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Biomedical subjects

T Oki

Publications and source records attributed to T Oki.

At least 217 records · Page 12Linked to original sources
PubMed1993

[Evaluation of pulmonary venous flow patterns in left heart failure: a study using transesophageal Doppler echocardiography].

Pulmonary venous flow (PVF) patterns in left heart failure were evaluated using transesophageal pulsed Doppler echocardiography in 30 patients with dilated hearts (DH) and 30 normal subjects. Eighteen patients had myocardial infarction and 12 patients had dilated cardiomyopathy. The diagnostic criteria by using M-mode echocardiography were left ventricular end-diastolic dimensions (LVDd) of 5.5 cm or more and % LV fractional shortening (%FS) of less than 30%. Peak velocities of the first systolic (PVS1) and second systolic (PVS2) forward waves of PVF, %FS and total amplitude of mitral annular motion in the patient group were significantly decreased compared with the normal group. However, there were no differences in these parameters between the 22 patients (DH-1 group) with a mean pulmonary capillary wedge pressure (PCWP) of less than 18 mmHg and 8 patients (DH-2 group) with a PCWP of 18 mmHg or greater. Peak velocities of the diastolic forward wave of PVF and the early diastolic wave (D) of the LV inflow velocity in the DH-1 group were significantly decreased, and the peak velocity of the atrial contraction wave (A) of the LV inflow velocity was increased compared with those of the normal group. D of the LV inflow velocity, peak velocity of the diastolic forward wave, and peak velocity of the atrial systolic backward wave of the PVF in the DH-2 group were significantly increased compared with those of the DH-1 group. Significant positive correlations were observed between peak velocity of the diastolic forward wave and D or PCWP in the patient group, but the latter relationship was not linear. The A/D ratio of the LV inflow velocity was significantly decreased, and the ratio of the amplitudes of atrial contraction wave to total vertical deflection on the apexcardiogram of the DH-2 group were significantly increased compared with those of the DH-1 group. A patient with extensive myocardial infarction associated with development of severe LV dysfunction (PCWP = 23 mmHg) and a "pseudonormalization" pattern of LV inflow velocity demonstrated markedly increased peak velocities of the diastolic and atrial systolic forward wave, and decreased PVS2. However, the peak velocities of the diastolic and atrial systolic forward wave were decreased, and that of PVS2 was increased with fair improvement of LV dysfunction (PCWP = 10 mmHg) and with compensatory augmentation of the atrial contraction wave A of LV inflow velocity.(ABSTRACT TRUNCATED AT 400 WORDS)

Cardiomyopathy, Dilated↗
PubMed1993

Morphological changes of Candida albicans induced by BMY-28864, a highly water-soluble pradimicin derivative.

The time course of BMY-28864-dependent morphological changes in Candida albicans A9540 was studied by electron microscopy. Scanning electron microscopy revealed that BMY-28864 often induced cell surface deformations such as abnormal swelling and bulging around budding sites and bud scars. The cell membrane damage was visualized by freeze-fracturing technique as deep pit-like invaginations. Transmission electron microscopy with thin-sectioned specimens also demonstrated that BMY-28864 induced cell membrane invaginations together with cell membrane detachment from the cell wall, nuclear membrane fragmentation and mitochondrial aberration. Statistical sequence analysis of the prominent BMY-28864-dependent morphological changes of the yeast cells led to the conclusion that BMY-28864 first attacked the cell membrane and then caused disintegration of other intracytoplasmic organelles, resulting in the lethal effect.

Anthracyclines↗
PubMed1993

[One family having 5 members with hypertrophic cardiomyopathy with similar pattern of left ventricular inflow and distribution of hypertrophy].

We examined, in one family, 5 cases of hypertrophic cardiomyopathy (HCM) with a similar pattern of left ventricular inflow (LVIF) and distribution of hypertrophy. Its clinical background and significance were discussed. Because a variety of morphologic expressions of HCM may be observed in the same family, distribution of left ventricular hypertrophy (LVH) varies in even first-degree relatives of the family. In all five cases in this study, however, LVH was localized between the anterior wall and the interventricular septum. On the other hand, typical pattern of LVIF in HCM is "decreased peak velocity and prolonged deceleration time of the early diastolic wave (E), and compensatory augmentation of the atrial contraction wave (A)". All of the five cases in this study had a pattern of three characteristic peaks of LVIF, which showed the mid-diastolic wave between the E and A waves. The above findings suggested that the myocardial characteristics of the five cases in this family were very similar, and could be important clues clarifying the mode of inheritance of HCM.

Adult↗
PubMed1992

Inhibition of melanogenesis by BMY-28565, a novel compound depressing tyrosinase activity in B16 melanoma cells.

The mechanism of a novel melanin synthesis inhibitor, BMY-28565, was studied using mouse B16 melanoma cells. This compound was active in depressing the intracellular accumulation of melanin with an IC50 of 5 microM. At dose levels causing no cytotoxicity, the melanolytic effect of this compound was correlated strongly with depression of the enzymatic activity of tyrosinase (monophenol oxygenase, EC 1.14.18.1), the key enzyme in the melanin synthesis pathway. Transcription of the tyrosinase gene was not inhibited by BMY-28565, as determined by RNA blotting analysis. BMY-28565 and three other active derivatives of this compound caused increased glycosylation of proteins in B16 melanoma cells, as assessed by radioactive mannose incorporation. It is, thus, suggested that the mechanism of inhibition of tyrosinase might be related to modifications of the sugar moiety of this enzyme or of a protein(s) that is essential for the expression of its enzymatic activity.

Animals↗
PubMed1992

Xanthofibroma of the adrenal gland.

The authors report on a 43-year-old woman who had undergone unilateral adrenalectomy for a right suprarenal mass. The removed specimen was histopathologically defined as xanthofibroma, a hitherto unpublished adrenal tumour. The connective tissue protein of this rare tumour contained great amounts of collagen, non-collagenous protein and elastin. The significance of such abnormal proliferation of fibrous tissue and the conventional sonographic and CT features of this neoplasm are discussed.

Adrenal Gland Neoplasms↗
PubMed1992

A sero-epidemiological study on mother-to-child transmission of HTLV-I in southern Kyushu, Japan.

In vertical transmission of HTLV-I the duration of breast-feeding seems to be an important risk factor. In this study, we made prospective and retrospective surveys on the rate of vertical transmission of HTLV-I in infants and their siblings born to HTLV-I seropositive mothers. The results obtained were as follows. (1) In the prospective study, 885 of the 16,283 pregnant women examined were HTLV-I seropositive, and the seropositive rate was 5.4%. The seroconversion rates of short-term (< 7 months) and long-term (> or = 7 months) breast-feeders were 3.8% (1/26 cases) and 25.0% (1/4 cases) respectively, and the rate of bottle-feeders was 5.6% (10/177 cases). Short-term breast-feeding tended to yield a lower seroconversion rate of infants. In addition, the seroconversion rate of short-term breast-feeders was nearly equal to that of bottle-feeders: 3.8% vs. 5.6%. (2) In the retrospective study, the seroconversion rates of short-term and long-term breast-feeders in their siblings were 4.5% (3/67 cases) and 14.0% (19/136 cases) respectively. There was a significant difference between the 2 groups (p < 0.01). Thus, the results of our retrospective and prospective studies suggest that short-term breast-feeding might lessen the risk of breast-milk-borne transmission of HTLV-I from carrier mothers to their children.

Adult↗
PubMed1992

Preparation and antitumor activity of 2''-O-, 3''-O- and 2'',3''-di-O-substituted derivatives of etoposide.

The 2''-O-, 3''-O- and 2'',3''-di-O-substituted derivatives (4a--p) of etoposide were prepared by nucleophilic substitution of 4'-O-benzyloxycarbonyletoposide (2) followed by deprotection. Controlled reaction (a limited amount of reagents and low temperature) was required for preparing the mono-O-substituted derivatives. In terms of ED125 values, doses which show 125% of T/C against P388 leukemia in mice, both the 2''-O-acetate (4a, ED125 = 0.18 mg/kg) and 3''-O-acetate (4b, 0.23 mg/kg) were nearly as active as etoposide (1, 0.19 mg/kg), while the 2'',3''-di-O-acetate (4c, 1.9 mg/kg) was somewhat less potent. In the replacement with other substituents, antitumor activity of the 2''-O-substituted derivatives was affected much more by the difference of the substituents as compared with that of the corresponding 3''-O-substituted derivatives. In the 2'',3''-di-O-substituted derivatives, the activity was decreased additively on the substituents.

Animals↗
PubMed1992

Protective effect of eurystatins A and B, new prolyl endopeptidase inhibitors, on scopolamine-induced amnesia in rats.

Eurystatins A and B, which are produced by Streptomyces eurythermus R353-21, potently inhibited Flavobacterium prolyl endopeptidase (PED) with IC50 values of 0.004 and 0.002 micrograms/ml, respectively, while no inhibition was observed against another 5 proteases, even at 100 micrograms/ml. The protective effect of eurystatins A and B against scopolamine (3 mg/kg, i.p.)-induced amnesia in rats was evaluated by the step-through one-trial passive avoidance method. When administered i.p. 30 min prior to the acquisition trial, both eurystatins A, at 2-8 mg/kg, and B, at 4-8 mg/kg, significantly protected rats from the amnesic effect of scopolamine without behavioral side effects.

Amino Acid Sequence↗
PubMed1992

Sultriecin, a new antifungal and antitumor antibiotic from Streptomyces roseiscleroticus. Production, isolation, structure and biological activity.

Streptomyces roseiscleroticus L827-7 (ATCC 53903) produced a novel antifungal and antitumor antibiotic, sultriecin. It exhibited in vitro antifungal activity and potent in vivo antitumor activity against P388 and L1210 leukemias, and B16 melanoma. Sultriecin is composed of several unique structural units; a conjugated triene, an alpha,beta-unsaturated delta-lactone, and a sulfate functionality.

Animals↗
PubMed1992

Butyrolactols A and B, new antifungal antibiotics. Taxonomy, isolation, physico-chemical properties, structure and biological activity.

New antifungal antibiotics, butyrolactols A and B, have been isolated from the culture broth of Streptomyces rochei S785-16. They are novel type of molecules containing a common 2,3-dihydroxybutyrolactone nucleus substituted with a different long hydroxyalkyl side chain. Butyrolactol A showed good antifungal activity against Aspergillus fumigatus and Trichophyton mentagrophytes, and moderately inhibited the growth of yeasts.

4-Butyrolactone↗
PubMed1992

New antiviral antibiotics, cycloviracins B1 and B2. I. Production, isolation, physico-chemical properties and biological activity.

Kibdelosporangium albatum No. R761-7 (ATCC 55061) produced new antiviral antibiotics, cycloviracins B1 and B2. They show weak activity against Gram-positive bacteria and potent antiviral activity against herpes simplex virus type 1. Unique acylsaccharide structures were established for cycloviracins B1 and B2 by degradation and spectroscopic analysis.

Actinomycetales↗
PubMed1992

New antiviral antibiotics, cycloviracins B1 and B2. II. Structure determination.

The structures of novel antiviral antibiotics, cycloviracins B1 and B2 have been determined by means of chemical and spectroscopic methods including 2D NMR correlation spectroscopy. The antibiotics are unique macrocyclic diesters consisting of two D-glucoses, three 2-O-methyl-D-glucoses and two (C24 and C26) hydroxy fatty acids.

Actinomycetales↗
PubMed1992

Synthesis and antifungal activities of pradimicin derivatives, modification at C4'-position.

The 4'-N-alkyl(1 approximately 10) and 4'-N-acyl derivatives (11 approximately 21) of pradimicins (PRMs) were synthesized by trimethylsilylation of PRMs A, C and FA-1 followed by condensation with appropriate alkylating and acylating agents. The 4'-hydroxy derivatives (23 and 24) were synthesized from PRM FA-2 in a 3-step sequence. Among these compounds, the 4'-N-carboxyl substituted alkyl (1, 5, 8 and 10), 4'-N-formyl (11) and 4'-axial-hydroxy (23) derivatives retained the antifungal activity of the parent compounds and showed great improvement in water solubility.

Anthracyclines↗
PubMed1992

Epoxomicin, a new antitumor agent of microbial origin.

An actinomycete strain No. Q996-17 produced a novel compound, epoxomicin, which exhibited in vivo antitumor activity against B16 melanoma. Structural studies indicated that it is a new member of the epoxy-beta-aminoketone group, and is closely related to eponemycin.

Actinomycetales↗