Rational design of L-arabinose isomerase from Lactobacillus fermentum and its application in D-tagatose production / 生物工程学报

L-arabinose isomerase (L-AI) is the key enzyme that isomerizes D-galactose to D-tagatose. In this study, to improve the activity of L-arabinose isomerase on D-galactose and its conversion rate in biotransformation, an L-arabinose isomerase from Lactobacillus fermentum CGMCC2921 was recombinantly expressed and applied in biotransformation. Moreover, its substrate binding pocket was rationally designed to improve the affinity and catalytic activity on D-galactose. We show that the conversion of D-galactose by variant F279I was increased 1.4 times that of the wild-type enzyme. The Km and kcat values of the double mutant M185A/F279I obtained by superimposed mutation were 530.8 mmol/L and 19.9 s-1, respectively, and the catalytic efficiency was increased 8.2 times that of the wild type. When 400 g/L lactose was used as the substrate, the conversion rate of M185A/F279I reached a high level of 22.8%, which shows great application potential for the enzymatic production of tagatose from lactose.

Análisis comparativo de respuesta glicémica y de péptido C, tras la ingesta de estevia y D-tagatosa, según habitualidad de consumo de edulcorantes no nutritivos y preferencias alimentarias reportadas por mujeres con resistencia a la insulina / Comparative analysis of glicemic response and c peptide, after comsumption of stevia and d tagatosa, according to regular compsumtion of not nutritive sweeteners andnourish preferences reported by woman with insuline resistance

INTRODUCCIÓN: El consumo de edulcorantes no nutritivos (ENN) ha ido en aumento. A pesar de ello, se desconoce el efecto entre el consumo habitual de ENN y las preferencias alimentarias con parámetros bioquímicos en pacientes con resistencia a la insulina. OBJETIVO: Comparar la respuesta glicémica y de péptido C, según habitualidad de consumo de edulcorantes y preferencias alimentarias reportados por mujeres con resistencia a la insulina tras la ingesta de estevia y D-tagatosa. MÉTODOS: Treinta y tres mujeres con RI se sometieron a una encuesta de opción múltiple sobre preferencias alimentarias y ETCC modificada de edulcorantes. Aleatoriamente recibieron una precarga de control o experimental (estevia y D-tagatosa) donde se midió glicemia y péptido C en los tiempos -10, 30, 60, 90, 120, 180. RESULTADOS: Se encontró un ABC de péptido C más alto después de la ingesta de D-tagatosa (p = 0,02) en pacientes que prefieren alimentos ricos en proteínas en comparación con aquellos que prefieren alimentos ricos en grasas o en carbohidratos simples. Se observó un mayor ABC de péptido C (p = 0,04) para la prueba control en quienes prefieren el sabor salado y consumen menor cantidad de ENN, sin diferencias significativas entre quienes prefirieron sabor dulce. CONCLUSIONES: Al comparar las respuestas glicémicas e insulinémicas entre habitualidad de consumo de edulcorantes y preferencias alimentarias reportados por las pacientes tras la ingesta de agua, estevia y D-Tagatosa, no se obtuvieron diferencias significativas. Salvo en quienes preferían alimentos ricos en proteínas tras la ingesta de D- tagatosa y quienes preferían sabor salado con menor consumo habitual de ENN tras ingesta control.

INTRODUCTION: The consumption of non-nutritive sweeteners (NNS) has been increasing. Despite this, the effect between the habitual consumption of ENN and food preferences with biochemical parameters in patients with insulin resistance is unknown. OBJECTIVE: To compare the glycemic and C-peptide response, according to the habitual consumption of sweeteners and food preferences reported by women with insulin resistance after ingesting stevia and D-tagatose. METHODS: Thirty-three women with IR underwent a multiple choice survey on food preferences and modified ETCC for sweeteners. They randomly received a control or experimental preload (stevia and D-tagatose) where glycemia and peptide C were measured at times -10, 30, 60, 90, 120, 180. RESULTS: A higher C-peptide AUC was found after ingestion of D-tagatose (p = 0.02) in patients who prefer foods rich in protein compared to those who prefer foods rich in fat or simple carbohydrates. A higher AUC of peptide C (p = 0.04) is performed for the control test in those who prefer a salty taste and consume a lower amount of ENN, without significant differences between those who prefer a sweet taste. CONCLUSION: When comparing the glycerol and insulin responses between the habitual consumption of sweeteners and the food preferences reported by the patients after the ingestion of water, stevia and D-Tagatose, no significant differences were obtained. Except in those who prefer foods rich in protein after ingesting D-tagatose and those who prefer salty taste with less habitual consumption of NNS after control intake.

Efectos de la ingesta de los edulcorantes estevia y D-tagatosa sobre el metabolismo de la glucosa, ácido úrico y apetito-saciedad / Effects of stevia and D-tagatose sweeteners intake om glucose, uric acid metabolism and appetite-satiety

INTRODUCCIÓN: Si bien, los edulcorantes no nutritivos (ENN) estevia y D-tagatosa han sido reportados como seguros, han demostrado tener algunos efectos metabólicos tras su ingesta. OBJETIVO: Describir los efectos de la ingesta de estevia y D-tagatosa sobre el metabolismo de la glucosa y ácido úrico, y del apetito-saciedad, a partir de la evidencia disponible. MÉTODOS: Revisión descriptiva. Se realizó búsqueda en PubMed utilizando los siguientes términos y palabras clave: "stevia rebaudiana", "tagatose", "D-tagatose", "blood glucose", "insulin", "metabolic processes", "uric acid", "hyperuricemia", "appetite" o "satiety". El análisis de los estudios seleccionados fue discrecional. RESULTADOS: Existen estudios que demuestran efectos beneficiosos tras el consumo de estevia o D-tagatosa sobre el control glicémico, apetito y saciedad tanto en sujetos sanos como con alteraciones en el metabolismo de la glucosa. Por otra parte, un número importante de estudios que evalúan la ingesta de estevia reportan efectos nulos sobre dichos parámetros. En relación al ácido úrico, solo un estudio en sujetos con enfermedad renal crónica reporta aumento en la concentración de ácido úrico plasmático tras la ingesta de 500 mg/día de estevia. Pocos estudios han evaluado el efecto de la ingesta de D-tagatosa sobre uricemia, en sujetos sanos y diabéticos, reportando un aumento transitorio y significativo en los niveles de ácido úrico sérico, sin embargo, no se ha logrado demostrar un efecto hiperuricémico asociado. Es importante destacar que la metodología de los estudios revisados es heterogénea, especialmente en relación al tamaño muestral, tiempo, dosis y vía de adminitración del edulcorante. CONCLUSIÓN: La ingesta de estevia y D-tagatosa ha demostrado efectos beneficiosos sobre el metabolismo de la glucosa, el apetito y la saciedad. El efecto del consumo de D-tagatosa sobre ácido úrico sérico requiere mayor evidencia para demostrar su significancia clínica.

INTRODUCTION: No-nutritive sweeteners stevia and D-tagatose have been reported as safe according to their acceptable daily intake, however, they have been shown to have metabolic effects after their ingestion. OBJECTIVE: To describe the effects of stevia and D-tagatose intake on parameters associated to glucose, uric acid metabolism and on appetite-satiety, considering the available evidence. METHODS: Descriptive review. PubMed search was carried out to identify the totality of the published articles. The following terms and key words were used: "stevia rebaudiana", "tagatose", "D-tagatose", "blood glucose", "insulin", "metabolic processes", "uric acid", "hyperuricemia", "appetite" o "satiety". The analysis of the selected studies was discretionary. RESULTS: studies have shown beneficial effects of stevia and D-tagatose consumption on glycemic control, appetite and satiety in healthy subjects as well as subjects with impairment glucose metabolism. On the other hand, a significant number of studies evaluating estevia intake report null effects on these parameters. In relation to uric acid, only one study in subjects with chronic kidney disease reported an increase in plasmatic uric acid concentration after the intake of 500 mg/day of stevia. Several studies have evaluated the effect of D-tagatose intake on plasmatic uric acid, in healthy and diabetic subjects, reporting a transient and significant increase in serum uric acid levels, however, has not been able to demonstrate an associated hyperuricemic effect. It is important to highlight that the methodology of the studies reviewed is heterogeneous, especially in relation to sample size, dose administered, time and route of exposure to the sweetener. CONCLUSION: Stevia and D-tagatose intake has shown beneficial effects on glucose metabolism, appetite and satiety. The effects of the consumption of both sweeteners on uric acid require further study to demonstrate their clinic significance.

Protective effect of Cardiospermum halicacabum leaf extract on glycoprotein components on STZ-induced hyperglycemic rats

OBJECTIVE@#To investigate the protective role of Cardiospermum halicacabum (C. halicacabum) leaf extract on glycoprotein metabolism in streptozotocin (STZ)-induced diabetic rats.@*METHODS@#Diabetes was induced in male albino Wistar rats by intraperitonial administration of STZ. The C. halicacabum leaf extract (CHE) was administered orally to normal and STZ-diabetic rats for 45 days. The effects of C. halicacabum leaf extract (CHE) on plasma and tissue glycoproteins (hexose, hexosamine, fucose and sialic acid) were determined.@*RESULTS@#The levels of plasma and tissues glycoproteins containing hexose, hexosamine and fucose were significantly increased in STZ-induced diabetic rats. In addition, the level of sialic acid significantly increased in plasma and liver while decreased in kidney of STZ-induced diabetic rats. After administration of CHE to diabetic rats, the metabolic alteration of glycoprotein reverted towards normal levels.@*CONCLUSIONS@#The present study indicates that the CHE possesses a protective effect on abnormal glycoprotein metabolism in addition to its antihyperglycemic activity.

Screening of food-grade microorganisms for biotransformation of D-tagatose and cloning and expression of L-arabinose isomerase / 生物工程学报

L-Arabinose isomerase (L-AI) is an intracellular enzyme that catalyzes the reversible isomerization of D-galactose and D-tagatose. Given the widespread use of D-tagatose in the food industry, food-grade microorganisms and the derivation of L-AI for the production of D-tagatose is gaining increased attention. In the current study, food-grade strains from different foods that can convert D-galactose to D-tagatose were screened. According to physiological, biochemical, and 16S rDNA gene analyses, the selected strain was found to share 99% identity with Pediococcus pentosaceus, and was named as Pediococcus pentosaceus PC-5. The araA gene encoding L-AI from Pediococcus pentosaceus PC-5 was cloned and overexpressed in E. coli BL21. The yield of D-tagatose using D-galactose as the substrate catalyzed by the crude enzyme in the presence of Mn2+ was found to be 33% at 40 degrees C.

Crystal structures of D-psicose 3-epimerase from Clostridium cellulolyticum H10 and its complex with ketohexose sugars

D-psicose 3-epimerase (DPEase) is demonstrated to be useful in the bioproduction of D-psicose, a rare hexose sugar, from D-fructose, found plenty in nature. Clostridium cellulolyticum H10 has recently been identified as a DPEase that can epimerize D-fructose to yield D-psicose with a much higher conversion rate when compared with the conventionally used DTEase. In this study, the crystal structure of the C. cellulolyticum DPEase was determined. The enzyme assembles into a tetramer and each subunit shows a (β/α)(8) TIM barrel fold with a Mn(2+) metal ion in the active site. Additional crystal structures of the enzyme in complex with substrates/products (D-psicose, D-fructose, D-tagatose and D-sorbose) were also determined. From the complex structures of C. cellulolyticum DPEase with D-psicose and D-fructose, the enzyme has much more interactions with D-psicose than D-fructose by forming more hydrogen bonds between the substrate and the active site residues. Accordingly, based on these ketohexose-bound complex structures, a C3-O3 proton-exchange mechanism for the conversion between D-psicose and D-fructose is proposed here. These results provide a clear idea for the deprotonation/protonation roles of E150 and E244 in catalysis.

Caracterização dos genes que codificam a enzima dihidrolipomida desidrogenase (TcLip DH) e a proteína transportadora de hexoses (TcrHT1) em cepas do Trypanosoma Cruzi sensíveis e resistentes ao benzonidazol

A glicose e outras hexoses são importantes para o funcionamento das células eucariotas. Os transportadores de hexoses são proteínas transmembrana que levam o substrato para dentro da célula. Na glicólise, o açúcar captado é convertido em piruvato e este, por sua vez, é convertido a acetil-CoA para o ciclo do ácido cítrico. A conversão do piruvato a acetil-CoA conta com a participação da enzima lipoamida desidrogenase(LipDH), uma flavoenzima homodimérica da família das FAD-dissulfeto oxiredutase que é também importante para o mecanismo de oxiredução da célula. Murta et al. (2008, in press), utilizando a metodologia Differential Display (DD) selecionaram os genes que codificam o transportador de hexoses (TcrHT1) e a enzima lipoamida desidrogenase (TcLipDH) como genes mais expressos em uma cepa do T. cruzi com resistência induzida in vitro ao benzonidazol BZ e, que, portanto, seriam alvos em potencial para quimioterapia. Neste estudo, a fim de caracterizar os genes TcrHT1 e TcLipDH, foram analisados os níveis de mRNA; a organização genômica, a amplificação e a presença de polimorfismos; o nível de expressão ou atividade da proteína e a localização cromossômica em cepas do T. cruzi sensíveis e resistentes ao BZ.

Ensaios de Northern blot e PCR em Tempo Real confirmaram os resultados de DD e mostraram que ambos estão cerca de 2X mais expressos na cepa com resistência induzida in vitro ao BZ, 17LER, quando comparada a seu par sensível, 17WTS. Por Southern blot confirmamos que o gene TcLipDH possui duas cópias e o TcrHT1, um arranjo em “tandem” e não estão amplificados no genoma de nenhuma cepa resistente. Além disso, foi encontrado um polimorfismo para o gene TcrHT1 que não está relacionado ao fenótipo de resistência a drogas e sim com o zimodema ao qual as cepas analisadas pertencem. Os resultados de Western blot mostraram que a enzima TcLipDH está igualmente expressa em todas as cepas analisadas à exceção da cepa 17LER na qual a proteína está 2X menos expressa em comparação à 17WTS. Devido à dificuldade de obter anticorpos anti-TcrHT1, os ensaios de Western blotting foram substituídos pelo ensaio de atividade enzimática no qual constatamos que a eficiência de captação de glicose é 40% menor na cepa 17LER quando comparada à 17WTS. A localização cromossômica desses genes não está relacionada à resistência e é zimodema-dependente para o gene TcrHT1. Análises de bioinformática permitiram contextualizar evolutivamente ambos os genes e geraram informações interessantes sobre filogenia e anotação no genoma

Caracterização dos genes que codificam a enzima dihidrolipomida desidrogenase (TcLip DH) e a proteína transportadora de hexoses (TcrHT1) em cepas do Trypanosoma Cruzi sensíveis e resistentes ao benzonidazol / Characterization of genes encoding the enzyme dihidrolipomida dehydrogenase (TcLip DH) and hexose transporter protein (TcrHT1) of Trypanosoma cruzi in strains sensitive and resistant to benznidazole

A glicose e outras hexoses são importantes para o funcionamento das células eucariotas. Os transportadores de hexoses são proteínas transmembrana que levam o substrato para dentro da célula. Na glicólise, o açúcar captado é convertido em piruvato e este, por sua vez, é convertido a acetil-CoA para o ciclo do ácido cítrico. A conversão do piruvato a acetil-CoA conta com a participação da enzima lipoamida desidrogenase(LipDH), uma flavoenzima homodimérica da família das FAD-dissulfeto oxiredutase que é também importante para o mecanismo de oxiredução da célula. Murta et al. (2008, in press), utilizando a metodologia Differential Display (DD) selecionaram os genes que codificam o transportador de hexoses (TcrHT1) e a enzima lipoamida desidrogenase (TcLipDH) como genes mais expressos em uma cepa do T. cruzi com resistência induzida in vitro ao benzonidazol BZ e, que, portanto, seriam alvos em potencial para quimioterapia. Neste estudo, a fim de caracterizar os genes TcrHT1 e TcLipDH, foram analisados os níveis de mRNA; a organização genômica, a amplificação e a presença de polimorfismos; o nível de expressão ou atividade da proteína e a localização cromossômica em cepas do T. cruzi sensíveis e resistentes ao BZ.

Ensaios de Northern blot e PCR em Tempo Real confirmaram os resultados de DD e mostraram que ambos estão cerca de 2X mais expressos na cepa com resistência induzida in vitro ao BZ, 17LER, quando comparada a seu par sensível, 17WTS. Por Southern blot confirmamos que o gene TcLipDH possui duas cópias e o TcrHT1, um arranjo em “tandem” e não estão amplificados no genoma de nenhuma cepa resistente. Além disso, foi encontrado um polimorfismo para o gene TcrHT1 que não está relacionado ao fenótipo de resistência a drogas e sim com o zimodema ao qual as cepas analisadas pertencem. Os resultados de Western blot mostraram que a enzima TcLipDH está igualmente expressa em todas as cepas analisadas à exceção da cepa 17LER na qual a proteína está 2X menos expressa em comparação à 17WTS. Devido à dificuldade de obter anticorpos anti-TcrHT1, os ensaios de Western blotting foram substituídos pelo ensaio de atividade enzimática no qual constatamos que a eficiência de captação de glicose é 40% menor na cepa 17LER quando comparada à 17WTS. A localização cromossômica desses genes não está relacionada à resistência e é zimodema-dependente para o gene TcrHT1. Análises de bioinformática permitiram contextualizar evolutivamente ambos os genes e geraram informações interessantes sobre filogenia e anotação no genoma

Effect of ciprofloxacin and chloramphenicol on humoral immune response elicited by bovine albumin encapsulated in niosomes / 药学学报

The aim is to evaluate the effect of ciprofloxacin and chloramphenicol on anti-BSA antibody production triggered by bovine albumin encapsulated in non-ionic surfactant vesicle, niosomes. Reverse phase evaporation method was adopted to entrap the antigen in colloidal carrier composed of Span 80 and Span 85 followed by simultaneous characterization for particle size, entrapment efficiency and in vitro release. The protein content was determined by Bradford method using UV Visible Spectrophotometer at 595 nm. Humoral immune response was measured in terms of systemic IgG antibody titre by ELISA method. Experimental data indicated that 7 : 3 molar ratio of Span 80 and cholesterol based niosomal formulation possessed maximum (39.8 +/- 2.9)% of soluble protein. Ciprofloxacin markedly (P < 0.05) decreased the antibody titre. In contrast, chloramphenicol did not reduce the antibody titre significantly in comparison to control group (P > 0.05). It is necessary to explore the effect of a vaccine antigen when a candidate is medicated with a therapeutic agent, which might help in programming a new drug management and vaccination programme.

9-nitrocamptothecin nanostructured lipid carrier system: in vitro releasing characteristics, uptake by cells, and tissue distribution in vivo / 药学学报

<p><b>AIM</b>To study the release and cell uptake characteristics of 9-nitrocamptothecin (9-NC) nanostructured lipid carrier system (NLC) in vitro and its tissue distribution characteristics in vivo.</p><p><b>METHODS</b>Mouse peritoneal macrophages were used to investigate the uptake of nanoparticles by cells in vitro. The tissue distribution of 9-nitrocamptothecin solution and stealth nanostructured lipid carrier system (S-NLC) was determined after intravenous administration to mice at a single dose of 1.5 mg kg(-1). The release and crystalloid characteristics were also investigated.</p><p><b>RESULTS</b>X-ray diffraction spectrum showed that 9-NC probably was amorphous in S-NLC. The liquid lipid did not change the characteristics of the solid matrix in nanoparticles. The in vitro release and cell uptake characteristics of stealth and non-stealth 9-NC-NLC were investigated, separately. The results showed that the stealth 9-NC-NLC had sustained-release characteristics and could resist the absorption effect of the additional plasmas to a certain extent. In addition, the cell uptake percentage of stealth 9-NC-NLC was much lower than that of the non-stealth ones. The tissues distribution results showed that 9-NC in the S-NLC was mainly found in the lung, liver, pancreas and ovary/uterus, while the quantity of 9-NC was much lower in heart and kidney. The AUQ(0-t), of S-NLC in blood, ovary/uterus, pancreas, liver and lung were higher than that of 9-nitrocamptothecin solution. The weight-average drug targeting efficiency (Te*) of S-NLC in liver and lung were significantly higher than that of 9-nitrocamptothecin solution. The mean residence times (MRT) of S-NLC was 44 h, while that of 9-nitrocamptothecin solution was 8 h. Therefore, S-NLC showed obvious targeting effects on liver and lung.</p><p><b>CONCLUSION</b>S-NLC with PEG flexible chains has sustained-release characteristics and can prolong its circulation in blood and have good targeting efficiency on liver and lung.</p>

Importância da dosagem da amilase e da glicose na rotina de investigação da causa dos derrames pleurais / Importance of glucose and amylase concentration in the routine investigation of a pleural effusion

A dosagem da glicose e amilase vem sendo realizada na rotina de investigação da causa de derrames pleurais. Nosso objetivo é verificar a contribuição destas para o diagnóstico final. Método: estudamos 192 toracocenteses subseqüentes com derrame pleural, entre agosto 1995 e dezembro de 2000. Foram excluídos aqueles nos quais um diagnóstico de certeza não foi possível e pacientes já incluídos anteriormente. As propriedades do teste diagnóstico foram calculadas após identificar o valor discriminatório de maior acurácia pela curva ROC. Resultados: houve predomínio do sexo masculino e a média de idade foi de 50 anos (DP de 19,8). O rendimento de ambas as dosagens para o diagnóstico diferencial entre transudato e exsudato foi ruim. A glicose, com valor discriminatório de < 90mg/dL, mostrou uma sensibilidadede 94% e especificidade de 65% para o diagnóstico da tuberculose. A amilase (valor < 52U/L), para o diagnóstico diferencial entre neoplasia e um grupo composto por tuberculose, parapneumônico e transudato mostrou uma sensibilidade de 56% e especificidade de 58%. Conclusões:a dosagem da glicose e da amilase no líquido pleural não são úteis, isoladamente, para se estabelecer a causa do derrame pleural em nosso meio e não devem ser solicitadas de rotina no início da investigação. Contudo, em casos especiais podem ser de grande ajuda.

Lipase-catalyzed enantioselective ammonolysis of racemic phenylglycine methyl ester in organic solvent / 生物工程学报

A novel reaction-enzymatic ammonolysis discovered in the mid of 1990s has been demonstrated to be a very promising alternative in the preparation of optically pure compounds. The effects of organic solvent, initial water activity, temperature and additives on lipase Novozym435-catalyzed enantioselective ammonolysis of racemic phenylglycine methyl ester were investigated systematically in this paper. Enzymatic reaction of ammonolysis showed higher activity and enantioselectivity than the corresponding reaction of hydrolysis and alcoholysis.

Effect of different nutritional routes on the intestinal mucus barrier in scalded rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To observe the effect of different nutritional routes of giving nutrition on the intestinal mucus barrier in severely scalded rats.</p><p><b>METHODS</b>Wistar rats inflicted with 30% TBSA III degree scalding on the back were employed as the model and were randomly divided into 3 groups, i.e. control (C), parenteral nutrition (PN) and enteral nutrition (EN) groups. The rats in PN and EN groups were supplied with equal amount of nitrogen and calories and with equal volume of nutrition solution. The dynamic changes in the thickness of intestinal mucus layer and the contents of protein, hexose and acetylneuraminate in the mucus were examined.</p><p><b>RESULTS</b>When compared with those in C group, the intestinal mucus layer became thinner and the contents of protein, hexose and acetylneuraminate in the mucus in both PN and EN groups decreased evidently after scalding. When compared between two nutritional groups, the thickness of intestinal mucus layer and the contents of the hexose and acetylneuraminate in the mucus in EN were much thicker and higher than those in PN group, while the mucus protein content exhibited no obvious difference between PN and EN groups.</p><p><b>CONCLUSION</b>It was suggested that intestinal goblet cell synthesized and secreted less mucus after scalding in rats resulting in thinning of intestinal mucus layer and the change in mucus components. When compared with those in PN group, less injury to the intestinal goblet cells occurred and the intestinal mucus synthesis was less affected in EN group, and the components of intestinal mucus were maintained stable.</p>

Interconversion of free sugars in relation to activities of enzymes catalyzing synthesis and cleavage of sucrose in growing stem tissues of sorghum.

Free sugar interconversion and activities of soluble acidic (pH 4.8) and neutral (pH 7.5) invertases, sucrose synthase (synthesis) and sucrose phosphate synthase were investigated in the growing nodes and internodes of sorghum (Sorghum vulgare). The results were substantiated with incorporation of 14C from supplied sucrose and hexoses into endogenous sugars of these stem tissues. With the advancement in plant growth, the content of total free sugars in apical nodes and internodes increased till 70 DAS (flowering stage) followed by a decline. In the corresponding basal tissues, the sugar build-up continued even beyond this stage of plant growth. Compared with basal stem tissues, the apical ones contained high activities of soluble invertases and a low proportion amongst free sugars of sucrose. The activities of sucrose-hydrolyzing enzymes were higher as compared with those of sucrose-synthesizing ones in both nodes and internodes and with the growth of plant, the activity of neutral invertase increased in these tissues. More 14C from supplied sucrose and hexoses appeared in extracted sugars from cut discs of apical nodes and internodes in comparison with their basal counterparts. 14C from supplied sucrose appeared in glucose, fructose and from supplied hexoses appeared in sucrose. The results suggest that in apical nodes and internodes, where a rapid cell division and cell expansion occur, sucrose is obligatorily inverted to meet the increased requirement of hexoses and there is a compartmentalized synthesis and cleavage of sucrose in the nodes and internodes of growing sorghum plant.

Evaluation of glycoproteins as prognosticators in head and neck malignancy.

Although several serum glycoprotein assays have been conducted for identifying tumor markers and prognosticators of malignancies, presently assessment of effectiveness of treatment of these malignancies remains subjective and good and effective tumor markers and prognosticators of head and neck malignancies are yet to be identified. In our study, serum samples from forty patients with head and neck cancers who were divided into four groups of ten patients each on the basis of their clinical staging and serum samples from ten healthy individuals comprising the control group was taken and subjected to biochemical analysis of serum protein bound hexose, serum fucose, serum sialic acid levels before starting treatment of the cancers and after completion of the cancer treatment and compared with the levels of these serum glycoproteins amongst the control group. All the head and neck cancer patients showed elevated levels of the serum glycoproteins as compared to the control group. It was further noted that the increased levels of the serum glycoproteins correlated well with the clinical staging of the malignancies. Post-treatment levels of all the serum glycoproteins were decreased significantly but, only the serum sialic acid level in 6 out of 10 patients with stage-I malignancy returned to the base line levels as seen in the control group. Serum sialic acid levels showed very close correlation with tumor staging and maybe considered as a good tumor marker and prognosticator for detection of cancer and evaluation of effectiveness of treatment of head and neck malignancies.

Niveles séricos de mucoproteínas y de proteínas combinadas con hexosas o con ácido siálico en escolares enfermos residentes en la ciudad de Mérida (Venezuela) / Mucoproteins serum levels and combination proteins with hexoses or with sialic acid the sick student resinding at the Mérida city (Venezuela)

En el presente trabajo se cuantificó el contenido sérico de las mucoproteínas y de las proteínas combinadas con hexosas (PBH) o con ácido siálico (PAS) en 440 escolares portadores de diversas patologías (GRUPO DE CASOS) y se comparó con los hallazgos obtenidos en 160 escolares sanos con características similares a los casos (GRUPO TESTIGO). Los valores de mucoproteínas, PBH y PAS en los escolares sanos fueron 15ñ9, 112ñ20 y 66ñ12 mg/dL, respectivamente, los cuales se utilizaron para comparar con los casos. En los escolares enfermos no tratados los niveles de estas seroglicoproteínas difieren significativamente (p<0.05), dependiendo de la patología en estudio, al comparar con los valores normales y de los escolares tratados. En las piodermitis y en las parasitosis se encuentran valores de PBH inferiores al rango normal, igual fenómeno se detectó con las mucoproteínas en las hepatitis virales e infecciones agudas. Cuando los tratamientos son adecuados, los valores alterados de las glicoproteínas rápidamente retornan a la normalidad. Se concluye que la determinación de estas seroglicoproteínas puede ser un auxiliar útil para evaluar la respuesta de los pacientes al tratamiento (s) y en casos de diagnóstico difícil, tal como sucede en los escolares ictéricos

Administration of the plasticizer di (2-ethylhexyl) phthalate alters glycoconjugate profile.

This study was undertaken to evaluate the level of glycoproteins and sialic acid in rats fed di (2-ethylhexyl)-phthalate (DEHP) in the diet for 24 weeks. Protein-bound hexose, hexosamine and sialic acid were increased in plasma and liver of rats treated with DEHP, whereas the erythrocyte membrane showed a reduction following DEHP administration. Evaluation of glycoproteins is a useful indicator of the carcinogenic process. It is suggested that profound alterations in membrane components observed in the present study may be related to the carcinogenic potential of DEHP.

The separation and identification of picomole amounts of intermediates of glucose metabolism by high performance liquid chromatography on pellicular resins

A column (CarboPac PA1, Dionex) containing an anion-exchange pellicular resin was used for the separation of phosphoryl-hexoses derived from labeled glucose microinjected into individual frog oocytes or from cultures of Escherichia coli. Intermediates were identified by: a) comparison of retention times with those of authentic commercial compounds; b) the use of internal labeled standards; c) incubation of samples with specific enzymes and noting the disappearance of one radioactive peak and appearance of another at a new retention time

Impact of surface modifications of Acanthocheilonema viteae microfilariae on cell adhesion.

Exposure of A. viteae microfilariae to various lectins reduced their capacity to react with the peritoneal exudate cells of the host, Mastomys natalensis. Sugars corresponding to these lectins with the exception of N-acetyl glucosamine, did not affect the adhesion per se. They however, protected the parasite against the adverse effect of lectins. Neuraminidase and chitinase also suppressed adhesion capacity of the microfilariae. Except sodium dodecylsulphate which enhanced cell attachment, other surfactants inhibited this reaction considerably. The results indicate that antibody dependent adhesion of the microfilariae with the macrophages involves surface moieties of the parasite, where N-acetylglucosamine acts as the principal sugar residue. Participation of -SH groups also is inferred from the observations that p-chloromercuribenzoate and dithiobis-(2-nitrobenzoic acid) inhibited cell attachment and dithiothreitol provided protection against these agents.

Improved spectrophotometric determination of disaccharides, hexoses and pentoses using aniline and its alkyl derivatives

Aniline and its alkyl derivatives in acetic acid media react with hexoses and pentoses to form colored products with characteristic absorption spectra. The spectral for individual hexoses, pentoses and their dehydration products and tend to vary with a given aniline derivative. The chromogen formed showed absorption at wavelength 530, 470 and 330mm. The method was improved and used to determine quantitatively glucoses, fructose, maltose, sucrose and ribose and the result obtained was found to obey Beer's law for a concentration range of [0.4-30mg mL-1] for glucose [0.2-2.2 mg.mL-1] for invert sugar [sucrose], [1-3,4mg.mL-1] for maltose under the specific condition that chosen for determination of each sugar