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Biomedical subjects

A Nakamura

Publications and source records attributed to A Nakamura.

At least 163 records · Page 9Linked to original sources
PubMed2000

Cardiovascular and metabolic responses of hypertensive and normotensive rats to one week of cold exposure.

Challenges to energy homeostasis, such as cold exposure, can have consequences for both metabolic and cardiovascular functioning. We hypothesized that 1-wk cold exposure (4 degrees C) would produce concurrent increases in metabolic rate (VO(2); indirect calorimetry), heart rate (HR), and mean arterial blood pressure (MAP) measured by telemetry. In the initial hours of change in ambient temperature (T(a)), both spontaneously hypertensive rats (SHRs) and normotensive Sprague-Dawley rats showed rapid increases (in cold) or decreases (in rewarming) of VO(2), HR, and MAP, although the initial changes in MAP and HR were more exaggerated in SHRs. Throughout cold exposure, HR, VO(2), food intake, and locomotor activity remained elevated but MAP decreased in both strains, particularly in the SHR. During rewarming, all measures normalized quickly in both strains except MAP, which fell below baseline (hypotension) for the first few days. The results indicate that variations of T(a) produce rapid changes in a suite of cardiovascular and behavioral responses that have many similarities in hypertensive and normotensive strains of rats. The findings are consistent with the general concept that the cardiovascular responses to cold exposure in rats are closely related to and perhaps a secondary consequence of the mechanisms responsible for increasing heat production.

Acclimatization↗
PubMed2000

Effects of hemoglobin on pulmonary arterial pressure and pulmonary vascular resistance in patients with chronic emphysema.

BACKGROUND: The increase in viscosity caused by secondary polycythemia is thought to be one of the major causes of pulmonary hypertension secondary to chronic emphysema. However, very few clinical studies considered the relation between pulmonary hypertension and polycythemia in the case of chronic obstructive pulmonary disease. OBJECTIVE: The purpose of this study is to elucidate the relative contribution of an increase in hemoglobin level (Hb) to mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR). METHODS: We retrospectively investigated 41 patients with chronic emphysema who had undergone a right heart catheterization. Multiple-regression analysis and F test were performed to investigate both direct effects of Hb and PaO(2) as independent variables on mPAP and PVR as dependent variables. RESULTS: Significant correlations were found between PaO(2) and mPAP (or PVR), or Hb and mPAP (or PVR), indicating that both Hb and PaO(2) are contributory to mPAP and PVR. The F test demonstrated that Hb and PaO(2) could directly affect the level of either mPAP or PVR. CONCLUSIONS: It was concluded that Hb had a direct effect on mPAP and PVR, independently of hypoxia in patients with chronic emphysema.

Aged↗
PubMed2000

Activation of osteoblast-like MC3T3-E1 cell responses by poly(lactide).

This study examined the osteoblast-like MC3T3-E1 cell responses to poly(DL-lactide) (PDLLA) and poly(L-lactide) (PLLA) with different weight average molecular weight (M.W.). Colony formation of MC3T3-E1 cells on the PLLA with M.W. 270000 or 1370000 was slightly lower than that on glass. The protein, DNA and hydroxyproline (HYP) content and alkaline phosphatase (ALP) activity for cells cultured on the PLLA (M.W. 270000 or 1370000) for 14 d were almost similar to those on glass. In contrast, the ALP activity of the cells cultured on low M.W. PLLA (M.W. 20000) increased. Osteoblast differentiation was stimulated by low M.W. PLLA but not by high M.W. PLLA. The addition of low M.W. PDLLA (M.W. 5000 or 10000), L-lactide or L-lactic acid into culture increased the protein, DNA and HYP content and ALP activity for cells at 100 microg/ml. Compared with four chemicals, PDLLA (M.W. 10000) had the strongest simulation effect on the cell. The release of L-lactic acid from PLLA and PDLLA into aqueous solution during incubation only slightly affected cell activity. In a cell-free condition, in the presence of PDLLA, the ALP activity was maintained without inactivation, even after 24 h incubation. Such a phenomenon was not seen with L-lactide and L-lactic acid. This may be a reason why PDLLA has a stronger effect on osteoblast differentiation relative to L-lactic acid. These results suggested that increased osteoblast differentiation was induced by low M.W. PDLLA and PLLA, and these may be used as a effective material in the field of orthopedic and drug delivery systems for the treatment of bone diseases.

Alkaline Phosphatase↗
PubMed2000

Synthesis of 3-epi-6,7-dideoxyxestobergsterol A.

3-Epi-6,7-dideoxyxestobergsterol A (2), an analogue of xestobergsterol A, has been synthesized from dehydroepiandrosterone (3) in 15 steps. The key synthetic intermediate, 15beta,16alpha-dioxypregn-17(20)E-ene derivative 8, was prepared from the corresponding 15beta,16beta-epoxide 6 by treating with acetic acid and titanium tetraisopropoxide. The 23-oxo side chain was constructed stereoselectively by orthoester Claisen rearrangement of 8 followed by introduction of an isobutyl group. Basic treatment of the 15,23-diketone 12 followed by deprotection gave the title compound 2.

Animals↗
PubMed2000

[Determination of antimicrobial, 10,10'-oxybis-10H-phenoxarsine, in artificial leather used for the seat of chairs].

Recently, a case of patients with allergic contact dermatitis caused by the poly (vinyl chloride) (PVC) seat, containing 10,10'-oxybis-10H-phenoxarsine (OBPA), of a chair was reported. OBPA was developed as an antimicrobial for plastics such as PVC and polyurethane, and it has been widely used in artificial leather for the seats of chairs and sofas. To identify causative chemicals for allergic contact dermatitis, a combination of patch testing in the patients and chemical analysis of causative products is valuable. However, no analytical method and data of OBPA in commercial products was reported. In this study, a method for the determination of OBPA in the artificial leather (PVV base) was developed. OBPA was extracted from PVC samples with methanol. The extract was loaded on an aluminum oxide column, and washed with diethyl ether:hexane, and eluted with ethanol:hexane. The eluate was evaporated, dissolved in methanol and injected to a HPLC equipped an ODS column and an UV detector (detection wavelength 300 nm). OBPA standard crystal was isolated from commercial agents containing OBPA. The calibration curve for OBPA was linear in the range of 0.1-100 micrograms/ml. The minimum detection and determination concentrations of OBPA in samples were 0.07 and 0.25 microgram/g. By this method, eight PVC sheets for the seat of a chair were analyzed. In two PVC sheets, 52.7 and 84.9 micrograms/g of OBPA were detected. In the PVC product that caused contact dermatitis, OBPA was not found.

Arsenicals↗
PubMed2000

Ultraviolet spectrometric determination of neutral monosaccharides by HPLC with ethanolamine.

The reaction between ethanolamine and sugars in a borate solution gave intense UV absorption at 310 nm. By adding ethanolamine in the mobile phase, simple and sensitive ion-exchange HPLC of sugar-borate complexes was achieved. This method can be used to measure as little as 100 pmole of seven monosaccharides from pectic polysaccharides.

Chromatography, High Pressure Liquid↗
PubMed2000

Compilation and characterization of histidine-containing phosphotransmitters implicated in His-to-Asp phosphorelay in plants: AHP signal transducers of Arabidopsis thaliana.

Histidine (His)-to-Aspartate (Asp) phosphorelay signal transduction systems are generally made up of a "sensor histidine (His)-kinase", a "response regulator", and a "histidine-containing phosphotransmitter (HPt)". In the higher plant, Arabidopsis thaliana, results from recent intensive studies suggested that the His-to-Asp phosphorelay mechanism is at least partly responsible for propagation of environmental stimuli, such as phytohormones (e.g. ethylene and cytokinin). Here we compiled the members of the HPt family of phosphotransmitters in Arabidopsis thaliana (AHP-series, Arabidopsis HPt phosphotransmitters), based on both database and experimental analyses, in order to provide a comprehensive basis at the molecular level for understanding the function of the AHP phosphotransmitters that are implicated in the His-to-Asp phosphorelay of higher plants.

Amino Acid Sequence↗
PubMed2000

Cessation of cerebral hemorrhage recurrence associated with corticosteroid treatment in a patient with cerebral amyloid angiopathy.

We report the case of a 65 year old female patient with biopsy-proven cerebral amyloid angiopathy (CAA). She experienced intracerebral hemorrhages 4 times during 23 days but these serious strokes did not recur after corticosteroid therapy was started and her condition greatly improved. Since high titers of antinuclear antibodies and elevated erythrocyte sedimentation rate were found in her serum, she may have an inflammatory disorder involving amyloid-laden cerebral vessels. This is the first report showing the usefulness ofcorticosteroid for the treatment of CAA-related cerebral hemorrhages. Additionally, the concentrations of Abeta40 and Abeta42 in the CSF of this patient decreased rapidly after the use of corticosteroid, and ultimately fell far below normal values.

Adrenal Cortex Hormones↗
PubMed2000

Macrolide esterase-producing Escherichia coli clinically isolated in Japan.

Current Japanese clinical practice involves the usage of large amounts of new macrolides such as clarithromycin and roxithromycin for the treatment of diffuse panbronchiolitis, Helicobacter pylori and Mycobacterium avium complex infections. In this study, the phenotypes, genotypes, and macrolide resistance mechanisms of macrolide-inactivating Escherichia coli recovered in Japan from 1996 to 1997, were investigated. The isolation rate of erythromycin A highly-resistant E. coli (MIC > or = 1,600 microg/ml) in Japan slightly increased from 0.5% in 1986 to 1.2% in 1997. In six macrolide-resistant strains, recovered from the strains collected for this study during 1996 to 1997, the inactivation of macrolide could be detected with or without added ATP in the assay system. The appearance of erythromycin A-inactivating enzyme independent of ATP was novel from Japanese isolates, and the 1H NMR spectra of oleandomycin hydrolyzed by the three ATP-independent isolates were examined. It was clearly shown that the lactone ring at the position of C-13 was cleaved as 13-H signal in aglycon of oleandomycin upper shifted. These results suggested the first detection of macrolide-lactone ring-hydrolase from clinical isolates in Japan. These results suggested the first detection of an ATP-independent macrolide-hydrolyzing enzyme from Japanese clinical isolates. Substrate specificity of the macrolide-hydrolyzing enzyme was determined with twelve macrolides including the newer members of this group and it was found that not only erythromycin A but also the new macrolides, such as clarithromycin, roxithromycin, and azithromycin were inactivated. The NMR data, broad spectrum of activity, and independence of co-enzyme supported our naming of the enzyme as a macrolide esterase. PCR methodology was employed to detect an ereB-like gene from the 3 isolates producing macrolide esterase, and one of these was subsequently shown to contain both ereB-like and ermB-like genes. It was also clearly shown that the other three isolates, which inactivated macrolide in the presence of ATP, had an mphA-like gene.

Anti-Bacterial Agents↗
PubMed2000

[The resistance of recent clinical isolates against isepamycin, other aminoglycosides and injectable beta-lactams].

Clinical isolates collected from clinical facilities across Japan in 1998 were tested against five aminoglycosides and three beta-lactams. The resistance of 50 strains each of methicillin sensitive Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, Citrobacter freundii, Klebsiella pneumoniae, Enterobacter sp., Serratia sp., Pseudomonas aeruginosa and Proteus sp. (P. mirabilis 25 strains and P. vulgaris 25 strains) to the aminoglycosides isepamicin (ISP), amikacin (AMK), gentamicin, tobramycin and dibekacin, and to the beta-lactams imipenem, ceftazidime and piperacillin (all three known to be effective against P. aeruginosa) were investigated using a micro liquid dilution method with the following results: 1. ISP was effective against all strains except for 14% of MRSA, 2% of Proteus sp., and 4% of P. aeruginosa. 2. Six strains of MRSA were resistant to all eight drugs; however, in these cases ISP exhibited a relatively low minimum inhibitory concentration (MIC) compared to the other compounds. 3. Four strains of MRSA were resistant to all drugs except ISP. MRSA was the only isolate to demonstrate a resistance to seven or more drugs. 4. Twenty-one strains of MRSA and 1 strain of P. aeruginosa were resistant to six drugs; however, all of these were susceptible to both ISP and AMK. 5. Against all strains tested, ISP generally exhibited a lower MIC compared to AMK. These results suggest that, even ten years after its entering the market, ISP is still an aminoglycoside having a high anti-bacterial activity against a wide range of clinical isolates.

Amikacin↗
PubMed2000

[The procedures for detection of penicillin-resistant Streptococcus pneumoniae and the epidemiology].

Penicillin-resistant Streptococcus pneumoniae was first described in South Africa in 1977 and soon afterward was reported in other countries and in Japan. According to NCCLS standards for antimicrobial susceptibility tests, in vitro activity of S. pneumoniae is the best procedure using the minimum inhibitory concentration method. Benzylpenicillin, cefotaxime or ceftriaxone, and meropenem should be tested by a reliable MIC method and the susceptibility should be reported in the case isolated from blood and/or cerebrospinal fluid. Using the oxacillin test, it is difficult to distinguish penicillin-resistant from intermediate strains or sometimes susceptible strains.

Microbial Sensitivity Tests↗
PubMed2000

[Detection methods for drug-resistant bacteria in routine examination--BLNAR].

The characteristics of resistance, trend of prevalence and current status of beta-lactamase-negative, ampicillin-intermediate or -resistant(BLNAR) strains of Haemophilus influenzae are summarized by our retrospectively analyzed data. The mechanism of this type of ampicillin-resistance is due to altered penicillin-binding proteins(PBPs). Standardized susceptibility tests may differentiate ampicillin-resistant, beta-lactamase-producing strains from beta-lactamase-negative, ampicillin-susceptible strains(BLNAS), but may not differentiate some strains of BLNAR from those of BLNAS. In the cases of serious infections, such as meningitis due to H. influenzae both beta-lactamase activity and ampicillin susceptibility should be confirmed by the MIC procedure.

Ampicillin Resistance↗
PubMed2000

[An autopsy case of primary cerebellar-pontine angle epidermoid carcinoma].

A 65-year-old man developed right facial palsy and six months later experienced sudden unconsciousness and right hemiplegia. On admission he had severe nuchal rigidity, decreased visual acuity, and a hearing disturbance. A CT scan and angiography failed to reveal any lesions in the brain, but CSF cytology showed undifferentiated malignant cells with a high level of neuron-specific enolase. A postcontrast CT scan and MRI demonstrated diffuse meningeal enhancement and a faintly rim-enhanced cystic lesion at the cerebellopontine angle. The patient died four months after admission, and postmortem examination revealed meningeal dissemination of squamous cell carcinoma, probably arising from an epidermoid cyst at the cerebellopontine angle. Microscopic examination revealed squamous epithelial debris and a foreign body reaction in portions of the cyst wall and in the surrounding subarachnoid space near the base of the cyst. Rim enhancement of the cyst on MRI and the microscopic findings indicated that the recurrent headaches may have been the result of chemical aseptic meningitis caused by spontaneous leakage of the cyst's contents.

Aged↗
PubMed2000

Linkage of autosomal recessive hereditary spastic paraplegia with mental impairment and thin corpus callosum to chromosome 15A13-15.

To date, three loci for autosomal recessive hereditary spastic paraplegia (ARHSP) linked to chromosomes 8p12-q13, 16qter, and 15q13-15 have been characterized. We have clinically characterized 13 Japanese ARHSP families and performed genetic linkage analyses. All 13 families were classified as having the "complicated" form, which manifests with mental impairment and thin corpus callosum. Linkage to the 8p12-q13 and 16qter loci was excluded, although 10 of the 13 families showed marker data consistent with linkage to the 15q13-15 locus. The multipoint LOD score of the 10 families linked to chromosome 15 was above 9.00 in the 3-centimorgan segment flanked by D15S994 and D15S659, with a maximum multipoint LOD score of 9.68 at a position 1.2 centimorgans telomeric from D15S994 to D15S659. We have shown that ARHSP with thin corpus callosum, a subtype of recessive spastic paraplegia, maps to chromosome 15q13-15.

Adolescent↗
PubMed2000

A sandwich enzyme-linked immunosorbent assay for ABO blood typing of semen by using anti-p 84 monoclonal antibody as a marker of blood group substance in semen.

A blood group substance (BGS), a protein with ABH antigenic activity, was isolated from human seminal plasma and designated as p 84 (Sato, 1995). We have developed a method for determining the ABO blood type of semen by performing a sandwich enzyme-linked immunosorbent assay (ELISA) in which p 84 is captured with an anti-p 84 monoclonal antibody, and evaluated the specificity and sensitivity of this method. Although BGS activity was detected in semen sensitively by this method, it was not detected in saliva, urine, breast milk, blood or vaginal secretions. Since the concentration of p 84 in semen was independent of the secretion status, the status can be determined as non-secretor when p 84 but not BGS activity was detected. To determine the stability of BGS activity on p 84, dried stains of semen on filter paper were kept at 4, 26, and 37 degrees C for 8 months, 2 years and 1 month, respectively, and their BGS activities were examined. After 8 months at 4 degrees C, over 60% of the original BGS activity was recovered from the stain. The activity could be detected even from a square as small as 0.25 by 0.25 cm. After 1 month at 37 degrees C and 2 years at 26 degrees C, 31 and 20% of the BGS activity, respectively, still remained. It could be detected from the pieces of 1.0 by 1.0 cm and 0.5 by 0.5 cm squares, kept for 1 month at 37 degrees C and 2 years at 26 degrees C, respectively. Finally, semen was mixed with saliva or blood at varying volumetric ratios and used for the sources of dried stains. The BGS activity of p 84 could be detected in the stains until the ratio between semen and saliva or blood reached 1:4. We conclude that this sandwich ELISA offers a more sensitive and specific method for determining the ABO blood type of semen samples obtained from sexual assault victims than existing methods, such as the conventional absorption-elution and classical hemagglutination-inhibition tests.

ABO Blood-Group System↗