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Biomedical subjects

N Imai

Publications and source records attributed to N Imai.

At least 127 records · Page 7Linked to original sources
PubMed1991

[Study on reconstruction of the anterior cruciate ligament in the monkey knee using polyester artificial ligament].

We performed an experimental study of ACL reconstruction utilizing polyester artificial ligament(Leeds-Keio). The quality of regenerated ligaments was compared between two different procedures; in the one 1 cm wide Leeds-Keio ligament was used alone for reconstruction(Group 1) and in the other, Leeds-Keio ligament of the same size was augmented with one-third width of free patellar tendon (Group 2). Eighteen knees of nine Japanese monkeys were used. The specimens were obtained at 2, 6 and 12 months after the operation and investigated macroscopically, microscopically and biomechanically. Regenerated ligaments in Groups 1 and 2 appeared identical and grossly normal. However, more mature and stable ligament was noted in the cylinder of artificial ligaments after 2 months after operation in Group 2 than in Group 1 in terms of both quality and quantity. Biomechanically, however, the maximum the tension in the regenerated ligaments was approximately 1/2-1/3 of that of normal ACL. The authors believe that more mature ligament was made in ACL reconstruction when the artificial ligament was augmented with autogenous soft tissue.

Animals↗
PubMed1991

Autogenous meniscus grafts in articular cartilage defects--an experimental study.

Many methods have been attempted to repair defects in the articular cartilage involving the subchondral bone, but no satisfactory method has yet been established. We performed an experimental study utilizing autogenous meniscus grafts for defects in the articular cartilage involving the subchondral bone. Sixty-two knees of 31 rabbits were thus treated. Gross and histological examinations were performed in animals sequentially sacrificed after 2 to 24 weeks. In gross examinations, the articular surface was smooth and the degenerative changes were slight although the grafted area appeared as a piece of whitish meniscus in all experimental knees. Histologically, 12 weeks were necessary for complete union in the superficial zone of the junction between the grafted meniscus and the subchondral bone. However, the junction in the deep zone was completely united after two weeks. Degenerative changes, such as fibrillation or ulceration were not noted on the surface of the grafted meniscus. The chondrocytes of the meniscus survived for as long as 24 weeks. The autogenous meniscus graft appears to be a promising alternative for defects in the articular cartilage.

Animals↗
PubMed1991

[Pathogenesis of ipsilateral hemiparesis in patients with lateral medullary syndrome].

Lateral medullary syndrome is known to cause hemiparesis ipsilateral to the medullary lesion. However, it's clinical significance has not been fully evaluated. In this study, we made clinical and angiographic studies in patients with syndrome to elucidate the pathogenesis of ipsilateral hemiparesis. Thirty-four patients with cerebral infarction presenting with this syndrome were studied. Their mean age was 51 years and all the patients were examined within 6 months of their first attack. Diagnosis of ipsilateral hemiparesis was made if subjective feeling of weakness in the upper and lower extremities was associated with increased deep tendon reflexes. Ipsilateral hemiparesis was observed in 38% of all the patients. Cerebral angiography was performed in 26 patients and divided into two groups; group A with ipsilateral hemiparesis (n = 9) and group B without ipsilateral hemiparesis (n = 7). In 56% of patients in group A, angiography showed non-visualization of ipsilateral vertebral artery (VA) and posterior inferior cerebellar artery (PICA). Non-visualization of these two arteries never occurred in the patients of group B. On the other hand, non-visualization of VA alone was observed in 35% of the patients in group B, but it was none in the patients of group A. However, there were no differences in concerning the frequency of non-visualization of PICA alone or non-occlusion at all between both groups. Therefore, the focal ischemia in the region below the pyramidal decussation due to the occlusion of both VA and PICA, regardless of thrombotic or embolic episode, was considered to be responsible for ipsilateral hemiparesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[A case of chondroblastoma originating from the right 6th rib].

Chondroblastomas are rare neoplasms, and comprise 0.5-1% of histologically proved primary bone tumors. We report a case of the tumor originating form the right 6th rib. The patient, a 15-year-old female, was admitted because the abnormal shadow was found on routine chest X-ray film. It was suspected to be the posterior mediastinal tumor based on the chest X-ray, CT and MRI. In surgery, the tumor was 4.0 x 4.0 x 2.5 cm in size and fixed on the rib, but not invasive to other tissue. The content was rough and soft granuloma like. Histological examination confirmed the diagnosis of chondroblastoma of the rib. The patient is doing well without symptoms of recurrence fifteen months after surgery.

Adolescent↗
PubMed1991

[A case of intrathoracic perineurial cyst].

A 67-year-old man was referred to our surgical clinic for evaluation of an abnormal shadow on the chest X-ray examination. CT scan and MRI revealed a tumor in the posterior mediastinum and destruction of the pedicle and intraspinal invagination by the tumor. The tumor in a paravertebral area are linked with a vertebral canal through a destructed intervertebral foramen. MRI showed that the tumor was a cyst which contained fluid. On thoracotomy a hen's egg sized cyst was found in the posterior mediastinum, the cyst was excised. Pathological diagnosis was a perineurial cyst. This case was clearly differentiated from an intrathoracic meningocele and a neurilemmoma microscopically. This case is the first intrathoracic perineurial cyst in Japan.

Aged↗
PubMed1990

Physicochemical and biological characterization of asialoerythropoietin. Suppressive effects of sialic acid in the expression of biological activity of human erythropoietin in vitro.

Various partially or fully desialylated human erythropoietins were obtained by neuraminidase digestion of the hormone, without non-specific proteolysis and degradation of carbohydrates. Asialoerythropoietin showed a specific activity of 220-IU/mg protein in vivo, although that of the intact erythropoietin was 2.2 x 10(5) IU/mg. A linear relationship was found between the logarithm of the specific activity in vivo and the number of sialic acids. The asialoerythropoietin showed a four-times-higher specific activity in vitro compared with intact erythropoietin using mouse bone marrow cells. It also showed an approximately six-times-higher specific activity in a colony-forming assay for the erythroid colony-forming unit and the erythroid burst-forming unit. Partially or fully de-N-glycosylated erythropoietin derivatives also showed lower in vivo activity but higher in vitro activity than the intact erythropoietin, dependent on the number of sialic acids. To clarify the reason for the enhanced biological activity of asialoerythropoietin in vitro, the binding of intact 125I-erythropoietin or 125I-asialoerythropoietin to cells containing specific receptors for the hormone was analyzed. 125I-asialoerythropoietin bound to spleen cells from anemic mice approximately five times faster than did intact 125I-erythropoietin. The amount of 125I-asialoerythropoietin internalized by target cells, measured in the absence of NaN3, was four times higher than that of intact erythropoietin. These results demonstrate that asialoerythropoietin binds to its receptor faster than the intact form. This may be the main reason for the increased activity of asialoerythropoietin in vitro.

Animals↗
PubMed1990

[Studies on usefulness of postoperative adjuvant chemotherapy with lentinan in patients with gastrointestinal cancer].

The usefulness of Lentinan, as an agent for postoperative adjuvant therapy, was investigated in patients with gastrointestinal cancer. Sixty-one patients were classified into three stages by a degree of advance for cancer (Stage II, III, IV). Furthermore, each group was put into the control group (C group) and the Lentinan group (L group), received 600 mg/day of Tegafur p. o. only or 600 mg/day of Tegafur p. o. and 2 mg/week of Lentinan i. v., respectively. Then total lymphocyte counts and NK cell activities were measured and analysis of lymphocyte subsets by two color flow cytometry was carried out every two months. The results were as follows: 1) Some parameters were preserved in higher levels in the L group especially in the stage IV. 2) In the stage IV, total lymphocyte counts of the L group were preserved higher levels compared to those of the C group. The same tendency was observed in OKT3, OKT4 and OKT8 positive cell counts. 3) In the stage IV, both OKT8+ x Leu15+ cell (suppressor T cell) and OKT8+ x Leu15- cell (killer T cell) counts tended to decrease in the C group. 4) In the stage IV, the NK cell activities of the L group were preserved in higher level compared to those of the C group. Leu7+ x Leu11-, Leu7+ x Leu11+ and Leu11- x Leu11+ cells counts tended to preserve in the L group. From these results, it was suggested that Lentinan had a marked immunopotentiating efficacy in the stage IV among gastrointestinal cancer patients.

Adult↗
PubMed1990

Thrombopoietic activity of human interleukin-6.

Thrombopoietin (TPO), a regulatory factor in platelet production, was purified from the conditioned medium of TNK-01 cells cultured in the presence of human interleukin-1. The N-terminal sequence of purified TPO was determined to be VPPGEDSKDVAAPHRQPLT, identical to that of the N-terminal region of human interleukin-6 (IL-6). Two forms of TPO with molecular masses of 24 and 27 kDa were identified as IL-6 by Western analysis using an anti-IL-6 antibody. Commercial recombinant human IL-6 produced in Escherichia coli, stimulated megakaryocyte colony formation in the presence of mouse interleukin-3 and increased the number of peripheral platelets in mice in a dose-dependent manner. From these results, it is concluded that human IL-6 has thrombopoietic activity.

Amino Acid Sequence↗
PubMed1990

Effect of purified recombinant human erythropoietin on anemia in rats with experimental renal failure induced by five-sixth nephrectomy.

Recombinant human erythropoietin (rHuEPO) was purified from the conditioned media of Chinese hamster ovary cells with a transfected human erythropoietin gene. We investigated the effects of the rHuEPO in rats with renal anemia induced by partial nephrectomy. Five-sixth nephrectomy resulted in renal failure with anemia. Twenty-five days after the operation plasma urea nitrogen was increased about 2.5 times, and the red blood cell count, hematocrit, and hemoglobin concentration fell to 85% of normal. The reticulocyte count and plasma erythropoietin level did not change such as they do in patients with anemia due to chronic renal failure. Both total red blood cell volume and the plasma iron turnover rate were depressed in five-sixth nephrectomized rats compared with normal rats. The five-sixth nephrectomized rats were injected with rHuEPO (60 IU/kg) intravenously every second day for a total of six injections. After three injections of rHuEPO, circulation volume of total red blood cells was increased from 9.9 ml to 14.6 ml, and the plasma iron turnover rate was increased from 1.03 mg/kg/day to 2.12 mg/kg/day, and the reticulocyte count was also increased. After six injections, a marked increase of the red blood cell count, hematocrit, and hemoglobin concentration were observed. Plasma urea nitrogen and the creatinine levels as indications for renal function did not change after rHuEPO administration in both normal and five-sixth nephrectomized rats. In conclusion rHuEPO has a potent erythropoietic action and it is possible to cure the anemia caused by renal failure.

Anemia↗
PubMed1990

Physicochemical and biological comparison of recombinant human erythropoietin with human urinary erythropoietin.

Physicochemical and biological properties of recombinant human erythropoietin (rhEPO) were compared with human urinary erythropoietin (uEPO). uEPO and rhEPO were purified to apparent homogeneity from the urine of patients with aplastic anemia and from the conditioned medium of Chinese hamster ovary (CHO) cells transfected with a cDNA clone for human EPO, respectively. The microheterogeneous nature of both factors, observed on isoelectric focusing, is derived from the difference of the number of terminal sialic acid residues bound to the carbohydrate chains of the EPO molecule. The primary structure of rhEPO, consisting of 165 amino acid residues, was determined, and the C-terminal arginine predicted from the cDNA sequence was confirmed to be missing, as described previously (Recny et al. (1987) J. Biol. Chem. 262, 17156). Three N-glycosylation and one O-glycosylation sites of both factors were determined as Asn24, Asn38, and Asn83 and Ser126, respectively. Two disulfide linkages are located between Cys7 and Cys161, and between Cys29 and Cys33, in both EPOs. Hematogenic potencies of rhEPO and uEPO compared in normal and in partially nephrectomized rats were approximately the same. Both factors also stimulated the colony formation of CFU-E, BFU-E, and CFU-Meg in a dose-dependent manner. From these results, it is concluded that rhEPO produced in CHO cells transfected with cDNA clone for human EPO is indistinguishable from uEPO physicochemically and biologically, and is valuable for further research and for clinical use.

Amino Acid Sequence↗
PubMed1990

Effects of recombinant human erythropoietin on anaemic W/Wv and Sl/Sld mice.

The effects of recombinant human erythropoietin (rHuEPO) on anaemic W/Wv and Sl/Sld mice were investigated. rHuEPO was injected every day for a week in doses up to 86,000 iu/kg. Wv/+ and Sld+ mice, which have genetically a weak anaemia, received 17 or 86 iu/kg of rHuEPO and showed dose-dependent increases in haemoglobin, PCV, RBC and reticulocytes to the same extent as that in normal mice. W/Wv mice also showed increases in the haematological parameters in response to 8600 iu/kg of rHuEPO but the dose was much higher than that for normal mice. A reticulocyte increase in W/Wv mice appeared later than in normal mice and was not sustained for 2 weeks even though the rHuEPO treatment was continued. Sl/Sld mice, however, did not show any significant haematological effect from doses up to 86,000 iu/kg. In both W/Wv and Sl/Sld mice receiving 8600 and 86,000 iu/kg of rHuEPO, respectively, an increase in splenic or bone marrow CFU-E was observed regardless of the defect in their haemopoietic systems. The plasma erythropoietin (EPO) level in W/Wv and Sl/Sld mice was inversely correlated with the haemoglobin, indicating that EPO production was not influenced by the haemopoietic defect and was regulated by the hypoxic properties of the anaemia. These results indicate that a large dose of exogenous rHuEPO is effective for the anaemia in W/Wv mice caused by a stem cell defect but not for the anaemia in Sl/Sld mice caused by a defective microenvironment.

Anemia, Macrocytic↗
PubMed1990

Effects of recombinant human erythropoietin on haemolytic anaemia in mice.

The effects of repeated administration of recombinant human erythropoietin (rHuEPO) were investigated in mice with haemolytic anaemia. Mice with haemolytic anaemia induced by phenylhydrazine (PHZ mice) were examined as an acute model and New Zealand black mice (NZB mice) at 13 months of age were examined as a chronic model. The plasma erythropoietin (EPO) level in PHZ mice was high and showed a strong inverse correlation with the Hb in the anaemia development period. However, it was relatively low in the recovery period from anaemia. On the other hand, the plasma EPO level in NZB mice showed a simple inverse correlation with the Hb. The rHuEPO was injected every day for a week into these mice. While a high plasma EPO level was maintained in PHZ mice, no significant effect was observed by injection with rHuEPO at dose of 600 IU/kg. However, in the recovery period from anaemia, RBC and haemoglobin in PHZ mice were increased by the rHuEPO treatment and recovered more quickly to their normal levels. In NZB mice, RBC and haemoglobin were also increased by treatment with rHuEPO at dose of 600 IU/kg. Anti-RBC autoantibodies and anti-EPO antibodies did not increase, while RBC and plasma EPO levels were increased by the rHuEPO treatment. These results suggest that some types of haemolytic anaemia are not always combined with high endogenous EPO levels and that exogenous rHuEPO may be effective for use in the treatment of haemolytic anaemia.

Acute Disease↗
PubMed1990

Effect of recombinant human erythropoietin on anticancer drug-induced anaemia.

Anaemia was induced in rats with fluorouracil (5-FU) or cisplatin (CDDP) and the mechanisms of anaemia induction were analysed. Furthermore, the therapeutic effects of recombinant human erythropoietin (rHu Epo) on these anticancer drug-induced anaemias were investigated. In 5-FU-induced anaemia, marked serum erythropoietin (Epo) elevation was observed in inverse correlation to blood Hb concentration and Hb concentration rapidly recovered to normal levels. On the other hand, in CDDP-induced anaemia, serum Epo elevation was modest and the lowered Hb concentration persisted longer. Treatment with rHu Epo significantly improved both anticancer drug-induced anaemias but rHu Epo was more effective on CDDP-induced anaemia. These results suggest that rHu Epo might be useful for the therapy of anaemia associated with anticancer chemotherapy.

Anemia↗
PubMed1990

Attenuation of pressor responses to arginine vasopressin in right-sided congestive heart failure.

Although arginine vasopressin (AVP) is elevated in heart failure, inhibition of the vasopressinergic V1-receptor produces minimal changes in blood pressure. To determine whether the V1 vasoconstrictor effect is attenuated in heart failure, we randomly administered three increasing doses of AVP and methoxamine intravenously to 11 dogs with right-sided congestive heart failure (RHF) and 7 sham-operated dogs. Plasma AVP was elevated in RHF (21 +/- 3 pg/ml) compared with sham-operated dogs (3.8 +/- 0.6 pg/ml). While the pressor response to methoxamine was similar in the two groups, AVP caused a smaller increase in mean aortic pressure in RHF dogs than sham-operated dogs. To determine whether the difference in the pressor response to AVP was caused by greater reflex withdrawal of the sympathetic activity in RHF than sham-operated dogs, we also administered AVP after these animals had been pretreated with prazosin and propranolol. Adrenoceptor blockade exaggerated the pressor response to AVP; however, the increase in mean aortic pressure was still smaller in RHF than sham-operated dogs. The diminished pressor response in adrenoceptor-blocked RHF dogs was associated with a smaller increase in total peripheral vascular resistance compared with similarly treated sham dogs. Thus, although the pressor response to AVP was offset by baroreflex activation, the attenuated pressor effect of AVP in heart failure cannot be explained by sympathetic withdrawal alone. AVP probably exerts a smaller direct vasoconstrictor effect when the vasopressinergic system is chronically activated in heart failure.

Animals↗
PubMed1990

[Evaluation of agar media for growth of Campylobacter pylori].

The supporting ability for the growth of Campylobacter pylori was tested on various agar plates. C. pylori grew on media supplemented with blood, serum or egg-yolk, and it showed good growth on Mueller Hinton agar with horse blood, and on brain-heart infusion agar with yeast extract and horse blood. The organism grew moderately on Mueller Hinton agar, but could not grow on the other unsupplemented media. Mueller Hinton medium may be of use as a proper base of blood agar for growth of C. pylori. Egg-yolk may be substituted as a low-priced enrichment material for blood.

Agar↗
PubMed1989

Pathological state of the coagulatory and fibrinolytic system in preeclampsia and the possibility of its treatment with AT III concentrate.

Forty patients with preeclampsia were collected, and 27 of these cases were treated with AT III concentrate (1,000-2,000 units/day) for 7 days. According to an evaluation of objective clinical efficacy by the degree of improvement of GI scores in patients with preeclampsia, the number of effective cases was significantly greater among the treated groups than among the untreated groups (p less than 0.05). The rate of efficacy of the treated groups was 40%, compared with 0% in the untreated groups. In severe preeclampsia, a decrease in AT III activity was noted in 56.7%, a decrease in platelet count in 62.1%, and an increase in plasma FDP in 46.2%. A significant correlation was found between the GI score and the AT III activity. The anticoagulation therapy using AT III may normalize the chronic coagulation accelerated state in preeclampsia, and a good influence on the fetus may be expected.

Adult↗
PubMed1989

[Myocardial perfusion assessed by dynamic computed tomography, with respect to viable muscle in the infarcted region].

To clarify the significance of regional myocardial perfusion, 31 patients of old myocardial infarction including 11 cases undergoing PTCA with a left anterior descending artery lesion were studied using dynamic transmission computed tomography with excellent time resolution. Serial one-second dynamic scans with an electrocardiographic triggering system were performed at the middle level of the left ventricle using a bolus injection of contrast medium via the inferior vena cava. The F/V (F = flow, V = volume) ratio, a parameter of perfusion per unit of myocardium, was calculated from gamma-variate fitted time density curves obtained in the myocardium and in the left ventricular cavity. The F/V ratio was significantly lower in patients not only with severe but also mild and no coronary artery stenosis (post PTCA: 185 +/- 54, 50-75% stenosis: 193 +/- 47, 90% stenosis: 181 +/- 51, 99% stenosis: 140 +/- 34, 100% stenosis: 142 +/- 27 ml/min/100 g, control value: 243 +/- 51 ml/min/100 g, post PTCA, 50-75% stenosis, 90% stenosis vs control p less than 0.05, 99%, 100% stenosis vs control p less than 0.005). The functional images depicting myocardial perfusion frequently revealed abnormal perfusion findings in patients not only with severe but also mild and no coronary stenosis. In the patients with mild or insignificant coronary stenosis, the F/V ratio was dependent on the severity of left ventricular wall motion abnormalities (hypokinesis: 192 +/- 51, akinesis or dyskinesis: 141 +/- 32 ml/min/100 g; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗