Novel microporous europium and terbium silicates

The synthesis and structural characterization of the first examples of microporous europium(III) and terbium(III) silicates (Na(4)K(2)X(2)Si(16)O(38) x 10H(2)O, X = Eu, Tb) are reported. The structure of these solids was solved by powder X-ray diffraction ab initio (direct) methods and further characterized by chemical analysis (EDS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), (23)Na and (29)Si magic-angle spinning (MAS) NMR, and luminescence spectroscopy. Both materials display interesting photoluminescence properties and present potential for applications in optoelectronics. This work illustrates the possibility of combining in a given silicate microporosity and optical activity.

Determination of the degree of acetylation of chitin materials by 13C CP/MAS NMR spectroscopy

13C CP/MAS NMR spectroscopy has been shown to be a powerful tool to quantify the degree of acetylation of chitin and chitosan. In order to optimise the parameters which afford quantitative 13C cross-polarisation magic-angle spinning NMR spectra, a detailed relaxation study has been carried out on selected chitin and deacetylated chitin samples. A relaxation delay of 5 s and a contact time of 1 ms have been found to yield quantitative NMR spectra of samples with deacetylation degree values of 0.68 and 0.16. The measured spin-lattice relaxation times in the rotating frame, T(1rhoH), are in the range 6.4-8.9 ms for chitin and 4.3-7.3 ms for deacetylated chitin, while TCH values for both samples are very similar and range from 0.03 to 0.19 ms. Spin-counting experiments indicate that, within experimental error, all carbon is detected by NMR indicating that the samples studied contain no (or very few) paramagnetic centres.

Clinical, epidemiologic, and virologic features of dengue in the 1998 epidemic in Nicaragua

From July to December 1998, a hospital- and health center-based surveillance system for dengue was established at selected sites in Nicaragua to better define the epidemiology of this disease. Demographic and clinical information as well as clinical laboratory results were obtained, and virus isolation, reverse transcriptase-polymerase chain reaction, and serologic assays were performed. World Health Organization criteria were used to classify disease severity; however, a number of patients presented with signs of shock in the absence of thrombocytopenia or hemoconcentration. Therefore, a new category was designated as "dengue with signs associated with shock" (DSAS). Of 1,027 patients enrolled in the study, 614 (60%) were laboratory-confirmed as positive cases; of these, 268 (44%) were classified as dengue fever (DF); 267 (43%) as DF with hemorrhagic manifestations (DFHem); 40 (7%) as dengue hemorrhagic fever (DHF); 20 (3%) as dengue shock syndrome (DSS); and 17 (3%) as DSAS. Interestingly, secondary infection was not significantly correlated with DHF/DSS, in contrast to previous studies in Southeast Asia. DEN-3 was responsible for the majority of cases, with a minority due to DEN-2; both serotypes contributed to severe disease. As evidenced by the analysis of this epidemic, the epidemiology of dengue can differ according to geographic region and viral serotype.

(MeLi)4(dem)1.5]infinity] and [(thf)3Li3M3[(NtBu)3S--how to reduce aggregation of parent methyllithium

Organolithium compounds play the leading role among the organometallic reagents in synthesis and in industrial processes. Up to date industrial application of methyllithium is limited because it is only soluble in diethyl ether, which amplifies various hazards in large-scale processes. However, most reactions require polar solvents like diethyl ether or THF to disassemble parent organolithium oligomers. If classical bidentate donor solvents like TMEDA (TMEDA= N,N,N',N'tetramethyl-1,2-ethanediamine) or DME (DME=1,2-dimethoxyethane) are added to methyllithium, tetrameric units are linked to form polymeric arrays that suffer from reduced reactivity and/or solubility. In this paper we present two different approaches to tune methyllithium aggregation. In [[(MeLi)4(dem)1,5)infinity] (1; DEM = EtOCH2OEt, diethoxymethane) a polymeric architecture is maintained that forms microporous soluble aggregates as a result of the rigid bite of the methylene-bridged bidentate donor base DEM. Wide channels of 720 pm in diameter in the structure maintain full solubility as they are coated with lipophilic ethyl groups and filled with solvent. In compound 1 the long-range Li3CH3...Li interactions found in solid [[(MeLi)4]infinity] are maintained. A different approach was successful in the disassembly of the tetrameric architecture of [((MeLi)4]infinity]. In the reaction of dilithium triazasulfite both the parent [(MeLi)4] tetramer and the [[Li2[(NtBu)3S]]2] dimer disintegrate and recombine to give an MeLi monomer stabilized in the adduct complex [(thf)3Li3Me-[(NtBu)3S]] (2). One side of the Li3 triangle, often found in organolithium chemistry, is shielded by the tripodal triazasulfite, while the other face is mu3-capped by the methanide anion. This Li3 structural motif is also present in organolithium tetramers and hexamers. All single-crystal structures have been confirmed through solid-state NMR experiments to be the same as in the bulk powder material.

[Intracranial hemangioma]

A case of intracranial hemangioma in a neonate is described by the authors. The rarity of the condition raised differential diagnosis problems.

Patterns of haplotype diversity within the serpin gene cluster at 14q32.1: insights into the natural history of the alpha1-antitrypsin polymorphism

The levels of haplotype diversity associated with different alpha1-antitrypsin (PI) alleles were assessed by the analysis of three microsatellites located within or close to corticosteroid-binding globulin (CBG), alpha1-antitrypsin [PI-(TG)n] and protein C inhibitor [PCI-(TG)n] loci in three populations with different historic backgrounds: Portugal, the Basque Country and São Tomé Príncipe (Gulf of Guinea). Unlike the more distant PCI-(TG)n repeat, allelic variation at PI-(TG)n reflected distinct phases of mutational recovery of microsatellite diversity around different founder alleles and showed a considerable differentiation between alpha1-antitrypsin protein variants. In accordance with population history, the Basque sample presented overall reduced levels of microsatellite variation. The African sample, although presenting the highest PCI-(TG)n diversity, showed a lineage-specific reduction in PI-(TG)n heterozygosity within the oldest M1Ala213 variant that could have been caused by (1) selection at a closely linked locus or (2) biases in the microsatellite mutation process leading to a stable equilibrium distribution. Age estimates of alpha1-antitrypsin variants based on microsatellite variation suggest that the Z deficiency allele appeared 107-135 generations ago and could have been spread in Neolithic times. The S mutation has an older 279- to 470-generation age, indicating that its high frequencies in Iberia did not result from a recent bottleneck and that PI*S could have originated in this region. M2 and M3 types had lower age estimates than would be expected from their wide geographical distributions, suggesting that their dispersion in Europe might have been preceded by important bottlenecks.

Allelic affinities between the F13A common gene products inferred by the analysis of an (AAAG)n STR polymorphism within the 5' untranslated region

Factor XIII a subunit (F13A) is the last enzyme in the blood coagulation cascade. It is characterized by extensive genetic polymorphism defined by 4 common alleles, F13A*1A, 1B, 2A and 2B and a few rare variants, some responsible for severe coagulation deficiencies. In order to infer the evolutionary affinities between the common F13A alleles we have applied PCR techniques to study, in a Northern Portuguese sample, a short tandem repeat polymorphism located within the 5' untranslated region of the F13A gene. The analysis of the molecular heterogeneity within the F13A gene products revealed that the four biochemical variants shared very similar, truncated, distributions of STR alleles and showed no signs of predominant haplotypic associations. These findings seem to support both the inferences that intragenic recombination played an important role in the generation of molecular diversity within each of the four main F13A alleles and that all the four F13A alleles must be rather old. Molecular heterogeneity levels allowed the identification of 1B as the oldest F13A allelic state, and 2A as the most recently generated allele, but were not different enough to accurately track the divergence of alleles 1A and 2B. However, additional analysis of linkage disequilibrium patterns indicates that 1B-->2B-->1A-->2A is the most likely evolutionary order of appearance of F13A main protein alleles, confirming and extending a previous hypothetical model inferred from their molecular features.

Structural characterization of glassy phases in the system Na2O-Ga2O3-P2O5 by MAS-NMR, EXAFS and vibrational spectroscopy. I. Cations coordination

The cationic coordinations of phosphate based gallium sodium glasses in the system Na2O-Ga2O3-P2O5 have been studied by several techniques (71Ga and 23Na MAS-NMR, EXAFS and vibrational spectroscopies) in order to study the relationship between the structure and the chemical composition. We found that three different environments are available for the gallium ions while it is very difficult to get accurate information on the sodium coordinations. Our data show that in orthophosphate glasses, gallium is mainly tetrahedral but when the mean phosphate chain length increases, its coordination becomes more and more octahedral. In these glassy structure, it becomes then possible to dissolve large amounts of typically octahedral cations like Fe3+ or Cr3+.

Structural characterization of glassy phases in the system Na2O-Ga2O3-P2O5 by MAS and solution NMR and vibrational spectroscopy: II. Structure of the phosphate network

The structure of the phosphate network of glasses in the system Na2O-Ga2O3-P2O5 has been investigated as a function of the Na/Ga molar ratio and the phosphate composition corresponding to a mono, di, tri, tetra and meta phosphate stoichiometry. The glass is made of phosphate molecular groups of different lengths linked by the cations with rather ionic (Na) or more covalent (Ga) bonds except in the case of the orthophosphate composition for which we only found isolated PO4(3-) ions. The vibrational spectra are sensitive to composition variations but the band width and the couplings between the different groups prevent any quantitative determination. 31P MAS-NMR gives an in-situ information on the P environment in the glass but the signals are often large and ill defined so that the assignment is not at all straightforward. On the other hand, 31P solution NMR gives sharper signals, allowing more quantitative determinations but the dissolution process always introduces some indeterminacy on the real glass structure which can be minimized by a careful preparation of the solution.

Haplotype analysis of the apolipoprotein E and apolipoprotein C1 loci in Portugal and São Tomé e Príncipe (Gulf of Guinea): linkage disequilibrium evidence that APOE*4 is the ancestral APOE allele

The joint distributions of phenotypes from the apolipoprotein E gene (APOE) and from a closely linked restriction site polymorphism at the apolipoprotein C1 locus (APOC1) were studied in population samples from Portugal and São Tomé e Príncipe (Gulf of Guinea), a former Portuguese colony that was originally populated by slaves imported from the African mainland. The frequencies of the APOE alleles (*2, *3, and *4) in Portugal and São Tomé fitted the ranges of variation generally observed in European and African populations, respectively. Haplotype analysis showed that in both populations the strength of linkage disequilibrium was highest for the APOE*2 allele and lowest for the APOE*4 allele, suggesting that the origin of the APOE alleles followed a 4-->3-->2 pathway and thus providing independent confirmation of the results from sequence homology studies with nonhuman primates. In accordance with global trends in the distribution of human genetic variation, the European sample from Portugal presented more intense linkage disequilibrium between APOE and APOC1 than the African sample from São Tomé where, despite the short 4-kb distance that separates the 2 loci, the level of association between the APOC1 alleles and APOE*4 was nonsignificant.

Solid-state single and triple-quantum 93Nb MAS NMR studies of ferroelectric Pb(Mg1/3Nb2/3)O3 and a related pyrochlore

Pb(Mg1/3Nb2/3)O3 (PMN), a well-known relaxor ferroelectric material, and a related pyrochlore phase have been studied by single- and triple-quantum 93Nb MAS NMR spectroscopy. The assignment of the NMR resonances has been attempted.

Adenosine deaminase polymorphisms at the protein and DNA levels

Adenosine deaminase (ADA, E.C. 3.5.4.4) exhibits a well-known polymorphism at the protein level. We have studied ADA and an STR polymorphism exhibiting variation of a TTTA repeat motif at intron 3 of the ADA gene in random samples from northern Portugal (N = 218) and southwestern Germany (N = 114). The ADA phenotype distribution and population data on the worldwide distribution of ADA favor recurrent mutation as an explanation for the maintenance of the ADA*2 gene product at polymorphic frequencies.

Identification of a novel R21X mutation in the liver-type arginase gene (ARG1) in four Portuguese patients with argininemia

Argininemia is a rare autossomal recessive disorder caused by deficiency in the cytosolic liver-type arginase enzyme (L-arginine urea-hydrolase; E.C. 3.5.3.1). In order to investigate the molecular basis for argininemia in four unrelated Portuguese patients (two from northern Portugal and two from Madeira Island) we performed a DNA sequence analysis of all the exons and exon/intron boundaries of the liver-type arginase gene (ARG1). All patients were found to be homozygous for a newly identified C ->T transition in codon 21 (exon 2) substituting arginine for a premature stop codon (R21X: CGA to TGA) and generating a NlaIII restriction site. Restriction digestion following PCR amplification of ARG1 exon 2 confirmed the presence of the mutation.

Very high-resolution 1H MAS NMR of a natural polymeric material

The use of ultrafast magic angle spinning (> 30 kHz) in tandem with delayed echo acquisition is shown to yield very high-resolution lH MAS NMR spectra of complex natural organic materials. For the first time, very high-resolution 1H MAS NMR spectra are reported for cork and wood components, two natural materials with great economic importance. The effect of the spinning rate on the 1H NMR spectra was evaluated with single-pulse acquisition and delayed-echo acquisition. The delayed-echo acquisition spectra presented linewidths as sharp as 67 and 25 Hz. The narrow peaks, characterised by proton spin-spin and spin-lattice relaxation, were assigned to the isotropic chemical shifts and the general spectral features were shown to correlate with the sample chemical structure. The tentative assignments of cork 1H MAS NMR signals were presented.

Identification in Portugal and Brazil of a mtDNA lineage containing a 9-bp triplication of the intergenic COII/tRNALys region

Although the deletion of one of the 9-bp repeats in region V of mitochondrial DNA is very common in Asians, Asian-derived populations and Africans, the triplication of the 9-bp segment was described only a few times, mostly on individuals from Asian origin. Here, we report for the first time the presence of the 9-bp triplication in Europeans. The triplication was initially found in one Brazilian individual. Sequencing of the hypervariable segments I (HVSI) and II (HVS2) of the control region and RFLP analysis of the coding region classified the mtDNA as belonging to the European haplogroup H. Since white Brazilians are predominantly of Portuguese descent, we screened 96 unrelated Northern Portuguese for the 9-bp triplication and found its presence in two of them (2.1%). One of these had an mtDNA haplotype identical to that of the Brazilian individual, while the other differed in a single base change in HVS2. The fact that the 9-bp triplication has reached polymorphic frequencies in Northern Portugal and that it has apparently differentiated into at least two lineages defined by the mutuation in HVS2 suggests that it probably occurred a long time ago.

Pancreatitis and primary hyperparathyroidism: forty cases

BACKGROUND

Pancreatitis is associated with primary hyperparathyroidism (PHPT) in 1.5-7% of cases. The relationship of cause and effect between the two diseases has been debated.

METHODS

To evaluate this relationship, the clinical, biochemical and pathological data on 1435 patients operated on for hyperparathyroidism (HPT) over the past 30 years were retrospectively reviewed. A total of 1224 of these patients had biologically proven and cured PHPT and 211 patients had renal HPT (RHPT). The diagnosis of pancreatitis (PTS) was based on a high serum amylase level and/or abnormalities on ultrasound or computed tomography (CT) scan explorations. Only patients without biliary stones were included in the PTS group associated with HPT.

RESULTS

A total of 3.2% (n = 40) of patients with PHPT had PTS, which was acute in 18 cases, subacute in 8 cases and chronic in 14 cases. This rate of PTS is higher than in a random hospital population. Surgical cure of HPT was followed by the spontaneous healing of 17/18 acute PTS, whereas six of the 22 patients with subacute or chronic PTS developed complications due to the evolution of their disease (diabetes, pancreatic duct stenosis treated by surgery). A single diseased gland was found in 27 patients with PTS, which is in favour of primary parathyroid disease, being responsible for, and not a consequence of, PTS. Only the serum calcium (13.0 vs 12.1 g/dL) level was significantly increased in PHPT patients with PTS, when compared to those without PTS. The calcium level is probably of major importance in the development of PTS, which was never encountered in 211 patients with RHPT, who had low calcium and high PTH levels.

CONCLUSIONS

The data suggest that (i) the PTS-PHPT association is not incidental; (ii) PTS is the consequence and not the cause of PHPT; (iii) hypercalcaemia seems to be a major factor in the development of PTS in PHPT patients; and (iv) cure of PHPT leads to the healing of acute PTS, whereas it does not affect the evolution of subacute and chronic PTS.

A 13C solid state nuclear magnetic resonance spectroscopic study of cork cell wall structure: the effect of suberin removal

Solid state 13C NMR measurements of cork, before and after suberin removal, showed that aliphatic suberin is spatially separated from carbohydrate and lignin and experiences higher motional freedom. Two types of chain methylenes, differing in chemical shift and in dynamic properties, were identified in aliphatic suberin. Experimental evidence indicated that the more motionally hindered methylenes are those situated nearer the linkages of aliphatic suberin to the cell wall. These linkages were shown to involve -CH2O- groups, probably engaged in ester linkages to phenylpropane units and carbohydrate C6 carbons. Spectral intensity changes indicated that, during the first steps of alkaline desuberization, these linkages are broken and the shorter aliphatic suberin chains removed. Longer chains require hydrolysis of the ester linkages within the chains and are removed upon stronger alkaline treatment. T1(C), T1 rho (H) and T1 rho (C) relaxation times have shown that the removal of suberin from cork leads to a motionally restricted and more compact environment, on the megahertz and mid-kilohertz timescales. The properties of cork suberin showed that suberin organization in cork is distinct from that in potato tissue.

Solid-state NMR studies of interstitial phosphorus atoms in rhodium carbonyl clusters

Pure samples and as-prepared mixtures of Rh9 and Rh10 carbonyl clusters with interstitial P atoms have been studied quantitatively by 31P MAS and 1H-31P CP/MAS NMR. Information on the 31P chemical shift tensor of the Rh9 and Rh10 clusters has been derived from spinning sideband simulations. The chemical shift anisotropy is slightly larger in the Rh10 clusters (340-400 ppm) than in the Rh9 clusters (230-300 ppm), while the asymmetry parameters are similar (eta = 0.1-0.4). The results contribute to the understanding of the relationship between the shielding anisotropy and the structure of the cluster cavity.

Analysis of the allelic diversity of a (CA)n repeat polymorphism among alpha 1-antitrypsin gene products from northern Portugal

The level of molecular heterogeneity associated with alpha 1-antitrypsin gene products was assessed in the population of northern Portugal using three restriction fragment length polymorphisms (RFLPs) corresponding to specific amino acid substitutions and a highly variable (CA)n repeat polymorphism located at the 5' end of the PI gene. The allelic affinities inferred from the analysis of the DNA polymorphisms essentially agree with the evolutionary pattern proposed for the PI gene products on the basis of their amino acid sequences. PI*Z can be considered the most recent common PI allele and was found to be associated with the same predominant haplotype previously reported in northern European populations, thus confirming the hypothesis that most European Z alleles are derived from a single mutation. However, a rare deficient variant that is the likely result of a recurrent Z mutation on an M2 or M4 background was additionally observed. PIS was also found to be associated with a strongly predominant haplotype and seems to be the second most recent PI common allele, while M2 and M3 show weaker associations, suggesting more ancient origins of their corresponding mutations. M1Ala213 and M1Vat213 display more homogeneous (CA)n allele frequency distributions, M1Ala213 representing the most ancient PI allele as inferred from its highest variance in (CA)n allele length.

Anterior evacuation of a spontaneous cervical epidural hematoma

The case of a spontaneous cervical epidural hematoma treated by anterior corporectomy and arthrodesis is reported. An anterior approach is preferable when an epidural hematoma is anterior to the dural sac and when MRI shows an aspect of old clotted blood that can not be easily evacuated by a posterior laminectomy.

Transient bisalbuminemia: separation by isoelectric focusing of human albumin fractions linked to different numbers of benzylpenicilloyl groups

The behavior of modified human serum albumin (HSA) from penicillin-treated patients and in vitro conjugated samples was studied by isoelectric focusing in the absence and presence of 8 M urea. It is shown that samples classified as bisalbuminemic after separation under native conditions display a spectrum of several major bands with decreasing pIs when focusing is done in the presence of 8 M urea. In this spectrum, the distances between two consecutive major bands are as expected from a 2-unit charge difference. Since this result is compatible with the blockage of a lysine residue with a benzylpenicilloyl (BPO) group, each major band can be interpreted as representing an HSA fraction covalently linked to different numbers of benzylpenicilloyl groups. The separation methods presented therefore seem to constitute simple and reliable tools for a detailed assessment of the extent of BPO covalent binding to HSA both in vivo and in vitro.

13C solid-state nuclear magnetic resonance and Fourier transform infrared studies of the thermal decomposition of cork

The thermal decomposition of cork has been studied by Fourier transform infrared (FTIR) spectroscopy and 13C solid-state nuclear magnetic resonance (NMR) spectroscopy with cross-polarization and magic-angle spinning (CP-MAS), high-power 1H decoupling (HPDEC) and cross-polarization depolarization-polarization (CPDP). Waxes and other soluble components of cork begin to decompose at ca. 150 degrees C. This is accompanied by partial decomposition of suberin, probably initiated at the points of attachment to the cell wall. The carbohydrates begin to decompose at ca. 200 degrees C. The decomposition of lignin begins at 250-300 degrees C, while suberin undergoes further degradation. Significant amounts of coke are formed in the process. At 400 degrees C cork has been transformed into coke with traces of partially decomposed suberin. The thermal decomposition of cork is dependent on the calcination time, particularly in the 200-350 degrees C range.

Distribution of ACP1, AK1 and ALAD polymorphisms in northern Portugal

Red cell acid phosphatase (ACP1), adenylate kinase 1 (AK1), and aminolevulinate dehydratase (ALAD) polymorphisms were studied in a population sample from Northern Portugal. The gene frequency estimates found were: ACP1*A = 0.2825, ACP1*B = 0.6625, ACP1*C = 0.0547, ACP1*R = 0.0003 (N = 1517); AK1*1 = 0.9778, AK1*2 = 0.0213, AK1*3 = 0.0009 (N = 1081); ALAD*1 = 0.9094, ALAD*2 = 0.0906 (N = 1043).