Toxicodynamics of tumour promoters of mouse skin III. Specific binding of the tumour promoter thapsigargin as measured by the cold-acetone filter assay

Summary A method is described for measuring rapid, specific, and saturable binding of the skin irritant and tumour-promoting secretagogue thapsigargin (sesquiterpene lactone) to the microsomal fraction from mouse brain. Employing the tritium-labelled compound its apparent dissociation constant,K _d, and the maximal amount of bindingB _max are shown to be 9.8 nM and 1.9 pmol/mg protein respectively. Such aK _d for thapsigargin is similar to (a) its IC₅₀ value for inhibiting Ca²⁺ uptake in the microsomal fraction from rat brain and (b) its EC₅₀ values for inducing a rise in the cytoplasmic Ca²⁺ concentration of human platelets and histamine release from rat peritoneal mast cells. A positive correlation is found between the binding affinities of thapsigargin, thapsitranstagin, and trilobolide, their potencies as secretagogues and their lipophilicities. This correlation does not extend to the skin-irritant activities of the compounds thus emphasizing that their mechanism of action is unlike that of 12-O-tetradecanoylphorbol 13-acetate.Abbreviations Tg thapsigargin - Tt thapsitranstagin - Tr trilobolide - TPA 12-O-tetradecanoylphorbol 13-acetate - K _i,K _d apparent inhibition and dissociation constants - ID ₅₀ ⁵ irritant dose for 50% response after 5 h For II see Hergenhahn et al. 1991     

Arterial anatomy and arteriographic diagnosis of arteriogenic impotence

One hundred twenty-six bilateral selective arteriographic examinations of the iliopudendal vascular tree were performed after comprehensive multidisciplinary evaluation in patients with chronic erectile dysfunction. Best imaging results were obtained by performing the arteriography under epidural anesthesia after intracavernous injection of a vasoactive drug combination. The arteriography is mandatory prior to revascularization procedures. It is further indicated in primary erectile dysfunction and posttraumatic erectile failure. The importance of cavernosography and selective arteriography in primary erectile dysfunction is stressed. Increasing knowledge about the influence of vasoactive drugs on penile hemodynamics has led to its application in diagnosis and therapy of erectile dysfunction. Pharmacocovernosography, Doppler-ultrasound of penile arteries after intracavernous injection of a vasoactive drug combination, and pharmacoarteriography are refined techniques to prove a vascular etiology of erectile dysfunction. The results of the morphologic studies of the vascular system are correlated with functional testing of erectile capacity by intracavernous application of a papaverinephentolamine drug combination.     

Synthesis,Decarboxylation, and Nitrosation of 1-Acyl-2-pyrrolidone-3-carboxylic Acids: A Convenient Novel Entry to 2,3-Dioxopyrrolidine Derivatives

Esters 1 of 1-acyl-2-pyrrolidone-3-carboxylic acids 2 were hydrolized to 2 with acetic acid/HCl at 60–70°C. Reaction of 1a with formic acid/HCl at 60–75°C led to (not isolated) 2a which began to decarboxylate to 3a during the conversion of 1a to 2a even at this low temp. Decarboxylation of 2c-f was accomplished at 160°C without solvent. Decarboxylative nitrosation of 2c-f yielded the oximes 4c-f of 1-acyl-2,3-dioxopyrrolidines. Treatment of 4f with magic methyl provided the enol ether 5f of the respective dioxopyrrolidine.     

α galnac is essential for recognition of EXO-1 epithelial antigen by mouse monoclonal antibody Pa-G-14

Mouse monoclonal antibody Pa-G-14 detects Exo-1, an antigen whose expression is regulated in the processes of epithelial-cell differentiation and transformation. The epitope recognized by Pa-G-14 is present both in glycosphingolipids and in mucin glycoproteins. To characterize the specificity of Pa-G-14, immuno-thin-layer chromatography, biochemical, and enzymatic treatment of glycosphingolipid extracts from human pancreas were used. The antibody bound to all blood-group-A substances; αGaINAc, but not fucose, was essential for reactivity. In ELISA, Pa-G-14 also reacted with ovine and bovine submaxillary mucins but not with porcine submaxillary mucin. Binding to ovine submaxillary mucin was resistant to neuraminidase treatment. In solid-phase absorption assays on synthetic carbohydrate structures, Pa-G-14 recognized broadly blood group A, Tn and sialyl-Tn. Using immuno-electron-microscopic techniques, reactivity with all Golgi cisternae and mucin droplets of mucous cells in ovine submaxillary gland was demonstrated. All these assays indicate that Pa-G-14 shows a novel specificity, since it binds blood group A, Tn and sialyl-Tn, the common structural feature of these epitopes being the presence of a terminal αGalNAc sugar unit.     

Adsorption of technetium-99m tetrofosmin and technetium-99m furifosmin on plastic syringes

Some groups have reported that adsorption of radiopharmaceuticals on disposable plastic syringes can reach levels of almost 50%. This high loss of radioactivity stimulated us to carry out similar studies. Our measurements were done in combination with patient studies. Therefore, we used 2-ml syringes, all of the same brand. The radioactivity in the syringe was measured immediately before and after injection. a total of 500–600 MBq technetium-99m labelled tetrofosmin or technetium-99m furifosmin was administered to 48 patients using four different injection techniques (n = 6 for each technique with each tracer): with needles, 1 min blood incubation at 22°C, 10 or 30 min after preparation of the tracer; with butterflies, 1 min blood incubation at 22°C, 10 or 30 min after preparation of the tracer. Neither in syringes nor in needles or butterflies did more than 7% of the initial radioactivity remain. The entire residual activity in syringe plus needle or syringe plus butterfly together never exceeded the 9% limit. Furthermore, in a pilot study we measured the remaining radioactivity in the vial; here, too, we found no more than 14% of total radioactivity. These findings indicate that total retention of radioactivity during elution and application of ^99mTc-tetrofosmin and ^99mTc-furifosmin with material used in our setting does not approach relevant amounts. Received 6 May and in revised form 19 May 1998     

Fibromuseular dysplasia of the internal carotid artery in a child with alpha-1-antitrypsin deficiency

Fibromuseular dysplasia (FMD) is a non-inflammatory segmental arteriopathy of unknown origin. Most often the renal arteries are affected, however, also mesenteric, lumbar, vertebral, or carotid arteries may be Involved. FMD has frequently been reported as a cause of stroke in adults, but very rarely in children. We report the case of an 11-year-old boy who presented with an ischaemic infarction in the anterior part of the territory of the left middle cerebral artery. Angiography demonstrated a'string of beads'lesion suggestive of FMD causing occlusion at the origin of the middle artery. Laboratory analyses revealed the protease inhibitor (Pi) phenotype SZ (PiSZ) of alpha-1-antitrypsin deficiency as well as decreased antioxidants and signs of enhanced lipid peroxidation. Such an imbalance may be associated with diminished resistance to oxidation, possibly causing direct cellular and tissue injury. Whether alpha-1-antitrypsin deficiency and an impaired status of antioxidants, as seen in our patient, might play a role in the pathogenesis of FMD is presently unclear.