Human parvovirus b19 infection in patients with coronary atherosclerosis.

BACKGROUND AND AIMS: The identification of possible pathogens for an infectious etiology of atherosclerotic coronary artery disease (CAD) is an expanding field. The present study was undertaken to explore the role of parvovirus B19, a potent infectious agent. METHODS: A total of 565 patients were analyzed (90 patients with CAD, and 475 controls). Serologic analysis for human paravovirus B19 (B19) specific IgM and IgG was carried out in all patients. In addition, tissue specimens were obtained from five patients who received heart transplants. Direct in situ polymerase chain reaction (PCR) and immunocytochemistry were performed in the samples to localize B19 DNA. RESULTS: Enzyme immunoassay showed that the seropositive rate of anti-B19 IgG in patients with CAD was 1.5- to 2.7-fold more frequent than in healthy controls. Clinical characteristics did not affect the prevalence of seropositivity for B19. However, anti-B19 IgM and B19-specific DNA were not detected in healthy or individuals with CAD. Furthermore, nonradioactive in situ PCR found that the majority of B19-specific DNA was located in the endothelial cells of the thickened intima. CONCLUSIONS: Our results first demonstrate a seroepidemiological and histopathological association between chronic B19 infection and CAD, suggesting that B19 infection may have a potential role in the pathogenesis of coronary atherosclerosis.

Activation of telomerase and expression of human telomerase reverse transcriptase in coronary atherosclerosis.

INTRODUCTION: Considerable research on telomerase on human neoplastic and normal long-lived proliferative tissues has emerged. We explored the expression of telomerase in atherosclerotic human epicardial coronary arteries. METHODS: Forty discrete human coronary arterial segments obtained from 19 heart transplant recipients were classified into nonatherosclerotic and atherosclerotic groups based on coronary angiography and histological examination. PCR-ELISA-based telomeric repeat amplification protocol (TRAP), and immunohistochemical analyses were conducted to determine the functional activity and cell-specific expression of telomerase. RESULTS: Seventy percent of atherosclerotic coronary arteries exhibited positive telomerase activity, and the reactivation incidence reached fourfold higher than that of controls (P=.007). The telomerase catalytic protein, human telomerase reverse transcriptase (hTERT), was expressed in 88% of atherosclerotic tissues, a fivefold higher frequency compared with that of the controls. There was also a correlation of hTERT expression with the level of telomerase bioactivity (P=.017) and with the severity of atherosclerotic grade (P<.001). In comparison with the immunostaining of mitotic antigen, Ki-67, we found an association of hTERT expression with actively cycling cells in early lesions but with quiescent cells in late advanced atherosclerotic stages. CONCLUSIONS: The up-regulation of telomerase and its catalytic hTERT protein during stages of atherosclerotic evolution may implicate a role of telomerase in vascular remodeling underlying atherogenesis.

Effects of acute amphetamine administration on AMPA-mediated synaptic activity and expression of AMPA receptor subunit 2 of brain neurons.

We investigated the role of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor (AMPAR) in mechanisms underlying the action of amphetamine (Amph) on brain neurons, for AMPAR has been proposed to participate in psychotic and neurodegenerative disorders. In the cultured rat brain cortical neurons pretreated with 1 microM Amph for 1 h, the accumulation of 45Ca2+ driven by 10 min incubation with 100 microM AMPA was reduced by about 36%. This Amph-induced decrease seems to involve L-type voltage-gated Ca2+ channels, because the AMPA-induced 45Ca2+ uptake was blocked by 70% and 80%, respectively, for untreated and Amph-treated neurons in the presence of nifedipine (1 microM), an antagonist to L-type calcium channels. Whole-cell, patch-clamp recording revealed that AMPA-elicited current amplitude became 26% lower than the control in Amph-treated cultured neurons. Moreover, Amph treatment down-regulated the level of flip-form glutamate receptor 2 (GluR2) mRNA by 27% in cultured neurons but did not change the expression of GluR2 proteins and flop-form mRNA, as detected by quantitative immunocytochemistry and in situ hybridization. In contrast, in postnatal day 4 rats at 1 h after receiving one intraperitoneal injection of 5 mg/kg of Amph, levels of flip GluR2 mRNA were up-regulated by 13% and 18% in neurons of motor cortex layer 5 and pyramidal neurons of hippocampal CA3, respectively. The data suggest that acute action of Amph on brain neurons is possibly associated with decreased AMPA-mediated Ca2+ influx and current amplitude, as well as modified expression of the GluR2 mRNA.

Activation of metabotropic glutamate receptor 5 is associated with effect of amphetamine on brain neurons.

The role of metabotropic glutamate receptor 5 (mGluR5) was explored in mechanisms underlying the action of amphetamine (AMPH). The activity of mGluR5 was monitored by measuring the level of [3H]inositol monophosphates in brain neurons, in response to stimulation of 2-choloro-5-hydroxyphenylglycine (CHPG), a selective agonist of mGluR5. Treatment with 1 microM of AMPH for 1 h or 7 days increased the CHPG (1 mM, 30 min)-evoked phosphoinositide turnover by 46% or 92% and 26% or 84% in cultured cortical and hippocampal neurons, respectively, from that of CHPG-only treated cells. When AMPH was present during CHPG application post-1 h or 7 day AMPH incubation, the rate of phosphoinositide hydrolysis in cortical neurons became 121% or 142% higher than that treated with CHPG only. The postnatal day (P) 21 (juvenile) and P60 (adult) rats received three intraperitoneal injections of 5 mg/kg of AMPH or saline daily for 6 days. They were challenged on the eighth day with one dosage and sacrificed 3 h later. Reversible 3H-glutamate binding detected increases of 22-89% in the binding levels of cortex and hippocampus of both ages following the AMPH injections. Increases of 13-18% in the levels of mGluR5 mRNA were seen in the juvenile pyramidal neurons of hippocampal CA1-4, granular cells of dentate gyrus, and ventral thalamic nuclei, as shown by in situ hybridization. The AMPH-induced altered activity of mGluR5 is probably associated with changes in the expression of the glutamate receptors, including mGluR5. AMPH may modify the sensitivity of mGluR5 or interact with the receptor itself.