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Biomedical subjects

M Russo

Publications and source records attributed to M Russo.

At least 163 records · Page 9Linked to original sources
PubMed1991

Mutagenesis of the cyanobacterium Spirulina platensis by UV and nitrosoguanidine treatment.

The production of Spirulina platensis cells resistant to 8-azaguanine or beta-(2-thienyl)-DL-alanine following mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and UV-irradiation is described. The conditions for the mutagenesis were determined by monitoring cell viability and the appearance of the two types of mutants as a function of the stage of growth of the tricomes and the length and the conditions of the treatment. The optimal conditions for UV and MNNG mutagenesis were found to be 1-3 min irradiation and 30 min incubation with 50 micrograms MNNG/ml of tricomes derived from cultures entering stationary phase sonicated for 10 s and 5 s respectively. Under these conditions beta-(2-thienyl)-DL-alanine-resistant mutants appeared at a frequency greater than or equal to 10(-4) and greater than or equal to 10(-5) following UV- and MNNG-mutagenesis, respectively. Mutants resistant to 8-azaguanine were found at a frequency approx. 10(-5) only after MNNG mutagenesis. A few chlorate-resistant mutants were also obtained following UV treatment.

Cyanobacteria↗
PubMed1991

Activation signals leading to proliferation of normal and leukemic CD3+ large granular lymphocytes.

The activation signals leading to proliferation of normal and leukemic CD3+ large granular lymphocytes (LGL) were studied in vitro. Anti-CD3 monoclonal antibody (MoAb) alone (P less than .01) and recombinant interleukin-2 (IL-2) alone (P less than .01) caused significant stimulation of peripheral blood mononuclear cells (PBMC) from four CD3+ LGL leukemia patients, as measured in a 3H-thymidine incorporation assay. Recombinant interleukin-4 (IL-4) alone had no effect (P = .11). The combination signals of anti-CD3 MoAb and either IL-2 or IL-4 produced a proliferative response greater than anti-CD3 MoAb alone (P less than .01) or lymphokine alone (P less than .01). Leukemic LGL, purified by two-color sorting, were subsequently activated by anti-CD3 MoAb and IL-2 and assessed for DNA content by viable Hoechst No. 33342 (HO) staining. Results of these studies demonstrated that leukemic LGL were stimulated directly by anti-CD3 MoAb and IL-2, with the percentage of cells in cell cycle (S + G2/M) ranging from 16% to 72%. Normal CD3+ LGL were also stimulated to enter the cell cycle by anti-CD3 and IL-2. These results show that leukemic LGL proliferate in vitro after activation through the T-cell receptor and/or lymphokine.

Antibodies, Monoclonal↗
PubMed1991

Is TNF alpha involved in early susceptibility of Trypanosoma cruzi-infected C3H/He mice?

Early wasting and subsequent mortality may occur in mice of some inbred strains following infection with Trypanosoma cruzi. It was hypothesized that TNF alpha/cachectin might be involved in this process. Thus, sera collected from mice of strains differing in their susceptibility or resistance to Trypanosoma cruzi infection were checked for the presence and level of TNF alpha, a cytokine able to exert acute toxic effects. C3H/HeJ or C3H/HePas (susceptible), BALB/c (intermediate) and C57BL/6 (resistant) mice were infected with the CL or Colombian strain of Trypanosoma cruzi, and TNF activity was measured in the sera during the acute phase of the infection. Only serum collected from infected C3H/He mice contained TNF activity. However, TNF activity could be measured in serum of all strains, following LPS infection, indicating that the infection was able to prime macrophages of infected mice to secrete TNF alpha. The TNF alpha/cachectin release in the sera of C3H mice may play a role in the early wasting and death of these mice after Trypanosoma cruzi infection.

Acute Disease↗
PubMed1991

De novo generation of cymbidium ringspot virus defective interfering RNA.

Nicotiana clevelandii plants were inoculated with cymbidium ringspot tombusvirus RNA synthesized in vitro, after which further passages were made by sap inoculation. During the third passage, low Mr RNA species appeared which had the characteristics of deletion mutants of genomic RNA. Sequence analysis of several of these defective interfering RNAs suggested a possible evolution of smaller from larger molecules. Computer-generated secondary structures of sequences surrounding recombination sites were extensive and stable and these sites occurred in interior or hairpin loops, thus providing a possible explanation for discontinuous RNA transcription and the formation of deletions in genomic RNA.

Base Sequence↗
PubMed1990

[Prevention of congenital toxoplasmosis].

Toxoplasma gondii can be transmitted from mother to fetus during primary maternal infection acquired after or, possibly, slightly before conception. The incidence of congenital infection is highest in the third trimester, while severity is greatest when maternal infection is acquired during the first trimester. About 50 per cent of mothers who acquire the infection during gestation, if not treated, will give birth to infected infants. Incidence of congenital toxoplasmosis varies from 0.5 to 6.5 cases per 1000 live births. Serologic screening before or very early in pregnancy is required to identify seronegative women who are at risk to acquire the infection during pregnancy. Prevention of congenital toxoplasmosis is obtained by educating pregnant women at risk about how to prevent the infection and by diagnosing acute infection of mother. Every mother who demonstrates seroconversion for toxoplasmosis during pregnancy has to be treated as soon as possible. Therapy is based on spiramycin that achieves high concentrations in the placenta; if the fetus is infected pyrimethamine plus sulphonamides are administered since fourth month. Chemotherapy of the infected pregnant mother reduces the incidence of congenital toxoplasmosis and the severity of the disease in the newborn. Intrauterine infection can be detected by fetal blood sampling, by amniocentesis and ultrasound examination; prenatal diagnosis is mandatory if an abortion is being considered.

Adult↗
PubMed1990

Studies on inflammatory response induced by Ehrlich tumor in mice peritoneal cavity.

In the present study we investigated the inflammatory response induced by the inoculation of Ehrlich tumor cells (EAT) into the peritoneal cavity of mice. It was found that after inoculation of 10(3) EAT cells, the number of peritoneal leukocytes remained unchanged till the sixth day. Subsequently, the number of cells increased as a consequence of tumor growth. EAT cells did not induce influx of PMN leukocytes till six days after tumor implantation, but a significant influx was observed on the tenth day. Inoculation of the tumor cells did not induce production of H2O2 by peritoneal cells at any time examined and induced low levels of macrophage spreading only until the third day after tumor implantation but not later on. The levels of thromboxane in the peritoneal cavity were not affected by the presence of the tumor, whereas prostaglandin E2 levels were significantly increased at all times examined. The biological significance of these results on the evolution and escape of the tumor from host defense mechanisms is under investigation.

Animals↗
PubMed1990

The stage-specific 90-kilodalton surface antigen of metacyclic trypomastigotes of Trypanosoma cruzi.

The 90-kDa antigen, previously identified by the monoclonal antibody 1G7 to be a stage-specific surface protein of metacyclic trypomastigotes of Trypanosoma cruzi, has been further characterized in this study. Experiments of metabolic labeling with [35S]methionine, [2H]mannose and [3H]galactose revealed that the 90-kDa antigen is the main glycoprotein synthesized by metacyclic forms (G strain). Through pulse-chase experiments with [35S]methionine-labeled metacyclic trypomastigotes, it was found that the antigen is synthesized as a 75-kDa precursor polypeptide that is rapidly processed to the mature 90-kDa molecule. When metacyclic trypomastigotes were treated with tunicamycin, the production of 90-kDa antigen was greatly diminished, and the 75-kDa species, which was also expressed on the cell surface, accumulated. Concanavalin A bound strongly to the 90-kDa antigen, but failed to recognize the 75-kDa polypeptide. Treatment of neuraminidase had no effect on the 90-kDa antigen, whereas digestion by endoglycosidase H generated a polypeptide of 82 kDa. Altogether these data indicate that the 90-kDa antigen is a glycoprotein containing N-linked oligosaccharide side chains of the high-mannose type. The 90-kDa glycoprotein may be involved in the process of host cell invasion, since the internalization of metacyclic forms into Vero cells was partially inhibited by monoclonal antibody 1G7.

Acetylglucosaminidase↗
PubMed1990

Inhibition of Ehrlich ascites tumor in vivo by PAF-antagonists.

Several lines of evidence support that PAF modulates the inflammatory and immune responses, and that tumors may inhibit both these processes. In the present study we analysed the effect of PAF antagonists on the growth of Ehrlich Ascites Tumor (EAT) in vivo. Mice were inoculated intraperitoneally with 1 x 10(3) EAT cells and the tumor growth evaluated by counting the number of peritoneal cells, 1,6 and 10 days after tumor implantation. BN 52021 was administered intraperitoneally, intravenously or subcutaneously once or twice a day, at 1.0, 2.5, 5.0 and 20.0 mg/kg. Control animals received 0.1 ml of the vehicle in the same schedule. It was found that i.p. and i.v. administration of BN 52021 (5 mg/kg, twice a day) significantly inhibited EAT growth (80.8% and 56.0% respectively). Other routes and doses were less effective. Another PAF antagonist, SRI 63441 (5 mg/kg, i.p., twice a day) also inhibited EAT growth (80.4%). The BN 52021 added to EAT cells in culture, at concentration of 10(-3) and 10(-4) M, did not affect the viability and proliferation of tumors cells. In an attempt to understand the mechanism of this inhibition, we analyzed the peritoneal macrophages for spreading ability and H2O2 release. It was found that 24 h after tumor implantation there was an increase in the spreading ability of peritoneal macrophages (75%) and that, as the tumor grew, the spreading index fell to control levels ( less than 10%). (5 mg/kg/twice a day) the spreading remained elevated (50-60%) at all the times examined. Release of H2O2, measured by horseradish peroxidase-phenol red oxidation, was below detectable levels throughout tumor growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Sequence analysis of cymbidium ringspot virus satellite and defective interfering RNAs.

The nucleotide sequences of cloned cDNA copies of satellite and defective interfering (DI) RNAs of cymbidium ringspot virus were determined. DI RNA is 499 nucleotides long and is composed of six stretches of sequence derived from CyRSV genomic RNA. Four of these stretches share common 5' sequences and the 5' and 3' ends are identical to those of genome RNA. Satellite RNA is 621 nucleotides long. In some regions the sequence is very similar (60% to 100% identical) to genomic RNA. A consensus sequence is proposed to be involved in the replication of genomic, DI and satellite RNAs.

Base Sequence↗
PubMed1990

Synthesis of infectious RNA from full-length cloned cDNA to RNA of cymbidium ringspot tombusvirus.

A full-length DNA copy of cymbidium ringspot virus RNA was cloned downstream of a phage T7 promoter. In vitro transcripts had no extra nucleotides at the 3' terminus, and a 5' end likely to be precisely as in genomic RNA. Transcripts were infective when inoculated into test plants. Northern blots from inoculated plants revealed the presence of genomic and subgenomic RNAs, but not of satellite RNA. Virus particles isolated from infected plants had the same outward aspect and size as those of the wild-type virus and were decorated by an antiserum to CyRSV in immune electron microscopy tests.

Base Sequence↗
PubMed1989

[Alcoholic liver diseases and their treatment].

Alcohol abuse is widespread and alcoholic liver disease represents a major medical and social problem. The spectrum of alcoholic liver injury is currently grouped into three clinical forms: fatty liver, alcoholic hepatitis and cirrhosis. The rational management of alcoholic liver disease can be divided in non-specific therapy and in specific treatment. The most important aspect of non-specific therapy is cessation of alcohol consumption: the abstinence diminishes symptoms and improves signs, and significantly increases survival. As to specific treatment, a number of controlled clinical trials of various forms of therapy have been carried out. Steatosis is spontaneously reversible after cessation of alcohol consumption, and therefore no treatment is necessary. For hepatitis, a number of protocols have been studied with both low and high doses of corticosteroids, cyanidanol, penicillamine, synthetic thyroid antagonists, hormones, and amino acids. Results have been negative, disappointing, or contradictory. In cirrhosis, corticosteroids and colchicine have been used: the former were ineffective while clinical and histological improvement as well as reduced mortality were obtained with the latter. Especially interesting results were registered after treatment with polyunsaturated phosphatidylcholine which has been used for steatosis, acute hepatitis and cirrhosis with good clinical, histological, and biohumoral findings.

Adrenal Cortex Hormones↗
PubMed1989

Immunodiagnosis of acute leukemia displaying ectopic antigens: proposal for a classification of promiscuous phenotypes.

The nature of the blast cells in 163 cases of acute leukemia was investigated by immunophenotyping, with particular emphasis on the expression of "ectopic" surface membrane structures. Although no antigen included in our panel except CD3 revealed absolute lineage restriction, immunological typing allowed a definite characterization of blast cells in more than 90% of cases. Four groups of patients were identified (A, B, C, D) with different degrees of antigen ectopic expression. We classified as group A leukemias (74%) those expressing conventional antigenic patterns, in absence of cross-lineage markers. Samples classified as group B (18%) showed a single ectopic membrane specificity, apparently discordant with the overall composite phenotype; such a "low-grade deviation" did not prevent a definite immunodiagnosis. Pattern C specimens (5%) revealed a promiscuous coexpression of markers related to different lineages (biphenotypic leukemias), whereas group D included unclassifiable phenotypes, characterized by no antigen or DR-only expression. Our findings suggest the possibility of interpreting complex phenotypic constellations of membrane markers in a consistent and logical manner.

Acute Disease↗
PubMed1989

Nucleotide sequence of the 3'-terminal region of cymbidium ringspot virus RNA.

The nucleotide sequences of cDNA clones corresponding to 2569 nucleotides from the 3' end of cymbidium ringspot tombusvirus (CyRSV) RNA were determined. This region contains three open reading frames giving rise to three predicted protein products, two of which had been identified in previous studies. The 3' non-coding region is 351 nucleotides long. The amino acid sequence of CyRSV coat protein has striking similarities with that of tomato bushy stunt tombusvirus, particularly in the S domain. No homology was found between the protein encoded by the second largest open reading frame and the corresponding product of other plant viruses.

Amino Acid Sequence↗
PubMed1989

Susceptible mice present higher macrophage activation than resistant mice during infections with myotropic strains of Trypanosoma cruzi.

The kinetics of macrophage activation were compared among inbred strains of mice (C3H, BALB, B6 and B10.A) that are known to differ in their relative resistance to infections with the myotropic strains (Colombian and CL) of Trypanosoma cruzi. The parameters utilized to measure macrophage activation were rapid spreading on glass surfaces, hydrogen peroxide release and tumour necrosis factor/cachectin production. Macrophages obtained from C3H (susceptible), BALB (intermediate) and B6 or B10.A (resistant) mice infected with both strains of T. cruzi began to spread rapidly at the onset of parasitaemia. Surprisingly, the amount of hydrogen peroxide released by peritoneal cells obtained from the more susceptible mouse strain (C3H) was significantly higher than in the other mouse strains. Also, only in the serum of C3H mice was tumour necrosis factor/cachectin detected. These results suggest that resistance against infections with myotropic strains of T. cruzi does not correlate with enhanced macrophage activation. It is also shown that the acquired macrophage activation is largely dependent on T-lymphocytes bearing the phenotypic marker CD4 (helper/inducer), since all parameters of macrophage activation were significantly inhibited in athymic mice or in C3H mice treated in vivo with monoclonal antibody anti-CD4+ T-cells.

Animals↗
PubMed1989

Metacyclic neutralizing effect of monoclonal antibody 10D8 directed to the 35- and 50-kilodalton surface glycoconjugates of Trypanosoma cruzi.

It was shown in this work that the infectivity of metacyclic forms of Trypanosoma cruzi was affected upon interaction with the monoclonal antibody (10D8), which reacts with a carbohydrate epitope of the 35- and 50-kilodalton (kDa) surface glycoconjugates. The invasion of Vero cells by metacyclic forms of strains Tulahuen and G was inhibited 50 to 67% in the presence of 10D8 (10 micrograms/ml), whereas a nonrelated monoclonal antibody to Plasmodium berghei had no such effect. In mice that were inoculated with metacyclic forms preincubated with 10D8 or that had passively received 10D8 before challenge with metacyclic forms, a considerable decrease in the parasitemia levels was observed. The 35- and 50-kDa antigens were detectable by the galactose oxidase and sodium boro[3H]hydride procedure but not by surface iodination or metabolic labeling with [35S]methionine, suggesting that they may be of glycolipid nature. The finding that the 35- and 50-kDa antigens are major bands recognized by sera of mice immunized with killed metacyclic forms and protected against acute infection, in addition to the results with 10D8, indicate that these glycoconjugates may play an important role in the metacyclic form-host cell association that initiates T. cruzi infection.

Animals↗