Proof-of-Principle Experiment for Testing Strong-Field Quantum Electrodynamics with Exotic Atoms: High Precision X-Ray Spectroscopy of Muonic Neon

To test bound-state quantum electrodynamics (BSQED) in the strong-field regime, we have performed high precision x-ray spectroscopy of the 5g-4f and 5f- 4d transitions (BSQED contribution of 2.4 and 5.2 eV, respectively) of muonic neon atoms in the low-pressure gas phase without bound electrons. Muonic atoms have been recently proposed as an alternative to few-electron high-Z ions for BSQED tests by focusing on circular Rydberg states where nuclear contributions are negligibly small. We determined the 5g_{9/2}- 4f_{7/2} transition energy to be 6297.08±0.04(stat)±0.13(syst)  eV using superconducting transition-edge sensor microcalorimeters (5.2-5.5 eV FWHM resolution), which agrees well with the most advanced BSQED theoretical prediction of 6297.26 eV.

Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision Spectroscopy of Electronic K X Rays

We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic Kα and Kβ x rays together with the hypersatellite K^{h}α x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K- and L-shell hole production and their temporal evolution on the 10-20 fs scale during the muon cascade process.

New precise measurements of muonium hyperfine structure at J-PARC MUSE

High precision measurements of the ground state hyperfine structure (HFS) of muonium is a stringent tool for testing bound-state quantum electrodynamics (QED) theory, determining fundamental constants of the muon magnetic moment and mass, and searches for new physics. Muonium is the most suitable system to test QED because both theoretical and experimental values can be precisely determined. Previous measurements were performed decades ago at LAMPF with uncertainties mostly dominated by statistical errors. At the J-PARC Muon Science Facility (MUSE), the MuSEUM collaboration is planning complementary measurements of muonium HFS both at zero and high magnetic field. The new high-intensity muon beam that will soon be available at H-Line will provide an opportunity to improve the precision of these measurements by one order of magnitude. An overview of the different aspects of these new muonium HFS measurements, the current status of the preparation for high-field measurements, and the latest results at zero field are presented.

Orbital Selectivity in Scanning Tunneling Microscopy: Distance-Dependent Tunneling Process Observed in Iron Nitride

In scanning tunneling microscopy, orbital selectivity of the tunneling process can make the topographic image dependent on a tip-surface distance. We have found reproducible dependence of the images on the distance for a monatomic layer of iron nitride formed on a Cu(001) surface. Observed atomic images systematically change between a regular dot array and a dimerized structure depending on the tip-surface distance, which turns out to be the only relevant parameter in the image variation. An accompanied change in the weight of Fe-3d local density of states to a tunneling background was detected in dI/dV spectra. These have been attributed to a shift in surface orbitals detected by the tip from the d states to the s/p states with increasing the tip-surface distance, consistent with an orbital assignment from first-principles calculations.

Pressure-induced valence crossover and novel metamagnetic behavior near the antiferromagnetic quantum phase transition of YbNi_{3}Ga_{9}

We report electrical resistivity, ac magnetic susceptibility, and x-ray absorption spectroscopy measurements of intermediate valence YbNi_{3}Ga_{9} under pressure and magnetic field. We have revealed a characteristic pressure-induced Yb valence crossover within the temperature-pressure phase diagram, and a first-order metamagnetic transition is found below P_{c}∼9  GPa where the system undergoes a pressure-induced antiferromagnetic transition. As a possible origin of the metamagnetic behavior, a critical valence fluctuation emerging near the critical point of the first-order valence transition is discussed on the basis of the temperature-field-pressure phase diagram.

Structural, magnetic and electronic state characterization of L1 0-type ordered FeNi alloy extracted from a natural meteorite

To understand the hard magnetism of L10-type ordered FeNi alloy, we extracted the L10-FeNi phase from a natural meteorite, and evaluated its fundamental solid-state properties: sample composition, magnetic hysteresis, crystal structure and electronic structure. We executed multidirectional analyses using scanning electron microscopy with an electron probe micro-analyzer (SEM-EPMA), a superconducting quantum interference device (SQUID), x-ray diffraction (XRD) and magnetic circular dichroism (MCD). As a result, we found that the composition was Fe: 50.47 ± 1.98 at.%, Ni: 49.60 ± 1.49 at.%, and an obvious superlattice peak is confirmed. The estimated degree of order was 0.608, with lattice constants a = b = 3.582 Å and c = 3.607 Å. The obtained coercivity was more than 500 Oe. MCD analysis using the K absorption edge suggests that the magnetic anisotropy could originate from the orbital magnetic moment of 3d electrons in Fe; this result is consistent with that in a previous report obtained with synthetic L10-FeNi.

Immunohistochemical localization of aggresomal proteins in glial cytoplasmic inclusions in multiple system atrophy

AIMS

Multiple system atrophy (MSA) is pathologically characterized by the formation of α-synuclein-containing glial cytoplasmic inclusions (GCIs) in oligodendrocytes. However, the mechanisms of GCI formation are not fully understood. Cellular machinery for the formation of aggresomes has been linked to the biogenesis of the Lewy body, a characteristic α-synuclein-containing inclusion of Parkinson's disease and dementia with Lewy bodies. Here, we examined whether GCIs contain the components of aggresomes by immunohistochemistry.

METHODS

Sections from five patients with MSA were stained immunohistochemically with antibodies against aggresome-related proteins and analysed in comparison with sections from five patients with no neurological disease. We evaluated the presence or absence of aggresome-related proteins in GCIs by double immunofluorescence and immunoelectron microscopy.

RESULTS

GCIs were clearly immunolabelled with antibodies against aggresome-related proteins, such as γ-tubulin, histone deacetylase 6 (HDAC6) and 20S proteasome subunits. Neuronal cytoplasmic inclusions (NCIs) were also immunopositive for these aggresome-related proteins. Double immunofluorescence staining and quantitative analysis demonstrated that the majority of GCIs contained these proteins, as well as other aggresome-related proteins, such as Hsp70, Hsp90 and 62-kDa protein/sequestosome 1 (p62/SQSTM1). Immunoelectron microscopy demonstrated immunoreactivities for γ-tubulin and HDAC6 along the fibrils comprising GCIs.

CONCLUSIONS

Our results indicate that GCIs, and probably NCIs, share at least some characteristics with aggresomes in terms of their protein components. Therefore, GCIs and NCIs may be another manifestation of aggresome-related inclusion bodies observed in neurodegenerative diseases.

Dietary patterns and risk of Parkinson's disease: a case-control study in Japan

BACKGROUND

Nearly all epidemiologic studies examining the association between the risk of Parkinson's disease (PD) and diet have focused on single foods and specific nutrients. However, epidemiologic evidence for the association of dietary pattern with PD, namely the measurement of overall diet by considering the cumulative effects of nutrients is extremely limited. We conducted a hospital-based case-control study in Japan to examine the relationship between dietary patterns and the risk of PD.

METHODS

Patients with PD diagnosed using the UK PD Society Brain Bank criteria (n = 249) and controls without neurodegenerative diseases (n = 368) were recruited. At the time of recruitment, dietary intake during the preceding 1 month was assessed using a validated, self-administered diet history questionnaire. Dietary patterns from 33 predefined food groups (energy-adjusted food g/day) were extracted by factor analysis.

RESULTS

Three dietary patterns were identified: 'Healthy', 'Western' and 'Light meal' patterns. After adjustment for potential non-dietary confounding factors, the Healthy pattern, characterized by a high intake of vegetables, seaweed, pulses, mushrooms, fruits and fish, was inversely associated with the risk of PD with a border-line significance (P for trend = 0.06). Multivariate Odds ratio (95% confidence intervals) for PD in the highest quartile of the Healthy pattern was 0.54 (0.32-0.92) compared with the lowest quartile. No associations with PD were detected for the other two dietary patterns.

CONCLUSION

In this case-control study in Japan, a dietary pattern consisting of high intakes of vegetables, fruits and fish may be associated with a decreased risk of PD.

[Successful chemotherapy of carcinomatosis of the bone marrow with disseminated intravascular coagulation from a rectal carcinoma found by eosinophilia]

A 71-year-old man with eosinophilia was given a diagnosis of poorly differentiated adenocarcinoma of the rectum. Further examination showed that it had invaded the bone marrow. He had disseminated intravascular coagulation (DIC) from disseminated carcinomatosis of the bone marrow after colostomy. Chemotherapy (mFOLFOX6) was successful and his eosinophil count, DIC score and tumor markers normalized. We were able to continue chemotherapy after 5 months from the outbreak of disseminated carcinomatosis of the bone marrow. It is said that disseminated carcinomatosis of the bone marrow has a poor prognosis, but we were able to obtain a good response in this case by chemotherapy.

Dietary intake of antioxidant vitamins and risk of Parkinson's disease: a case-control study in Japan

BACKGROUND

antioxidant vitamins are expected to protect cells from oxidative damage by neutralizing the effects of reactive oxygen species. However, epidemiological evidence regarding the associations between antioxidant vitamin intake and Parkinson's disease (PD) is limited and inconsistent. We investigated the relationship between dietary intake of selected antioxidant vitamins, vegetables and fruit and the risk of PD in Japan using data from a multicenter hospital-based case-control study.

METHODS

included were 249 patients within 6 years of onset of PD. Controls were 368 inpatients and outpatients without a neurodegenerative disease. Information on dietary factors was collected using a validated self-administered diet history questionnaire. Adjustment was made for sex, age, region of residence, pack-years of smoking, years of education, body mass index, dietary intake of cholesterol, alcohol, total dairy products, and coffee and the dietary glycemic index.

RESULTS

higher consumption of vitamin E and β-carotene was significantly associated with a reduced risk of PD after adjustment for confounders under study: the adjusted odds ratio in the highest quartile was 0.45 (95% confidence interval [CI]: 0.25-0.79, P for trend = 0.009) for vitamin E and 0.56 (95% CI: 0.33-0.97, P for trend = 0.03) for β-carotene. Stratified by sex, such inverse associations were significant only in women. No material relationships were shown between intake of vitamin C, α-carotene, cryptoxanthin, green and yellow vegetables, other vegetables, or fruit and the risk of PD.

CONCLUSIONS

higher intake of vitamin E and β-carotene may be associated with a decreased risk of PD.

Lack of association of dairy food, calcium, and vitamin D intake with the risk of Parkinson's disease: a case-control study in Japan

Three previous cohort studies in the USA reported that dairy product consumption was significantly associated with an increased risk of Parkinson's disease (PD) in men, but not in women. We examined the relationship between consumption of dairy products, calcium, and vitamin D and the risk of PD using data from a multicenter hospital-based case-control study in Japan. Included were 249 cases within 6 years of onset of PD based on the UK PD Society Brain Bank clinical diagnostic criteria. Controls were 368 inpatients and outpatients without a neurodegenerative disease. Information on dietary factors was collected using a validated self-administered diet history questionnaire. Adjustment was made for sex, age, region of residence, pack-years of smoking, years of education, body mass index, and dietary factors including cholesterol, dietary glycemic index, vitamin E, β-carotene, vitamin B(6), caffeine, iron, and alcohol. Total dairy product consumption was not materially associated with the risk of PD (P for trend = 0.62). No evident relationships were observed between intake of milk, yogurt, cheese, or ice cream and the risk of PD (P for trend = 0.75, 0.63, 0.59, and 0.35, respectively). There were no measurable associations between consumption of calcium or vitamin D and PD (P for trend = 0.37 and 0.69, respectively). No significant interactions were observed between the dietary exposures and sex regarding PD. Our results suggest that intake of dairy products, calcium, and vitamin D was not related to PD, regardless of sex. However, such null relationships might be a consequence of PD.

Active and passive smoking and risk of Parkinson's disease

OBJECTIVE

To assess the association between active and passive smoking and the risk of Parkinson's disease (PD), a case-control study with 249 PD patients and 369 controls was carried out in Japan.

METHODS

Information on smoking was obtained through a self-administered questionnaire. Adjustment was made for age, sex, region of residence, educational level, and occupational exposure.

RESULTS

Ever having smoked cigarettes was associated with a reduced risk of PD [adjusted odds ratio = 0.38; 95% confidence interval (CI): 0.24-0.59]. Risk for former smokers was intermediate between the high risk for never smokers and the low risk for current smokers. Adjusted odds ratios for former and current smokers were 0.51 (95% CI: 0.32-0.82) and 0.12 (95% CI: 0.05-0.26), respectively. There was an inverse dose-response gradient with pack-years smoked. No significant association was detected for passive smoking exposure.

CONCLUSION

Our results appear to confirm data from previous epidemiological studies.

Phenotypic spectrum of hereditary neuralgic amyotrophy caused by the SEPT9 R88W mutation

BACKGROUND

Hereditary neuralgic amyotrophy (HNA), also known as hereditary brachial plexus neuropathy, has phenotypic and genetic heterogeneity. Mutations in the septin 9 (SEPT9) gene were recently identified in some HNA patients. The phenotypic spectrum of HNA caused by SEPT9 mutations is not well known.

OBJECTIVE

To characterise the phenotype of a large family of HNA patients with the SEPT9 R88W mutation.

METHODS

We report clinical, electrophysiological, neuroimaging and genetic findings of six HNA patients from a Japanese family.

RESULTS

All 17 neuropathic episodes identified were selectively and asymmetrically distributed in the upper-limb nerves. Severe pain was an initial symptom in 16 episodes (94%). Motor weakness occurred in 15 (88%) and sensory signs in 10 (59%). A minor dysmorphism, hypotelorism, was seen in all. Nerve conduction studies revealed focal demyelination as well as prominent axonal degeneration changes. Needle electromyography revealed chronic neurogenic patterns only in the upper limbs. An MRI study showed a gadolinium-enhanced brachial plexus. The missense mutation c.262C>T; p.R88W was found in exon 2 of SEPT9 in all patients.

CONCLUSIONS

The SEPT9 R88W mutation in this family causes selective involvement of the brachial plexus and upper-limb nerves. Wider and more universal recognition of clinical hallmarks and genetic counselling are of diagnostic importance for HNA caused by the SEPT9 mutation.

[A case of primary adenocarcinoma of small intestine with multiple liver metastases successfully treated with mFOLFOX6]

A 60-year-old man was referred to our hospital since his stool examination was positive for occult blood. Colonoscopy showed a tumor of Bauhin's valve and terminal ileum. Biopsy of the tumor was performed and pathological examination revealed adenocarcinoma. No other lesions were detected by gastroduodenoscopy and double-balloon enteroscopy. CT also showed multiple liver metastases. Ileocecal resection was performed because of severe stenosis of the terminal ileum. Histopathological examination revealed moderately-differentiated adenocarcinoma of Bauhin's valve and the terminal ileum, and no adenocarcinoma was found in the cecum and ascending colon. He was diagnosed with primary adenocarcinoma of the ileum with multiple liver metastases. Chemotherapy with mFOLFOX6 was performed after surgical resection. After 5 courses of chemotherapy, abdominal CT showed marked regression of the liver metastases, and tumor marker (CA19-9) was normalized from 1,100 U/mL to 36 U/mL. Effectiveness of mFOLFOX6 for primary adenocarcinoma of small intestine is suggested.

Neural damage associated with atopic diathesis: a nationwide survey in Japan

BACKGROUND

We previously reported the occurrence of myelitis in patients with atopic disorders (atopic myelitis [AM]). To uncover the spectrum of neural damage associated with atopy, we conducted a cross-sectional nationwide survey of AM and atopy-related peripheral neuritis (APN), including Churg-Strauss syndrome (CSS), in individuals with atopic diathesis.

METHOD

Cases with AM diagnosed between 1996 and 2006 and cases with APN between 2000 and 2006 were collected from all over Japan. Detailed data on 109 patients with AM and 133 patients with APN were collated.

RESULTS

Patients with APN showed a preponderance of women, higher age at onset, and greater eosinophil counts than patients with AM. Patients with AM most commonly showed cervical cord involvement, whereas patients with APN preferentially exhibited mononeuritis multiplex predominantly affecting the lower limbs. Among patients with AM, motor weakness and muscle atrophy were significantly more frequent in those with bronchial asthma than in those with other atopic disorders. Patients with APN who met the criteria for CSS showed a higher age at onset, higher frequencies of systemic organ involvement, and greater disability than those who did not. Abnormalities suggesting peripheral nervous system involvement were seen in 25.7% of patients with AM, whereas 18.8% of patients with APN had abnormalities indicating CNS involvement. Multiple logistic regression analyses revealed that atopic dermatitis increased the risk of myelitis, whereas high age at onset and bronchial asthma decreased that risk.

CONCLUSIONS

Atopy-related neural inflammation multifocally affects CNS and peripheral nervous system tissues. Both preceding atopic disorders and age seem to influence the distribution of neural damage.

X-ray magnetic circular dichroism of a valence fluctuating state in eu at high magnetic fields

X-ray magnetic circular dichroism (XMCD) at the Eu L edge in two compounds exhibiting valence fluctuation, namely EuNi_{2}(Si_{0.18}Ge_{0.82})_{2} and EuNi_{2}P_{2}, has been investigated at high magnetic fields of up to 40 T. A distinct XMCD peak corresponding to the trivalent state (Eu(3+)), whose ground state is nonmagnetic (J = 0), was observed in addition to the main XMCD peak corresponding to the magnetic (J = 7/2) divalent state (Eu(2+)). This result indicates that the 5d electrons belonging to both valence states are magnetically polarized. It was also found that the ratio P_{5d}(3+)/P_{5d}(2+) between the polarization of 5d electrons (P_{5d}) in the Eu(3+) state and that of Eu(2+) depends on the material. The possible origin of the XMCD and an explanation of the material dependence of P_{5d}(3+)/P_{5d}(2+) are discussed in terms of hybridization between the conduction electrons and the f electrons.

XAS and XMCD study of the influence of annealing on the atomic ordering and magnetism in an NiMnGa alloy

The proper annealing of Ni(51)Mn(28)Ga(21) ribbon alloy gives rise to an increase of the saturation magnetization and of the magnetic order T(C) (up to 20 K) and martensitic transition T(M) (up to 10 K) temperatures. The combined x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) studies indicate that the annealing treatment drives the alloy to a more ordered structure without significantly affecting the local structure in terms of interatomic distances and bonding geometry. By contrast, the annealing strongly affects the near-edge absorption at the Mn K-edge while no effect is observed at either the Ni or Ga K-edge. These results suggest that annealing leads to a modification of the electronic structure of the Mn atoms while that of Ni and Ga atoms remains unvaried. However, strong XMCD signals are detected at both Ni and Ga K-edges whose amplitude increases after annealing. These results point out that despite the change of the magnetic properties of the system being mainly associated with the modification of the electronic properties of the Mn atoms, both Ni and Ga may play a non-negligible role through the polarization of the conduction band.

Diffuse large B-cell lymphoma with massive portal vein tumor thrombosis in a patient with alcoholic cirrhosis: a case report and literature review

We describe a case of diffuse large B-cell lymphoma with massive portal vein tumor thrombosis in a patient with alcoholic cirrhosis. The tumor was detected only in the intrahepatic portal vein and the spermatic cord by FDG-PET/CT. Percutaneous liver biopsy and orchiectomy were performed and histological examination revealed diffuse large B-cell lymphoma. The tumor showed complete response after six courses of the combination chemotherapy. Portal vein tumor thrombosis of malignant lymphoma is extremely rare; moreover, it is possible that this is the first case of malignant lymphoma originating from the spermatic cord producing portal vein tumor thrombosis.

Preparation of ortho-para ratio controlled D2 gas for muon-catalyzed fusion

A negative muon in hydrogen targets, e.g., D2 or D-T mixture, can catalyze nuclear fusions following a series of atomic processes involving muonic hydrogen molecular formation (muon-catalyzed fusion, muCF). The ortho-para state of D2 is a crucial parameter not only for enhancing the fusion rate but also to precisely investigate various muonic atom processes. We have developed a system for controlling and measuring the ortho-para ratio of D2 gas for muCF experiments. We successfully collected para-enriched D2 without using liquid-hydrogen coolant. Ortho-enriched D2 was also obtained by using a catalytic conversion method with a mixture of chromium oxide and alumina. The ortho-para ratio of D2 gas was measured with a compact Raman spectroscopy system. We produced large volume (5-30 l at STP), high-purity (less than ppm high-Z contaminant) D2 targets with a wide range of ortho-para ratios (ortho 20%-99%). By using the ortho-para controlled D2 in muCF experiments, we observed the dependence of muCF phenomena on the ortho-para ratio.

Limbic structures are prone to age-related impairments in proteasome activity and neuronal ubiquitinated inclusions in SAMP10 mouse: a model of cerebral degeneration

AIMS

Neurodegenerative diseases are characterized by ubiquitinated inclusions in selective brain regions. Here we investigated whether the dysfunction of the ubiquitin proteasome system might be involved in the pathogenesis and regional selectivity of neuronal ubiquitinated inclusions using the SAMP10 strain of mouse, an inbred model of age-related cerebral degeneration.

METHODS

By comparing SAMP10 mice at various ages with SAMR1 and C57BL mice as normal brain ageing controls, we studied morphological features and distribution of inclusions. We measured tissue proteasome activity in different brain regions of mice at various ages by fluorogenic substrate assays. We induced inclusions in cultured neurones by inhibiting the proteasome and analysed changes in the dendritic morphology.

RESULTS

Inclusions were formed in association with lipofuscin in neuronal perikarya and occurred most frequently in the limbic-related forebrain structures. There were sparse inclusion-bearing neurones in the non-limbic forebrain. In aged SAMR1 and C57BL, there were far fewer inclusions in the limbic-related forebrain than in aged SAMP10. The proteasome activity in the limbic-related forebrain decreased much more rapidly and remarkably upon ageing (26% activity was detected in 17-month-old compared with 3-month-old mice) in SAMP10 than in SAMR1. The proteasome activity in the non-limbic forebrain did not change significantly with advancing age in either SAMP10 or SAMR1. Proteasomal inhibition enhanced the formation of ubiquitinated inclusions in cultured neurones. Neurones bearing inclusions had shortened neurites.

CONCLUSIONS

We propose that the regional selectivity of proteasomal impairment is causally related to the selectivity of inclusion formation and associated dendritic degeneration in neurones of ageing SAMP10 mice.

Hypercalcemia in childhood acute lymphoblastic leukemia: frequent implication of parathyroid hormone-related peptide and E2A-HLF from translocation 17;19

Hypercalcemia is relatively rare but clinically important complication in childhood leukemic patients. To clarify the clinical characteristics, mechanisms of hypercalcemia, response to management for hypercalcemia, incidence of t(17;19) and final outcome of childhood acute lymphoblastic leukemia (ALL) accompanied by hypercalcemia, clinical data of 22 cases of childhood ALL accompanied by hypercalcemia (>12 mg/dl) reported in Japan from 1990 to 2005 were retrospectively analyzed. Eleven patients were 10 years and older. Twenty patients had low white blood cell count (<20 x 10(9)/l), 15 showed hemoglobin> or =8 g/dl and 14 showed platelet count > or =100 x 10(9)/l. Parathyroid hormone-related peptide (PTHrP)-mediated hypercalcemia was confirmed in 11 of the 16 patients in whom elevated-serum level or positive immunohistochemistry of PTHrP was observed. Hypercalcemia and accompanying renal insufficiency resolved quickly, particularly in patients treated with bisphosphonate. t(17;19) or add(19)(p13) was detected in five patients among 17 patients in whom karyotypic data were available, and the presence of E2A-HLF was confirmed in these five patients. All five patients with t(17;19)-ALL relapsed very early. Excluding the t(17;19)-ALL patients, the final outcome of ALL accompanied by hypercalcemia was similar to that of all childhood ALL patients, indicating that the development of hypercalcemia itself is not a poor prognostic factor.

Dentin resorption and cementum-like tissue formation by bone morphogenetic protein application

BACKGROUND AND OBJECTIVE

Recent studies have shown that bone morphogenetic protein-2 (BMP-2) stimulates mineralization and osteoclast differentiation. Osteoclastic resorption by BMP-2 application may play an important role in the regulation of new cementum-like tissue formation on the dentin surfaces. Therefore, this study aimed to examine the effect of BMP-2 application on dentin resorption and cementum-like tissue formation at the dentin surfaces.

MATERIAL AND METHODS

Seventy-two flat dentin blocks were prepared from rat roots and treated with 24% EDTA. Each block was assigned to group 0, group 100, or group 400, and immersed correspondingly in 0, 100, or 400 microg/ml BMP-2. The dentin blocks were then implanted into palatal connective tissue of rats, and specimens were prepared 2, 4 and 8 wk after surgery for histologic and histomorphometric analyses.

RESULTS

BMP-2 caused a dose-dependent increase in dentin resorption by osteoclastic cells. New cementum-like tissue was randomly formed on parts of the nonresorbed and resorbed dentin surfaces in groups 100 and 400. Dentin resorption in groups 100 and 400 was significantly greater than group 0 (p < 0.01). However, at 8 wk, new cementum-like tissue formed in 41.8% of group 100, as compared with 16.2% of group 400 (p < 0.05).

CONCLUSION

Dentin resorption was stimulated by a high dose of BMP-2, and cementum-like tissue was induced by a low dose of BMP-2, effectively suggesting that BMP-2 application, at an appropriate dose, to a dentin surface may enhance periodontal regeneration.