Biomedical subjects

Y Bai

Publications and source records attributed to Y Bai.

At least 163 records · Page 9Linked to original sources

PubMed1994

Cryopreservation of human bone marrow after purging T-cells or tumor cells.

Bone marrow transplantation (BMT) is a valuable measure for treatment of leukemia. In order to reduce, even to eliminate, the graft versus host disease after allogenic BMT and prevent the reinfusion of tumor cells during autologous BMT, the cryopreservation of human BM after purging T-cells with immunotoxin or purging tumor cells with monoclonal antibody 55 (McAb55) was studied. Results demonstrated that: (1) treatment with McAb55 and rabbit complement (RC) did not affect the GM-CFU of BM, but treatment with immunotoxin slightly decreased the GM-CFU of BM; (2) a freeze-thawing procedure obviously decreased the GM-CFU number of BM, the GM-CFU numbers of frozen BM samples were lower than those of the nonfrozen samples; (3) there were no differences in GM-CFU numbers between normal BM and BM treated with McAb55 and RC when the cooling rate used was the same; (4) there was a negative linear correlation between cooling rates and GM-CFU numbers of BM in the cooling rate range used and the optimal cooling rate for the cryopreservation of normal BM and BM treated with McAb55 and RC or immunotoxin was the same, namely, 0.5 degrees C/min.

Antibodies, Monoclonal↗

PubMed1994

Long-chain fatty acid esters of some norditerpenoid alkaloids.

Several C-8 long-chain fatty acid esters of aconitine-type norditerpenoid alkaloids namely, aconitine, delphinine, delphisine, falconerine-8-acetate, mesaconitine, and pseudaconitine bearing a C-8 acetyl group, have been prepared. Preparation was achieved by heating the alkaloids with the neat fatty acid under vacuum. All the compounds have been fully characterized by physical and spectroscopic data. Identification and characterization of reaction byproducts are also included.

Alkaloids↗

PubMed1994

Molybdenum but not copper counteracts cysteine-induced tibial dyschondroplasia in broiler chicks.

Studies were conducted to evaluate the ability of copper and molybdenum to prevent cysteine-induced tibial dyschondroplasia in broiler chicks. Experiment 1 was a 3 x 3 factorial arrangement of treatments used to investigate the interaction between Cu (0, 150 or 300 mg/kg diet) and Mo (0, 10, or 100 mg/kg diet) on cysteine-induced tibial dyschondroplasia. Molybdenum at both supplemental levels, but not Cu, prevented cysteine-induced tibial dyschondroplasia. In Experiment 2 (a 3 x 3 factorial arrangement of treatments with 0, 5 or 10 g/kg diet of cysteine and 0, 10 or 100 mg/kg diet of Mo), Mo prevented cysteine-induced but not spontaneous tibial dyschondroplasia. Cysteine and Mo did not affect the mechanical properties of the tibiotarsus. In Experiment 3, cysteine (0 or 10 g/kg diet) and Mo (0 or 100 mg/kg diet) were used to study the tissue concentrations of mineral and hepatic sulfite oxidase activity. Supplemental Mo increased Mo concentrations in the plasma and liver. Cysteine prevented these increases; however, cysteine, in the absence of supplemental Mo, did not affect concentrations of Mo in these tissues. Dietary cysteine and/or Mo did not affect tissue levels of Cu. We conclude that Mo prevents cysteine-induced tibial dyschondroplasia and that the induction of tibial dyschondroplasia by cysteine is not related to the Mo and Cu deficiency.

Animals↗

PubMed1994

Permanent ventricular pacing via the great cardiac vein.

Two cases of left ventricular pacing via the great cardiac vein are presented. A 64-year-old female with a mechanical prosthetic tricuspid valve and slow atrial fibrillation had a failed attempt at pacing from the middle cardiac vein. In a 58-year-old male with hypertrophic obstructive cardiomyopathy and bradycardia tachycardia syndrome, transvenous permanent pacing could not be achieved via the right ventricle or middle cardiac vein. In both cases, successful pacing via the great cardiac vein was achieved but with an elevated stimulation threshold. These cases illustrate an alternate transvenous route when difficulties occur using standard ventricular pacing sites.

Atrial Fibrillation↗

PubMed1994

Factors influencing growth plate cartilage turnover.

A number of nutrients and chemicals have now been identified as consistent inducers of tibia dyschondroplasia (TD). Thiram, Antabuse, and fusarochromanone induce TD when fed at 30 to 75 ppm. Cysteine, cystine, homocysteine, and histidine induced TD when fed at .5 to 3% of the diet. Cation: anion imbalances resulting in acidotic diets also induced TD. Even though prevention of TD induced by these chemicals and nutrients has been established, reversal of the spontaneous TD lesion has not been clearly demonstrated. Thus, the etiology of the spontaneous lesion awaits elucidation. These model systems all suggest that TD is the result of decreased growth plate cartilage degradation. Recent work has shown that increased collagen cross-links in the accumulated cartilage, which makes collagen less susceptible to degradation. Cysteine-induced TD seems to decrease growth plate collagenase activity and production. A role of growth plate macrophages in paracrine signaling of collagenase production by chondrocytes has been presented.

Animals↗

PubMed1994

Gene encoding a mammalian epididymal protein.

Polyclonal antibodies raised against a 20 kD epididymal protein (EP20) were used to isolate the cDNA from a human testis lambda gt11 expression library. The nucleotide sequence of the cDNA consisted of 1908 base pairs (bp) containing an open reading frame composed of 1479 bp encoding a polypeptide of 493 amino acid residues. The nucleotide sequence of EP-20 cDNA had 97% identities (282/288) with ESTO 0991 Homo Sapiens cDNA clone HHC M14 in the reverse orientation. The HHC M14 sequence corresponded to a segment in the non-translatable 3'end of EP-20 cDNA. The amino acid sequence of the deduced polypeptide showed no homology with reported polypeptides. The epididymal protein may be involved in sperm maturation and/or capacitation.

Amino Acid Sequence↗

PubMed1994

[The characteristics of two-dimensional and color Doppler ultrasonography in Graves' disease].

Color Doppler flow imaging (CDFI) was performed in 24 patients with Graves' disease, and the results were compared with those from 8 patients with Hashimoto's disease, 6 patients with simple diffuse goiter and 15 normal volunteers. All cases were confirmed by clinical, laboratory tests or by pathology. The CDFI findings of the cases with Graves' disease showed diffuse or localized hypoechoes within the glands and rich flow signals in the hypoechoes, and acceleration of flow velocity and decrease of resistance in the superior thyroid arteries (STA) and arteries within the glands. These appearances were characteristic as compared with the controls. The rate of flow in STA of Graves' disease cases was 8 to 10 times higher than that in the normal volunteers. This study demonstrated that CDFI is convenient, time saving, inexpensive and noninvasive as compared with isotope scan and some other laboratory tests, and can be widely used in the diagnosis of Graves' disease. The pathologic basis of Graves' disease on ultrasonography and its differential diagnosis are discussed.

Adolescent↗

PubMed1994

[Studies on immobilization of suspension cells of peltate yam (Dioscorea zingiberensis C.H. Wright)].

The suspension cells of D. zingiberensis were immobilized with 3% sodium alginate, and then cultured in MS+2, 4-D1.0 + 6-BA 0.1 at 25 degrees C for a long period of time. The culture fluid free from cells was extracted and analyzed by TLC. The result showed that the immobilized cells could secrete the main component of D. zingiberensis--diosgenin, but not consecutively.

Cells, Cultured↗

PubMed1994

[Site-directed mutagenesis of Lac Z gene in Escherichia coli and the kinetic properties of the mutated enzymes].

Glutamic acid at position of 537 of beta-D-galactosidase coded by Lac Z gene was substituted with Aspartic acid, Glutamine and Valine using synthetic oligonucleotide probes. Compared to native enzyme, the kcat values for substrate ONPG were 0.13%, 0.0006% and 0.0035% for Asp-537, Gln-537 and Val-537 mutated enzymes respectively. The Km values were of the same order of magnitude, either native or mutated enzymes. The substrate analog, IPTG was a strong inhibitor of each of the substituted enzymes, as in the case of native enzyme. The transition state analogs, 2-NH2-galactose and L-ribose were almost the same effects for the mutated enzymes as for the normal enzyme. The nucleophili, Azide, did not activate the mutated enzymes as in the case of Glu-461 substituted in beta-D-galactosidase. The effect of methanol on the mutated enzymes was less than on native enzyme. The order of the thermal stability was native enzyme > Asp-537 > Gln-537 > Val-537 enzymes. Overall, the evidence strongly supports the suggestion that Glu-537 is an essential residue of beta-D-galactosidase.

Base Sequence↗

PubMed1994

Characteristics of two-dimensional and color Doppler ultrasonography in Graves' disease.

Color Doppler flow imaging (CDFI) was performed in 24 patients with Graves' disease and the results were compared with those from 8 patients with Hashimoto's disease, 6 patients with simple diffuse goiter, and 15 normal volunteers. All cases were confirmed by clinical, laboratory tests or pathology. CDFI of Graves' disease showed diffuse or localized hypoechoes within the thyroid glands, rich flow signals in the hypoechoes, accelerated flow velocity, and decreased resistance in the superior thyroid arteries (STA) and arteries within the glands. These appearances were characteristic as compared with the controls. The rate of flow in STA of Graves' disease patients was 8 to 10 times higher than that in the normal volunteers. This study demonstrates that CDFI is convenient and efficient as compared with isotope scan and some other laboratory tests, and can be widely used in the diagnosis of Graves' disease.

Adolescent↗

PubMed1993

Primary structure effects on peptide group hydrogen exchange.

The rate of exchange of peptide group NH hydrogens with the hydrogens of aqueous solvent is sensitive to neighboring side chains. To evaluate the effects of protein side chains, all 20 naturally occurring amino acids were studied using dipeptide models. Both inductive and steric blocking effects are apparent. The additivity of nearest-neighbor blocking and inductive effects was tested in oligo- and polypeptides and, surprisingly, confirmed. Reference rates for alanine-containing peptides were determined and effects of temperature considered. These results provide the information necessary to evaluate measured protein NH to ND exchange rates by comparing them with rates to be expected for the same amino acid sequence is unstructured oligo- and polypeptides. The application of this approach to protein studies is discussed.

Alanine↗

PubMed1993

Isotope effects in peptide group hydrogen exchange.

Kinetic and equilibrium isotope effects in peptide group hydrogen exchange reactions were evaluated. Unlike many other reactions, kinetic isotope effects in amide hydrogen exchange are small because exchange pathways are not limited by bond-breaking steps. Rate constants for the acid-catalyzed exchange of peptide group NH, ND, and NT in H2O are essentially identical, but a solvent isotope effect doubles the rate in D2O. Rate constants for base-catalyzed exchange in H2O decrease slowly in the order NH > ND > NT. The alkaline rate constant in D2O is very close to that in H2O when account is taken of the glass electrode pH artifact and the difference in solvent ionization constant. Small equilibrium isotope effects lead to an excess equilibrium accumulation of the heavier isotopes by the peptide group. Results obtained are expressed in terms of rate constants for the random coil polypeptide, poly-DL-alanine, to provide reference rates for protein hydrogen exchange studies as described in Bai et al. [preceding paper in this issued].

Hydrogen↗

PubMed1993

Accumulative effect of two low doses of irradiation in inducing an adaptive response in human lymphocytes.

A chromosomal adaptive response to Co-60 gamma-rays in human lymphocytes was observed over a range of 1-20 cGy pre-exposure doses, with 1 cGy giving optimal reduction in chromatid breaks. A 0.5 cGy dose, which in itself did not induce an adaptive response, did so when given twice within the same cell cycle, and the magnitude of the accumulative effect was strongest when there was an interval of 6 h between the two adaptive doses and between the second adaptive dose and a challenge dose. Reductions equivalent in effect to a single 1 cGy dose were seen when a 0.5 cGy dose was given twice. Delivering two 1 cGy doses had no greater effect than did a single 1 cGy dose.

Adaptation, Physiological↗

PubMed1993

Human myeloperoxidase gene cDNA cloning and expression in acute leukemia.

In this study, the light chain and a part of the heavy chain cDNA segment of human myeloperoxidase (MPO) were cloned with PCR and other DNA recombination techniques from HL-60 cell. The size of the cloned cDNA was 769 bp. A segment about 600bp of the cDNA was analyzed by DNA sequencing and showed no difference from the human MPO cDNA sequences published before. The MPO cDNA was used as a probe to study the MPO gene expression in leukemic cells. The Northern blot analysis and slot blot analysis of RNA isolated from leukemic cell lines and blast cells of acute leukemia showed that MPO gene expression correlated with myeloid lineage and might be used as a marker for the subclassification of acute leukemia.

Acute Disease↗

PubMed1992

Excess levels of cysteine and homocysteine induce tibial dyschondroplasia in broiler chicks.

The effect of excessive levels of cysteine and homocysteine on tibial dyschondroplasia (TD) in broiler chicks was studied. In the first experiment, graded levels of L-cysteine as well as one level of L-homocysteine were supplemented to a corn-soybean-based diet adequate in sulfur amino acids. Levels equal to or above 0.5% supplemental cysteine increased the incidence of TD, and levels equal to or above 0.75% supplemental cysteine increased the severity of TD above that found in chicks fed the basal diet. Also, L-homocysteine at 0.5% induced TD. In the second experiment, graded levels of DL-homocystine were added to the basal diet to determine the threshold value of homocystine needed to induce TD, and a level of ammonium sulfate isosulfurous to 0.45% homocystine was added to a basal diet. The results showed that 0.45% DL-homocystine was the lowest level that increased the severity of TD above that found in chicks fed the basal diet and that sulfate did not induce TD. In the third experiment, a 2 x 2 factorial design was used to investigate the interaction between DL-homocystine and copper. Copper supplementation lessened the severity of TD caused by DL-homocystine. Copper supplementation also tended to improve growth, especially in birds fed DL-homocystine.

Ammonium Sulfate↗

PubMed1992

Wheat middlings as an alternative feedstuff for laying hens.

Three long-term experiments were conducted to evaluate the possibility of using wheat middlings (WM) for laying hens and to study the responses of six strains of commercial laying hens fed WM diet. In Experiment 1,320 layers maintained in floor pens were fed diets containing 45% WM with .25 or .75% salt, or 89% WM with .25% or 1.5% salt. Salt supplementation did not show any beneficial effect on egg production. Hen-day egg production by hens fed the 45% WM diet was significantly higher for hens fed 45% WM than for those fed the 89% WM diet (79 versus 67.5%, 44-wk period). Feed, limestone, and water intakes were increased by the 89% WM diet. Yolk color, Haugh units, hen livability, and reproductive parameters were not different among the dietary treatments. In Experiments 2 and 3, laying hens from six commercial strains (four strains each experiment, 240 hens per strain) were maintained in laying cages in each year, and fed either a corn and soybean meal (CSM) or a 25% WM diet. Results show that neither diet nor strain had effects on hen-day egg production; however, egg weights from Strains A, C, and F were heavier than those from Strains B, D, and E. Feed intakes and feed utilizations were similar among the s trains. The 25% WM diet increased egg weight, feed intake, and feed utilization compared with the CSM diet. Livability of hens was 93.8 to 97.5% and was not affected by either strain or diet. It is concluded that commercial strains of laying hens can be fed diets containing 25 to 45% WM and still have normal hen-day egg production although feed utilization will be poorer.

Analysis of Variance↗

PubMed1992

[Skin tests in patients with history of anaphylactic reaction to penicillin].

Skin tests including immediate patch test (IPT), skin prick test (SPT), or intradermal test (IT) with penicillin G(PenG) and SPT with benzylpenicilloyl human serum albumin (BPO) were done in 54 patients with history of anaphylactic reaction to penicillin or shock of unknown cause. 26 patients with penicillin allergy were diagnosed. BPO specific IgE measured with ELISA gave a lower positive rate in detecting penicillin allergy as compared with the tests mentioned above. The results of skin tests in 26 patients showed that IPT with 500 IU/ml of PenG was not only accurate but also safe. Because no skin injury occurred and PenG residue could be washed out, the amount of PenG penetrated into skin is very small, thus, adverse reactions were very few. It is recommended that IPT with PenG in 500 IU/ml concentration is performed at the beginning of skin tests. If negative, SPT and then IT both with a solution of 500 IU/ml concentration are carried out, until a positive reaction occurs. This procedure is relatively accurate, simple and safe.

Adult↗

PubMed1992

[A study on the activity of three antioxidant enzymes in the brain of experimental acute cerebral ischemia].

The activities of Superoxide Dismutase (SOD), Glutathione Peroxidase (GSH-Px) and Catalase (CAT) in the ischemic cerebral tissue following the unilateral middle cerebral artery occlusion of rats were assessed. In comparison with the sham-operated rats, both SOD and GSH-Px activity in the ischemic area (striatum and fronto-parietal cortex) were significantly reduced by 30 min. of ischemia, GSH-Px activity in the peri-ischemic area (parieto-parasagittal) was significantly reduced as well. It was shown that in the striatum the GSH-Px activity was much higher than that in the cortex. According to our data, it was suggested that in the ischemic condition, cerebral Superoxide (O2-) and Hydrogen Peroxide (H2O2) were accumulated, and thus the polyunsaturated fatty acids in the neuronal membrane were trapped by these free radical. And such a process resulted in neuronal damage. It implicated that the oxygen free radical might be involved in the neuronal damage induced by Dopamine, since the O2- and H2O2 were excessively generated during the oxidative deamination of Dopamine and the free radical scavengers, SOD and GSH-Px were decreased concomitantly in the cerebral ischemic tissue.

Animals↗