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Biomedical subjects

K Ijiri

Publications and source records attributed to K Ijiri.

At least 19 recordsLinked to original sources
PubMed2005

Delayed segmental motor paralysis following laminoplasty: two case reports.

STUDY DESIGN: Two patients who experienced the onset of segmental motor paralysis several years after laminoplasty are presented. OBJECTIVES: To discuss the mechanism of development of delayed segmental motor paralysis following laminoplasty. SETTING: A department of orthopaedic surgery in Japan. METHODS: One patient experienced motor weakness in his deltoid and biceps muscles on the left side 5 years after laminoplasty. The other patient noticed motor weakness in his deltoid and biceps on the right side 7 years after laminoplasty. CT myelography revealed posterior spur formation and hypertrophic facet joints on the hinged side at the C4-C5 level in both patients. RESULTS: Posterior foraminotomy was performed at the C4-C5 level on the hinged side in both patients. Postoperatively, motor weakness in the deltoid and biceps muscles was improved in both patients. CONCLUSIONS: Although spondylotic changes, including spur formation and disc herniation, have occasionally developed in operated segments after laminoplasty, few patients have required additional surgery for treatment of relapse of neurological deficits. It has been believed that spinal cord is rarely compressed by the spondylotic changes since it shifts posteriorly in the enlarged spinal canal. However, laminoplasty disturbs the facet joints since the medial portion of dorsal cortex and cancellous bone in facet joints is drilled out to make a trough. Facet joints disturbed in this fashion undergo degeneration over time after surgery. Nerve roots may occasionally be compressed by degenerated facet joints and spurs that have developed at the entrance of root canal, resulting in segmental motor paralysis several years after laminoplasty. Careful long-term observation is necessary after this procedure.

Aged↗
PubMed2004

Increased expression of humanin peptide in diffuse-type pigmented villonodular synovitis: implication of its mitochondrial abnormality.

OBJECTIVES: To define the pathogenesis of pigmented villonodular synovitis (PVNS), by searching for highly expressed genes in primary synovial cells from patients with PVNS. METHODS: A combination of subtraction cloning and Southern colony hybridisation was used to detect highly expressed genes in PVNS in comparison with rheumatoid synovial cells. Northern hybridisation was performed to confirm the differential expression of the humanin gene in PVNS. Expression of the humanin peptide was analysed by western blotting and immunohistochemistry. Electron microscopic immunohistochemistry was performed to investigate the distribution of this peptide within the cell. RESULTS: 68 highly expressed genes were identified in PVNS. Humanin genes were strongly expressed in diffuse-type PVNS, but were barely detected in nodular-type PVNS, rheumatoid arthritis, or osteoarthritis. Humanin peptide was identified in synovium from diffuse-type PVNS, and most of the positive cells were distributed in the deep layer of the synovial tissue. Double staining with anti-humanin and anti-heat shock protein 60 showed that humanin was expressed mainly in mitochondria. Electron microscopy disclosed immunolocalisation of this peptide, predominantly around dense iron deposits within the siderosome. CONCLUSIONS: Increased expression of the humanin peptide in mitochondria and siderosomes is characteristic of synovial cells from diffuse-type PVNS. Humanin is an anti-apoptotic peptide which is encoded in the mitochondrial genome. Present findings suggest that mitochondrial dysfunction may be the principal factor in pathogenesis of diffuse-type PVNS and that humanin peptide may play a part in the neoplastic process in this form of PVNS.

Arthritis, Rheumatoid↗
PubMed2004

Primary malignant peripheral nerve sheath tumor of the cauda equina in a child case report.

STUDY DESIGN: A case report of primary malignant peripheral nerve sheath tumor (MPNST) of the cauda equina in a child is presented, and the literature is reviewed. OBJECTIVE: To discuss the problems involved in the treatment of primary intradural MPNSTs. SETTING: A department of orthopaedic surgery in Japan. METHODS: A 4-year-old boy complained of low-back pain radiating to the left calf. MRI revealed an intradural tumor at L3-L5 level. Following laminectomy of L3, L4 and L5, the tumor was removed en bloc. Based on pathological and immunohistological findings, the tumor was diagnosed as an MPNST. RESULTS: Although adjuvant chemotherapy was administered local recurrence and cerebral and spinal metastases of the tumor were found 6 months after the operation. Following additional incomplete removal of the recurrent tumor, radiation therapy was administered. Although recurrent and metastatic tumors disappeared or diminished in size by radiation, tumors increased in size thereafter, despite additional adjuvant chemotherapy. At 21 months after the first operation, he died of pneumonia. CONCLUSIONS: Reported clinical outcomes for patients with primary intradural MPNST are very poor. Although no gold standard for the treatment of tumors has been established yet, surgical removal of tumors combined with postoperative high-dose radiation may be recommended.

Brain Neoplasms↗
PubMed2003

Use of an otolith-deficient mutant in studies of fish behavior in microgravity.

The mutant strain (ha) of medaka (Oryzias latipes) lack utricular otoliths as fry, and some never form otoliths for life. The cross (F1 generation) between the strain having good eyesight and another strain having ordinary eyesight augmented visual acuity of the F1 generation. Crossing the good eyesight strain and ha mutant produced fish having good eyesight and less sensitivity to gravity in the F2 population. Their tolerance to microgravity was tested by parabolic flight using an airplane. The fish exhibited less looping and no differences in degree of looping between light and dark conditions, suggesting that loss of eyesight (in darkness) is not a direct cause for looping behavior in microgravity. The ha embryos could not form utricular otoliths. They did form saccular otoliths, but with a delay. Fry of the mutant fish lacking the utricular otoliths are highly dependent on light upon hatching and exhibit a perfect dorsal-light response (DLR). As they grow, they eventually shift from being light-dependent to being gravity-dependent. Continuous treatment of the fry with altered light direction suppressed this shift to gravity dependence. Being less dependent on gravity, these fish can serve as models in studying the differences expected for the vestibular system of fish reared in microgravity. When these fish were exposed to microgravity (parabolic flights) of an airplane, they spent far less time looping than fish reared in an ordinary light regimen.

Animals↗
PubMed2003

Otolith formation in a mutant Medaka with a deficiency in gravity-sensing.

Mutant Medaka ha exhibit spontaneous mutation that is characterized by frequent inhibition or perturbation in the formation of utricular otoliths and/or semicircular canals. Three major features of otolith morphogenesis were observed in ha strain: 1) The initial appearance of otoliths was delayed, mispositioned, and malformed compared to normal embryos. 2) No utricular otoliths appeared on macula of any ha fry just after hatching. A symmetric state of otoliths was seen only when saccular otoliths were situated on macula in both inner ears. 3) In some fry, formation of utricular otoliths was observed in their later development. However, no new utricular otoliths appeared after fish were seventy or more days old after hatching. These observations show that otolith morphogenesis in ha is very different from that of wild-type. In this study, we classified adult ha into four different phenotypes using the existence or absence of utricular otoliths as our criteria. We concluded that dysfunction of utricular otoliths and semicircular canals cause a defect that affects the gravity-sensing abilities of medaka ha.

Animals↗
PubMed2002

Swimming behavior of larval Medaka fish under microgravity.

Fish exhibit looping and rolling behaviors when subjected to short periods of microgravity during parabolic flight. Strain-differences in the behavioral response of adult Medaka fish (Oryzias latipes) were reported previously, however, there have been few studies of larval fish behavior under microgravity. In the present study, we investigated whether microgravity affects the swimming behavior of larvae at various ages (0 to 20 days after hatching), using different strains: HNI-II, HO5, ha strain, and variety of different strains (variety). The preliminary experiments were done in the ground laboratory: the development of eyesight was examined using optokinetic response for the different strains. The visual acuity of larvae improved drastically during 20 days after hatching. Strain differences of response were noted for the development of their visual acuity. In microgravity, the results were significantly different from those of adult Medaka. The larval fish appeared to maintain their orientation, except that a few of them exhibited looping and rolling behavior. Further, most larvae swam normally with their backs turning toward the light source (dorsal light response, DLR), and the rest of them stayed with their abdomen touching the surface of the container (ventral substrate response, VSR). For larval stages, strain-differences and age-differences in behavior were observed, but less pronounced than with adult fish under microgravity. Our observations suggest that adaptability of larval fish to the gravitational change and the mechanism of their postural control in microgravity are more variable than in adult fish.

Animals↗
PubMed2002

Aquatic animal research in space station and its issues--focus on support technology on nitrate toxicity.

We studied the effects of accumulated nitrate in water on the spawning, hatching and development of medaka using a simple nitrifying filter and a combined filter having both nitrifying and denitrifying capabilities. A nitrate concentration of 100 mg NO3(-)-N/L was clearly of lethal toxicity to fish when they were exposed to nitrate in both adult and the growing phases. A nitrate concentration of 75 mg NO3(-)-N/L reduced the fertilization rate, delayed the hatching time and reduced the hatching rate of the eggs laid by adults and decreased the growth rate of juveniles. In addition, nitrate accumulations as low as 50 mg NO3(-)-N/L remarkably retarded spawning and lowered the number of eggs laid by fish exposed in the juvenile phase. The effects on the reproduction system may be initiated by a low concentration, approximately 30 mg NO3(-)-N/L.

Animals↗
PubMed2001

[Aquatic animals and use of centrifuge in space experiments].

There are some experiments which do not need a centrifuge apparatus in space, however, for other space experiments the use of centrifuge is indispensable as the control. The characteristics of these two types of space experiments are explained. Generally, the more quantitatively the phenomenon is analyzed, the greater the need of centrifuge apparatus becomes. The centrifuge in space can realize various gravity values ranging from 0 to 1 G, and this will extend the present biology to a more universal biology.

Animals↗
PubMed2000

Results of a longer than 10-year follow-Up of patients with rheumatoid arthritis treated by occipitocervical fusion.

STUDY DESIGN: Evaluation of results a longer than 10-year follow-up of patients with upper cervical lesions due to rheumatoid arthritis who underwent occipitocervical fusion. OBJECTIVE: To determine the final outcome of patients with upper cervical lesions due to rheumatoid arthritis treated by occipitocervical fusion. SUMMARY OF BACKGROUND DATA: There are few studies reporting the final outcome of patients with rheumatoid arthritis treated by occipitocervical fusion and observed for longer than 10 years. METHODS: The subjects were 16 patients with rheumatoid arthritis with myelopathy who underwent occipitocervical fusion with a rectangular rod more than 10 years ago. All 16 patients had irreducible atlantoaxial dislocation, and 11 also had vertical dislocation of the axis. All patients had preoperative nuchal pain, and were classified into Class II (two patients), Class IIIA (nine patients), and class IIIB (five patients) according to Ranawat's preoperative neurologic classification. RESULTS: The atlas-dens interval remained the same as immediately after surgery. Vertical dislocation returned to the preoperative condition, despite successful surgical correction. Preoperative occipital pain disappeared or was reduced in all cases. Myelopathy improved in 12 of the 16 patients (75%) by more than one class in the Ranawat preoperative neurologic classification. Survival rate at 10 years after surgery was 38%; mean age at death was 70.7 years. The postoperative periods during which patients could walk by themselves ranged from 6 months to 13 years (mean, 7.5 years). CONCLUSIONS: Occipitocervical fusion for patients with rheumatoid arthritis is useful for decreasing nuchal pain, reducing myelopathy, and improving prognosis.

Aged↗
PubMed2000

Vestibular and visual contribution to fish behavior under microgravity.

Vestibular and visual information are two major factors fish use for controlling their posture under 1 G conditions. Parabolic flight experiments were carried out to observe the fish behavior under microgravity for several different strains of Medaka fish (Oryzias latipes). There existed a clear strain-difference in the behavioral response of the fish under microgravity: Some strains looped, while other strains did not loop at all. However, even the latter strains looped under microgravity conditions when kept in complete darkness, suggesting the contribution of visual information to the posture control under microgravity. In the laboratory, eyesight (visual acuity) was checked for each strain, using a rotating striped-drum apparatus. The results also showed a strain-difference, which gave a clue to the different degree of adaptability to microgravity among different strains. Beside loopings, some fish exhibited rolling movement around their body axis. Tracing each fish during and between parabolas, it was shown that to which side each fish rolls was determined specifically to each individual fish, and not to each strain. Thus, rolling direction is not genetically determined. This may support the otolith asymmetry hypothesis. Fish of a mutant strain (ha strain, having homozygous recessive of one gene ha) have some malfunction in otolith-vestibular system, and their behavior showed they are not dependent on gravity. Morphological abnormalities of their ear vesicles during the embryonic and baby stages were noted. Their eyesight and dorsal light responses were also studied. Progress in the project of establishing a new strain which has good eyesight and, at the same time, being deficient in otolith-vestibular system was reported. Crosses between the strain of good eyesight and ha strain were made, and to some extent, F2 fish have already shown such characteristics suited for living under microgravity conditions.

Animals↗
PubMed2000

Nonsurgically managed patients with degenerative spondylolisthesis: a 10- to 18-year follow-up study.

OBJECT: Controversy exists concerning the indications for surgery and choice of surgical procedure for patients with degenerative spondylolisthesis. The goals of this study were to determine the clinical course of nonsurgically managed patients with degenerative spondylolisthesis as well as the indications for surgery. METHODS: A total of 145 nonsurgically managed patients with degenerative spondylolisthesis were examined annually for a minimum of 10 years follow-up evaluation. Radiographic changes, changes in clinical symptoms, and functional prognosis were surveyed. Progressive spondylolisthesis was observed in 49 patients (34%). There was no correlation between changes in clinical symptoms and progression of spondylolisthesis. The intervertebral spaces of the slipped segments were decreased significantly in size during follow-up examination in patients in whom no progression was found. Low-back pain improved following a decrease in the total intervertebral space size. A total of 84 (76%) of 110 patients who had no neurological deficits at initial examination remained without neurological deficit after 10 years of follow up. Twenty-nine (83%) of the 35 patients who had neurological symptoms, such as intermittent claudication or vesicorectal disorder, at initial examination and refused surgery experienced neurological deterioration. The final prognosis for these patients was very poor. CONCLUSIONS: Low-back pain was improved by restabilization. Conservative treatment is useful for patients who have low-back pain with or without pain in the lower extremities. Surgical intervention is indicated for patients with neurological symptoms including intermittent claudication or vesicorectal disorder, provided that a good functional outcome can be achieved.

Activities of Daily Living↗
PubMed2000

Mutant Medaka fish having a deficiency in otolith-vestibular system and their behavior in microgravity.

Vestibular and visual senses are two major factors fish use for controlling their posture under 1 G conditions. From various studies in the past (parabolic flights and some ground-laboratory experiments), I came to have a hypothesis that "heavily eye-dependent" fish are tolerant to microgravity (micro-G). Theoretically, for "heavily eye-dependent" fish, the following three types may exist. (a) Fish having good eyesight, and having an ordinary sensitivity to gravity, (b) Fish having an ordinary eyesight, and having less sensitivity to gravity, (c) Fish having good eyesight, and having less sensitivity to gravity. In Medaka fish (Oryzias latipes), these three types have successfully been obtained. In this paper, the behavior of such different types of Medaka fish under micro-G will be studied by use of parabolic flights of an airplane. The ground-laboratory experiments are also reported, which focus on the contribution of both vestibular and visual senses to the posture control for each of three types of Medaka fish.

Animals↗
PubMed1999

Retinal photoreceptor and related gene expression in normal and clinostat-treated fish embryos.

Medaka fish had performed mating behavior successfully in space for the first time among vertebrate, and the eggs which were laid in space developed normally, and hatched during the space travel of 15 days aboard the space shuttle in the second International Microgravity Laboratory (IML-2) mission in 1994 (Ijiri 1994). But there has been few studies whether microgravity affects the development of rather complex tissues in this fish. Investigating this problem, we focused on the organogenetic events in the retina in developing Medaka under normal and simulated microgravity conditions (by a three-dimensional clinostat, 3D-clinostat). Our results showed that both normal and 3D-clinostat-treated Medaka embryos developed on almost equal time course. Moreover, we investigated the development of the retina in normal and 3D-clinostat-treated embryos, but there were no differences in organogenesis of their retina. Lamination of retina occurred almost at equal timing and the expressions of opsin genes in the 3D-clinostat-treated group also began almost at the same time as control. Our observations suggest that there were no definite effects of simulated microgravity on the organizations of a complex tissue such as retina in developing fish embryos.

Animals↗
PubMed1999

Application of nitrifying and denitrifying processes to waste management of aquatic life support in space

Since a biological filter with nitrifying bacteria was firstly applied to aquatic animal experiments in IML-2 mission, the reactor system has been further studied to combine both nitrifying and denitrifying reactions under aerobic environment allowing an efficient removal of inorganic nitrogen from animal wastes. The isolated denitrifying bacteria had an activity under aerobic condition with rice straw providing a metabolic carbon source for the reaction. The advantage of the aerobic biological filter having both nitrifying and denitrifying activities may allow to reduce the size of the life support system and also for its manageability. The paper reports characteristics of the biological filter systems used for the IML-2 mission and the improved combined filter system having both nitrifying and denitrifying activities, and discuss its application to space experiments.

Ammonia↗