Biomedical subjects

N Yokota

Publications and source records attributed to N Yokota.

At least 91 records · Page 5Linked to original sources

PubMed1995

Molecular forms of human brain natriuretic peptide (BNP) in plasma of patients on hemodialysis (HD).

Plasma brain natriuretic peptide (BNP) levels have been reported to increase in patients with heart failure and end-stage renal disease (ESRD); however, little is known about molecular forms of plasma BNP that increase in these diseases. In the present study, we analyzed the molecular forms of plasma BNP in ESRD patients of both before (pre-) and after (post-) hemodialysis (HD) state. The plasma extract was analyzed by gel filtration on a TSK-GEL G2000 SW column followed by a RIA for both BNP and atrial natriuretic peptide (ANP). In the pre-HD patients, a 14- to 2300-fold increase in plasma level of immunoreactive (ir-) BNP was observed when compared to normal controls. A ratio of BNP-32 to g-BNP (pro BNP) in plasma from the patients was much larger than that in plasma from normal subjects, indicating that the high plasma level of ir-BNP level in the patients on HD largely results from a marked increase in BNP-32. HD significantly (P < 0.01) lowered the plasma levels of both BNP-32 and g-BNP with a greater reduction in BNP-32 than in g-BNP. Whereas, a-ANP was a main molecular form of plasma ANP in both pre- and post-HD plasma. These results suggest that plasma BNP-32 plays an important role in the sodium-fluid balance and that secretion and metabolism of BNP may differ from those of ANP in the HD patients.

Adult↗

PubMed1995

[Antibacterial activities of cefmenoxime against recent fresh clinical isolates from patients in sinusitis].

In order to evaluate antimicrobial activity of cefmenoxime (CMX), minimum inhibitory concentrations (MICs) of CMX and control drugs were determined against clinical isolates from patients of sinusitis that were obtained in our laboratory from October of 1993 to March of 1994. The results are summarized as follows; 1. CMX showed strong antimicrobial activities against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella subgenus Branhamella catarrhalis that were 3 major aerobic bacteria from sinusitis. Antimicrobial activities of CMX against benzylpenicillin (PCG)-insensitive S. pneumoniae (PISP) and PCG-resistant S. pneumoniae (PRSP) were stronger than those of ampicillin (ABPC), and these strong activities suggested that CMX might have strong antimicrobial activities against beta-lactamase producing H. influenzae and M. (B.) catarrhalis. 2. Antimicrobial activities of CMX against microaerophiles, Streptococcus constellatus, Streptococcus intermedius and Gemella morbillorum and against Peptostreptococcus spp., from chronic sinusitis and odontogenic maxillary sinusitis, were stronger than those of most of the control drugs. 3. The MIC90's of CMX against isolates from patients of sinusitis were < or = 0.025-0.39 micrograms/ml. These values were lower than transitional concentrations in mucous membrane of maxillary sinus obtained when "1% CMX nasal solution" was used with nebulizer. It appears likely that sufficient concentrations exceeding MICs against main organisms would be obtained by nebulizer treatment using CMX nasal solution.

Cefmenoxime↗

PubMed1995

[Detection of bacteria in urine using dip-slides (1). Possible occurrence of false-negative results when dip-slides are used for urine containing antibacterial agents].

Dip-slides are used as semiquantitative microbial sampling devices that are simple to use in routine testing of urine to detect the presence of bacteria, and are recommended for use in "Standard evaluation of drug efficacy in UTI". Bacterial growth on currently available dip-slides, however, may conceivably be influenced by the presence of antibacterial agents in urine. We studied clinical performance of, and effects of antibacterial agents on, such dip-slides, using two types of dip-slides, URICULTE and DIASLIDE, both of which are newly developed urine culture devices. The quantitative conventional culture method was also used as the control. 1. When single species of bacteria are present in urine specimens of patients, results obtained using URICULTE and DIASLIDE agreed very well, and they, in turn agreed well with results obtained using the quantitative, conventional culture method, also. 2. When urine specimens were spiked with Gram-negative rods and Gram-positive cocci together, URICULTE fail to provide quantitative results because colonies were not well separated and confluent growth often resulted because of a large sample volume this device employs. DIASLIDE which used a smaller amount of sample, on the other hand, provided quantitative results with adequate separation of colonies. 3. When three antibacterial agents were added to urine specimens that were spiked with bacteria, DIASLIDE produced significantly higher numbers of colonies than URICULTE. The difference probably are due to the difference in volumes of specimens used in the two devices, the former device employs approximately 1/100 as much volume of specimen as the latter.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗

PubMed1995

[Antibacterial activities of fosfomycin against recent clinical isolates from patients of otitis media and otitis externa].

Clinical isolates from patients with otitis media and/or otitis externa were collected at otorhinology clinics nationwide and sent to us during 1989, 1991 and 1993. Minimum inhibitory concentrations (MICs) of fosfomycin (FOM) and of reference drugs against these strains were determined to investigate year-to-year antibacterial activity of FOM. A comparative analysis of the results revealed trends described below. 1. The MIC90 of FOM against Staphylococcus aureus subsp. aureus increased 4 times by 1993 as compared to those measured for strains isolated in 1984 and 1985, when FOM for otic use was under development. This was thought to be due to the recent increase in the detection frequency of methicillin-resistant S. aureus (MRSA) which is also resistant to FOM. 2. No annual changes were seen for MIC distribution of FOM against Proteus group and Pseudomonas aeruginosa. 3. Since there was no large annual change in the antibacterial activity of FOM against recent clinical isolates obtained from patients with otitis media and/or otitis externa, FOM may be considered as one of the useful drugs even now, in the mid-1990's.

Drug Resistance, Microbial↗

PubMed1995

[Beta-lactamase production of clinically isolated bacteria].

We examined beta-lactamase productions by clinically isolated strains of bacteria. The results were as follows; 1. It appears that beta-lactamases produced by strains of five species of Staphylococcus spp. are mostly penicillinase (90%). Source of beta-lactamase producing strains of Haemophilus influenzae (23%) and all of Moraxella subgenus Branhamella catarrhalis: strains (100%) are "High & Low producer" strains. 2. A large proportion of beta-lactamase producing strains of Enterobacteriaceae and Bacteroides fragilis group appeared to be "High producer" 3. beta-lactamase producing abilities are different among glucose non-fermentative Gram-negative rods. It appears that some of the strains appeared to be "High producers".

Bacteria↗

PubMed1995

[Antimicrobial activities of sulbactam/ampicillin against clinically isolated microbial strains].

Antimicrobial activities were examined for sulbactam/ampicillin (SBT/ABPC) against clinically isolated microbial strains in 1987, 1990, 1994. Besides, the beta-lactamase productivity and MICs of these strains were measured, and the following conclusions were obtained. 1. The ratio of beta-lactamase producing strains were 90% of methicillin (DMPPC)-susceptible Staphylococcus aureus subsp. aureus (MSSA), about 80% of DMPPC-resistant S. aureus (MRSA), 100% of Escherichia coli, Klebsiella pneumoniae subsp. pneumoniae and Proteus mirabilis, 95% of Moraxella subgenus Branhamella catarrhalis and 15-20% of Haemophilus influenzae. Several kinds of beta-lactamase productivity were observed. 2. Antimicrobial activities of SBT/ABPC against beta-lactamase producing strains of MSSA, M. (B.) catarrhalis, H. influenzae, and almost all of Enterobacteriaceae were stronger than those of ampicillin (ABPC) and piperacillin (PIPC), but antimicrobial activities of SBT/ABPC were weak against MRSA and cephems (CEPs)-resistant strains detected in some of Enterobacteriaceae. 3. It appeared that benzylpenicillin (PCG)-insensitive Streptococcus pneumoniae (PISP) or PCG-resistant S. pneumoniae (PRSP) and CEPs-resistant Escherichia coli increased year by year. 4. Antimicrobial activities of SBT/ABPC were strong against Streptococcus pyogenes, S. pneumoniae, M. (B.) catarrhalis and H. influenzae including beta-lactamase producing strains. Additionally, beta-lactamase inhibiting effect of SBT was observed against beta-lactamase produced by S. aureus and K. pneumoniae which demonstrate indirect pathogenicity. Thus, SBT/ABPC is an injectable antibiotic that is expected to demonstrate clinical usefulness, especially as the first line drug for the respiratory tract infections that are community-acquired.

Ampicillin↗

PubMed1995

[Antimicrobial activities of piperacillin against fresh clinically isolated strains].

In order to evaluate the antimicrobial activity of piperacillin (PIPC), along with control agents, minimum inhibitory concentrations (MIC's) were determined against fresh clinically isolated strains from January to June, 1994. 1. The MIC70's of PIPC against major strains were approximately equal to those reported in the mid 1980s. 2. Strains for the study were supplied in approximately equal numbers from community-acquired hospitals and general hospitals. The ratios of bacteria resistant to beta-lactams including PIPC were low in the former group and high in the latter. 3. "New types of beta-lactam-resistant strains" which did not exist in mid 1980s but found at this time included benzylpenicillin (PCG)-insensitive Streptococcus pneumoniae, PCG-resistant S. pneumoniae, cephems-resistant Escherichia coli and beta-lactamase producing Prevotella spp. These bacteria were also found among strains obtained from community-acquired hospitals.

Bacteria↗

PubMed1995

[Mechanical ventilation and long-term respiratory care in the intensive care unit of a general hospital].

We studied the need for mechanical ventilation in 265 patients with respiratory failure who came to our medical ICU over the past 3 years. The time required for weaning from mechanical ventilation and the percentage of patients who needed oxygen therapy or mechanical ventilation at home after their condition was no longer acute were also studied. Of the patients treated in the medical ICU, 143 (54%) required mechanical ventilation; 104 (39%) had acute respiratory failure and the others had acute exacerbations of chronic respiratory failure. Some causes of acute respiratory failure were aspiration pneumonia, bronchial asthma, and drug use. Three-fourths of those with chronic respiratory failure had pulmonary emphysema, sequela of pulmonary tuberculosis, or idiopathic interstitial pneumonia. In patients with chronic respiratory failure, success in weaning could be predicted from the respiratory index (PaO2/FIO2), the serum albumin level, and the length of time that they were ventilated with more than 60% oxygen. Thirteen patients with chronic respiratory failure died while receiving mechanical ventilation. Of those who survived, 11 underwent tracheostomies, and 4 of those 11 were mechanically ventilated at home with portable devices. Ten other survivors received home oxygen therapy. Chest physicians bear the greatest responsibility for managing mechanical ventilation in medical emergencies. Moreover, the prognosis for patients with chronic respiratory failure can be improved with a long-term program for respiratory care that includes home mechanical ventilation and home oxygen therapy.

Adult↗

PubMed1994

Effect of chronic tryptophan depletion on the circadian rhythm of wheel-running activity in rats.

The effect of chronic treatment with a tryptophan (TRP)-free diet on the free-running circadian wheel-running rhythm and the central serotonergic system was investigated in blinded male rats. The long-term TRP-free diet did not change periods of activity, but disordered their patterns. This seemed to be due to masking, entrainment, enhancement of the morning activity, and obscuring of the activity onset as well as appearance of some periodic activities within the subjective night. A long-term TRP-fre diet decreased the concentration of TRP, 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in all brain regions tested: frontal cortex, hippocampus, thalamus, hypothalamus, midbrain, and pons. Density of 5-HT1A receptor binding was significantly decreased in the frontal cortex and hypothalamus, whereas no significant change was observed in the density of 5-HT2 receptor binding in all regions. These results suggest that the period of primary circadian pacemaker is not affected, but its oscillation, as well as the coupling strength between the primary and secondary pacemakers, is weakened by the dysfunction of the serotonergic system caused by chronic TRP depletion.

Animals↗

PubMed1994

Plasma concentration of human brain natriuretic peptide in patients on hemodialysis.

The plasma concentration of immunoreactive human brain natriuretic peptide (ir-BNP) was measured in 40 patients on hemodialysis (HD) and in 12 healthy subjects. Immunoreactive human atrial natriuretic peptide (ir-ANP) was also measured. The mean (+/- SE) plasma ir-BNP concentration in the patients before HD (18.4 +/- 3.4 fmol/mL) was markedly higher than that in the control group (0.39 +/- 0.08 fmol/mL). The plasma ir-BNP level was significantly decreased by HD from 18.4 +/- 3.4 fmol/mL to 10.5 +/- 2.2 fmol/mL (P < 0.001), but the latter value was still higher than the upper limit of the normal range for our laboratory. There were significant correlations between the plasma ir-ANP level and the mean blood pressure before HD (P < 0.05) and between the HD-induced changes in plasma ir-ANP level and mean blood pressure (P < 0.001). These correlations were not observed between the plasma ir-BNP level and mean blood pressure. The plasma ir-BNP level correlated with the cardiothoracic ratio and this correlation was closer to that between the plasma ir-ANP level and cardiothoracic ratio. Ultrasound echocardiographic studies in 13 patients revealed that the pre-HD state of high cardiac output was correlated by HD in association with decreases in plasma ir-BNP and ir-ANP levels. Correlations were observed between the pre-HD ir-ANP level and the interventricular septal thickness index (r = 0.68, P < 0.05) and between the change in ir-BNP level and that in left atrial diameter (r = 0.806, P < 0.001). In conclusion, BNP levels were high in HD patients compared with the control subjects and were decreased during HD. In addition, BNP and ANP levels correlated with several parameters of volume change and cardiac status.

Atrial Natriuretic Factor↗

PubMed1994

A novel zinc finger protein, zic, is involved in neurogenesis, especially in the cell lineage of cerebellar granule cells.

To clarify the mechanism of cerebellar development, we have cloned a gene, named zic, encoding a zinc finger protein that is expressed abundantly in granule cells throughout development of the cerebellum. zic has a significant homology to the zinc finger domain of the Caenorhabditis elegans tra1 gene, the Drosophila cubitus interruptus Dominant gene, and the human GLI oncogene. An in situ hybridization study revealed that zic showed a restricted expression pattern in the granule cells and their putative precursor cells. It is also expressed at an early embryonic stage in the dorsal half of the neural tube. The expression pattern and nuclear localization were confirmed by immunohistochemical study. Furthermore, the bacterially expressed zic protein containing the zinc finger domains bound to the GLI-binding sequence. These findings suggest that zic is one of a number of nuclear factors involved in both differentiation in early development and maintenance of properties of the cerebellar granule cells.

Amino Acid Sequence↗

PubMed1994

Atrial natriuretic factor significantly contributes to the mineralocorticoid escape phenomenon. Evidence for a guanylate cyclase-mediated pathway.

The mechanism underlying the mineralocorticoid escape phenomenon remains unknown. To assess the possible contribution of natriuretic peptides to mineralocorticoid escape, rats were injected with 5 mg deoxycorticosterone acetate for 3 d. Plasma atrial natriuretic factor (ANF) rose to twice basal levels and atrial ANF content decreased significantly by 24 h of treatment. This coincided with renal escape and with a significant increase in urinary cGMP excretion. Plasma ANF remained elevated and atrial ANF content continued to decline by 48 and 72 h while atrial ANF mRNA levels increased significantly only at 72 h. Plasma brain natriuretic peptide did not increase during escape although atrial brain natriuretic peptide mRNA levels increased significantly. Chronically administered HS-142-1 (HS), a specific antagonist of the guanylate cyclase-coupled natriuretic peptide receptors, significantly and dose-dependently impaired the escape phenomenon. The highest dose of HS completely suppressed the increase in urinary cGMP. Despite the continued suppression, partial escape was observed by the end of the observation period. HS alone influenced neither plasma nor tissue or urine parameters. These findings show that despite activation of atrial ANF, blockade of the guanylate cyclase-coupled natriuretic peptide receptors impairs the ability of the kidney to escape the Na+ retaining effect of excess mineralocorticoid in a dose-dependent fashion. Later-acting, unknown mechanisms eventually come into play to mediate the escape phenomenon through a guanylate cyclase-independent pathway. Therefore, ANF of cardiac origin appears to be a major factor initiating mineralocorticoid escape through a guanylate cyclase-dependent pathway.

Animals↗

PubMed1994

[Antimicrobial activities of cefditoren against clinical isolates obtained from outpatients].

To examine the antimicrobial activity of cefditoren (CDTR) against strains clinically isolated from outpatients at this hospital from November, 1993 to February, 1994, the minimum inhibitory concentrations (MICs) were determined including those of the control drugs. The results were as follows: 1. CDTR showed strong antimicrobial activities against Staphylococcus aureus subsp. aureus, Streptococcus pyogenes and Streptococcus pneumoniae. The MICs of CDTR against benzylpenicillin-insensitive or -resistant S. pneumoniae distributed in the lowest concentration range even compared to those of the control drugs. 2. CDTR showed strong antimicrobial activities against Haemophilus influenzae, Moraxella subgenus Branhamella catarrhalis, Escherichia coli, and Klebsiella spp. The MIC of CDTR against CEPs-resistant E. coli was lower than those of most control drugs. 3. Since the microbes described above the major pathogens for the community-acquired infections, CDTR will be effective against infectious diseases transmitted at outpatient visits.

Bacteria↗

PubMed1994

[Antibacterial activities of new quinolones against fresh clinical isolates].

In order to investigate antibacterial activities of new quinolones (NQs) against a number of clinical isolates obtained in our laboratory during a period from February, 1993 to January, 1994, minimum inhibitory concentrations (MICs) were determined using most of the NQs available in the market as of December, 1993. The obtained results are summarized as follows: 1. Noticeable differences were observed among the antibacterial activities of 8 different NQs tested against Gram-positive bacteria, i.e., there were large differences in their MIC distributions. Some differences were also observed among different NQs in ratios of NQ-resistant strains among Staphylococcus spp. From these results, it seems necessary to further study tolerance mechanisms of these Gram-positive bacteria toward different NQs and also to examine possible differences in antibacterial activities among different NQs against Gram-positive bacteria in clinical settings. 2. MIC distributions against Gram-negative bacteria were also different among the 8 NQs tested. Though elevated MICs were observed against NQ-resistant Gram-negative bacteria in many cases, and somewhat higher, though not exceedingly high, MIC values than those against NQ-sensitive bacteria were found in other cases, patterns of MIC values against different NQ-resistant Gram-negative bacteria were similar for all of the 8 NQs tested. This may explain the fact that most of NQ-resistant Gram-negative bacteria showed similar resistant patterns to the 8 NQs tested. 3. Among the NQ-resistant bacteria, were found Haemophilus influenzae and Neisseria gonorrhoeae strains. Ratios of resistant strains were approximately 10% or lower for the former and approximately 20% for the latter. 4. With MICs of ampicillin and cefaclor used as control, it appears that benzylpenicillin (PCG)-insensitive or PCG-resistant Streptococcus pneumoniae (PISP or PRSP) and CEPs-resistant Escherichia coli are increasing.

4-Quinolones↗

PubMed1994

[Antibacterial activities of cefetamet against clinically isolated strains from community acquired respiratory tract infections (II)].

Antibacterial activities of cefetamet (CEMT) against clinically isolated strains from patients with community acquired respiratory tract infections were compared to those of other oral beta-lactam antibiotics in the period from January to March 1994. The following results were obtained. 1. CEMT showed strong antibacterial activities against three major pathogens causing community acquired respiratory tract infections, Streptococcus pyogenes, Streptococcus pneumoniae, and Haemophilus influenzae. However, antibacterial activities of CEMT against benzylpenicillin (PCG)-insensitive S. pneumoniae (PISP) and PCG-resistant S. pneumoniae (PRSP) were slightly weaker than of those of some the reference antibiotics. 2. No MIC value changes of CEMT were observed from year to year against Moraxella subgenus Branhamella catarrhalis and Klebsiella pneumoniae.

Bacteria↗

PubMed1994

[Antibacterial activities of isepamicin against fresh clinical isolates of gram-negative bacilli].

To investigate antibacterial activities of isepamicin (ISP), MICs of ISP as well as other aminoglycosides (AGs) were determined against many strains of Gram-negative bacilli that were clinically isolated in 1993. 1. No ISP-resistant strains were observed among isolates of Escherichia coli, Citrobacter diversus, Klebsiella spp., Enterobacter spp. or Proteus mirabilis. 2. ISP-resistant strains were observed among isolates of Citrobacter freundii, Serratia spp., Proteus vulgaris, Morganella morganii, Providencia spp. and Pseudomonas aeruginosa. The frequency of resistant strains in each species, however, was lower for ISP than other AGs. 3. When MIC90s were compared, antibacterial activities of ISP determined in this study were quite similar to those determined during the drug's development period (1980's) in Japan, suggesting no increase in the number of ISP-resistant strains over the years. 4. The number of clinically isolated Gram-negative bacilli resistant to multiple drugs are increasing in from year to year Japan. Our results in this study suggest that antibacterial activities of ISP may be potent enough against such Gram-negative bacilli resistant to multiple drugs.

Drug Resistance, Microbial↗

PubMed1994

[Antimicrobial activities of ciprofloxacin against recently obtained clinical isolates].

In order to evaluate antimicrobial activity of ciprofloxacin (CPFX), minimum inhibitory concentrations (MICs) of CPFX and other drugs were determined against clinical isolates that were obtained in our laboratory from January to December of 1991, and of 1993. The results are summarized as follows: 1. CPFX-resistant strains were on the increase in various strains, compared to those in the early 1980s. However, many of CPFX-resistant strains were multi-drug resistant including beta-lactams. In addition, they showed cross resistance to other fluoroquinolone agents. 2. MIC distribution of other drugs suggested that there were increased frequencies of benzylpenicillin (PCG)-insensitive Streptococcus pneumoniae (PISP) and CEPs-resistant Escherichia coli. However, MIC distribution of CPFX to these resistant strains were in a relatively low range. 3. When isolates of 1991 were compared to those of 1993, we confirmed that CPFX-resistant strains decreased among certain bacteria such as Staphylococcus aureus. Also we confirmed that fewer CPFX-resistant strains were found among bacteria that may be highly related to infections encountered in daily medical care.

Bacteria↗

PubMed1994

[Antimicrobial activities of fosfomycin against Streptococcus pneumoniae and Haemophilus influenzae recently observed in sinusitis patient].

In order to examine antimicrobial activities of fosfomycin (FOM), the minimum inhibitory concentrations (MICs) of FOM and those of control drugs were determined against Streptococcus pneumoniae and Haemophilus influenzae isolated from sinusitis patients from September to November, 1993, and the following results were obtained. 1. Among 50 S. pneumoniae strains tested, there were 10 strains (20.0%) of benzylpenicillin (PCG)-insensitive S. pneumoniae (PISP) and 2 strains (4.0%) of PCG-resistant S. pneumoniae (PRSP); but the MIC distributions of FOM among the PISPs and the PRSPs were almost identical to those among the PCG-susceptible S. pneumoniae (PSSP). 2. There were 12 strains (24.0%) of beta-lactamase producing strains among 50 strains of H. influenzae tested, but the FOM's MIC distribution among these strains was almost identical to that among beta-lactamase non-producing strains. 3. The results obtained on the MIC90s of FOM against S. pneumoniae and H. influenzae suggest that the nebulization treatment with FOM nasal preparation satisfies the condition "above the MIC".

Drug Resistance, Microbial↗