Risks and rewards of kidney transplant.
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Humans↗
Biomedical subjects
A Sanchez
Publications and source records attributed to A Sanchez.
Magnetic properties of high-Tc superconducting grains.
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Journal Article↗
Effects of the antithrombitic agent PCA 4230 on agonist-induced Ca2+ entry and Ca2+ release in human platelets.
We have studied the effects of the antithrombitic agent PCA 4230 on the entry of Mn2+, used here as a Ca2+ surrogate for Ca2+ channels, and on the release of Ca2+ from the intracellular stores in stimulated human platelets loaded with fura-2. PCA 4230 prevented receptor-operated calcium entry activated by thrombin, ADP and collagen with no modification of the Ca2+ release from the intracellular stores. PCA 4230 also inhibited cytochrome P-450-mediated O-dealkylase activity with the same concentration-dependence as the thrombin-induced Mn2+ entry. These results suggest that the inhibitory effects of PCA 4230 on Ca2+ influx may be due to its interaction with cytochrome P-450, which has been proposed recently to be involved in the activation of receptor-operated Ca2+ channels. In addition, PCA 4230 inhibited both PAF-induced Ca2+ entry and Ca2+ release, behaving as a PAF-antagonist. All these effects contribute to explain the antithrombitic action of PCA 4230.
Blood Platelets↗
E.s.r. study of the alkaline degradation of disaccharides in methyl sulfoxide.
The degradation of a series of deoxy sugars and disaccharides in methyl sulfoxide-tetrabutylammonium hydroxide has been studied by e.s.r. spectroscopy. The generation of radicals and the types of radical formed are dependent on the anomeric configuration of non-reducing moieties and on the positions of the linkages and deoxy groups. Mechanisms for the pathways of degradation are proposed.
Carbohydrate Sequence↗
Low-dose alpha-interferon treatment of chronic myeloid leukemia.
We treated 29 patients with chronic-phase and accelerated chronic myeloid leukemia (CML) with alpha-interferon in a dose of 2 mU/m2 given subcutaneously daily for 30 days and then three times per week. Most had received prior treatment. Three patients have had sustained hematologic and karyotypic remissions after a median of 22 months of treatment. Three further patients have had complete hematologic and partial karyotypic remissions. At a median follow-up of 48 months, the median survival has not been reached. This dose of alpha-interferon may induce sustained remissions even in pretreated patients and may prolong survival in CML.
Adult↗
Effective splenectomy in familial isolated thrombocytopenia.
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Female↗
The nucleotide sequence of the L gene of Marburg virus, a filovirus: homologies with paramyxoviruses and rhabdoviruses.
The nucleotide sequence of the L gene of Marburg virus, strain Musoke, has been determined. The L gene has a single long open reading frame encoding a polypeptide of 2330 amino acids (MW 267,175) that represents the viral RNA-dependent RNA polymerase. The putative transcription start signal (3'CUACCUAUAAUU 5') and the termination signal (3' UAAUUCUUUUU 5') of the gene could be identified. Computer-assisted comparison of the L protein with L proteins of other nonsegmented negative-stranded RNA viruses (Paramyxoviridae: Sendai virus, Newcastle disease virus, human parainfluenza 3 virus, measles virus, human respiratory syncytial virus; Rhabdoviridae: vesicular stomatitis virus, rabies virus) revealed significant homologies primarily in the N-terminal half of the proteins. We have identified three common conserved boxes (A, B, and C) among filo-, paramyxo-, and rhabdovirus L proteins, which are probably involved in the polymerase function. The L proteins can be divided into an N-terminal half, which seems to accommodate the common enzymatic sites, and a C-terminal half carrying virus specific peculiarities. The data presented here suggest a common evolutionary history for all nonsegmented negative-stranded RNA viruses and show that filoviruses are more closely related to paramyxo- than to rhabdoviruses.
Amino Acid Sequence↗
Marburg virus, a filovirus: messenger RNAs, gene order, and regulatory elements of the replication cycle.
The genome of Marburg virus (MBG), a filovirus, is 19.1 kb in length and thus the largest one found with negative-strand RNA viruses. The gene order - 3' untranslated region-NP-VP35-VP40-GP-VP30-VP24-L-5' untranslated region-resembles that of other non-segmented negative-strand (NNS) RNA viruses. Six species of polyadenylated subgenomic RNAs, isolated from MBG-infected cells, are complementary to the negative-strand RNA genome. They can be translated in vitro into the known structural proteins NP, GP (non-glycosylated form), VP40, VP35, VP30 and VP24. At the gene boundaries conserved transcriptional start (3'-NNCUNCNUNUAAUU-5') and stop signals (3'-UAAUUCUUUUU-5') are located containing the highly conserved pentamer 3'-UAAUU-5'. Comparison with other NNS RNA viruses shows conservation primarily in the termination signals, whereas the start signals are more variable. The intergenic regions vary in length and nucleotide composition. All genes have relatively long 3' and 5' end non-coding regions. The putative 3' and 5' leader RNA sequences of the MBG genome resemble those of other NNS RNA viruses in length, conservation at the 3' and 5' ends, and in being complementary at their extremities. The data support the concept of a common taxonomic order Mononegavirales comprising the Filoviridae, Paramyxoviridae, and Rhabdoviridae families.
Base Sequence↗
Sequence analysis of the Marburg virus nucleoprotein gene: comparison to Ebola virus and other non-segmented negative-strand RNA viruses.
The first 3000 nucleotides from the 3' end of the Marburg virus (MBG) genome were determined from cDNA clones produced from genomic RNA and mRNA. Identified in the sequence was a short putative leader sequence at the extreme 3' end, followed by the complete nucleoprotein (NP) gene. The 5' end of the NP mRNA was determined as was the polyadenylation site for the NP gene. The transcriptional start (3' UUCUUCUUAUAAUU..) and termination (3' ..UAAUUCUUUUU) signals of the MBG NP gene are very similar to those seen with Ebola virus (EBO). In comparison to other non-segmented negative-strand RNA viruses, filovirus transcriptional signals are most similar to members of the Paramyxovirus and Morbillivirus genera. In vitro translation of a run-off transcript containing the entire MBG NP coding region produced an authentic NP. Sequence comparisons of the 3' end of the MBG and EBO genomes revealed weak nucleotide sequence similarity, but the predicted sequence of the first 400 amino acids of these viruses showed a high degree. This homology is encoded in divergent nucleotide sequences through different codon usages and substitutions of similar amino acids. A small region in the middle of the MBG and EBO NP sequences was found to contain a significant amino acid homology with NPs of paramyxoviruses and to a lesser extent with rhabdoviruses. Specific sites of conserved sequence are contained in hydrophobic domains and may have a common function. Alignments of the entire NP amino acid sequences of these viruses also suggest that filoviruses are more closely related to paramyxoviruses than to rhabdoviruses.
Amino Acid Sequence↗
Elevated plasma glucagon in amyotrophic lateral sclerosis.
This study shown an abnormality in glucagon levels that may explain the glucose intolerance, abnormal insulin reactions, and abnormal plasma amino acid levels seen in amyotrophic lateral sclerosis (ALS). We randomly administered two test meals, differing only in protein source (soy versus casein) at least 1 week apart and measured fasting and postprandial bloods for glucagon, insulin, and glucose levels in 11 ALS patients. With the soy test meal, glucagon levels were elevated in all ALS patients compared with controls: at fasting (237 +/- 111 versus 108 +/- 46 pg/ml, p less than 0.01) and 1/2 hour (389 +/- 94 versus 133 +/- 68 pg/ml, p less than 0.001), and 2 hours postprandial (379 +/- 75 versus 108 +/- 53 pg/ml, p less than 0.001). Glucagon levels after the casein test meal were also significantly elevated. Insulin was elevated by both test meals. Casein produced significant glucose intolerance.
Adult↗
Agonist-induced Ca2+ influx into human platelets is secondary to the emptying of intracellular Ca2+ stores.
We have studied the relation between the filling state of the intracellular Ca2+ stores and the plasma-membrane permeability to Mn2+, used here as a Ca2+ surrogate for Ca2+ channels. Emptying of the intracellular Ca2+ stores either by incubation in Ca(2+)-free medium or by treatment with low concentrations of the Ca2+ ionophore ionomycin accelerated the influx of Mn2+. Refilling of the Ca2+ stores by incubation in Ca(2+)-containing medium restores low Mn2+ permeability. This Ca(2+)-store-regulated permeability was inhibited by Ni2+ and by cytochrome P-450 inhibitors. Stimulation of platelets with thrombin produced Ca2+ release from the intracellular stores, which was followed, after a temperature-dependent lag (2 s at 37 degrees C; 5 s at 18 degrees C), by an acceleration of Mn2+ influx. Cytochrome P-450 inhibitors prevented the thrombin-induced Mn2+ influx, with little effect on the Ca2+ mobilization from the intracellular stores. Ki values were similar to those estimated for inhibition of the store-regulated permeability in non-stimulated platelets. Similar results were found in platelets stimulated by platelet-activating factor or by ADP. We propose that agonist-induced Ca2+ (Mn2+) influx in platelets is secondary to the emptying of the intracellular Ca2+ stores. The activation of the plasma-membrane Ca2+ (Mn2+) pathway may take place by a mechanism involving microsomal cytochrome P-450, similar to that described previously in thymocytes [Alvarez, Montero & García-Sancho (1991) Biochem. J. 274, 193-197] and neutrophils [Montero, Alvarez & García-Sancho (1991) Biochem. J. 277, 73-79].
Adenosine Diphosphate↗
The role of intracellular acidification in calcium mobilization in human neutrophils.
Propionic acid induces a calcium mobilization in human neutrophils which is prevented by pretreatment with phorbol ester or pertussis toxin. The effect is reminiscent of that of chemotactic factors and leukotriene B4 and was attributed to cytoplasmic acidification (Naccache, P.H. et al. (1988) J. Cell. Physiol. 136, 118-124). We show there that other weak acids also induced cytoplasmic alkalinization and calcium mobilization. However, addition of trimethylamine together with propionic acid prevented the cytoplasmic acidification without modifying the calcium mobilization. Propionic acid increased the production of inositol phosphates but this effect was largely prevented by the joint addition of trimethylamine. The ionophores nigericin and monensin can both be forced to produce either cytoplasmic acidification or alkalinization by manipulating the extracellular concentrations of Na+, K+ or H+. Both ionophores produced calcium mobilization in all the cases, irrespective of the direction of the cytoplasmic pH shift. The ionophores were documented to collapse existing pH gradients among the cytoplasm and intracellular compartments. We conclude that the calcium-mobilizing effect of propionic acid and other weak acids is not due to the acidification of the cytoplasm. Our results are consistent, however, with calcium mobilization induced by weak acids and ionophores arising from acidification of an alkaline intracellular compartment.
Calcium↗
Monoclonal antibodies to three strains of hantaviruses: Hantaan, R22, and Puumala.
Thirty hybrid cell lines that produce monoclonal antibodies to three strains of hantaviruses have been generated and characterized. One clone specific to Hantaan 76-118 strain, four clones specific to Rattus strains and one clone specific to Puumala virus have been identified. Most of the monoclones produced antibodies specific to nucleoproteins. Only two monoclones were found to produce glycoprotein specific, neutralizing antibodies. The immunofluorescent (IFA) staining patterns of the monoclonal antibodies show consistent correlation with viral protein specificities as described for other hemorrhagic fever viruses. Cross-reactivity studies with hantaviruses tested demonstrate conserved antigenic sites on nucleoproteins among these hantaviruses tested. Puumala specific monoclones, produced for the first time, reveal both conserved and strain specific sites on the viral nucleoproteins of the Scandinavian virus.
Animals↗
Efficient in vitro translation and processing of the rubella virus structural proteins in the presence of microsomes.
In the structural protein open reading frame (SP-ORF) of rubella virus (RUB), the sequences for the three virion proteins occur in the order NH2-C-E2-E1-COOH with hydrophobic, consensus signal sequences preceding the amino termini for each of the two membrane proteins (T. K. Frey and L. D. Marr, 1988 Gene 62, 85-100). In vitro translation in the presence of microsomes of RNA transcripts from a plasmid containing the SP-ORF resulted in production and accurate processing of the three structural proteins. Since in the absence of microsomes the 110-kDa precursor of these proteins is produced, this finding indicated that the cleavage events in processing of the precursor were mediated by signalase. To study the C-E2 processing event, a DNA construct was made which contained the sequences for E2 beginning at the NH2 terminus of the hydrophobic consensus signal and extending through to the NH2 terminus of E1. In vitro translation of transcripts from this construct in the presence of microsomes resulted in accurate processing of E2 confirming that the hydrophobic sequence was a signal sequence and demonstrating it could function externally as well as internally within the 110-kDa precursor. To determine if the E2 signal was maintained on C after cleavage of the precursor by signalase, the SP-ORF plasmid was mutagenized to place translation termination codons at either the NH2 or COOH side of the E2 signal sequence such that C protein lacking or containing the E2 signal would be produced. As expected, the C-minus-signal protein migrated more rapidly in polyacrylamide gels than did the C-plus-signal protein. C translated from the SP-ORF construct as well as authentic C from infected cells comigrated with the C-plus-signal protein, indicating that the E2 signal was not removed. In a corollary study, it was found that RUB C protein was phosphorylated in vivo, although the percentage of the protein phosphorylated was not determined.
Animals↗
Vaccinia-vectored expression of the rubella virus structural proteins and characterization of the E1 and E2 glycosidic linkages.
The maturation of rubella virus (RV) glycoprotein E2 from the single intracellular species (E2i; MW = 40 kDa) to the heterodisperse virion species (E2v; MW = 42 to 47 kDa), was studied by pulse-chase radiolabeling in Vero cells infected with RV or with recombinant vaccinia viruses (VVs) which express the entire RV structural protein open reading frame (VV-CE2E1) or glycoprotein E2 independently (VV-E2). The RV proteins expressed by the recombinant VVs comigrated with authentic RV intracellular proteins. In pulse-chase experiments, performed in both RV- and VV-CE2E1-infected cells, the amount of pulse-labeled E2i was substantially reduced during a 3- to 4-hr chase; during the same chase the amount of pulse-labeled E1 and C did not change. The concomitant appearance of the E2v forms was not observed. In contrast, in VV-E2-infected cells, no reduction in the amount of E2i occurred after as long as a 10-hr chase. Western blots using anti-E2 monoclonal antibodies showed that E2i was the predominant E2 species in cells infected with RV, VV-CE2E1, and VV-E2. However, minor amounts of three discrete species which comigrated within the extent of the E2v smear were also detected in cells infected with all three viruses, indicating that some degree of intracellular processing to E2v did occur. The disappearance of E2i during pulse-chase radiolabeling without the concomitant appearance of detectable E2v and the predominance of this labile form under steady-state conditions as revealed by Western blot analysis suggested that E2i was selectively turned over in both RV- and VV-CE2E1-infected cells. Such turnover was not apparent in VV-E2-infected cells, indicating that association with C and E1 was necessary for turnover to occur. Endoglycosidase digestion experiments and glycan differentiation assays revealed that E2v contained O-linked glycans. The presence of O-glycans on E2v accounted for part of the difference in size between E2v and E2i. Both virion E1 and E2 were found to contain high-mannose, hybrid-type, and complex-type N-glycans. Heterogeneity existed in the extent of processing of these glycans among individual E1 and E2 molecules.
Animals↗
Plasma amino acids and the insulin/glucagon ratio as an explanation for the dietary protein modulation of atherosclerosis.
The amino acid composition of the diet influences the postprandial levels of plasma amino acids along with the hormones insulin and glucagon in humans fed single test meals identical in composition except for protein source. Soy protein (hypocholesterolemic), vs. casein (hypercholesterolemic), contains a higher amount of arginine and glycine and induces an increase in postprandial arginine and glycine. Soy protein induces a low postprandial insulin/glucagon ratio in both hypercholesterolemic and normocholesterolemic subjects. Casein induces a high postprandial insulin/glucagon ratio among hypercholesterolemic subjects. Amino acids such as arginine and glycine are associated with a decrease, while lysine and branched-chain amino acids are associated with increased serum cholesterol levels. Our data are consistent with the hypothesis that the control of cholesterol by insulin and glucagon is regulated by dietary and plasma amino acids. From this hypothesis the insulin/glucagon ratio is proposed as an early metabolic index of the effect of dietary proteins on serum cholesterol levels, a risk factor and a common mechanism through which dietary and lifestyle factors influence cardiovascular disease.
Amino Acids↗
Plasma amino acids and the insulin/glucagon ratio as an explanation for the dietary protein modulation of atherosclerosis.
The amino acid composition of the diet influences the postprandial levels of plasma amino acids along with the hormones insulin and glucagon in humans fed single test meals identical in composition except for protein source. Soy protein (hypocholesterolemic), versus casein (hypercholesterolemic), contains a higher amount of arginine and glycine and induces an increase in postprandial arginine and glycine. Soy protein induces a low postprandial insulin/glucagon ratio in both hypercholesterolemic and normocholesterolemic subjects. Casein induces a high postprandial insulin/glucagon ration among hypercholesterolemic subjects. Amino acids such as arginine and glycine are associated with a decrease, while lysine and branched-chain amino acids are associated with increased serum cholesterol levels. Our data are consistent with the hypothesis that the control of cholesterol by insulin and glucagon is regulated by dietary and plasma amino acids. From this hypothesis the insulin/glucagon ratio is proposed as an early metabolic index of the effect of dietary proteins on serum cholesterol levels, a risk factor and a common mechanism through which dietary and lifestyle factors influence cardiovascular disease.
Amino Acids↗
Human T cells recognize multiple epitopes of an immediate early/tegument protein (IE62) and glycoprotein I of varicella zoster virus.
Infection with varicella zoster virus (VZV) elicits persistent cell-mediated immunity directed against the immediate early (IE62) protein and the glycoprotein I (gp I) in most healthy subjects. In these experiments, synthetic peptides corresponding to residues of the IE62 protein and gp I were used to identify linear amino acid sequences of these immunogenic VZV proteins that were recognized by peripheral blood T lymphocytes from VZV-immune individuals of known major histocompatibility complex (MHC) type. All of 12 VZV-immune donors had T-cell proliferative responses, defined as a stimulation index (SI) greater than or equal to 2.0, to at least two of ten synthetic IE62 peptides; the mean number of IE62 peptides recognized by T cells from VZV-immune donors was seven. Five of the ten IE62 peptides stimulated T cells from 75% to 83% of the VZV-immune donors; the other five IE62 peptides were recognized by T cells from 42% to 67% of the subjects. All VZV-immune donors also had T proliferation responses to at least two of ten synthetic gp I peptides; the mean number of peptides recognized was six. Six of the ten gp I peptides were recognized by T cells from 67% to 92% of the VZV-immune donors; the frequency of donors responding to the other gp I peptides ranged from 42% to 58%. None of five nonimmune donors demonstrated T-cell proliferation to any of the IE62 or gp I peptides. A combination of two IE62 peptides provided epitopes that could be recognized by T cells from all twelve VZV-immune donors, regardless of DR type. Similarly, one gp I peptide in combination with either of two other gp I peptides induced proliferation of T cells from all immune subjects. Memory T cells with specificity for multiple short amino acid sequences of the IE62 protein and gp I were detected in subjects who had had primary VZV infection more than 20 years earlier. These observations indicate that natural VZV infection elicits a diverse cell-mediated immune response to viral proteins that is not restricted to only one or two immunodominant regions. Although the usefulness of peptide vaccines remains to be established, multiple epitopes of the IE62 protein and gp I were identified that could be presented by antigen-presenting cells (APC) and recognized by T cells from most subjects in an "outbred" human population.
Amino Acid Sequence↗