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S Moreno

Publications and source records attributed to S Moreno.

At least 145 records · Page 8Linked to original sources
PubMed1996

B-type cyclins regulate G1 progression in fission yeast in opposition to the p25rum1 cdk inhibitor.

The onset of S phase in fission yeast is regulated at Start, the point of commitment to the mitotic cell cycle. The p34cdc2 kinase is essential for G1 progression past Start, but until now its regulation has been poorly understood. Here we show that the cig2/cyc17 B-type cyclin has an important role in G1 progression, and demonstrate that p34cdc2 kinase activity is periodically associated with cig2 in G1. Cells lacking cig2 are defective in G1 progression, and this is particularly clear in small cells that must regulate Start with respect to cell size. We also find that the cig1 B-type cyclin can promote G1 progression. Whilst p25rum1 can inhibit cig2/cdc2 activity in vitro, and may transiently inhibit this complex in vivo, cig1 is regulated independently of p25rum1. Since cig1/cdc2 kinase activity peaks in mitotic cells, and decreases after mitosis with similar kinetics to cdc13-associated kinase activity, we suggest that cig2 is likely to be the principal fission yeast G1 cyclin. cig2 protein levels accumulate in G1 cells, and we propose that p25rum1 may transiently inhibit cig2-associated p34cdc2 activity until the critical cell size required for Start is reached.

CDC2 Protein Kinase↗
PubMed1996

Regulation of G1 progression in fission yeast by the rum1+ gene product.

Recently it has been found that B-type cyclins in fission yeast regulate the activation of the cdc2 kinase to promote the onset of both DNA replication and mitosis. cig2 is the major G1 cyclin while cdc13 is the principal mitotic cyclin. cdc13 also has an additional function in G2 phase, preventing more than one round of DNA replication per cell cycle. In opposition to these cyclins the rum1 inhibitor, a protein present exclusively in G1, prevents premature activation of the cdc2/cig2 and the cdc2/cdc13 complexes until cells have reached the critical cell size required to pass Start and initiate a new cell cycle.

Cell Cycle Proteins↗
PubMed1996

rum1: a CDK inhibitor regulating G1 progression in fission yeast.

In all eukaryotes, entry into mitosis from G2 phase is initiated by a complex of the cdc2 kinase and a B-type cyclin. It has now been shown that, in fission yeast, B-type cyclins also activate cdc2 in G1, thus governing cell-cycle commitment, as well as the onset of S phase. In this article, Karim Labib and Sergio Moreno review the evidence that ruml inhibits the kinase activity of cdc2 associated with B-type cyclins and is an important regulator o f G1 progression in fission yeast.

Journal Article↗
PubMed1996

Cytarabine therapy for progressive multifocal leukoencephalopathy in patients with AIDS.

To evaluate the efficacy and safety of intravenous cytarabine in the treatment of AIDS-associated progressive multifocal leukoencephalopathy (PML), we reviewed the charts of all human immunodeficiency virus-infected patients with PML who were seen during a 28-month period at our institution. Patients with biopsy-proven PML were offered therapy with intravenous cytarabine (2 mg/[kg.d] for 5 days every 4 weeks). The diagnosis of PML was histologically confirmed for 13 patients. The median CD4 cell count was 91 x 10(6)/L. A median of three courses of cytarabine was administered to eight patients. Two patients developed mild drug-related toxicities. Clinical and/or radiological signs of improvement were observed for three patients treated with cytarabine; no signs of improvement were noted for the untreated patients. Median survival time after the diagnosis of PML was 102 days (range, 46-220 days) for patients who received cytarabine and 60 days (range, 28-72 days) for untreated patients matched for Karnofsky scores (P = .06, logrank test). Although cytarabine is well tolerated by patients with AIDS and PML, only modest short-term clinical improvement in the conditions of patients treated with the drug has been observed, with no significant impact on survival.

AIDS-Related Opportunistic Infections↗
PubMed1996

Genetic analysis of the transcriptional arrangement of Azotobacter vinelandii alginate biosynthetic genes: identification of two independent promoters.

The study of alginate biosynthesis, the exopolysaccharide produced by Azotobacter vinelandii and Pseudomonas aeruginosa, might lead to different biotechnological applications. Here we report the cloning of A. vinelandii algA, the gene coding for the bifunctional enzyme phosphomannose isomerase-guanosine diphospho-o-mannose pyrophosphorylase (PMI-GMP). This gene was selected by the complementation for xanthan gum production of Xanthomonas campestris pv. campestris xanB-mutants, which lack this enzymatic activity. The complementing cosmid clones selected, besides containing algA, presented a gene coding for an alginate lyase activity (algL), and some of them also contained algD which codes for GDP-mannose dehydrogenase. We present here the characterization of the A. vinelandii chromosomal region comprising algD and its promoter region, algA and algL, showing that, as previously reported for P. aeruginosa, A. vinelandii has a cluster of the biosynthetic alginate genes. We provide evidence for the presence of an algD-independent promoter in this region which transcribes at least algL and algA, and which is regulated in a manner that differs from that of the algD promoter.

Alginates↗
PubMed1996

Characterization of the gene coding for GDP-mannose dehydrogenase (algD) from Azotobacter vinelandii.

Azotobacter vinelandii presents a differentiation process leading to the formation of desiccation-resistant cysts. Alginate, the exopolysaccharide produced by this bacterium, has been postulated to have a role in cyst formation. Here, we report the cloning and characterization of the A. vinelandii gene coding for the enzyme GDP-mannose dehydrogenase (algD), which is the key enzyme for alginate synthesis in Pseudomonas aeruginosa. This gene has a high degree of similarity with the algD gene from P. aeruginosa, and similar proteins seem to be involved in algD regulation in both bacteria. We show the existence of two mRNA start sites; one of these sites corresponds to a promoter transcribed by RNA polymerase containing a sigma E subunit. An A. vinelandii algD mutant which is completely impaired in alginate production and which is unable to form desiccation-resistant cells was constructed. The effects of NH4, NO3, and NaCl concentrations on algD transcription for three A. vinelandii strains producing different alginate levels were evaluated. We found a strict correlation between alginate production and algD transcription for the three strains studied; however, the effects on algD transcription under the conditions studied were different for each strain. The nitrogen source regulates algD expression in the wild-type strain.

Alginates↗
PubMed1996

Characterization of the genes coding for the putative sigma factor AlgU and its regulators MucA, MucB, MucC, and MucD in Azotobacter vinelandii and evaluation of their roles in alginate biosynthesis.

The study of the biosynthesis of alginate, the exopolysaccharide produced by Azotobacter vinelandii and Pseudomonas aeruginosa, has biotechnological and medical significance. We report here the identification of the A. vinelandii genes coding for the putative sigma factor AlgU and its negative regulators MucA and MucB through the suppression of the highly mucoid phenotype of an A. vinelandii strain by a plasmid encoding MucA and MucB. The sequences of the A. vinelandii algU, mucA, and mucB genes are highly homologous to those of the corresponding P. aeruginosa genes, AlgU shows 93% identity, and MucA and MucB are 64.4 and 63.9% identical, respectively. Forming part of the same operon as algU, mucA, and mucB, two additional genes (mucC and mucD) were identified and sequenced; the product of the former gene is homologous to ORF4 of Photobacterium sp. strain SS9, and that of the latter gene belongs to the HtrA serine protease family. Interestingly, the nonmucoid A. vinelandii UW136 had a 0.9-kb insertion within the algU gene. A strong correlation between AlgU activity and alginate production by A. vinelandii was also found, as reflected in the level of algD transcription.

Alginates↗
PubMed1996

Analysis of primer independent phosphorylase activity in potato plants: high levels of activity in sink organs and sucrose-dependent activity in cultured stem explants.

One isoform of potato (Solanum tuberosum L., cv. Spunta), type L phosphorylase (EC 2.4.1.1), exhibiting primer independent activity appears to be tuber-specific. However, this activity can also be modulated by exogenous sucrose in storage as well as in non-storage organs. Primer independent phosphorylase (PIPh) activity in microtubers and shoots of in vitro plantlets was found to be much higher than in tubers and shoots of soil-grown plants. Detached leaves of soil-grown plants showed an increase in PIPh activity as well when incubated in sucrose-containing Murashige-Skoog (MS) medium. This increase was always accompanied by a rise in starch content. The presence of metabolizable carbohydrates in the growth or incubation medium are likely to be responsible for the observed rise in PIPh activity. In vitro microtubers and micropropagated plantlet organs (shoots and roots) exhibited a correlation between measurable PIPh activity and presence of enzyme protein, as judged by Western blot analysis using anti-potato tuber type L phosphorylase antibody. Therefore, in addition, to be developmentally regulated (tuber-specific accumulation), PIPh activity associated with the tuber type L isoform might be under a form of metabolic regulation.

Isoenzymes↗
PubMed1995

Morphometric analysis of liver and kidney peroxisomes in lactating rats and their pups after treatment with the peroxisomal proliferator di-(2-ethylhexyl)phthalate.

Di-(2-ethylexyl)phthalate (DEHP) administered to adult lactating rats from delivery to weaning induces age- and organ-specific modifications of the peroxisomal morphometric parameters (VV, NA and D) in the liver and kidney of both rats and their pups. In both tissues, peroxisomal relative volume and catalase biochemical activity show a similar pattern during the development, as well as under DEHP treatment. Morphometric results suggest that two modalities of peroxisomal proliferation exist, involving: a) increases in both number and mean diameter of the organelles; b) a purely numerical increase of the organelles, accompanied by a remarkable decrement in their mean diameter. A peroxisomal population proliferated through the latter model appears unable to return to normal conditions, following treatment withdrawal. These two proliferation systems, the first implying a swelling and the latter a fragmentation of pre-existing peroxisomal profiles, are supposed to be tissue-specific in the adult animal. In particular, in the liver the 'swelling' model appears more suitable to explain peroxisome proliferation, while the kidney this process would follow the 'fragmentation' model. Immature animals might instead show in both organs intermediate features of peroxisomal proliferation modalities.

Animals↗
PubMed1995

Fever of uncertain origin in patients infected with the human immunodeficiency virus.

To assess the frequency and etiology of fever of uncertain origin (FUO) in patients infected with the human immunodeficiency virus (HIV) and to evaluate the yield of diagnostic procedures used in their evaluation, we reviewed the clinical charts of all patients admitted to an AIDS unit during a 15-month period. FUO was defined by the endurance of a fever (temperature, > 38.2 degrees C) for at least 4 weeks before admission and the uncertainty of diagnosis after 3 days, despite appropriate investigation. Of 580 patients evaluated, 50 (8.2%) had FUO. Patients with FUO were at advanced stages of HIV infection (median CD4+ cell count, 71/mm3), and a vast majority (84%) had previously diagnosed AIDS. A cause of the fever was identified for 44 patients (88%), and infections accounted for 82% of all cases. Tuberculosis (42%), visceral leishmaniasis (14%), and disseminated Mycobacterium avium complex infection (14%) were the most frequent diagnoses. Examination of lymph node aspirates, bone marrow biopsy, and culture of clinical specimens for mycobacteria were the procedures with the highest diagnostic yield. Among 6 patients with fever of no identified etiology, 4 died while febrile, and fever was self-limited in the other 2 patients. FUO is common among patients with advanced HIV infection. Since a cause, usually infection, can be identified in most patients, long-lasting fever should not be attributed to HIV itself.

Adult↗
PubMed1995

Infections caused by erythromycin-resistant Streptococcus pneumoniae: incidence, risk factors, and response to therapy in a prospective study.

To evaluate the incidence and the significance of resistance to erythromycin among clinical isolates of Streptococcus pneumoniae, we identified and prospectively followed all hospitalized patients in a 27-month period who had the organism isolated from any clinical sample. Patients who had an infection caused by pneumococci resistant to erythromycin (minimum inhibitory concentration, > 1 microgram/mL) were compared to those with infections caused by erythromycin-susceptible organisms. The incidence of erythromycin resistance among pneumococci doubled over the study period (from 7.6% in 1988 to 15.2% in 1992). Most strains (94%) showed resistance to multiple antibiotics, including other macrolides. By multivariate analysis, an age of < 5 years and nosocomial acquisition of the infection were independent risk factors for erythromycin resistance. Among patients with pneumococcal pneumonia caused by erythromycin-resistant organisms, 9 patients treated with third-generation cephalosporins were cured, while therapy with erythromycin failed for 2 of the 6 patients to whom it was administered. The rapid and significant increase of erythromycin resistance among clinical isolates of S. pneumoniae points to the need for routine surveillance of pneumococcal resistance.

Adolescent↗
PubMed1995

Comparative study of mupirocin and oral co-trimoxazole plus topical fusidic acid in eradication of nasal carriage of methicillin-resistant Staphylococcus aureus.

Mupirocin is a topically applied drug that is very active in the eradication of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA). However, studies designed to compare mupirocin treatment with other antimicrobial regimens are lacking. We therefore conducted an open, prospective, randomized, controlled trial to compare the efficacy and safety of mupirocin versus those of oral co-trimoxazole plus topical fusidic acid (both regimens with a clorhexidine scrub bath) for the eradication of MRSA from nasal and extranasal carriers of MRSA. The eradication rates with mupirocin and co-trimoxazole plus fusidic acid at 2, 7, 14, 21, 28, and 90 days were 93 and of 93, 100 and 100, 97 and 94, 100 and 92, 96 and 95, and 78 and 71%, respectively, for nasal carriage. At 7, 14, and 28 days the eradication rates for extranasal carriage by the two regimens were 23 and 74, 83 and 76, and 45 and 69%, respectively. The efficacies and safety of both regimens were similar. The MRSA isolates were not resistant to the study drugs either at the baseline or at follow-up. These results suggest that mupirocin and co-trimoxazole plus fusidic acid, both used in conjunction with a chlorhexidine soap bath, are equally effective and safe for the eradication of MRSA from nasal and extranasal MRSA carriers. Mupirocin was easier to use but was more expensive.

Administration, Oral↗
PubMed1995

Immunocytochemical localization of catalase in the central nervous system of the rat.

Catalase is a marker for peroxisomes, which are ubiquitous cytoplasmic organelles. Although the distribution and features of peroxisomes are well known in liver and kidney, these organelles have been rarely studied in neural tissues. Catalase is an important scavenging enzyme against reactive oxygen species, as it removes H2O2 produced during metabolic processes. Reactive oxygen species are involved in a number of brain lesions and in brain aging. We investigated the distribution of catalase in rat central nervous system by means of a newly developed immunocytochemical procedure for signal enhancement, using an affinity-purified polyclonal antiserum. The data show that catalase immunoreactivity is present in all neural cells, both neuronal and glial, albeit at different concentrations. Among glial cells, ependymal cells and tanycytes of the third ventricle and the median eminence show the most intense immunoreaction; positivity is also found in oligodendrocytes and astrocytes. In general, neurons in the brainstem are relatively more immunoreactive than those in the forebrain although, within these respective brain regions, there are areas with low and high staining intensity. Moreover, within the same area, certain types of neuron appear more immunoreactive than others. The cell bodies in the septal nuclei, pallidum, reticular thalamic nucleus, mesencephalic nucleus of the trigeminal nerve, Deiter's nucleus, locus ceruleus, cranial and spinal motor nuclei, and the Golgi cells of the cerebellar cortex are among the most densely stained neurons. Catalase immunoreactivity of the cell bodies, which presumably is proportional to catalase content, appears to be only partially correlated with cell size or type of neurotransmitter used in the nerve endings; it is likely that other unknown parameters regulate the abundance of the enzyme. In many cases, highly immunoreactive cells correspond to neurons known to be resistant to ischemia-reperfusion injury, whereas weakly stained cells correspond to neurons that are more susceptible to ischemic damage. The amount of catalase may be critical for a protective effect against oxidative stress under pathological conditions, such as ischemia-reperfusion injury.

Animals↗
PubMed1995

Interaction of cdc2 and rum1 regulates Start and S-phase in fission yeast.

The p34cdc2 kinase is essential for progression past Start in the G1 phase of the fission yeast cell cycle, and also acts in G2 to promote mitotic entry. Whilst very little is known about the G1 function of cdc2, the rum1 gene has recently been shown to encode an important regulator of Start in fission yeast, and a model for rum1 function suggests that it inhibits p34cdc2 activity. Here we present genetic data suggesting that rum1 maintains p34cdc2 in a pre-Start G1 form, inhibiting its activity until the cell achieves the critical mass required for Start, and find that in the absence of rum1 p34cdc2 has increased Start activity in vivo. It is also known that mutation of cdc2, or overexpression of rum1, can disrupt the dependency of S-phase upon mitosis, resulting in an extra round of S-phase in the absence of mitosis. We show that cdc2 and rum1 interact in this process, and describe dominant cdc2 mutants causing multiple rounds of S-phase in the absence of mitosis. We suggest that interaction of rum1 and cdc2 regulates Start, and this interaction is important for the regulation of S-phase within the cell cycle.

CDC2 Protein Kinase↗
PubMed1995

MR imaging and CT of central nervous system tuberculosis in the patient with AIDS.

CNS TB represents a disease that complicates AIDS with an increasing incidence in endemic areas as well as in developed countries in those patients who have some risk factors such as intravenous drug abuse. Although TB infection of the CNS in AIDS patients may follow a rapidly progressive course, the imaging findings otherwise are similar to those of the nonimmunosuppressed population. Meningeal enhancement, hydrocephalus, parenchymal granulomata, and infarcts are seen frequently and are often observed in combination with one another. Nevertheless, the differential diagnosis in AIDS patients must include other opportunistic infections and primary or metastatic lymphoma of the CNS. Spinal TB usually is seen in the form of epidural abscess secondary to tuberculous spondylitis, although it may be seen in isolation of spinal column involvement. The differential diagnosis includes spinal lymphoma or pyogenic abscess formation. Radiculomyelitis or isolated spinal cord tuberculomata are much less frequently observed and can be suspected on imaging only if there is concomitant evidence of the classic findings of intracranial TB.

AIDS-Related Opportunistic Infections↗