Placental acquisition of maternal specific IgG and Helicobacter pylori colonization in infancy

Background. Colonization with Helicobacter pylori generally occurs in infancy, and the microorganism is often acquired from close family members. Rate of infant colonization may be affected by maternal immune status. Methods. To investigate the potential protective effect of anti‐H. pylori immunoglobulin G (IgG) acquired via the placenta, 65 mothers and their infants were studied from the infant's birth for 1 year. Circulating IgG antibodies were measured by enzyme‐linked immunosorbent assay (ELISA) in cord blood and every 8 weeks. Immunoblotting was performed on sera from infants with significant increases in IgG levels. Rate of infant H. pylori colonization was measured by ¹³C urea breath tests every 4 weeks from the age of 12 weeks. Results. Maternal and infant cord blood specific IgG levels were correlated (R² = .747, p < .001). Infant H. pylori specific IgG fell 5‐fold compared to maternal levels over the first 6 months of life, and rose subsequently in many cases, with the development of novel immunoblot patterns. There were no significant associations between the age at first positive urea breath test and maternal or infant cord specific H. pylori IgG levels. Conclusions. Transplacentally acquired specific IgG antibody does not protect infants from colonization by H. pylori.     

Cytoplasmic location of undermethylated messenger RNA in Novikoff cells.

Novikoff cells in culture were labeled with L-[methyl-3H]methionine and [U-14C]uridine in the presence of (a) TubHcy2, (b) AdoHcy, (c) homocysteine, (d) tubercidin, or (e) without any additions. Only in cultures labeled in the presence of TubHcy were undermethylated cap structures observed to represent a significant portion of [3H]methyl radioactivity. Novikoff cells in culture were then simultaneously labeled with L-[methyl-3H]methionine and [32P]orthophosphate in the presence or absence of TubHcy. Total cytoplasmic, polysomal and monosomal poly(A)-containing RNAs were analyzed. Both monosomal and polysomal mRNA fractions from TubHcy-treated cells contain partially methylated cap structures, suggesting that 2'-O-methylation of the nucleoside adjacent to the pyrophosphate linkage in caps is not required for transport, ribosomal binding or translation. Comparison of nuclear and cytoplasmic cap structures from normal and inhibited cultures indicate that an altered mRNA population is generated in the presence of TubHcy.     

Circular dichroism and NMR studies of metabolically stablealpha-methylpolyamines: spectral comparison with naturally occurring polyamines

Three synthetic polyamine analogs, alpha-methylspermine, and alpha,alpha'-dimethylspermine, were compared with their naturally occurring counterparts, spermidine and spermine, by two different spectral techniques. The interaction of polyamines with oligodeoxynucleotides was measured by circular dichroism in order to monitor the polyamine-induced conversion of right-handed B-DNA to the left-handed Z-form. The methylated analogs were shown to be equally effective as the natural polyamines in inducing the B --> Z transition. The pH dependence of the chemical shift of all carbon atoms in each of the five polyamines was measured by (13)C-NMR spectroscopy. With the exception of expected changes in chemical shift due to the presence of the alpha-methyl substituents, the chemical shifts and pH dependence of all carbon atoms in the three alpha-methyl polyamines were similar to the corresponding naturally occurring polyamines. The combined data indicate that alpha-methyl polyamines have physical properties that are very similar to their natural counterparts. The two metabolically stable polyamine analogs, alpha-methylspermidine and alpha,alpha'-dimethylspermine, are therefore useful surrogates for spermidine and spermine in the study of numerous polyamine-mediated effects in mammalian cell cultures and can be used in such studies without the requirement for coadministration of amine oxidase inhibitors.     

Masking repeats while clustering ESTs

A problem in EST clustering is the presence of repeat sequences. To avoid false matches, repeats have to be masked. This can be a time-consuming process, and it depends on available repeat libraries. We present a fast and effective method that aims to eliminate the problems repeats cause in the process of clustering. Unlike traditional methods, repeats are inferred directly from the EST data, we do not rely on any external library of known repeats. This makes the method especially suitable for analysing the ESTs from organisms without good repeat libraries. We demonstrate that the result is very similar to performing standard repeat masking before clustering.     

Reproductive physiology of female tilapia broodstock

Tilapiine fish have become one of the mostcommercially important groups of cultured freshwaterfish with in excess of 850 000 tonnes producedannually in a range of countries (e.g. Thailand,Taiwan, China, Philippines, Belgium and the USA).However, poor broodstock productivity, owing to lowfecundity and asynchronous spawning cycles, remainsone of the most significant outstanding constraintsupon commercial tilapia production and its futureexpansion. This paper reviews current understanding ofthe reproductive physiology of tilapia with particularemphasis upon those factors deemed critical tosuccessful broodstock management. Special emphasis isplaced upon factors such as fecundity, egg size,spawning periodicity, ovarian development and theexogenous and endogenous regulatory mechanismsinvolved in their control. Mouthbrooding speciesexhibit higher levels of parental care but fecundityis lower and egg size larger than insubstrate-spawning species. Fecundity, the number ofeggs oviposited per spawning act, can be < 350 inmouthbrooders such as Oreochromis mossambicus(Peters) but can exceed 12 000 in substrate-spawnerssuch as Tilapia zillii (Gervais). Eggs producedby mouthbrooders normally exceed 2 mm in diameterwhilst those of substrate spawners average only 1.5 mm.Interspawning intervals of mouthbrooders generallyaverage 30–50 days whether the fish are held in natural orartificial conditions, although substrate-spawningspecies such as Tilapia zillii can re-spawnafter only 6 or 7 days. The dynamics of theasynchronous pattern of ovarian development adopted bytilapiines are complex and result in the ovary beingdominated by late-vitellogenic/maturing oocytes asearly as 8–10 days after spawning. Advancement ofour understanding of these key areas will be essentialif the present constraints on tilapia culture are tobe overcome.     

Serum concentration of total soluble CD44 is elevated in smokers

Soluble CD44 isoforms have been reported as markers of specific malignancies and inflammatory diseases. However, recent reports suggest tobacco smoking may lead to an elevation in the circulating concentration of specific CD44 variants. We, therefore, investigated the effect of smoking status on circulating levels of total sCD44. Total soluble CD44 was measured by enzyme-linked immunosorbent assay in the serum of two age- and gender-matched groups consisting of smokers (n = 19) and non-smokers (n = 20). Smoking status was confirmed by analysis of serum cotinine. The concentration of total sCD44 was found to be significantly elevated in smokers compared with non-smokers (p = 0.025). The observation that total sCD44 concentration is raised in smokers may have relevance to the aetiology of smoking-associated diseases. The effect of smoking on sCD44 concentrations should be considered when assessing the role of sCD44 as a marker of inflammatory disease, cancer, or other disease processes.     

Metabolism of S-adenosylhomocysteine and S-tubercidinylhomocysteine in neuroblastoma cells.

The metabolism of the methylase product inhibitor S-adenosylhomocysteine and its 7-deaza analogue S-tubercidinylhomocysteine has been studied in cultured N-18 neuroblastoma cells. The latter compound, designed to resist metabolic degradation, has been shown to be inert under the same conditions where S-adenosylhomocysteine is rapidly and extensively degraded. The product analyses elucidated by high-performance liquid chromatography indicate that the primary route of S-[8-(14)C]adenosylhomocysteine metabolism in these cells leads to adenosine. This product does not accumulate but is rapidly converted to nucleotides or oxypurines by the action of adenosine kinase and adenosine deaminase, respectively. The presence of the potent adenosine deaminase inhibitor coformycin leads to a pronounced inhibition of oxypurine formation, an increase in nucleotide formation, and a slight accumulation of the primary metabolic products adenosine and adenine.     

Effect of S-adenosyl-1,12-diamino-3-thio-9-azadodecane, a multisubstrate adduct inhibitor of spermine synthase, on polyamine metabolism in mammalian cells

The effects of the potent spermine synthase inhibitor S-adenosyl-1,12-diamino-3-thio-9-azadodecane (AdoDatad) on polyamine biosynthesis have been studied in transformed mouse fibroblasts (SV 3T3 cells) and in mouse leukemia cells (L1210). A dose-dependent decrease in intracellular spermine concentration was observed in both cell lines when grown in the presence of the inhibitor. A major difference in the effects seen in these two cell lines was the cytotoxicity observed in L1210 cells exposed to the inhibitor, which contrasted with little or no effects on growth of SV 3T3 cells treated similarly. Oxidative metabolism of the drug in L1210 cells was suggested by the fact that addition of aminoguanidine, an amine oxidase inhibitor, to the cell cultures ablated the cytotoxic effects of the inhibitor. Complete analysis of intracellular polyamines was carried out, together with analysis of S-adenosylmethionine, decarboxylated S-adenosylmethionine, and the inhibitor. These analyses revealed that, although the inhibitor had a dramatic effect on spermine biosynthesis in the cells studied, a compensatory increase in spermidine biosynthesis was observed. This resulted in no change in total polyamine concentrations in cells treated with inhibitors of either spermine synthase or spermidine synthase (Pegg et al., 1982) alone or in combination. In all cases, the concentration of the aminopropyl donor decarboxylated S-adenosylmethionine increased dramatically, thus allowing for the observed maintenance of total polyamine levels even in the presence of either one or both potent inhibitors of the aminopropyltransferases. Oxidative metabolism of the inhibitor complicates the interpretation of experiments carried out in the absence of amine oxidase inhibitors such as aminoguanidine.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vivo inhibition of Novikoff cytoplasmic messenger RNA methylation by S-tubercidinylhomocysteine.

The analogue S-tubercidinylhomocysteine (STH) has been used to study the methylation of mRNA in vivo. Partial inhibition of cytoplasmic poly(A)-RNA methylation was observed using a level of inhibitor which still permitted cell growth. Characterization of the partially methylated mRNA indicated the presence of cap structures lacking 2'-O-methylnucleosides, m7GpppN', which are normally not found in mammalian mRNA. Inhibition of additional methylated sites in mRNA at the second 2'-O-methynucleoside, and at internal N6-methyladenosine was also observed Methylation of 7-methylguanosine was not affected under the conditions used in these experiments. The methylnucleoside composition of cap structures differed in STH-inhibited and uninhibited cells. These results indicate that a completely methylated cap is not required for transport of mRNA into the cytoplasm. Furthermore, it may now be possible to assess in vivo the sequential nature of mRNA methylation and its potential role in mRNA processing.