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Biomedical subjects

G Yu

Publications and source records attributed to G Yu.

At least 271 records · Page 15Linked to original sources
PubMed1991

[Analysis of the curative effect of partially accommodative esotropia in children].

Partially accommodative esotropia in children is due to accommodative factor in addition to anatomical factor. The former is corrected with spectacles, whereas the latter must be surgically treated. The authors handled 75 such cases by first prescribing spectacles for full correction of hyperopia, and surgical operations were performed to the residual esotropia after wearing the spectacles for 6 months. Patients surgically under-corrected were advised to wear over-correction spectacles, and patients surgically over-corrected to wear under-correction spectacles. Skiascopic examinations were done every 6 months; the physiological hyperopia decreased year by year, and the strength of hyperopic spectacles was decreased accordingly.

Accommodation, Ocular↗
PubMed1991

Effect of propionyl carnitine on energy charge and adenine nucleotide content of cardiac endothelial cells during hypoxia.

Adenine mucleotide metabolism is very active in endothelial cells. These cells are very rich in xanthine oxidase which may produce oxygen reactive species during ischaemia and reperfusion when a high amount of adenine nucleotides may be catabolized to hypoxanthine. We investigated the effect of propionyl carnitine on energy charge and nucleotide content in cultured endothelial cells during changes in oxygen partial pressure. During hypoxia the adenine nucleotide pool and the energy charge decreased more slowly in the presence of 0.5 mM propionyl carnitine than in the absence of the compound. Furthermore during reoxygenation a more rapid increase of energy charge and adenine nucleotide concentration was observed with propionyl carnitine. These observations suggest that the presence of propionyl carnitine allows the endothelial cells to maintain their functionality and regulatory role on vessel activity for a longer time and decreases the formation of oxygen reactive species due to xanthine oxidase activity on hypoxanthine formed by adenine nucleotide catabolism.

Adenine↗
PubMed1991

Protective effect of propionyl carnitine against peroxidative damage to arterial endothelium membranes.

Endothelial cells may be damaged by oxygen reactive species produced by granulocytes, by transition metal ions or by xanthine oxidase, an enzyme present in great quantity in these cells. Since it has been observed that propionyl carnitine protects the heart from peroxidation, we have investigated the effect of this compound on the formation of thiobarbituric acid reactive oxidation products (TBAR) in endothelial membranes. The peroxidation systems used were a mixture of Fe3+ and Fe2+, hydrogen peroxide and Fe2+, or xanthine oxidase-- xanthine. Propionyl carnitine at millimolar concentrations decreases TBAR formation. The protection is concentration-dependent and is almost absent in the presence of propionate and carnitine. From these results it appears that propionyl carnitine may protect not only myocardium but also vessels from peroxidative damage that occurs during ischaemia and reperfusion.

Animals↗
PubMed1990

Safety and efficacy of sotalol in patients with drug-refractory sustained ventricular tachyarrhythmias.

The safety and efficacy of oral sotalol, an investigational beta-adrenergic blocker with class III antiarrhythmic drug properties, were examined in a multicenter study in 236 patients with sustained ventricular tachyarrhythmias. In 104 patients, the index arrhythmia was a cardiac arrest, and all patients had undergone at least 3 previous unsuccessful antiarrhythmic trials (mean = 5 per patient). In the 106 patients assessed by programmed electrical stimulation, sotalol completely suppressed induction of ventricular tachycardia (VT) in 33 (31%) and rendered VT slower (greater than 100 ms prolongation of cycle length) or more difficult to induce in 29 (27%). Using continuous 24-hour ambulatory monitoring methods, sotalol complete- and partial-response rates were 51 and 12%, respectively. Of the 236 acute-phase patients, 151 were discharged receiving long-term sotalol therapy. The median sotalol dose was 480 mg/day. At a mean follow-up of 346 +/- 92 days, 27 patients (18%) had recurrence of sustained arrhythmia; 9, sudden death; 11, sustained VT; 5, automatic defibrillator discharge; and 2, syncope. Adverse effects forced discontinuation of therapy in 10 patients (7%): 6 secondary to symptomatic bradyarrhythmia, 2 due to refractory heart failure, 1 due to torsades de pointes, and 1 from bronchospasm. Life-table analysis of sotalol's overall long-term efficacy at 6, 12 and 18 months were 80, 76 and 72%, respectively. Although mean follow-up was short (less than 1 year), neither acute-phase programmed stimulation nor 24-hour ambulatory monitoring responses were significantly predictive of subsequent arrhythmic outcome. Proarrhythmia was documented in 18 patients (7%), 17 during the acute phase and 1 during long-term follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1990

Photochemotherapy alone or combined with interferon alpha-2a in the treatment of cutaneous T-cell lymphoma.

Eighty-two patients with either mycosis fungoides (MF) or parapsoriasis en plaques were treated with psoralens ultraviolet A light (PUVA). Clinical and histologic parameters were followed for a period from 6 months to 10 years. Complete clinical clearing of lesions was observed in 51 patients (62%) and most of them were in limited-plaque MF group or parapsoriasis en plaque. The mean total dose of PUVA for complete clearing was less for early MF. Thirty-one patients (38%) relapsed and responded to additional PUVA. Patients in early stages of the disease remained clear for up to 68 months after the first course of PUVA. Post-treatment skin biopsies with early MF showed histologic clearing. A new combination therapy for MF is presented in 15 patients. Recombinant interferon alpha-2a (Roferon-A), administered intramuscularly combined with PUVA were tested in a phase I trial. Interferon doses were from 6-30 million units three times weekly. Disease stages ranged from I-B to IV-B. Complete responses were obtained in 12 of 15 patients, and partial responses seen in 2 of 15 patients, for an overall response rate of 93%. The median duration of response exceeded 23 months (range, 3 to 25 months). All responding patients have been maintained on therapy. The dose-limiting toxicities were constitutional symptoms such as fevers and malaise (93.3%), leukopenias (40.0%), mental status changes consisting of depression and confusion (33.3%), and photosensitivity (26.6%). Interferon plus PUVA appear to be highly effective regimens for the treatment of patients with cutaneous T-cell lymphomas.

Adult↗
PubMed1990

[Investigation on resources of the Chinese drug beimu in Gansu Province].

Based on a resources investigation and taxonomic research on the medicinal plants of Fritillaria from Gansu Province. Nine species one variety and one cultivation variety have been reported. Records and distribution of the species, together with a key for the species and a key for the powdered drug have been furnished as well.

China↗
PubMed1990

[Optimal potassium concentration in cardioplegic solutions].

A model of perfused cardiac papillary muscle from guinea pig was set up in our lab. The procaine-free St. Thomas' Hospital solution was used as the basic cardioplegic solution. The potassium concentration of the solution was designed by optimization (14.6, 22.8, 28.5, 32.6, 57.8 mmol/L). The papillary muscle was undergone anoxic arrest for 60 min in 32 degrees C. The effect of myocardium preservation was assessed with cardiac action potential, contractility and quantitative analysis of ultrastructure. We concluded that; (1) in this research the proper potassium concentration is at the range of 20.7-26.0 mmol/L and the optimal one is 22.8 mmol/L; (2) despite any deviation from the range, phases II and III of the action potential changes first. [K+] greater than or equal to 32.6 mmol/L slows conductivity, weakens contractility and damages the subcellular structure severely; (3) if [K+] is 57.8 mmol/L, anoxic arrest for 60 minutes in 32 degrees C damages of both structure and function of myocardium is irreversible; (4) following the hyperkalemic cardioplegia, there is a secondary change of cardiac action potential in reperfusion period, which shows longer phase II and shorter phase III, smaller Vmax and APA; (5) reperfusion arrhythmia after anoxic hyperkalemic asystole is likely caused by all kinds of conductive disorders resulting from the secondary changes of action potential; (6) arrest time, AT (Y, s) has the negative relativity to the potassium concentration (X, mmol/L) of cardioplegic solution, which can regress to curve 1/Y = 0.10-1.38/X(14.6 less than or equal to X less than or equal to 57.8). The minimum potassium concentration which can guarantee AT within 30 seconds is 20.7 mmol/L.

Action Potentials↗
PubMed1989

Membrane anchoring of a human IgG Fc receptor (CD16) determined by a single amino acid.

CD16 is a low-affinity immunoglobulin G (IgG) Fc receptor that is expressed on natural killer (NK) cells, granulocytes, activated macrophages, and some T lymphocytes. Two similar genes, CD16-I and CD16-II, encode membrane glycoproteins that are anchored by phosphatidylinositol (PI)-glycan and transmembrane polypeptides, respectively. The primary structural requirements for PI-linkage were examined by constructing a series of hybrid cDNA molecules. Although both cDNA's have an identical COOH-terminal hydrophobic segment, CD16-I has Ser203 whereas CD16-II has Phe203. Conversion of Phe to Ser in CD16-II permits expression of a PI-glycan-anchored glycoprotein, whereas conversion of Ser to Phe in CD16-I prevents PI-glycan linkage.

Animals↗
PubMed1989

Co-association of CD3 zeta with a receptor (CD16) for IgG Fc on human natural killer cells.

Natural killer (NK) cells are a subset of lymphocytes that mediate major histocompatibility complex (MHC)-nonrestricted cytotoxicity against tumours and virus-infected cells and secrete numerous cytokines on activation. NK cells are distinct from mature T lymphocytes, because they do not rearrange or productively transcribe T-cell receptor alpha-, beta-, gamma- or delta-chain genes and do not express the CD3 gamma- or delta-subunits. But recent studies indicate that NK cells do express CD3 zeta, co-associated with other membrane proteins. Here we report that CD16, the receptor for the Fc (constant) region of IgG, specifically associates with the CD3 zeta homodimer on the membrane of human NK cells, and that co-transfection with CD3 zeta complementary DNA permits expression of a transmembrane-linked CD16 complex on COS-7 cells. These findings indicate that CD3 zeta can co-associate with membrane receptors of diverse cell types and function as a common structure for signal transduction.

Antigens, CD↗
PubMed1989

K562 leukemia cells transfected with the human c-fes gene acquire the ability to undergo myeloid differentiation.

Expression of the proto-oncogene p93c-fes and its associated tyrosine kinase activity is marked in mature granulocytes, monocytes, differentiated HL-60 leukemia cells, and leukemia cell lines KG-1, THP-1, HEL, and U-937, which can be induced to differentiate along the granulocyte/monocyte pathway. Conversely, p93-c-fes expression is absent in the K562 cell line, which is resistant to myeloid differentiation. Upon transfection and clonal selection of K562 cells using a mammalian expression vector containing the 13-kilobase pair c-fes gene, c-fes mRNA was transcribed and p93-c-fes tyrosine activity kinase was expressed. Clones expressing c-fes underwent myeloid differentiation as assessed by the appearance of phagocytic activity, Fc receptors, nitro blue tetrazolium reduction, Mac-1 immunofluorescence, and lysozyme production. These results indicate that the expression of the c-fes protooncogene and its associated tyrosine kinase activity plays a major role in the initiation of myeloid differentiation.

Animals↗
PubMed1989

A clinical investigation with Holter's monitoring of the antiarrhythmic effect of adonisidum.

The authors studied 24 cases of refractory premature beats by giving 0.1 adonisidum twice daily with Holter's monitoring. It was found that adonisidum was effective in 12 cases (P less than 0.001), or 50%. In another 8 patients adonisidum or mexiletine alone were ineffective for premature beats. However, when these patients were treated with both mexiletine and adonisidum, they responded with no exception (P less than 0.001). All 7 cases monitored with one hour Holter recording responded to adonisidum (P less than 0.001). As adonisidum tends to slow the heart rate, it is especially indicated for patients suffering from premature beats with increased heart rate, and should be used with caution in cases with slow heart rate or A-V block.

Adolescent↗
PubMed1989

[The surgical treatment of intermittent exotropia].

77 cases of surgically treated intermittent exotropia were followed up for analysis with regard to the relation between the age of operation and curative effect, the age and post-operative restoration of homologous retinal correspondence, and the effect of over-correction on final orthophoria. The authors were of the opinion that the earliest surgical intervention was conducive to recovery of Grade III visual function and restoration of homologous retinal correspondence, and slight over-correction was significant for final orthophoria. They recommended that the earliest surgical intervention be accorded patients with intermittent exotropia of 20 delta and over, instead of purposeless waiting and observation.

Adolescent↗