Estrogen and cancellous bone loss in the fowl

Long-term follow-up study with positron emission tomography (PET) has been conducted in a patient with superficial siderosis for ten years. A 63-year-old right-handed woman began to exhibit a cerebellar ataxia when she was 52 years old. Thereafter she has been exhibiting a slowly progressive course of pyramidal signs, hearing loss, anosmia, bilateral sciatica and memory disturbance in addition to the cerebellar ataxia. Series of x-ray CT and MRI disclosed a progressive atrophy of the cerebellum, specifically in the superior vermis, and a mild diffuse atrophy in the cerebral hemispheres, whereas no significant atrophy was seen in the brainstem. A marked hypointensity was seen along the rim of the brain structures including brainstem, cerebellum, sylvian fissures and the medial temporal lobes on MR T 2-weighted images. This hypointensity was also found at the edges of the third and fourth ventricles. These findings were regarded as haemosiderin deposit. By using oxygen-15, PET was carried out repeatedly with ten-year interval. In the initial PET study, both cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were mildly decreased in the cerebellar hemispheres and the occipital cortices. The follow-up PET study revealed a progressive reduction of CMRO2 in the brainstem, cerebellar hemispheres and temporal cortices including the hippocampus in which the haemosiderin deposition was marked on MRI, whereas the reduction of CBF was not advanced as compared with CMRO2. It was suggested that the progressive reduction of CMRO2 in the brain sites where the haemosiderin deposition was observed on MRI reflected the clinical course of neurological deterioration.     

Connectivity and the elastic properties of cancellous bone

The effect of ibuprofen enantiomers on the stereoselective binding of 3-acyloxy-1,4-benzodiazepines to human serum albumin (HSA) was studied using both native and Sepharose-immobilized protein. (S)-Lorazepam acetate exhibited considerably enhanced binding, especially in the presence of (+)-(S)-ibuprofen. The phenomenon is an indication of cooperative allosteric interaction between different binding sites during multiple cobinding of two ligands.     

Impaction of cancellous bone grafts impairs osteoconduction in titanium chambers

The method of using morselized compacted cancellous allografts for hip arthroplasty revision shows results that seem to differ dramatically from other kinds of allografting. In structural cancellous allografts, bone ingrowth usually is limited to 2 to 3 mm, whereas morselized compacted grafts seem to be remodeled totally in several cases, as judged by radiography. In the current study, impacted cancellous allografts were compared with unimpacted allografts. Seventeen rats had a bone conduction chamber implanted in the tibias bilaterally. On one side the chambers contained an impacted graft (bone volume fraction 65%) and on the contralateral side an unimpacted graft (bone volume fraction 35%). Impaction of the grafts was done preoperatively with a pressure of either 25 or 2500 MPa. Ingrowing bone could enter the cylindrical interior of the chamber only at one end. After 6 weeks the mean distance the ingrown bone had reached into the graft was measured on histologic slides. With both impaction pressures, the bone ingrowth distance was decreased to 30% of the unimpacted controls. It appears that impaction alone does not have a favorable effect on the osteoconductive properties of a bone graft. On the contrary, impaction seems to disfavor osteoconduction. However, in the clinical situation this is not necessarily a disadvantage.     

Pullout strengths of cannulated and noncannulated cancellous bone screws

The pullout strengths of large diameter cannulated and noncannulated cancellous screws were tested in a synthetic polyurethane foam. The foam was fabricated to have mechanical properties equivalent to human cancellous bone and was characterized by compression testing before screw pullout. Long and short thread commercially available screws from four manufacturers were tested. In screws with short threads (16-22 mm), there was no difference in holding power among the four cannulated screw designs. However, the short thread noncannulated screw performed significantly better than the short thread cannulated screw with the lowest pullout strength. There were statistically significant differences in holding power among the different long thread (32-40 mm) cannulated screw designs. Additionally, the long thread noncannulated screw had better holding power than several of the long thread cannulated screws. No differences in pullout strengths between comparably sized cannulated and noncannulated screws produced by the same manufacturer were found, and all long thread screws had significantly greater holding power than all short thread screws. There was no demonstrable effect on holding power when screws were inserted with or without tapping. Thread surface area was found to be a reasonable predictor of holding power.     

Mandibular reconstruction with cancellous bone, hydroxylapatite and titanium mesh

Over the past 20 years, titanium mesh combined with autologous iliac crest spongiosa and hydroxylapatite has performed well in the restoration of mandibular discontinuity defects in 79 patients. In 14 irradiated patients with a transplant bed of inferior quality, however, complications and failures occurred more often than in the 65 non irradiated patients. The results of our investigation clearly show that the success of mandibular reconstruction mainly depends on a well vascularized transplant bed.     

Deep-frozen allogeneic cancellous bone grafts in 10 dogs: a case series

Deep-frozen, aseptically collected and processed allogeneic cancellous bone was implanted in eight dogs during the surgical repair of diaphyseal long bone fractures and in two dogs during arthrodeses. A combined allogeneic and autogeneic cancellous bone graft was used in two fractures with a segmental bone loss of more than 5 cm. Bone union occurred in five fractures and in both arthrodeses. Failure of fixation occurred in two dogs with nonunion fractures and in a third dog with an open, infected fracture. Biopsies from the fracture sites were obtained from these dogs following failure of their fracture fixation. The cancellous bone graft appeared to be in the process of normal incorporation in each case. Failure of fixation was attributed to technical or case management errors or both, in each of the three fractures that failed to achieve bony union. Frozen allogeneic cancellous bone grafts were effectively incorporated when used in the primary repair of fractures and arthrodeses. Combined autogenous and allogeneic cancellous bone grafts may be particularly useful in the repair of fractures with large segmental diaphyseal bone defects. The use of allogeneic cancellous bone grafts in nonunion fractures requires further investigation before it can be recommended.     

One-stage open cancellous bone grafting of infected fracture and nonunion

BACKGROUND: A quantitative study of dermal and arterial elastic fibers as a function of age was carried out by computerized image analysis. OBJECTIVE: We investigated whether any parallelism can be established between the morphometric parameters of elastic fibers from the skin and the temporal artery in elderly subjects. METHODS: we quantitated the skin elastic fibers of the reticular dermis and the elastic fibers of the temporal artery using a specific staining procedure followed by automated image analysis in 16 subjects of age range 63-87 years. RESULTS: There was a good correlation between the area fraction occupied by the elastic fibers in the unexposed skin (inner part of the upper arm) and aging (r = 0.669, p < 0.01). The area fraction occupied by elastic fibers in unexposed skin was correlated with the area fraction occupied by elastic fibers in the deep part of the temporal artery (r = 0.498, p < 0.05). Actinic elastosis affected both tissues, but there was no correlation between the amount of elastotic material in the exposed skin and the area fraction of elastic fibers in the superficial part of the temporal artery. CONCLUSION: We provided evidence that in sun-protected tissues the area fraction occupied by elastic fibers in dermis and deep part of the temporal artery showed a significant correlation. We proposed that skin biopsies were a valuable diagnostic tool for predicting arterial wall abnormalities of elastic fibers.     

Autologous fibrin adhesive in mandibular reconstruction with particulate cancellous bone and marrow

Displacement of bone graft particles during their placement, neck flap closure, and insertion of the freeze-dried mandibular crib housing the graft to the glenoid fossa is a commonly encountered problem during major mandibular reconstruction with autogenous particulate cancellous bone and marrow. Autologous fibrin adhesive proved to be a solution as demonstrated in a series of 33 cases. In addition to adhesive and hemostatic properties, it helped the remodeling process begin about 50% earlier by providing the substratum for migration of mesenchymal cells, accelerating revascularization and migration of fibroblasts, stimulating the growth of both fibroblasts and osteoblasts, and slowing the multiplication of microorganisms. Bony incorporation and remodeling were detected radiographically at the fourth postoperative week compared with the eighth week in bone grafts without autologous fibrin adhesive.     

The Streamtest cup: a new uroflow device

OBJECTIVES: To create an inexpensive, simple, accurate, and noninvasive device to evaluate the character of a male's urinary stream. METHODS: The results of a formal in-office uroflow study performed on 50 symptomatic men were compared with those of the same men using the Streamtest cup. RESULTS: All men with a urine flow of 12 mL/s or greater reached or exceeded the red line on the Streamtest cup. No patient whose stream was less than 11 mL/s was able to reach the red line. CONCLUSIONS: Uroflowmetry is an excellent study in diagnosing, managing, and monitoring the treatment of urinary obstructive disease secondary to benign prostatic hyperplasia. The Streamtest cup can provide both the patient and the physician with a clinically accurate visual assessment of an individual's urine flow at a significant cost savings over other testing means. The Streamtest cup when compared with a formal in-office uroflow study provided clinically similar results in separating obstructive uropathy from a normal urinary flow.     

Effect of resistance exercise training on cortical and cancellous bone in mature male rats

The thermal inactivation kinetics of Salmonella enteritidis PT4 between 49 and 60 degrees C were investigated. Using procedures designed to eliminate methodological artifacts, we found that the death kinetics deviated from the accepted model of first-order inactivation. When we used high-density stationary-phase populations and sensitive enumeration, the survivor curves at 60 degrees C were reproducibly biphasic. The decimal reduction time at 60 degrees C (D60 degrees C) of the tail subpopulation was more than four times that of the majority population. This difference decreased with decreasing temperature; i.e., the survivor curves became more linear, but the proportion of tail cells remained a constant proportion of the initial population, about 1 in 10(4) to 10(5). Z plots (log D versus temperature) for the two populations showed that the D values coincided at 51 degrees C, indicating that the survivor curves should be linear at this temperature, and this was confirmed experimentally. Investigations into the nature of the tails ruled out genotypic differences between the populations and protection due to leakage from early heat casualties. Heating of cells at 59 degrees C in the presence of 5 or 100 micrograms of chloramphenicol per ml resulted in reductions in the levels of tailing. These reductions were greatest at the higher chloramphenicol concentration. Our results indicate that de novo protein synthesis of heat shock proteins is responsible for the observed tailing. Chemostat-cultured cells heated at 60 degrees C also produced biphasic survivor curves in all but one instance. Cells with higher growth rates were more heat sensitive, but tailing was comparable with batch cultures. Starved cells (no dilution input) displayed linear inactivation kinetics, suggesting that during starvation a rapid heat shock response cannot be initiated.     

Management of small infected tibial defects with antibiotic-impregnated autogenic cancellous bone grafting

Between January of 1991 and December of 1993, 36 patients who had tibia fractures complicated by small infected tibia defects were treated at the authors' service. The group included 30 men and 6 women whose average age was 36.5 years (range, 18-72 years). The average follow-up period was 3.7 years. By using the Cierney-Mader staging classification of chronic osteomyelitis, 26 of 36 patients (72%) were stage 4A and 10 of 36 patients (28%) were stage 4B. Ten patients required muscle transfer. All patients were treated with a two-stage protocol. In the first stage, antibiotic-impregnated polymethylmethacrylate bead chains were used to obliterate the debrided osseous defect. In the second stage, the beads were removed, and the defects were reconstructed with antibiotic-impregnated autogenic cancellous bone graft. The time between the first and second stage was 2 to 8 weeks for patients without muscle transfer and 8 to 12 weeks for the patients with muscle transfer. The bone defects ranged from 2 to 4 cm. Wound healing and bony union were achieved in all patients. Only two patients had recurrent infections. The infection arrest rate was 94.4%. Minor pin tract infection of the external skeletal fixation was seen in two patients. Two patients developed skin rashes secondary to antibiotic therapy. Radiographs at an average follow-up of 3.7 years showed good consolidation and hypertrophy of grafted bones in all patients. After 3 to 5 years of follow-up, our results suggest that the use of impregnating antibiotics have no adverse effects on autogenic cancellous bone graft incorporation and may help to eliminate infection. This treatment protocol provided rapid recovery from osteomyelitis. The use of antibiotic-impregnated autogenic bone graft seems to be an effective and safe method for the management of small infected tibial defects.     

The effects of risedronate on canine cancellous bone remodeling: three-dimensional kinetic reconstruction of the remodeling site

To investigate the dose-dependent effects of risedronate on cancellous bone remodeling, adult female beagle dogs were treated with either placebo, 0.1, 0.5, or 2.5 mg/kg/day of risedronate orally in an intermittent cyclic regimen (7 days on 21 days off), repeated three times. Iliac cancellous bone samples were subjected to histomorphometric analysis and three-dimensional (3-D) kinetic reconstruction of the remodeling site was performed. In the 0.1 mg/kg dose group, resorption and activation indices were no different from the placebo group. However, wall thickness was increased resulting in a positive bone balance at the level of the remodeling unit. In the 0.5 and 2.5 mg/kg dose groups, a dose-dependent reduction in activation frequency and tissue level bone formation was observed. Resorption rates were also significantly decreased, 60% and 80% for the 0.5- and 2.5-mg/kg groups, respectively. An approximate 25% reduction in final erosion depth was noted in both these groups. Analyses of the growth curves of the bone packet confirmed that the kinetics of the growth of a completed packet were different in the 0.5- and 2.5-mg/kg dose groups compared with placebo. These changes were associated with a significant increase in the final wall thickness in both groups indicating no net impairment of osteoblast function. These increases in wall thickness in combination with the reductions in final erosion depth in the 0.5 and 2.5 mg/kg groups resulted in a significant dose-dependent positive bone balance. This pharmacological profile suggests that risedronate may be of therapeutic utility in the treatment of metabolic bone diseases where reductions in activation frequency and resorptive cell activity at the level of the remodeling unit are a therapeutic goal.     

Early induction of alterations in cancellous and cortical bone histology after orchiectomy in mature rats

Androgen deficiency is associated with low bone mass in humans and animals, but the remodeling alterations that lead to bone loss are unclear. Our objective was to define early responses in both cancellous and cortical bone to orchiectomy (ORX) using histomorphometry in sexually mature (4-month-old) rats. A total of 62 male rats, 4 months of age, were divided into six groups, sham operated (SH) or orchiectomized (ORX), and sacrificed 1, 2, or 4 weeks after ORX. Calcein was given 5 and 2 days before sacrifice to label mineralizing surfaces. Bone mineral density (BMD) was measured in excised femurs by dual energy X-ray absorptiometry (DEXA). Static and dynamic histomorphometry was evaluated in the cancellous bone of the proximal tibial metaphysis and lumbar vertebral bodies, and in the cortical bone of the tibial diaphysis. Osteopenia began to develop by 2 weeks after ORX, though weight gain and femur length did not change. Femoral BMD was significantly reduced and BMC decreased (NS) by 4 weeks after ORX (p < 0.05). Tibial and vertebral cancellous bone volume decreased 19% and 13%, respectively, while osteoblast and osteoclast surfaces, and numbers of osteoclasts, increased after ORX. At 2 weeks post-ORX, an increase in cancellous bone formation rate was attributable primarily to an increase in mineralizing surfaces and a smaller rise in mineral apposition rate. In contrast, cortical bone periosteal, but not endosteal, bone formation rate and mineralizing surfaces decreased. We conclude that ORX stimulates cancellous and diminishes periosteal bone turnover rapidly after ORX, with subsequent decreases in bone volume and mineral density. The clear divergence in cortical and cancellous bone responses to hypogonadism raises important questions regarding the control of bone formation and its role in defining the skeletal phenotype.     

Age-related changes in the compressive strength of cancellous bone. The relative importance of changes in density and trabecular architecture

Ectopic atrial tachycardia (EAT) is a rare but reversible cause of dilated cardiomyopathy (DCMP). The diagnosis and the definite control of the arrhythmia are essential for the regression of DCMP. Unfortunately, conventional antiarrhythmic drugs usually fail to control the arrhythmia, and the results of surgery or direct current ablation are suboptimal. Recently, radiofrequency (RF) catheter ablation has been evolving as a safe and effective therapy for EAT. This report describes the RF ablation treatment of a 14-year-old boy with DCMP secondary to chronic EAT. Activation mapping was used for the purpose of identifying the focus origin located just anterior to the coronary sinus os. RF energy applied at this focus successfully terminated the tachycardia. No complications related to the procedure were observed. RF ablation not only caused elimination of the EAT but also led to improvement in left ventricular function as early as two weeks after the procedure, and complete resolution of DCMP in three months.     

中国第一座短流程薄板厂

本文介绍在中国建成的第一座短流程薄板厂并进行讨论。     

The glottic aperture seal airway: a new ventilatory device

BACKGROUND: None of the presently used airway devices are ideal regarding ease of insertion, alignment with the laryngeal inlet, and provision of a high-pressure seal from the environment. The purpose of this study was to determine, in awake volunteers, the performance of a new ventilatory device, the glottic aperture seal airway, regarding ease of insertion, alignment with the laryngeal inlet, and forced exhalation seal pressure (PFES). METHODS: The glottic aperture seal airway consists of a curved tubular component that ends in the middle of an elliptical foam cushion glottic component. The posterior surface of the foam has a curved flexible plastic backing, which imparts a 60 degree angle between the proximal half and the distal half of the foam cushion. When the glottic aperture seal airway is properly in situ in a supine patient, the proximal half of the foam cushion is opposite the laryngeal inlet. The posterior surface of the plastic backing has a balloon attached to it. Inflation of the balloon presses the ventilation hole and foam cushion up against the laryngeal inlet, thereby creating a seal from the environment. Using the laryngeal mask airway as a control device, the glottic aperture seal airway was tested for time and ease of insertion, fiberoptic alignment with the laryngeal inlet, and PFES in 18 lightly sedated and locally anesthetized volunteers. RESULTS: The glottic aperture seal and laryngeal mask airways were inserted with equal ease and speed. The fiberoptic alignment with the larynx was excellent for both the glottic aperture seal and laryngeal mask airways. In all volunteers, the mean +/- SD PFES values at 0-, 10-, 20-, 30-, and 40-ml balloon inflation volumes of the glottic aperture seal airway were 23.4 +/- 11.8, 29.6 +/- 12.4, 42.7 +/- 12.5, 56.9 +/- 5.6, and 60 +/- 0 cm H2O, respectively; the PFES at > or = 20 ml balloon inflation volume of the glottic aperture seal airway was significantly greater than with the laryngeal mask airway (19.4 +/- 6.7 cm H2O, P < 0.01). A PFES of > or =60 cm H2O was achieved with the glottic aperture seal airway in all volunteers (n = 2 at 10 ml, n = 3 at 20 ml, n = 9 at 30 ml, and n = 4 at 40 ml). The glottic aperture seal airway did not cause any trauma. CONCLUSION: In awake volunteers, the glottic aperture seal and laryngeal mask airways were equally easy to insert and position. The glottic aperture seal airway was capable of achieving a higher PFES than the laryngeal mask airway.     

Histological integration of allogeneic cancellous bone tissue treated by supercritical CO2 implanted in sheep bones

Different chemical or physical methods of bone processing have been developed to decrease the antigenicity of allogeneic bone which may delay or prevent graft integration. We have developed a method based on delipidation and deproteination of the bone with a supercritical fluid and hydrogen peroxide. Cylinders of cancellous allogeneic bone treated in this way were implanted for four weeks, four months or eight months in holes drilled in sheep condyles or tibial plateau. Histological sections were then processed and analysed qualitatively and quantitatively using an image analysis software coupled to a light microscope. Measurements were made of the trabecular bone surface (BS/TS), the relative osteoid surface (OS/BS), the active osteoid surface (OS/BS), active resorption surface (Oc.S/BS) and the relative surface of newly formed bone. After four weeks, the control cylinders (non-treated allogeneic bone) had been invaded by cellular tissue composed of lymphocytes and plasmocytes surrounding remnants of the donor bone marrow tissue. The processed cylinders showed osteoid apposition at the surface of their external trabeculae. The trabecular bone and osteoid surfaces were significantly higher in the processed bone sections than in the control bone sections. After four months, most of the control material had been osteolysed and replaced by connective tissue containing lymphocyte islets, while the processed materials showed a large amount of bone synthesized at the surface of implant trabeculae which appeared fragmented and disseminated within the newly formed bone. All the histomorphometric parameters measured were significantly different from those of the control. By eight months, most of the control material had been totally osteolysed with very little bone ingrown in the implantation site. Only one control implant had been integrated. The processed cylinders were difficult to discern from the bone in which they were implanted. The parameters measured on the processed cylinders were significantly higher than those measured on the control sections. IN CONCLUSION: the treatment applied to the bone enhanced allogeneic bone integration and could provide a new kind of tissue treatment for bone banking.