Expression of membrane type 1 matrix metalloproteinase, matrix metalloproteinase 2 and tissue inhibitor of metalloproteinase 2 in human cartilaginous tumors with special emphasis on mesenchymal and dedifferentiated chondrosarcoma

Membrane type 1 matrix metalloproteinase (MT1-MMP) has been identified as an activator of the proenzyme of matrix metalloproteinase 2 (MMP-2: gelatinase A), and has also been shown to play a crucial role in tumor invasion by activating proMMP2 in both lung and gastric carcinoma. The tissue inhibitor of metalloproteinase 2 (TIMP-2) plus the MT1-MMP complex also plays an important role in the activation of proMMP-2. In this study, the expressions of MT1-MMP, MMP-2 and TIMP-2 were evaluated in 10 enchondromas, 34 conventional chondrosarcomas, 5 clear-cell chondrosarcomas, 7 mesenchymal chondrosarcomas and 8 dedifferentiated chondrosarcomas. The expressions were immunohistochemically visualized on paraffin sections and the levels of expression were assessed semiquantitatively. The extent of staining was assessed by the extent score in order to determine the overall level of expression. The extent scores of MT1-MMP, MMP-2 and TIMP-2 in grade 2 chondrosarcoma were significantly higher than those in either enchondroma or grade 1 chondrosarcoma (P < 0.05). In conventional chondrosarcoma, significant correlations were found between the extent scores of MT1-MMP and MMP-2 (P < 0.001), MT1-MMP and TIMP-2 (P < 0.01), and MMP-2 and TIMP-2 (P < 0.01). The undifferentiated small round tumor cells of mesenchymal chondrosarcoma showed lower positive rates and extent scores for MT1-MMP (2/7, 0.7 +/- 0.5) and MMP-2 (3/7, 0.7 +/- 0.4) than for cartilaginous components of mesenchymal chondrosarcoma [MT1-MMP (4/7, 1.3 +/- 0.5) and MMP-2 (7/7, 1.9 +/- 0.3)] or conventional chondrosarcoma. In dedifferentiated chondrosarcoma, the extent scores of MT1-MMP, MMP-2 and TIMP-2 in low-grade cartilaginous components were not significantly different from those in conventional chondrosarcoma; however, the high-grade anaplastic components showed high extent scores for MT1-MMP, MMP-2 and TIMP-2, compared with the low-grade cartilaginous components of dedifferentiated chondrosarcoma or conventional chondrosarcoma. According to our results, the expression of MT1-MMP as well as that of MMP-2 or TIMP-2 demonstrated a significant correlation with the tumor grade in human cartilaginous tumors. Furthermore, the expressions of MT1-MMP, MMP-2 and TIMP-2 were also found to play a crucial role in invasion in the high-grade components of dedifferentiated chondrosarcoma.

[Clinical analysis of thrombocytopenia in chronic dialysis patients]

Thrombopoietic status in dialysis patients is controversial. This study addressed this issue by analyzing factors associated with thrombopoiesis. One hundred and fifty-one dialysis patients(119 HD and 32 CAPD) and 41 age-matched control subjects were studied. Thrombocytopenia was defined as a platelet count less than 150 x 10(9)/l. Reticulated platelets(RET), a marker for marrow megakaryopoiesis, were measured using thiazole orange dye by flowcytometry. Serum thrombopoietin (TPO) level was measured by ELISA. Hepatitis C virus(HCV) antibody, platelet-associated IgG(PAIgG), and other clinical parameters were examined in the patients. The platelet counts in the HD patients were significantly lower than those in the CAPD or controls. The incidence of thrombocytopenia was 30.0% in the HD patients. Thrombocytopenia was more prominent in the HCV-infected HD patients in whom PAIgG was mostly positive(81.8%) and its titer was remarkably high(102.9 +/- 92.7 pg/ml). There were significant differences in the RET counts between patients with and without thrombocytopenia. None of the other parameters, such as iPTH, beta 2 microglobulin, and Kt/V, nor any prescribed drugs were related to thrombocytopenia. Serum TPO was significantly higher in HD patients(135.9 +/- 60.1 pg/ml) than in the controls(97.0 +/- 53.4 pg/ml). In conclusion, thrombocytopenia is frequent in HD patients, especially in HCV-infected HD patients. Reduced marrow magakaryopoiesis is mostly responsible for thrombocytopenia and peripheral destruction of platelets could be, in part, involved. Mild elevation of serum TPO possibly indicates a counter-response to decreased mass of megakaryocyte in bone marrow.

Posterior tibial slope in the normal and varus knee

Posterior tibial slope was evaluated in 30 normal and 30 varus knees using magnetic resonance imaging. The mean tibial posterior slope in the medial plateau was 10.7 degrees (range: 5 degrees - 15.5 degrees) in the normal knees and 9.9 degrees (range: 1.5 degrees - 19 degrees) in the varus knees. The mean tibial posterior slope in the lateral plateau was 7.2 degrees (range: 0 degrees - 14.5 degrees) in the normal knees and 6 degrees (range: 1 degrees - 13 degrees) in the varus knees. Although these differences were not statistically significant, there was a large range in the posterior tibial slope in both groups. When 10-mm thickness of bone was resected in the middle of the lateral plateau in total knee arthroplasty, the thickness of the bone resection in the anterior and posterior part of the lateral plateau was measured. The presumed thickness of bone was 10.1 mm (range: 7.3-13.9 mm) in the anterior part and 7.5 mm (range: 5-10.3 mm) in the posterior part. A large range in the measured thickness of bone also was detected in the varus knees. These results suggest that the shape of the proximal tibia varies among individuals and that the cutting angle should be determined in each case to avoid any mismatch of the patient's posterior slope of the tibia after implantation.

Knee stability in posterior cruciate ligament retaining total knee arthroplasty

Anteroposterior knee laxity was evaluated in 14 patients (19 knees) who had posterior cruciate ligament retaining total knee arthroplasty using the Miller Galante I prosthesis. The followup ranged from 87 to 118 months (average, 105.9 months), and the measurements were done using the KT-2000 arthrometer. The mean anteroposterior displacement with the knees with Miller Galante I prostheses was 10.1 mm at 30 degrees flexion and 8.1 mm at 75 degrees flexion. In the 15 knees with Miller Galante I prostheses with flexion greater than 90 degrees, seven had less stability at 75 degrees than at 30 degrees flexion. These knees were considered to have a nonfunctional posterior cruciate ligament, and they had a worse Knee Society score (81.1) than did the other eight knees with Miller Galante I prostheses (89.9). There were four knees in which the flexion was less than 90 degrees. In this study, approximately half of the knees with posterior cruciate ligament retaining total knee arthroplasty did not have good anteroposterior stability in flexion an average of 9 years after surgery.

Balloon-occluded retrograde transvenous obliteration of gastric varix draining via the left inferior phrenic vein into the left hepatic vein

We encountered a patient with gastric varix draining not via the usual left suprarenal vein but via the left inferior phrenic vein joining the left hepatic vein. Transfemoral balloon-occluded retrograde transvenous obliteration (BRTO) of the varix was performed under balloon occlusion of the left inferior phrenic vein via the left hepatic vein and retrograde injection of the sclerosing agent (5% of ethanolamine oleate) into the gastric varix. Disappearance of the gastric varix was confirmed on endoscopic examination 2 months later.

Saccade-related inhibitory input to pontine omnipause neurons: an intracellular study in alert cats

Omnipause neurons (OPNs) are midline pontine neurons that are thought to control a number of oculomotor behaviors, especially saccades. Intracellular recordings were made from OPNs in alert cats to elucidate saccade-associated postsynaptic events in OPNs and thereby determine what patterns of afferent discharge impinge on OPNs to cause their saccadic inhibition. The membrane potential of impaled OPNs exhibited steep hyperpolarization before each saccade that lasted for the whole period of the saccade. The hyperpolarization was reversed to depolarization by intracellular injection of Cl- ions, indicating it consisted of temporal summation of inhibitory postsynaptic potentials (IPSPs). The duration of the saccade-related hyperpolarization was almost equal to the duration of the concurrent saccades. The time course of the hyperpolarization was similar to that of the radial eye velocity except for the initial phase. During the falling phase of eye velocity, the correlation between the instantaneous amplitude of hyperpolarization and the instantaneous eye velocity was highly significant. The amplitude of hyperpolarization at the eye velocity peak was correlated significantly with the peak eye velocity. The time integral of the hyperpolarization was correlated with the radial amplitude of saccades. The initial phase disparity between the hyperpolarization and eye velocity was due to the relative constancy of peak time (approximately 20 ms) of the initial steep hyperpolarization regardless of the later potential profile that covaried with the eye velocity. The initial steep hyperpolarization led the beginning of saccades by 15.9 +/- 3.8 (SD) ms, which is longer than the lead time for medium-lead burst neurons. These results demonstrate that the pause of activity in OPNs is caused by IPSPs initiated by an abrupt, intense input and maintained, for the whole duration of the saccade, by afferents conveying eye velocity signals. We suggest that the initial sudden inhibition originates from central structures such as the superior colliculus and frontal eye fields and that the eye velocity-related inhibition originates from the burst generator in the brain stem.

Analysis of oestrogen receptor mRNA by reverse transcriptase-polymerase chain reaction in human periodontal ligament cells

Periodontal ligament (PDL) cells have osteoblast-like features and are capable of differentiating into osteogenic cells. As human osteoblasts express oestrogen receptor mRNA, it is possible that PDL cells do so also, but findings have been conflicting. To determine whether they do express oestrogen receptor mRNA, the reverse transcriptase-polymerase chain reaction was performed with two different primers. Cells were obtained from a healthy periodontal ligament of premolar extracted for orthodontic reasons. The human breast adenocarcinoma cell-line MCF7 was used as a positive control. Expression of oestrogen receptor mRNA was detected in PDL cells with one of the primers but with less intensity than in MCF7 cells. Southern hybridization confirmed these results. These findings suggest that PDL cells express oestrogen receptor mRNA at low levels.

An adult case of recurrent arteriovenous malformation after "complete" surgical excision: a case report

BACKGROUND

Complete surgical excision of arteriovenous malformations (AVM) documented by postoperative angiography is considered a cure. However, recent reports have shown that AVMs in children may recur after negative postoperative angiograms, and some suggest that it may reflect the immaturity of their cerebrovasculature. This case report demonstrates that AVM in adults may also recur, despite postoperative angiograms confirming complete removal.

CASE DESCRIPTION

This 28-year-old man presented in 1994 with a focal motor seizure and was found to have an AVM in the right frontal lobe. He underwent surgical excision of the AVM; postoperative angiograms taken immediately after surgery and 15 days later showed no residual AVM. He remained free of symptoms after surgery and it was considered that a complete removal had been achieved. In 1998 he developed a subarachnoid hemorrhage, and subsequent angiograms revealed a small AVM in an adjacent location.

CONCLUSION

This is the oldest patient reported in the literature with a recurrence of AVM, despite postoperative angiograms confirming complete removal. Angiographically invisible immature vessels, which might have been left in the surgical field, might have formed a new malformation later. We still believe that such recurrence must be very rare after AVM surgery, but we now recommend follow-up angiography at yearly intervals to our patients.

Genetic polymorphism of renin-angiotensin system is not associated with diabetic vascular complications in Japanese subjects with long-term insulin dependent diabetes mellitus

In a hospital cohort study, we examined whether or not ACE (Angiotensin-I converting enzyme) and AGT (Angiotensinogen) gene polymorphisms were associated with the development of nephropathy in long-term Japanese insulin-dependent diabetes mellitus (IDDM) patients with or without proliferative retinopathy, and whether or not the polymorphisms were associated with an arteriosclerotic family history in first degree relatives of the patients. A total of 201 patients with IDDM for more than 10 years and 159 patients with IDDM for more than 15 years were randomly selected in our hospital. All patients received uniform diabetes management and were divided into three groups, no nephropathy, incipient nephropathy and clinical nephropathy groups. There were no differences in clinical characteristics excluding urinary albumin to creatinine ratio and systolic blood pressure between the three groups. ACE I/D polymorphism was related to plasma ACE activity, but there were no associations between ACE I/D polymorphism and the development of diabetic nephropathy, nor was renal deterioration observed in patients with proliferative retinopathy even in those with a history of diabetes for more than 15 years. The AGT polymorphism did not have an additive effect on the association between ACE polymorphism and the development of diabetic nephropathy in patients with or without retinopathy. Development of diabetic nephropathy in the patients with or without proliferative retinopathy did not result in ACE or AGT polymorphisms. On the other hand, the ACE DD genotype was associated with a family history of ischemic heart disease in first degree relatives (X2 score = 9.04, P < 0.05). ACE and AGT gene polymorphisms may not play a role in the protective or accelerative effect against the development of diabetic nephropathy in the patients with or without proliferative retinopathy, but ACE gene polymorphism might be related to an arteriosclerotic family history in Japanese IDDM patients.

Spatial alignment of rotational and static tilt responses of vestibulospinal neurons in the cat

The responses of vestibulospinal neurons to 0.5-Hz, whole-body rotations in three-dimensional space and static tilts of whole-body position were studied in decerebrate and alert cats. The neurons' spatial properties for earth-vertical rotations were characterized by maximum and minimum sensitivity vectors (R(max) and R(min)) in the cat's horizontal plane. The orientation of a neuron's R(max) was not consistently related to the orientation of its maximum sensitivity vector for static tilts (T(max)). The angular difference between R(max) and T(max) was widely distributed between 0 degrees and 150 degrees, and R(max) and T(max) were aligned (i.e., within 45 degrees of each other) for only 44% (14/32) of the neurons. The alignment of R(max) and T(max) was not correlated with the neuron's sensitivity to earth-horizontal rotations, or to the orientation of R(max) in the horizontal plane. In addition, the extent to which a neuron exhibited spatiotemporal convergent (STC) behavior in response to vertical rotations was independent of the angular difference between R(max) and T(max). This suggests that the high incidence of STC responses in our sample (56%) reflects not only canal-otolith convergence, but also the presence of static and dynamic otolith inputs with misaligned directionality. The responses of vestibulospinal neurons reflect a complex combination of static and dynamic vestibular inputs that may be required by postural reflexes that vary depending on head, trunk, and limb orientation, or on the frequency of stimulation.

Increased level of apolipoprotein B/apolipoprotein A1 ratio as a potential risk for osteonecrosis

OBJECTIVE

This study was performed to investigate whether a high ratio of apolipoprotein B to apolipoprotein A1 (apo B/apo A1 ratio) is significantly associated with the risk of developing non-traumatic osteonecrosis of the femoral head (ON).

METHODS

Fifty consecutive non-traumatic ON cases were compared with 50 age and sex matched controls, using both univariate and stepwise discriminant analyses, regarding the factors of corticosteroid, alcohol, cigarettes, cholesterol, triglyceride, and apo B/apo A1 ratio. To eliminate the possibility that ON or osteoarthritic change itself can increase the apo B/apo A1 ratio, a further 32 consecutive cases comprising nine traumatic ON and 23 osteoarthritis (OA) patients were analysed using Scheffe's test.

RESULTS

There was a significant association between a high apo B/apo A1 ratio and the development of non-traumatic ON with both univariate (p=0.0001) and stepwise discriminant analyses (partial r(2)=0.1239, p=0.0004). The apo B/apo A1 ratio in the non-traumatic ON group was significantly higher than that in the traumatic ON (p<0.01), control (p<0.001), or the OA groups (p<0.001).

CONCLUSION

A high apo B/apo A1 ratio is significantly associated with the risk of developing ON. This ratio may be useful for assessing the potential risk of developing osteonecrosis.

Increased activity of membrane glycoprotein PC-1 in the fibroblasts from non-insulin-dependent diabetes mellitus patients with insulin resistance

Although most of patients with non-insulin-dependent diabetes mellitus (NIDDM) have insulin resistance, it is unknown whether a molecule might interfere with insulin action. Membrane glycoprotein PC-1 (plasma cell antigen-1), which inhibits insulin receptor tyrosine kinase activity, was isolated from fibroblasts of NIDDM patients. Because PC-1 content in skeletal muscle and adipose tissue correlated with whole body insulin sensitivity, PC-1 might play a role in insulin resistance. In order to know whether PC-1 activity of fibroblasts is also elevated in Japanese NIDDM patients, and whether PC-1 activity correlates with the parameters of insulin resistance in vivo or not, we measured PC-1 activity of cultured fibroblasts from 17 patients with NIDDM and seven healthy controls. PC-1 activity of the NIDDM patients was 85.2 +/- 33.1 nmol/mg per min (mean +/- S.D.), and was higher than that of healthy controls (42.6 +/- 12.7 nmol/mg per min, P = 0.0002). Insulin sensitivity was measured in 11 of 17 NIDDM patients by the artificial pancreas. PC-1 activity of the patients with insulin resistance (glucose infusion rate < 3.0 mg/kg per min, n = 7) was elevated to 99.9 +/- 31.9 nmol/mg per min, while that of the other patients (n = 4) was 55.3 +/- 7.5 nmol/mg per min (P = 0.003). In conclusion, glycoprotein PC-1 activity of dermal fibroblasts is correlated with insulin resistance in patients with NIDDM.

Serum and urinary concentrations of heparan sulfate in patients with diabetic nephropathy

BACKGROUND

Heparan sulfate (HS) contributes to the negative charge in the glomerular basement membrane (GBM), which may maintain the GBM charge barrier. Changes in sulfation and/or the concentration of HS may be associated with the development of diabetic nephropathy.

METHODS

Using two different antibodies specific for HS chains, one that reacts with the N-sulfated sequences in HS chains (10E4) and the other that reacts with neo-epitope of HS, which occurs after heparitinase digestion of HS chains (3G10), we examined the serum and urinary concentrations of HS by enzyme-linked immunosorbent assay and performed immunohistochemical staining of glomeruli in diabetic patients with and without nephropathy.

RESULTS

The level of urinary excretion of 10E4 binding HS/creatinine clearance was significantly reduced in diabetic patients when compared with that in nondiabetic subjects (P < 0.0001), and the level was more decreased in patients with overt nephropathy than in patients without overt nephropathy. No differences or only small differences were found between these groups in serum and urinary 3G10-binding HS and in serum 10E4-binding HS. Immunohistochemical staining with these antibodies was consistent with the findings in the urine.

CONCLUSIONS

The results suggest that a decreased HS N-sulfation exists in the urine, which may reflect a structural change or an altered processing of HS within the GBM. Because N-sulfation plays a key role in determining the extent of sulfation within the HS chains, the decreased urinary 10E4-binding HS may have potential implications with regard to the development of diabetic nephropathy.

Changes in knee alignment after total knee arthroplasty

Changes in limb alignment after total knee arthroplasty were evaluated in 20 knees replaced with the Miller Galante knee system. The mean follow-up period was 87.4 months. Seventeen of the 20 knees were in the varus position on the initial postoperative radiographs, but the alignment significantly changed to become even more aligned toward varus during the follow-up period. The thickness of the ultra-high-molecular-weight polyethylene (UHMWPE) also decreased significantly in the medial femorotibial joint. The wear of the UHMWPE possibly changed the alignment, and the postoperative alignment had a positive correlation with the wear rate. The components should be implanted so that the mechanical axis intersects the center of the components to prevent worsening of alignment as well as to minimize any such wear.

Effects of sex hormones on production of interleukin-1 by human peripheral monocytes

BACKGROUND

Interleukin-1 (IL-1) is a potent mediator of inflammation and is known to induce bone resorption. We studied the effects of sex hormones on the function of human monocytes and demonstrated that prostaglandin E2 (PGE2) production was enhanced by progesterone and estradiol. As PGE2 has been shown to suppress the production of IL-1 by monocytes, it was speculated that sex hormones also modify the production of IL-1 by regulating PGE2 production. Thus, the effects of sex hormones on the production of IL-1 from human peripheral monocytes and the influence of PGE2 were investigated.

METHODS

Mononuclear leukocytes were obtained from 22 healthy adults. Progesterone, 17-beta estradiol (estradiol), and testosterone were used as representative sex hormones. Monocytes were incubated at 37 degrees C in air with 5% CO2 for 24 hours in RPMI 1640 medium with sex hormones at the designated concentrations. LPS (Salmonella typhimurium) was used to stimulate the monocytes at a concentration of 10 microg/ml. The concentrations of IL-1alpha and IL-1beta in the medium were determined by enzyme-linked immunosorbent assay kits. The concentration of PGE2 was determined using a direct radio-immunoassay kit. Indomethacin was used to inhibit the synthesis of PGE2 and eliminate its effect on the production of IL-1.

RESULTS

Estradiol at concentrations of 0.04 ng/ml or more significantly reduced both IL-1alpha and IL- 1beta production. Progesterone also reduced IL-1alpha and IL-1beta production significantly at concentrations of 0.1 ng/ml or more and 0.02 ng/ml or more, respectively. The reductions in IL- 1alpha and IL-1beta production by sex hormones were not affected by addition of indomethacin.

CONCLUSIONS

Estradiol and progesterone inhibited the production of IL-1 from human peripheral monocytes. The inhibition was not the result of enhanced production of PGE2. Under conditions in which sex hormone levels are low, monocytes produce IL- more readily in response to stimulation by LPS than high levels of such hormones. Low concentrations of sex hormones may be considered as one of the risk factors for periodontitis.

The effect of hydroxyapatite coating on the bonding of bone to titanium implants in the femora of ovariectomised rats

We have studied the effect of hydroxyapatite (HA) coating in 15 ovariectomised and 15 normal rats which had had a sham procedure. Twenty-four weeks after operation, HA-coated implants were inserted into the intramedullary canal of the right femur and uncoated implants into the left femur. The prostheses were removed four weeks after implantation. Twelve specimens in each group had mechanical push-out tests. Sagittal sections of the other three were evaluated by SEM.

The bone mineral density (BMD) of the dissected left tibia was measured by dual-energy x-ray absorptiometry. The difference in BMD between the control and ovariectomised tibiae was 35.01 mg/cm2 (95% CI, 26.60 to 43.42). The push-out strength of the HA-coated implants was higher than that of the uncoated implants in both groups (p < 0.0001), but the HA-coated implants of the ovariectomised group had a reduction in push-out strength of 40.3% compared with the control group (p < 0.0001).

Our findings suggest that HA-coated implants may improve the fixation of a cementless total hip prosthesis but that the presence of osteoporosis may limit the magnitude of this benefit.

VMH lesions reduce excessive running under the activity-stress paradigm in the rat

We have previously shown that excitation of certain neurons in the ventromedial nucleus of the hypothalamus (VMH) of rats induces hyperrunning activity. The present study investigated the involvement of these VMH neurons in inducing excessive running under the activity-stress paradigm. The VMH of 6-week-old male rats was bilaterally lesioned by administration of kainic acid. Control animals received saline in the VMH. They were housed in running-wheel activity cages with free access to food for 6 days of the recovering period, and then fed 1 h each day for 6 days. Control animals exhibited marked increases in both running activity and its light/dark ratio, and developed stomach ulcers. In contrast, animals with bilateral VMH lesions showed a significantly attenuated increase in running activity and no change in light/dark ratio. VMH lesions also suppressed stomach ulceration. These results suggest that VMH neurons play a crucial role in inducing excessive running and stomach ulceration during exposure to the activity-stress paradigm.

The effect of hydroxyapatite coating on the bonding of bone to titanium implants in the femora of ovariectomised rats

We have studied the effect of hydroxyapatite (HA) coating in 15 ovariectomised and 15 normal rats which had had a sham procedure. Twenty-four weeks after operation, HA-coated implants were inserted into the intramedullary canal of the right femur and uncoated implants into the left femur. The prostheses were removed four weeks after implantation. Twelve specimens in each group had mechanical push-out tests. Sagittal sections of the other three were evaluated by SEM. The bone mineral density (BMD) of the dissected left tibia was measured by dual-energy x-ray absorptiometry. The difference in BMD between the control and ovariectomised tibiae was 35.01 mg/cm2 (95% CI, 26.60 to 43.42). The push-out strength of the HA-coated implants was higher than that of the uncoated implants in both groups (p < 0.0001), but the HA-coated implants of the ovariectomised group had a reduction in push-out strength of 40.3% compared with the control group (p < 0.0001). Our findings suggest that HA-coated implants may improve the fixation of a cementless total hip prosthesis but that the presence of osteoporosis may limit the magnitude of this benefit.

Cartilage and labrum degeneration in the dysplastic hip generally originates in the anterosuperior weight-bearing area: an arthroscopic observation

To clarify the intra-articular pathology of dysplastic osteoarthritis, we conducted 120 hip arthroscopies. Hips were classified radiologically into four stages: 41 prearthritic stage, 42 early-stage, 34 advanced-stage, and 3 end-stage. As the radiological stage progressed, articular cartilage degeneration became more extensive and severe. In the prearthritic and early stages, cartilage degeneration generally originated in the anterosuperior portion of the weight-bearing area of the femoral head and acetabulum. Cartilage degeneration of the acetabulum usually preceded that of the femoral head. Most detaching tears of the acetabular labrum originated in the anterosuperior area, too. In conclusion, cartilage and labrum degeneration in the dysplastic hip generally originates in the anterosuperior portion of weight-bearing area.

Present state of dental health knowledge, attitudes/behaviour and perceived oral health of Japanese employees

The aim of this survey was to assess the present state of dental health knowledge, attitudes/behaviour and perceived oral health of Japanese employees. A 60-item questionnaire was used in a dental health project in the work place. The subjects comprised 77,845 employees, 76 per cent of whom reported delaying a dental visit until they had toothache, with about 60 per cent delaying even when they discovered a decayed tooth. The majority did not regard decayed teeth as a disease and only a minority reported regular dental visits. About three quarters reported bleeding gums on brushing, although more than half had never been taught professionally how to clean their teeth and less than 5 per cent flossed daily. More than half believed that false teeth were inevitable in old age, and that their teeth were getting worse despite daily brushing. About 70 per cent of the employees thought that it was impossible to prevent gum disease with toothbrushing alone, and nearly half believed a toothpaste with fluoride was effective in preventing periodontal disease. Reorientation of oral health care in Japan, therefore, is urgently needed and dental services have to be provided for the implementation of systematic oral health promotion for employees in the workplace.

Assessment of subchondral bone blood flow in the rabbit femoral condyle using the laser speckle method

The laser speckle method is a new form of flowmetry that can obtain a two-dimensional distribution of blood flow in tissue. This method is a noncontact, simple, and rapid technique that may aid in the diagnosis of osteonecrosis. We investigated whether the subchondral bone blood flow within the femoral condyles of rabbits could be measured by the laser speckle method. The hydrogen washout method was chosen as a comparison technique because of its ability to allow repetitive measurements of blood flow in various conditions in one rabbit and because of its reliability, which already has been established. We simultaneously measured the bone blood flow in 20 femoral condyles of 10 rabbits with the laser speckle and hydrogen washout methods and found a significant correlation between the blood flow levels with use of these two methods. For the clinical application of the laser speckle method, we also investigated the influence of cartilage thickness on the measurements and the depth in the bone to which blood flow could be measured with this method. A cartilage thickness of 0.2 mm did not influence the measurement of the bone blood flow, and the depth in the bone to which the laser speckle method could be used was approximately 2 mm.

A new, all-inside technique for meniscus repair

A new method for arthroscopic meniscal repair using sutures with multiple knots was developed, and its mechanical strength was evaluated. Sutures are passed arthroscopically through the torn meniscus using a needle with a cleft in its tip, and when the needle is withdrawn, knots are placed both in the meniscus and the joint capsule. Our method does not require additional skin incisions and can be performed for repair of posterior tears. Furthermore, this all-inside technique minimizes the risk of popliteal neurovascular injury. Biomechanical analysis using bovine menisci showed that the maximum frictional force between the suture and meniscus was greater than the maximum strength of a suture itself. Our method is simple and rapid, making it easy to insert multiple sutures to achieve adequate stability.

Axonal trajectories of the nucleus reticularis gigantocellularis neurons in the C2-C3 segments in cats

Axonal trajectories in the C2-C3 segments of the nucleus reticularis gigantocellularis neurons projecting to the lower cervical cord (C-RSNs) and excited monosynaptically from cortico- and tectofugal fibers were studied by mapping thresholds of antidromic excitation and intra-axonal staining in cats. The C-RSNs descended in various sites of the spinal funiculi, and the projection area of individual cells varied with the funicular location of the stem axon. C-RSNs descending in the ventrolateral funiculus (inRSNs) projected mainly to lamina VIII-IX, those descending in the lateral funiculus (IRSNs) mainly to laminae VI-VIII, and those descending in the contralateral funiculus (coRSNs) chiefly to laminae VIII-IX on that side. It is suggested that inRSNs and coRSNs mediate disynaptic effects from cortico- and tectofugal fibers to dorsal neck motoneurons bilaterally.