Identification of the acidic degradation products of hexenuronic acid and characterisation of hexenuronic acid-substituted xylooligosaccharides by NMR spectroscopy

A 4-O-methylglucuronoxylan was converted into a hexenuronoxylan at high temperature and alkalinity similar to the conditions used during kraft pulping. The hexenuronoxylan was hydrolysed with enzymes, and acidic xylooligosaccharides were separated from the hydrolysate by anion-exchange and size-exclusion chromatography. The primary structure of the two main hexenuronic acid-substituted xylooligosaccharides (a tetramer and a pentamer) was determined by two-dimensional ¹H and ¹³C NMR spectroscopy. The 4-deoxy-hexenutronic acid is not stable under the acid hydrolysis step of conventional carbohydrate analysis. Here, we have identified the acidic degradation products of 4-deoxy-hexenuronic acid by NMR spectroscopy. Two degradation pathways were observed, both resulting in a furan derivative.     

Histochemical observations on the role of ferric chloride in the high-iron diamine technique for localizing sulphated mucosubstances

Synopsis The binding of ferric ions to tissue sites, other than those containing sulphated mucosubstances, in sections subjected to the high iron diamine technique was followed by the Prussian blue reaction in order to throw new light on the role of ferric chloride in the high-iron diamine dye bath. From experiments involving enzyme digestions in particular, evidence was obtained that ferric ions bind to ribonucleic acid (in chief cells of the rabbit stomach), deoxyribonucleic acid (in nuclear chromatin granules), and, under certain conditions, to sialic acid residues (e.g. in mucous acini of the mouse sublingual gland) and protein carboxyl groups (in smooth muscle cells) as well.With a few exceptions, the binding of ferric ions to nucleic acids was not affected by changes in the ferric chloride concentration, pH or magnesium chloride concentration in the dye bath; the bond thus formed was very stable. It is possible that the initial linkage is not an electrostatic one. Under all the conditions investigated, it was found that the diamine complexes have a greater affinity for sulphated mucosubstances than ferric ions, but ferric chloride, by lowering the pH of the dye bath, excludes the carboxyl groups from reacting with the positively-charged diamine polymer molecules. It is possible that a high concentration of ferric ions in the high-iron diamine dye bath inhibits the binding of some diamine complexes to nuclei and gastric chief cells, i.e. sites where no sulphated mucosaccharides are present, although this conclusion needs further substantiation.     

Structural Proteins and Subunits of Rubella Virus

Polyacrylamide gel electrophoresis of purified rubella virus revealed two distinct structural proteins VP1 and VP3, which had molecular weights of 62,500 and 35,000, respectively. In addition, a broad variable peak, designated VP2, with a molecular weight of about 47,500, was seen. Sucrose gradient analysis of virus disrupted by neutral detergents separated a labile 150S ribonucleoprotein, containing 40S ribonucleic acid and VP3, from the envelope fraction containing VP1 and VP2. VP1 and particularly VP2 were labeled with glucosamine and are thus glycoproteins. Labeling the polypeptides with different amino acids indicated that VP3, the "core" protein, is relatively rich in arginine but not in lysine. The size of the two main polypeptides, VP1 and VP3, corresponds to those of group A arboviruses.     

RGD-dependent entry of coxsackievirus A9 into host cells and its bypass after cleavage of VP1 protein by intestinal proteases.

The recently reported nucleotide sequence of coxsackievirus A9 (CAV-9) showed that unlike other enteroviruses, CAV-9 has an insertion of about 17 amino acids at the C-terminal end of VP1 (K. H. Chang, P. Auvinen, T. Hyypi?, and G. Stanway, J. Gen. Virol. 70:3269-3280, 1989). This sequence includes the RGD (arginine-glycine-aspartic acid) motif which is known to be important in certain protein-protein interactions. We studied the inhibitory effect of RGD-containing peptides in the attachment of CAV-9 to African green monkey kidney cells. A peptide corresponding to the RRGDM sequence derived from the inserted segment of CAV-9 was found to block virus attachment effectively, and the inhibition was dose dependent. Substitution of glutamic acid for the homologous aspartic acid completely abolished the inhibitory effect, indicating great specificity of the action. During replication in the gut, all enteroviruses are exposed to host proteolytic enzymes. Exposure of CAV-9 to purified trypsin or human intestinal fluid resulted in selective cleavage of the VP1 capsid protein. Intact and trypsin-cleaved VP1 proteins gave identical N-terminal sequences, indicating that cleavage of VP1 takes place near the C terminus. Attachment of proteolytically cleaved infectious CAV-9 to green monkey kidney cells was not prevented by RGD-containing peptides, indicating that cleaved CAV-9 is able to bypass RGD-dependent entry. The altered receptor specificity of proteolytically cleaved viruses may have important consequences in the pathogenesis of enteric infections.     

Resting energy expenditure in young adults born preterm--the Helsinki study of very low birth weight adults

Background

Adults born preterm with very low birth weight (VLBW; <1500g) have higher levels of cardiovascular and metabolic risk factors than their counterparts born at term. Resting energy expenditure (REE) could be one factor contributing to, or protecting from, these risks. We studied the effects of premature birth with VLBW on REE.

Methodology/Principal Findings

We used indirect calorimetry to measure REE and dual x-ray absorptiometry (DXA) to measure lean body mass (LBM) in 116 VLBW and in 118 term-born control individuals (mean age: 22.5 years, SD 2.2) participating in a cohort study. Compared with controls VLBW adults had 6.3% lower REE (95% CI 3.2, 9.3) adjusted for age and sex, but 6.1% higher REE/LBM ratio (95% CI 3.4, 8.6). These differences remained similar when further adjusted for parental education, daily smoking, body fat percentage and self-reported leisure time exercise intensity, duration and frequency.

Conclusions/Significance

Adults born prematurely with very low birth weight have higher resting energy expenditure per unit lean body mass than their peers born at term. This is not explained by differences in childhood socio-economic status, current fat percentage, smoking or leisure time physical activity. Presence of metabolically more active tissue could protect people with very low birth weight from obesity and subsequent risk of chronic disease.     

Plasma and Cerebrospinal Fluid Amino Acids in Epileptic Patients

Altered plasma and cerebrospinal fluid amino acid levels may be associated with human epilepsy. We studied three groups of patients, those with a generalized epileptic syndrome, juvenile myoclonic epilepsy, patients with refractory localization-related epilepsies, and patients with acute seizures (within 24 h). Plasma levels of amino acids were studied in all patient groups, as were those in the cerebrospinal fluid (CSF) of patients with acute seizures. After acute seizures, the amino acid changes in the CSF were limited to a reduction in the level of taurine, whereas the levels of most amino acids in plasma were decreased. On the other hand, levels of the excitatory amino acids glutamate and aspartate were increased. The most notable finding in the juvenile myoclonic epilepsy patients was an increase in glutamate level in the plasma. Our study supports the conception of an altered metabolism of glutamate in generalized epilepsies.     

Strain-Specific Identification of Probiotic Lactobacillus rhamnosus with Randomly Amplified Polymorphic DNA-Derived PCR Primers

In the present work, strain-specific PCR primers for Lactobacillus rhamnosus Lc 1/3 are described. The randomly amplified polymorphic DNA (RAPD) technique was used to produce potential strain-specific markers. They were screened for specificity by hybridization with DNA from 11 L. rhamnosus strains. A 613-bp RAPD marker found to be strain-specific was sequenced, and a primer pair specific to L. rhamnosus Lc 1/3 was constructed based on the sequence. The primer pair was tested with 11 Lactobacillus species and 11 L. rhamnosus strains and was found to be strain specific. The nucleotide sequence of the specific RAPD marker was found to contain part of a protein encoding region which showed significant similarity to several transposases for insertion sequence elements of various bacteria, including other lactic acid bacterium species.     

Size-dependent over-winter mortality of young-of-the-year roach, Rutilus rutilus

Over-winter survival of starved and fed young-of-the-year roach from two lakes in central Finland was examined in the laboratory between November 1992 and May 1993. The mortality rate of starving YOY roach (total length 38 ± 2 mm) from small (ca. 0.5 km²), eutrophic Lake Isojärvi was 50%, whilst roach (total length 32 ± 3 mm) from large Lake Päijänne (1106 km²) suffered 42% mortality. Mortality was size-dependent among roach from Lake Isojärvi, smaller individuals being more vulnerable. There was not strict size limit for survival as proposed previously. However, it seems that within populations approximately the same proportion of smallest roach died independent of the absolute lengths of the fish. Mortality of fed roach from both lakes was always < 5%. This good survival indicates indirectly the importance of energy reserves in wintering. Lipid and protein content of fasting roach from lake Isojärvi decreased during the winter. In the group of fasting roach from Lake Päijänne the amount of lipids stored increased between November and March and decreased thereafter. No change in protein content of fasting fish from Lake Päijänne was observed.     

Cold acclimation was partially impaired in boron deficient Norway spruce seedlings

Susceptibility of trees to freezing injury has been suggested to increase in boron (B) deficiency but there is no experimental evidence to support this proposition. In this study, Norway spruce (Picea abies L. Karst.) seedlings were cultivated for two growing seasons in deficient, intermediate and ‘optimal’ B levels. Cold hardening of the seedlings was measured after the second growing season. Freezing tolerance in tips of shoots, needles, stems and roots was determined by controlled freezing tests and electrolyte leakage method, and that of buds, in addition, by differential thermal analysis (DTA). Electrical impedance was used to monitor changes in the apoplastic space during cold acclimation. Root dry weight and shoot height growth were lower in B deficiency. Cold acclimation of buds and stems was reduced by B deficiency. When hardened seedlings were subjected to subzero temperatures for 3 weeks, extracellular electrical resistance of stems became the highest at the lowest B supply which was probably due to decreased desiccation tolerance. As a conclusion, susceptibility to freezing damage may be increased by B deficiency in Norway spruce trees.     

A Second-order Dynamic Model for the Frost Hardiness of Trees

The development of frost hardiness in forest trees is describedby a dynamic model in which the input variables are the prevailingenvironmental conditions and the developmental stage of trees.The assumption of the model is that for each temperature andphotoperiod there is a discrete stationary level of frost hardiness,which is attained if these environmental factors remain constant.The dependence of the stationary level on temperature and photoperiodis assumed to be piece-wise linear and additive. The rate ofacclimation, i.e. frost hardening or dehardening, is describedas a second-order dynamic process with two time constants, thesecond of which changes depending on the stage of the annualdevelopment of the trees. The frost hardiness model was calibratedand tested using experimental data from Douglas fir [Pseudotsugamenziesii var. glauca (Beissn.) Franco] seedlings. The resultssuggest that the second-order model describes the changes infrost hardiness better than the first-order model with onlyone time constant.Copyright 1995, 1999 Academic Press Acclimation, developmental stage, Douglas fir, dynamic model, frost hardiness, photoperiod, Pseudotsuga menziesii, temperature