The so-called chromosomal verotoxin genes are actually carried by defective prophages.
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Bacterial Toxins↗
Biomedical subjects
N Nakazono
Publications and source records attributed to N Nakazono.
Generation of new transposons in vivo: an evolutionary role for the "staggered" head-to-head dimer and one-ended transposition.
From a plasmid carrying the tnpA gene and one inverted repeat sequence (IR) of transposon Tn3, plasmids containing a structure characteristic of transposons, i.e., two IRs flanking a tnpA gene, were generated spontaneously in vivo. They appear to have arisen either through the formation of a "staggered" head-to-head dimer or by so-called one-ended transposition. These putative transposons could indeed transpose to, or form cointegrates with, a recipient plasmid. Based on these findings it is proposed that a primeval transposase gene and its target site evolved first, and subsequently gave rise to a "fully-fledged" transposon by head-to-head dimerization or one-ended transposition.
Base Sequence↗
Mechanism of oxidative damage to fish red blood cells by ozone.
The present study was conducted to elucidate the adverse effects of ozone exposure on rainbow trout (Oncorhynchus mykiss) red blood cells (RBCs). We evaluated whether hemoglobin (Hb) or Hb-derived free iron could participate in the RBC damage using an in vitro ozone exposure system. Ozone exposure induced hemolysis, formation of methemoglobin, and RBC membrane lipid peroxidation. This RBC damage was not suppressed by the addition of a specific iron chelator (deferoxamine mesilate) to the medium but was suppressed by carbon monoxide (CO) treatment before ozone exposure. Generation of hydrogen peroxide (H2O2) in RBC was observed upon ozone exposure but was significantly suppressed by CO treatment before ozone exposure. Thus the Hb status (i.e., Hb redox condition) and H2O2 generation in RBC should play important roles in mediating RBC damage by ozone exposure. In other words, neither ozone nor its derivative directly attacked from the outside of the cell, but ozone that penetrated through the membrane derived the reactive oxygen species from Hb inside of the cell.
Animals↗
The molecular basis of the instability of a crp- mutation in Escherichia coli.
We have described a rapid spontaneous conversion in the stationary phase of Escherichia coli strain DOO (crp-) cells as a whole population to crp+ state (Sugino and Morita, 1994). In this paper we have tried to elucidate the molecular basis of this unidirectional conversion by cloning and sequencing of the crp gene in their crp+ and crp- states. We have found that in the original crp- strain, an IS2 element has been inserted between its original promoter and the coding region of the crp gene in the so-called orientation II (Ahmed et al., 1981), accompanied by an 11 bp deletion. Unexpectedly, the crp+ "revertants" derived from the crp- mutant had no difference in sequence from the crp-, either in the coding or the regulatory region. This suggests that a change at another locus, such that this change somehow activates the expression of the crp gene to the level of a normal crp+, is responsible for the apparent reversion from crp- to crp+.
Base Sequence↗
Immunologic reactivity on one year follow-up of subjects without allergy to Hymenoptera stings.
We studied Hymenoptera stings in 72 pest-control operators without any previous systemic reactions to Hymenoptera stings, and investigated their venom-specific IgE levels in serial specimens collected over one year. At the initial evaluation, venom-specific IgE was present in 25 (34.7%) of 72 pest-control operators, and venom-specific IgE titer significantly decreased as the time interval from the last sting increased (p < 0.001). In most cases, venom-specific IgE disappeared less than 3 years after the last sting. On the other hand, the ratio of subjects with positive CAP for venom-specific IgE was significantly increased with an elevation of total serum IgE level (p < 0.001). After the one year follow-up, venom-specific IgE titer in the 25 subjects with positive CAP decreased significantly (p = 0.026). Total serum IgE level modified the decline significantly (p = 0.011), but the time interval from the last sting did not. In elevated total IgE level (>250 IU/ml), the decline of venom-specific IgE tended to be slow.
Adult↗
[Change in venom-specific IgE levels during 2-year follow-up in five cases with a history of Hymenoptera sting].
Levels of specific IgE antibodies to three kinds of venom (honeybee, wasp and yellow jacket) were followed up for two years in five male pest control operators (age: 24 to 50 years) with Hymenoptera sting within the latest six months. At the first examination, all subjects had a positive reaction for venom-specific IgE but their levels were varied in the range from class 2 to 5 (0.70 approximately 99.9 UA/ml), and a positive reaction was observed in the case of unoffending Hymenoptera. A subject who was re-stung during the two-year follow-up period showed increase in all of the venom-specific IgE levels. Of four subjects without re-stung during the two years, three subjects had a logarithmic decrease in all the specific IgE levels time-dependently, but one subject with a high total serum IgE level showed an increase and decrease alternately in the specific IgE The total serum IgE level may be a factor which influences the change in the venom-specific IgE level. In the four subjects without a high total serum IgE level, the biological half-life of venom-specific IgE was estimated to be 6 to 12 months based on the decreased level during the follow-up period.
Adult↗
Nested deletions from a fixed site as an aid to nucleotide sequencing: an in vitro system using Tn3 transposase.
We have previously constructed a cloning/sequencing vector, with an in vivo system capable of creating nested deletions from the end of transposon Tn3, which is useful for sequencing large DNAs. Here we report an in vitro system which uses an ammonium sulfate fraction of extract from E. coli cells harboring a Tn3 transposase overproducer plasmid to generate nested deletions. A key feature of the procedure is exhaustive digestion of the reaction products with a restriction enzyme that cleaves only between the Tn3 "right" terminus and the cloned fragment. This step reduces the noise level due to mechanisms other than deletions from the Tn3 terminus, and facilitates detection and isolation of the desired deletion products. This system enables us to save at least 2 days' time when obtaining the necessary deletions compared with the in vivo system.
Bacteriophage lambda↗
The effect of the crp genotypes on the transformation efficiency in Escherichia coli.
We have found that a significant difference exists in transformation efficiency between the crp+/crp- isogenic pair of strains of Escherichia coli, with the efficiency being much higher in crp- than in crp+. The ratio of transformation efficiency between crp+ and crp- strains depends very little on the plasmid size. This observation suggests that the difference of the transformation efficiency is due to mechanisms other than a crp-regulated endonuclease. The crp gene is one of the first specific genes that have been shown to affect transformation efficiency.
Bacteriophage M13↗
[Longitudinal study on association between care conditions and mortality among frail elderly living at home].
In order to elucidate the association between care conditions and mortality rate, a two year longitudinal study was performed on 115 frail elderly living at home. The main results were as follows; 1. Of the 115 frail elderly, 45 persons (39.1%) died during the two years. 2. A multiple logistic regression analysis revealed that the following factors were correlated to their death: age, activities of daily living (ADL), type of bedding. 3. Although ADL level was lower in the bed group than the Japanese style bed (futon) group at the first survey, survival rate was 69.8% in bed group and 47.5% in futon group. The relative risk of death with beds was 0.61 (95% confidence intervals 0.38-0.96) and was statistically significant.
Activities of Daily Living↗
Hepatitis E virus (87A strain) propagated in A549 cells.
A strain of hepatitis E virus (HEV), the 87A strain isolated in 2BS cells from the feces of a patient with hepatitis E, has been reported previously. In this study, the 87A strain was propagated in A549 cells, and the marked cytopathic effect (CPE) appeared in the infected monolayer cells. The size of this virus is about 30 nm in diameter. Furthermore, HEV-RNA from the supernatants of the virus of different passages was detected by polymerase chain reaction (PCR) amplification using ET1.1 HEV primers. A band of HEV for 239 bp from PCR products was revealed by electrophoresis. PCR products of the fourth passage were sequenced. These results show that the 87A virus replicates in the A549 cell line.
Animals↗
Existing variations on the gene structure of hepatitis E virus strains from some regions of China.
The isolation and identification of the 87A strain of hepatitis E virus (HEV) by means of cell culture have been described previously. This paper reports the nucleotide sequence of a portion of this HEV strain. The RNA extracted from the supernatants of the different passages of the 87A strain cultured in the A549 cell line was reverse-transcribed (RT) to cDNA, and then the polymerase chain reaction (PCR) amplification was carried out using the primers of HEV ET1.1 region. The PCR products from 1) the supernatant of the infected cells at the fourth passage, 2) the virus concentrated by polyethylene glycol (PEG) precipitation at the tenth passage, and 3) the virus purified by a sucrose gradient at the tenth passage were sequenced. In addition, three other PCR products obtained from sera of acute hepatitis E patients in Beijing (B-9) and Guangzhou (G-9 and G-20) were also sequenced. The nucleotide sequences of the above four strains of HEV (located in the genome from positions 4545-4754) were compared to those of some reported HEV strains. The nucleotide sequences of the B-9 strain and the 87A strain were similar to the Burmese strain and may belong to the same branch of HEV. The nucleotide sequences of the G-9 strain and the G-20 strain were a novel and unique branch. The Chinese HEV strains are multiplex and variable in gene structure.
Acute Disease↗
Effect of ingestion of 6-propyl-2-thiouracil on biochemical indices of selenium status in rats.
Biochemical indices of selenium (Se) deficiency (liver Se content and glutathione peroxidase (GSHPx) activity, and urinary ketone bodies during fasting) were measured in Se-deficient or Se-sufficient control rats with or without ingestion of 6-propyl-2-thiouracil (PTU). Male weanling Wistar rats (50 to 60 g) were fed on a Torula yeast-based Se-deficient diet (Se content, < 0.01 microgram/g), or on the same diet supplemented with sodium selenite (0.1 microgram Se/g). The rats were given 0.05% PTU solution or deionized water as drinking water. After feeding for 6 weeks, the rats given PTU showed severe inhibition of growth and marked decreases in serum thyroxine (T4) and 3,5,3'-triiodothyronine (T3) levels. Animals fed the Se-deficient diet showed remarkably low hepatic Se content and GSHPx activity compared to the Se-sufficient control rats, irrespective of PTU-ingestion. In the rats without PTU, the Se deficiency was accompanied by significantly elevated serum T4 and lower T3 levels. Urinary ketone body excretion during fasting was significantly higher in the Se-deficient rats than in controls, irrespective of serum thyroid hormone levels. These results suggest that the increase in urinary ketone body excretion in Se deficiency may be independent of serum thyroid hormone.
Animals↗
[Hepatitis E: etiology and clinics of another enterically transmitted hepatitis].
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Animals↗
[A survey of utilization of urinary alarm systems in nursing homes].
A questionnaire survey was performed on 63 nursing homes and 1006 care workers in the nursing home, in order to elucidate the actual state of utilization of urinary alarm systems (systems). About 3% of the nursing homes in all of Japan are utilizing the system with 12.5% of all institutionalized elderly having a diaper sensor of those nursing homes with the system, 86% use the system continually. In 51% of the nursing homes, care workers change diapers immediately after sensor alarm is triggered. The reasons for not being able to change the diaper immediately were either care workers had other pressing work, or simultaneous or overlapping sensor alarm calls occurred. The usefulness of the system was recognized for "prevention of decubitus" (66%), "prevention of contact dermatitis from diapers" (82%), "decrease of ammonia smell" (27%), and "discontinuation of diaper" (26%). As for problems associated with the system or factors that increase work load, responses included "sensor does not respond sometimes" (67%), "increased diaper changes" (53%), "increased nurse calls due to urinary urgency" (41%), and "disconnection of the sensor by the patient" (34%). The percentage of care workers who reported an increase in work load was 73%, especially where the ratio of care workers number/institutionalized elderly was low.
Adult↗
Improvement of urinary delta-aminolevulinic acid determination by HPLC and fluorescence detection using condensing reaction with acetylacetone and formaldehyde.
We improved the method for determining urinary delta-aminolevulinic acid (ALA) by HPLC-fluorometer after pre-column derivatization with acetylacetone and formaldehyde, and a stable ALA derivative was obtained without any effect from various urinary components as demonstrated by the complete recovery of ALA (100.9 +/- 5.5%, n = 85) from the urine samples. The modified procedure was as follows: Twenty microliters of urine sample, 5 ml of acetylacetone solution (acetylacetone/ethanol/distilled water containing 4 milligrams of NaCl; 15/10/75), and 0.45 ml of 9.3% formaldehyde solution were mixed and boiled for 15 min. The fluorescent derivative of ALA was separated and analyzed by HPLC with the fluorometer at Ex 246 nm and Em 458 nm. Using a gradient program, the retention time of the ALA derivative was 7.3 min and the analysis could be repeated at 13 min intervals. Concentrations of ALA in urine samples measured by this method were significantly correlated with those measured by the Mauzerall-Granick (M-G) method (n = 85, r = 0.993, p < 0.001). The values obtained by our method were, however, lower than those obtained by the M-G method. Urinary ALA concentrations of 40 non-lead workers ranged from 0.1 to 2.3 mg/g creatinine with the mean +/- SD of 1.1 +/- 0.4 mg/g creatinine as measured by the present method.
Adult↗
Seroepidemiological study of coxsackievirus type A24 variant (CA24v) in Taiwan.
In October 1985 and June 1986, for the first time, Taiwan experienced two outbreaks of acute hemorrhagic conjunctivitis (AHC) caused by a variant of coxsackievirus A24 (CA24v). Sera of virologically and clinically confirmed cases were studied together with the pre- and post-epidemic serum samples by the microneutralization method (cut-off titer, 1:8). The serum samples included 16 cases of virologically confirmed AHC and 18 cases of clinically diagnosed AHC which were collected during the period of January to July, 1987 (i.e., 7 to 21 months after the epidemic). In the same period of time, 374 serum samples were randomly collected as a post-epidemic control group. Meanwhile, 206 serum samples, which were randomly collected in 1980, were studied as a pre-epidemic control group. The results showed that in terms of CA24v neutralizing antibody (NTAb) positivity, a significant difference was found between the pre- and post-epidemic random sample groups (5.3% vs. 28.1%, P < 0.001) while no significant differences among the virologically confirmed, the clinically diagnosed and the post-epidemic random sample groups were noticed (31.3% vs. 28.1%; 44.4% vs. 28.1%, P > 0.05). For comparison, the enterovirus 70 (EV70) NTAb of the samples was studied simultaneously. The results showed that the positive rate and geometric mean titer of CA24v NTAb were lower than those of EV70 even in the post-epidemic serum samples collected shortly after the CA24v epidemic.
Adolescent↗
[Caregiving burden of elderly caregivers who provide at home care for infirm elderly].
In order to elucidate the degree of feeling burdened and factors affecting caregiving burden of elderly caregivers, a questionnaire survey was performed on 241 female caregivers of infirm elderly. The surveyed group consisted of 138 caregivers under 60 years of age (young group) and 103 aged 60 and over (old group). The major results of this survey were as follows, 1) Conditions perceived as unfavorable in the old group were related to caregiving assistants, number of the family members and health condition of the caregiver. 2) Greater number of infirm elderly with serious ADL problems and higher average body weight of the elderly cared for were seen for the old group than the young group. 3) The old group had a larger number of problem incidents and expressed more eager desire for transfer of elderly to institutional care than providing the young group. 4) A feeling of burden in daily care appeared larger for night care, body discharge disposal and bathing care of the elderly and was more frequent in those above 70 than under 70 years of age. 5) Hours in bed were longer and range of movement by wheel chair was more limited for infirm elderly as the caregiver's age increased. These results suggest that the above-mentioned unfavorable conditions in elderly caregivers promote a state of becoming bedridden and a lowering of ADL ability of infirm elderly.
Activities of Daily Living↗
[Improvement of urinary delta-aminolevulinic acid determination by HPLC-fluorometry using pre-column derivatization].
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Adult↗