Determinants of the first decade of bone loss after menopause at spine, hip and radius

This study documented bone loss at three different sites in the early postmenopausal period, and examined potential predictors. Forty-three women underwent repeated measurements of bone density at the lumbar spine, proximal femur and distal radius for up to 14 years. Individual rates of bone loss were calculated for the spine and hip; for radial trabecular bone, rates were calculated separately for two time periods, earlier and later after menopause. In the spine and radius, initially high rates of loss diminished with time after menopause. No positive correlations for bone loss were found between the three sites, suggesting that faster than average bone loss was specific to individual bones. High body mass index (BMI) was significantly protective against fast bone loss at the spine and radius; in the spine, each unit increase in BMI was associated with a approximately 5% reduction in the rate of bone loss. Of the other variables measured (maximum oxygen consumption, lean body mass, fat mass, mean psoas muscle area at the L3 level, hand grip strength as well as anthropometry) only bone densitometry was sufficiently predictive to help guidance on hormone replacement or other prophylactic therapy. The data suggest that the known relationship between excessive leanness and risk of osteoporosis and vertebral fracture after menopause might in part be due to fast post-menopausal bone loss. Because bulk of psoas muscle was associated with low spine loss rates, the data also support a role for applied muscular loading in local maintenance of bone density.     

Estimation of whole body bone resorption rate: a comparison of urinary total hydroxyproline excretion with two radioisotopic tracer methods in osteoporosis

In 37 female patients with primary osteoporosis, urinary hydroxyproline excretion, determined in 18 24-h consecutive complete urine collections was compared with two radioisotopic measurements of bone resorption rate measured simultaneously using 85Sr. A somewhat better fit was obtained when the kinetically determined bone resorption rate was corrected for long-term exchange processes within bone. Regression analysis showed that the intercept of the regression of hydroxyproline excretion on resorption rate, corrected or uncorrected for exchange, was significantly higher than zero at about 100 mumol/day. This is consistent with a substantial fraction of urinary hydroxyproline arising from non-bony sources. Fifteen paired studies were analysed and the results suggested that intra-individual variability in these relationships (when studies were separated by a year or more) were similar to inter-individual variability. We calculated the precision with which an estimate of bone resorption could be determined based on the calculated regressions. As a means of non-invasive quantitation of whole body bone resorption rate, the excretion rate of hydroxyproline, measured over 5 days, for example, appeared competitive with isotopic methods making no correction for exchange and relatively little worse than our exchange corrected method.     

Grip strength measurement for frailty assessment in patients with vascular disease and associations with comorbidity,cardiac risk,and sarcopenia

Objective

Frailty is associated with adverse events, length of stay, and nonhome discharge after vascular surgery. Frailty measures based on walking-based tests may be impractical or invalid for patients with walking impairment from symptoms or sequelae of vascular disease. We hypothesized that grip strength is associated with frailty, comorbidity, and cardiac risk among patients with vascular disease.

Ultrasonic grey scale visualization of the thyroid gland

Ultrasonic examination of the thyroid provides an accurate method of differentiating between solid and cystic lesions. With grey scale echography contents of many solid lesions give rise to a characteristic echo pattern which may eventually allow the ultrasonic classification of these lesions. This preliminary study of 40 patients presents the echograms associated with some of the more common pathological conditions of the thyroid gland.     

The Role of Catheter Ablation Techniques in the Treatment of Classic (Type 1) Atrial Flutter

Several attempts at circuit interruption of type 1 atrial flutter by means of surgical or catheter techniques have been published. We recently reported the results of a series of patients who underwent catheter fulguration of the low septal right atrium, with a mean follow-up of almost 3 years. True electrophysiological success was observed in 7/14 patients (50%). Clinical success, defined as absence of symptoms, was observed in 8/14 (57%) in this patient population. No serious complications were encountered, but the potential risks of DC shock, and the experience that we gained in right atrial mapping using this approach, led us to reconsider the role of atrial DC ablation in these patients. Additional studies assessing the meaning of fragmented electrograms, and identification of one for of severall slow conduction areas of the reentrant circuit are ongoing.     

Acquired hemolytic anemia due to "auto"-anti-A or "auto"-anti-B induced by group O homograft in renal transplant recipients

Three patients developed severe but self-limited hemolytic anemia within 2 weeks of renal transplantation. All three had received kidneys from cadaver donors who were blood group O. Two of the recipients were blood group B while the third was blood group A. There was no pretransplant preparation of the donors or the recipients. Preoperative crossmatch and antibody screen were negative; however, subsequent to the hemolytic episodes, group-specific blood was incompatible and the patients were transfused with group O crossmatch-compatible blood. Blood bank serological tests showed a positive direct antiglobulin test (DAT), and anti-A and anti-B were eluted from group A and B patients, respectively. There was no evidence of hemolysis despite the positive DAT at 37 days following transplantation in two of the three patients who were maintained on cyclosporine immunosuppression. Retrospective analysis of renal transplant records showed that these "autoantibodies" appeared in three of the four renal transplant recipients who were on an immunosuppressive regimen of cyclosporine , with or without prednisone, but not in the 21 recipients who received radiotherapy to the donor kidney in addition to cyclosporine or azathioprine (p = less than 0.001). The possible pathogenetic mechanism for "autoantibody" formation by donor kidney and the role of immunosuppressive agents are discussed.     

The clinical measurement of skeletal blood flow.

1. A new method for measurement of skeletal blood flow is described which depends on the complete extraction of 18F in a single passage through bone. 2. Plasma concentration and urinary excretion are measured over a 2 h period. The technique of impulse analysis is used to determine the initial transfer rate of 18F to bone and extravascular extracellular fluid (ECF). The ECF component is evaluated by using a second tracer (51 Cr-EDTA or 82Br) and the bone transfer rate obtained by difference. The 51Cr-EDTA data also provide an estimate of glomerular filtration rate and enable a correction to be applied for urinary bladder retention when necessary. 3. Duplicate measurements of skeletal blood flow in eight normal male volunteers gave mean flows between 4-4 and 5-9% of blood volume/min, or about 4 ml min-1 100 g-1 of bone. The variation between normal subjects was least when the results were expressed as % of blood volume/min rather than ml/min, ml min-1 kg-1 or ml min-1 1-73 m-2 body surface area. The precision of the technique was estimated to be 16-4%. 4. Addition of 1-5% random noise to the input data resulted in an uncertainty of 8-5% in the measurement of skeletal blood flow, suggesting that improved precision depends on closer control of physiological variables. 5. In six patients with severe untreated Paget's disease of bone, skeletal blood flow was 8-4-15-3% of blood volume/min. The increase was significant in all cases. 6. The absorbed radiation dose is low, so that the measurement can be repeated.     

O2 sensing is preserved in mice lacking the gp91 phox subunit of NADPH oxidase.

The rapid response to hypoxia in the pulmonary artery (PA), carotid body, and ductus arteriosus is partially mediated by O2-responsive K+ channels. K+ channels in PA smooth muscle cells (SMCs) are inhibited by hypoxia, causing membrane depolarization, increased cytosolic calcium, and hypoxic pulmonary vasoconstriction. We hypothesize that the K+ channels are not themselves "O2 sensors" but rather respond to the reduced redox state created by hypoxic inhibition of candidate O2 sensors (NADPH oxidase or the mitochondrial electron transport chain). Both pathways shuttle electrons from donors, down a redox gradient, to O2. Hypoxia inhibits these pathways, decreasing radical production and causing cytosolic accumulation of unused, reduced, freely diffusible electron donors. PASMC K+ channels are redox responsive, opening when oxidized and closing when reduced. Inhibitors of NADPH oxidase (diphenyleneiodonium) and mitochondrial complex 1 (rotenone) both inhibit PASMC whole-cell K+ current but lack the specificity to identify the O2-sensor pathway. We used mice lacking the gp91 subunit of NADPH oxidase [chronic granulomatous disease (CGD) mice] to assess the hypothesis that NADPH oxidase is a PA O2-sensor. In wild-type lungs, gp91 phox and p22 phox subunits are present (relative expression: macrophages > airways and veins > PASMCs). Deletion of gp91 phox did not alter p22 phox expression but severely inhibited activated O2 species production. Nonetheless, hypoxia caused identical inhibition of whole-cell K+ current (in PASMCs) and hypoxic pulmonary vasoconstriction (in isolated lungs) from CGD vs. wild-type mice. Rotenone vasoconstriction was preserved in CGD mice, consistent with a role for the mitochondrial electron transport chain in O2 sensing. NADPH oxidase, though a major source of lung radical production, is not the pulmonary vascular O2 sensor in mice.     

DNA "fingerprinting" reveals high levels of inbreeding in colonies of the eusocial naked mole-rat.

Using the technique of DNA fingerprinting, we investigated the genetic structure within and among four wild-caught colonies (n = 50 individuals) of a eusocial mammal, the naked mole-rat (Heterocephalus glaber; Rodentia: Bathyergidae). We found that DNA fingerprints of colony-mates were strikingly similar and that between colonies they were much more alike than fingerprints of non-kin in other free-living vertebrates. Extreme genetic similarity within colonies is due to close genetic relationship (mean relatedness estimate +/- SE, r = 0.81 +/- 0.10), which apparently results from consanguineous mating. The inbreeding coefficient (F = 0.45 +/- 0.18) is the highest yet recorded among wild mammals. The genetic structure of naked mole-rat colonies lends support to kin selection and ecological constraints models for the evolution of cooperative breeding and eusociality.     

A UK Consensus Group on management of glucocorticoid-induced osteoporosis: an update

Abstract. Eastell R, Reid DM, Compston J, Cooper C, Fogelman I, Francis RM, Hosking DJ, Purdie DW, Ralston SH, Reeve J, Russell RGG, Stevenson JC, Torgerson DJ (University of Sheffield Medical School, Sheffield; University of Aberdeen, Aberdeen; University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Cambridge; Southampton General Hospital, Southampton; Guy's Hospital, London; Freeman Hospital, Newcastle upon Tyne; Nottingham City Hospital, Nottingham; Hull Royal Infirmary, Hull; Wynn Institute for Metabolic Research, London; and the University of York, York, UK). A UK Consensus Group on management of glucocorticoid-induced osteoporosis: an update (Review). J Intern Med 1998; 244: 271–292.
In the UK, over 250 000 patients take continuous oral glucocorticoids (GCs), yet no more than 14% receive any therapy to prevent bone loss, a major complication of GC treatment. Bone loss is rapid, particularly in the first year, and fracture risk may double. This review, based wherever possible on clinical evidence, aims to provide easy-to-use guidance with wide applicability. A treatment algorithm is presented for adults receiving GC doses of 7.5 mg day⁻¹ or more for 6 months or more. General measures, e.g. alternative GCs and routes of administration, and therapeutic interventions, e.g. cyclical etidronate and hormone replacement, are recommended.