Prevalence and risk factors of smell dysfunction - a comparison between five German population-based studies

BACKGROUND

The prevalence of olfactory impairment increases with age and is known to be an early sign of different neurodegenerative diseases. Only few population-based studies examined the prevalence of olfactory impairment and comparisons across studies are scarce. Aim of this analysis was to compare the prevalence and determinants of normosmia across five population based studies in Germany.

METHODOLOGY

Data from five population-based, cross-sectional studies were included. They were independently conducted and used the same test system (Sniffin' Sticks Screening 12) to measure olfactory function. This system consists of 12 odor-dispensing felt-tip pens; the task is a forced-choice selection among four alternative odors per pen. Sociodemographic information and comorbidities were assessed in face-to-face interviews. Univariate, descriptive statistics and multivariable logistic regression models stratified by study, were performed to determine risks, i.e. prevalence odds ratios, associated with olfactory function.

RESULTS

The prevalence of normosmic participants varied considerably across studies. Olfactory function was lower in men, decreased with age, and increased with higher education. Several individual comorbidities and a comorbidity index were associated with olfactory dysfunction. Recognition performance for three of the 12 pens was especially low in all studies.

CONCLUSION

Four factors, well known to describe population composition, contribute to explain differences in the prevalence of olfactory function between studies when the same test system is used. Our results indicate that comorbidities and educational level should always be considered when test systems based on smell recognition are used in population-based studies.

Detection and location of the enzymes of de novo pyrimidine biosynthesis in mammalian spermatozoa

Enzymes of the pathway for de novo biosynthesis of pyrimidine nucleotides have been reported in spermatozoa from fruitfly and mammals. The aim of the present study was to test the hypothesis that the enzymes for biosynthesis of uridine monophosphate (UMP) are concentrated near the mitochondria, which are segregated in the mid-piece of spermatozoa. Baby hamster kidney fibroblasts were compared with spermatozoa from rams, boars, bulls and men. Antibodies raised against synthetic peptides from sequences of the multienzyme polypeptides containing glutamine-dependent carbamyl phosphate synthetase, aspartate transcarbamylase and dihydroorotase (CAD) and UMP synthase, which catalyse reactions 1-3 and 5-6, respectively, were used, together with an affinity-purified antibody raised against dihydroorotate dehydrogenase (DHODH), the mitochondrial enzyme for step 4. Western blot analysis, immunofluorescent microscopy and immunoelectron microscopy confirmed that CAD and UMP synthase are found in the cytoplasm around and outside the mitochondria; DHODH is found exclusively inside the mitochondria. CAD was also located in the nucleus, where it has been reported in the nuclear matrix, and in the cytoplasm, apparently associated with the cytoskeleton. It is possible that CAD in the cytoplasm has a role unconnected with pyrimidine biosynthesis.

Cyclic Photophosphorylation in Vivo and its Relation to Photosynthetic CO(2)-Fixation

Salicylaldoxime (2 x 10(-3)m and less) inhibits cyclic photophosphorylation in intact Chlorella cells severely whereas photosynthetic O(2)-evolution and (14)CO(2)-fixation is hardly affected. Cyclic photophosphorylation in vivo was measured by following anaerobic light dependent glucose uptake. A similar difference in susceptibility has been observed with carbonylcyanide-p-trifluoromethoxyphenylhydrazone. Various controls exclude the possibility that the difference in inhibition was caused by differing experimental conditions or, in the case of glucose assimilation, by an inhibition of a reaction other than photophosphorylation.There also exists a great difference in light saturation of cyclic photophosphorylation and photosynthesis. Evidence is reported that at light saturation of glucose uptake light driven cyclic phosphorylation is indeed the limiting reaction.The results are considered as evidence that cyclic photophosphorylation does not contribute ATP stoichiometrically to photosynthetic CO(2)-fixation.