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Biomedical subjects

A Focà

Publications and source records attributed to A Focà.

At least 37 records · Page 2Linked to original sources
PubMed1991

Aminoglycosides modify the in vitro metachromatic reaction and murine generalized Shwartzman phenomenon induced by Salmonella minnesota R595 lipopolysaccharide.

Endotoxin-neutralizing activity may be an important property for antibiotics to be used in severe sepsis. Several antibiotics, belonging to different classes, were evaluated as to their endotoxin-neutralizing ability, using the inhibition of an in vitro metachromatic assay for lipopolysaccharides and a murine generalized Shwartzman reaction model. Gentamicin, amikacin, and sisomicin have been found to share significant in vitro antiendotoxin activity at an antibiotic/endotoxin ratio as low as 1.0/5 (by weight) and to reduce the murine generalized Shwartzman reaction at an antibiotic/endotoxin ratio of 3.3/5.

Aminoglycosides↗
PubMed1991

Cefixime does not affect polymorphonuclear cell and monocyte functions from chronic lymphoid leukemia patients and from healthy donors.

It is well documented that to evaluate the efficacy of an antibiotic treatment it is important to know the relationships between the drug and the cells belonging to the immune system, by studying the possible effects on some cellular functions, particularly in immunosuppressed and immunodeficient patients. We describe the influence of cefixime, a new orally administered cephalosporin, on some polymorphonuclear cell (PMN) and monocyte functions from healthy donors and from patients affected by chronic lymphoid leukemia (CLL).

Administration, Oral↗
PubMed1991

Cefixime shows good effects on group A and group B beta-haemolytic streptococci.

There is continued interest in the development of oral beta-lactam compounds, which can be used clinically to treat various bacterial infections, particularly those caused by beta-haemolytic streptococci. Cefixime is a new orally active cephalosporin, with a broad spectrum of antibacterial activity, including Enterobacteriaceae, Haemophilus influenzae, Branhamella catarrhalis, Streptococcus pneumoniae and Streptococcus pyogenes. Cefixime is highly resistant to hydrolysis by most beta-lactamases. In this study the authors examined the effects of this molecule on Group A and Group B beta-haemolytic streptococci, recently isolated from clinical specimens in the authors' laboratory. MICs and the growth curves of 36 strains of Group A streptococci and the effects of sub-MICs on buccal cell adhesion were evaluated. The results show that concerning the sub-MIC cefixime effect on streptococci adherence, the treatment led to a decrease in adherence to the cells of the strains studied. Moreover cefixime showed good activity with 86.1% of the strains with MIC less than or equal to 0.5 microgram/ml, and the growth curves demonstrated that the molecule possesses a bactericidal effect after 3 h. Concerning Group B streptococci, 70.3% of the strains showed a MIC less than or equal to 2 micrograms/ml. In conclusion cefixime demonstrates good activity on beta-haemolytic streptococci, particularly those of Group A.

Anti-Infective Agents, Urinary↗
PubMed1991

Biological effects of Veillonella parvula and Bacteroides intermedius lipopolysaccharides.

A comparative study on the endotoxic effects of lipopolysaccharide (LPS) from Veillonella parvula ATCC 10790 and from Bacteroides intermedius BMH was performed using an in vivo approach in the C57BL/6 mouse. Phenol-water extracted LPS of such anaerobes was purified by ultracentrifugation and DNase/RNase digestion, and characterized by a metachromatic assay for endotoxins and by electrophoresis on SDS-polyacrylamide gel and silver staining. Mouse LD50 for V. parvula LPS was 1.479 mg and for B. intermedius greater than 3.160 mg. Sublethal amounts of the LPS from anaerobes as well as from facultative aerobes decreased daily water intake and body weight in the mouse. Endotoxin from Salmonella typhimurium SL1102, Escherichia coli 0128:B12 and V. parvula had a strong effect on water intake and body weight, whereas Bacteroides intermedius LPS activity was very weak. The results of the present report suggest that V. parvula LPS has a toxic in vivo activity on mouse, which is comparable to LPS from classic enteric organisms and stronger than B. intermedius LPS.

Animals↗
PubMed1990

In vitro activity of cefixime: correlation index between MIC and disc diffusion test.

In this study the in vitro antibacterial effects of cefixime are presented. Its activity was studied by evaluation of MICs, MBCs and the disc diffusion susceptibility method on Enterobacteriaceae, Staphylococcus aureus and Streptococcus pneumoniae. Moreover, the coefficient of correlation between MIC values and the disc diffusion susceptibility test was evaluated. The results support the wide antimicrobial activity of cefixime, which appears to be particularly effective against enterobacteria.

Anti-Infective Agents, Urinary↗
PubMed1988

Effect of bacterial endotoxin on lipoxygenase and cyclo-oxygenase metabolites by rat neutrophils and correlation with cellular functional parameters.

The effect of Salmonella enteritidis endotoxin on in vitro rat neutrophil cyclo-oxygenase and lipoxygenase metabolism, phagocytic activity, superoxide (O2-) generation, and microbicidal activity was investigated. Incubation of polymorphonuclear leukocytes (PMN) with 5, 25, and 50 micrograms of endotoxin significantly enhanced synthesis of immunoreactive (i) leukotriene (LT)C4/D4 and thromboxane (Tx)B2 (P less than 0.001) as compared to control cells. Endotoxin 5 micrograms/ml produced optimal stimulation of the arachidonic acid metabolites. Calcium ionophore, A23187, significantly enhanced iLTC4/D4 and iTxB2 synthesis more than that elicited with endotoxin. Although phagocytic function was not significantly altered by endotoxin, intracellular killing of C. albicans demonstrated enhanced microbicidal activity at 5 micrograms/ml of endotoxin. Superoxide generation was significantly enhanced in neutrophils stimulated with phorbol myristate acetate (PMA). Endotoxin (5 micrograms/ml) further potentiated superoxide generation by these cells when stimulated by PMA. These findings demonstrate that endotoxin directly enhances neutrophil iLTC4/D4 and iTxB2 synthesis. The enhanced arachidonic acid metabolism elicited by endotoxin in these cells parallels increased microbicidal activity and superoxide generation.

Animals↗
PubMed1985

Susceptibility of some Staphylococcus species to aminoglycosides.

The Staphylococcal strains, identified by "The Simplified Lyogroups System" were tested for their susceptibility to methicillin and some aminoglycosides. The results, besides showing a higher ratio of susceptibility against aminoglycosides in methicillin-susceptible (MS) strains, show a different trend within each lyogroup. A total of 1616 wild Staphylococcus strains were isolated in microbiological units in Catania, Messina, Rome and Genoa. The results show a high susceptibility to aminoglycosides, both in MS and methicillin-resistant (MR) groups but with different trends among lyogroups.

Amikacin↗
PubMed1985

Evidence that prostaglandins within preoptic area (POA) may mediate the antidipsogenic effect of Escherichia coli endotoxin in the rat.

Intravenous injection of Escherichia coli endotoxin (LPS; 640 micrograms/kg) produced an antidipsogenic effect in 48-h water-deprived rats, which was antagonized by acetylsalicylic acid (ASA; 0.45, 0.9 microM) injected directly into cerebral preoptic area (POA). ASA (0.9 microM) when injected into POA did not elicit, by itself, any effect on drinking. Endotoxin (0.5, 1, and 2 micrograms), when injected directly into POA, produced a dose-dependent inhibition of drinking stimulated by water deprivation. This effect was antagonized by ASA (0.45 microM) injected into POA 15 min before LPS. Injection of LPS (2 micrograms) into brain areas not involved in drinking regulation (superior colliculus or nucleus caudatus) was without effect on 48-h water deprivation-induced thirst. PGI2 (5, 50, and 500 ng) injected ino POA showed a dose-dependent antidipsogenic effect on drinking stimulated by water deprivation. The data suggest that prostaglandins, within the preoptic area, might be involved in the antidipsogenic effect of E coli LPS, given either intravenously or directly into POA.

Animals↗
PubMed1984

Shigella sonnei endotoxin reduces arterial blood pressure but does not alter pituitary pro-opiocortin cleavage and corticosterone release in the rat.

Intravenous (iv) bolus injection of 320 and 640 micrograms/Kg of lipopolysaccharides (LPS) of S. sonnei (either in phase I or in phase II) resulted in a dose-dependent decrease in mean arterial pressure, when given in freely moving rats. No changes were observed in plasma beta-endorphin (beta-EP), ACTH and corticosterone levels. Pituitary beta-EP content was not modified 1 h after iv injection of LPS. Data suggest that doses of LPS, which are able to produce reversible hypotension, do not alter pro-opiocortin cleavage and corticosterone release.

Adrenocorticotropic Hormone↗
PubMed1984

Effects of tetanus toxin after intracerebral microinjection are antagonized by drugs enhancing GABAergic transmission in adult fowls.

In adult fowls (Gallus domesticus), the behavioural effects of small doses of tetanus toxin, after unilateral microinjection into the nucleus mesencephalicus profundus (NMP), homologous to the mammalian substantia nigra, were studied. A rich pattern of stereotyped movements, vocalization, ipsilateral head-neck rotation, wing abduction, occasional ipsilateral circling and escape responses from the box were observed; the intensity of such symptomatology was dose-related and fully reversible within approx. 4 hr. Pretreatment with sodium valproate (100 and 200 mg/kg, i.m.) or with ethanolamine-sulphate (EOS, 1.6 mumol into the NMP) completely prevented the effects of tetanus toxin. The present findings show that fowls can represent an ideal species for studying acute central effects of tetanus toxin and more interestingly that drugs enhancing GABAergic mechanisms are able to prevent the effects of tetanus toxin.

Animals↗
PubMed1984

In vitro susceptibility of Salmonella strains to cefotetan and other cephalosporins.

The in vitro activity of cefotetan, a recently developed cephamycin, is investigated by Minimum Inhibitory Concentration (MIC) and by the agar diffusion method against 212 strains of Salmonella (36 species). Cefotetan shows good activity against all strains of Salmonella tested and it is more active than other cephalosporins, in particular, on S. wien.

Cefotetan↗
PubMed1983

Cardiovascular responses of conscious rats to acute intravenous and intracerebroventricular administration of Shigella sonnei endotoxin.

Shigella sonnei lipopolysaccharide (LPS) was injected intravenous (iv) or into the lateral cerebral ventricle (icv) of freely moving rats. Iv injection of 320 micrograms/Kg reduced arterial blood pressure, increased heart rate and did not change pressor response and reflex bradycardia induced by iv bolus injection of phenylephrine (5 micrograms/Kg). Iv injection of 640 micrograms/Kg reduced arterial blood pressure and heart rate, and altered baroreceptor reflexes. Icv injection of LPS (up to 50 micrograms/rat) neither changed resting blood pressure and heart rate nor modified phenylephrine induced pressor response and reflex bradycardia. Results suggest that S. sonnei endotoxin determines cardiovascular changes mainly through baroreceptor resetting. Data also seem to rule out a central nervous system involvement.

Animals↗
PubMed1983

Antidipsogenic effect of endotoxin in the rat.

Escherichia coli LPS (640-1280 mcg/Kg, intravenously) showed a powerful, dose-dependent and long-lasting inhibitory effect on drinking behavior stimulated by 48 h water deprivation, subcutaneous injection of isoprenaline (33.3 mcg/Kg) and intracerebroventricular injection of hypertonic NaCl (2.9%) solution, carbachol (250 ng) and angiotensin II (100 ng). The antidipsogenic effect was neither a consequence of behavioral alterations, nor due to endotoxin peripheral vasodilating activity. Naloxone (60-120-240 mcg/Kg, subcutaneously) did not influence endotoxin inhibition of water intake, thus ruling out an endorphin-mediated effect. When prostaglandin synthesis was inhibited, the effect of endotoxin was reduced. Since prostaglandins do not seem to be involved in the regulation of thirst, the mechanism of the antidipsogenic effect elicited by endotoxin needs further study.

Angiotensin II↗
PubMed1983

Enzyme-linked immunosorbent assay (ELISA) for streptokinase antibodies.

A micro plate Enzyme-linked immunosorbent assay (ELISA), developed for detection of antibodies to Streptokinase, was used to analyze 80 human sera. The aim was to provide a simple method for antibody screening that required neither sophisticated equipment nor a high degree of technological skill. Preliminary results show that ELISA is specific, reproducible and sensitive. Comparative evaluation of the ELISA and the coagulum lysis test for antibodies against streptokinase show excellent correlation. We also evaluated the anti-Streptolysin O titer either by conventional method or ELISA. The sensitivity of ELISA for detecting anti-Streptolysin O antibodies was 3-4-fold higher than that of the hemolytic test. The sensitivity of ELISA for detecting anti-streptokinase antibodies was 10-20-fold higher than that of the coagulum lysis. The Enzyme-linked immunosorbent assay seems to offer some advantages over the more commonly used coagulum lysis test as far as sensitivity is concerned and potentially it is suggested that this method could be usefully employed clinically in human streptococcal infections.

Adult↗
PubMed1982

Cardiovascular effects of Shigella sonnei endotoxin in the rat.

Shigella sonnei lipopolysaccharide (LPS), either in phase I (extracted from the smooth strains), or in phase II (extracted from the rough strains) reduced mean arterial pressure and heart rate following a 640 micrograms/Kg intravenous (iv) bolus injection in the urethane-anesthetized rat. Lower doses were without significant effects. Escherichia coli LPS (640 micrograms/Kg iv) produced a greater and more prolonged hypotension, however the negative chronotropic effect was less severe. The iv injection of the lipid A moiety of the LPS molecule of Shigella sonnei resulted in a more pronounced hypotensive effect than that obtained with the parent LPS, thus showing that lipid A is the vasodilatating fraction of the molecule. When lipid A was injected in rats pretreated with aspirin or with naloxone, the hypotensive effect was significantly reduced and the decrease in heart rate was reverted in tachycardia. In atropine-pretreated, surgically bivagotomized rats, iv injection of lipid A was followed by a long-lasting pressor effect. The date indicate that Shigella sonnei endotoxin has cardiovascular effects, mainly due to its lipid A moiety of the molecule. The hypotensive effect involves a wide range of mechanisms.

Animals↗
PubMed1981

Chromatographic purification from Streptococcus faecium extract of a factor active on Picornaviridae.

"In vitro" antiviral activity against Picornaviridae and the trials for purification from Str. faecium extract of a factor responsible of these effects are reported. Fractionation on Bio-Gel P-150 and on DEAE-cellulose column and analytical methods for protein and aminosugars were used. Present results demonstrate an antiviral activity of Str. faecium extract against Picornaviridae. Virus inhibiting activity is not correlated with the majority of the Folin reacting proteins, which are present in the bacterial extract. No reliable relationship could be detected for aminosugars containing components, since the amount of aminosugar in fraction from Bio-Gel is extremely low and widely distributed.

Antiviral Agents↗
PubMed1981

Behavioural and body temperature effects of meningococcal lipopolysaccharide after intraventricular injection in adult fowls Gallus domesticus.

The effects of the meningococcal lipopolysaccharide (LPS), given into the II cerebral ventricle of adult fowls, were studied on behaviour and body temperature. Immediately after the administration a marked and dose- dependent behavioural sedation or sleep lasting over 2 hours or more according to the dose was observed. The body temperature effects of LPS were biphasic, i.e. and immediate initial phase of hypothermia lasting about 100 min, followed by a longer-lasting fever response. A pretreatment with phentolamine, an antagonist at alpha-adrenoceptors prevented the hypothermic phase following the endotoxin administration. In conclusion, present experiments show that in comparison to 0-somatic antigen of Shigella dysenteriae, meningococcal endotoxin possesses more marked behavioural effects and a different profile in body temperature effects.

Animals↗