Search PubMed⌕ Search

Biomedical subjects

P Rossi

Publications and source records attributed to P Rossi.

At least 163 records · Page 9Linked to original sources
PubMed1999

Interventional radiology in the treatment of urological vascular complications.

Urological vascular complications (UVC) are largely secondary to percutaneous procedures that are nowadays extensevely used by the urologists and the nephrologists. The major frequency of UVC is observed after the renal biopsy, in a percentage varying from 7 to 17% in different series; UVC are less frequent after a nephrostomic procedure (near 1-3%). UVC consist of artero-venous fistulas (AVF) and pseudoaneurysms (PA), that generally cause haemorrhage, particularly macroscopic hematuria. In the vast majority of cases hematuria resolves spontaneously or with conservative therapy but, in the 4 to 9% of patients persists and requires an adequate therapy, often in emergency. Interventional radiology permits an effective and timely treatment of the lesions, using the techniques of transcatheter embolization that are greatly improved in the last 20 years and that present rate of technical success greater than 80%. Moreover radiological embolization shows a low incidence of complications and lower hospitalization cost with respect to surgical treatment. Herein we describe the different techniques of embolization, the indications and the results as appears from the literature and the personal experience. The latter is based on a series of 31 procedures performed in 26 patients, with a rate of technical and clinical success of 93.5%.

Adolescent↗
PubMed1999

[Revascularization of the corpora cavernosa in vasculogenic impotence].

The vasculogenic erectile impotence, caused by occlusion and/or stenosis of arteries supplying the penis, is the most common cause of erectile failure in men over 40 years. The vasculogenic impotence is more found by peripheral vasculopathies like diabetes mellitus and nicotine abuse. It is important that the precise site of vascular lesion is established with selective arteriography of the hypogastric-internal pudendal axis. The specific aim of surgery is to increase the cavernosal arterial perfusion pressure and blood inflow in patients with vasculogenic erectile dysfunction secondary to pure arterial insufficiency. There have been multiple revascularization techniques described for the treatment of proximal or distal occlusion with variable results. Microsurgery is important for distal lesions and we think that the best candidates for the Michal II procedure seem to be those with localized obstruction of the internal pudendal, while venous arterialization is the preferred procedure for patients with pathological cavernous or dorsal penile arteries. In this paper the most important procedures to restore physiological erection are presented; however no single revascularization procedure has been generally accepted as a definitive answer to this problem. There is a need for further prospective studies with longer follow-up and more objective investigations.

Erectile Dysfunction↗
PubMed1999

[Optimization of dosage and exam technique in the use of oral contrast media in magnetic resonance].

PURPOSE: Aim of our study was to optimize the dose, scan delay and sequences for use in MR studies with an oral contrast agent (FerriSeltz, Bracco, Milan, Italy) to obtain positive or negative contrast enhancement in the bowel lumen. MATERIAL AND METHODS: In vitro: 10 mL vials with increasing concentrations (10-100 mg/mL) of the agent, containing 200 mg ferric ammonium citrate/g, were studied with a 1.5 T magnet (Philips NT, The Netherlands), by acquiring T2-weighted STIR and TSE and T1-weighted TFE sequences. Signal intensity was compared by using a ROI. In vivo: 16 volunteers were examined with the same sequences at 20 minutes and 2 hours after the oral administration of 6-27 g of the product diluted in 600 mL water. Images were analyzed by two radiologists and scored on a 4-point scale based on signal intensity; results were compared with Student's "t"-test. RESULTS: In vitro: MR signal was always hyperintense on T1-weighted images, as well as on T2-weighted TSE and SPIR images at concentrations lower than 45 mg/mL. Hypointense signal was seen on T2-weighted TSE and SPIR images at higher concentrations and on STIR sequences at 10-20 mg/mL concentrations. In vivo: the bowel exhibited positive enhancement on T1-weighted TFE and T2-weighted TSE and SPIR images 20 minutes after contrast agent administration at concentrations lower than 45 mg/mL. At 2 hours, bowel loops were hypointense on T2-weighted TSE and SPIR images at 15-20 mg/mL concentrations. STIR images showed hypointense bowel loops at both 20 minutes and 2 hours after 10-20 mg/mL contrast agent administration. Quantitative analysis showed a statistically significant superiority (p < .05) of T2-weighted STIR images in providing negative opacification of the bowel lumen. CONCLUSIONS: Ferric ammonium citrate, being a positive or negative contrast agent according to its dilution, permits to tailor the dose to optimize bowel lumen opacification.

Administration, Oral↗
PubMed1999

[Paradoxical pulmonary embolism. A rare complication of arteriovenous fistulization of an aorto-iliac aneurysm].

Aneurysms of the infra-renal abdominal aorta or iliac arteries result in ilio-caval compression in about 10% of cases which may cause venous thrombosis by stasis and pulmonary embolism. Fistulisation of these aneurysms into the inferior vena cava or an iliac vein is rare and paradoxical pulmonary embolism from arterial thrombus of the aneurysmal pouch is exceptionally rare. The authors report a new case in which the ilio-iliac arteriovenous fistula caused high output cardiac failure, ischaemia of the homolateral leg and pulmonary embolism. Doppler ultrasonography diagnosed the fistula and excluded a deep vein thrombosis. This case illustrated the essential value of clinical examination and of Doppler ultrasonography, especially of the abdomen, in the investigation of the causes of pulmonary embolism.

Aged↗
PubMed1998

Zidovudine therapy and HIV type 1 mutations in children with symptomatic HIV type 1 infection: effect of switching to didanosine or zidovudine plus didanosine therapy. Italian Multicenter Study Group on HIV Mutations in Children.

Type and prevalence of zidovudine (ZDV) resistance mutations in HIV-1-infected children in clinically stable condition and on ZDV monotherapy were analyzed to evaluate the effect of switching to didanosine (ddI) monotherapy or to ZDV plus ddI on the pattern of mutations and on the clinical outcome. Monthly clinical and laboratory controls for HIV-1 infection status were performed; at enrollment and every 4 to 6 months after treatment randomization mutant proviral sequences were evaluated in all the children, whereas viral burden was performed only in a small subgroup of patients randomly selected in each of the three treatment groups. ZDV resistance-associated proviral DNA mutations were defined as low-level resistance (LLR) mutations or medium/high-level resistance (MHLR) mutations; clinical outcome was considered as stable or deteriorating. Results showed that at entry into the study the duration of ZDV therapy was significantly correlated with the presence of mutations, and that the level of resistance given by mutations was associated with the severity both of symptoms and immunodeficiency. After randomization to treatment, in patients with mutations that confer LLR a better clinical outcome with ddI monotherapy than with ZDV plus ddI and ZDV alone was observed in the subsequent 6 months, whereas in patients with mutations that confer MHLR no significant difference among the three treatment groups was found. Data showed also that levels of viral burden at the time of changing therapy are related to clinical outcome if measured by plasma viral load. These results suggest that genotypic resistance assays, together with viral load, may prove useful for rational treatment decisions both at the start of therapy and with failure.

Anti-HIV Agents↗
PubMed1998

Stomach distension increases efferent muscle sympathetic nerve activity and blood pressure in healthy humans.

Although the enteric nervous system is usually described as a separate and independent entity, animal studies show that gastric distension causes a reflex increase in arterial pressure and a sympathetically mediated increase in heart rate and peripheral vascular resistance. To assess the influence of gastric distension on sympathetic outflow and blood pressure, we recorded muscle sympathetic nerve activity (MSNA) from the peroneal nerve by microneurography in eight healthy volunteers. The stomach was distended by means of a barostat, using a single staircase protocol by which pressure was increased by 2 mmHg every 3 min. Gastric sensory function was assessed at each distension step by using a visual analog scale (VAS) for sensations of fullness, nausea and pain. For comparison, we also performed a cold pressor test. The MSNA increased on barostat-induced gastric distension with an almost concomitant elevation of blood pressure. The increase in both was proportional to the intragastric pressure and both decreased towards initial values after the end of distension. Heart rate increased inconsistently and only at higher distension pressures that were associated with high VAS scores. The opposite was found for the cold pressor test. The results of this study confirm the existence of a functional relationship between gastrointestinal distension and cardiovascular function. Decrease in this gastrovascular response may play a role in postprandial hypotension in the elderly, since the MSNA responses to simulated microgravity decrease with age.

Adult↗
PubMed1998

Analysis of HIV-1 reverse transcriptase gene mutations in infected children treated with zidovudine.

Prolonged treatment with antiretroviral agents directed against reverse transcription (RT) in patients with HIV-1 infection results in the emergence of virus variants with reduced sensitivity containing mutations in the HIV-1 RT gene. Development of zidovudine (ZDV)-related mutations was studied in a cohort of 24 vertically infected pediatric patients receiving ZDV therapy. Monthly clinical and immunologic evaluation was accompanied by direct sequencing of the HIV-1 RT gene every 4 months. A correlation was observed between the emergence of mutations and the duration of therapy. Mutation at codon 41 was found only in the presence of mutation at codon 215. The presence of the mutations Met41-->Leu and Thr215-->Tyr/Phe did not appear to be related to disease progression. These findings suggest that the mere presence of mutations in the HIV-1 RT gene alone during ZDV monotherapy is not a reliable prognostic marker in the absence of other clinical and virologic information.

Anti-HIV Agents↗
PubMed1998

Involvement of phospholipase Cgamma1 in mouse egg activation induced by a truncated form of the C-kit tyrosine kinase present in spermatozoa.

Microinjection of a truncated form of the c-kit tyrosine kinase present in mouse spermatozoa (tr-kit) activates mouse eggs parthenogenetically, and tr-kit- induced egg activation is inhibited by preincubation with an inhibitor of phospholipase C (PLC) (Sette, C., A. Bevilacqua, A. Bianchini, F. Mangia, R. Geremia, and P. Rossi. 1997. Development [Camb.]. 124:2267-2274). Co-injection of glutathione-S-transferase (GST) fusion proteins containing the src-homology (SH) domains of the gamma1 isoform of PLC (PLCgamma1) competitively inhibits tr-kit- induced egg activation. A GST fusion protein containing the SH3 domain of PLCgamma1 inhibits egg activation as efficiently as the whole SH region, while a GST fusion protein containing the two SH2 domains is much less effective. A GST fusion protein containing the SH3 domain of the Grb2 adaptor protein does not inhibit tr-kit-induced egg activation, showing that the effect of the SH3 domain of PLCgamma1 is specific. Tr-kit-induced egg activation is also suppressed by co-injection of antibodies raised against the PLCgamma1 SH domains, but not against the PLCgamma1 COOH-terminal region. In transfected COS cells, coexpression of PLCgamma1 and tr-kit increases diacylglycerol and inositol phosphate production, and the phosphotyrosine content of PLCgamma1 with respect to cells expressing PLCgamma1 alone. These data indicate that tr-kit activates PLCgamma1, and that the SH3 domain of PLCgamma1 is essential for tr-kit-induced egg activation.

Adaptor Proteins, Signal Transducing↗
PubMed1998

The weaver mutation causes a loss of inward rectifier current regulation in premigratory granule cells of the mouse cerebellum.

Considerable interest has recently focused on the weaver mutation, which causes inward rectifier channel alterations leading to profound impairment of neuronal differentiation and to severe motor dysfunction in mice (Hess, 1996). The principal targets of mutation are cerebellar granule cells, most of which fail to differentiate and degenerate in a premigratory position (Rakic and Sidman, 1973a,b). Two hypotheses have been put forward to explain the pathogenetic role of mutant inward rectifier channels: namely that inward rectifier channel activity is either lacking (Surmeier et al., 1996) or altered (Kofuji et al., 1996; Silverman et al., 1996; Slesinger et al., 1996). We have examined this question by recording inward rectifier currents from cerebellar granule cells in situ at different developmental stages in wild-type and weaver mutant mice. In wild-type mice, the inward rectifier current changed from a G-protein-dependent activation to a constitutive activation as granule cells developed from premigratory to postmigratory stages. In weaver mutant mice, G-protein-dependent inward rectifier currents were absent in premigratory granule cells. A population of putative granule cells in the postmigratory position expressed a constitutive inward rectifier current with properties compatible with mutated GIRK2 channels expressed in heterologous systems. Because granule cells degenerate at the premigratory stage (Smeyne and Goldowitz, 1989), the loss of inward rectifier current and its regulation of membrane potential are likely to play a key role in the pathogenesis of weaver neuronal degeneration.

Anesthetics, Local↗
PubMed1998

Proton release upon glutathione binding to glutathione transferase P1-1: kinetic analysis of a multistep glutathione binding process.

The fate of the thiol proton coming from the ionization of the sulfhydryl group of GSH in the active site of glutathione transferase P1-1 has been studied. pH changes caused by the binding of GSH to the enzyme in the absence of any inorganic buffer indicate that the thiol proton leaves the active site when the binary complex is formed. The amount of protons released is stoichiometric to the amount of GSH thiolate formed in the G-site. The apparent pKa value for the bound GSH, calculated with this potentiometric approach, is 6.18 +/- 0.09; very similar values are found by spectrophotometric (6.20 +/- 0.12) and by kinetic (6.00 +/- 0.08) experiments. Binding of S-hexylglutathione does not cause any proton release. Stopped-flow data obtained by means of an acid-base indicator show that the proton extrusion process (apparent t1/2 = 1.1 +/- 0.1 ms at 15 degrees C) is not rate limiting in turnover (apparent t1/2 = 34 +/- 4 ms at 15 degrees C). By comparing the kinetic behavior of three distinct events occurring during the binding of GSH to the enzyme, i. e., proton release, ionization of bound GSH and quenching of intrinsic fluorescence, it appears that the binding process follows a multistep mechanism possibly involving the conformational transition of a weak precomplex into the final Michaelis complex. This step is modulated by helix 2 motions and may be rate limiting at physiological GSH concentrations. These findings, coming from kinetic studies, are consistent with NMR data [Nicotra, M., Paci, M., Sette, M., Oakley, A. J., Parker, M. W., Lo Bello, M., Caccuri, A. M., Federici, G., and Ricci, G. (1998) Biochemistry 37, 3020-3027] and time-resolved fluorescence experiments [Stella, L., Caccuri, A. M., Rosato, N., Nicotra, M., Lo Bello, M., De Matteis, F., Mazzetti, A. P., Federici, G., and Ricci, G., manuscript in preparation].

Glutathione↗
PubMed1998

Distribution of Trichinella spiralis larvae in muscles from a naturally infected horse.

Epidemiological investigations conducted during 10 trichinellosis outbreaks between 1975 and 1994 showed that horse-meat was the probable source of infection. Though hundreds of thousands of horses have been examined at abattoirs in America and Europe to detect Trichinella infection by artificial digestion or trichinelloscopy, an infected horse has never been detected during routine analysis, which consists of examining 1 g of tissue muscle from the diaphragm. In November 1996, a naturally infected horse imported from Romania was detected in Southern Italy. The parasite was identified as Trichinella spiralis by random amplified polymorphic DNA analysis. Artificial digestion of tissue samples from 60 different muscles from 13 different sites of the infected horse carcass showed that M. levator Labii maxillaris, M. hyoideus transversus, and M. buccinator were the 3 most infected muscles. Muscles from the tongue, the masseter, and the diaphragm, which have normally been considered the muscles of choice for diagnosis, were the 4th, 6th and 13th most infected muscles, respectively. When comparing body sites, muscle tissues from the head showed the highest level of infection, followed by muscles from the neck. This finding may explain the negative results that have been obtained in the past during routine examination of the diaphragm of horses.

Abattoirs↗
PubMed1998

Transjugular intrahepatic portosystemic shunt versus endoscopic sclerotherapy for the prevention of variceal bleeding in cirrhosis: a randomized multicenter trial. Gruppo Italiano Studio TIPS (G.I.S.T.).

Transjugular intrahepatic portosystemic shunt (TIPS), a new technique for the treatment of portal hypertension, has been successful in preliminary studies to treat acute variceal hemorrhage and to prevent variceal rebleeding. The purpose of this multicenter, randomized controlled trial is to compare the efficacy of TIPS with that of endoscopic sclerotherapy in the prevention of variceal rebleeding in cirrhosis. Eighty-one cirrhotic patients, with endoscopically proven variceal bleeding, were randomized to either TIPS (38 patients) or endoscopic sclerotherapy (43 patients). Randomization was stratified according to the following: if bleeding occurred < 1 week (stratum I); if bleeding occurred 1 to 6 weeks (stratum II); and if bleeding occurred 6 weeks to 6 months (stratum III) before enrollment. Follow-up included clinical, biochemical, Doppler Ultrasound, and endoscopic examinations every 6 months. During a mean follow-up of 17.7 months, 51% of the patients treated with sclerotherapy and 24% of those treated with TIPS rebled (P = .011). Mortality was 19% in sclerotherapy patients and 24% in TIPS patients (P = .50). Hepatic encephalopathy (HE) developed in 26% and 55%, respectively (P = .006). A separate analysis of the three strata showed that TIPS was significantly more effective than sclerotherapy (P = .026) in preventing rebleeding only in stratum I patients. TIPS is significantly better than sclerotherapy in preventing rebleeding only when it is performed shortly after a variceal bleed; however, TIPS does not improve survival and is associated with a significantly higher incidence of HE. The overall performance of TIPS does not seem to justify the adoption of this technique as a first-choice treatment to prevent rebleeding from esophageal varices in cirrhotic patients.

Aged↗