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Biomedical subjects

G Morace

Publications and source records attributed to G Morace.

At least 37 records · Page 2Linked to original sources
PubMed1998

Polypeptide 3AB of hepatitis A virus is a transmembrane protein.

Hepatitis A virus (HAV) protein 3AB is a membrane-interacting protein containing a stretch of 21 hydrophobic amino acid residues. The nature of its membrane association was studied in detail by analysing various deletion mutants. In vivo and in vitro expression of the wild-type protein and its mutants allowed to demonstrate that the hydrophobic domain interacts with membranes and to define the portions essential for this feature. Furthermore, the results suggest that 3AB behaves as an integral membrane protein. Expression in Escherichia coli showed that 3AB can be isolated, in association with membranes, both in monomeric and in dimeric form. This finding was confirmed in vitro after post-translational incubation of the protein with microsomal membranes. Analysis of deletion mutants demonstrated that the dimerization region colocalises with the hydrophobic transmembrane domain, implicating that HAV 3AB could form oligomers mediated by the interaction of transmembrane alpha-helices.

Amino Acid Sequence↗
PubMed1998

[A new computerized electrocardiographic method of the study of the QRS complex in the diagnosis of myocardial ischemia (preliminary results)].

Based on the premise that the QRS complex is also involved in reversible ischemia, we designed a computerized electrocardiographic method, that we have named Ventricular Ischemic Site Analysis (VISA). This method compares mean resting QRS to the QRS complex recorded during exercise or pharmacologic stress. The effect of ischemia on the electrical process of myocardial depolarization can be seen as a smaller slope in the QR and/or RS segment of the QRS signal, thus causing a local change in shape of the QRS. This method makes it possible to evaluate both the maximum entity of the change in shape and the time at which this occurs with reference to the beginning of the cycle. The VISA test was compared to SPECT and to the normal ECG stress test on a group of 53 patients who underwent a SPECT 99mTc-Sestamibi for suspected myocardial ischemia. Among the 39 patients confirmed as ischemic, the VISA test was positive in 37, while the ischemic alterations of the ST-T segment were observed in only 10 patients. According to this study, the sensitivity of the VISA test is comparable to the levels seen in SPECT. Moreover, this method demonstrates a trend towards localization of the ischemia in posterior or lateral sites when the shape change in localized in RS segment, and in anterior or infero-apical sites when the change is in QR segment. In addition to increasing sensitivity with respect to normal ECG stress tests, this method may also represent a new field of application for the ECG stress test, offering the possibility of localizing ischemic areas via simple computerized electrocardiography.

Adult↗
PubMed1997

Site-directed mutagenesis of hepatitis A virus protein 3A: effects on membrane interaction.

Due to a stretch of hydrophobic amino acids, protein 3A of hepatitis A virus (HAV) has been suggested to act as a membrane anchor or a carrier of the genome-linked protein 3B (VPg) during viral RNA synthesis. Mutagenesis analysis was performed in order to elucidate the role of the N- and C-terminal tracts of protein 3A in cell membrane interaction. Expression of the mutated proteins in E. coli cells demonstrated that the presence of positively charged residues at the C-terminus is not required for membrane anchoring. Changes in the primary sequence involving charged amino acids at the N- and C-termini critically influenced the ability of the protein 3A of a cytopathic strain of HAV to change bacterial membrane permeability. This result demonstrates the strict correlation between the structure and pore-forming potential of HAV protein 3A.

Amino Acid Sequence↗
PubMed1997

Comparative analysis of prognostic indicators of aspergillosis in haematological malignancies and HIV infection.

The objective of this study was to identify the prognostic factors influencing the outcome of aspergillosis in two models of immunodeficiency, namely haematological malignancies and HIV infection. The study is based on a 5 year prospective logistic regression analysis of risk factors, clinical features, radiological findings and therapy affecting the prognosis of aspergillosis in 43 patients, i.e. 27 haematological neoplastic patients (group A) and 16 HIV infected patients (group B). Univariate analysis indicated that neutropenia (P = 0.02), haemoptysis (P = 0.03) and concomitant AIDS (P = 0.02), negatively influenced the prognosis of aspergillosis. Comparing the two groups of patients, significant differences emerged in the prognostic indicators. In particular respiratory failure (P = 0.02) and radiological bilateral involvement of the lungs were associated with a poor prognosis in group A (P = 0.04) and low (2100/mm3) T CD4+ cell count in group B (P = 0.02). At variance, a better prognosis was documented in patients treated with sequential therapy (amphotericin B and itraconazole) only within the group of haematological patients (P = 0.003). On multivariate analysis sequential therapy (P = 0.01) and AIDS (P = 0.03) were independent prognostic indicators of aspergillosis. In conclusion, our prospective study indicates that aspergillosis, although an uncommon event in patients with HIV infection, has a more severe prognosis in comparison to haematological patients. Future prospective clinical trials are necessary to confirm the real importance of the sequential therapy, with amphotericin B and itraconazole, in patients with aspergillosis.

Adult↗
PubMed1997

Interaction of hepatitis A virus (HAV) precursor proteins 3AB and 3ABC with the 5' and 3' termini of the HAV RNA.

RNA secondary structures within the terminal nontranslated regions of entero- and rhinoviral genomes interact specifically with viral nonstructural proteins and are required in cis for viral RNA replication. Here we show that recombinant hepatitis A virus (HAV) polypeptide 3ABC specifically interacts in vitro with secondary RNA structures formed at both the 5' and 3' terminus of the viral genome. Similar to protein 3AB, HAV 3ABC bound to the 3' terminal RNA structure which did not interact with the mature proteinase 3C. In contrast to 3AB, 3ABC interacted with RNA stem-loop IIa and combinations of individual secondary structure elements of the 5' noncoding region. RNA binding of the precursor polypeptide 3ABC was 50 times stronger than that of 3AB and 3C, implicating a specific role of this stable processing intermediate in viral genome replication.

3C Viral Proteases↗
PubMed1997

Fluconazole resistant oral candidiasis in HIV-infected patients.

OBJECTIVE: To evaluate the risk factors associated with the emergence of fluconazole resistant Candida spp. in HIV-infected patients with oral candidiasis. METHODS: Candida spp. were isolated from oral swabs and tested in vitro for resistance to fluconazole. The factors potentially correlated with vazole-resistent Candida spp. infections were investigated. RESULTS: Fifty-one out of 118 patients (43%) with oral candidiasis had fluconazole resistant Candida spp. The following factors were significantly associated with the development of fluconazole resistance: (1) more than five episodes of oral candidiasis in the previous year (P < 0.001); (2) fluconazole therapy in the previous 6 months (P < 0.001); (3) C3 category of HIV infection (P < 0.001); and (4) low number of TCD4+ cells (< 50 mm3, P = 0.002). According to multivariate analysis, previous therapy with fluconazole was the only risk factor that independently influenced the development of Candida spp. resistance (P = 0.003). CONCLUSIONS: The prophylaxis and therapy of mild fungal infections in HIV-infected patients, which may lead to azole resistance, should be carefully considered.

AIDS-Related Opportunistic Infections↗
PubMed1997

Identification of various medically important Candida species in clinical specimens by PCR-restriction enzyme analysis.

A single primer pair amplifying a cytochrome P-450 lanosterol-14 alpha-demethylase (L1A1) gene fragment that encodes a highly conserved region was used to detect yeast DNA in clinical specimens. Positive PCR products were obtained from genomic DNAs of Candida albicans, C. parapsilosis, C. tropicalis, C. guilliermondii, C. krusei, C. (Torulopsis) glabrata, and C. kefyr. No human, bacterial, or parasitic DNA was amplified. The sensitivity was evaluated for C. albicans genomic DNA by using various DNA concentrations (200 pg to 2 fg). The amplified DNAs of Candida species with unknown P-450 L1A1 gene sequences were subcloned and sequenced. Identification at the species level was achieved by digestion of the PCR products with different restriction enzymes. A specific restriction enzyme analysis pattern was determined for each species investigated. Subsequently, we used PCR to detect specific yeast DNA directly with clinical specimens such as blood and bronchoalveolar lavage specimens. After appropriate treatment, the specimens were processed by PCR and the results were compared with those obtained by traditional diagnostic procedures such as cultures and serology. Although preliminary, the PCR results seem to correlate well, at least for blood, with those of antigen detection assays and traditional blood cultures, with a better and earlier detection of candidemia.

AIDS-Related Opportunistic Infections↗
PubMed1997

The role of bronchoalveolar lavage in the microbiological diagnosis of pneumonia in patients with haematological malignancies.

In the aetiological diagnosis of pulmonary infections in patients affected by haematological malignancies we evaluated the utility of bronchoalveolar lavage (BAL). One hundred and twenty-seven BAL were performed in 119 patients. In our series, we identified the agent of pneumonia in 53.5% of episodes with the best results in aspergillosis, very common in these patients. The previous empirical anti-infective treatment was modified in 14 episodes (11%). The procedure was generally well tolerated and only one patient bled. We maintain that BAL is a useful diagnostic tool for detecting the agents of pulmonary infections in patients with haematological malignancies, especially when the routine microbiological procedures fail, and it also represents a good alternative to more invasive procedures.

Adolescent↗
PubMed1997

[Mycotic vulvovaginitis].

Vulvovaginitis is the most common clinical manifestation of fungal infections causing human mycoses; the incidence occurs in 10% of women, during pregnancy the incidence achieves 30% of cases. Candida albicans has resulted to be the most commonly isolated agent in patients with fungemia. In fact, Candida appears to be the species recovered in as many as 90% of cases. They are mainly the sexual activity, hormonal contraception and several pathologies such as diabetes mellitus and thyroiditis responsible for the pathogenesis of infection. The first symptom of this infection is usually pruritus associated to leukorrhea, dyspareunia and vulvovaginal irritation. Antifungal therapy may be required in more severe cases of vulvovaginal candidiasis. Candida species can be identified on isolation culture media including agar and on direct examination. Diagnosis can also be made through san immunologic examination. However, the authors confirm that the risk factors together with a correct diagnosis of the Candida etiological agent in the different species (albicans, glabrata, tropicalis, krusei) should be accurately investigated in order to give the correct therapeutical approach.

Antifungal Agents↗
PubMed1996

Analysis of the risk factors associated with the emergence of azole resistant oral candidosis in the course of HIV infection.

The objective of this case-control study, conducted in a large Italian university hospital over a 12-month period, was to evaluate the risk factors associated with the emergence of azole resistant oral candidosis in 64 Human Immunodeficiency Virus (HIV) infected patients. A swab was obtained from each patient by brushing candidal lesions. Candida albicans was isolated in 41 patients (64%), Candida glabrata in ten (16%), Candida krusei in five (8%), Candida kefyr in two (3%), Candida tropicalis in two (3%), and Candida lipolytica and Candida guilliermondii in one case, respectively. Two patients suffered a double infection i.e. C. albicans+C. krusei and C. albicans+C. glabrata, respectively. Candida species were tested in vitro for their susceptibility to ketoconazole, fluconazole, itraconazole and amphotericin B. MICs of the four antifungal drugs were obtained for each yeast using a microdilution broth method developed in our laboratory. Twenty four (37%) of the isolated strains were resistant both to itraconazole and fluconazole, five (8%) to fluconazole alone, and two (3%) to ketoconazole alone, while none of the isolated strains was resistant to amphotericin B. Patients with oral candidosis caused by a strain resistant to one or more azole drug were compared to control patients with azole-susceptible oral candidosis. On univariate analysis, more than five episodes of oral candidosis in the last year (P = 0.01), previous use of azole therapy (P = 0.001), C2-3 category of HIV infection (P = 0.01) and low number of circulating CD4+ T-cells (P = 0.03) were significantly associated with an increased risk for the development of azole resistance. However, previous use of azole therapy was the only factor selected by a stepwise logistic regression analysis which was independently associated with the isolation of azole resistant strains (P = 0.003). Our findings indicate that, in view of the potential risk for the emergence and selection of azole resistant strains of Candida in patients with AIDS, it is important to carefully choose the antifungal drug for the therapy of mild fungal infections after evaluation of the in-vitro susceptibility of the isolated strains.

AIDS-Related Opportunistic Infections↗
PubMed1995

Recombinant expression of hepatitis A virus protein 3A: interaction with membranes.

The function of hepatitis A virus (HAV) protein 3A and its structural requirements were studied in vitro and in a bacterial expression system by comparing the polypeptide precursor 3AB derived from a cytopathogenic strain with that of an attenuated strain. Although the precursor polypeptides 3AB of both HAV strains bind to microsomal membranes after translation in vitro they differ in inducing membrane permeability when expression is induced in bacteria. Intake and release of macromolecules was dramatically increased when 3AB of the cytopathogenic strain was expressed. Amino acid sequence alignments suggest that membrane binding might be due to a hydrophobic stretch near the C-terminus of 3A found in all picornaviruses whereas the ability to induce permeability of E. coli membranes is determined by an amphipathic helix formed at the N-terminus of 3A of HAVFG.

Amino Acid Sequence↗
PubMed1995

Hansenula anomala killer toxin induces secretion and severe acute injury in the rat intestine.

BACKGROUND & AIMS: The yeast Hansenula anomala has been associated with gastrointestinal symptomatology and damage to the intestinal wall in humans. In vitro and in vivo, H. anomala secretes a toxin, killer toxin, which is lethal to other microorganisms. In view of the very high rate of killer phenotype expression recorded for H. anomala strains in nature, this study aimed to investigate the hypothesis that H. anomala killer toxin plays a role in the pathogenesis of H. anomala-induced enteritis. METHODS: Effects of active and heat-inactivated H. anomala killer toxin on intestinal fluid homeostasis and electrolyte balance were investigated in rat small intestine using a standard intestinal perfusion technique. Sections of the perfused jejunum tracts were examined histologically. RESULTS: H. anomala killer toxin induced a significant secretion of water and electrolytes. No significant change was observed when either heat-inactivated H. anomala killer toxin or control growth medium were tested. Histological analysis showed ischemic degeneration of villi and sloughing of surface epithelium in 50% of active H. anomala killer toxin-perfused jejuna. CONCLUSIONS: This paper presents original observations compatible with the hypothesis that H. anomala killer toxin plays a role in the pathogenesis of H. anomala-induced enteritis.

Animals↗
PubMed1995

Complete nucleotide sequence of a cytopathic hepatitis A virus strain isolated in Italy.

The molecular basis of the cytopathic effect induced in cell culture by some hepatitis A virus (HAV) strains and variants has not been determined. In order to assess the molecular mechanism(s) underlying this particular phenotype the genome of an Italian cytopathic isolate (strain FG) was sequenced from cDNAs obtained by RT-PCR. Sequence analysis revealed the presence of mutations common to either adapted or cytopathic variants of HAV. In particular, amino acid deletions in proteins VP1 and 3A were detected. Expression of protein 3A in E. coli showed that the N-terminal deletion renders this protein toxic to bacteria.

Amino Acid Sequence↗
PubMed1995

Fluconazole for primary prophylaxis of AIDS-associated cryptococcosis: a case-control study.

In order to verify whether fluconazole has a prophylactive effect against the occurrence of cryptococcosis in HIV-infected patients and to identify other factors capable of increasing or reducing the risk of this infection, we arranged a case-control study of 17 patients with cryptococcal infection. 34 controls were selected, matched by presence of an AIDS-defining event, CD4 cell count, and date of T-cell phenotyping. No significant difference in exposure to fluconazole, in total days of treatment, or in total dose administered was observed between cases and controls. However, control patients took a significantly higher average daily dosage of fluconazole and a linear tendency in risk reduction (p = 0.04) in relation to increasing dosage was observed. Antiretroviral therapy and an average daily fluconazole dose exceeding 150 mg both each reduced the risk of a cryptococcal infection.

AIDS-Related Opportunistic Infections↗
PubMed1994

Idiotypic intravaginal vaccination to protect against candidal vaginitis by secretory, yeast killer toxin-like anti-idiotypic antibodies.

The principles of idiotypic (Id) vaccination were used to immunize against vaginitis caused by Candida albicans, a widespread and sometimes intractable disease in women. To this aim, a murine mAb (KT4, IgG1) neutralizing in vitro the anti-Candida activity of a yeast killer toxin (YKT) was used as an Id vaccine to elicit Abs with toxin-like activity in a rat vaginitis model. Nonimmunized and isotype-matched, irrelevant mAb-immunized rats served as controls. An effective protection was obtained in Id-vaccinated animals, as demonstrated by a highly significant decrease in vaginal Candida CFU compared with controls. The protection was associated with rising vaginal titers of anti-idiotypic Abs (IdAb), prevalently of the IgA isotype, that were able to passively transfer the protective state to nonimmunized animals. The vaginal IdAb possessed YKT-like activity because they were able to kill in vitro the challenging fungal cells, and this killing was neutralized by the mAb KT4. Overall, these data demonstrate that secretory IdAb elicited by intravaginal Id vaccination with mAb KT4 protected the rats from the infectious challenge with Candida albicans by molecular mimicking YKT activity as its internal image.

Animals↗