Glucose absorption by in vitro perfused ileum of the fetal rat

1982 ◽  
Vol 242 (6) ◽  
pp. G642-G649
Author(s):  
G. D. Potter ◽  
K. L. Schmidt ◽  
R. Lester ◽  
S. G. Schultz
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Average Molecular Weight ◽  
Glucose Absorption ◽  
Rat Ileum ◽  
Fetal Rat ◽  
Before And After ◽  
Luminal Perfusion ◽  
Unidirectional Fluxes

In vitro intraluminal perfusion of the fetal rat ileum at 19 and 20 days of gestation was employed to measure the rate of glucose absorption and the unidirectional fluxes of 3-O-methylglucose (3-O-MG). Fetal ileum was mounted on pipettes within an oxygenated bath and perfused with a solution containing glucose or 3-O-MG and polyethylene glycol with average molecular weight of 4,000 (PEG) as a marker substance. We verified that the PEG was not transported and did not diffuse across the fetal ileum. Scanning and electron microscopy before and after perfusion demonstrated preservation of mucosal anatomy. The rate of glucose absorption was 200 +/- 17 mumol.h-1.g-1 at 19 days and increased significantly to 378 +/- 12 mumol.h-1.g-1 at 20 days. The absence of sodium abolished this process. The flux of 3-O-MG from lumen to bath was 88 +/- 10 mumol.h-1.g-1 at 19 days and 160 +/- 16 mumol.h-1.g-1 at 20 days. Bath-to-lumen flux was -17 +/- 2 mumol.h-1.g-1 and did not vary with age. Active, rapidly developing transport of glucose and 3-O-MG is demonstrated by in vitro luminal perfusion of the fetal rat ileum at 19 days.

Glucose absorption by in vitro perfused colon of the fetal rat

1983 ◽  
Vol 245 (3) ◽  
pp. G424-G430 ◽  
Author(s):  
G. D. Potter ◽  
K. L. Schmidt ◽  
R. Lester
Keyword(s):  
Small Bowel ◽  
Average Molecular Weight ◽  
Glucose Absorption ◽  
Physiological Solution ◽  
Rat Colon ◽  
Transmission Electron ◽  
Fetal Rat ◽  
Luminal Perfusion ◽  
And Control

The anatomic configuration of fetal rat colon resembles that of the small bowel. Accordingly, glucose and amino acid absorption were measured in order to see whether the fetal rat colon resembled the small bowel functionally. In vitro luminal perfusion of the fetal rat colon at 20 days of gestation was employed to measure the rate of glucose and L-alanine absorption and the unidirectional flux rates of 3-O-methylglucose (3-O-MG). The colon was mounted between pipettes in a heated oxygenated bath and perfused with the solute to be studied dissolved in buffered physiological solution and polyethylene glycol with average molecular weight of 4,000 (PEG) as a nonabsorbable marker substance. The PEG was not transported and did not diffuse across fetal colon. Scanning and transmission electron microscopy of perfused and control colon showed the presence of villi and the preservation of mucosal anatomy during perfusion. Glucose was absorbed at 173 +/- 16 mumol . h-1 . g-1 (8) and absorption was abolished in Na-free solution. 3-O-MG flux was 40 +/- 7 mumol . h-1 . g-1 (8) from lumen to bath and 7 +/- 1 mumol . h-1 . g-1 (8) from bath to lumen. L-Alanine flux was 130 +/- 15 mumol . h-1 . g-1 (8) from lumen to bath and 18 +/- 4 mumol . h-1 . g-1 (5) from bath to lumen, and the lumen-to-bath flux was only partially abolished by Na-free solutions.

Temporal changes in glucose and carbohydrate metabolism in the oncospheres of the cyclophyllidean tapeworm, Hymenolepis diminuta

Parasitology ◽  
1993 ◽  
Vol 106 (3) ◽  
pp. 317-325 ◽  
Author(s):  
P. W. Pappas ◽  
G. M. Durka
Keyword(s):  
Molecular Weight ◽  
Glucose Metabolism ◽  
Carbohydrate Metabolism ◽  
Glucose Absorption ◽  
Temporal Changes ◽  
Hymenolepis Diminuta ◽  
Temporal Shift ◽  
Carbohydrate Fraction ◽  
Ethanol Extracts

SUMMARYWhen incubated in vitro for 24 h, oncospheres of Hymenolepis diminuta absorb and metabolize radioactive glucose. Between 0 and 12 h post-activation, oncospheres absorb glucose, but glucose is neither metabolized into other carbohydrates nor incorporated into the ethanol-precipitable fraction (which would contain glycogen). Between 12 and 24 h post-activation glucose is incorporated into a number of higher molecular weight carbohydrates that are demonstrable in ethanol extracts of the larvae, as well as the incubation media. Furthermore, measurable amounts of radioactivity are incorporated into the ethanol-precipitable carbohydrate fraction of oncospheres. To determine if these temporal changes in carbohydrate metabolism occurred spontaneously following activation, oncospheres were pre-incubated for 12 h (0–12 h post-activation) in the absence or presence of glucose, and then transferred to media containing radioactive glucose for an additional 12 h (12–24 h post-activation). In these latter experiments, glucose absorption and metabolism between 12 and 24 h post-activation were virtually identical to glucose metabolism in oncospheres that were incubated in radioactive glucose for 0–12 h immediately following activation. Thus, these data do not support the hypothesis that the temporal shift in carbohydrate metabolism occurs spontaneously.

scholarly journals Average molecular weight of surfactants in aerosols

2007 ◽  
Vol 7 (5) ◽  
pp. 13805-13838 ◽  
Author(s):  
M. T. Latif ◽  
P. Brimblecombe
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Atmospheric Aerosols ◽  
Average Molecular Weight ◽  
Molecular Size ◽  
Weight Fraction ◽  
Ozone Exposure ◽  
Before And After ◽  
Fine Mode ◽  
Active Substances

Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can be correlated with surface tension as determined by pendant drop analysis. The effect of surface tension was more clearly indicated in fine mode aerosol extracts. The concentration of MBAS and EVAS was determined before and after ultrafiltration analysis using AMICON centrifuge tubes that define a 5000 Da (5 K Da) nominal molecular weight fraction. Overall, MBAS and to a greater extent EVAS predominates in fraction with molecular weight below 5 K Da. In case of aerosols collected in Malaysia the higher molecular fractions tended to be a more predominant. The MBAS and EVAS are correlated with yellow to brown colours in aerosol extracts. Further experiments showed possible sources of surfactants (e.g. petrol soot, diesel soot) in atmospheric aerosols to yield material having molecular size below 5 K Da except for humic acid. The concentration of surfactants from these sources increased after ozone exposure and for humic acids it also general included smaller molecular weight surfactants.

scholarly journals Fighting SARS-CoV-2 with green seaweed Ulva sp. extract: extraction protocol predetermines crude ulvan extract anti-SARS-CoV-2 inhibition properties in in vitro Vero-E6 cells assay

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12398
Author(s):  
Shai Shefer ◽  
Arthur Robin ◽  
Alexander Chemodanov ◽  
Mario Lebendiker ◽  
Robert Bostwick ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chemical Composition ◽  
Antiviral Activity ◽  
Cytopathic Effect ◽  
Average Molecular Weight ◽  
Ammonium Oxalate ◽  
Extraction Protocol ◽  
Reduction Assay ◽  
Green Seaweed

Due to the global COVID-19 pandemic, there is a need to screen for novel compounds with antiviral activity against SARS-COV-2. Here we compared chemical composition and the in vitro anti- SARS-COV-2 activity of two different Ulva sp. crude ulvan extracts: one obtained by an HCl-based and another one by ammonium oxalate-based (AOx) extraction protocols. The composition of the crude extracts was analyzed and their antiviral activity was assessed in a cytopathic effect reduction assay using Vero E6 cells. We show that the extraction protocols have a significant impact on the chemical composition, anti- SARS-COV-2 activity, and cytotoxicity of these ulvan extracts. The ulvan extract based on the AOx protocol had a higher average molecular weight, higher charge, and 11.3-fold higher antiviral activity than HCl-based extract. Our results strongly suggest that further bioassay-guided investigation into bioactivity of compounds found in Ulva sp. ulvan extracts could lead to the discovery of novel anti-SARS-CoV-2 antivirals.

scholarly journals Effect of Natural Fermentation of Sorghum on Resistant Starch Molecular Structure and Fermentation Property

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
YunFei Ge ◽  
WeiHao Wang ◽  
Meng Shen ◽  
ZiYue Kang ◽  
Juan Wang ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Butyric Acid ◽  
Resistant Starch ◽  
Short Chain ◽  
In Vitro Fermentation ◽  
Percentage Content ◽  
Research Results ◽  
Before And After

Relevant research results have suggested that fermentation can increase the content of sorghum amylose chains and their retrogradation value. Therefore, this study explored the effect of fermentation pretreatment on the yield, digestibility, molecular structure, and in vitro fermentation property of sorghum-resistant starch by conducting fermentation pretreatment of sorghum and extracting the resistant starch from fermented sorghum with pressure-heat compound enzyme method. The results were as follows. After fermentation pretreatment, the yield of sorghum-resistant starch increased, the digestibility of sorghum-resistant starch reduced, the laminated structure size on the surface of the particles became more uniform, and the stacking mode became more neat and denser. The sorghum-resistant starch prepared before and after fermentation did not produce new chemical groups, and its functional group peak remained unchanged. After fermentation, the weight-average molecular weight of sorghum-resistant starch was elevated, and the percentage content of high- and low-molecular substances increased and decreased, respectively, compared with that of the unfermented sorghum-resistant starch. The percentage content of short-chain branches in the branched chain increased, whereas that of the long-chain branches decreased; the crystallinity of sorghum-resistant starch after fermentation decreased, and the intensity of X-diffraction peak changed slightly before and after fermentation. According to the results of the in vitro fermentation experiments, the fermentation broth of sorghum-resistant starch had the highest content of butyric acid and short-chain fatty acid. Research results reveal that, after fermentation pretreatment, sorghum-resistant starch presented increased yield, more complex molecular structure, heavier molecular weight and more uniform surface morphology, more efficient butyric acid generation, and greater fermentation rate than unfermented sorghum-resistant starch.

Electron microscopy of a dna helix destabilizing protein crystal (gp32*i)

1978 ◽  
Vol 36 (2) ◽  
pp. 178-179 ◽  
Author(s):  
Wah Chiu ◽  
Junko Hosoda
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Dna Replication ◽  
Bacteriophage T4 ◽  
Polystyrene Latex ◽  
Protein Crystal ◽  
Low Salt ◽  
Leading Strand ◽  
Gene 32

Gp 32 is a protein coded by gene 32 in bacteriophage T4. It is essential for DNA replication, recombination and repair. Gp32*I with molecular weight of 27,000 was obtained by proteolytic removal of 8000-dalton peptide from COOH-terminal of gp32 (Hosoda et al. to be published). It is a stronger helix destabilizer than gp32, and has been found to be able to replace gp32 in constructing an in vitro DNA replication apparatus, which is active in the leading strand synthesis.Thin gp32*I crystal was formed under a low salt condition in the absence of glycerol. Figure 1 shows a typical image of the crystal embedded in 1% glucose taken at low magnification. The optical diffractogram in the insert confirms the crystallinity, though no visible feature is seen in the micrograph due to the low magnification power. By using the tungsten shadowing technique, the thickness of the crystal was measured, along with polystyrene latex spheres as a standard, to be between 85 to 400 Å.

In vitro synthesis of glycogen: the structure, properties, and physiological function of enzymatically-synthesized glycogen

Biologia ◽  
2011 ◽  
Vol 66 (3) ◽  
Author(s):  
Hideki Kajiura ◽  
Hiroki Takata ◽  
Tsunehisa Akiyama ◽  
Ryo Kakutani ◽  
Takashi Furuyashiki ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Large Scale ◽  
Glycogen Synthesis ◽  
Average Molecular Weight ◽  
Spherical Particles ◽  
Average Chain Length ◽  
Scale Production ◽  
In Vitro Synthesis

AbstractThis review describes a new enzymatic method for in vitro glycogen synthesis and its structure and properties. In this method, short-chain amylose is used as the substrate for branching enzymes (BE, EC 2.4.1.18). Although a kidney bean BE and Bacillus cereus BE could not synthesize high-molecular weight glucan, BEs from 6 other bacterial sources produced enzymatically synthesized glycogen (ESG). The BE from Aquifex aeolicus was the most suitable for the production of glycogen with a weight-average molecular weight (M w) of 3,000–30,000 k. The molecular weight of the ESG is controllable by changing the concentration of the substrate amylose. Furthermore, the addition of amylomaltase (AM, EC 2.4.1.25) significantly enhanced the efficiency of this process, and the yield of ESG reached approximately 65%. Typical preparations of ESG obtained by this method were subjected to structural analyses. The average chain length, interior chain length, and exterior chain length of the ESGs were 8.2–11.6, 2.0–3.3, and 4.2–7.6, respectively. Transmission electron microscopy and intrinsic viscosity measurement showed that the ESG molecules formed spherical particles. Unlike starch, the ESGs were barely degraded by pullulanase. Solutions of ESG were opalescent (milky-white and slightly bluish), and gave a reddishbrown color on the addition of iodine. These analyses revealed that ESG shares similar molecular shapes and solution properties with natural-source glycogen. Moreover, ESG had macrophage-stimulating activity and its activity depends on the molecular weight of ESG. We successfully achieved large scale production of ESG. ESG could lead to new industrial applications, such as in the food, chemical, and pharmaceutical fields.

scholarly journals Selection of Water-Soluble Chitosan by Microwave-Assisted Degradation and pH-Controlled Precipitation

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1274 ◽  
Author(s):  
Céline M. A. Journot ◽  
Laura Nicolle ◽  
Yann Lavanchy ◽  
Sandrine Gerber-Lemaire
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Aqueous Media ◽  
Phase Changes ◽  
Water Soluble ◽  
In Vivo Evaluation ◽  
Microwave Assisted ◽  
Selection Of

In the field of gene therapy, chitosan (CS) gained interest for its promise as a non-viral DNA vector. However, commercial sources of CS lack precise characterization and do not generally reach sufficient solubility in aqueous media for in vitro and in vivo evaluation. As low molecular weight CS showed improved solubility, we investigated the process of CS depolymerization by acidic hydrolysis, using either long time heating at 80 °C or short time microwave-enhanced heating. The resulting depolymerized chitosan (dCS) were analyzed by gel permeation chromatography (GPC) and 1H nuclear magnetic resonance (NMR) to determine their average molecular weight (Mn, Mp and Mw), polydispersity index (PD) and degree of deacetylation (DD). We emphasized the production of water-soluble CS (solubility > 5 mg/mL), obtained in reproducible yield and characteristics, and suitable for downstream functionalization. Optimal microwave-assisted conditions provided dCS with a molecular weight (MW) = 12.6 ± 0.6 kDa, PD = 1.41 ± 0.05 and DD = 85%. While almost never discussed in the literature, we observed the partial post-production aggregation of dCS when exposed to phase changes (from liquid to solid). Repeated cycles of freezing/thawing allowed the selection of dCS fractions which were exempt of crystalline particles formation upon solubilization from frozen samples.

scholarly journals The cercarial glycocalyx of Schistosoma mansoni.

1985 ◽  
Vol 100 (5) ◽  
pp. 1423-1434 ◽  
Author(s):  
J C Samuelson ◽  
J P Caulfield
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Schistosoma Mansoni ◽  
High Molecular Weight ◽  
Membrane Surface ◽  
Periodate Oxidation ◽  
Apparent Molecular Weight ◽  
Ruthenium Red ◽  
Unit Membrane

Cercariae, the freshwater stage of Schistosoma mansoni infectious to man, are covered by a single unit membrane and an immunogenic glycocalyx. When cercariae penetrate the host skin, they transform to schistosomula by shedding tails, secreting mucous and enzymes, and forming microvilli over their surface. Here the loss of the glycocalyx from cercariae transforming in vitro was studied morphologically and biochemically. By scanning electron microscopy, the glycocalyx was a dense mesh composed of 15-30 nm fibrils that obscured spines on the cercarial surface. The glycocalyx was absent on organisms fixed without osmium and was partially lost when parasites aggregated in their own secretions before fixation. By transmission electron microscopy, a 1-2 microns thick mesh of 8-15-nm fibrils was seen on parasites incubated with anti-schistosomal antibodies or fixed in aldehydes containing tannic acid or ruthenium red. Cercariae transformed to schistosomula when tails were removed mechanically and parasites were incubated in saline. Within 5 min of transformation, organisms synchronously formed microvilli which elongated to 3-5 microns by 20 min and then were shed. However, considerable fibrillar material remained adherent to the double unit membrane surface of schistosomula. For biochemical labeling, parasites were treated with eserine sulfate, which blocked cercarial swimming, secretion, infectivity, and transformation to schistosomula. Material labeled by periodate oxidation and NaB3H4 was on the surface as shown by autoradiography and had an apparent molecular weight of greater than 10(6) by chromatography. Periodate-NaB3H4 glycocalyx had an isoelectric point of 5.0 +/- 0.4 and was precipitable with anti-schistosomal antibodies. More than 60% of the radiolabeled glycocalyx was released into the medium by transforming parasites in 3 h and was recovered as high molecular weight material. Parasites labeled with periodate and fluorescein-thiosemicarbazide and then transformed had a corona of fluorescence containing microvilli, much of which was shed onto the slide. Material on cercariae labeled by lodogen-catalyzed iodination was also of high molecular weight and was antigenic. In conclusion, the cercarial glycocalyx appears to be composed of acidic high molecular weight fibrils which are antigenic and incompletely cleared during transformation.

Immunolocalization and characterization of the low molecular weight antigen (4–5 kDa) ofToxoplasma gondiithat elicits an early IgM response upon primary infection

Parasitology ◽  
1994 ◽  
Vol 108 (2) ◽  
pp. 139-145 ◽  
Author(s):  
S. Tomavo ◽  
G. Couvreur ◽  
M. A. Leriche ◽  
A. Sadak ◽  
A. Achbarou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Monoclonal Antibodies ◽  
Primary Infection ◽  
Low Molecular Weight ◽  
Immuno Electron Microscopy ◽  
Surface Localization

SUMMARYA striking feature of toxoplasmic seroconversion is the prominent and early IgM response to a low molecular weight antigen of 4–5 kDa. Two different monoclonal antibodies directed against the 4–5 kDa antigen have been generated and used to characterize this molecule. Using these monoclonal antibodies, we could demonstrate the surface localization of the lowMrantigen by immunofluorescence and immuno-electron microscopy assays. By immunoblotting, we observed that one of the monoclonal antibodies was unable to recognize the 4–5 kDa antigen in tachyzoites propagated in cell culture, indicating an epitope variability betweenToxoplasma gondiitachyzoites grownin vivoandin vitro. We discuss the implications of this latter finding in the design of diagnostic reagents.

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