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Objectives The purpose of this study was to compare myocardial perfusion imaging (MPI) with high-speed single-photon emission computed tomography (SPECT) with conventional SPECT imaging for the evaluation of myocardial perfusion in patients with known or suspected coronary artery disease. Background A novel technology has been developed for high-speed SPECT MPI by employing a bank of independently controlled detector columns with large-hole tungsten collimators and multiple cadmium zinc telluride crystal arrays. Methods A total of 44 patients (39 men) underwent same-day Tc-99m sestamibi stress/rest MPI. High-speed SPECT images were performed within 30 min after conventional SPECT. Stress and rest acquisition times were 16 and 12 min for conventional imaging and 4 and 2 min for high-speed SPECT, respectively. Myocardial counts/min (cpm) were calculated for both conventional SPECT and high-speed SPECT. Images were visually analyzed, and the summed stress score (SSS) and summed rest score (SRS) were calculated. Image quality and diagnostic confidence were qualitatively assessed. Results High-speed SPECT SSS and SRS correlated linearly with conventional SPECT respective scores (r = 0.93, p Conclusions High-speed SPECT provides fast MPI with high image quality and up to 8 times increased system sensitivity. The amount of perfusion abnormality visualized by high-speed SPECT is highly correlated to conventional SPECT, with an equivalent level of diagnostic confidence.

Purpose: This research is aimed at studying the possibilities of the long-term preservation of thyrocytes xenogenic culture in the recipient without using immunosuppressive therapy. Material and Methods: The research was carried out on the experimental model “rabbit-dog.” Using sixteen dogs having undergone total thyroidectomy, a macroencapsulated culture of a rabbit’s thyrocytes was transplanted into the lumen of their arterial blood stream. Results: Morphologic and laboratory research carried out six months later showed the preservation of thyrocytes vitality, the formation of organized thyroid tissue in the vessel’s lumen, and the compensation of experimental primary hypothyroidism. A radioisotopic study showed an active absorption of the isotope by the transplanted thyroid tissue. Conclusions: The macroencapsulation and transplantation of thyrocytes into the blood stream is the most effective method of its long-term preservation.

Purpose: To evaluate intravascular xenotransplantation of macroencapsulated pancreatic islet cells in the process of the treatment of diabetes mellitus type 1 without immunosuppressive therapy. Material and methods: Xenogenic intravascular transplantation was performed in 19 patients with diabetes mellitus (type 1) having high insulin demand and frequent hypo- and hyperglycemic comas without immunosuppressive therapy. The culture was obtained from 3rd trimester rabbit fetuses. Cell culture suspension was encapsulated into microporous macrocapsule made of nylon and grafted into the deep femoral artery or theforearm cubital vein after performing arteriovenous anastomosis. Results: For 2 years after transplantation, positive results were observed in 14 recipients (73.7%). The total decrease of insulin demand was 60-65%, and hypo- and hyperglycemic comas disappeared completely, while C-peptide and immunoreactive insulin levels significantly increased, reversely correlating with the fructosamin level, as a protein glycation marker . Conclusions: Xenotransplantation of pancreatic islet cells is a beneficial alternative to allotransplantation, which allows to overcome allogenic cell deficit. Macroencapsulation of islet cells with their subsequent grafting into the vascular lumen creates double immune isolation and allows overcoming acute and chronic graft rejection without immuno- suppressive therapy. It considerably decreases insulin demand, compensates hypo- and hyperglycemic conditions, makes the course of diabetes stable, and improves the quality of patients’ life.

The article presents a new method of surgical treatment of experimental diabetes mellitus in a rabbit to dog model. Rabbit islet cells, which had been macroencapsulated into a microporous polyamide, were implanted into the dog aorta without immunosuppressive therapy. Euglycemia was reached at 4 to 5 days and persisted for 12 months. Morphological and immunohistochemical investigations showed long-term preservation of islet cell viability, absence of graft rejection, and formation of a biological artificial pancreas in the capsule at 6 months after transplantation. Up to 60% of transplanted cells were still viable 12 months later. The major factor contributing to preservation of islet cells is neo-angiogenesis, which develops during the first weeks after transplantation. Double immune isolation of islet cells by macroencapsulation with implantation into the blood stream allows the use of either xenotransplantation or allotransplantation.

We have previously obtained stimulated emission at 300°K from CaF2YF3Nd3+ [1]. The present work reports the experimental results of a spectral investigation of the stimulated radiation emission of the transition 4F32 → 4I1 1 2 of the Nd3+ ion in CaF2YF3 at 300°K. The laser action was investigated in crystals which had a Nd3+ ion concentration ranging from 0.5 to 1.0% and YF3 from 0.5 to 5%, and were grown from the melt in a fluorinating atmosphere by the modified Bridgman technique [2]. At 300°K three laser lines were detected.