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Biomedical subjects

A Visconti

Publications and source records attributed to A Visconti.

At least 55 records · Page 3Linked to original sources
PubMed1994

Isolation and characterization of new chlamydosporol related metabolites of Fusarium chlamydosporum and Fusarium tricinctum.

Fusarium chlamydosporum strain T-826 isolated from corn in the USA produced chlamydosporol and two analogs which have been identified by various spectroscopic techniques as: 7,8-dihydro-5-hydroxy-4-methoxy-trans-7,8-dimethyl-2H,5H-pyrano(4, 3-b)pyran-2-one (or isochlamydosporol) and 4-methoxy-5-hydroxymethyl-6-(3-butan-2-ol)-2H-pyran-2-one (or chlamydospordiol). Chlamydosporol (compound a + b) chlamydospordiol (compound c) and isochlamydosporol (compound d) were produced together (up to 6000 micrograms/g) by 3 out of 11 isolates of F. chlamydosporum and by 3 out of 24 isolates of F. tricinctum from various substrates and geographic origin. Three isolates of F. chlamydosporum and one isolate of F. tricinctum produced only chlamydospordiol and 2 isolates of F. tricinctum produced chlamydosporol (a + b), and chlamydospordiol (c).

Chromatography, High Pressure Liquid↗
PubMed1994

Detection of peptaibols and their hydrolysis products in cultures of Trichoderma species.

Fifteen strains of Trichoderma belonging to 12 different species for potential use in biological control were examined for their ability to produce polypeptide antiobitics (peptaibols). Gas chromatography was used to detect the hydrolysis products of peptaibols after esterification with n-propanol and derivatisation with heptafluorobutyric anhydride. In particular, amino acids (alpha-aminoisobutyric acid, and isovalin) and amino alcohols (phenylalaninol, leucinol, and valinol) were used as markers for the detection of different peptaibols. alpha-Aminoisobutyric acid, an amino acid characterising all peptaibols, was detected in all cultures examined, indicating that the production of peptaibols is a common feature of the various Trichoderma species. Different amino acid/amino alcohol combinations suggested specific peptaibol production. On this basis, the peptaibol paracelsin was confirmed by HPTLC in 11 out of 15 Trichoderma strains cultures. Valinol was not found in any culture extract, indicating the lack of trichotoxins production. Culture extracts of the 6 tested Trichoderma strains were extremely toxic to Artemia salina larvae; for 5 of them this toxicity could be attributed to paracelsin (calculated LD50 = 2.2 microM).

Alamethicin↗
PubMed1994

Ochratoxin A in human serum samples collected in southern Italy from healthy individuals and individuals suffering from different kidney disorders.

Ochratoxin A was determined in human serum samples, collected in the south of Italy in November 1992, using ion-pair liquid chromatography and fluorescence detection. The samples were collected from healthy people (65 subjects) as well as from people with different kidney disorders. Five different kinds of kidney disorders were represented: transplanted subjects (13), chronic glomerulonephritis (8), renal calculus or cyst (6), chronic renal failure (13), and subjects treated by dialysis (28). The mean and median concentrations of ochratoxin A in the healthy group was 0.53 and 0.44 ng/ml serum, respectively. The highest mean concentration was found in the group of patients treated by dialysis, 1.4 ng/ml serum. A higher incidence of samples containing > 0.44 ng ochratoxin A/ml serum was found in the dialysis group, compared to the other groups. Comparing the mean concentrations by Student's t-test, a significant difference was found between the mean concentrations of the healthy group and of the group of patients treated by dialysis (P < 0.01). No other significant differences were found when comparing the groups two at a time.

Analysis of Variance↗
PubMed1993

HTLV-II/HIV-1 coinfection and risk for progression to AIDS among intravenous drug users.

To determine whether coinfection with HTLV-II influences the course of HIV-1 infection, we evaluated the progression from asymptomatic HIV infection (CDC group II) to persistent generalized lymphadenopathy (CDC group III) to AIDS-related complex (CDC group IVA) to full-blown AIDS (CDC group IVC) to death from AIDS in two groups of HIV-seropositive intravenous drug users (IVDUs). The first group consisted of 123 patients infected with HIV-1 only, and the second comprised 22 patients with serological and molecular evidence of HTLV-II/HIV-1 coinfection. Results of the immunological and clinical follow-up indicated a greater likelihood of developing persistent generalized lymphadenopathy among individuals infected with HIV-1 alone than among those coinfected with HTLV-II. However, no statistical difference was detected between the two groups in the depletion of CD4+ cells, the temporal decrease of the CD4/CD8 ratio, or the progression to ARC or AIDS or to death from AIDS. These findings suggest that HTLV-II may have no effect on the clinical evolution of HIV infection in IVDUs, which may be explained by the lack of pathogenicity of the HTLV-II coinfecting strain(s) and/or other still unclear biological or immunological cofactors or mechanisms.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Immunomodulatory effects of fusarochromanones TDP-1 and TDP-2.

An in vitro peripheral lymphocyte blastogenesis system was used to investigate the biological activities of the fungal toxin fusarochromanone (TDP-1) and its monoacetyl derivative TDP-2. Briefly, cultures of human or bovine peripheral lymphocytes were exposed to TDP-1 or TDP-2 and a mitogen (PHA, Con A or PWM). After a standard incubation time, cell proliferation was quantified using the MTT bioassay. Human and bovine lymphocyte proliferation was inhibited by high concentrations of TDP-1; however, bovine lymphocyte proliferation was significantly increased at low concentrations of TDP-1. TDP-2 has similar but less pronounced effects on lymphocyte proliferation.

Amino Acids↗
PubMed1992

Toxicity of some Fusarium section Sporotrichiella strains in relation to mycotoxin production.

The relationship between the toxicities of crude extracts and purified toxins of Fusarium spp. belonging to the section Sporotrichiella has been assessed. Toxicity was determined on the basis of death of Artemia salina larvae and of viability and blastogenic response of bovine and human lymphocytes. Trichothecene-producing strains of Fusarium sporotrichioides and Fusarium poae were toxic to A. salina and to lymphocyte blastogenesis. A strain of Fusarium tricinctum, producing visoltricin and chlamydosporol, induced differentiated activity in different bioassays (toxicity to A. salina but only minor activity against lymphocyte blastogenesis). Other, non-toxin-producing strains of Fusarium chlamydosporum, F. poae, and F. tricinctum were not active in the tested biosystems.

Animals↗
PubMed1991

Selective determination of altertoxins by high-performance liquid chromatography with electrochemical detection with dual "in-series" electrodes.

A selective method for the determination of altertoxin-I and altertoxin-II by high-performance liquid chromatography with electrochemical detection is described. Altertoxins were separated on a reversed-phase column with methanol-water containing 0.1 M sodium nitrate and 1 mM nitric acid (60:40) as eluent and detected with dual in-series electrodes operating in the "redox" mode (generator electrode +1.0 V, indicator electrode -0.1 V). The method was applied successfully to the determination of sub-ppm levels of altertoxins in samples of maize, rice and tomatoes infected by Alternaria alternata.

Benz(a)Anthracenes↗
PubMed1991

Cytotoxic and immunotoxic effects of Fusarium mycotoxins using a rapid colorimetric bioassay.

A colorimetric MTT (tetrazolium salt) cleavage test was used to evaluate cytotoxicity of twenty-three Fusarium mycotoxins on two cultured human cell lines (K-562 and MIN-GL1) as well as their inhibitory effect on proliferation of phytohemagglutinin-stimulated human peripheral blood lymphocytes. The values of 50% inhibition of lymphocyte blastogenesis were very close to the 50% cytotoxic doses observed with the more sensitive cell line (MIN-GL1). T-2 toxin was the most cytotoxic with CD50 and ID50 values less than 1 ng/ml. Type A trichothecenes were the most cytotoxic followed by the type B trichothecenes; the non-trichothecenes were the least cytotoxic. The MTT cleavage test, in conjunction with cell culture, is a simple and rapid bioassay to evaluate cytotoxicity and immunotoxicity of Fusarium mycotoxins.

Cell Line, Transformed↗
PubMed1989

Profiling of Alternaria mycotoxins in foodstuffs by high-performance liquid chromatography with diode-array ultraviolet detection.

The potential of high-performance liquid chromatography (HPLC) with diode-array detection for the profiling of mycotoxins in food samples has been demonstrated. A gradient elution reversed-phase chromatographic method coupled with a suitable extraction procedure was devised for the separation and detection of major Alternaria mycotoxins in foodstuffs. Altenuene, alternariol, alternariol methyl ether (dibenzo-alpha-pyrone derivatives), altertoxin-I and altertoxin-II (perylene derivatives) were profiled in extracts of artificially infected maize, rice and tomato samples and naturally contaminated sunflower seeds. First evidence of the occurrence of a new dibenzo-alpha-pyrone derivative in Alternaria cultures is also reported.

Alternaria↗
PubMed1989

Fusarium species and their mycotoxins in infected corn in Italy.

Surveys of corn (infected plants and commercial kernels) for Fusarium species and their mycotoxins were carried out on samples collected all over Italy and from some European and mediterranean countries. Investigations on samples of corn stalk and ear rot standing in the field, mainly collected in southern Italy, proved to be contaminated with zearalenone (ZON), zearalenols (ZOL), and deoxynivalenol (DON). The Fusarium species most frequently isolated, and their recorded toxigenic capability (in parentheses), were: F. moniliforme; F. culmorum (ZON, ZOL, DON, 3AcDON); F. equiseti (ZON, ZOL); and F. proliferatum (MF). Along with these species, F. graminearum group 2 (ZON, DON and/or 3AcDON or 15AcDON); F. chlamydosporum; F. acuminatum (type-A trichothecene derivatives); and F. semitectum were often found to be associated. F. heterosporum (ZON, ZOL); F. solani; F. crookwellense (ZON, ZOL, FUS, NIV); F. oxysporum (MF); F. avenaceum (MF); F. sporotrichioides (T-2 toxin and derivatives); and F. poae (DAS, MAS) were occasionally isolated.

Fusarium↗
PubMed1989

Relationship of nocturnal bronchoconstriction to sleep stages.

The possible role of sleep stages in the pathogenesis of nocturnal asthmatic attacks is still under debate because previous studies suffered methodologic limitations that prevented the possibility of providing a clear-cut answer to the question. To evaluate the relationship of nocturnal asthma to sleep, eight asthmatics with unstable asthma (seven with history of nocturnal wheeze) and four reference subjects were submitted to all-night polysomnography, including the continuous evaluation of esophageal and supraglottic pressure (with two catheters) as well as of airflow (with a face mask), so as to derive total lung resistance, supraglottic resistance, and, by subtraction lower respiratory resistance (Rlr). Stage 3-4 was characterized by the highest peaks in Rlr and by longer episodes of bronchoconstriction; conversely, neither the onset nor the remission of the latter were specifically related to any sleep stage. Considering episodes remitted with an awakening. Stage 3-4 was marked by higher Rlr peaks than during REM sleep. We conclude that sleep plays a contributory role in the multifactorial pathogenesis of nocturnal asthma, with a higher susceptibility during slow-wave sleep, probably related to a decreased responsivity to resistive loads.

Adult↗
PubMed1989

Peak flow records in asthma: evaluation of an algorithm for interpretation of patterns.

The clinical value of serial measurements of peak expiratory flow (PEF) in asthma is well established, but the analysis of the PEF records is not standardized. We developed an algorithm for interpretation of PEF, based upon the characteristic features of chronic airflow limitation, and retrospectively analysed the PEF of fifty outpatients affected by non-seasonal asthma. For each patient we correlated the developed indices of evolution of PEF with, respectively, the severity of asthma (evaluated in terms of consumption of drugs), forced expiratory volume in one second and with the trend of the indices over several months. The developed indices were well correlated with the severity score and to a lesser extent to other investigated parameters. These results seem to provide a useful approach to a computerized evaluation of the results of PEF monitoring.

Adolescent↗
PubMed1988

Comparison of the effect of oxitropium bromide and of slow-release theophylline on nocturnal asthma.

The effects of a new inhaled antimuscarinic drug, oxitropium bromide, and of a slow-release theophylline preparation upon nocturnal asthma were compared in a placebo-controlled double-blind study. Two samples were studied: 12 patients received oxitropium at 600 micrograms (6 subjects) or at 400 micrograms t.i.d. (6 subjects) whereas 11 received theophylline at 300 mg b.i.d. Morning dipping, assessed by the fall in peak flow overnight, was significantly reduced in the periods when either active drug was taken, whereas no difference was noticed during the placebo administration. No significant difference was noticed between results obtained with either active drug, as well as with either dosage of oxitropium. No subject reported side effects of oxitropium, as compared to three subjects reporting nausea, vomiting and tremors after theophylline. Oxitropium proves to be a valuable alternative to theophylline in nocturnal asthma, since it is equally potent, safer and does not require the titration of dosage.

Adolescent↗
PubMed1988

Validation of morning dip of peak expiratory flow as an indicator of the severity of nocturnal asthma.

Overnight falls in peak expiratory flow (PEF) (with the morning dip of the index) may be considered the hallmark of nocturnal asthma. To validate the morning dip a quantitative marker of the degree of nocturnal bronchoconstriction, the dip was measured in 11 subjects (six with a history consistent with nocturnal asthma) undergoing all-night monitoring of lower respiratory resistance by a double-catheter method. In six subjects, marked and recurrent increases in resistance were recorded, along with morning dips higher than 20 percent; however, on the following morning, only two of them reported having suffered significant breathlessness and wheeze. Peak and average values for resistance, as well as the duration for which resistance was increased, were closely correlated with the magnitude of morning dips. Therefore, unlike the subjective report, PEF may be considered a reliable quantitative indicator of nocturnal bronchoconstriction.

Adult↗
PubMed1987

Metabolism of zearalenone by sow intestinal mucosa in vitro.

Homogenized intestinal mucosa samples from sows were incubated with zearalenone in the presence of NADPH or UDPGA. In addition, UDPglucuronosyltransferase activity in the microsomal fraction of mucosa was determined using 1-naphthol as substrate. In the presence of NADPH, zearalenone was reduced to both alpha- and beta-zearalenol (0.37 +/- 0.18 and 0.29 +/- 0.11 nmol/mg protein/hr in the duodenum and jejunum, respectively). The beta-isomer was the predominant metabolite. Glucuronide conjugation of zearalenone was very high compared with the level of reduction occurring (11.3 +/- 6.1 and 9.4 +/- 5.8 nmol conjugated/mg protein/hr in the duodenum and jejunum, respectively). There was no correlation between the rates of glucuronide conjugation of zearalenone and 1-naphthol, indicating that they depend upon two different isoenzymes of UDPglucuronosyltransferase.

Animals↗
PubMed1986

Antibiotic Y: biosynthesis by Fusarium avenaceum (Corda ex Fries) Sacc., isolation, and some physicochemical and biological properties.

A compound very similar to the mycotoxin citrinin was observed on thin-layer chromatographic plates during the screening analysis of grain extracts. This compound was produced by 22 of the tested Fusarium avenaceum (Corda ex Fries) Sacc. strains isolated from wheat, triticale, barley, corn, and potatoes. A chemical test confirmed the presence of an unknown compound, which was given the preliminary name of antibiotic Y (indicating yellow fluorescence). The following properties of the new metabolite are described: spectroscopic (UV, infrared, proton nuclear magnetic resonance, fluorescence, and mass spectrometry), phytotoxic, antibiotic (inhibitory effect of bacterial growth), and toxic (toxicity to Artemia salina, chicken embryos, and mouse fibroblasts). Elemental analysis of the compound showed that it had the general formula C15H10O8, in agreement with the mass spectrometric finding that the molecular ion had a molecular weight of 318. The structure of the compound is presently under study.

Animals↗