Beneficial effect of angiotensin-converting enzyme inhibitor on dilated cardiomyopathy induced by autoimmune mechanism against beta1-adrenoceptor

We have shown that a peptide corresponding to the sequence of the second extracellular loop of the human beta1-adrenoceptor (beta1-peptide) was able to induce an autoimmune cardiomyopathy in rabbits. In this study, we examined the effect of angiotensin-converting enzyme inhibitor (ACEI) on beta1-peptide-induced cardiomyopathy. Rabbits were divided into four groups: (1) control group (n= 6) receiving saline injection; (2) beta1-peptide group (n = 8) immunized with beta1-peptide; (3) ACEI group (n = 6), lisinopril (3 mg/day) given orally and receiving saline injection; and (4) ACEI + beta1-peptide group (n = 7), lisinopril (3 mg/day) given orally and immunized with beta1-peptide. Our results showed that, after 1 year, all rabbits in the beta1-peptide group had an increase in heart weight, wall thinning and dilatations of both ventricles as compared with rabbits in the ACEI + beta1-peptide group that had normal heart weight and shape. All rabbits in the beta1-peptide group exhibited multifocal degeneration and necrosis of myocardial cells with moderate infiltration of inflammatory cells. In the ACEI + beta1-peptide group, three rabbits showed focal degeneration and necrosis of myocardial cells accompanied by mononuclear cells. The lesions in this group were apparently less marked than those in the beta1-peptide group. In conclusion, ACEI protects the myocardium from injury induced by an autoimmune mechanism against beta1-adrenoceptor.     

Determination of the minimal concentrations of contact activation factors in deficient substrate plasmas required to assess accurately factor XII, factor XI, factor IX, and high molecular weight kininogen

Using combined deficient plasmas prepared by passage of a deficient plasma over an anti-factor XI-monoclonal antibody column, we have determined the threshold concentrations of each coagulation factor of contact phase in factor-deficient substrate plasmas required to determine accurately the functional activities of factor XII, factor XI, factor IX and high molecular weight kininogen (HMWK). In order to reliably quantitate factor XI and factor IX activity levels, at least 20% factor XII and 20% factor XI, respectively, were required in the deficient substrate plasmas. In the assessment of factor XII activity, approximately 40% factor XI was required in the factor XII-deficient substrate plasma. On the other hand, only 11-12% factor XI or HMWK was required in the deficient substrate plasmas in the assessment of these two clotting factors. Our data emphasize that deficiencies of other clotting factors may reduce the apparent activity of the clotting factor in question if their concentration is rate-limiting in the clotting assay.     

Peritubular capillaritis in early renal allograft is associated with the development of chronic rejection and chronic allograft nephropathy

Abstract:  Peritubular capillaritis (PTCitis) has been recognized as one form of acute/active allograft rejection, and its relation to humoral immunity has been suggested. However, its mechanisms remain to be fully clarified, and there are no criteria for evaluating the extent of PTCitis in a biopsied allograft. In this study, we first evaluated the extent of PTCitis in early allografts in patients presenting with acute cellular rejection (ACR) and antibody-mediated rejection (AbAR). We also included patients who showed no evidence of ACR and/or AbAR. Next, we investigated whether or not PTCitis persisted and if peritubular capillary basement membrane (PTCBM) thickening was present in their follow-up biopsy specimens. We adopted the scoring system of PTCitis, which was presented at the Seventh Banff Conference on Allograft Pathology in 2003. In total, 53 patients were included in this study. At first biopsy, 17 showed ACR, eight showed AbAR, 16 showed mild PTCitis only, and 14 were without significant pathologic changes. The PTC score was the highest in the AbAR group, and in some patients the score gradually increased during the follow-up period. Similar changes were also observed in the group with mild PTCitis only. In late allografts, half of the patients with AbAR developed chronic rejection (CR), and the PTCBM score was the highest in that group. Surprisingly, CR was present in more than 30% of patients without ACR and/or AbAR but mild PTCitis only. In the control group, only a few showed CR and/or chronic allograft nephropathy (CAN). In conclusion, it became clear that we should carefully monitor for mild PTCitis in early allografts. In addition, our data also proved the usefulness of the PTC score and PTCBM score.     

Stability of brain natriuretic peptide (BNP) in human blood samples.

Stability of immunoreactivity of human brain natriuretic peptide (BNP) in blood samples was investigated. After storage of the whole blood samples in the blood collecting tubes made of glass or polyethylene terephthalate (PET), residual immunoreactivity of BNP in the plasma was measured by sandwich radioimmunoassay for human BNP. BNP in the blood samples collected in the PET tubes were kept more stable than that in the glass tubes. The results suggested that commercially available PET tubes would enable more accurate BNP values and this would also help to simplify the sample preparation.     

Two cases of ANCA-associated vasculitis in post-transplant kidney: relapse and de novo

Abstract:  Two cases of anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis (ANCA-V) occurred in the transplanted kidney were reported. Case 1 was a 57 yr-old female whose original disease was MPO-ANCA-V. A relapse of necrotizing crescentic glomerulonephritis occurred one year after transplantation with positive serum reaction for MPO-ANCA. In spite of several immunosuppressive treatments, the disease progressed and she returned to hemodialysis treatment three yr and seven months after transplantation. Case 2 was a 34 yr-old female whose original disease was IgA nephropathy. She had a stable clinical condition during 13 yr after transplantation; however, de novo onset of necrotizing crescentic glomerulonephritis occurred at 14 yr 10 months after transplantation with positive serum reaction for MPO-ANCA. She returned to hemodialysis treatment five yr after the onset of ANCA-V. Urinary abnormities such as microhematuria and proteinuria were useful diagnostic findings but the titers of serum MPO-ANCA were relatively low in both patients. Concerning the treatment, steroid pulse therapy was effective in some extents but the disease progressed to graft failure in both cases. ANCA-V is a severe glomerulonephritis which can occur in kidney allograft in the manner of relapse and de novo . Detection of urinary abnormalities and positive serum ANCA combined with histological confirmation of necrotizing crescentic glomerulonephritis and/or vasculitis is required for early diagnosis and effective treatment of ANCA-V in renal transplant patients.     

Role of the cyclooxygenase 2-thromboxane pathway in 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced decrease in mesencephalic vein blood flow in the zebrafish embryo

Previously, we reported that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) evoked developmental toxicity required activation of aryl hydrocarbon receptor type 2 (AHR2), using zebrafish embryos. However, the downstream molecular targets of AHR2 activation are largely unknown and are the focus of the present investigation. TCDD induces cyclooxygenase 2 (COX2), a rate-limiting enzyme for prostaglandin synthesis in certain cells. In the present study, we investigated the role of the COX2-thromboxane pathway in causing a specific endpoint of TCDD developmental toxicity in the zebrafish embryo, namely, a decrease in regional blood flow in the dorsal midbrain. It was found that the TCDD-induced reduction in mesencephalic vein blood flow was markedly inhibited by selective COX2 inhibitors, NS-398 and SC-236, and by a general COX inhibitor, indomethacin, but not by a selective COX1 inhibitor, SC-560. Gene knock-down of COX2 by two different types of morpholino antisense oligonucleotides, but not by their negative homologs, also protected the zebrafish embryos from mesencephalic vein circulation failure caused by TCDD. This inhibitory effect of TCDD on regional blood flow in the dorsal midbrain was also blocked by selective antagonists of the thromboxane receptor (TP). Treatment of control zebrafish embryos with a TP agonist also caused a reduction in mesencephalic vein blood flow and it too was blocked by a TP antagonist, without any effect on trunk circulation. Finally, gene knock-down of thromboxane A synthase 1 (TBXS) with morpholinos but not by the morpholinos' negative homologs provided significant protection against TCDD-induced mesencephalic circulation failure. Taken together, these results point to a role of the prostanoid synthesis pathway via COX2-TBXS-TP in the local circulation failure induced by TCDD in the dorsal midbrain of the zebrafish embryo.     

Development and assessment of an automatic quantitative cerebral vascular reserve estimation tool for use with triple-injection 99mTc-ECD SPECT

In nuclear medicine, cerebral vascular reserve(CVR) is evaluated using technetium-99m ethyl cysteinate dimer [99mTc-ECD] and acetazolamide(ACZ). We developed a protocol involving the intravenous injection of 99mTc-ECD in three divided doses(TIE method), and have found that the cerebrovascular response to ACZ depended on time after ACZ administration. However, it was difficult to obtain high-precision quantitative SPECT images by the conventional method because of complicated image processing and image degradation accompanying image subtraction. We recently developed software known as the Automatic Quantitative CVR Estimation Tool(hereinafter referred to as Triple AQCEL), which, after the input of simple parameters, enables us to carry out automatic reconstruction of quantitative SPECT images without image degradation due to subtraction. Triple AQCEL was determined to reduce image degradation caused by subtraction and to provide valid quantitative data. Because Triple AQCEL does not require manual determination of ROI or image selection for the reconstruction of quantitative SPECT images, reproducibility of regional cerebral blood flow by 3DSRT is ensured. Since all analyses in evaluation by the TIE method are automated and the operator plays no part in them, with the resulting increase of throughput, this software will contribute to improved reproducibility of regional cerebral blood flow data, and will be useful in clinical pathophysiological assessment both preoperatively and during postoperative follow-up.