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Biomedical subjects

D Fromm

Publications and source records attributed to D Fromm.

35 records · Page 2Linked to original sources
PubMed1976

Attempted retrograde cannulation of the ampulla: a probable cause of mass in the pancreas.

Two patients developed a focal mass in the head of the pancreas presumably following attempted endoscopic retrograde cholangiopancreatography (ERCP). These lesions grossly mimicked carcinomas of the pancreas. In one case a radical pancreatoduodenectomy was performed because of the misleading gross findings. A focal mass in the pancreas following ERCP may develop due to asymptomatic pancreatitis caused by the procedure.

Aged↗
PubMed1976

Effects of salicylate and bile salt on ion transport by isolated gastric mucosa of the rabbit.

The effects of luminal addition of salicylate and taurocholate on ion transport by fundic mucosa were examined in vitro using isotopic and pH stat techniques. Salicylate, 3 mM, did not alter, but 20 mM caused a 40% decrease in, the acid secretory rate. Taurocholate, 20 mM, caused a transient, apparent cessation of acid secretion followed by stimulation. Salicylate, 3 or 20 mM, increased Na+ but not Cl- permeability at luminal pH 7. At luminal pH 4, however, salicylate increased Cl- in addition to Na+ and H+ permeability. Taurocholate, 10 or 20 mM, increased both cation and anion permeability at pH 7 and 4. Addition of salicylate or taurocholate results in stimulation of net Na+ transport. While salicylate and taurocholate increase cation permeability at pH 7, they have differing effects on acid secretion and anion permeability. The data suggest that salicylate and taurocholate alter cation permeability by different mechanisms and are consistent with the concept that enhanced diffusion of H+ into the tissue causes a nonspecific alteration in the permeability pathway.

Animals↗
PubMed1976

Ion transport across isolated antral mucosa of the rabbit.

Isotopic fluxes of Na, Cl, and K were measured across isolated antral mucosa under short-circuit conditions. HCO3 fluxes were also measured with either isotopic and/or pH-stat methods. Net secretion of all four ions was observed. HCO3 secretion is due to a transmural process requiring metabolic energy. Secretion of endogenous HCO3 was not observed, and the unidirectional mucosal-to-serosal flux of HCO3 was negligible. There appears to be a close relationship between HCO3 secretion and the unidirectional mucosal-to-serosal Cl flux, but not relationships were observed between the unidirectional serosal-to-mucosal flux or either unidirectional Na flux. The bulk of HCO3 secretion is independent of the unidirectional Cl fluxes, but there is a fraction of HCO3 transport that is dependent on unidirectional Cl transport. However, HCO3 transport is not measurably influenced by inhibition of net Cl (and Na) transport per se.

Acetylcholine↗
PubMed1976

Effects of alcohol on ion transport by isolated gastric and esophageal mucosa.

The effects of ethyl alcohol, 20%, were measured on steady state rates of ion transport by isolated mucosa. Luminal, but not serosal, addition of alcohol altered ion transport. Alcohol caused a sustained reduction in apparent basal acid secretion by fundic mucosa. These tissues were resistant to ordinarily effective stimulants of acid secretion (histamine, theophyline, dibutyryl cyclic AMP, and gastrin) by rabbit mucosa. Across antral mucosa, net Na transport was inhibited, and net Cl transport was reduced in the presence of alcohol. The unidirectional fluxes of both ions were increased as was permeability to erythritol. These effects of alcohol did not require the presence of acid in the lumen. The rate of luminal acid loss by antrum was increased by alcohol. Addition of ouabain alone, which inhibits net Na and Cl transport, did not alter the rate of luminal acid loss by antrum. Alcohol, however, still increased the rate of luminal acid loss by antral mucosa treated with ouabain. Alcohol reduced the electrical resistance of fundic and antral mucosa but had no effect on the rate of luminal acid loss or electrical resistance of esophageal mucosa. Luminal application of alcohol inhibits active ion transport in addition to increasing cation and anion permeability. However, inhibition of active transport per se is not necessarily associated with an increase in mucosal permeability.

Animals↗
PubMed1976

Histamine effects on H+ permeability by isolated gastric mucosa.

This study examines the effects of histamine on mucosal permeability to acid by isolated stomach of rabbits. Histamine (9 X 10(-5) M) decreased antral luminal acid loss which could not be accounted for by active H+ secretion or appearance of organic acid. Histamine also increased antral electrical resistance and decreased the unidirectional luminal to serosal flux (Jls) of (14)c-erythritol. Histamine, theophylline, and N(6),O(2)-dibutyryl adenosine 3',5'-monophosphate did not significantly alter secretion by fundus in the presence of salicylate (5 X 10(-3)M). However, after removal of salicylate, these agents stimulated acid secretion. Histamine decreased luminal acid loss by both antrum and fundus treated with salicylate, increased the electrical resistance of these tissues, and decreased Jls erythritol of fundic mucosa. Burimamide (1 X 10(-3) M) inhibited the permeability effects of histamine on antrum and fundus. The data indicate that histamine decreases spontaneous antral mucosal permeability as well as salicylate-induced increase in mucosal permeability of both antrum and fundus. The effects of burimamide suggest that antrum contains H2 receptor sites urelated to acid secretion and that fundus contains H2 receptor sites which also govern permeability but are independent of those related to acid secretion.

Animals↗
PubMed1976

Ion selective effects of salicylate on antral mucosa.

The effects of luminal salicylate, 5mM, were measured on rates of ion transport by isolated antral mucosa. At neutral luminal pH, salicylate increases Na and decreases Cl permeability. Salicylate does not alter net Na transport but decreases net Cl secretion. At luminal pH 4, the effects of salicylate can be arbitrarily divided into two phases. The intitial phase is associated with an increase in Na and marked decrease in Cl permeability. Subsequently, a greater increase in Na permeability and a marked increase in Cl permeability occurs. Active Na transport persists in the presence of salicylate at pH 4. Indirect evidence also suggests that Cl secretion persists under these conditions, buy at a reduced rate. The rate of luminal acid acid loss also increases in the presence of salicylate. A 4-fold increase in salicylate concentration or decrease in luminal pH from 4 to 3 did not appear to intensify the effects observed for 5 mM salicylate at pH 4. The increase in cation and decrease in anion permeability observed at pH 7 and initially at pH 4 are compatible with an influence of a negative charge of the salicylate anion. The subsequent changes observed in the presence of acid also are compatible with the concept that as the mucosa becomes overwhelmed with acid, a nonspecific increase in permeability occurs. However, the effect of salicylate on active Cl transport is largely independent of acid diffusing into the mucosa.

Animals↗
PubMed1975

Ion transport by rabbit jejunum in vivo.

Net ion and H2O transport by jejunum adjacent to the ligament of Treitz (proximal jejunum) and midjejunum were measured in vivo by continuous perfusion with HCO3-Ringer solution containing a volume marker. Proximal jejunum secreted Na and H2O, whereas midjejunum absorbed Na and H2O. Both segments secreted CO2 and absorbed K and Cl. D-glucose stimulated absorption of Na and H2O and the transmural electrical potential difference (PD) in both segments, but these changes were not accompanied by alterations in Cl, CO2, or K fluxes. However, the increse in Na absorption caused by 3-O-methylglucose was matched by an increase in Cl absorption. This, in addition to increased tissue lactate concentration after addition of D-glucose, suggests that organic anion maintains electroneutrality for Na transport enhanced by D-glucose. Cholera toxin had no effect on ion transport or PD in proximal jejunum, but cholera toxin stimulated secretion and increased the PD in more distal jejunum. Although proximal jejunum shows spontaneous secretory activity, its capacity for secretion is not as great as more distal small intestine.

Animals↗
PubMed1975

Transport of H plus and other electrolytes across isolated gastric mucosa of the rabbit.

The relationship of transmural and cellular phenomena to the rate of spontaneous luminal HH+ secretion by short-circuited gastric mucosa bathed in HCO3- and CO2-free Ringer solution was studied by the pH-stat technique. The bulk of luminal acidification can be accounted for by the appearance of H+ and not by organic acids. Acid secretion requires the presence of O2 and exogenous substrate but is not limited by endogenous CO2 production. The rate of H+ secretion is matched by the serosal appearance of alkali. The greater appearance of CO2 on the serosal side of the mucosa is consistent with hydroxylation of CO2 and greater permeability of the serosal border to HCO3-. Luminal changes in H+ concentrations affect H+ secretion but serosal changes do not, suggesting that the gradient produced by H+ secretion is at the luminal border. Steady-state isotopic Na+ and Cl- fluxes indicate net secretion of both ions, but net K+ transport is negligible.

Animals↗
PubMed1975

Effects of theophylline on Na and alanine transport across isolated rabbit ileum.

Addition of theophylline to isolated rabbit ileal mucosa resulted in a persistent increase in short-circuit current (SCC) and a persistent decrease in DC conductance. Under short-circuit condition, net Na flux (JNanet) was reversed by theophylline from absorption to secretion (-0.6 mueq/h cm2) and was due to a decrease in unidirectional mucosal- (M) toserosal (S) flux (JNams). Addition of L-alanine to theophylline-treated m-ucosa increased SCC, JNanet, and JNams. Theophylline reduced JAlanet by 25%. Na flux ratios, determined in the presence of theophylline at +26 and -11 mV (mucosal reference), differed from flux ratios expected for a diffusional process by less than 8%. In contrast, Na flux ratios, determined in the absence of theophylline and presence of glucose at +26 and O mV, differed from diffusional ratios by 35%. The results are consistent with the hypothesis that theophylline inhibits active Na absorption, but the data do not conclusively demonstrate the diffusional nature of unidirectional Na fluxes in the presence of theophylline.

Alanine↗
PubMed1975

Effects of cyclic adenosine 3':5'-monophosphate and related agents on acid secretion by isolated rabbit gastric mucosa.

The effects of various adenosine phosphate compounds, theophylline, histamine,a nd metiamide, on steady rates of acid secretion by isolated fundic mucosa of the rabbit were measured by the pH stat method. Cyclic adenosine 3':5'-monophosphate (cyclic AMP), N(6), O(2')-dibutyryl adenosine 3':5'-monophosphate and theophylline increased the rate of acid secretion. Addition of theophylline in a concentration which has no stimulatory effect, reduces the effective concentrations cyclic AMP or histamine required for stimulation of acid secretion. Measurements of lactate, pyruvate, and CO2 appearances indicated that the increases in acid secretory rates were predominantly due to H+ and not organic acid accumulation in the luminal bath-secretion. Metiamide prevented the stimulatory effects of histamine and ATP. However, metiamide did not prevent the stimulatory effects of N(6),9(2')-dibutyryl adenosine 3':5'-monophosphate, theophylline, or 5'-AMP. The results provide further evidence for a role of cyclic AMP in governing the rate of acid secretion by rabbit stomach. The data also are consistent with histamine and ATP (at least in the concentration used) requiring adenylate cyclase activity for stimulation of acid secretion and 5'-AMP inhibiting phosphodiesterase activity.

Adenosine Monophosphate↗