Publications by authors named "Robert Palazzo"

20 Publications

  • Page 1 of 1

Paucicellular Fibroma of the Ascending Aorta.

Aorta (Stamford) 2021 Oct 12. Epub 2021 Oct 12.

Department of Cardiovascular and Thoracic Surgery, Zucker School of Medicine at Hofstra/Northwell, Manhasset, New York.

Primary tumors of the aorta are extremely rare. To the best of our knowledge, herein, we present the first case in the literature of a paucicellular fibroma originating from the aortic wall.
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http://dx.doi.org/10.1055/s-0041-1730006DOI Listing
October 2021

Risk stratification for nonagenarians undergoing transcatheter aortic valve replacement.

J Card Surg 2020 Feb 15;35(2):294-299. Epub 2019 Nov 15.

Division of Cardiovascular and Thoracic Surgery, Zucker School of Medicine at Hofstra/Northwell, Manhasset, New York.

Background: There are disparate data on the outcomes of nonagenarians undergoing transcatheter aortic valve replacement (TAVR) compared with younger patients. The purpose of this study is to determine whether the Society of Thoracic Surgeons (STS) score can be used to identify the subset of nonagenarians that are at a significantly higher risk for poor postoperative outcomes after TAVR.

Methods: A total of 425 patients above the age of 80 underwent elective TAVR between 12/2013 and 2/2018 and were included in this study. Patients were deemed intermediate or high risk based on an STS predicted the risk of surgical mortality score of 3% to 8% and more than 8%, respectively. Differences in postoperative outcomes and/or 6-month mortality between intermediate and high-risk octogenarians and nonagenarians were compared.

Results: Of the 425 patients, 112 (26.4%) patients were nonagenarians, and 313 (73.6%) patients were octogenarians. Fifty-four (48.2%) of the nonagenarians were stratified as high-risk, while 78 (24.9%) of the octogenarians were stratified as high-risk. There were no statistically significant differences in the composite outcomes between intermediate-risk nonagenarians and intermediate-risk octogenarians. In contrast, high-risk nonagenarians were significantly more likely to experience the composite outcome of major perioperative complications and/or 6-month mortality as compared to high-risk octogenarians.

Conclusion: Intermediate-risk nonagenarians undergoing TAVR have similar postoperative outcomes compared to intermediate-risk octogenarians. However, high-risk nonagenarian patients undergoing TAVR experience significantly poorer outcomes compared to their octogenarian counterparts. Judicious patient selection for TAVR in this subgroup of patients is therefore warranted.
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http://dx.doi.org/10.1111/jocs.14350DOI Listing
February 2020

Acute surgical pulmonary embolectomy: a 9-year retrospective analysis.

Tex Heart Inst J 2015 Feb 1;42(1):25-9. Epub 2015 Feb 1.

Acute pulmonary embolism is a substantial cause of morbidity and death. Although the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines recommend surgical pulmonary embolectomy in patients with acute pulmonary embolism associated with hypotension, there are few reports of 30-day mortality rates. We performed a retrospective review of acute pulmonary embolectomy procedures performed in 96 consecutive patients who had severe, globally hypokinetic right ventricular dysfunction as determined by transthoracic echocardiography. Data on patients who were treated from January 2003 through December 2011 were derived from health system databases of the New York State Cardiac Surgery Reporting System and the Society of Thoracic Surgeons. The data represent procedures performed at 3 tertiary care facilities within a large health system operating in the New York City metropolitan area. The overall 30-day mortality rate was 4.2%. Most patients (68 [73.9%]) were discharged home or to rehabilitation facilities (23 [25%]). Hemodynamically stable patients with severe, globally hypokinetic right ventricular dysfunction had a 30-day mortality rate of 1.4%, with a postoperative mean length of stay of 9.1 days. Comparable findings for hemodynamically unstable patients were 12.5% and 13.4 days, respectively. Acute pulmonary embolectomy can be a viable procedure for patients with severe, globally hypokinetic right ventricular dysfunction, with or without hemodynamic compromise; however, caution is warranted. Our outcomes might be dependent upon institutional capability, experience, surgical ability, and careful patient selection.
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http://dx.doi.org/10.14503/THIJ-13-3877DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4378038PMC
February 2015

Using centrosome fragments in the directed assembly of microtubules.

J Nanosci Nanotechnol 2009 Feb;9(2):871-5

Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA.

In animal cells, microtubules are organized by centrosomes, which are 1-2 microm diameter organelles. The generation of functional centrosome fragments in-vitro through ultrasonication is presented along with microtubule assembly directed by the patterned centrosome fragments. While centrosome fragments are smaller than the fully constituted centrosomes, their microtubule organization function is retained. The centrosome fragment templates offer greater flexibility and better coverage in both patterning and assembly of microtubules when compared with intact centrosomes. This work provides the rationale and potential for the large-area assembly of microtubules and should expand the application of centrosomes and centrosome components for the creation of microtubule-based nanoscale devices.
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http://dx.doi.org/10.1166/jnn.2009.c043DOI Listing
February 2009

The small organic compound HMN-176 delays satisfaction of the spindle assembly checkpoint by inhibiting centrosome-dependent microtubule nucleation.

Mol Cancer Ther 2009 Mar 3;8(3):592-601. Epub 2009 Mar 3.

Department of Biology and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA.

HMN-176 is a potential new cancer therapeutic known to retard the proliferation of tumor cell lines. Here, we show that this compound inhibits meiotic spindle assembly in surf clam oocytes and delays satisfaction of the spindle assembly checkpoint in human somatic cells by inducing the formation of short and/or multipolar spindles. HMN-176 does not affect centrosome assembly, nuclear envelope breakdown, or other aspects of meiotic or mitotic progression, nor does it affect the kinetics of Spisula or mammalian microtubule (MT) assembly in vitro. Notably, HMN-176 inhibits the formation of centrosome-nucleated MTs (i.e., asters) in Spisula oocytes and oocyte extracts, as well as from isolated Spisula or mammalian centrosomes in vitro. Together, these results reveal that HMN-176 is a first-in-class anticentrosome drug that inhibits proliferation, at least in part, by disrupting centrosome-mediated MT assembly during mitosis.
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http://dx.doi.org/10.1158/1535-7163.MCT-08-0876DOI Listing
March 2009

BRCA1 regulates gamma-tubulin binding to centrosomes.

Cancer Biol Ther 2007 Dec 13;6(12):1853-7. Epub 2007 Oct 13.

Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Centrosomes are the cellular organelles that nucleate microtubules (MTs) via the activity of gamma-tubulin ring complex(s) (gammaTuRC) bound to the pericentriolar material of the centrosomes. BRCA1, the breast and ovarian cancer specific tumor suppressor, inhibits centrosomal MT nucleation via its ubiquitin ligase activity, and one of the known BRCA1 substrates is the key gammaTuRC component, gamma-tubulin. We analyzed the mechanism by which BRCA1 regulates centrosome function using an in vitro reconstitution assay, which includes separately staged steps. Our results are most consistent with a model by which the BRCA1 ubiquitin ligase modifies both gamma-tubulin plus a second centrosomal protein that controls localization of gammaTuRC to the centrosome. We suggest that this second protein is an adapter protein or protein complex that docks gamma-TuRC to the centrosome. By controlling gamma-TuRC localization, BRCA1 appropriately inhibits centrosome function, and loss of BRCA1 would result in centrosome hyperactivity, supernumerary centrosomes and, possibly, aneuploidy.
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http://dx.doi.org/10.4161/cbt.6.12.5164DOI Listing
December 2007

Aurora-A kinase regulates breast cancer associated gene 1 inhibition of centrosome-dependent microtubule nucleation.

Cancer Res 2007 Dec;67(23):11186-94

Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Breast cancer-associated gene 1 (BRCA1) regulates the duplication and the function of centrosomes in breast cells. We have previously shown that BRCA1 ubiquitin ligase activity directly inhibits centrosome-dependent microtubule nucleation. However, there is a paradox because centrosome microtubule nucleation potential is highest during mitosis, a phase when BRCA1 is most abundant at the centrosome. In this study, we resolve this conundrum by testing whether centrosomes from cells in M phase are regulated differently by BRCA1 when compared with other phases of the cell cycle. We observed that BRCA1-dependent inhibition of centrosome microtubule nucleation was high in S phase but was significantly lower during M phase. The cell cycle-specific effects of BRCA1 on centrosome-dependent microtubule nucleation were detected in living cells and in cell-free experiments using centrosomes purified from cells at specific stages of the cell cycle. We show that Aurora-A kinase modulates the BRCA1 inhibition of centrosome function by decreasing the E3 ubiquitin ligase activity of BRCA1. In addition, dephosphorylation of BRCA1 by protein phosphatase 1 alpha enhances the E3 ubiquitin ligase activity of BRCA1. These observations reveal that the inhibition of centrosome microtubule nucleation potential by the BRCA1 E3 ubiquitin ligase is controlled by Aurora-A kinase and protein phosphatase 1 alpha-mediated phosphoregulation through the different phases of the cell cycle.
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http://dx.doi.org/10.1158/0008-5472.CAN-07-2578DOI Listing
December 2007

Why funding cuts at the National Institutes of Health are so painful.

Physiologist 2007 Aug;50(4):129, 131-3

FASEB Office of Public Affairs, 9650 Rockville Pike, Bethesda, MD 20814, USA.

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August 2007

Laser intensity dependence of femtosecond near-infrared optoinjection.

Phys Rev E Stat Nonlin Soft Matter Phys 2007 Apr 3;75(4 Pt 1):041903. Epub 2007 Apr 3.

Department of Physics, Applied Physics & Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA.

We report an experimental study on transient membrane permeabilization of single living bovine aortic endothelial cells (BAEC) by tightly focused femtosecond near-infrared laser pulses. The membrane permeabilization of the BAEC cells was studied as a function of the incident laser intensity. The rate of dye uptake by the cells was analyzed using time-lapse imaging. We found that membrane permeabilization occurs for laser intensities higher than 4.0 x 10(12) W/cm(2). For laser intensity above 3.3 x 10(13) W/cm(2) the cell disintegrates. Within these two limits the rate of dye uptake increases logarithmically with increasing laser intensity. This functional dependence is explained by considering the Gaussian intensity distribution across the laser focal spot. Cell membrane permeabilization is explained by the creation of a plasma within the laser focal spot. The physical understanding of the relationship between dye uptake, pore characteristics, and laser intensity allows control of the concentrations of molecules delivered into cells through the control of pore characteristics.
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http://dx.doi.org/10.1103/PhysRevE.75.041903DOI Listing
April 2007

Cyclin E/Cdk2 is required for sperm maturation, but not DNA replication, in early sea urchin embryos.

Genesis 2007 May;45(5):282-91

Program in Molecular Biology and Biotechnology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.

The cell cycle is driven by the activity of cyclin/cdk complexes. In somatic cells, cyclin E/cdk2 oscillates throughout the cell cycle and has been shown to promote S-phase entry and initiation of DNA replication. In contrast, cyclin E/cdk2 activity remains constant throughout the early embryonic development of the sea urchin and localizes to the sperm nucleus following fertilization. We now show that cyclin E localization to the sperm nucleus following fertilization is not unique to the sea urchin, but also occurs in the surf clam, and inhibition of cyclin E/cdk2 activity by roscovitine inhibits the morphological changes indicative of male pronuclear maturation in sea urchin zygotes. Finally, we show that inhibition of cyclin E/cdk2 activity does not block DNA replication in the early cleavage cycles of the sea urchin. We conclude that cyclin E/cdk2 activity is required for male pronuclear maturation, but not for initiation of DNA replication in early sea urchin development.
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http://dx.doi.org/10.1002/dvg.20291DOI Listing
May 2007

What's happening to the new investigator?

FASEB J 2006 Jul;20(9):1288-9

Federation of American Societies for Experimental Biology, Bethesda, Maryland, USA.

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http://dx.doi.org/10.1096/fj.06-0704ufmDOI Listing
July 2006

Centrosome-associated RNA in surf clam oocytes.

Proc Natl Acad Sci U S A 2006 Jun 5;103(24):9034-8. Epub 2006 Jun 5.

Department of Cell Biology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.

Centrosomes are the major microtubule-organizing center in animal cells. They are composed of a pair of [9(3) + 0] centrioles surrounded by a relatively ill-defined pericentriolar matrix, provide the ciliary centriole-kinetosome (basal body) progenitor, and organize the assembly of microtubules into the mitotic spindle during cell division. Despite >100 years of microscopic observation and their obvious significance, our understanding of centrosome composition, dynamic organization, and mechanism of action is limited when compared with that of other cellular organelles. Centrosomes duplicate only once per cell cycle to ensure development of a normal bipolar spindle. The initial event in centrosome duplication is centriole replication, which is generative, semiconservative, and independent of the nucleus. Such observations led to the proposal that centrosomes contain their own complement of nucleic acids, possibly representative of an organellar genome comparable with those described for mitochondria and chloroplasts. The consensus in the field is that centrosomes lack DNA but may contain RNA. We isolated centrosomes from oocytes of the surf clam, Spisula solidissima, and purified from them a unique set of RNAs. We show here by biochemical means and subcellular in situ hybridization that the first transcript we analyzed is intimately associated with centrosomes. Sequence analysis reveals that this centrosome-associated RNA encodes a conserved RNA-directed polymerase domain. The hypothesis that centrosomes contain an intrinsic complement of specific RNAs suggests new opportunities to address the century-old problem of centrosome function, heredity, and evolution.
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http://dx.doi.org/10.1073/pnas.0602859103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1482561PMC
June 2006

Direct patterning of centrosome arrays as templates for the assembly of microtubules.

Biotechnol Bioeng 2006 Aug;94(5):1012-6

Rensselaer Nanotechnology Center, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180-3950, USA.

We have achieved, for the first time, the selective patterning of centrosomes onto solid substrates. The use of such patterned centrosome arrays as templates for the directed polymerization of microtubules was also demonstrated. Centrosomes are small organelles in animal cells that serve as nucleation and organization centers of microtubules. Directed assembly of microtubules on the patterned centrosome arrays provides a new route to control the positions and directions of microtubules on surfaces. Combining the patterning of the isolated centrosomes and the directed growth of microtubules may lead to the generation of desired microtubule networks for bio-based nanodevices.
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http://dx.doi.org/10.1002/bit.20846DOI Listing
August 2006

Warming up at the poles.

EMBO Rep 2006 Apr 24;7(4):364-71. Epub 2006 Mar 24.

Paterson Institute for Cancer Research, Wilmslow Road, Manchester, UK.

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http://dx.doi.org/10.1038/sj.embor.7400660DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1456901PMC
April 2006

Spontaneous right ventricular disruption following treatment of sternal infection.

J Card Surg 2004 Jan-Feb;19(1):74-8

Department of Cardiothoracic Surgery, Long Island Jewish Medical Center, Albert Einstein College of Medicine, New Hyde Park, New York 11040, USA.

Background: Spontaneous right ventricular disruption is a rare and frequently catastrophic event that occurs during the treatment of mediastinitis complicating median sternotomy wound.

Objective: The purpose of this study is to understand the pathogenesis of the spontaneous right ventricular disruption and to suggest strategies for the prevention and treatment of this rare but potentially fatal complication of cardiac surgery.

Methods: We report three cases as an introduction to the review of 39 cases found in the English-language literature.

Results: The majority of patients (71%) underwent coronary artery bypass grafting as the primary procedure prior to the development of a sternal infection. Staphylococcus Aureus and Staphylococcus Epidermidis were cultured most frequently from the sternal wound (31% and 24%, respectively). The mean interval between sternal debridement and the right ventricular disruption was 2.9 days. Most patients (24 of 42) required cardiopulmonary bypass for the repair of the right ventricular disruption. Biologic patches and adjuncts were used in 15 patients (36%). Eight patients (19%) died either preoperatively or on the operating-room table.

Conclusions: Spontaneous right ventricular disruption is a potentially preventable complication. To prevent this complication we recommend: (1) avoidance of delay between diagnosis and operative treatment of mediastinitis; (2) complete lysis of adhesions between the posterior sternal edge and anterior surface of the right ventricle under general anesthesia with heart-lung machine stand-by; (3) repair of the right ventricular tear using biologic patches with heart-lung machine stand-by; (4) early (if possible immediate) closure of the chest with a myocutaneous flap.
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http://dx.doi.org/10.1111/j.0886-0440.2004.04015.xDOI Listing
June 2004

Rapid tau aggregation and delayed hippocampal neuronal death induced by persistent thrombin signaling.

J Biol Chem 2003 Sep 23;278(39):37681-9. Epub 2003 Jun 23.

Neurobiology Research Laboratory, Veterans Affairs Medical Center, Kansas City, Missouri 64128, USA.

Tau hyperphosphorylation, leading to self-aggregation, is widely held to underlie the neurofibrillary degeneration found in Alzheimer's disease (AD) and other tauopathies. However, it is unclear exactly what environmental factors may trigger this pathogenetic tau hyperphosphorylation. From several perspectives, the coagulation serine protease, thrombin, has been implicated in AD and activates several different protein kinase pathways but has not previously been shown how it may contribute to AD pathogenesis. Here we report that nanomolar thrombin induced rapid tau hyperphosphorylation and aggregation in murine hippocampal neurons via protease-activated receptors, which was followed by delayed synaptophysin reduction and apoptotic neuronal death. Mechanistic study revealed that a persistent thrombin signaling via protease-activated receptor 4 and prolonged downstream p44/42 mitogenactivated protein kinase activation are at least in part responsible. These results pathogenetically linked thrombin to subpopulations of AD and other tauopathies associated with cerebrovascular damage. Such knowledge may be instrumental in transforming therapeutic paradigms.
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http://dx.doi.org/10.1074/jbc.M301406200DOI Listing
September 2003

Effect of gamma-synuclein overexpression on matrix metalloproteinases in retinoblastoma Y79 cells.

Arch Biochem Biophys 2003 Feb;410(1):167-76

Department of Molecular Biosciences, Kansas University, 4004 Haworth Hall, Lawrence, KS 66045, USA.

gamma-Synuclein is a small cytoplasmic protein implicated in neurodegenerative diseases and cancer. However, the mechanism of its involvement in diseases is not clear. We studied the role of gamma-synuclein in the regulation of matrix metalloproteinases in retinoblastoma cell culture. Matrix metalloproteinases play important roles in the remodeling of extracellular matrix implicated in tumor progression and in the neurodegenerative diseases. Western blot and zymography data demonstrated a moderate elevation of matrix metalloproteinases-2 and significant upregulation of matrix metalloproteinases-9 in stable cell lines overexpressing gamma-synuclein. No effect of gamma-synuclein overexpression on matrix metalloproteinases-1 level or activity was found. Chloramphenicol-acetyltransferase assay demonstrated that overexpression of gamma-synuclein increases the efficiency of the matrix metalloproteinases-9 promoter. This increment of promoter activity may be mediated by the AP-1 binding site(s), since point mutations in one of these sites (Pr18 or Pr19) and elimination of the distal AP-1 site (Pr14) reduced the increment of promoter activity.
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http://dx.doi.org/10.1016/s0003-9861(02)00664-1DOI Listing
February 2003

Characterization of Cep135, a novel coiled-coil centrosomal protein involved in microtubule organization in mammalian cells.

J Cell Biol 2002 Jan 7;156(1):87-99. Epub 2002 Jan 7.

Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.

By using monoclonal antibodies raised against isolated clam centrosomes, we have identified a novel 135-kD centrosomal protein (Cep135), present in a wide range of organisms. Cep135 is located at the centrosome throughout the cell cycle, and localization is independent of the microtubule network. It distributes throughout the centrosomal area in association with the electron-dense material surrounding centrioles. Sequence analysis of cDNA isolated from CHO cells predicted a protein of 1,145-amino acid residues with extensive alpha-helical domains. Expression of a series of deletion constructs revealed the presence of three independent centrosome-targeting domains. Overexpression of Cep135 resulted in the accumulation of unique whorl-like particles in both the centrosome and the cytoplasm. Although their size, shape, and number varied according to the level of protein expression, these whorls were composed of parallel dense lines arranged in a 6-nm space. Altered levels of Cep135 by protein overexpression and/or suppression of endogenous Cep135 by RNA interference caused disorganization of interphase and mitotic spindle microtubules. Thus, Cep135 may play an important role in the centrosomal function of organizing microtubules in mammalian cells.
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http://dx.doi.org/10.1083/jcb.200108088DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2173569PMC
January 2002
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