Biomedical subjects

M Takaya

Publications and source records attributed to M Takaya.

At least 19 recordsLinked to original sources

PubMed2001

Estimation of fibrous aerosol deposition in upper bronchi based on experimental data with model bifurcation.

Lung deposition of fibrous aerosol was studied by using a model of the lung bifurcation with dimensions based on the symmetric model A of Weibel. The fibrous aerosols were introduced to the model under steady inspiratory flow conditions. Glass fibers depositing in the daughter tubes and these escaping from them were observed under a scanning electron microscope (SEM). The deposited fractions were calculated for each length and diameter using a bivariate lognormal distribution. In this study the authors propose empirical equations to estimate total deposited fractions of fibrous aerosol at upper bronchi. The dimensionless relationship among deposited fractions Fd, Stokes number St for randomly-oriented fibers and interception parameter I were used to estimate the deposited fraction at arbitrary position in the upper bronchi. The calculation procedure for Fd(St,I) consists of two steps: the determination of the four deposited fractions, Fdn for each In (n=1-4) followed by interpolation or extrapolation from Fdn to find the deposited fraction Fd at a given I. With this procedure, it is possible to determine the deposited fraction Fd in the range of 2 x 10(-3)<St<5 x 10(-2) and 5 x 10(-4)<I<5 x 10(-2). Penetration from the trachea to the 10th generation of lung bifurcation was calculated for several cases of fiber diameter, length and flow rate. In the case corresponding to an inspiration of 500 cm3 air at a constant rate for 2 s, more than half of the fibers with a length of 100 microm and diameter of 3 microm are deposited at upper bronchi but more than 90% of fibers of the same length and 1 microm in diameter pass through the region.

Aerosols↗

PubMed2001

Lung lesions induced by intratracheal instillation of vanadium pentoxide powder in rats.

To clarify acute toxicity and histopathological changes in the lung after exposure to V2O5 powder, rats (SD, male, n=66) were observed for 4 weeks after an intratracheal administration of V2O5 powder (geometric mean diameter 0.31 microm, geomertic standard deviation sigmag=2.19) at three doses (0.88, 3.0, 13.0 mg/kg body weight). The histopathological lung lesions were developed dose-dependently, and characterized by exudative inflammation, injury of alveolar macrophages, and swelling and mucous degeneration in the broncho-bronchiolar epithelia. Growth rate of the V2O5 powder-instilled rat was also retarded dose-dependently. The V2O5 powder used was composed of not coagulated but well dispersed particles consisting of vanadium pentoxide of more than 99.8% (w/w) with vanadium tetraoxide of less than 0.2%. The V2O5 powder was found to be 8 times more soluble in an artificial biological fluid "Gamble's solution" than in a pure water. From the present findings as well as those from the related literature, it was inferred that the histopathological lesions induced by the intratracheally instilled V2O5 powder are caused not only by the V2O5 particles per se but also by vanadium ions dissolved from the particles into the lung fluid.

Air Pollutants, Occupational↗

PubMed2000

Laboratory measurement of hazardous fumes and gases at a point corresponding to breathing zone of welder during a CO2 arc welding.

Concentrations of fumes, ozone (O3), carbon monoxide (CO), nitric oxide (NO), manganese (Mn) and total and hexavalent chromium (Cr) as well as size distribution of fumes were measured at a point corresponding to the welder's breathing zone during CO2-arc welding, using a welding robot and three kinds of wires. Concentrations of fumes, O3, CO, Mn and total-Cr were found to exceed their corresponding occupational exposure limit (OEL) values, while the concentrations of NO and Cr(VI) were below those OEL levels. Airborne concentration of Mn exceeded its OEL value, and the Mn content was 8 times higher in welding fumes than in the wire. Using an additive equation of OEL and exposure concentration of each hazardous component, health risk in welders with combined exposure to welding fumes and gases was assessed as 18.6 to 46.0 times of OEL, which exceeded the unity. This finding suggests that effective protection of welders from the exposure can be attained by use of the supplied-air respirator or combined use of a dust respirator and a local exhaust system.

Air Pollutants, Occupational↗

PubMed2000

Selective determination method for vanadium (V) and vanadium (IV) controlling the pH of media for a solid-liquid extraction column.

Solid-liquid extraction separation based on a speciation method was studied for selective determination of vanadium (IV) and vanadium (V). Both V (IV) and V (V) cations transform to oxo-acid anion along with pH changes in the solution. The pH values for the transition points are different from each other and the difference was utilized in the separation. In the first step, particulate samples are dissolved by strong acids such as 1 M H2SO4 or 85% H3PO4. The pH of the strong acidic sample solutions of V (IV) and V (IV) are adjusted to the range between 3 and 4. In this condition, V (IV) is in the form of cation but V (V) is anion. The pH adjusted solution is applied to an anion exchange column. The solution is expected to contain V (IV) only. The trapped V (V) anion is eluted as VO2+ cation by a pH 1 acid. The author and coworker have already developed an HPLC separation method utilizing this separation concept. However, the HPLC method has some limitations, mainly originated in physical and chemical weaknesses of the HPLC column. In the present study, a firm solid-liquid column is adopted to replace the feeble HPLC column as a separation device. And a simple and convenient pH adjustment technique for making the sample solution is investigated at the same time. With these improvements, the speciation method developed with strong acidic solutions could determine the amount of V (IV) and V (V) in various environmental and biological samples.

Chromatography, High Pressure Liquid↗

PubMed1999

Development of an analytical method for beryllium in airborne dust by micellar electrokinetic chromatography.

The separation of diacetylacetonato-beryllium [Be(acac)2] from acetylacetone was achieved with micellar electrokinetic chromatography (MEKC) followed by subsequent beryllium analysis carried out using capillary electrophoresis. Analysis using a separation and absorption detector, with a 50 microns capillary cell, could detect approximately 1000 ppb of beryllium in the final sample. Be(acac)2 is a promising reagent for absorption spectrophotometry, because its molar absorption coefficient, (32,000 l mol-1 cm-1) is very large. As the complex and acetylacetone have a similar absorption wavelength, the excess free ligand must removed from the sample to be measured. Acetylacetone is a weak acid with keto-enol tautomerism in aqueous solution. Acetylacetone and neutral Be(acac)2 should be separated with capillary zone electrophoresis (CZE) using a neutral or basic buffer solution as the mobile phase. Although the pH and temperature of the mobile phase were optimized, separation with CZE was interfered with by a portion of acetylacetone. This interfering portion seems to be a neutral keto-form with the same migration time as Be(acac)2. As a neutral species separation method, MEKC with sodium dodecyl sulfate was tried and the separation was completed. The optimum pH value and buffer temperature are pH 7.8 and 15 degrees C, respectively.

Air Pollutants↗

PubMed1998

A probable case of chronic occupational thallium poisoning in a glass factory.

A male worker who handled thallium-containing raw material for glass manufacturing over a period of four years complained of alopecia, abdominal pain, diarrhea and tingling in the four extremities. Neurological examination of this patient revealed signs of mild glove-stocking-type polyneuropathy. Lower sensory nerve conduction velocity of the median nerve in the right hand than in the left hand suggested that conduction function in the dominant hand was reduced. The thallium content of the hair, as determined by an ICP-MS method, was 20 ng/g for the patient and 576 ng/g for his successor in the time of 32 months and 13 months, respectively, after they had ceased their glass production work. Those levels of thallium exposure were considered high, compared with the control levels so far reported. The clinical course of signs and symptoms, neurophysiological findings and thallium content of hair suggested that the patient suffered from chronic poisoning due to occupational exposure to thallium-containing dust.

Abdominal Pain↗

PubMed1997

Correlation between transcranial Doppler ultrasonography and regional cerebral blood flow in experimental intracranial hypertension.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasonography (TCD) provides useful information on cerebral circulation even under raised intracranial pressure. This study was designed to evaluate the correlation between cerebral blood flow (CBF) and TCD parameters under conditions of boundary intracranial hypertension that can cause brain death. METHODS: Intracranial pressure was raised by inflation of a supratentorial epidural balloon in cats. Blood flow velocity of the middle cerebral artery was measured transorbitally with microvascular Doppler sonography, and intracranial pressure and CBF were evaluated. RESULTS: In this study, four characteristic flow patterns were observed, appearing in the following order with progressive increases in intracranial pressure: sharp wave, systolic flow, systolic spike, and no flow. These flow patterns showed a significant correlation with flow velocity, CBF, the pulsatility index, and cerebral perfusion pressure. The systolic-spike and no-flow patterns and pulsatility index over 4.0 indicated decreased CBF, under 10% of control values. CONCLUSIONS: The critical level of brain circulation can be detected by Doppler sonography, indicating that TCD is available as a tool for the assessment of cerebral circulatory arrest in brain death.

Animals↗

PubMed1997

[Treatment with pilocarpine hydrochloride for sicca symptoms in Sjögren's syndrome].

We studied the efficacy of oral pilocarpine hydrochloride (9 mg/day, three times daily) on sicca symptoms in 21 patients with Sjögren's syndrome (SS) of the patients, 19 continued the treatment for at least one month, and subjective improvement of dry mouth and dry eye was observed in 10 patients (53%) and 5 patients (26%), respectively. As adverse effects, diaphoresis was most frequently recognized, but it was generally mild and tolerable. In the four patients who have been taking pilocarpine for 12 months, any severe side effects have not been observed. Since the incidences of clinical improvement of sicca symptoms and adverse effects were comparable with the other studies reported from US or Europe, our treatment protocol using pilocarpine hydrochloride (9 mg/day) was considered as appropriate for Japanese SS patients.

Administration, Oral↗

PubMed1996

The coexistence of systemic sclerosis and rheumatoid arthritis in five patients. Clinical and immunogenetic features suggest a distinct entity.

To elucidate the clinical characteristics and pathogenesis of scleroderma-rheumatoid arthritis (SSc-RA) overlap syndrome, we analyzed the clinical features of 5 patients with SSc-RA overlap. Their HLA phenotypes and genotypes were also determined. Generalized skin sclerosis, severe seropositive polyarthritis, pulmonary fibrosis, anti-topoisomerase I antibodies, and HLA-DR4,53;DQA1*0301;DBQ1*04 haplotype were observed in all of the patients. Similar clinical features were recognized in most of the 10 cases reported previously. Our case studies indicate that SSc-RA overlap may be a distinct entity.

Aged↗

PubMed1996

Vagus nerve stimulation induces a sustained anticonvulsant effect.

PURPOSE: Stimulation of the vagus nerve can effectively abort several types of experimentally induced seizures in animals when administered near the time of seizure onset. Indirect evidence from human trials and animal studies suggests that the anticonvulsant effects of vagus nerve stimulation (VNS) extend beyond the duration of stimulation. We used the pentylenetetrazol model to determine whether VNS exerts a persistent anticonvulsant effect. METHODS: VNS (1 mA, 30 Hz, 500 microseconds pulse width) was administered continuously for 0.1, or 60 min, or intermittently (30 s on, 5 min off) for 60 min, to awake and freely moving animals. After the end of stimulation, pentylenetetrazol (50 mg/kg i.p.) was administered to induce seizures. Time-course studies were also performed, consisting of 60 min of VNS followed by pentylenetetrazol injection after 0, 3-, 5-, and 10-min intervals. RESULTS: The greatest anticonvulsant effect occurred after 60 min of continuous VNS, which prevented convulsions in four of 12 rats and reduced significantly seizure duration, the total number of seizures, and number of tonic seizures. Intermittent VNS was less effective than continuous stimulation for 60 min, but more effective than that for 1 min. The anticonvulsant effect declined in a time-dependent fashion after discontinuation of VNS, with return to nonstimulated control values by 10 min. CONCLUSIONS: The results of this study verify a persistent VNS-induced anticonvulsant effect and indicate that its efficacy is dependent on the cumulative stimulus duration.

Animals↗

PubMed1996

Decay-accelerating factor (DAF, CD55)-negative T lymphocytes in the peripheral blood of Sjögren's syndrome patients.

OBJECTIVE: To clarify possible associations of decay-accelerating factor (DAF, CD55), expressed on circulating lymphocyte subsets and other hematologic cells, with corresponding cytopenias observed in primary Sjögren's syndrome (SS). METHODS: DAF expression on peripheral blood (PB) cells was determined in 21 patients with SS and 11 healthy controls by single or 2 color flow cytometry. RESULTS: In the PB from SS patients, anemia, monocytopenia, neutropenia, and lymphocytopenia were observed. Compared to the controls, the percentages of DAF-negative cells were higher in CD4+ and CD8+ T cell subsets from SS patients, but the expression of DAF was similar in the other PB cells, including CD19+ B cells, CD56+ NK cells, monocytes, granulocytes, and erythrocytes. The percentages of DAF-negative cells among the CD4+ and CD8+ cells were positively correlated in SS patients, but the numbers of cells in both subsets were decreased in those patients being treated with prednisolone. However, these proportional changes are thought to reflect a decrease in the numbers of DAF-positive CD4+ and CD8+ cells, because the absolute numbers of circulating DAF-positive CD4+ and CD8+ cells, but not DAF-negative cells, were significantly decreased in SS patients. In addition, DAF-negative cells were detectable in both CD45RA+ (naive) and CD45RO+ (memory) T cells from healthy individuals, and the expression of DAF was remarkably increased in both subsets after in-vitro activation with concanavalin-A. CONCLUSION: DAF-negative cells are proportionally increased among circulating CD4+ and CD8+ T cells in SS patients, although such changes are due to decreased numbers of DAF-positive cells within each subset. When considering previous observations, the DAF-negative CD4+ and CD8+ cells probably belong to activated T cell subsets in both SS patients and controls. However, the patterns of DAF expression seemed to be different between activated T cells recognized in the PB, and those induced by in vitro-stimulation.

Adult↗

PubMed1995

Study of aneurysmal subarachnoid hemorrhage in Izumo City, Japan.

BACKGROUND AND PURPOSE: Estimation of the actual incidence rate of subarachnoid hemorrhage and evaluation of the treatment require the inclusion of all patients in a defined geographic area. METHODS: During 1987 through 1992 in Izumo City, Japan, we estimated the incidence rate of subarachnoid hemorrhage by including dead-on-arrival patients and by further adding the results obtained after reviewing all death certificates registered in this city in the corresponding period. In addition, we compared the management and surgical outcomes in hospitalized patients from 1987 through 1992 with outcomes from 1980 through 1986. RESULTS: During 1987 through 1992, we diagnosed 123 patients as having subarachnoid hemorrhage. The crude and the age- and sex-adjusted incidence rates using the 1990 population statistics for Japan were 25 (95% confidence interval, 21 to 30) per 100,000/y and 23 (95% confidence interval, 19 to 28) per 100,000/y for all ages, respectively; these occurrences are the highest among those reported to date. Of these patients, 8% died before receiving medical attention, 27% in the first week, and 39% at 1 month. The survival curve for 2 years improved significantly from 1980-1986 to 1987-1992 in patients with admission grades 4 and 5 (P = .035) and in operated patients with preoperative grades 1 through 3 (P = .036). However, there was little improvement in the overall management results (P = .168), possibly because patients with high risk and/or old age were admitted and/or diagnosed more often in the latter period. CONCLUSIONS: The incidence rate of subarachnoid hemorrhage is much higher than that reported so far in the literature, and despite improvement of management and surgical therapy, the actual case-fatality rate is still high, mainly because of the high mortality rate directly associated with the primary bleeding.

Adult↗

PubMed1995

[Isotypes and subtypes of anti-SS-A and/or SS-B antibodies in different subgroups of Sjögren's syndrome].

Profiles of anti-SS-A/SS-B antibodies, including their isotypes and subtypes, in patients with primary Sjögren's syndrome (SS) were similar to those in SS patients with systemic lupus erythematosus (SLE), except for anti-SS-A52-Kd/60-Kd antibody profiles. The incidence and titers of these antibodies in SS patients with rheumatoid arthritis, however, were lower than those in primary SS or SS patients with SLE. It is suggested that IgA anti-SS-A/SS-B antibodies are produced in the salivary gland. In addition, IgG1 anti-SS-A antibodies were dominant in all groups of SS patients examined. The results indicate a preferential activation of Th2 helper T cells in SS.

Antibodies, Antinuclear↗

PubMed1995

[Systemic sclerosis with various gastrointestinal problems including pneumoperitoneum, pneumatosis cystoides intestinalis and malabsorption syndrome].

We describe here an experience of successful treatment of systemic sclerosis (SSc) complicated with various gastrointestinal (GI) problems including pneumoperitoneum, pneumatosis cystoides intestinalis and malabsorption syndrome. A 35-year-old female had developed selerodactyly since February, 1990. She had been treated under the diagnosis of SSc at other hospital. She had required several hospitalizations because of nausea, vomitting and abdominal distension, but her GI symptoms had gradually deteriorated. In April 1993, she was referred to our hospital and admitted for the treatment of her GI problems. On admission, she had systemic cutaneous sclerosis and marked abdominal distension without peritoneal signs was recognized. Chest and abdominal roentgenograms demonstrated massive free air under the diaphragm, marked dilation of small and large bowels, and multiple intestinal cysts (pneumatosis cystoides intestinalis ; PCI). We treated her GI problems with various modalities combined with medications, oxygen breathing, intravenous hyperalimentation and hyperbaric oxygen therapy. Pneumoperitoneum and PCI had disappeared after 8 courses of hyperbaric oxygen therapy and her GI symptoms had been well controled by intravenous hyper alimentation. Thereafter, she has been on intermittent parenteral nutrition through subcutaneous port inplantation. During the courses of this treatment, she developed an episode of Wernicke-Kolsakoff (W-K) syndrome which was considered to associate with malabsorption syndrome. The W-K syndrome had recovered by intravenous administration of vitamin B1.

Adult↗

PubMed1994

[Studies on pyridazinone derivatives. XVI. Analgesic-antiinflammatory activities of 3(2H)-pyridazinone derivatives].

In order to examine analgesic and antiinflammatory activities of the position isomers of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (1, emorfazone), an analgesic-antiinflammatory drug, 5-ethoxy-2-methyl-4-morpholino-3(2H)-pyridazinone (2), 6-ethoxy-2-methyl-4-morpholino-3(2H)-pyridazinone (3) and 6-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (4) were prepared. Since 4 showed the most strong activity among the compounds tested, various 6-alkoxy- or 6-allyloxy-2-alkyl- or 2-cyclohexyl- or 2-phenyl-5-substituted amino-3(2H)-pyridazinones (15, 16) were prepared and examined for their activities. As a result, 4 and 2-methyl-5-morpholino-6-n-propoxy- or 6-n-butoxy-3(2H)-pyridazinone (15b, c) and 6-ethoxy-2-ethyl-5-morpholino-3(2H)-pyridazinone (15 l) were revealed to be more potent in analgesic and antipyretic activities than commercial drugs (1, aminopyrine, mepirizole, tiaramide HCl, phenylbutazone, mefenamic acid). On the basis of the available data, the structure-activity relationship in a series of 6-alkoxy-2-alkyl-5-substituted amino-3(2H)-pyridazinones (15, 16) was also discussed.

Animals↗

PubMed1994

Circadian variations and prednisolone-induced alterations of circulating lymphocyte subsets in man.

We determined the circadian variations and prednisolone (PSL)-induced alterations of circulating lymphocyte subsets in 10 healthy adults by two-color flow cytometry using monoclonal antibodies to various lymphocyte subsets in order to collect fundamental data for monitoring of the subsets in clinical practice. This study first examined the changes of CD5+ B cells, gamma delta+ or gamma delta-T cells, activated (HLA-DR+) CD4+ or CD8+ cells, CD11b+ or CD11b-CD8+ cells, and natural killer (NK) cell subsets (CD16+CD57-, CD16+CD57+, CD16-CD57+), in addition to other subsets described before. Compared with the base line values obtained at 9:00 (AM) on day 1, lymphocytes, total B cells, CD5+ B cells, total T cells, gamma delta-T cells, CD4+ cells, activated CD4+ cells, CD45RA-CD4+ cells, and activated CD8+ cells were significantly increased at 20:00 (PM). However, the numbers of CD45RA+CD4+ cells, CD11b+ or CD11b-CD8+ cells and three NK cells subsets did not show significant circadian variations. After oral PSL (30 mg), which was given at 7:00 (AM) on day 2, lymphocytes and almost all lymphocyte subsets, except for CD16+CD57- cells, were significantly decreased; these changes recovered between 13 and 26 hours after PSL administration. The circadian variations and PSL-induced alterations of lymphocyte subsets were relatively comparable, but PSL administration cause a decrease in a wider range of lymphocyte subsets including relatively corticosteroid-resistant subsets such as CD45RA+CD4+ cells, CD8+ cell and NK cell subsets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Speciation of vanadium(IV) and vanadium(V) using ion-exchange chromatography and ICP-AES.

A speciation method for vanadium(IV) and vanadium(V) is presented that uses a combination of HPLC and ICP-AES. In this method, 1 mM HNO3 solution and 100 mM HNO3 solution were applied in sequence as eluent. A vanadium(IV) and vanadium(V) mixture was injected into a HPLC anion-exchange column; and vanadium(IV) cation was then eluted by 1 mM HNO3, while vanadium(V) oxoacid anion was trapped on the column. After this separation, vanadium(V) was eluted as a cation from the column by 100 mM HNO3. Vanadium was detected by ICP-AES. In this separation, about 15% of vanadium(V) interfered with vanadium(IV), and trace vanadium(IV) interfered with vanadium(V). This interference could be estimated by simple calculation based on standard observations, and the speciation of vanadium(IV) and vanadium(V) was performed. The lower determination limit was 1 microgram/mL, which is insufficient to speciate vanadium sampled by conventional sampling methods in a working environment. However, impurity of the other valent vanadium species in a vanadium(V) reagent can be determined by the present method, which should be valuable in precisely assessing the toxicities of vanadium species.

Chromatography, High Pressure Liquid↗

PubMed1994

Intraoperative use of Doppler ultrasound and endoscopic monitoring in the stereotactic biopsy of malignant brain tumors. Technical note.

An intraoperative monitoring tool is described that prevents mechanical injury to intracerebral vessels during stereotactic surgery. The method, which combines pulse Doppler ultrasonography and fiberendoscopy, allowed stereotactic biopsy to be performed without serious intracerebral bleeding in 25 patients with hypervascular malignant brain tumors, 13 with glioblastoma multiforme, five with anaplastic astrocytoma, five with metastatic tumor, and two with malignant lymphoma. The ultrasound apparatus has a built-in fast-Fourier transformation system analyzer and an improved filtering system that provide real-time measurement of blood flow velocity. The source of flow (arterial or venous) could be identified by both real-time sonography and acoustic signal frequencies. It was possible to measure the size and distance of a vessel by adjusting the Doppler signal gain dial from initially waxing to waning sounds, because the acoustic signal was adjusted to the axial flow of each vessel in 0.1-mm steps. Each of three Doppler probes (1 mm, 2 mm, and 3 mm in diameter) fit through the outer cannula of the biopsy needle. Vessels located within 7 mm from the tip of these probes could be detected easily and rapidly, so the biopsy needle could be advanced safely to the desired target in 7-mm steps. If sonograms revealed blood flow, indicating the presence of larger vessels in the intended stereotactic trajectory, the angle of the needle was changed slightly to avoid vascular injury. Because the fiberendoscope was connected to a video processor, the vessel could be visualized at a higher magnification on the video display, unless there was active bleeding. This technically simple and reliable system enhances operative safety while maintaining accuracy.

Biopsy↗