Relationship between blood flow,bone structure,and239Pu deposition in the mouse skeleton

Summary The rate at which blood is supplied to several bones in female CBA mice was calculated from¹⁸F measurements in bone and blood. Blood flow measurements were compared with plutonium uptake in whole bone and on endosteal and periosteal bone surfaces. The results showed that: (a) the rate at which blood is supplied to bone determines the rate of deposition of plutonium; (b) there is a threshold rate of blood supply below which plutonium is not deposited; and (c) the rate of blood supply determines the density of plutonium deposition on endosteal but not on periosteal bone surfaces. These results are discussed in the light of the current bone blood supply hypotheses.     

Passive movement of radioactive microspheres from bone and soft tissue in an extremity

Bone biopsy is the definitive method for bone tumor diagnosis. Unfortunately, the procedure is not without risk and may substantially increase the rate and extent of tumor cell metastasis. This study used radioactive microspheres (15 micron diameter) to explore the spread of cell-sized particles from the distal femur into the lymphatic system, venous drainage, and local tissue following a simulated biopsy in the canine model procedure. In the initial group of test animals the microspheres rapidly moved from the femur through the venous system to the lungs. There was no movement from the femur into the lymphatic system within 4 days. The lungs effectively filtered the 15 micron microspheres, thus preventing arterial dissemination. Additional groups were used to explore the movement of the cell-sized particles from the soft tissue surrounding the bone. At the end of the 4 day experimental period, microspheres were found in the iliac lymph nodes in two of nine animals. Microspheres were not detected in the lungs of any of these nine animals. These results suggest that tumor cell-sized particles can move rapidly from the bone venous system to the lungs following a bone biopsy. It appears that the lymphatic system does not contribute to this rapid dissemination. However, the role of lymphatics in a more chronic process remains unclear.     

铜宫内节育器对大鼠子宫内膜毛细血管脆性通透性及内膜血流量的影响

对６３只置铜宫内节育器大鼠子宫毛细血管脆性、通透性和内膜血流量进行了分区测量。结果显示，１４例墨汁高压灌流标本的环压区内膜均有出血，出血率为１００％，与其它各区相比差异显著；千宫组织中伊文思蓝的含量环压区和邻环区明显高于其他各区。应用比受体阻断剂后，环压区与其他各区仍有显著差异；子官内膜的血流量以对压区作为１００％，对邻区、对远区、远环区和邻环区分别为１０９．４％、１１６．６％、１１８．９％和１０７．６％。环压区为８３．４％，显著低于以上各区。这表明铜宫内节育器可引起与其接触的内膜毛细血管脆性、通透性增加，血流量减少，可能是带器出血的重要原因。     

Bone loss and bone blood flow in paraplegic rats treated with calcitonin,diphosphonate, and indomethacin

Summary Sham-operated (SO) and paraplegic rats were treated from the day of operation during a period of 4 or 6 weeks with salmon calcitonin 4 IU/kg/day or a diphosphonate (APD) 1mM/kg/day or indomethacin 2.5 mg/kg/day. The consequence of spinal cord section on the femur and tibia is a loss of mineral which affects predominantly trabecular bone (−24 and −13% in calcium content for the tibial metaphysis and the whole bone, respectively, when compared with the SO controls), a twofold increase in bone blood flow as measured by the technique of the microspheres trapping, a moderate decrease of the 72 hour⁴⁵Ca accretion rate in the bone shaft, and an increase in the number of metaphyseal osteoclasts in the tibia. In paraplegics, all three drugs inhibit bone loss to some degree, calcitonin and indomethacin being mostly effective on the cortical bone of the shaft, and APD tremendously increasing the trabecular network of the metaphysis. APD is the only drug to exhibit a significant effect on the calcium content of the bones of the SO controls, but some effect is apparent for calcitonin on X-rays and histological preparations. The increase in bone blood flow in paraplegics is unaffected, this point being discussed in view of the hypothesis of the resorptive action of prostaglandins produced by newly formed vessels.⁴⁵Ca accretion rate increases in the shaft of calcitonintreated paraplegics, whereas it decreases in APD-treated controls and paraplegics. The number of osteoclasts decreases in paraplegics treated with calcitonin and indomethacin, and increases in both controls and paraplegics treated with APD. Thus, APD shows an outstanding effect on the bone loss at the very place where it occurs preferentially in the paraplegics (the trabecular metaphysis), but this and other effects affect the controls as well. Calcitonin and indomethacin act almost selectively on the diseased animals. All three drugs fail to inhibit the bone blood flow increase observed in paraplegics and supposedly associated with bone resorption.     

Effect of high dietary strontium levels on bone and egg shell calcium and strontium

The results of feeding high dietary levels of stable strontium to hens are reported. Dietary levels of strontium from 3,000 p.p.m. to 50,000 p.p.m. showed a significant increase in strontium content of the tibia bone and essentially no change in the calcium content. Plasma calcium concentration was shown to decrease with increasing dietary strontium treatment.Egg shell calcium showed a progressive decrease with increasing dietary strontium treatment, whereas the strontium content has a corresponding increase.X-ray diffraction analyses of bones and shells containing large amounts of strontium were unsuccessful in evaluating the from in which strontium was deposited.Research Career Development Awardee No. 5-K3-32,542 from the National Institute of Dental Research.     

The early effects of sympathectomy on bone blood flow

Summary Several laboratories, including our own, have investigated the physiology of bone blood flow by perfusion of the tibia via the nutrient artery. Any damage caused to the nerve supply by cannulation of the artery might affect the results. The possible effect of such damage was investigated by measuring blood flow to the dog tibia using a microsphere technique, before and after sympathectomy. No effect was found and the tibial nutrient artery is therefore a suitable vessel for perfusion when estimating nutrient exchange in bone.     

Heterogeneity of blood flow in tibial cortical bone: an experimental investigation using microspheres

The distribution of tibial blood flow was measured by injecting approximately (600-1000) x 10(3) 15 mu microspheres, labelled with either tin-113 (113Sn) or cobalt-57 (57Co) into femoral arteries of five mature greyhounds. The diaphyseal cortex, stripped of periosteum and devoid of marrow, was sawn into 40 pieces (10 transverse sections x 4 anatomical quarters/section). Relative deposition densities of the 113Sn microspheres in 40 pieces of cortex were found. These values, together with their associated masses, proved, from a statistical point of view, that flow rate heterogeneity was substantial in the diaphysis. In particular, for the diaphyseal cortex, distribution of relative deposition densities (flow rates) in six bones was found to be positively-skewed with a relative dispersion ((SD/mean) x 100) of approximately 40%.     

The effect of anaesthesia on the bone blood flow of the rabbit

The effect of anaesthesia on the rate of bone blood flow in the rabbit was studied. Two estimates of bone blood flow were performed, using 15 microns radioactively labelled microspheres, in three groups of rabbits. The first group was anaesthetised and the interval between the two estimates was 5 min. The second group was also anaesthetised but the interval between estimates was 60 min. The third group of rabbits was conscious and the interval between the two estimates was 4 h. In the first group, small uniform falls in whole bone blood flow were observed (mean change = -5%). In the second group, larger and less predictable reductions were observed (mean change = -24%). In the third group (conscious), little change was observed in whole bone blood flow during the 4-h experiment (mean change = +7%). It is concluded that substantial falls can occur in bone blood flow in the rabbit during a 1-h anaesthetic. If bone blood flow is to be monitored under anaesthesia, then the effect of the anaesthetic on bone blood flow must be accurately defined. In conscious rabbits, estimates of whole bone blood flow performed at an interval of 4 h under control conditions will give reproducible results.     

Distribution of fluoride concentration in the rat's bone

Summary The present study was undertaken to determine the fluoride distribution profile in the rat femur. Male Wistar rats were divided into four groups and given water containing 0, 25, 50, and 100 ppm of fluoride, respectively, for 10 weeks. The fluoride distribution from the periosteum to the endosteum was determined in each specimen after sampling using the abrasive microsampling technique [5]. In the outer circumferential lamellae, the concentration of fluoride was relatively high in the periosteal layer and then decreased gradually towards its interior. In the haversian and interstitial lamelae, it was lower and roughly constant through the tissue. In the inner circumferential lamellae, it rose again to reach the highest level towards the endosteal surface. Fluoride concentration throughout the cortex increased significantly with increasing intake of fluoride. These increases were especially marked at periosteal and endosteal surfaces.     

Rapid increase in fraction of cardiac output to bone in experimental calcium deficiency

The fractional redistribution of cardiac output to bone in dietary calcium deficiency was studied in the immature rat, utilizing the⁸⁶Rb method of Sapirstein. The results of the study indicated that there was a rapid and significant increase in the fraction of cardiac output to the femurs of the calcium-deficient rats relative to the control population. The increase in cardiac output fraction to bone occurred during the same general time period in which significant changes in the density, dry weight and ash content were detected. The increased fraction of the cardiac output to the femur in the calcium-deficient rats returned to normal after nine days, in spite of continuation of the calcium-deficient diet.From the Department of Radiology, Yale University School of Medicine. Supported by USPHS Grants AM-09664, GM-01152, AM-09429 and CA-06519.     

AnIn-Vitro analysis of two laser doppler flowmetry systems for evaluation of bone perfusion

Summary Laser Doppler Flowmetry (LDF) has been shown to be a useful tool in the experimental and clinical measurement of bone blood flow. Two LDF receiving fiber channel systems, one with a 2mW He−Ne tube laser source and the other with an infrared diode laser source, were compared with specific reference to their light attenuation through three types of bone as well as their threshold thickness for the same specimens. The threshold thickness was higher for the infrared diode system for all three bone types whereas the attenuation was identical. The demonstrated differences were most likely due to the criteria established for flow detection; the infrared diode system has a greater degree of amplification of the output signal, yielding a higher value at each thickness of bone. The two systems will produce similar output data when used for experimental analysis of bone blood flow.     

雷奈酸锶治疗老年男性骨质疏松性骨痛的疗效和安全性评价

【摘要】〓目的〓观察雷奈酸锶在男性骨质疏松症治疗中对骨痛的疗效,并评价其安全性。方法〓共纳入58例男性骨质疏松症患者,其中26例雷奈酸锶组,32例为钙剂组,分别测定两组患者治疗前后腰背部视觉疼痛模拟评分(VAS评分)、L1~L4椎体和Wards三角的骨密度值,并观察两组骨质疏松性骨折的发生率及服药后的不良反应。结果〓雷奈酸锶组患者治疗后6月及12月的VAS评分明显改善,低于钙剂组(P<0.001);雷奈酸锶组L1~L4椎体和Wards三角的骨密度值及T值在治疗后较治疗前上升显著,明显优于钙剂组(P<0.001)。雷奈酸锶组患者的主要不良反应为恶心及腹泻,钙剂组主要为便秘。结论〓雷奈酸锶能有效地提高骨质量和缓解骨痛,副反应少,是治疗男性骨质疏松性骨痛的良好选择。     

The effect of orchidectomy on bone metabolism in aging rats

Summary We have shown that orchidectomy in postpubertal 55-day-old rats led beyond 2 months to a decrease in bone growth and loss of weight. At 1 month postorchidectomy, we observed a threefold increase in bone blood flow, an increase in calcium accretion rate, and an increase in the number of osteoclasts in the metaphysis. In the present experimental study, orchidectomy was performed in 1-year-old rats when bone growth in length was no longer measurable. In the tibia and femur we observed a decrease in bone volume, a still more rapid decrease of bone calcium during the first postoperative month, a thinning of the cortical width, an initial increase in calcium accretion rate (+20% when compared to 31 days controls) followed by a decrease at 120 days (−22% and−11% when compared to controls for tibia and femur respectively), a 29% increase in bone blood flow, and an increase in the number of osteoclasts. We conclude that androgen deprivation in young and old animals leads to a modified bone architecture, independent of the androgen impact on bone growth.     

Comparison of two laser Doppler flowmetry systems for bone blood flow analysis

Summary The development of laser Doppler flowmetry (LDF) has provided a real-time, reliable method for monitoring capillary perfusion in multiple tissues. LDF has potential for the experimental and clinical assessment of bone blood flow. To compare the accuracy and ease of use of two commercially available laser Doppler flowmeters with different mechanisms for processing the Doppler-shifted component of light, estimates of bone blood flow were obtained in a sheep model using the two systems, and the values derived then compared with estimates of bone blood flow also obtained in a sheep using the technique of injection of labeled microspheres. The single-channel laser Doppler flowmeter, the LD 5000, processes the reference and Doppler-shifted beams on the surface of a single photodetector using optical heterodyning for measurement. The dual-channel flowmeter, the Periflux 2, uses two optical fibers to transmit reference and Doppler-shifted light to two separate photodetectors. The differential amplification and detection system improves the signal-to-noise ratio. Measurement of both metaphyseal (cancellous) and diaphyseal (cortical) blood flow using both LDF systems was compared with values obtained with an injection of⁸⁵Sr-labeled microspheres in three sheep. The LDF measurements were repeated after occlusion of the left femoral artery, and a⁴⁶Sc microsphere injection was performed prior to animal sacrifice. Two of the animals developed vasomotor instability, resulting in poor correlation between the measurements obtained with the Periflux 2, which is motion sensitive, and the values obtained with the microsphere method. High correlation was apparent in two of the three animals for the LD 5000 and the microsphere values. Four additional sheep were evaluated using only the Periflux 2, and the data collected yielded R values of 0.6–0.98. Both the single- and dual-channel LDF systems offer accurate assessment of local cortical and cancellous bone blood flow.     

Limitations of radioactive microspheres as tracers for bone blood flow and extraction ratio studies

Summary Radioactive microspheres have been used for measuring bone blood flow and the extraction ratios of bone-seeking radionuclides, but we have shown that the technique is not completely valid. Bone uptake of¹⁸F and⁸⁵Sr was compared with that of microspheres simultaneously injected into the heart or aorta of rats and rabbits under a variety of conditions. In single-passage experiments with quick killing to avoid recirculation, attention was focused on the tibiae and femora which could be dissected quickly to avoid post-mortem migration. For the rest of the skeleton, the effect of the latter was minimized by allowing recirculation for 5 min and comparing blood flow determinations in conjunction with a cardiac output measurement. The apparent extraction ratio of¹⁸F was variable and always exceeded unity in the single-passage experiments. With recirculation, there were significant differences between the extraction ratios for some bones, and the ratios sometimes exceeded unity. Extraction ratios for⁸⁵Sr were similarly variable, but lower. When⁸⁵Sr was compared directly with¹⁸F, the relative extraction ratio was 0.8, with little variation between bones or animals. It is concluded that the flux of microspheres entering the vasculature of bone is not representative of blood flow, owing to the removal of some microspheres in pre-osseous capillary beds. Microspheres are therefore not a satisfactory standard for the determination of extraction ratios.     

The cycling concept of exchange in bone

An hypothesis has been developed to explain in a semi-quantitative fashion the wide variations in time required for the equilibration in the skeleton of various radioactive substances when they are introduced into the circulation. The basis for the hypothesis rests on the assumption that three variables define the rate-limiting step in bone exchange: a) the rate of perfusion of bone, b) the concentration of the ion plasma, and c) the concentration of the ion in bone. Using this idea and data from the literature, cycling times were calculated for Cl^–, Na⁺, K⁺, and Ca⁺⁺. They were found to vary by four orders of magnitude (from 10 min for Cl^– to 64 days for Ca⁺⁺ in the rat).These predictions were tested for²²Na- and⁴⁵Ca-exchange in a column of apatite mineralin vitro. In vivo ³⁶Cl- and⁴²K-exchange in rat femur was studied. The blood disappearance of²²Na in man was also examined. Finally, data in the literture of⁴⁵Ca-exchange in the rat molar was redrawn. In every case, experimental results closely approximated the predictions of the cycling concept.Some of the implications of these findings are briefly discussed.

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Zusammenfassung Es wurde eine Hypothese aufgestellt, um auf semi-quantitative Weise die breite Variabilität der Zeit zu erklären, die benötigt wird, um im Skelett ein Gleichgewicht von verschiedenen radioaktiven in den Kreislauf eingeführten Substanzen herzustellen.Diese Hypothese beruht auf der Annahme, daß der geschwindigkeitsbeschränkende Faktor beim Knochenaustausch durch 3 Variablen definiert ist: a) das Maß der Knochenperfusion, b) die Konzentration der Ionen im Plasma und c) die Konzentration der Ionen im Knochen. Auf Grund dieser Annahme und gestützt auf Angaben aus der Literatur wurden die cycling times für Cl^–, Na⁺, K⁺ und Ca⁺⁺ berechnet. Diese variieren in 4 Größenordnungen, beispielsweise von 10 min für Cl^– bis zu 64 Tagen für Ca⁺⁺ bei der Ratte.Diese Annahmen wurden für den Austauschin vitro von²²Na und⁴⁵Ca in Apatitmineral in einer Säule geprüft. Der Austausch von³⁶Cl und von⁴²K wurdein vivo am Rattenfemur studiert. Die Abnahme von²²Na im menschlichen Blut wurde ebenfalls verfolgt. Schließlich wurden Literaturangaben über den Austausch von⁴⁵Ca in Rattenbackenzähnen überprüft. Die Versuchsresultate kamen dabei sehr nahe an die auf Grund des cycling concept erwarteten.Einige der Zusammenhänge dieser Befunde werden kurz besprochen.

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Résumé Une hypothèse, destinée à rendre compte de façon semi-quantitative, des grandes variations de temps nécessaire à équilibrer, au niveau du squelette, divers produits radioactifs, introduits dans le torrent circulatoire, est mise au point. Cette hypothèse est basée sur le fait que 3 facteurs interviennent dans les échanges osseux: a) la vitesse de perfusion de l'os, b) la concentration ionique du plasma, et c) la concentration ionique de l'os. Partant de cette hypothèse et de résultats publiés dans la littérature, des temps de cyclage sont calculés par Cl^–, Na⁺, K⁺ et Ca⁺⁺. Ils varient selon quatre ordres de grandeur (de 10 min pour Cl^– à 64 jours Ca⁺⁺, chez le rat).Ces résultats ont été vérifiés pour des échanges de²²Na et de⁴⁵Ca dans une colonne d'apatite minéralin vitro. Des échanges de³⁶Cl et de⁴²K ont été étudiésin vivo au niveau du fémur de rat. La disparition sanguine du²²Na a été suivie chez l'Homme. Enfin des résultats d'échanges de⁴⁵Ca, au niveau de molaires de rat, publiés dans la littérature, ont été recalculés. Dans chaque cas, les résultats expérimentaux ont confirmé les prédictions de l'hypothèse du cyclage.

     

Changes in bone marrow blood flow with aging

We investigated changes in bone marrow blood flow and histology with aging in rabbits. Bone marrow blood flow was measured by the hydrogen washout method, which was performed in the proximal tibia of Japanese white rabbits, 3-42 months of age. Bone marrow blood flow was found to decrease with age. Histological observations of the proximal tibia identified a decrease in the number of osteoblasts and hematopoietic cells, an increase of the number of empty lacunae, a reduction in bone formation rate, and a degeneration of marrow fat with aging. These results suggest that the decrease of bone marrow blood flow is related to histological changes found with aging.     

Fluoride-induced bone changes in lambs during and after exposure to sodium fluoride

The evolution of bone changes induced by fluoride after the end of exposure was investigated in lambs. Sodium fluoride (NaF) was given orally at a dose of 3.5 mg/kg per day to 14 animals for 120 days. A group of 7 control and 7 treated lambs was slaughtered at the end of NaF administration (T120) and another group 120 days after the end of NaF exposure (T240). At T120, the bone fluoride content (BFC) was very significantly increased in treated animals. The histomorphometric analysis confirmed that fluoride induces an increase in bone formation (the osteoid perimeter and area were 3-fold and 4.5-fold higher respectively in treated than in control animals). The number of osteoblasts was significantly augmented. Serum osteocalcin level was twice as high in treated animals compared with controls. The bone formation rate at the tissue level (BFR) doubled after treatment, but the apposition rate (Aj.AR) was half that in the control group. The mineralization lag time (Mlt) was 120 days in treated animals compared with 42 days in controls. At T240, BFC had decreased by 50% compared with the level at T120, but it was still significantly higher than in controls. The osteoid and osteoblastic parameters were 2 and 1.3 times higher than in control animals. BFR remained significantly increased in treated animals, but Aj.AR and Mlt were similar in control and treated animals. In conclusion, after 4 months of NaF exposure fluoride induced an increase in osteoblast natality and bone formation at the tissue level, associated with a toxic effect at the individual cell level. Four months after the end of NaF exposure, positive effects on bone formation were still present but the evidence of cellular toxicity had disappeared.     

Cortical bone microperfusion: response to ischemia and changes in major arterial blood flow.

In order to investigate the effects of short-term ischemia on cortical bone microperfusion, an isolated porcine tibia diaphyseal preparation based on intact nutrient vessels was developed. Laser Doppler flowmetry (LDF) was utilized to assess continuously the cortical microcirculation and the response to short-term ischemia. The femoral artery was isolated and clamped to develop the condition of bone ischemia. On release of the clamp, reactive hyperemia was documented in all animals. Using a roller pump connected to a segment of femoral artery, the same preparation was utilized to investigate the effect of a changing femoral artery flow on the cortical microcirculation. A positive correlation between LDF output and change in arterial inflow (r = 0.64) was defined. This model has the potential for studying the effect of ischemia on bone cell viability.     

The divalent strontium salt S12911 enhances bone cell replication and bone formation in vitro

In this study, we have determined the effect of the divalent strontium salt S12911 on bone cell replication and bone formation in two culture systems. In the first series of experiments, half-calvariae of newborn rats were cultured with S12911 from 24 to 96 h and labeled with ³H-thymidine for the last 6 h of culture or treated with S12911 for 24 h and labeled for 24 h with ³H-proline 24–48 h after the removal of the agent. Calvariae were then processed for histomorphometry. S12911 at 10⁻³ M increased the replication of preosteoblastic cells by 30–50% after 24 h and by 60% after 96 h of treatment. This effect was specific, since the number of labeled osteoblasts and of periosteal cells was not changed. A transient 24 h treatment with S12911 at 10⁻³ M increased bone formation 24 and 48 h after the removal of the agent. ^3H-proline labeled surfaces and bone formation rates were increased by 20%–35%. In the second series of experiments, sequential collagenase digestions were used to isolate cell populations enriched in fibroblasts or osteoblasts (Ob) from 22 day fetal rat calvariae. Treatment with S12911 at 10⁻³ M for 24 h enhanced DNA synthesis by three- to fourfold in cell populations enriched in fibroblasts and preosteoblastic cells. The effect was less pronounced and inconsistent in Ob cells. S12911 at 10⁻³ M for 24 h also increased collagen and non-collagen protein synthesis by 35% in Ob cells. These data indicate that the divalent strontium salt S12911 enhances bone cell replication and bone formation in vitro, an effect that may contribute to the previously reported effects of S12911 on trabecular bone mass in vivo.