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M E Alvarez

Publications and source records attributed to M E Alvarez.

At least 37 records · Page 2Linked to original sources
PubMed1994

Isolation and structure elucidation of two new calpain inhibitors from Streptomyces griseus.

Two new peptides, a diketopiperazine of N-methyltyrosine (1) and a tetrapeptide containing N-methyltyrosine (2), were isolated from an actinomycete strain Streptomyces griseus. These compounds inhibit the enzyme calpain in the micromolar range and were characterized on the basis of spectroscopic analysis, amino acid analysis and sequencing. The structure of the tetrapeptide N-methyltyrosyl-N-methyltyrosyl-leucyl-alanine (2), was also confirmed by total synthesis.

Calpain↗
PubMed1993

The 59-kDa polypeptide constituent of 8-10-nm cytoplasmic filaments in Neurospora crassa is a pyruvate decarboxylase.

The fungus Neurospora crassa harbors large amounts of cytoplasmic filaments which are homopolymers of a 59-kDa polypeptide (P59Nc). We have used molecular cloning, sequencing and enzyme activity measurement strategies to demonstrate that these filaments are made of pyruvate decarboxylase (PDC, EC 4.1.1.1), which is the key enzyme in the glycolytic-fermentative pathway of ethanol production in fungi, and in certain plants and bacteria. Immunofluorescence analyses of 8-10-nm filaments, as well as quantitative Northern blot studies of P59Nc mRNA and measurements of PDC activity, showed that the presence and abundance of PDC filaments depends on the metabolic growth conditions of the cells. These findings may be of relevance to the biology of ethanol production by fungi, and may shed light on the nature and variable presence of filament bundles described in fungal cells.

Amino Acid Sequence↗
PubMed1992

Molecular cloning of a gene (cfp) encoding the cytoplasmic filament protein P59Nc and its genetic relationship to the snowflake locus of Neurospora crassa.

P59Nc is a 59-kD polypeptide associated with 8-10-nm diameter cellular filaments in normal Neurospora crassa strains. Abnormally sized and shaped bundles of these structures are present in N. crassa strains carrying mutations at the locus sn (snowflake). By using molecular cloning and restriction fragment length polymorphism (RFLP) segregation analysis strategies we show here that sn is not the genetic locus of P59Nc. Several P59Nc cDNAs were cloned from a N. crassa lambda GT11 library after immunoscreening with specific polyclonal anti-P59Nc antibodies. Additional longer cDNAs were obtained from a N. crassa cDNA-lambda ZAP library. When used as probes in Southern blots of total DNA from wild-type strains, multicent-2 (a multiple mutant strain), and snowflake mutants, the P59Nc cDNAs revealed comparable patterns of hybridizing bands for all of the restriction enzymes tested. Analysis of segregation of BclI and ClaI RFLPs, detected in the genomic region of the P59Nc gene (locus cfp: cellular filament polypeptide), among a set of strains designed for RFLP mapping, or among selected progeny of crosses involving a snowflake parent, respectively, indicate that (i) there is in N. crassa a single cfp locus positioned on the right arm of linkage group VII between the locus for and the proximal breakpoint of the translocation T(VII----I)5936; (ii) the sn mutations in the centromere region of chromosome I do not represent translocations of cfp; and (iii) the snowflake mutants possesses a normal copy of the P59Nc gene on their chromosomes VII.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Antibodies against the 59 kDa polypeptide of the N. crassa 8-10 nm filaments immunodetect a 59 kDa polypeptide in specialized rat epithelial cells.

P59Nc is a polypeptide associated with bundles of cytoplasmic and nuclear filamentous structures of 8-10 nm of diameter in Neurospora crassa cells. It is immunologically unrelated to both higher and lower eucaryotic tubulin and actin proteins and is detected weakly by the anti IFA monoclonal antibody. We analyze here the immunological relationship between P59Nc and intermediate filament (IF) mammalian proteins by using anti P59Nc, anti keratin, anti vimentin and anti IFA antibodies. Anti P59Nc antibodies detected a 59 kDa polypeptide from rat and bovine tissues which copurifies with polypeptides of the IF family. Neither P59Nc nor the 59 kDa rat polypeptide were recognized by anti keratin or anti vimentin antibodies. Immunostaining of rat tongue sections with anti P59Nc antibodies showed that the 59 kDa rat polypeptide is present in the cortical cytoplasm of suprabasal epithelial cells. The results indicate that P59Nc shares common antigenic determinants with a still uncharacterized 59 kDa polypeptide from mammalian tissues which have extractability and immunological properties similar to those of IF polypeptides and shows a tissular distribution and a cellular localization similar but distinguishable from keratins.

Animals↗
PubMed1990

A polypeptide of 59 kDa is associated with bundles of cytoplasmic filaments in Neurospora crassa.

Complex arrangements of filamentous structures have been isolated from vegetative cells of the fungus Neurospora crassa. They were enriched by differential centrifugation and purified by permeation chromatography. The filamentous structures are made up of units of 8-10 nm diameter and were isolated in bundles of up to six to nine units. The main constituent of these structures is a polypeptide with an apparent molecular mass of 59 kDa (P59Nc), which represents 4-5% of the total N. crassa proteins. The filamentous structures are cold-stable and are not affected by high-ionic-strength solutions or by the presence of 10 mM-EDTA or 1% (w/v) Triton X-100; they were disassembled by raising the pH of the solution or by using Tris-based buffers. The disassembled form assembled into structures sedimentable at 105,000 g after dialysis against the isolation buffer. The sedimentable structures were organized in the form of regular aggregates of 42-45 nm polypeptides and reacted weakly with anti-IFA, a monoclonal antibody which recognizes an epitope common to many of the higher-eukaryote intermediate-filament polypeptides. Immunofluorescence examination of wall-digested hyphae of N. crassa using affinity-purified antibodies prepared against P59Nc showed immunostaining of abundant filamentous and dot-shaped structures distributed in the cytoplasm.

Cytoskeleton↗
PubMed1987

Imipenem/cilastatin therapy of infections in cancer patients.

Imipenem/cilastatin was administered during 153 febrile episodes occurring in cancer patients and the response rate was 68%. Considering only documented infections the response rate was 71%. Patients who received imipenem as initial therapy had a higher response rate than patients who received it after failing other antibiotics (77% versus 68%). The overall response rates for septicemias and pneumonias were 75% and 58%. Among the 57 gram-negative infections 77% responded, but the response rate was substantially higher if imipenem was used as initial therapy (94% versus 69%). The poorest response rate was observed when imipenem was given as secondary therapy for Pseudomonas infections (50%), but most of these patients had failed to respond to other appropriate antibiotics. The only serious side effect was seizures which occurred in ten patients, although eight of them had other predisposing factors. Imipenem appears to be a useful antibiotic for treatment of infections, even in neutropenic cancer patients.

Adolescent↗
PubMed1986

In-vitro activity of cefpirome (HR-810), WIN-49375, BMY-28142 and other antibiotics against nosocomially important isolates from cancer patients.

The activity of three new antimicrobial agents [cefpirome (HR 810), BMY 28142, WIN 49375], and imipenem was compared to that of four currently available agents, ceftazidime, aztreonam, timentin and piperacillin, against 253 bacterial isolates from cancer patients. The activity of all four agents not yet in clinical use at our institution was significantly greater than that of the four antibiotics already in use.

Anti-Bacterial Agents↗
PubMed1986

In-vitro activity of Sch 34343, a new penam, against gram-positive isolates from cancer patients.

The in-vitro activity of Sch 34343, a new penam antibiotic, was tested against 257 Gram-positive isolates from cancer patients, and compared with that of imipenem and amifloxacin. Sch 34343 was extremely active against beta-haemolytic streptococci (Lancefield groups A, B and G) with MIC90s ranging from 0.025 to 0.05 mg/l. It was also active against methicillin-susceptible Staphylococcus aureus and had variable activity against coagulase-negative staphylococci. MIC90 for Listeria monocytogenes was 0.78 mg/l and 84% of enterococcal isolates were inhibited by 6.25 mg/l.

Anti-Bacterial Agents↗
PubMed1986

Imipenem/cilastatin as secondary therapy for infections in cancer patients.

Imipenem/cilastatin was used to treat 68 documented infections in patients who had failed to respond to other antibiotic regimens. The overall response rate was 68% and was higher among patients in whom the infecting organism could be identified (71% vs. 60%). The response rates were 73% in the 37 cases of septicaemia and 54% in the 13 cases of pneumonia. The response rate in Gram-negative bacillary infections was 69%, but was 50% for those caused by Pseudomonas aeruginosa. The response rate did not correlate with patients' neutrophil counts, but was higher if the neutrophil count increased during therapy than if it decreased (86% vs. 48%, P = 0.001). The drug was well tolerated but one patient developed seizures. Imipenem/cilastatin appears to be a useful antibiotic as single agent therapy for most infections in cancer patients.

Adolescent↗
PubMed1986

Imipenem-cilastatin as initial therapy for febrile cancer patients.

Imipenem-cilastatin was used to treat 79 febrile episodes in 71 cancer patients, most of whom had neutropenia. The overall response rate was 67%, and 76% of the 45 documented infections responded. The response rates for septicemias and pneumonias were 79 and 62%, respectively. Only 1 of the 17 infections caused by gram-negative bacilli failed to respond to this therapy. The most common side effects were skin rash, nausea, and diarrhea. Eight superinfections were detected during therapy.

Adult↗
PubMed1986

Comparative in vitro activity of cefpirome and other antimicrobial agents against isolates from cancer patients.

Cefpirome and six other antimicrobial agents were tested against 884 blood culture isolates from cancer patients. Cefpirome was highly active against aerobic gram-negative bacilli including Acinetobacter spp., and the Enterobacteriaceae. Only imipenem was more active than cefpirome against Pseudomonas aeruginosa. Cefpirome was also extremely active against beta-hemolytic streptococci and methicillin-susceptible staphylococci.

Anti-Bacterial Agents↗
PubMed1986

In vitro activity of SCH-34343, a new penam, and other antimicrobial agents against clinical isolates from cancer patients.

The in vitro activity of SCH-34343, a new penam antibiotic, was tested against gram-positive and gram-negative isolates from cancer patients, and compared to that of 7 other antimicrobial agents. SCH-34343 was extremely active against the Enterobacteriaceae with MIC90 ranging from 0.39 to 6.25 micrograms/ml for Citrobacter spp., Enterobacter spp., Escherichia coli, Klebsiella spp., Proteus spp. and Serratia marcescens. It was less active against Acinetobacter spp. (MIC90 6.25-12.5 micrograms/ml) and had poor activity against Pseudomonas aeruginosa. Among gram-positive isolates group A and G beta-hemolytic Streptococci were extremely susceptible to SCH-34343 (MIC90 0.025-0.05 micrograms/ml). Good activity against methicillin-susceptible coagulase-positive and coagulase-negative Staphylococci and Listeria monocytogenes, and moderate activity against Enterococci was also seen.

Anti-Bacterial Agents↗
PubMed1985

Dengue and hepatic failure.

Dengue hemorrhagic fever/dengue shock syndrome is a serious manifestation of dengue fever, which is observed predominantly in the tropical regions of the West Pacific and in Southeast Asia and is associated with secondary infections, mainly in children under age 15. A concomitant microangiopathic coagulopathy has been described; moreover, encephalopathy and even Reye's syndrome have been rarely reported. This report describes a 51-year-old man with secondary dengue infection who presented with clinical evidence of severe hepatitis, encephalopathy, cranial nerve palsy, and microangiopathic coagulopathy and who had a favorable outcome. A careful surveillance for the occurrence of secondary dengue in the Western Hemisphere is proposed, and dengue is suggested as a diagnostic possibility in obscure febrile illnesses presenting as either hepatitis, encephalopathy, or coagulopathy in places in which the mosquito vector, Aedes aegypti, is present.

Cranial Nerve Diseases↗
PubMed1985

Influence of nitrogen source and growth status on glutamine synthetase and glutamate synthase activity in Mycobacterium avium.

An investigation was made of the activity of glutamine synthetase and glutamate synthase from batch-cultured cells of Mycobacterium avium. The bacteria were grown in medium with ammonium chloride concentrations of 0, 0.1, 0.25, 1, 5, or 25 mumol/mL or with glutamine at 0.1 or 1 mumol/mL. The specific activity of the two enzymes was determined at 0, 22, 45, and 70 h of incubation. Regardless of the ammonia concentration in the medium, glutamate synthase specific activity was two to five times higher in extracts from elongating cells, incubated 22 h, than in those from shortened cells, incubated 45 or 70 h. In contrast, there was no apparent difference in glutamine synthetase specific activity with regard to culture age; however, glutamine synthetase specific activity varied inversely with the concentration of ammonium chloride in the medium. Cells grown in glutamine had high activity of glutamine synthetase.

Ammonium Chloride↗
PubMed1984

Glutamine synthetase from Mycobacterium avium.

Mycobacterium avium was previously shown to be dependent upon ammonia or glutamine as a nitrogen source. In an effort to assess the physiology of ammonia assimilation by M. avium, a characterization of its glutamine synthetase was performed. The enzyme from M. avium was purified by streptomycin sulfate treatment, ammonium sulfate precipitation, and affinity chromatography. The enzyme was unusual in that it had a pH optimum of 6.4 and maximum enzyme activity was obtained between 50 and 60 degrees C as shown by the transferase assay. The glutamine synthetase activity from batch-cultured cells decreased with increasing concentration of ammonium chloride in the range of 0.25-5 mumol/mL of medium, which demonstrated a response to environmental supply of a nitrogen source. The mycobacterial enzyme was similar to the other bacterial glutamine synthetases in terms of molecular weight and sedimentation coefficient which were 600 000 and 19.5 S, respectively, and enzyme activity was lost by treatment with a glutamate analog, methionine sulfoximine. The isoelectric point was, however, pH 4.5. Treatment of the enzyme with snake venom phosphodiesterase resulted in an increase in specific activity. AMP was released by the phosphodiesterase treatment, thus demonstrating that M. avium glutamine synthetase was regulated by adenylylation modification.

Ammonium Chloride↗
PubMed1982

Effects of chlorine concentration on the structure of poliovirus.

Chlorine concentrations below 0.8 mg/liter inactivated poliovirus without causing separation of the viral components. These results indicate that the release of RNA from the capsids is the result, not the cause, of virus inactivation by chlorine.

Centrifugation, Density Gradient↗
PubMed1982

Mechanisms of inactivation of poliovirus by chlorine dioxide and iodine.

Chlorine dioxide and iodine inactivated poliovirus more efficiently at pH 10.0 than at pH 6.0. Sedimentation analyses of viruses inactivated by chlorine dioxide and iodine at pH 10.9 showed that viral RNA separated from the capsids, resulting in the conversion of virions from 156S structures to 80S particles. The RNAs release from both chlorine dioxide- and iodine-inactivated viruses cosedimented with intact 35S viral RNA. Both chlorine dioxide and iodine reacted with the capsid proteins of poliovirus and changed the pI from pH 7.0 to pH 5.8. However, the mechanisms of inactivation of poliovirus by chlorine dioxide and iodine were found to differ. Iodine inactivated viruses by impairing their ability to adsorb to HeLa cells, whereas chlorine dioxide-inactivated viruses showed a reduced incorporation of [14C]uridine into new viral RNA. We concluded, then, that chlorine dioxide inactivated poliovirus by reacting with the viral RNA and impairing the ability of the viral genome to act as a template for RNA synthesis.

Adsorption↗