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Biomedical subjects

N Kamata

Publications and source records attributed to N Kamata.

At least 55 records · Page 3Linked to original sources
PubMed1991

[Differential diagnosis between recurrence of brain tumor and radiation necrosis by 201Tl SPECT].

In order to differentiate recurrence of brain tumor from radiation necrosis, we performed 201Tl brain SPECT in 16 post-operative patients. Five of them had residual anaplastic astrocytoma. Final diagnosis of the other 11 patients was recurrent astrocytoma (n = 6), cerebral radiation necrosis (n = 5), based on re-operation (n = 9) and more than one year follow-up finding (n = 2). Early and delayed images were obtained at 10-15 min. and 4 hrs. after i.v. injection of 111 MBq of 201Tl chloride. Counts ratio of a lesion to the normal brain (L/N) was calculated by creating rectangular ROI over each area. All of the patients with recurrent or residual tumor showed L/N ratios of more than 2.5 on the early images (mean 4.70 +/- 2.65). On the other hand, L/N ratios on the early images were less than 2.5 in patients with radiation necrosis (mean 2.05 +/- 0.25, p less than 0.001). In conclusion, a quantitative assessment using 201Tl brain SPECT may be useful in differentiating recurrence of brain tumor from radiation necrosis.

Adult↗
PubMed1991

[67Ga citrate imaging in AIDS-related Pneumocystis carinii pneumonia in Japan].

Six AIDS patients with Pneumocystis carinii pneumonia (PCP) underwent 67Ga scan as part of their evaluation. Only one patient of them showed the characteristic 67Ga distribution pattern for PCP, that is, diffuse, increased, bilateral lung activity greater than liver activity. Two patients who were receiving therapy for PCP and one patient with recurrent PCP showed focal or uneven 67Ga lung uptake. In the four patients, the scan showed more extensive lesion than the chest radiograph. The other two patients who died 2 months later of cellular immunodeficiency showed no or very slight lung uptake of 67Ga. In summary, 67Ga scanning is useful diagnostic procedure in evaluation of PCP in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Antisense mapping of the c-fos promoter: role of the serum response element.

Using an antisense RNA approach to eliminate endogenous expression of the c-fos protein, we have verified by nuclear run-on and transient expression assays that the Fos protein is a negative regulator of its own transcription in vivo. The negative autoregulation of the c-fos promoter by Fos was further confirmed by overexpression of an antisense-resistant c-fos expressing vector. Antisense mapping of the c-fos promoter demonstrated that the serum responsive element (SRE) represents the major site for c-fos suppression only during the first hour, but that additional adjacent DNA sequences are required for suppression at later times. We propose that antisense inhibition of transcriptional repressors provides a useful method for analyzing the significance and mechanism of transcriptional repression in vivo.

3T3 Cells↗
PubMed1991

Myristylation alters DNA-binding activity and transactivation of FBR (gag-fos) protein.

FBR murine sarcoma virus (gag-fos) protein, a virally transduced Fos protein, exhibits decreased gene transactivation in comparison with the cellular Fos protein. Biochemical analysis suggests that myristylation of the virally encoded N-terminal gag region results in decreased DNA binding and transcriptional activation without affecting heterodimerization with Jun protein. These findings demonstrate that protein myristylation can modulate gene regulation by a DNA-binding protein.

Amino Acid Sequence↗
PubMed1991

Clinical significance of abnormal Q wave disappearance in acute transmural myocardial infarction.

The clinical features of acute myocardial infarction patients in whom abnormal Q wave disappeared were analyzed. Of 201 patients, 40 (20%) (Group A) showed disappearance of Q wave in serial electrocardiograms. Regional ejection fraction of the infarcted portion improved significantly (from 24 +/- 2 to 34 +/- 4%, p less than 0.001) during chronic phase in Group A, but no such improvement was present in Group B patients who showed no change in the Q wave. Global ejection fraction was greater and percent akinetic segment was smaller in Group A than in Group B at chronic phase. Coronary occlusion occurred more often at segment 7 in Group A; in Group B, occlusion occurred more frequently upstream at segment 6, suggesting Group A had a smaller area of risk. Spontaneous recanalization was more often (57%) and complete occlusion was less frequent in Group A. These indicate that Group A is characterized by a smaller area of risk, smaller infarct size, earlier reperfusion, and greater improvement in wall motion. Twenty-eight patients (70%) of Group A lost Q wave within one month and 12 patients (30%), after 3 months or more. Electrical stunning of the myocardium may be a possible mechanism for the early disappearance of Q waves, and anatomical healing for the late disappearance of Q waves.

Electrocardiography↗
PubMed1991

Effects of residual coronary stenosis on myocardial salvage after reperfusion in dogs.

In order to study the effects of residual stenosis on myocardial salvage, we created 99% coronary stenosis with or without contrast washout delay at reperfusion in six groups of dogs. In Group A (n = 8), the artery was occluded for 1h before being fully reperfused. In Group B (n = 9), the artery was occluded for 1h, then subjected to 6h of 99% stenosis without contrast washout delay. In Group C (n = 8), the artery was occluded for 1h, followed by 1 week of 99% stenosis without contrast washout delay. In Group D (n = 10), again the artery was occluded for 1h, then subjected to 6h of 99% stenosis with contrast washout delay. In Group E (n = 8), the artery was occluded for 7h, then fully reperfused for 1 week. Finally, in Group F (n = 8), the occlusion lasted for a full week. All dogs were sacrificed 1 week after occlusion. In Group A, myocardial creatine phosphokinase activity (CK) in the inner layer was 43.8 +/- 12.5% that of non-infarcted myocardium. Myocardial CK in Group B (46.5 +/- 7.4%) was little different but in Group C it dropped to 26.6 +/- 8.4%, suggesting that 99% residual stenosis is not deleterious if it is continued for 6h or less but that it will result in considerable depletion of myocardial CK, it is is sustained for 1 week. In Group D, myocardial CK dropped markedly to 11.3 +/- 3.7%, little different from that for either Group E (13.3 +/- 2.6%) or Group F (9.3 +/- 3.3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The importance of good endocardial reflow immediately after reperfusion for myocardial salvage in dogs.

We studied the importance of reflow after reperfusion for myocardial salvage. In 19 open-chest dogs, the left anterior descending coronary artery was occluded for 3h and then reperfused. Non-radioactive colored microspheres were injected into the left atrium to measure regional myocardial blood flow (RMBF). Immediately after occlusion, RMBF was reduced to 23 +/- 2% (of control) in the inner layer and 32 +/- 2% in the outer layer. Five minutes after reperfusion, RMBF was increased to 170 +/- 20% and 156 +/- 11% of control in the inner and outer layers, respectively. One week later, RMBF in the inner layer was reduced to 63 +/- 4% but it was not reduced (100 +/- 6%) in the outer layer. There was a roughly positive correlation between the inner/outer flow ratio measured 5 min after reperfusion and myocardial creatine kinase activity. Myocardial necrosis determined by triphenyl tetrazolium chloride stain varied inversely with the inner/outer flow ratio. These results indicate that good reflow in the inner layer 5 min after reperfusion is a favorable indicator for myocardial salvage.

Animals↗
PubMed1991

[Clinical characteristics of precordial ST-segment depression in acute inferior myocardial infarction].

Assessments of the significance of precordial ST segment depression in acute inferior myocardial infarction (AIMI) have yielded conflicting results. Among 92 AIMI patients admitted within 6 hrs after the onset, 65 showed ST depression, and the remaining 27 showed no ST depression. These depressions were present in all of V1-4 (right type; 17), V2-5 (middle type; 10), V3-6 (left type; 13) and V1-6 (broad type; 25). The clinical severity was Forrester subset I in the majority (89%) of patients without ST change, while complications were prevalent in patients with ST depression, especially in the right type (44% were Forrester subset II-IV). Peak CK was 2,150 +/- 399 U/L in patients without ST depression, but it was elevated to 3,172 +/- 811 in patients with ST depression, especially in the right type (4,506 +/- 499). Wall motion evaluated by echocardiography and QRS scores on ECG also revealed greater abnormality in patients with ST change. The initial right coronary angiogram on admission revealed complete occlusion in 76% of these patients with ST depression of whom all of the right type had completely occluded artery. Abnormal motion of the anterior wall, which suggests remote ischemia associated with AIMI was proved neither by left ventriculography nor echocardiography. Hospital mortality in patients with ST depression (9.2%) was as twice as high as that in those without ST depression (4.6%). We concluded that ST depression in patients with acute inferior infarction may not be indicative of remote ischemia but manifests as a mirror image of a large infarction with a complicated clinical course.

Adult↗
PubMed1990

Growth of the malignant and nonmalignant human squamous cells in a protein-free defined medium.

A novel protein-free synthetic medium has been developed for the culture of human squamous cell carcinoma cells. This medium, designated PF86-1, supports the serial subcultivation of six out of nine human squamous cell carcinoma cell lines in a protein-free, chemically defined condition without the adapting culture from serum-containing conditions. These cell lines growing in PF86-1 exhibited nearly equal potency to grow in massive culture without noticeable changes in morphology but presented a significantly decreased level of colony forming efficiency when compared with the cells cultured in serum-containing media, suggesting the implication of some autocrine mechanism. Interestingly, this medium supported the growth of normal human squamous cells of oral mucosa and skin for more than 2 mo. in the primary explant culture in spite of high levels of calcium ion concentration, where the overgrowth of fibroblasts as contaminant was not observed. These results suggest that PF86-1 supports the growth of cells derived from epidermal tissues selectively and provides the same defined condition for growth of malignant and nonmalignant human squamous cells. It seems, therefore, that PF86-1 allows investigations on the products of squamous cell carcinoma cells or on the differences of growth mechanisms between normal and neoplastic human squamous cells.

Carcinoma, Squamous Cell↗
PubMed1990

[Incidence and clinical significance of the esophageal branches originating from the bronchial artery].

The authors investigated the incidence and extent of angiographic visualization of the esophageal branches originating from the bronchial arteries. Approximately 20% of 371 patients showed considerable blood flow to the esophagus. The left bronchial artery more often gives rise to the esophageal branches. Esophageal complications have been experienced in 8 cases following bronchial artery infusion of Mitomycin C for pulmonary carcinoma. Complications tend to occur in cases showing marked opacification of the esophageal veins or in those which a lesion locates in the peripheral portion of the lung. It is imperative to pay attention to esophageal branches of the bronchial artery in interventional angiography.

Bronchial Arteries↗
PubMed1990

[Usefulness of ventilation and perfusion scans in patients with collagen-vascular diseases].

We studied 32 patients with collagen-vascular diseases with Xe-133 ventilation scans (V) and Tc-99m MAA perfusion scans (Q). Five patients underwent sequential studies at intervals of more than 3 months. Mean transit time (MTT) was calculated from the Xe-133 wash-out curve. V, Q images and MTT were compared with chest X-ray films and the values of %DLco. Of 32 patients, 17 had no abnormal finding on the chest X-ray films. Of the 17 patients, however, V and/or Q abnormalities were found in 10 (59%), 14 patients (82%), respectively. Every patient with abnormal findings on the chest X-ray film showed both V and Q abnormalities. Overall, Q abnormality was more frequent and severer than V one. Of the 5 patients with the sequential studies, 3 showed prolongation of MTT in concordance with deterioration of pulmonary fibrosis. V and Q abnormalities were not necessarily relevant to %DLco. In conclusion, ventilation and perfusion studies are useful in assessing the regional pulmonary function in patients with collagen-vascular diseases.

Adult↗
PubMed1989

[Clinical investigation of the branching formation of the bronchial arteries in the Japanese].

It is imperative to be familiar with anatomical variation in the branching formation of the bronchial artery for radiologists attempting an interventional angiography to the pulmonary diseases such as hemoptysis or pulmonary carcinoma. The anatomy of the bronchial arteries reported by Cauldwell et al. is the most frequently quoted literature in the world as well as in Japan. However, we had noticed that some discrepancies exist between our clinical experience and those in Cauldwell's report regarding anatomical variation of the bronchial arteries. Then, we reviewed the bronchial arteriograms in 640 patients. We included 412 patients in investigation, in which it was possible to identify the branches supplying all pulmonary lobes. In 50 out of 640 patients, catheterization of the branches supplying the lesion was failed. Branching formation of the bronchial arteries is extremely variable and complicated by presence of the accessory bronchial arteries and anastomosing branches from the systemic arteries, which may be enlarged in various pathological conditions. Our results showed that the most common branching type was single artery on each side (50.0%), followed by common trunk (14.1%). The incidence of single on the right and dual on the left, most common in Cauldwell's series, was only 12.9%. Kasai and Chiba also pointed out these differences in their detail report investigating 100 cadavers. These discrepancies between the data may be due to differences of methodology or due to differences between the races. The authors feel that Cauldwell's data should not be referred to the anatomical variation of the bronchial artery in Japanese.

Asian People↗
PubMed1989

Reduction of G1 phase duration and enhancement of c-myc gene expression in HeLa cells at hypergravity.

We have found that hypergravity stimulates the proliferation of HeLa cells through reduction of the G1 phase duration, concomitant with enhancement of c-myc gene expression. HeLa cells were grown in monolayer in culture flasks that were centrifuged to generate a constant 18, 35 or 70 g at 37 degrees C for up to 4 days. The cell proliferation was enhanced at 18, 35 and 70 g, most notably at 35 g. Cell cycle analyses with [3H]thymidine (TdR)-colcemid treatment showed that the cell generation time in the 35 g culture was reduced by 17% as compared to the control, which was attributed to a 26% reduction of the G1 phase duration. No differences were observed in the duration of the S, G2 and M phases or in the [3H]TdR incorporation per S phase cell between the 35 g culture and the control. The induction of c-myc gene expression was investigated by RNA blot hybridization during a 15-360 min exposure of cells to 18, 35 and 70 g. Elevated levels of c-myc mRNA were observed after a 15-min exposure, and maintained after a 360-min exposure at all hypergravities examined. The highest induction rate of c-myc mRNA was 3.8-fold higher than the control after a 120-min exposure to 35 g. The 35 g condition was the most effective hypergravity for stimulating both cell proliferation and c-myc gene expression. Our study suggests that the appropriate level of hypergravity stimulates HeLa cell proliferation by reducing the G1 phase duration without affecting DNA synthesis rate, mediated through induction of c-myc gene expression.

Cell Cycle↗
PubMed1989

Effect of lithium carbonate administration singly or in combination with some psychotropic drugs on the radioiodide uptake by mouse thyroid.

The present study dealt with two objects; the first object was to examine whether or not lithium uptake in thyroid is modified by the thyroid state and how the intrathyroidal Li affects iodide uptake by the thyroid. Male and female mice were given lithium carbonate (Li) with propylthiouracil (PTU) or thyroxine (T4). Li was measured by a flameless atomic absorption spectrometry. The total Li content in thyroid was unaffected with PTU or T4, however, Li concentration per unit mass was reduced by PTU but unaffected by T4. The thyroid: serum ratio (T/S) of 125I resulted that the T/S became higher when Li concentration per unit mass was lower and vice versa, suggesting that Li uptake is controlled by thyroid states and Li in the gland interferes with the iodide uptake. Serum triiodothyronine (T3) and T4 by radioimmunoassay showed that PTU alone and in combination with Li lowered serum T4, while a high level of T4 by its supplement was suppressed by co-administration of Li. T3 level was lowered by Li alone, but not severely affected by other drugs. The results suggest that Li enhances T4 clearance without T4-T3 conversion. The second object was to examine the effect of combined psychotropic drugs on thyroid function. Carbamazepine (CBZ), haloperidol (HLP) and imipramine (IPA) were given singly or in combination with Li to examine their effects on the T/S of 125I. Only CBZ reduced the T/S but CBZ plus Li had no summative effect. Neither HLP nor IPA affected the T/S, singly or in combination with Li, suggesting that HLP or IPA does not interfere with an iodide pumping machinery. No distinct sex difference was observed in drug effects.

Animals↗
PubMed1989

[The effects of coronary thrombolysis on the short- and long-term mortality in acute myocardial infarction].

Among 263 patients with acute myocardial infarction, 141 were treated with urokinase (UK group) and 122 received no urokinase (conventional group). Urokinase (UK) was administered intracoronarily in 55 cases; intravenously (mainly 1,920,000 units) in 64 cases; and intravenously and intracoronarily in 22 cases. The mortality rates were ascertained three months after admission and during the mean follow-up periods of 17.5 months for the UK group and 24.5 months for the conventional group. The three month mortality was significantly lower in the UK group (10.6%, 15 cases) than in the conventional group (23.8%, 29 cases) (p less than 0.01). The mortality during the entire follow-up period was also lower in the UK group (14.2%, 20 cases) than in the conventional group (26.2%, 32 cases) (p less than 0.05). Fatalities due to cardiac rupture, ventricular fibrillation, cardiac failure, cardiogenic shock and recurrent infarction were uniformly less in the UK group. It was concluded that coronary thrombolysis is an effective means of reducing mortality in acute myocardial infarction.

Aged↗
PubMed1988

Enhancement of inositol phospholipid metabolism and activation of protein kinase C in ras-transformed rat fibroblasts.

The inositol phospholipid metabolism is one of the main pathways of signal transduction in cells. We measured the activities of its key enzymes in v-Ha-ras-transformed 208F rat fibroblasts. In the ras-transformed clones, incorporation of [32P]Pi into intermediates of the inositol phospholipid metabolism was stimulated. The activities of phosphatidylinositol and phosphatidylinositol-4-phosphate kinases in the transformed clones were about 35-50% more than in untransformed cells, indicating increased inositol phospholipid metabolism. However, the activity of diacylglycerol kinase in their membrane fraction was 25-35% less than that of untransformed cells, although the total diacylglycerol kinase activity did not change. The imbalance of these kinases could constitute one of the main reasons leading to the increased level of inositol phosphates and the accumulation of diacylglycerol to 2-2.2 times that in control 208F cells. Phosphatidylinositol-4,5-bisphosphate-phospholipase C activity did not change on the transformation when assayed under various conditions. The increased level of diacylglycerol caused intracellular translocation, activation, and down-regulation of protein kinase C changes which may be one of the essential events in transformation by the v-Ha-ras gene.

Animals↗
PubMed1988

Modified responsiveness of v-Ha-ras-transfected rat fibroblasts to growth factors and a tumor promoter.

The correlation of the phenotypic changes of v-Ha-ras transfected cells with the expression of p21ras and the modified responses to growth factors and a tumor promoter were examined. Transfection of the v-Ha-ras gene together with the neomycin-resistance gene into 208F rat fibroblasts yielded transformed clones characterized by morphological changes, anchorage-independent growth, and tumorigenicity in nude mice. The degrees of these biological alterations were parallel with the expression of mRNA and protein of the ras gene. In ras-transformed cells, anchorage-independent growth was stimulated by epidermal growth factor (EGF), insulin, bombesin, and fibroblast growth factor, whereas in the parental 208F cells, anchorage-independent growth was observed only in the presence of EGF, and there were many fewer EGF-induced colonies than those in the ras-transformed clones. A tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA) also augmented anchorage-independent growth of ras-transformed cells and induced morphological changes in monolayer cultures without altering the expression of the ras gene or phosphorylation of the p21ras protein. Retinoic acid inhibited the TPA-induced anchorage-independent growth. These results showed a good correlation of the expression of p21ras with the phenotypic changes and the increased sensitivity of the p21ras-expressing cells to the stimulation of growth factors and tumor promoter.

Animals↗