Biosynthesis and Application of Sugar Nucleotides / 生物化学与生物物理进展

Glycosylation is one of the most important reactions in living organisms as it results in the formation of glycoconjugates with diverse biological functions. Sugar nucleotides are structurally composed of sugar and nucleoside diphosphate or monophosphate, which are widespread within a variety of biological cells. As glycosyl donors for the transglycosyl reactions catalyzed by Leloir-type glycosyltransferases, sugar nucleotides are essential for the synthesis of glycans and glycoconjugates. However, high costs and limited availability of nucleotide sugars prevent applications of biocatalytic cascades on an industrial scale. Therefore, attentions on synthetic strategies of sugar nucleotides have been increasing to achieve their wide applications in various fields. The 9 common sugar nucleotides in mammals have been fully studied with large-scale synthesis through chemical, enzymatic (chemo-enzymatic) and cell factory strategies. In addition to common sugar nucleotides, many rare sugar nucleotides are present in plants and bacteria. Although unnatural sugar nucleotides cannot be synthesized in organisms, they have great potential in research as substrates for glycosyltransferases in carbohydrate synthesis, as enzyme inhibitors in biochemical studies, and as components of glycoconjugate biosynthesis. Therefore, increasing attention has been paid to explore the efficient synthesis of unnatural sugar nucleotides. Currently, strategies for chemical synthesis of sugar nucleotides have been greatly improved, such as the use of effective catalysts for forming pyrophosphate bonds and the development of entirely new synthesis protocols. Multiple sugar nucleotides, especially unnatural sugar nucleotides, are synthesized chemically. However, chemical synthesis requires tedious protection and deprotection steps, resulting in complex steps, high cost and low yield. In contrast, enzymatic (chemo-enzymatic) and cell factory methods have significant advantages such as high yield, easy operation and easy process scale-up in the preparation of sugar nucleotides. Hence, they are prominent strategies for sugar nucleotide preparation. Herein, the biosynthesis and application of sugar nucleotides are reviewed, mainly focusing on the 9 sugar nucleotides common in mammals. The early strategies for enzymatic synthesis of sugar nucleotides generally used de novo synthesis pathway. With the discoveries of enzymes involved in salvage pathway of sugar nucleotide synthesis and the development of one-pot multienzyme (OPME) method, the synthesis of sugar nucleotides was greatly simplified. Cell factory method employs the microbial living cells as a “processing plant” by engineering their metabolic pathways through genetic engineering technology. The cell factory method has high yield, and has been applied for efficient synthesis of several sugar nucleotides. Moreover, the strategy of gram-scale synthesis of multiple rare sugar nucleotides by cascade reactions from common sugar nucleotides using sugar nucleotides synthases cloned from different sources was illustrated. In recent years, the synthesis cost of sugar nucleotides has been further reduced through various ways, such as regeneration of nucleotides, regeneration of organic cofactors, and application of immobilized enzyme technology. Furthermore, through the continuous improvement of sugar nucleotide purification process, the use of high concentration of multi-enzyme cascade and rapid non-chromatographic purification process, the synthesis of multiple sugar nucleotides and their derivatives from monosaccharides was achieved, which gradually broke the limitations of the existing strategy. With the efficient synthesis of sugar nucleotides, their applications in various fields have been increasingly explored, including the synthesis of glycans and glycoconjugates, biochemical characterization of glycosyltransferases and bioorthogonal labeling strategies, which are of great significance to the research of biochemistry, glycobiology and the development of related pharmaceutical products.

Systemic lupus erythematosus with primary sclerosing cholangitis / 中华风湿病学杂志

Objective:To investigate the clinical manifestations, laboratory and imaging features, treatment and prognosis of systemic lupus erythematosus (SLE) with primary sclerosing cholangitis (PSC).Methods:This is a retrospective case series study describing the clinical, laboratory and imaging manife-stations, treatment and prognosis of 3 SLE patients with PSC. The related literatures were reviewed.Results:In total, 10 patients were included. SLE with PSC, with an average age of (43±17) years old, was more common with hematological and renal involvement, jaundice and arthralgia, positive anti-double-stranded DNA (anti-dsDNA) antibody, hypocomplementemia, elevated erythrocyte sedimentation rate (ESR) and abnormal liver function with predominately elevated alkaline phosphatase (ALP). The classic magnetic resonance cholangio-pancreatography (MRCP) features of PSC include multifocal strictures, beading and areas of dilatation involving the intra- and/or extrahepatic bile ducts. The treatment included glucocorticosteroids, immunosup-pressants and ursodeoxycholic acid (UDCA), and some patients required biliary drainage. Most patients had a good prognosis.Conclusion:Although PSC is rare, attention should be paid to SLE patients with abnormal liver function, especially with elevated ALP, in order to differentiate from PSC.

Case series and clinical analysis of 14 cases of catastrophic antiphospholipid syndrome / 北京大学学报(医学版)

OBJECTIVE@#Catastrophic antiphospholipid syndrome (CAPS), also known as Asherson's syndrome, is a special subtype of antiphospholipid syndrome (APS) characterized by multiple intravascular thrombosis involving multiple organs systems or tissues simultaneously or continuously, high titer antiphospholipid antibodies and high mortality rate. This article's aims was to analyze the clinical manifestation, laboratory examination and treatment therapy of CAPS for the purpose of improving the understanding, diagnosis and treatment of the disease in clinical practice.@*METHODS@#Retrospective analysis and descriptive statistics were applied to the clinical manifestations and laboratory findings of 14 CAPS cases from APS Shanghai Database (APS-SH) with catastrophic antiphospholipid.@*RESULTS@#Of the 14 CAPS patients, 12 cases satisfied the 2003 CAPS Classification Criteria accepted in the 10th International Congress on Antiphospholipid Antibody, and were diagnosed as definite APS and 2 cases were diagnosed as probable CAPS. Three cases were categorized as primary APS and 11 as APS secondary to systemic lupus erythematosus (SLE). Infection was mostly commonly seen before the onset of CAPS, followed by SLE activity and surgery. Among the involved organs, systems and tissues, brain and lung were most commonly affected sites of arterial thrombosis while peripheral vein was most commonly affected in venous thrombosis events among the clinical events. Triple positivity of anticardiolipin antibody (aCL), anti-β2 glyeoprotein I antibody (aβ2GPI), lupus anticoagulant (LA) were detected in 54.55% of the patients. Thrombocytopenia and decreased hemoglobin were frequently seen in the CAPS patients, and the majority proved to be hemolytic anemia. Of all the cases, 6 ended with death. The triple therapy strategy (anticoagulants, glucocorticoid, intravenous immunoglobulin and/or plasma exchange) could help to improve prognosis, cyclophosphamide and rituximab might benefit the patients with other comorbidities such as SLE and micro-angiopathic hemolytic anemia (MHA).@*CONCLUSION@#CAPS patients suffer from life-threatening acute multiple small vessel thrombosis with high titer of antiphospholipid antibody, potentially leading to multiple organ failure and a poor prognosis, thus early diagnosis and sufficient treatment are critical to prevent the progression of disease and improve the prognosis.

Effect of visfatin on the structure and immune levels in the small intestine of LPS-induced rats / Efecto de la visfatina sobre la estructura y los niveles de inmunidad en el intestino delgado de ratas inducidas por lipopolisacáridos

This study investigated the effects of visfatin on the structure and the immunity levels in the small intestine of LPS-induced rats. Forty Wistar male and female SPF rats were randomly and equally divided into four groups: the saline (control), vistfatin, lipopolysaccharide (LPS), and visfatin+LPS co-stimulated. The functions of visfatin in the intestinal mucosal immunity were investigated by examining the variation of tissue structure, inflammation and immunity-related proteins in the intestine of immunologically stressed rats using HE staining, ELISA, immunohistochemistry and Western Blot. The results showed that, when compared with the control group, the visfatin-treated group showed a decrease in the intestinal villus height and width, and a significant increase in the levels of IL-6 and TNF-ð as well as Immunoglobulin A (IgA) positive cells. Additionally, when compared with the LPS-treated group, the visfatin+LPS co-stimulated group showed a decrease in the villus height and width as well as the levels of IL-6 and TNF-ð, and an increase in IgA levels, implying a shrinking response to LPS injection. All the results suggest that, under normal physiological conditions, visfatin disturbs the body's homeostasis and causes intestinal villus atrophy by increasing IgA expression. While under immune response conditions, LPS acts as an exogenous antigen to promote visfatin against LPS-induced inflammation by decreasing the expression of IgA. Under immune stress conditions, visfatin as an exogenous stimulus promotes the immune response by regulating the protein levels of IL-6, TNF-ð and IgA.

Este estudio investigó los efectos de la visfatina sobre la estructura y los niveles de inmunidad en el intestino delgado de ratas inducidas por lipopolisacáridos (LPS). Cuarenta ratas Wistar se dividieron aleatoriamente e igualmente en cuatro grupos: solución salina (control), vistafin, LPS y visfatina + LPS co-estimuladas. Las funciones de la visfatina en la inmunidad de la mucosa intestinal se investigaron mediante el examen de variación de la estructura del tejido, la inflamación y las proteínas relacionadas con la inmunidad en el intestino de ratas estresadas inmunológicamente; usando tinción HE, ELISA, inmunohistoquímica y Western Blot. Los resultados mostraron que, en comparación con el grupo control, el grupo tratado con visfatina presentó una disminución en la altura y ancho de las vellosidades intestinales, y un aumento significativo en los niveles de IL-6 y TNF-ð, así como inmunoglobulina A (IgA células positivas). Además, al comparar este grupo con el grupo tratado con LPS- el grupo visfatina + LPS co-estimulado mostró una disminución en la altura y ancho de las vellosidades, así como en los niveles de IL-6 y TNF-ð, y un aumento en los niveles de IgA, lo que implica reducción de una respuesta a la inyección LPS. Todos los resultados sugieren que, en condiciones fisiológicas normales, la visfatina perturba la homeostasis del cuerpo y provoca la atrofia de las vellosidades intestinales mediante el aumento de la expresión de IgA. Mientras que bajo condiciones de la respuesta inmune, LPS actúa como un antígeno exógeno para promover visfatina contra la inflamación inducida por LPS por la disminución de la expresión de IgA. En condiciones de estrés inmunológico, la visfatina como estímulo exógeno promueve la respuesta inmune mediante la regulación de los niveles de proteína de IL-6, TNF-ð e IgA.

Study on influencing factors of professional commitment of student nurses based on theory of role stress / 中国实用护理杂志

Objective To investigate the level of professional commitment of student nurses,and explore the impact of student nurses' role conflict and role ambiguity on their professional commitment.Methods From May to June 2014,totally 320 student nurses from a third-level hospital in Tianjin were recruited in this study.And Role Stress Scale and Nursing Professional Commitment Scale were used in the investigation.Results The total score of role stress of student nurses was (44.29±5.53) scores,and the total score of professional commitment of student nurses was (86.12±14.14) scores.Pearson correlation analysis and multiple linear regression analysis showed that student nurses' role conflict was positively correlated with professional commitment,but their role ambiguity was negatively correlated with professional commitment.Conclusion School and hospital managers should adopt effective measures to relieve student nurses' role ambiguity and guide the correct understanding of role conflict to maintain a stable nursing team.

Biochemical changes in striatum of Parkinson's disease rat model observed by modified proton magnetic resonance spectroscopy / 生物医学工程学杂志

This study was undertaken to observe the biochemical changes in striatum of Parkinson's disease (PD) rat model by modified proton magnetic resonance spectroscopy. 12 SD rats were divided into model (n=7) and control (n=5) groups. At 3 weeks after the injection of 6-hydroxydopamine into right striatum, 1H-MRS on the striatum was taken by modified proton magnetic resonance spectroscopy, and then tyrosine hydroxylase (TH) immunostatining was used to visualize the changes of the neurons in substantia nigra and neurites in striatum. The results showed that TH positive neurons and neurites in the substantia nigra compacts (SNc) and striatum in the normal side of the rat model of PD were decreased (P < 0.05), which proved the successful establishment of PD models. The NAA/Cr ratio of the injected side striatum of model group was lower than that of the normal side (P < 0.05). The ratios of Cho/Cr showed no significant difference between the two sides (P > 0.05). These results indicated that the modified 1.5T 1H-MRS should be a noninvasive technique which could provide useful information about the biochemical metabolites in striatum for the study of PD in rat model.

Clinical and radiologic study in Marchiafava-Bignami disease / 中华神经医学杂志

Objective To investigate the clillicoradiologic characteristics of MarchiafavaBignami disease (MBD). Methods The clinical and neuroimaging findings, including lesion morphorogy, distribution, signal intensity/density in 7 MBD patients were retmspectiVely analyzed.Diffusion-weighted imaging(DWI)was performed in 5 cases.Of the 7 cases,4 underwent both CT and MRI,2 only CT and 1 MRI. Results with extensive iso-or slightly hypo-intensity on T1-weighted images and hyper-intensity on T2-weighted images, 5 patients were manifested as acute onset, in which white matter (WM) was symmetrically involved in bilateral periventricular and frontal subconical regions. Punctate or linear hypo-intensity on FLAIR images was found in the atrophied corpus callosum in 1 case presented as chronic type, with scattered patchy hyper-intensity in periventricular WM and frontal subcortical WM. DWI showed markedly hyper-intensity with diffusion restriction in 2 cases in acute phase with apparent diffusion coefficient(ADC)values(0.52～0.55)×10-3 mm2/s.Brain atrophy was found in all the 7 patients. Conclusions The MRI features of MBD are characteristic and may be associated with the clinical spectrum and prognosis.

Correlation of serum interleukin-6 and interleukin-18 levels to carotid artery intimal-medial thickness in patients with acute cerebral infarction / 中华神经医学杂志

Objective To investigate the correlation of serum interleukin-6 (IL-6) and IL-18levels to carotid artery intimal-medial thickness (IMT) in patients with acute cerebral infarction (ACI).Methods In 64 patients with ACI and 30 healthy volunteers, serum IL-6 and IL-18 levels were detectedusing radioimmunoassay and enzyme-linked immunosorbent assay (ELISA), respectively. Carotid arteryIMT were measured in the two groups using color Doppler ultrasound, and the ACI patients were dividedinto two groups with carotid IMT greater or lower than 1.0 mm. Results The ACI patients and thehealthy volunteers showed significant differences in serum IL-6 (P<0.05) and IL-18 levels (P<0.05),which were also significantly different between ACI patients with carotid IMT ≥ 1.0 mm and those withIMT<1.0 mm (P<0.05). The ACI patients with IMT<1.0 mm had comparable serum IL-6 and IL-18 levelsto those in the healthy volunteers. In patients with carotid IMT ≥ 1.0 mm, the serum IL-18 level waspositively correlated to IMT (r=0.549, P=0.001), but the IL-6 level was not related to IMT (P>0.05).Conclusion The serum levels of IL-6 and IL-18 are elevated in ACI patients with increased carotid IMT.

Regularity of sugar-uptake in human red blood cells / 中国实验血液学杂志

Lyophilization of human red blood cells has important significance in clinical application. Some sugars, especially trehalose, can be more tolerant of some organism or cells to dry environments, But, how to bring sugars into cells is a challenge. This study was aimed to investigate the regularity of sugar-uptake in human red blood cells. The absorption rate of trehalose and glucose in red blood cells, free hemoglobin level and erythrocyte deformation index were determined at different incubation temperature (4, 25 and 37 degrees C), different sugar concentration (0, 0.2, 0.4, 0.6, 0.8 and 1 mol/L) and different incubation time (1, 3, 5, 7 and 9 hours). The results showed that with increase of temperature and extracellular sugar concentration, the uptake of sugar in red blood cells also increased, the intracellular trehalose and glucose concentrations were over 30 mmol/L and 40 mmol/L respectively. The effects of incubation time on uptake of trehalose and glucose were different. With prolonging of incubation time, the uptake of trehalose showed firstly increase and then decrease, however, the uptake of glucose showed a constant increase. But the loading process had side-effect on free hemoglobin and maximum deformation index (MAXDI) of red blood cells, especially for trehalose, which mainly come from high osmotic pressure. It is concluded that the uptake of sugars in red blood cells is closely dependent on incubation temperature, extracellular sugar concentration and incubation time. In certain condition, the efficiency of sugar uptake is very high, but this process also damages red blood cells so as to affect the application of sugars in lyophilization of red blood cells. The research in the future should focus on how to deal with the relation between cell injury and uptake efficiency of sugar in red blood cells.