Ri. Henkin et al., Efficacy of exogenous oral zinc in treatment of patients with carbonic anhydrase VI deficiency, AM J MED SC, 318(6), 1999, pp. 392-405
Citations number
171
Language
INGLESE
art.tipo
Article
Categorie Soggetti
General & Internal Medicine","Medical Research General Topics
Background: We previously described a disorder in 18 patients with decrease
d parotid saliva gustin/carbonic anhydrase (CA) VI secretion associated wit
h loss of taste (hypogeusia) and smell (hyposmia) and distorted taste (dysg
eusia) and smell (dysosmia). Because gustin/CAVI is a zinc-dependent enzyme
we instituted a study of treatment with exogenous zinc to attempt to stimu
late synthesis/secretion of gustin/CAVI and thereby attempt to correct the
symptoms of this disorder. Methods: Fourteen of the 18 patients with this d
isorder completed the study. They were treated with 100 mg of exogenous zin
c daily for 4 to 6 months, in an open clinical trial. Both before and after
treatment, measurements were obtained of parotid saliva gustin/CAVI, parot
id saliva, serum and urine zinc, taste and smell function, and, in some pat
ients, examination of circumvallate taste buds by electron microscopy. Resu
lts: Treatment success was predicated upon significant increases in parotid
saliva gustin/CAVI. This occurred in 10 of the 14 patients who were labele
d responders; they also exhibited improvement in taste and smell acuity, a
diminution in dysgeusia and dysosmia and increased zinc concentrations in p
arotid saliva, serum, and urine. Taste bud morphology returned to normal in
each responder in whom it was measured. No increase in gustin/CAVI occurre
d in 4 patients who were labeled nonresponders; they exhibited no improveme
nt in taste or smell acuity and no increases in parotid saliva zinc. Howeve
r, serum and urine zinc increased to levels similar to those measured in th
e 10 responders. Two of 4 nonresponders reported diminution in dysgeusia an
d dysosmia. Taste bud morphology did not change from the abnormal state in
the 1 nonresponder in whom it was measured. Conclusions: Zinc treatment is
effective in patients in whom this trace metal increases synthesis/secretio
n of gustin/CAVI and ineffective in those in whom it does not. Increased gu
stin/CAVI in this disorder is probably associated with zinc stimulation of
the gene responsible for the synthesis/secretion of gustin/CAVI. Among nonr
esponders, zinc was ineffective for several possible reasons, including res
istance to zinc and possible sialylation of gustin/CAVI, which may render i
t functionally ineffective. Results suggest the hypothesis that gustin/CAVI
is a trophic factor that promotes growth and development of taste buds thr
ough its action on taste bud stem cells.