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Biomedical subjects

D Mancini

Publications and source records attributed to D Mancini.

66 records · Page 4Linked to original sources
PubMed1979

Significance of early increase in stable and radioactive plasma calcium after parathyroidectomy in primary hyperparathyroidism.

Early effects of parathyroid hormone (PTH) deficiency were studied in 12 patients with primary hyperparathyroidism due to single parathyroid adenoma by following the precise time course of changes in plasma calcium (Ca) and immunoreactive parathyroid hormone (IPTH) after parathyroid surgery and by prelabeling 2 patients with radiocalcium (Ca*). Surgical removal of the adenoma was immediately followed by a sudden increase in plasma Ca which preceded the usual fall. The increase in plasma Ca commenced simultaneously with the fall in iPTH and was accompanied by a parallel increase in specific activity (sp. act.) of plasma Ca*. Specific activity continued to rise for 2 h in both prelabeled patients, whereas blood calcium was already falling thereafter reaching a markedly low removal rate constant as long as plasma Ca decreased. When plasma Ca began to rise, sp. act. resumed a descending course. Our findings indicate that the initial hypercalemia depends on PTH withdrawal and results from a rapid flux into general extracellular fluid (ECF) of calcium coming from a compartment with higher sp. act., contained within the miscible pool, immediately followed by a reduction in calcium transfer from bone. These results suggest that acute PTH deficiency determines an outflow of calcium from bone cells and support the theory that PTH initiates its action by modifying their intracellular calcium content.

Adenoma↗
PubMedDate not supplied

Ground-based telescope pointing and tracking optimization using a neural controller.

Neural network models (NN) have emerged as important components for applications of adaptive control theories. Their basic generalization capability, based on acquired knowledge, together with execution rapidity and correlation ability between input stimula, are basic attributes to consider NN as an extremely powerful tool for on-line control of complex systems. By a control system point of view, not only accuracy and speed, but also, in some cases, a high level of adaptation capability is required in order to match all working phases of the whole system during its lifetime. This is particularly remarkable for a new generation ground-based telescope control system. Infact, strong changes in terms of system speed and instantaneous position error tolerance are necessary, especially in case of trajectory disturb induced by wind shake. The classical control scheme adopted in such a system is based on the proportional integral (PI) filter, already applied and implemented on a large amount of new generation telescopes, considered as a standard in this technological environment. In this paper we introduce the concept of a new approach, the neural variable structure proportional integral, (NVSPI), related to the implementation of a standard multi layer perceptron network in new generation ground-based Alt-Az telescope control systems. Its main purpose is to improve adaptive capability of the Variable structure proportional integral model, an already innovative control scheme recently introduced by authors [Proc SPIE (1997)], based on a modified version of classical PI control model, in terms of flexibility and accuracy of the dynamic response range also in presence of wind noise effects. The realization of a powerful well tested and validated telescope model simulation system allowed the possibility to directly compare performances of the two control schemes on simulated tracking trajectories, revealing extremely encouraging results in terms of NVSPI control robustness and reliability.

Models, Theoretical↗
PubMedDate not supplied

Cardiac assist devices for end-stage heart failure.

Cardiac assist devices have become an important therapy for patients with end-stage cardiac failure. These devices continue to evolve. Most current devices provide temporary, left-sided support for patients with cardiogenic shock from postcardiotomy syndrome or for patients awaiting cardiac transplantation. The two most frequently used left ventricular assist devices as a bridge to transplant are the Thermocardiosystems (HeartMate I) and the Novacor devices. The selection criteria for the use of these devices and treatment of these patients will be reviewed. Additionally, other currently available devices and future devices are also presented and discussed.

Cardiovascular Surgical Procedures↗
PubMedDate not supplied

Percutaneous balloon aortic valvuloplasty as a bridge to heart transplantation.

Despite high rates of restenosis and recurrent symptoms, percutaneous aortic balloon valvuloplasty may be a useful alternative therapy to surgery in certain patients with aortic stenosis. In this case report, we describe a potentially new indication for this procedure, namely to reduce symptoms and stabilize a patient before heart transplantation. Our patient with class IV heart failure benefited from valvuloplasty with fewer symptoms and was able to be discharged while awaiting transplantation, which was successfully performed 2 months later. Percutaneous aortic balloon valvuloplasty should be considered as a palliative procedure in patients with severe aortic stenosis who are awaiting heart transplantation.

Aortic Valve↗
PubMedDate not supplied

Additive value of immunologic monitoring to histologic grading of heart allograft biopsy specimens: implications for therapy.

BACKGROUND: Currently the sole method available for diagnosis of heart allograft rejection is endomyocardial biopsy. Although this procedure offers important criteria for treatment, it cannot always discriminate between mild episodes of rejection which might be self-limiting and forms which may progress. In an effort to monitor rejection, we have implemented a cellular monitoring strategy aimed at identifying episodes of rejection in biopsy specimens which may evolve into higher grades of rejection. The lymphocyte growth assay is based on the capacity of interleukin-2 receptor-positive T cells to expand in the presence of interleukin-2 and antigen provided by the biopsy fragment. In this study we investigated whether a positive lymphocyte growth assay correlated with and was predictive of subsequent histologic allograft rejection and the development of anti-human leukocyte antigen antibodies. METHODS: Lymphocyte growth assay was performed on 437 biopsy specimens from 76 patients. Patients with mild allograft rejection defined as grade 2 rejection were randomized to treatment according to the results of the lymphocyte growth assay. Anti-human leukocyte antigen antibodies was also measured monthly. Cells grown from the biopsy specimens were tested against the donor cells and allopeptides derived from the donor human leukocyte antigen-DR. RESULTS: A highly significant correlation was observed between the histologic grade of rejection and growth of graft infiltrating cells (p < 0.0001). Lymphocyte growth occurred in 10% of grade 0 versus 60% of grade 3A biopsy specimens. Only 4% of histologically negative cases with negative lymphocyte growth assay progressed to rejection in the next month. In the randomized study in which treatment was based on the lymphocyte growth assay results, progressive rejection occurred in three of four cases with positive lymphocyte growth assay versus only 1 of 11 with a negative lymphocyte growth assay (p < 0.001). A highly significant correlation was found between a positive lymphocyte growth assay and subsequent development of antihuman leukocyte antigen antibodies (p < 0.0006). This finding indicates that cellular rejection evidenced by lymphocyte growth assay ultimately results in humoral antihuman leukocyte antigen antibody mediated rejection. Limiting dilution analysis showed that although the direct recognition pathway prevails in early rejection, cells participating in the indirect pathway also proliferate vigorously in the graft during rejection. CONCLUSIONS: Monitoring of rejection with lymphocyte growth assay is a simple method which provides prognostic information on the outcome of cardiac allografts. Lymphocyte growth assay correlates with histologic rejection and is predictive of future histologic rejection episodes. Lymphocyte growth assay also predicts subsequent development of antihuman leukocyte antigen antibodies and thus may provide a useful method for ascertaining the onset of chronic rejection.

Adult↗