A Transient Heating Technique for the Measurement of Thermal Properties of Perfused Biological Tissue

1985 ◽  
Vol 107 (3) ◽  
pp. 219-227 ◽  
Author(s):  
W. H. Newman ◽  
P. P. Lele
Keyword(s):  
Steady State ◽  
Thermal Diffusivity ◽  
Biological Tissue ◽  
Kidney Tissue ◽  
Transfer Model ◽  
Transient Heating ◽  
Pulse Technique ◽  
Local Tissue

Knowledge of tissue thermal transport properties is imperative for any therapeutic medical tool which employs the localized application of heat to perfused biological tissue. In this study, several techniques are proposed to measure local tissue thermal diffusion by heating with a focused ultrasound field. Transient as well as near steady-state heat inputs are discussed and examined for their suitability as a measurement technique for either tissue thermal diffusivity or perfusion rate. It is shown that steady-state methods are better suited for the measurement of perfusion; however the uncertainty in the perfusion measurement is directly related to knowledge of the tissue’s intrinsic thermal diffusivity. Results are presented for a transient thermal pulse technique for the measurement of the thermal diffusivity of perfused and nonperfused tissues, in vitro and in vivo. Measurements conducted in plexiglas, animal muscle, kidney and brain concur with tabulated values and show a scatter from 5–15 percent from the mean; measurements made in perfused muscle and brain compare well with the nonperfused values. An estimate of the error introduced by the effect of perfusion shows that except for highly perfused kidney tissue the effect of perfusion is less than the experimental scatter. This validation of the tissue heat transfer model will allow its eventual extension to the simultaneous measurement of local tissue thermal diffusivity and perfusion.

scholarly journals Activating Signal Cointegrator 2 Belongs to a Novel Steady-State Complex That Contains a Subset of Trithorax Group Proteins

2003 ◽  
Vol 23 (1) ◽  
pp. 140-149 ◽  
Author(s):  
Young-Hwa Goo ◽  
Young Chang Sohn ◽  
Dae-Hwan Kim ◽  
Seung-Whan Kim ◽  
Min-Jung Kang ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Steady State ◽  
Nuclear Receptors ◽  
Transcriptional Activation ◽  
Retinoic Acid Receptor ◽  
Dependent Manner ◽  
Trithorax Group ◽  
Trithorax Group Proteins

ABSTRACT Many transcription coactivators interact with nuclear receptors in a ligand- and C-terminal transactivation function (AF2)-dependent manner. These include activating signal cointegrator 2 (ASC-2), a recently isolated transcriptional coactivator molecule, which is amplified in human cancers and stimulates transactivation by nuclear receptors and numerous other transcription factors. In this report, we show that ASC-2 belongs to a steady-state complex of approximately 2 MDa (ASC-2 complex [ASCOM]) in HeLa nuclei. ASCOM contains retinoblastoma-binding protein RBQ-3, α/β-tubulins, and trithorax group proteins ALR-1, ALR-2, HALR, and ASH2. In particular, ALR-1/2 and HALR contain a highly conserved 130- to 140-amino-acid motif termed the SET domain, which was recently implicated in histone H3 lysine-specific methylation activities. Indeed, recombinant ALR-1, HALR, and immunopurified ASCOM exhibit very weak but specific H3-lysine 4 methylation activities in vitro, and transactivation by retinoic acid receptor appears to involve ligand-dependent recruitment of ASCOM and subsequent transient H3-lysine 4 methylation of the promoter region in vivo. Thus, ASCOM may represent a distinct coactivator complex of nuclear receptors. Further characterization of ASCOM will lead to a better understanding of how nuclear receptors and other transcription factors mediate transcriptional activation.

The anterior and posterior ‘stomach’ regions of larval Aedes aegypti midgut: regional specialization of ion transport and stimulation by 5-hydroxytryptamine

1999 ◽  
Vol 202 (3) ◽  
pp. 247-252 ◽  
Author(s):  
T.M. Clark ◽  
A. Koch ◽  
D.F. Moffett
Keyword(s):  
Steady State ◽  
Aedes Aegypti ◽  
Ion Transport ◽  
Malpighian Tubules ◽  
Transport Mechanisms ◽  
Regional Specialization ◽  
Negative Deflection ◽  
Electrical Polarity

The ‘stomach’ region of the larval mosquito midgut is divided into histologically distinct anterior and posterior regions. Anterior stomach perfused symmetrically with saline in vitro had an initial transepithelial potential (TEP) of −66 mV (lumen negative) that decayed within 10–15 min to a steady-state TEP near −10 mV that was maintained for at least 1 h. Lumen-positive TEPs were never observed in the anterior stomach. The initial TEP of the perfused posterior stomach was opposite in polarity, but similar in magnitude, to that of the anterior stomach, measuring +75 mV (lumen positive). This initial TEP of the posterior stomach decayed rapidly at first, then more slowly, eventually reversing the electrical polarity of the epithelium as lumen-negative TEPs were recorded in all preparations within 70 min. Nanomolar concentrations of the biogenic amine 5-hydroxytryptamine (5-HT, serotonin) stimulated both regions, causing a negative deflection of the TEP of the anterior stomach and a positive deflection of the TEP of the posterior stomach. Phorbol 12,13-diacetate also caused a negative deflection of the TEP of the anterior stomach, but had no effect on the TEP of the posterior stomach. These data demonstrate that 5-HT stimulates region-specific ion-transport mechanisms in the stomach of Aedes aegypti and suggest that 5-HT coordinates the actions of the Malpighian tubules and midgut in the maintenance of an appropriate hemolymph composition in vivo.

Evaluation of vecabrutinib as a model for non-covalent BTK/ITK inhibition for treatment of chronic lymphocytic leukemia

Blood ◽  
2021 ◽  
Author(s):  
Billy Michael Chelliah Jebaraj ◽  
Annika Müller ◽  
Rashmi Priyadharshini Dheenadayalan ◽  
Sascha Endres ◽  
Philipp M. Roessner ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Chronic Lymphocytic Leukemia ◽  
Inhibitory Effect ◽  
Lymphocytic Leukemia ◽  
Transfer Model ◽  
Treatment Benefit ◽  
Btk Inhibitors

Covalent Bruton tyrosine kinase (BTK) inhibitors such as ibrutinib have proven to be highly beneficial in the treatment of chronic lymphocytic leukemia (CLL). Interestingly, the off-target inhibition of IL-2-inducible T-cell kinase (ITK) by ibrutinib may also play a role in modulating the tumor microenvironment, potentially enhancing the treatment benefit. However, resistance to covalently binding BTK inhibitors can develop by a mutation in cysteine 481 of BTK (C481S), which prevents the irreversible binding of the drugs. In the present study we performed pre-clinical characterization of vecabrutinib, a next generation non-covalent BTK inhibitor, with ITK inhibitory properties similar to those of ibrutinib. Unlike ibrutinib and other covalent BTK inhibitors, vecabrutinib showed retention of the inhibitory effect on C481S BTK mutants in vitro, similar to that of wildtype BTK. In the murine Eµ-TCL1 adoptive transfer model, vecabrutinib reduced tumor burden and significantly improved survival. Vecabrutinib treatment led to a decrease in CD8+ effector and memory T-cell populations, while the naïve populations were increased. Of importance, vecabrutinib treatment significantly reduced frequency of regulatory CD4+ T-cells (Tregs) in vivo. Unlike ibrutinib, vecabrutinib treatment showed minimal adverse impact on activation and proliferation of isolated T-cells. Lastly, combination treatment of vecabrutinib with venetoclax was found to augment treatment efficacy, significantly improve survival and lead to favourable reprogramming of the microenvironment in the murine Eµ-TCL1 model. Thus, non-covalent BTK/ITK inhibitors such as vecabrutinib may be efficacious in C481S BTK mutant CLL, while preserving the T-cell immunomodulatory function of ibrutinib.

GABA receptors precede glutamate receptors in hypothalamic development; differential regulation by astrocytes

1995 ◽  
Vol 74 (4) ◽  
pp. 1473-1484 ◽  
Author(s):  
G. Chen ◽  
P. Q. Trombley ◽  
A. N. van den Pol
Keyword(s):  
Steady State ◽  
Amino Acid ◽  
Glutamate Receptors ◽  
Gaba Receptors ◽  
Receptor Expression ◽  
Glycine Receptors ◽  
Hypothalamic Neurons ◽  
Amino Acid Receptors

1. The developmental changes in gamma-aminobutyrate (GABA)-, glutamate-, and glycine-mediated currents in cultured embryonic neurons (n = 134) from rat hypothalamus were studied with the use of whole cell voltage-clamp recording. 2. GABA-evoked currents were detected in neurons cultured from 15-day embryos (E15) a few hours after plating. Every neuron studied from the time of plating at E15 to 2 wk later responded to GABA (30 microM). The peak and steady-state currents evoked by GABA increased by four- to fivefold within 2 wk in culture. The time constants of the desensitization of GABA currents did not change during this period. The properties of the responses to GABA were not altered by different culture densities or substrates. 3. Glycine activated receptors that were pharmacologically distinct from GABA receptors on hypothalamic neurons. The glycine responses increased by > 50-fold within 2 wk in culture. The percentage of cells responding to glycine (500 microM) was 20% at 0 days in vitro (DIV), and increased to 100% at 6 DIV. Astrocytes increased both the amplitude of glycine-mediated currents and the percentage of cells responding to glycine. 4. Glutamate-mediated currents developed later than GABA-mediated currents. The percentage of cells responding to glutamate (500 microM) increased within the 1st wk, from 20% on the day of plating to 100% after 6 DIV. Both the peak currents and the steady-state currents mediated by glutamate increased by 20-fold during the 2 wk in culture. Both the amplitude of the responses to glutamate and the percentage of cells responding to glutamate were increased by growing neurons either on an astrocyte substrate or in high-density cultures. 5. The currents and conductance changes elicited by GABA were greater than those generated by glutamate or glycine throughout the period examined. This difference was particularly evident in younger cells. After 3 days in vitro, GABA (30 microM) elicited a mean current of 1,648 pA, whereas glutamate (500 microM) only elicited a 266-pA current, and glycine (500 microM) elicited a 278-pA current from neurons growing on an astrocyte layer. 6. The expression of amino acid receptors was heterogeneous among hypothalamic neurons in younger cultures. Whereas all neurons expressed GABA receptors, some developing neurons did not express detectable glutamate receptors or glycine receptors. 7. Each of the three amino acid-evoked currents increased from E15 (1 DIV) to E20 (1 DIV), indicating an intrinsic development in the expression of the amino acid receptors in vivo. The GABA, glutamate, and glycine currents at E15, 10 DIV were similar to the currents at E20, 5 DIV (both 25 days after conception), suggesting parallel developmental patterns for amino acid receptor expression in vitro and in vivo. 8. Together, these data suggest that GABA may play a major role in early development because hypothalamic neurons are more sensitive to GABA than to either glutamate or glycine. However, glutamate and glycine receptors appear more sensitive to regulation by the local environment than GABA receptors because culture density and the astrocyte substrate have greater inductive effects on glutamate and glycine receptors than on GABA receptors.

scholarly journals In Vitro and In Vivo Antifungal Activity of AmBisome Compared to Conventional Amphotericin B and Fluconazole against Candida auris

2021 ◽  
Author(s):  
Janet Herrada ◽  
Ahmed Gamal ◽  
Lisa Long ◽  
Sonia P. Sanchez ◽  
Thomas S. McCormick ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Amphotericin B ◽  
Kidney Tissue ◽  
Treated Group ◽  
Untreated Group ◽  
Candida Auris ◽  
Fungal Burden ◽  
In Vivo Antifungal Activity

Antifungal activity of AmBisome against Candida auris was determined in vitro and in vivo. AmBisome showed MIC50 and MIC90 values of 1 and 2 μg/mL, respectively. Unlike conventional amphotericin B, significant in vivo efficacy was observed in the AmBisome 7.5 mg/kg -treated group in survival and reduction of kidney tissue fungal burden compared to the untreated group. Our data shows that AmBisome shows significant antifungal activity against C. auris in vitro as well as in vivo.

scholarly journals Improving the Antitumor Activity and Bioavailability of Sonidegib for the Treatment of Skin Cancer

Pharmaceutics ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1560
Author(s):  
Amr Gamal ◽  
Haitham Saeed ◽  
Fatma I. Abo El-Ela ◽  
Heba F. Salem
Keyword(s):  
Steady State ◽  
Skin Cancer ◽  
Entrapment Efficiency ◽  
The United States ◽  
Relative Bioavailability ◽  
Passive Targeting ◽  
Therapeutic Benefits ◽  
Steady State Flux

Throughout the United States and the world, skin cancer is the most frequent form of cancer. Sonidegib (SNG) is a hedgehog inhibitor that has been used for skin cancer treatment. However, SNG has low bioavailability and is associated with resistance. The focus of this work is to enhance bioavailability, anti-tumor efficacy and targeting of SNG via developing ethosome gel as a potential treatment for skin cancer. SNG-loaded ethosomes formulation was prepared and characterized in vitro by %entrapment efficiency (%EE), vesicle size, morphology, %release and steady-state flux. The results showed that the prepared formulation was spherical nanovesicles with a %EE of 85.4 ± 0.57%, a particle size of 199.53 ± 4.51 nm and a steady-state flux of 5.58 ± 0.08 µg/cm2/h. In addition, SNG-loaded ethosomes formulation was incorporated into carbopol gel to study the anti-tumor efficacy, localization and bioavailability in vivo. Compared with oral SNG, the formulation showed 3.18 times higher relative bioavailability and consequently significant anti-tumor activity. In addition, this formulation showed a higher rate of SNG penetration in the skin’s deep layers and passive targeting in tumor cells. Briefly, SNG-loaded ethosome gel can produce desirable therapeutic benefits for treatment of skin cancer.

scholarly journals CD47 prevents the elimination of diseased fibroblasts in scleroderma

2020 ◽  
Author(s):  
Tristan Lerbs ◽  
Lu Cui ◽  
Megan E. King ◽  
Tim Chai ◽  
Claire Muscat ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Immune System ◽  
Autoimmune Disease ◽  
Skin Fibrosis ◽  
Transfer Model ◽  
Self Renewal ◽  
Syngeneic Mouse ◽  
Fibrotic Tissue

AbstractScleroderma is a devastating fibrotic autoimmune disease. Current treatments are partly effective in preventing disease progression, but do not remove fibrotic tissue. Here, we evaluated whether scleroderma fibroblasts take advantage of the “don’t-eat-me-signal” CD47 and whether blocking CD47 enables the body’s immune system to get rid of diseased fibroblasts. To test this approach, we used a Jun-inducible scleroderma model. We first demonstrated in patient samples that scleroderma upregulated JUN and increased promotor accessibilities of both JUN and the CD47. Next, we established our scleroderma model demonstrating that Jun mediated skin fibrosis through the hedgehog-dependent expansion of CD26+Sca1-fibroblasts in mice. In a niche-independent adaptive transfer model, JUN steered graft survival and conferred increased self-renewal to fibroblasts. In vivo, JUN enhanced the expression of CD47, and inhibiting CD47 eliminated an ectopic fibroblast graft and increased in vitro phagocytosis. In the syngeneic mouse, depleting macrophages ameliorated skin fibrosis. Therapeutically, combined CD47 and IL6 blockade reversed skin fibrosis in mice and led to the rapid elimination of ectopically transplanted scleroderma cells. Altogether, our study is the first to demonstrate the efficiency of combining different immunotherapies in treating scleroderma and provide a rationale for combining CD47 and IL6 inhibition in clinical trials.

RAP1 is required for BAS1/BAS2- and GCN4-dependent transcription of the yeast HIS4 gene

1991 ◽  
Vol 11 (7) ◽  
pp. 3642-3651 ◽  
Author(s):  
C Devlin ◽  
K Tice-Baldwin ◽  
D Shore ◽  
K T Arndt
Keyword(s):  
Steady State ◽  
Binding Site ◽  
Binding Sites ◽  
Binding Activity ◽  
Micrococcal Nuclease ◽  
Mrna Levels ◽  
High Affinity ◽  
Steady State Levels

The major in vitro binding activity to the Saccharomyces cerevisiae HIS4 promoter is due to the RAP1 protein. In the absence of GCN4, BAS1, and BAS2, the RAP1 protein binds to the HIS4 promoter in vivo but cannot efficiently stimulate HIS4 transcription. RAP1, which binds adjacently to BAS2 on the HIS4 promoter, is required for BAS1/BAS2-dependent activation of HIS4 basal-level transcription. In addition, the RAP1-binding site overlaps with the single high-affinity HIS4 GCN4-binding site. Even though RAP1 and GCN4 bind competitively in vitro, RAP1 is required in vivo for (i) the normal steady-state levels of GCN4-dependent HIS4 transcription under nonstarvation conditions and (ii) the rapid increase in GCN4-dependent steady-state HIS4 mRNA levels following amino acid starvation. The presence of the RAP1-binding site in the HIS4 promoter causes a dramatic increase in the micrococcal nuclease sensitivity of two adjacent regions within HIS4 chromatin: one region contains the high-affinity GCN4-binding site, and the other region contains the BAS1- and BAS2-binding sites. These results suggest that RAP1 functions at HIS4 by increasing the accessibility of GCN4, BAS1, and BAS2 to their respective binding sites when these sites are present within chromatin.

Application of an automated small-scale in vitro transfer model to predict in vivo precipitation inhibition

2019 ◽  
Vol 565 ◽  
pp. 458-471 ◽  
Author(s):  
Christian Jede ◽  
Christian Wagner ◽  
Holger Kubas ◽  
Christian Weber ◽  
Markus Weigandt ◽  
...  
Keyword(s):  
Small Scale ◽  
Transfer Model ◽  
Precipitation Inhibition
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