scholarly journals Loss of Awareness or Urinary Dysfunction? Investigating Amyloidosis and Urinary Physiology in a Transgenic Mouse

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 533-533
Author(s):  
Cara Hardy ◽  
Ramalakshmi Ramasamy ◽  
Dawn Rosenberg ◽  
Philip Scarpa ◽  
Xiangyou Hu ◽  
...  
Keyword(s):  
Transgenic Animals ◽  
Field Testing ◽  
Tissue Level ◽  
Urinary Dysfunction ◽  
Adrenergic Stimulation ◽  
Urinary Function ◽  
Cortical Function ◽  
Plaque Deposition ◽  
And Function ◽  
Behavioral Assays

Abstract Alzheimer’s disease (AD) is a devastating disorder primarily affecting older adults and is the most common neurodegenerative disease in the US. More than one in three AD patients experience AD-associated urinary dysfunction (ADUD), which directly contributes to their institutionalization. While ADUD has been clinically regarded as a result of poor cognitive control over urinary function, the physiology underlying loss of urinary control remains unknown. We hypothesize that amyloidosis in the CNS results in pathologic changes in urinary structure and function. Tg-APP/PS1DE9 mice were used before plaque deposition (4-6 months) and after plaque accumulation (8-10 months) and compared to WT littermates. Behavioral assays (open field testing and voiding spot assays) were performed to assess cortical function. Pressure-flow cystometry was conducted under urethane anesthesia to assess autonomic control of urinary function without cortical influence. Pharmacomyography of bladder strips was used to determine tissue-level changes in the absence of CNS input. In Tg-APP/PS1DE9 mice, plaque accumulation resulted in significant cystometric changes to voiding phase parameters, but not storage phase parameters. Pharmacologic studies showed decreased sensitivity to adrenergic stimulation without change in muscarinic sensitivity. Behavioral assays demonstrated significant differences between transgenic animals and WT in locomotion and voiding spot sizes. We interpret our data to support AD-related pathology of Aβ accumulation results in a distinct urinary phenotype in our model, analogous to the ADUD observed in AD patients. Establishing and verifying models of ADUD may improve the efficacy of treating ADUD and increase quality of life for patients and their caregivers.

scholarly journals Alzheimer’s Disease-Associated Pathology in a Transgenic Mouse Model Results in Altered Voiding Function

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 117-117
Author(s):  
Cara Hardy ◽  
Dawn Rosenberg ◽  
Ramalakshmi Ramasamy ◽  
Xiangyou Hu ◽  
Phillip Smith
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Tissue Level ◽  
Voiding Function ◽  
Plaque Deposition ◽  
Cholinergic Signaling ◽  
Volume Sensitivity ◽  
The Us ◽  
And Function ◽  
Patients Experience

Abstract Alzheimer’s disease (AD) is a devastating disorder primarily affecting older adults and is the most common neurodegenerative disease in the US. More than one in three AD patients experience AD-associated urinary dysfunction (ADUD), which directly contributes to their institutionalization. While ADUD has been clinically regarded as a result of poor cognitive control over urinary function, the physiology underlying loss of urinary control remains unknown. We hypothesize that beta-amyloidosis in the CNS results in pathologic changes in urinary structure and function. Male and female Tg-APP/PS1DE9 mice were used before plaque deposition (4-6 months) and after plaque accumulation (8-10 months) and compared to their WT littermates. Pressure-flow cystometry was conducted under urethane anesthesia to assess urinary performance at the level of the autonomic nervous system in the absence of cortical control. Pharmacomyography was performed on bladder strips to determine tissue-level changes in the absence of CNS input. In Tg-APP/PS1DE9 mice, plaque accumulation resulted in diminished volume sensitivity and decreased voiding efficiency. Pharmacologic studies showed aberrant drug responses, altered cholinergic signaling, and decreased resilience of tissue longevity after plaque accumulation. Based on our findings, we conclude that the AD-related pathology of Aβ accumulation results in a distinct urinary phenotype in our model, analogous to the ADUD observed in AD patients. Establishing and expanding models of ADUD to other mouse models of AD-associated pathology may improve the efficacy of treating ADUD and increase quality of life for patients and their caregivers.

scholarly journals Multiphoton Imaging of Ca2+ Instability in Acute Myocardial Slices from a RyR2R2474S Murine Model of Catecholaminergic Polymorphic Ventricular Tachycardia

2021 ◽  
Vol 10 (13) ◽  
pp. 2821
Author(s):  
Giulia Borile ◽  
Tania Zaglia ◽  
Stephan E. Lehnart ◽  
Marco Mongillo
Keyword(s):  
Ventricular Tachycardia ◽  
Single Cells ◽  
Tissue Level ◽  
Catecholaminergic Polymorphic Ventricular Tachycardia ◽  
Polymorphic Ventricular Tachycardia ◽  
Adrenergic Stimulation ◽  
Release Channel ◽  
Multiphoton Imaging ◽  
Delayed Afterdepolarizations ◽  
Multiple Cells

Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is a familial stress-induced arrhythmia syndrome, mostly caused by mutations in Ryanodine receptor 2 (RyR2), the sarcoplasmic reticulum (SR) Ca2+ release channel in cardiomyocytes. Pathogenetic mutations lead to gain of function in the channel, causing arrhythmias by promoting diastolic spontaneous Ca2+ release (SCR) from the SR and delayed afterdepolarizations. While the study of Ca2+ dynamics in single cells from murine CPVT models has increased our understanding of the disease pathogenesis, questions remain on the mechanisms triggering the lethal arrhythmias at tissue level. Here, we combined subcellular analysis of Ca2+ signals in isolated cardiomyocytes and in acute thick ventricular slices of RyR2R2474S knock-in mice, electrically paced at different rates (1–5 Hz), to identify arrhythmogenic Ca2+ dynamics, from the sub- to the multicellular perspective. In both models, RyR2R2474S cardiomyocytes had increased propensity to develop SCR upon adrenergic stimulation, which manifested, in the slices, with Ca2+ alternans and synchronous Ca2+ release events in neighboring cardiomyocytes. Analysis of Ca2+ dynamics in multiple cells in the tissue suggests that SCRs beget SCRs in contiguous cells, overcoming the protective electrotonic myocardial coupling, and potentially generating arrhythmia triggering foci. We suggest that intercellular interactions may underscore arrhythmic propensity in CPVT hearts with ‘leaky’ RyR2.

scholarly journals Spontaneous calcium release in tissue from the failing canine heart

2009 ◽  
Vol 297 (4) ◽  
pp. H1235-H1242 ◽  
Author(s):  
Gregory S. Hoeker ◽  
Rodolphe P. Katra ◽  
Lance D. Wilson ◽  
Bradley N. Plummer ◽  
Kenneth R. Laurita
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Tissue Level ◽  
Calcium Handling ◽  
Canine Heart ◽  
Myocardial Cells ◽  
Spontaneous Release ◽  
Adrenergic Stimulation ◽  
Electrical Instability ◽  
Delayed Afterdepolarization

Abnormalities in calcium handling have been implicated as a significant source of electrical instability in heart failure (HF). While these abnormalities have been investigated extensively in isolated myocytes, how they manifest at the tissue level and trigger arrhythmias is not clear. We hypothesize that in HF, triggered activity (TA) is due to spontaneous calcium release from the sarcoplasmic reticulum that occurs in an aggregate of myocardial cells (an SRC) and that peak SCR amplitude is what determines whether TA will occur. Calcium and voltage optical mapping was performed in ventricular wedge preparations from canines with and without tachycardia-induced HF. In HF, steady-state calcium transients have reduced amplitude [135 vs. 170 ratiometric units (RU), P < 0.05] and increased duration (252 vs. 229 s, P < 0.05) compared with those of normal. Under control conditions and during β-adrenergic stimulation, TA was more frequent in HF (53% and 93%, respectively) compared with normal (0% and 55%, respectively, P < 0.025). The mechanism of arrhythmias was SCRs, leading to delayed afterdepolarization-mediated triggered beats. Interestingly, the rate of SCR rise was greater for events that triggered a beat (0.41 RU/ms) compared with those that did not (0.18 RU/ms, P < 0.001). In contrast, there was no difference in SCR amplitude between the two groups. In conclusion, TA in HF tissue is associated with abnormal calcium regulation and mediated by the spontaneous release of calcium from the sarcoplasmic reticulum in aggregates of myocardial cells (i.e., an SCR), but importantly, it is the rate of SCR rise rather than amplitude that was associated with TA.

scholarly journals MITO-Tag Mice enable rapid isolation and multimodal profiling of mitochondria from specific cell types in vivo

2018 ◽  
Vol 116 (1) ◽  
pp. 303-312 ◽  
Author(s):  
Erol C. Bayraktar ◽  
Lou Baudrier ◽  
Ceren Özerdem ◽  
Caroline A. Lewis ◽  
Sze Ham Chan ◽  
...  
Keyword(s):  
Metabolite Profiling ◽  
Cultured Cells ◽  
Transgenic Animals ◽  
Cell Types ◽  
Tissue Level ◽  
Specific Cell ◽  
Mammalian Tissues ◽  
Cell Type Specific ◽  
Untargeted Metabolite Profiling

Mitochondria are metabolic organelles that are essential for mammalian life, but the dynamics of mitochondrial metabolism within mammalian tissues in vivo remains incompletely understood. While whole-tissue metabolite profiling has been useful for studying metabolism in vivo, such an approach lacks resolution at the cellular and subcellular level. In vivo methods for interrogating organellar metabolites in specific cell types within mammalian tissues have been limited. To address this, we built on prior work in which we exploited a mitochondrially localized 3XHA epitope tag (MITO-Tag) for the fast isolation of mitochondria from cultured cells to generate MITO-Tag Mice. Affording spatiotemporal control over MITO-Tag expression, these transgenic animals enable the rapid, cell-type-specific immunoisolation of mitochondria from tissues, which we verified using a combination of proteomic and metabolomic approaches. Using MITO-Tag Mice and targeted and untargeted metabolite profiling, we identified changes during fasted and refed conditions in a diverse array of mitochondrial metabolites in hepatocytes and found metabolites that behaved differently at the mitochondrial versus whole-tissue level. MITO-Tag Mice should have utility for studying mitochondrial physiology, and our strategy should be generally applicable for studying other mammalian organelles in specific cell types in vivo.

scholarly journals MITO-Tag Mice enable rapid isolation and multimodal profiling of mitochondria from specific cell types in vivo

2018 ◽  
Author(s):  
Erol Can Bayraktar ◽  
Lou Baudrier ◽  
Ceren Özerdem ◽  
Caroline A. Lewis ◽  
Sze Ham Chan ◽  
...  
Keyword(s):  
Metabolite Profiling ◽  
Cultured Cells ◽  
Transgenic Animals ◽  
Cell Types ◽  
Tissue Level ◽  
Specific Cell ◽  
Mammalian Tissues ◽  
Cell Type Specific ◽  
Untargeted Metabolite Profiling

ABSTRACTMitochondria are metabolic organelles that are essential for mammalian life, but the dynamics of mitochondrial metabolism within mammalian tissues in vivo remains incompletely understood. While whole-tissue metabolite profiling has been useful for studying metabolism in vivo, such an approach lacks resolution at the cellular and subcellular level. In vivo methods for interrogating organellar metabolites in specific cell-types within mammalian tissues have been limited. To address this, we built on prior work in which we exploited a mitochondrially-localized 3XHA epitope-tag (“MITO-Tag”) for the fast isolation of mitochondria from cultured cells to now generate “MITO-Tag Mice.” Affording spatiotemporal control over MITO-Tag expression, these transgenic animals enable the rapid, cell-type-specific immunoisolation of mitochondria from tissues, which we verified using a combination of proteomic and metabolomic approaches. Using MITO-Tag Mice and targeted and untargeted metabolite profiling, we identified changes during fasted and refed conditions in a diverse array of mitochondrial metabolites in hepatocytes and found metabolites that behaved differently at the mitochondrial versus whole-tissue level. MITO-Tag Mice should have utility for studying mitochondrial physiology and our strategy should be generally applicable for studying other mammalian organelles in specific cell-types in vivo.

scholarly journals Role of type 2A phosphatase regulatory subunit B56α in regulating cardiac responses to β-adrenergic stimulation in vivo

2018 ◽  
Vol 115 (3) ◽  
pp. 519-529 ◽  
Author(s):  
Sarah-Lena Puhl ◽  
Kate L Weeks ◽  
Alican Güran ◽  
Antonella Ranieri ◽  
Peter Boknik ◽  
...  
Keyword(s):  
Systolic Dysfunction ◽  
Heart Tissue ◽  
Left Ventricular ◽  
Regulatory Subunit ◽  
Adrenergic Stimulation ◽  
Hypertrophic Response ◽  
Cardiac Responses ◽  
Cardiac Phenotype ◽  
And Function

Abstract Aims B56α is a protein phosphatase 2A (PP2A) regulatory subunit that is highly expressed in the heart. We previously reported that cardiomyocyte B56α localizes to myofilaments under resting conditions and translocates to the cytosol in response to acute β-adrenergic receptor (β-AR) stimulation. Given the importance of reversible protein phosphorylation in modulating cardiac function during sympathetic stimulation, we hypothesized that loss of B56α in mice with targeted disruption of the gene encoding B56α (Ppp2r5a) would impact on cardiac responses to β-AR stimulation in vivo. Methods and results Cardiac phenotype of mice heterozygous (HET) or homozygous (HOM) for the disrupted Ppp2r5a allele and wild type (WT) littermates was characterized under basal conditions and following acute β-AR stimulation with dobutamine (DOB; 0.75 mg/kg i.p.) or sustained β-AR stimulation by 2-week infusion of isoproterenol (ISO; 30 mg/kg/day s.c.). Left ventricular (LV) wall thicknesses, chamber dimensions and function were assessed by echocardiography, and heart tissue collected for gravimetric, histological, and biochemical analyses. Western blot analysis revealed partial and complete loss of B56α protein in hearts from HET and HOM mice, respectively, and no changes in the expression of other PP2A regulatory, catalytic or scaffolding subunits. PP2A catalytic activity was reduced in hearts of both HET and HOM mice. There were no differences in the basal cardiac phenotype between genotypes. Acute DOB stimulation induced the expected inotropic response in WT and HET mice, which was attenuated in HOM mice. In contrast, DOB-induced increases in heart rate were unaffected by B56α deficiency. In WT mice, ISO infusion increased LV wall thicknesses, cardiomyocyte area and ventricular mass, without LV dilation, systolic dysfunction, collagen deposition or foetal gene expression. The hypertrophic response to ISO was blunted in mice deficient for B56α. Conclusion These findings identify B56α as a potential regulator of cardiac structure and function during β-AR stimulation.

Intense exercise causes decrease in expression of both endothelial NO synthase and tissue NOx level in hearts

2000 ◽  
Vol 279 (3) ◽  
pp. R951-R959 ◽  
Author(s):  
Motoyuki Iemitsu ◽  
Takashi Miyauchi ◽  
Seiji Maeda ◽  
Koichi Yuki ◽  
Tsutomu Kobayashi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Heart Rate ◽  
Mrna Level ◽  
Tissue Level ◽  
No Synthase ◽  
Adrenergic Stimulation ◽  
Intense Exercise ◽  
End Products ◽  
First Time ◽  
Enos Protein

Cardiac myocytes produce nitric oxide (NO). We studied the effects of intense exercise on the expression of NO synthase (NOS) and the tissue level of nitrite (NO2 −)/nitrate (NO3 −) (i.e., NOx), which are stable end products of NO in the heart. Rats ran on a treadmill for 45 min. Immediately after this exercise, the heart was quickly removed. Control rats remained at rest during the same 45-min period. The mRNA level of endothelial NOS (eNOS) in the heart was markedly lower in the exercised rats than in the control rats. Western blot analysis confirmed downregulation of eNOS protein in the heart after exercise. Tissue NOx level in the heart was significantly lower in the exercised rats than in the control rats. The present study revealed for the first time that production of NO in the heart is decreased by intense exercise. Because NO attenuates positive inotropic and chronotropic responses to β1-adrenergic stimulation in the heart, the decrease in cardiac production of NO by intense exercise may contribute to the acceleration of increase in myocardial contractility and heart rate during intense exercise.

Left ventricular function during lethal and sublethal endotoxemia in swine

1986 ◽  
Vol 251 (2) ◽  
pp. H364-H373 ◽  
Author(s):  
R. D. Goldfarb ◽  
L. M. Nightingale ◽  
P. Kish ◽  
P. B. Weber ◽  
D. J. Loegering
Keyword(s):  
Low Dose ◽  
Diastolic Pressure ◽  
Contractile Function ◽  
Lethal Dose ◽  
Cardiac Contractility ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
High Dose ◽  
Adrenergic Stimulation ◽  
And Function

Our previous studies suggested that after a median lethal dose (LD50) of endotoxin, cardiac contractility was depressed in nonsurviving dogs. The canine cardiovascular system is unlike humans in that dogs have a hepatic vein sphincter that is susceptible to adrenergic stimulation capable of raising hepatic and splanchnic venous pressures. We retested the hypothesis that lethality after endotoxin administration is associated with cardiac contractile depression in pigs, because the hepatic circulation in this species is similar to that of humans. We compared cardiac mechanical function of pigs administered a high dose (250 micrograms/kg) or a low dose (100 micrograms/kg) endotoxin by use of the slope of the end-systolic pressure-diameter relationship (ESPDR) as well as other measurements of cardiac performance. In all the pigs administered a high dose, ESPDR demonstrated a marked, time-dependent depression, whereas we observed no significant ESPDR changes after low endotoxin doses. The other cardiodynamic variables were uninterpretable, due to the significant changes in heart rate, end-diastolic diameter (preload), and aortic diastolic pressure (afterload). Plasma myocardial depressant factor activity accumulated in all endotoxin-administered animals, tending to be greater in the high-dose group. In this group, both subendocardial blood flow and global function were depressed, whereas pigs administered the low dose of endotoxin demonstrated slight, but nonsignificant, increases in flow and function. These observations indicate that myocardial contractile depression is associated with a lethal outcome to high doses of endotoxin. One possible mechanism for this loss of contractile function may be a relative hypoperfusion of the subendocardium.

scholarly journals Vessel-on-a-chip models for studying microvascular physiology, transport, and function in vitro

2020 ◽  
Author(s):  
Savannah R. Moses ◽  
Jonathan J. Adorno ◽  
Andre F. Palmer ◽  
Jonathan W. Song
Keyword(s):  
Cell Culture ◽  
Tissue Level ◽  
Culture Conditions ◽  
Cell Culture Techniques ◽  
Culture Techniques ◽  
Microscale Flow ◽  
Flow Phenomena ◽  
Defined Culture ◽  
And Function

To understand how the microvasculature grows and remodels, researchers require reproducible systems that emulate the function of living tissue. Innovative contributions toward fulfilling this important need have been made by engineered microvessels assembled in vitro using microfabrication techniques. Microfabricated vessels, commonly referred to as "vessels on a chip," are from a class of cell culture technologies that uniquely integrate microscale flow phenomena, tissue-level biomolecular transport, cell-cell interactions, and proper 3-D extracellular matrix environments under well-defined culture conditions. Here, we discuss the enabling attributes of microfabricated vessels that make these models more physiological compared to established cell culture techniques, and the potential of these models for advancing microvascular research. This review highlights the key features of microvascular transport and physiology, critically discusses the strengths and limitations of different microfabrication strategies for studying the microvasculature, and provides a perspective on current challenges and future opportunities for vessel on a chip models.

Characterization of the mononuclear phagocyte system in zebrafish

Blood ◽  
2011 ◽  
Vol 117 (26) ◽  
pp. 7126-7135 ◽  
Author(s):  
Valerie Wittamer ◽  
Julien Y. Bertrand ◽  
Patrick W. Gutschow ◽  
David Traver
Keyword(s):  
Fluorescent Protein ◽  
Transgenic Animals ◽  
Regulatory Elements ◽  
Mononuclear Phagocyte ◽  
Mononuclear Phagocytes ◽  
Reporter Line ◽  
Transgenic Lines ◽  
Green Fluorescent ◽  
And Function ◽  
Antigen Presenting

Abstract The evolutionarily conserved immune system of the zebrafish (Danio rerio), in combination with its genetic tractability, position it as an excellent model system in which to elucidate the origin and function of vertebrate immune cells. We recently reported the existence of antigen-presenting mononuclear phagocytes in zebrafish, namely macrophages and dendritic cells (DCs), but have been impaired in further characterizing the biology of these cells by the lack of a specific transgenic reporter line. Using regulatory elements of a class II major histocompatibility gene, we generated a zebrafish reporter line expressing green fluorescent protein (GFP) in all APCs, macrophages, DCs, and B lymphocytes. Examination of mhc2dab:GFP; cd45:DsRed double-transgenic animals demonstrated that kidney mhc2dab:GFPhi; cd45:DsRedhi cells were exclusively mature monocytes/macrophages and DCs, as revealed by morphologic and molecular analyses. Mononuclear phagocytes were found in all hematolymphoid organs, but were most abundant in the intestine and spleen, where they up-regulate the expression of inflammatory cytokines upon bacterial challenge. Finally, mhc2dab:GFP and cd45:DsRed transgenes mark mutually exclusive cell subsets in the lymphoid fraction, enabling the delineation of the major hematopoietic lineages in the adult zebrafish. These findings suggest that mhc2dab:GFP and cd45:DsRed transgenic lines will be instrumental in elucidating the immune response in the zebrafish.

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