Functional Neural Correlates of Semantic Fluency Task Performance in Mild Cognitive Impairment and Alzheimer's Disease: An FDG-PET Study

BACKGROUND

Total score (TS) of semantic verbal fluency test (SVFT) is generally used to interpret results, but it is ambiguous as to specific neural functions it reflects. Different SVFT strategy scores reflecting qualitative aspects are proposed to identify specific cognitive functions to overcome limitations of using the TS.

OBJECTIVE

Functional neural correlates of the TS as well as the other strategy scores in subjects with mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia using Fluorine-18-Fluorodeoxyglucose positron emission tomography (FDG-PET).

METHODS

Correlations between various SVFT scores (i.e., TS, mean cluster size, switching (SW), hard switching, cluster switching (CSW)) and cerebral glucose metabolism were explored using voxelwise whole-brain approach. Subgroup analyses were also performed based on the diagnosis and investigated the effects of disease severity on the associations.

RESULTS

Significant positive correlation between TS and cerebral glucose metabolism was found in prefrontal, parietal, cingulate, temporal cortex, and subcortical regions. Significantly increased glucose metabolism associated with the SW were found in similar but smaller regions, mainly in the fronto-parieto-temporal regions. CSW was only correlated with the caudate. In the subgroup analysis conducted to assess different contribution of clinical severity, differential associations between the strategy scores and regional glucose metabolism were found.

CONCLUSION

SW and CSW may reflect specific language and executive functions better than the TS. The SVFT is influenced by brain dysfunction due to the progression of AD, as demonstrated by the SW with larger involvement of temporal lobe for the AD, and CSW with significant association only for the MCI.

Normative Study of the Block Design Test for Adults Aged 55 Years and Older in Korean Aging Population

OBJECTIVE

The Block Design Test (BDT) is known to be an effective measure in diagnosing age-related cognitive decline of visuospatial function. The goal of this study is to investigate the effects of age, education years, and gender on the performance of the BDT and to provide normative data in Korean community-dwelling participants who are 55 to 90 years old.

METHODS

The participants were 432 non-demented adults aging from 55 to 90 years old. The BDT was administered to participants according to its manual. Multiple linear regressions and analyses of variance were conducted, including age, gender, and educations were used as covariates.

RESULTS

Age, educational years, and gender were found to be significantly associated with performance on the BDT. As age increased, BDT performance decreased. Educational years were associated with BDT performance. Men showed higher performance (29.9±10.3) compare to women (26.1±8.7). The BDT is influenced by age, educational years, and gender.

CONCLUSION

Unlike the previous study, the current study shows that gender has a significant influence in visuospatial ability in the old population. Present normative data will be useful for clinicians in evaluating aging participants with cognitive impairment.

Association of Retinal Changes With Alzheimer Disease Neuroimaging Biomarkers in Cognitively Normal Individuals

Importance

Retinal biomarkers reflecting in vivo brain Alzheimer disease (AD) pathologic abnormalities could be a useful tool for screening cognitively normal (CN) individuals at the preclinical stage of AD.

Objectives

To investigate the association of both functional and structural alterations of the retina with in vivo AD pathologic abnormalities in CN older adults and model a screening tool for detection of preclinical AD.

Design, Setting, and Participants

This cross-sectional study included a total of 49 CN individuals, and all assessment was done at the Seoul National University Hospital, Seoul, South Korea. All participants underwent complete ophthalmic examination, including swept-source optical coherence tomography (SS-OCT) and multifocal electroretinogram as well as amyloid-β (Aβ) positron emission tomography and magnetic resonance imaging. Data were collected from January 1, 2016, through October 31, 2017, and analyzed from February 1, 2018, through June 30, 2020.

Main Outcomes and Measures

For structural parameters of the retina, the thickness of the macula and layer-specific thicknesses, including peripapillary retinal nerve fiber layer and ganglion cell-inner plexiform layer measured by SS-OCT, were used for analysis. For functional parameters of the retina, implicit time and amplitude of rings 1 to 6 measured by multifocal electroretinogram were used.

Results

Of the 49 participants, 25 were women (51.0%); mean (SD) age was 70.6 (9.4) years. Compared with 33 CN individuals without Aβ deposition (Aβ-CN), the 16 participants with Aβ (Aβ+CN) showed reduced inner nasal macular thickness (mean [SD], 308.9 [18.4] vs 286.1 [22.5] μm; P = .007) and retinal nerve fiber layer thickness, particularly in the inferior quadrant (133.8 [17.9] vs 103.8 [43.5] μm; P = .003). In addition, the Aβ+CN group showed prolonged implicit time compared with the Aβ-CN group, particularly in ring 5 (41.3 [4.0] vs 38.2 [1.3] milliseconds; P = .002). AD-related neurodegeneration was correlated with the thickness of the ganglion cell-inner plexiform layer only (r = 0.41, P = .005). The model to differentiate the Aβ+CN vs Aβ-CN groups derived from the results showed 90% accuracy.

Conclusions and Relevance

The findings of this study showing both functional as well as structural changes of retina measured by multifocal electroretinogram and SS-OCT in preclinical AD suggest the potential use of retinal biomarkers as a tool for early detection of in vivo AD pathologic abnormalities in CN older adults.

Functional Neural Correlates of the WAIS-IV Block Design Test in Older Adult with Mild Cognitive Impairment and Alzheimer's Disease

The Wechsler Adult intelligence scale-Revised (WAIS-R) Block design test (BDT) is a neuropsychological test widely used to assess cognitive declines in aging population. Previous studies suggest parietal lobe is the key region to influence the performance on the BDT; yet, it has not been clearly identified. The aim of the current study, therefore, is to identify the functional neural correlates of the BDT in older adults with mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia patients. The current study includes 213 cognitively impaired mid to old-aged community dwelling Korean. All participants underwent comprehensive clinical and neuropsychological assessments and 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) scans. Performance on the BDT was assessed using the WAIS-IV Korean version. Voxel-wise analyses were used to investigate the correlation between regional cerebral glucose metabolism and BDT performance. The same analyses were conducted on the subgroups categorized by clinical severity based on the Clinical Dementia Rating (CDR). Significant positive correlations between performance on the BDT and regional cerebral glucose metabolism were found bilaterally in the inferior parietal lobules, right thalamus and right middle frontal gyrus. Our results suggest that performance on the BDT in MCI and AD patients functionally relies on the brain regions known to be associated with motor and executive functions in addition to visuospatial function.

Validation of the Korean Version of the Anosognosia Questionnaire for Dementia

OBJECTIVE

Anosognosia is a common phenomenon in individuals with dementia. Anosognosia Questionnaire for dementia (AQ-D) is a well-known scale for evaluating anosognosia. This study aimed to establish a Korean version of the AQ-D (AQ-D-K) and to evaluate the reliability and validity of the AQ-D-K in patients with Alzheimer's disease (AD) dementia.

METHODS

We translated the original English version of AQ-D into Korean (AQ-D-K). Eighty-four subjects with very mild or mild AD dementia and their caregivers participated. Reliability of AQ-D-K was assessed by internal consistency and one-month test-retest reliability. Construct validity and concurrent validity were also evaluated.

RESULTS

Internal consistencies of the AQ-D-K patient form and caregiver form were high (Cronbach alpha 0.95 and 0.93, respectively). The test-retest reliability of AQ-D-K measured by intra-class correlation coefficient was 0.84. Three factors were identified: 1) anosognosia of instrumental activity of daily living; 2) anosognosia basic activity of daily living; and 3) anosognosia of depression and disinhibition. AQ-D-K score was significantly correlated with the clinician-rated anosognosia rating scale (ARS), center for epidemiological studies-depression scale (CES-D) and state-trait anxiety inventory (STAI).

CONCLUSION

The findings suggest that the AQ-D-K is a reliable and valid scale for evaluating anosognosia for AD dementia patients using Korean language.

Blood Hemoglobin, in-vivo Alzheimer Pathologies, and Cognitive Impairment: A Cross-Sectional Study

Background: Despite known associations between low blood hemoglobin level and Alzheimer's disease (AD) or cognitive impairment, the underlying neuropathological links are poorly understood. We aimed to examine the relationships of blood hemoglobin levels with in vivo AD pathologies (i.e., cerebral beta-amyloid [Aβ] deposition, tau deposition, and AD-signature degeneration) and white matter hyperintensities (WMHs), which are a measure of cerebrovascular injury. We also investigated the association between hemoglobin level and cognitive performance, and then assessed whether such an association is mediated by brain pathologies.

Methods: A total of 428 non-demented older adults underwent comprehensive clinical assessments, hemoglobin level measurement, and multimodal brain imaging, including Pittsburgh compound B-positron emission tomography (PET), AV-1451 PET, fluorodeoxyglucose (FDG)-PET, and magnetic resonance imaging. Episodic memory score and global cognition scores were also measured.

Results: A lower hemoglobin level was significantly associated with reduced AD-signature cerebral glucose metabolism (AD-CM), but not Aβ deposition, tau deposition, or WMH volume. A lower hemoglobin level was also significantly associated with poorer episodic memory and global cognition scores, but such associations disappeared when AD-CM was controlled as a covariate, indicating that AD-CM has a moderating effect.

Conclusion: The present findings suggest that low blood hemoglobin in older adults is associated with cognitive decline via reduced brain metabolism, which seems to be independent of those aspects of AD-specific protein pathologies and cerebrovascular injury that are reflected in PET and MRI measures.

Long-Term Exposure to PM10 and in vivo Alzheimer’s Disease Pathologies

Background: Previous studies indicated an association between Alzheimer’s disease (AD) dementia and air particulate matter (PM) with aerodynamic diameter <10μm (PM10), as well as smaller PM. Limited information, however, is available for the neuropathological links underlying such association. Objective: This study aimed to investigate the relationship between long-term PM10 exposure and in vivo pathologies of AD using multimodal neuroimaging. Methods: The study population consisted of 309 older adults without dementia (191 cognitively normal and 118 mild cognitive impairment individuals), who lived in Republic of Korea. Participants underwent comprehensive clinical assessments, 11C-Pittsburg compound B (PiB) positron emission tomography (PET), and magnetic resonance imaging scans. A subset of 78 participants also underwent 18F-AV-1451 tau PET evaluation. The mean concentration of PM with aerodynamic diameter <10μm over the past 5 years (PM10mean) collected from air pollution surveillance stations were matched to each participant’s residence. Results: In this non-demented study population, of which 62% were cognitively normal and 38% were in mild cognitive impairment state, exposure to the highest tertile of PM10mean was associated with increased risk of amyloid-β (Aβ) positivity (odds ratio 2.19, 95% confidence interval 1.13 to 4.26) even after controlling all potential confounders. In contrast, there was no significant associations between PM10mean exposure and tau accumulation. AD signature cortical thickness and white matter hyperintensity volume were also not associated with PM10mean exposure. Conclusion: The findings suggest that long-term exposure to PM10 may contribute to pathological Aβ deposition.

Multiparity, Brain Atrophy, and Cognitive Decline

Background

Multiparity – grand multiparity (i.e., five or more childbirths) in particular – has been reported to have an association with increased risk of Alzheimer’s disease (AD) dementia or related cognitive decline in women. However, the pathological links underlying this relationship are still unknown. This study was conducted to examine the relationships of multiparity with cerebral amyloid-beta (Aβ) deposition, brain atrophy, and white matter hyperintensities (WMHs).

Methods

In this study, total of 237 older women with 148 cognitively normal and 89 mild cognitive impairment from the Korean Brain Aging Study for Early Diagnosis and Prediction of Alzheimer’s Disease (KBASE) were included. Participants underwent clinical and neuropsychological assessments in addition to ¹¹C-labeled Pittsburgh Compound B positron emission tomography, and magnetic resonance imaging. The associations of parity with Aβ deposition, hippocampal volume, cortical volume, WMH volume and mini-mental status examination (MMSE) score were examined.

Results

Participants with grand multiparity showed significantly reduced adjusted hippocampal volume, spatial pattern of atrophy for recognition of AD volume and spatial pattern of atrophy for recognition of brain aging volume even after controlling for potential confounders. Furthermore, MMSE score was also significantly lower in this group. In contrast, grand multiparity did not show any association with global Aβ retention, Aβ positivity rate, or WMH volume, regardless of covariates.

Conclusion

Our findings suggest that grand multiparity contributes to cognitive decline or increased dementia risk in older women by aggravating amyloid-independent hippocampal or cortical atrophy.

Resting State Glucose Utilization and Adult Reading Test Performance

Adult reading tests (ART) have been widely used in both research and clinical settings as a measure of premorbid cognitive abilities or cognitive reserve. However, the neural substrates underlying ART performance are largely unknown. Furthermore, it has not yet been examined whether the neural substrates of ART performance reflect the cortical regions associated with premorbid intelligence or cognitive reserve. The aim of the study is to identify the functional neural correlates of ART performance using 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging in the cognitively normal (CN) middle- and old-aged adults. Voxel-wise analyses revealed positive correlations between glucose metabolism and ART performance in the frontal and primary somatosensory regions, more specifically the lateral frontal cortex, anterior cingulate cortex and postcentral gyrus (PCG). When conducted again only for amyloid-β (Aβ)-negative individuals, the voxel-wise analysis showed significant correlations in broader areas of the frontal and primary somatosensory regions. This is the first neuroimaging study to directly demonstrate the cerebral resting-state glucose utilization associated with ART performance. Our findings provide important evidence at the neural level that ART predicts premorbid general intelligence and cognitive reserve, as brain areas that showed significant correlations with ART performance correspond to regions that have been associated with general intelligence and cognitive reserve.

Normative Data for the Logical Memory Subtest of the Wechsler Memory Scale-IV in Middle-Aged and Elderly Korean People

OBJECTIVE

The purpose of this study is to identify the demographic variables that are affecting performances on the Logical Memory (LM) subtest included in the Korean version of the Wechsler Memory Scale (WMS)-IV and to provide normative data on the LM subtest for the middle-age and elderly Korean people.

METHODS

The participants were 435 non-demented adults aging from 50 to 90 and with the educational level ranging from 0 to 21 years.

RESULTS

Age and education were found to be significantly associated with performance on the LM subtest, while gender effect was not statistically significant. Therefore, we stratified the norm blocks by age and education. Age was divided into three groups: 50-59, 60-74, and 75-90 years. Education was stratified into three groups: 0-8 years, 9-12 years, and 13 years or more.

CONCLUSION

The normative data provided in the current study are expected to be useful in clinical and research settings to detect or define subtle changes in episodic memory in Korean adults and elderly, and can also be used for cross-cultural comparison of verbal episodic memory performance among elderly populations using different languages.

Low-carbohydrate diet and the risk of metabolic syndrome in Korean adults

BACKGROUND & AIMS

The association of low-carbohydrate diet with weight loss and the risk of cardiovascular diseases has recently been the focus of increasing research attention. However, studies on low-carbohydrate diet in the Asian population are limited. The present study was aimed to examine the association between low-carbohydrate diet and metabolic syndrome among Korean adults.

METHODS AND RESULTS

A total of 16,349 participants aged 30 years or older who participated in a 24-h dietary recall survey of the fifth and sixth Korea National Health and Nutrition Examination Survey were included in this study. Low-carbohydrate diet was evaluated using the low-carbohydrate-diet score, which was calculated based on the percentage of energy from carbohydrate, protein, and fat by sex. The association between the low-carbohydrate-diet score and metabolic syndrome was analyzed using multiple logistic regression analysis. A low-carbohydrate diet was not associated with metabolic syndrome and its components such as waist circumference, blood pressure, and triglyceride levels. However, women in the highest decile of the animal- or plant-based low-carbohydrate-diet score showed a decreased risk of reduced high-density lipoprotein (HDL)-cholesterol levels, and men in the highest decile of the animal-based low-carbohydrate-diet score showed a decreased risk of reduced HDL-cholesterol levels than those in the lowest decile of the low-carbohydrate-diet score.

CONCLUSION

These findings indicate that, in Korea, a low-carbohydrate diet did not increase the risk of metabolic syndrome among adults who typically consume a high-carbohydrate low-fat diet. However, it may moderately decrease the risk of reduced HDL-cholesterol levels.

A fruit, milk and whole grain dietary pattern is positively associated with bone mineral density in Korean healthy adults

BACKGROUND/OBJECTIVES

Osteoporosis is a major health problem that will grow in burden with ageing of the global population. Modifiable risk factors for osteoporosis, including diet, have significant implications for disease prevention. We examined associations between dietary patterns and bone mineral density (BMD) in a Korean adult population.

SUBJECTS/METHODS

In total, 1828 individuals from the Healthy Twin Cohort were included as subjects. Information on general characteristics, lifestyles and health status was obtained through a health examination, and BMD was assessed using DEXA. Dietary intake was assessed using a 3-day food record, and dietary patterns were examined by factor analysis. Associations between dietary patterns and BMD were examined using mixed linear regression, adjusting for family and twin structure as well as other potential risk factors for bone health.

RESULTS

Four dietary patterns were identified (Rice and kimchi; eggs, meat and flour; Fruit, milk and whole grains; and Fast food and soda). The 'Fruit, milk and whole grains' pattern was associated with a reduced risk of having low BMD in men (odds ratio (OR)=0.38; 95% confidence interval (CI)=0.22-0.67) and women (OR=0.45; 95% CI=0.28-0.72) and was positively associated with BMD at multiple sites. The 'rice and kimchi' pattern had a positive association with only whole-arm BMD in men and women.

CONCLUSIONS

Our results suggest that a dietary pattern with high intake of dairy products, fruits and whole grains may contribute positively to bone health in a Korean adult population, and dietary pattern-based strategies could have potential in promoting bone health.

A traditional Korean dietary pattern and metabolic syndrome abnormalities

BACKGROUND AND AIMS

Using national data, we explored the relationship between dietary patterns and metabolic abnormalities to address how the traditional Korean diet, high in carbohydrate and low in animal fat with plenty of plant foods, has influenced metabolic abnormalities in the adult population.

METHODS AND RESULTS

We examined cross-sectional associations between dietary patterns and the risk of metabolic abnormalities in 4,730 subjects aged 20 years or more using both health and dietary data from the 2005 Korean National Health and Nutrition Examination survey. Three evident dietary patterns were derived by cluster analysis: 'Traditional' (50.3% of total population), 'Meat and Alcohol, (15.8%) and 'Korean Healthy' (33.9%). The 'Traditional' group was characterised by high consumptions of rice and kimchi, while the 'Korean healthy' group ate a modified Korean-style diet with various foods such as noodles, bread, eggs and milk, and the 'Meat and Alcohol' group had high consumptions of processed meat and alcohol. Compared with the 'Traditional' pattern, the 'Meat and Alcohol' pattern was associated with a 33% increased risk of having elevated blood glucose, a 21% increased risk of having elevated serum triglycerides and a 21% increased risk of having elevated blood pressure. However, the 'Traditional' pattern showed a 23% increased risk of having low high density lipoprotein (HDL)-cholesterol compared with the other two patterns by logistics analysis.

CONCLUSIONS

Fifty percent of the Korean adult population continues to follow a traditional dietary pattern, having beneficial effects with respect to some metabolic abnormalities. However, the high prevalence of low HDL-cholesterol, attributable to a high-carbohydrate diet, should be considered.

Expression analysis of human β-secretase in transgenic tomato fruits

An emerging strategy in biomanufacturing involves using transgenic plants to express recombinant pharmaceutical and industrial proteins in large quantities. β-Site APP cleaving enzyme 1 (β-secretase 1, BACE1) is an enzyme involved in the abnormal production of Aβ42, the major component of senile plaques in Alzheimer's disease (AD). Thus, BACE1 represents a key target protein in the development of new potential drugs to treat Alzheimer's disease. We aimed to develop a tomato-derived recombinant BACE1 (rBACE1) protein to serve as a vaccine antigen that would promote an immune response. We utilized a plant expression cassette, pE8BACE, to optimize BACE1 expression in tomato fruits. Polyemerase chain reaction and Southern blot analyses verified integration of the BACE1 gene into the plant genome. Northern and Western blot analyses demonstrated successful mRNA and protein expression of rBACE1, respectively; the Sensizyme assay kit estimated the expression level of rBACE1 protein at 136 ± 7 ng mg⁻¹ total soluble protein. The tomato-derived rBACE1 retains its activity for a long storage period at cool or room temperature, and is highly resistant to degradation in conditions such as low acidity. Tomato-derived rBACE1 was severely degraded by heat or boiling. The proteolytic activity of tomato-derived rBACE1, confirmed by fluorescence resonance transfer assay, was similar to that of a commercial sample of Escherichia coli-derived BACE1.

Ret finger protein inhibits muscle differentiation by modulating serum response factor and enhancer of polycomb1

Skeletal myogenesis is precisely regulated by multiple transcription factors. Previously, we demonstrated that enhancer of polycomb 1 (Epc1) induces skeletal muscle differentiation by potentiating serum response factor (SRF)-dependent muscle gene activation. Here, we report that an interacting partner of Epc1, ret finger protein (RFP), blocks skeletal muscle differentiation. Our findings show that RFP was highly expressed in skeletal muscles and was downregulated during myoblast differentiation. Forced expression of RFP delayed myoblast differentiation, whereas knockdown enhanced it. Epc1-induced enhancements of SRF-dependent multinucleation, transactivation of the skeletal α-actin promoter, binding of SRF to the serum response element, and muscle-specific gene induction were blocked by RFP. RFP interfered with the physical interaction between Epc1 and SRF. Muscles from rfp knockout mice (Rfp(-/-)) mice were bigger than those from wild-type mice, and the expression of SRF-dependent muscle-specific genes was upregulated. Myotube formation and myoblast differentiation were enhanced in Rfp(-/-) mice. Taken together, our findings highlight RFP as a novel regulator of muscle differentiation that acts by modulating the expression of SRF-dependent skeletal muscle-specific genes.

Expression of the hepatitis B surface S and preS2 antigens in tubers of Solanum tuberosum

In an attempt to develop an edible vaccine, we transformed a recombinant hepatitis B virus (HBV) gene encoding the middle protein of HBV that contains the surface S and preS2 antigen into potato by Agrobacterium-mediated transformation. The HBV gene was under control of either the CaMV 35S promoter, the double 35S promoter with the AlMV 5' non-translated leader sequence, or the tuber-specific patatin promoter. HBV mRNA levels were higher with the 35S promoter than with the double 35S and patatin promoters; however, the levels of the S and preS2 antigen in the transformed tubers were higher with the patatin promoter than with the CaMV 35S and double promoters. The levels of preS2 antigen produced are the highest reported to date. Transgenic potato tubers were fed to mice, and the mice showed an immune response against the HBV S antigen.

Serum extracellular superoxide dismutase activity as an indicator of zinc status in humans

The present study focused on whether serum extracellular superoxide dimutase (EC-SOD) activity can be used as a functional indicator of marginal zinc deficiency in humans. Subjects in this study were 444 healthy adults over 30 yr of age living a normal rural life in Kyunggi province, Korea. The mean dietary zinc intake of subjects obtained from one 24-h recall was 6.41 +/- 4.35 mg and the average serum zinc concentration of the subjects was 11.06 +/- 2.44 micromol/L. Subjects were divided into three groups by serum zinc concentrations: adequate (serum zinc >10.7 micromol/L), low (serum zinc 9.0-10.7 micromol/L), and very low (serum zinc <9.0 micromol/L) groups. A total of 50 subjects were selected from the three groups for analysis of EC-SOD activities. The EC-SOD activity of subjects increased with increasing serum zinc concentrations, and the activities of the three groups were significantly different as indicated by the Kruskal-Wallis test (p = 0.0239). Also, serum EC-SOD activities were significantly correlated with serum zinc concentrations (r = 0.289, p = 0.04). Serum EC-SOD activities, however, were not significantly correlated to the dietary zinc intakes. In conclusion, these results show that EC-SOD activities are decreased in subjects with low serum zinc concentrations and suggest that EC-SOD activity may be a functional indicator of zinc nutritional status in humans.

BAL fluid contains detectable superoxide dismutase 1 activity

OBJECTIVE

This study determined which, if any, of the three superoxide dismutase (SOD) enzyme activities were detectable in BAL fluid (BALF).

BACKGROUND

The identity and concentrations of antioxidant molecules in BALF have not been fully characterized. One important class of antioxidants is that of the SOD enzymes.

METHODS

BALF from control nonsmokers (n=9), smokers (n=7), and asthmatic subjects (n=12) were examined for SOD activity by a modified pyrogallol auto-oxidation method. The particular SOD enzyme or enzymes responsible for any activity were identified based on activity inhibition data and gel filtration column chromatography patterns.

RESULTS

SOD activity was detected in all samples. Unlike serum or some other fluids, in which the enzyme extracellular SOD accounts for virtually all SOD activity, the enzyme SOD 1 accounted for virtually all SOD activity. BALF SOD activities were lower for smokers than for control or asthmatic subjects (p<0.05).

CONCLUSION

BALF SOD 1 activities can be measured as part of lung antioxidant studies. Data from a limited number of subjects suggested that smokers can have low BALF SOD values.

Cloning and characterization of one member of the chalcone synthase gene family from Solanum tuberosum L

We have isolated a chalcone synthase gene 2 (ST-CHS2) from potato by rapid amplification of cDNA ends by PCR. CHS2 cDNA had high homology to tomato LET-CHS2 (98%), petunia PHCHSJ (94%), potato ST-CHS1B (92%), petunia PHCHSA (92%), and LET-CHS1 (90%) at the overall 389-amino acid level. Genomic hybridization analysis indicated that CHS genes of potato comprise a family of at least six individual members.

Marginal zinc deficiency in older adults: responsiveness of zinc status indicators

OBJECTIVE

Suspicions that mild zinc deficiency is common among the elderly cannot be confirmed or refuted because definitive indicators of zinc status are lacking. The goal of this study was to document the clinical responsiveness of parameters of zinc status in a group of older adults consuming a carefully controlled diet: first moderately low in zinc (3.97 mg/day for 15 days) and then high in zinc (28.19 mg/day for 6 days).

METHODS

Fifteen older adults (mean age = 66.6 yrs) volunteered to consume a marginally zinc-deficient diet for 15 days followed by 6 days of zinc repletion. Plasma concentrations of erythrocyte metallothionein and the enzyme 5'-nucleotidase, as well as levels of zinc, alkaline phosphatase, copper and ceruloplasmin were measured before and after zinc depletion and repletion.

RESULTS

Plasma zinc levels were not altered during the study. Alkaline phosphatase (AP) values did not change in the expected direction, although a small decrease in AP following zinc repletion was statistically significant. Erythrocyte metallothionein results followed a pattern similar to that of alkaline phosphatase, little change, but a small, statistically significant drop after zinc repletion. As expected, there were no diet-associated changes in plasma copper and ceruloplasmin levels. In contrast, plasma concentrations of the enzyme 5'-nucleotidase decreased (p < 0.01) from 2.7 +/- 0.5 to 1.1 +/- 0.5 U during zinc depletion and increased (p < 0.05) to 2.2 +/- 0.4 U after 6 days of repletion.

CONCLUSIONS

Mild zinc deficiency is difficult to detect. In this study, traditional indicators such as plasma zinc and alkaline phosphatase did not change as would be expected in response to alterations in zinc intake. Likewise, erythrocyte metallothionein did not respond to altered zinc intakes as expected but this factor may reflect long-standing or more severe zinc depletion and thus requires additional study. Activity of the enzyme 5'-nucleotidase appears responsive to acute changes in zinc intake; however, more work is needed to define how well these activities will reflect zinc intake in other types of subjects.