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E Flores

Publications and source records attributed to E Flores.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Non-Hodgkin's lymphomas associated with the acquired immunodeficiency syndrome. A multicenter clinical study of 77 cases].

BACKGROUND: The aim of the present was to study the prevalence of non Hodgkin's lymphoma (NHL) in AIDS patients as well as the clinicopathologic characteristics, response to treatment and survival. METHODS: From January 1984 to January 1991, 77 patients with NHL associated with AIDS diagnosed in 9 hospitals in Madrid were retrospectively studied. RESULTS: Ninety-two per cent of the patients were men (mean age 30 years: range: 9-66 years), 62% were intravenous drug abusers and 20 (26%) homosexuals. Pathologic study determined that 62 (80%) patients had high grade NHL (44% small noncleaved), 17% immunoblastic and 20% unclassifiable, and 15 (20%) had intermediate grade (16% diffuse large cell) being all the cases of the B immunophenotype. Sixty-five per cent were in advanced stages and 69% had B symptoms. Extranodal localizations were present in 88%, bone marrow in 29% and CNS in 29%. Six cases had primary CNS lymphomas. 50% of the patients had less than 200 x 10(6)/l CD4 lymphocytes. Forty-seven patients were evaluable for response to chemotherapy: 12 (26%) showed a complete response 27 (57%) a partial response and 8 (17%) did not respond. Opportunistic infections developed in 18%. The estimated survival at 3 years was 14% (median 6 months). On univariate analysis the parameters related to the worst survival were: primary CNS lymphoma, liver involvement, lack of treatment response, LDH > or = 300 UI/l, alkaline phosphatase > or = 500 UI/l and ESR > or = 70 mm. CONCLUSIONS: Non Hodgkin's lymphomas associated with AIDS usually behave in an "aggressive" way with a high frequency of advanced stages, B symptoms, high grade histologic subtypes and extranodal involvement. Response to treatment is poor, bone marrow toxicity frequent and survival short.

Adolescent↗
PubMed1995

Amino acid transport systems required for diazotrophic growth in the cyanobacterium Anabaena sp. strain PCC 7120.

Uptake of 16 amino acids by the filamentous, heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 was characterized with regard to kinetic parameters of transport, intracellular accumulation of the transported amino acids, and sensitivity of the transport process to energy metabolism inhibitors. Mutants resistant to certain toxic analogs of some amino acids were isolated that were impaired in amino acid transport. Results obtained in this study, together with those reported previously (A. Herrero and E. Flores, J. Biol. Chem. 265:3931-3935, 1990), suggest that there are at least five amino acid transport systems in strain PCC 7120: one high-affinity, active system for basic amino acids; one low-affinity, passive system for basic amino acids; two high-affinity, active systems with overlapping, but not identical, specificities for neutral amino acids; and one putative system for acidic amino acids. Some of the amino acid transport mutants were impaired in diazotrophic growth. These mutants were unable to develop a normal percentage of heterocysts and normal nitrogenase activity in response to nitrogen stepdown. Putative roles for the amino acid transport systems in uptake of extracellular amino acids, recapture of amino acids that have leaked from the cells, and intercellular transfer of amino acids in the filaments of Anabaena sp. strain PCC 7120 are discussed.

Amino Acids↗
PubMed1995

Effects of oral administration of zinc and diiodohydroxyquinolein on plasma zinc levels of uremic patients.

Patients with chronic renal failure often have low plasma zinc (Zn) levels. Some factors that may account for abnormal Zn metabolism in these patients are low dietary Zn intake, a specific Zn transport defect, or absence of intestinal Zn ligand. In this study Zn supplementation and a Zn-chelating drug, diiodohydroxyquinolein (DQ), were used to assess the effects of Zn intake and Zn transporters on Zn plasma levels in patients with chronic renal failure. To meet this objective, 20 uremic patients were randomly assigned to one of the following groups of treatment: group 1 received placebo; group 2 Zn sulfate (100 mg/day p.o.), group 3 DQ (80 mg/day p.o.), and group 4 received Zn sulfate plus DQ at the same dosages as in groups 2 and 3. The Zn plasma levels were measured in venous samples, before and after 1 and 2 weeks of treatment, by atomic absorption spectrophotometry. The Zn plasma levels increased in group 2 patients from 8 +/- 0.2 to 10 +/- 0.4 and 11 +/- 0.9 mumol/l by the end of the 1st and 2nd weeks of treatment, respectively. In group 4 patients, the Zn plasma levels increased even more: from 9 +/- 0.1 to 14 +/- 1.6 and 13 +/- 2.1 mumol/l respectively. The plasma Zn concentration of group 1 and 3 patients remained at basal levels. These results show that DQ, when given along with Zn sulfate supplements, causes a greater increase in plasma Zn levels than that caused by either drug given alone.

Administration, Oral↗
PubMed1995

Factors associated with Taenia solium cysticercosis: analysis of nine hundred forty-six Peruvian neurologic patients. Cysticercosis Working Group in Peru (CWG).

In most developing countries, 10% of acute neurologic cases are patients with neurocysticercosis (NCC). Determining specific factors associated with contracting NCC will facilitate its diagnosis and prevention. We examined multiple socioeconomic, demographic, environmental, medical, and behavioral characteristics of 946 Peruvian neurologic patients for a correlation with NCC, which was diagnosed by the highly specific and sensitive electroimmunotransfer blot (EITB) or immunoblot assay. Eighteen percent (172 of 932) of serum samples and 28% (101 of 362) of cerebrospinal fluid samples were EITB-positive. The proportion of EITB-positive persons was similar for all socioeconomic levels. Significant factors associated with NCC were: 1) being born outside Lima, 2) having raised pigs, 3) more than 20 years of age, 4) a history of seizures, and 5) a history of taeniasis. Of these factors, raising pigs is the only one that is amenable to intervention, via improvements in animal husbandry.

Adolescent↗
PubMed1994

Molecular mechanism for the operation of nitrogen control in cyanobacteria.

In cyanobacteria, ammonium exerts a negative regulation of the expression of proteins involved in the assimilation of nitrogen sources alternative to ammonium. In Synechococcus, mRNA levels of genes encoding proteins for nitrate and ammonium assimilation were observed to be negatively regulated by ammonium, and ammonium-regulated transcription start points were identified for those genes. The NtcA protein is a positive regulator of genes subjected to nitrogen control by ammonium. Mutants lacking NtcA exhibited only basal mRNA levels of the regulated genes, even in the absence of ammonium, indicating that NtcA exerts its regulatory action by positively influencing mRNA levels of the nitrogen-regulated genes. NtcA was observed to bind directly to the promoters of nitrogen-regulated genes, and the palindromic DNA sequence GTAN8TAC was identified as a sequence signature for NtcA-target sites. The structure of the nitrogen-, NtcA-regulated promoters of Synechococcus was determined to be constituted by a -10, Pribnow-like box in the form TAN3T, and an NtcA-binding site that substituted for the canonical -35 box.

Amino Acid Sequence↗
PubMed1994

Requirement of the regulatory protein NtcA for the expression of nitrogen assimilation and heterocyst development genes in the cyanobacterium Anabaena sp. PCC 7120.

The cyanobacterial ntcA gene encodes a DNA-binding protein that belongs to the Crp family of bacterial transcriptional regulators. In this work, we describe the isolation of an ntcA insertional mutant of the dinitrogen-fixing, heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. The Anabaena ntcA mutant was able to use ammonium as a source of nitrogen for growth, but was unable to assimilate atmospheric nitrogen (dinitrogen) or nitrate. Nitrogenase and enzymes of the nitrate reduction system were not synthesized in the ntcA mutant under derepressing conditions, and glutamine synthetase levels were lower in the mutant than in the wild-type strain. In the ntcA mutant, in response to removal of ammonium, accumulation of mRNA of the genes encoding nitrogenase (nifHDK), nitrite reductase (nir, the first gene of the nitrate assimilation operon), and glutamine synthetase (glnA) was not observed. A transcription start point of the Anabaena glnA gene (corresponding to RNAl), that has been shown to be used preferentially after nitrogen step-down, was not used in the ntcA insertional mutant. Heterocyst development (which is necessary for the aerobic fixation of dinitrogen) and induction of hetR (a regulatory gene that is required for heterocyst development) were also impaired in the ntcA mutant. These results showed that the ntcA gene product, NtcA, is required in Anabaena sp. PCC 7120 for the expression of genes encoding proteins involved in the assimilation of nitrogen sources alternative to ammonium including dinitrogen and nitrate, and that the process of heterocyst development is also controlled by NtcA.

Anabaena↗
PubMed1994

Analysis of expression of the argC and argD genes in the cyanobacterium Anabaena sp. strain PCC 7120.

A cloned DNA fragment from Anabaena sp. strain PCC 7120 that complements an arginine auxotrophic mutant from the same organism was found to include an open reading frame encoding a 427-residue polypeptide that is homologous to N-acetylornithine aminotransferase from Bacillus subtilis, Escherichia coli, and Saccharomyces cerevisiae. The gene encoding N-acetylornithine aminotransferase in bacteria has been named argD. The expression of Anabaena sp. strain PCC 7120 argD, as well as of argC, was analyzed at the mRNA level. Both genes were transcribed as monocistronic mRNAs, and their expression was not affected by exogenously added arginine. Primer extension analysis identified transcription start points for both genes which were preceded by sequences similar to that of the E. coli RNA polymerase sigma 70 consensus promoter. A second transcription start point for the argD gene that is not preceded by a sigma 70 consensus promoter was detected in dinitrogen-grown cultures.

Aldehyde Oxidoreductases↗
PubMed1994

Transfer of a genetic marker from a megaplasmid of Anabaena sp. strain PCC 7120 to a megaplasmid of a different Anabaena strain.

The 410-kb alpha megaplasmid of the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 was found to bear the nucA gene that encodes a sugar-nonspecific nuclease. That gene was mutated by insertion of a cassette that confers resistance to neomycin. The resulting strain, AMP2, was mated with a streptomycin-resistant derivative of Anabaena sp. strain PCC 7118, a strain that does not form heterocysts. Cells resistant to both neomycin and streptomycin that were derived from such matings were found to bear the neomycin resistance cassette of the donor strain in a larger megaplasmid characteristic of the recipient strain and did not form heterocysts. This is the first example of transfer of a genetic marker directly between strains of cyanobacteria in which incontrovertible physical evidence of transfer has been obtained. DNA sequences homologous to the nucA gene were present in 13 heterocyst-forming cyanobacteria that were tested but in none of six diverse unicellular strains that were examined.

Anabaena↗
PubMed1994

Nuclear localization of the PEP protein tyrosine phosphatase.

PEP is an intracellular protein tyrosine phosphatase expressed primarily by cells of hematopoietic origin that can be divided structurally into a catalytic domain and a large carboxy-terminal domain. The carboxy-terminal domain is enriched in proline, glutamic acid, serine, and threonine residues (PEST sequences) and contains a nonperfect tandem repeat sequence enriched in proline residues and a carboxy terminus enriched in basic amino acids. Here we show that PEP is diffusely expressed in lymphoid tissues, consistent with expression by many different cell types. Analysis of the PEP protein identifies a nuclear localization sequence within the extreme carboxy terminus. Transfer of 18 amino acids from the carboxy terminus of PEP to beta-galactosidase conferred nuclear localization, indicating that this sequence was sufficient for nuclear localization. Proteins enriched in PEST sequences are often rapidly degraded. However, pulse-chase analysis indicates that PEP has a half-life of greater than 5 h.

Amino Acid Sequence↗
PubMed1994

Acculturation, sexual behavior, and alcohol use among Latinas.

We explored the relationship of alcohol use to unsafe sex in Latinas. Telephone interviews were conducted with 523 currently sexually active Latinas aged 18-49 years. Only 7.5% of these women used alcohol half of the time or more prior to sex. "Regular" alcohol users had more sexual partners, but also had more experience with condom use, used condoms with primary partners as frequently as nonusers of alcohol, and used condoms more with secondary partners. While Latinas who use alcohol prior to sex more often have multiple sexual partners, alcohol use does not appear to interfere with condom use.

Acculturation↗
PubMed1993

Nitrite reductase gene from Synechococcus sp. PCC 7942: homology between cyanobacterial and higher-plant nitrite reductases.

The gene encoding nitrite reductase (nir) from the cyanobacterium Synechococcus sp. PCC 7942 has been identified and sequenced. This gene comprises 1536 nucleotides and would encode a polypeptide of 56,506 Da that shows similarity to nitrite reductase from higher plants and to the sulfite reductase hemoprotein from enteric bacteria. Identities found at positions corresponding to those amino acids which in the above-mentioned proteins hold the Fe4S4-siroheme active center suggest that nitrite reductase from Synechococcus bears an active site much alike that present in those reductases. The fact that the Synechococcus and higher-plant nitrite reductases are homologous proteins gives support to the endosymbiont theory for the origin of chloroplasts.

Amino Acid Sequence↗
PubMed1993

Homology of the N-terminal domain of the petH gene product from Anabaena sp. PCC 7119 to the CpcD phycobilisome linker polypeptide.

The complete nucleotide sequence of the petH gene encoding ferredoxin-NADP+ reductase from the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7119 has been determined. The encoded polypeptide is 136 amino acids longer than the enzyme obtained after purification to homogeneity. The extended N-terminal domain consists of 80 amino acids which shows homology to the CpcD phycobilisome linker polypeptide, through which FNR might be anchored to the thylakoid-bound phycobilisomes. A 56 amino acid interdomain fragment is found which could be a target for proteolysis.

Amino Acid Sequence↗
PubMed1993

Immunocytochemical localization of DNA in synaptonemal complexes of rat and mouse spermatocytes, and of chick oocytes.

The distribution of DNA in synaptonemal complexes of rat and mouse spermatocytes, and of chick oocytes was investigated by immunogold electron microscopy. Except for a few specific sites, DNA was not immunolocalized in the space between lateral elements of the complex. Some labeled fibrils connecting the lateral elements with the central element were observed associated with recombination nodules or near them. However, other labeled fibrils in the space between lateral elements did not appear to present any relationship to recombination nodules. The immunocytochemical approaches used here confirmed the presence of significant amounts of DNA in the lateral elements as previously indicated by preferential DNA staining methods. Furthermore, our findings support the view that recombination nodules are the site of chiasma formation.

Animals↗
PubMed1993

Molecular karyotype of related clones of Entamoeba histolytica.

The molecular karyotype of 3 clones derived from strain HM1:IMSS of Entamoeba histolytica was studied by transverse alternating field electrophoresis. 11-20 bands ranging between 0.3 and over 3 Mb were resolved. Hybridization with total DNA detected highly repetitive sequences in the slow-migrating molecules, while non-repetitive sequences were located in the intermediate and fast-migrating molecules. rDNA, tubulin, actin, cysteine proteases DNA fragments, and a variable DNA sequence (EhVR1) located the respective genes mainly in the 1.3-1.5-Mb region, although they differed in the three clones. Two-dimensional transverse alternating field electrophoresis showed that more than one high-molecular weight molecule may comigrate in a single DNA band. rDNA, and EhVR1 hybridized with slow-migrating bands in a characteristic ladder pattern. Most of the bands recognized by EhVR1 seems to be linear molecules, although exonuclease III-resistant bands also hybridized with EhVR1, suggesting the presence of circles.

Actins↗
PubMed1993

General distribution of the nitrogen control gene ntcA in cyanobacteria.

The ntcA gene from Synechococcus sp. strain PCC 7942 encodes a regulatory protein which is required for the expression of all of the genes known to be subject to repression by ammonium in that cyanobacterium. Homologs to ntcA have now been cloned by hybridization from the cyanobacteria Synechocystis sp. strain PCC 6803 and Anabaena sp. strain PCC 7120. Sequence analysis has shown that these ntcA genes would encode polypeptides strongly similar (77 to 79% identity) to the Synechococcus NtcA protein. Sequences hybridizing to ntcA have been detected in the genomes of nine other cyanobacteria that were tested, including strains of the genera Anabaena, Calothrix, Fischerella, Nostoc, Pseudoanabaena, Synechococcus, and Synechocystis.

Amino Acid Sequence↗