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Biomedical subjects

R Zhang

Publications and source records attributed to R Zhang.

At least 505 records · Page 28Linked to original sources
PubMed1992

Estimation of respiratory mechanics in dogs with acute lung injury.

In mechanically ventilated anesthetized dogs with acute lung injury induced by intravenous infusion of oleic acid (OA), changes in airflow, lung volume, and tracheal (Pao), transpulmonary (Ptp) pressures were measured. Changes in lung mechanics were studied before and after OA infusion at intervals, during an observation period lasting 4-5 hours, by using the interrupter technique and identification technique, and by measuring the pressure-volume (PV) characteristics. The main results are listed as follows: (1) compliance and FRC showed a marked decrease, Pao and Ptp showed a marked increase within 2 hours after OA. (2) airflow resistance estimated by the identification technique showed a marked increase after OA. (3) static PV characteristics of both the lungs and total respiratory system showed similar changes 4 hours after OA, characterized by the presence of an inflexion on the inflation limb, increased hysteresis and a rightward and downward shift of the loop. (4) the trend of changes of dynamic PV characteristics obtained by changing the PEEP value in a stepwise manner, with the ventilation uninterrupted, was similar to that of the static PV curve. It is suggested that an on-line identification technique with one-compartment model to track the slow changes in combination with serial measurements of the dynamic PV characteristics of the total respiratory system would be more appropriate for monitoring lung mechanics of ventilated patients with ARDS.

Animals↗
PubMed1992

[A method for acquiring newborn larvae of Trichinella spiralis in vitro].

This paper reports a simple method for acquiring numerous newborn larvae of Trichinella spiralis in vitro. Adults of T. spiralis, collected from small intestine on rats which were infected with infective larvae separated from mice infected experimentally, were put into tissue culture bottle containing M199. Then the bottles were incubated in CO2 incubator (37 degrees C, 5% CO2) for 15-20h. The newborn larvae were collected by passing through filtration, centrifugation and repeated wash. The results showed that this method is effective in terms of the activity of the adults and newborn larvae and the amount of larvae gained. The method in economical and can control bacterial contamination to a certain extent and extract ES antigen of adults and newborn larvae from the culture solution.

Animals↗
PubMed1992

A novel monoclonal antibody to cytokeratin 18 with reactivity toward lung squamous cell carcinomas and adenocarcinomas of various sites.

Antibodies to cytokeratins (CKs) have found extensive application in the differential diagnosis of epithelial tumors. The chain-specific anti-CK reagents appear to be of practical value for further subtyping of carcinomas. The authors have produced a novel anti-CK 18 monoclonal antibody (ACK-156) using a modified immunization procedure that included sequential injections of human epidermal keratin, cyclophosphamide, and enriched cytoskeletal extracts from a human lung carcinoma cell line. This protocol effectively amplified clones with reactivity toward CK epitopes not present in epidermal keratin. Monospecificity of the antibody was confirmed by immunoblot analysis using both total cell lysates and cytoskeletal extracts as antigens. Immunoperoxidase staining of adenocarcinomas from a variety of sites, including lung, was strongly positive. Squamous cell carcinomas of lung were also strongly stained whereas squamous cell carcinomas of head and neck origin were stained focally or not at all. In contrast, several commercially available anti-CK 18 monoclonal antibodies did not distinguish squamous cell carcinomas of lung from those of head and neck origin. Immunoblot analysis of tumor lysates corroborated the tissue staining results and revealed that the commercially available antibodies that were tested recognize at least one other low molecular weight peptide in addition to the CK 18 peptide recognized by ACK-156.

Adenocarcinoma↗
PubMed1992

[Chemistry and immunochemistry analysis of the soluble antigens of newborn larvae of Trichinella spiralis].

The soluble antigens of newborn larvae of Trichinella spiralis were characterized in terms of molecular weight of protein, glycoprotein and lipoprotein contents, and immunochemistry. After the antigens were separated with SDS-PAGE and then followed by ultrasensitive silver staining, at least 40 bands of proteins were noted. Correspondingly, 28 bands of glycoproteins and 9 bands of lipoproteins were revealed as the similar gels were stained by the hypersensitive periodic acid silver and Nile's blue staining respectively. Six specific bands were recognized using polyclonal antibodies in the serum of rabbits immunized with antigens of newborn larvae by immunoblotting. All of them are glycoproteins. The components of the antigens with molecular weight (MW) 41.5 kd, 40 kd, 29.5 kd, 25 kd, 11 kd and 18 kd were found to be species specific and newborn larva stage-specific target antigen relevantly.

Animals↗
PubMed1992

[The application of circular dichroism on the structure analysis of natural products--diterpenoid dilactones and tylophorines].

In this paper, circular dichroism (CD), sector projection and reverse octant rule projection of four diterpenoid dilactones and five tylophorines (two of them, 6, 8, are new compounds) are reported in which reverse octant rule projection is the first application to the configuration determination of diterpenoid dilactone. By using these rules, the predicted Cotton effects of these compounds coincided with the result of previous determinations, so, their absolute configurations are assigned.

Alkaloids↗
PubMed1992

[Identification of morphology and inorganic elements of Eucommia ulmoides Oliv. produced in Sichuan by applying scanning electron microscope with energy dispersive X-ray analysis].

A research on the identification of morphology and inorganic elements of Eucommia ulmoides produced in Sichuan has been made by applying scanning electron microscope; energy dispersive X-ray analysis. Qualitative and semi-quantitative analyses of the inorganic elements in the observed areas have been obtained.

Calcium↗
PubMed1992

[A preliminary study on growing tempo of Ophisourus harti Boulenger].

Under experimental circumstances, the relationship between the growing tempo of Ophisourus harti and its age, fodder, outside temperature and humidity has surveyed. Suggestions have accordingly been made with regard to the rational utilization and protection of the resources.

Animal Feed↗
PubMed1992

Skin test inhibition by astemizole.

For the purpose of evaluating the therapeutic effect of antihistamines, we have set up an assay method called the "Skin Test Inhibition Index" (STII). Twenty subjects with hay fever were given astemizole (10 mg/d) for 7 days. Skin titration tests were carried out before and after treatment. Significant inhibition of the skin test reaction by astemizole was demonstrated (STII = 91). Another group of 6 hay fever patients was given astemizole (10 mg/d) for 10 days, and STII was determined on days 5 and 10 and on days 7, 14 and 21 after treatment. STII were calculated as 12, 108, 90, 10 and 7, respectively. These results demonstrate that astemizole is a long-acting antihistamine.

Adult↗
PubMed1992

[Revision of structure of peimisine].

From the bulbs of Fritillaria siechuanica cultivated in Sichuan province, 5 alkaloids including peimisine (III) were isolated. Structure of peimisine reported in reference (2) was revised as 2 based on 2D-NMR (1H-1H, 1H-13C COSY and NOE), and FR-5 was proved to be peimisine on the basis of their melting point and TLC behavior. It is worthy of noting that 1) configuration of the oxygen at the C-17 in hupehenisine 3 is possibly erroneous; 2) both songbaisine 4 (A or B) and peimisine 2 should be the same compound on the basis of comparison of their 13C NMR data (Table 3) and 1H NMR spectra; 3) configuration of the oxygen atom at C-17 in the jervine-type steroidal alkaloids can not be safely proved by their IR, MS and the chemical shifts of some protons such as the methyls without the X-ray diffraction analysis, or the NOE technique and the 13C NMR method.

Alkaloids↗
PubMed1992

[Reversed phase high performance liquid chromatography of tetracyclines].

The present paper describes a quantitative determination method of tetracyclines by reversed phase high performance liquid chromatography. The method used a Waters 10 C18 4.6 nm ID x 250 nm reversed phase column, with a mobile phase composed of 14% acetonitrile-3% dimethylformamide-83% water containing 0.02 mol/L citric acid (pH-2.5), the detector wavelength was set at 350 nm, and the flow rate was maintained at 1.0 ml/min. Demethylchlortetracycline, epi-demethylchlortetracycline, demethyltetracycline, epi-demethyltetracycline, tetracycline, epi-tetracycline, chlortetracycline and epi-chlortetracycline can be separated highly efficiently. The tetracyclines and their anhydro- products can be separated on the same column with 15% acetonitrile- 15% dimethylformamide- 70% 0.02 mol/L citric acid as the mobile phase, and detected at UV 270 nm.

Chromatography, High Pressure Liquid↗
PubMed1992

[An ultrastructural dynamic study of trophoblast cells in human placenta].

Sixty-seven specimens of human placentae aged 5 to 41 weeks were collected and their trophoblastic cells studied dynamically under EM. Two kinds of cells, dark cytotrophoblasts and transitional syncytial trophoblasts were observed. Trophoblast fusion was also observed, and this phenomenon may have been related to the aggregation of syncytial cell nuclei and the formation of syncytial knots. During pregnancy, trophoblasts (especially syncytial trophoblasts) showed dynamic changes which were more prominent in the nuclei, including increased heterochromatin content and nuclear aggregation.

Female↗
PubMed1991

Changes in binding activity of luteinizing hormone receptors by site directed mutagenesis of potential glycosylation sites.

Site directed mutagenesis of the rat ovarian luteinizing hormone (LH) receptor cDNA was performed at each of the six potential N-linked glycosylation sites to determine the effect of putative carbohydrate chains on the activity of the membrane receptor. The conversion of Asn173 to Gln resulted in the total loss of hormone binding to the surface of the transfected cell. Mutant receptors synthesized with substitutions at the remaining potential N-linked glycosylation positions of 77, 152, 269, 277 and 291 revealed no significant change in the hormone affinity. However Asn77Gln and Asn152Gln exhibited significant decreases (approximately 80%) in the number of high affinity hormone binding sites. The changes in hormone binding activity upon elimination of the potential glycosylation sites at 77, 152 and 173 indicate the presence of functional carbohydrate chains at these positions in the rat ovarian LH/hCG receptor.

Animals↗
PubMed1991

Analysis of distribution of bases in the coding sequences by a diagrammatic technique.

The frequencies of occurrence of four bases in the first, second and third codon positions and in the total coding sequences have been calculated by the codon usage table published in 1990 by Ikemura et al. The distribution of frequencies are further analysed in detail by a graphic technique presented recently by us. Formulas expressing the frequencies of four bases in the first and second codon positions in terms of frequencies of amino acids have been given. It is shown by the graphic analysis that for 90 species, in the first codon position the purine bases are dominant and in most cases G is the most dominant base. In the second codon position A is the most dominant base, while G is the least dominant base. In the third codon position the G + C content varies from 0.1 to 0.9, keeping the A + C content equal to 1/2 and G content equal to that of C, approximately. If the frequencies for bases A, C, G and U in the total coding sequences are denoted by a, c, g and u, respectively, it is found that the unequal formula: a2 + c2 + g2 + u2 less than 1/3, is valid for each of the 90 species including the human and E.coli etc.

Base Sequence↗
PubMed1991

A clinical and experimental study on all-trans retinoic acid-treated acute promyelocytic leukemia patients.

Fifty patients with acute promyelocytic leukemia (APL) have been treated with all-trans retinoic acid (RA). In vitro induced differentiation of primarily cultured bone marrow cells from the patients, colony-forming unit granulocyte-macrophage (CFU-GM) and L-CFU colony-forming assays, and karyotype analysis were performed over the treatment course. The very high bone marrow complete remission (CR) rate (94%) suggested that all-trans RA was superior to conventional chemotherapeutic regimens for the treatment of APL. The leukemic clone was reduced by RA-induced terminal differentiation and loss of proliferation capacity of leukemic cells. Relapse after CR in about 40% of patients was the major reason for the failure of the RA treatment. Patients who relapsed after a chemotherapy-maintained CR could be effectively reinduced to second CR by RA. However, if relapse occurred after a CR maintained by both RA and chemotherapy, the sensitivity of newly emerged leukemic clones to RA was greatly reduced. Therefore, it is suggested that RA should be replaced by conventional chemotherapy as soon as CR is achieved. Laboratory studies proved valuable in selecting cases for RA therapy and in predicting therapeutic effects and prognosis.

Adolescent↗
PubMed1991

Diagrammatic representation of the distribution of DNA bases and its applications.

The frequencies of occurrence of the bases A, C, G and T (or U) in a DNA or mRNA sequence are denoted by a, c, g, t (or u), respectively. Since a + c + g + t = 1, the four real numbers are mapped into a point within a regular tetrahedron. The mapping points are then projected to some planes for further study. We have given several examples of application of this technique. As a by-product of an application we have found an empirical formula on the limit distribution of DNA bases for different kind of organisms, i.e. 1/4 less than or equal to a2 + c2 + g2 + t2 less than 1/3.

Adenine↗
PubMed1991

Evidence from oocyte expression that the erythrocyte water channel is distinct from band 3 and the glucose transporter.

It has been proposed that the mercurial-sensitive water transporter in mammalian erythrocytes is the anion exchanger band 3 (AE1) and/or the glucose transporter, band 4.5 (GLUT1). Using a functional assay for water channel expression in Xenopus oocytes (Zhang, R., K. A. Logee, and A. S. Verkman. 1990. J. Biol. Chem. 265:15375-15378), we compared osmotic water permeability (Pf) of oocytes injected with water, reticulocyte mRNA, AE1 mRNA, and GLUT1 mRNA. Injection of oocytes with 5-50 ng of in vitro-transcribed AE1 mRNA had no effect on Pf, but increased trans-stimulated 36Cl uptake greater than fourfold in a dinitro-disulfonic stilbene (DNDS)-inhibitable manner. Injection with 1-50 ng of in vitro-transcribed GLUT1 mRNA increased 3H-methylglucose uptake greater than 15-fold in a cytochalasin B-sensitive manner and increased Pf from (3.7 +/- 0.4) x 10(-4) cm/s (SE, n = 16, 10 degrees C) in water-injected oocytes up to (13 +/- 1) x 10(-4) cm/s (n = 18). Both the increments in sugar and water transport were inhibited by cytochalasin B (25 microM) and phloretin (0.2 mM); neither was inhibited by 0.3 mM HgCl2. In oocytes injected with 50 ng of rabbit reticulocyte mRNA, the Pf of (18 +/- 2) x 10(-4) cm/s (n = 18) was reduced to (4.0 +/- 0.6) x 10(-4) cm/s (n = 10) by HgCl2, but was not inhibited by DNDS (0.4 mM), cytochalasin B or phloretin. Coinjection of reticulocyte mRNA with antisense oligodeoxyribonucleotides against AE1 or GLUT1 did not affect Pf, but inhibited completely the incremental uptake of 36Cl or 3H-methylglucose, respectively. Expression of size-fractionated mRNA from reticulocyte gave a 2-2.5-kb size for water channel mRNA, less than the 4-4.5-kb size for the Cl transporter. These results provide evidence that facilitated water transport in erythrocytes is mediated not by bands 3 or 4.5, but by distinct water transport protein(s).

Animals↗