Investigation of the effect of verapamil on the regional absorption of sofosbuvir from rabbit intestine in situ

2022 ◽  
Author(s):  
Nada M. Mohsen ◽  
Esmat E. Zein El-Din ◽  
Mohamed A. Osman ◽  
Shimaa M. Ashmawy
Keyword(s):  
Rabbit Intestine

Cellular and regional expression of transcripts of the plasma membrane calcium pump PMCA1 in rabbit intestine

1995 ◽  
Vol 269 (1) ◽  
pp. G126-G131 ◽  
Author(s):  
T. C. Freeman ◽  
A. Howard ◽  
B. S. Bentsen ◽  
S. Legon ◽  
J. R. Walters
Keyword(s):  
Plasma Membrane ◽  
In Situ Hybridization ◽  
Splicing Variants ◽  
Intestinal Segments ◽  
Rabbit Intestine ◽  
Dependent Absorption ◽  
Small Intestinal ◽  
Energy Dependent ◽  
Rna Blots

The plasma membrane Ca(2+)-pumping adenosinetriphosphatase (PMCA) is the energy-dependent step in the active vitamin D-dependent absorption of dietary Ca2+ by the enterocyte. Studies of the various PMCA genes and splicing variants in humans and rats have indicated that the isoform known as PMCA1b is the predominant form expressed in small intestine. Using an oligonucleotide probe, we have studied the regional and cellular distribution of PMCA1 transcripts in rabbit intestinal tissues by in situ hybridization. On small intestinal RNA blots, this hybridized to species similar in size to those detected by PMCA1-specific cDNA probes; an additional larger transcript was present in rabbit than in rat or human. In situ hybridization signals were principally in the enterocyte population of the mucosa and were maximal in differentiating enterocytes on the lower part of the villus, a pattern similar to that previously demonstrated for other nutrient transporters. Reflecting the capacity of the different small intestinal segments to transport Ca2+, much higher levels of transcript were detected by both methods proximally (in duodenum) than distally (in jejunum and ileum) and were also higher in cecum and ascending colon mucosa than in descending colon. We conclude that as enterocytes differentiate in regions that absorb Ca2+, they express high levels of mRNA for PMCA1. These results confirm the importance of transcriptional regulation of this gene for active Ca2+ absorption.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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