflex sensitivity (BRS) during electrically evoked plantar flexion and postexercise circulatory occlusion (PECO) was studied. Subjects took part in two experimental trials: control and compression. In both trials, electrically evoked isometric plantarflexion (Stim) was performed at 30% maximum voluntary contraction force for 2 min. During compression, a cuff (inflated to 250 mmHg) was applied to the active calf during exercise and PECO. Sequence analysis carried out on the systolic blood pressure responses, and R-wave-R-wave intervals revealed a rightward shift of the regression line along the pressure axis during Stim in both trials. In the control experiment, BRS was significantly (P < 0.01) increased from 10.37 +/- 1.87 ms/mmHg during Stim to 12.79 +/- 1.62 ms/mmHg during PECO. With external compression, BRS was unaltered between Stim (10.84 +/- 1.86 ms/mmHg) and PECO (11.40 +/- 1.54 ms/mmHg). Because the metabolic conditions were the same in both experiments, the results may best be explained by reactivation of muscle mechanoreceptor activity by external compression during PECO.

Adult↗
PubMed2001

Exercise-induced muscle chemoreflex modulation of spontaneous baroreflex sensitivity in man.

1. The goal of this study was to determine the effect of exercise-induced muscle chemoreflex activation on baroreflex sensitivity (BRS). This is a retrospective study using data obtained during two prior studies. 2. Twenty-three subjects with a mean (S.E.M.) age of 28 (1.5) years took part in the study. Sequence analysis was performed on the systolic blood pressure (SBP) responses, measured by a Finapres, and R-R intervals, measured from the ECG. 3. Electrically evoked isometric exercise (Stim) of the triceps surae was performed for 2 min at 30 % maximum voluntary contraction force. During exercise and for a further 2 min thereafter, circulation to the lower leg was occluded by inflation of a thigh cuff to above 200 mmHg. 4. Prior to exercise mean (+/- S.E.M.) BRS was 10.92 +/- 6.3 ms mmHg(-1), and BRS remained at this level during evoked exercise (10.90 +/- 7.1 ms mmHg(-1)). BRS increased to 12.34 +/- 6.0 ms mmHg(-1) during post-exercise circulatory occlusion (PECO) (P < 0.05, MANOVA, post hoc Student's paired t test vs. Stim) and fell to 9.27 +/- 4.4 ms mmHg(-1) during recovery (P < 0.01 vs. PECO value, P = 0.059 vs. resting value). 5. These data indicate that during PECO following electrically evoked plantar flexion, where only muscle chemosensitive afferents were likely to be stimulated, BRS was increased.

Adult↗
PubMed2001

Kinetics of the thiazolium ion-catalyzed benzoin condensation.

The formation of benzoin (Ph-CHOH-CO-Ph) from two molecules of benzaldehyde, catalyzed by 3-benzyl-5-(2-hydroxyethyl)-4-methylthiazolium bromide in methanol buffered with Et(3)N/Et(3)NH(+)Cl(-) has been studied. Initial-rate studies at various concentrations of PhCHO (0.1-1.7 M) showed that the reaction is close to being first order in PhCHO. Following the reaction in deuteriomethanol, (1)H NMR spectroscopy allowed rate constants for all three kinetically significant steps to be determined. These show that all three steps are partially rate-determining. A normal deuterium kinetic isotope effect for the overall reaction (k(H)/k(D) approximately 3.4) is observed using PhCDO, and a large inverse solvent isotope effect (k(D)/k(H) approximately 5.9) is observed using deuteriomethanol, consistent with the kinetic scheme presented here.

Journal Article↗
PubMed2001

Sarcoplasmic reticulum function and muscle contractile character following fatiguing exercise in humans.

1. This study examined the alterations in calcium release, calcium uptake and calcium ATPase activity of skeletal muscle sarcoplasmic reticulum in response to a bout of intense dynamic knee extensor exercise, and the relationship between these changes and alterations in muscle contractile characteristics in the human quadriceps. 2. In biopsy samples taken from the vastus lateralis, sarcoplasmic reticulum calcium release and calcium uptake were significantly depressed (P < 0.01 and 0.05, respectively) immediately following the exercise with no alteration in the sarcoplasmic reticulum Ca2+-ATPase activity. 3. A 33 % reduction in the maximum voluntary isometric torque was found following the exercise, with reduced torques from electrically evoked isometric contractions at low frequencies of stimulation (10 and 20 Hz) but not at higher frequencies (50 and 100 Hz). 4. The depressed calcium release was correlated (P < 0.05) with a decreased ratio of torques generated at 20:50 Hz, indicating an involvement in low frequency fatigue; however, no correlations between the muscle relaxation times or rates of change of torque and calcium uptake were observed.

Adult↗
PubMed2001

Is there a relationship between muscle fatigue resistance and cardiovascular responses to isometric exercise in mild chronic heart failure?

BACKGROUND: Exercise intolerance in chronic heart failure (CHF) may be due to altered fatigue resistance and muscle afferent input to the cardiovascular system from dysfunctional skeletal muscle. AIM: To determine whether calf muscle fatigue resistance was associated with the magnitude of a muscle afferent driven cardiovascular response to isometric exercise. METHODS AND RESULTS: Cardiovascular responses were recorded in eight stable CHF patients (ejection fraction 20-40%) and nine healthy, age-matched controls during voluntary and electrically evoked isometric plantar flexion and post-exercise circulatory occlusion. The force developed by the plantar flexors during a 2-min submaximal electrically evoked fatigue test was measured. There was no relationship between ischaemic muscle fatigue and cardiovascular changes during and after voluntary contraction in either group nor evoked contraction in the CHF group. In the control group, the change in diastolic blood pressure (DBP) at the end of evoked contraction was related to the severity of fatigue at 90 s and 120 s (FI=0.01DeltaDBP+0.3, r=0.81, P<0.05 and FI=0.02DeltaDBP+0.8, r=0.84, P<0.01, respectively). CONCLUSION: Muscle fatigue resistance did not relate to the magnitude of the cardiovascular stress generated by isometric exercise of the same muscle in these patients.

Blood Pressure↗
PubMed2001

Preexisting gastric carcinoid in a gastro-omental free flap.

The authors present a 72-year-old man with an extensive medical history including stage III squamous cell carcinoma of the right pyriform sinus diagnosed approximately 10 years before this report. They were asked to evaluate the patient for esophageal reconstruction after local radiation had led to benign stricture of his esophagus and subsequent development of a large, draining esophagocutaneous fistula. A gastro-omental free flap reconstruction of the esophagus and overlying skin defect was complicated by the intraoperative diagnosis of gastric carcinoid obtained from several polyps noticed on the gastric mucosa on routine inspection. This case report signifies the importance of close inspection of all free tissue transfers before interposition. Failure to do so could result in disastrous outcomes.

Aged↗
PubMed2001

Muscle afferent and central command contributions to the cardiovascular response to isometric exercise of postural muscle in patients with mild chronic heart failure.

The roles of muscle afferent activity and central drive in controlling the compromised cardiovascular system of patients with mild chronic heart failure (CHF) during isometric exercise were examined. Blood pressure and heart rate responses were recorded in eight stable CHF patients (ejection fraction 20-40%; age 62+/-11 years) and in nine healthy age-matched controls during voluntary and electrically evoked isometric plantar flexion and subsequent post-exercise circulatory occlusion (PECO). During voluntary contraction, control subjects had a greater mean increase in systolic blood pressure than patients (42.4+/-19.2 and 23.0+/-10.9 mmHg respectively; P<0.01), but this was not the case during PECO. During electrically evoked contraction, but not during PECO, the CHF group had smaller (P<0.05) mean increases in both systolic and diastolic blood pressure than controls (13.0+/-5.3 compared with 25.4+/-14.0 mmHg and 7.6+/-3.0 compared with 12.9+/-7.2 mmHg respectively). Intra-group comparison between responses to voluntary and electrically evoked contractions revealed greater (P<0.05) mean increases in systolic and diastolic blood pressure during the voluntary contraction in both the patients and the control subjects. These data suggest that muscle afferent drive to the pressor response from the triceps surae is low in this age group, both in control subjects and in CHF patients. Additionally, the patients may have a relatively desensitized muscle mechanoreceptor reflex.

Aged↗
PubMed2000

Underutilizers of mammography screening today: characteristics of women planning, undecided about, and not planning a mammogram.

Using concepts from the Precaution Adoption Process Model, we identified behavioral factors, sociodemographic and psychosocial variables, and beliefs about breast cancer that discriminated among women at different stages with regard to their intention to obtain mammography screening. An independent survey company conducted telephone interviews with 2,507 women aged 50 to 80 who were identified as underutilizers of mammography screening. Each underutilizer was assigned to one of three stages with regard to intention to get a mammogram: (a) definitely planning, (b) thinking about, and (c) not planning. Estimated actual risk of breast cancer, perceived risk to breast cancer, worry about breast cancer, and fear of learning from a mammogram that one has breast cancer were variables found to be significantly associated with intention to obtain a mammogram for several subgroups of underutilizing women. There are significant behavioral and psychosocial variables, beliefs and feelings about breast cancer, and demographic characteristics that distinguish underutilizing women at various stages with regard to intention to obtain mammography screening. Our findings provide new information that could help the health care professional motivate women who are not planning to utilize this preventive health measure to become regular utilizers.

Aged↗
PubMed2000

Promoting mammography: results of a randomized trial of telephone counseling and a medical practice intervention.

BACKGROUND: Despite widespread promotion of mammography screening, a distinct minority of women have remained underusers of this effective preventive measure. We sought to measure the effects of barrier-specific telephone counseling (BSTC) and a physician-based educational intervention (MD-ED) on mammography utilization among underusers of mammography screening. DESIGN: This was a randomized controlled trial. Women meeting criteria for mammography underuse at baseline (grouped by practice affiliation) were randomized to a reminder control condition (RC group received annual mailed reminders), BSTC or MD-ED interventions and followed for 3 years. Underuse was defined by failure to get two annual or biannual mammograms over a 2- to 4-year period prior to a baseline survey. PARTICIPANTS AND SETTING: The study included 1655 female underusers of mammography aged 50-80 years who were members of two health maintenance organizations (HMO) in central Massachusetts. INTERVENTIONS: BSTC consisted of periodic brief, scripted calls from trained counselors to women who had not had a mammogram in the preceding 15 months. Women could receive up to three annual calls during the study. MD-ED consisted of physician and office staff trainings aimed at improving counseling skills and office reminder systems. MAIN OUTCOME MEASURE: Self-report of mammography use during the study period was the main outcome measure. Regular use was defined as > or =1 mammogram every 24 months. RESULTS: Forty-four percent in each intervention group became regular users compared to 42% in the RC group. Among subjects who had prior but not recent mammograms at baseline, BSTC was effective (OR=1.48; 95% CI=1.04; 2. 10), and MD-ED marginally effective (OR=1.28; 95% CI=0.88, 1.85). Most recent users at baseline and few never users became regular users (61% and 17%, respectively) regardless of intervention status. CONCLUSIONS: Among mammography underusers BSTC modestly increases utilization for former users at a reasonable cost ($726 per additional regular user).

Aged↗
PubMed1999

Training-induced adaptations in the central command and peripheral reflex components of the pressor response to isometric exercise of the human triceps surae.

1. The effect of calf raise training of the dominant limb on the pressor response to isometric exercise of the triceps surae was examined in the trained dominant limb and the contralateral untrained limb. Blood pressure and heart rate responses to electrically evoked and voluntary exercise at 30 % maximum voluntary contraction (MVC), followed by post-exercise circulatory occlusion (PECO), were compared before and after a 6 week training period. 2. In the trained limb the diastolic blood pressure rise seen during electrically evoked exercise was reduced by 27 % after training. However, the response during PECO was not significantly affected. 3. During voluntary exercise of the trained limb, diastolic blood pressure rise was reduced by 28 %, and heart rate rise was significantly attenuated after training. During PECO no significant effects of training were observed. 4. Voluntary exercise of the untrained limb resulted in a 24 % reduction in diastolic blood pressure rise after the training period, and a significant attenuation of the heart rate increase during exercise. Responses to electrically evoked exercise and PECO of the untrained limb remained unaltered after training. 5. Attenuation of blood pressure and heart rate responses, in the contralateral untrained limb, during voluntary but not electrically evoked exercise, indicates a training-induced alteration in central command.

Adult↗
PubMed1999

The effectiveness of using standardized patients to improve community physician skills in mammography counseling and clinical breast exam.

BACKGROUND: Traditional didactic continuing education is relatively ineffective in improving physicians' clinical skills. We hypothesized that a centralized course including small group workshops utilizing standardized patients could improve clinical skills for a reasonable cost. METHODS: We designed a 5-h course aimed at improving physicians' counseling skills (re: screening mammography) and clinical breast exam (CBE) skills. The course included lectures, demonstrations, and small group skills sessions utilizing standardized patients and was offered to 156 typical community-based primary care physicians. Pre- and postcourse evaluation included in-office assessments of physician CBE and counseling performance by standardized patients and a written test of knowledge and attitudes. RESULTS: A total of 54.5% of eligible physicians participated. They improved modestly in only one of three areas of counseling skills measured (providing counseling appropriate to the patient's readiness to accept mammography, P = 0.01). The overall CBE score increased substantially from 24.8 to 34.7 (P < 0.0001). Knowledge in all areas measured and confidence in counseling patients also increased. The basic course cost $202 per physician trained. CONCLUSIONS: Most community-based primary care physicians may find small group training and in-office evaluation involving standardized patients acceptable. Such training may be more effective in improving physical exam skills than complex communication skills.

Breast Neoplasms↗
PubMed1999

The effects of athletic training and muscle contractile character on the pressor response to isometric exercise of the human triceps surae.

In this study, the influence of athletic training status and the contractile character of the active muscle on the magnitude of the pressor response (PR) to voluntary and electrically evoked isometric plantar flexion was investigated. Subjects were 10 sprint-trained athletes (sprint) (100-m, 200-m and 400-m) [mean (SD) age, 21 (2) years], 14 endurance trained athletes (distance) [22 (2) years] and 8 untrained men (control) [23 (3) years]. Twitch time to peak tension (TPT) in the sprint group [108 (7) ms] was significantly less (P<0.001) than that of the distance group [124 (10) ms]. During voluntary contraction, the mean change in systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (fc) was not significantly different between groups. During electrically evoked contractions, mean changes in SBP, DBP and fc were not significantly different between the sprint, distance and control groups. However, division of the sprint group into 400-m (sprint I) and 100/200-m athletes (sprint II) showed that an increase in DBP of 1.6 kPa (12 mm Hg) in sprint I was significantly less (P<0.05) than the 2.5 kPa (19 mm Hg) increase observed for both the distance and control groups. Prediction of the DBP response from our previously published relationship between TPT and DBP showed close agreement in all subject groups except sprint I; in these subjects the observed DBP response was only 55% of that predicted. Attenuation of the PR in the involuntary experiment suggests that some aspect of sprint training, but not endurance training, modifies the muscle afferent input to the PR in man.

Adult↗
PubMed1999

Transcription factors and their genes in higher plants functional domains, evolution and regulation.

A typical plant transcription factor contains, with few exceptions, a DNA-binding region, an oligomerization site, a transcription-regulation domain, and a nuclear localization signal. Most transcription factors exhibit only one type of DNA-binding and oligomerization domain, occasionally in multiple copies, but some contain two distinct types. DNA-binding regions are normally adjacent to or overlap with oligomerization sites, and their combined tertiary structure determines critical aspects of transcription factor activity. Pairs of nuclear localization signals exist in several transcription factors, and basic amino acid residues play essential roles in their function, a property also true for DNA-binding domains. Multigene families encode transcription factors, with members either dispersed in the genome or clustered on the same chromosome. Distribution and sequence analyses suggest that transcription factor families evolved via gene duplication, exon capture, translocation, and mutation. The expression of transcription factor genes in plants is regulated at transcriptional and post-transcriptional levels, while the activity of their protein products is modulated post-translationally. The purpose of this review is to describe the domain structure of plant transcription factors, and to relate this information to processes that control the synthesis and action of these proteins.

Amino Acid Sequence↗
PubMed1999

Childhood mortality and quality of care among abandoned children in nineteenth-century Italy.

A great deal of scholarly attention has been devoted in recent years to the large-scale abandonment of new born babies in the European past, with special emphasis given to the staggering rates of infant mortality among the foundlings. For the most part, scholars have agreed with the foundling home officials of the past in assigning much of the blame for this excess mortality to the women who took in the foundlings as wetnurses and subsequently as foster mothers. This article takes issue with this view, based on an examination of the children abandoned at the foundling home of Bologna, Italy in the nineteenth century. Four cohorts of foundlings are examined - those abandoned in 1809-30, 1829-30, 1849-50, and 1869-70 (N=3615) - as we trace the changing pattern of infant and early childhood mortality. Longitudinal methods are used in examining the life course of these foundlings and the determinants of their mortality.

Adoption↗