Fast and slow blockades of the inward-rectifier K+ channel by external divalent cations in guinea-pig cardiac myocytes

The present patch-clamp study shows that external Mg²⁺, Ca²⁺ and Sr²⁺ decrease the unit amplitude of inward current through the inward-rectifier K⁺ channel in a concentration-dependent manner. Sr²⁺ produces a voltage-dependent flickering block as well, and the fractional electrical distance between the external orifice and the Sr²⁺ binding site () is 0.73. The decrease of unit amplitude is reversible and voltage independent while it does not increase the noise level on the open-channel current. Unit current decreased by Mg²⁺ or Ca²⁺ has a longer mean open time, which is inversely proportional to the unit amplitude. External Mg²⁺ does not decrease the amplitude of unit outward current. A surface potential shift, measured using voltage-dependent Cs⁺ block (=1.60), failed to explain the current decrease. Therefore, we conclude that (1) the external divalent cations cause an extremely fast channel block, which appears as a decreased amplitude of the unit current on the recording system; (2) the blocking site (fast site) is present near the external orifice of the channel, and it is separate from the blocking site (slow site) to which Cs⁺ and Sr²⁺ bind.     

An Epstein-Barr virus-producer line Akata: Establishment of the cell line and analysis of viral DNA

An Epstein-Barr virus (EBV)-producer line, designated Akata, was established from a Japanese patient with Burkitt's lymphoma. The Akata line possessed the Burkitt's-type chromosome translocation, t(8q-; 14q+), and was derived from the tumor cell. Akata cells produced a large quantity of transforming virus upon treatment of cells with anti-immunoglobulin antibodies (Takada, 1984). Southern blot analysis of viral DNA indicated that the Akata EBV is nondefective and more representative of wild-type viruses. Akata cells should be useful as a source of EBV.     

Fibrinogen stabilizes placental-maternal attachment during embryonic development in the mouse

In humans, maternal fibrinogen (Fg) is required to support pregnancies by maintaining hemostatic balance and stabilizing uteroplacental attachment at the fibrinoid layer found at the fetal-maternal junction. To examine relationships between low Fg levels and early fetal loss, a genetic model of afibrinogenemia was developed. Pregnant mice homozygous for a deletion of the Fg-gamma chain, which results in a total Fg deficiency state (FG(-/-)), aborted the fetuses at the equivalent gestational stage seen in humans. Results obtained from timed matings of FG(-/-) mice showed that vaginal bleeding was initiated as early as embryonic day (E)6 to 7, a critical stage for maternal-fetal vascular development. The condition of afibrinogenemia retarded embryo-placental development, and consistently led to abortion and maternal death at E9.75. Lack of Fg did not alter the extent or distribution pattern of other putative factors of embryo-placental attachment, including laminin, fibronectin, and Factor XIII, indicating that the presence of fibrin(ogen) is required to confer sufficient stability at the placental-decidual interface. The results of these studies demonstrate that maternal Fg plays a critical role in maintenance of pregnancy in mice, both by supporting proper development of fetal-maternal vascular communication and stabilization of embryo implantation.     

Determination of medullasin levels for the diagnosis of multiple sclerosis

Medullasin levels in granulocytes of patients with neurological diseases and healthy volunteers were determined by the enzyme immunoassay using mouse monoclonal antibodies against human medullasin and o-phenylenediamine-H2O2 as the detection system of the enzyme activity. One hundred twenty-one out of 159 patients with multiple sclerosis (76.1%) showed positive results (above means of normals + 2SD) in this test, while only 16.9% (24/142) of patients with non-inflammatory neurological diseases had positive results. This enzyme immunoassay method for medullasin is considered to be an useful paraclinical test for the diagnosis of multiple sclerosis.     

Study on CH50 levels in factor D-depleted serum

It is generally accepted that levels of serum whole complement activity (CH50) reflect the activities of complement (C) components of the classical C pathway (CP), since CH50 is assayed by use of sensitized sheep erythrocytes (EA). However, the alternative C pathway (AP) is considered to be also activated simultaneously in the process of activation of serum CP by EA. Thus, serum CH50 levels may possibly reflect not only CP but also AP activation in CH50 assay. We studied on the influence of AP activation during CH50 assay on CH50 levels, by comparison of CH50 levels in serum samples before and after treatment of factor D depletion. Polystyrene beads carrying polyanion, poly (2-acrylamide 2-methylpropane sulfonate) (PAMPS-beads), on the surface were prepared and used for preparation for factor D-depleted serum. After treatment of pooled normal human serum (NHS) with PAMPS-beads (2.5 mg/ml of serum), serum ACH50 level decreased to be undetectable, indicating that AP activation is prohibited in PAMPS-beads-treated serum. When isolated factor D was added to this PAMPS-beads-treated serum, ACH50 level recovered to that of before treatment. Immunoblot analysis revealed that factor D band observed in NHS disappeared completely after PAMPS-beads treatment. From these results, it is clear that factor-D deficient serum is prepared by PAMPS-beads treatment. Besides, since serum CH50 level was not decreased by PAMPS-beads treatment, it may be concluded that CH50 level is not affected by AP activation during CH50 assay.     

Association of Pasteurella multocida toxin with vimentin

To help understand the molecular mechanisms of Pasteurella multocida toxin (PMT) action, we searched for a cellular protein interacting with PMT. The ligand overlay assay revealed a 60-kDa cellular protein that binds to a region from the 840th to 985th amino acids of the toxin. This protein was identified as vimentin by peptide mass fingerprinting. The N-terminal head domain of vimentin was further found to be responsible for the binding to the toxin.     

A case of the esophageal candidiasis supposedly caused by rhinenchysis steroid chronic administration before sleep]

In general, steroid is mainly used as anti-inflammatory action in case of allergic diseases. As one of the side effects of inhalation steroid, a report is given below regarding buccal capsule/esophageal candidiasis. The patient came to the hospital with the chief complaint regarding passage dysphagia in the time of deglutition; pharyngitis and esophageal candidiasis were found by endoscopy of upper gastrointestinal tract.The interview after the endoscopy revealed that the patient, a 69-year-old female was diagnosed as chronic perennial allergic rhinitis a few years ago, and had been inhaling rhinenchysis Beclometasone dipropionate (BDP) before sleep every day for the past two years because using this collunarium seemed to mitigate the nasal obstruction and mucus during sleep. The patient did not report this fact before the endocsopy because she did not associate it with her subjective symptom. In this case, it was assumed that nebulized rhinenchysis BDP was accidentally swallowed to the pharynx and esophagus during sleep. As a treatment, rhinenchysis BDP was canceled and instead Azunol mouth washing (gargling/nasal douche) was used. No antifungal agent was used. In two weeks, the patient reported some improvement, and this was confirmed by reexamination of the upper gastrointestinal tract using endoscope in one month and a half. Pharyngitis was improved, and in the digital endoscopic assessment of esophageal candidiasis complicating inhaled steroid therapy the esophageal candidiasis became Grade I (mild grade). As for the later progress, the patient did not report any subjective symptoms such as nasal obstruction and dysphagia. In addition, the inflammation caused by candidiasis and found in the early examination was improved. The patient in this case was under treatment for thrombosis in the vein of lower extremity, but no complications such as diabetes mellitus or immune deficiency syndrome were observed. DISCUSSION: Esophageal candidiasis by chronic administration of inhalation of steroid before sleep for asthmatic patients has been reported. However, there has not been a report of esophageal candidiasis by chronic administration of rhinenchysis steroid before sleep for patients with allergic rhinitis. Similarly, in the case of the use of steroid in the form of collunarium before sleep, steroid stayed in the esophagus via the transendothelial nasal cavity, and that seemed to cause, in the long run, to develop esophageal candidiasis. CONCLUSIONS: One of the implications of the above case is that collunarium can go down, even when it is nebulized in the nasal cavity, to the esophagus via the nasal cavity to buccal capsule. This suggests the necessity for preventative measures in the case of chronic administration of steroid as follows. A. Blowing of the nose just after the use of collunarium B. Daily rinsing (gargling and nasal douche).     

Short half-lives of ataxia-associated aprataxin proteins in neuronal cells

Early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH)/ataxia with oculomotor apraxia type 1 (AOA1) is caused by mutations in the gene encoding aprataxin (APTX). Although several in vitro findings proposed that impaired enzymatic activities of APTX are responsible for EAOH/AOA1, potential instability of mutant proteins has also been suggested as the pathogenesis based on in vivo finding that mutant proteins are almost undetectable in EAOH/AOA1 tissues or cells. The present study aimed to experimentally prove instability of mutant proteins in neuronal cells, the cell type preferentially affected by this disease. Results of pulse-chase experiments demonstrated that all of the disease-associated mutants had extremely shorter half-lives than the WT. We further found that mutants were targeted for rapid proteasome-mediated degradation. These results help establish pathogenic and physiological protein characteristics of APTX in neuronal cells.     

IgG-KAPPA-PRODUCING PRIMARY PLASMACYTOMA OF THE THYROID GLAND WITH PREOPERATIVE SERUM M PROTEIN

A case of primary plasmacytoma of the thyroid gland which occurred in a 63-year-old woman is reported. Histologic and ultramicroscopic examination revealed that the excised thyroid tumor was plasmacytoma superimposed on lymphocytic thyroiditis. Immunohistological study showed that the tumor cells produced intracytoplasmic immunoglobulin (IgG-kappa). Electropho-retic and immunoelectrophoretic studies disclosed the presence of monoclonal immunoglobulin (IgG-kappa) in samples of the patient's serum which had been obtained preoperatively. After completion of irradiation therapy to the neck following tumor removal, the serum monoclonal immunoglobulin disappeared. The patient is currently alive and well without any evidence of the tumor three years after surgery.     

Clostridium perfringens foodborne outbreak due to braised chop suey supplied by chafing dish

On February 13, 2002, a public health center in Hiroshima Prefecture, Japan, was notified that many individuals living at the Japan Maritime Self-Defence Force base had symptoms resembling those of food poisoning. Self-administered questionnaires requesting information regarding meal consumption and symptoms were distributed to all 281 members at the base. A case of the illness was defined as a member who had had watery or mucousy stool, or loose stool with abdominal cramps, more than twice a day after consuming dinner on February 12. Control of the illness was defined as a member with no symptoms. The dinner on February 12 was significantly associated with the illness (Mantel-Haenszel odds ratio: 3.59, 95% confidence interval: 1.06-12.20). A case-control study showed that, among the food supplied at dinner on February 12, the braised chop suey was significantly associated with the illness (odds ratio: 12.30, 95% confidence interval: 1.90-521.00). The braised chop suey had been stored in a chafing dish. An environmental investigation indicated that Clostridium perfringens (C. perfringens) in the chafing dish proliferated under an inappropriate heat-retention temperature, and the contaminated braised chop suey could have caused the food poisoning. This study demonstrated that the recommended heat-retention temperature (over 65 degrees C) should be confirmed thoroughly.