Comparative evaluation of HD 2D/3D laparoscopic monitors and benchmarking to a theoretically ideal 3D pseudodisplay: even well-experienced laparoscopists perform better with 3D.

BACKGROUND: Though theoretically superior to standard 2D visualization, 3D video systems have not yet achieved a breakthrough in laparoscopy. The latest 3D monitors, including autostereoscopic displays and high-definition (HD) resolution, are designed to overcome the existing limitations. METHODS: We performed a randomized study on 48 individuals with different experience levels in laparoscopy. Three different 3D displays (glasses-based 3D monitor, autostereoscopic display, and a mirror-based theoretically ideal 3D display) were compared to a 2D HD display by assessing multiple performance and mental workload parameters and rating the subjects during a laparoscopic suturing task. Electromagnetic tracking provided information on the instruments' pathlength, movement velocity, and economy. The usability, the perception of visual discomfort, and the quality of image transmission of each monitor were subjectively rated. RESULTS: Almost all performance parameters were superior with the conventional glasses-based 3D display compared to the 2D display and the autostereoscopic display, but were often significantly exceeded by the mirror-based 3D display. Subjects performed a task faster and with greater precision when visualization was achieved with the 3D and the mirror-based display. Instrument pathlength was shortened by improved depth perception. Workload parameters (NASA TLX) did not show significant differences. Test persons complained of impaired vision while using the autostereoscopic monitor. The 3D and 2D displays were rated user-friendly and applicable in daily work. Experienced and inexperienced laparoscopists profited equally from using a 3D display, with an improvement in task performance about 20%. CONCLUSION: Novel 3D displays improve laparoscopic interventions as a result of faster performance and higher precision without causing a higher mental workload. Therefore, they have the potential to significantly impact the further development of minimally invasive surgery. However, as shown by the custom-built 3D mirror display, this effect can be improved, thus stimulating further research.

Molecular dispersion energy parameters for alkali and halide ions in aqueous solution.

Thermodynamic properties of aqueous solutions containing alkali and halide ions are determined by molecular simulation. The following ions are studied: Li(+), Na(+), K(+), Rb(+), Cs(+), F(-), Cl(-), Br(-), and I(-). The employed ion force fields consist of one Lennard-Jones (LJ) site and one concentric point charge with a magnitude of ±1 e. The SPC/E model is used for water. The LJ size parameter of the ion models is taken from Deublein et al. [J. Chem. Phys. 136, 084501 (2012)], while the LJ energy parameter is determined in the present study based on experimental self-diffusion coefficient data of the alkali cations and the halide anions in aqueous solutions as well as the position of the first maximum of the radial distribution function of water around the ions. On the basis of these force field parameters, the electric conductivity, the hydration dynamics of water molecules around the ions, and the enthalpy of hydration is predicted. Considering a wide range of salinity, this study is conducted at temperatures of 293.15 and 298.15 K and a pressure of 1 bar.

Metabolic engineering of Arabidopsis and Brassica for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer production.

Poly(hydroxyalkanoates) are natural polymers with thermoplastic properties. One polymer of this class with commercial applicability, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) can be produced by bacterial fermentation, but the process is not economically competitive with polymer production from petrochemicals. Poly(hydroxyalkanoate) production in green plants promises much lower costs, but producing copolymer with the appropriate monomer composition is problematic. In this study, we have engineered Arabidopsis and Brassica to produce PHBV in leaves and seeds, respectively, by redirecting the metabolic flow of intermediates from fatty acid and amino acid biosynthesis. We present a pathway for the biosynthesis of PHBV in plant plastids, and also report copolymer production, metabolic intermediate analyses, and pathway dynamics.

Exercise adaptation responses for gastric inhibitory polypeptide (GIP) and insulin in obese children. Possible extra-pancreatic effects.

Thirteen obese children and matched controls were fed a mixed meal, and responses were evaluated at fixed intervals for glucose, insulin, and gastric inhibitory polypeptide (GIP). The obese children were evaluated before and within 48 h after completion of a 5-mo exercise training program (ETP). The ETP included three aerobic exercise sessions per week and modest diet restrictions. Caloric expenditure was increased by approximately 300 kcal/exercise session. Weight gain was minimal over the 5 mo. An unexpected increase in GIP response and improved insulin tolerance were recorded for the obese children post-ETP. GIP values were higher (P less than 0.05) at 30 and 60 min and led to a highly significant elevation (P less than 0.01) of the integrated GIP response for post-ETP obese versus both pre-ETP and normal-weight controls. Insulin values were lower (P less than 0.05) at 30 and 60 min and led to a lower integrated insulin response (P less than 0.0585) for post-ETP obese children. However, the obese children continued to secrete more insulin (P less than 0.05) than normal-weight controls. Glucose tolerance, similar for pre-ETP obese subjects and controls, did not change in post-ETP children. Exercise-induced improvement in glucose utilization in these obese children was associated with an increase in GIP secretion. This contrasts with reports that calorie restriction will improve glucose utilization with decreased insulin and GIP secretion. The study demonstrates a previously unreported uncoupling of GIP and insulin secretion and suggests shifts in peripheral tissue sensitivity to insulin-induced glucose uptake. These shifts may, in part, be influenced by GIP.

Refusing treatment for mental illness: historical and ethical dimensions.

The author summarizes the historical bases for overzealous intervention by physicians, noting the tensions among medical technology, nature as a healing force, and the physician's warrant to treat. He discusses John Mill's On Liberty and Gerald Dworkin's "Paternalism" and suggests that there are times when the intervention should be withheld, but never the care.

Dietary fructose or starch: effects on copper, zinc, iron, manganese, calcium, and magnesium balances in humans.

A balance study was conducted to assess the effects of consuming low-copper diets, high in fructose or cornstarch. The study involved 19 apparently healthy males, aged 21-57 y. The two experimental diets averaged 0.35 mg Cu/1000 kcal and provided 20% of the calories from fructose or cornstarch. Cu, zinc, calcium, magnesium, and iron balances were determined 1 wk before the study (pretest) when the subjects consumed self-selected diets and after consuming the experimental diets for 6 wk. No major differences in mineral balances were evident between the two groups during the pretest study when the subjects ate self-selected diets. In contrast, when fed the test diets, the group consuming the low-Cu fructose diet had significantly more positive balances for all minerals studied than the group fed the low-Cu cornstarch diet. The results indicate that dietary fructose enhances mineral balance.

Blood lipid distribution of hyperinsulinemic men consuming three levels of fructose.

Twelve carbohydrate-sensitive men selected due to their abnormally high insulin responses to a sucrose load and 12 men with normal insulin responses were fed diets containing 0, 7.5, and 15% fructose for 5 wk each in a cross-over design. The diets contained 43% total carbohydrate, 42% fat, and 15% protein. Initial fasting total cholesterol and low-density lipoprotein cholesterol were higher in the hyperinsulinemic men than in the controls. Diastolic blood pressure was not affected by diet, but systolic blood pressure was slightly higher after the men consumed the 0% fructose diet. Free fatty acids were not different. Total plasma cholesterol and low-density lipoprotein cholesterol were higher after the men consumed 7.5 and 15% fructose than when they consumed the 0% fructose diet. Plasma triglyceride increased significantly as fructose in the diets of the hyperinsulinemics increased, but was not affected in the controls. These changes in blood lipids are associated with heart disease.

Insulin and glucose responses in rats fed sucrose or starch.

Rats fed 54% sucrose for 11 to 13 weeks ad libitum or 5 weeks ad libitum followed by 6 to 8 weeks of meal feeding had significantly higher serum insulin, glucose, and triglyceride levels than rats fed comparable amounts of starch after 12 to 14 hr without food. The serum insulin response measured before, 1/2, and 4 hr after a meal showed insulin levels of sucrose-fed rats to be higher than comparable levels of rats fed starch at all three times. An intraperitoneal glucose tolerance test measuring serum glucose before, 1/2, 2, and 2 hr after a glucose injection revealed glucose levels of rats fed sucrose to be higher than levels of rats fed starch. When insulin was added to the injection medium, serum glucose of rats fed sucrose remained higher than comparable levels of rats fed starch indicating insulin insensitivity. Meal feeding generally resulted in higher insulin and triglyceride levels than in rats fed ad libitum but had little effect on glucose levels. These results are clear evidence that sucrose feeding has undesirable effects on glucose tolerance.

Effect of isocaloric exchange of dietary starch and sucrose in humans on the gastric inhibitory polypeptide response to a sucrose load.

Ten men and nine women aged 35 to 55 consumed two diets for 6 weeks each in a cross-over design. The diets were composed of identical natural foods and 30% of the calories as either sucrose or wheat starch. Carbohydrate, fat and protein supplied 43, 42, and 15% of the calories, respectively. The dietary pattern consisted of two meals divided so as to provide 10% of the calories at breakfast (7:00 to 8:30 AM) and 90% of the calories at dinner (4:30 to 6:30 PM). Initial body weights were essentially maintained. The gastric inhibitory polypeptide response after a sucrose load (2 g/kg body weight) was significantly greater (P < 0.01) after th subjects consumed the sucrose rather than the starch diet. The gastric inhibitory polypeptide response was significantly greater (P < 0.01) after 6 weeks on diet than during pretest. These results suggest that the increases in insulin levels observed after sucrose feeding may be mediated by an effect on the enteric hormone gastric inhibitory polypeptide.

Urinary chromium excretion and insulinogenic properties of carbohydrates.

Eleven male and nine female adult subjects were given one of the following five carbohydrate-drink combinations (per kg body wt) on five mornings separated by greater than or equal to 2 wk: 1) 1.0 g glucose, 2) 0.9 g uncooked cornstarch, 3) 1.0 g glucose followed 20 min later by 1.75 g fructose, 4) 0.9 g uncooked cornstarch followed 20 min later by 1.75 g fructose, and 5) water followed 20 min later by 1.75 g fructose. Glucose plus fructose was the most insulinogenic followed by glucose alone, starch plus fructose, starch alone, and water plus fructose. The urinary losses of chromium followed a similar pattern. Subjects with the highest concentrations of circulating insulin displayed decreased ability to mobilize chromium on the basis of urinary chromium excretion. Therefore, urinary chromium losses are related to the insulinogenic properties of carbohydrates.

An insulinogenic effect of oral fructose in humans during postprandial hyperglycemia.

This study proposed to determine whether the stimulation of insulin secretion observed in humans infused with fructose when glucose levels were elevated could be observed when fructose was consumed during postprandial hyperglycemia. At 2-wk intervals, healthy volunteers consumed drinks containing glucose, starch, glucose followed 20 min later by fructose, starch followed 20 min later by fructose, and water followed 20 min later by fructose. Fructose consumption following glucose or starch drinks produced significantly higher levels of plasma insulin, but not plasma glucose, as compared to corresponding drinks consumed without fructose. Ten subjects whose blood glucose response levels were above 155 mg% after a glucose-containing drink appeared to be particularly responsive to the effects of fructose with increases in insulin levels of 60-288%. Results indicate that oral fructose can be insulinogenic in humans when blood glucose levels are elevated.

Role of dietary fructose in the enhancement of mortality and biochemical changes associated with copper deficiency in rats.

Rats were fed copper deficient (0.9 microgram/g) or copper-supplemented diets in which the carbohydrate was either starch, sucrose, or fructose (62% by weight) for 7 wk. Regardless of the nature of the carbohydrate, copper deficiency decreased blood ceruloplasmin activity, hepatic copper and ATP levels, and increased plasma cholesterol and triglycerides. Copper deficiency in rats fed sucrose or fructose, but not those fed starch, significantly lowered blood hematocrit, Hb, and albumin and significantly increased heart and liver weight and the glucose response to a glycemic stress. Hepatic copper level was significantly lower in copper-deficient rats fed sucrose or fructose than in those fed starch. Fasting blood glucose, cholesterol, and triglyceride levels were significantly higher in copper deficient rats fed fructose than in those fed starch. During the study 14 copper-deficient rats died, one of 10 fed starch, six of 20 fed sucrose, and seven of 20 fed fructose. Death was apparently the result of rupture of the heart in the region of the apex. These results indicate that fructose-containing carbohydrates as compared to starch markedly increase the severity of copper deficiency in rats. Whether this effect is due to differences in the nature of the simple carbohydrate (fructose versus glucose) or to molecular size (simple versus complex carbohydrate) remains to be established.

The interaction of type of dietary carbohydrates with copper deficiency.

The present study was designed to determine if the more severe copper deficiency in rats fed sucrose and fructose, as compared to starch, is due to a specific effect of the fructose or to a nonspecific effect of any simple carbohydrate. Seventy weanling male rats were fed, for 9 wk, copper-deficient diets or copper-supplemented diets containing either 62% starch, fructose, or glucose. Decreased hematocrit, serum copper, and ceruloplasmin concentrations but increased heart and liver weights, total liver lipid, and hepatic iron concentrations were found in all copper-deficient rats regardless of the dietary carbohydrate. Feeding rats the high glucose diet decreased plasma albumin and liver glycogen but increased blood urea nitrogen when compared to rats fed starch. However, rats fed fructose generally exhibited a more severe copper deficiency as compared to rats fed either starch or glucose. The severity was characterized by lower (p less than 0.05) body weight, liver glycogen, hematocrit, serum copper, and albumin. Conversely, liver and heart weights, blood urea nitrogen, and plasma glutamic oxaloacetic transaminase were higher (p less than 0.05). Plasma cholesterol was increased by copper deficiency only in rats fed fructose or glucose. During the study, 17 of the 40 rats fed copper-deficient diets died; 66% of those fed fructose, 26% fed glucose, and 30% fed starch. These results suggest that the fructose moiety of sucrose is responsible for the increased severity of copper deficiency in rats fed sucrose as compared to starch.

Isocaloric exchange of dietary starch and sucrose in humans. I. Effects on levels of fasting blood lipids.

For 6 weeks, 10 men and nine women aged 35 to 55 consumed each of two diets in a cross-over design. The diets were comprised of identical natural foods with 30% of the calories as either sucrose or cooked wheat starch. Carbohydrate, fat and protein supplied 43, 42, and 15% of the calories, respectively. Of the calories 10% were eaten at breakfast (7:00 to 8:30 AM) and 90% at dinner (4:30 to 6:30 PM). Initial body weights were essentially maintained. Total serum lipids, triglycerides, and total cholesterol levels were significantly higher when the subjects consumed the sucrose diet than when they consumed the starch diet. Increases associated with the sucrose diet were greatest for triglycerides (33.0%). In a subgroup of nine subjects with triglyceride levels above the normal range, sucrose feeding increased triglyceride levels 45.2%. Triglycerides and pre-beta lipoproteins were significantly higher in males than in females. Pre-beta lipoproteins were 32% higher when the subjects consumed sucrose than when they consumed starch. For alpha and beta lipoproteins, small, nonsignificant increases were associated with sucrose feeding. Serum free fatty acids were not affected by diet. These results indicate that the consumption of sucrose can increase blood lipids that are considered to be risk factors in heart disease and that males and carbohydrate-sensitive individuals may be more susceptible than others to the effects of sucrose.

Effects of sugars on indices of glucose tolerance in humans.

Ten men and nine women were studied to determine whether replacement of utilizable complex carbohydrate by sugars (mono- and disaccharides) in a high-fiber, low-saturated fat diet would affect indices of glucose tolerance. Diets differed in that the 50% of calories derived from carbohydrate was either 35% complex and 15% sugars (low-sugar) on 15% complex and 35% sugars (high-sugar). Summation of glucose responses 30-180 min following an oral glucose tolerance test was significantly higher in men, but not women, after they consumed the high-sugar diet. Corresponding insulin responses were significantly higher in men consuming the high-sugar compared to the low-sugar diet. Insulin binding was significantly lower during the base line period and after the high-sugar diet compared to the low-sugar diet. Results indicate that sugars adversely affect indices of glucose tolerance when they replace complex carbohydrates even in a high-fiber, low-saturated fat diet.

Day-long glucose, insulin, and fructose responses of hyperinsulinemic and nonhyperinsulinemic men adapted to diets containing either fructose or high-amylose cornstarch.

Ten hyperinsulinemic and 11 nonhyperinsulinemic men consumed a typical American diet containing 20% of calories either as fructose or as high-amylose cornstarch for 5 wk in a crossover design to determine their effects on indices of glucose tolerance. Blood glucose, insulin, and fructose were determined before and 30, 60, 90, 120 and 180 min after breakfast, lunch, and dinner. Glucose responses were significantly lower 60 and 120 min and the insulin response lower 60 min after the meals containing fructose. Hyperinsulinemic men showed a tendency toward decreased insulin sensitivity after consuming fructose on the basis of an increased insulin-to-glucose ratio and decreased insulin binding to erythrocytes. These results generally show a beneficial effect of fructose on glucose tolerance; however, recommendations for including large amounts of fructose in the diet should also be based on a complete evaluation of the effect on other metabolic risk factors.

A study on Asian Indian and American vegetarians: indications of a racial predisposition to glucose intolerance.

Sixty-two Asian Indian and American vegetarians participated in a 3-h glucose tolerance test after an overnight fast to study clinical indices of glucose homeostasis. The Asian Indians had a higher (p less than 0.0035) insulinogenic score than the Americans. The Asian Indians had significantly higher insulin levels than the Americans at every sampling time during the glucose tolerance test except for the 3-h sample. The Indian men had significantly higher (p less than 0.05) plasma glucose than the other three groups at 2 h after the glucose load. American subjects had higher (p less than 0.0008) insulin binding to erythrocytes than the Asian Indian subjects. Scatchard analysis and competition-inhibition plots of the insulin-receptor data indicated that decreased binding in the Indian group results from a lowered number and decreased affinity of erythrocyte receptors. These results suggest that Asian Indians exhibit several clinical indications associated with an increased risk for the development of insulin-independent diabetes.

Blood lipids, lipoproteins, apoproteins, and uric acid in men fed diets containing fructose or high-amylose cornstarch.

Ten hyperinsulinemic and 11 nonhyperinsulinemic men consumed for 5 wk each in a cross-over design a diet, similar to one currently consumed in the United States, with 20% of the kilocalories from either fructose or high-amylose cornstarch to determine the effects of the two diets on various blood metabolites considered to be risk factors associated with heart disease. In the hyperinsulinemic men the intake of fructose as compared with cornstarch significantly increased total triglycerides and their lipoprotein distribution; total and very-low-density lipoprotein cholesterol; apoproteins B-100, C-II, C-III; and uric acid. In the nonhyperinsulinemic men total triglycerides, total and low-density lipoprotein cholesterol and uric acid were significantly greater after the consumption of fructose than after cornstarch. The results indicate that in a diet high in saturated fatty acids and cholesterol, fructose increases the levels of risk factors associated with heart disease, especially in hyperinsulinemic men.

Moderate diet control in children: the effects on metabolic indicators that predict obesity-related degenerative diseases.

Nine prepubertal obese boys ages 9 1/2 to 12 yr followed moderately restricted diets and moderate exercise routine for 31 wk. Foods were selected from the family's basic diet and the physical activities were tailored to the home environment. This dietary (approximate decrease of 600 kcal/day) and activity (approximate increase of 300 kcal/day) intervention program was sufficient to stop weight gain and normalize key metabolic indices for prediction of atherosclerosis, hypertension, and diabetes. Throughout the treatment period serum lipid responses included significantly lower (p less than 0.05) total cholesterol, low-density lipoprotein-cholesterol and triglycerides. High-density lipoprotein-cholesterol was constant throughout the period. Responses in carbohydrate metabolism included significantly lower (p less than 0.05) fasting insulin and glucose. Insulin and glucose levels were positively correlated with total caloric consumption and insulin was also positively correlated with sucrose consumption (p less than 0.05). Fasting insulin/glucose ratios and glycosylated Hb decreased throughout the treatment period, but serum glucagon levels remained constant. In response to a glucose load, insulin and glucose decreased significantly by wk 31 of treatment. A practical approach for normalizing metabolism in obese male children is presented.

Serum insulin and glucose in hyperinsulinemic subjects fed three different levels of sucrose.

Twenty-four adult men and women, classified as carbohydrate-sensitive on the basis of an exaggerated insulin response to a sucrose load, consumed diets containing 5, 18, and 33% of calories as sucrose for 6 wk each in a cross-over design. The diets contained identical natural and processed foods except for a patty containing 2, 15, or 30% of the calories as sucrose at the expense of wheat starch. Carbohydrate, fat, and protein provided 44, 42, and 14% of the calories, respectively. Of total calories, 25% were consumed at breakfast and 75% at dinner. Initial body weights of the subjects were essentially maintained. Fasting serum insulin levels increased with the sucrose content of the diet and were significantly higher in men than in women. Mean fasting glucose was significantly higher on either 18 or 33% sucrose than on 5% sucrose. The sucrose content of the diet did not affect fasting serum glucagon. When compared to the insulin response to a sucrose load (2 g/kg body weight) after consuming the 5% sucrose diet, serum insulin was significantly higher at 1 h after the 18% sucrose diet and at 0.5, 1, 2, and 3 h after the 33% sucrose diet. Except after 2 h, the glucose response was significantly greater after the 18 and 33% sucrose diets than after the 5% sucrose diet. These results indicate that sucrose intake by carbohydrate-sensitive individuals, even at levels approximating the average United States intake, can produce undesirable changes in several parameters associated with glucose tolerance.