MAXIMUM SUBSPACES RELATED TO A-CONTRACTIONS AND QUASINORMAL OPERATORS

Suciu, Laurian Korean Mathematical Society 2008 대한수학회지 Vol.45 No.1

It is shown that if $A{\geq}0$ and T are two bounded linear operators on a complex Hilbert space H satisfying the inequality $T^*\;AT{\leq}A$ and the condition $AT=A^{1/2}TA^{1/2}$, then there exists the maximum reducing subspace for A and $A^{1/2}T$ on which the equality $T^*\;AT=A$ is satisfied. We concretely express this subspace in two ways, and as applications, we derive certain decompositions for quasinormal contractions. Also, some facts concerning the quasi-isometries are obtained.

MAXIMUM SUBSPACES RELATED TO A-CONTRACTIONS AND QUASINORMAL OPERATORS

Laurian Suciu 대한수학회 2008 대한수학회지 Vol.45 No.1

It is shown that if A ≥ 0 and T are two bounded linear operators on a complex Hilbert space H satisfying the inequality T* AT ≤ A and the condition AT = A¹/²TA¹/², then there exists the maximum reducing subspace for A and A¹/²T on which the equality T* AT = A is satisfied. We concretely express this subspace in two ways, and as applications, we derive certain decompositions for quasinormal contractions. Also, some facts concerning the quasi-isometries are obtained. It is shown that if A ≥ 0 and T are two bounded linear operators on a complex Hilbert space H satisfying the inequality T* AT ≤ A and the condition AT = A¹/²TA¹/², then there exists the maximum reducing subspace for A and A¹/²T on which the equality T* AT = A is satisfied. We concretely express this subspace in two ways, and as applications, we derive certain decompositions for quasinormal contractions. Also, some facts concerning the quasi-isometries are obtained.

Grape Seed Extract Effects in Brain After Hypobaric Hypoxia

Adriana Muresan,Soimita Suciu,Doina Daicoviciu,Adriana Gabriela Filip,Simona Clichici 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.9

Hypoxia induces a wide range of deleterious effects at the cellular level due to an increased production of reactive oxygen species (ROS). Polyphenols from grape seeds, which are potent antioxidants might protect the brain against oxidative stress produced by hypobaric hypoxia. The brain effects of three doses of grape seed extract intraperitoneally (i.p.)administered in rats after exposure to hypobaric hypoxia corresponding to 5500m altitude were investigated. Some oxygen and nitrogen reactive species, inflammatory cytokine (IL-6) and molecules involved in angiogenesis (vascular endothelial growth factor [VEGF], matrix metalloproteinase 2 [MMP2], and tissue inhibitors of metalloproteinase 1 [TIMP1]) were determined. Forty-two rats were divided in seven groups: group 1, control; groups 2, 3, and 4 were exposed to hypobaric hypoxia for 24 h in a hypobaric chamber; groups 5, 6, and 7 were exposed to hypobaric hypoxia for 5 days. After returning to normal atmospheric pressure, rats from groups 2 and 5 were sacrificed without other treatment. Animals from groups 3and 6 were i.p treated with carboxymethyl cellulose (CMC) vehicle and those from groups 4 and 7 were i.p. treated with grape seed extract (GSE) (50 mg gallic acid equivalents/kg body weight in 0.5mL CMC suspension/animal). The treatment was applied at 2, 24, and 72 h from returning to normoxia. Hypobaric hypoxia produced increased brain levels of ROS,nitric oxide (NO), IL-6, and VEGF after both time intervals (P < .05). The MMP2 concentration was significantly increased in groups treated only with vehicle, whereas TIMP1 was slightly changed. GSE produced a significant reduction of ROS and NO levels proving its antioxidant capacity. It also decreased IL-6 and MMP2 concentrations to values similar to controls. The VEGF concentration was also significantly reduced. These effects are indicative for anti-inflammatory and antiangiogenic properties of GSE.

Long-Term Survival of Women with Locally Advanced Breast Cancer with ≥10 Involved Lymph Nodes at Diagnosis

Zeichner, Simon Blechman,Cavalcante, Ludimila,Suciu, Gabriel Pius,Ruiz, Ana Lourdes,Hirzel, Alicia,Krill-Jackson, Elisa Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.8

Background: Axillary lymph node status at diagnosis remains the strongest predictor of long-term survival in breast cancer. Patients with more than ten axillary lymph nodes at diagnosis have a poor long-term survival. In this single institutional study, we set out to evaluate the prognosis of this high-risk group in the era of multimodality therapy. Materials and Methods: In this retrospective study, we looked at all breast cancer patients with greater than ten axillary lymph nodes diagnosed at Mount Sinai Medical Center (MSMC) from January 1st 1990 to December 31st 2007 (n=161). In the univariate analysis, descriptive frequencies, median survival, and 5- and 10-year survival rates were estimated for common prognostic factors. A multivariate prognostic analysis for time-to-event data, using the extended Cox regression model was carried out. Results: With a median and mean follow-up of 70 and 89.9 months, respectively, the overall median survival was estimated to be 99 months. The five-year disease-free survival (DFS) was 59.3% and the ten-year DFS was 37.9%, whereas the five- and ten-year overall survival (OS) was 66.6% and 43.9%, respectively. Multivariate analysis revealed a significant improvement in DFS among black patients compared to whites (p=0.05), improved DFS and OS among young patients (ages 21-45) compared to elderly patients (age greater than 70) (p=0.00176, p=0.0034, respectively), and improved DFS and OS among patients whose tumors were ER positive (p=0.049, p=0.0034). Conclusions: In this single institution study of patients with greater than 10 positive axillary nodes, black patients had a significantly improved DFS compared with white patients. Young age and ER tumor positivity was associated with improved outcomes. Using multivariate analysis, there were no other variables associated with statistically significant improvements in DFS or OS including date of diagnosis. Further work is needed to improve breast cancer survival in this subgroup of patients.

miR-31a-5p promotes postnatal cardiomyocyte proliferation by targeting RhoBTB1

Junjie Xiao,Hui Liu,Dragos Cretoiu,Daniela Oana Toader,Nicolae Suciu,Jing Shi,Shutong Shen,Yihua Bei,Joost PG Sluijter,Saumya Das,Xiangqing Kong,Xinli Li 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-

A limited number of microRNAs (miRNAs, miRs) have been reported to control postnatal cardiomyocyte proliferation, but their strong regulatory effects suggest a possible therapeutic approach to stimulate regenerative capacity in the diseased myocardium. This study aimed to investigate the miRNAs responsible for postnatal cardiomyocyte proliferation and their downstream targets. Here, we compared miRNA profiles in cardiomyocytes between postnatal day 0 (P0) and day 10 (P10) using miRNA arrays, and found that 21 miRNAs were upregulated at P10, whereas 11 were downregulated. Among them, miR-31a-5p was identified as being able to promote cardiomyocyte proliferation as determined by proliferating cell nuclear antigen (PCNA) expression, double immunofluorescent labeling for α-actinin and 5-ethynyl-2-deoxyuridine (EdU) or Ki-67, and cell number counting, whereas miR-31a-5p inhibition could reduce their levels. RhoBTB1 was identified as a target gene of miR-31a-5p, mediating the regulatory effect of miR-31a-5p in cardiomyocyte proliferation. Importantly, neonatal rats injected with a miR-31a-5p antagomir at day 0 for three consecutive days exhibited reduced expression of markers of cardiomyocyte proliferation including PCNA expression and double immunofluorescent labeling for α-actinin and EdU, Ki-67 or phospho-histone-H3. In conclusion, miR-31a-5p controls postnatal cardiomyocyte proliferation by targeting RhoBTB1, and increasing miR-31a-5p level might be a novel therapeutic strategy for enhancing cardiac reparative processes.

Challenges in Perioperative Animal Care for Orthotopic Implantation of Tissue-Engineered Pulmonary Valves in the Ovine Model

Al Hussein Hussam,Al Hussein Hamida,Sircuta Carmen,Cotoi Ovidiu S.,Movileanu Ionela,Nistor Dan,Cordos Bogdan,Deac Radu,Suciu Horatiu,Brinzaniuc Klara,Simionescu Dan T.,Harpa Marius M. 한국조직공학과 재생의학회 2020 조직공학과 재생의학 Vol.17 No.6

Background: Development of valvular substitutes meeting the performance criteria for surgical correction of congenital heart malformations is a major research challenge. The sheep is probably the most widely used animal model in heart valves regenerative medicine. Although the standard cardiopulmonary bypass (CPB) technique and various anesthetic and surgical protocols are reported to be feasible and safe, they are associated with significant morbidity and mortality rates. The premise of this paper is that the surgical technique itself, especially the perioperative animal care and management protocol, is essential for successful outcomes and survival. Methods: Ten juvenile and adult female sheep aged 7.8–37.5 months and weighing 32.0–58.0 kg underwent orthotopic implantation of tissue-engineered pulmonary valve conduits on beating heart under normothermic CPB. The animals were followed-up for 6 months before scheduled euthanasia. Results: Based on our observations, we established a guide for perioperative care, follow-up, and treatment containing information regarding the appropriate clinical, biological, and ultrasound examinations and recommendations for feasible and safe anesthetic, surgical, and euthanasia protocols. Specific recommendations were also included for perioperative care of juvenile versus adult sheep. Conclusion: The described surgical technique was feasible, with a low mortality rate and minimal surgical complications. The proposed anesthetic protocol was safe and effective, ensuring both adequate sedation and analgesia as well as rapid recovery from anesthesia without significant complications. The established guide for postoperative care, follow-up and treatment in sheep after open-heart surgery may help other research teams working in the field of heart valves tissue regeneration.