The correlation of skin blood flow with age, total cholesterol, hematocrit, blood pressure, and hemoglobin

Normal skin blood flow at the deltoid region in 55 men whose ages ranged from 20 to 72 years was measured by the xenon-133 clearance method. In addition, the correlation of skin blood flow with age, systolic blood pressure, total cholesterol, hematocrit, hemoglobin, and total protein was analyzed by multiple regression analysis. The following results were obtained. Normal skin blood flow was found to decrease with increase in age, total cholesterol, and systolic blood pressure and showed a tendency to increase with elevation in hematocrit and hemoglobin values. Of the six parameters examined in the present study, the parameter that showed the strongest correlation with skin blood flow at the deltoid region was age, followed in decreasing order by total cholesterol, hematocrit, systolic blood pressure, and hemoglobin. It could therefore be concluded that age is the most reliable factor in clinically estimating skin blood flow. Furthermore, inasmuch as total cholesterol, hematocrit, systolic blood pressure and hemoglobin values also were correlated with skin blood flow, these values also should be taken in account in the synthetic evaluation of skin blood flow. It was skin blood flow at the deltoid region that was strongly correlated with age. This was followed by systolic blood pressure, hematocrit, and hemoglobin. Total cholesterol showed a weak correlation with age, but total protein did not demonstrate any correlation with skin blood flow and age. The results of the present study show that skin blood flow would be poor in the elderly and in patients with arteriosclerosis, hypertension, and anemia. Since it is suggested that the wound-healing process is delayed in such patients, utmost care should be exercised in treating their wounds.     

Rate of skin blood flow in various regions of the body.

Skin blood flow was measured by local clearance of 133Xe, and skin temperature was measured by medical thermography in various parts of the body. 1. A significant linear decrease in skin blood flow was observed with increasing age in the deltoid region. 2. The skin blood flow in the facial and pectoral areas was considerably higher than in the deltoid region. 3. The skin blood flow in the posterior cervical, lateral thoracic, lateral abdominal, and gluteal sites was less than in the deltoid region.     

Foot microcirculation and blood rheology in diabetes

Diabetes mellitus is associated with circulatory abnormalities. The blood flow in the skin of the dorsum of the foot and haemorheological variables were measured in 36 subjects. They were divided into three equal groups of diabetic patients: those with neuropathy, and both age and sex matched non-diabetic subjects; all were characterized by age, duration of diabetes and blood biochemistry. High and low shear rate blood viscosities were measured; aggregation was characterized using a Myrerene Aggregometer. The microcirculation in the skin of the dorsum of the foot was measured using a laser Doppler flowmeter. Measurements were made at room temperature with the subjects supine with the leg horizontal, and then with the lower leg vertical; the measurements were repeated at 42° C. Both diabetic groups had significantly increased low shear whole blood viscosity compared with normal subjects. The aggregation index was significantly greater in diabetic neuropaths than normal subjects. There were significant differences in the depth of vasomotor activity between the three groups, with the diabetic neuropaths commonly showing no motor activity at room temperature. The only significant correlations were between equilibrium laser Doppler values with the limb horizontal and both the low and high shear whole blood viscosities.     

Heat stress and age: Skin blood flow and body temperature

1. 1. The ability to increase skin blood flow is an important mechanism for transferring heat from the body core to the skin for dissipation.

2. 2. During exercise, skin blood flow is typically 20–40% lower in men and women aged 55 and over (compared with 20–30 years old) at a given body core temperature. Yet criterion measures of heat tolerance (changes in core temperature, heat storage) often show minimal or no age-related alterations. From a series of studies conducted in our laboratory over the past 5 years, the following conclusions can be drawn.

3. 3. When fit healthy older subjects are matched with younger subjects of the same gender, size and body composition, V_O2max, acclimation state, and hydration level, age-related differences in skin blood flow are evident. However, these differences often do not translate into “poorer” heat tolerance or higher core temperatures.

4. 4. The larger core-to-skin thermal gradient maintained by the older individuals allows for effective heat transfer at lower skin blood flows.

5. 5. Furthermore, there is an increased coefficient of variation for thermoregulatory response variables with increasing age.

6. 6. Despite differences in the mechanisms underlying thermoregulation, true thermal tolerance is less a function of chronological age than of functional capacity and physiological health status.

7. 7. While this conclusion is based primarily on cross-sectional studies, it is supported by the results of more recent studies using multiple regression analyses.

8. 8. Implicit in this conclusion is the notion that thermal tolerance, at any age, is a modifiable individual characteristic.

Peripheral circulation in the hand during natural ontogeny and under the conditions of prolonged graded traction

On the basis of the data of rheovasography (RVG) and laser Doppler flowmetry, comparative analysis of age-related changes in the peripheral blood circulation in hand tissues has been performed in 36 apparently healthy subjects aged 4–30 years and in 19 patients aged 18–50 years under the conditions of prolonged traction during surgical lengthening of finger bone stumps. The age-related changes in RVG are characterized by a higher volumetric blood content of tissues in children and adolescents, a decrease in the peripheral vascular tone, and wavelike recovery of capillary blood flow during reactive hyperemia, which is evidence for an unstable capillary tone. The dynamics of RVG indices during graded stretching in vivo (distraction) shows the dominance of an enhanced peripheral tone of arterioles and venules, and the response of the hand skin capillary bed to a 3-min ischemic test is analogous to the dynamics of indices of capillary blood flow in the hand skin of children.     

No effect of 85 mT permanent magnets on laser-Doppler measured blood flow response to inspiratory gasps

Although no effects of permanent magnets on resting skin blood flow (SBF) in humans have yet been demonstrated, the possibility that magnet related effects might modify dynamic SBF changes has not been previously studied. We hypothesized that magnets may alter local neurovascular mechanisms to cause changes in normal SBF vasoactive responses. To test this, we studied the effects of a magnet on SBF reductions induced by sympathetic reflexes associated with deep inspirations. SBF was continuously monitored by a dual channel laser-Doppler flowmeter with probes on the middle finger dorsum of both hands of 24 healthy subjects. In the first of two successive intervals, each of the fingers rested on sham ceramic magnets (control interval). Subsequently, one finger rested on an active magnet and the other finger on a sham (experimental interval). Skin temperatures were also measured. The magnet was a 37 mm diameter x 14 mm thick ceramic magnet with a surface field strength of 85 mT measured in the geometrical center of the magnet. Field strength at the finger dorsum, 13 mm above magnet, was 31.5 mT. During each interval, three deep breaths were used to elicit SBF reductions. Responses were calculated as the percent reduction in SBF from its prior 20 s average. Breaths in each interval were spaced 3 min apart to permit full recovery between responses. The experimental interval started after an active magnet was in place for 20 min. Results showed no significant difference in either vasoconstrictive responses or skin temperature due to the magnet. We conclude that magnets of the type, strength and duration used, have no significant effect on vasoconstrictive processes associated with this sympathetic reflex in this group of healthy subjects.     

Basic taste stimuli elicit unique responses in facial skin blood flow

Facial expression changes characteristically with the emotions induced by basic tastes in humans. We tested the hypothesis that the five basic tastes also elicit unique responses in facial skin blood flow. Facial skin blood flow was measured using laser speckle flowgraphy in 16 healthy subjects before and during the application of basic taste stimuli in the oral cavity for 20 s. The skin blood flow in the eyelid increased in response to sweet and umami taste stimuli, while that in the nose decreased in response to a bitter stimulus. There was a significant correlation between the subjective hedonic scores accompanying these taste stimuli and the above changes in skin blood flow. These results demonstrate that sweet, umami, and bitter tastes induce unique changes in facial skin blood flow that reflect subjective hedonic scores.     

Measurement of skin blood flow in delayed deltopectoral flaps, using local clearance of 133Xenon.

A study was made to determine the skin blood flow at the deltoid region in 89 cases, and the regional blood flow of delayed deltopectoral flaps, using the local clearance of 133Xe. The change in the skin blood flow, before and after a delay procedure of the deltopectoral flap, was measured in 27 patients--and the following results were obtained. (1) There was a linear tendency to a decreasing flow, one found to be statistically significant, with increasing age of the patient. (2) A significant correlation was found between the skin blood flow and the blood flow of the subcutaneous tissue. (3) The blood flow after we raised one side of a deltopectoral flap and lined it with a split-skin graft was higher than that found after a U-shaped undermining and not lining a flap. (4) The rate of successful transfer of a deltopectoral flap was found to be low when the 133Xe clearance rate was less than 0.07.     

Evaluation of the use of an integration-type laser-Doppler flowmeter with a temperature-loading instrument for measuring skin blood flow in elderly subjects during cooling load: comparison with younger subjects

An integration-type laser-Doppler flowmeter, equipped with a temperature-load instrument, for measuring skin blood flow (ILD-T), and analytical parameters developed in a previous study were used to compare changes in the skin blood flow in the forehead and cheek in elderly subjects (in their 60s and 70s) with those in younger subjects (in their teens to 50s). Age-related differences in skin blood flow in the forehead and cheek in response to cooling were evaluated in 90 healthy women in their teens to 70s (mean age: 17.2 +/- 0.33 years for teenagers; 24.3 +/- 0.76 years for those aged 20-29 years; 34.8 +/- 1.12 years for those aged 30-39 years; 43.3 +/- 0.78 years for those aged 40-49 years; 53.8 +/- 1.13 years for those aged 50-59 years; 63.5 +/- 0.55 years for those aged 60-69 years; 72.2 +/- 0.70 years for those aged 70-79 years). The measurement was performed continuously for 5 min: for 1 min at a sensor temperature of 30 degrees C, for 2 min after the setting of the sensor temperature had been changed to 10 degrees C, and for 2 min after the temperature setting had been cancelled. The parameters analyzed were (1) skin temperature in a resting state before measurement ( T(rest)), (2) mean skin blood flow in 1 min at a sensor temperature of 30 degrees C ( F(30 degrees C)), (3) minimum skin blood flow at a sensor temperature of 10 degrees C ( F(min)), (4) slope of the blood flow plot during the period from the beginning of cooling at 10 degrees C to F(min) ( S(fall)), (5) time required for the sensor temperature to reach 10 degrees C (Delta t(s)), (6) maximum skin blood flow during the period from the end of cooling to the end of measurement ( F(max)), (7) slope of the blood flow plot during the period from F(min) to F(max) ( S(rise)), (8) rate of decrease of the skin blood flow during cooling: FDR = ( F(min)/ F(30 degrees C))x100, (9) recovery rate of the skin blood flow after the end of cooling: FRR = ( F(max)/ F(30 degrees C))x100. When correlations among the above nine parameters were evaluated by combining all age groups, significant correlations ( P < 0.01) were observed between F(30 degrees C) and F(min), F(30 degrees C) and F(max), F(30 degrees C) and S(fall), F(min) and F(max), and F(max) and S(rise) in the forehead. In the cheek, significant correlations ( P < 0.01) were observed in all these combinations except between F(max) and S(rise). When these analytical parameters were compared among the age groups, F(30 degrees C), T(rest), F(max), and S(rise) decreased significantly ( P < 0.02 for F(30 degrees C) and T(rest), P < 0.01 for F(max) and S(rise)) and S(fall) increased significantly ( P < 0.03) in the forehead with aging. However, no significant change with aging was observed in FDR, Delta t(s), F(min), and FRR. In the cheek, FDR increased significantly ( P < 0.03), and S(rise) decreased significantly ( P < 0.01) with aging. However, no significant change with aging was observed in F(30 degrees C), T(rest), F(max), S(fall), Delta t(s), F(min), and FRR. Thus, the decrease in the skin blood flow during cooling showed no marked quantitative change with age, but, with aging, the rate of this decrease was clearly reduced in the forehead. In the cheek, on the other hand, the skin blood flow decreased markedly with aging, but no clear change was observed in the rate of this decrease. By using ILD-T and examining various parameters obtained, the skin hemodynamics in the forehead and cheek during cooling from 30 degrees C to 10 degrees C could be analyzed, and differences in the hemodynamics between the forehead and cheek and between elderly and younger individuals were clarified. This instrument is expected to be clinically useful.     

The cell kinetics of the epidermis and follicular epithelium of the rat: variations with age and body site

The skin from rats of differing age was used to quantify variations in the cell kinetics of the epidermis and the follicular epithelium of different body sites. Four parameters were assessed, namely the basal cell density (BCD), the labelling index (LI), the duration of DNA synthesis (ts) and the basal cell turnover time (tT). The BCDs of the epidermis of the dorsum and the upper surface of the foot were similar in rats of 7, 14 and 52 weeks of age, but there was an indication of a progressive decline with increasing age in the BCD of the epidermis of the ear and tail. There were no age-related changes in the length of ts in any of the four body regions. The rate of cell proliferation, as indicated by the values of the LI and tT, was relatively rapid in the epidermis of the dorsum, foot and tail of rats aged 7 weeks (LI greater than 12%; tT less than 80 h). In rats aged 14 weeks this rate of proliferation was maintained in the epidermis of the dorsum. However, in the foot and tail the rate of cell proliferation was decreased (LI less than 10%; tT greater than 85 h). A fall in the rate of proliferation of the epidermis of the dorsum was only seen in 52-week-old animals. In these animals the rates of proliferation in the foot and tail were similar to those at the age of 14 weeks. In the epidermis of the ear there was no appreciable change in the rate of cell proliferation with age. The values of the cell kinetic parameters varied in the different body sites. For example, in 52-week-old animals values for tT were relatively short in the epidermis of the tail and foot and appreciably longer in the epidermis of the dorsum and ear. Considered overall, values for the cell kinetic parameters of the epidermis were comparable with those for the follicular epithelium. The only major differences between the epidermis and the follicular epithelium were in the upper surface of the foot at 7 weeks of age, and in the tail at 7 and 14 weeks of age, where the LI was higher and the tT shorter in the epidermis than in the follicular epithelium. The relevance of the observed age- and body-site-related variations in the cell kinetics of the epidermis are discussed in relation to previously described differential changes in the radiosensitivity of the skin in this strain of rat.     

Differences in fecal microbiota in different European study populations in relation to age, gender, and country: a cross-sectional study

A cross-sectional study on intestinal microbiota composition was performed on 230 healthy subjects at four European locations in France, Germany, Italy, and Sweden. The study participants were assigned to two age groups: 20 to 50 years (mean age, 35 years; n = 85) and >60 years (mean age, 75 years; n = 145). A set of 14 group- and species-specific 16S rRNA-targeted oligonucleotide probes was applied to the analysis of fecal samples by fluorescence in situ hybridization coupled with flow cytometry. Marked country-age interactions were observed for the German and Italian study groups. These interactions were inverse for the predominant bacterial groups Eubacterium rectale-Clostridium coccoides and Bacteroides-Prevotella. Differences between European populations were observed for the Bifidobacterium group only. Proportions of bifidobacteria were two- to threefold higher in the Italian study population than in any other study group, and this effect was independent of age. Higher proportions of enterobacteria were found in all elderly volunteers independent of the location. Gender effects were observed for the Bacteroides-Prevotella group, with higher levels in males than in females. In summary, age-related differences in the microbiota makeup were detected but differed between the study populations from the four countries, each showing a characteristic colonization pattern.     

Biomarkers of antioxidant status and lipid peroxidation in elderly patients with hypertension

Objective: The objective of the present study was to examine selected parameters of the blood redox system in elderly patients with hypertension.examine selected parameters of the blood redox system in elderly patients with hypertension. Methods: We analyzed differences in redox-associated molecules and enzymes among elderly hypertensive subjects (age above 65?years, n?=?49) and two groups of normotensive subjects (<65 years old – Control group I; n?=?27, and >65 – Control group II; n?=?30). Results: Decreased activity of antioxidant enzymes, increased lipid peroxidation and reduced production of nitric oxide were observed in hypertensive subjects, compared to healthy younger controls, or those of the same age. In healthy controls, an age-related decrease in the production of nitric oxide and the activities of SOD-1 and GPx-1 was also evident. The pathology of hypertension was characterised by further, significant decreases in the values of these parameters. When the subgroups of females and males were compared to their respective controls, a compromised redox balance was observed that was more evident in female hypertensives. Discussion: Hypertension in elderly patients is accompanied by changes in biomarkers of antioxidant status and lipid peroxidation status, which significantly differ from those observed in healthy ageing subjects. Our study also suggests that the relationship of gender and changes in redox balance with regard to hypertension should be further explored.     

The Prevalence and Magnitude of Impaired Cutaneous Sensation across the Hand in the Chronic Period Post-Stroke

Sensation is commonly impaired immediately post-stroke but little is known about the long-term changes in cutaneous sensation that have the capacity to adversely impact independence and motor-function. We investigated cutaneous sensory thresholds across the hand in the chronic post-stroke period. Cutaneous sensation was assessed in 42 community-dwelling stroke patients and compared to 36 healthy subjects. Sensation was tested with calibrated monofilaments at 6 sites on the hand that covered the median, ulnar and radial innervation territories and included both glabrous (hairless) and hairy skin. The motor-function of stroke patients was assessed with the Wolf Motor Function Test and the upper-limb motor Fugl-Meyer Assessment. Impaired cutaneous sensation was defined as monofilament thresholds >3 SD above the mean of healthy subjects and good sensation was ≤3 SD. Cutaneous sensation was impaired for 33% of patients and was 40–84% worse on the more-affected side compared to healthy subjects depending on the site (p<0.05). When the stroke patient data were pooled cutaneous sensation fell within the healthy range, although ∼1/3 of patients were classified with impaired sensation. Classification by motor-function revealed low levels of impaired sensation. The magnitude of sensory loss was only apparent when the sensory-function of stroke patients was classified as good or impaired. Sensation was most impaired on the dorsum of the hand where age-related changes in monofilament thresholds are minimal in healthy subjects. Although patients with both high and low motor-function had poor cutaneous sensation, overall patients with low motor-function had poorer cutaneous sensation than those with higher motor-function, and relationships were found between motor impairments and sensation at the fingertip and palm. These results emphasize the importance of identifying the presence and magnitude of cutaneous sensory impairments in the chronic period after stroke.     

Decline of tactile acuity in aging: a study of body site,blood flow,and lifetime habits of smoking and physical activity

Tactile acuity of 60 older subjects (≥?65 years) and 19 younger subjects (18–28 years) was assessed by two-point gap thresholds at the upper and lower surfaces of the forefinger, at the upper and lower surfaces of the feet, and at the volar surface of the forearm. The older subjects were assigned to one of four groups of 15 subjects each, depending on reported lifetime habits of physical activity and smoking: (1) active smokers, (2) active nonsmokers, (3) inactive smokers, and (4) inactive nonsmokers. Peripheral blood flow was assessed at the forefinger, foot, and forearm by means of laser-Doppler imaging and skin temperature recordings, under resting conditions and during and after a 5-min exposure to mild cooling (28°C). Consistent with previous studies, tactile acuity thresholds in the foot and finger averaged about 80% higher in the older subjects than in the younger subjects, but only about 22% higher in the forearm. Although the upper surface of the fingertip was more sensitive than the lower surface in both younger and older subjects, the age-related decline in tactile acuity was nearly identical on both sides of the finger and foot. The latter finding refutes the hypothesis that the larger effect of aging in the extremities results from greater physical wear and tear on the contact surfaces of the hands and feet. Self-reported lifetime histories of physical activity and smoking were not significantly associated with measures of cutaneous blood flow or tactile thresholds. Possible reasons for this lack of association are discussed, including the inherent limitations of testing only healthy older subjects, and the concept of “successful aging”.     

Effects of permanent magnets on resting skin blood perfusion in healthy persons assessed by laser Doppler flowmetry and imaging

Effects on skin blood perfusion of permanent ceramic magnets [0.1 T (1000 G) surface field], individually (disk shaped, 4 cm diameter x 1 cm thick) or in the form of a 11 x 7 in pad ( approximately 28 x 17.8 cm) with an array of 16 rectangular magnets (4.5 x 2.2 cm), were investigated in 16 female volunteers (27.4 +/- 1.7 years, range 21-48 years) using three separate protocols. In protocol A, a disk magnet was placed on the palmar surface of the hand in contact with the thenar eminence (n = 5). In protocol B, the magnet was placed on the hand dorsum overlying the thenar eminence (n = 5). In protocol C, the entire palm and fingers rested on the magnetic pad (n = 6). Magnets were in place for 36 min on one hand, and a sham was in place on the other hand. Blood perfusion was measured on the middle finger dorsum by laser Doppler flowmetry (LDF) and on the index finger by laser Doppler imaging (LDI). Perfusion measurements were simultaneously taken in sham and magnet exposed hands, before and during the entire magnet exposure interval. Magnetic field effects were tested by comparing skin blood perfusion sequences in magnet and sham exposed regions. Results showed no significant changes in either LDF or LDI perfusion at magnet or sham sites during exposure, nor were there any significant differences between sham and magnet sites for any protocol. Measurements of skin temperature at the LDF measurement sites also showed no significant change. It is concluded that in the healthy subjects studied with normal, unstressed circulation, magnets of the type and for the duration used, showed no detectible effect on skin blood perfusion in the anatomical area studied.     

Decline of tactile acuity in aging: a study of body site, blood flow, and lifetime habits of smoking and physical activity

Tactile acuity of 60 older subjects (> or = 65 years) and 19 younger subjects (18-28 years) was assessed by two-point gap thresholds at the upper and lower surfaces of the forefinger, at the upper and lower surfaces of the feet, and at the volar surface of the forearm. The older subjects were assigned to one of four groups of 15 subjects each, depending on reported lifetime habits of physical activity and smoking: (1) active smokers, (2) active nonsmokers, (3) inactive smokers, and (4) inactive nonsmokers. Peripheral blood flow was assessed at the forefinger, foot, and forearm by means of laser-Doppler imaging and skin temperature recordings, under resting conditions and during and after a 5-min exposure to mild cooling (28 degrees C). Consistent with previous studies, tactile acuity thresholds in the foot and finger averaged about 80% higher in the older subjects than in the younger subjects, but only about 22% higher in the forearm. Although the upper surface of the fingertip was more sensitive than the lower surface in both younger and older subjects, the age-related decline in tactile acuity was nearly identical on both sides of the finger and foot. The latter finding refutes the hypothesis that the larger effect of aging in the extremities results from greater physical wear and tear on the contact surfaces of the hands and feet. Self-reported lifetime histories of physical activity and smoking were not significantly associated with measures of cutaneous blood flow or tactile thresholds. Possible reasons for this lack of association are discussed, including the inherent limitations of testing only healthy older subjects, and the concept of "successful aging".     

Sex- and age-related blood pressure response to dynamic work with small muscle masses

Four groups of subjects of different ages and sex (group I: 20-29 years, women; group II: 20-29 years, men; group III: 30-39 years, women; group IV: 30-39 years, men) undertook dynamic one-hand work (load range 40%-80% of maximum voluntary contraction, at 60 working cycles/min) to allow a study of cardiovascular responses as shown by the resultant changes in blood pressure and heart rate. During fatiguing dynamic one-hand work, there was a large increase in systolic and diastolic blood pressures in both sexes after a few minutes. For all load levels, the systolic blood pressure was found to be higher by about 4 kPa in men (groups II and IV) than in women (groups I and III). Other age-related differences became evident in the diastolic blood pressure changes. The values obtained for the older groups were higher than those in the two younger groups. These differences in blood pressure response are possibly due to sex-related differences in the release of catecholamines, or to age-related organic changes in the vessels.     

Effects of a cool environment on the health of female office workers and students

OBJECTIVE: The aim of this study was to evaluate the effect of a cool environment on the peripheral skin blood flow and subjective thermal sensations of female office workers and female students. METHODS: The subjects were 26 female bank employees (mean age, 38 years) who worked in a cool environment and 10 female college students (mean age, 22 years). The peripheral skin blood flow was measured using a laser Doppler blood flow meter. In each bank employee, peripheral skin blood flow was measured at three time points during the workday in the medical treatment room at their workplace. In the college students, peripheral skin blood flow was measured every hour between 9:00 and 17:00 in a laboratory. In both the medical treatment room and the laboratory, the room temperature was controlled at 24-26 degrees C with a relative humidity of 55+/-10%. The bank employees and students were each divided into those with hypersensitivity to cold (Group A) and those without hypersensitivity to cold (Group B). RESULTS: When the 10 college students were in the cool environment (24-26 degrees C), their peripheral skin blood flow generally decreased over time. The rate of decrease of this blood flow was greater in Group A than in Group B. In the female bank employees, the peripheral skin blood flow was the lowest at 12:00 (before lunch), was increased at 13:00 (after lunch), and then was decreased at 17:30. However, the degree of the increase from before lunch to after lunch in Group A was about half of that in Group B. CONCLUSION: Among female office workers and students, a cool environment reduced the peripheral skin blood flow of individuals with hypersensitivity to cold to a greater degree than in those without hypersensitivity to cold.     

Relationships between bone and skin atrophies during aging.

Bone mineral density (BMD) was measured in 133 female subjects (age: 61.7 +/- 16.3 years) by dual energy X-ray absorptiometry (DEXA). Vertebral bone mineral density (BMD; L1-L4) and BMD of the whole upper femoral extremity were taken into account. In addition, skinfold thickness was measured with a callipers on the dorsum of the nondominant hand. A significant negative correlation was found between skinfold thickness and age (r = -0.623, p less than 0.0001). Both vertebral and femoral BMD decreased with age and the slopes were similar to those observed by other authors. Skinfold thickness was significantly correlated with vertebral (r = 0.364, p less than 0.0001) and femoral BMD (r = 0.486, p less than 0.0001). Skin and bone are connective tissues whose extracellular matrix mainly contains type I collagen. It is postulated that age-related skin atrophy and bone atrophy have a common genetic mechanism. Skinfold thickness measurement may help in defining the women at risk for osteoporotic bone fractures who should be referred for a DEXA examination.     

Age-related somatic structural changes in the nuclear genome of human blood cells

Structural variations are among the most frequent interindividual genetic differences in the human genome. The frequency and distribution of de novo somatic structural variants in normal cells is, however, poorly explored. Using age-stratified cohorts of 318 monozygotic (MZ) twins and 296 single-born subjects, we describe age-related accumulation of copy-number variation in the nuclear genomes in vivo and frequency changes for both megabase- and kilobase-range variants. Megabase-range aberrations were found in 3.4% (9 of 264) of subjects ≥60 years old; these subjects included 78 MZ twin pairs and 108 single-born individuals. No such findings were observed in 81 MZ pairs or 180 single-born subjects who were ≤55 years old. Recurrent region- and gene-specific mutations, mostly deletions, were observed. Longitudinal analyses of 43 subjects whose data were collected 7-19 years apart suggest considerable variation in the rate of accumulation of clones carrying structural changes. Furthermore, the longitudinal analysis of individuals with structural aberrations suggests that there is a natural self-removal of aberrant cell clones from peripheral blood. In three healthy subjects, we detected somatic aberrations characteristic of patients with myelodysplastic syndrome. The recurrent rearrangements uncovered here are candidates for common age-related defects in human blood cells. We anticipate that extension of these results will allow determination of the genetic age of different somatic-cell lineages and estimation of possible individual differences between genetic and chronological age. Our work might also help to explain the cause of an age-related reduction in the number of cell clones in the blood; such a reduction is one of the hallmarks of immunosenescence.