Structural and evolutionary characteristics of pyruvate phosphate dikinase in Giardia lamblia and other amitochondriate protozoa / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pyruvate phosphate dikinase (PPDK) reversibly catalyzes the interconversion of phosphoenolpyruvate (PEP) and pyruvic acid, leading to catabolism and adenosine triphosphate (ATP) synthesis or gluconeogenesis and ATP consumption. Molecular modeling of PPDKs from divergent organisms demonstrates that the orientation of the phosphorylatable histidine residue within the central domain of PPDK determines whether this enzyme promotes catabolism or gluconeogenesis. The goal of this study was to determine whether PDDK from Giardia underwent adaptive evolution in order to produce more energy under anaerobic conditions.</p><p><b>METHODS</b>A total of 123 PPDK sequences from protozoans, proteobacteria, plants, and algae were selected, based upon sequence similarities to Giardia lamblia PPDK and Zea mays PPDK. Three-dimensional (3-D) models were generated for PPDKs from divergent organisms and were used to compare the orientation of the phosphorylatable histidine residue within the central domain of PPDKs. These PPDKs were compared using a maximum-likelihood tree.</p><p><b>RESULTS</b>For PPDK from Giardia, as well as from other anaerobic protozoans, the central domain tilted toward the N-terminal nucleotide-binding domain, indicating that this enzyme catalyzed ATP synthesis. Furthermore, the orientation of this central domain was determined by interactions between the N- and C-terminal domains. Phylogenetic analysis of the N- and C-terminal sequences of PPDKs from different species suggested that PPDK has likely undergone adaptive evolution in response to differences in environmental and metabolic conditions.</p><p><b>CONCLUSION</b>These results suggested that PPDK in anaerobic organisms is functionally adapted to generate energy more efficiently in an anaerobic environment.</p>

Application of Nutritional Risk Screening 2002 in the investigation of nutritional risks, undernutrition, and nutritional support among inpatients in tertiary hospitals in Tianjin / 中华临床营养杂志

Objective To investigate the nutritional risks, undernutrition, and nutritional support among inpatients in tertiary hospitals in Tianjin using Nutritional Risk Screening 2002 (NRS2002). Methods Inpatients in six departments in two tertiary hospitals in Tianjin (Tianjin Nankai Hospital and Tianjin Chest Hospital ) were consecutively enrolled from March 2005 to March 2006. Their nutritional risks were screened using NRS 2002, and the nutritional support was investigated. Results A total of 1200 inpatients received nutritional screening, and 93.0% of them underwent NRS 2002 scoring. The prevalence of undernutrition was 9. 8% and the prevalence of nutritional risk was 42. 8%. Of these patients, 241 patients (46.4%) with NRS2002≥3 received nutrition support, and 244 patients (35.9%) with NRS2002 ＜3 received nutritional support Conclusions NRS2002 is suitable for nutritional risk screening among inpatients. Inpatients usually have nutritional risks or undernutrition. However, physicians at different levels in different regions have different awareness of such risks or conditions, and the clinical application of nutritional supports sometimes are inappropriate.