Search PubMed⌕ Search

Biomedical subjects

J F White

Publications and source records attributed to J F White.

At least 91 records · Page 5Linked to original sources
PubMed1981

Recurrent laryngeal nerve section in the treatment of spastic dysphonia.

Spastic dysphonia is a severe vocal disability in which the patient speaks with hyperadducted vocal folds. The resulting abnormality is characterized by excessively low pitch, vocal tremor, laryngospasms, and strain-strangle voice quality. Until recently the disorder was regarded as psychogenic and treated unsuccessfully with speech therapy and psychotherapy. New evidence supports the theory that the etiology is neurologic, requiring management designed to alter neurophysiologic function. Section of the recurrent laryngeal nerve provides immediate results and a new voice virtually free of the previous unpleasant characteristics.

Adult↗
PubMed1981

Intestinal bicarbonate secretion in Amphiuma measured by pH stat in vitro: relationship with metabolism and transport of sodium and chloride ions.

1. Isolated Amphiuma small intestine exposed on both surfaces to buffered or unbuffered media generated gradients of pH under short-circuited conditions consistent with secretion of HCO3(-). 2. When unbuffered mucosal medium was maintained at pH 7.4 by addition of acid, alkalinization of the mucosal medium occurred at a rate of 1-2 microequiv/hr cm2 under short-circuit conditions (Isc) and was reduced by anoxia, acetazolamide or removal of CO2. 3. The rate of HCO3(-) secretion (JHCO3(-)) was reduced at a mucosal pH above or below 7.4 and was proportional to serosal HCO3(-). 4. JHCO3(-) was reduced in Na+-free (choline) and Cl-free (SO4(2-) media and after exposure to the stilbene SITS. 5. The difference JHCO3(-)--Isc was consistent with net Cl- absorption. 6. The tissue resistance (Rt) was elevated upon exposure to serosal HCO3(-) and lowered by mucosal HCO3(-). 7. The intestinal mucosa exhibited carbonic anhydrase activity that was sensitive to ethoxazolamide. 8. It is concluded that HCO3(-) secretion is active, influenced by intracellular carbonic anhydrase activity and coupled to Cl- and possibly Na+ absorption.

Animals↗
PubMed1981

Chloride transport and intracellular chloride activity in the presence of theophylline in Amphiuma small intestine.

1. Simultaneous bidirectional tracer fluxes of 22Na and 36Cl were measured under short-circuited conditions in isolated stripped segments of Amphiuma duodenum incubated in media containing Cl- and HCO3-. 2. Theophylline (10 mM) increased the short-circuit current (Isc), eliminated net Cl- absorption and elevated the residual flux by more than 50%. 3. Subsequent addition to acetazolamide lowered the Isc and reduced the residual flux. 4. Using double-barreled Cl- specific micro-electrodes the intracellular activity of Cl- averaged 27.1 mM in the presence of theophylline, consistent with active accumulation of Cl-. 5. Theophylline depolarized the mucosal membrane of villus epithelial cells by an average of 6.9 mV. 6. The findings indicate that the inhibition of Cl- absorption by theophylline does not result from complete inhibition of mucosal Cl- uptake and provide evidence that HCO3- secretion is enhanced by theophylline.

Acetazolamide↗
PubMed1981

The effect of theophylline on intestinal bicarbonate transport measured by pH stat in Amphiuma.

1. The influence of theophylline on the mucosa to serosa and serosa to mucosa fluxes of HCO3- were measured by the pH stat technique in isolated segments of proximal small intestine from Amphiuma maintained under short-circuited conditions. The mucosal or serosal fluid was exposed to media containing 25 mM-HCO3- (pH 7.4) while the pH of unbuffered media in the opposite compartment was maintained by addition of acid. 2. Theophylline significantly increased the secretory flux of HCO3- and significantly reduced the absorptive flux when measured in Cl- -free (SO4(2-)) media. 3. In normal media theophylline did not alter the secretory flux but significantly lowered the absorptive flux of HCO3-. 4. Acetazolamide (0.1 mM) inhibited the theophylline-stimulated secretory flux of HCO3- and reduced the effect of theophylline on the absorptive flux. 5. In normal intestine there was an inequality between the secretory or absorptive HCO3- flux and the short-circuit current (Isc) consistent with the presence of Cl- absorption. After addition of theophylline the Isc was more nearly equal to the net secretory or absorptive HCO3- flux. 6. Exogenous cyclic AMP had effects identical with theophylline. 7. The results provide strong evidence that elevation of cyclic AMP stimulates net HCO3- secretion in urodele small intestine and provide indirect evidence that Cl- absorption is simultaneously reduced.

Acetazolamide↗
PubMed1981

Bicarbonate absorption by in vitro amphibian small intestine.

Isolated segments of jejunum from Amphiuma bathed in Cl--free (SO42(-)) media usually generated serosa-negative electrical potentials when HCO3(-) was present in the media. Bidirectional isotope fluxes under short circuit revealed a negligible absorption of Na+ and a residual flux consistent with anion absorption. Acetazolamide (10(-4) M) eliminated the short-circuit current and the residual flux. Segments of jejunum exposed on the mucosal surface to HCO3(-) (pH 7.4) alkalinized the unbuffered serosal fluid at a rate of about 1.1 mueq . h-1 . cm-2, as measured by the pH-stat while clamped at zero transepithelial potential. Acetazolamide, anoxia, and 2,4-dinitrophenol lowered the rate of alkalinization and simultaneously reduced the short-circuit current by an equal amount. Absorption was constant above a [HCO3(-)] of 35 meq/l and uninfluenced by applied transepithelial voltage gradients. HCO3(-) absorption was not reduced after replacement of media Na+ or Cl- but was reduced on addition of ouabain or removal of K+. It is concluded that the jejunum actively absorbs HCO3(-) by an electrogenic process that does not involve Na+-H+ exchange.

Acetazolamide↗
PubMed1980

Membrane potentials and chloride activities in epithelial cells of Aplysia intestine.

Microelectrodes were used to measure the potential difference across the mucosal membrane (psi m) of cells lining the mucosa of isolated Aplysia californica intestine. In glucose-free sodium chloride seawater medium psi m was -68.2 +/- 2.2 mV, the cell interior negative relative to the mucosal bathing medium. Simultaneously, the transmural potential difference (psi m leads to s) was recorded and its value averaged -0.4 +/- 0.1 mV (serosa negative). The addition of D-glucose to the mucosal compartment depolarized psi m to -62.1 +/0 2.5 mV and hyperpolarized psi m leads to s to -1.5 +/- 9.1 mV. Intracellular chloride activity (aCli) was also determined in Aplysia intestinal cells using single-barreled ion-exchange microelectrodes. In the absence of D-glucose the mean aCli was 10.1 +/- 0.5 mM, whereas after mucosal glucose addition the paired mean aCli increased significantly to 14.2 +/- 0.6 mM. Both aCli values were less than those predicted by the electrochemical equilibrium for chloride across the mucosal membrane. An active chloride transport mechanism located in the lateral-serosal membrane of the surface epithelial cells is proposed to explain these observations.

Animals↗
PubMed1979

Contribution of villus and intervillus epithelium to intestinal transmural potential difference and response to theophylline and sugar.

A chamber design is described which permits isolation of villus or intervillus epithelium from proximal segments of Amphiuma intestine and measurement of the transpithelial potential difference (psi ms) and short-circuit current (Isc) produced by each. In media containing Cl- and 10 mequiv./l HCO3- the villus generated a basal psi ms of 0.8 mV (serosa negative) and Isc of 12 microA/cm2 while the intervillus psi ms and Isc were not different from zero. Acetazolamide altered the villus psi ms by 1.2 mV; the intervillus psi ms by only 0.3 mV. Transepithelial gradients of HCO3- appeared to generate diffusion potentials across the intervillus but not the villus epithelium. The actively transported sugar galactose elevated psi ms by 0.6 +/- 0.1 mV in the intervillus epithelium and by 1.5 +/- 0.2 mV in the villus epithelium for a response ratio (0.6/1.5) = 0.4. The response ratio for valine was 0.3. In contrast, the response ratios for theophylline (0.7) and cyclic AMP (0.7) were significantly higher. These observations indicate that the entire epithelium is responsive to theophylline and cyclic AMP while Na+-dependent solute transport and the basal electrogenic ion transport processes are primarily functions of the cells lining the intestinal villus.

Animals↗
PubMed1979

Response of Amphiuma small intestine to theophylline: effect on bicarbonate transport.

The electrolyte transport properties of isolated proximal segments of Amphiuma small intestine and their response to theophylline were observed under various conditions. In the absence of theophylline the intestine generates a transepithelial potential (psi ms) serosa negative to mucosa when Cl- and HCO3- are present in the bath. Replacement of Cl- or HCO3- reduced the magnitude and usually reversed the sign of psi ms. Acetazolamide (10(-4) M) nearly abolished the serosa negative psi ms. Theophylline (10 mM) drove psi ms serosa positive, the magnitude depending on the bath Na+ and HCO3- concentrations. Simultaneously it increased the short-circuit current (Isc) and tissue resistance (Rt). The increase in Isc was not due to increase net Na+ transport in Cl-free buffer and was attributed to a residual ion flux. Acetazolamide reduced the Isc, Rt, and the net residual flux observed in theophylline-treated intestine. The magnitude of the acetazolamine effect on Isc was proportional to the Na+ and HCO3- concentrations of the bath. The results suggest that in the absence of theophylline, HCO3-, and Cl- transport are related. Furthermore, acetazolamide inhibits the movement of an ion, possibly HCO3-, secreted in response to theophylline.

Acetazolamide↗
PubMed1978

Evidence for the existence of an agent in the serum of the cyclic hematopoietic dog which influences hemoglobin synthesis.

Serum samples collected through the cycle of a cyclic hematopoietic (CH) dog under reduced atmospheric conditions, were assayed for their ability to affect hemoglobin synthesis by normal canine bone marrow. Varying levels of hemoglobin synthesis in the presence of different serum samples suggest an agent cycles in the serum of CH dogs which influences hemoglobin synthesis.

Animals↗
PubMed1977

Alterations in electrophysiology of isolated amphibian small intestine produced by removing the muscle layers.

Isolated segments of Amphiuma small intestine bathed in chloride or sulfate buffer generate a greater short-circuit current and a larger change in current in response to galactose when the serosal muscle layers are stripped from the mucosa. Intact (unstripped) segments are not apparently anoxic since stripped segments exposed to serosal N2 for 3 h display normal short-circuit currents but a reduced potential response to galactose, while the presence of muscle layers tends to reduce the short-circuit current but does not alter the potential response to galactose. Bullfrog small intestine also generates greater short-circuit current following removal of the muscle layers. The enhancing effect of stripping appears to be related to removal of a resistance to ion flow across the tissue.

Amphibians↗
PubMed1977

Cardiac arrest temperature: the effect of ethyl alcohol and carbon dioxide on baboons.

The effect of high inspired carbon dioxide concentrations and i.v. ethyl alcohol on the temperature at which cardiac arrest occurred was studied in chacma baboons. Alcohol-treated baboons developed cardiac arrest at a temperature of 24.3 degrees C (SD +/- 0.85) and control animals at 27 degrees C (SD +/- 1.30). There were no signs of cardiac failure before the occurrence of ventricular fibrillation.

Animals↗
PubMed1977

Activity of chloride in absorptive cells of Amphiuma small intestine.

Double-barreled chloride-selective microelectrodes constructed by a new method have been used to determine intracellular chloride activity (aic1) in the absorptive cells of isolated, stripped proximal and distal segments of Amphiuma small intestine. Chloride was passively distributed across the mucosal membrane in fall and winter animals and aic1 is about 20 mM. In contrast summer animals actively accumulated chloride in both proximal and distal segments. Parallel measurements of intracellular chloride concentration (Cic1) reveal a very low apparent chloride activity coefficient (aic1/CiC1) indicating that all of the chloride is not free in the cytoplasm. The chloride activity in the bath immediately adjacent to the mucosa is higher than in the bulk solution.

Amphibians↗