Requirement of the Pseudomonas aeruginosa tonB gene for high-affinity iron acquisition and infection

To investigate the contribution of the TonB protein to high-affinity iron acquisition in Pseudomonas aeruginosa, we constructed tonB-inactivated mutants from strain PAO1 and its derivative deficient in producing the siderophores pyoverdin and pyochelin. The tonB mutants could not grow in a free-iron-restricted medium prepared by apotransferrin addition, even though the medium was supplemented with each purified siderophore or with a heme source (hemoglobin or hemin). The tonB inactivation was shown to make P. aeruginosa unable to acquire iron from the transferrin with either siderophore. Introduction of a plasmid carrying the intact tonB gene restored growth of the tonB mutant of PAO1 in the free-iron-restricted medium without any supplements and restored growth of the tonB mutant of the siderophore-deficient derivative in the medium supplemented with pyoverdin, pyochelin, hemoglobin, or hemin. In addition, animal experiments showed that, in contrast to PAO1, the tonB mutant of PAO1 could not grow in vivo, such as in the muscles and lungs of immunosuppressed mice, and could not kill any of the animals. The in vivo growth ability and lethal virulence were also restored by introduction of the tonB-carrying plasmid in the tonB mutant. These results indicate clearly that the intact tonB gene-and, therefore, the TonB protein encoded by it-is essential for iron acquisition mediated by pyoverdin and pyochelin and via heme uptake in P. aeruginosa and suggest that the TonB-dependent iron acquisition may be essential for P. aeruginosa to infect the animal host.

Higher incidence of diabetic nephropathy in type 2 than in type 1 diabetes in early-onset diabetes in Japan

BACKGROUND

Whether the type of diabetes, race, and year and age of diagnosis affect the incidence of diabetic vascular complications is unknown. That both type 1 and type 2 diabetes occur in the young Japanese population prompted us to investigate whether the type of diabetes and the year of diagnosis are related to the incidence of nephropathy.

METHODS

Of the 17,256 diabetic patients who visited the outpatient clinic at our diabetes center between 1965 and 1990, 1578 (9.1%) had early-onset diabetes (diagnosed before the age of 30); of these, 620 (39%) had type 1, and 958 (61%) had type 2 diabetes. The incidence of nephropathy was analyzed in the patients according to postpubertal duration and year of diagnosis.

RESULTS

The cumulative incidence of nephropathy after 30 years of postpubertal diabetes was significantly higher (P < 0.0001) in type 2 diabetic patients (44.4%, 95% CI, 37.0 to 51.8%) than in type 1 diabetic patients (20.2%, 95% CI, 14.9 to 25.8%). The incidence of nephropathy among type 1 diabetic patients has declined during the past two decades, whereas it has not among type 2 diabetic patients. The rate ratio for type 2 diabetic patients diagnosed between 1980 and 1984 relative to type 1 diabetic patients diagnosed in the same period was 2.74 (95% CI, 1. 17 to 6.41).

CONCLUSIONS

The incidence of nephropathy has declined in Japanese patients with type 1 but not in those with type 2 diabetes. In young Japanese patients, because of the higher incidence of nephropathy in type 2 diabetes and the higher prevalence of type 2 than type 1 diabetes, type 2 diabetes is likely the major cause of diabetic nephropathy.

Endoscopic piecemeal resection with submucosal saline injection of large sessile colorectal polyps

BACKGROUND

Because endoscopic en bloc resection of large, sessile colorectal polyps is technically difficult, they are usually resected piecemeal. However, piecemeal resection makes it difficult to evaluate the completeness of the resection histopathologically. In this study the efficacy of endoscopic piecemeal resection of large, sessile colorectal polyps was investigated after follow-up greater than 1 year.

METHODS

We removed 56 sessile colorectal polyps 2 cm or greater in diameter in 56 patients by using an endoscopic submucosal saline injection technique. Endoscopic examinations were repeated at 3, 6, and 12 months and longer after initial endoscopic resection. If no residual tumor was found endoscopically and histologically, the patient was considered to be "cured."

RESULTS

Of the 56 polyps, 14 (25%) were resected en bloc, and 42 (75%) were resected piecemeal. Of the 42 patients treated with piecemeal resection, 23 (55%) required additional endoscopic or surgical interventions. In patients followed 1 year or longer after initial treatment, the cure rate by en bloc resection was 100% (14 of 14) and that by piecemeal resection was 83% (35 of 42). Arterial bleeding occurred in 4 patients (7%) during or after endoscopic resection. In 3 of them, bleeding was stopped by endoscopic clipping, but 1 patient required emergent laparotomy.

CONCLUSIONS

Endoscopic piecemeal resection after submucosal saline injection with an intensive follow-up program is a safe and effective treatment for large, sessile colorectal polyps.

Expression and responsiveness of human interleukin-18 receptor (IL-18R) on hematopoietic cell lines

Interleukin-18 (IL-18) is a new inflammatory cytokine sharing biological functions with IL-12. The human IL-18 receptor (IL-18R) was recently identified and was found to be expressed on normal peripheral blood lymphocytes. To further characterize IL-18R, we analyzed IL-18R expression using a series of human hematopoietic cell lines selected from various cell lineages. We found the IL-18R expression on cells of T and B lineages as expected from analysis on normal cells. The IL-18R expression, however, was found not to be restricted to any specific maturation stages of T and B cells. In addition, we detected IL-18R expression in myeloid, monocytoid, erythroid and megakaryocytic cell lines, indicating that normal counterparts of these cell lineages could express IL-18R and participate in in vivo reactions caused by IL-18. Biochemical studies showed that IL-18R proteins exist as heterogeneous molecules ranging from 60 to 110 kDa. Deglycosylation experiments indicated that the heterogeneity could not be explained only by a difference in glycosylation. We also found that tumor necrosis factor-alpha (TNF-alpha) modulated the IL-18R expression, which implies an important in vivo effect of TNF-alpha on IL-18-induced reaction. Analyzing the responsiveness of IL-18R, we found that only KG-1 responded to IL-18 stimulation. This suggests that certain inhibitory mechanisms of IL-18 responsive genes are involved in the all IL-18R-positive cell lines except KG-1.

Expression of adrenomedullin by human granulosa lutein cells and its effect on progesterone production

OBJECTIVE

Adrenomedullin (AM) has diverse functions and is expressed in a variety of tissues. This study was conducted to investigate the expression of AM in the human ovary and its effect on progesterone production by human granulosa lutein cells.

DESIGN AND METHODS

Follicular fluid and blood samples were obtained at the time of oocyte retrieval from patients undergoing in vitro-fertilization cycles. Concentrations of AM in follicular fluid and plasma were measured by RIA. Granulosa cells were isolated from follicular fluid and expression of AM mRNA was examined by RT-PCR. Granulosa lutein cells were cultured in vitro and secretion of AM by those cells was determined by immunoprecipitation followed by PAGE. Immunohistochemical staining with human ovaries was carried out, using a specific antibody to AM. Furthermore, the effect of AM on progesterone production by cultured granulosa lutein cells was studied.

RESULTS

Concentrations of AM in follicular fluid collected just before ovulation were significantly higher than those in the plasma (P<0.01). AM mRNA was expressed in granulosa cells at the preovulatory stage. Cultured granulosa lutein cells secreted immunoreactive AM. With immunohistochemical staining, it was revealed that AM was most abundantly expressed in granulosa lutein cells at the midluteal phase. No appreciable staining for AM was observed in granulosa cells in primordial and preantral follicles, whereas immunolocalization of AM was noted in granulosa cells of dominant follicles although it was not as prominent as in granulosa lutein cells at the midluteal phase. Furthermore, addition of AM to cultured granulosa lutein cells augmented progesterone secretion in a dose-dependent manner.

CONCLUSIONS

These results suggest that AM is transcribed and secreted in human granulosa lutein cells as a local factor to enhance progesterone production by those cells.

New Cdc25B tyrosine phosphatase inhibitors, nocardiones A and B, produced by Nocardia sp. TP-A0248: taxonomy, fermentation, isolation, structural elucidation and biological properties

Strain TP-A0248 which produces two new Cdc25B tyrosine phosphatase inhibitors and also possessing antifungal activity, designated nocardiones A (1) and B (2), was considered to belong to the genus Nocardia on the basis of literature comparison of chemotaxonomic properties. The nocardiones were isolated by solvent extraction of fermentation broth of Nocardia sp. TP-A0248 and purified by the conventional column chromatography. Spectroscopic studies led to determination that 1 and 2 belong to a class compound of naphtho[1,2-b]furan-4,5-diones. Compound 1 inhibited the activity of Cdc25B, PTP1B and FAP-1 protein tyrosine phosphatases at a concentration of 10 microM. It also showed moderate in vitro antifungal and cytotoxic activity.

Impact of siderophore production on Pseudomonas aeruginosa infections in immunosuppressed mice

Pseudomonas aeruginosa produces siderophores, pyoverdin and pyochelin, for high-affinity iron uptake. To investigate their contribution to P. aeruginosa infections, we constructed allelic exchange mutants from strain PAO1 which were deficient in producing one or both of the siderophores. When inoculated into the calf muscles of immunosuppressed mice, pyochelin-deficient and pyoverdin-deficient mutants grew and killed the animals as efficiently as PAO1. In contrast, the pyochelin- and pyoverdin-deficient (double) mutant did not show lethal virulence, although it did infect the muscles. On the other hand, when inoculated intranasally, all mutants grew in the lungs and killed immunosuppressed mice. Compared with PAO1, however, the pyoverdin-deficient mutant and the double mutant grew poorly in the lungs, and the latter was significantly attenuated for virulence. Irrespective of the inoculation route, the pyoverdin-deficient and doubly deficient mutants detected in the blood were significantly less numerous than PAO1. Additionally, in vitro examination demonstrated that the growth of the double mutant was extremely reduced under a free-iron-restricted condition with apotransferrin but that the growth reduction was completely canceled by supplementation with hemoglobin as a heme source. These results suggest that both pyoverdin and pyochelin are required for efficient bacterial growth and full expression of virulence in P. aeruginosa infection, although pyoverdin may be comparatively more important for bacterial growth and dissemination. However, the siderophores were not always required for infection. It is possible that non-siderophore-mediated iron acquisition, such as via heme uptake, might also play an important role in P. aeruginosa infections.

Tomographic assessment of vitreous surgery for diabetic macular edema

PURPOSE

To evaluate the retinal structure before and after vitrectomy for diabetic macular edema and to assess the correlation between thickness of neurosensory retina and best-corrected visual acuity.

METHODS

Tomographic features of 13 eyes (nine patients) with diabetic macular edema were prospectively evaluated with optical coherence tomography before and after vitrectomy. The foveal thickness (the distance between the inner retinal surface and the retinal pigment epithelium) and the retinal thickness (thickness of neurosensory retina) were measured by optical coherence tomography preoperatively and postoperatively. The correlation of the best-corrected visual acuity with foveal and retinal thickness was determined.

RESULTS

All 13 eyes had retinal swelling with low intraretinal reflectivity. In addition to retinal swelling, there were cystoid spaces in five (38%) of 13 eyes, a serous retinal detachment in three (23%), and both cystoid spaces and serous detachment in three (23%). Six months postoperatively, the mean foveal thickness significantly decreased from 630 +/- 170 to 350 +/- 120 microm (P <.01, paired t test) and the mean thickness of neurosensory retina decreased from 540 +/- 160 to 320 +/- 140 microm (P <.01, paired t test). A serous retinal detachment occurred transiently in 3 eyes. Compared with the preoperative level, the postoperative best-corrected visual acuity level improved by more than 2 lines in five of the 13 eyes (38%), remained the same in seven eyes (54%), and decreased in one eye (8%). The postoperative thickness of neurosensory retina at the fovea and best-corrected visual acuity level at the sixth postoperative month had a strong negative correlation (correlation coefficient, -0.76; P <.01, Spearmans rank test).

CONCLUSIONS

Vitrectomy was generally effective in treatment of diabetic macular edema. Optical coherence tomography demonstrated the intraretinal changes of macular edema and the process of edema absorption. During the process of macular edema absorption, intraretinal fluid appeared to move into the subretinal space in some cases. Best-corrected visual acuity improvement was greater in eyes with less preoperative increase in thickness of neurosensory retina.

IFN-gamma-dependent and -independent mechanisms in adverse effects caused by concomitant administration of IL-18 and IL-12

IL-18 is a new type of inflammatory cytokine similar to but distinct from IL-12 and IL-1beta. One intriguing property of IL-18 is synergism with IL-12 in many respects. In this study we examined the in vivo synergistic effects of IL-18/IL-12 in mice and found lethal toxicity accompanying an elevated IFN-gamma level in the serum. Since treatment with IL-18 alone did not have any apparent toxicity, and treatment with IL-12 alone showed only limited toxicity in our system, the synergy between the two cytokines was all the more remarkable. The major symptoms of the toxicity were weight loss, diarrhea, hemorrhagic colitis, splenomegaly, fatty liver, and atrophic thymus, most of which are similarly found in endotoxin-induced septic shock. However, in contrast to septic shock, TNF-alpha was not induced. The involvement of IFN-gamma in the toxicity was further studied in detail. Treatment of athymic nude mice with anti-asialo-GM1 did not reduce the toxicity, whereas anti-IFN-gamma treatment of wild-type mice alleviated it. When IFN-gamma-deficient mice were treated with IL-18/IL-12, the majority of them showed mortality and toxicity with severe pulmonary edema. These results indicate that IL-18/IL-12 treatment induces severe adverse effects through not only IFN-gamma-dependent mechanisms but also IFN-gamma-independent processes.

Brillouin scattering study of epoxy adhesive layers during cure

The isothermal curing process of thin epoxy adhesive layers (mixture of a bisphenol A-based epoxy prepolymer and an aliphatic diamine curing agent) has been investigated. The Brillouin scattering technique with 90 degrees A scattering geometry enables simultaneous measurements of longitudinal and shear wave properties in the GHz range. Observed longitudinal and shear wave velocities showed similar changes during cure. They rapidly increased and gradually became constant, reflecting the elastic changes of the epoxy layer. The final velocities, however, clearly depended on the curing temperature. Taking the glass transition process of epoxy resins into consideration, these curing behaviors in thin layers are discussed.

Axis location of tibial rotation and its change with flexion angle

The magnitude and location of the axis of tibial rotation were measured at 15 degrees increments between 0 degree and 90 degrees flexion using 24 normal anatomic knee specimens, and their changes with flexion angle were investigated. The magnitude of tibial rotation was small (8.3 degrees) at 0 degree flexion, but increased rapidly as the flexion angle increased and reached a maximum rotation (31.7 degrees) at 30 degrees flexion. It then decreased again with additional flexion (24.8 degrees at 90 degrees flexion). The location of the axis was close to the tibial insertion of the anterior cruciate ligament at 0 degree flexion, gradually moving toward insertion of the posterior cruciate ligament (observed at 45 degrees and 60 degrees flexion), and then moved anteriorly again with additional flexion: the axis was approximately equidistant from the two cruciate insertions at 90 degrees flexion. The results showed that a relatively large degree of tibial rotation was possible in a normal knee and that the location of the axis remained approximately in the area between the two cruciate ligament insertions throughout the range of flexion. However, the location of the axis changed with the flexion angle within this area according to the changes in direction and tension of the cruciate ligaments and the surrounding soft tissues.

Major complications during spasm provocation tests with an intracoronary injection of acetylcholine

This study sought to clarify major complications associated with acetylcholine testing. Serious major complications, such as sustained ventricular tachycardia, shock, and cardiac tamponade were determined in 4 of 715 patients (0.56%), but no cases of death or irreversible complications occurred. The spasm provocation test using acetylcholine should be performed carefully, although it is considered a safe and reliable method.

Adrenomedullin expression in the human endometrium

Immunohistochemical studies were performed using a specific antibody to human adrenomedullin (AM) to determine its presence and cellular localization in the human endometrium, in the different phases of the menstrual cycle, and in the postmenopausal period. Specimens were obtained from 21 patients who underwent abdominal hysterectomy for various reasons. The endometrium had no pathological lesion in all cases. In the early and mid proliferative phases of the menstrual cycle, no immunostaining for AM was noted in the endometrium. AM immunostaining in the endometrium became apparent in the late proliferative phase. The staining intensity of AM in the endometrium became more abundant in the secretory phase. No appreciable difference in the staining intensity of AM in the endometrium was noted among early, mid, and late secretory phases. Immunostaining for AM was evident in both the epithelial and stromal compartments of the endometrium. In the postmenopausal endometrium, there was intense immunostaining for AM only in the stromal compartment. This is the first study to demonstrate the expression of AM in the endometrium in relation to the menstrual cycle. The results obtained suggest the participation of AM in the growth and differentiation of the endometrium.

An electromyographic study of two different types of ballpoint pens--investigation of a one hour writing operation

Recently there has been an increasing incidence of occupational cervicobrachial disorders (OCD) and writer's cramp in office workers using ballpoint pens in writing operations. For the sake of workers who use ballpoint pens, it is essential to prevent such health hazards. It has been observed that a strong gripping pressure on the ballpoint pen significantly contributes to the development of these conditions. The present authors have been developing a new ballpoint pen by altering the grip area in such a way as to reduce the gripping pressure, and thus prevent OCD. The purpose of this study is to compare our ballpoint pen (new pen) with a conventional ballpoint pen (conventional pen) for the load that they exert on the upper limb during one hour of continuous writing. Electromyograms (EMG) and upper limb pain scores are used as indicators. The conventional pen used was selected from commercially available ballpoint pens widely used in offices. The grip area is cylindrical with an 8.3 mm diameter. It is manufactured of hard plastic, which can make it feel rigid and slippery to the user. The new pen has a cylindrical grip area that flares out at the bottom, near the pen-tip, and has a diameter ranging from 11.9-13.6 mm. In addition, the grip is constructed of a 2 to 3 mm-thick silicon rubber sleeve that is softer and less slippery in comparison with the conventional pen. Twelve students (5 males and 7 females) without any preexisting cervicobrachial disorders were asked to transcribe an English text for one hour, alternately using the two kinds of pens. The EMG of the flexor pollicis brevis was measured and recorded every second, while subjective pain scores were recorded every five minutes for the thumb, forefinger, middle finger, thenar, forearm extensor (forearm) and shoulder. The EMG of the flexor pollicis brevis and the pain scores for the thumb, forefinger, middle finger, forearm and shoulder were significantly lower for the new pen than for the conventional pen. These results suggest that after an hour of continuous writing, the new pen reduces the muscle load on the upper limb, and therefore mitigates fatigue in this area.

[Analyses of work-relatedness of health problems among truck drivers by questionnaire survey]

In order to estimate occupational risk factors for health problems among truck drivers, a questionnaire survey of working conditions, job content in truck transportation, subjective symptoms and present illnesses was carried out among 541 truck transportation workers in 1997. The valid response rate was 85.7%, and 134 local truck drivers, 199 long-distance truck drivers and 71 clerical workers were analyzed. First, to examine occupational risk factors and health problems among the three groups, the authors analyzed working conditions, job content in truck transportation, subjective symptoms and present illnesses. Second, to estimate the work-relatedness of health problems among local truck drivers and long-distance truck drivers, logistic regression analyses were conducted, and odds ratios and 95% confidence intervals were computed. The prevalence rates of working factors affecting health problems of truck drivers were significantly higher than those of clerical workers in the items on irregular shift work, working environment, working posture, handling heavy materials, job stress due to overloading and long working time and limited time off. The prevalence rates for subjective symptoms (ringing in the ears, neck pain and low back pain) and present illnesses (hypertension, ulcers in the digestive tract, back injuries, whiplash injuries and hemorrhoids) among truck drivers were significantly higher than those of clerical workers. In logistic regression analyses, many work-related items except age, BMI and smoking habit showed significantly higher odds ratios for subjective symptoms and present illnesses of truck drivers. Odds ratios for hypertension, heart diseases and related subjective symptoms among local truck drivers were significantly increased by job career, twisting posture, vibration and driving stress. Odds ratios for gastro-duodenal diseases and related subjective symptoms were significantly increased by narrow working space, sleeping in the truck, driving distance, squatting posture and driving stress. Odds ratios for ringing in the ears among local truck drivers were significantly increased by job career, long working time, narrow working space, sleeping in the truck and driving stress. Odds ratios for musculo-skeletal diseases and related subjective symptoms were significantly increased by overwork, vibration, narrow working space, sitting posture and shortage of recess. Odds ratios for fatigue symptoms were significantly increased by the shortage of recess, vibration and driving stress. In order to cope with the health problems of truck drivers, it is recommended that working conditions and work loads for among truck drivers as described above be improved.

Effects of the administration of wheat bran biscuit: changes in the diet

We developed hard biscuit containing 30% wheat bran (WB biscuit) and administered it to 12 volunteers at 7.5 g/day (7.5 g group) or 15 g/day (15 g group) as wheat bran for 12 weeks. After 12 weeks, the dietary fiber intake from foods other than wheat bran decreased slightly in the both groups, in the 15 g group was the decrease notable especially, after the beginning of WB biscuit administration. We suggest that a closest attention to changes in dietary habit associated with intervention is needed in intervention studies using patients leading a normal life.

Facilitated expansion of pneumococcal colonization from the nose to the lower respiratory tract in mice preinfected with influenza virus

A strain of Streptococcus pneumoniae, when inoculated intranasally in 2 microl of suspension into BALB/c mice preinfected with influenza virus, colonized first in the nose, and several days thereafter also colonized significantly in the trachea and lungs with purulent inflammation. Pneumoccocal colonization was also observed in the noses of normal mice after the same bacterial inoculation, but not apparently in the lower respiratory tract. These results suggest that pneumococcal infection may develop from the upper to the lower respiratory tract as a possible sequence preferentially in influenza virus-infected subjects.

Identification of IFN-gamma-producing cells in IL-12/IL-18-treated mice

Both IL-12 and IL-18 have been characterized as effective IFN-gamma-inducing cytokines. Concomitant treatment with IL-12 and IL-18 has been shown to synergistically induce IFN-gamma and may be an effective therapy for treating cancer, allergy, and infectious diseases. To understand the mechanisms underlying the strong induction of IFN-gamma by IL-12/IL-18 in mice, we focused our studies on the IFN-gamma-producing cells in various lymphoid organs and tissues and utilized the intracellular cytokine staining method to detect such cells in situ. After combined treatment with IL-12 and IL-18, IFN-gamma-positive cells in C57BL/6 mice were detected in the liver (12.18%), spleen (0.68%), bone marrow (1.80%), and peritoneum (2.12%), but not in the thymus or lymph nodes (<0.05 and <0.08%, respectively). A two-color staining method revealed that the majority of IFN-gamma-producing cells in the liver were NK1.1(+) cells, while those in the spleen were mostly CD3(+) cells, and to a lesser degree NK1.1(+) cells. Both CD4(+) and CD8(+) cells in the liver and in the spleen produced IFN-gamma. The CD19(+) B cell population was not definitely shown to produce IFN-gamma in our induction experiments. NKT cells, which are a subpopulation of NK1. 1(+) CD3(+) cells, were diminished in the liver and did not seem to contribute to IFN-gamma production arising from IL-12/IL-18 treatment. Further in vitro experiments confirmed the responsiveness of hepatic mononuclear cells to IL-12/IL-18 stimulation. This study is the first to show the IFN-gamma-producing mechanisms of IL-12/IL-18 treatment at the phenotypic level.