Molecular characterization of G2m(n+) and G2m(n−) allotypes

Immunoglobulin (Ig) allotype typing is usually performed with serological methods based on hemagglutination inhibition. The recent development of molecular techniques has allowed the molecular typing of several Ig markers. The hinge, CH2, and CH3 domains of the G2 gene from six unrelated individuals (three G2m(n+) and three G2m(n–)) were amplified and cloned to establish the molecular basis of the G2m ⁿ⁺ and G2m ^n–. Comparison of the allele sequences revealed three changes: two (codons 308 and 437) are silent exonic substitutions, one is a G to A transition corresponding to an amino acid difference in position 282: Val (GTG) in G2m ^n–, Met (ATG) in G2m ⁿ⁺. These substitutions were identified via two approaches: 282 polymorphism, after digestion of a specific polymerase chain reaction product with Nla III followed by acrylamide electrophoresis; 308 and 437, by a dot-blot technique using allele-specific oligonucleotides. These molecular typing results correspond exactly to those obtained serologically; moreover, the three substitutions defining the G2m ⁿ⁺ and G2m ^n– alleles are always associated in a strict linkage disequilibrium.The nucleotide sequence data reported in this paper have been submitted to the EMBL nucleotide sequence database and have been assigned the accession numbers Z49801 and Z49802     

Dynamic behaviour of mucus glycoproteins — a 13C n.m.r. relaxation study

The motional dynamic behaviour of a mucus glycoprotein is investigated in aqueous solutions by performing T₁, T₂ and NOE measurements. In order to get an insight into the diverse functional groups most of the carbon atoms have been assigned which are well separated when using an observe frequency of 50.3 MHz. To figure out the influence of the formation of hydrogen bondings on the dynamic behaviour CP MAS spectra of the solid glycoprotein are performed. These measurements lead to the assumption that the hydroxymethylene groups of the various hexopyranoses are capable of forming essential intermolecular hydrogen bonds.     

Abundance and degree of dispersion of genomic d(GA) n ·d(TC) n sequences

Summary The abundance of d(GA) _n ·d(TC) _n tracts was determined in genomes of rodents and primates. Dot blot hybridization assays revealed that such tracts constitute 0.40%, 0.30%, and 0.40%, respectively, of the rat, hamster, and mouse genomes, but only 0.07% and 0.05% of the human and monkey genomes. A plaque hybridization assay of rat and human genomic libraries showed that 37% and 16%, respectively, of the recombinant phages in these libraries contain d(GA) _n ·d(TC) _n tracts. A survey of sequences stored in the GenBank data bank showed that a significant fraction of the stored rodent genes (about 2.0%) contain long d(GA) _n ·d(TC) _n tracts (n> 30) with <10% mismatching. The primate genes contain only shorter tracts (n<15) with <10% mismatching. In addition, the rodent and the primate genes contain tracts with larger degrees of mismatching. The chicken, which represents an entirely different branch of the evolutionary tree, was found to be as low in d(GA) _n ·d(TC) _n tracts as the primates. It is suggested that a common ancestor of the rodents has acquired the ability to amplify d(GA) _n ·d(TC) _n tracts.     

Antimicrobial susceptibilities of strains of Nocardia brasiliensis isolated from soil of Tucumán

The activity of antimicrobial agents against soil isolates of N. brasiliensis was studied by determination of the minimum inhibitory concentrations (MICs) and disk diffusion technique, according to the National Committee for Clinical Laboratory Standards (NCCLS). The objectives were: (a) to study the patterns of sensitivity among regional strains of N. brasiliensis isolated from natural sources (soil) of different zones of Tucumán province; (b) to correlate these results with those previously obtained with regional strains of N. brasiliensis isolated from human mycetomas, as a contribution in the evaluation of the importance of the natural reservoir area of the potentially pathogen strains. The results obtained by both methods identified strains of N. brasiliensis from soils with similar patterns of susceptibility to the strains N. brasiliensis isolated from human mycetomas. This showed strains sensitive and resistant to antibiotics. The majority of the isolates of N. brasiliensis from soils showed higher susceptibilities to antibiotics than the strains isolated from human mycetomas. Among the antibiotics studied, cefotaxime, ceftriaxone and gentamicin were the most effective against all the regional strains tested, and these results are correlated with those obtained with regional strains that cause human mycetomas. This revised version was published online in June 2006 with corrections to the Cover Date.     

The effects of temperature on the filtration of diluted blood through 3 μm and 5 μm filters

The effect of temperature on the flow of diluted blood [Hct = 0.21], through 5 μm Nuclepore filters, is described by the Arrhenius equation with an energy of activation of 27.7 kJ/mol. Plasma, diluted with PBS, is almost three times less sensitive to temperature, with an energy of activation of 9.8 kJ/mol, while red cells are of intermediate sensitivity, with an energy of activation of 14.7 kJ/mol. The most sensitive elements to changes in temperature are leukocytes, with energies of activation of 31 kJ/mol and 35 kJ/mol for fast-flowing leukocytes (granulocytes and lymphocytes) and slow-flowing leukocytes (monocytes) respectively. Hence, the major determinants of the decline in filterability of blood through micropore filters are the leukocytes. This effect is compounded when blood is kept for 10 minutes or more at 10° C due to activation of granulocytes, which leads to permanent pore blocking when the affected blood is filtered at room temperature. The combination of increased passage time of leukocytes through peripheral areas at abnormally low temperatures and subsequent activation might influence the flow of blood in non-affected tissues. The effect of temperature on the filterability of red blood cells through 3 μm filters is not described by the Arrhenius equation and the deviations are seen as a gradual change of slope rather than a sharp break between two straight lines. The data are consistent with a gradual shift in rate limiting step away from the entry event into pores, which dominates at low temperature but becomes progressively less important at elevated temperatures. The changing parameter is probably the volume of the red cell, which is less important when flow is measured through 5 μm pores.     

Natural occurrence of Nocardia in soil of Tucumán: Physiological characteristics

This is the first study initiated in Argentina to establish the presence of species of Nocardia from soil samples. These samples were gathered in different areas of Tucumán.Thirty three pathogenic strains of Nocardia were isolated by the paraffin bait method. Out of them, 28 were N. brasiliensis, 3 N. asteroides and 2 N. caviae. N. brasiliensis was widely distributed in the soil of the areas tested.It is proved that N. caviae, so rarely found in other regions of the world, occurs in Tucumán.A detailed study of the morphological and physiological characteristics for identification is discussed.     

Validez de la valoración subjetiva global como método de despistaje de desnutrición hospitalaria. Prevalencia de desnutrición en un hospital terciario

IntroductionHospital malnutrition is a highly prevalent problem that affects patient morbidity and mortality resulting in longer hospital stays and increased healthcare costs. Although there is no single nutritional screening method, subjective global assessment (SGA) may be a useful, inexpensive, and easily reproducible tool.MethodsA cross-sectional, observational, randomized study was conducted in 197 patients in a tertiary hospital. SGA, anthropometric data, and biochemical parameters were used to assess the nutritional status of study patients.ResultsFifty percent of subjects were malnourished according to SGA. A higher prevalence of malnutrition was found in medical (53%) as compared to surgical departments (47%). Half the subjects (50%) had malnutrition by SGA, but only 37.8% received nutritional treatment during their hospital stay. Mean hospital stay was longer for patients malnourished (13.5 days) or at risk of malnutrition (12.1 days) as compared to well nourished subjects (6.97 days). SGA significantly correlated (P < .012) with anthropometric and biochemical malnutrition parameters.ConclusionsPrevalence of hospital malnutrition is very high in both medical and surgical departments and is inadequately treated. SGA is a useful tool for screening hospital malnutrition because of its high degree of correlation with anthropometric and biochemical parameters.     

Polymorphism of 2-μm plasmids in industrial strains of Saccharomyces cerevisiae

Restriction fragment length polymorphism (RFLP) analyses of industrial Saccharomyces yeast DNA have identified eight 2-m plasmidsvariants that fall into two distinct types. Type-I plasmids are of unique form, whereas type-II plasmids exist in seven distinct RFLP forms. Only two different 2-m variants were observed in 35 bakers' strains analysed. One variant was the unique type-I whereas the second variant represents an ancestral form of the type-II plasmid. Sixteen of nineteen wine yeasts carried a distinctive type-II plasmid with a homeologous STB repeat whereas ale and lager yeasts had a wide range of type-II variants. Relative to nuclear and mtDNA, 2-m polymorphism is less diverse and not diagnostic for a specific strain. This 2-m DNA polymorphism is a convenient and useful addendum to nuclear and mtDNA RFLP analyses but cannot serve as the sole marker for strain identification. A tentative phylogeny of industrial S. cerevisiae yeasts is suggested with origins in bakers' yeast carrying the ancestral type-II form. Correspondence to: G. H. Rank     

Computational investigation of the geometric structures of [(CN)5PtTl(CN)n]n− (n=0, 1, 2 or 3)

[(CN)₅PtTl(CN)_n]ⁿ⁻ (n=0–3, complexes I–IV) have been studied computationally using quasi-relativistic gradient-corrected density functional theory. Good agreement is obtained with previous EXAFS and Raman data for complexes II–IV, but calculations significantly overestimate the PtTl bond length and underestimate ν(PtTl) for complex I. The addition of co-ordinating water molecules to the thallium atom in complexes I–III has little effect on complexes II and III, but significantly shortens the PtTl bond in complex I, bringing it into excellent agreement with experiment. The bond length shortening is traced to intramolecular hydrogen bonding. The total molecular bonding energies of hydrated I and I′ (in which the axial ligands on the thallium and platinum atoms are interchanged) are found to be very similar to one another, suggesting that complex I might exist as a mixture of isomers in solution.     

A time-dependent mathematical expression of the münch hypothesis of phloem transport

A time-dependent mathematical expression of the Münch, osmotically driven mass flow hypothesis of phloem transport is presented. The dependent variables include concentration of solutes, pressure, velocity of phloem sap, osmotic flux of water, and concentration dependent unloading of solutes. The model meets conservation requirements during all iterations, and responds realistically to changes in independent variables. Given the same set of independent variables the time-dependent model converges to the same values as the closed-form steady-state model of Goeschl et al. (1976) regardless of the initial conditions.     

Paleolimnology of the Petén Lake district,Guatemala

The long-term impact of Maya culture on a lowland tropical watershed is assessed, using data from a 9.2 m sediment core taken from deep water (28 m) in Lake Quexil. Human population growth, estimated by the 1980 archaeological survey, is associated with a shift in the composition of the sediment to a dominance by inorganic material, the Maya clay formation, beginning ca. 3500 B.P. Increasing settlement densities are correlated with accelerated influxes of phosphorus, carbonates, and siliceous sediment. However, chemical data do not track short-term population fluctuations closely. Because much of the sediment is delivered as colluvium, and not by running water, there is a lag between terrestrial disturbance and impact on the aquatic system. As an indication of this lag, contemporary high sedimentation rates are a residual of Maya activity that virtually ceased some 300–400 years B.P. Comparison of the deep-water core with a shallow-water (7 m) section, based on palynological correlation, reveals only minor differences in proximate chemical composition. Chemical influxes are much higher at the deep-water site, however, as a consequence of sediment focusing in this hyperconical basin. Chemical analyses of soil samples from 21 test pits in the Quexil basin support the principal conclusion that bulk soil movement was the mode of nutrient transfer to the lake, following forest clearance by the Maya.     

Signature of n→π* interactions in α-helices

The oxygen of a peptide bond has two lone pairs of electrons. One of these lone pairs is poised to interact with the electron-deficient carbon of the subsequent peptide bond in the chain. Any partial covalency that results from this n→π* interaction should induce pyramidalization of the carbon (C'(i)) toward the oxygen (O(i-1)). We searched for such pyramidalization in 14 peptides that contain both α- and β-amino acid residues and that assume a helical structure. We found that the α-amino acid residues, which adopt the main chain dihedral angles of an α-helix, display dramatic pyramidalization but the β-amino acid residues do not. Thus, we conclude that O(i-1) and C'(i) are linked by a partial covalent bond in α-helices. This finding has important ramifications for the folding and conformational stability of α-helices in isolation and in proteins.     

Asociación de polimorfismos en el gen FTO con la obesidad mórbida en la población extremeña

ObjectiveTo select individuals whose morbid obesity can be attributed mainly to their individual genetic profile. After excluding patients with potential monogenic syndromes or diseases associated with obesity, we evaluated the association of the single nucleotide polymorphisms (SNPs) rs1861868 and rs9939609 of the fat-mass and obesity-associated FTO gene with an inherited predisposition to morbid obesity.Patients and methodsWe evaluated 270 patients with morbid obesity and onset before the age of 14 years and selected 194 due to their phenotypes and family history; 289 control individuals were included. The rs1861868 and rs9939609 variants, located in the FTO gene, were genotyped. Genotype and haplotype frequencies were compared between cases and controls.ResultsThe A allele of rs9939609 was associated with severe obesity starting in childhood among the Spanish population. The rs1861868 G/rs9939609 A haplotype of the FTO gene was also significantly associated with severe obesity in our population, with an odds ratio of 3.03 (95% confidence interval, 1.74–5.27).ConclusionAnalysis of the genetic basis of obesity requires rigorous selection of cases. In this study, the association of the rs9939609 SNP with obesity widely described in distinct populations was confirmed among overweight Spanish children. Genotyping rs1861868 allowed us to identify the first risk haplotype in the FTO gene, which is located in the adjacent haplotype block containing rs9939609. In-depth study of the variability of the FTO gene is essential to define its deleterious capacity.     

Infección múltiple fúngica en un paciente diabético

BackgroundMixed fungal infections although undervalued, are more common than mentioned in the scientific literature. These infections have a poor prognosis for the patient.ObjectivesWe present an unusual case of a 61-year-old diabetic male who had a rhino-orbito-sinusal zygomycosis in 2001. After surgical debridement of the infected parts, along with antifungal therapy with liposomal amphotericin B, the patient started improving. Several years later the patient was hospitalized due to a similar problem and was diagnosed of rhino-orbito-cerebral zygomycosis.MethodsIn both episodes, a histopathological examination and cultures were performed on the sinus lesions. Tissue sections were stained with haematoxylin and eosin, Giemsa, periodic acid-Schiff (PAS) and Grocott's methenamine silver, and cultures specific for fungi were performed.ResultsThe histopathology studies revealed the presence of bacteria, actinomyces and a mixed infection by at least four different fungi, all of them well differentiated by their morphology. Despite the rapid diagnosis the patient died due to spreading to the central nervous system.ConclusionsMixed infections by fungi are rare, but due to the high incidence of immunodeficiencies they could occur more often than reported. We would like to alert on the possibility of acquired mixed infection by fungi which have shown to be high aggressive and have a worse prognostic in patients with underlying diseases.