Increased HTLV-I proviral load and preferential expansion of HTLV-I Tax-specific CD8+ T cells in cerebrospinal fluid from patients with HAM/TSP

To date, high human T-cell lymphotropic virus type I proviral load in patients with human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis has been reported and is thought to be related to the pathogenesis of human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis. However, the proviral load in cerebrospinal fluid has not been well investigated. We measured human T-cell lymphotropic virus type I proviral load in cerebrospinal fluid cells from human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis patients using real-time quantitative polymerase chain reaction (TaqMan). Human T-cell lymphotropic virus type I proviral load in cerebrospinal fluid cells were significantly higher than that of the matched peripheral blood mononuclear cells, and a high ratio of human T-cell lymphotropic virus type I proviral load in cerebrospinal fluid cells to peripheral blood mononuclear cells were observed in patients with short duration of illness. Human T-cell lymphotropic virus type I Tax-specific CD8+ T cells, as detected by peptide-loaded HLA tetramers, accumulated in cerebrospinal fluid compared with that in peripheral blood mononuclear cells, while the frequency of cytomegalovirus-specific CD8+ T cells in cerebrospinal fluid was reduced. These observations suggest that accumulation of both human T-cell lymphotropic virus type I-infected cells and preferential expansion of human T-cell lymphotropic virus type I-specific CD8+ cells in cerebrospinal fluid may play a role in the pathogenesis of human T-cell lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis.

Total synthesis of capsanthin using lewis acid-promoted regio- and stereoselective rearrangement of tetrasubstituted epoxide

The synthesis of capsanthin 1 was accomplished via the C15-cyclopentyl ketone 13 prepared by Lewis acid-promoted regio- and stereoselective rearrangement of the epoxide 12.

Urinary 1-hydroxypyrene in coke oven workers relative to exposure, alcohol consumption, and metabolic enzymes

OBJECTIVES

To investigate the influence of personal lifestyle--such as smoking and alcohol consumption-on urinary 1-hydroxypyrene (1-OHP) concentrations in coke oven workers exposed to polycyclic aromatic hydrocarbons (PAHs) and to evaluate the association of 1-OHP concentrations with the genetic polymorphism of several metabolic enzymes including cytochrome P-450 (CYP) 1A1 and glutathione S-tranferases (GSTs).

METHODS

The study population contained 162 coke oven workers and 58 controls employed at the largest iron and steel factory in China. Personal data were collected at the interview. 1-OHP in urine was measured with high performance liquid chromatography with fluorescence detection. Genetic polymorphisms were identified by the polymerase chain reaction (PCR) method.

RESULTS

A positive association between excretion of urinary 1-OHP and the levels of exposure to PAHs was confirmed. Those people who consumed >or=50 g/day ethanol had significantly higher 1-OHP excretion than did other coke oven workers (p<0.01). No significant difference in urinary 1-OHP was found between smokers and non-smokers, in both controls and exposed subjects. The variant homozygotes at exon 7 of the CYP1A1 gene had significantly higher urinary 1-OHP concentrations than other CYP1A1 genotypes among the exposed workers (p=0.03). There was less association between the concentrations of 1-OHP and the GSTM1, GSTP1, or GSTT1 polymorphism.

CONCLUSIONS

The present study confirmed that urinary 1-OHP is a good biomarker for exposure to PAHs. Alcohol consumption affected urinary 1-OHP excretion. The variant genotypes of the CYP1A1 gene may result in the enhancement of PAH metabolites. It is helpful to understand the role of individual susceptibility on metabolism of carcinogens. These findings suggest that the modulating effect of individual lifestyle factors or genetic nature should be considered in future studies on occupational exposure to PAHs and in evaluating the health risk from harmful chemicals.

Intradural arachnoid cyst associated with thoracic spinal compression fracture: 7-year follow up after surgery

STUDY DESIGN

A case report with long-term follow after a surgical procedure.

OBJECTIVES

To describe a case of intradural arachnoid cyst secondary to a compression fracture in the thoracic spine and to report long-term results after surgical treatment with hemilaminectomy.

SETTING

Osaka, Japan.

METHODS

A 68-year-old man who had a traumatic intradural arachnoid cyst following an adjacent compression fracture of T5 underwent surgery. Intraoperatively, after recognition of intradural arachnoid cyst with an echogram following hemilaminectomy, the dural sac was incised and the arachnoid cyst was resected under microscopic observation.

RESULTS

At 7 years after the operation, the low intensity within the vertebral body of the compression fracture had resolved and the spinal cord remained in its normal shape and position. No progression of kyphotic deformity was detected.

CONCLUSION

A compression fracture of the thoracic spine can be associated with an intradural arachnoid cyst. Microscopic resection via hemilaminectomy for the cyst showed a good result in a 7-year follow up.

Three cases of acute methyl bromide poisoning in a seedling farm family

We encountered three patients (Patient I: 39-year-old man, Patient II: 34-year-old woman, and Patient III: 5-year-old girl) with acute methyl bromide poisoning, which had occurred as a result of exposure to the gas that leaked from methyl bromide cans stored in a warehouse of a seedling farm. Since all three patients exhibited almost the same initial symptoms, i.e., severe vomiting, tonic convulsions and clouding of consciousness, botulism was suspected at first. However, subsequent inquiry revealed that 27 cans of methyl bromide had been stored in the building that the patients lived in, and that the cans had been damaged a few days before the onset of the patients' illness by a thrashing machine that was being moved by them to another location. Inspection revealed that all the cans of methyl bromide had passed the expiry date and were corroded. Even though none of the cans had been used, three cans with a capacity of 750 g were found to be empty. Plasma bromide ion concentrations were determined to be high (72.9 microg/ml, 67.8 microg/ml and 91.5 microg/ml; normal level, < 5 microg/ml), and acute methyl bromide poisoning was diagnosed 8 days after admission of the patients to the hospital. Hemodialysis (peritoneal lavage in the case of the child) was performed immediately, after which the plasma bromide ion concentrations returned to normal and the general condition of the patients gradually improved.

Effects of posterior cruciate ligament resection on the tibiofemoral joint gap

The effect of posterior cruciate ligament resection on the tibiofemoral joint gap was analyzed in 30 patients with varus osteoarthritis of thee knee who underwent total knee replacement. The medial soft tissue was released and the bone cut was made without preserving the bone segment of the tibia to which the posterior cruciate ligament was attached. Then the medial and lateral joint gaps in full extension and 90 degrees flexion were measured before and after the posterior cruciate ligament was resected using a tensioning device. After the resection, the flexion gap significantly increased in the medial and the lateral sides (4.8 +/- 0.4 and 4.5 +/- 0.4 mm, respectively, mean +/- standard error) compared with those seen in the extension gap (0.9 +/- 0.2 and 0.8 +/- 0.2 mm). There was no significant difference between the changes in the medial and lateral gaps. The mean value of the flexion gap was 2 mm smaller than the extension gap before the resection and 1.7 mm larger after the sacrifice. Overall, posterior cruciate ligament resection resulted in an increase in the flexion gap and made space for approximately 3-mm thicker polyethylene. The flexion gap can be controlled selectively with posterior cruciate ligament release.

Katanosin B and plusbacin A(3), inhibitors of peptidoglycan synthesis in methicillin-resistant Staphylococcus aureus

Both katanosin B and plusbacin A(3) are naturally occurring cyclic depsipeptide antibiotics containing a lactone linkage. They showed strong antibacterial activity against methicillin-resistant Staphylococcus aureus and VanA-type vancomycin-resistant enterococci, with MICs ranging from 0.39 to 3.13 microg/ml, as well as against other gram-positive bacteria. They inhibited the incorporation of N-acetylglucosamine, a precursor of cell wall synthesis, into peptidoglycan of S. aureus whole cells at concentrations close to their MICs. In vitro studies with a wall-membrane particulate fraction of S. aureus showed that katanosin B and plusbacin A(3) inhibited the formation of lipid intermediates, with 50% inhibitory concentrations (IC(50)s) of 2.2 and 2.3 microg/ml, respectively, and inhibited the formation of nascent peptidoglycan, with IC(50)s of 0.8 and 0.4 microg/ml, respectively. Vancomycin, a well-known inhibitor of transglycosylation, did not inhibit the formation of lipid intermediates but did inhibit the formation of nascent peptidoglycan, with an IC(50) of 4.1 microg/ml. Acetyl-Lys-D-Ala-D-Ala, an analog of the terminus of the lipid intermediates, effectively suppressed the inhibition of transglycosylation by vancomycin, but did not suppress those by katanosin B and plusbacin A(3). These results indicate that the antibacterial activity of katanosin B and plusbacin A(3) is due to blocking of transglycosylation and its foregoing steps of cell wall peptidoglycan synthesis via a mechanism differing from that of vancomycin.

Constituents and pH changes in protein rich hyaluronan solution affect the biotribological properties of artificial articular joints

The relationship between the coefficient of friction and pH value or protein constituents of lubricating fluid, together with viscosity, were studied within a bearing surface model for artificial joint, ultra-high molecular weight polyethylene (UHMWPE) against stainless steel (SUS), using a mechanical spectrometer. Four lubricants were tested in this study: sodium hyaluronate (HA), HA with albumin, HA with gamma-globulin, and HA with (L)alpha-dipalmitoyl phosphatidylcholine ((L)alpha-DPPC). The coefficient of friction between UHMWPE and SUS in HA with albumin or HA with gamma-globulin varied from 0.035 to 0.070 depending on angular velocity and pH. The coefficient of friction in HA or HA with (L)alpha-DPPC varied from 0.023 to 0.045 depending on angular velocity and pH. The variation in pH for HA with albumin had a large effect on the coefficient of friction at low range of angular velocity with viscosity independence. The variation in pH for HA with gamma-globulin had a large effect on the coefficient of friction with viscosity dependence at high angular velocity. The addition of (L)alpha-DPPC showed a small effect on the coefficient of friction at low angular velocity. This study confirms that the presence of albumin in the lubricant promotes pH dependence and viscosity independence of the tribological properties at low speed while the presence of globulin promotes pH and viscosity independence at low speed and promotes pH and viscosity dependence at high speed in the lubrication of UHMWPE against SUS. This study supports the clinical hypothesis that the effect of constituents and pH changes in periprosthetic fluid for the lubrication is a clue toward resolving many complications after total joint replacement.

Idiopathic spinal cord herniation associated with intervertebral disc extrusion: a case report and review of the literature

STUDY DESIGN

A case of idiopathic spinal cord herniation is reported, and the literature is reviewed.

OBJECTIVE

To report a case of thoracic spinal cord herniation with a ventral dural defect, probably caused by thoracic disc extrusion.

SUMMARY OF BACKGROUND DATA

Recently, reports of spinal cord herniation have been increasing. This increase can be attributed to the development of magnetic resonance imaging and increased awareness of this entity. However, the cause of the ventral dural defect remains unknown.

METHODS

A 54-year-old woman had experienced Brown-Séquard syndrome for 2 years. Magnetic resonance imaging demonstrated an S-shaped anterior kinking of the spinal cord, with dilation of the dorsal subarachnoid space.

RESULTS

After incision of the dural sac and gentle retraction of the spinal cord, a dural defect was recognized into which the spinal cord had herniated. An extruded disc was visualized through the defect at T3-T4. The ventral dural defect and the dorsal incision of the dural sac were repaired with a fascial graft from the thigh.

CONCLUSIONS

Intraoperative findings suggest that the thoracic disc herniation in the current case was the probable cause of the ventral dural defect. Surgical reconstruction using double fascial graft under careful spinal cord monitoring resulted in a satisfactory neurologic recovery.

Protein purification, cDNA cloning and gene expression of lysozyme from eri-silkworm, Samia cynthia ricini

Lysozyme was isolated from immunized hemolymph of Samia cynthia ricini larvae by heat treatment, cation exchange and reverse-phase chromatography. A cDNA encoding lysozyme was cloned by screening the cDNA library from immunized fat body using, as a probe, a DNA fragment obtained by PCR-based differential display method. The deduced amino acid sequence showed high homology with other chicken-type lysozymes. The calculated molecular mass of the mature peptide was 13785, which agreed precisely with that obtained by MALDI-TOF mass spectrometry of the isolated protein. The lysozyme transcripts were detected at a significant level in naïve fat body, and the level increased 5-10-fold upon injection of the larvae with UV-killed bacteria or peptidoglycan.

Use of folded vascularized rib graft in anterior fusion after treatment of thoracic and upper lumbar lesions. Technical note

For lesions involving the anterior and/or middle column of the spine, an anterior approach is adequate for curetting the lesion and restoring spinal stability. Materials such as autogenous bone grafts, cages with bone chips, some artificial materials, or allografts are used as strut materials. Rib material is usually removed when the anterior approach is conducted for thoracic or thoracolumbar lesions. A rib itself is not rigid enough to support the load, and a bone union is not easily obtained. The purpose of this paper is to describe a method of grafting vascularized rib in folded form to fill the defects left after removal of a spinal lesion. The rib, with the artery and vein at two levels cranial to the involved vertebral body, was isolated from surrounding tissues such as the intercostal nerve, muscles, and pleura. After curetting the lesion, the rib was folded into three or four pieces to a length adequate to fill the defect and inserted as a pedicled vascularized graft. A total of 23 cases, including 14 men and nine women, underwent surgery in which this grafting technique was used. The pathological conditions requiring anterior decompression and fusion were spinal trauma in nine cases, spinal infection in six cases, osteoporotic fracture in seven cases, and spinal metastasis in one case. In all cases a solid bone union was obtained and all infections resolved. With vascularized rib graft folded into three to four pieces, solid bone union can be obtained without use of any other grafted materials even in cases of infection and osteoporosis.

Two novel glucose-6-phosphate dehydrogenase variants found in newborn mass-screening for galactosaemia

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive disorder in which haemolytic anaemia is the major symptom. The Beutler spot test employed in mass-screening for galactosaemia in newborns requires several intrinsic erythrocyte enzymes such as G6PD for its reaction and can theoretically detect G6PD deficiency apart from galactose-1-phosphate uridyltransferase deficiency. In this study, we detected two patients with G6PD deficiency using the quantitative Beutler test which was recently developed in our laboratory. Both patients lacked erythrocyte G6PD activity but exhibited no clinical symptoms. Molecular analysis in patients 1 and 2 revealed two novel missense mutations of C853T causing R285C and A1220C causing K407T, respectively. Molecular rather than enzymatic analysis was required in familial studies to detect and diagnose the carrier state. To date these patients have avoided oxidant stress and haemolytic diatheses have not been induced.

CONCLUSION

Our results indicate that the quantitative Beutler test can detect glucose-6-phosphate dehydrogenase deficiency of class 1 and 2 and is therefore useful for early intervention and prevention of haemolytic diathesis in patients with this disorder.

Transclavicular approach for a large dumbbell tumor in the cervicothoracic junction

Neurogenic dumbbell tumors occur more frequently in the cervical than in the thoracic or lumbar spine. Cervical paravertebral masses usually do not become exceptionally large because they are superficial and are palpated easily. Thoracic tumors can become large before they are detected. The authors describe a large intrathoracic dumbbell tumor arising from the C8 nerve root. The intraspinal tumor was resected through a posterior approach. In the second stage, dividing the clavicle, the intrathoracic component was resected by separating it from the lung. Two years after treatment, the preoperative neurologic deficit had improved except for weakness of muscles innervated by the C8 nerve root. Radiographs showed no residual or recurrent mass at the apex of the lung. Sometimes a retroclavicular location may conceal a large paravertebral mass, such as Pancoast tumors. As described here, the transclavicular approach gave adequate access to the cervicothoracic junction.

Distribution of bone mineral density in the proximal tibia in mid-teens

The distribution of bone mineral density (BMD) in the proximal tibia was studied in 94 knees from 47 mid-teens. The subjects were healthy high school freshmen (19 male; 28 female) who engaged in daily physical exercise. We measured BMD at six regions of interest (ROI) at the bilateral proximal tibia (three immediately above and three immediately be-low the physeal line) using dual-energy X-ray absorptiometry (QDR-2000; Hologic, Waltham, MA, USA). Subjects were supine during the measurements, with the knee extended and the foot fixed in a special holding device, ensuring correct rotational alignment of the knee. Measurements were performed using the forearm array scan mode. The precision of this method (coefficient of variation) was 1.1%-4.9% (mean 2.5%) for six ROIs. The BMD of the medial side was higher than that of the lateral side, and the BMD at the center of the metaphysis was higher than that of the epiphysis. The subjects in the present study did not show any misalignment of the knee joints. These findings indicate that the medial side of the proximal tibia already has higher BMD than the lateral side in teenagers with normal alignment of the knee joint, and that the increase in epiphyseal BMD may be slower than that of metaphyseal BMD. It is suggested that this phenomenon should be life-long and may play a role in the progression of osteoarthritis of the knee.

Nitric oxide regulates mitochondrial respiration and functions of articular chondrocytes

OBJECTIVE

Biologic effects of nitric oxide (NO) have been shown to increase under hypoxic conditions. Because the oxygen tension in joint cavities of patients with arthritis is fairly low, biologic effects of NO would be expected to be significantly large in these compartments. This study was undertaken to investigate the effects of NO on the energy metabolism and functions of articular chondrocytes under different oxygen tension conditions.

METHODS

Articular chondrocytes from rabbits were cultured under various oxygen concentrations in the presence or absence of NO and NOC18, an NO donor. Cellular respiration was measured using a Clark-type oxygen electrode. Levels of ATP in the cells were determined according to the luciferin-luciferase method. Cellular synthesis of proteoglycans was determined by measuring the incorporation of radioactivity (derived from 35S-labeled SO4) into glycosaminoglycans. Expression of stress-related proteins was evaluated by Western blotting analysis using specific antibodies.

RESULTS

Respiration and ATP synthesis of cultured chondrocytes were inhibited by NO, particularly under low oxygen concentrations. The presence of either NO or specific inhibitors of mitochondrial electron transport suppressed the synthesis of proteoglycans without affecting cell viability. When exposed to NO, cellular levels of heat-shock protein 70 (hsp70) and heme oxygenase 1 (HO-1) increased markedly. The presence of inhibitors of mitochondrial electron transport also increased cellular levels of hsp70 and HO-1.

CONCLUSION

These results suggest that NO generated in the joint might inhibit energy metabolism and the synthesis of proteoglycans of chondrocytes, thereby modulating pathophysiologic processes occurring in patients with arthritis.

Stereocontrolled Synthesis of Optically Active beta-D-glucopyranosides of 3-Hydroxy-7,8-didehydro-beta-ionol

A stereocontrolled synthesis of optically active beta-D-glucopyranosides 1-4 of 3-hydroxy-7,8-didehydro-beta-ionol utilizing an asymmetric transfer hydrogenation to alpha,beta-acetylenic ketones catalyzed by chiral ruthenium complexes as the key step is described.

Callotasis for post-traumatic shortening and deformity of leg

We have been performed callotasis, including hemicallotasis, in cases of more than 30 mm limb lengthening and more than 15 degrees angular deformity. There were 21 cases in this series. The mean age was 29.8 years old. Ilizarov external fixator (EF) was used in 13 cases and Orthofix EF in 8. The operation site was femur in 12 cases and tibia in 9 cases. Pre-existed complications were noted to occur in 10 cases. Callotasis was indicated in 17 cases, and the average length gain was 28.4 mm. Hemicallotasis was indicated in 5 cases, and the mean degree of correction angle was 18 degrees. Among available types of EF, Orthofix EF was suitable for proximal femoral callotasis, while Ilizarov EF was suitable for corrective deformity using hemicallotasis and tibial callotasis. The bone healing process of callotsis was better in the absence than presence of pre-existed complication. Also, we performed bone transportation using Ilizarov EF in cases of pseudoarthrosis with leg shortening and in all cases where bone grafting was unnecessary.

A preliminary evaluation of intra- and interindividual variations of hOGG1 messenger RNA levels in peripheral blood cells as determined by a real-time polymerase chain reaction technique

The hOGG1 (8-oxoguanine-DNA glycosylase) gene may contribute to further understanding of the relation between oxidative DNA damage and carcinogenesis. A real-time PCR technique was used to determine mRNA levels in peripheral blood cells to assess the possibility of using hOGG1 mRNA as a biomarker in epidemiological studies. To evaluate the intra- and interindividual variation of hOGG1 mRNA levels in peripheral blood cells, we measured them in five healthy nonsmokers three times over a 1-year period. The beta-actin mRNA level in each subject was set equal to 100, and the levels of hOGG1 mRNA were found to range from 1.6-17.6. The intraindividual variation range was 1.8-6.4. Although the difference in the mRNA levels between the sampling dates was not significant (P = 0.73), a significant difference in mRNA levels was found between the subjects (P < 0.01). The subjects seemed to fall into groups according to their individual levels. This preliminary study may provide initial information on the hOGG1 mRNA level of peripheral blood cells as a biomarker in epidemiological studies on oxygen radicals, oxygen radical-related agents, and cancer.

First total synthesis of mytiloxanthin

The first total synthesis of mytiloxanthin 2 was accomplished via the cyclopentyl ketone 7 prepared by stereoselective rearrangement of the epoxide 4a.

Tibiofemoral movement 3: full flexion in the living knee studied by MRI

We studied active flexion from 90 degrees to 133 degrees and passive flexion to 162 degrees using MRI in 20 unloaded knees in Japanese subjects. Flexion over this arc is accompanied by backward movement of the medial femoral condyle of 4.0 mm and by backward movement laterally of 15 mm, i.e., by internal rotation of the tibia. At 162 degrees the lateral femoral condyle lies posterior to the tibia.

Tibiofemoral movement 3: full flexion in the living knee studied by MRI

We studied active flexion from 90° to 133° and passive flexion to 162° using MRI in 20 unloaded knees in Japanese subjects. Flexion over this arc is accompanied by backward movement of the medial femoral condyle of 4.0 mm and by backward movement laterally of 15 mm, i.e., by internal rotation of the tibia. At 162° the lateral femoral condyle lies posterior to the tibia.

Osteoid osteoma of the cervical spine depicted as dumbbell tumor by MRI

We report a case of 14-year-old male patient with osteoid osteoma of the cervical spine. Magnetic resonance imaging (MRI) revealed a large dumbbell-shaped paravertebral tumor in the region of the exiting left C6 nerve. A computed tomographic (CT) scan after myelography showed a much smaller bony defect in the medial aspect of the left C6 pedicle with central calcification and extensive bone sclerosis around the defect, typical of osteoid osteoma. The diagnosis was confirmed postoperatively. The resected specimen exhibited extensive vascularization of the osteoid tissue. The case is presented because MRI did not allow a specific diagnosis of osteoid osteoma, and suggested the tumor was larger than in reality it was, by also depicting the reactive inflammation around the tumor as if it were part of the tumor.

Low-intensity pulsed ultrasound accelerates bone maturation in distraction osteogenesis in rabbits

We investigated the effects of low-intensity pulsed ultrasound on distraction osteogenesis in a rabbit model. Callotasis of the right tibia was performed in 70 male Japanese white rabbits using mini-external fixators. In the first part of the study in 64 animals using normal distraction (waiting period seven days; distraction rate 0.5 mm/12 hours; distraction period ten days), we evaluated the distraction site by radiography, measurement of the bone mineral density (BMD), mechanical testing, and histology. In the second part in six rabbits using fast distraction (waiting period 0 days; distraction rate 1.5 mm/12 hours; distraction period seven days) the site was evaluated radiologically. Half of the animals (35) had received ultrasound to their right leg (30 mW/cm2) for 20 minutes daily after ceasing distraction (ultrasound group), while rigid fixation only was maintained in the other half (control group). With normal distraction, the hard callus area, as shown by radiography, the BMD, and the findings on mechanical testing, were significantly greater in those receiving ultrasound than in the control group. Histological analysis showed no tissue damage attributable to exposure to ultrasound. With fast distraction, immature bone regeneration was observed radiologically in the control group, while bone maturation was achieved in the ultrasound group. We conclude that ultrasound can accelerate bone maturation in distraction osteogenesis in rabbits, even in states of poor callotasis.

Low-intensity pulsed ultrasound accelerates bone maturation in distraction osteogenesis in rabbits

We investigated the effects of low-intensity pulsed ultrasound on distraction osteogenesis in a rabbit model.

Callotasis of the right tibia was performed in 70 male Japanese white rabbits using mini-external fixators. In the first part of the study in 64 animals using normal distraction (waiting period seven days; distraction rate 0.5 mm/12 hours; distraction period ten days), we evaluated the distraction site by radiography, measurement of the bone mineral density (BMD), mechanical testing, and histology. In the second part in six rabbits using fast distraction (waiting period 0 days; distraction rate 1.5 mm/12 hours; distraction period seven days) the site was evaluated radiologically. Half of the animals (35) had received ultrasound to their right leg (30mW/cm2) for 20 minutes daily after ceasing distraction (ultrasound group), while rigid fixation only was maintained in the other half (control group). With normal distraction, the hard callus area, as shown by radiography, the BMD, and the findings on mechanical testing, were significantly greater in those receiving ultrasound than in the control group. Histological analysis showed no tissue damage attributable to exposure to ultrasound. With fast distraction, immature bone regeneration was observed radiologically in the control group, while bone maturation was achieved in the ultrasound group.

We conclude that ultrasound can accelerate bone maturation in distraction osteogenesis in rabbits, even in states of poor callotasis.