Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 757 records · Page 42Linked to original sources

PubMed1994

The superior effect of the combination of FK 506 and deoxyspergualin on rat cardiac allograft survival.

In this present study, the effects of FK 506 and 15-deoxyspergualin (DSG), with respect to dose, timing, and combination, were investigated in an ACI-to-LEW rat cardiac allograft model. FK 506 was administered intramuscularly for 14 days starting on day 0 after grafting, while DSG was given intraperitoneally for 7 days starting on day 0,4, or 7 after transplantation. FK 506 or DSG monotherapy prolonged cardiac allograft survival in dose-dependent manners, and the minimum effective dose for overcoming rejection was 0.1 mg/kg per day in the case of FK 506 and 1.0 mg/kg per day for DSG. The graft survival rate was higher with administration of DSG starting on day 4 on day 0 after transplantation. A low dosage of FK 506 starting on day 0, in combination with DSG starting on day 0 or day 4 (but not on day 7), had a synergistic effect in prolonging allograft survival for 14.0 +/- 3.3 days and 25.4 +/- 8.2 days, respectively. The most effective combination treatment schedule for prolongation of allograft survival was FK 506 starting on day 0 and DSG starting on day 4 after transplantation.

Animals↗

PubMed1994

Biliary excretion of exogenous cadmium and manganese in Long-Evans Cinnamon (LEC) rats characterized by an inherently gross amount of copper-metallothionein in the liver.

Long-Evans Cinnamon (LEC) rats are characterized by the sudden onset of hepatitis around 4 months after birth and the gross accumulation of hepatic copper (Cu) accompanied by metallothionein (MT). The biliary excretion of manganese (Mn) and cadmium (Cd) injected intravenously was studied in 3-month-old LEC rats without signs of hepatitis. Injected Mn was excreted into the bile in LEC and Fischer rats used for comparison. However, increased biliary excretion of Cd was found not in the LEC rat but in the Fischer rat. Excretion of horseradish peroxidase (HRP) injected along with the metal mixture was significantly lower in the LEC group than in the Fischer group. Our results suggest that Mn excretion is not related to the existence of a gross amount of Cu-MT. Reduced excretion of Cd may be partly due to binding to Cu-MT in the liver. Decreased excretion of HRP implies the existence of an inherent defect in the bile excretion route for endo- and exogenous substances.

Animals↗

PubMed1994

Antinociception without motor blockade after subarachnoid administration of S-(+)-ibuprofen in rats.

This study was designed to determine whether the nonsteroidal anti-inflammatory drug (NSAID) sodium S-(+)-ibuprofen (IB), can be used intrathecally as a substitute analgesic for opiates to avoid the side effects of intrathecal narcotics. One week or more after surgical implantation of subarachnoid catheters, four groups of Sprague-Dawley rats were given 0.05 ml subarachnoid injections containing one of the following: Group A, normal saline (NS); Group B, IB 0.25 mg, 0.5 mg and 1.5 mg; Group C, morphine (M) 0.05 mg and 0.025 mg; Group D received NS or IB 1.5 mg. Animals were sacrificed for spinal cord examination one week after injection. Tail flick response latency (TFL) was determined before and 15, 30, 60, 120 and 180 minutes after each injection. TFL differences were compared. IB 1.5 mg vs NS, IB 0.5 mg vs NS, IB 0.25 mg vs M 0.05 mg, IB 0.25 mg vs M 0.025 mg, M 0.05 mg vs NS, and M 0.025 vs NS showed p < 0.05. IB 1.5 mg vs M 0.05 mg and M 0.025 mg, IB 0.5 mg vs M 0.05 mg and M 0.025 mg revealed no significant difference. No motor impairment was observed in any animal. Light microscopy of the spinal cord revealed no evidence of pathological changes in any animal (group D).

Analysis of Variance↗

PubMed1994

Use of recombinant pp38 antigen of Marek's disease virus to identify serotype 1-specific antibodies in chicken sera by western blotting.

A fowlpox recombinant expressing the pp38 antigen of Marek's disease virus has been constructed. Production of pp38 in chick embryo fibroblasts (CEF) infected at a m.o.i. of 1 pfu/cell occurred over a period of 5 days and reached a peak at 72 h after infection. The pp38 antigen could be released from infected cells by freezing and thawing. Western blot analysis showed that denatured pp38 antigen reacted with antisera from chickens inoculated with serotype 1 MDV but failed to react with antisera from chickens inoculated with MDV serotype 2 or HVT. The results suggest that MDV pp38 contains a serotype 1-specific epitope which becomes available upon denaturation of the antigen and that this could be exploited to identify MDV-specific antibodies in epidemiological studies. The relationship between pp38 and the related polypeptides pp24 and pp41 in MDV-infected cells was also examined. The results suggest that pp24 and pp38 are synthesised independently and that MDV coded proteins (probably a protein kinase) might be required to convert pp38 to pp41.

Animals↗

PubMed1994

Antigenic and molecular characterization of hantavirus isolates from China.

Hemorrhagic fever with renal syndrome (HFRS) is caused by certain viruses in the genus Hantavirus, family Bunyaviridae, and is a major public health problem in China. By using molecular and serological tests, we characterized 15 hantaviruses isolated either from patients with HFRS or from rodents captured in endemic areas of China. By cross plaque-reduction neutralization tests performed with rabbit immune sera, we identified two serologically distinct groups of viruses, comprised of those related to Hantaan virus, and those related to Seoul virus. To study the genetic relationships among these viruses, we amplified a 330 base pair region of the medium (M) genome segment of each isolate by reverse transcription and polymerase chain reaction (PCR) and compared the nucleotide sequences to those of other, well-characterized hantaviruses. In addition, we PCR-amplified and analyzed the entire coding region of the small (S) genome segment of each isolate by restriction enzyme digestion with a battery of enzymes. The results of our genetic analyses of both the M and S segments of these isolates confirmed our serological data, indicating that Hantaan and Seoul viruses co-circulate in endemic disease regions of China. We constructed a phylogenetic tree based on multiple alignment of the partial M segment sequences. The resulting dendrogram distinguished three genetic subtypes of Hantaan viruses and one type of Seoul virus.

Animals↗

PubMed1994

Mechanism of light modulation: identification of potential redox-sensitive cysteines distal to catalytic site in light-activated chloroplast enzymes.

Light-dependent reduction of target disulfides on certain chloroplast enzymes results in a change in activity. We have modeled the tertiary structure of four of these enzymes, namely NADP-linked glyceraldehyde-3-P dehydrogenase, NADP-linked malate dehydrogenase, sedoheptulose bisphosphatase, and fructose bisphosphatase. Models are based on x-ray crystal structures from non-plant species. Each of these enzymes consists of two domains connected by a hinge. Modeling suggests that oxidation of two crucial cysteines to cystine would restrict motion around the hinge in the two dehydrogenases and influence the conformation of the active site. The cysteine residues in the two phosphatases are located in a region known to be sensitive to allosteric modifiers and to be involved in mediating structural changes in mammalian and microbial fructose bisphosphatases. Apparently, the same region is involved in covalent modification of phosphatase activity in the chloroplast.

Amino Acid Sequence↗

PubMed1994

Structure elucidation of three triterpenoid saponins from Alphitonia zizyphoides using 2D NMR techniques.

High-field nmr experiments have been used to determine the structures of three new saponins, zizyphoisides C, D, and E [1-3], isolated from Alphitonia zizyphoides, a medicinal plant found in the Samoan rain forest. The saponins consist of the aglycone, jujubogenin, to which are attached three sugar units and an unsaturated side-chain. The three compounds are similar except for the location of an acetyl group on one of the sugar units.

Carbohydrate Sequence↗

PubMed1994

Injecting drug use and HIV infection in southwest China.

OBJECTIVES: To determine the prevalence of drug injection among drug users, the seroprevalence of HIV and risk factors for HIV infection among injecting drug users (IDU), and to determine heterosexual transmission of HIV among IDU and their spouses in southwest China. METHODS: Using a cross-sectional design, we conducted an HIV seroprevalence and behavioral survey in three rural counties of Yunnan province, Ruili, Longchuan and Luxi in southwest China, bordering Myanmar (Burma). A total of 860 drug users were recruited in randomly selected communities at the three study sites (response rate, 97%). In addition, a random sample of 62 wives of HIV-infected IDU were assembled from 460 known HIV-positive IDU in Ruili and Longchuan (response rate, 81%). RESULTS: In the sample of 860 drug users, 33% reported injecting drugs. Among the 282 subjects who injected drugs, 82% began intravenous drug use after 1988; 64% injected drugs at least once every day. All subjects shared needles but none cleaned the injection equipment with alcohol or bleach. Overall, 49% tested HIV-positive. HIV seropositivity was independently correlated with a longer history of drug injecting, daily injecting, frequent needle-sharing, being younger, and living in Ruili county. Among the 62 wives of HIV-positive IDU, none used condoms during sex and 10% tested HIV-positive. CONCLUSIONS: We conclude that the introduction of HIV into drug-using communities and the rapid increase in heroin injecting in this population appear to have triggered an explosive HIV epidemic among IDU in southwest China. We recommend that AIDS prevention efforts should begin immediately and focus on discouraging the shift from opium smoking to heroin injecting, needle-sharing, and unprotected sex among drug users and their partners.

Adult↗

PubMed1994