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Biomedical subjects

K Maeda

Publications and source records attributed to K Maeda.

At least 955 records · Page 53Linked to original sources
PubMed1992

Melanocyte-stimulating properties of arachidonic acid metabolites: possible role in postinflammatory pigmentation.

Normal human epidermal melanocytes became swollen and more dendritic with an increase in the amount of tyrosinase and immunoreactive b-locus protein when they were cultured for 2 days with the following arachidonic acid metabolites: prostaglandin (PG) D2, leukotriene (LT) B4, LTC4, LTD4, LTE4, thromboxane (TX) B2 and 12-hydroxy eicosatetraenoic acid (12-HETE). The effect of LTC4 was particularly strong compared to that of PGE2, about which we have previously reported. On the other hand, PGE1, PGF2 alpha and 6-ketoPGF1 alpha did not show any significant stimulatory effect. These data suggest that arachidonate-derived chemical mediators, especially LTC4, may be responsible for the induction of post-inflammatory hyperpigmentation of the skin.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1992

[Long-term chemotherapy using erythromycin (EM) for chronic lower airway infection: effectiveness of clarithromycin in EM ineffective cases--the fourth report].

The effectiveness of long-term chemotherapy using Erythromycin (EM) for chronic lower airway infection has been practically proved. However, there still exist some ineffective cases, or cases in which the clinical effect was scarcely seen. In the present study was administered Clarithromycin (CAM) to such cases and found that CAM was effective in alleviating symptoms in some of them. The results were presented along with clinical findings and other basic studies. The subjects were 4 cases in which EM was either ineffective or low in its clinical effect. The subjects consisted of 1 case of DPB and 3 cases of bronchiectasis. EM was clinically ineffective in 2 cases and slightly effective in the two others. The pathogen was Pseudomonas aeruginosa in all cases. The dosage of EM was 200-1200 mg/day. The period of administration ranged from 2 years to 6 years 9 months. CAM was given orally after meals at a dose of either 200 or 400 mg/day. Chemotherapy had continued for 3-8 months at the time of final observation (Feb. 1992). Clinical effectiveness was evaluated on the basis of sputum volume and PaO2 examination, as well as evaluation by the patients themselves. As a result, in all 4 cases, reduction in sputum volume and improvement of PaO2 were observed. All subjects evaluated CAM therapy as being more effective than EM therapy. Moreover, it was found that CAM inhibited both the elastase and leucocidin produced in one of the ineffective cases by P. aeruginosa, whereas EM didnt.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[The 5th report on long-term chemotherapy using erythromycin (EM) for chronic lower airway infection--cases followed over 7 years].

Clinical studies were made over 7 years on 9 cases to whom long-term chemotherapy with EM was administered for chronic airway infection. 1) Clinical effectiveness: Highly effective in 8 cases; Improvement in QOL was observed in 8 cases. Bacteriological effect: In 7 cases, pathogenic bacteria disappeared. 2) No side effects were observed. 3) Changes in PaO2 levels with the passage of time: In most cases, PaO2 reached a plateau within 1 year. Although in some cases, there was subsequent elevation. 4) The frequency of catching cold over the 7 years period was low with an average of 1.2 times/year per subject. In only 2 cases were subject hospitalized due to acute exacerbation triggered by a cold. 5) Mucociliary transport improved in 7 out of 8 cases examined. However, only 4 of these recovered normal transport. The effect of EM in the other cases in which clinical improvement was not demonstrated was deemed slightly effective. On the basis of the above findings, it was suggested that long-term chemotherapy using EM was clinically efficacious. This is based on the fact that its efficacy, including amelioration of QOL appeared within one year of the initiation of therapy, and continued without decline for over 7 years.

Administration, Oral↗
PubMed1992

[A clinical study of respiratory tract infection due to Staphylococcus aureus detected by transtracheal aspiration].

A clinical study of 24 patients with respiratory tract infection due to S. aureus detected by transtracheal aspiration (TTA) was conducted, and the following results were obtained. 1) The detection frequency of S. aureus was relatively low (4.6%). 2) Pneumonia was the principal clinical manifestation. 3) Approximately one half of the patients had previously received antimicrobials. 4) Multiple organisms were frequently detected, particularly in cases of hospital-acquired infection. H. influenzae was the most frequently simultaneously detected organism. 5) On sputum examination, approximately 20 ml of purulent sputum was found in most cases, and S. aureus was detected in sputum specimens from 20 of the patients. 6) The largest number of cases was found in 1987. Onset was most common from autumn to spring. 7) Undernutrition was the most frequently associated host factor. As indicated by the above findings, the clinical expression of S. aureus infection is variable, and it is important that it be diagnosed accurately.

Adult↗
PubMed1992

[The long-term chemotherapy with erythromycin (EM) in chronic lower respiratory tract infections--third report: clinical study of cases administered EM over 3 years].

An investigation was made of the use of EM therapy which began in 1986 or earlier in 31 cases with chronic lower respiratory tract infections. 1) Of the 20 cases in which EM (Erythromycin stearate) administration (600-1200 mg/day) was continued for 3 years or more and its usefulness could be evaluated, treatment with this agent was judged markedly effective in three, effective in 14, somewhat effective in two, and ineffective in one. This amounted to an effectiveness rate (effective or better) of 85%. 2) Improved QOL was observed in 15 of the 20 cases. 3) In the Pseudomonas infected cases, a discrepancy was seen between the effectiveness rate of 87.5% and the disappearance rate of the organism (12.5%), while in the Haemophilus cases no such discrepancy was found (75%). 4) EM administration was stopped in 11 cases because of side effects in two (stomatitis, gastrointestinal disorder) death in five, desire of the patient in three, and transfer to another hospital in one. The cause of death cases had no connection with administration of EM. 5) In the three patients who stopped EM on their own, the agent was again administered because of exacerbation of symptoms, although this readministration proved ineffective in two of the cases. The above results suggest that long term EM therapy is useful and that its continued administration is important.

Adult↗
PubMed1992

[Three cases of lower respiratory tract infection worsened after rhinovirus infection].

We experienced three cases of lower respiratory tract infections worsened after Rhinovirus infection. Case 1: A 42-year-old male with diffuse panbronchiolitis was admitted to our hospital with the complaint of dyspnea on November 21, 1988. Rhinovirus was isolated from nasal washing and P. aeruginosa was cultured from transtracheal aspiration (TTA). Case 2: A 67-year-old male, whose underlying disease was pulmonary asbestosis, was admitted to our hospital complaining of pyrexia on June 12, 1990. Rhinovirus was isolated from TTA and H. influenzae and others were cultured from TTA. Case 3: A 64-year-old male with pulmonary emphysema was admitted to our hospital with a complaint of dyspnea on August 11, 1989. On December 17, 1989 the patient developed rhinorrhea and complained of purulent sputum, pyrexia and dyspnea after five days. Rhinovirus was isolated from nasal washing and TTA and S. nonhaemolyticus and others were cultured from TTA. As indicated in this report, it is interesting to study the relationship between viral infection of the upper respiratory tract and bacterial infection of the lower respiratory tract.

Adult↗
PubMed1992

Effects of transplants of fetal mediobasal hypothalamus on luteinizing hormone pulses impaired by hypothalamic deafferentation in adult ovariectomized rats.

Pulsatile luteinizing hormone (LH) secretion is impaired after posterior anterior-hypothalamic deafferentation (PAD), which separates the anterior part of the arcuate nucleus from the mediobasal hypothalamus (MBH). In the present study, we examined whether transplants of fetal brain tissue could prevent the effects of PAD. The brain tissue containing the MBH or the cerebral cortex taken from the fetal brain was transplanted into the third ventricle of ovariectomized rats. Four weeks after the brain transplantation, animals with or without the brain transplantation were subjected to PAD. One week after PAD, blood samples were collected every 6 min for 3 h through an indwelling atrial cannula. Rats bearing PAD without transplantation showed irregular pulsatile fluctuation of plasma LH, whereas LH pulses were maintained in rats bearing transplantation of the fetal MBH tissue. In rats which had been transplanted with the cerebral cortex, LH pulses were less apparent after PAD than in the MBH-transplanted or sham-deafferentated animals. No cell bodies of LH-releasing hormone (LHRH) neurons were found immunohistochemically in the MBH grafts. These results suggest that the graft containing the fetal MBH tissue maintains regular LH pulses after PAD and that the LHRH pulse generator may consist, at least in part, of a group of neurons in the MBH other than LHRH-producing neurons.

Animals↗
PubMed1992

Alpha 2-adrenergic receptors are involved in the suppression of luteinizing hormone release during acute fasting in the ovariectomized estradiol-primed rats.

It has been previously reported that the adrenergic system is involved in the control of feeding behavior and LH release. In the present study, the role of the adrenergic receptors in the suppression of LH release during acute fasting are examined by injecting the alpha 1-antagonist (prazosin), alpha 2-antagonists (idazoxan, SKF 86466-A, piperoxan), or beta-antagonist (propranolol) into the third ventricle of unfasted and 48 h fasted ovariectomized estradiol-treated rats. Blood samples were collected every 6 min for 3 h and the drugs were administered after the first hour of the sampling period. Prazosin caused a significant suppression of LH release in the unfasted animals while idazoxan and propranolol had no significant effects. In contrast, all alpha 2-antagonists blocked the inhibitory effect of fasting on LH release and significantly reinstated the suppressed LH release while prazosin and propranolol had no significant effects. We conclude from these results that the suppression of LH release during acute fasting is mediated by alpha 2-adrenergic receptors but not alpha 1- or beta-adrenergic receptors.

Adrenergic alpha-Antagonists↗
PubMed1992

Suppressed serum and urine levels of indoxyl sulfate by oral sorbent in experimental uremic rats.

In uremic patients, the serum concentration of indoxyl sulfate is markedly increased. To determine if oral sorbent (AST-120) suppresses the endogenous synthesis of indoxyl sulfate, it was administered to experimental uremic rats, and the serum concentration and urinary excretion of indoxyl sulfate were quantified by high-performance liquid chromatography. Oral sorbent decreased both the serum concentration and urinary excretion of indoxyl sulfate, suggesting that there was suppression of the endogenous synthesis of indoxyl sulfate by the oral sorbent. Oral sorbent did not decrease the serum concentration and urinary excretion of hippuric acid, but it did alleviate the deterioration of renal function in the experimental uremic rats.

Adsorption↗
PubMed1992

Induction of irreversible glomerulosclerosis in the rat by repeated injections of a monoclonal anti-Thy-1.1 antibody.

The present experiment demonstrated that an irreversible glomerulosclerosis could be induced in the rat through repeated intravenous administrations of OX-7 (a monoclonal anti-Thy-1.1 antibody). Rats were injected with 0.2 mg of affinity-purified OX-7 at 1-week intervals for a period of 4 weeks. Glomerular damage was periodically examined at light-microscopic level. Thirty-five days after the initial injection (7 days after the final injection), capillary aneurysms and expansion of the mesangial areas with hypercellularity were frequently observed. Similar glomerular damage was also observed in rats 7 days after they received a single injection of either 1.0 or 0.2 mg of OX-7. After repeated injections, 112 days from the initial administration (84 days after the final injection), approximately 60% of the glomeruli had expanded mesangial areas with an apparent increase in the mesangial matrix. The result contrasts sharply with that obtained from a single injection of OX-7 in that more than 85% of the glomeruli showed no abnormalities 84 days after the injection. This chronic model, as a result of repeated injections of the antibody, could serve as a potential for further investigation of the mechanisms involved in the development of chronic glomerulonephritis.

Animals↗
PubMed1992

Fluid-phase activation of the alternative pathway of complement by excess factor D in regularly dialyzed patients.

We examined the effect of excess factor D on the alternative pathway of complement (APC). First, we demonstrated that the production of C3a is accelerated in the fluid-phase with the addition of purified factor D. Analysis by sodium dodecylsulfate polyacrylamide gel electrophoresis under reducing conditions showed that the serum iC3b level was elevated when incubated with excess factor D. Secondly, we demonstrated, by measuring the C5a-des-Arg level, that the generation of C5a was promoted in the fluid-phase with the addition of purified factor D. We then studied whether activation of APC is elevated in the blood of patients on maintenance hemodialysis whose sera contained a high concentration of factor D. First, we detected, by fluorescence activated cell sorter analysis, greater amounts of C3d on erythrocytes from the patients (mean fluorescence intensity +/- SD: 7.7 +/- 1.7 arbitrary units) than those from healthy individuals (5.4 +/- 0.5 arbitrary units; p less than 0.001). Secondly, serum C3 level was significantly lower (p less than 0.001) in patients (mean +/- SD: 63.3 +/- 8.2 mg/dl) than in healthy individuals (84.8 +/- 9.5 mg/dl), whereas there was no difference in serum C4 level between patients (32.4 +/- 6.9 mg/dl) and healthy individuals (33.0 +/- 7.4 mg/dl). Serum C5 level was almost the same in patients (10.5 +/- 1.5 mg/dl) and in healthy individuals (11.2 +/- 1.3 mg/dl). These results provide supportive evidence of elevated APC activation in patients with high serum factor D.

Blood Circulation↗
PubMed1992

Obstruction of inferior vena caval orifice by giant left atrium in patients with mitral stenosis. A Doppler echocardiographic study from the right parasternal approach.

BACKGROUND: To examine whether an extremely enlarged left atrium (giant left atrium) obstructs the venous return from the inferior vena cava (IVC), the velocity of IVC flow was measured at its junction with the right atrium (IVC orifice) in patients with mitral stenosis by use of color and pulsed-wave Doppler echocardiography from a right parasternal longitudinal plane. METHODS AND RESULTS: The maximum dimension of the IVC orifice by two-dimensional echocardiography and the maximum IVC orifice flow velocity by pulsed-wave Doppler echocardiography were measured in 74 patients with mitral stenosis and atrial fibrillation (mean age, 59 years). The control population consisted of 16 subjects with atrial fibrillation alone (mean age, 61 years). Flow velocities in the superior vena cava and hepatic vein were also obtained by pulsed-wave Doppler echocardiography from the supraclavicular and subcostal views, respectively. Fifty-one mitral stenosis patients without severe tricuspid regurgitation were divided into two groups according to the left atrial dimension (LAD), which was measured by the standard left parasternal long-axis view (group A: n = 33, LAD less than 65 mm; group B: n = 18, LAD greater than or equal to 65 mm). Peak inspiratory and expiratory velocities of IVC orifice flow in diastole averaged over three consecutive inspirations in group B (mean +/- SD, 93.4 +/- 32.0 and 47.6 +/- 19.8 cm/sec) were significantly greater (p less than 0.01) than in the control subjects (67.9 +/- 12.8 and 34.5 +/- 7.0 cm/sec) and in group A (70.2 +/- 18.4 and 38.1 +/- 11.5 cm/sec, respectively). However, there were no significant differences in superior vena caval and hepatic vein flow velocities among the three groups. The maximum IVC orifice dimension in group B (11.4 +/- 4.4 mm) was significantly smaller than in the control subjects (20.1 +/- 2.1 mm) and in group A (18.6 +/- 5.4 mm) because of displacement of the atrial septum into the right atrium. There were significant negative correlations between the IVC orifice dimension and the peak IVC orifice flow velocity (r = -0.62, SEE = 0.33 cm/sec, n = 67, y = e(-0.01x + 3.6), p less than 0.01) as well as the left atrial dimension (r = -0.71, SEE = 0.32 mm, n = 67, y = e(-0.02x + 3.8), p less than 0.01) in these 51 patients and control subjects. In the remaining 23 patients with severe tricuspid regurgitation, the peak inspiratory IVC orifice velocity (n = 9, 88.6 +/- 30.0 cm/sec) was significantly greater (p less than 0.05) and the IVC orifice dimension (23.8 +/- 9.7 mm) significantly smaller (p less than 0.05) in patients with a giant left atrium than in those without (n = 14, 69.9 +/- 15.3 cm/sec and 30.5 +/- 9.6 mm, respectively); in the latter, the IVC orifice dimension was significantly (p less than 0.05) greater than in the controls. CONCLUSIONS: A giant left atrium in patients with mitral stenosis obstructs venous return at the IVC orifice by marked displacement of the atrial septum toward the right atrium.

Adult↗
PubMed1992

Involvement of the gastric vagal nerve in the suppression of pulsatile luteinizing hormone release during acute fasting in rats.

Acute fasting has been shown to impair gonadotropin secretion in an estrogen-dependent manner in rats. The present study examined whether the vagus nerves have some role in the suppression of pulsatile LH release after 48-h fasting in ovariectomized estradiol-treated rats by performing complete subdiaphragmatic cutting of the nerves or selective sectioning of its branches (gastric, hepatic, or celiac) after the first hour of a 3-h blood sampling period. Vagotomy, alone, did not cause any changes in LH release in the unfasted animals. However, complete and gastric vagotomies restored pulsatile LH release that was suppressed before the nerves were cut in fasted animals. Neither hepatic nor celiac vagotomy restored pulsatile LH release, which remained suppressed throughout the sampling period in fasted animals. These results suggest that some mechanism involving the afferent vagal nerves, particularly the gastric vagus, has a major role in the suppression of pulsatile LH release during acute fasting in ovariectomized estradiol-primed rats.

Animals↗
PubMed1992

Intravascular ultrasound imaging--in vitro and vivo validation.

Intravascular ultrasound imaging is a new technique for visualizing arterial structures. The purpose of this study was twofold; first, to assess the ability of this intravascular ultrasound catheter to generate cross-sectional images of human artery segments in vitro and second, to determine the reliability of intravascular ultrasound technique in the evaluation of human arteries in vivo. For the vitro study, ultrasound images of the arteries were presented as a two-dimensional, 360 degrees display of vessel cross-section perpendicular to the long-axis of the probe. The ultrasound scanning provided an accurate description with high resolution of lumen structure and lumen-intima interface in all vessel specimens. There was a good correlation between the planimetric luminal area on the ultrasound images and the area obtained from histologic images (r = 0.92). There was also a good correlation in the plaque thickness between ultrasound and histological examination (r = 0.88). In the in vivo study, the ultrasound catheter was easily introduced, readily manipulated, and images were successfully obtained in all patients. No untoward effects were noted during manipulation of the catheter. There was a good correlation in the arterial dimension between ultrasound and angiographic measurements (r = 0.93). Thus, intravascular ultrasound imaging appears to be useful for characterizing and quantitating arterial lesions.

Carotid Arteries↗
PubMed1992

Effects of placing micro-implants of melatonin in the mediobasal hypothalamus and preoptic area on the secretion of prolactin and beta-endorphin in rams.

In a previous study, we showed that the local administration of melatonin in the mediobasal hypothalamus (MBH), but not the preoptic area (POA), caused a premature increase in the secretion of FSH and growth of the testes in sexually inactive Soay rams exposed to long days. To extend these observations, we have now measured blood concentrations of prolactin and beta-endorphin and the associated peripheral responses in the same animals, to establish whether the treatments produced multiple endocrine changes such as those which occur following exposure to short days. Groups of rams were initially exposed to alternating 16 weekly periods of long days (16 h light: 8 h darkness; 16L:8D) and short days (8L:16D) for at least 9 months to entrain the seasonal cycles in the secretion of the pituitary hormones. The treatments were started at 10 weeks under long days, when the animals had a physiology characteristic of the early summer with high blood plasma concentrations of prolactin (associated with growth of the summer pelage), and low concentrations of beta-endorphin (associated with low body weight). The animals were assigned at random to the following treatments: (i) micro-implants of melatonin in the MBH, (ii) microimplants of melatonin in the POA, (iii) empty implants in the MBH or POA to act as operated controls, and (iv) no surgery to act as unoperated controls (n = 12 rams/treatment). The micro-implants consisted of 22-gauge stainless-steel needles with melatonin fused inside the tip. The implants were inserted bilaterally in the brain, and left in place for 12-14 weeks. The observations continued for a total of 28 weeks while the animals remained under long days. The administration of melatonin in the MBH induced a rapid decreased in plasma concentrations of prolactin while in the POA it induced a less marked but significant effect. The mean times to minimum concentrations of prolactin were 7.4 +/- 0.4, 17.3 +/- 2.8 and 26.0 +/- 0.3 weeks for the MBH, POA and combined control groups respectively (MBH vs control, P < 0.001, POA vs control P < 0.01). In the MBH group, the concentrations of prolactin subsequently increased to a maximum 6 weeks after the end of melatonin treatment. The changes in prolactin were accompanied by changes in growth and moulting of the pelage; only animals in the MBH group showed a conspicuous moult associated with the change from low to high prolactin secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

[Stability of body composition in boys and girls 12 through 15 years of age].

Although underwater weighing has been regarded as a representative of the criterion reference methods for determining body composition, this technique is cumbersome for screening. The purpose of the present study was to examine the stability of body composition assessed not only by underwater weighting but also by existing bioelectrical impedance equations and skinfold thickness equations during a 4-week period. Ten male and 10 female junior high school pupils, aged 12 to 15 years, volunteered to serve as subjects. Body density (Db) was estimated by underwater weighing (UW), skinfold thickness (ST) method, and bioelectrical impedance (BI) method. The UW was considered criterion reference method. The underwater weight was the heaviest value that was reproduced twice at least among 5 to 10 measurements. Residual lung volume was estimated "in water," with the subject in the sitting position, by a closed-circuit helium-dilution method. The ST equations used for determination of Db were those developed by Nagamine et al., while in the BI method equations proposed by Nakadomo et al. were applied. The Db for boys by UW did not differ significantly during the 4-week period; however, in girls it was significantly lower in the 2nd test (1.0479 +/- 0.018 g/ml) than in the 1st test (1.0500 +/- 0.019 g/ml). Likewise, the Db estimated by ST and BI methods remained unchanged in boys, while in girls it was significantly lower in the 2nd test (BI: 1.0445 +/- 0.010 vs. 1.0389 +/- 0.013 g/ml). Test-retest reliability of all the three methods for measurements conducted 4 weeks apart were statistically significant (e.g. UW: r = 0.99, ST: r = 0.94, BI: r = 0.89 in girls). In conclusion, the validity of Db estimated by these two methods was found to be insufficient when absolute values are required. However, body composition estimates assessed by ST and BI methods for boys and girls may be stable on a relative basis.

Adolescent↗
PubMed1992

Hypereosinophilic syndrome accompanied with necrosis of finger tips.

We report a case of hypereosinophilic syndrome (HES) with marked eosinophilia (59.7%) and mononeuritis multiplex (upper limbs and buttocks). Necrosis of the finger tips was the primary manifestation which simultaneously occurred on both sides. These clinical manifestations were improved dramatically by subsequent steroid therapy. Interestingly, an elevation of serum tumor necrosis factor (TNF) was observed. These findings suggest that TNF may play a role in the etiology of necrosis of the finger tips.

Adult↗