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Biomedical subjects

M Li

Publications and source records attributed to M Li.

At least 919 records · Page 51Linked to original sources
PubMed1995

[Urinary calcium excretion in patients with pregnant hypertension syndrome].

We observed the urinary calcium in 103 patients in the third trimester of pregnancy and the relation between the 24 hour calcium excretion and the calcium/creatinine ratio of a single void urine sample. The study population included 75 normal pregnant women and 28 pregnant woman with pregnant hypertension syndrome. The 24 hour urinary calcium excretion in the patients with pregnant hypertension syndrome was significantly lower (0.70 +/- 0.36 mmol/L) than that in normal pregnant women (4.00 +/- 1.90 mml/L) P < 0.0005. The 24 hour calcium excretion correlated well with the calcium to creatinine ratio of a single void morning urine sample in the two groups. We conclude that the urinary calcium excretion can be used as an indicator for pregnant hypertension syndrome. The 24 hour urinary calcium excretion can be estimated from a single void urine sample. Pregnant hypertension syndrome is associated with hypocalciuria, probably due to increased tubular reabsorption of calcium.

Adult↗
PubMed1995

Pharmacokinetics of chimeric L6 conjugated to indium-111- and yttrium-90-DOTA-peptide in tumor-bearing mice.

UNLABELLED: A bifunctional chelating agent, DOTA-Gly3-L-(p-isothiocyanato)-phenylalanine amide (DOTA-peptide-NCS), was studied in nude mice bearing human breast cancer xenographs (HBT 3477) to determine its potential for radioimmunoconjugate therapy. METHODS: Indium-111 and yttrium-90 were attached to an anti-adenocarcinoma chimeric L6 (ChL6) monoclonal antibody (MAb) after pre-chelation to the DOTA-peptide-NCS and the desired neutral radiochelates were obtained by purification. The unique characteristic of the DOTA-peptide-NCS to form neutral complexes with trivalent metals was utilized to separate the resulting 111In and 90Y radiochelates from excess chelating agent and other anionic by-products resulting from metal impurities. The purified radiochelates were then conjugated to ChL6. The pharmacokinetics of 111In- and 90Y-DOTA-peptide-ChL6 were obtained for 5 days after injection in nude mice bearing HBT 3477 xenographs. The results were compared with the pharmacokinetics of 125I-ChL6 obtained in the same mouse model. RESULTS: The whole-body clearance of 125I-ChL6, 90Y- and 111In-DOTA-peptide-ChL6 was monoexponential with biologic half-times of 92, 104 and 160 hr, respectively. Blood clearances of the three radiopharmaceuticals were biphasic. The radiometal immunoconjugates had greater tumor uptake and slower clearances. CONCLUSION: Indium-111- and 90Y-DOTA-peptide-ChL6 can be produced at high specific activity with fewer than one chelate per MAb by using a pre-labeling method that permits radiochelate purification by charge selection. Studies in mouse xenografts indicate that tumor uptake is enhanced and a favorable therapeutic index is achieved using these agents.

Animals↗
PubMed1995

Mechanism of cytosine arabinoside toxicity to the blast cells of acute myeloblastic leukemia: involvement of free radicals.

Retinoic acid and hydrocortisone (HC) have been shown to regulate the drug sensitivity of the blast cells of acute myeloblastic leukemia (AML). We asked if the proto-oncogene bcl-2 played a role in this regulation. As target cells we used the continuous lines, OCI/AML-1, OCI/AML-2 or OCI/AML-5; expression of bcl-2 can be detected by Northern analysis of RNA from OCI/AML-2 or OCI/AML-5 cells; bcl-2 expression can be found in OCI/AML-1 cells only by using RT-PCR. Exposure of OCI/AML-2 or OCI/AML-5 cells to retinoic acid (all-trans retinoic acid, ATRA) led to a down-regulation of bcl-2 expression that was first seen after 2 h of exposure and was complete after a day. The down-regulation could be prevented by exposing the cells to ara-C either before or after ATRA; decrease in bcl-2 protein was moderate and only obvious after 36 h of ATRA treatment. Nuclear run-on experiments provided evidence that bcl-2 down-regulation was occurring at transcriptional and post-translational levels. Since bcl-2 is considered to have anti-oxidant activity, we tested the sensitivity of the three cell lines to H2O2; we found that OCI/AML-1, the line with very low bcl-2 expression, was a 100-fold more H2O2-sensitive than OCI/AML-2 or OCI/AML-5, where bcl-2 expression can be detected readily. We then asked if H2O2 sensitivity could be regulated. We found that exposure of cells to HC before H2O2 was protective while ATRA after peroxide treatment increased killing; this is the same pattern of regulation observed when AML blasts are exposed to HC before, or ATRA after ara-C. Finally, we asked whether N-acetylcysteine (NAC), a known radical scavenger would protect cells against ara-C killing. Significant protection was observed when NAC was given before drug, but not if given after drug. NAC protection against ara-C killing was seen for OCI/AML-1 and 2 cells, but not for OCI/AML-5 cells. We interpret the results as follows: ara-C kills cells in two ways: first, directly, by incorporation into DNA and chain termination; second, indirectly, by inducing the production of toxic radicals. Bcl-2 reduces the oxidant activity of such radicals, and is protective. ATRA regulates ara-C toxicity by its action on bcl-2. Left unexplained are the action of HC, which does not affect bcl-2 expression and the mechanism by which ara-C prevents down-regulation of bcl-2 by ATRA.

Acetylcysteine↗
PubMed1995

Diarrhoea in piglets and monkeys experimentally infected with Balantidium coli isolated from human faeces.

Ten piglets and four monkeys free from Balantidium were dosed with human faecal homogenate which contained 1.2 x 10(4)-4.8 x 10(4) B. coli cysts. The infection resulted in severe diarrhoea in piglets 1-6 and hydrocortisone-treated monkeys 1-2, moderate diarrhoea in piglets 7-10 and a subclinical infection in monkeys 3-4. In piglets 1-3 and monkeys 1-2, heavy infection of the intestinal mucosa extended from the terminal ileum to the rectum and the mucosa was severely damaged. In piglets 4-10, infection was heavy in the large intestine with moderate mucosal damage.

Animals↗
PubMed1995

Interaction of flavones and their bromoacetyl derivatives with NAD(P)H:quinone acceptor oxidoreductase.

Flavones are a new type of inhibitor of NAD(P)H:quinone acceptor oxidoreductase (DT-diaphorase, EC 1.6.99.2). To further characterize the flavone binding site, three bromoacetyl derivatives of flavones, i.e., 7-bromoacetylflavone, 5-hydroxyl-7-bromoacetylflavone, and 7,8-dibromoacetylflavone, have been synthesized. These compounds have been found to be potent inhibitors that inactivate the rat quinone reductase in a time-dependent manner, suggesting that they can be used as affinity labels for the enzyme. Among the three bromoacetyl derivatives, 7,8-dibromoacetylflavone is the most potent inhibitor; however, its labeling of the quinone reductase is the least stable, so that the enzyme regains activity after a short incubation. In contrast, the inactivation of the quinone reductase by 5-hydroxyl-7-bromoacetylflavone is stable. Accordingly, this flavone derivative is the most suitable compound for labeling the flavone binding site of the enzyme. Electrospray mass spectrometry has been applied to demonstrate that 5-hydroxyl-7-bromoacetylflavone labels this enzyme in a stoichiometric manner.

Animals↗
PubMed1995

Anti-mesangial and anti-endothelial cell antibodies in IgA mesangial nephropathy.

In the present study we verified by solid phase ELISA the presence of antibodies against mesangial and endothelial cell constituents in patients with IgA-GN and Schoenlein-Henoch syndrome (SH). An antigen extract was prepared by sonication of human mesangial cell (MC) monolayers between third and fifth subculture and coated at 20 micrograms/ml on microtiter plates where sera were tested by incubation for 2 h at 37 degrees C and addition of peroxidase-conjugated anti-human IgG or IgA. In comparison to 86 normal controls, increased levels of IgG anti-MC antibodies were found in 15/84 patients with IgA-GN and 4/11 with SH. IgA antibodies were always negative. Furthermore anti-endothelial cell antibodies (AECA) were sought in the same patients and controls by ELISA as previously described. Increased levels of IgG and IgA AECA were found in 25/62 and 24/46 patients respectively. A cross-inhibition test showed that preadsorbment of positive sera for both IgG anti-MC and IgG AECA on endothelial cells in culture resulted in an inhibited binding of IgG to MC. HPLC-ELISA and Western blot analysis of the MC extract showed a significant binding of IgG from ELISA-positive sera to a protein band of 25-50 kD. Similar results were obtained by Western blot analysis of an endothelial cell extract. These results suggest the identity of the antigens recognized by IgG antibodies on endothelial cells and MC in patients with IgA-GN.

Adolescent↗
PubMed1995

[Dumbbell like neurinoma at upper cervical vertebra: report of 48 cases].

48 dumbbell like neurinoma at upper cervical vertebra were totally removed operatively and confirmed pathologically. Intermittent pain at neck and occiput limitation of neck movement, and numbness or pain at one or both side limbs were the most common symptoms. In the early stage, the disease was difficalt to recognize. If X-ray film of the cervical vertebra at bioblique position showed an enlarged intervertebral foramen, the diagnosis of neurinoma should be highly considered. MRI could make a definite diagnosis. Vertebral artery angiography is of great value. We also introduced experience in how to protect vertebral artery and respiratory function during operation.

Adolescent↗
PubMed1995

[Effects of intrasubarachnoid space injection of anti dynorphin A1-13 serum or nor-BNI on the recovery of spinal cord injury in rats].

A pronounced and reversible spinal cord compression injury was performed by the compression of a metal plate 2.2mm x 5. Omm in size to the exposed spinal dura and loaded with 35g weight for 5 minutes at T7-8. Anti dynorphin serum at 10 microliters (1:30000) or kappa antagonist nor-BNI at 100 ng was administered intrasubarachnoidly shortly after the injury, with half dose applied 1, 2, 3 h after the injury for another three times. The recovery of neurological function was investigated. The results showed that the recovery of the muscle tension and motor function of the hindlimb in anti dynorphin serum group is markedly faster than that in both control and nor-BNI groups. Also the recovery of motor function in nor-BNI group is favourable at the earlier stage of injury, comparing to the control group. There were no significant differences in the change of mean arterial pressure and blood physiological parameters among the three groups.

Animals↗
PubMed1995

[Chemical constituents of Stellera chamaejasme L].

Twelve compounds were isolated from the roots of Stellera chamaejasma. Five of them were elucidated by spectroscopic and chemical methods as 3', 14-dimethyl-4', 11-dimethoxy-5, 7-dihydroxybenzoflavanone (10), daphnetin (1), umbelliferone (2), daucosterol (5) and beta-sitosterol (3). Compound 10 is new. Compounds 1, 2, 5, 10 were isolated for the first time from S. chamaejasme.

Benzoflavones↗
PubMed1995

[Ginkgolides antagonizing some effects of platelet-activating factor in vitro].

The mixture of platelet-activating factor (PAF) and platelets produced significant contraction of guinea pigs' bronchus, while the contraction induced by PAF alone was mild relatively, the IC50 were 6.14 x 10(-7) mol/L and 6.32 x 10(-4) mol/L respectively. There was significant difference between these two groups (P < 0.05). When the platelets were pre-incubated with ginkgolides for 10 minutes in Tris-Tyrode's buffered saline, effects of the PAF and platelets mixture were significantly inhibited (P < 0.01). Exposure of guinea pigs' bronchus to PAF in vitro resulted in a loss of beta-adrenergic receptors and responses to isoproterenol, and this effect of PAF was prevented by prior incubation of the guinea pigs' bronchus with ginkgolides (P < 0.05). The results showed ginkgolides were a potent PAF antagonist.

Animals↗
PubMed1995

[Peripheral anterior synechiae overlying the haptics of posterior chamber lenses].

To study the changes of the anterior chamber angle after intraocular lens implantation, 111 patients (130 eyes) with posterior chamber intraocular lens implantation at different post-operative periods were examined by gonioscopy. Peripheral anterior synechia overlying the position of the lens haptic (lens haptic PAS) was observed in up to 50.8% of eyes implanted with haptics vaulted anteriorly by 10%. The lens haptic PAS is easy to be identified, it is a broad based forward displacement of the peripheral iris adhesive to the anterior wall of the anterior chamber angle. The size of the PAS was of half to one o'clock position and occasionally it was of one and a half to two o'clock position. The differences between the rates of occurrence of lens haptic PAS were not significant at different post-operative periods (P > 0.05). 55.9% of the sulcus fixated and 42.3% of the capsular fixated eyes had lens haptic PAS (P > 0.05). There were more lens haptic PAS in eyes with horizontally oriented lens haptics (62.7%) than with lens haptics at vertical position (41.4%, P < 0.05). Regular gonioscopy for posterior chamber lens implantation was recommended.

Adult↗
PubMed1995

[The sandwich enzyme-linked immunoabsorbent assay of serum transferrin receptor by using monoclonal and polyclonal antibodies].

The human placenta transferrin receptor was purified in the form of transferrin-transferrin receptor complex (Tf-TfR), and a monospecific polyclonal antibody against TfR was developed by a Tf-coupled Sepharose 4B affinity chromatography to remove the anti-Tf components in the antiserum. A sandwich enzyme-linked immunoabsorbent assay (ELISA) was established for measuring serum transferrin receptor (sTfR) by using monoclonal antibody OKT9 and monospecific polyclonal antibody. This method is simple, specific and sensitive and has a good accuracy. The measurement of sTfR showed that the level of normal children was 4.54 +/- 1.08 mg/L. There were increased levels of sTfR in patients with severe iron deficiency anemia and those with hemolytic anemia (13.92 +/- 4.45 mg/L and 9.94 +/- 3.22 mg/L, respectively). In patients with aplastic anemia, the level was decreased (2.06 +/- 0.82 mg/L). These results indicate that the sTfR measurement has a differential significance for diagnoses of various anemia.

Anemia, Aplastic↗
PubMed1995

A study on the structure of human optic nerve lamina cribrosa.

PURPOSE: To determine the mechanism of nerve fiber damage in glaucoma by studying the structure of human optic nerve lamina cribrosa (LC) in different regions. METHODS: 15 human eyes of 10 cases were studied. The specimens were prepared for scanning electron microscopy, and numbers and areas of pores in LC were measured by electron image analysis system. Draw a frequency distribution map with each curve represents the tendency of pores distribution in a particular part. The proportion of the connective tissue in respective quadrant can also be calculated. The specimens were also prepared for histological examination. RESULTS: There are many pores of various magnitude and shapes on the surface of LC. There are significantly more large pores (> or = 3000 micron2) in the superior and inferior than those in the nasal and temporal quadrants, especially in the peripheral regions. In terms of area, the percentages of connective tissue in the nasal and temporal quadrants are the highest. Collageous fibers, various in diameter, are arranged in bundles and tangentially around each pore. CONCLUSION: In normal persons, the percentage of large pores in the superior and inferior peripheral parts is the highest, the density of the connective tissue is the lowest. So, the force received by unit area of the superior and inferior parts is bigger than that of the nasal and temporal sides, therefore, it is susceptible to the impact of high intraocular pressure at the early stage and causing corresponding visual defect. Our study may suggest the mechanism of optic nerve damage of glaucoma.

Adult↗
PubMed1995

[Effect of antiserum against dynorphin A administered intrathecally on spinal cord injury (SCI) of rats and its significance].

The antagonistic effects of antisera against dynorphin A, beta-endorphin, and leu-enkephailin administered intrathecally on secondary SCI were observed and compared after moderate SCI using principle of antigen-antibody neutralization reaction. The protective effect of antiserum against dynorphin A was most prominent on secondary SCI and the effect was more prominent when administered at 24 hours following SCI than when administered at 0 hour four hours, one week or two weeks following SCI. That suggests increase of dynorphin A level in spinal cord tissue may play an active role in the early stage, but its harmful effect on secondary SCI will be more and more prominent after accumulation of excessive dynorphin A.

Animals↗