A review of tobacco BY-2 cells as an excellent system to study the synthesis and function of sterols and other isoprenoids

In plants, two pathways are utilized for the synthesis of isopentenyl diphosphate (IPP), the universal precursor for isoprenoid biosynthesis. In this paper we review findings and observations made primarily with tobacco BY-2 cells (TBY-2), which have proven to be an excellent system in which to study the two biosynthetic pathways. A major advantage of these cells as an experimental system is their ability to readily take up specific inhibitors and stably- and/or radiolabeled precursors. This permits the functional elucidation of the role of isoprenoid end products and intermediates. Because TBY-2 cells undergo rapid cell division and can be synchronized within the cell cycle, they constitute a highly suitable test system for determination of those isoprenoids and intermediates that act as cell cycle inhibitors, thus giving an indication of which branches of the isoprenoid pathway are essential. Through chemical complementation, and use of precursors, intracellular compartmentation can be elucidated, as well as the extent to which the plastidial and cytoslic pathways contribute to the syntheses of specific groups of isoprenoids (e.g., sterols) via exchange of intermediates across membranes. These topics are discussed in the context of the pertinent literature.     

Technical note: Comparison of chromatographic profile of glycomacropeptide from cheese whey isolated using different methods

Glycomacropeptide (GMP) has heterogeneous carbohydrates, and this attributes to its various biological activities. In this study, we compared the chromatographic profiles of GMP isolated by three methods (trichloracetic acid fractionation, ethanol precipitation, and ultrafiltration) from whey protein isolate (WPI). Seven sharp heterogeneous GMP peaks were eluted from GMP prepared by ethanol precipitation and ultrafiltration using Mono Q anionic chromatography, while only 5 peaks were seen in TCA treated sample. The TCA pretreatment recovered only sialo-GMP (glycosylated) and eliminated all contaminated proteins; however, the recovery rate was the lowest (6.7% of the initial WPI). Ethanol precipitation recovered 20.4% of GMP from WPI and 75.7% was glycosylated, but the heating process might lead to degradation of glycosidic residues. Ultrafiltration was found to be the most effective in recovering GMP. The recovery rate was 33.9% with 81.6% sialo-GMP. We concluded that carbohydrate profile of GMP varied widely and depended on the isolation method. Based on the high recovery of sialo-GMP, the combination of ultrafiltration and anionic chromatography might be a suitable and practical approach on an industrial scale.     

Lean adolescents with increased risk for metabolic syndrome

The aim of the present study was to determine in adolescents the relationship between insulin levels and body mass index (BMI), body fat distribution, diet, life style and lipid profile. We studied 167 adolescents (68 boys and 99 girls) whose ages ranged from 14 to 17 years. A detailed medical (including pubertal stage) and nutritional record was obtained from each subject. Biochemical measurements included fasting serum insulin, glucose, total cholesterol (TC), triglycerides (Tg), HDL-C, LDL-C and VLDL-C. HOMA insulin resistance (IR) and HOMA beta-cell function (beta-cell) were calculated. Insulin levels were over 84 pmol/L (cut off normal value in our lab) in 56% of the boys and 43% of the girls. Thirty-seven percent of lean adolescents whose BMI was 21.5 +/- 1.9 kg/m2 presented higher fasting insulin levels. HOMA IR, Tg, systolic (SBP) and diastolic blood pressure (DBP) values when compared to a lean normoinsulinemic group. Insulin levels were correlated (p < 0.01) with body mass index. Both boys and girls in the highest BMI quartile (BMI > 24 kg/m2) had significantly higher serum insulin, HOMA beta-cell, and Tg levels, and the lowest HDL-C levels. A high-energy intake rich in saturated fat and low physical activity were found in this lean but metabolically altered adolescents. We conclude that even with a BMI as low as 21 kg/m2 an inappropriate diet and low physical activity might be responsible for the high insulin levels and dislipidemias in adolescents.     

Prevalence of nutritional deficiencies in Mexican adolescent women with early and late prenatal care

The objective was to evaluate the prevalence of specific nutritional deficiencies in a group of pregnant adolescents according to the gestational age when they started to receive prenatal care. A group of 163 pregnant adolescents that attended the Instituto Nacional de Perinatología (Mexico City) for the first time to receive prenatal care was evaluated. An anthropometrical evaluation was performed and a blood sample taken to determine hemoglobin, ferritin, erythrocyte folate and plasma zinc to all cases. The mean age was 15 years (11 to 17 years). The mean gestational age when starting prenatal care was 27 +/- 7 gestation weeks and most of them tended to have low weight (97 +/- 12% expected weight for height and gestational age). Eight of every ten adolescents had anemia and iron deficiency. Late prenatal care (> or = 25 weeks) was associated with the risk of presenting anemia OR 5.11 (CI 95% 2.4-10.7) iron deficiency (OR 3.5; CI 95% 1.7 to 7.1) and zinc deficiency (OR 2.9; CI 95% 1.1 a 7.6). In relation to folate deficiency, the opposite effect was observed (OR 0.10; CI 95% 0.02 a 0.48). Lack of opportune prenatal care was associated with the presence of iron and zinc depletion. Probably iron deficiency contributes to an erythrocyte folate accumulation.     

Nonalcoholic components in wine reduce low density lipoprotein cholesterol in normocholesterolemic rats

Using an experimental model that enables the effects of alcohol to be distinguished from the effects of the nonalcoholic components present in wine, we determined whether wine has effects other than those of alcohol on the metabolism of cholesterol. Male rats were fed a standard diet and had free access to water and either wine or an equivalent alcohol solution for 45 d or 6 mon. Alcohol intake was similar in the two groups of animals. Consumption of the alcohol solution or wine did not influence plasma cholesterol or high density lipoprotein-cholesterol. At 45 d, the consumption both of wine and of alcohol solution reduced low density lipoprotein (LDL)-cholesterol and very low density lipoprotein cholesterol. At 6 mon, only the rats that consumed wine had reduced LDL-cholesterol. After 45 d of consuming alcohol solution, total cholesterol in the aorta was significantly increased mainly as a result of the rise in free cholesterol. In the aorta, the effect of wine consumption was similar to the effect of alcohol solution consumption, although it was less intense. The only clear effect that could be ascribed to the nonalcoholic components in wine was that the LDL-cholesterol was reduced in the long term, although aortic cholesterol was not.     

Use of the urinary calcium/creatinine ratio as an indicator of the nutritional status of calcium

The relationship between calcium and creatinine in basal urine for evaluating its usefulness as an indicator of calcium nutritional status was evaluated. Samples of basal urine were collected form a group of 5 to 12-year-old school children who followed a three-month program of dietary complementation. The calcium to creatinine ratio showed no correlation with daily total calcium intake. However, a correlation was found when intake was expressed in mg per kg of body weight (r = 0.67) and increased significantly when data were grouped according to growth rate (r = 0.85). On this basis, the Ca/Creat. ratio was analyzed as a function of weight gain (g/kg) for calcium intake: higher and lower than 10 mg/kg/day (4 = 0.82 and 0.89, respectively), the intercept of each line with the Y axis (null weight gain) being 0.096 and 0.068, respectively. These findings indicate the possibility of using the Ca/Creat. ratio in field studies as an indicator of nutritional status of the population in regard to calcium.     

Approximations for Maximum Transportation with Permutable Supply Vector and Other Capacitated Star Packing Problems

We describe approximation algorithms for the maximum transportation with permutable supply vector and related problems.     

Rhythmical behavior in infancy: An ethological perspective.

Proposes that infants' rhythmical stereotypies (RS) are a developmental manifestation of intrinsic central motor programs that provide the temporal substrata for coordinated movements. RS function as nonspecific motor responses to a wide variety of eliciting stimuli, but may also become instrumental behavior used for communication, object manipulation, and self-stimulation. RS are likely to be phylogenetically old neuromuscular coordinations used by humans as adaptive behaviors, because slow cortical maturation results in long stages where voluntary movements have not fully matured. The relationship between normal infant RS and analogous behavior in abnormal groups and in nonhuman primates is discussed. (3 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

START-UP TIME IN TUBULAR REACTORS WITH AXIAL DISPERSION

In the modeling of nonideal reactors the axial dispersion model is one of the most used (Butt, 1980). Boundary conditions for a tubular reactor with axial dispersion were extensively analyzed (Danckwerts, 1953, Wehner and Wilhelm, 1965, Van Cauwen-berghe, 1966, Choi and Perlmutter, 1976, Deckwer and Mahlmann, 1976) Similarly, the steady state behaviour of the reactor when simple or complex reactions take place was also studied by several authors (Deckwer et al. 1972, Wan and Ziegler, 1973). However, the transient behaviour was only analyzed for simple kinetics expressions (Fan and Ahn, 1963, Sawinsky artd Hunek, 1977, Godslave and Chang, 1980)

In the present work, the time necessary to reach the steady state or start-up time is determined for single and complex reversible reactions. The analysis presented is also valid in case there is a change in feed concentration (feed upset, etc.)     

Volunteering in times of community crises: An integration within Caplan's theory of support systems.

Community work done during a period of national crisis, the October 1973 War in Israel, led to some assumptions about the mental implications of volunteering. It appeared to be a "natural phenomenon" at a point at which a community was hit by a disaster in which both those helping and those being helped derived mental health benefits. Within Caplan's theory of Support Systems (1974) volunteeering is considered a phenomenon that can be "mimicked", as avenues for mental health intervention are sought for populations hit by a disaster. The issue of how to best utilize the services of volunteers is raised as the phenomenon appears to proceed through different phases. Following Caplan's (1974) distinction between two types of informal care-givers, the "generalist" and the "specificist", this paper suggests that volunteers should be differently used at specific phases of crises, in order to have mental health benefits for both helpers and those being helped. (PsycINFO Database Record (c) 2010 APA, all rights reserved)