pH-dependent modulation of agonist interactions with [3H]-ketanserin-labelled S2 serotonin receptors

The effects of varying the pH on the properties of S2 serotonin receptors labelled by [3H]-ketanserin were examined. Between pH 7.0 and 8.2 the agonist affinities, as determined by competition experiments, increased dramatically. Serotonin, 5-methoxytryptamine, tryptamine, bufotenine and quipazine, demonstrated 15,16,8,6 and 5-fold increases in apparent affinity between pH 7.0 and 8.2. On the other hand the antagonists, ketanserin, cinanserin, and spiperone demonstrated little or no affinity changes between pH 7.0 and 8.2. The largest shift in affinity for an antagonist occurred with spiperone, which displayed a two-fold shift. Although changing pH is a rather non-specific manipulation, the selective affect on agonist interaction with S2 receptors indicates further investigation of this pH effect may aid in discovering the difference in receptor interactions between serotonin agonists and antagonists.

Initial detection of [3H]prazosin-labeled alpha 1-receptors in the porcine pituitary neurointermediate lobe

[3H]Prazosin binding to alpha 1-adrenergic receptors was investigated in homogenates of tissue from the porcine pituitary neurointermediate lobe. Potent alpha 1-adrenergic antagonists such as prazosin, WB-4101, and phentolamine displayed high potency in competing for [3H]prazosin specific binding in pituitary tissue. Epinephrine and norepinephrine were the only neurotransmitters which displayed high potency in competing for [3H]prazosin binding sites. There was a strong correlation in the pharmacological properties of the alpha 1 sites in pituitary tissue and the alpha 1 sites detected by [3H]prazosin in rat brain tissue. Alpha-adrenergic agonists demonstrated significantly higher potency for the alpha 1-receptor sites in pituitary tissue than in brain tissue preparations. The antagonist ketanserin demonstrated significantly higher potency at alpha 1 sites in pituitary tissue than in brain tissue. This latter observation has important implications for investigators attempting to use [3H]ketanserin as a selective serotonin receptor ligand in pituitary tissue. The results of this study represent the first demonstration of alpha 1-receptors in mammalian neurointermediate lobe tissue.

Properties of [3H]prazosin-labeled alpha 1-adrenergic receptors in rat brain and porcine neurointermediate lobe tissue

[3H]Prazosin binding to alpha 1 receptors in homogenates of rat prefrontal cortical tissue and porcine pituitary neurointermediate lobe tissue was investigated. Competition curves produced by coincubating adrenergic agonists and antagonists with 0.5 nM [3H]prazosin and tissue revealed some anomalous binding properties. In the brain and pituitary tissue, agonist competition curves produced "shallow" slopes, with Hill coefficients significantly lower than unity. The IC50 of the agonists epinephrine, norepinephrine, and clonidine for inhibition of 0.5 nM [3H]prazosin binding were significantly lower in the porcine pituitary than in the rat brain. Most antagonists, such as prazosin, chlorpromazine, and piperoxan, produced "steep" competition curves with Hill coefficients close to unity, with two notable exceptions. WB-4101 and phentolamine produced competition curves with Hill coefficients significantly less than unity in the rat brain preparation. Ketanserin, an antagonist, displayed a sevenfold higher affinity for the alpha 1 sites in the pituitary tissue than in the brain tissue. These anomalies in the binding results may indicate the presence of an endogenous modulatory factor affecting agonist and antagonist affinities for the alpha 1 receptor.

Modulation of brain S2 serotonin receptors by lithium, sodium and potassium chloride

The effect of LiCl, NaCl, and KCl on serotonin competition for 3H-ketanserin binding to S2 serotonin receptors in homogenates of rat prefrontal cortex were investigated. LiCl was the most potent of the ionic modulators in lowering the apparent affinity of serotonin for the S2 serotonin receptor. A threshold effect was noted at 12 mM LiCl (a 60% change in IC50); at 120 mM LiCl a nine-fold shift in the serotonin IC50 was noted. 120 mM NaCl or KCl demonstrated similar effects as 12 mM LiCl in reducing serotonin's apparent affinity. These results indicated that monovalent cations modulate S2 serotonin receptor affinity for serotonin and that lithium ion is more potent than sodium or potassium.

[3H]N-propylapomorphine and [3H]spiperone binding in brain indicate two states of the D2-dopamine receptor

[3H]N-propylapomorphine ([3H]NPA) a dopaminergic catecholamine derivative, labels a sub-set of D2-dopamine receptors in bovine caudate particulate preparation. [3H]Spiperone, a dopamine receptor antagonist, labels twice as many sites as [3H]NPA. Dopaminergic ergots and potent neuroleptics compete for both radioactive ligands with similar high affinities. Catecholamines and catecholamine derivatives compete more potently for [3H]NPA binding than for [3H]spiperone binding. Guanyl nucleotides reduce both [3H]NPA binding and the high affinity phase of catecholamine and catecholamine derivative competition for [3H]spiperone binding. These results are similar to binding results reported in studies of two-state receptors linked to adenylate cyclase such as the beta-adrenergic receptors. These observations indicate that the D2-dopamine receptor in the brain may exist in two states and may be inversely coupled to brain adenylate cyclase activity.

Mutagenic and toxic activity of environmental effluents from underground coal gasification experiments

Using bacterial bioassays, we have screened for the presence of mutagens and toxins in extracts from groundwater, and in tar from product gas, at the sites of two Lawrence Livermore National Laboratory (LLNL) in situ experiments: Hoe Creek II and Hoe Creek III. The sites exhibited different potential biological hazards, suggesting that different gasification processes may represent different human health concerns. We found that mutagens are present in groundwater, persist for at least 2 yr after gasification has been terminated, and show a change in activity with time-possibly in parallel with changes in chemical composition. Preliminary evidence suggests that the mutagens in groundwater are quinoline and aniline derivatives, while the toxins in groundwater may be phenolic compounds. In tar from the product gas, the organic bases and neutrals were found to be genotoxic in both bacterial and mammalian cells; the neutral compounds appear to be the major mutagenic health hazards. Neutral compounds constitute most of the tar (85-97 wt%) and were mutagenic in both the bacterial and mammalian cell assays. Tar in the gas stream may be a problem for the aboveground environment if gas escapes through fractures in the overburden. Because it is mutagenic and induces chromosomal damage to mammalian cells, the tar may represent a disposal problem as well. However, it is difficult to assess tar quantitatively as a health hazard because its mutagenic activity is low, possibly due to contaminants in the neutral fraction that act to suppress mutagenicity.

[Diagnosis of secondary tumors of the pancreas. Analysis of 13 cases]

The Authors report their experience of 13 cases of metastatic carcinoma of the pancreas, diagnosed over 350 pancreatic cancers examined by digestive angiography (4%). The rarity of this localization is emphasized and is affirmed that any organ may cause pancreatic metastasis (liver, bile ducts, oesofagus) although the kidney and the lung are more frequently the original sites. The pancreatic metastases were of different types but the multilocalized or the total forms don't prevail over the single ones. The angiographic modifications induced by these secondary lesions are evident but not characteristic and diagnosis only of pancreatic tumor can be evocated. Therefore digestive angiography is of high diagnostic value in this cases, although histologic examination is necessary to define the metastatic nature of these lesions.

A new technique for the treatment of esophageal bleeding in portal hypertension

A new method to operate on patients with bleeding due to portal hypertension is presented. It consists of splenectomy, devascularization of the gastric corpus, fundus and distal esophagus, resection-anastomosis of the lower esophagus, selective vagotomy with pyloromyotomy, and antireflux cardioplasty. All these procedures are carried out through a laparotomy; the esophageal resection-anastomosis is performed using the American circular EEA mechanical stapler. The method was used on 15 patients; there was one postoperative death. As regards the varices, early results were optimal. No encephalopathy was observed. Endoscopic dilatation of the anastomosis was required in four cases. No recurrence of hemorrhage has yet been observed.

Ultrastructural features in a case of ureteric malakoplakia

A case of urinary malakoplakia involving both ureters and the bladder is presented. Ultrastructural data relating to the ureteric lesion are illustrated. Pale, dark and intermediate cells were involved in the pathological process. Features common and specific for these three types of cell are described. Dark cells are thought to be of a histiocytic nature, while the others are of either histiocyte or urothelial origin. Cytoplasmic inclusions were abundant in all three types in the form of single-or multicentred multilamellar bodies. It was not clear whether these were the product of secretion or phagocytosis. Michaelis-Gutmann bodies, on the other hand, were found to be due to the deposition of needle-like crystals inside pre-existing multicentred multilamellar bodies. Pathogens could not be demonstrated for certain. It is felt, therefore, that the aetiology of malakoplakia must be considered as debatable. Biochemical and immunological research directed to the detection of a possible enzyme deficiency is suggested, along with further ultrastructural investigation of the histogenesis of the pale and intermediate cells.