Regulation of ER molecular chaperone prevents bone loss in a murine model for osteoporosis

Endoplasmic reticulum (ER) stress response is important for protein maturation in the ER. Some murine models for bone diseases have provided significant insight into the possibility that pathogenesis of osteoporosis is related to ER stress response of osteoblasts. We examined a possible correlation between osteoporosis and ER stress response. Bone specimens from 8 osteoporosis patients and 8 disease-controls were used for immunohistochemical analysis. We found that ER molecular chaperones, such as BiP (immunoglobulin heavy-chain binding protein) and PDI (protein-disulfide isomerase) are down-regulated in osteoblasts from osteoporosis patients. Based on this result, we hypothesized that up-regulation of ER molecular chaperones in osteoblasts could restore decreased bone formation in osteoporosis. Therefore, we investigated whether treatment of murine model for osteoporosis with BIX (BiP inducer X), selective inducer BiP, could prevent bone loss. We found that oral administration of BIX effectively improves decline in bone formation through the activation of folding and secretion of bone matrix proteins. Considering these results together, BIX may be a potential therapeutic agent for the prevention of bone loss in osteoporosis patients.     

Cocrystallization and amorphization induced by drug-excipient interaction improves the physical properties of acyclovir

Although acyclovir is one of the most important antiviral drugs used today, there are several problems with its physical properties. The aim of this study is to prepare cocrystals or amorphous complex of acyclovir using drug-excipient interactions to improve the physical properties of the drug, especially its dissolution rate and transdermal absorption. Screening for formation of cocrystals and the presence of amorphous acyclovir was conducted with various pharmaceutical excipinents, with the use of the solution-crystallization method and liquid-assisted cogrinding. The potential cocrystalline phase and the amorphized complex were characterized by PXRD, TG/DTA, IR, DSC and HPLC techniques. The screening indicated that acyclovir formed novel cocrystals with tartaric acid and was amorphized with citric acid. The acyclovir-tartaric acid cocrystal (ACV-TA cocrystal) structure was determined from synchrotron X-ray powder diffraction data. T(g) of the amorphous acyclovir-citric acid compound (ACV-CA amorphous) was determined by DSC. The initial dissolution rate of the ACV-TA cocrystals was considerably faster than that of anhydrous acyclovir. In vitro skin permeation of ACV-CA amorphous from polyethylene glycol (PEG) ointment was remarkably higher than that of the crystalline acyclovir. We successfully improved the physical properties of acyclovir by the cocrystallization and amorphization techniques, using pharmaceutical excipients.     

Root canal system of the maxillary canine

To better assess the efficacy of mechanical preparation of root canals, transparent specimens of 250 extracted maxillary canines were investigated for canal configuration, thickness and curvature of the root canal, condition of any accessory canals, and location of the apical foramen. Fewer than 40% of the specimens showed accessory canals that were mechanically impossible to clean. The majority of the lateral branches were small, greater than a #15 file, and none of the branches were larger than a #20 file. Although apical foramina located away from the apex were observed in 30% of the maxillary teeth, 96% of all apical foramina were within 0.5 mm of the apex. Data on the thickness of the root and main canal in the apical portion and curvature of the root canal suggest that, for adequate apical preparation, a #60 file must be able to reach the apical constriction.     

17beta-estradiol protects cortical neurons against oxidative stress-induced cell death through reduction in the activity of mitogen-activated protein kinase and in the accumulation of intracellular calcium

Although many studies have suggested that estrogen acts as a neuroprotective agent in oxidative stress, the underlying mechanism has not been fully elucidated. In the present study, we examined the effect of 17beta-estradiol (17beta-E2) on H(2)O(2)-induced death signaling in cultured cortical neurons. Exposure of the cortical neurons to H(2)O(2) triggered a series of events, including overactivation of p44/42 MAPK and intracellular Ca(2+) accumulation via voltage-gated Ca(2+) channels and ionotropic glutamate receptors, resulting in apoptotic-like cell death. The MAPK pathway might work as death signaling in our system, because the MAPK pathway inhibitor, U0126, blocked H(2)O(2)-induced MAPK activation, Ca(2+) overload, and cell death. Interestingly, a similar inhibitory effect on H(2)O(2)-triggered MAPK activation, Ca(2+) accumulation, and cell death was observed in cultures incubated with 17beta-E2 for 24 h before exposure to H(2)O(2), suggesting that the protective effect of 17beta-E2 is induced via attenuating overactivation of the MAPK pathway. Furthermore, we found that ionotropic glutamate receptor subunits, including NR2A and GluR2/3, but not NR2B and GluR1, were down-regulated in the 17beta-E2-treated cultures. The down-regulation of these glutamate receptor subunits was also observed after chronic treatment with U0126. Therefore, it is possible that 17beta-E2 down-regulates the expression of the ionotropic glutamate receptors by reducing activity of the MAPK pathway, which might be important for the protective effect of 17beta-E2 against oxidative stress-induced toxicity.     

Potential of Periodontal Ligament Cells to Regenerate Alveolar Bone

Regeneration of periodontal tissues, lost as a result of periodontal disease, is a key objective of periodontal treatment. Although several periodontal regeneration therapies have been devised, the origin of the undifferentiated cells that regenerate periodontal tissues remains unknown. Therefore, in the present study, to clarify the existence of osteoblast progenitor cells in the periodontal ligament, as well as to investigate the mechanism of alveolar bone regeneration without any effects from the original bone, we evaluated osteoblast differentiation induced by transplantation of GFP-transgenic rat molars into the subcutaneous tissues of wild-type rats. Ten days after transplantation, initial alveolar bone was formed apart from the cementum in the bifurcation region. After 20 days, this bone tissue had expanded to almost all of the bifurcation. GFP localization showed that the osteoblasts were derived from the transplant. Alpha-SMA- and BMP4-positive cells were observed near the root surface at 5 days after transplantation. With the progress of alveolar bone regeneration, osteoblasts expressing Runx2 and Osterix appeared in the bone-forming region. These results indicate that periodontal ligament tissue remaining on the root surface after a tooth extraction contains undifferentiated cells that have the ability to regenerate alveolar bone. The process of osteoblast differentiation in this model might be similar to that for normal alveolar bone formation. Thus, periodontal ligament cells might be useful for the regeneration of alveolar bone in tissue engineering applications.     

Myosin-dependent endoplasmic reticulum motility and F-actin organization in plant cells

Plants exhibit an ultimate case of the intracellular motility involving rapid organelle trafficking and continuous streaming of the endoplasmic reticulum (ER). Although it was long assumed that the ER dynamics is actomyosin-driven, the responsible myosins were not identified, and the ER streaming was not characterized quantitatively. Here we developed software to generate a detailed velocity-distribution map for the GFP-labeled ER. This map revealed that the ER in the most peripheral plane was relatively static, whereas the ER in the inner plane was rapidly streaming with the velocities of up to ∼3.5 μm/sec. Similar patterns were observed when the cytosolic GFP was used to evaluate the cytoplasmic streaming. Using gene knockouts, we demonstrate that the ER dynamics is driven primarily by the ER-associated myosin XI-K, a member of a plant-specific myosin class XI. Furthermore, we show that the myosin XI deficiency affects organization of the ER network and orientation of the actin filament bundles. Collectively, our findings suggest a model whereby dynamic three-way interactions between ER, F-actin, and myosins determine the architecture and movement patterns of the ER strands, and cause cytosol hauling traditionally defined as cytoplasmic streaming.     

Serial brain imaging analysis of stroke-like episodes in MELAS

We report 2 patients of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and consider the pathophysiology of stroke-like lesions, using magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI) on MRI, perfusion imaging on MRI, and 1H magnetic resonance spectroscopy (1H-MRS). In Patient 1, T2-weighted imaging (T2-WI) on MRI at onset and even at 44 days after onset of the stroke-like episode showed high intensity in left parietal, temporal, and occipital lobe lesions. In the temporal lobe lesion, the apparent diffusion coefficient (ADC) at 44 days after onset was higher (average: 1.219x10(-3)mm2/s) than that in a normal region (average: 0.796x10(-3)mm2/s). (1)H-MRS of the left parietal lobe lesion at the same day showed a decrease in N-acetylaspartate/(creatine+phosphocreatine) (NAA/Cr) (0.43) and a peak in lactate. 1H-MRS of the contralateral side at the same day showed NAA/Cr (1.57) and no peak in lactate. Thereafter, ADC gradually decreased and NAA/Cr gradually increased, and the peak in lactate disappeared in the lesion. In Patient 2, T2-WI at onset showed high intensity in bilateral occipital lobe lesions. In the left occipital lobe lesion, ADC at the same day was higher (1.082x10(-3)mm2/s) than that in a normal region (average: 0.841x10(-3)mm2/s). (1)H-MRS of the left occipital lobe lesion at the same day showed a decrease of NAA (3.0mM) and a peak in lactate (13.1mM) (measured by LCModel). In 1H-MRS of the normal left parietooccipital lobe at 4 months before onset, NAA was 7.6mM and there was no peak in lactate (0mM). Perfusion imaging at onset showed high intensity in bilateral occipital lobes, which indicated hyperperfusion in stroke-like lesions. Thereafter, ADC gradually decreased and the peak in lactate partially decreased, and the low concentration of NAA persisted (regardless of the partial recovery) in the lesion. These results suggest that the stroke-like episodes is related to vasogenic edema, hyperperfusion, and neuronal damage. Acute oxidative phosphorylation defect may have a crucial role in the pathophysiology of stroke-like episodes.     

Neurocognitive function of patients with brain metastasis who received either whole brain radiotherapy plus stereotactic radiosurgery or radiosurgery alone

PURPOSE: To determine how the omission of whole brain radiotherapy (WBRT) affects the neurocognitive function of patients with one to four brain metastases who have been treated with stereotactic radiosurgery (SRS). METHODS AND MATERIALS: In a prospective randomized trial between WBRT+SRS and SRS alone for patients with one to four brain metastases, we assessed the neurocognitive function using the Mini-Mental State Examination (MMSE). Of the 132 enrolled patients, MMSE scores were available for 110. RESULTS: In the baseline MMSE analyses, statistically significant differences were observed for total tumor volume, extent of tumor edema, age, and Karnofsky performance status. Of the 92 patients who underwent the follow-up MMSE, 39 had a baseline MMSE score of < or =27 (17 in the WBRT+SRS group and 22 in the SRS-alone group). Improvements of > or =3 points in the MMSEs of 9 WBRT+SRS patients and 11 SRS-alone patients (p = 0.85) were observed. Of the 82 patients with a baseline MMSE score of > or =27 or whose baseline MMSE score was < or =26 but had improved to > or =27 after the initial brain treatment, the 12-, 24-, and 36-month actuarial free rate of the 3-point drop in the MMSE was 76.1%, 68.5%, and 14.7% in the WBRT+SRS group and 59.3%, 51.9%, and 51.9% in the SRS-alone group, respectively. The average duration until deterioration was 16.5 months in the WBRT+SRS group and 7.6 months in the SRS-alone group (p = 0.05). CONCLUSION: The results of the present study have revealed that, for most brain metastatic patients, control of the brain tumor is the most important factor for stabilizing neurocognitive function. However, the long-term adverse effects of WBRT on neurocognitive function might not be negligible.