Increased number of mitochondria in capillaries distributed in stroke‐like lesions of two patients with MELAS

We investigated two autopsy cases of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke‐like episodes (MELAS) using immunohistochemical staining with an anti‐mitochondrial antibody against translocase of the outer membrane 20 (TOMM20). In case 1, the patient was a 42‐year‐old man with a disease duration of 53 days, and in case 2, the patient was a 62‐year‐old woman with a disease duration of 27 months. In both the cases autopsy revealed moderate atrophy of the cerebrum and cerebellum and multifocal necrotizing lesions, irrespective of the vascular territory. Case 1 showed multiple areas with total necrosis in the cortex, accompanied by increases in number of protoplasmic astrocytes and acidophilic neurons as well as axonal swelling, suggestive of acute or subacute stage stroke‐like lesions (SLLs). In case 2, most of the SLLs displayed laminar spongy change in a rarefied cortex, and were considered to be at the chronic stage. In both the cases, capillary proliferation was noted within the SLLs, particularly in the acute phase. Endothelial cells of proliferating capillaries were strongly positive for TOMM20. In the cortex outside the SLLs, microvessels displayed only a fine granular immunoreactivity, as is seen in the controls. Although smooth muscle cells and endothelial cells in pial arteries and arterioles were also strongly positive for TOMM20, the territories of the affected pial arteries and arterioles did not correlate with the distribution of the SLLs. Although MELAS is characterized by recurrent stroke‐like episodes (SLEs), the pathogenetic relationship between SLEs and mitochondrial angiopathy remains unknown. An aberrant increase of mitochondria in the capillary endothelial cells of SLLs may disturb endothelial function, thus playing a role in the formation or development of SLLs.     

Heparanase: a key enzyme in invasion and metastasis of gastric carcinoma.

Previous reports have shown that the biochemical activity of heparanase is significantly correlated with the invasion and metastasis of malignant cells in vitro. Recently, it was found that the human heparanase gene was cloned and highly expressed in malignant cell lines and human solid malignant tumors. In the present study, we investigated the heparanase mRNA expression by using in situ hybridization in 116 paraffin-embedded tissues of primary gastric carcinomas. To explore its clinicopathologic significance, it was detected in the various steps of tumor progression and then compared with prognostic indicators. As a result, the heparanase expression was more prevalent in late-stage rather than early-stage carcinomas (P <.0001) and was more frequent in tumors of large size (P =.0212). Expression also correlated with lymphatic (P =.0086) and venous (P =.0171) invasion and with negative prognostic factors such as lymph nodal (P <.0001) and distant (P =.0221) metastases. However, in a multivariate analysis, messenger RNA expression of heparanase was not an independent prognostic factor. It was concluded that heparanase might play an important role in the development of invasion and metastasis of the gastric cancer. It was indicated that patients with heparanase-positive gastric carcinoma would have a greater chance of metastasis with a poor prognosis.     

Association of antipituitary antibody and type 2 iodothyronine deiodinase antibody in patients with autoimmune thyroid disease

Antipituitary antibody (APA) has been reported to be detected in patients with autoimmune thyroid disease. Type 2 iodothyronine deiodinase (D2) is expressed in both pituitary gland and thyroid gland. We studied the association of APA and D2 peptide antibody in patients with autoimmune thyroid disease. Rat pituitary gland homogenate and D2 peptide were used as antigens in the present study. APA and D2 peptide antibodies were measured by enzyme-linked immunosorbent assay (ELISA) in sera obtained from 42 patients with Hashimoto's disease, 26 patients with Graves' disease and 70 healthy control subjects. Moreover, D2 activity precipitation assay was performed in some patients with Hashimoto's disease. APA and D2 peptide antibody were elevated in patients with Hashimoto's disease and patients with Graves' disease, compared with control subjects. APA was positive in 32.4% (22/68), D2 peptide antibody was positive in 26.5% (18/68) of patients with autoimmune thyroid disease. APA was positive in 31.0% (13/42) of patients with Hashimoto's disease and 34.6% (9/26) of patients with Graves' disease. D2 peptide antibody was positive in 26.2% (11/42) of patients with Hashimoto's disease and 26.9% (7/26) of patients with Graves' disease. D2 peptide antibody was correlated with APA in patients with autoimmune thyroid disease. Moreover, precipitation of D2 activity was increased in some patients with Hashimoto's disease including a patient who also had idiopathic diabetes insipidus, and was correlated with D2 peptide antibody. These results suggest that D2 antibody may be associated with APA in patients with autoimmune thyroid disease.     

Heparin-induced thrombocytopenia in a uremic patient requiring hemodialysis: an alternative treatment and reexposure to heparin.

Heparin-induced thrombocytopenia (HIT) is an uncommon but potentially serious complication of hemodialysis, and subsequent reexposure to heparin after the disappearance of antiheparin-PF4 complex antibodies (HIT antibody) has been controversial. We report a 60-year-old woman who was sensitized to unfractionated heparin (heparin) as anticoagulant during hemodialysis (HD) and heparin flush on a nonsession day. The patient suddenly developed acute systemic reactions with acute pulmonary embolism a few minutes after manipulation with heparin flush on day 9, a nonsession day. Although there was no evidence of pulmonary embolism on a pulmonary scintigram on the next day, the fifth HD session was discontinued owing to recurrence of acute systemic reactions and massive clots in the dialyzer 30 min into the session. After confirmation of the presence of HIT antibody and maturation of vascular access fistula, a sixth HD session was carried out with argatroban, a synthetic direct thrombin inhibitor, with a bolus of 10 mg and continuous infusion of 0.5 mg/kg/hr as an alternative to heparin. Optimal dose adjustment of argatroban through activated partial thromboplastin time (APTT) monitoring led to a bolus of 5 mg and continuous infusion of 0.15 mg/kg/hr. The patient's HD treatment at the same doses 3 times a week followed an uneventful course over 6 months. HIT antibody was seronegative about 40 days after the cessation of heparin treatment. Reexposure to heparin was attempted with the monitoring of HIT antibody and platelet counts before and after the sessions on day 210. The titers of HIT antibody compared with before the level of reexposure showed a transient insignificantly small peak, and dialysis with heparin has been maintained to date with no recurrence of HIT. The measurement of HIT antibody titer could be useful in assessing not only the effect of argatroban to replace heparin but also in predicting the recurrence of HIT due to reexposure.     

Induction of thyroid-stimulating hormone receptor autoimmunity in hamsters

Female Chinese hamsters (n = 10) were immunized with Chinese hamster ovary (CHO) cells that expressed the human TSH receptor (TSHR) to generate a model of Graves' disease. TSHR-autoantibodies (TSHR-Ab) were determined by CHO-TSHR. Two hamsters with stimulating TSHR-Ab showed thyrocyte hypertrophy associated with a focal lymphocytic infiltration. CHO-TSHR were then stimulated with interferon gamma to enhance major histocompatibility complex class II expression. However, after immunization no stimulating TSHR-Ab were detected, but blocking TSHR-Ab were found in three of five animals. The thyroid glands from these hamsters showed marked thinning of thyroid epithelial cells, indicative of early thyroid atrophy consistent with a TSHR blocking antibody, but no lymphocytic infiltration. Lastly, female Armenian hamsters were immunized with an adenovirus construct incorporating wild-type TSHR. High titers of TSHR-Ab were induced effectively, but the thyroid hypertrophy observed was not associated with a lymphocyte infiltration. In summary, we demonstrated that the hamster could serve as a model of TSHR autoimmunity and that an adenoviral vector produced higher levels of TSHR-Ab than more conventional immunization with cells. The data also indicated that the intrathyroidal cellular immunity in this model was not related to TSHR-Ab formation and was an independent reflection of the T-cell immune response to TSHR antigen.     

Microscopic-sized "microthymoma" in patients with myasthenia gravis

BACKGROUND: In 2005, Cheuk et al reported two patients with microscopic-sized thymomas and proposed the term microthymoma to distinguish it from the nodular hyperplasia of thymic epithelium, so-called microscopic thymoma. Here, we present microthymomas that were found in 196 patients with myasthenia gravis (MG) who had undergone thymectomy. MATERIALS AND METHODS: Thymic tissues in 196 patients with MG who underwent thymectomy or thymothymomectomy were examined. Of these patients, 73 patients had thymoma indicated by CT before surgery, and the other 123 patients had no mediastinal tumors. From the resected thymic tissues, an average of 14 hematoxylin-eosin-stained sections (range, 4 to 55 sections) were prepared for microscopic examination. The histologic type of the thymoma was classified according to the World Health Organization (WHO) classification. RESULTS: From the 196 patients, we found three microthymomas in 3 patients (1.5%). While these three tumors could not be seen grossly in pathology section, they were found microscopically (range, 2 to 4 mm). The histologic subtype according to the WHO classification system was B1 in one patient and B2 in two patients. CONCLUSION: Microthymoma was found in 3 of 196 patients (1.5%) with MG. Microthymoma might exist in thymus of patients with MG, even in patients who have no thymoma indicated by CT.     

Decrease of intrathyroidal CD161+Valpha24+Vbeta11+ NKT cells in Graves' disease

To clarify changes in the intrathyroidal natural killer T (NKT) cell subset, which prevents autoimmunity in patients with Graves' disease (GD), we examined intrathyroidal and peripheral lymphocytes in 11 patients with GD and peripheral lymphocytes in nine healthy volunteers using three-color flow cytometry. The proportion of CD161 (+) T cell receptor Valpha24 (+) Vbeta11 (+) cells, which represent the NKT cell subset, was lower in the thyroid of patients with GD than in the peripheral blood of the same patients and in the peripheral blood of healthy subjects. These results indicate that the proportion of intrathyroidal NKT cells is decreased in patients with GD and that this decrease may contribute to incomplete regulation of autoreactive T cells in GD.     

Cleaved bovine prolactin-related protein-I stimulates vascular endothelial cell proliferation

Prolactin-related protein-I (PRP1) is a member of a non-classical prolactin (PRL)/growth hormone family in cattle. However, its function is still unknown. PRL, when cleaved by cathepsin D and matrix metalloproteinases (MMPs), resulted in cleaved N-terminal 16 kDa fragments (16K-PRL) that have antiangiogenetic properties in human and rodents. We examined the possibility of similar activity of bovine PRP1. PRP1 (normally 33 kDa) was cleaved by cathepsins (CTSs), MMPs, and bovine cotyledonary-conditioned medium (BCCM), and generated mainly 26 kDa N-terminal fragments. Two specific enzyme families, CTSs and MMPs cleaved intact PRP1, and BCCM also contained PRP1 cleavage activity. Bioactivity for pro- or anti-angiogenesis of the cleaved PRP1 was examined in a cell proliferation assay using bovine brain vascular endothelial cells. The cleaved PRP1 proliferated the endothelial cells in vitro. The endothelial cell proliferation activity of cleaved PRP1 may be shared in specific bovine placentomal angiogenesis.