SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Metacarpal cortical thickness has been measured in a sample of 47,XXY men and two control samples of 46,XY men and 46,XX women in the age range 20-70. The results suggest that in this age range cortical thickness in 47,XXY men is more similar to that of normal women than normal men.
Metacarpal cortical thickness was measured in 83 patients with chronic renal failure undergoing periodic hemodialysis. Patients were dialyzed twice weekly, 8--9h per session, with a calcium concentration in dialysate of 6.5 mg/dl. Supplements of calcium, vitamin D (5,000 I.U. a day), steroid anabolic hormones, and aluminium hydroxyde were administered to all patients. They were on a normal protein intake and unrestricted physical activity. The results show that the young males have a reduction in cortical thickness as compared to age-matched controls, and that there is a progressive loss in cortical width as the length of dialysis increases. This bone loss is statistically significant in males during their first 18 months of dialysis.
Reproducibility of estimates of cortical bone quantity in the appendicular skeleton by two methods was studied in healthy individuals and patients undergoing long-term hemodialysis. Repeated measurements of cortical thickness (CT) at the midpoint of the second metacarpal were taken from single radiographs of both hands by two independent observers. Repeated measurements by the same observer were more reproducible and the degree of reproducibility was far greater in healthy subjects than in dialysis patients. Repeated measurements were made of bone mineral content (BMC) and bone width (W) of the distal radius by photon absorptiometry. Repeated BMC/W determinations were highly reproducible in both healthy subjects and dialysis patients. High correlation was found between BMC and cross-sectional cortical area and between both simple cortical thickness and cortical area/width. Thus the photon absorptiometric technique is superior for the serial monitoring of bone quantity, particularly in patients with uremic osteodystrophy, but results obtained by the two methods in group studies should be comparable.
Bone cortical thickness and density were measured in rat femurs in vitro by a photon absorptiometry technique. A scan perpendicular to the long bone axis using photons from highly collimated 109Cd or 125I sources yielded the bone wall thickness and attenuation at mid-shaft. A second scan after the bone was rotated axially 90 degrees was taken to measure the wall or shaft thickness identically responsible for the mid-shaft attenuation of the first scan. The mid-shaft attenuation of the second scan was due to the bone thickness derived from the first scan; thus two complementary measurements are derived by this technique. The bone density is then directly calculated with an estimated accuracy of 10% (coefficient of variation) using empirically determined mass attenuation coefficients. Measurements of mass attenuation coefficients of ashed and dried samples were compared with calculated coefficients for estimated bone composition. Results indicate that the mass attenuation coefficient for bone in vivo can be well estimated such that bone density can be accurately derived from this technique.
The nature of K exit across the basolateral membrane of rabbit cortical thick ascending limb (CTAL) was investigated using the patch clamp technique. The basolateral membrane was exposed by mild collagenase treatment (0.1 U/ml), and a K-selective inwardly rectifying channel was identified. In cell-attached patches (140 mM K pipette) the inward conductance was 35.0 +/- 1.3 pS (n = 9) compared with an outward conductance of 7.0 +/- 0.9 pS (n = 5), and the current reversed at a pipette potential of -63.5 +/- 3.1 mV (n = 9). The channel is strongly voltage dependent, showing an e-fold increase in open probability per 18-mV depolarization. Barium blocked the channel, reducing both mean open probability and single-channel current amplitude; however, the channel was not Ca sensitive. On excision the channel exhibited rundown, which could not be prevented by 0.1 mM ATP or ATP plus 20 U/ml catalytic subunit of protein kinase A. A few excised patch recordings were possible, which confirmed the presence of a highly K-selective channel with a K-to-Na permeability ratio of 100. In conclusion, 1) it is possible to obtain patch clamp recordings from the rabbit CTAL basolateral membrane using a very mild collagenase treatment, and 2) the exit of K across the basolateral membrane is mediated at least in part by the presence of voltage-sensitive K channels.
Twenty-seven non-infected delayed union or non-union fractures of the shaft of the tibia in 26 patients were operated on with a full cortical thickness inlay graft taken from the injured leg. The initial trauma was moderate in 9 fractures and severe in 18. Fifteen fractures were closed injuries and 12 open. The fracture pattern was longitudinal in 5 cases, transverse in 11 and communited in 11. Surgery was performed 12 to 72 weeks (mean: 30 weeks) after the fractures had been sustained. All fractures healed after the bone grafting procedure. The time until union was established after surgery ranged from 6 to 37 weeks (mean: 17 weeks). The healing time was neither influenced by the initial type of fracture pattern (p > 0.05) nor by the fracture age at surgery (r = -0.21). Of 13 patients re-examined 8 to 16 years after surgery, the clinical results were classified as excellent in 8, as fair in 2, and as poor in 3 patients.
A recent study using the photon absorption technique has revealed a high frequency of significant bone loss in diabetic adults regardless of age or duration of diabetes. In this study 107 diabetic children age 4-18 were studied using cortical bone thickness and skeletal maturation as indicators of bone development. Overall, 25% of all diabetic children had cortical thickness values below the five percent limit for normal children. This was more common in boys than girls and was unrelated to duration of diabetes. A modest increase in delayed skeletal maturation did not account for the cortical thinning and osteopenia observed. The cause of the osteopenia of diabetic children remains an enigma.
The visual cortex of adult rats is sexually dimorphic at both the gross size and dendritic levels [Brain Res., 295 (1984) 27-34; J. Comp. Neurol., in press]. In addition, sex differences in the dendritic tree are dynamic and can be altered by environmental conditions imposed at weaning [Brain Res., 295 (1984) 27-34]. The present study examines sex differences in cortical thickness and in the dendritic tree of the monocular (Oc1M) and binocular (Oc1B) subfields in littermate male and female pairs of Long-Evans rats at weaning age (25 days). From Nissl-stained tissue, it was found that the whole cortex and layer II-IV of Oc1B was thicker in males than females. No sex differences were found in the thickness of Oc1M. Golgi-Cox-stained pyramidal neurons in layer III from the Oc1M and Oc1B regions were quantified in 7 littermate pairs of weaning-age rats. There were no sex differences in the basilar tree, while the apical oblique branches were sexually dimorphic, especially in the monocular region. Females had greater total dendritic length and longer terminal branches in Oc1M compared to males. Females also had longer bifurcating branches in both Oc1M and Oc1B than males. The present study found that sex differences at weaning age do not completely mirror the dimorphisms found in the visual cortex of the adult rat. This study also indicates that related subfields can differ in their morphology and should be examined separately.
Three groups of Ugandan children, 18 in each group, and one comparison group of 18 children were examined at 11-17 years of age. The three groups had previously been admitted for treatment of protein energy malnutrition between the ages of 8 to 15, 16 to 21 and 22 to 27 months respectively. The comparison group had not been clinically malnourished throughout the period up to 27 months of age. The children came from one tribe and from similar socio-economic background, and were individually matched on age and sex. The bone age was estimated by hand wrist radiography scored for maturity by the Tanner & Whitehouse method. The metacarpal index, a ratio derived from the medullary width and full diameter of the mid-point of the second metacarpal, was used as a measure of bone cortical thickness. The three malnourished groups are significantly shorter in height than the comparison group, but are not different in bone age and metacarpal index. No differences are observed between the three groups of children who had been admitted for protein energy malnutrition at different ages. The findings are discussed as they relate to the existing literature.
The bone mineral content in the shafts of the forearm in 17 women with cervical fracture of the upper end of the femur was low. The cortex of the femoral neck was also lower than normal. Thus women with hip fractures at an early age may have lower than average total skeletal tissue density. This may be due not simply to systemic osteoporosis but possibly to constitutionally thin bone cortices.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
To better understand the intra-uterine bone modelling and remodelling process in small-for-gestational-age (SGA) newborn infants, long bone growth was studied using postmortem X-ray films in a group of such infants (n = 34). Bone length, diaphyseal diameter, medullary diameter, cortical thickness, cortical area, the Barnett-Nordin index, and the percentage of cortical area were determined in femur, tibia, and humerus. A separate group of appropriate-for-gestational-age (AGA) newborn infants (n = 146) was used as controls. Length and cortical bone mass in all three bones were significantly lower in SGA infants than in AGA infants. Decreased cortical bone mass in SGA infants was the result of decreased diaphyseal diameters and increased medullary diameters. Similar results were obtained when SGA infants were subclassified as preterm and term and compared with the control group of AGA infants. Bone lengths and diaphyseal diameters in SGA infants did not differ from those observed in a weight-matched control group of AGA infants although the latter were younger by 4 weeks' gestation. However, the cortical bone mass was lower than in the control group because of the relative greater medullary diameters in all three long bones in the SGA infants. Our present results indicate that reduced cortical bone mass in SGA infants is a mixed growth modelling and remodelling dependent process.
Measurements were made on hand radiographs of normal girls and patients with Turner's syndrome. Normal girls going through puberty display increases in hand bone dimensions which are highly correlated with height and bone age. We report such changes in length and total bone width of metacarpal II (MCII) and proximal phalanx II (PPII), and in combined cortical thickness and cortical area of MCII. For the relative cortical area, the correlations are less pronounced. In comparison with controls of similar height, MCII of patients with Turner's syndrome has greater length and total bone width and combined cortical thickness. Turner patients treated with sex steroids undergo skeletal maturation as well as a rise in MCII relative cortical area (a measure of bone density), but fail to show a commensurate increase in MCII length and in MCII cortical area (a measure of bone mass). It is concluded that in untreated Turner patients, bone density as well as bone mass are normal for the (retarded) bone age, and that sex steroids which promote skeletal maturity likewise raise bone density but not bone mass. The (relative) insensitivity of bone mass and the lack of accelerated statural growth in response to administered sex steroids may be inborn characteristics of the Turner skeleton.
This study examined the estimation of age at death from the second metacarpal in 227 individuals aged 30-98 years. Variables ascertained from each bone were: cortical thickness and microdensitometric cortical bone density measured on radiographs of the bone and total osteon count and density recorded on microradiographs of the complete cross section at its midshaft. Based on the latter two variables, two age groups were formed; a middle age group representing those individuals aged 30-65 years, and an older group aged 65+. Stepwise regression analysis of the four variables produced a series of regression equations for age estimation for the middle, old and combined age groups for each sex and sexes combined. Sex-specific equations provided better results than nonspecific ones, especially in females. Total osteon density and combined cortical thickness were found to be the most useful estimators in the middle and the old age group, respectively. The standard error of estimate was 6.71 and 6.90 years in each age group for the sexes combined. In the combined age group, age could be estimated accurately from total osteon count, cortical thickness and MD cortical bone density with the standard error of estimate of 11.10 years. The relative error of estimate ranged within +/- 30% in almost all individuals aged above 60 years.
The sexual dimorphism in second metacarpal bone growth was investigated in 710 malnourished Guatemalan children one to seven years old to determine if the sex differences seen are only the result of differences in stature and weight. The study sample was mixed-longitudinal and consisted of 1,586 annual examinations. Boys have greater mean stature, weight, periosteal diameter, medullary diameter and cortical area than girls the same age, while girls have greater age specific mean cortical thickness and percent cortical area than boys. When the effects of stature, weight and age are removed boys still have significantly larger periosteal and medullary diameters and less cortical thickness and percent cortical area than girls. These differences between boys and girls therefore cannot be explained by sex differences in body size. However, no sex differences in cortical area remain after accounting for differences in stature, weight and age.