[Kugelberg-Welander disease in 9 members of a family through 4 generations].
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Adolescent↗
Biomedical subjects
S H Lin
Publications and source records attributed to S H Lin.
Multicentric basal cell tumors in a cat.
Four basal cell tumors were diagnosed in an adult spayed female domestic longhair cat. Surgical excision was curative. Basal cell tumors in cats usually are solitary, slow growing, benign epithelial neoplasms. The multicentric nature of these neoplasms in this patient was uncharacteristic of typical basal cell tumors in cats.
Animals↗
Dose-dependent nonlinear response of the main phase-transition temperature of phospholipid membranes to alcohols.
The effect of 1-alkanols upon the main phase-transition temperature of phospholipid vesicle membranes between gel and liquid-crystalline phases was not a simple monotonic function of alkanol concentration. For instance, 1-decanol decreased the transition temperature at low concentrations, but increased it at high concentrations, displaying a minimal temperature. This concentration-induced biphasic effect cannot be explained by the van't Hoff model on the effect of impurities upon the freezing point. To explain this nonlinear response, a theory is presented which treats the effect of 1-alkanols (or any additives) on the transition temperature of phospholipid membranes in a three-component mixture. By fitting the experimental data to the theory, the enthalpy of the phase transition delta H* and the interaction energy, epsilon*AB between the additive and phospholipid molecules may be estimated. The theory predicts that when epsilon*AB greater than 2 (where epsilon*AB = epsilon AB/RT0, T0 being the transition temperature of phospholipid), both minimum and maximum transition temperatures should exist. When epsilon*AB = 2, only one inflection point exists. When epsilon*AB less than 2, neither maximum nor minimum exists. The alkanol concentration at which the transition temperature is minimum (Xmin) depends on the epsilon*AB value: the larger the epsilon*AB values, the smaller the Xmin. When epsilon*AB is large enough, Xmin values become so small that the plot delta T vs. X shows positive delta T in almost all alkanol concentrations. The interaction energy between 1-alkanols and phospholipid molecules increased with the increase in the carbon chain-length of 1-alkanols. In the case of the dipalmitoylphosphatidylcholine vesicle membrane, the carbon chain-length of 1-alkanols that caused predominantly positive delta T was about 12.
Alcohols↗
Moving right atrial mass associated with hepatoma. Two cases detected by echocardiography.
Hepatoma with right atrial (RA) metastasis is rare, and to our knowledge, the echocardiographic description of a RA mass associated with hepatoma has never been described. Herein we report two cases of hepatoma, whose two-dimensional echocardiograms demonstrated a RA mass protruding into right ventricle during diastole, mimicking RA myxoma. However, in contrast to RA myxoma, these RA masses could be traced to the inferior venae cavae, which were dilated and filled with tumor echoes. Since prompt diagnosis and removal of these RA masses might prevent sudden cardiac death, we advocate performing echocardiographic examination in patients with hepatoma, who have cardiac symptoms or signs.
Carcinoma, Hepatocellular↗
Anesthetics release unfreezable and bound water in partially hydrated phospholipid lamellar systems and elevate phase transition temperature.
A dimyristoylphosphatidylcholine multilamellar system with varied water content was prepared by dessiccating sonicated vesicles in vacuo. The water content in the sample was determined by gas chromatography after dissolving the multilamellar system in water-free benzene. Differential scanning microcalorimetry revealed several endothermic peaks in the heating scan at subzero temperature, ranging from -25 to -3 degrees. The peaks that appeared in the subzero temperature range indicate the existence of water molecules bound to the lipid head groups, differing from free water that freezes at 0 degrees. The difference between the amount of water molecules that froze in calorimetry and the total amount of water detected by gas chromatography indicates the presence of unfreezable, tightly bound water molecules. The relative amount of free, intermediate, and unfreezable water was estimated by comparing the differential scanning microcalorimetry data with gas chromatography measurements. The addition of halothane and 1-hexanol significantly decreased the intermediately bound water peaks. The anesthetics dehydrated the lamellar system. The phase polymorphism of partially hydrated phospholipid multilayers is well known, and the temperature that corresponds to the main phase transition of fully hydrated lipid membranes shifts to a higher temperature. The addition of anesthetics increased the phase transition temperature when the water content was less than 18 wt%. This result is the complete reverse of the depressant action of anesthetics in fully hydrated lipid membranes. The present anesthetic effect upon the elevation of the transition temperature is apparently caused by anesthetic-induced dehydration of the lipid-water interface at the present experimental condition.
Anesthetics↗
The rat liver plasma membrane high affinity (Ca2+-Mg2+)-ATPase is not a calcium pump. Comparison with ATP-dependent calcium transporter.
The high affinity (Ca2+-Mg2+)-ATPase purified from rat liver plasma membrane (Lin, S.-H., and Fain, J. N. (1984) J. Biol. Chem. 259, 3016-3020) has been further characterized. This enzyme also possesses Mg2+-stimulated ATPase activity with K0.5 of 0.16 microM free Mg2+. However, the Vm of the Mg2+-stimulated activity is only half that of the Ca2+-stimulated ATPase activity. The effects of Ca2+ and Mg2+ on this enzyme are not additive. Both the Ca2+-stimulated ATPase and Mg2+-stimulated ATPase activities have similar affinities for ATP (0.21 mM and 0.13 mM, respectively) and similar substrate specificities (they are able to utilize ATP, GTP, UTP, CTP, ADP, and GDP as substrates); both activities are not inhibited by vanadate, p-chloromercuribenzoate, ouabain, dicyclohexylcarbodiimide, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, oligomycin, F-, N-ethylmaleimide, La3+, and oxidized glutathione. These properties of the Mg2+- and Ca2+-ATPases indicate that both activities reside on the same protein. A comparison of the properties of this high affinity (Ca2+-Mg2+)-ATPase with those of the liver plasma membrane ATP-dependent Ca2+ transport activity reconstituted into artificial liposomes (Lin, S.-H. (1985) J. Biol. Chem. 260, 7850-7856) suggests that this high affinity (Ca2+-Mg2+)-ATPase is not the biochemical expression of the liver plasma membrane Ca2+ pump. The function of this high affinity (Ca2+-Mg2+)-ATPase remains unknown.
Adenosine Triphosphate↗
Novel ATP-dependent calcium transport component from rat liver plasma membranes. The transporter and the previously reported (Ca2+-Mg2+)-ATPase are different proteins.
An ATP-dependent calcium transport component from rat liver plasma membranes was solubilized by cholate and reconstituted into egg lecithin vesicles by a cholate dialysis procedure. The uptake of Ca2+ into the reconstituted vesicles was ATP-dependent and the trapped Ca2+ could be released by A23187. Nucleotides, including ADP, UTP, GTP, CTP, GDP, AMP, and adenyl-5'-yl beta, gamma-imidophosphate, and p-nitrophenylphosphate did not substitute for ATP. The concentration of ATP required for half-maximal stimulation of Ca2+ uptake into the reconstituted vesicles was 6.2 microM. Magnesium was required for calcium uptake. Inhibitors of mitochondrial calcium-sequestering activities, i.e. oligomycin, sodium azide, ruthenium red, carbonyl cyanide p-trifluoromethoxyphenylhydrazone, and valinomycin did not affect the uptake of Ca2+ into the vesicles. In addition, strophanthidin and p-chloromercuribenzoate did not affect the transport. Calcium transport, however, was inhibited by vanadate in a concentration-dependent fashion with a K0.5 of 10 microM. A calcium-stimulated, vanadate-inhibitable phosphoprotein was demonstrated in the reconstituted vesicles with an apparent molecular weight of 118,000 +/- 1,300. These properties of Ca2+ transport by vesicles reconstituted from liver plasma membranes suggest that this ATP-dependent Ca2+ transport component is different from the high affinity (Ca2+-Mg2+)-ATPase found in the same membrane preparation (Lotersztajn, S., Hanoune, J. and Pecker, F. (1981) J. Biol. Chem. 256, 11209-11215; Lin, S.-H., and Fain, J.N. (1984) J. Biol. Chem. 259, 3016-3020). When the entire reconstituted vesicle population was treated with ATP and 45Ca in a buffer containing oxalate, the vesicles with Ca2+ transport activity could be separated from other vesicles by centrifugation in a density gradient and the ATP-dependent Ca2+ transport component was purified approximately 9-fold. This indicates that transport-specific fractionation may be used to isolate the ATP-dependent Ca2+ transport component from liver plasma membrane.
Adenosine Triphosphate↗
Influence of an extrinsic cross-link on the folding pathway of ribonuclease A. Kinetics of folding-unfolding.
The kinetics of folding/unfolding of cross-linked Lys7-dinitrophenylene-Lys41-ribonuclease A were studied and compared to those of unmodified ribonuclease A (RNase A) at various concentrations of guanidine hydrochloride. The folding of the denatured cross-linked protein involved one fast-folding species (22 +/- 4%) and two slow-folding species, as observed in unmodified ribonuclease A. Also, a nativelike intermediate, analogous to that reported previously for unmodified ribonuclease A [Cook, K. H., Schmid, F. X., & Baldwin, R. L. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 6157], has been detected on the folding pathway of cross-linked ribonuclease A. The extrinsic cross-link between Lys7 and Lys41 did not affect the rate constants for the folding kinetics of these three species. The cross-link did, however, significantly affect the rate constant for unfolding of the native protein. The conformation of the protein in the transition state of the unfolding pathway was deduced from an analysis of the kinetic data. It appears that the 41 N-terminal residues are unfolded in the transition state of the unfolding pathway. Thus, the unfolding pathway of RNase A is sequential in that further unfolding (after the transition state) follows the unfolding of the 41 N-terminal residues. Also, the conformation of the 41 N-terminal residues does not play a role in the folding pathway. Presumably, if the cross-link were introduced instead between two other residues that are in the segment(s) involved in the rate-limiting step(s), it could increase the refolding rate constants and possibly the concentration of fast-folding species.
Cross-Linking Reagents↗
Preliminary crystallographic data for cross-linked (lysine7-lysine41)-ribonuclease A.
A cross-linked derivative of ribonuclease A, N epsilon,N epsilon'-(2,4-dinitrophenylene-1,5)-lysine7-lysine41)- RNase A, has been crystallized by dialysis against 30% (v/v) ethanol/water mixtures buffered at high pH. Single crystals belong to the orthorhombic space group P212121, a = 37.2 A, b = 41.2 A, b = 41.2 A, with one molecule in the crystallographic asymmetric unit.
Cross-Linking Reagents↗
[Cesarean section in eclampsia].
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Cesarean Section↗
Influence of an extrinsic cross-link on the folding pathway of ribonuclease A. Conformational and thermodynamic analysis of cross-linked (lysine7-lysine41)-ribonuclease a.
A cross-linked ribonuclease A derivative, Lys7-dinitrophenylene-Lys41-ribonuclease A, has been prepared and characterized for ultimate use in protein-folding experiments. Immunochemical assays and spectroscopic measurements demonstrated that the introduction of this artificial cross-link does not perturb the native conformation of ribonuclease A. The cross-linked protein exhibited a reversible thermal transition with Tm = 53 degrees C at pH 2.0, which is 25 degrees C higher than that of unmodified ribonuclease A under the same conditions. The denatured form of the cross-linked ribonuclease A has a conformational chemical potential that is 4.9 kcal/mol higher than that of the denatured form of unmodified ribonuclease A at 40 degrees C and pH 2.0, assuming that the cross-linked and the unmodified proteins have the same conformational chemical potential in the native conformation. This is in good agreement with a theoretical value of 5.2 kcal/mol, calculated from the reduction of chain entropy of the denatured form upon introduction of the extrinsic cross-link. Thus, it is concluded that the extrinsic cross-link between Lys7 and Lys41, formed by the dinitrophenylene group, does not affect the native conformation of ribonuclease A but destabilizes the denatured conformation, probably by decreasing its chain entropy.
Chemical Phenomena↗
Purification of (Ca2+-Mg2+)-ATPase from rat liver plasma membranes.
The Ca2+-stimulated, Mg2+-dependent ATPase from rat liver plasma membranes was solubilized using the detergent polyoxyethylene 9 lauryl ether and purified by column chromatography using Polybuffer Exchanger 94, concanavalin A-Sepharose 4B, and Sephadex G-200. The molecular weight of the enzyme, estimated by gel filtration in the presence of the detergent on a Sephadex G-200 column, was 200,000 +/- 15,000. The enzyme was purified at least 300-fold from rat liver plasma membranes and had a specific activity of 19.7 mumol/mg/min. Polyacrylamide gel electrophoresis under nondenaturing conditions of the purified enzyme indicated that the enzymatic activity correlated with the major protein band. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, one major band in the molecular weight range of 70,000 +/- 5,000 was seen. The isoelectric point of the purified enzyme was 6.9 +/- 0.2 as determined by analytical isoelectric focusing. The enzyme was activated by Ca2+ with an apparent half-saturation constant of 87 +/- 2 nM for Ca2+. Calmodulin and trifluoperazine at the concentration of 1 microgram/ml and 100 microM, respectively, had no effect on the enzymatic activity.
Animals↗
Ca2+-Mg2+-ATPase in rat hepatocyte plasma membranes: inhibition by vasopressin and purification of the enzyme.
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Animals↗
Rapid changes in hepatocyte phosphoinositides induced by vasopressin.
Vasopressin stimulated a 40% decrease in [32P]phosphatidylinositol 4,5-bisphosphate and a 15% decrease in [32P]phosphatidylinositol within 30 s of addition to hepatocytes prelabeled for 60 min with 32P. In hepatocytes prelabeled with [3H]inositol for 60 min, vasopressin produced 20% breakdown of phosphatidylinositol and 33% breakdown of phosphatidylinositol 4,5-bisphosphate within 30 s. There was a 40% increase in total phosphatidylinositol 4,5-bisphosphate within 30 s of vasopressin addition. Breakdown of phosphatidylinositol accounted for disappearance of 95% of the inositol lipid label. In hepatocytes from rats labeled in vivo with [3H]inositol, vasopressin stimulated 10% loss of labeled phosphatidylinositol. Loss of [32P]phosphatidylinositol due to vasopressin was followed by reincorporation of label to levels greater than control while 32P reuptake into phosphatidylinositol 4,5-bisphosphate did not exceed control values. With in vitro [3H]inositol-labeled hepatocytes, loss of label from the phosphoinositides was followed by reuptake of tritium label to control levels. In hepatocytes labeled in vivo with [3H]inositol, reuptake of [3H]inositol label did not occur. These data indicate that the hormone-sensitive pool of hepatocyte phosphoinositides can be labeled by both in vitro and in vivo procedures. Vasopressin induces a rapid decrease of labeled phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate within 30 s.
Animals↗
Hormonal regulation of phosphatidylinositol breakdown.
Cyclic AMP and Ca2+ are intracellular mediators of hormone action. Catecholamines interact with beta adrenoceptors to activate adenylate cyclase or with alpha 2 adrenoceptors to inhibit adenylate cyclase. Alpha 1 adrenoceptor activation results in elevation of cytosol Ca2+ and an increased breakdown of phosphatidylinositol. In blowfly salivary glands, 5-hydroxytryptamine (5-HT) interacts with beta type receptors resulting in adenylate cyclase activation while alpha type receptors are involved in phosphatidylinositol breakdown and elevation of cytosol Ca2+. The link between Ca2+ mobilization and phosphatidylinositol breakdown remains to be established but breakdown of the receptor-regulated pool of phosphatidylinositol is not secondary to the rise in Ca2+. Direct addition of 5-HT to cell-free homogenates of blowfly salivary glands results in activation of phosphatidylinositol breakdown in the absence of Ca2+. In rat liver plasma membrane preparations, vasopressin increases phosphatidylinositol breakdown in the absence of Ca2+ or cytosol if deoxycholate is present. The data do not indicate whether hormone activation increases the availability of substrate to enzymatic hydrolysis or activates phospholipase C. However, they demonstrate that hormones directly accelerate phosphatidylinositol breakdown.
Animals↗
Stopped-flow cryoenzymology: detection of catalytic intermediates not observable at ambient temperatures.
Stopped-flow cryoenzymology has been used to study the reaction of porcine kidney cytosol leucine aminopeptidase [alpha-aminoacyl-peptide hydrolase(cytosol), EC 3.4.11.1] with L-leucylglycyldansyl hydrazide in 50% (vol/vol) methanol buffer over the -40 to 23 degrees C temperature range. Resonance energy transfer between tryptophan residues of the enzyme E and the dansyl group of the substrate S has been used to detect the formation and interconversion of reaction intermediates (E X S)i. Above 0 degrees C, a single intermediate E X S is formed and decays by first-order kinetics to products. However, at temperatures below -20 degrees C, a new intermediate (E X S)' is observed immediately after mixing, which relaxes to E X S within 100 msec. Because the detection of this new intermediate would not have been possible at ambient temperatures, this illustrates the value of stopped-flow cryoenzymology for studies of catalytic pathways.
Animals↗
Regulation of Ca2+-Mg2+-ATPase activity in hepatocyte plasma membranes by vasopressin and phenylephrine.
A high affinity Ca2+-stimulated, Mg2+-dependent ATPase (Ca2+-Mg2+-ATPase) was identified in microsomes and plasma membrane vesicles isolated from rat hepatocytes. The distribution of this enzyme was similar to that of the plasma membrane marker enzymes alkaline phosphodiesterase and 5'-nucleotidase. The Ca2+-Mg2+-ATPase had an apparent half-saturation constant of approximately 75 nM for Ca2+. After incubation of rat hepatocytes with 25 nM vasopressin for 3 min, the activity of Ca2+-Mg2+-ATPase was decreased 15-30%. The effect of vasopressin on the activity of this enzyme was near maximal after incubating hepatocytes with vasopressin for only 15 sec. The concentration of vasopressin needed for half-maximal inhibition of this enzyme in hepatocytes was approximately 6 nM. Treatment of the hepatocytes with 10 microM phenylephrine caused about a 10% decrease in ATPase activity while 10 nM glucagon or 200 microU/ml insulin did not affect the enzyme. These findings suggest that inhibition of the Ca2+-Mg2+-ATPase activity may be part of the mechanism by which vasopressin and alpha-adrenergic agonists elevate cytosolic Ca2+ in hepatocytes.
Animals↗
[Pathological changes and clinical features of hypothalamic lesions in cases of subarachnoid hemorrhage].
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Adult↗