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Biomedical subjects

B Cheng

Publications and source records attributed to B Cheng.

At least 55 records · Page 3Linked to original sources
PubMed1999

Effects of prolonged ACTH-stimulation on adrenocortical accumulation of lipofuscin granules in aged rats.

Subcellular deposition of lipofuscin granules is a marker of aging. Human and rodent adrenal cortices accumulate lipofuscin granules with age, but the mechanism that leads to the accumulation is not known. The ultrastructural appearance of lipofuscin granules resembles that of secondary lysosomes. Since adrenocortical subcellular events are predominantly influenced by ACTH action, we therefore studied the effect of prolonged ACTH-stimulation on adrenocortical accumulation of secondary lysosome-like granules, designated herein as lipofuscin granules. Using aged Fischer 344 male rats as a model, we found that a 7 day ACTH stimulation exerts a reducing effect on adrenocortical lipofuscin accumulation. Thus, adrenocortical accumulation of lipofuscin granules with age in vivo may not be an irreversible process.

Adrenal Cortex↗
PubMed1999

An animal and clinical study on the change of neuropeptide Y release evoked by electrical stimulation and myocardial ischemia.

OBJECTIVE: To investigate the change characteristics of neuropeptide Y (NPY) release during acute myocardial ischemia period. METHODS: The animal test was carried out in in situ perfused guinea pig hearts with intact sympathetic innervation. Electrical stimulation-evoked exocytotic release of NPY during ischemia and reperfusion was tested by radioimmunoassay (RIA). The plasma NPY concentrations were measured in patients with acute myocardial infarction (AMI) and angina pectoris (AP) in different times. RESULTS: Electric stimulation of the left ganglion in guinea pig heart evoked an exocytic release of neuropeptide Y. Stimulation after 20 minutes of global ischemia (S2), compared with control period stimulation (S1) produced the inhibition of NPY to a certain extent (S2/S1: 0.72, P < 0.05), whereas the inhibition of NPY release disappeared after 5 minutes reperfusion (with S2/S1 of 1.01, P > 0.05). Ischemia alone, without the electric stimulation, did not apparently induce NPY release. The clinical test found that the plasma NPY level was increased significantly during the acute ischemia attack period of coronary heart disease (CHD). The plasma NPY level reached peak (136.3 +/- 66.5 pg/ml) in patients during the first day after AMI. It began to decrease from the third day and came to normal level in the end of the first week. The plasma NPY level was 159.3 +/- 98.5 pg/ml in AP patients during angina attack. After two weeks treatment, the plasma NPY level was decreased to 118.9 +/- 54.3 pg/ml (P < 0.05). CONCLUSIONS: The NPY release of global ischemia have some relation with sympathetic nerve activity. At the early stage of ischemia, NPY release is inhibited to some degree and the inhibition factors will fade away on reperfusion. NPY interferes with the pathogenesis and the pathophysiolgy.

Aged↗
PubMed1999

[Changes in rat erythrocyte hemorheology caused by morphine dependence].

This study was aimed at the effect of morphine on the biomechanics properties of rat erythrocyte membrane in vivo and in vitro. The shear elastic modulus (E) and the surface viscotsity viscosity (micron) of rat erythrocyte membrane was measured by using the method of the new ektacytometry. The changes in hemorheology caused by morphine dependence were investigated and the mechanisms of the changes are suggested.

Animals↗
PubMed1999

New management of malignant glaucoma by phacoemulsification with posterior chamber foldable intraocular lens implantation.

OBJECTIVE: To investigate the feasibility of phacoemulsification with posterior chamber foldable intraocular lens implantation in the management of malignant glaucoma. PATIENTS AND METHODS: Fourteen patients with malignant glaucoma diagnosed in the Department of Glaucoma were enrolled in the study. 12 patients developed malignant glaucoma after filtration surgery. 1 developed after peripheral iridectomy. 1 patient developed malignant glaucoma without any clear cause. Cataract phacoemulsification was performed. Posterior chamber intraocular foldable lens was implanted in 10 cases of patients. RESULTS: All 14 patients were cured with normal intraocular pressure, normal anterior chamber depth and increased visual acuity. CONCLUSION: Phacoemulsification with posterior chamber foldable intraocular lens implantation is a good alternative in treating malignant glaucoma.

Aged↗
PubMed1999

[Management of infectious endophthalmitis following phacoemulsification].

PURPOSE: To discuss the cause and management of infective endophthalmitis following phacoemulsification. METHODS: Anterior chamber irrigation with anterior chamber drug injection, postoperative systemic and topical antibiotic therapy as well as the use of topical mydriatic agent were applied to 5 of 3,850 eyes which showed endophthalmitis following phacoemulsification. RESULT: All the 5 eyes were saved from infective endophthalmitis. 1 to 5 eyes underwent vitrectomy, 4 of 5 eyes underwent anterior chamber irrigation (wash out). 4 of 5 eyes had satisfactory visual outcome. One of them had poor visual outcome. CONCLUSION: Preoperative contamination of the anterior chamber is the most common source for pathogenic agents responsible for endophthalmitis following phacoemulsification. Prompt anterior chamber irrigation (washout) with anterior chamber drug injection is one of the effective treatment.

Aged↗
PubMed1998

Structure and ligand binding determinants of the recombinant kringle 5 domain of human plasminogen.

The X-ray crystal structure of the recombinant (r) kringle 5 domain of human plasminogen (K5HPg) has been solved by molecular replacement methods using K1HPg as a model and refined at 1.7 A resolution to an R factor of 16.6%. The asymmetric unit of K5HPg is composed of two molecules related by a noncrystallographic 2-fold rotation axis approximately parallel to the z-direction. The lysine binding site (LBS) is defined by the regions His33-Thr37, Pro54-Val58, Pro61-Tyr64, and Leu71-Tyr74 and is occupied in the apo-form by water molecules. A unique feature of the LBS of apo-K5HPg is the substitution by Leu71 for the basic amino acid, arginine, that in other kringle polypeptides forms the donor cationic center for the carboxylate group of omega-amino acid ligands. While wild-type (wt) r-K5HPg interacted weakly with these types of ligands, replacement by site-directed mutagenesis of Leu71 by arginine led to substantially increased affinity of the ligands for the LBS of K5HPg. As a result, binding of omega-amino acids to this mutant kringle (r-K5HPg[L71R]) was restored to levels displayed by the companion much stronger affinity HPg kringles, K1HPg and K4HPg. Correspondingly, alkylamine binding to r-K5HPg[L71R] was considerably attenuated from that shown by wtr-K5HPg. Thus, employing a rational design strategy based on the crystal structure of K5HPg, successful remodeling of the LBS has been accomplished, and has resulted in the conversion of a weak ligand binding kringle to one that possesses an affinity for omega-amino acids that is similar to K1HPg and K4HPg.

Amino Acid Sequence↗
PubMed1998

Effects of prolonged ACTH-stimulation on adrenocortical cholesterol reserve and apolipoprotein E concentration in young and aged Fischer 344 male rats.

Changes in the morphology of rat adrenal cortex with age include increased accumulations of lipid droplets and lipofuscin granules. Because glandular concentrations of cholesteryl esters (CE) and apolipoprotein (apo) E are also increased in parallel, the utilization or metabolism of lipid-droplet stored CE for steroidogenesis might be altered in aging cells. To explore this possibility, adrenocortical cholesterol storage and utilization were studied in 3-6 months-old (mo) (Y) rats and 20-23 mo (O) Fischer 344 male rats. Both groups received either adrenocorticotropin (ACTH1-39, Acthar gel) or gelatin alone daily for seven consecutive days. We found that: (a) the CE concentration in O rats, but not Y animals, was diminished by ACTH. The depleted CE in stimulated-O rats was replenished within five days post stimulation. Failure to deplete CE in stimulated-Y rats was not associated with an insufficient dose of the hormone, since stimulation of Y animals with higher doses of ACTH actually increased the CE concentration. In contrast, adrenocortical free cholesterol concentration remained constant during stimulation regardless of age. (b) The depleted CE in stimulated-O rats was principally comprised of cholesteryl adrenate, cholesteryl arachidonate and cholesteryl cervonate. The accumulated CE in stimulated-Y animals was primarily comprised of cholesteryl adrenate, cholesteryl arachidonate and cholesteryl oleate. (c) Whereas in stimulated-Y rats adrenal apoE concentration declined, the concentration in stimulated O animals was well maintained. (d) In vitro, adrenal homogenate or cytosolic fraction from stimulated-O rats displayed a higher capacity to hydrolyze exogenous CE than its Y counterpart. However, cholesterol esterification with external fatty acid substrates in adrenal homogenate or microsomal fraction was comparable in the two age-groups. Our findings revealed altered adrenocortical cholesterol reserve in O rats to cope with prolonged ACTH-stimulation. Changes in apoE levels and CE hydrolysis activity may be factors associated with this alteration. Depletion and accumulation of adrenocortical CE are reflected in parallel changes in cholesteryl adrenate and cholesteryl arachidonate, suggesting physiologic importance of these polyunsaturated fatty acids during sustained steroidogenesis.

Adrenal Cortex↗
PubMed1998

[Expression of mdr-1 gene in cancer tissue and its association with morphological indexes of esophageal carcinoma].

OBJECTIVE: To detect the levels of mdr-1 gene expression in fresh untreated esophageal carcinomas, and to correlate these levels to current prognostic indicators of morphology. METHODS: mdr-1 gene expression of 46 untreated esophageal carcinoma was investigated with reverse transcription polymerase chain reaction (RT-PCR), and compared with the positive incidences among differentiated grades, TNM stages and macroscopic types of cancer. RESULTS: All 46 samples were pathologically squamous cell carcinoma. The positive incidence of mdr-1 gene expression was 37% (17/46) in the whole group, and 35% (6/17), 40% (8/20), 33% (3/9) for differentiated grade I, II and III respectively. The expression rate of 33% (6/18), 40% (5/12), and 37% (6/16) was for TNM stage IIa, IIb, and III respectively. Macroscopically, the positive incidence was 37% (3/8) in constrictive, 33% (5/15) in fungating, 40% (6/14) in medullary, and 33% (3/9) in ulcerative type. There were no significant differences in each category system of morphology. CONCLUSION: Because of highly expressive level of mdr-1 gene in untreated esophageal carcinoma, we should choose appropriate chemotherapeutic regimen for esophageal Ca. The expression of mdr-1 gene in untreated esophageal cancer was independent of morphologic prognostic indexes without correlation between mdr-1 gene expression and morphological indexes.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1998

Nasopharyngeal carcinoma---time lapse before diagnosis and treatment.

This is a descriptive study of 168 patients with nasopharyngeal carcinoma who were referred to public oncology departments for primary treatment between July and September 1996. The mean duration from the onset of the symptoms to histological diagnosis was 5.0 months; the duration ranged from 6.1 months (for patients presenting with nasal symptoms) to 1.8 months (for those with cranial nerve dysfunction). The mean period between the onset of symptoms and the seeking of medical advice was 2.9months. For 54% of the patients, there was a further delay of up to 2.4 months between the initial medical consultation and referral to the appropriate specialist. The majority (84%) of patients attended public institutions for histological confirmation. The mean total time taken from the onset of symptoms to the commencement of radiotherapy was 6.5 months (range, 1.3-74.0 months)---45% of the delay was attributed to the patient, 20% to initial consultations, 14% to diagnostic arrangement, and 21% to preparation for radiotherapy. Concerted efforts are needed to minimise further the time between the onset of symptoms and treatment. A substantial reduction in this delay can be achieved if both public and primary care doctors were made more aware of the significance of relevant symptoms.

Journal Article↗
PubMed1998

[Genotypic analysis of hepatitis C viruses and its significance in interferon treatment].

To study the genotypes of HCV infection in Shanxi Province and the response of HCV genotypes to interferon therapy, the genotypes of HCV were analysed by restriction fragment length polymorphism in 94 chronic hepatitis C patients who were positive for HCV RNA (RT-PCR). It was shown that 80 patients (85.1%) were group I infection, 12 (12.8%) were group II infection and 2 (2.1%) were group I/II co-infection. 45 chronic hepatitis C patients with different genotypes (35 with HCV group I, 10 with group II) received rIFN alpha-1b 3 MU three times a week for 6 months and were followed up to 12-34 months. The responsive rate was significantly higher in patients with group II infection (80%) than that in patients infected with group I (37.1%) (P < 0.05). Sustained response was observed in 60% for group II and in 17.1% for group I (P < 0.025). The date indicated that HCV group I is the major type of HCV infection in Shanxi Province the and HCV genotype seems to be an important factor in determining the response rate to IFN treatment in patients with chronic hepatitis C.

Adolescent↗
PubMed1997

Time course of the effects of a high-fat diet and voluntary exercise on muscle enzyme activity in Long-Evans rats.

This study examined the time course of the effects of a high-fat diet and voluntary running exercise on rat skeletal muscle carnitine acyltransferase (CAT), beta-hydroxy-acyl-CoA dehydrogenase (HAD), and citrate synthase (CS) activities. Sixty male Long-Evans rats were randomly allocated to receive either a standard (12% fat by energy) laboratory chow diet (CHOW) or a high-fat (76% by energy) diet (HFD) and placed in running wheels for up to 6 weeks. Energy intakes and weekly voluntary running distances were similar in the CHOW and HFD rats. In both groups, weekly training distance more than doubled from week 4 to week 6. However, increased training had little influence on soleus (s) CAT(s), HAD(s), and CS(s) activities. CAT(s) and HAD(s) activities were higher in the HFD rats than in the CHOW rats from 2 weeks onward (p < 0.005), and CS(s) activities were not different between groups and remained constant over time. In contrast, increased training distance after 4 weeks in the CHOW rats resulted in an increase in deep vastus (v) CAT(v) activities to values similar to those in HFD rats prior to increases in training volume (p < 0.005) but had no effect on their HAD(v) and CS(v) activities. Increases in HAD(v) and CS(v) activities with increased training volume were only seen in the HFD rats (p < 0.005). HAD(v) activities and HAD/CS(v) activity ratios correlated with training distance in the HFD rats only (p < 0.001 and p < 0.01, respectively). These results suggest that a high-fat diet improves the beta-oxidation capacity of rat predominantly slow-twitch soleus muscle and enhances the effects of modest levels of training on the mitochondrial density and beta-oxidation capacity of rat deep vastus mixed fast- and slow-twitch muscles.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1997

[Mitomycin C concentrations in rabbit ocular tissues after topical administration during glaucoma filtration surgery].

Using high-performance liquid chromatography, we measured Mitomycin C (MMC) concentrations in conjunctiva, sclera and aqueous of 22 rabbit eyes after single topical administration of 0.2 mg.ml-1 MMC during glaucoma filtration surgery. The peaks of MMC concentrations in conjunctiva, sclera, aqueous were 2.01 micrograms.g-1, 2.95 micrograms.g-1 and 0.16 microgram.ml-1 with half life of 0.63, 0.35 and 0.84 hours respectively. Irrigating the ocular surface with 20 ml of normal saline after MMC application reduced the peak drug concentration to 1/8 in conjunctiva, to 1/5 in sclera and to 1/3 in aqueous. The results showed that the MMC concentrations in conjunctiva and sclera were well above the ID50 of rabbit subconjunctival fibroblast (0.1 microgram.ml-1), and the concentration in aqueous was well below the level known to cause endothelium toxicity (approximately 0.2 mg.ml-1) and retinal toxicity (> 1.3 micrograms.ml-1). Therefore, 0.2 mg.ml-1 MMC can inhibit subconjunctival fibroblast effectively and has no side effect on visual function.

Administration, Topical↗
PubMed1996

mu-Oxo-bis[(5,10,15,20-tetraphenylporphyrinato)oxomolybdenum(V)].

The crystal structure of a new solvated crystal form of the title complex, [¿Mo(O)(TPP)¿2O].1.5H2O.0.5CH2Cl2 (TPP = C44H28N4), has been determined. The dimeric molecule is in a general position, and the overall structural features are extremely similar to those of the previously reported non-solvated form.

Crystallography, X-Ray↗
PubMed1996

Chloro(5,10,15,20-tetraphenylporphyrinato)manganese(III) with 4/m symmetry.

The crystal structure of [Mn(TPP)Cl] in space group I4/m (where TPP is C44H28N4) has been determined. The unit cell contains two full molecules, with one eighth of a molecule unique. An out-of-plane model for the Mn atom was applied and all non-H atoms were refined anisotropically. The Mn--N distance is 2.002 (3) A, the axial Mn--Cl distance is 2.297 (15) A and the out-of-plane displacement of the Mn atom is 0.16 A. The possibility of a reverse-doming porphyrin core conformation is mentioned briefly.

Crystallography, X-Ray↗