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Biomedical subjects

G Sironi

Publications and source records attributed to G Sironi.

At least 37 records · Page 2Linked to original sources
PubMed1997

Pharmacological characterization of the uroselective alpha-1 antagonist Rec 15/2739 (SB 216469): role of the alpha-1L adrenoceptor in tissue selectivity, part II.

The aim of the present work was to investigate whether or not the uroselectivity of Rec 15/2739 and several other alpha-1 adrenoceptor (alpha1-AR) antagonists observed in the anesthetized dog could be related to selectivity of these compounds for a particular alpha-1 AR subtype. The binding affinity of the tested compounds for canine prostate alpha-1 ARs and their in vitro functional affinity for the alpha-1 ARs of rabbit urethra and prostate correlated with their functional affinity for the alpha-1L AR subtype, but not with the binding affinity for recombinant animal and human alpha-1a, alpha-1b and alpha-1d AR subtypes. Similar results were obtained when the in vivo potency on urethral pressure was correlated with the affinity for the alpha-1 AR subtypes; also in this case alpha-1L AR gave the best correlation. No correlation was obtained by considering the other alpha-1 AR subtypes. The in vivo hypotensive effects observed in dog after i.v. administration of the considered compounds correlated only with the binding affinity for the animal and human alpha-1d subtype. In conclusion, the results shown in the present paper indicate that the potencies of different alpha-1 antagonists against the contractions induced by norepinephrine on tissues of the lower urinary tract of rabbits and dogs are better correlated with their affinity for the putative alpha-1L subtype than for the alpha-1a subtype. Only the compounds showing selectivity for the alpha-1L subtype versus the alpha-1d subtype proved highly selective in vivo for the lower urinary tract versus the vascular tissues.

Adrenergic alpha-Antagonists↗
PubMed1996

Growth hormone but not prolactin concentrations in the fluid of bovine ovarian cysts are related to the cystic stage of luteinization.

Regulation of follicular growth and ovulation as well as steroid production by the ovary depends principally on gonadotropins. However nonsteroid systemic hormones and autocrine and paracrine factors contribute to the regulation of ovarian function. The objectives of the present work were 1) to asses the presence of growth hormone (GH) and prolactin (PRL) in fluid drawn from normal bovine ovarian follicles, cysts or cystic corpora lutea; 2) to relate the stage of luteinization of the cyst with the GH and PRL concentrations in fluids; and 3) to asses the feasibility of providing a defined nonsteroid hormone marker to distinguish between normal and pathological ovarian structures. Cysts were classified according to histological and morphological appearance as follicular or luteal. Concentrations of GH, PRL, estrogens (E2), progesterone (P4) and testosterone (T) were measured in follicular and cystic fluids. On the basis of the E2 to P4 ratio, ovarian formation classes were further divided into two subclasses (E2 dominant and P4 dominant). The results provide evidence of 1) the presence of immunoreactive GH and PRL in all the follicular and cystic fluids assayed, 2) an increasing concentration of GH correlated to the stage of luteinization of the cyst and a direct correlation between GH and P4 concentrations, 3) a significant variability of intraovarian fluid PRL concentration not related to the histological class of the cyst nor to the concentrations of steroid hormones examined, and 4) the possibility of distinguishing 6 different ovarian formation classes by merely measuring GH, P4, E2 and T concentrations in fluids. These data contribute to a better understanding of the endocrine milieu of bovine ovarian cystic degeneration.

Journal Article↗
PubMed1996

An outbreak of Pacheco's parrot disease in psittacine birds recently imported to Campania, Italy: isolation of psittacid herpesvirus 2.

The authors describe an outbreak of Pacheco's Parrot Disease (PPD) which occurred in Italy in recently imported psittacine birds and was caused by Psittacid Herpesvirus type 2 (PsiHV2). The authors stress the different susceptibility to the disease in the species involved. This outbreak showed the failure of the vaccine prophylaxis that had been administered to the birds with ordinary commercial preparations containing Psittacid Herpesvirus type 1. The authors emphasize the necessity of producing a vaccine containing inactivated viruses of all known serotypes.

Animals↗
PubMed1996

Antihypertensive effects of lercanidipine in experimental hypertensive rats and dogs.

The antihypertensive action of lercanidipine (CAS 132866-11-6, Rec 15/2375), a new 1,4-dihydropyridine (1,4-DHP) calcium entry blocker (CEB), was examined in spontaneously hypertensive rats (SHR) and renal hypertensive dogs after acute and repeated administration, in comparison to several reference 1,4-DHPs. In acute experiments in SHR, lercanidipine reduced diastolic blood pressure showing a potency similar to felodipine and 2-3 fold higher than those of nicardipine and nitrendipine, after both intravenous and oral administration. Analysis of the area under the curves of percent reduction of diastolic blood pressure exerted for 3 and 8 h after intravenous and oral administrations, respectively, showed that the duration of the antihypertensive effect of lercanidipine was longer than that of the reference dihydropyridines. After repeated administrations to SHR no tachyphylaxis was observed, as indicated by the marked and persistent decrease in systolic blood pressure elicited by lercanidipine, given orally once a day for 21 days. Moreover, starting from the first week of treatment, the daily basal values of systolic blood pressure of the rats treated with lercanidipine were significantly lower than those of the placebo-treated group. In renal hypertensive dogs, after acute oral administration, lercanidipine was as potent as nitrendipine. After repeated administration, the action of lercanidipine was longer lasting than that of nicardipine and no decrease in the antihypertensive effects was observed. The in vivo studies show that lercanidipine has a potent and long-lasting antihypertensive profile, suggesting that this compound may be used for once-a-day treatment.

Administration, Oral↗
PubMed1996

Haemodynamic effects of lercanidipine in anaesthetized open-chest dogs.

In this study, the haemodynamic effects of lercanidipine (CAS 132866-11-6, Rec 15/2375) in anaesthetized open-chest dogs were investigated in comparison with nitrendipine. Intravenously administered lercanidipine induced a dose-related, long-lasting reduction in systemic and coronary vascular resistances, with concomitant decrease in arterial blood pressure and increase in coronary blood flow. The hypotensive ED25 was 6.1 micrograms/kg and 4.2 micrograms/kg (decrease of mean blood pressure and of total peripheral resistances, respectively) and the ED50 on coronary vasodilation, 4.8 micrograms/kg 7.8 micrograms/kg (increase of coronary blood flow and decrease in coronary vascular resistances, respectively). The time-course of the haemodynamic effects was investigated after administration of 5 micrograms/kg. A slow onset of haemodynamic vasodilation and long-lasting activity were observed, since peak effects on mean blood pressure and coronary blood flow occurred at 20 and 30 min after the administration, respectively, and the effects on systemic and coronary resistances were still significant at 30 and 150 min after administration, respectively. A reflex, non-dose-dependent increase in heart rate was observed after the administration of 10 and 30 micrograms/kg, which was absent with the 5 micrograms/kg dose. As far as cardiac contractility was concerned, the contractile index dP/dtmax and dP/dt/P were analyzed. In the dose-response study, dP/dtmax was practically not affected. In the time-course study, dP/dtmax was not modified after administration of 5 micrograms/kg, and dP/dt/P showed a slight but long-lasting increase. Haemodynamic investigation confirmed in vivo the high vascular selectivity of lercanidipine and a lack of sympathetic reflex activation at vasodilating doses.

Anesthesia↗
PubMed1995

Immunity determinant of phage-plasmid P4 is a short processed RNA.

In the phage-plasmid P4, both lysogenic and lytic functions are coded by the same operon. Early after infection the whole operon is transcribed from the constitutive promoter PLE. In the lysogenic condition transcription from PLE terminates prematurely and only the immunity functions, which are proximal to the promoter, are thus expressed. Fragments of the P4 immunity region were cloned in an expression vector. A DNA fragment as short as 91 bp was sufficient, when transcribed, to express P4 immunity and to complement P4 immunity deficient mutants. This fragment, like prophage P4, produced a 69 nt long RNA (CI RNA). A shorter P4 fragment neither expressed immunity nor synthesized the CI RNA. Thus the CI RNA is the P4 trans-acting immunity factor. The 5' end of the CI RNA, mapped by primer extension, does not correspond to the transcription initiation point, thus suggesting that the CI RNA is produced by processing of the primary transcript. In an RNase P mutant host the processing of the 5' end and the production of a functional CI RNA were impaired. The requirement of RNase P for the correct processing of CI appears to be related to the predicted secondary structure of the precursor CI RNA. A region (seqB) within the CI RNA shows complementarity with two cis-acting sequences (seqA and seqC) required for P4 immunity, suggesting that transcription termination may be caused by pairing of the CI RNA with the complementary target sequences on the nascent transcript.

Base Sequence↗
PubMed1992

Genetic analysis of the immunity region of phage-plasmid P4.

In the prophage P4, expression of the early genes is prevented by premature termination of transcription from the constitutive promoter PLE. In order to identify the region coding for the immunity determinant, we cloned several fragments of P4 DNA and tested their ability to confer immunity to P4 superinfection. A 357 bp long fragment (P4 8418-8774) is sufficient to confer immunity to an infecting P4 phage and to complement the immunity-defective P4 cl405 mutant, both in the presence and in the absence of the helper phage P2. The immunity region covers PLE and the cl locus. We were unable to obtain evidence of translation of the region, thus we suggest that P4 immunity is not elicited by a protein but by a transcript (or transcripts) encoded by the region downstream of the promoter PLE. The promoter PLE appears to be necessary for the expression of P4 immunity: fragments in which the PLE region is deleted did not complement P4 cl405 for lysogenization, although they still interfered with P4 growth. Two complementary sequences downstream of PLE (seqA and seqB) at the 5' and 3' ends of the immunity region play an essential role in the control of P4 immunity.

Base Sequence↗
PubMed1992

Bacteriophage P4 immunity controlled by small RNAs via transcription termination.

Satellite bacteriophage P4 immunity is encoded within a short DNA region 357 bp long containing the promoter PLE and 275 bp downstream. PLE is active both in the early post-infection phase, when genes necessary for P4 lytic cycle are transcribed from this promoter, and in the lysogenic condition, when expression of the above genes is prevented by prophage immunity. In order to understand how P4 immunity is elicited, we have characterized the transcription pattern during the establishment and the maintenance of the satellite phage P4 lysogenic condition. We found that prophage transcription starting at PLE ends prematurely and the transcripts do not extend beyond 300-400 nucleotides downstream of PLE. Thus P4 immunity acts by causing premature transcription termination rather than by repressing transcription initiation. The P4 immunity region is transcribed in the prophage, but it does not seem to be translated; this region contains two elements (seqA and seqB) of a palindromic sequence. In addition to transcripts about 300 nucleotides long, P4 prophage produces a family of shorter transcripts, about 80 nucleotides long, containing seqA or seqB. Evidence is presented suggesting that SeqB RNA is the trans-acting immunity factor, and that interaction of SeqB RNA with the complementary nascent RNA containing seqA may be involved in bringing about premature transcription termination.

Coliphages↗
PubMed1992

Papillomavirus infection in greenfinches (Carduelis chloris).

The present report describes transmissible papillomatous digital lesions observed in two greenfinches (Carduelis chloris) living in a private aviary. The disease appeared in the male bird and successively in the female but did not affect other passerine and psittacine species living with the sick birds. Negative contrast electron microscopy revealed the presence of 52.6 nm virus particles similar to papillomavirus. Immunoelectronmicroscopy confirmed the presence of Papillomavirus genus specific structural antigens in the virus observed.

Animals↗
PubMed1991

Acute hepatosis in the European brown hare (Lepus europaeus) in Italy.

Since October 1986 an unusually high mortality has been observed both in wild European brown hares (Lepus europaeus) and in hare farms in Italy. Pathological alterations, including severe hepatosis, nephrosis, congestion and hemorrhages of tracheal mucosa and lungs, and splenic vascular congestion, were observed in 179 of 381 hares necropsied from 1986 to 1988. Jaundice also was seen in 30% of these hares. Histologically, the liver damage was characterized by coagulative necrosis, mainly located around the portal areas, or by degenerative changes. Hyperemia, focal hemorrhages and periportal mononuclear cell infiltration were also present. The epithelium of renal tubules showed the presence of various degrees of vacuolar degeneration and necrosis, and eosinophilic granular hyaline casts or homogenous proteinaceous material were found within the lumen of tubules. Only the adult hares were affected. In wild hare populations night counts revealed a reduction of the number of observed wild hares during the winter period which ranged from 27 to 40%, whereas in hare farms the mortality ranged from 30 to 90%. Bacteriological, parasitological, and toxicological investigations were unable to confirm the primary cause of these deaths. Negative stain electron microscopy and immunoelectronmicroscopy conducted since October 1988 on liver and spleen homogenates from hares with acute hepatosis revealed the presence of viral particles with morphological aspects resembling those of calicivirus, antigenically related to the etiological agent of viral haemorrhagic disease of rabbits.

Acute Disease↗
PubMed1990

Immunohistochemical detection of papillomavirus structural antigens in animal hyperplastic and neoplastic epithelial lesions.

One hundred and seventy-two hyperplastic and neoplastic epithelial lesions from 8 different mammalian and 1 avian species have been tested with an immunohistochemical technique to detect papillomavirus structural antigens. Selected lesions were diagnosed histologically as papilloma, fibropapilloma, equine sarcoid, squamous cell carcinoma, basalioma, epulis, keratoacanthoma, trichoepithelioma, pilomatrixoma, epidermal inclusion cyst, and hyperkeratotic or acanthotic epidermal lesions. Positive nuclear staining was detected in 14 out of 23 papillomas, 8 out of 32 fibropapillomas and in 1 out of 3 hyperplastic epidermal lesions. Positive samples were found in 5 of 8 mammalian species. Selected samples were also examined by transmission electron microscopy. In 4 samples papillomavirus was seen. In two other samples, negative with immunoperoxidase technique, papovavirus-like particles were observed.

Animals↗
PubMed1990

Nonessential region of bacteriophage P4: DNA sequence, transcription, gene products, and functions.

We sequenced the leftmost 2,640 base pairs of bacteriophage P4 DNA, thus completing the sequence of the 11,627-base-pair P4 genome. The newly sequenced region encodes three nonessential genes, which are called gop, beta, and cII (in order, from left to right). The gop gene product kills Escherichia coli when the beta protein is absent; the gop and beta genes are transcribed rightward from the same promoter. The cII gene is transcribed leftward to a rho-independent terminator. Mutation of this terminator creates a temperature-sensitive phenotype, presumably owing to a defect in expression of the beta gene.

Alleles↗
PubMed1989

Adenoviral fibrinous enteritis in calves.

Two calves coming from different herds showed at post-mortem examination a fibrinous enteritis with mucosal necrosis particularly in the ileal-colonic tract. Histologically, amphophilic intranuclear inclusion bodies were the main feature. They were located in the endothelial cells of the intestine and mesenteric lymph cells. Ultramicroscopic examination of the inclusion bodies revealed the presence of an adenovirus. In one case the virus was isolated on cell cultures and further classified as bovine adenovirus type 4.

Adenoviridae Infections↗
PubMed1989

[Episodes of amyloidosis in young hens after repeated use of antibacterial oil emulsion vaccines].

Outbreaks of systemic amyloidosis with moderate to high mortality in two young layer flocks are described. In both the cases anamnesis reported repeated vaccinations with oil-emulsified bacterins. Grossly, the liver was enlarged, friable and pale. Hepatic rupture and haemorrhages were frequently seen. Moreover heavy granulomatous reactions at the inoculation site was observed. Histologically amyloid deposition was present in the liver and the spleen of the animals from both of the flocks. Histochemical reactions confirm that it is type AA amyloidosis.

Amyloidosis↗