Gonococcal keratoconjunctivitis in adults JS Lee et al 646Eye her knees and loose-jointedness. Her vision was 6/4 bilaterally, without any angioid streaks. His son had stiff joints except his knees, extensible skin over the neck and face and a normal ocular examination. It was felt that our case was a PXE heterozygote and that angioid streaks were part of this clinical phenotype. In the absence of cutaneous changes homozygosity for the PXE gene is unlikely, although it cannot be totally excluded. DNA has been extracted and banked to test for the PXE gene in the future. A formal skin biopsy from the side of the neck showed minimal elastotic degeneration and elastic fibres were not Von Kossa positive. There were no particular features suggestive of PXE. The recent normal colonoscopy rules out Familial Adenomatous Polyposis (FAP). CommentCongenital hypertrophy of the retinal pigment epithelium (CHRPE) is a well-known association of Familial Adenomatous Polyposis (FAP). On reviewing literature there is one case report of a middle-aged Caucasian male with angioid streaks but no CHRPE who had extensive FAP. 4 The relationship between CHRPE and angioid streaks is probably coincidental and has not been reported before. The previously reported case had extensive FAP necessitating a total colectomy, though his fundi did not show any features of CHRPE. Both these patients were Caucasian males, of similar age and with radiological evidence of degenerative changes in their lumbar vertebrae. The striking similarity between these cases and the fact that CHRPE and FAP often are part of the same syndrome suggests that their relationship with angioid streaks could be part of the same syndrome. In the present case the cutaneous manifestations of PXE were minimal, while in the previously reported case FAP was not associated with CHRPE, possibly indicating an incomplete expression. References

Transport of [14C]tetraethylammonium (TEA), an organic cation, was studied in brush-border (BBMV) and basolateral (BLMV) membrane vesicles isolated from rabbit kidney cortex. In BBMV, the presence of an outwardly directed H+ gradient induced a marked stimulation of TEA uptake against its concentration gradient (overshoot phenomenon), whereas a valinomycin-induced inside-negative potential had no effect on TEA uptake. In BLMV, TEA uptake was significantly stimulated by the presence of an outwardly directed H+ gradient and by an inside-negative potential, but the effect of H+ gradient was absent when the vesicles were chemically 'voltage clamped'. In BBMV, internal H+ stimulated TEA uptake in a non-competitive manner by binding at a site with apparent pKa of 6.87. External H+ inhibited TEA uptake through a direct interaction with the putative H+/organic-cation exchanger at a site with apparent pKa of 6.78. Changing external pH while maintaining the pH gradient constant produced a result similar to that obtained by changing external pH alone. Increasing external H+ showed a mixed-type inhibition of TEA uptake. These results suggest that in the rabbit TEA transport across the basolateral membranes is driven by an inside-negative potential and that transport across the brush-border membrane is driven by a H+ gradient via an electroneutral H+/TEA antiport system.

Stripped rabbit descending colon mucosae were studied in vitro in modified Ussing chambers to determine the effects of AlF4- and vanadate on Cl- transport. Serosal additions of AlF4- and vanadate increase short circuit current (Isc) and tissue conductance, while luminal addition of the agents is ineffective. Addition of aluminium potentiates the effect of NaF on Isc. AlF4- and vanadate increase serosal-to-mucosal flux of 36Cl without affecting mucosal-to-serosal flux. The effects of these agents on Isc are markedly inhibited by serosal addition of bumetanide and depend on the presence of Na+ in the serosal bathing solution. The effects of AlF4- and vanadate on Isc are dependent on the presence of Ca2+ in the bathing solution, and are completely inhibited by indomethacin, but the effect of forskolin is not affected by the removal of Ca2+ from the bathing solution and the addition of indomethacin. AlF4- and vanadate significantly increase the level of inositol phosphate metabolites. The results indicate that AlF4- and vanadate increase Cl- secretion in the rabbit colon via an increase in prostaglandin synthesis which is mediated by the increase of intracellular Ca2+ concentrations.

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