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Biomedical subjects

M Shimizu

Publications and source records attributed to M Shimizu.

At least 991 records · Page 55Linked to original sources
PubMed1992

[Long-term effect of medical treatment in patients with chronic aortic regurgitation].

We often experience patients with chronic severe aortic regurgitation (AR) whose cardiac function significantly improves by medications, especially by vasodilator therapy. To find the factors determining the response to pharmacologic treatment, we studied 20 patients with chronic AR with dilated left ventricle (end-diastolic dimension > or = 55 mm) using echocardiography; 9 patients with significant improvement (delta Ds < or = -3 mm: improved group) and 11 without improvement (unchanged group). In the initial evaluation, systolic blood pressure and left ventricular relative wall thickness (Thd/Dd) were greater and left ventricular end-diastolic dimension was smaller in the improved group than in the unchanged group. During the follow-up period, systolic blood pressure and end-systolic wall stress decreased significantly and absolute and relative wall thickness increased significantly in the improved group, however, they remained nearly the same in the unchanged group. Significant negative correlation was observed between Thd/Dd and delta Ds. In conclusion, cardiac function in some patients with chronic AR can be improved by pharmacologic treatment, and in such cases, the Thd/Dd ratio could be a parameter of the response to pharmacologic treatment.

Adult↗
PubMed1992

[Changes in retinal blood flow volume in experimental retinal vein compression].

The authors quantitated the retinal blood flow volume during and immediately after experimental compression of the temporal retinal vein in 5 Macaca fuscata monkey eyes. The hydrogen clearance method was used to quantitate the retinal blood flow volume. After placing a microelectrode on the retinal surface, we measured the blood flow volume 4 times at a 15-minute interval. This value served as a baseline for the experiments. Next we compressed the temporal retinal vein near the disc with a 25-gauge needle with a rounded tip under guidance by an indirect ophthalmoscope. We measured the blood flow volume during compression. The compression was maintained for 3 minutes. Further blood flow determination was performed 7 minutes after release of compression and was repeated 4 times at a 15-minute interval. During compression of the temporal retinal vein, the retinal blood flow volume in the area served by the vein decreased by an average of 35%. The flow volume recovered rapidly and remained stable after release of compression. There was no reactive hyperemia. This model appears useful to elucidate the retinal circulation of branch retinal vein occlusion.

Animals↗
PubMed1992

[Blood concentrations of futraful, uracil and 5-fluorouracil (5-FU) after UFT administration in the various reconstructions after gastrectomy. Saitama UFT Research Group].

The study was undertaken in the total of 58 gastric cancer patients among which 17 of Billroth (BI), 14 of Billroth II (B II) anastomosis after subtotal gastrectomy, and 7 of jejunal interposition, 9 of double tract and 11 of Roux en Y anastomosis after total gastrectomy were included. Blood samples were taken before 200 mg of per oral UFT administration and after 1, 2, 3, 5 and 7hrs. consecutively. The blood Futraful (FT) level in the total gastrectomy groups reached peak concentration within 1hr and kept in relatively high level during the observation period of 7hrs. The time to maximum FT concentration delayed in almost of B I and a few of B II patients. The concentration curves of uracil (URA) and 5-FU were similar in shape, revealing steep increase and decrease except B I anastomosis which showed gentle course. The plotted maximum concentrations of URA and 5-FU in the every type of reconstruction showed a significant correlation in the regression line. In the analysis of AUC, URA/FT was under 10%, suggesting the longer retention of the unmetabolite type of FT and early disappearance of URA. The ratio of 5-FU/FT was indifferent in each reconstruction. 5-FU/URA was higher in subtotal rather than total gastrectomy groups. From the data obtained, blood concentration of 5-FU after UFT administration was considered to depend on the emptying status in the gastrectomies. And moreover, it depended on blood URA level, since FT from which 5-FU was derived, was kept still sufficiently remained during observation period.

Anastomosis, Roux-en-Y↗
PubMed1992

[The oral 1-25 dihydroxyvitamin D3 pulse therapy in hemodialysis patients for the early treatment of secondary hyperparathyroidism].

It is said that maintenance hemodialysis patients are already suffering from secondary hyperparathyroidism (2HPT) from early stage of chronic renal failure. The treatment of 2HPT in this stage is very important for preventing renal osteodystrophy (ROD). But many long-term dialysis patients are still afflicted with ROD although vitamin D have been used for treatment. In this study, an oral administration of 1-25 (OH)2 D3 (4 micrograms) with pulse therapy twice a week at the day before hemodialysis was started for 12 weeks. The concentration of 1-25 (OH)2D3, total calcium (Ca), ionized calcium (Ca++), alkaline phosphatase (ALP) and parathyroid hormone (PHT) in serum were measured not only before and after every 2 hours of administration a day, but also for 12 weeks after that. The peak of serum 1-25 (OH)2D3 could be sufficiently elevated after 8 hours, and the slight peak of Ca++ could be seen after 8 hours as well. But the level of total calcium could not increased. Although the level of only HS-PTH has not increased after 24 hours, a significant reduction in serum level of C-PTH, intact-PTH and HS-PTH could be recognized after 12 weeks finally. This pulse therapy was effective in reducing the serum level of PTH in this early stage from beginning hemodialysis. But, it needs further studies for the standard treatment.

Administration, Oral↗
PubMed1992

[Clinical use of the multi-purpose circuit with a soft reservoir built in inflow side in replacement of the descending thoracic aorta].

The temporary bypass circuit under centrifugal pumping is generally applied for the assisted circulation of the operation for the aneurysm of descending aorta. The estimation of the bypass flow to the abdominal viscera, however, sometimes showed inadequate when excessive bleeding happened during operation. In order to keep constant flow to the lower body, we developed a new circuit, that has soft reservoir built in inflow side of the bypass line. In 8 subjects using this circuit, we studied the usefulness of the circuit and the choice of bypass route based on changes in the hemodynamics during bypass and operative complications in relation to bypass technique. During bypass, perfusion pressure to the lower body was 70-110 mmHg and flow was maintained at more than 21/min even if massive hemorrhage occurred. Comparing arterial bypass with LV bypass, the diastolic pressure in the upper limb was significantly depressed in arterial bypass with reading of 40-50 mmHg. Furthermore, in one case of arterial bypass involving the ascending aorta, false aneurysm is found in the site of cannulation. The rectal temperature dropped with the lapse of time from 35.5 +/- 0.8 degrees C to 33.5 +/- 0.4 degrees c in 120 min. These results indicate that multi-purpose circuit is capable of promptly supplying the circulating volume and is excellent means of providing adequate circulation to the lower body even if massive hemorrhage occurred. And LV bypass should be selected first, because arterial bypass has the hazard of depressing the diastolic pressure in the upper limb and involving complications associated with the insertion of cannula.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Blood flow in the optic nervehead following intravenous administration of calcium antagonist].

The authors quantitated the blood flow of the optic nervehead after intravenous administration of calcium antagonist. The hydrogen clearance method was used to measure the blood flow after placing an electrode sensor in the optic nervehead of 9 eyes of 5 Macaca fuscata monkeys, under general anesthesia by intravenous pentobarbital sodium. 5 micrograms/kg of nicardipine, a calcium antagonist, was rapidly injected into the femoral vein. Measurement of blood flow in the optic nervehead was started 5 minutes after injection until 90 minutes at intervals of 15 minutes. A dose of 2 micrograms/kg/min nicardipine was then administered intravenously for another 90 minutes. During the experiment, intraocular pressure was maintained at 15 mmHg under continuous monitoring of systemic blood pressure. The blood flow in the optic nervehead decreased to 83% 5 minutes after injection. It increased slowly and reached the initial value 50 minutes later. It reached 108% of the initial value 80 minutes after injection. During the additional infusion of nicardipine, the blood flow decreased slowly and reached 85% of the initial value. It is concluded that the blood flow in the optic nervehead changed depending on the method, quantity and duration after injection of intravenous calcium antagonist. The blood flow decreased immediately after administration. The main cause of this phenomenon was thought to be due to decrease of perfusion pressure secondary to decrease of systemic blood pressure.

Animals↗
PubMed1992

[A case of metastatic breast carcinoma with cardiac tamponade and pleural effusion showing long survival by local treatment combined with systemic chemotherapy].

This report describes a case of metastatic breast carcinoma in a 62-year-old woman with cardiac tamponade and pleural effusion. Pericardiocentesis followed by ADM (10 mg) instillation successfully controlled cardiac tamponade. After local treatment CAF systemic chemotherapy was performed without serious complications. A long survival time of 50 months was observed. This result suggests that in this case pericardiocentesis with ADM instillation was life saving and that systemic chemotherapy prolonged life.

Breast Neoplasms↗
PubMed1992

[Myocardial perfusion and clearance of 99mTc teboroxime assessed by SPECT].

99mTc teboroxime is a new myocardial imaging agent that has characteristics of high accumulation in the heart and rapid clearance. We performed tomographic teboroxime study and compared the findings with that of 201Tl. Myocardial teboroxime clearance was calculated by dynamic single photon emission computed tomography (SPECT) using continuous repetitive rotation acquisition method. Teboroxime SPECT image was reconstructed by the three-minute data started from 4 minutes after injection. In 45 myocardial regions (15 patients), complete agreement between 201Tl and 99mTc teboroxime was obtained in 33 regions (73%), when the findings were classified as normal, ischemia and infarction. Significant delay in clearance was seen in the region of coronary stenosis (greater than or equal to 75%) compared with that in the control region (p = 0.0087 at rest, and p = 0.0385 at peak exercise by paired T test). Septum-to-lateral ratios of the clearance and myocardial initial count showed positive correlation (r = 0.743). Further clinical application of this radiopharmaceutical is expected as a new myocardial imaging agent.

Coronary Circulation↗
PubMed1992

[Multicenter clinical evaluation of red cell concentrates stored up to 6 weeks in MAP, a new additive solution].

The clinical safety and efficacy of transfusion of red cell concentrates stored in MAP solution (MAP-CRC) containing mannitol, adenine, glucose, phosphate and citrate, into 39 anemic patients were evaluated. In 23 patients, infusion of MAP-CRC was alternated with infusion of ordinary CRC as a control. The MAP-CRC and CRC used in this study were stored at 4 degrees C for an average of 38.2 +/- 2.6 days (n = 52) and 18.1 +/- 2.2 days (n = 26), respectively. Red cell recovery was 77.5% for MAP-CRC and 82.5% for CRC, based on calculation of the increase in hemoglobin level one day after transfusion. There were no differences between patients transfused with MAP-CRC and those transfused with CRC in clinical findings or biochemical data. No major side-effects other than pyrexia associated with the underlying infections were seen in patients transfused with MAP-CRC. MAP-CRC stored up to 42 days is apparently as safe and effective as stored CRC. This new additive solution may therefore be useful for the future expansion of the indications for autologous blood transfusion by facilitating the collection and storage of more blood in the liquid state for a longer period, and may also be useful in obtaining more plasma from whole blood as source plasma.

Adenine↗
PubMed1991

Identity determinants of E. coli tryptophan tRNA.

The first base pair of the acceptor stem A1-U72 and the discriminator base G73, as well as the anticodon nucleotides, characterize the tryptophan tRNA in E. coli. To determine the contribution of these nucleotides to the tryptophan acceptor activity, various transcripts of E. coli tryptophan tRNA mutants were constructed. Substitutions of the discriminator base G73, which is conserved within prokaryotic tryptophan tRNAs, impaired aminoacylation with tryptophan. Substitutions of other purine-pyrimidine pairs for A1-U72 revealed that only U72 weakly contributed to recognition by tryptophanyl-tRNA synthetase. The E. coli aspartic acid tRNA transcript introducing the tryptophan anticodon CCA showed almost the same tryptophan charging activity as the tryptophan tRNA transcript possessing a G1-C72 base pair. Only a low activity was detected in the mutant tryptophan tRNA transcript possessing a set of G1-C72 and A73, which is observed in eukaryotic tryptophan tRNAs. These results indicate that the anticodon and G73 are major identity determinants of tryptophan tRNA in E. coli, whereas the A1-U72 base pair is only a weak recognition element.

Anticodon↗
PubMed1991

Left atrial afterload mismatch in hypertrophic cardiomyopathy.

To investigate left atrial (LA) booster pump function in hypertrophic cardiomyopathy (HC), LA and left ventricular pressure-volume loops were estimated in 5 control subjects, 6 patients with essential hypertension and 11 patients with HC. Investigation of LA preload revealed that LA pressure and volume immediately before LA contraction were both increased in patients with hypertension (10 +/- 5 mm Hg, 71 +/- 19 ml/m2) compared with control subjects (7 +/- 1 mm Hg, 59 +/- 6 ml/m2), and even more increased in patients with HC (16 +/- 7 mm Hg, 81 +/- 25 ml/m2). Investigation of LA afterload revealed that the left ventricular chamber stiffness constant was higher in patients with hypertension (0.035 +/- 0.015) than in control subjects (0.028 +/- 0.009), and even more increased in patients with HC (0.056 +/- 0.017). LA stroke work index was higher in patients with hypertension (116 +/- 34 mm Hg.ml) and HC (115 +/- 19 mm Hg.ml) than in control subjects (87 +/- 23 mm Hg.ml). Investigation of LA ejection revealed that LA stroke index was higher in patients with hypertension (24 +/- 5 ml/m2) than in control subjects (18 +/- 4 ml/m2) and patients with HC (18 +/- 2 ml/m2), and LA ejection fraction was lower in patients with HC (23 +/- 6%) than in control subjects (32 +/- 7%) and patients with hypertension (34 +/- 8%). In patients with HC, LA function curve showed a shift to the lower right, and LA stroke index was inversely correlated (r = -0.76) with LA afterload. This study suggests that LA booster pump failure due to LA afterload mismatch exists in HC.

Adult↗
PubMed1991

Identity determinants of E. coli tRNA(Val).

In order to study the identity elements of valine tRNA, various transcripts of E. coli valine tRNA mutants were constructed. Both mutations at the second letter A35 of the anticodon and at the discriminator base A73 seriously damaged valine charging activity. Mutations at either the G3-C70 or U4-A69 base pairs in the acceptor stem also affected the activity. Only one nucleotide substitution of the second letter G35 of the anticodon with A35 brought an 18% valine charging activity into alanine tRNA, which acquired an almost full charging activity with valine by introducing an additional change at those two base pairs in the acceptor stem. These results indicate that the second letter A35 of the anticodon, discriminator base and acceptor stem are involved in recognition by valyl-tRNA synthetase.

Base Composition↗
PubMed1991

Nucleosomes are positioned with base pair precision adjacent to the alpha 2 operator in Saccharomyces cerevisiae.

Analysis of the chromatin structure of minichromosomes containing the binding site for the yeast alpha 2 repressor protein by indirect end-labeling has previously indicated that nucleosomes are stably positioned over sequences adjacent to the alpha 2 operator in the presence of the repressor. Development of a primer extension assay for nucleosome position now allows a more detailed examination of the location of these nucleosomes relative to the operator sequence, and indicates that nucleosomes are precisely and stably positioned both translationally and rotationally over sequences adjoining the operator. In addition, this assay enables analysis of the chromatin structure of single copy, genomic sequences. Chromatin structures determined for two genes regulated by alpha 2, STE6 and BAR1, are consistent with nucleosomes precisely positioned downstream of the operator sequence, incorporating promoter elements, in alpha cells but not in a-cells. The location of these nucleosomes relative to the operator sequence is highly analogous to that observed in the minichromosome. The stability of the nucleosomes adjacent to the operator together with the precision of their location suggests that they may play a role in repression of a specific gene expression by alpha 2. Further, the primer extension assay allows a comparison of the structure of these positioned nucleosomes formed in vivo to that previously described for core particles reconstituted in vitro.

Base Composition↗
PubMed1991

Structural and composition studies on the mineral of newly formed dental enamel: a chemical, x-ray diffraction, and 31P and proton nuclear magnetic resonance study.

The present report describes a study of the development and maturation of the mineral component of dental enamel. We prepared porcine enamel of different stages of maturation, from the very immature enamel of unerupted teeth, with a mineral content of 45%, to fully mature enamel, with a mineral content of approximately 99%. We fractionated the less mature enamel by density centrifugation and examined the enamel density fractions and unfractionated enamel by a variety of chemical and physical techniques, including conventional and radial distribution function x-ray diffraction analysis, conventional and Fourier transform infrared spectroscopy, 31P and 1H nuclear magnetic resonance spectroscopy, and chemical analysis. The three most immature preparations, from unerupted teeth, had mineral contents of 45, 67, and 91 and Ca/P molar ratios of 1.41, 1.44, and 1.47. Density distribution histograms of the three fractions show that the early maturation of dental enamel mineral is accompanied by an increase in tissue density, reflecting the increase in mineral content. The density distribution in each sample is relatively narrow, indicating that the maturation process occurs at a fairly homogeneous rate, with all enamel in an anatomically defined zone mineralizing to about the same extent. X-ray diffraction studies indicate that even the least mature, least mineralized of these immature samples is considerably more crystalline than the most mature bone mineral studied and that crystalline perfection of the enamel crystals crystals increases further with maturation. Both the a and c axes of the mineral unit cell expand significantly during early stages of maturation. Solid-state 31P nuclear magnetic resonance spectroscopy studies indicate that dental enamel contains a DCPD-like HPO4 component in an apatitic lattice, similar to the component previously observed in bone and some synthetic calcium phosphates. The proportion of this DCPD-like component decreases with maturation but is readily detectable even in fully mature enamel. The infrared spectroscopic studies indicate that the 3570 cm-1 band ascribed to the OH- group of the hydroxyapatite crystals is absent in the least mature enamel but can be detected and becomes progressively stronger as the enamel becomes more mature. The increase in the content of the OH- groups of the apatite crystals is concomitant with the observed increase in unit cell parameters. Similar studies on very young and very old mature bone of four different species failed to detect the presence of OH- groups.

Aging↗
PubMed1991

Altered steady-state levels of mRNA coding for extracellular matrices in renal tissues of ddY mice, an animal model for IgA nephropathy.

Correlations between the steady-state mRNA levels of extracellular matrices using specific cDNA probes for the alpha 1 chain of type IV collagen (alpha 1 (IV) chain); laminin A, B1, and B2 chains; and heparan sulfate proteoglycan (HSPG); and glomerular injuries in ddY mice were evaluated. Eight-, sixteen- and forty-week-old ddY mice were used in this study. ICR mice of the same age served as control. Extracted total RNA of pooled kidneys was fixed on a filter and then hybridized with the cDNA probes. Renal cryostat sections were incubated with rabbit anti-mouse type IV collagen, laminin, and HSPG antisera and then stained with FITC-labeled goat anti-rabbit IgG antiserum. The sections were also stained with FITC-labeled goat anti-mouse IgA, IgM, IgG, and C3 antisera. In light microscopy, the average number of glomerular cells was calculated at each age. Increased expression of extracellular matrices genes for the alpha 1(IV) chain; laminin A, B1, and B2 chains; and HSPG was found in renal tissues of ddY mice. Staining of type IV collagen, laminin, and HSPG was observed in renal tissues of ddY mice at each age. Increased proteinuria in 40-week-old ddY mice might be related to the decrease in glomerular basement membrane HSPG which acts as the anionic sites in such areas. Marked proliferation and or expansion of glomerular cells and mesangial matrices were observed in 40 week-old-ddY mice. The intensity of IgA and C3 deposits in the glomeruli was parallel to the levels of mRNA for such components.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗