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Biomedical subjects

K Ohta

Publications and source records attributed to K Ohta.

At least 631 records · Page 35Linked to original sources
PubMed1990

[A clinical observation of epithelial pearls in newborn babies. 1. Appearances and continuous changes].

The purpose of this study was to learn about the appearances and continuous changes of epithelial pearls. The study group comprised 517 normal newborn babies (261 males and 256 females) aged from 24 hours of birth to 22 days. Furthermore, we made the follow-up survey on the continuous changes in 21 newborn babies at the Niigata University Medical Hospital. The following results were obtained by analyses of the examination of the oral cavity in newborn babies during the period from December 1987 to December 1988. 1) Yellow-white in colour, pinhead shaped, 1-3 mm diameter in size, elevated firm nodules were seen in the alveolar ridge mucosa of the maxilla, mandible and/or palate. The average number of epithelial pearls was 1-3. 2) The number of newborn babies who had epithelial pearls was 226 (109 males and 117 females) out of 517 (43.7%). There was no predominant sex preference. 3) The most common location was the maxillary alveolar mucosa (309, 72.5%) followed by the median palatine raphe (97, 22.8%) and mandibular alveolar mucosa (20, 4.7%). 4) In this study, the relationship between the environmental factors of newborn babies in the prenatal and postnatal periods (mother's age, the course of the pregnancy, trouble at birth, the period of pregnancy, baby weight at birth etc.) and the rate of appearances of the epithelial pearls was examined. These factors showed no significant relationships. 5) Based on the findings of the clinical investigation of epithelial pearls during neonatal period, some cases were found and involved thickening and/or thinning in changes in the quantity and number.

Dental Enamel↗
PubMed1990

[Phase I study of YNK01 (1-beta-D-arabinofuranosylcytosine-5'-stearylphosphate)].

Phase I study of YNK01 (1-beta-D-arabinofuranosylcytosine-5'-stearylphosphate), a derivative of cytosine arabinoside (Ara-C), was conducted by cooperative study groups between January 1986 and June 1987. The dosage for the single and 5-day oral administration ranged 50 to 1,200 and 100 to 900 mg/body/day, respectively. The main adverse effects were myelo-suppression and gastrointestinal toxicities such as nausea, vomiting, anorexia and diarrhea. In the single administration, the maximum tolerated dose (MTD) could not be determined, however, in the 5-day schedule MTD was considered to be 700 to 900 mg/body/day, and the dose limiting factor to be thrombocytopenia. After the single administration (800 mg/body/day) of YNK01, the plasma concentration of Ara-C, an active metabolite of YNK01, was 3.43 ng/ml (Cmax) at 24 hrs. and 0.82 ng/ml at 72 hrs. During the 5-day administration for 300 mg/body/day and 500 mg/body/day, the Ara-C concentration changed from 2.3 to 4.1 ng/ml, and from 1.5 to 11.9 ng/ml respectively, and sustained almost the same concentration as to during the administration period until the 2nd day after the completion of the administration.

Administration, Oral↗
PubMed1990

Enzyme immunoassay for measuring antibodies against skeletal muscle in patients with myasthenia gravis.

We developed a highly sensitive enzyme immunoassay (EIA) for measuring IgG and IgM antibodies against human skeletal muscle (SM) component and tested sera from 100 patients with myasthenia gravis (MG), 59 with thymoma and 41 without thymoma. We found that the frequency of anti-SM IgG antibodies was significantly higher in MG patients with (81%) than without (37%) thymoma. The titers of the anti-SM IgG antibodies measured by EIA correlated well with those measured by RIA (r = 0.81, P less than 0.01). We also found that 12% of the myasthenic patients with thymoma and 15% without it had anti-SM IgM antibodies. There was no correlation between the titers of the IgG and IgM antibodies. Our EIA provides a measure of anti-SM antibodies that is of comparable sensitivity to that of RIA.

Antibodies, Anti-Idiotypic↗
PubMed1990

Improved radioassay of anti-acetylcholine receptor antibody: application for the detection of extremely low antibody titers in sera from patients with myasthenia gravis.

We examined sera from 113 patients with myasthenia gravis (MG). Most of the patients with ocular MG without thymoma and 15% of the patients with generalized MG had immunoprecipitation (IP) titers of anti-acetylcholine receptor (anti-AChR) antibodies within the normal range for healthy subjects. We developed a highly sensitive radioassay using Staphylococcus aureus cells, and re-examined the 86 serum samples that had negative titers by IP. Using the radioassay, we detected anti-AChR antibodies in 27 (31%) of these myasthenic sera, of which 19 were from ocular MG patients without thymoma. By combining the standard IP assay and our new radioassay, we increased to 50% the overall percent positivity of detecting nonblocking-type antibodies in ocular MG patients without thymoma. We detected no anti-AChR antibodies in nearly all patients with various immunological and neurological diseases other than MG, and in all the healthy controls. The data for these sera indicate that in some cases the standard IP assay gives false-negative reactions. Thus, use of the more sensitive radioassay is preferable for accuracy.

Acetylcholine↗
PubMed1990

[Juvenile Crow-Fukase syndrome with response to bolus of methylprednisolone after failure of treatment by plasma exchange].

A 20-year-old woman was hospitalized because of abdominal distention. She had developed facial edema about one year earlier, and recently amenorrhea and red verrucae on the chest and abdomen. Neurological examination disclosed hypesthesia, paresthesia, and diminished tendon reflexes in the arms and legs. The level of serum immunoglobulin A (IgA) was elevated and an M protein was detected. Examination of the bone marrow disclosed abnormal increase in plasma cells. Results of glucose tolerance test were mildly abnormal. The patient was diagnosed as Crow-Fukase syndrome. Plasma exchange was done four times and melphalan was given orally for two weeks, but the level of serum IgA increased further. Then one bolus injection of methylprednisolone decreased the serum IgA with improvement in other signs. The disorder is now controlled satisfactory with a low dose of prednisolone.

Adult↗
PubMed1990

Effect of glycerol on the hemodynamics of acutely induced ischemic area in the cerebral cortex of cats.

The effect of glycerol on the hemodynamics of ischemic areas of the brain was examined. Employing a photoelectric apparatus, the CBV (vol%), mean transit time of blood(s), and CBF (ml/100 g/min) in the cortex of the left ectosylvian gyrus were determined in 16 anesthetized cats before, at 1 hr, and at 2 hr after left MCA occlusion. In 10 cats, 10% glycerol in 5% fructose saline was intravenously administered at a speed of 5 ml/kg/hr at 1 hr after MCA occlusion. The other animals served as the control. In the group given glycerol, the relation between the values of CBF at 1 hr after MCA occlusion (X) and those at 2 hr after MCA occlusion (Y) was curvilinear and could be expressed by the regression curve, Y = 0.04X2 - 0.26X + 7.68 (R2 = 0.86). In the control group without glycerol, however, a linear relation expressed by the equation, Y = 0.76X + 5.96 (R2 = 0.94), was obtained. Comparison between the two relations indicated that glycerol improved the hemodynamics in the mild ischemic area with a relatively higher CBF. Severely ischemic areas showed no improvement.

Animals↗
PubMed1990

[Phase I clinical study of CPT-11. Research group of CPT-11].

CPT-11 is a new derivative of Camptothecin. Phase I clinical study of single administration with CPT-11 was carried out by a cooperative study group. Starting from 50 mg/m2 (n), dose was escalated to 350 mg/m2 (7n). Dose limiting factor was found to be a decrease in WBC counts (especially in neutrophils), and MTD was presumed to be 250 mg/m2 or more. Nadir of WBC counts was observed after about a week, and it took 2-3 weeks for recovery. The decrease in platelet number and hemoglobin content was mild. Other side effects included G-I toxicities, alopecia, etc. However, no toxic effects on the heart, kidney, lung were observed. SN-38, main metabolite of CPT-11, was observed in blood, and excreted rapidly. Anticancer effects were suggested with dose of 165 mg/m2 or more against colon cancer, gastric sarcoma, melanoma and lung cancer. It is suggested that the optimal dose schedule for an early Phase II study is 200 mg/m2 every 3-4 weeks. However, not only leukopenia but also marked G-I toxicities being noted in some cases, care should be taken for those side effects.

Adult↗
PubMed1989

Effect of endothelin-1 on release of arginine-vasopressin from perifused rat hypothalamus.

Endothelin-1 (ET-1) is an endothelium-derived vasoconstrictor peptide with potent pressor activity. We studied the effect of ET-1 on release of arginine-vasopressin (AVP) from perifused rat hypothalamus. ET-1 (10(-10) to 10(-8) M) significantly stimulated AVP release. The ET-1-induced AVP release was completely blocked in the presence of nicardipine. Our results suggest a possible involvement of ET in the regulation of AVP release.

Animals↗
PubMed1989

Mast cells are important in the development of hypersensitivity pneumonitis. A study with mast-cell-deficient mice.

We have previously reported that C57B1/6 mice develop lung lesions similar to human hypersensitivity pneumonitis (HP) by repeated transnasal administration of Thermoactinomyces vulgaris antigen. Since the HP-like lesions were induced via respiratory route and by the causative antigen in human HP (farmer's lung), it seems that this murine model is useful for investigating the cell-to-cell interactions in human HP. To clarify the involvement of mast cells (MC) in the development of HP, T. vulgaris (90 micrograms/day) was transnasally administered to MC-deficient WBB6F1-W/Wv mice (W/Wv) and their littermates (+/+) five times a wk for 3 wk. When the lungs were examined by scoring pathological findings and lung indexes, HP-like lesions were significantly less severe in W/Wv than in +/+, whose lesions were equivalent to those of C57B1/6. Bone-marrow-derived cultured MC from +/+ mice (98% purity) were obtained by in vitro culture mixed with WEHI-3B-derived conditioned medium which contained IL-3. When these MC were adoptively transferred to W/Wv mice (10(7) cells/mouse), the HP-like lesions in W/Wv mice were enhanced to be as severe as those in +/+. Importantly, significant numbers of MC were found in the lungs of MC-transferred W/Wv mice. These results suggest that MC play an important role in the development of the murine experimental HP.

Alveolitis, Extrinsic Allergic↗
PubMed1989

Secretion of endothelin and related peptides from renal epithelial cell lines.

Using specific radioimmunoassays (RIAs) for endothelin (ET) and big ET, we have studied whether ET and related peptides are secreted from renal epithelial cell lines (LLCPK1 and MDCK) of non-endothelial origin. Dilution curves of extracts of conditioned media from both LLCPK1 and MDCK cell lines were parallel to those of standard porcine (p) ET and big pET in each RIA. Both cell lines incubated in serum-free medium secreted ET- and C-terminal fragment (CTF)-like immunoreactivity (LI) of big ET as a function of time. Reverse-phase HPLC coupled with both RIAs of the extracted media from both cell lines revealed a single component with ET-LI coeluting with pET(1-21) and several components with CTF-LI, one corresponding to the elution position of big pET(1-39), one to its CTF(22-39), and the others eluting earlier than CTF. These data indicate that endothelin and related peptides are synthesized by and secreted from cells other than endothelial cells.

Animals↗
PubMed1989

Concomitant secretion of big endothelin and its C-terminal fragment from human and bovine endothelial cells.

A specific radioimmunoassay (RIA) for the carboxyl-terminal fragment (CTF) of big porcine endothelin (pET), an intermediate form of pET, was established to characterize big ET-like and its CTF-like immunoreactivity (LI) secreted from cultured bovine and human endothelial cells (EC). The antibody used crossreacted equally with big pET(1-39) and its CTF(22-39), but not with pET(1-21). Serial dilution curves of the culture media from bovine and human EC were parallel to that of standard CTF. Reverse-phase HPLC coupled with RIAs for big ET and ET of the culture media from bovine and human EC revealed essentially the same elution profiles: two major CTF-LI components, one corresponding to big pET(1-39) and the other to its CTF(22-39), in addition to one major ET-LI component corresponding to pET(1-21). The amounts of CTF-LI were almost equal to that of ET-LI on a molar basis. These data suggest that big ET is processed by a putative ET converting enzyme to yield its CTF and the mature ET(1-21) in EC.

Amino Acid Sequence↗
PubMed1989

Purification of cytochrome P-450 from polychlorinated biphenyl-treated crab-eating monkeys: high homology to a form of human cytochrome P-450.

Cytochrome P-450, designated as P-450-MK2, was purified to an electrophoretic homogeneity from polychlorinated biphenyl (PCB)-treated female crab-eating monkeys. P-450-MK2 catalyzed nifedipine and nilvadipine oxidations, at a rate comparable to human P-450-HM1. The N-terminal amino acid sequence of P-450-MK2 was highly homologous to those of P-450-HM1 and NF 25. The antibodies to P-450-HM1 recognized P-450-MK2 and effectively inhibited the activity of testosterone 6 beta-hydroxylase in monkey liver microsomes. These results suggest that a form of cytochrome P-450 corresponding to human P-450-HM1 or P-450NF which belongs to the P450 III gene family is also present in liver microsomes of crab-eating monkeys.

Amino Acid Sequence↗
PubMed1989

Vasoconstrictor-induced heterologous down-regulation of vascular atrial natriuretic peptide receptor.

Long-term (24 h) pretreatment of cultured rat vascular smooth muscle cells with 100 nM angiotensin and 1 microM vasopressin induced a marked reduction of the maximal binding capacity of atrial natriuretic peptide (ANP) receptors in a fashion similar to that induced by phorbol ester. The down-regulation of the receptors induced by vasoconstrictors and phorbol ester was concomitantly associated with an attenuation of ANP-stimulated cGMP accumulation. These data suggest that vasoconstrictor-induced activation of protein kinase C is involved in the mechanism of heterologous down-regulation of vascular ANP receptors.

Angiotensin II↗
PubMed1989

Secretory mechanism of immunoreactive endothelin in cultured bovine endothelial cells.

To elucidate the cellular mechanism by which endothelin (ET) is secreted, we have studied the effects of a variety of vasoactive agents on the secretion of immunoreactive (IR)-ET from cultured bovine endothelial cells (EC). Confluent bovine EC cultured in serum-free medium secreted IR-ET as a function of time. Not only thrombin, but also vasoconstrictive hormones, such as arginine-vasopressin (AVP) and angiotensin (ANG) II, dose-dependently stimulated IR-ET secretion, and these effects were completely abolished by V1-receptor antagonist and [Sar1,Ala8]-ANG II, respectively. Protein kinase C (PKC)-activating phorbol ester and Ca2+ ionophore ionomycin had stimulatory effects on IR-ET secretion, and the combination of both compounds had a synergistic effect. These data suggest that AVP and ANG II, like thrombin, stimulate ET secretion from EC by a mechanism possibly involving receptor-mediated mobilization of intracellular Ca2+ and activation of PKC.

Angiotensin II↗