Slow recovery of conduction velocity from use dependent inhibition induced by quinidine in guinea pig ventricular myocardium.

Study Objective: The aim was to investigate whether the use dependent effects of antiarrhythmic drugs on the Na+ current could be applied to explain their effects on impulse conduction.

Design: Trains of rapid stimuli were applied to guinea pig papillary muscles via an electrode in the presence of quinidine (20 and 60 mumol.litre-1), and the conduction velocity was determined from the time difference between two signals of the maximal rate of rise (dV/dtmax) of the action potentials at two separate sites.

DNA synthesis and scanning electron microscopic lesions in renal pelvic epithelium of rats treated with bladder cancer promoters.

The proliferation response of rat renal pelvic epithelium, lined by transitional epithelium, to administration of various bladder cancer promoters was investigated. In addition, prostaglandin E2 (PGE2), lipid peroxide (LPO), malondialdehyde (MDA) and cyclic adenosine 3':5'-monophosphate (cyclic AMP) levels were assessed in urine of rats given the non-promoter L-ascorbic acid (AsA) and the promoters sodium L-ascorbate (AsA-Na) or sodium bicarbonate (NaHCO3) for 4 or 8 weeks. DNA synthesis in the renal pelvic epithelium, as assessed by 5-bromo-2'-deoxyuridine (BrdU) incorporation, was increased in the groups given AsA-Na, an extremely high dose of sodium chloride (NaCl), tert-butylhydroquinone (TBHQ) or ethoxyquin (EQ).

[Burkitt's type ALL with numb chin syndrome as an initial manifestation].

A case of Burkitt's type ALL with numb chin syndrome as the initial manifestation is described. A 57-year-old Japanese male was admitted to our hospital in November 14, 1989 because of paresthesia at the chin and lower lip with diplopia and ptosis. Neurological examination revealed oculomotor paralysis of the right side and hypesthesia on the chin, lower lip and buccal mucous membrane.

Antiplatelet glycoprotein Ib monoclonal antibody (OP-F1) totally abolishes ristocetin-induced von Willebrand factor binding, but has minimal effect on the botrocetin-induced binding.

We describe here a new antiplatelet glycoprotein (GP) Ib monoclonal antibody (MoAb) designated OP-F1 (IgG1 kappa). Both OP-F1 and a well-characterized anti-GPIb MoAb, AP-1, totally abolished ristocetin-induced von Willebrand factor (vWF) binding to platelets and desialylated vWF binding to platelets at an IgG concentration of 2-8 micrograms/ml. AP-1 also blocked snake venom botrocetin-induced vWF binding at a similar IgG concentration, whereas OP-F1 had a minimal effect on botrocetin-induced binding.

Carcinogenicity of captafol in F344/DuCrj rats.

Captafol was administered at dietary levels of 0 (control), 750 and 1,500 parts per million (ppm) to groups of 50 male and 50 female F344/DuCrj rats for 104 weeks, and then all animals were maintained without captafol for a further 8 weeks, and killed in week 113. Renal cell carcinoma was found in eight of 50 male rats treated with 1,500 ppm and in one of 50 male rats treated with 750 ppm of captafol. The incidences of renal adenomas, including micro-adenomas, and basophilic altered cell tubules were significantly higher in both sexes treated with captafol than in controls, and the increases were apparently dose-dependent except that of adenomas in females.

Alteration of membrane oligosaccharides by castanospermine, an alpha glucosidase inhibitor, enhances immunoglobulin production in Staphylococcus aureus Cowan I-stimulated lymphocyte culture.

Castanospermine (CSP) inhibits alpha-glucosidase, which is involved in the initial step of N-linked oligosaccharide processing of secretory and membrane glycoproteins. In Staphylococcus aureus Cowan I (SAC)-stimulated human lymphocyte culture, CSP at a dose of 20 micrograms/ml caused a twofold increase in immunoglobulin G (IgG) release after 7 days. An initial 48-h exposure to CSP sufficed for this enhancing effect.

Demonstration of the heterogeneity of epitopes of the platelet-specific alloantigen, Baka.

It is well known that the platelet-specific alloantigen, Baka is carried on glycoprotein (GP) IIb, but little is known about the biochemical characteristics of its epitopes. To clarify the characteristics of the epitopes, we examined the interaction of four anti-Baka sera (Yam, Lin, Kl and MO) with their epitopes, either with or without modifications by sodium dodecyl sulphate (SDS) and/or neuraminidase. By immunoprecipitation, all four antisera bound to the intact GP IIb/IIIa complex from a Baka-positive subject.

Carcinogenicity study of methyl hesperidin in B6C3F1 mice.

A long-term carcinogenicity study of methyl hesperidin, a compound of the vitamin P group, was carried out in B6C3F1 mice receiving dietary concentrations of 0, 1.25 or 5%. Administration was continued for 96 wk and then the mice were maintained on basal diet for an additional 8 wk.

Autoimmune neutropenia with anti-neutrophil autoantibody associated with Sjögren's syndrome.

A 74-year-old man developed neutropenia in association with Sjögren's syndrome. The peripheral neutrophils in his blood decreased to 210/mm3 (total white blood cell count 2,100/mm3). Bone marrow examination showed an increase in the number of neutrophil precursors.

Structure-activity relations in promotion of rat urinary bladder carcinogenesis by phenolic antioxidants.

The urinary bladder tumor-promoting potentials of the phenolic antioxidants, 2-tert-butyl-4-methylphenol (TBMP), propylparaben, catechol, resorcinol and hydroquinone, which are structurally related to butylated hydroxyanisole (BHA), were investigated in 170 male F344 rats. The animals were initially given 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) as an initiator in their drinking water for 4 weeks.

[Evaluation of IgM anti human cytomegalovirus antibody].

An anti-human cytomegalovirus (HCMV) antibody in 330 sera from patients and normal subjects was examined by ELISA. The test results were compared with the results of CF test and there was 99.1% agreement.

Characteristics of histamine release from rat mast cells induced by a bracken toxin, braxin A1.

The effect of braxin A1, a new bracken glucoside, on histamine release from isolated rat peritoneal mast cells was studied. Braxin A1 caused the release of histamine in a dose-dependent manner; the release was slow and increased gradually with time, finally reaching a maximum release of 100%. The action of braxin A1 depended on the incubation temperature in the range from 4 degrees C to 49 degrees C, while it was almost abolished at 0 degree C.

Two human monoclonal antiplatelet autoantibodies established from patients with chronic idiopathic thrombocytopenic purpura.

Two human hybridomas secreting antiplatelet autoantibodies were established by somatic cell fusion using splenocytes from two patients with chronic idiopathic thrombocytopenic purpura (ITP). These monoclonal antibodies, HT7F and HT8C, were of the IgM isotype and reacted with autologous and allogeneic platelets fixed with paraformaldehyde (PFA). They also bound to fresh platelets.

Demonstration of platelet antigens that bind platelet-associated autoantibodies in chronic ITP by direct immunoprecipitation procedure.

Platelet antigens that bind platelet-associated autoantibodies in chronic idiopathic thrombocytopenic purpura (ITP) were demonstrated using a direct immunoprecipitation procedure. ITP platelets, with bound autoantibodies, were radiolabelled and solubilized, and then platelet antigen-antibody complexes adsorbed to protein A-bearing Staphylococcus aureus were analysed by 7.5% sodium dodecyl sulphate, polyacrylamide gel electrophoresis (SDS-PAGE).

Analyses of thrombocytopenia in idiopathic thrombocytopenic purpura-prone mice by platelet transfer experiments between (NZW x BXSB)F1 and normal mice.

Male (NZW x BXSB) F1 (W/B F1) mice, which develop lupus nephritis, myocardial infarction, and thrombocytopenia, showed reduced platelet lifespan (PLS) and increased platelet-associated antibody (PAA) values. There were statistically significant correlations between the increase in PAA values and either the reduction in PLS or the decrease in platelet counts. This and the results of platelet transfer experiments between old male W/B F1 mice and either female W/B F1 or normal BALB/c mice indicate that PAAs on the platelet surface play a crucial role in the destruction of platelets in W/B F1 mice.

Effect of pinacidil on the electrophysiological properties in guinea-pig papillary muscle and rabbit sino-atrial node.

The electrophysiological effect of the antihypertensive drug pinacidil has been examined in preparations of guinea-pig papillary muscle and rabbit sino-atrial node using a standard microelectrode method. In papillary muscle preparations, pinacidil (greater than 30 microM) shortened the action potential duration (APD), whereas it did not affect the maximum rate of rise (Vmax). Pinacidil (greater than 1 microM) also decreased APD of slow action potentials evoked by high K+ (27 mM) solution containing 0.

Glucocorticoid effects on myeloma cells in culture: correlation of growth inhibition with induction of glucocorticoid receptor messenger RNA.

Glucocorticoids are widely used for the treatment of multiple myeloma. To investigate the direct actions of glucocorticoids on myeloma cells, we have used three cell lines of human multiple myeloma, OPM-1, OPM-2, and RPMI 8226. When growth curves of these cells were examined, OPM-1 cells were resistant, while OPM-2 were sensitive to dexamethasone (DEX).

Dose response of N-butyl-N-(4-hydroxybutyl)nitrosamine on urinary bladder carcinogenesis in mutant ODS rats lacking L-ascorbic acid synthesizing ability.

With a daily intake of 250 ppm total ascorbic acid, ODS and F344 male rats were given 0.0125%, 0.025% or 0.

Lack of hepatotoxicity or promotion of enzyme-altered liver foci development in rats treated with harman or norharman.

The modifying effects of harman or norharman on liver carcinogenesis were investigated in male F344/DuCrj rats initially treated with N-nitrosodiethylamine (DEN). Two weeks after a single dose of DEN (200 mg/kg, intraperitoneally), rats were given harman or norharman at dietary levels of 1000 and 200 parts per million (ppm), or sodium phenobarbital (PB) at 500 ppm as a positive control, for 6 wk. At wk 3 following DEN administration, all animals were subjected to partial hepatectomy.

Acid treatment of platelets as a simple procedure for distinguishing platelet-specific antibodies from anti-HLA antibodies: comparison with chloroquine treatment.

The identification of antibodies to platelet-specific antigens is important for correctly diagnosing neonatal alloimmune thrombocytopenia, posttransfusion purpura and refractoriness due to platelet-specific antibodies. However, the serologic identification of these platelet-specific antibodies is complicated by the presence of anti-HLA antibodies. We examined and compared the diagnostic usefulness of acid-treated and chloroquine-treated platelets for the discrimination of platelet-specific antibodies from anti-HLA antibodies.

Bladder epithelial hyperplasia in F344 rats after intravesical instillation of the antitumor chemotherapeutic agents Adriamycin and mitomycin C.

The effects of intravesical instillation of the antineoplastic antibiotics, Adriamycin or mitomycin C, on the urinary bladder epithelium of female F344 rats were evaluated using a combined immunohistochemical and morphological approach. Four weeks treatment with Adriamycin or mitomycin C induced an increase of DNA synthesis and was associated with simple hyperplasia characterized by elevated nuclear cytoplasmic ratios, cytomegaly and pleomorphism. Under the scanning electron microscope (SEM), luminal cell surface alterations such as pleomorphic microvilli were observed.