Extracellular adenosine 5'-triphosphate induces Ca2+ efflux from freshly isolated adult rat cardiomyocytes: possible involvement of Na+/Ca2+ exchange mechanism

In the present study, we examined the effect of extracellular adenosine 5'-triphosphate (ATP) on Ca2+ efflux from freshly isolated adult rat cardiomyocytes. ATP at 1 mM caused a release of 3.6+/-0.08% of the total cellular content. The 45Ca2+ efflux from the cells was also stimulated by adenosine-5'-O-(3-thiotriphosphate) (ATP-gamma s), alpha, beta-methylene-ATP and adenosine 5'-diphosphate (ADP), but not by adenosine 5'-monophosphate (AMP) or adenosine. The effect of ATP was inhibited by a known purinergic P2-receptor antagonist, but not by a P1-receptor antagonist. From these results, it is conceivable that the effect of ATP on Ca2+ efflux from cardiomyocytes is mediated through P2-purinoceptors. It was also observed that ATP caused a rise in [Ca2+]i to almost 200 nM. The ATP-stimulated 45Ca2+ efflux was not affected by removal of extracellular Ca2+, but was dependent on the presence of extracellular Na+. Moreover, ATP caused a 22Na+ influx into the cells of about 2.0-fold over the basal value. These result suggest that ATP stimulates extracellular Na+-dependent 45Ca2+ efflux from freshly isolated adult rat cardiomyocytes, probably through its stimulatory effect on plasma membrane P2-purinoceptors which may couple to Na+/Ca2+ exchange.     

SURFACE MODIFICATION ON OXIDE SUPERCONDUCTOR USING C02 LASER

Powder-sintered oxide superconductor does not allow the flow of superconducting current uniformly and the flow is concentrated on the surface. Further, it is poor in mechanical strength. Thus, properties of oxide superconductor ere so sensitive to their surface condition that some substantial modifications of the material are necessary. Powder sintered superconductor surfaces have been modified using C0₂ laser irradiation, The mechanical strength almost doubled and the current density was about 25 times greater after irradiation. The modified layer showed not only the elimination of many pores among grain boundaries but also preferred orientation of crystal grains.     

Characteristics of cefdinir uptake by rabbit small intestinal brush-border membrane vesicles

PURPOSE: To search for changes in the presence and distribution of the cell-adhesion-related HNK-1 carbohydrate epitope after cataract extraction. METHODS: Twenty-five pseudophakic and two aphakic human autopsy eyes and, for comparison, one anterior subcapsular cataract obtained at surgery were studied with monoclonal antibodies (MAbs) HNK-1 and NC-1 to the HNK-1 epitope using the avidin-biotinylated peroxidase complex method. RESULTS: MAbs to the HNK-1 epitope constantly immunolabelled the inner connective tissue layer of the ciliary body in all pseudophakic and aphakic eyes studied. The distribution of the immunoreaction was similar to that reported for normal eyes. They also labelled the extracellular matrix in each of 18 plaques of secondary cataract on the posterior capsule, in each of 13 plaques at the rim of the capsular bag, and in the anterior subcapsular cataract. Bladder cells in each of 16 Soemmering's rings remained unlabelled. CONCLUSION: The distribution of the HNK-1 epitope in the ciliary body does not appreciably change after cataract extraction, although the accommodative demand of the eye is altered. Its presence in an anterior subcapsular cataract suggests that the epitope may be locally produced by lens epithelial cells also in secondary cataract. The epitope is associated with cell adhesion and migration, both of which may play a role in the pathogenesis of secondary cataract.     

An investigation into the relationship between processing,structure and properties for high-modulus PBO fibres: part 3: analysis of fibre microstructure using transmission electron microscopy

A detailed morphological study of the microstructure of poly(p-phenylene benzobisoxazole) (PBO) fibres (HM and HM+) and a polypyridobisimidazole (PIPD) (HT) fibre has been undertaken using transmission electron microscopy. Both PBO and PIPD fibres are composed of rigid-rod polymers having p-phenylene rings in the molecular backbone and show high modulus (280–360 GPa) and high strength (4–6 GPa). It is found that the PBO HM+ fibre has the highest degree of molecular orientation of the three fibres and the longest crystal length along the fibre axis, while the PIPD fibre shows a lower degree of orientation and a shorter crystal length than the PBO fibres. To understand the effect of crystalline size and fine structure of the fibres upon mechanical properties, dark-field and high-resolution lattice images were obtained and analysed in detail.     

The effect of pituitary adenylate cyclase activating polypeptide (PACAP) on amylase secretion from guinea pig pancreatic acini

Beta-lactamase production is one of the major mechanisms of resistance amongst bacteria especially the enteric bacilli. The purpose of this study is to assess the in-vitro activity of Sulperazon, a combination of cefoperazone and an irreversible beta-lactamase inhibitor, sulbactam, against the cefoperazone resistant isolates of aerobic gram-negative bacilli. A total of 92 such strains were tested. It was found that at a concentration of < or = 8 mg/l of sulbactam added to cefoperazone 82% of Klebsiella spp, 100% of E. coli, 100% of Enterobacter spp, 33% of Pseudomonas aeruginosa, 67% of Pseudomonas spp and 62% of Acinetobacter spp that were resistant to cefoperazone alone were susceptible to the combination. Hence it is concluded that the addition of sulbactam to cefoperazone does expand the spectrum of the in-vitro activity of cefoperazone.     

Efficacy of exogenous fibronectin in wound healing in malnourished rats

BACKGROUND/PURPOSE: Fibronectin (FN) plays an important role in fibrin matrix formation during the wound healing process. The authors investigated whether exogenous FN increases the bursting strength (BS) of surgical wounds in malnourished rats. METHODS: Ninety rats were grouped according to three nutritional conditions (n = 30 in each group). All animals underwent a transverse celiotomy after 3 weeks of feeding, and FN (2 mg/body/day) was given postoperatively to 15 rats in each of the three groups. Wound BS was measured on postoperative days (PODs) 3, 5, and 7 after removal of the sutures. RESULTS: BS in normally nourished rats (group N; 142.6+/-23.4 mmHg) was significantly higher than that in protein malnourished rats (group PM, 110.2+/-11.2 mm Hg) and protein/ calorie (Cal)-malnourished rats (group PCM, 76.5+/-10.7 mm Hg) on POD 7 (P<.01). However, BS values for groups PM + FN (147.0+/-21.1 mmHg) and PCM + FN (115.1+/-28.9 mm Hg) were intensified significantly in comparison with groups PM and PCM (P<.01). Plasma FN levels in rats of the three FN nontreated groups were similarly decreased on POD 3 or 5, but returned to the preoperative level on POD 7, whereas those for the other three FN-treated groups increased after POD 3. CONCLUSION: Intravenous administration of FN might strengthen the weakened wounds of malnourished animals.     

Synthesis and antihypertensive activity of 4-(diazabicyclo[4.1.0]-heptenyloxy)benzopyran derivatives and their analogues

A series of 3,4-dihydro-3-hydroxy-4-[(5-oxo-3,4-diazabicyclo[4.1.0]hept- 2-en-2-yl)oxy]-2H-1-benzopyrans and their analogues were synthesized and evaluated on potassium channel opening and hypotensive activities. Compound (-)-13B with a (4-methyl-5-oxo-3,4-diazabicyclo[4.1.0]hept-2-en-2-yl)oxy group for the 4-position of the benzopyran ring was 3 times as potent as EMD 57283 (II), the lead compound, in hypotensive activity. The results would demonstrate that 5-oxo-3,4-diazabicyclo[4.1.0]hept-2-en-2-yloxy moieties are effective as the substituents at the 4-position of benzopyran-type potassium channel openers.     

Intractable gastrointestinal bleeding caused by pancreatic arteriovenous malformation: successful treatment with transjugular intrahepatic portosystemic shunt

A case of childhood cutaneous mucinosis is described. This is a clinical condition that is rarely seen and has only recently been included in the group of primary mucinosis.     

Anesthetic management for a patient with pheochromocytoma using magnesium sulfate and epidural block

A 54-year-old woman with pheochromocytoma was anesthetized using magnesium sulfate infusion. Anesthesia was induced with thiopental and fentanyl, and maintained with 0.5% sevoflurane in nitrous oxide/oxygen and 60 mg.hr-1 of epidurally infused lidocaine. Muscle relaxation was achieved with intermittent administration of vecuronium under neuromuscular monitoring. Magnesium 2 g was infused prior to the tracheal intubation and followed by continuous infusion of 2 g.hr-1. These anesthetic techniques made hemodynamic state stable, and no additional vasoactive agents were needed. However, the infusion rate of magnesium was reduced to a half because of PQ interval prolongation. Magnesium is believed to be useful for anesthetic management for patients with pheochromocytoma, but the proper dose and the way of administration should be further investigated for their safe clinical use.