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Biomedical subjects

T Tamura

Publications and source records attributed to T Tamura.

At least 973 records · Page 54Linked to original sources
PubMed1989

Doppler color flow mapping of simulated in vitro regurgitant jets: evaluation of the effects of orifice size and hemodynamic variables.

The spatial distribution of simulated regurgitant jets imaged by Doppler color flow mapping was evaluated under constant flow and pulsatile flow conditions. Jets were simulated through latex tubings of 3.2, 4.8, 6.35 and 7.9 mm by varying flow rates from 137 to 1,260 cc/min. Color jet area was linearly related to flow rate at each orifice (r = 0.96, SEE = 3.4; r = 0.99, SEE = 1.6; r = 0.97, SEE = 2.3; r = 0.97, SEE = 3.2, respectively), but significantly higher flow rates were required to maintain the same maximal spatial distribution of the jet at the larger regurgitant orifices. Constant flow jets were also simulated through needle orifices of 0.2, 0.5 and 1 mm, with a known total volume (5 cc) injected at varying flow rates and with differing absolute volumes injected at the same flow rate (0.2, 1.0 and 2.0 cc/s, respectively). Again, maximal color jet area was linearly related to flow rate at each orifice (r = 0.97, SEE = 2.3; r = 0.97, SEE = 2.4; r = 0.92, SEE = 3.9, respectively), but was not related to the absolute volume of regurgitation. Color encoding of regurgitant jets on Doppler color flow maps was demonstrated to be highly dependent on velocity and, hence, driving pressure, such that color encoding was obtained from a constant flow jet injected at a velocity of 4 m/s through an orifice of 0.04 mm diameter with flow rates as low as 0.008 cc/s. Mitral regurgitant jets were also simulated in a physiologic in vitro pulsatile flow model through three prosthetic valves with known regurgitant orifice sizes (0.2, 0.6 and 2.0 mm2). For each regurgitant orifice size, color jet area at each was linearly related to a regurgitant pressure drop (r = 0.98, SEE = 0.15; r = 0.97, SEE = 0.20; r = 0.97, SEE = 0.23, respectively), regurgitant stroke volume (r = 0.77, SEE = 0.55; r = 0.94, SEE = 0.30; r = 0.91, SEE = 0.41, respectively) and peak regurgitant flow rate (r = 0.98, SEE = 0.16; r = 0.97, SEE = 0.21; r = 0.93, SEE = 0.37, respectively), but the spatial distribution of the regurgitant jets was most highly dependent on the regurgitant pressure drop. Jet kinetic energy calculated from the summation of the individual pixel intensities integrated over the jet area was closely related to driving pressure (r = 0.84), but integration of the power mode area times pixel intensities provided the best estimation of regurgitant stroke volume (r = 0.80).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Factors influencing the structure and shape of stenotic and regurgitant jets: an in vitro investigation using Doppler color flow mapping and optical flow visualization.

To evaluate factors influencing the structure and shape of stenotic and regurgitant jets, Doppler color flow mapping and optical flow visualization studies were performed with use of a syringe model with a constant rate of ejection to simulate jets of valvular regurgitation and a pulsatile flow model of the right heart chambers to simulate jets of mild, moderate and severe valvular pulmonary stenosis. Ink-(0 to 40%) glycerol-water jets (viscosity 1 to 3.5 centiPoise) were produced by injecting the fluid at a constant rate into a 10 gallon rectangular reservoir of the same still fluid through 1.4 and 3.4 mm needles. The Doppler color flow scanners imaged the laminar jet length within 3 mm of actual jet length (2 to 6 cm) and the jet width within 2 to 3 mm of the actual jet width. Jet flows with Reynolds numbers ranging from 230 to 1,200 injected into still fluid yielded jet length/width ratios that decreased with increasing Reynolds numbers and leveled off to a length/width ratio of 5-6:1 at a Reynolds number near 600. When the fluid reservoir was swirled to better mimic the effect of flow entering the same cardiac chamber from a second source, the jets showed diminution of the jet length/width ratio and a clearly defined zone of turbulence. Studies of the pulsatile flow model were performed at cardiac outputs of 1 to 6 liters/min for the normal and each stenotic valve. Mild stenosis had an orifice area of 2.8 cm2, moderate stenosis an area of 1.0 cm2 and severe stenosis an area of 0.5 cm2. Laminar jet length represented the length of the total jet, which had a symmetric width and was measured from the valve opening to a region where the jet exhibited a spray effect. Laminar jet lengths (0.2 to 1.1 cm) were imaged by Doppler color flow mapping and optical visualization only in the moderate and severely stenotic valves and only at flows less than or equal to 3 liters/min (mean Reynolds numbers less than or equal to 3,470). Beyond this flow rate the jets exhibited a spray effect. Laminar jet length/width ratio approached unity with an increased amount of valvular stenosis and higher flow volumes (cardiac output). Proximal aliasing was present in each valve studied. the length of aliasing (0 to 3.2 cm) proximal to the valve was longer with increased flow rates and increased amounts of stenosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Flow Velocity↗
PubMed1989

Folic acid safety and toxicity: a brief review.

Oral folic acid (pteroylglutamic acid) is generally regarded as not toxic for normal humans but it may cause neurological injury when given to patients with undiagnosed pernicious anemia. The vitamin should be given with caution to drug-treated epileptic patients because seizure control may be affected. Some studies suggest that folic acid supplements interfere with intestinal zinc absorption in humans and animals but others do not confirm such an effect. The weight of current evidence favors the view that daily supplements of 5-15 mg folic acid do not have significant adverse effects on Zn nutriture in healthy nonpregnant subjects. Because antifolate medications are now being used to treat a wide range of malignant and nonmalignant disorders, further investigation is needed concerning folate metabolism and the safety of supplements in patients with these disorders.

Anemia, Pernicious↗
PubMed1989

Inhibitory effect of glycosides like saponin from soybean on the infectivity of HIV in vitro.

Soybean saponins isolated from soybean seeds were investigated for their antiviral activity on HIV in vitro, using an HTLV-I-carrying cell line, MT-4. Saponin B1 completely inhibited HIV-induced cytopathic effects and virus-specific antigen expression 6 days after infection at concentrations greater than 0.5 mg/ml. Saponin B2 also inhibited HIV infection, although less potently. Both saponin B1 and B2 had no direct effect on the reverse transcriptase activity of HIV. Saponin B1 also inhibited HIV-induced cell fusion in the MOLT-4 cell system. The results of this study suggest that soybean saponins, especially saponin B1, have inhibitory activity against HIV infection.

Antiviral Agents↗
PubMed1989

Serial measurement of sister chromatid exchanges in the peripheral lymphocytes of patients with lung cancer receiving chemotherapy in relation to bone marrow toxicity.

The frequencies of sister chromatid exchanges (SCE) in the peripheral lymphocytes of patients with lung cancer before and after initial chemotherapy were serially measured and the correlation between SCE frequencies and bone marrow toxicity was evaluated. The addition of mitomycin C to vindesine plus cisplatin increased SCE frequencies significantly in patients with non-small cell lung cancer. A significant increase in frequencies of SCE was observed in patients treated with cyclophosphamide plus adriamycin plus vincristine as compared with those treated with cisplatin plus etoposide in small cell lung cancer. A significant inverse correlation was observed between SCE frequencies in the peripheral lymphocytes 7 days after treatment (x) and the nadir value/pretreatment value of platelets (y)(r = -0.685, P = 0.0007, y = 0.842-0.022x). The relation between SCE frequency and leukopenia showed the same trend as thrombocytopenia, but the correlation was not statistically significant (r = -0.444, P = 0.057). SCE assay may have potential clinical use for the prediction of chemotherapy-induced thrombocytopenia.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1989

Inhibition of colony formation of drug-resistant human tumor cell lines by combinations of interleukin-2-activated killer cells and antitumor drugs.

The cytotoxicity of interleukin-2-activated killer (LAK) cells with or without anticancer drugs against cell lines with acquired drug resistance was evaluated in vitro by colony assay. Human non-small cell lung cancer cell lines, PC-9 and PC-14, human leukemia cell line, K-562, and their sublines resistant to cisplatin (CDDP), PC-9/CDDP and PC-14/CDDP, and to adriamycin (ADM), K-562/ADM, were used as target cells. PC-9/CDDP demonstrated a marked increase in susceptibility to killing by both peripheral blood lymphocytes (PBL) and LAK cells, as compared to the parental cell line, PC-9. The cytotoxicity of PBL and LAK cells against PC-14/CDDP and K-562/ADM was similar to that against their parental cell lines. Moreover, the combination of LAK and CDDP had a synergistic effect on PC-14 and PC-14/CDDP.

Adenocarcinoma↗
PubMed1989

[A comparative study between cefodizime (CDZM) and cefotaxime (CTX) in respiratory tract infections].

The clinical efficacy and safety of Cefodizime (CDZM), a new cephem antibiotic, was objectively compared with that of Cefotaxime (CTX) in patients with respiratory infections under a well-controlled comparative study. Patients were administered CDZM or CTX by drip infusion b.i.d. for 14 days in principle at a daily dose of two grams. The parameters assessed were clinical efficacy, safety and clinical usefulness. The following results were obtained: 1. On the basis of committee judgement the clinical efficacy rate was 78.1% (125/160) for the CDZM group, 82.7% (124/150) for the CTX group, and no significant difference was observed between the two drug groups. On the other hand, on the basis of judgement by physicians in charge, the clinical efficacy rate was 83.1% (133/160) for the CDZM group, 83.9% (125/149) for the CTX group, and no significant difference was observed between the two groups. 2. The corresponding figures for patients with pneumonia and pulmonary suppuration were 82.4% (70/85) for the CDZM group, 79.7% (59/74) for the CTX group and no significant difference was observed according to the committee judgement. The judgement by physicians in charge also revealed 83.5% (71/85) for the CDZM group and 82.2% (60/73) for the CTX group. No significant difference was noted between the two groups. While, the committee judgement for the clinical efficacy in patients with chronic respiratory tract infections showed 73.3% (55/75) for the CDZM group, 85.5% (65/76) for the CTX group, and no significant difference was observed between the two drug groups. The corresponding figures were 82.7% (62/75) for the CDZM group, 85.5% (65/76) for the CTX group, and no significant difference was observed between the two drug groups on the judgement by physicians in charge. Furthermore, the clinical efficacy of both drugs on chronic respiratory tract infections was assessed according to "Criteria for Evaluation of Clinical Efficacy of Chemotherapeutics on Chronic Respiratory Tract Infection". It was 76.8% (53/69) for the CDZM group, 76.3% (58/76) for the CTX group, and no significant difference was observed between the two groups. 3. The bacteriological eradication rate of causative pathogens was 92.4% out of 66 patients treated with CDZM and 95.5% out of 67 patients treated with CTX in whom judgement was possible. No significant difference was observed between the two drug groups. 4. The adverse reactions occurred in 4 (2.2%) patients for the CDZM group and 8 (4.5%) patients for the CTX group respectively, with no significant inter-group difference in frequency of these reactions for all cases.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Bacterial Agents↗
PubMed1989

Endotoxin-induced serum factor that stimulates gamma interferon production.

Serum from Mycobacterium bovis BCG-infected mice that had been challenged with lipopolysaccharide (LPS) exhibited a marked ability to induce gamma interferon (IFN-gamma) in cultures of spleen cells of normal mice in the presence of interleukin-2 (IL-2). The inducing activity became detectable in the circulatory system about 90 min after LPS challenge, disappeared at around 5 h, and was observable upon 640x dilution of the serum. Addition of monoclonal anti-IL-2 receptor antibody to the culture inhibited the induction by the serum. The activity induced high levels of IFN-gamma even in nylon wool-nonadherent cells, while concanavalin A failed to do so. Serum from uninfected mice challenged with LPS contained no such activity. The molecular weight of the active substance, estimated by gel filtration, was about 70,000. There were pronounced differences among mouse strains in the activities of the sera prepared, which paralleled the amounts of IFN-gamma produced in vivo. However, the levels of IFN-gamma produced in whole spleen cells and in nylon wool-nonadherent cells from mice of various strains were the same when stimulated with competent serum. These results indicate the existence of an unidentified factor that induces IFN-gamma in cooperation with IL-2 in macrophage-depleted splenocytes. They also suggest that IFN-gamma production in vivo is not genetically controlled at the lymphocyte level but, rather, at the level of synthesis of the unknown factor.

Animals↗
PubMed1989

Tissue-specific in vitro transcription from the mouse myelin basic protein promoter.

The mouse myelin basic protein promoter was transcribed in brain nuclear extracts. The distal promoter region from -253 to -54 directed preferential transcription in brain extracts, whereas the same region repressed transcription activity in liver extracts. Stimulation of transcription was observed when the distal region was located only in a native orientation. The proximal region downstream from -53 alone still directed preferential transcription. It is suggested that cooperative function by the two promoter regions may be required for higher specificity.

Animals↗
PubMed1989

Immunoelectron microscopic localization of fibrin-related antigen in human glomerular diseases.

The distribution of fibrin-related antigen (FRA) in glomeruli was examined by immunoelectron microscopy in 9 patients with idiopathic membranous nephropathy (MN), 8 patients with minimal-change nephrotic syndrome, and 10 patients with IgA nephropathy (IgA-N), using antisera against human gamma--chain, alpha-chain, mu-chain, and fibrinogen. Electron-dense reaction products of FRA were observed in the endothelium, subendothelium, and/or in electron-dense deposits (EDD). Among the three glomerular diseases, the amount of electron-dense reaction products of FRA in the endothelium was highest in MN. This suggests that coagulation occurs on the endothelium in MN. Although the mesangial EDD of IgA-N were intensely stained with reaction products of FRA, the staining was weak in the subepithelial EDD of MN. This suggests that FRA hardly penetrates into the subepithelial EDD in MN.

Antigens↗
PubMed1989

Ultrastructural distribution of von Willebrand factor in human glomerular diseases.

The distribution of the von Willebrand factor (vWF) as the factor-VIII-related antigen in glomeruli was examined by immunoelectron microscopy in 10 patients with idiopathic membranous nephropathy (MN), 8 patients with minimal-change nephrotic syndrome (MCNS), and 11 patients with IgA nephropathy (IgA-N). Electron-dense reaction products of vWF were observed in the endothelium and mesangium in all specimens examined. However, they were not detected in subepithelial electron-dense deposits of MN. The amount of electron-dense reaction products of vWF in the endothelium was significantly higher in MN than that in MCNS or IgA-N. This finding suggests that the glomerular endothelium in MN is the site of the local activation of coagulation and platelet aggregation system in glomerular capillary wall lesions.

Glomerulonephritis, IGA↗
PubMed1989

Effect of hydergine in hyperprolactinemia.

The PRL-inhibiting and ovulation-inducing effects of hydergine were studied in 18 patients with hyperprolactinemic ovulatory disturbances. The women were divided into 2 groups of 9 each. Those in group A had basal serum PRL levels higher than 100 micrograms/L, and those in group B had basal serum PRL levels lower than 100 micrograms/L. Serum PRL levels in both groups were determined before and hourly for 8 h after a single oral dose of either 2 mg hydergine or placebo. Hydergine induced a significant (P less than 0.01) decrease in the serum PRL level, compared with placebo, in both groups. The fall in mean serum PRL in group A was significant (P less than 0.05) 300 min after hydergine administration, and the concentration remained low at 480 min, at 45.5% of the mean baseline value. However, the serum PRL concentration did not reach the normal PRL range in any group A patient. Chronic treatment with this drug (2 mg, 3 times daily, for 4-12 weeks) in 5 patients from group A normalized the serum PRL concentration in only 1 patient and did not induce ovulation in any patient. In group B, also, hydergine administration significantly (P less than 0.01) reduced the mean serum PRL concentration within 240 min, and it declined further to within the normal range. The mean maximal reduction was to 56.4% of the baseline value at 360 min. All of the group B women received chronic treatment (2 mg, 3 times daily, for 4-104 weeks); repeated ovulation was induced in 7 (78%). Seven pregnancies ensued in 6 of the women in whom ovulation had been induced, and 4 normal infants were delivered. There were no side-effects, such as nausea and vomiting, during these trials. These data indicate that hydergine has PRL inhibitory activity and is useful in the treatment of hyperprolactinemic anovulatory patients whose basal serum PRL concentrations are below 100 micrograms/L.

Adolescent↗
PubMed1989

Cranial symptoms after cervical injury. Aetiology and treatment of the Barré-Liéou syndrome.

Neck injury of the whiplash type may lead to the cranial symptoms of the Barré-Lieou syndrome. Forty patients with this syndrome and 40 without it were investigated by a variety of imaging techniques. There was a clear correlation between root sleeve defects at C3/4 shown by special oblique myelographic views and cranial symptoms. Good results were obtained by anterior cervical discectomy and fusion at C3/4 in 21 cases. It is suggested that the syndrome may result from irritation of the sympathetic nervous supply at this level.

Adolescent↗