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Biomedical subjects

T Ohkubo

Publications and source records attributed to T Ohkubo.

At least 253 records · Page 14Linked to original sources
PubMed1992

Measurement of haloperidol in human breast milk by high-performance liquid chromatography.

A high-performance liquid chromatographic method was developed for the assay of haloperidol in human breast milk. The method involves rapid extraction of haloperidol and chromatography with a reversed-phase C18 column and a mobile phase of phosphate buffer (pH 4.0):acetonitrile (70:30, v/v). Moperone was used as the internal standard. Haloperidol and moperone were detected with ultraviolet detection at 254 nm. The sensitivity was 5 ng/mL of milk, and the standard curve was linear in the concentration range 5-250 ng/mL. The average interassay coefficient of variation for samples with drug in the concentration range 25-125 ng/mL was less than 8.8%. The absolute recovery of haloperidol by the method was greater than 94.4%. No interference with endogenous substances in human milk was observed. The method was used to determine haloperidol levels in breast milk from patients undergoing chronic haloperidol treatment.

Chromatography, High Pressure Liquid↗
PubMed1992

Time course of superoxide generation by leukocytes--the MCLA chemiluminescence system.

This study was performed to examine the pattern of superoxide (O2-.) generation from leukocytes using the O2-. specific chemiluminescence (CL) method. Cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo [1,2-alpha]pyrazin-3-one (MCLA) was used as a CL probe. The appropriate conditions of the MCLA method was first determined for the evaluation of the time course of O2-. generation by leukocytes. The time course of O2-. generation obtained by the MCLA-CL system was compared with that by the luminol-dependent CL, electron spin resonance (ESR)/spin trapping, and cytochrome c systems. Following stimulation by three different stimulants (PMA, OZ, FMLP), leukocytes continuously generated O2-. for up to 5 h in the MCLA-CL system, irrespective of the kind of stimulation. The curves obtained by generation ceased more rapidly in the luminol-CL, ESR/spin trapping, and cytochrome c systems. A 50% activity of the initial value was observed at 70 min in the MCLA-CL system, but 30, 10 and 35 min in the other systems, respectively. The CL or O2-. generation value decreased to less than 1% (possible termination) at 300, 90, 120 and 180 min, respectively. With the exception of ESR studies with OZ, the cell viability was not significantly affected in any of the trials. These results indicate that leukocytes can generate O2-. much longer than previously estimated and that the MCLA-CL-system is the most suitable system for the measurement of the O2-. generation by leukocytes.

Cell Separation↗
PubMed1992

High-performance liquid chromatographic determination of nifedipine and a trace photodegradation product in hospital prescriptions.

A HPLC method is developed for the assay of nifedipine and trace amounts of a photodegradation product in pulverized tablets used in the preparation of hospital prescriptions. After liquid-liquid extraction, nifedipine and its photodegradation product are chromatographed using a reversed-phase system which involves UV detection at 254 nm and the use of two internal standards. The trace photodegradation product in pulverized tablets is determined along with nifedipine by the same procedure. The method is capable of determining 0.5-5.0 micrograms of nifedipine using p-nitronifedipine as the internal standard and 0.01-0.5 micrograms of the photodegradation product using 5-hydroxynifedipine as the internal standard. The standard error is found to not exceed 8.4%. The methods are useful for the study of the disposition or photostability of nifedipine in tablets and pulverized tablets.

Chromatography, High Pressure Liquid↗
PubMed1992

1H-NMR assignment and secondary structure of human insulin-like growth factor-I (IGF-I) in solution.

Human insulin-like growth factor-I (IGF-I) was studied by two-dimensional 1H-NMR spectroscopy. Resonance assignments were obtained for all the backbone protons and almost all of the sidechain protons of the total 70 amino acid residues, using sequence-specific assignment procedures. The secondary structure elements of human IGF-I were identified by investigation of the sequential and medium range NOEs as a preliminary step in determining the three-dimensional structure of this protein by means of distance geometry calculations. The typical NOEs of d alpha beta(i,i + 3) and d alpha N(i,i + 3), as well as the successive strong NOEs of dNN connectivities and slowly exchanging amide protons confirmed the presence of three helical segments corresponding to the sequence regions, Ala8-Cys18, Gly42-Cys48, and Leu54-Cys61, and the existence of a beta-turn in the Gly19-Gly22 region. Our results definitely indicate that the secondary structure of human IGF-I in solution is consistent with that of insulin in the crystalline state.

Amino Acid Sequence↗
PubMed1992

Swimming changes vascular fatty acid composition and prostanoid generation of rats.

To define the effects of physical activity on vascular fatty acid composition and prostanoid generation, spontaneously hypertensive and normotensive rats were made to swim at 34-35 degrees C for 5-7 wk. Fatty acids were determined by gas chromatography and prostanoids by high-performance liquid chromatography and electrochemical detection. A characteristic feature of swimming rats was a markedly reduced linoleic acid content in the iliac artery and the aorta; in normotensive swimming rats stearic acid and arachidonic acid contents were increased. These changes could not be attributed to a heat loss during swimming or to depressed growth characteristics. A chemical sympathectomy using guanethidine (60 mg/kg body wt daily) did not prevent the alterations in fatty acid composition. A higher arachidonic acid content was correlated with an increased generation of 6-ketoprostaglandin F1 alpha in the aorta of untreated rats and sympathectomized rats. It is concluded that swimming can alter the vascular fatty acid composition in a manner which results in an increased potential for prostacyclin production.

Animals↗
PubMed1992

[The effect of etoposide on influx and efflux of cytosine arabinoside in P388 murine leukemic cells].

We studied the effects of etoposide on the influx, intracellular accumulation and efflux of ara-C in P388 leukemic cells. Etoposide inhibited the active influx of ara-C in a dose dependent manner, and the inhibition was reversible. Etoposide also affected the intracellular accumulation of ara-C, though its inhibitory effect for the intracellular accumulation was weaker than that for the influx of ara-C. It was also shown that etoposide inhibited the active efflux of ara-C. Furthermore, etoposide inhibited the active transport of ara-C bidirectionally but the insensitive route of etoposide existed especially at high concentration of ara-C. The effect of inhibition of the transport of ara-C on the accumulation of ara-C was more significant at lower concentration of ara-C. Judging from the drug concentrations used in this study, an interaction between etoposide and ara-C could occur in the clinical treatment.

Animals↗
PubMed1992

Effects of removal of chicks from hens on concentrations of prolactin, luteinizing hormone and oestradiol in plasma of brooding Gifujidori hens.

Gifujidori hens were allowed to repeat a breeding cycle in one season. In the first breeding cycle the duration of the brooding (raising chicks) stage was limited to 3 weeks, whereas in the second breeding cycle it was limited to 1 week by removing all chicks from mother hens. In the first breeding cycle, plasma prolactin (PRL) was high during the incubation period, but rapidly decreased on the day of hatching and reached minimum values about 1 week after hatching. In contrast, plasma luteinizing hormone (LH) concentrations were low during the incubation period, but after hatching they gradually increased and reached peak values immediately after removal of chicks. Concentrations of oestradiol in plasma were low in the incubation and brooding stages but increased significantly immediately after removal of chicks. In the second breeding cycle, changes in PRL and LH concentrations were similar to those observed in the first breeding cycle except that even greater increases in plasma LH and oestradiol concentrations were observed one week after hatching when the chicks were removed. These results suggest that coexistence of newly hatched chicks may suppress LH secretion from the pituitary of the hen in the natural breeding cycle.

Animals↗
PubMed1992

[Adult T-cell leukemia with various pulmonary complications].

A 59-year-old male, born in Wakayama prefecture, was admitted to our hospital because of cervical lymph node swelling, huge mass lesions in both liver and head of the pancreas, and multiple nodular shadows in the left lung. Lymph node biopsy revealed a necrotic lesion containing tuberculous bacilli with no epithelioid cells or giant cells. Adult T-cell leukemia (ATL) was diagnosed by the presence of atypical lymphocytes with a convoluted nucleus and positive anti-ATL antibody. During successful treatment of Mycobacterium tuberculosis with ethambutol, isoniazid and rifampicin, ATL transformed to the blastic phase. The new pulmonary infiltrates improved after treatment with both combination chemotherapy for ATL and antibiotics. However, new infiltrative shadows appeared in both lungs, and were resistant to treatment and the patient died of acute respiratory failure. Histological examination of the lung at autopsy showed interstitial fibrosis with infiltration of leukemic cells and cytomegalovirus infection.

Cytomegalovirus Infections↗
PubMed1992

[Malignant histiocytosis associated with central neurological symptoms and cerebrospinal fluid involvement].

A 53-year-old woman was admitted with fever and general fatigue in December, 1988. A diagnosis of malignant histiocytosis (MH) was made based on her high level of LDH, thrombocytopenia, mild splenomegaly without systemic lymphadenopathy. There was also bone marrow infiltration large atypical cells and erythro-phagocytosis. VEPA therapy resulted in complete remission. Visual disturbance and left lagophthalmos were recognized in March 1990. These signs indicated central nervous system (CNS) relapse which disappeared after intrathecal methotrexate injection. The same symptoms and signs appeared after another, 5 months. Tumor cells were found not only in the central spinal fluid but also in bone marrow. CNS and bone marrow recurrence were treated with intrathecal methotrexate injection VEPA therapy and cranial irradiation. We diagnosed this case as MH, based on the clinical features which did not include systemic lymphadenopathy and laboratory findings although TcR-gamma rearrangement was observed in bone marrow cells. Only one case of CNS infiltration diagnosed when alive has previously been reported in Japan. We report here a very rare case in which by medical treatment CNS infiltrations was improved twice.

Facial Nerve Diseases↗
PubMed1992

[Further evaluation of GPIb binding domain of vWf by synthetic peptides].

We have already demonstrated that the GPIb binding domain of vWf resided at the regions corresponding to residues 474-488(G10) and 694-708(D5). Moreover, conformational change of vWf was suggested to be important for binding to GPIb. The effect of newly synthetized peptide combining G10 and D5 with lysin(G10-D5) on vWf binding to GPIb and platelet aggregation was studied. All synthetic peptides inhibited both vWf binding to GPIb, ristocetin-induced platelet aggregation and asialo vWf-induced platelet aggregation. G10-D5 possessed the most potent inhibitory activity in the interaction of vWf with GPIb. Only G10-D5 reacted with NMC-4 which recognized the epitope in appropriate conformation of vWf. These results indicate that G10-D5 retains some conformational structure and might be a good tool for anti-thrombotic agent.

Humans↗
PubMed1992

[A case of middle lobar bulla associated with severe bronchial asthma].

We experienced a case of middle lobar bulla associated with severe bronchial asthma. Bulla occurs favoritely at apical area and S6, and middle lobar bulla which is very rare has been reported to cause higher ventilatory disorder compared with superior lobar bulla, when it becomes giant. The pathogenesis of the present middle lobar bulla remains unknown, but steroid administration to bronchial asthma may possibly have influenced pleura and/or lung parenchyma. We would like to make its further observation, paying attention to its possible recurrence and its occurrence at other sites.

Adult↗
PubMed1991

Characterization of the uptake of adenosine by cultured rat hippocampal cells and inhibition of the uptake by xanthine derivatives.

Hippocampal cells were cultured in 24-well culture plates with enriched populations of neuron or glial cells. The [3H]adenosine uptake by 7-10-day cultures of these cells was dependent on temperature, but independent of extracellular Na+. The uptake of adenosine (10 microM) for 15 s was greatly blocked by addition of 100 microM dipyridamole, 50-200 microM propentofylline or 50 microM of 2-chloroadenosine or nitrobenzylthioinosine in both cells and by 100 microM pentoxifylline in neuron. Either caffeine or theophylline (50 microM each) had no effect on the uptake by these cells. Inhibition of the adenosine uptake by propentofylline was demonstrated to be competitive in both cells.

2-Chloroadenosine↗
PubMed1991

Determination of a guanosine-malonaldehyde adduct in urine by high-performance liquid chromatography with a thiobarbituric acid reaction detector.

A new method for the determination of a guanosine-malonaldehyde adduct, beta-D-ribofuranosylpyrimido[1,2-a]purin-10(3H)-one (GMA), in rat and human urine is described. The method involves rapid pretreatment using, in sequence, polyamide, ion-exchange and reversed-phase cartridges; determination is by means of high-performance liquid chromatography with a thiobarbituric acid reactor in series with a fluorescence detector. This device can quantitatively determine the adduct at the sub-picomole level. This rapid, selective and sensitive method is suitable for the determination of guanine-malonaldehyde adducts in biological samples, such as human and rat urine. A semi-preparative method for the extraction and purification of these adducts from rat urine and for their identification by mass spectrometry and high-performance liquid chromatography with ultraviolet detection is also reported.

Animals↗
PubMed1991

Novel effect of cyclicization of the Arg-Gly-Asp-containing peptide on vitronectin binding to platelets.

Vitronectin is one of the glycoproteins that mediate cell adhesion and spreading of a variety of cells through the RGD(S) sequence. Vitronectin is demonstrated to bind to glycoprotein IIb-IIIa and play a role in platelet aggregation. Synthetic peptides containing the RGD(S) sequence can inhibit vitronectin binding to platelets, but the affinity of these peptides is less than 1/100th that of native vitronectin. The present study thus examined the ability of modified RGD(S)-containing peptide to inhibit vitronectin binding to thrombin-stimulated platelets. The cyclicization of GRGDSPA peptide was done by the linkage of NH2-terminal glycin and the COOH-terminal alanin. The circular dichroism spectrum of cyclic GRGDSPA peptide only showed negative minimum at approximately 220 nm, but those of other linear peptides such as GRGDSPA and GRGESPA had no effect. This result indicated that only the cyclic GRGDSPA peptide retained some conformational structure to restrict its flexibility. Inhibition experiments revealed that the affinities of the ligands for the receptor decreased in the order of vitronectin = fibronectin = fibrinogen = von Willebrand factor (vWF) greater than cyclic GRGDSPA peptide greater than GRGDSPA peptide. GRGESPA peptide had no effect. These results demonstrate that the conformational structure of the RGD(S) sequence plays the important role for the affinity of vitronectin binding to activated platelets and the increased affinity of the modified peptide is a prerequisite for the potential antithrombotic use.

Amino Acid Sequence↗
PubMed1991

The effect of 1-hydroxyvitamin D3 for prolongation of leukemic transformation-free survival in myelodysplastic syndromes.

Leukemic transformation (LT) free survival was studied in 30 patients with myelodysplastic syndromes (MDS). In 15 cases, 4-6 micrograms/day of 1-hydroxyvitamin D3 was administered, for a median duration of 17 months (D-group), other subjects had no therapy (N group). LT free survival of the D group had significant advantage over that of the N group according to the Kaplan-Meier method (P less than 0.001). In addition, 7 cases in the N group developed acute leukemia, in contrast to only one in the D group (P less than 0.05). These results suggest that oral administration of 1-hydroxyvitamin D3 prevents the progression of MDS to overt leukemia under the effect of differentiation capacity from blasts to monocytes.

Acute Disease↗
PubMed1991

Assignments of 1H-15N magnetic resonances and identification of secondary structure elements of the lambda-cro repressor.

The assignments of 1H-15N magnetic resonances of the lambda-cro repressor are presented. Individual 15N-amino acids were incorporated into the protein, or it was uniformly labeled with 15N. For the 13C-15N double-labeling experiments, 13C-amino acids were incorporated into the uniformly 15N-labeled protein. All the amide 1H-15N resonances could be assigned with such specific labeling, and sequential connectivities obtained by two-dimensional (2D) 1H-15N reverse correlation spectroscopies and three-dimensional (3D) 1H/15N NOESY-HMQC spectroscopy. Conventional 2D 1H-1H correlation spectroscopies were applied to the assignment of the side-chain protons. Some of the 1H resonance assignments are inconsistent with those previously reported [Weber, P.L., Wemmer, D.E. and Reid, B.R. (1985) Biochemistry, 24, 4553-4562]. The sequential NOE connectivities and H-D exchange rates indicate several elements of the secondary structure, including alpha-helices consisting of residues 8-15, 19-25 and 28-37, and three extended strands consisting of residues 4-7, 39-45 and 49-55. Based on several long-range NOEs, the three extended strands could be combined to form an antiparallel beta-sheet. The amide proton resonances of the C-terminal residues except Ala66 (residues 60-65) were hardly observed at neutral pH, indicating that the arm is flexible. The identified secondary structure elements in solution show good agreement with those in the crystal structure of the cro protein [Anderson, W.F., Ohlendorf, D.H., Takeda, Y. and Matthews, B.W. (1981) Nature, 290, 754-758].

Amino Acid Sequence↗
PubMed1991

Decreased DNA polymerase sensitivity to 1-beta-D-arabinofuranosylcytosine 5'-triphosphate in P388 murine leukemic cells resistant to vincristine.

P388 murine leukemic cells 28.6-fold resistant to vincristine were cross-resistant to doxorubicin and etoposide. Although the intracellular ara-CTP in P388 murine leukemic cells resistant to vincristine (P388/VCR) was significantly higher than that in the parent cells, the cytotoxic effect of ara-C was not significantly different between the parent and resistant cells. Therefore, we investigated the DNA synthesis in P388/VCR and its parent cell line using the permeable cell system. The DNA synthesis in P388/VCR cells was less sensitive to ara-CTP and dTTP than that in P388 parent cells. These results suggested that the characteristics of DNA polymerase in P388/VCR cells might change when the cells developed multiple drug resistance.

Animals↗