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Get PDFEffects of ATP on the intracellular free calcium ion concentration ([Ca2+]i) in the rabbit eye suprachoroid were investigated by means of fura-2 microfluorophotometry. ATP application (10 to 100 µM) elicited a dose-dependent biphasic [Ca2+]i-increase: a fast phase typically peaking within 30 s and a following slow plateau phase, which lasted during the presence of ATP. The slow plateau phase was markedly diminished by removal of extracellular Ca2+, whereas the fast phase remained. An inhibitor of Ca2+ release from the sarcoplasmic reticulum (TMB-8), an endoplasmic Ca2+-ATPase inhibitor (thapsigargin) and a phospholipase C (PLC) inhibitor (U-73122) diminished the fast phase. A P2 receptor antagonist (Suramin) inhibited the ATP-induced [Ca2+]i-response. The potency order of ATP and related substances in producing the [Ca2+]i-elevation was UTP≅ATP>ATP-γ-S>ITP>ADP. β,γ-MethyleneATP, 2-methylthioATP and UDP evoked no response. This order is consistent with the P2Y2 receptor characteristics. Cross-desensitization between ATP and UTP excludes the co-existence of the other types of receptors. In conclusion, the ATP-induced [Ca2+]i-elevation in the rabbit eye suprachoroid was elicited by the Ca2+ release from the PLC-dependent, thapsigargin-sensitive intracellular Ca2+ storage sites by activating P2Y2 nucleotide receptors.departmental bulletin pape
Get PDFA morphological filter and pipeline analysis was applied to computed radiographs (CR) to abstract the geometrical characteristics of the trabecular pattern and to analyze bone mechanical properties. By applying a morphological filter to the CR images, trabecular patterns were divided into 8 subset groups (n=0 through 7) by the trabecular thickness. Sumset images were also derived from the thicker trabeculae group (n=2-5, 3-6, and 4-7) to examine the criteria relating the percentage of thicker trabeculae to the strength of the bone. A method to analyze the bone mechanical properties was developed, based on the hypothesis that data of connective line segments were loaded mechanically. By this method, trabeculae were analyzed in the fifth lumbar vertebrae from etidronic acidtreated and non-treated ovariectomized osteoporosis rat models, and in human third lumbar vertebrae. Consequently, it was shown that total loss of bone mass accompanied a reduction of consecutive trabecular number in the rat osteoporosis model, especially in parts of the bone having thick trabeculae. The reduction in number of connective trabeculae, from one cortical side to the other, occurred at a similar rate, along both the craniocaudal and anteroposterior axes in the vertebral bodies of the experimental osteoporosis rats. In the dynamic study with human third vertebral blocks, no significant correlation was observed between the bone mineral density of the bone specimens and their ultimate strength (R2=0.093). In contrast, the abstracted percentage of thicker trabeculae, derived from the sumset (n=2-5) images, showed a strong correlation with bony mechanical properties (Young's modulus: R2=0.915, maximum point load: R2=0.815). The result calculated by this methodology can serve as an excellent index to indicate bone strength under non-destructive, living conditions.departmental bulletin pape
Get PDFIn Ghana, West Africa, the prevalence of dual HIV-1 and HIV-2 infections remains to be clarified, and HIV viral load measurement is yet to be established. Conventional assays for HIV-1 RNA measurements have been limited specifically to HIV-1 subtype B, preventing their utilization for Ghana where HIV-1 subtypes A, D and G are prevalent. Therefore, we set out to distinguish the types of HIV infection existing in Ghana so as to determine the extent of actual dual infections, and to measure plasma HIV-1 RNA. Blood samples were collected from 563 sick and healthy Ghanaians who visited hospitals in 1996 and 1997. After T cells were counted, HIV antibody was screened and confirmed by six different commercial assays and one in-house test. Nested PCR was then used to verify HIV-1 and HIV-2 presence by type-specific primers. Plasma HIV-1 RNA was measured by an improved commercial RT-PCR assay, sensitive to all HIV-1 group M subtypes. HIV-1 alone (89%) clearly dominated over HIV-2 alone (2%), and HIV-1 and HIV-2 dual infections were found in 9%. Valid viral load measurements were obtained on test plasma representing the main HIV-1 subtype (A) prevailing in Ghana. A high amount of HIV-1 RNA (5.9 mean log10 RNA copies/ml) was observed in the typical stages of HIV infection represented by groups of CD4+ cell counts. We have clarified the seroprevalence of HIV-1 and HIV-2 amongst HIV seropositives, and the high viral load of HIV-1 reflects its influence on AIDS in Ghana.departmental bulletin pape
Get PDFThe periodontal ligament (PDL) functions under constant mechanical stress, and PDL cells obviously control PDL functions under such conditions. We have previously found that the mRNA expression of the Ca2+-binding protein S100A4 and β-actin is higher in the PDL from erupted teeth than in the PDL from teeth under eruption. This suggested a role for S100A4 in the response of PDL cells to mechanical stress, possibly by coupling Ca2+ and the cytoskeletal system. In the present study, we investigated the direct effects of cyclical stretching on the mRNA expression of S100A4 and two cytoskeletal components (β-actin and α-tubulin) by PDL cells. In Northern blotting analysis, the expression of S100A4, β-actin, and α-tubulin mRNAs was higher in the PDL from fully erupted and functional bovine teeth than in partially erupted ones. Similarly, when bovine PDL cells were mechanically stimulated by means of the Flexercell Strain Unit, the expression of S100A4，β-actin, and α-tubulin mRNAs increased over the control levels. The results of our present study indicate that S100A4 is involved in the responses of PDL cells to mechanical stress possibly by coupling Ca2+ to the cytoskeletal system in these cells.departmental bulletin pape
Get PDFTo study the involvement of the Herpes simplex virus type 1 (HSV-1) in patients with Behçet's disease (BD), PCR was used to detect HSV-1 DNA and RNA (LAT, TK, gB) in peripheral blood leukocytes and oral smears from patients with BD. Out of 32 patients with BD and 30 healthy volunteers, HSV-1 specific DNA was not detected in any case. Using a highly sensitive competitive RT-PCR method, HSV-1 specific mRNA was not detected either inperipheral blood leukocytes from any of the patients or volunteers. In contrast, serum levels of IgG anti HSV-1 antibody were higher in patients with BD; however, there were 70% sero-positives among the control subjects. Even though it has been reported that the highly frequent presence of the HSV-1 genome in peripheral blood is a characteristic feature of BD, our results show that the HSV-1 genome and its expression are not present in peripheral blood in patients with BD. We could not find any evidence that the lesions associated with BD were caused by the direct lytic effects of HSV-1.departmental bulletin pape
Get PDFWe report a series of 13 consecutive patients with intracranial abscess treated at our institution since examination by computed tomography (CT) became available. After various treatments, all abscesses healed. CT has broadened the range of treatment options. Manual puncture was performed in most patients. Stereotactic aspiration through a burr hole, medical therapy alone, or complete excision, including the capsule, via craniotomy may be chosen in cases selected by CT analysis. Individualization of treatment in this disease has become increasingly valuable in effecting a cure.departmental bulletin pape
Get PDFCortical neurons develop into neuronal death four days after transient cerebral ischemia. The aim of this study is to detect early post-ischemic changes in the cortex that will develop into cortical neuronal death later. The detection is important for starting adequate treatment within the therapeutic window. We have examined changes in middle-latency auditory evoked potentials (MAEPs) and cortical blood flow (CBF) in relation to the histological changes in the auditory cortex of Mongolian gerbils subjected to transient cerebral ischemia. At 2 min after bilateral carotid occlusion, the amplitude of MAEPs and CBF were reduced to 22.2 to 23.4% and 24.3 to 27.4% of the pre-ischemic level, respectively. In the 4-min ischemia group, the amplitude of each parameter recovered rapidly to the pre-ischemic level. In the 12-min ischemia group, the recovery of MAEPs and CBF was delayed by, from 20 to 30 min, and about 10 min, respectively. Also, scattered eosinophilic neurons were observed in the auditory cortex, and a mild but significant decrease in the number of surviving neurons was also detectable. The recovery of MAEPs in both groups was characterized by the appearance of a transient high amplitude (2.67 ± 0.6 µV) low frequency (62.2 ± 3.4Hz) wave. The present findings show that cortical neuronal death in the auditory cortex, which results from transient cerebral ischemia in the gerbil, is predictable by detecting the delay in the recovery of MAEPs amplitude and CBF during the very early post-ischemic phase. Clinical data is mandatory for the application of the presented method in clinical cases to save many patients with acute cerebrovascular diseases in the future.departmental bulletin pape
Get PDFThe purpose of this investigation was to compare the dynamic viscoelastic properties of various models composed of denture teeth and heatcured denture base resin. The specimens were porcelain and resin teeth mounted in denture base resin. Compressive dynamic stiffness and phase differences were measured with a viscoelasticspectrometer. Measurements of the viscoelastic frequency spectrum based on the fast Fourier transform of displacement to applied random forces were analyzed with a spectrum analyzer. The stiffness of the specimens was independent of the frequency. The stiffness of the porcelain specimens was higher than that of the resin ones measured under the same conditions. The phase lag of the specimens was dependent on the frequency. The phase lag of the porcelain specimens was lower than that of the resin ones measured under the same conditions. This study suggested that the acrylic resin teeth had greater toughness and higher shock-absorbing ability than the porcelain teeth, and that the porcelain teeth were more brittle than the acrylic resin ones, whether the teeth were isolated or in dentures.departmental bulletin pape
Get PDFOxidative DNA damage has been implicated in a variety of pathophysiological processes especially cancer and aging. Therefore, considerable interest has recently been given to the chemical structure and repair mechanisms of the damaged sites. In examining types of novel oxidative DNA damage, our group recently found that 2-aminoimida-zolone (Iz) is formed in amounts larger than that of 8-oxo-G during the photoreaction of DNA with riboflavin. Our group also pointed out the intriguing possibility that the Iz thus formed can produce a stable base pair with C, thereby giving rise to a G:C to C:G transversion mutation. In this short review, we focused on the new type of oxidative DNA damage, Iz.departmental bulletin pape
Get PDFThe athletic mouthguard has been used for the prevention of orofacial injuries in contact sports. In this research, the effectiveness of a mouthguard was evaluated for its protection of the maxillary teeth of a human dry skull through experimental modal analysis. The upper central incisor was excited by an electrodynamic shaker. The frequency response functions of the upper teeth were then recorded on an FFT analyzer in order to identify modal shapes of the maxillary arch with and without a mouthguard. In addition, transient response simulations were carried out and decay rates of transient response waves were compared. As a result, when the mouthguard was in place, the resonance peaks of the frequency response functions were dampened, and the nodes of the modal shapes for the anterior teeth were indefinite in the frequency domain over 1 kHz. In the transient response simulation, the decay rates of transient response waves when the mouthguard was used were significantly higher than those when the mouthguard was not used (p<0.01). The results suggest that the mouthguard relieves the stress concentrated on the anterior teeth in a frontal collision by absorbing and dispersing some of the shock energy, thus quickly stopping the vibration of the maxillary teeth. These findings support the clinical fact that mouthguards prevent orofacial injuries in sporting activities.departmental bulletin pape