Dependence on the thermodynamic state of self-diffusion of pseudo-hard-sphere and Lennard-Jones potentials.

Self-diffusion D in a system of particles that interact with a pseudo-hard-sphere or a Lennard-Jones potential is analyzed. Coupling with a solvent is represented by a Langevin thermostat, characterized by the damping time t_{d}. The hypotheses that D=D_{0}φ is proposed, where D_{0} is the small concentration diffusivity and φ is a thermodynamic function that represents the effects of interactions as concentration is increased. Molecular dynamics simulations show that different values of the noise intensity modify D_{0}, but do not have an effect on φ. This result is consistent with the assumption that φ is a thermodynamic function since the thermodynamic state is not altered by the presence of damping and noise.

Thyroid dysfunction in COVID-19 patients.

PURPOSE: "Non thyroidal illness syndrome" (NTIS) or "euthyroid sick syndrome" (ESS) is a possible biochemical finding in euthyroid patients with severe diseases. It is characterized by a reduction of serum T3 (fT3), sometimes followed by reduction of serum T4 (fT4). The relationship between thyroid hormones levels and mortality is well known and different studies showed a direct association between NTIS and mortality. The sudden spread of the 2019 novel coronavirus (SARS-CoV 2) infection (COVID-19) and its high mortality become a world healthcare problem. Our aim in this paper was to investigate if patients affected by COVID-19 presented NTIS and the relationship between thyroid function and severity of this infection. METHODS: We evaluated the thyroid function in two different groups of consecutive patients affected by COVID-19 with respect to a control group of euthyroid patients. Group A included patients hospitalized for COVID-19 pneumonia while patients requiring intensive care unit (ICU) for acute respiratory syndrome formed the group B. Group C identified the control group of euthyroid patients. RESULTS: Patients from group A and group B showed a statistically significant reduction in fT3 and TSH compared to group C. In group B, compared to group A, a further statistically significant reduction of fT3 and TSH was found. CONCLUSIONS: COVID-19 in-patients can present NTIS. FT3 and TSH serum levels are lower in patients with more severe symptoms.

Malignant stromal tumor consistent with fibrosarcoma arising from Meckel's diverticulum. Clinicopathological study of an incidentally discovered tumor and review of the literature.

The authors report a case of a Meckel's diverticulum mesenchymal tumor incidentally discovered in a 69-year-old woman undergoing laparotomy for an ovarian cyst. Histological examination of the tumor revealed a fasciculated proliferation of spindle cells that proved to be immunoreactive to vimentin only; pleomorphism was mild, necrosis extensive and mitotic count high. Because these features were consistent with those of fibrosarcoma, the tumor was classified in the category of gastrointestinal stromal tumors; more specifically, it was considered malignant for the presence of spread beyond the primary site in the form of peritoneal nodules and for the high mitotic count. We have been able to find only one previously reported case of mesenchymal malignant tumor of Meckel's diverticulum classified as fibrosarcoma among the 199 malignant tumors described in the literature. Based on this personal experience and on the review of the literature concerning malignant tumors of Meckel's diverticulum, we discuss both the rarity of these tumors and the importance of removing Meckel's diverticulum every time it is found during laparotomy.