Molecular analysis of the genome segments S1, S4, S6, S7 and S12 of a Rice gall dwarf virus isolate from Thailand; completion of the genomic sequence.

The complete nucleotide sequences of the double-stranded RNA segments S1, S4, S6, S7 and S12 of the genome of a Rice gall dwarf virus (RGDV) isolate from Thailand were determined. The segments consisted of 4505, 2622, 1648, 1652 and 853 nucleotides, encoding putative proteins of 1458, 725, 489, 511 and 206 amino acids with molecular masses of approximately 166, 80, 53, 59 and 24 kDa, respectively. Homology searches indicated that each of the putative proteins has a counterpart in isolates of Rice dwarf virus (RDV) and Wound tumor virus, two other species in the genus Phytoreovirus. However, no similarities were found to other registered sequences, including those of other viruses that belong to the family Reoviridae. The identities between homologous structural proteins of RGDV and RDV ranged from 34 to 51% and were thus higher than those between homologous non-structural proteins of RGDV and RDV (16-37%). Among the nonstructural proteins, the highest amino acid sequence identity (37%) was observed for RGDV Pns11 and RDV Pns10, a constituent of tubular inclusions. This observation suggests that a specific amino acid backbone might be required for maintaining not only the three-dimensional structure of virions but also that of inclusions. The entire sequence of the RGDV genome is now available.

Non-selective retention of PSP toxins by the mussel Mytilus galloprovincialis fed with the toxic dinoflagellate Alexandrium tamarense.

Mussels, Mytilus galloprovincialis, were contaminated by paralytic shellfish poisoning (PSP) toxins by being fed with the toxic dinoflagellate Alexandrium tamarense. Temporal variations in the toxin content and the profile of mussels during the feeding experiment were monitored by high-performance liquid chromatography (HPLC). The toxin profile of mussels was compared with that of A. tamarense to clarify the mechanism of uptake of toxins in mussels. The prominent toxins in mussels and A. tamarense were N-sulfocarbamoyl toxins (C1,2) and carbamate toxins, gonyautoxin-1,4 (GTX1,4). The toxin profiles of both mussels and A. tamarense were almost constant throughout the experimental period. There were no remarkable differences in the toxin proportion between mussel and A. tamarense. These results indicate that mussels do not selectively accumulate particular toxins.

The growth and cyst formation of a toxic dinoflagellate, Alexandrium tamarense, at low water temperatures in northeastern Japan.

A field survey was carried out in early spring to investigate the growth physiology and efficiency of cyst formation of Alexandrium tamarense in low water temperatures. A bloom of A. tamarense occurred in a stratified water column, formed by river inflow. The in situ growth rate estimated from daily cell abundance was high, 0.33 divisions day(-1), at 7.5-9 degrees C. New cysts began to be observed during the late growth phase. Maximum cyst flux (600 cysts cm(-2) day(-1)) was observed just after maximum cell abundance occurred. PO(4)-P Chl a(-1) gradually decreased and reached extremely low levels beyond the mid-growth phase of A. tamarense. As sinking cysts were also recognized at that time, it suggests cyst formation may have been induced by depletion of phosphorus source. The incidence of cyst formation (C.I) was 30%. The number of C.I was the same as reported previously for batch cultures under conditions suitable for vegetative growth. These results indicate that A. tamarense grows with considerably higher growth rate and transforms to cysts in high numbers, in low water temperatures in the field.

Production of monoclonal antibody against Scrippsiella trochoidea cysts and its application to analysis during cyst formation and enzyme-linked immunosorbent assay.

A monoclonal antibody was produced by the fusion of mouse myeloma cells with spleen cells from a mouse immunized with the cysts of Scrippsiella trochoidea, marine phytoplankton. Immunofluorescence microscopic observation showed that the antibody reacted with the spines on the cyst but not with the vegetative cells and cyst walls. An enzyme-linked immunosorbent assay could be used to measure the cysts in muddy bottom sediments using the purified antibody conjugated with horseradish peroxidase.

Molecular analysis of ribosomal RNA gene of red tide algae obtained from the seto inland sea.

Eleven clones from five species of the planktonic microalgae, (Chattonella antiqua, Chattonella marina, Heterosigma akashiwo, Alexandrium catenella, and Scrippsiella trochoidea), which were collected from the Seto Inland Sea in Japan and from Thailand, were subjected to nucleotide sequence analysis of the D1/D2 domain of the large subunit (LSU) of their ribosomal RNA genes. After amplification by polymerase chain reaction using degenerated primers, whole-nucleotide sequences for the D1/D2 domains of the LSU rRNA gene of 11 microalgae were analyzed. Phylogenic tree analysis using these nucleotide sequences showed each species located in a cluster corresponding to its morphological classification. The nucleotide sequence data for Chattonella spp. suggest that multiple clones of both Chattonella antiqua and Chattonella marina are present in the Seto Inland Sea and that red tide blooms of Chattonella spp. in different years may have contained different clones.

Cerebral blood flow regulation under activation of the primary somatosensory cortex during electrical stimulation of the forearm.

Coupling of neuronal activity to cerebral blood flow (CBF) is widely accepted, but the exact mechanism is still under investigation. We assessed the responses of CBF coupled with electrical activity over the primary somatosensory cortex (S-I) during electrical stimulation of the contralateral forearm in cats. CBF in S-I was monitored using laser-Doppler flowmetry (LDF), and electrical activity was recorded with a tungsten microelectrode. The effects of varying stimulus intensity and frequency were examined to assess the optimal stimulation parameters. CBF increased within 10 sec after onset of stimulation, sustained the plateau level, and returned to the pre-stimulus level after cessation of stimulation. The maximum response was obtained at 4 Hz under a constant intensity. Optimal stimulus intensity at 4 Hz ranged from 8 to 10 V. At intensity higher than 10 V, CBF increases reached a near-plateau level, while mean arterial blood pressure (MABP) decreased slightly. Electrical activity was recorded at the same restricted area where CBF increased. Low frequency components of the power spectrum of electrical activity increased as the CBF increase became greater. A tight coupling of CBF increases to neuronal activation is suggested, and CBF regulation may be affected by stimulation parameters.

Abducens nerve neurinoma--case report.

A 61-year-old female presented with an abducens nerve neurinoma manifesting as diplopia and facial numbness. The tumor was totally removed, and the exact origin was confirmed intraoperatively. Neuroradiological imaging and clinical history are frequently insufficient to obtain an accurate preoperative diagnosis of intracranial neurinoma.

The minor outer capsid protein P2 of rice gall dwarf virus has a primary structure conserved with, yet is chemically dissimilar to, rice dwarf virus P2, a protein associated with virus infectivity.

The nucleotide sequence of the genome segment 2 (S2) of rice gall dwarf virus (RGDV), a phytoreovirus, when compared with the amino acid sequence of a component protein of the virus, showed that S2 potentially encoded a 127K minor outer capsid protein. This 127K protein designated as P2 and the 127K minor outer capsid protein (also termed P2) of rice dwarf virus (RDV) are similar in size, located in the outer capsid, and have well-conserved predicted polypeptide sequences, suggesting similar functions. Infectivity to insect vector cell monolayers of RGDV was maintained and the P2 protein was retained irrespective of carbon tetrachloride (CCl4) treatment. This is in contrast to the infectivity of RDV which is removed along with P2 protein following CCl4 treatment. RGDV with P2 was acquired by vector insects and transmitted to host plants, although RDV lacking P2 could not be transmitted to plants as previously published. These results imply that RDV and RGDV require P2 proteins for virus infectivity to vector insects.

Effect of glycerol on blood flow distribution in tumoral and peritumoral brain tissue.

To evaluate the effect of glycerol, thirty-two patients with brain tumor were directed to the study, including 17 gliomas and 15 meningiomas. Blood flow before and after the administration of glycerol were measured with Xe CT. Glioma was significantly hypo-perfused. The peritumoral edema of glioma and meningioma were also hypo-perfused. On the other hand, Meningioma was significantly hyper-perfused. After the administration of glycerol, blood flows were increased except for glioma. We suggested that, vascular responses to glycerol was different in the two tumor types. The steal phenomena of blood flow might occur in glioma.

Assessment of vasoreactivity in brain edema by acetazolamide activation SPECT and PET.

Our study was performed to find out cerebrovascular reactivity post acetazolamide administration in patients with peritumoral edema. Adult patients (n = 9) underwent CBF measurement by 99mTc-HMPAO SPECT pre and post 1 gram i.v. acetazolamide. In all patients, this procedure was repeated once again within 10 days of performing tumor removal. Five of these patients also underwent CBF measurement pre and post 1 gram i.v. acetazolamide post surgery only using oxygen-15 labeled H2O PET. Asymmetry index (AI) was calculated as ratio of ROI counts in the peritumoral edematous area and symmetrical ROI on the contralateral normal hemisphere. The AI increased after acetazolamide in edematous gray matter post operatively though the resting AI remained almost same post operatively. AI in edematous white matter showed non-significant increase post operatively both at rest and after acetazolamide. Good linear correlation of AI between PET and SPECT was observed both in gray and white matter. The improvement of vascular reactivity in edematous gray matter after tumor removal suggests that mass effect not only reduces CBF but also suppresses vascular reactivity. White matter vascular reactivity in early post operative period is little improved, possibly due to factors other than mass effect i.e. excess water accumulation in white matter perivascular space.

Induction of matrix metalloproteinases following brain injury in rats.

Matrix metalloproteinases (MMPs) are important in various pathophysiological processes related with the tissue remodeling. We planned the experiments to determine whether MMPs participate in disruption and repair of the tissue following brain injury. We have studied induction of MMP-9, a 92 kilodalton (kDa) gelatinase, in traumatic brain tissue, which may be produced by brain residual cells. We speculate that MMP-9 plays a role in post-traumatic brain edema formation.

Responses of cerebral blood flow regulation to activation of the primary somatosensory cortex during electrical stimulation of the forearm.

We assessed the cerebral blood flow (CBF) response to electrical stimulation of the contralateral forearm over the primary somatosensory cortex (S-I) in anesthetized cats. CBF was monitored continuously using laser-Doppler flowmetry (LDF). In the first set of experiments, the effects of varying stimulus frequency and intensity were examined. During stimulation, CBF in S-I was increased significantly. At high stimulus intensity, response reached a near-plateau level. In the second set of experiments, the CBF response after introduction of an intracerebral mass was investigated using a mechanical microballoon model to simulate an intracerebral hematoma. A microballoon was inserted into the ventral posterolateral nucleus of the thalamus (VPL). Following gradual balloon inflation, there was a rapid reduction in CBF response. We conclude that CBF regulation to neuronal activation is affected by stimulation parameters, and is impaired by an intracerebral mass obstructing the afferent sensory pathway.

[Hyperthermia of metastatic brain tumor with implant heating system: a preliminary clinical results].

Metastatic brain tumors were treated by interstitial hyperthermia with an Implant Heating System, which consists of three major parts: ferromagnetic implant (thermoseed), generator of high frequency (240 KHz) and induction coil (30 cm in diameter). The implant is made of Fe-Pt alloy, 1.8 mm in diameter and 15 to 20 mm in length, whose Curie point is 68 - 69 degrees C. Seven cases of metastatic brain tumor, 5 from lung cancer, one from breast cancer and another from colon cancer, were involved in this study. One or several implants were placed inside the tumor by CT guided stereotaxis, or manually inserted at craniotomy. Interstitial hyperthermia at 44 - 46 degrees C was made by IHS for 30 to 60 minutes twice or three times a week. External irradiation was simultaneously combined with hyperthermia in 6 cases. Repeated, longterm hyperthermia (8 - 45 times) was possible in all cases except one, whose treatment was discontinued due to migration of the implant. No other serious side effect was found in any cases during and after the treatment. Repeated CT scans reveal complete response in 2, minor response in one and progression in 3 cases. Therefore this preliminary clinical study indicates that interstitial hyperthermia with IHS is very useful and promising method for treating intracranial metastases.

[Brain abscess following cerebral infarction: a case report].

The authors report a case of brain abscess following cerebral infarction. A 73-year-old man was admitted to our clinic with symptoms of right hemiparesis and total aphasia. CT scan revealed abnormal low density area in the left fronto-temporo-parietal region. Cerebral angiography demonstrated occlusion of the left middle cerebral artery at the M1 portion. On the 16th hospital day, an episode of generalized seizure with high fever appeared, and intermittent high fever persisted thereafter. Two months after admission, CT scan revealed several cystic lesions with marked ring enhancement at the site of cerebral infarction, suggesting multiple abscesses. Aspirations of left frontal and parietal abscesses were accomplished and the cultures of the pus disclosed Proteus vulgaris. Due to progressive hydrocephalus, a ventriculoperitoneal shunt was constructed one month later. Repeated CT scans showed a gradual diminution of the abscesses. It is considered that the blood-brain barrier is broken and the local immunological system against bacteria may be weakened when the brain is damaged by ischemia. Brain abscess seems to be developed in such circumstances even under the influence of transient bacteremia which originates in other parts of the body. Therefore the possibility of cerebral abscess should be suspected if patients with cerebral infarction suffer from the symptoms such as fever, neck stiffness or disturbance of consciousness.