Binding and removal of sulfate, phosphate, arsenate, tetrachloromercurate, and chromate in aqueous solution by means of an activated carbon functionalized with a pyrimidine-based anion receptor (HL). Crystal structures of [H3L(HgCl4)]·H2O and [H3L(HgBr4)]·H2O showing anion-π interactions.

Binding of anions of great environmental concern such as SO(4)(2-), PO(4)(3-), AsO(4)(3-), HgCl(4)(2-), and CrO(4)(2-) by the protonated forms of a tren-like (tren = tris(2-aminoethyl)amine) ligand (HL) functionalized with a pyrimidine residue was studied by means of potentiometric measurements and isothermal titration calorimetry (ITC) affording log K, ΔH°, and TΔS° values for the formation of the relevant complexes. The complexes show high to very high stability due to the particular topology and electronic properties of the ligand which is able to use two separated coordination environments to host the anions, the protonated tren site where electrostatic and hydrogen bond interactions are operating, and the pyrimidine ring which may act via anion-π interaction. A contribution of -8.9 ± 0.4 kJ/mol for pyrimidine-anion interaction in water was derived for SO(4)(2-) binding. The crystal structures of [H(3)L(HgCl(4))]·H(2)O (1), [H(3)L(HgBr(4))]·H(2)O (2), and that previously reported for [H(3)L(CdI(4))], clearly show these binding features in the solid state. A hybrid AC-HL material obtained by adsorption of HL on commercial activated carbon (AC) was used to study the removal of these anions from water. AC-HL shows enhanced adsorption capacity toward all the anions studied with respect to AC. This behavior is ascribed to the stronger interaction of anions with the HL function of AC-HL than with the Cπ-H(3)O(+) sites of the unfunctionalized AC.

Management of calcific uremic arteriolopathy (calciphylaxis) with a combination of treatments, including hyperbaric oxygen therapy.

Calcific uremic arteriolopathy (CUA) is a rare but serious complication of end-stage renal disease presenting as painful cutaneous lesions and progressing to non-healing ulcers and gangrene. This syndrome is associated with calcium and phosphorus deposits within small arteries of the skin. The pathognomonic lesion is vascular calcification with intimal arterial hypertrophy and superimposed small-vessel thrombosis. The condition is being increasingly recognized and reported as a contributing factor to death in dialysis patients, with secondary infection and sepsis as the major cause of mortality. No standard treatment has been established for this syndrome. We present the therapeutic approach employed in two patients, which successfully resulted in healing of the lesions, using a combination of measures to control the factors potentially related to development of CUA and hyperbaric oxygen therapy.

Surface EMG and torsion measurements during snow skiing: laboratory and field tests.

The relationship between mean rectified EMG (MREMG) measured with surface electrodes and the longitudinal torsion of the lower extremity was investigated in laboratory and snow skiing experiments. Linear regression of the MREMG from the gluteus medius and the peroneus longus with the torsion measured at the foot in the laboratory tests showed that torsion can be predicted with correlation coefficients greater than 0.95 and with a standard deviation less than 5 Nm over all knee flexions and weight bearing. A similar correspondence between MREMG and torsion during skiing does not exist. MREMG is dominantly correlated to posture and body position control functions in skiing. During falling, during ski binding release, and during possible injury sustaining situations, the MREMG was always relatively large, but it was not distinguishable from that associated with smaller torsion of the lower extremity.

Neurohumoral correlates of sleep: further biochemical and physiological characterization of sleep perfusates.

Twenty cats were prepared surgically with electrodes for recording the EEG, Eye Movements and EMG and a push-pull cannula system in the midbrain reticular formation (MRF) allowing the extraction of perfusates during wakefulness or REM sleep. Proteins in the perfusates were analyzed by Isoelectric Focusing (IEF) polyacrylamide gels and Sodium Dodesyl Sulphate (SDS) slab gels. In addition analysis of glycoproteins was done by gas chromatography. In some cats the contribution of cerebrospinal fluid (CSF) proteins to perfusate proteins from brain tissue was studied by intraventricular injections of labelled leucine. The effect of sleep alterations on the protein cycle during sleep and wakefulness was also studied. The results of these experiments showed that most of the proteins in the perfusates are acidic, and that REM sleep perfusates contain 2 proteins M.W. 73.000 and 45.000 not present in awake perfusates, CSF or serum. It was also shown that CSF proteins do not appear to contribute to the proteins in perfusates, and that altering the sleep wake cycle, induces changes in the rhythm of protein release in perfusates. It is suggested that some relatively large polypeptides may participate in the regulation of REM sleep.

[Phenotypic expression of Lp(a) in Spanish children and adolescents]. / Expresión fenotípica de la Lp(a) en niños y adolescentes españoles.

BACKGROUND: To know the distribution of phenotypes Lp(a) in an young population. METHODS: Lipoprotein levels, lipoprotein(a), apolipoproteins and the Lp(a) phenotypes were determined in 105 children, selected according to their cholesterol concentrations. RESULTS: The Lp(a) concentrations were significantly higher in group with low molecular weight respect to group with high molecular weight. The most frequent isoform was S3. CONCLUSIONS: The Lp(a) concentrations correlate inversely with the molecular weight of Apo(a) isoforms.

Identification and characterization of pipecolic acid binding sites in mouse brain.

Pipecolic acid (PA, piperidine-2-carboxylic acid) is the major product of lysine metabolism in the mammalian brain (Giacobini et al., 1980). In this study we have characterized the binding of [3H]PA to P2 fraction membranes and its distribution in the mouse brain. The binding was found to be saturable (70 nM), temperature and Na+ and Cl- dependent. A high affinity binding site with an apparent KD of 33.2 nM and a Bmax of 0.2 pmol/mg protein was demonstrated. The regional distribution of [3H]PA specific binding in mouse brain showed the highest concentration in cerebral cortex, thalamus and olfactory bulb. Unlabeled PA (10(-3)-10(-11) M) displaced specific binding of [3H]PA in a concentration dependent manner. Out of several substances tested, only proline showed a similar pattern of displacement. Pre-incubation of the membrane preparation with GABA (10(-3)-10(-11) M) resulted in either an increase or decrease of [3H]PA binding depending on the concentrations of GABA and PA. These results suggest a modulatory action of GABA on PA binding sites. The postnatal development of [3H]PA specific binding was studied in the whole brain of the mouse. [3H]Pipecolic acid binding increased progressively (8-fold) from one day after birth to 16 days. Following this developmental peak, the binding decreased gradually to 30 days at which age, adult values were attained.

Simultaneous determination of fat-soluble vitamins and provitamins in dairy products by liquid chromatography with a narrow-bore column.

A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of vitamins A, D2, D3, E and K1, retinyl acetate, retinyl palmitate, tocopherol acetate, ergosterol and 7-dehydrocholesterol in milk and butter. Narrow-bore columns are recommended because this alternative provides a good separation and efficiency, plus greater economy and sensitivity. Detection limits for individual vitamins range from 0.14 to 6.9 ng. All vitamins are separated in less than 33 min. For the simultaneous determination of these vitamins and provitamins we use two sample pre-treatment methods, a liquid-liquid extraction with hexane or a solid-phase extraction with a C18 cartridge. Recovery studies show good results for all solutes (84-108% and 85-108% for milk and butter, respectively) and the intra-day coefficients of variations range from 1.6 to 4.5%. These methods permit the simple determination of fat-soluble vitamins using a small sample volume.

Determination of acaricides in honey by liquid chromatography with ordinary, narrow-bore, and microbore columns.

Narrow-bore and microbore columns packed with octadecylsilane were used to compare their sensitivity and efficiency in the separation of coumaphos, fluvalinate, bromopropylate, and 4,4'-dibromobenzophenone from honey with those of ordinary columns. The best sensitivity for acaricides was accomplished by using a 150 mm × 0.32 mm i.d., 5 µm Spherisorb ODS-2 capillary column, methanol-water (90:10 v/v) as the mobile phase, and 5 µL/min as the flow rate. Detection limits for individual acaricides using a UV detection range from 0.40 to 0.74 µg/kg of honey were comparable to those obtained by gas chromatography using an electron capture detector. All acaricides were separated in <12 min. The coefficients of variations on real samples were <6.2%.

[A comparative study of technics for the diagnosis of the human immunodeficiency virus in infants under 15 months by: viral cultivation, the polymerase chain reaction and antigen p24]. / Estudio comparativo de técnicas para el diagnóstico del virus de la inmunodeficiencia humana en niños menores de 15 meses por: cultivo viral, reacción en cadena de la polimerasa y antígeno p24.

The objective of this study was to compare the polymerase chain reaction (PCR), virus culture (VC) and antigen detection (AG), assays which can be used for the early diagnosis of vertically transmitted HIV-1 infection in infants under 15 months of age, when a diagnosis cannot be based on seropositivity because of maternal antibody persistence. Thirty-nine children born to HIV-1-seropositive mothers were evaluated by the three techniques. The children were then followed to at least 18 months of age. The p24 antigen was measured in plasma and HIV proviral DNA was determined in peripheral blood mononuclear cells after amplification by PCR. Prime pairs from three different regions of the proviral genome were used for the PCR tests. We found that in the first evaluation, 15 (100%) of the children who later developed clinical symptoms were positive by PCR analysis, 14 (93.3%) by the initial VC assay and only 8 (53.3%) by the p24 antigen assay. In conclusion, PCR and VC assays were found to have higher sensitivity than the p24 antigen assay for the diagnosis of HIV-1 infection. In addition, p24 antigenaemia was shown to be useful in predicting the onset of the disease. This study shows that the PCR test represents a more reliable and faster alternative to viral culture for the diagnosis of pediatric HIV infection.

[Genetic predisposition to develop insulin-dependent diabetes mellitus. A population study in Santiago and Temuco, Chile]. / Predisposición genética para desarrollar diabetes mellitus insulino-dependiente. Estudio en población de Santiago y Temuco, Chile.

Insulin-dependent diabetes mellitus (IDDM) is strongly associated with particular HLA-DQ alpha/beta markers in white population. The heterodimers conformation composed of a DQ alpha chain with an arginine at residue 52 (Arg52) combined to a DQ beta chain lacking an aspartic acid at residue 57 (non Asp57) increase markedly the risk to develop IDDM. To confirm this association, 63 IDDM patients from Santiago de Chile registry, 20 IDDM patients from Temuco registry and 74 unrelated healthy non diabetic control subjects were studied. With polymerase chain reaction (PCR) and sequence specific oligonucleotide probes the individuals were typed for their HLA-DQA1 and DQB1 alleles, their DQA1/DQB1 genotype and heterodimers conformation were compared. In diabetic population both markers Arg52 homocygote and non Asp57 homocygote were markedly increased regard to control subjects (R/R: 0.76 and 0.85 vs 0.33; ND/ND: 0.78 and 0.75 vs 0.50, p < 0.05). A high relative risk (RR) was determined for both homocygote markers in IDDM groups. Arg52 DQ alpha (R)/non Asp57 DQ beta (ND) heterodimers were strongly associated with susceptibility to IDDM. A high RR was observed in patients with four susceptibility DQ heterodimers (RR1: 13.7 in IDDM-Santiago and RR2: 18.6 in IDDM-Temuco, p < 0.00003). The HLA-DQ alpha/beta markers and their risk heterodimers are increased in our diabetic population and could be considered as susceptibility markers to develop IDDM.

N-(6-Amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl) derivatives of glycine, valine, serine, threonine and methionine: interplay of molecular, molecular-electronic and supramolecular structures.

In each of N-(6-amino-3, 4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)valine, C(10)H(15)N(5)O(4) (3) (orthorhombic, P2(1)2(1)2(1)), N-(6-amino-3, 4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)serine monohydrate, C(8)H(11)N(5)O(5).H(2)O (4) (orthorhombic, P2(1)2(1)2(1)), and N-(6-amino-3, 4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)threonine, C(9)H(13)N(5)O(5)(5) (monoclinic, P2(1)), the C-nitroso fragments exhibit almost equal C-N and N-O bond lengths: the C-N range is 1. 315 (3)-1.329 (3) A and the N-O range is 1.293 (3)-1.326 (3) A. In each compound there are also very short intermolecular O-H.O hydrogen bonds, in which carboxyl groups act as hydrogen-bond donors to the nitrosyl O atoms: the O.O distances range from 2.440 (2) to 2. 504 (4) A and the O-H.O angles lie between 161 and 163 degrees. An interpretation of the relationship between the unusual intramolecular bond lengths and the very short intermolecular hydrogen bonds has been developed based on database analysis and computational modelling. In each of (3)-(5) there is an extensive network of intermolecular hydrogen bonds, generating three-dimensional frameworks in (3) and (5), and two-dimensional sheets in (4).