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Biomedical subjects

J Blundell

Publications and source records attributed to J Blundell.

At least 19 recordsLinked to original sources
PubMed2006

Medical optimisation can reduce morbidity and mortality associated with elective aortic aneurysm repair.

OBJECTIVES: Patients with aortic aneurysms have significant comorbidities which influence outcome. Our practice includes comprehensive assessment to identify comorbidities, allowing subsequent medical optimisation prior to aneurysm repair. The aim of this study was to assess this process and to identify any factors predictive of outcome. DESIGN: Prospective observational study. MATERIALS: Medical case notes of 200 patients referred with aortic pathology. METHODS: Data analysed included preoperative, perioperative and postoperative factors. Multiple logistic regression analysis was performed to identify predictors of outcome. RESULTS: Following assessment 17 patients (8.5%) were found to be unfit for intervention and 165 patients (82.5%) proceeded to aneurysm repair. In this group assessment uncovered previously undiagnosed cardiac, respiratory and renal comorbidity in 19%, 57% and 29% of patients respectively. Multiple logistic regression analysis indicated that optimisation by a renal physician reduced post-operative renal impairment (OR 0.12, 95% CI 0.03-0.45, P=0.002) while optimisation by a cardiologist reduced respiratory complications (OR 0.7, 95% CI 0.05-0.99, P=0.049). An abnormal echocardiogram was associated with pneumonia (OR 6.9, 95% CI 1.6-29, P=0.01) and death (OR 7.9, 95% CI 1.15-54, P=0.036). CONCLUSION: Pre-operative assessment identifies previously undiagnosed comorbidity in a significant proportion of patients. Subsequent medical optimisation may reduce post-operative morbidity and mortality.

Aged↗
PubMed2004

Binge-eating episodes are not characteristic of carriers of melanocortin-4 receptor gene mutations.

Recently, Branson and coworkers reported a strong association between binge-eating disorder (BED) and variants in the melanocortin-4 receptor gene (MC4R). In the current study, we compared the eating behavior of 43 obese probands with functionally relevant MC4R mutations and of 35 polymorphism carriers (V103I or I251L) with wild-type carriers. The module for eating disorders of the Composite International Diagnostic Interview was used to identify binge-eating behavior. The Three-Factor Eating Questionnaire and the Leeds Food Frequency Questionnaire were used to assess restrained eating, disinhibition, hunger and percent total energy intake as fat. No significant differences between carriers of MC4R variants and wild-type carriers were detected. In particular, we found no evidence for an increased rate of binge-eating behavior in obese carriers of MC4R variants. Our findings do not support the strong association between BED and MC4R carrier status.

Adolescent↗
PubMed2004

Rate and extent of compensatory changes in energy intake and expenditure in response to altered exercise and diet composition in humans.

We assessed the effect of no exercise (Nex; control) and high exercise level (Hex; approximately 4 MJ/day) and two dietary manipulations [a high-fat diet (HF; 50% of energy, 700 kJ/100 g) and low-fat diet (LF; 20% of energy, 300 kJ/100 g)] on compensatory changes in energy intake (EI) and energy expenditure (EE) over 7-day periods. Eight lean men were each studied four times in a 2 x 2 randomized design. EI was directly quantified by weight of food consumed. EE was assessed by heart rate (HR) monitoring. Body weight was measured daily. Mean daily EE was 17.6 and 11.5 MJ/day (P < 0.001) on the pooled Hex and Nex treatments, respectively. EI was higher on HF diets (13.4 MJ/day pooled) compared with the LF diets (9.0 MJ/day). Regression analysis showed that these energy imbalances induced significant compensatory changes in EB over time of approximately 0.3-0.4 MJ/day (P < 0.05). These were due to changes in both EI and EE in the opposite direction to the perturbation in energy balance. These changes were significant, small but persistent, amounting to approximately 0.2 and approximately 0.35 MJ/day for EI and EE, respectively.

Adaptation, Physiological↗
PubMed2003

Meso-portal bypass in children with portal vein thrombosis: rapid increase of the intrahepatic portal venous flow after direct portal hepatic reperfusion.

BACKGROUND/PURPOSE: In children with portal vein (PV) thrombosis, hepatopetal portal flow can be restored by an innovative surgical procedure, the meso-portal-bypass (MPB), if the umbilical portion of the intrahepatic left PV and the superior mesenteric vein are patent. This is associated with resolution of symptoms related to extrahepatic portal hypertension (EHPH). However, no data are available yet on intrahepatic hemodynamic changes after MPB. The aim of this study was to evaluate morphologic adaptation and flow characteristics of the intrahepatic PV branches (ihPVb) after MPB. METHODS: Prospective follow-up Doppler scans of the ihPVb were performed at 0.5 to 1, 3 to 6 and 12 months after MPB in 13 consecutive patients (2000-2002) and compared with preoperative findings. RESULTS: Only small ihPVb were detected preoperatively on Doppler in 8 of 13 cases. Postoperatively (median follow up 12; range, 6 to 24 months), all 13 patients had patent MPB with hepatopetal flow, and ihPVb were easy to detect with satisfactory vessel diameters and flow velocities. CONCLUSIONS: The preoperatively small ihPVb increase rapidly in diameter and hepatopetal flow velocity in patients benefiting from MPB. This correlates well with progressive resolution of their symptoms related to EHPH and reflects rapid adaptation of ihPVb.

Adolescent↗
PubMed2002

The effect of graded levels of exercise on energy intake and balance in free-living men, consuming their normal diet.

OBJECTIVE: To assess the effect of graded increases in exercised-induced energy expenditure (EE) on appetite, energy intake (EI), total daily EE and body weight in men living in their normal environment and consuming their usual diets. DESIGN: Within-subject, repeated measures design. Six men (mean (s.d.) age 31.0 (5.0) y; weight 75.1 (15.96) kg; height 1.79 (0.10) m; body mass index (BMI) 23.3(2.4) kg/m(2)), were each studied three times during a 9 day protocol, corresponding to prescriptions of no exercise, (control) (Nex; 0 MJ/day), medium exercise level (Mex; approximately 1.6 MJ/day) and high exercise level (Hex; approximately 3.2 MJ/day). On days 1-2 subjects were given a medium fat (MF) maintenance diet (1.6 x resting metabolic rate (RMR)). MEASUREMENTS: On days 3-9 subjects self-recorded dietary intake using a food diary and self-weighed intake. EE was assessed by continual heart rate monitoring, using the modified FLEX method. Subjects' HR (heart rate) was individually calibrated against submaximal VO(2) during incremental exercise tests at the beginning and end of each 9 day study period. Respiratory exchange was measured by indirect calorimetry. Subjects completed hourly hunger ratings during waking hours to record subjective sensations of hunger and appetite. Body weight was measured daily. RESULTS: EE amounted to 11.7, 12.9 and 16.8 MJ/day (F(2,10)=48.26; P<0.001 (s.e.d=0.55)) on the Nex, Mex and Hex treatments, respectively. The corresponding values for EI were 11.6, 11.8 and 11.8 MJ/day (F(2,10)=0.10; P=0.910 (s.e.d.=0.10)), respectively. There were no treatment effects on hunger, appetite or body weight, but there was evidence of weight loss on the Hex treatment. CONCLUSION: Increasing EE did not lead to compensation of EI over 7 days. However, total daily EE tended to decrease over time on the two exercise treatments. Lean men appear able to tolerate a considerable negative energy balance, induced by exercise, over 7 days without invoking compensatory increases in EI.

Adult↗
PubMed2001

Contrast-enhanced magnetic resonance angiography of the iliac arteries: optimization by injection simulation.

Protocols for contrast-enhanced magnetic resonance angiography (CE-MRA) of the iliac arteries were optimized by computer simulations based on an impulse response function (IRF) of contrast agent (CA) concentration as a function of time obtained for 20 patients. Protocols with sequential, centric, and elliptical k-space coverage, different repetition rates (5 and 10 ms), and CA doses (0.1, 0.2, and 0.3 mmol/kg b.w.) were compared in terms of signal-to-noise ratio (SNR), distortion of vessel profiles, and sensitivity to timing errors. IRF-based simulations successfully characterized CA recirculation. Slow-rate CA infusions were found to achieve relatively high enhancement. In terms of SNR, there is no advantage in increasing the repetition rate. Distortion of vessel profiles is more likely in elliptic and centric k-space coverage. Protocols based on sequential k-space coverage and relatively long CA infusions proved to be particularly suited to large-FOV iliac examinations as they are relatively insensitive to timing errors.

Adult↗
PubMed2001

Neural plasticity and stress induced changes in defense in the rat.

We investigated the effects of predator stress on behavior and amygdala afferent and efferent neural transmission in rats. Pathways studied were: ventral angular bundle input to the basolateral amygdala; central and basolateral amygdala output to the periaqueductal gray (PAG). Predator stress was 'anxiogenic' in elevated plus maze, light/dark box and acoustic startle tests one week after stress. Lasting changes were also observed in neural transmission. Predator stress appeared to potentiate right and depotentiate left hemisphere afferent amygdala transmission. In contrast, predator stress potentiated amygdala efferent transmission to right and left PAG, depending on the amygdala nucleus stimulated. Paired pulse and intensity series analysis suggests that transmission changes may be postsynaptic or presynaptic, depending on the pathway. Path analysis relating brain and behavioral changes suggests that potentiation and depotentiation in both hemispheres participate jointly in effecting some, but not all, of the behavioral changes produced by predator stress. Potentiation in left hemisphere amygdala afferents and efferents predicts anxiolytic-like effects, while potentiation in the right hemisphere amygdala afferents predicts anxiogenic-like effects. Path analysis also supports the view that changes in different neural systems mediate changes in different behaviors. These findings have their parallel in studies in the cat, but there are species differences.

Aggression↗
PubMed2000

The perceived position of the hand in space.

This paper reports a series of experiments of the perceived position of the hand in egocentric space. The experiments focused on the bias in the proprioceptively perceived position of the hand at a series of locations spanning the midline from left to right. Perceived position was tested in a matching paradigm, in which subjects indicated the perceived position of a target, which could have been either a visual stimulus or their own fingertip, by placing the index finger of the other hand in the corresponding location on the other side of a fixed surface. Both the constant error, or bias, and the variable error, or consistency of matching attempts, were measured. Experiment 1 showed that (1) there is a far-left advantage in matching tasks, such that errors in perceived position are significantly lower in extreme-left positions than in extreme-right positions, and (2) there is a strong hand-bias effect in the absence of vision, such that the perceived positions of the left and right index fingertips held in the same actual target position in fact differ significantly. Experiments 2 and 3 demonstrated that this hand-bias effect is genuinely due to errors in the perceived position of the matched hand, and not to the attempt at matching it with the other hand. These results suggest that there is no unifying representation of egocentric, proprioceptive space. Rather, separate representations appear to be maintained for each effector. The bias of these representations may reflect the motor function of that effector.

Adolescent↗
PubMed2000

The acute effect of D-tagatose on food intake in human subjects.

A double-blind randomized crossover study was performed with nineteen normal-weight men to investigate the effect on subsequent ad libitum food intake of replacing 29 g sucrose with 29 g D-tagatose as sweetener to a breakfast meal. D-Tagatose is a malabsorbed stereoisomer of fructose with potential application as a bulk sweetener. Food intake was measured at lunch offered 4 h after the breakfast meal, during the afternoon with access to abundant snacks, and finally at a supper buffet 9 h after the breakfast. Energy intake at lunch and during the snacking period was similar after ingesting the two sugars, while it was 15% lower after ingesting D-tagatose than with sucrose at supper (P < 0.05). Gastrointestinal factors such as the osmotic effects of unabsorbed D-tagatose causing distension of the gut might have mediated the acute appetite-suppressing effect. The present paper also refers to data from a preceding study in which we observed an increased self-reported energy intake after ingestion of D-tagatose compared with sucrose which, in fact, suggests a relative hyperphagic effect of D-tagatose. However, self-reported food intake may be biased by selective under-reporting and this subsequent study with a more controlled assessment of food intake was therefore conducted. This present study did not support any hyperphagic effect of D-tagatose, but rather suggests that D-tagatose may contribute to a reduced energy intake.

Adult↗
PubMed1998

Untangling the effects of hunger, anxiety, and nausea on energy intake during intravenous cholecystokinin octapeptide (CCK-8) infusion.

Infusions of cholecystokinin (CCK) may exert their effects on appetite by inducing feelings of nausea or anxiety. In this double blind, placebo controlled crossover study, the impact of these effects on appetite were examined. Fifteen male subjects received a 20 min i.v. infusion of cholecystokinin octapeptide (CCK-8) (4 ng/kg/min) or saline. The infusion commenced 20 min after a soup preload and 10 min before an ad libitum test meal. Visual analogue scales of appetite and mood were measured over 3 h, and subjects were instructed to report any other sensations they experienced over this time. CCK-8 significantly reduced premeal hunger, elevated premeal anxiety, and reduced energy intake at the ad libitum test meal. Meal duration and rate of eating (kcal/min) were also significantly reduced after CCK-8. After the smaller meal with CCK-8, hunger rose quickly to a higher level than with placebo. The return of hunger was commensurate with the smaller amount of energy consumed and indicated that CCK did not exert an enduring effect on hunger suppression. A significant correlation was found between the reduction in energy intake and hunger (r = 0.75 p < 0.01), but not with anxiety (r = 0.15 not significant). Analyses were performed separately on subjects who did (n = 8), or did not (n = 7) report gastrointestinal disturbance. Energy intake was reduced by 56.6% and 44.6%, respectively. These results indicate that, although feelings of anxiety and nausea may accompany CCK infusions, they are not necessary for the effects of CCK on appetite. These data provide support for a role of CCK in satiety.

Adolescent↗
PubMed1998

Are high-fat and low-fat consumers distinct phenotypes? Differences in the subjective and behavioural response to energy and nutrient challenges.

OBJECTIVE: To characterise the appetite control in habitual high fat (HF) and low fat (LF) phenotypes. DESIGN: Four treatment conditions for each subject group in a fully repeated 2 x 2 x 2 measures design. SETTING: The Human Appetite Research Unit at Leeds University, Psychology Department. SUBJECTS: Eight lean HF (mean % fat intake-46.7% daily energy) and eight lean LF (mean % fat intake - 29.9% daily energy) were recruited from the staff/student population of Leeds University. INTERVENTIONS: All subjects were provided with either a low (2129 kJ) or high (3801 kJ) energy meal at midday and the capacity for compensation was later measured by nutrient challenge (ad libitum consumption of either high fat or high CHO foods). Satiation and satiety were assessed by changes in energy and nutrient intakes, hunger, fullness and food preferences. RESULTS: The energy and nutrient manipulations gave rise to different levels in the rated intensity of hunger between HF and LF (P < 0.01). HF rated their baseline hunger at a higher level than LF, and the nutrient induced changes in hunger had a much greater amplitude. HF consumed significantly more energy from the high fat meals than from the high CHO meals (P < 0.05); this effect was not observed in LF. HF ate more energy and a greater weight of the high fat foods but less energy and smaller weight of the high CHO foods than did the LF. HF rated the high fat and high CHO foods equally satisfying, tasty and filling, whereas LF indicated a preference for high CHO foods (P < 0.05). CONCLUSIONS: The appetite control in habitual high and low fat consumers is different. HF 'passively overconsume' fat whereas this effect is weak in LF. The HF ate a constant weight of food whereas LF ate a more constant level of energy. HF could not distinguish between high and low fat foods suggesting that they were intrinsically insensitive or 'taste adapted' whereas LF were fat sensitive. The clear differences disclosed in response to signals generated by the characteristics of ingested food (weight, energy, nutrient composition, taste) suggest that habitual high and low fat consumers can be regarded as distinct behavioural phenotypes. The different styles of appetite control could arise from: (a) intrinsic physiological differences, or (b) a system which is adapted to deal with a particular type of diet.

Appetite↗
PubMed1998

Differences in energy expenditure and substrate oxidation between habitual high fat and low fat consumers (phenotypes).

OBJECTIVE: To investigate physiological differences between habitual high-fat (HF) and low-fat (LF) consumers, which could influence the balance between energy expenditure and energy intake, and the potential for weight gain. SUBJECTS: 16 young, lean males (eight HF and eight LF consumers; % energy from fat 44.3 and 32.0, respectively). MEASUREMENTS: Habitual dietary variables (from FFQ), body mass index (BMI), body fat % (measured by impedance), resting metabolic rate (RMR) (indirect calorimetry), substrate oxidation and basal heart rate, postprandial thermogenesis and heart rate in response to a high-fat (low carbohydrate (CHO)) and high-CHO (low fat) challenge. RESULTS: HF and LF (selected for their intake of fat) did not differ significantly in BMI or % body fat. HF had a significantly higher RMR (1624 vs 1455 kcal/d) and basal heart rate (66 vs 57 bpm) than LF. Differences in oxygen utilisation and heart rate were maintained over a 180 min period, following the high-fat and high-CHO challenge meals. HF had a significantly lower resting respiratory quotient (RQ) than LF and the differences in average RQ were significant over the 180 min examination period. HF had a significantly lower RQ response to the high fat (low CHO) than to the high CHO (low fat) challenge; this effect was not observed in LF. HF had higher total energy intake than LF and a higher absolute (but not %) intake of protein. CONCLUSION: Significant differences in basal energy expenditure and fat oxidation between habitual HF and LF consumers have been observed. The contributions of energy intake and protein intake (g not %) remain to be determined. In this particular group of subjects (young adult males) a high energy intake characterised by a large fat component is associated with metabolic adaptations which could offset the weight inducing properties of a high-fat diet. These physiological differences may be important when considering the relationship between dietary-fat and obesity.

Adolescent↗
PubMed1998

The high-fat phenotype: is leptin involved in the adaptive response to a high fat (high energy) diet?

OBJECTIVE: To investigate physiological differences which could influence the balance between energy expenditure and energy intake, between habitual high-fat (HF) and low-fat (LF) consumers and the potential for weight gain. SUBJECTS: Ten HF and nine LF consumers, all young, lean males (% energy from fat 45.4 and 31.8, respectively). MEASUREMENTS: Habitual dietary variables (from the food frequency questionnaire, FFQ), body mass index (BMI), % body fat (% BF, measured by impedance), fasting concentrations of plasma leptin, glucose and triglycerides. RESULTS: HF and LF subjects (selected for their fat intake) did not differ significantly in BMI or % BF. HF subjects had significantly higher concentrations of plasma leptin and lower concentrations of plasma glucose than LF subjects. In all subjects, concentrations of fasting plasma leptin correlated significantly with BMI, % BF and fat mass; difference in leptin between groups remained significant when BMI and % BF were used as covariants. Leptin significantly correlated with dietary variables; particularly dietary fat (% energy and g) and inversely with dietary carbohydrate (% energy), but showed no correlation with dietary protein or total energy intake. CONCLUSION: Significant differences in concentrations of fasting plasma leptin have been observed between lean male HF and LF consumers. These findings suggest that the difference in leptin concentrations could be associated with a metabolic adaptation which could help to offset the weight inducing properties of high fat (high energy) diets.

Adaptation, Physiological↗
PubMed1991

Pharmacological approaches to appetite suppression.

It is relatively easy to demonstrate drug-induced anorexia in animals, but the significance of-such suppression of eating is often doubtful. Of the many agents shown to be 'active' in animals, only a very few are genuine appetite suppressants with clinical potential. Drugs that increase central 5-HT levels, or that activate peripherally acting peptides, are currently among the most promising candidates. John Blundell advocates a systems approach to the study of appetite control. Drug-induced changes in feeding should be interpreted according to a system which involves behaviour, peripheral physiology and brain neural pathways. Appetite involves more than alterations of food intake; the concept should take into account changes in hunger, food preferences, responses to taste and changes in macronutrient preferences.

Animals↗
PubMed1985

Short-term culture of pediatric brain tumors.

Three short-term culture systems were applied to ten pediatric brain tumors and two samples each of normal child's brain and fetal brain. Growth in monolayer occurred in nine of the ten tumors but normal child's brain also produced cellular growth in these conditions. Six of nine tumors tested also formed colonies in suspension in semisolid or liquid conditions which did not permit the growth of normal glial cells. Astrocytomas and medulloblastomas have distinctive growth patterns both in monolayer and in suspension culture. Fetal brain from midtrimester abortions contained cells which, like tumor, formed colonies in suspension. The semisolid culture system was then used to test the sensitivity of brain tumor stem cells to drugs and radiation in vitro. Survival curves representative of our experience with the medulloblastomas and astrocytomas are presented. It is concluded that the system may have value in screening new agents for activity against children's brain tumors but because of the relative rarity of these diseases, a cooperative effort would be required to produce useful results.

Adolescent↗