Reconsidering some aspects of the two-trials paradigm

A common standard for the demonstration of efficacy in a clinical submission is a statistically significant outcome in at least two pivotal trials ("two-trials convention"). When the data structures in different trials are sufficiently similar to allow pooling of the data across trials for a combined analysis, we argue here that such an analysis is a more logical and efficient basis for a judgment regarding efficacy. Criteria for combined analyses may be established, which ensure the same false positive rate protection as the two-trials convention. A combined analysis will generally have much more power than the corresponding application of the two-trials approach that has the same false positive rate protection. In addition, we describe the behavior of modified versions of pure combined analysis, which incorporate a formal standard for reproducibility of trial results by limiting the larger of the individual trial p-values. These modifications are shown to maintain the desirable behavior of the pure combined analysis, namely, higher power compared to the two-trials convention.

Stretched exponential relaxation in a diffusive lattice model

We studied the single dimer dynamics in a lattice diffusive model as a function of particle density in the high densification regime. The mean square displacement is found to be subdiffusive both in one and two dimensions. The spatial dependence of the self-part of the van Hove correlation function displays as a function of r a single peak and signals a dramatic slow down of the system for high density. The self-intermediate scattering function is fitted to the Kohlrausch-Williams-Watts law. The exponent beta extracted from the fits is density independent while the relaxation time tau follows a scaling law with an exponent 2.5.

[The effect of instrumentation on original apical foramen shape using steel vs niti rotatory: computerized analysis]

BACKGROUND

A fundamental requirement to obtain a correct endodontic preparation depends on the respect, during cleaning and shaping, of the original morphology of the apical foramen, (AF), so that the filling material will form a complete seal.

METHODS

In our previous studies, in order to verify if this presumption was respected using rotary NiTi instruments with cutting tip, we instrumented extracted teeth characterised by a different degree of root curvatures. Using a standardized system to replace the sample, the original shape of the apical foramen of each tooth was recorded using a computerised technique and then compared to the shape after instrumentation. The data showed differences on AF shapes depending on the degree of root canal curvatures. In fact, the teeth with straight canals showed the least alterations on the original AF shape; on the contrary, the teeth with curved canals showed apical foramen enlargement or transportation. Therefore, in the current study we aimed to compare the in vitro effects of stainless steel, (Flexofile, Dentsply Maillefer, Baillaigues, Switzerland), vs NiTi safe cutting tip (Quantec SC, (Tycom Dental, Irvine CA, U:S.A.), vs NiTi non cutting tip, (Quantec LX, Tycom Dental, Irvine CA, U:S.A.), instrumentation on original apical foramen shape. We used NiTi instruments according to standard technique suggested by Tycom, and hand steel files, to instrument the apical third, according to the Crown-Down technique. Working length was fixed at -0.5 from AF.

RESULTS AND CONCLUSIONS

Our results suggested that in the presence of accentuated canal curves rotary Niti, with cutting tip, cause significantly more enlargement of the AF area. At the same time, we also observed that NiTi rotary files, with both cutting and non-cutting tip, cause eccentric enlargement of AF in curved canals. Therefore, NiTi engine-driven instruments should be used carefully in the presence of accentuated canal curves to avoid enlargement or transportation of AF, probably because rotary NiTi files may slip out of operative control, leaving a mark on the foramen shape. In the presence of severe curves, we suggest modifying the operative sequences by alternating rotary NiTi with hand NiTi or stainless steel instruments, especially in the preparation of apical third.

[Request of dental care and periodontal treatment needs in a population sample of Palermo]

BACKGROUND

The organisation of periodontal health prevention programmes must take into account the public level of awareness of the periodontal diseases. The aim of the present investigation was to assess the relationships between the request of dental care and the periodontal treatment needs in a population sample of Palermo.

METHODS

The study population consisted of 554 out-patients, consecutively examined during 18 months (January 1999 to June 2000) at the Palermo University Department of Oral Sciences. All participants answered a written questionnaire concerning the cause for the request of dental care and periodontal symptoms. Periodontal treatment needs were assessed using the Community Periodontal Index of Treatment Needs (CPITN).

RESULTS

Statistical analysis (Chi-Square Test, Fisher's Exact Test) showed significant discrepancies between the request of dental care and the periodontal treatment needs, poor awareness of periodontal diseases and low perception of their symptoms by the patients.

CONCLUSIONS

These findings showed that the awareness of periodontal diseases by the population examined is poor. This could be due either to the lack or failure of public education programmes on periodontal health. Yet, it could be related to an inadequate dentists' awareness of the periodontal diseases. Such findings should be considered in the planning of periodontal health programmes in relation to the population of Palermo.

Cerebrospinal fluid examination in the differential diagnosis of inflammatory myelopathies

Among the diagnostic procedures aimed at defining the etiology and the pathogenesis of inflammatory myelopathies, the examination of the cerebrospinal fluid (CSF) plays a central role. Indeed, for several autoimmune and inflammatory syndromes and diseases involving the spinal cord, in addition to immunological screening of the blood, a detailed analysis of the CSF may allow the achievement of the diagnosis. Routine CSF analysis should include a detailed cytology, the evaluation of the blood-brain barrier dysfunction, quantitative and qualitative analysis of the intrathecal IgG synthesis (i.e. calculation of the IgG index and demonstration of oligoclonal IgG bands), and immunological and virological tests based on immunoenzymatic (ELISA, RIA) and molecular biology techniques (PCR, nested PCR). A more advanced step includes fluorescence-activated cell sorting (FACS) analysis of CSF lymphocytes, and, when possible, virological and immunological tests on cell culture supernatants.

Pathological findings of HIV-associated cardiovascular disease

More effective therapies have improved survival times of HIV+ patients, resulting in a higher prevalence of long-term complications of the disease. This review focuses on HIV-associated cardiovascular pathology, correlating the morphologic findings to clinical syndromes of HIV disease/AIDS.

The range of multiple sclerosis associated with neurofibromatosis type 1

Multiple sclerosis associated with neurofibromatosis type 1 (NF1) is a very rare event. Seven patients with multiple sclerosis and NF1 are described in the literature, and all were reported to have the primary progressive form of multiple sclerosis. Three new patients with NF1 that developed multiple sclerosis are described and it is shown that the range of multiple sclerosis associated with NF1 includes the relapsing forms of the disease. The risk of having both NF1 and multiple sclerosis in north east Italy is higher than would be expected based on the prevalence rates of the two diseases.

Arrhythmogenic right ventricular cardiomyopathy: clinicopathologic correlation based on a revised definition of pathologic patterns

Different morphologic features of arrhythmogenic right ventricular cardiomyopathy (ARVC) have been described. However, it is still unclear whether they correspond to distinct forms of the same disease. A pathologic study was performed on a series of ARVC (15 from heart transplant and 12 from autopsy) from 2 Italian referral university hospitals. Based on both myocellular features and the nature of myocardial replacement, hearts were divided into 2 groups: infiltrative, with a lacelike pattern of transmural fatty infiltration and strands of normal residual cardiomyocytes (n = 11); and cardiomyopathic, with massive myocardial replacement by fibro fatty tissue and cardiomyopathic changes (such as hypertrophy and myofibril loss) of residual cardiomyocytes (n = 16). Hearts from the infiltrative group were mostly obtained at autopsy of patients who died suddenly. Fatty substitution was limited almost exclusively to the right ventricle. Mitral valve dysplasia (prolapse or cleft) was frequently present. Hearts from the cardiomyopathic group came mainly from heart transplants for congestive heart failure. Fibro fatty replacement was more extensive, usually biventricular. Active myocarditis and features suggestive of myocardial transdifferentiation were also observed. Despite these differences in clinical outcome and morphologic features, patients from the 2 groups showed similar mean age, sex distribution, occurrence of threatening ventricular arrhythmias, and prevalence of family history of sudden death, arrhythmias, or cardiomyopathy. Infiltrative and cardiomyopathic patterns represent different clinical and pathologic subsets of ARVC. Myocellular features are an important clue in the distinction between the two entities. The differentiation between the 2 patterns is feasible on endomyocardial biopsy and could give important prognostic information.

Hemorrhage in cerebral metastasis from angiosarcoma of the heart: case report

The purpose of this article is to describe the clinical and pathological features of metastatic angiosarcoma in the central nervous system. Only a few cases of cerebral metastasis from angiosarcoma of the heart have been recorded in the literature; particularly related to intracerebral hemorrhage. A case of secondary cerebral angiosarcoma of the heart in a 33 years old man is presented. The initial symptoms were headache, vomiting, lethargy and aphasia. There was a mass in the left temporal lobe with hemorrhage and edema on the computerized tomography (CT). After 24 hours the neurological status worsened and another CT scan showed rebleeding on the tumor area. He underwent an emergency craniotomy but died two days after. Considering the longer survival of sarcoma patients with new modalities of treatment, the incidence of brain metastasis may increase, demanding a better preventive and more aggressive approach. Besides, due to the hemorrhagic nature of such lesions, we suggest the immediate surgery to prevent a fast and lethal evolution because rebleeding.

Home palliative care as a cost-saving alternative: evidence from Catalonia

The aim of this study was to provide a comparative assessment of the health care resources consumed during the final month of life of patients undergoing palliative treatment and who died from cancer in the town of Mataró, Spain, in 1998, with respect to whether they benefited from home care teams or not. Relevant differences in the use of health care resources were found between the groups. Patients in the standard care group presented more hospital care admissions and longer length of stay, higher use of emergency and outpatient visits, and greater use of palliative care units within nursing homes than patients in the home care group. The monetary quantification of the use of the above-mentioned resources showed a 71% increase in the cost per patient in the standard care when compared to home care. According to the results of this study, home care teams for terminal cancer patients allow for savings to the health care system. A series of policy making and health services research implications are discussed.

Increased expression of thyroid hormone receptor isoforms in end-stage human congestive heart failure

Thyroid hormone plays an important role on myocardial development and function. The local effects of thyroid hormone are mediated by the receptor isoforms ultimately driving the expression of cardiac-specific genes. Although overt and subclinical thyroid dysfunction causes well-known changes in the cardiovascular system, little is known about local thyroid hormone action in normal and failing human myocardium. With a newly developed multiplex competitive RT-PCR method, we evaluated the expression of thyroid hormone receptor (TR) isoforms alpha-1, alpha-2, and beta-1 in normal human hearts and in end-stage congestive heart failure. A statistically significant difference in the expression of all three TR isoforms was observed among samples from normal subjects, ischemic heart disease (IHD), and dilated cardiomyopathy (DCM). In DCM, compared with normal, the studied TR isoforms were significantly increased. In IHD, the increased expression was found significant only for alpha-1 and alpha-2 isoforms. No differences were observed between the pathologic groups. In conclusion, a coordinated increment in the expression of the TR isoforms was observed in both DCM and IHD by multiplex competitive RT-PCR. The observed changes could represent a compensatory mechanism to myocardial failure or to locally altered thyroid hormone action.

Long-term histologic features of synthetic chordal replacement for mitral valve repair: a case report

Expanded polytetrafluoroethylene (e-PTFE) sutures have been used with increasing frequency to replace chordae tendineae in mitral valves prolapsing because of myxoid change. A case is reported where fibrosis and calcification of the endocardial overgrowth covering the synthetic chordae led to severe mitral regurgitation 7 years after plastic repair and required mechanical prosthetic valve implantation.

Interferon-beta (INF-beta) antibodies in interferon-beta1a- and interferon-beta1b-treated multiple sclerosis patients. Prevalence, kinetics, cross-reactivity, and factors enhancing interferon-beta immunogenicity in vivo

We analysed the role of dosage, route and frequency of administration of clinical grade interferon-beta (IFN-beta) preparations in inducing anti-IFN-beta antibodies (IFN-beta-Abs) in 5 groups of relapsing-remitting multiple sclerosis (RRMS) patients who were respectively treated as follows: 1) weekly intramuscular (i.m.) injections of 30 mg of recombinant IFN-beta1a (Avonex), 2) subcutis (s.c.) injections of 250 mg IFN-beta1b (Betaferon) every other day, 3) weekly i.m. injections of 250 mg IFN-beta1b (Betaferon), 4) s.c. injections of 22 mg of IFN-beta1a (Rebif) three times a week, and 5) i.m. injections of 22 mg of IFN-beta1a (Rebif) twice a week. IFN-beta-Abs were determined by ELISA. IFN-beta1b was more immunogenic than IFN-beta1a not only when administered s.c. every other day, but also when administered i.m. at a lower weekly dose; i.m. injection, however, significantly delayed the appearance, and induced lower serum levels of IFN-beta-Abs. In patients treated with s.c. IFN-beta1b, Ab levels peaked 3 to 9 months after therapy initiation, and then slowly, but progressively, declined to pre-therapy levels that in some patients were reached after three years. Patients treated with i.m. or s.c. IFN-beta1a only rarely developed IFN-beta-Abs, and then at very low titers. Overall, the i.m. weekly administration of IFN-beta1a was the less immunogenic treatment. In IFN-beta1b-treated patients, a wash-out period of two/three months was sufficient to bring the IFN-beta-Ab levels below the cut-off. Our findings suggest that the immunogenicity of IFN-beta1a is low, regardless of the route of administration and the dosage, while that of IFN-beta1b is high, and is significantly, but not completely reduced by i.m. administration. As IFN-beta-Abs are cross-reactive, a wash-out period is suggested when the preparation is changed from IFN-beta1b to IFN-beta1a in order to maintain the clinical benefits of the therapy.

Supercooled confined water and the mode coupling crossover temperature

We present a molecular dynamics study of the single-particle dynamics of supercooled water confined in a silica pore. Two dynamical regimes are found. Close to the hydrophilic substrate molecules are below the mode coupling crossover temperature, T(C), already at ambient temperature. The water closer to the center of the pore (free water) approaches upon supercooling T(C) as predicted by mode coupling theories. For free water the crossover temperature and crossover exponent gamma are extracted from power-law fits to both the diffusion coefficient and the relaxation time of the late alpha region.

Valsartan in acute myocardial infarction trial (VALIANT): rationale and design

BACKGROUND

Survivors of acute myocardial infarction (MI) complicated by heart failure and/or resulting in left ventricular dysfunction are at heightened risk for subsequent death and major nonfatal cardiovascular events. Inhibition of the renin-angiotensin system with an angiotensin-converting enzyme inhibitor has consistently been demonstrated to result in reductions in these risks by approximately 20%. The development of angiotensin II receptor blockers offers a new, more specific, and theoretically more complete pharmacologic mode to inhibit the adverse influence of angiotensin II.

METHODS

Valsartan in Acute Myocardial Infarction (VALIANT) is a multicenter, double-blind, randomized, active controlled parallel group study comparing the efficacy and safety of long-term treatment with valsartan, captopril, and their combination in high-risk patients after MI. The trial is designed with 3 arms, giving equal statistical consideration to survival comparisons of captopril versus the angiotensin II receptor blocker valsartan, as well as the combination of captopril plus valsartan, compared with a proven effective dose of captopril. This 14,500-patient trial is designed with an 86% power to detect a 15% reduction in mortality rate with either use of valsartan compared with captopril. The trial encourages optimal individualization of other proven therapies in acute and chronic infarction, and the international patient body ensures good representation of multiple practice patterns.

CONCLUSION

VALIANT is a large international investigative effort that will evaluate the role of valsartan in the management of patients with MI associated with heart failure and/or left ventricular dysfunction. The use of a proven dose of captopril and the comparator arms with valsartan alone or in combination with captopril provides a unique test of whether the angiotensin II receptor blocker can make an additional improvement in clinical outcomes beyond angiotensin-converting enzyme inhibitors.