Influence of hyperbaric environment on physiological tremor

The effect of pressured environment from 1 to 24 ATA (Atmosphere Absolute) on total power spectrum (TP) of physiological tremor, whose value was the sum of power spectra for frequency range in 0.5-50 Hz, was investigated. The main effects obtained were as follows. (1) In the case of 3 ATA, TP during the pressure holding period denoted a similar value as the value in 1 ATA. In the latter half of the period, the TP increased. When the pressured environment is 4 ATA, in which the partial pressure of the nitrogen gas was 3.6 ATA, the TP decreased during the pressure holding period compared with the value in 1 ATA. Nitrogen narcosis was recognized at the partial pressure of 3.6 ATA, thus the effect denoted a decrease of TP. (2) In the cases of 16 and 19 ATA using heliox gas, during the pressure holding period, TP decreased compared with the value in 1 ATA, but in the case of 24 ATA the value increased. The partial pressure of helium gas of 23.6 ATA indicated a high pressure nervous syndrome, therefore, the influence of high pressure on TP was recognized as one of the causes of the increase of TP. (3) The influence of inhibitors of the autonomic nervous system on TP during the pressure holding period of 3 ATA was recognized. After intake of the inhibitor for the parasympathetic nerve (atropine) during the pressure period, TP increased, while for the intake of the inhibitor for the sympathetic nerve (propanol), TP decreased.     

Solitary fibrous tumor of the fourth ventricle: case report

A rare case of solitary fibrous tumor, located wholly within the fourth ventricle, is reported. A 57-year-old male presented with headache and nausea. The preoperative magnetic resonance images revealed a well circumscribed mass in the fourth ventricle that exhibited a low intensity on T1-weighted images and homogeneously enhanced with gadolinium. Vertebral angiogram revealed a tumor stain supplied from the choroidal branches of the posterior inferior cerebellar artery. The tumor was totally resected through a midline suboccipital approach. Histologically, the tumor was composed of spindle-shaped cells growing in fascicles within a collagenous matrix. Immunohistochemical staining demonstrated vimentin and the CD34 positivity of tumor cells. Solitary fibrous tumor is a newly described entity, which should be considered in the differential diagnosis for dural-based lesions.     

Effect of hyperprolactinemia induced by pituitary grafts or castration on porphyrin content of the mouse Harderian gland

The histology and porphyrin concentrations of Harderian glands and plasma prolactin levels were examined in B6C3F1 mice castrated or isografted with pituitaries in combination with the administration of bromocriptine (2-bromo-á-ergocryptine), a potent suppressor of prolactin. Four pituitaries were transplanted underneath the bilateral kidney capsules of each mouse. Furthermore, we investigated Harderian porphyrins and plasma testosterone levels in mice that were castrated or treated with neuroleptic butyrophenone (timiperone), a potent accelerator of prolactin, and treated concurrently with bromocriptine. Light microscopically, pituitary grafts increased the concretion of porphyrin pigments within the Harderian gland lumina. Pituitary grafts or castration increased both Harderian porphyrin concentrations and plasma prolactin levels compared with the intact control mice. In pituitary-grafted or castrated mice, bromocriptine distinctly prevented the rise in both porphyrins and prolactin levels. Administration of butyrophenone did not result in any marked change in testosterone levels, although Harderian gland porphyrins were significantly increased. The present results indicate that in mice prolactin stimulates the porphyrin production of the Harderian gland and has an important role in the regulation of Harderian gland porphyrins.     

Experimental and numerical predictions of the ultimate strength of a low-cost composite transtibial prosthesis

Saito et al. (Modern Plastics 1997;74:175-7) have developed a low-cost transtibial prosthesis made of fiber-reinforced plastic (FRP). The prosthesis is comprised of an aluminum pylon, a cosmetic cover, and a constant cross-section composite foot into which aluminum supports are screwed to increase load-bearing capacity. Replacing these supports with a single integrated FRP stiffener significantly reduced manufacturing cost while providing high strength, great durability, and smooth walking. The optimal location and orientation of the proposed FRP stiffener were determined by finite element (FE) analysis. When a replica of this component was tested according to ISO standard 10328, the experimental prosthesis catastrophically failed under 6,600 N of force. Maximum percent error of strain between experimental and numerical results was 18.6%, showing good correlation between the two data sets. The optimized design provides sufficient strength and reduces the cost of manufacturing and thus can be used to replace the original design.     

Inhibition of ATM and ATR kinase activities by the radiosensitizing agent, caffeine.

Caffeine exposure sensitizes tumor cells to ionizing radiation and other genotoxic agents. The radiosensitizing effects of caffeine are associated with the disruption of multiple DNA damage-responsive cell cycle checkpoints. The similarity of these checkpoint defects to those seen in ataxia-telangiectasia (A-T) suggested that caffeine might inhibit one or more components in an A-T mutated (ATM)-dependent checkpoint pathway in DNA-damaged cells. We now show that caffeine inhibits the catalytic activity of both ATM and the related kinase, ATM and Rad3-related (ATR), at drug concentrations similar to those that induce radiosensitization. Moreover, like ATM-deficient cells, caffeine-treated A549 lung carcinoma cells irradiated in G2 fail to arrest progression into mitosis, and S-phase-irradiated cells exhibit radioresistant DNA synthesis. Similar concentrations of caffeine also inhibit gamma- and UV radiation-induced phosphorylation of p53 on Ser15, a modification that may be directly mediated by the ATM and ATR kinases. DNA-dependent protein kinase, another ATM-related protein involved in DNA damage repair, was resistant to the inhibitory effects of caffeine. Likewise, the catalytic activity of the G2 checkpoint kinase, hChk1, was only marginally suppressed by caffeine but was inhibited potently by the structurally distinct radiosensitizer, UCN-01. These data suggest that the radiosensitizing effects of caffeine are related to inhibition of the protein kinase activities of ATM and ATR and that both proteins are relevant targets for the development of novel anticancer agents.     

Infantile T cell acute lymphoblastic leukemia complicated by thrombotic microangiopathy and human herpes virus 6 infection after allogeneic peripheral blood stem cell transplantation using CD34-positive cells]

We report on a 19-month-old boy with refractory T-cell acute lymphoblastic leukemia who underwent allogeneic peripheral blood stem cell transplantation using positively selected CD34 cells from his HLA two-loci mismatched mother. The conditioning regimen consisted of busulfan (140 mg/m2/d for 2 days), total body irradiation (12 Gy) and melphalan (210 mg/m2). The patient received cyclosporin A for graft-versus-host disease (GVHD) prophylaxis. The CD34-positive cells were separated using an immunomagnetic cell-separation system (Isolex 50). The number of infused CD34-positive cells was 4.4 x 10(6)/kg. Successful engraftment was confirmed on day 14 by fluorescent in situ hybridization of X chromosomes. The patient experienced severe diarrhea due to thrombotic microangiopathy (TMA) following acute GVHD, and died on day 71 of human herpes virus type 6 pneumonitis. Stem cell transplantation using CD34 positively selected cells from HLA-mismatched related donors may be a useful treatment with low incidence of severe GVHD, but many problems remain to be overcome, including severe viral infections and TMA.