Effect of Helicobacter pylori-induced cyclooxygenase-2 on gastric epithelial cell kinetics: implication for gastric carcinogenesis

Background. Cyclooxygenase (COX)‐2 induced by Helicobacter pylori is thought to enhance gastric carcinogenesis by affecting the maintenance of epithelial homeostasis. Materials and Methods. Gastric biopsies from 160 subjects, 97 with nonulcer dyspepsia (47 H. pylori negative, 50 H. pylori positive) and 63 with gastric cancer were examined immunohistochemically for COX‐2 expression, cell proliferation and apoptotic indices. Results. COX‐2 expression in corpus was significantly higher in H. pylori positive than in negative non‐ulcer dyspepsia (NUD) (p < .05). Regardless of site, gastric cancer subjects had higher COX‐2 expression in both antrum and corpus compared with H. pylori negative and positive NUD (p < .005). Proliferation was higher in cancer and H. pylori positive than in negative NUD (p < .0001). Moreover, cancer had enhanced proliferation than H. pylori positive NUD in corpus greater (p = .0454) and antrum lesser (p = .0215) curvatures. Apoptosis was higher in H. pylori positive than in negative NUD (p < .05). However, both had a higher index than the cancer subjects (p < .0001). Apoptosis : proliferation ratio was higher in corpus of H. pylori negative than in positive NUD in greater (p = .0122) and lesser (p = .0009) curvatures. However, both had a higher A:P ratio than cancer cases (p = .0001). A negative correlation between COX‐2 expression and A:P ratio was found in corpus greater (r = –.176, p= .0437) and lesser (r = –.188, p= .0312) curvatures. Conclusion. The expression of COX‐2 is associated with disruption in gastric epithelial kinetics and hence may play a role in gastric carcinogenesis.     

CD8 T cells are essential in the development of respiratory syncytial virus-induced lung eosinophilia and airway hyperresponsiveness

Viral respiratory infections can cause bronchial hyperresponsiveness and exacerbate asthma. In mice, respiratory syncytial virus (RSV) infection results in airway hyperresponsiveness (AHR) and eosinophil influx into the airways. The immune cell requirements for these responses to RSV infection are not well defined. To delineate the role of CD8 T cells in the development of RSV-induced AHR and lung eosinophilia, we tested the ability of mice depleted of CD8 T cells to develop these symptoms of RSV infection. BALB/c mice were depleted of CD8 T cells using anti-CD8 Ab treatment before intranasal administration of infectious RSV. Six days postinfection, airway responsiveness to inhaled methacholine was assessed by barometric body plethysmography, and numbers of lung eosinophils and levels of IFN-gamma, IL-4, and IL-5 in bronchoalveolar lavage fluid were monitored. RSV infection resulted in airway eosinophilia and AHR in control mice, but not in CD8-depleted animals. Further, whereas RSV-infected mice secreted increased amounts of IL-5 into the airways as compared with noninfected controls, no IL-5 was detectable in both bronchoalveolar lavage fluid and culture supernatants from CD8-depleted animals. Treatment of CD8-depleted mice with IL-5 fully restored both lung eosinophilia and AHR. We conclude that CD8 T cells are essential for the influx of eosinophils into the lung and the development of AHR in response to RSV infection.     

The role of Pro-239 in the catalysis and heat stability of subtilisin E

Site-directed mutagenesis was employed to analyze the role of an alpha-helix containing catalytic Ser-221 of subtilisin E. Pro-239 located at the carboxy-terminal end of the alpha-helix was first replaced with Gly to examine the role of Pro-239 in the catalysis and stability of subtilisin E. The mutation was found to decrease both the catalytic rate (kcat) and the heat stability. This result strongly suggests that Pro-239 plays an important role in the maintenance of the alpha-helix, affecting the functioning of the active site. Various amino acid substitutions at position 239 were attempted to obtain the active subtilisins from Gly-239 subtilisin. Lys- and Arg-substitutions were found to result in more active and stable subtilisins than the Gly-239 subtilisin. In particular, the Arg-239 mutant showed enhanced heat stability compared with the wild type. These results demonstrate the important role of the alpha-helix containing catalytic Ser-221 in the catalysis as well as in the heat stability of subtilisin.     

Evident diversity of codon usage patterns of human genes with respect to chromosome banding patterns and chromosome numbers; relation between nucleotide sequence data and cytogenetic data.

The sequences of the human genome compiled in DNA databases are now about 10 megabase pairs (Mb), and thus the size of the sequences is several times the average size of chromosome bands at high resolution. By surveying this large quantity of data, it may be possible to clarify the global characteristics of the human genome, that is, correlation of gene sequence data (kb-level) to cytogenetic data (Mb-level). By extensively searching the GenBank database, we calculated codon usages in about 2000 human sequences. The highest G + C percentage at the third codon position was 97%, and that of about 250 sequences was 80% or more. The lowest G + C% was 27%, and that in about 150 sequences was 40% or less. A major portion of the GC-rich genes was found to be on special subsets of R-bands (T-bands and/or terminal R-bands). AT-rich genes, however, were mainly on G-bands or non-T-type internal R-bands. Average G + C% at the third position for individual chromosomes differed among chromosomes, and were related to T-band density, quinacrine dullness, and mitotic chiasmata density in the respective chromosomes.     

Preliminary study of a physiological evaluation method on attentiveness concentration during mental arithmetic; correlation between task performance and physiological indices

It is important that task performance is physiologically evaluated in consideration of arousal level. But there are relatively few preceding studies. In this study, the relationship between task performance and physiological indices was studied with regard to attentiveness concentration. The subjects were eight healthy college students. They performed calculations and a visual display terminal (VDT) task. Electroencephalogram (EEG) frequency component, alpha attenuation coefficient (AAC), skin potential level (SPL), blood flow of the finger tip skin (BF), and visual analog scale (VAS), were measured. In order to quantify task performance, correlations between the task performance and physiological indices during the mental task were analyzed. The results suggest that AAC correlates with the error rate in calculation. BF also correlates with the error rate in calculation, while the calculation speed correlates with SPL. It can be inferred that the task speed and error rate are supposed to be related to the different physiological background.     

Transfer of the enhancing effect of respiratory syncytial virus infection on subsequent allergic airway sensitization by T lymphocytes.

In mice, respiratory syncytial virus (RSV) infection enhances allergic airway sensitization, resulting in lung eosinophilia and in airway hyperresponsiveness (AHR). The mechanisms by which RSV contributes to development of asthma and its effects on allergic airway sensitization in mice are not known. We tested whether these consequences of RSV infection can be adoptively transferred by T cells and whether depletion of T cell subsets prevents the effects of RSV infection on subsequent airway sensitization. Mononuclear cells, T lymphocytes, or CD4 or CD8 T cells from peribronchial lymph nodes (PBLN) of RSV-infected mice were transferred into naive BALB/c mice which were then exposed to OVA via the airways. Additionally, RSV-infected mice were depleted of CD4 or CD8 T cells following acute RSV infection but prior to airway sensitization. Following sensitization, airway responsiveness to inhaled methacholine, numbers of lung eosinophils, and levels of IFN-gamma, IL-4, and IL-5 in PBLN cell cultures were monitored. Transfer of T cells from RSV-infected mice resulted in increased eosinophil influx into the lungs, increased IL-5 production, and development of AHR following airway sensitization to allergen. Transfer of CD8 but not CD4 T cells from the PBLN of RSV-infected mice also resulted in AHR following 10 days of OVA exposure. Further, depletion of CD8 T cells prevented these consequences of RSV infection while CD4 T cell depletion reduced them. We conclude that T cells, in particular CD8 T cells, are critical in mediating RSV-induced development of lung eosinophilia and AHR following allergic airway sensitization.     

Cluster of fibronectin type III repeats found in the human major histocompatibility complex class III region shows the highest homology with the repeats in an extracellular matrix protein, tenascin.

Walking and sequencing a genome portion centromeric of CYP21B in the human MHC class III region disclosed a cluster of fibronectin type III repeats in an approximately 50-kb DNA segment. Fibronectin type III repeats are known to consist of ca. 90 amino acid residues and exist in a wide range of protein species. Homology searches in protein databases showed that the repeats found had the highest homology with the repeats of human tenascin, an extracellular matrix protein. One cDNA sequence located immediately centromeric of CYP21B, the 3' portion of which is transcribed by the opposite strand of CYP21B, was found also to have six type III repeats followed by a fibrinogen domain. Pairwise homology comparison of these repeats in the MHC locus with those of human tenascin showed a general parallelism in their gene organization, indicating that the newly found repeats are elements of certain tenascin-like genea.