The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum Δ V capability of 600  ms - 1 . Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes - B1, provided by the Japanese space agency, JAXA, and B2 - that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.

Spectrum of rare and common genetic variants in arrhythmogenic cardiomyopathy

Background

Arrhythmogenic cardiomyopathy (ACM) is a rare inherited cardiac disorder, whose genetic cause is elusive in about 50% of cases. ACM pathogenic mutations mainly involve desmosomal genes (PKP2, JUP, DSP, DSG2, DSC2). ACM presents a variable disease course, spanning from mild electrocardiographic alterations and/or contractile dysfunctions, to malignant ventricular arrhythmias and heart failure.

Purpose

In an attempt to broaden etiological diagnosis for ACM patients, this work was aimed at finding potential rare high-impact variants in genes not previously associated with ACM. Secondarily, we meant to assess the impact of genetic polymorphisms on the disease clinical severity.

Methods

We clinically characterized 82 consecutive ACM probands and performed next-generation sequencing, exploring a panel of 174 genes associated with inherited cardiovascular diseases. We evaluated the pathogenicity of rare variants, according to the American College of Medical Genetics / Association for Molecular Pathology guidelines, to select candidates with potential ACM causative role. Further, a genotype-phenotype correlation analysis between common polymorphisms and clinical variables was performed to find genetic factors associated with specific ACM phenotypes. Finally, we carried out event-free survival analyses, linking specific variants to arrhythmias in 8,6±0,7 years follow-up, to estimate their possible impact on arrhythmic risk.

Results

We identified 141 rare genetic variants, of which 23 were classified of high impact, including variants in genes never associated with ACM (e.g. ABCC9, APOB, MIB1). These genes deserve future studies as they could participate in ACM pathogenesis. In addition, we found 69 genotype-phenotype significant associations (p≤0.005) between common variants and clinical parameters. Variants associated to arrhythmic phenotypes were found with genes linked to arrhythmias (e.g. KCNQ1, HCN4) and other cardiomyopathies (e.g. MYBPC3, MYL2). Associations involving substrate impairments were found with genes linked to muscle dysfunctions (e.g. LAMA2, SGCD). Arrhythmia-associated polymorphisms, included in survival analyses, were found to be associated with an increased occurrence of arrhythmic events during patients' follow-up.

Conclusion

The identification of rare high impact variants in novel genes potentially associated with ACM and the observation of genotype-phenotype correlations constitute the starting point to address the current lack of knowledge of the genetic landscape of ACM.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministero Italiano della Salute - Ricerca corrente

Interaction of methadone with didanosine and stavudine

For opiate-dependent injection drug users infected with HIV, methadone therapy may facilitate adherence to complex highly active antiretroviral therapy (HAART) regimens. Current HAART regimens include one or more nucleoside analogues. We investigated the effects of methadone on the pharmacokinetics of the tablet formulation of didanosine (ddI) and of stavudine (d4T) in 17 study subjects on stable methadone therapy and in 10 untreated controls. Methadone treatment reduced the measured areas under the time-concentration curve (AUC0-6) by 63% for ddI (p =.04) and by 25% for d4T (p =.005) and the extrapolated AUCs for the full dosing interval (AUC0-12) by 57% for ddI (p =.11) and by 23% for d4T (p =. 02). Peak drug concentrations (Cmax) were reduced by 66% (p =.007) and 44% (p =.001) for ddI and d4T, respectively. The effects on AUC and Cmax appeared to result primarily from decreases in bioavailability. Methadone also delayed drug absorption. Trough levels for methadone did not differ significantly from those in historical controls, suggesting that ddI and d4T did not substantially alter methadone disposition. The results suggest that larger doses of the tablet formulation or an alternate formulation may be needed when didanosine is given to study subjects treated with methadone.

Hepatitis B viral nucleotide sequences in non-A, non-B or hepatitis B virus-related chronic liver disease

The presence of serological markers of hepatitis B virus (HBV) infection and of hepatocellular HBV DNA were investigated in 19 HBsAg-negative patients with clinically and histologically significant chronic liver disease. Four cases negative for antibodies to HBsAg (anti-HBs), to the core antigen (anti-HBc), and to the e antigen (anti-HBe) were classified as non-A, non-B hepatitis. The remainder, positive for one or more of the three antibodies, were classified as hepatitis B. Histologic diagnosis was chronic active hepatitis in five, chronic persistent hepatitis in 11, micronodular cirrhosis in two, and fatty liver in one patient. The DNA extracted from limited amounts of liver biopsies, without cleavage by restriction endonucleases, was analyzed by the Southern blot technique for the presence of episomal HBV DNA. Autoradiographs showed a single band of less than 4.0 kilobase (kb) corresponding to the monomeric form of HBV DNA in five patients, several bands of larger forms (4.0 to 18.0 kb) in three patients, both the monomeric and the larger forms in eight patients, and no HBV DNA in three patients. While HBV DNA was detected in the hepatocellular DNA of six patients who underwent splenectomy, hybridization was negative with the DNA extracted from their spleens. The episomal viral DNA larger than 4.0 kb may represent concatemeric forms or free oligomers which could not be distinguished from rearranged and/or integrated viral DNA in the limited analyses of the hepatocellular DNA hydrolyzed with HindIII or EcoRI. Our observations suggest the presence of HBV-like agents in the liver of serologically HBsAg-negative patients with chronic liver disease.

Characterization of human T lymphocyte subpopulations (TG and T non G): cytologic examination and cytographic analysis

Two T lymphocyte subpopulations were separated with an immunological method. In fact recently two T cell subsets with receptors for the Fc of IgM (TM) and of IgG (TG) respectively have been described. We have specifically separated TG and T non G lymphocytes by the rosetting technique. Cytological examination was performed on the two cell fractions: the results are in agreement with that already reported. Cytographic analysis was also carried out confirming the cytologic results. The possible practical implications of these acquisitions and those already applied are discussed.