Search PubMed⌕ Search

Biomedical subjects

H Nakashima

Publications and source records attributed to H Nakashima.

At least 73 records · Page 4Linked to original sources
PubMed2001

Comparison of transthoracic Doppler echocardiography and natriuretic peptides in predicting mean pulmonary capillary wedge pressure in patients with chronic atrial fibrillation.

The purpose of this study was to assess whether transthoracic Doppler echocardiography and serum natriuretic peptide levels could predict mean pulmonary capillary wedge pressure (PCWP) in patients with chronic atrial fibrillation. We examined mitral flow velocity and pulmonary venous flow (PVF) velocity patterns in 32 patients with chronic atrial fibrillation. Plasma A-type and B-type natriuretic peptide (ANP, BNP, respectively) levels in the peripheral vein were measured. Significant correlations were observed between mean PCWP and the following: peak velocity (r = 0.51) and deceleration time (r = -0.65) of the mitral flow; peak velocity (r = 0.64) and deceleration time (r = -0.80) of the PVF; BNP (r = 0.60); and ANP (r = 0.36). Stepwise multiple linear regression analysis selected PVF deceleration time and mitral flow deceleration time as independent predictors of PCWP. A cutoff value of PVF deceleration time of < or =150 ms and a mitral flow deceleration time of < or =100 ms predicted a mean PCWP of > or =18 mm Hg, with a sensitivity of 100% and 80% and a specificity of 96% and 85%, respectively. In conclusion, PVF deceleration time and mitral flow deceleration time obtained from transthoracic Doppler echocardiography are more accurate predictors of mean PCWP than values obtained with natriuretic peptides in patients with chronic atrial fibrillation.

Aged↗
PubMed2001

Intravenous chlorhexidine gluconate causing acute respiratory distress syndrome.

CASE REPORT: A 67-year-old man undergoing a colectomy for colon cancer was unintentionally administered 0.8 mg of chlorhexidine gluconate intravenously and subsequently developed acute respiratory distress syndrome. The operation was discontinued immediately. Respiratory failure progressed despite three cycles of plasma exchange beginning on day 1. Extracorporeal membrane oxygenation for 72 h beginning on day 3 was associated with dramatic improvement. The patient showed complete recovery of intellectual function and subsequently underwent a colectomy with lymph node dissection for colon cancer. CONCLUSION: For acute respiratory distress syndrome secondary to chlorhexidine gluconate intoxication, consideration should be given to the treatment of initial respiratory distress and subsequent pneumonia. The benefit of extracorporeal membrane oxygenation and plasma exchange may merit further investigation.

Aged↗
PubMed2001

Association of CTLA-4 but not CD28 gene polymorphisms with systemic lupus erythematosus in the Japanese population.

OBJECTIVE: Systemic lupus erythematosus (SLE) in a multisystem autoimmune disorder characterized by multiorgan pathology and autoantibodies against a variety of autoantigens. The CD28 and CTLA-4 genes might be candidate genes for SLE, because costimulation signals from CD80/CD86 to CD28/CTLA-4 have been suggested to play an important role in the activation or inactivation of T lymphocytes. METHODS: We investigated three polymorphic regions within the CTLA-4 gene, a C/T base exchange in the promoter region -318 (CTLA-4 -318C/T), an A/G substitution in the exon 1 position 49 (CTLA-4 49A/G), an (AT)(n) repeat polymorphism in the 3' untranslated region of exon 4 [CTLA-4 3' (AT)(n)], and a CD28 gene polymorphism, a T/C substitution in the intron 3 position +17 (CD28 IVS3+17T/C), in SLE patients and controls. RESULTS: SLE patients had significantly higher frequencies of the CTLA-4 49G allele (P=0.003) and of the CTLA-4 (AT)(n) 106 bp allele (P=0.0008) than controls. We also found a strong linkage disequilibrium between the A allele of CTLA-4 49A/G and the 86 bp allele of CTLA-4 3' (AT)(n). On the contrary, no association was found between SLE and CTLA-4 -318C/T or CD28 IVS3 +17T/C. CONCLUSION: We conclude that the CTLA-4 gene appears to play a significant role in the development of SLE in the Japanese population.

Abatacept↗
PubMed2001

An experimental study on radiation streaming through a labyrinth in a proton accelerator facility of intermediate energy.

A radiation streaming experiment has been carried out at the Takasaki Ion Accelerator Facility for Advanced Radiation Application at the Japan Atomic Energy Research Institute in a room housing a Cu target irradiated with 68 MeV protons and in a labyrinth of three-legs having a total length of 29 m. In the experiment, neutron and gamma ray energy spectra, neutron reaction rates, and neutron and gamma ray dose equivalent rates were measured using various counters and dosimeters. The experimental data show the applicability of some empirical formulas for estimating the thermal neutron flux in a room and neutrons streaming in a labyrinth designed for a proton accelerator operating in the intermediate energy region. The data suggest that it is mandatory to estimate the gamma ray dose equivalent rate in a labyrinth, which is dominated by the secondary gamma rays due to the neutron capture reaction.

Academies and Institutes↗
PubMed2001

Random monoallelic expression of three genes clustered within 60 kb of mouse t complex genomic DNA.

Mammals achieve gene dosage control by (1) random X-chromosome inactivation in females, (2) parental origin-specific imprinting of selected autosomal genes, and (3) random autosomal inactivation. Genes belonging to the third category of epigenetic phenomenon are just now emerging, with only six identified so far. Here we report three additional genes, Nubp2, Igfals, and Jsap1, that show 50%-methylated CpG sites by Southern blot analyses and primarily monoallelic expression in single-cell allele-specific RT-PCR analysis of bone marrow stromal cells and hepatocytes. Furthermore, we show that, in contrast to X inactivation, alleles can switch between active and inactive states during the formation of daughter cells. These three genes are the first in their category to exist as a tight cluster, in the proximal region of mouse chromosome 17, providing a thus far unique example of a region of autosomal random monoallelic expression.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Comparison of in-phantom dose distributions for coronary angiography using an x-ray machine and synchrotron radiation.

Coronary cineangiography using synchrotron radiation is anticipated, owing to the high intensity and availability of monoenergy. To investigate allowable dose levels in clinical application, absorbed dose distribution in a tissue substitute phantom for a conventional x-ray machine was measured with thermoluminescent dosimeters at the University of Tsukuba under the practical conditions used for digital angiography. The dose rate at a 0.5-cm depth was 0.145 Gy/s, and the dose per frame was 0.725 mGy for the irradiation period of 5 ms per frame. For synchrotron radiation, the dose distribution measurement was made at a 5-GeV AR (Accumulation Ring) of the High Energy Accelerator Research Organization, in which a polymethylmethacrylate (PMMA) phantom was irradiated with the strongest beam available at the facility, which was 33.32 keV, 5.2 x 6.2 cm2 beam. Using this beam, a 1-mm-diameter coronary artery has been visualized at 1% iodine concentration at the AR. Nonhomogeneous strength distribution in the beam was observed in the vertical direction. The maximum dose rate was 0.556 Gy/s, and it attenuated to 1/3000 at a 30-cm depth in the beam center. At the deep positions, the doses were influenced by the high harmonics, which was confirmed with an EGS4 Monte Carlo calculation. Outside the beam, beam contamination on both sides of the main beam affected the doses. For comparison to the x-ray machine, the measured dose was analytically converted to that needed for a 5.2 x 16 cm2 beam that is used for clinical application. The dose rate at 0.5-cm depth was found to be 0.215 Gy/s, which is 1.48 times larger than that for x-rays. Moreover, the attenuation rate in the phantom was significantly greater than that of the x-ray machine, because of the difference of the energy spectra between the x-rays and synchrotron radiation used.

Biophysical Phenomena↗
PubMed2001

Anti-human immunodeficiency virus activity of YK-FH312 (a betulinic acid derivative), a novel compound blocking viral maturation.

Betulinic acid, a triterpenoid isolated from the methyl alcohol extract of the leaves of Syzigium claviflorum, was found to have a potent inhibitory activity against human immunodeficiency virus type 1 (HIV-1). Betulinic acid derivatives were synthesized to enhance the anti-HIV activity. Among the derivatives, 3-O-(3',3'-dimethylsuccinyl) betulinic acid, designated YK-FH312, showed the highest activity against HIV-induced cytopathic effects in HIV-1-infected MT-4 cells. To determine the step(s) of HIV replication affected by YK-FH312, a syncytium formation inhibition assay in MOLT-4/HIV-1(IIIB) and MOLT-4 coculture, a multinuclear-activation-of-galactosidase-indicator (MAGI) assay in MAGI-CCR5 cells, electron microscopic observation, and a time-of-addition assay were performed. In the syncytium formation inhibition assay or in the MAGI assay for de novo infection, the compound did not show inhibitory effects against HIV replication. Conversely, no virions were detected in HIV-1-infected cell cultures treated with YK-FH312 either by electron microscopic observation or by viral yield in the supernatant. In accordance with a p24 enzyme-linked immunosorbent assay of culture supernatant in the time-of-addition assay, YK-FH312 inhibited virus expression in the supernatant when it was added 18 h postinfection. However, Western blot analysis of the cells in the time-of-addition assay revealed that the production of viral proteins in the cells was not inhibited completely by YK-FH312. These results suggest that YK-FH312 might affect the step(s) of virion assembly and/or budding of virions, and this is a novel mechanism of action of an anti-HIV compound.

Anti-HIV Agents↗
PubMed2001

Effects of cavotricuspid isthmus catheter ablation on paroxysmal atrial fibrillation.

It has been demonstrated that successful cavotricuspid isthmus ablation of typical atrial flutter combined with atrial fibrillation (AF) sometimes influences the preablation history of paroxysmal AF. However, the effectiveness of only isthmus ablation on AF itself is unclear. Endocardial catheter mapping during induced AF was performed around the tricuspid annulus using duodecapolar clectrode catheters in 39 patients with drug-refractory paroxysmal AF. Isthmus ablation was performed in 16 patients (41%) in whom catheter mapping during AF showed an organized activation pattern around the tricuspid annulus. During a mean follow-up of 12.3 months, isthmus ablation was successful in preventing AF in 12 (75%) patients, 8 without medication and 4 with a previously ineffective drug. This success group had a significantly higher F wave amplitude in lead V1 (0.29+/-0.10 vs 0. 15+/-0.04 mV, p < 0.01), a higher left ventricular ejection fraction (74+/-9 vs 58+/-2%, p < 0.05), and a smaller left atrial dimension (35+/-6 vs 43+/-4 mm, p < 0.05) than the failure group. Isthmus ablation may be effective in preventing paroxysmal AF with an organized activation pattern around the tricuspid annulus. F wave amplitude, left ventricular ejection fraction, and left atrial dimension were significant predictors of success.

Aged↗
PubMed2001

Coil embolization of intradural pseudoaneurysms caused by arterial injury during surgery: report of two cases.

Intradural pseudoaneurysms arose in two patients as a result of arterial injury incurred during surgery. In the first patient, the pseudoaneurysm developed in the middle cerebral artery, at the site of vessel perforation during aneurysmal surgery. In the second patient, the pseudoaneurysm developed in the anterior communicating artery after removal of a tuberculum sellae meningioma. These aneurysms had small ostia and were successfully embolized with electrolytically detachable coils. The clinical features and the treatment of intracranial pseudoaneurysms are discussed.

Adult↗
PubMed2001

[Use of the GDC for embolization of a tumor fed by a cavernous branch of the internal carotid artery].

Currently, embolization of small branches of the internal carotid artery (ICA) can be embolized through superselective microcatheterization, followed by the injection of liquid or particulate embolic materials. Often, however, a microcatheter cannot be placed in a stable enough position to allow an endovascular surgeon to perform a safe embolization, and the reflux of embolic agents into the main trunk of the ICA is a major concern. Meticulous technique and a detailed knowledge of the vascular anatomy of the cavernous sinus region are necessary to maximize devascularization of the lesion and to minimize the risk of complications. This report describes the case of a patient with a hypervascular tumor whose feeding vessel from the cavernous ICA was successfully occluded with polyvinyl alcohol (PVA) combined with a regular Guglielmi detachable coil (GDC). A 62-year-old woman had a left-sided petroclival meningioma, which was diagnosed based on computed tomography and magnetic resonance studies. Transfemoral angiographic studies demonstrated that the tumor was fed by intracavernous branches of the left ICA. We believed that another embolic agent would have presented a risk of reflux into the ICA, with possible unwanted occlusion of normal intracranial arteries. A single GDC was sufficient to occlude the feeding artery, and the patient underwent successful surgery 3 days after the endovascular procedure. The GDC can eliminate the ICA supply to hypervascular tumors safely when liquid or particle embolic materials would present a risk of reflux into normal arteries. This device can be positioned and repositioned and can be detached without mechanical force. It may also decrease the risk of unwanted embolization of normal intracranial arteries.

Carotid Artery, Internal↗
PubMed2001

[Topics of clinical physiological tests--pulmonary function--proposal of physio-chemical tests].

Pulmonary functions are classified as respiratory and non-respiratory. Although the mechanisms of non-respiratory pulmonary function have already been established, no new tests of respiratory pulmonary function have been developed for a long time. Thus, we report here a new analytic test of respiratory pulmonary functions. The new analytic method is physio-chemical analysis, in which the chemical factors of lungs are estimated from the physiological characteristics of lung during respiration. As examples, this report shows the method of exchanging mechanical energy to chemical energy in a comparison of lung ventilatory work between smokers and non-smokers. This report discusses the relationship between chemical energy and ATP in the blood of pneumoconiosis patients.

Aged↗
PubMed2001

[Implementation and evaluation of public relations activity in a community health program].

OBJECTIVE: This study evaluated public relations activity in a community health program in order to develop effective strategies to attract the public attention for the program. METHODS: An intervention study was conducted on public relations for "Nutrition Seminar for Citizens," sponsored by the Health Department of Machida City, Tokyo, in October, 1999. One ward in the city was selected as an intervention area, and another ward which had similar demographic and geographic characteristics was chosen as a control area. Two target populations were defined; one was women in their 20s to 60s (#1) and the other was those who had previously never utilized community health programs sponsored by the city (#2). Handbills were used as the medium for public relations for the seminar. These announced the time, place and content of the nutrition seminar and were designed by authors with special attention to catchphrases, colors and fonts. Handbills were distributed in the intervention area through elementary schools, local voluntary organizations and local health volunteers. In addition, the authors directly handed them out to people in front of two supermarkets in the town. The sources of seminar information were requested from the participants of the Nutrition Seminar with a self-administered questionnaire. RESULTS: 1. The percentage of participants who received the seminar information from handbills was higher than that of those who used monthly newsletters from the city as a source of information. 2. The percentage of participants from the intervention area was higher than that from the control area. 3. Regarding target populations #1 and #2, there were no differences in participation rates between the intervention and control area. 4. Among the four distribution routes, the local voluntary organization route was the most effective for attracting participants. CONCLUSIONS: The results show that handbills can be an effective medium for pubic relations to increase the number of participants in community health programs. Also, local voluntary organizations can play a crucial role in information transfer in the community because of their high credibility. On the other hand, we could not reach specified target populations with the medium. Further surveys are needed to establish optimal media and routes to reach appropriate target populations in health programs.

Adult↗
PubMed2001

[Usefulness of a new mechanical detachable coil for neurovascular intervention].

The electrolytically detachable platinum coil (Guglielmi Detachable Coil: GDC) is a safe and efficient endovascular tool for treatment of cerebral aneurysms. However, the GDC still has some problems, including a prolonged detaching time and high cost. The Detach Coil System (DCS) is a newly developed platinum detachable coil for the treatment of neurovascular diseases. This has a mechanical "screw" detachment system, which can be detached faster than the GDC. The platinum coil is mounted to the tip of the delivery wire by the "screw" system. For detaching the coil, 20-25 times anti-clockwise rotation of the delivery wire using a "detach locking device" is required. We report our preliminary clinical experience of using the DCS in 11 patients. This series included 5 sacral aneurysms, 3 dissecting aneurysms, and 3 dural arteriovenous fistulas. Seventy-five coils were used in total, of which 5 coils were retrieved and 70 coils were implanted. The detaching time of each DCS was 15-20 seconds, which was much faster than that of the GDC. All lesions were successfully treated without symptomatic complications. In the limited number of cases, our result suggest that the DCS allowed safe and fast endovascular treatment of neurovascular disease at a lower cost.

Adult↗
PubMed2000

Pharmacophore identification of a specific CXCR4 inhibitor, T140, leads to development of effective anti-HIV agents with very high selectivity indexes.

A polyphemusin peptide analogue, T22 ([Tyr(5,12), Lys7]-polyphemusin II), and its shortened potent analogues, T134 (des-[Cys(8,13), Tyr(9,12)]-[D-Lys10, Pro11, L-citrulline16]-T22 without C-terminal amide) and T140 [[L-3-(2-naphthyl)alanine3]-T134], strongly inhibit the T-cell line-tropic (T-tropic) HIV-1 infection through their specific binding to a chemokine receptor, CXCR4. T22 is an extremely basic peptide possessing five Arg and three Lys residues in the molecule. In our previous study, we found that there is an apparent correlation in the T22-related peptides between the number of total positive charges and anti-HIV activity or cytotoxicity. Here, we have conducted the conventional Ala-scanning study in order to define the anti-HIV activity pharmacophore of T140 (the strongest analogue among our compounds) and identified four indispensable amino acid residues (Arg2, Nal3, Tyr5, and Arg14). Based on this result, a series of L-citrulline (Cit)-substituted analogues of T140 with decreased net positive charges have been synthesized and evaluated in terms of anti-HIV activity and cytotoxicity. As a result, novel effective inhibitors, TC14003 and TC14005, possessing higher selectivity indexes (SIs, 50% cytotoxic concentration/50% effective concentration) than that of T140 have been developed.

Amino Acid Sequence↗
PubMed2000

Fluctuating monoplegia due to venous insufficiency by spinal arachnoiditis ossificans.

This is the first report of a patient with venous insufficiency following compressive arachnoiditis ossificans (AO). Symptoms of fluctuating monoplegia and sensory disturbance appeared monthly, lasting several weeks each time. Spinal magnetic resonance imaging (MRI) showed high T2-weighted signal intensity in the posterior portion of the column from T11 to T12 and an intradural lesion with low T2-weighted signal intensity. Neurological function and MRI improved markedly following an operation on AO. The symptoms seen in the present case were due to posterior venous insufficiency following compressive AO.

Aged↗
PubMed2000

A Concise Route to (+)-Estrone.

A concise route to the Torgov diene, the key intermediate of estrone, has been devised using a chiral dioxycyclopentenone as the starting material by employing a sequence of five steps of reactions involving a Lewis acid-mediated Diels-Alder reaction with Dane's diene.

Journal Article↗