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Biomedical subjects

K Ejiri

Publications and source records attributed to K Ejiri.

At least 37 records · Page 2Linked to original sources
PubMed1990

Lack of favorable effect of immunomodulators on outbred syngeneic rodent islet transplantation.

We studied the effect of two immunomodulators, lobenzarit disodium and OK-432, on outbred syngeneic islet transplantation. Six hundred fresh islets taken from two male Wistar rats were transplanted intraportally into other male Wistar rats that had been made diabetic with streptozotocin. Lobenzarit was given to 12 recipients and OK-432 to seven recipients intraperitoneally for 1 month, while nine controls received only intraperitoneal saline. Both drug-treated groups could not maintain lower fasting plasma glucose levels or higher fasting body weights at each time as compared with controls. The islet survival time in lobenzarit-treated (23.5 +/- 8.0 days) and OK-432-treated (25.3 +/- 13.4 days) groups was not longer than that (21.6 +/- 9.4 days) of the control group. All the pancreatic insulin contents of the seven surviving controls, ten surviving lobenzarit and five surviving OK-432 recipients were less than 0.8% of the mean insulin content obtained from 12 normal male rats. The hepatic insulin content of both drug-treated groups was not higher than that of the control group. These results suggest that lobenzarit disodium and OK-432 cannot protect outbred syngeneic islet grafts.

Adjuvants, Immunologic↗
PubMed1990

Possible involvement of cholinergic nicotinic receptor in insulin release from isolated rat islets.

Insulin release is influenced by the autonomic nervous system. Regarding parasympathetic control, previous reports have shown that regulation of insulin release is executed exclusively through muscarinic receptors in the pancreatic islets. In the present study, however, we examined the effect on insulin release at the islet level of various agents affecting the parasympathetic nervous system, especially nicotinic receptor blockers. Pancreatic islets isolated from adult Wistar male rats were incubated with these agents and insulin release in the media was measured. Acetylcholine chloride (10(-5) M), as well as distigmine bromide (10(-6), 10(-5) M), both of which are cholinesterase inhibitors, stimulated insulin release, whereas atropine (5 x 10(-6), 5 x 10(-5) M) suppressed it. On the other hand, serum and IgG from myasthenia gravis patients, containing anti-acetylcholine receptor antibodies, affected insulin release, and alpha-bungarotoxin (10(-9)-10(-7) M), a nicotinic receptor blocker, stimulated insulin release dose-dependently. The present observations suggest that insulin release is influenced by the parasympathetic nervous system, mediated via not only muscarinic but also nicotinic receptors.

Acetylcholine↗
PubMed1990

Photodynamic therapy for early gastric cancer using a pulsed gold vapor laser.

Endoscopic photodynamic therapy (PDT) using a pulsed gold vapor laser (wavelength 628 nm, LaserSonics Inc.) was performed on eight cases of early gastric cancer. Three patients refused to have surgery, and the others were in a high-risk group due to old age or complications with other diseases. Hematoporphyrin derivative (HpD I, 2.5-3 mg/kg, Photofrin Inc.) was injected intravenously, and 48-72 hours later, the entire cancer lesion and 5 mm width mucosa encircling it were irradiated with a gold vapor laser through a single quartz fiber. The irradiation was delivered at 300-330 mW for 5-20 minutes, which gave about 90 J/cm 2 dosage. In seven of eight cases, local cure was achieved. Recurrence was noted only in one patient. In one of eight patients, operation was carried out 1 month after PDT. Pathological examination of the resected stomach revealed that the effect of PDT extended into the tunica muscularis propria. Side effects of HpD, such as skin rash, were noted in two patients, but no serious complications of PDT were encountered. This suggests that PDT with a pulsed gold vapor laser is clinically useful in the treatment of early gastric cancer.

Adult↗
PubMed1990

Cerebral hemodynamics in patients with chronic obstructive carotid disease by rCBF, rCBV, and rCBV/rCBF ratio using SPECT.

To evaluate cerebral hemodynamics, 21 patients with chronic occlusion or severe stenosis of the internal carotid or middle cerebral artery with normal or only lacunar infarction on x-ray CT were studied using single photon emission computed tomography (SPECT). We measured rCBV with 99mTc erythrocytes after rCBF with 133Xe, and calculated rCBV/rCBF. rCBF and rCBV of the 25 affected hemispheres were classified as (a) patients with normal rCBF [type I (n = 7) and type II (n = 3)]; (b) patients with decreased rCBF [type III (n = 6) and type IV (n = 9)]. These two groups then could be subdivided according to findings of rCBV, normal, and increased blood volumes. rCBV/rCBF increased as the cerebral perfusion pressure dropped from type I to type III. In type IV, other situations but cerebral autoregulation could be assumed. rCBV/rCBF signifies vascular mean transit time. Type III (high rCBV/rCBF) assumed as the increased OEF, misery perfusion as reported in PET. We propose rCBF, rCBV and rCBV/rCBF using SPECT can be an index for cerebral circulatory reserve.

Arterial Occlusive Diseases↗
PubMed1989

Effect of cooling rate on insulin release from frozen-thawed dispersed rat islet cells.

Rat islet cells, dissociated with EDTA-Dispase, were immersed in 10% dimethyl sulfoxide at 20 degrees C for 15 min and frozen to -40 degrees C at a cooling rate of 0.5 or 1.0 degree C/min and subsequently further to -80 degrees C at 3 degrees C/min by a programmable freezer. After being maintained at -80 degrees C for 10 min, they were rapidly thawed in a water bath at 37 degrees C. They were cultured for 12 h and preincubated in 3.3 mM glucose-containing Krebs-Henseleit bicarbonate buffer (KHBB) for 1 h. Groups of 10(4) cells were then incubated in 3.3 or 16.7 mM glucose-containing KHBB for another hour. As a control, non-frozen-thawed cultured islet cells were incubated similarly. The non-frozen rat islet cells released 1.29 pg insulin/cell.60 min in the presence of 3.3 mM glucose and this release level was significantly elevated to 1.64 pg insulin/cell.60 min in the presence of 16.7 mM glucose. The cells frozen at 0.5 degree C/min releasing 1.55 pg insulin/cell.60 min in the presence of 3.3 mM glucose also responded to 16.7 mM glucose and released the significantly high level of 1.87 pg insulin/cell.60 min. However, the islet cells frozen at a cooling rate of 1 degree C/min secreted 1.74 and 1.92 pg insulin/cell.60 min in the presence of 3.3 mM and 16.7 mM glucose respectively. There was no significant difference between these levels. These results indicate that cryopreservation at a cooling rate of 0.5 degree C/min may be adequate for the preservation of dispersed pancreatic endocrine cells.

Animals↗
PubMed1989

Effect of dimethylthiourea on syngeneic rodent islet transplantation.

We studied the effects of a hydroxyl radical scavenger, dimethylthiourea (DMTU), on syngeneic islet grafts. Six hundred fresh islets taken from two Wistar rats were transplanted intraportally into other Wistar rats made diabetic with streptozotocin. DMTU was given to five recipients intraperitoneally for a month while nine controls received only intraperitoneal saline. The DMTU-treated group had significantly lower fasting plasma glucose levels at 1.5, 4.5, 5, 5.5, 6, 7, 9 and 11 weeks and had higher mean fasting body weights between the 2.5th week and their eventual sacrifice. Their islets also survived significantly longer than did those of the controls (73.6 +/- 3.4 vs. 21.6 +/- 9.4 days). This suggests that oxygen free radical production endangers graft survival and that the hydroxyl radical scavenger DMTU protects syngeneic islet grafts.

Animals↗
PubMed1989

Sophisticated mesh filtration technique of a large-scale isolation of islets and their function.

A large-scale isolation of islets is required for islet transplantation. We improved our conventional method, and could obtain about three times more islets than by the conventional methods. Pancreata of adult Wistar rats were inflated by injection of buffer with (A) or without 1.3 mg/ml collagenase (B). The rats were bled from the inferior vena cava and the aorta in (A) simultaneously with the inflation. They were further digested with collagenase and filtered through two different meshes (pore size: 1190 and 590 microns) (A1) or three different meshes (pore size: 1190, 590 120 microns) (A2) in order. Insulin released from islets isolated in this manner was determined by 1-h incubation with 3.3 and 16.7 mM glucose. Besides, 600 islets each were transplanted into the liver of streptozotocin-induced diabetic Wistar rats and their fasting plasma glucose was measured at weekly intervals. (1) With these methods more numerous islets were harvested by A1 (mean: 554) and A2 (mean: 746) than B (mean: 224). (2) Insulin released at both glucose concentrations was similar among islets obtained by A1, A2 and B. (3) The plasma glucose-lowering effect was similar among the islets obtained by these methods. (4) A more selected range of islet sizes was obtained by A2 than A1. These observations indicate that the present techniques (A1 and A2) are less time-consuming and simpler for a large-scale isolation of islets.

Animals↗
PubMed1989

Islet function after storage at -2 degrees C and -196 degrees C.

The radical treatment of type 1 diabetes by transplantation requires the extracorporeal storage of islets, and this has frequently been studied. Damage from ice formation, however, has prevented the development of any satisfactory method for preservation. We compared islet function after frozen storage with that after non-frozen storage. Isolated rat islets immersed in 10% dimethyl sulfoxide were kept at -2 degrees C (group A) and -196 degrees C (group B) for 7 days. After one day of culture, some of the islets were incubated in 3.3 and 16.7 mM glucose-containing Krebs--Henseleit bicarbonate buffer for 60 min. The other islets were incubated with 3H-leucine for 2 h. The radioactivity of whole-islet homogenate and the insulin extracted from it were measured. We also counted the number of islets before and after the 7-day storage. The islets thus preserved were transplanted into streptozotocin-induced diabetic rats and the fasting plasma glucose was determined weekly. Non-cooled islets were used as controls (group C). Insulin release in the presence of 16.7 mM glucose did not significantly differ between groups C and A, whereas it was lower in group B than in groups A or C. The islet uptake of 3H-leucine was lower in A and B compared with C, but the insulin synthesis was similar in all three groups. More islets were recovered from A than B. Fasting plasma glucose was lowered similarly in the diabetic rats after transplantation of islets from A and B. The relative ease of preservation at -2 degrees C, and the positive results of this experiment, favor this method of preservation.

Animals↗
PubMed1989

Production of anti-insulin monoclonal antibody and its application to immunoassay of insulin and immunohistochemistry.

An unlimited supply of suitable antisera is wanted for immunoassays, analysis of antigenic determinants and precise localization of antigens in biological systems. Therefore, we produced a monoclonal antiporcine insulin antibody by the hybridoma technology and assessed it in comparison with polyclonal antibody. The spleen cells of BALB/c mice immunized against porcine insulin were hybridized with mouse myeloma cells (P3-X63-Ag8-U1). The monoclonal antibody thus generated was shown to have high binding capacity and specificity to porcine insulin in radioimmunoassay. It reacted with human insulin as well, but did not crossreact with other polypeptide hormones produced in the pancreatic islets such as glucagon, somatostatin and pancreatic polypeptide. In immunohistochemistry human and dog islets were stained by this monoclonal antibody. Rat islets were not stained, although they reacted with polyclonal anti-insulin antibody. The insulin of human serum samples measured using the monoclonal antibody was tightly correlated with that using the polyclonal antibody. These observations indicate that our hybridoma-derived monoclonal antibody is useful for immunoassay as well as localization of insulin.

Animals↗
PubMed1989

Participation of nicotinic receptor in hormone release from isolated rat islets of Langerhans.

Pancreatic hormone release is generally thought to be regulated through adrenergic as well as muscarinic receptors. We have previously observed possible nicotinic involvement in insulin release. In the present study, we incubated isolated rat islets for 60 min with various concentrations of atropine (a muscarinic receptor blocker), alpha-bungarotoxin (alpha-Btx, a nicotinic receptor blocker), and anti-acetylcholine receptor antibody (IgG) (anti-Ach.R.Ab) obtained from a patient with myasthenia gravis. Atropine suppressed insulin release, and alpha-Btx and anti-Ach.R.Ab potentiated it; atropine did not suppress glucagon release, while alpha-Btx and anti-Ach.R.Ab raised it. None of these agents influenced somatostatin release. These observations suggest that muscarinic as well as nicotinic receptors influence insulin release, as nicotinic receptors do glucagon release. Neither nicotinic nor muscarinic receptors seem to regulate somatostatin release.

Acetylcholine↗
PubMed1989

Vacor inhibits insulin release from islets in vitro.

It has been reported that Vacor, a rodenticide containing N-3-pyridylmethyl-N'-p-nitrophenyl urea, causes insulin-dependent diabetes mellitus. The pathomechanism of Vacor-induced diabetes mellitus has not been clarified yet. The effect of Vacor, therefore, was studied in terms of insulin release from isolated rat pancreatic islets. Vacor suppressed glucose-stimulated insulin release, but did not affect the insulin release induced by theophylline or 12-o-tetra-decanoylphorbol 13-acetate. It is suspected that the suppression of insulin release from pancreatic islets by Vacor may contribute to the pathogenesis of Vacor-induced diabetes mellitus and that this suppression might not be related to cAMP and C-kinase.

Animals↗
PubMed1989

Production of anti-insulin monoclonal antibody and its clinical application.

Hybridoma-produced monoclonal antibody (MoAb) against insulin is useful for insulin assays because of its specificity and plentiful supply. The spleen cells of male BALB/c mice immunized against monocomponent porcine insulin were hybridized with mouse myeloma cells (P3-X63-Ag8-U1). The resulting anti-insulin antibody (Ab) was purified and characterized by radioimmunoassay (RIA) using 125I-porcine insulin and sandwich-method enzyme immunoassay (EIA) using Ab-conjugated beads and beta-galactosidase. For reference, we used anti-insulin polyclonal antibody raised in guinea pigs (PoAb). Using the Ouchterlony technique, we identified the antibody as being of subclass IgG 1. We judged this antibody to be MoAb because it did not react at all with porcine insulin during EIA, in concentrations between 0 and 12.5 ng/ml; in contrast, PoAb reacted dose-dependently. During RIA, this Ab did not cross-react with glucagon, somatostatin or pancreatic polypeptide. It did cross-react with human and bovine insulins but not with rat insulin. The proper concentration of this MoAb for RIA proved to be 1:1,500,000 and the smallest detectable level of porcine insulin by RIA using this Ab was 0.5 ng/ml. These levels were similar to those obtained with PoAb. The binding activity of this MoAb to human insulin was quite similar to that of porcine insulin. RIA insulin determinations using our MoAb correlated well with those employing PoAb.

Animals↗
PubMed1989

[Evaluation of cerebral hemodynamics by 123I-IMP in cerebral AVMs before and after operation by using SPECT].

To evaluate cerebral hemodynamics by N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) preoperative and postoperative (after 1 day, and after 7-10 days) regional cerebral blood flow scan, 6 arteriovenous malformations (AVMs) which performed total removal operations were studied by using a ring type SPECT "HEADTOME". We performed the dynamic scan just after the intravenous injection of 222 MBq (6 mCi) of 123I-IMP, then the static scan 20 minutes after the intravenous injection. In preoperative dynamic scans of all cases, only the first frame image showed the increased activity on the nidus probably because of the blood pool. Preoperative static scans of all cases showed the remarkable decreased activity on the nidus, and decreased activity surrounding the nidus probably because of the peripheral steal phenomenon. In postoperative scan of the next day, 4 out of 6 cases showed the transient decreased peripheral steal, particularly 2 out of those 4 cases showed the transient hyperperfusion probably because of the normal perfusion pressure breakthrough (NPPB). And, 2 out of 6 cases showed transient peripheral low perfusion on much larger area than those of the preoperative scans probably because of the focal brain damages and edemas. We conclude that 123I-IMP SPECT on AVM is very useful to decide the indication of the removal operation, and to estimate the postoperative risk, and to evaluate the preoperative and postoperative cerebral hemodynamic changes in the peripheral area of AVM.

Adolescent↗
PubMed1989

[SPECT measurement of cerebral hemodynamics in transient ischemic attack patients--evaluation of pathogenesis and detection of misery perfusion].

To evaluate the cerebral hemodynamics and the pathogenesis by regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV), 42 transient ischemic attack (TIA) patients and 9 normal volunteers were studied using SPECT. We classified these patients into Group A (n = 23: no occlusion or stenosis of the internal carotid or middle cerebral artery; non large vessel disease) and Group B (n = 19: chronic occlusion or severe stenosis of the internal carotid or middle cerebral artery; large vessel disease). We obtained rCBF with 133Xe inhalation and rCBV with 99mTc-red blood cells. Of 9 normal volunteers aged 43-70 yr (mean age 59.8 +/- 8.3 yr), the mean rCBF was 45.8 +/- 5.1 (ml/100 g brain/min), the mean rCBV was 4.0 +/- 0.4 (ml/100 g brain). The examination was done by comparing the values of the affected hemispheres of Group A and Group B patients with the mean rCBF and the mean rCBV of normal volunteers. Eleven out of Group A patients and 15 out of Group B patients showed decreased rCBF. But of those patients, no patients of Group A showed increased rCBV and 6 out of 19 Group B patients showed increased rCBV. Thromboembolic mechanism which is of Group A patients and Group B patients without increased rCBV, and hemodynamic mechanism which is of Group B patients with increased rCBV were considered as the main cause of TIA. Decreased rCBF and increased rCBV in Group B patients can be assumed as the misery perfusion as reported in PET studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Evaluation of cryopreservation techniques of pancreatic fragments and islets in vitro and in vivo.

We evaluated cryopreservation techniques for pancreatic fragments and islets using rat tissue. After equilibration in 10% dimethyl sulfoxide (Me2SO), the tissue was frozen in a programmable freezer at 1 degree C/min down to -40 degrees C and at 3 degrees C/min down to -71 degrees C. The islets, when thawed, released abundant insulin in the presence of as little as 3.3 mM glucose, much more so than non-frozen islets did. Three additional procedures, prefreezing and post-thawing culture and the stepwise dilution of the Me2SO, lowered the non-specific insulin release of the thawed islets and improved their insulin response to 16.7 mM glucose. Thawed pancreatic fragments subjected to these additional procedures, transplanted into the peritoneal cavity of streptozotocin-induced diabetic rats, reduced their hyperglycemia significantly. The thawed fragments and islets did not differ from their corresponding non-frozen controls in 3H-leucine incorporation. The maintenance of tissue function was not satisfactory. However, our observations indicate that culturing pancreatic tissue before freezing and after thawing and the stepwise dilution of the cryoprotective agent reduce the damage induced by freezing the tissue.

Animals↗
PubMed1988

Complements in diabetes mellitus: activation of complement system evidenced by C3d elevation in IDDM.

To characterize insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) in terms of the complement system, some components of the system as well as the related substances and indices were studied. CH50, C3, C4 and C3bINA significantly increased in both IDDM and NIDDM compared with non-diabetic healthy controls. ACH50 was also elevated in NIDDM, whereas it was similar in IDDM and controls. Besides, the serum concentration of C3d, a breakdown product of C3, was higher in IDDM than in NIDDM and healthy controls, but that in NIDDM did not differ significantly from the control. B1Hg1 was not different among IDDM, NIDDM and non-diabetic controls. These observations suggested that there is a high level of complements in both types of diabetes mellitus, but the complement activation seems to be much enhanced in IDDM compared with NIDDM.

Complement Activation↗