Hypoxic contraction of isolated canine coronary artery. Mediation by potassium-dependent exocytosis of norepinephrine

Effects of hypoxia on arterial tone, efflux of potassium, and efflux of norepinephrine were monitored for isolated canine coronary arteries labeled with radioactive potassium (42K) and norepinephrine (3HNE). Hypoxia elicited transient relaxation and subsequent sustained contraction accompanied by marked increases in the effluxes of 42K and 3HNE. After sympathetic nerve injury with 6-hydroxydopamine or cold storage, arteries responded to hypoxia with sustained relaxation. Sustained relaxation occurred also after pretreatment with L-propranolol, but not with D-propranolol or phentolamine. Inhibition of hypoxic contraction by L-propranolol did not alter 42K or 3HNE efflux. Colchicine, an inhibitor of the exocytosis of NE, suppressed hypoxic 3HNE efflux and contraction, but not 42K efflux. Proadifen inhibited 42K and 3HNE efflux as well as contraction. During proadifen-inhibited 42K efflux, exogenous K+ augmented overflow of 3HNE, indicating that proadifen relaxed the hypoxic artery primarily by inhibiting K+-dependent exocytosis of NE. The ratio of NE to dopamine beta-hydroxylase activity was similar in effluents from oxygenated arteries exposed to elevated K+ concentrations and in effluents from hypoxic arteries. Thus, hypoxia evoked exocytotic release of norepinephrine which promoted contraction by a beta-adrenergic mechanism.     

Comparison of urinary excretion of UV-absorbing constituents in healthy subjects and patients with rheumatoid arthritis using analytical isotachophoresis

Analytical isotachophoresis has been applied to the separation of urinary constituents in healthy controls and patients with rheumatoid and osteoarthritis. Various methods of comparing isotachograms have been investigated. Significant differences have been demonstrated between the pattern of UV-absorbing components in patients with rheumatoid arthritis and healthy subjects.     

Second examination in meat inspection (author's transl)

A second examination at the expense of the party adjudged to be in error is based on Section 13 of the Meat Inspection Act in the Netherlands, which has been elaborated in Sections 51 and 51a of the Meat Inspection Order. The procedure to be adopted by the second veterinary-surgeon inspector, however, has not been stipulated. The need for clear instructions is stressed. The present paper was designed to promote objectivity and uniformity in second inspections to provide legal security for the owner of the slaughtered animal as well as for the first veterinary-surgeon inspector.     

Fluoride stimulation of the rat parathyroid gland: an ultrastructural study

The parathyroid glands of rats given 150 ppm fluoride in the drinking water for 10 weeks are evaluated ultrastructurally and compared to the parathyroid glands of untreated rats. As a result of fluoride ingestion, the majority of the parathyroid cells are dark chief cells, indicating that these cells are in the active stages of the secretory cycle. More significantly, in the fluoride-treated rats, the cytoplasmic organelles of the dark chief cells are even more developed that those seen in the dark chief cells of untreated rats. The dark cells contain an electron-dense cytoplasm with abundant lamellar arrays of rough endoplasmic reticulum, spiral aggregations of free ribosomes, multiple dilated Golgi complexes, and increased numbers of secretory granules. The cells are at a minimum dimension with maximum tortuosity of the plasma membranes; and, as a result, large intercellular spaces are often seen between contiguous cells. Based on these observations, it is suggested that, in the fluoride-treated rat, a type of secondary hyperparathyroidism develops resulting in an increase in the organelles involved in protein synthesis and secretion.     

The family history component of cancer genetic risk counseling

This study evaluated effective resistances on the ventricular surfaces of arterially-perfused rabbit hearts. Effective resistances were determined with a four-electrode array that was parallel or perpendicular to epicardial fibers. Resistance along or across epicardial fibers was determined by applying current to the epicardium with two parallel line electrodes and measuring potentials in the region between the electrodes. Computer simulations were performed to gain insight into the distribution of current in the ventricular wall. The effective resistances were not different along versus across fibers. Simulations showed that transmural rotation of fibers causes current to be distributed differently when the electrode is oriented perpendicular versus parallel to epicardial fibers. When the array is oriented so that epicardial current is across fibers, the fraction of current that flows transmurally and along the deeper fibers increases while the fraction of current that flows epicardially decreases. This introduces isotropy of the effective resistance. Thus, in contrast to isolated cardiac fibers, the ventricular epicardium exhibits isotropic effective resistance due to transmural rotation of fibers. The rotation and isotropic resistance may be important for cardiac electrical behavior and effects of electrical current in the ventricles.     

Crystal structure studies on plate/shelf like disodium ditungstate

The structure of plate/shelf like disodium ditungstate (Na₂W₂O₇) synthesized by new method in the process of ultrasonic spray pyrolysis using acidified aqueous solutions of tungsten (VI) oxide clusters as a precursor was refined down to the R-factor of 8.9 %. X-ray diffraction analysis undoubtedly confirmed formation of orthorhombic Na₂W₂O₇ and refinement of the diffraction data showed that Na₂W₂O₇ powder belongs to the base-centred orthorhombic type of structure with 64 space group, Cmca. The structure of Na₂W₂O₇ can be described as infinite chains formed from tetrahedral (WO₄) and octahedral (WO₆) building units joined together. It was found that the basic units of the precursor complexes exist in the structure of Na₂W₂O₇. Scanning electron microscopy confirmed formation of plate/shelf like Na₂W₂O₇ particles with an average thickness of about 1.2 μm.