A technique for transrectal ultrasonography of stallions during ejaculation

A technique was developed in which the accessory sex glands of stallions were visualized with transrectal ultrasonography during ejaculation. The technique was judged to be effective, since 10 of 11 stallions were trained to tolerate transrectal ultrasonography during ejaculation; they ejaculated during 195 of 200 attempts, and acceptable visualization of their accessory sex glands and excurrent ducts occurred during 97 of 195 ejaculations. Sixty-five percent (89 136 ) of the recordings were successful for stallions that weighed more than 300 kg, whereas 14% (8 59 ) of the recordings were successful for stallions weighing less than 300 kg. The 98 unsuccessful attempts were caused by inaccurate transducer placement due to the small size of the pelvic canal(33 98 ), excessive transducer movement due to stallion movement (32 98 ), indistinct ultrasound images (28 98 ) and human error (5 98 ). The technique was judged to be safe, since no stallions or personnel sustained serious injuries during 200 data collection attempts.     

Diagnostic significance of coexpression of intermediate filaments in fine needle aspirates of human tumors

A study was undertaken of the diagnostic significance of the coexpression of intermediate filaments in fine needle aspirates of human tumors. Three types of coexpression were found: (1) true coexpression, in which tumor cells simultaneously express more than one intermediate filament protein; (2) pseudocoexpression, in which various tumor cell types from histogenetically different parts of a complex tumor show different results; and (3) false coexpression, in which tumor cells with one or two types of intermediate filaments are present together with benign cells expressing a different filament type. True coexpression of vimentin and keratin was documented in renal cell carcinomas, endometrial carcinomas, certain thyroid carcinomas and Hürthle cell adenomas. Coexpression of keratin and neurofilaments was seen in Merkel cell carcinomas, and coexpression of desmin and vimentin was found in leiomyosarcomas. Keratin, vimentin and neurofilament expression was seen in medullary thyroid carcinomas, and keratin, vimentin and glial fibrillary acidic protein expression was observed in pleomorphic adenomas of the salivary gland. Pseudocoexpression was noted in synovial sarcoma, epithelioid sarcoma, benign cystosarcoma phyllodes of the breast, teratocarcinoma, malignant granular cell tumor, progonoma, Wilms' tumor and triton tumor. Sources of false coexpression are also discussed.     

Synergistic cytotoxic effect of tiazofurin and ribavirin in hepatoma cells

Tiazofurin, an anti-cancer drug, which induces remissions in human leukemia, and ribavirin, an anti-viral agent, bind at separate sites (NADH and IMP-XMP sites, respectively) on the target enzyme, IMP dehydrogenase. Now we show that the binding to IMP dehydrogenase of these drugs at two separate sites is translated into synergistic inhibition of de novo guanylate biosynthesis and synergistic toxicity in rat hepatoma 3924A cells. These results may be utilized in the chemotherapy of neoplastic diseases and in the treatment of hepatitis virus infection and hepatocellular carcinoma.     

Isolation of a domain of villin retaining calcium-dependent interaction with G-actin, but devoid of F-actin fragmenting activity

Villin is an F-actin binding protein located in the microfilament bundle of intestinal epithelial cell microvilli. Extensive in vitro proteolysis with Staphylococcus aureus V8 protease results in the production of a stable domain (apparent Mr 44000) which can be isolated due to its Ca2+-dependent interaction with G-actin bound to immobilized DNase-I, the standard procedure for the purification of villin. This 44-kDa fragment retains a single Ca2+ binding site with an apparent Kd = 2 X 10(-6) M, binds to G-actin, and inhibits the rate of actin polymerization. However, the 44-kDa domain does not shown any Ca2+-activated severing activity nor does it compete with villin for F-actin binding. These results suggest that villin contains three domains: headpiece containing an F-actin binding site, 44-kDa fragment containing a G-actin binding site, and an amino-terminal fragment responsible for the Ca2+-dependent severing activity.     

Ethanol selectively affects Na+-gradient dependent intestinal transport systems

Moderate concentrations of ethanol reduce the velocity of uptake of three representative Na+-symport systems (D-glucose, L-alanine, L-ascorbate), whether electrogenic (the first two) or electroneutral (L-ascorbate). This 'inhibition' is observed only if these transport systems are tested in the presence of an initial Na+ gradient (out greater than in); no inhibition is found in tracer-equilibrium exchange measurements. A representative Na+-independent system (D-fructose) is not inhibited by ethanol. 'Passive diffusion' (measured as uptake of L-glucose) is increased somewhat by alcohol. All these observations can be rationalized [as suggested by Tillotson et al. (1981) Arch. Biochem. Biophys. 207, 360-370] by an effect of ethanol on passive diffusion, which leads to a faster collapse of the Na+ gradient, with the resulting reduction of the uptake velocities of Na+-dependent transport systems when tested with the added driving force of an Na+ out----in gradient.     

Author index to volume 200

Biochemical and partial sequence data reveal the two-domain structure of p36. A loose structure of some 30 residues at the amino-terminus contains the phosphorylatable tyrosine and the binding site for the p11 regulatory chain. The following p33 domain retains the lipid-binding site as well as the Ca2+ site which influences the spectral properties of the single tryptophan and one tyrosine. The combined sequence data covering about 25% of the molecule identify p36 as a unique polypeptide.     

Reconstruction of a type-B configuration monkey Sertoli cell: size, shape, and configurational and specialized cell-to-cell relationships

A model of a stage-V monkey Sertoli cell was reconstructed from electron micrographs taken of semiserial sections. The configuration (type-B) was one in which spermatids were positioned near the lumen, their heads occupying shallow cylindrical recesses at the apical portion of the Sertoli cell. The cell volume was calculated to be 4,100 micron3, the surface area 2,400.68 micron2, and the surface-to-volume ratio 0.58:1. The reconstructed cell extended from the basal lamina to the tubular lumen and was generally of the tall columnar type although its surface contour was highly irregular. The dimensions of the cell [centripetal (68.46 micron), circumferential (18.40 micron), and longitudinal (21.63 micron)] were determined and cell surfaces designated. Relative and absolute surface areas of the reconstructed cell which faced other Sertoli cells, germ cells, basal lamina, and tubular lumen were calculated. Junctions and surface specializations were enumerated, catalogued, and depicted on diagrams of the cell surface. Where appropriate, type-A rat and type-B monkey Sertoli cells were compared and discussed. Morphometry was utilized to analyze the relative surface areas of germ cells adjoining the reconstructed cell to determine the percentage of their surface facing cellular and acellular elements, and these data were compared to data obtained for the rat.     

The interaction of phosphate with the purple acid phosphatase from beef spleen: evidence that phosphate binding is accompanied by oxidation of the iron chromophore

Reaction of the reduced (pink) form of the purple acid phosphatase from beef spleen with excess phosphate at pH 5.0, monitored by optical and low temperature EPR spectroscopy and by measurement of enzymatic activity, results in parallel loss of activity and oxidation of the iron chromophore. Colorimetric and radiochemical (32P) experiments indicate the presence of one mole of tightly bound phosphate in the oxidized (purple) form of the enzyme; this phosphate is released upon reduction. Acid hydrolysis of 32P-phosphate-containing enzyme, followed by high voltage paper electrophoresis, gave no evidence for significant amounts of acid-stable phosphoamino acids.