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Biomedical subjects

M Zhao

Publications and source records attributed to M Zhao.

At least 343 records · Page 19Linked to original sources
PubMed1990

Thymosin-like peptides as potential immunostimulants. Synthesis via the polymeric-reagent method.

This paper reports our attempt at designing new immunostimulating peptides which are chemically related to the bioactive peptides thymosin alpha 1 and thymopentin. Three peptides were synthesized, Asp-Leu-Lys-Glu-Arg-Lys-Asp-Val-Tyr (3), Arg-Lys-Asp-Val-Tyr-Glu-Glu-Ala-Glu-Asn (2), and Asp-Leu-Lys-Glu-Arg-Lys-Asp-Val-Tyr-Glu-Glu-Ala-Glu-Asn (1), each of which contains the thymopentin sequence and portions of the bioactive sequence of thymosin alpha 1. Peptides 1-3 were assembled from selected blocked fragments that were synthesized by the polymeric-reagent method, using PHBT (polystyrene-bound 1-hydroxybenzotriazole) as the activating polymer. The ability of peptides 1-3 to enhance the activation (RNA synthesis) and proliferation (DNA synthesis) of human T lymphocytes was determined. In comparison to thymosin alpha 1, thymosin alpha 1 (15-28), and thymopentin, peptides 1-3 did not show significant enhancement of these processes.

Amino Acid Sequence↗
PubMed1990

[The biotransformation of cui xing ning in the isolated perfused rat liver].

Similar to eserine, Cui Xing Ning [CXN),5-(1,3,3-trimethylindoline) N, N-dimethyl carbamate] is a choline esterase (ChE) inhibitor. The biotransformation of CXN, which had been studied in vivo and in vitro unsuccessfully, was studied by using isolated perfused rat liver (IPL) method. Six metabolites of CXN from the perfusate were separated by HPLC, and identified with MS, 1HNMR or compared with the authentic compounds. Metabolite I is unchanged CXN, the other are oxidized metabolites. Most of the metabolites lost their activities of ChE inhibition strikingly except metabolite III which retained the 2-position unchanged. The toxicities of some metabolites (II,V) decreased obviously.

Alkaloids↗
PubMed1990

Virological survey of rhesus monkeys in China.

A virological survey of rhesus monkeys captured in China for 13 viruses and/or antibodies was performed. Antigens used were SFV, SF40, HSV-1, Sa11, measles, vaccinia, epidemic or simian hemorrhagic fever, Langat, Kunming, poliomyelitis, HIV, SV41 and rubella. Monkeys were from Sichuan, Hunan, Guizhou, Yunnan and Guangxi provinces. Antibody was detected to all the listed viruses except HIV, SV41 and rubella. Both SFV and SV40 were recovered from monkeys, but H. simiae, LCM and coxsackieviruses were not.

Animals↗
PubMed1989

Extraterrestrial amino acids in Cretaceous/Tertiary boundary sediments at Stevns Klint, Denmark.

Since the discovery nearly a decade ago that Cretaceous/Tertiary (K/T) boundary layers are greatly enriched in iridium, a rare element in the Earth's crust, there has been intense controversy on the relationship between this Ir anomaly and the massive extinction of organisms ranging from dinosaurs to marine plankton that characterizes the K/T boundary. Convincing evidence suggests that both the Ir spike and the extinction event were caused by the collision of a large bolide (greater than 10 km in diameter) with the Earth. Alternative explanations claim that extensive, violent volcanism can account for the Ir, and that other independent causes were responsible for the mass extinctions. We surmise that the collision of a massive extraterrestrial object with the Earth may have produced a unique organic chemical signature because certain meteorites, and probably comets, contain organic compounds which are either rare or non-existent on the Earth. In contrast, no organic compounds would be expected to be associated with volcanic processes. Here we find that K/T boundary sediments at Stevns Klint, Denmark, contain both alpha-amino-isobutyric acid [AIB,(CH3)2CNH2COOH] and racemic isovaline [ISOVAL, CH3CH2(CH3)CNH2COOH], two amino acids that are exceedingly rare on the Earth but which are major amino acids in carbonaceous chondrites. An extraterrestrial source is the most reasonable explanation for the presence of these amino acids.

Amino Acids↗
PubMed1989

ACE inhibitors in acute and chronic ischaemia: current status and future promise.

1. Myocyte loss, reactive hypertrophy, dynamic ischaemia with 'stunning', and ventricular wall remodelling are all involved in the initiation and progression of myocardial failure which is ischaemic in origin. 2. The effects of ACE inhibitors to reduce preload and afterload has potentially salutary effects in these settings. Moreover, sulphyl containing ACE inhibitors may have further actions in reducing free radicals and their damage in the acute phases of these events. 3. These promising initial studies warrant further exploration.

Acute Disease↗
PubMed1989

The effect of IABP ventricular contractility of the normal and ischemic canine heart assessed in situ by T-Emax.

The effects of IABP on the contractile state of the in situ canine heart was evaluated under control conditions and conditions of regional ischemia by determining the transient slope of the end-systolic pressure-volume line, T-Emax. For comparison, the conventional index reflecting contractility, dP/dtmax and other related hemodynamic parameters were also assessed. The results showed that, T-Emax, rather than dP/dtmax, reflected more appropriately the changes in contractile state during activation of the IABP under both conditions. It suggests that IABP has a positive inotropic influence only in the ischemic-state and this is a positive inotropic influence only in the ischemic-state and this is a result of the improvement in the myocardial oxygen supply and demand relation. In addition, the limitations of the new indicator, T-Emax, is discussed.

Animals↗
PubMed1987

[Different effects of selenium on proliferation of human lung adenocarcinoma cells and human embryonic lung diploid cells in vitro].

After treating human lung adenocarcinoma cells by Na2SeO3 (1 microgram/ml) for 24 hours, its mitotic index decreased by 50%. The reduction rate was directly proportional to selenite concentration (1-5 micrograms/ml). In the meantime, the labelling index, growth rate and progression of the cell cycle were also inhibited. In contrast to the above observation, there was no marked change in the cell count, mitotic index, labelling index and the average silver granule number in the human embryonic lung diploid cells treated by Na2SeO3 (1-5 micrograms/ml) for 1-3 days. When human embryonic lung diploid cells were mix-cultured with human lung adenocarcinoma cells in the presence of 5 micrograms/ml Na2SeO3 for 24 hours, the former maintained a normal morphology, while the lung cancer cells showed heavily vacuolated cytoplasms and distorted nuclei.

Adenocarcinoma↗
PubMed1986

[Level of cyclic AMP-dependent protein kinase isozyme in normal liver and hepatoma tissue and the effect of sodium selenite].

Sodium selenite in normal saline was administered intraperitoneally (1 mg/kg) into mice bearing ascitic hepatocarcinoma for 4 days. The cyclic AMP-dependent protein kinase isozymes (type I and type II) in normal liver and hepatocarcinoma cells were separated and assayed. The results show that the level of type I/II is markedly higher in hepatocarcinoma than in the normal liver cells. Sodium selenite is able to reduce it towards the normal level. Further analysis shows that the chief function of sodium selenite is to reduce the raised level of type I/II in hepatocarcinoma cells which, in fact, is due to the increase of total amount of type I cyclic AMP-dependent protein kinase. This paper presents the speculation that one of the mechanisms of the inhibitory effect of sodium selenite on carcinogenesis may be due to the selective action of this compound on the cyclic AMP-dependent protein kinase isozymes in tumor cells, thus inhibiting cancer cell division and facilitating differentiation and reversion.

Animals↗