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Biomedical subjects

R Li

Publications and source records attributed to R Li.

At least 505 records · Page 28Linked to original sources
PubMed1993

Management of major arterial injuries of the limbs in 166 cases.

The charts of 166 patients with major arterial injuries (175 arterial repairs) inflicted during periods of peace and war time were reviewed. One hundred and sixty-seven (95%) of the arteries repaired remained patent. Nine patients had limbs which developed ischemic contracture. Nine patients required amputations. Follow-up data was obtained from seventy-five patients with an average follow-up of five years and one month (six months to thirty years). Early diagnosis, prompt treatment including fasciotomies when indicated, complete debridement, appropriate coverage, meticulous surgical technique, and simultaneous treatment of concomitant injuries are all crucial factors in successful limb salvage. Major arterial injuries of the limb occur frequently in our patient population, especially in time of war. Successful treatment of major arterial injuries may be life-saving, as well as allowing limb salvage and restoration of limb function. The purpose of this study is to review our experience with repair of major arterial injuries.

Adolescent↗
PubMed1993

[The segmental distribution of afferent neurons of liver, and "qi men" point, "tai chong" point in the spinal ganglion].

Experimental animals were 38 cats, 10% HRP 50-60 microliters was injected into "Tai Chong", "Qi Men" points respectively and 10 cats were used for each point. Another 18 cats were injected with 10% HRP 100 microliters into the liver. The segmental distribution of afferent neurons of points and liver was observed under light microscope. We observed the majority of labeled cells in the spinal ganglion. The segmental distribution of afferent neurons of "Tai Chong" point was T12, L1-7 and S1-3. The segmental distribution of afferent neurons of "Qi Men" point was T5-8. The segmental distribution of afferent neurons of liver was T3-12 and L1. The results show that the afferent of "Tai Chong, Qi Men" points and the liver are mutual intersected and overlapped for 2-4 segments. The mutual intersection and overlapping were probably the morphological foundation of treatment of liver disease by needing "Tai Chong", "Qi Men" point, at the same time, the results may elucidate the underlying mechanism of correlation between acupoints and viscera, too.

Acupuncture Points↗
PubMed1993

[The segmental distribution of sympathetic afferent neurons of the heart, cardiac nerve, and projection of the cardiac nerve to the central nervous system].

1. The HRP labeled method was used to study the segmental distribution of sympathetic afferent neurons of the heart. 10%-20% HRP 150 microliters solution was injected around the left coronary artery of 18 cats. The HRP labeled cells were observed in the C8-T10 spinal ganglions, therefore the segmental distribution of sympathetic afferent neurons of the heart were in C8-T10 spinal cord. 2. The segmental distribution of cardiac nerve's afferent neurons was studied, 30% HRP 15 microliters was injected into the cardiac nerve of 18 cats. The HRP labeled cells were observed in the C8-T9 spinal ganglions. 3. CB-HRP 10 microliters was injected into the medium and inferior cardiac nerves. The cardiac nerve's fibers project into T1-5 spinal cord, the HRP labeled fibers were observed in III-VII lamina of spinal cord, and there were connections with III, IV, V, VI, VII laminas. 4. The segmental distribution of sympathetic afferent neurons of heart and cardiac nerve, projection of the cardiac nerve the III-VII laminae of spinal cord and the connection of fibers in the III-VII laminae were the morphologic foundations of referred pain and the heart disease. (tachycordia, angina etc.) treated with acupuncture.

Animals↗
PubMed1993

Dibenzothiazepinones as potential calcium channel antagonists. I.

Certain dibenzo[a,d]cycloheptenes and dibenzo[b,e]thiepins (e.g., 1 and 2) substituted in the 5 and 11-positions, respectively, are potent calcium channel antagonists. It has previously been shown that potency increases with a decrease in the angle between the planes of the flanking aromatic rings, as computed by semi-empirical AM1 calculations with geometry minimization. In the present study, we evaluated a series of dibenzo[b,f]-1,4-thiazepinones (10-14) as potential bioisosteres of these compounds having a slightly more acute angle of flexure. X-Ray diffraction reveals the crystal structure of the parent dibenzo[b,f]-1,4-thiazepinone 4 to have a flexure angle of 108.4 degrees. Due to electron delocalization, the amide moiety in the seven-membered ring adopts a planar conformation. The synthesis of a series of 10-[omega-[4-(4-fluorophenyl)piperazin-1-yl]alkyl]dibenzo[b,f]-1,4 - thiazepin-11(10H)-ones (10-14), and results of their evaluation for calcium channel antagonistic activity on hamster aorta, are presented.

Animals↗
PubMed1993

Cloning of thienamycin biosynthetase genes from Streptomyces cattleya.

A mutant Y3 blocked in the thienamycin biosynthetic pathway was obtained from thienamycin producing strain Streptomyces cattleya by NTG treatment. Preliminary cloning system has been established on the basis of studies on the conditions for protoplast formation, regeneration, as well as DNA transformation for Y3 mutant strain. The shotgun cloning was carried out from S. cattleya using pIJ680 as a vector and the Y3 mutant as a host. The transformant No. 12 produced a thienamycin-like substance identified by paper chromatography and HPLC analysis. A recombinant plasmid p6BC12, which has molecular size of 9.8kb and an insert of 4.5kb, could be recovered. Southern hybridization confirmed that the transformant No. 12 harbors the recombinant plasmid p6BC12. The intermediate accumulated by Y3 mutant was identified as a polypeptide. The product of transformant containing p6BC12 could turn this polypeptide to a bioactivity substance in vitro. This gene can hybridizate with S. lipmanii IPNS gene. We presume that a cyclase gene from S. cattleya was cloned according to the function of the expression product.

Cloning, Molecular↗
PubMed1992

Synthesis, characterization, and Ca2+ antagonistic activity of diltiazem metabolites.

Diltiazem is a calcium antagonist widely used in the treatment of angina and hypertension. The contributions of metabolites of diltiazem to the vasorelaxant effects of diltiazem were investigated. The synthesis and spectroscopic characterization of eight major cis-diltiazem metabolites are described. Three of the compounds--N, O-didemethylated metabolite (21), O-demethylated metabolite (22), and diltiazem N-oxide (27)--have been recently reported and have not previously been synthesized. The identities of all eight synthetic metabolites have been verified with samples obtained from human urine using combined LC-MS/MS. The Ca2+ antagonistic activities of diltiazem and its metabolites (except 27) were studied on hamster aorta preparations depolarized with KCl. The order of potencies (IC50 +/- SE, microM) is as follows: diltiazem (0.98 +/- 0.47) greater than 17 (2.46 +/- 0.38) greater than or equal to 23 (3.27 +/- 1.02) greater than 26 (20.2 +/- 10.5) greater than 22 (40.4 +/- 15.4) greater than or equal to 25 (45.5 +/- 18.1) greater than 21 (112.2 +/- 33.2) greater than or equal to 24 (126.7 +/- 24.2). Structure-activity relationships are also discussed.

Animals↗
PubMed1992

Detection of DNA alterations in human bladder tumors by DNA fingerprint analyses.

DNA fingerprint analyses were used to examine the constitutional and tumor DNA from 22 bladder tumor patients. DNA alterations, such as loss of bands, new bands, and intensity shifts were observed in 10 of the 22 patients. The most frequent DNA alteration, occurring in 80% of the patients, was a complete loss of one or several bands. Fingerprint abnormalities were present both in low-malignant superficial tumors and in high-malignant invasive tumors, but were also lacking in the latter group. Apparently no relationship exists between fingerprint abnormalities and gross chromosomal aberrations or the proportion of S-phase cells as measured by flow cytometry or development of recurrent tumors during a limited observation period. Thus, whether fingerprint aberrations express genetic alterations directly involved in the malignancy potential of bladder carcinoma remains an open question.

Adult↗
PubMed1992

Differential regulation of the transcript levels of some nuclear-encoded and mitochondrial-encoded respiratory-chain components in response to growth activation.

Biogenesis of mammalian mitochondria requires the participation of both nuclear and mitochondrial genes. In order to study the expression and coordination of these two sets of genes, serum-deprived, quiescent NIH 3T3 cells were activated by serum addition. The steady-state levels of the transcripts for two growth-response genes (the mitochondrial adenine-nucleotide translocator and non-mitochondrial beta-actin), one nuclear-encoded respiratory-chain component (F1-ATPase beta-subunit) and the mitochondrial-encoded subunit I of cytochrome oxidase decreased significantly in quiescent cells and were rapidly restored with similar kinetics after addition of serum. The transcripts for two additional nuclear-encoded mitochondrial genes (cytochrome c1 and cytochrome oxidase subunit IV) did not respond to serum deprivation or growth activation. These results imply that mitochondrial biogenesis is at least partially regulated through growth-dependent mechanisms. Furthermore, the expression of nuclear genes encoding mitochondrial respiratory-chain components does not appear to be tightly coordinated, suggesting the existence of multiple control circuits.

3T3 Cells↗
PubMed1992

Effects of chronic nicotine and haloperidol administration on muscarinic receptor-mediated phosphoinositide turnover in rat brain slices.

Muscarinic receptor-mediated phosphoinositide (PI) turnover in rat brain slices was assessed after chronic administration of nicotine (12 mg/kg/day) or haloperidol decanoate (1.5 mg/kg/day), either alone or in combination, for 6 weeks. Nicotine alone did not significantly alter carbachol-induced inositol monophosphate (IP1) accumulation in the frontal cortex, but did result in a significant increase in the hippocampus, and in a decrease in the striatum. Haloperidol alone attenuated carbachol-stimulated IP1 accumulation in all three brain regions. Chronic treatment with combined nicotine and haloperidol resulted in no significant change in carbachol-sensitive IP1 accumulation in either the frontal cortex or hippocampus but did result in a decrease in the striatum. The results suggest significant cross-talk between cholinergic and dopaminergic systems in affecting PI metabolism.

Animals↗
PubMed1992

Intracellular distribution of a nuclear localization signal binding protein.

The transport of proteins into the nucleus requires the recognition of a nuclear localization signal sequence. Several proteins that interact with these sequences have been identified, including one of about 66 kDa. We have prepared antibodies that recognize the 66-kDa nuclear localization signal binding protein (NLSBP) and inhibit nuclear localization in vitro. By immunofluorescence, it is seen that the NLSBP is predominantly cytoplasmic and is distributed peripherally around the nucleus and the microtubule organizing center. There is also a weak punctate staining of the surface of the nucleus. Methanol-fixed cells can also be stained directly with fluorescently labeled karyophilic proteins. These stains reveal the same cytoplasmic structures as anti-NLSBP. The expression of the NLSBP is growth dependent. When cells grown to confluence are examined, the cytoplasmic staining is greatly reduced, leaving the punctate nuclear staining as the predominant feature. In serum-starved cells, very little staining of either the cytoplasm or the nucleus can be seen. Upon simulation by the addition of serum, the original cytoplasmic and nuclear envelope staining is restored. Cells grown in the presence of colchicine or taxol have an altered NLSBP distribution but apparently normal cytoplasmic nuclear transport.

Amino Acid Sequence↗
PubMed1992

Alteration of neuroblastoma ganglioside metabolism by retinoic acid.

Cellular differentiation is often associated with striking changes in ganglioside metabolism. Because retinoic acid causes cellular differentiation in vitro, we have characterized its effect on ganglioside synthesis and shedding by LAN-5 human neuroblastoma cells. Three major observations were made: (a) 20 microM retinoic acid caused a marked (twofold) increase in cellular ganglioside content, with a slight relative enhancement in GD1a and GT1b synthesis, (b) ganglioside shedding increased in parallel with increased cellular ganglioside content, and also, unexpectedly, (c) retinoic acid caused a quantitatively similar increase in content of cell membrane phospholipids, which are also shed. We conclude that enhanced ganglioside synthesis and shedding by retinoic acid are part of a previously undescribed generalized stimulatory effect on membrane lipid metabolism.

Chromatography, Thin Layer↗
PubMed1992

The retinoblastoma gene product regulates Sp1-mediated transcription.

We have demonstrated that the retinoblastoma gene product (Rb) can positively regulate transcription from the fourth promoter of the insulinlike growth factor II gene. Two copies of a motif (the retinoblastoma control element) similar to that found in the human c-fos, transforming growth factor beta 1, and c-myc promoters are responsible for conferring Rb regulation to the fourth promoter of the insulinlike growth factor II gene. We have shown that the transcription factor Sp1 can bind to and stimulate transcription from the retinoblastoma control element motif. Moreover, by using a GAL4-Sp1 fusion protein, we have directly demonstrated that Rb positively regulates Sp1 transcriptional activity in vivo. These results indicate that Rb can function as a positive regulator of transcription and that Sp1 is one potential target, either directly or indirectly, for transcriptional regulation by Rb.

3T3 Cells↗
PubMed1992

Leukocyte cell adhesion proteins: from molecular dissection to clinical applications.

Leukocyte adhesion is needed for a number of leukocyte functions like immunoglobulin synthesis, T and NK-cell-mediated cytotoxicity, phagocytosis by granulocytes, and cellular accumulation in inflamed tissue. Several cell surface molecules involved in leukocyte-leukocyte and leukocyte-target cell interactions have recently been identified and characterized. Both the polypeptide and carbohydrate portions are important in leukocyte interactions. It is becoming increasingly apparent that it is possible to interfere with the normal functions of the leukocyte adhesion glycoproteins, and such applications may become important in medicine.

Animals↗
PubMed1992

[Gingival crevicular aspartate aminotransferase levels in periodontitis patients before and after periodontal treatment].

Gingival crevicular fluid samples were collected from 296 teeth from 40 subjects, including 19 rapidly progressive periodontitis (RPP), 8 chronic adult periodontitis (CAP), 7 marginal gingivitis (MG) and 6 healthy subjects (H). The activities of aspartate aminotransferase (AST) in each sample were tested. The results were as follows: (1) The two groups with destructive periodontal disease (RPP and CAP) had greater GCF-AST levels than that from the two non-destructive groups (MG and H). (2) The GCF-AST activities showed significant positive correlations with clinical periodontal parameters, such as probing depth, attachment loss, bleeding index and suppuration. (3) Four weeks after thorough full-mouth root planing, both clinical parameters and GCF-AST levels decreased significantly. The present study suggests that GCF-AST activity might be a sensitive and objective marker for detection of periodontal tissue destruction and inflammation.

Adult↗
PubMed1992

[Analysis of the linear migration of the radionuclide along meridians in perfused extremities of monkey].

On the basis of researches in human body, further experiment in monkeys was conducted and the result has demonstrated that: 1. There was a close and complicated relation between the migration of 99mTc injected into acupoints and the blood circulation. 2. The location of the migration was mainly in the subcutaneous lay. 3. There were no direct relationship between the migration and periphery nerve system.

Animals↗
PubMed1992

[Morphology and delta-endotoxin proteins of Bacillus thuringiensis from soils and their toxicities to insects].

94 strains of Bacillus thuringiensis were isolated from soils in southwest and northwest of China. The morphology of cells, spores and parasporal crystals of these strains was investigated under transmission and scanning electro-microscope. Proteins of delta-endotoxins from all strains were analysed by rapid SDS-PAGE. 9 species of insects in Lepidoptera, Coleoptera and Diptera were tested for assay of delta-endotoxins. Some kinds of parasporal crystals were quite different in form and in composition of protein from those reported before. Most of strains were nontoxic to all of 9 species used in bio-assay. Some strains were very effective in species of Coleoptera or Noctuidae.

Animals↗
PubMed1992

Construction of hybridomas secreting monoclonal antibody against sweet potato feathery mottle virus and use of antibody for detection of SPFMV.

Two hybridomas stably secreting monoclonal antibodies (McAb) against sweet potato feathery mottle virus (SPFMV) were constructed by fusing mouse myeloma (Sp2/0-Ag14) with mouse splenocytes immunized with SPFMV-LF. The McAb secreted by the two hybridomas specifically reacted with both SPFMV-LF (China strain) and SPFMV-RC (American strain) in dot-blot-ELISA. A large amount of McAb was produced with BALB/c mice. The titer of hybridoma cultured supernatant was 1:256, and that of the ascitic fluids was 1:1 x 10(4); and the immunoglobulins of McAb were IgG2a and IgG3 respectively. The detection of SPFMV-infected sweet potato plants with McAb confirmed that the McAb obtained in this test were desirable for large-scale routine surveys of SPFMV. This study on construction of hybridomas and detection of SPFMV using McAb is the first report in the world.

Animals↗