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Biomedical subjects

N Koyama

Publications and source records attributed to N Koyama.

At least 163 records · Page 9Linked to original sources
PubMed1991

Association of neonatal thrombocytopenia and maternal anti-HLA antibodies.

In order to evaluate the influence of maternal anti-HLA antibody on neonatal thrombocytopenia, clinical features and maternal anti-HLA antibody of three groups of infants (19 thrombocytopenic and low birth weight, 27 nonthrombocytopenic and low birth weight, and 80 healthy full-term) were investigated. The incidence of positive maternal anti-HLA antibodies in the three groups was 73.7%, 29.6% and 27.5%, respectively. Thrombocytopenia in small-for-gestational-age (SGA) infants was closely related to the presence of maternal anti-HLA antibodies. Among 20 SGA infants (11 thrombocytopenic, 9 non-thrombocytopenic), anti-HLA antibody was detected in 10 mothers (90.9%) of thrombocytopenic SGA infants, while it was positive in only one mother (11.1%) of nonthrombocytopenic SGA infants. Investigation of the SGA infants revealed that in those whose mothers were sensitized to HLA antigen, not only the platelet count but also the leukocyte and lymphocyte counts in the first week of life were significantly lower than in infants whose mothers were not sensitized. The results suggest that the presence of maternal anti-HLA antibody is a cause of neonatal thrombocytopenia especially in SGA infants.

Antibodies↗
PubMed1991

Surfactant apoprotein A (SP-A) in tracheal aspirates of newborn infants with RDS.

Human pulmonary surfactant contains four groups of apoproteins, SP-A, B, C and D. We determined the concentration of SP-A in the tracheal aspirate of newborn infants by a two-site simultaneous immunoassay with monoclonal antibodies, and used this assay to assess changes in surfactant in various clinical situations. SP-A concentrations were standardized per milligram of albumin in the aspirate. The ratio of SP-A/albumin (micrograms/mg) in tracheal aspirates of 18 preterm infants with respiratory distress syndrome (RDS), in which samples were obtained within 12 hours of birth, was significantly lower (0.2 +/- 0.1 microgram/mg, mean +/- S.D.) compared to a group of 20 non-RDS preterm infants of similar gestational age (15.8 +/- 7.4 micrograms/mg) (p less than 0.05). None of the RDS infants had a SP-A/albumin ratio above 1 microgram/mg within 12 hours of birth, but the ratio exceeded 5 micrograms/mg in all samples from non-RDS infants. The SP-A/albumin ratio significantly increased, however, at 48 to 72 hours after birth in infants with RDS (15.7 +/- 9.5 micrograms/mg). During the recovery phase of RDS, no difference was evident in the SP-A/albumin ratio in babies treated with artificial surfactant compared to those not treated.

Albumins↗
PubMed1991

[Left ventricular wall damage as an indicator for valve replacement in patients with volume overload: a radionuclide study].

Using Tl-201 myocardial single photon emission computed tomography (SPECT), we tried to utilize the Tl-defects to determine the timing for aortic or mitral valve replacement in cases with chronic aortic (AR) or mitral regurgitation (MR), or both. Examinations including echocardiography and angiography were performed to evaluate left ventricular dilatation. Subjects consisted of 80 patients, including 22 with AR, 26 with MR, 17 with AR+MR, and 15 post-operative cases. The Tl-scores (sum of the grade of Tl-defects) correlated well with T wave abnormalities (V5) and NYHA functional class. The scores also correlated with left ventricular end-diastolic dimension (LVDd) and LV ejection fraction (LVEF), indicating that the LV wall defect progressed as the LV dimension increased with the increase in the volume load. Exercise Tl-201 myocardial SPECT revealed redistribution at an early stage of valvular regurgitation, indicating the development of LV wall damage in cases of LV enlargement due to regurgitation. Valve replacement caused a decrease in LVDd, with mild improvement in the Tl-score. We concluded that, in addition to the T wave changes and the echocardiographic measurements, Tl-201 myocardial SPECT should be included in the criteria for valve replacement.

Aortic Valve Insufficiency↗
PubMed1991

[Resection of metastatic pulmonary lesion of osteosarcoma extended into the left atrium and ventricle via the pulmonary vein].

A 35-year-old woman had underwent an amputation of the right hemimandibula for an osteosarcoma. Twenty months after the operation, she was admitted to our hospital with complaints of syncope. On chest computed tomography and echocardiography, an atrial tumor was disclosed, which extended from the lesion of the left pulmonary lower lobe. This tumor intravascularly developed through the left inferior pulmonary vein. The intracardiac tumor was resected through left atriotomy under cardiopulmonary bypass, and immediately after weaning of bypass left lower lobe was resected. On pathological study the tumor was diagnosed as metastasis of osteosarcoma. Despite postoperative chemotherapy including CDDP, she died of metastasis in pulmonary, adrenal gland and liver 12 months after the second operation.

Adult↗
PubMed1990

Bifunctional effects of transforming growth factor-beta on migration of cultured rat aortic smooth muscle cells.

Migration of smooth muscle cells (SMC) in the arterial wall is important in the pathogenesis of atherosclerosis and is presumably regulated in both normal and atherosclerotic tissues. In this study, the effect of transforming growth factor-beta (TGF-beta) on the migration of rat aortic SMC was examined. TGF-beta alone enhanced the migration of SMC at concentrations of 10 to 50 pg/ml and its maximal effect was similar to that of platelet-derived growth factor (PDGF). Checker board analysis showed that TGF-beta had a chemotactic, but not a chemokinetic effect. PDGF also enhanced the migration in a dose-dependent manner and TGF-beta inhibited the PDGF-induced migration dose-dependently at 1.0 pg/ml to 1.0 ng/ml. These data suggest that TGF-beta is a bifunctional regulator of the migration of aortic SMC.

Animals↗
PubMed1990

[Surgical repair for pulmonary artery sling on a 46-day-old infant].

Surgical repair on a 46-day-old girl with pulmonary artery sling is reported. She was suffered from dypnea and admitted to a hospital on 12 days after her birth. On chest roentgenogram atelectasis of right lung was found. She had been on respirator since 21 days after her birth. On bronchogram and pulmonary arteriogram, the trachea and right bronchus were compressed and shifted with the anomalous origin of left pulmonary artery which originated from the right pulmonary artery and passed between the trachea and esophagus. These results confirmed the diagnosis of pulmonary artery sling. Hence, she was referred to our hospital for surgical treatment. She underwent surgical repair on 46-day-old. In operation, we chose a mid-sternal splitting incision, and excised 5 mm of ductus arteriosus. Under extracorporeal circulation, the left pulmonary artery was amptated from the right pulmonary artery and pulled back to left side between the trachea and the esophagus. The left pulmonary artery was anastomosed to the main pulmonary artery at the anterior to the left bronchus. She weaned from respirator, and was extubated on the 3rd day after procedure. She recovered uneventfully in post-operative course. On the 24th day after operation she discharged from hospital. On pulmonary perfusion scanning and pulmonary arteriography performed one year after operation, the left pulmonary artery was patient with slightly decreased perfusion in the left lung. Surgical repair for pulmonary artery sling was recognized as high mortality because of frequently associated tracheobronchial anomalies. In the Japanese literature, only 4 patients survived surgically and lived in late stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

Characterization of the membrane-bound ATPase from a facultatively anaerobic alkalophile.

We have studied the properties of membrane-bound ATPase of a facultatively anaerobic alkalophile. The enzyme could not be solubilized without detergent, suggesting an integral membrane protein. The activity was accelerated by NH4+ and acetate anion, and inhibited by NH3-. The enzyme required Mg2+ or Mn2+ as a divalent cation for the maximal activity. In addition to ATP, the enzyme utilized other triphosphates of nucleosides as a substrate, but not di- nor monophosphates. The enzyme was suggested to crossreact with an antibody against the alpha-subunit of Na+/K+-ATPase from dog kidney.

Adenosine Triphosphatases↗
PubMed1989

Effects of smooth muscle cell derived growth factor (SDGF) in combination with other growth factors on smooth muscle cells.

Recently intimal thickening was shown to be due to stimulation of proliferation of arterial smooth muscle cells (SMC) by autocrine secretion of growth factor(s). We have reported that cultured rabbit aortic SMC secrete a growth factor (SDGF) distinct from other known growth factors. This paper reports on studies on the biological characteristics of SDGF. Putative "competence" and "progression" growth factors synergistically stimulated DNA synthesis of cultured rabbit aortic SMC. Conditioned medium (CM) from SMC containing SDGF stimulated DNA synthesis in SMC synergistically with either the competence factors or the progression factors. This synergistic effect was also observed in the presence of optimal concentrations of both competence and progression factors. The continuous presence of CM was essential for its stimulation of DNA synthesis whereas the presence of PDGF for only the first 4 h of culture was sufficient to induce maximum stimulation of DNA synthesis. These results suggest that SDGF is a new growth factor distinct from either competence or progression factors and that it stimulates a different pathway in SMC from those stimulated by other known growth factors.

Animals↗
PubMed1989

Electrophysiological changes in the fasciculus gracilis of the cat following chronic clioquinol administration.

Clioquinol was administered to cats for more than 200 days, in order to investigate the neural mechanisms underlying the sensory disturbances of subacute myelo-opticoneuropathy (SMON). Electrophysiological examination, carried out under urethane-chloralose anesthesia, revealed that there were 3 major abnormalities in the surface potentials of the nucleus gracilis evoked by sural nerve stimulation, i.e., a reduction in the peak-to-peak amplitude, prolongation of the N wave, and a reduction in P wave amplitude. The reduction in P-wave amplitude suggested suppression of presynaptic inhibition. This was confirmed by excitability tests of the presynaptic terminals of sural nerve fibers within the nucleus gracilis. Recordings of orthodromic volleys in the fasciculus gracilis, elicited by sural nerve stimulation, showed an increase in temporal dispersion. Increased temporal dispersion was also evident from recordings of antidromic volleys in the sural nerve. Peripheral axons of primary sensory neurons in the sural nerve and their terminals within the spinal cord showed no significant functional abnormalities in the chronic clioquinol cat. It is suggested that primary axons in the fasciculus gracilis near the nucleus gracilis are affected by chronic clioquinol administration.

Action Potentials↗
PubMed1989

Tryptic digestion of NADH dehydrogenase from alkalophilic Bacillus.

The alkalophile NADH dehydrogenase (NADH: 2,6-dichlorophenolindophenol oxidoreductase) [EC 1.6.99.3] consists of two identical subunits of 65 kDa, and each subunit contains the catalytic and liposome-binding regions. On treatment with trypsin, the polypeptide exhibiting the liposome-binding property in one of the subunits was digested to form an enzymatically active hetero-dimer (40 and 65 kDa), and then the polypeptide in the other subunit was digested to form an active homo-dimer (40 and 40 kDa). The hetero-dimer bound to liposomes, but the homo-dimer did not. Kinetic analysis showed that removal of one or two of the polypeptides in the enzyme slightly affects its kinetic parameters. For all the enzyme species, NAD inhibited competitively with respect to NADH and non-competitively with respect to 2,6-dichlorophenolindophenol. The partially determined amino acid sequence of this alkalophile enzyme suggested that (i) a long random-coiled peptide (58 amino acid residues) or a portion of the peptide is located between the polypeptides with liposome-binding and catalytic properties, (ii) the polypeptide exhibiting liposome-binding property is in the amino terminal region of the enzyme, (iii) the amino acid sequences around the subtilisin and trypsin cleavage sites of the peptide are hydrophilic and on the surface of the protein molecule and therefore are susceptible to digestion, and (iv) the FAD-binding site is located near the amino terminal region of the catalytic region.

Amino Acid Sequence↗
PubMed1989

Rectal absorption of E-2078 (dynorphin analogue peptide) in rats.

The plasma levels in rats of a dynorphin analogue peptide (E-2078) after rectal administration have been studied. The bioavailabilities of E-2078 after rectal administration, subcutaneous injection, intramuscular injection, and oral administration were 21.6, 67.8, 67.1, 0.7%, respectively. The effect of dose, pH, osmolarity and viscosity on the rectal absorption of E-2078 were studied. A sigmoid relationship between the dose and the AUC was observed on rectal administration, while there was a linear relationship on intramuscular administration. The AUC was increased in acidic solution and highly viscous solution. The osmolarity did not affect the absorption of E-2078. In microscopic studies, E-2078 caused little or no damage to the rectal mucosa in rats.

Administration, Oral↗
PubMed1989

Molecular cloning of the structural gene for alkaline elastase YaB, a new subtilisin produced by an alkalophilic Bacillus strain.

Alkaline elastase YaB is an extracellular serine protease of the alkalophilic Bacillus strain YaB. We cloned the structural gene, ale, and determined the nucleotide sequence. The mature enzyme (268 amino acids) was preceded by a putative signal sequence and a prosequence (27 and 83 amino acids, respectively). The mature enzyme was 55% homologous to subtilisin BPN'. Almost all the positively charged residues are predicted to be on the surface of the molecule, which would facilitate binding to elastin. The P1 substrate site-related sequences differed between alkaline elastase YaB and subtilisin BPN'.

Amino Acid Sequence↗
PubMed1989

[The evaluation of left ventricular eccentric hypertrophy by 201Tl-myocardial scintigraphy].

In order to elucidate the mechanism of left ventricular eccentric hypertrophy in conditions of volume overload, Tl-201 myocardial scintigraphy was performed patients with aortic valve regurgitation and mitral valve regurgitation. There was a good relationship between the severity of Tl-defects, as determined by Tl-201 myocardial scintigraphy, and the changes in the T wave on the ECG on the one hand and the NYHA functional classification of heart diseases. In 17 of 18 patients where LVDd increased with increasing severity of Tl-defects and the defects were moderate to severe, LVDd was 65 mm or larger. There was a significant negative correlation between the washout rate for the whole circumference of the left ventricle, as determined by exercise Tl-201 SPECT, and LVDd (r = -0.603, p less than 0.01). The phenomenon of redistribution as determined by exercise Tl-201 myocardial scintigraphy was observed relatively early. Our results suggest that mechanical volume overload and ischemic changes are involved in left ventricular wall damage in left ventricular eccentric hypertrophy. For patients with moderate to severe Tl-defects valve replacement is indicated, no matter whether they may have heart failure or arrhythmia.

Adult↗
PubMed1989

[Clinical assessment of myocardial protection with blood-GIK solution].

Since Jan, 1984, three different types of myocardial protection have been tried in coronary bypass surgery. These are GIK (1984. 1-1984. 12), Young+GIK (1985. 1-1986. 8), and blood GIK (1986. 9-until present). In this study we tried to demonstrate the advantage of myocardial protection induced with blood GIK solution in comparison with that with GIK alone or Young + GIK. (Materials and methods) Eighty-three patients undergone coronary bypass surgery in that period, were evaluated and divided into three groups: Group I had myocardial protection with GIK alone in 24 patients, group II had myocardial protection with Young + GIK in 28 patients, and group III had myocardial protection with Young + blood GIK in 31 patients. Among these groups, the changes of serum enzymes and hemodynamics in postoperative period were compared. (Results) In the hemodynamic changes, cardiac index at 24 hours after operation in group III, was higher than that in the other two groups (p < 0.05). The peak value of MB-CPK in all groups appeared 12 hours after operation, however, 21.9 +/- 19.72 IU/ml in group III was significantly lower than 33.4 +/- 25.5 in group I, or 36.9 +/- 26.8 in group II (p < 0.01). The results demonstrates that the myocardial protection induced with blood GIK are superior to these with the other two method.

Cardioplegic Solutions↗
PubMed1988

Dual somatosensory representation of the periodontium in nucleus ventralis posteromedialis of the cat thalamus.

The distribution of periodontal units within the nucleus ventralis posteromedialis (VPM) was studied in urethane-chloralose-anesthetized cats. Recordings were made from a total of 63 periodontal units. Of these, 55 received contralateral input, the rest receiving ipsilateral input. The periodontal units receiving contralateral inputs were located in the medial part of the VPM proper, whereas those receiving ipsilateral inputs were found in the lateral subdivision of the nucleus ventralis posteromedialis parvocellularis (VPMpcl).

Action Potentials↗