A case of von Recklinghausen's disease associated with pheochromocytoma and papillary carcinoma of the thyroid gland

A 58-year-old woman was admitted to our hospital complaining of headache, dizziness and intermittent elevation of blood pressure. Multiple café-au-lait spots and neurofibromas had appeared on the back and the limbs since the age of 30 years. At the age of 54 years she underwent total thyroidectomy because of papillary carcinoma of the thyroid gland. On admission, the levels of plasma norepinephrine and epinephrine, urinary norepinephrine and normetanephrine were all within the normal range. However, urinary excretion of metanephrine was markedly increased to 1.49 +/- 0.45 (Mean +/- SD) mg/day and that of epinephrine was also slightly increased. The computed tomographic scans of the abdomen and the scintigraphy with 131I-metaiodobenzylguanidine revealed a tumor mass in the region of the right adrenal gland. The tumor was histologically confirmed to be pheochromocytoma at the operation. In her family history, her mother and one of her two sisters had von Recklinghausen's disease and another sister suffered from follicular carcinoma of the thyroid gland. As far as we know, this paper is the first report of a patient with von Recklinghausen's disease associated with both pheochromocytoma and non-medullary carcinoma of the thyroid gland, and her family.     

In vitro studies on some parameters of the binding of the rat hemopexin--heme complex with the hepatic membrane receptor

The binding of [125I]Hpx--heme with the rat hepatic plasma membrane receptor was studied at 37 degrees C as well as different parameters such as plasma membrane concentration, calcium dependence, optimal pH and specific binding. A Scatchard plot revealed the existence of one binding for [125I]Hpx--heme on the isolated liver plasma membrane with a Kd = 3.2 X 10(-8) M.     

O-acetylation and de-O-acetylation of sialic acids. O-acetylation of sialic acids in the rat liver Golgi apparatus involves an acetyl intermediate and essential histidine and lysine residues--a transmembrane reaction?

Isolated intact rat liver Golgi vesicles utilize [acetyl-3H]coenzyme A to add 3H-O-acetyl esters to sialic acids of internally facing endogenous glycoproteins. During this reaction, [3H]acetate also accumulates in the vesicles, even though the vesicles are impermeant to free acetate. On the other hand, entry of intact AcCoA into the lumen of the vesicles could not be demonstrated, and permeabilization of the vesicles did not alter the reaction substantially (Diaz, S., Higa, H. H., Hayes, B. K., and Varki, A. (1989) J. Biol. Chem. 264, 19416-19426). When vesicles prelabeled with [acetyl-3H] coenzyme A are permeabilized with saponin, we can demonstrate a [3H]acetyl intermediate in the membrane that can transfer label to the 7- and 9-positions of exogenously added free N-acetylneuraminic acid but not to glucuronic acid or CMP-N-acetylneuraminic acid. This labeled acetyl intermediate represents a significant portion of the radioactivity incorporated into the membranes during the initial incubation and cannot be accounted for by nonspecifically "trapped" acetyl-CoA in the permeabilized vesicles. There was no evidence for involvement of acetylcarnitine or acetyl phosphate as an intermediate. The overall acetylation reaction appears to involve two steps. The first step (utilization of exogenous acetyl-CoA to form the acetyl intermediate) is inhibited by coenzyme A-SH (apparent Ki = 24-29 microM), whereas the second (transfer from the acetyl intermediate to sialic acid) is not affected by millimolar concentrations of the nucleotide. Studies with amino acid-modifying reagents indicate that 1 or more histidine residues are involved in the first step of the acetylation reaction. Diethylpyrocarbonate (which can react with both nonsubstituted and singly acetylated histidine residues) also blocks the second reaction, indicating that the acetyl intermediate on both sides of the membrane involves histidine residue(s). Taken together with data presented in the preceding paper, these results indicate that the acetylation of sialic acids in Golgi vesicles may occur by a transmembrane reaction, similar to that described for the acetylation of glucosamine in lysosomes (Bame, K. J., and Rome, L. H. (1985) J. Biol. Chem. 260, 11293-11299). However, several features of this Golgi reaction distinguish it from the lysosomal one, including the nature and kinetics of the reaction and the additional involvement of an essential lysine residue. The accumulation of free acetate in the lumen of the vesicles during the reaction may occur by abortive acetylation (viz. transfer of label from the acetyl intermediate to water). It is not clear if this is an artifact that occurs only in the in vitro reaction.     

Volume regulation by flounder red blood cells in anisotonic media

The nucleated high K, low Na red blood cells of the winter flounder demonstrated a volume regulatory response subsequent to osmotic swelling or shrinkage. During volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation after osmotic swelling is referred to as regulatory volume decrease (RVD) and was characterized by net K and water loss. Since the electrochemical gradient for K is directed out of the cell there is no need to invoke active processes to explain RVD. When osmotically shrunken, the flounder erythrocyte demonstrated a regulatory volume increase (RVI) back toward control cell volume. The water movements characteristic of RVI were a consequence of net cellular NaCl and KCl uptake with Na accounting for 75 percent of the increase in intracellular cation content. Since the Na electrochemical gradient is directed into the cell, net Na uptake was the result of Na flux via dissipative pathways. The addition of 10(-4)M ouabain to suspensions of flounder erythrocytes was without effect upon net water movements during volume regulation. The presence of ouabain did however lead to a decreased ration of intracellular K:Na. Analysis of net Na and K fluxes in the presence and absence of ouabain led to the conclusion that Na and K fluxes via both conservative and dissipative pathways are increased in response to osmotic swelling or shrinkage. In addition, the Na and K flux rate through both pump and leak pathways decreased in a parallel fashion as cell volume was regulated. Taken as a whole, the Na and K movements through the flounder erythrocyte membrane demonstrated a functional dependence during volume regulation.     

Hemoglobin-haptoglobin receptor in rat liver plasma membrane

The presence of a receptor specific for the hemoglobin . haptoglobin complex is demonstrated in rat liver plasma membranes. Hemoglobin . haptoglobin complex, administered intravenously to rats, was cleared from the circulation at a constant rate with exclusive incorporation of the molecule into hepatocytes. This incorporation was unaffected by the simultaneous injection of asialoglycoprotein or heme . hemopexin complex. In vitro experiments with isolated liver plasma membranes indicated the absence of competitive binding of these molecules to the membrane and suggested that this receptor might recognize an altered conformation of the haptoglobin moiety of the complex resulting from the binding with hemoglobin. These observations suggest that the mechanism of recognition and binding of hemoglobin . haptoglobin complex by the receptor is different from that of the asialoglycoprotein receptor or heme . hemopexin receptor.     

Characterization of a somatomedin (insulin-like growth factor) synthesized by fetal rat liver organ cultures.

Explants of 19- to 20-day fetal rat liver synthesize polypeptides biochemically and immunologically related to the well characterized somatomedin (insulin-like growth factor) BRL-MSA, multiplication-stimulating activity. Fetal MSA was purified from media conditioned by fetal liver explants by chromatography on Sephadex G-75 under acid conditions. Partially purified fetal MSA: 1) inhibited the binding of BRL-MSA to the MSA receptor of rat liver plasma membranes, to somatomedin-binding proteins from rat serum, and to rabbit anti-BRL-MSA serum; 2) had a molecular weight of 4,500 to 12,500 determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate; 3) stimulated the incorporation of [3H]thymidine into the DNA of chick embryo fibroblasts and induced cell multiplication; 4) stimulated glucose oxidation in rat adipocytes and weakly inhibited the binding of insulin to the insulin receptors of IM-9 lymphocytes; and 5) stimulated sulfate uptake in costal cartilage from hypophysectomized rats. These activities were associated with the same molecular species in fetal MSA preparations following disc acrylamide electrophoresis and co-migrated with active BRL-MSA peptides.     

Some properties of the citrate synthase from the extreme halophile, Halobacterium cutirubrum.

1. Citrate synthase [citrate oxaloacetate-lyase (CoA-acetylating), EC 4.1.3.7] was purified about 400-fold from the extreme halophile, Halobacterium cutirubrum, by a method involving (NH4)2SO4 fractionation, chromatography on DEAE-cellulose and hydroxyapatite and gel filtration on Sephadex G-200. 2. The purified enzyme was best activated by high concentrations of KCl (3M); the chlorides of other cations and K+ salts of other anions (Br-, NO3-, SCN-) were less effective than KCl as activators. The enzyme was best stabilized by high concentrations of NaCl or KCl. Cold-lability was found in the presence of 3M-KCl, but not in the presence of NaCl at concentrations up to 5M. The results suggest that both the shielding of negative charges on the enzyme molecule and the stabilization of hydrophobic bonds by high KCl concentrations were required for maximum activity of the enzyme. 3. The double-reciprocal plots for acetyl-CoA or oxaloacetate at several concentrations of the co-substrate intersected at the abscissa in the presence of either KCl or NaCl, at either 1 or 3M. The Km for oxaloacetate increased about fivefold with the salt concentration, from 1 to 3M.     

Biodeterioration of Mayan buildings at uxmal and tulum,Mexico

Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation.