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Biomedical subjects

S Kurihara

Publications and source records attributed to S Kurihara.

At least 19 recordsLinked to original sources
PubMed1992

CD8+ cutaneous anaplastic large-cell lymphoma: report of two cases with immunophenotyping, T-cell-receptor gene rearrangement and electron microscopic studies.

Two cases are reported of cutaneous anaplastic large-cell lymphoma with the suppressor/cytotoxic (CD8) phenotype. In both cases there was a solitary skin tumour in which there was a dense infiltrate with large irregularly shaped cells which on immunophenotyping expressed CD8. DNA hybridization analysis showed rearrangements of the T-cell-receptor gene in both cases.

Aged↗
PubMed1992

Changes in the microvasculature after mechanical pressure on the hamster cheek pouch.

The reaction of the microvasculature in the periodontal ligament to mechanical pressure is considered a very important phenomenon with respect to the biological background to orthodontic tooth movement. For clarification of the microvascular reaction to mechanical pressure, an experimental model that incorporated a hamster cheek pouch was established. This in vivo model solves some of the problems of other experimental models of the microvasculature of the periodontal ligament. Blood plasma permeation in this model was examined by means of a blue dye (pontamine sky blue), and histological observation was performed by light and transmission electron microscopy. Increased vascular permeability was observed within 30 min after removal of the mechanical stimulation. The threshold weight resulting in dye leakage was between 1 and 5 g applied for 60 min. From the histological observations, some large gaps between the endothelial cells in venules were found, while most basement membranes remained undisturbed. These observations suggest that the plasma leakage was due to mild traumatic injury to the endothelial cells. Both leukocytes and platelets were observed in the gaps between the endothelial cells in the venule. These types of microvascular reactions to mechanical pressure could initiate tissue changes in the periodontal ligament during orthodontic tooth movement.

Animals↗
PubMed1991

Time-resolved synchrotron X-ray diffraction studies of a single frog skeletal muscle fiber. Time courses of intensity changes of the equatorial reflections and intracellular Ca2+ transients.

Time-resolved X-ray equatorial diffraction studies on a single frog skeletal muscle fiber were performed with a 10 ms time resolution using synchrotron radiation in order to compare the time courses of the molecular changes of contractile proteins and the intracellular Ca2+ transient during an isometric twitch contraction at 2.7 degrees C. Measurements of the Ca2+ transient using aequorin as an intracellular Ca2+ indicator were conducted separately just before and after the X-ray experiments under very similar experimental conditions. The results, which showed a similar time course of tension to that observed in the X-ray experiment, were compared with the aequorin light signal, tension and the intensity changes of the 1,0 and 1,1 equatorial reflections. No appreciable change in both reflection spacings indicated that the effect of internal shortening of the muscle was minimized during contraction. The intensity change of the equatorial reflections generally occurred after the aequorin light signal. In the rising phase, the time course of increase in the 1,1 intensity paralleled that of the rise of the light signal and the intensity peak occurred 20-30 ms after the peak of the light signal. The decrease in the 1,0 intensity showed a time course similar to that of tension and the intensity minimum roughly coincided with the tension peak, coming at 80-90 ms and about 60 ms after the peaks of the light signal and the 1,1 intensity change, respectively. In the relaxation phase, the 1,1 intensity seemed to fall rapidly just before the tension peak and then returned to the original level in parallel with the decay of tension. The 1,0 intensity returned more slowly than the tension relaxation. Thus, the change of the 1,1 intensity was faster than that of the 1,0 intensity in both the rising and relaxation phases. When the measured aequorin light signal was corrected for the kinetic delay of the aequorin reaction with a first-order rate constant of either 50 or 17 s-1, the peak of the corrected light signal preceded that of the measured one by approx. 30 ms. Thus, the peak of the Ca2+ transient appeared earlier than the peaks of the 1,1 and 1,0 intensity changes by 50-60 and 110-120 ms, respectively. The time lag between the extent of structural change and the Ca2+ transient is discussed in relation to the double-headed attachment of a cross-bridge to actin.

Aequorin↗
PubMed1991

Abnormal expression of blood group-related antigens in uterine endometrial cancers.

The expression of A, B, and H group antigens, Lewis group antigens (Lewis(a), Lewis(b), Lewis(x), and Lewis(y)), and Lc4 and nLc4 antigens, the precursor antigens of both groups, was examined immunohistochemically with monoclonal antibodies in 9 normal endometria, 6 endometrial hyperplasias, and 31 endometrial cancers. 1) A, B and/or H antigens were detected in endometrial cancers at an incidence of 51.6%, while no distinct localization of these antigens was observed in normal endometria. H antigen, the precursor of A and B antigens, was particularly frequently detected in endometrial cancers. 2) An increased rate of expression of Lewis group antigens, particularly Lewis(b) antigen, was observed in endometrial cancers compared with its expression in normal endometria. 3) Lc4 and nLc4 antigens were detected in endometrial cancers at rates of 41.9% and 38.7%, respectively, these expressions being increased compared with those in normal endometria. 4) These results suggest that a highly abnormal expression of blood group-related antigens in endometrial cancers occurs not only at the level of A, B, and H antigens and Lewis group antigens, but also at the level of their precursor Lc4 and nLc4 antigens. 5) Lewis(a), Lewis(b), and Lc4 antigens, built on the type-1 chain, are more specific to endometrial cancers than their respective positional isomers, Lewis(x), Lewis(y), and nLc4 antigens, built on the type-2 chain.

ABO Blood-Group System↗
PubMed1991

Cross-bridge movement in fast and slow skeletal muscles of the chick.

1. Fast (posterior latissimus dorsi, PLD) and slow (anterior latissimus dorsi, ALD) muscles of the chick were studied by time-resolved X-ray diffraction using a synchrotron radiation source. 2. In both muscles and at both 20 and 30 degrees C, intensities of the X-ray equatorial reflections changed faster than tension at the beginning of tetanus. When the intensity change was converted into the mass transfer from the thick to the thin filament, the difference between the half-rise times of the transfer and tension development at 20 degrees C was 140 ms in ALD and 37 ms in PLD. At 30 degrees C it was 110 ms and 10-20 ms for ALD and PLD respectively. 3. These results indicate that in the early stage of contraction, some of the myosin heads in the vicinity of the thin filament are developing little or no tension, and suggest that the fast and slow muscles differ in the transition rate of myosin heads from the state of attachment with low tension to that with high tension.

Actins↗
PubMed1991

Vitamin D3 metabolites increase [Ca2+]i in rabbit renal proximal straight tubule cells.

Vitamin D metabolites exert both acute and chronic influences on proximal tubule function. To further evaluate vitamin D action on the kidney, we examined the immediate effects of vitamin D metabolites on cytoplasmic calcium ion concentration [( Ca2+]i), using fura-2 and patch-clamp method in cultured proximal straight tubule cells of rabbit kidney. 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] and 25-hydroxyvitamin D3 [25(OH)D3] evoked a transient rise in [Ca2+]i, and 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] caused a sustained rise in [Ca2+]i; all effects were dose dependent. [Ca2+]i transient, evoked by 1,25(OH)2D3 alone, was abolished in Ca(2+)-free media. Pretreatment of cells in Ca(2+)-free media with caffeine (4 mM) or ryanodine (1 microM) to deplete Ca2+ store of endoplasmic reticulum or with TMB-8 (5 mM) to block Ca2+ release from storage blunted the effect of 25(OH)D3 on [Ca2+]i but not of 24,25(OH)2D3. Data were also supported by activities of Ca-dependent K channel and show that these three vitamin D metabolites in pharmacological doses increase [Ca2+]i of proximal tubule cells from different sources.

24,25-Dihydroxyvitamin D 3↗
PubMed1991

Intracellular calcium signals measured with fura-2 and aequorin in frog skeletal muscle fibers.

Intracellular Ca(2+)-related optical signals during and after contraction (twitch and tetanus) were measured in single frog skeletal muscle fibers with fura-2 and aequorin. In twitch response, the peaks of [Ca2+]i estimated from the in vitro calibrations of fura-2 and aequorin were significantly different (0.5 microM for fura-2 and 5 microM for aequorin). Even 30s after twitch response, the fura-2 fluorescence ratio (F340/F380) signal did not recover to the resting level before stimulation. When the stimulation frequency was increased, an increase in the resting fura-2 ratio signal became obvious and after the cessation of stimulation this increase gradually recovered to the level before stimulation. After tetanus (50 Hz for 1 s), a higher fura-2 ratio signal than that before stimulation was sustained longer than 90 s. These results indicate that the dissociation of the released Ca2+ from the intracellular Ca2+ binding sites probably takes longer time than that previously reported. The present results, therefore, demonstrate that fura-2 is advantageous for qualitative monitoring of a slight change in the resting level of [Ca2+]i, which is not easily detectable with aequorin. In addition, the problems encountered in quantitative estimation of [Ca2+]i with fura-2 are also discussed.

Aequorin↗
PubMed1991

[Flow cytometric DNA analysis of uterine endometrial carcinoma].

The DNA content in individual cells from 40 cases of histopathologically normal endometria, 15 of endometrial hyperplasia and 68 of endometrial adenocarcinoma was measured by flow cytometry. An aneuploid cell population was found in 50% of malignant endometria, but in the remaining endometrial carcinomas, the flow cytometrical findings showed no difference from those of benign tissue. Aneuploidy was more common (77.8%) in poorly differentiated tumors than in highly differentiated tumors (35.5%). Two and more aneuploid cell populations were found in 8 cases of 34. The DNA indices of aneuploid tumors were classified into 3 groups: hyperdiploidy, low hyperdiploidy (DNA index range: 1.04-1.2) and high hyperdiploidy (DNA index range: More than 1.2). The proportion of tumors with a high DNA index tended to increase as tumors became less differentiated. In normal endometria the fraction of cells with DNA content corresponding to the s-phase (s-fraction) was 8 +/- 3% on average in the proliferative phase. In well differentiated diploid tumors the s-fraction was 12 +/- 6%, but in moderately and poorly differentiated tumors it was higher (16.0% and 19.0%).

Adenocarcinoma↗
PubMed1990

Modulation of Ca2+ transients and contractile properties by beta-adrenoceptor stimulation in ferret ventricular muscles.

1. The mechanism of modulation of Ca2+ transients and contraction by beta-adrenoceptor stimulation was studied in ferret ventricular muscles using aequorin to measure intracellular Ca2+. 2. Peaks of tension and light transients were increased by isoprenaline (10(-9) - 5 x 10(-7) M) which also abbreviated their time courses. 3. Time-to-peak tension was significantly shortened by 5 x 10(-9) M-isoprenaline and time-to-peak light was abbreviated by 10(-9) M-isoprenaline. 4. The time for the light to decay was shortened at 10(-9) M-isoprenaline. However, a higher concentration of isoprenaline (10(-8) M) was required for significant shortening of the half-relaxation time (TR50). 5. When isoprenaline was removed and beta-blocker (bupranolol, 1 microM) was applied, the time course of the light transients recovered but the time course of relaxation did not recover. 6. The relationship between [Ca2+]i and tension in tetanic contraction produced in the presence of ryanodine (5 microM) was shifted to the right by isoprenaline (10(-8) M). This was recovered by the replacement of isoprenaline with bupranolol (1 microM). 7. Isoprenaline (10(-7) M) added to the solution containing 20 mM [Ca2+]O and Bay K 8644 (1 microM), which produced maximal tension, caused a large light signal and enhancement of the initial phasic tension in tetanic contraction. However, the replacement of isoprenaline with bupranolol after immersing the preparation in 20 mM [Ca2+]O solution with Bay K 8644 and isoprenaline, did not significantly change the tension level, although the light signal decreased. Similar results were obtained in the ventricular muscle of young rats. 8. These results suggest that the dose dependence of modulation of the contractile element and sarcoplasmic reticulum (SR) by beta-adrenoceptor stimulation differs, and that additional factors, other than the faster Ca2+ uptake by SR and the decrease in Ca2+ sensitivity of the contractile element, might be involved in the shortening of the half-relaxation time by beta-adrenoceptor stimulation. In addition, beta-adrenoceptor stimulation does not produce a marked change in the maximal tension level.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1990

[Ca2+]i rises via G protein during regulatory volume decrease in rabbit proximal tubule cells.

Although animal cells swell in hypotonic medium, their volume is subsequently regulated by a net loss of KCl via Ca2(+)-dependent channels. A rise in intracellular free calcium ([Ca2+]i) thus appears to be an initial event in the adaptation of external tonicity, although details of this mechanism are not known. To investigate cell volume regulation, we measured [Ca2+]i (by use of fura-2) and cell diameters in single cells of cultured renal proximal convoluted tubule. We found that a rapid rise in [Ca2+]i occurred after cells were exposed to hypotonic solution (250 mosM) from 95.8 +/- 3.8 to 468.2 +/- 24 nM (n = 16). The rise in [Ca2+]i was not observed in cells exposed to Ca2(+)-free medium, and exposure to isotonic high-K or low-Na medium did not elicit a rise in [Ca2+]i, suggesting that this rise was a result of Ca2+ influx and not via voltage-dependent Ca2+ influx or decrease of Ca2+ efflux via Na(+)-Ca2+ pump. Pretreatment of cells with pertussis toxin dose dependently blocked the rise in [Ca2+]i. The hypotonic solution enhanced accumulations of inositol tris- and tetra-phosphate after a 1-min exposure. Studies that measured cell diameters suggest that recovery of cell volume may include the rise in [Ca2+]i. These data suggest that the regulatory volume decrease of proximal tubule cells involves a pertussis toxin-sensitive guanine nucleotide binding protein-operated Ca2+ influx.

Animals↗
PubMed1990

Effects of isoprothiolane and phytosterol on lipogenesis and lipolysis in adipocytes from rats of dietary fat necrosis.

To study effects of isoprothiolane and phytosterol on dietary fat necrosis, 3 groups of rats were fed hardened-tallow (HT) diet. Two groups of rats received either isoprothiolane (50 mg/kg) or phytosterol (20 mg/kg) orally once a day consecutively for 10 weeks. One group of rats received standard diet (CE-2) as a control. Fat necrotic lesions were observed in epididymal and perirenal adipose tissues from all rats in the 3 groups fed HT diet. Rats with fat necrosis were characterized by visceral type obesity and saturation in fatty acid composition of triglyceride in adipose tissue. The highest glucose conversion to total lipids was seen in adipocytes from the rats given phytosterol. There was no lipolytic response to epinephrine stimulation (1-100 microM) in adipocytes from the rats given only HT diet, while similar response of adipocytes from the 2 groups treated with either drug to those from the rats fed standard diet was observed. The levels of total saturated fatty acids of phospholipid in adipose tissue from the rats given either drug were lower than that of the rats given only HT diet. These data suggest that either drug alters fatty acid composition of phospholipid in fat cell membrane and enhances lipolysis of the cells.

Adipose Tissue↗
PubMed1990

Effects of length change on intracellular Ca2+ transients in ferret ventricular muscle treated with 2,3-butanedione monoxime (BDM).

Quick release of the right ventricular papillary muscle of ferrets, injected with aequorin, from Lmax (initial length) to 92% Lmax during twitch response produced an extra-light signal of aequorin. 2,3-Butanedione monoxime (BDM) at 10 mM decreased the peak tension to less than 10% of that in control and the light signal to 70%. In the BDM-treated muscle, the extra-light in response to the quick release did not occur. A quick stretch from Lmax to 103% Lmax, in the presence and absence of BDM, did not cause any changes in the light signal. The results indicate that the extra-light signal in the quick release is tension dependent. The tension reduction by the quick release decreases the affinity of troponin-C (Tn-C) for Ca2+ without affecting Ca2+ handling system in intact cardiac muscle.

Aequorin↗
PubMed1990

[Matrix vesicles in membranous ossification].

Calcification process in membranous ossification was examined histologically by light and electron microscopies in comparison with that in enchondral ossification. The following results were obtained: 1) In the rat tibial articular cartilage, the extracellular matrix proceeding from the transitional to the hypertrophic zone consisted of the following three layers from the proximal: the first layer in which ruthenium red positive granules were densely populated and thin collagen fibrils diffusely arranged but few matrix vesicles were observed; the second one containing numerous matrix vesicles and slightly thick collagen fibrils; and the last one in which the thick collagen fibrils were observed while matrix vesicles and ruthenium red positive granules were few. 2) In the calcified regions in the extracellular matrix of MC3T3-E1 cells, the regions of alveolar new bone formation due to orthodontic tooth movement and the calcified regions in the interparietal suture expanded mechanically in vitro, the number of matrix vesicles was less than those in the regions of enchondral ossification. 3) Ruthenium red positive granules were fewer in the regions of alveolar new bone formation after the orthodontic tooth movement than in the calcified regions of cartilage. 4) The observation on MC3T3-E1 cells revealed the two different possibilities of the processes of calcification: the calcification induced by matrix vesicles as an initiator and that directly related to mineral deposit on the collagen fibrils.

Alveolar Process↗
PubMed1990

[Long-term follow-up study of I-131 therapy for Graves' disease--index associated with late-onset hypothyroidism].

We have studied the follow-up of thyroid function in the patients with late-onset hypothyroidism and euthyroidism after I-131 therapy of hyperthyroidism. Thirty three patients who did not need the thyroid treatment until ten years after I-131 therapy were classified as euthyroid group. And eleven patients who needed the thyroid supplement of thyroid hormone for late-onset hypothyroidism were classified as hypothyroid group. Patients in both groups who required only a single dose of I-131 for successful treatment of hyperthyroidism had similar age, gland size, 24 hour I-131 uptake, pretreatment serum T3 uptake level and T4 concentration, and I-131 treatment dose. Subclinical hypothyroidism occurred in 28.6% of euthyroid group and 66.7% of hypothyroid group four months after I-131 therapy. The levels of T3 were recovered to higher than normal range at 6 months in euthyroid group, while the levels of T3 were kept within the normal range in the seventy percent of hypothyroid group. Patients who were still lower in the level of T3 uptake than normal range at 6 months had a higher incidence of late-onset hypothyroidism. Our observation showed no significant difference in the course of follow-up studies after I-131 therapy between the patients with late-onset hypothyroidism and euthyroidism.

Adult↗
PubMed1989

Binding of murine monoclonal antibodies to the active and inactive configurations of aequorin.

Murine monoclonal IgG1 antibodies (MAb), designated Aq-11 and Aq-12, were prepared against the photoprotein aequorin from jelly fish. Aequorin is a calcium-sensitive photoprotein which consists of a single polypeptide chain, apoaequorin, and a functional chromophore, coelenterazine. Native aequorin consists of two species with molecular masses of 25 and 23.5 kDa. MAb Aq-12 was found by immunoblot analysis to bind specifically to the 25 kDa species, while MAb Aq-11 reacted with the 23.5 kDa protein. Activation of apoaequorin with coelenterazine was associated with a shift of the 23.5 kDa molecule to the 25 kDa species. In contrast, treatment with calcium ions induced a shift back to the 23.5 kDa form. These changes between the active and inactive forms were identified by reactivity with MAbs Aq-11 and Aq-12. The results thus indicate that these MAbs should be useful in monitoring activation of this photoprotein.

Aequorin↗