scholarly journals Retinal Inflammation, Oxidative Stress, and Vascular Impairment Is Ablated in Diabetic Mice Receiving XMD8-92 Treatment

2021 ◽  
Vol 12 ◽  
Author(s):  
Scott J. Howell ◽  
Chieh A. Lee ◽  
Julia C. Batoki ◽  
Thomas E. Zapadka ◽  
Sarah I. Lindstrom ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Diabetic Retinopathy ◽  
New Drugs ◽  
Type I ◽  
Type Ii ◽  
Diabetic Mice ◽  
Junction Protein ◽  
Type Ii Diabetics ◽  
Retinal Inflammation

The global number of diabetics continues to rise annually. As diabetes progresses, almost all of Type I and more than half of Type II diabetics develop diabetic retinopathy. Diabetic retinopathy is a microvascular disease of the retina, and is the leading cause of blindness in the working-age population worldwide. With such a significant health impact, new drugs are required to halt the blinding threat posed by this visual disorder. The cause of diabetic retinopathy is multifactorial, and an optimal therapeutic would halt inflammation, cease photoreceptor cell dysfunction, and ablate vascular impairment. XMD8-92 is a small molecule inhibitor that blocks inflammatory activity downstream of ERK5 (extracellular signal-related kinase 5) and BRD4 (bromodomain 4). ERK5 elicits inflammation, is increased in Type II diabetics, and plays a pathologic role in diabetic nephropathy, while BRD4 induces retinal inflammation and plays a role in retinal degeneration. Further, we provide evidence that suggests both pERK5 and BRD4 expression are increased in the retinas of our STZ (streptozotocin)-induced diabetic mice. Taken together, we hypothesized that XMD8-92 would be a good therapeutic candidate for diabetic retinopathy, and tested XMD8-92 in a murine model of diabetic retinopathy. In the current study, we developed an in vivo treatment regimen by administering one 100 μL subcutaneous injection of saline containing 20 μM of XMD8-92 weekly, to STZ-induced diabetic mice. XMD8-92 treatments significantly decreased diabetes-mediated retinal inflammation, VEGF production, and oxidative stress. Further, XMD8-92 halted the degradation of ZO-1 (zonula occludens-1), which is a tight junction protein associated with vascular permeability in the retina. Finally, XMD8-92 treatment ablated diabetes-mediated vascular leakage and capillary degeneration, which are the clinical hallmarks of non-proliferative diabetic retinopathy. Taken together, this study provides strong evidence that XMD8-92 could be a potentially novel therapeutic for diabetic retinopathy.

scholarly journals Development of stabilized dual growth factor-loaded hyaluronate collagen dressing matrix

2021 ◽  
Vol 12 ◽  
pp. 204173142199975
Author(s):  
Jihyun Kim ◽  
Kyoung-Mi Lee ◽  
Seung Hwan Han ◽  
Eun Ae Ko ◽  
Dong Suk Yoon ◽  
...  
Keyword(s):  
Wound Healing ◽  
Growth Factor ◽  
Type I ◽  
Diabetic Mice ◽  
Patients With Diabetes ◽  
Diabetic Wound Healing ◽  
Epidermal Growth ◽  
Wound Healing Effect ◽  
Growth Factor Production

Patients with diabetes experience impaired growth factor production such as epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), and they are reportedly involved in wound healing processes. Here, we report dual growth factor-loaded hyaluronate collagen dressing (Dual-HCD) matrix, using different ratios of the concentration of stabilized growth factors—stabilized-EGF (S-EGF) and stabilized-bFGF (S-bFGF). At first, the optimal concentration ratio of S-EGF to S-bFGF in the Dual-HCD matrix is determined to be 1:2 in type I diabetic mice. This Dual-HCD matrix does not cause cytotoxicity and can be used in vivo. The wound-healing effect of this matrix is confirmed in type II diabetic mice. Dual HCD enhances angiogenesis which promotes wound healing and thus, it shows a significantly greater synergistic effect than the HCD matrix loaded with a single growth factor. Overall, we conclude that the Dual-HCD matrix represents an effective therapeutic agent for impaired diabetic wound healing.

A delayed rectifier conductance in type I hair cells of the mouse utricle

1996 ◽  
Vol 76 (2) ◽  
pp. 995-1004 ◽  
Author(s):  
A. Rusch ◽  
R. A. Eatock
Keyword(s):  
Hair Cells ◽  
Time Course ◽  
Dissociation Constants ◽  
Resting Potential ◽  
Delayed Rectifier ◽  
Type I ◽  
Type Ii ◽  
Voltage Range ◽  
Average Maximum

1. Membrane currents of hair cells in acutely excised or cultured mouse utricles were recorded with the whole cell voltage-clamp method at temperatures between 23 and 36 degrees C. 2. Type I and II hair cells both had delayed rectifier conductances that activated positive to -55 mV. 3. Type I, but not type II, hair cells had an additional delayed rectifier conductance (gK,L) with an activation range that was unusually negative and variable. At 23-25 degrees C, V(1/2) values ranged from -88 to -62 mV in 57 cells. 4. gK,L was very large. At 23-25 degrees C, the average maximum chord conductance was 75 +/- 65 nS (mean +/- SD, n = 57; measured at -54 mV), or approximately 21 nS/pF of cell capacitance. 5. gK,L was highly selective for K+ over Na+ (permeability ratio PNa+/PK+:0.006), but unlike other delayed rectifiers, gK,L was significantly permeable to Cs+ (PCs+/PK+:0.31). gK,L was independent of extracellular Ca2+. 6. At -64 mV, Ba2+ and 4-aminopyridine blocked gK,L with apparent dissociation constants of 2.0 mM and 43 microM, respectively. Extracellular Cs+ (5 mM) blocked gK,L by 50% at -124 mV. Apamin (100 nM) and dendrotoxin (10 nM) has no effect. 7. The kinetic data of gK,L are consistent with a sequential gating model with at least two closed states and one open state. The slow activation kinetics (principal time constants at 23-25 degrees C:600-200 ms) had a thermal Q10 of 2.1. Inactivation (Q10:2.7) was partial at all temperatures. Deactivation followed a double-exponential time course and had a Q10 of 2.0. 8. At 23-25 degrees C, gK,L was appreciably activated at the mean resting potential of type I hair cells (-77 +/- 3.1 mV, n = 62), so that input conductances were often more than an order of magnitude larger than those of type II cells. If these conditions hold in vivo, type I cells would produce unusually small receptor potentials. Warming the cells to 36 degrees C produced parallel shifts in gK,L's activation range (0.8 +/- 0.3 mV/degrees C, n = 8), and in the resting potential (0.6 +/- 0.3 mV/degrees C, n = 4). Thus the high input conductances were not an artifact of unphysiological temperatures but remained high near body temperature. It remains possible that in vivo gK,L's activation range is less negative and input conductances are lower; the large variance in the voltage range of activation suggests that it may be subject to modulation.

scholarly journals Biological Relevance of Colony Morphology and Phenotypic Switching by Burkholderia pseudomallei

2006 ◽  
Vol 189 (3) ◽  
pp. 807-817 ◽  
Author(s):  
Narisara Chantratita ◽  
Vanaporn Wuthiekanun ◽  
Khaemaporn Boonbumrung ◽  
Rachaneeporn Tiyawisutsri ◽  
Mongkol Vesaratchavest ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Vaccine Development ◽  
Colony Morphology ◽  
Phenotypic Switching ◽  
Type I ◽  
Type Ii ◽  
Altered Expression ◽  
Replication Fitness

ABSTRACT Melioidosis is a notoriously protracted illness and is difficult to cure. We hypothesize that the causative organism, Burkholderia pseudomallei, undergoes a process of adaptation involving altered expression of surface determinants which facilitates persistence in vivo and that this is reflected by changes in colony morphology. A colony morphotyping scheme and typing algorithm were developed using clinical B. pseudomallei isolates. Morphotypes were divided into seven types (denoted I to VII). Type I gave rise to other morphotypes (most commonly type II or III) by a process of switching in response to environmental stress, including starvation, iron limitation, and growth at 42°C. Switching was associated with complex shifts in phenotype, one of which (type I to type II) was associated with a marked increase in production of factors putatively associated with in vivo concealment. Isogenic types II and III, derived from type I, were examined using several experimental models. Switching between isogenic morphotypes occurred in a mouse model, where type II appeared to become adapted for persistence in a low-virulence state. Isogenic type II demonstrated a significant increase in intracellular replication fitness compared with parental type I after uptake by epithelial cells in vitro. Isogenic type III demonstrated a higher replication fitness following uptake by macrophages in vitro, which was associated with a switch to type II. Mixed B. pseudomallei morphologies were common in individual clinical specimens and were significantly more frequent in samples of blood, pus, and respiratory secretions than in urine and surface swabs. These findings have major implications for therapeutics and vaccine development.

Abstract 890: Feed-forward Signaling of TNF alpha and NFkappa B Produces Endothelial Dysfunction in Coronary Arterioles In Type Ii Diabetic Mice.

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Jiyeon Yang ◽  
Xiangbin Xu ◽  
Glen A Laine ◽  
Cuihua Zhang
Keyword(s):  
Oxidative Stress ◽  
Endothelial Dysfunction ◽  
Nuclear Factor Κb ◽  
Inhibitory Effect ◽  
Type Ii ◽  
Diabetic Mice ◽  
Necrosis Factor Alpha ◽  
Paramagnetic Resonance ◽  
Feed Forward ◽  
Coronary Arterioles

Nuclear factor-κB (NFκB) signaling reportedly increases tumor necrosis factor-alpha (TNF expression), and the oxidative stress induced by TNF may then lead to further increase NFκB expression, i.e., a feed-forward interaction. Accordingly, we hypothesized that this feed-forward interaction between TNF and NFκB may amplify one another toward the evolution of vascular disease in diabetes. To test this hypothesis, we assessed the role of NFκB in endothelial dysfunction in Lepr db mice by evaluation of endothelial function of isolated coronary resistance vessels of m Lepr db (heterozygote, normal) and Lepr db (homozygote, diabetic) mice. Coronary arterioles (40 –100 μm) were isolated and pressurized (60 cmH2O) without flow. Although dilation of vessels to the endothelium-independent vasodilator, sodium nitroprusside (SNP) was not different between Lepr db and m Lepr db mice (n = 6), dilation to the endothelium-dependent agonist, acetycholine (ACh) was reduced (n = 5, P < 0.05). Electron Paramagnetic Resonance (EPR) results show that superoxide production was reduced by NFκB antagonist (MG-132), or anti-TNF in Lepr db mice suggesting that NFκB and TNF were contributing to elevated oxidative stress. MG-132 (1 μM, n = 4) antagonized the inhibitory effect of Lepr db mice on ACh-induced dilation vs. Lepr db without treatment, but did not affect dilation in m Lepr db mice. To better understand the basis for enhanced contributions of TNF and NFκB in diabetes, we used Western analysis to assess expression of major proteins involved in TNF-mediated signaling. Previous studies have provided compelling evidence that IKK beta plays an essential role in NFκB activation in response to TNF, whereas IKK alpha appears to play a lesser role; therefore, we examined the expression levels of IKK alpha and IKK beta mRNA and protein in Lepr db null for TNF. The protein concentration and mRNA expression level of IKK alpha were increased in Lepr db mice null for TNF (db TNF- /db TNF- ) mice. One intriguing finding of this study is that the roles of IKK alpha and IKK beta appear reversed in the inflammatory response in diabetic Lepr db mice. Furthermore, our results indicate that NFκB and TNF signaling interact to amplify the oxidative stress and induce endothelial dysfunction in type II diabetes.

Dye coupling between rat striatal neurons recorded in vivo: compartmental organization and modulation by dopamine

1994 ◽  
Vol 71 (5) ◽  
pp. 1917-1934 ◽  
Author(s):  
S. P. Onn ◽  
A. A. Grace
Keyword(s):  
Intravenous Administration ◽  
D2 Receptor ◽  
Type I ◽  
Type Ii ◽  
Dye Coupling ◽  
Striatal Neurons ◽  
Receptor Stimulation ◽  
D2 Agonist ◽  
Response Profile

1. The presence of dye coupling between striatal neurons was investigated using in vivo intracellular recording and dye injection in adult rats. In 17% of the cases in which a single striatal neuron was injected with Lucifer yellow, more than one labeled neuron was recovered. In control rats, this dye coupling was observed only between single pairs of medium spiny neurons and only when the neuron injected exhibited the Type II response profile as defined by paired-pulse stimulation of corticostriatal afferents. 2. After intravenous administration of the D1/D2 agonist apomorphine at a behaviorally effective dose (i.e., 0.1–0.3 mg/kg), an increase in the incidence (from 17% to 82% of injected cells) and extent (from 2 cells to 3–7 cells labeled per injection) of dye coupling was observed. This effect was mediated by D2 receptor stimulation because administration of the D2 agonist quinpirole caused similar alterations in the incidence and extent of dye coupling (66% coupled). In contrast, administration of the D1 agonist SKF 38393 or the D1 antagonist SCH 23390 did not result in any significant alteration in dye coupling. 3. In control rats, the entire somatodendritic regions of dye-coupled neurons were found to be localized within single matrix compartments of the striatum. However, after intravenous administration of apomorphine or quinpirole, clusters of dye-coupled neurons were found to extend across the patch/matrix boundary. Moreover, dye coupling was observed after injecting cells exhibiting either the Type I or the Type II response profile. 4. In response to D2 receptor stimulation, both the extent and the pattern of coupling between striatal neurons is altered, resulting in direct coupling between neurons that are otherwise functionally and anatomically segregated in the control animal.

scholarly journals LeuRS can leucylate type I and type II tRNALeus in Streptomyces coelicolor

2019 ◽  
Vol 47 (12) ◽  
pp. 6369-6385
Author(s):  
Jia-Yi Fan ◽  
Qian Huang ◽  
Quan-Quan Ji ◽  
En-Duo Wang
Keyword(s):  
Tertiary Structure ◽  
Streptomyces Coelicolor ◽  
Catalytic Efficiency ◽  
Type I ◽  
Type Ii ◽  
Specific Domain ◽  
Recognition Mechanism ◽  
Variable Loop

Abstract Transfer RNAs (tRNAs) are divided into two types, type I with a short variable loop and type II with a long variable loop. Aminoacylation of type I or type II tRNALeu is catalyzed by their cognate leucyl-tRNA synthetases (LeuRSs). However, in Streptomyces coelicolor, there are two types of tRNALeu and only one LeuRS (ScoLeuRS). We found that the enzyme could leucylate both types of ScotRNALeu, and had a higher catalytic efficiency for type II ScotRNALeu(UAA) than for type I ScotRNALeu(CAA). The results from tRNA and enzyme mutagenesis showed that ScoLeuRS did not interact with the canonical discriminator A73. The number of nucleotides, rather than the type of base of the variable loop in the two types of ScotRNALeus, was determined as important for aminoacylation. In vitro and in vivo assays showed that the tertiary structure formed by the D-loop and TψC-loop is more important for ScotRNALeu(UAA). We showed that the leucine-specific domain (LSD) of ScoLeuRS could help LeuRS, which originally only leucylates type II tRNALeu, to aminoacylate type I ScotRNALeu(CAA) and identified the crucial amino acid residues at the C-terminus of the LSD to recognize type I ScotRNALeu(CAA). Overall, our findings identified a rare recognition mechanism of LeuRS to tRNALeu.

Loss of Gadd45a does not modify the pulmonary response to oxidative stress

2005 ◽  
Vol 288 (4) ◽  
pp. L663-L671 ◽  
Author(s):  
Jason M. Roper ◽  
Sean C. Gehen ◽  
Rhonda J. Staversky ◽  
M. Christine Hollander ◽  
Albert J. Fornace ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Epithelial Cells ◽  
Oxidative Dna Damage ◽  
Genotoxic Stress ◽  
Clara Cell ◽  
Heme Oxygenase 1 ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii

It is well established that exposure to high levels of oxygen (hyperoxia) injures and kills microvascular endothelial and alveolar type I epithelial cells. In contrast, significant death of airway and type II epithelial cells is not observed at mortality, suggesting that these cell types may express genes that protect against oxidative stress and damage. During a search for genes induced by hyperoxia, we previously reported that airway and alveolar type II epithelial cells uniquely express the growth arrest and DNA damage ( Gadd) 45a gene. Because Gadd45a has been implicated in protection against genotoxic stress, adult Gadd45a (+/+) and Gadd45a (−/−) mice were exposed to hyperoxia to investigate whether it protected epithelial cells against oxidative stress. During hyperoxia, Gadd45a deficiency did not affect loss of airway epithelial expression of Clara cell secretory protein or type II epithelial cell expression of pro-surfactant protein C. Likewise, Gadd45a deficiency did not alter recruitment of inflammatory cells, edema, or overall mortality. Consistent with Gadd45a not affecting the oxidative stress response, p21Cip1/WAF1 and heme oxygenase-1 were comparably induced in Gadd45a (+/+) and Gadd45a (−/−) mice. Additionally, Gadd45a deficiency did not affect oxidative DNA damage or apoptosis as assessed by oxidized guanine and terminal deoxyneucleotidyl transferase-mediated dUTP nick-end labeling staining. Overexpression of Gadd45a in human lung adenocarcinoma cells did not affect viability or survival during exposure, whereas it was protective against UV-radiation. We conclude that increased tolerance of airway and type II epithelial cells to hyperoxia is not attributed solely to expression of Gadd45a.

scholarly journals Fucoidan from Ascophyllum nodosum Suppresses Postprandial Hyperglycemia by Inhibiting Na+/Glucose Cotransporter 1 Activity

Marine Drugs ◽  
2020 ◽  
Vol 18 (9) ◽  
pp. 485
Author(s):  
Xindi Shan ◽  
Xueliang Wang ◽  
Hao Jiang ◽  
Chao Cai ◽  
Jiejie Hao ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Leptin Receptor ◽  
Specific Binding ◽  
Fasting Blood Glucose ◽  
Postprandial Hyperglycemia ◽  
Oral Glucose ◽  
Type I ◽  
Type Ii ◽  
Everted Gut Sac

We previously demonstrated that fucoidan with a type II structure inhibited postprandial hyperglycemia by suppressing glucose uptake, but the mechanism remains elusive. Here, we aimed to assess whether the effect of glucose absorption inhibition was related to the basic structure of fucoidans and preliminarily clarified the underlying mechanism. Fucoidans with type II structure and type I structure were prepared from Ascophyllumnodosum (AnF) or Laminariajaponica (LjF) and Kjellmaniellacrassifolia (KcF), respectively. The effects of various fucoidans on suppressing postprandial hyperglycemia were investigated using in vitro (Caco-2 monolayer model), semi-in vivo (everted gut sac model), and in vivo (oral glucose tolerance test, OGTT) assays. The results showed that only AnF with a type II structure, but not LjF or KcF with type I structure, could inhibit the glucose transport in the Caco-2 monolayer and everted gut sac models. A similar result was seen in the OGTT of Kunming mice and leptin receptor-deficient (db/db) mice, where only AnF could effectively inhibit glucose transport into the bloodstream. Furthermore, AnF (400 mg/kg/d) treatment decreased the fasting blood glucose, HbA1c, and fasting insulin levels, while increasing the serum glucagon-like peptide-1 (GLP-1) level in obese leptin receptor-deficient (db/db) mice. Furthermore, surface plasmon resonance (SPR) analysis revealed the specific binding of AnF to Na+/glucose cotransporter 1 (SGLT1), which indicated the effect of AnF on postprandial hyperglycemia could be due to its suppression on SGLT1 activity. Taken together, this study suggests that AnF with a type II structure can be a promising candidate for hyperglycemia treatment.

Sign in / Sign up

Export Citation Format

Share Document