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Biomedical subjects

D Liu

Publications and source records attributed to D Liu.

At least 775 records · Page 43Linked to original sources
PubMed1991

Excitatory amino acids rise to toxic levels upon impact injury to the rat spinal cord.

The release of glutamate, aspartate, glutamine and asparagine upon impact injury to the rat spinal cord was characterized by sample collection from the site of injury by microdialysis. Injury caused dramatic and long-lasting increases in the concentrations of the excitatory amino acids. Determination of the relationship between unperturbed extracellular levels and the levels of amino acids in the collected fluids indicates that the concentrations of these amino acids were probably high enough to kill neurons for longer than one hour following impact injury to the spinal cord. Increases in the concentrations of the metabolically related non-neurotransmitters asparagine and glutamine were considerably smaller. The latter observations suggest that much of the increase in levels of the excitatory amino acids resulted from neuronal activity rather than from simple damage.

Amino Acids↗
PubMed1991

Interleukin-6 stimulates motility of vascular endothelium.

Interleukin-6 (IL-6) is a cytokine which regulates host response to injury. Various preparations of recombinant human IL-6 stimulated migration of bovine brain and bovine aortic endothelial cells, with maximal responses at 100-600 ng/ml. The migration response was inhibited by anti-IL-6 monoclonal antibody. IL-6 also inhibited endothelial cell proliferation in a dose-dependent fashion. Combinations of IL-6 and tumor necrosis factor induced additive stimulation of migration. Studies with inhibitors and stimulators of various metabolic processes suggest that IL-6-induced motility: 1) does not require a pertussis toxin-sensitive G-protein, protein kinase C, or DNA synthesis; and 2) is regulated differently from the motility induced by scatter factor. A possible role for IL-6 in the regulation of physiologic angiogenesis is discussed.

Animals↗
PubMed1991

Clearance of S-(3-amino-2-hydroxypropyl) phosphorothioate (WR-77913) in rats.

Complications of radiotherapy in the treatment of retinal and choroidal neoplastic diseases include cataract formation, radiation retinopathy, neovascular glaucoma, cystoid macular edema, and subretinal neovascularization. These side effects may be minimized by the use of compounds known to have a protective effect on normal ocular tissues without impeding the benefits of therapy. Phosphorothioates, first developed under the Antiradiation Drug Development Program of the U.S. Army Medical Research and Development Command, have been reported to protect normal tissues during radiation therapy in a variety of animal models. One of the phosphorothioates, WR-77913 (S-[3-amino-2-hydroxylpropyl]phosphorothioate) was found to inhibit cataract formation in rats after radiation exposure. To test the efficacy of WR-77913 in the retina, we established a high-pressure liquid chromatography method to measure the levels of dephosphorylated WR-77913 and studied the drug's clearance from the lens, retina, blood, kidney, and liver in rats.

Amifostine↗
PubMed1991

Insulin absorption is faster when keeping the infusion site in use for three days during continuous subcutaneous insulin infusion.

To evaluate the possible influence of regular infusion site changes on insulin absorption, fifteen type 1 diabetic patients using continuous subcutaneous insulin infusion (CSII) were studied on four occasions: the first day after an infusion site was settled, again the first day after a new infusion site was utilized and the two fourth days after the two infusion sites had been used for three days. A bolus of insulin (1 U/10 kg of body weight) was infused by the pump in the lower para-umbilical region. Plasma free insulin and blood glucose levels were determined before and during 240 min of the study at 30-min intervals. It was found that the peak times extracted from the individual insulin curves were shorter in 17 out of 23 curves when the fourth day was compared with the first day and the mean value of peak time of the fourth day was significantly shorter than that of the first day (56 +/- 11 vs 110 +/- 15 min, P less than 0.01). The mean area under the insulin curves during the first hour of the study tended to increase on the fourth day compared to that of the first day (25 +/- 2.2 vs 21 +/- 2.1 mU.l-1.min, P = 0.12). The decremental area of blood glucose on the fourth day was larger than on the first day (405 +/- 111 vs 82 +/- 160 mmol.l-1.min, P less than 0.05). We conclude that during CSII, the absorption rate of the injected insulin bolus is faster when the infusion site has been in use continuously for three days.

Absorption↗
PubMed1991

Hydatid disease in China.

Hydatid disease is one of the world's most geographically widespread zoonoses. It is present on all inhabited continents and occurs in tropical, subtropical, temperate, sub-arctic and arctic regions. The two countries with the greatest areas over which transmission occurs are almost certainly the Soviet Union and China. Until recently, however, very little information about hydatidosis in China was available outside the country(1). Since the 'open-door' policy over the past few years the great importance of hydatid disease in north and western China is gradually being realized.

Journal Article↗
PubMed1991

Insulin clearance during hypoglycemia in patients with insulin-dependent diabetes mellitus.

Eight male patients with insulin-dependent diabetes mellitus (IDDM) without residual beta-cell function were studied on two occasions in random order. In one experiment hypoglycemia was induced by a constant rate iv infusion of insulin (0.034 U/kg/h) during 150 minutes. At the other occasion an identical infusion of insulin was given, but this time euglycemia was maintained by a variable iv infusion of glucose. Plasma levels of free insulin were almost identical during the two experiments indicating that insulin clearance is not influenced by hypoglycemia in patients with IDDM.

Adult↗
PubMed1991

Gold weight lid load as a secondary procedure.

This paper discusses the use of gold weight lid load as a secondary procedure. By using three representative patients, I emphasize the following points: First, the dominance of the eye must be determined so that postoperative changes in the eyelid height can be anticipated. Second, in order to obtain an accurate weight of the implant needed, the restrictive effect on the eyelid from the previous surgery (a tarsorrhaphy or an encircling band) must first be eliminated. Third, to ensure the best result and the patient's comfort, lacrimal function, Bell's phenomenon, and levator function must be assessed.

Adult↗
PubMed1991

Relationships among the rfb regions of Salmonella serovars A, B, and D.

The O antigens of Salmonella serogroups A, B, and D differ structurally in their side chain sugar residues. The genes encoding O-antigen biosynthesis are clustered in the rfb operon. The gene rfbJ in strain LT2 (serovar typhimurium, group B) and the genes rfbS and rfbE in strain Ty2 (serovar typhi, group D) account for the known differences in the rfb gene clusters used for determination of group specificity. In this paper, we report the nucleotide sequence of 2.9 kb of DNA from the rfb gene cluster of strain Ty2 and the finding of two open reading frames which have limited similarity with the corresponding open reading frames of strain LT2. These two genes complete the sequence of the rfb region of group D strain Ty2 if we use strain LT2 sequence where restriction site data show it to be extremely similar to the strain Ty2 sequence. The restriction map of the rfb gene cluster in group A strain IMVS1316 (serovar paratyphi) is identical to that of the cluster in strain Ty2 except for a frameshift mutation in rfbE and a triplicated region. The rfb gene clusters of these three strains are compared, and the evolutionary origin of these genes is discussed.

Amino Acid Sequence↗
PubMed1991

A high concentration of circulating insulin suppresses the glucagon response to hypoglycemia in normal man.

In an attempt to clarify whether circulating insulin per se exerts an inhibitory effect on the hormonal responses to hypoglycemia, with special emphasis on glucagon secretion, nine healthy volunteers were exposed to low dose (244 pmol/kg.h) and high dose (1034 pmol/kg.h) iv insulin infusions for 3 h on two separate occasions. A close to identical arterial hypoglycemia of about 3.4 mmo/L was obtained in both tests by glucose clamping during the high dose test. The corresponding glucose concentration in the venous blood was significantly lower in the high dose test (2.5 +/- 0.1 vs. 3.0 +/- 0.1 mmol/L; P less than 0.01), while the plasma free insulin level was 4 times higher in the high dose test (897 +/- 50 vs. 208 +/- 14 pmol/L). Plasma glucagon was elevated in both experiments, but its rise was reduced during the high dose test after 1 h, yielding an incremental area under the glucagon curve that was significantly smaller than that obtained during the low dose test (213 +/- 70 vs. 348 +/- 81 ng/L.h; P less than 0.05). The plasma adrenaline, noradrenaline, GH, C-peptide, pancreatic polypeptide, and somatostatin profiles were similar in the two tests. We conclude that an inhibitory effect of circulating insulin on the glucagon response to hypoglycemia can be demonstrated in normal man during an infusion of insulin yielding a plasma concentration of about 900 pmol/L. The responses of other hormones studied are not significantly influenced by the circulating insulin level.

Adult↗
PubMed1991

Cough in hot pepper workers.

STUDY OBJECTIVE: To determine whether there is an effect on the prevalence of respiratory symptoms, an alteration in lung function, or an increase in the cough threshold to capsaicin among workers chronically exposed to hot chili (Capsicum) peppers. DESIGN: Cross-sectional study of responses to a structured questionnaire, lung function assessed by spirometry and cough threshold to inhalation of capsaicin aerosol in a group of occupationally-exposed Capsicum workers as compared to non-exposed employees of the same work site. SETTING: Spice manufacturing facility. PARTICIPANTS: Twenty-two Capsicum-exposed and 19 nonexposed workers. MEASUREMENTS AND MAIN RESULTS: When evaluated by questionnaire, 13 (59 percent) of the Capsicum-exposed workers reported cough as compared to 4 (21 percent) of the nonexposed workers (p less than 0.05). Baseline FEV1 and FVC did not differ between the two groups. Cough threshold, as assessed by the lowest concentration of inhaled capsaicin eliciting cough, was related to workplace exposure (p = 0.05), displaying a bimodal pattern of higher and lower cough thresholds among the Capsicum workers as compared to a unimodal distribution among the nonexposed workers. Within the exposed group, a higher cough threshold was significantly related to male gender (p = 0.03) and was associated to a lesser extent with dietary preference for hot food (p = 0.09) and cumulative cigarette smoking (p = 0.07). CONCLUSION: Chronic occupational exposure to chili peppers is associated with complaints of cough but does not alone lead to decreased responsiveness of capsaicin-sensitive nerves when assessed by cough threshold. The cough response to capsaicin inhalation may be modified by the effects of multiple, potentially interactive factors.

Adult↗
PubMed1991

[Pathological and X-ray study on bony specimens of rickets from 124 fetal and infantile autopsies].

The results of pathological and X-ray study on rickets of bony specimens from fetal and infantile autopsies are reported. Three important links were stressed in designing the study. The cases were divided into two groups: "congenital" and "postnatal". Each case has pathological slides and X-ray photographs of the rib, ulna and radius. GMA sections were used in this study to avoid decalcification and constriction of the bony specimens. The results showed that: Congenital rickets is existent in Beijing. Its incidence is 25.4%. The bony change was seen as early as 30 weeks of pregnancy. The pathological and X-ray features are not different between the "congenital" and "postnatal" groups; The incidence of fetal and infantile rickets is 35.5%. It is the highest in the rib, moderate in the ulna and lowest in the radius. The correlation of X-ray and pathological rickets was found to be 82.5% (rib), 77.3% (ulna) and 50% (radius). It can be seen that X-ray examination of the rib may raise the diagnostic rate to 12 times of that based on traditional wrist examination.

Fetus↗
PubMed1991

[Restriction fragment length differences of genomic repetitive DNA from five sibling species of Anopheles hyrcanus group].

Genomic DNA were prepared from 5 sibling species of Anopheles hyrcanus group including An. sinensis (ASS), An. anthropophagus (ALA), An. liangshanensis (ALS), An. crawfordi (ACW) and An. xiaokuanus (AXK). High molecular weight DNA from each species were cut with three restriction endonucleases (Bgl II, Hae III and Pst I) and the DNA fragments analysed by agarose gel electrophoresis and ethidium bromide staining. Three enzymes (Bgl II, Hae III and Pst I) produced unique fragments in all sibling species tested. A diagnostic restriction fragment length of DNA from 5 sibling species of An. hyrcanus group may be derived from a single restriction enzyme pattern (i.e. Bgl II). The results demonstrated that the restriction fragment length differences of repetitive DNA could used as a tool to distinguish sibling species of An. hyrcanus group.

Animals↗
PubMed1991

Release and metabolism of 5-hydroxytryptamine in the cat spinal cord examined with microdialysis.

The primary objective of this work was to investigate how in vivo administration of depolarizing agents increases extracellular concentrations of 5-hydroxytryptamine (5-HT) and simultaneously decreases levels of its chief metabolite 5-hydroxyindole-3-acetic acid (5-HIAA). To this end the effects of a number of agents on extracellular levels of 5-HT and 5-HIAA in cat spinal cord were determined by microdialysis and high-pressure liquid chromatography with electrochemical detection. The semipermeable portion of the dialysis probe was centered in the dorsal horn. Artificial cerebrospinal fluid containing elevated K+ or drugs was introduced into the dorsal horn via the dialysis probe. Increases in recovered 5-HT were assumed to reflect increased levels in the extracellular fluid due to release, reduced reuptake and/or reduced metabolism. Depolarizing agents (K+, veratridine and aconitine) increased 5-HT, but dramatically decreased 5-HIAA levels. Extracellular 5-HT returned to near base-line levels with removal of the depolarizing agents. The reduction in 5-HIAA was transient after potassium infusion, but outlasted the infusion of veratridine or aconitine by several hours. Reduction of 5-HIAA could be blocked or reversed with the Na+ channel blockers, lidocaine and tetrodotoxin. Evidently, the decrease in 5-HT metabolism followed activation of sodium channels. Parachloroamphetamine caused an increase in 5-HT levels, presumably reflecting increased 5-HT release, but did not change 5-HIAA levels. Although fluoxetine increased 5-HT, it reduced 5-HIAA, presumably through blockade of 5-HT reuptake leading to a secondary reduction in metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Aconitine↗
PubMed1991

Application of uniform design in L-isoleucine fermentation.

Uniform design was employed in our experiments for testing the effects of nine different compositions of the culture media for the production of L-isoleucine in Corynebacterium crenatum A11 fermentation. The most favorable medium was found to be composed of glucose 12%, (NH4)2SO4 2%, KH2PO4 0.1%, K2HPO4 0.45%, MgSO4.7H2O 0.055%, biotin 1 microgram, thiamine 20 micrograms, FeSO4.7H2O 2 ppm, MnSO4.4H2O 2 ppm, CaCO3 4% with pH 7.0-7.2. By using such medium, the amount of L-isoleucine produced by A11 was increased up to 15.1 mg/ml. Uniform design, as compared with orthogonal design, has the advantages of higher efficiency and easier analysis of the factors that affect the production.

Ammonium Sulfate↗
PubMed1991

[The significance of immunoblot in serodiagnosis of cysticercosis cellulosae].

50, 92 and 30 samples collected respectively from cases with cysticercosis cellulosae, other parasitic diseases and normal controls were examined with SDS-gradient (5-20%) polyacrylamide-gel electrophoresis and immunoblot. The results showed that 26 KD protein band of the cysticercus antigen is highly specific for cysticercosis and no cross reaction could be seen in patients with other parasitic diseases, especially hydatid disease, and healthy controls. As we know that the cysticercus antigen usually has a high cross-reaction rate with hydatidosis by ELISA method, the positive rate of this test for cysticercosis is 70% in comparison with 80% and 76% of ELISA and CFT respectively and the difference in the figures of these three tests has no statistical significance. Our study suggested that this method is valuable in clinical diagnosis and epidemiological surveys for research work on cysticercosis cellulosae.

Animals↗
PubMed1991

[Common antigenic components in soluble antigens shared by Schistosoma japonicum eggs and Paragonimus westermani adult worms].

Using enzyme-linked immunoblot technique (ELIB), the antigenic protein components of water-soluble and urea-soluble antigens of Schistosoma japonicum eggs (JSEA, JEAU) and Paragonimus westermani adult worms (PAA, PAA-U) were analysed. The results showed that in both JSEA and JEA-U, 8 and 3 bands of polypeptides could be recognized by sera from patients with schistosomiasis japonica (Sj). In both PAA and PAA-U, there were 9 and 2 bands of polypeptides respectively, which could be recognized by sera from patients with pagumogonimiasis skrjabini (Ps). The components of 36/37kDa in PAA and 20/21 kDa in JSEA were identified to be shared antigenic fractions existing between the two species of trematodes, which gave positive reaction against patient's sera from both S.j. and P.s., while PAA-U caused the reaction only with sera from patients with acute schistosomiasis. PAA-U might be useful to avoid cross reaction in the majority of schistosomiasis patients in the fields.

Animals↗