Self-Practice Program for Beating-Heart Minimally Invasive Coronary Anastomosis Using a Homemade Low-Fidelity Simulator: A Proof of Concept

OBJECTIVE

We evaluated the effectiveness of a consistent and structured self-practice coronary anastomosis program using a homemade low-fidelity beating-heart simulator.

METHODS

An intermediary trainee was subjected to an 8-week structured self-practice program. The program was divided into 2 parts of nonbeating and beating practices with a minimum number of timed anastomoses. Each part was followed by an assessment using an objective skills assessment tool score. The beating-heart simulator was built using motorized toy blocks connected wirelessly to a smartphone application. This was coded to enable rate selection. A junior consultant was compared to the subject at the end of the program. Both were tasked to perform 1 coronary anastomosis for both off-pump coronary artery bypass (OPCAB) and minimally invasive CAB (MICS) setup. The primary outcomes were anastomotic time and score compared with the junior consultant. Secondary outcomes were progression of anastomotic time and score throughout the program.

RESULTS

Overall performance of the studied subject approached the performance of the junior consultant in terms of time (OPCAB, 489 vs 605 s; MICS, 712 vs 652 s) and scores (OPCAB, 21 vs 20.7; MICS, 19 vs 20.6). There were inverse correlations between anastomosis time and number of practices for both nonbeating and beating anastomoses. Overall improvement was observed in terms of assessment scoring by 26.6%.

CONCLUSIONS

A structured self-practice program using an affordable and accessible simulator was able to help trainees overcome the MICS anastomosis learning curve quicker when introduced earlier. This may encourage earlier adoption of MICS among surgeons.

Transit time flow measurement and outcome in coronary artery bypass grafting for surgeon and trainee

Background

Trainees need to operate under appropriate supervision to become competent. Transit time flow measurement (TTFM) is useful in detecting intraoperative graft failures during coronary artery bypass grafting (CABG). This study aims to compare the intra- and postoperative outcomes, including TTFM, of isolated CABG performed by a single consultant versus trainees and to determine the relationship between the pulsatility index (PI) and postoperative outcomes.

Methods

This retrospective study included 155 isolated CABG cases. Intraoperative outcomes included duration of cardiopulmonary bypass (CPB) and aortic cross-clamp and TTFM for arterial and venous grafts. Postoperative outcomes included common postoperative complications and mortality. The odds ratios of postoperative complications and mortality for arterial and venous grafts with PI ≤3 relative to grafts with PI >3 were determined with multiple logistic regression.

Results

The duration of CPB and aortic cross-clamp was significantly shorter in the consultant’s group. TTFM for both arterial and venous grafts were similar and no significant differences in postoperative complications and mortality were detected between the two groups. Patients with arterial grafts with PI ≤3 were less likely to require an intra-aortic balloon pump (IABP) or be ventilated for a prolonged period. No significant differences in postoperative outcomes and mortality were detected between venous grafts with PI ≤3 and PI >3.

Conclusions

Trainees can achieve good results in isolated CABG with appropriate case selection. Patients with arterial grafts with PI ≤3 have better postoperative outcomes.

Effect of Vessel Tortuosity on Stress Concentration at the Distal Stent-Vessel Interface: Possible Link With New Entry Formation Through Biomechanical Simulation

A computational approach is used to investigate potential risk factors for distal stent graft-induced new entry (dSINE) in aortic dissection (AD) patients. Patient-specific simulations were performed based on computed tomography images acquired from six AD patients (three dSINE and three non-dSINE) to analyze the correlation between anatomical characteristics and stress/strain distributions. Sensitivity analysis was carried out using idealized models to independently assess the effect of stent graft length, stent tortuosity and wedge apposition angle at the landing zone on key biomechanical variables. Mismatch of biomechanical properties between the stented and nonstented regions led to high stress at the distal stent graft-vessel interface in all patients, as well as shear strain in the neighboring region, which coincides with the location of tear formation. Stress was observed to increase with the increase of stent tortuosity (from 263 kPa at a tortuosity angle of 50 deg to 313 kPa at 30 deg). It was further amplified by stent graft landing at the inflection point of a curve. Malapposition of the stent graft led to an asymmetrical segment within the aorta, therefore changing the location and magnitude of the maximum von Mises stress substantially (up to +25.9% with a +25 deg change in the distal wedge apposition angle). In conclusion, stent tortuosity and wedge apposition angle serve as important risk predictors for dSINE formation in AD patients.

Comparison of diametric and volumetric changes in Stanford type B aortic dissection patients in assessing aortic remodeling post-stent graft treatment

Background

The study aims to analyze the correlation between the maximal diameter (both axial and orthogonal) and volume changes in the true (TL) and false lumens (FL) after stent-grafting for Stanford type B aortic dissection.

Method

Computed tomography angiography was performed on 13 type B aortic dissection patients before and after procedure, and at 6 and 12 months follow-up. The lumens were divided into three regions: the stented area (Region 1), distal to the stent graft to the celiac artery (Region 2), and between the celiac artery and the iliac bifurcation (Region 3). Changes in aortic morphology were quantified by the increase or decrease of diametric and volumetric percentages from baseline measurements.

Results

At Region 1, the TL diameter and volume increased (pre-treatment: volume =51.4±41.9 mL, maximal axial diameter =22.4±6.8 mm, maximal orthogonal diameter =21.6±7.2 mm; follow-up: volume =130.7±69.2 mL, maximal axial diameter =40.1±8.1 mm, maximal orthogonal diameter =31.9+2.6 mm, P<0.05 for all comparisons), while FL decreased (pre-treatment: volume =129.6±150.5 mL; maximal axial diameter =43.0±15.8 mm; maximal orthogonal diameter =28.3±12.6 mm; follow-up: volume =66.6±95.0 mL, maximal axial diameter =24.5±19.9 mm, maximal orthogonal diameter =16.9±13.7, P<0.05 for all comparisons). Due to the uniformity in size throughout the vessel, high concordance was observed between diametric and volumetric measurements in the stented region with 93% and 92% between maximal axial diameter and volume for the true/false lumens, and 90% and 92% between maximal orthogonal diameter and volume for the true/false lumens. Large discrepancies were observed between the different measurement methods at regions distal to the stent graft, with up to 46% differences between maximal orthogonal diameter and volume.

Conclusions

Volume measurement was shown to be a much more sensitive indicator in identifying lumen expansion/shrinkage at the distal stented region.

Analysis of Oil Palm Tree Recognition using Drone-Based Remote Sensing Images

The oil palm tree, or scientifically called as Elaeis guineensis is native to West Africa, where it grows in the wild, transformed into a crop that later was introduced to Malaysian industry. The cultivation of oil palm improved rapidly under the agricultural sector causes degradation, particularly when the oil palm plantation goes uncontrolled. Tree plantation identification is very important for plantation management, environmental management, biodiversity monitoring and many other applications. Accurate inventories and monitoring oil palm estates can be a challenge and critical towards the plantation management and plant area expansion. Managing oil palm estate manually can almost be impossible, so do the tree counting. Manual field-based tree counting is time-consuming and high cost. Conventional method for tree counting can be carried out by manually marked on images or carry out field surveying using GPS to collect the positions of oil palm trees and display their position on image. Developing easier, simpler and cheaper method for tree counting is needed. The aim of this study is to analyse oil palm trees using drone-based remote sensing images. The algorithms used in this research study including Gray-Level Co-occurrence Matrix (GLCM), wavelet transform and template matching. The database of oil palm tree been developed with a total of 131 oil palm trees and 161 of non-oil palm trees have been collected. The window size of oil palm tree been analysed where 250 x 250 pixels which GLCM showed the best overall accuracy of 73.10% for both oil palm and non-oil palm. In this specific window, the oil palm crown can be covered and the result given is more accurate compared to other window sizes. The resulting analysis shows that wavelet transform algorithm gives the highest overall accuracy value which is 82.07%. The other eight statistic parameters can also used to modify the GLCM in order to observe the accuracy and identify which give the best classification accuracy. The availability and ubiquity of drone technologies with high resolution images and regular basis monitoring, new techniques in image and pattern recognition using drone-based remote sensing images let the idea of high accuracy oil palm tree detection become a reality.

Obstructive sleep apnoea and open heart surgery: a review of its incidence and impact to patients

Background

Obstructive sleep apnea (OSA) is a serious health disorder which contributes to cardiovascular complications, decreased work productivity, automobile accidents, and death. This condition is characterized by a temporary cessation of breathing resulting due to upper airway closure during a person's sleep. Strain to the heart caused by this repetitive hypoxic insult can lead to postoperative complications for patients undergoing heart surgery. Recognizing cardiac surgical patients with OSA is important. Early recognition and intervention such as use of BiPAP device can reduce the postoperative complications due to OSA.

Methods

The aim of this study is to identify the incidence of unrecognized OSA in cardiac surgical patients. This is a retrospective analysis of a prospective data of the study which was done between July 2012 and July 2013 in University Malaya Medical Center. All patients undergoing elective cardiac surgery were recruited and the demographic data, questionnaire and the portable sleep study results were obtained. Patients were followed up till 30 days to record any complications. Data were entered in SPSS version 17 and analysis was done.

Results

The incidence of OSA was 61.4% and 43.5% were moderate to severe OSA. There was male predominance of OSA (79%) with a mean age of 60 years. OSA subjects had shorter inter-incisor distance (4.18±0.6 cm) and larger waistline (94.1±12.1 cm). The STOP-Bang questionnaire has a sensitivity of 75.8% in predicting apnoa-hypopnea index (AHI) ≥5/hour.

Conclusions

OSA can be diagnosed with a simple screening questionnaire and a bedside portable sleep study. Cardiac patients diagnosed with OSA can be pre-emptively given extra attention in managing their postoperative care.

Mediastinal liposarcoma: a rare visceral mediastinal tumour

Liposarcoma is the second most common type of soft tissue malignancy in adults. They are malignant tumours with a mesenchymal origin. Mediastinal liposarcoma accounts for <1% of mediastinal tumours and 2% of liposarcoma. We report a patient with mediastinal liposarcoma who presented with cardiac tamponade, 25 years after the initial liposarcoma in the popliteal fossa.

Quantitative and qualitative comparison of low- and high-cost 3D-printed heart models

Current visualization techniques of complex congenital heart disease (CHD) are unable to provide comprehensive visualization of the anomalous cardiac anatomy as the medical datasets can essentially only be viewed from a flat, two-dimensional (2D) screen. Three-dimensional (3D) printing has therefore been used to replicate patient-specific hearts in 3D views based on medical imaging datasets. This technique has been shown to have a positive impact on the preoperative planning of corrective surgery, patient-doctor communication, and the learning experience of medical students. However, 3D printing is often costly, and this impedes the routine application of this technology in clinical practice. This technical note aims to investigate whether reducing 3D printing costs can have any impact on the clinical value of the 3D-printed heart models. Low-cost and a high-cost 3D-printed models based on a selected case of CHD were generated with materials of differing cost. Quantitative assessment of dimensional accuracy of the cardiac anatomy and pathology was compared between the 3D-printed models and the original cardiac computed tomography (CT) images with excellent correlation (r=0.99). Qualitative evaluation of model usefulness showed no difference between the two models in medical applications.

Flow pattern analysis in type B aortic dissection patients after stent-grafting repair: Comparison between complete and incomplete false lumen thrombosis

Endovascular stent graft repair has become a common treatment for complicated Stanford type B aortic dissection to restore true lumen flow and induce false lumen thrombosis. Using computational fluid dynamics, this study reports the differences in flow patterns and wall shear stress distribution in complicated Stanford type B aortic dissection patients after endovascular stent graft repair. Five patients were included in this study: 2 have more than 80% false lumen thrombosis (group 1), while 3 others had less than 80% false lumen thrombosis (group 2) within 1 year following endovascular repair. Group 1 patients had concentrated re-entry tears around the abdominal branches only, while group 2 patients had re-entry tears that spread along the dissection line. Blood flow inside the false lumen which affected thrombus formation increased with the number of re-entry tears and when only small amounts of blood that entered the false lumen exited through the branches. In those cases where dissection extended below the abdominal branches (group 2), patients with fewer re-entry tears and longer distance between the tears had low wall shear stress contributing to thrombosis. This work provides an insight into predicting the development of complete or incomplete false lumen thrombosis and has implications for patient selection for treatment.

Metastatic Adenocarcinoma Presenting as Extensive Cavoatrial Tumor Thrombus

The presence of tumor thrombus in the right atrium is frequently the result of direct intraluminal extension of infra-diaphragmatic malignancy into the inferior vena cava (IVC) or supradiaphragmatic carcinoma into the superior vena cava (SVC). Right atrial tumor thrombus with extension into both SVC and IVC has not been reported in the literature. We present a patient who presented with symptoms of right atrial and SVC obstruction. Imaging revealed presence of a thrombus in the right atrium, extending to the SVC and IVC, with the additional findings of a left adrenal mass and multiple liver lesions. The histopathological examination of the right atrial mass revealed metastatic adenocarcinoma cells. The patient was given a presumptive diagnosis of metastatic adenocarcinoma, most likely adrenal in origin, with multiple hepatic lesions suspicious for metastasis. The clinical outcome of the patient was not favorable; the patient succumbed before the adrenal mass could be confirmed to be the primary tumor. This case highlights that in patients manifesting with extensive cavoatrial thrombus as, the existence of primary carcinoma should be considered especially in the adrenal cortex or in the lung.

A perspective review on numerical simulations of hemodynamics in aortic dissection

Aortic dissection, characterized by separation of the layers of the aortic wall, poses a significant challenge for clinicians. While type A aortic dissection patients are normally managed using surgical treatment, optimal treatment strategy for type B aortic dissection remains controversial and requires further evaluation. Although aortic diameter measured by CT angiography has been clinically used as a guideline to predict dilation in aortic dissection, hemodynamic parameters (e.g., pressure and wall shear stress), geometrical factors, and composition of the aorta wall are known to substantially affect disease progression. Due to the limitations of cardiac imaging modalities, numerical simulations have been widely used for the prediction of disease progression and therapeutic outcomes, by providing detailed insights into the hemodynamics. This paper presents a comprehensive review of the existing numerical models developed to investigate reasons behind tear initiation and progression, as well as the effectiveness of various treatment strategies, particularly the stent graft treatment.

Electroretinographic detection of human brain dopamine response to oral food stimulation

OBJECTIVE

The activity of dopamine-dependent retinal signaling can be assessed using electroretinography. Response of this system to oral food stimulation might provide accessible insight into the brain dopamine response to oral stimuli as retinal dopamine concentration is dependent upon mid brain dopamine concentration was postulated.

DESIGN AND METHODS

Nine individuals had cone ERG (b wave) response to oral food stimulation and oral methylphenidate (MPH) administration measured on separate days, and completed self reported eating behavior questionnaires.

RESULTS

Significant and similar increases in b wave response to both stimuli (P = 0.012 and P = 0.042, MPH and food, respectively) and significant correlations of the food stimulated b wave amplitude with binge eating related behavior as measured by the Gormally Binge Eating Scale (r = 0.68, P = 0.044) and self-reported trait hunger as measured by the Stunkard and Messick Three Factor Eating Questionnaire (r = 0.67, P = 0.048) were found.

CONCLUSION

The significant increase in food stimulated dopamine dependent b wave amplitude and correlation with methylphenidate stimulated b wave amplitude suggest that ERG may offer a relatively inexpensive and accessible methodology for potentially assess dopaminergic responses to food and other externally applied stimuli that have been implicated in the pathogenesis of a number of human diseases.

The relationship between daytime and nighttime food intake in an obese night-eater

Some obese individuals consume food during awakenings from nighttime sleep. Three studies were conducted on a 28-year-old morbidly obese male with chronic sleeping complaints and insignificant weight loss, despite self-reported daily caloric restriction: I. For 3 mo, the subject recorded food intake for 24-h periods. Mean daytime intake was 1286 kcal +/- 386 (SD), and mean nighttime intake was 1036 kcal +/- 487 (SD). Caloric values of daytime and nighttime intake were negatively correlated, r = -0.22, df= 82, p < .05. II. Seven consecutive 24-h food intake recordings were obtained with an automated formula dispenser when the subject was an inpatient on a metabolic ward and received ad libitum formula as his sole food source. Mean daytime intake was 1245 +/- 662 (SD), and mean nighttime intake was 231 +/- 236 (SD). There was a non-significant negative correlation between daytime and nighttime intake, r = -0.32, df = 5, NS. III. The subject underwent polysomnographic studies on 2 non-consecutive nights, following the administration of either a low (600 kcal) or high (1800 kcal) daytime caloric condition. The subject, upon awakening from nighttime sleep, could eat from a platter of sandwich quarters placed at his bedside. The addition of 1200 kcal to daytime intake decreased nighttime intake by 654 kcal, or by 55% of the additional calories delivered during the day. The three studies (I, II, and III) show that daytime food intake can be negatively correlated with nighttime intake, and that daytime intake can influence nighttime intake in a documented obese night-eater.

Gastric capacity in normal, obese, and bulimic women

One function of the stomach is as a reservoir for food; hence, the stomach's capacity may limit the amount of food ingested. A stomach with a large capacity has been associated with bigger test meals. We compared the stomach capacity of three groups of women: normal (n=10), obese (n=11), and bulimic (n=10). Following an overnight fast, gastric capacity was estimated by filling a gastric balloon with water at 100 ml/min, with pauses for measuring intragastric pressure. One estimate was based on the maximum volume the subject could tolerate as indicated by a maximal rating of abdominal discomfort. Another estimate was based on the volume required to produce a given rise of intragastric pressure, 5 cm H(2)O. A third related measure was based on a maximal rating of fullness. Based on these estimates, the gastric capacity of the bulimics was the largest, with the obese subjects intermediate. We then separated the obese subjects according to whether they reported binge eating (n=6) or not (n=5). The gastric capacity of the binge-eating subset was similar to the bulimics, and the nonbinge-eating subset was similar to the normals. Thus, gastric capacity appears more related to binge eating behavior than to body weight.

Test meal intake in obese binge eaters in relation to mood and gender

OBJECTIVE

We assessed test meal intake in men and women with and without binge eating disorder (BED) in relation to mood score (Zung scale).

METHODS

Eighty-five overweight subjects (24 males and 61 females) participated; 30 subjects with BED and 55 without BED. Following an 8-hr fast, subjects consumed a liquid test meal until extremely full.

RESULTS

BED subjects consumed significantly more (p =.009) of the test meal (1,032 g +/- 429) than the non-binge eaters (737 g +/- 399). The men ingested more than the women (p =.002). BED subjects also had higher depression scores (p =.01), without differing by gender. However, depression scores were unrelated to test meal intakes (r = -.01).

DISCUSSION

The larger meal intakes of the BED group may be due to the larger stomach capacity previously found in both bulimics and obese subjects. The findings also support the premise that BED, listed in the DSM-IV appendix for further study, is found in a distinct subgroup of overweight individuals.

High-fat diet feeding elevates skeletal muscle uncoupling protein 3 levels but not its activity in rats

OBJECTIVE

The objective of this study is to test the impact of high-fat diet (HFD) feeding on skeletal muscle (SM) uncoupling protein 3 (UCP3) expression and its association with mitochondrial ion permeability and whole-body energy homeostasis.

RESEARCH METHODS AND PROCEDURES

Sprague-Dawley rats were fed ad libitum either a HFD (60% of energy from fat, n = 6) or a low-fat diet (12% of energy from fat, n = 6) for 4 weeks. Twenty-four-hour energy expenditure was measured by indirect calorimetry in the last week of the dietary treatment. Blood samples were collected for plasma leptin and free fatty acid assays, and mitochondria were isolated from hindlimb SM for subsequent determinations of UCP3 levels and mitochondrial ion permeability.

RESULTS

Plasma leptin levels were higher in rats fed the HFD despite the same body weight in two groups. The same dietary treatment also rendered a 2-fold increase in plasma free fatty acid and SM UCP3 protein levels (Western blot) compared with the group fed the low-fat diet. However, the elevated UCP3 protein levels did not correlate with mitochondrial swelling rates, a measure of mitochondrial chloride, and proton permeability, or with 24-hour energy expenditure.

DISCUSSION

The high correlation between the levels of plasma free fatty acid levels and SM UCP3 suggests that circulating free fatty acid may play an important role in UCP3 expression during the HFD feeding. However, the dissociation between the UCP3 protein levels and 24-hour energy expenditure as well as mitochondrial ion permeability suggests that mitochondrial proton leak mediated by muscle UCP3 may not be a major contributor in energy balance in HFD feeding, and other regulatory mechanisms independent of gene regulation may be responsible for the control of UCP3-mediated uncoupling activity.

High protein vs high carbohydrate hypoenergetic diet for the treatment of obese hyperinsulinemic subjects

OBJECTIVE

To test the hypothesis that hyperinsulinemic obese subjects would respond differently to changes in the composition of hypoenergetic diets.

DESIGN

A 4-week randomized dietary intervention trial.

SUBJECTS

Thirteen male obese hyperinsulinemic normoglycemic subjects were divided into two groups and fed hypoenergetic diets providing 80% of their resting energy expenditure (REE). One group received a high-protein diet (HP; 45% protein, 25% carbohydrates, and 30% fat as percent of dietary energy) and the other a high-carbohydrate diet (HC; 12% protein, 58% carbohydrates and 30% fat).

MEASUREMENTS

Anthropometry, body composition, fasting serum insulin and lipids, and REE were performed before and after the feeding period.

RESULTS

Weight loss was higher in the HP than HC group (8.3+/-0.7 vs 6.0+/-0.6 kg, P<0. 05). There was a decrease in body fat in both groups, whereas body water decreased significantly more in the HP group. REE decreased more in the HC than the HP group (-384.3+/-84.6 vs -132.3+/-51.0 kcal, P<0.05). Serum total cholesterol, triglycerides and LDL cholesterol decreased significantly to a similar extent in both diet groups, while HDL cholesterol was decreased significantly only in the HP group. Mean fasting insulin decreased significantly in both diet groups and reached the normal range only in the HP group.

CONCLUSION

A low-carbohydrate (LC), HP hypoenergetic diet could be the diet composition of choice for a weight-reducing regimen in obese hyperinsulinemic subjects.

Effects of strength or aerobic training on body composition, resting metabolic rate, and peak oxygen consumption in obese dieting subjects

Given that resting metabolic rate (RMR) is related largely to the amount of fat-free mass (FFM), the hypothesis was that strength training, which stimulates muscle hypertrophy, would help preserve both FFM and RMR during dieting. In a randomized controlled intervention trial, moderately obese subjects (aged 19-48 y) were assigned to one of three groups: diet plus strength training, diet plus aerobic training, or diet only. Sixty-five subjects (25 men and 40 women) completed the study. They received a formula diet with an energy content of 70% of RMR or 5150 +/- 1070 kJ/d (x +/- SD) during the 8-wk intervention. They were seen weekly for individual nutritional counseling. Subjects in the two exercise groups, designed to be isoenergetic, trained three times per week under supervision. Those in the strength-training group performed progressive weight-resistance exercises for the upper and lower body. Those in the aerobic group performed alternate leg and arm cycling. After 8 wk, the mean amount of weight lost, 9.0 kg, did not differ significantly among groups. The strength-training group, however, lost significantly less FFM (P < 0.05) than the aerobic and diet-only groups. The strength-training group also showed significant increases (P < 0.05) in anthropometrically measured flexed arm muscle mass and grip strength. Mean RMR declined significantly, without differing among groups. Peak oxygen consumption increased the most for the aerobic group (P = 0.03). In conclusion, strength training significantly reduced the loss of FFM during dieting but did not prevent the decline in RMR.

Reduced stomach capacity in obese subjects after dieting

The objective of the study was to assess the change in gastric capacity of obese subjects consuming a hypoenergetic diet. Otherwise healthy, obese subjects participated in a prospective controlled study as hospital outpatients. Fourteen (11 females, 3 males) subjects were assigned to the diet group and 9 (7 females, 2 males) were assigned to the control group. Subjects in the diet group were provided a 2508-kJ/d(600 kcal/d) formula diet for 4 wk. Subjects in the control group ate ad libitum for 4 wk. Gastric capacity was determined before the study and 4 wk later by oral insertion of a latex gastric balloon after an overnight fast. The balloon was infused with water at a rate of 100 mL/min, with pauses for measuring intragastric pressure, until no further distension was tolerated. Two indexes for estimating gastric capacity were used based on subjective and objective criteria: 1) the maximal volume that could be tolerated, and 2) the volume required to produce a rise in water pressure of 5 cm. Subjects in the diet group, who lost a mean of 9.1 kg, showed a 27% reduction in gastric capacity based on the first index (P = 0.004) and a 36% reduction based on the second index (P = 0.006). For the control subjects, gastric capacity did not change significantly with use of either index. The results demonstrate a reduction in gastric capacity in obese subjects after a restricted diet.

Improvement of plasma lipoprotein profiles during high-flux dialysis

Patients undergoing maintenance hemodialysis therapy have increased mortality due to cardiovascular disease. One possible etiologic factor for this increased mortality is the lipid abnormalities associated with chronic renal failure. These include elevated triglyceride (TG) and decreased high-density lipoprotein (HDL) concentrations. Lipoprotein profiles of patients undergoing chronic hemodialysis with either saponified cellulose ester (CE) (N = 9) or polysulfone (PS) high-flux dialysis membranes (N = 10) were compared. Patients in each group received similar amounts of heparin during the dialysis. CE-dialyzed patients showed no alteration in serum TG, HDL, low-density lipoprotein, or total cholesterol when predialysis and postdialysis values were compared. PS patients, on the other hand, had a significant decrease in TG concentrations (P < 0.01) as well as a significant rise in HDL (P < 0.01). These changes might signify activation of lipoprotein lipase (LPL) during dialysis. LPL activity in PS sera was significantly greater than LPL in CE sera. Moreover, sera from PS patients inhibited LPL much less than did sera from CE patients. These findings suggest that a circulating substance not dialyzable with cellulosic membranes inhibits LPL in uremic subjects and is removed during dialysis with a PS membrane. Alternatively, the greater biocompatibility of PS may produce less LPL inhibitory cytokines during dialysis. The improvement of lipoprotein profiles in patients receiving dialysis with PS membranes may, in the long term, lead to less morbidity and mortality from atherosclerotic disease.

Gastric capacity, gastric emptying, and test-meal intake in normal and bulimic women

The role of the stomach in regulating appetite in bulimia nervosa was examined. Subjects were nine normal and nine bulimic women of similar age, height, and weight. Gastric capacity was estimated by filling a balloon in the stomach. The mean stomach capacity of bulimic subjects was significantly larger than that of normal subjects, as revealed by the larger balloon volume tolerated (P less than 0.01) and by the larger volume needed to produce a 5 cm H2O increase in intragastric pressure (P = 0.07). The intake of a liquid meal was also significantly larger for the bulimic subjects. Gastric-emptying rate of a liquid meal was significantly delayed in the bulimic subjects during the initial 5-15 min. In all subjects, test-meal intake correlated significantly with gastric capacity (r = 0.53). In the bulimic subjects, self-reported binge intake (J) also correlated significantly with gastric capacity (r = 0.75). Binge eating in bulimic subjects may enlarge gastric capacity, which could then promote even larger binges through positive feedback.

Clinical trial of silicone-rubber gastric balloon to treat obesity

A study was conducted to test the efficacy and safety of a 300 ml silicone-rubber gastric balloon for weight reduction. Eighty-six obese subjects were distributed into four groups: (1) gastric balloon only, (2) gastric balloon and prescribed 1000 kcal/day (239 kJ) diet, (3) 1000 kcal/day diet only, and (4) no treatment. The intervention period was 3 months. The balloon only group lost 3.2 kg +/- 0.9 (s.e.), the balloon and diet group lost 5.1 +/- 1.0 kg, the diet group lost 6.9 +/- 1.4 kg and the control group gained 0.6 +/- 0.5 kg. The three intervention groups each lost significantly more weight than the control group. The diet only group lost significantly more weight than the balloon only group. Body densitometry showed that the treatment groups lost a significant amount of body fat. Gastroscopy revealed three ulcers and two superficial erosions at balloon removal. The gastric balloons were well tolerated despite gastric spasms and nausea which abated after the initial 24-48 hours. Gastric capacity was determined in a subset of 19 subjects from the two balloon groups before the intervention by distending the stomach with a balloon and calculating the volume required to produce an increase in intragastric pressure of 5 cm H2O. Subjects with a smaller gastric capacity lost more weight with the balloon than subjects with a large capacity (r = 0.45, P less than 0.05). These results suggest that for improved efficacy, balloon volume may need to be larger than 300 ml or adjusted to the individual's gastric capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric balloon to treat obesity: a double-blind study in nondieting subjects

To determine its efficacy and safety in treating obesity, a silicone-rubber balloon was passed into the stomach of 10 nondieting, obese subjects. In a counterbalanced sequence, the balloon was inflated with 400 mL for 1 mo and deflated for 1 mo. Lower intakes of solid and liquid test meals (NS), significantly slower gastric emptying, and concomitant changes in glucose, insulin, glucagon, and cholecystokinin concentrations consistent with slower emptying resulted during balloon inflation. After balloon inflation, one small gastric ulcer developed, which subsequently healed. Significant weight loss occurred during the second and third week of the inflation period (F[1,9] = 5.0, p less than 0.05). However, the weight loss was small and the significant effect did not continue through the fourth week.

Polysiloxane: potential noncaloric fat substitute; effects on body composition of obese Zucker rats

Phenylmethylpolysiloxane (PS), a noncaloric, nonabsorbable liquid oil, was studied for effects on body comparison as fat substitute in the diet. Two groups of female obese Zucker rats were fed either a control low-fat (LF) or an experimental diet containing PS (22% wt/wt) incorporated into LF. Two additional groups were fed either PS or cellulose (CE) in diet providing equivalent caloric dilution. Rats on PS lost weight whereas LF control rats gained. Dissectible fat and adipocyte size of PS were smaller than those of LF. Food intake, body water, and adipocyte number did not differ between PS and LF. Body protein on PS increased only in proportion to weight. When both diets were diluted, PS animals lost more weight than CE controls despite similar food intakes, suggesting absorption of calorigenic substances derived from partial digestion of CE but not PS by intestinal microflora. Obese rats did not compensate for caloric dilution with PS.

Role of brown adipose tissue in thermogenesis induced by overfeeding a diet containing medium chain triglyceride

The role of brown adipose tissue in the mechanism of medium chain triglyceride (MCT)-induced thermogenesis was investigated. Under anesthesia, the interscapular brown adipose tissue (IBAT) was excised in male Sprague-Dawley rats, and the animals were fitted with gastrostomy tubes. After a 10-day recovery period, the animals were divided into two groups: one group received a diet containing MCT as 50% of calories, and the other group received an isocaloric diet containing long chain triglyceride (LCT). The diets were fed for 6 wk at a level of calorie intake that was 150% of the ad libitum intake of a parallel control group. During the last week of the study, resting and norepinephrine (NE)-stimulated O2 consumption and CO2 production were measured in a Noyons diaferometer. At the end of 6 wk, the animals were weighed and killed. The individual fat pads were dissected and weighed, and an aliquot of the right retroperitoneal fat pad was used to measure adipocyte size and number. The results showed that body weight and adipocyte size (but not adipocyte number) were significantly smaller in the MCT-fed compared to the LCT-fed animals. Resting as well as maximal NE-stimulated oxygen consumption values were significantly higher in the MCT-fed than the LCT-fed rats. It is concluded that the enhanced thermogenesis induced by MCT persists despite the absence of IBAT and that the phenomenon is likely related to more extensive oxidation of MCT- in contrast to LCT-derived fatty acids, thus leading to increased oxygen consumption, enhanced dissipation of energy as heat and diminished efficiency of weight gain and deposition of body fat.

Medium chain triglyceride in early life: effects on growth of adipose tissue

Effects of feeding early in life a diet high in either long chain (LCT) or medium chain triglyceride (MCT) were studied on the development of adipose tissue in post-weanling rats. The diets were similar in calorie distribution and identical in nutrients except for type of fat. The caloric distribution of the two diets by percent was LCT (corn oil)/protein/carbohydrate, 70/18/12 and MCT/corn oil/protein/carbohydrate, 66/4/18/12. Male littermates with less than 5% weight difference were pair-fed the two diets randomly at age 18-20 days. One-fourth of the rats were killed at 10, 16, 22 and 28 weeks of age and analyzed for adipose depots and adipose tissue cellularity. Results showed that the LCT-fed rats were significantly heavier, with larger epididymal, retroperitoneal, omental and subcutaneous fat pads than the respective pair-fed MCT rats. Also, LCT-fed rats had larger size and number of adipocytes than MCT-fed littermates. It is concluded that the type of fat in the diet, namely LCT or MCT, when fed early in life can influence the development of adipose tissue. MCT appears less lipogenic than LCT. The mechanism for the diminished adiposity of MCT-fed rats is related to extensive oxidation of MCT and its enhancement of thermogenesis leading to lessened energy efficiency.

Gastric balloon reduces food intake and body weight in obese rats

A less invasive method than gastric reduction surgery for treating obesity was tested by inserting balloons into the stomachs of obese rats. Male Sprague-Dawley rats were placed on a high fat diet. After 4 months, the rats weighed an average of 750 g or 23% more than rats on a chow diet. Balloons were then passed orally into the stomach, inflated with 10 ml of water, and detached from the inflating tube. Eight rats had inflated balloons; six rats had no balloons. The balloons, which could be palpated, remained inflated for 12 to 49 days with a mean of 25 days. During the period of inflation, rats with balloons consumed significantly less food (p less than 0.001) relative to rats without balloons. Gastric emptying rate was significantly slowed (p less than 0.0025) in rats with inflated balloons compared to rats with balloons that had deflated and rats with no balloons. Histology of the stomachs that held inflated balloons did not reveal pathology.

Intragastric balloon reduces food intake and body weight in rats

To test a less invasive method than gastric surgery for treating obesity, balloons were nonsurgically inserted in the stomachs of adult rats (mean wt = 537 g) for 8 wk. One group received balloons that were inflated with 7 ml of water, a second group had balloons inserted that were deflated, and a third group had no balloons inserted. Rats with inflated balloons ingested 27% less food (P less than 0.0005) during the 8 wk and weighted 16% less (P less than 0.05) at the end of this period than rats with deflated balloons or no balloons. Their food intake was significantly depressed through the 7th wk. The stomachs of the rats with inflated balloons were significantly heavier than the others with a thicker muscularis externa. Body composition was not significantly different among groups. A chronic intragastric balloon significantly reduced food intake and body weight.

Naltrexone and human eating behavior: a dose-ranging inpatient trial in moderately obese men

To investigate the effects of the long-acting opiate antagonist naltrexone on spontaneous human eating behavior, eight moderately obese male paid volunteers were housed in a hospital metabolic unit for 28 days and offered palatable foods ad lib by a platter service method. Under double-blind conditions, equally divided doses of 100, 200 and 300 mg naltrexone, or an acetaminophen placebo, were administered twice daily in tablet form for 3-day periods each, according to a Latin Square design. The doses of naltrexone resulted in decreases of daily caloric intake from placebo level, but these reductions were neither statistically significant nor dose-related. When the averaged effects of the doses were compared to placebo, five subjects showed intake reductions but the overall intake reduction of 301.5 +/- 198.1 kcal/day (mean +/- SEM) was not statistically significant. Naltrexone administration failed to selectively alter intakes of individual meals and snacks or macronutrient consumption patterns. During active drug periods, subjects lost 0.62 +/- 0.22 lb over 3 days, while during the placebo period, subjects gained 0.46 +/- 0.68 lb. However, there was no reliable change of basal metabolic rate as a function of naltrexone administration. The present results, which indicate that naltrexone administration is relatively ineffective in reducing food intake and inducing body weight loss in obese humans, are thus in contrast with reports that administration of opiate antagonist agents promote significant reductions of food intake and attenuations of body weight gain in experimental animals.

Insulin increases body fat despite control of food intake and physical activity

The effect of experimentally induced hyperinsulinemia on body composition was studied in rats with food intakes precisely controlled by intragastric feeding and physical activity manipulated by sedation with chlordiazepoxide (CDP). Male Sprague-Dawley rats (n = 38) were fitted surgically with gastrostomy tubes. After 8 days the animals were divided into four groups. Group 1 received daily injections of protamine-zinc insulin; group 2 received daily injections of saline; group 3 received the same insulin doses as group 1 plus daily administration of CDP mixed with the diet; group 4 received daily injections of saline plus CDP in the diet. All groups were tubefed identical amounts of semiliquid diet via gastrostomy. Physical activity was measured by electronic monitor. After 4 wk the rats were killed. The insulin-treated groups (1 and 3) had significantly larger fat depots and larger mean fat cell size than the noninsulin-treated groups (2 and 4). This increase in fat occurred concurrently with a decrease in carcass protein and water. Physical activity, as measured, was unaltered by insulin but was significantly reduced by CDP. Treatment with CDP only increased the dorsal fat depot and liver weight but had no significant effect on total dissected fat depots and had a reductive effect on carcass protein. In conclusion insulin treatment enhanced the efficiency of conversion of energy intake into fat energy stores.

A new method for estimation of body composition in the live rat

Measurement of total body electrical conductivity (TOBEC) has been used to estimate lean and fat content of meat based on the principle that electrical conductivity of lean tissue is far greater than that of fat. This approach was used to estimate body composition of live rats. An instrument designed for commercial analysis of ground meat (DjMe 100) was used to measure TOBEC in 30 male Sprague-Dawley rats (197-433 g). Individual TOBEC values were obtained in 20 seconds and repeated twice for each rat. The animals were then killed with ether, hair was shaved, lungs collapsed and body density measured hydrostatically. Carcasses were homogenized and analyzed for fat, nitrogen, and water. A high correlation was found between TOBEC and lean body mass by densitometry (r = .97) and between TOBEC and fat-free mass derived from direct carcass analysis (r = .97). Rats weighing up to 450 g could be accommodated in this particular instrument. Measurement of TOBEC should prove useful in estimating body composition and monitoring its changes in live rats and other small laboratory animals.

Overfeeding with medium-chain triglyceride diet results in diminished deposition of fat

The study was designed to determine whether overfeeding rats with a diet containing medium-chain triglyceride (MCT) as the major fat source (45% of calories) would impede the expected gain in weight and body fat as compared to rats overfed with isocaloric amounts of diet containing long-chain triglyceride (LCT). For 6 wk rats were fed either MCT diet or LCT diet twice daily via a gastrostomy tube. MCT-fed rats gained 20% less weight (P less than 0.001) and possessed fat depots weighing 23% less (p less than 0.001) than LCT)-fed rats. Mean adipocyte size was smaller (p less than 0.005) in MCT- than in LCT-fed rats. Weights of carcass protein and water were similar for both groups as were concentrations of serum insulin and levels of physical activity. The decreased deposition of fat in the MCT-fed rats may have resulted from obligatory oxidation of MCT-derived fatty acids in the liver after being transported there via the portal vein, leaving almost no MCT derivatives for incorporation into body fat. MCT may have potential for dietary prevention of human obesity.

Enhanced thermogenesis and diminished deposition of fat in response to overfeeding with diet containing medium chain triglyceride

The mechanism whereby overfeeding with diet containing medium chain triglyceride (MCT) results in diminished body weight and fat was studied. Fifteen male Sprague-Dawley rats were fitted under anesthesia with gastrostomy tubes and divided into two groups. One group was fed MCT diet, the other an isocaloric diet containing long chain triglyceride (LCT) in excess (150%) of spontaneous calorie intake. Both diets, fed for 6 wk, derived 50% of calories from fat. Basal and norepinephrine (25 micrograms/100 g) stimulated 02 consumption and CO2 production, as well as metabolic rate were measured. After the rats were killed, total dissectible fat and fat cell size and number were determined. MCT rats gained 15% less weight than LCT controls (p less than 0.001). Total dissectible fat was significantly lower (p less than 0.001) in MCT group, as was mean adipocyte size (p less than 0.001). Resting and maximal norepinephrine-stimulated 02 consumptions were 39.7 and 22.1% higher in MCT than in LCT group, respectively. Resting and norepinephrine-stimulated metabolic rates were 38.8 and 22.2% higher in MCT than LCT fed rats, respectively. Overfeeding MCT diet results in decreased body fat related to increased metabolic rate and thermogenesis.

Lysolecithin acyltransferase and alveolar phosphatidylcholine palmitate in experimental acute alveolar injury in the dog lung

Lysolecithin acyltransferase (EC 2.3.1.23) activities in lung homogenates and in subcellular fractions, and fatty acid composition of phosphatidylcholine (PC) in lung lavage were studied in dogs with acute alveolar injury induced by N-nitroso-N-methylurethane. The specific activity in the microsomal fraction was 10 and 3 times higher than those of homogenate and mitochondrial fractions, respectively. Both the lysolecithin acyltransferase activities and the proportions of palmitate in alveolar lavage PC increased during the early phase of injury (days 2-4), and decreased during peak injury (days 6-8). Such correlation was not found during the recovery period (day 15). During recovery, specific and total activities of the enzyme were nearly 2- and 3-fold, respectively, those of controls. Nevertheless, the palmitate proportions in PC were normal, indicating that the increased enzyme activity in vitro was not reflected in increased PC palmitate during recovery. This finding indicates that the enzyme activity per cell was normal during recovery and suggests that the increase in specific and total activities is due to massive regeneration of type II cells and that the enzyme is localized mainly in these cells. The decrease in the proportion of palmitate in lavage PC during peak injury may lead to abnormality of surfactant function.

Alcohol-induced lipid change in th lung

Quantities and qualities of lipids in lung lavage and lavaged lung tissue were studied in ethanol-fed male Sprague-Dawley rats. Experimental rats received 36% of daily energy as ethanol for 7 weeks and each control rat, receiving an isocaloric amount of sucrose, was pair-fed with an experimental rat. Body weight gain and lung protein content in these two groups were similar. The mean lung dry weight of ethanol-fed rats as compared to controls was significantly elevated. The quantity of phosphatidylcholine (PC), a key surfactant lipid, recovered from lung lavage of ethanol-fed rats was double that of controls, but the proportion of palmitate in its fatty acids was reduced. The content of cholesterol and cholesteryl ester in lung lavage of ethanol-fed rats was nearly twice that of controls but the content of triglyceride was not different. The quantity and quality of PC in lung tissue were not significantly different between these two groups. Triglyceride content of lung tissue in ethanol-fed rats was nearly three times that of controls. Ethanol increased the proportion of oleic and decreased the relative amount of palmitic, palmitoleic, and linoleic acids in triglycerides of lung tissue.

Correlation of lung compliance and quantities of surfactant phospholipids after acute alveolar injury from N-nitroso-N-methylurethane in the dog

Acute alveolar injury was induced in dogs by subcutaneous injection of 8 mg of N-nitroso-N-methylurethane per kg of body weight. Two to seven days after the injections, the change in respiratory compliance was measured, alveolar and lung tissue disaturated phosphatidyl choline (DSPC) were quantified, and fatty acid patterns of alveolar phosphatidyl choline were determined. Progressive decreases occurred in respiratory compliance and in alveolar and tissue DSPC. Mean alveolar DSPC decreases occurred in respiratory compliance and in alveolar and tissue DSPC. Mean alveolar DSPC decreased to 22% (p less than 0.001) of that of the control study and significant linear correlation (p = 0.02) between respiratory compliance and alveolar DSPC quantity was found. Mean tissue DSPC decreased to 60% of that of the control study (p less than 0.001) and reductions in alveolar and in type II cell DSPC were estimated to be nearly equivalent. The proportion of palmitate in lavage phosphatidyl choline was increased by a mean of 9%. These studies demonstrated a decrease in surfactant lipids correlated with decreased compliances in acute alveolar injury and suggested that qualitative and quantitative changes in surfactant result from injury to alveolar type II cells.

Quantification of surfactant phospholipids in the dog lung

We quantified total phospholipid (PL), total and disaturated phosphatidylcholine (PC and DSPC), phosphatidylglycerol (PG), and total protein in alveolar washings and lung tissue in 22 dog lungs. Quantitative recovery of alveolar material and assessment of its possible contamination by blood lipids were important determinants of methodology. To remove blood, the vessels of half the lungs were perfused with a fluorocarbon emulsion before lavage. The volume of blood removed by perfusion and the quantity and fatty acid patterns of its whole blood and plasma PL and PC were determined. Washings of unperfused lungs contained means of 21% more PL and 24% more PC than those of perfused lungs. Although this excess could be accounted for by the PL and PC in pulmonary blood, the hemoglobin and total protein content of washings and their PC fatty acid patterns indicated that blood lipids were not a major source of the excess lipid in washings of unperfused lungs. Using more recent morphometric estimates rather than the indirect ones previously used by others, the quantity of alveolar DSPC (1 mg/g lung) is calculated to be 1.8 times the amount necessary to form a packed monolayer on the internal surface of the lung at functional residual capacity.

Estimation of phosphatidylglycerol in fluids containing pulmonary surfactant

A simple, direct and non-destructive method for quantitative separation of phosphatidylglycerol from other phospholipids in pulmonary washings is described. Total lipid extracts from dog lung washings and phosphatidylglycerol standard were spotted quantitatively on chromatoplates and separated by one-dimensional thin-layer chromatography in chloroform-methanol-water 65:25:4 (v/v/v). Quantification was performed with Rhodamine 6G and fluorometry. Washings from eleven dogs contained (mean +/- S.E.) 236 +/- 25 microgram phosphatidylglycerol per g of parenchymal wet lung tissue which accounted for 8.7% +/- 2.3 of the total phospholipids. The procedure is especially useful for quantification of phosphatidylglycerol in microgram amounts.

Ingestive behavior and composition of weight change during cyproheptadine administration

The effect of cyproheptadine on spontaneous energy intake was studied by means of an automated (liquid diet) food-dispensing apparatus in two nonobese adults confined to a metabolic ward. The experimental design included both single and double-blind periods. Throughout, the composition of daily weight change was determined by the energy-nitrogen balance method. While on cyproheptadine, both subjects exhibited increases in energy intake with the following average composition of weight gain: protein 16%, fat 14% and water 70% (first subject), and protein 5%, fat 49% and water 46% (second subject). The cyproheptadine-induced increase in energy intake was statistically significant in one of the subjects, who was at his desirable weight level at the outset. The other subject was underweight initially and tended to gain throughout the experiment, although rate of weight gain appeared to be more rapid during the periods of cyproheptadine administration. Energy output in both subjects remained fairly constant throughout. We conclude that cyproheptadine induces weight gain of 'normal' composition by stimulating increased energy intake.

Studies in man of partially absorbed dietary fats

A saturated long-chain triglyceride (SLCT) has been prepared by esterification with glycerol of the saturated long-chain fatty acid fraction of coconut oil, isolated by molecular distillation of the hydrolyzed oil. The resultant SLCT is comprised principally of stearate (89%) and palmitate (11%). The intestinal absorption of SLCT in man was compared with that of corn oil or a 1:1 mixture of SLCT and corn oil. Each fat or the mixture was incorporated in isocaloric amounts into a complete formula diet deriving 30% of its caloric content from fat, 55% from carbohydrate (dextrose), and 15% from protein (casein). The formula diets were administered in sequential feeding periods as the sole source of food. The results indicate that SLCT was poorly absorbed (31 to 39%) compared with virtually complete absorption of corn oil (98%). Fat absorption was improved when the dietary fat was an equal mixture of SLCT and corn oil. The poor absorption of SLCT was ascribed to its high melting point and related to impaired emulsification and micellar solubilization in the small intestine.

Medium-chain triglyceride feeding in premature infants: effects on calcium and magnesium absorption

The effect of medium-chain triglycerides (MCT) on the absorption of calcium and magnesium in premature infants was studied in 34 infants with birth weights lower than 2,000 gm. The infants were divided into three groups and fed three formulas similar in nutrient content except for the type of fat, as follows: group 1 (control): corn oil, oleo, and coconut oil (39:41:20); group 2: MCT, corn oil, and coconut oil (40:40:20); group 3: MCT and corn oil (80:20). The infants fed MCT-containing formulas absorbed significantly more calcium than the control group. Magnesium absorption was significantly increased in the 80% MCT group.