Limax flavus agglutinin: properties of a sialic acid specific lectin and its biomedical application.
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Amino Acids↗
Biomedical subjects
R L Miller
Publications and source records attributed to R L Miller.
Inhibition of lymphocyte function by 9-deazaadenosine.
9-Deazaadenosine (c9Ado), a novel C-nucleoside, has been found to inhibit lymphocyte-mediated cytolysis (LMC) in a time-dependent manner. c9Ado inhibited LMC by 50% at concentrations of 10 and 0.07 microM after drug-pretreatment periods of 3 and 22 hr, respectively, although a 1-hr pretreatment of cytolytic lymphocytes with 100 microM c9Ado had no effect upon this lymphocyte function. c9Ado was metabolized rapidly and extensively to 9-deazaadenosine 5'-triphosphate (c9ATP) both by mouse cytolytic lymphocytes and by human erythrocytes. Adenosine kinase purified from rabbit liver phosphorylated c9Ado with a Km of 200 microM and a Vmax of 8% that for adenosine. The metabolic buildup of c9ATP in lymphocytes was accompanied by a large, time-dependent decrease in cellular ATP and by smaller percentage decreases in CTP, UTP and GTP. Among other biochemical effects examined, c9Ado was found to cause a decrease in lymphocyte cAMP content and appeared to be neither an inhibitor nor a substrate for S-adenosylhomocysteine hydrolase. Consistent with this latter result, L-homocysteine thiolactone had no effect on the inhibition of LMC by c9Ado. Neither the inhibition of LMC by c9Ado nor the metabolic formation of c9ATP in lymphocytes was affected by erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), indicating that c9Ado is not a substrate for adenosine deaminase. 5-Iodotubercidin, a non-competitive inhibitor (Kis = 9 nM, Ku = 20 nM) of adenosine kinase, prevented the above effects of c9Ado on lymphocyte function, c9ATP formation, and ATP levels. Either complete preservation (with coformycin) or partial replenishment (with adenosine plus EHNA) of ATP levels in c9Ado-treated lymphocytes resulted in partial restoration of cytolytic function to cells containing large amounts of c9ATP. These results suggest that c9Ado is inhibitory to LMC both because it causes a decrease in the absolute concentration of ATP within the cytolytic lymphocytes and because it permits the establishment within these cells of an unfavorable c9ATP:ATP ratio which impedes the utilization of ATP in a reaction essential to the execution of this lymphocyte function.
Adenosine Triphosphate↗
Purification of peanut (Arachis hypogaea) agglutinin isolectins by chromatofocusing.
This report describes the purification and isolation of the isolectins of peanut agglutinin (PNA). We find the affinity-purified PNA to have an amino acid composition similar to that reported by Lotan et al. (J. Biol. Chem. 250, 8518-8523 (1975)); however, our preparation contains three tryptophan residues per subunit rather than two as reported by Lotan et al. This higher tryptophan content is consistent with the extinction coefficient (E1 mg/ml 280) of 0.96 as previously reported (Fish et al., Arch. Biochem. Biophys. 190, 693-698 (1978)). The PNA, purified by affinity chromatography on lactosyl-Sepharose, contains six major and three minor components capable of agglutinating neuraminidase-treated erythrocytes. Seven of the isolectins were obtained in a highly purified form by chromatofocusing, a column chromatographic technique which separates proteins on the basis of their isoelectric points. Isoelectric focusing of the purified isolectins indicates that they have the following isoelectric points: A, 6.70; B, 6.55; C, 6.35; D, 6.25; E, 6.10; F, 5.90; and G, 5.70. Preliminary studies on the subunit composition of the isolectins are also presented.
Amino Acids↗
Hereditary hemorrhagic telangiectasia: prosthetic management and considerations.
The dentist should be aware of the signs, symptoms, and significance of hereditary hemorrhagic telangiectasia. A patient who had unusual involvement of the masticatory mucosa and for whom construction and function of complete dentures did not result in discomfort or oral bleeding is described. Dentures may have a positive effect on the size and number of telangiectasias. A gradual decrease in the size of a nodular lesion of the mandibular edentulous ridge is documented over a 3-year period.
Dental Care for Persons with Disabilities↗
Acute portal hypertension and reduced renal blood flow: an intestinal-renal neurogenic reflex.
In a series of experiments in anesthetized dogs, the origin and mechanism of reduced renal blood flow (RBF) during acute portal hypertension was investigated. With acute superior mesenteric vein (SMV) occlusion and normalization of cardiac hemodynamics RBF remained reduced at 66 +/- 14 ml/min compared to baseline of 160 +/- 25 ml/min (P less than 0.01). Neither acute superior mesenteric artery occlusion, nor acute hepatic portal hypoperfusion with normal SMV pressures maintained by SMV-caval shunt, resulted in reduction of RBF. Cross-perfusion studies failed to produce alterations of RBF in recipient dogs from donor dogs with SMV occlusion, reduced RBF, and normal cardiac outputs. Finally, splanchnic ganglionectomy prevented RBF reduction during SMV occlusion after volume restoration. We conclude that reduced RBF during acute portal hypertension is a result of an intestinal-renal neurogenic reflex initiated by intestinal venous congestion.
Animals↗
The differentiation of malignant lymphoma from anaplastic seminoma in a patient presenting with testicular and jaw swelling.
The histologic differentiation of anaplastic seminoma from lymphoma is often difficult. In the case presented, a malignant lymphoma showing prominent testicular and jaw involvement was initially interpreted as seminoma. The histologic and ultrastructural criteria for differentiation, as well as a comparison of the clinical and epidemiologic characteristics of these tumors, are discussed. A reassessment of previously reported cases of seminoma metastatic to the jaws/antrum, made relative to these data, suggests that in most cases the tumors may actually be lymphomas.
Diagnosis, Differential↗
Purine and pyrimidine metabolizing activities in Trichomonas vaginalis extracts.
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Animals↗
Demonstration and initial characterization of a latent collagenase secreted by human gingival fibroblasts.
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Cells, Cultured↗
Secretin: specific binding to rat brain membranes.
The binding of [125I]secretin to rat brain membranes was investigated. Radiolabeled secretin bound with high affinity (KD = 0.2 nM) to a single class of noninteracting sites. Binding was specific, saturable, and reversible. Regional distribution studies indicated that the specific binding was greatest in the cerebellum, intermediate in the cortex, thalamus, striatum, hippocampus, and hypothalamus, and lowest in the midbrain and medulla/pons. Pharmacological studies indicated that only secretin, but not other peptides, inhibits binding of [125I]secretin with high affinity. Also, certain guanine nucleotides inhibited high affinity binding. These data indicate that rat brain membranes possess high affinity binding sites specific for secretin and that with the use of [125I] secretin the kinetics, stoichiometry, specificity, and distribution of secretin receptors can be directly investigated.
Animals↗
Studies of the kallikrein-kinin system in patients with sickle cell anemia.
Eight patients with sickle cell anemia (SS hemoglobin) were found to have decreased plasma levels of prekallikrein compared to normal control subjects or patients with other types of anemia. The prekallikrein levels in the patients with sickle cell anemia were found to decrease further during a sickle cell crisis. These results suggest that components of the kallikrein-kinin system are profoundly affected in patients with sickle cell anemia, and during crises may play a role in the clinical presentation of patients.
Adolescent↗
Indirect calorimetry in postoperative patients with acute renal failure.
Oxygen consumption was measured and caloric expenditure calculated (indirect calorimetry) in ten adult patients with acute renal failure (ARF) following surgery. Eight patients recovered from ARF and six were discharged from the hospital. Caloric expenditure averaged 47 Kcal/kg/24 hours during the period of AFR. Attempts were made to match caloric replacement with expenditure based on indirect calorimetry, but was achieved in only one patient. Indirect calorimetry appears to be a practical method for guiding caloric replacement in these patients. Postoperative patients in ARF must undergo healing of incisions and bowel anastomoses, and contain infection. Since these patients are severely catabolic, it seems reasonable to treat them with adequate protein and calories and to use dialysis to control azotemia and water metabolism.
Acute Kidney Injury↗
Reduced plasma kininogen concentration during sickle cell crisis.
Eight patients with sickle cell anemia (SS hemoglobin) were found to have decreased plasma levels of kininogen compared to normal control subjects. The kininogen level of the patients with sickle cell anemia was decreased further during sickle cell crises. The results suggest that components of the kinin system are profoundly affected in patients with sickle cell anemia, and during crises may play a role in the clinical presentation of patients.
Adolescent↗
Inhibition of canine lung angiotensin converting enzyme by substance P.
We have studied inhibition of purified canine angiotensin converting enzyme by substance P and its nonapeptide derivative using Hip-His-Leu as the substrate. Kinetic studies indicated that both substance P and its nonapeptide derivative inhibited the hydrolysis of Hip-His-Leu at different concentrations. The mode of inhibition was competitive with a Ki of 1.15 microM for substance P. These results indicate that substance P is a potent inhibitor of angiotensin converting enzyme in vitro.
Angiotensin-Converting Enzyme Inhibitors↗
Phosphorylation of acyclovir diphosphate by cellular enzymes.
Acyclovir diphosphate (acyclo-GDP) is a metabolite of the antiviral drug acyclovir [9-(2-hydroxyethoxymethyl)guanine]. Seven enzymes capable of catalyzing the phosphorylation of GDP and dGDP (nucleoside diphosphate kinase, pyruvate kinase, creatine kinase, phosphoglycerate kinase, succinyl-CoA synthetase, phosphoenolpyruvate carboxykinase and adenylosuccinate synthetase) also catalyzed the phosphorylation of acyclo-GDP. In general, acyclo-GDP had a lower V'max and a higher K'm than either GDP or dGDP. None of these enzymes showed significantly higher rates of phosphorylation with GDP or acyclo-GDP in herpes simplex virus-infected Vero cells as compared to uninfected Vero cells. The contribution of each enzyme to the phosphorylation of acyclo-GDP in vivo was estimated from the kinetic data from the partially purified enzymes, the level of each enzyme in Vero cells, and the physiological concentrations of both substrates and inhibitors. The relative order of estimated rates of acyclo-GDP phosphorylation in Vero cells was phosphoglycerate kinase much greater than pyruvate kinase greater than phosphoenolpyruvate carboxykinase greater than nucleoside diphosphate kinase greater than succinyl-CoA synthetase greater than creatine kinase greater than adenylosuccinate synthetase. The calculated potential for acyclo-GDP phosphorylation by these enzymes was adequate to account for the amounts of acyclo-GTP formed in cell culture.
Acyclovir↗
Canine protothecosis: review of the literature and report of an additional case.
A review of protothecosis in dogs revealed that this malady usually begins in the gastrointestinal tract and progresses to systemic involvement. Clinical signs generally include bloody diarrhea or blood-stained feces as well as blindness, ataxia, and polyuria. Histologically, myriads of protothecal organisms in different stages of development are found in the granulomatous lesions. Two main species have been culturally identified: Prototheca zopfii and P wickerhamii. In the absence of cultural studies, species identification can be accomplished readily by immunofluorescence. The present case involved P zopfii infection in a 5-year-old female Cocker Spaniel that had bloody diarrhea, with a history of bloody diarrhea 6 months earlier.
Animals↗
Purification and macromolecular properties of a sialic acid-specific lectin from the slug Limax flavus.
A lectin (LFA) which is highly specific for sialic acid has been purified from the slug Limax flavus by a combination of ammonium sulfate fractionation and affinity chromatography on bovine submaxillary mucin coupled to Sepharose 4B. The affinity-purified lectin appeared homogeneous by electrophoresis in the presence of sodium dodecyl sulfate. Below 1 mg/ml at pH 7, LFA exists as a species of Mr = 44,000 which is composed of two equal sized subunits. Above 1 mg/ml, the protein solution was observed to behave as a rapidly associating-dissociating system. N-acetylneuraminic acid and N-glycolylneuraminic acid gave a 50% inhibition of agglutination of erythrocytes by LFA at 0.13 and 0.81 mM, respectively. Galactose, N-acetylgalactosamine, galactosamine, glucose, N-acetylglucosamine, glucosamine, mannose, arabinose, xylose, fucose, glucuronic acid, alpha-methyl-D-glucoside, alpha-methyl-D-mannoside, lactose, and sucrose were ineffective inhibitors at concentrations up to 10-25 mM. Bovine submaxillary mucin, a sialoprotein, was a potent inhibitor of hemagglutination by LFA. Upon treatment of the mucin with neuraminidase, loss of inhibitory activity was observed which was proportional to the loss of sialic acid from the mucin.
Amino Acids↗
Inhibition of canine lung angiotensin converting enzyme by ACTH and structurally related peptides.
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Adrenocorticotropic Hormone↗
N-acetylation regulates the behavioral activity of alpha-melanotropin in a multineurotransmitter neuron.
A multineurotransmitter neuronal system that synthesizes and secretes both acetylated and deacetylated forms of alpha-melantropin and beta-endorphin is present in rat and human brain. The N-acetylated from of alpha-melanotropin had more potent behavioral effects than the deacetylated alpha-melanotropin. In the case of beta-endorphin, however, the deacetylated form has been shown to be more potent than the acetylated form. Enzymatic N-acetylation appears to be an important regulatory process for modulating the behavioral activity of peptides secreted from the opiomelanotropinergic multineurotransmitter neuron.
Acetylation↗