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Biomedical subjects

T Okano

Publications and source records attributed to T Okano.

At least 19 recordsLinked to original sources
PubMed1992

Cone visual pigments are present in gecko rod cells.

The Tokay gecko (Gekko gekko), a nocturnal lizard, has two kinds of visual pigments, P467 and P521. In spite of the pure-rod morphology of the photoreceptor cells, the biochemical properties of P521 and P467 resemble those of iodopsin (the chicken red-sensitive cone visual pigment) and rhodopsin, respectively. We have found that the amino acid sequence of P521 deduced from the cDNA was very similar to that of iodopsin. In addition, P467 has the highest homology with the chicken green-sensitive cone visual pigment, although it also has a relatively high homology with rhodopsins. These results give additional strength to the transmutation theory of Walls [Walls, G. L. (1934) Am. J. Ophthalmol. 17, 892-915], who proposed that the rod-shaped photoreceptor cells of lizards have been derived from ancestral cone-like photoreceptors. Apparently amino acid sequences of visual pigments are less changeable than the morphology of the photoreceptor cells in the course of evolution.

Amino Acid Sequence↗
PubMed1992

Primary structures of chicken cone visual pigments: vertebrate rhodopsins have evolved out of cone visual pigments.

The chicken retina contains rhodopsin (a rod visual pigment) and four kinds of cone visual pigments. The primary structures of chicken red (iodopsin) and rhodopsin have been determined previously. Here we report isolation of three cDNA clones encoding additional pigments from a chicken retinal cDNA library. Based on the partial amino acid sequences of the purified chicken visual pigments together with their biochemical and spectral properties, we have identified these clones as encoding the chicken green, blue, and violet visual pigments. Chicken violet was very similar to human blue not only in absorption maximum (chicken violet, 415 nm; human blue, 419 nm) but also in amino acid sequence (80.6% identical). Interestingly, chicken green was more similar (71-75.1%) than any other known cone pigment (42.0-53.7%) to vertebrate rhodopsins. The fourth additional cone pigment, chicken blue, had relatively low similarity (39.3-54.6%) in amino acid sequence to those of the other vertebrate visual pigments. A phylogenetic tree of vertebrate visual pigments constructed on the basis of amino acid identity indicated that an ancestral visual pigment evolved first into four groups (groups L, S, M1, and M2), each of which includes one of the chicken cone pigments, and that group Rh including vertebrate rhodopsins diverged from group M2 later. Thus, it is suggested that the gene for scotopic vision (rhodopsin) has evolved out of that for photopic vision (cone pigments). The divergence of rhodopsin from cone pigments was accompanied by an increase in negative net charge of the pigment.

Amino Acid Sequence↗
PubMed1992

Relocation and distinct subcellular localization of p34cdc2-cyclin B complex at meiosis reinitiation in starfish oocytes.

M phase promoting factor (MPF) is a major element controlling entry into the M phase of the eukaryotic cell cycle. MPF is composed of two subunits, p34cdc2 and cyclin B. Using indirect immunofluorescence staining with specific antibody against starfish cyclin B, we monitored the dynamics of the subcellular distribution of MPF during meiosis reinitiation in starfish oocytes. We found that all of the cyclin B is already associated with p34cdc2 in immature oocytes arrested at the G2/M border and that this inactive complex is present exclusively in the cytoplasm. After its activation, part of the p34cdc2-cyclin B complex moves into the germinal vesicle before nuclear envelope breakdown, independently of either microtubules or actin filaments. Thereafter, some part of the complex accumulates in the nucleolus and condensed chromosomes. Another portion of the complex accumulates on meiotic asters and spindles, while the rest is still present throughout the cytoplasm. As these patterns of localization are detected in the detergent-extracted oocytes, we propose at least four distinct subcellular states of the p34cdc2-cyclin B complex: freely soluble, microtubule-associated, detergent-resistant cytoskeleton-associated and chromosome-associated. Thus, in addition to the intramolecular modification of p34cdc2-cyclin B complex, its intracellular relocation plays a key role in promoting the M phase.

Animals↗
PubMed1992

Blood compatibility of SPUU-PEO-heparin graft copolymers.

Biological responses to heparinized segmented polyurethaneurea (SPUU-PEO-Heparin) were evaluated in vitro and ex vivo. In vitro assays involved plasma protein adsorption, platelet adhesion, and release reaction studies. In addition, an ex vivo rabbit arterio-artery (A-A) shunt experiment was also performed to measure occlusion times of the heparinized surfaces. All SPUU-PEO-Heparin surfaces demonstrated less protein adsorption than Biomer and protein adsorption patterns similar to SPUU-PEO surfaces. Platelet adhesion and release studies demonstrated that both SPUU-PEO-Heparin and SPUU-PEO surfaces adsorbed less platelets and inhibited platelet release, as compared to Biomer. These findings correlated with reduction in protein adsorption observed for the modified surfaces. In low flow rate ex-vivo A-A shunt experiments, all heparinized surfaces prolonged occlusion time longer than controls. However, SPUU-PEO surfaces did not prolong occlusion time when compared to Biomer, although these surfaces suppressed protein adsorption and platelet interaction in vitro. The improved blood compatibility of SPUU-PEO-Heparin surfaces attest to the usefulness of this approach in improving the blood compatibility of blood contacting surfaces.

Adsorption↗
PubMed1992

Sequential instillation therapy with mitomycin C and adriamycin for superficial bladder cancer.

Intravesical chemotherapy involving the sequential instillation of mitomycin C (MMC) and Adriamycin (ADM) was performed in 40 patients with superficial bladder cancer (pathological stages Ta and T1). In all, 20 mg MMC on day 1 and 30 mg ADM on day 2 were instilled into the bladder. This treatment was repeated weekly for 6 consecutive weeks and then monthly for 22 months in cases patients who did not experience serious side effects. A total of 20 patients were treated for multiple recurrences, and the efficacy was evaluated. In all, 9 subjects (45%) achieved a complete response and 6 (30%) showed a partial response, for an overall response rate of 75%. The other 20 patients, including 9 with primary multiple or high-grade tumors and 11 with recurrent tumors, received prophylactic instillation therapy after undergoing transurethral resection (TUR) of their lesions. Of the 9 primary cases, 3 recurred at 19, 8, and 3 months after TUR, respectively, whereas 6 showed no recurrence over a mean follow-up period of 14 months. Of the 11 recurrent cases, the 100-patient-month recurrence rate of 11.9 obtained prior to this treatment fell to 1.4 after the start of therapy. Chemical cystitis was observed in 20 of the 40 patients treated, but the symptoms were transient and tolerable.

Administration, Intravesical↗
PubMed1992

Endocrine study of the maternity blues.

The relationship between several psychological variables and adrenocortical function of the blues is examined in a prospective study of 47 Japanese women. Psychological measures, including the psychiatric interview and assessment of the Schedule for Affective Disorders and Schizophrenia (SASD), the Research Diagnostic Criteria (RDC) and self-rating scales, were administered at the 36th week of pregnancy, on the 3rd or 4th day postnatal and one month after delivery. Twelve subjects (25.5%) were diagnosed as having the blues on the Stein's scale. Women who developed the blues had significantly higher serum bound cortisol than the non-blues group. No significant correlation was obtained between the incidence of the blues and obstetric variables. At one month after delivery, four women (8.5%) were diagnosed as postpartum depression according to the RDC. Our finding that there was no consistent obstetric factor which predisposes women to develop the blues support the hypothesis that hyperadrenocorticalism is important in the genesis of this syndrome.

Adrenal Cortex Function Tests↗
PubMed1992

Hydrogels: swelling, drug loading, and release.

Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. The desired kinetics, duration, and rate of solute release from hydrogels are limited to specific conditions, such as hydrogel properties, amount of incorporated drug, drug solubility, and drug-polymer interactions. This review summarizes the compositional and structural effects of polymers on swelling, loading, and release and approaches to characterize solute release behavior in a dynamic state. A new approach is introduced to compensate drug effects (solubility and loading) with the release kinetics by varying the structure of heterogeneous polymers. Modulated or pulsatile drug delivery using functional hydrogels is a recent trend in hydrogel drug delivery.

Drug Carriers↗
PubMed1992

Determination of trace elements in steel by laser ablation inductively coupled plasma mass spectrometry.

A rapid quantitative analysis of the trace elements in steel by laser ablation inductively coupled plasma mass spectrometry is described. The conditions for laser ablation and normalization methods to improve the analytical precision are given. The optimum conditions for laser ablation were achieved when the ion yield was a maximum at the focus position in the fixed Q pulse mode, and above the focus position in the Q-switched pulse mode. It was found that the fixed Q pulse mode was most suitable for the determination of trace metal elements in steel, and that the Q-switched pulse mode was most suitable for both non-metallic elements and elements with a high boiling-point. In order to improve the analytical precision for those elements with a strong background intensity, normalization methods with both the matrix ion, 57Fe+, and 38Ar+ are proposed.

Mass Spectrometry↗
PubMed1992

Proteus syndrome: report of the first Japanese case with special reference to differentiation from Klippel-Trenaunay-Weber syndrome.

This is the first report of a Japanese girl with Proteus syndrome. She presented with growth acceleration and precocious development of the left breast as well as macrodactyly, hemihypertrophy, a subcutaneous preaxillary mass, portwine stains, connective tissue nevi, and a depigmented macule. All these abnormalities were confined to the left side of her body. Although most of the manifestations fit those of Proteus syndrome, the presence of the portwine stains and hemihypertrophy also suggested Klippel-Trenaunay-Weber syndrome. The findings in our patient suggest that the most important characteristic distinguishing Proteus syndrome from Klippel-Trenaunay-Weber syndrome is the presence of functional abnormalities such as a growth spurt and precocious breast development. Proteus syndrome may be genetically different from the Klippel-Trenaunay-Weber syndrome.

Child, Preschool↗
PubMed1992

Photosensitivities of iodopsin and rhodopsins.

The relative photosensitivity and the molar extinction coefficient of a highly purified iodopsin (chicken red sensitive cone visual pigment) solubilized in a mixture of 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate and phosphatidylcholine (CHAPS-PC) were measured using bovine rhodopsin solubilized in 2% digitonin as a standard and compared with those of chicken and bovine rhodopsins. The photosensitivity obtained (1.08) was close to those of rhodopsins (chicken, 1.04; bovine, 0.99) in CHAPS-PC. The molar extinction coefficient of iodopsin (47,200) was 1.15-1.17 times higher than those of rhodopsins (chicken, 40,500; bovine, 41,200). The oscillator strength of iodopsin (0.60) calculated from the extinction coefficient was nearly identical to that of chicken rhodopsin (0.61), suggesting that the chromophore of iodopsin is similar in configuration to rhodopsin. In contrast, the difference in quantum yield between iodopsin (0.62) and chicken rhodopsin (0.70) suggests that the chromophore-opsin interaction after absorption of a photon by the chromophore may be different.

Animals↗
PubMed1992

Surface-modulated skin layers of thermal responsive hydrogels as on-off switches: II. Drug permeation.

'On-off' regulation of drug permeation through membranes in response to external temperature change has already been achieved using thermosensitive copolymers of N-isopropyl acrylamide (IPAAm) with butyl methacrylate (BMA). Increasing temperature induced formation of a dehydrated polymeric surface skin layer that stopped drug permeation. In this study, to control 'on-off' permeability of a drug, the polymer surface shrinking process was regulated by changing the length of alkyl side chain of the copolymer methacrylate component. Permeation experiments with indomethacin were performed in response to stepwise temperature changes between 20 and 30 degrees C with copolymers of IPAAm with BMA, hexyl methacrylate (HMA), and lauryl methacrylate (LMA). Burst permeation was found at the initial stage of the second 'on' period for both poly(IPAAm-co-HMA) and poly(IPAAm-co-LMA). These results suggest that drug diffuses during 'off' periods to change the concentration profile in the polymer gel. Polymer surface skin formation maintains a localized high water content inside the polymer gel even if drug permeation stops. The length of the alkyl side chain is an important parameter to control 'on-off' permeability of drug.

Acrylic Resins↗
PubMed1992

Surface characterization of 2-hydroxyethyl methacrylate/styrene copolymers by angle-dependent X-ray photoelectron spectroscopy and static secondary ion mass spectrometry.

The surface composition and structure of three structurally distinct amphiphilic copolymers of 2-hydroxyethyl methacrylate (HEMA) and styrene have been examined with angle-dependent X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS). The phase-separated block copolymer made by anionic living polymerization, HSH-A50, showed significant surface enrichment of styrene. The outermost 2-3 A appeared to be approximately 100% styrene, with the styrene concentration decreasing to its bulk value at a depth of approximately 50 A from the surface. However, HEMA was detected in the outer 20 A of this copolymer. The presence of HEMA in the surface region implies this copolymer may undergo significant restructuring when hydrated in a hydrophilic environment (as opposed to the hydrophobic environment in which the sample was prepared and analyzed). The phase-separated block copolymer made by telechelic coupling of free radical polymerized functionalized oligomers, HSH-B60, showed only slight styrene enrichment at the surface. Both HEMA and styrene were detected at all sampling depths, including the outermost surface layer, consistent with the presence of discrete HEMA and styrene domains at the copolymer surface. Since both components are already present at the surface under hydrophobic conditions, the degree of restructuring this copolymer may undergo upon hydration should be minor. The random HEMA--styrene copolymer made by conventional free radical initiation techniques, HS-RAN50, had a surface composition that was similar to the bulk composition and independent of depth, as expected for a homogeneously mixed copolymer film.

Biocompatible Materials↗
PubMed1992

Metabolism of orally administered ergosterol and 7-dehydrocholesterol in rats and lack of evidence for their vitamin D biological activity.

Metabolism of orally administered ergosterol (Erg) and 7-dehydrocholesterol (7-DHC) in rats and their vitamin D biological activity were investigated. Most of orally administered Erg and 7-DHC were excreted in feces and the remaining sterols were absorbed through intestine. The absorbed sterols were not transported in skin as the intact forms but metabolized into brassicasterol and cholesterol, respectively, within 25 h. Neither increment of intestinal calcium absorption nor plasma calcium concentrations were observed by oral administration of Erg and 7-DHC to vitamin D-deficient rats. Therefore, we have concluded that orally administered Erg and 7-DHC have no vitamin D biological activity.

Administration, Oral↗
PubMed1992

[Incidence of renal cell carcinoma in Chiba Prefecture, Japan; ten years experience].

Many reports about the increase of renal cell carcinoma patients have been published in Japan recently, however, the real fluctuations in the total number of patients in relation to the change of population have not been reported yet. Most of the patients with renal cell carcinoma in the last 10 years were examined in Chiba prefecture, which has a population of about five million and 25 active urological offices. Histologically confirmed cases were investigated by sending questionnaire letters. The items were as follows; sex, age, address, occupation, family history, past history, symptoms, examination methods that first detected the tumor, operation date, tumor diameter and clinical stage. Twenty two offices returned answers and 560 cases who lived in Chiba were found to have renal cell carcinoma from 1980 to 1989. Yearly incidence rates per 100,000 persons demonstrated a significant increase from 0.32 to 2.07. Small, asymptomatic and low stage cancers have been increasing rapidly, however, the rate of metastatic disease has not shown any decrease. The main cause of rapid increase seems to be attributed to progress in diagnostic methods and increase of early detection, but the possibility of an increase in some carcinogenic factors can not be ruled out.

Adult↗