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Biomedical subjects

Y Oh

Publications and source records attributed to Y Oh.

At least 145 records · Page 8Linked to original sources
PubMed1993

Bone marrow transplantation for Fanconi anemia. Adjustment of the dose of cyclophosphamide for preconditioning.

PURPOSE: Five patients with Fanconi anemia have been treated by bone marrow transplantation. PATIENTS AND METHODS: They were conditioned with cyclophosphamide (CY) (20-150 mg/kg), antilymphocyte globulin, and thoracoabdominal irradiation (4-6 Gy). The dose of CY for preconditioning was adjusted individually, based on the in vitro effect of CY metabolites on the chromosomes of patients with Fanconi anemia. Four patients received marrow from human leukocyte antigen (HLA)-identical siblings, and one received marrow from his HLA phenotypically identical father. RESULTS: All patients achieved engraftment, and acute graft-versus-host disease (GVHD) grade II or more was not observed. Three developed chronic GVHD. All patients are surviving 2-5 years after grafting, with hematological improvement. CONCLUSIONS: These results indicate that the individual dose adjustment of CY used for preconditioning may prevent graft failure and severe acute GVHD.

Anemia, Aplastic↗
PubMed1993

Indications and technique for reopening closed filtering blebs using the Nd:YAG laser--a review and case series.

We reviewed the results of Nd:YAG laser treatment used with gonioscopy to reopen the internal sclerostomy in 10 consecutive patients with failing filtering blebs in whom the sclerostomy had become occluded internally with a membrane or iris after filtering surgery. Sixteen to 50 applications of 6- to 6.9-millijoules Nd:YAG laser irradiation were directed to the internal sclerostomy site. In 6 of the 10 patients, filtration was successfully reestablished, initially reducing the mean intraocular pressure (IOP) from 26.5 mm Hg (range, 20 to 40 mm Hg) to 8.6 mm Hg (range, 5 to 16 mm Hg), with an average IOP of 13.5 mm Hg at 7 months after the laser treatment. Nine of the patients were on significantly fewer glaucoma medications. We conclude that the YAG laser can be successfully used to reopen the fistula by the internal approach in carefully-selected patients who previously have had well-established filtering blebs. Identification of these suitable candidates involves careful gonioscopy.

Adult↗
PubMed1992

Biochemical evidence for the presence of an amiloride binding protein in adult alveolar type II pneumocytes.

An amiloride binding protein in adult rat and rabbit alveolar type II (ATII) cells was characterized using three different antibodies against epithelial Na+ channel proteins. We found that 1) polyclonal antibodies raised against epithelial Na+ channel proteins from bovine kidney cross-react with a 135-kDa protein in ATII membrane vesicles on Western blots; 2) using the photoreactive amiloride analog, 2'-methoxy-5'-nitrobenzamil (NMBA), in combination with anti-amiloride antibodies, we found that NMBA specifically labeled the same M(r) protein; and 3) monoclonal anti-idiotypic antibodies directed against anti-amiloride antibodies also recognized this same M(r) protein on Western blots. We also demonstrated a low benzamil affinity binding site (apparent Kd = 370 nM) in rabbit ATII cell membranes and both high and low benzamil affinity binding sites (apparent Kd = 6 nM and 230 nM) in bovine kidney membranes using [3H]Br-benzamil as a ligand. Pharmacological inhibitory profiles for displacing bound [3H]Br-benzamil were also different between ATII cells and bovine kidneys. These observations indicate that adult ATII pneumocytes express a population of epithelial Na+ channels having a low affinity to benzamil and amiloride and a pharmacological inhibitory profile different from that in bovine kidney.

Affinity Labels↗
PubMed1992

The insulin-like growth factor II (IGF-II)/mannose 6-phosphate receptor mediates IGF-II-induced motility in human rhabdomyosarcoma cells.

Insulin-like growth factor-II (IGF-II) is an autocrine growth and motility factor for human rhabdomyosarcoma. It interacts with three different receptors: the IGF-I, the IGF-II, and the insulin receptor. A specific function of the IGF-II receptor in mediating IGF-II responses has not been defined. In this report we investigate the mechanism of IGF-II-mediated motility in rhabdomyosarcoma cells. We demonstrate that IGF-II and [Leu27]IGF-II, an analog selective for the IGF-II receptor, stimulate motility at concentrations in which they interact only with their own receptor. An antibody that blocks the IGF-I receptor does not inhibit either peptide activity, while an antibody specific for the IGF-II receptor suppresses the IGF-II-induced motility. This antibody does not interfere with rhabdomyosarcoma cell proliferation. We conclude that in rhabdomyosarcoma cells IGF-II stimulates two different responses mediated by distinct receptors: 1) a mitogenic response through the type I receptor and 2) a motility response through the type II receptor.

Affinity Labels↗
PubMed1992

Local and systemic influenza haemagglutinin-specific antibody responses following aerosol and subcutaneous administration of inactivated split influenza vaccine.

An easily administered and safe vaccine is required to produce the herd immunity necessary to control influenza epidemics worldwide. A commercial quadrivalent inactivated split influenza vaccine was administered intranasally in aerosol form to a group of 46 volunteers; other groups were given the same vaccine subcutaneously and saline intranasally. The results show that mucosal stimulation via intranasal vaccination resulted in a marked increase in local HA-specific IgA antibodies, and that this stimulation was necessary for serum HA-specific IgA responses. Serum HA-specific IgA antibody levels can be used as indicators of local antigenic stimulation, providing a method for evaluating potency and antigenicity in humans of intranasal influenza vaccine. This vaccination route shows much promise for the future.

Adult↗
PubMed1992

A simple and sensitive ELISA of antibodies to pertussis antigens.

A precise method for quantifying serum antibody levels to antigens of Bordetella pertussis is required to evaluate pertussis vaccines, to diagnose pertussis infections, and to detect transplacentally transmitted maternal antibodies. The purpose of this paper is to report a rapid, sensitive, easy and standardized ELISA method using polystyrene balls for the assay of serum antibodies against pertussis toxin (PT) and filamentous haemagglutinin (FHA), which are protective antigens of B. pertussis. By the polystyrene ball method, a clear-cut difference was observed between values of pre- and postvaccination serum samples while by the conventional plate method those values overlapped. It was concluded that the PS ball method is one of the most sensitive and simple methods for detecting antibodies against PT and FHA.

Adhesins, Bacterial↗
PubMed1992

Elevation of serum erythropoietin after subtotal parathyroidectomy in chronic haemodialysis patients.

After successful subtotal parathyroidectomy (PTX) in 10 chronic haemodialysis patients, significant elevation of Epo was observed, from 48.4 +/- 17.8 mU/ml(M +/- SEM) at preoperative state to 103.3 +/- 34.7 mU/ml at 6 h and 163.4 +/- 50.2 mU/ml at 12 h after PTX. Significant reductions in both PTH-m and ionized calcium (iCa) were confirmed. Since Epo did not increase in the cases with an inadequate PTX and ovariectomy, an abrupt reduction in PTH with a decrease in iCa may play some role in the elevation of Epo.

Adult↗
PubMed1992

Immunocytochemical and functional characterization of Na+ conductance in adult alveolar pneumocytes.

The purpose of this study was to document the existence, assess the spatial localization, and characterize some of the transport properties of proteins antigenically related to epithelial Na+ channels in freshly isolated rabbit and rat alveolar type II (ATII) cells. ATII cells, isolated by elastase digestion of lung tissue and purified by density-gradient centrifugation, were incubated with polyclonal antibodies raised against Na+ channel protein purified from beef kidney papilla (NaAb), followed by a secondary antibody (goat antirabbit immunoglobulin G conjugated to fluorescein isothiocyanate). Rat ATII cells exhibited specific staining with NaAb at the level of the plasma membrane, which, in most cells, colocalized with that of the lectin Maclura pomiferra agglutinin, an apical surface marker. In Western blots, NaAb specifically recognized a 135 +/- 10-kDa protein in rat ATII membrane vesicles. When patch clamped in the whole cell mode using symmetrical solutions (150 mM Na+ glutamate), ATII cells exhibited outwardly rectified Na+ currents that were diminished by amiloride (10-100 microM) instilled into the bath solution. Ion substitution studies showed that the conductive pathways were three times more permeable to Na+ than K+. Amiloride, benzamil, and 5-(N-ethyl-N-isopropyl)-2',4'-amiloride were equally effective in diminishing 22Na+ flux into rabbit and rat ATII cells (45% inhibition at 100 microM, with IC50 of approximately 1 microM for all inhibitors). Tetraethylammonium chloride (10 mM) or BaCl2 (2 mM), well-known K+ channel blockers, had no effect on 22Na+ uptake. These results indicate that ATII cells express an amiloride-sensitive Na+ conductance, probably a channel, with a lower affinity for amiloride and its structural analogues than the well-established amiloride-sensitive Na+ channels found in bovine renal papila and cultured amphibian A6 kidney cells.

Amiloride↗
PubMed1992

Non-receptor mediated, post-transcriptional regulation of insulin-like growth factor binding protein (IGFBP)-3 in Hs578T human breast cancer cells.

Hs578T human breast cancer cells secrete insulin-like growth factor binding protein 3 (IGFBP-3) as the major BP species. In addition, cell surface-associated IGFBP-3 is demonstrable by the use of cell monolayer affinity cross-linking or immunoperoxidase staining of the cell surface with a specific polyclonal anti-human IGFBP-3 antibody (alpha IGFBP-3 gamma 1). In this study, we have demonstrated that regulation of Hs578T IGFBP-3 by IGF peptides is specific, non-receptor mediated, and post-translational by showing: 1) dose-dependent increase of IGFBP-3 in conditioned media (CM) following addition of IGF-I and -II (maximum 13 fold increase at 100 ng/ml), but not by insulin up to 1 mg/ml; 2) no change in CM IGFBP-3 level by [Gln3,Ala4,Tyr15,Leu16] IGF-I, which has decreased affinity for IGFBPs; 3) no change in IGFBP-3 mRNA following addition of IGFs; 4) release of cell surface-associated IGFBP-3 into CM by the addition of IGFs, but not by [Gln3,Ala4,Tyr15,Leu16]IGF-I. These studies demonstrate that IGF peptides regulate CM concentrations of IGFBP-3 through non-receptor mediated dissociation of cell surface-associated IGFBP-3.

Blotting, Northern↗
PubMed1991

Altered affinity of insulin-like growth factor II (IGF-II) for receptors and IGF-binding proteins, resulting from limited modifications of the IGF-II molecule.

The binding affinities of seven analogues of recombinant human insulin-like growth factor II (hIGF-II) were characterized for the IGF type-I and type-II receptors and insulin receptors, as well as for IGF-binding protein (IGFBP)-1, IGFBP-2, IGFPB-3 and human serum IGFBPs. A switch of two of the three cysteine bridges in hIGF-II, 9-47 and 46-51 to 9-46 and 47-51, severely impaired the binding of this analogue to all receptors and to the IGFBPs. The affinities for the IGF type-I receptor and the IGFBPs were decreased over 100-fold, while the binding to the insulin receptor and the IGF type-II receptor was less affected, with a 6-10-fold decrease in affinity. Slight modifications of the N-terminus had only minor effects upon the binding of hIGF-II to the IGFBPs or to the receptors. Deletion of both the N-terminal amino acid and the two C-terminal amino acids resulted in moderate decreases in affinity, with a 60% decrease in affinity for IGFBP-1 and the IGF type-I receptor. Acetylation of the N-terminus of Ala1 and the epsilon-nitrogen of Lys65 decreased the affinity, by 60-90%, of hIGF-II for all of the IGFBPs and receptors. The experiments involving acetylation of IGF-II or switching of its cysteine bridges indicated that these modifications (no substitution, deletion or addition of any of the 67 amino acids of hIGF-II) may lead to a severe impairment of the binding affinity of IGF-II for both the IGFBPs and the receptors. Acetylation of the epsilon-nitrogen of Lys65, which causes a charge change, or alteration of the three-dimensional structure, as shown by the cysteine bridge switch, lead to a severe impairment of the binding affinity for the binding proteins and for the receptors. In general, care should be taken with the synthesis of analogues and the interpretation of resulting binding data, since affinity alterations ascribed to amino acid changes may instead be caused by alterations of the charge or the three-dimensional structure of the protein.

Amino Acid Sequence↗
PubMed1991

Dose dependency of germanium-dioxide-induced nephrotoxicity in rats.

The dose dependency of germanium dioxide(GeO2)-induced nephrotoxicity was investigated experimentally in rat groups orally treated with high (150 mg/kg/day), moderate (75 mg/kg/day), or low (37.5 mg/kg/day) doses of GeO2, and in an untreated group. Renal dysfunction, indicated by the increase of blood urea nitrogen and the decrease of creatinine clearance, and systemic toxicity by weight loss, anemia, and hypoproteinemia were more apparent in rats treated with higher dose of GeO2. Urinalysis including daily urinary protein excretion did not reveal any abnormalities in any of the groups. Urinary excretion and renal-tissue content of Ge were significantly elevated in the group of the higher dose of GeO2. Light microscopically, vacuolar degeneration and depositions of granules positive for periodic acid-Schiff in distal tubules were predominant in the higher-dose group of GeO2. The present study demonstrates that GeO2-induced nephrotoxicity develops dose dependently.

Animals↗
PubMed1991

[Leu27] insulin-like growth factor II is highly selective for the type-II IGF receptor in binding, cross-linking and thymidine incorporation experiments.

Insulin-like growth factor-II (IGF-II) is able to interact with three different receptors: the type-I and type-II IGF receptors, and the insulin receptor, although with a lower affinity. This cross reactivity obscures the mechanisms via which the biological activities of IGF-II are mediated. We have synthesized an IGF-II analog, [Leu27]IGF-II, that is highly selective for the type-II IGF receptor. Receptor binding experiments demonstrate a high affinity for the type-II IGF receptor, analogous to synthetic (syn) and recombinant (rec) IGF-II, but no affinity for the type-I IGF and the insulin receptor at concentrations up to 50 and 200 ng/ml, respectively. The lack of affinity for these two receptors is confirmed by biological studies which demonstrated that this analog, in contrast with synIGF-II, did not stimulate [3H]thymidine incorporation in Balb/c 3T3 cells. [Leu27]IGF-II opens new ways to identify which actions of IGF-II are mediated via the type-II receptor and which are due to cross reactivity with the type-I IGF or the insulin receptor.

Animals↗