Putative channel components for the fast-rotating sodium-driven flagellar motor of a marine bacterium

The polar flagellum of Vibrio alginolyticus rotates remarkably fast (up to 1,700 revolutions per second) by using a motor driven by sodium ions. Two genes, motX and motY, for the sodium-driven flagellar motor have been identified in marine bacteria, Vibrio parahaemolyticus and V. alginolyticus. They have no similarity to the genes for proton-driven motors, motA and motB, whose products constitute a proton channel. MotX was proposed to be a component of a sodium channel. Here we identified additional sodium motor genes, pomA and pomB, in V. alginolyticus. Unexpectedly, PomA and PomB have similarities to MotA and MotB, respectively, especially in the predicted transmembrane regions. These results suggest that PomA and PomB may be sodium-conducting channel components of the sodium-driven motor and that the motor part consists of the products of at least four genes, pomA, pomB, motX, and motY. Furthermore, swimming speed was controlled by the expression level of the pomA gene, suggesting that newly synthesized PomA proteins, which are components of a force-generating unit, were successively integrated into the defective motor complexes. These findings imply that Na+-driven flagellar motors may have similar structure and function as proton-driven motors, but with some interesting differences as well, and it is possible to compare and study the coupling mechanisms of the sodium and proton ion flux for the force generation.

Cloning, sequencing, and characterization of the ftsZ gene from coryneform bacteria

Taking advantage of highly conserved domains present in the ftsZ genes from Escherichia coli, Rhizobium meliloti, and Bacillus subtilis, we designed degenerate oligonucleotides (oligos) corresponding to these regions. These oligos were used as primers in PCR in order to amplify DNA sequences from Brevibacterium flavum MJ233 chromosomal DNA. The PCR product was used as a probe to recover genomic fragments from a lambda library of Br. flavum MJ233. The complete nucleotide sequence (nt) of the cloned 4.2-kb EcoRI fragment containing the ftsZ homolog from Br. flavum MJ233 indicated that the deduced gene product of the Br. flavum ftsZ homolog is composed of 438 amino acids (aa) with a deduced molecular weight of 46.9 kDa. This size of molecular weight was also confirmed by the in vitro protein synthesis assay. Comparison of this aa sequence to the corresponding sequences from E. coli, Rh. meliloti, B. subtilis, and Streptomyces coelicolor revealed a high degree of conservation and suggested that the Br. flavum ftsZ homolog has a putative GTP binding motif and a GTP hydrolizing region. Expression of Br. flavum ftsZ gene in E. coli, JM109 inhibited its cell division, leading to filamentation. This suggested that the Br. flavum ftsZ product competed with the E. coli ftsZ product.

Oxidative injury of synapse and alteration of antioxidative defense systems in rats, and its prevention by vitamin E

In order to define whether active oxygen species actually induce oxidative damage to the nervous system, and how antioxidative defense systems are changed by oxidative stress, morphological and functional changes in the nervous system and antioxidant status were investigated. When rats were exposed to 100% oxygen in a chamber, many morphological changes, e.g. swollen astrocytes around vessels, deformed nuclei in nerve cells, pigmentation, swollen mitochondria, and abnormal accumulation of synaptic vesicles in swollen nerve terminals, were observed by electron microscopy. When synaptosomes isolated from oxygen-exposed rats were stimulated by KCl, acetylcholine release from the terminal was decreased more significantly than in synaptosomes from unexposed rats (P < 0.01). Synaptic plasma membrane fluidity decreased in response to oxygen exposure, and plasma membrane permeability to sucrose was increased significantly (P < 0.05). The cholesterol/phospholipid ratio of the plasma membranes was increased by oxidative stress and the content of unsaturated fatty acids, especially arachidonic acid and docosahexaenoic acid, decreased. The levels of thiobarbituric-acid-reactive substances in the plasma membranes of oxygen-exposed rats were significantly higher than in unexposed rats (P < 0.01). These results suggest that free radicals derived from oxygen may attack nerve terminals and peroxidize the plasma membrane. It was found that in response to the oxidative stress, the status of the defense system in synapse, i.e. the concentration of vitamin E, activities of superoxide dismutase and glutathione peroxidase changed, and that many of the changes observed were reduced remarkably by the intraperitoneal administration of vitamin E prior to stress. Data support the idea that vitamin E contributes to the protection against nerve dysfunction caused by oxidative stress.

[Study of trough type audiogram of sudden hearing loss]

We investigated 974 patients with sudden sensorineural hearing loss who consulted the otolaryngological service of Hamamatsu University Hospital and four affiliated hospitals from 1984 to 1992. Among them, we selected 569 new cases showing a pure tone average of 31 dB or more at 250 Hz, 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz on the affected side in the initial audiometry performed within 14 days after the onset of sudden sensorineural hearing loss. The 569 patients consisted of 13 with acoustic neuromas (SHLANs), 493 with idiopathic sudden sensorineural hearing loss (ISHLs) and 63 others. Ten of the 13 SHLANs and 40 of the 493 ISHLs showed the trough type audiogram on the initial examination. We defined the 10 cases as the Trough AN group and the 40 as the Trough ISHL group. Statistical analysis of the difference in pure tone averages at 5 frequencies between the 2 groups demonstrated that the mean hearing losses at 125, 250 and 500 Hz of Trough AN were significantly less than those of Trough ISHL. This study demonstrates that the trough type audiogram, especially a slight low tone loss, shown in patients with sudden sensorineural hearing loss was a significant finding suggesting the presence of acoustic neuroma.

Various designs of ceramometal crown for implant restorations

The posterior design of the implant superstructure (the ceramometal crown) was classified into four categories: a ceramometal crown with an access hole on top; a cemented ceramometal crown; a ceramometal crown retained with a lingual screw; and a telescopic ceramometal crown. Cemented ceramometal crowns and telescopic ceramometal crowns are considered simpler, more esthetic, and more resistant to fracture among the four models.

Changes in lymphocyte subsets following administration of interleukin 2 and cyclophosphamide in mice with transitional cell carcinoma

We investigated the effects of combination therapy with interleukin 2(IL-2) and cyclophosphamide (CPM) in C3H/HeN mice implanted with mouse bladder tumor cells (MBT2). Tumor growth was suppressed in the mice treated with IL-2 alone and mice treated with CPM alone, although not completely. However, tumor growth was completely suppressed in the mice treated with both IL-2 and CPM. As for lymphocyte subset analysis of the spleen using flow cytometry, the frequency of Lyt2+ cells and asialo GM1+ cells was significantly higher in the mice treated with IL-2 and CPM compared to the other groups. In the lymphocyte subset analysis of the thymus, the frequency of L3T4-Lyt2+ cells was significantly lower in the mice treated with CPM alone and mice treated with IL-2 and CPM compared to the other groups.

[Isolation of enterohemorrhagic Escherichia coli (O157:H7) by an immunomagnetic separation method]

Three sporadic cases of enterohemorrhagic Escherichia coli (EHEC) O157 infection which occurred in Kanagawa in 1996 were investigated. In an attempt to determine sources of the infection, a novel method of immunomagnetic separation (IMS) was employed to isolate the bacterium from feces, foods, and other associated items. In the first case, strains of EHEC O157:H7 producing Vero toxin (VT) 2 were isolated from both feces of the patient and suspected food (cattle liver) kept at a restaurant, and the strains were found to be genotypically identical through an analysis of pulsed-field gel electrophoresis (PFGE). Subsequent investigation in the meat processing store, from which the above cattle liver had been retailed to the restaurants revealed that the store was contaminated with EHEC O157:H7 producing both VT1 and VT2. In the second case, a strain isolated from the patient was EHEC O157:H7 producing both VT1 and VT2 while strains isolated from the patient's family (without apparent symptom) and the suspected facility were O137:NM producing VT2. PFGE analysis indicated that the latter two strains were genotypically identical, suggesting that the facility thus contaminated with EHEC O157 caused the infection in question. In the third case, EHEC O157:NM producing VT2 was isolated from 4 out of 7 family members including the patient, and these strains were found to be genotypically identical by subsequent PFGE analysis. Source of the infection was, however, not determined due to lack of suspected food items. In this context, four slaughterhouses in Kanagawa Prefecture were investigated for presence of EHEC O157. As a result, strains of EHEC O157:H7 producing VT1 and VT2 were isolated from the contents of cattle's distal colon and surface of the skinned carcasses. Additional attempt was also made to determine a possibility of river water being contaminated with EHEC O157. The bacterium was, however, not isolated from water samples collected from 4 major rivers in the prefecture (at 10 collecting sites). Experiments were undertaken in order to evaluate the use of IMS in isolation of EHEC O157 from food items, with different pre-enrichment media and conditions. The results indicated that pre-enrichment by trypticase soy broth at 36 degrees C for 6 h followed by inoculating onto sorbitol MacConkey agar plate containing cefixime and tellurite was most appropriate to isolate EHEC O157 strains.

[A patient with lung metastasis of medulloblastoma]

A 15-year-old boy had metastasis to the spinal cord and then to the lung after an operation to remove a primary medulloblastoma. A medulloblastoma developed at the age of 10 years. The tumor was completely resected and the brain and spinal cord were irradiated. At the age of 13 years, metastasis to the sacral spinal cord developed and was treated with radiotherapy and intramedullary injection of methotrexate. At the age of 15 years, metastasis to the lung developed and was treated with chemotherapy (CBDCA, VP-16) followed by radiotherapy. Three months after the end of that therapy, the disease recurred but another course of radiotherapy and chemotherapy (VCR) was successful. Chemotherapy and radiotherapy were effective against metastatic lesions of medulloblastoma. With improvement in the survival rate among patients with medulloblastoma, we can expect incidence of extraneural metastases to increase. In addition to recurrence of the primary lesion and intramedullary dissemination, these metastatic lesions also require attention.

Reversibility of compound action potential during the acute phase after transitory local ischemia

We investigated the reversibility of compound action potential (CAP) changes induced after transitory local ischemia induced by rose bengal photochemically induced thrombosis of the rat anterior inferior cerebellar artery (AICA). Cochlear blood flow (CBF) was measured with a laser-Doppler flowmeter positioned on the lateral bony wall of the basal turn of the cochlea, and the CAP to an 8-kHz half-wave of sinusoid sound at 100 dB sound pressure level was monitored. The irradiation was started 5 minutes before the rose bengal administration and continued through the thrombosis formation. Tissue-type plasminogen activator (t-PA, 1 mg/kg) dissolved in saline was injected intravenously 2 minutes after complete photothrombotic blockade of the AICA in the rats presenting complete abolition of CAPs just after the vascular occlusions. Nineteen of the 51 rats presented complete abolition of the CAP just after the AICA occlusion, and the thrombosed AICA was successfully reperfused by t-PA administration in 11 of the 19 rats. The result showed that duration of ischemia was the more important determinant for the reversibility of CAPs during the acute phase (p = .00001), and the residual level of cochlear blood flow during ischemia was also an important factor (p = .066). It appeared that the critical time of ischemia for the complete recovery of CAPs was around 5 minutes, and that the critical limit for the irreversibility of CAPs within the acute phase was between 20 and 25 minutes.

A dual computed tomography linear accelerator unit for stereotactic radiation therapy: a new approach without cranially fixated stereotactic frames

PURPOSE

To perform stereotactic radiation therapy (SRT) without cranially fixated stereotactic frames, we developed a dual computed tomography (CT) linear accelerator (linac) treatment unit.

METHODS AND MATERIALS

This unit is composed of a linac, CT, and motorized table. The linac and CT are set up at opposite ends of the table, which is suitable for both machines. The gantry axis of the linac is coaxial with that of the CT scanner. Thus, the center of the target detected with the CT can be matched easily with the gantry axis of the linac by rotating the table. Positioning is confirmed with the CT for each treatment session. Positioning and treatment errors with this unit were examined by phantom studies. Between August and December 1994, 8 patients with 11 lesions of primary or metastatic brain tumors received SRT with this unit. All lesions were treated with 24 Gy in three fractions to 30 Gy in 10 fractions to the 80% isodose line, with or without conventional external beam radiation therapy.

RESULTS

Phantom studies revealed that treatment errors with this unit were within 1 mm after careful positioning. The position was easily maintained using two tiny metallic balls as vertical and horizontal marks. Motion of patients was negligible using a conventional heat-flexible head mold and dental impression. The overall time for a multiple noncoplanar arcs treatment for a single isocenter was less than 1 h on the initial treatment day and usually less than 20 min on subsequent days. Treatment was outpatient-based and well tolerated with no acute toxicities. Satisfactory responses have been documented.

CONCLUSION

Using this treatment unit, multiple fractionated SRT is performed easily and precisely without cranially fixated stereotactic frames.

Traumatic cervical tracheal disruption: report of two cases

We report herein the cases of two patients who suffered tracheal disruption, both of whom underwent successful surgical treatment. The first patient was a 48-year-old truck driver who suffered severe dyspnea after jamming his neck in a truck door. An endotracheal tube was unable to be inserted due to bleeding and thus, an emergency tracheostomy was performed. On admission massive subcutaneous emphysema was noted in the neck and anterior chest, and tracheal disruption was confirmed by a lateral neck X-ray, computed tomography (CT), and fiberscopy. An emergency end-to-end anastomosis of the trachea with insertion of a T-type silicon tube into the lower trachea was performed. The second patient was a 36-year-old man who suffered severe dyspnea after having his neck caught in a chain while driving a motorcycle. On admission, marked subcutaneous emphysema in the neck and paradoxical movement of the trachea were noted. Tracheal disruption was confirmed by a lateral neck X-ray and CT, and a similar operation to that of the first patient was performed. This type of injury is rare; however, lateral neck X-ray, CT, and fiberscopy proved extremely useful for making an accurate diagnosis following which successful emergency surgery was able to be performed, achieving good long-term results.

[An outbreak of waterborne Cryptosporidiosis in Kanagawa, Japan]

An outbreak of diarrhea due to infection with Cryptosporidium occurred among the staff members and customers who visited one of the 10 public houses or a dancing school in a building in Hiratsuka, Kanagawa Prefecture, at the end of summer in 1994. The epidemiological surveys by a questionnaire revealed that 461 out of 736 persons investigated complained of cholera-like or flu-like illness. The clinical manifestations included mucous and/or watery diarrhea (96.7%), abdominal pain (61.6%), fever (54.2%: lower than 39 degrees C = 84.1%, higher than 39 degrees C = 15.9%), malaise (37.1%), nausea (32.8%) and headache (29.3%). The polluted drinking water was strongly suspected to be the immediate cause of infection. Although several species of pathogenic bacteria were isolated both from stool and water samples, they were not supposed to be linked to the outbreak. No known enteropathogenic virus was found in either of the samples. Oocysts of Cryptosporidium parvum were identified in 12 (48.0%) of the 25 stool samples. The oocysts were also found in tap water and other water samples from a receiving tank which was directly connected with the public waterworks, and an elevated tank on the roof, a wastewater pits, a soil pit and artesianspring water tank. These tanks and pits except for the elevated tank were built adjucent to each other on an underground floor of the building. These tanks and pits were connected with openings in the upperpart of the tank walls. These openings might have functioned to discharge excess of drinking water in the receiving tank to the wastewater pit. The water level of the wastewater pit is kept down below the openings by pumping out the sanitary sewage to the public drain. According to the declaration of the owner of the building, however, the wastewater pump was broken at the time of outbreak. Accidental malfunction of the drainage system caused contamination of drinking water with sanitary sewage through the connecting pipes.

Preoperative diagnosis of intratemporal facial nerve tumor: high-resolution CT and otoscopic findings in 4 cases

Four cases of facial nerve tumor were treated in our clinic during the past 16 years, one of which was a recurrence 12 years after the resection. Another case presented with relapsing facial palsy of sudden onset. The others presented with slowly progressive facial palsy. In each of the four cases, the horizontal and vertical portions were included in the tumor extension, and a mass was revealed in the posterior tympanic cavity by use of otoscopy. High-resolution CT, performed in all but the earliest case, proved to be the most valuable diagnostic tool, indicating the anatomical correlation of the tumor with the facial canal. With the diagnosis preoperatively established, facial reanimation procedure could be applied immediately after the tumor resection except in the recurrent case.

[Long-term mechanical ventilation in Japan, with special reference to home mechanical ventilation]

Some patients in respiratory care units are difficult to wean from mechanical ventilation, and may be candidates for home mechanical ventilation (HMV). HMV may improve these patients' quality of life and decrease medical expenses. Since 1987, six nationwide questionnaire surveys were done to study the status of long-term mechanical ventilation (defined as mechanical ventilation for at least 90 days) and HMV in Japan. In 1994, an additional questionnaire regarding opinions about HMV was sent to physicians, patients undergoing HMV, their families, and people in companies that deal with home ventilators. From 1987 to 1994, the number of patients who had been mechanically ventilated for at least 90 days increased from 368 to 956. According to the 1994 survey, 565 of those patients were not candidates for HMV, 235 of them were candidates for HMV but could not be shifted (reasons are given below), and 156 were shifted to HMV. The reasons that some patients who were considered to be candidates for HMV could not be shifted included a lack of caregivers at home (58.1%), the cost of a ventilator (44.5%), lack of proper health insurance (39.8%), problems with ventilator maintenance and delays in obtaining repairs (37.7%), and inadequacies in the system for providing medical care in the home (33.1%). Despite the problems entailed in shifting to HMV, many patients undergoing HMV (77.8%) and members of their families (83.3%) expressed a desire to continue this therapy. Many physicians (94.0%) said they believed that HMV improves the quality of life of patients with chronic respiratory failure. Some companies intend to begin renting ventilators for HMV. The use and development of HMV in Japan would be promoted if the national health insurance covered the costs of this therapy.

Isolation of promoters from Brevibacterium flavum strain MJ233C and comparison of their gene expression levels in B. flavum and Escherichia coli

A promoter probe shuttle vector suitable for the isolation of promoter elements from coryneform bacteria was constructed. This vector carried the neomycin phosphotransferase (NPTII) gene from transposon Tn5 as a reporter gene, and was capable of replication in both Escherichia coli and Brevibacterium flavum. The vector was used in the construction of a B. flavum library of 899 independently isolated promoter clones. Promoters with a wide range of activities in B. flavum, including some very strong promoter elements, were isolated. Comparative analysis suggests that significant differences between B. flavum and E. coli may exist in the determinants of promoter strength.

Role of transforming growth factor-beta 1 on platelet-induced enhancement of endothelin-1 production in cultured vascular endothelial cells

We and other investigators obtained evidence that platelets stimulate endothelin-1 (ET-1) production at both message and protein levels in vascular endothelial cells (ECs), and that platelet-derived transforming growth factor-beta 1 (TGF-beta 1) is responsible for this stimulation. In the present study, we examined the effects of acidification or heat treatment, known to activate latent TGF-beta 1, on the platelet supernatant-induced ET-1 production in cultured porcine aortic ECs. Supernatant of platelets (6.0 x 10(8) platelets/ml) aggregated by adenosine diphosphate contained large amounts of TGF-beta 1, but were almost in a latent form, and the proportion of active TGF-beta 1 in the supernatant was increased markedly in the case of acidification or heat treatment. These treatments also significantly potentiated the supernatant-induced stimulation of prepro ET-1 mRNA expression and the ET-1 release in ECs. Purified TGF-beta 1 also enhanced ET-1 release, dose-dependently, but the enhancement declined at the higher concentrations. Thus, powerful stimulation of ET-1 production by platelet supernatant after acidification or heat treatment cannot be explained only by increments in active TGF-beta 1. The supernatant-induced stimulation of ET-1 synthesis was significantly inhibited by concomitant treatment of TGF-beta 1 neutralizing antibody, but this inhibition was incomplete even at a concentration that abolished TGF-beta 1-induced maximal stimulation. These results suggest that platelet-induced stimulation and subsequent acidification and heat treatment-induced potentiation on endothelial ET-1 production depend closely on release and activation of TGF-beta 1 derived from platelets.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition by beraprost sodium of thrombin-induced increase in endothelial macromolecular permeability

Effect of beraprost sodium (BPS), a long-acting and orally active stable analogue of PGI2, on the macromolecular permeability of cultured vascular endothelial cells (HUVEC) was detected by the transport of FITC-albumin. Thrombin treatment resulted in induction of FITC-albumin transport across the endothelial cell monolayer. The albumin transport induced by thrombin was not accompanied by any damage to the cells. BPS had no effect on the permeability of resting endothelial monolayers, while BPS inhibited the thrombin-induced increase in the albumin permeability in a dose-dependent manner (30-1000 nM). Treatment of the cells with PGI2 or dibutyryl cAMP caused a significant inhibition of the thrombin-induced increase in the albumin permeability. These results strongly suggested that BPS suppressed the thrombin-induced macromolecular permeability in HUVEC through the elevation of its intracellular cAMP, and that BPS was a suppressor against inflammatory vascular changes such as exudation.

Cloning and sequence determination of the aspartase-encoding gene from Brevibacterium flavum MJ233

A 2.5-kb EcoRI fragment containing the aspartase-encoding gene (aspA) of Brevibacterium flavum MJ233 was cloned into plasmid pUC18 using Southern hybridization with the Escherichia coli aspA gene as a probe. The complete nucleotide (nt) sequence of the cloned DNA indicated that the deduced gene product of the Br. flavum aspA is composed of 526 amino acids (aa). Comparison of the aa sequence to the corresponding sequences from E. coli, Bacillus subtilis and Pseudomonas fluorescens revealed 63, 47 and 57% homology, respectively. The aspA product was determined to have a size of approx. 57 kDa by SDS-PAGE.

Time course of appearance of ofloxacin in human scalp hair after oral administration

The time course of appearance of antimicrobial ofloxacin (OFLX) in human scalp hair was monitored in three healthy male volunteers after the oral administration of 100 mg OFLX three times daily for 2 consecutive days. Hair samples were collected from each subject by plucking several strands of frontal hair every day from 1 till 16 days after administration. A single hair was dissolved in 1 M NaOH to extract OFLX by chloroform, and the drug was measured by high-performance liquid chromatography and fluorescence detection. OFLX started to appear in the hair 1 to 3 days after administration and reached the maximal level approximately 4 to 9 days, remaining at almost the same level thereafter. This finding suggests the slow transfer of OFLX from hair follicle cells to hair matrix may be due to the slow dissociation of OFLX from bound melanin.

Transposon mutagenesis of coryneform bacteria

The Corynebacterium glutamicum insertion sequence IS31831 was used to construct two artificial transposons: Tn31831 and miniTn31831. The transposition vectors were based on a gram-negative replication origin and do not replicate in coryneform bacteria. Strain Brevibacterium flavum MJ233C was mutagenized by miniTn31831 at an efficiency of 4.3 x 10(4) mutants per microgram DNA. Transposon insertions occurred at different locations on the chromosome and produced a variety of mutants. Auxotrophs could be recovered at a frequency of approximately 0.2%. Transposition of IS31831 derivatives led not only to simple insertion, but also to cointegrate formation (5%). No multiple insertions were observed. Chromosomal loci of B. flavum corresponding to auxotrophic and pigmentation mutants could be rescued in Escherichia coli, demonstrating that these transposable elements are useful genetic tools for studying the biology of coryneform bacteria.