Characterization of rat pulmonary monoamine oxidase.

The substrate specificities and kinetics of rat lung monoamine oxidase (MAO) have been studied. Utilizing the irreversible MAO inhibitors, clorgyline and deprenyl, rat lung was shown to possess at least two types of MAO, A and B. Tyramine was a substrate for both forms of the enzyme, whereas 5-hydroxytryptamine (5-HT) was a preferred substrate for the A-form. In contrast to most other tissues, 2-phenylethylamine was not solely a B-type substrate for the rat lung MAO and some metabolism by the A-type was apparent $\text{(}\text{B}\text{A}\text{=}\text{80}\text{20}\text{)}$. Using tyramine as substrate the ratio A/B was shown to be $\text{55}\text{45}$. Rat pulmonary MAO-B was inhibited by deprenyl and the kinetics of MAO-A studied. The Km values for the A-form for tyramine, phenylethylamine and 5-HT were relatively similar and were 270, 244 and 170 μM respectively. Whereas, when the A-form was inhibited by clorgyline, the Km values for the B-form were found to differ considerably: 330, 42 and 850 μM for tyramine, phenylethylamine and 5-HT respectively.     

Major Adverse Cardiovascular Events in Treated Periodontitis: A Population-Based Follow-Up Study from Taiwan

Background

The aim of the present study was to identify the long-term major adverse cardiovascular events (MACE) in treated periodontitis patients in Taiwan.

Methods

From the National Health Insurance Research Database (2001-2010), adult patients (≥ 18 years) with treated periodontitis were identified. Comparison was made between patients with mild form and severe form of treated periodontitis after propensity score matching. The primary end point was the incidence of MACE.

Results

A total of 32,504 adult patients with treated periodontitis were identified between 2001 and 2010. After propensity score matching, 27,146 patients were preserved for comparison, including 13,573 patients with mild form and 13,573 patients with severe form of treated periodontitis. During follow-up, 728 individuals in mild treated periodontitis group and 1,206 individuals in severe treated periodontitis group had at least 1 MACE event. After adjustment for gender, hyperlipidemia, hypertension and diabetes mellitus, severe treated periodontitis was associated with a mildly but significantly increased risk of MACE among older patients > 60 years of age (incidence rate ratio, 1.26; 95% confidence interval, 1.08–1.46). No association was found among younger patients ≤ 60 years of age.

Conclusions

Severe form of treated periodontitis was associated with an increased risk of MACE among older Taiwanese patients, but not among younger Taiwanese patients. We should put more efforts on the improvement of periodontal health to prevent further MACE.     

The Accessory Genome of Pseudomonas aeruginosa

Summary: Pseudomonas aeruginosa strains exhibit significant variability in pathogenicity and ecological flexibility. Such interstrain differences reflect the dynamic nature of the P. aeruginosa genome, which is composed of a relatively invariable “core genome” and a highly variable “accessory genome.” Here we review the major classes of genetic elements comprising the P. aeruginosa accessory genome and highlight emerging themes in the acquisition and functional importance of these elements. Although the precise phenotypes endowed by the majority of the P. aeruginosa accessory genome have yet to be determined, rapid progress is being made, and a clearer understanding of the role of the P. aeruginosa accessory genome in ecology and infection is emerging.     

Molecular and morphological characterization of somatic hybrids between <Emphasis Type="Italic">Solanum tuberosum</Emphasis> L. and <Emphasis Type="Italic">S. etuberosum</Emphasis> Lindl.

Interspecific potato somatic hybrids between Solanum tuberosum L. (di)haploid C-13 and 1 endosperm balance number non-tuberous wild species S. etuberosum Lindl. were produced by protoplasts electrofusion. The objective was to transfer virus resistance from this wild species into the cultivated potatoes. Post-fusion products were cultured in VKM medium followed by regeneration of calli in MS₁₃ K medium at 20°C under a 16-h photoperiod, and regenerants were multiplied on MS medium. Twenty-one somatic hybrids were confirmed by RAPD, SSR and cytoplasm (chloroplast/mitochondria) type analysis possessing species-specific diagnostic bands of corresponding parents. Tetraploid nature of these somatic hybrids was determined through flow cytometry analysis. Somatic hybrids showed intermediate phenotypes (plant, leaves and floral morphology) to their parents in glass-house grown plants. All the somatic hybrids were male-fertile. ELISA assay of somatic hybrids after artificial inoculation of Potato virus Y (PVY) infection reveals high PVY resistance.     

Light-induced transformation of amyloplasts into chloroplasts in potato tubers

The transformation of amyloplast into chloroplasts in potato (Solanum tuberosum L.) tuber tissue can be induced by light. Excised potato tuber discs illuminated with white light of 3000 lux began to synthesize chlorophyll after a lag period of 1 day, and continued to synthesize chlorophyll for 3 weeks. In this paper we present evidence, based on ultracentrifugal sedimentation and immunoprecipitation, that the light-mediated synthesis of Ribulose-1,5-bisphosphate carboxylase began 1 day after illumination with white light. When illuminated the chloroplasts isolated from light-grown potato tuber tissue incorporated [³⁵S]methionine into polypeptides, one of which has been identified as the large subunit of Ribulose-1,5-bisphosphate carboxylase. These chloroplasts are functional as determined by O₂ evolution in the Hill reaction.     

Retina dorsal/ventral patterning by Xenopus TBX3.

Although it is well known that patterning in the retina of vertebrates is essential for retina formation and for the retinotopic projection of axons in the embryo, knowledge of molecular and cellular mechanisms of retina patterning is limited. We have previously identified the Xenopus Tbx3 gene (XTbx3) which is expressed in the dorsal retina but not in the ventral retina in Xenopus embryos [H. Li, C. Tierney, L. Wen, J. Y. Wu, and Y. Rao (1997) Development 124, 603-615; M.-L. He, L. Wen, C. E. Campbell, J. Y. Wu, and Y. Rao (1999) Proc. Natl. Acad. Sci. USA 96, 10212-10217]. Dosage-sensitive phenotypes in humans suggest that the manipulation of the amount and location of its products could be informative for understanding its normal function. Here we report that ectopic expression of Tbx3 by mRNA injection suppressed formation of the ventral retina. Furthermore, Tbx3 injection led to inhibition of molecular markers for the ventral retina including Pax-2 and netrin, indicating that Tbx3 plays an important role in retina dorsal/ventral patterning in vertebrates by inhibition of gene expression for ventral retina specification.     

Differential behaviour of 25-hydroxyvitamin D3 24-hydroxylase and 1-hydroxylase in response to protein synthesis inhibitors and cytochrome P-450 inhibitors

To characterize 25-hydroxyvitamin D3 24-hydroxylase and 25-hydroxyvitamin D3 1-hydroxylase, the activities of the two enzymes were measured in the presence of two types of inhibitors. The effect of protein synthesis inhibitors on 25-hydroxyvitamin D3-stimulated 24-hydroxylase activity in 1-hydroxylating rat kidneys perfused in vitro was tested. Actinomycin D (4 microM) and cycloheximide (10 microM) each abolished 25-hydroxyvitamin D3 24-hydroxylase synthesis when added at the start of perfusion but not when added 4 h later; they did not affect 25-hydroxyvitamin D3 1-hydroxylase activity. The effects of cytochrome P-450 inhibitors on the two enzyme activities were then studied in vivo. Metyrapone and SKF-525A (50 mg/kg body weight) each inhibited 25-hydroxyvitamin D3 24-hydroxylase at 6 and 24 h; in contrast 1-hydroxylase increased and was 5 times the control value at 24 h. Finally, the in vitro effects of six cytochrome P-450 inhibitors at concentrations ranging from 10(-7) to 10(-3) M on enzyme activities in renal mitochondrial preparations were compared. Both enzymes were inhibited by all of the inhibitors, but inhibition of 25-hydroxyvitamin D3 24-hydroxylase was consistently greater than that of 25-hydroxyvitamin D3 1-hydroxylase. These studies demonstrate that 24-hydroxylation and 1-hydroxylation respond differently to protein synthesis inhibitors and to cytochrome P-450 inhibitors. The findings are consistent with the hypothesis that the two enzyme activities are associated with different cytochrome P-450 moieties.