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Biomedical subjects

F Ikeda

Publications and source records attributed to F Ikeda.

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

[Formation of biofilm by slime producing Staphylococcus epidermidis and bactericidal activity of cefazolin].

Slime production was studied in a total of 598 strains of Staphylococcus aureus and 11 species of coagulase negative staphylococci and the relationship of the slime production and biofilm formation was investigated. The high slime production was obtained in 42 of 263 strains (16%) of S. epidermidis only. The adherence of S. epidermidis to biomedical silicone discs (S discs) and biofilm formation were investigated in vitro in high slime producing and non-producing strains. The adherence rates of S. epidermidis to the S discs ranged from 2.3 to 14.8%. There was no relationship between slime production by S. epidermidis and the adherence rates. Biofilm was formed only in slime producing strains with cell growth on the S discs when they were incubated. The process of the biofilm formation was obtained by scanning electron microscopy; there were many projections, probably slime secreted from the cells, on the cell surface, and picture showing agglutination of cell by crosslinking. The bactericidal activity of cefazolin, cefmetazole and flumoxef against S. epidermidis after formation of the biofilm decreased more markedly than that before formation. Cefazolin reduced the number of S. epidermidis and eliminated the formed biofilm in an in vitro simulation model of serum concentration in human after drip infusion of 2 g of cefazolin.

Cefazolin↗
PubMed1990

Intrinsic penicillin resistance in penicillinase-producing Neisseria gonorrhoeae strains.

The minimal inhibitory concentrations (MICs) of ampicillin for fifty strains of beta-lactamase-producing Neisseria gonorrhoeae (PPNG) isolated in Japan ranged from 1.56 to 200 micrograms/ml, and all the strains harbored a 4.5 megadalton plasmid. These strains were classified into two groups: dicloxacillin-susceptible (28%) and -resistant group (72%). A linear correlation was found in the dicloxacillin-susceptible strains between their beta-lactamase activity and the susceptibility to ampicillin, but not in the dicloxacillin-resistant strains. This suggests that the high ampicillin resistance in PPNG is due not only to acquiring the beta-lactamase producing plasmid, but also to some intrinsic resistance of the strains. To investigate a cause of the high ampicillin resistance, the beta-lactamase-producing plasmid, pTMS1, was transferred by conjugation to a penicillin-susceptible gonococcal strain as well as to its isogenic multiply antibiotic-resistant transformants, and the susceptibility of the transconjugants to ampicillin was determined. Acquisition of pTMS1 by a penicillin-susceptible strain resulted in a 32-fold increase in resistance to ampicillin, whereas the increase was 128-fold for its isogenic strains which contain some chromosomal mutations. These results suggest that reduced permeability of the outer membrane to ampicillin underlies the high ampicillin resistance of PPNG.

Conjugation, Genetic↗
PubMed1990

Activity of cefixime against Helicobacter pylori and affinities for the penicillin-binding proteins.

Cefixime induced the formation of rounded cells from the spiral bacillary form of Helicobacter pylori at the MIC or less. Three main penicillin-binding proteins, called A, B and C, were separated from H. pylori. Cefixime had the strongest affinity to penicillin-binding protein B. The binding of cefixime to this protein may induce the formation of rounded H. pylori cells.

Anti-Infective Agents, Urinary↗
PubMed1990

Venous flow in the great cardiac vein of the dog.

The venous blood flow in the great cardiac vein (GCV) was measured with an ultrasonic transit-time flowmeter during brief occlusion of major branches of the coronary arteries in open-chest dogs. Occlusion of the right coronary artery did not affect GCV outflow. GCV outflow vanished when the left anterior descending artery (LAD) was occluded proximal to the bifurcation of the septal artery. When the LAD was occluded distal to the septal artery, the GCV flow reduction averaged 70%. Occlusion of the left circumflex artery resulted in a slight but significant decrease, followed by an increase in GCV outflow. Partial occlusion of the coronary sinus or GCV by a catheter resulted in a decrease in outflow. This suggests that the absolute value of coronary venous flow obtained by the thermodilution technique should be evaluated carefully.

Animals↗
PubMed1990

[Left ventricular performance following mitral valve replacement in patients with tight mitral stenosis combined with mild aortic regurgitation].

The severity of aortic regurgitation is difficult to estimate prior to mitral valve replacement (MVR) in cases with tight mitral stenosis (MS), because low output state due to mitral obstruction masks signs of aortic regurgitation. This study clarified left ventricular performance, possibly affected by increased diastolic loading after MVR. The study subjects consisted of 12 patients with pure mitral stenosis (MS group) and 11 with combined mitral stenosis and aortic regurgitation (MSAR group). The diagnosis was made by cardiac catheterization preoperatively. The aortographic grade of aortic regurgitation was class 1 or 2 according to the AHA classification. Both groups were matched in terms of severity in mitral obstruction evaluated by mitral valve area. On preoperative echocardiographic evaluation, there was no difference in the mean values of LVDd, LVSd, and %FS between the groups MS and MSAR. After surgery, symptoms improved in each patient. Echocardiography performed three months after MVR revealed no differences in these parameters between both the groups. We concluded that aortic regurgitation evaluated as class 1 or 2 preoperatively does not increase in respect to left ventricular diastolic overloading and echocardiographic left ventricular performance remains unchanged.

Adult↗
PubMed1989

[Hemodynamic sequelae following valve replacement in patients with aortic regurgitation].

Serial echocardiographic analyses of the left ventricle (LV) were performed in 61 patients with aortic regurgitation before, one-six months, and six years after aortic valve replacement (AVR). There was no significant difference in the preoperative hemodynamic and echocardiographic data between 54 survivors and six deceased patients. There was a linear correlation (r = 0.69) between LV end-diastolic volume (EDV) by cineangiography and LV end-diastolic dimension (LVDd) by echocardiography. In patients with LV end-diastolic pressure (EDP) less than 12 mmHg, the LV was markedly dilated before surgery, and LVDd was not normalized until half a year after surgery in half the cases. In 20 patients with LVEDP greater than 12 mmHg, LVDd was normalized in 17 patients up to half a year after surgery. In 11 patients with LV end-systolic dimension (LVDs) greater than 5.2 cm, LVDs was not normalized until six years post surgery in three patients. LVDd was improved six years after surgery in patients with LVDs less than 5.2 cm. Echocardiographically-determined LVDs less than 5.2 cm is recommended for preservation of LV function following aortic valve replacement.

Adult↗
PubMed1988

Novel plasmid-mediated beta-lactamase from Escherichia coli that inactivates oxyimino-cephalosporins.

A highly cephem-resistant Escherichia coli strain, FP1546, isolated from the fecal flora of laboratory dogs previously administered beta-lactam antibiotics was found to produce a beta-lactamase, FEC-1, of 48-kilodalton size and pI 8.2. FEC-1 hydrolyzed cefuroxime, cefotaxime, cefmenoxime, and ceftriaxone, as well as the enzymatically less-stable antibiotics cephaloridine, cefotiam, and cefpiramide. Of the oxyimino-cephalosporins, ceftizoxime was fairly stable to FEC-1. FEC-1 differed notably from chromosomal E. coli cephalosporinase, especially in its broad-spectrum substrate profile and its high inhibition by clavulanic acid, sulbactam, and imipenem. A conjugation study revealed that FEC-1 was encoded by a 74-megadalton plasmid, pFCX1. This may be the first instance of a plasmid-mediated oxyimino-cephalosporinase from E. coli.

Animals↗
PubMed1987

Absent aortic valve with normally related great arteries.

A neonate with absent aortic valve associated with membranous mitral atresia and normally related great arteries is reported. The patient was a 3360-g boy and was transferred to our hospital 4 h after birth because of severe cyanosis and respiratory distress. Absent aortic valve associated with mitral atresia was diagnosed on echocardiography. The patient died 4 days later with congestive heart failure. Postmortem examination revealed the aortic valve and sinus of Valsalva to be totally absent. The mitral valve showed membranous atresia. Severe endocardial fibroelastosis of the left ventricle, which was mildly dilated, and bizarre trabeculation were seen. This is the first case report of an absent aortic valve with normally related great arteries.

Aortic Valve↗
PubMed1987

Spontaneous growth hormone secretion and plasma somatomedin-C in children of short stature.

We studied 17 short prepubertal children, aged 7.5 to 17.0 years (mean +/- SD: 11.7 +/- 2.4) more than 2.0 SD below the mean height for their age and of delayed bone age (M +/- SD: 8.1 +/- 2.3), to clarify their physiological GH secretory status. The mean concentration of GH (MCGH) was calculated and was compared with the subjects' GH responses to insulin and arginine tolerance tests (IATT) and plasma somatomedin-C (SM-C). The mean 24-h MCGH value was 3.2 +/- 1.3 ng/ml (range 1.6-5.5). The mean peak GH response to the IATT was 13.0 +/- 7.5 ng/ml (range 2.4-33.9). In addition to the two patients with abnormally low GH responses to the IATT, seven with normal responses showed low 24-h MCGH values, a small number of GH pulses and low mean GH amplitude. The mean plasma SM-C in all patients was 0.60 +/- 0.20 U/ml. This was significantly lower than that of age-matched children of normal height (p less than 0.001). The 24-h MCGH was significantly correlated with plasma SM-C levels (r = 0.51, p less than 0.05) and with that of the first three hours of sleep at night (r = 0.84, p less than 0.01). These results indicate that: 1) some short children with normal GH response to pharmacological tests secrete a low amount of GH physiologically and 2) blood sampling during the first three hours of sleep as well as 24-hour sampling is suitable in evaluating the physiological secretion of GH.

Adolescent↗
PubMed1987

[A case of three malignant tumors of the duodenal bulb and large intestine].

A 75-year-old woman with anemia admitted to our hospital and was found to have a polyp in the duodenal bulb. The biopsy specimen was histologically diagnosed as an adenoma. A barium enema examination showed an obstruction in the ascending colon and a biopsy done on a specimen of the ascending colon revealed colonic cancer. A histology of the resected specimen of the duodenal bulb revealed a tubular adenocarcinoma in an adenoma, and a similar examination of a colonic resected specimen revealed a mucinous, papillary carcinoma. A primary malignant tumor in the duodenum is an uncommon tumor and our case is first in Japan showing three malignant tumors with an early duodenal cancer.

Adenocarcinoma, Mucinous↗
PubMed1986

Aliphatic side chain of catecholamine potentiates the stimulatory effect of the catechol part on the synthesis of nerve growth factor.

Catecholamines are potent in stimulating nerve growth factor (NGF) synthesis in mouse L-M cells. The relationship between the structure of catecholamines and their stimulatory effect on NGF synthesis has been studied using various 3,4-dihydroxyphenyl derivatives or their analogues. All 3,4-dihydroxyphenyl derivatives with two saturated carbons on the side chain were potent stimulators, whereas those with only one carbon on the side chain were weak stimulators. Drugs lacking the catechol ring were not effective. These results suggest that the catechol part of catecholamines is essential for the stimulatory effect and that the aliphatic side chain potentiates this effect. The present results also suggest the terminal amino residue on the side chain is not critical for the effect.

Animals↗
PubMed1986

Conjugal transfer of beta-lactamase-producing plasmids of Neisseria gonorrhoeae to Neisseria meningitidis.

Twenty clinical isolates of beta-lactamase-producing Neisseria gonorrhoeae from Japanese sources were studied to define their ability to serve as donors for their plasmids in conjugation with Neisseria meningitidis. These twenty strains of N. gonorrhoeae harbored the 4.5-megadalton (Mdal) beta-lactamase-producing plasmids and the 24.5-Mdal conjugative plasmids. We found that only three of twenty N. gonorrhoeae strains showed a detectable conjugation frequency (greater than 10(-5)) with N. meningitidis as the recipient although all strains were capable of mobilizing beta-lactamase-producing plasmids to N. gonorrhoeae and to Escherichia coli. The 4.5-Mdal beta-lactamase-producing plasmid was maintained in N. meningitidis, but the large 24.5-Mdal conjugative plasmid has not been found in N. meningitidis transconjugants.

Bacterial Proteins↗
PubMed1985

Responses of patients with Bartter's syndrome to angiotensin III and angiotensin II-(3-8)-hexapeptide.

Studies were conducted to determine whether or not angiotensin III [AIII] and angiotensin II-(3-8)-hexapeptide [ANG-(3-8)] have their own specific arteriolar binding sites different from angiotensin II [AII] binding site(s) in man. Four patients with Bartter's syndrome were given asn1-,val5-AII by iv infusion at rates of 10, 20, 50 and 100 pmol/kg X min, each for 7 min. One hour later AIII was infused iv in the same 4 patients at rates of 50, 100, 250 and 500 pmol/kg X min, each for 7 min. After 100 or 150 mg/day of indomethacin treatment for 7 days, the same AII and AIII infusions were repeated. All patients showed blunted pressor responses to both AII and AIII before indomethacin and the responses were improved after indomethacin. Moreover, increment curves of blood pressure for AII were almost identical with those for AIII in individual patients both before and after indomethacin. ANG-(3-8) was infused iv in 3 normal men and 3 of the 4 patients with Bartter's syndrome at a rate of 3.500 pmol (2.838 ng)/kg X min for 15 min. Blood pressure rose in the normal men (12/12 mmHg on the average) but did not rise in the patients. These results suggest that AII, AIII and ANG-(3-8) have the same arteriolar binding sites in man.

Adolescent↗
PubMed1985

Functional visual field of patients with visual field loss.

To assess the capability of perceiving forms in patients with visual field loss, a concept of functional visual field was introduced based on determinations of the time required for pattern recognition. Two series of stimulus patterns were made of Japanese syllabic hiragana characters drawn with black dots in the background of open circles of various sizes: the clear stimulus had only open circles in the background and the noisy stimulus had black dots scattered in the background. The stimuli were presented for various durations to 15 normal subjects and 25 patients with narrowed visual field; a correlation of the percentages of correct pattern recognition with the stimulus durations permitted calculations of the 50% recognition time. The recognition time was longer with the noisy than with the clear stimuli. The recognition time with a given stimulus size was longer in patients than in normal subjects. In 3 normal subjects the visual field was artificially narrowed and the recognition time was determined. The recognition time could be expressed by a power function of the ratio of the effective visual field diameter to the diameter of the stimulus pattern. On this basis the functional visual field size of a patient was defined as the size of the artificially narrowed visual field of the normal subject that required the same recognition time as that of the patient. The functional visual field of patients could be correlated with the area of the perimetric field with the V/4 target of Goldmann's projection perimeter. The concept of the functional visual field was found to be useful to express the patients' capability for pattern perception.

Adult↗