Biomedical subjects

S Kawamura

Publications and source records attributed to S Kawamura.

At least 163 records · Page 9Linked to original sources

PubMed1997

[Hematological characteristics of hypoplastic MDS patients with chromosomal abnormalities, who had been followed for aplastic anemia with normal karyotypes].

During 1990 to 1993, five patients who had been treated in our hospital for aplastic anemia (AA) with a normal karyotype, were found to have hypoplastic myelodysplastic syndromes (hMDS); three patients with RA, one RAEB, and one RAEB-T, and all of them have chromosomal abnormalities. The mean age of the hMDS patients (4 men, 1 woman) was 51.0 years (range 31-61). We retrospectively studied the hematological features of the 5 cases in the early stage without chromosomal abnormalities. They showed, 1) appearance of erythroblasts (3/5), 2) more reticulocyte counts than typical AA (mean 7.8 x 10(4)/microliter), 3) macrocytic anemia (mean MCV 106fl) in peripheral blood, 4) relative erythroid hyperplasia (M/E ratio 0.2-1.5), and 5) low lymphocyte counts (mean percentage of lymphocytes 32, 8%) in bone marrow. Considering about the differences or transformation between AA and hMDS, it is interesting that all five patients have initially had a normal karyotype and subsequently developed chromosomal abnormalities.

Adult↗

PubMed1996

Molecular characterization of the pigeon P-opsin gene.

The chicken gene encoding pineal gland-specific opsin (P-opsin) has been previously characterized. We report here the orthologous pigeon (Columba livia) P-opsin gene. The deduced pigeon P-opsin lacks a potential N-glycosylation site in the N-terminus, but has multiple phosphorylation sites in the C-terminus, which are opposite from the characteristics of the chicken P-opsin.

Amino Acid Sequence↗

PubMed1996

Photoreceptor protein s26, a cone homologue of S-modulin in frog retina.

A frog retinal protein named s26 is a 26-kDa protein found during purification of S-modulin in frog retina (Kawamura, S. (1992) Photochem. Photobiol. 56, 1173-1180). To identify its role in frog retina, first s26 was purified to nearly homogeneity with three chromatographical steps. Based on the partial amino acid sequences of the proteolysed fragments of s26, we isolated cDNAs that encode s26. The analysis of its amino acid sequence revealed that s26 is an S-modulin-like protein, while it shows higher homology to visinin. Visinin is a Ca2+-binding protein reported to be present in chicken cones, but its localization in the retina had been a subject in dispute. The present study showed that s26 is present in cone photoreceptors. The study also showed that s26 inhibits phosphorylation of rhodopsin after a light flash at high Ca2+ concentrations as S-modulin does. From these results, we concluded that s26 is a cone homologue of S-modulin. The result is consistent with the idea that each type of photoreceptors expresses each cell-type specific version of phototransduction proteins.

Amino Acid Sequence↗

PubMed1996

Glycine-15 in the bend between two alpha-helices can explain the thermostability of DNA binding protein HU from Bacillus stearothermophilus.

On the basis of sequence comparison of thermophilic and mesophilic DNA binding protein HUs, Bacillus stearothermophilus DNA binding protein HU (BstHU) seems to gain thermostability with a change in amino acid residues present on the molecular surface. To evaluate the contribution of exchange of each amino acid to the thermostability of BstHU, we constructed three mutants, BstHU-T13A (Thr13 to Ala), BstHU-G15E (Gly15 to Glu), and BstHU-T33L (Thr33 to Leu), in which the amino acids in BstHU were changed to the corresponding ones in Bacillus subtilis DNA binding protein HU (BsuHU). Stability of the mutant proteins was determined from thermal-denaturation curves. Replacement of Gly15 located in the turn region between alpha 1 and alpha 2 helices (HTH motif), with Glu (BstHU-G15E), resulted in a decrease in thermostability, and the Tm value was 54.0 degrees C compared to the Tm value of 63.9 degrees C for BstHU. The mutants, BstHU-T13A and BstHU-T33L, were, by contrast, slightly more stable (Tm values of 67.0 and 65.6 degrees C for BstHU-T13A and BstHU-T33L, respectively) than the wild type. We then generated the BsuHU mutant protein BsuHU-E15G, where Glu15 in BsuHU was in turn replaced by Gly, and we analyzed the thermostability. This substitution clearly enhanced the melting temperature by 11.8 degrees C (Tm value: 60.4 degrees C for BsuHU-E15G) compared to the value for BsuHU (Tm: 48.6 degrees C). Thus, Gly15 in the HTH motif of BstHU has an important role in the thermostability of BstHU. Characterization of the structure of the BstHU-G15E by 1H-NMR analysis showed that solvent accessibility of amide proton of Ala21 in the mutant was significantly increased compared with that of wild type, which means that the structure of the HTH motif in the N-terminal region in the mutant was changed to a more open conformation, thereby avoiding the interaction of Ala21 with either Ser17 by hydrogen bond or Ala11 by hydrophobic interaction.

Bacterial Proteins↗

PubMed1996

Histological changes in rat embryonic blood cells as a possible mechanism for ventricular septal defects produced by an N-phenylimide herbicide.

An N-phenylimide herbicide, S-53482, inhibits protoporphyrinogen oxidase, an enzyme common to chlorophyll and heme biosynthesis, and produces embryolethality, teratogenicity [mainly ventricular septal defects (VSD) and wavy ribs], and growth retardation in rats. In order to elucidate the mechanism of the developmental toxicity, in particular VSD, effects of the herbicide on rat embryonic blood cells were investigated histologically at the light and electron microscopic levels at 6, 12, 24, 36, and 48 h after oral administration of the chemical to pregnant rats on day 12 of gestation, the most sensitive day for toxicity. Electron and light microscopy demonstrated mitochondrial lesions, including abnormal iron deposits that were probably due to inhibition of heme biosynthesis, in erythroblasts derived from the yolk sac. Subsequently, degeneration of these erythroblasts occurred followed by erythrophagocytosis. Histologically hearts from exposed embryos had a thin ventricular wall, which may reflect a compensatory reaction to a loss of embryonic blood cells. Thus, the herbicide may induce VSD due to hematological dysfunction caused by the inhibition of heme biosynthesis rather than by direct injurious effects on the heart.

Animals↗

PubMed1996

Effects of feeding on conditioned avoidance responses in rats.

Possible effects of feeding on learning were studied by comparing learned avoidance rates among three groups of Wistar rats that were given a diet at 1 h (1-h pretest group) and 5 h (5-h pretest group) before and immediately after (post-test group) the conditioned avoidance test. Learned avoidance rates during eight test sessions were higher in the order of the 1-h pretest, post-test, and 5-h pretest groups. This suggests that both pre- and post-test (training) feeding facilitates acquisition of conditioned avoidance learning presumably based on neurohumoral processes influenced by available glucose concentrations.

Animals↗

PubMed1996

Species difference in protoporphyrin IX accumulation produced by an N-phenylimide herbicide in embryos between rats and rabbits.

There was a remarkable species difference in developmental toxicity exhibited by S-53482, an N-phenylimide photobleaching herbicide, between rats and rabbits. S-53482 showed embryolethality, teratogenicity, and growth retardation in rats. In contrast, no developmental toxicity was shown in rabbits. The herbicidal activity of S-53482 is due to the photodynamic action of accumulated protoporphyrin IX (PPIX) as a result of inhibition of protoporphyrinogen oxidase (PPO), which is one of the key enzymes in porphyrin biosynthesis common to both plants and animals as part of chlorophyll and heme synthesis. Some plant PPO inhibitors were reported to inhibit mammalian PPO. Therefore, in a search for a possible link between developmental toxicity and enzyme inhibition, PPIX accumulations presumably resulting from PPO inhibition in rat and rabbit embryos were investigated. The results demonstrated that PPIX concentration was increased in rat embryos by 2 orders of magnitude when compared to that of nontreated embryos. On the other hand, no PPIX was accumulated in rabbit embryos even by treatment with a high dose level of S-53482. It was concluded that the species difference in PPIX accumulation corresponded very well to that of the developmental toxicity exhibited by S-53482.

Animals↗

PubMed1996

Therapeutic effect of secretin in patients with jaundice; double-blind placebo-controlled multicentric trial.

Secretin, a gastrointestinal hormone, has been shown to have a potent choleretic effect. Having already obtained some beneficial effects with secretin in patients with intrahepatic cholestasis, we sought to confirm its effects in a double-blind placebo-controlled study in patients with mild jaundice after acute or during chronic hepatitis, where total bilirubin level was in excess of 4.0 mg/dl for 3 days or more. Patients with primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), and familiar hyperbilirubinemia were excluded from the study. Ninety-three patients were included in this analysis, but the final evaluation covered 69 of them. No statistically significant differences were found in the reduction of serum bilirubin levels between secretin and placebo groups. As a number of patients with liver cirrhosis had been included, the subjects were subdivided into one group with cholestasis in hepatitis and one with liver cirrhosis. In the subgroup of cirrhotic patients who received secretin, serum levels of AST were significantly increased compared with the placebo group. However, since the choleretic effect of secretin is unique, further studies seem to be warranted.

Adolescent↗

PubMed1996

Phylogenetic relationships among short wavelength-sensitive opsins of American chameleon (Anolis carolinensis) and other vertebrates.

The vertebrate opsins have been classified into four major phylogenetic groups. One of them, a short wavelength-sensitive (SWS) opsin group, is further divided into two subgroups, SWS-I and SWS-II, having the wavelengths of maximal absorption of about 420 and 450 nm, respectively. Here we report the DNA sequences of the SWS-I and SWS-II genes from the lizard Anolis carolinensis. The shorter wavelengths of absorption by the two SWS subgroup opsins seem to be achieved by different sets of amino acid replacements in the transmembrane regions.

Amino Acid Sequence↗

PubMed1996

Purification of bovine beta 2-microglobulin from colostrum and its complete amino acid sequence.

Bovine beta 2-microglobulin (beta 2-m) was purified from colostrum milk in two chromatographic steps: anion-exchange chromatography, and gel filtration. The amino acid sequence was determined to confirm that the purified protein was beta 2-m. A molecular weight of 11.8 kDa beta 2-m was estimated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Bovine beta 2-m consists of 98 amino acid residues and contains one disulfide linkage connecting residues 25 and 79. The amino acid sequence determined by this study is different from a previously published sequence at three sites, but agrees with the amino acid sequence from cDNA. Thus, we can conclude that the amino acid sequence determined in this study is correct.

Amino Acid Sequence↗

PubMed1996

Direct projections from the pedunculopontine and laterodorsal tegmental nuclei to area 17 of the visual cortex in the cat.

Direct projections from the pedunculopontine tegmental nucleus (PPT) and the laterodorsal tegmental nucleus (LDT) in the brainstem to area 17 of the visual cortex were investigated in the cat by the tract-tracing method with WGA-HRP. Neurochemical nature of neurons which were labeled retrogradely with WGA-HRP injected into area 17 was also examined immunohistochemically with antibodies against choline acetyltransferase (ChAT), tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH), and serotonin (5-HT). After injections of WGA-HRP into area 17, neurons in the caudal half of the PPT and the LDT were retrogradely labeled bilaterally with marked ipsilateral predominance. In the LDT, about 20% of the labeled neurons showed ChAT immunoreactivity (ChAT+); the vast majority (about 80%) of the labeled cells showed TH(+) and DBH(+). In the PPT, all retrogradely labeled cells exhibited TH(+) and DBH(+), but not ChAT(+). No retrogradely labeled cells with WGA-HRP showed 5-HT(+) in the PPT or LDT. The results indicate that the caudal part of the PPT and LDT sends projection fibers to area 17, and that PPT-neurons projecting to area 17 are noradrenergic, whereas LDT-neurons projecting to area 17 are cholinergic (20%) and noradrenergic (80%).

Adrenergic Fibers↗

PubMed1996

[Two cases of pulmonary dirofilariasis in Nagasaki Prefecture].

We reported two cases of pulmonary dirofilariasis in Nagasaki Prefecture. Each case was admitted to our hospitals for evaluation of an abnormal shadow on chest X-ray film taken for examination. We strongly suspected lung cancer before operation. It was resected in order to confirm the pathological diagnosis. There was a Dirofilaria immitis in the vessels surrounded by the necrotic tissues. The case of pulmonary dirofilariasis tends to increase in Japan, but the positive rate of dogs with Dirofilaria immitis tends to decrease, because of decreasing breeding places of mosquitoes by the spread of the public sewage system in Nagasaki City.

Adult↗

PubMed1996

Enolase antigen, mannan antigen, Cand-Tec antigen, and beta-glucan in patients with candidemia.

We compared the specificities and sensitivities of four tests used for the serodiagnosis of candidemia in 39 patients with candidemia, including 10 patients with superficial Candida colonization, 10 patients with deep mycosis, and 20 healthy subjects. The results obtained by the dot immunoblotting assay for detecting the enolase antigen (48 kDa) were compared with those of assays for detecting mannan antigen, heat-labile antigen (a threshold titer of four times), and beta-glucan (> or = 60 pg/ml). Enolase antigen was detected in 28 (71.8%) patients with candidemia, while 30 (76.9%), 10 (25.6%), and 27 (84.4%) patients were positive for the heat-labile antigen by the Cand-Tec assay, the mannan antigen by the Pastorex Candida assay, and beta-glucan by the limulus test, respectively. Ten patients with superficial Candida colonization, 5 patients with invasive pulmonary aspergillosis, 5 patients with cryptococcosis, and 20 healthy subjects were negative for both enolase antigen and mannan antigen. Two patients with superficial Candida colonization, one patient with invasive pulmonary aspergillosis, and two patients with cryptococcosis were positive by the Cand-Tec assay. The beta-glucan concentration was more than 60 pg/ml in all patients with invasive pulmonary aspergillosis; however, it was less than 10 pg/ml in all patients with cryptococcosis. The specificity of enolase antigen in the serodiagnosis of candidemia was 100%, but the sensitivity was 71.8%. The specificity and sensitivity of Cand-Tec, the assay for mannan antigen, and the assay for beta-glucan were 76.9 and 87.5%, 25.6 and 100%, and 84.4 and 87.5%, respectively. Our results demonstrated that antigen detection tests are useful for the diagnosis of candidemia; however, none is satisfactory for the serodiagnosis of candidemia. We suggest that a combination of two assays may increase the accuracy of diagnosis of candidiasis.

Adult↗

PubMed1996

[Pressure changes in the renal pelvis of the dogs in response to a sudden rise in intravesical pressure, examined in the presence of resico ureteral reflux with artificial ureter and/or pelvis].

This study is to determine which part or the upper urinary tract, ureter or pelvis causes more significant delay in the pressure wave-front propagation from the bladder to the pelvis when a reverse flow of the urine occurs. A sudden rise in the intravesical pressure of the dog was produced by stimulating the vesical branches of pelvic nerve with a train of electrical impulses with 10 Hz for 60 sec. In order to eliminate the physiological mechanism that presents a reverse flow of the urine at the uretero-vesical junction, a 3 cm vinyl tube was inserted into the ureteral orifice in all experiments except the cases with ureteral substitution (group II and III). Changes in intrapelvic pressure were measured from 7 dogs without substitution of either ureter or pelvis, and used as the control responses for comparison with those recorded from the dogs with artificial ureter and/or pelvis. Artificial ureter was made by a vinyl tube of 25 cm, whereas artificial pelvis was made by a 3 ml plastic chamber. Twenty-eight dogs were divide into 3 groups. Group I consisted of 7 dogs whose pelvises were replaced by artificial ones. Group II included 8 dogs whose ureters were substituted by artificial ones, and group III consisted of 6 dogs whose both ureter and pelvis were replaced by artificial ones. Results obtained were as follows; (1) There was no significant difference between the maximum intravesical pressure and the maximum intrapelvic pressure recorded from every dog in all groups. (2) The onset time of intrapelvic response recorded from the control dog showed a delay from that of intravesical response by 2.05 +/- 1.03 sec. (3) The onset time of intrapelvic response recorded from group I, II and III were 0.51 +/- 0.94 sec., 1.95 +/- 1.10 sec., 0.10 +/- 0.25 sec., respectively. (4) Statistically significant difference in the delay of response was observed only between the responses recorded from the control or group II and the responses recorded from group I or III. The above results suggested that the major site causing a significant delay in the pressure wave-front propagation from the bladder to the pelvis is the pelvic area including caryx, but not the ureteral region, when a reverse flow of the urine occurs.

Animals↗

PubMed1996

Protective effect of nilvadipine on focal cerebral ischemia in spontaneously hypertensive rats.

The protective effect of nilvadipine, a Ca2+ antagonist, on cerebral ischemia was investigated in spontaneously hypertensive rats. The 12-week-old animals were treated for 7 days with either nilvadipine or vehicle using osmotic pumps implanted subcutaneously. Group 1 animals (n = 10) received the vehicle, and Group 2 (n = 10) and 3 animals (n = 10) received 1 and 3 mg/kg/day nilvadipine, respectively. The left middle cerebral artery was occluded under halothane anesthesia on the 6th day of treatment, and neuropathological outcomes were quantified 24 hours later. The systolic blood pressure measured before occlusion decreased to 137 +/- 9 mmHg (Group 2) and 130 +/- 9 mmHg (Group 3), compared to 189 +/- 12 mmHg for Group 1 (p < 0.05). The percentage infarct volumes in Groups 1-3 were 39 +/- 3%, 37 +/- 2%, and 34 +/- 3%, respectively (p < 0.05, Groups 1 vs. 3). Therefore, nilvadipine decreased the infarct size dose-dependently. Nilvadipine has a protective effect against cerebral ischemia in rats with chronic hypertension. Neuropathological findings suggest that nilvadipine may act at the ischemic penumbra. Nilvadipine may have the additional benefit of reducing the consequences of a possible later stroke in patients with hypertension (one of the risk factors for stroke).

Animals↗

PubMed1996

Vascular response to hyperoxemia in rat brain surface microvessels.

The effects of hyperoxemia on pial vessel diameters were studied in rats using a cranial window technique. The brain surface was superfused with mock cerebrospinal fluid at 5 ml/hr, and the intracranial pressure was maintained at 5 mmHg. Animals were artificially ventilated, and the arterial carbon dioxide tension was constantly controlled in each animal. Arterioles (14-90 microns diameter during air inhalation) constricted significantly according to the arterial oxygen tension (PaO2) increase: 94 +/- 7% (30% O2), 91 +/- 8% (60% O2), and 88 +/- 8% (100% O2). The percentage diameter change per mmHg PaO2 increase was 0.1% under normoxemia, but became less under hyperoxemia (0.025% and 0.01% per mmHg during 30%-to-60% and 60%-to-100% O2 inhalations, respectively). The diameter change between 60% and 100% O2 inhalations was not significant. There was no significant relationship between the vascular response and the control diameter. Some small arterioles (< or = 50 microns diameter) underwent marked constriction (-20% to -35%), but there were no large vessels (> 50 microns diameter) showed a constriction greater than -20%. Venules (17-114 microns diameter) did not have a significant response to hyperoxemia. The vasoconstriction of pial arterioles was proportional to arterial O2, but the relationship was not linear.

Animals↗

PubMed1996

An explanation for inconsistency between psychophysical functions derived from different scaling methods on a prothetic continuum.

In this note is proposed an hypothetical explanation for the question of why, on a prothetic continuum, a psychophysical function obtained by direct scaling is inconsistent with that obtained by indirect scaling. We explain by making the assumption that there are two stages of sensory processes which transform a given stimulus value to a perceived value serially by logarithmic and exponential functions. It is illustrated that, on a prothetic continuum, a logarithmic function should be obtained by direct scaling and a power function should be obtained by indirect scaling if our assumption is expanded mathematically.

Algorithms↗

PubMed1996

[A course of pirarubicin vesical irrigation at thirty mg effectively prevents post-TUR recurrence of superficial bladder cancer].

In order to study its safety and anti-cancer dose-effectiveness in the prevention of cancer recurrence, two groups of patients having superficial bladder cancer (TUR-Bt) had their bladder intravesically irrigated post-surgically with 20 or 30 mg aliquots of (2''R)-4'-0-tetrahydropyranyl-adriamycin (THP). A total of 74 patients with bladder cancer were entered in the study. Four cases proved ineligible, and 30 could not complete the planned treatment. THP vesical irrigation of 14-17 sessions was regarded as a condition for eligibility: Clinical evaluation was feasible with 19 patients of 20 mg and 21 of 30 mg THP. Non-recurrence rates at 1, 2, 3 and 4 years were 89.5, 53.3, and 26.6%, respectively, for the 20 mg group, and 95.2, 84.3, 75.9 and 75.9%, respectively, for the 30 mg THP group. The incidence of side effects appeared slightly greater in the 30 mg THP group than in the 20 mg group, and there were no systemic adverse reactions. Topical reaction of cystitis was noted to be as low as 12.5%. Thus, THP vesical irrigations at 30 mg were found tolerable and effective for the prevention of local recurrence following TUR-Bt.

Administration, Intravesical↗