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Biomedical subjects

F Li

Publications and source records attributed to F Li.

At least 613 records · Page 34Linked to original sources
PubMed1989

[Studies on the relation of alkaloids in semen Strychni and its processing].

This paper reports the determination of strychnine and brucine in different parts of Semen Strychni (the seeds of Strychnos nux-vomica and S. pierriana), and makes a comparison of the contents between the crude forms and processed products of the two seeds. Based on the results, the authors have made some discussion about the relationship between the alkaloid distribution in Semen Strychni and its processing.

Drugs, Chinese Herbal↗
PubMed1989

Serum antibodies to defined carbohydrate antigens during the course of treated leprosy.

Sequential monitoring of 724 sera for antibodies to a neoantigen based on phenolic glycolipid-I (PGL-I) and native lipoarabinomannan (LAM) in 90 leprosy patients undergoing therapy in San Francisco was conducted. Untreated lepromatous patients frequently (91%) had significant antibodies to both moieties. Antibodies were less frequently found in tuberculoid patients (74% to neoantigen and 37% to LAM). In the first 3 years of treatment, average serum antibodies to both moieties fell significantly. Antibodies to LAM fell during each of the first 4 years of therapy, but decreasing antibody levels to the PGL-I neoantigen did not appear to fall consistently after the third year of treatment. A wide variation in the rate of fall of serum antibodies was noted. Sequential changes in the amounts of serum antibodies to the neoantigen and LAM in general paralleled one another but were at times discrepant. Both in San Francisco and Malaysia, skin-smear negative, long-term treated, lepromatous leprosy patients frequently harbored significant antibodies to both PGL-I and LAM.

Antibodies, Bacterial↗
PubMed1988

Alteration of human lymphokine-activated killer cell activity by manipulation of protein kinase C and cytosolic Ca2+.

We have examined the effects of protein kinase C (PK-C) stimulation and cytosolic Ca2+ elevation on the in vitro induction of non-histocompatibility-restricted tumoricidal activity from human peripheral blood lymphocytes. The tumor cytolytic activity, as well as the number of cells recovered from interleukin 2 (IL-2)-stimulated cultures, was enhanced by the addition of the PK-C stimulator, phorbol dibutyrate (PDBu), but not non-PK-C-activating phorbol ester analogues while the Ca2+ ionophore, ionomycin, did not significantly alter development of IL-2-induced tumor cytolytic activity nor enhance cell yield. Neither PDBu nor ionomycin, alone or in combination, induced tumoricidal activity. The addition of both PDBu and ionomycin to recombinant interleukin 2 (rIL-2)-exposed cultures produced a strong mitogenic response and high cell yield, although Daudi cell killing measured at Day 5 was completely abolished. This abrogation of lymphokine-activated killer cell activity was seen as early as 24 h following exposure to PDBu and ionomycin, reaching 50% following 2 days of exposure. When lymphocytes mitogenically expanded by primary exposure to PDBu and ionomycin and then washed free of these agents were further cultured with rIL-2 alone, proliferation continued, and substantial cytolytic activity for Daudi cells was induced. The development of this postexpansion cytotoxic activity was not dependent on the addition of exogenous rIL-2 during the primary cultures. Fractionation of cells into large granular lymphocytes and small T-lymphocytes indicated that only the large granular lymphocytes proliferate in response to rIL-2 alone. Both large granular lymphocytes and small T-lymphocytes proliferate in response to the addition of PDBu and ionomycin, and both populations of cells developed tumor cytolytic activity following removal of PDBu and ionomycin and subsequent culture in rIL-2. These data suggest that PK-C and Ca2+ signals play key roles in the regulation and/or proliferation of tumor cytotoxic lymphocytes or their precursors and that manipulation of those signals can be utilized to produce substantially more tumoricidal activity from lymphocyte populations than can be achieved with rIL-2 alone.

Calcium↗
PubMed1988

Inhibition of DNA synthesis in primary cultures of hepatocytes by orotic acid.

Orotic acid has been shown to promote carcinogenesis in the liver and the intestine of the rat. In an attempt to determine whether orotic acid promotes liver carcinogenesis by creating differential mitoinhibition, experiments were designed to study the effect of orotic acid on the labeling index of isolated hepatocytes in response to epidermal growth factor. The results indicated that orotic acid added in vitro inhibited epidermal-growth-factor-induced labeling index of isolated hepatocytes. In addition, isolated hepatocytes from rats exposed to orotic acid under promoting conditions also exhibited a decreased response to epidermal growth factor. These data suggest that orotic acid may exert its promoting effect by differentially inhibiting the response of normal hepatocytes to one or more endogenous growth stimuli while permitting the initiated hepatocytes to respond to such stimuli and grow to form hepatic nodules.

Animals↗
PubMed1988

Changes in canine leukocyte glucocorticoid receptors during endotoxin shock.

We studied changes in canine leukocyte glucocorticoid receptors during endotoxin shock. Blood samples for analysis were collected and leukocytes were isolated just prior to and 2 and 6 hours after endotoxin administration. Employing 3H-dexamethasone (3H-Dex) as a ligand, we studied 3H-Dex-specific binding of the leukocytes in dogs and their changes during endotoxin shock. Results from two groups (anesthetized and conscious) showed that the specific binding of the leukocytes decreased significantly 2 hours after endotoxin administration in both groups and 6 hours after endotoxin in anesthetized dogs. In conscious dogs, the specific binding returned to normal by 6 hours. No correlation was found between the changes of serum cortisol and 3H-Dex-specific binding. It may be suggested that perturbations in glucocorticoid hormone action at the receptor level might be involved in the pathogenesis of endotoxin shock.

Animals↗
PubMed1987

High-performance liquid chromatography of type-III heptocarboxylic porphyrinogen isomers.

A reversed-phase h.p.l.c. system is described for the separation of the four type-III heptacarboxylic porphyrinogen isomers. The effects of buffer concentration, pH and type and proportion of organic modifier in the mobile phase on retention and resolution of isomers were studied. Optimum separation on an ODS-Hypersil column was by elution with a ternary mobile phase of acetonitrile, methanol and 1 M-ammonium acetate, pH 5.16 (7:3:90, by vol.). Isomer identification was based on a comparison of their retention times with those of authentic standards, and was further confirmed by h.p.l.c. analysis of the characteristic mixture of three pentacarboxylic porphyrins formed after partial decarboxylation of individual isomers in 0.3 M-HCl at 160 degrees C.

Acetates↗
PubMed1987

An h.p.l.c. assay for protoporphyrinogen oxidase activity in rat liver.

An h.p.l.c. method is described for the assay of protoporphyrinogen oxidase activity in rat liver. A relatively pure protoporphyrinogen IX substrate was obtained by selectively removing any protoporphyrin IX unreduced by sodium amalgam on a small disposable cartridge packed with a strong anion-exchanger. The protoporphyrin IX formed was extracted with dimethyl sulphoxide/methanol (3:7, v/v) containing mesoporphyrin as the internal standard for separation and quantification by reversed-phase chromatography. The Km for protoporphyrinogen was 9.5 +/- 1.6 microM, and the enzyme activities were 0.59 +/- 0.11 nmol of protoporphyrin IX produced/min per mg of mitochondrial protein and 33.5 +/- 2.7 nmol protoporphyrin IX produced/min per g of liver tissue homogenate. The method is applicable to the determination of enzyme activity in small amounts of human liver biopsy.

Animals↗
PubMed1987

Separation and characterization of pentacarboxylic porphyrinogen isomers by high-performance liquid chromatography with electrochemical detection.

A reversed-phase h.p.l.c. system is described for the separation of all five naturally occurring pentacarboxylic porphyrinogen isomers. The compounds are detected electrochemically with high sensitivity. The peaks are positively identified by h.p.l.c. analysis of the pentacarboxylic porphyrinogens from reduction of pentacarboxylic porphyrins prepared by partial decarboxylation of hexa- and hepta-carboxylic porphyrin III of known structures. The resolution of pentacarboxylic porphyrinogens is superior to that of the porphyrins and the method is applicable to the small-scale preparative isolation of pure isomers.

Animals↗
PubMed1987

Serotyping and subgrouping of some rotavirus strains in China.

This article reports for the first time in China the results of serotyping and subgrouping of some rotavirus strains obtained from faecal fluids of cases with infant diarrhoea. Infant diarrhoea rotavirus serotype 1 (Wa strain)-specific and serotype 2 (KUN strain)-specific hyperimmune sera, and infant diarrhoea rotavirus serotype 3-specific, rotavirus subgroup I-specific and subgroup II-specific monoclonal antibodies were used in serotyping and subgrouping by means of enzyme-linked immunosorbent assay of 14 rotavirus strains which had been identified by electron microscopy. Results showed that three out of four Beijing strains in 1982 belonged to serotype 2 and subgroup I rotavirus, one belonged to serotype 3 and subgroup II rotavirus; one out of nine Beijing strains in 1984 belonged to serotype 1 and subgroup II rotavirus, seven belonged to serotype 2 and subgroup I rotavirus, one belonged to serotype 3 and subgroup II rotavirus; and one Kunming strain in 1984 belonged to serotype 3 and subgroup II rotavirus.

Antibodies, Monoclonal↗
PubMed1987

Effect of hemoperfusion of cross-linked agarose coated activated charcoal (CAAC-II) on T-lymphocyte function in rats and guinea pigs.

Blood of rats and guinea pigs on cross-linked agarose coated activated charcoal (CAAC-II) hemoperfusion was analyzed over a follow-up period of 48 hours for the capacity of T-lymphocyte to transform under the stimulation of mitogen (PHA) in vivo and in vitro respectively. In the rate hemoperfusion, the in vivo T-lymphocyte transformation and lymphocyte count of peripheral blood were involved. In guinea pigs, the lymphocyte cultures were labelled with 3H-TdR and the radioactive incorporation was measured on the liquid scintillation counter. Our results revealed that the T-lymphocyte transformation function remained unchanged after 60-minute CAAC-II hemoperfusion although there was a transient and incomplete suppression of the T-lymphocyte transformation function both in vivo and in vitro immediately after the anesthesia and operation with blood vessel cannulation. The peripheral blood lymphocyte count also remained stable during the 60-minute CAAC-II hemoperfusion on rats and guinea pigs. We concluded that the charcoal hemoperfusion can be used as an important method of treatment for drug intoxication, uremia and hepatic coma with no harm to the body's immune function.

Animals↗
PubMed1986

Assaying erythrocyte haem biosynthetic enzyme activities by high-performance liquid chromatography with the advanced automated sample processor.

The four cytosolic haem biosynthetic enzymes in erythrocytes were assayed with the Varian advanced automated sample processor (AASP) for rapid sample concentration and clean-up with fast and effective high-performance liquid chromatography systems for separation and quantitation. In the assay for 5-aminolaevulinic acid dehydrase, the porphobilinogen (PBG) formed was extracted on a C18 AASP cartridge and separated by reversed-phase ion-pair chromatography with 32% methanol in 0.05 M sodium acetate buffer (pH 3.5), containing 5.4 mM of 1-heptane-sulphonic acid as eluent. PBG was the substrate for the simultaneous assay of hydroxymethylbilane synthase and uroporphyrinogen III synthase. The uroporphyrinogen I and III isomers formed were oxidised to porphyrins, concentrated on a C2 or C8 cartridge, and separated by reversed-phase chromatography with 13% acetonitrile in 1 M ammonium acetate buffer (pH 5.16) as eluent. Uroporphyrinogen decarboxylase was estimated with pentacarboxylic porphyrinogen III as substrate. The coproporphyrinogen formed was extracted on a C2 or C8 cartridge, oxidised to coproporphyrin and separated by reversed-phase chromatography with 30% acetonitrile in 1 M ammonium acetate buffer (pH 5.16) as mobile phase.

Ammonia-Lyases↗