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Biomedical subjects

P Orsolini

Publications and source records attributed to P Orsolini.

At least 37 records · Page 2Linked to original sources
PubMed1990

Effect of teicoplanin and vancomycin on Staphylococcus aureus ultrastructure.

Morphological changes induced by teicoplanin and vancomycin on Staphylococcus aureus have been comparatively evaluated. The most pronounced structural damages were found on the cell wall which was uniformly thickened on bacteria exposed to teicoplanin while it was of irregular thickness and often absent around the cells in those exposed to vancomycin. The inhibitory action of teicoplanin on proteoglycan polymerization but not on nucleic acid and protein synthesis indicates that the effect in the wall is due to the accumulation at this level of proteoglycan soluble precursors continuously produced by the cell. The different effects induced by vancomycin on cell wall morphology can also be related to the compatibility of this antibiotic in altering cytoplasmatic membrane function and ribonucleic acid synthesis.

Anti-Bacterial Agents↗
PubMed1990

Kinetics of p24 antigenemia, IgM, IgG antibodies to p24 and p41 and Ig virus isolation in rabbits experimentally infected with HIV-1.

In rabbits experimentally infected with 1.10(5) u.i./ml HIV, IgM antibodies were detected 10-15 days after infection, reaching peak value two weeks later and remaining stable for two weeks long. Then a the IgM serotiters progressively decreased and were negative at ten weeks. HIV p24 antigen was detected ten-fifteen days after infection, reaching peak value five-six weeks later. Antigenemia subsequently decreased and reached a second peak after nine weeks. In our experimental conditions, the antigenemia persisted throughout the observation period. The IgG antibody titer reached a maximum two weeks after infection; the time course showed a decrease after ten weeks, followed by progressively decreasing fluctuating course. After twenty four weeks of infection the serotiter values though lower were always positive. Three-four weeks after infection we detected IgG antibodies to the major core protein p24. Reactivity of IgG antibodies to gp41 was observed earlier than reactivity to p24; these antibodies were detected over six months after infection. Viruses indistinguishable from HIV were isolated from the peripheral blood mononuclear cells of infected rabbits 30, 60 and 180 days after infection. These data further confirm that the rabbit may serve as an economical and reproducible model for HIV infection in which vaccines and antiviral agents could be tested.

Animals↗
PubMed1989

[In vitro sensitivity of 3 strains of Leptospira interrogans to 3 different antibiotics].

Leptospirosis, anthropo-zoonosis ubiquitously widespread, is a social and economic problem still to be solved. The experimental and therapeutic employment of many antibiotics has largely been tested "in vitro" and "in vivo". In the following research we tried to evaluate, by experimental "in vitro" method, the sensitivity difference of three serovar strains of Leptospira interrogans to two macrolides, Erythromycin and Josamycin, compared with Penicillin. From standard cultures, previously treated with serial dilution of these antibiotics, the MIC and MSC, as quantitative parameters, have been stated. For the qualitative evaluation of the damages induced at ultrastructural level by the drug activity. Electron Microscopy investigations were performed on specimens from cultures treated for 6 hr with twice and tenfold the MSC. The present research confirms the good sterilizing efficaciousness "in vitro" of the tested macrolides (MSC less than 1 mcg/ml) and their different activity pathway.

Drug Resistance, Microbial↗
PubMed1989

Detection of IgG anti-HIV antibodies in mice experimentally infected with HIV-1.

In the present work we report our preliminary data demonstrating the susceptibility of mouse to HIV infection. IgG antibodies were found in mice intraperitoneally inoculated with H9/HTLV-IIIB infected cells. Infected mice showed a humoral response and the antibodies detection includes specific immunoglobulin directed against the major gene product of HIV. Two weeks after infection with HIV infected cells we detected in mice IgG antibodies to p24, and the reactivity to gp41 was observed as early as reactivity to p24 and persisted throughout observation period. The persistence of specific antibody response to HIV after one year seems to demonstrate the possibility of the use of the mouse as animal model for HIV in vivo experiments. Studies concerning the degree and kinetic of HIV infection in mouse are in progress in our laboratory.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Radioimmunoassay for octapeptide analogs of somatostatin: measurement of serum levels after administration of long-acting microcapsule formulations.

The development of a long-acting delivery system for D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2 (RC-160), an octapeptide analog of somatostatin, required the establishment of a method for determining the concentration of this analog in serum during treatment. A sensitive and specific radioimmunoassay (RIA) for RC-160 was developed and used for following the rate of liberation of this peptide from microcapsules of poly(DL-lactide-coglycolide). Antibodies were generated in a rabbit against RC-160 conjugated to bovine serum albumin with glutaraldehyde. At an antiserum dilution of 1:100,000, the antibodies bound approximately 25% of added radiolabeled RC-160. Somatostatin octapeptide analogs that had a disulfide bridge showed crossreactivity with the antiserum, but analogs without the disulfide bridge and other peptides tested did not crossreact. The minimum detectable dose of RC-160 was 10 pg. Intra- and interassay coefficients of variation ranged from 9.1% to 12.8% and from 14% to 30%, respectively. The RIA was suitable for direct determination of RC-160 in serum. Eleven prototype batches of microcapsules were tested in rats, and the rate of release of the analog from the microcapsules was followed. An improved batch of microcapsules made from RC-160 pamoate maintained high serum levels of RC-160 for more than 30 days after intramuscular injection. The RIA should be of value for monitoring levels of this analog in serum during long-term therapy.

Animals↗
PubMed1988

Identification of two subtypes of serotype 4 human rotavirus by using VP7-specific neutralizing monoclonal antibodies.

Two distinct subtypes of human rotavirus serotype 4 were identified by using neutralizing monoclonal antibodies directed to the major outer capsid glycoprotein, VP7, of strains ST3 (subtype 4A) and VA70 (subtype 4B). Specimens containing serotype 4 rotavirus, obtained from different countries, were examined for subtyping by using solid-phase immune electron microscopy, enzyme-linked immunosorbent assay, and, for cell culture-adapted strains, neutralization assay. All 59 human rotavirus strains identified as serotype 4 by using animal antisera were classified into either subtype by monoclonal antibodies. This suggests that the antigenic difference between the two subtypes is a consequence of critical variations within the immunodominant serotype 4-specific neutralization site of rotavirus VP7. Subtype 4A (ST3-like) strains were predominant and were detected in stools from patients with gastroenteritis, as well as from healthy infants and young children.

Animals↗
PubMed1988

The morphogenesis of BLV (bovine leukemia virus) cultivated on FLK (fetal lamb kidney): an ultrastructural study.

A new cell line, obtained by co-cultivation of fetal lamb kidney cells and lymphocytes collected from an adult calf affected by enzootic bovine leukemia, was studied for bovine leukemia virus (BLV) morphogenesis. In this new cell line, called FLK-BLV, persistently infected with BLV, we identified extracellular and intracellular BLV particles. We never observed "budding" particles along the cell surface, and therefore assumed it was a new BLV maturation process in the cell vacuoles. In fact we found mature and non-mature particles connected with the cell-membrane system or cellular debris within vacuoles. We suggest that the viral envelope could be supplied by vacuole membrane. In our samples we also observed a cytopathic effect with syncytia formations similar to those observed on other BLV-producing cell lines.

Animals↗
PubMed1987

Human immunodeficiency virus (HIV): an ultrastructural study.

H-9 cells producing HIV were examined by electron microscopy to value the virus-host cell relationships. HIV fine structure was also studied. HIV induces little cellular damages and it can penetrate into the cytoplasm by phagocytosis. Phagocytosis of the virus could play an important role in the mechanism of cellular infection.

Cell Line↗
PubMed1985

Life cycle of P. carinii in the lung of immuno-compromised hosts: an ultrastructural study.

We describe the ultrastructural features of interstitial pneumonia and life cycle of P. carinii in the lung of immuno-compromised hosts. The hyperplasia and edema of alveolar lining cells appear to be largely responsible for the extensive desquamative alveolitis which characterizes the histopathologic features of P. carinii in the lung of immuno-compromised hosts. The ultrastructural data concerning the ameboid trophozoite, particularly the presence of lobopodies and the reduplication by binary fission, associated with cyst forming capacity, suggest that P. carinii can be reasonably placed within the Protozoa.

Animals↗
PubMed1984

In vitro evaluation of ceftazidime (GR 20263), amikacin and sisomicin, in a model simulating serum pharmacokinetics of therapeutic doses.

The activity of ceftazidime, amikacin and sisomicin was investigated in an in vitro model using varying concentrations of antibiotic which mimic the serum levels of patients after the intramuscular administration of a 500, 250 and 70 mg dose respectively. Using this test, during the time of the agar MIC value correlation, ceftazidime, amikacin and sisomicin proved to be active against strains sensitive to 16 micrograms/ml, 8 micrograms/ml and 4 micrograms/ml respectively. Using the above concentrations as the cut-off points in defining the sensitivity of the strains, ceftazidime revealed the same level of activity as amikacin (6 and 5 resistant strains respectively out of the 185 tested) and proved much more active than sisomicin (48 resistant strains).

Amikacin↗
PubMed1982

Experimental infections for the evaluation of beta-lactamase resistance.

The antibacterial activity and pharmacokinetics of the beta-lactamase-stable cephalosporin cefuroxime and the gram-negative beta-lactamase-susceptible cephalosporin cefazolin were compared in two contrasting infection models in which Proteus morganii 82, which produces chromosomally mediated beta-lactamase, was the pathogen. In the rat paw model, characterized by high numbers of localized bacteria, cefazolin was destroyed at the site of infection and consequently did not produce a therapeutic response. In the mouse intraperitoneal model cefazolin was also inactive, despite peritoneal concentrations being unaffected by high counts of the beta-lactamase-producing P. morganii in the body cavity. In contrast the pharmacokinetics of cefuroxime was unaffected by the presence of the beta-lactamase-producing P. morganii, and good therapeutic responses were seen in both models.

Animals↗
PubMed1981

Synergistic interaction of bactericidal drugs and a factor present in serum ultrafiltrate.

Ultrafiltrate of serum of guinea-pig and man contains a factor which interacts synergistically with cephaloridine, kanamycin, and nalidixic acid against Escherichia coli. The factor on its own is not bactericidal. Gel filtration showed that the main peaks of the fractions with biological activity correspond to a MW of about 200. Chemical analysis excluded the presence of carbohydrates, proteins, ribonucleic acid at levels detectable with standard methods. Moreover the activity of the factor was not destroyed by meat nor by acid and enzymatic hydrolysis. A sequential mechanism or a reaction of the factor with drugs are considered as two possible explanations of the interaction.

Animals↗
PubMed1979

Effect of non-steroidal antiinflammatory drugs on some biological activities dependent on complement activation.

The paper presents the results of a study on the action of five non-steroidal antiinflammatory agents (phenylbutazone, indometacin, acetylsalicylic acid, niflumic and flufenamic acids) on two biological activities which are dependent on complement activation: opsonization of bacteria and membrane damage, the latter evaluated both with the classic immunohemolytic system and with a bactericidal assay. The three biological assays differ for complement sequences involved. Flufenamic and niflumic acids showed high inhibitory activity in the lytic assays. Human complement was more sensitive to inhibition than guinea-pig complement. Phagocytic test confirmed the inhibitory activity of flufenamic acid on complement dependent opsonization.

Animals↗