Structure and molecular interactions of a unique antitumor antibody specific for N-glycolyl GM3

N-glycolyl GM3 ganglioside is an attractive target antigen for cancer immunotherapy, because this epitope is a molecular marker of certain tumor cells and not expressed in normal human tissues. The murine monoclonal antibody 14F7 specifically recognizes N-glycolyl GM3 and shows no cross-reactivity with the abundant N-acetyl GM3 ganglioside, a close structural homologue of N-glycolyl GM3. Here, we report the crystal structure of the 14F7 Fab fragment at 2.5 A resolution and its molecular model with the saccharide moiety of N-glycolyl GM3, NeuGcalpha3Galbeta4Glcbeta. Fab 14F7 contains a very long CDR H3 loop, which divides the antigen-binding site of this antibody into two subsites. In the docking model, the saccharide ligand is bound to one of these subsites, formed solely by heavy chain residues. The discriminative feature of N-glycolyl GM3 versus N-acetyl GM3, its hydroxymethyl group, is positioned in a hydrophilic cavity, forming hydrogen bonds with the carboxyl group of Asp H52, the indole NH of Trp H33 and the hydroxyl group of Tyr H50. For the hydrophobic methyl group of N-acetyl GM3, this environment would not be favorable, explaining why the antibody specifically recognizes N-glycolyl GM3, but not N-acetyl GM3. Mutation of Asp H52 to hydrophobic residues of similar size completely abolished binding. Our model of the antibodycarbohydrate complex is consistent with binding data for several tested glycolipids as well as for a variety of 14F7 mutants with replaced VL domains.     

Structural and functional comparison between the stability systems ParD of plasmid R1 and Ccd of plasmid F

Summary The stability determined by the systems ParD of plasmid R1 and Ccd of plasmid F is due to the concerted action of two proteins, a cytotoxin and an antagonist of this function. In this paper we report that CcdA and Kis proteins, the antagonists of the Ccd and ParD systems respectively, share significant sequence homologies at both ends. In Kis, these regions seem to correspond to two different domains. Despite the structural similarities, Kis and CcdA are not interchangeable. In addition we have shown that the cytotoxins of these systems, the Kid and CcdB proteins, do not share structural homologies. In contrast to CcdB, the Kid protein of the ParD system induces RecA-dependent cleavage of the cl repressor of bacteriophage very inefficiently or not at all. The functional implications of these results are discussed.     

Partial purification and characterization of NADH-glutamate synthase from faba bean (Vicia faba) root nodules

The NADH-dependent glutamate synthase (EC 1.4.1.14) from the plant fraction of N₂-fixing faba bean (Vicia faba) nodules has been purified 74-fold to a specific activity of about 3 μmol min⁻¹ mg protein⁻¹ with a final yield of 32%. The NADH-GOGAT activity was associated with a single form of the enzyme that behaved as a monomeric protein with a subunit molecular weight of 195 kDa and a native molecular weight from 222 to 236 kDa estimated by gel filtration or PAGE, respectively. The NADH-GOGAT band on SDS-PAGE was cut out and used to produce antibodies. Western blots of SDS-PAGE of crude nodule proteins revealed a 195 kDa polypeptide in root extracts but not in those of leaves or bacteroids. The antiserum also cross-reacted with a polypeptide of camparable molecular weight (195 kDa) from both amide and ureide transporting species legume nodules, indicating that some antigenic epitopes have been conserved between nodule NADH-GOGAT of different species.     

Milox fractionation of empty fruit bunches from Elaeis guineensis

Milox pulping of EFB was used to obtain pulps. In the first Milox stage, the influences of operating variables on pulp properties were studied and polynomial and neural fuzzy models that reproduced the experimental results with errors less than 10% were developed. Operating variables were found (93 wt.% of formic acid, 3 wt.% of hydrogen peroxide, and 165 min) that yielded acceptable pulp properties (40.5% yield, 50.3% brightness and 608 mL/g viscosity) at reasonable chemical and energy costs. The second stage was studied by subjecting the liquors of the previously optimized first stage to different treatment times. This time should be 30 min or less, to avoid a negative effect on viscosity. The residual liquor from the first Milox stage contained virtually no precipitable lignin and only low amounts of sugar (wt.%): glucose 0.71, xylose 4.22, galactose 1.19, mannose 0.22, all on original raw material dry.     

Het verklaren van verschillen in ervaren kwaliteit van leven van kwetsbare ouderen: een ‘mixed-method’ onderzoek

Most research on (multidimensional) frailty focuses on deficits and risks of adverse outcomes. However, frail older people can still report positive outcomes, such as a relatively high QoL. In order to develop more positively oriented prevention strategies, this exploratory study aimed (a) to identify characteristics related to QoL among frail older people; and (b) to explain discrepancies between higher and lower levels of QoL, with a specific focus on strengths frail older people with a higher QoL still may have. Quantitative and qualitative data was gathered by means of semi-structured interviews with Flemish community-dwelling, frail older people with higher (n?=?16) and lower QoL levels (n?=?18). Quantitative analyses showed that frail older people with a higher QoL were older, had lower levels of psychological frailty, and reported higher meaning in life compared to those with a lower QoL. Outcomes of qualitative analysis showed that participants in the high QoL subgroup adapted more effectively to difficulties, had more things in prospect, performed more activities, and were more satisfied with their social network compared to the low QoL subgroup. To conclude, this exploratory study suggests possibilities to promote and improve QoL by strengthening specific resources among frail older people.Please note that an English version of this article has been published in BMC Geriatrics: van der Vorst A, Zijlstra GAR, De Witte N, Vogel RGM, Schols JMGA, Kempen GIJM, D?SCOPE Consortium. Explaining discrepancies in self-reported quality of life in frail older people: a mixed-methods study. BMC Geriatr. 2017;17(1): 251.  https://doi.org/10.1186/s12877-017-0641-y.     

Lifestyle factors and incident mobility limitation in obese and non-obese older adults

Objective: This study examines the association between incident mobility limitation and 4 lifestyle factors: smoking, alcohol intake, physical activity, and diet in well‐functioning obese (n = 667) and non‐obese (n = 2027) older adults. Research Methods and Procedures: Data were from men and women, 70 to 79 years of age from Pittsburgh, PA and Memphis, TN, participating in the Health, Aging and Body Composition (Health ABC) study. In addition to individual lifestyle practices, a high‐risk lifestyle score (0 to 4) was calculated indicating the total number of unhealthy lifestyle practices per person. Mobility limitation was defined as reported difficulty walking 1/4 mile or climbing 10 steps during two consecutive semiannual assessments over 6.5 years. Results: In non‐obese older persons, significant risk factors for incident mobility limitation after adjustment for socio‐demographics and health‐related variables were current and former smoking [hazard ratio (HR) = 1.51; 95% confidence interval (CI), 1.20 to 1.89; HR = 1.40; 95% CI, 1.12 to 1.74), former alcohol intake (HR = 1.30; 95% CI, 1.05 to 1.60), low and medium physical activity (HR = 1.78; 95% CI, 1.45 to 2.18; HR = 1.29, 95% CI, 1.07 to 1.54), and eating an unhealthy diet (HR = 1.57; 95% CI, 1.17 to 2.10). In the obese, only low physical activity was associated with a significantly increased risk of mobility limitation (HR = 1.44; 95% CI, 1.08 to 1.92). Having two or more unhealthy lifestyle factors was a strong predictor of mobility limitation in the non‐obese only (HR = 1.98; 95% CI, 1.61 to 2.43). Overall, obese persons had a significantly higher risk of mobility limitation compared with non‐obese persons, independent of lifestyle factors (HR = 1.73; 95% CI, 1.52 to 1.96). Conclusions: These results underscore the importance of a healthy lifestyle for maintaining function among non‐obese older adults. However, a healthy lifestyle cannot overcome the effect of obesity in obese older adults; this stresses the importance of preventing obesity to protect against mobility loss in older persons.     

Macronutrient content in leaves of bean plants (Phaseolus vulgaris,L.) grown with differents rates of N/S as fertilizers

Summary The effect of increasing rates of nitrogen (N) and sulphur (S) as fertilizers on the yield, leaf area and N, P, S, Ca, Mg, NO₃ ⁻ and SO₄ ⁼ content in leaves of bean (Phaseolus vulgaris, L.) were studied in a hydroponic culture experiment under greenhouse conditions. Bean plants responded significantly to all treatments with differents N/S ratios. When plants grew with high N/S ratios, the leaf content of N, Ca and NO₃ ⁻ increased while the content of K, P and SO₄ ⁼ decreased. However, optimal yield and leaf area were not obtained. Optimal leaf and fruit dry matter was obtained at N/S ratio value of 1.41. When lower N/S rates were used, optimal leaf and fruit dry matter was only observed when the leaf N/S ratio was between 15 and 16. At high sulphate levels in the nutrient solution there is no interaction with nitrate which is easily observed, resulting in an increase in yield. An interaction between nitrate and sulphate in the nutrient solution was found at a N/S ratio of 0.81 which produced in leaves a synergic effect between P-K, an antagonistic effect between N-P and N-K and a lower yield. This research was supported by Fundacion ‘Ramon Areces’.