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L Sironi

Publications and source records attributed to L Sironi.

30 records · Page 2Linked to original sources
PubMed1997

Cloning of a single-chain variable fragment (scFv) switching active plasminogen activator inhibitor-1 to substrate.

Increased levels of plasminogen activator inhibitor-1 (PAI-1) are a well-known risk for cardiovascular diseases. A significant number of investigations are aimed at lowering plasma levels of PAI-1 to enhance endogenous fibrinolysis. We have recently generated monoclonal antibodies that neutralize PAI-1 activity by switching the inhibitory conformation to a substrate conformation. However, intact murine antibodies have quite some disadvantages for therapeutic use in man. In the current study, we describe the construction of a smaller antibody fragment derived from a monoclonal antibody (MA-8H9D4) with PAI-1 neutralizing properties. The cDNAs encoding the variable domains of the heavy and light chain were amplified, linked and cloned into a phagemid vector. Resulting clones were expressed as a single-chain variable fragment (scFv, VH-(Gly4Ser)3-VL) on the surface of a phage and selected for binding to PAI-1. Subsequently, a positive phage was used for the production of soluble scFv-8H9D4. Following purification, the characteristics of the scFv-8H9D4 were compared to those of the original MA-8H9D4. The scFv inhibited PAI-1 activity to a similar extent as MA-8H9D4 and by a similar mechanism, i.e., induction of a conformational switch. Thus, this smaller antibody fragment, exhibiting the same properties as the parent molecule may constitute a useful starting point for the design of PAI-1 neutralizing therapeutics.

Animals↗
PubMed1996

Cerebral artery blood flow in relation to age and menopausal status.

OBJECTIVE: To investigate vascular reactivity in women's cerebral arteries from reproductive age to postmenopause. METHODS: The pulsatility index (PI) was measured cross-sectionally in the internal carotid and middle cerebral arteries of 120 women, using a Doppler ultrasound system. Fifteen women were enrolled in each of eight 5-year intervals, spanning ages 20-59 years. RESULTS: In the population as a whole, there was a slight but statistically significant correlation between age and the PI in both arteries, but not after excluding postmenopausal subjects. A significant correlation was found between PI and months since menopause (but not chronologic age) in the postmenopausal women. There was also a statistically significant difference in the PI values for both arteries between pre- and postmenopausal women of similar age. CONCLUSION: Menopause causes a significant increase in the PI of women's cerebral arteries. In postmenopausal women, there is a significant correlation between the PI of the internal carotid and middle cerebral arteries and menopausal but not chronologic age. This effect may be one of the mechanisms by which menopause is associated with the known higher risk for coronary heart disease observed in women.

Adult↗
PubMed1996

Plasminogen activator inhibitor type-1 synthesis and mRNA expression in HepG2 cells are regulated by VLDL.

The effect of VLDL on plasminogen activator inhibitor type 1 biosynthesis in HepG2 cells was investigated. Exposure of HepG2 cells to VLDL (range, 10 to 100 micrograms protein per milliliter) for 16 hours resulted in an enhanced release of PAI-1 antigen and PAI activity into conditioned medium, accompanied by the accumulation of intracellular triglycerides. By using a monoclonal antibody (IgG C7) specific to the LDL receptor, we showed that the effect of VLDL is mediated by its interaction with the LDL receptor. Enhanced PAI-1 release was due to increased biosynthesis: PAI-1 mRNA was doubled, mainly because of the effect on the 2.2-kb PAI-1 mRNA rather than the 3.2-kb transcript. Addition of insulin with the VLDL further enhanced PAI-1 antigen release and PAI-1 mRNA accumulation. The effect of VLDL on steady state levels of PAI-1 mRNA was apparently not due to an increase of gene transcription but to stabilization of both PAI-1 mRNA transcripts. The enhancing effect of VLDL on PAI-1 biosynthesis in HepG2 cells may raise PAI-1 antigen levels not only in hypertriglyceridemic states but also in those conditions in which both insulin and VLDL are elevated.

Carcinoma, Hepatocellular↗
PubMed1994

Complete testicular feminization with normal gonadotropin and high androgen secretion: a case report.

A patient with a complete form of testicular feminization with normal gonadotropin and high testosterone levels is described here. These findings are in contrast to previous reports that have shown high circulating luteinizing hormone (LH) levels in adults affected by this syndrome. Testicular histology revealed tubular atrophy and hyperplastic Leydig cells which are in accordance with the high testosterone levels and the difficulty in visualization of the testes. Because of the increased risk of gonadal malignancy, a laparoscopic gonadectomy was performed.

Adult↗
PubMed1993

Organ-specific autoimmunity in patients with premature ovarian failure.

The diagnosis of premature ovarian failure (POF) was made in 45 women (aged 14 to 39 yr) with high concentrations of FSH and LH. Sera from these patients and a control group of 28 women were used to detect organ-specific autoantibodies. Eighteen patients with POF (40%) were positive for at least one autoantibody. In the control group only one woman (3.6%) showed autoimmunity. Antithyroid was the most representative autoimmunity (20%) in the POF group. By indirect immunofluorescence, only one patient was positive for antiovarian and antiadrenal antibodies. In summary, the results of this study are consistent with previous immunohistochemical data which indicate that autoimmune disorders are common in patients with POF. Furthermore, the detection of antiovarian antibodies in only one patient confirms that they are probably detectable in a short period of the disease.

Adolescent↗
PubMed1993

Increased synthesis of plasminogen activator inhibitor-1 by cultured human endothelial cells exposed to native and modified LDLs. An LDL receptor-independent phenomenon.

The effects of native and acetylated low density lipoproteins (LDLs and acetyl-LDLs, respectively) on the release of plasminogen activator inhibitor type 1 (PAI-1) by cultured human umbilical vein endothelial cells (ECs) were evaluated. LDL and acetyl-LDL incubated with ECs for 16-18 hours increased the PAI-1 antigen levels in conditioned medium. At a concentration of 100 micrograms/mL, LDL and acetyl-LDL increased PAI-1 by 10.8 and 12.0 ng/mL, respectively (p < 0.05 and p < 0.01 versus control). The increases in PAI-1 antigen levels exerted by the lipoproteins paralleled the changes in PAI-1 activity. The effect of LDL and acetyl-LDL was concentration dependent and specific for PAI-1 because tissue-type plasminogen activator and expression of procoagulant activity were not affected by either lipoprotein. In addition, total protein synthesis evaluated in [35S] methionine-labeled ECs was not affected, and studies with cycloheximide showed that the effect of LDL and acetyl-LDL on PAI-1 release was due to de novo protein synthesis. Experiments using the C7 monoclonal antibody against the LDL receptor and binding-defective LDL indicated that the effect of LDL on the synthesis of PAI-1 was not dependent on the interaction of the LDLs with their specific receptors. Finally, extensive oxidation of LDL prevented and even reversed the effect of LDL on PAI-1 release by ECs. It is concluded that LDL specifically increases the synthesis of PAI-1 by ECs with mechanisms that are not receptor mediated.

Cells, Cultured↗
PubMed1993

Effect of atherogenic lipoproteins on PAI-1 synthesis by endothelial cells.

Cultured human umbilical vein endothelial cells (EC) exposed to native and acetylated low density lipoproteins (LDL and acetyl-LDL) show an increased synthesis of PAI-1. Confluent EC monolayers were incubated for 16-18 hours in medium 199 with or without different concentrations of LDL and acetyl-LDL and PAI-1 antigen levels were measured in conditioned medium. LDL and acetyl-LDL increased the release of PAI-1 by EC in a concentration-dependent manner. The effect was specific for PAI-1 because tissue type plasminogen activator (t-PA) and expression of procoagulant activity were not affected by either lipoprotein. The observation that native and acetyl-LDL, which are known to interact with different receptors on EC, exert the same stimulatory effect on PAI-1 release rules out the possibility of an involvement of the LDL receptor in mediating this effect. Experiments carried out incubating native LDL in the presence of a monoclonal antibody against LDL receptor and using binding-defective LDL with a reduced affinity for the LDL receptor (approximately 50% with respect to normal LDL) further excluded an involvement of the classical LDL receptor in mediating the effect of the lipoproteins on PAI-1 synthesis by EC.

Arteriosclerosis↗
PubMed1992

Hypertriglyceridemia and regulation of fibrinolytic activity.

A relation between elevated triglyceride (TG) levels and alterations of the fibrinolytic system has been recognized in studies of patients with coronary heart disease. In this investigation, the total fibrinolytic activity and the levels of specific components of the fibrinolytic system were evaluated in plasma samples from a highly selected group of patients with type IV hyperlipoproteinemia before and after a dietary treatment aimed at reducing TG levels. The fibrinolytic response of type IV patients was comparable to that of normolipidemic subjects, whereas tissue-type plasminogen activator antigen levels before and after venous occlusion (p less than 0.01) and resting plasminogen activator inhibitor-1 (PAI-1) antigen (p less than 0.01) and activity (p less than 0.01) were significantly higher in hypertriglyceridemic subjects compared with controls. After dietary treatment, a 22% reduction in TG levels was attained in type IV patients, with no appreciable modification of fibrinolytic parameters. The analysis of the single-patient data revealed a tendency toward normalization of PAI-1 levels only in those patients who showed a TG reduction greater than or equal to 20%. Very low density lipoproteins (VLDLs) from both normal and type IV patients concentration-dependently stimulated PAI-1 release by endothelial cells and HepG2 cells, with the effect of VLDL from type IV patients being more pronounced on HepG2 cells. The release of PAI-1 induced by VLDL in competent cells may thus account for the elevated levels of this antifibrinolytic protein that occur in hypertriglyceridemic patients.

Adult↗
PubMed1991

Frequency of multiple sclerosis in Valle d'Aosta, 1971-1985.

According to studies done before 1980, the multiple sclerosis (MS) prevalence rate in Italy ranged from 7.2 to 27.1 cases per 100,000 inhabitants. More recent work has consistently put the MS prevalence rate to over 30 cases per 100,000 inhabitants. If these recent data are confirmed in the future, Italy can no longer be regarded as a country at low risk for MS, but must be included among the medium-high risk countries of continental Europe. We report the results of a prevalence and incidence survey conducted in Valle d'Aosta, a region whose special features make it an excellent epidemiological model. The mean annual incidence was 2.1 and on December 31, 1985, the prevalence was 39 cases per 100,000 inhabitants. These results confirm that the incidence and prevalence rate of MS in Valle d'Aosta is close to that of areas at high-risk for MS.

Adolescent↗
PubMed1981

Treatment of radiolucent gallstones with CDCA or UDCA. A multicenter trial.

Patients with radiolucent gallstones (diameter less than 1.5 cm) and functioning gallbladder were treated for 6-12 months with CDCA (38 patients, 12-15 mg/kg/day) or UDCA (78 patients randomly allocated to receive 5-6 or 10-12 mg/kg/day). Complete dissolutions and partial plus complete dissolutions were respectively 26 and 58% for CDCA, 14 and 58% for UDCA at the lower dose, and 29 and 71% for UDCA at the higher dose. Statistical analysis did not show any significant difference between the three different treatments. In patients with stones of 4-10 mm diameter treated with UDCA, complete dissolution occurred at the lower dose in 0 of 14 cases while complete dissolutions occurred at the higher dose in 5 of 18 cases, suggesting that the latter dose may be more effective (0.05 less than P less than 0.1). A highly significant correlation was demonstrated between gallstone size and number of dissolutions with both doses of UDCA. No side effects were observed with UDCA, while with CDCA diarrhea occurred in 28% and a transient increase in SGOT in a single patient. 1 patient on UDCA required emergency cholecystectomy for acute cholecystitis. Dyspeptic and/or pain symptom-atology improved in 65 and 85% of the patients treated with CDCA and UDCA, respectively. No variations in the blood lipids were observed.

Adult↗
PubMed1981

Radiolucent gallstone dissolution with bedtime UDCA administration.

26 patients (20 females and 6 males, mean age 40.5 years +/- SEM 2.20, mean weight 60.2 kg +/- 1.98) with radiolucent gallstones of diameter less than or equal to 10 mm were treated for 6 months with ursodeoxycholic acid (UDCA), a single dose of 600 mg at bedtime. The rate of partial + complete dissolutions was 85%, reaching 100% for gallstones of less than 4 mm diameter. No side effects were observed. In a similar series of patients treated with UDCA t.i.d. at mealtimes (10--12 mg/kg/day) a slightly lower dissolution rate was obtained but the difference was not statistically significant.

Adult↗