Biomedical subjects

H Liang

Publications and source records attributed to H Liang.

At least 127 records · Page 7Linked to original sources

PubMed1998

Laser scissors and tweezers.

In summary, we described the use of laser scissors and tweezers from three perspectives: (a) the historical background from which these two techniques evolved, (b) an understanding and lack of understanding of the mechanisms of interaction with the biological systems, and (c) the applications of the scissors and tweezers alone and in combination. As the technology improves and we gain a better understanding of how these two tools operate they will become even more useful in probing cell structure and function, as well as practically manipulating cells in genetics, oncology, and developmental biology.

Animals↗

PubMed1998

5q- in a child with refractory anemia with excess blasts: similarities to 5q- syndrome in adults.

A 19-month-old boy was referred to our institution because of chronic macrocytic anemia and severe thrombocytopenia. At age 17 months, he had developed petechiae. He had a leukocyte count of 4.4 x 10(9)/L, hemoglobin concentration of 7.9 g/dL, packed cell volume of 21%, mean corpuscular volume of 101 fL, and platelet count of 19 x 10(9)/L. At the time of referral, a bone marrow aspirate and biopsy revealed myelodysplastic changes that included megakaryocytic hyperplasia with hypolobated megakaryocytes, megaloblastoid erythropoiesis, 12% blast cells, and bone marrow fibrosis; the diagnosis was refractory anemia with excess blasts (RAEB). Cytogenetic analysis showed the following abnormalities: 47, XY, inv(3)(p21q25), del(5)(q22q31), +21/46, XY. By dinucleotide polymorphism analysis, the 5q22-q31 loci were normal in peripheral blood granulocytes. Because of severe thrombocytopenia that became refractory to platelet transfusions and because of possible progression to leukemia, the patient received an unrelated-donor bone marrow transplant. Recovery was complicated by a visceral fungal infection, but the patient now has normal, fully reconstituted bone marrow function. This patient is the youngest to be reported with RAEB and a 5q- anomaly accompanied by thrombocytopenia, megakaryocytic hyperplasia with hypolobated megakaryocytes, and macrocytic anemia with megaloblastoid erythropoiesis, similar to "5q- syndrome" in adults.

Anemia, Refractory↗

PubMed1998

Specific bone-protective effects of metabolites/derivatives of tamoxifen and clomiphene in ovariectomized rats.

In the ovariectomized (ovx) rat, the nonsteroidal antiestrogens, clomiphene (CLO) and tamoxifen (TAM), at dose levels that prevent development of osteopenia to a degree approaching that of 17beta-estradiol are, in contrast to 17beta-estradiol, only weakly uterotrophic. Metabolites of CLO and TAM might contribute differentially to these effects. Thus, we have evaluated bone protective and uterine effects in ovx rats of two such metabolites: 4-hydroxy CLO, produced by p-hydroxylation of CLO; and 4HTA, produced from TAM by stepwise replacement of its dimethylaminoethyl side chain with an acetic acid moiety, accompanied by p-hydroxylation. Also reported are effects of D4HTA, the dihydrodesethyl derivative of 4HTA previously characterized as a full estrogen mimetic in vitro. Administration of 4-hydroxy CLO (2.5 mg/kg subcutaneously) 5 days/week for 5 weeks to 3-month-old ovx rats resulted in complete prevention of bone loss and suppression of bone turnover to levels comparable to those of intact controls and to those of ovx animals similarly receiving 17beta-estradiol (10 microg/kg). However, uterine weight in animals receiving 4-hydroxy CLO was 64% less than that in 17beta-estradiol-treated animals. Although 4HTA (3.7 mg/kg s.c.) had a modest uterotrophic effect, it did not prevent bone loss associated with ovariectomy. In contrast, D4HTA (3.6 mg/kg s.c.) partially reduced bone turnover indicators and cancellous bone loss in a manner similar in many ways to that observed in TAM-treated ovx animals, but it had no uterotrophic effect. These results suggest that, although 4HTA does not contribute to the bone-protective effect of TAM, 4-hydroxy CLO might augment that of CLO.

Animals↗

PubMed1998

Impaired release of tissue plasminogen activator from the endothelium in Graves' disease - indicator of endothelial dysfunction and reduced fibrinolytic capacity.

BACKGROUND: Patients with hyperthyroidism have increased plasma levels of von Willebrand factor (vWF). Changes in tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1), another two endothelium-derived proteins and modulators of blood fibrinolytic activity, have not been reported in hyperthyroidism. METHODS: The release of t-PA by vascular endothelial cells after venous occlusion, basal blood concentrations of t-PA, PAI-1 and vWF were studied in 33 patients with hyperthyroidism, with most of them followed up 30 days after iodine radiotherapy. RESULTS: Compared with control subjects, both the basal t-PA levels in plasma and the increase in t-PA levels with venous occlusion were significantly decreased in patients (P < 0.001), whereas plasma PAI-1 and vWF levels were increased greatly (P < 0.001). At follow-up, patients with normal plasma free thyroxine (T4) and total tri-iodothyronine (T3) showed similar plasma levels of t-PA, PAI-1, vWF and release of t-PA from endothelial cells as the control subjects (P > 0.05). In those with persistent elevated T4 or T3 levels, however, the basal plasma t-PA level and the released t-PA from endothelial cells during venous occlusion were significantly lower than in the control subjects (P < 0.001 and P < 0.005), and blood concentrations of PAI-1 and vWF did not return to the normal range (P < 0.001 and P < 0.001). In all patients, serum thyroid hormone concentrations were inversely correlated with basal plasma t-PA (T4: r = -0.549, P < 0. 001; T3: r = -0.463, P < 0.001) and released t-PA by endothelial cells (T4: r = -0.505, P < 0.001; T3: r = -0.450, P < 0.001) but strongly correlated with plasma PAI-1 (T4: r = 0.613, P < 0.001; T3: r = 0.577, P < 0.001) and vWF (T4: r = 0.457, P < 0.001; T3: r = 0. 564, P < 0.001). CONCLUSION: Hyperthyroid patients may experience vascular endothelial dysfunction and reduced fibrinolytic activity in blood.

Adult↗

PubMed1998

Small intestinal submucosa: a rapidly resorbed bioscaffold for augmentation cystoplasty in a dog model.

The extracellular matrix (ECM) of porcine small intestinal submucosa (SIS) has been shown to serve as a resorbable scaffold for tissue repair and remodeling in several body locations including the urinary bladder. The rate of resorption and extent of SIS degradation are unknown. Nine dogs were divided into three equal groups. Approximately 40% of the anterior dome of the urinary bladder was resected in each dog and replaced with porcine SIS. One group of dogs was sacrificed at each of 4, 8, and 12 weeks after surgery and the fate of the implanted SIS determined by immunohistochemical methods using a monoclonal antibody specific for porcine-derived SIS. By 4 weeks after surgery, only scattered remnants of SIS were present in the remodeled urinary bladder and these positively staining foci were surrounded by an extensive new host derived ECM and neovascularization. There was a continuous layer of transitional epithelium on the luminal surface by 4 weeks. No evidence for the originally implanted SIS could be found at either 8 or 12 weeks and bundles of organized smooth muscle cells were present at the operative site. In summary, SIS is rapidly and extensively degraded when used as a bioscaffold for augmentation cystoplasty in the dog model.

Animals↗

PubMed1998

Trinucleotide insertions, deletions, and point mutations in glucose transporters confer K+ uptake in Saccharomyces cerevisiae.

Deletion of TRK1 and TRK2 abolishes high-affinity K+ uptake in Saccharomyces cerevisiae, resulting in the inability to grow on typical synthetic growth medium unless it is supplemented with very high concentrations of potassium. Selection for spontaneous suppressors that restored growth of trk1delta trk2delta cells on K+-limiting medium led to the isolation of cells with unusual gain-of-function mutations in the glucose transporter genes HXT1 and HXT3 and the glucose/galactose transporter gene GAL2. 86Rb uptake assays demonstrated that the suppressor mutations conferred increased uptake of the ion. In addition to K+, the mutant hexose transporters also conferred permeation of other cations, including Na+. Because the selection strategy required such gain of function, mutations that disrupted transporter maturation or localization to the plasma membrane were avoided. Thus, the importance of specific sites in glucose transport could be independently assessed by testing for the ability of the mutant transporter to restore glucose-dependent growth to cells containing null alleles of all of the known functional glucose transporter genes. Twelve sites, most of which are conserved among eukaryotic hexose transporters, were revealed to be essential for glucose transport. Four of these have previously been shown to be essential for glucose transport by animal or plant transporters. Eight represented sites not previously known to be crucial for glucose uptake. Each suppressor mutant harbored a single mutation that altered an amino acid(s) within or immediately adjacent to a putative transmembrane domain of the transporter. Seven of 38 independent suppressor mutations consisted of in-frame insertions or deletions. The nature of the insertions and deletions revealed a striking DNA template dependency: each insertion generated a trinucleotide repeat, and each deletion involved the removal of a repeated nucleotide sequence.

Alleles↗

PubMed1998

[The carcinogenetic and tumor-promoting effects of concentrated Helicobacter pylori culture supernatant in rats].

OBJECTIVE: To investigate the carcinogenetic and tumor-promoting effect of concentrated Helicobacter pylori culture supernatant (CHCS). METHODS: 0.25% and 0.5% CHCS in drinking water administered orally for 52 weeks in rats, the changes of mucosal thickness, adherent mucosal mucus amount, DNA synthesis rate and precancerous lesions incidence in different times were examined, and the promoting effect of CHCS used in different periods on experimental carcinogenesis induced by MNNG was also clarified. RESULTS: Decreased mucosal thickness and amount of mucosal adherent mucus, increased DNA synthesis were found after CHCS feeding for 5 weeks in a dose- and time-dependent manner. By the end of the experiment at the 52nd week, the incidence of intestinal metaplasia(IM), sulfomucin positive IM and dysplasia in 0.5% CHCS group(57%, 39%, 18% respectively) were significantly higher than those in 0.25% CHCS group(28%, 10%, 3% respectively) and control group(7%, 0%, 0% respectively). Whenever CHCS was used prior to, together with, or following MNNG administration, the incidences of gastric cancer and precancerous lesions were significantly increased in comparison with those in the rats treated with MNNG alone. CONCLUSION: Hp cytotoxin(s) may have direct carcinogenetic and tumor-promoting effects.

Animals↗

PubMed1998

[Embolotherapy of craniofacial tumors and vascular diseases: assessing the effect of different embolic agents].

To assess the effect of different embolic agents in curing craniofacial tumors and vascular diseases, 21 patients who were treated by intra-arterial embolization were divided into three groups: gelfoams, bletilla striatas and coils. The results showed that 8 cases of preoperative patients in gelfoams group had a good effect and bleeding were reduced during operation. One patient had vascular recanalization at 1 month after embolization with gelfoam. All patients in bletilla striatas had ideal effect. In coils group, collateral supplying arteries were found in 3 patients at once after embolization and the others had a good effect. In conclusion, craniofacial tumors and vascular diseases were fit to embolotherapy. The selection of embolic agents should be gelfoam in preoperative embolization and bletilla striata in palliative treatment There were not severe complications.

Adolescent↗

PubMed1998

Bletilla striata as a vascular embolizing agent in interventional treatment of primary hepatic carcinoma.

OBJECTIVE: To evaluate Bletilla striata as a vascular embolizing agent in interventional treatment of primary hepatic carcinoma. METHODS: We made a vascular embolizing agent from a Chinese medicinal herb, Bletilla striata (bai ji). From October 1991 to January 1995, 56 patients with primary hepatic carcinoma were treated by hepatic arterial chemoembolization with Bletilla striata angioembolus, and 50 patients with primary hepatic carcinoma who were treated by conventional gelfoam embolization served as controls. All patients were followed up for 10-48 months. RESULTS: Embolization with the Bletilla striata powder produced extensive and permanent vascular obstruction, resulting in marked shrinkage of the tumor and significant decrease of serum alpha fetoprotein (AFP) level. After embolization, less collateral circulation formed later. The treatment interval was prolonged to an average of 7 months. The 1-, 2- and 3-year survival rates were 81.9%, 44.9%, and 33.6%, respectively, with a mean survival period of 19.8 months. All the clinical parameters were better than those in the control group treated by conventional gelfoam embolization. CONCLUSION: Bletilla striata angioembolus is a good vascular embolizing agent for treating PHC.

Adult↗

PubMed1998

[Clinical study on active factors of vascular endothelial cells in acute cerebral infarction patients and therapeutical effect of activating blood stasis].

OBJECTIVE: To investigate the level of plasma tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI), 6-keto-prostaglandin F1 alpha(PGF1 alpha), thromboxane B2(TXB2), factor VIII related antigen (VIII R:Ag) in acute cerebral infarction (ACI) patients with different TCM syndrome-type and the therapeutical effect of activating blood stasis (ABS). METHODS: Plasma fibrolysin system, prostaglandin system, and VIII R:Ag of 20 healthy subjects and 66 ACI patients were determined. The 45 of 66 cases were treated with ABS randomly and prospectively, 20 cases were treated by difibrase batroboxobin (DF-521), only 25 cases were treated by DF-521 together with Heart-Brain Mixture (HBM), on activating blood stasis mixture, concurrently. RESULTS: (1) The activity of tPA, ratio of tPA/(tPA + PAI) and level of PGF1 alpha decreased significantly, the level of VIII R:Ag increased remarkably in ACI patients than those of the controlled subjects. (2) Between Differentiation of Deficiency and Excess Syndromes, the level of above index changed more remarkably in the case with Excess Syndrome. Insignificant change of index shown in Deficiency cases except activity of tPA. (3) No more improvement of nerve impairment was shown between group of DF-521 together with HBM and DF-521 alone within 30 days. However, the improvement of index such as level of VIII R:Ag, ratio of tPA/(tPA + PAI) and TXB2/PGF1 alpha showed significant change between the beginning and end of treatment of DF-521 with HBM group. CONCLUSIONS: The vascular endothelial impairment was more serious in ACI patients with Excess than those with Deficiency Syndrome. DF-521 combining with HBM could protect vascular endothelial cells and improve the fibrolytic system and prostaglandin system.

6-Ketoprostaglandin F1 alpha↗

PubMed1998

[Analysis and toxicological evaluation of hazardous gases in sealed cabin].

82 volatile organic compounds (VOCs) of eight organic sorts and 3 target inorganic compounds in a sealed cabin that simulating the flying spaceship were identified and quantified for 5 d, the law of hazardous gas concentration variation was discussed, and the atmosphere toxicology was evaluated preliminarily. It provides a basis for detecting gas compounds and evaluating the atmosphere toxicology in the spaceship.

Air Pollutants↗

PubMed1998

[A new saikosaponin from Bupleurum Chinese DC].

Bupleurum chinese DC. is a well-known and very important traditional Chinese drug. It is often used to treat common cold with fever, alternating chill and fever, the feeling of fullness and oppression in the chest. A new saikosaponin was isolated from Bupleurum chinese DC. and its structure was identified as 3 beta, 16 beta, 28-trihydroxy-11-alpha-methoxy-olean-12-ene-3-O-beta-D-glucosyl-(1-->3)-beta D-fucoside on the basis of chemical and spectral evidence. In addition, six known saikosaponins were isolated and characterized as saikosaponin a, saikosaponin d, saikosaponin c, saikosaponin f, saikosaponin b3 and saikosaponin b2. All these compounds were isolated from Bupleurum chinese DC. for the first time.

Bupleurum↗

PubMed1998

[A new saikosaponin from Bupleurum chinense DC].

Bupleurum chinense DC. is a well-known and very important traditional Chinese drug. It is often used to treat common cold with fever, alternating chill and fever, feeling of fullness and oppression in the chest. A new saikosaponin was isolated from Bupleurum chinense DC. and its structure was identified as 3-O-[beta-D-glucopyranosyl (1-->3)-beta-D-fucopyranosyl]-3 beta, 16 alpha, 23, 28-tetrahydroxy-olean-11, 13 (18)-dien-30-oic acid 30-O-[xylityl(1-->1)]-beta-D-glucopyranosyl-6-ester on the basis of chemical and spectral evidence. In addition, three known saikosaponins were isolated and characterized as saikosaponin 1, 2"-O-acetyl-saikosaponin b2 and 2"-O-acetyl-saikosaponin a. All the compounds were isolated from Bupleurum chinense DC. for the first time.

Bupleurum↗

PubMed1998

[Function of modified YSI membrane in glucose sensor].

This study was designed to improve the stability, accuracy and interference resistance of the glucose sensor system and to fomodify the correlation between electrode current and glucose concentration. Catalase was immobilized in YSI membrane. Experiments in vitro were conducted in different concentrations of glucose or ascorbic acid or paracetomol. The results showed the background current, 0.37 +/- 0.06 nA; the drift values in 0 mM G.S. and 10 mM G.S. were (0.20 +/- 0.14)%/30 hr and (3.22 +/- 0.40)%/30 hr respectively. The mean value of drift in 10 mM G.S. was 0.103% mM-1hr-1. The correlation between electrode current and glucose concentration gave satisfaction (r = 0.986); it ranged from 0 mM G.S. to 20 mM G.S. Lower concentration of ascorbic cid could not interfere n the glucose sensor system; higher concentration of ascorbic acid and paracetomol only produced very low interference current. These suggest that the modified YSI membrane contributes greatly to a stable, accurate and reliable glucose sensor system.

Biosensing Techniques↗

PubMed1998

[Pulsatile microdialysis method with glucose sensor system].

To develop a miniature subcutaneous glucose sensor system, to simplify calibration procedure before or after glucose monitor, and to improve its temperature characteristics, a pulsatile micropump and the microdialysis technique were used. The experiments of glucose recovery in 5.5 mM and 10 mM G.S. and the temperature experiment from 20 degrees C to 40 degrees C were conducted. The results showed that glucose recovery was (97 +/- 2)%, the current values of glucose sensor varied with temperature, but the temperature parameter was only 3.4%. These indicate that the glucose sensor system is miniature and the calibration procedure is simple. Because of its modified temperature characterisic, it is useful to monitor the blood glucose of feverish diabetics.

Biosensing Techniques↗

PubMed1998

O-Mannosylation of Pichia pastoris cellular and recombinant proteins.

O-linked saccharides were released from a major cell wall glycoprotein and from cellular mannan-protein complexes obtained from Pichia pastoris cells. Analysis by a variety of chromatographic methods and exoglycosidase digestions revealed the presence of mannose and (alpha1-2)-linked dimer, trimer and tetramer saccharides of mannose. The recombinant kringle 1-4 domain of human plasminogen expressed in P. pastoris was subjected to hydrazinolysis of both O- and N-linked saccharides. Only a very small quantity of N-linked oligosaccharides was present on the Asn289 consensus site. The major products were O-linked (alpha1-2)-linked mannans, containing dimeric, trimeric, tetrameric and pentameric oligosaccharides with the major amount of the total saccharides being distributed approximately equally between the dimer and trimer components. These results show that short O-linked saccharides of mannose containing (alpha1-2) glycosidic linkages are present in P. pastoris cells and expressed proteins.

Carbohydrate Conformation↗

PubMed1997

Three-dimensional structures of proteins involved in programmed cell death.

Programmed cell death (apoptosis) is a controlled process by which unwanted cells are selectively eliminated. Several families of proteins including the Bcl-2, tumor necrosis factor receptor 1, and caspase families play essential roles in the regulation, signaling, and execution of the genetic cell death program. The recently described three-dimensional structures of members of these families elucidate the structural basis of their functions and provide insights into the mechanisms by which these proteins regulate apoptosis.

Animals↗

PubMed1997

Localization of SMAD5 and its evaluation as a candidate myeloid tumor suppressor.

Acquired interstitial or complete losses of chromosome 5 are recurring anomalies associated with preleukemic myelodysplasia and acute myelogenous leukemia with a poor prognosis. Previous studies have delineated a potential myeloid tumor suppressor locus to a <2.4-Mb interval between the genes for IL9 and EGR1 on 5q31. In this report, we have localized the SMAD5 gene, a homologue of the tumor suppressor genes SMAD4/DPC-4 and SMAD2/JV18.1, to the minimal myeloid tumor suppressor locus and characterized its open reading frame and genomic organization. SMAD5 transcripts are readily detectable in hematolymphoid tissues and leukemic blasts. Absence of intragenic mutations in the remaining SMAD5 allele of leukemic patients and multiple solid tumor cell lines prescreened for loss of heterozygosity suggests that SMAD5 may not be a common target of somatic inactivation in malignancy.

Base Sequence↗