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Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 775 records · Page 43Linked to original sources
PubMed1993

Mutations in a protein tyrosine phosphatase gene (PTP2) and a protein serine/threonine phosphatase gene (PTC1) cause a synthetic growth defect in Saccharomyces cerevisiae.

Two protein tyrosine phosphatase genes, PTP1 and PTP2, are known in Saccharomyces cerevisiae. However, the functions of these tyrosine phosphatases are unknown, because mutations in either or both phosphatase genes have no clear phenotypic effects. In this report, we demonstrate that although ptp2 has no obvious phenotype by itself, it has a profound effect on cell growth when combined with mutations in a novel protein phosphatase gene. Using a colony color sectoring assay, we isolated 25 mutants in which the expression of PTP1 or PTP2 is required for growth. Complementation tests of the mutants showed that they have a mutation in one of three genes. Cloning and sequence determination of one of these gene, PTC1, indicated that it encodes a homolog of the mammalian protein serine/threonine phosphatase 2C (PP2C). The amino acid sequence of the PTC1 product is approximately 35% identical to PP2C. Disruption of PTC1 indicated that the PTC1 function is nonessential. In contrast, ptc1 ptp2 double mutants showed a marked growth defect. To examine whether PTC1 encodes an active protein phosphatase, a glutathione S-transferase (GST)-PTC1 fusion gene was constructed and expressed in Escherichia coli. Purified GST-PTC1 fusion protein hydrolyzed a serine phosphorylated substrate in the presence of the divalent cation Mg2+ or Mn2+. GST-PTC1 also had weak (approximately 0.5% of its serine phosphatase activity) protein tyrosine phosphatase activity.

Amino Acid Sequence↗
PubMed1993

A safe and simple technique for exchanging central venous catheters.

A safe and simple technique for exchanging central venous catheters is herein described. Our technique is based on a modification of Seldinger's method, in which a new outer sheath is introduced over the previous catheter as a guidewire in order to simplify the exchange of central venous catheters. This technique can be successfully performed by new residents and can be applied to the exchange of clotted catheters.

Catheterization, Central Venous↗
PubMed1993

123I-IMP SPECT brain imaging in epileptic psychosis: a study of two cases of temporal lobe epilepsy with schizophrenia-like syndrome.

To examine the relationship between functional abnormality of the brain and the development of epileptic psychosis, regional cerebral blood flow (rCBF) patterns with single photon emission computed tomography (SPECT) using N-isopropyl-(iodine-123)-p-iodoamphetamine (123I-IMP) were serially examined in interictal stages with and without the psychotic state in 2 medicated patients with temporal lobe epilepsy with schizophrenia-like syndrome. Both patients had epileptic EEG foci in the left temporal lobe and schizophrenia-like syndrome in Bruens' classification of epileptic psychosis, mainly consisting of auditory hallucinations and delusions of persecution and reference accompanying the enhancement of interictal epileptic discharges. In both patients, the SPECT scans obtained in the stages without the psychotic state revealed focal hypoperfusion images in the left temporal lobe regionally consistent with the EEG foci. On the other hand, the SPECT scans in the stages with the psychotic states revealed focal hyperperfusion images in the left temporal lobe or amygdala in case 1, and a normal perfusion pattern without asymmetric images of the right and left temporal lobes in case 2. These results suggest that temporo-limbic dysfunction, in particular hyperfunction in the temporo-limbic system in the left dominant hemisphere, arises at the time of the psychotic state in epileptic psychosis.

Adult↗
PubMed1993

Suppression of ventricular premature contractions continues after the washout of antiarrhythmic drugs.

The effects of the washout of antiarrhythmic drugs on the frequency of ventricular premature contraction (VPC) were investigated in 64 patients (VPCs > 2000/day). Included were patients on mexiletine (300-600 mg/day; 23 patients), disopyramide (300-600 mg/day; 19 patients) and atenolol (50 mg/day; 22 patients). Holter monitoring was repeated before, during and after the treatment with the above 3 drugs and the efficacies of the drugs were evaluated based on the spontaneous variability before the treatment. VPC reduction exceeding the calculated spontaneous variability during drugs therapy (drug-responders) and after the washout of the drugs (wash-responders) was noted in 17 (63%) and 3 (13%) of the mexiletine group; 11 (58%) and 5 (26%) of the disopyramide group; and 13 (59%) and 8 (36%) of the atenolol group, respectively. For the entire group of 64 patients, wash-responders were noted significantly (p < 0.05) more among drug-responders (14 of 41 patients; 34%) than drug-nonresponders (2 of 23 patients; 9%). Therefore, the antiarrhythmic effects of drugs observed during drugs therapy seem to continue even after the discontinuation of antiarrhythmic drugs in 34% of patients those whose VPC reduction exceeded the spontaneous variability (drug-responders).

Adult↗
PubMed1993

The relationship between serum lipoprotein(a) and restenosis after initial elective percutaneous transluminal coronary angioplasty.

The purpose of this study was to elucidate the possible link between lipoprotein(a) (Lp(a)) and the occurrence of restenosis after initial elective percutaneous transluminal coronary angioplasty (PTCA). Serum lipids, including Lp(a), total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol, apolipoprotein A-I (Apo A-I), and apolipoprotein B (Apo B), and the Apo B/Apo A-I ratio were examined in 63 consecutive patients (41 men and 22 women, average age 63 +/- 8 years) who underwent initial elective PTCA in our department. Forty two target lesions were in left anterior descending, 10 were in left circumflex and 11 were in right coronary branches. Restenosis was observed in 22 patients (35%) 6.4 +/- 2.6 months after PTCA. The serum Lp(a) level was significantly higher in the restenosis group than in the non-restenosis group (38.0 vs 19.9 mg/dl, p < 0.05). A significant correlation was observed between serum Lp(a) levels and the degree of % restenosis after PTCA (r = 0.557, p < 0.001). However, other lipids showed no significant relationship to restenosis. In addition, the % stenosis before PTCA was found to be related to the occurrence of restenosis after successful PTCA. We conclude that the serum Lp(a) level has a close correlation with the degree of % restenosis after PTCA, and may be a useful index for predicting the possibility of restenosis after PTCA, especially in patients with an Lp(a) level above 30 mg/dl.

Aged↗
PubMed1993

Hemodynamic effects of milrinone in patients with congestive heart failure--short- and long-term follow up studies.

The hemodynamic effects of milrinone (Mil) were studied in 11 patients with congestive heart failure (CHF) and New York Heart Association (NYHA) functional class II-IV before and after a 2-week treatment. The plasma concentration of Mil was also determined and its pharmacokinetics analyzed. The effect of a placebo was examined before the initiation of the treatment. At the onset, the hemodynamic effects of a single oral dose of Mil (7.5 mg) were evaluated. Mil increased the cardiac index significantly (p < 0.05) 4 h after administrations from 2.3 +/- 0.4 to 2.9 +/- 0.6 L/min/m2. The pulmonary capillary wedge pressure (PCW) was lowered significantly by Mil (p < 0.05) between 0.5 and 4 h after administration. After a 2-week treatment, the baseline PCW dropped (p < 0.05) and the NYHA functional class improved in 10 patients. One patient remained in the same class (II). The improved NYHA class was maintained in 6 patients tested after a mean interval of 16 +/- 3 months. Single oral administration of Mil (7.5 mg) induced hemodynamic improvements after 2-week treatment and the drug also induced similar improvements even after the chronic oral therapy with Mil for 16 +/- 3 months. Pharmacokinetic analysis showed a significant increase in the area under the curve after 2 weeks of treatment. We conclude that Mil decreases the PCW and probably increases the cardiac index and thus improves the symptoms and NYHA functional class in patients with CHF.

Aged↗
PubMed1993

Multiple coronary artery dissections diagnosed in vivo in a pregnant woman.

A 27-year-old, 37-weeks' primigravida survived an acute myocardial infarction. Coronary angiography 25 days after infarction demonstrated multiple dissections in the left coronary artery. She had no vascular risk factors or connective tissue disease. This is a rare case of spontaneous, multiple coronary artery dissections that were diagnosed by coronary angiography.

Adult↗
PubMed1993

Histochemical localization and X-ray microanalysis of calcium in the rat submandibular gland: demonstration of possible sites for microlith induction.

Rapidly frozen and freeze-substituted submandibular glands of young female rats were embedded in Epon and processed for histochemical demonstration of calcium with the glyoxal bis (2-hydroxyanil) (GBHA) staining method. GBHA staining of thick Epon sections revealed discrete calcium reactions of moderate intensity in practically every secretory granule but not in other compartments of the acinar cells. The saliva in the excretory duct was also reactive with GBHA and showed a drastic decrease in staining intensity toward the distal segments of excretory ducts with larger diameters. In addition, the duct saliva contained numerous tiny particles that were highly GBHA reactive. Stromal cells and cells lining the excretory duct were totally free of reactions. In the acinar cells, X-ray analysis detected distinct peaks for calcium in secretory granules and smaller ones in the Golgi apparatus, while they were undetectable in the rough surfaced endoplasmic reticulum (RER), implicating post-RER calcium loading in the secretory pathway. Electron-dense deposits in the duct saliva showed distinct peaks both for calcium and phosphorus, though these appeared in the acinar secretory granules and other cytoplasmic regions lacked phosphorus. Our observations thus demonstrated physiological calcium in the intra- as well as extracellular compartments of the submandibular gland, and further confirmed drastic changes in chemical composition along the synthetic and secretory pathways of the saliva, by both histochemical and X-ray microanalytical methods. GBHA staining of calcium combined with X-ray microanalysis is useful for an evaluation of the physiology and histo-pathological changes of the salivary glands associated with initial phases of microliths as well as sialoliths formation.

Aminophenols↗
PubMed1993

Postnatal development of periodontal innervation in rat incisors: an immunohistochemical study using protein gene product 9.5 antibody.

The postnatal development of innervation in the lingual periodontal ligament of rat incisors was investigated by immunohistochemistry using an antibody against protein gene product 9.5 (PGP 9.5), a neuron-specific protein. Immunostaining with the antibody enabled the clear demonstration of chronological alteration in the distribution and maturation of nerve terminals after birth. At 1 day after birth, thick nerve fibers showing PGP 9.5-immunoreactivity first appeared in the loose connective tissue corresponding to the future periodontal ligament, without forming an apparent terminal structure. At 4 days, two portions became distinguishable in the lingual periodontal ligament: alveolus- and tooth-related parts being comparable to those in the adult ligament. The immunoreactive nerve fibers increased in density and appeared to extend more incisally. Those restricted to the alveolus-related part showed ramifications with a small number of expanded or bulbous portions, and terminated among the periodontal fibers. Characteristic dendritic and expanded terminals, similar to Ruffini endings in the adult ligaments, began to occur in the lingual periodontal ligament at 7 days after birth and gradually increased in number until day 11 when the incisal edges emerged in the oral cavity. At approximately 15 days after birth, nerve endings possessing morphological features similar to Ruffini endings in adult rats were recognizable in the entire length of the periodontal ligament. After the eruption of first molars, the periodontal Ruffini endings drastically increased in number, and by the time the occlusion between the first molars was established, became identical in distribution and density to those seen in the lingual periodontal ligament of adult rat incisors. These findings suggest that the mechanical stimuli due to tooth eruption and occlusion might be a prerequisite for the final differentiation and maturation of the periodontal Ruffini endings.

Aging↗
PubMed1993

Sinusoidal vessels in the periodontal ligament of hamster incisors: their distribution, structure and possible function.

Vascular architecture in the periodontal ligament of hamster incisors was investigated by use of vascular casts under a scanning electron microscope (SEM). In addition to ordinary nutrient blood vessels, anastomosing vessels of large caliber developed, surrounding the incisor. From their characteristic configuration, these vessels were regarded as "sinusoids". The plexus of sinusoidal vessels was connected with capillaries in the papillary layer of the enamel organ at the labial periodontal ligament, and with veins penetrating into the alveolar bone on the lingual side. Transmission electron microscopic (TEM) observation showed that the sinusoidal wall was composed of only a thin layer of endothelial cells, lacking a smooth muscular element, and surrounded by densely arranged collagen fibers. Although the frequent association of Ruffini-type nerve endings with sinusoidal vessels was noted, neither direct contact nor specialized structures between these was recognizable. A possible function of the periodontal sinusoids is discussed on the basis of their distribution and ultrastructural evidence.

Animals↗
PubMed1993

Pure progressive autonomic failure presenting severe orthostatic hypotension.

A 59-year-old woman showed chronic progressive autonomic failure consisting of orthostatic hypotension and dyshidrosis. No signs of Parkinsonism, cerebellar or peripheral neuropathy were observed. Autonomic nervous function tests and findings of biopsied sural nerve suggested that this case had both sympathetic and parasympathetic dysfunctions, mainly postganglionic. A decrease in the total peripheral resistance and no increase in the heart rate on standing seemed to be the mechanism of orthostatic hypotension in this case. We conclude that pure PAF can be recognized as a distinct clinical syndrome of systematic degeneration of the autonomic nervous system.

Autonomic Nervous System Diseases↗
PubMed1993

Assessment of lymphokine-activated killer activity and gamma-interferon production in patients with small hepatocellular carcinomas.

We have previously reported depressed gamma-interferon production and depressed lymphokine-activated killer and natural killer activity in patients with relatively large hepatocellular carcinomas. These parameters were normal in cirrhosis. Some evidence had suggested a gamma-interferon production defect as the main cause of depressed lymphokine-activated killer activity in hepatocellular carcinoma, (i.e., gamma-interferon enhances lymphokine-activated killer and natural killer activity and gamma-interferon antibody inhibits lymphokine-activated killer induction). However, we were unable to clinically define the precise mechanism operating here because gamma-interferon production and lymphokine-activated killer activity were both defective in advanced hepatocellular carcinoma. In recent years, it has become possible to detect even small hepatocellular carcinomas on ultrasonography and to confirm them by fine-needle biopsy. In this study, we assessed those immune parameters in 48 patients with hepatocellular carcinomas less than 2 cm in diameter to confirm depressed immune function and to clarify the mechanism of these defects. Lymphokine-activated killer activity was defective in 31 patients (64.6%), whereas gamma-interferon production was defective in only 1 of these patients (2.1%). This observation argues against the hypothesis that defective gamma-interferon production is the primary defect and provides new insight into the mechanism of progression of defective immune function in hepatocellular carcinoma. Thirty-one of the 48 hepatocellular carcinoma patients were treated surgically, and these immune parameters were followed for 6 mo. The recovery of lymphokine-activated killer activity in all hepatocellular carcinoma patients with low lymphokine-activated killer activity suggests the tumor burden as the cause of defective lymphokine-activated killer activity.

Adult↗
PubMed1993

Depressed immune function in patients with cirrhosis before emergence of hepatocellular carcinoma.

Hepatocellular carcinomas 1 cm in diameter with high or low echogenicity can be detected on ultrasonography and confirmed on fine-needle biopsy, but it is still very difficult to detect small hepatocellular carcinomas with isoechogenicity. In this study, we assessed lymphokine-activated killer cell activity and interferon-gamma production prospectively every 1 to 3 mo for 23 +/- 4 mo (mean +/- 1 S.D.) in 227 patients with cirrhosis. Transient depression of lymphokine-activated killer activity was detected in 43 patients (defective lymphokine-activated killer group), and hepatocellular carcinoma was detected in 24 cases before the end of the 18-mo follow-up. Twenty-one (87.5%) of the 24 hepatocellular carcinoma patients were included in the defective lymphokine-activated killer group. Defective lymphokine-activated killer activity was detected more than 6 mo before detection of a space occupying lesion in the liver or elevation of alpha-fetoprotein level above 400 ng/ml. Serum alpha-fetoprotein level was elevated above 400 ng/ml in only five cases in which hepatocellular carcinoma was detected as a space-occupying lesion. Our results indicate that sequential assessment of lymphokine-activated killer activity may be a predictor of hepatocellular carcinoma and that the depression of immune function in cirrhotic patients is a serious risk factor for hepatocellular carcinoma emergence.

Adult↗
PubMed1993

[A case of acute coronary syndrome followed by 201Tl, 123I-BMIPP and 123I-MIBG myocardial imagings before and after PTCA].

201TlCl (Tl), 123I-beta-methyl-p-iodophenyl pentadecanoic acid (BMIPP) and 123I-metaiodobenzylguanidine (MIBG) images were applied before and after PTCA to a patient with acute coronary syndrome who had repeated ischemic attacks on light effort. A decreased tracer uptake was noted at the mid and apical anteroseptal regions in each image before PTCA. MIBG uptake was most decreased and Tl uptake was least decreased, but Tl uptake at exercise decreased as severely as MIBG uptake at rest. After PTCA an uptake was improved in each image. Both before and after PTCA, the area with decreased BMIPP uptake corresponded to the region with deteriorated wall motion obtained by echocardiography. It was suspected that the decreased MIBG uptake correlates with "area at risk" and that the decreased BMIPP uptake correlates with abnormal wall motion. Taken together those findings, it was indicated that an application of these cardiac scintigraphy is useful for the evaluation of comprehending metabolic abnormality and recovering process of ischemic myocardium.

3-Iodobenzylguanidine↗