Expression of enzymes involved in the urea cycle and muscle and mammary gland development of Holstein × Gyr heifers in a rotational grazing system supplemented with increasing protein levels.

Studies evaluating the crude protein (CP) supplementation strategies across the year for grazing cattle and its association with the enzymes involved in the urea cycle and muscle and mammary gland developments are scarce. Thus, we aimed to evaluate the effect of supplementation with different levels of CP on the expression of genes involved in the urea cycle and muscle and mammary gland development of Holstein × Gyr crossbreed heifers grazing intensively managed Brachiaria decumbens throughout the year. Thirty-eight heifers with average initial BW of 172.5 ± 11.15 kg (mean ± SE) and 8.2 ± 0.54 mo of age were randomly assigned to 1 of 4 treatments: 3 protein supplements (SUP) fed at 5g/kg of body weight, plus a control group (CON, non-supplemented animals). The supplement CP levels evaluated were: 12, 24, and 36%. The study was divided into 4 seasons: rainy, dry, rainy-dry transition (RDT), and dry-rainy transition (DRT). On the penultimate day of each season, ultrasound images of the carcass and mammary gland were taken. Five animals from each treatment were randomly chosen on the last day of each season, and liver and muscle tissue biopsies were performed. The target genes were the mammalian target of rapamycin (mTOR) and adenosine monophosphate-activated protein kinase (AMPK) in the muscle samples. Carbamoyl phosphate synthetase (CPS), ornithine transcarbamylase (OTC), argininosuccinate synthetase (ASS), arginosuccinate lyase (ASL), and arginase (ARG) were evaluated in the liver samples. Data were analyzed using PROC GLIMMIX of the SAS with repeated measures. We observed a greater rib eye area (cm2) and fat thickness (mm) in SUP animals than in non-supplemented animals. However, we did not observe differences among SUP levels for both variables. No effects of supplementation were detected on mammary gland development. Nevertheless, seasonal effects were observed, where the RDT and dry season had the most and least accumulated fat in the mammary gland. In muscle, we observed greater expression of AMPK in non-supplemented animals than SUP animals. On the other hand, no differences were observed in gene expression between SUP and non-supplemented animals and among SUP animals for mTOR. Season affected both AMPK and mTOR; heifers had a greater AMPK gene expression on rainy than RDT. For mTOR, we observed greater gene expression in RDT and DRT than in rainy. No differences were observed among RDT, dry, and DRT, and between dry and rainy seasons for mTOR. We observed greater CPS, ASL, and ARG gene expression in SUP animals than in non-supplemented animals. Among SUP animals, supplement CP linearly affected CPS. In conclusion, the supplementation strategy did not affect mammary gland development and mTOR expression in muscle tissue. However, we observed a seasonal effect on mammary gland development and AMPK and mTOR expression. The CP supplementation increased the rib eye area and fat thickness, directly affecting AMPK expression in the muscle. Moreover, the CP supplementation increased urea cycle enzyme expression, indicating greater urea production in the liver.

Desenvolvimento ponderal e parâmetros hematológicos e bioquímicos de cordeiros Pantaneiros submetidos a diferentes manejos de amamentação / [Ponderal development and hematological and biochemical parameters of Pantaneiro lambs subjected to different suckling regimens]

Este estudo teve por objetivo avaliar o desenvolvimento ponderal e a dinâmica dos parâmetros hematológicos e bioquímicos de cordeiros Pantaneiros submetidos a diferentes manejos de amamentação dos 15 aos 43 dias. Foram separados 30 cordeiros em três diferentes grupos (n=10). Os grupos foram caracterizados conforme o tempo de permanência das ovelhas com suas crias em diferentes sistemas de amamentação: MAM24 - ovelhas e cordeiros 24 horas em conjunto; MAM12 - ovelhas e cordeiros 12 horas em conjunto durante a noite; MAM2x30 - ovelhas e cordeiros 30 minutos de manhã e 30 minutos à tarde em conjunto. As coletas de amostras sanguíneas e as pesagens ocorriam a cada sete dias. Houve aumento significativo no peso com o avanço da idade dos cordeiros nos três manejos, mas os tratamentos não diferiram entre si para o ganho de peso. Houve diferenças entre os três tratamentos para a variável hematológica CHGM e para as variáveis bioquímicas AST, glicose, ureia e proteína total. As variáveis bioquímicas foram influenciadas pela faixa etária dos animais. Os diferentes manejos de amamentação não influenciaram o desenvolvimento ponderal dos cordeiros. Não ocorreram alterações patológicas. Alguns parâmetros hematológicos e bioquímicos podem ser influenciados pelo desenvolvimento etário dos cordeiros.(AU)

This study aimed to evaluate the weight development and the dynamics of hematological and biochemical parameters of Pantaneiro lambs submitted to different breastfeeding management from 15 to 43 days. First, 30 lambs were separated into three different groups (n = 10). The groups were characterized according to the length of stay of ewes with their young in different breastfeeding systems: MAM24 - ewes and lambs 24 hours together. MAM12- Sheep and lambs 12 hours together at night. MAM2x30 - sheep and lambs 30 minutes in the morning and 30 minutes in the afternoon together. Blood samples were collected and weighed every seven days. Significant increase in weight was observed with the age of the lambs in the three managements, but the treatments did not differ for weight gain. Differences were identified between the three treatments for the hematological variable CHGM and for the biochemical variables AST, glucose, urea and total protein. Correlating the age of the lambs with the biochemical variables, there was variation influenced by the age of the animals. The different management of breastfeeding did not influence the weight development of the lambs. Hematological and biochemical variations did not represent pathological changes. Some hematological and biochemical parameters may be influenced by the age development of lambs.(AU)

Aluminum fractionation in acidic soils and river sediments in the Upper Mero basin (Galicia, NW Spain).

This study aims to determine aluminum fractions in the fine earth of acidic soils under different land uses (forest, pasture and cultivation) and in the river bed sediments of the headwater of the Mero River in order to identify and quantify Al-bearing phases to assess Al mobility and potential bioavailability (environmental availability) in the monitoring area. Sequential extraction is used to evaluate the Al partitioning into six fractions operationally defined: soluble/exchangeable/specifically adsorbed, bound to manganese oxides, associated with amorphous compounds, aluminum bound to oxidizable organic matter, associated with crystalline iron oxides, and residual fraction (aluminum within the crystal lattices of minerals). The mean concentration of total aluminum (24.01 g kg-1) was similar for the three considered uses. The mean percentage of the aluminum fractions, both in soils and sediments, showed the following order: residual fraction â‰« amorphous compounds ≈ crystalline iron oxides > water-soluble/exchangeable/specifically adsorbed > bound to oxidizable organic matter ≈ Mn oxides. However, in the soils, the amorphous compounds and water-soluble/exchangeable/specifically adsorbed fraction showed considerable differences between some types of uses, the percentage of aluminum linked to amorphous compounds being higher in forest soils (16% of total Al) compared to other uses (mean about 8% of total Al). The highest values of water-soluble/exchangeable/specifically adsorbed Al were also found in forest soils (mean 8.6% of the total Al versus about 4% of pasture and cultivation), which is consistent with the lower pH and higher organic matter content in forest soils. Nevertheless, the potentially bioavailable fraction (sum of the first three fractions) is low, suggesting very low geoavailability of this element in both soils and sediments; hence, the possibility to affect the crops and water quality is minimal.

Therapeutic properties of VO(dmpp)2 as assessed by in vitro and in vivo studies in type 2 diabetic GK rats.

The bis(1,2-dimethyl-3-hydroxy-4-pyridinonato)oxidovanadium(IV), VO(dmpp)2, has shown anti-diabetic effects by in vitro studies in Wistar (W) rat adipocytes and in vivo in obese Zucker rats. The aim of this work is to confirm the therapeutic properties of VO(dmpp)2 in non-obese type 2 diabetic Goto-Kakizaki (GK) rats. An in vivo study was carried out, treating W and GK rats during 21 days with a daily dose of VO(dmpp)2 (44 µmol/kg). It was shown that VO(dmpp)2 doesn't affect the normal increase of body weight of both W and GK rats, after 8 days of treatment ameliorates glycemia in GK rats (8.4 ± 0.3 vs 10.1 ± 0.2 mM in GK control, P<0.001) but doesn't interfere with glucose levels in W rats and, after 21 days of treatment, improves the glucose intolerant profile of GK rats (13.1 ± 0.5 vs 20.6 ± 0.7 mM/min in GK control, P<0.001), despite no increase of plasma insulin levels during glucose tolerance test. Additionally, it was demonstrated that VO(dmpp)2 significantly enhances [3-(3)H]-glucose uptake by W and GK rat adipocytes (non-toxic concentration of 100 µM: respectively 193 ± 20 and 254 ± 21%, P<0.001, relative to the basal value) showing an efficacy similar to insulin 1.72 nM and better than the same concentration of BMOV (P<0.01). Western blotting revealed that in W and GK rats VO(dmpp)2 significantly promotes IRS2 (P<0.05) and p-AKT expression (P<0.001 and P<0.05, respectively, relative to the respective controls) and in GK animals reduces the increase of PTP1ß expression (P<0.001, relative to GK control).

Inhibitory effects of caspase inhibitors on the activity of matrix metalloproteinase-2.

Matrix metalloproteinase (MMP)-2, a zinc-dependent endopeptidase, plays a detrimental role in several diseases including ischemia and reperfusion (I/R) injury of the heart. Caspases are a group of cysteine-dependent, aspartate-directed proteases which regulate cellular apoptosis. Interestingly, protective effects of caspase inhibitors independent of apoptosis have been shown in I/R injury of the heart. The cardioprotective actions of both these classes of protease inhibitors led us to hypothesize that caspase inhibitors may also reduce MMP-2 activity. Five known caspase inhibitors (Z-IE(OMe)TD(OMe)-fmk, Ac-DEVD-CHO, Ac-LEHD-cmk, Z-VAD-fmk and Ac-YVAD-cmk) were tested for their possible inhibitory effects on MMP-2 activity in comparison to the MMP inhibitors ONO-4817 and ARP-100 (which themselves were unable to inhibit caspase-3 activity). MMP-2 activity was assessed by an in vitro troponin I (TnI) proteolysis assay and a quantitative kinetic fluorescence assay using a fluorogenic peptide substrate (OmniMMP). TnI proteolysis was also measured by western blot in neonatal cardiomyocytes subjected to hypoxia-reoxygenation injury. Using human recombinant MMP-2 and TnI as its substrate, the caspase inhibitors, in comparison with ONO-4817, significantly inhibited MMP-2-mediated TnI degradation in a concentration-dependent manner. The kinetic assay using OmniMMP revealed that these caspase inhibitors blocked MMP-2 activity in a concentration-dependent manner with similar IC50 values. TnI degradation in neonatal cardiomyocytes was enhanced following hypoxia-reoxygenation and this was blocked by ARP-100 and Ac-LEHD-cmk. Inhibition of MMP-2 activity is an additional pharmacological action which contributes to the protective effects of some caspase inhibitors.

Prevalence of human papillomavirus (HPV) type 16 variants and rare HPV types in the central Amazon region.

Infection by human papillomavirus (HPV) is one of the primary causes of mortality by cancer in northern Brazil. Sexually active women from Manaus, Amazonas, without cytological alterations and women with pre-malignant and malignant cytological alterations were examined for HPV virus, identified via PCR and sequencing. The target region for this study was part of the L1 capsid gene of HPV. Twenty-three samples that were PCR-positive were sequenced. Analysis of 336 bp demonstrated a high incidence of high-risk HPV types in the population of Manaus, identified as HPVs 16, 33, 58, 66, 68. HPV type 16 was the most prevalent, presenting two variants similar to the Asian-American (AA) and East-Asian type (As) variants. A rare HPV type 13 related to "Heck's disease" was also detected. This preliminary provides important information about the HPV circulating in Amazonas State.

Tricarboxylic acid cycle inhibition by Li+ in the human neuroblastoma SH-SY5Y cell line: a 13C NMR isotopomer analysis.

Li+ effects on glucose metabolism and on the competitive metabolism of glucose and lactate were investigated in the human neuroblastoma SH-SY5Y cell line using 13C NMR spectroscopy. The metabolic model proposed for glucose and lactate metabolism in these cells, based on tcaCALC best fitting solutions, for both control and Li+ conditions, was consistent with: (i) a single pyruvate pool; (ii) anaplerotic flux from endogenous unlabelled substrates; (iii) no cycling between pyruvate and oxaloacetate. Li+ was shown to induce a 38 and 53% decrease, for 1 and 15 mM Li+, respectively, in the rate of glucose conversion into pyruvate, when [U-13C]glucose was present, while no effects on lactate production were observed. Pyruvate oxidation by the tricarboxylic acid cycle and citrate synthase flux were shown to be significantly reduced by 64 and 84% in the presence of 1 and 15 mM Li+, respectively, suggesting a direct inhibitory effect of Li+ on tricarboxylic acid cycle flux. This work also showed that when both glucose and lactate are present as energetic substrates, SH-SY5Y cells preferentially consumed exogenous lactate over glucose, as 62% of the acetyl-CoA was derived from [3-13C]lactate while only 26% was derived from [U-13C]glucose. Li+ did not significantly affect the relative utilisation of these two substrates by the cells or the residual contribution of unlabelled endogenous sources for the acetyl-CoA pool.

Intracellular lithium and cyclic AMP levels are mutually regulated in neuronal cells.

In this work, we studied the effect of intracellular 3',5'-cyclic adenosine monophosphate (cAMP) on Li+ transport in SH-SY5Y cells. The cells were stimulated with forskolin, an adenylate cyclase activator, or with the cAMP analogue, dibutyryl-cAMP. It was observed that under forskolin stimulation both the Li+ influx rate constant and the Li+ accumulation in these cells were increased. Dibutyryl-cAMP also increased Li+ uptake and identical results were obtained with cortical and hippocampal neurons. The inhibitor of the Na+/Ca2+ exchanger, KB-R7943, reduced the influx of Li+ under resting conditions, and completely inhibited the effect of forskolin on the accumulation of the cation. Intracellular Ca2+ chelation, or inhibition of N-type voltage-sensitive Ca2+ channels, or inhibition of cAMP-dependent protein kinase (PKA) also abolished the effect of forskolin on Li+ uptake. The involvement of Ca2+ on forskolin-induced Li+ uptake was confirmed by intracellular free Ca2+ measurements using fluorescence spectroscopy. Exposure of SH-SY5Y cells to 1 mm Li+ for 24 h increased basal cAMP levels, but preincubation with Li+, at the same concentration, decreased cAMP production in response to forskolin. To summarize, these results demonstrate that intracellular cAMP levels regulate the uptake of Li+ in a Ca(2+)-dependent manner, and indicate that Li+ plays an important role in the homeostasis of this second messenger in neuronal cells.

[Drug therapy follow-up in patients admitted to a Surgery Department]. / Seguimiento del tratamiento farmacológico en pacientes ingresados en un Servicio de Cirugía.

INTRODUCTION: Patients admitted to surgery departments receive multiple drugs before, during and after surgical procedures. Anti-infectious therapy, anesthetics, anti-embolic agents, and analgesics stand out amongst others. Our objective was to implement pharmacotherapeutic follow-up as a means to detect, prevent, and solve medication-related problems (MRPs) in inpatients, and to establish consensus strategies to solve avoidable MRPs. MATERIAL AND METHODS: An observational prospective study of 22 patients hospitalized in a Surgery Department, Hospital Infanta Margarita, Cabra (Córdoba) was conducted. Dader methodology was adapted for drug therapy follow-up in the hospital setting. RESULTS: In all, 108 MRPs were detected; 22.04% were associated with medication needs (MRP1:13.6% and MRP2: 8.5%), 40.68% with ineffectiveness (MRP3: 22.0% and MRP4: 18.6%), and 37.28% with lack of safety (MRP5: 10.2% and MRP6: 27.1%). Out of 108 MRPs found, 64 (59.3%) were avoidable; 97 pharmaceutical interventions were carried out (89.8% of cases), acting in 63 (58%) MRPs detected in cooperation with physicians, while 46 MRPs were solved (42%). We found 1 MRP in each 2.6 patients -- admission days, and 1 MRP per 4.5 patients -- admission days occurred after pharmaceutical intervention during the study period. CONCLUSIONS: The use of pharmacotherapeutic follow-up in patients admitted to this department has improved the quality of health care.

Effects of Li+ transport and intracellular binding on Li+/Mg2+ competition in bovine chromaffin cells.

Li(+) transport, intracellular immobilisation and Li(+)/Mg(2+) competition were studied in Li(+)-loaded bovine chromaffin cells. Li(+) influx rate constants, k(i), obtained by atomic absorption (AA) spectrophotometry, in control (without and with ouabain) and depolarising (without and with nitrendipine) conditions, showed that L-type voltage-sensitive Ca(2+) channels have an important role in Li(+) uptake under depolarising conditions. The Li(+) influx apparent rate constant, k(iapp), determined under control conditions by (7)Li NMR spectroscopy with the cells immobilised and perfused, was much lower than the AA-determined value for the cells in suspension. Loading of cell suspensions with 15 mmol l(-1) LiCl led, within 90 min, to a AA-measured total intracellular Li(+) concentration, [Li(+)](iT)=11.39+/-0.56 mmol (l cells)(-1), very close to the steady state value. The intracellular Li(+) T(1)/T(2) ratio of (7)Li NMR relaxation times of the Li(+)-loaded cells reflected a high degree of Li(+) immobilisation in bovine chromaffin cells, similar to neuroblastoma, but larger than for lymphoblastoma and erythrocyte cells. A 52% increase in the intracellular free Mg(2+) concentration, Delta[Mg(2+)](f)=0.27+/-0.05 mmol (l cells)(-1) was measured for chromaffin cells loaded with the Mg(2+)-specific fluorescent probe furaptra, after 90-min loading with 15 mmol l(-1) LiCl, using fluorescence spectroscopy, indicating significant displacement of Mg(2+) by Li(+) from its intracellular binding sites. Comparison with other cell types showed that the extent of intracellular Li(+)/Mg(2+) competition at the same Li(+) loading level depends on intracellular Li(+) transport and immobilisation in a cell-specific manner, being maximal for neuroblastoma cells.

Videolaparoscopic approach of the splenic cyst: a case report.

The authors report a case of an asymptomatic 30-year-old female patient with an extensive cystic lesion continuous with the splenic parenchyma. A review of the literature and use of a videolaparoscopic approach to the treatment of these lesions is presented.

Non-traumatic acute abdomen: videolaparoscopic approach.

BACKGROUND AND OBJECTIVE: Although videolaparoscopy has been considered a safe method for many elective procedures, its use in traumatic and non-traumatic acute abdomen needs to be evaluated. The aim of this article is to evaluate the role of videolaparoscopy in non-traumatic acute abdomen as a method of diagnosis and treatment. METHODS: Between January 1992 and December 1996, 462 patients' charts were reviewed, retrospectively. Patients were admitted to the emergency room of São Rafael Hospital with symptoms of non-traumatic acute abdomen. Routine investigation of abdominal pain was performed in all patients, followed by videolaparoscopy. The laparoscopic procedures were done with four main purposes: diagnosis (ie, enteritis); diagnosis and treatment (ie, appendicitis); treatment only, when the diagnosis was known (ie, acute cholecystitis); and in cases where the conversion to conventional laparotomy was necessary, indicating the best incision. RESULTS: The vast majority of patients had inflammatory causes of acute abdomen (82.03%); others causes were hemoperitoneum (11.03%), bowel obstruction (3.25%), perforation of a hollow viscera (1.74%), vascular occlusion (1.3%), and negative laparoscopy (0.65%). CONCLUSIONS: This study shows that laparotomy was necessary in only 7.14% of the patients. The videolaparoscopic approach was used for diagnosis (99.35%) and treatment (92.86%) of patients with acute abdomen.

Competition between Li+ and Mg2+ in neuroblastoma SH-SY5Y cells: a fluorescence and 31P NMR study.

Because Mg2+ and Li+ ions have similar chemical properties, we have hypothesized that Li+/Mg2+ competition for Mg2+ binding sites is the molecular basis for the therapeutic action of lithium in manic-depressive illness. By fluorescence spectroscopy with furaptra-loaded cells, the free intracellular Mg2+ concentration within the intact neuroblastoma cells was found to increase from 0. 39 +/- 0.04 mM to 0.60 +/- 0.04 mM during a 40-min Li+ incubation in which the total intracellular Li+ concentration increased from 0 to 5.5 mM. Our fluorescence microscopy observations of Li+-free and Li+-loaded cells also indicate an increase in free Mg2+ concentration upon Li+ incubation. By 31P NMR, the free intracellular Mg2+ concentrations for Li+-free cells was 0.35 +/- 0. 03 mM and 0.80 +/- 0.04 mM for Li+-loaded cells (final total intracellular Li+ concentration of 16 mM). If a Li+/Mg2+ competition mechanism is present in neuroblastoma cells, an increase in the total intracellular Li+ concentration is expected to result in an increase in the free intracellular Mg2+ concentration, because Li+ displaces Mg2+ from its binding sites within the nerve cell. The fluorescence spectroscopy, fluorescence microscopy, and 31P NMR spectroscopy studies presented here have shown this to be the case.

Videolaparocholecystectomy: casuistry of 1000 cases.

Despite the ongoing evolution in the medical treatment of biliary pathology, the standard of treatment for gallstones remains cholecystectomy. There are no alternative treatments that have shown the same efficacy as surgery. Current alternative treatments have shown high recurrence and failure rates. Cholecystectomy remains the gold standard for management of gallstones. The surgical access of laparoscopic cholecystectomy accomplished by Mouret in 1987 allows for a reduction in operative trauma, hospital stay, postoperative pain and convalescence. These factors permit a faster return to normal activities. Today, laparoscopic cholecystectomy is performed in almost all medical centers around the world; however, the procedure is not free of complications. The objective of this study was to analyze our first 1000 cases of laparoscopic cholecystectomy, giving emphasis to the morbidity and mortality of the procedure.

Influence of vanadate on glycolysis, intracellular sodium, and pH in perfused rat hearts.

Vanadium compounds have been shown to cause a variety of biological and metabolic effects including inhibition of certain enzymes, alteration of contractile function, and as an insulin like regulator of glucose metabolism. However, the influence of vanadium on metabolic and ionic changes in hearts remains to be understood. In this study we have examined the influence of vanadate on glucose metabolism and sodium transport in isolated perfused rat hearts. Hearts were perfused with 10 mM glucose and varying vanadate concentrations (0.7-100 microM) while changes in high energy phosphates (ATP and phosphocreatine (PCr)), intracellular pH, and intracellular sodium were monitored using 31P and 23Na NMR spectroscopy. Tissue lactate, glycogen, and (Na+, K+)-ATPase activity were also measured using biochemical assays. Under baseline conditions, vanadate increased tissue glycogen levels two fold and reduced (Na+, K+)-ATPase activity. Significant decreases in ATP and PCr were observed in the presence of vanadate, with little change in intracellular pH. These changes under baseline conditions were less severe when the hearts were perfused with glucose, palmitate and beta-hydroxybutyrate. During ischemia vanadate did not limit the rise in intracellular sodium, but slowed sodium recovery on reperfusion. The presence of vanadate during ischemia resulted in attenuation of acidosis, and reduced lactate accumulation. Reperfusion in the presence of vanadate resulted in a slower ATP recovery, while intracellular pH and PCr recovery was not affected. These results indicate that vanadate alters glucose utilization and (Na+, K+)-ATPase activity and thereby influences the response of the myocardium to an ischemic insult.

Colocalization of estrogen and progesterone receptors with an estrogen-regulated heat shock protein in paraffin sections of human breast and endometrial cancer tissue.

We have studied by immunocytochemistry and monoclonal antibodies the presence and localization of estrogen receptors, progesterone receptors, and a 24-kD estrogen-regulated heat shock protein in biopsies from breast and endometrial cancer patients. Three different tissue processing protocols were used to colocalize the antigens in the same tissue sections: a) frozen sections, b) formalin fixation with routine paraffin embedding, and c) picric acid-formaldehyde (PAF) fixation with a rapid embedding in paraffin. Frozen sections showed good receptor staining but poor 24-kD protein immunoreactivity, while routine paraffin sections (with or without DNase pretreatment) were inadequate to reveal the nuclear receptor proteins at the same level seen in frozen sections. On the other hand, all three proteins could be detected satisfactorily in PAF-fixed paraffin-embedded tissue. Using this procedure we were able to visualize 24-kD protein and estrogen receptor or progesterone receptor in individual cells in paraffin sections. The study revealed that in all of the estrogen receptor positive breast and endometrial tumor samples, almost 90% of the cells expressing the cytoplasmic 24-kD protein contained estrogen receptor in the cell nucleus. In contrast, 24-kD immunoreactive cells did not express progesterone receptors in almost 40% of the progesterone receptor positive tumor samples.

Multinuclear NMR study of the interaction of vanadate with mononucleotides, ADP, and ATP.

The interaction of vanadate with 5'-mononucleotides, ADP, ATP, and various molecules containing some of their chemical moieties was studied in aqueous solution in the pH region of 5-9 using proton, 13C, 31P, and 51V nuclear magnetic resonance (NMR) spectroscopy. All the compounds studied formed noncyclic vanadate esters through interaction of monovanadate or divanadate with the hydroxyl groups of the ribose ring. Noncyclic anhydrides were also formed with the phosphate groups of ribose 5-phosphate, the mononucleotides, ADP, ATP, phosphate, pyrophosphate, and tripolyphosphate. In particular, ADP and ATP analogs resulted from AMP (AMPV and AMPV2) and from ADP (ADPV). Cyclic esters of trigonal bipyramidal geometry resulted from the interaction of vanadate with two ribose ring cis hydroxyl groups. AMP, CMP, and UMP formed two such complexes of 1:1 and 1:2 stoichiometries, similar to what has been observed for uridine and other nucleosides. However, 2'-deoxy-AMP does not yield this type of complexes. ADP and ATP also form similar cyclic ester complexes with vanadate, which does not chelate their pyrophosphate and tripolyphosphate moieties. Nevertheless, the separate pyrophosphate (PP) and tripolyphosphate (PPP) ligands form cyclic anhydrides of octahedral geometry with vanadate. However, their binding to vanadate is weaker than that of the ribose ring of nucleotides. Competition experiments between ethylene glycol and phosphate (P), pyrophosphate (PP), or tripolyphosphate (PPP) show that the relative strength of the interaction of these ligands with vanadate is PP greater than ethylene glycol greater than PPP greater than P.

Interaction of vanadate with monosaccharides and nucleosides: a multinuclear NMR study.

Proton, 13C and 51V nuclear magnetic resonance spectroscopy has been used to study the interaction of vanadate with several molecules containing more than one hydroxyl group, including various aldoses and nucleosides. The aldoses D-mannose and D-ribose mainly form tridentate complexes, of trigonal bipyramidal geometry, with vanadate at pH 7. These sugars use three consecutive hydroxyl groups, cis to each other, of their pyranose forms to bind vanadate in those cyclic triesters. Other aldoses, like D-glucose, which do not have this unique structural characteristic, do not form tridentate complexes, but can form weaker bidentate cyclic diesters using two consecutive pyranose cis hydroxyl groups. Of course, the pyranose forms of D-mannose and D-ribose, as well as the furanose form of D-ribose, also yield cyclic diesters of vanadate. All these aldoses form weak monodentate noncyclic monoesters of tetrahedral geometry using a single hydroxyl group. The nucleosides uridine, cytidine and adenosine form two complexes of trigonal bipyramidal geometry with vanadate. In these complexes, having 1:1 and 2:1 ligand-to-metal stoichiometries, the nucleosides form cyclic diesters with vanadate using their C2, and C3, hydroxyl groups.

1H and 31P NMR study of the interaction of molybdate with the nucleotides adenosine 5'-diphosphate and adenosine 5'-triphosphate.

ADP and ATP form in acidic aqueous solutions strong complexes with Mo(VI) oxocations in different stoichiometries. Complexation occurs predominantly, if not exclusively, through the phosphate groups of the nucleotides.