A model for transepithelial ion transport across the isolated retinal pigment epithelium of the frog

The contribution of chloride ion movement and sodium and bicarbonate concentrations to the net current across the isolated choroid-retinal pigment epithelium (RPE) of the bullfrog were studied. The presence of a ouabain-sensitive Na+/K+-pump on the retinal side was confirmed and complete inhibition of this pump with Na+ removal and ouabain treatment abolished nearly all the RPE transepithelial transport and SCC suggesting that all ionic transport was dependent on sodium. It was found that apical to basal (AB) chloride flux accounted for 26 +/- 2% (mean +/- S.E.M.) of the short circuit (SCC). Results suggest that AB bicarbonate and/or basal to apical (BA) hydrogen ion net transport accounts for 38 +/- 2% of the SCC while BA sodium is presumably responsible for the remaining 34% of the SCC. Transport was inhibited by apical administration of known chloride inhibitors. Trans-RPE 36Cl flux measurements indicate that furosemide (10(-4) M) and SITS (10(-3) ) decrease the retinal-choroid flux. Results suggest that net transport of chloride and bicarbonate are independent of each other and additive. It was found that a bicarbonate-free preparation was relatively unaffected by changes in pH (5.5-8.5) indicating that pH has little, if any, effect on sodium or chloride current in this range. A model is presented which is compatible with the various data. It is suggested that along with the apical Na+/K+-ATPase pump, there exists an apical Na+/Cl- -co-transport system which is driven by the established sodium gradient. Moreover, this pump established sodium gradient is postulated to drive a Na+/HCO3- -co-transport system tentatively placed on the retinal side of the RPE.     

Hereditary coproporphyria and epilepsy

A 9-year-old boy with mental deterioration and epilepsy suffered an acute attack of hereditary coproporphyria associated with worsening of seizure control. Leucocyte coproporphyrinogen oxidase activity was undetectable in the patient during this attack, and was reduced in his mother, a latent case. The complex relationship between porphyria, epilepsy, and anticonvulsant drugs is discussed.     

Acquired malposition of the colon and gallbladder in patients with cirrhosis: CT findings and clinical implications

Topographic relationships among the gallbladder, liver, hepatic flexure of the colon, right hemidiaphragm, and anterolateral peritoneal reflection were evaluated with computed tomography in 75 patients with biopsy-proved cirrhosis and in 200 control subjects to determine the effect of cirrhotic liver morphology on the anatomy of the right upper quadrant of the abdomen. Interposition of the colon between the liver and anterolateral abdominal wall and/or diaphragm was seen in 18 of the 75 (24%) cirrhotic patients and in six of the 200 (3%) control subjects. There was a strong correlation among gallbladder malposition, colonic interposition, and a ratio of transverse caudate lobe width to right lobe width (C/RL) exceeding 0.60. Patients with cirrhosis, colonic interposition, and gallbladder malposition had a mean C/RL of 0.62, compared with a mean of 0.50 for cirrhotic patients without interposition (P less than .0001). The mean C/RL for control subjects without interposition was 0.43, as compared with 0.69 for control subjects with interposition (P less than .01). These acquired malpositions of the colon and gallbladder may pose a diagnostic dilemma and increase the risk of inadvertent injury during percutaneous liver biopsy, interventional biliary tract procedures, and laparotomy.     

Normal instability of the hip in the neonate: US standards

In recent years, the use of real-time ultrasonography (US) has enabled dynamic evaluation of the infant hip through a range of motion and stress. Preliminary experience has suggested that a certain amount of instability in the hips of newborns is normal, but no standards have been established. In this study, a group of term neonates whose physical examinations were normal were examined with US on the 1st and 2d days of life. Each hip was imaged in the transverse plane in nonstressed and stressed positions, and movement of the femoral head under stress was quantitated. This displacement under stress was used to establish a normal range of hip instability in neonates. Patterns of hip laxity in boys and girls are identical, and in most infants hip instability diminishes between the 1st and 2d days of life. Our method of quantitating hip instability produces consistent results, with intraobserver 95% confidence intervals of +/- 1.2 mm for each measurement.