Comparative Mucosal Microvasculature of the Mammalian Stomach

1989 ◽  
Vol 134 (1) ◽  
pp. 31-34 ◽  
Author(s):  
J. Marais ◽  
B.G. Anderson ◽  
W.D. Anderson
Keyword(s):  
Mammalian Stomach

scholarly journals Gastrobodies are engineered antibody mimetics resilient to pepsin and hydrochloric acid

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Niels Wicke ◽  
Mike R. Bedford ◽  
Mark Howarth
Keyword(s):  
Hydrochloric Acid ◽  
Computational Prediction ◽  
Scaffold Proteins ◽  
Gi Tract ◽  
Toxin B ◽  
Digestive Proteases ◽  
Mammalian Stomach ◽  
Phage Selection ◽  
Harsh Conditions ◽  
Selection Of

AbstractProtein-based targeting reagents, such as antibodies and non-antibody scaffold proteins, are rapidly inactivated in the upper gastrointestinal (GI) tract. Hydrochloric acid in gastric juice denatures proteins and activates pepsin, concentrations of which reach 1 mg/mL in the mammalian stomach. Two stable scaffold proteins (nanobody and nanofitin), previously developed to be protease-resistant, were completely digested in less than 10 min at 100-fold lower concentration of pepsin than found in the stomach. Here we present gastrobodies, a protein scaffold derived from Kunitz soybean trypsin inhibitor (SBTI). SBTI is highly resistant to the challenges of the upper GI tract, including digestive proteases, pH 2 and bile acids. Computational prediction of SBTI’s evolvability identified two nearby loops for randomization, to create a potential recognition surface which was experimentally validated by alanine scanning. We established display of SBTI on full-length pIII of M13 phage. Phage selection of gastrobody libraries against the glucosyltransferase domain of Clostridium difficile toxin B (GTD) identified hits with nanomolar affinity and enzyme inhibitory activity. Anti-GTD binders retained high stability to acid, digestive proteases and heat. Gastrobodies show resilience to exceptionally harsh conditions, which should provide a foundation for targeting and modulating function within the GI tract.

An Improved Staining of the Three Fundic Gland Cells of Mammalian Stomach

1961 ◽  
Vol 36 (4) ◽  
pp. 254-255 ◽  
Author(s):  
Hideo Tamate ◽  
Yo Kondo
Keyword(s):  
Fundic Gland ◽  
Gland Cells ◽  
Mammalian Stomach

Electrical Resistance of the Mammalian Stomach

1955 ◽  
Vol 181 (2) ◽  
pp. 451-470 ◽  
Author(s):  
Warren S. Rehm ◽  
Warren H. Dennis ◽  
Hilda Schlesinger
Keyword(s):  
Electrical Resistance ◽  
Mammalian Stomach

Osmotic flow of water in isolated frog gastric mucosa.

1979 ◽  
Vol 236 (1) ◽  
pp. E63
Author(s):  
R P Durbin
Keyword(s):  
Gastric Mucosa ◽  
Acid Production ◽  
Acid Output ◽  
Volume Flow ◽  
Osmotic Gradient ◽  
Apical Surface ◽  
Isotonic Solution ◽  
Mammalian Stomach ◽  
The Mean ◽  
Gravimetric Procedure

A gravimetric procedure was used to measure net volume flow across bullfrog gastric mucosa mounted between chambers. A portion of the net volume flow towards the lumen was coupled to acid production. With an isotonic solution instilled on the luminal surface, the secreted acidity (ratio of increase in acid output to increase in volume flow) was hypertonic, in agreement with previous reports in mammalian stomach. Dilution of the secretory solution to 10% of normal nearly abolished the net volume flow coupled to acid production so that the mean secreted acidity rose to 1.87 M. Other experiments in which gastric juice was collected from this preparation showed that secretion into an initially empty lumen was only slightly hypertonic, as in mammalian stomach. The results indicate that instillation of secretory solution dilutes the endogenous osmotic gradient due to secreted HC1. This gradient is probably just outside the apical surface of the oxyntic cells of stomach.

The ultrastructual morphology of the midgut diverticulum of the calanoid copepod Calanus helgolandicus (Claus) (Crustacea)

1970 ◽  
Vol 18 (1) ◽  
pp. 9 ◽  
Author(s):  
JE Ong ◽  
PS Lake
Keyword(s):  
Amino Acids ◽  
Epithelial Cells ◽  
Myoepithelial Cell ◽  
Calanoid Copepod ◽  
Apical Region ◽  
Basal Region ◽  
Epithelial Layer ◽  
Apical Half ◽  
Mammalian Stomach ◽  
Blue Reaction

The midgut diverticulum of the marine calanoid copepod C. helgolandicus consists of a columnar epithelial layer, a myoepithelial layer, and between these a well-developed basement membrane. The apical region of the epithelial cell is thrown into tightly packed microvilli which showed an alcian blue reaction indicating the presence of acid mucopolysaccharides. The apical half of the cell contains numerous microvesicles and mitochondria as well as tiny Golgi-like bodies. The plasma membrane of the basal region of the epithelium is extremely digitated. The digitations contain numerous mitochondria and the whole structure resembles mitochondrial pumps. The epithelial cells contain a large centrally situated oval nucleus with its single nucleolus. The myoepithelial cell is squamous and contains a flattened nucleus as well as very well-developed circularly and longitudinally arranged myofibrils. It is suggested that the midgut diverticulum of Calanus is probably analogous to the mammalian stomach in that food is mechanically churned. However, it does not appear to be involved in the secretion of digestive juices but only mucopolysaccharides; it is probably involved in the absorption of amino acids which are probably actively transported, by the "mitochondrial pump" in the basal region of the epithelial cells, into the haemocoel.

On exploring the basis for slow potential oscillations in the mammalian stomach and intestine

1979 ◽  
Vol 81 (1) ◽  
pp. 153-173
Author(s):  
J. A. Connor
Keyword(s):  
Action Potential ◽  
Electrical Activity ◽  
Slow Wave ◽  
Contractile Activity ◽  
Metabolic Processes ◽  
Slow Potential ◽  
Potential Oscillations ◽  
Mammalian Stomach

The basic driving unit of oscillatory electrical activity in stomach and intestine is the slow wave, a propagating depolarization of myogenic origin. The slow wave controls contractile activity in the intestine by triggering action potential bursts, while in the stomach there is both action potential and spike-free slow wave activation. This review attempts to summarize recent characterizations of the slow wave and to explore in detail the evidence, which suggests that the mechanisms which generate the electrical oscillations are quite closely coupled to metabolic processes.

scholarly journals Gastroduodenal HCO3(-) transport: characteristics and proposed role in acidity regulation and mucosal protection

1982 ◽  
Vol 242 (3) ◽  
pp. G183-G193 ◽  
Author(s):  
G. Flemstrom ◽  
A. Garner
Keyword(s):  
Acid Metabolism ◽  
Duodenal Mucosa ◽  
Unit Surface Area ◽  
Mucosal Protection ◽  
Inhibitory Peptide ◽  
Unit Surface ◽  
Mammalian Stomach ◽  
Dependent Transport

Gastric HCO3(-) transport (basal) studied in isolated amphibian mucosa and mammalian stomach in vivo amounts to 2-10% of maximal H+ secretion. Duodenal mucosa, devoid of Brunner's glands, transports HCO3(-) at a greater rate (per unit surface area) than either stomach or jejunum in vitro and in vivo. Gastric (but not duodenal) HCO3(-) transport is stimulated by dibutyryl cGMP, carbachol, and cholecystokinin and duodenal (but not gastric) transport by dibutyryl cAMP and gastric inhibitory peptide. Glucagon and E- and F-type prostaglandins stimulate, whereas histamine, gastrin, and secretin are without effect in both stomach and duodenum. Gastric transport very probably occurs by Cl--HCO3(-) exchange at the luminal membranes of the surface epithelial cells. In addition to this mechanism, the duodenum also transports HCO3(-) electrogenically. Lowering the luminal pH increases transport in both the stomach and duodenum. This response, probably mediated via both local production of prostaglandins and tissue-specific humoral agents, may be important in mucosal protection against acid. Metabolism-dependent transport of HCO3(-), stimulated by acid, seems quantitatively sufficient to account for all of the duodenal and most of the gastric mucosa's ability to remove luminal acid.

Na+ transport by mammalian stomach.

1978 ◽  
Vol 234 (3) ◽  
pp. E228 ◽  
Author(s):  
T E Machen ◽  
W Silen ◽  
J G Forte
Keyword(s):  
Short Circuit ◽  
Ph Effect ◽  
Normal Function ◽  
Open Circuit ◽  
Bathing Solution ◽  
Na Transport ◽  
In Vitro Investigation ◽  
Mammalian Stomach

Gastric mucosas from newborn pigs (0--20 days) and rabbits (0--20 days) were used for in vitro investigation of active Na+ transport during resting (no HCl secretion) conditions. As measured with 22Na+, these tissues actively absorb Na+ from the mucosal-to serosal (m-t-s) bathing solution during both open-circuit and short-circuit current (Is) conditions. In the nonsecreting state, net Na+ transport accounts for 40--60% of Isc. The remaining current is provided by net s-to-m flux of Cl-. Amiloride (2-5 X 10(-5) M) in the mucosal solution abolishes this active Na+ transport by inhibiting m-to-s fluxes of Na+ (JNams). In vivo-in vitro experiments showed that active Na+ transport is a normal function of the resting mammalian stomach. Decreasing pH of the mucosal solution below pH 5 reversibly causes decreased current-generating capability of the tissue. Pretreatment of the tissue with amiloride abolishes this pH effect. The implication is that the low pH affects the Na+-entry step into cells. "Titration curves" of current vs. pH had an apparent pK approximately 4.0. Ouabain and K+-free solutions both cause decreases in active Na+ and Cl- current. Calculations indicate that a shunt may account for only a small (less than 30%) percentage of total transepithelial conductance.

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