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Biomedical subjects

M Marconi

Publications and source records attributed to M Marconi.

At least 55 records · Page 3Linked to original sources
PubMed1995

Antibody response to pneumococcal vaccine in children receiving bone marrow transplantation.

Fifty-three pediatric patients given an allogeneic or an autologous bone marrow transplantation (BMT) were immunized with a polyvalent pneumococcal capsular polysaccharide vaccine (Pneumovax II). Vaccine was administered six months or more after BMT and the pneumococcal IgM, total IgG, and IgG subclasses levels were evaluated before and three weeks after immunization. Immunization promoted a significant rise in antibody serum levels (P < 0.000001), and all children vaccinated more than two years after transplantation responded to pneumococcal polysaccharides, whereas only 20-30% and 50% of patients given BMT between six months and one year and one and two years, respectively, mounted an effective antibody production (P < 0.0001). In univariate analysis, lapse of time from BMT to vaccination, chronic graft-versus-host disease occurrence, and female sex influenced the response rate. However, in multivariate analysis, only time between marrow transplant and immunization was a powerful predictor of response. Interestingly, four of 11 patients with IgG2 deficiency before immunization normalized serum levels of this IgG subclass after the pneumococcal antigenic challenge. Our study suggests that time after transplant is the major factor influencing the recovery of immune reactivity to polysaccharide antigens. This seems to confirm the hypothesis that ontogeny of the B-cell repertoire follows a predetermined sequential program in which polysaccharide antigens are some of the last to evoke an antibody response.

Adolescent↗
PubMed1995

Cardiologic abnormalities in patients with long-term lupus nephritis.

To assess the cardiological status of patients with long-term lupus nephritis we evaluated 30 patients (mean age 43 +/- 11 years) with lupus nephritis lasting from at least 10 years (mean 15 +/- 5 years). At the time of cardiological evaluation the mean plasma creatinine was 132.6 +/- 11.1 mumol/l and in 28 patients lupus had been quiescent for at least 3 years. Fourteen patients (46.6%) showed one or more cardiac abnormalities: 10 had valvular lesions (1 verrucous endocarditis, 9 thickening and stiffness of one or more valves)--4 patients had regional myocardial akinesis as a consequence of a previous cardiac infarct (one had valvular abnormalities too). One patient had pulmonary hypertension probably secondary to pulmonary vasculitis. No patient had pericarditis. These cardiac abnormalities proved to be statistically correlated with the number of ARA criteria (p = 0.045), the number of lupus flares (p = 0.004), the serum levels of cholesterol (p = 0.04) and of triglycerides (p = 0.025) as well as the duration of hypercholesterolemia (p = 0.005) and of hypertriglyceridemia (p = 0.007). In conclusion, in patients with long-term lupus nephritis cardiac lesions are frequent. The main lesions are non-verrucous valvulopathy (probably a consequence of healing verrucous endocarditis) and cardiac infarct (caused by an accelerated atherosclerosis). On the contrary cardiac lesions caused by active lupus as pericarditis, myocarditis and verrucous endocarditis are rare.

Adult↗
PubMed1995

[Elective electric cardioversion of atrial fibrillation in adults with underlying heart disease: a proposal of optimizing the procedure].

BACKGROUND: Synchronized direct current cardioversion (DC) is widely used for atrial fibrillation (AF) conversion to sinus rhythm. With the purpose to identificate the optimal procedure for the effective DC of AF, we compared the results obtained following traditional free-multiple shock sequence to simple two-shock sequence in two groups of adults with underlying heart disease submitted to elective DC for AF in our Dept. of Cardiology. METHODS: The first group, retrospectively considered, included 84 episodes of AF occurred in 79 patients. DC started on an energy level of 100 joules (J) and, when unsuccessful, repeated on increasing levels, from 150J to 360J, depending on physician preference. An additional shock of 360J was always delivered when the last shock-dose proved to be ineffective. The second group, prospectively considered, included 61 episodes of AF occurred in 61 patients. The protocol provided for an initial shock of 200J followed, when necessary, by a second one of 360J and no additional shocks. RESULTS: Conversion rate (86.9% vs. 85.2%) showed no statistical difference (p = NS) between groups. Following the two-shock protocol, a significant reduction of the mean amount of energy used for effective conversion (258.5J vs. 345.0J; p < 0.001), of the mean amount of total energy delivered to patients (302.9J vs. 439.6J; p < 0.001), particularly to non responders (560.0J vs. 1067.2J; p < 0.0001) was found. Using the first procedure only 13.1% of patients were cardioverted delivering 100J and 35.8% of them needed additional 200J. In the second group, the initial shock of 200J cardioverted 54.1% of patients. In both studies no patients had adverse effects either during or early after DC or during the four-week follow-up, where haemorrhagic and thromboembolic complications has been also considered. CONCLUSIONS: Two-shock protocol seems to provide better success/total energy delivered ratio, to reduce the total amount of energy delivered to each patient and to shorten the DC procedure when compared to free-multiple shock sequence usually performed, reducing the total time of anesthesia.

Adult↗
PubMed1994

Ineffective expression of CD40 ligand on cord blood T cells may contribute to poor immunoglobulin production in the newborn.

A major feature of the immature immune system in the newborn is its inability to produce significant levels of immunoglobulins other than IgM in response to antigens. It has recently been demonstrated that interaction of the CD40 molecule on B cells with the CD40 ligand (CD40L) on activated T cells is pivotal for immunoglobulin switching. In view of these findings, we have tested cord blood mononuclear cells (CBMC) for expression of CD40L. Our data clearly demonstrate that freshly isolated CBMC do not express significant levels of CD40L upon in vitro activation; this defect is intrinsic to CD4+ cord blood lymphocytes. In vitro priming of CBMC with phytohemagglutinin and interleukin-2 for several days induced a conversion from the "naive" to the "memory" phenotype (as assessed by expression of CD45 isoforms) and led to substantial CD40L expression upon appropriate restimulation. These data indicate that ineffective CD40L expression might represent a major factor for reduced immunoglobulin production in the neonate, and suggest that antigenic exposure in vivo leads to changes in the genetic program, enabling T cells to express CD40L.

Adult↗
PubMed1994

Influence of contrast enhancement and pseudocolor transformation on the diagnosis with digital subtraction images (DSI).

This study evaluated the influence of the image processing step of digital subtraction images on inter- and intraexaminer agreement in the interpretation of alveolar bone changes. 52 pairs of standardized radiographs from various clinical trials were included. Six dentists were invited to interpret the images projected as slides in random order. Display one demonstrated the slide of the digitized baseline radiograph and the follow-up image. Display two showed the regular digital subtraction image. Display three represented a grey level contrast enhanced version and displays four and five were pseudo/color enhanced subtraction images. Applying kappa-statistics and multiple regression analysis it was demonstrated that better agreements were obtained when the two color coded displays of subtraction images were shown to the interpreters. The image interpretation was performed in two series. For the first evaluation the interpreters were not informed about the therapy provided nor the time elapsed between taking the pairs of standardized radiographs. In the second series this information was provided. It could be demonstrated that the agreement in the diagnosis of bone change was less influenced by the knowledge about the clinical information if the two color-converted versions of subtracted images were evaluated. Thus, it was concluded that image processing of subtraction images using color enhancement might improve agreement in the diagnostic task. The color coded images were less influenced by the bias in the interpretation of an expected change. The decision making process might be more objective when using color enhanced subtraction images.

Alveolar Bone Loss↗
PubMed1994

Alcohol consumption among high school students and young athletes in north Italy.

Alcohol consumption was assessed among 366 male high school students and 330 young men playing in sports teams. On the average, the athletes drank less wine, beer and spirits than the students and reported fewer drunkenness episodes. The association of alcohol drinking with sporting activity and with some independent variables was estimated by logistic regression techniques, fitting models for ordinal or nominal response variables. Point estimates of the odds ratios and their confidence limits showed: 1) an inverse relationship between alcohol drinking and sporting activity, especially as regards the consumption of spirits; 2) a strong positive relationship of alcohol drinking with both experimental and regular smoking; 3) peer alcohol drinking (best friend's and girlfriend's drinking) was the strongest predictor of the participant's alcohol consumption.

Adolescent↗
PubMed1993

Platelet concentrates from buffy coats: improved conditions for preparation and evaluation in routine clinical use.

Since 1990, platelet concentrates prepared by soft centrifugation of buffy-coat pools diluted with a glucose-free, commercially available crystalloid solution (BC-PC) are the first choice product for all platelet recipients in our institution. Numerous in vitro and in vivo observations from our own and other laboratories indicate that BC-PC compare favorably to PC prepared from platelet-rich plasma (PRP). In the present in vitro study we evaluated traditional and bottom-and-top bags and modified centrifugation conditions with the aim of increasing in vitro platelet yield in BC-PC. This was 14-18% higher compared with our previous protocol when prolonged centrifugation and bottom-and-top bags were used. In addition, we evaluated post-transfusion platelet count increments in 42 unselected adult hematological patients routinely transfused with 703 1-5 day-old BC-PC pools. Transfusion data were managed with PLATELET, an MS-DOS compatible program which includes automated calculation of transfusion efficacy and periodic patient reports. Mean pre-, 1 h and 24 h post-transfusion platelet counts were 16, 38 and 28x10 9/L, respectively. Mean 1 h and 24 h post-transfusion platelet count increments, expressed as percentage of expected, were 40 and 24%, respectively. These data were similar to those obtained previously in 189 unselected hematological patients given 2432 PRP-PC transfusions (mean 1 h post-transfusion increment 46% of expected). The present in vitro study confirms that similar platelet yields can be obtained with the BC and PRP methods. In vivo findings show that also in routine conditions post-transfusion increments of PRP-PC and BC-PC are similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Single-donor platelet concentrates stored in synthetic medium. In vitro and in vivo studies.

Single-donor platelet concentrates (PC) were prepared in 80-120 ml plasma and stored in two polyolefin bags after addition of 250 ml plasmalyte, a simple, glucose-free synthetic medium that was previously used for platelet storage; when compared to PC stored in plasma, PC stored in plasmalyte, showed similar platelet quality, morphology and function after 5 days of storage. In vivo increments observed after transfusion of PC stored for 5 days in plasmalyte were similar to those observed after transfusion of 1-2 day old PC stored in plasma. Moreover, transfusion of 5-day old PC stored in plasmalyte was associated with correction of prolonged bleeding times in all 3 of the 3 patients evaluated. It is concluded that plasmalyte seems to be promising as a medium for single-donor PC storage.

Blood Donors↗
PubMed1993

[Non-invasive conversion of atrial flutter using an implanted double-chamber pacemaker].

The increasing sophistication of implantable pacemakers for treating both tachycardia and bradycardia has resulted in the ability to use the implanted device for more interventions other than simple pacing. The interruption of tachyarrhythmias has been attempted using special programmers which allow stimulation at different cycle lengths, even very short ones. We describe two cases in which neither antitachycardia device nor special equipment were used to terminate an atrial flutter. Two patients with Sick Sinus syndrome who had received DDD pacemaker, presented with a sustained atrial flutter. Pacers were set in AOO mode at the highest rate programmable (119 and 130 ppm, respectively) obtaining an underdrive atrial pacing (F-F rate was 280 ppm in both cases) which was able to convert the atrial flutter to sinus rhythm. The procedure was performed in the outpatient clinic. Our cases illustrate one of many potential applications of permanent pacemakers in noninvasive settings. We can conclude that when atrial flutter occurs in AAI or DDD pacemaker recipients, underdrive atrial pacing using the implanted pacemaker should always be attempted.

Aged↗
PubMed1992

CYP21/C4 gene organisation in Italian 21-hydroxylase deficiency families.

A total of 33 Italian 21-hydroxylase (21-OH) deficiency families were investigated using a combination of short and long range restriction mapping of the CYP21/C4 gene cluster. The analyses revealed that large-scale length polymorphism in this gene cluster strictly conformed to a compound variable number of tandem repeats (VNTR) plus insertion system with between one and four CYP21 + C4 units and seven BssHII restriction fragment length polymorphisms (RFLPs) (75 kb, 80 kb, 105 kb, 110 kb, 135 kb, 140 kb and 180 kb). A total of 9/66 disease haplotypes, but only 1/61 non-disease haplotypes, showed evidence of gene addition by exhibiting three or more CYP21 + C4 repeat units. Of these, two were identified in one 21-OH deficiency patient who has a total of eight CYP21 + C4 units, being homozygous for the HLA haplotype DR2 DQ2 B5 A28. This haplotype carries four CYP21 + C4 units, three of which contain CYP21A-like genes and one of which contains a CYP21B-like gene that presumably carries a pathological point mutation. Of the other gene addition haplotypes associated with 21-OH deficiency, four show three CYP21 + C4 units flanked by HLA-DR1 and HLA-B14 markers. Although such haplotypes have commonly been associated with non-classical 21-OH deficiency, three examples in the present study are unexpectedly found in two salt-wasting patients, who are respectively homozygous or heterozygous for this haplotype. Only 7/66 disease haplotypes showed evidence of a CYP21B gene deletion.

Adrenal Hyperplasia, Congenital↗
PubMed1992

VDD single pass lead pacing: sustained pacemaker mediated tachycardias unrelated to retrograde atrial activation.

Pacemaker mediated tachycardias (PMTs) are a well known complication of P synchronous pacing. Although the initiating mechanisms are several, all of them are associated with retrograde atrial activation, which is sensed by the atrial sensing channel, resulting in ventricular pacing. In 19 patients suffering from symptomatic AV conduction disturbances and normal sinus node function, a VDD pacing system connected to a single pass ventricular lead with dual chamber electrodes was implanted. The bipolar atrial electrode, floating in the right atrium, was used to detect endocardial atrial electrograms that were differentially processed within the pacemaker for optimal discrimination and filtering of undesirable signals. The widely programmable atrial sensitivity (amplitude and filtering) allowed stable P synchronized ventricular pacing in all patients, but in five of them, sustained PMTs not related to retrograde atrial activation was documented during the follow-up. The common mechanism for the onset and maintenance of these PMTs was traced to the abnormal sensing of the terminal forces of ventricular activation and/or of the T wave. The possibility of interferences between ventricular and atrial electrodes (crosstalk) was also considered. The reduction of atrial channel sensitivity represented in all cases the only effective procedure to prevent this type of PMT. In conclusion, the bet signal to noise ratio is an important endpoint to assure the proper function of a single lead VDD pacing system. Furthermore, using the differential amplifier built within the pacemaker, consideration should be given to the optimal mode of rejection of the terminal forces of the QRS and T wave.

Aged↗
PubMed1992

In vivo activated cord blood lymphocytes express high affinity interleukin-2 receptor: evaluation of their responsiveness to in vitro stimulation with recombinant interleukin-2.

We report the phenotypical and functional characterization of a cord blood mononuclear lymphocyte subset (CBMC) which expresses the p55 chain of interleukin-2 receptor (IL-2R, CD25). The great majority of CD25-positive CBMC are activated CD3-positive T lymphocytes in that most of them are HLA-DR-positive, coexpress both CD4 and CD8 antigens and at least a part of them display high affinity IL-2R. In keeping with the expression of both chains of IL-2R (p55 and p75), enriched CD25-positive CBMC are able to display strong IL-2-induced proliferation and lymphokine-activated killing activity. The percentage of CD25-positive cells is higher in cord blood than in adult peripheral blood and their presence could be peculiarly important in the neonatal period, when specific T-cell-mediated immune responses are still on their way to full maturation.

Cytotoxicity, Immunologic↗
PubMed1992

[Accidental ventricular fibrillation during transesophageal atrial overdrive].

Transesophageal atrial overdrive stimulation is a widely used technique for the interruption of atrial flutter and supraventricular tachyarrhythmias. We describe a case of 60 year old man with a previous myocardial infarction, suffering from angina during effort after aortocoronary bypass who presented several episodes of atrial flutter treated with success by transesophageal atrial overdrive stimulation using swallowing electrodes. During the treatment of the last episode of atrial flutter, after a 5 s burst at 300 b/min ventricular fibrillation occurred and was promptly interrupted by DC shock. This is the first case in our experience and probably the first report of ventricular fibrillation induced by swallowing electrodes. Possible mechanisms as pharmacological interactions, accidental ventricular stimulation, etc, are discussed. In conclusion, even though the risk of dangerous arrhythmias is very low, transesophageal atrial overdrive stimulation should be performed by experts in an equipped room.

Angina Pectoris↗
PubMed1992

Invasive and echocardiographic evaluation of non-Q myocardial infarction with isolated stenosis of descending anterior coronary artery.

Prognostic and clinical characteristics of acute myocardial infarction (AMI) can usually justify surgical and/or angioplastic approach if the residual ventricular function is still good. Multivessel disease frequently complicates results interpretation. We studied with 2D echocardiography and coronary angiography two groups of patients with one vessel stenosis located on anterior descending (AD) and previous AMI (means 19 days): 23 patients with spontaneous non-Q infarction (group 1), and 23 patients with Q infarction. Left ventricular function was better in group 1. Percent occlusion of AD was lower in group 1 and angiographic AD caliber was significantly higher. Differences between groups were much more evident in subgroups with proximal stenosis of AD: patients of non-Q subgroups had very good left ventricular function but frequently had post-AMI instable angina (88%). Our results underline the usefulness of aggressive diagnostic and therapeutic approach in non-Q AMI, because of higher amount of myocardium at risk.

Adult↗
PubMed1992

Noninvasive evaluation of asymptomatic athletes with cardiac murmur.

The increasing number of amateur sportsmen enhances the need for a correct evaluation of subjects suspected of overt and mild cardiac disease. Out of 4000 athletes, 72 subjects were clinically preselected by the sport doctor during an annual routine examination. They were studied with mono and 2D echo, pulsed color (PW) and continuous wave Doppler. Five asymptomatic patients are reported with congenital or acquired valvular diseases.

Adolescent↗
PubMed1991

Analysis of X-chromosome inactivation and presumptive expression of the Wiskott-Aldrich syndrome (WAS) gene in hematopoietic cell lineages of a thrombocytopenic carrier female of WAS.

We report on a thrombocytopenic female belonging to a pedigree with the Wiskott-Aldrich syndrome (WAS). Restriction fragment length polymorphism (RFLP) analysis with probe M27 beta, closely linked to the WAS gene, demonstrated that she is a carrier of WAS. Both small-sized and normal-sized platelets were present, suggesting that, unlike the vast majority of WAS carriers, she does not manifest nonrandom X-chromosome inactivation in the thrombopoietic cell lineage. Study of X-chromosome inactivation by means of RFLP and methylation analysis demonstrated that the pattern of X-chromosome inactivation was nonrandom in T lymphocytes, but random in granulocytes. While this is the first complete report on the occurrence of thrombocytopenia in a carrier female of WAS as the result of atypical lyonization, it also suggests that expression of the WAS gene occurs at (or extends up to) a later stage than the multipotent stem cell along the hematopoietic differentiation pathway.

Dosage Compensation, Genetic↗