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  • Electronic Resource  (8)
  • Cell & Developmental Biology  (3)
  • Ferrocyanide Method  (3)
  • Risk factors  (2)
  • 1
    ISSN: 1433-2965
    Keywords: Bone density ; Prospective studies ; Risk factors ; Vertebral fracture incidence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated the ability of bone density and vertebral fractures at baseline to predict vertebral fracture incidence in a cohort of postmenopausal women with osteoporosis. The study population was 380 postmenopausal women (mean age 65 years) treated for osteoporosis in a randomized, placebo-controlled, clinical trial of the bisphosphonate etidronate at seven geographic centers in the United States. Baseline measurements of bone mineral density were obtained in 1986 by quantitative computed tomography at the spine and dual-photon absorptiometry at the lumbar spine and hip. Vertebral fractures were documented on serial spine radiographs. Proportional hazards models were used to evaluate the ability to predict the risk of subsequent fractures during an average of 2.9 years of follow-up. Presence of one or two fractures increased the rate of new vertebral fractures 7.4-fold (95% confidence interval = 1.0 to 55.9). Additional fractures at baseline further increased the fracture rate. A decrease of 2 standard deviations in spinal bone density by absorptiometry was associated with a 5.8-fold increase in fracture rate (95% confidence interval = 2.9 to 11.6). The lowest and highest quintiles of bone density had absolute fracture rates of 120 and 6 cases per 1000 patient-years, respectively. In general, the simultaneous use of two predictors (bone density and prevalent fractures or two bone density measurements) improved fracture prediction, compared with the use of a single predictor. We conclude that both bone density and prevalent vertebral fractures are strong, complementary predictors of vertebral fracture risk. The results suggest that physicians can use bone density and prevalent vertebral fractures, individually or in combination, as risk factors to identify patients at greatest risk of new fractures.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Osteoporosis international 4 (1994), S. 1-5 
    ISSN: 1433-2965
    Keywords: Bone mass ; Bone density ; Fracture incidence ; Fracture prevalence ; Longitudinal studies ; Risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A prospective cohort study of 1098 postmenopausal Japanese-American women evaluated the relationship between baseline non-spine fractures and new (incident) spine fractures. At the baseline examination in 1981, prevalent non-spine fractures were ascertained by interview, and prevalent spine fractures by radiograph. Bone mass measurements of the distal radius, proximal radius, calcaneus (1981), the lumbar spine (1984) were obtained and repeated at 1- to 2-year intervals. Women with existing non-spine fractures have a threefold greater risk of subsequent spine fractures, independent of bone mass, and independent of the known association between prevalent spine fractures and subsequent spine fractures. Women with both a prevalent non-spine fracture and low bone mass (50th percentile or lower) have an eightfold greater risk of new spine fractures compared with women above the 50th percentile of bone mass and no prevalent fractures. In addition to low bone mass, both prevalent spine fractures and prevalent non-spine fractures are strong risk factors for subsequent spine fracture. These data suggest that not all osteoporotic risk factors are expressed via bone mass, and that other, unmeasured risk factors, such as bone quality defects, may explain these results. In clinical terms, women with both prevalent fractures and low bone mass should be recognized as being at extremely high risk, and treatment potency should be commensurate with this level of risk.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2013
    Keywords: Nephron Filtration Rate ; Antidiuretic Hormone ; Diabetes Insipidus Rats ; Ferrocyanide Method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of antidiuretic hormone on the distribution of nephron filtration rates was studied in rats with hereditary diabetes insipidus using the Hanssen method for determination of nephron filtration rates as modified by de Rouffignacet al. [18]. Conversion of water diuresis to antidiuresis by infusion of ADH resulted in a moderate, but highly significant increase in the filtration rate of the juxtamedullary nephrons, while the nephrons of all other cortex regions filtered at an unaltered rate. A mechanism based on the action of ADH on distal nephron water permeability is proposed as an explanation: water inflow into the medulla very likely decreases when water diuresis is converted to antidiuresis. This occasions a rise in medullary osmolality which then causes an increase in the apparent viscosity of the blood flowing through the vasa recta. This is responsible for a rise in juxtamedullary postglomerular resistance which results in an increase in the effective filtration pressure and thus in the juxtamedullary nephron filtration rate. The results suggest that an increased juxtamedullary filtration rate participates in the establishment and maintenance of the inner medullary solute gradients, possibly as a consequence of an increased solute delivery to the ascending limbs of the long loops of Henle.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2013
    Keywords: Dog Kidney ; Saline Infusion ; Nephron Filtration Rate ; Filtrate Distribution ; Ferrocyanide Method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The intrarenal distribution of nephron filtration rate (N-GFR) was assessed using the Hanssen ferrocyanide technique in dogs which were chronically salt loaded with or without an additional acute sodium load and in sodium depleted dogs. In 4 dogs fed 7–10 days on a high sodium diet, superficial nephron filtration rate (SN-GFR) was 56.7±13.1 nl/min, middle nephron filtration rate (MN-GFR) was 65.2±14.3 nl/min, and the juxtamedullary nephron filtration rate (JN-GFR) was 82.4±17.1 nl/min, a value 52.3% higher than the SN-GFR. Creatinine clearance in these animals averaged 22.0±3.9 ml/min. In 4 animals which received an additional infusion of 0.9% NaCl at 4.0–4.5 ml/min for 2.5 h, the mean creatinine clearance rose from 16.6±2.0 ml/min to 20.3±0.7 ml/min and the distribution of N-GFR was: SN-GFR 70.5±21.2 nl/min, MN-GFR 83.6±23.8 nl/min and JN-GFR 91.2±24.3 nl/min. In this case, the JN-GFR was 29.3% higher than the SN-GFR. In one sodium depleted dog, (creatinine clearance 15.7 ml/min) the distribution of N-GFR was: SN-GFR 41.1±10.5 nl/min, MN-GFR 48.0±16.5 nl/min, and JN-GFR 58.0±19.0 nl/min, a value exceeding SN-GFR by 41.1%. These results imply that acute saline infusion in dogs induces a proportionately greater change in GFR of superficial than of juxtamedullary nephrons.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 344 (1973), S. 69-74 
    ISSN: 1432-2013
    Keywords: Nephron Filtration Rate ; Ferrocyanide Method ; Redistribution of GFR ; Urine Osmolarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were performed to clarify the cause of the dependency of juxtamedullary nephron filtration rate (JN-GFR) on the diuretic state of the animal. Using the ferrocyanide technique of de Rouffignacet. al. [5] the distribution of nephron filtration rates was determined during selective modification of final urine osmolarity by papillary superfusion with concentrated or isotonic solutions. Papillary superfusion with a 2000 mosmolar solution led to a mean urine osmolarity of 1848±78 mOsm/l. JN-GFR displayed a mean increase of 66.6% over the superficial nephron filtration rate (SN-GFR). When the superfusion fluid was isotonic urine osmolarity averaged 754±53 mOsm/l and JN-GFR increased by a mean of only 26.3% over the SN-GFR. Using the micropuncture technique it was shown that SN-GFR in a given animal was not altered when the superfusion fluid was interchanged. We conclude therefore that the change in the percentage increase in GFR from superficial to juxtamedullary nephrons is caused by a change of juxtamedullary nephron filtration rate. Since plasma ADH concentration was not altered this effect appears to be elicited by the changed medullary solute concentration rather than by a vasomotor action of the antidiuretic hormone.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 124 (1968), S. 79-82 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A total of 1125 normal chick embryos, representing 25 each of the 45 stages of Hamburger and Hamilton, were removed, fixed in Bouin's solution, stored in 70% ethanol and weighed with a semi-micro analytical balance. Entire blastoderms of stages 1-8 were weighed, whereas only embryos-proper were weighed in stages 9-45. As a consequence, results constituted two groups, each of which showed a geometric rate of growth marked only by minor deviations which were related to specific events of normal growth and development.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 161 (1968), S. 247-252 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Microcurie amounts of p32, Na22, Fe59, and Cl36 in normally occurring compounds were injected directly into the vitelline vessels of developing chick embryos at stage 24 (Hamburger and Hamilton, '51). The surviving embryos were sacrificed at stage 41. Hearts were removed and examined intact or sectioned for later examination. Coronary vessels were identified, classified according to size (large, diameter = 〉 80 μ; medium, diameter = 40-80 μ; small, diameter 〈 40 μ) and counted. There was a significant increase in the numbers of small and medium vessels which had developed in the presence of gamma radiation emitted by Na22- and Fe59-compounds. The p32- and Cl36-containing compounds did not affect the numbers of vessels of any size. The resulting increased vascularity is shown to be a matter of a distinct increase in numbers of blood vessels as opposed to a simple alteration of the normally occurring vessels.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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