Viral level is an indicator of long-term outcome of hepatitis B virus e antigen-negative carriers with persistently normal serum alanine aminotransferase levels

The association between viral level and the long-term outcomes of hepatitis B virus (HBV) carriers who test negative for hepatitis B virus e antigen (HBeAg) but have persistently normal serum alanine aminotransferase levels (PNALT) remains unclear. We examined hepatocarcinogenesis, hepatitis reactivation, predictive factors and the time course of HBV DNA levels during follow-up in 104 HBeAg-negative Japanese carriers with PNALT. During a mean follow-up period of 6.4 ± 3.4 years, 5 patients (4.8%) had hepatocarcinogenesis and 14 (13.5%) had hepatitis reactivation. At 5 and 10 years, the cumulative rates of hepatocarcinogenesis were 2.4% and 9.9%, while those of hepatitis activation were 13.7% and 15.5%, respectively. An HBV DNA level of ≥5 log10  copies/mL was the sole predictor of hepatocarcinogenesis with a univariate analysis. An HBV DNA level of ≥5 log10  copies/mL and an alanine aminotransferase (ALT) level of >20 to ≤40 IU/L were independent predictors of hepatitis reactivation in a Cox model. Because there was no association between hepatocarcinogenesis and ALT activity, the HBV DNA level was considered an essential predictor. In addition, the baseline HBV DNA level was related to the future level and was not subject to wide fluctuations. Our results showed that an HBV DNA level of ≥5 log10  copies/mL predicts subsequent hepatocarcinogenesis and hepatitis reactivation in HBeAg-negative carriers with PNALT. As the baseline HBV DNA level reflects the future level, appropriate clinical management according to the viral level is expected to decrease future risk.

Spontaneous rupture of a left gastroepiploic artery aneurysm in a patient with autosomal-dominant polycystic kidney disease

Autosomal-dominant polycystic kidney disease (ADPKD) has been known to be associated with a variety of vascular diseases. We present a hemodialysis patient with ADPKD who died of a massive intraperitoneal hemorrhage caused by the spontaneous rupture of a left gastroepiploic artery aneurysm. A 64-year-old male was admitted to our hospital with acute upper abdominal pain and hemorrhagic shock. An abdominal angiography showed three aneurysms and the source of hemorrhage was assumed to be the left gastroepiploic artery aneurysm. The patient died of severe metabolic acidosis and disseminated intravascular coagulation (DIC) on the second hospital day. At autopsy, there was massive bleeding into the abdominal cavity, and pathological examination of the left gastroepiploic artery aneurysm revealed a dissecting aneurysm. This is the first case describing a rupture of a gastroepiploic aneurysm in a patient with ADPKD.

Capsular sialic acid limits C5a production on type III group B streptococci

The majority of type III group B streptococcus (GBS) human neonatal infections are caused by a genetically related subgroup called III-3. We have proposed that a bacterial enzyme, C5a-ase, contributes to the pathogenesis of neonatal infections with GBS by rapidly inactivating C5a, a potent pro-inflammatory molecule, but many III-3 strains do not express C5a-ase. The amount of C5a produced in serum following incubation with representative type III strains was quantitated in order to better understand the relationship between C5a production and C5a-ase expression. C5a production following incubation of bacteria with serum depleted of antibody to the bacterial surface was inversely proportional to the sialic acid content of the bacterial capsule, with the more heavily sialylated III-3 strains generating less C5a than the less-virulent, less-sialylated III-2 strains. The amount of C5a produced correlated significantly with C3 deposition on each bacterial strain. Repletion with type-specific antibody caused increased C3b deposition and C5a production through alternative pathway activation, but C5a was functionally inactivated by strains that expressed C5a-ase. The increased virulence of III-3 strains compared to that of III-2 strains results at least partially from the higher sialic acid content of III-3 strains, which inhibits both opsonophagocytic killing and C5a production in the absence of type-specific antibody. We propose that C5a-ase is not necessary for III-3 strains to cause invasive disease because the high sialic acid content of III-3 strains inhibits C5a production.

Class specific influence of dietary Spirulina platensis on antibody production in mice

In the present study, we investigated antibody productions of IgA and other classes, such as IgE and IgG1, in mice as possible evidence of the protective effects of Spirulina toward food allergy and microbial infection. An increase of IgE antibody level in the serum was observed in the mice that were orally immunized with crude shrimp extract as an antigen (Ag group). The antibody level, however, was not further enhanced by treatment with Spirulina extract (SpHW). IgG1 antibody, on the other hand, which was increased by antigen administration, was further enhanced by Spirulina extract. It was noted that the IgA antibody level in the intestinal contents was significantly enhanced by treatment with Spirulina extract concurrently ingested with shrimp antigen, in comparison with that of the Ag group treated with shrimp antigen alone. An enhancement of IgA antibody production by Spirulina extract was also observed in culture supernatant of lymphoid cells, especially in the spleen and mesenteric lymph node from mice treated with Spirulina extract for 4 weeks before antigen stimulation. These results suggest that Spirulina may at least neither induce nor enhance allergic reaction such as food allergy dependent on an IgE antibody, and that when ingested both concurrently with antigen and before antigen stimulation, it may significantly enhance the IgA antibody level to protect against allergic reaction.

Role of C5a-ase in group B streptococcal resistance to opsonophagocytic killing

Type III group B streptococci (GBS) can be subdivided into three subtypes, RDP III-1, III-2, and III-3, on the basis of numerical analysis of HindIII restriction endonuclease digestion patterns (HindIII RDP) with their chromosomal DNAs. In the present study, the effect of C5a on opsonophagocytic killing of a representative strain from each RDP type was investigated by using a novel optical method for determining opsonophagocytic killing, and the effect of C5a-ase treatment of C5a on opsonophagocytic killing was also investigated. Pre-stimulation of polymorphonuclear leukocytes (PMNs) with C5a significantly increased opsonophagocytic killing of all three strains. The increase in killing was abolished by pretreating the C5a with GBS that express C5a-ase, a treatment that also destroyed the chemoattractant activity of the C5a. The kinetics of killing of the RDP III-2 strain differed from those of the other two strains. The survival of the RDP III-2 bacteria continued to decline over the entire 60-min incubation of the opsonophagocytic assay when PMNs were prestimulated with C5a or with C5a that had been inactivated with GBS C5a-ase (dC5a). In contrast, killing of the RDP III-1 and III-3 strains almost ceased after 20 or 60 min when PMNs were prestimulated with dC5a or C5a, respectively. A difference in bacterial killing between the III-2 strain and the III-1 and III-3 strains therefore became increasingly apparent with prolonged incubation time. The percentage of bacteria surviving in the extracellular fluid was approximately the same as the percentages of bacteria surviving in both intracellular and extracellular locations when PMNs were prestimulated with either C5a or dC5a. These data imply that the majority of bacterial killing occurred following phagocytosis and suggest that the enhanced killing of GBS following prestimulation of PMNs with C5a resulted from increased ingestion of the bacteria.

Enhancement of antibody production in mice by dietary Spirulina platensis

Mice fed a Spirulina platensis diet showed increased numbers of splenic antibody-producing cells in the primary immune response to sheep red blood cells (SRBC). However, immunoglobulin G (IgG)-antibody production in the secondary immune response was hardly affected. The percentage of phagocytic cells in peritoneal macrophages from the mice fed S. platensis diet, as well as the proliferation of spleen cells by either concanavalin A (Con A) or phytohemagglutinin (PHA) was significantly increased. Addition of a hot-water extract of S. platensis (SHW) to an in vitro culture of spleen cells markedly increased proliferation of these cells, whereas culture of thymus cells was scarcely affected. The Spirulina extract also significantly enhanced interleukin-1 (IL-1) production from peritoneal macrophages. Addition to the in vitro spleen cell culture of SHW as well as the supernatant of macrophages stimulated with SHW resulted in enhancement of antibody production, that is, an increase of the number of PFC. These results suggest that Spirulina enhances the immune response, particularly the primary response, by stimulating macrophage functions, phagocytosis, and IL-1 production.

Opsonisation of group B streptococci and restriction endonuclease digestion patterns of their chromosomal DNA

Isolates of group B streptococci (GBS) from neonates with early-onset septicaemia are associated with particular restriction endonuclease digestion patterns (RDP types Ia-3 and III-3) of chromosomal DNA. Opsonophagocytosis of serotype Ia and serotype III GBS isolates was studied by the luminol-enhanced phagocytic chemiluminescence (CL) assay. Pools of serum containing GBS type-specific antibody levels equivalent to or just above levels typically found in sera from mothers of infected infants were used. CL intensities induced by GBS isolates of RDP types Ia-2, Ia-3 and III-3 were lower than those of the other RDP types of the same serotype. Opsonophagocytosis was more efficient with serum containing higher concentrations of type-specific antibodies but for RDP type III-3 strains these differences were much less marked than for other RDP types. CL intensity did not correlate with cell surface charge, hydrophobicity or sialic acid content of GBS. Results demonstrate that certain GBS RDP types are more resistant to opsonophagocytosis and suggest that potentially virulent strains with genetic homogeneity may exist.

Restriction endonuclease digest patterns of chromosomal DNA from group B beta-haemolytic streptococci

Scanning densitometry and computer-assisted numerical analysis were used to examine restriction endonuclease digest patterns (RDPs) of chromosomal DNA from 26 infecting strains and 44 vaginal isolates of group B beta-haemolytic streptococci (GBS). At the 95% similarity level, HindIII RDPs of serotype Ia and III strains clustered into four and three RDP types, respectively. Nine of 10 strains from neonates with early-onset septicaemia belonged to two particular RDP types (Ia-3 and III-3). In contrast, serotype III GBS strains from meningitis cases were not characterised by particular RDP types. Associations between RDPs and certain phenotypic characteristics were also found.

Screening of type Ia and Ib Streptococcus agalactiae strains with high sialic acid levels by determination of susceptibility to tetracyclines

The type-specific capsular polysaccharide antigen of Streptococcus agalactiae is recognized to be an antiphagocytic factor in strains having large amounts of it. In the present study, it was indicated that vaginal isolates of types Ia and Ib could be classified into two groups on the basis of both their levels of the sialic acid, which occupies the terminal side chains of the polysaccharide, and their susceptibility to tetracyclines: one group comprised strains with low sialic acid levels (less than 9 micrograms/mg of cell dry weight) as well as with susceptibility to tetracyclines (MIC, less than or equal to 0.5 micrograms/ml), and the other comprised strains with higher sialic acid levels (greater than or equal to 9 micrograms/mg) and resistance to tetracyclines (MIC, greater than or equal to 8 micrograms/ml). A few isolates were found to have low levels of sialic acid and to be resistant to tetracyclines, but no isolates that were both relatively high in sialic acid and susceptible to tetracyclines were ever detected. Among strains of those serotypes, the MICs of tetracyclines were not in proportion to the sialic acid levels and were not affected when the sialic acid levels of each strain were altered by using Todd-Hewitt broth with various concentrations of Na2HPO4 and glucose. It was, therefore, apparent that the correlation of sialic acid levels with susceptibility to tetracyclines was not related directly to the sialic acid content or to the amount of the capsular polysaccharide. Since no plasmid DNAs were detected among representative strains that were tetracycline resistant, it was apparent that at least for the strains tested, resistance was chromosomal gene associated. In strains of S. agalactiae of types of Ia and Ib, the determination of susceptibility to tetracyclines was considered to be useful for screening strains with higher sialic acid levels.

Sialic acid levels and lag time of growth in chemically defined medium containing 200 mM phosphate among strains of various serotypes of Streptococcus agalactiae

The type-specific capsular polysaccharide antigen of Streptococcus agalactiae has in previous experimental studies been considered a significant antiphagocytic factor, whereas the lipoteichoic acid moiety has been suggested to be a factor in adherence to human fetal cell lines. Since epidemiological data concerning these cell constituents in strains from the genital tract are lacking, we attempted serotyping and analysis of these constituents of 100 vaginal isolates. The capsular polysaccharide level was shown to be the amount of sialic acid that occupied the terminal side chains of the polysaccharide. We carried out a study to ascertain whether strains exhibited a lag time of growth in a chemically defined medium containing 200 mM phosphate, which has been suggested to be characteristic of strains with high lipoteichoic acid levels. Strains were classified, on the basis of the results of distribution of sialic acid levels, into three categories: (i) strains with a low sialic acid content of equal to or less than 9 micrograms/mg of cell dry weight; (ii) strains with a moderate sialic acid content of more than 9 but less than 12 micrograms/mg of cell dry weight; and (iii) strains with a high sialic acid content of equal to or more than 12 micrograms/mg of cell dry weight. Strains that belonged to the last category, which, as previous experimental data indicate, are potentially virulent strains, were significantly distributed among isolates of types Ia (P less than 0.001) and III (P less than 0.05). On the other hand, strains exhibiting a lag time of growth in the above-mentioned medium were detected to a significant extent in type III isolates (P <0.02). These results may be related to the epidemiological finding that isolates from neonates with late-onset infection were more frequently serotype Ia and III isolates.