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Biomedical subjects

S Tsuboi

Publications and source records attributed to S Tsuboi.

At least 127 records · Page 7Linked to original sources
PubMed1989

Therapeutic effect and titers of the specific IgE and IgG antibodies in patients with sea squirt allergy (Hoya asthma) under a long-term hyposensitization with three sea squirt antigens.

Hyposensitization therapy with each of three sea squirt antigens, Gi-rep (molecular weight [MW] 106,000), Ei-M (MW 22,800), and DIIIa (MW 9980), have succeeded in 72%, 90%, and 36% of patients with sea squirt allergy, respectively, within the first year, and the effect has been maintained during subsequent 4-year maintenance therapy. All available sera from some of the hyposensitized patients were also examined for IgE and IgG titers against the most effective therapeutic antigen, Ei-M, and it was revealed that the Ei-M-specific IgG titer increased rapidly in the successfully hyposensitized patients, regardless of the therapeutic antigen used, except for a few patients. Furthermore, the high specific IgG titer, as well as the therapeutic effect, was maintained during the subsequent maintenance therapy. No such increase in the specific IgG titer was detected in all unsuccessfully hyposensitized patients. In contrast, the Ei-M-specific IgE titer was practically unchanged in all allergic patients, independent of the therapy. Therefore, the effect of the hyposensitization therapy was closely dependent on the induction of the specific IgG capable of competing with the specific IgE for a certain asthma-inducing antigen, like DIIIa. The apparently low therapeutic efficiency of DIIIa was attributed to its relatively low immunogenicity to induce the specific IgG.

Allergens↗
PubMed1989

Biosynthesis of nonspecific lipid transfer proteins in germinating castor bean seeds.

The biosynthesis of nonspecific lipid transfer proteins (ns-LTPs) in germinating castor bean (Ricinus communis L.) seeds were investigated. Lipid transfer activities of ns-LTPs in the cotyledons, axis, and endosperm increased with growth after germination. The activity increases were accompanied by increased amounts of ns-LTPs in each tissue, as measured by immunoblot using anti-ns-LTP serum. These results suggest that the ns-LTPs are synthesized de novo in each tissue after germination and not activated from inactive proteins synthesized before germination. Comparison of the immunoblot products in each tissue from 4-day-old seedlings indicate the occurrence of tissue-specific isoforms of ns-LTPs; 9 kilodaltons (major) and 7 kilodaltons (minor) in the cotyledons, and 7 kilodaltons (major) and 9 kilodaltons (minor) in the axis, whereas only the 8-kilodalton ns-LTP is present in the endosperm. In vitro translation from poly(A)(+) RNAs from three tissues of castor bean seedlings and the detection of immunoprecipitated products indicate that translatable mRNAs for ns-LTPs exist in the three tissues a day before the synthesis of ns-LTPs; the translation products, which are 3.5 to 4.0 kilodaltons larger than ns-LTPs, were processed to the mature ns-LTPs. The production of mature ns-LTPs from translatable mRNAs without any delay suggests that gene expression of ns-LTPs in castor bean seedlings is controlled at a step before the formation of translatable mRNAs.

Journal Article↗
PubMed1989

Amino acids and peptides. XXIII. Synthesis of N alpha-protected amino acid 6-chloro-2-pyridyl esters and their evaluation for peptide synthesis.

6-Chloro-2-pyridyl esters (OPyCl) of N alpha-benzyloxycarbonyl and tert-butyloxycarbonylamino acids were synthesized by the N,N'-dicyclohexylcarbodiimide (DCC) method from the acids and 6-chloro-2-hydroxypyridine in dimethylformamide (DMF). The reactivity of the 6-chloro-2-pyridylester with amino group is much higher than that of the corresponding 2-pyridyl ester (OPy) and p-nitrophenyl esters (ONp) in dioxane and DMF, and a peptide bond is formed without acylation at the side chain hydroxyl group of amino acids. Z-Asp(OBzl)-OPyCl reacted with amino acid methyl esters in dioxane to give the corresponding dipeptide without any detectable aspartimide formation.

Amino Acids↗
PubMed1988

Volume flow across the isolated retinal pigment epithelium of cynomolgus monkey eyes.

The retinal pigment epithelium (RPE)-choroid was isolated from cynomolgus monkey eyes with experimental retinal detachments and the volume flow was determined in vitro using Ussing-type chambers. With zero pressure difference across the membrane, retina-to-choroid volume flow was 5.0 microliter/hr/cm2 in eyes with subacute retinal detachments (1-2 weeks). In eyes with chronic retinal detachment (8-20 months), the flow was 7.3 microliter/hr/cm2. Volume flow was not affected by the elimination of ambient bicarbonate. Transepithelial potential difference and resistance were 8.9 mV, retinal side positive, and 339 ohm-cm2, respectively, in chronic retinal detachments. It is concluded that there is a posteriorly directed flow of fluid across the RPE in cynomolgus monkey eyes with chronic retinal detachments.

Animals↗
PubMed1988

Effect of plasma osmolality and intraocular pressure on fluid movement across the blood-retinal barrier.

The inward permeability of the blood-retinal barrier to carboxyfluorescein was determined in monkey eyes with and without rhegmatogenous retinal detachment (RD). In the absence of changes in the diffusional permeability of the retinal pigment epithelium (RPE), inward permeability changes reflect changes in fluid flow across the RPE. Intravenous injection of mannitol resulted in a 15 mosmol/kg increase in plasma osmolality which decreased inward permeability 37% in eyes with RD and 21% in eyes with vitrectomy alone. When the intraocular pressure was raised 20 mm Hg above normal, inward permeability decreased 29% in eyes with RD and 32% in normal eyes. It is concluded that fluid flow across the blood-retinal barrier is influenced by both plasma osmolality and intraocular pressure.

Animals↗
PubMed1987

Significant effects of Z-Gln-Val-Val-OME, common sequences of thiol proteinase inhibitors on thiol proteinases.

The first studies on a series of the small synthetic thiol proteinase inhibitors, conservative common sequences in several thiol proteinase inhibitors, are described. Among the many interesting findings with synthetic thiol proteinase inhibitors was the observation that the most effective analogue, Z-Gln-Val-Val-Ala-Gly-OMe, whose amino and carboxyl groups were protected with Z and OMe, respectively, showed inhibitory activity on papain and cathepsin B and protected papain from egg cystatin, human low-molecular-weight kininogen and T-kininogen-induced inhibition but not from leupeptin-induced inhibition. Moreover, it was revealed that Z-Gln-Val-Val-OMe was the smallest peptide to exhibit a protective effect on papain.

Amino Acid Sequence↗
PubMed1987

A study on the correlation between estrogen receptor, progesterone receptor and tamoxifen binding sites in human breast cancer tissues.

In order to examine the clinical significance of the tamoxifen binding site, correlations between the concentration of the tamoxifen binding site and either the estrogen receptor (ER) or progesterone receptor (PgR) were studied. A saturable high-affinity tamoxifen binding site was detected in human breast cancer tissues. The concentration of the tamoxifen binding sites in 12,000 g supernatant of ER positive tumors was 122.3 +/- 186.8 (mean +/- SD) fmol/mg protein, and that of ER negative tumors was 68.38 +/- 82.97 fmol/mg protein. The concentration of the tamoxifen binding sites in 12,000 g supernatant of PgR positive tumors was 103.7 +/- 137.3 fmol/mg protein, and that in the 12,000 g supernatant of PgR negative tumors was 90.29 +/- 159.0 fmol/mg protein. There was no significant difference between the concentration of the tamoxifen binding sites in the 12,000 g supernatant of ER positive tumors and ER negative tumors, and there was no significant difference between the concentration of the tamoxifen binding sites in the 12,000 g supernatant of PgR positive tumors and PgR negative tumors. The concentration of the tamoxifen binding sites in the cytosol of PgR positive tumors was 90.55 +/- 103.5 fmol/mg protein, and that in the cytosol of PgR negative tumors was 29.13 +/- 42.22 fmol/mg protein. There was a significant difference between them (p less than 0.05). The concentration of tamoxifen binding sites in 12,000 g supernatant had no correlation with the values of ER and PgR. Only the content of tamoxifen binding sites in cytosol, and the PgR value had a significant correlation.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Neoplasms↗
PubMed1987

Amino acids and peptides. XV. Synthesis of Gln-Val-Val-Ala-Gly and derivatives, a common sequence of thiol proteinase inhibitors and their effects on thiol proteinase.

The Gln-Val-Val-Ala-Gly sequence, which occurs frequently in several natural thiol proteinase inhibitors, and derivatives were synthesized by conventional solution methods and their effect on thiol proteinases were examined. The studies led us to the conclusion that certain of these peptides exhibited a weak inhibitory effect on the thiol proteinase, papain. One of them, Z-Gln-Val-Val-Ala-Gly-OMe, showed a protective effect on papain from natural thiol proteinase inhibitor-induced inactivation. The relationship between structure and activity of these derivatives was studied and certain conclusions were derived on possible mode of action of these inhibitors. From these studies, it was concluded that Z-Gln-Val-Val-OMe was the smallest peptide to exhibit some effect on papain.

Amino Acid Sequence↗
PubMed1987

Measurement of the volume flow and hydraulic conductivity across the isolated dog retinal pigment epithelium.

The isolated dog retinal pigment epithelium (RPE)-choroid was gently stretched on the inner surface of a spherical stainless mesh, retinal side upward, and clamped between half-chambers made of Kel-F. The volume flow across the tissue was monitored by the movement of water in capillary tubes connected to both chambers. With zero pressure difference across the RPE-choroid, retina-to-choroid fluid flow was determined to be 6.4 microliters/hr/cm2 (absorption). Removal of HCO-3 from the solution did not affect the fluid flow. However, the flow was reduced 88% in Cl- -free medium, indicating a coupling between water and Cl- absorption. The flow was also inhibited by ouabain (10(-5) M) and furosemide (10(-4) M). Hydraulic conductivity (Lp) of the RPE-choroid was determined to be 0.0126 microliters/min/cm2/mm Hg which places the dog RPE-choroid in the category of a "leaky" epithelium.

Animals↗
PubMed1987

Functional recovery of retinal pigment epithelial damage in experimental retinal detachment.

The integrity of the RPE barrier function in retinal detachment was studied in vitro. The retinal pigment epithelium (RPE)-choroid tissue was isolated from cynomolgus monkey eyes with acute (less than 1 hr), subacute (1-2 weeks), and chronic (8-20 months) retinal detachments, and clamped between Ussing-type chambers. Electrical characteristics and choroid-to-retina permeability to carboxyfluorescein were determined. In the HEPES-buffered bathing solution, transepithelial potential difference and resistance in eyes with acute retinal detachments (0.2 mV and 134 ohm-cm2, respectively) were significantly lower than subacute (7.9 and 350) and chronic (10.4 and 348) retinal detachments. Furthermore, the permeability was increased five-fold in acute retinal detachments with respect to subacute and chronic retinal detachments, indicating a breakdown of the RPE barrier in acute retinal detachment. No statistical difference was found between subacute and chronic retinal detachments. In this animal model, RPE barrier function is destroyed at the onset of retinal detachment, but recovers in a week or two, and is maintained in the chronic stage. Histological examination revealed that RPE recovery was accomplished by RPE proliferation and hyperplasia.

Animals↗
PubMed1987

Acetazolamide effect on the inward permeability of the blood-retinal barrier to carboxyfluorescein.

The inward permeability of the blood-retinal barrier to carboxyfluorescein was determined in 12 cynomolgus monkeys. Probenecid (175 mg/kg), an inhibitor of active outward transport of carboxyfluorescein, did not affect the inward permeability, indicating that the inward permeability is independent of the active outward transport system. However, acetazolamide (20 mg/kg), which causes increased outward fluid movement across the retinal pigment epithelium (RPE), significantly reduced the inward permeability. Thus, inward diffusion of carboxyfluorescein interacts with outward fluid flow across the RPE. Since carboxyfluorescein has low lipid solubility and remains extracellular, it is concluded that the pathway of fluid movement and carboxyfluorescein diffusion across the RPE is paracellular.

Acetazolamide↗
PubMed1987

Permeability of the blood-retinal barrier to carboxyfluorescein in eyes with rhegmatogenous retinal detachment.

Outward and inward permeability of carboxyfluorescein across the blood-retinal barrier were measured fluorophotometrically in seven cynomolgus monkey eyes with experimental rhegmatogenous retinal detachment. Probenecid was used to inhibit outward transport of carboxyfluorescein. The outward permeability was 1.98 +/- 0.31 microliter/min in eyes with retinal detachment and 0.84 +/- 0.15 microliter/min in control eyes with vitrectomy alone (P less than 0.01). The inward permeability, determined separately following intravenous injection, was significantly lower than the outward permeability: 0.14 +/- 0.02 microliter/min for eyes with retinal detachment and 0.04 +/- 0.01 microliter/min for control eyes. Since the outward permeability minus the inward permeability in the presence of probenecid represents that fraction of tracer moving due to fluid flow, it may be concluded that outward flow of fluid across the blood-retinal barrier is a substantial contributor to carboxyfluorescein loss from the vitreous cavity following intravitreal injection.

Animals↗
PubMed1986

Experimental retinal detachment. XI. Furosemide-inhibitable fluid absorption across retinal pigment epithelium in vivo.

Rhegmatogenous retinal detachments were created in one eye of each of six cynomolgus monkeys. Total vitrectomy alone was performed in the fellow eyes. The rate of disappearance of fluorescein sodium injected into the vitreous cavity was measured with kinetic vitreous fluorophotometry. Intravitreal 10(-4)M probenecid was used to inhibit active outward transport of fluorescein. In eyes with retinal detachment, the rate of fluorescein loss from the vitreous cavity was decreased 44% and 22% following intravitreal injection of 10(-4) and 10(-5)M furosemide (Lasix), respectively. Intravitreal 10(-4)M furosemide decreased the rate of fluorescein loss in fellow eyes by 35%. The rate of fluorescein loss via the anterior chamber accounted for only 1% to 8% of the total rate of vitreous fluorescein loss. Thus, it is concluded that intravitreal absorption across the retinal pigment epithelium.

Absorption↗