The risk of weekend biopsy: Impact of specimen source and fixation status on HER2 assessment in the treatment of advanced gastric cancer (The HER_WEEKEND study)

Accurate evaluation of human epidermal growth factor receptor type 2 (HER2) expression is crucial for determining chemotherapy regimens in gastric cancer. However, formalin fixation status has been identified as an important factor affecting HER2 assessment reliability. This retrospective cohort study aimed to investigate the correlation between sample collection day (weekday vs. weekend) and source (biopsy vs. surgical specimens) in assessing HER2 expression in patients with unresectable advanced/recurrent gastric cancer. Data were collected from gastric cancer patients who received chemotherapy at a single public hospital in Japan from 2008 to 2021. The analysis included 177 patients (109 men, 68 women) with a median age of 68.0 (21-88) years, and the primary outcome was the HER2 positivity rate. The overall HER2 positivity rate was 18.1%, with higher rates on weekdays (20.0%) compared to weekends (12.8%). Biopsies had higher positivity rates on weekdays (23.9%) but lower rates on weekends (11.1%) than surgical specimens. Significant differences were observed in formalin fixation times between weekdays and weekends for both biopsies and surgical samples. The study findings suggest that longer formalin fixation times on weekends may lead to underestimating HER2 expression, particularly in biopsies. Therefore, it is crucial to be cautious of excessive formalin fixation when collecting samples, especially during weekend biopsies.

BK Polyomavirus-Associated Urothelial Carcinoma of the Bladder with a Background of BK Polyomavirus Nephropathy in a Kidney Transplant Recipient

Renal transplant recipients are at increased risk for the development of a malignant neoplasm. Polyomavirus-associated urothelial carcinoma is a rare tumor that occurs in renal transplant recipients, with approximately 41 cases reported since 2002. It accounts for 27-31% of all post-transplant urothelial carcinomas and develops at an average of 8.5 years after transplantation. Histologically, it shows high-grade urothelial carcinoma (95.1%) with a high frequency of glandular differentiation and micropapillary structures (58.5%) and positive immunohistochemistry for polyomavirus large T antigen, p53 (92.9%), and p16 (100%). We encountered a case of BK polyomavirus (BKPyV)-associated urothelial carcinoma of the bladder diagnosed 54 months after kidney transplantation. Histologically, it was a high-grade urothelial carcinoma with micropapillary features, and immunohistochemically, it was diffusely positive for polyomavirus large T antigen, p16, and p53. BKPyV DNA and mRNA for BKPyV large T antigen have been identified in tissues using real-time polymerase chain reaction. The same sequence of the BKPyV VP1 genome hypervariable region was detected in both transplanted kidney tissue with polyomavirus nephropathy and urothelial carcinoma tissue, suggesting that polyomavirus-associated urothelial carcinoma developed in a background of persistent polyomavirus nephropathy. This case showed typical histological features and was detected and treated at an earlier stage than has been reported. It is important to keep in mind that polyomavirus-associated urothelial carcinoma can develop early after transplantation and might be associated with polyomavirus nephropathy. Because of its rapidly progressive nature, careful follow-up with urine cytology and cystoscopy is necessary. We report this case with a literature review.

Regulation of NETosis and Inflammation by Cyclophilin D in Myeloperoxidase-Positive Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

OBJECTIVE

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is pathologically characterized by focal fibrinoid necrosis, in which ANCA-mediated neutrophil extracellular trap (NET) formation and subsequent endothelial cell necrosis occur. Cyclophilin D (CypD) plays an important role in mediation of cell necrosis and inflammation via the opening of mitochondrial permeability transition pores. This study was undertaken to examine the role of CypD in AAV pathogenesis.

METHODS

We assessed the role and mechanism of CypD in ANCA-stimulated neutrophils in vitro by immunostaining and electron microscopy observation. We performed a comprehensive RNA-sequencing analysis on ANCA-treated murine neutrophils. To investigate the role of CypD in vivo, we assessed disease features in CypD-knockout mice and wild-type mice using 2 different murine AAV models: anti-myeloperoxidase IgG transfer-induced AAV and spontaneous AAV.

RESULTS

In vitro experiments showed that pharmacologic and genetic inhibition of CypD suppressed ANCA-induced NET formation via the suppression of reactive oxygen species and cytochrome c release from the mitochondria. RNA-sequencing analyses in ANCA-treated murine neutrophils revealed the involvement of inflammatory responses, with CypD deficiency reducing ANCA-induced alterations in gene expression. Furthermore, analyses of upstream regulators revealed the relevance of intracellular calcium (CypD activator) and cyclosporin (CypD inhibitor) in ANCA stimulation, indicating that the CypD-dependent opening of mitochondrial permeability transition pores is associated with ANCA-induced neutrophil activation and NETosis. In both AAV mouse models, the genetic deletion of CypD ameliorated crescentic glomerulonephritis via the inhibition of CypD-dependent neutrophil and endothelial necrosis.

CONCLUSION

CypD targeting is a novel and specific therapeutic strategy for AAV via the resolution of necrotizing vasculitis.

A Case of Mesangial Proliferative Nephritis Caused by Slow Cryoglobulin

The patient was a woman in her 60s. She was found to have proteinuria on a health checkup. She did not have any particular subjective symptoms, and no definitive diagnosis was made, despite serological findings indicative of immune abnormalities. A renal biopsy was performed. Light microscopy of renal tissue section revealed mesangial proliferative nephritis. Electron microscopic findings included electron-dense deposits and fibrillar/tubular structures with a diameter of 20-30 nm. These findings suggested the presence of cryoglobulin (CG), but CG was not detected in qualitative or quantitative hematologic tests. Thus, the serum samples were stored at 37°C for a long period of time and then cooled to 4°C. When the obtained precipitates were examined, CG was successfully detected. CG that precipitates only after a long period of time is referred to as slow cryoglobulin (sCG), and sCG is extremely rare. The present case is the first documented case, to our knowledge, of renal disorders caused by sCG. It should be noted that there are some cases in which it takes much time for CG to precipitate. Thus, when CG cannot be detected, it is necessary to spend much time to determine whether CG precipitates.

Soluble Interleukin-2 Receptor Predicts Treatment Outcome in Patients With Autoimmune Tubulointerstitial Nephritis. A Preliminary Study

Background

Autoimmune tubulointerstitial nephritis (TIN) is characterized by immune-mediated tubular injury and requires immunosuppressive therapy. However, diagnosing TIN and assessing therapeutic response are challenging for clinicians due to the lack of useful biomarkers. Pathologically, CD4⁺ T cells infiltrate to renal tubulointerstitium, and soluble interleukin-2 receptor (sIL-2R) has been widely known as a serological marker of activated T cell. Here, we explored the usefulness of serum sIL-2R to predict the treatment outcome in patients with autoimmune TIN.

Methods

Study Design: Single-center retrospective observational study.

Participants

62 patients were diagnosed of TIN from 2005 to April 2018 at Hokkaido University Hospital. Among them, 30 patients were diagnosed with autoimmune TIN and treated with corticosteroids. We analyzed the association between baseline characteristics including sIL-2R and the change of estimated glomerular filtration rate (eGFR) after initiation of corticosteroids.

Results

The serum sIL-2R level in patients with autoimmune TIN was significantly higher than that in chronic kidney disease patients with other causes. Mean eGFR in autoimmune TIN patients treated with corticosteroids increased from 43.3 ± 20.4 mL/min/1.73 m² (baseline) to 50.7 ± 19.9 mL/min/1.73 m² (3 months) (ΔeGFR; 22.8 ± 26.0%). Multivariate analysis revealed that higher sIL-2R (per 100 U/mL, β = 1.102, P < 0.001) level was independently associated with the renal recovery. In ROC analysis, sIL-2R had the best area under the curve value (0.805) and the cutoff point was 1182 U/mL (sensitivity = 0.90, 1-specificity = 0.45).

Conclusions

Our study showed that elevated serum sIL-2R levels might become a potential predictive marker for therapeutic response in autoimmune TIN.

Comparison of administration of single- and triple-course steroid pulse therapy combined with tonsillectomy for immunoglobulin A nephropathy

Immunoglobulin A nephropathy (IgAN) is a form of chronic glomerulonephritis that can cause end-stage renal disease. Recently, tonsillectomy combined with corticosteroid pulse (TSP) has been shown to be effective for achieving clinical remission and favorable renal outcome in patients with IgAN. However, the standard regimen of corticosteroid use in TSP has not been established. Herein, we compared the effect of single- or triple-course steroid pulse therapy combined with tonsillectomy in patients with IgAN.This retrospective, observational cohort study included 122 patients with IgAN enrolled from January 2004 to December 2018 at 2 independent institutions. We divided the patients into 2 groups; single-course (TSP1: n = 70) and triple-course (TSP3: n = 52) of corticosteroid pulse therapy (1 course comprised 3 consecutive days' infusion of 0.5 g methylprednisolone) combined with tonsillectomy. The primary outcome for renal survival was defined as the first occurrence of ≧30% decrease in estimated glomerular filtration rate from baseline. Secondary outcomes included the incidence of clinical remission and recurrence of the disease.Regarding clinical parameters and findings at baseline, there were no significant differences between the 2 groups. The 8-years renal survival in the 2 groups was not significantly different according to Kaplan-Meier curves (TSP1; 82.5% vs TSP3; 69.2%, log-rank test P = .39). The cumulative incidence rates of remission of hematuria (94.4% vs 85.4%, P = .56) and clinical remission (85.0% vs 64.8%, P = .07) were comparable in both groups, while those of proteinuria showed higher rates in TSP1 than TSP3 (88.4% vs 65.4%, P = .02). The cumulative incidence of relapse of hematuria (5.6% vs 2.3%, P = .42) and proteinuria (7.1% vs 3.3%, P = .41) showed no significant differences in the 2 groups. Cox regression analyses showed that the number of courses of corticosteroid pulse therapy was not significantly associated with renal outcome (TSP1 vs TSP3; Hazard ratios 0.69, 95% confidence intervals 0.29-1.64, P = .39).The effect of single-course corticosteroid pulse therapy is not statistically, significantly different from triple-course in TSP protocol for improving renal outcome and preventing relapse in patients with IgAN. Single-course corticosteroid pulse therapy may become a treatment option for patients with IgAN.

Long-Term Outcome of ABO-Incompatible Kidney Transplantation in Patients Treated With Low-Dose Rituximab Regimen

BACKGROUND

Introduction of rituximab in the desensitization protocols for ABO-incompatible (ABOI) kidney transplantation (KTX) has afforded excellent results. However, the acceptability of minimal dosage of rituximab in these protocols remains to be defined.

METHODS

Sixty-three patients who underwent ABOI KTX were included in this study. The desensitization protocol consisted of plasmapheresis, tacrolimus, mycophenolate mofetil, methylprednisolone, intravenous immunoglobulin, basiliximab, and low-dose rituximab (100 mg/body). We evaluated the efficacy, safety, and long-term outcome of this protocol (group R, n = 39) and compared them with those of patients who underwent splenectomy (group S, n = 24).

RESULTS

Graft and patient survival at 10 years after KTX were comparable between the groups (94.4% [group R] vs 95.4% [group S] and 94.6% [group R] vs 95.8% [group S], respectively). The incidence of acute antibody-mediated rejection (AAMR) was similar in the 2 groups (10.2% vs 12.5%). There were no significant differences in the incidence of chronic active antibody-mediated rejection. Of the patients, 7 developed AAMR and 3 of these patients (1 in group R and 2 in group S) lost their grafts. There were no significant differences in the incidence of chronic active antibody-mediated rejection. The incidence of postoperative cytomegalovirus infection in group R was significantly lower than that in group S. Furthermore, the incidence of postoperative late-onset neutropenia was low in group R.

CONCLUSIONS

A low-dose rituximab regimen for ABOI KTX is acceptable for preventing AAMR with a low incidence of delayed adverse events.

A Case of Chronic Calcium Oxalate Nephropathy due to Short Bowel Syndrome and Cholecystectomy

Background

Oxalate nephropathy is a rare disease. Especially chronic oxalate nephropathy still has many unknown aspects as compared to acute oxalate nephropathy with relatively well-known causality.

Case Presentation

The patient was a 70-year-old woman who had a history of small bowel resection 25 years before, cholecystectomy 10 years before, and renal stones (calcium oxalate stones) 7 years before. She had been suffering from chronic diarrhea and had been treated by a local physician. The patient was found to have renal dysfunction (creatinine 3.09 mg/dL, eGFR 12.3 mL/min/1.73 m², hemoglobin 7.8 g/dL) and was referred to our department. The patient was admitted to our hospital for further investigation. Renal ultrasound showed hepatorenal echo contrast in an opposite manner and clear contrast between the renal cortex and medullary pyramid. Renal biopsy was performed, and histological examination showed tubulointerstitial disorder due to deposition of calcium oxalate. Daily urinary excretion of calcium oxalate was significantly increased. The patient was encouraged to drink water and administered vitamin B₆, citric acid, K and Na hydrate. Thereafter, her symptoms improved.

Conclusion

Case reports of chronic oxalate neuropathy are rare in the literature, and its underlying mechanism has not been understood. Our patient had a history of small bowel resection and cholecystectomy. We considered that her short bowel syndrome had influenced the development of calcium oxalate nephropathy.

Interferon-inducible Mx1 protein is highly expressed in renal tissues from treatment-naïve lupus nephritis, but not in those under immunosuppressive treatment

OBJECTIVES

The aim of this study was to clarify the consequences of Mx1, one of the IFN-inducible proteins, in the peripheral blood as well as in renal tissues in patients with systemic lupus erythematosus (SLE).

PATIENTS AND METHODS

Mx1 protein concentrations in (PBMCs) from 18 SLE patients mostly in their stable disease status, 11 IgA nephropathy (IgAN) patients, 5 ANCA-associated vasculitis (AAV) patients and 16 healthy controls were measured using enzyme-linked immunosorbent assay (ELISA). Mx1 expression in renal specimens from 18 patients with lupus nephritis (LN), 18 with IgAN and 10 with AAV were evaluated using immunohistochemistry.

RESULTS

Mx1 protein concentrations in lysates of PBMCs were significantly higher in SLE patients compared with those in other three groups. Mx1-positive area in renal tissues was significantly dominant in both glomeruli and renal tubules of LN compared with other renal diseases. Renal Mx1 protein levels were lower in LN after immunosuppressive treatment, compared with those from immunosuppressant-naïve patients.

CONCLUSION

Mx1 levels were upregulated in lupus peripheral blood even when their disease activities were stable. On the other hand, Mx1 was highly expressed in kidneys from patients with LN before treatment, which was decreased after immunosuppressive treatment. These results suggest that Mx1 is a potential marker for the diagnosis of SLE in the peripheral blood and also for the activity of lupus nephritis in the kidney.

Immunohistochemical identification of Propionibacterium acnes in granuloma and inflammatory cells of myocardial tissues obtained from cardiac sarcoidosis patients

Background

Although rare, cardiac sarcoidosis (CS) is potentially fatal. Early diagnosis and intervention are essential, but histopathologic diagnosis is limited. We aimed to detect Propionibacterium acnes, a commonly implicated etiologic agent of sarcoidosis, in myocardial tissues obtained from CS patients.

Methods and results

We examined formalin-fixed paraffin-embedded myocardial tissues obtained by surgery or autopsy and endomyocardial biopsy from patients with CS (n = 26; CS-group), myocarditis (n = 15; M-group), or other cardiomyopathies (n = 39; CM-group) using immunohistochemistry (IHC) with a P. acnes-specific monoclonal antibody. We found granulomas in 16 (62%) CS-group samples. Massive (≥14 inflammatory cells) and minimal (<14 inflammatory cells) inflammatory foci, respectively, were detected in 16 (62%) and 11 (42%) of the CS-group samples, 10 (67%) and 10 (67%) of the M-group samples, and 1 (3%) and 18 (46%) of the CM-group samples. P. acnes-positive reactivity in granulomas, massive inflammatory foci, and minimal inflammatory foci were detected in 10 (63%), 10 (63%), and 8 (73%) of the CS-group samples, respectively, and in none of the M-group and CM-group samples.

Conclusions

Frequent identification of P. acnes in sarcoid granulomas of originally aseptic myocardial tissues suggests that this indigenous bacterium causes granuloma in many CS patients. IHC detection of P. acnes in massive or minimal inflammatory foci of myocardial biopsy samples without granulomas may be useful for differentiating sarcoidosis from myocarditis or other cardiomyopathies.

Cytomegalovirus peritonitis after kidney transplantation diagnosed through histopathological examination

Among organ transplant recipients, cytomegalovirus (CMV) commonly results in various types of infection such as pneumonitis, hepatitis, and enterocolitis. However, CMV peritonitis is very rare and difficult to diagnose owing to lack of visible clinical signs. We present a case of a 35-year-old female kidney recipient who developed abdominal pain and urinary retention caused by CMV peritonitis. To our knowledge, this is the first case report of CMV peritonitis after organ transplantation to be diagnosed through histopathological examination.

De novo proliferative glomerulonephritis with monoclonal IgG deposits of the IgG1κ subtype in a kidney allograft

Proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits (PGNMID) has recently been described in cases with glomerular disease. Only 16 cases of recurrent or de novo PGNMID have been reported in the transplanted kidney. Here we report a case of de novo PGNMID in a renal allograft diagnosed in the early stage by protocol biopsy. A 41-year-old male with end-stage kidney disease caused by focal glomerular sclerosis received a living-related kidney transplant. The post-transplantation course was stable, except for an early episode of acute T cell-mediated rejection. Mesangial C1q deposition was found on the 3-year protocol biopsy. On the 4-year protocol biopsy, mild mesangioproliferative changes and deposition of IgG, C1q, C3, IgG1, and κ light chain were evident, confirming the diagnosis of PGNMID of the IgG1κ subtype. Furthermore, mild proteinuria was detected at that time. Because a subsequent haematological examination revealed high copy number Epstein-Barr virus (EBV) DNA and free κ light chain in blood, the post-transplant lymphoproliferative disorder (PTLD) was suspected. Mycophenolate mofetil (MMF) was discontinued and rituximab was administered for the treatment of PTLD; subsequently, the improvement in proteinuria and serum creatinine was found 2 months after rituximab administration.

Histones and Neutrophil Extracellular Traps Enhance Tubular Necrosis and Remote Organ Injury in Ischemic AKI

Severe AKI is often associated with multiorgan dysfunction, but the mechanisms of this remote tissue injury are unknown. We hypothesized that renal necroinflammation releases cytotoxic molecules that may cause remote organ damage. In hypoxia-induced tubular epithelial cell necrosis in vitro, histone secretion from ischemic tubular cells primed neutrophils to form neutrophil extracellular traps. These traps induced tubular epithelial cell death and stimulated neutrophil extracellular trap formation in fresh neutrophils. In vivo, ischemia-reperfusion injury in the mouse kidney induced tubular necrosis, which preceded the expansion of localized and circulating neutrophil extracellular traps and the increased expression of inflammatory and injury-related genes. Pretreatment with inhibitors of neutrophil extracellular trap formation reduced kidney injury. Dual inhibition of neutrophil trap formation and tubular cell necrosis had an additive protective effect. Moreover, pretreatment with antihistone IgG suppressed ischemia-induced neutrophil extracellular trap formation and renal injury. Renal ischemic injury also increased the levels of circulating histones, and we detected neutrophil infiltration and TUNEL-positive cells in the lungs, liver, brain, and heart along with neutrophil extracellular trap accumulation in the lungs. Inhibition of neutrophil extracellular trap formation or of circulating histones reduced these effects as well. These data suggest that tubular necrosis and neutrophil extracellular trap formation accelerate kidney damage and remote organ dysfunction through cytokine and histone release and identify novel molecular targets to limit renal necroinflammation and multiorgan failure.

Tacrolimus reduction with everolimus addition for calcineurin inhibitor-induced arteriolopathy in kidney allografts

AIM

The aim of this study was to evaluate the effect of tacrolimus (TAC) reduction with everolimus (EVR) addition on the maintenance immunosuppression for the recipients with calcineurin inhibitor arteriolopathy (CNIA).

METHODS

This retrospective study consisted of 13 kidney allograft recipients who were found to have CNIA on protocol biopsy specimens. The time of intervention was 9-89 months. All the patients were on TAC, mycophenolate mofetil (MMF). 9 of 13 were on steroid. EVR was added and TAC dose was reduced. MMF dose was not changed. Revaluation biopsy was taken 12 months after the intervention. TAC trough levels (TACC0 , ng/mL), EVR trough levels (EVRC0 , ng/mL), estimated glomerular filtration rate (eGFR, mL/min), and urine protein per creatinine (uP/Cr, g/g creatinine) were compared before and 1 year after intervention. Changes in pathological findings and adverse events were also reviewed.

RESULTS

Aah scores improved in 5 patients. Aah scores did not change in the rest of the patients. No deterioration was observed. No improvement was seen in those with aah3. TACC0 reduced from 3.3 to 2.3. EVRC0 at revaluation was 4.1. eGFR improved from 44.3 to 49.8. uP/Cr slightly increased from 0.20 to 0.26. EVR was discontinued in 1 patient due to an adverse event. EVR dose was reduced in 5 patients due to adverse events.

CONCLUSION

TAC reduction with EVR addition improves CNIA histologically in selected cases.

Microvascular inflammation in early protocol biopsies of renal allografts in cases of chronic active antibody-mediated rejection

AIM

Chronic active antibody-mediated rejection (chronic ABMR) is one important cause of late-stage renal allograft loss. However, few reports have used protocol biopsy to observe changes over time in cases that develop chronic ABMR. The aim of this study was to use protocol biopsy to clarify the histological features of cases that develop chronic ABMR.

METHODS

We recruited 379 ABO compatible patients who underwent protocol biopsy at our hospital from 2010 to 2014. Seventeen of these patients were diagnosed with chronic ABMR (chronic ABMR group), and 12 patients were class 2 donor-specific antibody (DSA) positive and were not diagnosed with chronic ABMR (class 2 DSA-positive group). With the addition of a control group consisting of 30 DSA negative patients, these three groups were compared for Banff factors in protocol biopsies taken 3 months, 6 months, 1 year, 3 years, and 5 years after the transplant.

RESULTS

Three months post transplant, the chronic ABMR group had a significantly higher number of patients exhibiting g + ptc > 0 than that in the control group (P = 0.01). At 1, 3, and 5 years post transplant, significantly more subjects in the chronic ABMR and class 2 DSA-positive groups compared with the control group exhibited g + ptc > 0 (P < 0.03). Five years post transplant, the chronic ABMR group exhibited a significantly higher mean c4d score than that in the control group (P = 0.02). The only significant difference observed between the chronic ABMR group and the class 2 DSA-positive group was in cg scores at 5 years post transplant, which were significantly higher in the chronic ABMR group (P = 0.03).

CONCLUSIONS

These results suggest that cases exhibiting microvascular inflammation in the early post-transplant period may develop chronic ABMR, and it would be highly beneficial to perform focused electron microscope surveillance of these cases.

Immunohistochemical evidence for the association between attenuated mTOR signaling and diffuse alveolar damage, a fatal lung complication

Targeted anticancer therapies have been developed to interfere with specific target molecules including those of downstream pathways required for tumor growth and progression. Mammalian target of rapamycin (mTOR) has been considered as one of the target molecules of cancer growth, and its inhibitors have been reported to exert an anticancer effect in various malignant tumors. The pulmonary disorder is one of the major side effects of anticancer drugs including mTOR inhibitor (mTORi), and the diagnosis of lung injury induced by medication is difficult because of non-specific nature of the radiological findings. In this study, we present the detailed autopsy findings of a patient who developed diffuse alveolar damage (DAD) following mTORi treatment for metastatic renal cell carcinoma. We also studied 19 cases of DAD derived from other diseases and 9 cases with non-pathological lung. Of interest, pneumocytes of the patients with DAD, who received other anticancer drugs or contacted bacteria, demonstrated significantly lower mTOR activities than pneumocytes of those with non-pathological lung tissue, as judged by the immunohistochemical analysis. In contrast, both pneumocytes and T cells in DAD tissues of the patient treated with mTORi showed higher mTOR activities than those of patients with DAD of other causes, suggesting that the enhanced mTOR signaling may be involved in the development of DAD after mTORi treatment. This unexpected finding needs to be confirmed in other patients treated with mTORi. In conclusion, the attenuated mTOR signaling in pneumocytes may contribute to the pathogenesis of DAD in patients without mTORi treatment.

De novo proteinuria with pathological evidence of glomerulonephritis after everolimus induction

A 68-year-old man who underwent living-unrelated kidney transplantation from his spousal donor was immunosuppressed with tacrolimus and mycophenolate mofetil. Despite his uneventful clinical course, protocol biopsy at 2 years post transplant showed de novo CNI tubulotoxicity despite low tacrolimus exposure. Everolimus was added in order to discontinue TACER. However, prominent proteinuria impeded continuation of everolimus since biopsy showed diffuse glomerular endocapillary proliferation without C4d deposition. No donor-specific antibody was detected. Pulse steroids were given and proteinuria returned to normal with histological reversal.

Tonsillectomy ameliorates histological damage of recurrent immunoglobulin A nephropathy after kidney transplantation

AIM

Recurrence of immunoglobulin A (IgA) nephropathy (IgAN) after renal transplantation is important as a cause of graft failure under improving rejection control. However, no specific therapy for recurrent IgAN is currently available. In this study, we evaluated the histological efficacy of tonsillectomy for allograft IgAN.

METHODS

Fifteen kidney recipients (male 9, female 6, mean age 40.9 ± 9.3 years), who received a diagnosis of IgA nephropathy by allograft biopsy, were enrolled in this study. Tonsillectomy was performed 44.1 ± 27.1 months after the kidney transplantation. All patients underwent a repeat graft biopsy at 23.8 ± 15.8 months after tonsillectomy.

RESULTS

Six patients had microhematuria before tonsillectomy. At 12 months after treatment, the microhematuria disappeared in five of these patients and one patient had mild hematuria. Three patients had severe proteinuria (more than 1.0 g/gCr) before tonsillectomy and improved after treatment. On histological analysis, four patients had acute lesions including cellular or fibrocellular crescents. The acute lesions disappeared after these treatments in all patients. Eleven patients had chronic lesions including global sclerosis, segmental sclerosis and fibrous crescents. The chronic lesion was ameliorated in six patients, unchanged in three and deteriorated in two patients.

CONCLUSIONS

Tonsillectomy improves not only clinical findings but also ameliorates histological damage caused by recurrent IgAN after kidney transplantation. Tonsillectomy is a novel and effective treatment for recurrent IgAN.

Long-term outcome in Japanese patients with lupus nephritis

The objective of this study was to clarify the long-term outcome in patients with lupus nephritis (LN) according to the International Society of Nephrology and Renal Pathology Society classification. This retrospective analysis comprised 186 Japanese patients given a diagnosis of LN by renal specimen with a mean observation period of 12 years. Primary end point was defined as death or end-stage renal disease, and standardized mortality ratios were calculated. Five patients presented with histopathological class I, 62 with II, 21 with III or III+V, 73 with IV or IV+V and 25 with V. Fourteen deaths occurred, corresponding to an overall standardized mortality ratio of 3.59 (95% confidence interval 2.02-5.81, p < 0.0001). Kaplan-Meier analysis revealed a 10-year overall survival of 95.7%. Nephrotic proteinuria (≥3.5 g/day) at baseline was identified as an independent poor prognostic factor for overall survival in Cox regression analysis. Kaplan-Meier analysis revealed a 10-year renal survival as 94.3%. Male gender and nephrotic proteinuria at baseline were identified as independent poor prognostic factors for renal survival in Cox regression analysis. In conclusion, LN was associated with a 3.59-fold increase in mortality compared with the general population. Male gender and nephrotic proteinuria were predictive for poor renal outcome.

[Complete resection of a posterior mediastinal tumor after preoperative identification of artery of Adamkiewicz]

The thoracolumbar spinal cord receives its blood supply primarily from the artery of Adamkiewicz (AA), a branch of thoracolumbar intercostal arteries. Aortic cross-clamping during operation for descending aortic aneurysms can cause paraplegia due to spinal cord ischemia secondary to low blood flow through the AA. A 69-year-old woman was diagnosed with a left posterior mediastinal tumor measuring 66 mm. The tumor was adjacent to the thoracic aorta between Th10 to Th12 vertebral levels. Preoperative 3-dimensional computed tomography (3D-CT) imaging revealed 2 AAs originated from the 10th and 11th left intercostal arteries just near the tumor. The patient underwent a left thoracotomy and the 2 intercostal arteries were carefully dissected from the encapsulated tumor. Complete resection was safely achieved with preservation of the AAs. Pathology revealed a schwannoma. There were no complications. In performing thoracic surgery for posterior mediastinal tumors, it is important to identify the AAs preoperatively and preserve them.

Japan Renal Biopsy Registry and Japan Kidney Disease Registry: Committee Report for 2009 and 2010

The Japan Renal Biopsy Registry (J-RBR) was started in 2007 and the Japan Kidney Disease Registry (J-KDR) was then started in 2009 by the Committee for Standardization of Renal Pathological Diagnosis and the Committee for the Kidney Disease Registry of the Japanese Society of Nephrology. The purpose of this report is to describe and summarize the registered data from 2009 and 2010. For the J-KDR, data were collected from 4,016 cases, including 3,336 (83.1 %) by the J-RBR and 680 (16.9 %) other cases from 59 centers in 2009, and from 4,681 cases including 4,106 J-RBR cases (87.7 %) and 575 other cases (12.3 %) from 94 centers in 2010, including the affiliate hospitals. In the J-RBR, 3,165 native kidneys (94.9 %) and 171 renal grafts (5.1 %) and 3,869 native kidneys (94.2 %) and 237 renal grafts (5.8 %) were registered in 2009 and 2010, respectively. Patients younger than 20 years of age comprised 12.1 % of the registered cases, and those 65 years and over comprised 24.5 % of the cases with native kidneys in 2009 and 2010. The most common clinical diagnosis was chronic nephritic syndrome (55.4 % and 50.0 % in 2009 and 2010, respectively), followed by nephrotic syndrome (22.4 % and 27.0 %); the most frequent pathological diagnosis as classified by the pathogenesis was IgA nephropathy (31.6 % and 30.4 %), followed by primary glomerular diseases (except IgA nephropathy) (27.2 % and 28.1 %). Among the primary glomerular diseases (except IgA nephropathy) in the patients with nephrotic syndrome, membranous nephropathy was the most common histopathology in 2009 (40.3 %) and minor glomerular abnormalities (50.0 %) were the most common in 2010 in native kidneys in the J-RBR. Five new secondary and longitudinal research studies by the J-KDR were started in 2009 and one was started in 2010.

Granulomatous tubulointerstitial nephritis in a renal allograft: three cases report and review of literature

Granulomatous interstitial nephritis (GIN) is a rare histologic diagnosis in renal allografts. We report three cases with GIN. Case 1: a 37-yr-old woman received a kidney from her mother. On follow-up 15 months later, serum creatinine was increased and a graft biopsy showed epithelioid granuloma in the center of massive mononuclear cell infiltration. She had presented with refractory urinary tract infection treated with antibiotics before biopsy. The case was presumed to be GIN associated with UTI or hypersensitivity to medication. Case 2: a 47-yr-old woman received a second graft from a non-heart-beating donor. A protocol graft biopsy was performed six months after transplantation and showed several granulomatous nodules. She was followed closely without therapy. Case 3: a 27-yr-old woman received an ABO-incompatible kidney from her father. A protocol graft biopsy was performed three months after transplantation and showed granulomatous reaction with severe mononuclear cell infiltration. She received steroid pulse therapy. The two latter patients had no obvious factor contributing to GIN. Therefore, they were presumed to have idiopathic GIN. Infection is considered to be the main causative factor of GIN in renal allografts. This paper describes rare cases of GIN that had no infectious episode in the renal allografts.

An undifferentiated embryonal sarcoma of the liver containing adipophilin-positive vesicles in an adult with massive sinusoidal invasion

Undifferentiated embryonal sarcoma of the liver (UESL) is a malignant mesenchymal tumor that occurs typically in children and rarely in adults. Here we describe a case of UESL in a 51-year-old woman who presented with a cystic lesion in the liver. Because it grew slowly, the anterior segment of the liver was resected to check the lesion. Histologically, the lesion looked like a telangiectatic hepatic adenoma. Two years after resection, the tumor recurred, and she died 3 years later due to liver failure. The autopsy revealed that these lesions were UESL with massive sinusoidal invasion, and a review of the case indicated the primary lesion was also UESL. We also confirmed these tumor cells by staining with CD56, alpha-smooth muscle actin (SMA), and adipophilin, suggesting that they have a character similar to that of stellate cells in the space of Disse. The histological result of our patient revealed atypical UESL. Therefore, UESL should be considered when a hepatic lesion with degeneration is seen, even in an adult. In addition, the immunohistochemical appearance of this case implies that UESL is perhaps derived from stellate cells or stellate cells with myofibroblast differentiation in the space of Disse.

Regional secondary focal segmental glomerulosclerosis in a transplanted kidney: resolution with treatment of a segmental renal artery stenosis

BACKGROUND

Conditions associated with high intraglomerular filtration pressure can cause secondary focal segmental glomerulosclerosis (FSGS). Unilateral renal artery stenosis (RAS) or its occlusion results in FSGS-like changes and the nephrotic syndrome in the contralateral kidney due to hyperfiltration. However, it has been rarely reported that stenosis of a renal arterial branch can result in FSGS-like changes in a different portion in the same kidney allograft.

CASE PRESENTATION

A 60-year-old male kidney recipient developed allograft dysfunction after angiotensin II receptor blockade for hypertension 4 months after transplantation. It was proven that one of two arterial branches of the graft was markedly stenotic. Graft dysfunction improved after percutaneous transluminal arterioplasty (PTA), however; the stenosis recurred and massive proteinuria developed 5 months later. Graft biopsy showed ischemic changes in the region fed by the stenotic artery branch and in contrast FSGS-like changes in the region fed by the other branch. His clinicopathological manifestation including massive proteinuria almost normalized after the repeat PTA.

CONCLUSION

Here we report a case of secondary FSGS of a kidney allograft due to severe RAS of a branch of the same kidney, in which clinical and pathological improvement were confirmed after radiological intervention. When moderate to severe proteinuria appear, secondarily developed FSGS as well as primary (recurrent or de novo) FSGS should be taken into account in kidney transplant recipients.

A case of progressive thrombotic microangiopathy after ABO-incompatible renal transplantation

A 21-yr-old man of blood type O receiving hemodialysis for IgA nephropathy underwent living-related ABO-incompatible (ABOI) renal transplantation from his mother, whose blood type is A. He was negative for flow cross-match, anti-human leukocyte antigen (HLA) antibody, and anti-MICA antibody. Pre-treatment anti-A IgG titer was 1:256. Desensitization consisted of tacrolimus, mycophenolate mofetil, methylprednisolone, rituximab, and plasmapheresis. He developed acute antibody rejection at day 2 post-transplant, which was successfully treated. After renal artery reconstruction surgery at day 91 for renovascular hypertension caused by renal artery stricture, the patient suffered from acute prostatitis, which subsequently induced type III acute antibody-mediated rejection. Even after recovery from the rejection after temporary hemodialysis, graft function progressively deteriorated and consecutive allograft biopsy showed progressive thrombotic microangiopathy (TMA) without any evidence of donor-specific antibody other than anti-A antibody. The tacrolimus dose was kept low for fear of tacrolimus-induced TMA. Despite these efforts, the patient resumed hemodialysis six months' post-transplant.

Japan Renal Biopsy Registry: the first nationwide, web-based, and prospective registry system of renal biopsies in Japan

BACKGROUND

The Committee for the Standardization of Renal Pathological Diagnosis and the Working Group for Renal Biopsy Database of the Japanese Society of Nephrology started the first nationwide, web-based, and prospective registry system, the Japan Renal Biopsy Registry (J-RBR), to record the pathological, clinical, and laboratory data of renal biopsies in 2007.

METHODS

The patient data including age, gender, laboratory data, and clinical and pathological diagnoses were recorded on the web page of the J-RBR, which utilizes the system of the Internet Data and Information Center for Medical Research in the University Hospital Medical Information Network. We analyzed the clinical and pathological diagnoses registered on the J-RBR in 2007 and 2008.

RESULTS

Data were collected from 818 patients from 18 centers in 2007 and 1582 patients from 23 centers in 2008, including the affiliated hospitals. Renal biopsies were obtained from 726 native kidneys (88.8%) and 92 renal grafts (11.2%) in 2007, and 1400 native kidneys (88.5%) and 182 renal grafts (11.5%) in 2008. The most common clinical diagnosis was chronic nephritic syndrome (47.4%), followed by nephrotic syndrome (16.8%) and renal transplantation (11.2%) in 2007. A similar frequency of the clinical diagnoses was recognized in 2008. Of the native kidneys, the most frequent pathological diagnosis as classified by pathogenesis was immunoglobulin (Ig) A nephropathy (IgAN) both in 2007 (32.9%) and 2008 (30.2%). Among the primary glomerular diseases (except IgAN), membranous nephropathy (MN) was the most common disease both in 2007 (31.4%) and 2008 (25.7%).

CONCLUSIONS

In a cross-sectional study, the J-RBR has shown IgAN to be the most common disease in renal biopsies in 2007 and 2008, consistent with previous Japanese studies. MN predominated in the primary glomerular diseases (except for IgAN). The frequency of the disease and the clinical and demographic correlations should be investigated in further analyses by the J-RBR.

Incidentally detected parafalcine chondrosarcoma

Parafalcine chondrosarcoma is extremely rare, and may be difficult to differentiate preoperatively from falx meningioma. An 18-year-old woman presented with a parafalcine chondrosarcoma incidentally detected as a small lesion 2 years before admission, suggesting falx meningioma. Brain computed tomography and magnetic resonance imaging just before admission revealed the parafalcine lesion had increased by about nine times in volume during the last 2 years. Single-photon emission computed tomography (SPECT) after intravenous administration of both thallium-201 chloride ((201)TlCl) and N-isopropyl-p-[(123)I]iodoamphetamine ((123)I-IMP) demonstrated no abnormal uptake of either tracer. Histological examination revealed classic low-grade chondrosarcoma. Parafalcine chondrosarcoma should be considered at this site if relatively rapid growth is observed. SPECT using (201)TlCl and (123)I-IMP may be useful to discriminate parafalcine low-grade chondrosarcoma from meningioma or other tumours originating in this region.

Pleural involvement of dialysis-related amyloidosis

Two cases of pleural involvement of dialysis-related amyloidosis (DRA) with pleural effusion are presented. DRA is one of the most important complications in long-term dialysis patients and beta2-microglobulin is the principal protein component of DRA, but pleural deposition of beta2-microglobulin amyloid has not yet been reported. To the best of the authors' knowledge, this is the first case report of pleural involvement of DRA presenting with pleural effusion. This case study suggests that pleural involvement of DRA should be considered when exudative pleural effusion is observed in patients undergoing long-term dialysis.

Estimation of preservative concentrations in foods and their daily intake based on official inspection results in Japan in fiscal year 1998

The mean concentration and daily intake of five preservatives were estimated based on the results of an analysis of 89,927 samples of food obtained in official inspections by Japanese local governments in fiscal year 1998. The mean concentration of benzoic acid was 9.5% of the allowable limit, and those of dehydroacetic acid, p-hydroxybenzoic acid, propionic acid, and sorbic acid were 1.5%, 5.7%, 1.7%, and 23.9%, respectively. Daily intake levels of these preservatives per person estimated from the concentration and daily consumption of foods were 6.23 mg, 0.0303 mg, 1.02 mg, 8.10 mg, and 25.0 mg, respectively, and assuming a body weight of 50 kg, the amounts of benzoic acid, p-hydroxybenzoic acid, and sorbic acid consumed were 2.5%, 0.2%, and 2.0% of their acceptable daily intakes, respectively. These values were similar to those obtained based on the results of the official inspections in fiscal years 1994 and 1996.

Human L-type amino acid transporter 1 (LAT1): characterization of function and expression in tumor cell lines

System L is a major nutrient transport system responsible for the transport of large neutral amino acids including several essential amino acids. We previously identified a transporter (L-type amino acid transporter 1: LAT1) subserving system L in C6 rat glioma cells and demonstrated that LAT1 requires 4F2 heavy chain (4F2hc) for its functional expression. Since its oncofetal expression was suggested in the rat liver, it has been proposed that LAT1 plays a critical role in cell growth and proliferation. In the present study, we have examined the function of human LAT1 (hLAT1) and its expression in human tissues and tumor cell lines. When expressed in Xenopus oocytes with human 4F2hc (h4F2hc), hLAT1 transports large neutral amino acids with high affinity (K(m)= approximately 15- approximately 50 microM) and L-glutamine and L-asparagine with low affinity (K(m)= approximately 1.5- approximately 2 mM). hLAT1 also transports D-amino acids such as D-leucine and D-phenylalanine. In addition, we show that hLAT1 accepts an amino acid-related anti-cancer agent melphalan. When loaded intracellularly, L-leucine and L-glutamine but not L-alanine are effluxed by extracellular substrates, confirming that hLAT1 mediates an amino acid exchange. hLAT1 mRNA is highly expressed in the human fetal liver, bone marrow, placenta, testis and brain. We have found that, while all the tumor cell lines examined express hLAT1 messages, the expression of h4F2hc is varied particularly in leukemia cell lines. In Western blot analysis, hLAT1 and h4F2hc have been confirmed to be linked to each other via a disulfide bond in T24 human bladder carcinoma cells. Finally, in in vitro translation, we show that hLAT1 is not a glycosylated protein even though an N-glycosylation site has been predicted in its extracellular loop, consistent with the property of the classical 4F2 light chain. The properties of the hLAT1/h4F2hc complex would support the roles of this transporter in providing cells with essential amino acids for cell growth and cellular responses, and in distributing amino acid-related compounds.

Transport properties of a system y+L neutral and basic amino acid transporter. Insights into the mechanisms of substrate recognition

The properties of system y(+)L-mediated transport were investigated on rat system y(+)L transporter, ry(+)LAT1, coexpressed with the heavy chain of cell surface antigen 4F2 in Xenopus oocytes. ry(+)LAT1-mediated transport of basic amino acids was Na(+)-independent, whereas that of neutral amino acids, although not completely, was dependent on Na(+), as is typical of system y(+)L-mediated transport. In the absence of Na(+), lowering of pH increased leucine transport, without affecting lysine transport. Therefore, it is proposed that H(+), besides Na(+) and Li(+), is capable of supporting neutral amino acid transport. Na(+) and H(+) augmented leucine transport by decreasing the apparent K(m) values, without affecting the V(max) values. We demonstrate that although ry(+)LAT1-mediated transport of [(14)C]l-leucine was accompanied by the cotransport of (22)Na(+), that of [(14)C]l-lysine was not. The Na(+) to leucine coupling ratio was determined to be 1:1 in the presence of high concentrations of Na(+). ry(+)LAT1-mediated leucine transport, but not lysine transport, induced intracellular acidification in Chinese hamster ovary cells coexpressing ry(+)LAT1 and 4F2 heavy chain in the absence of Na(+), but not in the presence of physiological concentrations of Na(+), indicating that cotransport of H(+) with leucine occurred in the absence of Na(+). Therefore, for the substrate recognition by ry(+)LAT1, the positive charge on basic amino acid side chains or that conferred by inorganic monovalent cations such as Na(+) and H(+), which are cotransported with neutral amino acids, is presumed to be required. We further demonstrate that ry(+)LAT1, due to its peculiar cation dependence, mediates a heteroexchange, wherein the influx of substrate amino acids is accompanied by the efflux of basic amino acids.

Identification and characterization of a Na(+)-independent neutral amino acid transporter that associates with the 4F2 heavy chain and exhibits substrate selectivity for small neutral D- and L-amino acids

A cDNA was isolated from the mouse brain that encodes a novel Na(+)-independent neutral amino acid transporter. The encoded protein, designated as Asc-1 (asc-type amino acid transporter 1), was found to be structurally related to recently identified mammalian amino acid transporters for the transport systems L, y(+)L, x(C)(-), and b(0,+), which are linked, via a disulfide bond, to the type II membrane glycoproteins, 4F2 heavy chain (4F2hc), or rBAT (related to b(0,+) amino acid transporter). Asc-1 required 4F2hc for its functional expression. In Western blot analysis in the nonreducing condition, a 118-kDa band, which seems to correspond to the heterodimeric complex of Asc-1 and 4F2hc, was detected in the mouse brain. The band shifted to 33 kDa in the reducing condition, confirming that Asc-1 and 4F2hc are linked via a disulfide bond. Asc-1-mediated transport was not dependent on the presence of Na(+) or Cl(-). Although Asc-1 showed a high sequence homology (66% identity at the amino acid level) to the Na(+)-independent broad scope neutral amino acid transporter LAT2 (Segawa, H., Fukasawa, Y., Miyamoto, K., Takeda, E., Endou, H., and Kanai, Y. (1999) J. Biol. Chem. 274, 19745-19751), Asc-1 also exhibited distinctive substrate selectivity and transport properties. Asc-1 preferred small neutral amino acids such as Gly, L-Ala, L-Ser, L-Thr, and L-Cys, and alpha-aminoisobutyric acid as substrates. Asc-1 also transported D-isomers of the small neutral amino acids, in particular D-Ser, a putative endogenous modulator of N-methyl-D-aspartate-type glutamate receptors, with high affinity. Asc-1 operated preferentially, although not exclusively, in an exchange mode. Asc-1 mRNA was detected in the brain, lung, small intestine, and placenta. The functional properties of Asc-1 seem to be consistent with those of a transporter subserving the Na(+)-independent small neutral amino acid transport system asc.

Identification and functional characterization of a Na+-independent neutral amino acid transporter with broad substrate selectivity

We have isolated a cDNA from rat small intestine that encodes a novel Na+-independent neutral amino acid transporter with distinctive characteristics in substrate selectivity and transport property. The encoded protein, designated L-type amino acid transporter-2 (LAT-2), shows amino acid sequence similarity to the system L Na+-independent neutral amino acid transporter LAT-1 (Kanai, Y., Segawa, H., Miyamoto, K., Uchino, H., Takeda, E., and Endou, H. (1998) J. Biol. Chem. 273, 23629-23632) (50% identity) and the system y+L transporters y+LAT-1 (47%) and KIAA0245/y+LAT-2 (45%) (Torrents, D., Estevez, R., Pineda, M., Fernandez, E., Lloberas, J., Shi, Y.-B., Zorzano, A., and Palacin, M. (1998) J. Biol. Chem. 273, 32437-32445). LAT-2 is a nonglycosylated membrane protein. It requires 4F2 heavy chain, a type II membrane glycoprotein, for its functional expression in Xenopus oocytes. LAT-2-mediated transport is not dependent on Na+ or Cl- and is inhibited by a system L-specific inhibitor, 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH), indicating that LAT-2 is a second isoform of the system L transporter. Compared with LAT-1, which prefers large neutral amino acids with branched or aromatic side chains, LAT-2 exhibits remarkably broad substrate selectivity. It transports all of the L-isomers of neutral alpha-amino acids. LAT-2 exhibits higher affinity (Km = 30-50 microM) to Tyr, Phe, Trp, Thr, Asn, Ile, Cys, Ser, Leu, Val, and Gln and relatively lower affinity (Km = 180-300 microM) to His, Ala, Met, and Gly. In addition, LAT-2 mediates facilitated diffusion of substrate amino acids, as distinct from LAT-1, which mediates amino acid exchange. LAT-2-mediated transport is increased by lowering the pH level, with peak activity at pH 6.25, because of the decrease in the Km value without changing the Vmax value. Because of these functional properties and a high level of expression of LAT-2 in the small intestine, kidney, placenta, and brain, it is suggested that the heterodimeric complex of LAT-2 and 4F2 heavy chain is involved in the trans-cellular transport of neutral amino acids in epithelia and blood-tissue barriers.

Retention mechanism of imidazoles in connective tissue. IV. Identification of a nucleophilic imidazolone metabolite in rats

Formation of a nucleophilic 4(5H)(or 5(4H))-imidazolone structure has been postulated from in vitro studies to be one of the causative elements involved in the retention of drugs with imidazole moiety in connective tissue. To confirm this, we searched for the imidazolone-related metabolite in rats after intravenous dosing of 2-methylimidazole (2MI; 14C-labeled and unlabeled form, 3 and 300 micromol/kg body weight) as a model compound. The excreted urine, the major route of elimination of the compound, was collected and analyzed using the HPLC/MS system with a counterion effect for metabolite separation. 2-Methyl-4(5H)(or 5(4H))-imidazolone (2MIone) was identified as a urinary metabolite by chromatographic and mass-spectral inspection with the corresponding authentic standard. Pretreatment of rats with either SKF-525A (50 mg/kg, i.p.) or cimetidine (200 mg/kg, i.p.) significantly increased the excreted amount of 2MIone in urine and the irreversible binding of 2MI equivalents in the aortic tissue, whereas both factors were reduced by pretreatment with triethylenetetramine dihydrochloride (150 mg/kg/d for 5 d, s.c.). These results support the aforementioned deduction, and also raise the possibility that a cytochrome P450-independent, copper-related metabolic reaction might be involved in the imidazolone formation in vivo.

Retention mechanism of imidazoles in connective tissue. III. Aldehyde adduct formation of a 4(5H)(or5(4H))-imidazolone product in vitro

2-Methylimidazole (2MI), as well as imidazole, has been thought to undergo cupro-ascorbate (Cu-VC)-catalyzed oxidative transformation in vitro to become a reactive species capable of combining with aldehydes intrinsic to connective-tissue proteins. We attempted to seize the essence of the above reaction through obtaining the structural information of an aldehyde-bonding species. As major products from 2MI in the in vitro Cu-VC system, 2-hydroxymethylimidazole (2(OH)MI) and 2-methyl-4(5H)(or 5(4H))-imidazolone (2MIone) were identified by mass-spectral and chromatographic comparison with the corresponding authentic standards synthesized. The in situ addition of acetaldehyde or propionaldehyde as a simple protein-aldehyde model to the system resulted in the deducible formation of an aldol condensate, 2-methyl-4(or 5)-ethylidene-4(5H)(or 5(4H))-imidazolone (2MEIone) or its possible analogue with a propylidene moiety, respectively. The authentic compound of 2MIone directly reacted with acetaldehyde and easily afforded the products assignable to the isomers of 2MEIone through the ethylidene moiety at physiological pH and temperature, whereas neither 2MI or 2(OH)MI reacted at all. These results suggest that a 4(5H)(or 5(4H))-imidazolone product, although simply a monooxygenated form, is sufficiently reactive to give aldol condensation-typed covalent adducts with aldehydes, even under physiological conditions, probably having an activated methylene moiety in the ring structure. Based on the present results, we discussed the mechanism of the retention of imidazole-containing drugs in connective tissue.

Mutation in pncA is a major mechanism of pyrazinamide resistance in Mycobacterium tuberculosis

OBJECTIVE

To characterize the correlation of the mutations in the pncA gene encoding pyrazinamidase (PZase) of Mycobacterium tuberculosis to a loss of PZase activity and development of pyrazinamide (PZA) resistance.

DESIGN

The association of PZase activity, minimum inhibitory concentrations (MICs), and mutations in the pncA gene of M. tuberculosis isolated in mostly Asian countries was investigated.

RESULTS

One hundred thirty-five out of 168 isolates were PZase positive, and 33 were negative. The MICs of PZA at pH 6.0 were over 400 micrograms/ml for all 33 PZase-negative isolates, while those of PZase-positive isolates were equal to or less than 200 micrograms/ml. Among 33 PZase-negative isolates sequenced, 32 (97%) had mutations within the pncA gene. A mutation was seen in various regions throughout the pncA gene. It was surprising that all three strains of in vitro selected PZA resistant mutants were PZase-positive and showed no change in the pncA gene. These results indicate that additional mechanisms may be involved in PZA resistance. No mutations were observed in all of 135 PZase-positive M. tuberculosis isolates tested, indicating that mutations in the pncA gene could be involved in the loss of PZase activity.

CONCLUSIONS

Sequencing analysis of the pncA gene should provide rapid diagnosis of PZA resistant clinical isolates of M. tuberculosis.

Solitary fibrous tumor of the pleura causing recurrent hypoglycemia by secretion of insulin-like growth factor II

A case of malignant solitary fibrous tumor (SFT) is reported, occurring in a 61-year-old man with frequent hypoglycemia. Endocrinological analyses showed high serum levels of insulin-like growth factor II (IGF-II) and suppressed secretion of insulin. After the removal of a pleural tumor, which weighed 3150 g, serum IGF-II levels returned to normal and hypoglycemic attacks ceased. The tumor was composed of uniform spindle cells arranged in bundles, and fascicles with varying amounts of collagen and reticulin fibers. Mitotic figures at the rate of 6/10 high-power fields, and frequent foci of necrosis and hemorrhage were seen. Almost all of the tumor cells were immunohistochemically positive for vimentin and CD34. Electron microscopy revealed the immature mesenchymal or myofibroblastic nature of the tumor cells. These findings are consistent with malignant SFT of the pleura. Moreover, the tumor produced IGF-II mRNA as demonstrated by northern blot analysis. Thus, hypoglycemia of this patient was induced by SFT through the production and secretion of IGF-II.