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Biomedical subjects

M Belloni

Publications and source records attributed to M Belloni.

At least 37 records · Page 2Linked to original sources
PubMed1994

Antisense strategy unravels tau proteins as molecular risk factors for glutamate-induced neurodegeneration.

1. We investigated the possible involvement of tau proteins in the neurotoxic process activated by glutamate using the oligonucleotide antisense strategy. 2. We found that pretreatment of granule cells with an antisense oligonucleotide of the tau gene completely prevented the increase in tau immunoreactivity induced by glutamate. 3. A significant amount of the tau antisense oligonucleotide (about 1 to 2% of total) was taken up by the cells and remained stable in the cells for at least 60 min. A dose-response study revealed that 25 microM tau antisense oligonucleotide was the most efficacious concentration in terms of prevention of glutamate-induced tau immunoreactivity increases, without affecting basal tau expression. Higher concentrations of tau oligonucleotide antisense reduced tau immunoreactivity in control cells. 4. Significantly, the concentration-response curve of glutamate for inducing neuronal death in cells pretreated with tau antisense oligonucleotide showed a shift to the right compared to those obtained in untreated or tau sense oligonucleotide-treated cells. 5. Since inhibition of tau synthesis does not completely prevent but only decreases the neuronal sensitivity to glutamate, it is tempting to speculate that accumulation of tau within the neuron in response to glutamate represents one of the molecular risk factors lowering the safety margin of neurons to excitotoxic-induced injury.

Animals↗
PubMed1993

Deafferentation induces early and delayed differential changes in the pattern of expression of the various guanine nucleotide binding protein mRNAs in rat striatum.

A polymerase chain reaction-derived method was used to identify and quantitate the relative abundance of the different mRNAs encoding various isoforms of the guanine nucleotide regulatory protein Gs, Gi, and Go alpha subunits in the striata of rats unilaterally injected with 6-hydroxydopamine in the substantia nigra. Thirty days after the lesion, the mRNA levels of the G(o) and of the Gi 1 alpha subunits were increased by about 2-3 times, those of the Gi 3 decreased by about 60% and those of Gi 2 and Gs unmodified. The pattern of expression of the G(o) alpha subunits mRNA changed in a time-dependent fashion, being significant 20 days after the lesion. The decrease in Gi 3 alpha subunit mRNA levels was maximum 10 days after the lesion and tended to be reduced in magnitude with time while the changes in Gi 1 alpha subunit mRNA showed a byphasic behaviour being reduced at 10 days and increased at 30 days after the lesion. These data suggest that the expression of the various G protein alpha subunits in the striatum are continuously regulated by factors originating from afferent neurons and surrounding cells.

Animals↗
PubMed1993

Complications of plasma-exchange.

Complications in apheresis affect on the average 40% of treated patients and 10-14% of the procedures. The mortality rate is 1/500 treated patients. The utilization of more complex techniques, central catheters, plasma infusion and even more the superimposition of different factors increase the incidence and gravity of side effects. Very influent are also the underlying pathologies and the clinical conditions; particularly at risk are patients with TTP/HUS and GBS. However, PE represents a relatively safe therapy in which prevention of complications requires a particularly diligent personnel and a careful evaluation of indications.

Blood Component Removal↗
PubMed1993

Apheresis and biocompatibility: complement activation.

When blood comes into contact with plastic surfaces of extracorporeal circuits activation of different biological systems occurs, among them the complement. This will be activated mainly through the alternative pathway but also through the classical one. The activation through the latter pathway occurs when antibodies directed against polymeric materials used for the production of extracorporeal circuits or substances utilized for their sterilization are produced by the patient's immunosystem. Even if complement activation occurs almost constantly during apheretic procedures the natural inhibitory mechanisms of this system attenuate and disguise this phenomenon. Important and clinical manifestations occur in particular patients or in case of technologically more complex techniques. In apheresis the complement activation may be implicated in the relatively frequent complications such as fever and chills, hypotension, as well as in the rare but severe cases of ARDS.

Biocompatible Materials↗
PubMed1993

[Retroextraperitoneal laparoscopic nephrectomy].

The authors describe a new technique of laparoscopic nephrectomy; the retroextraperitoneal approach has been successfully performed in 4 patients with the following indications: 2 non functioning hydronephrotic kidneys, 2 atrophic chronic pyelonephritic kidneys. The patient was put in a proneoblique position after the retrograde placement of a ureteral catheter up to the renal pelvis, through which the contrast medium was injected. The Veress needle is inserted under fluoroscopic guidance into the perirenal fatty space which was insufflated with CO2. One 12 mm and three 10 mm Trocars were inserted into the cavity created by gas in the trapezoid area whose boundaries are: the 12th rib, the iliac crest, the posterior axillary line and the sacrospinalis muscle. The kidney was progressively dissected free with the traditional laparoscopic instruments (forceps and scissors). The artery has always been closed with clips. In two patients the vein has been stapled and cut with EndoGIA. After the section of the clipped ureter the kidney was removed en block by pulling it out through the 20 mm Kleiber Trocar in two cases and in the other two cases by extending to a length of 4 cm the port of one Trocar. The average total operating time was 4.35 hours and blood loss < 200 cc. The patients were all discharged on the fourth postoperative day. The advantages of the retroextraperitoneal approach with respect to open surgery are synthetically the following: a less traumatic and a more accurate dissection almost always bloodless; a shorter hospitalization period; an almost painless postoperative course.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Ligation of the internal spermatic vein through 2 laparoscopic ports].

Thirty-three two port laparoscopic internal spermatic vein ligations have been performed in 31 patients in our Department. The procedure carried out through two 10 mm ports in a mean time of 25 minutes decreases both the invasivity of intervention and the costs when reusable instruments are used. The technique is feasible with an operative laparoscope (working channel diameter 4 mm) through which a grasp can be maneuvered. The two port procedure is as safe as the three port procedures. Preliminary follow up indicated only one recurrence of varicocele (4%). Out of the 19 patients treated for male subfertility who have at least a 6 month follow up, eleven reported an improvement in seminal quality. All the patients but one were discharged on the first postoperative day. Laparoscopic internal spermatic vein ligation provides a real alternative to different surgical techniques decreasing postoperative pain and shortening period of convalescence with immediate return to full activity. The advantages of laparoscopic internal spermatic vein ligation are increased with the two port procedure.

Adolescent↗
PubMed1992

Identification of propafenone metaboliser phenotype from plasma and urine excretion data.

The aim of the study was to validate a test based on analyses of urine to identify the propafenone metaboliser phenotype during routine chronic therapy. Twenty seven patients chronically treated with propafenone were studied. A debrisoquine test was performed in 10. Propafenone and its metabolites in plasma and urine were measured by HPLC. Propafenone, 5-hydroxypropafenone and N-depropylpropafenone concentrations in plasma were 1.09, 0.182 and 0.101 ng.ml-1, respectively. Total recovery of the administered dose in urine was 30.7%. Two patients were identified as PM, based on the result of the debrisoquine test (log D/4OHD of 1.26 and 1.36). This finding was confirmed by the propafenone metabolic ratio in urine, but the plasma data did not permit clearcut separation of the phenotypes. Propafenone/5-hydroxypropafenone in plasma was not a good predictor of metabolizer phenotype. Although the number of patients who completed all three tests was limited, it is concluded that analysis of propafenone/5-hydroxypropafenone in urine collected between two consecutive doses at steady-state is more practical than the debrisoquine test and more specific than determining the propafenone/5-hydroxypropafenone ratio in plasma, for identification of the propafenone metaboliser phenotypes.

Adolescent↗
PubMed1992

Activation of dopamine D2 receptors linked to voltage-sensitive potassium channels reduces forskolin-induced cyclic AMP formation in rat pituitary cells.

3,4-Dihydroxyphenylethylamine (dopamine) D2 receptor agonists, including BHT 920 and bromocriptine, and the potassium channel opener minoxidil share the property of hyperpolarizing the plasma membrane by activating voltage-dependent potassium channels. These drugs were tested for their ability to inhibit the cyclic AMP formation induced by forskolin either in intact or in broken pituitary cells. In contrast to bromocriptine, which was active in both experimental systems, BHT 920 and minoxidil inhibited the forskolin-induced cyclic AMP formation in intact-cell but not in broken-cell preparations. The effects of BHT 920 were (a) concentration dependent, with a calculated IC50 of 0.7 microM, (b) dopaminergic in nature, being specifically antagonized by sulpiride, (c) not additive with those induced by minoxidil, and (d) less effective in the presence of potassium channel blockers, such as 4-aminopyridine and tetraethylammonium. These data indicate that the inhibition of forskolin-induced cyclic AMP formation by BHT 920 in intact pituitary cells is not a primary consequence of receptor occupation, but a late event, possibly related to the opening of voltage-dependent potassium channels elicited by this drug through the activation of a subtype of dopamine D2 receptors uncoupled to adenylyl cyclase.

Adrenergic alpha-Agonists↗
PubMed1992

Immunization and vaccination protocol in hemodialysis patients with naturally acquired hepatitis B antibody.

Long-term behavior of naturally acquired anti-HBs antibody was tested every 6 months for 3 years in 22 dialysis patients. Fifteen of them maintained protective levels throughout follow-up (102 and 85.5 mUI/ml at the beginning and the end, respectively). Seven of them became anti-HBs and were submitted to a 40-micrograms booster injection of hepatitis B vaccine. Seroconversion was observed in 6 of 7 patients (85.7%) with a mean anti-HBs titer of 90.4 and 47.3 mUI/ml after 3 and 6 months, respectively. Protective anti-HBs level may be maintained longer in patients with natural immunity than in HBsAg-negative vaccinated subjects. Effectiveness of a reduced vaccination protocol in patients who have lost their natural immunization should be confirmed with further studies.

Adult↗
PubMed1985

Effect of lymphocytapheresis plus cyclophosphamide on the course of a chronic progressive form of multiple sclerosis.

We report a case of a 16 year old boy with a chronic progressive form of Multiple Sclerosis treated with lymphocytapheresis and a low dose regimen of cyclophosphamide. A progressive improvement in the disability index and slowing of the clinical course were obtained. No side effects were observed. Depletion of lymphocytes and their pharmacological suppression point to their possible role in the induction of an immunoregulation of the disease process.

Adolescent↗
PubMed1985

Effect of heparin and aspirin on platelet and clotting activation during leukapheresis.

Beta-thromboglobulin (beta TG), serotonin (5HT) and fibrinopeptide A (FPA) were assessed in twenty-two normal donors before, during, and at the end of leukapheresis. Seven procedures were carried out adding heparin to the circuit, and seven adding acetyl salicylic acid (ASA). The remaining eight procedures were carried out using only citrate and served as controls. Plasma beta TG increased both during and after the apheresis, together with a significant decrease of the intra-platelet content. Platelet 5HT did not show significant changes whereas FPA increased significantly. Using heparin, we obtained a complete prevention of FPA cleavage during the entire procedure, while beta TG increased at the middle of the procedure. No significant effects were observed using ASA both on beta TG and FPA levels. These features clearly indicate the activation of platelets and the thrombin generation in the apheresis circuit. Nevertheless, the activation of the clotting system seems to be predominant, as supported by the improved effect of heparin on beta TG and FPA amounts.

Adult↗
PubMed1983

[Blood hyperviscosity syndromes].

Hyperviscosity syndromes are characterized by altered blood flow properties; the rheological properties of blood depend from cellular or plasmatic factors. In this study we have evaluated the role of some high molecular weight proteins (IgG, IgA, IgM, fibrinogen) and of some triglyceride-rich lipoprotein fractions. In Waldenström's disease a significant increase of apparent blood viscosity and plasma viscosity was observed; erythrocyte filterability was reduced. In patients with IgG and IgA myeloma just a slight increase of viscosity was observed. As for lipoprotein role, patients with hypertriglyceridemia type IV and V of Fredrickson have shown a significant increase of plasma viscosity; in these hyperlipidemias triglyceride levels were significantly correlated with both apparent blood viscosity and plasma viscosity. No correlation was observed with erythrocyte filterability. These data suggest that serum proteins and high levels of triglycerides can modify blood rheological properties with both increased viscosity and reduced erythrocyte filterability.

Blood Pressure↗
PubMed1981

Improvement of platelet aggregation abnormalities in thrombocytosis after thrombocytopheresis.

Platelet function tests were performed in three patients with thrombocytosis in myeloproliferative disorders before and after a swift reduction of platelet count by thrombopheresis. The decrease of platelet count obtained after the procedure was reversed in six days. In two patients with platelet aggregation defects, the normalization of aggregation abnormalities was observed after pheresis, followed by a progressive decrease of platelet response until the pre-pheresis values on 6th day. In the third patient with normal platelet aggregation, a progressive increase of platelet aggregation response was noted on the days following thrombopheresis with ischaemic symptoms of a foot toe. In all three patients, the changes of platelet aggregation were accompanied by a related increase of megathrombocytes. In the two patients with platelet aggregation abnormalities, plasma and platelet beta-thromboglobulin levels were related to changes in platelet count and aggregation.

Adult↗
PubMedDate not supplied

Dopamine D2, D3, and D4 receptor mRNA levels in rat brain and pituitary during aging.

Reverse Transcriptase-Polymerase Chain Reaction technique was used to determine the levels of the mRNAs encoding different receptors belonging to the D2 family in various brain areas of 6-, 12-, 18-, and 24-month-old rats. We found a progressive, age-dependent reduction in the mRNA levels of D2 short and D2 long receptors in corpus striatum, substantia nigra, and frontal cortex. D2 short and D2 long receptor mRNA levels were unchanged in hippocampus and olfactory tubercle, while they increased in pituitary. D3 receptor mRNA levels were reduced in olfactory tubercle and unchanged in striatum. D4 receptor mRNA levels were unmodified in pituitary gland. These data suggest that the molecular mechanisms responsible for regulating the pattern of expression of the various dopamine receptors are differentially regulated by aging.

Aging↗