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K Hoff

Publications and source records attributed to K Hoff.

12 recordsLinked to original sources
PubMed2001

Jac1, a mitochondrial J-type chaperone, is involved in the biogenesis of Fe/S clusters in Saccharomyces cerevisiae.

A minor Hsp70 chaperone of the mitochondrial matrix of Saccharomyces cerevisiae, Ssq1, is involved in the formation or repair of Fe/S clusters and/or mitochondrial iron metabolism. Here, we report evidence that Jac1, a J-type chaperone of the mitochondrial matrix, is the partner of Ssq1 in this process. Reduced activity of Jac1 results in a decrease in activity of Fe/S containing mitochondrial proteins and an accumulation of iron in mitochondria. Fe/S enzyme activities remain low in both jac1 and ssq1 mutant mitochondria even if normal mitochondrial iron levels are maintained. Therefore, the low activities observed are not solely due to oxidative damage caused by excess iron. Rather, these molecular chaperones likely play a direct role in the normal assembly process of Fe/S clusters.

Aconitate Hydratase↗
PubMed1999

Saccharomyces cerevisiae ISU1 and ISU2: members of a well-conserved gene family for iron-sulfur cluster assembly.

Recent studies in bacteria and eukaryotes have led to the identification of several new genes implicated in the biogenesis of iron-sulfur (Fe/S) cluster-containing proteins. This report focuses on two genes of bakers yeast Saccharomyces cerevisiae, ISU1 and ISU2, which encode homologues to bacterial IscU and NifU, potential iron-binding or cluster-assembly proteins. As with other yeast genes implicated in Fe/S protein assembly, deletion of either ISU1 or ISU2 results in increased accumulation of iron within the mitochondria, loss of activity of the [4Fe-4S] aconitase enzyme, and suppression of oxidative damage in cells lacking cytosolic copper/zinc superoxide dismutase. Both genes are induced in strains expressing an activated allele of Aft1p, the iron-sensing transcription factor, suggesting that they are regulated by the iron status of the cell. Immunoblotting studies using an antibody directed against Escherichia coli IscU reveal that both Isu1p and Isu2p are localized primarily in the mitochondria and that Isu1p is the predominant form expressed under all growth conditions tested. The possible role of the Isu proteins in the assembly and/or repair of Fe/S clusters is discussed.

Amino Acid Sequence↗
PubMed1996

The effects of schema-based instruction on the mathematical word-problem-solving performance of students with learning disabilities.

This study examined the effects of a schema-based direct instruction strategy on the word-problem-solving performance of three third- and fourth-grade students (2 girls, 1 boy) with learning disabilities. An adapted multiple-probe-across-students design was used. Results indicated that the intervention was successful in increasing the percentage of correct solutions to word problems for all 3 students. In addition, maintenance of word-problem solving was seen 2 to 3 weeks after the study. Student interviews indicated that the strategy was beneficial. Further research with different students and problem types (e.g., multistep) and an investigation of the long-term effects of the strategy and its use in novel settings appear warranted.

Achievement↗
PubMed1993

The middle-Norway eye-screening study. III. The prevalence of capsular glaucoma is influenced by blood-group antigens.

The association between blood groups (ABO, Rh, Kell, Duffy) and pseudo-exfoliation syndrome, simple, and capsular glaucoma have been evaluated. The findings were: 1). No statistically significant abnormalities regarding blood group distribution in persons with pseudo-exfoliation syndrome. 2). In contrast to simple glaucoma, capsular glaucoma showed an abnormal distribution in the ABO- and the Kell-system. There was less glaucoma prevalence in the capsular A1-group compared to the O-group (p = 0.013), and less in the K1 negative group compared to the K1 positive one (p = 0.005). This trend was even escalated when combining the two systems: Among the K1 negative persons the glaucoma prevalence was lower in the A1-group compared to the O-group (p = 0.003). In the K1 negative group only 9 of 61 A1-persons developed glaucoma, in contrast to the K1 positive group where 4 of 4 A1-persons had glaucoma. This difference gave p < or = 0.00038, whereas the corresponding difference for the O-groups showed p = 0.65. It is concluded that once a person with blood group A1 has developed pseudo-exfoliation syndrome, the risk that capsular glaucoma will occur is about 7 times higher when that person is K1 positive compared to K1 negative. Perhaps this observation may be used as a prognostic factor for non-glaucomatous PE positive persons.

Aged↗
PubMed1991

The middle-Norway eye-screening study. II. Prevalence of simple and capsular glaucoma.

In this population-based screening study, dealing with 1941 persons above 64 years of age from three different municipalities, the overall open-angle glaucoma prevalence was found to be 8.3%. The prevalence in the separate areas (7.0%, 8.6%, and 9.5%) were not statistically different. Roughly 30% of the population with pseudo-exfoliation syndrome had glaucoma, and 4.2% had ocular hypertension, whereas the corresponding figures for those without pseudo-exfoliation were 4% and 0.8%, respectively. The high glaucoma rates are partly due to the high pseudo-exfoliation prevalence in the area. The prevalence of the capsular glaucoma increased towards a maximum between 75 and 79 years of age, whereafter the curve declined. This may indicate reduced survival time of glaucomatous patients.

Aged↗
PubMed1988

The Middle-Norway eye-screening study. I. Epidemiology of the pseudo-exfoliation syndrome.

This is the first population-based PE prevalence study allowing comparison of observations from different geographical areas. The prevalence of the PE syndrome for persons above 64 years of age was found to be 10.2, 21.0 and 19.6% in three municipalities lying distinctly apart. Of 343 married couples the man was PE-positive in 36, the woman in 34, and both in 12 cases. One of the 12 couples was excluded because the spouses were cousins. The observed number of 11 couples is significantly higher (P = 0.022) than expected assuming independent occurrence of PE syndrome. Two homozygote pairs of twins were found in this material, both of them discordant for the presence of PE syndrome. This fact along with the discrepancy between observed and expected numbers of PE positivity in both spouses may indicate environmental influence on the distribution of the syndrome.

Aged↗