Injectable carbon nanotube-functionalized hydrogel as a tool for cardiac tissue engineering

Background/Introduction

Heart failure (HF) is an expensive major public health problem in the United States and around the world (1). The current treatments for HF are aimed at reducing symptoms, slowing disease progression, and reducing mortality and not aimed at repairing heart muscle or restoring function. Furthermore, even with these treatments, approximately half of patients with HF will die within 5 years of diagnosis (2). Cardiac transplantation remains the only definitive treatment for those affected with end-stage HF, but availability of donor hearts remains a major limitation (3).

Purpose

The ability of the adult heart to regenerate cardiomyocytes (CMs) lost after injury is limited, generating interest in developing tissue engineering therapies to avoid progression towards HF. Rigid carbon nanotubes (CNTs) scaffolds have been used to improve CMs viability, proliferation, and maturation (4), but require undesirable invasive surgeries for implantation. To overcome this limitation, we engineered an injectable reverse thermal gel (RTG) functionalized with CNTs (RTG-CNT) that transitions from a liquid-solution to a gel-based matrix shortly after reaching body temperature allowing for a liquid-based delivery rapidly followed by a stable-gel localization (5).

Methods and results

Here we show experimental evidences the RTG-CNT hydrogel, used as a three-dimensional (3D) niche to culture human induced pluripotent stem cells (hiPSC)-CMs, promotes hiPSC-CMs alignment and elongation with increased Cx43 localization and improved contraction function when compared with traditional two-dimensional (2D) fibronectin controls and plain 3D RTG system without CNTs. Moreover, the short-term (4-week) biocompatibility of the RTG-CNT hydrogel was also assessed in a mouse model (intracardial injection). The results confirmed that the RTG-CNT hydrogel is well tolerated by the cardiac tissue.

Conclusion

Our results indicated that the injectable RTG-CNT hydrogel has the potential to be used as a minimally invasive tool for cardiac tissue engineering efforts.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): NATIONAL HEART, LUNG, AND BLOOD (NHLBI) INSTITUTE

Mediating factors of a school-based multi-component smoking prevention intervention: the LdP cluster randomized controlled trial

The aim of this study was to investigate factors mediating the effects of Luoghi di Prevenzione (LdP) smoking prevention intervention based on social competence and social influence approaches, and characterized by peer-led school-based interventions, out-of-school workshops, school lessons, and by enforcing the school anti-smoking policy. Students aged 14-15 years in 13 secondary schools in Reggio Emilia, Italy (989 students) were randomly assigned to the LdP intervention or a control condition. The baseline and follow-up surveys were carried out before and 18 months after the intervention, respectively.The outcomes were cigarette daily and frequent smoking and smoking at school. Multilevel multiple mediation analyses were carried out in order to study effect mediation. The mediators were normative perception, positive and negative beliefs, refusal skills for smoking, social acceptability perception, risk perception, smoking knowledge and awareness about dangers of second-hand smoking.The intervention effects were explained by the social influence component through the mediator refusal skills for smoking. The programme also showed to significantly increase risk perception and smoking knowledge, even though these mediators had no effect on smoking. Moreover, LdP intervention directly reduced smoking in school areas. Future interventions should maintain and strengthen the LdP social influence component and the part regarding the school anti-smoking policy.

Incidence and prevalence of systemic lupus erythematosus in a district of North Italy

The objective of this study was to investigate the incidence and the prevalence of systemic lupus erythematosus (SLE) in an area of northeast Italy. We retrospectively examined all patients of 16 years and older of native Italian origin and resident in Ferrara district either admitted to hospital or referred to our outpatient clinic with a diagnosis of SLE determined between 1 January 1996 and 31 December 2002. SLE subjects were identified both by a search of hospital discharge code 710.0 according to the international classification of diseases-9 codes, and using a computerized search for this pathology code in the national health care system. Incidence and prevalence rates were calculated as number of cases per 100 000 inhabitants. Population data were based on the 2002 National Census. A total of 299 cases of SLE were identified. After a review of all cases by one experienced investigator, 98 were excluded because did not satisfied the 1982 revised criteria of the American College Rheumatology. Therefore, 201 patients had a definite diagnosis of SLE. The prevalence of SLE in the district was 57.9/100 000. The mean age at diagnosis was 41 years, the average duration of the disease from symptoms onset to diagnosis was 4.8 years and the female/male ratio 9: 1. Annual incidence in 2000 was 2.01/100 000, in 2001 1.15/100 000 and in 2002 2.6/100 000. This is the first study dealing with prevalence and incidence of SLE in an Italian district. Data obtained concerning prevalence, incidence, age at diagnoses and female predominance are in agreement with those published in literature.

How new imaging techniques can aid in defining the cardiovascular profile of the high-risk patient

Cardiovascular prevention has been developed in the last eight years producing an ever increasing amount of data requiring frequent updating. Studies using angiography to determine change in coronary obstruction have indicated progression, stabilization, or regression of coronary lesions associated with changes in plasma lipids and lipoproteins. Moreover, the guidelines on arterial hypertension published in 2007 listed the risk factors affecting prognosis but even by 2009 an update modified not only the list of risks, but even the philosophy behind the thought process which introduced as essential element in the prognosis of hypertension the ascertained existence of a damaged organ. Thus, the documentation of atherosclerotic vascular disease (plaques) and the quantification of its extension in the arterial tree became a determinant in the definition of cardiovascular risk. Magnetic Resonance (MRI) and coronary computed tomography (coro CT) applied to the heart and large vessels are the most promising methods.

Methylenetetrahydrofolate reductase gene promoter hypermethylation in semen samples of infertile couples correlates with recurrent spontaneous abortion

STUDY QUESTION

Is the methylation status of the methylenetetrahydrofolate reductase (MTHFR) promoter region in semen samples associated with 'recurrent spontaneous abortion' (RSA)?

SUMMARY ANSWER

MTHFR promoter hypermethylation is more frequent in semen samples from RSA couples than in semen samples from infertile couples with no history of RSA (NRSA) and affects the whole sperm population significantly more often.

WHAT IS KNOWN ALREADY

Modifications to the MTHFR gene such as polymorphisms and promoter methylations are associated with male infertility.

STUDY DESIGN, SIZE AND DURATION

Retrospective cohort study of semen samples from 20 RSA couples, 147 NRSA couples and 20 fertile men between 2011 and 2012.

MATERIALS, SETTING AND METHODS

DNA from the semen samples of RSA, NRSA and fertile men were analyzed by methylation-specific PCR amplification using primers which anneal to the methylated or unmethylated cytosine-phosphodiester bond guanine (CpG) islands within the promoter region of MTHFR. The specificity of the PCR products was assessed by DNA sequencing.

MAIN RESULTS AND THE ROLE OF CHANCE

The methylated MTHFR epigenotype (including samples where it co-existed with unmethylated MTHFR epigenotypes) was detected in 75% of RSA men, 54% of NRSA men and 15% of fertile men. MTHFR methylation was observed in the whole sperm population in semen samples from 55% of RSA men compared with 8% in NRSA men (P < 0.05) and 0% in fertile men (P < 0.05). DNA sequencing analysis was fully concordant with the PCR results and revealed that when MTHFR methylation occurred, CpG islands within the promoter region were 100% methylated (hypermethylation of MTHFR promoter).

LIMITATIONS, REASONS FOR CAUTION

The relatively small sample size of RSA infertile couples.

WIDER IMPLICATIONS OF THE FINDINGS

The hypermethylation of the MTHFR gene promoter should be taken into consideration as a novel putative risk factor in RSA etiology.

STUDY FUNDING/COMPETING INTEREST(S)

Our institution has received an FAR research grant from the University of Ferrara, Ferrara, Italy. No competing interests declared.

Bt-toxin uptake by the non-target herbivore, Myzus persicae (Hemiptera: Aphididae), feeding on transgenic oilseed rape in laboratory conditions

The potential non-target effects of genetically modified crops are some of the more debated topics within applied biotechnologies in agriculture and environmental risk assessment. The objective of the present research was to study the potential Bt-toxin uptake by the non-target herbivore Myzus persicae Sulzer (Hemiptera: Aphididae) feeding on transgenic oilseed rape plants (Brassica napus cv. 'Westar' lines GT 2-4) expressing the Cry1Ac endotoxin. A specific aim was to replicate our previous experiment in controlled laboratory conditions to avoid or minimize the risk of contamination leading to potential false positive results. The toxin levels in vernalized (V) and not-vernalized (not-V) transgenic oilseed rape plants was also monitored to better clarify the role of physiological processes on Bt-toxin expression. Cry1Ac expression in not-V plants (mean concentration±SE=167.8±5.7 μg kg-1 FW) showed a pattern of large variability, in comparison with V plants whose expression (mean concentration±SE=227.7±1.9 μg kg-1 FW) was significantly more stable. Cry1Ac toxin was detected in three aphid samples reared on V plants with a mean toxin concentration±SE of 4.8±0.6 μg Kg-1 FW and in three out of six samples of aphids reared on not-V plants (mean toxin concentration±SE=7.1±1.2 μg kg-1 FW). The mean Bt-toxin concentration of all the positive aphid samples was 5.9±1.0 μg kg-1 FW. Our results confirmed the findings of our previous experiment and highlighted the potential for Cry1Ac toxin uptake by aphids feeding on transgenic oilseed rape plants.

Dissecting the structural determinants of the interaction between the human cytomegalovirus UL18 protein and the CD85j immune receptor

UL18 is a glycoprotein encoded by the human cytomegalovirus genome and is thought to play a pivotal role during human cytomegalovirus infection, although its exact function is still a matter of debate. UL18 shares structural similarity with MHC class I and binds the receptor CD85j on immune cells. Besides UL18, CD85j binds MHC class I molecules. The binding properties of CD85j to MHC class I molecules have been thoroughly studied. Conversely, very little information is available on the CD85j/UL18 complex, namely that UL18 binds CD85j through its alpha3 domain with an affinity that is approximately 1000-fold higher than the MHC class I affinity for CD85j. Deeper knowledge of features of the UL18/CD85j complex would help to disclose the function of UL18 when it binds to CD85j. In this study we first demonstrated that the UL18alpha3 domain is not sufficient per se for binding and that beta2-microglobulin is necessary for UL18-CD85j interaction. We then dissected structural determinants of binding UL18 to CD85j. To this end, we constructed a three-dimensional model of the complex. The model was used to design mutants in selected regions of the putative interaction interface, the effects of which were measured on binding. Six regions in both the alpha2 and alpha3 domains and specific amino acids within them were identified that are potentially involved in the UL18-CD85j interaction. The higher affinity of UL18 to CD85j, compared with MHC class I, seems to be due not to additional interaction regions but to an overall better fit of the two molecules.

Automatic procedure for using models of proteins in molecular replacement

In a crystallography experiment, a crystal is irradiated with X-rays whose diffracted waves are collected and measured. The reconstruction of the structure of the molecule in the crystal requires knowledge of the phase of the diffracted waves, information that is lost in the passage from the three-dimensional structure of the molecule to its diffraction pattern. It can be recovered using experimental methods such as heavy-atom isomorphous replacement and anomalous scattering or by molecular replacement, which relies on the availability of an atomic model of the target structure. This can be the structure of the target protein itself, if a previous structure determination is available, or a computational model or, in some cases, the structure of a homologous protein. It is not straightforward to predict beforehand whether or not a computational model will work in a molecular replacement experiment, although some rules of thumb exist. The consensus is that even minor differences in the quality of the model, which are rather difficult to estimate a priori, can have a significant effect on the outcome of the procedure. We describe here a method for quickly assessing whether a protein structure can be solved by molecular replacement. The procedure consists in submitting the sequence of the target protein to a selected list of freely available structure prediction servers, cluster the resulting models, select the representative structures of each cluster and use them as search models in an automatic phasing procedure. We tested the procedure using the structure factors of newly released proteins of known structure downloaded from the Protein Data Bank as soon as they were made available. Using our automatic procedure we were able to obtain an interpretable electron density map in more than half the cases.

The management of severe vaginal obstruction from genital chronic graft-versus-host disease: diagnosis, surgical technique and follow-up

AIM

Chronic graft-versus-host disease (GVHD) is one of the most important systemic late-onset complications of haematopoietic stem cell transplantation. Gynaecological manifestations are considered relatively rare, and involve lower genital tract skin and mucosa, causing vulvar scarring, vaginal stenosis, affecting the patients' sexual life, and leading to more serious complications as haematocolpos, haematometra and abscesses. Genital GVHD can be treated with topical therapy when mild to moderate disease is present. Surgery is indicated in advanced and complicated cases to restore normal anatomy. The aim of this study is to propose a standard approach for the management of such condition when medical therapy is not effective.

METHODS

From May 2000 to January 2002, 8 patients suffering from genital chronic GVHD were operated in our institution. We describe clinical and sonographic presurgical assessment, simple or ultrasonographic guided surgical technique, postsurgical treatment and follow-up.

RESULTS

Surgery was completely successful in restoring genital anatomy in all the cases. Mean follow-up was of 17 months (6 to 38 months). Two patients early discontinued the postsurgical treatment. At 1 month complete vaginal patency was found in 6 cases, weak partial adhesions in 1 case, while 1 patient refused follow-up. Eventually, complete vaginal patency was maintained in 2 cases, and partial adhesions were found in 5 cases.

CONCLUSIONS

The combined use of clinical examination and endosonography provides a precise assessment of the level of the obstruction. The surgical technique here described is feasible and successful in restoring normal anatomy, while long term results seem related to the compliance towards the postsurgical treatment.

Novel versatile fullerene synthons

We report the synthesis of three novel, versatile fullerene intermediates whose main feature is the presence of an amino end group. Simple condensation reactions of these intermediates under standard conditions produce new derivatives that are useful for applications in materials science and medicinal chemistry.

Isolation and characterization of all eight bisadducts of fulleropyrrolidine derivatives

We report the isolation and characterization of bisadducts of fulleropyrrolidine derivatives. The compounds were characterized by means of a variety of spectroscopic techniques, including ES-MS, UV-vis, (1)H NMR, and (13)C NMR. The whole series of bisadducts was separated for the first time in the case of the bispyrrolidines, and the determination of their structure was obtained by NMR spectroscopy with the help of HMQC and HMBC techniques.

Antimycobacterial activity of ionic fullerene derivatives

Positively charged fullerene derivatives, moderately soluble in water:DMSO 9:1, have been tested using three strains of Mycobacterium spp. Some compounds inhibit the growth of Mycobacterium tuberculosis, a human clinical isolate, particularly virulent and resistant, at doses as low as 5 microg/mL.

Direct comparison of early elevations of cardiac troponin T and I in patients with clinical unstable angina

BACKGROUND

The aim of this study was to compare the prognostic efficacy of cardiac troponin T (cTnT) and I (cTnI) in patients with clinical unstable angina.

METHODS

We studied 74 patients with chest pain at rest, electrocardiographic evidence of myocardial ischemia, and normal (<6.7 ng/mL) values of creatine kinase-MB. cTnT was measured with a commercial assay (cutoff level 0.1 ng/mL) and cTnI with a preliminary research application (cutoff level 3.1 ng/mL). All patients had blood drawn at baseline and 8 hours thereafter. The prospectively defined end point was the proportion of patients identified by each assay as having myocardial damage.

RESULTS

cTnT and cTnI were elevated in the same percentage of patients (18 of 74; 24%). Overall, 23 patients had elevations of 1 or both markers. In 13 there were elevations of both. Ten patients had elevations of only one (5 for each marker). In 51 patients, no elevations were present. Death or nonfatal myocardial infarction was more frequent in patients with elevated cTnI (27.7% vs 5.3%; P =.02) than those with normal values. The prognostic influence of cTnT was less (17% vs 8.5%; P =.2). However, the difference between the 2 markers when compared directly was not statistically significant (27.7% vs 17%; P = NS).

CONCLUSIONS

These data indicate that both markers identify myocardial damage in equal numbers of patients with clinical unstable angina. Patients with elevations had a worse short-term outcome. The significance of the minor differences in prognostic value will require additional studies.

Responses of internal mammary artery graft flow to nitroprusside: a duplex Doppler study in hypertensive hearts

OBJECTIVE

To assess the response of internal mammary artery (IMA) flow of hypertensive hearts to nitroprusside infusion.

METHODS

Fifteen patients were studied with a high-frequency duplex Doppler probe from the supraclavicolar approach. All the patients had undergone coronary artery bypass surgery with an IMA graft into the left anterior descending artery. The investigated patients were normotensives (controls, n = 5) and hypertensive with a normal (group 1, n = 5) or a hypertrophic (group 2, n = 5) left ventricle. Values of the left ventricular mass index were 102 +/- 11 g/m2 in controls, 115 +/- 18 g/m2 in group 1 and 153 +/- 8 g/m2 in group 2. The IMA flow volume was studied at baseline and continuously during nitroprusside infusion. The arterial blood pressure was measured each minute by a cuff sphygmomanometer. In each patient we considered the peak flow volume (percentage increment from baseline) and the flow volume at the end point (the lowest tolerated diastolic blood pressure).

RESULTS

Nitroprusside infusion induced a comparable flow-volume increment in controls (38 +/- 27%) and in group 1 (24 +/- 11%). Conversely, the flow-volume increment was trivial in group 2 (6 +/- 6%). At the end point, the flow volume was similar to the baseline value in controls (with diastolic blood pressure 67 +/- 9 mmHg) and in group 1 (diastolic blood pressure 61 +/- 4 mmHg), whereas the flow volume declined significantly from baseline (by 23%) in group 2 at a perfusion pressure of 79 +/- 9 mmHg.

CONCLUSION

Hypertensive patients with a normal left ventricular mass exhibit a coronary flow behaviour similar to that of normotensives in response to a nitroprusside infusion. Conversely, hypertrophic hypertensives show a blunted nitroprusside-induced coronary vasodilator response and are much more vulnerable to coronary flow reductions in the face of hypotension. This dynamic assessment of flow patterns can be obtained non-invasively by duplex Doppler monitoring of IMA graft flow.

Prognostic value of a history of hypertension in 11,483 patients with acute myocardial infarction treated with thrombolysis. GISSI-2 Investigators. Gruppo Italiano per lo Studio della, Sopravvivena nell'Infarto Miocardico

OBJECTIVE

To assess the prognostic value of a history of hypertension in patients with acute myocardial infarction (AMI) treated with thrombolysis.

DESIGN

Retrospective adjusted analysis of outcome data of patients with AMI randomly allocated to treatment in a controlled study of alteplase versus streptokinase and heparin versus no heparin.

SETTING

A highly representative sample (about 90%) of Italian Coronary Care Units.

PATIENTS

Patients with (n = 3306) and without (n = 7406) a history of treated hypertension.

MAIN OUTCOME MEASURES

Morbidity and mortality during hospital stay and the next 6 months.

RESULTS

Patients with a history of hypertension had a significantly higher mortality, both in hospital and during the next 6 months. The difference persisted also after a multivariate analysis including all major prognostic factors for in-hospital and 6-month mortality, respectively. Left ventricular failure and recurrent ischaemic events (angina and re-infarction) were also significantly more frequent in hypertensives both during their hospital stay and during follow-up study.

CONCLUSIONS

A history of hypertension is a negative independent prognostic factor after acute myocardial infarction treated with thrombolysis.

Routine coronary angioplasty with autoperfusion balloon catheter: Can prolonged inflations reduce myocardial ischemia and preserve myocardial function?

Percutaneous transluminal coronary angioplasty (PTCA) is an established technique in the management of patients with angina pectoris or acute myocardial infarction. One of the major problems related to PTCA is myocardial ischemia following balloon catheter occlusion of the coronary artery. A new device utilized in an attempt to counteract myocardial ischemia is the perfusion balloon catheter which allows passive transmission of pulsatile blood flow to the distal myocardial bed. Our purpose was to compare immediate results following traditional PTCA and autoperfusion balloon PTCA in two groups randomly assigned to receive one of the two treatments (total patients n. = 158). The results show that coronary angioplasty was successfully performed in 98.87% of patients treated with autoperfusion PTCA and in 97.10% of those treated with conventional PTCA. In the autoperfusion PTCA group we observed a lower incidence (statistically significant) of ST elevation and of minor complications. We conclude that autoperfusion balloon catheter angioplasty may be recommended for its immediate success rate with good patient tolerance and lower incidence of in-hospital complications.

Non-invasive assessment of reperfusion of the infarct-related artery during coronary thrombolysis and its relation with left ventricular function

We monitored ST segment continuously for at least 3 h after the beginning of lytic treatment in 103 patients undergoing early coronary thrombolysis for acute myocardial infarction in order to ascertain whether this technique, which has been shown to be useful to assess recanalization of the infarct-related artery, is also able to identify the improvement in left ventricular function associated with successful reperfusion. Global left ventricular function (assessed in the 30 degrees right anterior oblique projection with the area/length method) and infarct zone wall motion (studied with the centerline method) were evaluated at least 4 weeks after the event. Reperfusion was thought to be achieved when ST segment elevation dropped > 50% relative to the most abnormal peak documented at any time in the study. Eighty patients (78%) met the criterium for successful reperfusion (group 1), and 23 (22%) did not (group 2). Both groups had similar clinical and angiographic characteristics. All indexes of global left ventricular function were significantly better in group 1 than in group 2 patients (end-diastolic volume: 176 +/- 51 vs. 209 +/- 76 ml, end-systolic volume: 66 +/- 40 vs. 97 +/- 55 ml, ejection fraction: 65 +/- 13 vs. 57 +/- 11%, respectively, all P < 0.02). Also the severity (-1.6 +/- 1.3 vs. -2.6 +/- 1.01 S.D./chord, respectively, P < 0.001) and the extension of hypokinesia in the infarct zone (number of chords with > 2 S.D.: 13 +/- 16 vs. 28 +/- 17, respectively, P < 0.0001) were less in group 1 than in group 2 patients. Furthermore, in reperfused patients, both global left ventricular function and regional wall motion were better in those admitted < 60 min from onset of pain. In conclusion, patients with rapid ( > 50%) decrease of ST segment elevation have smaller infarct size and better global left ventricular function than patients without electrocardiographic signs of reperfusion as assessed by continuous ST segment monitoring. This suggests that this non-invasive technique is a powerful tool able to identify patients most benefiting from thrombolytic therapy.

Prehospital thrombolysis in rural emergency room and subsequent transport to a coronary care unit: Ravenna Myocardial Infarction (RaMI) trial

OBJECTIVE

To assess the feasibility, safety and efficacy of thrombolysis in the Emergency Room of a Rural Hospital with no Coronary Care Unit, and subsequent transfer to the Coronary Care Unit of a City Hospital.

DESIGN

Prospective study, controlled with two parallel groups of consecutive patients (Group 1: Rural Hospital, Group 2: CCU Ravenna) and administration of Anistreplase 30 intravenous unit.

SETTING

Rural Emergency Rooms which transmitted the electrocardiogram by cardiotelephone to the Ravenna Coronary Care Unit (average distance 35 km; range: 17-50 km).

PATIENTS

280 (Group 1: 102 patients, Group 2: 178 patients) with suspected acute myocardial infarction and with no contra-indications to fibrinolysis, within 6 h of onset of symptoms.

MAIN OUTCOME MEASURES

time saving, accuracy of diagnosis, adverse events, left ventricular function and survival.

RESULTS

the median pain to needle time was 90' in Group 1 and 165' in Group 2 (P < 0.001). Accuracy of diagnosis for acute myocardial infarction was 91% and 100%, respectively. Complications were rare and none occurred during transfer. The creatine phosphokinase peak of Group 1 was lower than Group 2 (1389 vs. 2186 IU/l; P < 0.001). The echocardiographic Wall Motion Abnormality Score Index of Group 1 was lower than Group 2 (3.571 vs. 5.589; P < 0.001). Mortality at 35 days in Group 1 was 7.5% vs. 10.7% in Group 2 (-30%; P = n.s.).

CONCLUSIONS

The Emergency Room physician, in close collaboration with the cardiologist, supplied a very high standard of pre-Coronary Care Unit diagnosis and therapy. Administration of Anistreplase in the rural Emergency Room brought about a significant reduction of pain to needle time, a significant improvement in left ventricular function and a reduction in mortality.

[The evolution of hospital mortality due to acute myocardial infarct in the first 2 GISSI studies. Participants in the GISSI 1 and GISSI 2 studies. Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico]

During the short while of 5 years, between 1984 and 1985, two large clinical trials have been performed in Italy concerning fibrinolytic therapy in Acute Myocardial Infarction: GISSI 1 and GISSI 2. They made possible to evaluate the evolution of demographic and clinical features, the in-hospital mortality rate, and the causes of death of a huge number of patients admitted to CCU throughout the whole country. Out of 31,826 patients with acute myocardial infarction admitted to 176 CCU participating to the GISSI 1 16.9% were 75 years old and 24.7% were females; 21.8% and 26.4% were the percentages in the 38,086 patients admitted to the 223 CCU participating in the GISSI 2. Despite the higher prevalence of the two demographic characteristic with the worse prognosis, the in-hospital mortality rates were respectively 12.2% in the GISSI 1 and 10.0% in the GISSI 2 studies, with a statistically significant decrease (RR 0.84; C.L. 0.80-0.88). The significant decrease in the in-hospital mortality concerns also the patients populations selected according to the same criteria of inclusion in the two trials (within 6 hours from the onset of symptoms and with only ST elevation at the ECG of admission) and to the treatment with fibrinolytic drug (SK or rtPA). As a matter of fact 468 patients died of the 4,696 (10.0%) treated with SK in the GISSI 1 against 1,092 patients of 12,381 (8.8%) enrolled in the GISSI 2 and treated with SK or rtPA (RR 0.87; L.C. 0.78-0.98). The reduction of in-hospital mortality may be explained by some differences in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)