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Biomedical subjects

B Cheng

Publications and source records attributed to B Cheng.

At least 37 records · Page 2Linked to original sources
PubMed2001

[The cause and management of acute high intraocular pressure in phacoemulsification].

OBJECTIVE: To investigate the cause and management of acute high intraocular pressure and shallow anterior chamber in phacoemulsification. METHODS: A retrospective study was done on 1,500 eyes performed phacoemulsification. Eleven of 1,500 eyes showed higher intraocular pressure and shallowing of the anterior chamber during phacoemulsification. But phacoemulsification was successfully achieved after giving hyperosmotic agents, increasing infusion pressure and reducing aspiration rate as well as flow rate. RESULTS: Of 11 eyes, 10 eyes were treated by management of non vitrectomy. One of 11 eyes was unresponsive to medical management and require the use of pars plana vitrectomy. Phaco was performed in all patients. In 4 of 11 eyes, visual acuity postoperatively were 0.7 or better. Five of 11 eyes were 0.3 to 0.5. One eye was 0.05 and one was HM/30 cm. CONCLUSION: Aqueous misdirection, retrobulbar hemorrhage and intraoperative suprachoroidal hemorrhage are common causes of acute high intracular pressure in phaco. Most of patients could be performed phaco after medical treatment. If patients failed to improve after medical treatment, par plana vitrectomy is a useful method.

Aged↗
PubMed2000

The inhibition of Escherichia coli lac operon gene expression by antigene oligonucleotides-mathematical modeling.

Gene transcription is regulated by transcription factors that can bind to specific regions on DNA. Antigene oligonucleotides (oligos) can bind to specific regions on DNA and form a triplex with the double-stranded DNA. The triplex can competitively inhibit the binding of transcription factors and, as a result, transcription can be inhibited. A genetically structured model has been developed to quantitatively describe the inhibition of the Escherichia coli lac operon gene expression by triplex-forming oligos. The model predicts that the effect of triplex-forming oligos on the lac operon gene expression depends on their target sites. Oligonucleotides targeted to the operator are much more effective than those targeted to other regulatory sites on the lac operon. In some cases, the effect of oligo binding is similar to that of a mutation in the lac operon. The model provides insight as to the specific binding site to be targeted to achieve the most effective inhibition of gene expression. The model is also capable of predicting the oligo concentration needed to inhibit gene expression, which is in general agreement with results reported by other investigators.

Computer Simulation↗
PubMed2000

Molybdenum(V) on an oxide string. Formation and solution stability of the linear complex (mu-trans-dioxo(tetraphenylporphyrinato)molybdenato(V))- bis(oxo(tetraphenylporphyrinato)molybdenum(V)) perchlorate.

The unusual linear trinuclear complex [Mo3O4(TPP)3]+ is formed in solution upon the reaction of [MoO(TPP)-(OClO3)] with [[MoO(TPP)]2O], and an equilibrium between [Mo3O4(TPP)3]+ and its constituent species is rapidly established. Spectrophotometric experiments suggest that [Mo3O4(TPP)3]+ is the predominant species found in solutions resulting from the mixture of [MoO(TPP)(OClO3)] and [[MoO(TPP)]2O], and its formation is strongly favored (log K = 5.5 +/- 0.5 M-1). No evidence of higher oligomers has been observed. A mechanism for the formation of [Mo3O4(TPP)3]+ by the controlled hydrolysis of [MoO(TPP)(OClO3)] is proposed.

Catalysis↗
PubMed2000

Evidence for control of adenosine metabolism in rat oxidative skeletal muscle by changes in pH.

1. We investigated the effects of pH elevation or depression on adenosine output from buffer-perfused rat gracilis muscle, and kinetic properties of adenosine-forming enzymes, 5'-nucleotidase (5'N) and non-specific phosphatase (PT), and adenosine-removing enzymes, adenosine kinase (AK) and adenosine deaminase (AD), in homogenates of muscle. 2. Depression of the perfusion buffer pH from 7.4 to 6.8, by addition of sodium acetate, reduced arterial perfusion pressure from 8.44 +/- 1.44 to 7.33 +/- 0.58 kPa, and increased adenosine output from 35 +/- 5 to 56 +/- 6 pmol min-1 (g wet wt muscle)-1 and AMP output from 1.8 +/- 0.3 to 9.1 +/- 3.9 pmol min-1 (g wet wt muscle)-1. 3. Elevation of the buffer pH to 7.8, by addition of ammonium chloride, reduced arterial perfusion pressure from 8.74 +/- 0.57 to 6.96 +/- 1.37 kPa, and increased adenosine output from 25 +/- 5 to 47 +/- 8 pmol min-1 (g wet wt muscle)-1 and AMP output from 3.7 +/- 1.1 to 24.6 +/- 6.8 pmol min-1 (g wet wt muscle)-1. 4. Activity of membrane-bound 5'N was an order of magnitude higher than that of either cytosolic 5'N or PT: pH depression reduced the K(m) of 5'N, which increased its capacity to form adenosine by 10-20% for every 0.5 unit decrease inpH within the physiological range. PT was only found in the membrane fraction: its contribution to extracellular adenosine formation increased from about 5% at pH 7.0 to about 15% at pH 8.0. 5. Cytosolic 5'N had a low activity, which was unaffected by pH; the rate of intracellular adenosine formation was an order of magnitude lower than the rate of adenosine removal by adenosine kinase or adenosine deaminase, which were both exclusively intracellular enzymes. 6. We conclude that (i) adenosine is formed in the extracellular compartment of rat skeletal muscle, principally by membrane-bound 5'N, where it is protected from enzymatic breakdown; (ii) adenosine is formed intracellularly at a very low rate, and is unlikely to leave the cell; (iii) enhanced adenosine formation at low pH is driven by an increased extracellular AMP concentration and an increased affinity of membrane-bound 5'N for AMP; (iv) enhanced adenosine formation at high pH is driven solely by the elevated extracellular AMP concentration, since the catalytic capacity of membrane 5'N is reduced at high pH.

5'-Nucleotidase↗
PubMed2000

Colon interposition.

In the anatomy of the colon vasculature, the ascending branch of the left colic artery is the primary supplying vessel (96.91%). Isoperistaltic transposition of the transverse colon is preferred (83.58%). Riolan's vascular arcade is not a major vessel of the colon. It can only be found in less than 10% of patients, and whether or not this arcade is complete cannot be used as criterion to judge colon blood supply. Animal experiments and clinical studies have confirmed the superiority of one-layer over two-layer anastomosis. The former is simpler, safer, and more reliable, with a lower incidence of anastomotic leak or stricture. Based on a comprehensive evaluation of the disease type, patient age, heart and lung functions, nutritional status, and accompanying diseases, three colon transposition routes are available (anterosternal subcutaneous tunnel, retrosternal tunnel, and esophageal bed passage). The advantages and disadvantages of each route are analyzed, and the left-middle-left retrosternal route is described. The indications for esophageal reconstruction with colon operation (ERC) were collected and verified, increasing the number of indications to seven categories of diseases. The main complications of ERC, i.e., colon segment necrosis, anastomotic leak, recurrent laryngeal nerve injury, and intestinal obstruction were systematically studied, and their causes and prevention are detailed. The number of patients is the highest in a single unit among all the published reports. The incidence of complications and deaths are the lowest.

Adolescent↗
PubMed2000

Similarities of multiple fracturing on a neutron star and on the Earth.

In this paper the similarities of multiple fracturing on a neutron star and on the Earth are explored, including power-law energy distributions, clustering, and the symptoms of transition to a major rupture. These similarities may reflect a scenario of a critical transition, common for a broader class of nonlinear systems.

Astronomy↗
PubMed2000

Number and sites of rDNA loci of Guizotia abyssinica (L. f.) Cass. as determined by fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) was employed on somatic chromosome preparations of Guizotia abyssinica using a DNA probe of the 18S-5.8S-26S rRNA genes including the transcribed and non-transcribed spacer sequences. A maximum of six major and two minor signal sites of rDNA was observed. However, the minor signals were not persistently detected. The positions of the FISH signals coincided with the sites of the nucleolar organizer regions and their adjacent C-banded heterochromatin when present.

Asteraceae↗
PubMed2000

High-pathogenicity island of Yersinia spp. in Escherichia coli strains isolated from diarrhea patients in China.

The high-pathogenicity island (HPI) of Yersinia has been observed in 93% of 60 enteroadhesive Escherichia coli strains and 80% of E. coli strains isolated from blood samples. In the present study we investigated 671 fecal samples from patients with diarrhea in Shandong Province, China, and isolated HPI-harboring E. coli from 6. 26% of the samples. The isolation rates for patients with diarrhea in three age groups, 10 to 20, 30 to 40, and 50 to 60 years, were 6. 70, 12.35, and 10.81%, respectively. Therefore, HPI-harboring E. coli is the third most frequently isolated enteric pathogen from patients with diarrhea. Vomiting and abdominal pain were recorded for 33.33 and 66.67% of the patients, respectively. Stools with blood were observed for 9.52% of the patients. Twenty-four of 42 (57%) patients experienced a temperature over 37.4 degrees C. These observations indicate that HPI-harboring E. coli is one of the major causes of diarrheal disease in China and that the clinical symptoms caused by HPI-harboring E. coli differ from those caused by enteroadhesive E. coli.

Adolescent↗
PubMed2000

Effects of morphine on rheological properties of rat red blood cells.

To evaluate the effect of morphine on red blood cells, in vivo and in vitro rat models of morphine dependence were established. Rheological properties of rat red cells were measured by ektacytometry; the biophysical changes in the membrane of rat red cells were measured by the Fourier-Transformed Infrared technique (FT-IR) and the fluorescence depolarization method. The results show that the membrane fluidity of red cells was greatly reduced by morphine and the secondary structure of membrane proteins was changed. This suggests that morphine affects the rat red cell membrane directly, rather than through opioids-receptors.

Animals↗
PubMed2000

[Mature time demarcation of human immature myocardium].

OBJECTIVE: To study the mature time demarcation of human immature myocardium. METHODS: The morpho-ultrastructure, calcium metabolism, energy metabolism and oxygen free radicals metabolism of myocardium of children with ventricular septal defect without pulmonary hypertension or any clinical symptoms were studied at different ages. RESULTS: The immature myocardium possessed its own structure and functional characteristics. Before viripotent period, the age-related myocardial changes developed progressively to mature and almost approached to mature levels at 6-9 years old. The indices of immature myocardium developing to mature levels were inconsistent. CONCLUSION: The structure and function of human immature myocardium approaches to mature levels at 6-9 years old.

Adolescent↗
PubMed2000

[Maintenance of foot sensory function by end-to-side neurorrhaphy].

OBJECTIVE: The purpose of this paper is to introduce the experience in maintaining or reconstructing foot sensory function after harvesting skin flap from the leg. METHODS: After dissecting the fasciacutaneous flap in the medial leg, the end-to-side neurorrhaphy was performed between the distal saphenous nerve and the sural nerve. When the retrograde-flow neurocutaneous island flap was raised, the end-to-side neurorrhaphy was carried out between the sural nerve carried by the flap and the cutaneous nerve of the foot dorsum. Also a less important cutaneous nerve branch can be harvested and implanted into the denervated flap in the foot with the other end of the nerve sutured to the lateral side of the cutaneous nerve of the foot dorsum. RESULTS: This operation was performed on three patients. Postoperative follow-up of 9 to 36 months revealed good results. CONCLUSION: This technique is simple and effective.

Adult↗
PubMed2000

[Phacoemulsification with silicone foldable intraocular lens implantation through a small incision in glaucomatous eyes after filtering surgery].

OBJECTIVE: To investigate the method of cataract extraction in eyes that had undergone glaucoma filtering surgery and its effects on filtering bleb. METHODS: Phacoemulsification with posterior chamber intraocular lens implantation was performed on 262 eyes with a preexisting filtration bleb, in which at the temporal clear cornea a lateral or inferior lateral limbal incision was selected, the pupil sphincter was cut and the iris was sewed for the small and fixed pupil. RESULTS: The postoperative visual acuity of all patients improved in different degrees, with >or= 0.5 in 74.0% in the first month. The postoperative IOP increased by 3.08 mmHg. The functional filtering bleb was not apparently cicatrized. CONCLUSIONS: Glaucomatous eyes with cataract after filtering operation can rehabilitate their visual acuity and maintain the functional filtering bleb by phacoemulsification with foldable intraocular lens implantation through a temporal clear corneal incision or lateral scleral pocket incision. Theoretically, the effect of a transparent corneal incision on filtering bleb is less than that of a scleral pocket incision.

Aged↗
PubMed2000

[Detection of Escherichia coli strains harboring pathogenicity island of Yersinia enterolitica in diarrheal patients and animals in China].

OBJECTIVE: To investigate the prevalence of Escherichia coil strains harboring high pathogenicity island of Yersinia enterocolitica in diarrhea patients, animals, food samples and resulted clinical symptoms. METHODS: Colony hybridization, DNA dot hybridization and polymerase chain reaction (PCR) were used. RESULTS: HPI - harboring E. coli were found in the strains isolated in various provinces of China. The isolation rates were 27.05% (436/1,612) in the strains isolated from diarrhea patients, 10.23% (9/88) in the strains isolated from food samples and 5.71% (16/280) in the strains isolated from feces of cattle and pigs. Typical clinical symptoms of diarrhea caused by HPI - harboring E, coli were inappetency, abdominal pain, shiver and vapidity. Patient's temperature was usually normal or low. Over six episodes of diarrhea was frequently observed, of which most were unformed stools with mucous. CONCLUSION: E. coli strains harboring high - pathogenicity - island of Yersinia species were frequently isolated from diarrhea patients, animals and food samples as well, which might be one of the major causes of diarrhea in China.

Animals↗
PubMed2000

[Phacoemulsification in eyes with Fuchs' heterochromic iridocyclitis].

PURPOSE: To evaluate the effect and safety of phacoemulsification with intraocular lens (IOL) implantation in eyes with Fuchs' heterochromic iridocyclitis. METHODS: We reviewed the 13 patients (14 eyes) with heterochromic iridocyclitis who had phacoemulsification and IOL implantation. Intraoperative and postoperative complication was observed. RESULTS: Intraoperative complication included miosis and hemorrhage in anterior chamber. Postoperative complication were glaucoma and hyphemia. Best corrected postoperative visual acuity was 1.0 or better in 65% of eyes. CONCLUSION: Eyes with heterochromic iridocyclitis tolerated well to the phacoemulsification with IOL implantation.

Adult↗
PubMed1999

Preparation of Shell-Core Cu(2)O-Cu Nanocomposite Particles and Cu Nanoparticles in a New Microemulsion System.

Shell-core Cu(2)O-Cu nanocomposite particles and metal Cu nanoparticles are synthesized in a new microemulsion system which consists of saturated Cu(2+) salt aqueous solution dispersed in isopropanol and stabilized by polyvinylalcohol (PVA). The size of the composite particles and the thickness of the Cu(2)O shell layer can be controlled by the volume ratio of isopropanol to H(2)O (the ratio is defined as R). When R >/= 1000, it is available to obtain metal Cu nanoparticles. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Recombinant kringle IV-10 modules of human apolipoprotein(a): structure, ligand binding modes, and biological relevance.

The kringle modules of apolipoprotein(a) [apo(a)] of lipoprotein(a) [Lp(a)] are highly homologous with kringle 4 of plasminogen (75-94%) and like the latter are autonomous structural and functional units. Apo(a) contains 14-37 kringle 4 (KIV) repeats distributed into 10 classes (1-10). Lp(a) binds lysine-Sepharose via a lysine binding site (LBS) located in KIV-10 (88% homology with plasminogen K4). However, the W72R substitution that occurs in rhesus monkeys and occasionally in humans leads to impaired lysine binding capacity of KIV-10 and Lp(a). The foregoing has been investigated by determining the structures of KIV-10/M66 (M66 variant) in its unliganded and ligand [epsilon-aminocaproic acid (EACA)] bound modes and the structure of recombinant KIV-10/M66R72 (the W72R mutant). In addition, the EACA liganded structure of a sequence polymorph (M66T in about 42-50% of the human population) was reexamined (KIV-10/T66/EACA). The KIV-10/M66, KIV-10/M66/EACA, and KIV-10/T66/EACA molecular structures are highly isostructural, indicating that the LBS of the kringles is preformed anticipating ligand binding. A displacement of three water molecules from the EACA binding groove and a movement of R35 bringing the guanidinium group close to the carboxylate of EACA to assist R71 in stabilizing the anionic group of the ligand are the only changes accompanying ligand binding. Both EACA structures were in the embedded binding mode utilizing all three binding centers (anionic, hydrophobic, cationic) like plasminogen kringles 1 and 4. The KIV-10/T66/EACA structure determined in this work differs from one previously reported [Mikol, V., Lo Grasso, P. V. and, Boettcher, B. R. (1996) J. Mol. Biol. 256, 751-761], which crystallized in a different crystal system and displayed an unbound binding mode, where only the amino group of EACA interacted with the anionic center of the LBS. The remainder of the ligand extended into solvent perpendicular to the kringle surface, leaving the hydrophobic pocket and the cationic center of the LBS unoccupied. The structure of recombinant KIV-10/M66R72 shows that R72 extends along the ligand binding groove parallel to the expected position of EACA toward the anionic center (D55/D57) and makes a salt bridge with D57. Thus, the R72 side chain mimics ligand binding, and loss of binding ability is the result of steric blockage of the LBS by R72 physically occupying part of the site. The rhesus monkey lysine binding impairment is compared with that of chimpanzee where KIV-10 has been shown to have a D57N mutation instead.

Aminocaproic Acid↗
PubMed1999

Prolonged hypoxic stress increases adrenal cholesterol reserve in rats without causing adrenal hypertrophy.

1. It is known that, in rats, hypoxia stimulates adrenal steroidogenesis, but our understanding of the hypoxic effect on the glandular parameters remains incomplete. 2. Adrenals were collected and analysed from rats that had been exposed to hypoxic conditions for 3 weeks. 3. The results reveal increased adrenal concentrations of corticosterone, free cholesterol and total cholesterol without a change in glandular weight and protein concentration. The increased total cholesterol is primarily associated with enriched cholesteryl adrenate (CE22: 4), cholesteryl arachidonate (CE20: 4) and cholesteryl oleate (CE18: 1).

Adrenal Cortex↗