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Biomedical subjects

J J Liu

Publications and source records attributed to J J Liu.

At least 109 records · Page 6Linked to original sources
PubMed1989

Ischaemia causes externalization of endothelin-1 binding sites in rat cardiac membranes.

Specific, high affinity binding sites for iodinated endothelin-1 ([125I]-ET-1) were identified in crude plasma and light membrane fractions harvested from aerobically perfused and ischaemic rat hearts, to determine whether the ischaemia-induced increase in binding site density (Bmax) involves externalization of the sites. In crude plasma membranes Bmax increased after 60 min ischaemia, from 113.5 +/- 2.15 to 180.6 +/- 4.67 fmol/mg protein (p less than 0.01). In the light membranes, the Bmax fell, from 94.7 +/- 8.70 to 63.80 +/- 6.26 fmol/mg protein (p less than 0.05). Hill coefficients and selectivity of both membrane fractions were unchanged. These results are interpreted as meaning that ischaemia causes externalization of cardiac [125I]-ET-1 binding sites.

Aerobiosis↗
PubMed1989

Mechanisms of resistance/susceptibility to murine encephalitozoonosis.

Mechanisms of resistance/susceptibility to the obligate intracellular protozoan Encephalitozoon cuniculi were studied in resistant BALB/c and susceptible C57BL/6 mice. Three immunological functions were examined: the production of lymphokine(s) (LK) by T-lymphocytes, the proliferative response of spleen cells to parasite spore fragments, and the ability of splenic and thioglycollate-induced peritoneal macrophages to act as accessory cells in antigen-induced T-cell proliferation. The two strains showed differences in the time required for LK production in vitro but not in their ability to generate LK. Spore fragment-induced lymphoblastogenesis was found in spleen cells of infected BALB/c and C57BL/6 mice. There was no difference between the two strains in dose response and time of maximal response, but the magnitude of maximal response was significantly less in C57BL/6 mice. Indomethacin was found to augment the lymphoproliferative response of C57BL/6 but not BALB/c mice, suggesting that prostaglandin production may be involved in immunosuppression in C57BL/6 mice. C57BL/6 mice required more splenic adherent cells to achieve the same proliferative response as found in BALB/c mice. The ability of thioglycollate-induced peritoneal macrophages to act as accessory cells in antigen-induced T-cell proliferation was less in C57BL/6 mice than in BALB/c mice. Thus, it appeared that the relative susceptibility of C57BL/6 mice to encephalitozoonosis may be due to defective accessory cell function of splenic and peritoneal macrophages, depressed lymphoproliferation against spore fragments (possibly due to prostaglandin-mediated suppression) and a delay in LK production. There was no significant difference between the survival times of BALB/c-nu and C57BL/6-nu mice, suggesting that non-immune mediated resistance did not play a role in determining resistance/susceptibility.

Animals↗
PubMed1989

The failure of endothelin to displace bound, radioactively-labelled, calcium antagonists (PN 200/110, D888 and diltiazem).

The effect of endothelin, a potent vasoconstrictor polypeptide, on three types of calcium antagonist binding sites was examined, in rat cardiac membrane fragments. Endothelin 10 nM affected neither the affinity nor density of dihydropyridine binding sites. At concentrations of 10(-12)-10(-7) M, endothelin failed to displace bound (+)-[3H]-PN 200/110, (-)-[3H]-D888 and (+)-cis-[3H]-diltiazem. These results suggest that the calcium antagonist binding sites associated with L-type calcium channels are not the primary site of action of endothelin.

Animals↗
PubMed1989

Streptozotocin-induced diabetes reduces the density of [125I]-endothelin-binding sites in rat cardiac membranes.

The effect of acute, streptozotocin-induced diabetes on the affinity (KD), density (Bmax) and selectivity of specific, high affinity binding sites for [125I]-endothelin [( 125I]-ET) in rat cardiac membrane fragments was determined. Three days after a single i.v. bolus dose of streptozotocin (60 mg kg-1), the density of [125I]ET binding sites was reduced (P less than 0.01) without changes in affinity or selectivity.

Animals↗
PubMed1989

[Extraction of effective parts of Alternanthera philoxeroides (Mart.) Griseb. and its antiviral effect].

Several parts of Alternanthera philoxeroides were extracted by lead-salt sedimentation and double phase solvent extractive technique and their antiviral effects were studied. The results showed that extracts of petroleum ether, ether, and ethyl acetate have inhibitory effect on epidemic hemorrhagic fever virus (EHFV). The antiviral effective part is coumarin analogue.

Antiviral Agents↗
PubMed1989

[Percutaneous transhepatic and transileocolic obliteration with absolute ethanol for the treatment of bleeding gastroesophageal varices].

Embolization of bleeding gastroesophageal varices with absolute ethanol performed in the recent two years was reported. The treatment was carried out either by means of percutaneous transhepatic or transileocolic obliteration. Obliteration treatment was attempted in 42 cases, among which 20 were transhepatic and 22 transileocolic. 16 of the 20 and 17 of the 22 were effectively obliterated with a total success rate of 78.6%. Two control groups of bleeding varices, one of 45 cases treated with conventional medical methods and the other of 53 cases treated with endoscopic sclerotherapy, were studied to compare the results. The efficacy for control of active bleeding in the obliteration, conventional and sclerotherapy groups were 100%, 84.1%, and 91% respectively, while the rebleeding rate was 27.2%, 31.5% and 23.2% and mortality rate (due to rebleeding) 12.1%, 31.5% and 11.6% respectively. The control of active bleeding, the results in the three groups were more or less similar, but the rebleeding rate was much lower in the obliteration and sclerotherapy groups than in the conventional group. However, sclerotherapy requires longer time and yields more complications than obliteration is a valuable therapeutic measure in controlling variceal bleeding and preventing rebleeding.

Embolization, Therapeutic↗
PubMed1989

[A preliminary study on mechanism of respiratory deficiency of mutagenesis in S. cerevisiae].

The results of ethidium bromide treatment for two different strains of S. cerevisiae were reported here. The recovery of respiratory competence was discovered when cells were treated with EB under non-growing condition. However, this recovery can be inhibited by caffeine. It was not observed when cells were treated with EB under growing condition. Similar results were obtained when cells were treated with EB during their exposure to KCN. The formation of at least one intermediate state [rho-] was proposed. The process of formation of respiratory deficiency could be expressed by rho+ in equilibrium [rho-]----rho-. The different concentrations of sucrose supplemented to the culture of S. cerevisiae resulted in certain influence in the experiment.

Ethidium↗
PubMed1989

[Laryngeal tuberculosis simulating epiglottitis--a case report].

Adult epiglottitis is an otolaryngological emergency. Under proper antibiotic therapy, however, most cases recover rapidly. This is a report of a case in which clinical findings indicated acute epiglottitis, but which showed no improvement with antibiotic therapy when treated by a local medical doctor for three weeks. Following the immediate application of a fiberoptic and microscopic direct laryngoscope with biopsy, an accurate diagnosis was established, i.e. laryngeal tuberculosis. After receiving the appropriate antituberculous therapy for just one week, the patient's symptoms improved dramatically.

Acute Disease↗
PubMed1988

Effect of urea, glycerol, and mannitol on basilar and labyrinthine arteries.

We studied the effect of urea, glycerol, and mannitol on basilar and labyrinthine arteries of dogs in vitro by use of tension recording methods. When the tissue was exposed to urea or glycerol, temporary relaxation of smooth muscles was initially observed, but was followed by gradually increasing contraction. With mannitol, relaxation of the smooth muscles remained stable as long as mannitol existed in the bathing solution. When the specimens were washed with normal Krebs solution after exposure to any of these three substances, large phasic contractions of the smooth muscles were observed. While only theoretical, we propose a possible explanation for the different effects of these three drugs in the improvement of hearing loss that results from Meniere's disease.

Animals↗
PubMed1988

Murine encephalitozoonosis: the effect of age and mode of transmission on occurrence of infection.

Experiments were conducted to determine whether neonatal mice are more susceptible to E. cuniculi than adult mice, and whether vertical and/or horizontal transmission occur in murine encephalitozoonosis. E. cuniculi infection in neonates did not cause mortality or clinical signs, but did result in chronic infection. Despite initial age-related immunodeficiency, mice infected as neonates eventually developed humoral and cell-mediated immune responses against the parasite comparable to those seen in adult mice. The results suggested that neonatal mice are not more susceptible to E. cuniculi than adult mice. Pups from either infected or normal parents did not differ in humoral and cell-mediated immune responses after challenge, suggesting that pups from infected parents were not infected with E. cuniculi during gestation. In contrast, mice became infected by caging with infected mice demonstrating that horizontal infection does occur.

Age Factors↗
PubMed1988

Dot enzyme-linked immunosorbent assay (dot ELISA) for antibodies to Encephalitozoon cuniculi.

A dot-ELISA procedure was developed to detect antibodies against Encephalitozoon cuniculi. Sera from 84 rabbits, 22 dogs, 18 squirrel monkeys and 200 mice were tested by dot-ELISA and most also were tested by immunofluorescence. Comparison of the two tests showed that there was excellent agreement of the results (Kappa values greater than or equal to 0.74) in all four species. Dot-ELISA is a simple, quantitative, rapid alternative to immunofluorescence when large numbers of serum samples must be evaluated.

Animals↗
PubMed1988

Encephalitozoon cuniculi infection in MRL/MPJ-LPR (lymphoproliferation) mice.

Experiments were conducted to determine (a) whether mice bearing the single autosomal recessive gene lpr (lymphoproliferation) are more susceptible to encephalitozoonosis than syngeneic mice without the lpr gene and (b) whether infection with Encephalitozoon cuniculi in autoimmune MRL/MPJ mice accelerates and/or exacerbates the development of hypergammaglobulinemia, a manifestation of encephalitozoonosis in dogs and foxes. The results suggested that the lpr gene does not influence susceptibility to murine encephalitozoonosis. Infection with E. cuniculi changed neither the onset nor the severity of the spontaneous, age-related hypergammaglobulinemia in MRL/MPJ mice. Hypergammaglobulinemic lpr mice with encephalitozoonosis did not develop more severe lesions than lpr mice without encephalitozoonosis nor was their death accelerated.

Animals↗
PubMed1987

Three correlations between extracellular calcium concentration and myocardial cell injury induced by drugs.

Primary cultures of newborn rat myocardial cells were treated in various extracellular calcium concentrations (0, 1.35, 2.7, 4.05, and 5.4 mM) with three different drugs; namely, ouabain, sulmazole, and chlorpromazine. Lactate dehydrogenase (LDH) release was used as an indicator of damage. The results showed 10(-3) M ouabain caused apparent damage of the cells and the damage was increased by an increased extracellular calcium concentration. Sulmazole (10(-3)M) caused damage of the cells in the absence of calcium; but it did not cause damage of the cells in the presence of calcium; it protected the cells from damage caused by high calcium concentrations (4.05 and 5.4 mM). Chlorpromazine (1.6 X 10(-4)M) caused severe damage of the cells. The various calcium concentrations had no influence on the degree of the damage. Correlation coefficients showed that correlations between the calcium concentrations and the cell damage caused by ouabain, sulmazole and chlorpromazine were positive correlation, negative correlation, and no correlation, respectively. It is suggested that influx of extracellular calcium is not a final common pathway of drug-induced myocardial cell injury, although it plays an important role in cell injury.

Animals↗
PubMed1987

Lysine-mediated tissue osmication in combination with a tannin-osmium conductive staining method for non-coated scanning electron microscopy of biological specimens.

Glutaraldehyde fixed rat kidney blocks showed no charging effect when treated with lysine and osmic acid and viewed in a scanning electron microscope using an acceleration voltage of 5-30 kV and a specimen current of 1 X 10(-10) A. The podocyte processes and endothelial micropores of the glomerulus were visible without metal coating. Glutaraldehyde fixed, tannin-osmium impregnated and lysine-osmium treated specimens also showed no charging effect in the scanning electron microscope, yielding instead much clearer scanning images which were comparable to those obtained from gold-coated specimens or from tannin-osmium-thiocarbohydrazide-osmium impregnated specimens (Murakami and Jones, 1980).

Animals↗
PubMed1984

Effects of long-term treatment of mice with anti-I-J monoclonal antibody and dialyzable leukocyte extract on immune function and lifespan.

In 1969 Walford hypothesized that age-related dysfunctions of the immune system may be involved in the pathogenesis of the lesions and disease of aging. Studies were initiated to test whether immunologic interventions intended to maintain the integrity of the immune system would delay the onset of diseases of aging and prolong lifespan. Adult BC3F1 mice were treated with anti-I-J monoclonal antibody, with human dialyzable leukocyte extract, or with saline once a week for one year. Spleen cells from the mice were then assayed for suppressor, T-helper and B-cell activity. Treatment with dialyzable leukocyte extract decreased the elevated nonspecific suppressor activity. Mice treated with anti-I-J antibody had elevated T-helper cell activity. In another experiment, mice were treated weekly with anti-I-J antibody, dialyzable leukocyte extract, or saline from 18 months of age until natural death. The mice were immunized with avian gammaglobulin at 27 and again at 29 months of age. Both types of immunologic intervention resulted in a greater secondary antibody response than that of the saline-treated control mice. Mice treated with anti-I-J antibody survived longer than did mice of the other two groups. There was a correlation between the magnitude of the secondary response of individual mice and their lifespan. The results provide support for the immunologic theory of aging.

Aging↗