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Biomedical subjects

H Iwata

Publications and source records attributed to H Iwata.

At least 181 records · Page 10Linked to original sources
PubMed1999

Control of complement activities for immunoisolation.

Immunoisolation of cells by semipermeable membranes is a most promising approach to transplant xenogeneic cells. Although membranes which allow xenotransplantation have been reported, ambiguity remains as to their long term effectiveness. In this review, we would like to reconsider the immuno-isolative effectiveness of membranes reported from the standpoint of permeability and present our strategy to prepare membranes that can realize long-term functioning of xenograft. There are distinct different types of semi-permeable membranes, hydrogel membranes and ultrafiltration membranes. Studies on their permeability indicated that neither of these membranes effectively fractionate solutes on the basis of molecular size under a diffusion-controlled process, nor thus can they immuno-isolate xenograft for a long time. Humoral immunity including antibodies and complement proteins is suspected of playing a major role in the rejection of xenografts. Control of complement cytolytic activities, not antibody permeation, may be a key factor determining the fate of the xenograft enclosed in membranes. We found that the microbead containing poly(styrene sulfonic acid) can consume complement cytolytic activities and thus can effectively protect xenogeneic islets of Langerhans in diabetic mice from the humoral immunity.

Animals↗
PubMed1999

Serial changes in the rate of proteoglycan synthesis after chemonucleolysis of rabbit intervertebral discs.

STUDY DESIGN: Serial changes in the rate of proteoglycan synthesis in rabbit discs after chemonucleolytic treatment with chymopapain and chondroitinase ABC were measured using an in vitro method. OBJECTIVES: To determine the retained ability of the intervertebral disc to synthesize proteoglycans after chemonucleolytic treatment. SUMMARY OF BACKGROUND DATA: Most previous studies describe radiologic and histologic changes that occur after chemonucleolytic treatment. However, in humans it is not clear whether reconstitution of the disc space with normal nucleus proteoglycans can occur with time. METHODS: Twenty-five rabbits were treated with chymopapain (10 units/0.1 mL/disc) and chondroitinase ABC (5 units/0.1 mL/disc) by intradisc injection. Five rabbits were killed at each interval, 1, 2, 4, 8 and 12 weeks after injection. Radiologic changes in the disc height were noted, and the rate of proteoglycan synthesis was determined biochemically. RESULTS: After injection, no significant recovery of disc height was seen in either enzyme group after the initial disc narrowing. The average rate of proteoglycan synthesis in control rabbit intervertebral discs, those which had not been surgically treated, was 27.1 (x 10(-6) mmols sulphate/hour/dry weight). Twelve weeks after injection, the values were 21.6 in the saline group, 8.9 in the chondroitinase ABC group, and 8.2 in the chymopapain group. CONCLUSIONS: Doses within the therapeutic range can damage disc cells, at least in the rabbit, so that proteoglycan synthesis declined to 30% of control rates, and no significant recovery of disc height was observed.

Animals↗
PubMed1999

Bioadhesion of gelatin films crosslinked with glutaraldehyde.

The present study was carried out in an attempt to make a gelatin film strongly bioadhesive by introducing free dangling aldehyde groups. When gelatin films were treated with 0.5M of glutaraldehyde (GA) solution at 60 degrees C, free aldehyde groups (up to 150 micromol/g) were introduced in the film. The bonding strength of GA-crosslinked gelatin films (GA gelatin films) with biological tissue was assessed using porcine skins. It was found that bonding strength increased with increasing aldehyde content in the film. The GA gelatin films had bonding strength as high as 250 gf/cm2 whereas the native gelatin film (before GA treatment) showed bonding strength of 40 gf/cm2. When the aldehyde groups introduced in the gelatin films were quenched with glycine or reduced by NaBH4, the films no longer demonstrated such high bonding strength. These facts suggest that a Schiff base was formed between the free dangling aldehyde in the GA gelatin films and the amino groups of the natural tissue, which strongly contributed to a marked bioadhesion.

Adhesives↗
PubMed1999

Relationship of matrix metalloproteinases and their inhibitors to cartilage proteoglycan and collagen turnover: analyses of synovial fluid from patients with osteoarthritis.

OBJECTIVE: To determine the relationship between matrix metalloproteinases (MMPs), their inhibitors, and the turnover of matrix molecules in articular cartilage from patients with osteoarthritis (OA). METHODS: Synovial fluid samples were collected from the knees of 54 patients with OA. Radiographic evaluations and magnetic resonance imaging were performed on the knees of 34 OA patients to classify the stage of the disease. Biochemical analyses and immunoassays were used to measure the concentrations of MMP-1, MMP-3, tissue inhibitor of metalloproteinases 1 (TIMP-1), TIMP-2, the disaccharide of hyaluronic acid, the proteoglycan glycosaminoglycan disaccharides of chondroitin 4-sulfate (delta di-CS4) and chondroitin 6-sulfate (delta di-CS6), the 846 epitope on chondroitin sulfate of cartilage proteoglycan aggrecan (putative biosynthetic marker), the keratan sulfate (KS) epitope of aggrecan (putative degradation marker), and the C-propeptide of cartilage type II procollagen (CPII) (biosynthetic marker). RESULTS: The concentration of TIMP-1 was directly correlated with the levels of MMP-1 and MMP-3 (both were also correlated with each other), confirming earlier results. There was an inverse correlation between the delta di-CS6:delta di-CS4 ratio and the concentration of MMP-3. The level of delta di-CS6 was correlated with that of the KS epitope, and to a lesser degree, with that of the 846 epitope (the latter was also correlated with the level of delta di-CS4). The concentration of TIMP-1 correlated with that of the 846 epitope, whereas TIMP-2 levels correlated with those of CPII. There were significantly lower concentrations of delta di-CS6, delta di-CS4, the 846 epitope, and CPII in synovial fluid from patients with late-stage OA. CONCLUSION: These observations suggest a link between proteolysis and inhibitor concentrations in OA cartilage. Production of TIMPs appears to be individually linked to the synthesis of specific cartilage molecules. The reduction in the amount of cartilage-matrix structural components suggests that there is a measurable loss of cartilage in the late stages of the disease, as suggested previously. The resultant composition of the cartilage suggests that the loss may primarily involve "resident" molecules originally present in healthy cartilage.

Aged↗
PubMed1999

Predictability of dielectric properties for ischemic injury of the skeletal muscle before reperfusion.

OBJECTIVE: The purpose of this study is to assess whether or not dielectric properties could predict the severity of ischemic injury of the skeletal muscle before reperfusion to prevent the myonephropathic metabolic syndrome (MNMS). METHODS: Japanese White rabbits were anesthetized and their hind limbs were subjected to 0, 2, 4, and 6 h of ischemia and then 10 h of reperfusion (n = 4, 5, 6, and 6). Dielectric properties of the gastrocnemius muscle were measured and tan delta(m) and D were calculated from them. To assess ischemic injury, we also measured (a) creatine phosphate kinase (CPK) and aldolase, (b) spectrophotometric assay of triphenyltetrazolium chloride assay, and (c) histological evaluation by H & E staining, 10 h after reperfusion. RESULTS: The tan delta(m) increased and D decreased significantly compared with those in preischemia (P < 0.01). The tan delta(m) value just before reperfusion significantly correlated positively with the maximum value of CPK (CPK(max)) or the maximum value of aldolase (ALD(max)) (r = 0.73, 0.69) and negatively with %TTC (r = 0.66). The D value just prior to reperfusion significantly correlated negatively with CPK(max) and ALD(max) (r = 0.81, 0.86) and positively with %TTC (r = 0.79) after reperfusion, respectively. Histologically, skeletal muscle necrosis was detected in 11 out of 12 skeletal muscles with tan delta(m) values which were 3.70 or more and 11 out of 14 muscles with D values which were 1.47 or less. CONCLUSION: The severity of skeletal muscle ischemic injury can be evaluated before reperfusion by measuring the dielectric properties during ischemia.

Animals↗
PubMed1999

Bone scintigraphy and magnetic resonance imaging after transtrochanteric rotational osteotomy.

OBJECTIVE: To assess the ability of bone scintigraphy and magnetic resonance imaging (MRI) to predict the outcome of transtrochanteric rotational osteotomy (TRO) for osteonecrosis of the femoral head (ONFH). DESIGN: This study was a prospective evaluation of imaging techniques. PATIENTS AND METHODS: MRI and bone scintigraphy were performed on 20 hips in 18 patients at 3 months after TRO. The radiographic findings at 3 months after TRO, and the MRI and bone scintigraphic findings, were compared with the radiographic findings at final follow-up (mean 39 months). RESULTS AND CONCLUSIONS: On MRI a low-intensity area or a low-intensity band in the new weight-bearing area extending over the acetabular edge on T1-weighted images was related to the presence of collapse on the radiographs at final follow-up. In hips with an area of absent activity in the new weight-bearing surface on bone scintigraphy, collapse was seen more frequently on radiographs at final follow-up than in hips without this feature. Bone scintigraphy was no more specific than radiography in predicting the outcome after TRO. We consider MRI to be superior to bone scintigraphy in predicting the occurrence of collapse, which is one of the major short-term problems after TRO.

Adult↗
PubMed1999

Osteonecrosis of the femoral head associated with pregnancy.

A 31-year-old pregnant woman suddenly complained of bilateral hip pain 2 weeks before delivery. She was delivered of triplets by Caesarean section. She had been treated with human menopausal gonadotropin and human chorionic gonadotropin (hMG-hCG) before pregnancy. Radiograms of the hip joint showed collapse of the femoral heads bilaterally. Magnetic resonance imaging revealed a band pattern of low signal intensity for both hips on T1- and T2-weighted images. She had no history of steroid therapy or alcohol abuse. Osteonecrosis of the femoral heads bilaterally associated with pregnancy was confirmed. Pathology of the femoral head showed typical empty lacunae and necrosis of the trabecula.

Adult↗
PubMed1999

Effects of recombinant human erythropoietin on thrombosis and fibrinolysis in autologous transfusion for hip surgery.

Recombinant human erythropoietin (rHuEPO) is effective in allowing autologous blood donation in patients unable to donate because of anemia. As adverse effects of rHuEPO might include activation of coagulation and possibly fibrinolysis, we investigated these possibilities in the context of autologous blood donation preceding hip surgery. Thirty-seven patients who donated 800 ml of autologous blood for elective hip surgery were randomly assigned to either a group of 20 receiving preoperative treatment with rHuEPO (erythropoietin beta), 6000 U i.v. twice weekly for 3 weeks, or an untreated control group of 17. A significant increase in platelet count was associated with autologous blood donation and intraoperative blood loss with or without rHuEPO. Coagulation and fibrinolysis were increased significantly by intraoperative blood loss in both groups, but not by rHuEPO. Coagulation and fibrinolysis were not activated by rHuEPO for elective hip surgery.

Adult↗
PubMed1999

Allopurinol, an inhibitor of xanthine oxidase, improves the development of IVM/IVF bovine embryos (>4 cell) in vitro under certain culture conditions.

To determine the origin of free oxygen radicals in the culture medium of bovine embryos, the effect of allopurinol, an inhibitor of xanthine oxidase, on the development of embryos (>4 cell) in modified synthetic oviduct fluid (m-SOF) medium was examined. When embryos were cultured in the presence of 0.2 mM allopurinol under high oxygen tension (5% CO2 in air), the blastocyst rate significantly (P<0.05) increased compared with the absence of allopurinol (allopurinol (+) 42 vs. (-) 25%; Day 6, 63 vs. 51%; Day 7, 69 vs. 58%; Day 8). However, allopurinol had no effect on embryo development under low oxygen tension (5% CO2, 5% O2, 90% N2). Moreover, it was found that the developmental rate and the total cell number of blastocysts decreased (development rate: 60 vs. 28%, cell number: 132 vs. 74) when the embryos were cultured in medium containing 0.01 U/mL xanthine oxidase (XOD) and 0.1 mM hypoxanthine (HXT), and the damaging effect of XOD and HXT was removed by the addition of 0.2 mM allopurinol. The beneficial effect of allopurinol was also observed when the glucose concentration was increased to 4.5 mM from 1.5 mM (control: 22% vs. allopurinol: 34%; Day 8), but no beneficial effects were observed in the media without glucose (control: 55% vs. allopurinol: 59%). Taken together, these results suggested that a portion of the free oxygen radicals are generated from the XOD and HXT reactions under culture conditions, and this generation is enhanced by high oxygen tension in the gas atmosphere or by high glucose concentrations in the medium.

Allopurinol↗
PubMed1999

Catastrophic failure of cementless total hip arthroplasty using a femoral component without surface coating.

Consecutive series of 90 hips that had had a primary cementless arthroplasty with use of straight collarless stems between January 1988 and September 1992 were reviewed. Twenty-eight hips with Omnifit Normalized Stems (Fit-N) and 45 hips with Omniflex Normalized Stems (Flex-N) without porous coatings were compared clinically and radiographically with 17 hips with Omnifit Microstructured Stems (Fit-M) with porous coating. The average follow-up periods for the 3 stems were 97 months, 73 months, and 93 months. Revision was performed or awaited in 9 cases (32.1%) in the Fit-N group, 18 cases (40.0%) in the Flex-N group, and 1 case (5.8%) in the Fit-M group. The average annual subsidence was 0.62 mm/y, 0.73 mm/y, and 0.17 mm/y. Osteolysis of more than 3 mm occurred in 28.6%, 37.8%, and 23.5%. Fit-N stems and Flex-N stems without porous coatings are not appropriate for cementless total hip arthroplasty.

Bone Cements↗
PubMed1999

Apneustic breathing in children with brainstem damage due to hypoxic-ischemic encephalopathy.

To confirm the presence of apneusis in patients with hypoxic-ischemic encephalopathy and to clarify which factors influence their respiratory patterns, polygraphic studies were performed on two patients. Apneusis was clinically suspected in both patients who had severe brainstem damage. In one subject, inputs of vagal afferents from the gastrointestinal tract and the urinary bladder often resulted in extreme tachypnea instead of apneusis. Lung inflation facilitated expiration during inspiratory arrest. Expiration preceded a periodic inhibition of rigospastic discharge in the right biceps muscle. In the other subject, prolonged inspiratory pauses with cyanosis occurred with or without preceding epileptic seizure. Both phenytoin dose reduction and treatment with tandospirone, a serotonin-1A agonist, were effective in improving the respiratory distress in this subject.

Brain↗
PubMed1999

DNA methylation analysis at distal and proximal promoter regions of the oestrogen receptor gene in breast cancers.

Oestrogen receptor alpha (ER-alpha) gene has two specific promoters, distal (P0) and proximal (P1), which induce almost identical transcripts in size due to different splicing. We examined the methylation at both promoter regions of the ER-alpha gene using HpaII, a methylation-sensitive restriction enzyme, prior to polymerase chain reaction (PCR) amplification. To confirm the results of PCR-based methylation analysis, Southern hybridization was also performed. Twenty of 29 patients with ER-alpha-positive tumours and five of 27 with ER-alpha-negative tumours were unmethylated at the P1 promoter region of the ER-alpha gene. The incidence of methylation was highly negatively correlated with ER-alpha expression (P = 0.0002). A similarly negative correlation was observed at the P0 promoter region of the ER-alpha gene (P = 0.0154). Additionally, the tumours with the ER-alpha gene hypermethylated at both promoter regions had definitely negative ER-alpha values. It was suggested that this epigenetic change might control ER-alpha expression, and might play an important role in the loss of hormone-dependence in breast cancer.

Breast Neoplasms↗
PubMed1999

Presence of telomeric G-strand tails in the telomerase catalytic subunit TERT knockout mice.

BACKGROUND: Telomerase consists of two essential subunits, the template RNA (TR; telomerase RNA) and the catalytic subunit TERT (telomerase reverse transcriptase). Knockout mice with a mTR (mouse TR) deletion have been described and well characterized. However, mice with a mTERT (mouse TERT) deletion have not been reported. RESULTS: mTERT-knockout mice have been constructed. The first generation mTERT -/- mice were fertile, and did not show any noticeable macroscopic or microscopic phenotypic change. All tissue cells derived from mTERT -/- mice that were examined lacked telomerase activity, indicating that mTERT is the only gene encoding the telomerase catalytic subunit. Pulse field gel electrophoresis (PFGE) and nondenaturing in-gel hybridization analyses showed that mouse telomeric DNA has G-strand 5'-overhangs, as demonstrated for human and yeast cells. This telomeric single-stranded G-tail was also observed in MEF (mouse embryonic fibroblast) and liver cells derived from mTERT -/- mice. CONCLUSIONS: mTERT-knockout mice show phenotypes that are apparently normal at least during the early generations. This observation is similar to that obtained with the mTR-knockout mice. The presence of the telomeric G-strand tails in mTERT -/- mice suggests that these telomeric 5'-overhangs are produced by telomerase-independent mechanisms, as has been proposed for yeast and human.

Amino Acid Sequence↗
PubMed1999

Lactic dehydrogenase virus inhibits allergic immunoglobulin E production: in vivo molecular analysis of cytokines.

The effects of lactic dehydrogenase virus (LDV) infection on allergic immunoglobulin (Ig)E production and interleukin (IL)-4 gene expression were studied. LDV infection suppressed antigen-induced IgE production in sensitized mice. The elevations of IL-4 gene expression in spleen and mesenteric lymph nodes 3 and 7 days after ovalbumin challenge were suppressed significantly in LDV-infected mice compared with control mice. The expression of the interferon (IFN)-gamma gene of mesenteric lymph nodes was significantly increased in LDV-infected mice. These results suggest that LDV infection suppressed antigen-induced IgE production by decreasing IL-4 production, and that suppression of IL-4 gene expression may be mediated by a mutual inhibition mechanism between T helper (Th)1 and Th2 cells.

Allergens↗
PubMed1999

Effects of exercise for 1 month on serum lipids in adolescent females.

BACKGROUND: The present study was done to clarify the effects of 1 month of exercise on levels of total cholesterol (TC) and high-density lipoprotein cholesterol (HDLC) and on the ratio TC/HDLC and also to evaluate the relationship of body fat to amount of exercise and TC/HDLC ratio. METHODS: Twenty-seven female athletes (aged 15-18 years) were divided into two groups: the participant's group, in which players trained and attended a tournament, and the non-participant's group, in which players did not attend the tournament. We assessed the amount of exercise, body composition, serum TC and HDLC and TC/HDLC on four occasions: before (T0), during (T1), 1 day after (T2) and a week after (T3) the experimental period. Levels of TC and HDLC adjusted for changes in plasma volume were compared for each occasion. Two multiple regression models for change in TC/HDLC from T0 to T2 and from T0 to T3 were employed. RESULTS: (i) The changing patterns in TC and HDLC throughout the program were different between the two groups; (ii) the decreased level of TC/HDLC after 1 month of exercise may easily revert to its original level; and (iii) the relevant factor for the decline in TC/HDLC was the amount of exercise, not body fat reduction. CONCLUSIONS: Exercise may be a more important factor for the improvement of TC/HDLC than concomitant body fat reduction and non-strenuous exercise may maintain a more stable and higher HDLC level than strenuous exercise.

Adolescent↗