Role of the C2A domain of synaptotagmin in transmitter release as determined by specific antibody injection into the squid giant synapse preterminal.

Squid synaptotagmin (Syt) cDNA, including its open reading frame, was cloned and polyclonal antibodies were obtained in rabbits immunized with glutathione S-transferase (GST)-Syt-C2A. Binding assays indicated that the antibody, anti-Syt-C2A, recognized squid Syt and inhibited the Ca(2+)-dependent phospholipid binding to the C2A domain. This antibody, when injected into the preterminal at the squid giant synapse, blocked transmitter release in a manner similar to that previously reported for the presynaptic injection of members of the inositol high-polyphosphate series. The block was not accompanied by any change in the presynaptic action potential or the amplitude or voltage dependence of the presynaptic Ca2+ current. The postsynaptic potential was rather insensitive to repetitive presynaptic stimulation, indicating a direct effect of the antibody on the transmitter release system. Following block of transmitter release, confocal microscopical analysis of the preterminal junction injected with rhodamine-conjugated anti-Syt-C2A demonstrated fluorescent spots at the inner surface of the presynaptic plasmalemma next to the active zones. Structural analysis of the same preparations demonstrated an accumulation of synaptic vesicles corresponding in size and distribution to the fluorescent spots demonstrated confocally. Together with the finding that such antibody prevents Ca2+ binding to a specific receptor in the C2A domain, these results indicate that Ca2+ triggers transmitter release by activating the C2A domain of Syt. We conclude that the C2A domain is directly related to the fusion of synaptic vesicles that results in transmitter release.     

Autoantibodies specific to hnRNP K: a new diagnostic marker for immune pathophysiology in aplastic anemia

To identify a new diagnostic marker for the immune pathophysiology of aplastic anemia (AA), we screened sera of immune-mediated AA patients for the presence of antibodies (Abs) specific to proteins derived from a leukemia cell line UT-7 using two-dimensional electrophoresis followed by immunoblotting. The target proteins were identified by peptide mass fingerprinting. Heterogeneous nuclear ribonucleoprotein (hnRNP) K was identified as a novel autoantigen. An enzyme-linked immunosorbent assay revealed high titers of anti-hnRNP K Abs in 85 (31%) of 273 patients with AA. Sixty-four patients received antithymocyte globulin and cyclosporine after undergoing screening for anti-hnRNP K Ab, anti-DRS-1 Ab, anti-moesin Ab, and paroxysmal nocturnal hemoglobinuria (PNH)-type cells. Twenty (87%) of 23 patients with the presence of anti-hnRNP K Abs responded to the immunosuppressive therapy (IST), while 19 (46%) of 41 patients without the presence of anti-hnRNP K Abs responded. A multivariate analysis showed only PNH-type cells and anti-hnRNP K Abs to be significant factors for the prediction of a good response to IST. The detection of anti-hnRNP K Abs as well as PNH-type cells may therefore be useful for diagnosing the immune pathophysiology of AA.     

Intraoperative patellar tendon strain: predicting the range of knee flexion after total knee arthroplasty

Background  The preoperative range of motion is an important factor that influences the range of motion after total knee arthroplasty. Because the length and tightness of the extensor mechanism are extracapsular elements with an influence on knee flexion, it is reasonable to assume that the tension of the knee extensor mechanism during surgery has a considerable impact on the postoperative range of motion. The purpose of this study was to determine the influence of the tightness of knee extensor mechanism on postoperative knee flexion. Methods  In 18 knees undergoing posterior-stabilized type total knee arthroplasty, we measured the longitudinal strain on the patellar tendon with all the components in position during passive knee flexion up to 135°. The patellar tendon strains measured during surgery were compared with the preoperative maximum knee flexion angle and postoperative maximum knee flexion angle at 1 year. Results  There was a significant inverse correlation between the patellar tendon strain during surgery at 60° (r = -0.54, P < 0.05), 90° (r = -0.55, P < 0.05), or 135° of flexion (r = -0.65, P < 0.05) and postoperative knee flexion. Conclusions  The results indicated that subjects with high intraoperative patellar tendon strain during passive flexion of the knee had more restricted postoperative knee flexion. Therefore, the tightness of the knee extensor mechanism measured at total knee arthroplasty is a good predictor of maximum postoperative range of flexion.     

Synaptic transmission block by presynaptic injection of oligomeric amyloid beta

Early Alzheimer's disease (AD) pathophysiology is characterized by synaptic changes induced by degradation products of amyloid precursor protein (APP). The exact mechanisms of such modulation are unknown. Here, we report that nanomolar concentrations of intraaxonal oligomeric (o)Aβ42, but not oAβ40 or extracellular oAβ42, acutely inhibited synaptic transmission at the squid giant synapse. Further characterization of this phenotype demonstrated that presynaptic calcium currents were unaffected. However, electron microscopy experiments revealed diminished docked synaptic vesicles in oAβ42-microinjected terminals, without affecting clathrin-coated vesicles. The molecular events of this modulation involved casein kinase 2 and the synaptic vesicle rapid endocytosis pathway. These findings open the possibility of a new therapeutic target aimed at ameliorating synaptic dysfunction in AD.     

Thymic hyperplasia and thymus gland tumors: differentiation with chemical shift MR imaging

PURPOSE: To prospectively evaluate chemical shift magnetic resonance (MR) imaging for differentiating thymic hyperplasia from tumors of the thymus gland. MATERIALS AND METHODS: The institutional review board approved this study; informed consent was obtained and patient confidentiality was protected. The authors assessed 41 patients (17 male, 24 female; age range, 16-78 years) in whom thymic lesions were seen at chest computed tomography. Patients were assigned to a hyperplasia group (n=23) (18 patients with hyperplastic thymus associated with Graves disease and five with rebound thymic hyperplasia) and a tumor group (n=18) (seven patients with thymomas, four with invasive thymomas, five with thymic cancers, and two with malignant lymphomas). T2-weighted fast spin-echo and T1-weighted in-phase and opposed-phase MR images were obtained in all patients and visually assessed. A chemical shift ratio (CSR), determined by comparing the signal intensity of the thymus gland with that of the paraspinal muscle, was calculated for quantitative analysis. Mean CSRs for the patient groups and subgroups were analyzed by using Welch t and Newman-Keuls tests. P<.05 indicated a significant difference. RESULTS: The thymus gland had homogeneous signal intensity in all 23 patients in the hyperplasia group and in 12 of the 18 patients in the tumor group. The mean CSR (+/- standard deviation) was 0.614 +/- 0.130 in the hyperplasia group and 1.026 +/- 0.039 in the tumor group. Mean CSRs in the patients with a hyperplastic thymus and Graves disease, rebound thymic hyperplasia, thymoma, invasive thymoma, thymic cancer, and malignant lymphoma were 0.594 +/- 0.120, 0.688 +/- 0.154, 1.033 +/- 0.043, 1.036 +/- 0.040, 1.020 +/- 0.044, and 0.997 +/- 0.010, respectively. The difference in CSR between the hyperplasia and tumor groups was significant (P<.001). Mean CSRs in the hyperplasia subgroups were lower than those in the tumor subgroups (P<.001). All hyperplasia group patients had an apparent decrease in thymus gland signal intensity at chemical shift MR imaging; no tumor group patients had a decrease in thymus gland signal intensity. CONCLUSION: Chemical shift MR imaging can be used to differentiate thymic hyperplasia from thymic tumors.     

Bile duct hamartomas （von Mayenburg complexes） mimicking liver metastases from bile duct cancer： MRC findings

We present a case of a 72-year-old man with a common bile duct cancer, who was initially believed to have multiple liver metastases based on computed tomography findings, and in whom magnetic resonance cholangiography (MRC) revealed a diagnosis of bile duct hamartomas. At exploration for pancreaticoduodenectomy, liver palpation revealed disseminated nodules at the surface of the liver. These nodules showed gray-white nodular lesions of about 0.5 cm in diameter scattered on the surface of both liver lobes, which were looked like multiple liver metastases from bile duct cancer. Frozen section of the liver biopsy disclosed multiple bile ducts with slightly dilated lumens embedded in the collagenous stroma characteristics of multiple bile duct hamartomas (BDHs). Only two reports have described the MRC features of bile duct hamartomas. Of all imaging procedures, MRC provides the most relevant features for the imaging diagnosis of bile duct hamartomas.     

Myeloid/natural killer cell precursor acute leukemia with multiple subcutaneous nodules as the initial presentation: a case report and literature review

Myeloid/natural killer (NK) cell precursor acute leukemia is a rare neoplasm, which is characterized by high incidence of extramedullary infiltration, especially in the mediastinum and lymph nodes, an aggressive course and poor prognosis. As coexpressing myeloid and NK-cell antigens, myeloid/NK-cell precursor acute leukemia (MNKL) may pose diagnostic difficulty. Because the developmental pathway of normal NK cells is not well understood, neoplams of NK-cell origin are not clearly identified. To our knowledge, there have been only about 30 cases with this disease published previously. In the current paper, we present a case of a 21-year-old male patient whose initial presentation showed numerous subcutaneous nodules without bone marrow involvement. A diagnosis of MNKL was finally made by skin biopsy, bone marrow immunohistochemistry and immunophenotypic analysis. Although bone marrow achieved complete remission using DA chemotherapeutic regimen, the skin nodules did not regress. However, FLAG chemotherapeutic regimen, including fludarabine, cytarabine and G-CSF, was effective for both bone marrow and skin involvement. To the best of our knowledge, this study is the first to describe the effect of FLAG regimen for the treatment of this disease, indicating that it may be effective against the skin involvement of MNKL.     

Endoscopic radial incision and cutting method for refractory esophageal stricture after endoscopic submucosal dissection of superficial esophageal carcinoma

A 59‐year‐old woman and a 69‐year‐old man had esophageal strictures that were refractory to over 10 therapeutic attempts with endoscopic balloon dilation (EBD) after endoscopic submucosal dissections (ESD) for superficial esophageal carcinoma (SEC). The strictured lesions in both patients improved remarkably with a new endoscopic modality (endoscopic radial incision and cutting [ERIC]), which was carried out one to three times, and stricture recurrence was not noted throughout the follow‐up period. ERIC is a safe and efficient method for treating refractory strictures after EBD caused by ESD for SEC.