Central odontogenic fibroma with osteoid formation showing atypical radiographic appearance

We recently encountered an interesting tumour, containing both a diffuse sclerotic border and calcified bodies, which was eventually diagnosed as a central odontogenic fibroma. The patient was a 40-year-old man with a painless radiolucent area in the crown area of the unerupted left lower third molar shown by panoramic radiography. Clinically, the lesion was thought to represent an odontogenic tumour involving a calcified body, i.e. calcifying cystic odontogenic tumour, calcifying epithelial odontogenic tumour or ossifying fibroma. Diagnosis by radiographic findings was extremely difficult.

Relationship between period of survival and clinicopathological characteristics in patients with colorectal liver metastasis

AIM

Cancer death in the early period after hepatectomy still occurs in patients with colorectal liver metastasis (CLM). We examined the relationship between clinicopathological parameters and survival periods in 130 CLM patients who underwent hepatectomy.

PATIENTS/METHODS

Patients were divided into four groups: Group 1 (5-year survivors without tumor relapse), Group 2 (survivors at 2-5 years), Group 3 (cancer death at 2-5 years), and Group 4 (cancer death within 2 years).

RESULTS

A short surgical margin was frequent in Group 4 compared to Group 1 (31 vs. 78%, P<0.05). Primary node-positive status, absence of fibrous pseudo-capsular formation, higher Clinical Risk Score, and tumor recurrence within 12 months were frequent in Group 4 (P<0.05). Multivariate analysis revealed a short surgical margin (HR; 3.5) and early tumor relapse (HR; 5.9) as independently significant related parameters (P<0.05).

CONCLUSIONS

Sufficient surgical margins and careful follow-up for early tumor relapse may be important for improving postoperative outcomes for CLM patients.

Correlation between histopathological image and radiographic image pattern in fibro-osseous lesions in relation to bone complexity and distribution

OBJECTIVES

This study examined correlations between radiographic patterns and the shape of osteoid tissue formations, as determined histopathologically.

METHODS

20 cases of fibro-osseous lesions were investigated, comprising 5 radiographic patterns: focal (n = 3), target (n = 6), lucent (n = 4), calcification (n = 3) and multiconfluent (n = 4). Histopathological images in the central area of a full-section specimen were transformed into binary images and then into 8-bit scale images. Bone complexity and density of bone distribution were calculated and compared between patterns.

RESULTS

Bone complexity score was 7384.64 for lucent, 2029.85 for focal, 2713.40 for multiconfluent, 8388.63 for calcification and 1364.27 for target pattern. The results could be broadly separated into two types: small (target, focal and multiconfluent patterns), and large (lucent and calcification patterns). Density of bone distribution was relatively low in all areas for lucent and calcification patterns, and high for focal, multiconfluent and target patterns. No significant differences in bone complexity or density of bone distribution were seen between individual patterns.

CONCLUSIONS

Correlations appear to exist between image patterns from radiography and the shape of osteoid tissue on histopathology, but reorganization of the five patterns may be warranted.

Effects of acute exercise on visual reaction time

We examined the effects of acute exercise on reaction time to visual stimuli presented in the central portion and periphery of the visual field. Twelve participants performed reaction time tasks at rest and during cycling at 65 % peak oxygen uptake in two visual conditions. We used circular black-and-white checkerboard patterns as visual stimuli. The participants were asked to respond as quickly as possible to pattern reversal of the visual stimulus by releasing a response button. Reaction time was fractionated into Premotor time and Motor time. Premotor time in the peripheral condition significantly increased (p < 0.025) during exercise (mean +/- SE; 195.9 +/- 7.9 ms) from that at rest (183.7 +/- 6.8 ms). Premotor time in the central condition did not differ between at rest (185.3 +/- 7.6 ms) and during exercise (188.4 +/- 6.6 ms). These data suggest that the ability to respond to visual stimuli presented in the periphery of the visual field is vulnerable to moderate to severe exercise, as compared with the ability to respond to visual stimuli presented in the central portion of the visual field. An exercise-induced increase in arousal level and a consequent narrowing of attentional focus would explain the present results.

Usefulness of cone beam computed tomography for odontogenic myxoma

A case of odontogenic myxoma is reported as showing a cyst-like pattern with a partially thick but vague and unclear radiopaque border between the left mandibular second premolar and first molar on rotational panoramic radiography. Internal structure of the lesion displayed radiolucency with a sparse and coarse trabecular pattern. No expansion of bucco-lingual cortical bone was apparent. The radiographic pattern of odontogenic myxoma did not resemble a tennis racket-like or straight, curved and coarse septal appearance on panoramic radiography, but characteristic findings were noted on cone beam CT. Cone beam CT may prove extremely useful in clarifying detailed internal structure and the state of margins.

A role for Cdc2- and PP2A-mediated regulation of Emi2 in the maintenance of CSF arrest

BACKGROUND

Vertebrate oocytes are arrested in metaphase II of meiosis prior to fertilization by cytostatic factor (CSF). CSF enforces a cell-cycle arrest by inhibiting the anaphase-promoting complex (APC), an E3 ubiquitin ligase that targets Cyclin B for degradation. Although Cyclin B synthesis is ongoing during CSF arrest, constant Cyclin B levels are maintained. To achieve this, oocytes allow continuous slow Cyclin B degradation, without eliminating the bulk of Cyclin B, which would induce release from CSF arrest. However, the mechanism that controls this continuous degradation is not understood.

RESULTS

We report here the molecular details of a negative feedback loop wherein Cyclin B promotes its own destruction through Cdc2/Cyclin B-mediated phosphorylation and inhibition of the APC inhibitor Emi2. Emi2 bound to the core APC, and this binding was disrupted by Cdc2/Cyclin B, without affecting Emi2 protein stability. Cdc2-mediated phosphorylation of Emi2 was antagonized by PP2A, which could bind to Emi2 and promote Emi2-APC interactions.

CONCLUSIONS

Constant Cyclin B levels are maintained during a CSF arrest through the regulation of Emi2 activity. A balance between Cdc2 and PP2A controls Emi2 phosphorylation, which in turn controls the ability of Emi2 to bind to and inhibit the APC. This balance allows proper maintenance of Cyclin B levels and Cdc2 kinase activity during CSF arrest.

The thickness of the roof of the glenoid fossa in the temporomandibular joint: relationship to the MRI findings

OBJECTIVES

The purpose of this study was to clarify the relationship between the thickness of the roof of the glenoid fossa (RGF) and magnetic resonance imaging (MRI) findings of temporomandibular joint (TMJ) disorders (TMDs).

METHODS

Eighty-seven patients with symptoms and indications of TMD in one or both TMJs were referred for MRI. Cone-beam CT (3DX) was used to measure the thickness of the RGF at its thinnest point. Linear measurements were made three times on the monitor by three separate investigators and the mean values obtained were used for the statistical analyses.

RESULTS

The joints were categorised as normal (70 joints), anterior disc displacement with reduction (ADWR; 53 joints) or anterior disc displacement without reduction (ADWOR; 51 joints). The joint disorders were also categorised into the following subgroups: with osteoarthritis (OA) (21 joints), without OA (153 joints), with disc deformation (33 joints), without disc deformation (141 joints), with joint effusion (JE) (61 joints) and without JE (113 joints). The average minimum thickness of the RGF was 0.85 mm for normal joints, 0.90 mm with ADWR, 0.93 mm with ADWOR, 0.99 mm with OA, 0.87 mm without OA, 0.87 mm with disc deformation and 0.89 mm without disc deformation. There was no significant difference between these figures. There was a significant difference in the thickness of the RGF with (0.97 mm) and without (0.84 mm) JE.

CONCLUSIONS

These results suggest that RGF thickness is influenced by JE, but is unaffected by disc position and configuration.

A novel motif governs APC-dependent degradation of Drosophila ORC1 in vivo

Regulated degradation plays a key role in setting the level of many factors that govern cell cycle progression. In Drosophila, the largest subunit of the origin recognition complex protein 1 (ORC1) is degraded at the end of M phase and throughout much of G1 by anaphase-promoting complexes (APC) activated by Fzr/Cdh1. We show here that none of the previously identified APC motifs targets ORC1 for degradation. Instead, a novel sequence, the O-box, is necessary and sufficient to direct Fzr/Cdh1-dependent polyubiquitylation in vitro and degradation in vivo. The O-box is similar to but distinct from the well characterized D-box. Finally, we show that O-box motifs in two other proteins, Drosophila Abnormal Spindle and Schizosaccharomyces pombe Cut2, contribute to Cdh1-dependent polyubiquitylation in vitro, suggesting that the O-box may mediate degradation of a variety of cell cycle factors.

Gas phase detection of cyclic B3: 2 2E′←X 2A1′ electronic origin band

The rotationally resolved origin band in the 2(2)E'<--X2A1' electronic spectrum of cyclic B3 has been observed by cavity ring down spectroscopy in the gas phase. The B3 molecule was generated in a supersonic planar plasma containing decaborane (B10H14) and neon as a carrier gas. The rotational structure pattern is that of a cyclic molecule. It is analyzed assuming an equilateral triangle in both electronic states. The band origin is determined to be 21 853.52 cm(-1), and the bond lengths 1.603 77(106) A in the ground and 1.619 07(96) A in the excited electronic state are inferred from analysis of the rotational structure.

Degradation of origin recognition complex large subunit by the anaphase-promoting complex in Drosophila

The initiation of DNA synthesis is thought to occur at sites bound by a heteromeric origin recognition complex (ORC). Previously, we have shown that in Drosophila, the level of the large subunit, ORC1, is modulated during cell cycle progression and that changes in ORC1 concentration alter origin utilization during development. Here, we investigate the mechanisms underlying cell cycle-dependent degradation of ORC1. We show that signals in the non-conserved N-terminal domain of ORC1 mediate its degradation upon exit from mitosis and in G1 phase by the anaphase-promoting complex (APC) in vivo. Degradation appears to be the result of direct action of the APC, as the N-terminal domain is ubiquitylated by purified APC in vitro. This regulated proteolysis is potent, sufficient to generate a normal temporal distribution of protein even when transcription of ORC1 is driven by strong constitutive promoters. These observations suggest that in Drosophila, ORC1 regulates origin utilization much as does Cdc6 in budding yeast.

Genetic diversity of nuclear and mitochondrial genomes in Pinus parviflora Sieb. & Zucc. (Pinaceae) populations

Genetic diversities of the nuclear and mitochondrial genomes in Pinus parviflora were studied in 16 populations, which were distributed across most of the species' range in Japan. Six mitochondrial DNA haplotypes were identified among the 16 populations. The intrapopulation diversity of allozymes was similar to that of other endemic woody species (H(S)=0.259). Although P. parviflora is distributed in discrete populations, differentiation between these was very low (G(ST)=0.044). In addition, the extent of genetic differentiation between two varieties (var. pentaphylla and var. parviflora) was extremely low (G(VT)=0.001). Intrapopulation diversity of mitochondrial DNA was also very low (H(S)=0.098), but population differentiation was high (G(ST)=0.863). Moreover, the distribution of haplotypes reflected the taxonomic differences between P. parviflora var. pentaphylla and var. parviflora. The populations of var. pentaphylla and var. parviflora contained different haplotypes. Differing modes of inheritance may account for the differences in nuclear and mitochondrial genetic diversity.

Expression mechanism of the allosteric interactions in a ribozyme catalysis

The contribution of substrate binding to cooperative regulation in the rate process of ribozyme catalysis has been investigated using allosteric ribozymes. The high sensitivity to the substrate lengths is attributed to the catalytic core folding which proceeds due to the energetic contribution of the substrate binding. One role of the effector (FMN) is the promotion of the core folding through the stabilization of the aptamer domain. Another role is the inhibition of the cleavage chemistry by perturbing the intermediate state in the rate process. The total effects of these two types of kinetic regulation determine the substrate dependency of the cooperative interaction on the catalytic reaction. An adequate correlation between the type of regulation and the substrate binding is responsible for the cooperative interaction in the kinetic process.

Direct chemically mediated synaptic transmission from mechanosensory afferents contributes to habituation of crayfish lateral giant escape reaction

The neural mechanism of habituation of the crayfish lateral giant-mediated escape reaction was analyzed electrophysiologically and pharmacologically. Upon repeated stimulation of tailfan afferents (at 0.2-1 Hz) lateral giant showed rapid habituation and failed to spike. Upon low-intensity sensory stimulation, the lateral giant responded with two subthreshold excitatory post-synaptic potentials, the alpha and beta components. A third component, the alpha' component, was discriminated at the boundary of excitatory post-synaptic potentials between the late alpha and early beta components with stimulation just subthreshold or suprathreshold to evoke lateral giant spikes. This alpha' component increased in amplitude with hyperpolarizing current injected into the lateral giants, although the amplitude of both the alpha and beta components remained constant. Furthermore, bath application of the nicotinic antagonist, d-tubocurarine caused a rapid reduction in the amplitude of the alpha' component while the amplitude of the beta component was reduced gradually and that of the alpha component remained unchanged. Single-hair stimulation indicated that some sensory afferents made direct connections with the lateral giants mediated by chemical synapses and form the potential of alpha' component of the lateral giants. Since lateral giant inactivation was associated with a reduction of excitatory post-synaptic potential amplitude of the alpha' component, connection from these afferents could contribute, at least in part, to lateral giant habituation.

Enhancement of mitochondrial oxidative stress and up-regulation of antioxidant protein peroxiredoxin III/SP-22 in the mitochondria of human pre-eclamptic placentae

A growing body of evidence indicates that the pathogenesis of pre-eclampsia is closely associated with oxidative stress occurring in mitochondria. In the present study, we evaluated the degree of mitochondrial lipid peroxidation by assessing the accumulation of 4-hydroxy-2-nonenal (HNE)-modified proteins and examined the expression of mitochondrial antioxidant protein peroxiredoxin III/SP-22 in normal and pre-eclamptic human placentae. The accumulation of HNE-modified proteins increased to a greater extent in both the mitochondria and cytosol of pre-eclamptic placentae than in those of normal placentae. Moreover, the accumulation of HNE-modified proteins was much more evident in the mitochondria than in the cytosol, indicating that lipid peroxidation occurred mainly in the mitochondria of pre-eclamptic placentae. The mRNA expression of peroxiredoxin III/SP-22 was increased about 2-fold in pre-eclamptic placentae compared to normal placentae. The protein levels of peroxiredoxin III/SP-22 were approximately 4-fold higher in pre-eclamptic placentae than in normal placentae. Immunohistochemistry of placental tissues showed that the levels of peroxiredoxin III/SP-22 protein were increased in the trophoblasts of floating villi, stromal cells of stem villi, and decidual cells in pre-eclamptic placentae. These results indicate that peroxiredoxin III/SP-22 plays a crucial role in the protection of placental function from oxidative stress occurring in mitochondria of pre-eclamptic placentae.