Manuela Dittmar

A novel mutation in the DNASE1 gene is related with protein instability and decreased enzyme activity in thyroid autoimmunity.

A deficiency in the DNase enzyme, and thereby, a failure to remove DNA from nuclear antigens promotes disease susceptibility to autoimmune disorders. This study examined in patients with autoimmune thyroid disease (AITD) whether a reduced DNase activity is associated with sequence variations in the DNASE1 gene. The study included 18 patients with AITD, their 10 relatives, and 111 unrelated healthy controls. Serum DNase activity was determined with a validated, standardized enzyme-linked-immunosorbent assay. The promoter and all nine exons of the DNASE1 gene were sequenced. Heat stability of DNase enzyme was tested. In patients with AITD, a novel mutation (1218G>A, exon 5) and multiple polymorphisms were identified in the DNASE1 gene. The allele frequency of the mutation was increased in patients vs controls (P=0.001). In contrast to controls, the novel mutation was present in all five members of a family with AITD showing decreased DNase activity. The mutation resulted in the replacement of highly conserved valine with methionine at amino acid position 89 of the DNase enzyme. It was related to lowered heat stability and lowered activity of the enzyme. The identified new mutation and numerous polymorphisms, noted for the first time in AITD patients, may alter transcription and translation of the DNASE1 gene, thereby decreasing the stability and activity of the corresponding enzyme.

Accuracy of a Portable Multisensor Body Monitor for Predicting Resting Energy Expenditure in Older People: A Comparison with Indirect Calorimetry

Background: Accurate and comfortable methods are needed to determine resting energy expenditure (REE) in older people who are characterized by a lowered metabolic rate. The portable SenseWear® armband (SWA) body monitor, worn on the right upper arm, can easily be used by this age group in an ambulatory manner. Objective: The purpose of this study was to evaluate the reliability and accuracy of the SWA armband in determining REE in healthy, normal-weight older people. Methods: Participants were 49 older, community-dwelling volunteers aged 60–87 years. Reliability was tested in all subjects. Accuracy was analyzed in 32 subjects by comparing REE estimated by SWA against REE measured by indirect calorimetry as a criterion method. Data were simultaneously and continuously recorded for 20 min in the morning. In the same subjects, REE determined by SWA from night recording was evaluated for accuracy against indirect calorimetry. The agreement between methods was assessed by the Bland-Altman procedure. Results: (1) REE measured by SWA was reliable when comparing 2 consecutive measurements (typical error: 1.9%). (2) REE calculated from morning recording (1,543 ± 181 kcal/24 h) was higher than REE from night recording (1,564 ± 192 kcal/24 h; p = 0.018). (3) Compared with REE by indirect calorimetry (1,377 ± 228 kcal/24 h) for accuracy, the SWA overestimated mean REE in the older people by 12 and 14%, respectively, for morning and night recording (each p < 0.001). Conclusions: The SWA provides a reliable estimate of REE in healthy older subjects and has the advantage of easy handling. The 20-min recording time, which was recommended by the manufacturer, can be applied. However, the SWA overestimates REE in this group, possibly due to age-related changes in skin conductance and thermoregulation, both being measured by sensors of the SWA armband. This requires improving the SWA by developing better fitting algorithms for predicting REE in older people.

Organic Elemental Composition in Fingernail Plates Varies between Sexes and Changes with Increasing Age in Healthy Humans

Background: Keratin, an α-helical fibrous protein, is the primary component of human nail plates. No data on age-related changes in healthy subjects are present. Objective: This study investigated whether keratin amount and composition, as indicated by organic elemental composition of fingernails, varies with aging and between sexes. Methods: Nail clippings from 225 healthy individuals (93 males, 132 females), aged 20–90 years, were analyzed for carbon (C), nitrogen (N), and sulfur (S) contents with an automatic elemental analyzer. C/N and N/S ratios were calculated. The C/N ratio is indicative of keratin composition, i.e. the ratio of α-amino acids and protein. The relationship of elemental composition with dietary intake was analyzed by standardized food record. Results: Females have in their nails more sulfur (p < 0.001) and less nitrogen (p = 0.001), and thereby, a lower N/S ratio than males, whereas their carbon content is not different. With aging, the carbon content increases (p < 0.01, both sexes) and the nitrogen content decreases (p = 0.05, females), both leading to an increased C/N ratio (p < 0.001). By contrast, the sulfur content and the N/S ratio do not change with aging (p > 0.05). The carbon content correlates positively with macronutrient intake in females. Nitrogen and sulfur contents are not related with dietary intake. Conclusions: Results suggest that the N/S ratio is indicative of sex differences and the C/N ratio of aging in healthy humans. The increasing carbon content with ongoing age could be explained by loss of inorganic material from the nails, followed by a subsequent increase of organic material. The increasing C/N ratio gives evidence that keratin composition changes towards a higher amount of α-amino acids with aging.

Older poor-sleeping women display a smaller evening increase in melatonin secretion and lower values of melatonin and core body temperature than good sleepers.

Melatonin concentration and core body temperature (CBT) follow endogenous circadian biological rhythms. In the evening, melatonin level increases and CBT decreases. These changes are involved in the regulation of the sleep-wake cycle. Therefore, the authors hypothesized that age-related changes in these rhythms affect sleep quality in older people. In a cross-sectional study design, 11 older poor-sleeping women (aged 62–72 yrs) and 9 older good-sleeping women (60–82 yrs) were compared with 10 younger good-sleeping women (23–28 yrs). The older groups were matched by age and body mass index. Sleep quality was assessed by the Pittsburgh Sleep Quality Index questionnaire. As an indicator of CBT, oral temperature was measured at 1-h intervals from 17:00 to 24:00 h. At the same time points, saliva samples were collected for determining melatonin levels by enzyme-linked immunosorbent assay (ELISA). The dim light melatonin onset (DLMO), characterizing the onset of melatonin production, was calculated. Evening changes in melatonin and CBT levels were tested by the Friedman test. Group comparisons were performed with independent samples tests. Predictors of sleep-onset latency (SOL) were assessed by regression analysis. Results show that the mean CBT decreased in the evening from 17:00 to 24:00 h in both young women (from 36.57°C to 36.25°C, p < .001) and older women (from 36.58°C to 35.88°C, p < .001), being lowest in the older poor sleepers (p < .05). During the same time period, mean melatonin levels increased in young women (from 16.2 to 54.1 pg/mL, p < .001) and older women (from 10.0 to 23.5 pg/mL, p < .001), being lowest among the older poor sleepers (from 20:00 to 24:00 h, p < .05 vs. young women). Older poor sleepers also showed a smaller increase in melatonin level from 17:00 to 24:00 h than older good sleepers (mean ± SD: 7.0 ± 9.63 pg/mL vs. 15.6 ± 24.1 pg/mL, p = .013). Accordingly, the DLMO occurred at similar times in young (20:10 h) and older (19:57 h) good-sleeping women, but was delayed ∼50 min in older poor-sleeping women (20:47 h). Older poor sleepers showed a shorter phase angle between DLMO and sleep onset, but a longer phase angle between CBT peak and sleep onset than young good sleepers, whereas older good sleepers had intermediate phase angles (insignificant). Regression analysis showed that the DLMO was a significant predictor of SOL in the older women (R2 = 0.64, p < .001), but not in the younger women. This indicates that melatonin production started later in those older women who needed more time to fall asleep. In conclusion, changes in melatonin level and CBT were intact in older poor sleepers in that evening melatonin increased and CBT decreased. However, poor sleepers showed a weaker evening increase in melatonin level, and their DLMO was delayed compared with good sleepers, suggesting that it is not primarily the absolute level of endogenous melatonin, but rather the timing of the circadian rhythm in evening melatonin secretion that might be related to disturbances in the sleep-wake cycle in older people. (Author correspondence: mdittmar@zoologie.uni-kiel.de)

Prevalence of Sarcopenia among Older Community-Dwelling People with Normal Health and Nutritional State

This study analyzed whether sarcopenia, a risk factor for disability in the aged, also occurs in healthy community-dwelling elders with normal nutritional state. As indicators, body cell mass (BCM) and lean body mass (LBM) were determined in 110 Germans (ages 60–83) using bioimpedance analysis. Nutritional status, muscle function, anthropometry, and physical activity level were investigated. Sarcopenia was already present in well nourished healthy elders. Its prevalence depended on the measure of muscle mass used (BCM percent, 22 percent males, 20 percent females; LBM percent, 4 percent males, 11 percent females). In conclusion, screening for presence of sarcopenia is needed in healthy, well-nourished elderly populations requiring an international standardization.

Exposure to toxic agents alters organic elemental composition in human fingernails

BACKGROUND AND OBJECTIVE The human fingernail plate is highly keratinized. The keratin structure is held together by disulfide bonds. The organic elements sulfur and nitrogen occur almost exclusively in amino acids of the nail plate. This study analyzed whether occupational exposure to harmful chemical agents alters the organic elemental composition in fingernails. SUBJECTS AND METHODS Participants were 71 occupationally exposed workers (49 hairdressers, 22 painters) and 49 unexposed controls. Aspects of exposure were assessed by questionnaire. Nail clippings of index and little fingers were analyzed for sulfur (S), nitrogen (N), carbon (C), and hydrogen (H) contents, using an automatic elemental analyzer (Vario EL III, Elementar Analysensysteme, Hanau, Germany). C/N, N/S, and C/S ratios were calculated. Reliability of elemental measurements was tested in a subset. RESULTS Reliability analysis of elemental measurements showed a very good agreement. Both painters and hairdressers displayed in their fingernails significantly lower percentages of sulfur, but higher percentages of carbon than unexposed controls. A trend was observed in that sulfur content was lowest in those hairdressers who reported structural changes in their fingernails. As a consequence, the C/S and N/S ratios were significantly increased in both exposed groups. CONCLUSION The occupational use of harmful substances leads to decreased sulfur levels in the exposed persons, probably due to diminution of sulfur-rich proteins in the nails, resulting from destruction of disulfide-bonds by alkaline and acid groups. Thus, the C/S ratio seems to be a useful indicator for the amount of damage of nail protein by harmful agents.

The Proinflammatory Cytokine TNF-α -308 AA Genotype is Associated with Polyglandular Autoimmunity

Data regarding polymorphisms of immunoregulatory genes in polyglandular autoimmunity (PGA) are lacking. We have analyzed whether the polymorphism of the proinflammatory cytokine gene TNF-α; -308 and mutations of the autoimmune regulator (AIRE) gene were associated with PGA in adults. Sixty-seven patients with PGA and 209 healthy controls were genotyped by multiplex minisequencing with capillary electrophoresis on an ABI PRISM-310 genetic analyzer. HLA DRB1 typing was performed using polymerase-chain-reaction-amplified DNA hybridized with sequence-specific-oligonucleotide probes (PCR-SSO). The TNF-α; -308*A allele occurred more frequently in patients (0.269) than in controls (0.163, P = 0.008, Pc = 0.016). Also, TNF-α; -308*A carriers were more frequent in patients than controls (47.8% vs. 31.1%, OR = 1.89, 95%CI = 1.19−3.00). The frequency of the AA genotype was increased in PGA (P = 0.014, Pc = 0.042). PGA patients with autoimmune thyroid disease and the TNF-α; -308 AA genotype showed the highest prevalence of thyroid autoantibodies (TPO, P = 0.04; Tg, P = 0.003). HLA-DRB1*03 and TNF-α; -308*A alleles were strongly associated in patients with PGA (87.5%, Pc < 0.00001). The AIRE R257X and 13bpdel mutations were not observed in patients with PGA. The association of TNF-α; -308*A with PGA might be directly or indirectly due to the association with HLA-DRB1*03.

Schleswig: medieval leprosy on the boundary between Germany and Denmark.

Leprosy was a well-recognized and dreaded disease in medieval Europe. The disease is reported to have reached Germany with the Roman invasion and it was present in Scandinavia in the first centuries AD. This paper estimates and analyzes the frequency of leprosy among adult people buried in one of five medieval cemeteries in the city of Schleswig. Seven different dichotomous osteological lesions indicative of leprosy were analyzed, and it was possible to score at least one of these conditions on 350 adult skeletons (aged 15 or older). The scores were transformed to a statistic indicating the likelihood that the person to whom the skeleton belonged suffered from leprosy. It was found that the frequency of leprosy in the five cemeteries varied between 9 and 44%. Four of the five cemeteries showed frequencies ranging from 35 and 44% and with no statistically significant differences among them. The fifth cemetery showed a significantly lower frequency of leprosy (9%). The distribution of female age at death does not appear to be affected by leprosy status. This means that females experienced a considerably elevated risk of dying once they had contracted leprosy as the disease usually has a mid-adulthood age of onset. In four of the five cemeteries males with leprosy died in higher ages than men without leprosy--in two of the cemeteries the difference was statistically significant. This indicates that leprosy usually added less to the risk of dying among men than among women in medieval Schleswig.

Validation of the BIOPAC indirect calorimeter for determining resting energy expenditure in healthy free-living older people

The BIOPAC indirect calorimeter for measuring resting energy expenditure (REE) is less cumbersome than many other calorimeters. We tested the hypothesis that the BIOPAC calorimeter is as well suited for determining REE in older people as traditional calorimeters. In 50 healthy persons (24 men and 26 women; age range, 61-83 years), REE by BIOPAC was validated against Vmax Spectra indirect calorimeter as a criterion method. Resting energy expenditure by BIOPAC was recorded at 2 different time intervals to find optimal conditions for older persons. Also, REE by 7 published equations was validated. The Bland-Altman procedure was used to test agreement between methods. Multiple regression analysis was applied to develop a new equation for predicting REE from BIOPAC. The BIOPAC calorimeter and most empirical equations significantly overpredicted mean REE in both sexes. Mifflins equation best-predicted mean REE. Limits of agreement were wide for BIOPAC and narrow for most empirical equations. The Lührmann and Müller equations had smallest limits of agreement in men (+/-950 kJ/24 h) and the Harris-Benedict and Müller equations in women (+/-672 kJ/24 h). A new equation was developed for the BIOPAC device improving both predictions of mean and individual REE (R(2) = 0.671, standard error of the estimate = 136 kJ/24 h). Using this equation, 72.9% of subjects were lying within 10% of measured REE, compared with only 12.5% when using the manufacturers algorithm. In conclusion, the BIOPAC calorimeter is suitable for measuring REE in healthy older adults when the new prediction equation is applied. This calorimeter is not applicable to frail older persons.

Comparison of three segmental multifrequency bioelectrical impedance techniques in healthy adults

Background: The analysis of segmental or limb bioimpedance has gained importance in human population biology. However, standardized measurement techniques are needed. Aim: This study compared three techniques for segmental analysis (T1, conventional electrode measurement; T2, use of a novel additional switching unit; T3, equipotentials instead of switching unit) which are often used in population biology. Subjects and methods: The techniques were compared in 124 healthy adults (19–83 years) using a tetrapolar bioimpedance analyser (Nutriguard-M) at multiple frequencies (5, 50, 100 kHz) to gain whole-body and segmental resistances, reactances and phase angles. Results: Repeated measures ANOVA yielded a significant technique effect for most variables (26/27), a significant interaction technique × sex for half (13/27), and a significant interaction technique × age for a quarter (7/27) of variables. Conclusions: Differences exist between the three techniques which are primarily caused by inconsistent current pathways. A comparison with literature data showed that, in addition, subjects posture during measurement, electrode contact and electrode site may lead to inconsistent resistance and reactance values. This makes comparisons between different populations difficult. Therefore, this study recommends generally using the T2 technique which is standardized, easy to use and, thereby, well suited for field studies in large population groups.